[
    {
        "anchor": "Active adaptolates: motility-induced percolating structures with an\n  adaptive packing geometry: It is well known that periodic potentials can be used to induce freezing and\nmelting in colloids. Here, we transfer this concept to active systems and find\nthe emergence of a so-far unknown active matter phase in between the frozen\nsolid-like phase and the molten phase. This phase of \"active adaptolates\"\nadopts the geometry of the underlying lattice like the frozen phase, maintains\nballistic dynamics like the molten phase, and percolates. In particular, this\nfinding creates a route to use external fields for designing the intrinsic\nstructure of active systems without qualitatively affecting their dynamics.",
        "positive": "The shear modulus of metastable amorphous solids with strong central and\n  bond-bending interactions: We derive expressions for the shear modulus of deeply-quenched, glassy\nsolids, in terms of a Cauchy-Born free energy expansion around a rigid\n(quenched) reference state, following the approach due to Alexander [Alexander,\nPhys. Rep. 296, 1998]. Continuum-limit explicit expressions of the shear\nmodulus are derived starting from the microscopic Hamiltonians of central and\nbond-bending interactions. The applicability of the expressions to dense\ncovalent glasses as well as colloidal glasses with strongly attractive and\nadhesive bonds is discussed."
    },
    {
        "anchor": "Shear dynamics of an inverted nematic emulsion: Here we study theoretically the dynamics of a 2D and a 3D isotropic droplet\nin a nematic liquid crystal under a shear flow. We find a large repertoire of\npossible nonequilibrium steady states as a function of the shear rate and of\nthe anchoring of the nematic director field at the droplet surface. We first\ndiscuss homeotropic anchoring. For weak anchoring, we recover the typical\nbehaviour of a sheared isotropic droplet in a binary fluid, which rotates,\nstretches and can be broken by the applied flow. For intermediate anchoring,\nnew possibilities arise due to elastic effects in the nematic fluid. We find\nthat in this regime the 2D droplet can tilt and move in the flow, or tumble\nincessantly at the centre of the channel. For sufficiently strong anchoring,\nfinally, one or both of the topological defects which form close to the surface\nof the isotropic droplet in equilibrium detach from it and get dragged deep\ninto the nematic state by the flow. In 3D, instead, the Saturn ring associated\nwith normal anchoring disclination line can be deformed and shifted downstream\nby the flow, but remains always localized in proximity of the droplet, at least\nfor the parameter range we explored. Tangential anchoring in 2D leads to a\ndifferent dynamic response, as the boojum defects characteristic of this\nsituation can unbind from the droplet under a weaker shear with respect to the\nnormal anchoring case. Our results should stimulate further experiments with\ninverted liquid crystal emulsions under shear, as most of the predictions can\nbe testable in principle by monitoring the evolution of liquid crystalline\norientation patterns or by tracking the position and shape of the droplet over\ntime.",
        "positive": "Transition pathways in Cylinder-Gyroid interface: When two distinct ordered phases contact, the interface may exhibit rich and\nfascinating structures. Focusing on the Cylinder-Gyroid interface system,\ntransition pathways connecting various interface morphologies are studied armed\nwith the Landau--Brazovskii model. Specifically, minimum energy paths are\nobtained by computing transition states with the saddle dynamics. We present\nfour primary transition pathways connecting different local minima,\nrepresenting four different mechanisms of the formation of the Cylinder-Gyroid\ninterface. The connection of Cylinder and Gyroid can be either direct or\nindirect via Fddd with three different orientations. Under different\ndisplacements, each of the four pathways may have the lowest energy."
    },
    {
        "anchor": "Sorting of Chiral Microswimmers: Microscopic swimmers, e.g., chemotactic bacteria and cells, are capable of\ndirected motion by exerting a force on their environment. For asymmetric\nmicroswimmers, e.g., bacteria, spermatozoa and many artificial active colloidal\nparticles, a torque is also present leading in two dimensions to circular\nmotion and in three dimensions to helicoidal motion with a well-defined\nchirality. Here, we demonstrate with numerical simulations in two dimensions\nhow the chirality of circular motion couples to chiral features present in the\nmicroswimmer environment. Levogyre and dextrogyre microswimmers as small as\n$50\\,\\mathrm{nm}$ can be separated and selectively trapped in \\emph{chiral\nflowers} of ellipses. Patterned microchannels can be used as \\emph{funnels} to\nrectify the microswimmer motion, as \\emph{sorters} to separate microswimmers\nbased on their linear and angular velocities, and as \\emph{sieves} to trap\nmicroswimmers with specific parameters. We also demonstrate that these results\ncan be extended to helicoidal motion in three dimensions.",
        "positive": "Chirality modifies the interaction between knots: In this study we consider an idealization of a typical optical tweezers\nexperiment involving a semiflexible double-knotted polymer, with steric\nhindrance and persistence length matching those of dsDNA in high salt\nconcentration, under strong stretching. Using exhaustive Molecular Dynamics\nsimulations we show that not only does a double-knotted dsDNA filament under\ntension possess a free energy minimum when the two knots are intertwined, but\nalso that the depth of this minimum depends on the relative chirality of the\ntwo knots. We rationalize this dependence of the effective interaction on the\nchirality in terms of a competition between chain entropy and bending energy."
    },
    {
        "anchor": "Mapping electrostatic potential in electrolyte solution: Mapping the electrostatic potential (ESP) distribution around ions in\nelectrolyte solution is crucial for the establishment of a microscopic\nunderstanding of electrolyte solution properties. For solutions in the bulk\nphase, it has not been possible to measure the ESP distribution on Angstrom\nscale. Here we show that liquid electron scattering experiment using\nstate-of-the-art relativistic electron beam can be used to measure the Debye\nscreening length of aqueous LiCl, KCl, and KI solutions across a wide range of\nconcentrations. We observe that the Debye screening length is long-ranged at\nlow concentration and short-ranged at high concentration, providing key insight\ninto the decades-long debate over whether the impact of ions in water is\nlong-ranged or short-ranged. In addition, we show that the measured ESP can be\nused to retrieve the non-local dielectric function of electrolyte solution,\nwhich can serve as a promising route to investigate the electrostatic origin of\nspecial ion effects. Our observations show that, interaction, as one of the two\nfundamental perspectives for understanding electrolyte solution, can provide\nmuch richer information than structure.",
        "positive": "Creep and flow of glasses: strain response linked to the spatial\n  distribution of dynamical heterogeneities: Mechanical properties are of central importance to materials sciences, in\nparticular if they depend on external stimuli. Here we investigate the\nrheological response of amorphous solids, namely col- loidal glasses, to\nexternal forces. Using confocal microscopy and computer simulations, we\nestablish a quantitative link between the macroscopic creep response and the\nmicroscopic single-particle dy- namics. We observe dynamical heterogeneities,\nnamely regions of enhanced mobility, which remain localized in the creep\nregime, but grow for applied stresses leading to steady flow. These different\nbehaviors are also reflected in the average particle dynamics, quantified by\nthe mean squared dis- placement of the individual particles, and the fraction\nof active regions. Both microscopic quantities are found to be proportional to\nthe macroscopic strain, despite the non-equilibrium and non-linear conditions\nduring creep and the transient regime prior to steady flow."
    },
    {
        "anchor": "Ionic conductivity on a wetting surface: Recent experiments measuring the electrical conductivity of DNA molecules\nhighlight the need for a theoretical model of ion transport along a charged\nsurface. Here we present a simple theory based on the idea of unbinding of ion\npairs. The strong humidity dependence of conductivity is explained by the\ndecrease in the electrostatic self-energy of a separated pair when a layer of\nwater (with high dielectric constant) is adsorbed to the surface. We compare\nour prediction for conductivity to experiment, and discuss the limits of its\napplicability.",
        "positive": "Electrical conductivity of quasi-two-dimensional foams: Quasi-two-dimensional (quasi-2D) foams consist of monolayers of bubbles\nsqueezed between two narrowly spaced plates. These simplified foams have served\nsuccessfully in the past to shed light on numerous issues in foam physics. Here\nwe consider the electrical conductivity of such model foams. We compare\nexperiments to a model which we propose, and which successfully relates the\nstructural and the conductive properties of the foam over the full range of the\ninvestigated liquid content. We show in particular that in the case of quasi-2D\nfoams the liquid in the nodes needs to be taken into account even at low liquid\ncontent. We think that these results may provide different approaches for the\ncharacterization of foam properties and for the in situ characterization of the\nliquid content of foams in confining geometries, such as microfluidics"
    },
    {
        "anchor": "Statistical properties of gravity-driven granular discharge flow under\n  the influence of an obstacle: Two-dimensional granular discharge flow driven by gravity under the influence\nof an obstacle is experimentally investigated. A horizontal exit of width $W$\nis opened at the bottom of vertical Hele-Shaw cell filled with stainless-steel\nparticles to start the discharge flow. In this experiment, a circular obstacle\nis placed in front of the exit. Thus, the distance between the exit and\nobstacle $L$ is also an important parameter. During the discharge,\ngranular-flow state is acquired by a high-speed camera. The bulk discharge-flow\nrate is also measured by load cell sensors. The obtained high-speed-image data\nare analyzed to clarify the particle-level granular-flow dynamics. Using the\nmeasured data, we find that the obstacle above the exit affects the\ngranular-flow field. Specifically, the existence of obstacle results in large\nhorizontal granular temperature and small packing fraction. This tendency\nbecomes significant when $L$ is smaller than approximately 6$D_g$ when $W\n\\simeq 4 D_g$, where $D_g$ is diameter of particles.",
        "positive": "Energy dissipation in sheared wet granular assemblies: Energy dissipation in sheared dry and wet granulates is considered in the\npresence of an externally applied confining pressure. Discrete element\nsimulations reveal that for sufficiently small confining pressures, the energy\ndissipation is dominated by the effects related to the presence of cohesive\nforces between the particles. The residual resistance against shear can be\nquantitatively explained by a combination of two effects arising in a wet\ngranulate: i) enhanced friction at particle contacts in the presence of\nattractive capillary forces, and ii) energy dissipation due to the rupture and\nreformation of liquid bridges. Coulomb friction at grain contacts gives rise to\nan energy dissipation which grows linearly with increasing confining pressure,\nfor both dry and wet granulates. Because of a lower Coulomb friction\ncoefficient in the case of wet grains, as the confining pressure increases the\nenergy dissipation for dry systems is faster than for wet ones."
    },
    {
        "anchor": "Defects and Frustration in the Packing of Soft Balls: This work introduces the Hookean-Voronoi energy, a minimal model for the\npacking of soft, deformable balls. This is motivated by recent studies of\nquasi-periodic equilibria arising from dense packings of diblock and star\npolymers. Restricting to the planar case, we investigate the equilibrium\npackings of identical, deformable objects whose shapes are determined by an\n$N$-site Voronoi tessellation of a periodic rectangle. We derive a reduced\nformulation of the system showing at equilibria each site must reside at the\n``max-center'' of its associated Voronoi region and construct a family of\nordered ``single-string'' minimizers whose cardinality is $O(N^2)$. We identify\nsharp conditions under which the system admits a regular hexagonal tessellation\nand establish that in all cases the average energy per site is bounded below by\nthat of a regular hexagon of unit size. However, numerical investigation of\ngradient flow of random initial data, reveals that for modest values of $N$ the\nsystem preponderantly equilibrates to quasi-ordered states with low energy and\nlarge basins of attraction. For larger $N$ the distribution of equilibria\nenergies appears to approach a $\\delta$-function limit, whose energy is\nsignificantly higher than the ground state hexagon. This limit is possibly\nshaped by two mechanisms: a proliferation of moderate-energy disordered\nequilibria that block access of the gradient flow to lower energy quasi-ordered\nstates and a rigid threshold on the maximum energy of stable states.",
        "positive": "Stochastic Kinetic Theory for Collective Behavior of Hydrodynamically\n  Interacting Active Particles: Self-propelled particles with hydrodynamic interactions (microswimmers) have\npreviously been shown to produce long-range ordering phenomena. Many\ntheoretical explanations for these collective phenomena are connected to\ninstabilities in the hydrodynamic or kinetic equations. By incorporating\nstochastic fluxes into the mean field kinetic equation, we quantify the\ndynamics of a suspension of microswimmers in the parameter regime where the\ndeterministic equation is stable. We can thereby compute nontrivial collective\nphenomena concerning spatial correlations of orientation and stress as well as\nthe enhanced diffusion of tracer particles. Our analysis here focuses primarily\non two-dimensional systems, though we also show how superdiffusion of tracers\nin three dimensions can occur by our framework."
    },
    {
        "anchor": "Configurational entropy of skyrmions and half-skyrmions in planar\n  magnetic elements: This works deals with the presence of localized planar structures in magnetic\nmaterials that admit integer or half-integer topological charge. We study\nmodels in which the internal disposition of magnetization is driven by a single\nparameter, that controls the topological charge density of the magnetic\nstructure. In particular, we focus mainly on the configurational entropy of\nthese skyrmions and half-skyrmions and show how to increase or diminish their\ninformational capabilities.",
        "positive": "Currents and flux-inversion in photokinetic active particles: Many active particles, both of biological and synthetic origin, can have a\nlight controllable propulsion speed, a property that in biology is commonly\nreferred to as photokinesis. Here we investigate directed transport of\nphotokinetic particles by traveling light patterns. We find general expressions\nfor the current in the cases where the motility wave, induced by light, shifts\nvery slow or very fast. These asymptotic formulas are independent on the shape\nof the wave and are valid for a wide class of active particle models. Moreover\nwe derive an exact solution for the one-dimensional \"run and tumble\" model. Our\nresults could be used to design time-varying illumination patterns for fast and\nefficient spatial reconfiguration of photokinetic colloids or bacteria."
    },
    {
        "anchor": "Experimental observation of directional locking and dynamical ordering\n  of colloidal monolayers driven across quasiperiodic substrates: We experimentally investigate the structural behavior of an interacting\ncolloidal monolayer being driven across a decagonal quasiperiodic potential\nlandscape created by an optical interference pattern. When the direction of the\ndriving force is varied, we observe the monolayer to be directionally locked on\nangles corresponding to the symmetry axes of the underlying potential. At such\nlocking steps we observe a dynamically ordered smectic phase in agreement with\nrecent simulations. We demonstrate, that such dynamical ordering is due to the\ninteraction of particle lanes formed by interstitial and non-interstitial\nparticles.",
        "positive": "Simultaneous measurement of mass and rotation of trapped absorbing\n  particles in air: We trap absorbing micro-particles in air by photophoretic forces generated\nusing a single loosely focused Gaussian trapping beam. We measure a component\nof the radial Brownian motion of a trapped particle cluster and determine the\npower spectral density, mean squared displacement, and normalized position and\nvelocity autocorrelation functions in order to characterize the photophoretic\nbody force in a quantitative fashion for the first time. The trapped particles\nalso undergo spontaneous rotation due to the action of this force. This is\nevident from the spectral density that displays clear peaks at the rotation and\nthe particles' inertial resonance frequencies. We fit the spectral density to\nthe well-known analytical function derived from the Langevin equation, measure\nthe resonance and rotation frequencies and determine values for particle mass\nthat we verify at different trapping laser powers with reasonable accuracy."
    },
    {
        "anchor": "Theory and simulations of rigid polyelectrolytes: We present theoretical and numerical studies on stiff, linear\npolyelectrolytes within the framework of the cell model. We first review\nanalytical results obtained on a mean-field Poisson-Boltzmann level, and then\nuse molecular dynamics simulations to show, under which circumstances these\nfail quantitatively and qualitatively. For the hexagonally packed nematic phase\nof the polyelectrolytes we compute the osmotic coefficient as a function of\ndensity. In the presence of multivalent counterions it can become negative,\nleading to effective attractions. We show that this results from a reduced\ncontribution of the virial part to the pressure. We compute the osmotic\ncoefficient and ionic distribution functions from Poisson-Boltzmann theory with\nand without a recently proposed correlation correction, and also simulation\nresults for the case of poly(para-phenylene) and compare it to recently\nobtained experimental data on this stiff polyelectrolyte. We also investigate\nion-ion correlations in the strong coupling regime, and compare them to\npredictions of the recently advocated Wigner crystal theories.",
        "positive": "Confotronic Dynamics of Tubular Lattices: Tubular lattices are ubiquitous in nature and technology. Microtubules and\nnanotubes of all kinds act as important pillars of biological cells and the\nman-made nano-world. We show that when prestress is introduced in such\nstructures, localized conformational quasiparticles emerge and govern the\ncollective shape dynamics of the lattice.\n  When coupled via cooperative interactions these quasiparticles form\nlarger-scale quasipolymer superstructures exhibiting collective dynamic modes\nand giving rise to a hallmark behavior radically different from semiflexible\nbeams."
    },
    {
        "anchor": "Assessing molecular simulation for the analysis of lipid monolayer\n  reflectometry: Using molecular simulation to aid in the analysis of neutron reflectometry\nmeasurements is commonplace. However, reflectometry is a tool to probe\nlarge-scale structures, and therefore the use of all-atom simulation may be\nirrelevant. This work presents the first direct comparison between the\nreflectometry profiles obtained from different all-atom and coarse-grained\nmolecular dynamics simulations. These are compared with a traditional model\nlayer structure analysis method to determine the minimum simulation resolution\nrequired to accurately reproduce experimental data. We find that systematic\nlimits reduce the efficacy of the MARTINI potential model, while the Berger\nunited-atom and Slipids all-atom potential models agree similarly well with the\nexperimental data. The model layer structure gives the best agreement, however,\nthe higher resolution simulation-dependent methods produce an agreement that is\ncomparable. Finally, we use the atomistic simulation to advise on possible\nimprovements that may be offered to the model layer structures, creating a more\nrealistic monolayer model.",
        "positive": "Pretransitional behavior in a water-DDAB-5CB microemulsion close to the\n  demixing transition. Evidence for intermicellar attraction mediated by\n  paranematic fluctuations: We present a study of a water-in-oil microemulsion in which surfactant coated\nwater nanodroplets are dispersed in the isotropic phase of the thermotropic\nliquid crystal 5CB. As the temperature is lowered below the isotropic to\nnematic phase transition of pure 5CB, the system displays a demixing transition\nleading to a coexistence of a droplet rich isotropic phase with a droplet poor\nnematic. The transition is anticipated, in the high T side, by increasing\npretransitional fluctuations in 5CB molecular orientation and in the\nnanodroplet concentration. The observed phase behavior supports the notion that\nthe nanosized droplets, while large enough for their statistical behavior to be\nprobed via light scattering, are also small enough to act as impurities,\ndisturbing the local orientational ordering of the liquid crystal and thus\nexperiencing pretransitional attractive interaction mediated by paranematic\nfluctuations. The pretransitional behavior, together with the topology of the\nphase diagram, can be understood on the basis of a diluted Lebwohl-Lasher model\nwhich describes the nanodroplets simply as holes in the liquid crystal."
    },
    {
        "anchor": "A simple approximation for fluids with narrow attractive potentials: We study a simple modification of the optimized random phase approximation\n(ORPA) aimed at improving the performance of the theory for interactions with a\nnarrow attractive well by taking into account contributions to the direct\ncorrelation function non-linear in the interaction. The theory is applied to a\nhard-core Yukawa and a square-well potential. Results for the equation of\nstate, the correlations, and the critical point have been obtained for\nattractions of several ranges, and compared with Monte Carlo simulations. When\nthe attractive interaction is narrow, the modified ORPA significantly improves\nover the plain one, especially with regard to the consistency between different\nroutes to the thermodynamics, the two-body correlation function, and the\ncritical temperature. However, while the spinodal curve of the modified theory\nis accessible, the liquid-vapor coexistence curve is not. A possible strategy\nto overcome this drawback is suggested.",
        "positive": "The coherent scattering function in the reptation model: analysis beyond\n  asymptotic limits: We calculate the coherent dynamical scattering function S_c(q,t;N) of a\nflexible chain of length N, diffusing through an ordered background of\ntopological obstacles. As an instructive generalization, we also calculate the\nscattering function S_c(q,t;M,N) for the central piece of length M < N of the\nchain. Using the full reptation model, we treat global creep, tube length\nfluctuations, and internal relaxation within a consistent and unified approach.\nOur theory concentrates on the universal aspects of reptational motion, and our\nresults in all details show excellent agreement with our simulations of the\nEvans-Edwards model, provided we allow for a phenomenological prefactor which\naccounts for non-universal effects of the micro-structure of the Monte Carlo\nchain, present for short times. Previous approaches to the coherent structure\nfunction can be analyzed as special limits of our theory. First, the effects of\ninternal relaxation can be isolated by studying the limit $N \\to \\infty$, M\nfixed. The results do not support the model of a `Rouse chain in a tube'. We\ntrace this back to the non-equilibrium initial conditions of the latter model.\nSecond, in the limit of long chains $(M = N \\to \\infty)$ and times large\ncompared to the internal relaxation time $(t/N^2 \\to \\infty)$, our theory\nreproduces the results of the primitive chain model. This limiting form applies\nonly to extremely long chains, and for chain lengths accessible in practice,\neffects of, e.g., tube length fluctuations are not negligible."
    },
    {
        "anchor": "Active particles with polar alignment in ring-shaped confinement: We study steady-state properties of a suspension of active, nonchiral and\nchiral, Brownian particles with polar alignment and steric interactions\nconfined within a ring-shaped (annulus) confinement in two dimensions.\nExploring possible interplays between polar interparticle alignment, geometric\nconfinement and the surface curvature, being incorporated here on minimal\nlevels, we report a surface-population reversal effect, whereby active\nparticles migrate from the outer concave boundary of the annulus to accumulate\non its inner convex boundary. This contrasts the conventional picture, implying\nstronger accumulation of active particles on concave boundaries relative to the\nconvex ones. The population reversal is caused by both particle alignment and\nsurface curvature, disappearing when either of these factors is absent. We\nexplore the ensuing consequences for the chirality-induced current and swim\npressure of active particles and analyze possible roles of system parameters,\nsuch as the mean number density of particles and particle self-propulsion,\nchirality and alignment strengths.",
        "positive": "Dynamical mechanism for non-locality in dense granular flows: The dynamical mechanism at the origin of the non-local rheology of dense\ngranular flows is investigated trough discrete element simulations. We show\nthat the influence of a shear band on the mechanical behavior of a distant zone\nis contained in the spatial variations observed in the network of granular\ncontacts. Using a micro-rheology technique, we establish that the exponential\nresponses hence obtained, do not proof the validity of a mechanical activation\nprocess as previously suggested, but stem from the spatial relaxation of the\nshear rate as a direct consequence of a macroscopic non-local constitutive\nrelation. Finally, by direct visualization of the local relaxation processes,\nwe dismiss the kinetic elasto-plastic picture, where a flow is conceived as a\nquasi-static sequence of localized plastic events interacting through the\nstress field. We therefore conclude in favor of the jamming scenario, where\ngeometrical constrains lead to coherent non-affine displacements along floppy\nmodes, inherently non-local."
    },
    {
        "anchor": "On the distribution of DNA translocation times in solid-state nanopores:\n  an analysis using Schrodinger's first-passage-time theory: In this short note, a correction is made to the recently proposed solution\n[1] to a 1D biased diffusion model for linear DNA translocation and a new\nanalysis will be given to the data in [1]. It was pointed out [2] by us\nrecently that this 1D linear translocation model is equivalent to the one that\nwas considered by Schrodinger [3] for the Enrenhaft-Millikan measurements [4,5]\non electron charge. Here we apply Schrodinger's first-passage-time distribution\nformula to the data set in [1]. It is found that Schrodinger's formula can be\nused to describe the time distribution of DNA translocation in solid-state\nnanopores. These fittings yield two useful parameters: drift velocity of DNA\ntranslocation and diffusion constant of DNA inside the nanopore. The results\nsuggest two regimes of DNA translocation: (I) at low voltages, there are clear\ndeviations from Smoluchowski's linear law of electrophoresis [6] which we\nattribute to the entropic barrier effects; (II) at high voltages, the\ntranslocation velocity is a linear function of the applied electric field. In\nregime II, the apparent diffusion constant exhibits a quadratic dependence on\napplied electric field, suggesting a mechanism of Taylor dispersion effect\nlikely due the electro-osmotic flow field in the nanopore channel. This\nanalysis yields a dispersion-free diffusion constant value for the segment of\nDNA inside the nanopore which is in agreement with Stokes-Einstein theory\nquantitatively. The implication of Schrodinger's formula for DNA sequencing is\ndiscussed.",
        "positive": "Capturing Subdiffusive Solute Dynamics and Predicting Selectivity in\n  Nanoscale Pores with Time Series Modeling: Mathematically modeling complex transport phenomena at the molecular level\ncan be a powerful tool for identifying transport mechanisms and predicting\nmacroscopic properties. We use two different stochastic time series models,\nparameterized from long molecular dynamics (MD) simulation trajectories of a\ncross-linked HII phase lyotropic liquid crystal (LLC) membrane, in order to\npredict solute mean squared displacements (MSDs) and solute flux, and thus\nsolute selectivity, in macroscopic length pores. First, using anomalous\ndiffusion theory, we show how solute dynamics can be modeled as a fractional\ndiffusion process subordinate to a continuous time random walk. From the MD\nsimulations, we parameterize the distribution of dwell times, hop lengths\nbetween dwells and correlation between hops. We explore two variations of the\nanomalous diffusion modeling approach. The first applies a single set of\nparameters to the solute displacements and the second applies two sets of\nparameters based on the solute's radial distance from the closest pore center.\nNext, we generalize Markov state models, treating the configurational states of\nthe system as a Markov process where each state has distinct transport\nproperties. For each state and transition between states, we parameterize the\ndistribution and temporal correlation structure of positional fluctuations as a\nmeans of characterization and to allow us to predict solute MSDs. Qualitative\ndifferences between MD and Markov state dependent model-generated trajectories\nmay limit its usefulness. Finally, we demonstrate how one can use these models\nto estimate flux of a solute across a macroscopic-length pore and, based on\nthose quantities, the membrane's selectivity towards each solute. This work\nhelps to connect microscopic chemically-dependent solute motions that do not\nfollow simple diffusive behavior with macroscopic membrane performance."
    },
    {
        "anchor": "Depletion forces between non-spherical objects: We extend the insertion approach for calculating depletion potentials to the\ncase of non-spherical solutes. Instead of a brute-force calculation we suggest\nto employ the recently developed curvature expansion of density profiles close\nto complexly shaped walls. The approximations introduced in the calculation by\nthe use of the curvature expansion and of weight functions for non-spherical\nobjects can be tested independently. As an application for our approach we\ncalculate and discuss the depletion potential between two hard oblate\nellipsoids in a solvent of hard spheres. For this system we calculate the\nentropic force and torque acting on the objects.",
        "positive": "Active nematics with quenched disorder: We introduce a two-dimensional active nematic with quenched disorder. We\nwrite the coarse-grained hydrodynamic equations of motion for slow variables,\nviz. density, and orientation. Disorder strength is tuned from zero to large\nvalues. Results from the numerical solution of equations of motion as well as\nthe calculation of two-point orientation correlation function using linear\napproximation show that the ordered steady-state follows a disorder-dependent\ncrossover from quasi long-range order (QLRO) to short-range order (SRO). Such\ncrossover is due to the pinning of +1/2 and -1/2 topological defects in the\npresence of finite disorder, which breaks the system in uncorrelated domains.\nFinite disorder slows the dynamics of +1/2 defect, and it leads to slower\ngrowth dynamics. The two-point correlation functions for the density and\norientation fields show good dynamic scaling but no static scaling for the\ndifferent disorder strengths. Our findings can motivate experimentalists to\nverify the results and find applications in living and artificial apolar\nsystems in the presence of a quenched disorder."
    },
    {
        "anchor": "Geometry and mechanics of disclination lines in 3D nematic liquid\n  crystals: In 3D nematic liquid crystals, disclination lines have a range of geometric\nstructures. Locally, they may resemble $+1/2$ or $-1/2$ defects in 2D nematic\nphases, or they may have 3D twist. Here, we analyze the structure in terms of\nthe director deformation modes around the disclination, as well as the nematic\norder tensor inside the disclination core. Based on this analysis, we construct\na vector to represent the orientation of the disclination, as well as tensors\nto represent higher-order structure. We apply this method to simulations of a\n3D disclination arch, and determine how the structure changes along the contour\nlength. We then use this geometric analysis to investigate three types of\nforces acting on a disclination: Peach-Koehler forces due to external stress,\ninteraction forces between disclination lines, and active forces. These results\napply to the motion of disclination lines in both conventional and active\nliquid crystals.",
        "positive": "Optimal packing of polydisperse hard-sphere fluids II: We consider the consequences of keeping the total surface fixed for a\npolydisperse system of $N$ hard spheres. In contrast with a similar model (J.\nZhang {\\it et al.}, J. Chem. Phys. {\\bf 110}, 5318 (1999)), the Percus-Yevick\nand Mansoori equations of state work very well and do not show a breakdown. For\nhigh pressures Monte Carlo simulation we show three mechanically stable\npolydisperse crystals with either a unimodal or bimodal particle-size\ndistributions."
    },
    {
        "anchor": "Surface depression with double-angle geometry during the discharge of\n  close-packed grains from a silo: When rough grains in standard packing conditions are discharged from a silo,\na conical depression with a single slope is formed at the surface. We observed\nthat the increase of the volume fraction generates a more complex depression\ncharacterized by two angles of discharge: a lower angle close to the one\nmeasured for standard packing and a considerably larger upper angle. The change\nin slope appears at the boundary between a densely packed stagnant region at\nthe periphery and the central flowing channel formed over the aperture. Since\nthe material in the latter zone is always fluidized, the flow rate is\nunaffected by the initial packing of the bed. On the other hand, the contrast\nbetween both angles is markedly smaller when smooth particles of the same size\nand density are used, which reveals that high volume fraction and friction must\ncombine to produce the observed geometry. Our results show that the surface\nprofile helps to identify by simple visual inspection the packing conditions of\na granular bed, and this can be useful to prevent undesirable collapses during\nsilo discharge in industry.",
        "positive": "Nano-domain formation in charged membranes: Beyond Debye-Huckel\n  approximation: We investigate the microphase separation in a membrane composed of charged\nlipid, by taking into account explicitly the electrostatic potential and the\nion densities in the surrounding solvent. While the overall (membrane and\nsolvent) charge neutrality is assumed, the membrane can have a non-zero net\ncharge. The static structure factor in the homogeneous state is analytically\nobtained without using the Debye-Huckel approximation and is found to have a\npeak at an intermediate wave number. For a binary membrane composed of anionic\nand neutral lipids, the characteristic wave number corresponds to a scale from\nseveral to tens of nanometers. Our numerical calculation further predicts the\nexistence of nano-domains in charged membranes."
    },
    {
        "anchor": "Coherence Properties of Guided-Atom Interferometers: We present a detailed investigation of the coherence properties of beam\nsplitters and Mach-Zehnder interferometers for guided atoms. It is demonstrated\nthat such a setup permits coherent wave packet splitting and leads to the\nappearance of interference fringes. We study single-mode and thermal input\nstates and show that even for thermal input states interference fringes can be\nclearly observed, thus demonstrating the multimode operation and the robustness\nof the interferometer.",
        "positive": "Force-velocity relation and density profiles for biased diffusion in an\n  adsorbed monolayer: In this paper, which completes our earlier short publication [Phys. Rev.\nLett. 84, 511 (2000)], we study dynamics of a hard-core tracer particle (TP)\nperforming a biased random walk in an adsorbed monolayer, composed of mobile\nhard-core particles undergoing continuous exchanges with a vapor phase. In\nterms of an approximate approach, based on the decoupling of the third-order\ncorrelation functions, we obtain the density profiles of the monolayer\nparticles around the TP and derive the force-velocity relation, determining the\nTP terminal velocity, V_{tr}, as the function of the magnitude of external bias\nand other system's parameters. Asymptotic forms of the monolayer particles\ndensity profiles at large separations from the TP, and behavior of V_{tr} in\nthe limit of small external bias are found explicitly."
    },
    {
        "anchor": "Hydrodynamic description of (visco)elastic composite materials and\n  relative strains as a new macroscopic variable: One possibility to adjust material properties to a specific need is to embed\nunits of one substance into a matrix of another substance. Even materials that\nare readily tunable during operation can be generated in this way. In\n(visco)elastic substances, both the matrix material as well as the inclusions\nand/or their immediate environment can be dynamically deformed. If the typical\ndynamic response time of the inclusions and their surroundings approach the\nmacroscopic response time, their deformation processes need to be included into\na dynamic macroscopic characterization. Along these lines, we present a\nhydrodynamic description of (visco)elastic composite materials. For this\npurpose, additional strain variables reflect the state of the inclusions and\ntheir immediate environment. These additional strain variables in general are\nnot set by a coarse-grained macroscopic displacement field. Apart from that,\nduring our derivation, we also include the macroscopic variables of relative\ntranslations and relative rotations that were previously introduced in\ndifferent contexts. As a central point, our approach reveals and classifies the\nimportance of a new macroscopic variable: relative strains. We analyze two\nsimplified minimal example geometries as an illustration.",
        "positive": "Correcting artifacts from finite image size in Differential Dynamic\n  Microscopy: Differential Dynamic Microscopy (DDM) analyzes traditional real-space\nmicroscope images to extract information on sample dynamics in a way akin to\nlight scattering, by decomposing each image in a sequence into Fourier modes,\nand evaluating their time correlation properties. DDM has been applied in a\nnumber of soft-matter and colloidal systems. However, objects observed to move\nout of the microscope's captured field of view, intersecting the edges of the\nacquired images, can introduce spurious but significant errors in the\nsubsequent analysis. Here we show that application of a spatial windowing\nfilter to images in a sequence before they enter the standard DDM analysis can\nreduce these artifacts substantially. Moreover, windowing can increase\nsignificantly the accessible range of wave vectors probed by DDM, and may\nfurther yield unexpected information, such as the size polydispersity of a\ncolloidal suspension."
    },
    {
        "anchor": "Growing length scale in gravity-driven dense granular flow: We report simulations of a two-dimensional, dense, bidisperse system of\ninelastic hard disks falling down a vertical tube under the influence of\ngravity. We examine the approach to jamming as the average flow of particles\ndown the tube is slowed by making the outlet narrower. Defining coarse-grained\nvelocity and stress fields, we study two-point temporal and spatial correlation\nfunctions of these fields in a region of the tube where the time-averaged\nvelocity is spatially uniform. We find that fluctuations in both velocity and\nstress become increasingly correlated as the system approaches jamming. We\nextract a growing length scale and time scale from these correlations.",
        "positive": "Silo discharge of mixtures of soft and rigid grains: We study the outflow dynamics and clogging phenomena of mixtures of soft,\nelastic low-friction spherical grains and hard frictional spheres of similar\nsize in a quasi-two-dimensional (2D) silo with narrow orifice at the bottom.\nPrevious work has demonstrated the crucial influence of elasticity and friction\non silo discharge. We show that the addition of small amounts, even as low as\n5\\%, of hard grains to an ensemble of soft, low-friction grains already has\nsignificant consequences. The mixtures allow a direct comparison of the\nprobabilities of the different types of particles to clog the orifice. We\nanalyze these probabilities for the hard, frictional and the soft, slippery\ngrains on the basis of their participation in the blocking arches, and compare\noutflow velocities and durations of non-permanent clogs for different\ncompositions of the mixtures. Experimental results are compared with numerical\nsimulations. The latter strongly suggest a significant influence of the\ninter-species particle friction."
    },
    {
        "anchor": "Mechanical Responses and Stress Fluctuations of a Supercooled Liquid in\n  a Sheared Non-Equilibrium State: A steady shear flow can drive supercooled liquids into a non-equilibrium\nstate. Using molecular dynamics simulations under steady shear flow\nsuperimposed with oscillatory shear strain for a probe, non-equilibrium\nmechanical responses are studied for a model supercooled liquid composed of\nbinary soft spheres. We found that even in the strongly sheared situation, the\nsupercooled liquid exhibits surprisingly isotropic responses to oscillating\nshear strains applied in three different components of the strain tensor. Based\non this isotropic feature, we successfully constructed a simple two-mode\nMaxwell model that can capture the key features of the storage and loss moduli,\neven for highly non-equilibrium state. Furthermore, we examined the correlation\nfunctions of the shear stress fluctuations, which also exhibit isotropic\nrelaxation behaviors in the sheared non-equilibrium situation. In contrast to\nthe isotropic features, the supercooled liquid additionally demonstrates\nanisotropies in both its responses and its correlations to the shear stress\nfluctuations. Using the constitutive equation (a two-mode Maxwell model), we\ndemonstrated that the anisotropic responses are caused by the coupling between\nthe oscillating strain and the driving shear flow. We measured the magnitude of\nthis violation in terms of the effective temperature. It was demonstrated that\nthe effective temperature is notably different between different components,\nwhich indicates that a simple scalar mapping, such as the concept of an\neffective temperature, oversimplifies the true nature of supercooled liquids\nunder shear flow. An understanding of the mechanism of isotropies and\nanisotropies in the responses and fluctuations will lead to a better\nappreciation of these violations of the FDT, as well as certain consequent\nmodifications to the concept of an effective temperature.",
        "positive": "Density scaling in the mechanics of a disordered mechanical\n  meta-material: Nature provides examples of self-assemble lightweight disordered network\nstructures with remarkable mechanical properties which are desirable for many\napplications purposes but challenging to reproduce artificially. Previous\nexperimental and computational studies investigated the mechanical responses of\nrandom network structures focusing on topological and geometrical aspects in\nterms of variable connectivity or probability to place beam elements. However\nfor practical purposes an ambitious challenge is to design new materials with\nthe possibility to taylor their mechanical features such as stiffness. Here, we\ndesign a two dimensional disordered mechanical meta-material exhibiting\nunconventional stiffness-density scaling in the regime where both bending and\nstretching are relevant for deformation. In this regime, the mechanical\nmeta-material covers a wide interval of the Young modulus - density plane,\nsimultaneously exhibiting high critical stress and critical strain. Our\nresults, supported by finite element simulations, provides the guiding\nprinciples to design on demand disordered metamaterials, bridging the gap\nbetween artificial and naturally occurring materials."
    },
    {
        "anchor": "General Predictive Framework for Droplet Detachment Force: Liquid droplets hanging from solid surfaces are commonplace, but their\nphysics is complex. Examples include dew or raindrops hanging onto wires or\ndroplets accumulating onto a cover placed over warm food or windshields. In\nthese scenarios, determining the force of detachment is crucial to rationally\ndesign technologies. Despite much research, a quantitative theoretical\nframework for detachment force remains elusive. In response, we interrogated\nthe elemental droplet surface system via comprehensive laboratory and\ncomputational experiments. The results reveal that the Young Laplace equation\ncan be utilized to accurately predict the droplet detachment force. When\nchallenged against experiments with liquids of varying properties and droplet\nsizes, detaching from smooth and microtextured surfaces of wetting and non\nwetting chemical makeups, the predictions were in an excellent quantitative\nagreement. This study advances the current understanding of droplet physics and\nwill contribute to the rational development of technologies.",
        "positive": "On the Electronic Transport Mechanism in Conducting Polymer Nanofibers: Here, we present theoretical analysis of electron transport in polyaniline\nbased (PANi) nanofibers assuming the metalic state of the material. To build up\nthis theory we treat conducting polymers as a special kind of granular metals,\nand we apply the quantum theory of conduction in mesoscopic systems to describe\nthe transport between metallic-like granules. Our results show that the concept\nof resonance electron tunneling as the predominating mechanism providing charge\ntransport between the grains is supported with recent experiments on the\nelectrical characterization of single PANi nanofibers. By contacting the\nproposed theory with the experimental data we estimate some important\nparameters characterizing the electron transport in these materials. Also, we\ndiscuss the origin of rectifying features observed in current-voltage\ncharacteristics of fibers with varying cross-sectional areas."
    },
    {
        "anchor": "Convection and motion in 2-d embankments under cyclic boundary\n  conditions: The motion of grains in a 2d embankment under periodic horizontal forcing is\nstudied theoretically using Coulomb-type modelling. Periodic conditions are\nused to determined the inclination of the free surface. It is shown that no\nperiodic solution can be found in some domain of the bulk- and wall- friction\nparameters larger than 30 degrees. When a stable periodic solution exists, we\nshow that the finite amplitude of motion leads to generate a flow localised (i)\nat the free surface, (ii) near the bulldozer wall and (iii) in the yield band;\nthis may enforce a bulk convection too. At last, we argue why bulk convection\nis generated when the periodic solution is not stable. Results are compared to\nexperimental data. Pacs # : 5.40.-a ; 5.45.-a ; 45.70.-n ; 62.20.-x ; 83.50.V",
        "positive": "The Kirkwood-Riseman Polymer Model of Polymer Dynamics is Qualitatively\n  Correct: We use Brownian dynamics to show: For an isolated polymer coil in a shear\nfield, the Kirkwood-Riseman model for chain motion is qualitatively correct.\nUnder the same circumstances the Rouse model for chain motion is qualitatively\nincorrect. The models are qualitatively different. Kirkwood and Riseman say\npolymer coils in a shear field perform whole-body rotation; in the Rouse model\nrotation does not occur. Our simulations demonstrate that \\emph{in shear flow}:\nPolymer coils rotate. Rouse modes are cross-correlated. The amplitudes and\nrelaxation rates of Rouse modes depend on the shear rate. Rouse's calculation\nonly refers to a polymer coil in a quiescent fluid, where there is no viscous\ndissipation. Application of the Rouse model to a polymer coil undergoing shear\nis invalid."
    },
    {
        "anchor": "Non-monotonic dynamics in the onset of frictional slip: The transition from static to dynamic friction is often described as a\nfracture-like instantaneous slip. However, studies on slow sliding processes\naimed at understanding frictional instabilities and earthquakes report slow\nfriction transients that are usually explained by empirical rate-and-state\nformulations. We perform very slow ($\\sim nm/s$) macroscopic-scale sliding\nexperiments and show that the onset of frictional slip is governed by\ncontinuous non-monotonic dynamics originating from a competition between\ncontact aging and shear-induced rejuvenation. This allows to describe both our\nnon-monotonic dynamics and the simpler rate-and-state transients with a single\nevolution equation.",
        "positive": "Myosin-independent amoeboid cell motility: Mammalian cell polarization and motility are important processes involved in\nmany physiological and pathological phenomena, such as embryonic development,\nwound healing, and cancer metastasis. The traditional view of mammalian cell\nmotility suggests that molecular motors, adhesion, and cell deformation are all\nnecessary components for mammalian cell movement. However, experiments on the\nimmune cell system have shown that the inhibition of molecular motors does not\nsignificantly affect cell motility. We present a new theory and simulations\ndemonstrating that actin polymerization alone is sufficient to induce\nspontaneously cell polarity accompanied by the retrograde flow. These findings\nprovide a new understanding of the fundamental mechanisms of cell movement and\nat the same time provide a simple mechanism for cell motility in diverse\nconfigurations, e.g. on an adherent substrate, in a non-adherent matrix, or in\nliquids."
    },
    {
        "anchor": "Dynamics of osmotic flows: The paper presents a theoretical model that allows the dynamic description of\nosmotic flows through a semi-permeable interface. To depict the\nout-of-equilibrium transfer, the interface is represented by an energy barrier\nthat colloids have to overcome to be transmitted to the other side of the\nmembrane. This energy barrier thus represents the selectivity of the membrane.\nFurthermore, this energy barrier induces additional force terms in the momentum\nand the mass balances on the fluid and the colloids phases. Based on a two-\nfluid model, these forces can reproduce the physics of the osmotic flow without\nthe use of the semi-empirical laws of non-equilibrium thermodynamics. It is\nshown that a decrease in local pressure near the interface initiates osmosis.\nWhen these balance equations are solved in a transient mode, the dynamic of the\nosmotic flow can be described. The paper illustrates these potentialities by\nshowing the dynamic of an osmosis process occurring in the absence of\ntransmembrane pressure and both the dynamic of the reverse osmosis with a\nconstant flow through the membrane. A simulation reproducing the dynamic of the\nAbb\\'e Nollet experiment is presented. The role played by the colloid-membrane\ninteractions on the osmotic flow mechanism and on the counter osmotic pressure\nis analyzed and discussed in great details.",
        "positive": "Sequence randomness and polymer collapse transitions: Contrary to expectations based on Harris' criterion, chain disorder with\nfrustration can modify the universality class of scaling at the theta\ntransition of heteropolymers. This is shown for a model with random two-body\npotentials in 2D on the basis of exact enumeration and accurate Monte Carlo\nresults. When frustration grows beyond a certain finite threshold, the\ntemperature below which disorder becomes relevant coincides with the theta one\nand scaling exponents definitely start deviating from those valid for\nhomopolymers."
    },
    {
        "anchor": "Microrheology in tumbling nematics of 8CB liquid crystals: Particle tracking passive microrheology in 8CB liquid crystals is used to\nredefine the precessional motion of the orientation of nematic director in\nliquid crystals. Physical origin of tumbling director in presence of presmectic\nclusters under zero shear conditions is discussed. Different structural\nproperties (pure nematic phase, presmectic(smectic C and smectic A clusters))\nwere differentiated with characteristic dependence of $G'$ on $\\omega$ in the\nnematic phase of 8CB liquid crystals. Also, dynamic viscosity is observed with\na cross over between parallel and perpendicular components as the smectic A\nphase is approached.",
        "positive": "High concentration ferronematics in low magnetic fields: We investigated experimentally the magneto-optical and dielectric properties\nof magnetic-nanoparticle-doped nematic liquid crystals (ferronematics). Our\nstudies focus on the effect of the very small orienting bias magnetic field\n$B_{bias}$, and that of the nematic director pretilt at the boundary surfaces\nin our systems sensitive to low magnetic fields. Based on the results we assert\nthat $B_{bias}$ is not necessarily required for a detectable response to low\nmagnetic fields, and that the initial pretilt, as well as the aggregation of\nthe nanoparticles play an important (though not yet explored enough) role."
    },
    {
        "anchor": "Molecular and colloidal transport in bacterial cellulose hydrogels: Bacterial cellulose biofilms are complex networks of strong interwoven\nnanofibers that control transport and protect bacterial colonies in the film.\nDesign of diverse applications of bacterial cellulose films also relies on\nunderstanding and controlling transport through the fiber mesh, and transport\nsimulations of the films are most accurate when guided by experimental\ncharacterization of the structures and the resultant diffusion inside.\nDiffusion through such films is a function of their key microstructural length\nscales, determining how molecules, as well as particles and microorganisms,\npermeate them. We use microscopy to study the unique bacterial cellulose film\nstructure and quantify the mobility dynamics of various sizes of tracer\nparticles and macromolecules. Mobility is hindered within the films, as\nconfinement and local movement strongly depend on void size relative to\ndiffusing tracers. The biofilms have a naturally periodic structure of\nalternating dense and porous layers of nanofiber mesh, and we tune the\nmagnitude of the spacing via fermentation conditions. Micron-sized particles\ncan diffuse through the porous layers, but can not penetrate the dense layers.\nTracer mobility in the porous layers is isotropic, indicating a largely random\npore structure there. Molecular diffusion through the whole film is only\nslightly reduced by the structural tortuosity. Knowledge of transport\nvariations within bacterial cellulose networks can be used to guide design of\nsymbiotic cultures in these structures and enhance their use in applications\nbiomedical implants, wound dressings, lab-grown meat, and sensors.",
        "positive": "Plane shear flows of frictionless spheres: Kinetic theory and 3D\n  soft-sphere discrete element method simulations: We use existing 3D Discrete Element simulations of simple shear flows of\nspheres to evaluate the radial distribution function at contact that enables\nkinetic theory to correctly predict the pressure and the shear stress, for\ndifferent values of the collisional coefficient of restitution. Then, we\nperform 3D Discrete Element simulations of plane flows of frictionless,\ninelastic spheres, sheared between walls made bumpy by gluing particles in a\nregular array, at fixed average volume fraction and distance between the walls.\nThe results of the numerical simulations are used to derive boundary conditions\nappropriated in the cases of large and small bumpiness. Those boundary\nconditions are, then, employed to numerically integrate the differential\nequations of Extended Kinetic Theory, where the breaking of the molecular chaos\nassumption at volume fraction larger than 0.49 is taken into account in the\nexpression of the dissipation rate. We show that the Extended Kinetic Theory is\nin very good agreement with the numerical simulations, even for coefficients of\nrestitution as low as 0.50. When the bumpiness is increased, we observe that\nsome of the flowing particles are stuck in the gaps between the wall spheres.\nAs a consequence, the walls are more dissipative than expected, and the flows\nresemble simple shear flows, i.e., flows of rather constant volume fraction and\ngranular temperature."
    },
    {
        "anchor": "ESPResSo 4.0 -- An Extensible Software Package for Simulating Soft\n  Matter Systems: ESPResSo 4.0 is an extensible simulation package for research on soft matter.\nThis versatile molecular dynamics program was originally developed for\ncoarse-grained simulations of charged systems Limbach et al., Comput. Phys.\nCommun. 174, 704 (2006). The scope of the software has since broadened\nconsiderably: ESPResSo can now be used to simulate systems with length scales\nspanning from the molecular to the colloidal. Examples include, self-propelled\nparticles in active matter, membranes in biological systems, and the\naggregation of soot particles in process engineering. ESPResSo also includes\nsolvers for hydrodynamic and electrokinetic problems, both on the continuum and\non the explicit particle level. Since our last description of version 3.1\nArnold et al., Meshfree Methods for Partial Differential Equations VI, Lect.\nNotes Comput. Sci. Eng. 89, 1 (2013), the software has undergone considerable\nrestructuring. The biggest change is the replacement of the Tcl scripting\ninterface with a much more powerful Python interface. In addition, many new\nsimulation methods have been implemented. In this article, we highlight the\nchanges and improvements made to the interface and code, as well as the new\nsimulation techniques that enable a user of ESPResSo 4.0 to simulate physics\nthat is at the forefront of soft matter research.",
        "positive": "Free Energy Self-Averaging in Protein-Sized Random Heteropolymers: Current theories of heteropolymers are inherently macrpscopic, but are\napplied to folding proteins which are only mesoscopic. In these theories, one\ncomputes the averaged free energy over sequences, always assuming that it is\nself-averaging -- a property well-established only if a system with quenched\ndisorder is macroscopic. By enumerating the states and energies of compact 18,\n27, and 36mers on a simplified lattice model with an ensemble of random\nsequences, we test the validity of the self-averaging approximation. We find\nthat fluctuations in the free energy between sequences are weak, and that\nself-averaging is a valid approximation at the length scale of real proteins.\nThese results validate certain sequence design methods which can exponentially\nspeed up computational design and greatly simplify experimental realizations."
    },
    {
        "anchor": "Fragile-to-Strong Crossover, growing length scales, and dynamic\n  heterogeneity in Wigner Glasses: Colloidal particles, which are ubiquitous, have become ideal testing grounds\nfor the structural glass transition (SGT) theories. In these systems glassy\nbehavior is manifested as the density of the particles is increased. Thus, soft\ncolloidal particles with varying degree of softness capture diverse glass\nforming properties, observed normally in molecular glasses. By performing\nBrownian dynamics simulations for a binary mixture of micron-sized charged\ncolloidal suspensions, known to form Wigner glasses, we show that by tuning the\nsoftness of the potential, achievable by changing the monovalent salt\nconcentration, there is a continuous transition between fragile to strong\nbehavior. Remarkably, this is found in a system where the well characterized\npotential between the colloidal particles is isotropic. We also show that the\npredictions of the random first order transition (RFOT) theory quantitatively\ndescribes the universal features such as the growing correlation length,\n$\\xi\\sim (\\phi_K/\\phi - 1)^{-\\nu}$ with $\\nu = 2/3$ where $\\phi_K$, the\nanalogue of the Kauzmann temperature, depends on the salt concentration. As\nanticipated by the RFOT predictions, we establish a causal relationship between\nthe growing correlation length and a steep increase in the relaxation time and\ndynamic heterogeneity. The broad range of fragility observed in Wigner glasses\nis used to draw analogies with molecular glasses. The large variations in the\nfragility is found only when the temperature dependence of the viscosity is\nexamined for a large class of diverse glass forming materials. In sharp\ncontrast, this is vividly illustrated in a single system that can be\nexperimentally probed. Our work also shows that the RFOT predictions are\naccurate in describing the dynamics over the entire density range, regardless\nof the fragility of the glasses, implying that the physics describing the SGT\nis universal.",
        "positive": "Dynamics of ellipsoidal tracers in swimming algal suspensions: Enhanced diffusion of passive tracers immersed in active fluids is a\nuniversal feature of active fluids and has been extensively studied in recent\nyears. Similar to microrheology for equilibrium complex fluids, the unusual\nenhanced particle dynamics reveal intrinsic properties of active fluids.\nNevertheless, previous studies have shown that the translational dynamics of\nspherical tracers are qualitatively similar, independent of whether active\nparticles are pushers or pullers---the two fundamental classes of active\nfluids. Is it possible to distinguish pushers from pullers by simply imaging\nthe dynamics of passive tracers? Here, we investigated the diffusion of\nisolated ellipsoids in algal C. reinhardtii suspensions---a model for\npuller-type active fluids. In combination with our previous results on\npusher-type E. coli suspensions [Peng et al., Phys. Rev. Lett. 116, 068303\n(2016)], we showed that the dynamics of asymmetric tracers show a profound\ndifference in pushers and pullers due to their rotational degree of freedom.\nAlthough the laboratory-frame translation and rotation of ellipsoids are\nenhanced in both pushers and pullers, similar to spherical tracers, the\nanisotropic diffusion in the body frame of ellipsoids shows opposite trends in\nthe two classes of active fluids. An ellipsoid diffuses fastest along its major\naxis when immersed in pullers, whereas it diffuses slowest along the major axis\nin pushers. This striking difference can be qualitatively explained using a\nsimple hydrodynamic model. In addition, our study on algal suspensions reveals\nthat the influence of the near-field advection of algal swimming flows on the\ntranslation and rotation of ellipsoids shows different ranges and strengths.\nOur work provides not only new insights into universal organizing principles of\nactive fluids, but also a convenient tool for detecting the class of active\nparticles."
    },
    {
        "anchor": "Arrest stress of uniformly sheared wet granular matter: We conduct extensive independent numerical experiments considering\nfrictionless disks without internal degrees of freedom (rotation etc.) in two\ndimensions. We report here that for a large range of the packing fractions\nbelow random-close packing, all components of the stress tensor of wet granular\nmaterials remain finite in the limit of zero shear rate. This is direct\nevidence for a fluid-to-solid arrest transition. The offset value of the shear\nstress characterizes plastic deformation of the arrested state {which\ncorresponds to {\\em dynamic yield stress} of the system}. {Based on an\nanalytical line of argument, we propose that the mean number of capillary\nbridges per particle, $\\nu$, follows a non-trivial dependence on the packing\nfraction, $\\phi$, and the capillary energy, $\\vareps$. Most noticeably, we show\nthat $\\nu$ is a generic and universal quantity which does not depend on the\ndriving protocol.} Using this universal quantity, we calculate the arrest\nstress, $\\sigma_a$, analytically based on a balance of the energy injection\nrate due to the external force driving the flow and the dissipation rate\naccounting for the rupture of capillary bridges. The resulting prediction of\n$\\sigma_a$ is a non-linear function of the packing fraction $\\phi$, and the\ncapillary energy $\\vareps$. This formula provides an excellent, parameter-free\nprediction of the numerical data. Corrections to the theory for small and large\npacking fractions are connected to the emergence of shear bands and of\ncontributions to the stress from repulsive particle interactions, respectively.",
        "positive": "Taxis of Artificial Swimmers in a Spatio-Temporally Modulated Activation\n  Medium: Contrary to microbial taxis, where a tactic response to external stimuli is\ncontrolled by complex chemical pathways acting like sensor-actuator loops,\ntaxis of artificial microswimmers is a purely stochastic effect associated with\na non-uniform activation of the particles' self-propulsion. We study the tactic\nresponse of such swimmers in a spatio-temporally modulated activating medium by\nmeans of both numerical and analytical techniques. In the opposite limits of\nvery fast and very slow rotational particle dynamics, we obtain analytic\napproximations that closely reproduce the numerical description. A swimmer\ndrifts on average either parallel or anti-parallel to the propagation direction\nof the activating pulses, depending on their speed and width. The drift in line\nwith the pulses is solely determined by the finite persistence length of the\nactive Brownian motion performed by the swimmer, whereas the drift in the\nopposite direction results from the combination of ballistic and diffusive\nproperties of the swimmer's dynamics."
    },
    {
        "anchor": "Filling and wetting transitions of nematic liquid crystals on sinusoidal\n  substrates: Close to sinusoidal substrates, simple fluids may undergo a filling\ntransition, in which the fluid passes from a dry to a filled state, where the\ninterface remains unbent but bound to the substrate. Increasing the surface\nfield, the interface unbinds and a wetting transition occurs. We show that this\ndouble-transition sequence may be strongly modified in the case of ordered\nfluids, such as nematic liquid crystals. Depending on the preferred orientation\nof the nematic molecules at the structured substrate and at the\nisotropic-nematic interface, the filling transition may not exist, and the\nfluid passes directly from a dry to a complete-wet state, with the interface\nfar from the substrate. More interestingly, in other situations, the complete\nwetting transition may be prevented, and the fluid passes from a dry to a\nfilled state, and remains in this configuration, with the interface always\nattached to the substrate, even for very large surface fields. Both transitions\nare only observed for a same substrate in a narrow range of amplitudes.",
        "positive": "Surface Tension of Aqueous Electrolyte Solutions. Thermomechanical\n  Approach: We utilize a thermomechanical approach that involves a derivation of the\nstress tensor from the thermodynamic potential of an inhomogeneous fluid. This\nmethod allows us to determine the surface tension of aqueous electrolyte\nsolutions in contact with non-polar dielectric media. To obtain the surface\ntension, we calculate both the normal and tangential pressures using the\ncomponents of the derived stress tensor. This tensor was recently obtained by\nus [Y. A. Budkov and P. E. Brandyshev, The Journal of Chemical Physics 159\n(2023)] within the framework of Wang's variational field theory. By employing\nthis approach, in the linear approximation, we have derived an analytical\nexpression for surface tension. At low ionic concentrations, the expression\nrepresents the classical Onsager-Samaras limiting law. By utilizing only one\nfitting parameter, which relates to the affinity of anions to the dielectric\nboundary, we estimate various experimental data pertaining to the surface\ntension of aqueous electrolyte solutions. This estimation applies to both the\nsolution-air and solution-dodecane interface, covering a wide range of\nelectrolyte concentrations."
    },
    {
        "anchor": "Non-uniqueness of late-time scaling states in spinodal decomposition: In this letter we show that the late-time scaling state in spinodal\ndecomposition is not unique. We performed lattice Boltzmann simulations of the\nphase-ordering of a 50%-50% binary mixture using as initial conditions for the\nphase-ordering both a symmetric morphology that was created by symmetric\nspinodal decomposition and a morphology of one phase dispersed in the other,\ncreated by viscoelastic spinodal decomposition. We found two different growth\nlaws at late times, although both simulations differ only in the early time\ndynamics. The new scaling state consists of dispersed droplets. The growth law\nassociated with this scaling state is consistent with a $L\\sim t^{1/2}$ scaling\nlaw.",
        "positive": "Comment on \"Influence of Noise on Force Measurement\" [arXiv:1004.0874]: In a recent Letter [arXiv:1004.0874], Volpe et al. describe experiments on a\ncolloidal particle near a wall in the presence of a gravitational field for\nwhich they study the influence of noise on the measurement of force. Their\ncentral result is a striking discrepancy between the forces derived from\nexperimental drift measurements via their Eq. (1), and from the equilibrium\ndistribution. From this discrepancy they infer the stochastic calculus realised\nin the system.\n  We comment, however: (a) that Eq. (1) does not hold for space-dependent\ndiffusion, and corrections should be introduced; and (b) that the \"force\"\nderived from the drift need not coincide with the \"force\" obtained from the\nequilibrium distribution."
    },
    {
        "anchor": "Planar and non-planar solidification Planar and non-planar\n  solidification of optically organized smectic films: We present in this letter an original freezing process yielding remarkably\nhomogeneous films of chiral smectics. This optical homogeneity is observed on\nplanar films as well as on films exhibiting various complex three-dimensional\nshapes.",
        "positive": "Constant speed penetration into granular materials: drag forces from the\n  quasistatic to inertial regime: Predicting the force exerted on an object as it penetrates a granular medium\nis of interest in engineering, locomotive, and geotechnical applications.\nCurrent models of granular drag, however, vary widely in applicability and\nparameterization, and the physical origin of the granular resistive force\nitself is a subject of debate. Here we perform constant speed penetration\nexperiments, combined with calibrated, large-scale molecular dynamics\nsimulations, at velocities up to 2 m/s to test the effect of impact velocity on\nthe depth dependent `hydrostatic' drag force. We discover that the evolution of\nthe granular flow field around an intruder regulates the presence of depth\ndependent drag forces. In addition, we find that the observed linear depth\ndependence is commensurate with the mass of flowing grains. These results\nsuggest that, as the impact speed increases beyond the quasistatic regime, the\ndepth dependent drag term becomes intertwined with inertial effects."
    },
    {
        "anchor": "A Comment on the Scale Length Validity of the Position Dependent\n  Diffusion Coefficient Representation of Structural Heterogeneity: Experimental studies of the variation of the mean square displacement (MSD)\nof a particle in a confined colloid suspension that exhibits density variations\non the scale length of the particle diameter are not in agreement with the\nprediction that the spatial variation in MSD should mimic the spatial variation\nin density. The predicted behavior is derived from the expectation that the MSD\nof a particle depends on the system density and the assumption that the force\nacting on a particle is a point function of position. The experimental data\ncome from studies of the MSDs of particles in narrow ribbon channels and\nbetween narrowly spaced parallel plates, and from new data, reported herein, of\nthe radial and azimuthal MSDs of a colloid particle in a dense colloid\nsuspension confined to a small circular cavity. In each of these geometries a\ndense colloid suspension exhibits pronounced density oscillations with spacing\nof a particle diameter. We remove the discrepancy between prediction and\nexperiment using the Fisher-Methfessel interpretation of how local equilibrium\nin an inhomogeneous system is maintained to argue that the force acting on a\nparticle is delocalized over a volume with radius equal to a particle diameter.\nOur interpretation has relevance to the relationship between the scale of\ninhomogeneity and the utility of translation of the particle MSD into a\nposition dependent diffusion coefficient, and to the use of a spatially\ndependent diffusion coefficient to describe mass transport in a heterogeneous\nsystem.",
        "positive": "Effect of Counterion Size on Polyelectrolyte Conformations and\n  Thermodynamics: We present a theoretical model to study the effect of counterion size on the\neffective charge, size, and thermodynamic behavior of a single, isolated, and\nflexible polyelectrolyte (PE) chain. We analyze how altering counterion size\nmodifies the energy and entropy contributions to the system, including the\nion-pair free energy, excluded volume interactions, entropy of free and\ncondensed ions, and dipolar attraction among monomer-counterion pairs, which\nresult in competing effects challenging intuitive predictions. The PE self\nenergy is calculated using Edwards-Muthukumar Hamiltonian, considering a\nGaussian monomer distribution for the PE. The condensed ions are assumed\nconfined within a cylindrical volume around the PE backbone. The dipolar and\nexcluded volume interactions are described by the second and third virial\ncoefficients. Assumption of freely-rotating dipoles results in a first-order\ncoil-globule transition of the PE chain. A more realistic weaker dipolar\nattraction, parameterized in our theory, shifts it to a second-order continuous\ntransition. We calculate the size scaling-exponent of the PE and find exponents\naccording to the relative dominance of the electrostatic, excluded volume, or\ndipolar effects. We further identify the entropy- and energy-driven regimes of\nthe effective charge and conformation of the PE, highlighting the interplay of\nfree ion entropy and ion-pair energy with varying electrostatic strengths. The\ncrossover strength, dependent on the counterion size, indicates that\ndiminishing sizes favor counterion condensation at the expense of free ion\nentropy. The predictions of the model are consistent with trends in\nsimulations, and generalize findings of the point-like counterion theories."
    },
    {
        "anchor": "Buckling of Spherical Capsules: We investigate buckling of soft elastic capsules under negative pressure or\nfor reduced capsule volume. Based on nonlinear shell theory and the assumption\nof a hyperelastic capsule membrane, shape equations for axisymmetric and\ninitially spherical capsules are derived and solved numerically. A rich\nbifurcation behavior is found, which is presented in terms of bifurcation\ndiagrams. The energetically preferred stable configuration is deduced from a\nleast-energy principle both for prescribed volume and prescribed pressure. We\nfind that buckled shapes are energetically favorable already at smaller\nnegative pressures and larger critical volumes than predicted by the classical\nbuckling instability. By preventing self-intersection for strongly reduced\nvolume, we obtain a complete picture of the buckling process and can follow the\nshape from the initial undeformed state through the buckling instability into\nthe fully collapsed state. Interestingly, the sequences of bifurcations and\nstable capsule shapes differ for prescribed volume and prescribed pressure. In\nthe buckled state, we find a relation between curvatures at the indentation rim\nand the bending modulus, which can be used to determine elastic moduli from\nexperimental shape analysis.",
        "positive": "Liquid-Hextic-Solid Phase Transition of a Hard-Core Lattice Gas with\n  Third Neighbor Exclusion: The determination of phase behavior and, in particular, the nature of phase\ntransitions in two-dimensional systems is often clouded by finite size effects\nand by access to the appropriate thermodynamic regime. We address these issues\nusing an alternative route to deriving the equation of state of a\ntwo-dimensional hard-core particle system, based on kinetic arguments and the\nGibbs adsorption isotherm, by use of the random sequential adsorption with\nsurface diffusion (RSAD) model. Insight into coexistence regions and phase\ntransitions is obtained through direct visualization of the system at any\nfractional surface coverage via local bond orientation order. The analysis of\nthe bond orientation correlation function for each individual configuration\nconfirms that first-order phase transition occurs in a two-step\nliquid-hexatic-solid transition at high surface coverage."
    },
    {
        "anchor": "Distinguishing Advective and Powered Motion in Self-Propelled Colloids: Self-powered motion in catalytic colloidal particles provides a compelling\nexample of active matter, i.e. systems that engage in single-particle and\ncollective behavior far from equilibrium. The long-time, long-distance behavior\nof such systems is of particular interest, since it connects their individual\nmicro-scale behavior to macro-scale phenomena. In such analyses, it is\nimportant to distinguish motion due to subtle advective effects -- which also\nhas long time scales and length scales -- from phenomena that derive from\nintrinsically powered motion. Here, we develop a methodology to analyze the\nstatistical properties of the translational and rotational motions of powered\ncolloids to distinguish, for example, active chemotaxis from passive advection\nby bulk flow.",
        "positive": "Evaluation of phenomenological one-phase criteria for the melting and\n  freezing of softly repulsive particles: We test the validity of some widely used phenomenological criteria for the\nlocalization of the fluid-solid transition thresholds against the phase\ndiagrams of particles interacting through the exp-6, inverse-power-law, and\nGaussian potentials. We find that one-phase rules give, on the whole, reliable\nestimates of freezing/melting points. The agreement is ordinarily better for a\nface-centered-cubic solid than for a body-centered-cubic crystal, even more so\nin the presence of a pressure-driven re-entrant transition of the solid into a\ndenser fluid phase, as found in the Gaussian-core model."
    },
    {
        "anchor": "Adhesion of membranes via receptor-ligand complexes: Domain formation,\n  binding cooperativity, and active processes: Cell membranes interact via anchored receptor and ligand molecules. Central\nquestions on cell adhesion concern the binding affinity of these\nmembrane-anchored molecules, the mechanisms leading to the receptor-ligand\ndomains observed during adhesion, and the role of cytoskeletal and other active\nprocesses. In this review, these questions are addressed from a theoretical\nperspective. We focus on models in which the membranes are described as elastic\nsheets, and the receptors and ligands as anchored molecules. In these models,\nthe thermal membrane roughness on the nanometer scale leads to a cooperative\nbinding of anchored receptor and ligand molecules, since the receptor-ligand\nbinding smoothens out the membranes and facilitates the formation of additional\nbonds. Patterns of receptor domains observed in Monte Carlo simulations point\ntowards a joint role of spontaneous and active processes in cell adhesion. The\ninteractions mediated by the receptors and ligand molecules can be\ncharacterized by effective membrane adhesion potentials that depend on the\nconcentrations and binding energies of the molecules.",
        "positive": "Shape matters: A Brownian microswimmer in a channel: We consider the active Brownian particle (ABP) model for a two-dimensional\nmicroswimmer with fixed speed, whose direction of swimming changes according to\na Brownian process. The probability density for the swimmer evolves according\nto a Fokker-Planck equation defined on the configuration space, whose structure\ndepends on the swimmer's shape, center of rotation and domain of swimming. We\nenforce zero probability flux at the boundaries of configuration space. We\nderive a reduced equation for a swimmer in an infinite channel, in the limit of\nsmall rotational diffusivity, and find that the invariant density depends\nstrongly on the swimmer's precise shape and center of rotation. We also give a\nformula for the mean reversal time: the expected time taken for a swimmer to\ncompletely reverse direction in the channel. Using homogenization theory, we\nfind an expression for the effective longitudinal diffusivity of a swimmer in\nthe channel, and show that it is bounded by the mean reversal time."
    },
    {
        "anchor": "Molecular structure of the Discotic Liquid Crystalline Phase of\n  Hexa-peri-Hexabenzocoronene/Oligothiophene Hybrid and their Charge Transport\n  properties: Using atomistic molecular dynamics simulation we study the discotic columnar\nliquid crystalline (LC) phases formed by a new organic compound having\nHexa-peri-Hexabenzocoronene (HBC) core with six pendant oligothiophene units\nrecently synthesized by Nan Hu et al. (N. Hu, R. Shao, Y. Shen, D. Chen, N. A.\nClark and D. M. Walba, Adv. Mater. 26, 2066, 2014). This HBC core based LC\nphase was shown to have electric field responsive behavior and has important\napplication in organic electronics. Our simulation results confirm the\nhexagonal arrangement of columnar LC phase with a lattice spacing consistent\nwith that obtained from small angle X-ray diffraction data. We have also\ncalculated various positional and orientational correlation functions to\ncharacterize the ordering of the molecules in the columnar arrangement. The\nmolecules in a column are arranged with an average twist of 25 degrees having\nan average inter-molecular separation of ~5 {\\AA}. Interestingly, we find an\noverall tilt angle of 43 degrees between the columnar axis and HBC core. We\nalso simulate the charge transport through this columnar phase and report the\nnumerical value of charge carrier mobility for this liquid crystal phase. The\ncharge carrier mobility is strongly influenced by the twist angle and average\nspacing of the molecules in the column.",
        "positive": "The thermal Casimir effect in lipid bilayer tubules: We calculate the thermal Casimir effect for a dielectric tube of radius $R$\nand thickness delta formed from a membrane in water. The method uses a\nfield-theoretic approach in the grand canonical ensemble. The leading\ncontribution to the Casimir free energy behaves as -k_BTL kappa_C/R giving rise\nto an attractive force which tends to contract the tube. We find that kappa_C ~\n0.3 for the case of typical lipid membrane t-tubules. We conclude that except\nin the case of a very soft membrane this force is insufficient to stabilize\nsuch tubes against the bending stress which tends to increase the radius."
    },
    {
        "anchor": "Self Healing Interconnects with a Near Plastically Stretchable Heal: Flexible electronic systems such as roll up displays, wearable devices etc.\npromise exciting possibilities that could change the way humans interact with\nthe environment. However, they suffer from poor reliability of interconnects\nand devices. Interconnects on flex are prone to open circuit failures due to\nmechanical stress, electrostatic discharge and environmental degradation.\nPassive approaches such as the use of stretchable conductors and novel\ngeometries improve their response to mechanical stress but cannot salvage the\ninterconnect if a fault were to occur. Active approaches using self healing\ntechniques can repair a fault and have been demonstrated using methods that\neither use relatively rare materials, change conventional interconnect\nfabrication processes, only address faults due to mechanical stress or do not\npermit stretching. In this work we discuss a self healing technique that\novercomes these limitations and demonstrate heals having metallic conductivity\nand nearly plastic stretchability. This is achieved using a dispersion of\nconductive particles in an insulating fluid encapsulated over the interconnect.\nHealing is automatically triggered by the electric field appearing in the open\ngap of a failed interconnect, irrespective of the cause of failure. The field\npolarizes the conductive particles causing them aggregate and chain up to\nbridge the gap and repair the fault. Using copper-silicone oil dispersions, we\nshow self healing interconnects with the stretchable heal having conductivity\nof about $5 \\times 10^{5}$ Sm and allowing strains from 12 to 60. Previously,\nstretchable interconnects used materials other than copper. Here we effectively\nshow self healing, stretchable copper. This work promises high speed, self\nhealing and stretchable interconnects on flex thereby improving system\nreliability.",
        "positive": "Beyond Tanner's Law: Crossover between Spreading Regimes of a Viscous\n  Droplet on an Identical Film: We present results on the leveling of polymer microdroplets on thin films\nprepared from the same material. In particular, we explore the crossover from a\ndroplet spreading on an infinitesimally thin film (Tanner's law regime) to that\nof a droplet leveling on a film thicker than the droplet itself. In both\nregimes, the droplet's excess surface area decreases towards the equilibrium\nconfiguration of a flat liquid film, but with a different power law in time.\nAdditionally, the characteristic leveling time depends on molecular properties,\nthe size of the droplet, and the thickness of the underlying film. Flow within\nthe film makes this system fundamentally different from a droplet spreading on\na solid surface. We thus develop a theoretical model based on thin film\nhydrodynamics that quantitatively describes the observed crossover between the\ntwo leveling regimes."
    },
    {
        "anchor": "Microscopic precursors of failure in soft matter: The mechanical properties of soft matter are of great importance in countless\napplications, in addition of being an active field of academic research. Given\nthe relative ease with which soft materials can be deformed, their non-linear\nbehavior is of particular relevance. Large loads eventually result in material\nfailure. In this Perspective article, we discuss recent work aiming at\ndetecting precursors of failure by scrutinizing the microscopic structure and\ndynamics of soft systems under various conditions of loading. In particular, we\nshow that the microscopic dynamics is a powerful indicator of the ultimate fate\nof soft materials, capable of unveiling precursors of failure up to thousands\nof seconds before any macroscopic sign of weakening.",
        "positive": "Impact of attractive interactions on the rheology of dense athermal\n  particles: Using numerical simulations, the rheological response of an athermal assembly\nof soft particles with tunable attractive interactions is studied in the\nvicinity of jamming. At small attractions, a fragile solid develops and a\nfinite yield stress is measured. Moreover, the measured flow curves have\nunstable regimes, which lead to persistent shearbanding. These features are\nrationalized by establishing a link between the rheology and the inter-particle\nconnectivity, which also provides a minimal model to describe the flow curves."
    },
    {
        "anchor": "Salt effects on the mechanical properties of ionic conductive polymer: a\n  molecular dynamics study: Functoinal polymers can be used as electrolyte and binder materials in\nsolid-state batteries. This often requires performance targets in terms of both\ntransport and mechanical properties. In this work, a model ionic conductive\npolymer system, i.e., poly(ethylene oxide)-LiTFSI, was used to study the impact\nof salt concentrations on mechanical properties, including different types of\nelastic moduli and the visoelasticity with both non-equilibrium and equilibrium\nmolecular dynamics simulations. We found an encouragingly good agreement\nbetween experiments and simulations regarding the Young's modulus, bulk modulus\nand viscosity. In addition, we identified an intermediate salt concentration at\nwhich the system shows high ionic conductivity, high Young's modulus and short\nelastic restoration time. Therefore, this study laid down the groundwork for\ninvestigating ionic conductive polymer binders with self-healing functionality\nfrom molecular dynamics simulations.",
        "positive": "Viscoelastic acoustic response of layered polymer films at fluid-solid\n  interfaces: Continuum mechanics approach: We have derived the general solution of a wave equation describing the\ndynamics of two-layere viscoelastic polymer materials of arbitrary thickness\ndeposited on solid (quartz) surfaces in a fluid environment. Within the Voight\nmodel of viscoelastic element, we calculate the acoustic response of the system\nto an applied shear stress, i.e. we find the shift of the quartz generator\nresonance frequency and of the dissipation factor, and show that it strongly\ndepends on the viscous loading of the adsorbed layers and on the shear storage\nand loss moduli of the overlayers. These results can readily be applied to\nquartz crystal acoustical measurements of the viscoelasticity of polymers,\nwhich conserve their shape under the shear deformations and do not flow, and\nlayered structures such as protein films adsorbed from solution onto the\nsurface of self-assembled monolayres."
    },
    {
        "anchor": "Short-time critical dynamics and universality on a two-dimensional\n  Triangular Lattice: Critical scaling and universality in short-time dynamics for spin models on a\ntwo-dimensional triangular lattice are investigated by using Monte Carlo\nsimulation. Emphasis is placed on the dynamic evolution from fully ordered\ninitialstates to show that universal scaling exists already in the short-time\nregime in form of power-law behavior of the magnetization and Binder cumulant.\nThe results measured for the dynamic and static critical exponents, $\\theta$,\n$z$, $\\beta$ and $\\nu$, confirm explicitly that the Potts models on the\ntriangular lattice and square lattice belong to the same universality class.\nOur critical scaling analysis strongly suggests that the simulation for the\ndynamic relaxation can be used to determine numerically the universality.",
        "positive": "Caging dynamics in a granular fluid: We report an experimental investigation of the caging motion in a uniformly\nheated granular fluid, for a wide range of filling fractions, $\\phi$. At low\n$\\phi$ the classic diffusive behavior of a fluid is observed. However, as\n$\\phi$ is increased, temporary cages develop and particles become increasingly\ntrapped by their neighbors. We statistically analyze particle trajectories and\nobserve a number of robust features typically associated with dense molecular\nliquids and colloids. Even though our monodisperse and quasi-2D system is known\nto not exhibit a glass transition, we still observe many of the precursors\nusually associated with glassy dynamics. We speculate that this is due to a\nprocess of structural arrest provided, in our case, by the presence of\ncrystallization."
    },
    {
        "anchor": "Kinetic Arrest Originating in Competition between\\linebreak Attractive\n  Interaction and Packing Force: We discuss the situation where attractive and repulsive portions of the\ninter-particle potential both contribute significantly to glass formation. We\nintroduce the square-well potential as prototypical model for this situation,\nand {\\it reject} the Baxter as a useful model for comparison to experiment on\nglasses, based on our treatment within mode coupling theory. We present\nexplicit results for various well-widths, and show that, for narrow wells,\nthere is a useful analytical formula that would be suitable for experimentalist\nworking in the field of colloidal science. We raise the question as to whether,\nin a more exact treatment, the sticky sphere limit might have an infinite glass\ntransition temperature, or a high but finite one.",
        "positive": "Periodic ordering of clusters and stripes in a two-dimensional lattice\n  model. II. Results of Monte Carlo simulation: The triangular lattice model with nearest-neighbor attraction and\nthird-neighbor repulsion, introduced in [J. Pekalski, A. Ciach and N. G.\nAlmarza, arXiv:1401.0801 [cond-mat.soft]] is studied by Monte Carlo simulation.\nIntroduction of appropriate order parameters allowed us to construct a phase\ndiagram, where different phases with patterns made of clusters, bubbles or\nstripes are thermodynamically stable. We observe, in particular, two distinct\nlamellar phases - the less ordered one with global orientational order and the\nmore ordered one with both orientational and translational order. Our results\nconcern spontaneous pattern formation on solid surfaces, fluid interfaces or\nmembranes that is driven by competing interactions between adsorbing particles\nor molecules."
    },
    {
        "anchor": "Analytical modeling of micelle growth. 4. Molecular thermodynamics of\n  wormlike micelles from ionic surfactants: theory vs. experiment: Hypotheses: The aggregation number and length of spherocylindrical (rodlike,\nwormlike) micelles in solutions of an ionic surfactant and salt can be\npredicted knowing the molecular parameters and the input concentrations of the\nspecies. This can be achieved by upgrading the quantitative molecular\nthermodynamic model from the previous parts of this series with an expression\nfor the electrostatic component of micelle scission energy that is the excess\nfree energy of the spherical endcaps with respect to the cylindrical part of\nthe micelle. Theory: The thermodynamics of micellization is extended to the\ncase of multicomponent system, which may contain several surfactants (both\nionic and nonionic) and salts, taking into account the effect of counterion\nbinding in the Stern layer on the micellar surface. Furthermore, the\nconsiderations are focused on a system that consists of single ionic surfactant\nplus salt. Findings: Excellent agreement was achieved between the theoretical\nmodel and experimental data for wormlike micelles from anionic and cationic\nsurfactants at various concentrations of salt and temperatures. In accord with\nthe experimental observations, at high salt concentrations, the model predicts\nloss of chemical equilibrium between the endcaps and cylindrical part of the\nwormlike micelles, which implies transition to self-assemblies of other, e.g.\nbranched, morphology or the onset of crystallization and phase separation.",
        "positive": "Comparison of Single-Ion Molecular Dynamics in Common Solvents: Laying a basis for molecularly specific theory for the mobilities of ions in\nsolutions of practical interest, we report a broad survey of velocity\nautocorrelation functions (VACFs) of Li$^+$ and PF$_6{}^-$ ions in water,\nethylene carbonate, propylene carbonate, and acetonitrile solutions. We extract\nthe memory function, $\\gamma(t)$, which characterizes the random forces\ngoverning the mobilities of ions. We provide comparisons, controlling for\nelectrolyte concentration and ion-pairing, for van~der~Waals attractive\ninteractions and solvent molecular characteristics. For the heavier ion\n(PF$_6{}^-$), velocity relaxations are all similar: negative tail relaxations\nfor the VACF and a clear second relaxation for $\\gamma\\left(t\\right)$, observed\npreviously also for other molecular ions and with \\emph{n}-pentanol as solvent.\nFor the light Li$^+$ ion, short time-scale oscillatory behavior masks simple,\nlonger time-scale relaxation of $\\gamma\\left(t\\right)$. But the corresponding\nanalysis of the \\emph{solventberg} Li$^+\\left(\\mathrm{H}_2\\mathrm{O}\\right)_4$\ndoes conform to the standard picture set by all the PF$_6{}^-$ results."
    },
    {
        "anchor": "Transverse transport of solutes between co-flowing pressure-driven\n  streams for microfluidic studies of diffusion/reaction processes: We consider a situation commonly encountered in microfluidics: two streams of\nmiscible liquids are brought at a junction to flow side by side within a\nmicrochannel, allowing solutes to diffuse from one stream to the other and\npossibly react. We focus on two model problems: (i) the transverse transport of\na single solute from a stream into the adjacent one, (ii) the transport of the\nproduct of a diffusion-controlled chemical reaction between solutes originating\nfrom the two streams. Our description is made general through a\nnon-dimensionalized formulation that incorporates both the parabolic Poiseuille\nvelocity profile along the channel and thermal diffusion in the transverse\ndirection. Numerical analysis over a wide range of the streamwise coordinate\n$x$ reveal different regimes. Close to the top and the bottom walls of the\nmicrochannel, the extent of the diffusive zone follows three distinct power law\nregimes as $x$ is increased, characterized respectively by the exponents 1/2,\n1/3 and 1/2. Simple analytical arguments are proposed to account for these\nresults.",
        "positive": "Micellization of Sliding Polymer Surfactants: Following up a recent paper on grafted sliding polymer layers (Macromolecules\n2005, 38, 1434-1441), we investigated the influence of the sliding degree of\nfreedom on the self-assembly of sliding polymeric surfactants that can be\nobtained by complexation of polymers with cyclodextrins. In contrast to the\nmicelles of quenched block copolymer surfactants, the free energy of micelles\nof sliding surfactants can have two minima: the first corresponding to small\nmicelles with symmetric arm lengths, and the second corresponding to large\nmicelles with asymmetric arm lengths. The relative sizes and concentrations of\nsmall and large micelles in the solution depend on the molecular parameters of\nthe system. The appearance of small micelles drastically reduces the kinetic\nbarrier signifying the fast formation of equilibrium micelles."
    },
    {
        "anchor": "Softening of Granular Packings with Dynamic Forcing: We perform numerical simulations of a two-dimensional bidisperse granular\npacking subjected to both a static confining pressure and a sinusoidal dynamic\nforcing applied by a wall on one edge of the packing. We measure the response\nexperienced by a wall on the opposite edge of the packing and obtain the\nresonant frequency of the packing as the static or dynamic pressures are\nvaried. Under increasing static pressure, the resonant frequency increases,\nindicating a velocity increase of elastic waves propagating through the\npacking. In contrast, when the dynamic amplitude is increased for fixed static\npressure, the resonant frequency decreases, indicating a decrease in the wave\nvelocity. This occurs both for compressional and for shear dynamic forcing, and\nis in agreement with experimental results. We find that the average contact\nnumber $Z_c$ at the resonant frequency decreases with increasing dynamic\namplitude, indicating that the elastic softening of the packing is associated\nwith a reduced number of grain-grain contacts through which the elastic waves\ncan travel. We image the excitations created in the packing and show that there\nare localized disturbances or soft spots that become more prevalent with\nincreasing dynamic amplitude. Our results are in agreement with experiments on\nglass bead packings and earth materials such as sandstone and granite, and may\nbe relevant to the decrease in elastic wave velocities that has been observed\nto occur near fault zones after strong earthquakes, in surficial sediments\nduring strong ground motion, and in structures during earthquake excitation.",
        "positive": "Distinct dynamical and structural properties of a core-softened fluid\n  when confined between fluctuating and fixed walls: We study the influence of mobility of the confining media in the structural\nand dynamical properties of a core-softened fluid under confinement. The fluid\nis modeled using a two-length scale potential, which reproduces in bulk the\nanomalous behavior observed in water. We perform simulations in the $NVT$\nensemble with fixed flat walls and in the $NpT$ ensemble using a fluctuating\nwall control of pressure to study how the fluid behavior is affected by fixed\nand non-fixed walls. Our results indicate that the fluid dynamical and\nstructural properties are strongly affected by the wall mobility. The distinct\nobserved behavior are explained in the framework of the two length scale\npotential."
    },
    {
        "anchor": "Topology Restricts Quasidegeneracy in Sheared Square Colloidal Ice: Recovery of ground-state degeneracy in two-dimensional square ice is a\nsignificant challenge in the field of geometric frustration with far-reaching\nfundamental implications, such as realization of vertex models and\nunderstanding the effect of dimensionality reduction. We combine experiments,\ntheory, and numerical simulations to demonstrate that sheared square colloidal\nice partially recovers the ground-state degeneracy for a wide range of field\nstrengths and lattice shear angles. Our method opens an avenue to engineer a\nnovel class of frustrated micro- and nano-structures based on sheared magnetic\nlattices in a wide range of soft- and condensed-matter systems.",
        "positive": "Capillary bridging and long-range attractive forces in a mean-field\n  approach: When a mixture is confined, one of the phases can condense out. This\ncondensate, which is otherwise metastable in the bulk, is stabilized by the\npresence of surfaces. In a sphere-plane geometry, routinely used in atomic\nforce microscope (AFM) and surface force apparatus (SFA), it can form a bridge\nconnecting the surfaces. The pressure drop in the bridge gives rise to\nadditional long-range attractive forces between them.\n  Minimizing the free energy of a binary mixture we obtain the force-distance\ncurves as well as the structural phase diagram of the configuration with the\nbridge. Numerical results predict a discontinuous transition between the states\nwith and without the bridge and linear force-distance curves with hysteresis.\n  We also show that similar phenomenon can be observed in a number of different\nsystems, e.g. liquid crystals and polymer mixtures."
    },
    {
        "anchor": "Temperature-Modulated Photomechanical Actuation of Photoactive Liquid\n  Crystal Elastomers: Photoactive liquid crystal elastomers are polymer networks of liquid crystal\nmesogens embedded with chromophores like azobenzene. They undergo large\ndeformation when illuminated by light of a certain wavelength through\nphotochemical reaction, inspiring exciting new applications. However, despite\nthe recent progresses in both the experiment and theory of these materials, the\nfundamental understanding of the temperature effect on their photomechanical\nactuation through various molecular-to-mesoscale processes have remained\nlargely unexplored. This paper constructs a theoretical model to investigate\nthis temperature-modulated photomechanical actuation, by integrating different\ntemperature-dependent processes into a continuum framework. The model studies a\nspecial working condition where the material is subjected to a uniaxial tensile\nload, a prescribed temperature, and a polarized light illumination. We explore\nthe free energy landscape of the system and the uniaxial stress-stretch\nresponses under various conditions. We exploit the coupling between individual\ncontrols of temperature and light in a single photomechanical actuation for\nseveral working scenarios, including the temperature-modulated photomechanical\nsnap-through instability, specific work, and blocking stress. We study the\neffect of the temperature-dependent backward isomerization of chromophores on\nthe photomechanical actuation. These results are hoped to motivate future\nfundamental studies and new applications of various photomechanical material\nsystems.",
        "positive": "Packing of elastic wires in spherical cavities: We investigate the morphologies and maximum packing density of thin wires\npacked into spherical cavities. Using simulations and experiments, we find that\nordered as well as disordered structures emerge, depending on the amount of\ninternal torsion. We find that the highest packing densities are achieved in\nlow torsion packings for large systems, but in high torsion packings for small\nsystems. An analysis of both situations is given in terms of energetics and\ncomparison is made to analytical models of DNA packing in viral capsids."
    },
    {
        "anchor": "Multiple-Relaxation-Time Lattice Boltzmann Approach to Compressible\n  Flows with Flexible Specific-Heat Ratio and Prandtl Number: A new multiple-relaxation-time lattice Boltzmann scheme for compressible\nflows with arbitrary specific heat ratio and Prandtl number is presented. In\nthe new scheme, which is based on a two-dimensional 16-discrete-velocity model,\nthe moment space and the corresponding transformation matrix are constructed\naccording to the seven-moment relations associated with the local equilibrium\ndistribution function. In the continuum limit, the model recovers the\ncompressible Navier-Stokes equations with flexible specific-heat ratio and\nPrandtl number. Numerical experiments show that compressible flows with strong\nshocks can be simulated by the present model up to Mach numbers $Ma \\sim 5$.",
        "positive": "Crystal-liquid interfacial free energy of hard spheres via a novel\n  thermodynamic integration scheme: The hard sphere crystal-liquid interfacial free energy, ($\\gamma_{\\rm cl}$),\nis determined from molecular dynamics simulations using a novel thermodynamic\nintegration (TI) scheme. The advantage of this TI scheme compared to previous\nmethods is to successfully circumvent hysteresis effects due to the movement of\nthe crystal-liquid interface. This is accomplished by the use of extremely\nshort-ranged and impenetrable Gaussian flat walls which prevent the drift of\nthe interface while imposing a negligible free-energy penalty. We find that it\nis crucial to analyze finite-size effects in order to obtain reliable estimates\nof $\\gamma_{\\rm cl}$ in the thermodynamic limit."
    },
    {
        "anchor": "Membrane structure formation induced by two types of banana-shaped\n  proteins: The assembly of banana-shaped rodlike proteins on membranes, and the\nassociated membrane shape transformations, are investigated by analytical\ntheory and coarse-grained simulations. The membrane-mediated interactions\nbetween two banana-shaped inclusions are derived theoretically using a\npoint-like formalism based on fixed anisotropic curvatures, both for zero\nsurface tension and for finite surface tension. On a larger scale, the\ninteractions between assemblies of such rodlike inclusions are determined\nanalytically. Meshless membrane simulations are performed in the presence of a\nlarge number of inclusions of two types, corresponding to curved rods of\nopposite curvatures, both for flat membranes and vesicles. Rods of the same\ntype aggregate into linear assemblies perpendicular to the rod axis, leading to\nmembrane tubulation. However, rods of the other type, those of opposite\ncurvature, are attracted to the lateral sides of these assemblies, and\nstabilize a straight bump structure that prevents tubulation. When the two\ntypes of rods have almost opposite curvatures, the bumps attract one another,\nforming a stripe structure. Positive surface tension is found to stabilize the\nstripe formation. The simulation results agree well with the theoretical\npredictions provided the point-like curvatures of the model are scaled-down to\naccount for the effective flexibility of the simulated rods.",
        "positive": "Delocalization Transition in Colloidal Crystals: Sublattice melting is the loss of order of one lattice component in binary or\nternary ionic crystals upon increase in temperature. A related transition has\nbeen predicted in colloidal crystals. To understand the nature of this\ntransition, we study delocalization in self-assembled, size asymmetric binary\ncolloidal crystals using a generalized molecular dynamics model. Focusing on\nBCC lattices, we observe a smooth change from localized-to-delocalized\ninterstitial particles for a variety of interaction strengths. Thermodynamic\narguments, mainly the absence of a discontinuity in the heat capacity, suggest\nthat the passage from localization-to-delocalization is continuous and not a\nphase transition. This change is enhanced by lattice vibrations, and the\ntemperature of the onset of delocalization can be tuned by the strength of the\ninteraction between the colloid species. Therefore, the localized and\ndelocalized regimes of the sublattice are dominated by enthalpic and entropic\ndriving forces, respectively. This work sets the stage for future studies of\nsublattice melting in colloidal systems with different stoichiometries and\nlattice types, and it provides insights into superionic materials, which have\npotential for application in energy storage technologies."
    },
    {
        "anchor": "Theory of monolayers with boundaries: Exact results and Perturbative\n  analysis: Domains and bubbles in tilted phases of Langmuir monolayers contain a class\nof textures knows as boojums. The boundaries of such domains and bubbles may\ndisplay either cusp-like features or indentations. We derive analytic\nexpressions for the textures within domains and surrounding bubbles, and for\nthe shapes of the boundaries of these regions. The derivation is perturbative\nin the deviation of the bounding curve from a circle. This method is not\nexpected to be accurate when the boundary suffers large distortions, but it\ndoes provide important clues with regard to the influence of various energetic\nterms on the order-parameter texture and the shape of the domain or bubble\nbounding curve. We also look into the effects of thermal fluctuations, which\ninclude a sample-size-dependent effective line tension.",
        "positive": "Extended dynamical density functional theory for colloidal mixtures with\n  temperature gradients: In the past decade, classical dynamical density functional theory (DDFT) has\nbeen developed and widely applied to the Brownian dynamics of interacting\ncolloidal particles. One of the possible derivation routes of DDFT from the\nmicroscopic dynamics is via the Mori-Zwanzig-Forster projection operator\ntechnique with slowly varying variables such as the one-particle density. Here,\nwe use the projection operator approach to extend DDFT into various directions:\nfirst, we generalize DDFT toward mixtures of $n$ different species of spherical\ncolloidal particles. We show that there are in general nontrivial\ncross-coupling terms between the concentration fields and specify them\nexplicitly for colloidal mixtures with pairwise hydrodynamic interactions.\nSecondly, we treat the energy density as an additional slow variable and derive\nformal expressions for an extended DDFT containing also the energy density. The\nlatter approach can in principle be applied to colloidal dynamics in a nonzero\ntemperature gradient. For the case without hydrodynamic interactions the\ndiffusion tensor is diagonal, while thermodiffusion -- the dissipative\ncross-coupling term between energy density and concentration -- is nonzero in\nthis limit. With finite hydrodynamic interactions also cross-diffusion\ncoefficients assume a finite value. We demonstrate that our results for the\nextended DDFT contain the transport coefficients in the hydrodynamic limit\n(long wavelengths, low frequencies) as a special case."
    },
    {
        "anchor": "Screening model for nanowire surface-charge sensors in liquid: The conductance change of nanowire field-effect transistors is considered a\nhighly sensitive probe for surface charge. However, Debye screening of relevant\nphysiological liquid environments challenge device performance due to competing\nscreening from the ionic liquid and nanowire charge carriers. We discuss this\neffect within Thomas-Fermi and Debye-Huckel theory and derive analytical\nresults for cylindrical wires which can be used to estimate the sensitivity of\nnanowire surface-charge sensors. We study the interplay between the nanowire\nradius, the Thomas-Fermi and Debye screening lengths, and the length of the\nfunctionalization molecules. The analytical results are compared to\nfinite-element calculations on a realistic geometry.",
        "positive": "Translocation through environments with time dependent mobility: We consider single particle and polymer translocation where the frictional\nproperties experienced from the environment are changing in time. This work is\nmotivated by the interesting frequency responsive behaviour observed when a\npolymer is passing through a pore with an oscillating width. In order to\nexplain this better we construct general diffusive and non-diffusive frequency\nresponse of the gain in translocation time for a single particle in changing\nenvironments and look at some specific variations. For two state confinement,\nwhere the particle either has constant drift velocity or is stationary, we find\nexact expressions for both the diffusive and non-diffusive gain. We then apply\nthis approach to polymer translocation under constant forcing through a pore\nwith a sinusoidally varying width. We find good agreement for small polymers at\nlow frequency oscillation with deviations occurring at longer lengths and\nhigher frequencies. Unlike periodic forcing of a single particle at constant\nmobility, constant forcing with time dependent mobility is amenable to exact\nsolution through manipulation of the Fokker-Planck equation."
    },
    {
        "anchor": "Anisotropic particles in two-dimensional convective turbulence: The orientational dynamics of inertialess anisotropic particles transported\nby two-dimensional convective turbulent flows display a coexistence of regular\nand chaotic features. We numerically demonstrate that very elongated particles\n(rods) align preferentially with the direction of the fluid flow, i.e.,\nhorizontally close to the isothermal walls and dominantly vertically in the\nbulk. This behaviour is due to the the presence of a persistent large scale\ncirculation flow structure, which induces strong shear at wall boundaries and\nin up/down-welling regions. The near-wall horizontal alignment of rods persists\nat increasing the Rayleigh number, while the vertical orientation in the bulk\nis progressively weakened by the corresponding increase of turbulence\nintensity. Furthermore, we show that very elongated particles are nearly\northogonal to the orientation of the temperature gradient, an alignment\nindependent of the system dimensionality and which becomes exact only in the\nlimit of infinite Prandtl number. Tumbling rates are extremely vigorous\nadjacent to the walls, where particles roughly perform Jeffery orbits. This\nimplies that the root-mean-square near-wall tumbling rates for spheres are much\nstronger than for rods, up to $\\mathcal{O}(10)$ times at $Ra\\simeq 10^9$. In\nthe turbulent bulk the situation reverses and rods tumble slightly faster than\nisotropic particles, in agreement with earlier observations in two-dimensional\nturbulence.",
        "positive": "The Localization Transition of the Two-Dimensional Lorentz Model: We investigate the dynamics of a single tracer particle performing Brownian\nmotion in a two-dimensional course of randomly distributed hard obstacles. At a\ncertain critical obstacle density, the motion of the tracer becomes anomalous\nover many decades in time, which is rationalized in terms of an underlying\npercolation transition of the void space. In the vicinity of this critical\ndensity the dynamics follows the anomalous one up to a crossover time scale\nwhere the motion becomes either diffusive or localized. We analyze the scaling\nbehavior of the time-dependent diffusion coefficient D(t) including corrections\nto scaling. Away from the critical density, D(t) exhibits universal\nhydrodynamic long-time tails both in the diffusive as well as in the localized\nphase."
    },
    {
        "anchor": "Statistical Mechanical Analysis of the Electromechanical Coupling in an\n  Electrically-Responsive Polymer Chain: Polymeric materials that couple deformation and electrostatics have the\npotential for use in soft sensors and actuators with potential applications\nranging from robotic, biomedical, energy, aerospace and automotive\ntechnologies. In contrast to the mechanics of polymers that has been studied\nusing statistical mechanics approaches for decades, the coupled response under\ndeformation and electrical field has largely been modeled only\nphenomenologically at the continuum scale. In this work, we examine the physics\nof the coupled deformation and electrical response of an\nelectrically-responsive polymer chain using statistical mechanics. We begin\nwith a simple anisotropic model for the electrostatic dipole response to\nelectric field of a single monomer, and use a separation of energy scales\nbetween the electrostatic field energy and the induced dipole field energy to\nreduce the nonlocal and infinite-dimensional statistical averaging to a simpler\nlocal finite-dimensional averaging. In this simplified setting, we derive the\nequations of the most likely monomer orientation density using the maximum term\napproximation, and a chain free energy is derived using this approximation.\nThese equations are investigated numerically and the results provide insight\ninto the physics of electro-mechanically coupled elastomer chains. Closed-form\napproximations are also developed in the limit of small electrical energy with\nrespect to thermal energy; in the limit of small mechanical tension force\nacting on the chain; and using asymptotic matching for general chain\nconditions.",
        "positive": "Particle Shape Effects on the Stress Response of Granular Packings: We present measurements of the stress response of packings formed from a wide\nrange of particle shapes. Besides spheres these include convex shapes such as\nthe Platonic solids, truncated tetrahedra, and triangular bipyramids, as well\nas more complex, non-convex geometries such as hexapods with various arm\nlengths, dolos, and tetrahedral frames. All particles were 3D-printed in hard\nresin. Well-defined initial packing states were established through\npreconditioning by cyclic loading under given confinement pressure. Starting\nfrom such initial states, stress-strain relationships for axial compression\nwere obtained at four different confining pressures for each particle type.\nWhile confining pressure has the largest overall effect on the mechanical\nresponse, we find that particle shape controls the details of the stress-strain\ncurves and can be used to tune packing stiffness and yielding. By correlating\nthe experimentally measured values for the effective Young's modulus under\ncompression, yield stress and energy loss during cyclic loading, we identify\ntrends among the various shapes that allow for designing a packing's aggregate\nbehavior."
    },
    {
        "anchor": "How to Measure Forces when the Atomic Force Microscope shows Non-Linear\n  Compliance: A spreadsheet algorithm is given for the atomic force microscope that\naccounts for non-linear behavior in the deflection of the cantilever and in the\nphoto-diode response. In addition, the data analysis algorithm takes into\naccount cantilever tilt, friction in contact, and base-line artifacts such as\ndrift, virtual deflection, and non-zero force. These are important for accurate\nforce measurement and also for calibration of the cantilever spring constant.\nThe zero of separation is determined automatically, avoiding human intervention\nor bias. The method is illustrated by analyzing measured data for the\nsilica-silica drainage force and slip length.",
        "positive": "Quantifying thermally induced flowability of rennet cheese curds: Conversion of liquid milk to cheese curds is the first stage in cheese\nmanufacture. Changing the rigidity of cheese curds through heating and pH\ncontrol is an established method for preparing fresh curds, whereas a similar\nmethod to prepare fully coagulated curds is largely unknown. This study\nelucidated the effect of temperature variation on the viscoelastic moduli of\nfully coagulated curds under different pH conditions. The results showed that\nrennet curds treated at pH 4.8 exhibited drastic changes in the viscoelasticity\nat 43 degrees C, above which the degree of fluidity exceeded the degree of\nrigidity. The viscoelastic moduli exhibited exponential decay as a function of\ntemperature, which was independent of pH."
    },
    {
        "anchor": "Stokes' second problem and reduction of inertia in active fluids: We study a generalized Navier-Stokes model describing the thin-film flows in\nnon-dilute suspensions of ATP-driven microtubules or swimming bacteria that are\nenclosed by a moving ring-shaped container. Considering Stokes' second problem,\nwhich concerns the motion of an oscillating boundary, our numerical analysis\npredicts that a periodically rotating ring will oscillate at a higher frequency\nin an active fluid than in a passive fluid, due to an activity-induced\nreduction of the fluid inertia. In the case of a freely suspended\nfluid-container system that is isolated from external forces or torques, active\nfluid stresses can induce large fluctuations in the container's angular\nmomentum if the confinement radius matches certain multiples of the intrinsic\nvortex size of the active suspension. This effect could be utilized to\ntransform collective microscopic swimmer activity into macroscopic motion in\noptimally tuned geometries.",
        "positive": "Study of the validity of a combined potential model using the hybrid\n  reverse Monte Carlo method in fluoride glass system: The choice of appropriate interaction models is among the major disadvantages\nof conventional methods such as molecular dynamics and Monte Carlo simulations.\nOn the other hand, the so-called reverse Monte Carlo (RMC) method, based on\nexperimental data, can be applied without any interatomic and/or intermolecular\ninteractions. The RMC results are accompanied by artificial satellite peaks. To\nremedy this problem, we use an extension of the RMC algorithm, which introduces\nan energy penalty term into the acceptance criteria. This method is referred to\nas the hybrid reverse Monte Carlo (HRMC) method. The idea of this paper is to\ntest the validity of a combined potential model of coulomb and Lennard-Jones in\na fluoride glass system BaMnMF_{7} (M=Fe,V) using HRMC method. The results show\na good agreement between experimental and calculated characteristics, as well\nas a meaningful improvement in partial pair distribution functions. We suggest\nthat this model should be used in calculating the structural properties and in\ndescribing the average correlations between components of fluoride glass or a\nsimilar system. We also suggest that HRMC could be useful as a tool for testing\nthe interaction potential models, as well as for conventional applications."
    },
    {
        "anchor": "Force-velocity correlations in a dense, collisional, granular flow: We report measurements in a 2-dimensional, gravity-driven, collisional,\ngranular flow of the normal force delivered to the wall and of particle\nvelocity at several points in the flow. The wall force and the flow velocity\nare negatively correlated. This correlation falls off only slowly with distance\ntransverse to the flow, but dies away on the scale of a few particle diameters\nupstream or downstream. The data support a picture of short-lived chains of\nfrequently colliding particles that extend transverse to the flow direction,\nmaking transient load-bearing bridges that cause bulk fluctuations in the flow\nvelocity. The time-dependence of these spatial correlation functions indicate\nthat while the force-bearing structures are local in space, their influence\nextends far upstream in the flow, albeit with a time-lag. This leads to\ncorrelated velocity fluctuations, whose spatial range increases as the jamming\nthreshold is approached.",
        "positive": "Inversion of Sequence of Diffusion and Density Anomalies in\n  Core-Softened Systems: In this paper we present a simulation study of water-like anomalies in\ncore-softened system introduced in our previous publications. We investigate\nthe anomalous regions for a system with the same functional form of the\npotential but with different parameters and show that the order of the region\nof anomalous diffusion and the region of density anomaly is inverted with\nincreasing the width of the repulsive shoulder."
    },
    {
        "anchor": "Effect of many-body interactions on the solid-liquid phase-behavior of\n  charge-stabilized colloidal suspensions: The solid-liquid phase-diagram of charge-stabilized colloidal suspensions is\ncalculated using a technique that combines a continuous Poisson-Boltzmann\ndescription for the microscopic electrolyte ions with a molecular-dynamics\nsimulation for the macroionic colloidal spheres. While correlations between the\nmicroions are neglected in this approach, many-body interactions between the\ncolloids are fully included. The solid-liquid transition is determined at a\nhigh colloid volume fraction where many-body interactions are expected to be\nstrong. With a view to the Derjaguin-Landau-Verwey-Overbeek theory predicting\nthat colloids interact via Yukawa pair-potentials, we compare our results with\nthe phase diagram of a simple Yukawa liquid. Good agreement is found at high\nsalt conditions, while at low ionic strength considerable deviations are\nobserved. By calculating effective colloid-colloid pair-interactions it is\ndemonstrated that these differences are due to many-body interactions. We\nsuggest a density-dependent pair-potential in the form of a truncated Yukawa\npotential, and show that it offers a considerably improved description of the\nsolid-liquid phase-behavior of concentrated colloidal suspensions.",
        "positive": "RheoSpeckle: a new tool to investigate local flow and microscopic\n  dynamics of soft matter under shear: To investigate the interplay between microscopic dynamics and macroscopic\nrheology in soft matter, we couple a stress-controlled-rheometer equipped with\na Couette cell to a light scattering setup in the imaging geometry, which\nallows us to measure both the deformation field and the microscopic dynamics.\nTo validate our setup, we test two model systems. For an elastic solid sample,\nwe recover the expected deformation field within 1 micron. For a pure viscous\nfluid seeded with tracer particles, we measure the velocity profile and the\ndynamics of the tracers, both during shear and at rest. The velocity profile is\nacquired over a gap of 5 mm with a temporal and spatial resolution of 1 s and\n100 microns, respectively. At rest, the tracer dynamics have the expected\ndiffusive behavior. Under shear, the microscopic dynamics corrected for the\naverage drift due to solid rotation scale with the local shear rate,\ndemonstrating that our setup captures correctly the relative motion of the\ntracers due to the affine deformation."
    },
    {
        "anchor": "Mode-coupling theory for the dynamic heterogeneity in an aging glass:\n  How Do Glassy Domains Grow?: We construct the equations for the growth kinetics of an aging structural\nglass within mode-coupling theory through a non-stationary variant of the\n3-density correlator defined in Phys. Rev. Lett. {\\bf 97}, 195701 (2006). We\nsolve a schematic form of the resulting equations to obtain the coarsening of\nthe dynamic heterogeneity, characterized via the 3-point correlator\n$\\chi_3(t,t_w)$, as a function of waiting time $t_w$. For a quench into the\nglass, we find that $\\chi_3$ attains a peak value $\\sim t_w^{0.5}$ at $t -t_w\n\\sim t_w^{0.8}$, providing a theoretical basis for the numerical observations\nof Parisi [J. Phys. Chem. B \\textbf{103}, 4128 (1999)] and Kob and Barrat\n[Phys. Rev. Lett. \\textbf{78}, 4581 (1997)]. The aging is not \"simple\": the\n$t_w$ dependence cannot be attributed to an evolving effective temperature.",
        "positive": "Archimedean-like colloidal tilings on substrates with decagonal and\n  tetradecagonal symmetry: Two-dimensional colloidal suspensions subject to laser interference patterns\nwith decagonal symmetry can form an Archimedean-like tiling phase where rows of\nsquares and triangles order aperiodically along one direction [J. Mikhael et\nal., Nature 454, 501 (2008)]. In experiments as well as in Monte-Carlo and\nBrownian dynamics simulations, we identify a similar phase when the laser field\npossesses tetradecagonal symmetry. We characterize the structure of both\nArchimedean-like tilings in detail and point out how the tilings differ from\neach other. Furthermore, we also estimate specific particle densities where the\nArchimedean-like tiling phases occur. Finally, using Brownian dynamics\nsimulations we demonstrate how phasonic distortions of the decagonal laser\nfield influence the Archimedean-like tiling. In particular, the domain size of\nthe tiling can be enlarged by phasonic drifts and constant gradients in the\nphasonic displacement. We demonstrate that the latter occurs when the\ninterfering laser beams are not adjusted properly."
    },
    {
        "anchor": "Reversibility, Water-Mediated Switching, and Directed Cell Dynamics: Reversible switching of the complex network dynamics of proteins is mimicked\nin selected network glasses and compacted small carbohydrate molecules. Protein\ntransitions occur on long time scales ~ us -ms, evocative of the exponentially\nlarge viscosities found in glass-forming supercooled liquids just above the\nglass transition; in searching for mechanisms for reversibly slowed \"geared\nactivation\", Kauzmann was led from proteins to glasses. I show here that\nselected network glasses and small carbohydrate molecules can be used to model\nsuch transitions, and elucidate in particular some universal aspects of tandem\nrepeats. The human ankyrin tandem repeat D34, with a superhelical \"coiled\nspring\" structure which has 426 residues, folds reversibly and plastically.\nSuch molecules are too large for present transition-state numerical\nsimulations, currently limited to ~ 100 residues solvated by ~ 3000 water\nmolecules for times ~ ns. The transition states of D34 exhibit a surprisingly\nsimple collective (\"geared\") pattern when studied by fluorescence near its\ncenter, in samples modified mutageneously along its 12 helical repeats. One can\nunderstand this \"plastic\" pattern by taking advantage of a symmetric 45-atom\ncarbohydrate molecular bridge to \"cross over\" from proteins to inorganic\nnetwork glasses. There one easily identifies gears, and can show that the\ncollective pattern is the signature of nonlocal, water-mediated\n[hydro(phobic/philic)] switching. Details of the transition patterns emerge\nfrom analyzing the amino acid alpha helical repeat sequences with water-only\nhydrophobicity scales. Freezing and melting of monolayer water films at\nphysiological temperatures can enable ankyrin repeats to direct cell dynamics\nin muscles, membranes and cytoskeletons.",
        "positive": "Optically and elastically assembled plasmonic nanoantennae for spatially\n  resolved characterization of chemical composition in soft matter systems\n  using surface enhanced spontaneous and stimulated Raman scattering: We present a method to locally probe spatially varying chemical composition\nof soft matter systems by use of optically controlled and elastically\nself-assembled plasmonic nanoantennae. Disc-shaped metal particles with sharp\nirregular edges are optically trapped, manipulated, and assembled into small\nclusters to provide a strong enhancement of the Raman scattering signal coming\nfrom the sample regions around and in-between these particles. As the particles\nare reassembled and spatially translated by computer-controlled laser tweezers,\nwe probe chemical composition as a function of spatial coordinates. This allows\nus to reliably detect tiny quantities of organic molecules, such as capping\nligands present on various nanoparticles, as well as to probe chemical\ncomposition of the interior of liquid crystal defect cores that can be filled\nwith, for example, polymer chains. The strong electromagnetic field enhancement\nof optically-manipulated nanoparticles rough surfaces is demonstrated in\ndifferent forms of spectroscopy and microscopy, including enhanced spontaneous\nRaman scattering, coherent anti-Stokes Raman scattering, and stimulated Raman\nscattering imaging modes."
    },
    {
        "anchor": "Motility and self propulsion of active droplets: In the last years self-motile droplets attracted the attention of scientists\nfrom different fields ranging from applied biology to theoretical physics,\nbecause of their promising technological applications and important biological\nimplications. In this Chapter we review the state of the art of the research on\nactive droplets with a particular focus on theoretical and numerical studies.\nIn particular, we reviewed the active gel theory, namely a generalization of\nthe standard Landau-de Gennes theory for liquid crystals adapted to take into\naccount internal active injection due to the presence of self-motile\nconstituents. When confined in finite geometries, liquid crystalline-like\nsystems are also subject to topological constraints. Because of the relevance\nof topology in many different realizations of active droplets, we also reviewed\nsome fundamental topological concepts. We review how motility arises in\ndifferent realizations of active droplet both in 2d and 3d as the result of the\nbreaking of specific symmetries, by looking in particular detail at the case of\npolar and nematic droplets and shells of active liquid crystals.",
        "positive": "Malleable patterns from the evaporation of colloidal liquid bridge:\n  coffee ring to the scallop shell: The present article highlights an approach to generate contrasting patterns\nfrom drying droplets in a liquid bridge configuration, different from\nwell-known coffee rings. Reduction of the confinement distance (the gap between\nthe solid surfaces) leads to systematized nano-particle agglomeration yielding\nto spokes-like patterns similar to those found on scallop shells instead of\ncircumferential edge deposition. Alteration of the confinement length modulates\nthe curvature that entails variations in the evaporation flux across the\nliquid-vapor interface. Consequently, flow inside different liquid bridges\n(LBs) varies significantly for different confinement lengths. Small confinement\nlengths result in the stick-slip motion of squeezed liquid bridges. On the\ncontrary, the stretched LBs exhibit pinned contact lines. We decipher a\nproposition that a drying liquid thin film present during dewetting near the\nthree-phase contact line is responsible for the aligned deposition of\nparticles. The confinement distance determines the height of this thin film,\nand its theoretical estimations are validated against the experimental\nobservations using reflection interferometry, further exhibiting good agreement\n(in order of magnitude). Modulating the particle size does not significantly\ninfluence the precipitate patterns; however, particle concentration can\nsubstantially affect the deposition patterns. The differences in deposition\npatterns are attributed to the complex interplay of the gradient of evaporation\nflux induced motion of contact line in combination with the drying of thin\nliquid film during dewetting."
    },
    {
        "anchor": "Indentation of a floating elastic sheet: Geometry versus applied tension: The localized loading of an elastic sheet floating on a liquid bath occurs at\nscales from a frog sitting on a lily pad to a volcano supported by the Earth's\ntectonic plates. The load is supported by a combination of the stresses within\nthe sheet (which may include applied tensions from, for example, surface\ntension) and the hydrostatic pressure in the liquid. At the same time, the\nsheet deforms, and may wrinkle, because of the load. We study this problem in\nterms of the (relatively weak) applied tension and the indentation depth. For\nsmall indentation depths, we find that the force--indentation curve is linear\nwith a stiffness that we characterize in terms of the applied tension and\nbending stiffness of the sheet. At larger indentations the force--indentation\ncurve becomes nonlinear and the sheet is subject to a wrinkling instability. We\nstudy this wrinkling instability close to the buckling threshold and calculate\nboth the number of wrinkles at onset and the indentation depth at onset,\ncomparing our theoretical results with experiments. Finally, we contrast our\nresults with those previously reported for very thin, highly bendable\nmembranes.",
        "positive": "Slip length dependent propulsion speed of catalytic colloidal swimmers\n  near walls: Catalytic colloidal swimmers that propel due to self-generated fluid flows\nexhibit strong affinity for surfaces. We here report experimental measurements\nof significantly different velocities of such microswimmers in the vicinity of\nsubstrates made from different materials. We find that velocities scale with\nthe solution contact angle $\\theta$ on the substrate, which in turn relates to\nthe associated hydrodynamic substrate slip length, as\n$V\\propto(\\cos\\theta+1)^{-3/2}$. We show that such dependence can be attributed\nto osmotic coupling between swimmers and substrate. Our work points out that\nhydrodynamic slip at the wall, though often unconsidered, can significantly\nimpact the self-propulsion of catalytic swimmers."
    },
    {
        "anchor": "Towards a statistical mechanical theory of active fluids: We present a stochastic description of a model of N mutually repelling active\nspheres in the presence of external fields and characterize its steady state\nbehavior. To reproduce the effects of the experimentally observed persistence\nof the trajectories of the active particles we consider a Gaussian forcing\nhaving a non vanishing correlation time $\\tau$, whose finiteness is a measure\nof the activity of the system. With these ingredients we show that it is\npossible to develop a statistical mechanical approach similar to the one\nemployed in the study of equilibrium liquids and to obtain the explicit form of\nthe many-particle distribution function by means of the multidimensional\nunified colored noise approximation. Such a distribution plays a role analogous\nto the Gibbs distribution in equilibrium statistical mechanics and provides a\ncomplete information about the microscopic state of the system. From here we\ndevelop a method to determine the one and two-particle distribution functions\nin the spirit of the Born-Green-Yvon (BGY) equations of equilibrium statistical\nmechanics. The resulting equations which contain extra-correlations induced by\nthe activity allow to determine the stationary density profiles in the presence\nof external fields, the pair correlations and the pressure of active fluids. In\nthe low density regime we obtain the effective pair potential $\\phi(r)$ acting\nbetween two isolated particles separated by a distance, $r$, showing the\nexistence an effective attraction between them induced by activity. Based on\nthese results, in the second half of the paper we propose a mean field theory\nas an approach simpler than the BGY hierarchy and use it to derive a van der\nWaals expression of the equation of state, which can serve as the basis to\nunderstand the phase behavior of active fluids.",
        "positive": "Communication: Inferring the equation of state of a metastable\n  hard-sphere fluid from the equation of state of a hard-sphere mixture at high\n  densities: A possible approximate route to obtain the equation of state of the\nmonodisperse hard-sphere system in the metastable fluid region from the\nknowledge of the equation of state of a hard-sphere mixture at high densities\nis discussed. The proposal is illustrated by using recent Monte Carlo\nsimulation data for the pressure of a binary mixture. It is further shown to\nexhibit high internal consistency."
    },
    {
        "anchor": "Roughening Transition in a Moving Contact Line: The dynamics of the deformations of a moving contact line on a disordered\nsubstrate is formulated, taking into account both local and hydrodynamic\ndissipation mechanisms. It is shown that both the coating transition in contact\nlines receding at relatively high velocities, and the pinning transition for\nslowly moving contact lines, can be understood in a unified framework as\nroughening transitions in the contact line. We propose a phase diagram for the\nsystem in which the phase boundaries corresponding to the coating transition\nand the pinning transition meet at a junction point, and suggest that for\nsufficiently strong disorder a receding contact line will leave a\nLandau--Levich film immediately after depinning. This effect may be relevant to\na recent experimental observation in a liquid Helium contact line on a Cesium\nsubstrate [C. Guthmann, R. Gombrowicz, V. Repain, and E. Rolley, Phys. Rev.\nLett. {\\bf 80}, 2865 (1998)].",
        "positive": "Effects of Friction and Disorder on the Quasi-Static Response of\n  Granular Solids to a Localized Force: The response to a localized force provides a sensitive test for different\nmodels of stress transmission in granular solids. The elasto-plastic models\ntraditionally used by engineers have been challenged by theoretical and\nexperimental results which suggest a wave-like (hyperbolic) propagation of the\nstress, as opposed to the elliptic equations of static elasticity. Numerical\nsimulations of two-dimensional granular systems subject to a localized external\nforce are employed to examine the nature of stress transmission in these\nsystems as a function of the magnitude of the applied force, the frictional\nparameters and the disorder (polydispersity). The results indicate that in\nlarge systems (typically considered by engineers), the response is close to\nthat predicted by isotropic elasticity whereas the response of small systems\n(or when sufficiently large forces are applied) is strongly anisotropic. In the\nlatter case the applied force induces changes in the contact network\naccompanied by frictional sliding. The larger the coefficient of static\nfriction, the more extended is the range of forces for which the response is\nelastic and the smaller the anisotropy. Increasing the degree of polydispersity\n(for the range studied, up to 25%) decreases the range of elastic response.\nThis article is an extension of a previously published letter [1]."
    },
    {
        "anchor": "Phase behavior of active Brownian disks, spheres, and dumbbells: In this paper we provide high precision estimates of the phase diagram of\nactive Brownian particles. We extract coexisting densities from simulations of\nphase separated states in an elongated box (slab geometry) which minimizes\nfinite-size effects and allows for precise determination of points on the\nbinodal lines. Using this method, we study the influence of both shape and\ndimensionality on the two-phase region. Active spheres and dumbbells of active\nparticles are compared to the known phase diagram of active Brownian disks. In\nthe case of dimers, both correlated and uncorrelated propulsion of the two\nbeads are studied. The influence of correlation is discussed through a simple\nmapping.",
        "positive": "Aggregate morphology of active Brownian particles on porous, circular\n  walls: We study the motility-induced aggregation of active Brownian particles (ABPs)\non a porous, circular wall. We observe that the morphology of aggregated\ndense-phase on a static wall depends on the wall porosity, particle motility,\nand the radius of the circular wall. Our analysis reveals two morphologically\ndistinct, dense aggregates; a connected dense cluster that spreads uniformly on\nthe circular wall and a localized cluster that breaks the rotational symmetry\nof the system. These distinct morphological states are similar to the\nmacroscopic structures observed in aggregates on planar, porous walls. We\nsystematically analyze the parameter regimes where the different morphological\nstates are observed. We further extend our analysis to motile circular rings.\nWe show that the motile ring propels almost ballistically due to the force\napplied by the active particles when they form a localized cluster, whereas it\nmoves diffusively when the active particles form a continuous cluster. This\nproperty demonstrates the possibility of extracting useful work from a system\nof ABPs, even without artificially breaking the rotational symmetry."
    },
    {
        "anchor": "Interplay of anisotropy in shape and interactions in charged platelet\n  suspensions: Motivated by the intriguing phase behavior of charged colloidal platelets, we\ninvestigate the structure and dynamics of charged repulsive disks by means of\nMonte-Carlo simulations. The electrostatic interactions are taken into account\nthrough an effective two-body potential, obtained within the non-linear\nPoisson-Boltzmann formalism, which has the form of anisotropic screened Coulomb\npotential. Recently, we showed that the original intrinsic anisotropy of the\nelectrostatic potential in competition with excluded volume effects leads to a\nrich phase behavior that not only includes various liquid-crsytalline phases\nbut also predicts the existence of novel structures composed of alternating\nnematic-antinematic sheets. Here, we examine the structural and dynamical\nsignatures of each of the observed structures for both translational and\nrotational degrees of freedom. Finally, we discuss the influence of effective\ncharge value and our results in relation to experimental findings on charged\nplatelet suspensions.",
        "positive": "Wrapping liquids, solids, and gases in thin sheets: Many objects in nature and industry are wrapped in a thin sheet to enhance\ntheir chemical, mechanical, or optical properties. There are similarly a\nvariety of methods for wrapping, from pressing a film onto a hard substrate, to\nusing capillary forces to spontaneously wrap droplets, to inflating a closed\nmembrane. Each of these settings raises challenging nonlinear problems\ninvolving the geometry and mechanics of a thin sheet, often in the context of\nresolving a geometric incompatibility between two surfaces. Here we review\nrecent progress in this area, focusing on highly bendable films that are\nnonetheless hard to stretch, a class of materials that includes polymer films,\nmetal foils, textiles, graphene, as well as some biological materials.\nSignificant attention is paid to two recent advances: (i) a novel isometry that\narises in the doubly-asymptotic limit of high flexibility and weak tensile\nforcing, and (ii) a simple geometric model for predicting the overall shape of\nan interfacial film while ignoring small-scale wrinkles, crumples, and folds."
    },
    {
        "anchor": "On the role of Boundary Condition on the Speed- & Impact- Distributions\n  in Dissipative Granular Gases in Knudsen Regime Excited by Vibration: Recent experimental results on granular gas in Knudsen regime excited by a\nvibrating piston in micro-gravity have measured distribution p(I) of impacts I\nwith a fix target. They give p(I) scaling as exp(-I/Io). This distribution\nleads to a probability distribution function of speed v along z varying\napproximately as f(v) scaling as (1/v) exp(-v/vo); hence it diverges as 1/v at\nsmall speed and it is quite non Boltzmannian at large speed. Here, a model is\nproposed, which explains these experimental impact distributions; it takes\naccount of the true role of the boundaries and of the dissipation in the gas.\nThis validates the experimental data. Different approximations are discussed.\nRoles of boundaries and of 0-g condition are investigated theoretically. It is\nargued that the piston plays the role of an impact generator or a \"velostat\"\nfor the Knudsen gas. These results cast a doubt on the efficiency of the notion\nof Boltzmann temperature and on the necessity to refer to Boltzman distribution\nin such dilute systems. The model shows also that the medium has to be\nconsidered as a whole, in global equilibrium: each part of the system is\nexchanging with the whole (at least in the direction of vibration); this is\nquite different from classic approach of dissipative systems based on local\nexchange and equilibrium, which leads to a \"diffusive\" Boltzmann equation; here\nthe distribution f(z,t) is mainly propagative, i.e. f(z,v,t+dt)=f(z-vdt,v,t)\ninstead of diffusive.\n  Pacs # : 05.45.-a, 45.50.-j, 45.70.-n, 81.70.Bt, 81.70.Ha, 83.10.Pp",
        "positive": "Splitting Instability of a Multiply Charged Vortex in a Bose-Einstein\n  Condensate: We consider the splitting mechanism of a multiply charged vortex into singly\ncharged vortices in a Bose-Einstein condensate confined in a harmonic potential\nat zero temperature. The Bogoliubov equations support unstable modes with\ncomplex eigenfrequencies (CE modes), which cause the splitting instability\nwithout the influence of thermal atoms. The investigation of the excitation\nspectra shows that the negative-energy (NE) mode plays an important role in the\nappearance of the CE modes. The configuration of vortices in splitting is\ndetermined by the angular momentum of the associated NE mode. This structure\nhas also been confirmed by the numerical simulation of the time-dependent\nGross-Pitaevskii equation."
    },
    {
        "anchor": "Molecular dynamics simulations of the evaporation of particle-laden\n  droplets: We use molecular dynamics simulations to study the evaporation of\nparticle-laden droplets on a heated surface. The droplets are composed of a\nLennard-Jones fluid containing rigid particles which are spherical sections of\nan atomic lattice, and heating is controlled through the temperature of an\natomistic substrate. We observe that sufficiently large (but still nano-sized)\nparticle-laden drops exhibit contact line pinning, measure the outward fluid\nflow field which advects particle to the drop rim, and find that the structure\nof the resulting aggregate varies with inter-particle interactions. In\naddition, the profile of the evaporative fluid flux is measured with and\nwithout particles present, and is also found to be in qualitative agreement\nwith earlier theory. The compatibility of simple nanoscale calculations and\nmicron-scale experiments indicates that molecular simulation may be used to\npredict aggregate structure in evaporative growth processes.",
        "positive": "Elastogranular Mechanics: Buckling, Jamming, and Structure Formation: Confinement of a slender body into a granular array induces stress\nlocalization in the geometrically nonlinear structure, and jamming, reordering,\nand vertical dislocation of the surrounding granular medium. By varying the\ninitial packing density of grains and the length of a confined elastica, we\nidentify the critical length necessary to induce jamming, and demonstrate an\nintricate coupling between folds that localize along grain boundaries. Above\nthe jamming threshold, the characteristic length of elastica deformation is\nshown to scale with the length over which force field fluctuations propagate in\na jammed state, suggesting the ordering of the granular array governs the\ndeformation of the slender structure. However, over confinement of the elastica\nwill induce a form of stress relaxation in the granular medium by dislocating\ngrains through two distinct mechanisms that depend on the geometry of the\nconfined structure."
    },
    {
        "anchor": "Deformation induced changes in surface properties of polymers\n  investigated by scanning force microscopy: In this study the possibility of combining commercial Scanning Force\nMicroscopes (SFM) with stretching devices for the investigation of microscopic\nsurface changes during stepwise elongation is investigated. Different types of\nstretching devices have been developed either for Scanning Platform-SFM or for\nStand Alone-SFM. Their suitability for the investigation of deformation induced\nsurface changes is demonstrated. A uniaxially oriented polypropylene film is\nstretched vertically to its extrusion direction. The reorientation of its\nmicrofibrillar structure is investigated and correlated to macroscopic\nstructural changes determined by taking a force-elongation curve. Microtome\ncuts of natural rubber filled with 15 PHR carbon black are stretched. Changes\nin topography, local stiffness and adhesive force are simultaneously reported\nby using a new imaging method called Pulsed Force Mode (PFM).",
        "positive": "Propulsion of a molecular machine by asymmetric distribution of\n  reaction--products: A simple model for the reaction-driven propulsion of a small device is\nproposed as a model for (part of) a molecular machine in aqueous media. Motion\nof the device is driven by an asymmetric distribution of reaction products. The\npropulsive velocity of the device is calculated as well as the scale of the\nvelocity fluctuations. The effects of hydrodynamic flow as well as a number of\ndifferent scenarios for the kinetics of the reaction are addressed."
    },
    {
        "anchor": "Influence of anisotropic ion shape, asymmetric valency, and electrolyte\n  concentration on structural and thermodynamic properties of an electric\n  double layer: Grand canonical Monte Carlo simulation results are reported for an electric\ndouble layer modelled by a planar charged hard wall, anisotropic shape cations,\nand spherical anions at different electrolyte concentrations and asymmetric\nvalencies. The cations consist of two tangentially tethered hard spheres of the\nsame diameter, $d$. One sphere is charged while the other is neutral. Spherical\nanions are charged hard spheres of diameter $d$. The ion valency asymmetry 1:2\nand 2:1 is considered, with the ions being immersed in a solvent mimicked by a\ncontinuum dielectric medium at standard temperature. The simulations are\ncarried out for the following electrolyte concentrations: 0.1, 1.0 and 2.0 M.\nProfiles of the electrode-ion, electrode-neutral sphere singlet distributions,\nthe average orientation of dimers, and the mean electrostatic potential are\ncalculated for a given electrode surface charge, $\\sigma$, while the contact\nelectrode potential and the differential capacitance are presented for varying\nelectrode charge. With an increasing electrolyte concentration, the shape of\ndifferential capacitance curve changes from that with a minimum surrounded by\nmaxima into that of a distorted single maximum. For a 2:1 electrolyte, the\nmaximum is located at a small negative $\\sigma$ value while for 1:2, at a small\npositive value.",
        "positive": "Computation of Unconstrained Elastic Equilibria of Complete M\u00f6bius\n  Bands and their Stability: Determining the equilibrium configuration of an elastic M\\\"{o}bius band is a\nchallenging problem. In recent years numerical results have been obtained by\nother investigators, employing first the Kirchhoff theory of rods and later the\ndevelopable, ruled-surface model of Wunderlich. In particular, the strategy\nemployed previously for the latter does not deliver an unconstrained\nequilibrium configuration for the complete strip. Here we present our own\nsystematic approach to the same problem for each of these models, with the\nultimate goal of assessing the stability of flip-symmetric configurations. The\npresence of pointwise constraints considerably complicates the latter step. We\nobtain the first stability results for the problem, numerically demonstrating\nthat such equilibria render the total potential energy a local minimum. Along\nthe way we introduce a novel regularization for the for the singular Wunderlich\nmodel that delivers unconstrained equilibria for the complete strip, which can\nthen be tested for stability."
    },
    {
        "anchor": "Droplets sit and slide anisotropically on soft, stretched substrates: Anisotropically wetting substrates enable useful control of droplet behavior\nacross a range of applications. Usually, these involve chemically or physically\npatterning the substrate surface, or applying gradients in properties like\ntemperature or electrical field. Here, we show that a flat, stretched, uniform\nsoft substrate also exhibits asymmetric wetting, both in terms of how droplets\nslide and in their static shape. Droplet dynamics are strongly affected by\nstretch: glycerol droplets on silicone substrates with a 23\\% stretch slide\n67\\% faster in the direction parallel to the applied stretch than in the\nperpendicular direction. Contrary to classical wetting theory, static droplets\nin equilibrium appear elongated, oriented parallel to the stretch direction.\nBoth effects arise from droplet-induced deformations of the substrate near the\ncontact line.",
        "positive": "Axial Sand-Water Segregation: A novel pattern forming instability in a mixture of a granular material and\nwater in a horizontal rotating drum is experimentally investigated. The\nparticles accumulate in radial symmetric rings separated by pure water. The\ntransition between the homogeneous state and the structured state is\nhysteretic. The transition point is extrapolated from the growth rates of the\nchain of rings. The trajectory of a single particle is discussed to estimate an\nupper boundary for the transition point."
    },
    {
        "anchor": "Anisotropic van der Waals Dispersion Forces in Polymers: Structural\n  Symmetry Breaking Leads to Enhanced Conformational Search: The modeling of conformations and dynamics of (bio)polymers is of primary\nimportance for understanding physicochemical properties of soft matter.\nAlthough short-range interactions such as covalent and hydrogen bonding control\nthe local arrangement of polymers, non-covalent interactions play a dominant\nrole in determining the global conformations. Here we focus on how the\ninclusion of many-body effects in van der Waals dispersion affects the outcome\nof geometry optimizations and molecular dynamics simulations of model polymers.\nWe find that delocalized force contributions are key to explore the\nconformational landscape, as they induce an anisotropic polarization response\nwhich efficiently guides the conformation towards globally optimized\nstructures. This is in contrast with the commonly used pair-wise approach,\nwhere the atomic polarizabilities lack information on the global geometry. We\nshow that such local approximation causes the conformational search to be\nobstructed by conformations with unphysically limited spatial symmetry, while\nthe many-body formalism strongly reduces the roughness of the potential energy\nlandscape.",
        "positive": "A Light-weight Vibrational Motor Powered Recoil Robot that Hops Rapidly\n  Across Granular Media: A 1 cm coin vibrational motor fixed to the center of a 4 cm square foam\nplatform moves rapidly across granular media (poppy seeds, millet, corn meal)\nat a speed of up to 30 cm/s, or about 5 body lengths/s. Fast speeds are\nachieved with dimensionless acceleration number, similar to a Froude number, up\nto 50, allowing the light-weight 1.4 g mechanism to remain above the substrate,\nlevitated and propelled by its kicks off the surface. The mechanism is low cost\nand moves without any external moving parts. With 2 s exposures we photograph\nthe trajectory of the mechanism using an LED blocked except for a pin-hole and\nfixed to the mechanism. Trajectories can exhibit period doubling phenomena\nsimilar to a ball bouncing on a vibrating table top. A two dimensional\nnumerical model gives similar trajectories, though a vertical drag force is\nrequired to keep the mechanism height low. We attribute the vertical drag force\nto aerodynamic suction from air flow below the mechanism base and through the\ngranular substrate. Our numerical model suggests that speed is maximized when\nthe mechanism is prevented from jumping high off the surface. In this way the\nmechanism resembles a galloping or jumping animal whose body remains nearly at\nthe same height above the ground during its gait."
    },
    {
        "anchor": "Josephson Junction Arrays with Bose-Einstein Condensates: We report on the direct observation of an oscillating atomic current in a\none-dimensional array of Josephson junctions realized with an atomic\nBose-Einstein condensate. The array is created by a laser standing-wave, with\nthe condensates trapped in the valleys of the periodic potential and weakly\ncoupled by the inter-well barriers. The coherence of multiple tunneling between\nadjacent wells is continuously probed by atomic interference. The square of the\nsmall-amplitude oscillation frequency is proportional to the microscopic\ntunneling rate of each condensate through the barriers, and provides a direct\nmeasurement of the Josephson critical current as a function of the intermediate\nbarrier heights. Our superfluid array may allow investigation of phenomena so\nfar inaccessible to superconducting Josephson junctions and lays a bridge\nbetween the condensate dynamics and the physics of discrete nonlinear media.",
        "positive": "Induced cooperative motions in a medium driven at the nanoscale:\n  Searching for an optimum excitation period: Recent results have shown the appearance of induced cooperative motions\ncalled dynamic heterogeneity during the isomerization of diluted azobenzene\nmolecules in a host glass-former. In this paper we raise the issue of the\ncoupling between these \"artificial\" heterogeneities and the isomerization\nperiod. How do these induced heterogeneities differ in the saturation regime\nand in the linear response regime ? Is there a maximum of the heterogeneous\nmotion versus isomerization rate and why ? Are the heterogeneity evolution with\nthe isomerization rate connected with the diffusion or relaxation time\nevolution ? We use out of equilibrium molecular dynamics simulations to answer\nthese questions. We find that the heterogeneity increases in the linear\nresponse regime for large isomerization periods and small perturbations. In\ncontrast the heterogeneity decreases in the saturation regime, i.e. when the\nisomerization half-period ($\\tau_{p}/2$) is smaller than the relaxation time of\nthe material ($\\tau_{\\alpha}$). This result makes possible a test of the effect\nof cooperative motions on the dynamics using the chromophores as Maxwell demons\nthat destroy or stimulate the cooperative motions. Because the heterogeneities\nincrease in the linear regime and then decrease in the saturation regime, we\nfind a maximum for $\\tau_{p}/2 \\approx \\tau_{\\alpha}$. The induced excitations\nconcentration follows a power law evolution versus the isomerization rate and\nthen saturates. As a consequence the $\\alpha$ relaxation time is related to the\nexcitation concentration with a power law, a result in qualitative agreement\nwith recent findings in constrained models. This result supports a common\norigin for the heterogeneities with constrained models and a similar relation\nto the excitation concentration."
    },
    {
        "anchor": "Simulations of Coulomb systems with slab geometry using an efficient 3d\n  Ewald summation method: We present a new approach to efficiently simulate electrolytes confined\nbetween infinite charged walls using a 3d Ewald summation method. The optimal\nperformance is achieved by separating the electrostatic potential produced by\nthe charged walls from the electrostatic potential of electrolyte. The electric\nfield produced by 3d periodic images of the plates is constant, with the field\nproduced by the transverse images of the charged plates canceling out. We show\nthat under suitable renormalization, the non-neutral electrolyte confined\nbetween charged plates can be simulated using 3d Ewald summation with a\ncorrection that accounts for the conditional convergence of the resulting\nlattice sum. The new algorithm is at least an order of magnitude more rapid\nthan the usual simulation methods for the slab geometry and can be further sped\nup by adopting Particle-Particle Particle-Mesh (P 3 M ) approach.",
        "positive": "Growth of a flexible fibre in a deformable ring: We study the equilibrium configurations related to the growth of an elastic\nfibre in a confining flexible ring. This system represents a paradigm for a\nvariety of biological, medical, and engineering problems. We consider a\nsimplified geometry in which initially the container is a circular ring of\nradius $R$. Quasi-static growth is then studied by solving the equilibrium\nequations as the fibre length $l$ increases, starting from $l = 2R$.\nConsidering both the fibre and the ring as inextensible and unshearable, we\nfind that beyond a critical length, which depends on the relative bending\nstiffness, the fibre buckles. Furthermore, as the fibre grows further it folds,\ndistorting the ring until it induces a break in mirror symmetry at $l>2 \\pi R$.\nWe get that the equilibrium shapes depend only on two dimensionless parameters:\nthe length ratio $\\mu = l/R$ and the bending stiffnesses ratio $\\kappa$. These\nfindings are also supported by finite element simulation. Finally we\nexperimentally validate the theoretical results showing a very good\nquantitative prediction of the observed buckling and folding regimes at\nvariable geometrical parameters."
    },
    {
        "anchor": "Long-time anomalous swimmer diffusion in smectic liquid crystals: The dynamics of self-locomotion of active particles in aligned or liquid\ncrystalline fluids strongly deviates from that in simple isotropic media. We\nexplore the long-time dynamics of a swimmer moving in a three-dimensional\nsmectic liquid crystal and find that the mean-square displacement (MSD)\ntransverse to the director exhibits a distinct logarithmic tail at long times.\nThe scaling is distinctly different from that in an isotropic or nematic fluid\nand hints at the subtle but important role of the director fluctuation spectrum\nin governing the long-time motility of active particles. Our findings are based\non a generic hydrodynamic theory and Brownian dynamics computer simulation of a\nthree-dimensional soft mesogen model.",
        "positive": "Kinetic surface roughening for the Mullins-Herring equation: Using the linearity property of the Mullins-Herring equation when the\nvelocity is zero with a Gaussian noise, we obtain an analytic form for the\nglobal mean-square surface width and height-height correlation function. This\ncan be used to read the critical exponents in any dimension. In particular for\nd=1 we show that although the surface is super rough the system exhibits\nFamily-Vicsek scaling behavior."
    },
    {
        "anchor": "Translational and rotational Brownian displacements of colloidal\n  particles of complex shapes: The exact analytical expressions for the time-dependent cross-correlations of\nthe translational and rotational Brownian displacements of a particle with\narbitrary shape were derived by us in [J. Chem. Phys. 142, 214902 (2015) and\n144, 076101 (2016)]. They are in this work applied to construct a method to\nanalyze Brownian motion of a particle of an arbitrary shape, and to extract\naccurately the self-diffusion matrix from the measurements of the\ncross-correlations, which in turn allows to gain some information on the\nparticle structure. As an example, we apply our new method to analyze the\nexperimental results of D. J. Kraft et al. for the micrometer-sized aggregates\nof the beads [Phys. Rev. E 88, 050301 (R) (2013)]. We explicitly demonstrate\nthat our procedure, based on the measurements of the time-dependent\ncross-correlations in the whole range of times, allows to determine the self\ndiffusion (or alternatively the friction matrix) with a much higher precision\nthan the method based only on their initial slopes. Therefore, the analytical\ntime-dependence of the cross-correlations serves as a useful tool to extract\ninformation about particle structure from trajectory measurements.",
        "positive": "Solitary-wave description of condensate micro-motion in a time-averaged\n  orbiting potential trap: We present a detailed theoretical analysis of micro-motion in a time-averaged\norbiting potential trap. Our treatment is based on the Gross-Pitaevskii\nequation, with the full time dependent behaviour of the trap systematically\napproximated to reduce the trapping potential to its dominant terms. We show\nthat within some well specified approximations, the dynamic trap has\nsolitary-wave solutions, and we identify a moving frame of reference which\nprovides the most natural description of the system. In that frame eigenstates\nof the time-averaged orbiting potential trap can be found, all of which must be\nsolitary-wave solutions with identical, circular centre of mass motion in the\nlab frame. The validity regime for our treatment is carefully defined, and is\nshown to be satisfied by existing experimental systems."
    },
    {
        "anchor": "Viscoelastic multiscaling in immersed networks: Rheological responses are the most relevant features to describe soft matter.\nSo far, such constitutive relations are still not well understood in terms of\nsmall scale properties, although this knowledge would help the design of\nsynthetic and bio-materials. Here, we investigate, computational and\nanalytically, how mesoscopic-scale interactions influence the macroscopic\nbehavior of viscoelastic materials. We design a coarse-grained approach where\nthe local elastic and viscous contributions can be controlled. Applying\nmolecular dynamics simulations, we mimic real indentation assays. When elastic\nforces are dominant, our model reproduces the hertzian behavior. However, when\nfriction increases, it restores the Standard Linear Solid model. We show how\nthe response parameters depend on the microscopic elastic and viscous\ncontributions. Moreover, our findings also suggest that the relaxation times,\nobtained in relaxation and oscillatory experiments, obey a universal behavior\nin viscoelastic materials.",
        "positive": "Structural signatures of mobility on intermediate time scales in a\n  supercooled fluid: We use computer simulations to explore the manner in which the particle\ndisplacements on intermediate time scales in supercooled fluids correlate to\ntheir dynamic structural environment. The fluid we study, a binary mixture of\nhard spheres, exhibits classic signatures of dynamic heterogeneity, including a\nbifurcated single-particle displacement distribution (i.e., subpopulations of\nimmobile and mobile particles). We find that immobile particles, during the\ncourse of their displacements, exhibit stronger average pair correlations to\ntheir neighbors than mobile particles, but not necessarily higher average\ncoordination numbers. We discuss how the correlation between structure and\nsingle-particle dynamics depends on observation time."
    },
    {
        "anchor": "Effect of shape anisotropy on the phase diagram of the Gay-Berne fluid: We have used the density functional theory to study the effect of molecular\nelongation on the isotropic-nematic, isotropic-smectic A and nematic-smectic A\nphase transitions of a fluid of molecules interacting via the Gay-Berne\nintermolecular potential. We have considered a range of length-to-width\nparameter $3.0\\leq x_0\\leq 4.0$ in steps of 0.2 at different densities and\ntemperatures. Pair correlation functions needed as input information in density\nfunctional theory are calculated using the Percus-Yevick integral equation\ntheory. Within the small range of elongation, the phase diagram shows\nsignificant changes. The fluid at low temperature is found to freeze directly\nfrom isotropic to smectic A phase for all the values of $x_0$ considered by us\non increasing the density while nematic phase stabilizes in between isotropic\nand smectic A phases only at high temperatures and densities. Both\nisotropic-nematic and nematic-smectic A transition density and pressure are\nfound to decrease as we increase $x_0$. The phase diagram obtained is compared\nwith computer simulation result of the same model potential and is found to be\nin good qualitative agreement.",
        "positive": "Strain-dependent solid surface stress and the stiffness of soft contacts: Surface stresses have recently emerged as a key player in the mechanics of\nhighly compliant solids. The classic theories of contact mechanics describe\nadhesion with a compliant substrate as a competition between surface energies\ndriving deformation to establish contact and bulk elasticity resisting this.\nHowever, it has recently been shown that surface stresses provide an additional\nrestoring force that can compete with and even dominate over elasticity in\nhighly compliant materials, especially when length scales are small compared to\nthe ratio of the surface stress to the elastic modulus, $\\Upsilon/E$. Here, we\ninvestigate experimentally the contribution of surface stresses to the force of\nadhesion. We find that the elastic and capillary contributions to the adhesive\nforce are of similar magnitude, and that both are required to account for\nmeasured adhesive forces between rigid silica spheres and compliant, silicone\ngels. Notably, the strain-dependence of the solid surface stress contributes\nsignificantly to the stiffness of soft solid contacts."
    },
    {
        "anchor": "Moving contact line dynamics: from diffuse to sharp interfaces: We reconcile two scaling laws that have been proposed in the literature for\nthe slip length associated with a moving contact line in diffuse interface\nmodels, by demonstrating each to apply in a different regime of the ratio of\nthe microscopic interfacial width $l$ and the macroscopic diffusive length\n$l_D= (M\\eta)^{1/2}$, where $\\eta$ is the fluid viscosity and $M$ the mobility\ngoverning intermolecular diffusion. For small $l_D/l$ we find a diffuse\ninterface regime in which the slip length scales as $\\xi \\sim(l_Dl)^{1/2}$. For\nlarger $l_D/l>1$ we find a sharp interface regime in which the slip length\ndepends only on the diffusive length, $\\xi \\sim l_D \\sim (M\\eta)^{1/2}$, and\ntherefore only on the macroscopic variables $\\eta$ and $M$, independent of the\nmicroscopic interfacial width $l$. We also give evidence that modifying the\nmicroscopic interfacial terms in the model's free energy functional appears to\naffect the value of the slip length only the diffuse interface regime,\nconsistent with the slip length depending only on macroscopic variables in the\nsharp interface regime. Finally, we demonstrate the dependence of the dynamic\ncontact angle on the capillary number to be in excellent agreement with the\ntheoretical prediction of \\cite{Cox1986}, provided we allow the slip length to\nbe rescaled by a dimensionless prefactor. This prefactor appears to converge to\nunity in the sharp interface limit, but is smaller in the diffuse interface\nlimit. The excellent agreement of results obtained using three independent\nnumerical methods, across several decades of the relevant dimensionless\nvariables, demonstrates our findings to be free of numerical artifacts.",
        "positive": "Ultraslow settling kinetics of frictional cohesive powders: Using discrete element method simulations, we show that the settling of\nfrictional cohesive grains under ramped-pressure compression exhibits strong\nhistory dependence and slow dynamics that are not present for grains that lack\neither cohesion or friction. Systems prepared by beginning with a dilute state\nand then ramping the pressure to a small positive value $P_{\\rm final}$ over a\ntime $\\tau_{\\rm ramp}$ settle at packing fractions given by an\ninverse-logarithmic rate law, $\\phi_{\\rm settled}(\\tau_{\\rm ramp}) = \\phi_{\\rm\nsettled}(\\infty) + A/[1 + B\\ln(1 + \\tau_{\\rm ramp}/\\tau_{\\rm slow})]$. This law\nis analogous to the one obtained from classical tapping experiments on\nnoncohesive grains, but crucially different in that $\\tau_{\\rm slow}$ is set by\nthe slow dynamics of structural void stabilization rather than the faster\ndynamics of bulk densification. We formulate a kinetic free-void-volume theory\nthat predicts this $\\phi_{\\rm settled}(\\tau_{\\rm ramp})$, with $\\phi_{\\rm\nsettled}(\\infty) = \\phi_{\\rm ALP}$ and $A = \\phi_{\\rm settled}(0) - \\phi_{\\rm\nALP}$, where $\\phi_{\\rm ALP} \\equiv .135$ is the ``adhesive loose packing''\nfraction found by Liu \\textit{et al.} [W.\\ Liu, Y.\\ Jin, S. Chen, H.\\ A.\\ Makse\nand S.\\ Li, \\textit{Soft Matt.} \\textbf{13}, 421 (2017)]."
    },
    {
        "anchor": "Theoretical framework for pairwise microswimmer interactions: Hydrodynamic interactions are crucial for determining the cooperative\nbehavior of microswimmers at low Reynolds numbers. Here we provide a\ncomprehensive analysis of the scaling and strength of the interactions in the\ncase of a pair of three-sphere swimmers with intrinsic elasticity. Both\nstroke-based and force-based microswimmers are analyzed using an analytic\nperturbative approach. Following a detailed analysis of the passive\ninteractions, as well as active translations and rotations, we find that the\nmapping between the stroke-based and force-based swimmers is only possible in a\nlow driving frequency regime where the characteristic time scale is smaller\nthan the viscous one. Furthermore, we find that for swimmers separated by up to\nhundreds of swimmer lengths, swimming in pairs speeds up the self propulsion,\ndue to the dominant quadrupolar hydrodynamic interactions. Finally, we find\nthat the long term behavior of the swimmers, while sensitive to initial\nrelative positioning, does not depend on the pusher or puller nature of the\nswimmer.",
        "positive": "Dielectric response of a polar fluid trapped in a spherical nanocavity: We present extensive Molecular Dynamics simulation results for the structure,\nstatic and dynamical response of a droplet of 1000 soft spheres carrying\nextended dipoles and confined to spherical cavities of radii $R=2.5$, 3, and 4\nnm embedded in a dielectric continuum of permittivity $\\epsilon' \\geq 1$. The\npolarisation of the external medium by the charge distribution inside the\ncavity is accounted for by appropriate image charges. We focus on the influence\nof the external permittivity $\\epsilon'$ on the static and dynamic properties\nof the confined fluid. The density profile and local orientational order\nparameter of the dipoles turn out to be remarkably insensitive to $\\epsilon'$.\nPermittivity profiles $\\epsilon(r)$ inside the spherical cavity are calculated\nfrom a generalised Kirkwood formula. These profiles oscillate in phase with the\ndensity profiles and go to a ``bulk'' value $\\epsilon_b$ away from the\nconfining surface; $\\epsilon_b$ is only weakly dependent on $\\epsilon'$, except\nfor $\\epsilon' = 1$ (vacuum), and is strongly reduced compared to the\npermittivity of a uniform (bulk) fluid under comparable thermodynamic\nconditions.\n  The dynamic relaxation of the total dipole moment of the sample is found to\nbe strongly dependent on $\\epsilon'$, and to exhibit oscillatory behaviour when\n$\\epsilon'=1$; the relaxation is an order of magnitude faster than in the bulk.\nThe complex frequency-dependent permittivity $\\epsilon(\\omega)$ is sensitive to\n$\\epsilon'$ at low frequencies, and the zero frequency limit\n$\\epsilon(\\omega=0)$ is systematically lower than the ``bulk'' value\n$\\epsilon_b$ of the static primitivity."
    },
    {
        "anchor": "Depletion force in the infinite-dilution limit in a solvent of\n  nonadditive hard spheres: The mutual entropic depletion force felt by two solute \"big\" hard spheres\nimmersed in a binary mixture solvent of nonadditive \"small\" hard spheres is\ncalculated as a function of the surface-to-surface distance by means of\ncanonical Monte Carlo simulations and through a recently proposed\nrational-function approximation [Phys. Rev. E \\textbf{84}, 041201 (2011)]. Four\nrepresentative scenarios are investigated: symmetric solute particles and the\nlimit where one of the two solute spheres becomes a planar hard wall, in both\ncases with symmetric and asymmetric solvents. In all cases, the influence on\nthe depletion force due to the nonadditivity in the solvent is determined in\nthe mixed state. Comparison between results from the theoretical approximation\nand from the simulation shows a good agreement for surface-to-surface distances\ngreater than the smallest solvent diameter.",
        "positive": "How to make a cylinder roll uphill: Slithering, crawling, slipping, gliding are various modes of limbless\nlocomotion that have been mimicked for micro-manipulation of soft, slender and\nsessile objects. A lesser known mode is rolling which involves periodic,\nasymmetric and lateral muscular deformations. Here we enable an elastomeric\ncylinder of poly(dimethylsiloxane) to roll on a substrate by releasing small\nquantity of a solvent like chloroform, toluene, hexane, heptane and so on,\nwhich swells differentially a portion of the cylinder, but evaporates from\nportion of it which remains exposed to the atmosphere. In a dynamic situation,\nthis asymmetric swelling-shrinking cycle generates a torque which drives the\ncylinder to roll. The driving torque is strong enough that the cylinder can\nroll up an inclined plane, within a range of inclination, its velocity even\nincreases. The cylinder can even drag a dead weight significantly larger, ~8-10\ntimes its own weight. A scaling law is derived for optimizing the rolling\nvelocity."
    },
    {
        "anchor": "Rise or sink: spherical intruder in density frequency dependence static\n  granular fluid: A simple model for intruder in vibrating granular bed is constructed by\nintroducing a term that governs frequency dependent granular bed density.\nVarying the vibrating frequency will drive the buoyant force acting on the\nintruder by the granular bed. Swapped regions of rising and sinking intruder\ncompared to other reported result have bee found.",
        "positive": "Effect of solvent polarization on electric double layer of a charged\n  soft surface in an electrolyte solution: We study the electric double layer near a charged soft surface by using a\nmean-field approach including non-uniform size effect and solvent polarization.\nBased on a free energy model, electrostatic potential and number densities of\nwater and ions are obtained numerically by solving coupled differential\nequations including the Poisson's equation. We find that the solvent\npolarization significantly affects electrostatic potential, ion number\ndensities and permittivity in an electrolyte solution near a charged soft\nsurface. We prove that the consideration of the solvent polarization increases\nthe magnitude of Donnan potential. We also demonstrate that within the fixed\ncharge layer the number densities of counterions and coions are slightly\nsmaller than when the solvent polarization is not considered. An increase in\nthe ionic size enhances the influence of solvent polarization on the\nelectrostatic properties within the fixed charged layer of charged soft\nsurface. In the region of high surface-charge-density, the permittivity and the\nnumber density of water dipoles considerably decrease due to water\npolarization."
    },
    {
        "anchor": "Pattern formation and shocks in granular gases: Granular media such as sand and sugar are ubiquitous in nature and industry\nbut are less well understood than fluids or solids. We consider the behavior of\nrapid granular flows where the transfer of momenta by collisions dominates. The\nphysics is quite different for the opposite limit of static or slowly moving\ngrains (e.g., sand piles). To gain understanding of granular flows we consider\ntwo problems that have been investigated with experiments, particle simulations\nand hydrodynamic theory: vertically oscillating granular layers and flow past\nan obstacle. Oscillating granular layers spontaneously form spatial patterns\nwhen the container acceleration amplitude exceeds a critical value, about 2.5\ntimes the gravitational acceleration. Simulations with hard spheres that\nconserve linear momentum and dissipate energy in collisions are in qualitative\naccord with some but not all aspects of the observed patterns. It is necessary\nto include friction and angular momentum conservation in the simulations to\nachieve quantitative accord with observations. [Abridged]",
        "positive": "Point-defect haloing in curved nematic films: We investigate the correlation between the point disclination energies and\nthe surface curvature modulation of nematic liquid crystal membranes with a\nGaussian bump geometry. Due to the correlation, disclinations feel an\nattractive force that confines them to an annulus region, resulting in a halo\ndistribution around the top of the bump. The halo formation is a direct\nconsequence of the nonzero Gaussian curvature of the bump that affects\npreferable configurations of liquid crystal molecules around the disclination\ncore."
    },
    {
        "anchor": "Nanoscopic Interfacial Hydrogel Viscoelasticity Revealed from Comparison\n  of Macroscopic and Microscopic Rheology: Deviations between macrorheological and particle-based microrheological\nmeasurements are often considered a nuisance and neglected. We study aqueous\npoly(ethylene oxide) (PEO) hydrogels for varying PEO concentrations and chain\nlengths that contain microscopic tracer particles and show that these\ndeviations in fact reveal the nanoscopic viscoelastic properties of the\nparticle-hydrogel interface. Based on the transient Stokes equation, we first\ndemonstrate that the deviations are not due to finite particle radius,\ncompressibility or surface-slip effects. Small-angle neutron scattering rules\nout hydrogel heterogeneities. Instead, we show that a generalized\nStokes-Einstein relation, accounting for a nanoscopic interfacial shell around\ntracers with viscoelastic properties that significantly deviate from bulk,\nconsistently explains our macrorheological and microrheological measurements.\nThe extracted shell diameter is comparable with the PEO end-to-end distance,\nindicating the importance of dangling chain ends. Our methodology reveals the\nnanoscopic interfacial rheology of hydrogels and is generally applicable to\ndifferent kinds of viscoelastic fluids and particles.",
        "positive": "Evaporation-induced temperature gradient in a foam column: Various parameters affect the foam stability: surface and bulk rheology of\nthe solution, gravitational drainage, mechanical vibrations, bubble gas\ncomposition, and also evaporation. Evaporation is often considered through the\nprism of a liquid loss, but it also induces a cooling effect due to the\nenthalpy of vaporization. In this study, we combine a theoretical and\nexperimental approach to explore the temperature field in a foam column\nevaporating from the top. We show that a measurable temperature profile exists\nin this geometry with temperatures at the interface lower than the\nenvironmental temperature by few degrees. We demonstrate that the temperature\nprofile is the result of a balance between the enthalpy of vaporization and\nheat fluxes originating from the thermal conduction of foam and air and the\nthermal radiation. For small foam thicknesses compared to the radius, we found\nthat the temperature gradient is established over the foam thickness while for\nlarge aspect ratios, the gradient is spanning over a lengthscale comparable to\nthe tube radius."
    },
    {
        "anchor": "Acoustical Properties of Superfluid Helium in Confined Geometry: The problem studied in this paper is to obtain the equations describing sound\npropagation in a consolidated porous medium filled with superfluid, determine\nthe elastic coefficients, appearing in the equations, in terms of physically\nmeasurable quantities, and calculate the propagation velocities of transverse\nand longitudinal waves at high and low oscillating frequencies. In general, the\nobtained equations describe all volume modes that can propagate in a porous\nmedium saturated with superfluid for any values of the porosity and\nfrequencies. The derived equations are applied to the most important particular\ncase when the normal component of superfluid helium is locked inside a highly\nporous media (aerogel, Im-helium sample) by viscous forces. For this case the\nvelocities of two longitudinal sound modes and transverse mode are calculated\nfrom the derived equations. There are established the coupling between\ntemperature and pressure oscillations in these fast and slow modes.",
        "positive": "Controlled transitions between phyllotactic states of repulsive\n  particles confined on the surface of a cylinder: Phyllotactic states are regular lattice-like structures on cylinders and are\na botanical classification scheme. In this communication, we report a sequence\nof transitions between phyllotactic states for particles with a repulsive\nparticle-particle interaction on a cylindrical geometry at zero temperature. We\ncan infer the transition points as a function of density via Monte Carlo\nsimulations, as well as the mathematical descriptions of the ground states. The\nlattices we generate are described as phyllotactic states that fit onto the\ncylindrical surface as a set of helical chains. Our analysis shows how all\nstate energies lie on the same parabola which we exploit to find the\ntransitions."
    },
    {
        "anchor": "A Langevin Approach to One-Dimensional Granular Media Fluidized by\n  Vibrations: We present a Langevin approach to describe the steady-state dynamics of\none-dimensional granular media fluidized by a vibrating bottom plate. We adopt\na linear Langevin equation to describe the motion of the center of mass. Within\nthis framework, we derive analytical expressions for several macroscopic\nquantities. We also predict the power spectrum for the height of the center of\nmass. We find good agreement between our theoretical predictions and extensive\nevent-driven molecular dynamics simulations.",
        "positive": "Dissipative particle dynamics simulation of critical pore size in a\n  lipid bilayer membrane: We investigate with computer simulations the critical radius of pores in a\nlipid bilayer membrane. Ilton et al. (2016) recently showed that nucleated\npores in a homopolymer film can increase or decrease in size, depending on\nwhether they are larger or smaller than a critical size which scales linearly\nwith film thickness. Using dissipative particle dynamics, a particle-based\nsimulation method, we investigate the same scenario for a lipid bilayer\nmembrane whose structure is determined by lipid-water interactions. We simulate\na perforated membrane in which holes larger than a critical radius grow, while\nholes smaller than the critical radius close, as in the experiment of Ilton et\nal. (2016). By altering system parameters such as the number of particles per\nlipid and the periodicity, we also describe scenarios in which pores of any\ninitial size can seal or even remain stable, showing a fundamental difference\nin the behavior of lipid membranes from polymer films."
    },
    {
        "anchor": "Microscale solute flow probed with rotating microbead trapped in optical\n  vortex: The dynamics of solute flow in the microscopic chamber can be studied with\noptical tweezers. A method based on the metallic microbeads trapped in the\nfocused optical vortex beam is proposed. This annular beam of a twisted\nwavefront exerts torque on a reflective object placed inside the dark core of\nthe vortex. The induced rotational movement of the bead is sensitive to local\nviscosity changes in the surrounding medium, for example during the ongoing\ndissolution process. Two experimental configurations are described, both\nrelying on tracing the angular velocity of the bead in time. In one-bead\nconfiguration the dynamics of local solute concentration can be studied. In\ntwo-bead case the direction and speed of solute flow can be probed with a\nspatial resolution of single micrometers. We approach the elementary problem of\nsucrose dissolution and diffusion in water. The surprising impression of the\nreverse solute flow was observed. Further experimental investigation led to the\ndiscovery that this phenomenon originates from the sucrose stream-like\ndiffusion in the mid-depth of the measurement chamber. The rotating microbead\nmethod applies for various solid and liquid substances and may become a useful\ntechnique for microfluidics research.",
        "positive": "Onset of Patterns in an Ocillated Granular Layer: Continuum and\n  Molecular Dynamics Simulations: We study the onset of patterns in vertically oscillated layers of\nfrictionless dissipative particles. Using both numerical solutions of continuum\nequations to Navier-Stokes order and molecular dynamics (MD) simulations, we\nfind that standing waves form stripe patterns above a critical acceleration of\nthe cell. Changing the frequency of oscillation of the cell changes the\nwavelength of the resulting pattern; MD and continuum simulations both yield\nwavelengths in accord with previous experimental results. The value of the\ncritical acceleration for ordered standing waves is approximately 10% higher in\nmolecular dynamics simulations than in the continuum simulations, and the\namplitude of the waves differs significantly between the models. The delay in\nthe onset of order in molecular dynamics simulations and the amplitude of noise\nbelow this onset are consistent with the presence of fluctuations which are\nabsent in the continuum theory. The strength of the noise obtained by fit to\nSwift-Hohenberg theory is orders of magnitude larger than the thermal noise in\nfluid convection experiments, and is comparable to the noise found in\nexperiments with oscillated granular layers and in recent fluid experiments on\nfluids near the critical point. Good agreement is found between the mean field\nvalue of onset from the Swift-Hohenberg fit and the onset in continuum\nsimulations. Patterns are compared in cells oscillated at two different\nfrequencies in MD; the layer with larger wavelength patterns has less noise\nthan the layer with smaller wavelength patterns."
    },
    {
        "anchor": "Trajectory Extending Kinetic Monte Carlo Simulations to Evaluate Pure\n  and Gas Mixture Diffusivities through a Dense Polymeric Membrane: With renewed interest in CO2 separations, carbon molecular sieving (CMS)\nmembrane performance evaluation requires diffusion coefficients as inputs to\nhave reliable estimate of the permeability. An optimal material is desired to\nhave both high selectivity and permeability. Gases diffusing through dense, CMS\nand polymeric membranes experience extended sub-diffusive regimes which hinders\nreliable extraction of diffusion coefficients from mean squared displacement\ndata. We improve the sampling of the diffusive landscape by implementing the\ntrajectory extending kinetic Monte Carlo (TEKMC) technique to efficiently\nextend MD trajectories from ns to {\\mu}s timescales. The obtained\nself-diffusion coefficient of pure CO2 in CMS membranes derived from\n6FDA/BPDA-DAM precursor polymer melt is found in agreement with previous\nexperimental findings. We also extend the TEKMC algorithm to evaluate the\nmixture diffusivities in binary mixtures to determine the permselectivity of\nCO2 in CH4 and N2 mixtures. The mixture diffusion coefficient of CO2 ranges\nfrom 1.3-7 x 10^{-6} cm6{2}s^{-1} in binary mixture CO2:CH4 which is\nsignificantly higher than the pure gas diffusion coefficient. Robeson plot\ncomparisons show that the permselectivity obtained from pure gas diffusion data\nare significantly lower than that predicted using mixture diffusivity data.\nSpecifically in the case of the CO2:N2 mixture we find that using mixture\ndiffusivities led to permeslectivites lying above the Robeson limit\nhighlighting the importance of using mixture diffusivity data for an accurate\nevaluation of the membrane performance. Combined with gas solubilities obtained\nfrom grand-canonical Monte Carlo simulations, our work shows that simulations\nwith the TEKMC method can be used to reliably evaluate the performance of\nmaterials for gas separations.",
        "positive": "Properties of the Homogeneous Cooling State of a Gas of Inelastic Rough\n  Particles: In this work we address the question of whether a low-density system composed\nof identical rough particles may reach hydrodynamic states (also called\n\\textit{normal} states), even if energy is not conserved in particle\ncollisions. As a way to measure the ability of the system to present a\nhydrodynamic behavior, we focus on the so-called homogeneous cooling state of\nthe granular gas and look at the corresponding relaxation time as a function of\ninelasticity and roughness. We report computer simulation results of the sixth-\nand eighth-order cumulants of the particle velocity distribution function and\nstudy the influence of roughness on their relaxation times and asymptotic\nvalues. This extends the results of a previous work [Phys. Rev. E \\textbf{89},\n020202(R) (2014], where lower-order cumulants were measured. Our results\nconfirm that the relaxation times are not necessarily longer for stronger\ninelasticities. This implies that inelasticity by itself does not preclude\nhydrodynamics.\n  It is also observed that the cumulants associated with the angular velocity\ndistribution may reach very high values in a certain region of (small)\nroughness and that these maxima coincide with small orientational correlation\npoints."
    },
    {
        "anchor": "Cavitation pressure in liquid helium: Recent experiments have suggested that, at low enough temperature, the\nhomogeneous nucleation of bubbles occurs in liquid helium near the calculated\nspinodal limit. This was done in pure superfluid helium 4 and in pure normal\nliquid helium 3. However, in such experiments, where the negative pressure is\nproduced by focusing an acoustic wave in the bulk liquid, the local amplitude\nof the instantaneous pressure or density is not directly measurable. In this\narticle, we present a series of measurements as a function of the static\npressure in the experimental cell. They allowed us to obtain an upper bound for\nthe cavitation pressure P_cav (at low temperature, P_cav < -2.4 bar in helium\n3, P_cav < -8.0 bar in helium 4). From a more precise study of the acoustic\ntransducer characteristics, we also obtained a lower bound (at low temperature,\nP_cav > -3.0 bar in helium 3, P_cav > - 10.4 bar in helium 4). In this article\nwe thus present quantitative evidence that cavitation occurs at low temperature\nnear the calculated spinodal limit (-3.1 bar in helium 3 and -9.5 bar in helium\n4). Further information is also obtained on the comparison between the two\nhelium isotopes. We finally discuss the magnitude of nonlinear effects in the\nfocusing of a sound wave in liquid helium, where the pressure dependence of the\ncompressibility is large.",
        "positive": "Emergent Hydrodynamic Bound States Between Magnetically Powered\n  Micropropellers: Hydrodynamic interactions (HIs), namely solvent mediated long-range\ninteractions between dispersed particles, play a crucial role in the assembly\nand dynamics of many active systems, from swimming bacteria to swarms of\npropelling microrobots. Here we experimentally demonstrate the emergence of\nlong-living hydrodynamic bound states between model micro-swimmers at low\nReynolds number. A rotating magnetic field forces colloidal hematite\nmicroparticles to translate at a constant and frequency-tunable speed close to\na bounding plane in a viscous fluid. At high driving frequency, HIs dominate\nover magnetic dipolar ones, and close propelling particles couple into bound\nstates by adjusting their translational speed in order to optimize the\ntransport of the pair. The physical system is described by considering the HIs\nwith the boundary surface and the effect of gravity, providing an excellent\nagreement with the experimental data for all the range of parameters explored.\nMoreover, we show that in dense suspensions, these bound states can be extended\nto onedimensional arrays of particles assembled by the sole HIs. Our results\nmanifest the importance of the boundary surface in the interaction and dynamics\nof confined propelling microswimmers."
    },
    {
        "anchor": "Dense colloidal suspensions under time-dependent shear: We consider the nonlinear rheology of dense colloidal suspensions under a\ntime-dependent simple shear flow. Starting from the Smoluchowski equation for\ninteracting Brownian particles advected by shearing (ignoring fluctuations in\nfluid velocity) we develop a formalism which enables the calculation of\ntime-dependent, far-from-equilibrium averages. Taking shear-stress as an\nexample we derive exactly a generalized Green-Kubo relation, and an equation of\nmotion for the transient density correlator, involving a three-time memory\nfunction. Mode coupling approximations give a closed constitutive equation\nyielding the time-dependent stress for arbitrary shear rate history. We solve\nthis equation numerically for the special case of a hard sphere glass subject\nto step-strain.",
        "positive": "Electrolytically Generated Nanobubbles on HOPG Surfaces: Electrolysis of water is employed to produce surface nanobubbles on highly\norientated pyrolytic graphite (HOPG) surfaces. Hydrogen (oxygen) nanobubbles\nare formed when the HOPG surface acts as negative (positive) electrode.\nCoverage and volume of the nanobubbles enhance with increasing voltage. The\nyield of hydrogen nanobubbles is much larger than the yield of oxygen\nnanobubbles. The growth of the individual nanobubbles during the electrolysis\nprocess is recorded in time with the help of AFM measurements and correlated\nwith the total current. Both the size of the individual nanobubbles and the\ntotal current saturate after typical 1 minute; then the nanobubbles are in a\ndynamic equilibrium, meaning that they do not further grow, in spite of ongoing\ngas production and nonzero current. The surface area of nanobubbles shows a\ngood correlation with the nanobubble volume growth rate, suggesting that either\nthe electrolytic gas emerges directly at the nanobubbles' surface, or it\nemerges at the electrode's surface and then diffuses through the nanobubbles'\nsurface. Moreover, the experiments reveal that the time constants of the\ncurrent and the aspect ratio of nanobubbles are the same under all conditions.\nReplacement of pure water by water containing a small amount of sodium chloride\n(0.01 M) allows for larger currents, but qualitatively gives the same results."
    },
    {
        "anchor": "Anomalous elasticity in nematic and smectic elastomer tubule: We study anomalous elasticity in the tubule phases of nematic and smectic\nelastomer membranes, which are flat in one direction and crumpled in another.\nThese phases share the same macroscopic symmetry properties including\nspontaneously-broken in-plane isotropy and hence belong to the same\nuniversality class. Below an upper critical value $D_c =3$ of the membranes'\nintrinsic dimension D, thermal fluctuations renormalize the elasticity with\nrespect to elastic displacements along the tubule axis so that elastic moduli\nfor compression along the tubule axis and for bending the tubule axis become\nlength-scale dependent. This anomalous elasticity belongs to the same\nuniversality class as that of d-dimensional conventional smectics with D taking\non the role of d. For physical tubule, D=2, this anomaly is of power-law type\nand thus might by easier to detect experimentally than the logarithmic anomaly\nin conventional smectics.",
        "positive": "Twist-induced local curvature of filaments in DNA toroids: DNA toroidal bundles form upon condensation of one or multiple DNA filaments.\nDNA filaments in toroidal bundles are hexagonally packed, and collectively\ntwist around the center line of the toroid. In a previous study, we and our\ncoworkers argue that the filaments' curvature locally correlates with their\ndensity in the bundle, with the filaments less closely packed where their\ncurvature appears to be higher. We base our claim on the assumption that twist\nhas a negligible effect on the local curvature of filaments in DNA toroids.\nHowever, this remains to be proven. We fill this gap here, by calculating the\ndistribution of filaments' curvature in a geometric model of twisted toroidal\nbundle, which we use to describe DNA toroids by an appropriate choice of\nparameters. This allows us to substantiate our previous study and suggest\ndirections for future experiments."
    },
    {
        "anchor": "An electrodiffusion model for Jaccard's theory in ice: Jaccards' theory describes the movement of both ionic and Bjerrum defects in\nice. Standard descriptions of the theory are based on a chain model describing\nthe movement of these defects along well-oriented chains of water molecules.\nHowever, this model contains several fundamental contradictions and does not\nresult in the exact equations. We present an alternative model based on the\nelectrodiffusion of the defects. The polarisation of the ice specimen favours\nthese defects orientations that diffuse opposite to the electric drift of the\nsame defect. This straightforward approach not only results in the correct\nequations, it also provides a better understanding of the defects' kinetics.",
        "positive": "Note: Melting criterion for soft particle systems in two dimensions: A simple criterion for melting of two-dimensional crystals with soft\nlong-ranged interactions is proposed. It states that the ratio of the\ntransverse sound velocity of an ideal crystalline lattice to the thermal\nvelocity is a quasi-universal number close to $4.3$ at melting. This criterion\nis arrived by reference to the\nBerezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young theory of two-dimensional\nmelting, combined with the observation that the ratio of\ntransverse-to-longitudinal sound velocities is small in the soft interaction\nlimit. Application of this criteria allows estimating melting lines in a simple\nyet relatively accurate manner. Two-dimensional weakly screened Yukawa systems\nrepresent one relevant example considered."
    },
    {
        "anchor": "Heavy Anionic Complex Creates a Unique Water Structure at a Soft Charged\n  Interface: Ion hydration and interfacial water play crucial roles in numerous phenomena\nranging from biological to industrial systems. Although biologically relevant\n(and mostly smaller) ions have been studied extensively in this context, very\nlittle experimental data exist about molecular scale behavior of heavy ions and\ntheir complexes at interfaces, especially under technologically significant\nconditions. It has recently been shown that PtCl62- complexes adsorb at\npositively charged interfaces in a two-step process that cannot fit into\nwell-known empirical trends, such as Hofmeister series. Here, a combined\nvibrational sum frequency generation and molecular dynamics study reveals that\na unique interfacial water structure is connected to this peculiar adsorption\nbehavior. A novel sub-ensemble analysis of MD simulation results show that\nafter adsorption, PtCl62- complexes partially retain their first and second\nhydration spheres, and it is possible to identify three different types of\nwater molecules around them based on their orientational structures and\nhydrogen bonding strengths. These results have important implications for\nrelating interfacial water structure and hydration enthalpy to the general\nunderstanding of specific ion effects. This in turn influences interpretation\nof heavy metal ion distribution across and reactivity within, liquid\ninterfaces.",
        "positive": "Uniaxial versus Biaxial Pathways in One-Dimensional Cholesteric Liquid\n  Crystals: Cholesteric liquid crystals exhibit great morphological richness of static\nmetastable states. Understanding the transitions between such states is key for\nthe development of switchable devices. We show, using a quasi-one-dimensional\nmodel, that cholesterics exhibit distinct uniaxial and biaxial pathways between\ndistinct minima. We study transitions between different layer numbers and\nprove, and show, that transition states are distinguished either through\nsplay-mediated untwisting, understood through contact topology, or the presence\nof biaxiality. Furthermore we characterise a menagerie of additional saddle\npoints that dictate the connectivity of the solution landscape."
    },
    {
        "anchor": "Microscopic mechanism of tunable thermal conductivity in carbon\n  nanotube-geopolymer nanocomposites: Geopolymer has been considered as a green and low-carbon material with great\npotential application due to its simple synthesis process, environmental\nprotection, excellent mechanical properties, good chemical resistance and\ndurability. In this work, the molecular dynamics simulation is employed to\ninvestigate the effect of the size, content and distribution of carbon\nnanotubes on the thermal conductivity of geopolymer nanocomposites, and the\nmicroscopic mechanism is analyzed by the phonon density of states, phonon\nparticipation ratio and spectral thermal conductivity, etc. The results show\nthat there is a significant size effect in geopolymer nanocomposites system due\nto the carbon nanotubes. In addition, when the content of carbon nanotubes is\n16.5%, the thermal conductivity in carbon nanotubes vertical axial direction\n(4.85 W/(mk)) increases 125.6% compared with the system without carbon\nnanotubes (2.15 W/(mk)). However, the thermal conductivity in carbon nanotubes\nvertical axial direction (1.25 W/(mk)) decreases 41.9%, which is mainly due to\nthe interfacial thermal resistance and phonon scattering at the interfaces. The\nabove results provide theoretical guidance for the tunable thermal conductivity\nin carbon nanotube-geopolymer nanocomposites.",
        "positive": "Measurements of Grain Motion in a Dense, Three-Dimensional Granular\n  Fluid: We have used an NMR technique to measure the short-time, three-dimensional\ndisplacement of grains in a system of mustard seeds vibrated vertically at 15g.\nThe technique averages over a time interval in which the grains move\nballistically, giving a direct measurement of the granular temperature profile.\nThe dense, lower portion of the sample is well described by a recent\nhydrodynamic theory for inelastic hard spheres. Near the free upper surface the\nmean free path is longer than the particle diameter and the hydrodynamic\ndescription fails."
    },
    {
        "anchor": "Capillary attraction induced collapse of colloidal monolayers at fluid\n  interfaces: We investigate the evolution of a system of colloidal particles, trapped at a\nfluid interface and interacting via capillary attraction, as function of the\nrange of the capillary interaction and temperature. We address the collapse of\nan initially homogeneous particle distribution and of a radially symmetric\n(disk--shaped) distribution of finite size, both theoretically by using a\nperturbative approach inspired by cosmological models and numerically by means\nof Brownian dynamics (BD) and dynamical density functional theory (DDFT). The\nresults are summarized in a \"dynamical phase diagram\", describing a smooth\ncrossover from collective (gravitational-like) collapse to local\n(spinodal-like) clustering. In this crossover region, the evolution exhibits a\npeculiar shock wave behavior at the outer rim of the contracting, disk-shaped\ndistribution.",
        "positive": "Hamiltonian Dynamics of the Protein Chain and Normal Modes of\n  Alpha-Helix and Beta-Sheet: We use the torsional angles of the protein chain as generalized coordinates\nin the canonical formalism, derive canonical equations of motion, and\ninvestigate the coordinate dependence of the kinetic energy expressed in terms\nof the canonical momenta. We use the formalism to compute the normal-frequency\ndistributions of the alpha-helix and the beta-sheet, under the assumption that\nthey are stabilized purely through hydrogen bonding. Comparison of their free\nenergies show the existence of a phase transition between the alpha-helix and\nthe beta-sheet at a critical temperature."
    },
    {
        "anchor": "Elastowetting of Soft Hydrogel Spheres: When a soft hydrogel sphere is placed on a rigid hydrophilic substrate, it\nundergoes arrested spreading by forming an axisymmetric foot near the contact\nline, while conserving its global spherical shape. In contrast, liquid water\n(that constitutes greater than 90% of the hydrogel's volume) spreads into a\nthin film on the same surface. We study systematically this elastowetting of\ngel spheres on substrates of different surface energies, and find that their\ncontact angle increases as the work of adhesion between the gel and the\nsubstrate decreases, as one would observe for drops of pure water - albeit\nbeing larger than in the latter case. This difference in the contact angles of\ngel and water appears to be due to the elastic shear stresses that develop in\nthe gel and oppose its spreading. Indeed, by increasing the elastic modulus of\nthe gel spheres, we find that their contact angle also increases. In addition,\nthe length of the contact foot increases with the work of adhesion and sphere\nsize, while it decreases when the elastic modulus of the gel is increased. We\ndiscuss those experimental results in light of a minimal analysis based on\nenergy minimization, volume conservation, and scaling arguments.",
        "positive": "On the dependency of rubber friction on the normal force or load: theory\n  and experiment: In rubber friction studies it is often observed that the kinetic friction\ncoefficient {\\mu} depends on the nominal contact pressure p. We discuss several\npossible origins of the pressure dependency of {\\mu}: (a) saturation of the\ncontact area (and friction force) due to high nominal squeezing pressure, (b)\nnon-linear viscoelasticity, (c) non-randomness in the surface topography, in\nparticular the influence of the skewness of the surface roughness profile, (d)\nadhesion, and (e) frictional heating. We show that in most cases the\nnon-linearity in the {\\mu}(p) relation is mainly due to process (e) (frictional\nheating), which softens the rubber, increases the area of contact, and (in most\ncases) reduces the viscoelastic contribution to the friction. In fact, since\nthe temperature distribution in the rubber at time t depends on on the sliding\nhistory (i.e., on the earlier time t0 < t), the friction coefficient at time t\nwill also depend on the sliding history, i.e. it is, strictly speaking, a time\nintegral operator. The energy dissipation in the contact regions between solids\nin sliding contact can result in high local temperatures which may strongly\naffect the area of real contact and the friction force (and the wear-rate).\nThis is the case for rubber sliding on road surfaces at speeds above 1 mm/s. In\nRef. [14] we have derived equations which describe the frictional heating for\nsolids with arbitrary thermal properties. In this paper the theory is applied\nto rubber friction on road surfaces. Numerical results are presented and\ncompared to experimental data. We observe good agreement between the calculated\nand measured temperature increase."
    },
    {
        "anchor": "Soft Matter Perspective on Protein Crystal Assembly: Crystallography may be the gold standard of protein structure determination,\nbut obtaining the necessary high-quality crystals is also in some ways akin to\nprospecting for the precious metal. The tools and models developed in soft\nmatter physics to understand colloidal assembly offer some insights into the\nproblem of crystallizing proteins. This topical review describes the various\nanalogies that have been made between proteins and colloids in that context. We\nhighlight the explanatory power of patchy particle models, but also the\nchallenges of providing guidance for crystallizing specific proteins. We\nconclude with a presentation of possible future research directions. This\narticle is intended for soft matter scientists interested in protein\ncrystallization as a self-assembly problem, and as an introduction to the\npertinent physics literature for protein scientists more generally.",
        "positive": "On the Behavior of the Lifshitz Line in Ternary\n  Homopolymer/Diblock-Copolymer Blends: We present results of the study of the non-monotonous behavior of the\nLifshitz line as a function of temperature in ternary\nhomopolymer/diblock-copolymer mixtures. The non-monotonous behavior of the\nLifshitz line is due to the wave vector dependence of fluctuational\ncorrections, which we treat in the framework of the renormalization group\nmethod. Our results are in agreement with the experimental findings of Schwahn\net al.[1,2]"
    },
    {
        "anchor": "Flow of colloidal solids and fluids through constrictions: dynamical\n  density functional theory versus simulation: Using both dynamical density functional theory and particle-resolved Brownian\ndynamics simulations, we explore the flow of two-dimensional colloidal solids\nand fluids driven through a linear channel with a geometric constriction. The\nflow is generated by a constant external force acting on all colloids. The\ninitial configuration is equilibrated in the absence of flow and then the\nexternal force is switched on instantaneously. Upon starting the flow, we\nobserve four different scenarios: a complete blockade, a monotonic decay to a\nconstant particle flux (typical for a fluid), a damped oscillatory behaviour in\nthe particle flux, and a long-lived stop-and-go behaviour in the flow (typical\nfor a solid). The dynamical density functional theory describes all four\nsituations but predicts infinitely long undamped oscillations in the flow which\nare always damped in the simulations. We attribute the mechanisms of the\nunderlying stop-and-go flow to symmetry conditions on the flowing solid. Our\npredictions are verifiable in real-space experiments on magnetic colloidal\nmonolayers which are driven through structured microchannels and can be\nexploited to steer the flow throughput in microfluidics.",
        "positive": "Josephson Effect in BEC with Spin Degree of Freedom: We consider the Josephson Effect between two spatially separated\nBose-Einstein condensates of atoms each of which can be in two hyperfine\nstates. We derive simple equations of motion for this system closely analogous\nto the Bloch equations. We also map the dynamics of the system onto those of a\nclassical particle in a well. We find novel density and spin modes of\noscillation and new stable equilibrium points of the motion. Finally we analyze\nthe oscillation modes in the spin-1 ($F$=1) case."
    },
    {
        "anchor": "Blocking of phase transitions in liquid crystal 5*CB\n  (isopentylcyanobiphenyl) as a result of surface interactions at the\n  nano-membranes: In this paper we present results of dielectric measurements of the liquid\ncrystal (LC) 5*CB arranged in the porous matrices with a pore diameter of 100\nand 20nm. We analyze the effect of surface interactions on the dynamics of\nmolecules. The results were compared with the results of the bulk 5*CB. The\nmost important result is the blocking of phase transition of 5*CB into the\nsolid phase in a matrix of 20 nm.",
        "positive": "Chirality transfer and stereo-selectivity of imprinted cholesteric\n  networks: Imprinting of cholesteric textures in a polymer network is a method of\npreserving a macroscopically chiral phase in a system with no molecular\nchirality. By modifying the elastics properties of the network, the resulting\nstored helical twist can be manipulated within a wide range since the\nimprinting efficiency depends on the balance between the elastics constants and\ntwisting power at network formation. One spectacular property of phase\nchirality imprinting is the created ability of the network to adsorb\npreferentially one stereo-component from a racemic mixture. In this paper we\nexplore this property of chirality transfer from a macroscopic to the molecular\nscale. In particular, we focus on the competition between the phase chirality\nand the local nematic order. We demonstrate that it is possible to control the\nsubsequent release of chiral solvent component from the imprinting network and\nthe reversibility of the stereo-selective swelling by racemic solvents."
    },
    {
        "anchor": "Soft Active Matter: In this review we summarize theoretical progress in the field of active\nmatter, placing it in the context of recent experiments. Our approach offers a\nunified framework for the mechanical and statistical properties of living\nmatter: biofilaments and molecular motors in vitro or in vivo, collections of\nmotile microorganisms, animal flocks, and chemical or mechanical imitations. A\nmajor goal of the review is to integrate the several approaches proposed in the\nliterature, from semi-microscopic to phenomenological. In particular, we first\nconsider \"dry\" systems, defined as those where momentum is not conserved due to\nfriction with a substrate or an embedding porous medium, and clarify the\ndifferences and similarities between two types of orientationally ordered\nstates, the nematic and the polar. We then consider the active hydrodynamics of\na suspension, and relate as well as contrast it with the dry case. We further\nhighlight various large-scale instabilities of these nonequilibrium states of\nmatter. We discuss and connect various semi-microscopic derivations of the\ncontinuum theory, highlighting the unifying and generic nature of the continuum\nmodel. Throughout the review, we discuss the experimental relevance of these\ntheories for describing bacterial swarms and suspensions, the cytoskeleton of\nliving cells, and vibrated granular materials. We suggest promising extensions\ntowards greater realism in specific contexts from cell biology to ethology, and\nremark on some exotic active-matter analogues. Lastly, we summarize the outlook\nfor a quantitative understanding of active matter, through the interplay of\ndetailed theory with controlled experiments on simplified systems, with living\nor artificial constituents.",
        "positive": "Continuum random sequential adsorption of polymer on a flat and\n  homogeneous surface: Random sequential adsorption (RSA) of polymer, modeled as a chain of\nidentical spheres, is systematically studied. In order to control precisely\nanisotropy and number of degrees of freedom, two different kinds of polymers\nare used. In the first one, monomers are placed along a straight line, whereas\nin the second, relative orientations of particles are random. Such polymers\nfill a flat homogeneous surface randomly. The paper focuses on maximal random\ncoverage ratio and adsorption kinetics dependence on polymer size, shape\nanisotropy, and numbers of degrees of freedom. Obtained results were discussed\nand compared with other numerical experiments and theoretical predictions."
    },
    {
        "anchor": "Phase resolution limit in macroscopic interference between Bose-Einstein\n  condensates: We study the competition between phase definition and quantum phase\nfluctuations in interference experiments between independently formed Bose\ncondensates. While phase-sensitive detection of atoms makes the phase\nprogressively better defined, interactions tend to randomize it faster as the\nuncertainty in the relative particle number grows. A steady state is reached\nwhen the two effects cancel each other. Then the phase resolution saturates to\na value that grows with the ratio between the interaction strength and the atom\ndetection rate, and the average phase and number begin to fluctuate\nclassically. We discuss how our study applies to both recently performed and\npossible future experiments.",
        "positive": "Dielectrophoresis of nanoscale dsDNA and humidity effects on its\n  electrical conductivity: The dielectrophoresis method for trapping and attaching nanoscale\ndouble-stranded DNA between nanoelectrodes was developed. The method gives a\nhigh yield of trapping single or a few molecules only which enables transport\nmeasurements at the single molecule level. Electrical conductivity of\nindividual 140-nm-long DNA molecules was measured, showing insulating behavior\nin dry conditions. In contrast, clear enhancement of conductivity was observed\nin moist conditions, relating to the interplay between the conformation of DNA\nmolecules and their conductivity."
    },
    {
        "anchor": "Large-Scale Simulations of the Two-Dimensional Melting of Hard Disks: Large-scale computer simulations involving more than a million particles have\nbeen performed to study the melting transition in a two-dimensional hard disk\nfluid. The van der Waals loop previously observed in the pressure-density\nrelationship of smaller simulations is shown to be an artifact of finite-size\neffects. Together with a detailed scaling analysis of the bond orientation\norder, the new results provide compelling evidence for the\nHalperin-Nelson-Young picture. Scaling analysis of the translational order also\nyields a lower bound for the melting density that is much higher than\npreviously thought.",
        "positive": "Active microrheology in the continuum limit: can the macrorheology be\n  recovered?: Active microrheology differs from its passive counterpart in that the probe\nis actively forced through the material, rather than allowed to diffuse. Unlike\nin passive microrheology, active forcing allows the material to be driven out\nof equilibrium, and its nonlinear response to be probed. However, this also\nrenders inoperable the fluctuation-dissipation theorem used to justify passive\nmicrorheology. Here we explore a question at the heart of active microrheology:\nare its results consistent with macrorheology? We study a simple model material\n-- a generalized Newtonian fluid, with a small but arbitrary\nshear-rate-dependent component -- and derive a general expression for\ndissipation due to probe motion, which remarkably does not require the\nnon-Newtonian flow to be solved. We demonstrate that the straightforward\napplication of active microrheology gives results that are inconsistent with\nmacrorheology, even when the probe is large enough for material to behave as a\ncontinuum, unless the forcing is gentle enough to probe only the linear\nresponse. Regardless, each technique encodes information about the material; if\nsuitably interpreted, the (macro-) constitutive relation can indeed be\nrecovered from the microrheological data. We emphasize that more, rather than\nless, information would be obtained if the two methods disagree."
    },
    {
        "anchor": "Comparison of Dissipative Particle Dynamics and Langevin thermostats for\n  out-of-equilibrium simulations of polymeric systems: In this work we compare and characterize the behavior of Langevin and\nDissipative Particle Dynamics (DPD) thermostats in a broad range of\nnon-equilibrium simulations of polymeric systems. Polymer brushes in relative\nsliding motion, polymeric liquids in Poiseuille and Couette flows, and\nbrush-melt interfaces are used as model systems to analyze the efficiency and\nlimitations of different Langevin and DPD thermostat implementations. Widely\nused coarse-grained bead-spring models under good and poor solvent conditions\nare employed to assess the effects of the thermostats. We considered\nequilibrium, transient, and steady state examples for testing the ability of\nthe thermostats to maintain constant temperature and to reproduce the\nunderlying physical phenomena in non-equilibrium situations. The common\npractice of switching-off the Langevin thermostat in the flow direction is also\ncritically revisited. The efficiency of different weight functions for the DPD\nthermostat is quantitatively analyzed as a function of the solvent quality and\nthe non-equilibrium situation.",
        "positive": "Interaction between like-charged polyelectrolyte-colloid complexes in\n  electrolyte solutions: a Monte Carlo simulation study in the Debye-H\u00fcckel\n  approximation: We study the effective interaction between differently charged\npolyelectrolyte-colloid complexes in electrolyte solutions via Monte Carlo\nsimulations. These complexes are formed when short and flexible polyelectrolyte\nchains adsorb onto oppositely charged colloidal spheres, dispersed in an\nelectrolyte solution. In our simulations the bending energy between adjacent\nmonomers is small compared to the electrostatic energy, and the chains, once\nadsorbed, do not exchange with the solution, although they rearrange on the\nparticles surface to accomodate further adsorbing chains or due to the\nelectrostatic interaction with neighbor complexes. Rather unexpectedly, when\ntwo interacting particles approach each others, the rearrangement of the\nsurface charge distribution invariably produces anti-parallel dipolar doublets,\nthat invert their orientation at the isoelectric point. These findings clearly\nrule out a contribution of dipole-dipole interactions to the observed\nattractive interaction between the complexes, pointing out that such\nsuspensions can not be considered dipolar fluids. On varying the ionic strength\nof the electrolyte, we find that a screening length, short compared with the\nsize of the colloidal particles, is required in order to observe the attraction\nbetween like charged complexes due to the non-uniform distribution of the\nelectric charge on their surface ('patch attraction'). On the other hand, by\nchanging the polyelectrolyte/particle charge ratio, the interaction between\nlike-charged polyelectrolyte-decorated (pd) particles, at short separations,\nevolves from purely repulsive to strongly attractive. Hence, the effective\ninteraction between the complexes is characterized by a potential barrier,\nwhose height depends on the net charge and on the non-uniformity of their\nsurface charge distribution."
    },
    {
        "anchor": "Twist-bend coupling and the torsional response of double-stranded DNA: Recent magnetic tweezers experiments have reported systematic deviations of\nthe twist response of double-stranded DNA from the predictions of the twistable\nworm-like chain model. Here we show, by means of analytical results and\ncomputer simulations, that these discrepancies can be resolved if a coupling\nbetween twist and bend is introduced. We obtain an estimate of 40 $\\pm$ 10 nm\nfor the twist-bend coupling constant. Our simulations are in good agreement\nwith high-resolution, magnetic-tweezers torque data. Although the existence of\ntwist-bend coupling was predicted long ago (Marko and Siggia, Macromolecules\n27, 981 (1994)), its effects on the mechanical properties of DNA have been so\nfar largely unexplored. We expect that this coupling plays an important role in\nseveral aspects of DNA statics and dynamics.",
        "positive": "Biofilm growth on rugose surfaces: A stochastic model is used to assess the effect of external parameters on the\ndevelopment of submerged biofilms on smooth and rough surfaces. The model\nincludes basic cellular mechanisms, such as division and spreading, together\nwith an elementary description of the interaction with the surrounding flow and\nprobabilistic rules for EPS matrix generation, cell decay and adhesion. Insight\non the interplay of competing mechanisms as the flow or the nutrient\nconcentration change is gained. Erosion and growth processes combined produce\nbiofilm structures moving downstream. A rich variety of patterns are generated:\nshrinking biofilms, patches, ripple-like structures traveling downstream,\nfingers, mounds, streamer-like patterns, flat layers, porous and dendritic\nstructures. The observed regimes depend on the carbon source and the type of\nbacteria."
    },
    {
        "anchor": "Thermal fluctuations of free standing graphene: We use non-perturbative renormalization group techniques to calculate the\nmomentum dependence of thermal fluctuations of graphene, based on a\nself-consistent calculation of the momentum dependent elastic constants of a\ntethered membrane. We find a sharp crossover from the perturbative to the\nanomalous regime, in excellent agreement with Monte Carlo results for graphene,\nand give an accurate value for the crossover scale. Our work strongly supports\nthe notion that graphene is well described as a tethered membrane. Ripples\nemerge naturally from our analysis.",
        "positive": "Fractional Debye-Stokes-Einstein behaviour in an ultraviscous\n  nanocolloid: glycerol and silver nanoparticles: One of hallmark features of glass forming ultraviscous liquids is the\ndecoupling between translational and orientational dynamics. This report\npresents studies of this phenomenon in glycerol, a canonical molecular glass\nformer, heading for the impact of two exogenic factors: high pressures up to\nextreme 1.5 GPa and silver (Ag) nanoparticles (NP). The analysis is focused on\nthe fractional Debye-Stokes-Einstein (FDSE) relation $\\sigma(T,P)*(\\tau(T,P))^S\n= const$, linking DC electric conductivity $(\\sigma)$ and primary $(\\alpha)$\nrelaxation time $(\\tau_\\alpha)$. In glycerol and its nanocolloid (glycerol with\nAg-NP) under atmospheric pressure only the negligible decoupling $(S = 1)$ was\ndetected. However, in the compressed nanocolloid a well-defined transformation\n(at P = 1.2 GPa) from $S \\thickapprox 1$ to the very strongly decoupled\ndynamics $(S \\thickapprox 0.5)$ occurred. For comparison, in pressurized 'pure'\nglycerol the stretched shift from $S \\thickapprox 1$ to $S \\thickapprox 0.7$\ntook place. This report presents also the general discussion of FDSE behavior\nin ultraviscous liquids, including the new link between FDSE exponent,\nfragility and the apparent activation enthalpy and volume."
    },
    {
        "anchor": "Transfer Learning Facilitates the Prediction of Polymer-Surface Adhesion\n  Strength: Machine learning (ML) accelerates the exploration of material properties and\ntheir links to the structure of the underlying molecules. In previous work [J.\nShi, M. J. Quevillon, P. H. A. Valen\\c{c}a, and J. K. Whitmer, \\textit{ACS\nAppl. Mater. Interfaces.}, 2022, 14, 32, 37161--37169], ML models were applied\nto predict the adhesive free energy of polymer--surface interactions with high\naccuracy from the knowledge of the sequence data, demonstrating successes in\ninverse-design of polymer sequence for known surface compositions. While the\nmethod was shown to be successful in designing polymers for a known surface,\nextensive datasets were needed for each specific surface in order to train the\nsurrogate models. Ideally, one should be able to infer information about\nsimilar surfaces without having to regenerate a full complement of adhesion\ndata for each new case. In the current work, we demonstrate a transfer learning\n(TL) technique using a deep neural network to improve the accuracy of ML models\ntrained on small datasets by pre-training on a larger database from a related\nsystem and fine-tuning the weights of all layers with a small amount of\nadditional data. The shared knowledge from the pre-trained model facilitates\nthe prediction accuracy significantly on small datasets. We also explore the\nlimits of database size on accuracy and the optimal tuning of network\narchitecture and parameters for our learning tasks. While applied to a\nrelatively simple coarse-grained (CG) polymer model, the general lessons of\nthis study apply to detailed modeling studies and the broader problems of\ninverse materials design.",
        "positive": "Phase classification using neural networks: application to supercooled,\n  polymorphic core-softened mixtures: Characterization of phases of soft matter systems is a challenge faced in\nmany physicochemical problems. For polymorphic fluids it is an even greater\nchallenge. Specifically, glass forming fluids, as water, can have, besides\nsolid polymorphism, more than one liquid and glassy phases, and even a\nliquid-liquid critical point. In this sense, we apply a neural network (NN)\nalgorithm to analyze the phase behavior of a core-softened mixture of\ncore-softened CSW fluids that have liquid polymorphism and liquid-liquid\ncritical points, similar to water. We also apply the NN to mixtures of CSW\nfluids and core-softened alcohols models. We combine and expand two methods\nbased on bond-orientational order parameters to study mixtures, applied to\nmixtures of hardcore fluids by Boattini and co-authors [Molecular Physics 116,\n3066-3075 (2018)] and to supercooled water by Martelli and co-authors [The\nJournal of Chemical Physics 153, 104503 (2020)], to include longer range\ncoordination shells. With this, the trained neural network (NN) was able to\nproperly predict the crystalline solid phases, the fluid phases and the\namorphous phase for the pure CSW and CSW-alcohols mixtures with high\nefficiency. More than this, information about the phase populations, obtained\nfrom the NN approach, can help verify if the phase transition is continuous or\ndiscontinuous, and also to interpret how the metastable amorphous region\nspreads along the stable high density fluid phase. These findings help to\nunderstand the behavior of supercooled polymorphic fluids and extend the\ncomprehension of how amphiphilic solutes affect the phases behavior."
    },
    {
        "anchor": "Understanding, Quantifying, and Controlling the Molecular Ordering of\n  Semi-conducting Polymers: From Novices to Experts and Amorphous to Perfect\n  Crystals: Molecular packing, crystallinity, and texture of semiconducting polymers are\noften critical to performance. Although frame-works exist to quantify the\nordering, interpretations are often just qualitative, resulting in imprecise\nand liberal use of terminology. Here, we reemphasize the continuity of the\ndegree of molecular ordering and advocate that a more nuanced and consistent\nterminology is used with regards to crystallinity, semicyrstallinity,\nparacrystallinity, crystallite/aggregate, and related characteristics. We are\nmotivated in part by our own imprecise and inconsistent use of terminology and\nthe need to have a primer or tutorial reference to teach new group members. We\nshow that a deeper understanding can be achieved by combining grazing-incidence\nwide-angle X-ray scattering and differential scanning calorimetry. We classify\na broad range of representative polymers into four proposed categories based on\nthe quantitative analysis of molecular order based on the paracrystalline\ndisorder parameter (g). A small database is presented for over 10\nrepresentative conjugated and insulating polymers ranging from amorphous to\nsemicrystalline. Finally, we outline the challenges to rationally design\nperfect polymer crystals and propose a new molecular design approach that\nenvisions conceptual molecular grafting that is akin to strained and unstrained\nhetero-epitaxy in classic (compound) semiconductors thin film growth.",
        "positive": "Three-body interactions in colloidal systems: We present the first direct measurement of three-body interactions in a\ncolloidal system comprised of three charged colloidal particles. Two of the\nparticles have been confined by means of a scanned laser tweezers to a\nline-shaped optical trap where they diffused due to thermal fluctuations. Upon\nthe approach of a third particle, attractive three-body interactions have been\nobserved. The results are in qualitative agreement with additionally performed\nnonlinear Poissson-Boltzmann calculations, which also allow us to investigate\nthe microionic density distributions in the neighborhood of the interacting\ncolloidal particles."
    },
    {
        "anchor": "Collision of viscoelastic bodies: Rigorous derivation of dissipative\n  force: We report a new theory of dissipative forces acting between colliding\nviscoelastic bodies. The impact velocity is assumed not to be large, to avoid\nplastic deformations and fragmentation at the impact. The bodies may be of an\narbitrary convex shape and of different materials. We develop a mathematically\nrigorous perturbation scheme to solve the continuum mechanics equation that\ndeals with both displacement and displacement rate fields and accounts for the\ndissipation in the bulk of the material. The perturbative solution of this\nequation allows to go beyond the previously used quasi-static approximation and\nobtain the dissipative force. This force does not suffer from the physical\ninconsistencies of the latter approximation and depends on particle deformation\nand deformation rate.",
        "positive": "Implementation and performance analysis of bridging Monte Carlo moves\n  for off-lattice single chain polymers in globular states: Bridging algorithms are global Monte Carlo moves which allow for an efficient\nsampling of single polymer chains. In this manuscript we discuss the adaptation\nof three bridging algorithms from lattice to continuum models, and give details\non the corrections to the acceptance rules which are required to fulfill\ndetailed balance. For the first time we are able to compare the efficiency of\nthe moves by analyzing the occurrence of knots in globular states. For a\nflexible homopolymer chain of length N=1000, independent configurations can be\ngenerated up to two orders of magnitude faster than with slithering snake\nmoves."
    },
    {
        "anchor": "Depletion-Induced Forces and Crowding in Polymer-Nanoparticle Mixtures:\n  Role of Polymer Shape Fluctuations and Penetrability: Depletion forces and macromolecular crowding govern the structure and\nfunction of biopolymers in biological cells and the properties of polymer\nnanocomposite materials. To isolate and analyze the influence of polymer shape\nfluctuations and penetrability on depletion-induced interactions and crowding\nby nanoparticles, we model polymers as effective penetrable ellipsoids, whose\nshapes fluctuate according to the probability distributions of the eigenvalues\nof the gyration tensor of an ideal random walk. Within this model, we apply\nMonte Carlo simulation methods to compute the depletion-induced potential of\nmean force between hard nanospheres and crowding-induced shape distributions of\npolymers in the protein limit, in which polymer coils can be easily penetrated\nby smaller nanospheres. By comparing depletion potentials from simulations of\nellipsoidal and spherical polymer models with predictions of polymer field\ntheory and free-volume theory, we show that polymer depletion-induced\ninteractions and crowding depend sensitively on polymer shapes and\npenetrability, with important implications for bulk thermodynamic phase\nbehavior.",
        "positive": "Broken living layers: dislocations in active smectics: We show that dislocations in active 2d smectics with underlying rotational\nsymmetry are always unbound in the presence of noise, meaning the active\nsmectic phase does not exist for non-zero noise in $d=2$. The active smectic\nphase can, like equilibrium smectics in 2d, be stabilized by applying\nrotational symmetry breaking fields; however, even in the presence of such\nfields, active smectics are still much less stable against noise than\nequilibrium ones, when the symmetry breaking field(s) are weak."
    },
    {
        "anchor": "Electric energies of a charged sphere surrounded by electrolyte: By using the generalized version of the Shell Theorem analytical equations\nare derived to calculate the electric energy of a charged sphere and the field\nenergy of the electrolyte inside and around the sphere. These electric energies\nare calculated as a function of the ion concentration of the electrolyte. The\nwork needed to build up the charged sphere (i.e. the total charge-charge\ninteraction energy) decreases with increasing ion concentration of the\nelectrolyte because of the screening effect of the electrolyte on the\ncharge-charge interaction. The energy needed to build up the charged sphere\nappears as sum of the field energy of the electrolyte and the polarization\nenergy of the electrolyte ions. At zero ion concentration the field energy of\nthe electrolyte is equal with the charge-charge interaction energy, while the\npolarization energy is zero. At high ion concentrations 50% of the\ncharge-charge interaction energy appears as the polarization energy of ions,\n25% as the field energy of the electrolyte inside the sphere and 25% as the\nfield energy of the electrolyte around the sphere.",
        "positive": "Influence of constraints on axial growth reduction of cylindrical Li-ion\n  battery electrode particles: Volumetric expansion of silicon anode particles in a lithium-ion battery\nduring charging may lead to the generation of undesirable internal stresses.\nFor a cylindrical particle such growth may also lead to failure by buckling if\nthe expansion is constrained in the axial direction due to other particles or\nsupporting structures. To mitigate this problem, the possibility of reducing\naxial growth is investigated theoretically by studying simple modifications of\nthe solid cylinder geometry. First, an annular cylinder is considered with\nlithiation either from the inside or from the outside. In both cases, the\nreduction of axial growth is not found to be significant. Next, explicit\nphysical constraints are studied by addition of a non-growing elasto-plastic\nmaterial: first, an outer annular constraint on a solid silicon cylinder, and\nsecond a rod-like inner constraint for an annular silicon cylinder. In both\ncases, it is found that axial growth can be reduced if the yield stress of the\nconstraining material is significantly higher than that of silicon and/or the\nthickness of the constraint is relatively high. Phase diagrams are presented\nfor both the outer and the inner constraint cases to identify desirable\noperating zones. Finally, to interpret the phase diagrams and isolate the key\nphysical principles two different simplified models are presented and are shown\nto recover important qualitative trends of the numerical simulation results."
    },
    {
        "anchor": "Bicontinuous emulsions stabilized solely by colloidal particles: Recent large-scale computer simulations suggest that it may be possible to\ncreate a new class of soft solids, called `bijels', by stabilizing and\narresting the bicontinuous interface in a binary liquid demixing via spinodal\ndecomposition using particles that are neutrally wetted by both liquids. The\ninterfacial layer of particles is expected to be semi-permeable, hence, if\nrealised, these new materials would have many potential applications, e.g. as\nmicroreaction media. However, the creation of bijels in the laboratory faces\nserious obstacles. In general, fast quench rates are necessary to bypass\nnucleation, so that only samples with limited thickness can be produced, which\ndestroys the three-dimensionality of the putative bicontinuous network.\nMoreover, even a small degree of unequal wettability of the particles by the\ntwo liquids can lead to ill-characterised, `lumpy' interfacial layers and\ntherefore irreproducible material properties. Here we report a reproducible\nprotocol for creating three-dimensional samples of bijel in which the\ninterfaces are stabilized by essentially a single layer of particles. We\ndemonstrate how to tune the mean interfacial separation in these bijels, and\nshow that mechanically, they indeed behave as soft solids.",
        "positive": "Ordering transitions of weakly anisotropic hard rods in narrow slit-like\n  pores: The effect of strong confinement on the positional and orientational ordering\nis examined in a system of hard rectangular rods with length L and diameter D\n(L>D) using the Parsons-Lee modification of the second virial density\nfunctional theory. The rods are nonmesogenic (L/D<3)and confined between two\nparallel hard walls, where the width of the pore (H) is chosen in such a way\nthat both planar (particle's long axis parallel to the walls) and homeotropic\n(particle's long axis perpendicular to the walls) orderings are possible and a\nmaximum of two layers are allowed to form in the pore. In the extreme\nconfinement limit of ,where only one layer structures appear, we observe a\nstructural transition from a planar to a homeotropic fluid layer with\nincreasing density, which becomes sharper as L->H. In wider pores (2D<H<3D)\nplanar order with two layers, homeotropic order, and even combined bilayer\nstructures (one layer is homeotropic, while the other is planar) can be\nstabilized at high densities. Moreover, first order phase transitions can be\nseen between different structures. One of them emerges between a monolayer and\na bilayer with planar orders at relatively low packing fractions."
    },
    {
        "anchor": "Enhanced diffusion and enzyme dissociation: The concept that catalytic enzymes can act as molecular machines transducing\nchemical activity into motion has conceptual and experimental support, but much\nof the claimed support comes from experimental conditions where the substrate\nconcentration is higher than biologically relevant and accordingly exceeds kM,\nthe Michaelis-Menten constant. Moreover, many of the enzymes studied\nexperimentally to date are oligomeric. Urease, a hexamer of subunits, has been\nconsidered to be the gold standard demonstrating enhanced diffusion. Here we\nshow that urease and certain other oligomeric enzymes of high catalytic\nactivity above kM dissociate into their smaller subunit fragments that diffuse\nmore rapidly, thus providing a simple physical mechanism of enhanced diffusion\nin this regime of concentrations. Mindful that this conclusion may be\ncontroversial, our findings are sup-ported by four independent analytical\ntechniques, static light scattering, dynamic light scattering (DLS),\nsize-exclusion chroma-tography (SEC), and fluorescence correlation spectroscopy\n(FCS). Data for urease are presented in the main text and the con-clusion is\nvalidated for hexokinase and acetylcholinesterase with data presented in\nsupplementary information. For substrate concentration regimes below kM at\nwhich these enzymes do not dissociate, our findings from both FCS and DLS\nvalidate that enzymatic catalysis does lead to the enhanced diffusion\nphenomenon. INTRODUCT",
        "positive": "Stability of smectic phases in hard-rod mixtures: Using density-functional theory, we have analyzed the phase behavior of\nbinary mixtures of hard rods of different lengths and diameters. Previous\nstudies have shown a strong tendency of smectic phases of these mixtures to\nsegregate and, in some circumstances, to form microsegregated phases. Our focus\nin the present work is on the formation of columnar phases which some studies,\nunder some approximations, have shown to become thermodynamically stable prior\nto crystallization. Specifically we focus on the relative stability between\nsmectic and columnar phases, a question not fully addressed in previous work.\nOur analysis is based on two complementary perspectives: on the one hand, an\nextended Onsager theory, which includes the full orientational degrees of\nfreedom but with spatial and orientational correlations being treated in an\napproximate manner; on the other hand, we formulate a Zwanzig approximation of\nfundamental-measure theory on hard parallelepipeds, whereby orientations are\nrestricted to be only along three mutually orthogonal axes, but correlations\nare faithfully represented. In the latter case novel, complete phase diagrams\ncontaining regions of stability of liquid-crystalline phases are calculated.\nOur findings indicate that the restricted-orientation approximation enhances\nthe stability of columnar phases so as to preempt smectic order completely\nwhile, in the framework of the extended Onsager model, with full orientational\ndegrees of freedom taken into account, columnar phases may preempt a large\nregion of smectic stability in some mixtures, but some smectic order still\npersists."
    },
    {
        "anchor": "Stationary quantum statistics of a non-Markovian atom laser: We present a steady state analysis of a quantum-mechanical model of an atom\nlaser. A single-mode atomic trap coupled to a continuum of external modes is\ndriven by a saturable pumping mechanism. In the dilute flux regime, where\natom-atom interactions are negligible in the output, we have been able to solve\nthis model without making the Born-Markov approximation. The more exact\ntreatment has a different effective damping rate and occupation of the lasing\nmode, as well as a shifted frequency and linewidth of the output. We examine\ngravitational damping numerically, finding linewidths and frequency shifts for\na range of pumping rates. We treat mean field damping analytically, finding a\nmemory function for the Thomas-Fermi regime. The occupation and linewidth are\nfound to have a nonlinear scaling behavior which has implications for the\nstability of atom lasers.",
        "positive": "Singular perturbation analysis of a reduced model for collective motion:\n  A renormalization group approach: In a system of noisy self-propelled particles with interactions that favor\ndirectional alignment, collective motion will appear if the density of\nparticles is beyond a critical density. Starting with a reduced model for\ncollective motion, we determine how the critical density depends on the form of\nthe initial perturbation. Specifically, we employ a renormalization-group\nimproved perturbative method to analyze the model equations, and show\nanalytically, up to first order in the perturbation parameter, how the critical\ndensity is modified by the strength of the initial angular perturbation in the\nsystem."
    },
    {
        "anchor": "Two-dimensional melting under quenched disorder: We study the influence of quenched disorder on the two-dimensional melting\nbehavior by using both video-microscopy of superparamagnetic colloidal\nparticles and computer simulations of repulsive parallel dipoles. Quenched\ndisorder is provided by pinning a fraction of the particles. We confirm the\noccurrence of the Kosterlitz-Thouless-Halperin-Nelson-Young scenario with an\nintermediate hexatic phase. While the fluid-hexatic transition remains largely\nunaffected by disorder, the hexatic-solid transition shifts towards lower\ntemperatures for increasing disorder resulting in a significantly broadened\nstability range of the hexatic phase. In addition, we observe spatio-temporal\ncritical(-like) fluctuations consistent with the continuous character of the\nphase transitions.",
        "positive": "Identifying Proteins of High Designability via Surface-Exposure Patterns: Using an off-lattice model, we fully enumerate folded conformations of\npolypeptide chains of up to N = 19 monomers. Structures are found to differ\nmarkedly in designability, defined as the number of sequences with that\nstructure as a unique lowest-energy conformation. We find that designability is\nclosely correlated with the pattern of surface exposure of the folded\nstructure. For longer chains, complete enumeration of structures is\nimpractical. Instead, structures can be randomly sampled, and relative\ndesignability estimated either from designability within the random sample, or\ndirectly from surface-exposure pattern. We compare the surface-exposure\npatterns of those structures identified as highly designable to the patterns of\nnaturally occurring proteins."
    },
    {
        "anchor": "Theory and Simulation of Multiphase Polymer Systems: The theory of multiphase polymer systems has a venerable tradition. The\n'classical' theory of polymer demixing, the Flory-Huggins theory, was developed\nalready in the forties of the last century. It is still the starting point for\nmost current approaches -- be they improved theories for polymer\n(im)miscibility that take into account the microscopic structure of blends more\naccurately, or sophisticated field theories that allow to study inhomogeneous\nmulticomponent systems of polymers with arbitrary architectures in arbitrary\ngeometries. In contrast, simulations of multiphase polymer systems are\nrelatively young. They are still limited by the fact that one must simulate a\nlarge number of large molecules in order to obtain meaningful results. Both\npowerful computers and smart modeling and simulation approaches are necessary\nto overcome this problem.\n  This article gives an overview over the state-of-the art in both areas,\ntheory and simulation. While the theory has reached a fairly mature stage by\nnow, and many aspects of it are covered in textbooks on polymer physics, the\ninformation on simulations is much more scattered. This is why some effort has\nbeen invested into putting together a representative list of references in this\narea (up to the year of 2008) -- which is of course still far from complete.",
        "positive": "On the origine of the Boson peak: We show that the phonon-saddle transition in the ensemble of generalized\ninherent structures (minima and saddles) happens at the same point as the\ndynamical phase transition in glasses, that has been studied in the framework\nof the mode coupling approximation. The Boson peak observed in glasses at low\ntemperature is a remanent of this transition."
    },
    {
        "anchor": "Non-equilibrium fluctuations and mechanochemical couplings of a\n  molecular motor: We investigate theoretically the violations of Einstein and Onsager\nrelations, and the efficiency for a single processive motor operating far from\nequilibrium using an extension of the two-state model introduced by Kafri {\\em\net al.} [Biophys. J. {\\bf 86}, 3373 (2004)]. With the aid of the Fluctuation\nTheorem, we analyze the general features of these violations and this\nefficiency and link them to mechanochemical couplings of motors. In particular,\nan analysis of the experimental data of kinesin using our framework leads to\ninteresting predictions that may serve as a guide for future experiments.",
        "positive": "Tight packing of a flexible rod in two-dimensional cavities: The present work deals with the injection and packing of a flexible polymeric\nrod of length $L$ into a simply connected rectangular domain of area $XY$. As\nthe injection proceeds, the rod bends over itself and it stores elastic energy\nin closed loops. In a typical experiment $N$ of these loops can be identified\ninside the cavity in the jammed state. We have performed an extensive\nexperimental analysis of the total length $L(N, X, Y)$ in the tight packing\nlimit, and have obtained robust power laws relating these variables.\nAdditionally, we have examined a version of this packing problem when the\nsimply connected domain is partially occupied with free discs of fixed size.\nThe experimental results were obtained with 27 types of cavities and obey a\nsingle equation of state valid for the tight packing of rods in domains of\ndifferent topologies. Besides its intrinsic theoretical interest and\ngenerality, the problem examined here could be of interest in a number of\nstudies including packing models of DNA and polymers in several complex\nenvironments."
    },
    {
        "anchor": "Influence of system size on the properties of a fluid adsorbed in a\n  nanopore: Physical manifestations and methodological consequences: We consider the theoretical description of a fluid adsorbed in a nanopore.\nHysteresis and discontinuities in the isotherms in general hampers the\ndetermination of equilibrium thermodynamic properties, even in computer\nsimulations. A proposed way around this has been to consider both a reservoir\nof small size and a pore of small extent in order to restrict the fluctuations\nof density and approach a classical van der Waals loop. We assess this\nsuggestion by thoroughly studying through density functional theory and Monte\nCarlo simulations the influence of system size on the equilibrium\nconfigurations of the adsorbed fluid and on the resulting isotherms. We stress\nthe importance of pore-symmetry-breaking states that even for modest pore sizes\nlead to discontinuous isotherms and we discuss the physical relevance of these\nstates and the methodological consequences for computing thermodynamic\nquantities.",
        "positive": "Delocalized Electronic Excitations and their Role in Directional Charge\n  Transfer in the Reaction Center of Rhodobacter Sphaeroides: In purple bacteria, the fundamental charge-separation step that drives the\nconversion of radiation energy into chemical energy proceeds along one branch -\nthe A branch - of a heterodimeric pigment-protein complex, the reaction center.\nHere, we use first principles time-dependent density functional theory (TDDFT)\nwith an optimally-tuned range-separated hybrid functional to investigate the\nelectronic and excited-state structure of the primary six pigments in the\nreaction center of \\textit{Rhodobacter sphaeroides}. By explicitly including\namino-acid residues surrounding these six pigments in our TDDFT calculations,\nwe systematically study the effect of the protein environment on energy and\ncharge-transfer excitations. Our calculations show that a forward charge\ntransfer into the A branch is significantly lower in energy than the first\ncharge transfer into the B branch, in agreement with the unidirectional charge\ntransfer observed experimentally. We further show that inclusion of the protein\nenvironment redshifts this excitation significantly, allowing for energy\ntransfer from the coupled $Q_x$ excitations. Through analysis of transition and\ndifference densities, we demonstrate that most of the $Q$-band excitations are\nstrongly delocalized over several pigments and that both their spatial\ndelocalization and charge-transfer character determine how strongly affected\nthey are by thermally-activated molecular vibrations. Our results suggest a\nmechanism for charge-transfer in this bacterial reaction center and pave the\nway for further first-principles investigations of the interplay between\ndelocalized excited states, vibronic coupling, and the role of the protein\nenvironment of this and other complex light-harvesting systems."
    },
    {
        "anchor": "Shape Selection and Multi-stability in Helical Ribbons: Helical structures, almost ubiquitous in biological systems, have inspired\nthe design and manufacturing of helical devices with applications in\nnanoelecromechanical systems (NEMS), morphing structures, optoelectronics,\nmicro-robotics and drug delivery devices. Meanwhile, multi-stable structures,\nrepresented by the Venus flytrap and slap bracelet, have attracted increasing\nattention due to their applications in making artificial muscles, bio-inspired\nrobots, deployable aerospace components and energy harvesting devices. Here we\nshow that the mechanical anisotropy pertinent to helical deformation, together\nwith geometric nonlinearity associated with multi-stability, can lead to novel\nselection principle of the geometric shape and multi-stability in spontaneous\nhelical ribbons. Simple table-top experiments were also performed to illustrate\nthe working principle. Our work will promote understanding of spontaneous\ncurling, twisting, wrinkling of thin objects and their instabilities, and serve\nas a tool in developing functional structures and devices with tunable,\nmorphing geometries and smart actuation mechanism that can be applied in a\nspectrum of areas.",
        "positive": "Wave control through soft microstructural curling: bandgap shifting,\n  reconfigurable anisotropy and switchable chirality: In this work, we discuss and numerically validate a strategy to attain\nreversible macroscopic changes in the wave propagation characteristics of\ncellular metamaterials with soft microstructures. The proposed cellular\narchitecture is characterized by unit cells featuring auxiliary populations of\nsymmetrically-distributed smart cantilevers stemming from the nodal locations.\nThrough an external stimulus (the application of an electric field), we induce\nextreme, localized, reversible curling deformation of the cantilevers---a shape\nmodification which does not affect the overall shape, stiffness and load\nbearing capability of the structure. By carefully engineering the spatial\npattern of straight (non activated) and curled (activated) cantilevers, we can\ninduce several profound modifications of the phononic characteristics of the\nstructure: generation and/or shifting of total and partial bandgaps, cell\nsymmetry relaxation (which implies reconfigurable wave beaming), and chirality\nswitching. While in this work we discuss the specific case of composite\ncantilevers with a PDMS core and active layers of electrostrictive terpolymer\nP(VDF-TrFE-CTFE), the strategy can be extended to other smart materials (such\nas dielectric elastomers or shape-memory polymers)."
    },
    {
        "anchor": "Memory in nonmonotonic stress relaxation of a granular system: We demonstrate experimentally that a granular packing of glass spheres is\ncapable of storing memory of multiple strain states in the dynamic process of\nstress relaxation. Modeling the system as a non-interacting population of\nrelaxing elements, we find that the functional form of the predicted relaxation\nrequires a quantitative correction which grows in severity with each additional\nmemory and is suggestive of interactions between elements. Our findings have\nimplications for the broad class of soft matter systems that display memory and\nanomalous relaxation.",
        "positive": "The Yield-Strain in Shear Banding Amorphous Solids: In recent research it was found that the fundamental shear-localizing\ninstability of amorphous solids under external strain, which eventually results\nin a shear band and failure, consists of a highly correlated array of Eshelby\nquadrupoles all having the same orientation and some density $\\rho$. In this\npaper we calculate analytically the energy $E(\\rho,\\gamma)$ associated with\nsuch highly correlated structures as a function of the density $\\rho$ and the\nexternal strain $\\gamma$. We show that for strains smaller than a\ncharacteristic strain $\\gamma_Y$ the total strain energy initially increases as\nthe quadrupole density increases, but that for strains larger than $\\gamma_Y$\nthe energy monotonically decreases with quadrupole density. We identify\n$\\gamma_Y$ as the yield strain. Its value, derived from values of the qudrupole\nstrength based on the atomistic model, agrees with that from the computed\nstress-strain curves and broadly with experimental results."
    },
    {
        "anchor": "From Molecular Dynamics to hydrodynamics - a novel Galilean invariant\n  thermostat: This article proposes a novel thermostat applicable to any particle-based\ndynamic simulation. Each pair of particles is thermostated either (with\nprobability P) with a pairwise Lowe-Andersen thermostat, or (with probability\n1-P) with a thermostat that is introduced here, which is based on a pairwise\ninteraction similar to the Nose-Hoover thermostat. When the pairwise\nNose-Hoover thermostat dominates (low P), the liquid has a high diffusion\ncoefficient and low viscosity, but when the Lowe-Andersen thermostat dominates,\nthe diffusion coefficient is low and viscosity is high. This novel\nNose-Hoover-Lowe-Andersen thermostat is Galilean invariant and preserves both\ntotal linear and angular momentum of the system, due to the fact that the\nthermostatic forces between each pair of the particles are pairwise additive\nand central. We show by simulation that this thermostat also preserves\nhydrodynamics. For the (non-interacting) ideal gas at P=0, the diffusion\ncoefficient diverges and viscosity is zero, while for P>0 it has a finite\nvalue. By adjusting probability P, the Schmidt number can be varied by orders\nof magnitude. The temperature deviation from the required value is at least an\norder of magnitude smaller than in Dissipative Particle Dynamics (DPD), while\nthe equilibrium properties of the system are very well reproduced. Applications\nof this thermostat include all standard molecular dynamic simulations of dense\nliquids and solids with any type of force field, as well as hydrodynamic\nsimulation of multi-phase systems with largely different bulk viscosities,\nincluding surface viscosity, and of dilute gases and plasmas.",
        "positive": "Role of disorder in determining the vibrational properties of\n  mass-spring networks: By introducing four fundamental types of disorders into a two-dimensional\ntriangular lattice separately, we determine the role of each type of disorder\nin the vibration of the resulting mass-spring networks. We are concerned mainly\nwith the origin of the boson peak and the connection between the boson peak and\nthe transverse Ioffe-Regel limit. For all types of disorders, we observe the\nemergence of the boson peak and Ioffe-Regel limits. With increasing disorder,\nthe boson peak frequency $\\omega_{BP}$, transverse Ioffe-Regel frequency\n$\\omega_{IR}^T$, and longitudinal Ioffe-Regel frequency $\\omega_{IR}^L$ all\ndecrease. We find that there are two ways for the boson peak to form:\ndeveloping from and coexisting with (but remaining independent of) the\ntransverse van Hove singularity without and with local coordination number\nfluctuation. In the presence of a single type of disorder, $\\omega_{IR}^T\\ge\n\\omega_{BP}$, and $\\omega_{IR}^T\\approx \\omega_{BP}$ only when the disorder is\nsufficiently strong and causes spatial fluctuation of the local coordination\nnumber. Moreover, if there is no positional disorder, $\\omega_{IR}^T\\approx\n\\omega_{IR}^L$. Therefore, the argument that the boson peak is equivalent to\nthe transverse Ioffe-Regel limit is not general. Our results suggest that both\nlocal coordination number and positional disorder are necessary for the\nargument to hold, which is actually the case for most disordered solids such as\nmarginally jammed solids and structural glasses. We further combine two types\nof disorders to cause disorder in both the local coordination number and\nlattice site position. The density of vibrational states of the resulting\nnetworks resembles that of marginally jammed solids well. However, the relation\nbetween the boson peak and the transverse Ioffe-Regel limit is still indefinite\nand condition-dependent."
    },
    {
        "anchor": "Glass transition of an epoxy resin induced by temperature, pressure and\n  chemical conversion: a configurational entropy rationale: A comparative study is reported on the dynamics of a glass-forming epoxy\nresin when the glass transition is approached through different paths: cooling,\ncompression, and polymerization. In particular, the influence of temperature,\npressure and chemical conversion on the dynamics has been investigated by\ndielectric spectroscopy. Deep similarities are found in dynamic properties. A\nunified reading of our experimental results for the structural relaxation time\nis given in the framework of the Adam-Gibbs theory. The quantitative agreement\nwith the experimental data is remarkable, joined with physical values of the\nfitting parameters. In particular, the fitting function of the isothermal\ntau(P) data gives a well reasonable prediction for the molar thermal expansion\nof the neat system, and the fitting function of the isobaric-isothermal tau(C)\ndata under step- polymerization conforms to the prediction of diverging tau at\ncomplete conversion of the system.",
        "positive": "Contact Angle of an Evaporating Droplet of Binary Solution on a Super\n  Wetting Surface: We study the dynamics of contact angle of a droplet of binary solution\nevaporating on a super wetting surface. Recent experiments show that although\nequilibrium contact angle of such droplet is zero, the contract angle can show\ncomplex time dependence before reaching the equilibrium value. We analyse such\nphenomena by extending our previous theory for the dynamics of an evaporating\nsingle component droplet to double component droplet. We show that the time\ndependence of the contact angle can be quite complex. Typically, it first\ndecreases slightly, and then increases and finally decreases again. Under\ncertain conditions, we find that the contact angle remains constant over a\ncertain period of time during evaporation. We study how the plateau or peak\ncontact angle depends on the initial composition and the humidity. The theory\nexplains experimental results reported previously."
    },
    {
        "anchor": "Linear models for thin plates of polymer gels: Within the linearized three-dimensional theory of polymer gels, we consider a\nsequence of problems formulated on a family of cylindrical domains whose height\ntends to zero. We assume that the fluid pressure is controlled at the top and\nbottom faces of the cylinder, and we consider two different scaling regimes for\nthe diffusivity tensor. Through asymptotic-analysis techniques we obtain two\nplate models where the transverse displacement is governed by a plate equation\nwith an extra contribution from the fluid pressure. In the limit obtained\nwithin the first scaling regime the fluid pressure is affine across the\nthickness and hence it is determined by its instantaneous trace on the top and\nbottom faces. In the second model, instead, the value of the fluid pressure is\ngoverned by a three-dimensional diffusion equation.",
        "positive": "A non-traditional view on the modeling of nematic disclination dynamics: Nonsingular disclination dynamics in a uniaxial nematic liquid crystal is\nmodeled within a mathematical framework where the kinematics is a direct\nextension of the classical way of identifying these line defects with\nsingularities of a unit vector field representing the nematic director. It is\nwell known that the universally accepted Oseen-Frank energy is infinite for\nconfigurations that contain disclination line defects. We devise a natural\naugmentation of the Oseen-Frank energy to account for physical situations\nwhere, under certain conditions, infinite director gradients have zero\nassociated energy cost, as would be necessary for modeling half-integer\nstrength disclinations within the framework of the director theory. Equilibria\nand dynamics (in the absence of flow) of line defects are studied within the\nproposed model. Using appropriate initial/boundary data, the gradient-flow\ndynamics of this energy leads to non-singular, line defect equilibrium\nsolutions, including those of half-integer strength. However, we demonstrate\nthat the gradient flow dynamics for this energy is not able to adequately\ndescribe defect evolution. Motivated by similarity with dislocation dynamics in\nsolids, a novel 2D-model of disclination dynamics in nematics is proposed. The\nmodel is based on the extended Oseen-Frank energy and takes into account\nthermodynamics and the kinematics of conservation of defect topological charge.\nWe validate this model through computations of disclination equilibria,\nannihilation, repulsion, and splitting. We show that the energy function we\ndevise, suitably interpreted, can serve as well for the modeling of equilibria\nand dynamics of dislocation line defects in solids making the conclusions of\nthis paper relevant to mechanics of both solids and liquid crystals."
    },
    {
        "anchor": "Spin glass transitions of smectic-$A$ crosslinked elastomers: Elastomers are artificial polymeric materials created for industrial and\ncommercial applications. Depending on their purpose, they are performing in\ndifferent species and structure modifications. Our studies focus on the systems\nof elastomers randomly standing-distributed in a smectic $A$ (Sm$A$) liquid\ncrystal. Basing on the suggestion following from the experiment, that at a\nphase transition from Sm$A$ to nematic phase caused by an increase of a\ncrosslink concentration, such a system survives a percolation transition at low\ncrossilink concentrations, we propose a modeling explaining this phenomena. We\napprove the three-dimensional Villain spin glass model and apply lattice Monte\nCarlo (MC) techniques on differential forms on a dual lattice, that is an\nalternative of a replica trick, developed for nematic elastomers in the 3D XY\nuniversality. In the results of that we have confirmed a concentration phase\ntransition of percolation nature at a small crosslink concentration ($\\sim$ 10\nweight %).",
        "positive": "Adhesion of microcapsules: The adhesion of microcapsules to an attractive contact potential is studied\ntheoretically. The axisymmetric shape equations are solved numerically. Beyond\na universal threshold strength of the potential, the contact radius increases\nlike a square root of the strength. Scaling functions for the corresponding\namplitudes are derived as a function of the elastic parameters."
    },
    {
        "anchor": "Liquid Surface X-ray Studies of Gold Nanoparticle-Phospholipid Films at\n  the Air/Water Interface: Amphiphilic phospholipids and nanoparticles functionalized with hydrophobic\ncapping ligands have previously been extensively investigated for their\ncapacity to self-assemble into Langmuir monolayers at the air/water interface.\nHowever, understanding of composite films consisting of both nanoparticles and\nphospholipids, and by extension, the complex interactions arising between\nnanomaterials and biological membranes, remains limited. In this work,\ndodecanethiol-capped gold nanoparticles (Au-NPs) with an average core diameter\nof 6 nm were incorporated into 1,2-dipalmitoyl-sn-glycero-3-phosphocholine\n(DPPC) monolayers in area ratios ranging from 0.1 to 20% area coverage at a\nsurface pressure of 30 mN/m. High resolution liquid surface X-ray scattering\nstudies revealed a phase separation of the DPPC and Au-NP components of the\ncomposite film, as confirmed with atomic force microscopy after the film was\ntransferred to a substrate. At low Au-NP content, the structural organization\nof the phase-separated film is best described as a DPPC film containing\nisolated islands of Au-NPs. However, increasing the Au-NP content beyond 5%\narea coverage transforms the structural organization of the composite film to a\nlong-range interconnected network of Au-NP strands surrounding small seas of\nDPPC, where the density of the Au-NP network increases with increasing Au-NP\ncontent. The observed phase separation and structural organization of the\nphospholipid and nanoparticle components in these Langmuir monolayers are\nuseful for understanding interactions of nanoparticles with biological\nmembranes.",
        "positive": "Curvature Elasticity of the Electric Double Layer: Mean-field electrostatics is used to calculate the bending moduli of an\nelectric double layer for fixed surface charge density of a macroion in a\nsymmetric 1:1 electrolyte. The resulting expressions for bending stiffness,\nGaussian modulus, and spontaneous curvature refer to a general underlying\nequation of state of the electrolyte, subject to a local density approximation\nand the absence of dipole and higher-order fields. We present results for\nselected applications: the lattice-gas Poisson-Fermi model with and without\nasymmetric ion sizes, and the Poisson-Carnahan-Starling model."
    },
    {
        "anchor": "Deformation profiles and microscopic dynamics of complex fluids during\n  oscillatory shear experiments: Oscillatory shear tests are widely used in rheology to characterize the\nlinear and non-linear mechanical response of complex fluids, including the\nyielding transition. There is an increasing urge to acquire detailed knowledge\nof the deformation field that is effectively present across the sample during\nthese tests; at the same time, there is mounting evidence that the macroscopic\nrheological response depends on the elusive microscopic behavior of the\nmaterial constituents. Here we employ a strain-controlled shear-cell with\ntransparent walls to visualize and quantify the dynamics of tracers embedded in\nvarious cyclically sheared complex fluids, ranging from almost-ideal elastic to\nyield stress fluids. For each sample, we use image correlation processing to\nmeasure the macroscopic deformation field, and echo-Differential Dynamic\nMicroscopy to probe the microscopic irreversible sample dynamics in reciprocal\nspace; finally, we devise a simple scheme to spatially map the rearrangements\nin the sheared sample, once again without tracking the tracers. For the yield\nstress sample, we obtain a wave-vector dependent characterization of\nshear-induced diffusion across the yielding transition, which is accompanied by\na three-order-of-magnitude speed-up of the dynamics and by a transition from\nlocalized, intermittent rearrangements to a more spatially homogeneous and\ntemporally uniform activity. Our tracking free approach is intrinsically\nmulti-scale, can successfully discriminate between different types of dynamics,\nand can be automated to minimize user intervention. Applications are many, as\nit can be translated to other imaging modes, including fluorescence, and can be\nused with sub-resolution tracers and even without tracers, for samples that\nprovide intrinsic optical contrast.",
        "positive": "Fluctuation modes of a twist-bend nematic liquid crystal: We report a dynamic light scattering study of the fluctuation modes in a\nthermotropic liquid crystalline mixture of monomer and dimer compounds that\nexhibits the twist-bend nematic ($\\mathrm{N_{TB}}$) phase. The results reveal a\nspectrum of overdamped fluctuations that includes two nonhydrodynamic and one\nhydrodynamic mode in the $\\mathrm{N_{TB}}$ phase, and a single nonhydrodynamic\nplus two hydrodynamic modes (the usual nematic optic axis or director\nfluctuations) in the higher temperature, uniaxial nematic phase. The properties\nof these fluctuations and the conditions for their observation are\ncomprehensively explained by a Landau-deGennes expansion of the free energy\ndensity in terms of heliconical director and helical polarization fields that\ncharacterize the $\\mathrm{N_{TB}}$ structure, with the latter serving as the\nprimary order parameter. A \"coarse-graining\" approximation simplifies the\ntheoretical analysis, and enables us to demonstrate quantitative agreement\nbetween the calculated and experimentally determined temperature dependence of\nthe mode relaxation rates."
    },
    {
        "anchor": "Control of superselectivity by crowding in three-dimensional hosts: Motivated by the fine compositional control observed in membraneless droplet\norganelles in cells, we investigate how a sharp binding-unbinding transition\ncan occur between multivalent client molecules and receptors embedded in a\nporous three-dimensional structure. In contrast to similar superselective\nbinding previously observed at surfaces, we have identified that a key effect\nin a three-dimensional environment is that the presence of inert crowding\nagents can significantly enhance or even introduce superselectivity. In\nessence, molecular crowding initially suppresses binding via an entropic\npenalty, but the clients can then more easily form many bonds simultaneously.\nWe demonstrate the robustness of the superselective behavior with respect to\nclient valency, linker length and binding interactions in Monte Carlo\nsimulations of an archetypal lattice polymer model.",
        "positive": "Lateral response of a layered material with interlayer friction: We investigate the mechanical properties of a layered material with\ninterlayer friction. We propose a model that contains lateral elasticity and\ninterlayer friction to obtain the response function both in the Fourier and\nreal spaces. By investigating how the internal deformation is laterally induced\ndue to the applied surface displacement, we find that it is transmitted into\nthe material with an apparent phase difference. We also obtain the effective\ncomplex modulus of the layered material and show that it exhibits an\nintermediate power-law behavior in the low-frequency regime. Our result can be\nused to estimate the internal deformation of layered materials that exist on\nvarious different scales."
    },
    {
        "anchor": "The yielding transition in periodically sheared binary glasses at finite\n  temperature: Non-equilibrium molecular dynamics simulations are performed to investigate\nthe dynamic behavior of three-dimensional binary glasses prepared via an\ninstantaneous quench across the glass transition. We found that with increasing\nstrain amplitude up to a critical value, the potential energy approaches lower\nminima in steady state, whereas the amplitude of shear stress oscillations\nbecomes larger. Below the yielding transition, the storage modulus dominates\nthe mechanical response, and the gradual decay of the potential energy over\nconsecutive cycles is accompanied by reduction in size of transient clusters of\natoms with large nonaffine displacements. In contrast, above the yield strain,\nthe loss modulus increases and the system settles at a higher level of\npotential energy due to formation of a system-spanning shear band after a\nnumber of transient cycles.",
        "positive": "Predictive local field theory for interacting active Brownian spheres in\n  two spatial dimensions: We present a predictive local field theory for the nonequilibrium dynamics of\ninteracting active Brownian particles with a spherical shape in two spatial\ndimensions. The theory is derived by a rigorous coarse-graining starting from\nthe Langevin equations that describe the trajectories of the individual\nparticles. For maximal accuracy and generality of the theory, it includes\nconfigurational order parameters and derivatives up to infinite order. In\naddition, we discuss possible approximations of the theory and present reduced\nmodels that are easier to apply. We show that our theory contains popular\nmodels such as Active Model B + as special cases and that it provides explicit\nexpressions for the coefficients occurring in these and other, often\nphenomenological, models. As a further outcome, the theory yields an analytical\nexpression for the density-dependent mean swimming speed of the particles. To\ndemonstrate an application of the new theory, we analyze a simple reduced model\nof the lowest nontrivial order in derivatives, which is able to predict the\nonset of motility-induced phase separation of the particles. By a linear\nstability analysis, an analytical expression for the spinodal corresponding to\nmotility-induced phase separation is obtained. This expression is evaluated for\nthe case of particles interacting repulsively by a Weeks-Chandler-Anderson\npotential. The analytical predictions for the spinodal associated with these\nparticles are found to be in very good agreement with the results of Brownian\ndynamics simulations that are based on the same Langevin equations as our\ntheory. Furthermore, the critical point predicted by our analytical results\nagrees excellently with recent computational results from the literature."
    },
    {
        "anchor": "Shear-induced migration in colloidal suspensions: Using Brownian dynamics simulations we perform a systematic investigation of\nthe shear-induced migration of colloidal particles subject to Poiseuille flow\nin both cylindrical and planar geometry. We find that adding an attractive\ncomponent to the interparticle interaction enhances the migration effect,\nconsistent with recent simulation studies of platelet suspensions.\nMonodisperse, bidisperse and polydisperse systems are studied over a range of\nshear rates, considering both steady states and the transient dynamics arising\nfrom the onset of flow. For bidisperse and polydisperse systems size\nsegregation is observed.",
        "positive": "Elastic Barriers and Formation of Nanoscale Switching Networks: Thin films of silicon oxide (SiOx) are mixtures of semiconductive c-Si\nnanoclusters (NC) embedded in an insulating g-SiO2 matrix. Tour et al. have\nshown that a trenched thin film geometry enables the NC to form semiconductive\nfilamentary arrays when driven by an applied field. The field required to form\nreversible nanoscale switching networks (NSN) decreases rapidly within a few\ncycles, or by annealing at 600 C in even fewer cycles, and is stable to 700C.\nHere we discuss an elastic mechanism that explains why a vertical edge across\nthe planar Si-SiOx interface is necessary to form NSN. The discussion shows\nthat the formation mechanism is intrinsic and need not occur locally at the\nedge, but can occur anywhere in the SiOx film, given the unpinned nanoscale\nvertical edge geometry."
    },
    {
        "anchor": "Controlling the rheo-electric properties of graphite/carbon black\n  suspensions by 'flow-switching': The ability to manipulate rheological and electrical properties of colloidal\ncarbon black gels makes them attractive in composites for energy applications\nsuch as batteries and fuel cells, where they conduct electricity and prevent\nsedimentation of `granular' active components. While it is commonly assumed\nthat granular fillers have a simple additive effect on the composite\nproperties, new phenomena can emerge unexpectedly, with some composites\nexhibiting a unique rheological bi-stability between solid-like and liquid-like\nstates. Here we report such bi-stability in suspensions of non-Brownian\ngraphite and colloidal carbon black in oil, a model system to mimic composite\nsuspensions for energy applications. Steady shear below a critical stress\nelicits a transition to a persistent mechanically weak and poorly conducting\nstate, which must be `rejuvenated' using high-stress shear to recover a\nstronger, high-conductivity state. Our findings highlight the highly tunable\nnature of binary granular/gel composite suspensions, and present new\npossibilities for optimizing mixing and processing conditions for Li-ion\nbattery slurries.",
        "positive": "Multisector method for arteries: The residual stresses of\n  circumferential rings with non-trivial openings: The opening angle method is a most popular choice in biomechanics to estimate\nresidual stresses in arteries. Experimentally, it means that an artery is cut\ninto rings; then the rings are cut axially: they open up into sectors; and the\ncorresponding opening angles are measured to give residual stress levels by\nsolving an inverse problem. However, in the lab, for many tissues--more\ncommonly in pathological tissues, the ring does not open according to the\ntheory, into a neat single circular sector, but rather creates an asymmetric\ngeometry, often with abruptly changing curvature(s). This phenomenon might be\ndue to a number of reasons including variation in thickness, microstructure,\nvarying mechanical properties, etc. As a result, these samples have to be\neliminated from studies relying on the opening angle method, which limits\nprogress in understanding and evaluating residual stresses in all real\narteries. With this work we propose an effective approach to deal with these\nnon-trivial openings of rings. First we digitalise pictures of opened rings to\nsplit them into multiple, connected circular sectors. Then we measure the\ncorresponding opening angles for each sub-sector. Finally we can determine the\nnon-homogeneous distribution of residual stresses for individual sectors in a\nclosed ring configuration."
    },
    {
        "anchor": "Metastable elastocapillary systems with negative compressibility: Although coveted in applications, few materials expand when subject to\ncompression or contract under decompression, i.e., exhibit negative\ncompressibility transition. A key step to achieve such counterintuitive\nbehaviour is the destabilizations of (meta)stable equilibria of the\nconstituents. Here, we propose a simple strategy to obtain negative\ncompressibility exploiting capillary forces both to precompress the elastic\nmaterial and to release such precompression by a threshold phenomenon -- the\nreversible intrusion of a liquid into a lyophobic flexible cavity. The\nmetastable elastocapillary system we designed according to these principles\nachieved the largest mechanical negative compressibility ever reported.\nExperiments demonstrate that the concept is effective all the way from\nhydrophobic subnanometre porous materials to millimetre-sized metamaterials and\nis relevant for diverse fields, including materials science and biology,\nproviding a simple, cross-scale, and flexible platform to endow materials with\nnegative compressibility for technological and biomedical applications.",
        "positive": "The Life of a Surface Bubble: Surface bubbles are present in many industrial processes and in nature, as\nwell as in CO$_2$ beverage. They have motivated many theoretical, numerical and\nexperimental works. This paper presents the current knowledge on the physics of\nsurface bubbles lifetime and shows the diversity of mechanisms at play that\ndepend on the properties of the bath, the interfaces and the ambient air.\n  In particular, we explore the role of drainage and evaporation on film\nthinning.\n  We highlight the existence of two different scenarios depending on whether\nthe film cap ruptures at large or small thickness compared to the thickness at\nwhich van der Waals interaction come in to play."
    },
    {
        "anchor": "Jeffery Orbits with Noise Revisited: The behavior of non-spherical particles in a shear-flow is of significant\npractical and theoretical interest. These systems have been the object of\nnumerous investigations since the pioneering work of Jeffery a century ago. His\neponymous orbits describe the deterministic motion of an isolated, rod-like\nparticle in a shear flow. Subsequently, the effect of adding noise was\ninvestigated. The theory has been applied to colloidal particles,\nmacromolecules, anisometric granular particles and most recently to\nmicroswimmers, for example bacteria. We study the Jeffery orbits of elongated\nparticles subject to noise using Langevin simulations and a Fokker-Planck\nequation. We extend the analytical solution for infinitely thin needles\n($\\beta=1$) obtained by Doi and Edwards to particles with arbitrary shape\nfactor ($0\\le \\beta\\le 1$) and validate the theory by comparing it with\nsimulations. We examine the rotation of the particle around the vorticity axis\nand study the orientational order matrix. We use the latter to obtain scalar\norder parameters $s$ and $r$ describing nematic ordering and biaxiality from\nthe orientational distribution function. The value of $s$ (nematic ordering)\nincreases monotonically with increasing P\\'eclet number, while $r$ (measure of\nbiaxiality) displays a maximum value. From perturbation theory we obtain simple\nexpressions that provide accurate descriptions at low noise (or large P\\'eclet\nnumbers). We also examine the orientational distribution in the v-grad v plane\nand in the perpendicular direction. Finally we present the solution of the\nFokker-Planck equation for a strictly two-dimensional (2D) system. For the same\nnoise amplitude the average rotation speed of the particle in 3D is larger than\nin 2D.",
        "positive": "Stability of a tilted granular monolayer: How many spheres can we pick\n  before the collapse?: The triggering of avalanches is investigated using discrete element\nsimulations for a process of random extraction of spheres. A monolayer, formed\nby identical spheres in a hexagonal configuration, is placed on a tilted plane\nsurrounded by a small fence that sustains the spheres, mimicking the disposal\nof fruits in the market. Then, a random continuous extraction process of\nspheres is imposed until the collapse. For this simple numerical experiment, a\nphase diagram was obtained to visualize the occurrence of avalanches triggered\nby vacancies as a function of the tilting angle, system size, and friction\ncoefficient. More importantly, a sub-zone was found where we can predict the\ncritical number of extractions until the avalanche takes place. The prediction\nis made from an evolution model of the average coordination number based on\nstatistical considerations. The theoretical prediction also gives a constant\ncritical void fraction of spheres, which implies the system collapses at a\ncritical packing fraction."
    },
    {
        "anchor": "Micelle formation, gelation and phase separation of amphiphilic\n  multiblock copolymers: The phase behaviour of amphiphilic multiblock copolymers with a large number\nof blocks in semidilute solutions is studied by lattice Monte Carlo\nsimulations. The influence on the resulting structures of the concentration,\nthe solvent quality and the ratio of hydrophobic to hydrophilic monomers in the\nchains has been assessed explicitely. Several distinct regimes are put in\nevidence. For poorly substituted (mainly hydrophilic) copolymers formation of\nmicelles is observed, either isolated or connected by the hydrophilic moieties,\ndepending on concentration and chain length. For more highly substituted chains\nlarger tubular hydrophobic structures appear which, at higher concentration,\njoin to form extended hydrophobic cores. For both substitution ratios gelation\nis observed, but with a very different gel network structure. For the poorly\nsubstituted chains the gel consists of micelles cross-linked by hydrophilic\nblocks whereas for the highly substituted copolymers the extended hydrophobic\ncores form the gelling network. The interplay between gelation and phase\nseparation clearly appears in the phase diagram. In particular, for poorly\nsubstituted copolymers and in a narrow concentration range, we observe a\nsol-gel transition followed by an inverse gel-sol transition when increasing\nthe interaction energy. The simulation results are discussed in the context of\nthe experimentally observed phase properties of methylcellulose, a\nhydrophobically substituted polysaccharide.",
        "positive": "Non-orientable order and non-Abelian response in frustrated\n  metamaterials: From atomic crystals to bird flocks, most forms of order are captured by the\nconcept of spontaneous symmetry breaking. This paradigm was challenged by the\ndiscovery of topological order, in materials where the number of accessible\nstates is not solely determined by the number of broken symmetries, but also by\nspace topology. Until now however, the concept of topological order has been\nlinked to quantum entanglement and has therefore remained out of reach in\nclassical systems. Here, we show that classical systems whose global geometry\nfrustrates the emergence of homogeneous order realise an unanticipated form of\ntopological order defined by non-orientable order-parameter bundles:\nnon-orientable order. We validate experimentally and theoretically this concept\nby designing frustrated mechanical metamaterials that spontaneously break a\ndiscrete symmetry under homogeneous load. While conventional order leads to a\ndiscrete ground-state degeneracy, we show that non-orientable order implies an\nextensive ground-state degeneracy -- in the form of topologically protected\nzero-nodes and zero-lines. Our metamaterials escape the traditional\nclassification of order by symmetry breaking. Considering more general stress\ndistributions, we leverage non-orientable order to engineer robust mechanical\nmemory and achieve non-Abelian mechanical responses that carry an imprint of\nthe braiding of local loads. We envision this principle to open the way to\ndesigner materials that can robustly process information across multiple areas\nof physics, from mechanics to photonics and magnetism."
    },
    {
        "anchor": "Exploiting classical nucleation theory for reverse self-assembly: In this paper we introduce a new method to design interparticle interactions\nto target arbitrary crystal structures via the process of self-assembly. We\nshow that it is possible to exploit the curvature of the crystal nucleation\nfree-energy barrier to sample and select optimal interparticle interactions for\nself-assembly into a desired structure. We apply this method to find\ninteractions to target two simple crystal structures: a crystal with simple\ncubic symmetry and a two-dimensional plane with square symmetry embedded in a\nthree-dimensional space. Finally, we discuss the potential and limits of our\nmethod and propose a general model by which a functionally infinite number of\ndifferent interaction geometries may be constructed and to which our reverse\nself-assembly method could in principle be applied.",
        "positive": "A water-like model under confinement for hydrophobic and hydrophilic\n  particle-plate interaction potentials: Molecular dynamic simulations were employed to study a water-like model\nconfined between hydrophobic and hydrophilic plates. The phase behavior of this\nsystem is obtained for different distances between the plates and\nparticle-plate potentials. For both hydrophobic and hydrophilic walls there are\nthe formation of layers. Crystallization occurs at lower temperature at the\ncontact layer than at the middle layer. In addition, the melting temperature\ndecreases as the plates become more hydrophobic. Similarly, the temperatures of\nmaximum density and extremum diffusivity decrease with hydrophobicity."
    },
    {
        "anchor": "The mechanism of secondary structural changes in Keratinocyte Growth\n  Factor during uptake and release from a hydroxyethyl(methacrylate) hydrogel\n  revealed by 2D Correlation Spectroscopy: Incomplete release profiles of protein delivery systems can be caused by\nunfolding and denaturation of proteins due to protein-biomaterial interactions.\nThis paper investigates the mechanisms causing incomplete release of the wound\nhealing protein, Keratinocyte Growth Factor (KGF), from a\nhydroxyethyl(methacrylate) (HEMA) hydrogel by FTIR-ATR spectroscopy and 2D\ncorrelation spectroscopy. This work characterizes KGF secondary structure\nreflected in the amide I region of the FTIR-ATR spectrum, and differences\nbetween active and heat denatured KGF. These results have been used to\ninvestigate the sequence of time-dependent changes in KGF at the surface of the\nHEMA hydrogel during uptake and release by 2D correlation spectroscopy. KGF\nstays active throughout the uptake process, and the KGF loop structures\ninteract with HEMA moieties, potentially mimicking receptor-ligand\ninteractions. KGF denatures during release via changes in the loops and\nunfolding of the extended strands. Our results suggest that a high affinity\ninteraction between the HEMA hydrogel and KGF is beneficial for efficient\nloading of KGF into the hydrogel, but is too strong and prevents complete KGF\nrelease due to unfolding and denaturation of KGF. This work informs future\nmaterial design that will target different secondary structural elements of KGF\nin order to preserve its native conformation and allow for complete release.",
        "positive": "Collective Dynamics of Deformable Self-Propelled Particles with\n  Repulsive Interaction: We investigate dynamics of deformable self-propelled particles with a\nrepulsive interaction whose magnitude depends on the relative direction of\nelongation of a pair of particles. A collective motion of the particles appears\nin two dimensions. However this ordered state becomes unstable when the\nparticle density exceeds a certain critical threshold and the dynamics becomes\ndisorder. We show by a mean field analysis that this novel transition\ncharacteristic to deformability occurs due to a saddle-node bifurcation."
    },
    {
        "anchor": "Disentangling the roles of roughness, friction and adhesion in\n  discontinuous shear thickening by means of thermo-responsive particles: Dense suspensions of colloidal or granular particles can display pronounced\nnon-Newtonian behaviour, such as discontinuous shear thickening (DST) and shear\njamming (SJ). The essential contribution of particle surface roughness and\nadhesive forces confirms that stress-activated contacts can play a key role in\nthese phenomena. By employing a system of microparticles coated by responsive\npolymers that allow friction, adhesion, and surface roughness to be selectively\nand independently tuned as a function of temperature, we offer a way to\ndisentangle these contributions. We find that DST occurs at lower shear rates\nwhen friction and adhesion between particles are enhanced at high temperatures.\nAdditionally, the temperature-responsive polymers provide lubricity at low\ntemperatures that can mask surface roughness. The link between single-particle\nproperties and macroscopic rheology is elucidated via lateral force microscopy,\nwhich reveals the nature of rheologically relevant contact conditions. In situ\ntemperature tuning during shear allows contact conditions to be modified, and\nDST to be switched on and off on demand. These findings strengthen our\nunderstanding of the microscopic parameters affecting DST and identify new\nroutes for the design of smart, non-Newtonian fluids.",
        "positive": "Wetting Transitions of Condensed Droplets on Superhydrophobic Surfaces\n  with Two-Tier Roughness: Although realizing wetting transitions of droplets spontaneously on solid\nrough surfaces is quite challenging, it is becoming a key research topic in\nmany practical applications which require highly efficient removal of liquid.\nWe report wetting transitions of condensed droplets occurring spontaneously on\npillared surfaces with two-tier roughness owing to excellent\nsuperhydrophobicity. The phenomenon results from further decreased Laplace\npressure on the top side of the individual droplet when its size becomes\ncomparable to the scale of the micropillars, which leads to a surprising robust\nspontaneous wetting transition, from valleys to tops of the pillars. A simple\nscaling law is derived theoretically, which demonstrates that the critical size\nof the droplet is determined by the space of the micropillars. For this reason,\nhighly efficient removal of water benefits greatly from smaller micropillar\nspace. Furthermore, three wetting transition modes exist, in which the in situ\nwetting behaviors are in good agreement with our quantitative theoretical\nanalysis."
    },
    {
        "anchor": "Shape Transitions in Hyperbolic Non-Euclidean Plates: We present and summarize the results of recent studies on non-Euclidean\nplates with imposed constant negative Gaussian curvature in both the F\\\"oppl -\nvon K\\'arm\\'an and Kirchhoff approximations. Motivated by experimental results\nwe focus on annuli with a periodic profile. We show that in the F\\\"oppl - von\nK\\'arm\\'an approximation there are only two types of global minimizers -- flat\nand saddle shaped deformations with localized regions of stretching near the\nboundary of the annulus. We also show that there exists local minimizers with\n$n$-waves that have regions of stretching near their lines of inflection. In\nthe Kirchhoff approximation we show that there exist exact isometric immersions\nwith periodic profiles. The number of waves in these configurations is set by\nthe condition that the bending energy remains finite and grows approximately\nexponentially with the radius of the annulus. For large radii, these shape are\nenergetically favorable over saddle shapes and could explain why wavy shapes\nare selected by crocheted models of the hyperbolic plane.",
        "positive": "Analysis of the shape of x-ray diffraction peaks originating from the\n  hexatic phase of liquid crystal films: X-ray diffraction studies of the bond-orientational order in the hexatic-B\nphase of 75OBC and 3(10)OBC compounds are presented. The temperature evolution\nof an angular profile of a single diffraction peak is analyzed. Close to the\nhexatic-B-smectic-A transition these profiles can be approximated by the\nGaussian function. At lower temperatures in the hexatic-B phase the profiles\nare better fitted by the Voigt function. Theoretical analysis of the width of\ndiffraction peaks in three-dimentional (3D) hexatics is performed on the basis\nof the effective Hamiltonian introduced by Aharony and Kardar. Theoretical\nestimations are in good agreement with the results of x-ray experiments."
    },
    {
        "anchor": "Asymmetries in triboelectric charging: generalizing mosaic models to\n  different-material samples and sliding contacts: Nominally identical materials exchange net electric charge during contact\nthrough a mechanism that is still debated. `Mosaic models', in which surfaces\nare presumed to consist of a random patchwork of microscopic donor/acceptor\nsites, offer an appealing explanation for this phenomenon. However, recent\nexperiments have shown that global differences persist even between\nsame-material samples, which the standard mosaic framework does not account\nfor. Here, we expand the mosaic framework by incorporating global differences\nin the densities of donor/acceptor sites. We develop an analytical model,\nbacked by numerical simulations, that smoothly connects the global and\ndeterministic charge transfer of different materials to the local and\nstochastic mosaic picture normally associated with identical materials. Going\nfurther, we extend our model to explain the effect of contact asymmetries\nduring sliding, providing a plausible explanation for reversal of charging sign\nthat has been observed experimentally.",
        "positive": "Conformational properties of active semiflexible polymers: The conformational properties of flexible and semiflexible polymers exposed\nto active noise are studied theoretically. The noise may originate from the\ninteraction of the polymer with surround- ing active (Brownian) particles or\nfrom the inherent motion of the polymer itself, which may be composed of active\nBrownian particles. In the latter case, the respective monomers are indepen-\ndently propelled in directions changing diffusively. For the description of the\npolymer, we adopt the continuous Gaussian semiflexible polymer model.\nSpecifically, the finite polymer extensibility is taken into account which\nturns out to be essentially for the polymer conformations. Our analytical\ncalculations predict a strong dependence of the relaxation times on the\nactivity. In particular, semi- flexible polymers exhibit a crossover from a\nbending-elasticity-dominated to the flexible-polymer dynamics with increasing\nactivity. This leads to a significant noise-induced polymer shrinkage over a\nlarge range of self-propulsion velocities. For large activities, the polymers\nswell and their extension becomes comparable to the contour length. The scaling\nproperties of the mean square end-to-end distance with respect to the polymer\nlength and monomer activity are discussed."
    },
    {
        "anchor": "Grabbing water: We introduce a novel technique for grabbing water with a flexible solid. This\nnew passive pipetting mechanism was inspired by floating flowers and relies\npurely on the coupling of the elasticity of thin plates and the hydrodynamic\nforces at the liquid interface. Developing a theoretical model has enabled us\nto design petal-shaped objects with maximum grabbing capacity.",
        "positive": "Posture Sway and the Transition Rate for a Fall: Postural body sway displacements for quiet standing subjects (measured with a\nnew ultrasonic device) are reported. Two of the well known strategies for\nbalancing, namely ankle and hip movements were probed. The data is modeled\nusing a Fokker-Plank-Langevin stochastic theory. Both analytic and computer\nsimulation techniques are employed. The Kramers transition rate for a fall is\nexpressed as a function of experimental parameters. The root mean square\nvelocity is especially important in determining the fall probability."
    },
    {
        "anchor": "The Physics of Drying of Colloidal Dispersion: Pattern Formation and\n  Desiccation Cracks: Drying of colloidal dispersion and their consolidation into a particulate\ndeposit is a common phenomenon. This process involves various physical\nprocesses such as diffusion of liquid molecules into the ambient atmosphere and\nadvection of dispersed particles via evaporation driven flow. The colloidal\nparticles forming a dried deposit exhibits distinct patterns and frequently\npossess structural defects such as desiccation cracks. This chapter gives an\nintroductory review of the drying of colloidal dispersion and various\nassociated phenomena. In principle, the drying of colloid dispersion, the\nprocess of their consolidation, and fluid-flow dynamics are all studied in\nnumerous drying configurations. Here we explain drying induced phenomena\nconcerning sessile drop drying. We begin with an introduction to colloids,\nprovide background on the physics of drying, and then explain the formation of\npattern and the desiccation cracks. The role of evaporation driven flows and\ntheir influence on particle accumulation, the impact of various physical\nparameters on pattern formation and cracks are all briefly illustrated.",
        "positive": "Behaviour of flexible superhydrophobic striped surfaces during\n  (electro-)wetting of a sessile drop: We study here the microscopic deformations of elastic lamellae constituting a\nsuperhydrophobic substrate under different wetting conditions of a sessile\ndroplet using electrowetting. The deformation profiles of the lamellae are\nexperimentally evaluated using confocal microscopy. These experimental results\nare then explained using a variational principle formalism within the framework\nof linear elasticity. We show that the local deformation profile of a lamella\nis mainly controlled by the net horizontal component of the capillary forces\nacting on its top due to the pinned droplet contact line. We also discuss the\nindirect role of electrowetting in dictating the deformation characteristics of\nthe elastic lamellae. One important conclusion is that the small deflection\nassumption, which is frequently used in the literature, fails to provide a\nquantitative description of the experimental results; a full solution of the\nnon-linear governing equation is necessary to describe the experimentally\nobtained deflection profiles."
    },
    {
        "anchor": "Peeling from a liquid: We establish the existence of a cusp in the curvature of a solid sheet at its\ncontact with a liquid subphase. We study two configurations in floating sheets\nwhere the solid-vapor-liquid contact line is a straight line and a circle,\nrespectively. In the former case, a rectangular sheet is lifted at its edge,\nwhereas in the latter a gas bubble is injected beneath a floating sheet. We\nshow that in both geometries the derivative of the sheet's curvature is\ndiscontinuous. We demonstrate that the boundary condition at the contact is\nidentical in these two geometries, even though the shape of the contact line\nand the stress distribution in the sheet are sharply different.",
        "positive": "Elastocapillary menisci mediate interaction of neighboring structures at\n  the surface of a compliant solid: Surface stress drives long-range elastocapillary interactions at the surface\nof compliant solids, where it has been observed to mediate interparticle\ninteractions and to alter the transport of liquid drops. We show that such an\nelastocapillary interaction arises between neighboring structures that are\nsimply protrusions of the compliant solid. For compliant micropillars arranged\nin a square lattice with spacing p less than an interaction distance p*, the\ndistance of a pillar to its neighbors determines how much it deforms due to\nsurface stress: pillars that are close together tend to be rounder and flatter\nthan those that are far apart. The interaction is mediated by the formation of\nan elastocapillary meniscus at the base of each pillar, which sets the\ninteraction distance and causes neighboring structures to deform more than\nthose that are relatively isolated. Neighboring pillars also displace toward\neach other to form clusters, leading to the emergence of pattern formation and\nordered domains."
    },
    {
        "anchor": "Transient birefringence of liquids induced by terahertz electric-field\n  torque on permanent molecular dipoles: Microscopic understanding of low-frequency molecular motions in liquids has\nbeen a longstanding goal in soft-matter science. So far, such low-frequency\nmotions have mostly been accessed indirectly by off-resonant optical pulses. A\nmore direct approach would be to interrogate the dynamic structure of liquids\nwith terahertz (THz) radiation. Here, we provide evidence that resonant\nexcitation with intense THz pulses is capable of driving\nreorientational-librational modes of aprotic polar liquids through coupling to\nthe permanent molecular dipole moments. We observe a hallmark of this enhanced\ncoupling: a transient optical birefringence up to an order of magnitude higher\nthan obtained with optical excitation. Our results open up the path to\napplications such as efficient molecular alignment and systematic study of the\ncoupling of rotational motion to other collective motions in liquids.",
        "positive": "Transforming from time to frequency without artefacts: I review a simple method, recently introduced to convert rheological\ncompliance measurements into frequency-dependent moduli. New experimental data\nare presented, and the scientific implications of various data conversion\nmethods discussed."
    },
    {
        "anchor": "Modelling of nematic liquid crystal display devices: A lattice Boltzmann scheme is presented which recovers the dynamics of\nnematic and chiral liquid crystals; the method essentially gives solutions to\nthe Qian-Sheng equations for the evolution of the velocity and tensor\norder-parameter fields. The resulting algorithm is able to include five\nindependent Leslie viscosities, a Landau-deGennes free energy which introduces\nthree or more elastic constants, a temperature dependent order parameter,\nsurface anchoring and viscosity coefficients, flexo-electric and order\nelectricity and chirality. When combined with a solver for the Maxwell\nequations associated with the electric field, the algorithm is able to provide\na full 'device solver' for a liquid crystal display. Coupled lattice Boltzmann\nschemes are used to capture the evolution of the fast momentum and slow\ndirector motions in a computationally efficient way. The method is shown to\ngive results in close agreement with analytical results for a number of\nvalidating examples. The use of the method is illustrated through the\nsimulation of the motion of defects in a zenithal bistable liquid crystal\ndevice.",
        "positive": "Stress-stabilized sub-isostatic fiber networks in a rope-like limit: The mechanics of disordered fibrous networks such as those that make up the\nextracellular matrix are strongly dependent on the local connectivity or\ncoordination number. For biopolymer networks this coordination number is\ntypically between three and four. Such networks are sub-isostatic and linearly\nunstable to deformation with only central force interactions, but exhibit a\nmechanical phase transition between floppy and rigid states under strain.\nIntroducing weak bending interactions stabilizes these networks and suppresses\nthe critical signatures of this transition. We show that applying external\nstress can also stabilize sub-isostatic networks with only tensile central\nforce interactions, i.e., a rope-like potential. Moreover, we find that the\nlinear shear modulus shows a power law scaling with the external normal stress,\nwith a non-mean-field exponent. For networks with finite bending rigidity, we\nfind that the critical stain shifts to lower values under prestress."
    },
    {
        "anchor": "A New Monte Carlo Method and Its Implications for Generalized Cluster\n  Algorithms: We describe a novel switching algorithm based on a ``reverse'' Monte Carlo\nmethod, in which the potential is stochastically modified before the system\nconfiguration is moved. This new algorithm facilitates a generalized\nformulation of cluster-type Monte Carlo methods, and the generalization makes\nit possible to derive cluster algorithms for systems with both discrete and\ncontinuous degrees of freedom. The roughening transition in the sine-Gordon\nmodel has been studied with this method, and high-accuracy simulations for\nsystem sizes up to $1024^2$ were carried out to examine the logarithmic\ndivergence of the surface roughness above the transition temperature, revealing\nclear evidence for universal scaling of the Kosterlitz-Thouless type.",
        "positive": "Depletion potential in hard sphere fluids: A versatile new approach for calculating the depletion potential in a hard\nsphere mixture is presented. This is valid for any number of components and for\narbitrary densities. We describe two different routes to the depletion\npotential for the limit in which the density of one component goes to zero.\nBoth routes can be implemented within density functional theory and simulation.\nWe illustrate the approach by calculating the depletion potential for a big\nhard sphere in a fluid of small spheres near a planar hard wall. The density\nfunctional results are in excellent agreement with simulations."
    },
    {
        "anchor": "A thermodynamic approach to the fragility of glass-forming polymers: We have connected the dynamic fragility, namely the rapidity of the\nrelaxation time increase upon temperature reduction, to the excess entropy and\nheat capacity of a large number of glass-forming polymers. The connection was\nobtained in a natural way from the Adam-Gibbs equation, relating the structural\nrelaxation time to the configurational entropy. We find a clear correlation for\na group of polymers. For another group of polymers, for which this correlation\ndoes not work, we emphasise the role of relaxation processes unrelated to the\n&#61537; process in affecting macroscopic thermodynamic properties. Once an\nessentially temperature independent contribution of these processes is removed\nfrom the total excess entropy, the correlation between dynamic fragility and\nthermodynamic properties is re-established.",
        "positive": "The Role of annealed defects on conformational statistics of a\n  selfavoiding semi-flexible polymer chain: Exact Results (I): We study equilibrium statistics of single semi-flexible polymer chain in the\npresence of defects. The defects are lying along a line in the two and three\ndimensions and the monomers are interacting with the onsite potential of the\ndefects. A fully directed self-avoiding walk model is used in two and three\ndimensions to describe thermo-dynamical behaviour of the chain in the presence\nof m defects. We have found that the number of conformations of the\nsemiflexible polymer chain may be controlled by means of introduction of such\ndefects so that a particular fraction of the chain conformations may be either\nsuppressed or populated as per our requirements for synthesizing the\npolymer-nanoaggregates. We discuss the role of annealed defects for its Q\nrealizations and m defects analytically, i. e. when the defects are in the\nthermal equilibrium with the monomers of the semi-flexible chain."
    },
    {
        "anchor": "Non-spectral relaxation in one dimensional Ornstein-Uhlenbeck processes: The relaxation of a dissipative system to its equilibrium state often shows a\nmultiexponential pattern with relaxation rates, which are typically considered\nto be independent of the initial condition. The rates follow from the spectrum\nof a Hermitian operator obtained by a similarity transformation of the initial\nFokker-Planck operator. However, some initial conditions are mapped by this\nsimilarity transformation to functions which grow at infinity. These cannot be\nexpanded in terms of the eigenfunctions of an Hermitian operator, and show\ndifferent relaxation patterns. Considering the exactly solvable examples of\nGaussian and generalized L\\'evy Ornstein-Uhlenbeck processes (OUPs) we show\nthat the relaxation rates belong to the Hermitian spectrum only if the initial\ncondition belongs to the domain of attraction of the stable distribution\ndefining the noise. While for an ordinary OUP initial conditions leading to\nnon-spectral relaxation can be considered exotic, for generalized OUPs driven\nby L\\'evy noise these are the rule.",
        "positive": "Sub-THz complex dielectric constants of montmorillionite clay thin\n  samples with Na$^{+}$/Ca$^{++}$-ions: We implement a technique to characterize electromagnetic properties at\nfrequencies 100 to 165 GHz (3 cm$^{-1}$ to 4.95 cm$^{-1}$) of oriented\nmontmorillionite samples using an open cavity resonator connected to a\nsub-millimeter wave VNA (Vector Network Analyzer). We measured dielectric\nconstants perpendicular to the bedding plane on oriented Na$^{+}$ and\nCa$^{++}$-ion stabilized montmorillionite samples deposited on a glass slide at\nambient laboratory conditions (room temperature and room light). The clay layer\nis much thinner ($\\sim$ 30 $\\mu$m) than the glass substrate ($\\sim$ 2.18 mm).\nThe real part of dielectric constant,$\\epsilon_{re}$, is essentially constant\nover this frequency range but is larger in Na$^{+}$- than in Ca$^{++}$-ioned\nclay. The total electrical conductivity (associated with the imaginary part of\ndielectric constant, $\\epsilon_{im}$) of both samples increases monotonically\nat lower frequencies ($<$ 110 GHz), but shows rapid increase for Na$^{+}$ ions\nin the regime $>$ 110 GHz. The dispersion of the samples display a dependence\non the ionic strength in the clay interlayers, i.e., $\\zeta$-potential in the\nStern layers."
    },
    {
        "anchor": "Solvent-induced morphological transitions in methacrylate-based\n  block-copolymer aggregates: Poly(ethylene oxide)-$\\textit{b}$-poly(butylmethacrylate)\n(PEO-$\\textit{b}$-PBMA) copolymers have recently been identified as excellent\nbuilding blocks for the synthesis of hierarchical nanoporous materials.\nNevertheless, while experiments have unveiled their potential to form\nbicontinuous phases and vesicles, a general picture of their phase and\naggregation behavior is still missing. By performing Molecular Dynamics\nsimulations, we here apply our recent coarse-grained model of\nPEO-$\\textit{b}$-PBMA to investigate its self-assembly in water and\ntetrahydrofuran (THF) and unveil the occurrence of a wide spectrum of\nmesophases. In particular, we find that the morphological phase diagram of this\nternary system incorporates bicontinuous and lamellar phases at high copolymer\nconcentrations, and finite-size aggregates, such as dispersed sheets or\ndisk-like aggregates, spherical vesicles and rod-like vesicles, at low\ncopolymer concentrations. The morphology of these mesophases can be controlled\nby tuning the THF/water relative content, which has a striking effect on the\nkinetics of self-assembly as well as on the resulting equilibrium structures.\nOur results disclose the fascinating potential of PEO-$\\textit{b}$-PBMA\ncopolymers for the templated synthesis of nanostructured materials and offer a\nguideline to fine-tune their properties by accurately selecting the THF/water\nratio.",
        "positive": "Phase coexistence of cluster crystals: beyond the Gibbs phase rule: We report a study of the phase behavior of multiple-occupancy crystals\nthrough simulation. We argue that in order to reproduce the equilibrium\nbehavior of such crystals it is essential to treat the number of lattice sites\nas a constraining thermodynamic variable. The resulting free-energy\ncalculations thus differ considerably from schemes used for single-occupancy\nlattices. Using our approach, we obtain the phase diagram and the bulk modulus\nfor a generalized exponential model that forms cluster crystals at high\ndensities. We compare the simulation results with existing theoretical\npredictions. We also identify two types of density fluctuations that can lead\nto two sound modes and evaluate the corresponding elastic constants."
    },
    {
        "anchor": "Shocks in supersonic sand: We measure time-averaged velocity, density, and temperature fields for steady\ngranular flow past a wedge and calculate a speed of granular pressure\ndisturbances (sound speed) equal to 10% of the flow speed. The flow is\nsupersonic, forming shocks nearly identical to those in a supersonic gas.\nMolecular dynamics simulations of Newton's laws and Monte Carlo simulations of\nthe Boltzmann equation yield fields in quantitative agreement with experiment.\nA numerical solution of Navier-Stokes-like equations agrees with a molecular\ndynamics simulation for experimental conditions excluding wall friction.",
        "positive": "Out-of-contact elastohydrodynamic deformation due to lubrication forces: We characterize the spatiotemporal deformation of an elastic film during the\nradial drainage of fluid from a narrowing gap. Elastic deformation of the film\ntakes the form of a dimple and prevents full contact to be reached. With\nthinner elastic film the stress becomes increasingly supported by the\nunderlying rigid substrate and the dimple formation is suppressed, which allows\nthe surfaces to reach full contact. We highlight the lag due to viscoelasticity\non the surface profiles, and that for a given fluid film thickness deformation\nleads to stronger hydrodynamic forces than for rigid surfaces."
    },
    {
        "anchor": "Topologically protected colloidal transport above a square magnetic\n  lattice: We theoretically study the motion of magnetic colloidal particles above a\nmagnetic pattern and compare the predictions with Brownian dynamics\nsimulations. The pattern consists of alternating square domains of positive and\nnegative magnetization. The colloidal motion is driven by periodic modulation\nloops of an external magnetic field. There exist loops that induce\ntopologically protected colloidal transport between two different unit cells of\nthe pattern. The transport is very robust against internal and external\nperturbations. Theory and simulations are in perfect agreement.",
        "positive": "Knotting probability of self-avoiding polygons under a topological\n  constraint: We define the knotting probability of a knot $K$ by the probability for a\nrandom polygon (RP) or self-avoiding polygon (SAP) of $N$ segments having the\nknot type $K$. We show fundamental and generic properties of the knotting\nprobability particularly its dependence on the excluded volume. We investigate\nthem for the SAP consisting of hard cylindrical segments of unit length and\nradius $r_{\\rm ex}$. For various prime and composite knots we numerically show\nthat a compact formula describes the knotting probabilities for the cylindrical\nSAP as a function of segment number $N$ and radius $r_{\\rm ex}$. It connects\nthe small-$N$ to the large-$N$ behavior and even to lattice knots in the case\nof large values of radius. As the excluded volume increases the maximum of the\nknotting probability decreases for prime knots except for the trefoil knot. If\nit is large, the trefoil knot and its descendants are dominant among the\nnontrivial knots in the SAP. From the factorization property of the knotting\nprobability we derive a relation among the estimates of a fitting parameter for\nall prime knots, which suggests the local knot picture. Here we remark that the\ncylindrical SAP gives a model of circular DNA which are negatively charged and\nsemiflexible, where radius $r_{\\rm ex}$ corresponds to the screening length."
    },
    {
        "anchor": "Microoptomechanical pumps assembled and driven by holographic optical\n  vortex arrays: Beams of light with helical wavefronts can be focused into ring-like optical\ntraps known as optical vortices. The orbital angular momentum carried by\nphotons in helical modes can be transferred to trapped mesoscopic objects and\nthereby coupled to a surrounding fluid. We demonstrate that arrays of optical\nvortices created with the holographic optical tweezer technique can assemble\ncolloidal spheres into dynamically reconfigurable microoptomechanical pumps\nassembled by optical gradient forces and actuated by photon orbital angular\nmomentum.",
        "positive": "Hydrodynamic Self-Consistent Field Theory for Inhomogeneous Polymer\n  Melts: We introduce a mesoscale technique for simulating the structure and rheology\nof block copolymer melts and blends in hydrodynamic flows. The technique\ncouples dynamic self consistent field theory (DSCFT) with continuum\nhydrodynamics and flow penalization to simulate polymeric fluid flows in\nchannels of arbitrary geometry. We demonstrate the method by studying phase\nseparation of an ABC triblock copolymer melt in a sub-micron channel with\nneutral wall wetting conditions. We find that surface wetting effects and shear\neffects compete, producing wall-perpendicular lamellae in the absence of flow,\nand wall-parallel lamellae in cases where the shear rate exceeds some critical\nWeissenberg number."
    },
    {
        "anchor": "Like-charge attraction at the nanoscale: ground-state correlations and\n  water destructuring: Like-charge attraction, driven by ionic correlations, challenges our\nunderstanding of electrostatics both in soft and hard matter. For two charged\nplanar surfaces confining counterions and water, we prove that even at\nrelatively low correlation strength, the relevant physics is the ground-state\none, oblivious of fluctuations. Based on this, we derive a simple and accurate\ninteraction pressure, that fulfills known exact requirements and can be used as\nan effective potential. We test this equation against implicit-solvent Monte\nCarlo simulations and against explicit-solvent simulations of cement and\nseveral types of clays. We argue that water destructuring under nanometric\nconfinement drastically reduces dielectric screening, enhancing ionic\ncorrelations. Our equation of state at reduced permittivity therefore explains\nthe exotic attractive regime reported for these materials, even in absence of\nmultivalent counterions.",
        "positive": "Topological defects and geometric memory across the nematic-smectic A\n  liquid crystal phase transition: We study transformations of self-organized defect arrays at the\nnematic-smectic A liquid crystal phase transition, and show that these defect\nconfigurations are correlated, or \"remembered\", across the phase transition. A\nthin film of thermotropic liquid crystal is subjected to hybrid anchoring by an\nair interface and a water substrate, and viewed under polarized optical\nmicroscopy. Upon heating from smectic-A to nematic, a packing of focal conic\ndomains melts into a dense array of boojums---nematic surface defects---which\nthen coarsens by pair-annihilation. With the aid of Landau-de Gennes numerical\nmodeling, we elucidate the topological and geometrical rules underlying this\ntransformation. In the transition from nematic to smectic-A, we show that focal\nconic domain packings are organized over large scales in patterns that retain a\ngeometric memory of the nematic boojum configuration, which can be recovered\nwith remarkable fidelity."
    },
    {
        "anchor": "Non-monotonic variation with salt concentration of the second virial\n  coefficient in protein solutions: The osmotic virial coefficient $B_2$ of globular protein solutions is\ncalculated as a function of added salt concentration at fixed pH by computer\nsimulations of the ``primitive model''. The salt and counter-ions as well as a\ndiscrete charge pattern on the protein surface are explicitly incorporated. For\nparameters roughly corresponding to lysozyme, we find that $B_2$ first\ndecreases with added salt concentration up to a threshold concentration, then\nincreases to a maximum, and then decreases again upon further raising the ionic\nstrength. Our studies demonstrate that the existence of a discrete charge\npattern on the protein surface profoundly influences the effective interactions\nand that non-linear Poisson Boltzmann and Derjaguin-Landau-Verwey-Overbeek\n(DLVO) theory fail for large ionic strength. The observed non-monotonicity of\n$B_2$ is compared to experiments. Implications for protein crystallization are\ndiscussed.",
        "positive": "Theory of unconventional singularities of frictional shear cracks: Crack-like objects that propagate along frictional interfaces,\ni.e.~frictional shear cracks, play a major role in a broad range of frictional\nphenomena. Such frictional cracks are commonly assumed to feature the universal\nsquare root near-edge singularity of ideal shear cracks, as predicted by Linear\nElastic Fracture Mechanics. Here we show that this is not the generic case due\nto the intrinsic dependence of the frictional strength on the slip rate, even\nif the bodies forming the frictional interface are identical and predominantly\nlinear elastic. Instead, frictional shear cracks feature unconventional\nsingularities characterized by a singularity order $\\xi$ that differs from the\nconventional $-\\tfrac{1}{2}$ one. It is shown that $\\xi$ depends on the\nfriction law, on the propagation speed and on the symmetry mode of loading. We\ndiscuss the general structure of a theory of unconventional singularities,\nalong with their implications for the energy balance and dynamics of frictional\ncracks. Finally, we present explicit calculations of $\\xi$ and the associated\nnear-edge fields for linear viscous-friction -- which may emerge as a\nperturbative approximation of nonlinear friction laws or on its own -- for both\nin-plane (mode-II) and anti-plane (mode-III) shear loadings."
    },
    {
        "anchor": "Dynamics of Polymer Ejection from a Nano-sphere: Polymer ejection from nano-confinement has been of interest due to its\nrelation to various fundamental sciences and applications. However, the\nejection dynamics of a polymer with different persistence lengths from\nconfinement through a nanopore is still poorly understood. In this manuscript,\na theory is developed for the ejection dynamics of a polymer with the total\nlength $L_0$ and persistence length $l$ from a sphere of diameter $D$. These\nlength-scales specify different regimes, which determine the polymer dynamics\nand its ejection rate. It is seen that the polymer undergoes between two to\nthree confinement regimes, in some cases. The total ejection time $\\tau$\ndepends on the polymer dynamics in various relevant regimes that the polymer\nexperiences. Dependence of the ejection time on the system parameters is\ndiscussed according to the theory. The theory predicts that $\\alpha$ in $\\tau\n\\sim L_0^{\\alpha}$ changes between 1 and 1.7, $\\beta$ in $\\tau \\sim D^{\\beta}$\nchanges between 3 and 5, and $\\gamma$ in $\\tau \\sim l^{\\gamma}$ is often\nsmaller than 1, in the studied range of the parameters.",
        "positive": "Low-energy photoelectron transmission through aerosol overlayers: The transmission of low-energy (<1.8eV) photoelectrons through the shell of\ncore-shell aerosol particles is studied for liquid squalane, squalene, and DEHS\nshells. The photoelectrons are exclusively formed in the core of the particles\nby two-photon ionization. The total photoelectron yield recorded as a function\nof shell thickness (1-80nm) shows a bi-exponential attenuation. For all\nsubstances, the damping parameter for shell thicknesses below 15nm lies between\n8 and 9nm, and is tentatively assigned to the electron attenuation length at\nelectron kinetic energies of ~0.5-1eV. The significantly larger damping\nparameters for thick shells (> 20nm) are presumably a consequence of distorted\ncore-shell structures. A first comparison of aerosol and traditional thin film\noverlayer methods is provided."
    },
    {
        "anchor": "Impedance of a sphere oscillating in an elastic medium with and without\n  slip: The dynamic impedance of a sphere oscillating in an elastic medium is\nconsidered. Oestreicher's formula for the impedance of a sphere bonded to the\nsurrounding medium can be expressed simply in terms of three lumped impedances\nassociated with the displaced mass and the longitudinal and transverse waves.\nIf the surface of the sphere slips while the normal velocity remains\ncontinuous, the impedance formula is modified by adjusting the definition of\nthe transverse impedance to include the interfacial impedance.",
        "positive": "Kinetic theory of Hyaluronan cleavage by Bovine Testicular Hyaluronidase\n  in Standard and Crowded Environments: ${\\bf Background}$ Details of the kinetic pathways governing enzymatic\ncleavage of hyaluronic acid (HA) by hyaluronidase are still widely uncharted.\nCapillary electrophoresis-based assays were used for accurate quantification of\nenzymatic products. A crowding agent was also employed to mimic excluded-volume\nconstraints typical of in-vivo conditions.\n  $ {\\bf Scope}$ Introduce a comprehensive kinetic model describing the\nlate-stage degradation of HA by hyaluronidase and identify the relevant kinetic\npathways and the associated rates.\n  ${\\bf Major Conclusions}$ All relevant fragmentation and transglycosylation\npathways and rates were identified. Two dimers forming a tetramer is the\ndominant recombination pathway. Macromolecular and self-crowding slow down the\nkinetics but do not alter the underlying mechanisms.\n  ${\\bf General Significance}$ Our results bring a novel and comprehensive\nquantitative insight into enzymatic HA degradation. Rationalizing the effect of\ncrowding brings the intricate conditions of in-vivo settings a little closer,\nand also stands as a powerful tool to pinpoint relevant kinetic pathways in\ncomplex systems."
    },
    {
        "anchor": "A fractal classification of the drainage dynamics in thin liquid films: It is demonstrated that the dynamic structure is very important for the rate\nof drainage of a thin liquid film and it can be effectively taken into account\nby a dynamic fractal dimension. It is shown that the latter is a powerful tool\nfor description of the film drainage and classifies all the known results from\nthe literature. The obtained general expression for the thinning rate is a\nheuristic one and predicts variety of drainage models, which are even difficult\nto simulate in practice. It is a typical example of a scaling law, which\nexplains the origin of the complicate dependence of the thinning rate on the\nfilm radius.",
        "positive": "Organization and instabilities of entangled active polar filaments: We study the dynamics of an entangled, isotropic solution of polar filaments\ncoupled by molecular motors which generate relative motion of the filaments in\ntwo and three dimensions. We investigate the stability of the homogeneous state\nfor constant motor concentration taking into account excluded volume and\nentanglement. At low filament density the system develops a density\ninstability, while at high filament density entanglement effects drive the\ninstability of orientational fluctuations."
    },
    {
        "anchor": "Properties of compressible elastica from relativistic analogy: Kirchhoff's kinetic analogy relates the deformation of an incompressible\nelastic rod to the classical dynamics of rigid body rotation. We extend the\nanalogy to compressible filaments and find that the extension is similar to the\nintroduction of relativistic effects into the dynamical system. The extended\nanalogy reveals a surprising symmetry in the deformations of compressible\nelastica. In addition, we use known results for the buckling of compressible\nelastica to derive the explicit solution for the motion of a relativistic\nnonlinear pendulum. We discuss cases where the extended Kirchhoff analogy may\nbe useful for the study of other soft matter systems.",
        "positive": "Reconfiguration, Interrupted Aging and Enhanced Dynamics of a Colloidal\n  Gel using Photo-Switchable Active Doping: We study light-activated quasi-2d gels made of a colloidal network doped with\nJanus particles. Following the gel formation, the internal dynamics of the gel\nare monitored before, during, and after the light activation. We monitor both\nthe structure and dynamics, before, during and after the illumination period.\nThe mobility of the passive particles exhibits a characteristic scale-dependent\nresponse. Immediately following light activation, the gel displays large-scale\nreorganization, followed by progressive, short-scale displacements throughout\nthe activation period. Albeit subtle structural changes (including pore opening\nand widening and shortening of strands) the colloidal network remains\nconnected, and the gel maintains its structural integrity. Once activity is\nswitched off, the gel keeps the memory of the structure inherited from the\nactive phase. Remarkably, the motility remains larger than that of the gel,\nbefore the active period. The system has turned into a genuinely different gel,\nwith frozen dynamics, but with more space for thermal fluctuations. The above\nconclusions remain valid long after the activity period."
    },
    {
        "anchor": "Multiple phoretic mechanisms in the self-propulsion of a Pt-insulator\n  Janus swimmer: We present a detailed theoretical study which demonstrates that\nelectrokinetic effects can also play a role in the motion of metallic-insulator\nspherical Janus particles. Essential to our analysis is the identification of\nthe fact that the reaction rates depend on Pt- coating thickness and that the\nthickness of coating varies from pole to equator of the coated hemisphere. We\nfind that their motion is due to a combination of neutral and ionic\ndiffusiophoretic as well as electrophoretic effects whose interplay can be\nchanged by varying the ionic properties of the fluid. This has great potential\nsignificance for optimising performance of designed synthetic swimmers.",
        "positive": "Active microrheology of Chaetopterus mucus determines three intrinsic\n  lengthscales that govern material properties: We characterize the scale-dependent rheological properties of mucus from the\nChaetopterus marine worm and determine the intrinsic lengthscales controlling\ndistinct rheological and structural regimes. Mucus produced by this ubiquitous\nfilter feeder serves a host of roles including filtration, protection and\ntrapping nutrients. The ease of clean mucus extraction coupled with\nsimilarities to human mucus rheology also make Chaetopterus mucus a potential\nmodel system for elucidating human mucus mechanics. We use optically trapped\nmicrosphere probes of 2-10 microns, to induce oscillatory strains and measure\nmucus stress response. We show that viscoelastic properties are highly\ndependent on the strain scale (l) with three distinct regimes emerging:\nmicroscale: l_1<4 microns, mesoscale: l_2~4-10 microns, and macroscale: l_3>10\nmicrons. While mucus response is similar to water for l_1 indicating that\nprobes rarely contact the mucus mesh, for l_2 the response is distinctly more\nviscous and independent of probe size, demonstrating that the mucus behaves as\na continuum. However, this principally viscous mesoscale response is distinct\nfrom the largely elastic macroscopic mucus response. Only for l_3 does the\nresponse mimic macroscopic elasticity, with rigid constraints strongly\nresisting microsphere displacement. Our results demonstrate that a uniform mesh\nmodel for mucus with a single lengthscale modulating the crossover from\nwater-like to elastic is too simplistic. Rather, the mucus responds as a\nhierarchical network with a loose microscopic mesh controlling mechanics for\nl_2, coupled with a mesoscale rigid scaffold responsible for the macroscopic\ngel-like mechanics beyond l_3. Our results shed important new light onto the\ndesign of drug delivery platforms, preventing pathogen penetration, and\nimproving filtration, coating and clearance capabilities of mucus."
    },
    {
        "anchor": "Capillary interactions in Pickering emulsions: The effective capillary interaction potentials for small colloidal particles\ntrapped at the surface of liquid droplets are calculated analytically. Pair\npotentials between capillary monopoles and dipoles, corresponding to particles\nfloating on a droplet with a fixed center of mass and subjected to external\nforces and torques, respectively, exhibit a repulsion at large angular\nseparations and an attraction at smaller separations, with the latter\nresembling the typical behavior for flat interfaces. This change of character\nis not observed for quadrupoles, corresponding to free particles on a\nmechanically isolated droplet. The analytical results for quadrupoles are\ncompared with the numerical minimization of the surface free energy of the\ndroplet in the presence of ellipsoidal particles.",
        "positive": "Extension of the Hertz model for accounting to surface tension in\n  nano-indentation tests of soft materials: The contact between a spherical indenter and a solid is considered. A\nnumerical finite element model (F. E. M) to taking into account the surface\ntension of the solid is presented and assessed. It is shown that for\nnano-indentation of soft materials, the surface tension of the solid influences\nsignificantly the reaction force due to indentation. The validity of the\nclassical Hertz model is defined. In very good approximation, the force vs.\nindentation depth curve can be fitted by a power law function $F=a^\\delta b$\nwhere $F$ denotes the force acting on the indentor, $d$ the indentation depth,\n$a$ and $b\\in\\ ]1,1.5]$ are constants depending on the materials and the size\nof the indentor."
    },
    {
        "anchor": "Kinetic Theory of Soft Matter. The Penetrable-Square-Well Model: The penetrable-square-well (PSW) pair interaction potential is defined as\n$\\phi (r)=\\epsilon_r$ if the two interacting particles are overlapped\n($r<\\sigma$), $\\phi(r)=-\\epsilon_a$ inside a corona ($\\sigma <r<\\lambda$), and\n$\\phi(r)=0$ otherwise ($r>\\lambda$). Thus, the potential reduces to the\nconventional square-well (SW) one in the limit $\\epsilon_r\\to\\infty$ and to the\npenetrable-sphere (PS) potential if $\\epsilon_a\\to0$ or $\\lambda\\to\\sigma$.\nThis paper aims at studying the temperature dependence of the Navier--Stokes\ntransport coefficients of a dilute gas of particles interacting via the PSW\nmodel. By exploiting the fact that the PSW scattering process is analogous to\nthat of a light ray passing through two concentric spherical media with\ndifferent refractive indices, the scattering angle is analytically derived as a\nfunction of the impact parameter and the relative velocity of the colliding\nparticles; depending on the values of those two quantities, collisions can be\nsoft, hard, or grazing. Next, by standard application of known general results\nfrom the Chapman--Enskog method, the Navier--Stokes transport coefficients in\nthe first-order approximation are numerically evaluated. It is found that the\nPSW coefficients are practically indistinguishable from the SW ones for\ntemperatures low enough ($k_BT\\lesssim 0.2 \\epsilon_r$), there exists a\ntransition regime ($0.2 \\epsilon_r\\lesssim k_BT\\lesssim 10\\epsilon_r$) where\nthe transport coefficients interpolate between the SW and the PS ones, and\nfinally the PSW coefficients are comparable to the PS ones for high enough\ntemperatures ($k_BT\\gtrsim 10\\epsilon_r$). The results are applied to the\ntemperature profiles of the planar Fourier flow.",
        "positive": "Transient instabilities in swelling dynamics: We investigate the swelling dynamics driven by solvent absorption in a\nhydrogel sphere immersed in a solvent bath, through an accurate computational\nmodel and numerical study. We extensively describe the transient process from\ndry to wet and discuss the onset of surface instabilities through a measure of\nthe lack of smoothness of the outer surface and a morphological pattern of that\nsurface with respect to the two material parameters driving the swelling\ndynamics."
    },
    {
        "anchor": "Flocculation of vesicles: The flocculation of liposomes is theoretically studied. An expression for the\nflocculation activation energy is derived, accounting for the electrostatic and\nhydrophobic interactions as well as for the correlation area of floc-spots.",
        "positive": "Membrane adhesion via competing receptor/ligand bonds: The adhesion of biological membranes is controlled by various types of\nreceptor and ligand molecules. In this letter, we present a\nstatistical-mechanical model for membranes that interact via receptor/ligand\nbonds of two different lengths. We show that the equilibrium phase behavior of\nthe membranes is governed by an effective double-well potential. The depths of\nthe two potential wells depend on the concentrations and binding energies of\nthe receptors and ligands. The membranes are unbound for small, and bound for\nlarger potential depths. In the bound state, the length mismatch of the\nreceptor/ligand bonds can lead to lateral phase separation. We derive explicit\nscaling laws for the critical points of unbinding and phase separation, and\ndetermine the prefactors by comparison with Monte Carlo results."
    },
    {
        "anchor": "How to puncture a biomembrane: elastic versus entropic rupture: A very common strategy to penetrate the cell membrane and access the internal\ncompartment, consists of using sharp tips or nano needles. However recent\nexperiments of cell penetration by atomic force microscopy tips show, contrary\nto expectations, a weak dependence of penetration force on the curvature of the\ntip. Using molecular dynamics simulations and analytical arguments, here we\nshow that membrane disruption can be driven either by elastic or entropic\nforces depending on the membrane size. Our findings have potentially relevant\nimplications in tissue engineering and drug delivery, as they help assessing\nthe effectiveness of the most common membranes penetration methods.",
        "positive": "Time-dependent homogeneous states of binary granular suspensions: The time evolution of a homogeneous bidisperse granular suspension is studied\nin the context of the Enskog kinetic equation. The influence of the surrounding\nviscous gas on the solid particles is modeled via a deterministic viscous drag\nforce plus a stochastic Langevin-like term. It is found first that, regardless\nof the initial conditions, the system reaches (after a transient period lasting\na few collisions per particle) a universal unsteady hydrodynamic regime where\nthe distribution function of each species not only depends on the dimensionless\nvelocity (as in the homogeneous cooling state) but also on the instantaneous\ntemperature scaled with respect to the background temperature. To confirm this\nresult, theoretical predictions for the time-dependent partial temperatures are\ncompared against direct simulation Monte Carlo (DSMC) results; the comparison\nshows an excellent agreement confirming the applicability of hydrodynamics in\ngranular suspensions. Also, in the transient regime, the so-called Mpemba-like\neffect (namely, when an initially hotter sample cools sooner than the colder\none) is analyzed for inelastic collisions. The theoretical analysis of the\nMpemba effect is performed for initial states close to and far away from the\nasymptotic steady state. In both cases, a good agreement is found again between\ntheory and DSMC results. As a complement of the previous studies, we determine\nin this paper the dependence of the steady values of the dynamic properties of\nthe suspension on the parameter space of the system. More specifically, we\nfocus on our attention in the temperature ratio $T_1/T_2$ and the fourth degree\ncumulants $c_1$ and $c_2$ (measuring the departure of the velocity\ndistributions $f_1$ and $f_2$ from their Maxwellian forms). Finally, a linear\nstability analysis of the steady state solution is also carried out showing\nthat the steady state is always linearly stable."
    },
    {
        "anchor": "Boundary Effects in Chiral Polymer Hexatics: Boundary effects in liquid-crystalline phases can be large due to long-ranged\norientational correlations. We show that the chiral hexatic phase can be locked\ninto an apparent three-dimensional N+6 phase via such effects. Simple numerical\nestimates suggest that the recently discovered \"polymer hexatic\" may actually\nbe this locked phase.",
        "positive": "Designing highly efficient lock-and-key interactions in anisotropic\n  active particles: Cluster formation of microscopic swimmers is key to the formation of biofilms\nand colonies, efficient motion and nutrient uptake, but, in the absence of\nother interactions, requires high swimmer concentrations to occur. Here we\nexperimentally and numerically show that cluster formation can be dramatically\nenhanced by an anisotropic swimmer shape. We analyze a class of model\nmicroswimmers with a shape that can be continuously tuned from spherical to\nbent and straight rods. In all cases, clustering can be described by\nMichaelis-Menten kinetics governed by a single scaling parameter that depends\non particle density and shape only. We rationalize these shape-dependent\ndynamics from the interplay between interlocking probability and cluster\nstability. The bent rod shape promotes assembly even at vanishingly low\nparticle densities and we identify the most efficient shape to be a semicircle.\nOur work provides key insights into how shape can be used to rationally design\nout-of-equilibrium self-organization, key to creating active functional\nmaterials and designing targeted two-component drug delivery."
    },
    {
        "anchor": "The interaction of frictional slip and adhesion for a stiff sphere on a\n  compliant substrate: How friction affects adhesion is addressed. The problem is considered in the\ncontext of a very stiff sphere adhering to a compliant, isotropic, linear\nelastic substrate, and experiencing adhesion and frictional slip relative to\neach other. The adhesion is considered to be driven by very large attractive\ntractions between the sphere and the substrate that can act only at very small\ndistances between them. As a consequence, the adhesion behavior can be\nrepresented by the Johnson-Kendall-Roberts model, and this is assumed to\nprevail also when frictional slip is occurring. Frictional slip is considered\nto be resisted by a uniform, constant shear traction at the slipping interface,\na model that is considered to be valid for small asperities and for compliant\nelastomers in contact with stiff material. A model for the interaction of\nfriction and adhesion, known to agree with some experimental data, is utilized.\nThis model is due to Johnson, and its adhesion-friction interaction is assumed\nto stem, upon shrinkage of the contact area, from a postulated reversible\nenergy release associated with frictional slip. This behavior is considered to\narise from surface microstructures generated or eliminated by frictional slip,\nwhere these microstructures store some elastic strain energy in a reversible\nmanner. The associated reversible energy release rate is derived from the\nenergy exchanges that occur in the system. The Johnson model, and an asymptotic\nanalysis of it for small amounts of frictional slip, is shown to be consistent\nwith the reversible energy release rate that we identify.",
        "positive": "Flagellar Synchronization Through Direct Hydrodynamic Interactions: Microscale fluid flows generated by ensembles of beating eukaryotic flagella\nare crucial to fundamental processes such as development, motility and sensing.\nDespite significant experimental and theoretical progress, the underlying\nphysical mechanisms behind this striking coordination remain unclear. Here, we\npresent a novel series of experiments in which the flagellar dynamics of two\nmicropipette-held somatic cells of Volvox carteri, with measurably different\nintrinsic beating frequencies, are studied by high-speed imaging as a function\nof their mutual separation and orientation. From analysis of beating time\nseries we find that the interflagellar coupling, which is constrained by the\nlack of chemical and mechanical connections between the cells to be purely\nhydrodynamical, exhibits a spatial dependence that is consistent with\ntheoretical predictions. At close spacings it produces robust synchrony which\ncan prevail for thousands of flagellar beats, while at increasing separations\nthis synchrony is systematically degraded by stochastic processes. Manipulation\nof the relative flagellar orientation reveals the existence of both in-phase\nand antiphase synchronized states, which is consistent with dynamical theories.\nThrough dynamic flagellar tracking with exquisite spatio-temporal precision, we\nquantify changes in beating waveforms that result from altered coupling\nconfiguration and distance of separation. The experimental results of this\nstudy prove unequivocally that flagella coupled solely through a fluid medium\ncan achieve robust synchrony despite significant differences in their intrinsic\nproperties."
    },
    {
        "anchor": "Relationships among structure, memory, and flow in sheared disordered\n  materials: A fundamental challenge for disordered solids is predicting macroscopic yield\nfrom the microscopic arrangements of constituent particles. Yield is\naccompanied by a sudden and large increase in energy dissipation due to the\nonset of plastic rearrangements. This suggests that one path to understanding\nbulk rheology is to map particle configurations to their mode of deformation.\nHere, we perform laboratory experiments and numerical simulations that are\ndesigned to do just that: 2D dense colloidal systems are subjected to\noscillatory shear, and particle trajectories and bulk rheology are measured. We\nquantify particle microstructure using excess entropy. Results reveal a direct\nrelation between excess entropy and energy dissipation, that is insensitive to\nthe nature of interactions among particles. We use this relation to build a\nphysically-informed model that connects rheology to microstructure. Our\nfindings suggest a framework for tailoring the rheological response of\ndisordered materials by tuning microstructural properties.",
        "positive": "Spontaneous synchronization of two bistable pyridine-furan nanosprings\n  connected by an oligomeric bridge: The intensive development of nanodevices acting as two-state systems has\nmotivated the search for nanoscale molecular structures whose long-term\nconformational dynamics are similar to the dynamics of bistable mechanical\nsystems such as Euler arches and Duffing oscillators. Collective synchrony in\nbistable dynamics of molecular-sized systems has attracted immense attention as\na potential pathway to amplify the output signals of molecular nanodevices.\nRecently, pyridin-furan oligomers of helical shape that are a few nanometers in\nsize and exhibit bistable dynamics similar to a Duffing oscillator have been\nidentified through molecular dynamics simulations. In this article, we present\nthe case of dynamical synchronization of these bistable systems. We show that\ntwo pyridine-furan springs connected by a rigid oligomeric bridge spontaneously\nsynchronize vibrations and stochastic resonance enhances the synchronization\neffect."
    },
    {
        "anchor": "How Generic are the Robust Theoretical Aspects of Jamming in Hard Sphere\n  Models?: In very recent work the mean field theory of the jamming transition in\ninfinite dimensional hard spheres models was presented. Surprisingly, this\ntheory predicts quantitatively numerically determined characteristics of\njamming in two and three dimensions. This is a rare and unusual finding. Here\nwe argue that this agreement in non-generic: only for hard sphere models it\nhappens that sufficiently close to jamming the effective interactions are in\nagreement with mean-field theory, justifying the truncation of many body\ninteractions (which is the exact protocol in infinite dimensions). Any\nsoftening of the bare hard sphere interactions results in effective\ninteractions that are not mean-field all the way to jamming, making the\ndiscussed phenomenon non generic.",
        "positive": "On the influence of the intermolecular potential on the wetting\n  properties of water on silica surfaces: We study the wetting properties of water on silica surfaces using molecular\ndynamics (MD) simulations. To describe the intermolecular interaction between\nwater and silica atoms, two types of interaction potential models are used: the\nstandard Br\\'odka and Zerda (BZ) model, and the Gulmen and Thompson (GT) model.\nWe perform an in-depth analysis of the influence of the choice of the potential\non the arrangement of the water molecules in partially filled pores and on top\nof silica slabs. We find that at moderate pore filling ratios, the GT silica\nsurface is completely wetted by water molecules, which agrees well with\nexperimental findings, while the commonly used BZ surface is less hydrophilic\nand is only partially wetted. We interpret our simulation results using an\nanalytical calculation of the phase diagram of water in partially filled pores.\nMoreover, an evaluation of the contact angle of the water droplet on top of the\nsilica slab reveals that the interaction becomes more hydrophilic with\nincreasing slab thickness and saturates around 2.5-3 nm, in agreement with the\nexperimentally found value. Our analysis also shows that the hydroaffinity of\nthe surface is mainly determined by the electrostatic interaction, but that the\nvan der Waals interaction nevertheless is strong enough that it can turn a\nhydrophobic surface into a hydrophilic surface."
    },
    {
        "anchor": "Adhesion clusters under shared linear loading: a stochastic analysis: We study the cooperative rupture of multiple adhesion bonds under shared\nlinear loading. Simulations of the appropriate Master equation are compared\nwith numerical integration of a rate equation for the mean number of bonds and\nits scaling analysis. In general, force-accelerated rupture is rather abrupt.\nFor small clusters and slow loading, large fluctuations occur regarding the\ntimepoint of final rupture, but not the typical shape of the rupture\ntrajectory. For vanishing rebinding, our numerical results confirm three\nscaling regimes predicted before for cluster lifetime as a function of loading\nrate. For finite rebinding, the intermediate loading regime becomes irrelevant,\nand a sequence of two new scaling laws can be identified in the slow loading\nregime.",
        "positive": "Efficient Equilibration of Hard Spheres with Newtonian Event Chains: An important task in the simulation of hard spheres and other hard particles\nis structure prediction via equilibration. Event-driven molecular dynamics is\nefficient because its Newtonian dynamics equilibrates fluctuations with the\nspeed of sound. Monte Carlo simulation is efficient if performed with\ncorrelated position updates in event chains. Here, we combine the core concepts\nof molecular dynamics and event chains into a new algorithm involving Newtonian\nevent chains. Measurements of the diffusion coefficient, nucleation rate, and\nmelting speed demonstrate that Newtonian event chains outperform other\nalgorithms. Newtonian event chains scale well to large systems and can be\nextended to anisotropic hard particles without approximations."
    },
    {
        "anchor": "Influence of water models on water movement through AQP1: Water diffusion through membrane proteins is a key aspect of cellular\nfunction. Essential processes of cellular metabolism are driven by osmotic\npressure, which depends on water channels. Membrane proteins such as aquaporins\n(AQPs) are responsible for enabling water transport through the cell membrane.\nAQPs are highly selective, allowing only water and relatively small polar\nmolecules to cross the membrane. Experimentally, estimation of water flux\nthrough membrane proteins is still a challenge, and hence accurate simulations\nof water transport are of particular importance. We present a numerical study\nof water diffusion through AQP1 comparing three water models: TIP3P, OPC and\nTIP4P/2005. Bulk diffusion, diffusion permeability and osmotic permeability are\ncomputed and compared among all models. The results show that there are\nsignificant differences between TIP3P (a particularly widespread model for\nsimulations of biological systems), and the more recently developed TIP4P/2005\nand OPC models. We demonstrate that OPC and TIP4P/2005 reproduce protein-water\ninteractions and dynamics in excellent agreement with experimental data. From\nthis study, we find that the choice of the water model has a significant effect\non the computed water dynamics as well as its molecular behaviour within a\nbiological nanopore.",
        "positive": "Microstructural origins of crushing strength for inherently anisotropic\n  brittle materials: We study the crushing strength of brittle materials whose internal structure\n(e.g., mineral particles or graining) presents a layered arrangement\nreminiscent of sedimentary and metamorphic rocks. Taking a discrete-element\napproach, we probe the failure strength of circular-shaped samples intended to\nreproduce specific mineral configurations. To do so, assemblies of cells,\nproducts of a modified Voronoi tessellation, are joined in mechanically-stable\nlayerings using a bonding law. The cells' shape distribution allows us to set a\nlevel of inherent anisotropy to the material. Using a diametral point loading,\nand systematically changing the loading orientation with respect to the cells'\nconfiguration, we characterize the failure strength of increasingly anisotropic\nstructures. This approach ends up reproducing experimental observations and\nlets us quantify the statistical variability of strength, the consumption of\nthe fragmentation energy, and the induced anisotropies linked to the cell's\ngeometry and force transmission in the samples. Based on a fine description of\ngeometrical and mechanical properties at the onset of failure, we develop a\nmicromechanical breakdown of the crushing strength variability using an\nanalytical decomposition of the stress tensor and the geometrical and force\nanisotropies. We can conclude that the origins of failure strength in\nanisotropic layered media rely on compensations of geometrical and mechanical\nanisotropies, as well as an increasing average radial force between minerals\nindistinctive of tensile or compressive components."
    },
    {
        "anchor": "Turbidimetric evaluation of the solubilization rate: dissolution of\n  dodecane nanodrops in 7.5 mM sodium dodecylsulfate solutions at selected\n  sodium chloride concentrations: The rate of micelle solubilization (SR) can be appraised following the\ndecrease of the radius of a macroscopic drop of oil in contact with a\nsurfactant solution [Todorov, 2002]. Alternatively, the time required for the\ndissolution of a liquid dispersion can be used for this purpose. Here, the\ndecrease of the turbidity of a dodecane-in-water (d/w) nanoemulsion in 7.5 mM\nsodium dodecylsulfate (SDS) is studied at sodium chloride concentrations of\n100, 300, 500, 700, 900, and 1000 mM NaCl. These salinities correspond to\nnon-aggregating (< 300), aggregation-promoted (500) and surfactant\nprecipitation regimes (> 700). It is found that SR is equal to 2.3 x 10^-11,\nhalf the value observed in the absence of salt for a neat aqueous surfactant\nsolution above its critical micelle concentration (7.0 < cmc < 8.7 mM SDS\n[Deodhar, 2020]).",
        "positive": "Time-domain atom interferometry across the threshold for Bose-Einstein\n  condensation: We have performed time-domain interferometry experiments with matter waves\ntrapped in an harmonic potential above and below the Bose-Einstein phase\ntransition. We interrogate the atoms according to the method of separated\noscillating fields, with a sequence of two radio-frequency pulses, separated by\na time delay T. We observe the oscillation of the population between two\ninternal Zeeman states, as a function of the delay T.\n  We find a strong depletion of the interference fringes for both the Bose\ncondensates and the thermal clouds above condensation, even at very short\ntimes, when the clouds are still overlapping. Actually, we explain the observed\nloss of contrast in terms of phase patterns imprinted by the relative motion,\nas a consequence of the entanglement between the internal and external states\nof the trapped atoms."
    },
    {
        "anchor": "Designing circle Swimmers: Principles and strategies: Various microswimmers move along circles rather than straight lines due to\ntheir swimming mechanisms, body shapes or hydrodynamic effects. Here, we adopt\nthe concepts of stochastic thermodynamics to analyze circle swimmers confined\nin a two-dimensional plane, and study the trade-off relations between various\nphysical quantities such as precision, energy cost and rotational speed. Based\non these findings, we predict principles and strategies for designing\nmicroswimmers of special optimized functions under limited energy resource\nconditions, which will bring new experimental inspiration for designing smart\nmotors.",
        "positive": "Extended Short-Range Order Determines the Overall Structure of Liquid\n  Gallium: Polyvalent metal melts (gallium, tin, bismuth, etc.) have microscopic\nstructural features, which are detected by neutron and X-ray diffraction and\nwhich are absent in simple liquids. Based on neutron and X-ray diffraction data\nand results of \\textit{ab initio} molecular dynamics simulations for liquid\ngallium, we examine the structure of this liquid metal at atomistic level.\nTime-resolved cluster analysis allows one to reveal that the short-range\nstructural order in liquid gallium is determined by a range of the correlation\nlengths. This analysis performed over set of independent samples corresponding\nto equilibrium liquid phase discloses that there are no stable crystalline\ndomains as well as molecule-like Ga$_2$ dimers typical for crystal phases of\ngallium. Structure of liquid gallium can be reproduced by the simplified model\nof the close-packed system of soft quasi-spheres. The results can be applied to\nanalyze the fine structure of other polyvalent liquid metals."
    },
    {
        "anchor": "Hidden scale invariance in molecular van der Waals liquids: A simulation\n  study: Results from molecular dynamics simulations of two viscous molecular model\nliquids -- the Lewis-Wahnstrom model of ortho-terphenyl and an asymmetric\ndumbbell model -- are reported. We demonstrate that the liquids have a\n``hidden'' approximate scale invariance: Equilibrium potential energy\nfluctuations are accurately described by inverse power law (IPL) potentials,\nthe radial distribution functions are accurately reproduced by the IPL's, and\nthe radial distribution functions obey the IPL predicted scaling properties to\na good approximation. IPL scaling of the dynamics also applies -- with the\nscaling exponent predicted by the equilibrium fluctuations. In contrast, the\nequation of state does not obey the IPL scaling. We argue that our results are\ngeneral for van der Waals liquids, but do not apply, e.g., for hydrogen-bonded\nliquids.",
        "positive": "Thermal Friction Enhancement in Zwitterionic Monolayers: We introduce a model for zwitterionic monolayers and investigate its\ntribological response to changes in applied load, sliding velocity, and\ntemperature by means of molecular-dynamics simulations. The proposed model\nexhibits different regimes of motion depending on temperature and sliding\nvelocity. We find a remarkable increase of friction with temperature, which we\nattribute to the formation and rupture of transient bonds between individual\nmolecules of opposite sliding layers, triggered by the out-of-plane thermal\nfluctuations of the molecules' orientations. To highlight the effect of the\nmolecular charges, we compare these results with analogous simulations for the\ncharge-free system. These findings are expected to be relevant to nanoscale\nrheology and tribology experiments of locally-charged lubricated systems such\nas, e.g., experiments performed on zwitterionic monolayers, phospholipid\nmicelles, or confined polymeric brushes in a surface force apparatus."
    },
    {
        "anchor": "Periodic thin-film interference filters as one-dimensional photonic\n  crystals: We review photonic band gap related properties of a simple periodic system of\nthin dielectric layers. Properties associated with forbidden and allowed bands\nof such one-dimensional photonic crystals are presented. A revision of\nforbidden bands properties leads to an omnidirectional Bragg mirror design. The\nanisotropy of allowed bands suggests the formation of photon-focusing caustics\nin one-dimensional photonic crystals.",
        "positive": "Flexible fibers in shear flow approach attracting periodic solutions: The three-dimensional dynamics of a single non-Brownian flexible fiber in\nshear flow is evaluated numerically, in the absence of inertia. A wide range of\nratios A of bending to hydrodynamic forces and hundreds of initial\nconfigurations are considered. We demonstrate that flexible fibers in shear\nflow exhibit much more complicated evolution patterns than in the case of\nextensional flow, where transitions to higher-order modes of characteristic\nshapes are observed when A exceeds consecutive threshold values. In shear flow,\nwe identify the existence of an attracting steady configuration and different\nattracting periodic motions that are approached by long-lasting rolling,\ntumbling and meandering dynamical modes, respectively. We demonstrate that the\nfinal stages of the first and second modes are effective Jeffery orbits, with\nthe constant parameter C replaced by an exponential function that either decays\nor increases in time, respectively, corresponding to a systematic drift of the\ntrajectories. In the limit of C going to zero, the fiber aligns with the\nvorticity direction and in the limit of C going to infinity, the fiber\nperiodically tumbles within the shear plane. For moderate values of A, a\nthree-dimensional meandering periodic motion exists, which corresponds to\nintermediate values of C. Transient, close to periodic oscillations are also\ndetected in the first stages of the modes."
    },
    {
        "anchor": "Single and two-cells shape analysis from energy functionals for\n  three-dimensional vertex models: Vertex models have been extensively used for simulating the evolution of\nmulticellular systems, and have given rise to important global properties\nconcerning their macroscopic rheology or jamming transitions. These models are\nbased on the definition of an energy functional, which fully determines the\ncellular response and conclusions. While two-dimensional vertex models have\nbeen widely employed, three-dimensional models are far more scarce, mainly due\nto the large amount of configurations that they may adopt and the complex\ngeometrical transitions they undergo. We here investigate the shape of single\nand two-cells configurations as a function of the energy terms, and we study\nthe dependence of the final shape on the model parameters: namely the exponent\nof the term penalising cell-cell adhesion and surface contractility. In single\ncell analysis, we deduce analytically the radius and limit values of the\ncontractility for linear and quadratic surface energy terms, in 2D and 3D. In\ntwo-cells systems, we deduce the evolution of the aspect ratio. While in\nfunctionals with linear surface terms yield the same aspect ratio in 2D and 3D,\nthe configurations when using quadratic surface terms are distinct. We relate\nour results with well-known solutions from capillarity theory, and verify our\nanalytical findings with a three-dimensional vertex model.",
        "positive": "Nonlinear ac response of anisotropic composites: When a suspension consisting of dielectric particles having nonlinear\ncharacteristics is subjected to a sinusoidal (ac) field, the electrical\nresponse will in general consist of ac fields at frequencies of the\nhigher-order harmonics. These ac responses will also be anisotropic. In this\nwork, a self-consistent formalism has been employed to compute the induced\ndipole moment for suspensions in which the suspended particles have nonlinear\ncharacteristics, in an attempt to investigate the anisotropy in the ac\nresponse. The results showed that the harmonics of the induced dipole moment\nand the local electric field are both increased as the anisotropy increases for\nthe longitudinal field case, while the harmonics are decreased as the\nanisotropy increases for the transverse field case. These results are\nqualitatively understood with the spectral representation. Thus, by measuring\nthe ac responses both parallel and perpendicular to the uniaxial anisotropic\naxis of the field-induced structures, it is possible to perform a real-time\nmonitoring of the field-induced aggregation process."
    },
    {
        "anchor": "Size dependence of second-order hyperpolarizability of finite periodic\n  chain under Su-Schrieffer-Heeger model: The second hyperpolarizability $\\gamma_N(-3\\omega\\omega,\\omega,\\omega)$ of\n$N$ double-bond finite chain of trans-polyactylene is analyzed using the\nSu-Schrieffer-Heeger model to explain qualitative features of the\nsize-dependence behavior of $\\gamma_N$. Our study shows that $\\gamma_N/N$ is\n{\\it nonmonotonic} with $N$ and that the nonmonotonicity is caused by the\ndominant contribution of the intraband transition to $\\gamma_N$ in polyenes.\nSeveral important physical effects are discussed to reduce quantitative\ndiscrepancies between experimental and our results",
        "positive": "Shear-stress controlled dynamics of nematic complex fluids: Based on a mesoscopic theory we investigate the non-equilibrium dynamics of a\nsheared nematic liquid, with the control parameter being the shear stress\n$\\sigma_{\\mathrm{xy}}$ (rather than the usual shear rate, $\\dot\\gamma$). To\nthis end we supplement the equations of motion for the orientational order\nparameters by an equation for $\\dot\\gamma$, which then becomes time-dependent.\nShearing the system from an isotropic state, the stress- controlled flow\nproperties turn out to be essentially identical to those at fixed $\\dot\\gamma$.\nPronounced differences when the equilibrium state is nematic. Here, shearing at\ncontrolled $\\dot\\gamma$ yields several non-equilibrium transitions between\ndifferent dynamic states, including chaotic regimes. The corresponding\nstress-controlled system has only one transition from a regular periodic into a\nstationary (shear-aligned) state. The position of this transition in the\n$\\sigma_{\\mathrm{xy}}$-$\\dot\\gamma$ plane turns out to be tunable by the delay\ntime entering our control scheme for $\\sigma_{\\mathrm{xy}}$. Moreover, a sudden\nchange of the control method can {\\it stabilize} the chaotic states appearing\nat fixed $\\dot\\gamma$."
    },
    {
        "anchor": "Stochastic dynamics of adhesion clusters under shared constant force and\n  with rebinding: Single receptor-ligand bonds have finite lifetimes, so that biological\nsystems can dynamically react to changes in their environment. In cell\nadhesion, adhesion bonds usually act cooperatively in adhesion clusters.\nOutside the cellular context, adhesion clusters can be probed quantitatively by\nattaching receptors and ligands to opposing surfaces. Here we present a\ndetailed theoretical analysis of the stochastic dynamics of a cluster of\nparallel bonds under shared constant loading and with rebinding. Analytical\nsolutions for the appropriate one-step master equation are presented for\nspecial cases, while the general case is treated with exact stochastic\nsimulations. If the completely dissociated state is modeled as an absorbing\nboundary, mean cluster lifetime is finite and can be calculated exactly. We\nalso present a detailed analysis of fluctuation effects and discuss various\napproximations to the full stochastic description.",
        "positive": "Anomalous Front Broadening During Spontaneous Imbibition in a Matrix\n  with Elongated Pores: During spontaneous imbibition a wetting liquid is drawn into a porous medium\nby capillary forces. In systems with comparable pore length and diameter, such\nas paper and sand, the front of the propagating liquid forms a continuous\ninterface. Sections of this interface advance in a highly correlated manner due\nto an effective surface tension, which restricts front broadening. Here we\ninvestigate water imbibition in a nanoporous glass (Vycor) in which the pores\nare much longer than they are wide. In this case, no continuous liquid-vapor\ninterface with coalesced menisci can form. Anomalously fast imbibition front\nroughening is experimentally observed by neutron imaging.We propose a\ntheoretical pore network model, whose structural details are adapted to the\nmicroscopic pore structure of Vycor glass, and show that it displays the same\nlarge scale roughening characteristics as observed in the experiment. The model\npredicts that menisci movements are uncorrelated. This indicates that despite\nthe connectivity of the network the smoothening effect of surface tension on\nthe imbibition front roughening is negligible. These results suggest a new\nuniversality class of imbibition behavior which is expected to occur in any\nmatrix with elongated, interconnected pores of random radii."
    },
    {
        "anchor": "X-ray studies of the phases and phase transitions of liquid crystals: This is a short review of recent x-ray diffraction studies of the phases and\nphase transitions of thermotropic liquid crystals. The areas covered are\ntwist-grain-boundary phases, antiferroelectric phases studied with resonant\nx-ray diffraction, and smectic phases within gel structures. In all areas x-ray\ndiffraction has played a key role. Nonetheless open questions remain: the\nnature of the smectic-C variant of the twist-grain-boundary phase, the origin\nof antiferroelectric phases, and whether novel Bragg glass states exist for\nsmectic-A gel samples.",
        "positive": "Mesoscopic model for colloidal particles, powders and granular solids: A simulation model is presented, comprising elastic spheres with a short\nrange attraction. Besides conservative forces, radial- and shear friction, and\nradial noise are added. The model can be used to simulate colloids, granular\nsolids and powders, and the parameters may be related to experimental systems\nvia the range of attraction and the adhesion energy. The model shares the\nsimplicity and speed of Dissipative Particle Dynamics (DPD), yet the\npredictions are rather non-trivial. We demonstrate that the model predicts the\ncorrect scaling relations for fracture of granular solids, and we present a\nschematic phase diagram. This shows liquid-vapor coexistence for sufficiently\nlarge interaction range, with a surface tension that follows Ising criticality.\nFor smaller interaction range only solid-vapor coexistence is found, but for\nvery small attractive interaction range stable liquid-vapor coexistence\nreappears due to pathological stability of the solid phase. At very low\ntemperature the model forms a glassy state."
    },
    {
        "anchor": "Force-induced Unbinding Dynamics in a Multidimensional Free Energy\n  Landscape: We examined theory for force-induced unbinding on a two-dimensional free\nenergy surface where the internal dynamics of biomolecules is coupled with the\nrupture process under constant tension f. We show that only if the transition\nstate ensemble is narrow and activation barrier is high, the f-dependent\nrupture rate in the 2D potential surface can faithfully be described using an\neffective 1D energy profile.",
        "positive": "A branch-point approximant for the equation of state of hard spheres: Using the first seven known virial coefficients and forcing it to possess two\nbranch-point singularities, a new equation of state for the hard-sphere fluid\nis proposed. This equation of state predicts accurate values of the higher\nvirial coefficients, a radius of convergence smaller than the close-packing\nvalue, and it is as accurate as the rescaled virial expansion and better than\nthe Pad\\'e [3/3] equations of state. Consequences regarding the convergence\nproperties of the virial series and the use of similar equations of state for\nhard-core fluids in $d$ dimensions are also pointed out."
    },
    {
        "anchor": "Collapse and Revival of the Matter Wave Field of a Bose-Einstein\n  Condensate: At the heart of a Bose-Einstein condensate lies its description as a single\ngiant matter wave. Such a Bose-Einstein condensate represents the most\n\"classical\" form of a matter wave, just as an optical laser emits the most\nclassical form of an electromagnetic wave. Beneath this giant matter wave,\nhowever, the discrete atoms represent a crucial granularity, i.e. a\nquantization of this matter wave field. Here we show experimentally that this\nquantization together with the cold collisions between atoms lead to a series\nof collapses and revivals of the coherent matter wave field of a Bose-Einstein\ncondensate. We observe such collapses and revivals directly in the dynamical\nevolution of a multiple matter wave interference pattern, and thereby\ndemonstrate a striking new behaviour of macroscopic quantum matter.",
        "positive": "Density effects on collapse, compression and adhesion of\n  thermoresponsive polymer brushes: We probe, using the Surface Forces Apparatus, the thermal response of\npoly(N-isopropylacrylamide) (PNIPAM) brushes of various grafting densities,\ngrown from plasma-activated mica by means of surface-initiated polymerization.\nWe thus show that dense thermoresponsive brushes collapse gradually as\ntemperature is increased, and that grafting density greatly affects their\nability to swell: the swelling ratio of the brushes, which characterizes the\nthickness variation between the swollen and the collapsed state, is found to\ndecrease from $\\sim 7$ to $\\sim 3$ as the number of grafted chains per unit\narea increases. Such a result, obtained with an unprecedent resolution in\ngrafting density, provides qualitative support to calculations by Mendez {\\it\net al.} [{\\it Macromolecules} {\\bf 2005} {\\it 38}, 174]. We further show that,\nin contrast to swelling, adhesion between two PNIPAM brushes appears to be\nrather insensitive to their molecular structure."
    },
    {
        "anchor": "An energetic model for macromolecules unraveling: We propose a simple approach, based on the minimization of the total\n(entropic plus unfolding) energy of a two-state system, describing the\nstretch-induced unfolding of macromolecules (proteins, silks, nanopolymers,\nDNA/RNA). The model is fully analytical and enlightens the role of the\ndifferent energetic components regulating the unfolding evolution. As an\nexplicit example of application we compare the analytical results with the\ntitin Atomic Force Microscopy experiments showing the ability of the model to\nquantitatively reproduce the mechanical behavior of macromolecules unfolding.",
        "positive": "Contact electrification and the work of adhesion: We present a general theory for the contribution from contact electrification\nto the work necessary to separate two solid bodies. The theory depends on the\nsurface charge density correlation function, which we deduce from Kelvin Force\nMicroscopy (KFM) maps of the surface electrostatic potential. For silicon\nrubber (polydimethylsiloxane, PDMS) we discuss in detail the relative\nimportance of the different contributions to the observed work of adhesion."
    },
    {
        "anchor": "Generalized boundary integral method to investigate the rheology of\n  multiple emulsions of complex internal structures: A generalized boundary integral method is developed to investigate the\nrheology of multiple emulsions with orderly structures up to n layers and up to\nmi droplets in the i-th layer in microchannels with various geometries.\nRecently, as fine templates to prepare microcapsules for targeted drug\ndelivery, multiple emulsions with complex structures have been generated\nthrough microfluidics. The deformation and breakup of multiple emulsions are\ncritical to the transport and release of their inclusion. However, the\nnumerical investigation of the rheology of multiple emulsions is only limited\nto a simple case, i.e., double emulsions with only one core, currently. In this\nletter, two-dimensional boundary element method is employed to study the\nrheology of multiple emulsions under modest outer flows. Especially, the\nhydrodynamics of the engulfed droplets, which might be useful in their\ncontrolled coalescence for chemical reactions and in their controlled release\nfor drug delivery, is investigated. Although the entire particle has an\nequilibrium shape under modest outer flows initially, the slow movement of the\ninner droplets might cause the contact of the outer and inner interface, and\neventually induces a breakup of the particle. Thus, appropriate outer flows and\ninternal structures of multiple emulsions might provide a possibility to\nexecute the control release through hydrodynamics.",
        "positive": "Dislocation Geometry in the TGB-A Phase: Linear Theory: We demonstrate that an arbitrary system of screw dislocations in a smectic-A\nliquid crystal may be consistently treated within harmonic elasticity theory,\nprovided that the angles between dislocations are sufficiently small. Using\nthis theory, we calculate the ground state configuration of the TGB-A phase. We\nobtain an estimate of the twist-grain-boundary spacing and screw dislocation\nspacing in a boundary in terms of the macroscopic parameters, in reasonable\nagreement with experimental results."
    },
    {
        "anchor": "Liquid relaxation: A new Parodi-like relation for nematic liquid\n  crystals: We put forward a hydrodynamic theory of nematic liquid crystals that includes\nboth anisotropic elasticity and dynamic relaxation. Liquid remodeling is\nencompassed through a continuous update of the shear-stress free configuration.\nThe low-frequency limit of the dynamical theory reproduces the classical\nEricksen-Leslie theory, but it predicts two independent identities between the\nsix Leslie viscosity coefficients. One replicates Parodi's relation, while the\nother-which involves five Leslie viscosities in a nonlinear way-is new. We\ndiscuss its significance, and we test its validity against evidence from\nphysical experiments, independent theoretical predictions, and\nmolecular-dynamics simulations.",
        "positive": "Bacterial biofilms use chiral branches to escape crowded environments by\n  tracking oxygen gradient: Bacterial biofilms collectively develop distinct and ordered structures,\nincluding fibers, bundles, and branches. Often, it is unclear how these\nstructural motifs convey specific advantages to bacterial strains under\nchallenging conditions. In oxygen-limited environments, dense bacterial\naggregates generally deplete oxygen, which leads to arrest of bacterial growth.\nHowever, we observed that biofilm-forming Bacillus subtilis could use branching\npatterns to escape from these crowded regions by tracking the oxygen gradient.\nThe process depends on the chain-forming ability of the biofilm. As a result of\ncollective branching triggered by bending and mechanical buckling, bacteria can\nextend from the oxygen-depleted biofilm core to the oxygen available periphery.\nRemarkably, these bacterial branches are strongly chiral and curve in a\nclockwise direction. Our analysis revealed that the surface friction and axial\nrotation of the twisting cell wall break left-right symmetry on solid surfaces\nand drive chiral bending of bacterial chains. We further observed that the\nchirality of individual branches could propagate across a large scale and shape\nthe macroscopic morphology of the colony under a limited spatiotemporal growth\nprofile. Taken together, our results provide new insights into how simple\nphysical interactions lead to bacterial collaboration and promote the survival\nof biofilm-forming strains in challenging environments."
    },
    {
        "anchor": "Jammed frictional tetrahedra are hyperstatic: We prepare packings of frictional tetrahedra with volume fractions {\\phi}\nranging from 0.469 to 0.622 using three different experimental protocols under\nisobaric conditions. Analysis via X-ray micro-tomography reveals that the\ncontact number Z grows with {\\phi}, but does depend on the preparation\nprotocol. While there exist four different types of contacts in tetrahedra\npackings, our analysis shows that the edge-to-face contacts contribute about\n50% of the total increase in Z. The number of constraints per particle C\nincreases also with {\\phi} and even the loosest packings are strongly\nhyperstatic i.e. mechanically over-determined with C approximately twice the\ndegrees of freedom each particle possesses.",
        "positive": "Fracture and fatigue of entangled and unentangled polymer networks: Entanglement of polymer chains is ubiquitous in elastomers, gels, and\nbiological tissues. While the effects of chain entanglement on elasticity and\nviscoelasticity of polymer networks have been intensively studied, it remains\nelusive how chain entanglement affects fracture and fatigue of polymer\nnetworks. In this paper, using polyacrylamide hydrogels as a model material, we\nsystematically compare fracture toughness and fatigue threshold of polymer\nnetworks with various levels of chain entanglement. We find that the fracture\ntoughness and fatigue threshold of an unentangled polymer network are almost\nthe same, although the unentangled polymer network still contains non-ideal\nfeatures including topological defects (i.e., dangling chains and cyclic loops)\nand structural heterogeneity (i.e., non-uniform chain lengths and non-uniform\nfunctionalities). In contrast, the fracture toughness of an entangled polymer\nnetwork can be over ten times (up to 16 times) higher than its fatigue\nthreshold, indicating substantial toughness enhancement due to chain\nentanglement. Different from the conventional toughness enhancement due to bulk\ndissipation of polymer networks, the toughness enhancement by chain\nentanglement requires low stress-stretch hysteresis (<10%) of the bulk\nentangled polymer networks. We attribute the toughness enhancement in entangled\npolymer networks to a new dissipation mechanism, near-crack dissipation, which\nis possibly induced by pull-out of chains and delocalized damage of chains\naround the crack tip."
    },
    {
        "anchor": "Persistent anti-correlations in Brownian dynamics simulations of dense\n  colloidal suspensions revealed by noise suppression: Transport properties of a hard-sphere colloidal fluid are investigated by\nBrownian dynamics simulations. We implement a novel algorithm for the\ntime-dependent velocity-autocorrelation function (VACF) essentially eliminating\nthe noise of the bare random motion. The measured VACF reveals persistent\nanti-correlations manifested by a negative algebraic power-law tail $t^{-5/2}$\nat all densities. At small packing fractions, the simulations fully agree with\nthe analytic low-density prediction, yet the amplitude of the tail becomes\ndramatically suppressed as the packing fraction is increased. The mode-coupling\ntheory of the glass transition provides a qualitative explanation for the\nstrong variation in terms of the static compressibility as well as the slowing\ndown of the structural relaxation.",
        "positive": "Tiling a tubule: How increasing complexity improves the yield of\n  self-limited assembly: The ability to design and synthesize ever more complicated colloidal\nparticles opens the possibility of self-assembling a zoo of complex structures,\nincluding those with one or more self-limited length scales. An undesirable\nfeature of systems with self-limited length scales is that thermal fluctuations\ncan lead to the assembly of nearby, off-target states. We investigate\nstrategies for limiting off-target assembly by using multiple types of\nsubunits. Using simulations and energetics calculations, we explore this\nconcept by considering the assembly of tubules built from triangular subunits\nthat bind edge to edge. While in principle, a single type of triangle can\nassemble into tubules with a monodisperse width distribution, in practice, the\nfinite bending rigidity of the binding sites leads to the formation of\noff-target structures. To increase the assembly specificity, we introduce\ntiling rules for assembling tubules from multiple species of triangles. We show\nthat the selectivity of the target structure can be dramatically improved by\nusing multiple species of subunits, and provide a prescription for choosing the\nminimum number of subunit species required for near-perfect yield. Our approach\nof increasing the system's complexity to reduce the accessibility of\nneighboring structures should be generalizable to other systems beyond the\nself-assembly of tubules."
    },
    {
        "anchor": "Enhanced diffusivity in microscopically reversible active matter: Physics of self-propelled objects at the nanoscale is a rapidly developing\nresearch field where recent experiments focused on motion of individual\ncatalytic enzymes. Contrary to the experimental advancements, theoretical\nunderstanding of possible self-propulsion mechanisms at these scales is\nlimited. A particularly puzzling question concerns origins of reportedly high\ndiffusivities of the individual enzymes. Here we start with the fundamental\nprinciple of microscopic reversibility (MR) of chemical reactions powering the\nself-propulsion and demonstrate that MR can lead to increase of the particle\nmobility and of short- and long-time diffusion coefficients as compared to\ndynamics where MR is neglected. Moreover, the diffusion coefficients can be\nenhanced by a constant external force. We propose a way to use these effects in\nexperimental investigations of active propulsion mechanisms at the nanoscale.\nOur results can shed new light on interpretation of the measured diffusivities\nand help to test and to evaluate relevance of MR for the active motion of\nindividual nanoswimmers.",
        "positive": "A Taxonomy of Snow Crystal Growth Behaviors: 2. Quantifying the Nakaya\n  Diagram: This paper presents a matrix of 206 snow crystal growth observations as a\nfunction of temperature and water vapor supersaturation in air, each\nillustrating the morphology and size of a crystal forming on the tip of an\nisolated c-axis ice needle after a known growth time. Because each complex\nstructure emerged from a simple, well-defined seed crystal under known\nenvironmental conditions, this data set is well suited for making comparisons\nwith three-dimensional computational models. These observations thus provide a\nneeded extension of the well-known Nakaya diagram, as they allow a quantitative\nevaluation of model predictions over a broad range of growth conditions. I also\nbriefly discuss computational methods along with an initial model of the most\nrelevant microphysical processes governing snow crystal growth. My overarching\ngoal with this new data set is to facilitate the development of quantitative\ncomputational growth models that can eventually reproduce the remarkable\ndiversity of morphological structures seen in snow crystal formation."
    },
    {
        "anchor": "Forced imbibition in porous media: a fourfold scenario: We establish a comprehensive description of the patterns formed when a\nwetting liquid displaces a viscous fluid confined in a porous medium. Building\non model microfluidic experiments, we evidence four imbibition scenarios all\nyielding different large-scale morphologies. Combining high-resolution imaging\nand confocal microscopy, we show that they originate from two\nliquid-entrainment transitions and a Rayleigh-Plateau instability at the pore\nscale. Finally, we demonstrate and explain the long-time coarsening of the\nresulting patterns.",
        "positive": "Membrane shape deformation induced by curvature-inducing proteins\n  consisting of chiral crescent binding and intrinsically disordered domains: Curvature-inducing proteins containing a Bin/Amphiphysin/Rvs domain often\nhave intrinsically disordered domains. Recent experiments have shown that these\ndisordered chains enhance curvature sensing and generation. Here, we report on\nthe modification of protein-membrane interactions by disordered chains using\nmeshless membrane simulations. The protein and bound membrane are modeled\ntogether as a chiral crescent protein rod with two excluded-volume chains. As\nthe chain length increases, the repulsion between them reduces the cluster size\nof the proteins. It induces spindle-shaped vesicles and a transition between\narc-shaped and circular protein assemblies in a disk-shaped vesicle. For flat\nmembranes, an intermediate chain length induces many tubules owing to the\nrepulsion between the protein assemblies, whereas longer chains promote\nperpendicular elongation of tubules. Moreover, protein rods with zero rod\ncurvature and sufficiently long chains stabilize the spherical buds. For\nproteins with a negative rod curvature, an intermediate chain length induces a\nrugged membrane with branched protein assemblies, whereas longer chains induce\nthe formation of tubules with periodic concave-ring structures."
    },
    {
        "anchor": "A thermodynamic framework for non-isothermal phenomenological models of\n  isotropic Mullins effect: The Mullins effect is a common name for a family of intriguing inelastic\nresponses of various solid materials, in particular filled rubbers. Given the\nimportance of the Mullins effect, there have been many attempts to develop\nmathematical models describing the effect. However, most of available models\nfocus exclusively on the mechanical response, and are restricted to the\nidealised isothermal setting. We lift the restriction to isothermal processes,\nand we propose a full thermodynamic framework for a class of phenomenological\nmodels of the Mullins effect. In particular, we identify energy storage\nmechanisms (Helmholtz free energy) and entropy production mechanisms that on\nthe level of stress--strain relation lead to the idealised Mullins effect or to\nthe Mullins effect with permanent strain. The models constructed within the\nproposed framework can be used in the modelling of fully coupled\nthermo-mechanical processes, and the models are guaranteed to be consistent\nwith the laws of thermodynamics.",
        "positive": "The desalting/salting pathway: a route to form metastable aggre-gates\n  with tuneable morphologies and lifetimes: We investigate the formation/re-dissociation mechanisms of hybrid complexes\nmade from negatively charged PAA2k coated {\\gamma}-Fe2O3 nanoparticles (NP) and\npositively charged polycations (PDADMAC) in aqueous solution in the regime of\nvery high ionic strength (I). When the building blocks are mixed at large ionic\nstrength (1M NH4Cl), the electrostatic interaction is screened and complexation\ndoes not occur. If the ionic strength is then lowered down to a targeted ionic\nstrength Itarget, there is a critical threshold Ic = 0.62 M at which\ncomplexation occurs, that is independent on the charge ratio Z and the pathway\nused to reduce salinity (drop-by-drop mixing or fast mixing). If salt is added\nback up to 1M, the transition is not reversible and persistent\nout-of-equilibrium aggregates are formed. The lifetimes of such aggregates\ndepends on Itarget: the closer Itarget to Ic is, the more difficult it is to\ndissolve the aggregates. Such peculiar behavior is driven by the inner\nstructure of the complexes that are formed after desalting. When Itarget is far\nbelow Ic, strong electrostatic interactions induce the formation of dense,\ncompact and frozen aggregates. Such aggregates can only poorly reorganize\nfurther on with time, which makes their dissolution upon resalting almost\nreversible. Conversely, when Itarget is close to Ic more open aggregates are\nformed due to weaker electrostatic interactions upon desalting. System can thus\nrearrange with time to lower its free energy and reach more stable\nout-of-equilibrium states which are very difficult to dissociate back upon\nresalting, even at very high ionic strength."
    },
    {
        "anchor": "Critical condition for electrowetting-induced detachment of a droplet\n  from a curved surface: Based on energy conservation, we derive a critical condition theoretically\nfor electrowettinginduced droplet detachment from a hydrophobic curved surface.\nPhase diagrams are constructed in terms of droplet volume, viscosity, Ohnesorge\nnumber, friction coefficient at contact line, surface curvature, surface\nwettability and electrowetting number. The deduced critical condition offers a\ngeneral and quantitative prediction on when the detachment occurs, a criterion\nenabling us to gain more insights into how to accurately manipulate the\nelectrowetting-induced detachment of an aqueous droplet on a curved surface.\nThe results obtained in this paper also imply that the detachable regimes of\nthe phase diagrams can be enlarged through increasing droplet volume and\nsurface curvature, and reducing liquid viscosity, friction coefficient,\nOhnesorge number and wettability of substrates.",
        "positive": "Unstable fronts and stable \"critters\" formed by microrollers: Condensation of objects into stable clusters occurs naturally in equilibrium\nand driven systems. It is commonly held that potential interactions, depletion\nforces, or sensing are the only mechanisms which can create long-lived compact\nstructures. Here we show that persistent motile structures can form\nspontaneously from hydrodynamic interactions alone with no sensing or potential\ninteractions. We study this structure formation in a system of colloidal\nrollers suspended and translating above a floor, using both experiments and\nlarge-scale 3D simulations. In this system, clusters originate from a\npreviously unreported fingering instability, where fingers pinch off from an\nunstable front to form autonomous \"critters\", whose size is selected by the\nheight of the particles above the floor. These critters are a stable state of\nthe system, move much faster than individual particles, and quickly respond to\na changing drive. With speed and direction set by a rotating magnetic field,\nthese active structures offer interesting possibilities for guided transport,\nflow generation, and mixing at the microscale."
    },
    {
        "anchor": "Dynamical force measurements for contacting soft surfaces upon steady\n  sliding: Fixed-depth tribology: The tribology between surfaces can have a profound impact on the response of\na mechanical system, such as how granular particles are driven to flow. In this\nwork, we perform experiments that time-resolve the tangential and normal\ncomponents of the force between two semi-cylindrical PDMS\n(polydimethylsiloxane) samples immersed in fluid, as they slide against each\nother in a range of controlled speeds. The time-averaged friction force shows a\nnon-monotonic dependence on the sliding speed over four decades, which is\nconsistent to the paradigmatic Stribeck diagram and three dynamical regimes\nassociated with it. Our specially designed fixed-depth setup allows us to study\nthe fluctuation of force that exhibits strong stick-slip patterns in one of the\nregimes. Data from repetitive experiments reveal that both the \"onset speed\"\nfor the stick-slip patterns and its spatial location along the sample change\ngradually during the course of our experiments, indicating changes on the\nsample surfaces. In addition, we conduct counterpart experiments by using\nspherical samples rubbing against each other, to make a direct connection of\nthe inter-particle tribology to the granular flow reported in our previous work\n[Phys. Rev. Lett. 126,128001 (2021)].",
        "positive": "Narrow escape in composite domains forming heterogeneous networks: Cellular networks are often composed of thin tubules connecting much larger\nnode compartments. These structures serve for active or diffusion transport of\nproteins. Examples are glial networks in the brain, the endoplasmic reticulum\nin cells or dendritic spines located on dendrites. In this latter case, a large\nball forming the head is connected by a narrow passage. In all cases, how the\ntransport of molecules, ions or proteins is regulated determines the time scale\nof chemical reactions or signal transduction. In the present study, based on\nmodeling diffusion in three dimensions, we compute the mean time for a Brownian\nparticle to reach a narrow target inside such a composite network made of\ntubules connected to spherical nodes. We derive asymptotic formulas by solving\na mixed Neumann-Dirichlet boundary value problem with small Dirichlet part. We\nfirst consider the case of a network domain organized in a 2-D lattice\nstructure that consists of spherical ball compartments connected via narrow\ncylindrical passages. When there is a single target we derive a matrix equation\nfor each Mean First Passage Time (MFPT) averaged over each spherical\ncompartment. We then consider a composite domain consisting of a spherical\nhead-like domain connected to a large cylinder via a narrow cylindrical neck.\nFor Brownian particles starting within the narrow neck, we derive formulas for\nthe MFPT to reach a target on the spherical head. When diffusing particles can\nbe absorbed upon hitting additional absorbing boundaries of the large cylinder,\nwe compute the probability and conditional MFPT to reach a target. We compare\nthese formulas with numerical solutions of the mixed boundary value problem and\nwith Brownian simulations. To conclude, the present analysis reveals that the\nmean arrival time, driven by diffusion in heterogeneous networks, is controlled\nby the target and narrow passage sizes."
    },
    {
        "anchor": "Brillouin zone labelling for quasicrystals: We propose a scheme to determine the energy-band dispersion of quasicrystals\nwhich does not require any periodic approximation and which directly provides\nthe correct structure of the extended Brillouin zones. In the gap labelling\nviewpoint, this allow to transpose the measure of the integrated\ndensity-of-states to the measure of the effective Brillouin-zone areas that are\nuniquely determined by the position of the Bragg peaks. Moreover we show that\nthe Bragg vectors can be determined by the stability analysis of the law of\nrecurrence used to generate the quasicrystal. Our analysis of the gap labelling\nin the quasi-momentum space opens the way to an experimental proof of the gap\nlabelling itself within the framework of an optics experiment, polaritons, or\nwith ultracold atoms.",
        "positive": "Supporting Material for: Capillary-like Fluctuations of a Solid-Liquid\n  Interface in a Non-Cohesive Granular System: In this supplementary paper we present some details on the solid-liquid\ninterface detection, the deduction of the non-equilibrium free energy, the\nanalysis of the granular temperature and energy per mode, a validation of the\nsmall slope approximation, a description of the Langevin dynamics, and the\nerror analysis."
    },
    {
        "anchor": "Active cholesterics: odder than odd elasticity: In equilibrium liquid crystals, chirality leads to a variety of spectacular\nthree-dimensional structures, but chiral and achiral phases with the same\nbroken continuous symmetries have identical long-time, large-scale dynamics. In\nthis paper, we demonstrate that chirality qualitatively modifies the dynamics\nof layered liquid crystals in active systems in both two and three dimensions\ndue to an active \"odder\" elasticity. In three dimensions, we demonstrate that\nthe hydrodynamics of active cholesterics differs fundamentally from smectic-A\nliquid crystals, unlike their equilibrium counterpart. This distinction can be\nused to engineer a columnar array of vortices, with anti-ferromagnetic\nvorticity alignment, that can be switched on and off by external strain. A\ntwo-dimensional chiral layered state -- an array of lines on an incompressible,\nfree-standing film of chiral active fluid with a preferred normal direction --\nis generically unstable. However, this instability can be tuned in easily\nrealisable experimental settings, when the film is either on a substrate or in\nan ambient fluid.",
        "positive": "Self-adaptation of Pseudomonas fluorescens biofilms to hydrodynamic\n  stress: In some conditions, bacteria self-organise into biofilms, supracellular\nstructures made of a self-produced embedding matrix, mainly composed on\npolysaccharides, DNA, proteins and lipids. It is known that bacteria change\ntheir colony/matrix ratio in the presence of external stimuli such as\nhydrodynamic stress. However, little is still known about the molecular\nmechanisms driving this self-adaptation. In this work, we monitor structural\nfeatures of Pseudomonas fluorescens biofilms grown with and without\nhydrodynamic stress. Our measurements show that the hydrodynamic stress\nconcomitantly increases the cell density population and the matrix production.\nAt short growth timescales, the matrix mediates a weak cell-cell attractive\ninteraction due to the depletion forces originated by the polymer constituents.\nUsing a population dynamics model, we conclude that hydrodynamic stress causes\na faster diffusion of nutrients and a higher incorporation of planktonic\nbacteria to the already formed microcolonies. This results in the formation of\nmore mechanically stable biofilms due to an increase of the number of\ncrosslinks, as shown by computer simulations. The mechanical stability also\nlies on a change in the chemical compositions of the matrix, which becomes\nenriched in carbohydrates, known to display adhering properties. Overall, we\ndemonstrate that bacteria are capable of self-adapting to hostile hydrodynamic\nstress by tailoring the biofilm chemical composition, thus affecting both the\nmesoscale structure of the matrix and its viscoelastic properties that\nultimately regulate the bacteria-polymer interactions."
    },
    {
        "anchor": "The mean-field theory for attraction between like-charged macromolecules: A mean-field theory based on Gibbs-Bogoliubov inequality is constructed to\nstudy the interactions between two like-charged polyions. It is shown that\ncontrary to the previously established paradigm, a properly constructed\nmean-field theory can quantitatively account for the attractive interactions\nbetween two like-charged rods.",
        "positive": "Shaken and stirred: Random organization reduces viscosity and\n  dissipation in granular suspensions: The viscosity of suspensions of large ($\\geq10{\\mu m}$) particles diverges at\nhigh solid fractions due to proliferation of frictional particle contacts.\nReducing friction, to allow or improve flowability, is usually achieved by\ntuning the composition, either changing particle sizes and shapes or by adding\nlubricating molecules. We present numerical simulations that demonstrate a\ncomplementary approach whereby the viscosity divergence is shifted by driven\nflow tuning, using superimposed shear oscillations in various configurations to\nfacilitate a primary flow. The oscillations drive the suspension towards an\nout-of-equilibrium, absorbing state phase transition, where frictional particle\ncontacts that dominate the viscosity are reduced in a self-organizing manner.\nThe method can allow otherwise jammed states to flow; even for unjammed states,\nit can substantially decrease the energy dissipated per unit strain. This\ncreates a practicable route to flow enhancement across a broad range of\nsuspensions where compositional tuning is undesirable or problematic."
    },
    {
        "anchor": "Self-organization of primitive metabolic cycles due to non-reciprocal\n  interactions: We study analytically and numerically a model metabolic cycle composed of an\narbitrary number of species of catalytically active particles. Each species\nconverts a substrate into a product, the latter being used as the substrate by\nthe next species in the cycle. Through a combination of catalytic activity and\nchemotactic mobility, the active particles develop effective non-reciprocal\ninteractions with particles belonging to neighbouring species in the cycle. We\nfind that such model metabolic cycles are able to self-organize through a\nmacroscopic instability, with a strong dependence on the number of species they\nincorporate. The parity of that number has a key influence: cycles containing\nan even number of species are able to minimize repulsion between their\ncomponent particles by aggregating all even-numbered species in one cluster,\nand all odd-numbered species in another. Such a grouping is not possible if the\ncycle contains an odd number of species, which can lead to oscillatory steady\nstates in the case of chasing interactions.",
        "positive": "Phase diagram of selectively cross-linked block copolymers shows\n  chemically microstructured gel: We study analytically the intricate phase behavior of cross-linked $AB$\ndiblock copolymer melts, which can undergo two main phase transitions due to\nquenched random constraints: Gelation, i.e., spatially random localization of\npolymers forming a system-spanning cluster, is driven by increasing the number\nparameter $\\mu$ of irreversible, type-selective cross-links between random\npairs of $A$ blocks. Self-assembly into a periodic pattern of $A$/$B$-rich\nmicrodomains (microphase separation) is controlled by the $AB$ incompatibility\n$\\chi$ inversely proportional to temperature. Our model aims to capture the\nsystem's essential microscopic features, including an ensemble of random\nnetworks that reflects spatial correlations at the instant of cross-linking. We\nidentify suitable order parameters and derive a free-energy functional in the\nspirit of Landau theory that allows us to trace a phase diagram in the plane of\n$\\mu$ and $\\chi$. Selective cross-links promote microphase separation at higher\ncritical temperatures than in uncross-linked diblock copolymer melts.\nMicrophase separation in the liquid state facilitates gelation, giving rise to\na novel gel state whose chemical composition density mirrors the periodic $AB$\npattern."
    },
    {
        "anchor": "Linear Response Theory of Scale-Dependent Viscoelasticity for Overdamped\n  Brownian Particle Systems: We show the linear response theory of spatial-scale-dependent relaxation\nmoduli for overdamped Brownian particle systems. We employ the Irving-Kirkwood\nstress tensor field as the microscopic stress tensor field. We show that the\nscale-dependent relaxation modulus tensor, which characterizes the response of\nthe stress tensor field to the applied velocity gradient field, can be\nexpressed by using the correlation function of the Irving-Kirkwood stress\ntensor field. The spatial Fourier transform of the relaxation modulus tensor\ngives the wavenumber-dependent relaxation modulus. For isotropic and\nhomogeneous systems, the relaxation modulus tensor has only two independent\ncomponents. The transverse and longitudinal deformation modes give the\nwavenumber-dependent shear relaxation modulus and the wavenumber-dependent bulk\nrelaxation modulus. As simple examples, we derive the explicit expressions for\nthe relaxation moduli for two simple models the non-interacting Brownian\nparticles and the harmonic dumbbell model.",
        "positive": "Plectoneme tip bubbles: Coupled denaturation and writhing in supercoiled\n  DNA: Biological information is not only stored in the digital chemical sequence of\ndouble helical DNA, but is also encoded in the mechanical properties of the DNA\nstrands, which can influence biochemical processes involving its readout. For\nexample, loop formation in the Lac operon can regulate the expression of key\ngenes, and DNA supercoiling is closely correlated to rhythmic circardian gene\nexpression in cyanobacteria. Supercoiling is also important for large scale\norganisation of the genome in both eukaryotic and prokaryotic cells. DNA can\nrespond to torsional stress by writhing to form looped structures called\nplectonemes, thus transferring energy stored as twist into energy stored in\nbending. Denaturation bubbles can also relax torsional stress, with the\nenthalpic cost of breaking bonds being compensated by their ability to absorb\nundertwist. Here we predict a novel regime where bubbles form at the tips of\nplectonemes, and study its properties using coarse-grained simulations. These\ntip bubbles can occur for both positive and negative supercoiling and greatly\nreduce plectoneme diffusion by a pinning mechanism. They can cause plectonemes\nto preferentially localise to AT rich regions, because bubbles more easily form\nthere. The tip-bubble regime occurs for supercoiling densities and forces that\nare typically encountered for DNA in vivo, and may be exploited for biological\ncontrol of genomic processes."
    },
    {
        "anchor": "A neural network potential with self-trained atomic fingerprints: a test\n  with the mW water potential: We present a neural network (NN) potential based on a new set of atomic\nfingerprints built upon two- and three-body contributions that probe distances\nand local orientational order respectively. Compared to existing NN potentials,\nthe atomic fingerprints depend on a small set of tuneable parameters which are\ntrained together with the neural network weights. To tackle the simultaneous\ntraining of the atomic fingerprint parameters and neural network weights we\nadopt an annealing protocol that progressively cycles the learning rate,\nsignificantly improving the accuracy of the NN potential. We test the\nperformance of the network potential against the mW model of water, which is a\nclassical three-body potential that well captures the anomalies of the liquid\nphase. Trained on just three state points, the NN potential is able to\nreproduce the mW model in a very wide range of densities and temperatures, from\nnegative pressures to several GPa, capturing the transition from an open random\ntetrahedral network to a dense interpenetrated network. The NN potential also\nreproduces very well properties for which it was not explicitly trained, such\nas dynamical properties and the structure of the stable crystalline phases of\nmW.",
        "positive": "Random walk with barriers: Diffusion restricted by permeable membranes: Restrictions to molecular motion by barriers (membranes) are ubiquitous in\nbiological tissues, porous media and composite materials. A major challenge is\nto characterize the microstructure of a material or an organism\nnondestructively using a bulk transport measurement. Here we demonstrate how\nthe long-range structural correlations introduced by permeable membranes give\nrise to distinct features of transport. We consider Brownian motion restricted\nby randomly placed and oriented permeable membranes and focus on the\ndisorder-averaged diffusion propagator using a scattering approach. The\nrenormalization group solution reveals a scaling behavior of the diffusion\ncoefficient for large times, with a characteristically slow inverse square root\ntime dependence. The predicted time dependence of the diffusion coefficient\nagrees well with Monte Carlo simulations in two dimensions. Our results can be\nused to identify permeable membranes as restrictions to transport in disordered\nmaterials and in biological tissues, and to quantify their permeability and\nsurface area."
    },
    {
        "anchor": "Orientational ordering of lamellar structures on closed surfaces: Self-assembly of particles with short-range attraction and long-range\nrepulsion (SALR) interactions on a flat and on a spherical surface is compared.\nMolecular dynamics (MD) simulations are performed for the two systems having\nthe same area and the density optimal for formation of stripes of particles.\nStructural characteristics, e.g. a cluster size distribution, a number of\ndefects and an orientational order parameter (OP), as well as the specific\nheat, are obtained for a range of temperature. In both cases, the cluster size\ndistribution becomes bimodal and elongated clusters appear at the temperature\ncorresponding to the maximum of the specific heat. When the temperature\ndecreases, orientational ordering of the stripes takes place, and the number of\nparticles per cluster or stripe increases in both cases. However, only on the\nflat surface the specific heat has another maximum at the temperature\ncorresponding to a rapid change of the OP. On the sphere, the crossover between\nthe isotropic and anisotropic structures occurs in a much broader temperature\ninterval, the orientational order is weaker, and occurs at significantly lower\ntemperature. At low temperature the stripes on the sphere form spirals, and the\ndefects resemble defects in the nematic phase of rods adsorbed at a sphere.",
        "positive": "Glassy dynamics, spinodal fluctuations, and the kinetic limit of\n  hard-rod nucleation: Using simulations we identify three dynamic regimes in supersaturated\nisotropic fluid states of short hard rods: (i) for moderate supersaturations we\nobserve nucleation of multi-layered crystalline clusters; (ii) at higher\nsupersaturation, we find nucleation of small crystallites which arrange into\nlong-lived locally favored structures that get kinetically arrested, while\n(iii) at even higher supersaturation the dynamic arrest is due to the\nconventional cage-trapping glass transition. For longer rods we find that the\nformation of the (stable) smectic phase out of a supersaturated isotropic state\nis strongly suppressed by an isotropic-nematic spinodal instability that causes\nhuge spinodal-like orientation fluctuations with nematic clusters diverging in\nsize. Our results show that glassy dynamics and spinodal instabilities set\nkinetic limits to nucleation in a highly supersaturated hard-rod fluids."
    },
    {
        "anchor": "Phase separation of active Brownian particles on curved surfaces: The effect of curvature on an ensemble of repulsive active Brownian particles\n(ABPs) moving on a spherical surface is studied. Surface curvature strongly\naffects the dynamics of ABPs, as it introduces a new time scale $\\tau=R/v_0$,\nwith curvature radius $R$ and propulsion velocity $v_0$, in addition to the\nrotational diffusion time $\\tau_r$. This implies that motility-induced phase\nseparation (MIPS) disappears for small $R$. Furthermore, it causes a narrowing\nof the MIPS regime in the phase diagram of P{\\'e}clet number $\\text{Pe}$ and\nparticle area fraction $\\phi$. Also, the phase-separation boundary at low\n$\\phi$ attains a turning point at small $R$, allowing for the possibility of a\nreentrant behavior. These results characterize the effect of curvature on ABP\ndynamics and MIPS, and will help to better understand the preferred occupation\nof certain niches by bacterial colonies in porous media.",
        "positive": "Clogging and avalanches in quasi-two-dimensional emulsion hopper flow: We experimentally and computationally study the flow of a\nquasi-two-dimensional emulsion through a constricting hopper shape. Our area\nfractions are above jamming such that the droplets are always in contact with\none another and are in many cases highly deformed. At the lowest flow rates,\nthe droplets exit the hopper via intermittent avalanches. At the highest flow\nrates, the droplets exit continuously. The transition between these two types\nof behaviors is a fairly smooth function of the mean strain rate. The\navalanches are characterized by a power law distribution of the time interval\nbetween droplets exiting the hopper, with long intervals between the\navalanches. Our computational studies reproduce the experimental observations\nby adding a flexible compliance to the system. The compliance results in\ncontinuous flow at high flow rates, and allows the system to clog at low flow\nrates leading to avalanches. The computational results suggest that the\ninterplay of the flow rate and compliance controls the presence or absence of\nthe avalanches."
    },
    {
        "anchor": "Sounds and hydrodynamics of polar active fluids: Spontaneously flowing liquids have been successfully engineered from a\nvariety of biological and synthetic self-propelled units. Together with their\norientational order, wave propagation in such active fluids have remained a\nsubject of intense theoretical studies. However, the experimental observation\nof this phenomenon has remained elusive. Here, we establish and exploit the\npropagation of sound waves in colloidal active materials with broken rotational\nsymmetry. We demonstrate that two mixed modes coupling density and velocity\nfluctuations propagate along all directions in colloidal-roller fluids. We then\nshow how the six materials constants defining the linear hydrodynamics of these\nactive liquids can be measured from their spontaneous fluctuation spectrum,\nwhile being out of reach of conventional rheological methods. This active-sound\nspectroscopy is not specific to synthetic active materials and could provide a\nquantitative hydrodynamic description of herds, flocks and swarms from\ninspection of their large-scale fluctuations",
        "positive": "Phase behaviour of two-component bottle-brush polymers with flexible\n  backbones under poor solvent conditions: The phase behaviour of two-component bottle-brush polymers with fully\nflexible backbones under poor solvent conditions is studied via\nmolecular-dynamics simulations, using a coarse-grained bead-spring model and\nside chains of up to $N=40$ effective monomers. We consider a symmetric model\nwhere side chains of type A and B are grafted alternately onto a flexible\nbackbone. The aim of this study to explore the phase behaviour of two-component\nbottle-brushes depending on parameters, such as as the grafting density\n$\\sigma$, the backbone length $N_b$, the side-chain length $N$, and the\ntemperature $T$. Based on a cluster analysis, we identify for our range of\nparameters the regimes of fully phase separated systems, i.e., A-type side\nchains form one cluster and B-type chains another, while the interface that\nseparates these two clusters contains the backbone monomers. We find that\npearl-necklace or Janus-like structures, which normally occur for bottle-brush\npolymers with rigid backbones under poor solvent conditions, are fully\nattributed to the backbone rigidity, and, therefore, such structures are\nunlikely in the case of bottle brushes with fully flexible backbones. Also, a\ncomparative discussion with earlier work on the phase behaviour of\nsingle-component bottle-brush polymers with flexible backbones is performed."
    },
    {
        "anchor": "Extrinsic Curvature, Geometric Optics, and Lamellar Order on Curved\n  Substrates: When thermal energies are weak, two dimensional lamellar structures confined\non a curved substrate display complex patterns arising from the competition\nbetween layer bending and compression in the presence of geometric constraints.\nWe present broad design principles to engineer the geometry of the underlying\nsubstrate so that a desired lamellar pattern can be obtained by self-assembly.\nTwo distinct physical effects are identified as key factors that contribute to\nthe interaction between the shape of the underlying surface and the resulting\nlamellar morphology. The first is a local ordering field for the direction of\neach individual layer which tends to minimize its curvature with respect to the\nthree-dimensional embedding. The second is a non-local effect controlled by the\nintrinsic geometry of the surface that forces the normals to the (nearly\nincompressible) layers to lie on geodesics, leading to caustic formation as in\noptics. As a result, different surface morphologies with predominantly positive\nor negative Gaussian curvature can act as converging or diverging lenses\nrespectively. By combining these ingredients, as one would with different\noptical elements, complex lamellar morphologies can be obtained. This smectic\noptometry enables the manipulation of lamellar configurations for the design of\nnovel materials.",
        "positive": "A model for effective interactions in binary colloidal systems of soft\n  particles: While the density functional theory with integral equations techniques are\nvery efficient tools in numerical analysis of complex fluids, an analytical\ninsight into the phenomenon of effective interactions is still limited. In this\npaper we propose a theory of binary systems which results in a relatively\nsimple analytical expression combining arbitrary microscopic potentials into\nthe effective interaction. The derivation is based on translating many particle\nHamiltonian including particle-depletant and depletant-depletant interactions\ninto the occupation field language. Such transformation turns the partition\nfunction into multiple Gaussian integrals, regardless of what microscopic\npotentials are chosen. In result, we calculate the effective Hamiltonian and\ndiscuss when our formula is a dominant contribution to the effective\ninteractions. Our theory allows us to analytically reproduce several important\ncharacteristics of systems under scrutiny. In particular, we analyze the\neffective attraction as a demixing factor in the binary systems of Gaussian\nparticles, effective interactions in the binary mixtures of Yukawa particles\nand the system of particles consisting of both repulsive core and\nattractive/repulsive Yukawa interaction tail, for which we reproduce the\n'attraction-through-repulsion' and 'repulsion-through-attraction' effects."
    },
    {
        "anchor": "Morphogenesis through elastic phase separation in a pneumatic surface: We report a phenomenon of phase separation that relates in many aspects to\nYves Couder's work: an inflatable architectured elastomer plate, expected to\nexpand homogeneously in its plane, buckles instead widely out-of-plane into\nvery complex shape when internal pressure is applied. We show that this\nmorphogenetic pattern formation is due to a two-dimensional elastic phase\nseparation, which induces incompatible patchy non-Euclidean reference metric.",
        "positive": "Multiple time scales hidden in heterogeneous dynamics of glass-forming\n  liquids: A multi-time probing of density fluctuations is introduced to investigate\nhidden time scales of heterogeneous dynamics in glass-forming liquids.\nMolecular dynamics simulations for simple glass-forming liquids are performed,\nand a three-time correlation function is numerically calculated for general\ntime intervals. It is demonstrated that the three-time correlation function is\nsensitive to the heterogeneous dynamics and that it reveals couplings of\ncorrelated motions over a wide range of time scales. Furthermore, the time\nscale of the heterogeneous dynamics $\\tau_{\\rm hetero}$ is determined by the\nchange in the second time interval in the three-time correlation function. The\npresent results show that the time scale of the heterogeneous dynamics\n$\\tau_{\\rm hetero}$ becomes larger than the $\\alpha$-relaxation time at low\ntemperatures and large wavelengths. We also find a dynamical scaling relation\nbetween the time scale $\\tau_{\\rm hetero}$ and the length scale $\\xi$ of\ndynamical heterogeneity as $\\tau_{\\rm hetero} \\sim \\xi^{z}$ with $z=3$."
    },
    {
        "anchor": "2D versus 3D Freezing of a Lennard-Jones Fluid in a Slit Pore: We present a computer simulation study of a (6,12)-Lennard-Jones fluid\nconfined to a slit pore, formed by two uniform planes. These interact via a\n(3,9)-Lennard-Jones potential with the fluid particles. When the fluid\napproaches the liquid-to-solid transition we first observe layering parallel to\nthe walls. In order to investigate the nature of the freezing transition, we\nperformed a detailed analysis of the bond-orientational order parameter in the\nlayers. Changing the distance between the slit wall, we studied howthe\nbehaviour changes from a quasi-2d crystallization without hysteresis and an\nintermediate hexatic phase to a standard 3d nucleation.",
        "positive": "Uniform phases in fluids of hard isosceles triangles: one component and\n  binary mixtures: We formulate the scaled particle theory for a general mixture of hard\nisosceles triangles and calculate different phase diagrams for the\none-component fluid and for certain binary mixtures. The fluid of hard\ntriangles exhibits a complex phase behavior: (i) the presence of a triatic\nphase with sixfold symmetry, (ii) the isotropic-uniaxial nematic transition is\nof first order for certain ranges of aspect ratios, and (iii) the one-component\nsystem exhibits nematic-nematic transitions ending in critical points. We found\nthe triatic phase to be stable not only for equilateral triangles but also for\ntriangles of similar aspect ratios. We focus the study of binary mixtures on\nthe case of symmetric mixtures: equal particle areas with aspect ratios\n($\\kappa_i$) symmetric with respect to the equilateral one:\n$\\kappa_1\\kappa_2=3$. For these mixtures we found, aside from first-order\nisotropic-nematic and nematic-nematic transitions (the latter ending in a\ncritical point): (i) A region of triatic phase stability even for mixtures made\nof particles that do not form this phase at the one-component limit, and (ii)\nthe presence of a Landau point at which two isotropic-nematic first-order\ntransitions and a nematic-nematic demixing transition coalesce. This phase\nbehavior is analog to that of a symmetric three-dimensional mixture of rods and\nplates."
    },
    {
        "anchor": "Wave vector dependence of the dynamics in supercooled metallic liquids: We present a detailed investigation of the wave vector dependence of\ncollective atomic motion in Au49Cu26.9Si16.3Ag5.5Pd2.3 and Pd42.5Cu27Ni9.5P21\nsupercooled liquids close to the glass transition temperature. Using x-ray\nphoton correlation spectroscopy in a precedent uncovered spatial range of only\nfew interatomic distances, we show that the microscopic structural relaxation\nprocess follows in phase the structure with a marked slowing down at the main\naverage inter-particle distance. This behavior is accompanied by dramatic\nchanges in the shape of the intermediate scattering functions which suggest the\npresence of large dynamical heterogeneities at length-scales corresponding to\nfew particle diameters. A ballistic-like mechanism of particle motion seems to\ngovern the structural relaxation of the two systems in the highly viscous\nphase, likely associated to hopping of caged particles in agreement with\ntheoretical studies.",
        "positive": "Influence of non-universal effects on dynamical scaling in driven\n  polymer translocation: We study the dynamics of driven polymer translocation using both molecular\ndynamics (MD) simulations and a theoretical model based on the non-equilibrium\ntension propagation on the {\\it cis} side subchain. We present theoretical and\nnumerical evidence that the non-universal behavior observed in experiments and\nsimulations are due to finite chain length effects that persist well beyond the\nrelevant experimental and simulation regimes. In particular, we consider the\ninfluence of the pore-polymer interactions and show that they give a major\ncontribution to the non-universal effects. In addition, we present comparisons\nbetween the theory and MD simulations for several quantities, showing extremely\ngood agreement in the relevant parameter regimes. Finally, we discuss the\npotential limitations of the present theories."
    },
    {
        "anchor": "Scaling theory for the jamming transition: We propose a scaling ansatz for the elastic energy of a system near the\ncritical jamming transition in terms of three relevant fields: the compressive\nstrain $\\Delta \\phi$ relative to the critical jammed state, the shear strain\n$\\epsilon$, and the inverse system size $1/N$. We also use $\\Delta Z$, the\nnumber of contacts relative to the minimum required at jamming, as an\nunderlying control parameter. Our scaling theory predicts new exponents,\nexponent equalities and scaling collapses for energy, pressure and shear stress\nthat we verify with numerical simulations of jammed packings of soft spheres.\nIt also yields new insight into why the shear and bulk moduli exhibit different\nscalings; the difference arises because the shear stress vanishes as\n$1/\\sqrt{N}$ while the pressure approaches a constant in the thermodynamic\nlimit. The success of the scaling ansatz implies that the jamming transition\nexhibits an emergent scale invariance, and that it should be possible to\ndevelop a renormalization-group theory for jamming.",
        "positive": "Experimental Confirmation of the Universal Law for the Vibrational\n  Density of States of Liquids: An analytical model describing the vibrational phonon density of states\n(VDOS) of liquids has long been elusive, mainly due to the difficulty in\ndealing with the imaginary modes dominant in the low-energy region, as\ndescribed by the instantaneous normal mode (INM) approach. Nevertheless,\nZaccone and Baggioli have recently developed such a model based on overdamped\nLangevin liquid dynamics. The model was proposed to be the universal law for\nthe vibrational density of states of liquids. Distinct from the Debye law,\ng({\\omega}) ~ {\\omega}2, for solids, the universal law for liquids reveals a\nlinear relationship, g({\\omega}) ~ {\\omega}, in the low-energy region. The\nuniversal law has been successfully verified with computer simulated VDOS for\nLennard-Jones liquids. We further confirm this universal law with experimental\nVDOS measured by inelastic neutron scattering on real liquid systems including\nwater, liquid metal, and polymer liquids. We have applied this model and\nextracted the effective relaxation rate for the short time dynamics for each\nliquid. The model has been further evaluated in the predication of the specific\nheat. The results have been compared with the existing experimental data as\nwell as with values obtained by different approaches."
    },
    {
        "anchor": "Controlled Buckling and Crumpling of Nanoparticle-Coated Droplets: We introduce a new experimental approach to study the structural transitions\nof large numbers of nanoparticle-coated droplets as their volume is reduced. We\nuse an emulsion system where the dispersed phase is slightly soluble in the\ncontinuous phase. By adding a fixed amount of unsaturated continuous phase, the\nvolume of the droplets can be controllably reduced, causing them to buckle or\ncrumple, thereby becoming nonspherical. The resultant morphologies depend both\non the extent of volume reduction and the average droplet size. The buckling\nand crumpling behavior implies that the droplet surfaces are solid.",
        "positive": "Dead or alive: Distinguishing active from passive particles using\n  supervised learning: A longstanding open question in the field of dense disordered matter is how\nprecisely structure and dynamics are related to each other. With the advent of\nmachine learning, it has become possible to agnostically predict the dynamic\npropensity of a particle in a dense liquid based on its local structural\nenvironment. Thus far, however, these machine-learning studies have focused\nalmost exclusively on simple liquids composed of passive particles. Here we\nconsider a mixture of both passive and active (i.e.\\ self-propelled) Brownian\nparticles, with the aim to identify the active particles from minimal local\nstructural information. We compare a state-of-the-art machine learning approach\nfor passive systems with a new method we develop based on Voronoi tessellation.\nBoth methods accurately identify the active particles based on their structural\nproperties at high activity and low concentrations of active particles. Our\nVoronoi method is, however, substantially faster to train and deploy because it\nrequires fewer, and easy to compute, input features. Notably, both become\nineffective when the activity is low, suggesting a fundamentally different\nstructural signature for dynamic propensity and non-equilibrium activity.\nUltimately, these efforts might also find relevance in the context of\nbiological active glasses such as confluent cell layers, where subtle changes\nin the microstructure can hint at pathological changes in cell dynamics."
    },
    {
        "anchor": "Effect of bond length fluctuations on crystal nucleation of hard bead\n  chains: We study the spontaneous nucleation and crystallization of linear and cyclic\nchains of flexibly connected hard spheres using extensive molecular dynamics\nsimulations. To this end, we present a novel event-driven molecular dynamics\nsimulation method, which is easy to implement and very efficient. We find that\nthe nucleation rates are predominately determined by the number of bonds per\nsphere in the system, rather than the precise details of the chain topology,\nchain length, and polymer composition. O ur results thus show that the crystal\nnucleation rate of bead chains can be enhanced by adding monomers to the\nsystem. In addition, we find that the resulting crystal n uclei contain\nsignificantly more face-centered-cubic than hexagonal-close-packed ordered\nparticles. More surprisingly, the resulting crystal nuclei possess a range of\ncrystal morphologies including structures with a five-fold symmetry.",
        "positive": "Scale dependence of mechanics and dynamics of active gels with\n  increasing motor concentration: The cytoskeleton protein actin assembles into large bundles when supporting\nstresses in the cell, but grows into a fine branched network to induce cell\nmotion. Such self-organization processes are studied in artificial networks of\ncytoskeleton proteins with thick actin bundles and large motor protein\naggregates to enable optical observation. The effect of motor aggregate size on\nthe cytoskeleton mechanical properties is studied here in networks comprised of\nmuch smaller motor assemblies. Large motor protein clusters are known to\nincrease the stiffness of actin based networks by introducing tension and\nadditional cross-linking cites. We find that these effects are universal to\nactin gels regardless of actin bundle thickness and motor aggregate size and\nare relevant, therefore, to a wide range of cytoskeleton based cellular\nprocesses. In contrast, motor induced active fluctuations depend significantly\non motor assembly size, featuring unique non-Gaussian statistics at high\nconcentrations of small assemblies."
    },
    {
        "anchor": "Pore-Scale Flow Characterization of Polymer Solutions in Microfluidic\n  Porous Media: Polymer solutions are frequently used in enhanced oil recovery and\ngroundwater remediation to improve the recovery of trapped non-aqueous fluids.\nHowever, applications are limited by an incomplete understanding of the flow in\nporous media. The tortuous pore structure imposes both shear and extension,\nwhich elongates polymers; moreover, the flow is often at large Weissenberg\nnumbers Wi at which polymer elasticity in turn strongly alters the flow. This\ndynamic elongation can even produce flow instabilities with strong spatial and\ntemporal fluctuations despite the low Reynolds number Re. Unfortunately,\nmacroscopic approaches are limited in their ability to characterize the\npore-scale flow. Thus, understanding how polymer conformations, flow dynamics,\nand pore geometry together determine these non-trivial flow patterns and impact\nmacroscopic transport remains an outstanding challenge. Here, we describe how\nmicrofluidic tools can shed light on the physics underlying the flow of polymer\nsolutions in porous media at high Wi and low Re. Specifically, microfluidic\nstudies elucidate how steady and unsteady flow behavior depends on pore\ngeometry and solution properties, and how polymer-induced effects impact\nnon-aqueous fluid recovery. This work provides new insights for polymer\ndynamics, non-Newtonian fluid mechanics, and applications such as enhanced oil\nrecovery and groundwater remediation.",
        "positive": "Topological aspect of disclinations in two-dimensional melting: By using topological current theory, we study the inner topological structure\nof disclinations during the melting of two-dimensional systems. From\ntwo-dimensional elasticity theory, it is found topological currents for\ntopological defects in homogeneous equation. The evolution of disclinations is\nstudied, and the branch conditions for generating, annihilating, crossing,\nsplitting, and merging of disclinations are given."
    },
    {
        "anchor": "Horizons and free path distributions in quasiperiodic Lorentz gases: We study the structure of quasiperiodic Lorentz gases, i.e., particles\nbouncing elastically off fixed obstacles arranged in quasiperiodic lattices. By\nemploying a construction to embed such structures into a higher dimensional\nperiodic hyperlattice, we give a simple and efficient algorithm for numerical\nsimulation of the dynamics of these systems. This same construction shows that\nquasiperiodic Lorentz gases generically exhibit a regime with infinite horizon,\nthat is, empty channels through which the particles move without colliding,\nwhen the obstacles are small enough; in this case, the distribution of free\npaths is asymptotically a power law with exponent -3, as expected from\ninfinite-horizon periodic Lorentz gases. For the critical radius at which these\nchannels disappear, however, a new regime with locally-finite horizon arises,\nwhere this distribution has an unexpected exponent of -5, previously observed\nonly in a Lorentz gas formed by superposing three incommensurable periodic\nlattices in the Boltzmann-Grad limit where the radius of the obstacles tends to\nzero.",
        "positive": "AC-field-induced Polarization for Uncharged Colloids in Salt Solution: A\n  Dissipative Particle Dynamics Simulation: We study the response of a spherical colloid under alternating electric\nfields (AC-fields) by mesoscopic simulation method, accounting in full for\nhydrodynamic and electrostatic interactions. We focus on a special case of\nuncharged colloids. The main polarization mechanism is the\n\"volume-polarization\", where ionic currents are deflected by the core of the\nuncharged colloid. Specifically, we compute the polarizability of a single\ncolloid and systematically investigate the effect of AC field frequency and\nsalt concentration. The simulation results are compared with predictions from\nclassical Maxwell-Wagner theory and electrokinetic theory."
    },
    {
        "anchor": "Sedimentation and polar order of active bottom-heavy particles: Self-propelled particles in an external gravitational field have been shown\nto display both an increased sedimentation length and polar order even without\nparticle interactions. Here, we investigate self-propelled particles which\nadditionally are bottom-heavy, that is they feel a torque aligning them to swim\nagainst the gravitational field. For bottom-heavy particles the gravitational\nfield has the two opposite effects of i) sedimentation and ii) upward alignment\nof the particles' swimming direction. We perform a multipole expansion of the\none-particle distribution with respect to orientation and derive expressions\nfor sedimentation length and mean particle orientation which we check against\nBrownian Dynamics simulations. For large strength of gravity or small particle\nspeeds and aligning torque, we observe sedimentation with increased\nsedimentation length compared with passive colloids but also active colloids\nwithout bottom-heaviness. Increasing, for example, swimming speed the\nsedimentation profile is inverted and the particles swim towards the top wall\nof the enclosing box. We find maximal orientational order at intermediate\nswimming speeds for both cases of particles with bottom-heaviness and those\nwithout. Ordering unsurprisingly is increased for the bottom-heavy particles,\nbut this difference disappears at higher levels of activity and for very high\nactivities ordering goes to zero in both cases.",
        "positive": "Hydrodynamic theory for nematic shells: the interplay among curvature,\n  flow and alignment: We derive the hydrodynamic equations for nematic liquid crystals lying on\ncurved substrates. We invoke the Lagrange-Rayleigh variational principle to\nadapt the Ericksen-Leslie theory to two-dimensional nematics in which a\ndegenerate anchoring of the molecules on the substrate is enforced. The only\nconstitutive assumptions in this scheme concern the free-energy density, given\nby the two-dimensional Frank potential, and the density of dissipation which is\nrequired to satisfy appropriate invariance requirements. The resulting\nequations of motion couple the velocity field, the director alignment and the\ncurvature of the shell. To illustrate our findings, we consider the effect of a\nsimple shear flow on the alignment of a nematic lying on a cylindrical shell."
    },
    {
        "anchor": "Importance of non-affine viscoelastic response in disordered fibre\n  networks: Disordered fibre networks are ubiquitous in nature and have a wide range of\nindustrial applications as novel biomaterials. Predicting their viscoelastic\nresponse is straightforward for affine deformations that are uniform over all\nlength scales, but when affinity fails, as has been observed experimentally,\nmodelling becomes challenging. Here we introduce a numerical methodology to\npredict the steady-state viscoelastic spectra and degree of affinity for\ndisordered fibre networks driven at arbitrary frequencies. Applying this method\nto a peptide gel model reveals a monotonic increase of the shear modulus as the\nsoft, non-affine normal modes are successively suppressed as the driving\nfrequency increases. In addition to being dominated by fibril bending, these\nlow frequency network modes are also shown to be delocalised. The presented\nmethodology provides insights into the importance of non-affinity in the\nviscoelastic response of peptide gels, and is easily extendible to all types of\nfibre networks.",
        "positive": "Minimal quantum viscosity from fundamental physical constants: Viscosity of fluids is strongly system-dependent, varies across many orders\nof magnitude and depends on molecular interactions and structure in a complex\nway not amenable to first-principles theories. Despite the variations and\ntheoretical difficulties, we find a new quantity setting the minimal kinematic\nviscosity of fluids: $\\nu_m=\\frac{1}{4\\pi}\\frac{\\hbar}{\\sqrt{m_em}}$, where\n$m_e$ and $m$ are electron and molecule masses. We subsequently introduce a new\nproperty, the \"elementary\" viscosity $\\iota$ with the lower bound set by\nfundamental physical constants and notably involving the proton-to-electron\nmass ratio:\n$\\iota_m=\\frac{\\hbar}{4\\pi}\\left({\\frac{m_p}{m_e}}\\right)^{\\frac{1}{2}}$, where\n$m_p$ is the proton mass. We discuss the connection of our result to the bound\nfound by Kovtun, Son and Starinets in strongly-interacting field theories."
    },
    {
        "anchor": "Simulating Colloid Hydrodynamics with Lattice Boltzmann: We present a progress report on our work on lattice Boltzmann methods for\ncolloidal suspensions. We focus on the treatment of colloidal particles in\nbinary solvents and on the inclusion of thermal noise. For a benchmark problem\nof colloids sedimenting and becoming trapped by capillary forces at a\nhorizontal interface between two fluids, we discuss the criteria for parameter\nselection, and address the inevitable compromise between computational\nresources and simulation accuracy.",
        "positive": "Charge Distribution on Annealed Polyelectrolytes: We investigate the equilibrium charge distribution along a single annealed\npolyelectrolyte chain under different conditions. The coupling between the\nconformation of the chain and the local charge distribution is described for\nvarious solvent qualities and salt concentration. In salt free solution, we\nfind a slight charge depletion in the central part of the chain: the charges\naccumulate at the ends. The effect is less important if salt is added to the\nsolution since the charge inhomogeneity is localized close to the chain ends\nover a distance of order of the Debye length. In the case of poor solvent\nconditions we find a different charging of beads and strings in the framework\nof the necklace model. This inhomogeneity leads to a charge instability and a\nfirst order transition between spherical globules and elongated chains."
    },
    {
        "anchor": "X-ray tomography of a crumpled plastoelastic thin sheet: A three-dimensional X-ray tomography is performed to investigate the internal\nstructure and its evolution of a crumpled aluminum foil. The upper and lower\nbounds of the internal geometric fractal dimension are determined, which\nincrease with the compression. Contrary to the simulation results, we find that\nthe mass distribution changes from being inhomogeneous to uniform. Corroborated\nwith the evidence from previous experiments, these findings support the\nphysical picture that the elastic property precedes the plastic one at\ndominating the deformation and mechanical response for all crumpled structures.\nWe show that the interior of a crumpled ball at the plastic regime can be\nmapped to the compact packing of a granular system.",
        "positive": "Kinetics of spontaneous filament nucleation via oligomers: insights from\n  theory and simulation: Nucleation processes are at the heart of a large number of phenomena, from\ncloud formation to protein crystallization. A recently emerging area where\nnucleation is highly relevant is the initiation of filamentous protein\nself-assembly, a process that has broad implications from medicine to\nnanotechnology. As such, spontaneous nucleation of protein fibrils has received\nmuch attention in recent years with many theoretical and experimental studies\nfocussing on the underlying physical principles. In this paper we make a step\nforward in this direction and explore the early time behaviour of filamentous\nprotein growth in the context of nucleation theory. We first provide an\noverview of the thermodynamics and kinetics of spontaneous nucleation of\nprotein filaments in the presence of one relevant degree of freedom, namely the\ncluster size. In this case, we review how key kinetic observables, such as the\nreaction order of spontaneous nucleation, are directly related to the physical\nsize of the critical nucleus. We then focus on the increasingly prominent case\nof filament nucleation that includes a conformational conversion of the\nnucleating building-block as an additional slow step in the nucleation process.\nUsing computer simulations, we study the concentration dependence of the\nnucleation rate. We find that, under these circumstances, the reaction order of\nspontaneous nucleation with respect to the free monomer does no longer relate\nto the overall physical size of the nucleating aggregate but rather to the\nportion of the aggregate that actively participates in the conformational\nconversion. Our results thus provide a novel interpretation of the common\nkinetic descriptors of protein filament formation, including the reaction order\nof the nucleation step or the scaling exponent of lag times, and put into\nperspective current theoretical descriptions of protein aggregation."
    },
    {
        "anchor": "Coexistence of hexatic and isotropic phases in two-dimensional Yukawa\n  systems: We have performed Brownian dynamics simulations on melting of two-dimensional\ncolloidal crystal in which particles interact with Yukawa potential. The pair\ncorrelation function and bond-orientational correlation function was calculated\nin the Yukawa system. An algebraic decay of the bond orientational correlation\nfunction was observed. By ruling out the coexistence region, only a unstable\nhexatic phase was found in the Yukawa systems. But our work shows that the\nmelting of the Yukawa systems is a two-stage melting not consist with the KTHNY\ntheory and the isotropic liquid and the hexatic phase coexistence region was\nfound. Also we have studied point defects in two-dimensional Yukawa systems.",
        "positive": "Cell spheroid viscoelasticity is deformation-dependent: Tissue surface tension influences cell sorting and tissue fusion. Earlier\nmechanical studies suggest that multicellular spheroids actively reinforce\ntheir surface tension with applied force. Here we study this open question\nthrough high-throughput microfluidic micropipette aspiration measurements on\ncell spheroids to identify the role of force duration and cell contractility.\nWe find that larger spheroid deformations lead to faster cellular retraction\nonce the pressure is released, regardless of the applied force and cellular\ncontractility. These new insights demonstrate that spheroid viscoelasticity is\ndeformation-dependent and challenge whether surface tension truly reinforces."
    },
    {
        "anchor": "Universal Jamming Phase Diagram in the Hard-Sphere Limit: We present a new formulation of the jamming phase diagram for a class of\nglass-forming fluids consisting of spheres interacting via finite-ranged\nrepulsions at temperature $T$, packing fraction $\\phi$ or pressure $p$, and\napplied shear stress $\\Sigma$. We argue that the natural choice of axes for the\nphase diagram are the dimensionless quantities $T/p\\sigma^3$,\n$p\\sigma^3/\\epsilon$, and $\\Sigma/p$, where $T$ is the temperature, $p$ is the\npressure, $\\Sigma$ is the stress, $\\sigma$ is the sphere diameter, $\\epsilon$\nis the interaction energy scale, and $m$ is the sphere mass. We demonstrate\nthat the phase diagram is universal at low $p\\sigma^3/\\epsilon$; at low\npressure, observables such as the relaxation time are insensitive to details of\nthe interaction potential and collapse onto the values for hard spheres,\nprovided the observables are non-dimensionalized by the pressure. We determine\nthe shape of the jamming surface in the jamming phase diagram, organize\nprevious results in relation to the jamming phase diagram, and discuss the\nsignificance of various limits.",
        "positive": "Reshaping elastic nanotubes via self-assembly of surface-adhesive\n  nanoparticles: Elastic sheets with macroscopic dimensions are easy to deform by bending and\nstretching. Yet shaping nanometric sheets by mechanical manipulation is hard.\nHere we show that nanoparticle self-assembly could be used to this end. We\ndemonstrate by Monte Carlo simulation that spherical nanoparticles adhering to\nthe outer surface of an elastic nanotube can self-assemble into linear\nstructures as a result of curvature-mediated interactions. We find that\nnanoparticles arrange into rings or helices on stretchable nanotubes, and as\naxial strings on nanotubes with high rigidity to stretching. These\nself-assembled structures are inextricably linked to a variety of deformed\nnanotube profiles, which can be controlled by tuning the concentration of\nnanoparticles, the nanoparticle-nanotube diameter ratio and the elastic\nproperties of the nanotube. Our results open the possibility of designing\nnanoparticle-laden tubular nanostructures with tailored shapes, for potential\napplications in materials science and nanomedicine."
    },
    {
        "anchor": "Lipid exchange promotes fusion of model protocells: Vesicle fusion is an important process underlying cell division, transport,\nand membrane trafficking. In phospholipid systems, a range of fusogens\nincluding divalent cations and depletants have been shown to induce adhesion,\nhemifusion, and then full content fusion between vesicles. This works shows\nthat these fusogens do not perform the same function for fatty acid vesicles,\nwhich are used as model protocells (primitive cells). Even when fatty acid\nvesicles appear adhered or hemifused to each other, the intervening barriers\nbetween vesicles do not rupture. This difference is likely because fatty acids\nhave a single aliphatic tail, and are more dynamic than their phospholipid\ncounterparts. To address this, we postulate that fusion could instead occur\nunder conditions, such as lipid exchange, that disrupt lipid packing. Using\nboth experiments and molecular dynamics simulations, we verify that fusion in\nfatty acid systems can indeed be induced by lipid exchange. These results begin\nto probe how membrane biophysics could constrain the evolutionary dynamics of\nprotocells.",
        "positive": "Characterizing Granular Networks Using Topological Metrics: We carry out a direct comparison of experimental and numerical realizations\nof the exact same granular system as it undergoes shear jamming. We adjust the\nnumerical methods used to optimally represent the experimental settings and\noutcomes up to microscopic contact force dynamics. Measures presented here\nrange form microscopic, through mesoscopic to system-wide characteristics of\nthe system. Topological properties of the mesoscopic force networks provide a\nkey link between micro and macro scales. We report two main findings: the\nnumber of particles in the packing that have at least two contacts is a good\npredictor for the mechanical state of the system, regardless of strain history\nand packing density. All measures explored in both experiments and numerics,\nincluding stress tensor derived measures and contact numbers depend in a\nuniversal manner on the fraction of non-rattler particles, $f_{NR}$. The force\nnetwork topology also tends to show this universality, yet the shape of the\nmaster curve depends much more on the details of the numerical simulations. In\nparticular we show that adding force noise to the numerical data set can\nsignificantly alter the topological features in the data. We conclude that both\n$f_{NR}$ and topological metrics are useful measures to consider when\nquantifying the state of a granular system."
    },
    {
        "anchor": "Local pressure for confined systems: We derive a general closed expression for the local pressure exerted onto the\ncorrugated walls of a channel confining a fluid medium. When the fluid medium\nis at equilibrium the local pressure is a functional of the shape of the walls.\nIt is shown that, due to the intrinsic non-local character of the interactions\namong the particles forming the fluid, the applicability of approximate schemes\nsuch as the concept of a surface of tension or morphometric thermodynamics is\nlimited to wall curvatures small compared to the range of particle-particle\ninteractions.",
        "positive": "Unjamming a granular hopper by vibration: We present an experimental study of the outflow of a hopper continuously\nvibrated by a piezoelectric device. Outpouring of grains can be achieved for\napertures much below the usual jamming limit observed for non vibrated hoppers.\nGranular flow persists down to the physical limit of one grain diameter, a\nlimit reached for a finite vibration amplitude. For the smaller orifices, we\nobserve an intermittent regime characterized by alternated periods of flow and\nblockage. Vibrations do not significantly modify the flow rates both in the\ncontinuous and the intermittent regime. The analysis of the statistical\nfeatures of the flowing regime shows that the flow time significantly increases\nwith the vibration amplitude. However, at low vibration amplitude and small\norifice sizes, the jamming time distribution displays an anomalous statistics."
    },
    {
        "anchor": "No free lunch for effective potentials: general comment for Faraday\n  FD144: I briefly review the problem of representability -- a single coarse-grained\neffective pair potential cannot simultaneously represent all the properties of\nan underlying more complex system -- as well as a few other subtleties that can\narise in interpreting coarse-grained potentials.",
        "positive": "Unjamming in models with analytic pairwise potentials: The canonical models for studying the unjamming scenario in systems of soft\nrepulsive particles assume pairwise potentials with a sharp cut-off in the\ninteraction range. The sharp cut-off renders the potential non-analytic, but\nmakes it possible to describe many properties of the solid in terms of the\ncoordination number $z$, which has an unambiguous definition in these cases.\nPairwise potentials without a sharp cut-off in the interaction range have not\nbeen considered in this context, but are of interest for understanding the\nrelevance of the unjamming phenomenology to systems in which such a cut-off\ncannot be assumed. In this work we explore two systems with such interactions:\nan inverse power law and an exponentially decaying pairwise potential, with the\ncontrol parameters being the exponent (of the inverse power-law) for the former\nand the number density for the latter. Both systems are shown to exhibit the\ncharacteristic features of the unjamming transition, among which are the\nvanishing of the shear to bulk modulus ratio and the emergence of an excess of\nlow-frequency vibrational modes. We establish a relation between the\nhydrostatic pressure to bulk modulus ratio and the distance to unjamming in\neach of our model systems. This allows us to predict the dependence of other\nkey observables on the distance to unjamming. Our results provide the means for\na quantitative estimation of the proximity of generic glass forming models to\nthe unjamming transition in the absence of a clear-cut definition of the\ncoordination number, and highlight the general irrelevance of nonaffine\ncontributions to the bulk modulus."
    },
    {
        "anchor": "Fluctuations, Jamming, and Yielding for a Driven Probe Particle in\n  Disordered Disk Assemblies: Using numerical simulations we examine the velocity fluctuations of a probe\nparticle driven with constant force through a two-dimensional disordered\nassembly of disks which has a well-defined jamming point J at a density of\n\\phi_J=0.843. As \\phi increases toward \\phi_J, the average velocity of the\nprobe particle decreases and the velocity fluctuations show an increasingly\nintermittent or avalanchelike behavior. When the system is within a few percent\nof the jamming density, the velocity distributions are exponential, while when\nthe system is less than a percent away from jamming, the velocity distributions\nhave a non-exponential or power law character. The velocity power spectra\nexhibit a crossover from a Lorentzian form to a 1/f shape near jamming. We\nextract a correlation exponent \\nu which is in good agreement with recent shear\nsimulations. For \\phi > \\phi_J, there is a critical threshold force F_c that\nmust be applied for the probe particle to move through the sample which\nincreases with increasing \\phi. The onset of the probe motion above \\phi_J\noccurs via a local yielding of the particles around the probe particle which we\nterm a local shear banding effect.",
        "positive": "Wetting regimes and interactions of parallel plane surfaces in a polar\n  liquid: We apply a phenomenological theory of polar liquids to calculate the\ninteraction energy between two plane surfaces at nm-distances. We show that\ndepending on the properties of the surface-liquid interfaces, the interacting\nsurfaces induce polarization of the liquid in different ways. We find, in full\nagreement with available experiments, that if the interfaces are mostly\nhydrophobic, then the interaction is attractive and relatively long-ranged\n(interaction decay length \\lambda\\sim1.2\\, nm). The water molecules are net\npolarized parallel to the surfaces in this case. If the surfaces are mostly\nhydrophilic, then the molecules are polarized against the surfaces, and the\ninteraction becomes repulsive, but at a short-range (\\lambda\\sim0.2\\, nm).\nFinally, we predict there exists an intermediate regime, where the surfaces\nfail to order the water molecules, the interaction becomes much weaker,\nattractive and, at relatively small distances, decays with the inverse square\nof the distance between the surfaces."
    },
    {
        "anchor": "Dynamic effective mass of granular media and the attenuation of\n  structure-borne sound: We report an experimental and theoretical investigation of the\nfrequency-dependent effective mass, $\\tilde{M}(\\omega)$, of loose granular\nparticles which occupy a rigid cavity to a given filling fraction, the\nremaining volume being air of differing humidities. This allow us to study the\nmechanisms of elastic response and attenuation of acoustic modes in granular\nmedia. We demonstrate that this is a sensitive and direct way to measure those\nproperties of the granular medium that are the cause of the changes in acoustic\nproperties of structures containing grain-filled cavities. Specifically, we\napply this understanding to the case of the flexural resonances of a\nrectangular bar with a grain-filled cavity within it. The dominant features of\n$\\tilde{M}(\\omega)$ are a sharp resonance and a broad background, which we\nanalyze within the context of simple models. We find that: a) These systems may\nbe understood in terms of a height-dependent and diameter-dependent effective\nsound speed ($\\sim 100-300$ m/s) and an effective viscosity ($\\sim 5\\times\n10^4$ Poise). b) There is a dynamic Janssen effect in the sense that, at any\nfrequency, and depending on the method of sample preparation, approximately\none-half of the effective mass is borne by the side walls of the cavity and\none-half by the bottom. c) By performing experiments under varying humidity\nconditions we conclude that, on a fundamental level, damping of acoustic modes\nis dominated by adsorbed films of water at grain-grain contacts in our\nexperiments, not by global viscous dampening. d) There is a monotonically\nincreasing effect of humidity on the dampening of the fundamental resonance\nwithin the granular medium which translates to a non-monotonic, but\npredictable, variation of dampening within the grain-loaded bar.",
        "positive": "Optical penetration depth and periodic motion of a photomechanical strip: Liquid crystal elastomers (LCEs) containing light-sensitive molecules exhibit\nlarge reversible deformation when subjected to illumination. Here, we\ninvestigate the role of optical penetration depth on this photomechanical\nresponse. We present a model of the photomechanical behavior of photoactive LCE\nstrips under illumination that goes beyond the common assumption of shallow\npenetration. This model reveals how the optical penetration depth and the\nconsequent photomechanically induced deformation can depend on the\nconcentration of photoactive molecules, their absorption cross-sections, and\nthe intensity of illumination. Through a series of examples, we show that the\npenetration depth can quantitatively and qualitatively affect the\nphotomechanical response of a strip. Shallow illumination leads to monotone\ncurvature change while deep penetration can lead to non-monotone response with\nillumination duration. Further, the flapping behavior (a cyclic wave-like\nmotion) of doubly clamped and buckled strips that has been proposed for\nlocomotion can reverse direction with sufficiently large penetration depth.\nThis opens the possibility of creating wireless light-driven photomechanical\nactuators and swimmers whose direction of motion can be controlled by light\nintensity and frequency."
    },
    {
        "anchor": "EXCOGITO, an extensible coarse-graining toolbox for the investigation of\n  biomolecules by means of low-resolution representation: Bottom-up coarse-grained (CG) models proved to be essential to complement and\nsometimes even replace all-atom representations of soft matter systems and\nbiological macromolecules. The development of low-resolution models takes the\nmoves from the reduction of the degrees of freedom employed, that is, the\ndefinition of a mapping between a system's high-resolution description and its\nsimplified counterpart. Even in absence of an explicit parametrisation and\nsimulation of a CG model, the observation of the atomistic system in simpler\nterms can be informative: this idea is leveraged by the mapping entropy, a\nmeasure of the information loss inherent to the process of coarsening. Mapping\nentropy lies at the heart of the extensible coarse-graining toolbox, or\nEXCOGITO, developed to perform a number of operations and analyses on molecular\nsystems pivoting around the properties of mappings. EXCOGITO can process an\nall-atom trajectory to compute the mapping entropy, identify the mapping that\nminimizes it, and establish quantitative relations between a low-resolution\nrepresentation and geometrical, structural, and energetic features of the\nsystem. Here, the software, which is available free of charge under an open\nsource licence, is presented and showcased to introduce potential users to its\ncapabilities and usage.",
        "positive": "Structural behavior and dynamics of an anomalous fluid between\n  solvophilic and solvophobic walls: templating, molding and superdiffusion: Confinement can modify the dynamics, the thermodynamics and the structural\nproperties of liquid water, the prototypical anomalous liquid. By considering a\ngeneral anomalous liquid, suitable for globular proteins, colloids or liquid\nmetals, we study by molecular dynamics simulations the effect of a solvophilic\nstructured and a solvophobic unstructured wall on the phases, the crystal\nnucleation and the dynamics of the fluid. We find that at low temperatures the\nlarge density of the solvophilic wall induces a high-density, high-energy\nstructure in the first layer (\"tempting\" effect). In turn, the first layer\ninduces a \"molding\" effect on the second layer determining a structure with\nreduced energy and density, closer to the average density of the system. This\nlow-density, low-energy structure propagates further through the layers by\ntemplating effect and can involve all the existing layers at the lowest\ntemperatures investigated. Therefore, although the high-density, high-energy\nstructure does not self-reproduce further than the first layer, the structured\nwall can have a long-range effect thanks to a sequence of templating, molding\nand templating effects through the layers. We find dynamical slowing down of\nthe solvent near the solvophilic wall but with largely heterogeneous dynamics\nnear the wall due to superdiffusive liquid veins within a frozen matrix of\nsolvent. Hence, the partial freezing of the first hydration layer does not\ncorrespond necessarily to an effective reduction of the channel section in\nterms of transport properties."
    },
    {
        "anchor": "Valorization of byproducts of hemp multipurpose crops: short non-aligned\n  bast fibers as a source of nanocellulose: Nanocellulose was extracted from short bast fibers, from hemp (Cannabis\nSativa L.) plants harvested at seed maturity, non-retted, mechanically\ndecorticated in a defibering apparatus giving non-aligned fibers. A chemical\npretreatment with NaOH and HCl allowed the removal of most of the\nnon-cellulosic components of the fibers. No bleaching was performed. The\nchemically pretreated fibers were then refined in a beater and treated with a\ncellulase enzyme, before the mechanical defibrillation in an ultrafine friction\ngrinder. The fibers were characterized by microscopy, infrared spectroscopy,\nthermogravimetric analysis, and X-ray diffraction after each step of the\nprocess, to understand the evolution of their morphology and composition. The\nobtained nanocellulose suspension was composed of rod-like fibrils with widths\nof 5-12 nm, stacks of nanofibrils with widths of 20-200 nm, and some larger\nfibers. The crystallinity index was found to increase from 74% for the raw\nfibers to 80% for the nanocellulose. The nanocellulose retained a yellowish\ncolor indicating the presence of some residual lignin. Properties of nanopaper\nprepared with the hemp nanocellulose were similar to those of nanopapers\nprepared with wood pulp derived rod-like nanofibrils.",
        "positive": "Mechanisms of Diffusional Nucleation of Nanocrystals and Their\n  Self-Assembly into Uniform Colloids: We survey our research on modeling the mechanisms of control of uniformity in\ngrowth of nanosize and colloid particles. The former are produced as\nnanocrystals, by burst-nucleation from solution. The latter, colloid-size\nparticles, are formed by self-assembly (aggregation) of the nanocrystals. In\nthe colloid particle synthesis, the two dynamical processes are coupled, and\nboth are governed by diffusional transport of the respective building blocks\n(monomers). The interrelation of the two processes allows for synthesis of\nnarrow size distribution colloid dispersions which are of importance in many\napplications.\n  We first review a mathematical model of diffusive cluster growth by capture\nof monomer \"singlets.\" Burst nucleation of nanoparticles in solution is then\nanalyzed. Finally, we couple it to the secondary process of aggregation of\nnanoparticles to form colloids, and we discuss various aspects of the modeling\nof particle size distribution, as well as other features of the processes\nconsidered."
    },
    {
        "anchor": "Surface pressure and shear stress field within a frictional contact on\n  rubber: This paper addresses the issue of the determination of the frictional stress\ndistribution from the inversion of the measured surface displacement field for\nsliding interfaces between a glass lens and a rubber (poly(dimethylsiloxane))\nsubstrate. Experimental results show that high lateral strains are achieved at\nthe periphery of the sliding contacts. As a consequence, an accurate inversion\nof the displacement field requires that finite strains and non linear response\nof the rubber substrate are taken into account. For that purpose, a Finite\nElement (FE) inversion procedure is implemented where the measured displacement\nfield is applied as a boundary condition at the upper surface of a meshed body\nrepresenting the rubber substrate. Normal pressure is also determined by the\nsame way, if non-diverging values are assumed at the contact edge. This\nprocedure is applied to linearly sliding contacts as well as on twisting\ncontacts.",
        "positive": "Fluid-fluid demixing and density anomaly in a ternary mixture of hard\n  spheres: We report the grand-canonical solution of a ternary mixture of discrete hard\nspheres defined on a Husimi lattice built with cubes, which provides a\nmean-field approximation for this system on the cubic lattice. The mixture is\ncomposed by point-like particles (0NN) and particles which exclude up to their\nfirst (1NN) and second neighbors (2NN), with activities $z_0$, $z_1$ and $z_2$,\nrespectively. Our solution reveals a very rich thermodynamic behavior, with two\nsolid phases associated with the ordering of 1NN ($S1$) or 2NN particles\n($S2$), and two fluid phases, being one regular ($RF$) and the other\ncharacterized by a dominance of 0NN particles ($F0$ phase). However, in most\npart of the phase diagram these fluid ($F$) phases are indistinguishable.\nDiscontinuous transitions are observed between all the four phases, yielding\nseveral coexistence surfaces in the system, among which a fluid-fluid and a\nsolid-solid demixing surface. The former one is limited by a line of critical\npoints and a line of triple points (where the phases $RF$-$F0$-$S2$ coexist),\nboth meeting at a special point, after which the fluid-fluid coexistence\nbecomes metastable. Another line of triple points is found, connecting the\n$F$-$S1$, $F$-$S2$ and $S1$-$S2$ coexistence surfaces. A critical $F$-$S1$\nsurface is also observed meeting the $F$-$S1$ coexistence one at a line of\ntricritical points. Furthermore, a thermodynamic anomaly characterized by\nminima in isobaric curves of the total density of particles is found, yielding\nthree surfaces of minimal density in the activity space, depending on which\nactivity is kept fixed during its calculation."
    },
    {
        "anchor": "Statistical Properties of Interacting Bose Gases in Quasi-2D Harmonic\n  Traps: The analytical probability distribution of the quasi-2D (and purely 2D) ideal\nand interacting Bose gas are investigated by using a canonical ensemble\napproach. Using the analytical probability distribution of the condensate, the\nstatistical properties such as the mean occupation number and particle number\nfluctuations of the condensate are calculated. Researches show that there is a\ncontinuous crossover of the statistical properties from a quasi-2D to a purely\n2D ideal or interacting gases. Different from the case of a 3D Bose gas, the\ninteraction between atoms changes in a deep way the nature of the particle\nnumber fluctuations.",
        "positive": "Epithelial Tissue Growth Dynamics: Universal or Not?: Universality of interfacial roughness in growing epithelial tissue has\nremained a controversial issue. Kardar-Parisi-Zhang (KPZ) and Molecular Beam\nEpitaxy (MBE) universality classes have been reported among other behaviors\nincluding total lack of universality. Here, we utilize a kinetic division model\nfor deformable cells to investigate cell-colony scaling. With seemingly minor\nmodel changes, it can reproduce both KPZ- and MBE-like scaling in\nconfigurations that mimic the respective experiments. This result neutralizes\nthe apparent scaling controversy. It can be speculated that this diversity in\ngrowth behavior is beneficial for efficient evolution and versatile growth\ndynamics."
    },
    {
        "anchor": "Structure factor of polymers interacting via a short range repulsive\n  potential: application to hairy wormlike micelles: We use the Random Phase Approximation (RPA) to compute the structure factor,\nS(q), of a solution of chains interacting through a soft and short range\nrepulsive potential V. Above a threshold polymer concentration, whose magnitude\nis essentially controlled by the range of the potential, S(q) exhibits a peak\nwhose position depends on the concentration. We take advantage of the close\nanalogy between polymers and wormlike micelles and apply our model, using a\nGaussian function for V, to quantitatively analyze experimental small angle\nneutron scattering profiles of semi-dilute solutions of hairy wormlike\nmicelles. These samples, which consist in surfactant self-assembled flexible\ncylinders decorated by amphiphilic copolymer, provide indeed an appropriate\nexperimental model system to study the structure of sterically interacting\npolymer solutions.",
        "positive": "A microscopic picture of erosion and sedimentation processes in dense\n  granular flows: Gravity-driven flows of granular matter are involved in a wide variety of\nsituations, ranging from industrial processes to geophysical phenomena, such as\navalanches or landslides. These flows are characterized by the coexistence of\nsolid and fluid phases, whose stability is directly related to the erosion and\nsedimentation occurring at the solid-fluid interface. To describe these\nmechanisms, we build a microscopic model involving friction, geometry, and a\nnonlocal cooperativity emerging from the propagation of collisions. This new\npicture enables us to obtain a detailed description of the exchanges between\nthe fluid and solid phases. The model predicts a phase diagram including\nerosion, sedimentation, and stationary-flow regimes, in quantitative agreement\nwith experiments and discrete-element-method simulations."
    },
    {
        "anchor": "Thermodynamics of the incommensurate state in Rb_2WO_4: on the Lifshitz\n  point in A`A``BX_4 compounds: We consider the evolution of the phase transition from the parent hexagonal\nphase $P6_{3}/mmc$ to the orthorhombic phase $Pmcn$ that occurs in several\ncompounds of $A'A''BX_{4}$ family as a function of the hcp lattice parameter\n$c/a$. For compounds of $K_{2}SO_{4}$ type with $c/a$ larger than the threshold\nvalue 1.26 the direct first-order transition $Pmcn-P6_{3}/mmc$ is characterized\nby the large entropy jump $Rln2$. For compounds $Rb_{2}WO_{4}$, $K_{2}MoO_{4}$,\n$K_{2}WO_{4}$ with $c/a<1.26$ this transition occurs via an intermediate\nincommensurate $(Inc)$ phase. DSC measurements were performed in $Rb_{2}WO_{4}$\nto characterize the thermodynamics of the $Pmcn-Inc-P6_{3}/mmc$ transitions. It\nwas found that both transitions are again of the first order with entropy jumps\n$0.2Rln2 and $0.3Rln2$. Therefore, at $c/a ~ 1.26$ the $A'A''BX_{4}$ compounds\nreveal an unusual Lifshitz point where three first order transition lines meet.\nWe propose the coupling of crystal elasticity with $BX_{4}$ tetrahedra\norientation as a possible source of the transitions discontinuity.",
        "positive": "Theory of Gel Formation: Test of the Gel Theory by Ilavsky Experiments: The theory of gelation is tested by the recent experiments in poly(urethane)\nnetwork. The result supports strongly the physical soundness of the theory."
    },
    {
        "anchor": "Linking microscopic and macroscopic response in disordered solids: The modulus of a rigid network of harmonic springs depends on the sum of the\nenergies in each of the bonds due to the applied distortion: compression in the\ncase of the bulk modulus, $B$, or shear in the case of the shear modulus,\n$\\mathcal{G}$. The distortion need not be global and we introduce a local\nmodulus, $L_{i}$, associated with changing the equilibrium length of a single\nbond, $i$, in the network. We show that $L_{i}$ is useful for understanding\nmany aspects of the mechanical response of the entire system. For example, it\nallows an understanding, and efficient computation, of how each bond in a\nnetwork contributes to global properties such as $B$ and $\\mathcal{G}$ and\nsheds light on how a particular bond's contribution to one modulus is, or is\nnot, correlated with its contribution to another.",
        "positive": "Electrooptics of mm-scale polar domains in the ferroelectric splay\n  nematic phase: The recent discovery of the ferroelectric splay nematic phase has opened the\ndoor to experimental investigation of one of the most searched liquid crystal\nphases in decades, with high expectations for future applications. However, at\nthis moment, there are more questions than answers. In this work, we examine\nthe formation and structure of large polar nematic domains of the ferroelectric\nsplay nematic material RM734 in planar liquid crystals cells with different\naligning agents and specifications. We observe that confining surfaces have a\nstrong influence over the formation of different types of domains, resulting in\nvarious twisted structures of the nematic director. For those cells\npredominantly showing mm-scale domains, we investigate the optical and second\nharmonic generation switching behaviour under applications of electric fields\nwith a special focus on in-plane fields perpendicular to the confinement media\nrubbing direction. In order to characterize the underlying structure, the polar\noptical switching behaviour is reproduced using a simplified model together\nwith Berreman calculations."
    },
    {
        "anchor": "Relaxation dynamics, Softness and Fragility of Microgels with\n  Interpenetrated Polymer Networks: Microgels are elastic and deformable particles with a hybrid nature between\nthat of polymers and colloids and unconventional behaviours with respect to\nhard colloids. We investigated the dynamics of a soft microgel made of\ninterpenetrated polymer networks of PNIPAM and PAAc by means of coherent X-ray\nand light scattering techniques. By varying the particle softness through PAAc\ncontent we can tune at wish the fragility of IPN microgels. Interestingly we\nfind the occurrence of a dynamical crossover at a critical weight concentration\nwhich leads to an evolution of the structural relaxation time from a\nsuper-Arrhenius to a slower than Arrhenius behaviour, a minimum for the shape\nparameter of intensity autocorrelation function and the emerging of distinct\nanomalous mechanisms for particle motion. This complex phenomenology can be\ndescribed by a Fickian diffusion at very low concentrations, an effective non\nFickian anomalous diffusion at intermediate values and a ballistic motion well\ndescribed within the Mode Coupling Theory.",
        "positive": "Effects of inertia on conformation and dynamics of tangentially-driven\n  active filaments: Active filament-like systems propelling along their backbone exist across the\nscales ranging from motor-driven bio-filaments to worms and robotic chains. In\nmacroscopic active filaments such as chain of robots, in contrast to their\nmicroscopic counterparts, inertial effects on their motion cannot be ignored.\nNonetheless, consequences of interplay between inertia and flexibility on shape\nand dynamics of active filaments remain unexplored. Here, we examine inertial\neffects on flexible tangentially-driven active polymer model pertinent to above\nexamples and we determine the conditions under which inertia becomes important.\nPerforming Langevin dynamics simulations of active polymers with underdamped\nand overdamped dynamics for a wide range of contour lengths and activities, we\nuncover striking inertial effects on conformation and dynamics at high\nactivities. Inertial collisions increase the persistence length of active\npolymers and remarkably alter their scaling behavior. In stark contrast to\npassive polymers, inertia leaves its fingerprint at long times by an enhanced\ndiffusion of the center of mass. We rationalize inertia-induced enhanced\ndynamics by analytical calculations of center of mass velocity correlations,\napplicable to any active polymer model, which reveal significant contributions\nfrom active force fluctuations convoluted by inertial relaxation."
    },
    {
        "anchor": "AC electrolyte conductivity in the $\u03c9\u03c4<1$ regime: Details of the dynamic behaviour of different charged clusters in liquids are\ndiscussed. Their associated mass is considered which possesses a number of\ninteresting features in a normal viscous liquid.",
        "positive": "Morphomechanical model of the torsional c-looping in the embryonic heart: Before septation processes shape its four chambers, the embryonic heart is a\nstraight tube that spontaneously bends and twists breaking the left-right\nsymmetry. In particular, the heart tube is subjected to a cell remodelling\ninducing ventral bending and dextral torsion during the c-looping phase. In\nthis work we propose a morphomechanical model for the torsion of the heart\ntube, that behaves as a nonlinear elastic body. We hypothesize that this\nspontaneous looping can be modeled as a mechanical instability due to\naccumulation of residual stresses induced by the geometrical frustration of\ntissue remodelling, which mimics the cellular rearrangement within the heart\ntube. Thus, we perform a linear stability analysis of the resulting nonlinear\nelastic boundary value problem to determine the onset of c-looping as a\nfunction of the aspect ratios of the tube and of the internal remodelling rate.\nWe perform numerical simulations to study the fully nonlinear morphological\ntransition, showing that the soft tube develops a realistic self-contacting\nlooped shape in the physiological range of geometrical parameters."
    },
    {
        "anchor": "Charge affinity and solvent effects in numerical simulations of ionic\n  microgels: Ionic microgel particles are intriguing systems in which the properties of\nthermo-responsive polymeric colloids are enriched by the presence of charged\ngroups. In order to rationalize their properties and predict the behaviour of\nmicrogel suspensions, it is necessary to develop a coarse-graining strategy\nthat starts from the accurate modelling of single particles. Here, we provide a\nnumerical advancement of a recently-introduced model for charged co-polymerized\nmicrogels by improving the treatment of ionic groups in the polymer network. We\ninvestigate the thermoresponsive properties of the particles, in particular\ntheir swelling behaviour and structure, finding that, when charged groups are\nconsidered to be hydrophilic at all temperatures, highly charged microgels do\nnot achieve a fully collapsed state, in favorable comparison to experiments. In\naddition, we explicitly include the solvent in the description and put forward\na mapping between the solvophobic potential in the absence of the solvent and\nthe monomer-solvent interactions in its presence, which is found to work very\naccurately for any charge fraction of the microgel. Our work paves the way for\ncomparing single-particle properties and swelling behaviour of ionic microgels\nto experiments and to tackle the study of these charged soft particles at a\nliquid-liquid interface.",
        "positive": "Cholesteric Phase in Virus Suspensions: We report measurements of the cholesteric pitch and twist elastic constant\n$(K_{22})$ in monodisperse suspensions of the rod-like virus filamentous\nbacteriophage {\\it fd}. Measurements were taken for concentrations spanning the\nentire cholesteric region at several ionic strengths and temperatures. In the\nlimit of high ionic strength the cholesteric pitch $(P_0)$ scales with\nconcentration (c) as $P_0 \\propto c^{-1.66}$. As the ionic strength decreases\nthe scaling exponent systematically changes to lower values."
    },
    {
        "anchor": "Diffusion and Velocity Auto-Correlation in Shearing Granular Media: We perform numerical simulations to examine particle diffusion at steady\nshear in a model granular material in two dimensions at the jamming density and\nzero temperature. We confirm findings by others that the diffusion constant\ndepends on shear rate as $D\\sim\\dot\\gamma^{q_D}$ with $q_D<1$, and set out to\ndetermine a relation between $q_D$ and other exponents that characterize the\njamming transition. We then examine the the velocity auto-correlation function,\nnote that it is governed by two processes with different time scales, and\nidentify a new fundamental exponent, $\\lambda$, that characterizes an algebraic\ndecay of correlations with time.",
        "positive": "The contact dynamics method for granular media: In this paper we review the simulation method of the non-smooth contact\ndynamics. This technique was designed to solve the unilateral and frictional\ncontact problem for a large number of rigid bodies and has proved to be\nespecially valuable in research of dense granular materials during the last\ndecade. We present here the basic principles compared to other methods and the\ndetailed description of a 3D algorithm. We point out an artifact manifesting\nitself in spurious sound waves and discuss the applicability of the method."
    },
    {
        "anchor": "Granular Impact Model as an Energy-Depth Relation: Velocity-squared drag forces are common in describing an object moving\nthrough a granular material. The resulting force law is a nonlinear\ndifferential equation, and closed-form solutions of the dynamics are typically\nobtained by making simplifying assumptions. Here, we consider a generalized\nversion of such a force law which has been used in many studies of granular\nimpact. We show that recasting the force law into an equation for the kinetic\nenergy versus depth, K(z), yields a linear differential equation, and thus\ngeneral closed-form solutions for the velocity versus depth. This approach also\nhas several advantages in fitting such models to experimental data, which we\ndemonstrate by applying it to data from 2D impact experiments. We also present\nnew experimental results for this model, including shape and depth dependence\nof the velocity-squared drag force.",
        "positive": "Weak chaos and fractional dynamics in an optically driven colloidal ring: Three colloidal spheres driven around a ring-like optical trap known as an\noptical vortex have been predicted to undergo periodic collective motion due to\ntheir hydrodynamic coupling. In fact, the quenched disorder in the\noptically-implemented potential energy landscape drives a transition to\ninstability evolving into microscopic weak chaos with fractional dynamics. As a\nresult, the relation between the space-time selfsimilarity of the system's\ncollective transport properties and its microscopic weak chaos dynamics is\nrevealed."
    },
    {
        "anchor": "Estimating Entropy of Liquids from Atom-Atom Radial Distribution\n  Functions: Silica, Beryllium Fluoride and Water: Molecular dynamics simulations of water, liquid beryllium fluoride and silica\nmelt are used to study the accuracy with which the entropy of ionic and\nmolecular liquids can be estimated from atom-atom radial distribution function\ndata. All three systems are known to display similar liquid-state thermodynamic\nand kinetic anomalies due to a region of anomalous excess entropy behaviour\nwhere entropy rises on isothermal compression. The pair correlation entropy is\ndemonstrated to be sufficiently accurate that the density-temperature regime of\nanomalous behaviour as well as the strength of the entropy anomaly can be\npredicted reliably for both ionic melts as well as different rigid-body pair\npotentials for water. Errors in the total thermodynamic entropy for ionic melts\ndue to the pair correlation approximation are of the order of 10% or less for\nmost state points but can be significantly larger in the anomalous regime at\nvery low temperatures. In the case of water, as expected given the rigid-body\nconstraints for a molecular liquids, the pair correlation approximation causes\nsignificantly larger errors, between 20 and 30%, for most state points.\nComparison of the excess entropy, Se, of ionic melts with the pair correlation\nentropy, S2, shows that the temperature dependence of Se is well described by T\n??2=5 scaling across both the normal and anomalous regimes, unlike in the case\nof S2. As a function of density, the Se(rho) curves shows only a single maximum\nwhile the S2(rho) curves show both a maximum and a minimum. These differences\nin the behaviour of S2 and Se are due to the fact that the residual\nmultiparticle entropy, delta(S) = Se - S2, shows a strong negative correlation\nwith tetrahedral order in the anomalous regime.",
        "positive": "Stability of liquid films covered by a carpet of self-propelled\n  surfactant particles: We consider a carpet of self-propelled particles at the liquid-gas interface\nof a liquid film on a solid substrate. The particles excert an excess pressure\non the interface and also move along the interface while the swimming direction\nperforms rotational diffusion. We study the intricate influence of these\nself-propelled insoluble surfactants on the stability of the film surface and\nshow that depending on the strength of in-surface rotational diffusion and the\nabsolute value of the in-surface swimming velocity several characteristic\ninstability modes can occur. In particular, rotational diffusion can either\nstabilize the film or induce instabilities of different character."
    },
    {
        "anchor": "On the thermodynamic consistency of Quasi-Linear Viscoelastic models for\n  soft solids: Originating in the field of biomechanics, Fung's model of quasi-linear\nviscoelasticity (QLV) is one of the most popular constitutive theories employed\nto compute the time-dependent relationship between stress and deformation in\nsoft solids. It is one of the simplest models of nonlinear viscoelasticity,\nbased on a time-domain integral formulation. In the present study, we consider\nthe QLV model incorporating a single scalar relaxation function. We provide\nnatural internal variables of state, as well as a consistent expression of the\nfree energy to illustrate the thermodynamic consistency of this version of the\nQLV model. The thermodynamic formulation highlights striking similarities\nbetween QLV and the internal-variable models introduced by Holzapfel and Simo.\nFinally, the dissipative features of compressible QLV materials are illustrated\nin simple tension.",
        "positive": "Thermotropic reentrant isotropy and antiferroelectricity in the\n  ferroelectric nematic realm: Comparing RM734 and DIO: The current intense study of ferroelectric nematic liquid crystals was\ninitiated by the observation of the same ferroelectric nematic phase in two\nindependently discovered organic rod-shaped mesogenic compounds, RM734 and DIO.\nWe recently reported that the compound RM734 also exhibits a monotropic,\nlow-temperature, antiferroelectric phase having reentrant isotropic symmetry\n(the $I_A$ phase), the formation of which is facilitated to a remarkable degree\nby doping with small (below $1\\%$) amounts of the ionic liquid ${\\rm\nBMIM-PF}_6$. Here we report similar phenomenology in DIO, showing that this\nreentrant isotropic behavior is not only a property of RM734 but is rather a\nmore general, material-independent feature of ferroelectric nematic mesogens.\nWe find that the reentrant isotropic phases observed in RM734 and DIO are\nsimilar but not identical, adding two new phases to the ferroelectric nematic\nrealm. The two $I_A$ phases exhibit similar, strongly peaked, diffuse x-ray\nscattering in the WAXS range $(1<q<2 \\, \\AA^{-1})$ indicative of a distinctive\nmode of short-ranged, side-by-side molecular packing. The scattering of the\n$I_A$ phases at small $q$ is quite different in the two materials, however,\nwith RM734 exhibiting a strong, single, diffuse peak at $q \\sim 0.08 \\,\\AA\n^{-1}$ indicating mesoscale modulation with $\\sim 80 \\,\\AA$ periodicity, and\nDIO a sharper diffuse peak at $q \\sim 0.27 \\,\\AA ^{-1} \\sim (2\\pi/{\\rm\nmolecular length})$, with second and third harmonics, indicating that in the\n$I_A$ phase of DIO, short-ranged molecular positional correlation is smectic\nlayer-like."
    },
    {
        "anchor": "Rheology of Weakly Vibrated Granular Media: We probe the rheology of weakly vibrated granular flows as function of flow\nrate, vibration strength and pressure by performing experiments in a vertically\nvibrated split-bottom shear cell. For slow flows, we establish the existence of\na novel vibration dominated granular flow regime, where the driving stresses\nsmoothly vanish as the driving rate is diminished. We distinguish three\nqualitatively different vibration dominated rheologies, most strikingly a\nregime where the shear stresses no longer are proportional to the pressure.",
        "positive": "Contraction of polymer gels created by the activity of molecular motors: We propose a theory based on non-equilibrium thermodynamics to describe the\nmechanical behavior of an active polymer gel created by the inclusion of\nmolecular motors in its solvent. When activated, these motors attach to the\nchains of the polymer network and shorten them creating a global contraction of\nthe gel, which mimics the active behavior of a cytoskeleton. The power\ngenerated by these motors is obtained by ATP hydrolysis reaction, which\ntransduces chemical energy into mechanical work. The latter is described by an\nincrement of strain energy in the gel due to an increased stiffness. This\neffect is described with an increment of the cross-link density in the polymer\nnetwork, which reduces its entropy. The theory then considers polymer network\nswelling and species diffusion to describe the transient passive behavior of\nthe gel. We finally formulate the problem of uniaxial contraction of a slab of\ngel and compare the results with experiments, showing good agreement."
    },
    {
        "anchor": "Coherent and Incoherent Dynamic Structure Function of the Free Fermi Gas: A detailed calculation of the coherent and incoherent dynamic structure\nfunctions of the free Fermi gas, starting from their expressions in terms of\nthe one- and semi-diagonal two-body density matrices, is derived and discussed.\nTheir behavior and evolution with the momentum transfer is analyzed, and\nparticular attention is devoted to the contributions that both functions\npresent at negative energies. Finally, an analysis of the energy weighted sum\nrules satisfied by both responses is also performed. Despite of the simplicity\nof the model, some of the conclusions can be extended to realistic systems.",
        "positive": "Simulating Thin Sheets: Buckling, Wrinkling, Folding and Growth: Numerical simulations of thin sheets undergoing large deformations are\ncomputationally challenging. Depending on the scenario, they may spontaneously\nbuckle, wrinkle, fold, or crumple. Nature's thin tissues often experience\nsignificant anisotropic growth, which can act as the driving force for such\ninstabilities. We use a recently developed finite element model to simulate the\nrich variety of nonlinear responses of Kirchhoff-Love sheets. The model uses\nsubdivision surface shape functions in order to guarantee convergence of the\nmethod, and to allow a finite element description of anisotropically growing\nsheets in the classical Rayleigh-Ritz formalism. We illustrate the great\npotential in this approach by simulating the inflation of airbags, the buckling\nof a stretched cylinder, as well as the formation and scaling of wrinkles at\nfree boundaries of growing sheets. Finally, we compare the folding of spatially\nconfined sheets subject to growth and shrinking confinement to find that the\ntwo processes are equivalent."
    },
    {
        "anchor": "Stability of parallel/perpendicular domain boundaries in lamellar block\n  copolymers under oscillatory shear: We introduce a model constitutive law for the dissipative stress tensor of\nlamellar phases to account for low frequency and long wavelength flows. Given\nthe uniaxial symmetry of these phases, we argue that the stress tensor must be\nthe same as that of a nematic but with the local order parameter being the\nslowly varying lamellar wavevector. This assumption leads to a dependence of\nthe effective dynamic viscosity on orientation of the lamellar phase. We then\nconsider a model configuration comprising a domain boundary separating\nlaterally unbounded domains of so called parallel and perpendicularly oriented\nlamellae in a uniform, oscillatory, shear flow, and show that the configuration\ncan be hydrodynamically unstable for the constitutive law chosen. It is argued\nthat this instability and the secondary flows it creates can be used to infer a\npossible mechanism for orientation selection in shear experiments.",
        "positive": "Pinning effects in a two-dimensional cluster glass: We study numerically the glass formation and depinning transition of a system\nof two-dimensional cluster-forming monodisperse particles in presence of\npinning disorder. The pairwise interaction potential is nonmonotonic, and is\nmotivated by the intervortex forces in type-$1.5$ superconductors. Such systems\ncan form cluster glasses due to the intervortex interactions following a\nthermal quench, without underlying disorder. We study the effects of vortex\npinning in these systems. We find that a small density of pinning centers of\nmoderate depth has limited effect on vortex glass formation, i.e., formation of\nvortex glasses is dominated by intervortex interactions. At higher densities\npinning can significantly affect glass formation. The cluster glass depinning,\nunder a constant driving force, is found to be plastic, with features distinct\nfrom non-cluster-forming systems such as clusters merging and breaking. We find\nthat in general vortices with cluster-forming interaction forces can exhibit\nstronger pinning effects than regular vortices."
    },
    {
        "anchor": "Dynamic Looping of a Free-Draining Polymer: We revisit the celebrated Wilemski-Fixman (WF) treatment for the looping time\nof a free-draining polymer. The WF theory introduces a sink term into the\nFokker-Planck equation for the $3(N+1)$-dimensional Ornstein-Uhlenbeck process\nof the polymer dynamics, which accounts for the appropriate boundary condition\ndue to the formation of a loop. The assumption for WF theory is considerably\nrelaxed. A perturbation method approach is developed that justifies and\ngeneralizes the previous results using either a Delta sink or a Heaviside sink.\nFor both types of sinks, we show that under the condition of a small\ndimensionless $\\epsilon$, the ratio of capture radius to the Kuhn length, we\nare able to systematically produce all known analytical and asymptotic results\nobtained by other methods. This includes most notably the transition regime\nbetween the $N^2$ scaling of Doi, and $N\\sqrt{N}/\\epsilon$ scaling of Szabo,\nSchulten, and Schulten. The mathematical issue at play is the non-uniform\nconvergence of $\\epsilon\\to 0$ and $N\\to\\infty$, the latter being an inherent\npart of the theory of a Gaussian polymer. Our analysis yields a novel term in\nthe analytical expression for the looping time with small $\\epsilon$, which is\npreviously unknown. Monte Carlo numerical simulations corroborate the\nanalytical findings. The systematic method developed here can be applied to\nother systems modeled by multi-dimensional Smoluchowski equations.",
        "positive": "Defect configurations and dynamical behavior in a Gay-Berne nematic\n  emulsion: To model a nematic emulsion consisting of a surfactant-coated water droplet\ndispersed in a nematic host, we performed a molecular dynamics simulation of a\ndroplet immersed in a system of 2048 Gay-Berne ellipsoids in a nematic phase.\nStrong radial anchoring at the surface of the droplet induced a Saturn ring\ndefect configuration, consistent with theoretical predictions for very small\ndroplets. A surface ring configuration was observed for lower radial anchoring\nstrengths, and a pair of point defects was found near the poles of the droplet\nfor tangential anchoring. We also simulated the falling ball experiment and\nmeasured the drag force anisotropy, in the presence of strong radial anchoring\nas well as zero anchoring strength."
    },
    {
        "anchor": "On the pearl size of hydrophobic polyelectrolytes: Hydrophobic polyelectrolytes have been predicted to adopt an unique\npearl-necklace conformation in aqueous solvents. We present in this Letter an\nattempt to characterise quantitatively this conformation with a focus on $D_p$,\nthe pearl size. For this purpose polystyrenesulfonate (PSS) of various\neffective charge fractions $f_{eff}$ and chain lengths $N$ has been adsorbed\nonto oppositely charged surfaces immersed in water in condition where the bulk\nstructure is expected to persist in the adsorbed state. \\emph{In situ}\nellipsometry has provided an apparent thickness $h_{app}$ of the PSS layer. In\nthe presence of added salts, we have found: $h_{app}\\sim aN^{0}f_{eff}^{-2/3}$\n($a$ is the monomer size) in agreement with the scaling predictions for $D_p$\nin the pearl-necklace model if one interprets $h_{app}$ as a measure of the\npearl size. At the lowest charge fractions we have found $h_{app}\\sim aN^{1/3}$\nfor the shorter chains, in agreement with a necklace/globule transition.",
        "positive": "Viscoelasticity characterization of compressible soft matter via\n  fluid-mediated dynamic interactions: Characterizing the softness of deformable materials having partial elastic\nand partial viscous behaviour via soft lubrication experiments has emerged as a\nversatile and robust methodology in recent times. However, a straightforward\nextension of the classical elastohydrodynamic lubrication theory that is\ncommonly employed for characterizing elastic materials turns out to be rather\ninadequate in explaining the response of such viscoelastic materials subjected\nto dynamic loading conditions, despite adhering to a mathematically acceptable\nframework via the complex Young's modulus as a material property. This deficit\nstems from a non-trivial interplay of the material compressibility and its\ntime-dependent dynamic response under fluid-mediated oscillatory loading\ntypical to surface probing experiments. Here we develop a soft-lubrication\nbased theoretical framework that enables the consistent recovery of\nviscoelastic model properties of materials from experimental data, independent\nof the specific loading condition. A major advancement here is the\nrectification of inconsistencies in viscoelasticity characterization of\npreviously reported models that are typically manifested by unphysical\ndependencies of the model parameters on the substrate layer thickness and the\noscillation frequency of the surface probing apparatus. Our results provide\nfurther pointers towards the design of characterization experiments for\nconsistent and specific mapping of the experimental data with the parametric\nvalues of the chosen material-model. These findings appear to be imperative in\ndesigning and selecting materials for emerging bio-engineering tools including\norgan-on-a-chip and human body-on-a-chip."
    },
    {
        "anchor": "Theoretical limits in detachment strength for axisymmetric bi-material\n  adhesives: Dry adhesives rely on short-ranged intermolecular bonds, hence requiring a\nlow elastic modulus to conform to the surface roughness of the adhered\nmaterial. Under external loads, however, soft adhesives accumulate strain\nenergy, which release drives the propagation of interfacial flaws prompting\ndetachment. The ideal adhesive is then soft but rigid. The solution to this\ncontroversial requirement is a bi-material adhesive having a soft tip, for\nsurface conformation, and a rigid backing, for reduced strain energy release,\nhence, better adhesive strength. This design strategy is widely observed in\nnature across multiple species. However, the detachment mechanisms of these\nadhesives are poorly understood and quantitative analysis of their adhesive\nstrength is still missing. Based on linear elastic fracture mechanics, we\nanalyze the strength of axisymmetric bi-material adhesives. We observed two\nmain detachment mechanisms, namely (i) center crack propagation and (ii) edge\ncrack propagation. If the soft tip is sufficiently thin, mechanism (i)\ndominates and provides stable crack propagation, thereby toughening the\ninterface. We ultimately provide the maximum theoretical strength of these\nadhesives obtaining closed form estimates for the detachment stress independent\nof the crack size, rendering the interface flaw tolerant.",
        "positive": "Spontaneous velocity alignment of Brownian particles with\n  feedback-induced propulsion: Based on Brownian dynamics simulations we study the collective behavior of a\ntwodimensional system of repulsively interacting colloidal particles, where\neach particle is propelled by a repulsive feedback force with time delay\n$\\tau$. Although the pair interactions are purely isotropic we observe a\nspontaneous, large-scale alignment of the velocity vectors. This phenomenon\npersists for long times and occurs in the absence of steady-state clustering.\nWe explain our observations by a combination of the effect of steric\ninteractions yielding local velocity ordering, and the effect of time delay,\nthat generates cluster dissolution, velocity persistence and velocity alignment\nover large distances. Overall, the behavior reveals intriguing similarities,\nbut also differences, to that observed in models of active matter, such as\nactive Brownian particles and the Vicsek model."
    },
    {
        "anchor": "Residual Stresses in Glasses: The history dependence of the glasses formed from flow-melted steady states\nby a sudden cessation of the shear rate $\\dot\\gamma$ is studied in colloidal\nsuspensions, by molecular dynamics simulations, and mode-coupling theory. In an\nideal glass, stresses relax only partially, leaving behind a finite persistent\nresidual stress. For intermediate times, relaxation curves scale as a function\nof $\\dot\\gamma t$, even though no flow is present. The macroscopic stress\nevolution is connected to a length scale of residual liquefaction displayed by\nmicroscopic mean-squared displacements. The theory describes this history\ndependence of glasses sharing the same thermodynamic state variables, but\ndiffering static properties.",
        "positive": "Polymers in crowded environment under stretching force: globule-coil\n  transitions: We study flexible polymer macromolecules in a crowded (porous) environment,\nmodelling them as self-attracting self-avoiding walks (SASAW) on site-diluted\npercolative lattices in space dimensions d=2, 3. The influence of stretching\nforce on the polymer folding and properties of globule-coil transitions are\nanalyzed. Applying the pruned-enriched Rosenbluth chain-growth method (PERM),\nwe estimate the transition temperature T_{\\Theta} between collapsed and\nextended polymer configurations and construct the phase diagrams of the\nglobule-coil coexistence when varying temperature and stretching force. The\ntransition to a completely stretched state, caused by applying force, is\ndiscussed as well."
    },
    {
        "anchor": "Viscous-inertial transition in dense granular suspension: Granular suspensions present a transition from a Newtonian rheology in the\nStokes limit to a Bagnoldian rheology when inertia is increased. A custom\nrheometer which can be run in a pressure or a volume-imposed mode is used to\nexamine this transition in the dense regime close to jamming. By varying\nsystematically the interstitial fluid, shear rate, and packing fraction in\nvolume-imposed measurements, we show that the transition takes place at a\nStokes number of 10 independent of the packing fraction. Using pressure-imposed\nrheometry, we investigate whether the inertial and viscous regimes can be\nunified as a function of a single dimensionless number based on stress\nadditivity.",
        "positive": "Adsorption Phenomena at Organic-Inorganic Interfaces: The qualitative solvent- and temperature-dependent conformational behavior of\na peptide in the proximity of solid substrates with different adsorption\nproperties is investigated by means of a simple lattice model. The resulting\npseudophase diagrams exhibit a complex structure, which can be understood by\nanalysing the minima of the free-energy landscape in dependence of appropriate\nsystem parameters."
    },
    {
        "anchor": "Trapping and transmission of matter-wave solitons in a collisionally\n  inhomogeneous environment: We investigate bright matter-wave solitons in the presence of a spatially\nvarying scattering length. It is demonstrated that, even in the absence of any\nexternal trapping potential, a soliton can be confined due to the inhomogeneous\ncollisional interactions. Moreover we observe the enhanced transmission of\nmatter-wave solitons through potential barriers for suitably chosen spatial\nvariations of the scattering length. The results indicate that the manipulation\nof atomic interactions can become a versatile tool to control the dynamics of\nmatter waves.",
        "positive": "Crystallization Dynamics on Curved Surfaces: We study the evolution from a liquid to a crystal phase in two-dimensional\ncurved space. At early times, while crystal seeds grow preferentially in\nregions of low curvature, the lattice frustration produced in regions with high\ncurvature is rapidly relaxed through isolated defects. Further relaxation\ninvolves a mechanism of crystal growth and defect annihilation where regions\nwith high curvature act as sinks for the diffusion of domain walls. The pinning\nof grain boundaries at regions of low curvature leads to the formation of a\nmetastable structure of defects, characterized by asymptotically slow dynamics\nof ordering and activation energies dictated by the largest curvatures of the\nsystem. These glassy-like ordering dynamics may completely inhibit the\nappearance of the ground state structures."
    },
    {
        "anchor": "Decompaction-wave propagation in a vibrated fine powder bed: We experimentally study the crack formation and decompaction-wave propagating\nin a vibrated powder bed consisting of glass beads of 5 {\\mu}m in diameter. The\nvibrated powder bed exhibits three distinct phases depending on the vibration\nconditions: consolidation (CS), static fracture (SF), and dynamic fracture\n(DF). Particularly, we found an upward wave propagation in the DF regime when\nthe powder bed is strongly vibrated. As a remarkable feature, we found that in\nfine cohesive powders, the decompaction-wave propagation speed normalized to\ngravitational speed is independent of the shaking strength. This result implies\nthat the wave propagation speed is governed by the balance between gravity and\ncohesion effect rather than vibration strength. We also explore the\nuniversality of wave propagation phenomenon in coarser and low-density granular\npowders.",
        "positive": "Quantifying the non-equilibrium activity of an active colloid: Active matter systems exhibit rich emergent behavior due to constant\ninjection and dissipation of energy at the level of individual agents. Since\nthese systems are far from equilibrium, their dynamics and energetics cannot be\nunderstood using the framework of equilibrium statistical mechanics. Recent\ndevelopments in stochastic thermodynamics extend classical concepts of work,\nheat, and energy dissipation to fluctuating non-equilibrium systems. We use\nrecent advances in experiment and theory to study the non-thermal dissipation\nof individual light-activated self-propelled colloidal particles. We focus on\ncharacterizing the transition from thermal to non-thermal fluctuations and show\nthat energy dissipation rates on the order of $\\sim k_BT/$s are measurable from\nfinite time series data."
    },
    {
        "anchor": "Structural and dynamical properties of nanoconfined supercooled water: Bulk water presents a large number of crystalline and amorphous ices.\nHydrophobic nanoconfinement is known to affect the tendency of water to form\nice and to reduce the melting temperature. However, a systematic study of the\nice phases in nanoconfinement is hampered by the computational cost of\nsimulations at very low temperatures. Here we develop a coarse-grained model\nfor a water monolayer in hydrophobic nanoconfinement and study the formation of\nice by Mote Carlo simulations. We find two ice phases: low-density-crystal ice\nat low pressure and high-density hexatic ice at high pressure, an intermediate\nphase between liquid and high-density-crystal ice.",
        "positive": "Compression induced folding of a sheet: an integrable system: The apparently intractable shape of a fold in a compressed elastic film lying\non a fluid substrate is found to have an exact solution. Such systems buckle at\na nonzero wavevector set by the bending stiffness of the film and the weight of\nthe substrate fluid. Our solution describes the entire progression from a\nweakly displaced sinusoidal buckling to a single large fold that contacts\nitself. The pressure decrease is exactly quadratic in the lateral displacement.\nWe identify a complex wavevector whose magnitude remains invariant with\ncompression."
    },
    {
        "anchor": "Proline isomerization regulates the phase behavior of elastin-like\n  polypeptides in water: Responsiveness of polypeptides and polymers in aqueous solution plays an\nimportant role in biomedical applications and in designing advanced functional\nmaterials. Elastin-like polypeptides (ELPs) are a well-known class of synthetic\nintrinsically disordered proteins (IDPs), which exhibit a lower critical\nsolution temperature (LCST) in pure water. The LCST transition can be further\ntuned by proline isomerization. Here, we study and compare the influence of\ncis/trans proline isomerization on the collapse of single ELPs in aqueous\nsolution. Our results reveal that cis isomers play an important role in tuning\nthe phase behavior of ELPs by hindering peptide-water hydrogen bonding while\npromoting intramolecular interactions.",
        "positive": "Allometric scaling law and ergodicity breaking in the vascular system: Allometry or the quantitative study of the relationship of body size to\nliving organism physiology is an important area of biophysical scaling\nresearch. The West-Brown-Enquist (WBE) model of fractal branching in a vascular\nnetwork explains the empirical allometric Kleiber law (the 3/4 scaling exponent\nfor metabolic rates as a function of animal's mass). The WBE model raises a\nnumber of new questions, such as how to account for capillary phenomena more\naccurately and what are more realistic dependencies for blood flow velocity on\nthe size of a capillary. We suggest a generalized formulation of the branching\nmodel and investigate the ergodicity in the fractal vascular system. In\ngeneral, the fluid flow in such a system is not ergodic, and ergodicity\nbreaking is attributed to the fractal structure of the network. Consequently,\nthe fractal branching may be viewed as a source of ergodicity breaking in\nbiophysical systems, in addition to such mechanisms as aging and macromolecular\ncrowding. Accounting for non-ergodicity is important for a wide range of\nbiomedical applications where long observations of time series are impractical.\nThe relevance to microfluidics applications is also discussed."
    },
    {
        "anchor": "Isotropic-nematic transition in liquid crystals confined between rough\n  walls: The effect of rough walls on the phase behaviour of a confined liquid crystal\n(LC) fluid is studied using constant pressure Monte Carlo simulations. The LC\nis modelled as a fluid of soft ellipsoidal molecules and the rough walls are\nrepresented as a hard wall with a number of molecules randomly embedded in\nthem. It is found that the isotropic-nematic (IN) transition is shifted to\nhigher pressures for rougher walls.",
        "positive": "Elastic Cheerios effect: self-assembly of cylinders on a soft solid: A rigid cylinder placed on a soft gel deforms its surface. When multiple\ncylinders are placed on the surface, they interact with each other via the\ntopography of the deformed gel which serves as an energy landscape; as they\nmove, the landscape changes which in turn changes their interaction. We use a\ncombination of experiments, simple scaling estimates and numerical simulations\nto study the self-assembly of cylinders in this elastic analog of the Cheerios\neffect for capillary interactions on a fluid interface. Our results show that\nthe effective two body interaction can be well described by an exponential\nattraction potential as a result of which the dynamics also show an exponential\nbehavior with respect to the separation distance. When many cylinders are\nplaced on the gel, the cylinders cluster together if they are not too far\napart; otherwise their motion gets elastically arrested."
    },
    {
        "anchor": "Multi-plectoneme phase of double-stranded DNA under torsion: We use the worm-like chain model to study supercoiling of DNA under tension\nand torque. The model reproduces experimental data for a broad range of forces,\nsalt concentrations and contour lengths. We find a plane of first order phase\ntransitions ending in a smeared out line of critical points, the\nmulti-plectoneme phase, which is characterized by a fast twist mediated\ndiffusion of plectonemes and a torque that rises after plectoneme formation\nwith increasing linking number. The discovery of this new phase at the same\ntime resolves the discrepancies between existing models and experiment.",
        "positive": "Active nematics with deformable particles: The hydrodynamic theory of active nematics has been often used to describe\nthe spatio-temporal dynamics of cell flows and motile topological defects\nwithin soft confluent tissues. Those theories, however, often rely on the\nassumption that tissues consist of cells with a fixed, anisotropic shape and do\nnot resolve dynamical cell shape changes due to flow gradients. In this paper\nwe extend the continuum theory of active nematics to include cell shape\ndeformability. We find that circular cells in tissues must generate sufficient\nactive stress to overcome an elastic barrier to deforming their shape in order\nto drive tissue-scale flows. Above this threshold the systems enter a dynamical\nsteady-state with regions of elongated cells and strong flows coexisting with\nquiescent regions of isotropic cells."
    },
    {
        "anchor": "Relaxation Dynamics in Persistent Epithelial Tissues: Cell monolayers and epithelial tissues display slow dynamics during the\nliquid-glass transitions, a phenomenon with direct relevance to embryogenesis,\ntumor metastases, and wound healing. In active cells, persistent motion and\ncell deformation compete, significantly influencing relaxation dynamics. Here,\nwe numerically construct the liquid-glass transition phase diagram for\ntwo-dimensional polydisperse persistent cells. We employ cage-relative measures\nand conduct extensive simulations to eliminate the influence of system size\neffects. These effects arise from long-wavelength fluctuations in nearly\nequilibrated cells and a combination of long-wavelength fluctuations and\nnon-equilibrium effects in highly persistent cells. Our study unveils\ndistinctive intermittent dynamics associated with intermittent T1 transitions\nin highly persistent cells, where the velocity correlates over space with a\ncharacteristic length $\\xi$. The $\\alpha$ relaxation time exhibits a universal\npower-law dependence on the irreversible T1 transition rate,\n$\\Gamma_{\\rm{T1}}^{\\rm irr}$, multiplied by ${\\rm exp}(\\xi)$. Here, $\\xi$\nvanishes in nearly equilibrated cells, and $\\Gamma_{\\rm{T1}}^{\\rm irr}$\ndiminishes towards the mode-coupling glass transition point.",
        "positive": "Topological interactions between ring polymers: Implications for\n  chromatin loops: Chromatin looping is a major epigenetic regulatory mechanism in higher\neukaryotes. Besides its role in transcriptional regulation, chromatin loops\nhave been proposed to play a pivotal role in the segregation of entire\nchromosomes. The detailed topological and entropic forces between loops still\nremain elusive. Here, we quantitatively determine the potential of mean force\nbetween the centers of mass of two ring polymers, i.e. loops. We find that the\ntransition from a linear to a ring polymer induces a strong increase in the\nentropic repulsion between these two polymers. On top, topological interactions\nsuch as the non-catenation constraint further reduce the number of accessible\nconformations of close-by ring polymers by about 50%, resulting in an\nadditional effective repulsion. Furthermore, the transition from linear to ring\npolymers displays changes in the conformational and structural properties of\nthe system. In fact, ring polymers adopt a markedly more ordered and aligned\nstate than linear ones. The forces and accompanying changes in shape and\nalignment between ring polymers suggest an important regulatory function of\nsuch a topology in biopolymers. We conjecture that dynamic loop formation in\nchromatin might act as a versatile control mechanism regulating and maintaining\ndifferent local states of compaction and order."
    },
    {
        "anchor": "Extraction a Formalism for Fluids with Non-Spherical Molecules based on\n  the Cluster Expansion of the Energy Functional: In this work, based on the cluster expansion of the energy functional, we\nhave extracted a formalism for calculation of the thermodynamic properties of\nfluids with non-spherical molecules. The salient feature of the extracted\nformalism is that it has no restrictions on the type of interaction. In fact\nour formalism can be employed for all types of realistic inter-particle\ninteractions. Here, for the interaction of two anisotropic molecules, we have\napplied the Gay-Berne potential. Finally, we have applied this formalism to\ncalculate some thermodynamic properties of fluid H_2 which shows some expected\nresults.",
        "positive": "Ordering Kinetics in the Active Model B: We undertake a detailed numerical study of the {\\it Active Model B} proposed\nby Wittkowski et al. [Nature Comm. {\\bf 5}, 4351 (2014)]. We find that the\nintroduction of activity has a drastic effect on the ordering kinetics. First,\nthe domain growth law shows a crossover from the usual Lifshitz-Slyozov growth\nlaw for phase separation ($L \\sim t^{1/3}$, where $t$ is the time) to a novel\ngrowth law ($L \\sim t^{1/4}$) at late times. Second, the correlation function\nexhibits dynamical scaling for a given activity strength $\\lambda$, but the\nscaling function depends on $\\lambda$."
    },
    {
        "anchor": "Electrostatic inactivation of RNA viruses at air-water and liquid-liquid\n  interfaces: Understanding the interactions between viruses and surfaces or interfaces is\nimportant, as they provide the principles underpinning the cleaning and\ndisinfection of contaminated surfaces. Yet, the physics of such interactions is\ncurrently poorly understood. For instance, there are longstanding experimental\nobservations suggesting that the presence of air-water interfaces can\ngenerically inactivate and kill viruses, yet the mechanism underlying this\nphenomenon remains unknown. Here we use theory and simulations to show that\nelectrostatics provides one such mechanism, and that this is very general.\nThus, we predict that the free energy of an RNA virus should increase by\nseveral thousands of $k_BT$ as the virion breaches an air-water interface. We\nalso show that the fate of a virus approaching a generic liquid-liquid\ninterface depends strongly on the detailed balance between interfacial and\nelectrostatic forces, which can be tuned, for instance, by choosing different\nmedia to contact a virus-laden respiratory droplet. We propose that these\nresults can be used to design effective strategies for surface disinfection.\nIntriguingly, tunability requires electrostatic and interfacial forces to scale\nsimilarly with viral size, which naturally occurs when charges are arranged in\na double-shell distribution as in RNA viruses like influenza and all\ncoronaviruses.",
        "positive": "A good and computationally efficient polynomial approximation to the\n  Maier-Saupe nematic free energy: A new computational strategy is proposed to approximate, with a simple but\naccurate expression, the Maier- Saupe free energy for nematic order. Instead of\nthe traditional approach of expanding the free energy with a truncated Taylor\nseries, we employ a least-squares fitting to obtain the coefficients of a\npolynomial expression. Both methods are compared, and the fitting with at most\nfive polynomial terms is shown to provide a satisfactory fitting, and to give\nmuch more accurate results than the traditional Taylor expansion. We perform\nthe analysis in terms of the tensor order parameter, so the results are valid\nin uniaxial and biaxial states."
    },
    {
        "anchor": "The difficulty of folding self-folding origami: Why is it difficult to refold a previously folded sheet of paper? We show\nthat even crease patterns with only one designed folding motion inevitably\ncontain an exponential number of `distractor' folding branches accessible from\na bifurcation at the flat state. Consequently, refolding a sheet requires\nfinding the ground state in a glassy energy landscape with an exponential\nnumber of other attractors of higher energy, much like in models of protein\nfolding (Levinthal's paradox) and other NP-hard satisfiability (SAT) problems.\nAs in these problems, we find that refolding a sheet requires actuation at\nmultiple carefully chosen creases. We show that seeding successful folding in\nthis way can be understood in terms of sub-patterns that fold when cut out\n(`folding islands'). Besides providing guidelines for the placement of active\nhinges in origami applications, our results point to fundamental limits on the\nprogrammability of energy landscapes in sheets.",
        "positive": "Topological signatures of globular polymers: Simulations in which a globular ring polymer with delocalized knots is\nseparated in two interacting loops by a slipping link, or in two\nnon-interacting globuli by a wall with a hole, show how the minimal crossing\nnumber of the knots controls the equilibrium statistics. With slipping link the\nring length is divided between the loops according to a simple law, but with\nunexpectedly large fluctuations. These are suppressed only for unknotted loops,\nwhose length distribution shows always a fast power law decay. We also discover\nand explain a topological effect interfering with that of surface tension in\nthe globule translocation through a membrane nanopore."
    },
    {
        "anchor": "Cohesive energy, stability and structural transitions in polyelectrolyte\n  bundles: A lattice of uniformly charged, infinitesimally thin, rods decorated with an\nordered array of counterions exhibits anomalous behavior as the spacing between\nthe rods is varied. In particular, the counterion lattice undergoes a sequence\nof structural shearing, or \"tilting,\" phase transformations as the spacing\nbetween the rods decreases. The potential implications of this behavior with\nrespect to the packaging of biologically relevant polyelectrolytic molecules\nare commented upon.",
        "positive": "Origin of Spatiotemporal Fluctuations in Discontinuous Shear Thickening: Rheological phase transitions open the door to the less explored realm of\nnon-equilibrium phase transitions. The main mechanism driving these transitions\nis usually mechanical perturbation by shear--- an unjamming mechanism.\nInvestigating discontinuous shear thickening (DST) is challenging because the\nshear counterintuitively acts as a jamming mechanism. Moreover, at the brink of\nthis transition, a thickening material exhibits fluctuations that extend both\nspatially and temporally. Despite recent extensive research, the origins of\nsuch spatiotemporal fluctuations remain unidentified. Here, we investigate\nlarge fluctuations in DST by using versatile tools of stochastic\nthermodynamics. We discover a non-equilibrium dichotomy in the underlying\nmechanisms that give rise to large fluctuations and demonstrate that this\ndichotomy is a manifestation of novel collective behaviors across the\ntransition. We then reveal the origin of spatiotemporal fluctuations in the\nshear thickening transition. Our study emphasizes the roles of stochastic\nthermodynamics tools in investigating non-equilibrium phase transitions, and\ndemonstrates that these transitions are accompanied by simple dichotomies. We\nexpect that our general approach will pave the way to unmasking the nature of\nnon-equilibrium phase transitions."
    },
    {
        "anchor": "A numerical study of one-patch colloidal particles: from square-well to\n  Janus: We perform numerical simulations of a simple model of one-patch colloidal\nparticles to investigate: (i) the behavior of the gas-liquid phase diagram on\nmoving from a spherical attractive potential to a Janus potential and (ii) the\ncollective structure of a system of Janus particles. We show that, for the case\nwhere one of the two hemispheres is attractive and one is repulsive, the system\norganizes into a dispersion of orientational ordered micelles and vesicles and,\nat low $T$, the system can be approximated as a fluid of such clusters,\ninteracting essentially via excluded volume. The stability of this cluster\nphase generates a very peculiar shape of the gas and liquid coexisting\ndensities, with a gas coexistence density which increases on cooling,\napproaching the liquid coexistence density at very low $T$.",
        "positive": "Shocks near Jamming: Non-linear sound is an extreme phenomenon typically observed in solids after\nviolent explosions. But granular media are different. Right when they jam,\nthese fragile and disordered solids exhibit a vanishing rigidity and sound\nspeed, so that even tiny mechanical perturbations form supersonic shocks. Here,\nwe perform simulations in which two-dimensional jammed granular packings are\ndynamically compressed, and demonstrate that the elementary excitations are\nstrongly non-linear shocks, rather than ordinary phonons. We capture the full\ndependence of the shock speed on pressure and impact intensity by a\nsurprisingly simple analytical model."
    },
    {
        "anchor": "On the different regimes of subaqueous transport: We review different aspects of subaqueous sediment transport. We discuss the\nstatic threshold and its dependency with longitudinal and transverse slopes, as\nwell as cohesion. We describe the different regimes of transport: erosion and\nmomentum limited bed load, and suspended load. In all these cases, we derive\nthe expressions of the saturation flux $q_{\\rm sat}$ and the saturation length\n$L_{\\rm sat}$ and discuss their dependencies.",
        "positive": "Learning to self-fold at a bifurcation: Disordered mechanical systems can deform along a network of pathways that\nbranch and recombine at special configurations called bifurcation points.\nMultiple pathways are accessible from these bifurcation points; consequently,\ncomputer-aided design algorithms have been sought to achieve a specific\nstructure of pathways at bifurcations by rationally designing the geometry and\nmaterial properties of these systems. Here, we explore an alternative physical\ntraining framework in which the topology of folding pathways in a disordered\nsheet is changed in a desired manner due to changes in crease stiffnesses\ninduced by prior folding. We study the quality and robustness of such training\nfor different `learning rules', that is, different quantitative ways in which\nlocal strain changes the local folding stiffness. We experimentally demonstrate\nthese ideas using sheets with epoxy-filled creases whose stiffnesses change due\nto folding before the epoxy sets. Our work shows how specific forms of\nplasticity in materials enable them to learn non-linear behaviors through their\nprior deformation history in a robust manner."
    },
    {
        "anchor": "Deforming Active Droplets in Viscoelastic Media: To mimic the motion of biological swimmers in bodily fluids, a novel\nexperimental system of micellar solubilization driven active droplets in a\nvisco-elastic polymeric solution is presented. The visco-elastic nature of the\nmedium, characterized by the Deborah number (De), is tuned by varying the\nsurfactant (fuel) and polymer concentration in the ambient medium. At moderate\nDe, the droplet exhibits a steady deformed shape, markedly different from the\nspherical shape observed in Newtonian media. A theoretical analysis based on\nthe normal stress balance at the interface is shown to accurately predict the\ndroplet shape. With a further increase in De, time-periodic deformations\naccompanied by oscillatory transitions in swimming modes are observed. The\nstudy unveils the rich complexity in the motion of active droplets in\nviscoelastic fluids, which has been hitherto unexplored.",
        "positive": "Influence of Chain Interdiffusion Between Immiscible Polymers on\n  Dewetting Dynamics: The interface between two immiscible polymers, polystyrene (PS) and\npolydimethylsiloxane (PDMS), was studied by neutron reflectivity and dewetting\nby using free PS chains and PDMS brushes. Unexpectedly, we found that the PS\nchains diffuse in the PDMS brushes at temperatures well below the glass\ntransition temperatures of PS, the dynamics being largely determined by the\ngrafting density of the brush. By this study, we demonstrate the major\ninfluence of the chains interdiffusion on the friction properties for a couple\nof immiscible polymers. By the way, the puzzling ageing of PS thin films\nobserved from dewetting experiments is found to be directly related to\nmodifications of the PS/PDMS interface."
    },
    {
        "anchor": "Towards interpreting the thermally activated $\u03b2$ dynamics in\n  metallic glass with the structural constraint neural network: Unraveling the structural factors influencing the dynamics of amorphous\nsolids is crucial. While deep learning aids in navigating these complexities,\ntransparency issues persist. Inspired by the successful application of\nprototype neural networks in the field of image analysis, this study introduces\na new machine-learning approach to tackle the interpretability challenges faced\nin glassy research. Distinguishing from traditional machine learning models\nthat only predict dynamics from the structural input, the adapted neural\nnetwork additionally tries to learn structural prototypes under various dynamic\npatterns in the training phase. Such learned structural constraints can serve\nas a breakthrough in explaining how structural differences impact dynamics. We\nfurther use the proposed model to explore the correlation between the local\nstructure and activation energy in the CuZr metallic glass. Building upon this\ninterpretable model, we demonstrated significant structural differences among\nparticles with distinct activation energies. The insights gained from this\nanalysis serve as a data-driven solution for unraveling the origins of the\nstructural heterogeneity in amorphous alloys, offering a valuable contribution\nto the understanding the amorphous materials.",
        "positive": "The Square-Shoulder-Asakura-Oosawa model: A new model for a colloidal size-asymmetric binary mixture is proposed: The\nSquare-Shoulder-Asakura-Oosawa. This belongs to the larger class of\nnon-additive hard-spheres models and has the property that its effective pair\nformulation is exact whenever the solvent particle fits inside the interstitial\nregion of three touching solute particles. Therefore one can study its\nproperties from the equivalent one-component effective problem. Some remarks on\nthe phase diagram of this new model are also addressed."
    },
    {
        "anchor": "A novel approach for modeling the non-Newtonian behavior of simple\n  liquids: application to liquid water viscosity from low to high shear rates: The aim of this paper is to present a modeling for the rheological behavior\nof simple liquids as a function of the amplitude of the imposed shear stress or\nstrain. The elastic mode theory (Ref. 6) is first generalized to take into\naccount the fact that during a flow experiment, mechanical energy is injected\nin a system initially at thermodynamic equilibrium. This generalized theory can\nbe seen as a particular aspect of the general problem of perturbation by the\nmeasurement, associated with that of the coupling between fluctuation and\ndissipation. This generalization leads to a \"finitary\" character of the model.\nIt is then combined with the inertial mode theory (Ref. 7). The formalism thus\nobtained allows to model the rheological behavior of liquids over a wide range\nof velocity gradients, including the intermediate narrow range corresponding to\nthe Newtonian regime. As experimental tests, viscosity measurements with two\nkinds of moving rotor rheometers were performed. Only data obtained with liquid\nwater at room temperature are presented and quantitatively analyzed here. It is\nalso shown that liquid n-octane exhibits the same qualitative behaviors as\nthose of liquid water. In the appendices, connection of this theory with\nquantum mechanics and turbulence phenomena are discussed, and the notion of\nviscous mass is introduced.",
        "positive": "Effects of particle stiffness on the extensional rheology of model\n  rod-like nanoparticle suspensions: The linear and nonlinear rheological behavior of two rod-like particle\nsuspensions as a function of concentration is studied using small amplitude\noscillatory shear, steady shear and capillary breakup extensional rheometry.\nThe rod-like suspensions are composed of fd virus and its mutant fdY21M, which\nare perfectly monodisperse, with a length on the order of 900 nm. The particles\nare semi flexible yet differ in their persistence length. The effect of\nstiffness on the rheological behavior in both, shear and extensional flow, is\ninvestigated experimentally. The linear viscoelastic shear data is compared in\ndetail with theoretical predictions for worm-like chains. The extensional\nproperties are compared to Batchelor's theory, generalized for the shear\nthinning nature of the suspensions. Theoretical predictions agree well with the\nmeasured complex moduli at low concentrations as well as the nonlinear shear\nand elongational viscosities at high flow rates. The results in this work\nprovide guidelines for enhancing the elongational viscosity based on purely\nfrictional effects in absence of strong normal forces which are characteristic\nfor high molecular weight polymers."
    },
    {
        "anchor": "Collective behavior of squirmers in thin films: Bacteria in biofilms form complex structures and can collectively migrate\nwithin mobile aggregates, which is referred to as swarming. This behavior is\ninfluenced by a combination of various factors, including morphological\ncharacteristics and propulsive forces of swimmers, their volume fraction within\na confined environment, and hydrodynamic and steric interactions between them.\nIn our study, we employ the squirmer model for microswimmers and the\ndissipative particle dynamics method for fluid modeling to investigate the\ncollective motion of swimmers in thin films. The film thickness permits a free\norientation of non-spherical squirmers, but constraints them to form a\ntwo-layered structure at maximum. Structural and dynamic properties of squirmer\nsuspensions confined within the slit are analyzed for different volume\nfractions of swimmers, motility types (e.g., pusher, neutral squirmer, puller),\nand the presence of a rotlet dipolar flow field, which mimics the\ncounter-rotating flow generated by flagellated bacteria. Different states are\ncharacterized, including a gas-like phase, swarming, and motility-induced phase\nseparation, as a function of increasing volume fraction. Our study highlights\nthe importance of an anisotropic swimmer shape, hydrodynamic interactions\nbetween squirmers, and their interaction with the walls for the emergence of\ndifferent collective behaviors. Interestingly, the formation of collective\nstructures may not be symmetric with respect to the two walls. Furthermore, the\npresence of a rotlet dipole significantly mitigates differences in the\ncollective behavior between various swimmer types. These results contribute to\na better understanding of the formation of bacterial biofilms and the emergence\nof collective states in confined active matter.",
        "positive": "Role of uncrosslinked chains in droplets dynamics on silicone elastomers: We report an unexpected behavior in wetting dynamics on soft silicone\nsubstrates: the dynamics of aqueous droplets deposited on vertical plates of\nsuch elastomers exhibits two successive speed regimes. This macroscopic\nobservation is found to be closely related to microscopic phenomena occurring\nat the scale of the polymer network: we show that uncrosslinked chains found in\nmost widely used commercial silicone elastomers are responsible for this\nsurprising behavior. A direct visualization of the uncrosslinked oligomers\ncollected by water droplets is performed, evidencing that a capillarity-induced\nphase separation occurs: uncrosslinked oligomers are extracted from the\nsilicone elastomer network by the water-glycerol mixture droplet. The sharp\nspeed change is shown to coincide with an abrupt transition in surface tension\nof the droplets, when a critical surface concentration in uncrosslinked\noligomer chains is reached. We infer that a droplet shifts to a second regime\nwith a faster speed when it is completely covered with a homogeneous oil film."
    },
    {
        "anchor": "Bogoliubov theory of the Hawking effect in Bose-Einstein condensates: Artificial black holes may demonstrate some of the elusive quantum properties\nof the event horizon, in particular Hawking radiation. One promising candidate\nis a sonic hole in a Bose-Einstein condensate. We clarify why Hawking radiation\nemerges from the condensate and how this condensed-matter analog reflects some\nof the intriguing aspects of quantum black holes.",
        "positive": "Thermodynamics, formation dynamics and structural correlations in the\n  bulk amorphous phase of the phase-field crystal model: We investigate bulk thermodynamic and microscopic structural properties of\namorphous solids in the framework of the phase-field crystal (PFC) model. These\nare metastable states with a non-uniform density distribution having no\nlong-range order. From extensive numerical simulations we determine the\ndistribution of free energy density values in varying size amorphous systems\nand also the point-to-set correlation length, which is the radius of the\nlargest volume of amorphous one can take while still having the particle\narrangements within the volume determined by the particle ordering at the\nsurface of the chosen volume. We find that in the thermodynamic limit, the free\nenergy density of the amorphous tends to a value that has a slight dependence\non the initial state from which it was formed -- i.e.\\ it has a formation\nhistory dependence. The amorphous phase is observed to form on both sides of\nthe liquid linear-stability limit, showing that the liquid to amorphous\ntransition is first order, with an associated finite free energy barrier when\nthe liquid is metastable. In our simulations this is demonstrated when noise in\nthe initial density distribution is used to induce nucleation events from the\nmetastable liquid. Depending on the strength of the initial noise, we observe a\nvariety of nucleation pathways, in agreement with previous results for the PFC\nmodel, and which show that amorphous precursor mediated multi-step crystal\nnucleation can occur in colloidal systems."
    },
    {
        "anchor": "Computational confirmation of scaling predictions for equilibrium\n  polymers: We report the results of extensive Dynamic Monte Carlo simulations of systems\nof self-assembled Equilibrium Polymers without rings in good solvent.\nConfirming recent theoretical predictions, the mean-chain length is found to\nscale as $\\Lav = \\Lstar (\\phi/\\phistar)^\\alpha \\propto \\phi^\\alpha \\exp(\\delta\nE)$ with exponents $\\alpha_d=\\delta_d=1/(1+\\gamma) \\approx 0.46$ and $\\alpha_s\n= [1+(\\gamma-1)/(\\nu d -1)]/2 \\approx 0.60, \\delta_s=1/2$ in the dilute and\nsemi-dilute limits respectively. The average size of the micelles, as measured\nby the end-to-end distance and the radius of gyration, follows a very similar\ncrossover scaling to that of conventional quenched polymer chains. In the\nsemi-dilute regime, the chain size distribution is found to be exponential,\ncrossing over to a Schultz-Zimm type distribution in the dilute limit. The very\nlarge size of our simulations (which involve mean chain lengths up to 5000,\neven at high polymer densities) allows also an accurate determination of the\nself-avoiding walk susceptibility exponent $\\gamma = 1.165 \\pm 0.01$.",
        "positive": "On mean-field theories of dynamics in supercooled liquids: We develop a hybrid numerical approach to extract the exact memory function\nK(t) of a tagged particle in three-dimensional glass-forming liquids. We\ncompare the behavior of the exact memory kernel to two mean-field approaches,\nnamely the standard mode-coupling theory and a recently proposed ansatz for the\nmemory function that forms the basis of a new derivation of the exact form of\nK(t) for a fluid with short-ranged interactions in infinite dimensions. Each of\nthe mean-field functions qualitatively and quantitatively share traits with the\nexact K(t), although several important quantitative differences are manifest."
    },
    {
        "anchor": "Kelvin-Helmholtz instabilities across periodic plates: We consider the linear stability of two inviscid fluids, in the presence of\ngravity, sheared past each other and separated by an flexible plate. Conditions\nfor exponential growth of velocity perturbations are found as functions of the\nflexural rigidity of the plate and the shear rate. This Kelvin-Helmholtz\ninstability is then analysed in the presence of plates with spatially periodic\n(with period $a$) flexural rigidity arising from, for example, a periodic\nmaterial variation. The eigenvalues of this periodic system are computed using\nBloch's Theorem (Floquet Theory) that imposes specific Fourier decompositions\nof the velocity potential and plate deformations. We derive the nonhermitian\nmatrix whose eigenvalues determine the dispersion relation. Our dispersion\nrelation shows that plate periodicity generally destabilises the flow, compared\nto a uniform plate with the same mean flexural rigidity. However, enhanced\ndestabilisation and stabilization can occur for disturbances with wavelengths\nnear an even multiple of the plate periodicity. The sensitivity of flows with\nsuch wavelengths arises from the nonpropagating, ``Bragg reflected'' modes\ncoupled to the plate periodicity through the boundary condition at the plate.",
        "positive": "Dissipative Effects in the Electronic Transport through DNA Molecular\n  Wires: We investigate the influence of a dissipative environment which effectively\ncomprises the effects of counterions and hydration shells, on the transport\nproperties of short \\DNA wires. Their electronic structure is captured by a\ntight-binding model which is embedded in a bath consisting of a collection of\nharmonic oscillators. Without coupling to the bath a temperature independent\ngap opens in the electronic spectrum. Upon allowing for electron-bath\ninteraction the gap becomes temperature dependent. It increases with\ntemperature in the weak-coupling limit to the bath degrees of freedom. In the\nstrong-coupling regime a bath-induced {\\it pseudo-gap} is formed. As a result,\na crossover from tunneling to activated behavior in the low-voltage region of\nthe $I$-$V$ characteristics is observed with increasing temperature. The\ntemperature dependence of the transmission near the Fermi energy, $t(E_{\\rm\nF})$, manifests an Arrhenius-like behavior in agreement with recent transport\nexperiments. Moreover, $t(E_{\\rm F})$ shows a weak exponential dependence on\nthe wire length, typical of strong incoherent transport. Disorder effects smear\nthe electronic bands, but do not appreciably affect the pseudo-gap formation."
    },
    {
        "anchor": "$1/f$ noise on the brink of wet granular melting: The collective behavior of a two-dimensional wet granular cluster under\nhorizontal swirling motions is investigated experimentally. Depending on the\nbalance between the energy injection and dissipation, the cluster evolves into\nvarious nonequilibrium stationary states with strong internal structure\nfluctuations with time. Quantitative characterizations of the fluctuations with\nthe bond orientational order parameter $q_{\\rm 6}$ reveal power spectra of the\nform $f^{\\alpha}$ with the exponent $\\alpha$ closely related to the stationary\nstates of the system. In particular, $1/f$ type of noise with $\\alpha\\approx-1$\nemerges as melting starts from the free surface of the cluster, suggesting the\npossibility of using $1/f$ noise as an indicator for phase transitions in\nsystems driven far from thermodynamic equilibrium.",
        "positive": "A simplified particulate model for coarse-grained hemodynamics\n  simulations: Human blood flow is a multi-scale problem: in first approximation, blood is a\ndense suspension of plasma and deformable red cells. Physiological vessel\ndiameters range from about one to thousands of cell radii. Current\ncomputational models either involve a homogeneous fluid and cannot track\nparticulate effects or describe a relatively small number of cells with high\nresolution, but are incapable to reach relevant time and length scales. Our\napproach is to simplify much further than existing particulate models. We\ncombine well established methods from other areas of physics in order to find\nthe essential ingredients for a minimalist description that still recovers\nhemorheology. These ingredients are a lattice Boltzmann method describing rigid\nparticle suspensions to account for hydrodynamic long range interactions\nand---in order to describe the more complex short-range behavior of\ncells---anisotropic model potentials known from molecular dynamics simulations.\nPaying detailedness, we achieve an efficient and scalable implementation which\nis crucial for our ultimate goal: establishing a link between the collective\nbehavior of millions of cells and the macroscopic properties of blood in\nrealistic flow situations. In this paper we present our model and demonstrate\nits applicability to conditions typical for the microvasculature."
    },
    {
        "anchor": "Field-Dependent Tilt and Birefringence of Electroclinic Liquid Crystals:\n  Theory and Experiment: An unresolved issue in the theory of liquid crystals is the molecular basis\nof the electroclinic effect in the smectic-A phase. Recent x-ray scattering\nexperiments suggest that, in a class of siloxane-containing liquid crystals, an\nelectric field changes a state of disordered molecular tilt in random\ndirections into a state of ordered tilt in one direction. To investigate this\nissue, we measure the optical tilt and birefringence of these liquid crystals\nas functions of field and temperature, and we develop a theory for the\ndistribution of molecular orientations under a field. Comparison of theory and\nexperiment confirms that these materials have a disordered distribution of\nmolecular tilt directions that is aligned by an electric field, giving a large\nelectroclinic effect. It also shows that the net dipole moment of a correlated\nvolume of molecules, a key parameter in the theory, scales as a power law near\nthe smectic-A--smectic-C transition.",
        "positive": "Simulating phase transitions by means of quasi static state changes: the\n  capabilities of the time dependent Van der Waals equation of state: The Van der Waals equation (VdW-EoS) is a prototype equation of state for\nrealistic systems, because it contains the excluded volume and the particle\ninteractions. Additionally, the simulated annealing (and the similar simulated\ncompressing) approach applies the time dependence on to one of the variables of\nstate to simulate quasi static state changes. The combination of both enables\nthe simulation of time dependent processes like phase transitions of\nsubcritical, critical and supercritical substances on every arbitrary condition\nincluding a passage over points of singularity of the corresponding\nsusceptibility coefficients. This is achieved by a new simulation approach\ncalled simulated expansion. This approach makes the simulation comparable to\nnatural processes which exhibit gradual changes in volume, rather than changes\nin temperature or pressure, as exercised in simulated annealing or compressing.\nThe demonstrated method here serves as a blue print for more general classes of\nsimulation approaches."
    },
    {
        "anchor": "Phase Behavior of the Patchy Colloids Confined in the Patchy Porous\n  Media: A simple model for functionalized disordered porous media is proposed and the\neffects of confinement on self-association, percolation and phase behavior of a\nfluid of patchy particles are studied. The media is formed by a randomly\ndistributed hard-sphere obstacles fixed in space and decorated by a certain\nnumber of off-center square-well sites. The properties of the fluid of patchy\nparticles, represented by the fluid of hard spheres each bearing a set of the\noff-center square-well sites, are studied using an appropriate combination of\nthe scaled particle theory for the porous media, Wertheim's thermodynamic\nperturbation theory, and the Flory-Stockmayer theory. To assess the accuracy of\nthe theory a set of computer simulations have been performed. In general,\npredictions of the theory appear to be in a good agreement with computer\nsimulation results. Confinement and competition between the formation of bonds\nconnecting the fluid particles, and connecting fluid particles and obstacles of\nthe matrix, give rise to a re-entrant phase behavior with three critical points\nand two separate regions of the liquid-gas phase coexistence.",
        "positive": "Growth-Collapse Cycles of a Bose-Einstein Condensate with Attractive\n  Interactions: A Bose-Einstein condensate of atoms with attractive interactions exhibits\ngrowth and collapse cycles, when it is fed by a thermal cloud. Recently this\nphenomenon has been directly observed in a trapped Li-7 gas. We offer a\nquantitative explanation of the data, on the basis of a model proposed earlier.\nIt is shown that the condensate wave function acquires a chaotic component\nafter the first collapse, indicating superfluid turbulence."
    },
    {
        "anchor": "Tunnel magnetoresistance of polymeric chains: Coherent spin-dependent electronic transport is investigated in a molecular\njunction made of polymeric chain attached to ferromagnetic electrodes (Ni and\nCo, respectively). Molecular system is described by a simple Huckel model,\nwhile the coupling to the electrodes is treated through the use of a broad-band\ntheory. The current flowing through the device is calculated within\nnon-equilibrium Green's function approach. It is shown that tunnel\nmagnetoresistance of molecular junction can be quite large (over 100 %)and\nstrongly depends on: (i) the lenght of the polymeric chain and (ii) the\nstrength of the molecule-to-electrodes coupling.",
        "positive": "Oscillatory shear flows of dense suspensions at imposed pressure:\n  Rheology and micro-structure: Oscillatory shear has been widely used to study the rheological properties of\nsuspensions under unsteady shear. Furthermore, recent works have shown that\noscillatory flows can improve the flowability of dense suspensions. While most\nstudies have been done under constant volume we here study oscillatory shear\nflows of a two-dimensional suspensions using a normal pressure-controlled\nset-up. To characterise the rheology, we introduce both a complex macroscopic\nfriction coefficient $\\mu^{*}$, following the convention of the complex\nviscosity $\\eta^{*}$, and a shear-rate averaged viscous number $J'$. The\nrheology and microstructure of dense suspensions are studied by systematically\nvarying both the strain magnitude $\\gamma_0$ and $J'$ using numerical\nsimulations. We study both suspensions composed of frictional ($\\mu_p=0.4$) or\nfrictionless ($\\mu_p=0$) particles and find that the critical values, as $J'\n\\to 0$, of both the complex macroscopic friction and the number of contacts,\nboth total and sliding, decrease with decreasing $\\gamma_0$. For suspensions\ncomposed of frictional particles we also find that the critical (i.e.~the shear\njamming) packing fraction $\\phi_c$ increase with decreasing $\\gamma_0$. In both\ncases, frictional and frictionless, we find that the rheological response\napproaching the shear jamming turns from a viscous to an elastic response as\n$\\gamma_0$ is lowered below $\\sim0.33$."
    },
    {
        "anchor": "Bogoliubov approach to superfluidity of atoms in an optical lattice: We use the Bogoliubov theory of atoms in an optical lattice to study the\napproach to the Mott-insulator transition. We derive an explicit expression for\nthe superfluid density based on the rigidity of the system under phase\nvariations. This enables us to explore the connection between the quantum\ndepletion of the condensate and the quasi-momentum distribution on the one hand\nand the superfluid fraction on the other. The approach to the insulator phase\nmay be characterized through the filling of the band by quantum depletion,\nwhich should be directly observable via the matter wave interference patterns.\nWe complement these findings by self-consistent Hartree-Fock-Bogoliubov-Popov\ncalculations for one-dimensional lattices including the effects of a parabolic\ntrapping potential.",
        "positive": "Electrophoresis of Janus Particles: a Molecular Dynamics simulation\n  study: In this work, we use Molecular Dynamics and Lattice-Boltzmann simulations to\nstudy the properties of charged Janus particles in an electric field. We show\nthat for relatively small net charge and thick electrostatic diffuse layer\nmobilities of Janus particles and uniformly charged colloids of the same net\ncharge are identical. However, for higher charges and thinner diffuse layers\nJanus particles always show lower electrophoretic mobility. We also demonstrate\nthat Janus particles align with the electric field and the angular deviation\nfrom the field's direction are related to their dipole moment. We show that the\nlatter is affected by the thickness of the electrostatic diffuse layer and\nstrongly correlates with the electrophoretic mobility."
    },
    {
        "anchor": "When the Hotter Cools More Quickly: Mpemba Effect in Granular Fluids: Under certain conditions, two samples of fluid at different initial\ntemperatures present a counterintuitive behavior known as the Mpemba effect: it\nis the hotter system that cools sooner. Here, we show that the Mpemba effect is\npresent in granular fluids, both in uniformly heated and in freely cooling\nsystems. In both cases, the system remains homogeneous, and no phase transition\nis present. Analytical quantitative predictions are given for how differently\nthe system must be initially prepared to observe the Mpemba effect, the\ntheoretical predictions being confirmed by both molecular dynamics and Monte\nCarlo simulations. Possible implications of our analysis for other systems are\nalso discussed.",
        "positive": "The Boson Peak and Disorder in Hard Sphere Colloidal Systems: The Boson peak is believed to be the key to the fundamental understanding of\nthe anomalous thermodynamic properties of glasses, notably the anomalous peak\nin the heat capacity at low temperatures; it is believed to be due to an excess\nof low frequency vibrational modes and a manifestation of the structural\ndisorder in these systems. We study the thermodynamics and vibrational dynamics\nof colloidal glasses and (defected) crystals. The experimental determination of\nthe vibrational density of states allows us to directly observe the Boson peak\nas a strong enhancement of low frequency modes. Using a novel method [Zargar et\nal., Phys. Rev. Lett. 110, 258301 (2013)] to determine the free energy, we also\ndetermine the entropy and the specific heat experimentally. It follows that the\nemergence of the Boson peak and high values of the specific heat are directly\nrelated and are specific to the glass: for a very defected crystal with a\ndisorder that is only slightly smaller than for the glass, both the\nlow-frequency density of states and the specific heat are significantly smaller\nthan in the glass."
    },
    {
        "anchor": "Symmetry Induced 4-Wave Capillary Wave Turbulence: We report theoretical and experimental results on 4-wave capillary wave\nturbulence. A system consisting of two inmiscible and incompressible fluids of\nthe same density can be written in a Hamiltonian way for the conjugated pair\n$(\\eta,\\Psi)$. When given the symmetry $z\\to-z$, the set of weakly non-linear\ninteracting waves display a Kolmogorov-Zakharov (KZ) spectrum $n_k\\sim k^{-4}$\nin wave vector space. The wave system was studied experimentally with two\ninmiscible fluids of almost equal densities (water and silicon oil) where the\ncapillary surface waves are excited by a low frequency random forcing. The\npower spectral density (PSD) and probability density function (PDF) of the\nlocal wave amplitude are studied. Both theoretical and experimental results are\nin fairly good agreement with each other.",
        "positive": "Finite Element Simulation of Dense Wire Packings: A finite element program is presented to simulate the process of packing and\ncoiling elastic wires in two- and three-dimensional confining cavities. The\nwire is represented by third order beam elements and embedded into a\ncorotational formulation to capture the geometric nonlinearity resulting from\nlarge rotations and deformations. The hyperbolic equations of motion are\nintegrated in time using two different integration methods from the Newmark\nfamily: an implicit iterative Newton-Raphson line search solver, and an\nexplicit predictor-corrector scheme, both with adaptive time stepping. These\ntwo approaches reveal fundamentally different suitability for the problem of\nstrongly self-interacting bodies found in densely packed cavities. Generalizing\nthe spherical confinement symmetry investigated in recent studies, the packing\nof a wire in hard ellipsoidal cavities is simulated in the frictionless elastic\nlimit. Evidence is given that packings in oblate spheroids and scalene\nellipsoids are energetically preferred to spheres."
    },
    {
        "anchor": "Dynamic facilitation observed near the colloidal glass transition: We present experimental confirmation of dynamic facilitation in monodisperse\nand bidisperse colloidal suspensions near the glass transition volume fraction.\nCorrelations in particle dynamics are seen to exist not only in space (clusters\nand strings) but also as bubbles in space-time. Quantitatively, highly mobile\nparticles are more likely (than immobile particles) to have nearest neighbors\nthat were highly mobile in immediately preceding times. The interpretation is\nthat a particle's mobility enables or facilitates the subsequent motion of its\nneighbors. Facilitation is most pronounced at the relaxation time that\ncorresponds with cage-breaking, when dynamic heterogeneity is also maximized.",
        "positive": "Dynamics and Melting of Stripes, Crystals, and Bubbles with Quenched\n  Disorder: Two-dimensional systems in which there is a competition between long-range\nrepulsion and short range attraction exhibit a remarkable variety of patterns\nsuch as stripes, bubbles, and labyrinths. Such systems include magnetic films,\nLangmuir monolayers, polymers, gels, water-oil mixtures, and two-dimensional\nelectron systems. In many of these systems quenched disorder from the\nunderlying substrate may be present. We examine the dynamics and stripe\nformation in the presence of both an applied dc drive and quenched disorder.\nWhen the disorder strength exceeds a critical value, an applied dc drive can\ninduce a dynamical stripe ordering transition to a state that is more ordered\nthan the originating undriven, unpinned pattern."
    },
    {
        "anchor": "Relaxation of a Moving Contact Line and Landau-Levich Effect: The dynamics of the deformations of a moving contact line is formulated. It\nis shown that an advancing contact line relaxes more quickly as compared to the\nequilibium case, while for a receding contact line there is a corresponding\nslowing down. For a receding contact line on a heterogeneous solid surface, it\nis found that a roughening transition takes place which formally corresponds to\nthe onset of leaving a Landau-Levich film.",
        "positive": "Canonical Statistics of Trapped Ideal and Interacting Bose Gases: The mean ground state occupation number and condensate fluctuations of\ninteracting and non-interacting Bose gases confined in a harmonic trap are\nconsidered by using a canonical ensemble approach. To obtain the mean ground\nstate occupation number and the condensate fluctuations, an analytical\ndescription for the probability distribution function of the condensate is\nprovided directly starting from the analysis of the partition function of the\nsystem. For the ideal Bose gas, the probability distribution function is found\nto be a Gaussian one for the case of the harmonic trap. For the interacting\nBose gas, using a unified approach the condensate fluctuations are calculated\nbased on the lowest-order perturbation method and on Bogoliubov theory. It is\nfound that the condensate fluctuations based on the lowest-order perturbation\ntheory follow the law $<delta^{2}N_{\\bf 0}>\\sim N$, while the fluctuations\nbased on Bogoliubov theory behave as $N^{4/3}$."
    },
    {
        "anchor": "On Magnetoacoustic Waves in Finitely Deformed Elastic Solids: In this paper, in the context of the quasi-magnetostatic approximation, we\nexamine incremental motions superimposed on a static finite deformation of a\nmagnetoelastic material in the presence of an applied magnetic field. Explicit\nexpressions are obtained for the associated magnetoacoustic (or magnetoelastic\nmoduli) tensors in the case of an incompressible isotropic magnetoelastic\nmaterial, and these are then used to study the propagation of incremental plane\nwaves. The propagation condition is derived in terms of a generalized acoustic\ntensor and the results are illustrated by obtaining explicit formulas in two\nspecial cases: first, when the material is undeformed but subject to a uniform\nbias field and second for a prototype model of magnetoelastic interactions in\nthe finite deformation regime. The results provide a basis for the experimental\ndetermination of the material parameters of a magneto-sensitive elastomer from\nmeasurements of the speed of incremental waves for different pre-strains, bias\nmagnetic fields, and directions of propagation.",
        "positive": "Modeling of Multicomponent Three-Dimensional Vesicles: In many interfacial flow systems, variations of surface properties lead to\nnovel and interesting behaviors. In this work a three-dimensional model of flow\ndynamics for multicomponent vesicles is presented. The surface composition is\nmodeled using a two-phase surface Cahn-Hilliard system, while the interface is\ncaptured using a level set jet scheme. The interface is coupled to the\nsurrounding fluid via a variation of energy approach. Sample energies\nconsidered include the total bending, variable surface tension energy, and\nphase segregation energy. The fully coupled system for surface inhomogeneities,\nand thus varying interface material properties is presented, as are the\nassociated numerical methods. Numerical convergence and sample results\ndemonstrate the validity of the model."
    },
    {
        "anchor": "Dynamical Effective Field Model for Interacting Ferrofluids: II. The\n  proper relaxation time and effects of dynamic correlations: The recently proposed dynamical effective field model (DEFM) is\nquantitatively accurate for describing dynamical magnetic response of\nferrofluids. In paper I it is derived under the framework of dynamical density\nfunctional theory, via which the original ensemble of bare Brownian particles\nis mapped to an ensemble of dressed particles. However, it remains to clarify\nhow the characteristic rotational relaxation time of a dressed particle,\ndenoted by $\\tau_r$, is quantitatively related to that of a bare particle,\ndenoted by $\\tau^0_r$. By building macro-micro connections via two different\nroutes, I reveal that under some gentle assumptions $\\tau_r$ can be identified\nwith the long-time rotational self-diffusion time. I further introduce two\nsimple but useful integrated correlation factors, describing the effects of\nquasi-static (adiabatic) and dynamic (nonadiabatic) inter-particle\ncorrelations, respectively. In terms of both correlation factors I reformulate\nthe dynamic magnetic susceptibility in an illuminating and elegant form.\nRemarkably, it shows that the macro-micro connection is established via two\nsuccessive steps: a dynamical coarse-graining with nonadiabatic effects\naccounted for by the dynamic factor, followed by equilibrium statistical\nmechanical averaging captured by the static factor. Surprisingly,\n$\\tau_r/\\tau^0_r$ is found insensitive to changes of particle volume fraction.\nI provide a physical picture to explain it. Furthermore, an empirical formula\nis proposed to characterize the dependence of $\\tau_r/\\tau^0_r$ on\ndipole-dipole interaction strength. The DEFM supplemented with this formula\nleads to parameter-free predictions in good agreement with results from\nBrownian dynamics simulations. The theoretical developments presented in this\npaper may have important consequences to studies of ferrofluid dynamics in\nparticular and other systems modelled by DDFTs in general.",
        "positive": "Prediction of Electronic Properties of Radical-Containing Polymers at\n  Coarse-Grained Resolutions: The properties of soft electronic materials depend on the coupling of\nelectronic and conformational degrees of freedom over a wide range of\nspatiotemporal scales. Description of such properties requires multiscale\napproaches capable of, at the same time, accessing electronic properties and\nsampling the conformational space of soft materials. This could in principle be\nrealized by connecting the coarse-grained (CG) methodologies required for\nadequate conformational sampling to conformationally-averaged electronic\nproperty distributions via backmapping to atomistic-resolution level models and\nrepeated quantum-chemical calculations. Computational demands of such\napproaches, however, have hindered their application in high-throughput\ncomputer-aided soft materials discovery. Here, we present a method that,\ncombining machine learning and CG techniques, can replace traditional\nbackmapping-based approaches without sacrificing accuracy. We illustrate the\nmethod for an emerging class of soft electronic materials, namely\nnon-conjugated, radical-containing polymers, promising materials for\nall-organic energy storage. Supervised machine learning models are trained to\nlearn the dependence of electronic properties on polymer conformation at CG\nresolutions. We then parametrize CG models that retain electronic structure\ninformation, simulate CG condensed phases, and predict the electronic\nproperties of such phases solely from the CG degrees of freedom. We validate\nour method by comparing it against a full backmapping-based approach, and find\ngood agreement between both methods. This work demonstrates the potential of\nthe proposed method to accelerate multiscale workflows, and provides a\nframework for the development of CG models that retain electronic structure\ninformation."
    },
    {
        "anchor": "Simultaneous and independent topological control of identical\n  microparticles in non-periodic energy landscapes: Topological protection ensures stability of information and particle\ntransport against perturbations. We explore experimentally and computationally\nthe topologically protected transport of magnetic colloids above spatially\ninhomogeneous magnetic patterns, revealing that transport complexity can be\nencoded in both the driving loop and the pattern. Complex patterns support\nintricate transport modes when the microparticles are subjected to simple\ntime-periodic loops of a uniform magnetic field. We design a pattern featuring\na topological defect that functions as an attractor or a repeller of\nmicroparticles, as well as a pattern that directs microparticles along a\nprescribed complex trajectory. Using simple patterns and complex loops, we\nsimultaneously and independently control the motion of several identical\nmicroparticles differing only in their positions above the pattern. Combining\ncomplex patterns and complex loops we transport microparticles from unknown\nlocations to predefined positions and then force them to follow arbitrarily\ncomplex trajectories concurrently. Our findings pave the way for new avenues in\ntransport control and dynamic self-assembly in colloidal science.",
        "positive": "The interactions between comminution, segregation and remixing in\n  granular flows: Granular segregation is an important mechanism for industrial processes\naiming at mixing grains. Additionally, it plays a pivotal role in determining\nthe kinematics of geophysical flows. Because of segregation, the grainsize\ndistribution varies in space and time. Additional complications arise from the\npresence of comminution, where new particles are created, enhancing\nsegregation. This has a feedback on the comminution process, as particles\nchange their local neighbourhood. Simultaneously, particles are generally\nundergoing remixing, further complicating the segregation and comminution\nprocesses. The interaction between these mechanisms is explored using a\ncellular automaton with three rules: one for each of segregation, comminution\nand mixing. The interplay between these rules creates complex patterns, as seen\nin segregating systems, and depth dependent grading curves, which have been\nobserved in avalanche runout. At every depth, log-normal grading curves are\nproduced at steady state, as measured experimentally in avalanche and debris\nflow deposits."
    },
    {
        "anchor": "Structural Properties of the Sliding Columnar Phase in Layered Liquid\n  Crystalline Systems: Under appropriate conditions, mixtures of cationic and neutral lipids and DNA\nin water condense into complexes in which DNA strands form local 2D smectic\nlattices intercalated between lipid bilayer membranes in a lamellar stack.\nThese lamellar DNA-cationic-lipid complexes can in principle exhibit a variety\nof equilibrium phases, including a columnar phase in which parallel DNA strands\nfrom a 2D lattice, a nematic lamellar phase in which DNA strands align along a\ncommon direction but exhibit no long-range positional order, and a possible new\nintermediate phase, the sliding columnar (SC) phase, characterized by a\nvanishing shear modulus for relative displacement of DNA lattices but a\nnonvanishing modulus for compressing these lattices. We develop a model capable\nof describing all phases and transitions among them and use it to calculate\nstructural properties of the sliding columnar phase. We calculate displacement\nand density correlation functions and x-ray scattering intensities in this\nphase and show, in particular, that density correlations within a layer have an\nunusual $\\exp(- {\\rm const.} \\ln^2 r)$ dependence on separation r. We\ninvestigate the stability of the SC phase with respect to shear couplings\nleading to the columnar phase and dislocation unbinding leading to the lamellar\nnematic phase. For models with interactions only between nearest neighbor\nplanes, we conclude that the SC phase is not thermodynamically stable.\nCorrelation functions in the nematic lamellar phase, however, exhibit SC\nbehavior over a range of length scales",
        "positive": "Effect of stretching-induced changes in hydrodynamic screening on\n  coil-stretch hysteresis of unentangled polymer solutions: Extensional rheometry and Brownian Dynamics simulations of flexible polymer\nsolutions confirm predictions based on blob concepts that coil--stretch\nhysteresis in extensional flows increases with concentration, reaching a\nmaximum at the critical overlap concentration $c^\\ast$ before progressively\nvanishing in the semidilute regime. These observations demonstrate that chain\nstretching strengthens intermolecular hydrodynamic screening in dilute\nsolutions, but weakens it in semidilute solutions. Flow can thus strongly\nmodify the concentration dependence of viscoelastic properties of polymer\nsolutions."
    },
    {
        "anchor": "Density functional theory for dense nematics with steric interactions: The celebrated work of Onsager on hard particle systems, based on the\ntruncated second order virial expansion, is valid at relatively low volume\nfractions for large aspect ratio particles. While it predicts the\nisotropic-nematic phase transition, it fails to provide a realistic equation of\nstate in that the pressure remains finite for arbitrarily high densities. In\nthis work, we derive a mean field density functional form of the Helmholtz free\nenergy for nematics with hard core repulsion. In addition to predicting the\nisotropic-nematic transition, the model provides a more realistic equation of\nstate. The energy landscape is much richer, and the orientational probability\ndistribution function in the nematic phase possesses a unique feature: it\nvanishes on a nonzero measure set in orientational space.",
        "positive": "Oscillations of small bubbles and medium yielding in elastoviscoplastic\n  fluids: We investigate the radial oscillations of small gas bubbles trapped in\nyield-stress fluid and driven by an acoustic pressure field. We model the\nrheological behavior of the yield-stress fluid using the recently developed\nelasto-visco-plastic (EVP) constitutive equation that takes into account the\nelastic and visco-plastic deformations of the material [P. Saramito, J.\nNonNewton. Fluid Mech. 158 (1-3) (2009) pp.154-161]. Assuming that the bubble\nremains spherical during the pressure driving, we reduce the problem to a set\nof ODEs and an integrodifferential equation, which we solve numerically for the\ncase of two yield-stress fluids, a sot Carbopol gel and a stiffer Kaolin\nsuspension. We find that, depending on the amplitude and frequency of the\npressure field, the radial oscillations of the bubble produce elastic stresses\nthat may or may not suffice to yield the surrounding material. We evaluate the\ncritical amplitude of the acoustic pressure required to achieve yielding and we\nfind a good agreement between numerical simulations and an analytical formula\nderived under the assumption of linear deformations. Finally, we examine the\nbubble oscillation amplitude for a very wide range of applied pressures both\nbelow and above the critical value to assess the impact of yielding on the\nbubble dynamics. This analysis could be used to identify a signature of\nyielding in experiments where the radial dynamics of a bubble is measured. More\ngenerally, these results can be used to rationalize the optimal conditions for\npressure-induced bubble release from yield-stress fluids, which is relevant to\nvarious biomedical and industrial applications, including oil industry and food\nprocessing."
    },
    {
        "anchor": "Sustainable and effective antimicrobial surface based on cellulose thin\n  films: In the present work, we developed a sustainable and effective antimicrobial\nsurface film based on Micro-Fibrillated Cellulose. The resulting porous\ncellulose thin film is barely noticeable to human eyes due to its sub-micron\nthickness, of which the coverage, porosity and microstructure can be modulated\nby the formulations developed. Using goniometers and a quartz crystal\nmicrobalance (QCM), we observed a threefold reduction in water contact angles\nand accelerated (more than 50% faster) water evaporation kinetics on the\ncellulose film. The thin film exhibits not only a rapid inactivation effect\nagainst SARS-CoV-2 in 5 minutes, following deposition of the virus loaded\ndroplets, but also an exceptional ability to reduce contact transfer of liquid,\ne.g. respiratory droplets, onto surfaces such as artificial skin by more than\n90%. It also exhibits excellent antimicrobial performance in inhibiting the\ngrowth of both gram-negative and gram-positive bacteria (E.coli and\nS.epidermidis) due to the excellent porosity and hydrophilicity. Additionally,\nthe cellulose film shows nearly 100% resistance to skin scraping in dry\ncondition thanks to its strong attachment to the substrate, whilst good\nremovability once wetted, suggesting its practical suitability for daily use.\nImportantly, the coating can be formed on solid substrates readily by spraying\nand requires solely a simple formulation of a plant-based cellulose material\nwith no additives, rendering it a scalable, affordable and green solution for\nantimicrobial surfaces. Implementing such cellulose films could thus play a\nsignificant role in controlling future pan- and epidemics, in particularly\nduring the first phase when appropriate medication needs to be developed.",
        "positive": "Activity pulses induce spontaneous flow reversals in viscoelastic\n  environments: Complex interactions between cellular systems and their surrounding\nextracellular matrices are emerging as important mechanical regulators of cell\nfunctions such as proliferation, motility, and cell death, and such cellular\nsystems are often characterized by pulsating acto-myosin activities. Here,\nusing an active gel model, we numerically explore the spontaneous flow\ngeneration by activity pulses in the presence of a viscoelastic medium. The\nresults show that cross-talk between the activity-induced deformations of the\nviscoelastic surroundings with the time-dependent response of the active medium\nto these deformations can lead to the reversal of spontaneously generated\nactive flows. We explain the mechanism behind this phenomenon based on the\ninteraction between the active flow and the viscoelastic medium. We show the\nimportance of relaxation timescales of both the polymers and the active\nparticles and provide a phase-space over which such spontaneous flow reversals\ncan be observed. Our results suggest new experiments investigating the role of\ncontrolled pulses of activity in living systems ensnared in complex\nmircoenvironments."
    },
    {
        "anchor": "Rigidity percolation by next-nearest-neighbor braces on generic and\n  regular isostatic lattices: We study rigidity percolation transitions in two-dimensional central-force\nisostatic lattices, including the square and the kagome lattices, as\nnext-nearest-neighbor bonds (\"braces\") are randomly added to the system. In\nparticular, we focus on the differences between regular lattices, which are\nperfectly periodic, and generic lattices with the same topology of bonds but\nwhose sites are at random positions in space. We find that the regular square\nand kagome lattices exhibit a rigidity percolation transition when the number\nof braces is $\\sim L\\ln L$, where $L$ is the linear size of the lattice. This\ntransition exhibits features of both first order and second order transitions:\nthe whole lattice becomes rigid at the transition, whereas there exists a\ndiverging length scale. In contrast, we find that the rigidity percolation\ntransition in the generic lattices occur when the number of braces is very\nclose to the number obtained from the Maxwell's law for floppy modes, which is\n$\\sim L$. The transition in generic lattices is a very sharp first-order-like\ntransition, at which the addition of one brace connects all small rigid regions\nin the bulk of the lattice, leaving only floppy modes on the edge. We\ncharacterize these transitions using numerical simulations and develop analytic\ntheories capturing each transition. Our results relate to other interesting\nproblems including jamming and bootstrap percolation.",
        "positive": "Solvent Entropy in and Coarse-Graining of Polymer Lattice Models: The self- and mutual-avoiding walk used in conventional lattice models for\npolymeric systems requires that all lattice sites, polymer segments, and\nsolvent molecules (unoccupied lattice sites) have the same volume. This\nincorrectly accounts for the solvent entropy (i.e., size ratio between polymer\nsegments and solvent molecules), and also limits the coarse-graining capability\nof such models, where the invariant degree of polymerization controlling the\nsystem fluctuations is too small (thus exaggerating the system fluctuations)\ncompared to that in most experiments. Here we show how to properly account for\nthe solvent entropy in the recently proposed lattice models with multiple\noccupancy of lattice sites [Q. Wang, Soft Matter 5, 4564 (2009)], and present a\nquantitative coarse-graining strategy that ensures both the solvent entropy and\nthe fluctuations in the original systems are properly accounted for using such\nlattice models. Although proposed based on homogeneous polymer solutions, our\nstrategy is equally applicable to inhomogeneous systems such as polymer brushes\nimmersed in a small-molecule solvent."
    },
    {
        "anchor": "A Structurally Self-Assembled Peptide Nano-Architecture by One-Step\n  Electrospinning: Self-assembling peptides (SAPs) have shown to offer great promise in\ntherapeutics and have the ability to undergo self-assembly and form ordered\nnanostructures. However SAP gels are often associated with inherent weak and\ntransient mechanical properties and incorporation of them into polymeric\nmatrices is a route to enhance their mechanical stability. The aim of this work\nwas to incorporate P11-8 peptide (CH3COQQRFOWOFEQQNH2) within\npoly(epsilon-caprolactone) (PCL) fibrous webs via one-step electrospinning,\naiming to establish the underlying relationships between spinning process,\nmolecular peptide conformation, and material internal architecture.\nElectrospinning of PCL solutions (6% w/w) in hexafluoro-2-propanol (HFIP)\ncontaining up to 40 mg/ml P11-8 resulted in the formation of fibres in both\nnano- (10-100 nm) and submicron range (100-700 nm), in contrast to PCL only\nwebs, which displayed a predominantly submicron fibre distribution. FTIR and CD\nspectroscopy on both PCL/peptide solutions and resulting electrospun webs\nrevealed monomeric and beta-sheet secondary conformation, respectively,\nsuggesting the occurrence of peptide self-assembly during electrospinning due\nto solvent evaporation. The peptide concentration (0 -> 40 mg/ml) was found to\nprimarily affect the internal structure of the fabric at the nano-scale, whilst\nwater as well as cell culture medium contact angles were dramatically\ndecreased. Nearly no cytotoxic response (> 90% cell viability) was observed\nwhen L929 mouse fibroblasts were cultured in contact with electrospun peptide\nloaded samples. This novel nanofibrous architecture may be the basis for an\ninteresting material platform for e.g. hard tissue repair, in light of the\npresence of the self assembled P11-8 in the PCL fibrous structure.",
        "positive": "Flapping motion and force generation in a viscoelastic fluid: In a variety of biological situations, swimming cells have to move through\ncomplex fluids. Similarly, mucociliary clearance involves the transport of\npolymeric fluids by beating cilia. Here, we consider the extent to which\ncomplex fluids could be exploited for force generation on small scales. We\nconsider a prototypical reciprocal motion (i.e. identical under time-reversal\nsymmetry): The periodic flapping of a tethered semi-infinite plane. In the\nNewtonian limit, such motion cannot be used for force generation according to\nPurcell's scallop theorem. In a polymeric fluid (Oldroyd-B, and its\ngeneralization), we show that this is not the case and calculate explicitly the\nforces on the flapper for small-amplitude sinusoidal motion. Three setups are\nconsidered: a flapper near a wall, a flapper in a wedge, and a two-dimensional\nscallop-like flapper. In all cases, we show that at quadratic order in the\noscillation amplitude, the tethered flapping motion induces net forces but no\naverage flow. Our results demonstrate therefore that the scallop theorem is not\nvalid in polymeric fluids. The reciprocal component of the movement of\nbiological appendages such as cilia can thus generate nontrivial forces in\npolymeric fluid such as mucus, and normal-stress differences can be exploited\nas a pure viscoelastic force generation and propulsion method."
    },
    {
        "anchor": "Parity-time symmetry breaking enables swarming motility in\n  Caenorhabditis elegans: Nonreciprocal interactions break action-reaction symmetry in systems of\ninteracting bodies. This process inevitably introduces non-Hermitian dynamics\nwhich with its hallmark signature called exceptional points (EPs) has been a\nsubject of intense research across different disciplines ranging from photonics\nto metamaterials. Whether non-Hermiticity and EPs are a fundamental property of\nnature and if so, how nature utilizes them to gain competitive advantage have\nremained largely unanswered. Although biological systems feature many examples\nof non-reciprocal interactions with the potential to drive non-Hermitian\ndynamics, these are often theoretically overlooked and not experimentally\ninvestigated. Here, we demonstrate in an active matter composed of social\nanimal Caenorhabditis elegans and bacteria, non-Hermitian dynamics, and the\nemergence of EPs owing to the nonreciprocal nature of oxygen sensing,\nnonequilibrium interfacial current, and bacterial consumption. We observed that\nwhen driven through the EP, the system collectively breaks parity-time (PT)\nsymmetry leading to traveling waves and arrested phase separation. We further\nfind that these features enable the collective ability to localize interfaces\nbetween broken and exact PT-phases. Remarkably, this ability provides a strong\nevolutionary advantage to animals living in soil. Altogether our results\nprovide mechanistic insights into the detailed symmetries controlling the\ncollective response of biological systems; answer a long-standing problem; and\ngive an example of the EP-enabled dynamics in a biological system.",
        "positive": "From square-well to Janus: Improved algorithm for integral equation\n  theory and comparison with thermodynamic perturbation theory within the\n  Kern-Frenkel model: Building upon past work on the phase diagram of Janus fluids [Sciortino et\nal., Phys. Rev. Lett. \\textbf{103}, 237801 (2009)], we perform a detailed study\nof integral equation theory of the Kern-Frenkel potential with coverage that is\ntuned from the isotropic square-well fluid to the Janus limit. An improved\nalgorithm for the reference hypernetted-chain (RHNC) equation for this problem\nis implemented that significantly extends the range of applicability of RHNC.\nResults for both structure and thermodynamics are presented and compared with\nnumerical simulations. Unlike previous attempts, this algorithm is shown to be\nstable down to the Janus limit, thus paving the way for analyzing the\nfrustration mechanism characteristic of the gas-liquid transition in the Janus\nsystem. The results are also compared with Barker-Henderson thermodynamic\nperturbation theory on the same model. We then discuss the pros and cons of\nboth approaches within a unified treatment. On balance, RHNC integral equation\ntheory, even with an isotropic hard-sphere reference system, is found to be a\ngood compromise between accuracy of the results, computational effort, and\nuniform quality to tackle self-assembly processes in patchy colloids of complex\nnature. Further improvement in RHNC however clearly requires an\n\\emph{anisotropic} reference bridge function."
    },
    {
        "anchor": "Solute Induced Jittery Motion of Self-Propelled Droplets: The intriguing role of the presence of solutes in the activity of a\nself-propelling droplet is investigated. A system of self-propelling micron\nsized 4-pentyl-4-biphenylcarbonitrile (5CB) droplets in an aqueous solution of\ntetradecyltrimethylammonium bromide (TTAB) as surfactant is considered. It is\nshown that addition of glycerol causes the active 5CB droplet to exhibit a\ntransition from smooth to jittery motion. The motion is found to be independent\nof the droplet size and the nematic state of 5CB. Analogous experiments with\nPolyacrylamide (PAAm), Polyvinylpyrrolidone (PVP) and Polyvinyl Alcohol (PVA),\nas solutes confirm that such a transition cannot merely be explained solely\nbased on the viscosity or Peclet number of the system. We propose that the\nspecific nature of physicochemical interactions between the solute and the\ndroplet interface is at the root of this transition. The experiments show that\nthe time-scales associated with the influx and redistribution of surfactants at\nthe interface are altered in the presence of solutes. Glycerol and PVP\nsignificantly enhance the rate of solubilization of the 5CB droplets resulting\nin a quicker re-distribution of the adsorbed TTAB molecules on the interface,\ncausing the droplet to momentarily stop and then restart in an independent\ndirection. On the other hand, low solubilization rates in the presence of PAAm\nand PVA lead to smooth trajectories. Our hypothesis is supported by the time\nevolution of droplet size and interfacial velocity measurements in the presence\nand absence of solute. Overall, our results provide fundamental insights into\nthe complex interactions emerging due to the presence of solutes.",
        "positive": "Critical behavior in colloid-polymer mixtures: theory and simulation: We extensively investigated the critical behavior of mixtures of colloids and\npolymers via the two-component Asakura-Oosawa model and its reduction to a\none-component colloidal fluid using accurate theoretical and simulation\ntechniques. In particular the theoretical approach, hierarchical reference\ntheory [Adv. Phys. 44, 211 (1995)], incorporates realistically the effects of\nlong-range fluctuations on phase separation giving exponents which differ\nstrongly from their mean-field values, and are in good agreement with those of\nthe three-dimensional Ising model. Computer simulations combined with\nfinite-size scaling analysis confirm the Ising universality and the accuracy of\nthe theory, although some discrepancy in the location of the critical point\nbetween one-component and full-mixture description remains. To assess the limit\nof the pair-interaction description, we compare one-component and two-component\nresults."
    },
    {
        "anchor": "Diffusion dynamics of supercooled water modeled with the cage-jump\n  motion and hydrogen-bond rearrangement: The slow dynamics of glass-forming liquids is generally ascribed to the\ncage-jump motion. In the cage-jump picture, a molecule remains in a cage formed\nby neighboring molecules, and after a sufficiently long time, it jumps to\nescape from the original position by cage-breaking. The clarification of the\ncage-jump motion is therefore linked to unraveling the fundamental element of\nthe slow dynamics. Here, we develop a cage-jump model for the dynamics of\nsupercooled water. The caged and jumping states of a water molecule are\nintroduced with respect to the hydrogen-bond (H-bond) rearrangement process,\nand describe the motion in supercooled states. It is then demonstrated from the\nmolecular dynamics simulation of the TIP4P/2005 model that the characteristic\nlength and time scales of cage-jump motions provide a good description of the\nself-diffusion constant that is determined in turn from the long-time behavior\nof the mean square displacement. Our cage-jump model thus enables to connect\nbetween H-bond dynamics and molecular diffusivity.",
        "positive": "Finite-size effects in intracellular microrheology: We propose a model to explain finite-size effects in intracellular\nmicrorheology observed in experiments. The constrained dynamics of the\nparticles in the intracellular medium, treated as a viscoelastic medium, is\ndescribed by means of a diffusion equation in which interactions of the\nparticles with the cytoskeleton are modelled by a harmonic force. The model\nreproduces the observed power-law behavior of the mean-square displacement in\nwhich the exponent depends on the ratio between\nparticle-to-cytoskeleton-network sizes."
    },
    {
        "anchor": "Mechanical feedback controls the emergence of dynamical memory in\n  growing tissue monolayers: The growth of a tissue, which depends on cell-cell interactions and\nbiologically relevant process such as cell division and apoptosis, is regulated\nby a mechanical feedback mechanism. We account for these effects in a minimal\ntwo-dimensional model in order to investigate the consequences of mechanical\nfeedback, which is controlled by a critical pressure, $p_c$. A cell can only\ngrow and divide if the pressure it experiences, due to interaction with its\nneighbors, is less than $p_c$. Because temperature is an irrelevant variable in\nthe model, the cell dynamics is driven by self-generated active forces (SGAFs)\nthat are created by cell division. It is shown that even in the absence of\nintercellular interactions, cells undergo diffusive behavior. The SGAF driven\ndiffusion is indistinguishable from the well-known dynamics of a free Brownian\nparticle at a fixed finite temperature. When intercellular interactions are\ntaken into account, we find persistent temporal correlations in the force-force\nautocorrelation function ($FAF$) that extends over timescale of several cell\ndivision times. The time-dependence of the $FAF$ reveals memory effects, which\nincreases as pc increases. The observed non-Markovian effects emerge due to the\ninterplay of cell division and mechanical feedback, and is inherently a\nnon-equilibrium phenomenon.",
        "positive": "The effect of pressure pulsing on the mechanical dewatering of nanofiber\n  suspensions: Dewatering processes are invariably encountered in the chemical manufacturing\nand processing of various bioproducts. In this study, Computational Fluid\nMechanics (CFD) simulations and theory are utilized to model and optimize the\ndewatering of commercial nanofiber suspensions. The CFD simulations are based\non the volume-averaged Navier-Stokes equations while the analytical model is\ndeduced from the empirical Darcy's law for dewatering flows. The results are\nthen successfully compared to experimental data on commercial cellulose\nsuspensions obtained with a Dynamic Drainage Analyzer (DDA). Both the CFD\nsimulations and the analytical model capture the dewatering flow profiles of\nthe commercial suspensions in an experiment utilizing a constant pressure\nprofile. However, a temporally varying pressure profile offers a superior\ndewatering performance, as indicated by both the simulations and the analytical\nmodel. Finally, the analytical model also predicts an optimized number of\npressure pulses, minimizing the time required to completely dewater the\nsuspension."
    },
    {
        "anchor": "Nonequilibrium dynamics and fluctuation-dissipation relation in a\n  sheared fluid: The nonequilibrium dynamics of a binary Lennard-Jones mixture in a simple\nshear flow is investigated by means of molecular dynamics simulations. The\nrange of temperature investigated covers both the liquid, supercooled and\nglassy states, while the shear rate covers both the linear and nonlinear\nregimes of rheology. The results can be interpreted in the context of a\nnonequilibrium, schematic mode-coupling theory developed recently, which makes\nthe theory applicable to a wide range of soft glassy materials. The behavior of\nthe viscosity is first investigated. In the nonlinear regime, strong\nshear-thinning is obtained. Scaling properties of the intermediate scattering\nfunctions are studied. Standard `mode-coupling properties' of factorization and\ntime-superposition hold in this nonequilibrium situation. The\nfluctuation-dissipation relation is violated in the shear flow in a way very\nsimilar to that predicted theoretically, allowing for the definition of an\neffective temperature Teff for the slow modes of the fluid. Temperature and\nshear rate dependencies of Teff are studied using density fluctuations as an\nobservable. The observable dependence of Teff is also investigated. Many\ndifferent observables are found to lead to the same value of Teff, suggesting\nseveral experimental procedures to access Teff. It is proposed that tracer\nparticle of large mass may play the role of an `effective thermometer'. When\nthe Einstein frequency of the tracers becomes smaller than the inverse\nrelaxation time of the fluid, a nonequilibrium equipartition theorem holds.\nThis last result gives strong support to the thermodynamic interpretation of\nTeff and makes it experimentally accessible in a very direct way.",
        "positive": "Directional freezing of binary colloidal suspensions: A model for size\n  fractionation of graphene oxide: The performance of graphene oxide(GO)-based materials strongly depends on the\nlateral size and size distribution of GO nanosheets. Various methods are\nemployed to prepare GO nanosheets with a narrow size distribution. One of the\npromising method was proposed recently by directionally freezing of a GO\naqueous dispersion at a controlled growth rate of the freezing front. We\ndevelop a theoretic model of binary colloids suspension, incorporating both the\nmoving freezing boundary and the preferential adsorption of colloidal particles\nto the ice phase. We numerically solve the coupled diffusion equations and\npresent state diagrams of size fractionation. Selective trapping of colloids\naccording to their size can be achieved by a suitable choice of the\nexperimental parameters, such as the adsorption rates and the freezing speed."
    },
    {
        "anchor": "Polarisation of cells and soft objects driven by mechanical\n  interactions: Consequences for migration and chemotaxis: We study a generic model for the polarisation and motility of self-propelled\nsoft objects, biological cells or biomimetic systems, interacting with a\nviscous substrate. The active forces generated by the cell on the substrate are\nmodelled by means of oscillating force multipoles at the cell-substrate\ninterface. Symmetry breaking and cell polarisation for a range of cell sizes\nnaturally `emerge' from long range mechanical interactions between oscillating\nunits, mediated both by the intracellular medium and the substrate. However,\nthe harnessing of cell polarisation for motility requires substrate-mediated\ninteractions. Motility can be optimised by adapting the oscillation frequency\nto the relaxation time of the system or when the substrate and cell viscosities\nmatch. Cellular noise can destroy mechanical coordination between\nforce-generating elements within the cell, resulting in sudden changes of\npolarisation. The persistence of the cell's motion is found to depend on the\ncell size and the substrate viscosity. Within such a model, chemotactic\nguidance of cell motion is obtained by directionally modulating the persistence\nof motion, rather than by modulating the instantaneous cell velocity, in a way\nthat resembles the run and tumble chemotaxis of bacteria.",
        "positive": "On the electrical double layer contribution to the interfacial tension\n  of protein crystals: We study the electrical double layer at the interface between a protein\ncrystal and a salt solution or a dilute solution of protein, and estimate the\ndouble layer's contribution to the interfacial tension of this interface. This\ncontribution is negative and decreases in magnitude with increasing salt\nconcentration. We also consider briefly the interaction between a pair of\nprotein surfaces."
    },
    {
        "anchor": "Actin, a model semi-flexible polymer: Actin is a filamentary protein which has many remarkable properties making it\nan ideal system for the study of the dynamics and mechanics of semi-flexible\npolymer solutions and gels; actin has a persistence length of over 10 microns\nand can polymerize to lengths of several tens of microns, this permits the use\nof video microscopy and other optical methods in the study polymer dynamics.\nMany associated proteins exist which can be used to regulate length or\ncrosslink filaments. We discuss the dynamics and rheology of these solutions.",
        "positive": "Extending classical nucleation theory to confined systems: Classical nucleation theory has been recently reformulated based on\nfluctuating hydrodynamics [J.F. Lutsko and M.A. Dur\\'{a}n-Olivencia, J. Chem.\nPhys. 138, 244908 (2013)]. The present work extends this effort to the case of\nnucleation in confined systems such as small pores and vesicles. The finite\navailable mass imposes a maximal supercritical cluster size and prohibits\nnucleation altogether if the system is too small. We quantity the effect of\nsystem size on the nuceation rate. We also discuss the effect of relaxing the\ncapillary-model assumption of zero interfacial width resulting in significant\nchanges in the nucleation barrier and nucleation rate."
    },
    {
        "anchor": "The speed of interfacial waves polarized in a symmetry plane: The surface-impedance matrix method is used to study interfacial waves\npolarized in a plane of symmetry of anisotropic elastic materials. Although the\ncorresponding Stroh polynomial is a quartic, it turns out to be analytically\nsolvable in quite a simple manner. A specific application of the result\nconcerns the calculation of the speed of a Stoneley wave, polarized in the\ncommon symmetry plane of two rigidly bonded anisotropic solids. The\ncorresponding algorithm is robust, easy to implement, and gives directly the\nspeed (when the wave exists) for any orientation of the interface plane, normal\nto the common symmetry plane. Through the examples of the couples\n(Aluminum)-(Tungsten) and (Carbon/epoxy)-(Douglas pine), some general features\nof a Stoneley wave speed are verified: the wave does not always exist; it is\nfaster than the slowest Rayleigh wave associated with the separated\nhalf-spaces.",
        "positive": "Gravity driven instability in elastic solids: We demonstrate the instability of the free surface of a soft elastic solid\nfacing downwards. Experiments are carried out using a gel of constant density\n$\\rho$, shear modulus $\\mu$, put in a rigid cylindrical dish of depth $h$. When\nturned upside down, the free surface of the gel undergoes a normal outgoing\nacceleration $g$. It remains perfectly flat for $\\rho g h/\\mu<\\alpha^* $ with\n$\\alpha^*\\simeq 6$, whereas a steady pattern spontaneously appears in the\nopposite case. This phenomenon results from the interplay between the\ngravitational energy and the elastic energy of deformation, which reduces the\nRayleigh waves celerity and vanishes it at the threshold."
    },
    {
        "anchor": "Temperature dependence of electrokinetic flux in Si nanochannel: Significant temperature effects on the electrokinetic transport in a\nnanochannel with a slab geometry are demonstrated using a molecular dynamics\n(MD) model. A system consisting of Na+ and Cl- ions dissolved in water and\nconfined between fixed crystalline silicon walls with negatively charged inner\nsurfaces in an external electric field was investigated. Lennard-Jones (LJ)\nforce fields and Coulomb electrostatic interactions with Simple Point Charge\nExtended (SPC/E) model were used to represent the interactions between ions,\nwater molecules, and channel wall atoms. Dependence of the flow of water and\nions on the temperature was examined. The magnitude of the water flux and even\nits direction are shown to be significantly affected by temperature. In\nparticular, the previously reported flow reversal phenomenon does not occur at\nhigher temperature. Temperature dependence of the flux was attributed to the\ncharge redistribution and to the changes in viscosity of water.",
        "positive": "A Study of the Evaporative Deposition Process: Pipes and Truncated\n  Transport Dynamics: We consider contact line deposition and pattern formation of a pinned\nevaporating thin drop. We identify and focus on the transport dynamics\ntruncated by the maximal concentration, proposed by Dupont, as the single\ndeposition mechanism. The truncated process, formalized as \"pipe models\",\nadmits a characteristic moving shock front solution that has a robust\nfunctional form and depends only on local conditions. By applying the models,\nwe solve the deposition process and describe the deposit density profile in\ndifferent asymptotic regimes. In particular, near the contact line the density\nprofile follows a scaling law that is proportional to the square root of the\nconcentration ratio, and the maximal deposit density/thickness occurs at about\n2/3 of the total drying time for uniform evaporation and 1/2 for\ndiffusion-controlled evaporation. Away from the contact line, we for the first\ntime identify the power-law decay of the deposit profile with respect to the\nradial distance. In comparison, our work is consistent with and extends\nprevious results. We also predict features of the depinning process and\nmultiple-ring patterns within Dupont model, and our predictions are consistent\nwith empirical evidence."
    },
    {
        "anchor": "Self-assembly of a binary mixture of iron oxide nanoparticles in\n  Langmuir film: X-ray scattering study: In present study we exploited Langmuir technique to produce self-assembled\narrays composed of monodisperse iron oxide nanoparticles 10 nm and 20 nm in\ndiameter and of their binary mixture. A combination of in-situ X-ray\nreflectometry and Grazing-incident small-Angle X-ray scattering was used to\nobtain in-plane and out-of-plane structure of the arrays directly on the water\nsurface. Surface pressure isotherms and X-ray reflectometry analysis showed\nthat monodisperse 10 nm nanoparticles form a highly ordered monolayer, while 20\nnm particles pack in three-dimensional clusters with a short-range\n(nearest-neighbor) correlations between the particles. In a binary mixture of\n10 nm and 20 nm nanoparticles composed in proportion 3:1 the self-assembly\nprocess results in a structure where the monolayer of 10 nm particles is\nperturbed by the larger particles. Non-trivial mixing causes an enlargement of\ninterparticle distance but keeps the symmetry of two-dimensional lattice of\nsmaller nanoparticles. Estimation of the acting interactions and micromagnetic\nsimulation suggest the optimal formation for monodisperse and binary ensembles.",
        "positive": "Fragile-to-strong transition in liquid silica: We investigate anomalies in liquid silica with molecular dynamics simulations\nand present evidence for a fragile-to-strong transition at around 3100 K-3300\nK. To this purpose, we studied the structure and dynamical properties of silica\nover a wide temperature range, finding four indicators of a fragile-to-strong\ntransition. First, there is a density minimum at around 3000 K and a density\nmaximum at 4700 K. The turning point is at 3400 K. Second, the local structure\ncharacterized by the tetrahedral order parameter changes dramatically around\n3000 K from a higher-ordered, lower-density phase to a less ordered,\nhigher-density phase. Third, the correlation time {\\tau} changes from an\nArrhenius behavior below 3300 K to a Vogel-Fulcher-Tammann behavior at higher\ntemperatures. Fourth, the Stokes-Einstein relation holds for temperatures below\n3000 K, but is replaced by a fractional relation above this temperature.\nFurthermore, our data indicate that dynamics become again simple above 5000 K,\nwith Arrhenius behavior and a classical Stokes-Einstein relation."
    },
    {
        "anchor": "Two-dimensional systems with competing interactions: microphase\n  formation under the effect of a disordered porous matrix: We have investigated the effect of a disordered porous matrix on the cluster\nmicrophase formation of a two dimensional system where particles interact via\ncompeting interactions. To this end we have performed extensive Monte Carlo\nsimulations and have systematically varied the densities of the fluid and of\nthe matrix as well as the interaction between the matrix particles and between\nthe matrix and fluid particles. Our results provide evidence that the matrix\ndoes have a distinct effect on the microphase formation of the fluid particles:\nas long as the particles interact both among themselves as well as with the\nfluid particles via a simple hard sphere potential, they essentially reduce the\navailable space, in which the fluid particles form a cluster microphase. On the\nother hand, if we turn on a long-range tail in the matrix-matrix and in the\nmatrix-fluid interactions, the matrix particles become nucleation centers for\nthe clusters formed by the fluid particles.",
        "positive": "Anisotropic short-range attractions precisely model branched erythrocyte\n  aggregates: Homogeneous suspensions of red blood cells (RBCs or erythrocytes) in blood\nplasma are unstable in the absence of driving forces and form elongated stacks,\ncalled rouleau. These erythrocyte aggregates are often branched porous networks\n-- a feature that existing red blood cell aggregation models and simulations\nfail to predict exactly. Here we establish that alignment-dependent attractive\nforces in a system of dimers can precisely generate branched structures similar\nto RBC aggregates observed under a microscope. Our simulations consistently\npredict that the growth rate of typical mean rouleau size remains sub-linear --\na hallmark from past studies -- which we also confirm by deriving a reaction\nkernel taking into account appropriate collision cross-section, approach\nvelocities, and an area-dependent sticking probability. The system exhibits\nunique features such as the existence of percolated and/or single giant cluster\nstates, multiple coexisting mass-size scalings, and transition to a branched\nphase upon fine-tuning of model parameters. Upon decreasing the depletion\nthickness we find that the percolation threshold increases and the morphology\nof the structures opens up towards an increased degree of branching. Remarkably\nthe system self-organizes to produce a universal power-law size distribution\nscaling irrespective of the model parameters."
    },
    {
        "anchor": "Adsorption of polyelectrolytes from semi-dilute solutions on an\n  oppositely charged surface: We propose a detailed description of the structure of the layer formed by\npolyelectrolyte chains adsorbed onto an oppositely charged surface in the\nsemi-dilute regime. We combine the mean-field Poisson-Boltzmann-Edwards theory\nand the scaling functional theory to describe the variations of the monomer\nconcentration, the electrostatic potential, and the local grafting density with\nthe distance to the surface. For long polymers, we find that the effective\ncharge of the decorated surface (surface plus adsorbed polyelectrolytes) can be\nmuch larger than the bare charge of the surface at low salt concentration, thus\nproviding an experimental route to a \"supercharging\" type of effect.",
        "positive": "Wrinkling composite sheets: We examine the buckling shape and critical compression of confined\ninhomogeneous composite sheets lying on a liquid foundation. The buckling modes\nare controlled by the bending stiffness of the sheet, the density of the\nsubstrate, and the size and the spatially dependent elastic coefficients of the\nsheet. We solve the (linearized) F\\\"oppl-von K\\'arm\\'an equations describing\nthe mechanical equilibrium of a sheet when its bending stiffness varies\nparallel to the direction of confinement. The case of a homogeneous bending\nstiffness exhibits a degeneracy of wrinkled states for certain sizes of the\nconfined sheet. This degeneracy disappears for spatially dependent elastic\ncoefficients. Medium length sheets buckle similarly to their homogeneous\ncounterparts, whereas the wrinkled states in large length sheets localize the\nbending energy towards the soft regions of the sheet."
    },
    {
        "anchor": "Rounding of the localization transition in model porous media: The generic mechanisms of anomalous transport in porous media are\ninvestigated by computer simulations of two-dimensional model systems. In order\nto bridge the gap between the strongly idealized Lorentz model and realistic\nmodels of porous media, two models of increasing complexity are considered: a\ncherry-pit model with hard-core correlations as well as a soft-potential model.\nAn ideal gas of tracer particles inserted into these structures is found to\nexhibit anomalous transport which extends up to several decades in time. Also,\nthe self-diffusion of the tracers becomes suppressed upon increasing the\ndensity of the systems. These phenomena are attributed to an underlying\npercolation transition. In the soft potential model the transition is rounded,\nsince each tracer encounters its own critical density according to its energy.\nTherefore, the rounding of the transition is a generic occurrence in realistic,\nsoft systems.",
        "positive": "Exploiting the Hierarchical Morphology of Single-Walled and Multi-Walled\n  Carbon Nanotube Films for Highly Hydrophobic Coatings: Self-assembled hierarchical solid surfaces are very interesting for wetting\nphenomena, as observed in a variety of natural and artificial surfaces. Here,\nwe report single-walled (SWCNT) and multi-walled carbon nanotube (MWCNT) thin\nfilms realized by a simple, rapid, reproducible, and inexpensive filtration\nprocess from an aqueous dispersion, that was deposited at room temperature by a\ndry-transfer printing method on glass. Furthermore, the investigation of carbon\nnanotube films through scanning electron microscopy (SEM) reveals the\nmulti-scale hierarchical morphology of the self-assembled carbon nanotube\nrandom networks. Moreover, contact angle measurements show that hierarchical\nSWCNT/MWCNT composite surfaces exhibit a higher hydrophobicity (contact angles\nof up to 137{\\deg}) than bare SWCNT (110{\\deg}) and MWCNT (97{\\deg}) coatings,\nthereby confirming the enhancement produced by the surface hierarchical\nmorphology."
    },
    {
        "anchor": "Drift of a polymer chain in disordered media: We consider the drift of a polymer chain in a disordered medium, which is\ncaused by a constant force applied to the one end of the polymer, under\nneglecting the thermal fluctuations. In the lowest order of the perturbation\ntheory we have computed the transversal fluctuations of the centre of mass of\nthe polymer, the transversal and the longitudinal size of the polymer, and the\naverage velocity of the polymer. The corrections to the quantities under\nconsideration, which are due to the interplay between the motion and the\nquenched forces, are controlled by the driving force and the degree of\npolymerization. The transversal fluctuations of the Brownian particle and of\nthe centre of mass of the polymer are obtained to be diffusive. The transversal\nfluctuations studied in the present Letter may also be of relevance for the\nrelated problem of the drift of a directed polymer in disordered media and its\napplications.",
        "positive": "Defects in Conformal Crystals: Discrete vs. Continuous Disclination\n  Models: We study the relationship between topological defect formation and\nground-state packings in a model of repulsions in external confining\npotentials. Specifically we consider screened 2D Coulombic repulsions, which\nconveniently parameterizes the effects of interaction range, but also serves as\nsimple physical model of confined, parallel arrays of polyelectrolyte filaments\nor vortices in type-II superconductors. The countervailing tendencies of\nrepulsions and confinement to, respectively, spread and concentrate particle\ndensity leads to an energetic preference for non-uniform densities in the\nclusters. Ground states in such systems have previously been modeled as {\\it\nconformal crystals}, which are composed of locally equitriangular packings\nwhose local areal densities exhibit long range gradients. Here, we assess two\ntheoretical models that connect the preference for non-uniform density to the\nformation of disclination defects, one of which assumes a continuum\ndistributions of defect, while the second considers the quantized and localized\nnature of disclinations in hexagonal conformal crystals. Comparing both models\nto numerical simulations of discrete particles clusters, we study the influence\nof interaction range and confining potential on defects in ground states. We\nshow that treating disclinations as continuously distributable well-captures\nthe number of topological defects in the ground state in the regime of\nlong-range interactions, while as interactions become shorter range, it\ndramatically overpredicts the to growth in total defect charge. Analysis of the\ndiscretized defect theory suggests that limitations of the continuous defect\ntheory can be attributed to the asymmetry in the placement of positive vs.\nnegative disclinations in the conformal crystal ground states, as well as a\nstrongly asymmetric dependence of self-energy of disclinations on sign of\ntopological charge."
    },
    {
        "anchor": "On the rupture of DNA molecule: Using Langevin Dynamic simulations, we study effects of the shear force on\nthe rupture of a double stranded DNA molecule. The model studied here contains\ntwo single diblock copolymers interacting with each other. The elastic\nconstants of individual segments of the diblock copolymer are considered to be\ndifferent. We showed that the magnitude of the rupture force depends on whether\nthe force is applied at $3'-3'-$ends or $5'-5'-$ends. Distributions of\nextension in hydrogen bonds and covalent bonds along the chain show the\nstriking differences. Motivated by recent experiments, we have also calculated\nthe variation of rupture force for different chain lengths. Results obtained\nfrom simulations have been validated with the analytical calculation based on\nthe ladder model of DNA.",
        "positive": "Diblock Copolymer Ordering Induced by Patterned Surfaces Above the\n  Order-Disorder Transition: We investigate the morphology of diblock copolymers in the vicinity of flat,\nchemically patterned surfaces. Using a Ginzburg-Landau free energy, spatial\nvariations of the order parameter are given in terms of a general\ntwo-dimensional surface pattern above the order-disorder transition. The\npropagation of several surface patterns into the bulk is investigated. The\noscillation period and decay length of the surface $q$-modes are calculated in\nterms of system parameters. We observe lateral order parallel to the surface as\na result of order perpendicular to the surface. Surfaces which has a finite\nsize chemical pattern (e.g., a stripe of finite width) induces lamellar\nordering extending into the bulk. Close to the surface pattern the lamellae are\nstrongly perturbed adjusting to the pattern."
    },
    {
        "anchor": "An Efficient Algorithm for Topological Characterisation of Worm-Like and\n  Branched Micelle Structures from Simulations: Many surfactant-based formulations are utilised in industry as they produce\ndesirable visco-elastic properties at low-concentrations. These properties are\ndue to the presence of worm-like micelles (WLM) and, as a result, understanding\nthe processes that lead to WLM formation is of significant interest. Various\nexperimental techniques have been applied with some success to this problem but\ncan encounter issues probing key microscopic characteristics or the specific\nregimes of interest. The complementary use of computer simulations could\nprovide an alternate route to accessing their structural and dynamic behaviour.\nHowever, few computational methods exist for measuring key characteristics of\nWLMs formed in particle simulations. Further, their mathematical formulation\nare challenged by WLMs with sharp curvature profiles or density fluctuations\nalong the backbone. Here we present a new topological algorithm for identifying\nand characterising WLMs micelles in particle simulations which has desirable\nmathematical properties that address short-comings in previous techniques. We\napply the algorithm to the case of Sodium dodecyl sulfate (SDS) micelles to\ndemonstrate how it can be used to construct a comprehensive topological\ncharacterisation of the observed structures.",
        "positive": "Dynamics of silo deformation under granular discharge: We use Topological Data Analysis to study the post buckling behavior of\nlaboratory scale cylindrical silos under gravity driven granular discharges.\nThin walled silos buckle during the discharge if the initial height of the\ngranular column is large enough. The deformation of the silo is reversible as\nlong as the filling height does not exceed a critical value, $L_c$. Beyond this\nthreshold the deformation becomes permanent and the silo often collapses. We\nstudy the dynamics of reversible and irreversible deformation processes,\nvarying the initial filling height around $L_c$. We find that all reversible\nprocesses exhibit striking similarities and they alternate between regimes of\nslow and fast dynamics. The patterns that occur at the beginning of\nirreversible deformation processes are topologically very similar to those that\narise during reversible processes. However, the dynamics of reversible and\nirreversible processes is significantly different. In particular, the evolution\nof irreversible processes is much faster. This allows us to make an early\nprediction of the collapse of the silo based solely on observations of the\ndeformation patterns."
    },
    {
        "anchor": "Deficiencies in numerical models of anisotropic nonlinearly elastic\n  materials: Incompressible nonlinearly hyperelastic materials are rarely simulated in\nFinite Element numerical experiments as being perfectly incompressible because\nof the numerical difficulties associated with globally satisfying this\nconstraint. Most commercial Finite Element packages therefore assume that the\nmaterial is slightly compressible. It is then further assumed that the\ncorresponding strain-energy function can be decomposed additively into\nvolumetric and deviatoric parts. We show that this decomposition is not\nphysically realistic, especially for anisotropic materials, which are of\nparticular interest for simulating the mechanical response of biological soft\ntissue. The most striking illustration of the shortcoming is that with this\ndecomposition, an anisotropic cube under hydrostatic tension deforms into\nanother cube instead of a hexahedron with non-parallel faces. Furthermore,\ncommercial numerical codes require the specification of a `compressibility\nparameter' (or `penalty factor'), which arises naturally from the flawed\nadditive decomposition of the strain-energy function. This parameter is often\nlinked to a `bulk modulus', although this notion makes no sense for anisotropic\nsolids; we show that it is essentially an arbitrary parameter and that\ninfinitesimal changes to it result in significant changes in the predicted\nstress response. This is illustrated with numerical simulations for biaxial\ntension experiments of arteries, where the magnitude of the stress response is\nfound to change by several orders of magnitude when infinitesimal changes in\n`Poisson's ratio' close to the perfect incompressibility limit of 1/2 are made.",
        "positive": "Identification of structure in condensed matter with the topological\n  cluster classification: We describe the topological cluster classification (TCC) algorithm. The TCC\ndetects local structures with bond topologies similar to isolated clusters\nwhich minimise the potential energy for a number of monatomic and binary simple\nliquids with $m\\leq13$ particles. We detail a modified Voronoi bond detection\nmethod that optimizes the cluster detection. The method to identify each\ncluster is outlined, and a test example of Lennard-Jones liquid and crystal\nphases is considered and critically examined."
    },
    {
        "anchor": "Real-time visualization of metastable charge regulation pathways in\n  molecularly confined slit geometries: Transport of ions in molecular-scale confined spaces is central to all\naspects of life and technology: into a crack, it may break steel within days;\nthrough a membrane separator, it determines the efficiency of electrochemical\nenergy conversion devices; or through lipid membranes, it steers neural\ncommunication. Yet, the direct observation of ion mobility and structuring in\nsub-nanometer confinement is experimentally challenging and, so far, solely\naccessible to molecular simulations. Here, we show quantitative, 3D\nmolecularly-resolved ion transportation of aqueous ionic liquid and s-block\nmetal ion solutions, confined to electrochemically-modulated, molecular-sized\nslits. Our analysis of atomically resolved solid/liquid interface unveils\ngeneric rules of how enthalpic ion-ion and ion-surface interactions and\nentropic confinement effects determine the charge regulation mechanism.\nAltering our general understanding, the confined charge regulation may proceed\nvia fast, kinetically favoured, metastable pathways, followed by slow diffusive\nthermodynamic ion reorganization, which has important implications for all\ncharge-regulated systems.",
        "positive": "Screening of Hydrodynamic Interactions in Semidilute Polymer Solutions:\n  A Computer Simulation Study: We study single-chain motion in semidilute solutions of polymers of length N\n= 1000 with excluded-volume and hydrodynamic interactions by a novel algorithm.\nThe crossover length of the transition from Zimm (short lengths and times) to\nRouse dynamics (larger scales) is proportional to the static screening length.\nThe crossover time is the corresponding Zimm time. Our data indicate Zimm\nbehavior at large lengths but short times. There is no hydrodynamic screening\nuntil the chains feel constraints, after which they resist the flow:\n\"Incomplete screening\" occurs in the time domain."
    },
    {
        "anchor": "Monte Carlo Simulations of Novel Biaxial Ordering in Systems of\n  Uniaxially Interacting Rod-like Ellipsoids: The minimal ingredient to generate a biaxial liquid crystalline ordering is\nusually considered to be the strongly biaxial interactions breaking the\ncylindrical symmetry of the uniaxial molecules. Although there is no\nfundamental reason to forbid a biaxial ordering of pure uniaxial origin, it has\nbeen a long standing problem to find a robust demonstration of such phenomenon\nin systems of rod-like particles. We report here off-lattice Monte Carlo\nsimulations of some new model systems of polar achiral rodlike ellipsoids which\nspontaneously exhibit novel biaxial smectic phases of pure uniaxial origin. We\nshow that dipolar interactions can generate different biaxial phases of pure\nuniaxial origin in systems of cylindrically symmetric Gay-Berne ellipsoids for\nan wide variety of length-to-width ratios. The systems of ellipsoids with low\nlength-to-width ratios exhibit highly tilted biaxial smectic phases in the\npresence of central axial dipoles. In case of ellipsoids having high\nlength-to-width ratio, the generation of a biaxial phase requires the presence\nof two parallel axial terminal dipoles. In addition, the phases also exhibit\nfascinating ferroelectric or striped ordering of the dipolar ellipsoids.",
        "positive": "Templated self-assembly of patchy particles: We explore the use of templated self-assembly to facilitate the formation of\ncomplex target structures made from patchy particles. First, we consider the\ntemplating of high-symmetry shell structures around a spherical core particle.\nWe find that nucleation around the core particle can inhibit aggregate\nformation, a process which often hinders self-assembly. In particular, this new\nassembly pathway allows dodecahedral shells to form readily, whereas these\nstructures never form in the absence of the template. Secondly, we consider the\nself-assembly of multi-shell structures, where the central icosahedral core is\nknown to form readily on its own, and which could then template the growth of\nfurther layers. We are able to find conditions under which two- and three-shell\nstructures successfully assemble, illustrating the power of the templating\napproach."
    },
    {
        "anchor": "Dynamics of sedimenting active Brownian particles: We investigate the stochastic dynamics of one sedimenting active Brownian\nparticle in three dimensions under the influence of gravity and passive\nfluctuations in the translational and rotational motion. We present an\nanalytical solution of the Fokker--Planck equation for the stochastic process\nwhich allows us to describe the dynamics of the active Brownian particle in\nthree dimensions. We address the time evolution of the monopole, the\npolarization, and the steady-state solution. We also perform Brownian dynamics\nsimulations and study the effect of the activity of the particles on their\ncollective motion. These results qualitatively agree with our model. Finally,\nwe compare our results with experiments [J. Palacci \\emph{et al.}, Phys. Rev.\nLett. \\textbf{105}, 088304 (2010)] and find very good agreement.",
        "positive": "Strong geometric frustration in model glassformers: We consider three popular model glassformers, the Kob-Andersen and\nWahnstr\\\"om binary Lennard-Jones models and weakly polydisperse hard spheres.\nAlthough these systems exhibit a range of fragilities, all feature a rather\nsimilar behaviour in their local structure approaching dynamic arrest. In\nparticular we use the dynamic topological cluster classification to extract a\nlocally favoured structure which is particular to each system. These structures\nform percolating networks, however in all cases there is a strong decoupling\nbetween structural and dynamic lengthscales. We suggest that the lack of growth\nof the structural lengthscale may be related to strong geometric frustration."
    },
    {
        "anchor": "Stress Propagation through Frictionless Granular Material: We examine the network of forces to be expected in a static assembly of hard,\nfrictionless spherical beads of random sizes, such as a colloidal glass. Such\nan assembly is minimally connected: the ratio of constraint equations to\ncontact forces approaches unity for a large assembly. However, the bead\npositions in a finite subregion of the assembly are underdetermined. Thus to\nmaintain equilibrium, half of the exterior contact forces are determined by the\nother half. We argue that the transmission of force may be regarded as\nunidirectional, in contrast to the transmission of force in an elastic\nmaterial. Specializing to sequentially deposited beads, we show that forces on\na given buried bead can be uniquely specified in terms of forces involving more\nrecently added beads. We derive equations for the transmission of stress\naveraged over scales much larger than a single bead. This derivation requires\nthe Ansatz that statistical fluctuations of the forces are independent of\nfluctuations of the contact geometry. Under this Ansatz, the\n$d(d+1)/2$-component stress field can be expressed in terms of a d-component\nvector field. The procedure may be generalized to non-sequential packings. In\ntwo dimensions, the stress propagates according to a wave equation, as\npostulated in recent work elsewhere. We demonstrate similar wave-like\npropagation in higher dimensions, assuming that the packing geometry has\nuniaxial symmetry. In macroscopic granular materials we argue that our approach\nmay be useful even though grains have friction and are not packed\nsequentially.=17",
        "positive": "Self-emulsification in chemical and pharmaceutical technologies: The interest in the low energy self-emulsification techniques has exploded in\nthe recent years, driven by three main trends: by the transition to \"greener\"\ntechnologies in both its aspects - less energy consumption and replacement of\nthe petrochemicals by natural ingredients; by the costly and maintenance\ndemanding equipment for nanoemulsification; and by the quest for efficient and\nrobust self-emulsifying formulations for oral drug delivery. Here we first\npresent a brief overview of the main known low-energy methods for nanoemulsion\nformation, focusing on their mechanistic understanding and discussing some\nrecent advances in their development and applications. Next, we review three\nconceptually new approaches for self-emulsification in chemical technologies,\ndiscovered in the last several years. The colloidal features and the specific\nrequirements of the self-emulsifying drug-delivery systems (SEDDS) are also\ndiscussed briefly. Finally, we summarize the current trends and the main\nchallenges in this vivid research area."
    },
    {
        "anchor": "Stationary shapes of axisymmetric vesicles beyond lowest-energy\n  configurations: We conduct a systematic exploration of the energy landscape of vesicle\nmorphologies within the framework of the Helfrich model. Vesicle shapes are\ndetermined by minimizing the elastic energy subject to constraints of constant\narea and volume. The results show that pressurized vesicles can adopt\nhigher-energy spindle-like configurations that require the action of point\nforces at the poles. If the internal pressure is lower than the external one,\nmultilobed shapes are predicted. We utilize our results to rationalize the\nexperimentally observed spindle shapes of giant vesicles in a uniform AC field.",
        "positive": "Tunable Shape Oscillations of Adaptive Droplets: Living materials adapt their shape to signals from the environment, yet the\nimpact of shape changes on signal processing and the associated feedback\ndynamics remain unclear. We derive coarse-grained equations for droplets that\nadjust their interfacial tension in response to signals exchanged at contact\nsurfaces, from the microscopic biophysics of adhesion and signaling. We find\nthat droplet pairs exhibit symmetry-breaking, excitability, and oscillations.\nThe underlying critical points reveal novel mechanisms for physical signal\nprocessing through shape adaptation in soft active materials."
    },
    {
        "anchor": "Validity of the linear viscoelastic model for a polymer cylinder with\n  ultrasonic hysteresis-type absorption in a nonviscous fluid: A necessary condition for the validity of the linear viscoelastic model for a\n(passive) polymeric cylinder with an ultrasonic hysteresis-type absorption\nsubmerged in a non-viscous fluid requires that the absorption efficiency is\npositive (Qabs > 0) satisfying the law of the conservation of energy. This\ncondition imposes restrictions on the values attributed to the normalized\nabsorption coefficients for the compressional and shear-wave wavenumbers for\neach partial-wave mode n. The forbidden values produce negative axial radiation\nforce, absorption and extinction efficiencies, as well as an enhancement of the\nscattering efficiency, not in agreement with the conservation of energy law.\nNumerical results for the radiation force, extinction, absorption and\nscattering efficiencies are performed for three viscoelastic (VE) polymer\ncylinders immersed in a non-viscous host liquid (i.e. water) with particular\nemphasis on the shear-wave absorption coefficient of the cylinder, the\ndimensionless size parameter and the partial-wave mode number n. Mathematical\nconstraints are established for the non-dimensional absorption coefficients of\nthe longitudinal and shear waves for a cylinder (i.e. 2D case) and a sphere\n(i.e. 3D case) in terms of the sound velocities in the VE material. The\nanalysis suggests that the domain of validity for any viscoelastic model\ndescribing acoustic attenuation inside a lossy cylinder (or sphere) in a\nnon-viscous fluid must be verified based upon the optical theorem.",
        "positive": "Profile blunting and flow blockage in a yield stress fluid: A molecular\n  dynamics study: The flow of a simple glass forming system (a 80:20 binary Lennard-Jones\nmixture) through a planar channel is studied via molecular dynamics\nsimulations. The flow is driven by an external body force similar to gravity.\nPrevious studies show that the model exhibits both a static [Varnik et al. J.\nChem. Phys. 120, 2788 (2004)] and a dynamic [F. Varnik and O. Henrich Phys.\nRev. B 73, 174209 (2006)] yield stress in the glassy phase. \\blue{These\nobservations are corroborated by the present work, where we investigate how the\npresence of a yield stress may affect the system behavior in a Poiseuille-type\nflow geometry.} In particular, we observe a blunted velocity profile across the\nchannel: A relatively wide region in the channel center flows with a constant\nvelocity (zero shear rate) followed by a non linear change of the shear rate as\nthe walls are approached. The observed velocity gradients are compared to those\nobtained from the knowledge of the shear stress across the channel and the\nflow-curves (stress versus shear rate), the latter being determined in our\nprevious simulations of homogeneous shear flow. Furthermore, using the value of\nthe (dynamic) yield stress known from previous simulations, we estimate the\nthreshold body force for a complete arrest of the flow. Indeed, a blockage is\nobserved as the imposed force falls below this threshold value. Small but\nfinite shear rates are observed at stresses above the dynamic but below the\nstatic yield stress. We discuss the possible role of the \\blue{stick-slip like\nmotion} for this observation."
    },
    {
        "anchor": "A Lattice Model for Colloidal Gels and Glasses: We study a lattice model of attractive colloids. It is exactly solvable on\nsparse random graphs. As the pressure and temperature are varied it reproduces\nmany characteristic phenomena of liquids, glasses and colloidal systems such as\nideal gel formation, liquid-glass phase coexistence, jamming, or the reentrance\nof the glass transition.",
        "positive": "Overcharging and reentrant condensation of thermoresponsive ionic\n  microgels: We investigated the complexation of thermoresponsive anionic\npoly(N-isopropylacrylamide) (PNiPAM) microgels and cationic\n$\\epsilon$-polylysine ($\\epsilon$-PLL) chains. By combining electrophoresis,\nlight scattering, transmission electron microscopy (TEM) and dielectric\nspectroscopy (DS) we studied the adsorption of $\\epsilon$-PLL onto the microgel\nnetworks and its effect on the stability of the suspensions. We show that the\nvolume phase transition (VPT) of the microgels triggers a large polyion\nadsorption. Two interesting phenomena with unique features occur: a\ntemperature-dependent microgel overcharging and a complex reentrant\ncondensation. The latter may occur at fixed polyion concentration, when\ntemperature is raised above the VPT of microgels, or by increasing the number\ndensity of polycations at fixed temperature. TEM and DS measurements\nunambiguously show that short PLL chains adsorb onto microgels and act as\nelectrostatic glue above the VPT. By performing thermal cycles, we further show\nthat polyion-induced clustering is a quasi-reversible process: within the time\nof our experiments large clusters form above the VPT and partially re-dissolve\nas the mixtures are cooled down. Finally we give a proof that the observed\nphenomenology is purely electrostatic in nature: an increase of the ionic\nstrength gives rise to the polyion desorption from the microgel outer shell."
    },
    {
        "anchor": "Universality and stability phase-diagram of two-dimensional brittle\n  fracture: The two-dimensional oscillatory crack instability, experimentally observed in\na class of brittle materials under strongly dynamic conditions, has been\nrecently reproduced by a nonlinear phase-field fracture theory. Here we\nhighlight the universal character of this instability by showing that it is\npresent in materials exhibiting widely different near crack tip elastic\nnonlinearity, and by demonstrating that the oscillations wavelength follows a\nuniversal master curve in terms of dissipation-related and nonlinear elastic\nintrinsic length scales. Moreover, we show that upon increasing the driving\nforce for fracture, a high-velocity tip-splitting instability emerges, as\nexperimentally demonstrated. The analysis culminates in a comprehensive\nstability phase-diagram of two-dimensional brittle fracture, whose salient\nproperties and topology are independent of the form of near tip nonlinearity.",
        "positive": "Energetics of active fluctuations in living cells: The nonequilibrium activity taking place in a living cell can be monitored\nwith a tracer embedded in the medium. While microrheology experiments based on\noptical manipulation of such probes have become increasingly standard, we put\nforward a number of experiments with alternative protocols that, we claim, will\nprovide new insight into the energetics of active fluctuations. These are based\non either performing thermodynamic--like cycles in control-parameter space, or\non determining response to external perturbations of the confining trap beyond\nsimple translation. We illustrate our proposals on an active itinerant Brownian\noscillator modeling the dynamics of a probe embedded in a living medium."
    },
    {
        "anchor": "Self-assembly of amphiphilic peanut-shaped nanoparticles: We use computer simulation to investigate the self-assembly of Janus-like\namphiphilic peanut-shaped nanoparticles, finding phases of clusters, bilayers\nand micelles in accord with ideas of packing familiar from the study of\nmolecular surfactants. However, packing arguments do not explain the\nhierarchical self-assembly dynamics that we observe, nor the coexistence of\nbilayers and faceted polyhedra. This coexistence suggests that experimental\nrealizations of our model can achieve multipotent assembly of either of two\ncompeting ordered structures.",
        "positive": "Finite-time collapse and soliton-like states in the dynamics of\n  dissipative gases: A study of the gas dynamics of a dilute collection of the inelastically\ncolliding hard spheres is presented. When diffusive processes are neglected the\ngas density blows up in a finite time. The blowup is the mathematical\nexpression for one of the possible mechanisms for cluster formation in\ndissipative gases. The way diffusive processes smoothen the singularity has\nbeen studied. Exact localized soliton-type solutions of the gas dynamics when\nheat diffusion balances non-linear cooling are obtained. The presented results\ngeneralize previous findings for planar flows."
    },
    {
        "anchor": "The renormalized Jellium model of colloidal suspensions with multivalent\n  counterions: An extension of the renormalized Jellium model which allows to study\ncolloidal suspensions containing trivalent counterions is proposed. The theory\nis based on a modified Poisson-Boltzmann equation which incorporates the\neffects of counterion correlations near the colloidal surfaces using a new\nboundary condition. The renormalized charges, the counterion density profiles,\nand osmotic pressures can be easily calculated using the modified renormalized\nJellium model. The results are compared with the ones obtained using the\ntraditional Wigner-Seitz (WS) cell approximation also with a new boundary\ncondition. We find that while the thermodynamic functions obtained within the\nrenormalized Jellium model are in a good agreement with their WS counterpart,\nthe effective charges predicted by the two theories can be significantly\ndifferent.",
        "positive": "Growth of Form in Thin Elastic Structures: Heterogeneous growth plays an important role in the shape and pattern\nformation of thin elastic structures ranging from the petals of blooming lilies\nto the cell walls of growing bacteria. Here we address the stability and\nregulation of such growth, which we modeled as a quasi-static time evolution of\na metric, with fast elastic relaxation of the shape. We consider regulation via\ncoupling of the growth law, defined by the time derivative of the target\nmetric, to purely local properties of the shape, such as the local curvature\nand stress. For cylindrical shells, motivated by rod-like E. \\textit{coli}, we\nshow that coupling to curvature alone is generically linearly unstable and that\nadditionally coupling to stress can lead to stably elongating structures. Our\napproach can readily be extended to gain insights into the general classes of\nstable growth laws for different target geometries."
    },
    {
        "anchor": "Inverse design of deployable origami structures that approximate a\n  general surface: Shape-morphing finds widespread utility, from the deployment of small stents\nand large solar sails to actuation and propulsion in soft robotics. Origami\nstructures provide a template for shape-morphing, but rules for designing and\nfolding the structures are challenging to integrate into broad and versatile\ndesign tools. Here, we develop a sequential two-stage optimization framework to\napproximate a general surface by a deployable origami structure. The\noptimization is performed over the space of all possible rigidly and\nflat-foldable quadrilateral mesh origami. So, the origami structures produced\nby our framework come with desirable engineering properties: they can be easily\nmanufactured on a flat reference sheet, deployed to their target state by a\ncontrolled folding motion, then to a compact folded state in applications\ninvolving storage and portability. The attainable surfaces demonstrated include\nthose with modest but diverse curvatures and unprecedented ones with sharp\nridges. The framework provides not only a tool to design various deployable and\nretractable surfaces in engineering and architecture, but also a route to\noptimizing other properties and functionality.",
        "positive": "TransPath: A Computational Method to Study the Ion Transit Pathways in\n  Membrane Channels: The finely tuned structures of membrane channels allow selective passage of\nions through the available aqueous pores. In order to understand channel\nfunction, it is crucial to locate the pore and study its physical and chemical\nproperties. Recently obtained X-ray crystal structures of bacterial chloride\nchannel homologues reveal a complicated topology with curvilinear pores. The\ncommonly used HOLE program encounters difficulties in studying such pores. Here\nwe propose a new pore-searching algorithm (TransPath) which uses the\nConfigurational Bias Monte Carlo (CBMC) method to generate transmembrane\ntrajectories driven by both geometric and electrostatic features. The\ntrajectories are binned into groups determined by a vector distance criterion.\n  From each group, a representative trajectory is selected based on the\nRosenbluth weight, and the geometrically optimal path is obtained by simulated\nannealing. Candidate ion pathways can then be determined by analysis of the\nradius and potential profiles. The proposed method and its implementation are\nillustrated using the bacterial KcsA potassium channel as an example. The\nprocedure is then applied to the more complex structures of the bacterial E.\ncoli ClC channel homologues."
    },
    {
        "anchor": "Phase diagram of Kob-Andersen type binary Lennard-Jones mixtures: The binary Kob-Andersen (KA) Lennard-Jones mixture is the standard model for\ncomputational studies of viscous liquids and the glass transition. For very\nlong simulations the viscous KA system crystallizes, however, by phase\nseparating into a pure A particle phase forming an FCC crystal. We present the\nthermodynamic phase diagram for KA-type mixtures consisting of up to 50\\% small\n(B) particles showing, in particular, that the melting temperature of the\nstandard KA system at liquid density $1.2$ is $1.028(3)$ in A particle\nLennard-Jones units. At large B particle concentrations the system crystallizes\ninto the CsCl crystal structure. The eutectic corresponding to the FCC and CsCl\nstructures is cut-off in a narrow interval of B particle concentrations around\n26\\% at which the bipyramidal orthorhombic ${\\rm PuBr_3}$ structure is the\nthermodynamically stable phase. The melting temperature's variation with B\nparticle concentration at two other pressures, as well as at the constant\ndensity $1.2$, is estimated from the simulations at pressure $10.19$ using\nisomorph theory. Our data demonstrate approximate identity between the melting\ntemperature and the onset temperature below which viscous dynamics appears.\nFinally, the nature of the solid-liquid interface is briefly discussed.",
        "positive": "Structural Signature of Slow and Heterogeneous Dynamics in Glass-Forming\n  Liquids: One of the central problems of the liquid-glass transition is whether there\nis a structural signature that can qualitatively distinguish different dynamic\nbehaviors at different degrees of supercooling. Here, we propose a novel\nstructural characterization based on the spatial correlation of local density\nand we show the locally dense-packed structural environment has a direct link\nwith the slow dynamics as well as dynamic heterogeneity in glass-formers. We\nfind that particles with large local density relax slowly and the size of\ncluster formed by the dense-packed particles increases with decreasing the\ntemperature. Moreover, the extracted static length scale shows clear\ncorrelation with the relaxation time at different degrees of supercooling. This\nsuggests that the temporarily but continuously formed locally dense-packed\nstructural environment may be the structural origin of slow dynamics and\ndynamic heterogeneity of the glass-forming liquids."
    },
    {
        "anchor": "Interfacial Stresses on Droplet Interface Bilayers Using Two Photon\n  Fluorescence Lifetime Imaging Microscopy: Response of lipid bilayers to external mechanical stimuli is an active area\nof research with implications for fundamental and synthetic cell biology.\nHowever, there is a lack of tools for systematically imposing mechanical\nstrains and non-invasively mapping out interfacial (membrane) stress\ndistributions on lipid bilayers. In this article, we report a miniature\nplatform to manipulate model cell membranes in the form of droplet interface\nbilayers (DIBs), and non-invasively measure spatio-temporally resolved\ninterfacial stresses using two photon fluorescence lifetime imaging of an\ninterfacially active molecular flipper (Flipper-TR). We established the\neffectiveness of the developed framework by investigating interfacial stresses\naccompanying three key processes associated with DIBs: thin film drainage\nbetween lipid monolayer coated droplets, bilayer formation, and bilayer\nseparation. Interestingly, the measurements also revealed fundamental aspects\nof DIBs including the existence of a radially decaying interfacial stress\ndistribution post bilayer formation, and the simultaneous build up and decay of\nstress respectively at the bilayer corner and center during bilayer separation.\nFinally, utilizing interfacial rheology measurements and MD simulations, we\nalso reveal that the tested molecular flipper is sensitive to membrane fluidity\nthat changes with interfacial stress - expanding the scientific understanding\nof how molecular motors sense stress.",
        "positive": "Connectivity percolation in suspensions of hard platelets: We present a study on connectivity percolation in suspensions of hard\nplatelets by means of Monte Carlo simulation. We interpret our results using a\ncontact-volume argument based on an effective single--particle cell model. It\nis commonly assumed that the percolation threshold of anisotropic objects\nscales as their inverse aspect ratio. While this rule has been shown to hold\nfor rod-like particles, we find that for hard plate-like particles the\npercolation threshold is non-monotonic in the aspect ratio. It exhibits a\nshallow minimum at intermediate aspect ratios and then saturates to a constant\nvalue. This effect is caused by the isotropic-nematic transition pre-empting\nthe percolation transition. Hence the common strategy to use highly\nanisotropic, conductive particles as fillers in composite materials in order to\nproduce conduction at low filler concentration is expected to fail for\nplate-like fillers such as graphene and graphite nanoplatelets."
    },
    {
        "anchor": "Aging to non-Newtonian hydrodynamics in a granular gas: The evolution to the steady state of a granular gas subject to simple shear\nflow is analyzed by means of computer simulations. It is found that, regardless\nof its initial preparation, the system reaches (after a transient period\nlasting a few collisions per particle) a non-Newtonian (unsteady) hydrodynamic\nregime, even at strong dissipation and for states where the time scale\nassociated with inelastic cooling is shorter than the one associated with the\nirreversible fluxes. Comparison with a simplified rheological model shows a\ngood agreement.",
        "positive": "Collective motion of active particles exhibiting non-reciprocal\n  orientational interactions: We present a Brownian dynamics study of a 2d bath of active particles\ninteracting among each other through usual steric interactions and,\nadditionally, via non-reciprocal avoidant orientational interactions. We\nmotivate them by the fact that the two flagella of the alga Chlamydomonas\ninteract sterically with nearby surfaces such that a torque acts on the alga.\nAs expected, in most cases such interactions disrupt the motility-induced\nparticle clustering in active baths. Surprisingly, however, we find that the\nactive particles can self-organize into collectively moving flocks if the range\nof non-reciprocal interactions is close to that of steric interactions. We\nobserve that the flocking motion can manifest itself through a variety of\nstructural forms, spanning from single dense bands to multiple moderately-dense\nstripes, which are highly dynamic. The flocking order parameter is found to be\nonly weakly dependent on the underlying flock structure. Together with the\nvariance of the local-density distribution, one can clearly group the flocking\nmotion into the two separate band and dynamic-stripes states."
    },
    {
        "anchor": "Nonlinear DC-response in Composites: a Percolative Study: The DC-response, namely the $I$-$V$ and $G$-$V$ charateristics, of a variety\nof composite materials are in general found to be nonlinear. We attempt to\nunderstand the generic nature of the response charactersistics and study the\npeculiarities associated with them. Our approach is based on a simple and\nminimal model bond percolative network. We do simulate the resistor network\nwith appropritate linear and nonlinear bonds and obtain macroscopic nonlinear\nresponse characteristics. We discuss the associated physics. An effective\nmedium approximation (EMA) of the corresponding resistor network is also given.",
        "positive": "Pure measure of bending for soft plates: This paper, originally motivated by a question raised by Wood and Hanna [Soft\nMatter, 15, 2411 (2019)], shows that pure measures of bending for soft plates\ncan be defined by introducing the class of bending-neutral deformations, finite\nincremental changes of the plate's shape bearing no further bending. This class\nof deformations is subject to a geometric compatibility condition, which is\nfully characterized. A tensorial pure measure of bending, which is accordingly\ninvariant under bending-neutral deformations, is described in details. As shown\nby an illustrative class of examples, the general notion of pure measure of\nbending could be of use to formulate direct theories for soft plates, where\nstretching and bending energies are kept separate."
    },
    {
        "anchor": "Dynamical Facilitation Governs the Equilibration Dynamics of Glasses: Convincing evidence of domain growth in the heating of ultrastable glasses\nsuggests that the equilibration dynamics of super-cooled liquids could be\ndriven by a nucleation and growth mechanism. We investigate this possibility by\nsimulating the equilibration dynamics of a model glass during both heating and\ncooling between poorly and well-annealed states. Though we do observe the\ngrowth of domains during heating, we find that domains are absent during\ncooling. This absence is inconsistent with classical nucleation theory. By\ncomparing the equilibration dynamics of our glass with that of two models with\nkinetic constraints, we demonstrate that dynamical facilitation generically\nleads to heating driven by domain growth and cooling without domains. Our\nresults provide strong evidence that dynamical facilitation, not nucleation and\ninterfacial-tension-driven domain growth, is the driving mechanism for the\nequilibration dynamics of glass-formers.",
        "positive": "Surface growth effects on reactive capillary-driven flow: Lattice\n  Boltzmann investigation: The Washburn law has always played a critical role for ceramics. In the\nmicroscale, surface forces take over volume forces and the phenomenon of\nspontaneous infiltration in narrow interstices becomes of particular relevance.\nThe Lattice Boltzmann method is applied in order to ascertain the role of\nsurface reaction and subsequent deformation of a single capillary in 2D for the\nlinear Washburn behavior. The proposed investigation is motivated by the\nproblem of reactive infiltration of molten silicon into carbon preforms. This\nis a complex phenomenon arising from the interplay between fluid flow, the\ntransition to wetting, surface growth and heat transfer. Furthermore, it is\ncharacterized by slow infiltration velocities in narrow interstices resulting\nin small Reynolds numbers that are difficult to reproduce with a single\ncapillary. In our simulations, several geometric characteristics for the\ncapillaries are considered, as well as different infiltration and reaction\nconditions. The main result of our work is that the phenomenon of pore closure\ncan be regarded as independent of the infiltration velocity, and in turn a\nnumber of other parameters. The instrumental conclusion drawn from our\nsimulations is that short pores with wide openings and a round-shaped\nmorphology near the throats represent the optimal configuration for the\nunderlying structure of the porous preform in order to achieve faster\ninfiltration. The role of the approximations is discussed in detail and the\nrobustness of our findings is assessed."
    },
    {
        "anchor": "Helical microstructures in molluscan biomineralization are a biological\n  example of close packed helices that may form from a colloidal liquid crystal\n  precursor in a twist-bend nematic phase: We demonstrate that nature has produced a close-packed helical twisted\nfilamentous material in the biomineralization of the mollusc. In liquid\ncrystals, twist-bend nematics have been predicted and observed. We present and\nanalyse evidence that the helical biomineral microstructure of mollusc shells\nmay be formed from such a liquid-crystal precursor.",
        "positive": "Chirality separation of mixed chiral microswimmers in a periodic channel: Dynamics and separation of mixed chiral microswimmers are numerically\ninvestigated in a channel with regular arrays of rigid half-circle obstacles.\nFor zero shear flow, transport behaviors are the same for different chiral\nparticles: the average velocity decreases with increase of the rotational\ndiffusion coefficient, the direction of the transport can be reversed by tuning\nthe angular velocity, and there exists an optimal value of the packing fraction\nat which the average velocity takes its maximal value. However, when the shear\nflow is considered, different chiral particles show different behaviors. By\nsuitably tailoring parameters, particles with different chiralities can move in\ndifferent directions and be separated. In addition, we also proposed a space\nseparation method by introducing a constant load, where counterclockwise and\nclockwise particles stay in different regions of the channel."
    },
    {
        "anchor": "Yield Stress Discontinuity in a Simple Glass: Large scale molecular dynamics simulations are performed to study the steady\nstate yielding dynamics of a well established simple glass. In contrast to the\nsupercooled state, where the shear stress, $\\sigma$, tends to zero at vanishing\nshear rate, $\\gammadot$, a stress plateau forms in the glass which extends over\nabout two decades in shear rate. This strongly suggests the existence of a\nfinite dynamic yield stress in the glass, $\\sigma^+ (T) \\equiv \\sigma(T;\n\\gammadot \\to 0) >0$. Furthermore, the temperature dependence of $\\sigma^+$\nsuggests a yield stress discontinuity at the glass transition in agreement with\nrecent theoretical predictions. We scrutinize and support this observation by\ntesting explicitly for the assumptions (affine flow, absence of flow induced\nordering) inherent in the theory. Also, a qualitative change of the flow curves\nenables us to bracket the glass transition temperature $T_c$ of the theory from\nabove and (for the first time in simulations) {\\it from below}. Furthermore,\nthe structural relaxation time in the steady state behaves quite similar to the\nsystem viscosity at all studied shear rates and temperatures.",
        "positive": "Breakdown of the Kratky-Porod Wormlike Chain Model for Semiflexible\n  Polymers in Two Dimensions: By large-scale Monte Carlo simulations of semiflexible polymers in $d=2$\ndimensions the applicability of the Kratky-Porod model is tested. This model is\nwidely used as \"standard model\" for describing conformations and force versus\nextension curves of stiff polymers. It is shown that semiflexible polymers in\n$d=2$ show a crossover from hard rods to self-avoiding walks, the intermediate\nGaussian regime (implied by the Kratky-Porod model) is completely absent. Hence\nthe latter can also describe force versus extension curves only if the contour\nlength is only a few times larger than the persistence length. Consequences for\nexperiments on biopolymers at interfaces are briefly discussed."
    },
    {
        "anchor": "Mean-Field Theory of Feshbach-Resonant Interactions in 85Rb Condensates: Recent Feshbach-resonance experiments with 85Rb Bose-Einstein condensates\nhave led to a host of unexplained results: dramatic losses of condensate atoms\nfor an across-resonance sweep of the magnetic field, a collapsing condensate\nwith a burst of atoms emanating from the remnant condensate, increased losses\nfor decreasing interaction times-- until short times are reached, and seemingly\ncoherent oscillations between remnant and burst atoms. Using a simple yet\nrealistic mean-field model, we find that rogue dissociation, molecular\ndissociation to noncondensate atom pairs, is strongly implicated as the\nphysical mechanism responsible for these observations.",
        "positive": "Charge symmetry broken complex coacervation: Liquid-liquid phase separation has emerged as one of the important paradigms\nin the chemical physics as well as biophysics of charged macromolecular\nsystems. We elucidate an equilibrium phase separation mechanism based on charge\nregulation, i.e., protonation-deprotonation equilibria controlled by pH, in an\nidealized macroion system which can serve as a proxy for simple coacervation.\nFirst, a low-density density-functional calculation reveals the dominance of\ntwo-particle configurations coupled by ion adsorption on neighboring macroions.\nThen a binary cell model, solved on the Debye-H\\\"uckel as well as the full\nnonlinear Poisson-Boltzmann level, unveils the charge-symmetry breaking as\ninducing the phase separation between low- and high-density phases as a\nfunction of pH. These results can be identified as a charge symmetry broken\ncomplex coacervation between chemically identical macroions."
    },
    {
        "anchor": "Designing enhanced entropy binding in single-chain nano particles: Single-chain nanoparticles (SCNP) are a new class of bio and soft-matter\npolymeric objects in which a fraction of the monomers are able to form\nequivalently intra- or inter-polymer bonds. Here we numerically show that a\nfully-entropic gas-liquid phase separation can take place in SCNP systems.\nControl over the discontinuous (first-order) change -- from a phase of\nindependent diluted (fully-bonded) polymers to a phase in which polymers\nentropically bind to each other to form a (fully-bonded) polymer network -- can\nbe achieved by a judicious design of the patterns of reactive monomers along\nthe polymer chain. Such a sensitivity arises from a delicate balance between\nthe distinct entropic contributions controlling the binding.",
        "positive": "A silicone-based slippery polymer coating with humidity-dependent\n  nanoscale topography: Hypothesis: Slippery Omniphobic Covalently Attached Liquids (SOCAL) have been\nproposed for making omnirepellent thin films of self-assembled dimethylsiloxane\npolymer brushes grafted from silica surfaces. Smooth and flat at very small\nscale, these fluid surfaces could exhibit a more complex multiscale structure\nthough showing very weak contact angle hysteresis (less than\n5{\\textdegree}).Experiment: In this work, coatings were deposited on glass\nsurfaces from an acidic dimethoxydimethylsilane solution under carefully\ncontrolled relative humidity. Ellipsometry mapping was used to analyze the\nsurface structuration with nanometric thickness sensitivity. The sliding\nproperties were determined using a drop shape analyzer with a tilting device,\nand chemical analyses of the coatings were performed using on-surface\ntechniques (XPS, ATR-FTIR spectroscopy).Findings: Coated materials possessed an\nunexpected surface structure with multiscale semispherical-like features, which\nsurprisingly, did not increase the contact angle hysteresis. A careful study of\nsome parameters of the coating process and the related evolution of the surface\nproperties allowed us to propose a new model of the chemical organization of\nthe polymer to support this remarkable liquid-like behavior. These structures\nare made of end-grafted strongly adsorbed Guiselin brushes with\nhumidity-dependent thickness: the higher the humidity, the thinner and the more\nslippery the coating."
    },
    {
        "anchor": "Molecular Modeling of Aquaporins and Artificial Transmembrane Channels:\n  a mini-review and perspective for plants: Aquaporins (AQPs) are a family of transmembrane channels that are found from\narchaea, eubacteria, and fungi kingdoms to plants and animals. These proteins\nplay a major role in water and small solutes transport across biological cell\nmembranes and maintain the osmotic balance of living cells. In this sense, many\nworks in recent years have been devoted to understanding their behavior,\nincluding in plants, where 5 major groups of AQPs have been identified, whose\nphysiological function details still have open questions waiting for an answer.\nIn this direction, we observed in the literature very few Molecular Modeling\nstudies focusing on plant AQPs. It creates a gap in the proper depiction of\nAQPs since Molecular Simulations allow us to get information that is usually\ninaccessible by experiments. Likewise, many efforts have been made to create\nartificial nanochannels with improved properties. It has the potential to help\nhumanity (and plants) to face water stress -- a current problem that will be\nworsened by Climate Change. In this short review, we will revisit and discuss\nimportant computational studies about plant aquaporins and artificial\ntransmembrane channels. With this, we aim to show how the Molecular Modeling\ncommunity can (and should) help to understand plants' AQPs properties and\nfunction and how we can create new nanotechnology-based artificial channels.",
        "positive": "Rheology of inelastic hard spheres at finite density and shear rate: Considering a granular fluid of inelastic smooth hard spheres we discuss the\nconditions delineating the rheological regimes comprising Newtonian,\nBagnoldian, shear thinning, and shear thickening behavior. Developing a kinetic\ntheory, valid at finite shear rates and densities around the glass transition\ndensity, we predict the viscosity and Bagnold coefficient at practically\nrelevant values of the control parameters. The determination of full flow\ncurves relating the shear stress $\\sigma$ to the shear rate $\\dot\\gamma$, and\npredictions of the yield stress complete our discussion of granular rheology\nderived from first principles."
    },
    {
        "anchor": "Theory of helicoids and skyrmions in confined cholesteric liquid\n  crystals: Cholesteric liquid crystals experience geometric frustration when they are\nconfined between surfaces with anchoring conditions that are incompatible with\nthe cholesteric twist. Because of this frustration, they develop complex\ntopological defect structures, which may be helicoids or skyrmions. We develop\na theory for these structures, which extends previous theoretical research by\nderiving exact solutions for helicoids with the assumption of constant azimuth,\ncalculating numerical solutions for helicoids and skyrmions with varying\nazimuth, and interpreting the results in terms of competition between terms in\nthe free energy.",
        "positive": "Fractional Hereditariness of Lipid Membranes: Instabilities and\n  Linearized Evolution: In this work lipid ordering phase changes arising in planar membrane bilayers\nis investigated both accounting for elas- ticity alone and for effective\nviscoelastic response of such assemblies. The mechanical response of such\nmembranes is studied by minimizing the Gibbs free energy which penalizes\nperturbations of the changes of areal stretch and their gradients only [1]. As\nmaterial instabilities arise whenever areal stretches characterizing\nhomogeneous configurations lie inside the spinoidal zone of the free energy\ndensity, bifurcations from such configurations are shown to occur as\noscillatory perturbations of the in-plane displacement. Experimental\nobservations [2] show a power-law in-plane viscous behavior of lipid structures\nallowing for an effective viscoelastic behavior of lipid membranes [3], which\nfalls in the framework of Fractional Hereditariness. A suitable generalization\nof the variational principle invoked for the elasticity is applied in this\ncase, and the corresponding Euler-Lagrange equation is found together with a\nset of bound- ary and initial conditions. Separation of variables allows for\nshowing how Fractional Hereditariness owes bifurcated modes with a larger\nnumber of spatial oscillations than the corresponding elastic analog. Indeed,\nthe available range of areal stresses for material instabilities is found to\nincrease with respect to the purely elastic case. Nevertheless, the time\nevolution of the perturbations solving the Euler-Lagrange equation above\nexhibits time-decay and the large number of spatial oscillation slowly relaxes,\nthereby keeping the features of a long-tail type time-response."
    },
    {
        "anchor": "Microscopic Mechanism of Shear Bands in Amorphous Solids: The fundamental instability responsible for the shear localization which\nresults in shear bands in amorphous solids remains unknown despite enormous\namount of research, both experimental and theoretical. As this is the main\nmechanism for the failure of metallic glasses, understanding the instability is\ninvaluable in finding how to stabilize such materials against the tendency to\nshear localize. In this Letter we explain the mechanism for shear localization\nunder shear, which is the appearance of highly correlated lines of Eshelby-like\nquadrupolar singularities which organize the non-affine plastic flow of the\namorphous solid into a shear band. We prove analytically that such highly\ncorrelated solutions in which $\\C N$ quadrupoles are aligned with equal\norientations are minimum energy states when the strain is high enough. The line\nlies at 45 degrees to the compressive stress.",
        "positive": "Mpemba-like effect protocol for granular gases of inelastic and rough\n  hard disks: We study the conditions under which a Mpemba-like effect emerges in granular\ngases of inelastic and rough hard disks driven by a class of thermostats\ncharacterized by the splitting of the noise intensity into translational and\nrotational counterparts. Thus, granular particles are affected by a stochastic\nforce and a stochastic torque, which inject translational and rotational\nenergy, respectively. We realize that a certain choice of a thermostat of this\nclass can be characterized just by the total intensity and the fraction of\nnoise transferred to the rotational degree of freedom with respect to the\ntranslational ones. Firstly, Mpemba effect is characterized by the appearance\nof a crossing between the temperature curves of the considered samples. Later,\nan overshoot of the temperature evolution with respect to the steady-state\nvalue is observed and the mechanism of Mpemba effect generation is changed. The\nelection of parameters allows to design plausible protocols based on these\nthermostats for generating the initial states to observe the Mpemba-like effect\nin experiments. In order to obtain explicit results, we use a well-founded\nMaxwellian approximation for the evolution dynamics and the steady-state\nquantities. Finally, theoretical results are compared with direct simulation\nMonte Carlo and molecular dynamics results, and a very good agreement is found."
    },
    {
        "anchor": "Ordering Nanoparticles with Polymer Brushes: Ordering nanoparticles into a desired super-structure is often crucial for\ntheir technological applications. We use molecular dynamics simulations to\nstudy the assembly of nanoparticles in a polymer brush randomly grafted to a\nplanar surface as the solvent evaporates. Initially, the nanoparticles are\ndispersed in a solvent that wets the polymer brush. After the solvent\nevaporates, the nanoparticles are either inside the brush or adsorbed at the\nsurface of the brush, depending on the strength of the nanoparticle-polymer\ninteraction. For strong nanoparticle-polymer interactions, a 2-dimensional\nordered array is only formed when the brush density is finely tuned to\naccommodate a single layer of nanoparticles. When the brush density is higher\nor lower than this optimal value, the distribution of nanoparticles shows large\nfluctuations in space and the packing order diminishes. For weak\nnanoparticle-polymer interactions, the nanoparticles order into a hexagonal\narray on top of the polymer brush as long as the grafting density is high\nenough to yield a dense brush. An interesting healing effect is observed for a\nlow-grafting-density polymer brush that can become more uniform in the presence\nof weakly adsorbed nanoparticles.",
        "positive": "Pairing-induced motion of source and inert particles driven by surface\n  tension: We experimentally and theoretically investigate systems with a pair of source\nand inert particles that interacts through the concentration field. The\nexperimental system comprises a camphor disk as the source particle and a metal\nwasher as the inert particle. Both are floated on a red aqueous solution at\nvarious concentrations, where the glycerol modifies the viscosity of the\naqueous phase. The particles form a pair owing to the attractive lateral\ncapillary force. As the camphor disk spreads surface-active molecules at the\naqueous surface, the camphor disk and metal washer move together, driven by the\nsurface tension gradient. The washer is situated in the front of the camphor\ndisk, keeping the distance constant during their motion, which we call a\npairing-induced motion. The pairing-induced motion exhibited a transition\nbetween circular and straight motions as the glycerol concentration in the\naqueous phase changed. Numerical calculations using a model that considers\nforces caused by the surface tension gradient and lateral capillary interaction\nreproduced the observed transition in the pairing-induced motion. Moreover,\nthis transition agrees with the result of the linear stability analysis on the\nreduced dynamical system obtained by the expansion with respect to the particle\nvelocity. Our results reveal that the effect of the particle velocity cannot be\noverlooked to describe the interaction through the concentration field."
    },
    {
        "anchor": "Experimental Investigation of an Incremental Contact Model for\n  Hyperelastic Solids Using In-Situ Optical Interferometric Technique: The hyperelastic materials would contribute to the intricacies of rough\nsurface contact, primarily due to the heightened nonlinearity caused by stress\nconcentration. In our previous research, an incremental contact model tailored\nfor hyperelastic materials is proposed and validated by finite element (FEM)\nsimulations. From an experimental perspective, this study employs an in-situ\noptical interferometric technique to precisely document the actual contact zone\nbetween hyperelastic solids and quartz glass. Simultaneously, the contact force\nis meticulously recorded in sync by a force sensor positioned beneath the\nhyperelastic samples. Comparing with the predictions of incremental contact\nmodel for hyperelastic materials, a significant agreement becomes evident,\nalmost in a range of nearly complete contact. Its significance extends to\npractical domains such as sealing mechanisms, leakage prevention, and\nstructural integrity, offering valuable insights for these applications.",
        "positive": "Order-disorder transition in active nematic: A lattice model study: We introduce a lattice model for active nematic composed of self-propelled\napolar particles,study its different ordering states in the density-temperature\nparameter space, and compare with the corresponding equilibrium model. The\nactive particles interact with their neighbours within the framework of the\nLebwohl-Lasher model, and move anisotropically along their orientation to an\nunoccupied nearest neighbour lattice site. An interplay of the activity,\nthermal fluctuations and density gives rise distinct states in the system. For\na fixed temperature, the active nematic shows a disordered isotropic state, a\nlocally ordered inhomogeneous mixed state, and bistability between the\ninhomogeneous mixed and a homogeneous globally ordered state in different\ndensity regime. In the low temperature regime, the isotropic to the\ninhomogeneous mixed state transition occurs with a jump in the order parameter\nat a density less than the corresponding equilibrium disorder-order transition\ndensity. Our analytical calculations justify the shift in the transition\ndensity and the jump in the order parameter. We construct the phase diagram of\nthe active nematic in the density-temperature plane."
    },
    {
        "anchor": "Topological modes bound to dislocations in mechanical metamaterials: Mechanical metamaterials are artificial structures with unusual properties,\nsuch as negative Poisson ratio, bistability or tunable vibrational properties,\nthat originate in the geometry of their unit cell. At the heart of such unusual\nbehaviour is often a soft mode: a motion that does not significantly stretch or\ncompress the links between constituent elements. When activated by motors or\nexternal fields, soft modes become the building blocks of robots and smart\nmaterials. Here, we demonstrate the existence of topological soft modes that\ncan be positioned at desired locations in a metamaterial while being robust\nagainst a wide range of structural deformations or changes in material\nparameters. These protected modes, localized at dislocations, are the\nmechanical analogue of topological states bound to defects in electronic\nsystems. We create physical realizations of the topological modes in prototypes\nof kagome lattices built out of rigid triangular plates. We show mathematically\nthat they originate from the interplay between two Berry phases: the Burgers\nvector of the dislocation and the topological polarization of the lattice. Our\nwork paves the way towards engineering topologically protected nano-mechanical\nstructures for molecular robotics or information storage and read-out.",
        "positive": "Many-particle mobility and diffusion tensors for objects in viscous\n  sheets: We derive a mobility tensor for many cylindrical objects embedded in a\nviscous sheet. This tensor guarantees a positive dissipation rate for any\nconfiguration of particles and forces, analogously to the Rotne-Prager-Yamakawa\ntensor for spherical particles in a three-dimensional viscous fluid. We test\nour result for a ring of radially driven particles, demonstrating the\npositive-definite property at all particle densities. The derived tensor can be\nutilized in Brownian Dynamics simulations with hydrodynamic interactions for\nsuch systems as proteins in biomembranes and inclusions in free-standing liquid\nfilms."
    },
    {
        "anchor": "Test of classical nucleation theory on deeply supercooled high-pressure\n  simulated silica: We test classical nucleation theory (CNT) in the case of simulations of\ndeeply supercooled, high density liquid silica, as modelled by the BKS\npotential. We find that at density $\\rho=4.38$~g/cm$^3$, spontaneous nucleation\nof crystalline stishovite occurs in conventional molecular dynamics simulations\nat temperature T=3000 K, and we evaluate the nucleation rate J directly at this\nT via \"brute force\" sampling of nucleation events. We then use parallel,\nconstrained Monte Carlo simulations to evaluate $\\Delta G(n)$, the free energy\nto form a crystalline embryo containing n silicon atoms, at T=3000, 3100, 3200\nand 3300 K. We find that the prediction of CNT for the n-dependence of $\\Delta\nG(n)$ fits reasonably well to the data at all T studied, and at 3300 K yields a\nchemical potential difference between liquid and stishovite that matches\nindependent calculation. We find that $n^*$, the size of the critical nucleus,\nis approximately 10 silicon atoms at T=3300 K. At 3000 K, $n^*$ decreases to\napproximately 3, and at such small sizes methodological challenges arise in the\nevaluation of $\\Delta G(n)$ when using standard techniques; indeed even the\nthermodynamic stability of the supercooled liquid comes into question under\nthese conditions. We therefore present a modified approach that permits an\nestimation of $\\Delta G(n)$ at 3000 K. Finally, we directly evaluate at T=3000\nK the kinetic prefactors in the CNT expression for J, and find physically\nreasonable values; e.g. the diffusion length that Si atoms must travel in order\nto move from the liquid to the crystal embryo is approximately 0.2 nm. We are\nthereby able to compare the results for J at 3000 K obtained both directly and\nbased on CNT, and find that they agree within an order of magnitude.",
        "positive": "Quantum phase transition of condensed bosons in optical lattices: In this paper we study the superfluid-Mott-insulator phase transition of\nultracold dilute gas of bosonic atoms in an optical lattice by means of Green\nfunction method and Bogliubov transformation as well. The superfluid-\nMott-insulator phase transition condition is determined by the energy-band\nstructure with an obvious interpretation of the transition mechanism. Moreover\nthe superfluid phase is explained explicitly from the energy spectrum derived\nin terms of Bogliubov approach."
    },
    {
        "anchor": "Hierarchical Jamming in Frictional Particle Assemblies: The postulate of the existence of a jamming phase diagram (Liu and Nagel,\nNature 396, 21 EP (1998aa)) provides a theoretical basis for the classification\nof a wide range of amorphous solids (colloidal, molecular and emulsion glasses,\ncolloidal and polymer gels, foams and granular matter) on the basis of whether\nthese materials are in the jammed or unjammed state. Whilst such simple\nclassification is appealing, it fails to capture that the criterion of rigidity\nof such amorphous solids may be defined with respect to a particular\ndeformation orientation or mode (i.e. shear, extrusion, consolidation). We\nconsider this problem via the consolidation of strong colloidal gels, and find\nthat the critical transitions during the consolidation of a strong colloidal\ngel (as indicated by maxima and minima in the relative normal stress\ndifference) correspond directly to directed, frictional and non-frictional\nrigidity percolation. These results indicate a hierarchy of directed, jammed\nstates during consolidation of such amorphous solids, and a direct link between\nparticle-scale interactions and macroscopic collective behaviour of these\nsystems driven far from equilibrium",
        "positive": "Rescaling invariance and anomalous energy transport in a small vertical\n  column of grains: It is well known that energy dissipation and finite size can deeply affect\nthe dynamics of granular matter, often making usual hydrodynamic approaches\nproblematic. Here we report on the experi-mental investigation of a small model\nsystem, made of ten beads constrained into a 1-d geometry by a narrow vertical\npipe and shaken at the base by a piston excited by a periodic wave. Recording\nthe beads motion with high frame rate camera allows to investigate in detail\nthe microscopic dynamics and test hydrodynamic and kinetic models. Varying the\nenergy we explore different regimes from fully fluidized to the edge of\ncondensation, observing good hydrodynamic behavior down to the edge of\nfluidization, despite the small system size. Density and temperature fields for\ndifferent system energies can be collapsed by suitable space and time\nrescaling, and the expected constitutive equation holds very well when the\nparticle diameter is considered. At the same time the balance between\ndissipated and fed energy is not well described by commonly adopted dependence,\ndue to the up-down symmetry breaking. Our observations, supported by the\nmeasured particle velocity distributions, show a different phenomenological\ntemperature dependence, which yields equation solutions in agreement with\nexperimental results."
    },
    {
        "anchor": "Formation of Non-uniform Double Helices for Elastic Rods under Torsion: The spontaneous formation of double helices for filaments under torsion is\ncommon and significant. For example, the research on the supercoiling of DNA is\nhelpful for understanding the replication and transcription of DNA. Similar\ndouble helices can appear in polymer chains, carbon nanotube yarns, cables,\ntelephone wires and so forth. We noticed that non-uniform double helices can be\nproduced due to the surface friction induced by the self-contact. Therefore an\nideal model was presented to investigate the formation of double helices for\nelastic rods under torque. A general equilibrium condition which is valid for\nboth the smooth surface and the rough surface situations is derived by using\nthe variational method. Based on this, by adding further constraints, the\nsmooth and rough surface situations are investigated in detail respectively.\nAdditionally, the model showed that the specific process of how to twist and\nslack the rod can determine the surface friction and hence influence the\nconfiguration of the double helix formed by rods with rough surfaces. Based on\nthis principle, a method of manufacturing double helices with designed\nconfigurations was proposed and demonstrated. Finally, experiments were\nperformed to verify the model and the results agreed well with the theory.",
        "positive": "The dynamics of thin vibrated granular layers: We describe a series of experiments and computer simulations on vibrated\ngranular media in a geometry chosen to eliminate gravitationally induced\nsettling. The system consists of a collection of identical spherical particles\non a horizontal plate vibrating vertically, with or without a confining lid.\nPreviously reported results are reviewed, including the observation of\nhomogeneous, disordered liquid-like states, an instability to a `collapse' of\nmotionless spheres on a perfect hexagonal lattice, and a fluctuating,\nhexagonally ordered state. In the presence of a confining lid we see a variety\nof solid phases at high densities and relatively high vibration amplitudes,\nseveral of which are reported for the first time in this article. The phase\nbehavior of the system is closely related to that observed in confined\nhard-sphere colloidal suspensions in equilibrium, but with modifications due to\nthe effects of the forcing and dissipation. We also review measurements of\nvelocity distributions, which range from Maxwellian to strongly non-Maxwellian\ndepending on the experimental parameter values. We describe measurements of\nspatial velocity correlations that show a clear dependence on the mechanism of\nenergy injection. We also report new measurements of the velocity\nautocorrelation function in the granular layer and show that increased\ninelasticity leads to enhanced particle self-diffusion."
    },
    {
        "anchor": "Toroidal Crystals: Crystalline assemblages of identical sub-units packed together and\nelastically bent in the form of a torus have been found in the past ten years\nin a variety of systems of surprisingly different nature, such as viral\ncapsids, self-assembled monolayers and carbon nanomaterials. In this Letter we\nanalyze the structural properties of toroidal crystals and we provide a unified\ndescription based on the elastic theory of defects in curved geometries. We\nfind ground states characterized by the presence of 5-fold disclinations on the\nexterior of the torus and 7-fold disclinations in the interior. The number of\nexcess disclinations is controlled primarily by the aspect ratio of the torus,\nsuggesting a novel mechanism for creating toroidal templates with precisely\ncontrolled valency via functionalization of the defect sites.",
        "positive": "Twirling and Whirling: Viscous Dynamics of Rotating Elastica: Motivated by diverse phenomena in cellular biophysics, including bacterial\nflagellar motion and DNA transcription and replication, we study the overdamped\nnonlinear dynamics of a rotationally forced filament with twist and bend\nelasticity. Competition between twist injection, twist diffusion, and writhing\ninstabilities is described by a novel pair of coupled PDEs for twist and bend\nevolution. Analytical and numerical methods elucidate the twist/bend coupling\nand reveal two dynamical regimes separated by a Hopf bifurcation: (i)\ndiffusion-dominated axial rotation, or twirling, and (ii) steady-state\ncrankshafting motion, or whirling. The consequences of these phenomena for\nself-propulsion are investigated, and experimental tests proposed."
    },
    {
        "anchor": "Cooperation and competition in the collective drive by motor proteins:\n  Mean active force, fluctuations, and self-load: We consider the dynamics of a bio-filament under the collective drive of\nmotor proteins. They are attached irreversibly to a substrate and undergo\nstochastic attachment-detachment with the filament to produce a directed force\non it. We establish the dependence of the mean directed force and force\ncorrelations on the parameters describing the individual motor proteins using\nanalytical theory and direct numerical simulations. The effective Langevin\ndescription for the filament motion gives mean-squared displacement, asymptotic\ndiffusion constant, and mobility leading to an effective temperature. Finally,\nwe show how competition between motor protein extensions generates a self-load,\ndescribable in terms of the effective temperature, affecting the filament\nmotion.",
        "positive": "Activity-induced Nonequilibrium Vaporization Leads to Reentrant Phase\n  Separation: Active Brownian particles (ABPs) with pure repulsion is an ideal model to\nunderstand the effect of nonequilibrium on collective behaviors. It has long\nbeen established that activity can create effective attractions leading to\nmotility-induced phase separation (MIPS), whose role is similar to that of\n(inverse) temperature in the simplest equilibrium system with attractive\ninter-particle interactions. Here, our theoretical analysis based on a kinetic\ntheory of MIPS shows that a new type of activity-induced nonequilibrium\nvaporization is able to hinder the formation of dense phase when activity is\nlarge enough. Such nonequilibrium vaporization along with the activity-induced\neffective attraction thus lead to a MIPS reentrance. Numerical simulations\nverify such nonequilibrium effect induced solely by activity on phase behaviors\nof ABPs, and further demonstrate the dependence of MIPS on activity and the\nstrength of inter-particle interaction predicted by our theoretical analysis.\nOur findings highlight the unique role played by the nonequilibrium nature of\nactivity on phase behaviors of active systems, which may inspire deep insights\ninto the essential difference between equilibrium and nonequilibrium systems."
    },
    {
        "anchor": "Generalized effective depletion potentials: We propose that the behavior of asymmetric binary fluid mixtures with a large\nclass of attractive or repulsive interparticle interactions can be understood\nby mapping onto effective non-additive hard-sphere models. The latter are best\nanalyzed in terms of their underlying depletion potentials which can be exactly\nscaled onto known additive ones. By tuning the non-additivity, a wide variety\nof attractive or repulsive generalized depletion potential shapes and\nassociated phase behavior can be ``engineered'', leading, for example, to two\nways to stabilize colloidal suspensions by adding smaller particles.",
        "positive": "Nematic liquid crystals on sinusoidal channels: the zigzag instability: Substrates which are chemically or topographically patterned induce a variety\nof liquid crystal textures. The response of the liquid crystal to competing\nsurface orientations, typical of patterned substrates, is determined by the\nanisotropy of the elastic constants and the interplay of the relevant lengths\nscales, such as the correlation length and the surface geometrical parameters.\nTransitions between different textures, usually with different symmetries, may\noccur under a wide range of conditions. We use the Landau-de Gennes free energy\nto investigate the texture of nematics in sinusoidal channels with parallel\nanchoring bounded by nematic-air interfaces that favour perpendicular\n(hometropic) anchoring. In micron size channels 5CB was observed to exhibit a\nnon-trivial texture characterized by a disclination line, within the channel,\nwhich is broken into a zigzag pattern. Our calculations reveal that when the\nelastic anisotropy of the nematic does not favour twist distortions the defect\nis a straight disclination line that runs along the channel, which breaks into\na zigzag pattern with a characteristic period, when the twist elastic constant\nbecomes sufficiently small when compared to the splay and bend constants. The\ntransition occurs through a twist instability that drives the defect line to\nrotate from its original position. The interplay between the energetically\nfavourable twist distortions that induce the defect rotation and the liquid\ncrystal anchoring at the surfaces leads to the zigzag pattern. We investigate\nin detail the dependence of the periodicity of the zigzag pattern on the\ngeometrical parameters of the sinusoidal channels, which in line with the\nexperimental results is found to be non-linear."
    },
    {
        "anchor": "Modelless X-Ray Scattering Study of a Silica Hydrosol Surface: The structure of the adsorbed layer of alkali ions on the surface of\ncolloidal silica solutions with a particle size of ~27 nm has been studied by\nreflectometry and diffuse scattering of synchrotron radiation with a photon\nenergy of about 71 keV. Electron density profiles in the direction\nperpendicular to the surface have been reconstructed from experimental data and\nspectra of the correlation function of heights in the surface plane have been\nobtained. The revealed deviation of the integral and frequency characteristics\nof the roughness spectra of the silica sol surface from predictions of the\ncapillary-wave theory is of a fundamental character. This deviation is due to\nthe contribution from roughnesses with low spatial frequencies and to the\ninterference of diffuse scattering from different layer interfaces of the\nsurface structure.",
        "positive": "Equilibrium properties of highly asymmetric star-polymer mixtures: We employ effective interaction potentials to study the equilibrium structure\nand phase behavior of highly asymmetric mixtures of star polymers. We consider\nin particular the influence of the addition of a component with a small number\nof arms and a small size on a concentrated solution of large stars with a high\nfunctionality. By employing liquid integral equation theories we examine the\nevolution of the correlation functions of the big stars upon addition of the\nsmall ones, finding a loss of structure that can be attributed to a weakening\nof the repulsions between the large stars due to the presence of the small\nones. We analyze this phenomenon be means of a generalized depletion mechanism\nwhich is supported by computer simulations. By applying thermodynamic\nperturbation theory we draw the phase diagram of the asymmetric mixture,\nfinding that the addition of small stars melts the crystal formed by the big\nones. A systematic comparison between the two- and effective one-component\ndescriptions of the mixture that corroborates the reliability of the\ngeneralized depletion picture is also carried out."
    },
    {
        "anchor": "Isogeometric Analysis of Elastic Sheets Exhibiting Combined Bending and\n  Stretching using Dynamic Relaxation: Shells are ubiquitous thin structures that can undergo large nonlinear\nelastic deformations while exhibiting combined modes of bending and stretching,\nand have profound modern applications. In this paper, we have proposed a new\nIsogeometric formulation, based on classical Koiter nonlinear shell theory, to\nstudy instability problems like wrinkling and buckling in thin shells. The use\nof NURBS-basis provides rotation-free, conforming, higher-order spatial\ncontinuity, such that curvatures and membrane strains can be computed directly\nfrom the interpolation of the position vectors of the control points. A pseudo,\ndissipative and discrete, dynamical system is constructed, and static\nequilibrium solutions are obtained by the method of dynamic relaxation (DR). A\nhigh-performance computing-based implementation of the DR is presented, and the\nproposed formulation is benchmarked against several existing numerical, and\nexperimental results. The advantages of this formulation, over traditional\nfinite element approaches, in assessing structural response of the shells are\npresented.",
        "positive": "Inequivalence of Statistical Ensembles in Single Molecule Measurements: We study the role of fluctuations in single molecule experimental\nmeasurements of force-extension curves. We use the Worm Like Chain (WLC) model\nto bring out the connection between the Helmholtz ensemble characterized by the\nFree Energy and the Gibbs ensemble characterized by the Free Energy . We\nconsider the rigid rod limit of the WLC model as an instructive special case to\nbring out the issue of ensemble inequivalence. We point out the need for taking\ninto account the free energy of transition when one goes from one ensemble to\nanother. We also comment on the ``phase transition'' noticed in an isometric\nsetup for semiflexible polymers and propose a realization of its thermodynamic\nlimit. We present general arguments which rule out non-monotonic\nforce-extension curves in some ensembles and note that these do not apply to\nthe isometric ensemble."
    },
    {
        "anchor": "On the role of Lifshitz invariants in liquid crystals: The interaction between an external action and the order parameter, via a\ndependence described by a so-called Lifshitz invariant, is very important to\ndetermine the final configuration of the liquid crystal cells. The external\naction can be an electric field applied to the bulk or the confinement due to\nfree surfaces or cell walls. The Lifshitz invariant includes the order\nparameter in the form of an elastic strain. This coupling between elastic\nstrains and fields, inserted in a Landau-Ginzburg formalism, is well known and\ngive rise to striction effects causing undulations in the director\nconfiguration. We want to discuss here the role of Lifshitz coupling terms,\nfollowing an approach similar to that introduced by Dzyaloshinskii for magnetic\nmaterials. Case studies on nematics in planar and cylindrical cells are also\nproposed.",
        "positive": "Memory Effects in Active Particles with Exponentially Correlated\n  Propulsion: The Ornstein--Uhlenbeck Particle (OUP) model imagines a microscopic swimmer\npropelled by an active force which is correlated with itself on a finite\ntime-scale. Here we investigate the influence of external potentials on an\nideal suspension of OUPs, in both one and two spatial dimensions, with\nparticular attention paid to the pressure exerted on \"confining walls\". We\nemploy a mathematical connection between the local density of OUPs and the\nstatistics of their propulsion force to demonstrate the existence of an\nequation of state in one dimension. In higher dimensions we show that active\nparticles generate a non-conservative force field in the surrounding medium. A\nsimplified far-from-equilibrium model is proposed to account for OUP behaviour\nin the vicinity of potentials. Building on this, we interpret simulations of\nOUPs in more complicated situations involving asymmetrical and spatially curved\npotentials, characterising the inhomogeneous local stresses which result in\nterms of competing active length-scales."
    },
    {
        "anchor": "Hydrodynamics of granular gases of inelastic and rough hard disks or\n  spheres. II. Stability analysis: Conditions for the stability under linear perturbations around the\nhomogeneous cooling state are studied for dilute granular gases of inelastic\nand rough hard disks or spheres with constant coefficients of normal ($\\alpha$)\nand tangential ($\\beta$) restitution. After a formally exact linear stability\nanalysis of the Navier--Stokes--Fourier hydrodynamic equations in terms of the\ntranslational ($d_t$) and rotational ($d_r$) degrees of freedom, the transport\ncoefficients derived in the companion paper [A. Meg\\'ias and A. Santos,\n\"Hydrodynamics of granular gases of inelastic and rough hard disks or spheres.\nI. Transport coefficients,\" Phys. Rev. E 104, 034901 (2021)] are employed.\nKnown results for hard spheres [V. Garz\\'o, A. Santos, and G. M. Kremer, Phys.\nRev. E 97, 052901 (2018)] are recovered by setting $d_t=d_r=3$, while novel\nresults for hard disks ($d_t=2$, $d_r=1$) are obtained. In the latter case, a\nhigh-inelasticity peculiar region in the $(\\alpha,\\beta)$ parameter space is\nfound, inside which the critical wave number associated with the longitudinal\nmodes diverges. Comparison with event-driven molecular dynamics simulations for\ndilute systems of hard disks at $\\alpha=0.2$ shows that this theoretical region\nof absolute instability may be an artifact of the extrapolation to high\ninelasticity of the approximations made in the derivation of the transport\ncoefficients, although it signals a shrinking of the conditions for stability.\nIn the case of moderate inelasticity ($\\alpha=0.7$), however, a good agreement\nbetween the theoretical predictions and the simulation results is found.",
        "positive": "Transfer of planar orders onto a sphere: formation and properties of\n  complex topological defects: General topological principles how to transfer the planar orders onto a\nsphere are considered. Formation of extended topological defects (ETDs), which\nhave a reconstructed inner structure surrounded by perfect initial order, is\ndiscussed. Topological charge of the ETD can be determined from the shape of a\ncharacteristic polygon bounding the defect. Relation between the total\ntopological charge of all defects in the spherical structure and the type of\ninitial planar order is found. It is also demonstrated that in the spherical\nhexagonal crystal a dislocation located in the ETD area is actually absorbed by\nit, because the order outside the defect doesn't display existence of\ndislocation in any way. For the case of singly connected spherical hexagonal\norder arising from mutual repulsion of N particles (N < 1000) only\ntriangulation of the order inside the ETD regions recovers the linear scars\nwhich represent a narrow parts of wider ETD areas."
    },
    {
        "anchor": "Exploration of Self-Propelling Droplets Using a Curiosity Driven Robotic\n  Assistant: We describe a chemical robotic assistant equipped with a curiosity algorithm\n(CA) that can efficiently explore the state a complex chemical system can\nexhibit. The CA-robot is designed to explore formulations in an open-ended way\nwith no explicit optimization target. By applying the CA-robot to the study of\nself-propelling multicomponent oil-in-water droplets, we are able to observe an\norder of magnitude more variety of droplet behaviours than possible with a\nrandom parameter search and given the same budget. We demonstrate that the\nCA-robot enabled the discovery of a sudden and highly specific response of\ndroplets to slight temperature changes. Six modes of self-propelled droplets\nmotion were identified and classified using a time-temperature phase diagram\nand probed using a variety of techniques including NMR. This work illustrates\nhow target free search can significantly increase the rate of unpredictable\nobservations leading to new discoveries with potential applications in\nformulation chemistry.",
        "positive": "Structure of nanoparticles embedded in micellar polycrystals: We investigate by scattering techniques the structure of water-based soft\ncomposite materials comprising a crystal made of Pluronic block-copolymer\nmicelles arranged in a face-centered cubic lattice and a small amount (at most\n2% by volume) of silica nanoparticles, of size comparable to that of the\nmicelles. The copolymer is thermosensitive: it is hydrophilic and fully\ndissolved in water at low temperature (T ~ 0{\\deg}C), and self-assembles into\nmicelles at room temperature, where the block-copolymer is amphiphilic. We use\ncontrast matching small-angle neuron scattering experiments to probe\nindependently the structure of the nanoparticles and that of the polymer. We\nfind that the nanoparticles do not perturb the crystalline order. In addition,\na structure peak is measured for the silica nanoparticles dispersed in the\npolycrystalline samples. This implies that the samples are spatially\nheterogeneous and comprise, without macroscopic phase separation, silica-poor\nand silica-rich regions. We show that the nanoparticle concentration in the\nsilica-rich regions is about tenfold the average concentration. These regions\nare grain boundaries between crystallites, where nanoparticles concentrate, as\nshown by static light scattering and by light microscopy imaging of the\nsamples. We show that the temperature rate at which the sample is prepared\nstrongly influence the segregation of the nanoparticles in the\ngrain-boundaries."
    },
    {
        "anchor": "A vehicle with a two-wheel steering system mobile in shallow dense\n  granular media: We design a vehicle with a steering system made of two independently\nrotatable wheels on the front. We quantify the effectiveness of the steering\nsystem in the mobility and maneuverability of the vehicle running in a box\ncontaining a layer ping-pong balls with a packing density 0.8, below the random\nclose packing value 0.84 in 2D. The steering system can reduce the resistance\nexerted by the jammed balls formed ahead of the fast-moving vehicle. Moreover,\nif only one of the two steering wheels rotates, the vehicle can turn into the\ndirection opposite to the rotating wheel. The steering system performs more\nefficiently if the wheels engage the ping-pong balls better by increasing the\ncontact area between the wheels and the balls. We advocate applying our design\nto machines moving in granular materials with a moderate packing density.",
        "positive": "Coherent acceleration of Bose-Einstein condensates: We present a theoretical analysis of the coherent acceleration of atomic\nBose-Einstein condensates. A first scheme relies on the 'conveyor belt'\nprovided by a frequency-chirped optical lattice. For potentials shallow enough\nthat the condensate is not fragmented, the acceleration can be interpreted in\nterms of sequential Bragg scattering, with the atomic sample undergoing\ntransitions to a succession of discrete momentum sidemodes. The narrow momentum\nwidth of these sidemodes offers the possibility to accelerate an ultracold\natomic sample such as e.g. a Bose-Einstein condensate without change in its\nmomentum distribution. This is in contrast to classical point particles, for\nwhich this kind of acceleration leads to a substantial heating of the sample. A\nsecond scheme is based on the idea of a synchronous particle accelerator\nconsisting of a spatial array of quadrupole traps. Pulsing the trapping\npotential creates a traveling trap that confines and accelerates the atomic\nsystem. We study this process using the concept of phase stability."
    },
    {
        "anchor": "Hydrodynamics of Diffusion in Lipid Membrane Simulations: By performing molecular dynamics simulations with up to 132 million\ncoarse-grained particles in half-micron sized boxes, we show that hydrodynamics\nquantitatively explains the finite-size effects on diffusion of lipids,\nproteins, and carbon nanotubes in membranes. The resulting Oseen correction\nallows us to extract infinite-system diffusion coefficients and membrane\nsurface viscosities from membrane simulations despite the logarithmic\ndivergence of apparent diffusivities with increasing box width. The\nhydrodynamic theory of diffusion applies also to membranes with asymmetric\nleaflets and embedded proteins, and to a complex plasma-membrane mimetic.",
        "positive": "Bioinspired magnetic active matter and the physical limits of\n  magnetotaxis: Magnetotactic bacteria (MTB) are endowed with an exquisite orientation\nmechanism allowing them to swim along the geomagnetic field lines [1-3]. This\nmechanism consists of a chain of bio-synthesized magnetic nano-crystals\n[1,4,5]. Although the physics behind the minimum size of this biological\ncompass is well understood [6], it is yet unclear what sets its maximum size\n[6-8]. Here, by using a macroscopic experiment inspired in these\nmicroorganisms, we show that larger magnetic moments will drive the collective\nbehavior of MTB into a phase where bacteria are unable to swim freely, in\ndetriment of their evolutive fitness [3,9]. Simple macroscopic experiments,\nnumerical simulations, and analytic estimates are used to explain the upper\nlimit for the size of the chain of nano-crystals in MTB. Our macroscopic\nbio-inspired experiment, and physical model provide new opportunities to\nexplore and understand the phases of magnetic active matter at all scales."
    },
    {
        "anchor": "Role of Motility and Nutrient Availability in Drying Patterns of Algal\n  Droplets: Sessile drying droplets in various bio-relevant systems, encompassing passive\nbio-colloids like DNA, proteins, and blood to active microbes, gain\nconsiderable attention due to intricate interplay among different convective\nflows, droplet pinning, mechanical stress, wettability, and the emergence of\ndistinctive patterns. Chlamydomonas reinhardtii, or chlamys, is a versatile\nalgal model employed in molecular biology research and spanning diverse\nbiotechnological realms. While chlamys are harnessed at single-cell and\npopulation levels, their exploration in the context of drying sessile droplets\nremains limited. This paper illuminates the multifaceted potential of chlamys,\ndelving into motility-nutrient interactions and their role in emergent\nmorphological patterns. The interplay of two competing stressors -- localized\nnutrient scarcity and mechanical stress during drying -- is investigated.\nIrrespective of these stressors, the global mechanical stress fails to induce\nany cracks during the drying process. Interestingly, the reverse ``coffee-ring\neffect\" is predominantly observed in the non-motile chlamys in the presence of\nlocal nutrients whereas the nutrient depletion prompts local stress in motile\nchlamys, culminating in cooperative aggregation and cluster formation.\nFurthermore, the quantitative image processing technique leverages textural\nstatistics to classify the patterns into four classes, motile+with nutrients,\nmotile+without nutrients, non-motile+with nutrients, and non-motile+without\nnutrients, with five distinct drying stages -- Droplet Deposition, Capillary\nFlow, Dynamic Droplet Phase, Aggregation Phase, and Dried Morphology.",
        "positive": "Lattice models and Monte Carlo methods for simulating DNA origami\n  self-assembly: The optimal design of DNA origami systems that assemble rapidly and robustly\nis hampered by the lack of a model for self-assembly that is sufficiently\ndetailed yet computationally tractable. Here, we propose a model for DNA\norigami that strikes a balance between these two criteria by representing these\nsystems on a lattice at the level of binding domains. The free energy of\nhybridization between individual binding domains is estimated with a\nnearest-neighbour model. Double helical segments are treated as rigid rods, but\nwe allow flexibility at points where the backbone of one of the strands is\ninterrupted, which provides a reasonably realistic representation of partially\nand fully assembled states. Particular attention is paid to the constraints\nimposed by the double helical twist, as they determine where strand crossovers\nbetween adjacent helices can occur. To improve the efficiency of sampling\nconfiguration space, we develop Monte Carlo methods for sampling scaffold\nconformations in near-assembled states, and we carry out simulations in the\ngrand canonical ensemble, enabling us to avoid considering states with unbound\nstaples. We demonstrate that our model can quickly sample assembled\nconfigurations of a small origami design previously studied with the oxDNA\nmodel, as well as a design with staples that span longer segments of the\nscaffold. The sampling ability of our method should allow for good statistics\nto be obtained when studying the assembly pathways, and is suited to\ninvestigating in particular the effects of design and assembly conditions on\nthese pathways and their resulting final assembled structures."
    },
    {
        "anchor": "Bulk and interfacial stresses in suspensions of soft and hard colloids: We explore the influence of particle softness and internal structure on both\nthe bulk and interfacial rheological properties of colloidal suspensions. We\nprobe bulk stresses by conventional rheology, by measuring the flow curves,\nshear stress vs strain rate, for suspensions of soft, deformable microgel\nparticles and suspensions of near hard-sphere-like silica particles. A similar\nbehavior is seen for both kind of particles in suspensions at concentrations up\nto the random close packing volume fraction, in agreement with recent\ntheoretical predictions for sub-micron colloids. Transient interfacial stresses\nare measured by analyzing the patterns formed by the interface between the\nsuspensions and their own solvent, due to a generalized Saffman-Taylor\nhydrodynamic instability. At odd with the bulk behavior, we find that microgels\nand hard particle suspensions exhibit vastly different interfacial stress\nproperties. We propose that this surprising behavior results mainly from the\ndifference in particle internal structure (polymeric network for microgels vs\ncompact solid for the silica particles), rather than softness alone.",
        "positive": "The race to the bottom: approaching the ideal glass?: Key to resolving the scientific challenge of the glass transition is to\nunderstand the origin of the massive increase in viscosity of liquids cooled\nbelow their melting temperature (avoiding crystallisation). A number of\ncompeting and often mutually exclusive theoretical approaches have been\nadvanced to describe this phenomenon. Some posit a bona fide thermodynamic\nphase to an \"ideal glass\", an amorphous state with exceptionally low entropy.\nOther approaches are built around the concept of the glass transition as a\nprimarily dynamic phenomenon. These fundamentally different interpretations\ngive equally good descriptions of the data available, so it is hard to\ndetermine which -- if any -- is correct. Recently however this situation has\nbegun to change. A consensus has emerged that one powerful means to resolve\nthis longstanding question is to approach the putative thermodynamic transition\nsufficiently closely, and a number of techniques have emerged to meet this\nchallenge. Here we review the results of some of these new techniques and\ndiscuss the implications for the existence -- or otherwise -- of the\nthermodynamic transition to an ideal glass."
    },
    {
        "anchor": "Geometric charges and nonlinear elasticity of soft metamaterials: Problems of flexible mechanical metamaterials, and highly deformable porous\nsolids in general, are rich and complex due to nonlinear mechanics and\nnontrivial geometrical effects. While numeric approaches are successful,\nanalytic tools and conceptual frameworks are largely lacking. Using an analogy\nwith electrostatics, and building on recent developments in a nonlinear\ngeometric formulation of elasticity, we develop a formalism that maps the\nelastic problem into that of nonlinear interaction of elastic charges. This\napproach offers an intuitive conceptual framework, qualitatively explaining the\nlinear response, the onset of mechanical instability and aspects of the\npost-instability state. Apart from intuition, the formalism also quantitatively\nreproduces full numeric simulations of several prototypical structures.\nPossible applications of the tools developed in this work for the study of\nordered and disordered porous mechanical metamaterials are discussed.",
        "positive": "Simulating grain shape effects and damage in granular media using\n  PeriDEM: We provide a numerical platform for the analysis of particle shape and\ntopology effect on the macroscopic behavior of granular media. We work within a\nDiscrete Element Method (DEM) framework and apply a peridynamic model for\ndeformable particles accounting for deformation and damage of individual\nparticles. To accommodate arbitrary particle shapes including nonconvex ones as\nwell as particle topology, an efficient method is developed to keep\nintra-particle peridynamic interaction within particle boundaries. Particle\ncontact with the rigid boundary wall is computed analytically to improve\naccuracy. To speed up simulations with particles of different shapes and sizes\nthe initial configuration is chosen using security disks containing different\nparticle shapes that are placed in a jammed state using an optimization-based\nmethod. The effect of particle shape and topology on settling and compaction of\nthe aggregate for deformable particles is analyzed."
    },
    {
        "anchor": "Smectic Order in Double-Twist Cylinders: I propose a double-twist texture with local smectic order, which may have\nbeen seen in recent experiments. As in the Renn-Lubensky TGB phase, the smectic\norder is broken only through a lattice of screw dislocations. A melted lattice\nof screw dislocations can produce a double-twist texture as can an unmelted\nlattice. In the latter case I show that geometry only allows for certain angles\nbetween smectic regions. I discuss the possibility of connecting these\ndouble-twist tubes together to form a smectic blue phase.",
        "positive": "Evidence for a disorder induced phase transition in the condensation of\n  4He in aerogels: We report on thermodynamic and optical measurements of the condensation\nprocess of $^4$He in two silica aerogels of same porosity 95%, but different\nmicrostructures resulting from different pH during synthesis. For a\nbase-catalyzed aerogel, the temperature dependence of the shape of adsorption\nisotherms and of the morphology of the condensation process show evidence of a\ndisorder induced transition,in agreement with recent theoretical predictions.\nThis transition is not observed for a neutral-catalyzed aerogel, which we\ninterpret as due to a larger disorder in this case."
    },
    {
        "anchor": "Creep and Fracture of a Protein Gel under Stress: Biomaterials such as protein or polysaccharide gels are known to behave\nqualitatively as soft solids and to rupture under an external load. Combining\noptical and ultrasonic imaging to shear rheology we show that the failure\nscenario of a protein gel is reminiscent of brittle solids: after a primary\ncreep regime characterized by a power-law behavior which exponent is fully\naccounted for by linear viscoelasticity, fractures nucleate and grow\nlogarithmically perpendicularly to shear, up to the sudden rupture of the gel.\nA single equation accounting for those two successive processes nicely captures\nthe full rheological response. The failure time follows a decreasing power law\nwith the applied shear stress, similar to the Basquin law of fatigue for\nsolids. These results are in excellent agreement with recent fiber-bundle\nmodels that include damage accumulation on elastic fibers and exemplify protein\ngels as model, brittle-like soft solids.",
        "positive": "Flow boundary conditions for chain-end adsorbing polymer blends: Using the phenol-terminated polycarbonate blend as an example, we demonstrate\nthat the hydrodynamic boundary conditions for a flow of an adsorbing polymer\nmelt are extremely sensitive to the structure of the epitaxial layer. Under\nshear, the adsorbed parts (chain ends) of the polymer melt move along the\nequipotential lines of the surface potential whereas the adsorbed additives\nserve as the surface defects. In response to the increase of the number of the\nadsorbed additives the surface layer becomes thinner and solidifies. This\nresults in a gradual transition from the slip to the no-slip boundary condition\nfor the melt flow, with a non-monotonic dependence of the slip length on the\nsurface concentration of the adsorbed ends."
    },
    {
        "anchor": "Large deformation electrohydrodynamics of an elastic capsule in DC\n  electric field: The dynamics of a spherical elastic capsule, containing a Newtonian fluid\nbounded by an elastic membrane and immersed in another Newtonian fluid, in a\nuniform DC electric field is investigated. Discontinuity of electrical\nproperties such as conductivities of the internal and external fluid media as\nwell as capacitance and conductance of the membrane lead to a net interfacial\nMaxwell stress which can cause the deformation of such an elastic capsule. We\ninvestigate this problem considering well established membrane laws for a thin\nelastic membrane, with fully resolved hydrodynamics in the Stokes flow limit\nand describe the electrostatics using the capacitor model. In the limit of\nsmall deformation, the analytical theory predicts the dynamics fairly\nsatisfactorily. Large deformations at high capillary number though necessitate\na numerical approach (Boundary element method in the present case) to solve\nthis highly non-linear problem. Akin to vesicles, at intermediate times, highly\nnonlinear biconcave shapes along with squaring and hexagon like shapes are\nobserved when the outer medium is more conducting. The study identifies the\nessentiality of parameters such as high membrane capacitance, low membrane\nconductance, low hydrodynamic time scales and high capillary number for\nobservation of these shape transitions. The transition is due to large\ncompressive Maxwell stress at the poles at intermediate times. Thus such shape\ntransition can be seen in spherical globules admitting electrical capacitance,\npossibly, irrespective of the nature of the interfacial restoring force.",
        "positive": "The Geometry of Slow Structural Fluctuations in a Supercooled Binary\n  Alloy: The liquid structure of a glass-forming binary alloy is studied using\nmolecular dynamics simulations. The analysis combines common neighbour analysis\nwith the geometrical approach of Frank and Kasper to establish that the\nsupercooled liquid contains extended clusters characterised by the same short\nrange order as the crystal. Fluctuations in these clusters exhibit strong\ncorrelations with fluctuations in the inherent structure energy. The steep\nincrease in the heat capacity on cooling is, thus, directly coupled to the\ngrowing fluctuations of the Frank-Kasper clusters. The relaxation of particles\nin the clusters dominates the slow tail of the self-intermediate scattering\nfunction."
    },
    {
        "anchor": "Structure of benzothiadiazine at zwitterionic phospholipid cell\n  membranes: The use of drugs derived from benzothiadiazine, which is a bicyclic\nheterocyclic benzene derivative, has become a widespread treatment for diseases\nsuch as hypertension (treated with diuretics such as bendroflumethiazide or\nchlorothiazide), low blood sugar (treated with non-diuretic diazoxide) or the\nhuman immunodeficiency virus, among others. In this work we have investigated\nthe interactions of benzothiadiazine with the basic components of cell\nmembranes and solvents such as phospholipids, cholesterol, ions and water. The\nanalysis of the mutual microscopic interactions is of central importance to\nelucidate the local structure of benzothiadiazine as well as the mechanisms\nresponsible for the access of benzothiadiazine to the interior of the cell. We\nhave performed molecular dynamics simulations of benzothiadiazine embedded in\nthree different model zwitterionic bilayer membranes made by\ndimyristoilphosphatidylcholine, dioleoylphosphatidylcholine, 1,2-\ndioleoyl-sn-glycero-3-phosphoserine and cholesterol inside aqueous\nsodium-chloride solution in order to systematically examine microscopic\ninteractions of benzothiadiazine with the cell membrane at liquid-crystalline\nphase conditions. From data obtained through radial distribution functions,\nhydrogen-bonding lengths and potentials of mean force based on reversible work\ncalculations, we have observed that benzothiadiazine has a strong affinity to\nstay at the cell membrane interface although it can be fully solvated by water\nin short periods of time. Furthermore, benzothiadiazine is able to bind lipids\nand cholesterol chains by means of single and double hydrogen-bonds of\ndifferent characteristic lengths.",
        "positive": "Memory in cyclically crumpled sheets: We investigate the crumpling of a sheet as it is repeatedly crushed onto\nitself by rolling it into a cylinder and twisting it axially while allowing the\nend-to-end length to evolve freely. As deduced from its plastic deformations,\nthe sheet creases and collapses into structures which repeat and sharpen over\nhundreds of cycles to a remarkable degree before forming new configurations.\nThe observed metastablilty increases with applied cycles leading to recurrent\nstructures over a significant range of loading, but reconfigurations can\ncontinue to occur for large enough loading as the creases develop tears. The\nevolution of the sheet structure as measured by the mean curvature and the\ntotal crease length is found to increase logarithmically with cycle number with\na rate which increases with degree of compression. We explain the overall\nextent of creasing using flat folding models, and show the logarithmic growth\nas being a consequence of individual creases becoming sharper with number of\nfolding cycles, and due to the bifurcation in the curvature field leading to\nthe formation of new creases and folding pathways. Thus, we show that\nelastoplastic sheets can follow complex folding pathways to form convergent\nstructures after a sufficiently large number of training cycles provided\nmaterial fatigue remains unimportant."
    },
    {
        "anchor": "Soliton dynamics in a solid lubricant during sliding friction: Recent highly idealized model studies of lubricated nanofriction for two\ncrystalline sliding surfaces with an interposed thin solid crystalline\nlubricant layer showed that the overall relative velocity of the lubricant\n$v_{\\rm lub} / v_{\\rm slider}$ depends only on the ratio of the lattice\nspacings, and retains a strictly constant value even when system parameters are\nvaried within a wide range. This peculiar \"quantized\" dynamical locking was\nunderstood as due to the sliding-induced motion of misfit dislocations, or\nsoliton structures. So far, the practical relevance of this concept to\nrealistic sliding three dimensional crystals has not been demonstrated. In this\nwork, by means of classical molecular dynamics simulations and theoretical\nconsiderations, we realize a realistic three-dimensional\ncrystal-lubricant-crystal geometry. Results show that the flux of lubricant\nparticles associated to the advancing soliton lines gives rise here too to a\nquantized velocity ratio. Moreover, depending on the interface lattice spacing\nmismatch, both forward and backward quantized motion of the lubricant is\npredicted. The persistence under realistic conditions of the dynamically pinned\nstate and quantized sliding is further investigated by varying sliding speed,\ntemperature, load, and lubricant film thickness. The possibilities of\nexperimental observation of quantized sliding are also discussed.",
        "positive": "Resonant and antiresonant bouncing droplets: When placed onto a vibrating liquid bath, a droplet may adopt a permanent\nbouncing behavior, depending on both the forcing frequency and the forcing\namplitude. The relationship between the droplet deformations and the bouncing\nmechanism is studied experimentally and theoretically through an asymmetric and\ndissipative bouncing spring model. Antiresonance effects are evidenced.\nExperiments and theoretical predictions show that both resonance at specific\nfrequencies and antiresonance at Rayleigh frequencies play crucial roles in the\nbouncing mechanism. In particular, we show that they can be exploited for\ndroplet size selection."
    },
    {
        "anchor": "Energetic Instability Unjams Sand and Suspension: Jamming is a phenomenon occurring in systems as diverse as traffic, colloidal\nsuspensions and granular materials. A theory on the reversible elastic\ndeformation of jammed states is presented. First, an explicit granular\nstress-strain relation is derived that captures many relevant features of sand,\nincluding especially the Coulomb yield surface and a third-order jamming\ntransition. Then this approach is generalized, and employed to consider jammed\nmagneto- and electro-rheological fluids, again producing results that compare\nwell to experiments and simulations.",
        "positive": "Thermodynamic Modeling of Fluid Polyamorphism in Hydrogen at Extreme\n  Conditions: Fluid polyamorphism, the existence of multiple amorphous fluid states in a\nsingle-component system, has been observed or predicted in a variety of\nsubstances. A remarkable example of this phenomenon is the fluid-fluid phase\ntransition in high-pressure hydrogen between insulating and conducting\nhigh-density fluids. This transition is induced by the reversible\ndimerization/dissociation of the molecular and atomistic states of hydrogen. In\nthis work, we present the first attempt to thermodynamically model the\nfluid-fluid phase transition in hydrogen at extreme conditions. Our predictions\nfor the phase coexistence and the reaction equilibrium of the two alternative\nforms of fluid hydrogen are based on experimental data and supported by the\nresults of simulations. {Remarkably, we find that the law of corresponding\nstates can be utilized to construct a unified equation of state combining the\navailable computational results for different models of hydrogen and the\nexperimental data."
    },
    {
        "anchor": "Pseudo-Casimir interactions and surface anchoring duality in bookshelf\n  geometry of smectic-A liquid crystals: We analyze the transverse intersubstrate pseudo-Casimir force, arising as a\nresult of thermal fluctuations of the liquid crystalline layers of a smectic-A\nfilm confined between two planar substrates in a bookshelf geometry, in which\nthe equidistant smectic layers are placed perpendicular to the bounding\nsurfaces. We discuss the variation of the interaction force as a function of\nthe intersubstrate separation in the presence of surface anchoring to the\nsubstrates, showing that the force induced by confined fluctuations is\nattractive and depends on the penetration length as well as the layer spacing.\nThe strongest effect occurs for tightly confined fluctuations, in which the\nsurface anchoring energy is set to infinity, where the force per area scales\nlinearly with the thermal energy and inversely with the fourth power of the\nintersubstrate separation. By reducing the strength of the surface anchoring\nenergy, the force first becomes weaker in magnitude but then increases in\nmagnitude as the surface anchoring strength is further reduced down to zero, in\nwhich case the force tends to that obtained in the limit of strong anchoring.",
        "positive": "Effect of small particles on the near-wall dynamics of a large particle\n  in a highly bidisperse colloidal solution: We consider the hydrodynamic effect of small particles on the dynamics of a\nmuch larger particle moving normal to a planar wall in a highly bidisperse\ndilute colloidal suspension of spheres. The gap $h_0$ between the large\nparticle and the wall is assumed to be comparable to the diameter $2a$ of the\nsmaller particles so there is a length-scale separation between the gap width\n$h_0$ and the radius of the large particle $b<<h_0$. We use this length-scale\nseparation to develop a new lubrication theory which takes into account the\npresence of the smaller particles in the space between the larger particle and\nthe wall. The hydrodynamic effect of the small particles on the motion of the\nlarge particle is characterized by the short time (or high frequency)\nresistance coefficient. We find that for small particle-wall separations $h_0$,\nthe resistance coefficient tends to the asymptotic value corresponding to the\nlarge particle moving in a clear suspending fluid. For $h_0<<a$, the resistance\ncoefficient approaches the lubrication value corresponding to a particle moving\nin a fluid with the effective viscosity given by the Einstein formula."
    },
    {
        "anchor": "High pressure dynamics of hydrated protein in bio-protective trehalose\n  environment: We present a pressure dependence study of the dynamics of lysozyme protein\npowder immersed in deuterated $\\alpha$,$\\alpha$-trehalose environment via\nquasi-elastic neutron scattering (QENS). The goal is to assess the\nbaro-protective benefits of trehalose on bio-molecules by comparing the\nfindings with those of a trehalose-free reference study. While the mean-square\ndisplacement of the trehalose-free protein (hydrated to $d_{D_2O}\\simeq$40 w\\%)\nas a whole, is reduced by increasing pressure, the actual observable relaxation\ndynamics in the pico-(ps) to nano-seconds (ns) time range remains largely\nunaffected by pressure - up to the maximum investigated pressure of 2.78(2)\nKbar. Our observation is independent of whether or not the protein is mixed\nwith the deuterated sugar. This suggests that the hydrated protein's\nconformational states at atmospheric pressure remain unaltered by hydrostatic\npressures, below 2.78 Kbar. We also found the QENS response to be totally\nrecoverable after ambient pressure conditions are restored. Circular dichroism\nand neutron diffraction measurements confirm that the protein structural\nintegrity is conserved and remains intact, after pressure is released. We\nobserve however a clear narrowing of the quasi-elastic neutron (QENS) response\nas the temperature is decreased from 290 K to 230 K in both cases, which we\nparametrize using the Kohlrausch-Williams-Watts (KWW) stretched exponential\nmodel. Only the fraction of protons that are immobile on the accessible time\nwindow of the instrument, referred to as the elastic incoherent structure\nfactor or (EISF) is observably sensitive to pressure, increasing only\nmarginally but systematically with increasing pressure.",
        "positive": "Activity-controlled Annealing of Colloidal Monolayers: Molecular motors are essential to the living, they generate additional\nfluctuations that boost transport and assist assembly. Self-propelled colloids,\nthat consume energy to move, hold similar potential for the man-made assembly\nof microparticles. Yet, experiments showing their use as a powerhouse in\nmaterials science lack. Our work explores the design of man-made materials\ncontrolled by fluctuations, arising from the internal forces generated by\nactive colloids. Here we show a massive acceleration of the annealing of a\nmonolayer of passive beads by moderate addition of self-propelled\nmicroparticles. We rationalize our observations with a model of collisions that\ndrive active fluctuations to overcome kinetic barriers and activate the\nannealing. The experiment is quantitatively compared with Brownian dynamic\nsimulations that further unveil a dynamical transition in the mechanism of\nannealing. Active dopants travel uniformly in the system or co-localize at the\ngrain boundaries as a result of the persistence of their motion. Our findings\nuncover the potential of man-made materials controlled by internal activity and\nlay the groundwork for the rise of materials science beyond equilibrium."
    },
    {
        "anchor": "Close packing density of polydisperse hard spheres: The most efficient way to pack equally sized spheres isotropically in 3D is\nknown as the random close packed state, which provides a starting point for\nmany approximations in physics and engineering. However, the particle size\ndistribution of a real granular material is never monodisperse. Here we present\na simple but accurate approximation for the random close packing density of\nhard spheres of any size distribution, based upon a mapping onto a\none-dimensional problem. To test this theory we performed extensive simulations\nfor mixtures of elastic spheres with hydrodynamic friction. The simulations\nshow a general (but weak) dependence of the final (essentially hard sphere)\npacking density on fluid viscosity and on particle size, but this can be\neliminated by choosing a specific relation between mass and particle size,\nmaking the random close packed volume fraction well-defined. Our theory agrees\nwell with the simulations for bidisperse, tridisperse and log-normal\ndistributions, and correctly reproduces the exact limits for large size ratios.",
        "positive": "A New Mechanism of Model Membrane Fusion Determined from Monte Carlo\n  Simulation: We have carried out extensive Monte Carlo simulations of the fusion of tense\napposed bilayers formed by amphiphilic molecules within the framework of a\ncoarse grained lattice model. The fusion pathway differs from the usual stalk\nmechanism. Stalks do form between the apposed bilayers, but rather than expand\nradially to form an axial-symmetric hemifusion diaphragm of the trans leaves of\nboth bilayers, they promote in their vicinity the nucleation of small holes in\nthe bilayers. Two subsequent paths are observed: (i) The stalk encircles a hole\nin one bilayer creating a diaphragm comprised of both leaves of the other\nintact bilayer, and which ruptures to complete the fusion pore. (ii) Before the\nstalk can encircle a hole in one bilayer, a second hole forms in the other\nbilayer, and the stalk aligns and encircles them both to complete the fusion\npore. Both pathways give rise to mixing between the cis and trans leaves of the\nbilayer and allow for transient leakage."
    },
    {
        "anchor": "Extremal fluctuations driving the relaxation in glassy energy landscapes: Cooperative events requiring anomalously large fluctuations are a defining\ncharacteristic for the onset of glassy relaxation across many materials. The\nimportance of such intermittent events has been noted in systems as diverse as\nsuperconductors, metallic glasses, gels, colloids, and granular piles. Here, we\nshow that prohibiting the attainment of new record-high energy fluctuations --\nby explicitly imposing a ``lid'' on the fluctuation spectrum -- impedes further\nrelaxation in the glassy phase. This lid allows us to directly measure the\nimpact of record events on the evolving system in extensive simulations of\naging in such vastly distinct glass formers as spin glasses and tapped granular\npiles. Interpreting our results in terms of a dynamics of records succeeds in\nexplaining the ubiquity of both, the logarithmic decay of the energy and the\nmemory effects encoded in the scaling of two-time correlation functions of\naging systems.",
        "positive": "Equilibrium Fluid-Crystal Interfacial Free Energy of Bcc-Crystallizing\n  Aqueous Suspensions of Polydisperse Charged Spheres: The interfacial free energy is a central quantity in crystallization from the\nmeta-stable melt. In suspensions of charged colloidal spheres, nucleation and\ngrowth kinetics can be accurately measured from optical experiments. In\nprevious work, from this data effective non-equilibrium values for the\ninterfacial free energy between the emerging bcc-nuclei and the adjacent melt\nin dependence on the chemical potential difference between melt phase and\ncrystal phase were derived using classical nucleation theory. A strictly linear\nincrease of the interfacial free energy was observed as a function of increased\nmeta-stability. Here, we further analyze this data for five aqueous suspensions\nof charged spheres and one binary mixture. We utilize a simple extrapolation\nscheme and interpret our findings in view of Turnbull's empirical rule. Our\nfirst estimates for the reduced interfacial free energy, $\\sigma_{0,bcc}$,\nbetween coexisting equilibrium uid and bcc-crystal phases are on the order of a\nfew $k_BT$. Their values are not correlated to any of the electrostatic\ninteraction parameters but rather show a systematic decrease with increasing\nsize polydispersity and a lower value for the mixture as compared to the pure\ncomponents. At the same time, $\\sigma_0$ also shows an approximately linear\ncorrelation to the entropy of freezing. The equilibrium interfacial free energy\nof strictly monodisperse charged spheres may therefore be still greater."
    },
    {
        "anchor": "Phase behavior of weakly polydisperse sticky hard spheres: Perturbation\n  theory for the Percus-Yevick solution: We study the effects of size polydispersity on the gas-liquid phase behaviour\nof mixtures of sticky hard spheres. To achieve this, the system of coupled\nquadratic equations for the contact values of the partial cavity functions of\nthe Percus-Yevick solution is solved within a perturbation expansion in the\npolydispersity, i.e. the normalized width of the size distribution. This allows\nus to make predictions for various thermodynamic quantities which can be tested\nagainst numerical simulations and experiments. In particular, we determine the\nleading-order effects of size polydispersity on the cloud curve delimiting the\nregion of two-phase coexistence and on the associated shadow curve; we also\nstudy the extent of size fractionation between the coexisting phases. Different\nchoices for the size-dependence of the adhesion strengths are examined\ncarefully; the Asakura-Oosawa model of a mixture of polydisperse colloids and\nsmall polymers is studied as a specific example.",
        "positive": "Crystallinity characterization of white matter in the human brain: White matter microstructure underpins cognition and function in the human\nbrain through the facilitation of neuronal communication, and the non-invasive\ncharacterization of this structure remains a research frontier in the\nneuroscience community. Efforts to assess white matter microstructure, however,\nare hampered by the sheer amount of information needed for characterization.\nCurrent techniques within neuroimaging deal with this problem by representing\nwhite matter features with single scalars that are often not easy to interpret.\nHere, we address these issues by introducing tools from materials science for\nthe characterization of white matter microstructure. We investigate structure\non a mesoscopic scale by analyzing its homogeneity and determining which\nregions of the brain are structurally homogeneous, or \"crystalline\" in the\ncontext of materials science. We find that crystallinity provides novel\ninformation and varies across the brain along interpretable lines of anatomical\ndifference, with highest homogeneity in regions adjacent to the corpus\ncallosum. Furthermore, crystallinity is highly reliable, and yet also varies\nbetween individuals, making it a potentially useful biomarker to examine\nindividual differences in white matter along various dimensions. We also\nparcellate white matter into \"crystal grains,\" or contiguous sets of voxels of\nhigh structural similarity, and find overlap with other white matter\nparcellations. Finally, we characterize the shapes of local white matter\nsignatures through another tool from materials science - bond-orientational\norder parameters - and locate fiber crossings and fascicles with this new\ntechnique. Our results provide new means of assessing white matter\nmicrostructure on multiple length scales, and open new avenues of future\ninquiry. We hope that this work fosters future productive dialogue between the\nfields of soft matter and neuroscience."
    },
    {
        "anchor": "Interaction-driven effects on two-component Bose-Einstein condensates: We investigate the role of the interparticle-interaction strength in the\ndistribution of two species of atoms inside a condensate. We focus upon the\nstudy of systems for which the minima of the trapping potentials for the\nspecies are displaced from each other by a distance that is small compared to\nthe size of the total condensate. We show that in a small range of the\ninterparticle-interaction strength the distribution of species undergoes\ndramatic changes, and exhibits a variety of different features. We demonstrate\nthat this behavior can be easily understood in terms of the Thomas-Fermi\napproximation. This effect may be useful in experimentally determining the\nvalues of the scattering lengths.",
        "positive": "Deformation and break-up of viscoelastic droplets in confined shear flow: The deformation and break-up of Newtonian/viscoelastic droplets are studied\nin confined shear flow. Our numerical approach is based on a combination of\nLattice-Boltzmann models (LBM) and finite difference schemes, the former used\nto model two immiscible fluids with variable viscous ratio, and the latter used\nto model the polymer dynamics. The kinetics of the polymers is introduced using\nconstitutive equations for viscoelastic fluids with finitely extensible\nnon-linear elastic dumbbells with Peterlin's closure (FENE-P). We quantify the\ndroplet response by changing the polymer relaxation time $\\tau_P$, the maximum\nextensibility $L$ of the polymers, and the degree of confinement, i.e. the\nratio of the droplet diameter to gap spacing. In unconfined shear flow, the\neffects of droplet viscoelasticity on the critical Capillary number\n$\\mbox{Ca}_{\\mbox{\\tiny{cr}}}$ for break-up are moderate in all cases studied.\nHowever, in confined conditions a different behaviour is observed: the critical\nCapillary number of a viscoelastic droplet increases or decreases, depending on\nthe maximum elongation of the polymers, the latter affecting the extensional\nviscosity of the polymeric solution. Force balance is monitored in the\nnumerical simulations to validate the physical picture."
    },
    {
        "anchor": "Impurity effects in thermal regelation: When a particle is placed in a material with a lower bulk melting\ntemperature, intermolecular forces can lead to the existence of a premelted\nliquid film of the lower melting temperature material. Despite the system being\nbelow the melting temperatures of both solids, the liquid film is a consequence\nof thermodynamic equilibrium, controlled by intermolecular, ionic and other\ninteractions. An imposed temperature gradient drives the translation of the\nparticle by a process of melting and refreezing known as thermal regelation. We\ncalculate the rate of regelation of spherical particles surrounded by premelted\nfilms that contain ionic impurities. The impurities enhance the rate of motion\nthereby influencing the dynamics of single particles and distributions of\nparticles, which we describe in addition to the consequences in natural and\ntechnological settings.",
        "positive": "Dynamics of Janus motors with microscopically reversible kinetics: Janus motors with chemically active and inactive hemispheres can operate only\nunder nonequilibrium conditions where detailed balance is broken by fluxes of\nchemical species that establish a nonequilibrium state. A microscopic model for\nreversible reactive collisions on a Janus motor surface is constructed and\nshown to satisfy detailed balance. The model is used to study Janus particle\nreactive dynamics in systems at equilibrium where generalized chemical rate\nlaws that include time-dependent rate coefficients with power-law behavior are\nshown to describe reaction rates. While maintaining reversible reactions on the\nJanus catalytic hemisphere, the system is then driven into a nonequilibrium\nsteady state by fluxes of chemical species that control the chemical affinity.\nThe statistical properties of the self-propelled Janus motor in this\nnonequilibrium steady state are investigated and compared with predictions of a\nfluctuating thermodynamics theory. The model has utility beyond the examples\npresented here, since it allows one to explore various aspects of\nnonequilibrium fluctuations in systems with self-diffusiophoretic motors from a\nmicroscopic perspective."
    },
    {
        "anchor": "A mechanistic model for the growth of cylindrical debris particles in\n  the presence of adhesion: The wear volume is known to keep increasing during frictional processes, and\nArchard notably proposed a model to describe the probability of wear particle\nformation upon asperity collision in a two-body contact configuration. While\nthis model is largely adopted in the investigations of wear, the presence of\nwear debris trapped between the surfaces changes the system into a three-body\ncontact configuration already since the early stages of the process. In such a\nconfiguration, a significant amount of wear is produced at the interface\nbetween the trapped debris and the sliding bodies. Here, relying on analytical\nmodels, we develop a framework that describes crack growth in a three-body\nconfiguration at the particle-surface interface. We then show that crack growth\nis favoured within the sliding surfaces, instead of within the debris particle,\nand test such result by means of numerical simulations with a phase-field\napproach to fracture. This leads to an increase in the wear volume and to\ndebris particle accretion, rather than its break down. The effects of adhesion,\ncoefficient of friction, and ratio of the applied global tangential and normal\nforces are also investigated.",
        "positive": "The excluded volume of two-dimensional convex bodies: Shape\n  reconstruction and non-uniqueness: In the Onsager model of one-component hard-particle systems, the entire phase\nbehaviour is dictated by a function of relative orientation, which represents\nthe amount of space excluded to one particle by another at this relative\norientation. We term this function the excluded volume function. Within the\ncontext of two-dimensional convex bodies, we investigate this excluded volume\nfunction for one-component systems addressing two related questions. Firstly,\ngiven a body can we find the excluded volume function?, Secondly, can we\nreconstruct a body from its excluded volume function? The former is readily\nanswered via an explicit Fourier series representation, in terms of the support\nfunction. However we show the latter question is ill-posed in the sense that\nsolutions are not unique for a large class of bodies. This degeneracy is well\ncharacterised however, with two bodies admitting the same excluded volume\nfunction if and only if the Fourier coefficients of their support functions\ndiffer only in phase. Despite the non-uniqueness issue, we then propose and\nanalyse a method for reconstructing a convex body given its excluded volume\nfunction, by means of a discretisation procedure where convex bodies are\napproximated by zonotopes with a fixed number of sides. It is shown that the\nalgorithm will always asymptotically produce a best $L^2$ approximation of the\ntrial function, within the space of excluded volume functions of centrally\nsymmetric bodies. In particular, if a solution exists, it can be found. Results\nfrom a numerical implementation are presented, showing that with only desktop\ncomputing power, good approximations to solutions can be readily found."
    },
    {
        "anchor": "An infinitely long flexible polymer chain in between two parallel plates: We consider a fully directed self-avoiding walk model on a cubic lattice to\nmimic the conformations of an infinitely long confined flexible polymer chain;\nand the confinement condition is achieved by two parallel athermal plates. The\nconfined polymer system is under good solvent condition and we revisit this\nproblem to solve the real polymer's model for any length of chain and also for\nany separation in between the plates. The equilibrium statistics of the\nconfined polymer chain is derived using an analytical calculations based on the\ngenerating function technique. The force of the confinement, the surface\ntension and the monomer density profile of confined chain is obtained. We\npropose that a method of calculations is suitable to understand thermodynamics\nof an arbitrary length confined polymer chain.",
        "positive": "Structural transformations in porous glasses under mechanical loading.\n  II. Compression: The role of porous structure and glass density in response to compressive\ndeformation of amorphous materials is investigated via molecular dynamics\nsimulations. The disordered, porous structures were prepared by quenching a\nhigh-temperature binary mixture below the glass transition into the phase\ncoexistence region. With decreasing average glass density, the pore morphology\nin quiescent samples varies from a random distribution of compact voids to a\nporous network embedded in a continuous glass phase. We find that during\ncompressive loading at constant volume, the porous structure is linearly\ntransformed in the elastic regime and the elastic modulus follows a power-law\nincrease as a function of the average glass density. Upon further compression,\npores deform significantly and coalesce into large voids leading to formation\nof domains with nearly homogeneous glass phase, which provides an enhanced\nresistance to deformation at high strain."
    },
    {
        "anchor": "Phase-separation during sedimentation of dilute bacterial suspensions: Numerous natural systems depend on the sedimentation of passive particles in\npresence of swimming microorganisms. Here, we investigate the dynamics of the\nsedimentation of spherical colloids at various E. coli concentration within the\ndilute regime. Results show the appearance of two sedimentation fronts, a\nspherical particle front and the bacteria front. We find that the bacteria\nfront behave diffusive at short times, whereas at long times decays linearly.\nThe sedimentation speed of passive particles decays at a constant speed and\ndecreases as bacteria concentration ($\\phi_b$) is increased. As $\\phi_b$ is\nincreased further, the sedimentation speed becomes independent of $\\phi_b$. The\ntimescales of the bacteria front is associated with the particle settling\nspeeds. Remarkably, all experiments collapse onto a single master line by using\nthe bacteria front timescale. A phenomenological model is proposed that\ncaptures the sedimentation of passive particles in active fluids.",
        "positive": "Cooperative crosslink (un)binding in slowly driven bundles of\n  semiflexible filaments: Combining simulations and theory I study the interplay between bundle elastic\ndegrees of freedom and crosslink binding propensity. By slowly driving bundles\ninto a deformed configuration, and depending on the mechanical stiffness of the\ncrosslinking agent, the binding affinity is shown to display a sudden and\ndiscontinuous drop. This indicates a cooperative unbinding process that\ninvolves the crossing of a free-energy barrier. Choosing the proper\ncrosslinker, therefore, not only allows to change the composite elastic\nproperties of the bundle, but also the relevant time-scales, which can be tuned\nfrom the single-crosslink binding rate to the much longer escape time over the\nfree-energy barrier."
    },
    {
        "anchor": "Local orientations of fluctuating fluid interfaces: Thermal fluctuations cause the local normal vectors of fluid interfaces to\ndeviate from the vertical direction defined by the flat mean interface\nposition. This leads to a nonzero mean value of the corresponding polar tilt\nangle which renders a characterization of the thermal state of an interface.\nBased on the concept of an effective interface Hamiltonian we determine the\nvariances of the local interface position and of its lateral derivatives. This\nleads to the probability distribution functions for the metric of the interface\nand for the tilt angle which allows us to calculate its mean value and its mean\nsquare deviation. We compare the temperature dependences of these quantities as\npredicted by the simple capillary wave model, by an improved phenomenological\nmodel, and by the microscopic effective interface Hamiltonian derived from\ndensity functional theory. The mean tilt angle discriminates clearly between\nthese theoretical approaches and emphasizes the importance of the variation of\nthe surface tension at small wave lengths. Also the tilt angle two-point\ncorrelation function is determined which renders an additional structural\ncharacterization of interfacial fluctuations. Various experimental accesses to\nmeasure the local orientational fluctuations are discussed.",
        "positive": "A kinetic model of a polyelectrolyte gel undergoing phase separation: In this study we use non-equilibrium thermodynamics to systematically derive\na phase-field model of a polyelectrolyte gel coupled to a hydrodynamic model\nfor a salt solution surrounding the gel. The governing equations for the gel\naccount for the free energy of the internal interfaces which form upon phase\nseparation, the nonlinear elasticity of the polyelectrolyte network, and\nmulti-component diffusive transport following a Stefan--Maxwell approach. The\ntime-dependent model describes the evolution of the gel across multiple time\nand spatial scales and so is able to capture the large-scale solvent flux and\nthe emergence of long-time pattern formation in the system. We explore the\nmodel for the case of a constrained gel undergoing uni-axial deformations.\nNumerical simulations show that rapid changes in the gel volume occur once the\nvolume phase transition sets in, as well as the triggering of spinodal\ndecomposition that leads to strong inhomogeneities in the lateral stresses,\npotentially leading to experimentally visible patterns."
    },
    {
        "anchor": "Kinetics of motile solitons in fluid nematics: Solitary waves, dubbed \"solitons\", are special types of waves that propagate\nfor an infinite distance under ideal conditions. These waves are ubiquitously\nfound in nature such as typhoon or neuron signals. Yet, their artificial\ngeneration and the control of their propagation remain outstanding challenges\nin materials science owing to an insufficient understanding of the experimental\nconditions and theoretical aspects. Herein, a generic strategy for forming\nparticle-like solitons and controlling their kinetics in nematic fluid media is\nreported. The key to the realisation of the generation of solitons and the\ncontrol of their kinetics is the coupling between the fluid elasticity and the\nbackground flow flux, as evidenced by experimental observations and theoretical\napproaches. The findings of this study enable the exploration of solitons in a\nwide range of materials and have technological ramifications for the lossless\ntransport of energy or structures.",
        "positive": "Statistical mechanics of two-dimensional turbulence: The statistical mechanical description of two-dimensional inviscid fluid\nturbulence is reconsidered. Using this description, we make predictions about\nturbulent flow in a rapidly rotating laboratory annulus. Measurements on the\ncontinuously forced, weakly dissipative flow reveal coherent vortices in a mean\nzonal flow. Statistical mechanics has two crucial requirements for equilibrium:\nstatistical independence of macro-cells (subsystems) and additivity of\ninvariants of macro-cells. We use additivity to select the appropriate Casimir\ninvariants from the infinite set available in vortex dynamics, and we do this\nin such a way that the exchange of micro-cells within a macro-cell does not\nalter an invariant of a macro-cell. A novel feature of the present study is our\nchoice of macro-cells, which are continuous phase space curves based on mean\nvalues of the streamfunction. Quantities such as energy and enstrophy can be\ndefined on each curve, and these lead to a local canonical distribution that is\nalso defined on each curve. Our approach leads to the prediction that on a mean\nstreamfunction curve there should be a linear relation between the\nensemble-averaged potential vorticity and the time-averaged streamfunction, and\nour laboratory data are in good accord with this prediction. Further, the\napproach predicts that although the probability distribution function for\npotential vorticity in the entire system is non-Gaussian, the distribution\nfunction of micro-cells should be Gaussian on the macro-cells, i.e., for curves\ndefined by mean values of the streamfunction. This prediction is also supported\nby the data. While the statistical mechanics approach used was motivated by and\napplied to experiments on turbulence in a rotating annulus, the approach is\nquite general and is applicable to a large class of Hamiltonian systems."
    },
    {
        "anchor": "Reference Interaction Site Model and Optimized Perturbation theories of\n  colloidal dumbbells with increasing anisotropy: We investigate thermodynamic properties of anisotropic colloidal dumbbells in\nthe frameworks provided by the Reference Interaction Site Model (RISM) theory\nand an Optimized Perturbation Theory (OPT), this latter based on a fourth-order\nhigh-temperature perturbative expansion of the free energy, recently\ngeneralized to molecular fluids. Our model is constituted by two identical\ntangent hard spheres surrounded by square-well attractions with same widths and\nprogressively different depths. Gas-liquid coexistence curves are obtained by\npredicting pressures, free energies, and chemical potentials. In comparison\nwith previous simulation results, RISM and OPT agree in reproducing the\nprogressive reduction of the gas-liquid phase separation as the anisotropy of\nthe interaction potential becomes more pronounced; in particular, the RISM\ntheory provides reasonable predictions for all coexistence curves, bar the\nstrong anisotropy regime, whereas OPT performs generally less well. Both\ntheories predict a linear dependence of the critical temperature on the\ninteraction strength, reproducing in this way the mean-field behavior observed\nin simulations; the critical density~--~that drastically drops as the\nanisotropy increases~--~turns to be less accurate. Our results appear as a\nrobust benchmark for further theoretical studies, in support to the simulation\napproach, of self-assembly in model colloidal systems.",
        "positive": "Self-learning mechanical circuits: Computation, mechanics and materials merge in biological systems, which can\ncontinually self-optimize through internal adaptivity across length scales,\nfrom cytoplasm and biofilms to animal herds. Recent interest in such\nmaterial-based computation uses the principles of energy minimization, inertia\nand dissipation to solve optimization problems. Although specific computations\ncan be performed using dynamical systems, current implementations of material\ncomputation lack the ability to self-learn. In particular, the inverse problem\nof designing self-learning mechanical systems which can use physical\ncomputations to continuously self-optimize remains poorly understood. Here we\nintroduce the concept of self-learning mechanical circuits, capable of taking\nmechanical inputs from changing environments and constantly updating their\ninternal state in response, thus representing an entirely mechanical\ninformation processing unit. Our circuits are composed of a new mechanical\nconstruct: an adaptive directed spring (ADS), which changes its stiffness in a\ndirectional manner, enabling neural network-like computations. We provide both\na theoretical foundation and experimental realization of these elastic learning\nunits and demonstrate their ability to autonomously uncover patterns hidden in\nenvironmental inputs. By implementing computations in an embodied physical\nmanner, the system directly interfaces with its environment, thus broadening\nthe scope of its learning behavior. Our results pave the way towards the\nconstruction of energy-harvesting, adaptive materials which can autonomously\nand continuously sense and self-optimize to gain function in different\nenvironments."
    },
    {
        "anchor": "Boson Peak decouples from elasticity in glasses with low connectivity: We perform molecular-dynamics simulations of the vibrational and the\nelasto-plastic properties of polymeric glasses and crystals and corresponding\natomic systems. We evidence that the elastic scaling of the density of states\nin the low-frequency boson peak (BP) region is different in crystals and\nglasses. Also, we see that the BP of the polymeric glass is nearly coincident\nwith the one of the atomic glasses, thus revealing that the former -\ndifferently from elasticity - is controlled by non-bonding interactions only.\nOur results suggest that the interpretation of the BP in terms of macroscopic\nelasticity, discussed in highly connected systems, does not hold for systems\nwith low connectivity.",
        "positive": "Quantitatively consistent, scale-spanning model for same-material\n  tribocharging: By rigorously accounting for mesoscale spatial correlations in donor/acceptor\nsurface properties, we develop a scale-spanning model for same-material\ntribocharging. We find that mesoscale correlations affect not only the\nmagnitude of charge transfer but also the fluctuations-suppressing otherwise\noverwhelming charge-transfer variability that is not observed experimentally.\nWe furthermore propose a generic theoretical mechanism by which the mesoscale\nfeatures might emerge, which is qualitatively consistent with other proposals\nin the literature."
    },
    {
        "anchor": "Non-linear Poisson-Boltzmann Theory for Swollen Clays: The non-linear Poisson-Boltzmann equation for a circular, uniformly charged\nplatelet, confined together with co- and counter-ions to a cylindrical cell, is\nsolved semi-analytically by transforming it into an integral equation and\nsolving the latter iteratively. This method proves efficient, robust, and can\nbe readily generalized to other problems based on cell models, treated within\nnon-linear Poisson-like theory. The solution to the PB equation is computed\nover a wide range of physical conditions, and the resulting osmotic equation of\nstate is shown to be in fair agreement with recent experimental data for\nLaponite clay suspensions, in the concentrated gel phase.",
        "positive": "Early-stage aggregation in three-dimensional charged granular gas: Neutral grains made of the same dielectric material can attain considerable\ncharges due to collisions and generate long-range interactions. We perform\nmolecular dynamic simulations in three dimensions for a dilute, freely-cooling\ngranular gas of viscoelastic particles that exchange charges during collisions.\nAs compared to the case of clustering of viscoelastic particles solely due to\ndissipation, we find that the electrostatic interactions due to collisional\ncharging alter the characteristic size, morphology and growth rate of the\nclusters. The average cluster size grows with time as a power law, whose\nexponent is relatively larger in the charged gas than the neutral case. The\ngrowth of the average cluster size is found to be independent of the ratio of\ncharacteristic Coulomb to thermal energy, or equivalently, of the typical\nBjerrum length. However, this ratio alters the crossover time of the growth.\nBoth simulations and mean-field calculations based on the Smoluchowski's\nequation suggest that a suppression of particle diffusion due to the\nelectrostatic interactions helps in the aggregation process."
    },
    {
        "anchor": "Mean field description of aging linear response in athermal amorphous\n  solids: We study the linear response to strain in a mean field elastoplastic model\nfor athermal amorphous solids, incorporating the power-law mechanical noise\nspectrum arising from plastic events. In the \"jammed\" regime of the model,\nwhere the plastic activity exhibits a non-trivial slow relaxation referred to\nas aging, we find that the stress relaxes incompletely to an age-dependent\nplateau, on a timescale which grows with material age. We determine the scaling\nbehaviour of this aging linear response analytically, finding that key scaling\nexponents are universal and independent of the noise exponent $\\mu$. For\n$\\mu>1$, we find simple aging, where the stress relaxation timescale scales\nlinearly with the age $t_{\\rm w}$ of the material. At $\\mu=1$, which\ncorresponds to interactions mediated by the physical elastic propagator, we\nfind instead a $t_{\\rm w}^{1/2}$ scaling arising from the stretched exponential\ndecay of the plastic activity. We compare these predictions with measurements\nof the linear response in computer simulations of a model jammed system of\nrepulsive soft athermal particles, during its slow dissipative relaxation\ntowards mechanical equilibrium, and find good agreement with the theory.",
        "positive": "Surface Elastic Constants of a Soft Solid: Solid interfaces have intrinsic elasticity. However, in most experiments,\nthis is obscured by bulk stresses. Through microscopic observations of the\ncontact-line geometry of a partially wetting droplet on an anisotropically\nstretched substrate, we measure two surface-elastic constants that quantify the\nlinear dependence of the surface stress of a soft polymer gel on its strain.\nWith these two parameters, one can predict surface stresses for general\ndeformations of the material in the linear-elastic limit."
    },
    {
        "anchor": "Do the repulsive and attractive pair forces play separate roles for the\n  physics of liquids?: According to standard liquid-state theory repulsive and attractive pair\nforces play distinct roles for the physics of liquids. This paradigm is put\ninto perspective here by demonstrating a continuous series of pair potentials\nthat have virtually the same structure and dynamics, although only some of them\nhave attractive forces of significance. Our findings reflect the fact that the\nmotion of a given particle is determined by the total force on it, whereas the\nquantity usually discussed in liquid-state theory is the individual pair force.",
        "positive": "On the Behavior of Hexane on Graphite at Near-Monolayer Densities: We present the results of molecular dynamics (MD) studies of hexane\nphysisorbed onto graphite for eight coverages in the range $0.875 \\le \\rho \\le\n1.05$ (in units of monolayers). At low temperatures the adsorbate molecules\nform a uniaxially incommensurate herringbone (UI-HB) solid. At high coverages\nthe solid consists of adsorbate molecules that are primarily rolled on their\nside perpen-dicular to the surface of the substrate. As the coverage is\ndecreased, the amount of molecular rolling diminishes until $\\rho$ = 0.933\nwhere it disappears (molecules become primarily parallel to the surface). If\nthe density is decreased enough, vacancies appear. As the temperature is\nincreased we observe a three-phase regime for $\\rho > 0.933$ (with an\norientationally ordered nematic mesophase), for lower coverages the system\nmelts directly to the disordered (and isotropic) liquid phase. The\nsolid-nematic transition temperature is very sensitive to coverage whereas the\nmelting temperature is quite insensitive to it, except for at low coverages\nwhere increased in-plane space and ultimately vacancies soften the solid phase\nand lower the melting temperature. Our results signal the importance of\nmolecular rolling and tilting (which result from an the competition between\nmolecule-molecule and molecule-substrate interactions) for the formation of the\nintermediate phase, while the insensitivity of the system's melting temperature\nto changing density is understood in terms of in-plane space occupation through\nrolling. Comparisons and contrasts with experimental results are discussed."
    },
    {
        "anchor": "Granular packing simulation protocols: tap, press and relax: Granular matter takes many paths to pack. Gentle compression, compaction or\nrepetitive tapping can happen in natural and industrial processes. The path\ninfluences the packing microstructure, and thus macroscale properties,\nparticularly for frictional grains. We perform discrete element modeling\nsimulations to construct packings of frictional spheres implementing a range of\nstress-controlled protocols with 3D periodic boundary conditions. A\nvolume-controlled over-compression method is compared to four stress-controlled\nmethods, including over-compression and release, gentle under-compression and\ncyclical compression and release. The packing volume fraction of each method\ndepends on the pressure, initial kinetic energy and protocol parameters. A\nnon-monotonic pressure dependence in the volume fraction, but not the\ncoordination number occurs when dilute particles initialized with a non-zero\nkinetic energy are compressed, but can be reduced with the inclusion of drag.\nThe fraction of frictional contacts correlates with the volume fraction\nminimum. Packings were cyclically compressed 1000 times. Response to\ncompression depends on pressure; low pressure packings have a constant volume\nfraction regime, while high pressure packings continue to get dense with number\nof cycles. The capability of stress-controlled, bulk-like particle simulations\nto capture different protocols is showcased, and the ability to pack at low\npressures demonstrates unexpected behavior.",
        "positive": "Supervised learning in physical networks: From machine learning to\n  learning machines: Materials and machines are often designed with particular goals in mind, so\nthat they exhibit desired responses to given forces or constraints. Here we\nexplore an alternative approach, namely physical coupled learning. In this\nparadigm, the system is not initially designed to accomplish a task, but\nphysically adapts to applied forces to develop the ability to perform the task.\nCrucially, we require coupled learning to be facilitated by physically\nplausible learning rules, meaning that learning requires only local responses\nand no explicit information about the desired functionality. We show that such\nlocal learning rules can be derived for any physical network, whether in\nequilibrium or in steady state, with specific focus on two particular systems,\nnamely disordered flow networks and elastic networks. By applying and adapting\nadvances of statistical learning theory to the physical world, we demonstrate\nthe plausibility of new classes of smart metamaterials capable of adapting to\nusers' needs in-situ."
    },
    {
        "anchor": "Solvent mediated interactions close to fluid-fluid phase separation:\n  microscopic treatment of bridging in a soft core fluid: Using density functional theory we calculate the density profiles of a binary\nsolvent adsorbed around a pair of big solute particles. All species interact\nvia repulsive Gaussian potentials. The solvent exhibits fluid-fluid phase\nseparation and for thermodynamic states near to coexistence the big particles\ncan be surrounded by a thick adsorbed `wetting' film of the coexisting solvent\nphase. On reducing the separation between the two big particles we find there\ncan be a `bridging' transition as the wetting films join to form a fluid\nbridge. The potential between the two big particles becomes long ranged and\nstrongly attractive in the bridged configuration. Within our mean-field\ntreatment the bridging transition results in a discontinuity in the solvent\nmediated force. We demonstrate that accounting for the phenomenon of bridging\nrequires the presence of a non-zero bridge function in the correlations between\nthe solute particles when our model fluid is described within a full mixture\ntheory based upon the Ornstein-Zernike equations.",
        "positive": "Thermal diode made by nematic liquid crystal: This work investigates how a thermal diode can be designed from a nematic\nliquid crystal confined inside a cylindrical capillary. In the case of\nhomeotropic anchoring, a defect structure called escaped radial disclination\narises. The asymmetry of such structure causes thermal rectification rates up\nto 3.5\\% at room temperature, comparable to thermal diodes made from carbon\nnanotubes. Sensitivity of the system with respect the heat power supply, the\ngeometry of the capillary tube and the molecular anchoring angle is also\ndiscussed."
    },
    {
        "anchor": "Strain Fields in Repulsive Colloidal Crystals: The concept of a local linear elastic strain field is commonly used in the\nmetallurgical research community to approximate the collective effect of atomic\ndisplacements around crystalline defects. Here we show that the elastic strain\nfield approximation is a useful tool in colloidal systems. For colloidal\ncrystals with repulsive particle interaction potentials, given similar\nmechanical properties, sharper potentials lead to: 1) free energies of\ndeformation dominated by entropy, 2) lower variance in strain field\nfluctuations, 3) increased tension-compression asymmetry near dislocation core\nregions, and 4) smaller windows of applicability of the linear elastic\napproximation. We show that the window of linear behavior for entropic\ncolloidal crystals is broadened for pressures at which the inter-particle\nseparation sufficiently exceeds the range of steep repulsive interactions.",
        "positive": "Frictionless nanohighways on crystalline surfaces: The understanding of friction at nano-scales, ruled by the regular\narrangement of atoms, is surprisingly incomplete. Here we provide a unified\nunderstanding by studying the interlocking potential energy of two infinite\ncontacting surfaces with arbitrary lattice symmetries, and extending it to\nfinite contacts. We categorize, based purely on geometrical features, all\npossible contacts into three different types: a structurally lubric contact\nwhere the monolayer can move isotropically without friction, a corrugated and\nstrongly interlocked contact, and a newly discovered directionally structurally\nlubric contact where the layer can move frictionlessly along one specific\ndirection and retains finite friction along all other directions. This novel\ncategory is energetically stable against rotational perturbations and provides\nextreme friction anisotropy. The finite-size analysis shows that our\ncategorization applies to a wide range of technologically relevant materials in\ncontact, from adsorbates on crystal surfaces to layered two-dimensional\nmaterials and colloidal monolayers."
    },
    {
        "anchor": "Spontaneous soliton formation and modulational instability in\n  Bose-Einstein condensates: The dynamics of an elongated attractive Bose-Einstein condensate in an\naxisymmetric harmonic trap is studied. It is shown that density fringes caused\nby self-interference of the condensate order parameter seed modulational\ninstability. The latter has novel features in contradistinction to the usual\nhomogeneous case known from nonlinear fiber optics. Several open questions in\nthe interpretation of the recent creation of the first matter-wave bright\nsoliton train [Strecker {\\it et al.} Nature {\\bf 417} 150 (2002)] are\naddressed. It is shown that primary transverse collapse, followed by secondary\ncollapse induced by soliton--soliton interactions, produce bursts of hot atoms\nat different time scales.",
        "positive": "Collective ratchet transport generated by particle crowding under\n  asymmetric sawtooth-shaped static potential: In this study, we describe the ratchet transport of particles under static\nasymmetric potential with periodicity. Ratchet transport has garnered\nconsiderable attention due to its potential for developing smart transport\ntechniques on a micrometer scale. In previous studies, either particle\nself-propulsion or time varying potential was introduced to realize\nunidirectional transport. Without utilizing these two factors, we\nexperimentally demonstrate ratchet transport through particle interactions\nduring crowding. Such ratchet transport induced by particle interaction has not\nbeen experimentally demonstrated thus far, although some theoretical studies\nhad suggested that particle crowding enhances ratchet transport. In addition,\nwe constructed a model for such transport in which the potential varies\ndepending on the particle density, which agrees well with our experimental\nresults. This study can accelerate the development of transport techniques on a\nmicrometer scale."
    },
    {
        "anchor": "Flow induced by a sphere settling in an aging yield-stress fluid: We have studied the flow induced by a macroscopic spherical particle settling\nin a Laponite suspension that exhibits a yield-stress, thixotropy and\nshear-thinning. We show that the fluid thixotropy (or aging) induces an\nincrease with time of both the apparent yield stress and shear-thinning\nproperties but also a breaking of the flow fore-aft symmetry predicted in\nHershel-Bulkley fluids (yield-stress, shear-thinning fluids with no\nthixotropy). We have also varied the stress exerted by the particles on the\nfluid by using particles of different densities. Although the stresses exerted\nby the particles are of the same order of magnitude, the velocity field\npresents utterly different features: whereas the flow around the lighter\nparticle shows a confinement similar to the one observed in shear-thinning\nfluids, the wake of the heavier particle is characterized by an upward motion\nof the fluid (\"negative wake\"), whatever the fluid's age. We compare the\nfeatures of this negative wake to the one observed in viscoelastic\nshear-thinning fluids (polymeric or micelle solutions). Although the flows\naround the two particles strongly differ, their settling behaviors display no\napparent difference which constitutes an intriguing result and evidences the\ncomplexity of the dependence of the drag factor on flow field.",
        "positive": "Velocity Correlations in an Active Nematic: The flow properties of a continuum model for an active nematic is studied and\ncompared with recent experiments on suspensions of microtubule bundles and\nmolecular motors. The velocity correlation length is found to be independent of\nthe strength of the activity while the characteristic velocity scale increases\nmonotonically as the activity is increased, both in agreement with the\nexperimental observations. We interpret our results in terms of the creation\nand annihilation dynamics of a gas of topological defects."
    },
    {
        "anchor": "Three and four current reversals versus temperature in correlation\n  ratchets with a simple sawtooh potential: Transport of Brownian particles on a simple sawtooth potential subjected to\nboth unbiased thermal and nonequilibrium symmetric three-level Markovian noise\nis considered. The new effects of three and four current reversals as a\nfunction of temperature are established in such correlation ratchets. The\nparameter space coordinates of the fixed points associated with these current\nreversals and the necessary and sufficient conditions for the existence of the\nnovel current reversals are found.",
        "positive": "Effect of hydrogen bond cooperativity on the behavior of water: Four scenarios have been proposed for the low--temperature phase behavior of\nliquid water, each predicting different thermodynamics. The physical mechanism\nwhich leads to each is debated. Moreover, it is still unclear which of the\nscenarios best describes water, as there is no definitive experimental test.\nHere we address both open issues within the framework of a microscopic cell\nmodel by performing a study combining mean field calculations and Monte Carlo\nsimulations. We show that a common physical mechanism underlies each of the\nfour scenarios, and that two key physical quantities determine which of the\nfour scenarios describes water: (i) the strength of the directional component\nof the hydrogen bond and (ii) the strength of the cooperative component of the\nhydrogen bond. The four scenarios may be mapped in the space of these two\nquantities. We argue that our conclusions are model-independent. Using\nestimates from experimental data for H bond properties the model predicts that\nthe low-temperature phase diagram of water exhibits a liquid--liquid critical\npoint at positive pressure."
    },
    {
        "anchor": "Metastability limit for the nucleation of NaCl crystals in confinement: We study the spontaneous nucleation and growth of sodium chloride crystals\ninduced by controlled evaporation in confined geometries (microcapillaries)\nspanning several orders of magnitude in volume. In all experiments, the\nnucleation happens reproducibly at a very high supersaturation S~1.6 and is\nindependent of the size, shape and surface properties of the microcapillary. We\nshow from classical nucleation theory that this is expected: S~1.6 corresponds\nto the point where nucleation first becomes observable on experimental time\nscales. A consequence of the high supersaturations reached at the onset of\nnucleation is the very rapid growth of a single skeletal (Hopper) crystal.\nExperiments on porous media reveal also the formation of Hopper crystals in the\nentrapped liquid pockets in the porous network and consequently underline the\nfact that sodium chloride can easily reach high supersaturations, in spite of\nwhat is commonly assumed for this salt.",
        "positive": "Self-assembly of DNA-functionalized colloids: Colloidal particles grafted with single-stranded DNA (ssDNA) chains can\nself-assemble into a number of different crystalline structures, where\nhybridization of the ssDNA chains creates links between colloids stabilizing\ntheir structure. Depending on the geometry and the size of the particles, the\ngrafting density of the ssDNA chains, and the length and choice of DNA\nsequences, a number of different crystalline structures can be fabricated.\nHowever, understanding how these factors contribute synergistically to the\nself-assembly process of DNA-functionalized nano- or micro-sized particles\nremains an intensive field of research. Moreover, the fabrication of long-range\nstructures due to kinetic bottlenecks in the self-assembly are additional\nchallenges. Here, we discuss the most recent advances from theory and\nexperiment with particular focus put on recent simulation studies."
    },
    {
        "anchor": "Microscopic theory of capillary pressure hysteresis based on pore-space\n  accessivity and radius-resolved saturation: Continuum models of porous media use macroscopic parameters and state\nvariables to capture essential features of pore-scale physics. We propose a\nmacroscopic property \"accessivity\" ($\\alpha$) to characterize the network\nconnectivity of different sized pores in a porous medium, and macroscopic state\ndescriptors \"radius-resolved saturations\" ($\\psi_w(F),\\psi_n(F)$) to\ncharacterize the distribution of fluid phases within. Small accessivity\n($\\alpha\\to0$) implies serial connections between different sized pores, while\nlarge accessivity ($\\alpha\\to1$) corresponds to more parallel arrangements, as\nthe classical capillary bundle model implicitly assumes. Based on these\nconcepts, we develop a statistical theory for quasistatic immiscible\ndrainage-imbibition in arbitrary cycles, and arrive at simple algebraic\nformulae for updating $\\psi_n(F)$ that naturally capture capillary pressure\nhysteresis, with $\\alpha$ controlling the amount of hysteresis. These concepts\nmay be used to interpret hysteretic data, upscale pore-scale observations, and\nformulate new constitutive laws by providing a simple conceptual framework for\nquantifying connectivity effects, and may have broader utility in continuum\nmodeling of transport, reactions, and phase transformations in porous media.",
        "positive": "Nonlinear and Linear Elastodynamics Transformation Cloaking: We formulate the problems of nonlinear and linear elastodynamics\ntransformation cloaking in a geometric framework. It is noted that a cloaking\ntransformation is neither a spatial nor a referential change of frame\n(coordinates); a cloaking transformation maps the boundary-value problem of an\nisotropic and homogeneous elastic body (virtual problem) to that of an\nanisotropic and inhomogeneous elastic body with a hole surrounded by a cloak\nthat is to be designed (physical problem). The virtual body has a desired\nmechanical response while the physical body is designed to mimic the same\nresponse outside the cloak using a cloaking transformation. We show that\nnonlinear elastodynamics transformation cloaking is not possible while\nnonlinear elastostatics cloaking may be possible for special deformations,\ne.g., radial deformations in a body with either a cylindrical or a spherical\ncavity. For linear elastodynamics, in line with the previous observations in\nthe literature, we show that the elastic constants in the cloak are not fully\nsymmetric; they do not possess the minor symmetries. We prove that\ntransformation cloaking is not possible regardless of the shape of the hole and\nthe cloak. We next show that linear elastodynamics transformation cloaking\ncannot be achieved for gradient elastic solids either; similar to classical\nlinear elasticity the balance of angular momentum is the obstruction to\ntransformation cloaking. We finally prove that transformation cloaking is not\npossible for linear elastic generalized Cosserat solids in 2D for any shape of\nthe hole and the cloak. Particularly, in 2D, transformation cloaking cannot be\nachieved in linear Cosserat elasticity. We also show that transformation\ncloaking for a spherical cavity covered by a spherical cloak is not possible in\nthe setting of linear elastic generalized Cosserat solids. We conjecture that\nthis result holds for a cavity of any shape."
    },
    {
        "anchor": "Particle dynamics and effective temperature of jammed granular matter in\n  a slowly sheared 3D Couette cell: We report experimental measurements of particle dynamics on slowly sheared\ngranular matter in a three-dimensional (3D) Couette cell. A closely-packed\nensemble of transparent spherical beads is confined by an external pressure and\nfilled with fluid to match both the density and refractive index of the beads.\nThis allows us to track tracer particles embedded in the system and obtain\nthree-dimensional trajectories as a function of time. We study the PDF of the\nvertical and radial displacements, finding Gaussian and exponential\ndistributions, respectively. For slow shear rates, the mean-square fluctuations\nin all three directions are found to be dependent only on the angular\ndisplacement of the Couette cell. Both the diffusivity and mobility of tracer\nparticles are proportional to the shear rate, giving rise to a constant\neffective temperature, characteristic of the jammed system.",
        "positive": "An O(N^2) Approximation for Hydrodynamic Interactions in Brownian\n  Dynamics Simulations: In the Ermak-McCammon algorithm for Brownian Dynamics, the hydrodynamic\ninteractions (HI) between N spherical particles are described by a 3N x 3N\ndiffusion tensor. This tensor has to be factorized at each timestep with a\nruntime of O(N^3), making the calculation of the correlated random\ndisplacements the bottleneck for many-particle simulations. Here we present a\nfaster algorithm for this step, which is based on a truncated expansion of the\nhydrodynamic multi-particle correlations as two-body contributions. The\ncomparison to the exact algorithm and to the Chebyshev approximation of Fixman\nverifies that for bead-spring polymers this approximation yields about 95% of\nthe hydrodynamic correlations at an improved runtime scaling of O(N^2) and a\nreduced memory footprint. The approximation is independent of the actual form\nof the hydrodynamic tensor and can be applied to arbitrary particle\nconfigurations. This now allows to include HI into large many-particle Brownian\ndynamics simulations, where until now the runtime scaling of the correlated\nrandom motion was prohibitive."
    },
    {
        "anchor": "Improving sequencing by tunneling with multiplexing and\n  cross-correlations: Sequencing by tunneling is a next-generation approach to read single-base\ninformation using electronic tunneling transverse to the single-stranded DNA\n(ssDNA) backbone while the latter is translocated through a narrow channel. The\noriginal idea considered a single pair of electrodes to read out the current\nand distinguish the bases [1, 2]. Here, we propose an improvement to the\noriginal sequencing by tunneling method, in which $N$ pairs of electrodes are\nbuilt in series along a synthetic nanochannel. While the ssDNA is forced\nthrough the channel using a longitudinal field it passes by each pair of\nelectrodes for long enough time to gather a minimum of $m$ tunneling current\nmeasurements, where $m$ is determined by the level of sequencing error desired.\nEach current time series for each nucleobase is then cross-correlated together,\nfrom which the DNA bases can be distinguished. We show using random sampling of\ndata from classical molecular dynamics, that indeed the sequencing error is\nsignificantly reduced as the number of pairs of electrodes, $N$, increases.\nCompared to the sequencing ability of a single pair of electrodes,\ncross-correlating $N$ pairs of electrodes is exponentially better due to the\napproximate log-normal nature of the tunneling current probability\ndistributions. We have also used the Fenton-Wilkinson approximation to\nanalytically describe the mean and variance of the cross-correlations that are\nused to distinguish the DNA bases. The method we suggest is particularly useful\nwhen the measurement bandwidth is limited, allowing a smaller electrode gap\nresidence time while still promising to consistently identify the DNA bases\ncorrectly.",
        "positive": "Non-uniform liquid--crystalline phases of parallel hard rod-shaped\n  particles: From ellipsoids to cylinders: In this article we consider systems of parallel hard {\\it superellipsoids},\nwhich can be viewed as a possible interpolation between ellipsoids of\nrevolution and cylinders. Superellipsoids are characterized by an aspect ratio\nand an exponent $\\alpha$ (shape parameter) which takes care of the geometry,\nwith $\\alpha=1$ corresponding to ellipsoids of revolution, while\n$\\alpha=\\infty$ is the limit of cylinders. It is well known that, while hard\nparallel cylinders exhibit nematic, smectic, and solid phases, hard parallel\nellipsoids do not stabilize the smectic phase, the nematic phase transforming\ndirectly into a solid as density is increased. We use computer simulation to\nfind evidence that for $\\alpha\\ge\\alpha_c$, where $\\alpha_c$ is a critical\nvalue which the simulations estimate to be in the interval 1.2--1.3, the\nsmectic phase is stabilized. This is surprisingly close to the ellipsoidal\ncase. In addition, we use a density-functional approach, based on the\nParsons--Lee approximation, to describe smectic and columnar ordering. In\ncombination with a free--volume theory for the crystalline phase, a theoretical\nphase diagram is predicted. While some qualitative features, such as the\nenhancement of smectic stability for increasing $\\alpha$, and the probable\nabsence of a stable columnar phase, are correct, the precise location of\ncoexistence densities are quantitatively incorrect."
    },
    {
        "anchor": "Molecular Dynamics Study of Orientational Cooperativity in Water: Recent experiments on liquid water show collective dipole orientation\nfluctuations dramatically slower then expected (with relaxation time $>$ 50 ns)\n[D. P. Shelton, Phys. Rev. B {\\bf 72}, 020201(R) (2005)]. Molecular dynamics\nsimulations of SPC/E water show large vortex-like structure of dipole field at\nambient conditions surviving over 300 ps [J. Higo at al. PNAS, {\\bf 98} 5961\n(2001)]. Both results disagree with previous results on water dipoles in\nsimilar conditions, for which autocorrelation times are a few ps. Motivated by\nthese recent results, we study the water dipole reorientation using molecular\ndynamics simulations in bulk SPC/E water for temperatures ranging from ambient\n300 K down to the deep supercooled region of the phase diagram at 210 K. First,\nwe calculate the dipole autocorrelation function and find that our simulations\nare well-described by a stretched exponential decay, from which we calculate\nthe {\\it orientational autocorrelation time} $\\tau_{a}$. Second, we define a\nsecond characteristic time, namely the time required for the randomization of\nmolecular dipole orientation, the {\\it self-dipole randomization time}\n$\\tau_{r}$, which is an upper limit on $\\tau_{a}$; we find that\n$\\tau_{r}\\approx 5 \\tau_{a}$. Third, to check if there are correlated domains\nof dipoles in water which have large relaxation times compared to the\nindividual dipoles, we calculate the randomization time $\\tau_{\\rm box}$ of the\nsite-dipole field, the net dipole moment formed by a set of molecules belonging\nto a box of edge $L_{\\rm box}$. We find that the {\\it site-dipole randomization\ntime} $\\tau_{\\rm box}\\approx 2.5 \\tau_{a}$ for $L_{\\rm box}\\approx 3$\\AA, i.e.\nit is shorter than the same quantity calculated for the self-dipole. Finally,\nwe find that the orientational correlation length is short even at low $T$.",
        "positive": "Asymmetric electrostatic properties of an electric double layer: a\n  generalized Poisson-Boltzmann approach taking into account non-uniform size\n  effects and water polarization: We theoretically study electrostatic properties of electric double layer\nusing a generalized Poisson-Boltzmann approach taking into account the\norientational ordering of water dipoles and the excluded volume effect of water\nmolecules as well as those of positive and negative ions with different sizes\nin electrolyte solution. Our approach enables one to predict that the number\ndensities of water molecules, counterions and coions and the permittivity of\nelectrolyte solution close to a charged surface, asymmetrically vary depending\non both of sign and magnitude of the surface charge density and the volume of\ncounterion. We treat several phenomena in more detail. Firstly, an increase in\nthe volume of counterions and an increase in the surface charge density can\ncause the position of the minimum number density of water molecules to be\nfarther from the charged surface. Secondly, width of the range of voltage in\nwhich the properties at the charged surface symmetrically vary decreases with\nincreasing bulk salt concentration. In addition, we show that the excluded\nvolume effect of water molecules and the orientational ordering of water\ndipoles can lead to early onset and lowering of the maximum of electric\ncapacitance according to surface voltage. Our approach and results can be\napplied to describing electrostatic properties of biological membranes and\nelectric double layer capacitor for which excluded volume effects of water\nmolecules and ions with different sizes may be important."
    },
    {
        "anchor": "Dynamic heterogeneities and non-Gaussian behavior in two-dimensional\n  randomly confined colloidal fluids: A binary mixture of super-paramagnetic colloidal particles is confined\nbetween glass plates such that the large particles become fixed and provide a\ntwo-dimensional disordered matrix for the still mobile small particles, which\nform a fluid. By varying fluid and matrix area fractions and tuning the\ninteractions between the super-paramagnetic particles via an external magnetic\nfield, different regions of the state diagram are explored. The mobile\nparticles exhibit delocalized dynamics at small matrix area fractions and\nlocalised motion at high matrix area fractions, and the localization transition\nis rounded by the soft interactions [T. O. E. Skinner et al, Phys. Rev. Lett.\n{\\bf 111}, 128301 (2013)]. Expanding on previous work, we find the dynamics of\nthe tracers to be strongly heterogeneous and show that molecular dynamics\nsimulations of an ideal gas confined in a fixed matrix exhibit similar\nbehavior. The simulations show how these soft interactions make the dynamics\nmore heterogenous compared to the disordered Lorentz gas and lead to strong\nnon-Gaussian fluctuations.",
        "positive": "Edge waves in plates with resonators: An elastic analogue of the quantum\n  valley Hall effect: We investigate elastic periodic structures characterized by topologically\nnontrivial bandgaps supporting backscattering suppressed edge waves. These edge\nwaves are topologically protected and are obtained by breaking inversion\nsymmetry within the unit cell. Examples for discrete one and two-dimensional\nlattices elucidate the concept and illustrate parallels with the quantum valley\nHall effect. The concept is implemented on an elastic plate featuring an array\nof resonators arranged according to a hexagonal topology. The resulting\ncontinuous structures have non-trivial bandgaps supporting edge waves at the\ninterface between two media having different topological invariants. The\ntopological properties of the considered configurations are predicted by unit\ncell and finite strip dispersion analyses. Numerical simulations on finite\nstructures demonstrate edge wave propagation for excitation at frequencies\nbelonging to the bulk bandgaps. The considered plate configurations define a\nframework for the implementation of topological concepts on continuous elastic\nstructures of potential engineering relevance."
    },
    {
        "anchor": "Active Matter Shepherding and Clustering in Inhomogeneous Environments: We consider a mixture of active and passive run-and-tumble disks in an\ninhomogeneous environment where only half of the sample contains quenched\ndisorder or pinning. The disks are initialized in a fully mixed state of\nuniform density. We identify several distinct dynamical phases as a function of\nmotor force and pinning density. At high pinning densities and high motor\nforces, there is a two step process initiated by a rapid accumulation of both\nactive and passive disks in the pinned region, which produces a large density\ngradient in the system. This is followed by a slower species phase separation\nprocess where the inactive disks are shepherded by the active disks into the\npin-free region, forming a non-clustered fluid and producing a more uniform\ndensity with species phase separation. For higher pinning densities and low\nmotor forces, the dynamics becomes very slow and the system maintains a strong\ndensity gradient. For weaker pinning and large motor forces, a floating\nclustered state appears and the time averaged density of the system is uniform.\nWe illustrate the appearance of these phases in a dynamic phase diagram.",
        "positive": "An additive framework for kirigami design: We present an additive approach for the inverse design of kirigami-based\nmechanical metamaterials by focusing on the empty (negative) spaces instead of\nthe solid tiles. By considering each negative space as a four-bar linkage, we\nidentify a simple recursive relationship between adjacent linkages, yielding an\nefficient method for creating kirigami patterns. This allows us to solve the\nkirigami design problem using elementary linear algebra, with compatibility,\nreconfigurability and rigid-deployability encoded into an iterative procedure\ninvolving simple matrix multiplications. The resulting linear design strategy\ncircumvents the solution of a non-convex global optimization problem and allows\nus to control the degrees of freedom in the deployment angle field, linkage\noffsets and boundary conditions. We demonstrate this by creating a large\nvariety of rigid-deployable, compact, reconfigurable kirigami patterns. We then\nrealize our kirigami designs physically using two simple but effective\nfabrication strategies with very different materials. Altogether, our additive\napproaches present routes for efficient mechanical metamaterial design and\nfabrication based on ori/kirigami art forms."
    },
    {
        "anchor": "Deforming polar active matter in a scalar field gradient: Active matter with local polar or nematic order is subject to the well-known\nSimha-Ramaswamy instability. It is so far unclear how, despite this\ninstability, biological tissues can undergo robust active anisotropic\ndeformation during animal morphogenesis. Here we show that protein\nconcentration gradients (e.g. morphogen gradients), which are known to control\nlarge-scale coordination among cells, can stabilize such deformations. To this\nend, we study a hydrodynamic model of an active polar material. To account for\nthe effect of the protein gradient, the polar field is coupled to the\nboundary-provided gradient of a scalar field that also advects with material\nflows. Focusing on the large system size limit, we show in particular: (i) The\nsystem can be stable for an effectively extensile coupling between scalar field\ngradient and active stresses, i.e. gradient-extensile coupling, while it is\nalways unstable for a gradient-contractile coupling. Intriguingly, there are\nmany systems in the biological literature that are gradient-extensile, while we\ncould not find any that are clearly gradient-contractile. (ii) Stability is\nstrongly affected by the way polarity magnitude is controlled. Taken together,\nour findings, if experimentally confirmed, suggest new developmental principles\nthat are directly rooted in active matter physics.",
        "positive": "Understanding and controlling hexagonal patterns of wrinkles in\n  neo-Hookean elastic bilayer structures: A controlled surface wrinkling pattern has been widely used in diverse\napplications, such as stretchable electronics, smart windows, and haptics.\nHere, we focus on hexagonal wrinkling patterns because of their great\npotentials in realizing anisotropic and tunable friction and serving as a\ndynamical template for making non-flat thin films through self-assembling\nprocesses. We employ large-scale finite element simulations of a bilayer\nneo-Hookean solid (e.g., a film bonded on a substrate) to explore mechanical\nprinciples that govern the formation of hexagonal wrinkling patterns and\nstrategies for making nearly perfect hexagonal patterns. In our model, the\nwrinkling instabilities are driven by the confined film expansion. Our results\nindicate robust hexagonal patterns exist at a relatively small modulus mismatch\n(on the order of 10) between the film and substrate. Besides, the film\nexpansion should not exceed the onset of wrinkling value too much to avoid\npost-buckling patterns. By harnessing the imperfection insensitivity of\none-dimension sinusoidal wrinkles, we apply a sequential loading to the bilayer\nstructure to produce the nearly perfect hexagonal patterns. Lastly, we discuss\nthe connection between the simple bilayer model and the gradient structures\ncommonly existed in experiments."
    },
    {
        "anchor": "Traveling and resting crystals in active systems: A microscopic field theory for crystallization in active systems is proposed\nwhich unifies the phase-field-crystal model of freezing with the Toner-Tu\ntheory for self-propelled particles. A wealth of different active crystalline\nstates are predicted and characterized. In particular, for increasing strength\nof self-propulsion, a transition from a resting crystal to a traveling\ncrystalline state is found where the particles migrate collectively while\nkeeping their crystalline order. Our predictions, which are verifiable in\nexperiments and in particle-resolved computer simulations, provide a starting\npoint for the design of new active materials.",
        "positive": "Viscoelastic Taylor-Couette instability of shear banded flow: We study numerically shear banded flow in planar and curved Couette\ngeometries. Our aim is to explain two recent observations in shear banding\nsystems of roll cells stacked in the vorticity direction, associated with an\nundulation of the interface between the bands. Depending on the degree of cell\ncurvature and on the material's constitutive properties, we find either (i) an\ninstability of the interface between the bands driven by a jump in second\nnormal stress across it; or (ii) a bulk viscoelastic Taylor Couette instability\nin the high shear band driven by a large first normal stress within it. Both\nlead to roll cells and interfacial undulations, but with a different signature\nin each case. Our work thereby suggests a different origin for the roll cells\nin each of the recent experiments."
    },
    {
        "anchor": "Viscoelastic response of impact process on dense suspensions: We numerically study impact processes on dense suspensions using the lattice\nBoltzmann method to elucidate the connection between the elastic rebound of an\nimpactor and relations among the impact speed $u_0$, maximum force acting on\nthe impactor $F_{\\rm max}$, and elapsed time $t_{\\rm max}$ to reach $F_{\\rm\nmax}$. We find that $t_{\\rm max}$ emerges in the early stage of the impact,\nwhile the rebound process takes place in the late stage. We find a crossover of\n$F_{\\rm max}$ from $u_0$ independent regime for low $u_0$ to a power law regime\nsatisfying $F_{\\rm max}\\propto u_0^\\alpha$ with $\\alpha\\approx 1.5$ for high\n$u_0$. Similarly, $t_{\\rm max}$ satisfies $t_{\\rm max}\\propto u_0^{\\beta}$ with\n$\\beta\\approx -0.5$ for high $u_0$. Both power-law relations for $F_{\\rm max}$\nand $t_{\\rm max}$ versus $u_0$ for high $u_0$ are independent of the system\nsize, but the rebound phenomenon strongly depends on the depth of the container\nfor suspensions. Thus, we indicate that the rebound phenomenon is not directly\nrelated to the relations among $u_0$, $F_{\\rm max}$ and $t_{\\rm max}$. We\npropose a floating + force chain model, where the rebound process is caused by\nan elastic term that is proportional to the number of the connected force\nchains from the impactor to the bottom plate. On the other hand, there are no\nelastic contributions in the relations for $F_{\\rm max}$ and $t_{\\rm max}$\nagainst $u_0$ because of the absence of percolated force chains in the early\nstage. This phenomenology predicts $F_{\\rm max}\\propto u_0^{3/2}$ and $t_{\\rm\nmax}\\propto u_0^{-1/2}$ for high $u_0$ and also recovers the behavior of the\nimpactor quantitatively even if there is the rebound process.",
        "positive": "Dynamics of charged gibbsite platelets in the isotropic phase: We report on depolarized and non-depolarized dynamic light scattering, static\nlight scattering, and static viscosity measurements on interacting charged\ngibbsite platelets suspended in dimethyl sulfoxide (DMSO). The average\ncollective and (long-time) translational self-diffusion coefficients, and the\nrotational diffusion coefficient, have been measured as functions of the\nplatelet volume fraction \\phi, up to the isotropic-liquid crystal (I/LC)\ntransition. The non-depolarized intensity autocorrelation function, measured at\nlow scattering wavenumbers, consists of a fast and a slowly decaying mode which\nwe interpret as the orientationally averaged collective and translational\nself-diffusion coefficients, respectively. Both the rotational and the\nlong-time self-diffusion coefficients decrease very strongly, by more than two\norders of magnitude, in going from the very dilute limit to the I/LC transition\nconcentration. A similarly strong decrease, with increasing \\phi, is observed\nfor the inverse zero-strain limiting static shear viscosity. With increasing\n\\phi, increasingly strong shear-thinning is observed, accompanied by a\nshrinking of the low shear-rate Newtonian plateau. The measured diffusion\ncoefficients are interpreted theoretically in terms of a simple model of\neffective charged spheres interacting by a screened Coulomb potential, with\nhydrodynamic interactions included. The disk-like particle shape, and the\nmeasured particle radius and thickness polydispersities, enter into the model\ncalculations via the scattering amplitudes. The interaction-induced enhancement\nof the collective diffusion coefficient by more than a factor of 20 at larger\nvolume fractions is well captured in the effective sphere model, whereas the\nstrong declines both of the experimental translational and rotational\nself-diffusion coefficients are underestimated."
    },
    {
        "anchor": "Active matter: quantifying the departure from equilibrium: Active matter systems are driven out of equilibrium at the level of\nindividual constituents. One widely studied class are systems of athermal\nparticles that move under the combined influence of interparticle interactions\nand self-propulsions, with the latter evolving according to the\nOrnstein-Uhlenbeck stochastic process. Intuitively, these so-called active\nOrnstein-Uhlenbeck particles (AOUPs) systems are farther from equilibrium for\nlonger self-propulsion persistence times. Quantitatively, this is confirmed by\nthe increasing equal-time velocity correlations (which are trivial in\nequilibrium) and by the increasing violation of the Einstein relation between\nthe self-diffusion and mobility coefficients. In contrast, the entropy\nproduction rate, calculated from the ratio of the probabilities of the position\nspace trajectory and its time-reversed counterpart, has a non-monotonic\ndependence on the persistence time. Thus, it does not properly quantify the\ndeparture of AOUPs systems from equilibrium.",
        "positive": "Random very loose packs: We measure the number Omega(phi) of mechanically stable states of volume\nfraction phi of a granular assembly under gravity. The granular entropy S(phi)\n= log Omega(phi) vanishes both at high density, at phi = phi_rcp, and a low\ndensity, at phi = phi_rvlp, where phi_rvlp is a new lower bound we call random\nvery loose pack. phi_rlp is the volume fraction where the entropy is maximal.\nThese findings allow for a clear explanation of compaction experiments, and\nprovide the first first-principle definition of the random loose volume\nfraction. In the context of the statistical mechanics approach to static\ngranular materials, states with phi < phi_rlp are characterized by a negative\ntemperature."
    },
    {
        "anchor": "Colloids in liquid crystals: a lattice Boltzmann study: We propose a hybrid lattice Boltzmann algorithm to simulate the hydrodynamics\nof colloidal particles inside a liquid crystalline host. To validate our\nalgorithm, we study the static and the microrheology of a colloid in a nematic,\nwith tangential anchoring of the director field at the particle surface, and we\nconfirm theories and experiments showing that the drag force in a nematic is\nmarkedly anisotropic. We then apply our method to consider the case of a\ncolloid inside a cholesteric, and with normal anchoring at the surface. We show\nthat by tuning the ratio between particle size and cholesteric pitch it is\npossible to control the defect configuration around the particle, and to\nstabilise novel figure-of-eight or highly twisted loops close to the colloid\nsurface.",
        "positive": "The Twist Bend Nematic: A Case of Mistaken Identity: We review the physics underlying Meyer's conjecture of how macroscopic-scale\ntwist and bend conspire within the Frank-Oseen elasticity theory of nematics to\ncreate a heliconical arrangement of the uniaxial, apolar nematic director, the\nso-called \"twist bend nematic\" $\\rm N_{TB}$. We show that since 2011 a second,\nlower-temperature nematic phase observed in odd methylene-linked cyanobiphenyl\ndimers discovered by Toriumi and called $\\rm N_X$, has been incorrectly\nidentified as $\\rm N_{TB}$. Moreover, as more quantitative data on the $\\rm\nN_X$ emerged, Meyer's simple prediction has been distorted to accommodate those\nfindings. In fact, the molecular organization in the $\\rm N_X$ conforms to the\n$\\rm N_{PT}$ phase, a polar, twisted arrangement of nonlinear mesogens advanced\nin 2016. The attributes of the $\\rm N_{PT}$ are summarized and differentiated\nfrom those of the $\\rm N_{TB}$ in an effort to contribute to a better\nunderstanding of the $\\rm N_X$ phase and, equally important, to encourage\nresearchers to continue to search for a liquid crystal that exhibits Meyer's\npioneering theoretical suggestion, namely that form-chirality can exist in\nsimple nematics composed of achiral molecules."
    },
    {
        "anchor": "X-ray computerized tomography observation of Lycopodium paste\n  incorporating memory of shaking: In a uniform layer consisting of a mixture of granular material and liquid,\nit is known that desiccation cracks exhibit various anisotropic patterns that\ndepend on the nature of the shaking that the layer experienced before drying.\nThe existence of this effect implies that information regarding the direction\nof shaking is retained as a kind of memory in the arrangements of granular\nparticles. In this work we make measurements in paste composed of Lycopodium\npowder using microfocus x-ray computerized tomography ($\\mu$CT) in order to\ninvestigate the three-dimensional arrangements of particles. We find\nshaking-induced anisotropic arrangements of neighboring particles and density\nfluctuations forming interstices mainly in the lower part of the layer. We\ncompare the observed properties of these arrangements with numerical results\nobtained in the study of a model of non-Brownian particles under shear\ndeformation. In the experimental system, we also observe crack tips in the\n$\\mu$CT images and confirm that these cracks grow along interstices in the\ndirection perpendicular to the initial shaking.",
        "positive": "Hydrodynamic theory of an electron gas: The generalised hydrodynamic theory of an electron gas, which does not rely\non an assumption of a local equilibrium, is derived as the long-wave limit of a\nkinetic equation. Apart from the common hydrodynamics variables the theory\nincludes the tensor fields of the higher moments of the distribution function.\nIn contrast to the Bloch hydrodynamics, the theory leads to the correct plasmon\ndispersion and in the low frequency limit recovers the Navies-Stocks\nhydrodynamics. The linear approximation to the generalised hydrodynamics is\nclosely related to the theory of highly viscous fluids."
    },
    {
        "anchor": "Design of linear block copolymers and ABC star terpolymers that produce\n  two length scales at phase separation: Quasicrystals (materials with long range order but without the usual spatial\nperiodicity of crystals) were discovered in several soft matter systems in the\nlast twenty years. The stability of quasicrystals has been attributed to the\npresence of two prominent length scales in a specific ratio, which is 1.93 for\nthe twelve-fold quasicrystals most commonly found in soft matter. We propose\ndesign criteria for block copolymers such that quasicrystal-friendly length\nscales emerge at the point of phase separation from a melt, basing our\ncalculations on the Random Phase Approximation. We consider two block copolymer\nfamilies: linear chains containing two different monomer types in blocks of\ndifferent lengths, and ABC star terpolymers. In all examples, we are able to\nidentify parameter windows with the two length scales having a ratio of 1.93.\nThe models that we consider that are simplest for polymer synthesis are, first,\na monodisperse A_L B A_S B melt and, second, a model based on random reactions\nfrom a mixture of A_L, A_S and B chains: both feature the length scale ratio of\n1.93 and should be relatively easy to synthesise.",
        "positive": "Measuring the linear and nonlinear elastic properties of brain tissue\n  with shear waves and inverse analysis: We use supersonic shear wave imaging (SSI) technique to measure not only the\nlinear but also the nonlinear elastic properties of brain matter. Here, we\ntested six porcine brains ex vivo and measured the velocities of the plane\nshear waves induced by acoustic radiation force at different states of\npre-deformation when the ultrasonic probe is pushed into the soft tissue. We\nrelied on an inverse method based on the theory governing the propagation of\nsmall-amplitude acoustic waves in deformed solids to interpret the experimental\ndata. We found that, depending on the subjects, the resulting initial shear\nmodulus mu0 varies from 1.8 to 3.2 kPa, the stiffening parameter b of the\nhyperelastic Demiray-Fung model from 0.13 to 0.73, and the third- (A) and\nfourth-order (D) constants of weakly nonlinear elasticity from -1.3 to -20.6\nkPa and from 3.1 to 8.7 kPa, respectively. Paired t-test performed on the\nexperimental results of the left and right lobes of the brain shows no\nsignificant difference. These values are in line with those reported in the\nliterature on brain tissue, indicating that the SSI method, combined to the\ninverse analysis, is an efficient and powerful tool for the mechanical\ncharacterization of brain tissue, which is of great importance for computer\nsimulation of traumatic brain injury and virtual neurosurgery."
    },
    {
        "anchor": "Substrate concentration dependence of the diffusion-controlled\n  steady-state rate constant: The Smoluchowski approach to diffusion-controlled reactions is generalized to\ninteracting substrate particles by including the osmotic pressure and\nhydrodynamic interactions of the nonideal particles in the Smoluchoswki\nequation within a local-density approximation. By solving the strictly\nlinearized equation for the time-independent case with absorbing boundary\nconditions, we present an analytic expression for the diffusion-limited\nsteady-state rate constant for small substrate concentrations in terms of an\neffective second virial coefficient B_2*. Comparisons to Brownian dynamics\nsimulations excluding HI show excellent agreement up to bulk number densities\nof B_2* rho_0 < 0.4 for hard sphere and repulsive Yukawa-like interactions\nbetween the substrates. Our study provides an alternative way to determine the\nsecond virial coefficient of interacting macromolecules experimentally by\nmeasuring their steady-state rate constant in diffusion-controlled reactions at\nlow densities.",
        "positive": "Tilt-induced polar order and topological defects in growing bacterial\n  populations: Rod-shaped bacteria, such as Escherichia coli, commonly live forming mounded\ncolonies. They initially grow two-dimensionally on a surface and finally\nachieve three-dimensional growth. While it was recently reported that\nthree-dimensional growth is promoted by topological defects of winding number\n$+1/2$ in populations of motile bacteria, how cellular alignment plays a role\nin non-motile cases is largely unknown. Here, we investigate the relevance of\ntopological defects in colony formation processes of non-motile E. coli\npopulations, and found that both $\\pm 1/2$ topological defects contribute to\nthe three-dimensional growth. Analyzing the cell flow in the bottom layer of\nthe colony, we observe that $+1/2$ defects attract cells and $-1/2$ defects\nrepel cells, in agreement with previous studies on motile cells, in the initial\nstage of the colony growth. However, later, cells gradually flow toward $-1/2$\ndefects as well, exhibiting a sharp contrast to the existing knowledge. By\ninvestigating three-dimensional cell orientations by confocal microscopy, we\nfind strong vertical tilting of cells near the defects. Crucially, this leads\nto the emergence of a polar order in the otherwise nematic two-dimensional cell\norientation. We extend the theory of active nematics by incorporating this\npolar order and the vertical tilting, which successfully explains the influx\ntoward $-1/2$ defects in terms of a polarity-induced force. Our work reveals\nthat three-dimensional cell orientations may result in drastic changes in\nproperties of active nematics, especially those of topological defects, which\nmay be generically relevant in active matter systems driven by cellular growth\ninstead of self-propulsion."
    },
    {
        "anchor": "Flow of gluten with tunable protein composition: from stress undershoot\n  to stress overshoot and strain hardening: Understanding the origin of the unique rheological properties of wheat\ngluten, the protein fraction of wheat grain, is crucial in bread-making\nprocesses and questions scientists since polymeric glutenins. To better\nunderstand the respective role of the different classes of proteins in the\nsupramolecular structure of gluten and its link to the material properties, we\ninvestigate here concentrated dispersions of gluten proteins in water with a\nfixed total protein concentration but variable composition in gliadin and\nglutenin. Linear viscoelasticity measurements show a gradual increase of the\nviscosity of the samples as the glutenin mass content increases from 7 to 66%.\nWhile the gliadin-rich samples are microphase-separated viscous fluids,\nhomogeneous and transparent pre-gel and gels are obtained with the replacement\nof gliadin by glutenin. To unravel the flow properties of the gluten samples,\nwe perform shear start-up experiments at different shear-rates. In accordance\nwith the linear viscoelastic signature, three classes of behaviour are\nevidenced depending on the protein composition. As samples get depleted in\ngliadin and enriched in glutenin, distinctive features are measured: (i)\nviscosity undershoot suggesting droplet elongation for microphase-separated\ndispersions, (ii) stress overshoot and partial structural relaxation for\nnear-critical pre-gels, and (iii) strain hardening and flow instabilities of\ngels. We discuss the experimental results by analogy with the behaviour of\nmodel systems, including viscoelastic emulsions, branched polymer melts and\ncritical gels, and provide a consistent physical picture of the supramolecular\nfeatures of the three classes of protein dispersions.",
        "positive": "Novel polymer nanocomposite composed of organic nanoparticles via\n  self-assembly: We report a novel class of polymer nanocomposite composed of organic\nnanoparticles dispersed in polymer matrix, with the particle sizes of 30-120 nm\nin radius. The organic nanoparticles were formed by the self-assembly of\nprotonated poly(4-vinyl-pyridine)-r-poly(acrylonitrile) and amphiphilic metanil\nyellow dye molecules through electrostatic interactions in aqueous solution. A\nstrongly broadened Raman shift band was probed, suggesting the presence of\nenhanced optoelectronic property from the polymer nanocomposite. Here, using\nrandom-copolymer polyelectrolytes and mesogenic amphiphiles as the designed\nbuilding blocks for self-assembly, a new approach is acutally provided to\nfabricate organic nanoparticles."
    },
    {
        "anchor": "Dynamic correlation functions and Boltzmann Langevin approach for driven\n  one dimensional lattice gas: We study the dynamics of the totally asymmetric exclusion process with open\nboundaries by phenomenological theories complemented by extensive Monte-Carlo\nsimulations. Upon combining domain wall theory with a kinetic approach known as\nBoltzmann-Langevin theory we are able to give a complete qualitative picture of\nthe dynamics in the low and high density regime and at the corresponding phase\nboundary. At the coexistence line between high and low density phases we\nobserve a time scale separation between local density fluctuations and\ncollective domain wall motion, which are well accounted for by the\nBoltzmann-Langevin and domain wall theory, respectively. We present Monte-Carlo\ndata for the correlation functions and power spectra in the full parameter\nrange of the model.",
        "positive": "Ring-Pattern Dynamics in Smectic-C* and Smectic-C_A* Freely Suspended\n  Liquid Crystal Films: Ring patterns of concentric 2pi-solitons in molecular orientation, form in\nfreely suspended chiral smectic-C films in response to an in-plane rotating\nelectric field. We present measurements of the zero-field relaxation of ring\npatterns and of the driven dynamics of ring formation under conditions of\nsynchronous winding, and a simple model which enables their quantitative\ndescription in low polarization DOBAMBC. In smectic C_A* TFMHPOBC we observe an\nodd-even layer number effect, with odd number layer films exhibiting order of\nmagnitude slower relaxation rates than even layer films. We show that this rate\ndifference is due to much larger spontaneous polarization in odd number layer\nfilms."
    },
    {
        "anchor": "Spontaneous Oscillations of Collective Molecular Motors: We analyze a simple stochastic model to describe motor molecules which\ncooperate in large groups and present a physical mechanism which can lead to\noscillatory motion if the motors are elastically coupled to their environment.\nBeyond a critical fuel concentration, the non-moving state of the system\nbecomes unstable with respect to a mode with angular frequency omega. We\npresent a perturbative description of the system near the instability and\ndemonstrate that oscillation frequencies are determined by the typical\ntimescales of the motors.",
        "positive": "Influence of Confinement on Dynamical Heterogeneities in Dense Colloidal\n  Samples: We study a dense colloidal suspension confined between two quasiparallel\nglass plates as a model system for a supercooled liquid in confined geometries.\nWe directly observe the three-dimensional Brownian motion of the colloidal\nparticles using laser scanning confocal microscopy. The particles form dense\nlayers along the walls, but crystallization is avoided as we use a mixture of\ntwo particle sizes. A normally liquid-like sample, when confined, exhibits\nslower diffusive motion. Particle rearrangements are spatially heterogeneous,\nand the shapes of the rearranging regions are strongly influenced by the\nlayering. These rearranging regions become more planar upon confinement. The\nwall-induced layers and changing character of the spatially heterogeneous\ndynamics appear strongly connected to the confinement induced glassiness."
    },
    {
        "anchor": "Rectification of Swimming Bacteria and Self Driven Particle Systems by\n  Arrays of Asymmetric Barriers: We show that the recent experimental observation of the rectification of\nswimming bacteria in a system with an array of asymmetric barriers occurs due\nto the ballistic component of the bacteria trajectories introduced by the\nbacterial \"motor.\" Each bacteria selects a random direction for motion and then\nmoves in this direction for a fixed period of time before randomly changing its\norientation and moving in a new direction. In the limit where the bacteria\nundergo only Brownian motion, rectification by the barriers does not occur. We\nalso examine the effects of steric interactions between the bacteria and\nobserve a clogging effect upon increasing the bacteria density.",
        "positive": "Meandering instability of air flow in a granular bed: self-similarity\n  and fluid-solid duality: Meandering instability is familiar to everyone through river meandering or\nsmall rivulets of rain flowing down a windshield. However, its physical\nunderstanding is still premature, although it could inspire researchers in\nvarious fields, such as nonlinear science, fluid mechanics and geophysics, to\nresolve their long-standing problems. Here, we perform a small-scale experiment\nin which air flow is created in a thin granular bed to successfully find a\nmeandering regime, together with other remarkable fluidized regimes, such as a\nturbulent regime. We discover that phase diagrams of the flow regimes for\ndifferent types of grains can be universally presented as functions of the flow\nrate and the granular-bed thickness when the two quantities are properly\nrenormalized. We further reveal that the meandering shapes are self-similar as\nwas shown for meandering rivers. The experimental findings are explained by\ntheory, with elucidating the physics. The theory is based on force balance, a\nminimum-dissipation principle, and a linear-instability analysis of a continuum\nequation that takes into account the fluid-solid duality, i.e., the existence\nof fluidized and solidified regions of grains along the meandering path. The\npresent results provide fruitful links to related issues in various fields,\nincluding fluidized bed reactors in industry."
    },
    {
        "anchor": "Precise algorithm to generate random sequential adsorption of hard\n  polygons at saturation: Random sequential adsorption (RSA) is a time-dependent packing process, in\nwhich particles of certain shapes are randomly and sequentially placed into an\nempty space without overlap. In the infinite-time limit, the density approaches\na \"saturation\" limit. Although this limit has attracted particular research\ninterest, the majority of past studies could only probe this limit by\nextrapolation. We have previously found an algorithm to reach this limit using\nfinite computational time for spherical particles, and could thus determine the\nsaturation density of spheres with high accuracy. In this paper, we generalize\nthis algorithm to generate saturated RSA packings of two-dimensional polygons.\nWe also calculate the saturation density for regular polygons of three to ten\nsides, and obtain results that are consistent with previous,\nextrapolation-based studies.",
        "positive": "Magnetic Polymer Models for Epigenetics-Driven Chromosome Folding: Epigenetics is a driving force of important and ubiquitous phenomena in\nnature such as cell differentiation or even metamorphosis. Oppositely to its\nwidespread role, understanding the biophysical principles that allow\nepigenetics to control and rewire gene regulatory networks remains an open\nchallenge. In this work we study the effects of epigenetic modifications on the\nspatial folding of chromosomes -- and hence on the expression of the underlying\ngenes -- by mapping the problem to a class of models known as magnetic\npolymers. In this work we show that a first-order phase transition underlies\nthe simultaneous spreading of certain epigenetic marks and the conformational\ncollapse of a chromosome. Further, we describe Brownian Dynamics simulations of\nthe model in which the topology of the polymer and thermal fluctuations are\nfully taken into account and that confirms our mean-field predictions.\nExtending our models to allow for non-equilibrium terms yields new stable\nphases which qualitatively agrees with observations in vivo. Our results show\nthat statistical mechanics techniques applied to models of magnetic polymers\ncan be successfully exploited to rationalize the outcomes of experiments\ndesigned to probe the interplay between a dynamic epigenetic landscape and\nchromatin organization."
    },
    {
        "anchor": "Microrheology near jamming: The jamming transition is a nonequilibrium critical phenomenon, which governs\ncharacteristic mechanical properties of jammed soft materials, such as pastes,\nemulsions, and granular matters. Both experiments and theory of jammed soft\nmaterials have revealed that the complex modulus measured by conventional\nmacrorheology exhibits a characteristic frequency dependence. Microrheology is\na new type of method to obtain the complex modulus, which transforms the\nmicroscopic motion of probes to the complex modulus through the generalized\nStokes relation (GSR). Although microrheology has been applied to jammed soft\nmaterials, its theoretical understanding is limited. In particular, the\nvalidity of the GSR near the jamming transition is far from obvious since there\nis a diverging length scale $l_c$, which characterizes the heterogeneous\nresponse of jammed particles. Here, we study the microrheology of jammed\nparticles by theory and numerical simulation. First, we develop a linear\nresponse formalism to calculate the response function of the probe particle,\nwhich is transformed to the complex modulus via the GSR. Then, we apply our\nformalism to a numerical model of jammed particles and find that the storage\nand loss modulus follow characteristic scaling laws near the jamming\ntransition. Importantly, the observed scaling law coincides with that in\nmacrorheology, which indicates that the GSR holds even near the jamming\ntransition. We rationalize this equivalence by asymptotic analysis of the\nobtained formalism and numerical analysis on the displacement field of jammed\nparticles under a local perturbation.",
        "positive": "Equilibrium properties of magnetic filament suspensions: Langevin dynamics is used to study equilibrium properties of the suspension\nof magnetic filaments (chains of nanoparticles permanently crosslinked with\npolymers). It is shown that the filament suspension generally has a larger\nmagnetic susceptibility than the system of unlinked nanoparticles with the same\naverage particle concentration. However, actual susceptibility gain strongly\ndepends on length and flexibility of filaments. It is also shown that in a\nstrong gravitational (centrifugal) field sedimentation profiles of filaments\nare less homogeneous than that of unlinked particles. The spatial distribution\nof filaments weakly depends on the intensity of interparticle dipole-dipole\ninteractions."
    },
    {
        "anchor": "Scenario of strongly non-equilibrium Bose-Einstein condensation: Large scale numerical simulations of the Gross-Pitaevskii equation are used\nto elucidate the self-evolution of a Bose gas from a strongly non-equilibrium\ninitial state. The stages of the process confirm and refine the theoretical\nscenario of Bose-Einstein condensation developed by Svistunov, Kagan, and\nShlyapnikov [1-3]: the system evolves from the regime of weak turbulence to\nsuperfluid turbulence, via states of strong turbulence in the long-wavelength\nregion of energy space.",
        "positive": "Interaction between Heterogeneously Charged Surfaces: Surface Patches\n  and Charge Modulation: When solid surfaces are immersed in aqueous solutions, some of their charges\ncan dissociate and leave behind charge patches on the surface. Although the\ncharges are distributed heterogeneously on the surface, most of the theoretical\nmodels treat them as homogeneous. For overall non-neutral surfaces, the\nassumption of surface charge homogeneity is rather reasonable, since the\nleading terms of two such interacting surfaces depend on the non-zero average\ncharge. However, for overall neutral surfaces, the nature of the surface charge\ndistribution is crucial in determining the inter-surface interaction. In the\npresent work we study the interaction between two charged surfaces across an\naqueous solution for several charge distributions. The analysis is preformed\nwithin the framework of the linearized Poisson-Boltzmann theory. For periodic\ncharge distributions the interaction is found to be repulsive at small\nseparations, unless the two surface distributions are completely out-of-phase\nwith respect to each other. For quenched random charge distributions we find\nthat due to the presence of the ionic solution in between the surfaces, the\ninter-surface repulsion dominates over the attraction in the linear regime of\nthe Poisson-Boltzmann theory. The effect of quenched charge heterogeneity is\nfound to be particularly substantial in the case of large charge domains."
    },
    {
        "anchor": "Brambilla et al. Reply to a Comment by J. Reinhardt et al. on \"Probing\n  the equilibrium dynamics of colloidal hard spheres above the mode-coupling\n  glass transition\": G. Brambilla et al. Reply to a Comment by J. Reinhardt et al. questioning the\nexistence of equilibrium dynamics above the critical volume fraction of\ncolloidal hard spheres predicted by mode coupling theory.",
        "positive": "Instability in dynamic fracture and the failure of the classical theory\n  of cracks: Cracks, the major vehicle for material failure, tend to accelerate to high\nvelocities in brittle materials. In three-dimensions, cracks generically\nundergo a micro-branching instability at about 40% of their sonic limiting\nvelocity. Recent experiments showed that in sufficiently thin systems cracks\nunprecedentedly accelerate to nearly their limiting velocity without\nmicro-branching, until they undergo an oscillatory instability. Despite their\nfundamental importance and apparent similarities to other instabilities in\ncondensed-matter physics and materials science, these dynamic fracture\ninstabilities remain poorly understood. They are not described by the classical\ntheory of cracks, which assumes that linear elasticity is valid inside a\nstressed material and uses an extraneous local symmetry criterion to predict\ncrack paths. Here we develop a model of two-dimensional dynamic brittle\nfracture capable of predicting arbitrary paths of ultra-high-speed cracks in\nthe presence of elastic nonlinearity without extraneous criteria. We show, by\nextensive computations, that cracks undergo a dynamic oscillatory instability\ncontrolled by small-scale elastic nonlinearity near the crack tip. This\ninstability occurs above a ultra-high critical velocity and features an\nintrinsic wavelength that increases proportionally to the ratio of the fracture\nenergy to an elastic modulus, in quantitative agreement with experiments. This\nratio emerges as a fundamental scaling length assumed to play no role in the\nclassical theory of cracks, but shown here to strongly influence crack\ndynamics. Those results pave the way for resolving other long-standing puzzles\nin the failure of materials."
    },
    {
        "anchor": "Structural hierarchy confers error tolerance in biological tissues: Structural hierarchy, in which materials possess distinct features on\nmultiple length scales, is ubiquitous in nature; diverse biological materials,\nsuch as bone, cellulose, and muscle, have as many as ten hierarchical levels.\nStructural hierarchy confers many mechanical advantages, including improved\ntoughness and economy of material. However, it also presents a problem: each\nhierarchical level adds a new source of assembly errors, and substantially\nincreases the information required for proper assembly. This seems to conflict\nwith the prevalence of naturally occurring hierarchical structures, suggesting\nthat a common mechanical source of hierarchical robustness may exist. However,\nour ability to identify such a unifying phenomenon is limited by the lack of a\ngeneral mechanical framework for structures exhibiting organization on\ndisparate length scales. Here, we use simulations to substantiate a generalized\nmodel for the tensile stiffness of hierarchical, stretching-stabilized,\nfilamentous networks with a nested, dilute triangular lattice structure.\nFollowing seminal work by Maxwell and others on criteria for stiff frames, we\nextend the concept of connectivity in network mechanics, and find a\nmathematically similar dependence of material stiffness upon each hierarchical\nlevel. Using this model, we find that the stiffness of such networks becomes\nless sensitive to errors in assembly with additional levels of hierarchy;\nthough surprising, we show that this result is analytically predictable from\nfirst principles, and thus likely model-independent. More broadly, this work\nhelps account for the success of hierarchical, filamentous materials in biology\nand materials design, and offers a heuristic for ensuring that desired material\nproperties are achieved within the required tolerance.",
        "positive": "Void Prediction During Liquid Composite Molding Processes: Wetting and\n  Capillary Phenomena: The aim of this work is to contribute in improving fibrous preforms\nimpregnation for Liquid Composite Molding (LCM) processes. The void prediction\nin LCM sparks off interest within the Composite Material elaboration because it\nrepresents a significant issue to keep the expected mechanical properties of\nthe final product. The liquid properties, the preform geometry and the flow\nconditions impact the void or bubble entrapped inside and outside the yarns.\nNevertheless, due to the complex geometry of the reinforcement, experimental\ncharacterization of bubble formation remains delicate. Thus, our study deals\nwith two simple model networks representing connected pores so called \"Pore\nDoublet Model\". A first is considering two capillaries converging on a node\n(T-junction) and a second is representing two capillaries interconnected with a\nsupplying principle. In this paper, we emphasize on microfluidic and\nmillifluidic approaches where wetting and capillary forces are significant\nduring bubble formation mechanism."
    },
    {
        "anchor": "Mechanical stress as a regulator of cell motility: The motility of a cell can be triggered or inhibited not only by an applied\nforce but also by a mechanically neutral force couple. This type of loading,\nrepresented by an applied stress and commonly interpreted as either squeezing\nor stretching, can originate from extrinsic interaction of a cell with its\nneighbors. To quantify the effect of applied stresses on cell motility we use\nan analytically transparent one-dimensional model accounting for active myosin\ncontraction and induced actin turnover. We show that stretching can polarize\nstatic cells and initiate cell motility while squeezing can symmetrize and\narrest moving cells. We show further that sufficiently strong squeezing can\nlead to the loss of cell integrity. The overall behavior of the system depends\non the two dimensionless parameters characterizing internal driving (chemical\nactivity) and external loading (applied stress). We construct a phase diagram\nin this parameter space distinguishing between, static, motile and collapsed\nstates. The obtained results are relevant for the mechanical understanding of\ncontact inhibition and the epithelial-to-mesenchymal transition.",
        "positive": "Isomorph theory prediction for the dielectric loss variation along an\n  isochrone: This paper derives a prediction for the variation of the amplitude of the\ndielectric loss from isomorph theory, and presents an experimental test of the\nprediction performed by measuring the dielectric-relaxation behavior of the van\nder Waals liquid 5-phenyl-4-ether (5PPE). The liquid is studied at isochronal\nstates in the temperature range $266-333$ K and pressure range $0.1-300$ MPa,\nfor relaxation times around $10^{-3}$ s and $10^{-4}$ s. From the isomorph\nstatement that there is structural and dynamic invariance of isomorph states in\nreduced units for Roskilde simple liquids we derive four equivalent\nisomorph-invariant terms, one of which is used in analyzing our data. It is the\nfrequency-dependent term $\\chi_{e}(f) \\rho^{\\gamma-1}$, with electric\nsusceptibility $\\chi_{e}$, density $\\rho$, and density-scaling factor $\\gamma$.\nDue to the unique design of our experimental setup, we obtain dielectric loss\ndata where the amplitude is reproducible $\\pm 0.1 \\%$. We moreover find that\nthe empty capacitance of the capacitor cell is stable within $\\pm 0.3 \\%$ in\nour measuring range and can be assumed to be constant. Using this we predict\nfor two isomorph states there is $-C_{2}\"(f)= -C_{1}\"(f) \\left(\\rho_1 / \\rho_2\n\\right)^{\\gamma-1}$ to scale the negative imaginary capacitance, where $C_{1}$\nis the capacitance measurement at ambient pressure and $C_{2}$ is the predicted\ncapacitance at elevated pressure. We visually compare the predicted and\nmeasured plots and there is good match between the two plots among the 42 pairs\nof isochronal states from the measurement."
    },
    {
        "anchor": "Electrolytic depletion interactions: We consider the interactions between two uncharged planar macroscopic\nsurfaces immersed in an electrolyte solution which are induced by interfacial\nselectivity. These forces are taken into account by introducing a depletion\nfree-energy density functional, in addition to the usual mean-field\nPoisson-Boltzmann functional. The minimization of the total free-energy\nfunctional yields the density profiles of the microions and the electrostatic\npotential. The disjoining pressure is obtained by differentiation of the total\nfree energy with respect to the separation of the surfaces, holding the range\nand strength of the depletion forces constant. We find that the induced\ninteraction between the two surfaces is always repulsive for sufficiently large\nseparations, and becomes attractive at shorter separations. The nature of the\ninduced interactions changes from attractive to repulsive at a distance\ncorresponding to the range of the depletion forces.",
        "positive": "Ring-Driven Shear Thickening in Wormlike Micelles?: The shear-thickening behaviour of wormlike micelles, at concentrations just\nbelow overlap, remains unexplained. In some cases it has recently been\nconfirmed that very slow relaxations must be present even in the quiescent\nstate -- for example, the shear thickening properties can depend on earlier\nthermal cycling. We present a speculative scenario based on the presence, just\nbelow the (apparent) overlap threshold, of large rings whose linking and\ndelinking kinetics control the shear thickening process. Equilibration between\nrings and open chains in turn controls the slow relaxations."
    },
    {
        "anchor": "Coarse-graining diblock copolymer solutions: a macromolecular version of\n  the Widom-Rowlinson model: We propose a systematic coarse-grained representation of block copolymers,\nwhereby each block is reduced to a single ``soft blob'' and effective intra- as\nwell as intermolecular interactions act between centres of mass of the blocks.\nThe coarse-graining approach is applied to simple athermal lattice models of\nsymmetric AB diblock copolymers, in particular to a Widom-Rowlinson-like model\nwhere blocks of the same species behave as ideal polymers (i.e. freely\ninterpenetrate), while blocks of opposite species are mutually avoiding walks.\nThis incompatibility drives microphase separation for copolymer solutions in\nthe semi-dilute regime. An appropriate, consistent inversion procedure is used\nto extract effective inter- and intramolecular potentials from Monte Carlo\nresults for the pair distribution functions of the block centres of mass in the\ninfinite dilution limit.",
        "positive": "Spurious velocities in lattice Boltzmann: Stationary droplets simulated by multi-phase lattice Boltzmann methods lead\nto spurious velocities around them. In this article I report the origin of\nthese spurious velocities for one example and show how they can be avoided."
    },
    {
        "anchor": "Theoretical consideration of pits recording and etching processes in\n  chalcogenide vitreous semiconductors: We propose theoretical consideration and computer modeling of information pit\nrecording and etching processes in chalcogenide vitreous semiconductors. We\ndemonstrate how to record and develop information pits with the necessary shape\nand sizes in chalcogenide photoresists using gaussian laser beam and selective\netching. It has been shown that phototransformed region cross-section could be\nalmost trapezoidal or parabolic depending on the photoresist material optical\nabsorption, recording beam power, exposure, etchant selectivity and etching\ntime. After illumination, the spatial distribution of photo-transformed\nmaterial fraction was calculated using the Kolmogorov-Awrami equation.\nAnalyzing obtained results, we derived a rather simple approximate analytical\nexpression for the dependence of the photo-transformed region width and depth\non the recording gaussian beam power, radius and exposure time. Then the\nselective etching process was simulated numerically. The obtained results\nquantitatively describes the characteristics of pits recorded by the gaussian\nlaser beam in thin layers of As40S60 chalcogenide semiconductor.",
        "positive": "Characterizing the heterogeneity of membrane liquid-ordered domains: We use a lattice model of a ternary mixture containing saturated and\nunsaturated lipids with cholesterol (Chol), to study the structural properties\ncharacterizing the coexistence between the liquid-disordered and liquid-ordered\nphases. Depending on the affinity of the saturated and unsaturated lipids, the\nsystem may exhibit macroscopic (thermodynamic) liquid-liquid phase separation,\nor be divided into small-size liquid-ordered domains surrounded by a\nliquid-disordered matrix. In both cases, it is found that the nano-scale\nstructure of the liquid-ordered regions is heterogeneous, and that they are\npartitioned into Chol-rich sub-domains and Chol-free, gel-like, nano-clusters.\nThis emerges as a characteristic feature of the liquid-ordered state, which\nhelps distinguishing between liquid-ordered domains in a two-phase mixture, and\nsimilar-looking domains in a one-phase mixture that are rich in saturated\nlipids and Chol, but are merely thermal density fluctuations. The\nnano-structure heterogeneity of the liquid-ordered phase can be detected by\nsuitable experimental spectroscopic methods, and is observed also in atomistic\ncomputer simulations."
    },
    {
        "anchor": "Propagation of sound in a Bose Einstein condensate in an optical lattice: We study the propagation of sound waves in a Bose-Einstein condensate trapped\nin a one-dimensional optical lattice. We find that the velocity of propagation\nof sound wavepackets decreases with increasing optical lattice depth, as\npredicted by the Bogoliubov theory. The strong interplay between nonlinearities\nand the periodicity of the external potential raise new phenomena which are not\npresent in the uniform case. Shock waves, for instance, can propagate slower\nthan sound waves, due to the negative curvature of the dispersion relation.\nMoreover, nonlinear corrections to the Bogoliubov theory appear to be important\neven with very small density perturbations, inducing a saturation on the\namplitude of the sound signal.",
        "positive": "Passive and active field theories for disease spreading: The worldwide COVID-19 pandemic has led to a significant growth of interest\nin the development of mathematical models that allow to describe effects such\nas social distancing measures, the development of vaccines, and mutations.\nSeveral of these models are based on concepts from soft matter theory.\nConsiderably less well investigated is the reverse direction, i.e., how results\nfrom epidemiological research can be of interest for the physics of colloids\nand polymers. In this work, we consider the SIR-DDFT model, a combination of\nthe susceptible-infected-recovered (SIR) model from epidemiology with dynamical\ndensity functional theory (DDFT) from nonequilibrium soft matter physics, which\nallows for an explicit modeling of social distancing. We extend the SIR-DDFT\nmodel both from an epidemiological perspective by incorporating vaccines,\nasymptomaticity, reinfections, and mutations, and from a soft matter\nperspective by incorporating noise and self-propulsion and by deriving a phase\nfield crystal (PFC) model that allows for a simplified description. On this\nbasis, we investigate via computer simulations how epidemiological models are\naffected by the presence of non-reciprocal interactions. This is done in a\nnumerical study of a zombie outbreak."
    },
    {
        "anchor": "Noise-Induced Collective Actuation in Active Solids: Collective actuation describes the spontaneous synchronized oscillations\ntaking place in active solids, when the elasto-active feedback, that\ngenerically couples the reorientation of the active forces and the elastic\nstress, is large enough. In the absence of noise, collective actuation takes\nthe form of a strong condensation of the dynamics on a specific pair of modes\nand their generalized harmonics. Here we report new experiments conducted with\ncentimetric active elastic structures, where collective oscillation takes place\nalong the single lowest energy mode of the system, gapped from the other modes\nbecause of the system's geometry. Combining the numerical and theoretical\nanalysis of an agent-based model, we demonstrate that this new form of\ncollective actuation is noise-induced. The effect of the noise is first\nanalyzed in a single-particle toy model that reveals the interplay between the\nnoise and the specific structure of the phase space. We then show that in the\ncontinuous limit, any finite amount of noise turns this new form of transition\nto collective actuation into a bona fide supercritical Hopf bifurcation.",
        "positive": "Resonantly-driven nanopores can serve as nanopumps: Inducing transport in electrolyte-filled nanopores with dc fields has led to\ninfluential applications ranging from nanosensors to DNA sequencing. Here we\nuse the Poisson-Nernst-Planck and Navier-Stokes equations to show that unbiased\nac fields can induce comparable directional flows in gated conical nanopores.\nThis flow exclusively occurs at intermediate driving frequencies and hinges on\nthe resonance of two competing timescales, representing space charge\ndevelopment at the ends and in the interior of the pore. We summarize the\nphysics of resonant nanopumping in an analytical model that reproduces the\nresults of numerical simulations. Our findings provide a generic route towards\nreal-time controllable flow patterns, which might find applications in\ncontrolling the translocation of particles such as small molecules or\nnanocolloids."
    },
    {
        "anchor": "Isometric bending requires local constraints on free edges: While the shape equations describing the equilibrium of an unstretchable thin\nsheet that is free to bend are known, the boundary conditions that supplement\nthese equations on free edges have remained elusive. Intuitively,\nunstretchability is captured by a constraint on the metric within the bulk.\nNaively one would then guess that this constraint is enough to ensure that the\ndeformations determining the boundary conditions on these edges respect the\nisometry constraint. If matters were this simple, unfortunately, it would imply\nunbalanced torques (as well as forces) along the edge unless manifestly\nunphysical constraints are met by the boundary geometry. In this paper we\nidentify the source of the problem: not only the local arc-length but also the\ngeodesic curvature need to be constrained explicitly on all free edges. We\nderive the boundary conditions which follow. Contrary to conventional wisdom,\nthere is no need to introduce boundary layers. This framework is applied to\nisolated conical defects, both with deficit as well, but more briefly, as\nsurplus angles. Using these boundary conditions, we show that the lateral\ntension within a circular cone of fixed radius is equal but opposite to the\nradial compression, and independent of the deficit angle itself. We proceed to\nexamine the effect of an oblique outer edge on this cone perturbatively\ndemonstrating that both the correction to the geometry as well as the stress\ndistribution in the cone kicks in at second order in the eccentricity of the\nedge.",
        "positive": "The Role of Chain Entropy in an Analytic Model of Protein Binding in\n  Single-DNA Stretching Experiments: We show that the simple analytical model proposed by Zhang and Marko (Phys.\nRev. E 77, 031916 (2008)) to illustrate Maxwell relations for single-DNA\nexperiments can be improved by including the zero-force entropy of a Gaussian\nchain. The resulting model is in excellent agreement with the discrete\npersistent-chain model and is in a form convenient for analyzing experimental\ndata."
    },
    {
        "anchor": "Analytical coupled vibroacoustic modeling of membrane-type acoustic\n  metamaterials: plate model: By considering the membrane's dissipation, the membrane-type acoustic\nmetamaterial (MAM) has been demonstrated as a super absorber for low-frequency\nsound. In the paper, a theoretical vibroacoustic plate model is developed to\nreveal sound energy absorption mechanism within the MAM under a plane normal\nincidence. Based on the plate model in conjunction with the point matching\nmethod, the in-plane strain energy of the membrane due to the resonant and\nantiresonant motion of the attached masses can be accurately captured by\nsolving the coupled vibroacoustic integrodifferential equation. Therefore, the\nsound absorption of the MAM is obtained and discussed, which is also in good\nagreement with the prediction from the finite element method. In particular,\nmicrostructure effects including eccentricity of the attached masses, the\ndepth, thickness and loss factor of the membrane on sound absorption peak\nvalues are quantitatively investigated.",
        "positive": "Mechanical response of an inclined frictional granular layer approaching\n  unjamming: We present an orthotropic elastic analysis of frictional granular layers\nunder gravity by studying their stress response to a localized overload at the\nlayer surface for several substrate tilt angles. The distance to the unjamming\ntransition is controlled by the tilt angle {\\alpha} with respect to the\ncritical angle \\alpha_c. We find that the shear modulus of the system decreases\nwith {\\alpha}, but reaches a finite value as \\alpha tends to \\alpha_c. We also\nanalyze the vibration modes of the system and show that the soft modes play an\nincreasing, though not crucial, role approaching the transition."
    },
    {
        "anchor": "Is there a Relationship between the Elongational Viscosity and the First\n  Normal Stress Difference in Polymer Solutions?: We investigate a variety of different polymer solutions in shear and\nelongational flow. The shear flow is created in the cone-plate-geometry of a\ncommercial rheometer. We use capillary thinning of a filament that is formed by\na polymer solution in the Capillary Breakup Extensional Rheometer (CaBER) as an\nelongational flow. We compare the relaxation time and the elongational\nviscosity measured in the CaBER with the first normal stress difference and the\nrelaxation time that we measured in our rheometer. All of these four quantities\ndepend on different fluid parameters - the viscosity of the polymer solution,\nthe polymer concentration within the solution, and the molecular weight of the\npolymers - and on the shear rate (in the shear flow measurements).\nNevertheless, we find that the first normal stress coefficient depends\nquadratically on the CaBER relaxation time. A simple model is presented that\nexplains this relation.",
        "positive": "Coherent transport of neutral atoms in spin-dependent optical lattice\n  potentials: We demonstrate the controlled coherent transport and splitting of atomic wave\npackets in spin-dependent optical lattice potentials. Such experiments open\nintriguing possibilities for quantum state engineering of many body states.\nAfter first preparing localized atomic wave functions in an optical lattice\nthrough a Mott insulating phase, we place each atom in a superposition of two\ninternal spin states. Then state selective optical potentials are used to split\nthe wave function of a single atom and transport the corresponding wave packets\nin two opposite directions. Coherence between the wave packets of an atom\ndelocalized over up to 7 lattice sites is demonstrated."
    },
    {
        "anchor": "Classical-path integral adaptive resolution in molecular simulation:\n  towards a smooth quantum-classical coupling: Simulations that couple different classical molecular models in an adaptive\nway by changing the number of degrees of freedom on the fly, are available\nwithin reasonably consistent theoretical frameworks. The same does not occur\nwhen it comes to classical-quantum adaptivity. The main reason for this is the\ndifficulty in describing a continuous transition between the two different kind\nof physical principles: probabilistic for the quantum and deterministic for the\nclassical. Here we report the basic principles of an algorithm that allows for\na continuous and smooth transition by employing the path integral description\nof atoms.",
        "positive": "Why is Understanding Glassy Polymer Mechanics So Difficult?: In this Perspective, I describe recent work on systems in which the\ntraditional distinctions between (i) unentangled vs. well-entangled systems and\n(ii) melts vs. glasses seem least useful, and argue for the broader use in\nglassy polymer mechanics of two more dichotomies: systems which possess (iii)\nunary vs. binary and (iv) cooperative vs. nonccoperative relaxation dynamics. I\ndiscuss the applicability of (iii-iv) to understanding the functional form of\nglassy strain hardening. Results from molecular dynamics simulations show that\nthe \"dramatic\" strain hardening observed in densely entangled systems is\nassociated with a crossover from unary, noncooperative to binary, cooperative\nrelaxation as strain increases; chains stretch between entanglement points,\naltering the character of local plasticity. Promising approaches for future\nresearch along these lines are discussed."
    },
    {
        "anchor": "Enhanced stability of tetratic phase due to clustering: We show that the relative stability of the nematic tetratic phase with\nrespect to the usual uniaxial nematic phase can be greatly enhanced by\nclustering effects. Two--dimensional rectangles of aspect ratio $\\kappa$\ninteracting via hard interactions are considered, and the stability of the two\nnematic phases (uniaxial and tetratic) is examined using an extended\nscaled--particle theory applied to a polydispersed fluid mixture of $n$\nspecies. Here the $i$--th species is associated with clusters of $i$\nrectangles, with clusters defined as stacks of rectangles containing\napproximately parallel rectangles, with frozen internal degrees of freedom. The\ntheory assumes an exponential cluster size distribution (an assumption fully\nsupported by Monte Carlo simulations and by a simple chemical--reaction model),\nwith fixed value of the second moment. The corresponding area distribution\npresents a shoulder, and sometimes even a well-defined peak, at cluster sizes\napproximately corresponding to square shape (i.e. $i\\simeq\\kappa$), meaning\nthat square clusters have a dominant contribution to the free energy of the\nhard--rectangle fluid. The theory predicts an enhanced region of stability of\nthe tetratic phase with respect to the standard scaled--particle theory, much\ncloser to simulation and to experimental results, demonstrating the importance\nof clustering in this fluid.",
        "positive": "Dielectric spectroscopy of ferroelectric nematic liquid crystals:\n  Measuring the capacitance of insulating interfacial layers: Numerous measurements of the dielectric constant $\\epsilon$ of the recently\ndiscovered ferroelectric nematic ($N_F$) liquid crystal (LC) phase report\nextraordinarily large values of $\\epsilon^\\prime$ (up to ~30,000). We show that\nwhat is in fact being measured in such experiments is the high capacitance of\nthe non-ferroelectric, interfacial, insulating layers of nanoscale thickness\nthat bound the $N_F$ material in typical cells.\n  We analyze a parallel-plate cell filled with $N_F$ material of\nhigh-polarization $\\mathbf{P}$, oriented parallel to the plates at zero applied\nvoltage. Minimization of the dominant electrostatic energy renders $\\mathbf{P}$\nspatially uniform and orients it to make the electric field in the $N_F$ as\nsmall as possible, a condition under which the voltage applied to the cell\nappears almost entirely across the high-capacity interfacial layers. This\ncoupling of orientation and charge creates a combined polarization-external\ncapacitance (PCG) Goldstone reorientation mode requiring applied voltages\norders of magnitude smaller than that of the $N_F$ layer alone to effectively\ntransport charge across the $N_F$ layer. The $N_F$ layer acts as a low-value\nresistor and the interfacial capacitors as reversible energy storage\nreservoirs, lowering the restoring force (mass) of the PCG mode and producing\nstrong reactive dielectric behavior. Analysis of data from several experiments\non ferroelectric liquid crystals (chiral smectics C, bent-core smectics, and\nthe $N_F$ phase supports the PCG model, showing that deriving dielectric\nconstants from electrical impedance measurements of high-polarization\nferroelectric LCs, without properly accounting for the self-screening effects\nof polarization charge and the capacitive contributions of interfacial layers,\ncan result in overestimation of the $\\epsilon^\\prime$ values of the LC by many\norders of magnitude."
    },
    {
        "anchor": "Liquid-grain mixing suppresses droplet spreading and splashing during\n  impact: Would a raindrop impacting on a coarse beach behave differently from that\nimpacting on a desert of fine sand? We study this question by a series of model\nexperiments, where the packing density of the granular target, the wettability\nof individual grains, the grain size, the impacting liquid, and the impact\nspeed are varied. We find that by increasing the grain size and/or the\nwettability of individual grains the maximum droplet spreading undergoes a\ntransition from a capillary regime towards a viscous regime, and splashing is\nsuppressed. The liquid-grain mixing is discovered to be the underlying\nmechanism. An effective viscosity is defined accordingly to quantitatively\nexplain the observations.",
        "positive": "Stretching the limits of dynamic and quasi-static flow testing on\n  limestone powders: Powders are a special class of granular matter due to the important role of\ncohesive forces. The flow behavior of powders depends on the flow states and\nstress and is therefore difficult to measure/quantify with only one experiment.\nIn this study, the most commonly used characterization tests that cover a wide\nrange of states are compared: (static, free surface) angle of repose, the\n(quasi-static, confined) ring shear steady state angle of internal friction,\nand the (dynamic, free surface) rotating drum flow angle are considered for\nfree flowing, moderately and strongly cohesive limestone powders. The free\nflowing powder gives good agreement among all different situations (devices),\nwhile the moderately and strongly cohesive powders behave more interestingly.\nStarting from the flow angle in the rotating drum and going slower, one can\nextrapolate to the limit of zero rotation rate, but then observes that the\nangle of repose measured from the heap is considerably larger, possibly due to\nits special history. When we stretch the ring shear test to its lowest\nconfining stress limit, the steady state angle of internal friction of the\ncohesive powder coincides with the flow angle (at free surface) in the zero\nrotation rate limit."
    },
    {
        "anchor": "Saffman-Taylor Fingers at Intermediate Noise: We study Saffman-Taylor flow in the presence of intermediate noise\nnumerically by using both a boundary-integral approach as well as the\nKadanoff-Liang modified Diffusion-Limited Aggregation model that incorporates\nsurface tension and reduced noise. For little to no noise, both models result\nreproduce the well-known Saffman-Taylor finger. We compare both models in the\nregion of intermediate noise where we get occasional tip-splitting events,\nfocusing on the ensemble-average. We show that as the noise in the system is\nincreased, the mean behavior in both models approaches the $\\cos^2(\\pi y/W)$\ntransverse density profile far behind the leading front. We also investigate\nhow the noise scales and affects both models.",
        "positive": "Order Parameter as an Additional State Variable of Unstable Traffic Flow: We discuss a phenomenological approach to the description of unstable vehicle\nmotion on multilane highways that could explain in a simple way such observed\nself-organizing phenomena as the sequence of the phase transitions \"free flow\n-> synchronized motion -> jam\" and the hysteresis in them.\n  We introduce a new variable called order parameter that accounts for possible\ncorrelations in the vehicle motion at different lanes. So, it is principally\ndue to \"many-body\" effects in the car interaction in contrast to such variables\nas the mean car density and velocity being actually the zeroth and first\nmoments of the \"one-particle\" distribution function. Therefore, we regard the\norder parameter as an additional independent state variable of traffic flow and\nformulate the corresponding evolution equation governing the lane changing\nrate.\n  In this context we analyze the instability of homogeneous traffic flow\nmanifesting itself in both of the mentioned above phase transitions where and\nendowing them with the hysteresis. Besides, the jam state is characterized by\nthe vehicle flows at different lanes being independent of one another."
    },
    {
        "anchor": "Elastic moduli fluctuations predict wave attenuation rates in glasses: The disorder-induced attenuation of elastic waves is central to the universal\nlow-temperature properties of glasses. Recent literature offers conflicting\nviews on both the scaling of the wave attenuation rate $\\Gamma(\\omega)$ in the\nlow-frequency limit ($\\omega\\!\\to\\!0$), and on its dependence on glass history\nand properties. A theoretical framework -- termed Fluctuating Elasticity Theory\n(FET) -- predicts low-frequency Rayleigh scattering scaling in $d$ spatial\ndimensions, $\\Gamma(\\omega)\\!\\sim\\!\\gamma\\,\\omega^{d+1}$, where\n$\\gamma\\!=\\!\\gamma(V_{\\rm c})$ quantifies the coarse-grained spatial\nfluctuations of elastic moduli, involving a correlation volume $V_{\\rm c}$ that\nremains debated. Here, using extensive computer simulations, we show that\n$\\Gamma(\\omega)\\!\\sim\\!\\gamma\\,\\omega^3$ is asymptotically satisfied in two\ndimensions ($d\\!=\\!2$) once $\\gamma$ is interpreted in terms of ensemble --\nrather than spatial -- averages, where $V_{\\rm c}$ is replaced by the system\nsize. In so doing, we also establish that the finite-size ensemble-statistics\nof elastic moduli is anomalous and related to the universal $\\omega^4$ density\nof states of soft quasilocalized modes. These results not only strongly support\nFET, but also constitute a strict benchmark for the statistics produced by\ncoarse-graining approaches to the spatial distribution of elastic moduli.",
        "positive": "Effective Interactions and Volume Energies in Charge-Stabilized\n  Colloidal Suspensions: Charge-stabilized colloidal suspensions can be conveniently described by\nformally reducing the macroion-microion mixture to an equivalent one-component\nsystem of pseudo-particles. Within this scheme, the utility of a linear\nresponse approximation for deriving effective interparticle interactions has\nbeen demonstrated [M. J. Grimson and M. Silbert, Mol. Phys. 74, 397 (1991)].\nHere the response approach is extended to suspensions of finite-sized macroions\nand used to derive explicit expressions for (1) an effective electrostatic pair\ninteraction between pseudo-macroions and (2) an associated volume energy that\ncontributes to the total free energy. The derivation recovers precisely the\nform of the DLVO screened-Coulomb effective pair interaction for spherical\nmacroions and makes manifest the important influence of the volume energy on\nthermodynamic properties of deionized suspensions. Excluded volume corrections\nare implicitly incorporated through a natural modification of the inverse\nscreening length. By including nonlinear response of counterions to macroions,\nthe theory may be generalized to systematically investigate effective many-body\ninteractions."
    },
    {
        "anchor": "Hysteretic behavior of a polymer molecule immersed in an incompatible\n  melt: The radius of gyration of a polymer chain immersed in a low molecular weight\nsolvent is known to vary monotonically with the solvent quality. Here, we\nconsider the behavior of a chain immersed in a high molecular weight solvent\n(polymer melt). Unsurprisingly, we find that, as the incompatibility between\nthe chain and the polymer melt is increased, the two limiting conformations of\nthe chain are the ideal random coil (R = aN^1/2) and the dense globule (R =\naN^1/3). We show, however, that between these two limits the radius of gyration\nof the chain presents a hysteretic behavior .",
        "positive": "Role of transverse displacements in the formation of subaqueous barchan\n  dunes: Crescentic shape dunes, known as barchan dunes, are formed by the action of a\nfluid flow on a granular bed. These bedforms are common in many environments,\nexisting under water or in air, and being formed from grains organized in\ndifferent initial arrangements. Although they are frequently found in nature\nand industry, details about their development are still to be understood. In a\nrecent paper [C. A. Alvarez and E. M. Franklin, Phys. Rev. E 96, 062906\n(2017)], we proposed a timescale for the development and equilibrium of single\nbarchans based on the growth of their horns. In the present Letter, we report\nmeasurements of the growth of horns at the grain scale. In our experiments,\nconical heaps were placed in a closed conduit and individual grains were\ntracked as each heap, under the action of a water flow, evolved to a barchan\ndune. We identified the trajectories of the grains that migrated to the growing\nhorns, and found that most of them came from upstream regions on the periphery\nof the initial heap, with an average displacement of the order of the heap\nsize. In addition, we show that individual grains had transverse displacements\nby rolling and sliding that are not negligible, with many of them going around\nthe heap. The mechanism of horns formation revealed by our experiments\ncontrasts with the general picture that barchan horns form from the advance of\nthe lateral dune flanks due to the scaling of migration velocity with the\ninverse of dune size. Our results change the way in which the growth of\nsubaqueous barchan dunes is explained."
    },
    {
        "anchor": "Anomalous behavior of dispersion curves in water-like systems and water: In the present paper we consider dispersion curves of longitudinal\nexcitations of a model core-softened liquid and SPC/E model of water. We show\nthat both systems demonstrate anomalous behavior of the excitation frequencies:\nthe frequencies of the excitations can decrease with temperature along\nisochors, while in normal liquids they should increase. This observation allows\nto introduce one more water anomaly - anomalous dependence of excitation\nfrequencies on temperature.",
        "positive": "Bragg spectroscopy of discrete axial quasiparticle modes in a\n  cigar-shaped degenerate Bose gas: We propose an experiment in which long wavelength discrete axial\nquasiparticle modes can be imprinted in a 3D cigar-shaped Bose-Einstein\ncondensate by using two-photon Bragg scattering experiments, similar to the\nexperiment at the Weizmann Institute [J. Steinhauer {\\em et al.}, Phys. Rev.\nLett. {\\bf 90}, 060404 (2003)] where short wavelength axial phonons with\ndifferent number of radial modes have been observed. We provide values of the\nmomentum, energy and time duration of the two-photon Bragg pulse and also the\ntwo-body interaction strength which are needed in the Bragg scattering\nexperiments in order to observe the long wavelength discrete axial modes. These\ndiscrete axial modes can be observed when the system is dilute and the time\nduration of the Bragg pulse is long enough."
    },
    {
        "anchor": "Simple model squirmers with tunable velocity: We present a scheme of self-propelling liquid droplets which closely mimics\nthe locomotion of some protozoal organisms, so-called squirmers. In contrast to\nother schemes proposed earlier, locomotion paths are not self-avoiding, since\nthe effect of the squirmer on the surrounding medium is weak. Our results\nsuggest that not only the velocity, but also the mode of operation (i.e., the\nspherical harmonics of the flow field) can be controlled by appropriate\nvariation of parameters.",
        "positive": "Simulating liquid-vapor phase separation under shear with lattice\n  Boltzmann method: We study liquid-vapor phase separation under shear via the Shan-Chen lattice\nBoltzmann model. Besides the rheological characteristics, we analyze the\nKelvin-Helmholtz(K-H) instability resulting from the tangential velocity\ndifference of the fluids on two sides of the interface. We discuss also the\ngrowth behavior of droplets. The domains being close to the walls are\nlamellar-ordered, where the hydrodynamic effects dominate. The patterns in the\nbulk of the system are nearly isotropic, where the domain growth results mainly\nfrom the diffusion mechanism. Both the interfacial tension and the K-H\ninstability make the liquid-bands near the walls tend to rupture. When the\nshear rate increases, the inequivalence of evaporation in the upstream and\ncoagulation in the downstream of the flow as well as the role of surface\ntension makes the droplets elongate obliquely. Stronger convection makes easier\nthe transferring of material particles so that droplets become larger."
    },
    {
        "anchor": "Active colloidal chains with cilia- and flagella-like motion: It has been shown that self-assembled chains of active colloidal particles\ncan present sustained oscillations. These oscillations are possible because of\nthe effective diffusiophoretic forces that mediate the interactions of colloids\ndo not respect the action--reaction principle and hence, a Hopf bifurcation is\npossible even for overdamped dynamics. Anchoring the particles in one extreme\nbreaks the head-tail symmetry and the oscillation is transformed into a\ntraveling wave pattern and thus the chain behaves like a beating cilium. The\nnet force on the anchor, estimated using the resistive force theory, vanishes\nbefore the bifurcation and thereafter grows linearly with the bifurcation\nparameter. If the mobilities of the particles on one extreme are reduced to\nmimic an elongated cargo, the traveling wave generates a net velocity on the\nchain that now behaves like a moving flagellum. The average velocity again\ngrows linearly with the bifurcation parameter. Our results demonstrate that\nsimplified systems, consisting only of a few particles with non-reciprocal\ninteraction and head-tail asymmetry show beating motion and self-propulsion.\nBoth properties are present in many non-equilibrium models thus making our\nresults a general feature of active matter.",
        "positive": "Chiral symmetry-breaking dynamics in the phase transformation of nematic\n  droplets: Dynamic simulations of the isotropic-nematic phase transformation of liquid\ncrystal droplets under homeotropic anchoring are found to predict chiral\nsymmetry-breaking dynamics. These observations occur when using material\nparameters for pentyl-cyanobiphenyl (5CB) but not under the single elastic\nconstant approximation of this material, frequently used in simulation. The\ntwisting dynamic process occurs during the relaxation of the domain from an\nunstable radial texture to a stable uniform texture and involves simultaneous\ndefect loop motion and twisting of the bulk nematic texture."
    },
    {
        "anchor": "Influence of solvent granularity on the effective interaction between\n  charged colloidal suspensions: We study the effect of solvent granularity on the effective force between two\ncharged colloidal particles by computer simulations of the primitive model of\nstrongly asymmetric electrolytes with an explicitly added hard sphere solvent.\nApart from molecular oscillating forces for nearly touching colloids which\narise from solvent and counterion layering, the counterions are attracted\ntowards the colloidal surfaces by solvent depletion providing a simple\nstatistical description of hydration. This, in turn, has an important influence\non the effective forces for larger distances which are considerably reduced as\ncompared to the prediction based on the primitive model. When these forces are\nrepulsive, the long-distance behaviour can be described by an effective Yukawa\npair potential with a solvent-renormalized charge. As a function of colloidal\nvolume fraction and added salt concentration, this solvent-renormalized charge\nbehaves qualitatively similar to that obtained via the Poisson-Boltzmann cell\nmodel but there are quantitative differences. For divalent counterions and\nnano-sized colloids, on the other hand, the hydration may lead to overscreened\ncolloids with mutual attraction while the primitive model yields repulsive\nforces. All these new effects can be accounted for through a solvent-averaged\nprimitive model (SPM) which is obtained from the full model by integrating out\nthe solvent degrees of freedom. The SPM was used to access larger colloidal\nparticles without simulating the solvent explicitly.",
        "positive": "Castaing Instability and Precessing Domains in Confined Alkali Gases: We explore analogy between two-component quantum alkali gases and\nspin-polarized helium systems. Recent experiments in trapped gases are put into\nthe frame of the existing theory for Castaing instability in transverse channel\nand formation of homogeneous precessing domains in spin-polarized systems.\nAnalogous effects have already been observed in spin-polarized $% ^{3}He$ and\n$^{3}He- ^{4}He$ mixtures systems. The threshold effect of the confining\npotential on the instability is analyzed. New experimental possibilities for\nobservation of transverse instability in a trap are discussed."
    },
    {
        "anchor": "A model for the onset of oscillations near the stopping angle in an\n  inclined granular flow: We propose an explanation for the onset of oscillations seen in numerical\nsimulations of dense, inclined flows of inelastic, frictional spheres. It is\nbased on a phase transition between disordered and ordered collisional states\nthat may be interrupted by the formation of force chains. Low frequency\noscillations between ordered and disordered states take place over weakly bumpy\nbases; higher-frequency oscillations over strongly bumpy bases involve the\nformation of particle chains that extend to the base and interrupt the phase\nchange. The predicted frequency and amplitude of the oscillations induced by\nthe unstable part of the equation of state are similar to those seen in the\nsimulations and they depend upon the contact stiffness in the same way. Such\noscillations could be the source of sound produced by flowing sand.",
        "positive": "Smoothening Transition of Rough Surfactant Surfaces: We propose a model for surfaces in mixtures of oil, water and surfactants\nwith strong electric dipoles. The dipole interactions give rise to a non-local\ninteraction with negative stiffness between surface elements. We show that, for\nlarge space dimension D, this model has a phase transition from rough to smooth\nsurfaces. Contrary to models with a simple quadratic curvature energy of\npositive sign, which always have a finite persistence length typical of rough\nsurfaces, the smooth surfaces in our model exhibit long-range correlations of a\ngeneralized antiferromagnetic type. These correlations might be related to the\nrecently observed \"egg carton\" superstructure of membranes."
    },
    {
        "anchor": "Thermodynamics of nano-spheres encapsulated in virus capsids: We investigate the thermodynamics of complexation of functionalized charged\nnano-spheres with viral proteins. The physics of this problem is governed by\nelectrostatic interaction between the proteins and the nano-sphere cores\n(screened by salt ions), but also by configurational degrees of freedom of the\ncharged protein N-tails. We approach the problem by constructing an appropriate\ncomplexation free energy functional. On the basis of both numerical and\nanalytical studies of this functional we construct the phase diagram for the\nassembly which contains the information on the assembled structures that appear\nin the thermodynamical equilibrium, depending on the size and surface charge\ndensity of the nano-sphere cores. We show that both the nano-sphere core charge\nas well as its radius determine the size of the capsid that forms around the\ncore.",
        "positive": "Mobility of nanometer-size solutes in water driven by electric field: We investigate the mobility of nanometer-size solutes in water in a uniform\nexternal electric field. General arguments are presented to show that a closed\nsurface cutting a volume from a polar liquid will carry an effective non-zero\nsurface charge density when preferential orientation of dipoles exists in the\ninterface. This effective charge will experience a non-vanishing drag in an\nexternal electric field even in the absence of free charge carriers. Numerical\nsimulations of model solutes are used to estimate the magnitude of the surface\ncharge density. We find it to be comparable to the values typically reported\nfrom the mobility measurements. Hydrated ions can potentially carry a\nsignificant excess of the effective charge due to over-polarization of the\ninterface. As a result, the electrokinetic charge can significantly deviate\nfrom the physical charge of free charge carriers. We propose to test the model\nby manipulating the polarizability of hydrated semiconductor nanoparticles with\nlight. The inversion of the mobility direction can be achieved by\nphotoexcitation, which increases the nanoparticle polarizability and leads to\nan inversion of the dipolar orientations of water molecules in the interface."
    },
    {
        "anchor": "Hexatic phase in the two-dimensional Gaussian-core model: We present a Monte Carlo simulation study of the phase behavior of\ntwo-dimensional classical particles repelling each other through an isotropic\nGaussian potential. As in the analogous three-dimensional case, a\nreentrant-melting transition occurs upon compression for not too high\ntemperatures, along with a spectrum of water-like anomalies in the fluid phase.\nHowever, in two dimensions melting is a continuous two-stage transition, with\nan intermediate hexatic phase which becomes increasingly more definite as\npressure grows. All available evidence supports the\nKosterlitz-Thouless-Halperin-Nelson-Young scenario for this melting transition.\nWe expect that such a phenomenology can be checked in confined monolayers of\ncharge-stabilized colloids with a softened core.",
        "positive": "A microfluidic device for investigating crystal nucleation kinetics: We have developed an original setup using microfluidic tools allowing one to\nproduce continuously monodisperse microreactors ($\\approx 100$ nL), and to\ncontrol their temperatures as they flow in the microdevice. With a specific\nmicrochannels geometry, we are able to apply large temperature quenches to\ndroplets containing a KNO$_3$ solution (up to 50$^{\\circ}$C in 10 s), and then\nto follow nucleation kinetics at high supersaturations. By measuring the\nprobability of crystal presence in the droplets as a function of time, we\nestimate the nucleation rate for different supersaturations, and confront our\nresults to the classical nucleation theory."
    },
    {
        "anchor": "Manipulating the Speed of Sound in a Two-Component Bose-Einstein\n  Condensate: We consider a two-component weakly interacting Bose-Einstein condensate in\nthe presence of an external field which couples the two components. We express\nthe Hamiltonian in terms of the energy eigenstates of the single-body part of\nthe Hamiltonian. These eigenstates are the atomic dressed states of quantum\noptics. When the energy difference between the two dressed states is much\nlarger than the mean-field interactions, two-body interactions in the dressed\nstate basis that do not conserve the number of atoms in each of the two dressed\nstates are highly suppressed. The two-body interactions then take on a\nsimplified form in the dressed basis with effective coupling constants that\ndepend on the intensity and frequency of the external field. This implies that\nthe chemical potential as well as the quasiparticle spectrum may be controlled\nexperimentally in a simple manner. We demonstrate this by showing that one may\nachieve significant variations in the speed of sound in the condensate, a\nquantity which has been measured experimentally.",
        "positive": "Phase separation kinetics of segregating fluid mixtures in the presence\n  of quenched disorder: Quenched or frozen-in structural disorder is ubiquitous in real experimental\nsystems. Much of the progress is achieved in understanding the phase separation\nof such systems using the diffusion-driven coarsening in Ising model with\nquenched disorder. But there is a paucity of research in the phase separation\nkinetics in fluids with quenched disorder. In this paper, we present results\nfrom a detailed Molecular dynamics simulation, the effects of randomly placed\nlocalized impurities on the phase separating kinetics of binary fluid mixture.\nTwo different models are offered for representing the impurities. We observe a\ndramatic slowing down in the pattern formation with increasing impurity\nconcentration. This sluggish domain growth kinetics follows power-law with a\ndisorder-dependent exponent. The correlation function and structure factor show\na non-Porod behavior, indicating the roughening of domain interfaces. We have\nalso studied the effect of quenched disorder on the aging dynamics by\ncalculating the two-time order parameter auto correlation function and find\nthat the Fisher and Huse scaling law holds good in presence of quenched\ndisorder."
    },
    {
        "anchor": "Minimum Surfactant Concentration Required for Inducing Self-shaping of\n  Oil Droplets and Competitive Adsorption Effects: Surfactant choice is key in starting the phenomena of artificial\nmorphogenesis, the bottom-up growth of geometric particles from cooled emulsion\ndroplets, as well as the bottom-up self-assembly of rechargeable microswimmer\nrobots from similar droplets. The choice of surfactant is crucial for the\nformation of a plastic phase at the oil-water interface, for the kinetics, and\nfor the onset temperature of these processes. But further details are needed to\ncontrol these processes for bottom-up manufacturing and understand their\nmolecular mechanisms. Still unknown are the minimum concentration of the\nsurfactant necessary to induce the processes, or competing effects in a mixture\nof surfactants when only one is capable of inducing shapes. Here we\nsystematically study the effect of surfactant nature and concentration on the\nshape-inducing behaviour of hexadecane-in-water emulsions with both cationic\n(CTAB) and non-ionic (Tween, Brij) surfactants over up to five orders of\nmagnitude of concentration. The minimum effective concentration is found\napproximately equal to the critical micelle concentration (CMC), or the\nsolubility limit below the Krafft point of the surfactant. However, the\nemulsions show low stability at the vicinity of CMC. In a mixed surfactant\nexperiment (Tween 60 and Tween 20), where only one (Tween 60) can induce shapes\nwe elucidate the role of competition at the interface during mixed surfactant\nadsorption by varying the composition. We find that a lower bound of ~ 75%\nsurface coverage of the shape-inducing surfactant with C14 or longer chain\nlength is necessary for self-shaping to occur. The resulting technique produces\na clear visual readout of otherwise difficult to investigate molecular events\nand establish basic requirements for minimum concentration and protocols to\nfind % surface coverage to induce oil self-shaping by surfactant mixtures.",
        "positive": "Size and density avalanche scaling near jamming: The current microscopic picture of plasticity in amorphous materials assumes\nlocal failure events to produce displacement fields complying with linear\nelasticity. Indeed, the flow properties of nonaffine systems such as foams,\nemulsions and granular materials close to jamming, that produce a fluctuating\ndisplacement fields when failing, are still controversial. Here we show, via a\nthorough numerical investigation of jammed materials, that nonaffinity induces\na critical scaling of the flow properties dictated by the distance to the\njamming point. We rationalize this critical behavior introducing a new\nuniversal jamming exponent and hyperscaling relations, and use these results to\ndescribe the volume fraction dependence of the friction coefficient."
    },
    {
        "anchor": "Density-functional study of defects in two-dimensional circular nematic\n  nanocavities: We use density--functional theory to study the structure of two-dimensional\ndefects inside a circular nematic nanocavity. The density, nematic order\nparameter, and director fields, as well as the defect core energy and core\nradius, are obtained in a thermodynamically consistent way for defects with\ntopological charge $k=+1$ (with radial and tangential symmetries) and $k=+1/2$.\nAn independent calculation of the fluid elastic constants, within the same\ntheory, allows us to connect with the local free--energy density predicted by\nelastic theory, which in turn provides a criterion to define a defect core\nboundary and a defect core free energy for the two types of defects. The radial\nand tangential defects turn out to have very different properties, a feature\nthat a previous Maier--Saupe theory could not account for due to the simplified\nnature of the interactions --which caused all elastic constants to be equal. In\nthe case with two $k=+1/2$ defects in the cavity, the elastic r\\'egime cannot\nbe reached due to the small radii of the cavities considered, but some trends\ncan already be obtained.",
        "positive": "Shapes of fluid membranes with chiral edges: We carry out Monte Carlo simulations of a colloidal fluid membrane composed\nof chiral rod-like viruses. The membrane is modeled by a triangular mesh of\nbeads connected by bonds in which the bonds and beads are free to move at each\nMonte Carlo step. Since the constituent viruses are experimentally observed to\ntwist only near the membrane edge, we use an effective energy that favors a\nparticular sign of the geodesic torsion of the edge. The effective energy also\nincludes membrane bending stiffness, edge bending stiffness, and edge tension.\nWe find three classes of membrane shapes resulting from the competition of the\nvarious terms in the free energy: branched shapes, chiral disks, and vesicles.\nIncreasing the edge bending stiffness smooths the membrane edge, leading to\ncorrelations among the membrane normal at different points along the edge. We\nalso consider membrane shapes under an external force by fixing the distance\nbetween two ends of the membrane, and find the shape for increasing values of\nthe distance between the two ends. As the distance increases, the membrane\ntwists into a ribbon, with the force eventually reaching a plateau."
    },
    {
        "anchor": "A direct link between active matter and sheared granular systems: The similarity in mechanical properties of dense active matter and sheared\namorphous solids has been noted in recent years without a rigorous examination\nof the underlying mechanism. We develop a mean-field model that predicts that\ntheir critical behavior should be equivalent in infinite dimensions, up to a\nrescaling factor that depends on the correlation length of the applied field.\nWe test these predictions in 2d using a new numerical protocol, termed\n`athermal quasi-static random displacement', and find that these mean-field\npredictions are surprisingly accurate in low dimensions. We identify a general\nclass of perturbations that smoothly interpolate between the uncorrelated\nlocalized forces that occur in the high-persistence limit of dense active\nmatter, and system-spanning correlated displacements that occur under applied\nshear. These results suggest a universal framework for predicting flow,\ndeformation, and failure in active and sheared disordered materials.",
        "positive": "Localization of Excitons by Molecular Layer Formation in a Polymer Film: Atactic polystyrene of two different molecular weights (560900 g.mol-1 and\n212400 g.mol-1) have been studied as spin-coated films of thickness varying\nfrom ~30 nm to ~250 nm, i.e., ~2Rg to ~12Rg where Rg is the unperturbed radius\nof gyration of polystyrene, using x-ray reflectivity and transmission\nUV-spectroscopy. Electron density profiles along depth of the films show\nformation of layers parallel to the substrate surface, when the film thickness\nis below 4Rg, with layer spacing ~2Rg. The pure electronic singlet 1A1g -> 1E1u\nindicates exciton interaction throughout film thickness, as evidenced by the\nlineshape, drop in extinction coefficient and size-dependent blue shift of the\ncorresponding UV peak. Analysis of the total energy of the exciton as a\nfunction of film thickness shows that above the thickness of 4Rg the exciton is\ndelocalized over the film thickness through linear, molecular J-aggregates. The\nseparations between these molecules in the two polystyrene samples match with\nthe respective layer spacing obtained from x-ray reflectivity. Transition\ndipole moments of the molecules in this aggregate are parallel and each dipole\nis arranged at an angle of ~43 degrees with the axis of the linear chain. Below\na film thickness of 4Rg, as the molecular layers are formed, the exciton\nbecomes localized within these layers. This localization is clearly indicated\nby the lineshape becoming comparable to isolated molecular bands, and by both\nthe extinction coefficient and blue shift reaching maximum values and becoming\nsize independent. Localization of excitons due to layer formation has been\nexplained as caused by decrease of cohesion between layers."
    },
    {
        "anchor": "Large-Scale Simulations of Diffusion-Limited n-Species Annihilation: We present results from computer simulations for diffusion-limited\n$n$-species annihilation, $A_i+A_j\\to0$ $(i,j=1,2,...,n;i\\neq j)$, on the line,\nfor lattices of up to $2^{28}$ sites, and where the process proceeds to\ncompletion (no further reactions possible), involving up to $10^{15}$ time\nsteps. These enormous simulations are made possible by the renormalized\nreaction-cell method (RRC). Our results suggest that the concentration decay\nexponent for $n$ species is $\\a(n)=(n-1)/2n$ instead of $(2n-3)/(4n-4)$, as\npreviously believed, and are in agreement with recent theoretical arguments\n\\cite{tauber}. We also propose a scaling relation for $\\Delta$, the\ncorrection-to-scaling exponent for the concentration decay; $c(t)\\sim\nt^{-\\a}(A+Bt^{-\\Delta})$.",
        "positive": "Collective Vortical Motion and Vorticity Reversals of Self-Propelled\n  Particles on Circularly Patterned Substrates: The collective behavior of self-propelled particles (SPPs) under the combined\neffects of a circularly patterned substrate and circular confinement is\ninvestigated through coarse-grained molecular dynamics simulations of polarized\nand disjoint ring polymers. The study is performed over a wide range of values\nof the SPPs packing fraction $\\bar\\phi$, motility force $F_D$, and area\nfraction of the patterned region. At low packing fractions, the SPPs are\nexcluded from the system's center and exhibit a vortical motion that is\ndominated by the substrate at intermediate values of $F_D$. This exclusion zone\nis due to the coupling between the driving force and torque induced by the\nsubstrate, which induces an outward spiral motion of the SPPs. For high values\nof $F_D$, the SPPs exclusion from the center is dominated by the confining\nboundary. At high values of $\\bar\\phi$, the substrate pattern leads to\nreversals in the vorticity, which become quasi-periodic with increasing\n$\\bar\\phi$. We also found that the substrate pattern is able to separate SPPs\nbased on their motilities."
    },
    {
        "anchor": "Water skin anomalies: density, elasticity, hydrophobicity, thermal\n  stability, interface repulsivity, etc: Molecular undercoordination induced O:H-O bond relaxation and dual\npolarization dictates the supersolid behavior of water skins interacting with\nother substances such as flowing in nanochannels, dancing of water droplets,\nfloating of insects. The BOLS-NEP notion unifies the Wenzel-Cassie-Baxter\nmodels and explains controllable transition between hydrophobicity and\nhydrophilicity.",
        "positive": "Intermediate scattering function of an anisotropic active Brownian\n  particle: Various challenges are faced when animalcules such as bacteria, protozoa,\nalgae, or sperms move autonomously in aqueous media at low Reynolds number.\nThese active agents are subject to strong stochastic fluctuations, that compete\nwith the directed motion. So far most studies consider the lowest order moments\nof the displacements only, while more general spatio-temporal information on\nthe stochastic motion is provided in scattering experiments. Here we derive\nanalytically exact expressions for the directly measurable intermediate\nscattering function for a mesoscopic model of a single, anisotropic active\nBrownian particle in three dimensions. The mean-square displacement and the\nnon-Gaussian parameter of the stochastic process are obtained as derivatives of\nthe intermediate scattering function. These display different temporal regimes\ndominated by effective diffusion and directed motion due to the interplay of\ntranslational and rotational diffusion which is rationalized within the theory.\nThe most prominent feature of the intermediate scattering function is an\noscillatory behavior at intermediate wavenumbers reflecting the persistent\nswimming motion, whereas at small length scales bare translational and at large\nlength scales an enhanced effective diffusion emerges. We anticipate that our\ncharacterization of the motion of active agents will serve as a reference for\nmore realistic models and experimental observations."
    },
    {
        "anchor": "Phase separation of a model binary polymer solution in an external field: The phase separation of a simple binary mixture of incompatible linear\npolymers in solution is investigated using an extension of the sedimentation\nequilibrium method, whereby the osmotic pressure of the mixture is extracted\nfrom the density profiles of the inhomogeneous mixture in a gravitational\nfield. In Monte-Carlo simulations the field can be tuned to induce significant\ninhomogeneity, while keeping the density profiles sufficiently smooth for the\nmacroscopic condition of hydrostatic equilibrium to remain applicable. The\nmethod is applied here for a simplified model of ideal, but mutually avoiding\npolymers, which readily phase separate at relatively low densities. The\nMonte-Carlo data are interpreted with the help of an approximate bulk phase\ndiagram calculated from a simple, second order virial coefficient theory. By\nderiving effective potentials between polymer centres of mass, the binary\nmixture of polymers is coarse-grained to a ``soft colloid'' picture reminiscent\nof the Widom-Rowlinson model for incompatible atomic mixtures. This approach\nsignificantly speeds up the simulations, and accurately reproduces the\nbehaviour of the full monomer resolved model.",
        "positive": "Water-like anomalies for core-softened models of fluids: One dimension: We use a one-dimensional (1d) core-softened potential to develop a physical\npicture for some of the anomalies present in liquid water. The core-softened\npotential mimics the effect of hydrogen bonding. The interest in the 1d system\nstems from the facts that closed-form results are possible and that the\nqualitative behavior in 1d is reproduced in the liquid phase for higher\ndimensions. We discuss the relation between the shape of the potential and the\ndensity anomaly, and we study the entropy anomaly resulting from the density\nanomaly. We find that certain forms of the two-step square well potential lead\nto the existence at T=0 of a low-density phase favored at low pressures and of\na high-density phase favored at high pressures, and to the appearance of a\npoint $C'$ at a positive pressure, which is the analog of the T=0 ``critical\npoint'' in the $1d$ Ising model. The existence of point $C'$ leads to anomalous\nbehavior of the isothermal compressibility $K_T$ and the isobaric specific heat\n$C_P$."
    },
    {
        "anchor": "Vibrational lifetimes and viscoelastic properties of ultrastable glasses: Amorphous solids are viscoelastic. They dissipate energy when deformed at\nfinite rate and finite temperature. We here use analytic theory and molecular\nsimulations to demonstrate that linear viscoelastic dissipation can be directly\nrelated to the static and dynamic properties of the fundamental vibrational\nexcitations of an amorphous system. We study ultrastable glasses that do not\nage, i.e. that remain in stable minima of the potential energy surface at\nfinite temperature. Our simulations show four types of vibrational modes, which\ndiffer in spatial localization, similarity to plane waves and vibrational\nlifetimes. At frequencies below the Boson peak, the viscoelastic response can\nbe split into contributions from plane-wave and quasilocalized modes. We derive\na parameter-free expression for the viscoelastic storage and loss moduli for\nboth of these modes. Our results show that the dynamics of microscopic\ndissipation, in particular the lifetimes of the modes, determine the\nviscoelastic response only at high frequency. Quasilocalized modes dominate the\nlinear viscoelastic response at intermediate frequencies below the Boson peak.",
        "positive": "Strong Localization of Positive Charge in DNA: Microscopic mechanisms of positive charge transfer in DNA remain unclear. A\nquantum state of electron hole in DNA is determined by the competition of a\npi-stacking interaction $b$ smearing a charge between different base pairs and\ninteraction $\\lambda$ with the local environment which attempts to trap charge.\nTo determine which interaction dominates we investigated charge quantum states\nin various $(GC)_{n}$ sequences choosing DNA parameters satisfying experimental\ndata for the balance of charge transfer rates $G^{+} \\leftrightarrow\nG_{n}^{+}$, $n=2,3$ \\cite{FredMain}. We show that experimental data can be\nconsistent with theory only under an assumption $b\\ll \\lambda$ meaning that\ncharge is typically localized within a single $G$ site. Consequently any DNA\nsequence including the one consisting of identical base pairs behaves more like\nan insulating material than a molecular conductor."
    },
    {
        "anchor": "Water Evaporation: A Transition Path Sampling Study: We use transition path sampling to study evaporation in the SPC/E model of\nliquid water. Based on thousands of evaporation trajectories, we characterize\nthe members of the transition state ensemble (TSE), which exhibit a\nliquid-vapor interface with predominantly negative mean curvature at the site\nof evaporation. We also find that after evaporation is complete, the\ndistributions of translational and angular momenta of the evaporated water are\nMaxwellian with a temperature equal to that of the liquid. To characterize the\nevaporation trajectories in their entirety, we find that it suffices to project\nthem onto just two coordinates: the distance of the evaporating molecule to the\ninstantaneous liquid-vapor interface, and the velocity of the water along the\naverage interface normal. In this projected space, we find that the TSE is\nwell-captured by a simple model of ballistic escape from a deep potential well,\nwith no additional barrier to evaporation beyond the cohesive strength of the\nliquid. Equivalently, they are consistent with a near-unity probability for a\nwater molecule impinging upon a liquid droplet to condense. These results agree\nwith previous simulations and with some, but not all, recent experiments.",
        "positive": "A Discotic Disguised as a Smectic: A Hybrid Columnar Bragg Glass: We show that discotics, lying deep in the columnar phase, can exhibit an\nx-ray scattering pattern which mimics that of a somewhat unusual smectic liquid\ncrystal. This exotic, new glassy phase of columnar liquid crystals, which we\ncall a ``hybrid columnar Bragg glass'', can be achieved by confining a columnar\nliquid crystal in an anisotropic random environment of e.g., strained aerogel.\nLong-ranged orientational order in this phase makes {\\em single domain} x-ray\nscattering possible, from which a wealth of information could be extracted. We\ngive detailed quantitative predictions for the scattering pattern in addition\nto exponents characterizing anomalous elasticity of the system."
    },
    {
        "anchor": "Self-assembled structures of colloidal dimers and disks on a spherical\n  surface: We study the self-assembly on a spherical surface of a model for a binary\nmixture of amphiphilic dimers in the presence of guest particles via Monte\nCarlo (MC) computer simulation. All particles have a hard core, but one monomer\nof the dimer also interacts with the guest particle by means of a short-range\nattractive potential. We observe the formation of aggregates of various shape\nas a function of the composition of the mixture and of the size of guest\nparticles. Our MC simulations are a further step towards a microscopic\nunderstanding of experiments on colloidal aggregation over curved surfaces,\nsuch as oil droplets.",
        "positive": "Extracting the properties of quasilocalized modes in computer glasses:\n  Long-range continuum fields, contour integrals and boundary effects: Low-frequency nonphononic modes and plastic rearrangements in glasses are\nspatially quasilocalized, i.e. feature a disorder-induced short-range core and\nknown long-range decaying elastic fields. Extracting the unknown short-range\ncore properties, potentially accessible in computer glasses, is of prime\nimportance. Here we consider a class of contour integrals, performed over the\nknown long-range fields, which are especially designed for extracting the core\nproperties. We first show that in computer glasses of typical sizes used in\ncurrent studies, the long-range fields of quasilocalized modes experience\nboundary effects related to the simulation box shape and the widely employed\nperiodic boundary conditions. In particular, image interactions mediated by the\nbox shape and the periodic boundary conditions induce fields' rotation and\norientation-dependent suppression of their long-range decay. We then develop a\ncontinuum theory that quantitatively predicts these finite-size boundary\neffects and support it by extensive computer simulations. The theory accounts\nfor the finite-size boundary effects and at the same time allows the extraction\nof the short-range core properties, such as their typical strain ratios and\norientation. The theory is extensively validated in both 2D and 3D. Overall,\nour results offer a useful tool for extracting the intrinsic core properties of\nnonphononic modes and plastic rearrangements in computer glasses."
    },
    {
        "anchor": "Equation-free dynamic renormalization in a glassy compaction model: Combining dynamic renormalization with equation-free computational tools, we\nstudy the apparently self-similar evolution of void distribution dynamics in\nthe diffusion-deposition problem proposed by Stinchcombe and Depken [Phys. Rev.\nLett. 88, 125701 (2002)]. We illustrate fixed point and dynamic approaches,\nforward as well as backward in time.",
        "positive": "Onset of turbulence in superfluid 3He-B and its dependence on vortex\n  injection in applied flow: Vortex dynamics in 3He-B is divided by the temperature dependent damping into\na high-temperature regime, where the number of vortices is conserved, and a\nlow-temperature regime, where rapid vortex multiplication takes place in a\nturbulent burst. We investigate experimentally the hydrodynamic transition\nbetween these two regimes by injecting seed vortex loops into vortex-free\nrotating flow. The onset temperature of turbulence is dominated by the roughly\nexponential temperature dependence of vortex friction, but its exact value is\nfound to depend on the injection method."
    },
    {
        "anchor": "Spherical nematics with a threefold valence: We present a theoretical study of the energetics of thin nematic shells with\ntwo charge one-half defects and one charge-one defect. We determine the optimal\narrangement: the defects are located on a great circle at the vertices of an\nisosceles triangle with angles of 66 degrees at the charge one-half defects and\na distinct angle of 48 degrees, consistent with experimental findings. We also\nanalyse thermal fluctuations around this ground state and estimate the energy\nas a function of thickness. We find that the energy of the three-defect shell\nis close to the energy of other known configurations having two charge-one and\nfour charge one-half defects. This finding, together with the large energy\nbarriers separating one configuration from the others, explains their\nobservation in experiments as well as their long-time stability.",
        "positive": "Simple lattice model for biological gels: We construct a three-dimensional lattice model for biological gels in which\nstraight lines of bonds correspond to filamentous semi-flexible polymers and\nlattice sites, which are exactly four-fold coordinated, to crosslinks. With\nonly stretching central forces between nearest neighbors, this lattice is\nsub-isostatic with an extensive number of zero modes; but all of its elastic\nconstants are nonzero, and its elastic response is affine. Removal of bonds\nwith probability $1-p$ leads to a lattice with average coordination number less\nthan four and a distribution of polymer lengths. When bending forces are added,\nthe diluted lattice exhibits a rigidity threshold at $p=p_b<1$ and crossover\nfrom bending-dominated nonaffine to stretching-dominated affine response\nbetween $p_b$ and $p=1$."
    },
    {
        "anchor": "Adhesion Induced DNA Naturation: DNA adsorption and naturation is modeled via two interacting flexible\nhomopolymers coupled to a solid surface. DNA denatures if the entropy gain for\nunbinding the two strands overcomes the loss of binding energy. When adsorbed\nto a surface, the entropy gain is smaller than in the bulk, leading to a\nstronger binding and, upon neglecting self-avoidance, absence of a denatured\nphase. Now consider conditions where the binding potentials are too weak for\nnaturation, and the surface potential too weak to adsorb single strands. In a\nvariational approach it is shown that their combined action may lead to a\nnaturated adsorbed phase. Conditions for the absence of naturation and\nadsorption are derived too. The phase diagram is constructed qualitatively.",
        "positive": "CARS polarized microscopy of three-dimensional director structures in\n  liquid crystals: We demonstrate three-dimensional vibrational imaging of director structures\nin liquid crystals using coherent anti-Stokes Raman scattering (CARS) polarized\nmicroscopy. Spatial mapping of the structures is based on sensitivity of a\npolarized CARS signal to orientation of anisotropic molecules in liquid\ncrystals. As an example, we study structures in a smectic material and\ndemonstrate that single-scan CARS and two-photon fluorescence images of\nmolecular orientation patterns are consistent with each other and with the\nstructure model."
    },
    {
        "anchor": "Self-assembly of lipids in water. Exact results from a one-dimensional\n  lattice model: We consider a lattice model for amphiphiles in a solvent with molecules\nchemically similar to one part of the amphiphilic molecule. The dependence of\nthe interaction potential on orientation of the amphiphilic molecules is taken\ninto account explicitly. The model is solved exactly in one dimension by the\ntransfer-matrix method. In particular, pressure as a function of concentration,\ncorrelation function and specific heat are calculated. The model is compared\nwith the recently introduced lattice model for colloidal self-assembly, where\nthe particles interact with the isotropic short-range attraction and long-range\nrepulsion (SALR) potential. Similarities between the amphiphilic and the\ncolloidal self-assembly are highlighted.",
        "positive": "Single polymer adsorption in shear: flattening versus hydrodynamic lift\n  and corrugation effects: The adsorption of a single polymer to a flat surface in shear is investigated\nusing Brownian hydrodynamics simulations and scaling arguments. Competing\neffects are disentangled: in the absence of hydrodynamic interactions, shear\ndrag flattens the chain and thus enhances adsorption. Hydrodynamic lift on the\nother hand gives rise to long-ranged repulsion from the surface which preempts\nthe surface-adsorbed state via a discontinuous desorption transition, in\nagreement with theoretical arguments. Chain flattening is dominated by\nhydrodynamic lift, so overall, shear flow weakens the adsorption of flexible\npolymers. Surface friction due to small-wavelength surface potential\ncorrugations is argued to weaken the surface attraction as well."
    },
    {
        "anchor": "The cage effect in systems of hard spheres: The cage effect is generally invoked when discussing the delay in the decay\nof time correlation functions of dense fluids. In an attempt to examine the\nrole of caging more closely we consider the spread of the displacement\ndistributions of Brownian particles. These distributions are necessarily biased\nby the presence of neighbouring particles. Accommodation of this bias by those\nneighbours conserves the displacement distribution locally and presents a\ncollective mechanism for exploring configuration space that is more efficient\nthan the intrinsic Brownian motion. Caging of some particles incurs, through\nthe impost of global conservation of the displacement distribution, a delayed,\nnon-local collective process. This non-locality compromises the efficiency with\nwhich configuration space is explored. Both collective mechanisms incur delay\nor stretching of time correlation functions, in particular the particle number\nand flux densities. This paper identifies and distinguishes these mechanisms in\nexisting data from experiments and computer simulations on systems of particles\nwith hard sphere interactions.",
        "positive": "Inter-particle adhesion regulates the surface roughness of growing dense\n  three-dimensional active particle aggregates: Activity and self-generated motion are fundamental features observed in many\nliving and non-living systems. Given that inter-particle adhesive forces are\nknown to regulate particle dynamics, we investigate how adhesion strength\ncontrols the boundary growth and roughness in an active particle aggregate.\nUsing particle based simulations incorporating both activity (birth, death and\ngrowth) and systematic physical interactions (elasticity and adhesion), we\nestablish that inter-particle adhesion strength ($f^{ad}$) controls the surface\nroughness of a densely packed three-dimensional(3D) active particle aggregate\nexpanding into a highly viscous medium. We discover that the surface roughness\nof a 3D active particle aggregate increases in proportion to the inter-particle\nadhesion strength, $f^{ad}$. We show that asymmetry in the radial and\ntangential active particle mean squared displacement (MSD) suppresses 3D\nsurface roughness at lower adhesion strengths. By analyzing the statistical\nproperties of particle displacements at the aggregate periphery, we determine\nthat the 3D surface roughness is driven by the movement of active particle\ntowards the core at high inter-particle adhesion strengths. Our results\nelucidate the physics controlling the expansion of adhesive 3D active particle\ncollectives into a highly viscous medium, with implications into understanding\nstochastic interface growth in active matter systems characterized by self\ngenerated particle flux."
    },
    {
        "anchor": "Interaction of charged patchy protein models with like-charged\n  polyelectrolyte brushes: We study the adsorption of charged patchy particle models (CPPMs) on a thin\nfilm of a like-charged and dense polyelectrolyte (PE) brush (of 50 monomers per\nchain) by means of implicit-solvent, explicit-salt Langevin dynamics computer\nsimulations. Our previously introduced set of CPPMs embraces well-defined one-,\nand two-patched spherical globules, each of the same net charge and (nanometer)\nsize, with mono- and multipole moments comparable to those of small globular\nproteins. We focus on electrostatic effects on the adsorption far away from the\nisoelectric point of typical proteins, i.e., where charge regulation plays no\nrole. Despite the same net charge of the brush and globule we observe large\nbinding affinities up to tens of the thermal energy, kT, which are enhanced by\ndecreasing salt concentration and increasing charge of the patch(es). Our\nanalysis of the distance-resolved potentials of mean force together with a\nphenomenological description of all leading interaction contributions shows\nthat the attraction is strongest at the brush surface, driven by multipolar,\nBorn (self-energy), and counterion-release contributions, dominating locally\nover the monopolar and steric repulsions.",
        "positive": "Crystal phases of two dimensional assembly of triblock Janus particles: Recent experimental work on spherical colloidal particles decorated with two\nhydrophobic poles separated by an electrically-charged middle band (triblock\nJanus particles) has documented self-assembly into a Kagome two-dimensional\nlattice, when particles are confined by gravity at the bottom of the sample\nholder [Q. Chen {\\em et. al.}, Nature, in press]. Here we assess the ability of\na previously proposed simple two-patch effective potential to reproduce the\nexperimental findings. We show that the effective potential is able to\nreproduce the observed crystallization pathway in the Kagome structure. Based\non free energy calculations, we also show that the Kagome lattice is stable at\nlow temperatures and low pressure, but that it transforms into a hexagonal\nlattice with alternating attractive and repulsive bands on increasing pressure."
    },
    {
        "anchor": "Role of Structural Rigidity and Collective Behaviour in the Molecular\n  Design of Gas Hydrates Anti-Agglomerants: Antiagglomerants (AAs) are surface active molecules widely used in the rubber\nand petroleum industry, among others. In the petroleum industry, it is believed\nthat AAs strongly adsorb to the surface of hydrate particles to prevent the\ngrowth of clathrate hydrate within oil pipelines. Small changes in their\nmolecular structures can strongly affect the thermodynamic and kinetic\nstability of the system as a whole. Here we employ molecular dynamics\nsimulations to study the interplay between the modification of the molecular\nstructure, rigidity and collective effects of AAs designed to prevent hydrate\nagglomeration in the conditions encountered in rocking cell experiments. The\nAAs are surface-active compounds with a complex hydrophilic head and three\nhydrophobic tails whose structural rigidity is enhanced with the attachement of\na simple aromatic group. We observe that the aromatic group can positively or\nnegatively affect the performance of the AAs, depending on its location along\nthe hydrophobic tail. Our approach is based on first quantifying the molecular\nmechanisms responsible for the macroscopic performance. Although the mechanisms\nat play depend on the application, the methodology implemented could be\napplicable to other high-tech industries, where the agglomeration of small\nparticles must be controlled.",
        "positive": "Self-Propelling Rotator Driven by Soluto-Capillary Marangoni Flows: The self-propelled, longstanding rotation of the polymer tubing containing\ncamphor continuing for dozens of hours is reported. The rotator is driven by\nthe solutocapillary Marangoni flows owing to the dissolution of camphor. The\nphenomenological model of self-propulsion is suggested and verified. Scaling\nlaws describing the quasi-stationary self-propulsion are proposed and tested\nexperimentally. The change in the surface tension, arising from the dissolution\nof camphor and driving the rotator is estimated as 0.3 mN/m."
    },
    {
        "anchor": "Dynamical pattern formation upon dewetting: Dewetting of thin liquid films is monitored in situ by atomic force\nmicroscopy, results are compared with simulations. The experimental setting is\nmimicked as close as possible using the experimental parameters including the\neffective interface potential. Numerics for the thin film equation are based on\nrecently developed schemes which are up to now the only methods convergent in\nall relevant space dimensions. Temporal evolution and morphology of experiment\nand simulation are compared quantitatively. Our results explain the origin of\ncomplex generic patterns that evolve upon dewetting.",
        "positive": "Multi-scale approach for self-Assembly and protein folding: We develop a multi-scale approach to simulate hydrated nanobio systems under\nrealistic condi- tions (e.g., nanoparticles and protein solutions at\nphysiological conditions over time-scales up to hours). We combine atomistic\nsimulations of water at bio-interfaces (e.g., proteins or membranes) and\nnano-interfaces (e.g., nanoparticles or graphene sheets) and coarse-grain\nmodels of hydration water for protein folding and protein design. We study\nprotein self-assembly and crystallization, in bulk or under confinement, and\nthe kinetics of protein adsorption onto nanoparticles, verify- ing our\npredictions in collaboration with several experimental groups. We try to find\nanswers for fundamental questions (Why water is so important for life? Which\nproperties make water unique for biological processes?) and applications (Can\nwe design better drugs? Can we limit protein- aggregations causing Alzheimer?\nHow to implement nanotheranostic?). Here we focus only on the two larger scales\nof our approach: (i) The coarse-grain description of hydrated proteins and\nprotein folding at sub-nanometric length-scale and milliseconds-to-seconds\ntime-scales, and (ii) the coarse-grain modeling of protein self-assembly on\nnanoparticles at 10-to-100 nm length-scale and seconds-to-hours time-scales."
    },
    {
        "anchor": "Probing dissipation in spreading drops with granular suspensions: In this article, we study the spreading of droplets of density-matched\ngranular suspensions on the surface of a solid. Bidispersity of the particle\nsize distribution enriches the conclusions drawn from monodisperse experiments\nby highlighting key elements of the wetting dynamics. In all cases, the\nrelation between the dynamic contact angle and the velocity of the contact line\nfollows a similar relation as that of a simple fluid, despite the complexity\nintroduced by the presence of particles. We extract from this relation an\napparent wetting viscosity of the suspensions that differs from that measured\nin the bulk. Dimensional analysis supported by experimental measurements yields\nestimate of the size of the region inside the droplet where the value of the\ndynamic contact angle depends on a balance of viscous dissipation and capillary\nstresses. Depending on how particle size compares with this viscous cut-off\nlength seems crucial in determining the value of the apparent wetting\nviscosity. With bimodal blends, the particle size ratio can be used to show the\neffects of the local structure and volume fraction at the contact line, both\nimpacting the value of the corresponding wetting viscosity.",
        "positive": "Binding of Curvature-Inducing Proteins onto Biomembranes: We review the theoretical analyses and simulations of the interactions\nbetween curvature-inducing proteins and biomembranes. Laterally isotropic\nproteins induce spherical budding, whereas anisotropic proteins, such as\nBin/Amphiphysin/Rvs (BAR) superfamily proteins, induce tabulation. Both types\nof proteins can sense the membrane curvature. We describe the theoretical\nanalyses of various transitions of protein binding accompanied by a change in\nvarious properties, such as the number of buds, the radius of membrane tubes,\nand the nematic order of anisotropic proteins. Moreover, we explain the\nmembrane-mediated interactions and protein assembly. Many types of membrane\nshape transformations (spontaneous tubulation, formation of polyhedral\nvesicles, polygonal tubes, periodic bumps, and network structures, etc.) have\nbeen demonstrated by coarse-grained simulations. Furthermore, traveling waves\nand Turing patterns under the coupling of reaction-diffusion dynamics and\nmembrane deformation are described."
    },
    {
        "anchor": "Stochastic Properties of Static Friction: The onset of frictional motion is mediated by rupture-like slip fronts, which\nnucleate locally and propagate eventually along the entire interface causing\nglobal sliding. The static friction coefficient is a macroscopic measure of the\napplied force at this particular instant when the frictional interface loses\nstability. However, experimental studies are known to present important scatter\nin the measurement of static friction; the origin of which remains unexplained.\nHere, we study the nucleation of local slip at interfaces with slip-weakening\nfriction of random strength and analyze the resulting variability in the\nmeasured global strength. Using numerical simulations that solve the\nelastodynamic equations, we observe that multiple slip patches nucleate\nsimultaneously, many of which are stable and grow only slowly, but one reaches\na critical length and starts propagating dynamically. We show that a\ntheoretical criterion based on a static equilibrium solution predicts\nquantitatively well the onset of frictional sliding. We develop a Monte-Carlo\nmodel by adapting the theoretical criterion and pre-computing modal convolution\nterms, which enables us to run efficiently a large number of samples and to\nstudy variability in global strength distribution caused by the stochastic\nproperties of local frictional strength. The results demonstrate that an\nincreasing spatial correlation length on the interface, representing geometric\nimperfections and roughness, causes lower global static friction. Conversely,\nsmaller correlation length increases the macroscopic strength while its\nvariability decreases. We further show that randomness in local friction\nproperties is insufficient for the existence of systematic precursory slip\nevents. Random or systematic non-uniformity in the driving force, such as\npotential energy or stress drop, is required for arrested slip fronts. Our\nmodel and observations...",
        "positive": "Banded spatiotemporal chaos in sheared nematogenic fluids: We present the results of a numerical study of a model of the hydrodynamics\nof a sheared nematogenic fluid, taking into account the effects of order\nparameter stresses on the velocity profile, but allowing spatial variations\nonly in the gradient direction. When parameter values are such that the stress\nfrom orientational distortions is comparable to the bare viscous stress, the\nsystem exhibits steady states with the characteristics of shear banding. In\naddition, nonlinearity in the coupling of extensional flow to orientation leads\nto the appearance of a new steady state in which the features of both\nspatiotemporal chaos and shear banding are present."
    },
    {
        "anchor": "The adjoint problem in the presence of a deformed surface: the example\n  of the Rosensweig instability on magnetic fluids: The Rosensweig instability is the phenomenon that above a certain threshold\nof a vertical magnetic field peaks appear on the free surface of a horizontal\nlayer of magnetic fluid. In contrast to almost all classical hydrodynamical\nsystems, the nonlinearities of the Rosensweig instability are entirely\ntriggered by the properties of a deformed and a priori unknown surface. The\nresulting problems in defining an adjoint operator for such nonlinearities are\nillustrated. The implications concerning amplitude equations for pattern\nforming systems with a deformed surface are discussed.",
        "positive": "Kinks, rings, and rackets in filamentous structures: Carbon nanotubes and biological filaments each spontaneously assemble into\nkinked helices, rings, and \"tennis racket\" shapes due to competition between\nelastic and interfacial effects. We show that the slender geometry is a more\nimportant determinant of the morphology than any molecular details. Our\nmesoscopic continuum theory is capable of quantifying observations of these\nstructures, and is suggestive of their occurrence in other filamentous\nassemblies as well."
    },
    {
        "anchor": "Multiscale Poromechanics of Wet Cement Paste: Capillary effects such as imbibition-drying cycles impact the mechanics of\ngranular systems over time. A multiscale poromechanics framework was applied to\ncement paste, that is the most common building material, experiencing broad\nhumidity variations over the lifetime of infrastructure. First, the liquid\ndensity distribution at intermediate to high relative humidities is obtained\nusing a lattice gas density functional method together with a realistic\nnano-granular model of cement hydrates. The calculated adsorption/desorption\nisotherms and pore size distributions are discussed and compare well to\nnitrogen and water experiments. The standard method for pore size distribution\ndetermination from desorption data is evaluated. Then, the integration of the\nKorteweg liquid stress field around each cement hydrate particle provided the\ncapillary forces at the nanoscale. The cement mesoscale structure was relaxed\nunder the action of the capillary forces. Local irreversible deformations of\nthe cement nano-grains assembly were identified due to liquid-solid\ninteractions. The spatial correlations of the nonaffine displacements extend to\na few tens of nm. Finally, the Love-Weber method provided the homogenized\nliquid stress at the micronscale. The homogenization length coincided with the\nspatial correlation length nonaffine displacements. Our results on the solid\nresponse to capillary stress field suggest that the micronscale texture is not\naffected by mild drying, while local irreversible deformations still occur.\nThese results pave the way towards understanding capillary phenomena induced\nstresses in heterogeneous porous media ranging from construction materials,\nhydrogels to living systems.",
        "positive": "Sorting of multiple molecular species on cell membranes: Eukaryotic cells maintain their inner order by a hectic process of\ndistillation of molecular factors taking place on the surface of their lipid\nmembranes. To understand the properties of this molecular sorting process, a\nphysical model of the process has been recently proposed [arXiv:1811.06760],\nbased on (a) the phase separation of a single, initially dispersed molecular\nspecies into spatially localized sorting domains on the lipid membrane, and (b)\ndomain-induced membrane bending leading to the nucleation of submicrometric\nlipid vesicles, naturally enriched in the molecules of the engulfed sorting\ndomain. The analysis of the model has shown the existence of an optimal region\nof the parameter space where sorting is most efficient. Here, the model is\nextended to account for the simultaneous distillation of a pool of distinct\nmolecular species. We find that the mean time spent by sorted molecules on the\nmembrane increases with the heterogeneity of the pool (i.e., the number of\ndistinct molecular species sorted) according to a simple scaling law, and that\na large number of distinct molecular species can in principle be sorted in\nparallel on a typical cell membrane region without significantly interfering\nwith each other. Moreover, sorting is found to be most efficient when the\ndistinct molecular species have comparable homotypic affinities. We also\nconsider how valence (i.e., the average number of interacting neighbors of a\nmolecule in a sorting domain) affects the sorting process, finding that\nhigher-valence molecules can be sorted with greater efficiency than\nlower-valence molecules."
    },
    {
        "anchor": "Polymer nano-doplets forming liquid bridges in chemically structured\n  slit pores: A computer simulation: Using a coarse-grained bead-spring model of flexible polymer chains, the\nstructure of a polymeric nanodroplet adsorbed on a chemically decorated flat\nwall is investigated by means of Molecular Dynamics simulation. We consider\nsessile drops on a lyophilic (attractive for the monomers) region of circular\nshape with radius R_D while the remaining part of the substrate is lyophobic.\nThe variation of the droplet shape, including its contact angle, with R_D is\nstudied, and the density profiles across these droplets also are obtained.\n  In addition, the interaction of droplets adsorbed on two walls forming a slit\npore with two lyophilic circular regions just opposite of one another is\ninvestigated, paying attention to the formation of a liquid bridge between both\nwalls. A central result of our study is the measurement of the force between\nthe two substrate walls at varying wall separation as well as the kinetics of\ndroplet merging. Our results are compared to various phenomenological theories\ndeveloped for liquid droplets of mesoscopic rather than nanoscopic size.",
        "positive": "Confinement effects on the properties of Janus dimers: Confinement has been suggested as a tool to tune the self-assembly properties\nof nanoparticles, surfactants, polymers and colloids. In this way, we explore\nthe phase diagram of Janus nanoparticles using Molecular Dynamics simulations.\nThe nanoparticle was modeled as a dimer made by one monomer that interacts by a\nstandard Lennard Jones potential and another monomer that is modeled using a\ntwo-length scale shoulder potential. This specific design of nanoparticle\nexhibits in bulk distinct self-assembled structures and water-like diffusion\nanomaly. Our results indicate that besides the aggregates observed in bulk, new\nstructures are observed under confinement. Also, the dynamic and thermodynamic\nbehavior of the fluid phase are affected. The systems show a reentrant fluid\nphase and density anomaly. None of these two features were observed in bulk.\nOur results show that geometrical confinement leads to new structural,\nthermodynamical and dynamical behavior for this Janus nanoparticle."
    },
    {
        "anchor": "Crowding effects on the structural transitions in a flexible helical\n  homopolymer: We elucidate the structural transitions in a helical off-lattice homopolymer\ninduced by crowding agents, as function of the number of monomers ($N$) and\nvolume fraction ($\\phi_c$) of crowding particles. At $\\phi_c = 0$, the\nhomopolymer undergoes transitions from a random coil to a helix, helical\nhairpin \\textbf{HH}, and helix bundle \\textbf{HB} structures depending on $N$,\nand temperature. Crowding induces chain compaction that can promote \\textbf{HH}\nor \\textbf{HB} formation depending on $\\phi_c$. Typically, the helical content\ndecreases which is reflected in the decrease in the transition temperatures\nthat depend on $\\phi_c$, $N$, and the size of the crowding particles.",
        "positive": "Stokes' Cradle: Normal Three-Body Collisions between Wetted Particles: In this work, a combination of experiments and theory is used to investigate\nthree-body, normal collisions between solid particles with a liquid coating\n(i.e., \"wetted\" particles). Experiments are carried out using a Stokes' cradle,\nan apparatus inspired by the Newton's cradle desktop toy except with wetted\nparticles. Unlike previous work on two-body systems, which may either\nagglomerate or rebound upon collision, four outcomes are possible in three-body\nsystems: fully agglomerated, Newton's cradle (striker and target particle it\nstrikes agglomerate), reverse Newton's cradle (targets agglomerate while\nstriker separates), and fully separated. Post-collisional velocities are\nmeasured over a range of parameters. For all experiments, as the impact\nvelocity increases, the progression of outcomes observed is fully agglomerated,\nreverse Newton's cradle, and fully separated. Notably, as the viscosity of the\noil increases, experiments reveal a decrease in the critical Stokes number (the\nStokes number that demarcates a transition from agglomeration to separation)\nfor both sets of adjacent particles. A scaling theory is developed based on\nlubrication forces and particle deformation and elasticity. Unlike previous\nwork for two-particle systems, two pieces of physics are found to be critical\nin the prediction of a regime map that is consistent with experiments: (i) an\nadditional resistance upon rebound of the target particles due to the\npre-existing liquid bridge between them (which has no counterpart in\ntwo-particle collisions), and (ii) the addition of a rebound criterion due to\nglass transition of the liquid layer at high pressure between colliding\nparticles."
    },
    {
        "anchor": "Efficient simulations of charged colloidal dispersions: A density\n  functional approach: A numerical method is presented for first-principle simulations of charged\ncolloidal dispersions in electrolyte solutions. Utilizing a smoothed profile\nfor colloid-solvent boundaries, efficient mesoscopic simulations are enabled\nfor modeling dispersions of many colloidal particles exhibiting many-body\nelectrostatic interactions. The validity of the method was examined for simple\ncolloid geometries, and the efficiency was demonstrated by calculating stable\nstructures of two-dimensional dispersions, which resulted in the formation of\ncolloidal crystals.",
        "positive": "Non-monotonous translocation time of polymers across pores: Polymers confined in corrugated channels, i.e. channels of varying amplitude,\ndisplay {multiple local maxima and minima of the diffusion coefficient upon\nincreasing their degree of polymerization $N$}. We propose a theoretical\neffective free energy for linear polymers based on a Fick-Jacobs approach. We\nvalidate the predictions against numerical data, obtaining quantitative\nagreement for {the effective free energy, the diffusion coefficient and the\nMean First Passage Time}. Finally, we employ the effective free energy to\ncompute the polymer lengths $N_{min}$ at which the diffusion coefficient\npresents a minimum: we find a scaling expression that we rationalize with a\nblob model. Our results could be useful to design porous adsorbers, that\nseparate polymers of different sizes without the action of an external flow."
    },
    {
        "anchor": "Synthesis, characterization, and biological evaluation of gelatin-based\n  scaffolds: This thesis presents the development of entropy-elastic gelatin based\nnetworks in the form of films or scaffolds. The materials have good prospects\nfor biomedical applications, especially in the context of bone regeneration.\nEntropy-elastic gelatin based hydrogel films with varying crosslinking\ndensities were prepared with tailored mechanical properties. Gelatin was\ncovalently crosslinked in water above its sol gel transition, which suppressed\nthe gelatin chain helicity. Amorphous films were prepared with tailorable\ndegrees of swelling and wet state Young's modulus. The knowledge gained with\nthis bulk material was transferred to the integrated process of foaming and\ncrosslinking to obtain porous gelatin-based scaffolds. A gelatin solution was\nfoamed in the presence of saponin and the resulting foam was fixed by chemical\ncrosslinking with a diisocyanate. The scaffolds were analyzed in the dry state\nby micro computed tomography (\\mu CT, porosity: 65\\pm 11-73\\pm 14 vol.-%), and\nscanning electron microscopy (SEM, pore size: 117\\pm 28-166 \\pm 32 \\mu m).\nAfter equilibration with water, the scaffolds were form-stable and displayed\nshape recovery after removal of mechanical loads. The composition dependent\ncompression moduli (Ec: 10 50 kPa) were comparable to the bulk micromechanical\nYoung's moduli, which were measured by atomic force microscopy (AFM). The\nhydrolytic degradation profile could be adjusted, and a controlled decrease of\nmechanical properties was observed. The scaffold cytotoxicity and immunologic\nresponses were analyzed in vitro. Indirect eluate tests were carried out with\nL929 cells so that fully cytocompatible scaffolds were obtained. Furthermore,\nthe material immune response was investigated in vitro. Minimal material\nendotoxin contamination was successfully achieved (<0.5 EU/mL) by using\nlow-endotoxin gelatin and performing all synthetic steps in cleanroom.",
        "positive": "Ratchet transport powered by chiral active particles: We numerically investigate the ratchet transport of mixtures of active and\npassive particles in a transversal asymmetric channel.A big passive particle is\nimmersed in a 'sea' of active particles. Due to the chirality of active\nparticles, the longitudinal directed transport is induced by the transversal\nasymmetry. For the active particles, the chirality completely determines the\ndirection of the ratchet transport, the counterclockwise and clockwise\nparticles move to the opposite directions and can be separated. However, for\nthe passive particle, the transport behavior becomes complicated, the direction\nis determined by competitions among the chirality, the self-propulsion speed,\nand the packing fraction. Interestingly, within certain parameters, the passive\nparticle moves to the left,while active particles move to the right. In\naddition, there exist optimal parameters(the chirality, the height of the\nbarrier, the self-propulsion speed and the packing fraction) at which the\nrectified efficiency takes its maximal value. Our findings could be used for\nthe experimental pursuit of the ratchet transport powered by chiral active\nparticles."
    },
    {
        "anchor": "Casimir and pseudo-Casimir interactions in confined polyelectrolytes: We investigate the pseudo-Casimir force acting between two charged surfaces\nconfining a single polyelectrolyte chain with opposite charge. We expand the\nexact free energy to the second order in the local electrostatic field as well\nas the replicated polymer density field around the mean-field (saddle-point)\nsolution. The quadratic terms lead to a fluctuation interaction that is partly\ndue to the (thermal) Casimir effect for the confined electrostatic field and\npartly due to the pseudo-Casimir effect due to the confined replicated polymer\ndensity field. We study the intersurface separation dependence of both effects\nand show that the pseudo-Casimir effect leads to a long range attraction\nbetween the surfaces that decays with an anomalous algebraic exponent of $\\sim\n1.7$, smaller than the standard exponent of 2 in the case of Casimir\ninteractions.",
        "positive": "Geometrical Frustration: A Study of 4d Hard Spheres: The smallest maximum kissing-number Voronoi polyhedron of 3d spheres is the\nicosahedron and the tetrahedron is the smallest volume that can show up in\nDelaunay tessalation. No periodic lattice is consistent with either and hence\nthese dense packings are geometrically frustrated. Because icosahedra can be\nassembled from almost perfect tetrahedra, the terms \"icosahedral\" and\n\"polytetrahedral\" packing are often used interchangeably, which leaves the true\norigin of geometric frustration unclear. Here we report a computational study\nof freezing of 4d hard spheres, where the densest Voronoi cluster is compatible\nwith the symmetry of the densest crystal, while polytetrahedral order is not.\nWe observe that, under otherwise comparable conditions, crystal nucleation in\n4d is less facile than in 3d. This suggest that it is the geometrical\nfrustration of polytetrahedral structures that inhibits crystallization."
    },
    {
        "anchor": "Self-Consistent-Field Study of the Alignment by an Electric Field of a\n  Cylindrical Phase of Block Copolymer: Self-Consistent Field Theory is applied to a film of cylindrical-forming\nblock copolymer subject to a surface field which tends to align the cylinders\nparallel to electrical plates, and to an external electric field tending to\nalign them perpendicular to the plates. The Maxwell equations and\nself-consistent field equations are solved exactly, numerically, in real space.\nBy comparing the free energies of different configurations, we show that for\nweak surface fields, the phase of cylinders parallel to the plates makes a\ndirect transition to a phase in which the cylinders are aligned with the field\nthroughout the sample. For stronger surface fields, there is an intermediate\nphase in which cylinders in the interior of the film, aligned with the field,\nterminate near the plates. For surface fields which favor the minority block,\nthere is a boundary layer of hexagonal symmetry at the plates in which the\nmonomers favored by the surface field occupy a larger area than they would if\nthe cylinders extended to the surface.",
        "positive": "Diffusion of Chiral Janus Particles in a Sinusoidal Channel: We investigate the transport diffusivity of artificial microswimmers, a.k.a.\nJanus particles, moving in a sinusoidal channel in the absence of external\nbiases. Their diffusion constant turns out to be quite sensitive to the\nself-propulsion mechanism and the geometry of the channel compartments. Our\nanalysis thus suggests how to best control the diffusion of active Brownian\nmotion in confined geometries."
    },
    {
        "anchor": "Optical Experiments on a Crystallizing Hard Sphere - Polymer Mixture at\n  Coexistence: We report on the crystallization kinetics in an entropically attractive\ncolloidal system using a combination of time resolved scattering methods and\nmicroscopy. Hard sphere particles are polystyrene microgels swollen in a good\nsolvent (radius a=380nm, starting volume fraction 0.534) with the short ranged\nattractions induced by the presence of short polymer chains (radius of gyration\nrg = 3nm, starting volume fraction 0.0224). After crystallization, stacking\nfaulted face centred cubic crystals coexist with about 5% of melt remaining in\nthe grain boundaries. From the Bragg scattering signal we infer the amount of\ncrystalline material, the average crystallite size and the number density of\ncrystals as a function of time. This allows to discriminate an early stage of\nconversion, followed by an extended coarsening stage. The small angle\nscattering (SALS) appears only long after completed conversion and exhibits\nFurukawa scaling for all times. Additional microscopic experiments reveal that\nthe grain boundaries have a reduced Bragg scattering power but possess an\nincreased refractive index. Fits of the Furukawa function indicate that the\ndimensionality of the scatterers decreases from 2.25 at short times to 1.65 at\nlate times and the characteristic length scale is slightly larger than the\naverage crystallite size. Together this suggests the SALS signal is due\nscattering from a foam like grain boundary network as a whole.",
        "positive": "Automatic Multi-Objective Optimization of Coarse-Grained Lipid Force\n  Fields Using SwarmCG: The development of coarse-grained (CG) molecular models typically requires a\ntime-consuming iterative tuning of parameters in order to have the approximated\nCG models behaving correctly and consistently with, e.g., available\nhigher-resolution simulation data and/or experimental observables. Automatic\ndata-driven approaches are increasingly used to develop accurate models for\nmolecular dynamics simulations. But the parameters obtained via such automatic\nmethods often make use of specifically-designed interaction potentials, and are\ntypically poorly transferable to molecular systems or conditions other than\nthose used for training them. Using a multi-objective approach in combination\nwith an automatic optimization engine (SwarmCG), here we show that it is\npossible to optimize CG models that are also transferable, obtaining optimized\nCG force fields (FFs). As a proof of concept, here we use lipids, for which we\ncan avail of reference experimental data (area per lipid, bilayer thickness)\nand reliable atomistic simulations to guide the optimization. Once the\nresolution of the CG models (mapping) is set as an input, SwarmCG optimizes the\nparameters of the CG lipid models iteratively and simultaneously against\nhigher-resolution simulations (bottom-up) and experimental data (top-down\nreferences). Including different types of lipid bilayers in the training set in\na parallel optimization guarantees the transferability of the optimized lipid\nFF parameters. We demonstrate that SwarmCG can reach satisfactory agreement\nwith experimental data for different resolution CG FFs. We also obtain\nstimulating insights on the precision-resolution balance of the FFs. The\napproach is general and can be effectively used to develop new FFs, as well as\nto improve existing ones."
    },
    {
        "anchor": "Analysis of radial segregation of granular mixtures in a rotating drum: This paper considers the segregation of a granular mixture in a rotating\ndrum. Extending a recent kinematic model for grain transport on sandpile\nsurfaces to the case of rotating drums, an analysis is presented for radial\nsegregation in the rolling regime, where a thin layer is avalanching down while\nthe rest of the material follows rigid body rotation. We argue that segregation\nis driven not just by differences in the angle of repose of the species, as has\nbeen assumed in earlier investigations, but also by differences in the size and\nsurface properties of the grains. The cases of grains differing only in size\n(slightly or widely) and only in surface properties are considered, and the\npredictions are in qualitative agreement with observations. The model yields\nresults inconsistent with the assumptions for more general cases, and we\nspeculate on how this may be corrected.",
        "positive": "Efficient Monte Carlo simulation of a glass forming binary mixture: We propose and use a novel, hybrid Monte Carlo algorithm that combines\nconfigurational bias particle swaps with parallel tempering. We use this new\nmethod to simulate a standard model of a glass forming binary mixture above and\nbelow the so-called mode-coupling temperature, Tmct. We find that an ansatz\nthat was used previously to extrapolate thermodynamic quantities to\ntemperatures below Tmct breaks down in the vicinity of the mode-coupling\ntemperature. Thus, previous estimates of the so-called Kauzmann temperature\nneed to be reexamined. Also, we find that the Adam-Gibbs relations D ~\nexp(-a/TSc) and tau ~ exp(b/TSc), which connect the diffusion coefficient D and\nthe relaxation time tau with the configurational entropy Sc, are valid for all\ntemperatures for which the configurational and vibrational contributions to the\nfree energy decouple."
    },
    {
        "anchor": "Temperature field and heat generation at the tip of a cutout in a\n  viscoelastic solid body undergoing loading: Using the finite element method we quantitatively analyse temperature field\nevolution in a viscoelastic solid undergoing a loading--unloading process. In\nparticular we investigate the temperature field inside a Kelvin--Voigt type\nviscoelastic body with a thin cutout. We find that the viscosity significantly\ncontributes to the temperature field changes, and that the temperature field\nchanges initiated by the loading--unloading process are strongly concentrated\nat the tip of the thin cutout. The predicted temperature field qualitatively\ncorresponds to the temperature field observed in experiments focused on\nsimultaneous heat and strain measurements at the crack tip inside materials\nsuch as the filled rubber.",
        "positive": "Jamming in granular hopper flow: Large-scale three dimensional molecular dynamics simulations of hopper flow\nare presented. The flow rate of the system is controlled by the width of the\naperture at the bottom. As the steady-state flow rate is reduced, the force\ndistribution $P(f)$ changes only slightly, while there is a large change in the\nimpulse distribution $P(i)$. In both cases, the distributions show an increase\nin small forces or impulses as the systems approach jamming, the opposite of\nthat seen in previous Lennard-Jones simulations. This occurs dynamically as\nwell for a hopper that transitions from a flowing to a jammed state over time.\nThe final jammed $P(f)$ is quite distinct from a poured packing $P(f)$ in the\nsame geometry. The change in $P(i)$ is a much stronger indicator of the\napproach to jamming. The formation of a peak or plateau in $P(f)$ at the\naverage force is not a general feature of the approach to jamming."
    },
    {
        "anchor": "Universal mechanical response of metallic glasses during\n  strain-rate-dependent uniaxial compression: Experimental data on the compressive strength $\\sigma_{\\rm max}$ versus\nstrain rate ${\\dot \\varepsilon}_{\\rm eng}$ for metallic glasses undergoing\nuniaxial compression shows significantly different behavior for different\nalloys. For some metallic glasses, $\\sigma_{\\rm max}$ decreases with increasing\n${\\dot \\varepsilon}_{\\rm eng}$, for others, $\\sigma_{\\rm max}$ increases with\nincreasing ${\\dot \\varepsilon}_{\\rm eng}$, and for others $\\sigma_{\\rm max}$\nversus ${\\dot \\varepsilon}_{\\rm eng}$ is nonmonotonic. Using numerical\nsimulations of metallic glasses undergoing uniaxial compression at nonzero\nstrain rate and temperature, we show that they obey a universal relation for\nthe compressive strength versus temperature, which determines their mechanical\nresponse. At low ${\\dot \\varepsilon}_{\\rm eng}$, increasing strain rate leads\nto increases in temperature and decreases in $\\sigma^*_{\\rm max}$, whereas at\nhigh ${\\dot \\varepsilon}_{\\rm eng}$, increasing strain rate leads to decreases\nin temperature and increases in $\\sigma^*_{\\rm max}$. This non-monotonic\nbehavior of $\\sigma^*_{\\rm max}$ versus temperature causes the nonmonotonic\nbehavior of $\\sigma^*_{\\rm max}$ versus ${\\dot \\varepsilon}_{\\rm eng}$.\nVariations in the internal dissipation change the characteristic strain rate at\nwhich the nonmonotonic behavior occurs. These results are general for a wide\nrange of metallic glasses with different atomic interactions, damping\ncoefficients, and chemical compositions.",
        "positive": "A universal phase-field mixture representation of thermodynamics and\n  shock wave mechanics in porous soft biologic continua: A continuum mixture theory is formulated for large deformations, thermal\neffects, phase interactions, and degradation of soft biologic tissues. Such\ntissues consist of one or more solid and fluid phases and can demonstrate\nnonlinear anisotropic elastic, viscoelastic, thermoelastic, and poroelastic\nphysics. Under extremely large or rapid deformations, for example impact or\nshock loading, tissues may fracture, tear, or rupture. Mechanisms are\nencompassed in a universal, thermodynamically consistent formulation that\ncombines the continuum theory of mixtures with phase-field mechanics of\nfracture. A metric tensor of generalized Finsler space supplies geometric\ninsight on effects rearrangements of microstructure, for example degrading\ncollagen fibers. Governing equations are derived, and energy potentials and\nkinetic laws posited, for generic soft porous tissues with solid and liquid or\ngas phases. Shock waves are modeled as singular surfaces; Hugoniot states and\nshock decay are studied analytically. Suitability of the framework for\nrepresenting blood, skeletal muscle, and liver is demonstrated. Insight into\nphysics presently unresolved by experiments is obtained."
    },
    {
        "anchor": "Quantum Chemistry at Finite Temperature: In this article, we present emerging fields of quantum chemistry at finite\ntemperature. We discuss its recent developments on both experimental and\ntheoretical fronts. First, we describe several experimental investigations\nrelated to the temperature effects on the structures, electronic spectra, or\nbond rupture forces for molecules. These include the analysis of the\ntemperature impact on the pathway shifts for the protein unfolding by atomic\nforce microscopy (AFM), the temperature dependence of the absorption spectra of\nelectrons in solvents, and the temperature influence over the intermolecular\nforces measured by the AFM. On the theoretical side, we review advancements\nmade by the author in the coming fields of quantum chemistry at finite\ntemperature. Starting from the Bloch equation, we have derived the sets of\nhierarchy equations for the reduced density operators in both canonical and\ngrand canonical ensembles. They provide a law according to which the reduced\ndensity operators vary in temperature for the identical and interacting\nmany-body systems. By taking the independent particle approximation, we have\nsolved the equations in the case of a grand canonical ensemble, and obtained an\nenergy eigenequation for the molecular orbitals at finite temperature. The\nexplicit expression for the temperature-dependent Fock operator is also given.\nThey form a mathematical foundation for the examination of the molecular\nelectronic structures and their interplay with finite temperature. Moreover, we\nclarify the physics concerning the temperature effects on the electronic\nstructures or processes of the molecules, which is crucial for both theoretical\nunderstanding and computation. Finally, ....",
        "positive": "Complex-tensor theory of simple smectics: Smectic materials represent a unique state between fluids and solids,\ncharacterized by orientational and partial positional order, making them\nnotoriously difficult to model, particularly in confining geometries. We\npropose a complex order parameter tensor to describe the local degree of\nlamellar ordering, layer displacement and orientation. The theory accounts for\nboth dislocations and disclinations, as well as arrested configurations and\ncolloid-induced local ordering. It considerably simplifies numerics,\nfacilitating studies on the dynamics of topologically complex lamellar systems."
    },
    {
        "anchor": "Bendability parameter for twisted ribbons to describe longitudinal\n  wrinkling and delineate the near-threshold regime: We propose a dimensionless bendability parameter, $\\epsilon^{-1} =\n[\\left(h/W\\right)^2 T^{-1}]^{-1}$ for wrinkling of thin, twisted ribbons with\nthickness $h$, width $W$, and tensional strain $T$. Bendability permits\nefficient collapse of data for wrinkle onset, wavelength, critical stress, and\nresidual stress, demonstrating longitudinal wrinkling's primary dependence on\nthis parameter. This new parameter also allows us to distinguish the highly\nbendable range ($\\epsilon^{-1} > 20$) from moderately bendable samples\n($\\epsilon^{-1} \\in (0,20]$). We identify scaling relations to describe\nlongitudinal wrinkles that are valid across our entire set of simulated\nribbons. When restricted to the highly bendable regime, simulations confirm\ntheoretical near-threshold (NT) predictions for wrinkle onset and wavelength.",
        "positive": "A reduced-order, rotation-based model for thin hard-magnetic plates: We develop a reduced-order model for thin plates made of hard\nmagnetorheological elastomers (hard-MREs), which are materials composed of\nhard-magnetic particles embedded in a polymeric matrix. First, we propose a new\nmagnetic potential, as an alternative to an existing torque-based 3D continuum\ntheory of hard-MREs, obtained by reformulating the remnant magnetization of a\ndeformed hard-MRE body. Specifically, the magnetizations in the initial and\ncurrent configurations are related by the rotation tensor decomposed from the\ndeformation gradient, independently of stretching deformation. This description\nis motivated by recently reported observations in microscopic homogenization\nsimulations. Then, we derive a 2D plate model through the dimensional reduction\nof our proposed rotation-based 3D theory. For comparison, we also provide a\nsecond plate model derived from the existing 3D theory. Finally, we perform\nprecision experiments to thoroughly evaluate the proposed 3D and 2D models on\nhard-magnetic plates under various magnetic and mechanical loading conditions.\nWe demonstrate that our rotation-based modification of the magnetic potential\nis crucial in correctly capturing the behavior of plates subjected to an\napplied field aligned with the magnetization, and undergoing in-plane\nstretching. In all the tested cases, our rotation-based 3D and 2D models yield\npredictions in excellent quantitative agreement with the experiments and can\nthus serve as predictive tools for the rational design of hard-magnetic plate\nstructures."
    },
    {
        "anchor": "Absence of a Diffusion Anomaly in Water Perpendicular to Hydrophobic\n  Nanoconfining Walls: We perform molecular dynamics simulations to investigate the diffusive motion\nof TIP5P water in the direction perpendicular to the two hydrophobic confining\nwalls. To calculate the diffusion coefficient, we use the concept of the\ncharacteristic residence time which is calculated from the exponential decay of\nthe residence time probability distribution function. We find that a diffusion\nanomaly of water, increase of diffusion upon compression, is absent in the\ndirection perpendicular to the confining walls down to the lowest temperature\nwe simulate, 220K, whereas there is a diffusion anomaly, similar to that in\nbulk water, in the direction parallel to the walls. The absence of a diffusion\nanomaly may arise mainly due to nanoconfinement, rather than due to the\nhydrophobic property of the confining walls.",
        "positive": "Free energy approach to micellization and aggregation: Equilibrium,\n  metastability, and kinetics: We review a recently developed micellization theory, which is based on a\nfree-energy approach and offers several advantages over the conventional one,\nbased on mass action and rate equations. As all the results are derived from a\nsingle free-energy expression, one can adapt the theory to different scenarios\nby merely modifying the initial expression. We present results concerning\nvarious features of micellization out of equilibrium, such as the existence of\nmetastable aggregates (premicelles), micellar nucleation and growth, transient\naggregates, and final relaxation toward equilibrium. Several predictions that\nawait experimental investigation are discussed."
    },
    {
        "anchor": "One size fits all: equilibrating chemically different polymer liquids\n  through universal long-wavelength description: Mesoscale behavior of polymers is frequently described by universal laws.\nThis physical property motivates us to propose a new modeling concept, grouping\npolymers into classes with a common long-wavelength representation. In the same\nclass samples of different materials can be generated from this representation,\nencoded in a single library system. We focus on homopolymer melts, grouped\naccording to the invariant degree of polymerization. They are described with a\nbead-spring model, varying chain stiffness and density to mimic chemical\ndiversity. In a renormalization group-like fashion library samples provide a\nuniversal blob-based description, hierarchically backmapped to create\nconfigurations of other class-members. Thus large systems with\nexperimentally-relevant invariant degree of polymerizations (so far accessible\nonly on very coarse-grained level) can be microscopically described.\nEquilibration is verified comparing conformations and melt structure with\nsmaller scale conventional simulations.",
        "positive": "Orientation Correlation in Simplified Models of Polymer Melts: We investigate mutual local chain order in systems of fully flexible polymer\nmelts in a simple generic bead-spring model. The excluded-volume interaction\ntogether with the connectivity leads to local ordering effects which are\nindependent of chain length between 25 and 700 monomers, i.e. in the Rouse as\nwell as in the reptation regime. These ordering phenomena extend to a distance\nof about 3 to 4 monomer sizes and decay to zero afterwards."
    },
    {
        "anchor": "Density scaling of generalized Lennard-Jones fluids in different\n  dimensions: Liquids displaying strong virial-potential energy correlations conform to an\napproximate density scaling of their structural and dynamical observables. This\nscaling property does not extend to the entire phase diagram, in general. The\nvalidity of the scaling can be quantified by a correlation coefficient. In this\nwork a simple scheme to predict the correlation coefficient and the\ndensity-scaling exponent is presented. Although this scheme is exact only in\nthe dilute gas regime or in high dimension d, a comparison with results from\nmolecular dynamics simulations in d = 1 to 4 shows that it reproduces well the\nbehavior of generalized Lennard-Jones systems in a large portion of the fluid\nphase.",
        "positive": "Collision-induced torque mediates transition of chiral dynamic patterns\n  formed by active particles: It is still challenging to control dynamic self-organization patterns of\nself-propelled particles. Although varieties of patterns associated with\nchirality have been observed, essential control factors determining patterns\nremain unclear. Here, we explore numerically how torque upon particle collision\naffects dynamic self-organization. Based on the particle-based model with both\ncollision-induced torque and torque in self-propulsion, we find that\nintroducing collision-induced torque turns homogeneous bi-polar orientation\ntemplated by bi-directional alignment into rotating mono-polar flocks."
    },
    {
        "anchor": "Scattering function of semiflexible polymer chains under good solvent\n  conditions: Using the pruned-enriched Rosenbluth Monte Carlo algorithm, the scattering\nfunctions of semiflexible macromolecules in dilute solution under good solvent\nconditions are estimated both in $d=2$ and $d=3$ dimensions, considering also\nthe effect of stretching forces. Using self-avoiding walks of up to $N = 25600$\nsteps on the square and simple cubic lattices, variable chain stiffness is\nmodeled by introducing an energy penalty $\\epsilon_b$ for chain bending;\nvarying $q_b=\\exp (- \\epsilon_b/k_BT)$ from $q_b=1$ (completely flexible\nchains) to $q_b = 0.005$, the persistence length can be varied over two orders\nof magnitude. For unstretched semiflexible chains we test the applicability of\nthe Kratky-Porod worm-like chain model to describe the scattering function, and\ndiscuss methods for extracting persistence length estimates from scattering.\nWhile in $d=2$ the direct crossover from rod-like chains to self-avoiding walks\ninvalidates the Kratky-Porod description, it holds in $d=3$ for stiff chains if\nthe number of Kuhn segments $n_K$ does not exceed a limiting value $n^*_K$\n(which depends on the persistence length). For stretched chains, the Pincus\nblob size enters as a further characteristic length scale. The anisotropy of\nthe scattering is well described by the modified Debye function, if the actual\nobserved chain extension $<X>$ (end-to-end distance in the direction of the\nforce) as well as the corresponding longitudinal and transverse linear\ndimensions $<X^2> - <X>^2$, $<R_{g,\\bot}^2>$ are used.",
        "positive": "Orientational wetting and topological transitions in confined solutions\n  of semi-flexible polymers: Despite their considerable practical and biological applications, the link\nbetween molecular properties, assembly conditions and self-organized structure\nin confined polymer solutions remains elusive. Here, we explore the lyotropic\nnematic ordering of semi-flexible chains in spherical confinement for multiple\ncontour lengths across a wide regime of concentrations. We uncover an original\ncrossover from two distinct quadrupolar states, both characterized by regular\ntetrahedral patterns of surface topological defects, to either longitudinal,\nlatitudinal or spontaneously-twisted bipolar structures with increasing\ndensities. These transitions, along with the intermediary arrangements that\nthey involve, are attributed to the combination of orientational wetting with\nsubtle variations in their liquid-crystal (LC) elastic anisotropies. Our\nmolecular simulations are corroborated by density functional calculations, and\nare quantified through the introduction of several order parameters as well as\nan unsupervised learning scheme for the localization of topological defects.\nOur results agree quantitatively with the predictions of continuum nematic\nelasticity theories, and evidence the extent to which the folding of\nmacromolecules and the self-assembly of low-molecular-weight LCs may be guided\nby the same, universal principles."
    },
    {
        "anchor": "Structure-property relationships of elastin-like polypeptides -- a\n  review of experimental and computational studies: Elastin is a structural protein with outstanding mechanical properties (e.g.,\nelasticity and resilience) and biologically relevant functions (e.g.,\ntriggering responses like cell adhesion or chemotaxis). It is formed from its\nprecursor tropoelastin, a 60-72 kDa water-soluble and temperature-responsive\nprotein that coacervates at physiological temperature, undergoing a phenomenon\ntermed lower critical solution temperature (LCST). Inspired by this behaviour,\nmany scientists and engineers are developing recombinantly produced\nelastin-inspired biopolymers, usually termed elastin-like polypeptides (ELPs).\nThese ELPs are generally comprised of repetitive motifs with the sequence\nVPGXG, which corresponds to repeats of a small part of the tropoelastin\nsequence, X being any amino acid except proline. ELPs display LCST and\nmechanical properties similar to tropoelastin, which renders them promising\ncandidates for the development of elastic and stimuli-responsive protein-based\nmaterials. Unveiling the structure-property relationships of ELPs can aid in\nthe development of these materials by establishing the connections between the\nELP amino acid sequence and the macroscopic properties of the materials. Here\nwe present a review of the structure-property relationships of ELPs and\nELP-based materials, with a focus on LCST and mechanical properties and how\nexperimental and computational studies have aided in their understanding.",
        "positive": "Electrolyte solutions at heterogeneously charged substrates: The influence of a chemically or electrically heterogeneous distribution of\ninteraction sites at a planar substrate on the number density of an adjacent\nfluid is studied by means of classical density functional theory (DFT). In the\ncase of electrolyte solutions the effect of this heterogeneity is particularly\nlong ranged, because the corresponding relevant length scale is set by the\nDebye length which is large compared to molecular sizes. The DFT used here\ntakes the solvent particles explicitly into account and thus captures\nphenomena, inter alia, due to ion-solvent coupling. The present approach\nprovides closed analytic expressions describing the influence of chemically and\nelectrically nonuniform walls. The analysis of isolated \\delta-like\ninteractions, isolated interaction patches, and hexagonal periodic\ndistributions of interaction sites reveals a sensitive dependence of the fluid\ndensity profiles on the type of the interaction, as well as on the size and the\nlateral distribution of the interaction sites."
    },
    {
        "anchor": "Stiff-Glass Approximation of Mode-Coupling Theory: The stiff-glass approximation of the mode-coupling theory of the\nglass-transition--as introduced in a recent paper by G\\\"otze and Mayr for a\ndiscussion of phenomena resembling the Boson Peak and High-Frequency Sound\nobservations made in real glass-formers--is examined in detail. It amounts to a\nneglection of two-phonon processes and thus provides a clear physical picture\nfor the MCT solutions deep in the glass. In addition, the effect of additional\nsymplifying approximations and the combination of these approximations is\nstudied.",
        "positive": "Ordering kinetics of stripe patterns: We study domain coarsening of two dimensional stripe patterns by numerically\nsolving the Swift-Hohenberg model of Rayleigh-Benard convection. Near the\nbifurcation threshold, the evolution of disordered configurations is dominated\nby grain boundary motion through a background of largely immobile curved\nstripes. A numerical study of the distribution of local stripe curvatures, of\nthe structure factor of the order parameter, and a finite size scaling analysis\nof the grain boundary perimeter, suggest that the linear scale of the structure\ngrows as a power law of time with a craracteristic exponent z=3. We interpret\ntheoretically the exponent z=3 from the law of grain boundary motion."
    },
    {
        "anchor": "Characterization of the gelation and resulting network of a\n  mixed-protein gel derived from sodium caseinate and ovalbumin in the presence\n  of glucono-$\u03b4$-lactone: We investigated mixed-protein gels made from sodium caseinate and ovalbumin\nat different ratios with use of the acidification agent\nglucono-$\\delta$-lactone. Dynamic viscoelastic measurements revealed that\nincreasing the ovalbumin content decreased the mechanical properties of the gel\nbut accelerated onset time of the phase transition. Ultrasound spectroscopy\nduring gelation revealed that the relative velocity gradually decreased,\nwhereas the ultrasonic attenuation increased during the whole acidification\nprocess until gelation was complete, although these changes were much smaller\nthan those observed with heat-induced gelation. Confocal laser scanning\nmicroscopy along with scanning electron microscopy revealed that although\nuniform mixing of sodium caseinate and ovalbumin was observed, sodium caseinate\nis likely to mainly lead formation of the gel network, and the porosity of the\nresulting gel network depends on the ratio of these two components. The results\ndemonstrate that confocal laser scanning microscopy is a useful tool for\nanalyzing both the networks within mixed-protein gels and the contribution of\neach protein to the network and gelation.",
        "positive": "Active colloidal suspensions exhibit polar order under gravity: This paper has been withdrawn."
    },
    {
        "anchor": "Viscous dynamics of drops and bubbles in Hele-Shaw cells: drainage, drag\n  friction, coalescence, and bursting: In this review article, we discuss recent studies on drops and bubbles in\nHele-Shaw cells, focusing on how scaling laws exhibit crossovers from the\nthree-dimensional counterparts and focusing on topics in which viscosity plays\nan important role. By virtue of progresses in analytical theory and high-speed\nimaging, dynamics of drops and bubbles have actively been studied with the aid\nof scaling arguments. However, compared with three dimensional problems,\nstudies on the corresponding problems in Hele-Shaw cells are still limited.\nThis review demonstrates that the effect of confinement in the Hele-Shaw cell\nintroduces new physics allowing different scaling regimes to appear. For this\npurpose, we discuss various examples that are potentially important for\nindustrial applications handling drops and bubbles in confined spaces by\nshowing agreement between experiments and scaling theories. As a result, this\nreview provides a collection of problems in hydrodynamics that may be\nanalytically solved or that may be worth studying numerically in the near\nfuture.",
        "positive": "Flow rule of dense granular flows down a rough incline: We present experimental findings on the flow rule for granular flows on a\nrough inclined plane using various materials including sand and glass beads of\nvarious sizes and four types of copper particles with different shapes. We\ncharacterize the materials by measuring $h_s$ (the thickness at which the flow\nsubsides) as a function of the plane inclination $\\theta$ on various surfaces.\nMeasuring the surface velocity $u$ of the flow as a function of flow thickness\n$h$, we find that for sand and glass beads the Pouliquen flow rule $u/\\sqrt{gh}\n\\sim \\beta h/h_s$ provides reasonable but not perfect collapse of the $u(h)$\ncurves measured for various $\\theta$ and mean particle diameter $d$. Improved\ncollapse is obtained for sand and glass beads by using a recently proposed\nscaling of the form $u/\\sqrt{gh} =\\beta \\cdot h \\tan^2\\theta /h_s\\\n\\tan^2\\theta_1$ where $\\theta_1$ is the angle at which the $h_s(\\theta)$ curves\ndiverge. Measuring the slope $\\beta$ for ten different sizes of sand and glass\nbeads, we find a systematic, strong increase of $\\beta$ with the divergence\nangle $\\theta_1$ of $h_s$. The copper materials with different shapes are not\nwell described by either flow rule with $u \\sim h^{3/2}$."
    },
    {
        "anchor": "The computational evidence for the crucial role of the dipole\n  cross-correlations in the polar glass-forming liquids: In this letter, we analyze the dipole-dipole correlations obtained from the\nmolecular dynamics simulations for strongly- and weakly-polar model liquids. As\na result, we found that cross-correlations contribution to the systems total\ndipole moment correlation function, which is directly measured in the\ndielectric spectroscopy experiment, is negligible for weakly-polar liquids. In\ncontrast, the cross-correlations term dominates over the self-correlations one\nfor examined strongly polar-liquid. Consequently, our studies strongly support\nthe interpretation of the dielectric spectra nature of the glass forming\nliquids, recently proposed by Pabst et al.",
        "positive": "Spatiotemporal heterogeneity of local free volumes in highly supercooled\n  liquid: We discuss the spatiotemporal behavior of local density and its relation to\ndynamical heterogeneity in a highly supercooled liquid by using molecular\ndynamics simulations of a binary mixture with different particle sizes in two\ndimensions. To trace voids heterogeneously existing with lower local densities,\nwhich move along with the structural relaxation, we employ the minimum local\ndensity for each particle in a time window whose width is set along with the\nstructural relaxation time. Particles subject to free volumes correspond well\nto the configuration rearranging region of dynamical heterogeneity. While the\ncorrelation length for dynamical heterogeneity grows with temperature decrease,\nno growth in the correlation length of heterogeneity in the minimum local\ndensity distribution takes place. A comparison of these results with those of\nnormal mode analysis reveals that superpositions of lower-frequency soft modes\nextending over the free volumes exhibit spatial correlation with the broken\nbonds. This observation suggests a possibility that long-ranged vibration modes\nfacilitate the interactions between fragile regions represented by free\nvolumes, to induce dynamical correlations at a large scale."
    },
    {
        "anchor": "Computational investigation of multivalent binding of a ligand coated\n  particle: Role of shape, size and ligand heterogeneity from a free energy\n  landscape perspective: We utilize a multiscale modeling framework to study the effect of shape, size\nand ligand composition on the efficacy of binding of a ligand-coated-particle\nto a substrate functionalized with the target receptors. First, we show how\nmolecular dynamics (MD) along with Steered MD calculations can be used to\naccurately parameterize the molecular binding free energy and the effective\nspring constant for a receptor-ligand pair. We demonstrate this for two ligands\nthat bind to the $\\alpha_5\\beta_1$-domain of integrin. Next, we show how these\neffective potentials can be used to build computational models at the meso- and\ncontinuum- scales. These models incorporate the molecular nature of the\nreceptor-ligand interactions and yet provide an inexpensive route to study the\nmultivalent interaction of receptors and ligands through the construction of\nBell potentials customized to the molecular identities. We quantify the binding\nefficacy of the ligand-coated-particle in terms of its multivalency, binding\nfree energy landscape and the losses in the configurational entropies. We show\nthat (i) the binding avidity for particle sizes less than $350$ nm is set by\nthe competition between the enthalpic and entropic contributions while that for\nsizes above $350$ nm is dominated by the enthalpy of binding, (ii) anisotropic\nparticles display higher multivalent binding compared to spherical particles\nand (iii) variations in ligand composition can alter binding avidity without\naltering the average multivalency. The methods and results presented here have\nwide applications in the rational design of functionalized carriers and also in\nunderstanding cell adhesion.",
        "positive": "Spatiotemporal Organization of Electromechanical Phase Singularities\n  during High-Frequency Cardiac Arrhythmias: Ventricular fibrillation (VF) is a lifethreatening electromechanical\ndysfunction of the heart associated with complex spatiotemporal dynamics of\nelectrical excitation and mechanical contraction of the heart muscle. It has\nbeen hypothesized that VF is driven by three-dimensional (3D) rotating\nelectrical scroll waves, which can be characterized by filament-like electrical\nphase singularities (EPS). Recently, it was shown that rotating excitation\nwaves during VF are associated with rotating waves of mechanical deformation.\n3D mechanical scroll waves and mechanical filaments describing their rotational\ncore were observed in the ventricles by using high-resolution ultrasound. The\nfindings suggest that the spatiotemporal organization of cardiac fibrillation\nmay be assessed from waves of mechanical deformation. However, the complex\nrelationship between excitation and mechanical waves during VF is currently not\nunderstood. Here, we study the fundamental nature of mechanical phase\nsingularities (MPS), their spatiotemporal organization and relation with EPS.\nWe demonstrate the existence of two fundamental types of MPS: \"paired\nsingularities\", which are co-localized with EPS, and \"unpaired singularities\",\nwhich can form independently. We show that the unpaired singularities emerge\ndue to the anisotropy of the active force field, generated by fiber anisotropy\nin cardiac tissue, and the non-locality of elastic interactions, which jointly\ninduce strong spatiotemporal inhomogeneities in the strain fields. The\ninhomogeneities lead to the breakup of deformation waves and create MPS, even\nin the absence of EPS, which are typically associated with excitation wave\nbreak. We exploit these insights to develop an approach to discriminate paired\nand unpaired MPS. Our findings provide a fundamental understanding of the\ncomplex spatiotemporal organization of electromechanical waves in the heart."
    },
    {
        "anchor": "Dynamics of Suspended Nanoparticles in a Time-varying Gradient Magnetic\n  Field: Analytical Results: We study theoretically the deterministic dynamics of single-domain\nferromagnetic nanoparticles in dilute ferrofluids, which is induced by a\ntime-varying gradient magnetic field. Using the force and torque balance\nequations, we derive a set of the first-order differential equations describing\nthe translational and rotational motions of such particles characterized by\nsmall Reynolds numbers. Since the gradient magnetic field generates both the\ntranslations and rotations of particles, these motions are coupled. Based on\nthe derived set of equations, we demonstrate this fact explicitly by expressing\nthe particle position through the particle orientation angle, and vice versa.\nThe obtained expressions are used to show that the solution of the basic set of\nequations is periodic in time and to determine the intervals, where the\nparticle coordinate and orientation angle oscillate. In addition, this set of\nequations is solved approximately for the case of small characteristic\nfrequency of the particle oscillations. With this condition, we find that all\nparticles perform small translational oscillations near their initial\npositions. In contrast, the orientation angle oscillates near the initial angle\nonly if particles are located in the vicinity of zero point of the gradient\nmagnetic field. The possible applications of the obtained results in\nbiomedicine and separation processes are also discussed.",
        "positive": "Role of particle local curvature in cellular wrapping: Cellular uptake through the lipid membranes plays an important role in\nadsorbing nutrients and fighting infection and can be used for drug delivery\nand nanomedicine developments. Endocytosis is one of the known pathways of the\ncellular uptake which associate with elastic deformation of the membrane\nwrapping around the foreign particle. The deformability of the membrane itself\nis strongly regulated by the presence of a cortical cytoskeleton placed\nunderneath the membrane. It has been shown that size, shape, and orientation of\nthe particles influence on their entry into the cell. Here, we study the role\nof particle local curvature in the cellular uptake by investigating the\nwrapping of an elastic membrane around a long cylindrical object with an\nelliptical cross section. The membrane itself is adhered to a substrate\nmimicking the cytoskeleton. Membrane wrapping proceeds differently whether the\ninitial contact occurs at the particle's highly curved tip (prolate) or along\nits long side (oblate). We obtain a wrapping phase diagram as a function of the\nmembrane-cytoskeleton and the membrane-target adhesion energy, which includes\nthree distinct regimes of engulfment(unwrapped, partially wrapped, and fully\nwrapped), separated by two phase transitions. We also provide analytical\nexpressions for the boundary between the different regimes which confirm that\nthe transitions strongly depend on the orientation and aspect ratio of the\nparticle."
    },
    {
        "anchor": "Measuring Colloidal Forces from Particle Position Deviations inside an\n  Optical Trap: We measure interaction forces between pairs of charged PMMA colloidal\nparticles suspended in a relatively low-polar medium (5 $\\lesssim \\epsilon\n\\lesssim$ 8) directly from the deviations of particle positions inside two\ntime-shared optical traps. The particles are confined to optical point traps;\none is held in a stationary trap and the other particle is brought closer in\nsmall steps while tracking the particle positions using confocal microscopy.\nFrom the observed particle positions inside the traps we calculate the\ninterparticle forces using an ensemble-averaged particle displacement-force\nrelationship. The force measurements are confirmed by independent measurements\nof the different parameters using electrophoresis and a scaling law for the\nliquid-solid phase transition. When increasing the salt concentration by\nexposing the sample to UV light, the force measurements agree well with the\nclassical DLVO theory assuming a constant surface potential. On the other hand,\nwhen adding tetrabutylammonium chloride (TBAC) to vary the salt concentration,\nsurface charge regulation seems to play an important role.",
        "positive": "Nonequilibrium Thermodynamics of the Soft Glassy Rheology Model: The Soft Glassy Rheology (SGR) model is a mesoscopic framework which proved\nto be very successful in describing flow and deformation of various amorphous\nmaterials phenomenologically (e.g. pastes, slurries, foams etc). In this paper,\nwe cast SGR in a general, model independent framework for nonequilibrium\nthermodynamics called General Equation for the Nonequilibrium\nReversible-Irreversible Coupling (GENERIC). This leads to a new formulation of\nSGR which clarifies how it can properly be coupled to hydrodynamic fields,\nresulting in a thermodynamically consistent, local, continuum version of SGR.\nAdditionally, we find that compliance with thermodynamics imposes the existence\nof a modification to the stress tensor as predicted by SGR."
    },
    {
        "anchor": "Electrostatic pair-interaction of nearby metal or metal-coated colloids\n  at fluid interfaces: In this paper, we theoretically study the electrostatic interaction between a\npair of identical colloids with constant surface potentials sitting in close\nvicinity of each other at a fluid interface. By employing a simplified yet\nreasonable model system, the problem is solved within the framework of\nclassical density functional theory and linearized as well as nonlinear\nPoisson-Boltzmann (PB) theory. Apart from providing a sound theoretical\nframework generally applicable to any such problem, our novel findings, all of\nwhich contradict common beliefs, include the following: first, quantitative as\nwell as qualitative differences between the interactions obtained within the\nlinear and the nonlinear PB theories; second, the importance of the\nelectrostatic interaction between the omnipresent three-phase contact lines in\ninterfacial systems; and third, the occurrence of an attractive electrostatic\ninteraction between a pair of identical metal colloids. The unusual attraction\nwe report on largely stems from an attractive line interaction which although\nscales linearly with the size of the particle, can compete with the surface\ninteractions and can be strong enough to alter the nature of the total\nelectrostatic interaction. Our results should find applications in metal or\nmetal-coated particle-stabilized emulsions where densely packed particle arrays\nare not only frequently observed but are sometimes required.",
        "positive": "Atomistic simulation of structure and dynamics of columnar phases of\n  hexabenzocoronene derivatives: Using atomistic molecular dynamics simulations we study solid and liquid\ncrystalline columnar discotic phases formed by alkyl-substituted\nhexabenzocoronene mesogens. Correlations between the molecular structure,\npacking, and dynamical properties of these materials are established."
    },
    {
        "anchor": "Arrested state of clay-water suspensions: gel or glass?: The aging of a charged colloidal system has been studied by Small Angle\nX-rays Scattering, in the exchanged momentum range Q=0.03 - 5 nm-1, and by\nDynamic Light Scattering, at different clay concentrations (Cw =0.6 % - 2.8 %).\nThe static structure factor, S(Q), has been determined as a function of both\naging time and concentration. This is the first direct experimental evidence of\nthe existence and evolution with aging time of two different arrested states in\na single system simply obtained only by changing its volume fraction: an\ninhomogeneous state is reached at low concentrations, while a homogenous one is\nfound at high concentrations.",
        "positive": "Crack front instabilities under mixed mode loading in three dimensions: The evolution of a crack front under mixed mode loading (I+III) is studied\nusing a phase field model in 3 dimensions with no stress boundary conditions.\nAs previously observed experimentally in gels, there is a relaxation toward a\ngeometry where $K_{III}=0$ without any front fragmentation even for high values\nof the initial mode mixity $K_{III}/K_{I}$. The effects of the initial\ncondition is studied and it is shown that irregularities in the initial slit\ncan lead to front fragmentation for smaller values of the ratio $K_{III}/K_{I}$\nas is observed in experiments."
    },
    {
        "anchor": "Kinetic Properties of a Bose-Einstein Gas at Finite Temperature: We study, in the framework of the Boltzmann-Nordheim equation (BNE), the\nkinetic properties of a boson gas above the Bose-Einstein transition\ntemperature $T_c$. The BNE is solved numerically within a new algorithm, that\nhas been tested with exact analytical results for the collision rate of an\nhomogeneous system in thermal equilibrium. In the classical regime ($T > 6~\nT_c$), the relaxation time of a quadrupolar deformation in momentum space is\nproportional to the mean free collision time $\\tau_{relax} \\sim T^{-1/2}$.\nApproaching the critical temperature ($T_c < T < 2.7~ T_c$), quantum statistic\neffects in BNE become dominant, and the collision rate increases dramatically.\nNevertheless, this does not affect the relaxation properties of the gas that\ndepend only on the spontaneous collision term in BNE. The relaxation time\n$\\tau_{relax}$ is proportional to $(T - T_c)^{-1/2}$, exhibiting a critical\nslowing down. These phenomena can be experimentally confirmed looking at the\ndamping properties of collective motions induced on trapped atoms. The\npossibility to observe a transition from collisionless (zero-sound) to\nhydrodynamic (first-sound) is finally discussed.",
        "positive": "Theory of self-assembled smectic-A \"crenellated disks\": Smectic-A monolayers self-assembled in aqueous solutions of chiral fd viruses\nand a polymer depletant have been shown to exhibit a variety of structures\nincluding large, flat disks and twisted ribbons. The virus particles twist near\nthe edge of the structure in a direction determined by the chirality of the\nviruses. When fd viruses and their mutants of opposite chirality are mixed\ntogether in nearly equal amounts unusual structures referred to as \"crenellated\ndisks\" can appear. These disks are achiral overall but the twist at the edge\nalternates between left- and right-handedness. To minimize the mismatch where\nthe two regions of opposing twist meet, the \"crenellated\" structure exhibits\ncusps rising out of the plane of the monolayer. We use a phenomenological\nelastic theory previously applied to flat disks and twisted ribbons to analyze\nan analytic model proposed to describe the \"crenellated\" structure . When\ncompared with flat, circular disks, we find that the model \"crenellated disks\"\nare stable or at least metastable in a wide region of the phase diagram spanned\nby the Gaussian curvature modulus and the edge energy modulus, with a large\nenergy barrier separating the two structures. The director pattern and\ngeometric parameters of the \"crenellated disks\" are found to be in qualitative\nagreement with experimental observations."
    },
    {
        "anchor": "Interstitials, Vacancies and Dislocations in Flux-Line Lattices: A\n  Theory of Vortex Crystals, Supersolids and Liquids: We study a three dimensional Abrikosov vortex lattice in the presence of an\nequilibrium concentration of vacancy, interstitial and dislocation loops.\nVacancies and interstitials renormalize the long-wavelength bulk and tilt\nelastic moduli. Dislocation loops lead to the vanishing of the long-wavelength\nshear modulus. The coupling to vacancies and interstitials - which are always\npresent in the liquid state - allows dislocations to relax stresses by climbing\nout of their glide plane. Surprisingly, this mechanism does not yield any\nfurther independent renormalization of the tilt and compressional moduli at\nlong wavelengths. The long wavelength properties of the resulting state are\nformally identical to that of the ``flux-line hexatic'' that is a candidate\n``normal'' hexatically ordered vortex liquid state.",
        "positive": "Diffusion NMR Methods Applied to Xenon Gas for Materials Study: We report initial NMR studies of i) xenon gas diffusion in model\nheterogeneous porous media, and ii) continuous flow laser-polarized xenon gas.\nBoth areas utilize the Pulsed Gradient Spin Echo techniques in the gas-phase,\nwith the aim of obtaining more sophisticated information than just\ntranslational self-diffusion coefficients - a brief overview of this area is\nprovided in the introduction. The heterogeneous or multiple-length scale model\nporous media consisted of random packs of mixed glass beads of two different\nsizes. We focus on observing the approach of the time-dependent gas diffusion\ncoefficient, D(t), (an indicator of mean squared displacement) to the long-time\nasymptote, with the aim of understanding the long-length scale structural\ninformation that may be derived from a heterogeneous porous system. The Pade\napproximation is used to interpolate D(t) data between the short and long time\nlimits. Initial studies of continuous flow laser-polarized xenon gas\ndemonstrate velocity-sensitive imaging of much higher flows than can generally\nbe obtained with liquids (20 - 200 mm/s). Gas velocity imaging is, however,\nfound to be limited to a resolution of about 1 mm/s due to the high diffusivity\nof gases compared to liquids. We also present the first gas-phase NMR\nscattering, or diffusive-diffraction, data: namely, flow-enhanced structural\nfeatures in the echo attenuation data from laser-polarized xenon flowing\nthrough a 2 mm glass bead pack."
    },
    {
        "anchor": "Films of bacteria at interfaces: three stages of behaviour: Bacterial attachment to a fluid interface can lead to the formation of a film\nwith physicochemical properties that evolve with time. We study the time\nevolution of interface (micro)mechanics for interfaces between oil and\nbacterial suspensions by following the motion of colloidal probes trapped by\ncapillarity to determine the interface microrheology. Initially, active\nbacteria at and near the interface drive superdiffusive motion of the colloidal\nprobes. Over timescales of minutes, the bacteria form a viscoelastic film which\nwe discuss as a quasi-two-dimensional, active, glassy system. To study late\nstage mechanics of the film, we use pendant drop elastometry. The films, grown\nover tens of hours on oil drops, are expanded and compressed by changing the\ndrop volume. For small strains, by modeling the films as 2D Hookean solids, we\nestimate the film elastic moduli, finding values similar to those reported in\nthe literature for the bacteria themselves. For large strains, the films are\nhighly hysteretic. Finally, from wrinkles formed on highly compressed drops, we\nestimate film bending energies. The dramatic restructuring of the interface by\nsuch robust films has broad implications, e.g. in the study of active colloids,\nin understanding the community dynamics of bacteria, and in applied settings\nincluding bioremediation.",
        "positive": "Bubble Relaxation Dynamics in Double-Stranded DNA: The paper deals with the two-state (opening-closing of base pairs) model used\nto describe the fluctuation dynamics of a single bubble formation. We present\nan exact solution for the discrete and finite size version of the model that\nincludes end effects and derive analytic expressions of the correlation\nfunction, survival probability and lifetimes for the bubble relaxation\ndynamics. It is shown that the continuous and semi-infinite limit of the model\nbecomes a good approximation to exact result when a^N << 1, where N is bubble\nsize and a, the ratio of opening to closing rates of base pairs, is the control\nparameter of DNA melting."
    },
    {
        "anchor": "Molecular dynamics simulation study of self-diffusion for\n  penetrable-sphere model fluids: Molecular dynamics simulations are carried out to investigate the diffusion\nbehavior of penetrable-sphere model fluids characterized by a finite energy\nbarrier $\\epsilon$. The self-diffusion coefficient is evaluated from the\ntime-dependent velocity autocorrelation function and mean-square displacement.\nDetailed insights into the cluster formation for penetrable spheres are gained\nfrom the Enskog factor, the effective particle volume fraction, the mean free\npath, and the collision frequency for both the soft-type penetrable and the\nhard-type reflective collisions. The simulation data are compared to\ntheoretical predictions from the Boltzmann kinetic equation and from a simple\nextension to finite $\\epsilon$ of the Enskog prediction for impenetrable hard\nspheres ($\\epsilon\\to\\infty$). A reasonable agreement between theoretical and\nsimulation results is found in the cases of $\\epsilon^*\\equiv\n\\epsilon/k_BT=0.2$, $0.5$, and $1.0$. However, for dense systems (packing\nfraction $\\phi>0.6$) with a highly repulsive energy barrier ($\\epsilon^*=3.0$),\na poorer agreement was observed due to metastable static effects of clustering\nformation and dynamic effects of correlated collision processes among these\ncluster-forming particles.",
        "positive": "Simple Model of Membrane Proteins Including Solvent: We report a numerical simulation for the phase diagram of a simple two\ndimensional model, similar to one proposed by Noro and Frenkel [J. Chem. Phys.\n\\textbf{114}, 2477 (2001)] for membrane proteins, but one that includes the\nrole of the solvent. We first use Gibbs ensemble Monte Caro simulations to\ndetermine the phase behavior of particles interacting via a square-well\npotential in two dimensions for various values of the interaction range. A\nphenomenological model for the solute-solvent interactions is then studied to\nunderstand how the fluid-fluid coexistence curve is modified by solute-solvent\ninteractions. It is shown that such a model can yield systems with\nliquid-liquid phase separation curves that have both upper and lower critical\npoints, as well as closed loop phase diagrams, as is the case with the\ncorresponding three dimensional model."
    },
    {
        "anchor": "Spontaneous polarization in an interfacial growth model for actin\n  filament networks with a rigorous mechano-chemical coupling: Many processes in eukaryotic cells, including cell motility, rely on the\ngrowth of branched actin networks from surfaces. Despite its central role the\nmechano-chemical coupling mechanisms which guide the growth process are poorly\nunderstood, and a general continuum description combining growth and mechanics\nis lacking. We develop a theory that bridges the gap between mesoscale and\ncontinuum limit and propose a general framework providing the evolution law of\nactin networks growing under stress. This formulation opens an area for the\nsystematic study of actin dynamics in arbitrary geometries. Our framework\npredicts a morphological instability of actin growth on a rigid sphere, leading\nto a spontaneous polarization of the network with a mode selection\ncorresponding to a comet, as reported experimentally. We show that the\nmechanics of the contact between the network and the surface plays a crucial\nrole, in that it determines directly the existence of the instability. We\nextract scaling laws relating growth dynamics and network properties offering\nbasic perspectives for new experiments on growing actin networks.",
        "positive": "Revisiting the Second Vassiliev (In)variant for Polymer Knots: Knots in open strands such as ropes, fibers, and polymers, cannot typically\nbe described in the language of knot theory, which characterizes only closed\ncurves in space. Simulations of open knotted polymer chains, often\nparameterized to DNA, typically perform a closure operation and calculate the\nAlexander polynomial to assign a knot topology. This is limited in scenarios\nwhere the topology is less well-defined, for example when the chain is in the\nprocess of untying or is strongly confined. Here, we use a discretized version\nof the Second Vassiliev Invariant for open chains to analyze Langevin Dynamics\nsimulations of untying and strongly confined polymer chains. We demonstrate\nthat the Vassiliev parameter can accurately and efficiently characterize the\nknotted state of polymers, providing additional information not captured by a\nsingle-closure Alexander calculation. We discuss its relative strengths and\nweaknesses compared to standard techniques, and argue that it is a useful and\npowerful tool for analyzing polymer knot simulations."
    },
    {
        "anchor": "Lengthscales and Cooperativity in DNA Bubble Formation: It appears that thermally activated DNA bubbles of different sizes play\ncentral roles in important genetic processes. Here we show that the probability\nfor the formation of such bubbles is regulated by the number of soft AT pairs\nin specific regions with lengths which at physiological temperatures are of the\norder of (but not equal to) the size of the bubble. The analysis is based on\nthe Peyrard- Bishop-Dauxois model, whose equilibrium statistical properties\nhave been accurately calculated here with a transfer integral approach.",
        "positive": "Relaxation dynamics in a binary hard-ellipse liquid: Structural relaxation in binary hard spherical particles has been shown\nrecently to exhibit a wealth of remarkable features when size disparity or\nmixture's composition is varied. In this paper, we test whether or not similar\ndynamical phenomena occur in glassy systems composed of binary hard ellipses.\nWe demonstrate via event-driven molecular dynamics simulation that a binary\nhard-ellipse mixture with an aspect ratio of two and moderate size disparity\ndisplays characteristic glassy dynamics upon increasing density in both the\ntranslational and the rotational degrees of freedom. The rotational glass\ntransition density is found to be close to the translational one for the binary\nmixtures investigated. More importantly, we assess the influence of size\ndisparity and mixture's composition on the relaxation dynamics. We find that an\nincrease of size disparity leads, both translationally and rotationally, to a\nspeed up of the long-time dynamics in the supercooled regime so that both the\ntranslational and the rotational glass transition shift to higher densities. By\nincreasing the number concentration of the small particles, the time evolution\nof both translational and rotational relaxation dynamics at high densities\ndisplays two qualitatively different scenarios, i.e., both the initial and the\nfinal part of the structural relaxation slow down for small size disparity,\nwhile the short-time dynamics still slows down but the final decay speeds up in\nthe binary mixture with large size disparity. These findings are reminiscent of\nthose observed in binary hard spherical particles. Therefore, our results\nsuggest a universal mechanism for the influence of size disparity and mixture's\ncomposition on the structural relaxation in both isotropic and anisotropic\nparticle systems."
    },
    {
        "anchor": "Unconventional ordering behavior of semi-flexible polymers in dense\n  brushes under compression: Using a coarse-grained bead-spring model for semi-flexible macromolecules\nforming a polymer brush, structure and dynamics of the polymers is\ninvestigated, varying chain stiffness and grafting density. The anchoring\ncondition for the grafted chains is chosen such that their first bonds are\noriented along the normal to the substrate plane.\n  Compression of such a semi-flexible brush by a planar piston is observed to\nbe a two-stage process: for small compressions the chains contract by\n\"buckling\" deformation whereas for larger compression the chains exhibit a\ncollective (almost uniform) bending deformation. Thus, the stiff polymer brush\nundergoes a 2-nd order phase transition of collective bond reorientation. The\npressure, required to keep the stiff brush at a given degree of compression, is\nthereby significantly smaller than for an otherwise identical brush made of\nentirely flexible polymer chains! While both the brush height and the chain\nlinear dimension in the z-direction perpendicular to the substrate increase\nmonotonically with increasing chain stiffness, lateral (xy) chain linear\ndimensions exhibit a maximum at intermediate chain stiffness. Increasing the\ngrafting density leads to a strong decrease of these lateral dimensions,\ncompatible with an exponential decay. Also the recovery kinetics after removal\nof the compressing piston is studied, and found to follow a power-law /\nexponential decay with time.\n  A simple mean-field theoretical consideration, accounting for the\nbuckling/bending behavior of semi-flexible polymer brushes under compression,\nis suggested.",
        "positive": "Geometric transformation and three-dimensional hopping of Hopf solitons: 3D topological solitons are marvels of mathematical physics that arise in\ntheoretical models in elementary particle and nuclear physics, condensed\nmatter, and cosmology. A particularly interesting type of them is described by\nthe mathematical Hopf map from a hypersphere to an ordinary sphere, which in\nthe physical 3D space exhibits inter-linked circle-like or knotted localized\nregions of constant order parameter values. Despite their prevalence in models,\nsuch solitons remained experimentally elusive until recently, when hopfions\nwere discovered in colloids and chiral liquid crystals, whereas the so-called\n\"heliknotons\" were found both individually and within triclinic 3D lattices\nwhile smoothly embedded in a helical background of chiral liquid crystals.\nConstrained by mathematical theorems, stability of these 3D excitations is\nthought to rely on a delicate interplay of competing free energy contributions,\nrequiring applied fields or confinement. Here we describe such 3D solitons in a\nmaterial system where no applied fields or confinement are required.\nNevertheless, electric fields allow for inter-transforming heliknotons and\nhopfions to each other, as well as for 3D hopping-like dynamics arising from\nnonreciprocal evolution of the molecular alignment field in response to\nelectric pulses. Stability of these solitons both in and out of equilibrium can\nbe enhanced by tuning anisotropy of parameters that describe energetic costs of\ngradient components in the field, which is implemented through varying chemical\ncomposition of liquid crystal mixtures. Numerical modelling reproduces fine\ndetails of both the equilibrium structure and Hof-index-preserving\nout-of-equilibrium evolution of the molecular alignment field during switching\nand motions. Our findings may enable myriads of solitonic condensed matter\nphases and active matter systems, as well as their technological applications."
    },
    {
        "anchor": "Intracellular microrheology of motile Amoeba proteus: The motility of motile Amoeba proteus was examined using the technique of\npassive particle tracking microrheology, with the aid of newly-developed\nparticle tracking software, a fast digital camera and an optical microscope. We\ntracked large numbers of endogeneous particles in the amoebae, which displayed\nsubdiffusive motion at short time scales, corresponding to thermal motion in a\nviscoelastic medium, and superdiffusive motion at long time scales due to the\nconvection of the cytoplasm. Subdiffusive motion was characterised by a\nrheological scaling exponent of 3/4 in the cortex, indicative of the\nsemiflexible dynamics of the actin fibres. We observed shear-thinning in the\nflowing endoplasm, where exponents increased with increasing flow rate; i.e.\nthe endoplasm became more fluid-like. The rheology of the cortex is found to be\nisotropic, reflecting an isotropic actin gel. A clear difference was seen\nbetween cortical and endoplasmic layers in terms of both viscoelasticity and\nflow velocity, where the profile of the latter is close to a Poiseuille flow\nfor a Newtonian fluid.",
        "positive": "Range and strength of mechanical interactions of force dipoles in\n  elastic fiber networks: Mechanical forces generated by myosin II molecular motors drive diverse\ncellular processes, most notably shape change, division and locomotion. These\nforces may be transmitted over long range through the cytoskeletal medium - a\ndisordered, viscoelastic network of biopolymers. The resulting cell size scale\nforce chains can in principle mediate mechanical interactions between distant\nactomyosin units, leading to self-organized structural order in the cell\ncytoskeleton. To investigate this process, we model the actin cytoskeleton on a\npercolated fiber lattice network, where fibers are modeled as linear elastic\nelements that can both bend and stretch, whereas myosin motors exert\ncontractile force dipoles. We quantify the range and heterogeneity of force\ntransmission in these networks in response to a force dipole, showing how these\ndepend on varying bond dilution and fiber bending-to-stretching stiffness\nratio. By analyzing clusters of nodes connected to highly strained bonds, as\nwell as the decay rate of strain energy with distance from the force dipole, we\nshow that long-range force transmission is screened out by fiber bending in\ndiluted networks. We further characterize the difference in the propagation of\ntensile and compressive forces. This leads to a dependence of the mechanical\ninteraction between a pair of force dipoles on their mutual separation and\norientation. In more homogeneous networks, the interaction between force\ndipoles recapitulates the power law dependence on separation distance predicted\nby continuum elasticity theory, while in diluted networks, the interactions are\nshort-ranged and fluctuate strongly with local network configurations.\nAltogether, our work suggests that elastic interactions between force dipoles\nin disordered, fibrous media can act as an organizing principle in biological\nmaterials."
    },
    {
        "anchor": "Probing Nanofriction and Aubry-type signatures in a finite\n  self-organized system: Friction in ordered atomistic layers plays a central role in various\nnanoscale systems ranging from nanomachines to biological systems. It governs\ntransport properties, wear and dissipation. Defects and incommensurate lattice\nconstants dramatically change these properties. Recently experimental systems\nhave become accessible to probe the dynamics of nanofriction. Here, we present\na model system consisting of laser-cooled ions in which nanofriction and\ntransport processes in self-organized systems with back action can be studied\nwith atomic resolution. We show that in a system with local defects resulting\nin incommensurate layers, there is a transition from sticking to sliding with\nAubry-type signatures. We demonstrate spectroscopic measurements of the soft\nvibrational mode driving this transition and a measurement of the order\nparameter. We show numerically that both exhibit critical scaling near the\ntransition point. Our studies demonstrate a simple, well-controlled system in\nwhich friction in self-organized structures can be studied from classical- to\nquantum-regimes.",
        "positive": "Quantum Theory of Chiral Interactions in Cholesteric Liquid Crystals: We study the effective chiral interaction between molecules arising from\nquantum dispersion interactions within a model in which a) the dominant excited\nstates of a molecule form a band whose width is small compared to the average\nexcitation energy and b) biaxial orientational correlation between adjacent\nmolecules can be neglected. Previous treatments of quantum chiral interactions\nwere based on a multipole expansion of the intermolecular interaction. However,\nbecause real liquid crystals are composed of elongated molecules, we utilize an\nexpansion in terms of only coordinates transverse to the long molecular axes.\nWe identify two distinct physical limits depending on whether one or both of\nthe interacting molecules are excited in the virtual state. When both molecules\nare excited, our results are similar to those found previously by van der Meer\net al. Previously unidentified terms in which only one molecule is excited\ninvolve the interactions of local dipole moments, which exist even when the\nglobal dipole moment of the molecule vanishes. We present analytic and\nnumerical results for helical molecules. Our results do not indicate whether\nthe dominant chiral interaction in cholesterics results from quantum or from\nsteric interactions."
    },
    {
        "anchor": "Surface instability in a nematic elastomer: Liquid crystal elastomers (LCEs) are soft phase-changing solids that exhibit\nlarge reversible contractions upon heating, Goldstone-like soft modes and\nresultant microstructural instabilities. We heat a planar LCE slab to\nisotropic, clamp the lower surface then cool back to nematic. Clamping prevents\nmacroscopic elongation, producing compression and microstructure. We see that\nthe free surface destabilizes, adopting topography with amplitude and\nwavelength similar to thickness. To understand the instability, we numerically\ncompute the microstructural relaxation of a \"non-ideal\" LCE energy. Linear\nstability reveals a Biot-like scale-free instability, but with oblique\nwavevector. However, simulation and experiment show that, unlike classic\nelastic creasing, instability culminates in a cross-hatch without cusps or\nhysteresis, and is constructed entirely from low-stress soft modes.",
        "positive": "Diffusion, phase behavior and gelation in a two-dimensional layer of\n  colloids in osmotic equilibrium with a polymer reservoir: The addition of enough non-adsorbing polymer to an otherwise stable colloidal\nsuspension gives rise to a variety of phase behavior and kinetic arrest due to\nthe depletion attraction induced between the colloids by the polymers. We\nreport a study of these phenomena in a two-dimensional layer of colloids. The\nthree-dimensional phenomenology of crystal-fluid coexistence is reproduced, but\ngelation takes a novel form, in which the strands in the gel structure are\nlocally crystalline. We compare our findings with a previous simulation and\ntheory, and find substantial agreement."
    },
    {
        "anchor": "Electron Transfer in Porphyrin Complexes in Different Solvents: The electron transfer in different solvents is investigated for systems\nconsisting of donor, bridge and acceptor. It is assumed that vibrational\nrelaxation is much faster than the electron transfer. Electron transfer rates\nand final populations of the acceptor state are calculated numerically and in\nan approximate fashion analytically. In wide parameter regimes these solutions\nare in very good agreement. The theory is applied to the electron transfer in\n${\\rm H_2P-ZnP-Q}$ with free-base porphyrin (${\\rm H_2P}$) being the donor,\nzinc porphyrin (${\\rm ZnP}$) the bridge, and quinone (${\\rm Q}$) the acceptor.\nIt is shown that the electron transfer rates can be controlled efficiently by\nchanging the energy of the bridging level which can be done by changing the\nsolvent. The effect of the solvent is determined for different models.",
        "positive": "Efficiency and current reversals in spatially inhomogeneous ratchets: Efficiency of generation of net unidirectional current in an adiabatically\ndriven symmetric periodic potential system is studied.\n  The efficiency shows a maximum, in the case of an inhomogeneous system with\nspatially varying periodic friction coefficient, as a function of temperature.\nThe ratchet is not most efficient when it gives maximum current. The direction\nof current may also be reversed as a function of noise strength when, instead,\nan asymmetric periodic potential is considered."
    },
    {
        "anchor": "Forced microrheology of active colloids: Particle-tracking microrheology of dilute active (self-propelled) colloidal\nsuspensions is studied by considering the external force required to maintain\nthe steady motion of an immersed constant-velocity colloidal probe. If the\nprobe speed is zero, the suspension microstructure is isotropic but exhibits a\nboundary accumulation of active bath particles at contact due to their\nself-propulsion. As the probe moves through the suspension, the microstructure\nis distorted from the nonequilibrium isotropic state, which allows us to define\na microviscosity for the suspension using the Stokes drag law. For a slow\nprobe, we show that active suspensions exhibit a swim-thinning behavior in\nwhich their microviscosity is gradually lowered from that of passive\nsuspensions as the swim speed increases. When the probe speed is fast, the\nsuspension activity is obscured by the rapid advection of the probe and the\nmeasured microviscosity is indistinguishable from that of passive suspensions.\nGenerally for finite activity, the suspension exhibits a velocity-thinning\nbehavior -- though with a zero-velocity plateau lower than passive suspensions\n-- as a function of the probe speed. These behaviors originate from the\ninterplay between the suspension activity and the hard-sphere excluded-volume\ninteraction between the probe and a bath particle.",
        "positive": "Polymers with self-attraction and stiffness: a generic phase structure: Recently it has been shown that a two-dimensional model of self-attracting\npolymers based on attracting segments displays two phase transitions, a\ntheta-like collapse between swollen polymers and a globular state and another\nbetween the globular state and a polymer crystal. On the other hand, the\ncanonical model based on attracting monomers on lattice sites displays only\none: the standard tricritical theta collapse transition. Here we show that by\nconsidering both models with the addition of stiffness the two models display\nthe same generic phase diagram. In fact we claim that any two-dimensional model\nof a self-attracting single polymer in solution based upon a fully\nvolume-excluded backbone with isotropic short range attraction should show this\nsame phase structure. We point to the model of hydrogen bonded polymers to\ndemonstrate this observation. In three dimensions we note that more than one\ncrystalline phase may occur."
    },
    {
        "anchor": "Temperature dependence study of water dynamics in Fluorohectorite clays\n  using Molecular dynamics simulations: In this work, we have carried out molecular dynamics (MD) simulation\ntechniques to study the diffusion coefficient of interlayer molecules at\ndifferent temperature. Within the wider context of water dynamics in soils, and\nwith a particular emphasis on clays, we present here the translational dynamics\nof water in clays, in a bi-hydrated states. We focus on temperatures between\n293 K and 350 K, i.e., the range relevant to the environmental waste packages.\nA natural hectorite clay of interest is modified as a synthetic clay, which\nallows us to understand the determinantal parameters from MD simulations\nthrough a comparison with the experimental values. The activation energy E a\ndetermined by our simulation is [8.50 - 16.62] KJ/mol. The calculated diffusive\nconstants are in the order of 10^{-5} {cm^{2}}/s. The simulation results are in\ngood agreement with experiments for the relevant set of conditions, and they\ngive more insight into the origin of the observed dynamics.",
        "positive": "Conformational transitions of a semiflexible polymer in nematic solvents: Conformations of a single semiflexible polymer chain dissolved in a low\nmolecular weight liquid crystalline solvents (nematogens) are examined by using\na mean field theory. We takes into account a stiffness and partial\norientational ordering of the polymer. As a result of an anisotropic coupling\nbetween the polymer and nematogen, we predict a discontinuous (or continuous)\nphase transition from a condensed-rodlike conformation to a swollen-one of the\npolymer chain, depending on the stiffness of the polymer. We also discuss the\neffects of the nematic interaction between polymer segments."
    },
    {
        "anchor": "Grand-canonical Monte-Carlo simulation of solutions of salt mixtures:\n  theory and implementation: A Grand-canonical Monte-Carlo simulation method extended to simulate a\nmixture of salts is presented. Due to charge neutrality requirement of\nelectrolyte solutions, ions must be added to or removed from the system in\ngroups. This leads to some complications compared to regular Grand Canonical\nsimulation. Here, a recipe for simulation of electrolyte solution of salt\nmixture is presented. It is then implemented to simulate solution of 1:1, 2:1\nand 2:2 salts or their mixtures at different concentrations using the primitive\nion model. The osmotic pressures of the electrolyte solutions are calculated\nand shown to depend linearly on the salt concentrations within the\nconcentration range simulated. We also show that at the same concentration of\ndivalent anions, the presence of divalent cations make it easier to insert\nmonovalent cations into the system. This can explain some quantitative\ndifferences observed in experiments of the MgCl$_2$ salt mixture and MgSO$_4$\nsalt mixture.",
        "positive": "Classical density functional theory for associating fluids in orienting\n  external fields: We develop a classical density functional theory (DFT) for two site\nassociating fluids in spatially uniform external fields which exhibit\norientational inhomogeneities. The Helmholtz free energy functional is obtain\nusing Wertheim's thermodynamic perturbation theory and the orientational\ndistribution function is obtained using DFT in the canonical ensemble. It is\nshown that an orienting field significantly enhances association by ordering\nthe molecules thereby reducing the entropic penalty of association. It is also\nshown that association enhances orientational order for fixed field strength."
    },
    {
        "anchor": "Structural similarity between dry and wet sphere packings: The mechanical properties of granular materials change significantly in the\npresence of a wetting liquid which creates capillary bridges between the\nparticles. Here we demonstrate, using X-ray tomographies of dry and wet sphere\npackings, that this change in mechanical properties is not accompanied by\nstructural differences between the packings. We characterize the latter by the\naverage numbers of contacts of each sphere $\\langle Z\\rangle$ and the shape\nisotropy $\\langle \\beta_0^{2,0} \\rangle$ of the Voronoi cells of the particles.\nAdditionally, we show that the number of liquid bridges per sphere $\\langle\nB\\rangle$ is approximately equal to $\\langle Z\\rangle + 2$, independent of the\nvolume fraction of the packing. These findings will be helpful in guiding the\ndevelopment of both particle-based models and continuum mechanical descriptions\nof wet granular matter.",
        "positive": "Rhombic preordering on a square substrate: A competition of incommensurate symmetries occurs whenever a system is forced\nto conform to an ordering that is different from the intrinsically preferred\nstructure of the system itself. As a model system of such a competition, we\nstudy the rivalry between the triangular ordering of hard disks and the square\nsymmetry induced by a periodic square substrate. By using density functional\ntheory as well as Monte Carlo computer simulations, we determine the full phase\nbehavior for the case of one particle per minimum. We observe a rhombic\npreordering structure preceding the hexagonal solid as a direct consequence of\nthe competing symmetries. Furthermore, the square-rhombic transition is\nreentrant with increasing substrate interaction. Our predictions can be\nverified in experiments of colloids in laser fields."
    },
    {
        "anchor": "Do cylinders exhibit a cubatic phase?: We investigate the possibility that freely rotating cylinders with an aspect\nratio $L/D=0.9$ exhibit a cubatic phase similar to the one found for a system\nof cut-spheres. We present theoretical arguments why a cubatic phase might\noccur in this particular system. Monte Carlo simulations do not confirm the\nexistence of a cubatic phase for cylinders. However, they do reveal an\nunexpected phase behavior between the isotropic and crystalline phase.",
        "positive": "A novel method for measuring electric field induced dipole moments of\n  metal-dielectric Janus particles in nematic liquid crystals: Janus particles are special types of nano or micro particles possessing at\nleast two surfaces with distinct physical or chemical properties. The most\nstudied Janus particles are the metal-dielectric particles, in which half\nsurface of dielectric particles is coated with a very thin layer of metals. The\nexternal electric field induces dipole moment, and consequently the particles\nexhibit self-assembled dynamic structures in concentrated aqueous suspensions.\nHere, we study metal-dielectric Janus particles in a nematic liquid crystal\nunder AC electric field and demonstrate a novel method for measuring effective\ninduced dipole moments of the particles, through competition between elastic\nand electrostatic (Coulomb) forces of the two particles. The calculated\npolarisability of the particles based on a simple model agrees well with the\neffective polarisability measured in the experiments. Our findings have\nimportant bearing on functional materials based on metal-dielectric Janus\nparticles dispersed in an anisotropic medium."
    },
    {
        "anchor": "Pattern Formation of Ion Channels with State Dependent Electrophoretic\n  Charges and Diffusion Constants in Fluid Membranes: A model of mobile, charged ion channels in a fluid membrane is studied. The\nchannels may switch between an open and a closed state according to a simple\ntwo-state kinetics with constant rates. The effective electrophoretic charge\nand the diffusion constant of the channels may be different in the closed and\nin the open state. The system is modeled by densities of channel species,\nobeying simple equations of electro-diffusion. The lateral transmembrane\nvoltage profile is determined from a cable-type equation. Bifurcations from the\nhomogeneous, stationary state appear as hard-mode, soft-mode or hard-mode\noscillatory transitions within physiologically reasonable ranges of model\nparameters. We study the dynamics beyond linear stability analysis and derive\nnon-linear evolution equations near the transitions to stationary patterns.",
        "positive": "Molecular dynamics simulations of the properties of water-methanol\n  mixtures. Effects of force fields: Isothermal-isobaric molecular dynamics simulations are used to examine the\nmicroscopic structure and some properties of water-methanol liquid mixture. The\nTIP4P/2005 and SPC/E water models are combined with the united atom TraPPE and\nthe all-atom force field model for methanol. Our principal focus is to evaluate\nthe quality of predictions of different combinations of model force fields\nconcerning the composition dependence of basic properties of this system.\nSpecifically, we explored the composition effects on density, excess molar\nvolume and excess entropy, as well as on the surface tension and static\ndielectric constant. In addition, the structural properties are described in\nterms of the coordination numbers and the average number of hydrogen bonds\nbetween molecules of constituent species. Finally, the composition dependence\nof self-diffusion coefficients of the species is evaluated. All theoretical\npredictions are tested with respect to experimental data."
    },
    {
        "anchor": "Effect of optical purity on phase sequence in antiferroelectric liquid\n  crystals: We use the discrete phenomenological model to study theoretically the phase\ndiagrams in antiferroelectric liquid crystals (AFLCs) as a function of optical\npurity and temperature. Recent experiments have shown that in some systems the\nnumber of phases is reduced if the optical purity is extremely high. In some\nmaterials the SmC$_{A}^{\\star}$ phase is the only stable tilted smectic phase\nin the pure sample. In the scope of the presented model this high sensitivity\nof the phase sequence in the AFLCs to optical purity is attributed to the\npiezoelectric coupling which is reduced if optical purity is reduced. We limit\nour study to three topologically equal phases - SmC$^{*}$, SmC$_{\\alpha}^{*}$\nand SmC$_{A}^{*}$ and show that the reduction of optical purity forces the\nsystem from the antiferroelectric to the ferroelectric phase with a possible\nSmC$_{\\alpha}^{\\star}$ between them. The effect of the flexoelectric and\nquadrupolar coupling is considered as well. If the phase diagram includes only\ntwo phases, SmC$^{\\star}$ and SmC$%_{A}^{\\star}$, the flexoelectric coupling is\nvery small. The materials which exhibit the SmC$_{\\alpha}^{\\star}$ in a certain\nrange of optical purity and temperature, can be expected to have a significant\nflexoelectric coupling that is comparable with the piezoelectric coupling. And\nfinally, when temperature is lowered the phase sequence SmA $\\to $\nSmC$%_{\\alpha}^{\\star}$ $\\to $ SmC$^{\\star}$ $\\to $ SmC$%_{A}^{\\star}$ is\npossible only in materials in which quadrupolar coupling is very strong.",
        "positive": "Micro-Capsules in Shear Flow: This paper deals with flow-induced shape transitions of elastic capsules. The\nstate of the art concerning both theory and experiments is briefly reviewed\nstarting with dynamically induced small deformation of initially spherical\ncapsules and the formation of wrinkles on polymerized membranes. Initially\nnon-spherical capsules show tumbling and tank-treading motion in shear flow.\nTheoretical descriptions of the transition between these two types of motion\nassuming a fixed shape are at variance with the full capsule dynamics obtained\nnumerically. To resolve the discrepancy, we expand the exact equations of\nmotion for small deformations and find that shape changes play a dominant role.\nWe classify the dynamical phase transitions and obtain numerical and analytical\nresults for the phase boundaries as a function of viscosity contrast, shear and\nelongational flow rate. We conclude with perspectives on timedependent flow, on\nshear-induced unbinding from surfaces, on the role of thermal fluctuations, and\non applying the concepts of stochastic thermodynamics to these systems."
    },
    {
        "anchor": "Quasiuniversal connectedness percolation of polydisperse rod systems: The connectedness percolation threshold (eta_c) and critical coordination\nnumber (Z_c) of systems of penetrable spherocylinders characterized by a length\npolydispersity are studied by way of Monte Carlo simulations for several aspect\nratio distributions. We find that (i) \\eta_c is a nearly universal function of\nthe weight-averaged aspect ratio, with an approximate inverse dependence that\nextends to aspect ratios that are well below the slender rod limit and (ii)\nthat percolation of impenetrable spherocylinders displays a similar\nquasiuniversal behavior. For systems with a sufficiently high degree of\npolydispersity, we find that Z_c can become smaller than unity, in analogy with\nobservations reported for generalized and complex networks.",
        "positive": "Kremer-Grest models for commodity polymer melts: Linking theory,\n  experiment and simulation at the Kuhn scale: The Kremer-Grest (KG) polymer model is a standard model for studying generic\npolymer properties in Molecular Dynamics simulations. It owes its popularity to\nits simplicity and computational efficiency, rather than its ability to\nrepresent specific polymers species and conditions. Here we show, that by\ntuning the chain stiffness it is possible to adapt the KG model to model melts\nof real polymers. In particular, we provide mapping relations from KG to SI\nunits for a wide range of commodity polymers. The connection between the\nexperimental and the KG melts is made at the Kuhn scale, i.e. at the crossover\nfrom chemistry-specific small scale to the universal large scale behavior. We\nexpect Kuhn scale-mapped KG models to faithfully represent universal properties\ndominated by the large scale conformational statistics and dynamics of flexible\npolymers. In particular, we observe very good agreement between entanglement\nmoduli of our KG models and the experimental moduli of the target polymers."
    },
    {
        "anchor": "Self-Templating Assembly of Soft Microparticles into Complex\n  Tessellations: Self-assembled monolayers of microparticles encoding Archimedean and\nnon-regular tessellations promise unprecedented structure-property\nrelationships for a wide spectrum of applications in fields ranging from\noptoelectronics to surface technology. Yet, despite numerous computational\nstudies predicting the emergence of exotic structures from simple interparticle\ninteractions, the experimental realization of non-hexagonal patterns remains\nchallenging. Not only kinetic limitations often hinder structural relaxation,\nbut also programming the inteparticle interactions during assembly, and hence\nthe target structure, remains an elusive task. Here, we demonstrate how a\nsingle type of soft polymeric microparticle (microgels) can be assembled into a\nwide array of complex structures as a result of simple pairwise interactions.\nWe first let microgels self-assemble at a water-oil interface into a\nhexagonally packed monolayer, which we then compress to varying degrees and\ndeposit onto a solid substrate. By repeating this process twice, we find that\nthe resultant structure is not the mere stacking of two hexagonal patterns. The\nfirst monolayer retains its hexagonal structure and acts as a template into\nwhich the particles of the second monolayer rearrange to occupy interstitial\npositions. The frustration between the two lattices generates new symmetries.\nBy simply varying the packing fraction of the two monolayers, we obtain not\nonly low-coordination structures such as rectangular and honeycomb lattices,\nbut also rhomboidal, hexagonal, and herringbone superlattices which display\nnon-regular tessellations. Molecular dynamics simulations show that these\nstructures are thermodynamically stable and develop from short-ranged repulsive\ninteractions, making them easy to predict, and thus opening new avenues to the\nrational design of complex patterns.",
        "positive": "Simultaneous depletion and adsorption in polymer solutions near a solid\n  wall: Polymer solutions exhibit peculiar properties near surfaces: polymer chains\neither adsorb onto or can be repelled by the wall. Only a few techniques are\nable to probe their structure in the vicinity of solid substrates, because of\nthe small length scales over which liquids are influenced by the wall. In this\npaper, we use neutron reflectivity measurements at the interface between a\npolystyrene semidilute solution in a good solvent and a smooth sapphire\nsurface. We show that polymer chains are globally depleted from the solid\nsurface, but contrary to what is generally assumed, this does not prevent some\nchains to still adsorb on the wall. We also observe that the Newtonian flow of\nthe solution has a negligible effect on the size of the depletion layer, which\nis a hypothesis often made but rarely measured in the literature."
    },
    {
        "anchor": "Glassy dynamics: mean-field `landscape' pictures versus growing length\n  scale scenarii: This is a short review on the compatibility between (a) mean-field,\nmode-coupling theories of the glass transition, where potential energy\nlandscape ideas are natural, and (b) the necessity of describing the slowing\ndown of glassy materials in terms of a growing cooperative length, absent from\nmean-field descriptions. We summarize some of the outstanding questions that\nremain before we can say we understand why glasses do not flow.",
        "positive": "Using NMR to Validate First-Principles Granular Flow Equations: Nuclear magnetic resonance (NMR) experiments are described for two\ngranular-flow systems, the vibrofluidized bed and the gas-fluidized bed. Using\npulsed field gradient, magnetic resonance imaging, and hyperpolarized gas NMR,\ndetailed information is obtained for the density and motions of both grains and\ninterstitial gas. For the vibrofluidized bed, the granular temperature profile\nis measured and compared with a first-principles formulation of granular\nhydrodynamics. For the gas-fluidized bed, dynamic correlations in the grain\ndensity are used to measure the bubble velocity and hyperpolarized xenon gas\nNMR is used to measure the bubble-emulsion exchange rate. A goal of these\nmeasurements is to verify in earth gravity first-principles theories of\ngranular flows, which then can be used to make concrete predictions for\ngranular flows in reduced gravity."
    },
    {
        "anchor": "Swarm Hunting and Clusters Turning Inside Out in Chemically\n  Communicating Active Mixtures: A large variety of microorganisms produce molecules to communicate via\ncomplex signaling mechanisms such as quorum sensing and chemotaxis. The\nbiological diversity is enormous, but synthetic inanimate colloidal\nmicroswimmers mimic microbiological communication (synthetic chemotaxis) and\nmay be used to explore collective behaviour beyond the one-species limit in\nsimpler setups. In this work we combine particle based and continuum\nsimulations as well as linear stability analyses, and study a physical minimal\nmodel of two chemotactic species. We observed a rich phase diagram comprising a\n\"hunting swarm phase\", where both species self-segregate and form swarms,\npursuing, or hunting each other, and a \"core-shell-cluster phase\", where one\nspecies forms a dense cluster, which is surrounded by a (fluctuating) corona of\nparticles from the other species. Once formed, these clusters can dynamically\nturn inside out, representing a \"species-reversal\". These results exemplify a\nphysical route to collective behaviours in microorganisms and active colloids,\nwhich are so-far known to occur only for comparatively large and complex\nanimals like insects or crustaceans.",
        "positive": "Mode instabilities and dynamic patterns in a colony of self-propelled\n  surfactant particles covering a thin liquid layer: We consider a colony of point-like self-propelled surfactant particles\n(swimmers) without direct interactions that cover a thin liquid layer on a\nsolid support. Although the particles predominantly swim normal to the free\nfilm surface, their motion also has a component parallel to the film surface.\nThe coupled dynamics of the swimmer density and film height profile is captured\nin a long-wave model allowing for diffusive and convective transport of the\nswimmers (including rotational diffusion). The dynamics of the film height\nprofile is determined by three physical effects: the upward pushing force of\nthe swimmers onto the liquid-gas interface that always destabilizes the flat\nfilm, the solutal Marangoni force due to gradients in the swimmer concentration\nthat always acts stabilising, and finally the rotational diffusion of the\nswimmers together with the in-plance active motion that acts either stabilising\nor destabilising. After reviewing and extending the analysis of the linear\nstability of the flat film with uniform swimmer density, we analyse the full\nnonlinear dynamic equations and show that point-like swimmers, which only\ninteract via long-wave deformations of the liquid film, self-organise in highly\nregular (standing, travelling and modulated waves) and various irregular\npatterns for swimmer density and film height."
    },
    {
        "anchor": "Emergence of hexatic and long-range herringbone order in two-dimensional\n  smectic liquid crystals : A Monte Carlo study: Using a high resolution Monte Carlo simulation technique based on\nmulti-histogram method and cluster-algorithm, we have investigated critical\nproperties of a coupled XY model, consists of a six-fold symmetric hexatic and\na three-fold symmetric herringbone field, in two dimensions. The simulation\nresults demonstrate a series of novel continues transitions, in which both\nlong-range hexatic and herringbone orderings are established simultaneously. It\nis found that the specific-heat anomaly exponents for some regions in coupling\nconstants space are in excellent agreement with the experimentally measured\nexponents extracted from heat-capacity data near the smecticA-hexaticB\ntransition of two-layer free standing films",
        "positive": "Comment on the paper: Quantum backaction of optical observations on\n  Bose-Einstein condensates by U. Leonhardt, T. Kiss, and P. Piwnicki, Eur.\n  Phys. J. D7, 413 (1999): A recent paper, Quantum backaction of optical observations on Bose-Einstein\ncondensates by U. Leonhardt, T. Kiss, and P. Piwnicki, Eur. Phys. J. D7, 413\n(1999), emphasized that the limit of dispersive imaging of Bose-Einstein\ncondensates with off-resonant light is not residual absorption, but a different\nform of quantum backaction of the probe light. This note points out that these\nconclusions are incorrect, and that Rayleigh scattering is the dominant quantum\nbackaction of dispersive imaging."
    },
    {
        "anchor": "Coupled Bose-Einstein condensate: Collapse for attractive interaction: We study the collapse in a coupled Bose-Einstein condensate of two types of\nbosons 1 and 2 under the action of a trap using the time-dependent\nGross-Pitaevskii equation. The system may undergo collapse when one, two or\nthree of the scattering lengths $a_{ij}$ for scattering of boson $i$ with $j$,\n$i,j = 1, 2 $, are negative representing an attractive interaction. Depending\non the parameters of the problem a single or both components of the condensate\nmay experience collapse.",
        "positive": "Buckling without bending morphogenesis: Nonlinearities, spatial\n  confinement, and branching hierarchies: During morphogenesis, a featureless convex cerebellum develops folds. As it\ndoes so, the cortex thickness is thinnest at the crest (gyri) and thickest at\nthe trough (sulci) of the folds. This observation cannot be simply explained by\nelastic theories of buckling. A recent minimal model explained this phenomenon\nby modeling the developing cortex as a growing fluid under the constraints of\nradially spanning elastic fibers, a plia membrane and a nongrowing sub-cortex\n(Engstrom, et. al., PRX 2019). In this minimal buckling without bending\nmorphogenesis (BWBM) model, the elastic fibers were assumed to act linearly\nwith strain. Here, we explore how nonlinear elasticity influences shape\ndevelopment within BWBM. The nonlinear elasticity generates a quadratic\nnonlinearity in the differential equation governing the system's shape and\nleads to sharper troughs and wider crests, which is an identifying\ncharacteristic of cerebellar folds at later stages in development. As\ndeveloping organs are typically not in isolation, we also explore the effects\nof steric confinement, and observe flattening of the crests. Finally, as a\nparadigmatic example, we propose a hierarchical version of BWBM from which a\nnovel mechanism of branching morphogenesis naturally emerges to qualitatively\npredict later stages of the morphology of the developing cerebellum."
    },
    {
        "anchor": "Stress and large-scale spatial structures in dense, driven granular\n  flows: We study the appearance of large-scale dynamical heterogeneities in a\nsimplified model of a driven, dissipative granular system. Simulations of\nsteady-state gravity-driven flows of inelastically colliding hard disks show\nthe formation of large-scale linear structures of particles with a high\ncollision frequency. These chains can be shown to carry much of the collisional\nstress in the system due to a dynamical correlation that develops between the\nmomentum transfer and time between collisions in these \"frequently-colliding\"\nparticles. The lifetime of these dynamical stress heterogeneities is seen to\ngrow as the flow velocity decreases towards jamming, leading to slowly decaying\nstress correlations reminiscent of the slow dynamics observed in supercooled\nliquids.",
        "positive": "Polymorphic self-assembly of helical tubules is kinetically controlled: In contrast to most self-assembling synthetic materials, which undergo\nunbounded growth, many biological self-assembly processes are self-limited.\nThat is, the assembled structures have one or more finite dimensions that are\nmuch larger than the size scale of the individual monomers. In many such cases,\nthe finite dimension is selected by a preferred curvature of the monomers,\nwhich leads to self-closure of the assembly. In this article, we study an\nexample class of self-closing assemblies: cylindrical tubules that assemble\nfrom triangular monomers. By combining kinetic Monte Carlo simulations, free\nenergy calculations, and simple theoretical models, we show that a range of\nprogrammable size scales can be targeted by controlling the intricate balance\nbetween the preferred curvature of the monomers and their interaction\nstrengths. However, their assembly is kinetically controlled - the tubule\nmorphology is essentially fixed shortly after closure, resulting in a\ndistribution of tubule widths that is significantly broader than the\nequilibrium distribution. We develop a simple kinetic model based on this\nobservation and the underlying free-energy landscape of assembling tubules that\nquantitatively describes the distributions. Our results are consistent with\nrecent experimental observations of tubule assembly from triangular DNA origami\nmonomers. The modeling framework elucidates design principles for assembling\nself-limited structures from synthetic components, such as artificial\nmicrotubules that have a desired width and chirality."
    },
    {
        "anchor": "Topological colloids: Abundant in nature, colloids also find increasingly important applications in\nscience and technology, ranging from direct probing of kinetics in crystals and\nglasses to fabrication of third-generation quantum-dot solar cells. Because\nnaturally occurring colloids have a shape that is typically determined by\nminimization of interfacial tension (for example, during phase separation) or\nfaceted crystal growth, their surfaces tend to have minimum-area spherical or\ntopologically equivalent shapes such as prisms and irregular grains (all\ncontinuously deformable - homeomorphic - to spheres). Although toroidal DNA\ncondensates and vesicles with different numbers of handles can exist and soft\nmatter defects can be shaped as rings and knots, the role of particle topology\nin colloidal systems remains unexplored. Here we fabricate and study colloidal\nparticles with different numbers of handles and genus g ranging from 1 to 5.\nWhen introduced into a nematic liquid crystal - a fluid made of rod-like\nmolecules that spontaneously align along the so-called \"director\" - these\nparticles induce three-dimensional director fields and topological defects\ndictated by colloidal topology. Whereas electric fields, photothermal melting\nand laser tweezing cause transformations between configurations of\nparticle-induced structures, three-dimensional nonlinear optical imaging\nreveals that topological charge is conserved and that the total charge of\nparticle-induced defects always obeys predictions of the Gauss-Bonnet and\nPoincare-Hopf index theorems. This allows us to establish and experimentally\ntest the procedure for assignment and summation of topological charges in\nthree-dimensional director fields. Our findings lay the groundwork for new\napplications of colloids and liquid crystals that range from topological memory\ndevices, through new types of self-assembly, to the experimental study of\nlow-dimensional topology.",
        "positive": "Transport coefficients for an inelastic gas around uniform shear flow:\n  Linear stability analysis: The inelastic Boltzmann equation for a granular gas is applied to spatially\ninhomogeneous states close to the uniform shear flow. A normal solution is\nobtained via a Chapman-Enskog-like expansion around a local shear flow\ndistribution. The heat and momentum fluxes are determined to first order in the\ndeviations of the hydrodynamic field gradients from their values in the\nreference state. The corresponding transport coefficients are determined from a\nset of coupled linear integral equations which are approximately solved by\nusing a kinetic model of the Boltzmann equation. The main new ingredient in\nthis expansion is that the reference state $f^{(0)}$ (zeroth-order\napproximation) retains all the hydrodynamic orders in the shear rate. In\naddition, since the collisional cooling cannot be compensated locally for\nviscous heating, the distribution $f^{(0)}$ depends on time through its\ndependence on temperature. This means that in general, for a given degree of\ninelasticity, the complete nonlinear dependence of the transport coefficients\non the shear rate requires the analysis of the {\\em unsteady} hydrodynamic\nbehavior. To simplify the analysis, the steady state conditions have been\nconsidered here in order to perform a linear stability analysis of the\nhydrodynamic equations with respect to the uniform shear flow state. Conditions\nfor instabilities at long wavelengths are identified and discussed."
    },
    {
        "anchor": "Conversion of a force curve between chemically the same surfaces into\n  the number density distribution of the particles on the surface using a\n  structure factor: Line optical tweezer and colloidal-probe atomic force microscopy can measure\nforce curves between two large colloidal particles of chemically the same\nsurfaces in a suspension of small colloidal particles. Recently, the authors\nproposed a transform theory to obtain the number density distribution of the\nsmall colloidal particles on the large colloidal particle from the force curve.\nIn this short letter, we propose another method which utilizes Ornstein-Zernike\nequation coupled with a closure equation instead of Kirkwood superposition\napproximation. The new transform theory uses a structure factor measured by\nx-ray or neutron scattering, and applies Nelder-Mead method to find the\nsolution. Since it is known that Ornstein-Zernike equation coupled with the\nclosure equation is accurate compared with Kirkwood superposition\napproximation, the new transform theory is theoretically better than the\nprevious methods when the structure factor and the closure equation are\nreliable.",
        "positive": "Origin of crack pattern in the deposition from drying colloidal\n  suspension: The fracture mechanics was widely employed to explain the crack propagation\nin the deposition produced by drying colloidal suspension. However, more\ncomplex than conventional fracture, those cracks periodically distribute and\nmake up a unique pattern. This still remains mysterious so far. Inspired by the\nconcept of spinodal decomposition, here, we develop the theory to elucidate the\nspatial arrangement of the cracks, which indicates that the crack pattern is\ngenerated by the phase separation of colloidal clusters and water. It concludes\nthat the crack spacing results from the wavelength of the concentration\nfluctuation during the phase separation, linearly growing with the increase of\nthe deposition thickness and initial particle concentration, which is\nconsistent with experimental results."
    },
    {
        "anchor": "Configurational and Vibrational Entropy in Hydrogen-bonded Fluids: The thermodynamics of liquids and supercritical fluids is notorious for\neluding a general theory, as can be done for crystalline solids on the basis of\nphonons and crystal symmetry. The extension of solid state notions such as\nconfigurational entropy and phonons to the liquid state remains an intriguing\nbut challenging topic. This is particularly true for liquids like water whose\nmany structural anomalies give it unique properties. Here, for simple fluids,\nwe specify the thermodynamics across the liquid, supercritical, and gaseous\nstates using the spectrum of propagating phonons, thereby determining the\nnon-ideal entropy of the fluid using a single parameter arising from this\nphonon spectrum. This identifies a marked distinction between these \"simple\"\nfluids, and hydrogen bonded fluids whose non-ideal entropy cannot be determined\nby the phonon spectrum alone. We relate this phonon theory of thermodynamics to\nthe previously observed excess entropy scaling in liquids and how the phonon\nspectrum creates corresponding states across the fluid phase diagram. These\nresults provide important theoretical understanding to supercritical fluid,\nwhose properties are still poorly understood despite widespread deployment in\nenvironmental and energy applications.",
        "positive": "Minimal continuum theories of structure formation in dense active fluids: Self-sustained dynamical phases of living matter can exhibit remarkable\nsimilarities over a wide range of scales, from mesoscopic vortex structures in\nmicrobial suspensions and motility assays of biopolymers to turbulent\nlarge-scale instabilities in flocks of birds or schools of fish. Here, we argue\nthat, in many cases, the phenomenology of such active states can be efficiently\ndescribed in terms of fourth- and higher-order partial differential equations.\nStructural transitions in these models can be interpreted as Landau-type\nkinematic transitions in Fourier (wavenumber) space, suggesting that\nmicroscopically different biological systems can share universal\nlong-wavelength features. This general idea is illustrated through numerical\nsimulations for two classes of continuum models for incompressible active\nfluids: a Swift-Hohenberg-type scalar field theory, and a minimal vector model\nthat extends the classical Toner-Tu theory and appears to be a promising\ncandidate for the quantitive description of dense bacterial suspensions. We\nalso discuss briefly how microscopic symmetry-breaking mechanisms can enter\nmacroscopic continuum descriptions of collective microbial motion near surfaces\nand conclude by outlining future applications."
    },
    {
        "anchor": "Nudged Elastic Band calculation of the binding potential for liquids at\n  interfaces: The wetting behavior of a liquid on solid substrates is governed by the\nnature of the effective interaction between the liquid-gas and the solid-liquid\ninterfaces, which is described by the binding or wetting potential $g(h)$ which\nis an excess free energy per unit area that depends on the liquid film height\n$h$. Given a microscopic theory for the liquid, to determine $g(h)$ one must\ncalculate the free energy for liquid films of any given value of $h$; i.e. one\nneeds to create and analyze out-of-equilibrium states, since at equilibrium\nthere is a unique value of $h$, specified by the temperature and chemical\npotential of the surrounding gas. Here we introduce a Nudged Elastic Band (NEB)\napproach to calculate $g(h)$ and illustrate the method by applying it in\nconjunction with a microscopic lattice density functional theory for the\nliquid. We show too that the NEB results are identical to those obtained with\nan established method based on using a fictitious additional potential to\nstabilize the non-equilibrium states. The advantages of the NEB approach are\ndiscussed.",
        "positive": "Mapping the glassy dynamics of soft spheres onto hard-sphere behavior: We show that the dynamics of soft-sphere systems with purely repulsive\ninteractions can be described by introducing an effective hard-sphere diameter\ndetermined using the Andersen-Weeks-Chandler approximation. We find that this\napproximation, known to describe static properties of liquids, also gives a\ngood description of a dynamical quantity, the relaxation time, even in the\nvicinity of the glass transition."
    },
    {
        "anchor": "Kinetic limitations of cooperativity based drug delivery systems: We study theoretically a novel drug delivery system that utilizes the\noverexpression of certain proteins in cancerous cells for cell specific\nchemotherapy. The system consists of dendrimers conjugated with \"keys\" (ex:\nfolic acid) which \"key-lock\" bind to particular cell membrane proteins (ex:\nfolate receptor). The increased concentration of \"locks\" on the surface leads\nto a longer residence time for the dendrimer and greater incorporation into the\ncell. Cooperative binding of the nanocomplexes leads to an enhancement of cell\nspecificity. However, both our theory and detailed analysis of in-vitro\nexperiments indicate that the degree of cooperativity is kinetically limited.\nWe demonstrate that cooperativity and hence the specificity to particular cell\ntype can be increased by making the strength of individual bonds weaker, and\nsuggest a particular implementation of this idea. The implications of the work\nfor optimizing the design of drug delivery vehicles are discussed.",
        "positive": "Rheological aging and rejuvenation in solid friction contacts: We study the low-velocity (0.1--100 $\\mu$m.s$^{-1}$) frictional properties of\ninterfaces between a rough glassy polymers and smooth silanized glass, a\nconfiguration which gives direct access to the rheology of the adhesive joints\nin which shear localizes. We show that these joints exhibit the full\nphenomenology expected for confined quasi 2D soft glasses: they strengthen\nlogarithmically when aging at rest, and weaken (rejuvenate) when sliding.\nRejuvenation is found to saturate at large velocities. Moreover, aging at rest\nis shown to be strongly accelerated when waiting under finite stress below the\nstatic threshold."
    },
    {
        "anchor": "Dynamics of an asymmetric bilayer lipid membrane in a viscous solvent: Bilayer lipid membranes (BLMs) are an essential component of many biological\nsystems, forming a functional barrier between the cell and the surrounding\nenvironment. When the membrane relaxes from a structural perturbation, the\ndynamics of the relaxation depends on the bilayer structure. We present a model\nof a BLM in a viscous solvent, including an explicit description of a 'thick'\nmembrane, where the fluctuations in the thickness of a monolayer leaflet are\ncoupled to changes in the lipid density within that monolayer. We find\ndispersion relations describing three intuitive forms of bilayer motion,\nincluding a mode describing motion of the intermonolayer surface not noted\npreviously in the literature. Two intrinsic length scales emerge that help\ncharacterise the dynamics; the well known Saffman-Delbruck length and another,\n$\\ell_r$, resulting from the intermonolayer friction. The framework also allows\nfor asymmetry in the BLM parameters between the monolayer leaflets, which is\nfound to couple dynamic modes of bilayer motion.",
        "positive": "New Insights into the Dynamics of Swarming Bacteria: A Theoretical Study: In the present work we simulate the basic two-dimensional dynamics of\nswarming E. coli bacteria on the surface of a moderately soft agar plate.\nIndividual bacteria are modelled by self-propelled ridged bodies (agents),\nwhich interact with each other only through inelastic collision and with the\nhighly viscous environment through damping forces. The motion of single agents\nis modelled closely corresponding to the behaviour of swimming bacteria. The\ndynamics of the model were adjusted to reproduce the experimental measurements\nof swimming E. coli K 12. Accordingly, simulations with loosely packed agents\n(p=0) show typical run-and-tumble statistics. In contrast, simulations with\ndensely packed agents (p=0.3-0.7) are dominated by interactions (collisions)\nbetween agents which lead to the emergence of swarming behaviour. In addition,\nwe model the motion of single agents on the base of modified run-and-tumble\ndynamics, where the bacteria do not turn actively during the tumble. We show\nthat simulations with densely packed modified agents lead as well the emergence\nof swarming behaviour, if rotational diffusion is considered."
    },
    {
        "anchor": "Anchoring-driven spontaneous rotations in active gel droplets: We study the dynamics of an active gel droplet with imposed orientational\nanchoring (normal or planar) at its surface. We find that if the activity is\nlarge enough droplets subject to strong anchoring spontaneously start to\nrotate, with the sense of rotation randomly selected by fluctuations.\nContractile droplets rotate only for planar anchoring and extensile ones only\nfor normal anchoring. This is because such a combination leads to a pair of\nstable elastic deformations which creates an active torque to power the\nrotation. Interestingly, under these conditions there is a conflict between the\nanchoring promoted thermodynamically and that favoured by activity. By tuning\nactivity and anchoring strength, we find a wealth of qualitatively different\ndroplet morphologies and spatiotemporal patterns, encompassing steady\nrotations, oscillations, and more irregular trajectories. The spontaneous\nrotations we observe are fundamentally different from previously reported\ninstances of rotating defects in active fluids as they require the presence of\nstrong enough anchoring and entail significant droplet shape deformations.",
        "positive": "Molecular-shape- and size-independent power-law dependence of\n  percolation thresholds on radius of gyration in ideal molecular systems: Three-dimensional single-component ideal gas systems composed of model\nhomogeneous rigid molecules in various molecular shapes and sizes are simulated\nby a molecular Monte Carlo simulation technique. We reveal that percolation\nthresholds of such single-component systems result in, when the molecular\nvolume is fixed, power-law decreasing functions of the radius of gyration\n(gyradius) of the molecules. The systems with the same parameter set of the\nmolecular volume and radius of gyration, but in different molecular shapes,\nshow the identical value of the percolation threshold. Moreover, we also reveal\nthat a dimensionless scale-free parameter, which is the ratio between the\nradius of gyration and real cube root of the molecular volume, uniquely\ndetermines the percolation threshold."
    },
    {
        "anchor": "Influence of solvent quality on polymer solutions: a Monte Carlo study\n  of bulk and interfacial properties: The effect of solvent quality on dilute and semi-dilute regimes of polymers\nin solution is studied by means of Monte Carlo simulations. The equation of\nstate, adsorptions near a hard wall, wall-polymer surface tension and effective\ndepletion potentials are all calculated as a function of concentration and\nsolvent quality. We find important differences between polymers in good and\ntheta solvents. In the dilute regime, the physical properties for polymers in a\ntheta solvent closely resemble those of ideal polymers. In the semi-dilute\nregime, however, significant differences are found.",
        "positive": "Motility and pair-wise interactions of chemically active droplets in 1-D\n  confinement: Self-propelled droplets serve as ideal model systems to delve deeper into\nunderstanding of the motion of biological micro-swimmers by simulating their\nmotility. Biological microorganisms are renowned for showcasing a diverse array\nof dynamic swimming behaviors when confronted with physical constraints. This\nstudy aims to elucidate the impact of physical constraints on swimming\ncharacteristics of biological microorganisms. To achieve this, we present\nobservations on the individual and pair-wise behavior of micellar solubilized\nself-propelled 4-Cyano-4'-pentyl-biphenyl (5CB) oil droplets in a square\ncapillary channel filled with a surfactant trimethyl ammonium bromide (TTAB)\naqueous solution. To explore the effect of the underlying P\\'eclet ($Pe$)\nnumber of the swimming droplets, the study is also performed in the presence of\nadditives such as high molecular weight polymer Polyethylene oxide (PEO) and\nmolecular solute glycerol. The capillary confinement restricts droplet to\npredominantly one-dimensional (1D) motion, albeit with noticeable differences\nin their motion across the three scenarios. Through a characterization of the\nchemical and hydrodynamic flow fields surrounding the droplets, we illustrate\nthat the modification of the droplets' chemical field due to confinement varies\nsignificantly based on the underlying differences in the P\\'eclet number ($Pe$)\nin these cases. This alteration in the chemical field distribution notably\naffects the individual droplets' motion. Moreover, these distinct chemical\nfield interactions between the droplets also lead to variations in their\npair-wise motion, ranging from behaviors like chasing to scattering."
    },
    {
        "anchor": "Rotating spherical particle in a continuous viscoelastic medium -- a\n  microrheological example situation: Using analytical calculations, we characterize the rotational behavior of a\nrigid spherical particle when subject to a net external torque in a continuous\nviscoelastic environment. On long time scales, the embedding medium can either\nfeature a net terminal flow, like a fluid, or damped reversible dynamics, like\nan elastic solid. The coupling of the sphere to its environment together with\nthe therein induced deformations and flows are taken into account explicitly.\nIn reality, using magnetically anisotropic particles, the torque can, for\ninstance, be applied via magnetic fields. We calculate corresponding response\nfunctions. This connects our study to evaluations of microrheological\ninvestigations.",
        "positive": "Specificity and stability in topology of protein networks: Molecular networks guide the biochemistry of a living cell on multiple\nlevels: its metabolic and signalling pathways are shaped by the network of\ninteracting proteins, whose production, in turn, is controlled by the genetic\nregulatory network. To address topological properties of these two networks we\nquantify correlations between connectivities of interacting nodes and compare\nthem to a null model of a network, in which al links were randomly rewired. We\nfind that for both interaction and regulatory networks, links between highly\nconnected proteins are systematically suppressed, while those between a\nhighly-connected and low-connected pairs of proteins are favored. This effect\ndecreases the likelihood of cross talk between different functional modules of\nthe cell, and increases the overall robustness of a network by localizing\neffects of deleterious perturbations."
    },
    {
        "anchor": "Direct numerical simulations of the modified Poisson-Nernst-Planck\n  equations for the charging dynamics of cylindrical electrolyte-filled pores: Understanding how electrolyte-filled porous electrodes respond to an applied\npotential is important to many electrochemical technologies. Here, we consider\na model supercapacitor of two blocking cylindrical pores on either side of a\ncylindrical electrolyte reservoir. A stepwise potential difference $2\\Phi$\nbetween the pores drives ionic fluxes in the setup, which we study through the\nmodified Poisson-Nernst-Planck equations, solved with finite elements. We focus\nour discussion on the dominant timescales with which the pores charge and how\nthese timescales depend on three dimensionless numbers. Next to the\ndimensionless applied potential $\\Phi$, we consider the ratio $R/R_b$ of the\npore's resistance $R$ to the bulk reservoir resistance $R_b$ and the ratio\n$r_{p}/\\lambda$ of the pore radius $r_p$ to the Debye length $\\lambda$. We\ncompare our data to theoretical predictions by Aslyamov and Janssen ($\\Phi$),\nPosey and Morozumi ($R/R_b$), and Henrique, Zuk, and Gupta ($r_{p}/\\lambda$).\nThrough our numerical approach, we delineate the validity of these theories and\nthe assumptions on which they were based.",
        "positive": "Polymer Informatics: Current Status and Critical Next Steps: Artificial intelligence (AI) based approaches are beginning to impact several\ndomains of human life, science and technology. Polymer informatics is one such\ndomain where AI and machine learning (ML) tools are being used in the efficient\ndevelopment, design and discovery of polymers. Surrogate models are trained on\navailable polymer data for instant property prediction, allowing screening of\npromising polymer candidates with specific target property requirements.\nQuestions regarding synthesizability, and potential (retro)synthesis steps to\ncreate a target polymer, are being explored using statistical means.\nData-driven strategies to tackle unique challenges resulting from the\nextraordinary chemical and physical diversity of polymers at small and large\nscales are being explored. Other major hurdles for polymer informatics are the\nlack of widespread availability of curated and organized data, and approaches\nto create machine-readable representations that capture not just the structure\nof complex polymeric situations but also synthesis and processing conditions.\nMethods to solve inverse problems, wherein polymer recommendations are made\nusing advanced AI algorithms that meet application targets, are being\ninvestigated. As various parts of the burgeoning polymer informatics ecosystem\nmature and become integrated, efficiency improvements, accelerated discoveries\nand increased productivity can result. Here, we review emergent components of\nthis polymer informatics ecosystem and discuss imminent challenges and\nopportunities."
    },
    {
        "anchor": "Shape dynamics of a red blood cell in Poiseuille flow: We use numerical simulations to study the dynamics of red blood cells (RBCs)\nin unconfined and confined Poiseuille flow. Previous numerical studies with 3D\nvesicles have indicated that the slipper shape observed in experiments at high\ncapillary number can be attributed to the bistability due to the interplay of\nwall push and outward migration tendency at higher viscosity contrasts. In this\npaper, we study this outward migration and bistability using numerical\nsimulations for 3D capsules and provide phase diagrams of RBC dynamics with and\nwithout viscosity contrast. We observe a bistability of slipper and croissants\nin confined Poiseuille flow with viscosity contrast as observed in experiments.",
        "positive": "Active nematics are intrinsically phase-separated: Two-dimensional nonequilibrium nematic steady states, as found in agitated\ngranular-rod monolayers or films of orientable amoeboid cells, were predicted\n[Europhys. Lett. {\\bf 62} (2003) 196] to have giant number fluctuations, with\nstandard deviation proportional to the mean. We show numerically that the\nsteady state of such systems is {\\em macroscopically phase-separated}, yet\ndominated by fluctuations, as in the Das-Barma model [PRL {\\bf 85} (2000)\n1602]. We suggest experimental tests of our findings in granular and\nliving-cell systems."
    },
    {
        "anchor": "Shear banding in monodisperse polymer melt: We performed a series of molecular dynamics simulations on monodisperse\npolymer melts to investigate the formation of shear banding. Under high shear\nrates, shear banding occurs, which is accompanied with the entanglement\nheterogeneity intimately. Interestingly, the same linear relationship between\nthe end-to-end distance $R_{ee}$ and entanglement density $Z$ is observed at\nhomogeneous flow before the onset of shear banding and at shear banding state,\nwhere $R_{ee} \\sim [ln(W_i^{0.87})- \\xi_0]Z$ is proposed as the criterion to\ndescribe the dynamic force balance of molecular chain in flow with a high rate.\nWe establish a scaling relation between the disentanglement rate $V_d$ and\nWeissenberg number $W_i$ as $V_d \\sim W_i^{0.87}$ for stable flow in\nhomogeneous shear and shear banding states. Deviating from this relation leads\nto force imbalance and results in the emergence of shear banding. The formation\nof shear banding prevents chain from further stretching and disentanglement.\nThe transition from homogeneous shear to shear banding partially dissipates the\nincreased free energy from shear and reduces the free energy of the system.",
        "positive": "Thermodynamic behavior of binary mixtures of hard spheres:\n  Semianalytical solutions on a Husimi lattice built with cubes: We study binary mixtures of hard particles, which exclude up to their $k$th\nnearest neighbors ($k$NN) on the simple cubic lattice and have activities\n$z_k$. In the first model analyzed, point particles (0NN) are mixed with 1NN\nones. The grand-canonical solution of this model on a Husimi lattice built with\ncubes unveils a phase diagram with a fluid and a solid phase separated by a\ncontinuous and a discontinuous transition line which meet at a tricritical\npoint. A density anomaly, characterized by minima in isobaric curves of the\ntotal density of particles against $z_0$ (or $z_1$), is also observed in this\nsystem. Overall, this scenario is identical to the one previously found for\nthis model when defined on the square lattice. The second model investigated\nconsists of the mixture of 1NN particles with 2NN ones. In this case, a very\nrich phase behavior is found in its Husimi lattice solution, with two solid\nphases - one associated with the ordering of 1NN particles ($S1$) and the other\nwith the ordering of 2NN ones ($S2$) -, beyond the fluid ($F$) phase. While the\ntransitions between $F$-$S2$ and $S1$-$S2$ phases are always discontinuous, the\n$F$-$S1$ transition is continuous (discontinuous) for small (large) $z_2$. The\ncritical and coexistence $F$-$S1$ lines meet at a tricritical point. Moreover,\nthe coexistence $F$-$S1$, $F$-$S2$ and $S1$-$S2$ lines meet at a triple point.\nDensity anomalies are absent in this case."
    },
    {
        "anchor": "Short Time and Structural Dynamics in Polypropylene Glycol Nanocomposite: The dynamics of polypropylene glycol, both neat and attached to silica\nnanoparticles, were investigated using elastic neutron backscattering and\ndielectric spectroscopy. The mean square displacement measured by the former is\nsuppressed by the particles at temperatures corresponding to a dielectric\nsecondary relaxation (that involves only a portion of the repeat unit) and the\nsegmental relaxation (glass transition). Despite the suppression of the\ndisplacements, the motions are faster in the nanocomposite, primarily due to\npoorer packing (lower density) at the particle interface. At very low\ntemperatures we discovered a new dynamic process in the polymer. Reflecting its\nvery local nature, this process is unaffected by attachment of the chains to\nthe silica.",
        "positive": "Novel mesophase behavior in two-dimensional binary solid solutions: Monte Carlo simulations were used to study the assembly of binary mixtures of\nhard disks with squares, where the components have size ratios that optimize\ntheir co-assembly into compositionally disordered solids. It is observed that,\nalong with the enhanced regions of solid miscibility, a continuous-looking\ntransition from the disk-like to the square-like behavior occurred through a\nnovel mosaic (M) phase, which seamlessly bridges the regions of hexatic\nmesophase of disks and the tetratic mesophase of squares. The M phase has\ninterspersed tetratic, hexatic, and rhombic-like locally ordered clusters."
    },
    {
        "anchor": "Simulation of radiation transfer and coherent backscattering in nematic\n  liquid crystals: We consider the multiple scattering of light by fluctuations of the director\nin a nematic liquid crystal. Using methods of numerical simulation the peak of\nthe coherent backscattering and the coefficients of anisotropic diffusion are\ncalculated. The calculations were carried out without simplifying assumptions\non the properties of the liquid crystal. The process of multiple scattering was\nsimulated as a random walk of photons in the medium. We investigated in detail\nthe transition to the diffusion regime. The dependence of the diffusion\ncoefficients on the applied magnetic field and the wavelength of light were\nstudied. The results of simulation showed a non-monotonic dependence of the\ndiffusion coefficients on the external magnetic field. A qualitative\nexplanation of this behaviour was suggested using a simple scalar model. For\ncalculation of the peak of the coherent backscattering we used the\nsemianalytical approach as long as in nematic liquid crystals this peak is\nextremely narrow. The parameters of backscattering peak and of diffusion\ncoefficients which were found in numerical simulations were compared with the\nexperimental data and the results of analytical calculation.",
        "positive": "Self-Consistent Field study of Polyelectrolyte Brushes: We formulate a self-consistent field theory for polyelectrolyte brushes in\nthe presence of counterions. We numerically solve the self-consistent field\nequations and study the monomer density profile, the distribution of\ncounterions, and the total charge distribution. We study the scaling relations\nfor the brush height and compare them to the prediction of other theories. We\nfind a weak dependence of the brush height on the grafting density.We fit the\ncounterion distribution outside the brush by the Gouy-Chapman solution for a\nvirtual charged wall. We calculate the amount of counterions outside the brush\nand find that it saturates as the charge of the polyelectrolytes increases."
    },
    {
        "anchor": "Coexisting Ordered States, Local Equilibrium-like Domains, and Broken\n  Ergodicity in a Non-turbulent Rayleigh-B\u00e9nard Convection at Steady-state: A challenge in fundamental physics and especially in thermodynamics is to\nunderstand emergent order in far-from-equilibrium systems. While at\nequilibrium, temperature plays the role of a key thermodynamic variable whose\nuniformity in space and time defines the equilibrium state the system is in,\nthis is not the case in a far-from-equilibrium driven system. When energy flows\nthrough a finite system at steady-state, temperature takes on a\ntime-independent but spatially varying character. In this study, the convection\npatterns of a Rayleigh-B{\\'e}nard fluid cell at steady-state is used as a\nprototype system where the temperature profile and fluctuations are measured\nspatio-temporally. The thermal data is obtained by performing high-resolution\nreal-time infrared calorimetry on the convection system as it is first driven\nout-of-equilibrium when the power is applied, achieves steady-state, and then\nas it gradually relaxes back to room temperature equilibrium when the power is\nremoved. Our study provides new experimental data on the non-trivial nature of\nthermal fluctuations when stable complex convective structures emerge. The\nthermal analysis of these convective cells at steady-state further yield local\nequilibrium-like statistics. In conclusion, these results correlate the spatial\nordering of the convective cells with the evolution of the system's temperature\nmanifold.",
        "positive": "Onsager theory of length-bidisperse hard rods: Evidence for a\n  nematic-nematic critical point: This manuscript has been withdrawn because of significant overlap with an\nexisting paper (Szabolcs Varga and Istvan Szalai, \"Phase diagrams of binary\nmixtures of hard rods in an external orientational field\", Phys. Chem. Chem.\nPhys., 2:1955-1959, 2000) of which we were, unfortunately, unaware when\nsubmitting our manuscript."
    },
    {
        "anchor": "Grain splitting is a mechanism for grain coarsening in colloidal\n  polycrystals: In established theories of grain coarsening, grains disappear either by\nshrinking or by rotating as a rigid object to coalesce with an adjacent grain.\nHere we report a third mechanism for grain coarsening, in which a grain splits\napart into two regions that rotate in opposite directions to match two adjacent\ngrains' orientations. We experimentally observe both conventional grain\nrotation and grain splitting in 2D colloidal polycrystals. We find that grain\nsplitting occurs via independently rotating \"granules\" whose shapes are\ndetermined by the underlying triangular lattices of the two merging crystal\ngrains. These granules are so small that existing continuum theories of grain\nboundary energy are inapplicable, so we introduce a hard sphere model for the\nfree energy of a colloidal polycrystal. We find that during splitting, the\nsystem overcomes a free energy barrier before ultimately reaching a lower free\nenergy when splitting is complete. Using simulated splitting events and a\nsimple scaling prediction, we find that the barrier to grain splitting\ndecreases as grain size decreases. Consequently, grain splitting is likely to\nplay an important role in polycrystals with small grains. This discovery\nsuggests that mesoscale models of grain coarsening may offer better predictions\nin the nanocrystalline regime by including grain splitting.",
        "positive": "Microphase separation in oil-water mixtures containing hydrophilic and\n  hydrophobic ions: We develop a lattice-based Monte Carlo simulation method for charged mixtures\ncapable of treating dielectric heterogeneities. Using this method, we study\noil-water mixtures containing an antagonistic salt, with hydrophilic cations\nand hydrophobic anions. Our simulations reveal several phases with a spatially\nmodulated solvent composition, in which the ions partition between water-rich\nand water-poor regions according to their affinity. In addition to the recently\nobserved lamellar phase, we find tubular, droplet, and even gyroid phases\nreminiscent of those found in block copolymers and surfactant systems.\nInterestingly, these structures stem from ion-mediated interactions, which\nallows for tuning of the phase behavior via the concentrations, the ionic\nproperties, and the temperature."
    },
    {
        "anchor": "Overdamped Lattice Dynamics of Sedimenting Active Cosserat Crystals: Micropolar active matter requires for its kinematic description both\npositional and orientational degrees of freedom. Activity generates dynamic\ncoupling between these kinematic variables that are absent in micropolar\npassive matter, such as the oriented crystals first studied by the Cosserat\nbrothers. Here we study the effect of uniaxial activity on the dynamics of an\ninitially crystalline state of spheroidal colloids sedimenting slowly in a\nviscous fluid remote from confining boundaries. Despite frictional overdamping\nby the fluid, the crystalline lattice admits traveling waves of position and\norientation. At long wavelengths these obey a vector wave equation with Lam\\'e\nconstants determined by the activity. We find that at least one polarization\nmode of these waves is always unstable, leading to the melting of the crystal.\nThese results are elucidated by identifying an odd-dimensional Poisson\nstructure consisting of a Hamiltonian and an associated Casimir invariant,\nwhere linear combinations of position and orientation are identified as\nconjugate variables. Our results suggest that Poisson structures may exist\ngenerally for active particles in slow viscous flow and thereby allow\nequilibrium arguments to be applied in the presence of these dissipative\nsystems.",
        "positive": "Confinement controlled bend instability of three-dimensional active\n  fluids: Spontaneous growth of long-wavelength deformations is a defining feature of\nactive fluids with orientational order. We investigate the effect of biaxial\nrectangular confinement on the instability of initially shear-aligned 3D\nisotropic active fluids composed of extensile microtubule bundles and kinesin\nmolecular motors. Under confinement, such fluids exhibit finite-wavelength\nself-amplifying bend deformations which grow in the plane orthogonal to the\ndirection of the strongest confinement. Both the instability wavelength and the\ngrowth rate increase with weakening confinement. These findings are consistent\nwith a minimal hydrodynamic model, which predicts that the fastest growing\ndeformation is set by a balance of active driving and elastic relaxation.\nExperiments in the highly confined regime confirm that the instability\nwavelength is set by the balance of active and elastic stresses, which are\nindependently controlled by the concentration of motors and non-motile\ncrosslinkers."
    },
    {
        "anchor": "Minkowski Tensors of Anisotropic Spatial Structure: This article describes the theoretical foundation of and explicit algorithms\nfor a novel approach to morphology and anisotropy analysis of complex spatial\nstructure using tensor-valued Minkowski functionals, the so-called Minkowski\ntensors. Minkowski tensors are generalisations of the well-known scalar\nMinkowski functionals and are explicitly sensitive to anisotropic aspects of\nmorphology, relevant for example for elastic moduli or permeability of\nmicrostructured materials. Here we derive explicit linear-time algorithms to\ncompute these tensorial measures for three-dimensional shapes. These apply to\nrepresentations of any object that can be represented by a triangulation of its\nbounding surface; their application is illustrated for the polyhedral Voronoi\ncellular complexes of jammed sphere configurations, and for triangulations of a\nbiopolymer fibre network obtained by confocal microscopy. The article further\nbridges the substantial notational and conceptual gap between the different but\nequivalent approaches to scalar or tensorial Minkowski functionals in\nmathematics and in physics, hence making the mathematical measure theoretic\nmethod more readily accessible for future application in the physical sciences.",
        "positive": "Activity-driven tissue alignment in proliferating spheroids: We extend the continuum theory of active nematic fluids to study cell flows\nand tissue dynamics inside multicellular spheroids, spherical, self-assembled\naggregates of cells that are widely used as model systems to study tumour\ndynamics. Cells near the surface of spheroids have better access to nutrients\nand therefore proliferate more rapidly than those in the resource-depleted\ncore. Using both analytical arguments and three-dimensional simulations, we\nfind that the proliferation gradients result in flows and in gradients of\nactivity both of which can align the orientation axis of cells inside the\naggregates. Depending on environmental conditions and the intrinsic tissue\nproperties, we identify three distinct alignment regimes: spheroids in which\nall the cells align either radially or tangentially to the surface throughout\nthe aggregate and spheroids with angular cell orientation close to the surface\nand radial alignment in the core. The continuum description of tissue dynamics\ninside spheroids not only allows us to infer dynamic cell parameters from\nexperimentally measured cell alignment profiles, but more generally motivates\nnovel mechanisms for controlling the alignment of cells within aggregates which\nhas been shown to influence the mechanical properties and invasive capabilities\nof tumors."
    },
    {
        "anchor": "Granular segregation under vertical tapping: We present extensive Molecular Dynamics simulations on species segregation in\na granular mixture subject to vertical taps. We discuss how grain properties,\ne.g., size, density, friction, as well as, shaking properties, e.g., amplitude\nand frequency, affect such a phenomenon. Both Brazil Nut Effect (larger\nparticles on the top, BN) and the Reverse Brazil Nut Effect (larger particles\non the bottom, RBN) are found and we derive the system comprehensive\n``segregation diagram'' and the BN to RBN crossover line. We also discuss the\nrole of friction and show that particles which differ only for their frictional\nproperties segregate in states depending on the tapping acceleration and\nfrequency.",
        "positive": "Using a P\u00e9clet Number for the Translocation of Polymer through a\n  Nanopore to Tune Coarse-Grained Simulations to Experimental Conditions: Coarse-grained simulations are often employed to study the translocation of\nDNA through a nanopore. The majority of these studies investigate the\ntranslocation process in a relatively generic sense and do not endeavour to\nmatch any particular set of experimental conditions. In this manuscript, we use\nthe concept of a P\\'eclet number for translocation, $P_t$, to compare the\ndrift-diffusion balance in a typical experiment vs a typical simulation. We\nfind that the standard coarse-grained approach over-estimates diffusion effects\nby anywhere from a factor of 5 to 50 compared to experimental conditions using\ndsDNA. By defining a coarse-graining parameter, $\\lambda$, we are able to\ncorrect this and tune the simulations to replicate the experimental $P_t$ (for\ndsDNA and other scenarios). To show the effect that a particular $P_t$ can have\non the dynamics of translocation, we perform simulations across a wide range of\n$P_t$ values for two different types of driving forces: a force applied in the\npore and a pulling force applied to the end of the polymer. As $P_t$ brings the\nsystem from a diffusion dominated to a drift dominated regime, a variety of\neffects are observed including a non-monotonic dependence of the translocation\ntime $\\tau$ on $P_t$ and a steep rise in the probability of translocating.\nComparing the two force cases illustrates the impact of the crowding effects\nthat occur on the trans side: a non-monotonic dependence of the width of the\n$\\tau$ distributions is obtained for the in-pore force but not for the pulling\nforce."
    },
    {
        "anchor": "Micro-mechanical insights into the stress transmission in strongly\n  aggregating colloidal gel: Predicting the mechanical response of the soft gel materials under external\ndeformation is of paramount importance in many areas, such as foods,\npharmaceuticals, solid-liquid separations, cosmetics, aerogels and drug\ndelivery. Most of the understanding of the elasticity of gel materials is based\non the concept of fractal scaling with very little microscopic insights.\nPrevious experimental observations strongly suggest that the gel material loses\nthe fractal correlations upon deformation and the range of packing fraction up\nto which the fractal scaling can be applied is very limited. Also, correctly\nimplementing the fractal modeling requires identifying the elastic backbone,\nwhich is a formidable task. So far, there is no clear understanding of the gel\nelasticity at high packing fraction and the correct length scale that governs\nits mechanical response. In this work, we undertake extensive numerical\nsimulations to elucidate the different aspects of stress transmission in the\ngel materials. We observe the existence of two percolating networks of\ncompressive and tensile normal forces close to the gel point. We also find that\nthe probability distribution for the compressive and tensile part normalized by\ntheir respective mean shows universal behavior irrespective of varied\ninteraction potential, thermal energy and particle size distribution.\nInterestingly, there are also large number of contacts with zero normal force,\nand consequently, a peak in the normal force distribution is observed at\n$f_n\\approx0$ even at higher pressure. We also identify the critical internal\nstate parameters such as mean normal force, force anisotropies and the average\ncoordination number and propose simple constitutive relations that relate the\ndifferent components of the stress to the internal state parameters. The\nagreement between our model prediction and the simulation observation is\nexcellent.",
        "positive": "Shear Thinning from Bond Orientation in Model Unentangled Bottlebrush\n  Polymer Melts: The rheology of molecular brushes remains challenging to control due to the\nmultiple length scales and relaxation processes involved and the lack of direct\nobservation of molecular conformation during flow. We use molecular dynamics\nsimulations to determine the shear thinning of unentangled bottlebrush polymers\nwith varying architecture, from linear chains to combs, to densely grafted\nbottlebrushes, to star-like and star polymers. We find shear thinning exponents\nin line with theoretical and experimental results and characterize the shape\nand orientation of bottlebrushes in steady-state flow. Many shape parameters\nderived from the gyration tensor show molecular alignment with the flow for all\nsystems. Yet, the orientation of individual bonds is what most strongly\ncorrelates with the architecture-dependent shear-thinning exponents. In densely\ngrafted bottlebrushes, the packing of side chains prevents alignment with the\nflow, causing a reduction in shear thinning. The molecular insight from our\nsimulations is useful to tune the architecture of bottlebrushes to control\ntheir rheology."
    },
    {
        "anchor": "Time dependent current in a nonstationary environment: A microscopic\n  approach: Based on a microscopic system reservoir model,where the associated bath is\nnot in thermal equilibrium, we simulate the nonstationary Langevin dynamics and\nobtained the generalized nonstationary fluctuation dissipation relation (FDR)\nwhich asymptotically reduces to the traditional form. Our Langevin dynamics\nincorporates non-Markovian process also, the origin of which lies on the\ndecaying term of the nonstationary FDR. We then follow the stochastic dynamics\nof the Langevin particle based on the Fokker-Planck-Smoluchowski description,\nin ratchet potential to obtain the steady and time dependent current in an\nanalytic form. We also examine the influence of initial excitation and\nsubsequent relaxation of bath modes on the transport of the Langevin particle\nto show that the nonequilibrium nature of the bath leads to both strong\nnon-exponential dynamics as well as nonstationary current.",
        "positive": "Formation of a hard surface layer during drying of a heated porous media: We report surface hardening or crust formation, unlike caking, during drying\nwhen a confined porous medium was heated from above using IR radiation. These\ncrusts have higher strength than their closest counterparts such as sandcastles\nand mud-peels which essentially are clusters of partially wet porous medium.\nObserved higher strength of the crusts is mostly due to surface tension between\nthe solid particles which are connected by liquid bridges (connate water).\nQualitative (FTIR) and quantitative (TGA) measurements confirm the presence of\ntrapped water within the crust. Amount of the trapped water was ~1.5% (this is\nabout 10 times higher than in the samples with caking) which was confirmed\nusing SEM images. Further, in the fixed particle sizes case, the crust\nthickness varied slightly (10-20 particle diameters only for cases with\nexternal heating) while with the natural sand whole porous column was crusted;\nsurprisingly, crust was also found with the hydrophobic glass beads.\nFluorescein dye visualization technique was used to determine the crust\nthickness. We give a power law relation between the crust thickness and the\nincident heat flux for various particle sizes. The strength of the crust\ndecreases drastically with increasing hydrophilic spheres diameter while it\nincreases with higher surface temperature."
    },
    {
        "anchor": "On a Coarse-Graining Concept in Colloidal Physics with Application to\n  Fluid and Arrested Colloidal Suspensions in Shearing Fields: We poorly understand the macroscopic properties of complex fluids and of\namorphous bodies in general. This is mainly due to the interplay between\nphenomena at different levels and length-scales. In particular, it is not\nnecessarily true that the microscopic level (dominated by direct interactions)\ncoincides with the level where the continuum description comes into play. This\nis typically the case in the presence of structural inhomogeneities which are\ninherent to all structurally disordered states of matter below close packing.\nAs a consequence, the macroscopic response to external fields of either fluid\nor arrested disordered states is not well understood. In order to disentangle\nthis complexity, in this work we build upon a simple yet seemingly powerful\nconcept. This can be summarized as follows: the mesoscopic length-scale of\nstructural inhomogeneities is assumed to be the characteristic length-scale of\nthe effective building blocks, while the degrees of freedom of the primary\nparticles are integrated out. Theoretical results are derived, in the present\nwork, for the macroscopic response of fluid and dynamically arrested model\ncolloidal states in fields of shear. The predictions of the coarse-grained\ntheories and the applicability of the principle are tested in comparison with\noriginal simulation and experimental data.",
        "positive": "Arrest and flow of colloidal glasses: I review recent progress in understanding the arrest and flow behaviour of\ncolloidal glasses, based on mode coupling theory (MCT) and related approaches.\nMCT has had notable recent successes in predicting the re-entrant arrest\nbehaviour of colloids with short range attractions. Developments based upon it\noffer important steps towards calculating, from rational foundations in\nstatistical mechanics, nonlinear flow parameters such as the yield stress of a\ncolloidal glass. An important open question is why MCT works so well."
    },
    {
        "anchor": "Electromagnetic Force and the Maxwell Stress Tensor in Condensed Systems: While the electromagnetic force is microscopically simply the Lorentz force,\nits macroscopic form is more complicated, and given by expressions such as the\nMaxwell stress tensor and the Kelvin force. Their derivation is fairly opaque,\nat times even confusing, and their range of validity all but a well kept\nsecret. These circumstances unnecessarily reduce the usefulness and\ntrustworthiness of some key quantities in macroscopic electrodynamics.\n  This article presents a thorough yet pedagogical derivation of the Maxwell\nstress tensor and electromagnetic force in condensed media. It starts from\nuniversally accepted inputs: conservation laws, thermodynamics and the Maxwell\nequations. Simplifications are considered for various limits, especially the\nequilibrium, with a range of validity assigned to each expression. Some\nwidespread misconceptions are scrutinized, and hidden ambiguities in popular\nnotations revealed.\n  A number of phenomena typical of strongly polarizable systems, especially\nferrofluid, are then considered. In addition to enhancing the appreciation of\nthese systems, it helps to solidify the grasp of the introduced concepts and\nderived formulas, and it demonstrates the ease with which the Maxwell stress\ntensor can be handled, inviting theorists and experimentalists alike to embrace\nthis useful quantity.",
        "positive": "Pressure Induced Enlargement and Ionic Current Rectification in\n  Symmetric Nanopores: Nanopores in solid state membranes are a tool able to probe nanofluidic\nphenomena or can act as a single molecular sensor. They also have diverse\napplications in filtration, desalination or osmotic power generation. Many of\nthese applications involve chemical, or hydrostatic pressure differences, which\nact on both the supporting membrane and the ion transport through the pore. By\nusing pressure differences between the sides of the membrane, and an\nalternating current approach to probe ion transport, we investigate two\ndistinct physical phenomena: the elastic deformation of the membrane through\nthe measurment of strain at the nanopore, and the growth of ionic current\nrectification with pressure due to pore entrance effects."
    },
    {
        "anchor": "Dynamics and stability of dispersions of polyelectrolyte-filled\n  multilayer microcapsules: We report dynamic and coagulation properties of a dispersion of\npolyelectrolyte multilayer microcapsules filled with solutions of a strong\npolyelectrolyte. The capsule self-diffusion coefficient in the vicinity of the\nwall is measured using a particle tracking procedure from confocal images of\nthe dispersion. Our results suggest that the microcapsules take a charge of\nencapsulated polyions, which indicates a semi-permeability of the shell and a\nleakage of counter-ions. The diffusion of capsules in the force field is\nqualitatively similar to that of charged solid particles: The effective\ninteraction potential contains a weak local attractive minimum and an\nelectrostatic barrier. We also found that the aggregation of suspended capsules\noccurs faster than their sedimentation and adhesion onto a glass surface.",
        "positive": "The Influence on Crystal Nucleation of an Order-Disorder Transition\n  among the Subcritical Clusters: Studies of nucleation generally focus on the properties of the critical\ncluster, but the presence of defects within the crystal lattice means that the\npopulation of nuclei necessarily evolve through a distribution of pre-critical\nclusters with varying degrees of structural disorder on their way to forming a\ngrowing stable crystal. To investigate the role pre-critical clusters play in\nnucleation, we develop a simple thermodynamic model for crystal nucleation in\nterms of cluster size and the degree of cluster order that allows us to alter\nthe work of forming the pre-critical clusters without effecting the properties\nof the critical cluster. The steady state and transient nucleation behaviour of\nthe system are then studied numerically, for different microscopic ordering\nkinetics. We find that the models exhibits a generic order-disorder transition\nin the pre-critical clusters. Independent of the type of ordering kinetics,\nincreasing the accessibility of disordered pre-critical clusters decreases both\nthe steady state nucleation rate and the nucleation lag time. Furthermore, the\ninterplay between the free energy surface and the microscopic ordering kinetics\nleads to three distinct nucleation pathways."
    },
    {
        "anchor": "Stochastic Paleoclimatology: Modeling the EPICA Ice Core Climate Records: We analyze and model the stochastic behavior of paleoclimate time series and\nassess the implications for the coupling of climate variables during the\nPleistocene glacial cycles. We examine 800 kyr of carbon dioxide, methane,\nnitrous oxide, and temperature proxy data from the EPICA Dome-C ice core, which\nare characterized by 100~kyr glacial cycles overlain by fluctuations across a\nwide range of time scales. We quantify this behavior through multifractal\ntime-weighted detrended fluctuation analysis, which distinguishes near\nred-noise and white-noise behavior below and above the 100~kyr glacial cycle\nrespectively in all records. This allows us to model each time series as a\none-dimensional periodic non-autonomous stochastic dynamical system, and assess\nthe stability of physical processes and the fidelity of model-simulated time\nseries. We extend this approach to a four-variable model with linear coupling\nterms, which we interpret in terms of the interrelationships between the time\nseries. Methane and nitrous oxide are found to have significant destabilizing\ninfluences, while carbon dioxide and temperature have smaller stabilizing\ninfluences. We draw conclusions about causal relationships in glacial\ntransitions and the climate processes that may have facilitated these\ncouplings, and highlight opportunities to further develop stochastic modeling\napproaches.",
        "positive": "Network of Econophysicists: a weighted network to investigate the\n  development of Econophysics: The development of Econophysics is studied from the perspective of scientific\ncommunication networks. Papers in Econophysics published from 1992 to 2003 are\ncollected. Then a weighted and directed network of scientific communication,\nincluding collaboration, citation and personal discussion, is constructed. Its\nstatic geometrical properties, including degree distribution, weight\ndistribution, weight per degree, and betweenness centrality, give a nice\noverall description of the research works. The way we introduced here to\nmeasure the weight of connections can be used as a general one to construct\nweighted network."
    },
    {
        "anchor": "Connecting packing efficiency of binary hard sphere systems to their\n  intermediate range structure: Using computed x-ray tomography we determine the three dimensional (3d)\nstructure of binary hard sphere mixtures as a function of composition and size\nratio of the particles, q. Using a recently introduced four-point correlation\nfunction we reveal that this 3d structure has on intermediate and large length\nscales a surprisingly regular order, the symmetry of which depends on q. The\nrelated structural correlation length has a minimum at the composition at which\nthe packing fraction is highest. At this composition also the number of\ndifferent local particle arrangements has a maximum, indicating that efficient\npacking of particles is associated with a structure that is locally maximally\ndisordered.",
        "positive": "Hierarchical assembly is more robust than egalitarian assembly in\n  synthetic capsids: Self-assembly of complex and functional materials remains a grand challenge\nin soft material science. Efficient assembly depends on a delicate balance\nbetween thermodynamic and kinetic effects, requiring fine-tuning affinities and\nconcentrations of subunits. By contrast, we introduce an assembly paradigm that\nallows large error-tolerance in the subunit affinity and helps avoid kinetic\ntraps. Our combined experimental and computational approach uses a model system\nof triangular subunits programmed to assemble into T=3 icosahedral capsids\ncomprising 60 units. The experimental platform uses DNA origami to create\nmonodisperse colloids whose 3D geometry is controlled to nanometer precision,\nwith two distinct bonds whose affinities are controlled to kBT precision,\nquantified in situ by static light scattering. The computational model uses a\ncoarse-grained representation of subunits, short-ranged potentials, and\nLangevin dynamics. Experimental observations and modeling reveal that when the\nbond affinities are unequal, two distinct hierarchical assembly pathways occur,\nin which the subunits first form dimers in one case, and pentamers in another.\nThese hierarchical pathways produce complete capsids faster and are more robust\nagainst affinity variation than egalitarian pathways, in which all binding\nsites have equal strengths. This finding suggests that hierarchical assembly\nmay be a general engineering principle for optimizing self-assembly of complex\ntarget structures."
    },
    {
        "anchor": "Scaling of granular column collapses on inclined planes: Granular column collapse is a simple but important problem to the granular\nmaterial community, due to its links to dynamics of natural hazards, such as\nlandslides and pyroclastic flows, and many industrial situations, as well as\nits potential of analyzing transient and non-local rheology of granular flows.\nThis article proposes a new dimensionless number to describe the run-out\nbehaviour of granular columns on inclined planes based on both previous\nexperimental data and dimensional analysis. With the assistance of the\nsphero-polyhedral discrete element method (DEM), we simulate inclined granular\ncolumn collapses with different initial aspect ratios, inter-particle\nfrictions, and initial solid fractions on inclined planes with different\ninclination angles (2.5$^{\\circ}$ - 20.0$^{\\circ}$) to verify the proposed\ndimensional analysis. Detailed analyses are further provided for better\nunderstanding of the influence of different initial conditions and boundary\nconditions, and to help unify the description of the relative run-out distances\nof systems with different inclination angles. This work determines the\nsimilarity and unity between granular column collapses on inclined planes and\nthose on horizontal planes, and helps investigate the transient rheological\nbehaviour of granular flows, which has direct relevance to various natural and\nengineering systems.",
        "positive": "Decoupling between thermodynamics and dynamics during rejuvenation in\n  colloidal glasses: We rejuvenate well-aged quasi-2D binary colloidal glasses by thermal cycling,\nand systematically measure both the statistical responses and particle-level\nstructural evolutions during rejuvenation. While the moduli and boson peak are\ncontinuously rejuvenated with increasing number of cycles, the mean square\ndisplacement (MSD) fluctuates significantly between different groups of thermal\ncycles. The decoupling between the thermodynamical and dynamical evolutions\nsuggests different microscopic origins for different bulk properties of\nglasses. We find that a small fraction of structural rearrangements triggered\nby thermal cycling could alter the whole elastic continuum and lead to the\nsignificant thermodynamic rejuvenation, while localized defects could be\nactivated and deactivated at the positions close to the rearrangements with\nsignificantly high mobility change and hence result in the fluctuated dynamics\neven with only about 10% of particles as fast regions. Our results offer a\ncomprehensive picture for the microscopic mechanisms underlying bulk glass\nrejuvenation, which could be readily used to refine glass properties or to\nformulate further statistical theories in glassy systems."
    },
    {
        "anchor": "Rheological signatures of a glass-glass transition in an aging colloidal\n  clay: The occurrence of non-equilibrium transitions between arrested states has\nrecently emerged as an intriguing issue in the field of soft glassy materials.\nThe existence of one such transition has been suggested for aging colloidal\nclays (Laponite$^{\\circledR}$ suspensions) at weight concentration 3.0%,\nalthough further experimental evidences are necessary to validate this\nscenario. Here, we test the occurrence of this transition for spontaneously\naged (non-rejuvenated) samples, by exploiting the rheological tools of\nDynamical Mechanical Analysis. On imposing consecutive compression cycles to\ndifferently aged clay suspensions, we find that a quite abrupt change of\nrheological parameters occurs for ages around three days. For the Young and\nelastic moduli, the change with the waiting time is essentially independent\nfrom the deformation rate, whereas other \"fluid-like\" properties, such as the\nloss modulus, do clearly display some rate dependence. We also show that the\ncrossover identified by rheology coincides with deviations of the relaxation\ntime (obtained through X-Ray Photon Correlation Spectroscopy) from its expected\nmonotonic increase with aging. Thus, our results robustly support the existence\nof a glass-glass transition in aging colloidal clays, highlighting\ncharacteristic features of of their viscoelastic behaviour.",
        "positive": "Changes in the structure of tethered chain molecules as predicted by\n  density functional approach: We use a version of the density functional theory to study the changes in the\nheight of the tethered layer of chains built of jointed spherical segments with\nthe change of the length and surface density of chains. For the model in which\nthe interactions between segments and solvent molecules are the same as between\nsolvent molecules we have discovered two effects that have not been observed in\nprevious studies. Under certain conditions and for low surface concentrations\nof the chains, the height of the pinned layer may attain a minimum. Moreover,\nfor some systems we observe that when the temperature increases, the height of\nthe layer of chains may decrease."
    },
    {
        "anchor": "Thin-sheet creation and threshold pressures in drop splashing: A liquid drop impacting a smooth solid substrate splashes by emitting a thin\nliquid sheet from near the contact line of the spreading liquid. This sheet is\nlifted from the substrate and ultimately breaks apart. Surprisingly, the splash\nis caused by the ambient gas, whose properties dictate when and if the sheet is\ncreated. Here I focus on two aspects of this process. Using high-speed imaging\nI find that the time of thin-sheet creation displays a different quantitative\ndependence on air pressure if the sheet is created during the early stages of\nspreading, rather than when the liquid has already spread to a large radius.\nThis result sheds light on previously observed impact velocity regimes.\nAdditionally, by measuring impacts of drops on surfaces comprised of both rough\nand smooth regions, I identify a new threshold velocity that limits the times\nat which the thin sheet can be created. This velocity determines the threshold\npressure below which splashing is suppressed.",
        "positive": "Hydrodynamic coupled modes of a nematic under a temperature gradient and\n  a uniform gravitational field: Fluctuating hydrodynamics (FH) describes the dynamics of the fluctuations for\nfluids at mesoscopic scales. Here we use this approach to study the\nfluctuations of the hydrodynamic variables of a thermotropic nematic liquid\ncrystal (NLC) in a nonequilibrium steady state (NESS). This state is induced by\nan externally imposed temperature gradient and a uniform gravity field. We\ncalculate analytically both, the equilibrium and nonequilibrium hydrodynamic\nmodes. We find that in this NESS the nonequilibrium effects produced by the\nexternal gradients only affect the longitudinal variables. This gives rise to a\npair of sound modes, one orientation mode of the director and two visco-heat\nmodes formed by the coupling of the shear and thermal modes. We also find that\nthe last three modes exhibit the largest changes. The analytical expressions\nthat we have found for the visco-heat modes imply that the heat and shear modes\nof the NLC are coupled, that they reduce to those of simple fluid in the\nisotropic limit and that these modes may become propagative, a feature that\nalso occurs in the simple fluid. In the isotropic limit of the nematic our\nresults also reduce to the hydrodynamic modes of a simple fluid in the presence\nof the same temperature gradient and the pressure gradient produced by the\ngravity field."
    },
    {
        "anchor": "Self-diffusion of a sphere in an effective medium of rods: Self-diffusion of a sphere in a network of rods is analyzed theoretically.\nHydrodynamic interactions are taken into account according to the model of\nDhont et al., under the assumption that $\\ka << 1$ and $\\bar{a}/L<<1$, where\n$1/\\kappa$ is the network hydrodynamic screening length, $\\bar{a}=a+D/2$, and\n$a$ is the sphere radius, while $D$ and $L$ are the diameter and length of a\nrod, respectively. Simple expressions for the diffusion coefficients are\nderived and shown to be independent of $L$.",
        "positive": "The effect of geometrical confinement on the interaction between charged\n  colloidal suspensions: The effective interaction between charged colloidal particles confined\nbetween two planar like-charged walls is investigated using computer\nsimulations of the primitive model describing asymmetric electrolytes. In\ndetail, we calculate the effective force acting onto a single macroion and onto\na macroion pair in the presence of slit-like confinement. For moderate Coulomb\ncoupling, we find that this force is repulsive. Under strong coupling\nconditions, however, the sign of the force depends on the distance to the\nplates and on the interparticle distance. In particular, the particle-plate\ninteraction becomes strongly attractive for small distances which may explain\nthe occurrence of colloidal crystalline layers near the plates observed in\nrecent experiments."
    },
    {
        "anchor": "A relaxation constant in the folding of thin viscoelastic sheets: If one folds a thin viscoelastic sheet under an applied force, a line of\nplastic deformation is formed which shapes the sheet into an angle. We\ndetermine the parameters that define this angle experimentally and show that,\nno matter how much load one applies, it is impossible to make angles less than\na certain minimum angle in a definite time. Moreover, it is shown that\nregardless of whether the sheet is released freely afterward or kept under the\nload, a logarithmic relaxation process follows the first deformation. The slope\nof this logarithm is the same in both conditions and depends neither on the\napplied force nor on the thickness of the sheet, which indicates it is directly\na probe of the molecular mobility of the material. This intrinsic relaxation\nconstant was measured 0.01 and 5.7 for Mylar and paper sheets, respectively. It\nis also suggested that the observed minimum angle of folding can be defined as\na characteristic index for the plasticity of different materials.",
        "positive": "Instabilities and shape variation phase transitions in tubular lipid\n  membranes: Changes of external parameters in proximity of critical point can increase\nthermal fluctuations of tubular lipid membrane (TLM) and result in variation of\nthe membrane shape. The phase transitions in the system are shown to be\ncontrolled by a single effective parameter, which depends on the pressure\ndifference between inner and outer regions of membrane and the applied\nstretching force. We determine an interval of the parameter values\ncorresponding to the stability region of the cylindrical shape of TLM and\ninvestigate the behavior of the system in the vicinity of critical\ninstabilities, where the cylindrical shape of membrane becomes unstable with\nrespect to thermal fluctuations. The applied boundary conditions strongly\ninfluence the behavior of TLM. For example, small negative effective parameter\ncorresponds to chiral shape of TLM only in the case of periodic boundary\nconditions. We also discuss other three types of phase transitions emerging in\nthe system."
    },
    {
        "anchor": "Interstitial gas and density-segregation in vertically-vibrated granular\n  media: We report experimental studies of the effect of interstitial gas on\nmass-density-segregation in a vertically-vibrated mixture of equal-sized bronze\nand glass spheres. Sufficiently strong vibration in the presence of\ninterstitial gas induces vertical segregation into sharply separated bronze and\nglass layers. We find that the segregated steady state (i.e., bronze or glass\nlayer on top) is a sensitive function of gas pressure and viscosity, as well as\nvibration frequency and amplitude. In particular, we identify distinct regimes\nof behavior that characterize the change from bronze-on-top to glass-on-top\nsteady-state.",
        "positive": "Tracer diffusion of hard-sphere binary mixtures under nano-confinement: The physics of diffusion phenomena in nano and micro channels has attracted a\nlot of attention in recent years, due to its close connection with many\ntechnological, medical and industrial applications. In the present paper we\nemploy a kinetic approach to investigate how the confinement in nanostructured\ngeometries affects the diffusive properties of fluid mixtures and leads to the\nappearance of properties different from those of bulk systems. In particular,\nwe derive an expression for the friction tensor in the case of a bulk fluid\nmixture confined to a narrow slit having undulated walls. The boundary\nroughness leads to a new mechanism for transverse diffusion, and can even lead\nto an effective diffusion along the channel larger than the one corresponding\nto a planar channel of equivalent section. Finally we discuss a reduction of\nthe previous equation to a one dimensional effective diffusion equation in\nwhich an entropic term encapsulates the geometrical information on the channel\nshape."
    },
    {
        "anchor": "Facilitation of DNA loop formation by protein-DNA non-specific\n  interactions: Complex DNA topological structures, including polymer loops, are frequently\nobserved in biological processes when protein molecules simultaneously bind to\nseveral distant sites on DNA. However, the molecular mechanisms of formation of\nthese systems remain not well understood. Existing theoretical studies focus\nonly on specific interactions between protein and DNA molecules at target\nsequences. However, the electrostatic origin of primary protein-DNA\ninteractions suggests that interactions of proteins with all DNA segments\nshould be considered. Here we theoretically investigate the role of\nnon-specific interactions between protein and DNA molecules on the dynamics of\nloop formation. Our approach is based on analyzing a discrete-state stochastic\nmodel via a method of first-passage probabilities supplemented by Monte Carlo\ncomputer simulations. It is found that depending on a protein sliding length\nduring the non-specific binding event three different dynamic regimes of the\nDNA loop formation might be observed. In addition, the loop formation time\nmight be optimized by varying the protein sliding length, the size of the DNA\nmolecule, and the position of the specific target sequences on DNA. Our results\ndemonstrate the importance of non-specific protein-DNA interactions in the\ndynamics of DNA loop formations. Several quantitative predictions that can be\nexperimentally tested are also presented.",
        "positive": "Optimizing fog harvesting by biomimicry: Inspired by the stenocara beetle, we study an ideal flat surface composed of\na regular array of hydrophilic circular patches in a hydrophobic matrix on an\nincline of tilt $\\alpha$ with respect to the horizontal. Based on an exact\nsolution of the Laplace-Young equation at first order in the Bond number, the\nliquid storage capacity of the surface is maximized as function of the patch\nradius, for suitable ranges of hydrophilic and hydrophobic contact angles, for\ntilt angles such as $45^{\\circ}$ or $90^\\circ$. It is found that the optimal\nradius equally prevents dewetting from the top of the patches and overflow at\nthe bottom. These theoretical considerations are validated by several\nexperiments for the glass/octadecyltrichlorosilane (OTS) system involving\ndifferent patch sizes and different inclinations. In a simple dynamical model,\ntaking into account the flux of fog onto the surface or condensation on a\nsuitably cooled surface, we find that the conditions for maximum harvest agree\nwith the ones of maximum static storage. The method could be developed for drop\nstorage and drop transport applications such as water-harvesting systems."
    },
    {
        "anchor": "Continuum approach to wide shear zones in quasi-static granular matter: Slow and dense granular flows often exhibit narrow shear bands, making them\nill-suited for a continuum description. However, smooth granular flows have\nbeen shown to occur in specific geometries such as linear shear in the absence\nof gravity, slow inclined plane flows and, recently, flows in split-bottom\nCouette geometries. The wide shear regions in these systems should be amenable\nto a continuum description, and the theoretical challenge lies in finding\nconstitutive relations between the internal stresses and the flow field. We\npropose a set of testable constitutive assumptions, including\nrate-independence, and investigate the additional restrictions on the\nconstitutive relations imposed by the flow geometries. The wide shear layers in\nthe highly symmetric linear shear and inclined plane flows are consistent with\nthe simple constitutive assumption that, in analogy with solid friction, the\neffective-friction coefficient (ratio between shear and normal stresses) is a\nconstant. However, this standard picture of granular flows is shown to be\ninconsistent with flows in the less symmetric split-bottom geometry - here the\neffective friction coefficient must vary throughout the shear zone, or else the\nshear zone localizes. We suggest that a subtle dependence of the\neffective-friction coefficient on the orientation of the sliding layers with\nrespect to the bulk force is crucial for the understanding of slow granular\nflows.",
        "positive": "Depinning and heterogeneous dynamics of colloidal crystal layers under\n  shear flow: Using Brownian dynamics (BD) simulations and an analytical approach we\ninvestigate the shear-induced, nonequilibrium dynamics of dense colloidal\nsuspensions confined to a narrow slit-pore. Focusing on situations where the\ncolloids arrange in well-defined layers with solidlike in-plane structure, the\nconfined films display complex, nonlinear behavior such as collective depinning\nand local transport via density excitations. These phenomena are reminiscent of\ncolloidal monolayers driven over a periodic substrate potential. In order to\ndeepen this connection, we present an effective model which maps the dynamics\nof the shear-driven colloidal layers to the motion of a single particle driven\nover an effective substrate potential. This model allows to estimate the\ncritical shear rate of the depinning transition based on the equilibrium\nconfiguration, revealing the impact of important parameters such as the\nslit-pore width and the interaction strength. We then turn to heterogeneous\nsystems where a layer of small colloids is sheared with respect to bottom\nlayers of large particles. For these incommensurate systems we find that the\nparticle transport is dominated by density excitations resembling the so-called\n\"kink\" solutions of the Frenkel-Kontorova (FK) model. In contrast to the FK\nmodel, however, the corresponding \"antikinks\" do not move."
    },
    {
        "anchor": "Interplay of rearrangements, strain, and local structure during\n  avalanche propagation: Jammed soft disks exhibit avalanches of particle rearrangements under\nquasistatic shear. We follow the avalanches using steepest descent to decompose\nthem into individual localized rearrangements. We characterize the local\nstructural environment of each particle by a machine-learned quantity,\nsoftness, designed to be highly correlated with rearrangements, and analyze the\ninterplay between softness, rearrangements and strain. Our findings form the\nfoundation of an augmented elastoplastic model that includes local structure.",
        "positive": "Thermodynamic Capacity of a Protein: We show that a protein can be trained to recognise multiple conformations,\nanalogous to an associative memory, and provide capacity calculations based on\nenergy fluctuations and information theory. Unlike the linear capacity of a\nHopfield network, the number of conformations which can be remembered by a\nprotein sequence depends on the size of the amino acid alphabet as ln A,\nindependent of protein length. This admits the possibility of certain proteins,\nsuch as prions, evolving to fold to independent stable conformations, as well\nas novel possibilities for protein and heteropolymer design."
    },
    {
        "anchor": "Ab initio molecular dynamics simulations of Aluminum solvation: The solvation of Al and its hydrolyzed species in water clusters has been\nstudied by means of ab initio molecular dynamics simulations. The hexa-hydrate\naluminum ion formed a stable complex in the finite temperature cluster\nsimulation of one aluminum ion and 16 waters. The average dipole moment of\nstrongly polarized hydrated water molecules in the first solvation shell of the\nhexa-hydrate aluminum ion was found to be 5.02 Debye. The deprotonated\nhexa-hydrate complex evolves into a tetra-coordinated aluminate ion with two\nwater molecules in the second solvation shell forming hydrogen bonds to the\nhydroxyl groups in agreement with the observed coordination.",
        "positive": "Quasi-Chemical and Structural Analysis of Polarizable Anion Hydration: Quasi-chemical theory is utilized to analyze the roles of solute polarization\nand size in determining the structure and thermodynamics of bulk anion\nhydration for the Hofmeister series Cl$^-$, Br$^-$, and I$^-$. Excellent\nagreement with experiment is obtained for whole salt hydration free energies\nusing the polarizable AMOEBA force field. The quasi-chemical approach exactly\npartitions the solvation free energy into inner-shell, outer-shell packing, and\nouter-shell long-ranged contributions by means of a hard-sphere condition.\nSmall conditioning radii, even well inside the first maximum of the\nion-water(oxygen) radial distribution function, result in Gaussian behavior for\nthe long-ranged contribution that dominates the ion hydration free energy. The\nspatial partitioning allows for a mean-field treatment of the long-ranged\ncontribution, leading to a natural division into first-order electrostatic,\ninduction, and van der Waals terms. The induction piece exhibits the strongest\nion polarizability dependence, while the larger-magnitude first-order\nelectrostatic piece yields an opposing but weaker polarizability dependence. In\naddition, a structural analysis is performed to examine the solvation\nanisotropy around the anions. As opposed to the hydration free energies, the\nsolvation anisotropy depends more on ion polarizability than on ion size:\nincreased polarizability leads to increased anisotropy. The water dipole\nmoments near the ion are similar in magnitude to bulk water, while the ion\ndipole moments are found to be significantly larger than those observed in\nquantum mechanical studies. Possible impacts of the observed over-polarization\nof the ions on simulated anion surface segregation are discussed."
    },
    {
        "anchor": "Electrostatic Contribution to the Persistence Length of a Semiflexible\n  Dipolar Chain: We investigate the electrostatic contribution to the persistence length of a\nsemiflexible polymer chain whose segments interact via a screened Debye-H\\\"\nuckel dipolar interaction potential. We derive the expressions for the\nrenormalized persistence length on the level of a 1/D-expansion method already\nsuccessfully used in other contexts of polyelectrolye physics. We investigate\ndifferent limiting forms of the renormalized persistence length of the dipolar\nchain and show that in general it depends less strongly on the screening length\nthan in the context of a monopolar chain. We show that for a dipolar chain the\nelectrostatic persistence length in the same regime of the parameter phase\nspace as the original Odijk-Skolnick-Fixman (OSF) form for a monopolar chain\ndepends logarithmically on the screening length rather than quadratically. This\ncan be understood solely on the basis of a swifter decay of the dipolar\ninteractions with separation compared to the monopolar electrostatic\ninteractions. We comment also on the general contribution of higher multipoles\non the electrostatic renormalization of the bending rigidity.",
        "positive": "The generalized Clapeyron equation and its application to confined ice\n  growth: Most theoretical descriptions of stresses induced by freezing are rooted in\nthe (generalized) Clapeyron equation, which predicts the pressure that a solid\ncan exert as it cools below its melting temperature. This equation is central\nfor topics ranging beyond glaciology to geomorphology, civil engineering, food\nstorage, and cryopreservation. However, it has inherent limitations, requiring\nisotropic solid stresses and conditions near bulk equilibrium. Here, we examine\nwhen the Clapeyron equation is applicable by providing a rigorous derivation\nthat details all assumptions. We demonstrate the natural extension for\nanisotropic stress states, and we show how the temperature and pressure ranges\nfor validity depend on well-defined material properties. Finally, we\ndemonstrate how the range of applicability of the (linear) Clapeyron equation\ncan be extended by adding higher-order terms, yielding results that are in good\nagreement with experimental data for the pressure melting of ice."
    },
    {
        "anchor": "Sharing the load: stress redistribution governs fracture of polymer\n  double networks: The stress response of polymer double networks depends not only on the\nproperties of the constituent networks, but also on the interactions arising\nbetween them. Here we demonstrate, via coarse-grained simulations, that both\ntheir global stress response and their microscopic fracture mechanics are\ngoverned by load sharing through these inter-network interactions. By comparing\nour results with affine predictions, where stress redistribution is by\ndefinition homogeneous, we show that stress redistribution is highly\ninhomogeneous. In particular, the affine prediction overestimates the fraction\nof broken chains by almost an order of magnitude. Furthermore, homogeneous\nstress distribution predicts a single fracture process, while in our\nsimulations fracture of sacrificial chains takes place in two steps governed by\nload sharing within a network and between networks, respectively. Our results\nthus provide a detailed microscopic picture of how inhomogeneous stress\nredistribution after rupture of chains governs the fracture of polymer double\nnetworks.",
        "positive": "Purely viscous acoustic propulsion of bimetallic rods: Synthetic microswimmers offer models for cell motility and their tunability\nmakes them promising candidates for biomedical applications. Here we measure\nthe acoustic propulsion of bimetallic micro-rods that, when trapped at the\nnodal plane of a MHz acoustic resonator, swim with speeds of up to 300 microns\nper second. While past acoustic streaming models predict speeds that are more\nthan one order of magnitude smaller than our measurements, we demonstrate that\nthe acoustic locomotion of the rods is driven by a viscous, non-reciprocal\nmechanism relying on shape anisotropy akin to that used by swimming cells and\nthat reproduces our data with no adjustable parameters."
    },
    {
        "anchor": "\"Double swallow-tail\" singularity and glass-glass transition in a\n  quasibinary system: The system with the square shoulder (SS) potential is considered in the frame\nof Mode Coupling Theory (MCT) approach. An approximation for the structure\nfactor is used that emphasizes the quasibinary character of the system. The\nqualitative phase diagram is constructed that includes continuous and\ndiscontinuous glass-glass transitions. The phase diagram is governed by two\nswallow tails connected with two $A_4$ singularities.",
        "positive": "Interfacial instabilities in confined displacements involving\n  non-Newtonian fluids: The growth of interfacial instabilities during fluid displacements can be\ndriven by gradients in pressure, viscosity and surface tension, and by applying\nexternal fields. Since displacements of non-Newtonian fluids such as polymer\nsolutions, colloidal and granular slurries are ubiquitous in natural and\nindustrial processes, understanding the growth mechanisms and fully-developed\nmorphologies of interfacial patterns involving non-Newtonian fluids is\nextremely important. In this perspective, we focus on {displacement\nexperiments} wherein competition{s} between capillary, viscous, elastic and\nfrictional forces drive the onset and growth of interfacial instabilities in\nconfined geometries. We conclude by highlighting several exciting open problems\nin this research area."
    },
    {
        "anchor": "Micropipette aspiration method for characterizing biological materials\n  with surface energy: Many soft biological tissues possess a considerable surface stress, which\nplays a significant role in their biophysical functions, but most previous\nmethods for characterizing their mechanical properties have neglected the\neffects of surface stress. In this work, we investigate the micropipette\naspiration to measure the mechanical properties of cells and soft tissues with\nsurface effects. The neo-Hookean constitutive model is adopted to describe the\nhyperelasticity of the measured biological material, and the surface effect is\nconsidered through the finite element method. It is found that when the pipette\nradius or aspiration length is comparable to the elastocapillary length,\nsurface energy may distinctly alter the aspiration response. Generally, both\nthe aspiration length and the bulk normal stress decreases as surface energy\nincreases, and thus neglecting the surface energy will lead to an\noverestimation of elastic modulus. Through dimensional analysis and numerical\nsimulations, we provide an explicit relation between the imposed pressure and\nthe aspiration length. This method can be applied to accurately determine the\nmechanical properties of soft biological tissues and organs, e.g., tumors and\nembryos.",
        "positive": "Kinetic phase diagram for nucleation and growth of competing crystal\n  polymorphs in charged colloidal suspensions: We determine the full kinetic phase diagram for nucleation and growth of\ncrystal phases in a suspension of charged colloids. We calculate nucleation\nbarrier heights for face-centered cubic (fcc) and body-centered cubic (bcc)\ncrystal phases for varying screening lengths and supersaturations using the\nseeding approach in extensive simulations. Using classical nucleation theory,\nwe determine for the entire metastable fluid region the crystal polymorph with\nthe lowest nucleation barrier. Surprisingly, we find a regime close to the\ntriple point where metastable bcc can form due to a lower nucleation barrier,\neven though fcc is the stable phase. For higher supersaturation, we find that\nthe difference in barrier heights decreases and we observe a mix of hexagonal\nclose-packed (hcp), fcc and bcc structures in the growth of crystalline seeds\nas well as in spontaneously formed crystals."
    },
    {
        "anchor": "Stress controls the mechanics of collagen networks: Collagen is the main structural and load-bearing element of various\nconnective tissues, where it forms the extracellular matrix that supports\ncells. It has long been known that collagenous tissues exhibit a highly\nnonlinear stress-strain relationship (Fung YC, Am J Physiol 213(6),1967;\nHumphrey JD, Proc R Soc Lond A: Math Phys Eng Sci 459(2029),2003), although the\norigins of this nonlinearity remain unknown (McMahon TA, Lec Math Life Sci\n13,1980). Here, we show that the nonlinear stiffening of reconstituted type I\ncollagen networks is controlled by the applied stress, and that the network\nstiffness becomes surprisingly insensitive to network concentration. We\ndemonstrate how a simple model for networks of elastic fibers can\nquantitatively account for the mechanics of reconstituted collagen networks.\nOur model points to the important role of normal stresses in determining the\nnonlinear shear elastic response, which can explain the approximate exponential\nrelationship between stress and strain reported for collagenous tissues (Fung\nYC, Am J Physiol 213(6),1967). This further suggests new principles for the\ndesign of synthetic fiber networks with collagen-like properties, as well as a\nmechanism for the control of the mechanics of such networks.",
        "positive": "Phase behavior of ionic liquid crystals: Bulk properties of ionic liquid crystals are investigated using density\nfunctional theory. The liquid crystal molecules are represented by ellipsoidal\nparticles with charges located in their center or at their tails. Attractive\ninteractions are taken into account in terms of the Gay-Berne pair potential.\nRich phase diagrams involving vapor, isotropic and nematic liquid, as well as\nsmectic phases are found. The dependence of the phase behavior on various\nparameters such as the length of the particles and the location of charges on\nthe particles is studied."
    },
    {
        "anchor": "Evidence of coexistence of change of caged dynamics at Tg and the\n  dynamic transition at Td in solvated proteins: Mossbauer spectroscopy and neutron scattering measurements on proteins\nembedded in solvents including water and aqueous mixtures have emphasized the\nobservation of the distinctive temperature dependence of the atomic mean square\ndisplacements, <u2>, commonly referred to as the dynamic transition at some\ntemperature Td. At low temperatures, <u2> increases slowly, but it assume\nstronger temperature dependence after crossing Td, which depends on the\ntime/frequency resolution of the spectrometer. Various authors have made\nconnection of the dynamics of solvated proteins including the dynamic\ntransition to that of glass-forming substances. Notwithstanding, no connection\nis made to the similar change of temperature dependence of <u2> obtained by\nquasielastic neutron scattering when crossing the glass transition temperature\nTg, generally observed in inorganic, organic and polymeric glass-formers.\nEvidences are presented to show that such change of the temperature dependence\nof <u2> from neutron scattering at Tg is present in hydrated or solvated\nproteins, as well as in the solvents used unsurprisingly since the latter is\njust another organic glass-formers. The <u2> obtained by neutron scattering at\nnot so low temperatures has contributions from the dissipation of molecules\nwhile caged by the anharmonic intermolecular potential at times before\ndissolution of cages by the onset of the Johari-Goldstein beta-relaxation. The\nuniversal change of <u2> at Tg of glass-formers had been rationalized by\nsensitivity to change in volume and entropy of the beta-relaxation, which is\npassed onto the dissipation of the caged molecules and its contribution to\n<u2>. The same rationalization applies to hydrated and solvated proteins for\nthe observed change of <u2> at Tg.",
        "positive": "Multiple yielding processes in a colloidal gel under large amplitude\n  oscillatory stress: Fatigue refers to the changes in material properties caused by repeatedly\napplied loads. It has been widely studied for, e.g., construction materials,\nbut much less has been done on soft materials. Here, we characterize the\nfatigue dynamics of a colloidal gel. Fatigue is induced by large amplitude\noscillatory stress (LAOStress), and the local displacements of the gel are\nmeasured through high-frequency ultrasonic imaging. We show that fatigue\neventually leads to rupture and fluidization. We evidence four successive steps\nassociated with these dynamics: (i) the gel first remains solid, (ii) it then\nslides against the walls, (iii) the bulk of the sample becomes heterogeneous\nand displays solid-fluid coexistence, and (iv) it is finally fully fluidized.\nIt is possible to homogeneously scale the duration of each step with respect to\nthe stress oscillation amplitude $\\sigma_0$. The data are compatible with both\nexponential and power-law scalings with $\\sigma_0$, which hints at two possible\ninterpretations in terms of delayed yielding in terms activated processes or of\nthe Basquin law. Surprisingly, we find that the model parameters behave\nnonmonotonically as we change the oscillation frequency and/or the gel\nconcentration."
    },
    {
        "anchor": "Microscopic interactions and emerging elasticity in model soft\n  particulate gels: We discuss a class of models for particulate gels in which the particle\ncontacts are described by an effective interaction combining a two-body\nattraction and a three-body angular repulsion. Using molecular dynamics, we\nshow how varying the model parameters allows us to sample, for a given gelation\nprotocol, a variety of gel morphologies. For a specific set of the model\nparameters, we identify the local elastic structures that get interlocked in\nthe gel network. Using the analytical expression of their elastic energy from\nthe microscopic interactions, we can estimate their contribution to the\nemergent elasticity of the gel and gain new insight into its origin.",
        "positive": "Water permeation through stratum corneum lipid bilayers from atomistic\n  simulations: Stratum corneum, the outermost layer of skin, consists of keratin filled\nrigid non-viable corneocyte cells surrounded by multilayers of lipids. The\nlipid layer is responsible for the barrier properties of the skin. We calculate\nthe excess chemical potential and diffusivity of water as a function of depth\nin lipid bilayers with compositions representative of the stratum corneum using\natomistic molecular dynamics simulations. The maximum in the excess free energy\nof water inside the lipid bilayers is found to be twice that of water in\nphospholipid bilayers at the same temperature. Permeability, which decreases\nexponentially with the free energy barrier, is reduced by several orders of\nmagnitude as compared to with phospholipid bilayers. The average time it takes\nfor a water molecule to cross the bilayer is calculated by solving the\nSmoluchowski equation in presence of the free energy barrier. For a bilayer\ncomposed of a 2:2:1 molar ratio of ceramide NS 24:0, cholesterol and free fatty\nacid 24:0 at 300K, we estimate the permeability P=3.7e-9 cm/s and the average\ncrossing time \\tau_{av}=0.69 ms. The permeability is about 30 times smaller\nthan existing experimental results on mammalian skin sections."
    },
    {
        "anchor": "Comparison between Classical-Gas behaviours and Granular-Gas ones in\n  micro-gravity: Recent vibration experiments in microgravity are re-examined. We show that\nthey demonstrate that \"granular-gas\" state exists only in the Knudsen regime,\nthat its excitation is \"supersonic\" and that the probability density function\nof the pressure of the gas scales as (Af) to the power 3/2, with A and f being\nthe excitation amplitude and frequency. This paper pursues the description of\nthe experimental results. Then, it compares these ones to what can be predicted\nfrom few simple modelling, which are (i) the classical-gas theory and (ii) the\nthermodynamics of a single particle in a 1d box. The anomalous scaling of\npressure fluctuations (Af) to the 3/2 is explained by the crossover from the\nregime of a single collision during the sampling time, which imposes p scales\nas_ (Af) at small speed, to a multiple collision imposing p scales as_(Af)_ .\nAir effect and effect of g-jitter are discussed and quantified. Influence of\ngrain-grain collisions is described on the distribution of speed. Pacs # : 5.40\n; 45.70 ; 62.20 ; 83.70.Fn",
        "positive": "Sphere penetration by impact in a granular medium: A collisional process: The penetration by a gravity driven impact of a solid sphere into a granular\nmedium is studied by two-dimensional simulations. The scaling laws observed\nexperimentally for both the final penetration depth and the stopping time with\nthe relevant physical parameters are here recovered numerically without the\nconsideration of any solid friction. Collisional processes are thus found as\nessential in explaining the physics of the qualitatively observed phenomena\nwhereas frictional processes can only be considered as secondary effects in the\ngranular penetration by impact."
    },
    {
        "anchor": "Direct observation of twist mode in electroconvection in I52: I report on the direct observation of a uniform twist mode of the director\nfield in electroconvection in I52. Recent theoretical work suggests that such a\nuniform twist mode of the director field is responsible for a number of\nsecondary bifurcations in both electroconvection and thermal convection in\nnematics. I show here evidence that the proposed mechanisms are consistent with\nbeing the source of the previously reported SO2 state of electroconvection in\nI52. The same mechanisms also contribute to a tertiary Hopf bifurcation that I\nobserve in electroconvection in I52. There are quantitative differences between\nthe experiment and calculations that only include the twist mode. These\ndifferences suggest that a complete description must include effects described\nby the weak-electrolyte model of electroconvection.",
        "positive": "Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance: We have observed Bose-Einstein condensation of pairs of fermionic atoms in an\nultracold ^6Li gas at magnetic fields above a Feshbach resonance, where no\nstable ^6Li_2 molecules would exist in vacuum. We accurately determined the\nposition of the resonance to be 822+-3 G. Molecular Bose-Einstein condensates\nwere detected after a fast magnetic field ramp, which transferred pairs of\natoms at close distances into bound molecules. Condensate fractions as high as\n80% were obtained. The large condensate fractions are interpreted in terms of\npre-existing molecules which are quasi-stable even above the two-body Feshbach\nresonance due to the presence of the degenerate Fermi gas."
    },
    {
        "anchor": "Topological metastability of textures in biaxial nematics: We consider textures of biaxial nematics confined between two parallel\nplates. The boundary conformations at the bordering plates are supposed to be\nidentical, the gradients of the order parameter being generally nonzero. We\nclaim that for any texture (including stable uniform order parameter alignment)\nthere exists its counterpart texture which is also a minimum of the gradient\nelastic energy. Our arguments are based on the topological analysis of the\nconformation of the order parameter.",
        "positive": "Polymer Crystallization in 25 nm Spheres: Crystallization within the discrete spheres of a block copolymer mesophase\nwas studied by time-resolved x-ray scattering. The cubic packing of\nmicrodomains, established by self-assembly in the melt, is preserved throughout\ncrystallization by strong interblock segregation even though the amorphous\nmatrix block is well above its glass transition temperature. Homogeneous\nnucleation within each sphere yields isothermal crystallizations which follow\nfirst-order kinetics, contrasting with the sigmoidal kinetics normally\nexhibited in the quiescent crystallization of bulk polymers."
    },
    {
        "anchor": "Simulation of Flow of Mixtures Through Anisotropic Porous Media using a\n  Lattice Boltzmann Model: We propose a description for transient penetration simulations of miscible\nand immiscible fluid mixtures into anisotropic porous media, using the lattice\nBoltzmann (LB) method. Our model incorporates hydrodynamic flow, diffusion,\nsurface tension, and the possibility for global and local viscosity variations\nto consider various types of hardening fluids. The miscible mixture consists of\ntwo fluids, one governed by the hydrodynamic equations and one by diffusion\nequations. We validate our model on standard problems like Poiseuille flow, the\ncollision of a drop with an impermeable, hydrophobic interface and the\ndeformation of the fluid due to surface tension forces. To demonstrate the\napplicability to complex geometries, we simulate the invasion process of\nmixtures into wood spruce samples.",
        "positive": "How does a thermal binary crystal break under shear?: When exposed to strong shearing, the particles in a crystal will rearrange\nand ultimately, the crystal will break by forming large nonaffine defects. Even\nfor the initial stage of this process, only little effort has been devoted to\nthe understanding of the breaking process on the scale of the individual\nparticle size for thermalized mixed crystals. Here, we explore the\nshear-induced breaking for an equimolar two-dimensional binary model crystal\nwith a high interaction asymmetry between the two different species such that\nthe initial crystal has an intersecting square sublattice of the two\nconstituents. Using Brownian dynamics computer simulations, we show that the\ncombination of shear and thermal fluctuations leads to a characteristic\nhierarchical breaking scenario where initially, the more strongly coupled\nparticles are thermally distorted, paving the way for the weakly coupled\nparticles to escape from their cage. This in turn leads to mobile defects which\nmay finally merge, proliferating a cascade of defects, which triggers the final\nbreakage of the crystal. This scenario is in marked contrast to the breakage of\none-component crystals close to melting. Moreover, we explore the orientational\ndependence of the initial shear direction relative to the crystal orientation\nand compare this to the usual melting scenario without shear. Our results are\nverifiable in real-space experiments of superparamagnetic colloidal mixtures at\na pending air-water interface in an external magnetic field where the shear can\nbe induced by an external laser field."
    },
    {
        "anchor": "Creation of a monopole in a spinor condensate: We propose a method to create a monopole structure in a spin-1 spinor\ncondensate by applying the basic methods used to create vortices and solitons\nexperimentally in single-component condensates. We show, however, that by using\na two-component structure for a monopole, we can simplify our proposed\nexperimental approach and apply it also to ferromagnetic spinor condensates. We\nalso discuss the observation and dynamics of such a monopole structure, and\nnote that the dynamics of the two-component monopole differs from the dynamics\nof the three-component monopole.",
        "positive": "Equilibrium cluster formation and gelation: We study the formation and growth of equilibrium clusters in a suspension of\nweakly-charged colloidal particles and small non-adsorbing polymers. The\neffective potential is characterised by a short-range attraction and a\nlong-range repulsion. The size, shape and local structure of the clusters are\nstudied using three-dimensional particle microscopy. We observe a rapid growth\nin the mean cluster size and the average number of nearest neighbours\napproaching the gel boundary."
    },
    {
        "anchor": "The robust assembly of small symmetric nano-shells: Highly symmetric nano-shells are found in many biological systems, such as\nclathrin cages and viral shells. Several studies have shown that symmetric\nshells appear in nature as a result of the free energy minimization of a\ngeneric interaction between their constituent subunits. We examine the physical\nbasis for the formation of symmetric shells, and using a minimal model we\ndemonstrate that these structures can readily grow from identical subunits\nunder non equilibrium conditions. Our model of nano-shell assembly shows that\nthe spontaneous curvature regulates the size of the shell while the mechanical\nproperties of the subunit determines the symmetry of the assembled structure.\nUnderstanding the minimum requirements for the formation of closed nano-shells\nis a necessary step towards engineering of nano-containers, which will have far\nreaching impact in both material science and medicine.",
        "positive": "Further Evidences for Spin Glass like behavior in NiO nanoparticles: Nickel oxide nanoparticles are prepared by a sol gel method and characterized\nby x-ray diffraction and transmission electron microscope. Here we present\nmeasurements on temperature and field dependence of magnetization and time\ndependence of thermoremanent magnetization. Our conclusion based on these\nmeasurements is that the system shows spin glass like behavior."
    },
    {
        "anchor": "Films of Bacteria at Interfaces (FBI): Remodeling of Fluid Interfaces by\n  Pseudomonas aeruginosa: Bacteria at fluid interfaces endure physical and chemical stresses unique to\nthese highly asymmetric environments. The responses of Pseudomonas aeruginosa\nPAO1 and PA14 to a hexadecane-water interface are compared. PAO1 cells form\nelastic films of bacteria, excreted polysaccharides and proteins, whereas PA14\ncells move actively without forming an elastic film. Studies of PAO1 mutants\nshow that, unlike solid-supported biofilms, elastic interfacial film formation\noccurs in the absence of flagella, pili, or certain polysaccharides. Highly\ninduced genes identified in transcriptional profiling include those for\nputative enzymes and a carbohydrate metabolism enzyme, alkB2; this latter gene\nis not upregulated in PA14 cells. Notably, PAO1 mutants lacking the alkB2 gene\nfail to form an elastic layer. Rather, they form an active film like that\nformed by PA14. These findings demonstrate that genetic expression is altered\nby interfacial confinement, and suggest that the ability to metabolize alkanes\nmay play a role in elastic film formation at oil-water interfaces.",
        "positive": "Comment on \"Experimental Evidence for a State-Point-Dependent\n  Density-Scaling Exponent of Liquid Dynamics\": Recently Sanz et al. [A. Sanz, T. Hecksher, H.W. Hansen, J.C. Dyre, K. Niss,\nand U.R. Pedersen, Phys. Rev. Lett. 122, 055501 (2019).] reported that the\nscaling exponent gamma for tetramethyl-tetraphenyl-trisiloxane (DC704) varied\nwith temperature; i.e., was not a material constant. Such a finding is at odds\nwith previously published results on this compound and on more than 100 other\nliquids and polymers. The result of Sanz et al. comes from their measurement of\na pressure dependence of the relaxation time at low temperature that becomes\nweaker with increasing pressure. Such a result is unphysical and contrary to\nthe behavior of all known liquids. We re-measured this pressure dependence for\nDC704 and find it to be linear over the studied range. Thus, the conclusion of\nSans et al. is incorrect; gamma for DC704 is state-point independent, in accord\nwith other simple liquids and polymers."
    },
    {
        "anchor": "Dynamics of supercooled liquids: density fluctuations and Mode Coupling\n  Theory: We write equations of motion for density variables that are equivalent to\nNewtons equations. We then propose a set of trial equations parameterised by\ntwo unknown functions to describe the exact equations. These are chosen to best\nfit the exact Newtonian equations. Following established ideas, we choose to\nseparate these trial functions into a set representing integrable motions of\ndensity waves, and a set containing all effects of non-integrability. It\ntranspires that the static structure factor is fixed by this minimum condition\nto be the solution of the Yvon-Born-Green (YBG) equation. The residual\ninteractions between density waves are explicitly isolated in their Newtonian\nrepresentation and expanded by choosing the dominant objects in the phase space\nof the system, that can be represented by a dissipative term with memory and a\nrandom noise. This provides a mapping between deterministic and stochastic\ndynamics. Imposing the Fluctuation-Dissipation Theorem (FDT) allows us to\ncalculate the memory kernel. We write exactly the expression for it, following\ntwo different routes, i.e. using explicitly Newtons equations, or instead,\ntheir implicit form, that must be projected onto density pairs, as in the\ndevelopment of the well-established Mode Coupling Theory (MCT). We compare\nthese two ways of proceeding, showing the necessity to enforce a new equation\nof constraint for the two schemes to be consistent. Thus, while in the first\n`Newtonian' representation a simple gaussian approximation for the random\nprocess leads easily to the Mean Spherical Approximation (MSA) for the statics\nand to MCT for the dynamics of the system, in the second case higher levels of\napproximation are required to have a fully consistent theory.",
        "positive": "Translational and reorientational dynamics in deep eutectic solvents: We performed rheological measurements of the typical deep eutectic solvents\n(DESs) glyceline, ethaline, and reline in a very broad temperature and dynamic\nrange, extending from the low-viscosity to the high-viscosity\nsupercooled-liquid regime. We find that the mechanical compliance spectra can\nbe well described by the random free-energy barrier hopping model, while the\ndielectric spectra on the same materials involve significant contributions\narising from reorientational dynamics. The temperature-dependent viscosity and\nstructural relaxation time, revealing non-Arrhenius behavior typical for glassy\nfreezing, are compared to the ionic dc conductivity and relaxation times\ndetermined by broadband dielectric spectroscopy. For glyceline and ethaline we\nfind essentially identical temperature dependences for all dynamic quantities.\nThese findings point to a close coupling of the ionic and molecular\ntranslational and reorientational motions in these systems. However, for reline\nthe ionic charge transport appears decoupled from the structural and\nreorientational dynamics, following a fractional Walden rule. Especially, at\nlow temperatures the ionic conductivity in this DES is enhanced by about one\ndecade compared to expectations based on the temperature dependence of the\nviscosity. The results for all three DESs can be understood without invoking a\nrevolving-door mechanism previously considered as a possible charge-transport\nmechanism in DESs."
    },
    {
        "anchor": "Training, Memory and Universal Scaling in Amorphous Frictional Granular\n  Matter: We report a joint experimental and theoretical investigation of cyclic\ntraining of amorphous frictional granular assemblies, with special attention to\nmemory formation and retention. Measures of dissipation and compactification\nare introduced, culminating with a proposed scaling law for the reducing\ndissipation and increasing memory. This scaling law is expected to be\nuniversal, insensitive to the details of the elastic and frictional\ninteractions between the granules.",
        "positive": "Percolation Phase Transition from Ionic Liquids to Ionic Liquid Crystals: As typical complex liquids, ionic liquids (ILs) exhibit phases beyond the\ndescription of simple liquid theories. In particular, with an intermediate\ncationic side-chain length, ILs can form the nanoscale segregated liquid (NSL)\nphase, which will eventually transform into the ionic liquid crystal (ILC)\nphase when the side chains are adequately long. However, the microscopic\nmechanism of this transformation is still unclear. In this work, by means of\ncoarse-grained molecular dynamics simulation, we show that, with increasing\ncationic side-chain length, some local pieces of non-polar domains are\ngradually formed by side chains aligned in parallel inside the NSL phase,\nbefore an abrupt percolation phase transition happens when the system\ntransforms into the ILC phase, manifesting that it is a critical phenomenon.\nPercolation phase transition is applied to ILs, providing new insights into\nmany recent observations both in experiments and simulations."
    },
    {
        "anchor": "On the power spectrum of undulations of simulated bilayers: The best finite Fourier Series for a smooth surface $h(x,y)$ closest to the\npositions of heads of amphiphiles in the least-square sense, agrees fully with\nthe Fourier coefficients obtained by a direct summation over raw data points.\nBoth metods produce structure factors $S(q)$ containing all necessary features:\nsmall-q divergence, a minimum, the raise to the ubiquitous nearest neighbor\npeak near $q=2\\pi/$(coll.diameter) and further peaks. The Laurent series is\nalso discussed.",
        "positive": "Rational design and dynamics of self-propelled colloidal bead chains:\n  from rotators to flagella: The quest for designing new self-propelled colloids is fuelled by the demand\nfor simple experimental models to study the collective behaviour of their more\ncomplex natural counterparts. Most synthetic self-propelled particles move by\nconverting the input energy into translational motion. In this work we address\nthe question if simple self-propelled spheres can assemble into more complex\nstructures that exhibit rotational motion, possibly coupled with translational\nmotion as in flagella. We exploit a combination of induced dipolar interactions\nand a bonding step to create permanent linear bead chains, composed of\nself-propelled Janus spheres, with a well-controlled internal structure. Next,\nwe study how flexibility between individual swimmers in a chain can affect its\nswimming behaviour. Permanent rigid chains showed only active rotational or\nspinning motion, whereas longer semi-flexible chains showed both translational\nand rotational motion resembling flagella like-motion, in the presence of the\nfuel. Moreover, we are able to reproduce our experimental results using\nnumerical calculations with a minimal model, which includes full hydrodynamic\ninteractions with the fluid. Our method is general and opens a new way to\ndesign novel self-propelled colloids with complex swimming behaviours, using\ndifferent complex starting building blocks in combination with the flexibility\nbetween them."
    },
    {
        "anchor": "Shape transitions in soft spheres regulated by elasticity: We study elasticity-driven morphological transitions of soft spherical core\nshell structures in which the core can be treated as an isotropic elastic\ncontinuum and the surface or shell as a tensionless liquid layer, whose elastic\nresponse is dominated by bending. To generate the transitions, we consider the\ncase where the surface area of the liquid layer is increased for a fixed amount\nof interior elastic material. We find that generically there is a critical\nexcess surface area at which the isotropic sphere becomes unstable to buckling.\nAt this point it adopts a lower symmetry wrinkled structure that can be\ndescribed by a spherical harmonic deformation. We study the dependence of the\nbuckled sphere and critical excess area of the transition on the elastic\nparameters and size of the system. We also relate our results to recent\nexperiments on the wrinkling of gel-filled vesicles as their interior volume is\nreduced. The theory may have broader applications to a variety of related\nstructures from the macroscopic to the microscopic, including the wrinkling of\ndried peas, raisins, as well as the cell nucleus.",
        "positive": "Localized Stress Fluctuations Drive Shear Thickening in Dense\n  Suspensions: The mechanical response of solid particles dispersed in a Newtonian fluid\nexhibits a wide range of nonlinear phenomena including a dramatic increase in\nthe viscosity \\cite{1-3} with increasing stress. If the volume fraction of the\nsolid phase is moderately high, the suspension will undergo continuous shear\nthickening (CST), where the suspension viscosity increases smoothly with\napplied shear stress; at still higher volume fractions the suspension can\ndisplay discontinuous shear thickening (DST), where the viscosity changes\nabruptly over several orders of magnitude upon increasing applied stress.\nProposed models to explain this phenomenon are based in two distinct types of\nparticle interactions, hydrodynamic\\cite{2,4,5} and frictional\\cite{6-10}. In\nboth cases, the increase in the bulk viscosity is attributed to some form of\nlocalized clustering\\cite{11,12}. However, the physical properties and\ndynamical behavior of these heterogeneities remains unclear. Here we show that\ncontinuous shear thickening originates from dynamic localized well defined\nregions of particles with a high viscosity that increases rapidly with\nconcentration. Furthermore, we find that the spatial extent of these regions is\nlargely determined by the distance between the shearing surfaces. Our results\ndemonstrate that continuous shear thickening arises from increasingly frequent\nlocalized discontinuous transitions between coexisting low and high viscosity\nNewtonian fluid phases. Our results provide a critical physical link between\nthe microscopic dynamical processes that determine particle interactions and\nbulk rheological response of shear thickened fluids."
    },
    {
        "anchor": "Monte Carlo study of the frame, fluctuation and internal tensions of\n  fluctuating membranes with fixed area: Three types of surface tensions can be defined for lipid membranes: the\ninternal tension, $\\sigma$, conjugated to the real membrane area in the\nHamiltonian, the mechanical frame tension, $\\tau$, conjugated to the projected\narea, and the \"fluctuation tension\", $r$, obtained from the fluctuation\nspectrum of the membrane height.\n  We investigate these surface tensions by means of a Monge gauge lattice Monte\nCarlo simulation involving the exact, nonlinear, Helfrich Hamiltonian and a\nmeasure correction for excess entropy of the Monge gauge. Our results for the\nrelation between $\\sigma$ and $\\tau$ agrees well with the theoretical\nprediction of [J.-B. Fournier and C. Barbetta, Phys. Rev. Lett., 2008, 100,\n078103] based on a Gaussian approximation. This provides a valuable knowledge\nof~$\\tau$ in the standard Gaussian models where the tension is controlled by\n$\\sigma$. However, contrary to the conjecture in the above paper, we find that\n$r$ exhibits no significant difference from $\\tau$ over more than five decades\nof tension. Our results appear to be valid in the thermodynamic limit and are\nrobust to changing the ensemble in which the membrane area is controlled.",
        "positive": "Molecular dynamics simulation for cross-linking processes and material\n  properties of epoxy resins with the first principle calculation combined with\n  global reaction route mapping algorithms: Herein, epoxy resin is cured by coupling quantum chemical (QC) calculations\nwith molecular dynamics (MD) simulations that enable parameter-free prediction\nof material characteristics. A polymer network is formed by the reaction\nbetween base resin and curing agent. The reaction uses activation energy and\nheat of formation data obtained by first-principle calculations coupled with\nglobal reaction route mapping (GRRM) algorithms. Density, glass transition\ntemperature, Young's modulus, and curing conversion is used to validate the\nprocedure. Experimental and simulation results indicate that base resin with\nmulti-functional reaction groups increases glass-transition temperature and\nYoung's modulus because of cross-linked formations at the molecular scale."
    },
    {
        "anchor": "The role of string-like, supramolecular assemblies in reentrant\n  supernematic liquid crystals: Using a combination of isothermal-isobaric Monte Carlo and microcanonical\nmolecular dynamics we investigate the relation between structure and\nself-diffusion in various phases of a model liquid crystal using the\nGay-Berne-Kihara potential. These molecules are confined to a mesoscopic\nslit-pore with atomically smooth substrate surfaces. As reported recently [see\nM. G. Mazza {\\em et al.}, Phys. Rev. Lett. {\\bf 105}, 227802 (2010)], a\nreentrant nematic (RN) phase may form at sufficiently high pressures/densities.\nThis phase is characterized by a high degree of nematic order and a\nsubstantially enhanced self-diffusivity in the direction of the director\n$\\hat{\\bm{n}}$ which exceeds that of the lower-density nematic and an\nintermittent smectic A phase by about an order of magnitude. Here we\ndemonstrate that the unique transport behavior in the RN phase may be linked to\na confinement-induced packing effect which causes the formation of\nsupramolecular, string-like conformations. The strings consist of several\nindividual molecules that are capable of travelling in the direction of\n$\\hat{\\bm{n}}$ as individual \"trains\" consisting of chains of molecular \"cars\".\nIndividual trains run in parallel and may pass each other at sufficiently high\npressures.",
        "positive": "The effects of curvature on the propagation of undulatory waves in lower\n  dimensional elastic materials: The mechanics of lower dimensional elastic structures depends strongly on the\ngeometry of their stress-free state. Elastic deformations separate into\nin-plane stretching and lower energy out-of-plane bending deformations. For\nelastic structures with a curved stress-free state, these two elastic modes are\ncoupled within linear elasticity. We investigate the effect of that\ncurvature-induced coupling on wave propagation in lower dimensional elastic\nstructures, focusing on the simplest example -- a curved elastic rod. We find\nthat the dispersion relation of the waves becomes gapped in the presence of\nfinite curvature; bending modes are absent below a frequency proportional to\nthe curvature of the rod. By studying the scattering of undulatory waves off\nregions of uniform curvature, we find that undulatory waves with frequencies in\nthe gap associated with the curved region tunnel through that curved region via\nconversion into compression waves. These results should be directly applicable\nto the spectrum and spatial distribution of phonon modes in a number of curved\nrod-like elastic solids, including carbon nanotubes and biopolymer filaments."
    },
    {
        "anchor": "Effects of Eye-phase in DNA unzipping: The onset of an \"eye-phase\" and its role during the DNA unzipping is studied\nwhen a force is applied to the interior of the chain. The directionality of the\nhydrogen bond introduced here shows oscillations in force-extension curve\nsimilar to a \"saw-tooth\" kind of oscillations seen in the protein unfolding\nexperiments. The effects of intermediates (hairpins) and stacking energies on\nthe melting profile have also been discussed.",
        "positive": "Capillary Interactions on Fluid Interfaces: Opportunities for Directed\n  Assembly: A particle placed in soft matter distorts its host and creates an energy\nlandscape. This can occur, for example, for particles in liquid crystals, for\nparticles on lipid bilayers or for particles trapped at fluid interfaces. Such\nenergies can be used to direct particles to assemble with remarkable degrees of\ncontrol over orientation and structure. These notes explore that concept for\ncapillary interactions, beginning with particle trapping at fluid interfaces,\naddressing pair interactions on planar interfaces and culminating with\ncurvature capillary migration. Particular care is given to the solution of the\nassociated boundary value problems to determine the energies of interaction.\nExperimental exploration of these interactions on planar and curved interfaces\nis described. Theory and experiment are compared. These interactions provide a\nrich toolkit for directed assembly of materials, and, owing to their close\nanalogy to related systems, pave the way to new explorations in materials\nscience."
    },
    {
        "anchor": "Temperature-dependent Pattern Formation in Drying Aqueous Droplets of\n  Lysozyme: Drying colloidal droplets have a wide range of applications from medical\ndiagnostics to coatings for industries. This paper explores the effects of the\nsubstrate temperature (ranging from $25$ to $55 ^{\\circ}$C) and various initial\nconcentrations ($\\phi$) of $1$ to $20$ wt% of lysozyme in an aqueous solution\non its drying and final dried film state using bright-field optical microscopy.\nThe $\\phi$ is divided into three regimes, ultra-concentrated ($20$ $<$ $\\phi$\n$\\leq$ $17$ wt%), concentrated ($17$ $<$ $\\phi$ $\\leq$ $9$ wt%) and diluted\n($9$ $<$ $\\phi$ $\\leq$ $1$ wt%). Increasing $\\phi$ in these regimes finds that\nthis movement in the later non-linear region slows down as the front carries\nand deposits protein molecules until the supply in solution is exhausted. In\nthe ultra-concentrated regime, the fluid front moves linearly throughout the\ndrying process. The deposition of protein onto the surface by the fluid front\ncreates the \"coffee-ring\" and increases with increasing $\\phi$. A dimple is\nobserved in a central mound-structure, which grows with increasing $\\phi$. As\nthe temperature increases the drying rate increases, reducing the time for\nconvective flow and the deposition of material at the fluid front.\nInterestingly, at (T, $\\phi$) = ($55 ^{\\circ}$C, $20$ wt%), the droplet forms\nthe thickest film with suppressed ring formation. The dimple diminishes in the\nultra-concentrated regime, whereas it changes to an expanded spot in some\nsamples of the diluted and concentrated regimes with elevated temperatures.\nBoth initial concentration and substrate temperature lead to surface tension\nand temperature gradients across the droplet, affecting the morphological\npatterns. This study provides insights into protein-protein and\nprotein-substrate interactions driven by temperature and concentration for\nbiomedical and biosensing applications.",
        "positive": "Generalized Onsager theory for strongly anisometric patchy colloids: The implications of soft `patchy' interactions on the orientational\ndisorder-order transition of strongly elongated colloidal rods and flat disks\nis studied within a simple Onsager-van der Waals density functional theory. The\ntheory provides a generic framework for studying the liquid crystal phase\nbehaviour of highly anisometric cylindrical colloids, which carry a distinct\ngeometrical pattern of repulsive or attractive soft interactions localised on\nthe particle surface. In this paper, we apply our theory to the case of charged\nrods and disks for which the local electrostatic interactions can be described\nby a screened-Coulomb potential. We consider infinitely thin rod-like cylinders\nwith a uniform line charge and infinitely thin discotic cylinders with several\ndistinctly different surface charge patterns. Irrespective of the backbone\nshape, the isotropic-nematic phase diagrams of charged colloids feature a\ngeneric destabilization of nematic order, a dramatic narrowing of the biphasic\ndensity region and a reentrant phenomenon upon reducing the electrostatic\nscreening. At higher particle density the electrostatic repulsion leads to a\ncomplete suppression of nematic order in favour of spatially inhomogeneous\nliquid crystals."
    },
    {
        "anchor": "Kinetics of Phase Separation in Thin Films: Simulations for the\n  Diffusive Case: We study the diffusion-driven kinetics of phase separation of a symmetric\nbinary mixture (AB), confined in a thin-film geometry between two parallel\nwalls. We consider cases where (a) both walls preferentially attract the same\ncomponent (A), and (b) one wall attracts A and the other wall attracts B (with\nthe same strength). We focus on the interplay of phase separation and wetting\nat the walls, which is referred to as {\\it surface-directed spinodal\ndecomposition} (SDSD). The formation of SDSD waves at the two surfaces, with\nwave-vectors oriented perpendicular to them, often results in a metastable\nlayered state (also referred to as ``stratified morphology''). This state is\nreminiscent of the situation where the thin film is still in the one-phase\nregion but the surfaces are completely wet, and hence coated with thick wetting\nlayers. This metastable state decays by spinodal fluctuations and crosses over\nto an asymptotic growth regime characterized by the lateral coarsening of\npancake-like domains. These pancakes may or may not be coated by precursors of\nwetting layers. We use Langevin simulations to study this crossover and the\ngrowth kinetics in the asymptotic coarsening regime.",
        "positive": "Statistical Mechanical theory for spatio-temporal evolution of\n  Intra-tumor heterogeneity in cancers: Analysis of Multiregion sequencing data: Heterogeneity in characteristics from one region (sub-population) to another,\ncommonly observed in complex systems, such as glasses and a collection of\ncells, is hard to describe theoretically. In the context of cancer, intra-tumor\nheterogeneity (ITH), characterized by cells with genetic and phenotypic\nvariability that co-exist within a single tumor, is often the cause of\nineffective therapy and recurrence of cancer. Multi-region sequencing (M-Seq),\nobtained by sampling multiple regions of a single tumor, has vividly\ndemonstrated the pervasive nature of ITH, raising the need for a theory that\naccounts for evolution of tumor heterogeneity. Here, we develop a statistical\nmechanical theory to quantify ITH, using the Hamming distance, between genetic\nmutations in distinct regions within a single tumor. An analytic expression for\nITH, expressed in terms of cell division probability ($\\alpha$) and mutation\nprobability ($p$), is validated using cellular-automaton type simulations.\nApplication of the theory successfully captures ITH extracted from M-seq data\nin patients with exogenous cancers (melanoma and lung). The theory, based on\npunctuated evolution at the early stages of the tumor followed by neutral\nevolution, is accurate provided the spatial variation in the tumor mutation\nburden is not large. We show that there are substantial variations in ITH in\ndistinct regions of a single solid tumor, which supports the notion that\ndistinct subclones could co-exist. The simulations show that there are\nsubstantial variations in the sub-populations, with the ITH increasing as the\ndistance between the regions increases. The analytical and simulation framework\ndeveloped here could be used in the quantitative analyses of the experimental\n(M-Seq) data. More broadly, our theory is likely to be useful in analyzing\ndynamic heterogeneity in complex systems such as super-cooled liquids."
    },
    {
        "anchor": "Two-body entropy of two-dimensional fluids: The two-body (pair) contribution to the entropy of two-dimensional Yukawa\nsystems is calculated and analyzed. It is demonstrated that in the vicinity of\nthe fluid-solid (freezing) phase transition the pair entropy exhibits an abrupt\njump in a narrow temperature range and this can be used to identify the\nfreezing point. Relations to the full excess entropy and some existing freezing\nindicators are briefly discussed.",
        "positive": "Anomalous transport in the soft-sphere Lorentz model: The sensitivity of anomalous transport in crowded media to the form of the\ninter-particle interactions is investigated through computer simulations. We\nextend the highly simplified Lorentz model towards realistic natural systems by\nmodeling the interactions between the tracer and the obstacles with a smooth\npotential. We find that the anomalous transport at the critical point happens\nto be governed by the same universal exponent as for hard exclusion\ninteractions, although the mechanism of how narrow channels are probed is\nrather different. The scaling behavior of simulations close to the critical\npoint confirm this exponent. Our result indicates that the simple Lorentz model\nmay be applicable to describing the fundamental properties of long-range\ntransport in real crowded environments."
    },
    {
        "anchor": "Generating moment equations in the Doi model of liquid-crystalline\n  polymers: We present a self-consistent method for deriving moment equations for kinetic\nmodels of polymer dynamics. The Doi model [M. Doi, J.Polymer. Sci., Polym.\nPhys. Ed. 19, 229 (1981)] of liquid-crystalline polymers with the Onsager\nexcluded-volume potential is considered as an example. To lowest order, this\nmethod amounts to a simple effective potential different from the Maier-Saupe\nform. Analytical results are presented which indicate that this effective\npotential provides a better approximation to the Onsager potential than the\nMaier-Saupe potential. Corrections to the effective potential are obtained.",
        "positive": "Shear viscosity of two-state enzyme solutions: We discuss the shear viscosity of a Newtonian solution of catalytic enzymes\nand substrate molecules. The enzyme is modeled as a two-state dimer consisting\nof two spherical domains connected with an elastic spring. The enzymatic\nconformational dynamics is induced by the substrate binding and such a process\nis represented by an additional elastic spring. Employing the Boltzmann\ndistribution weighted by the waiting times of enzymatic species in each\ncatalytic cycle, we obtain the shear viscosity of dilute enzyme solutions as a\nfunction of substrate concentration and its physical properties. The substrate\naffinity distinguishes between fast and slow enzymes, and the corresponding\nviscosity expressions are obtained. Furthermore, we connect the obtained\nviscosity with the diffusion coefficient of a tracer particle in enzyme\nsolutions."
    },
    {
        "anchor": "Motility-induced coexistence of a hot liquid and a cold gas: If two phases exist at the same time, such as a gas and a liquid, they have\nthe same temperature. This fundamental law of equilibrium physics is known to\napply even to many non-equilibrium systems. However, recently, there has been\nmuch attention in the finding that inertial self-propelled particles like Janus\ncolloids in a plasma or microflyers could self-organize into a hot gas-like\nphase that coexists with a colder liquid-like phase. Here, we show that a\nkinetic temperature difference across coexisting phases can occur even in\nequilibrium systems when adding generic (overdamped) self-propelled particles.\nIn particular, we consider mixtures of overdamped active and inertial passive\nBrownian particles and show that when they phase separate into a dense and a\ndilute phase, both phases have different kinetic temperatures. Surprisingly, we\nfind that the dense phase (liquid) cannot only be colder but also hotter than\nthe dilute phase (gas). This effect hinges on correlated motions where active\nparticles collectively push and heat up passive ones primarily within the dense\nphase. Our results answer the fundamental question if a non-equilibrium gas can\nbe colder than a coexisting liquid and create a route to equip matter with\nself-organized domains of different kinetic temperatures.",
        "positive": "Logarithmic aging via instability cascades in disordered systems: Many complex and disordered systems fail to reach equilibrium after they have\nbeen quenched or perturbed. Instead, they sluggishly relax toward equilibrium\nat an ever-slowing, history-dependent rate, a process termed physical aging.\nThe microscopic processes underlying the dynamic slow-down during aging and the\nreason for its similar occurrence in different systems remain poorly\nunderstood. Here, we reveal the structural mechanism underlying logarithmic\naging in disordered mechanical systems, through experiments in crumpled sheets\nand simulations of a disordered network of bi-stable elastic elements. We show\nthat under load, the system self-organizes to a metastable state poised on the\nverge of an instability, where it can remain for long, but finite times. The\nsystem's relaxation is intermittent, advancing via rapid sequences of\ninstabilities, grouped into self-similar, aging avalanches. Crucially, the\nquiescent dwell times between avalanches grow in proportion to the system's\nage, due to a slow increase of the lowest effective energy barrier, which leads\nto logarithmic aging."
    },
    {
        "anchor": "Single-molecule stretching experiments of flexible (wormlike) chain\n  molecules in different ensembles: Theory and a potential application of\n  finite chain length effects to nick-counting in DNA: We propose a formalism for deriving force-elongation and elongation-force\nrelations for flexible chain molecules from analytical expressions for their\nradial distribution function, which provides insight into the factors\ncontrolling the asymptotic behavior and finite chain length corrections. In\nparticular, we apply this formalism to our previously developed interpolation\nformula for the wormlike chain end-to-end distance distribution. The resulting\nexpression for the asymptotic limit of infinite chain length is of similar\nquality as the numerical evaluation of Marko's and Siggia's variational theory\nand considerably more precise than their interpolation formula. A comparison to\nnumerical data suggests, that our analytical expressions for the finite-chain\nlength corrections are of similar quality. As an application of our results we\ndiscuss the possibility of inferring the changing number of nicks in a\ndouble-stranded DNA molecule in single-molecule stretching experiments from the\naccompanying changes in the effective chain length.",
        "positive": "Equilibrium Statistics of Weakly Slip-Linked Gaussian Polymer Chains: We calculate the free energy and the pressure of a weakly slip-linked\nGaussian polymer chains. We show that the equilibrium statistics of a\nslip-linked system is different from one of the corresponding ideal chain\nsystem without any constraints by slip-links. It is shown that the pressure of\na slip-linked system decreases compared with the ideal system, which implies\nthat slip-linked chains spontaneously form aggregated cluster like compact\nstructures. These are qualitatively consistent with previous theoretical\nanalyses or multi chain simulations. We also show that repulsive potentials\nbetween chains, which have been phenomenologically utilized in simulations, can\ncancel the artificial pressure decrease."
    },
    {
        "anchor": "Scale competition in nonlinear Schrodinger models: Three types of nonlinear Schrodinger models with multiple length scales are\nconsidered. It is shown that the length-scale competition universally results\ninto arising of new localized stationary states. Multistability phenomena with\na controlled switching between stable states become possible.",
        "positive": "Athermal analogue of sheared dense Brownian suspensions: The rheology of dense Brownian suspensions of hard spheres is investigated\nnumerically beyond the low shear rate Newtonian regime. We analyze an athermal\nanalogue of these suspensions, with an effective logarithmic repulsive\npotential representing the vibrational entropic forces. We show that both\nsystems present the same rheology without adjustable parameters. Moreover, all\nrheological responses display similar Herschel-Bulkley relations once the shear\nstress and the shear rate are respectively rescaled by a characteristic stress\nscale and by a microscopic reorganization time-scale, both related to the\nnormal confining pressure. This pressure-controlled approach, originally\ndeveloped for granular flows, reveals a striking physical analogy between the\ncolloidal glass transition and granular jamming."
    },
    {
        "anchor": "Slip effects in polymer thin films: Probing the fluid dynamics of thin films is an excellent tool to study the\nsolid/liquid boundary condition. There is no need for external stimulation or\npumping of the liquid due to the fact that the dewetting process, an internal\nmechanism, acts as a driving force for liquid flow. Viscous dissipation within\nthe liquid and slippage balance interfacial forces. Thereby, friction at the\nsolid/liquid interface plays a key role towards the flow dynamics of the\nliquid. Probing the temporal and spatial evolution of growing holes or\nretracting straight fronts gives, in combination with theoretical models,\ninformation of the liquid flow field and especially the boundary condition at\nthe interface. We review the basic models and experimental results obtained\nduring the last years with exclusive regard to polymers as ideal model liquids\nfor fluid flow. Moreover, concepts that aim on explaining slippage on the\nmolecular scale are summarized and discussed.",
        "positive": "Glass transitions and dynamics in thin polymer films: dielectric\n  relaxation of thin films of polystyrene: The glass transition temperature $T_{\\rm g}$ and the temperature $T_{\\alpha}$\ncorresponding to the peak in the dielectric loss due to the $\\alpha$-process\nhave been simultaneously determined as functions of film thickness d through\ndielectric measurements for polystyrene thin films supported on glass\nsubstrate. The dielectric loss peaks have also been investigated as functions\nof frequency for a given temperature. A decrease in $T_{\\rm g}$ was observed\nwith decreasing film thickness, while $T_{\\alpha}$ was found to remain almost\nconstant for $d>d_{\\rm c}$ and to decrease drastically with decreasing d for\n$d<d_{\\rm c}$. Here, $d_{\\rm c}$ is a critical thickness dependent on molecular\nweight. The relaxation time of the $\\alpha$-process was found to have a d\ndependence similar to that of $T_{\\alpha}$. The relaxation function for the\n$\\alpha$-process was obtained by using the observed frequency dependence of the\npeak profile of the dielectric loss. The exponent $\\beta_{{\\tiny KWW}}$, which\nwas obtained from the relaxation functions, decreases as thickness decreases.\nThis suggests that the distribution of relaxation times for the\n$\\alpha$-process broadens with decreasing thickness. The thickness dependence\nof $T_{\\rm g}$ is directly related to the distribution of relaxation times for\nthe $\\alpha$-process, not to the relaxation time itself."
    },
    {
        "anchor": "Flocking of Active Particles in a Turbulent Flow: We investigate the effect of cooperative interactions in an ensemble of\nmicroorganisms, modelled as self-propelled disk-like and rod-like particles, in\na three-dimensional turbulent flow to show flocking as an emergent phenomenon.\nBuilding on the work by Choudhary, et al. [Europhys. Lett. 112, 24005 (2015)]\nfor two-dimensional systems, and combining ideas from active matter and\nturbulent transport, we show that non-trivial correlations between the flow and\nindividual dynamics are essential for the microorganisms to flock in, for\nexample, a turbulent three-dimensional, marine environment. Our results may\nhave implications especially in the modelling of artificial microswimmers in a\nhostile environment.",
        "positive": "Glassy Dynamics of Brownian Particles with Velocity-Dependent Friction: We consider a two-dimensional model system of Brownian particles in which\nslow particles are accelerated while fast particles are damped. The motion of\nthe individual particles are described by a Langevin equation with\nRayleigh-Helmholtz velocity dependent friction. In case of noninteracting\nparticles, the time evolution equations lead to a non-Gaussian velocity\ndistribution. The velocity dependent friction allows negative values of the\nfriction or energy intakes by slow particles which we consider as active\nmotion, and also causes breaking of the fluctuation dissipation relation.\nDefining the effective temperature proportional to the second moment of\nvelocity, it is shown that for a constant effective temperature the higher the\nnoise strength, the lower are the number of active particles in the system.\nUsing the Mori-Zwanzig formalism and the mode-coupling approximation, the\nequation of motion for the density auto-correlation function are derived. The\nequations are solved using the equilibrium structure factors. The\nintegration-through-transients approach is used to derive a relation between\nthe structure factor in the stationary state considering the interacting\nforces, and the conventional equilibrium static structure factor."
    },
    {
        "anchor": "Quantitative analysis of chain packing in polymer melts using large\n  scale molecular dynamics simulations: We have carried out a quantitative analysis of the chain packing in polymeric\nmelts using molecular dynamics simulations. The analysis involves constructing\nVoronoi tessellations in the equilibrated configurations of the polymeric\nmelts. In this work, we focus on the effects of temperature and polymer\nbackbone rigidity on the packing. We found that the Voronoi polyhedra near the\nchain ends are of higher volumes than those constructed around the other sites\nalong the backbone. Furthermore, we demonstrated that the backbone rigidity\n(tuned by fixing the bond angles) affect the Voronoi cell distribution in a\nsignificant manner, especially at lower temperatures. For the melts consisting\nof chains with fixed bond angles, the Voronoi cell distribution was found to be\nwider than that for the freely jointed chains without any angular restrictions.\nAs the temperature is increased, the effect of backbone rigidity on the Voronoi\ncell distributions diminishes and becomes similar to that of the freely jointed\nchains. Demonstrated dependencies of the distribution of the Voronoi cell\nvolumes on the nature of the polymers are argued to be important for\nefficiently designing the polymeric materials for various energy applications.",
        "positive": "Inflationary routes to Gaussian curved topography: Gaussian-curved shapes are obtained by inflating initially flat systems made\nof two superimposed strong and light thermoplastic impregnated fabric sheets\nheat-sealed together along a specific network of lines. The resulting inflated\nstructures are light and very strong because they (largely) resist deformation\nby the intercession of stretch. Programmed patterns of channels vary either\ndiscretely through boundaries, or continuously. The former give rise to\nfacetted structures that are in effect non-isometric origami and which cannot\nunfold as in conventional folded structures, since they present localized angle\ndeficit or surplus. Continuous variation of channel direction in the form of\nspirals is examined, giving rise to curved shells. We solve the inverse problem\nconsisting in finding a network of seam lines leading to a target axisymmetric\nshape on inflation. They too have strength from the metric changes that have\nbeen pneumatically driven, resistance to change being met with stretch and\nhence high forces like typical shells ."
    },
    {
        "anchor": "Dielectric microscopy with submillimeter resolution: In analogy with optical near-field scanning methods, we use tapered\ndielectric waveguides as probes for a millimeter wave vector network analyzer.\nBy scanning thin samples between two such probes we are able to map the\nspatially varying dielectric properties of materials with sub-wavelength\nresolution; using a 150 GHz probe in transmision mode we see spatial resolution\nof around 500 microns. We have applied this method to a variety of highly\nheterogeneous materials. Here we show dielectric maps of granite and oil shale.",
        "positive": "Dynamic phase transition induced by active molecules simulating a\n  facilitation mechanism in a supercooled liquid: The purpose of this work is to use active particles to study the effect of\nfacilitation on supercooled liquids. To this end we investigate the behavior of\na model supercooled liquid doped with intermittently active and intermittently\nslowed particles. To simulate a facilitation mechanism, the active particles\nare submitted intermittently to a force following the mobility of the most\nmobile molecule around, while the slowed particles are submitted to a friction\nforce. We observe upon activation, a fluidization of the whole medium\nsimultaneously to a large increase of the dynamic heterogeneity. This effect is\nreminiscent of the fluidization observed with molecular motors doping of the\nmedium. When the mobility characteristic time used in the facilitation\nmechanism matches the physical time characterizing the spontaneous mobility\naggregation of the material, we observe a phase transition associated with a\nstructural aggregation of active molecules. This transition is accompanied by a\nsharp increase of the fluidization and dynamic heterogeneity."
    },
    {
        "anchor": "Granular dynamics in compaction and stress relaxation: Elastic and dissipative properties of granular assemblies under uniaxial\ncompression are studied both experimentally and by numerical simulations.\nFollowing a novel compaction procedure at varying oscillatory pressures, the\nstress response to a step-strain reveals an exponential relaxation followed by\na slow logarithmic decay. Simulations indicate that the latter arises from the\ncoupling between damping and collective grain motion predominantly through\nsliding. We characterize an analogous \"glass transition\" for packed grains,\nbelow which the system shows aging in time-dependent sliding correlation\nfunctions.",
        "positive": "Stress response and structural transitions in sheared gyroidal and\n  lamellar amphiphilic mesophases: lattice-Boltzmann simulations: We report on the stress response of gyroidal and lamellar amphiphilic\nmesophases to steady shear simulated using a bottom-up lattice-Boltzmann model\nfor amphiphilic fluids and sliding periodic (Lees-Edwards) boundary conditions.\nWe study the gyroid per se (above the sponge-gyroid transition, of high\ncrystallinity) and the molten gyroid (within such a transition, of\nshorter-range order). We find that both mesophases exhibit shear-thinning, more\npronounced and at lower strain rates for the molten gyroid. At late times after\nthe onset of shear, the skeleton of the crystalline gyroid becomes a structure\nof interconnected irregular tubes and toroidal rings, mostly oriented along the\nvelocity ramp imposed by the shear, in contradistinction with free-energy\nLangevin-diffusion studies which yield a much simpler structure of disentangled\ntubes. We also compare the shear stress and deformation of lamellar mesophases\nwith and without amphiphile when subjected to the same shear flow applied\nnormal to the lamellae. We find that the presence of amphiphile allows (a) the\nshear stress at late times to be higher than in the case without amphiphile,\nand (b) the formation of rich patterns on the sheared interface, characterised\nby alternating regions of high and low curvature."
    },
    {
        "anchor": "Microrheological Studies of Regenerated Silk Fibroin Solution by Video\n  Microscopy: We have carried out studies on the rheological properties of regenerated silk\nfibroin (RSF) solution using video microscopy. The degummed silk from the\nBombyx mori silkworm was used to prepare RSF solution by dissolving it in\ncalcium nitrate tetrahydrate-methanol solvent. Measurements were carried out by\ntracking the position of an embedded micron-sized polystyrene bead within the\nRSF solution through video imaging. The time dependent mean squared\ndisplacement (MSD) of the bead in solution and hence, the complex shear modulus\nof this solution was calculated from the bead's position information. An\noptical tweezer was used to transport and locate the bead at any desired site\nwithin the micro-volume of the sample, to facilitate the subsequent free-bead\nvideo analysis. We present here the results of rheological measurements of the\nsilk polymer network in solution over a frequency range, whose upper limit is\nthe frame capture rate of our camera, at full resolution. By examining the\ndistribution of MSD of beads at different locations within the sample volume,\nwe demonstrate that this probe technique enables us to detect local\ninhomogeneties at micrometer length scales, not detectable either by a\nrheometer or from diffusing wave spectroscopy.",
        "positive": "Isomorph invariance in the liquid and plastic-crystal phases of\n  asymmetric-dumbbell models: We present a numerical study of the asymmetric dumbbell model consisting of\n``molecules'' constructed as two different-sized Lennard-Jones spheres\nconnected by a rigid bond. In terms of the largest (A) particle radius, we\nreport data for the structure and dynamics of the liquid phase for the bond\nlengths 0.05, 0.1, 0.2, and 0.5, and analogous data for the plastic-crystal\nphase for the bond lengths 0.05, 0.1, 0.2, and 0.3. Structure is probed by\nmeans of the AA, AB, and BB radial distribution functions. Dynamics is probed\nvia the A and B particle mean-square displacement as functions of time and via\nthe rotational time-autocorrelation function. Consistent with the systems'\nstrong virial potential-energy correlations, the structure and dynamics are\nfound to be isomorph invariant to a good approximation in reduced units, while\nthey generally vary considerably along isotherms of the same (20%) density\nvariation. Even the rotational time-autocorrelation function, which due to the\nconstant bond length is not predicted to be isomorph invariant, varies more\nalong isotherms than along isomorphs. Our findings provide the first validation\nof isomorph-theory predictions for plastic crystals for which isomorph\ninvariance, in fact, is found to apply better than in the liquid phase of\nasymmetric-dumbbell models."
    },
    {
        "anchor": "Unique Dynamic Correlation Length in Supercooled Liquids: We present a direct comparison of the number of dynamically correlated\nmolecules in the shear-mechanical and dielectric relaxations of the following\nseven supercooled organic liquids: triphenylethylene,\ntetramethyl-tetraphenyl-trisiloxane, polyphenyl ether, perhydrosqualene,\npolybutadiene, decahydroisoquinoline, and tripropylene glycol. For each liquid\nwe observe that the numbers of dynamically correlated molecules in the shear\nand in the dielectric relaxation are proportional. We show that this\nproportionality can be explained by the constancy of the decoupling index of\nthe shear and dielectric relaxation times in conjunction with time-temperature\nsuperposition. Moreover the value of this proportionality constant is related\nto the difference in stretching of the shear and dielectric response functions.\nThe most significant deviations from unity of this constant are found in a\nliquid with strong hydrogen bonds and in a polymer.",
        "positive": "Anomalous diffusion in viscoelastic media with active force dipoles: With the use of the \"two-fluid model\", we discuss anomalous diffusion induced\nby active force dipoles in viscoelastic media. Active force dipoles, such as\nproteins and bacteria, generate non-thermal fluctuating flows that lead to a\nsubstantial increment of the diffusion. Using the partial Green's function of\nthe two-fluid model, we first obtain passive (thermal) two-point correlation\nfunctions such as the displacement cross-correlation function between the two\npoint particles separated by a finite distance. We then calculate active\n(non-thermal) one-point and two-point correlation functions due to active force\ndipoles. The time correlation of a force dipole is assumed to decay\nexponentially with a characteristic time scale. We show that the active\ncomponent of the displacement cross-correlation function exhibits various\ncrossovers from super-diffusive to sub-diffusive behaviors depending on the\ncharacteristic time scales and the particle separation. Our theoretical results\nare intimately related to the microrheology technique to detect fluctuations in\nnon-equilibrium environment."
    },
    {
        "anchor": "Phase transition in peristaltic transport of frictionless granular\n  particles: Flow of dissipative particles driven by peristaltic motion of a tube is\nnumerically studied. A transition from slow unjammed flow to fast jammed flow\nis found through the observation of the mass flux if the minimum width of the\nperistaltic tube is smaller than a critical value. It is also found that\naverage and fluctuation of the transition time, and the peak value of the\nsecond moment of the mass flux exhibit power-law divergences at the critical\npoint and these variables satisfy scaling relationships near the critical\npoint. Dependences of the critical width and exponents on peristaltic velocity\nand on density are also discussed.",
        "positive": "A study of the size dependence of self diffusivity across the\n  solid-liquid transition: The present study investigates the effect of temperature-induced change of\nphase from face centred cubic solid to liquid on the size dependence of self\ndiffusivity of solutes through detailed molecular dynamics simulations on\nbinary mixtures consisting of a larger solvent and a smaller solute interacting\nvia Lennard-Jones potential. The effect of change in density during the\nsolid-liquid transition as well as in the solid and the liquid phase itself\nhave been studied through two sets of simulations one at fixed density(NVE)and\nanother at variable density(NPT). A size dependent diffusivity maximum is seen\nin both solid and liquid phases at most densities except at low liquid\ndensities. Two distinct regimes may be identified : linear and anomalous\nregimes. It is seen that the effect of solid to liquid transition is to shift\nthe diffusivity maximum to smaller sizes of the solutes and decrease the height\nof the maximum. This is attributed to the predominant influence of disorder and\nrelatively weaker influence of density. The latter shifts the diffusivity\nmaximum towards larger solute size while the former does exactly the opposite.\nInterestingly, we find that lower densities lead to weaker diffusivity maximum.\nWe report for the first time for systems with large solute-solvent interaction\nstrength, $\\epsilon_{uv}$, multiple diffusivity maximum is seen as a function\nof the solute size. The origin of this is not clear. A remarkable difference in\nthe ballistic-diffusive transition is seen between solutes from the linear\nregime and anomalous regime. It is found that this transition is sharp for\nsolutes from anomalous regime. This provides interesting insight into motion of\nanomalous regime solutes. Apart from these, we report several properties which\nare different for the linear and anomalous regime solutes."
    },
    {
        "anchor": "Strong confinement of active microalgae leads to inversion of vortex\n  flow and enhanced mixing: Microorganisms swimming through viscous fluids imprint their propulsion\nmechanisms in the flow fields they generate. Extreme confinement of these\nswimmers between rigid boundaries often arises in natural and technological\ncontexts, yet measurements of their mechanics in this regime are absent. Here,\nwe show that strongly confining the microalga Chlamydomonas between two\nparallel plates not only inhibits its motility through contact friction with\nthe walls but also leads, for purely mechanical reasons, to inversion of the\nsurrounding vortex flows. Insights from the experiment lead to a simplified\ntheoretical description of flow fields based on a quasi-2D Brinkman\napproximation to the Stokes equation rather than the usual method of images. We\nargue that this vortex flow inversion provides the advantage of enhanced fluid\nmixing despite higher friction. Overall, our results offer a comprehensive\nframework for analyzing the collective flows of strongly confined swimmers.",
        "positive": "Coupling between bulk- and surface chemistry in suspensions of charged\n  colloids: The ionic composition and pair correlations in fluid phases of realistically\nsalt-free charged colloidal sphere suspensions are calculated in the primitive\nmodel. We obtain the number densities of all ionic species in suspension,\nincluding low-molecular weight microions, and colloidal macroions with acidic\nsurface groups, from a self-consistent solution of a coupled physicochemical\nset of nonlinear algebraic equations and non-mean-field liquid integral\nequations. Here, we study suspensions of colloidal spheres with sulfonate or\nsilanol surface groups, suspended in demineralized water that is saturated with\ncarbon dioxide under standard atmosphere. The only input required for our\ntheoretical scheme are the acidic dissociation constants pKa, and effective\nsphere diameters of all involved ions. Our method allows for an ab initio\ncalculation of colloidal bare and effective charges, at high numerical\nefficiency."
    },
    {
        "anchor": "Study of unzipping transitions in an adsorbed polymer by a periodic\n  force: Using Monte Carlo simulations, we study the dynamic transitions in the\nunzipping of an adsorbed homogeneous polymer on a surface (or wall). We\nconsider three different types of surfaces. One end of the polymer is always\nkept anchored, and other end monomer is subjected to a periodic force with\nfrequency $\\omega$ and amplitude $g_0$. We observe that the force-distance\nisotherms show hysteresis loops in all the three cases. For all the three\ncases, it is found that the area of the hysteresis loop, $A_{loop}$, scales as\n$1/\\omega$ in the higher frequency regime, and as $g_0^{\\alpha} \\omega^{\\beta}$\nwith exponents $\\alpha = 1$ and $\\beta = 1.25$ in the lower frequency regime.\nThe values of exponents $\\alpha$ and $\\beta$ are similar to the exponents\nobtained in the earlier Monte Carlo simulation studies of DNA chains and a\nLangevin dynamics simulation study of longer DNA chains.",
        "positive": "Flow network controlled shape transformation of a thin membrane through\n  differential fluid storage and surface expansion: The mechanical properties of a thin, planar material, perfused by an embedded\nflow network, can be changed locally and globally by the fluid transport and\nstorage, resulting in small or large-scale deformation, such as out-of-plane\nbuckling. Fluid absorption and storage eventually cause the material to locally\nswell. Different parts can hydrate and swell unevenly, prompting a differential\nexpansion of the surface. In order to computationally study the hydraulically\ninduced differential swelling and buckling of such a membrane, we develop a\nnetwork model that describes both the membrane shape and fluid movement,\ncoupling mechanics with hydrodynamics. We simulate the time-dependent fluid\ndistribution in the flow network based on a spatially explicit resistor network\nmodel with local fluid-storage capacitance. The shape of the surface is modeled\nby a spring network produced by a tethered mesh discretization, in which local\nbond rest lengths are adjusted instantaneously according to associated local\nfluid content in the capacitors in a quasi-static way. We investigate the\neffects of various designs of the flow network, including overall hydraulic\ntraits (resistance and capacitance) and hierarchical architecture (arrangement\nof major and minor veins), on the specific dynamics of membrane shape\ntransformation. To quantify these effects, we explore the correlation between\nlocal Gaussian curvature and relative stored fluid content in each hierarchy by\nusing linear regression, which reveals that stronger correlations could be\ninduced by less densely connected major veins. This flow-controlled mechanism\nof shape transformation was inspired by the blooming of flowers through the\nunfolding of petals. It can potentially offer insights for other reversible\nmotions observed in plants induced by differential turgor and water transport\nthrough the xylem vessels, as well as engineering applications."
    },
    {
        "anchor": "Liquid-state polaron theory of the hydrated electron revisited: The quantum path integral/classical liquid-state theory of Chandler and\nco-workers, created to describe an excess electron in solvent, is re-examined\nfor the hydrated electron. The portion that models electron-water density\ncorrelations is replaced by two equations: the range optimized random phase\napproximation (RO-RPA), and the DRL approximation to the \"two-chain\" equation,\nboth shown previously to describe accurately the static structure and\nthermodynamics of strongly charged polyelectrolyte solutions. The static\nequilibrium properties of the hydrated electron are analyzed using five\ndifferent electron-water pseudopotentials. The theory is then compared with\ndata from mixed quantum/classical Monte Carlo and molecular dynamics\nsimulations using these same pseudopotentials. It is found that the predictions\nof the RO-RPA and DRL-based polaron theories are similar and improve upon\nprevious theory, with values for almost all properties analyzed in reasonable\nquantitative agreement with the available simulation data. Also, it is found\nusing the Larsen, Glover and Schwartz pseudopotential that the theories give\nvalues for the solvation free energy that are at least three times larger than\nthat from experiment.",
        "positive": "Reorganization energy of electron transfer at the solvent glass\n  transition: We present a molecular-dynamics study of the solvent reorganization energy of\nelectron transfer in supercooled water. We observe a sharp decrease of the\nreorganization energy at a temperature identified as the temperature of\nstructural arrest due to cage effect as discussed by the mode coupling theory.\nBoth the heat capacity and dielectric susceptibility of the pure water show\nsharp drops at about the same temperature. This temperature also marks the\nonset of the enhancement of translational diffusion relative to rotational\nrelaxation signaling the break-down of the Stokes-Einstein relation. The change\nin the reorganization energy at the transition temperature reflects the\ndynamical arrest of the slow, collective relaxation of the solvent related to\nDebye relaxation of the solvent dipolar polarization."
    },
    {
        "anchor": "Waves on an interface between two phase-separated Bose-Einstein\n  condensates: We examine waves localized near a boundary between two weakly segregated\nBose-Einstein condensates. In the case of a wavelength of order of or larger\nthan the thickness of the overlap region the variational method is used. The\ndispersion laws for the two oscillation branches are found in analytic form.\nThe opposite case of a wavelength much shorter than the healing length in the\nbulk condensate is also discussed.",
        "positive": "Self-diffusion of Rod-like Viruses Through Smectic Layer: We report the direct visualization at the scale of single particles of mass\ntransport between smectic layers, also called permeation, in a suspension of\nrod-like viruses. Self-diffusion takes place preferentially in the direction\nnormal to the smectic layers, and occurs by quasi-quantized steps of one rod\nlength. The diffusion rate corresponds with the rate calculated from the\ndiffusion in the nematic state with a lamellar periodic ordering potential that\nis obtained experimentally."
    },
    {
        "anchor": "Fine Structure of Viral dsDNA Encapsidation: In vivo configurations of dsDNA of bacteriophage viruses in a capsid are\nknown to form hexagonal chromonic liquid crystal phases. This article studies\nthe liquid crystal ordering of viral dsDNA in an icosahedral capsid, combining\nthe chromonic model with that of liquid crystals with variable degree of\norientation. The scalar order parameter of the latter allows us to distinguish\nregions of the capsid with well-ordered DNA from the disordered central core.\nWe employ a state-of-the-art numerical algorithm based on the finite element\nmethod to find equilibrium states of the encapsidated DNA and calculate the\ncorresponding pressure. With a data-oriented parameter selection strategy, the\nmethod yields phase spaces of the pressure and the radius of the disordered\ncore, in terms of relevant dimensionless parameters, rendering the proposed\nalgorithm into a preliminary bacteriophage designing tool. The presence of the\norder parameter also has the unique role of allowing for non-smooth capsid\ndomains as well as accounting for knot locations of the DNA.",
        "positive": "Thinning and thickening in active microrheology: When pulling a probe particle in a many-particle system with fixed velocity,\nthe probe's effective friction, defined as average pulling force over its\nvelocity, $\\gamma_{eff}:=\\langle F_{ex}\\rangle/u$, first keeps constant (linear\nresponse), then decreases (thinning) and finally increases (thickening). We\npropose a three-time-scales picture (TTSP) to unify thinning and thickening\nbehaviour. The points of the TTSP are that there are three distinct time scales\nof bath particles: diffusion, damping, and single probe-bath (P-B) collision;\nthe dominating time scales, which are controlled by the pulling velocity,\ndetermine the behaviour of the probe's friction. We confirm the TTSP by\nLangevin dynamics simulation. Microscopically, we find that for computing the\neffective friction, Maxwellian distribution of bath particles' velocities works\nin low Reynolds number (Re) but fails in high Re. It can be understood based on\nthe microscopic mechanism of thickening obtained in the $T=0$ limit. Based on\nthe TTSP, we explain different thinning and thickening observations in some\nearlier literature."
    },
    {
        "anchor": "Fast dynamics and emergent topological defects in long-range interacting\n  particle systems: Long-range interacting systems exhibit unusual physical properties not shared\nby systems with short-range interactions. Understanding the dynamical and\nstatistical effects of long-range interactions yields insights into a host of\nphysical systems in nature and industry. In this work, we investigate the\nclassical microscopic dynamics of screened Coulomb interacting particles\nconfined in the disk, and reveal the featured dynamics and emergent statistical\nregularities created by the long-range interaction. We highlight the long-range\ninteraction driven fast single-particle and collective dynamics, and the\nemergent topological defect structure. This work suggests the rich physics\narising from the interplay of long-range interaction, topology and dynamics.",
        "positive": "Delocalization transitions of semi-flexible manifolds: Semi-flexible manifolds such as fluid membranes or semi-flexible polymers\nundergo delocalization transitions if they are subject to attractive\ninteractions. We study manifolds with short-ranged interactions by\nfield-theoretic methods based on the operator product expansion of local\ninteraction fields. We apply this approach to manifolds in a random potential.\nRandomness is always relevant for fluid membranes, while for semi-flexible\npolymers there is a first order transition to the strong coupling regime at a\nfinite temperature."
    },
    {
        "anchor": "The secondary structure of RNA under tension: We study the force-induced unfolding of random disordered RNA or\nsingle-stranded DNA polymers. The system undergoes a second order phase\ntransition from a collapsed globular phase at low forces to an extensive\nnecklace phase with a macroscopic end-to-end distance at high forces. At low\ntemperatures, the sequence inhomogeneities modify the critical behaviour. We\nprovide numerical evidence for the universality of the critical exponents\nwhich, by extrapolation of the scaling laws to zero force, contain useful\ninformation on the ground state (f=0) properties. This provides a good method\nfor quantitative studies of scaling exponents characterizing the collapsed\nglobule. In order to get rid of the blurring effect of thermal fluctuations we\nrestrict ourselves to the groundstate at fixed external force. We analyze the\nstatistics of rearrangements, in particular below the critical force, and point\nout its implications for force-extension experiments on single molecules.",
        "positive": "Theory of Elastic Microphase Separation: Elastic microphase separation refers to equilibrium patterns that form by\nphase separation in elastic gels. Recent experiments revealed a continuous\nphase transition from the homogeneous phase to a regularly patterned phase,\nwhose period decreased for stiffer systems. We here propose a model that\ncaptures these observations. The model combines a continuous field of the\nelastic component to describe phase separation with nonlocal elasticity theory\nto capture the gel's microstructure. Analytical approximations unveil that the\npattern period is determined by the geometric mean between the elasto-capillary\nlength and a microscopic length scale of the gel. Our theory highlights the\nimportance of nonlocal elasticity in soft matter systems, reveals the mechanism\nof elastic microphase separation, and will improve the engineering of such\nsystems."
    },
    {
        "anchor": "A phase separation of active colloidal suspension via Quorum-sensing: We present the Brownian dynamics simulation of active colloidal suspension in\ntwo dimensions, where the self-propulsion speed of a colloid is regulated\naccording to the local density sensed by it. The role of\nconcentration-dependent motility on the phase-separation of colloids and their\ndynamics is investigated in detail. Interestingly, the system phase separates\nat a very low packing fraction ($\\Phi\\approx 0.125$) at higher self-propulsion\nspeeds ($\\text{Pe}$), which coexists with a homogeneous phase and attains\nlong-range crystalline order beyond a transition point. The transition point is\nquantified here from the local density profiles, local and global-bond order\nparameters. We have shown that the phase diagram's characteristics are\nqualitatively akin to the active Brownian particle (ABP) model. Moreover, our\ninvestigation reveals that the density-dependent motility amplifies the\nslow-down of the directed speed, which facilitates phase-separation even at low\npacking fractions. The effective diffusivity shows a crossover from quadratic\nrise to a power-law behavior of exponent $3/2$ with $\\text{Pe}$ in the\nphase-separated regime. Furthermore, we have shown that the effective diffusion\ndecreases exponentially with packing fraction in the phase-separated regime\nwhile linear decrease in the single phase regime.",
        "positive": "From Feynman's ratchet to timecrystalline molecular motors: Cats use the connection governing parallel transport in the space of shapes\nto land safely on their feet. Here we argue that this connection also explains\nthe impressive performance of molecular motors by enabling molecules to evade\nconclusions of Feynman's ratchet-and-pawl analysis. We first demonstrate, using\nsimple molecular models, how directed rotational motion can emerge from shape\nchanges even without angular momentum. We then computationally design knotted\npolyalanine molecules and show how their shape space connection organizes\nindividual atom thermal vibrations into collective rotational motion,\nindependently of angular momentum. Our simulations show that rotational motion\narises effortlessly even in ambient water, making the molecule an effective\ntheory time crystal. Our findings have potential for practical molecular motor\ndesign and engineering and can be verified through high-precision nuclear\nmagnetic resonance measurements."
    },
    {
        "anchor": "A fresh look at the vibrational and thermodynamic properties of liquids\n  within the soft potential model: Contrary to the case of solids and gases, where Debye theory and kinetic\ntheory offer a good description for most of the physical properties, a complete\ntheoretical understanding of the vibrational and thermodynamic properties of\nliquids is still missing. Liquids exhibit a vibrational density of states\n(VDOS) which does not obey Debye law, and a heat capacity which decreases\nmonotonically with temperature, rather than growing as in solids. Despite many\nattempts, a simple, complete and widely accepted theoretical framework able to\nformally derive the aforementioned properties has not been found yet. Here, we\nrevisit one of the theoretical proposals, and in particular we re-analyze the\nproperties of liquids within the soft-potential model, originally formulated\nfor glasses. We confirm that, at least at a qualitative level, many\ncharacteristic properties of liquids can be rationalized within this model. We\ndiscuss the validity of several phenomenological expressions proposed in the\nliterature for the density of unstable modes, and in particular for its\ntemperature and frequency dependence. We discuss the role of negative curvature\nregions and unstable modes as fundamental ingredients to have a linear in\nfrequency VDOS. Finally, we compute the heat capacity within the soft potential\nmodel for liquids and we show that it decreases with temperature, in agreement\nwith experimental and simulation data.",
        "positive": "Programmable patchy particles for materials design: Direct design of complex functional materials would revolutionize\ntechnologies ranging from printable organs to novel clean energy devices.\nHowever, even incremental steps towards designing functional materials have\nproven challenging. If the material is constructed from highly complex\ncomponents, the design space of materials properties rapidly becomes too\ncomputationally expensive to search. On the other hand, very simple components\nsuch as uniform spherical particles are not powerful enough to capture rich\nfunctional behavior. Here, we introduce a differentiable materials design model\nwith components that are simple enough to design yet powerful enough to capture\ncomplex materials properties: rigid bodies composed of spherical particles with\ndirectional interactions (patchy particles). We showcase the method with\nself-assembly designs ranging from open lattices to self-limiting clusters, all\nof which are notoriously challenging design goals to achieve using purely\nisotropic particles. By directly optimizing over the location and interaction\nof the patches on patchy particles using gradient descent, we dramatically\nreduce the computation time for finding the optimal building blocks."
    },
    {
        "anchor": "Liquid dynamics in partially crystalline glycerol: We present a dielectric study on the dynamics of supercooled glycerol during\ncrystallization. We explore the transformation into a solid phase in real time\nby monitoring the temporal evolution of the amplitude of the dielectric signal.\nNeither the initial nucleation or the crystal growth influence the liquid\ndynamics visibly. For one of the samples studied, a tiny fraction of glycerol\nremained in the disordered state after the end of the transition. We examined\nthe nature of the alpha relaxation in this frustrated crystal and find that it\nis virtually identical to the bulk dynamics. In addition to that, we have found\nno evidence that supercooled glycerol transforms into a peculiar phase where\neither a new solid amorphous state or nano-crystals dispersed in a liquid\nmatrix are formed.",
        "positive": "Pair Interaction Potentials of Colloids by Extrapolation of Confocal\n  Microscopy Measurements of Collective Structure: A method for measuring the pair interaction potential between colloidal\nparticles by extrapolation measurement of collective structure to infinite\ndilution is presented and explored using simulation and experiment. The method\nis particularly well suited to systems in which the colloid is fluorescent and\nrefractive index matched with the solvent. The method involves characterizing\nthe potential of mean force between colloidal particles in suspension by\nmeasurement of the radial distribution function using 3D direct visualization.\nThe potentials of mean force are extrapolated to infinite dilution to yield an\nestimate of the pair interaction potential, $U(r)$. We use Monte Carlo (MC)\nsimulation to test and establish our methodology as well as to explore the\neffects of polydispersity on the accuracy. We use poly-12-hydroxystearic\nacid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in\nthe solvent dioctyl phthalate (DOP) to test the method and assess its accuracy\nfor three different repulsive systems for which the range has been manipulated\nby addition of electrolyte."
    },
    {
        "anchor": "Precursor Film Spreading during Liquid Imbibition in Nanoporous Photonic\n  Crystals: When a macroscopic droplet spreads, a thin precursor film of liquid moves\nahead of the advancing liquid-solid-vapor contact line. Whereas this phenomenon\nhas been explored extensively for planar solid substrates, its presence in\nnanostructured geometries has barely been studied so far, despite its\nimportance for many natural and technological fluid transport processes. Here\nwe use porous photonic crystals in silicon to resolve by light interferometry\ncapillarity-driven spreading of liquid fronts in pores of few nanometers in\nradius. Upon spatiotemporal rescaling the fluid profiles collapse on master\ncurves indicating that all imbibition fronts follow a square-root-of-time\nbroadening dynamics. For the simple liquid (glycerol) a sharp front with a\nwidening typical of Lucas-Washburn capillary-rise dynamics in a medium with\npore-size distribution occurs. By contrast, for a polymer (PDMS) a precursor\nfilm moving ahead of the main menisci entirely alters the nature of the\nnanoscale transport, in agreement with predictions of computer simulations.",
        "positive": "Resolving solution conformations of the model semi-flexible\n  polyelectrolyte homogalacturonan using molecular dynamics simulations and\n  small-angle x-ray scattering: The conformation of polyelectrolytes in the solution state has long been of\ninterest in polymer science. Herein we utilize all atom molecular dynamics\nsimulations (MD) and small-angle x-ray scattering experiments (SAXS) to\nelucidate the molecular structure of the model polyelectrolyte\nhomogalacturonan. Several degrees of polymerization were studied and in\naddition partial methylesterification of the otherwise charge-carrying carboxyl\ngroups was used in order to generate samples with varying intra-chain charge\ndistributions. It is shown that at length scales above around 1 nm the\nconformation of isolated chains has surprisingly little dependence on the\ncharge distribution or the concentration of attendant monovalent salts,\nreflective of the intrinsic stiffness of the saccharide rings and the dynamical\nconstraints of the glycosidic linkage. Indeed the conformation of isolated\nchains over all accessible length-scales is well described by the atomic\nco-ordinates available from fibre diffraction studies. Furthermore, in more\nconcentrated systems it is shown that, after careful analysis of the SAXS data,\nthe form of the inter-particle effects heralded by the emergence of a so-called\npolyelectrolyte peak, can be extracted, and that this phenomena can be\nreproduced by multiple chain MD simulations."
    },
    {
        "anchor": "Heterogeneous Dynamical Relaxations in a Lane Forming Liquid: The connection between domain relaxations at individual scales and the\ncollective heterogeneous response in non-equilibrium systems is a topic of\nprofound interest in recent times. In a model sys- tem of constantly driven\noppositely charged binary colloidal suspension, we probe such relaxations as\nthe elongated lanes of likely charges interact with increasing field in the\northogonal plane using Brownian Dynamics simulations. We show that the system\nundergoes a structural and dynamical cross-over: from an initial fast-relaxing\nhomogeneous phase to a heterogeneous lane phase following a slow relaxation via\nan intermediate phase with mixed relaxation. Our observations also affirm the\ncoexistence of multiple time and length scales in this phase. Unlike glasses,\nthese time and length scales are not separated by orders of magnitude, they are\ncomparable in magnitudes. Using a phenomenological model, we, further,\nreinforce that these competing relaxations are a manifesta- tion of\nheterogeneity in diffusion which is rather generic in systems with such\ncompeting relaxations.",
        "positive": "Orientational instability and spontaneous rotation of active nematic\n  droplets: In experiments, an individual chemically active liquid crystal (LC) droplet\nsubmerged in the bulk of a surfactant solution may self-propel along a\nstraight, helical, or random trajectory. In this paper, we develop a minimal\nmodel capturing all three types of self-propulsion trajectories of a drop in\nthe case of a nematic LC with homeotropic anchoring at LC-fluid interface. We\nemulate the director field within the drop by a single preferred polarization\nvector that is subject of two reorientation mechanisms, namely, the internal\nflow-induced displacement of the hedgehog defect and the droplet's rotation.\nWithin this reduced-order model, the coupling between the nematic ordering of\nthe drop and the surfactant transport is represented by variations of the\ndroplet's interfacial properties with nematic polarization. Our analysis\nreveals that a novel mode of orientational instability emerges from the\ncompetition of the two reorientation mechanisms and is characterized by a\nspontaneous rotation of the self-propelling drop responsible for helical\nself-propulsion trajectories. In turn, we also show that random trajectories in\nisotropic and nematic drops alike stem from the advection-driven transition to\nchaos. The succession of the different propulsion modes is consistent with\nexperimentally-reported transitions in the shape of droplet trajectories as the\ndrop size is varied."
    },
    {
        "anchor": "Raman coupler for a trapped two-component quantum-degenerate Fermi gas: We investigate theoretically the Raman coupling between two internal states\nof a trapped low-density quantum-degenerate Fermi gas. In general, the trap\nfrequencies associated with the two internal states can be different, leading\nto the onset of collapses and revivals in the population difference of the two\ninternal states. This behavior can be changed drastically by two-body\ncollisions. In particular, we show that under appropriate conditions they can\nsuppress the dephasing leading to the collapse of the population difference,\nand restore almost full Rabi oscillations between the two internal states.\nThese results are compared and contrasted to those for a quantum-degenerate\nbosonic gas.",
        "positive": "Tetrahedral Order in Liquid Crystals: We review the impact of tetrahedral order on the macroscopic dynamics of\nbent-core liquid crystals. We discuss tetrahedral order comparing with other\ntypes of orientational order, like nematic, polar nematic, polar smectic, and\nactive polar order. In particular, we present hydrodynamic equations for\nphases, where only tetrahedral order exists or tetrahedral order is combined\nwith nematic order. Among the latter we discriminate between three cases, where\nthe nematic director (a) orients along a 4-fold, or (b) along a 3-fold symmetry\naxis of the tetrahedral structure. For the optically isotropic T_d phase, which\nonly has tetrahedral order, we focus on the coupling of flow with e.g.\ntemperature gradients and on the specific orientation behavior in external\nelectric fields. For the transition to the nematic phase, electric fields lead\nto a temperature shift that is linear in the field strength. Electric fields\ninduce nematic order, again linear in the field strength. If strong enough,\nelectric fields can change the tetrahedral structure and symmetry leading to a\npolar phase. We briefly deal with the T phase that arises when tetrahedral\norder occurs in a system of chiral molecules. To case (a) belong (i) the\nnon-polar, achiral, optically uniaxial D2d phase with ambidextrous helicity and\nwith orientational frustration in external fields, (ii) the non-polar\ntetragonal S4 phase, (iii) the non-polar, orthorhombic D2 phase that is\nstructurally chiral featuring ambidextrous chirality, (iv) the polar\northorhombic C2v phase, and (v) the polar monoclinic C2 phase. Case (b) results\nin a trigonal C3v phase that behaves like a biaxial polar nematic phase.\nFinally we discuss some experiments that show typical effects related to the\nexistence of tetrahedral order."
    },
    {
        "anchor": "Effects of Average Number of Platelets Through the Thickness and\n  Platelet Width on the Mechanical Properties of Discontinuous Fiber Composites: In this study, we experimentally and numerically investigate the evolution of\nthe tensile material properties of Discontinuous Fiber Composites (DFCs) with\nan increasing average number of platelets through the thickness for two\ndifferent platelet widths. The results show that both the number of platelets\nand the platelet width have significant effects on the tensile modulus and\nstrength. We find that not only the average mechanical properties but also\ntheir coefficients of variation change according to the different DFC\nmesostructures. To understand the relationship between material morphology at\nthe mesoscale and corresponding material properties, we developed a random\nplatelet mesostructure generation algorithm combined with explicit finite\nelement models. Leveraging the computational tools, we find that moduli and\nstrength increase with increasing average number of platelets through the\nthickness. The increasing trend continues until reaching an asymptotic limit at\nabout 45 layers through the thickness for the narrow platelets and 27 layers\nfor the square platelets. In the study, we address the importance of having\naccurate simulations of the mesostructure to match not only the average modulus\nand strength but also their associated coefficients of variation. We show that\nit is possible to accurately predict the tensile material properties of DFCs,\nincluding their B-basis design values. This is a quintessential condition for\nthe adoption of DFCs in structural applications.",
        "positive": "Comment on ``Large Slip of Aqueous Liquid Flow over a Nanoengineered\n  Superhydrophobic Surface'' by C-H Choi and C Kim: In a recent Letter (Phys. Rev. Lett. vol 96, 066001 (2006), ref [1]), Choi\nand Kim reported slip lengths of a few tens of microns for water on\nnanoengineered superhydrophobic surfaces, on the basis of rheometry\n(cone-and-plate) measurements. We show that the experimental uncertainty in the\nexperiment of Ref. [1], expressed in term of slip lengths, lies in the range 20\n- 100 micrometers, which is precisely the order of magnitude of the reported\nslip lengths. Moreover we point out a systematic bias expected on the\nsuperhydrophobic surfaces. We thus infer that it is not possible to draw out\nany conclusion concerning the existence of huge slip lengths in the system\nstudied by Choi and Kim."
    },
    {
        "anchor": "Density Functional Theory of Model Systems with the Biaxial Nematic\n  Phase: Present work is a theoretical study on the stability of the thermotropic\nbiaxial nematic liquid crystal phase in model systems. Its main aim is to\npresent the phase diagrams of spatially uniform liquid mesophases and to\nidentify the molecular parameters that influence the stability of the biaxial\nnematic. The diagrams are obtained by means of the Local Density Functional\nTheory in low density approximation, and the relation between the molecular\nparameters of the models and macroscopic properties of the system close to the\ntransition point are obtained by means of bifurcation analysis. We consider\nthree model systems; the so-called L=2 model (the lowest coupling model of the\norientational part of pair potential), the biaxial Gay-Berne interaction, and\nthe bent-core system. For the second one, we also briefly investigate the\ntemperature dependence of elastic constants in rod-like regime and in the\nvicinity of the Landau point and comment on the smectic phases. In every case\nwe take into account rigid molecules. We find that the Landau points acquired\nfrom the square root rule for hard biaxial ellipsoids retain its significance,\nand provide qualitatively correct estimations of Landau points positions for\nGay-Berne biaxial ellipsoids. In case of the bent-core model molecules build\nfrom uniaxial and biaxial Gay-Berne ellipsoids we find that the dipole-dipole\ninteraction and degree of arms biaxiality change the stability of the biaxial\nnematic phase.",
        "positive": "Cooling jug physics: We discuss the physics of the pot-in-pot cooler. By balancing temperature\ndecrease due to evaporation and temperature increase due to heat exchange, we\nfind the equilibrium temperature of the pot. In this simplified model, the\ncooling jug acts as a psychrometer, and the theoretical prediction of our model\nis in a good agreement with psychrometric tables. Next, we study dynamics of\nthe jug cooling. The cooling rate is limited by water vapour diffusion through\nair, heat conduction through air, and heat conduction through the body of the\njug. The derived rate of temperature decrease is in general agreement with the\nresult of our experiment. In the end, we discuss some additional factors, such\nas capillary effects in the raw clay, water viscosity in the capillaries, and\nimpact of complex shape of the jug."
    },
    {
        "anchor": "Motional dressed states in a Bose condensate: Superfluidity at\n  supersonic speed: We present an exact analytic solution of a nonlinear Schr\\\"odinger field\ninteracting with a moving potential (obstacle) at supersonic speed. We show\nthat the field forms a stable shape-invariant structure localized around the\nobstacle --- a dressing effect that protects the field against excitations by\nthe obstacle.",
        "positive": "Helix formation in linear achiral dendronized polymers. A computer\n  simulation study: We present a molecular simulation study of the structure of linear\ndendronized polymers. We use excluded volume interactions in the context of a\ngeneric coarse-grained molecular model whose geometrical parameters are tuned\nto represent a poly(para-phenylene) backbone with benzyl ether, Frechet type\ndendrons. We apply Monte Carlo sampling in order to investigate the formation\nof packing-induced chiral structures along the polymer backbone of these\nchemically non-chiral systems. We find that helical structures can be formed,\nusually with defects consisting of domains with reversed helical handedness.\nClear signs of helical arrangements of the dendrons begin to appear for\ndendritic generation g=4, while for g=5 these arrangements dominate and perfect\nhelices can even be observed as equilibrium structures obtained from certain\ntypes of starting configurations."
    },
    {
        "anchor": "Excitation-assisted inelastic processes in trapped Bose-Einstein\n  condensates: We find that inelastic collisional processes in Bose-Einstein condensates\ninduce local variations of the mean-field interparticle interaction and are\naccompanied by the creation/annihilation of elementary excitation. The physical\npicture is demonstrated for the case of three body recombination in a trapped\ncondensate. For a high trap barrier the production of high energy trapped\nsingle particle excitations results in a strong increase of the loss rate of\natoms from the condensate.",
        "positive": "Non-axisymmetric instability of shear-banded Taylor-Couette flow: Recent experiments show that shear-banded flows of semi-dilute worm-like\nmicelles in Taylor-Couette geometry exhibit a flow instability in the form of\nTaylor-like vortices. Here we perform the non-axisymmetric linear stability\nanalysis of the diffusive Johnson-Segalman model of shear banding and show that\nthe nature of this instability depends on the applied shear rate. For the\nexperimentally relevant parameters, we find that at the beginning of the stress\nplateau the instability is driven by the interface between the bands, while\nmost of the stress plateau is occupied by the bulk instability of the\nhigh-shear-rate band. Our work significantly alters the recently proposed\nstability diagram of shear-banded flows based on axisymmetric analysis."
    },
    {
        "anchor": "Escape dynamics of active particles in multistable potentials: Rare transitions between long-lived metastable states underlie a great\nvariety of physical, chemical and biological processes. Our quantitative\nunderstanding of reactive mechanisms has been driven forward by the insights of\ntransition state theory. In particular, the dynamic framework developed by\nKramers marks an outstanding milestone for the field. Its predictions, however,\ndo not apply to systems driven by non-conservative forces or correlated noise\nhistories. An important class of such systems are active particles, prominent\nin both biology and nanotechnology. Here, we trap a silica nanoparticle in a\nbistable potential. To emulate an active particle, we subject the particle to\nan engineered external force that mimics self-propulsion. We investigate the\nactive particle's transition rate between metastable states as a function of\nfriction and correlation time of the active force. Our experiments reveal the\nexistence of an optimal correlation time where the transition rate is\nmaximized. This novel \\emph{active turnover} is reminiscent of the much\ncelebrated Kramers turnover despite its fundamentally different origin. Our\nobservations are quantitatively supported by a theoretical analysis of a\none-dimensional model. Besides providing a deeper understanding of the escape\ndynamics of active particles in multistable potentials, our work establishes a\nnew, versatile experimental platform to study particle dynamics in\nnon-equilibrium settings.",
        "positive": "Colloid-Polymer Interplay in the Local Longitudinal Fluctuations of\n  F-actin Solutions: We study the motion of single trapped microtracers immersed in F-actin\nsolutions by optical trapping interferometry in order to clarify the observed\nvariability of their anomalous power-law exponent. We obtain a local 7/8\nexponent only for non-adsorbing polymer at low optical trapping forces, a value\nwhich decreases when increasing the trap stiffness. The velocity\nautocorrelation function confirms the complex interplay in the colloid-polymer\nsystem even under the influence of small external forces and shows an\nadditional constant power-law exponent for the depleted particles."
    },
    {
        "anchor": "Holographic optical trapping: Holographic optical tweezers use computer-generated holograms to create\narbitrary three-dimensional configurations of single-beam optical traps useful\nfor capturing, moving and transforming mesoscopic objects. Through a\ncombination of beam-splitting, mode forming, and adaptive wavefront correction,\nholographic traps can exert precisely specified and characterized forces and\ntorques on objects ranging in size from a few nanometers to hundreds of\nmicrometers. With nanometer-scale spatial resolution and real-time\nreconfigurability, holographic optical traps offer extraordinary access to the\nmicroscopic world and already have found applications in fundamental research\nand industrial applications.",
        "positive": "Ordering of Binary Colloidal Crystals by Random Potentials: Structural defects are ubiquitous in condensed matter, and not always a\nnuisance. For example, they underlie phenomena such as Anderson localization\nand hyperuniformity, and they are now being exploited to engineer novel\nmaterials. Here, we show experimentally that the density of structural defects\nin a 2D binary colloidal crystal can be engineered with a random potential. We\ngenerate the random potential using an optical speckle pattern, whose induced\nforces act strongly on one species of particles (strong particles) and weakly\non the other (weak particles). Thus, the strong particles are more attracted to\nthe randomly distributed local minima of the optical potential, leaving a trail\nof defects in the crystalline structure of the colloidal crystal. While, as\nexpected, the crystalline ordering initially decreases with increasing fraction\nof strong particles, the crystalline order is surprisingly recovered for\nsufficiently large fractions. We confirm our experimental results with\nparticle-based simulations, which permit us to elucidate how this non-monotonic\nbehavior results from the competition between the particle-potential and\nparticle-particle interactions."
    },
    {
        "anchor": "Dynamic compartmentalization of bacteria: accurate division in E. coli: Positioning of the midcell division plane within the bacterium E. coli is\ncontrolled by the min system of proteins: MinC, MinD and MinE. These proteins\ncoherently oscillate from end to end of the bacterium. We present a\nreaction--diffusion model describing the diffusion of min proteins along the\nbacterium and their transfer between the cytoplasmic membrane and cytoplasm.\nOur model spontaneously generates protein oscillations in good agreement with\nexperiments. We explore the oscillation stability, frequency and wavelength as\na function of protein concentration and bacterial length.",
        "positive": "Complex dynamics of knotted filaments in shear flow: Coarse-grained simulations are used to demonstrate that knotted filaments in\nshear flow at zero Reynolds number exhibit remarkably rich dynamic behaviour.\nFor stiff filaments that are weakly deformed by the shear forces, the knotted\nfilaments rotate like rigid objects in the flow. But away from this regime the\ninterplay between between shear forces and the flexibility of the filament\nleads to intricate regular and chaotic modes of motion that can be divided into\ndistinct families. The set of accessible mode families depends to first order\non a dimensionless number that relates the filament length, the elastic\nmodulus, the friction per unit length and the shear rate."
    },
    {
        "anchor": "Geometry and mechanics of microdomains in growing bacterial colonies: Bacterial colonies are abundant on living and nonliving surfaces and are\nknown to mediate a broad range of processes in ecology, medicine, and industry.\nAlthough extensively researched, from single cells to demographic scales, a\ncomprehensive biomechanical picture, highlighting the cell-to-colony dynamics,\nis still lacking. Here, using molecular dynamics simulations and continuous\nmodeling, we investigate the geometrical and mechanical properties of a\nbacterial colony growing on a substrate with a free boundary and demonstrate\nthat such an expanding colony self-organizes into a \"mosaic\" of microdomains\nconsisting of highly aligned cells. The emergence of microdomains is mediated\nby two competing forces: the steric forces between neighboring cells, which\nfavor cell alignment, and the extensile stresses due to cell growth that tend\nto reduce the local orientational order and thereby distort the system. This\ninterplay results in an exponential distribution of the domain areas and sets a\ncharacteristic length scale proportional to the square root of the ratio\nbetween the system orientational stiffness and the magnitude of the extensile\nactive stress. Our theoretical predictions are finally compared with\nexperiments with freely growing E. coli microcolonies, finding quantitative\nagreement.",
        "positive": "High-resolution detection of Brownian motion for quantitative Optical\n  Tweezers experiments: We have developed a new in situ method to calibrate optical tweezers\nexperiments and simultaneously measure the size of the trapped particle or the\nviscosity of the surrounding fluid. The positional fluctuations of the trapped\nparticle are recorded with a high-bandwidth photodetector. Next, we compute the\nmean-square displacement, as well as the velocity autocorrelation function of\nthe sphere and compare it to the theory of Brownian motion including\nhydrodynamic memory effects. A careful measurement and analysis of the time\nscales characterizing the dynamics of the harmonically bound sphere fluctuating\nin a viscous medium then directly yields all relevant parameters. Finally, we\ntest the method for different optical trap strengths, with different bead sizes\nand in different fluids, and we find excellent agreement with the values\nprovided by the manufacturers. The proposed approach overcomes the most\ncommonly encountered limitations in precision when analyzing the power spectrum\nof position fluctuations in the region around the corner frequency. These low\nfrequencies are usually prone to errors due to drift, limitations in the\ndetection and trap linearity as well as short acquisition times resulting in\npoor statistics. Furthermore, the strategy can be generalized to Brownian\nmotion in more complex environments, provided the adequate theories are\navailable."
    },
    {
        "anchor": "Theory of Capillary Tension and Interfacial Dynamics of Motility-Induced\n  Phases: The statistical mechanics of equilibrium interfaces has been well-established\nfor over a half century. In the last decade, a wealth of observations have made\nincreasingly clear that a new perspective is required to describe interfaces\narbitrarily far from equilibrium. In this Article, beginning from microscopic\nparticle dynamics that break time-reversal symmetry, we systematically derive\nthe interfacial dynamics of coexisting motility-induced phases. Doing so allows\nus to identify the athermal energy scale that excites interfacial fluctuations\nand the nonequilibrium surface tension that resists these excitations. In\naddition to establishing an active capillary-wave theory, our theory identifies\nthat, in contrast to equilibrium fluids, this active surface tension contains\ncontributions arising from nonconservative forces which act to suppress\ninterfacial fluctuations. The identified contribution bares a remarkable\nresemblance with that envisioned by Edwards and Wilkinson in their description\nof the surface of athermal granular materials, suggesting that\ndynamically-stabilized interfaces may be a phenomenon common to a wide class of\nnonequilibrium systems.",
        "positive": "Orienting thin films of lamellar block copolymer: the combined effect of\n  mobile ions and electric field: We study thin films of A/B diblock copolymer in a lamellar phase confined\nbetween two parallel plates (electrodes) that impose a constant voltage across\nthe film. The weak-segregation limit is explored via a Ginzburg-Landau-like\nfree-energy expansion. We focus on the relative stability of parallel and\nperpendicular orientations of the lamellar phase, and how they are affected by\nvariation of four experimental controllable parameters: addition of free ions,\nthe difference in ionic solubilities between the A and B blocks, the dielectric\ncontrast between the A/B blocks, and the preferential interaction energy of the\nplates with the blocks. It is found that, in general, the addition of ions\nlowers the critical voltage needed to reorient the lamellae from being parallel\nto the plates, to being perpendicular to them. The largest reduction in\ncritical voltage is obtained when the ions are preferentially solubilized in\nthe block that is not preferred by the plates. This reduction is even further\nenhanced when the dielectric constant of this block has the higher value. These\npredictions are all subject to experimental verification."
    },
    {
        "anchor": "Point-spread function engineering enhances digital Fourier microscopy: While numerous optical methods exist to probe the dynamics of biological or\ncomplex fluid samples, in recent years digital Fourier microscopy techniques,\nlike differential dynamic microscopy, have emerged as ways to efficiently\ncombine elements of imaging and scattering methods. Here, we demonstrate,\nthrough experiments and simulations, how point-spread function engineering can\nbe used to extend the reach of differential dynamic microscopy.",
        "positive": "Entropic force in a dilute solution of real ring polymer chains with\n  different topological structures in a slit of two parallel walls with mixed\n  boundary conditions: The molecular dynamics simulations were used to obtain the radius of gyration\nof real ring polymer chains with different topological structures consisting of\n360 monomers. We focus on the entropic force which is exerted by a dilute\nsolution of ring polymer chains of different topological structures with the\nexcluded volume interaction (EVI) in a good solvent on the confining parallel\nwalls of a slit geometry. We consider mixed boundary conditions of one\nrepulsive wall and the other one at the adsorption threshold. The obtained\nmolecular dynamics simulation results for a wide slit region demonstrate a\nqualitative agreement with previous analytical results for ideal ring polymers.\nThese results could lead to interesting potential applications in materials\nengineering and improve understanding of some biological processes suggested in\nthe paper. Additionally, they could be applied in micro- and\nnano-electromechanical devices (MEMS and NEMS) in order to reduce the static\nfriction."
    },
    {
        "anchor": "Dumb-bell swimmers: We investigate the way in which oscillating dumb-bells, a simple microscopic\nmodel of apolar swimmers, move at low Reynold's number. In accordance with\nPurcell's Scallop Theorem a single dumb-bell cannot swim because its stroke is\nreciprocal in time. However the motion of two or more dumb-bells, with mutual\nphase differences, is not time reversal invariant, and hence swimming is\npossible. We use analytical and numerical solutions of the Stokes equations to\ncalculate the hydrodynamic interaction between two dumb-bell swimmers and to\ndiscuss their relative motion. The cooperative effect of interactions between\nswimmers is explored by considering first regular, and then random arrays of\ndumb-bells. We find that a square array acts as a micropump. The long time\nbehaviour of suspensions of dumb-bells is investigated and compared to that of\nmodel polar swimmers.",
        "positive": "Influence of Polymer Shape on Depletion Potentials and Crowding in\n  Colloid-Polymer Mixtures: Depletion-induced interactions between colloids in colloid-polymer mixtures\ndepend in range and strength on size, shape, and concentration of depletants.\nCrowding by colloids in turn affects shapes of polymer coils, such as\nbiopolymers in biological cells. By simulating hard-sphere colloids and\nrandom-walk polymers, modeled as fluctuating ellipsoids, we compute\ndepletion-induced potentials and polymer shape distributions. Comparing results\nwith exact density-functional theory calculations, molecular simulations, and\nexperiments, we show that polymer shape fluctuations play an important role in\ndepletion and crowding phenomena."
    },
    {
        "anchor": "Binary Mixtures of Particles with Different Diffusivities Demix: The influence of size differences, shape, mass and persistent motion on phase\nseparation in binary mixtures has been intensively studied. Here we focus on\nthe exclusive role of diffusivity differences in binary mixtures of equal-sized\nparticles. We find an effective attraction between the less diffusive\nparticles, which are essentially caged in the surrounding species with the\nhigher diffusion constant. This effect leads to phase separation for systems\nabove a critical size: A single close-packed cluster made up of the less\ndiffusive species emerges. Experiments for testing of our predictions are\noutlined.",
        "positive": "Tracer diffusion in crowded solutions of sticky polymers: Macromolecular diffusion in strongly confined geometries and crowded\nenvironments is still to a large extent an open subject in soft matter physics\nand biology. In this paper, we employ large-scale Langevin dynamics simulations\nto investigate how the diffusion of a tracer is influenced by the combined\naction of excluded-volume and weak attractive crowder-tracer interactions. We\nconsider two species of tracers, standard hard-core particles described by the\nWeeks-Chandler-Andersen (WCA) repulsive potential and core-softened (CS)\nparticles, which model, e.g., globular proteins, charged colloids and\nnanoparticles covered by polymeric brushes. These systems are characterized by\nthe presence of two length scales in the interaction and can show water-like\nanomalies in their diffusion, stemming from the inherent competition between\ndifferent length scales. Here we report a comprehensive study of both diffusion\nand structure of these two tracer species in an environment crowded by quenched\nconfigurations of polymers at increasing density. We analyze in detail how the\ntracer-polymer affinity and the system density affect transport as compared to\nthe emergence of specific static spatial correlations. In particular, we find\nthat, while hardly any differences emerge in the diffusion properties of WCA\nand CS particles, the propensity to develop structural order for large crowding\nis strongly frustrated for CS particles. Surprisingly, for large enough\naffinity for the crowding matrix, the diffusion coefficient of WCA tracers\ndisplay a non-monotonic trend as their density is increased when compared to\nthe zero affinity scenario. This water-like anomaly turns out to be even larger\nthan what observed for CS particle and appears to be rooted in a similar\ncompetition between excluded-volume and affinity effects."
    },
    {
        "anchor": "Gradient flow model of mode-III fracture in Maxwell-type viscoelastic\n  materials: We formulate a phase field crack growth model for mode III fracture in a\nMaxwell-type viscoelastic material. To describe viscoelastic relaxation, a\nfield variable of viscously flowed strain is employed in addition to a\ndisplacement field and damage phase field used in the original elastic model.\nUnlike preceding models constructed in the mechanical engineering community,\nour model is based only on the generic procedure for driving (uni-directional)\ngradient flow system from a physically natural system energy and employ no\nadditional assumption such as the super-imposed relations for stress and strain\n(and their time derivatives) valid only for linear viscoelasticity. Numerical\nsimulations indicate that the competition between increase in deformation by\napplied loading and the viscoelastic relaxation determines whether a distinct\ncrack propagation has occurred from an initial crack. Furthermore, we consider\nthe numerical results from an energetic perspective.",
        "positive": "Ferroelectric Nematic Droplets in their Isotropic Melt: The isotropic to ferroelectric nematic liquid transition had been\ntheoretically studied over one hundred years ago, but its experimental studies\nare rare. Here we present polarizing optical microscopy studies and theoretical\nconsiderations of ferroelectric nematic liquid crystal droplets coexisting with\nthe isotropic melt. We find that the droplets have flat pancake-like shapes\nthat are thinner than the sample thickness as long as there is a room to\nincrease the lateral droplet size. In the center of the droplets a wing shaped\ndefect with low birefringence is present that moves perpendicular to a weak\nin-plane electric field, and then extends and splits in two at higher fields.\nParallel to the defect motion and extension, the entire droplet drifts along\nthe electric field with speed that is independent of the size of the droplet\nand is proportional to the amplitude of the electric field. After the field is\nincreased above 1V/mm the entire droplet gets deformed and oscillates with the\nfield. These observations led us to determine the polarization field and\nrevealed the presence of a pair of positive and negative bound electric charge\ndue to divergences of polarization around the defect volume."
    },
    {
        "anchor": "On the molecular origins of the ferroelectric splay nematic phase: Nematic liquid crystals have been known for more than a century, but it was\nnot until the 60s-70s that, with the development of room temperature nematics,\nthey became widely used in applications. Polar nematic phases have been\nlong-time predicted, but have only been experimentally realized recently.\nSynthesis of materials with nematic polar ordering at room temperature is\ncertainly challenging and requires a deep understanding of its formation\nmechanisms, presently lacking. Here, we compare two materials of similar\nchemical structure and demonstrate that just a subtle change in the molecular\nstructure enables denser packing of the molecules when they exhibit polar\norder, which shows that reduction of excluded volume is in the origin of the\npolar nematic phase. Additionally, we propose that molecular dynamics\nsimulations are potent tools for molecular design in order to predict, identify\nand design materials showing the polar nematic phase and its precursor nematic\nphases.",
        "positive": "Lattice Boltzmann simulations on the role of channel structure for\n  reactive capillary infiltration: It is widely recognized that the structure of porous media is of relevance\nfor a variety of mechanical and physical phenomena. The focus of the present\nwork is on capillarity, a pore-scale process occurring at the micron scale. We\nattempt to characterize the influence of pore shape for capillary infiltration\nby means of Lattice Boltzmann simulations in 2D with reactive boundaries\nleading to surface growth and ultimately to pore closure. The systems under\ninvestigation consist of single channels with different simplified\nmorphologies: namely, periodic profiles with sinusoidal, step-shaped and\nzig-zag walls, as well as constrictions and expansions with rectangular, convex\nand concave steps. This is a useful way to decompose the complexity of typical\nporous media into basic structures. The simulations show that the minimum\nradius alone fails to characterize properly the infiltration dynamics. The\nstructure of the channels emerge as the dominant property controlling the\nprocess. A factor responsible for this behavior is identified as being the\noccurrence of pinning of the contact line. It turns out that the optimal\nconfiguration for the pore structure arises from the packing of large particles\nwith round shapes. In this case, the probability to have flow paths wide and\nstraight is higher. Faceted surfaces presenting sharp edges should be avoided\nbecause of the phenomenon of pinning near narrow-to-wide parts. This study is\nmotivated by the infiltration of molten metals into carbon preforms. This is a\nmanufacturing technique for ceramic components devised to advanced\napplications. Guidelines for experimental work are discussed."
    },
    {
        "anchor": "Charge separation in photosynthesis via a spin exchange coupling\n  mechanism: A new mechanism for the primary photoinduced charge separation in\nphotosynthesis is proposed. It involves as real intermediate between the\nexcited special pair state P* and the primary charge separated state P+HL- a\ntrip-trip-singlet PTBLT, which consists of a triplet on the dimer P and a\nfurther triplet on the monomer BL. Both combine to a singlet. The electron\ntransfer is caused by spin exchange couplings. The transient spectrum of the\nshort lived intermediate, formerly taken as evidence for the charge transfer\nstate P+BL-, is reinterpreted as a transient excitation of this trip-trip\nsinglet.",
        "positive": "Simple Calibration of Block Copolymer Melt Models: According to the universality hypothesis, the phase behavior of different\nblock copolymer melt models having fixed composition depends solely on two\nparameters: the invariant chain length $\\bar{N}$ and the effective interaction\nparameter $\\chi N$. If models behave universally, they can be compared to each\nother and can predict experiment quantitatively. Here, we present a simple way\nto achieve this universality for coarse-grained models. Our method relies on\nthe properties of the monomer interaction potential energy $z$ distribution. In\nparticular, models having near-symmetric $z$-distributions exhibit universal\nphase behavior using the standard linear definition of the Flory-Huggins\nparameter $\\chi\\propto\\alpha$, where $\\alpha =\n\\epsilon_{AB}-(\\epsilon_{AA}+\\epsilon_{BB})/2$, and $\\epsilon_{xy}$ is the\ninteraction energy between monomers of type $x$ and $y$. Previously,\nuniversality had been achieved using a nonlinear $\\chi(\\alpha)$ function which\nis difficult to obtain and interpret physically. The main parameter controlling\nthe symmetry of the $z$-distribution is the monomer density $\\rho$. Above\ncertain $\\rho$, models have symmetric $z$-distributions, and their\norder-disorder transition points follow the universal curve predicted by\nFredrickson-Helfand theory in the experimentally relevant $\\bar{N} > 10^2$\nrange. On the other hand, low-$\\rho$ models exhibit skewed $z$-distributions,\nand the simple $\\chi\\propto\\alpha$ formula is no longer universally applicable\nto them. Our results can be used for correct block copolymer model building\nleading to a simple and direct comparison of simulations to experiments, which\nwill facilitate the screening of new block copolymer morphologies and support\nmaterials design."
    },
    {
        "anchor": "Coupled Aggregation and Sedimentation Processes: Three Dimensional\n  Off-Lattice Simulations: Coupled aggregation and sedimentation processes were studied by means of\nthree dimensional computer simulations. For this purpose, a large prism with no\nperiodic boundary conditions for the sedimentation direction was considered.\nFurthermore, three equally sized and mutually excluded regions were defined\ninside the prism, a top, a middle and a bottom region. This allows to study the\ntime evolution of the cluster size distribution and the cluster structure\nseparately for each region. The mass distribution profile and the center of\nmass position were also accessed as a function of time. For the bottom region,\nthe effects of the sediment formation on the kinetics of growth and on the\ncluster structure were clearly observed. The obtained results not only agree\nwith the experimental data obtained by Allain et. al. and with the simulations\nmade by Gonzalez but also allow to gain further insight in the details.",
        "positive": "Collective Motion of Quincke Rollers with Fully Resolved Hydrodynamics: A Quincke roller is a unique active particle that can run and tumble freely\non a flat plate due to the torque generated by a uniform DC electric field\napplied perpendicular to the plate. A system involving many such particles\nexhibits a variety of collective dynamics, such as the disordered gas, polar\nliquid, and active crystal states. We performed direct numerical simulations of\na three-dimensional system containing many self-rotating particles to\nexplicitly resolve the hydrodynamic interactions among rotating particles. The\ncollective motion depends on the magnitude of the dipole moments induced on the\ndielectric particles, the area fraction of particles, and the strength of\ninterparticle attraction. We find that the highly ordered polar liquid state is\ndestabilized by the hydrodynamic interaction between rotating particles at high\ndensities: the near-field lubrication interaction becomes dominant over\nfar-field effects as the interparticle separation becomes shorter."
    },
    {
        "anchor": "Particles accelerate the detachment of viscous liquids: During detachment of a viscous fluid extruded from a nozzle a filament\nlinking the droplet to the latter is formed. Under the effect of surface\ntension the filament thins until pinch off and final detachment of the droplet.\nIn this paper we study the effect of the presence of individual particles\ntrapped in the filament on the detachment dynamics using granular suspensions\nof small volume fractions ({\\phi} < 6%). We show that even a single particle\nstrongly modifies the detachment dynamics. The particle perturbs the thinning\nof the thread and a large droplet of fluid around the particle is formed. This\nperturbation leads to an acceleration of the detachment of the droplet compared\nto the detachment ob- served for a pure fluid. We quantify this acceleration\nfor single particles of different sizes and link it to similar ob- servations\nfor suspensions of small volume fractions. Our study also gives more insight\ninto particulate effects on de- tachment of more dense suspensions and allows\nto explain the accelerated detachment close to final pinch off observed\npreviously (Bonnoit et al 2012)",
        "positive": "Resummed thermodynamic perturbation theory for bond cooperativity in\n  associating fluids with small bond angles: Effects of steric hindrance and\n  ring formation: In this paper we develop a thermodynamic perturbation theory for two site\nassociating fluids which exhibit bond cooperativity. We include both steric\nhindrance and ring formation such that the equation of state is bond angle\ndependent. Here the bond angle is the angle separating the centers of the two\nassociation sites. As a test, new Monte Carlo simulations are performed, and\nthe theory is found to accurately predict the internal energy as well as the\ndistribution of associated clusters as a function of bond angle and bond\ncooperativity."
    },
    {
        "anchor": "Contact force measurements and local anisotropy in ellipses and disks: Experimental measurements of contact forces are limited to spheres and disks\nin three and two dimensions, making the evaluation of the shape effect and\nuniversality of force distributions and the comparison between experiments and\ntheories extremely difficult. Here we present precise measurements of vector\ncontact forces in photoelastic ellipses and disks subject to isotropic\ncompression and pure shear. We find the local, instead of the global, stress\nratio, control the width of the force distributions for forces larger than the\nmean, regardless of the particle shape and preparation protocols. By taking\nadvantage of the anisotropic particle shape, we can determine the anisotropic\ngrowth of contacts in ellipses subject to isotropic compression, revealing the\nrole of non-affine particle motions in homogenizing force distributions. Our\nresults uncover the role of local anisotropy in the statistical framework of\ngranular materials and open a new regime of exploring the role of particle\nshape on the mechanical and dynamical properties of granular materials in\ndepth.",
        "positive": "Kinetic Capacity of a Protein: The ability of a protein to recognise multiple independent target\nconformations was demonstrated in [1]. Here we consider the recognition of\ncorrelated configurations, which we apply to funnel design for a single\nconformation. The maximum basin of attraction, as parametrised in our model,\ndepends on the number of amino acid species as ln A, independent of protein\nlength. We argue that the extent to which the protein energy landscape can be\nmanipulated is fixed, effecting a trade-off between well breadth, well depth\nand well number. This clarifies the scope and limits of protein and\nheteropolymer function."
    },
    {
        "anchor": "Universal behavior of soft-core fluids near the threshold of\n  thermodynamic stability: We study, by using liquid-state theories and Monte Carlo simulation, the\nbehavior of systems of classical particles interacting through a finite pair\nrepulsion supplemented with a longer range attraction. Any such potential can\nbe driven Ruelle-unstable by increasing the attraction at the expense of\nrepulsion, until the thermodynamic limit is lost. By examining several\npotential forms, we find that all systems exhibit a qualitatively similar\nbehavior in the fluid phase as the threshold of thermodynamic stability is\napproached (and possibly surpassed). The general feature underlying the\napproach to Ruelle instability is a pronounced widening of the liquid-vapor\nbinodal (and spinodal) line at low temperatures, to such an extent that at the\nstability threshold a vanishing-density vapor would coexist with a\ndiverging-density liquid. We attempt to rationalize the universal pathway to\nRuelle instability in soft-core fluids by appealing to a heuristic argument.",
        "positive": "Jamming, Yielding and Rheology of Weakly Vibrated Granular Media: We establish that the rheological curve of dry granular media is\nnon-monotonic, both in the presence and absence of external mechanical\nagitations. In the presence of weak vibrations, the non-monotonic flow curves\ngovern a hysteretic transition between slow but steady and fast, inertial\nflows. In the absence of vibrations, the non-monotonic flow curve governs the\nyielding behavior of granular media. Finally, we show that non-monotonic flow\ncurves can be seen in at least two different flow geometries and for several\ngranular materials."
    },
    {
        "anchor": "Magnetic Levitation Stabilized by Streaming Fluid Flows: We demonstrate that the ubiquitous laboratory magnetic stirrer provides a\nsimple passive method of magnetic levitation, in which the so-called `flea'\nlevitates indefinitely. We study the onset of levitation and quantify the\nflea's motion (a combination of vertical oscillation, spinning and \"waggling\"),\nfinding excellent agreement with a mechanical analytical model. The waggling\nmotion drives recirculating flow, producing a centripetal reaction force that\nstabilises the flea. Our findings have implications for the locomotion of\nartificial swimmers, for the development of bidirectional microfluidic pumps\nand provide an alternative to sophisticated commercial levitators.",
        "positive": "Mechanics of nematic membranes: Euler-Lagrange equations, Noether\n  charges, stress, torque and boundary conditions of the surface Frank nematic\n  field: The mechanics of a flexible membrane decorated with a nematic liquid-crystal\ntexture is considered in a variational framework. The variations on the splay,\ntwist and the bend energy of the nematics are obtained from the local\ndeformations leading to changes in the shape membrane. The Euler-Lagrange\nderivatives and the Noether charges are identified from the variational\nequations. The nematic stress tensor is obtained as a consequence of\ntranslational invariance. Likewise, the rotational invariance implies the\ntorque nematic tensor. The corresponding boundary conditions are obtained for\nfree edges in the open-membrane configuration. These results constitute the\nbasis of a generalized theory of elasticity for anisotropic nematic membranes.\nSome relevant consequences of the presence of nematic ordering are visualized\nat revolution surfaces with axial symmetry."
    },
    {
        "anchor": "Splitting droplet through coalescence of two different three-phase\n  contact lines: Moving contact lines of more than two phases dictate a large number of\ninterfacial phenomena. Despite its significance to fundamental and applied\nprocesses, the contact lines at a junction of four-phases (two immiscible\nliquids, solid and gas) have been addressed only in a few investigations. Here,\nwe report an intriguing phenomenon that follows after the four phases of oil,\nwater, solid and gas make contact through the coalescence of two different\nthree-phase contact lines. We combine experimental study and theoretical\nanalysis to reveal and rationalize the dynamics exhibited upon the coalescence\nbetween the contact line of a micron-sized oil droplet and the receding contact\nline of a millimetre-sized water drop that covers the oil droplet on the\nsubstrate. We find that after the coalescence a four-phase contact line is\nformed for a brief period. However, this quadruple contact line is not stable,\nleading to a `droplet splitting' effect and eventual expulsion of the oil\ndroplet from the water drop. We then show that the interfacial tension between\nthe different phases and the viscosity of oil droplet dictate the splitting\ndynamics. More viscous oils display higher resistance to the extreme\ndeformations of the droplet induced by the instability of the quadruple contact\nline and no droplet expulsion is observed for such cases.",
        "positive": "Coalescence of Drops Near A Hydrophilic Boundary Leads to Long Range\n  Directed Motion: A new mechanism for the passive removal of drop on a horizontal surface is\ndescribed that does not require pre-fabrication of a surface energy gradient.\nThe method relies upon the preparation of alternate hydrophilic/hydrophobic\nstripes on a surface. When one side of this surface is exposed to steam, with\nits other surface convectively cooled with cold water, steam condenses as a\ncontinuous film on the hydrophilic stripes but as droplets on the hydrophobic\nstripes. Coalescence leads to a random motion of the center of mass of the\nfused drops on the surface, which are readily removed as they reach near the\nboundary of the hydrophobic and hydrophilic zones thus resulting in a net\ndiffusive flux of the coalesced drops from the hydrophobic to the hydrophilic\nstripes of the surface. Although an in-situ produced thermal gradient due to\ndifferential heat transfer coefficients of the hydrophilic and hydrophobic\nstripes could provide additional driving force for such a motion, it is,\nhowever, not a necessary condition for motion to occur. This method of creating\ndirected motion of drops does not require a pre-existing wettability gradient\nand may have useful applications in thermal management devices."
    },
    {
        "anchor": "Anisotropy of shear relaxation in primitive chain network simulations\n  for entangled polymers confined between flat walls: Anisotropic shear relaxation is an interesting but rarely discussed issue in\npolymer dynamics under confinement [Abberton et al., Macromolecules, 48, 7631,\n2015]. According to the earlier study of bead spring simulations for an\nunentangled polymer melt confined between two flat plates, the shear relaxation\nmodulus taken perpendicular to the interface is accelerated by decreasing the\ndistance between plates, whereas the parallel component is unchanged. This\nstudy observed similar anisotropic shear relaxation for entangled polymer melts\nunder confinement in multi-chain slip-link simulations (primitive chain network\nsimulations). The analysis demonstrated that the accelerated relaxation in the\nperpendicular component reflects the Rouse-type constraint release dynamics,\nfor which the coarsening is upper-limited by the geometry. This result suggests\na novel mechanism for anisotropic shear relaxation different from the modified\nchain statistics under confinement considered for unentangled systems.",
        "positive": "Universal reshaping of arrested colloidal gels via active doping: Colloids that interact via a short-range attraction serve as the primary\nbuilding blocks for a broad range of self-assembled materials. However, one of\nthe well-known drawbacks to this strategy is that these building blocks rapidly\nand readily condense into a metastable colloidal gel. Using computer\nsimulations, we illustrate how the addition of a small fraction of purely\nrepulsive self-propelled colloids, a technique referred to as active doping,\ncan prevent the formation of this metastable gel state and drive the system\ntoward its thermodynamically favored crystalline target structure. The\nsimplicity and robust nature of this strategy offers a systematic and generic\npathway to improving the self-assembly of a large number of complex colloidal\nstructures. We discuss in detail the process by which this feat is accomplished\nand provide quantitative metrics for exploiting it to modulate self-assembly.\nWe provide evidence for the generic nature of this approach by demonstrating\nthat it remains robust under a number of different anisotropic short-ranged\npair interactions in both two and three dimensions. In addition, we report on a\nnovel microphase in mixtures of passive and active colloids. For a broad range\nof self-propelling velocities, it is possible to stabilize a suspension of\nfairly monodisperse finite-size crystallites. Surprisingly, this microphase is\nalso insensitive to the underlying pair interaction between building blocks.\nThe active stabilization of these moderately-sized monodisperse clusters is\nquite remarkable and should be of great utility in the design of hierarchical\nself-assembly strategies. This work further bolsters the notion that active\nforces can play a pivotal role in directing colloidal self-assembly."
    },
    {
        "anchor": "Adsorption desorption processes on mesoscopic pores conected to\n  microscopic pores of complex geometry using the Ising model: In this work we report studies of nitrogen adsorption and desorption onto\nsolid surfaces using computer simulations of the three dimensional Ising model,\nfor systems with complex porous structures at the mesoscopic and microscopic\nlevels. A hysteresis cycle between the adsorption and desorption processes\nappears and we find that its characteristics are dependent on the geometry of\nthe pore and on the strength of the surface fluid interaction. We obtained also\nan average adsorption isotherm, which represents a combination of differently\nshaped pores, and shows robust jumps at certain values of the chemical\npotential as a consequence of the structures of the pores. Lastly, we compare\nour results with experimental data and also report the filling process of\nmicroscopic pores connected with mesopores. It is argued that these predictions\nare useful for researchers working on the enhanced recovery of oil and for the\ndesign of new nanomaterials, among others.",
        "positive": "Gliders in shape-changing active matter: We report in experiment and simulation the spontaneous formation of\ndynamically bound pairs of shape changing smarticle robots undergoing locally\nrepulsive collisions. Borrowing terminology from Conway's simulated Game of\nLife, these physical `gliders' robustly emerge from an ensemble of individually\nundulating three-link two-motor smarticles and can remain bound for hundreds of\nundulations and travel for multiple robot dimensions. Gliders occur in two\ndistinct binding symmetries and form over a wide range of angular flapping\nextent. This parameter sets the maximal concavity which influences formation\nprobability and translation characteristics. Analysis of dynamics in simulation\nreveals the mechanism of effective dynamical attraction -- a result of the\nemergent interplay of appropriately oriented and timed repulsive interactions."
    },
    {
        "anchor": "Elasticity Theory of a Twisted Stack of Plates: We present an elastic model of B-form DNA as a stack of thin, rigid plates or\nbase pairs that are not permitted to deform. The symmetry of DNA and the\nconstraint of plate rigidity limit the number of bulk elastic constants\ncontributing to a macroscopic elasticity theory of DNA to four. We derive an\neffective twist-stretch energy in terms of the macroscopic stretch epsilon\nalong and relative excess twist sigma about the DNA molecular axis. In addition\nto the bulk stretch and twist moduli found previously, we obtain a\ntwist-stretch modulus with the following remarkable properties: 1) it vanishes\nwhen the radius of the helical curve following the geometric center of each\nplate is zero, 2) it vanishes with the elastic constant K_{23} that couples\ncompression normal to the plates to a shear strain, if the plates are\nperpendicular to the molecular axis, and 3) it is nonzero if the plates are\ntilted relative to the molecular axis. This implies that a laminated helical\nstructure carved out of an isotropic elastic medium will not twist in response\nto a stretching force, but an isotropic material will twist if it is bent into\nthe shape of a helix.",
        "positive": "On measuring the acoustic state changes in lipid membranes using\n  fluorescent probes: Ultrasound is increasingly being used to modulate the properties of\nbiological membranes for applications in drug delivery and neuromodulation.\nWhile various studies have investigated the mechanical aspect of the\ninteraction such as acoustic absorption and membrane deformation, it is not\nclear how these effects transduce into biological functions, for example,\nchanges in the permeability or the enzymatic activity of the membrane. A\ncritical aspect of the activity of an enzyme is the thermal fluctuations of its\nsolvation or hydration shell. Thermal fluctuations are also known to be\ndirectly related to membrane permeability. Here solvation shell changes of\nlipid membranes subject to an acoustic impulse were investigated using a\nfluorescence probe, Laurdan. Laurdan was embedded in multi-lamellar lipid\nvesicles in water, which were exposed to broadband pressure impulses of the\norder of 1MPa peak amplitude and 10{\\mu}s pulse duration. An instrument was\ndeveloped to monitor changes in the emission spectrum of the dye at two\nwavelengths with sub-microsecond temporal resolution. The experiments show that\nchanges in the emission spectrum, and hence the fluctuations of the solvation\nshell, are related to the changes in the thermodynamic state of the membrane\nand correlated with the compression and rarefaction of the incident sound wave.\nThe results suggest that acoustic fields affect the state of a lipid membrane\nand therefore can potentially modulate the kinetics of channels and proteins\nembedded in the membrane."
    },
    {
        "anchor": "Size-Stretched Exponential Relaxation in a Model with Arrested States: We study the effect of rapid quench to zero temperature in a model with\ncompeting interactions, evolving through conserved spin dynamics. In a certain\nregime of model parameters, we find that the model belongs to the broader class\nof kinetically constrained models, however, the dynamics is different from that\nof a glass. The system shows stretched exponential relaxation with the unusual\nfeature that the relaxation time diverges as a power of the system size.\nExplicitly, we find that the spatial correlation function decays as\n$\\exp(-2r/\\sqrt{L})$ as a function of spatial separation $r$ in a system with\n$L$ sites in steady state, while the temporal auto-correlation function follows\n$\\exp(-(t/\\tau_L)^{1/2})$, where $t$ is the time and $\\tau_L$ proportional to\n$L$. In the coarsening regime, after time $t_w$, there are two growing length\nscales, namely $\\mathcal{L}(t_w) \\sim t_w^{1/2}$ and $\\mathcal{R}(t_w) \\sim\nt_w^{1/4}$; the spatial correlation function decays as $\\exp(-r/\n\\mathcal{R}(t_w))$. Interestingly, the stretched exponential form of the\nauto-correlation function of a single typical sample in steady state differs\nmarkedly from that averaged over an ensemble of initial conditions resulting\nfrom different quenches; the latter shows a slow power law decay at large\ntimes.",
        "positive": "Inertial hydrodynamic ratchet: Rectification of colloidal flow in tubes\n  of variable diameter: We investigate analytically a microfluidic device consisting of a tube with\nnon-uniform but spatially periodic diameter, where a fluid driven back and\nforth by a pump carries colloidal particles. Although the net flow of the fluid\nis zero, the particles move preferentially in one direction due to ratchet\nmechanism, which occurs by simultaneous effect of inertial hydrodynamics and\nBrownian motion. We show that the average current is strongly sensitive to\nparticle size, thus facilitating colloidal particle sorting."
    },
    {
        "anchor": "Light-induced switching in the back-gated organic transistors with\n  built-in conduction channel: We report on observation of a light-induced switching of the conductance in\nthe back-gated organic field-effect transistors (OFETs) with built-in\nconduction channel. In the studied devices, the built-in channel is formed\nowing to the self-sensitized photo-oxidation of rubrene surface. In the dark,\nthe back gate controls the charge injection from metal contacts into the\nbuilt-in channel: the high-current ON state corresponds to zero or negative\nback-gate voltage; the low-current OFF state - to a positive back-gate voltage\nthat blocks the Schottky contacts. Illumination of the OFET in the OFF state\nwith a short pulse of light switches the device into the ON state that persists\nin the dark for days. The OFF state can be restored by cycling the back gate\nvoltage. The observed effect can be explained by screening of the back-gate\nelectric field by the charges photo-generated in the bulk of organic\nsemiconductor.",
        "positive": "Polyelectrolyte Persistence Length: Attractive Effect of Counterion\n  Correlations and Fluctuations: The persistence length of a single, strongly charged, stiff polyelectrolyte\nchain is investigated theoretically. Path integral formulation is used to\nobtain the effective electrostatic interaction between the monomers. We find\nsignificant deviations from the classical Odijk, Skolnick and Fixman (OSF)\nresult. An induced attraction between monomers is due to thermal fluctuations\nand correlations between bound counterions. The electrostatic persistence\nlength is found to be smaller than the OSF value and indicates a possible\nmechanical instability (collapse) for highly charged polyelectrolytes with\nmultivalent counterions. In addition, we calculate the amount of condensed\ncounterions on a slightly bent polyelectrolyte. More counterions are found to\nbe adsorbed as compared to the Manning condensation on a cylinder."
    },
    {
        "anchor": "Energy-landscape network approach to the glass transition: We study the energy-landscape network of Lennard-Jones clusters as a model of\na glass forming system. We find the stable basins and the first order saddles\nconnecting them, and identify them with the network nodes and links,\nrespectively. We analyze the network properties and model the system's\nevolution. Using the model, we explore the system's response to varying cooling\nrates, and reproduce many of the glass transition properties. We also find that\nthe static network structure gives rise to a critical temperature where a\npercolation transition breaks down the space of configurations into\ndisconnected components. Finally, we discuss the possibility of studying the\nsystem mathematically with a trap-model generalized to networks.",
        "positive": "Activity Induced Diffusion Recovery in Crowded Colloidal Suspension: We show that the force generated by active enzyme molecules are strong enough\nto influence the dynamics of their surroundings under artificial crowded\nenvironments. We measured the behavior of polymer microparticles in a\nquasi-two-dimensional system under aqueous environment, at various area\nfraction values of particles. In the presence of enzymatic activity not only\nthe diffusion of the suspended particles at shorter time-scale regime enhanced,\nthe system also showed a transition from sub-diffusive to diffusive dynamics at\nlonger time-scale limits. Similar observations were also recorded with enzyme\nfunctionalized microparticles. Brownian dynamics simulations have been\nperformed to support the experimental observations."
    },
    {
        "anchor": "Sliding grafted polymer layers: We study theoretically the structure of sliding grafted polymer layers or SGP\nlayers. These interfacial structures are built by attaching each polymer to the\nsubstrate with a ring-like molecule such as cyclodextrins. Such a topological\ngrafting mode allows the chains to freely slide along the attachment point.\nEscape from the sliding link is prevented by bulky capping groups. We show that\ngrafts in the mushroom regime adopt mainly symmetric configurations (with\ncomparable branch sizes) while grafts in dense layers are highly dissymmetric\nso that only one branch per graft participates in the layer. Sliding layers on\nsmall colloids or star-like sliding micelles exhibit an intermediate behavior\nwhere the number of longer branches participating in the corona is independent\nof the total number of branches. This regime also exists for sliding\nsurface-micelles comprising less chains but it is narrower.",
        "positive": "Colloidal suspensions in modulated light fields: Periodically-modulated potentials in the form of light fields have previously\nbeen applied to induce reversible phase transitions in dilute colloidal systems\nwith long-range interactions. Here we investigate whether similar transitions\ncan be induced in very dense systems, where inter-particle contacts are\nimportant. Using microscopy we show that particles in such systems are indeed\nstrongly affected by modulated potentials. We discuss technical aspects\nrelevant to generating the light-induced potentials and to imaging\nsimultaneously the particles. We also consider what happens when the particle\nsize is comparable with the modulation wavelength. The effects of selected\nmodulation wavelengths as well as pure radiation pressure are illustrated."
    },
    {
        "anchor": "Side branched patterns, coalescence and stable interfaces during radial\n  displacement of a viscoelastic fluid: We explore the interfacial instability that results when a Newtonian fluid (a\nglycerol-water mixture, inner fluid) displaces a viscoelastic fluid (a dense\ncornstarch suspension, outer fluid) in a radial Hele-Shaw cell. As the ratio of\nviscosities of the inner and outer fluids is increased, side branched\ninterfacial patterns are replaced by more stable interfaces that display\nproportionate growth and finger coalescence. We correlate the average finger\nspacing with the most dominant wavelength of interfacial instability, computed\nusing a mathematical model that accounts for viscous fingering in miscible\nHele-Shaw displacements. The model predictions on the role of viscosity ratio\non finger spacing are in close agreement with the experimental observations.\nOur study lends insight into the significant contribution of the\nviscoelasticity of the outer fluid on the morphology and growth of interfacial\npatterns.",
        "positive": "Sound attenuation in finite-temperature stable glasses: The temperature dependence of the thermal conductivity of amorphous solids is\nmarkedly different from that of their crystalline counterparts, but exhibits\nuniversal behaviour. Sound attenuation is believed to be related to this\nuniversal behaviour. Recent computer simulations demonstrated that in the\nharmonic approximation sound attenuation $\\Gamma$ obeys quartic, Rayleigh\nscattering scaling for small wavevectors $k$ and quadratic scaling for\nwavevectors above the Ioffe-Regel limit. However, simulations and experiments\ndo not provide a clear picture of what to expect at finite temperatures where\nanharmonic effects become relevant. Here we study sound attenuation at finite\ntemperatures for model glasses of various stability, from unstable glasses that\nexhibit rapid aging to glasses whose stability is equal to those created in\nlaboratory experiments. We find several scaling laws depending on the\ntemperature and stability of the glass. First, we find the large wavevector\nquadratic scaling to be unchanged at all temperatures. Second, we find that at\nsmall wavectors $\\Gamma \\sim k^{1.5}$ for an aging glass, but $\\Gamma \\sim k^2$\nwhen the glass does not age on the timescale of the calculation. For our most\nstable glass, we find that $\\Gamma \\sim k^2$ at small wavevectors, then a\ncrossover to Rayleigh scattering scaling $\\Gamma \\sim k^4$, followed by another\ncrossover to the quadratic scaling at large wavevectors. Our computational\nobservation of this quadratic behavior reconciles simulation, theory and\nexperiment, and will advance the understanding of the temperature dependence of\nthermal conductivity of glasses."
    },
    {
        "anchor": "Closure Relations for Shallow Granular Flows from Particle Simulations: The Discrete Particle Method (DPM) is used to model granular flows down an\ninclined chute. We observe three major regimes: static piles, steady uniform\nflows and accelerating flows. For flows over a smooth base, other\n(quasi-steady) regimes are observed where the flow is either highly energetic\nand strongly layered in depth for small inclinations, or non-uniform and\noscillating for larger inclinations.\n  For steady uniform flows, depth profiles of density, velocity and stress have\nbeen obtained using an improved coarse-graining method, which allows accurate\nstatistics even at the base of the flow. A shallow-layer model for granular\nflows is completed with macro-scale closure relations obtained from micro-scale\nDPM simulations of steady flows. We thus obtain relations for the effective\nbasal friction, shape factor, mean density, and the normal stress anisotropy as\nfunctions of layer thickness, flow velocity and basal roughness. For\ncollisional flows, the functional dependencies are well determined and have\nbeen obtained.",
        "positive": "Fluctuations of red blood cell membranes: The role of cytoskeleton: We theoretically investigate the membrane fluctuations of red blood cells\nwith focus laid on the role of the cytoskeleton, viewing the system as a\nmembrane coupled to sparse spring network. This model is exactly solvable and\nenables us to examine the coupling strength dependence of the membrane\nundulation. We find that the coupling modifies the fluctuation spectrum at\nwavelengths longer than the mesh size of the network, while leaving the\nfluid-like behavior of the membrane intact at shorter wavelengths. The\nfluctuation spectra can be markedly different, depending on not only the\nrelative amplitude of the bilayer bending energy with respect to the\ncytoskeleton deformation energy but also the bilayer-cytoskelton coupling\nstrength."
    },
    {
        "anchor": "Local Elasticity in Nonlinear Rheology of Interacting Colloidal Glasses\n  Revealed by Neutron Scattering and Rheometry: The flow of colloidal suspensions is ubiquitous in nature and industry.\nColloidal suspensions exhibit a wide range of rheological behavior, which\nshould be closely related to the microscopic structure of the systems. With\nin-situ small-angle neutron scattering complemented by rheological\nmeasurements, we investigated the deformation behavior of a charge-stabilized\ncolloidal glass at particle level undergoing steady shear. A short-lived,\nlocalized elastic response at particle level, termed as transient elasticity\nzone (TEZ), was identified from the neutron spectra. The existence of the TEZ\nis a signature of the dynamical heterogeneity: The body of fluids under shear\nbehaves like an elastic solid within the spatial range of TEZ but like fluid\noutside the TEZ. The size of TEZ shrinks as the shear rate increases in the\nshear thinning region, which shows that the shear thinning is accompanied by a\ndiminishing dynamical heterogeneity. More interestingly, the TEZ is found to be\nthe structural unit that provides the resistance to the imposed shear, as\nevidenced by the quantitative agreement between the local elastic stress\nsustained by TEZ and the macroscopic stress from rheological measurements at\nlow and moderate shear rates. Besides the charged-stabilized colloidal\nsuspension, a hard-sphere colloidal suspension at the same volume fraction and\nshear rates was also measured. The result highlights the key role of the\nelectrostatic interparticle repulsion in promoting the local elasticity. Our\nfindings provide an understanding on the nonlinear rheology of interacting\ncolloidal glasses from a micro-mechanical view.",
        "positive": "Reconnection and acoustic emission of quantized vortices in superfluid\n  by the numerical analysis of the Gross-Pitaevskii equation: We study numerically the reconnection of quantized vortices and the\nconcurrent acoustic emission by the analysis of the Gross-Pitaevskii equation.\nTwo quantized vortices reconnect following the process similar to classical\nvortices; they approach, twist themselves locally so that they become\nanti-parallel at the closest place, reconnect and leave separately.The\ninvestigation of the motion of the singular lines where the amplitude of the\nwave function vanishes in the vortex cores confirms that they follow the above\nscenario by reconnecting at a point. This reconnection is not contradictory to\nthe Kelvin's circulation theorem, because the potential of the superflow field\nbecomes undefined at the reconnection point. When the locally anti-parallel\npart of the vortices becomes closer than the healing length, it moves with the\nvelocity comparable to the sound velocity, emits the sound waves and leads to\nthe pair annihilation or reconnection; this phenomena is concerned with the\nCherenkov resonance. The vortices are broken up to smaller vortex loops through\na series of reconnection, eventually disappearing with the acoustic emission.\nThis may correspond to the final stage of the vortex cascade process proposed\nby Feynman. The change in energy components, such as the quantum, the\ncompressible and incompressible kinetic energy is analyzed for each dynamics.\nThe propagation of the sound waves not only appears in the profile of the\namplitude of the wave function but also affects the field of its phase,\ntransforming the quantum energy due to the vortex cores to the kinetic energy\nof the phase field."
    },
    {
        "anchor": "Sublinear drag regime at mesoscopic scales in viscoelastic materials: Stressed soft materials commonly present viscoelastic signatures in the form\nof power-law or exponential decay. Understanding the origins of such rheologic\nbehaviors is crucial to find proper technological applications. Using an\nelastic network model of macromolecules immersed in a viscous fluid, we\nnumerically reproduce those characteristic viscoelastic relaxations and show\nhow the microscopic interactions determine the rheologic response. We find that\nexponential relaxations are indeed the most common behavior. However, power\nlaws may arise when drag forces between the macromolecules and the fluid are\nsublinear, which is related to micro-deformations of the macromolecules.",
        "positive": "Nematic phase transitions in mixtures of thin and thick colloidal rods: We present the first experimental measurements of the isotropic and nematic\nphases of mixtures of thin, charged semiflexible fd virus, and thick, fd-PEG\ncreated by covalently grafting poly-(ethylene glycol) to the the surface of fd,\nrods. The fd-PEG is sterically stabilized and its phase behavior is independent\nof ionic strength. The fd is charged. Therefore, by varying the ionic strength\nof a mixture of fd and fd-PEG, only the effective diameter of the bare fd rods\nchanges, subsequently varying the effective diameter ratio (d=D_fd-PEG/D_fd)\nfrom 3.7 to 1. In solution, binary mixtures of fd and fd-PEG are shown to\nexhibit isotropic-nematic, isotropic-nematic-nematic and nematic-nematic\ncoexisting phases with increasing concentration. We measure the binary phase\ndiagrams as a function of composition, total concentration, and ionic strength.\nWe find a lower critical point in the nematic-nematic coexistence region which\nhas not been observed previously. These experimental results resolve a\ncontroversy in the literature concerning the evolution of the nematic-nematic\nphase separation with concentration. The experimental results are qualitatively\ndescribed by a rescaled Onsager-type theory for the phase behavior of binary\nrod mixtures."
    },
    {
        "anchor": "Simulations of DNA-origami self-assembly reveal design-dependent\n  nucleation barriers: Nucleation is the rate-determining step in the kinetics of many self-assembly\nprocesses. However, the importance of nucleation in the kinetics of DNA-origami\nself-assembly, which involves both the binding of staple strands and the\nfolding of the scaffold strand, is unclear. Here, using Monte Carlo simulations\nof a lattice model of DNA origami, we find that some, but not all, designs can\nhave a nucleation barrier and that this barrier disappears at lower\ntemperatures, rationalizing the success of isothermal assembly. We show that\nthe height of the nucleation barrier depends primarily on the coaxial stacking\nof staples that are adjacent on the same helix, a parameter that can be\nmodified with staple design. Creating a nucleation barrier to DNA-origami\nassembly could be useful in optimizing assembly times and yields, while\neliminating the barrier may allow for fast molecular sensors that can\nassemble/disassemble without hysteresis in response to changes in the\nenvironment.",
        "positive": "Glassy Dynamics in Chiral Fluids: Chiral active matter is enjoying a rapid increase of interest, spurred by the\nrich variety of asymmetries that can be attained in e.g. the shape or\nself-propulsion mechanism of active particles. Though this has already led to\nthe observance of so-called chiral crystals, active chiral glasses remain\nlargely unexplored. A possible reason for this could be the naive expectation\nthat interactions dominate the glassy dynamics and the details of the active\nmotion become increasingly less relevant. Here we show that quite the opposite\nis true by studying the glassy dynamics of interacting chiral active Brownian\nparticles (cABPs). We demonstrate that when our chiral fluid is pushed to\nglassy conditions, it exhibits highly nontrivial dynamics, especially compared\nto a standard linear active fluid such as common ABPs. Despite the added\ncomplexity, we are still able to present a full rationalization for all\nidentified dynamical regimes. Most notably, we introduce a new 'hammering'\nmechanism, unique to rapidly spinning particles in high-density conditions,\nthat can fluidize a chiral active solid."
    },
    {
        "anchor": "Euclidean Frustrated Ribbons: Geometrical frustration in thin sheets is ubiquitous across scales in biology\nand becomes increasingly relevant in technology. Previous research identified\nthe origin of the frustration as the violation of Gauss's \\emph{Theorema\nEgregium}. Such \"Gauss frustration\" exhibits rich phenomenology; it may lead to\nmechanical instabilities, anomalous mechanics and shape-morphing abilities that\ncan be harnessed in engineering systems. Here we report a new type of\ngeometrical frustration, one that is as general as Gauss frustration. We show\nthat its origin is the violation of Mainardi-Codazzi-Peterson compatibility\nequations and that it appears in Euclidean sheets. Combining experiments,\nsimulations and theory, we study the specific case of a Euclidean ribbon with\nradial and geodesic curvatures. Experiments, conducted using different\nmaterials and techniques, reveal shape transitions, symmetry breaking and\nspontaneous stress focusing. These observations are quantitatively rationalized\nusing analytic solutions and geometrical arguments. We expect this frustration\nto play a significant role in natural and engineering systems, specifically in\nslender 3D printed sheets.",
        "positive": "Spontaneous rectification and absolute negative mobility of inertial\n  Brownian particles induced by Gaussian potentials in steady laminar flows: We study the transport of inertial Brownian particles in steady laminar flows\nin the presence of two-dimensional Gaussian potentials. Through extensive\nnumerical simulations, it is found that the transport is sensitively dependent\non the external constant force and the Gaussian potential. Within tailored\nparameter regimes, the system exhibits a rich variety of transport behaviors.\nIn the absence of any external driving forces, the spontaneous rectification of\nthe particles can be manipulated by the spatial position of the Gaussian\npotential. Moreover, when the potential lies at the center of the cellular\nflow, the system exhibits absolute negative mobility (ANM), i.e., the particles\ncan move in a direction opposite to the constant force. More importantly, the\nphenomenon of ANM induced by Gaussian potential is robust in a wider range of\nthe system parameters and can be further strengthened with the optimized\nparameters, which may pave the way to the implementation of related\nexperiments."
    },
    {
        "anchor": "Anisotropic imbibition on surfaces patterned with polygonal posts: We present and interpret lattice Boltzmann simulations of thick films\nspreading on surfaces patterned with polygonal posts. We show that the\nmechanism of pinning and depinning differs with the direction of advance, and\ndemonstrate that this leads to anisotropic spreading within a certain range of\nmaterial contact angles.",
        "positive": "Modeling the Behavior of Confined Colloidal Particles Under Shear Flow: We investigate the behavior of colloidal suspensions with different volume\nfractions confined between parallel walls under a range of steady shears. We\nmodel the particles using molecular dynamics (MD) with full hydrodynamic\ninteractions implemented through the use of a lattice-Boltzmann (LB) fluid. A\nquasi-2d ordering occurs in systems characterized by a coexistence of coupled\nlayers with different densities, order, and granular temperature. We present a\nphase diagram in terms of shear and volume fraction for each layer, and\ndemonstrate that particle exchange between layers is required for entering the\ndisordered phase."
    },
    {
        "anchor": "Symmetry properties of nonlinear hydrodynamic interactions between\n  responsive particles: Two identical particles driven by the same steady force through a viscous\nfluid may move relative to one another due to hydrodynamic interactions. The\npresence or absence of this relative translation has a profound effect on the\ndynamics of a driven suspension consisting of many particles. We consider a\npair of particles which, to linear order in the force, do not interact\nhydrodynamically. If the system possesses an intrinsic property (such as the\nshape of the particles, their position with respect to a boundary, or the shape\nof the boundary) which is affected by the external forcing, hydrodynamic\ninteractions that depend nonlinearly on the force may emerge. We study the\ngeneral properties of such nonlinear response. Analysis of the symmetries under\nparticle exchange and under force reversal leads to general conclusions\nconcerning the appearance of relative translation and the motion's\ntime-reversibility. We demonstrate the applicability of the conclusions in\nthree specific examples: (a) two spheres driven parallel to a wall; (b) two\ndeformable objects driven parallel to their connecting line; and (c) two\nspheres driven along a curved path. The breaking of time-reversibility suggests\na possible use of nonlinear hydrodynamic interactions to disperse or assemble\nparticles by an alternating force.",
        "positive": "Generalized Master Equation with Two Times: Diffusion in External Field: The generalized master equation with two times, introduced in earlier,\napplies to the problem of diffusion in an time-dependent (in general\ninhomogeneous) external field. We consider the case of the quasi Fokker-Planck\napproximation, when the probability transition function for diffusion\n(PTD-function) does not possess a long tail in coordinate space and can be\nexpanded as the function of instantaneous displacements. The more complicated\ncase of the long tails in PTD will be discussed separately."
    },
    {
        "anchor": "Interplay of pH and Binding of Multivalent Metal Ions: Charge Inversion\n  and Reentrant Condensation in Protein Solutions: Tuning of protein surface charge is a fundamental mechanism in biological\nsystems. Protein charge is regulated in a physiological context by pH and\ninteraction with counterions. We report on charge inversion and the related\nreentrant condensation in solutions of globular proteins with different\nmultivalent metal cations. In particular, we focus on the changes in phase\nbehavior and charge regulation due to pH effects caused by hydrolysis of metal\nions. For several proteins and metal salts, charge inversion as measured by\nelectrophoretic light scattering is found to be a universal phenomenon, the\nextent of which is dependent on the specific protein-salt combination.\nReentrant phase diagrams show a much narrower phase-separated regime for acidic\nsalts such as AlCl3 and FeCl3 compared to neutral salts such as YCl3 or LaCl3 .\nThe differences between acidic and neutral salts can be explained by the\ninterplay of pH effects and binding of the multivalent counterions. The\nexperimental findings are reproduced with good agreement by an analytical model\nfor protein charging taking into account ion condensation, metal ion hydrolysis\nand interaction with charged amino acid side chains on the protein surface.\nFinally, the relationship of charge inversion and reentrant condensation is\ndiscussed, suggesting that pH variation in combination with multivalent cations\nprovides control over both attractive and repulsive interactions between\nproteins.",
        "positive": "Athermal Jamming vs. glassy dynamics for particles with exponentially\n  decaying repulsive pair interaction potentials with a cutoff: We study athermal jamming as well as the thermal glassy dynamics in systems\ncomposed of spheres that interact according to repulsive interactions that\nexponentially decay as a function of distance. As usual, a cutoff is employed\nin the simulations. While the athermal jamming transition that is determined by\ntrying to remove overlaps is found to depend on the arbitrary and therefore\nunphysical choice of the cutoff, we do not find any athermal jamming transition\nor crossover that only relies on the physical decay length. In contrast, the\nglassy dynamics mainly depends on the decay length. Our findings constitute\nanother demonstration of the fact that the athermal jamming transition is not\nrelated to thermal glassy dynamics. In addition, we argue that interactions\nwithout sharp physical cutoff should be considered more often as a model system\nin jamming. By exploring how widely-used theoretical approaches or methods of\nanalysis in the field of jamming have to be changed in order to not depend on\nunphysical cutoffs will lead to deeper insights into the nature of athermal and\nthermal jamming."
    },
    {
        "anchor": "Bacterial chromosome organization I: crucial role of release of\n  topological constraints and molecular crowders: We showed in our previous studies that just $3\\%$ cross-links, at special\npoints along the contour of the bacterial DNA help the DNA-polymer to get\norganized at micron length scales \\cite{jpcm,epl}.\n  In this work, we investigate how does the release of topological constraints\nhelp in the organization of the DNA-polymer. Furthermore, we show that the\nchain compaction induced by the crowded environment in the bacterial cytoplasm\ncontributes to the organization of the DNA-polymer. We model the DNA chain as a\nflexible bead-spring ring polymer, where each bead represents $1000$ base\npairs. The specific positions of the cross-links have been taken from the\nexperimental contact maps of the bacteria {\\em C. crescentus} and {\\em E.\ncoli}. We introduce different extents of topological constraints in our model\nby systematically changing the diameter of the monomer bead. It varies from the\nvalue where the chain crossing can occur freely to the value where the chain\ncrossing is disallowed. We also study the role of molecular crowders by\nintroducing an effective Lennard Jones attraction between the monomers. Using\nMonte-Carlo simulations, we show that the release of topological constraints\nand the crowding environment play a crucial role to obtain a unique\norganization of the polymer.",
        "positive": "Rotational sound in disordered granular materials: We employ numerical simulations to understand the evolution of elastic\nstanding waves in disordered frictional disk systems, where the dispersion\nrelations of rotational sound modes are analyzed in detail. As in the case of\nfrictional particles on a lattice, the rotational modes exhibit an\n\"optical-like\" dispersion relation in the high frequency regime, representing a\nshoulder of the vibrational density of states and fast oscillations of the\nautocorrelations of rotational velocities. A lattice-based model describes the\ndispersion relations of the rotational modes for small wave numbers. The\nrotational modes are perfectly explained by the model if tangential elastic\nforces between the disks in contact are large enough. If the tangential forces\nare comparable with or smaller than normal forces, the model fails for short\nwave lengths. However, the dispersion relation of the rotational modes then\nfollows the model prediction for transverse modes, implying that the fast\noscillations of disks' rotations switch to acoustic sound behavior. We evidence\nsuch a transition of the rotational modes by analyzing the eigen vectors of\ndisordered frictional disks and identify upper and lower limits of the\nfrequency-bands. We find that those are not reversed over the whole range of\ntangential stiffness as a remarkable difference from the rotational sound in\nfrictional particles on a lattice."
    },
    {
        "anchor": "Phase Transitions in Hexane Monolayers Physisorbed onto Graphite: We report the results of molecular dynamics (MD) simulations of a complete\nmonolayer of hexane physisorbed onto the basal plane of graphite. At low\ntemperatures the system forms a herringbone solid. With increasing temperature,\na solid to nematic liquid crystal transition takes place at $T_1 = 138 \\pm 2$K\nfollowed by another transition at $T_2 = 176 \\pm 3$K into an isotropic fluid.\nWe characterize the different phases by calculating various order parameters,\ncoordinate distributions, energetics, spreading pressure and correlation\nfunctions, most of which are in reasonable agreement with available\nexperimental evidence. In addition, we perform simulations where the\nLennard-Jones interaction strength, corrugation potential strength and dihedral\nrigidity are varied in order to better characterize the nature of the two\ntransitions through. We find that both phase transitions are facilitated by a\n``footprint reduction'' of the molecules via tilting, and to a lesser degree\nvia creation of gauche defects in the molecules.",
        "positive": "Nonaffine deformation under compression and decompression of a\n  flow-stabilized solid: Understanding the particle-scale transition from elastic deformation to\nplastic flow is central to making predictions about the bulk material\nproperties and response of disordered materials. To address this issue, we\nperform experiments on flow-stabilized solids composed of micron-scale spheres\nwithin a microfluidic channel, in a regime where particle inertia is\nnegligible. Each solid heap exists within a stress gradient imposed by the\nflow, and we track the positions of particles in response to single impulses of\nfluid-driven compression or decompression. We find that the resulting\ndeformation field is well-decomposed into an affine field, with a constant\nstrain profile throughout the solid, and a non-affine field. The magnitude of\nthis non-affine response decays with the distance from the free surface in the\nlong-time limit, suggesting that the distance from jamming plays a significant\nrole in controlling the length scale of plastic flow. Finally, we observe that\ncompressive pulses create more rearrangements than decompressive pulses, an\neffect that we quantify using the $D^2_\\mathrm{min}$ statistic for non-affine\nmotion. Unexpectedly, the time scale for the compression response is shorter\nthan for decompression at the same strain (but unequal pressure), providing\ninsight into the coupling between deformation and cage-breaking."
    },
    {
        "anchor": "Statistical mechanics of thermal fluctuations of nearly spherical\n  membranes: the influence of bending and stretching elasticities: Theoretical studies of nearly spherical vesicles and microemulsion droplets,\nthat present typical examples for thermally-excited systems that are subject to\nconstraints, are reviewed. We consider the shape fluctuations of such systems\nconstrained by fixed area $A$ and fixed volume $V$, whose geometry is presented\nin terms of scalar spherical harmonics. These constraints can be incorporated\nin the theory in different ways. After an introductory review of the two\napproaches: with an exactly fixed by delta-function membrane area $A$ [Seifert,\nZ. Phys. B, 97, 299, (1995)] or approximatively by means of a Lagrange\nmultiplier $\\sigma$ conjugated to $A$ [Milner and Safran, Phys. Rev. A, 36,\n4371 (1987)], we discuss the determined role of the stretching effects, that\nhas been announced in the framework of a model containing stretching energy\nterm, expressed via the membrane vesicle tension [Bivas and Tonchev,\nPhys.Rev.E, 100, 022416 (2019)]. Since the fluctuation spectrum for the used\nHamiltonian is not exactly solvable an approximating method based on the\nBogoliubov inequalities for the free energy has been developed. The area\nconstraint in the last approach appears as a self-consistent equation for the\nmembrane tension. In the general case this equation is intractable\nanalytically. However, much insight into the physics behind can be obtained\neither imposing some restrictions on the values of the model parameters, or\nstudying limiting cases, in which the self-consistent equation is solved.\nImplications for the equivalence of ensembles have been discussed as well.",
        "positive": "A topologically stabilized metastable fluid in a system of cylindrically\n  confined hard spheres: Metastability in soft condensed matter systems usually results from the\npresence of a nucleation free energy barrier and/or slow dynamics caused by\nhigh density jamming phenomena. Here, we use molecular dynamics and Monte Carlo\nsimulation to show that the interactions between topological defects stabilizes\na chiral helical fluid in a confined quasi-one-dimensional hard sphere fluid\ndramatically slowing its decay toward the equilibrium achiral fluid state.\nAnalysis of thermodynamic, structural and dynamic properties of the system show\nthe equation of state bifurcates continuously at intermediate pressures into\ntwo distinct branches that are accessed from different initial conditions, but\nterminate at the same close packed single helix in the high pressure limit. The\nequilibrium fluid, which forms the high pressure branch as the system is\ncompressed from low density, is characterized by helical sections separated by\nrandomly distributed topological defects that change the helical twist\ndirection giving rise to an achiral fluid. The low pressure metastable branch,\nformed by decompressing the system from the perfect helix, is characterized by\nthe appearance of loosely paired defects that help retain the chiral excess of\nthe original state and stabliize the fluids until it merges continuously with\nthe equilibrium branch at intermediate pressures."
    },
    {
        "anchor": "Nanoscale fluid flows in the vicinity of patterned surfaces: Molecular dynamics simulations of dense and rarefied fluids comprising small\nchain molecules in chemically patterned nano-channels predict a novel switching\nfrom Poiseuille to plug flow along the channel. We also demonstrate behavior\nakin to the lotus effect for a nanodrop on a chemically patterned substrate.\nOur results show that one can control and exploit the behavior of fluids at the\nnanoscale using chemical patterning.",
        "positive": "Planar photonic crystals for express analysis of liquids: The metamaterial based on two planar photonic crystals was used on\nexperimental express analysis of liquids. The metamaterial operates at a\nfrequency of about 9.5 GHz, and has a small size. It was shown experimentally\nthat when the liquid in container was placed in the resonance region at the\ninterface of the two photonic crystals the parameters of resonance peak of\ntransmission coefficient were changed. It was shown experimentally that\ndifferent liquids have a different character of depending of the inverse\nQ-factor and the resonance frequency of the resonance peak on the distance from\nthe interface of the photonic crystals to the container with liquid, and this\ndependence leads to one-to-one identification of such liquid. Thus, the ability\nof express analysis of liquids in a container by using a metamaterial based on\ntwo planar photonic crystals is demonstrated experimentally."
    },
    {
        "anchor": "Surface Instabilities and Magnetic Soft Matter: We report on the formation of surface instabilities in a layer of\nthermoreversible ferrogel when exposed to a vertical magnetic field. Both\nstatic and time dependent magnetic fields are employed. Under variations of\ntemperature, the viscoelastic properties of our soft magnetic matter can be\ntuned. Stress relaxation experiments unveil a stretched exponential scaling of\nthe shear modulus, with an exponent of beta=1/3. The resulting magnetic\nthreshold for the formation of Rosensweig-cusps is measured for different\ntemperatures, and compared with theoretical predictions by Bohlius et. al. in\nJ. Phys.: Condens. Matter., 2006, 18, 2671-2684.",
        "positive": "Ions at hydrophobic interfaces: We argue that the kosmotropes remain strongly hydrated in the vicinity of a\nhydrophobic surface, while the chaotropes lose their hydration shell and can\nbecome adsorbed to the interface. The mechanism of adsorption is still a\nsubject of debate. We argue that there are two driving forces for anionic\nadsorption: the hydrophobic cavitational energy and the interfacial\nelectrostatic surface potential of water. While the cavitational contribution\nto ionic adsorption is now well accepted, the role of the electrostatic surface\npotential is much less clear. The difficulty is that even the sign of this\npotential is a subject of debate, with the ab initio and the classical force\nfield simulations predicting electrostatic surface potentials of opposite sign.\nIn this paper, we will argue that the strong anionic adsorption found in the\npolarizable force field simulations is the result of the artificial\nelectrostatic surface potential present in the classical water models. We will\nshow that if the adsorption of anions were as large as predicted by the\npolarizable force field simulations, the excess surface tension of the NaI\nsolution would be strongly negative, contrary to the experimental measurements.\nWhile the large polarizability of heavy halides is a fundamental property and\nmust be included in realistic modeling of the electrolyte solutions, we argue\nthat the point charge water models, studied so far, are incompatible with the\npolarizable ionic force fields when the translational symmetry is broken. The\ngoal for the future should be the development of water models with very low\nelectrostatic surface potential. We believe that such water models will be\ncompatible with the polarizable force fields, which can then be used to study\nthe interaction of ions with hydrophobic surfaces and proteins."
    },
    {
        "anchor": "Large-scale frictionless jamming with power-law particle size\n  distributions: Due to significant computational expense, discrete element method simulations\nof jammed packings of size-dispersed spheres with size ratios greater than 1:10\nhave remained elusive, limiting the correspondence between simulations and\nreal-world granular materials with large size dispersity. Invoking a recently\ndeveloped neighbor binning algorithm, we generate mechanically-stable jammed\npackings of frictionless spheres with power-law size distributions containing\nup to nearly four million particles with size ratios up to 1:100. By\nsystematically varying the width and exponent of the underlying power laws, we\nanalyze the role of particle size distributions on the structure of jammed\npackings. The densest packings are obtained for size distributions that balance\nthe relative abundance of large-large/intermediate and small-small particle\ncontacts. Although the proportion of rattler particles and mean coordination\nnumber strongly depend on the size distribution, the mean coordination of\nnon-rattler particles attains the frictionless isostatic value of six in all\ncases. The size distribution of non-rattler particles that participate in the\nload-bearing network exhibits no dependence on the width of the total particle\nsize distribution beyond a critical particle size for low-magnitude exponent\npower laws. This signifies that only particles with sizes greater than the\ncritical particle size contribute to the mechanical stability. However, for\nhigh-magnitude exponent power laws, all particle sizes participate in the\nmechanical stability of the packing.",
        "positive": "Spicules and the effect of rigid rods on enclosing membrane tubes: Membrane tubes (spicules) arise in cells, or artificial membranes, in the\nnonlinear deformation regime due to, e.g. the growth of microtubules, actin\nfilaments or sickle hemoglobin fibers towards a membrane. We calculate the\naxial force exerted by the cylindrical membrane tube, and its average radius,\nby taking into account steric interactions between the fluctuating membrane and\nthe enclosed rod. The force required to confine a fluctuating membrane near the\nsurface of the enclosed rod diverges as the separation approaches zero. This\nresults in a smooth crossover of the axial force between a square root and a\nlinear dependence on the membrane tension as the tension increases and the tube\nradius shrinks. This crossover can occur at the most physiologically relevant\nmembrane tensions. Our work may be important in (i) interpreting experiments in\nwhich axial force is related to the tube radius or membrane tension (ii)\ndynamical theories for biopolymer growth in narrow tubes where these\nfluctuation effects control the tube radius."
    },
    {
        "anchor": "Contrasting the dynamics of elastic and non-elastic deformations across\n  an experimental colloidal Martensitic transition: We present a framework to segregate the roles of elastic and non-elastic\ndeformations in the examination of real-space experiments of solid-solid\nMartensitic transitions. The Martensitic transformation of a\nbody-centred-tetragonal(BCT) to a body-centred-orthorhombic(BCO) crystal\nstructure has been studied in a model system of micron-scale ionic microgel\ncolloids. Non-affine fluctuations, i.e., displacement fluctuations that do not\narise from purely elastic(affine) deformations, are detected in particle\nconfigurations acquired from the experiment. Tracking these fluctuations serves\nas a highly sensitive tool in signaling the onset of the Martensitic transition\nand precisely locating particle rearrangements occurring at length scales of a\nfew particle diameters. Particle rearrangements associated with non-affine\ndisplacement modes become increasingly favorable during the transformation\nprocess. The nature of the displacement fluctuation modes that govern the\ntransformation are shown to be different from those predominant in an\nequilibrium crystal. We show that BCO crystallites formed through shear may,\nremarkably, co-exist with those resulting from local rearrangements within the\nsame sample.",
        "positive": "Effective toughness of heterogeneous materials with rate-dependent\n  fracture energy: We investigate dynamic fracture of heterogeneous materials experimentally by\nmeasuring displacement fields as a rupture propagates through a periodic array\nof obstacles of controlled fracture energy. Our measurements demonstrate the\napplicability of the classical equation of motion of cracks at a discontinuity\nof fracture energy: the crack speed jumps at the entrance and exit of an\nobstacle, as predicted by the crack-tip energy balance within the brittle\nfracture framework. The speed jump amplitude is governed by the fracture energy\ncontrast and by the combination of rate-dependency of fracture energy and\ninertia of the medium, which allows the crack to cross a fracture energy\ndiscontinuity at constant energy release rate. This discontinuous dynamics and\nthe rate-dependence cause higher effective toughness, which governs the\ncoarse-grained behavior of these cracks."
    },
    {
        "anchor": "Metallization of colloidal crystals: Colloidal crystals formed by size-asymmetric binary particles co-assemble\ninto a wide variety of colloidal compounds with lattices akin to ionic\ncrystals. Recently, a transition from a compound phase with a sublattice of\nsmall particles to a metal-like phase in which the small particles are\ndelocalized has been predicted computationally and observed experimentally. In\nthis colloidal metallic phase, the small particles roam the crystal maintaining\nthe integrity of the lattice of large particles, as electrons do in metals. A\nsimilar transition also occurs in superionic crystals, termed sublattice\nmelting. Here, we use energetic principles and a generalized molecular dynamics\nmodel of a binary system of functionalized nanoparticles to analyze the\ntransition to sublattice delocalization in different co-assembled crystal\nphases as a function of T, number of grafted chains on the small particles, and\nnumber ratio between the small and large particles $n_s$:$n_l$. We find that\n$n_s$:$n_l$ is the primary determinant of crystal type due to energetic\ninteractions and interstitial site filling, while the number of grafted chains\nper small particle determines the stability of these crystals. We observe\nfirst-order sublattice delocalization transitions as T increases, in which the\nhost lattice transforms from low- to high-symmetry crystal structures,\nincluding A20 to BCT to BCC, Ad to BCT to BCC, and BCC to BCC/FCC to FCC\ntransitions and lattices. Analogous sublattice transitions driven primarily by\nlattice vibrations have been seen in some atomic materials exhibiting an\ninsulator-metal transition also referred to as metallization. We also find\nminima in the lattice vibrations and diffusion coefficient of small particles\nas a function of $n_s$:$n_l$, indicating enhanced stability of certain crystal\nstructures for $n_s$:$n_l$ values that form compounds.",
        "positive": "Detecting Breather Excitations with Inelastic Tunneling Spectroscopy: We propose inelastic electron tunneling spectroscopy scanning tunneling\nmicroscopy (IETS-STM) as a means of exciting and observing intrinsic localized\nmodes (breathers) in a macromolecule. As a demonstration, inelastic tunneling\nfeatures of the density of states are calculated for a simple nonlinear elastic\nMorse chain. The general formalism we have developed for the IETS is applicable\nto other nonlinear extended objects, such as DNA on a substrate."
    },
    {
        "anchor": "Poisson-Fermi Modeling of Ion Activities in Aqueous Single and Mixed\n  Electrolyte Solutions at Variable Temperature: The combinatorial explosion of empirical parameters in tens of thousands\npresents a tremendous challenge for extended Debye-H\\\"uckel models to calculate\nactivity coefficients of aqueous mixtures of most important salts in chemistry.\nThe explosion of parameters originates from the phenomenological extension of\nthe Debye-H\\\"uckel theory that does not take steric and correlation effects of\nions and water into account. In contrast, the Poisson-Fermi theory developed in\nrecent years treats ions and water molecules as nonuniform hard spheres of any\nsize with interstitial voids and includes ion-water and ion-ion correlations.\nWe present a Poisson-Fermi model and numerical methods for calculating the\nindividual or mean activity coefficient of electrolyte solutions with any\narbitrary number of ionic species in a large range of salt concentrations and\ntemperatures. For each activity-concentration curve, we show that the\nPoisson-Fermi model requires only three unchanging parameters at most to well\nfit the corresponding experimental data. The three parameters are associated\nwith the Born radius of the solvation energy of an ion in electrolyte solution\nthat changes with salt concentrations in a highly nonlinear manner.",
        "positive": "A new finite element paradigm to solve contact problems with roughness: This article's main scope is the presentation of a computational method for\nthe simulation of contact problems within the finite element method involving\ncomplex and rough surfaces. The approach relies on the MPJR (eMbedded Profile\nfor Joint Roughness) interface finite element proposed in [arXiv:1805.07207],\nwhich is nominally flat but can embed at the nodal level any arbitrary height\nto reconstruct the displacement field due to contact in the presence of\nroughness. Here, the formulation is generalized to handle 3D surface height\nfields and any arbitrary nonlinear interface constitutive relation, including\nfriction and adhesion. The methodology is herein validated with BEM solutions\nfor linear elastic contact problems. Then, a selection of nonlinear contact\nproblems prohibitive to be simulated by BEM and by standard contact algorithms\nin FEM are detailed, to highlight the promising aspects of the proposed method\nfor tribology."
    },
    {
        "anchor": "Traveling Granular Segregation Patterns in a Long Drum Mixer: Mixtures of granular media often exhibit size segregation along the axis of a\npartially-filled, horizontal, rotating cylinder. Previous experiments have\nobserved axial bands of segregation that grow from concentration fluctuations\nand merge in a manner analogous to spinodal decomposition. We have observed\nthat a new dynamical state precedes this effect in certain mixtures:\nbi-directional traveling waves. By preparing initial conditions, we found that\nthe wave speed decreased with wavelength. Such waves appear to be inconsistent\nwith simple PDE models which are first order in time.",
        "positive": "Flowering of Developable 2D Crystal Shapes in Closed, Fluid Membranes: The morphologies of two-dimensional (2D) crystals, nucleated, grown, and\nintegrated within 2D elastic fluids, for instance in giant vesicle membranes,\nare dictated by an interplay of mechanics, permeability, and thermal\ncontraction. Mitigation of solid strain drives formation of crystals with\ndevelopable shapes (e.g. planar or cylindrical) that expel Gaussian curvature\ninto the 2D fluid. However, upon cooling to grow the crystals, large vesicles\nsustain greater inflation and tension because their small area to volume ratio\nslows water permeation. As a result, more elaborate shapes, for instance\nflowers with bendable but inextensible petals form on large vesicles despite\ntheir more gradual curvature, while small vesicles harbor compact planar\ncrystals. This size dependence runs counter to the known cumulative growth of\nstrain energy of 2D colloidal crystals on rigid spherical templates. This\ninterplay of intra-membrane mechanics and processing points to the scalable\nproduction of flexible molecular crystals of controllable complex shape."
    },
    {
        "anchor": "Hydrodynamic interaction in confined geometries: This article gives an overview of recent theoretical and experimental\nfindings concerning the hydrodynamic interaction between liquid-embedded\nparticles in various confined geometries. A simple unifying description\nemerges, which accounts for the various findings based on the effect of\nconfinement on conserved fields of the embedding liquid. It shows, in\nparticular, that the hydrodynamic interaction under confinement remains\nlong-ranged, decaying algebraically with inter-particle distance, except for\nthe case of confinement in a rigid linear channel.",
        "positive": "Molecular insights on Poly(N-isoproylacrylamide) coil-to-globule\n  transition induced by pressure: Poly-N-isopropylacrylamide (PNIPAM) phase diagram is explored in a wide range\nof temperature and pressure using extensive all-atom molecular dynamics\nsimulations. By exploiting a simple model of an atactic linear polymer chain,\nwe provide novel insights into PNIPAM coil-to-globule transition addressing the\nroles played by both temperature and pressure. We find that a coil-to-globule\ntransition exists up to large pressures, undergoing an intriguing reentrant\nbehavior of the lower critical solution temperature with increasing pressure in\nagreement with experimental observations. Furthermore, we report the existence\nof a new kind of globular state at high pressures, again confirming\nexperimental results: this is characterized by a more structured hydration\nshell, that is closer to PNIPAM hydrophobic domains, with respect to the\natmospheric pressure counterpart. Our results clearly show that temperature and\npressure induce PNIPAM coil-to-globule transition through different molecular\nmechanisms, opening the way for a systematic use of both thermodynamic\nparameters to tune the location of the transition and the properties of the\nassociated swollen/collapsed states."
    },
    {
        "anchor": "Variational theory for site resolved protein folding free energy\n  surfaces: We present a microscopic variational theory for the free energy surface of a\nfast folding protein that allows folding kinetics to be resolved to the residue\nlevel using Debye-Waller factors as local order parameters. We apply the method\nto lambda-repressor and compare with site directed mutagenesis experiments. The\nformation of native structure and the free energy profile along the folding\nroute are shown to be well described by the capillarity approximation but with\nsome fine structure due to local folding topology.",
        "positive": "Model for the free-volume distributions of equilibrium fluids: We introduce and test via molecular simulation a simple model for predicting\nthe manner in which interparticle interactions and thermodynamic conditions\nimpact the single-particle free-volume distributions of equilibrium fluids. The\nmodel suggests a scaling relationship for the density-dependent behavior of the\nhard-sphere system. It also predicts how the second virial coefficients of\nfluids with short-range attractions affect their free-volume distributions."
    },
    {
        "anchor": "Self-consistent generalized Langevin equation theory of the dynamics of\n  multicomponent atomic liquids: A fundamental challenge of the theory of liquids is to understand the\nsimilarities and differences in the macroscopic dynamics of both colloidal and\natomic liquids, which originate in the (Newtonian or Brownian) nature of the\nmicroscopic motion of their constituents. Starting from the recently-discovered\nlong-time dynamic equivalence between a colloidal and an atomic liquid that\nshare the same interparticle pair potential, in this work we develop a\nself-consistent generalized Langevin equation (SCGLE) theory for the dynamics\nof equilibrium multicomponent atomic liquids, applicable as an approximate but\nquantitative theory describing the long-time diffusive dynamical properties of\nsimple equilibrium atomic liquids. When complemented with a Gaussian-like\napproximation, this theory is also able to provide a reasonable representation\nof the passage from ballistic to diffusive behavior. We illustrate the\napplicability of the resulting theory with three particular examples, namely, a\nmonodisperse and a polydisperse monocomponent hard-sphere liquid, and a highly\nsize-asymmetric binary hard-sphere mixture. To assess the quantitative accuracy\nof our results, we perform event-driven molecular dynamics simulations, which\ncorroborate the general features of the theoretical predictions.",
        "positive": "Shear Banding of Complex Fluids: Even in simple geometries many complex fluids display non-trivial flow\nfields, with regions where shear is concentrated. The possibility for such\nshear banding has been known since several decades, but the recent years have\nseen an upsurge of studies offering an ever more precise understanding of the\nphenomenon. The development of new techniques to probe the flow on multiple\nscales and with increasing spatial and temporal resolution has opened the\npossibility for a synthesis of the many phenomena that could only have been\nthought of separately before. In this review, we bring together recent research\non shear banding in polymeric and on soft glassy materials, and highlight their\nsimilarities and disparities."
    },
    {
        "anchor": "Liquid marbles as thermally robust droplets: coating-assisted\n  Leidenfrost-like effect: The Leidenfrost effect-prolonged evaporation of droplets on a superheated\nsurface-happens only when the surface temperature is above a certain\ntransitional value. Here, we show that specially engineered droplets - liquid\nmarbles - can exhibit similar effect at any superheated temperatures (up to 465\noC tested in our experiment) without a transition. Very possibly, this\nphenomenon is due to the fact that liquid marbles are droplets coated with\nmicroparticles and these microparticles help levitate the liquid core and\nmaintain an insulation layer between the liquid and the superheated surface.",
        "positive": "Random Packings of Frictionless Particles: We study random packings of frictionless particles at T=0.\n  The packing fraction where the pressure becomes nonzero is the same as the\njamming threshold, where the static shear modulus becomes nonzero. The\ndistribution of threshold packing fractions narrows and its peak approaches\nrandom close-packing as the system size increases. For packing fractions within\nthe peak, there is no self-averaging, leading to exponential decay of the\ninterparticle force distribution."
    },
    {
        "anchor": "Two- and three-phase equilibria in polydisperse Yukawa hard-sphere\n  mixture. High temperature and mean spherical approximations: Phase behavior of the Yukawa hard-sphere polydisperse mixture with high\ndegree of polydispersity is studied using high temperature approximation (HTA)\nand mean spherical approximation (MSA). We have extended and applied the scheme\ndeveloped to calculate the phase diagrams of polydisperse mixtures described by\nthe truncatable free energy models, i.e., the models with Helmholtz free energy\ndefined by the finite number of the moments of the species distribution\nfunction. At high degree of polydispersity, several new features in the\ntopology of the two-phase diagram have been observed: the cloud and shadow\ncurves intersect twice and each of them forms a closed loop of the\nellipsoidal-like shape with the liquid and gas branches of the cloud curve\nalmost coinciding. Approaching a certain limiting value of the polydispersity\nindex, the cloud and shadow curves shrink and disappear. Beyond this limiting\nvalue, polydispersity induces the appearance of the three-phase equilibrium at\nlower temperatures. We present and analyze corresponding phase diagrams\ntogether with distribution functions of three coexisting phases. In general,\ngood agreement was observed between predictions of the two different\ntheoretical methods, i.e., HTA and MSA. Our results confirm qualitative\npredictions for the three-phase coexistence obtained earlier within the\nframework of the van der Waals approach.",
        "positive": "Hydrodynamic synchronisation of non-linear oscillators at low Reynolds\n  number: We introduce a generic model of weakly non-linear self-sustained oscillator\nas a simplified tool to study synchronisation in a fluid at low Reynolds\nnumber. By averaging over the fast degrees of freedom, we examine the effect of\nhydrodynamic interactions on the slow dynamics of two oscillators and show that\nthey can lead to synchronisation. Furthermore, we find that synchronisation is\nstrongly enhanced when the oscillators are non-isochronous, which on the limit\ncycle means the oscillations have an amplitude-dependent frequency.\nNon-isochronity is determined by a nonlinear coupling $\\alpha$ being non-zero.\nWe find that its ($\\alpha$) sign determines if they synchronise in- or\nanti-phase. We then study an infinite array of oscillators in the long\nwavelength limit, in presence of noise. For $\\alpha > 0$, hydrodynamic\ninteractions can lead to a homogeneous synchronised state. Numerical\nsimulations for a finite number of oscillators confirm this and, when $\\alpha\n<0$, show the propagation of waves, reminiscent of metachronal coordination."
    },
    {
        "anchor": "Theory of domain patterns in systems with long-range interactions of\n  Coulomb type: We develop a theory of the domain patterns in systems with competing\nshort-range attractive interactions and long range repulsive Coulomb\ninteractions. We take an energetic approach, in which patterns are considered\nas critical points of a mean-field free energy functional. Close to the\nmicrophase separation transition, this functional takes on a universal form,\nallowing to treat a number of diverse physical situations within a unified\nframework. We use asymptotic analysis to study domain patterns with sharp\ninterfaces. We derived an interfacial representation of the pattern's free\nenergy which remains valid in the fluctuating system, with a suitable\nrenormalization of the Coulomb interaction's coupling constant. We also derived\nintegrodifferential equations describing the stationary domain patterns of\narbitrary shapes and their thermodynamic stability, coming from the first and\nsecond variation of the interfacial free energy. We showed that the length\nscale of a stable domain pattern must obey a certain scaling law with the\nstrength of the Coulomb interaction. We analyzed existence and stability of\nlocalized (spots, stripes, annuli) and periodic (lamellar, hexagonal) patterns\nin two dimensions. We showed that these patterns are metastable in certain\nranges of the parameters and that they can undergo morphological instabilities\nleading to the formation of more complex patterns. We discuss nucleation of the\ndomain patterns by thermal fluctuations and pattern formation scenarios for\nvarious thermal quenches. We argue that self-induced disorder is an intrinsic\nproperty of the domain patterns in the systems under consideration.",
        "positive": "Swimming of microorganisms in quasi-2D membranes: Biological swimmers frequently navigate in geometrically restricted media. We\nstudy the prescribed-stroke problem of swimmers confined to a planar viscous\nmembrane embedded in a bulk fluid of different viscosity. In their motion,\nmicroscopic swimmers disturb the fluid in both the membrane and the bulk. The\nflows that emerge have a combination of two-dimensional (2D) and\nthree-dimensional (3D) hydrodynamic features, and such flows are referred to as\nquasi-2D. The cross-over from 2D to 3D hydrodynamics in a quasi-2D fluid is\ncontrolled by the Saffman length, a length scale given by the ratio of the 2D\nmembrane viscosity to the 3D viscosity of the embedding bulk fluid. We have\ndeveloped a computational and theoretical approach based on the boundary\nelement method and the Lorentz reciprocal theorem to study the swimming of\nmicroorganisms for a range of values of the Saffman length. We found that a\nflagellum propagating transverse sinusoidal waves in a quasi-2D membrane can\ndevelop a swimming speed exceeding that in pure 2D or 3D fluids, while the\npropulsion of a two-dimensional squirmer is slowed down by the presence of the\nbulk fluid."
    },
    {
        "anchor": "Curvature dynamics and long-range effects on fluid-fluid interfaces with\n  colloids: We investigate the dynamics of a phase-separating binary fluid, containing\ncolloidal dumbbells anchored to the fluid-fluid interface. Extensive Lattice\nBoltzmann-Immersed Boundary method simulations reveal that the presence of soft\ndumbbells can significantly affect the curvature dynamics of the interface\nbetween phase-separating fluids, even though the coarsening dynamics is left\nnearly unchanged. In addition, our results show that the curvature dynamics\nexhibits distinct non-local effects, which might be exploited for the design of\nnew soft mesoscale materials. We point out that the inspection of the\nstatistical dynamics of the curvature can disclose new insights into local\ninhomogeneities of the binary fluid configuration, as a function of the volume\nfraction and aspect ratio of the dumbbells.",
        "positive": "Oscillations of Spherical and Cylindrical Shells: We have found the complete spectrum and eigenstates for harmonic oscillations\nof ideal spherical and cylindrical shells, both being infinitely thin. The\nspectrum of the cylindrical shell has an infinite number of Goldstone modes\ncorresponding to folding deformations. This infrared catostrophe is overcome by\naccounting for curvature-part of energy."
    },
    {
        "anchor": "Evidence for the weak steric hindrance scenario in the supercooled-state\n  reorientational dynamics: We use molecular-dynamics computer simulations to study the translational and\nreorientational dynamics of a glass-forming liquid of dumbbells. For\nsufficiently elongated molecules the standard strong steric hindrance scenario\nfor the rotational dynamics is found. However, for small elongations we find a\ndifferent scenario -- the weak steric hindrance scenario -- caused by a new\ntype of glass transition in which the orientational dynamics of the molecule's\naxis undergoes a dynamical transition with a continuous increase of the\nnon-ergodicity parameter. These results are in agreement with the theoretical\npredictions by the mode-coupling theory for the glass transition.",
        "positive": "Wall curvature driven dynamics of a microswimmer: Microorganisms navigate through fluid, often confined by complex\nenvironments, to survive and sustain life. Inspired by this fact, we consider a\nmodel system and seek to understand the wall curvature driven dynamics of a\nsquirmer, a mathematical model for a microswimmer, using (i) lattice Boltzmann\nsimulations and (ii) analytical theory by \\citet{dario_gareth}. The\ninstantaneous dynamics of the system is presented in terms of fluid velocity\nfields, and the translational and angular velocities of the microswimmer,\nwhereas the long time dynamics is presented by plotting the squirmer\ntrajectories near curved boundaries in physical and dynamical space, as well as\ncharacterising them in terms of (i) proximity parameter, (ii) retention time,\n(iii) swimmer orientation and (iv) tangential velocity near the boundary, and\n(v) scattering angle during the collision. Our detailed analysis shows that\nirrespective of the type and strength, microswimmers exhibit a greater affinity\ntowards a concave boundary due to hydrodynamic interactions compared to a\nconvex boundary. In the presence of additional repulsive interactions with the\nboundary, we find that pullers (propel by forward thrust) have a slightly\ngreater affinity towards the convex--curved walls compared to pushers (propel\nby backward thrust). Our study provides a comprehensive understanding of the\nconsequence of hydrodynamic interactions in a unified framework that\nencompasses the dynamics of pullers, pushers, and neutral swimmers in the\nneighbourhood of flat, concave, and convex walls. In addition, the combined\neffect of oppositely curved surfaces is studied by confining the squirmer in an\nannulus. The results presented in a unified framework and insights obtained are\nexpected to be useful to design geometrical confinements to control and guide\nthe motion of microswimmers in microfluidic applications."
    },
    {
        "anchor": "Colloidal glass transition observed in confinement: We study a colloidal suspension confined between two quasi-parallel walls as\na model system for glass transitions in confined geometries. The suspension is\na mixture of two particle sizes to prevent wall-induced crystallization. We use\nconfocal microscopy to directly observe the motion of colloidal particles. This\nmotion is slower in confinement, thus producing glassy behavior in a sample\nwhich is a liquid in an unconfined geometry. For higher volume fraction samples\n(closer to the glass transition), the onset of confinement effects occurs at\nlarger length scales.",
        "positive": "Heterogeneity promotes first to second order phase transition on\n  flocking systems: We have considered a variation of the Vicsek model with vectorial noise where\neach one of the agents have their own noise amplitude normally distributed\naround a mean value, $\\mu$, with standard deviation $\\sigma$. First-order phase\ntransition are observed for standard deviation\n$0\\leq\\sigma<\\sigma_{tri}\\approx0.11$, whereas for larger values, up to\n$\\sigma=0.3$, a continuous phase transition occurs. For values of $\\sigma$ in\nthe interval $0.15\\leq\\sigma\\leq0.30$ the continuous nature of the observed\ntransition is characterized by means of finite-size scaling techniques, that\nalso allow us to estimate the exponents driving the transition. A study of\nbands stability suggests that no band can form in this regime. Inspired by\nbiological facts, the perception heterogeneity introduced in the model trough\n$\\sigma$, allow us to tune the collective behaviour of the system."
    },
    {
        "anchor": "Holes and cracks in rigid foam films: The classical problem of foam film rupture dynamics has been investigated\nwhen surfaces exhibit very high rigidity due to the presence of specific\nsurfactants. Two new features are reported. First a strong deviation to the\nwell-known Taylor-Culick law is observed. Then, crack-like patterns can be\nvisualized in the film; these patterns are shown to appear at a well defined\ndeformation. The key role of surface active material on these features is\nquantitatively investigated, pointing the importance of surface elasticity to\ndescribe these fast dynamical processes, and thus providing an alternative tool\nto characterize surface elasticity in conditions extremely far from\nequilibrium. The origin of the cracks and their consequences on film rupturing\ndynamics are also discussed.",
        "positive": "Selectively embedding multiple spatially steered fibers in polymer\n  composite parts made using vat photopolymerization: Fiber-Reinforced Polymer Composite (FRPC) parts are mostly made as laminates,\nshells, or surfaces wound with 2D fiber patterns even after the emergence of\nadditive manufacturing. Making FRPC parts with embedded continuous fibers in 3D\nis not reported previously even though topology optimization shows that such\ndesigns are optimal. Earlier attempts in 3D fiber reinforcement have\ndemonstrated additively manufactured parts with channels into which fibers are\ninserted. In this paper, we present 3D printing techniques along with a printer\ndeveloped for printing parts with continuous fibers that are spatially embedded\ninside the matrix using a variant of vat photopolymerization. Multiple\ncontinuous fibers are gradually steered as the part is built layer upon layer\ninstead of placing them inside channels made in the part. We show examples of\nspatial fiber patterns and geometries built using the 3D printing techniques\ndeveloped in this work. We also test the parts for strength and illustrate the\nimportance of spatially embedding fibers in specific patterns."
    },
    {
        "anchor": "Catapulting of topological defects through elasticity bands in active\n  nematics: Active materials are those in which individual, uncoordinated local stresses\ndrive the material out of equilibrium on a global scale. Examples of such\nassemblies can be seen across scales from schools of fish to the cellular\ncytoskeleton and underpin many important biological processes. Synthetic\nexperiments that recapitulate the essential features of such active systems\nhave been the object of study for decades as their simple rules allow us to\nelucidate the physical underpinnings of collective motion. One system of\nparticular interest has been active nematic liquid crystals (LCs). Because of\ntheir well understood passive physics, LCs provide a rich platform to\ninterrogate the effects of active stress. The flows and steady state structures\nthat emerge in an active LCs have been understood to result from a competition\nbetween nematic elasticity and the local activity. However most investigations\nof such phenomena consider only the magnitude of the elastic resistance and not\nits peculiarities. Here we investigate a nematic liquid crystal and selectively\nchange the ratio of the material's splay and bend elasticities. We show that\nincreases in the nematic's bend elasticity specifically drives the material\ninto an exotic steady state where elongated regions of acute bend distortion or\n\"elasticity bands\" dominate the structure and dynamics. We show that these\nbands strongly influence defect dynamics, including the rapid motion or\n\"catapulting\" along the disintegration of one of these bands thus converting\nbend distortion into defect transport. Thus, we report a novel dynamical state\nresultant from the competition between nematic elasticity and active stress.",
        "positive": "Electrostatic Interaction of Heterogeneously Charged Surfaces with\n  Semipermeable Membranes: In this paper we study the electrostatic interaction of a heterogeneously\ncharged wall with a neutral semipermeable membrane. The wall consists of\nperiodic stripes, where the charge density varies in one direction. The\nmembrane is in a contact with a bulk reservoir of an electrolyte solution and\nseparated from the wall by a thin film of salt-free liquid. One type of ions\n(small counterions) permeates into the gap and gives rise to a\ndistance-dependent membrane potential, which translates into a repulsive\nelectrostatic disjoining pressure due to an overlap of counterion clouds in the\ngap. To quantify it we use two complementary approaches. First, we propose a\nmean-field theory based on a linearized Poisson-Boltzmann equation and Fourier\nanalysis. These calculations allow us to estimate the effect of a heterogeneous\ncharge pattern at the wall on the induced heterogeneous membrane potential, and\nthe value of the disjoining pressure as a function of the gap. Second, we\nperform Langevin dynamics simulations of the same system with explicit ions.\nThe results of the two approaches are in good agreement with each other at low\nsurface charge and small gap, but differ due to nonlinearity at the higher\ncharge. These results demonstrate that a heterogeneity of the wall charge can\nlead to a huge reduction in the electrostatic repulsion, which could\ndramatically facilitate a self-assembly in complex synthetic and biological\nsystems."
    },
    {
        "anchor": "Inhomogeneous Cooling of the Rough Granular Gas in Two Dimensions: We study the inhomogeneous clustered regime of a freely cooling granular gas\nof rough particles in two dimensions using large-scale event driven simulations\nand scaling arguments. During collisions, rough particles dissipate energy in\nboth the normal and tangential directions of collision. In the inhomogeneous\nregime, translational kinetic energy and the rotational energy decay with time\n$t$ as power-laws $t^{-\\theta_T}$ and $t^{-\\theta_R}$. We numerically determine\n$\\theta_T \\approx 1$ and $\\theta_R \\approx 1.6$, independent of the\ncoefficients of restitution. The inhomogeneous regime of the granular gas has\nbeen argued to be describable by the ballistic aggregation problem, where\nparticles coalesce on contact. Using scaling arguments, we predict $\\theta_T=1$\nand $\\theta_R=1$ for ballistic aggregation, $\\theta_R$ being different from\nthat obtained for the rough granular gas. Simulations of ballistic aggregation\nwith rotational degrees of freedom are consistent with these exponents.",
        "positive": "The statistical physics of active matter: from self-catalytic colloids\n  to living cells: These lecture notes are designed to provide a brief introduction into the\nphenomenology of active matter and to present some of the analytical tools used\nto rationalize the emergent behavior of active systems. Such systems are made\nof interacting agents able to extract energy stored in the environment to\nproduce sustained directed motion. The local conversion of energy into\nmechanical work drives the system far from equilibrium, yielding new dynamics\nand phases. The emerging phenomena can be classified depending on the symmetry\nof the active particles and on the type of microscopic interactions. We focus\nhere on steric and aligning interactions, as well as interactions driven by\nshape changes. The models that we present are all inspired by experimental\nrealizations of either synthetic, biomimetic or living systems. Based on\nminimal ingredients, they are meant to bring a simple and synthetic\nunderstanding of the complex phenomenology of active matter."
    },
    {
        "anchor": "Granular matter instability: A structural rigidity point of view: Stress paths in granular matter often suffer sudden large-scale\nrearrangements when the system is slightly perturbed, i.e. granular systems are\nunstable. We show in this paper that the observed instability is due to the\nminimally rigid, or isostatic, character of the system's contact network. It is\nfirst demonstrated that the contact network of a granular packing becomes\nisostatic (minimally rigid) in any dimension in the limit of large\nstiffness-to-load ratio. We next show that, in this isostatic limit, the\nload-stress response function becomes power-law distributed and takes\nexponentially large (growing as exp(H) where H is the system's height) positive\nand negative values. Large negative values of the load-stress response function\nimply instability, since only positive (compressive) stresses are allowed in\nnon-cohesive granular packings. Thus there is an isostatic phase transition in\nthe limit of large stiffness (or small load), and the resulting isostatic phase\nhas an anomalously large susceptibility to perturbation.",
        "positive": "Thermodynamic approach to dense granular matter: a numerical realization\n  of a decisive experiment: Years ago Edwards proposed a thermodynamic description of dense granular\nmatter, in which the grains (the `atoms' of the system) interact with inelastic\nforces. The approach is intriguing but is not justified from first principles,\nand hence, in the absence of conclusive tests of its validity, it has not been\nwidely accepted. We perform a numerical experiment with a realistic granular\nmatter model specially conceived to be reproducible in the laboratory. The\nresults strongly support the thermodynamic picture."
    },
    {
        "anchor": "Novel Colloidal Crystalline States on Two Dimensional Periodic\n  Substrates: We show using numerical simulations that a rich variety of novel colloidal\ncrystalline states are realized on square and triangular two dimensional\nperiodic substrates which can be experimentally created using crossed laser\narrays. When there are more colloids than potential substrate minima, multiple\ncolloids are trapped at each substrate minima and act as a single particle with\na rotational degree of freedom, giving rise to a new type of orientational\norder. We call these states colloidal molecular crystals. A two-step melting\ncan also occur in which individual colloidal molecules initially rotate,\ndestroying the overall orientational order, followed by the onset of inter-well\ncolloidal hopping.",
        "positive": "Free Energy of Multiple Overlapping Chains: How accurate is pair additivity in describing interactions between soft\npolymer-based nanoparticles? Using numerical simulations we compute the free\nenergy cost required to overlap multiple chains in the same region of space,\nand provide a quantitative measure of the effectiveness of pair additivity as a\nfunction of chain number and length. Our data suggest that pair additivity can\nindeed become quite inadequate as the chain density in the overlapping region\nincreases. We also show that even a scaling theory based on polymer confinement\ncan only partially account for the complexity of the problem. In fact, we\nunveil and characterize an isotropic to star-polymer cross-over taking place\nfor large number of chains, and propose a revised scaling theory that better\ncaptures the physics of the problem."
    },
    {
        "anchor": "Scaling theory of DNA confined in nanochannels and nanoslits: A scaling analysis is presented of the statistics of long DNA confined in\nnanochannels and nanoslits. It is argued that there are several regimes in\nbetween the de Gennes and Odijk limits introduced long ago. The DNA chain folds\nback on itself giving rise to a global persistence length which may be very\nlarge owing to entropic deflection. Moreover, there is an orientational\nexcluded-volume effect between the DNA segments imposed solely by the\nnanoconfinement. These two effects cause the chain statistics to be intricate\nleading to nontrivial power laws for the chain extension in the intermediate\nregimes. It is stressed that DNA confinement within nanochannels differs from\nthat in nanoslits because the respective orientational excluded-volume effects\nare not the same.",
        "positive": "Limit cycles turn active matter into robots: Active matter composed of energy-generating microscopic constituents is a\npromising platform to create autonomous functional materials. However, the very\npresence of these microscopic energy sources is what makes active matter prone\nto dynamical instabilities and hence hard to control. Here, we show that these\ninstabilities can be coaxed into work-generating limit cycles that turn active\nmatter into robots. We illustrate this general principle in odd active media,\nmodel systems whose interaction forces are as simple as textbook molecular\nbonds yet not constrained to be the gradient of a potential. These emergent\nrobotic functionalities are demonstrated by revisiting what is arguably the\noldest of inventions: the wheel. Unlike common wheels that are driven by\nexternal torques, an odd wheel undergoes work-generating limit cycles that\nallow it to roll autonomously uphill by virtue of its own deformation, as\ndemonstrated by our prototypes. Similarly, familiar scattering phenomena, like\na ball bouncing off a wall, turn into basic robotic manipulations when either\nthe ball or the wall is odd. Using continuum mechanics, we reveal collective\nrobotic mechanisms that steer the outcome of collisions or influence the\nabsorption of impacts in experiments. Beyond robotics, work-generating limit\ncycles can also control the non-linear dynamics of active soft materials,\nbiological systems and driven nanomechanical devices."
    },
    {
        "anchor": "Crystallinity and Crystallographic Texture in Isotactic Polypropylene\n  during Deformation and Heating: The development of the crystallinity and of the crystallographic orientation\nof isotactic polypropylene (iPP) during rolling deformation and subsequent heat\ntreatment is studied. The experiments are conducted by using X-ray diffraction\nwith an area detector. The evolution of crystallographic orientation is tracked\nby calculating the pole figures and by applying a quantitative 3D texture\ncomponent fit method. The rolling orientation after a true strain of -1.5\nmainly consists of the (010)[001], (130)[001], and [001]//RD fiber components\n(RD: rolling direction). The results reveal that the crystallinity drastically\ndecreases during rolling. We suggest that decrystallization (disaggregation) is\na deformation mechanism which takes place as a microscopic alternative to\ncrystallographic intralamellar shear depending on the orientation of the\nlamellae relative to the imposed deformation tensor. Heat treatment after\nrolling leads to the recrystallization of amorphous material and to a strong\nenhancement of the fiber orientation component. The recrystallization\norientation is explained in terms of an oriented nucleation mechanism where\namorphous material aligns along existing crystalline lamellae blocks which\nprevailed during the preceding deformation.",
        "positive": "Spontaneous symmetry breaking in active droplets provides a generic\n  route to motility: We explore a generic mechanism whereby a droplet of active matter acquires\nmotility by the spontaneous breakdown of a discrete symmetry. The model we\nstudy offers a simple representation of a \"cell extract\" comprising, e.g., a\ndroplet of actomyosin solution. (Such extracts are used experimentally to model\nthe cytoskeleton.) Actomyosin is an active gel whose polarity describes the\nmean sense of alignment of actin fibres. In the absence of polymerization and\ndepolymerization processes ('treadmilling'), the gel's dynamics arises solely\nfrom the contractile motion of myosin motors; this should be unchanged when\npolarity is inverted. Our results suggest that motility can arise in the\nabsence of treadmilling, by spontaneous symmetry breaking (SSB) of polarity\ninversion symmetry. Adapting our model to wall-bound cells in two dimensions,\nwe find that as wall friction is reduced, treadmilling-induced motility falls\nbut SSB-mediated motility rises. The latter might therefore be crucial in three\ndimensions where frictional forces are likely to be modest. At a supra-cellular\nlevel, the same generic mechanism can impart motility to aggregates of\nnon-motile but active bacteria; we show that SSB in this (extensile) case leads\ngenerically to rotational as well as translational motion."
    },
    {
        "anchor": "Multifunctional Composites for Elastic and Electromagnetic Wave\n  Propagation: Composites are ideally suited to achieve desirable multifunctional effective\nproperties since the best properties of different materials can be judiciously\ncombined with designed microstructures. Here we establish cross-property\nrelations for two-phase composite media that link effective elastic and\nelectromagnetic wave characteristics to one another, including the respective\neffective wave speeds and attenuation coefficients, which facilitate\nmultifunctional material design. This is achieved by deriving accurate formulas\nfor the effective electromagnetic and elastodynamic properties that depend on\nthe wavelengths of the incident waves and the microstructure via the spectral\ndensity. Our formulas enable us to explore the wave characteristics of a broad\nclass of disordered microstructures because they apply, unlike conventional\nformulas, for a wide range of incident wavelengths, i.e., well beyond the\nlong-wavelength regime. This capability enables us to study the dynamic\nproperties of exotic disordered ``hyperuniform'' composites that can have\nadvantages over crystalline ones, such as nearly optimal, direction-independent\nproperties and robustness against defects. We specifically show that disordered\n``stealthy'' hyperuniform microstructures exhibit novel wave characteristics,\ne.g., low-pass filters that transmit waves ``isotropically'' up to a finite\nwavenumber. Our cross-property relations for the effective wave characteristics\ncan be applied to design multifunctional composites via inverse techniques.\nDesign examples include structural components that require high stiffness and\nelectromagnetic absorption, heat-sinks for CPUs, and sound-absorbing housings\nfor motors that have to efficiently emit thermal radiation and suppress\nmechanical vibrations, and nondestructive evaluation of the elastic moduli of\nmaterials from the effective dielectric response.",
        "positive": "Bacteria driving droplets: We confine a dense suspension of motile \\textit{Escherichia coli} inside a\nspherical droplet in a water-in-oil emulsion, creating a \"bacterially\"\npropelled droplet. We show that droplets move in a persistent random walk, with\na persistence time $\\tau\\sim 0.3\\, {\\rm s}$, a long-time diffusion coefficient\n$D\\sim 0.5\\, \\mu {\\rm m}^2/{\\rm s}$, and an average instantaneous speed $V\\sim\n1.5\\, \\mu{\\rm m/s}$ when the bacterial suspension is at the maximum studied\nconcentration. Several droplets are analyzed, varying the drop radius and\nbacterial concentration. We show that the persistence time, diffusion\ncoefficient and average speed increase with the bacterial concentration inside\nthe drop, but are largely independent of the droplet size. By measuring the\nturbulent-like motion of the bacteria inside the drop, we demonstrate that the\nmean velocity of the bacteria near the bottom of the drop, which is separated\nfrom a glass substrate by a thin lubrication oil film, is antiparallel to the\ninstantaneous velocity of the drop. This suggests that the driving mechanism is\na slippery rolling of the drop over the substrate, caused by the collective\nmotion of the bacteria. Our results show that microscopic organisms can\ntransfer useful mechanical energy to their confining environment, opening the\nway to the assembly of mesoscopic motors composed of microswimmers."
    },
    {
        "anchor": "DNA Twist Elasticity: Mechanics and Thermal Fluctuations: The elastic properties of semiflexible polymers are of great importance in\nbiology. There are experiments on biopolymers like double stranded DNA, which\ntwist and stretch single molecules to probe their elastic properties. It is\nknown that thermal fluctuations play an important role in determining molecular\nelastic properties, but a full theoretical treatment of the problem of twist\nelasticity of fluctuating ribbons using the simplest worm like chain model\n(WLC) remains elusive. In this paper, we approach this problem by taking first\na mechanical approach and then incorporating thermal effects in a quadratic\napproximation applying the Gelfand-Yaglom (GY) method for computing fluctuation\ndeterminants. Our study interpolates between mechanics and statistical\nmechanics in a controlled way and shows how profoundly thermal fluctuations\naffect the elasticity of semiflexible polymers. The new results contained here\nare: 1) a detailed study of the minimum energy configurations with explicit\nexpressions for their energy and writhe and plots of the extension versus Link\nfor these configurations. 2) a study of fluctuations around the local minima of\nenergy and approximate analytical formulae for the free energy of stretched\ntwisted polymers derived by the Gelfand Yaglom method. We use insights derived\nfrom our mechanical approach to suggest calculational schemes that lead to an\nimproved treatment of thermal fluctuations. From the derived formulae,\npredictions of the WLC model for molecular elasticity can be worked out for\ncomparison against numerical simulations and experiments.",
        "positive": "Two-step build-up of a thermoreversible polymer network: From early\n  local to late collective dynamics: We probe the mechanisms at work in the build-up of thermoreversible gel\nnetworks, with the help of hybrid gelatin gels containing a controlled density\nof irreversible, covalent crosslinks (CL), which we quench below the physical\ngelation temperature. The detailed analysis of the dependence on covalent\ncrosslink density of both the shear modulus and optical activity evolutions\nwith time after quench enables us to identify two stages of the physical\ngelation process, separated by a temperature dependent crossover modulus: (i)\nan early nucleation regime during which rearrangements of the triple-helix CL\nplay a negligible role, (ii) a late, logarithmic aging one, which is preserved,\nthough slowed down, in the presence of irreversible CL. We show that aging is\nfully controlled by rearrangements and discuss the implication of our results\nin terms of the switch from an early, local dynamics to a late, cooperative\nlong-range one."
    },
    {
        "anchor": "Active nematic materials with substrate friction: Active turbulence in dense active systems is characterized by high vorticity\non a length scale that is large compared to that of individual entities. We\ndescribe the properties of active turbulence as momentum propagation is\nscreened by frictional damping. As friction is increased, the spacing between\nthe walls in the nematic director field decreases as a consequence of the more\nrapid velocity decays. This leads to, first, a regime with more walls and an\nincreased number of topological defects, and then to a jammed state in which\nthe walls deliminate bands of opposing flow, analogous to the shear bands\nobserved in passive complex fluids.",
        "positive": "Dual Role of Cell-Cell Adhesion In Tumor Suppression and Proliferation\n  Due to Collective Mechanosensing: It is known that mechanical interactions couple a cell to its neighbors,\nenabling a feedback loop to regulate tissue growth. However, the interplay\nbetween cell-cell adhesion strength, local cell density and force fluctuations\nin regulating cell proliferation is poorly understood. Here, we show that\nspatial variations in the tumor growth rates, which depend on the location of\ncells within tissue spheroids, are strongly influenced by cell-cell adhesion.\nAs the strength of the cell-cell adhesion increases, intercellular pressure\ninitially decreases, enabling dormant cells to more readily enter into a\nproliferative state. We identify an optimal cell-cell adhesion regime where\npressure on a cell is a minimum, allowing for maximum proliferation. We use a\ntheoretical model to validate this novel collective feedback mechanism coupling\nadhesion strength, local stress fluctuations and proliferation.Our results,\npredicting the existence of a non-monotonic proliferation behavior as a\nfunction of adhesion strength, are consistent with experimental results.\nSeveral experimental implications of the proposed role of cell-cell adhesion in\nproliferation are quantified, making our model predictions amenable to further\nexperimental scrutiny. We show that the mechanism of contact inhibition of\nproliferation, based on a pressure-adhesion feedback loop, serves as a unifying\nmechanism to understand the role of cell-cell adhesion in proliferation."
    },
    {
        "anchor": "Implementation of the Jager contact model for discrete element\n  simulations: In three-dimensional discrete element method (DEM) simulations, the particle\nmotions within a granular assembly can produce bewildering sequences of\nmovements at the contacts between particle pairs. With frictional contacts, the\nrelationship between contact movement and force is non-linear and\npath-dependent, requiring an efficient means of computing the forces and\nstoring their histories. By cleverly applying the principles of Cattaneo,\nMindlin, and Deresiewicz, Jurgen Jager developed an efficient approach for\ncomputing the full three-dimensional force between identical elastic spheres\nthat have undergone difficult movement sequences (J. Jager, New Solutions in\nContact Mechanics. WIT Press: Southampton, U.K.). This paper presents a\ncomplete Jager algorithm that can be incorporated into DEM codes and also\ndescribes three special provisions for DEM simulations: (1) a method for\nhandling particle pairs that undergo complex tumbling and twirling motions in\nthree-dimensions; (2) a compact data structure for storing the loading history\nof the many contacts in a large assembly; and (3) an approximation of the Jager\nalgorithm that reduces memory demand. The algorithm addresses contact\ntranslations between elastic spheres having identical properties, but it does\nnot resolve the tractions produced by twisting or rolling motions. A\nperformance test demonstrates that the algorithm can be applied in a DEM code\nwith modest increases in computation time but with more substantial increases\nin required storage.",
        "positive": "Phase separation dynamics of gluten protein mixtures: We investigate by time-resolved Synchrotron ultra-small X-ray scattering the\ndynamics of liquid-liquid phase-separation (LLPS) of gluten protein suspensions\nfollowing a temperature quench. Samples at a fixed concentration (237 mg/ml)\nbut with different protein compositions are investigated. In our experimental\nconditions, we show that fluid viscoelastic samples depleted in polymeric\nglutenin phase-separate following a spinodal decomposition process. We\nquantitatively probe the late stage coarsening that results from a competition\nbetween thermodynamics that speeds up the coarsening rate as the quench depth\nincreases, and transport that slows downs the rate. For even deeper quenches,\nthe even higher viscoelasticity of the continuous phase leads to a \"quasi\"\narrested phase separation. Anomalous phase-separation dynamics is by contrast\nmeasured for a gel sample rich in glutenin, due to elastic constraints. This\nwork illustrates the role of viscoelasticity in the dynamics of LLPS in protein\ndispersions."
    },
    {
        "anchor": "Resolving long-range spatial correlations in jammed colloidal systems\n  using photon correlation imaging: We introduce a new dynamic light scattering method, termed photon correlation\nimaging, which enables us to resolve the dynamics of soft matter in space and\ntime. We demonstrate photon correlation imaging by investigating the slow\ndynamics of a quasi two-dimensional coarsening foam made of highly packed,\ndeformable bubbles and a rigid gel network formed by dilute, attractive\ncolloidal particles. We find the dynamics of both systems to be determined by\nintermittent rearrangement events. For the foam, the rearrangements extend over\na few bubbles, but a small dynamical correlation is observed up to macroscopic\nlength scales. For the gel, dynamical correlations extend up to the system\nsize. These results indicate that dynamical correlations can be extremely\nlong-ranged in jammed systems and point to the key role of mechanical\nproperties in determining their nature.",
        "positive": "Topological transitions in evaporating thin films: A thin water film evaporating from a cleaved mica substrate undergoes a\nfirst-order phase transition between two values of film thickness. During\nevaporation, the interface between the two phases develops a fingering\ninstability similar to that observed in the Saffman-Taylor problem. The\ndynamics of the droplet interface is dictated by an infinite number of\nconserved quantities: all harmonic moments decay exponentially at the same\nrate. A typical scenario is the nucleation of a dry patch within the droplet\ndomain. We construct solutions of this problem and analyze the toplogical\ntransition occuring when the boundary of the dry patch meets the outer\nboundary. We show a duality between Laplacian growth and evaporation, and\nutilize it to explain the behaviour near the transition. We construct a family\nof problems for which evaporation and Laplacian growth are limiting cases and\nshow that a necessary condition for a smooth topological transition, in this\nfamily, is that all boundaries share the same pressure."
    },
    {
        "anchor": "Large-scale simulations of biological cell sorting driven by\n  differential adhesion follow diffusion-limited domain coalescence regime: Cell sorting, whereby a heterogeneous cell mixture segregates and forms\ndistinct homogeneous tissues, is one of the main collective cell behaviors at\nwork during development. Although differences in interfacial energies are\nrecognized to be a possible driving source for cell sorting, no clear consensus\nhas emerged on the kinetic law of cell sorting driven by differential adhesion.\nUsing a modified Cellular Potts Model algorithm that allows for efficient\nsimulations while preserving the connectivity of cells, we numerically explore\ncell-sorting dynamics over very large scales in space and time. For a binary\nmixture of cells surrounded by a medium, increase of domain size follows a\npower-law with exponent $n=1/4$ independently of the mixture ratio, revealing\nthat the kinetics is dominated by the diffusion and coalescence of rounded\ndomains. We compare these results with recent numerical studies on cell\nsorting, and discuss the importance of algorithmic differences as well as\nboundary conditions on the observed scaling.",
        "positive": "On the Modeling of Droplet Evaporation on Superhydrophobic Surfaces: When a drop of water is placed on a rough surface, there are two possible\nextreme regimes of wetting: the one called Cassie-Baxter (CB) with air pockets\ntrapped underneath the droplet and the one characterized by the homogeneous\nwetting of the surface, called the Wenzel (W) state. A way to investigate the\ntransition between these two states is by means of evaporation experiments, in\nwhich the droplet starts in a CB state and, as its volume decreases, penetrates\nthe surface's grooves, reaching a W state. Here we present a theoretical model\nbased on the global interfacial energies for CB and W states that allows us to\npredict the thermodynamic wetting state of the droplet for a given volume and\nsurface texture. We first analyze the influence of the surface geometric\nparameters on the droplet's final wetting state with constant volume, and show\nthat it depends strongly on the surface texture. We then vary the volume of the\ndroplet keeping fixed the geometric surface parameters to mimic evaporation and\nshow that the drop experiences a transition from the CB to the W state when its\nvolume reduces, as observed in experiments. To investigate the dependency of\nthe wetting state on the initial state of the droplet, we implement a cellular\nPotts model in three dimensions. Simulations show a very good agreement with\ntheory when the initial state is W, but it disagrees when the droplet is\ninitialized in a CB state, in accordance with previous observations which show\nthat the CB state is metastable in many cases. Both simulations and theoretical\nmodel can be modified to study other types of surface."
    },
    {
        "anchor": "Crystal nucleation as the ordering of multiple order parameters: Nucleation is an activated process in which the system has to overcome a free\nenergy barrier in order for a first-order phase transition between the\nmetastable and the stable phases to take place. In the liquid-to-solid\ntransition the process occurs between phases of different symmetry, and it is\nthus inherently a multi-dimensional process, in which all symmetries are broken\nat the transition. In this Focus Article, we consider some recent studies which\nhighlight the multi-dimensional nature of the nucleation process. Even for a\nsingle-component system, the formation of solid crystals from the metastable\nmelt involves fluctuations of two (or more) order parameters, often associated\nwith the decoupling of positional and orientational symmetry breaking. In other\nwords, we need at least two order parameters to describe the free-energy of a\nsystem including its liquid and crystalline states. This decoupling occurs\nnaturally for asymmetric particles or directional interactions, focusing here\non the case of water, but we will show that it also affects spherically\nsymmetric interacting particles, such as the hard-sphere system. We will show\nhow the treatment of nucleation as a multi-dimensional process has shed new\nlight on the process of polymorph selection, on the effect of external fields\non the nucleation process, and on glass-forming ability.",
        "positive": "Some simple results for the properties of polar fluids: The author's lecture notes concerning the correlation functions and the\nthermodynamics of a simple polar fluid are summarized. The emphasis is on the\ndipolar hard sphere fluid and the mean spherical approximation and on the\nrelation of these results to the Clausius-Mossotti and Onsager formulae for the\ndielectric constant. Previous excerpts from these lecture notes, Condens.\nMatter Phys., 2009, 12, 127; ibid., 2010, 13, 13002, have contained results\nthat were not widely known. It is hoped that this third, and likely final,\nexcerpt will prove equally helpful by gathering several results together and\nmaking these more widely available and recording a few new results."
    },
    {
        "anchor": "Flocking from a quantum analogy: Spin-orbit coupling in an active fluid: Systems composed of strongly interacting self-propelled particles can form a\nspontaneously flowing polar active fluid. The study of the connection between\nthe microscopic dynamics of a single such particle and the macroscopic dynamics\nof the fluid can yield insights into experimentally realizable active flows,\nbut this connection is well understood in only a few select cases. We introduce\na model of self-propelled particles based on an analogy with the motion of\nelectrons that have strong spin-orbit coupling. We find that, within our model,\nself-propelled particles are subject to an analog of the Heisenberg uncertainty\nprinciple that relates translational and rotational noise. Furthermore, by\ncoarse-graining this microscopic model, we establish expressions for the\ncoefficients of the Toner-Tu equations---the hydrodynamic equations that\ndescribe an active fluid composed of these \"active spins.\" The connection\nbetween self-propelled particles and quantum spins may help realize exotic\nphases of matter using active fluids via analogies with systems composed of\nstrongly correlated electrons.",
        "positive": "Micro-wires self-assembled and 3D-connected with the help of a nematic\n  liquid crystal: We discuss a method for producing automatic 3D connections at right places\nbetween substrates in front to one another. The idea is based on the\nmaterialization of disclination lines working as templates. The lines are first\ncreated in the nematic liquid crystal (5CB) at the very place where microwires\nhave to be synthesized. Due to their anchoring properties, colloids dispersed\ninto the nematic phase produce orientational distortions around them. These\ndistortions, which may be considered as due to topological charges, result in a\nnematic force, able to attract the colloids towards the disclinations.\nUltimately, the particles get trapped onto them, forming micro or\nnano-necklaces. Before being introduced in the nematic phase, the colloids are\ncovered with an adhering and conducting polypyrrole film directly synthesized\nat the surface of the particles (heterogeneous polymerization). In this manner,\nthe particles become conductive so that we may finally perform an\nelectropolymerization of pyrrole monomers solved in 5CB, and definitely stick\nthe whole necklace. The electric connection thus synthesized is analyzed by\nAFM, and its strength is checked by means of hydrodynamic tests. This wiring\nmethod could allow Moore's law to overcome the limitations that arise when\ndown-sizing the electronic circuits to nanometer scale."
    },
    {
        "anchor": "Scaling properties of granular rheology near the jamming transition: Rheological properties of a dense granular material consisting of\nfrictionless spheres are investigated. It is found that the shear stress, the\npressure, and the kinetic temperature obey critical scaling near the jamming\ntransition point, which is considered as a critical point. These scaling laws\nhave some peculiar properties in view of conventional critical phenomena\nbecause the exponents depend on the interparticle force models so that they are\nnot universal. It is also found that these scaling laws imply the relation\nbetween the exponents that describe the growing correlation length.",
        "positive": "Effects of multiple scattering on angle-independent structural color in\n  disordered colloidal materials: Disordered packings of colloidal spheres show angle-independent structural\ncolor when the particles are on the scale of the wavelength of visible light.\nPrevious work has shown that the positions of the peaks in the reflectance\nspectra can be predicted accurately from a single-scattering model that\naccounts for the effective refractive index of the material. This agreement\nshows that the main color peak arises from short-range correlations between\nparticles. However, the single-scattering model does not quantitatively\nreproduce the observed color: the main peak in the reflectance spectrum is much\nbroader and the reflectance at low wavelengths is much larger than predicted by\nthe model. We use a combination of experiment and theory to understand these\nfeatures. We find that one significant contribution to the breadth of the main\npeak is light that is scattered, totally internally reflected from the boundary\nof the sample, and then scattered again. The high reflectance at low\nwavelengths also results from multiple scattering but can be traced to the\nincrease in the scattering cross-section of individual particles with\ndecreasing wavelength. Both of these effects tend to reduce the saturation of\nthe structural color, which limits the use of these materials in applications.\nWe show that while the single-scattering model cannot reproduce the observed\nsaturations, it can be used to design materials in which multiple scattering is\nsuppressed and the color saturated, even in the absence of absorbing\ncomponents."
    },
    {
        "anchor": "Topological metric detects hidden order in disordered media: Recent advances in microscopy techniques make it possible to study the\ngrowth, dynamics, and response of complex biophysical systems at single-cell\nresolution, from bacterial communities to tissues and organoids. In contrast to\nordered crystals, it is less obvious how one can reliably distinguish two\namorphous yet structurally different cellular materials. Here, we introduce a\ntopological earth mover's (TEM) distance between disordered structures that\ncompares local graph neighborhoods of the microscopic cell-centroid networks.\nLeveraging structural information contained in the neighborhood motif\ndistributions, the TEM metric allows an interpretable reconstruction of\nequilibrium and non-equilibrium phase spaces and embedded pathways from static\nsystem snapshots alone. Applied to cell-resolution imaging data, the framework\nrecovers time-ordering without prior knowledge about the underlying dynamics,\nrevealing that fly wing development solves a topological optimal transport\nproblem. Extending our topological analysis to bacterial swarms, we find a\nuniversal neighborhood size distribution consistent with a Tracy-Widom law.",
        "positive": "On the mechanism responsible for unconventional thermal behaviour during\n  freezing: In this study, identical experiments of bottom-cooled solidification fluidic\nmixtures that exhibit faceted and dendritic microstructures were performed. The\nstrength of compositional convection was correlated with the solidifying\nmicrostructure morphology, with the help of separate Rayleigh numbers in the\nmushy and bulk-fluid zones. While the dendritic solidification experienced a\nmonotonic decrease in the bulk fluid temperature, solidification of the faceted\ncase revealed an unconventional, anomalous temperature rise in the bulk liquid,\nat the initiation of the eutectic phase. Based on the bulk-liquid temperature\nprofile, three distinct regimes of heat transfer were observed in the liquid\nover the course of solidification, namely - convection-dominated, transition,\nand conduction-dominated. The observations were analyzed and verified with the\nhelp of different initial compositions, as well as other mixtures that form\nfaceted morphology upon freezing. The observed temperature rise was further\nascertained by performing an energy balance in an indicative control volume\nahead of the solid-liquid interface. The plausible mechanism behind the gain in\ntemperature of the liquid during freezing was further generalized with the help\nof a simplified one-dimensional numerical model, and was extended to metals\nwhich are low Prandtl number mixtures. The study sheds new insights into the\nrole of microstrostructural morphology in governing the transport phenomena in\nthe bulk liquid."
    },
    {
        "anchor": "Anchoring-mediated stick-slip winding of cholesteric liquid crystals: The stick-slip phenomenon widely exists in contact mechanics, from the\nmacroscale to the nanoscale. During cholesteric-nematic unwinding by external\nfields, there is controversy regarding the role of planar surface anchoring,\nwhich may induce discontinuous stick-slip behaviors despite the well-known\ncontinuous transitions observed in past experiments. Here, we observe three\nregimes, namely constrained, stick-slip, and sliding-slip, under mechanical\nwinding with different anchoring conditions, and measure the responded forces\nby the Surface Force Balance. These behaviors result from a balance of\ncholesteric elastic torque and surface torque, reminiscent of the slip\nmorphology on frictional substrates [T. G. Sano et al., Phys. Rev. Lett. 118,\n178001 (2017)], and provide evidence of dynamics in static rotational friction.",
        "positive": "Oedometric Test, Bauer's Law and the Micro-Macro Connection for a Dry\n  Sand: What is the relationship between the macroscopic parameters of the\nconstitutive equation for a granular soil and the microscopic forces between\ngrains? In order to investigate this connection, we have simulated by molecular\ndynamics the oedometric compression of a granular soil (a dry and bad-graded\nsand) and computed the hypoplastic parameters $h_s$ (the granular skeleton\nhardness) and $\\eta$ (the exponent in the compression law) by following the\nsame procedure than in experiments, that is by fitting the Bauer's law $e/e0 =\nexp(-(3p/hs)\\eta)$, where $p$ is the pressure, and $e_0$ and $e$ are the\ninitial and present void ratios. The micro-mechanical simulation includes\nelastic and dissipative normal forces plus slip, rolling and static friction\nbetween grains. By this way we have explored how the macroscopic parameters\nchange by modifying the grains stiffness, V ; the dissipation coefficient,\n$\\gamma_n$; the static friction coefficient, $\\mu_s$; and the dynamic friction\ncoefficient, $\\mu_k$ . Cumulating all simulations, we obtained an unexpected\nresult: the two macroscopic parameters seems to be related by a power law, $h_s\n= 0.068(4)\\eta^{9.88(3)}$. Moreover, the experimental result for a Guamo sand\nwith the same granulometry fits perfectly into this power law. Is this relation\nreal? What is the final ground of the Bauer's Law? We conclude by exploring\nsome hypothesis."
    },
    {
        "anchor": "Dynamic control of speed and trajectories of active droplets in a\n  nematic environment by electric field and focused laser beam: One objective of active matter science is to unveil principles by which\nchaotic microscale dynamics could be transformed into useful work. A nematic\nliquid crystal environment offers a number of possibilities, one of which is a\ndirectional motion of an active droplet filled with an aqueous dispersion of\nswimming bacteria. In this work, using the responsiveness of the nematic to the\nelectric field and light, we demonstrate how to control the direction and speed\nof active droplets. The dielectric response of nematic to the electric field\ncauses two effects: (i) reorientation of the overall director, and (ii)\nchanging the symmetry of the director configuration around the droplet. The\nfirst effect redirects the propulsion direction while the second one changes\nthe speed. A laser beam pointed to the vicinity of the droplet can trigger the\ndesired director symmetry around the droplet, by switching between dipolar and\nquadrupolar configurations, thus affecting the motility and polarity of\npropulsion. The dynamic tuning of the direction and speed of active droplets\nrepresents a step forward in the development of controllable microswimmers.",
        "positive": "First-principles superadiabatic theory for the dynamics of inhomogeneous\n  fluids: For classical many-body systems subject to Brownian dynamics we develop a\nsuperadiabatic dynamical density functional theory (DDFT) for the description\nof inhomogeneous fluids out-of-equilibrium. By explicitly incorporating the\ndynamics of the inhomogeneous two-body correlation functions we obtain\nsuperadiabatic forces directly from the microscopic interparticle interactions.\nWe demonstrate the importance of these nonequilibrium forces for an accurate\ndescription of the one-body density by numerical implementation of our theory\nfor three-dimensional hard-spheres in a time-dependent planar potential. The\nrelaxation of the one-body density in superadiabatic-DDFT is found to be slower\nthan that predicted by standard adiabatic DDFT and significantly improves the\nagreement with Brownian dynamics simulation data. We attribute this improved\nperformance to the correct treatment of structural relaxation within the\nsuperadiabatic-DDFT. Our approach provides fundamental insight into the\nunderlying structure of dynamical density functional theories and makes\npossible the study of situations for which standard approaches fail."
    },
    {
        "anchor": "Determination of onset temperature from the entropy for fragile to\n  strong liquids: In this paper we establish a connection between the onset temperature of\nglassy dynamics with the change in the entropy for a wide range of model\nsystems.\n  We identify the crossing temperature of pair and excess entropies as the\nonset temperature. Below the onset temperature, the residual multiparticle\nentropy(RMPE), the difference between excess and pair entropies, becomes\npositive. The positive entropy can be viewed as equivalent to the larger phase\nspace exploration of the system. The new method of onset temperature prediction\nfrom entropy is less ambiguous, as it does not depend on any fitting parameter\nlike the existing methods. Our study also reveals the connection between\nfragility and the degree of breakdown of the Stokes Einstein (SE) relation.",
        "positive": "Adsorption isotherm and mechanism of $\\mathrm{Ca^{2+}}$ binding to\n  polyelectrolyte: Polyelectrolytes, such as polyacrylic acid (PAA), can effectively mitigate\n$\\mathrm{CaCO_3}$ scale formation. Despite their success as antiscalants, the\nunderlying mechanism of $\\mathrm{Ca^{2+}}$ binding to polyelectrolyte chains\nremains unresolved. Through all-atom molecular dynamics simulations, we\nconstruct an adsorption isotherm of $\\mathrm{Ca^{2+}}$ binding to sodium\npolyacrylate ($\\mathrm{NaPAA}$) and investigate the associated binding\nmechanism. We find that the number of calcium ions adsorbed\n$[\\mathrm{Ca^{2+}_{ads}}]$ to the polymer saturates at moderately high\nconcentrations of free calcium ions $[\\mathrm{Ca^{2+}_{aq}}]$ in the solution.\nThis saturation value is intricately connected with the binding modes\naccessible to $\\mathrm{Ca^{2+}}$ ions when they bind to the polyelectrolyte\nchain. We identify two dominant binding modes: the first involves binding to at\nmost two carboxylate oxygens on a polyacrylate chain, and the second, termed\nthe high binding mode, involves binding to four or more carboxylate oxygens. As\nthe concentration of free calcium ions $[\\mathrm{Ca^{2+}_{aq}}]$ increases from\nlow to moderate levels, the polyelectrolyte chain undergoes a conformational\ntransition from an extended coil to a hairpin-like structure, enhancing the\naccessibility to the high binding mode. At moderate concentrations of\n$[\\mathrm{Ca^{2+}_{aq}}]$, the high binding mode accounts for at least a third\nof all binding events. The chain's conformational change and its consequent\naccess to the high binding mode is found to increase the overall\n$\\mathrm{Ca^{2+}}$ ion binding capacity of the polyelectrolyte chain."
    },
    {
        "anchor": "Network evolution controlling strain-induced damage and self-healing of\n  elastomers with dynamic bonds: Highly stretchable and self-healable supramolecular elastomers are promising\nmaterials for future soft electronics, biomimetic systems, and smart textiles,\ndue to their dynamic cross-linking bonds. The dynamic or reversible nature of\nthe cross-links gives rise to interesting macroscopic responses in these\nmaterials such as self-healing and rapid stress-relaxation. However, the\nrelationship between bond activity and macroscopic mechanical response, and the\nself-healing properties of these dynamic polymer networks (DPNs) remains poorly\nunderstood. Using coarse-grained molecular dynamics (CGMD) simulations, we\nreveal a fundamental connection between the macroscopic behaviors of DPNs and\nthe shortest paths between distant nodes in the polymer network. Notably, the\ntrajectories of the material on the shortest path-strain map provide key\ninsights into understanding the stress-strain hysteresis, anisotropy, stress\nrelaxation, and self-healing of DPNs. Based on CGMD simulations under various\nloading histories, we formulate a set of empirical rules that dictate how the\nshortest path interacts with stress and strain. This lays the foundation for\nthe development of a physics-based theory centered around the non-local\nmicrostructural feature of shortest paths to predict the mechanical behavior of\nDPNs.",
        "positive": "Low density interior in supercooled aqueous nanodroplets expels ions to\n  the subsurface: The interaction between water and ions within droplets plays a key role in\nthe chemical reactivity of atmospheric and man-made aerosols. Here we report\ndirect computational evidence that in supercooled aqueous nanodroplets a lower\ndensity core of tetrahedrally coordinated water expels the cosmotropic ions to\nthe denser and more disordered subsurface. In contrast, at room temperature,\ndepending on the nature of the ion the radial distribution in the droplet core\nis nearly uniform or elevated towards the center. We analyze the spatial\ndistribution of a single ion in terms of a reference electrostatic model. The\nenergy of the system in the analytical model is expressed as the sum of the\nelectrostatic and surface energy of a deformable droplet. The model predicts\nthat the ion is subject to a harmonic potential centered at the droplet's\ncenter of mass. We name this effect \"electrostatic confinement\". The model's\npredictions are consistent with the simulation findings for a single ion at\nroom temperature but not at supercooling. We anticipate this study to be the\nstarting point for investigating the structure of supercooled (electro)sprayed\ndroplets that are used to preserve the conformations of macromolecules\noriginating from the bulk solution."
    },
    {
        "anchor": "Design principles for Bernal spirals and helices with tunable pitch: Using the framework of potential energy landscape theory, we describe two in\nsilico designs for self-assembling helical colloidal superstructures based upon\ndipolar dumbbells and Janus-type building blocks, respectively. Helical\nsuperstructures with controllable pitch length are obtained using external\nmagnetic field driven assembly of asymmetric dumbbells involving screened\nelectrostatic as well as magnetic dipolar interactions. The pitch of the helix\nis tuned by modulating the Debye screening length over an experimentally\naccessible range. The second design is based on building blocks composed of\nrigidly linked spheres with short-range anisotropic interactions, which are\npredicted to self-assemble into Bernal spirals. These spirals are quite\nflexible, and longer helices undergo rearrangements via cooperative, hinge-like\nmoves, in agreement with experiment.",
        "positive": "Digital video microscopy enhanced by deep learning: Single particle tracking is essential in many branches of science and\ntechnology, from the measurement of biomolecular forces to the study of\ncolloidal crystals. Standard current methods rely on algorithmic approaches: by\nfine-tuning several user-defined parameters, these methods can be highly\nsuccessful at tracking a well-defined kind of particle under low-noise\nconditions with constant and homogenous illumination. Here, we introduce an\nalternative data-driven approach based on a convolutional neural network, which\nwe name DeepTrack. We show that DeepTrack outperforms algorithmic approaches,\nespecially in the presence of noise and under poor illumination conditions. We\nuse DeepTrack to track an optically trapped particle under very noisy and\nunsteady illumination conditions, where standard algorithmic approaches fail.\nWe then demonstrate how DeepTrack can also be used to track multiple particles\nand non-spherical objects such as bacteria, also at very low signal-to-noise\nratios. In order to make DeepTrack readily available for other users, we\nprovide a Python software package, which can be easily personalized and\noptimized for specific applications."
    },
    {
        "anchor": "Non-Equilibrium Thermodynamics of Self-Replicating Protocells: We provide a non-equilibrium thermodynamic description of the life-cycle of a\ndroplet based, chemically feasible, system of protocells. By coupling the\nprotocells metabolic kinetics with its thermodynamics, we demonstrate how the\nsystem can be driven out of equilibrium to ensure protocell growth and\nreplication. This coupling allows us to derive the equations of evolution and\nto rigorously demonstrate how growth and replication life-cycle can be\nunderstood as a non-equilibrium thermodynamic cycle. The process does not\nappeal to genetic information or inheritance, and is based only on\nnon-equilibrium physics considerations. Our non-equilibrium thermodynamic\ndescription of simple, yet realistic, processes of protocell growth and\nreplication, represents an advance in our physical understanding of a central\nbiological phenomenon both in connection to the origin of life and for modern\nbiology.",
        "positive": "Compression and stretching of a self-avoiding chain in cylindrical\n  nanopores: Force-induced deformations of a self-avoiding chain confined inside a\ncylindrical cavity, with diameter $D$, are probed using molecular dynamics\nsimulations, scaling analysis, and analytical calculations. We obtain and\nconfirm a simple scaling relation $-f \\cdot D \\sim R^{-9/4}$ in the\nstrong-compression regime, while for weak deformations we find $f \\cdot D =\n-A(R/R_0) + B (R/R_0)^{-2}$, where $A$ and $B$ are constants, $f$ the external\nforce, and $R$ the chain extension (with $R_0$ its unperturbed value). For a\nstrong stretch, we present a universal, analytical force-extension relation.\nOur results can be used to analyze the behavior of biomolecules in confinement."
    },
    {
        "anchor": "Minima of shear viscosity and thermal conductivity coefficients of\n  classical fluids: The shear viscosity and thermal conductivity coefficients of various liquids\nexhibit minima along certain trajectories on the phase diagram. These minima\narise due to the crossover between the momentum and energy transport mechanisms\nin gas-like and liquid-like regimes. We demonstrate that the magnitudes of the\nminima are quasi-universal in appropriately reduced units, especially for the\nviscosity coefficients. Results presented in support of this observation\nconcern the transport properties of three simple model systems with different\npairwise interaction potentials (hard spheres, Lennard-Jones, and Coulomb) as\nwell as seven important real atomic and molecular liquids (Ne, Ar, Kr, Xe,\nCH$_4$, CO$_2$, and N$_2$). The minima in viscosity and thermal conductivity\nrepresent useful reference points for fluid transport properties.",
        "positive": "Collective Motion in the Interfacial and Interior Regions of Supported\n  Polymer Films and its Relation to Relaxation: To understand the role of collective motion in the often large changes in\ninterfacial molecular mobility observed in polymer films, we investigate the\nextent of collective motion in the interfacial regions of a thin supported\npolymer film and within the film interior by molecular dynamics simulation.\nContrary to commonly stated expectations, we find that the extent of collective\nmotion, as quantified by string-like molecular exchange motion, is similar in\nmagnitude in polymer-air interfacial layer to that in the film interior, and\nboth are generally distinct from the bulk material. This finding is consistent\nwith Adam-Gibbs description of the segmental dynamics within mesoscopic film\nregions where the extent of collective motion is related to the configurational\nentropy of the film as whole rather than a locally defined extent of collective\nmotion or configurational entropy."
    },
    {
        "anchor": "Elastic stresses reverse Ostwald ripening: When liquid droplets nucleate and grow in a polymer network, compressive\nstresses can significantly increase their internal pressure, reaching values\nthat far exceed the Laplace pressure. When droplets have grown in a polymer\nnetwork with a stiffness gradient, droplets in relatively stiff regions of the\nnetwork tend to dissolve, favoring growth of droplets in softer regions. Here,\nwe show that this elastic ripening can be strong enough to reverse the\ndirection of Ostwald ripening: large droplets can shrink to feed the growth of\nsmaller ones. To numerically model these experiments, we generalize the theory\nof elastic ripening to account for gradients in solubility alongside gradients\nin mechanical stiffness.",
        "positive": "Entropic force of cone-tethered polymers interacting with a planar\n  surface: Computer simulations are used to characterize the entropic force of one or\nmore polymers tethered to the tip of a hard conical object that interact with a\nnearby hard flat surface. Pruned-enriched-Rosenbluth-method (PERM) Monte Carlo\nsimulations are used to calculate the variation of the conformational free\nenergy, $F$, of a hard-sphere polymer with respect to cone-tip-to-surface\ndistance, $h$, from which the variation of the entropic force, $f\\equiv\n|dF/dh|$, with $h$ is determined. We consider the following cases: (1) a single\nfreely-jointed tethered chain, (2) a single semiflexible tethered chain, and\n(3) several freely-jointed chains of equal length each tethered to the cone\ntip. The simulation results are used to test the validity of a prediction by\nMaghrebi et al. (EPL, 96, 66002(2011); Phys. Rev. E 86, 061801 (2012)) that\n$f\\propto (\\gamma_\\infty-\\gamma_0) h^{-1}$, where $\\gamma_0$ and\n$\\gamma_\\infty$ are universal scaling exponents for the partition function of\nthe tethered polymer for $h=0$ and $h=\\infty$, respectively. The measured\nfunctions $f(h)$ are generally consistent with the predictions, with small\nquantitative discrepancies arising from the approximations employed in the\ntheory. In the case of multiple tethered polymers, the entropic force per\npolymer is roughly constant, which is qualitatively inconsistent with the\npredictions."
    },
    {
        "anchor": "Perspective: Nonequilibrium glassy dynamics in dense systems of active\n  particles: Despite the diversity of materials designated as active matter, virtually all\nactive systems undergo a form of dynamic arrest when crowding and activity\ncompete, reminiscent of the dynamic arrest observed in colloidal and molecular\nfluids undergoing a glass transition. We present a short perspective on recent\nand ongoing efforts to understand how activity competes with other physical\ninteractions in dense systems. We first review recent experimental work on\nactive materials that uncovered both classic signatures of glassy dynamics and\nintriguing novel phenomena at large density. We introduce a minimal model of\nself-propelled particles where the competition between interparticle\ninteractions, crowding, and self-propulsion can be studied in great detail. We\ndiscuss more complex models that include some additional, material-specific\ningredients. We end with some general perspectives on dense active materials,\nsuggesting directions for future research, in particular for theoretical work.",
        "positive": "Understanding the dynamics of biological colloids to elucidate cataract\n  formation towards the development of methodology for its early diagnosis: The eye lens is the most characteristic example of mammalian tissues\nexhibiting complex colloidal behaviour. In this paper we briefly describe how\ndynamics in colloidal suspensions can help addressing selected aspects of lens\ncataract which is ultimately related to the protein self-assembly under\npathological conditions. Results from dynamic light scattering of eye lens\nhomogenates over a wide protein concentration were analyzed and the various\nrelaxation modes were identified in terms of collective and self-diffusion\nprocesses. Using this information as an input, the complex relaxation pattern\nof the intact lens nucleus was rationalized. The model of cold cataract - a\nphase separation effect of the lens cytoplasm with cooling - was used to\nsimulate lens cataract at in vitro conditions in an effort to determine the\nparameters of the correlation functions that can be used as reliable indicators\nof the cataract onset. The applicability of dynamic light scattering as a\nnon-invasive, early-diagnostic tool for ocular diseases is also demonstrated in\nthe light of the findings of the present paper."
    },
    {
        "anchor": "Vapor-deposited non-crystalline phase vs ordinary glasses and\n  supercooled liquids: evidence for significant thermodynamic and kinetic\n  differences: Vapor deposition of molecules on a substrate often results in glassy\nmaterials of high kinetic stability and low enthalpy. The extraordinary\nproperties of such glasses are attributed to high rates of surface diffusion\nduring sample deposition, which makes it possible for constituents to find a\nconfiguration of much lower energy on a typical laboratory time scale1,2,7. The\nexact structure of the resulting phase is often assumed to be identical to that\nobtained by aging of ordinary glass over exceedingly long times. Using Fast\nScanning Calorimetry technique, we show that out-of-equilibrium relaxation\nkinetics and possibly the enthalpy of vapor-deposited films of toluene, an\narchetypical fragile glass former, are distinct from those of ordinary\nsupercooled phase even when the deposition takes place at temperatures above\nthe glass softening. These observations provide support to the conjecture that\nthe vapor-deposition may result in formation of non-crystalline phase of unique\nstructural, thermodynamic, and kinetic properties.",
        "positive": "Lattice BGK kinetic model for high speed compressible flows:\n  hydrodynamic and nonequilibrium behaviors: We present a simple and general approach to formulate the lattice BGK model\nfor high speed compressible flows. The main point consists of two parts: an\nappropriate discrete equilibrium distribution function (DEDF) $\\mathbf{f}^{eq}$\nand a discrete velocity model with flexible velocity size. The DEDF is obtained\nby $\\mathbf{f}^{eq}=\\mathbf{C}^{-1}\\mathbf{M}$, where $\\mathbf{M}$ is a set of\nmoment of the Maxwellian distribution function, and $\\mathbf{C}$ is the matrix\nconnecting the DEDF and the moments. The numerical components of $\\mathbf{C}$\nare determined by the discrete velocity model. The calculation of\n$\\mathbf{C}^{-1}$ is based on the analytic solution which is a function of the\nparameter controlling the sizes of discrete velocity. The choosing of discrete\nvelocity model has a high flexibility. The specific heat ratio of the system\ncan be flexible. The approach works for the one-, two- and three-dimensional\nmodel constructions. As an example, we compose a new lattice BGK kinetic model\nwhich works not only for recovering the Navier-Stokes equations in the\ncontinuum limit but also for measuring the departure of system from its\nthermodynamic equilibrium. Via adjusting the sizes of the discrete velocities\nthe stably simulated Mach number can be significantly increased up to 30 or\neven higher. The model is verified and validated by well-known benchmark tests.\nSome macroscopic behaviors of the system due to deviating from thermodynamic\nequilibrium around the shock wave interfaces are shown."
    },
    {
        "anchor": "Heat diffusion related damping process in highly precise coarse-grained\n  model for SWCNT's nonlinearity: Second sound and heat diffusion in single-walled carbon nanotubes (SWCNT) is\nwell-known phenomena which is related to the high thermal conductivity of this\nmaterial. In this paper, we have shown that the heat diffusion along the tube\naxis affects the macroscopic motion of SWCNT and adapting this phenomena to\ncoarse-grained model can improve the precision of the coarse-grained molecular\ndynamics (CGMD) exceptionally. The nonlinear macroscopic motion of SWCNT in the\nfree thermal vibration condition in adiabatic environment is demonstrated in\nthe most simplified version of CG modeling as maintaining finite temperature\nand total energy with suggested dissipation process derived from internal heat\ndiffusion. The internal heat diffusion related to the cross correlated momentum\nfrom different potential energy functions is considered, and it can reproduce\nthe nonlinear dynamic nature of SWCNTs without external thermostatting in CG\nmodel. Memory effect and thermostat with random noise distribution are not\nincluded, and the effect of heat diffusion on memory effect is reviewed through\nMori-Zwanzig formalism. This diffusion shows perfect syncronization of the\nmotion between that of CGMD and MD simulation, which is started with initial\nconditions from the molecular dynamics (MD) simulation. The heat diffusion\nrelated to this process has shown the same dispersive characteristics to second\nwave in SWCNT. This replication with good precision indicates that the internal\nheat diffusion process is the essential cause of the nonlinearity of the tube.\nThe nonlinear dynamic characteristics from the various scale of simple beads\nsystems are examined with expanding its time step and node length\nsimultaneously.",
        "positive": "Influence of mechanical properties on mixing and segregation of granular\n  material: Processes of mixing and segregation in a packed bed of granular material\nstirred by a periodically moving rectangular bar are simulated by the discrete\nelement method (DEM). Influence of mechanical properties of the particle\nmaterial (dynamic friction coefficient, density, elastic modulus) on the\nsegregation intensity is researched. Dynamic friction coefficient was found to\nhave the most noticeable influence to the segregation intensity."
    },
    {
        "anchor": "2D versus 3D Freezing of a Lennard-Jones Fluid in a Slit Pore: A\n  Molecular Dynamics Study: We present a computer simulation study of a (6,12)-Lennard-Jones fluid\nconfined to a slit pore, formed by two uniform planes. These interact via\n(3,9)-Lennard-Jones potential with the fluid particles. When the fluid\napproaches the liquid-to-solid transition we first observe layering parallel to\nthe walls. In order to investigate the nature of the freezing transition we\nperformed a detailed analysis of the bond-orientational order parameter in the\nlayers. We found no signs of hexatic order which would indicate a melting\nscenario of the Kosterlitz-Thouless type. An analysis of the mean-square\ndisplacement shows that the particles can easily move between the layers,\nmaking the crystallization a 3d-like process. This is consistent with the fact\nthat we observe a considerable hysteresis in the heating-freezing curves,\nshowing that the crystallization transition proceeds as an activated process.",
        "positive": "GPU Based Detection of Topological Changes in Voronoi Diagrams: The Voronoi diagrams are an important tool having theoretical and practical\napplications in a large number of fields. We present a new procedure,\nimplemented as a set of CUDA kernels, which detects, in a general and efficient\nway, topological changes in case of dynamic Voronoi diagrams whose generating\npoints move in time. The solution that we provide has been originally developed\nto identify plastic events during simulations of soft-glassy materials based on\na Lattice Boltzmann model with frustrated-short range attractive and\nmid/long-range repulsive-interactions. Along with the description of our\napproach, we present also some preliminary physics results."
    },
    {
        "anchor": "Tension dynamics and viscoelasticity of extensible wormlike chains: The dynamic response of prestressed semiflexible biopolymers is characterized\nby the propagation and relaxation of tension, which arises due to the near\ninextensibility of a stiff backbone. It is coupled to the dynamics of contour\nlength stored in thermal undulations, but also to the local relaxation of\nelongational strain. We present a systematic theory of tension dynamics for\nstiff yet extensible wormlike chains. Our results show that even moderate\nprestress gives rise to distinct Rouse-like extensibility signatures in the\nhigh-frequency viscoelastic response.",
        "positive": "Dynamics of flowing 2D skyrmions: We investigate, numerically, the effects of externally imposed material flows\non the structure and temporal evolution of liquid crystal skyrmions. The\ndynamics of a 2D system of skyrmions is modeled using the Ericksen-Leslie\ntheory, which is based on two coupled equations, one for material flow and the\nother for the director field. As the time scales of the velocity and director\nfields differ by several orders of magnitude for realistic values of the system\nparameters, we have simplified the calculations by assuming that the velocity\nrelaxes instantaneously when compared to the relaxation of the director field.\nThus, we have used a finite-differences method known as artificial\ncompressibility with adaptive time step to solve the velocity field and a\nfourth-order Runge-Kutta method for the director field. We characterized the\nskyrmion shape or configuration as a function of the time and the average\nvelocity of the flow field. We found that for velocities above a certain\nthreshold, the skyrmions stretch in the direction perpendicular to the flow, by\ncontrast to the regime of weak flows where the skyrmions stretch along the\nstreamlines of the flow field. These two regimes are separated by an abrupt\n(first-order) dynamical transition, which is robust with respect to e.g., the\nliquid crystal elastic anisotropy. Additionally, we have found how the presence\nof a second skyrmion affects the evolution of the shape of the skyrmions, by\ncomparing the evolution of pairs of skyrmions to the evolution of a\nsingle-skyrmion."
    },
    {
        "anchor": "Experimental study of random close packed colloidal particles: A collection of spherical particles can be packed tightly together into an\namorphous packing known as \"random close packing\" (RCP). This structure is of\ninterest as a model for the arrangement of molecules in simple liquids and\nglasses, as well as the arrangement of particles in sand piles. We use confocal\nmicroscopy to study the arrangement of colloidal particles in an experimentally\nrealized RCP state. We image a large volume containing more than 450,000\nparticles with a resolution of each particle position to better than 0.02\nparticle diameters. While the arrangement of the particles satisfies multiple\ncriteria for being random, we also observe a small fraction (less than 3%) of\ntiny crystallites (4 particles or fewer). These regions pack slightly better\nand are thus associated with locally higher densities. The structure factor of\nour sample at long length scales is non-zero, $S(0) \\approx 0.049$, suggesting\nthat there are long wavelength density fluctuations in our sample, perhaps due\nto the tiny crystallites. Our results suggest that experimentally realizable\nRCP systems may be different from simulated RCP systems, in particular, with\nthe presence of these long wavelength density fluctuations.",
        "positive": "Liquids more stable than crystals: All liquids (except helium due to quantum effects) crystallize at low\ntemperatures, forming ordered structures. The competition between disorder,\nwhich stabilizes the liquid phase, and energy, which favors the ordered\ncrystalline structure, inevitably turns in favor of the latter when temperature\nis lowered and the entropic contribution to the free energy becomes\nprogressively less and less relevant. The \"liquid\" state survives at low\ntemperatures only as a glass, an out-of-equilibrium arrested state of matter.\nThis textbook description holds inevitably for atomic and molecular systems,\nwhere the interaction between particles is set by quantum mechanical laws. The\nquestion remains whether the same physics hold for colloidal particles, where\ninter-particle interactions are usually short-ranged and tunable. Here we show\nthat for patchy colloids with limited valence, conditions can be found for\nwhich the disordered liquid phase is stable all the way down to the\nzero-temperature limit. Our results offer interesting cues for understanding\nthe stability of gels and the glass forming ability of atomic and molecular\nnetwork glasses."
    },
    {
        "anchor": "Structure-dynamics relationship in ratcheted colloids: Resonance\n  melting, dislocations, and defect clusters: We consider a two dimensional colloidal dispersion of soft-core particles\ndriven by a one dimensional stochastic flashing ratchet that induces a time\naveraged directed particle current through the system. It undergoes a\nnon-equilibrium melting transition as the directed current approaches a maximum\nassociated with a resonance of the ratcheting frequency with the relaxation\nfrequency of the system. We use extensive molecular dynamics simulations to\npresent a detailed phase diagram in the ratcheting rate-mean density plane.\nWith the help of numerically calculated structure factor, solid and hexatic\norder parameters, and pair correlation functions, we show that the\nnon-equilibrium melting is a continuous transition from a quasi-long ranged\nordered solid to a hexatic phase. The transition is mediated by the unbinding\nof dislocations, and formation of compact and string-like defect clusters.",
        "positive": "Capillary fracture of soft gels: A liquid droplet resting on a soft gel substrate can deform that substrate to\nthe point of material failure, whereby fractures develop on the gel surface\nthat propagate outwards from the contact-line in a starburst pattern. In this\npaper, we characterize i) the initiation process in which the number of arms in\nthe starburst is controlled by the ratio of surface tension contrast to the\ngel's elastic modulus and ii) the propagation dynamics showing that once\nfractures are initiated they propagate with a universal power law $L\\propto\nt^{3/4}$. We develop a model for crack initiation by treating the gel as a\nlinear elastic solid and computing the deformations within the substrate from\nthe liquid/solid wetting forces. The elastic solution shows that both the\nlocation and magnitude of the wetting forces are critical in providing a\nquantitative prediction for the number of fractures and, hence, an\ninterpretation of the initiation of capillary fractures. This solution also\nreveals that the depth of the gel is an important factor in the fracture\nprocess, as it can help mitigate large surface tractions; this finding is\nconfirmed with experiments. We then develop a model for crack propagation by\nconsidering the transport of an inviscid fluid into the fracture tip of an\nincompressible material, and find that a simple energy-conservation argument\ncan explain the observed material-independent power law. We compare predictions\nfor both linear elastic and neo-Hookean solids finding that the latter better\nexplains the observed exponent."
    },
    {
        "anchor": "Scale invariant pattern in dynamically extending lattice: We study the implications of coupling Langmuir kinetics (LK) process with the\ndynamics of an extending lattice. The model that we consider couples\ndynamically extending exclusion process (DEEP) with the process of random\nattachment and detachment of particles in the bulk of the lattice. We explore a\ndynamical regime where the boundary processes of lattice extension and particle\ninput compete with the bulk process of particle attachment and detachment. This\ncompetition leads to scale invariant density profile of particles when\nexpressed in terms of the relative position in the growing lattice. It also\nleads to phase coexistence and shocks in the bulk of the lattice. We use a\ncombination of Mean Field (MF) analysis and Monte Carlo simulations to\ncharacterize the density profile in growing lattice and construct a MF phase\ndiagram. This study will have possible implications for transport and\npatterning in growing fungal filament.",
        "positive": "Yielding and bifurcated aging in nanofibrillar networks: The yielding of disordered materials is a complex transition involving\nsignificant changes of the material's microstructure and dynamics. After\nyielding, many soft materials recover their quiescent properties over time as\nthey age. There remains, however, a lack of understanding of the nature of this\nrecovery. Here, we elucidate the mechanisms by which fibrillar networks restore\ntheir ability to support stress after yielding. Crucially, we observe that the\naging response bifurcates around a critical stress $\\sigma_\\mathrm{c}$, which\nis equivalent to the material yield stress. After an initial yielding event,\nfibrillar networks subsequently yield faster and at lower magnitudes of stress.\nFor stresses $\\sigma<\\sigma_\\mathrm{c}$, the time to yielding increases with\nwaiting time $t_\\mathrm{w}$ and diverges once the network has restored\nsufficient entanglement density to support the stress. When $\\sigma >\n\\sigma_\\mathrm{c}$, the yield time instead plateaus at a finite value because\nthe developed network density is insufficient to support the applied stress. We\nquantitatively relate the yielding and aging behavior of the network to the\ncompetition between stress-induced disentanglement and dynamic fluctuations of\nthe fibrils rebuilding the network. The bifurcation in the material response\naround $\\sigma_c$ provides a new possibility to more rigorously localize the\nyield stress in disordered materials with time-dependent behavior."
    },
    {
        "anchor": "Scalable Surface Area Characterization by Electrokinetic Analysis of\n  Complex Anion Adsorption: By means of the in situ electrokinetic assessment of aqueous particles in\nconjunction with the addition of anionic adsorbates, we develop and examine a\nnew approach to the scalable characterization of the specific accessible\nsurface area of particles in water. For alumina powders of differing morphology\nin mildly acidic aqueous suspensions, the effective surface charge was modified\nby carboxylate anion adsorption through the incremental addition of oxalic and\ncitric acids. The observed zeta potential variation as a function of the\nproportional reagent additive was found to exhibit inverse hyperbolic sine-type\nbehavior predicted to arise from monolayer adsorption following the\nGrahame-Langmuir model. Through parameter optimization by inverse problem\nsolving, the zeta potential shift with relative adsorbate addition revealed a\nnearly linear correlation of a defined surface-area-dependent parameter with\nthe conventionally measured surface area values of the powders, demonstrating\nthat the proposed analytical framework is applicable for the in situ surface\narea characterization of aqueous particulate matter. The investigated methods\nhave advantages over some conventional surface analysis techniques owing to\ntheir direct applicability in aqueous environments at ambient temperature and\nthe ability to modify analysis scales by variation of the adsorption cross\nsection.",
        "positive": "Nonlinear atom optics and bright gap soliton generation in finite\n  optical lattices: We theoretically investigate the transmission dynamics of coherent matter\nwave pulses across finite optical lattices in both the linear and the nonlinear\nregimes. The shape and the intensity of the transmitted pulse are found to\nstrongly depend on the parameters of the incident pulse, in particular its\nvelocity and density: a clear physical picture for the main features observed\nin the numerical simulations is given in terms of the atomic band dispersion in\nthe periodic potential of the optical lattice. Signatures of nonlinear effects\ndue the atom-atom interaction are discussed in detail, such as atom optical\nlimiting and atom optical bistability. For positive scattering lengths, matter\nwaves propagating close to the top of the valence band are shown to be subject\nto modulational instability. A new scheme for the experimental generation of\nnarrow bright gap solitons from a wide Bose-Einstein condensate is proposed:\nthe modulational instability is seeded in a controlled way starting from the\nstrongly modulated density profile of a standing matter wave and the solitonic\nnature of the generated pulses is checked from their shape and their\ncollisional properties."
    },
    {
        "anchor": "Mechanochemical induction of wrinkling morphogenesis on elastic shells: Morphogenetic dynamics of tissue sheets require coordinated cell shape\nchanges regulated by global patterning of mechanical forces. Inspired by such\nbiological phenomena, we propose a minimal mechanochemical model based on the\nnotion that cell shape changes are induced by diffusible biomolecules that\ninfluence tissue contractility in a concentration-dependent manner -- and whose\nconcentration is in turn affected by the macroscopic tissue shape. We perform\ncomputational simulations of thin shell elastic dynamics to reveal propagating\nchemical and three-dimensional deformation patterns arising due to a sequence\nof buckling instabilities. Depending on the concentration threshold that\nactuates cell shape change, we find qualitatively different patterns. The\nmechanochemically coupled patterning dynamics are distinct from those driven by\npurely mechanical or purely chemical factors. Using numerical simulations and\ntheoretical arguments, we analyze the elastic instabilities that result from\nour model and provide simple scaling laws to identify wrinkling morphologies.",
        "positive": "Geometry underlies the mechanical stiffening and softening of an\n  indented floating film: A basic paradigm underlying the Hookean mechanics of amorphous, isotropic\nsolids is that small deformations are proportional to the magnitude of external\nforces. However, slender bodies may undergo large deformations even under\nminute forces, leading to nonlinear responses rooted in purely geometric\neffects. Here we study the indentation of a polymer film on a liquid bath. Our\nexperiments and simulations support a recently-predicted stiffening response\n[Vella & Davidovitch, Phys. Rev. E 98, 013003 (2018)], and we show that the\nsystem softens at large slopes, in agreement with our theory that addresses\nsmall and large deflections. We show how stiffening and softening emanate from\nnontrivial yet generic features of the stress and displacement fields."
    },
    {
        "anchor": "Surfing its own wave: hydroelasticity of a particle near a membrane: We show using theory and experiments that a small particle moving along an\nelastic membrane through a viscous fluid is repelled from the membrane due to\nhydro-elastic forces. The viscous stress field produces an elastic disturbance\nleading to particle-wave coupling. We derive an analytic expression for the\nparticle trajectory in the lubrication limit, bypassing the construction of the\ndetailed velocity and pressure fields. The normal force is quadratic in the\nparallel speed, and is a function of the tension and bending resistance of the\nmembrane. Experimentally, we measure the normal displacement of spheres\nsedimenting along an elastic membrane and find quantitative agreement with the\ntheoretical predictions with no fitting parameters. We experimentally\ndemonstrate the effect to be strong enough for particle separation and sorting.\nWe discuss the significance of these results for bio-membranes and propose our\nmodel for membrane elasticity measurements.",
        "positive": "Single-molecule experiments in biological physics: methods and\n  applications: I review single-molecule experiments (SME) in biological physics. Recent\ntechnological developments have provided the tools to design and build\nscientific instruments of high enough sensitivity and precision to manipulate\nand visualize individual molecules and measure microscopic forces. Using SME it\nis possible to: manipulate molecules one at a time and measure distributions\ndescribing molecular properties; characterize the kinetics of biomolecular\nreactions and; detect molecular intermediates. SME provide the additional\ninformation about thermodynamics and kinetics of biomolecular processes. This\ncomplements information obtained in traditional bulk assays. In SME it is also\npossible to measure small energies and detect large Brownian deviations in\nbiomolecular reactions, thereby offering new methods and systems to scrutinize\nthe basic foundations of statistical mechanics. This review is written at a\nvery introductory level emphasizing the importance of SME to scientists\ninterested in knowing the common playground of ideas and the interdisciplinary\ntopics accessible by these techniques. The review discusses SME from an\nexperimental perspective, first exposing the most common experimental\nmethodologies and later presenting various molecular systems where such\ntechniques have been applied. I briefly discuss experimental techniques such as\natomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers\n(MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I\nthen present several applications of SME to the study of nucleic acids (DNA,\nRNA and DNA condensation), proteins (protein-protein interactions, protein\nfolding and molecular motors). Finally, I discuss applications of SME to the\nstudy of the nonequilibrium thermodynamics of small systems and the\nexperimental verification of fluctuation theorems. I conclude with a discussion\nof open questions and future perspectives."
    },
    {
        "anchor": "Solvation Effects in Phase Transitions in Soft Matter: Phase transitions in polar binary mixtures can be drastically altered even by\na small amount of salt. This is because the preferential solvation strongly\ndepends on the ambient composition. Together with a summary of our research in\nthis problem, we present some detailed results on the role of antagonistic salt\ncomposed of hydrophilic and hydrophobic ions. These ions tend to segregate at\nliquid-liquid interfaces and selectively couple to water-rich and oil-rich\ncomposition fluctuations, leading to mesophase formation. In our\ntwo-dimensional simulation, the corasening of the domain structures can be\nstopped or slowed down, depending on the interaction parameter (or the\ntemperature) and the salt density. We realize stripe patterns at the critical\ncomposition and droplet patterns at off-critical compositions. In the latter\ncase, charged droplets emerge with considerable size dispersity in a percolated\nregion. We also give the structure factors among the ions, accounting for the\nCoulomb interaction and the solvation interaction mediated by the composition\nfluctuations.",
        "positive": "Wall-anchored semiflexible polymer under large amplitude oscillatory\n  shear flow: The properties of semiflexible polymers tethered by one end to an\nimpenetrable wall and exposed to oscillatory shear flow are investigated by\nmesoscale simulations. A polymer, confined in two dimensions, is described by a\nlinear bead-spring chain, and fluid interactions are incorporated by the\nBrownian multiparticle collision dynamics approach. At small strains, the\npolymers follow the applied flow field. However, at high strain, we find a\nstrongly nonlinear response, with major conformational changes. Polymers are\nstretched along the flow direction and exhibit U-shaped conformations while\nfollowing the flow. As a consequence of confinement in the half-space, a\nfrequency doubling in the time-dependent polymer properties appears along the\ndirection normal to the wall."
    },
    {
        "anchor": "From adhesion to wetting of a soft particle: Using a thermodynamical approach, we calculate the deformation of a spherical\nelastic particle placed on a rigid substrate, under zero external load, and\nincluding an ingredient of importance in soft matter: the interfacial tension\nof the cap. In a first part, we limit the study to small deformation. In\ncontrast with previous works, we obtain an expression for the energy that\nprecisely contains the JKR and Young-Dupr\\'e asymptotic regimes, and which\nestablishes a continuous bridge between them. In a second part, we consider the\nlarge deformation case, which is relevant for future comparison with numerical\nsimulations and experiments on very soft materials. Using a fruitful analogy\nwith fracture mechanics, we derive the exact energy of the problem and thus\nobtain the equilibrium state for any given choice of physical parameters.",
        "positive": "Isostaticity, auxetic response, surface modes, and conformal invariance\n  in twisted kagome lattices: Model lattices consisting of balls connected by central-force springs provide\nmuch of our understanding of mechanical response and phonon structure of real\nmaterials. Their stability depends critically on their coordination number $z$.\n$d$-dimensional lattices with $z=2d$ are at the threshold of mechanical\nstability and are isostatic. Lattices with $z<2d$ exhibit zero-frequency\n\"floppy\" modes that provide avenues for lattice collapse. The physics of\nsystems as diverse as architectural structures, network glasses, randomly\npacked spheres, and biopolymer networks is strongly influenced by a nearby\nisostatic lattice. We explore elasticity and phonons of a special class of\ntwo-dimensional isostatic lattices constructed by distorting the kagome\nlattice. We show that the phonon structure of these lattices, characterized by\nvanishing bulk moduli and thus negative Poisson ratios and auxetic elasticity,\ndepends sensitively on boundary conditions and on the nature of the kagome\ndistortions. We construct lattices that under free boundary conditions exhibit\nsurface floppy modes only or a combination of both surface and bulk floppy\nmodes; and we show that bulk floppy modes present under free boundary\nconditions are also present under periodic boundary conditions but that surface\nmodes are not. In the the long-wavelength limit, the elastic theory of all\nthese lattices is a conformally invariant field theory with holographic\nproperties, and the surface waves are Rayleigh waves. We discuss our results in\nrelation to recent work on jammed systems. Our results highlight the importance\nof network architecture in determining floppy-mode structure."
    },
    {
        "anchor": "Systematic Field-Theory for the Hard-Core One-Component Plasma: An accurate and systematic equation of state for the hard-core one-component\nplasma (HCOCP) is obtained. The result is based on the Hubbard-Schofield\ntransformation which yields the field-theoretical Hamiltonian, with\ncoefficients expressed in terms of equilibrium correlation functions of the\nreference hard-core fluid. Explicit calculations were performed using the\nGaussian approximation for the effective Hamiltonian and known thermodynamic\nand structural properties of the reference hard-core fluid. For small values of\nthe plasma parameter G and packing fraction the Debye-Huckel result is\nrecovered, while for G>>1, the excess free energy F_ex and internal U_{ex}\nenergy depend linearly on G. The obtained expression for U_ex is in a good\nagreement with the available Monte Carlo data for the HCOCP. We also analyse\nthe validity of the widely used approximation, which represents the free energy\nas a sum of the hard-core and electrostatic part.",
        "positive": "Electric-field frictional effects in confined zwitterionic molecules: We theoretically explore the effect of a transverse electric field on the\nfrictional response of a bi-layer of packed zwitterionic molecules. The\ndipole-moment reorientation promoted by the electric field can lead to either\nstick-slip or smooth sliding dynamics, with average shear stress values varying\nover a wide range. A structure-property relation is revealed by investigating\nthe array of molecules and their mutual orientation and interlocking. Moreover,\nthe thermal friction enhancement previously observed in these molecules is\nshown to be suppressed by the electric field, recovering the expected\nthermolubricity at large-enough fields. The same holds for other basic\ntribological quantities, such as the external load, which can influence\nfriction in opposite ways depending on the strength of the applied electric\nfield. Our findings open a route for the reversible control of friction forces\nvia electric polarization of the sliding surface."
    },
    {
        "anchor": "Post-Tanner spreading of nematic droplets: The quasistationary spreading of a circular liquid drop on a solid substrate\ntypically obeys the so-called Tanner law, with the instantaneous base radius\nR(t) growing with time as R ~ t^{1/10} -- an effect of the dominant role of\ncapillary forces for a small-sized droplet. However, for droplets of nematic\nliquid crystals, a faster spreading law sets in at long times, so that R ~\nt^alpha with alpha significantly larger than the Tanner exponent 1/10. In the\nframework of the thin film model (or lubrication approximation), we describe\nthis \"acceleration\" as a transition to a qualitatively different spreading\nregime driven by a strong substrate-liquid interaction specific to nematics\n(antagonistic anchoring at the interfaces). The numerical solution of the thin\nfilm equation agrees well with the available experimental data for nematics,\neven though the non-Newtonian rheology has yet to be taken into account. Thus\nwe complement the theory of spreading with a post-Tanner stage, noting that the\nspreading process can be expected to cross over from the usual\ncapillarity-dominated stage to a regime where the whole reservoir becomes a\ndiffusive film in the sense of Derjaguin.",
        "positive": "On the rheology of pulmonary surfactant: effects of concentration and\n  consequences for the surfactant replacement therapy: The role of pulmonary surfactant is to reduce the surface tension in the\nlungs and to facilitate breathing. Surfactant replacement therapy (SRT) aims at\nbringing a substitute by instillation into the airways, a technique that has\nproven to be efficient and lifesaving for preterm infants. Adapting this\ntherapy to adults requires to scale the administered dose to the patient body\nweight and to in-crease the lipid concentration, whilst maintaining its surface\nand flow properties similar. Here, we exploit a magnetic wire-based\nmicrorheology technique to measure the viscosity of the exogenous pulmonary\nsurfactant Curosurf in various experimental conditions. The Curosurf viscosity\nis found to increase exponentially with lipid concentration following the\nKrieger-Dougherty law of colloids. The Krieger-Dougherty behavior also predicts\na divergence of the viscosity at the liquid-to-gel transition. For Curosurf the\ntransition concentration is found close to the concentration at which it is\nformulated (117 g L-1 versus 80 g L-1). This outcome suggests that for SRT the\nsurfactant rheological properties need to be monitored and kept within a\ncertain range. The results found here could help in producing suspensions for\nrespiratory distress syndrome adapted to adults. The present work also\ndemonstrates the potential of the magnetic wire microrheology tech-nique as an\naccurate tool to explore biological soft matter dynamics."
    },
    {
        "anchor": "On the specifics of the electrical conductivity anomalies in PVC\n  nanocomposites: A qualitative model describing the \"anomalous\" features of the conductivity\nof polymer nanocomposites, in particular, switching to the conducting state in\nrelatively thick (tens of microns or more) of flexible PVC films is considered.\nIn previously published experimental results, change of conductivity by 10 or\nmore orders of magnitude occurred both in the absence of external influences\n(spontaneously), and under the influence of an applied electric field, as well\nas other initiating factors (such as uniaxial pressure) . In a model of hopping\nconduction mechanism it is shown, that switching in the conduction states under\nthe action of external field significantly (by orders of magnitude) below\nthreshold can be associated with a high-resistance state instability that\nresults from the sequence of \"shorting\" (reversible soft breakdown) of narrow\ninsulating gaps between regions with relatively high conductivity. Increasing\nthe field strength in the remaining insulating gaps ultimately leads to the\nformation of a conducting channel between the external electrodes and switching\nconductivity of the composite film sample in a state of high conductivity. This\ncascade model is essentially based on the transition from the usual description\nof the charge tunneling through single independent insulating gap to take into\naccount correlations between adjacent gaps. In the frame of developed model\nother \"anomalies\" such as exponential dependence of the resistance on the\nsample thickness, pressure, and other influences can be qualitative explained.\nAn analogy of the model with a cascading breakdown of avalanche transistors is\nalso considered.",
        "positive": "A finite excluded volume bond-fluctuation model: Static properties of\n  dense polymer melts revisited: The classical bond-fluctuation model (BFM) is an efficient lattice Monte\nCarlo algorithm for coarse-grained polymer chains where each monomer occupies\nexclusively a certain number of lattice sites. In this paper we propose a\ngeneralization of the BFM where we relax this constraint and allow the overlap\nof monomers subject to a finite energy penalty $\\overlap$. This is done to vary\nsystematically the dimensionless compressibility $g$ of the solution in order\nto investigate the influence of density fluctuations in dense polymer melts on\nvarious s tatic properties at constant overall monomer density. The\ncompressibility is obtained directly from the low-wavevector limit of the\nstatic structure fa ctor. We consider, e.g., the intrachain bond-bond\ncorrelation function, $P(s)$, of two bonds separated by $s$ monomers along the\nchain. It is shown that the excluded volume interactions are never fully\nscreened for very long chains. If distances smaller than the thermal blob size\nare probed ($s \\ll g$) the chains are swollen acc ording to the classical\nFixman expansion where, e.g., $P(s) \\sim g^{-1}s^{-1/2}$. More importantly, the\npolymers behave on larger distances ($s \\gg g$) like swollen chains of\nincompressible blobs with $P(s) \\si m g^0s^{-3/2}$."
    },
    {
        "anchor": "Influence of Side Chain Isomerism on the Rigidity of\n  Poly(3-alkylthiophenes) in Solutions Revealed by Neutron Scattering: Using small angle neutron scattering, we conducted a detailed structural\nstudy of poly(3-alkylthiophenes) dispersed in deuterated dicholorbenzene. The\nfocus was placed on addressing the influence of spatial arrangement of\nconstituent atoms of side chain on backbone conformation. We demonstrate that\nby impeding the {\\pi}- {\\pi} interactions, the branch point in side chain\npromotes torsional motion between backbone units and results in greater chain\nflexibility. Our findings highlight the key role of topological isomerism in\ndetermining the molecular rigidity and are relevant to the current debate about\nthe condition necessary for optimizing the electronic properties of conducting\npolymers via side chain engineering.",
        "positive": "Relaxation dynamics of a linear molecule in a random static medium: A\n  scaling analysis: We present extensive molecular dynamics simulations of the motion of a single\nlinear rigid molecule in a two-dimensional random array of fixed obstacles. The\ndiffusion constant for the center of mass translation, $D_{\\rm CM}$, and for\nrotation, $D_{\\rm R}$, are calculated for a wide range of the molecular length,\n$L$, and the density of obstacles, $\\rho$. The obtained results follow a master\ncurve $D\\rho^{\\mu} \\sim (L^{2}\\rho)^{-\\nu}$ with an exponent $\\mu = -3/4$ and\n1/4 for $D_{\\rm R}$ and $D_{\\rm CM}$ respectively, that can be deduced from\nsimple scaling and kinematic arguments. The non-trivial positive exponent $\\nu$\nshows an abrupt crossover at $L^{2}\\rho = \\zeta_{1}$. For $D_{\\rm CM}$ we find\na second crossover at $L^{2}\\rho = \\zeta_{2}$. The values of $\\zeta_{1}$ and\n$\\zeta_{2}$ correspond to the average minor and major axis of the elliptic\nholes that characterize the random configuration of the obstacles. A violation\nof the Stokes-Einstein-Debye relation is observed for $L^{2}\\rho > \\zeta_{1}$,\nin analogy with the phenomenon of enhanced translational diffusion observed in\nsupercooled liquids close to the glass transition temperature."
    },
    {
        "anchor": "Characteristics and Correlation of Nonaffine Particle Displacements in\n  the Plastic Deformation of Athermal Amorphous Materials: When an amorphous solid is deformed homogeneously, the response exhibits\nheterogeneous plastic instabilities with localized cooperative rearrangement of\ncluster of particles. The heterogeneous behavior plays an important role in\ndeciding the mechanical properties of amorphous solids. In this paper, we\nemploy computer simulation to study the characteristics and the spatial\ncorrelations of these clusters characterized by the non-affine displacements in\namorphous solids under simple shear deformation in the athermal quasistatic\nlimit. The clusters with large displacements are found to be homogeneously\ndistributed in space in the elastic regime, followed by a localization within a\nsystem-spanning shear band after yielding. The distributions of the\ndisplacement field exhibit power-law nature with exponents strongly dependent\non the deformation. The non-affine displacements show strong spatial\ncorrelations which become long-ranged with increasing strain. From our results,\nit is evident that the decay of the correlation functions is exponential in\nnature in the elastic regime. The yielding transition is marked by an abrupt\nchange in the decay after which it is well described by power-law. These\nresults demonstrate a scale-free character of non-affine correlations in the\nstead flow regime. These results are found to be robust and independent of the\nstrain window over which the total non-affine displacement is calculated.",
        "positive": "Surface-to-volume ratio with oscillating gradients: Restrictions to diffusion result in the dispersion of the bulk diffusion\ncoefficient. We derive the exact universal high-frequency behavior of the\ndiffusion coefficient in terms of the surface-to-volume ratio of the\nrestrictions. This frequency dependence can be applied to quantify structure of\ncomplex samples with NMR using oscillating field gradients and static-gradient\nCPMG. We also demonstrate the inter-relations between different equivalent\ndiffusion metrics, and describe how to calculate the effect of restrictions for\narbitrary gradient waveforms."
    },
    {
        "anchor": "Two dimensional vortex structures with multi scale interactions in thin\n  film superconductors: Interaction of particles of many systems can be effectively approximated by\nmultiscale interaction potentials. Such potentials are widely used for\ninvestigation of colloidal systems and colloid-polymer mixtures, complex\nliquids (for instance, water) and other system. Also, it is of particular\ninterest that effective interaction of vortices in a thin superconducting film\ncan be approximated by a multiscale potential. The subject matter of the\npresent paper is a system like this. Based on a multiscale potential we have\nshown that this system demonstrated a large number of different phases. It is\nparticularly important that we analyze the influence of a long-range\ninteraction of the system properties and show that properly taking into account\nlong-range forces results in a dramatic change in the system phase diagram.",
        "positive": "Transport properties in liquids from first principles: the case of\n  liquid water and liquid Argon: Shear and bulk viscosity of liquid water and Argon are evaluated from first\nprinciples in the Density Functional Theory (DFT) framework, by performing\nMolecular Dynamics simulations in the NVE ensemble and using the Kubo-Greenwood\nequilibrium approach. Standard DFT functional is corrected in such a way to\nallow for a reasonable description of van der Waals (vdW) effects. For liquid\nArgon the thermal conductivity has been also calculated. Concerning liquid\nwater, to our knowledge this is the first estimate of the bulk viscosity and of\nthe shear-viscosity/bulk-viscosity ratio from first principles. By analyzing\nour results we can conclude that our first-principles simulations, performed at\na nominal average temperature of 366 K to guarantee that the systems is\nliquid-like, actually describe the basic dynamical properties of liquid water\nat about 330 K. In comparison with liquid water, the normal, monatomic liquid\nAr is characterized by a much smaller bulk-viscosity/shear-viscosity ratio\n(close to unity) and this feature is well reproduced by our first-principles\napproach which predicts a value of the ratio in better agreement with\nexperimental reference data than that obtained using the empirical\nLennard-Jones potential. The computed thermal conductivity of liquid Argon is\nalso in good agreement with the experimental value."
    },
    {
        "anchor": "Equilibrium properties of the lattice fluid with the repulsion between\n  the nearest neighbors on the two-level lattice with nonrectangular geometry: The equilibrium properties of the lattice fluid with the repulsion between\nthe nearest neighbors on the two-level planar triangular lattice are\ninvestigated. The numerical results obtained from the analytical expressions\nare compared with the Monte Carlo simulation data. It is shown that the\npreviously proposed diagrammatic approximation makes it possible to determine\nthe equilibrium characteristics of the lattice fluid with the repulsion between\nthe nearest neighbors on a two-level lattice with an accuracy comparable to the\naccuracy of modelling the system using the Monte Carlo method in the entire\nrange of thermodynamic parameters. It was found that, in contrast to a similar\none-level system, a lattice fluid with the repulsion between the nearest\nneighbors undergoes a first-order phase transition.",
        "positive": "Fluctuating Nematic Elastomer Membranes: a New Universality Class: We study the flat phase of nematic elastomer membranes with rotational\nsymmetry spontaneously broken by in-plane nematic order. Such state is\ncharacterized by a vanishing elastic modulus for simple shear and soft\ntransverse phonons. At harmonic level, in-plane orientational (nematic) order\nis stable to thermal fluctuations, that lead to short-range in-plane\ntranslational (phonon) correlations. To treat thermal fluctuations and relevant\nelastic nonlinearities, we introduce two generalizations of two-dimensional\nmembranes in a three dimensional space to arbitrary D-dimensional membranes\nembedded in a d-dimensional space, and analyze their anomalous elasticities in\nan expansion about D=4. We find a new stable fixed point, that controls\nlong-scale properties of nematic elastomer membranes. It is characterized by\nsingular in-plane elastic moduli that vanish as a power-law eta_lambda=4-D of a\nrelevant inverse length scale (e.g., wavevector) and a finite bending rigidity.\nOur predictions are asymptotically exact near 4 dimensions."
    },
    {
        "anchor": "Study of Interfacial Rheology of Human Serum Albumin Microcapsules using\n  Electrodeformation Technique: In the present work, we conducted mechanical characterization of the membrane\nof human serum albumin (HSA) microcapsules using the electrodeformation\ntechnique which shows that HSA capsules are strain-softening in nature. The\nviscoelasto-electrohydrodynamic model was utilized to understand the creep\nmechanism in the HSA capsules. The effect of different reaction parameters such\nas protein concentration and pH on the morphology of the capsule membrane was\ninvestigated, and an attempt has been made to correlate microstructure with the\nmechanical properties. The pH has a remarkable effect on the morphology of HSA\nmicrocapsules which is also reflected in their mechanical characteristics. The\ncapsule synthesized with carbonate buffer shows very distinct morphology with\npores on the membrane surface, making the membrane less elastic with\nsignificant nonrecoverable creep. The capsules synthesized with different\nprotein concentrations at the same pH condition show different morphology and\nthus different rheological properties. Capsules with a low concentration of HSA\nshow smooth membrane structure with higher Young's modulus than the capsules\nsynthesized at a very high concentration which show a rough folded wavy\nstructure with low membrane elastic modulus. The effect of frequency on the\ninterfacial rheological properties of human serum albumin capsules was studied\nusing a frequency sweep test using the electrodeformation technique. The\nrheological properties were computed incorporating the\nviscoelasto-electrohydrodynamic model for the oscillatory response of capsules.\nThe results show that the elastic response dominates in the high-frequency\nregime. Thus the electrodeformation technique allows studying the effect of\nvery high-frequency 1 Hz to 1 kHz, which is otherwise not possible with the\nconventional rheometers.",
        "positive": "Rack-and-pinion effects in molecular rolling friction: Rolling lubrication with spherical molecules working as 'nanobearings' has\nfailed experimentally so far, without a full understanding of the physics\ninvolved and of the reasons why. Past model simulations and common sense have\nshown that molecules can only roll when they are not too closely packed to jam.\nThe same type of model simulations now shows in addition that molecular rolling\nfriction can develop deep minima once the molecule's peripheral 'pitch' can\nmatch the substrate periodicity, much as ordinary cogwheels do in a\nrack-and-pinion system. When the pinion-rack matching is bad, the driven\nmolecular rolling becomes discontinuous and noisy, whence energy is dissipated\nand friction is large. This suggests experiments to be conducted by varying the\nrack-and-pinion matching. That could be pursued not only by changing molecules\nand substrates, but also by applying different sliding directions within the\nsame system, or by applying pressure, to change the effective matching."
    },
    {
        "anchor": "Scanning acoustic microscopy for mapping the microstructure of soft\n  materials: Acoustics provides a powerful modality with which to 'see' the mechanical\nproperties of a wide range of elastic materials. It is particularly adept at\nprobing soft materials where excellent contrast and propagation distance can be\nachieved. We have constructed a scanning acoustic microscope capable of mapping\nthe microstructure of such materials. We review the general principles of\nscanning acoustic microscopy and present new examples of its application in\nimaging biological matter, industrial materials and particulate systems.",
        "positive": "Active microrheology of colloidal suspensions of hard cuboids: By performing dynamic Monte Carlo simulations, we investigate the\nmicrorheology of isotropic suspensions of hard-core colloidal cuboids. In\nparticular, we infer the local viscoelastic behaviour of these fluids by\nstudying the dynamics of a probe spherical particle that is incorporated in the\nhost phase and is dragged by an external force. This technique, known as active\nmicrorheology, allows one to characterise the microscopic response of soft\nmaterials upon application of a constant force, whose intensity spans here\nthree orders of magnitude. By tuning the geometry of cuboids from oblate to\nprolate as well as the system density, we observe different responses that are\nquantified by measuring the effective friction perceived by the probe particle.\nThe resulting friction coefficient exhibits a linear regime at forces that are\nmuch weaker and larger than the thermal forces, whereas a non-linear,\nforce-thinning regime is observed at intermediate force intensities."
    },
    {
        "anchor": "Strategies for deliveries of anti-cancer drugs from perspectives of a\n  measurement theory and an adsorption theory: In this letter, we present anti-cancer drug delivery strategies using\nknowledges obtained from our recent studies. We have conducted inverse analyses\nof \"density distributions of colloidal particles near a focused surface\" and\n\"pair potentials between the surface and the colloidal particle\" using data\nmeasured by optical tweezers (OT) and atomic force microscopy (AFM).\nNon-additive Asakura-Oosawa (NAO) theory and a lattice theory in statistical\nmechanics of simple polymers have been also our research topics. Summarizing\nthe knowledges, we propose two strategies to increase the delivery rate of\ncapsule shaped anti-cancer drugs to cancer cells. We consider that enhanced\nrepulsion between the normal cell and the drug accelerates the attraction\nbetween the cancer cell and the drug, which can be named enhanced repulsion and\naccelerated adsorption (ERAA) effect. To realize the ERAA effect, we propose a\nsupporting method for measuring the interactions using OT and AFM. In the\nsecond strategy, dose of water-soluble polymers is considered to realize\nadsorptions of the drugs and cancer cell derived exosomes onto the cancer\ncells, which we call non-specific and selective adsorption (NSSA) effect. In\nthe main text, we explain the NSSA effect using the NAO theory. Moreover, we\nexplain that structural stabilities of normal dispersed proteins around the\ncancer cells are not largely destroyed by the dosed polymers from the viewpoint\nof the lattice theory.",
        "positive": "Entropy driven thermo-gelling vitrimer: Thermo-gelling polymers have been envisioned as promising smart biomaterials\nbut limited to their weak mechanical and thermodynamic stabilities. Here we\npropose a new thermo-gelling vitrimer, which remains at a liquid state because\nof the addition of protector molecules preventing the crosslinking, and with\nincreasing temperature, an entropy driven crosslinking occurs to induce the\nsol-gel transition. Moreover, we find that the activation barrier in the\nmetathesis reaction of vitrimers plays an important role, and experimentally\none can use catalysts to tune the activation barrier to drive the vitrimer to\nform an equilibrium gel at high temperature, which is not subject to any\nthermodynamic instability. We formulate a mean field theory to describe the\nentropy driven crosslinking of the vitrimer, which agrees quantitatively with\ncomputer simulations, and paves the way for design and fabrication of novel\nvitrimers for biomedical applications."
    },
    {
        "anchor": "The conformational phase diagram of neutral polymers in the presence of\n  attractive crowders: Extensive coarse grained molecular dynamics simulations are performed to\ninvestigate the conformational phase diagram of a neutral polymer in the\npresence of attractive crowders. We show that, for low crowded densities, the\npolymer predominantly shows three phases as a function of both intra polymer\nand polymer-crowder interactions: (1) weak intra polymer and weak\npolymer-crowder attractive interactions induce extended or coil polymer\nconformations (phase E) (2) strong intra polymer and relatively weak\npolymer-crowder attractive interactions induce collapsed or globular\nconformations (phase CI) and (3) strong polymer-crowder attractive\ninteractions, regardless of intra polymer interactions, induce a second\ncollapsed or globular conformation that encloses bridging crowders (phase CB).\nThe detailed phase diagram is obtained by determining the phase boundaries\ndelineating the different phases based on an analysis of the radius of gyration\nas well as bridging crowders. The dependence of the phase diagram on strength\nof crowder-crowder attractive interactions and crowder density is clarified. We\nalso show that when the crowder density is increased, a third collapsed phase\nof the polymer emerges for weak intra polymer attractive interactions. This\ncrowder density induced compaction is shown to be enhanced by stronger\ncrowder-crowder attraction and is different from the depletion induced collapse\nmechanism which is primarily driven by repulsive interactions. We also provide\na unified explanation of the observed reentrant swollen/extended conformations\nof earlier simulations of weak and strongly self interacting polymers in terms\nof crowder-crowder attractive interactions.",
        "positive": "Role of quantum fluctuations in structural dynamics of liquids of light\n  molecules: A possible role of quantum effects, such as tunneling and zero-point energy,\nin the structural dynamics of supercooled liquids is studied by dielectric\nspectroscopy. Presented results demonstrate that the liquids, bulk\n3-methylpentane 3MP and confined normal and deuterated water have low glass\ntransition temperature and unusually low for their class of materials steepness\nof the temperature dependence of structural relaxation, or fragility. Although\nwe do not find any signs of tunneling in structural relaxation of these\nliquids, their unusually low fragility can be well described by the influence\nof the quantum fluctuations. Confined water presents especially interesting\ncase in comparison to the earlier data on bulk low-density amorphous and vapor\ndeposited water. Confined water exhibits much weaker isotope effect than bulk\nwater, although the effect is still significant. We show that it can be\nascribed to the change of the energy barrier for relaxation due to a decrease\nin the zero-point energy upon D-H substitution. The observed difference in the\nbehavior of confined and bulk water demonstrates high sensitivity of quantum\neffects to the barrier heights and structure of water. Moreover, these results\ndemonstrate that extrapolation of confined water properties to the bulk water\nbehavior is questionable."
    },
    {
        "anchor": "A new tuning fork-based instrument for oscillatory shear rheology of\n  nano-confined liquids: We present a new method to measure rheological response of liquids confined\nto nano-scale which exhibit a considerable slow-down in dynamics compared to\nbulk liquids. The method relies on using a robust force sensor that has a\nsensitivity to measure shear forces in the range of 1 to 10 nN and a stiffness\nof 55000 N/m to avoid thermal noise. Off-resonance operation ensures\napplication of a range of shear frequencies . This range is higher than the\ninverse of the system's mechanical relaxation time and allows the measurement\nof non-linear effects emerging due to significant \"slow down\" in dynamics upon\nconfinement. The instrument is a step forward towards resolving the\ncontroversies about the nature of nano-confined liquids.",
        "positive": "Shock waves in capillary collapse of colloids: a model system for\n  two--dimensional screened Newtonian gravity: Using Brownian dynamics simulations, density functional theory, and\nanalytical perturbation theory we study the collapse of a patch of\ninterfacially trapped, micrometer-sized colloidal particles, driven by\nlong-ranged capillary attraction. This attraction {is formally analogous} to\ntwo--dimensional (2D) screened Newtonian gravity with the capillary length\n\\hat{\\lambda} as the screening length. Whereas the limit \\hat{\\lambda} \\to\n\\infty corresponds to the global collapse of a self--gravitating fluid, for\nfinite \\hat{\\lambda} we predict theoretically and observe in simulations a\nringlike density peak at the outer rim of a disclike patch, moving as an\ninbound shock wave. Possible experimental realizations are discussed."
    },
    {
        "anchor": "A multiscale biophysical model gives quantized metachronal waves in a\n  lattice of cilia: Motile cilia are slender, hair-like cellular appendages that spontaneously\noscillate under the action of internal molecular motors and are typically found\nin dense arrays. These active filaments coordinate their beating to generate\nmetachronal waves that drive long-range fluid transport and locomotion. Until\nnow, our understanding of their collective behavior largely comes from the\nstudy of minimal models that coarse-grain the relevant biophysics and the\nhydrodynamics of slender structures. Here we build on a detailed biophysical\nmodel to elucidate the emergence of metachronal waves on millimeter scales from\nnanometer scale motor activity inside individual cilia. Our study of a 1D\nlattice of cilia in the presence of hydrodynamic and steric interactions\nreveals how metachronal waves are formed and maintained. We find that in\nhomogeneous beds of cilia these interactions lead to multiple attracting\nstates, all of which are characterized by an integer charge that is conserved.\nThis even allows us to design initial conditions that lead to predictable\nemergent states. Finally, and very importantly, we show that in nonuniform\nciliary tissues, boundaries and inhomogeneities provide a robust route to\nmetachronal waves.",
        "positive": "Gap maps and intrinsic diffraction losses in one-dimensional photonic\n  crystal slabs: A theoretical study of photonic bands for one-dimensional (1D) lattices\nembedded in planar waveguides with strong refractive index contrast is\npresented. The approach relies on expanding the electromagnetic field on the\nbasis of guided modes of an effective waveguide, and on treating the coupling\nto radiative modes by perturbation theory. Photonic mode dispersion, gap maps,\nand intrinsic diffraction losses of quasi-guided modes are calculated for the\ncase of self-standing membranes as well as for Silicon-on-Insulator structures.\nPhotonic band gaps in a waveguide are found to depend strongly on the core\nthickness and on polarization, so that the gaps for transverse electric and\ntransverse magnetic modes most often do not overlap. Radiative losses of\nquasi-guided modes above the light line depend in a nontrivial way on structure\nparameters, mode index and wavevector. The results of this study may be useful\nfor the design of integrated 1D photonic structures with low radiative losses."
    },
    {
        "anchor": "Local Stress Relaxation and Shear-banding in a Dry Foam under Shear: We have developed a realistic simulation of 2D dry foams under quasi-static\nshear. After a short transient, a shear-banding instability is observed. These\nresults are compared with measurements obtained on real 2D (confined) foams.\nThe numerical model allows us to exhibit the mechanical response of the\nmaterial to a single plastication event. From the analysis of this elastic\npropagator, we propose a scenario for the onset and stability of the flow\nlocalization process in foams, which should remain valid for most athermal\namorphous systems under creep flow.",
        "positive": "Cooling a spherical nematic shell: Within the framework of Landau-de Gennes theory for nematic liquid crystals,\nwe study the temperature-induced isotropic-nematic phase transition on a\nspherical shell. Below a critical temperature, a thin layer of nematic coating\na microscopic spherical particle exhibits non-uniform textures due to the\ngeometrical frustration. We find the exact value of critical threshold for the\ntemperature and determine exactly the nematic textures at the transition by\nmeans of a weakly nonlinear analysis. The critical temperature is affected by\nthe extrinsic curvature of the sphere, and the nematic alignment is consistent\nwith the Poincar\\'e-Hopf index theorem and experimental observations. The\nstability analysis of the bifurcate textures at the isotropic-nematic\ntransition highlight that only the tetrahedral configuration is stable."
    },
    {
        "anchor": "Distribution of forces and 'hydrodynamic clustering' in a shear\n  thickened colloid: Sheared concentrated colloids with short range polymer coats are examined via\nsimulations. Distributions of force are found to be sums of exponentials. The\n'hydrodynamic clustering' underlying the shear thickening effect is shown, in\nthis system, to be a network of percolating coat contacts, with coats both in\ncompression and extension. The geometry and kinetics of this network are\nexplored along with its relation to the bulk stress tensor. Particles\nexperience strong fluctuations in force over epochs $\\it{circa}$ 10% strain.\nDensity fluctuations up to glassy volume fractions give rise to scattering\npeaks at low Q in the thickening regime. There is some commonality in the\nphysics of this colloid particulate system and other granular media.",
        "positive": "The bending energy of a semi-flexible polymer chain and the polygons of\n  the polymer chain: We consider random walk model of a semi-flexible polymer chain on a square\nand a cubic lattice to enumerate conformations of the polymer chain in two and\nthree dimensions, respectively. The bending energy of the chain is assumed as\nthe key factor which controls the minimum average length of the chain in\nbetween two successive bends in the chain; and the average length of the chains\nper unit bend is defined as the persistence length of the polymer chain. It has\nbeen found that the minimum energy required to bend the chain is expressed in\nthe form of simple relation which includes space dimensionality, step fugacity\nand persistence length."
    },
    {
        "anchor": "Correlation between crystalline order and vitrification in colloidal\n  monolayers: We investigate experimentally the relationship between local structure and\ndynamical arrest in a quasi-2d colloidal model system which approximates hard\ndiscs. We introduce polydispersity to the system to suppress crystallisation.\nUpon compression, the increase in structural relaxation time is accompanied by\nthe emergence of local hexagonal symmetry. Examining the dynamical\nheterogeneity of the system, we identify three types of motion :\n\"zero-dimensional\" corresponding to beta-relaxation, \"one-dimensional\" or\nstringlike motion and \"two-dimensional\" motion. The dynamic heterogeneity is\ncorrelated with the local order, that is to say locally hexagonal regions are\nmore likely to be dynamically slow. However we find that lengthscales\ncorresponding to dynamic heterogeneity and local structure do not appear to\nscale together approaching the glass transition.",
        "positive": "Universal Robotic Gripper based on the Jamming of Granular Material: Gripping and holding of objects are key tasks for robotic manipulators. The\ndevelopment of universal grippers able to pick up unfamiliar objects of widely\nvarying shape and surface properties remains, however, challenging. Most\ncurrent designs are based on the multi-fingered hand, but this approach\nintroduces hardware and software complexities. These include large numbers of\ncontrollable joints, the need for force sensing if objects are to be handled\nsecurely without crushing them, and the computational overhead to decide how\nmuch stress each finger should apply and where. Here we demonstrate a\ncompletely different approach to a universal gripper. Individual fingers are\nreplaced by a single mass of granular material that, when pressed onto a target\nobject, flows around it and conforms to its shape. Upon application of a vacuum\nthe granular material contracts and hardens quickly to pinch and hold the\nobject without requiring sensory feedback. We find that volume changes of less\nthan 0.5% suffice to grip objects reliably and hold them with forces exceeding\nmany times their weight. We show that the operating principle is the ability of\ngranular materials to transition between an unjammed, deformable state and a\njammed state with solid-like rigidity. We delineate three separate mechanisms,\nfriction, suction and interlocking, that contribute to the gripping force.\nUsing a simple model we relate each of them to the mechanical strength of the\njammed state. This opens up new possibilities for the design of simple, yet\nhighly adaptive systems that excel at fast gripping of complex objects."
    },
    {
        "anchor": "Running streams of a ferroelectric nematic liquid crystal on a lithium\n  niobate surface: Sessile droplets of a ferroelectric nematic liquid crystalline material were\nexposed to surface electric fields produced by pyroelectric and photogalvanic\n(photovoltaic) effects in X-cut iron-doped lithium niobate crystals. The\nresulting dynamic processes were monitored by polarization optical\n(video)microscopy (POM). During heating/cooling cycles, at first, the droplets\nchange their shape from spherical to extended ellipsoidal. Then they start to\nmove rapidly along the surface electric field, i.e., along the crystal's polar\naxis (c-axis). During this motion, several droplets merge into running streams\n(tendrils) extending towards the edges of the top surface area. Finally,\npractically all liquid crystalline material is transported from the top surface\nto the side surfaces of the crystal. At stabilized temperature, laser\nillumination of the assembly causes dynamic processes that are localized to the\nilluminated area. Also, in this case, the LC droplets merge into several\ntendril-like formations that are preferentially oriented along the c-axis of\nthe crystal. The pattern of tendrils fluctuates with time, but it persists as\nlong as the illumination is present. In this case, the LC material is\ntransported between the central and the edge region of the illuminated area.",
        "positive": "Using deformable particles for single particle measurements of velocity\n  gradient tensors: We measure the deformation of particles made of several slender arms in a\ntwo-dimensional (2D) linear shear and a three-dimensional (3D) turbulent flow.\nWe show how these measurements of arm deformations along with the rotation rate\nof the particle allow us to extract the velocity gradient tensor of the flow.\nThe particles used in the experiments have three symmetric arms in a plane\n(triads) and are fabricated using 3D printing of a flexible polymeric material.\nDeformation measurements of a particle free to rotate about a fixed axis in a\n2D simple shear flow are used to validate our model relating particle\ndeformations to the fluid strain. We then examine deformable particles in a 3D\nturbulent flow created by a jet array in a vertical water tunnel. Particle\norientations and deformations are measured with high precision using four high\nspeed cameras and have an uncertainty on the order of $10^{-4}$ radians.\nMeasured deformations in 3D turbulence are small and only slightly larger than\nour orientation measurement uncertainty. Simulation results for triads in\nturbulence show deformations similar to the experimental observations.\nDeformable particles offer a promising method for measuring the full local\nvelocity gradient tensor from measurements of a single particle where\ntraditionally a high concentration of tracer particles would be required."
    },
    {
        "anchor": "Effect of non-specific interactions on formation and stability of\n  specific complexes: We introduce a simple model to describe the interplay between specific and\nnon-specific interactions. We study the influence of various physical factors\non the static and dynamic properties of the specific interactions of our model\nand show that contrary to intuitive expectations, non-specific interactions can\nassist in the formation of specific complexes and increase their stability. We\nthen discuss the relevance of these results for biological systems.",
        "positive": "Electrostatic interaction between dissimilar colloids at fluid\n  interfaces: The electrostatic interaction between two non-identical, moderately charged\ncolloids situated in close proximity of each other at a fluid interface is\nstudied. By resorting to a well-justified model system, this problem is\nanalytically solved within the framework of linearized Poisson-Boltzmann (PB)\ndensity functional theory (DFT). The resulting interaction comprises a surface\nand a line part, both of which, as functions of the inter-particle separation,\nshow a rich behavior including monotonic as well as non-monotonic variations.\nIn almost all cases, these variations cannot be captured correctly by using the\nsuperposition approximation. Moreover, expressions for the surface tensions,\nthe line tensions and the fluid-fluid interfacial tension, which are all\nindependent of the inter-particle separation, are obtained. Our results are\nexpected to be particularly useful for emulsions stabilized by oppositely\ncharged particles."
    },
    {
        "anchor": "General phase diagram for antiferroelectric liquid crystals in\n  dependence on enantiomeric excess: The phase diagram of the prototype antiferroelectric liquid crystal MHPOBC in\ndependence of enantiomeric excess was measured. It was shown that the SmCbeta\nphase in very pure samples is the SmCFI2 phase with a four layer structure, and\nonly after small racemization it transforms into the ferroelectric SmC phase.\nThe phase diagram was theoretically explained by taking into account longer\nrange bilinear and short range biquadratic interlayer interactions, that lead\nto the distorted clock structures and first order transitions between them.",
        "positive": "Synthetic Chemotaxis and Collective Behavior in Active Matter: Conspectus: The ability to navigate in chemical gradients, called chemotaxis,\nis crucial for the survival of microorganisms. It allows them to find food and\nto escape from toxins. Many microorganisms can produce the chemicals to which\nthey respond themselves and use chemotaxis for signalling which can be seen as\na basic form of communication. Remarkably, the past decade has let to the\ndevelopment of synthetic microswimmers like e.g. autophoretic Janus colloids,\nwhich can self-propel through a solvent, analogously to bacteria and other\nmicroorganims. The mechanism underlying their self-propulsion involves the\nproduction of certain chemicals. The same chemicals involved in the\nself-propulsion mechanism also act on other microswimmers and bias their\nswimming direction towards (or away from) the producing microswimmer. Synthetic\nmicroswimmers therefore provide a synthetic analogue to chemotactic motile\nmicroorganisms. When these interactions are attractive, they commonly lead to\nclusters, even at low particle density. These clusters may either proceed\ntowards macrophase separation, resembling Dictyostelium aggregation, or, as\nshown very recently, lead to dynamic clusters of self-limited size (dynamic\nclustering) as seen in experiments in autophoretic Janus colloids. Besides the\nclassical case where chemical interactions are attractive, this Account\ndiscusses, as its main focus, repulsive chemical interactions, which can create\na new and less known avenue to pattern formation in active systems leading to a\nvariety of pattern, including clusters which are surrounded by shells of\nchemicals, travelling waves and more complex continously reshaping patterns. In\nall these cases `synthetic signalling' can crucially determine the collective\nbehavior of synthetic microswimmer ensembles and can be used as a design\nprinciple to create patterns in motile active particles."
    },
    {
        "anchor": "Constant rate shearing on two dimensional cohesive disks: We performed two-dimensional Molecular Dynamics simulations of cohesive disks\nunder shear. The cohesion between the disks is added by the action of springs\nbetween very next neighbouring disks, modelling capillary forces. The geometry\nof the cell allows disk-disk shearing and not disk-cell wall shearing as it is\ncommonly found in literature. Does a stick-slip phenomenon happen though the\nupper cover moves at a constant velocity, i.e. with an infinite shearing force?\nWe measured the forces acted by the disks on the upper cover for different\nshearing rates, as well as the disk velocities as a function of the distance to\nthe bottom of the cell. It appears that the forces measured versus time present\na periodic behavior,very close to a stick slip phenomenon, for shearing rates\nlarger than a given threshold. The disks' collective displacements in the\nshearing cell (back and ahead) is the counterpart of the constant velocity of\nthe upper cover leading to a periodic behavior of the shear stress.",
        "positive": "Enhanced microscopic dynamics in mucus gels under a mechanical load in\n  the linear viscoelastic regime: Mucus is a biological gel covering the surface of several tissues and\ninsuring key biological functions, including as a protective barrier against\ndehydration, pathogens penetration, or gastric acids. Mucus biological\nfunctioning requires a finely tuned balance between solid-like and fluid-like\nmechanical response, insured by reversible bonds between mucins, the\nglycoproteins that form the gel. In living organisms, mucus is subject to\nvarious kinds of mechanical stresses, e.g. due to osmosis, bacterial\npenetration, coughing and gastric peristalsis. However, our knowledge of the\neffects of stress on mucus is still rudimentary and mostly limited to\nmacroscopic rheological measurements, with no insight into the relevant\nmicroscopic mechanisms. Here, we run mechanical tests simultaneously to\nmeasurements of the microscopic dynamics of pig gastric mucus. Strikingly, we\nfind that a modest shear stress, within the macroscopic rheological linear\nregime, dramatically enhances mucus reorganization at the microscopic level, as\nsignalled by a transient acceleration of the microscopic dynamics, by up to two\norders of magnitude. We rationalize these findings by proposing a simple yet\ngeneral model for the dynamics of physical gels under strain and validate its\nassumptions through numerical simulations of spring networks. These results\nshed new light on the rearrangement dynamics of mucus at the microscopic scale,\nwith potential implications in phenomena ranging from mucus clearance to\nbacterial and drug penetration."
    },
    {
        "anchor": "Density scaling of the diffusion coefficient at various pressures in\n  viscous liquids: Fundamental thermodynamics and an earlier elastic solid-state point defect\nmodel [P. Varotsos and K. Alexopoulos, Phys. Rev B 15, 4111 (1977); 18, 2683\n(1978)] are employed to formulate an analytical second-order polynomial\nfunction describing the density scaling of the diffusion coefficient in viscous\nliquids. The function parameters are merely determined by the scaling exponent,\nwhich is directly connected with the Gruneisen constant. Density scaling\ndiffusion coefficient isotherms obtained at different pressures collapse on a\nunique master curve, in agreement with recent computer simulation results of\nLennard-Jones viscous liquids, [D. Coslovich and C.M. Roland, J. Phys. Chem. B\n112, 1329 (2008)].",
        "positive": "From predicting to learning dissipation from pair correlations of active\n  liquids: Active systems, which are driven out of equilibrium by local non-conservative\nforces, can adopt unique behaviors and configurations. An important challenge\nin the design of novel materials which utilize such properties is to precisely\nconnect the static structure of active systems to the dissipation of energy\ninduced by the local driving. Here, we use tools from liquid-state theories and\nmachine learning to take on this challenge. We first demonstrate analytically\nfor an isotropic active matter system that dissipation and pair correlations\nare closely related when driving forces behave like an active temperature. We\nthen extend a nonequilibrium mean-field framework for predicting these pair\ncorrelations, which unlike most existing approaches is applicable even for\nstrongly interacting particles and far from equilibrium, to predicting\ndissipation in these systems. Based on this theory, we reveal a robust analytic\nrelation between dissipation and structure which holds even as the system\napproaches a nonequilibrium phase transition. Finally, we construct a neural\nnetwork which maps static configurations of particles to their dissipation rate\nwithout any prior knowledge of the underlying dynamics. Our results open novel\nperspectives on the interplay between dissipation and organization\nout-of-equilibrium."
    },
    {
        "anchor": "Structure of molecular liquids: cavity and bridge functions of the hard\n  spheroid fluid: We present methodologies for calculating the direct correlation function,\nc(1,2), the cavity function, y(1,2), and the bridge function, b(1,2), for\nmolecular liquids, from Monte Carlo simulations. As an example we present\nresults for the isotropic hard spheroid fluid with elongation e=3. The\nsimulation data are compared with the results from integral equation theory. In\nparticular, we solve the Percus-Yevick and Hypernetted Chain equations. In\naddition, we calculate the first two terms in the virial expansion of the\nbridge function and incorporate this into the closure. At low densities, the\nbridge functions calculated by theory and from simulation are in good\nagreement, lending support to the correctness of our numerical procedures. At\nhigher densities, the hypernetted chain results are brought into closer\nagreement with simulation by incorporating the approximate bridge function, but\nsignificant discrepancies remain.",
        "positive": "Solid-amorphous transition is related to the waterlike anomalies in a\n  fluid without liquid-liquid phase transition: The most accepted origin for the water anomalous behavior is the phase\ntransition between two liquids (LLPT) in the supercooled regime connected to\nthe glassy first order phase transition at lower temperatures. Two length\nscales potentials are an effective approach that have long being employed to\nunderstand the properties of fluids with waterlike anomalies and, more\nrecently, the behavior of colloids and nanoparticles. These potentials can be\nparameterized to have distinct shapes, as a pure repulsive ramp, such as the\nmodel proposed by de Oliveira et al. [J. Chem. Phys. 124, 64901 (2006)]. This\nmodel has waterlike anomalies despite the absence of LLPT. To unravel how the\nwaterlike anomalies are connected to the solid phases we employ Molecular\nDynamics simulations. We have analyzed the fluid-solid transition under\ncooling, with two solid crystalline phases, BCC and HCP, and two amorphous\nregions being observed. We show how the competition between the scales creates\nan amorphous cluster in the BCC crystal that leads to the amorphization at low\ntemperatures. A similar mechanism is found in the fluid phase, with the system\nchanging from a BCC-like to an amorphous-like structure in the point where a\nmaxima in $k_T$ is observed. With this, we can relate the competition between\ntwo fluid structures with the amorphous clusterization in the BCC phase.Those\nfindings help to understand the origins of waterlike behavior in systems\nwithout liquid-liquid critical point."
    },
    {
        "anchor": "Local Density Fluctuation Governs the Divergence of Viscosity underlying\n  Elastic and Hydrodynamic Anomalies in a 2D Glass-Forming Liquid: If a liquid is cooled rapidly to form a glass, its structural relaxation\nbecomes retarded, producing a drastic increase in viscosity. In two dimensions,\nstrong long-wavelength fluctuations persist, even at low temperature, making it\ndifficult to evaluate the microscopic structural relaxation time. This Letter\nshows that, in a 2D glass-forming liquid, relative displacement between\nneighbor particles yields a relaxation time that grows in proportion to the\nviscosity. In addition to thermal elastic vibrations, hydrodynamic fluctuations\nare found to affect the long-wavelength dynamics, yielding a logarithmically\ndiverging diffusivity in the long-time limit.",
        "positive": "Frequency-Rank Correlations of Rhodopsin Mutations with Tuned\n  Hydropathic Roughness Based on Self-Organized Criticality: The behavior of disease-linked mutations of membrane proteins is especially\nsimple in rhodopsin, where they are well-studied, as they are responsible for\nretinitis pigmentosa, RP (retinal degeneration). Here we show that the\nfrequency of occurrence of single RP mutations is strongly influenced by their\nposttranslational survival rates, and that this survival correlates well (82%)\nwith a long-range, non-local hydropathic measure of the roughness of the water\ninterfaces of ex-membrane rhodopsin based on self-organized criticality (SOC).\nIt is speculated that this concept may be generally useful in studying survival\nrates of many mutated proteins."
    },
    {
        "anchor": "Ferroelectric nematic liquids with conics: Spontaneous electric polarization of solid ferroelectrics follows aligning\ndirections of crystallographic axes. Domains of differently oriented\npolarization are separated by domain walls (DWs), which are predominantly flat\nand run along directions dictated by the bulk translational order and the\nsample surfaces. Here we explore DWs in a ferroelectric nematic (NF) liquid\ncrystal, which is a fluid with polar long-range orientational order but no\ncrystallographic axes nor facets. We demonstrate that DWs in the absence of\nbulk and surface aligning axes are shaped as conic sections. The conics bisect\nthe angle between two neighboring polarization fields to avoid electric\ncharges. The remarkable bisecting properties of conic sections, known for\nmillennia, play a central role as intrinsic features of liquid ferroelectrics.\nThe findings could be helpful in designing patterns of electric polarization\nand space charge.",
        "positive": "Stability of supercooled binary liquid mixtures: Recently the supercooled Wahnstrom binary Lennard-Jones mixture was partially\ncrystallized into ${\\rm MgZn_2}$ phase crystals in lengthy Molecular Dynamics\nsimulations. We present Molecular Dynamics simulations of a modified\nKob-Andersen binary Lennard-Jones mixture that also crystallizes in lengthy\nsimulations, here however by forming pure fcc crystals of the majority\ncomponent. The two findings motivate this paper that gives a general\nthermodynamic and kinetic treatment of the stability of supercooled binary\nmixtures, emphasizing the importance of negative mixing enthalpy whenever\npresent. The theory is used to estimate the crystallization time in a\nKob-Andersen mixture from the crystallization time in a series of relared\nsystems. At T=0.40 we estimate this time to be 5$\\times 10^{7}$ time units\n($\\approx 1. ms$). A new binary Lennard-Jones mixture is proposed that is not\nprone to crystallization and faster to simulate than the two standard binary\nLennard-Jones mixtures; this is obtained by removing the like-particle\nattractions by switching to Weeks-Chandler-Andersen type potentials, while\nmaintaining the unlike-particle attraction."
    },
    {
        "anchor": "Data-driven identification and analysis of the glass transition in\n  polymer melts: Understanding the nature of glass transition, as well as precise estimation\nof the glass transition temperature for polymeric materials, remain open\nquestions in both experimental and theoretical polymer sciences. We propose a\ndata-driven approach, which utilizes the high-resolution details accessible\nthrough the molecular dynamics simulation and considers the structural\ninformation of individual chains. It clearly identifies the glass transition\ntemperature of polymer melts of weakly semiflexible chains. By combining\nprincipal component analysis and clustering, we identify the glass transition\ntemperature in the asymptotic limit even from relatively short-time\ntrajectories, which just reach into the Rouse-like monomer displacement regime.\nWe demonstrate that fluctuations captured by the principal component analysis\nreflect the change in a chain's behaviour: from conformational rearrangement\nabove to small rearrangements below the glass transition temperature. Our\napproach is straightforward to apply, and should be applicable to other\npolymeric glass-forming liquids.",
        "positive": "Dynamics of a collection of active particles on a two-dimensional\n  periodic undulated surface: We study the dynamics of circular active particles (AP) on a two dimensional\nperiodic undulated surface. Each particle has an internal energy mechanism\nwhich is modeled by an active friction force and it is controlled by an\nactivity parameter $v_0$. It acts as negative friction if the speed of the\nparticle is smaller than $v_0$ and normal friction otherwise. Surface\nundulation is modeled by the periodic undulation of fixed amplitude and\nwavelength and is measured in terms of a dimensionless ratio of amplitude and\nwavelength, $\\bar{h}$. The dynamics of the particle is studied for different\nactivities, $v_0$ and surface undulations (SU), $\\bar{h}$. Three types of\nparticle dynamics are observed on varying activity and SU. For small $v_0\n\\lesssim 0.1$ and $\\bar{h}$ $\\gtrsim 0.8$, particles remain confined in a\nsurface minimum, for moderate $v_0 \\lesssim \\bar{h}$, dynamics of particle\nshows an intermediate subdiffusion to late time diffusion and for large $v_0\n\\gtrsim \\bar{h}$, it shows initial superdiffusion to late time diffusion. For\nall $v_0$'s and $\\bar{h} \\lesssim 0.2$, the dynamics of particle, satisfies the\nGreen-Kubo relation between the effective diffusivity and velocity\nauto-correlation function. Systematic deviation is found on increasing\n$\\bar{h}$. Hence, an effective equilibrium can be established for a range of\nsystem parameters in this nonequilibirum system."
    },
    {
        "anchor": "The irreversible thermodynamics of curved lipid membranes: The theory of irreversible thermodynamics for arbitrarily curved lipid\nmembranes is presented here. The coupling between elastic bending and\nirreversible processes such as intra-membrane lipid flow, intra-membrane phase\ntransitions, and protein binding and diffusion is studied. The forms of the\nentropy production for the irreversible processes are obtained, and the\ncorresponding thermodynamic forces and fluxes are identified. Employing the\nlinear irreversible thermodynamic framework, the governing equations of motion\nalong with appropriate boundary conditions are provided.",
        "positive": "Inverted Sedimentation of Active Particles in Unbiased ac Fields: Gaining control over the motion of active particles is crucial for\napplications ranging from targeted cargo delivery to nanomedicine. While much\nprogress has been made recently to control active motion based on external\nforces, flows or gradients in concentration or light intensity, which all have\na well-defined direction or bias, little is known about how to steer active\nparticles in situations where no permanent bias can be realized. Here, we show\nthat ac fields with a vanishing time average provide an alternative route to\nsteering active particles. We exemplify this route for inertial active\nparticles in a gravitational field, observing that a substantial fraction of\nthem persistently travels in the upward direction upon switching on the ac\nfield, resulting in an inverted sedimentation profile at the top wall of a\nconfining container. Our results offer a generic control principle which could\nbe used in the future to steer active motion, to direct collective behaviors\nand to purify mixtures."
    },
    {
        "anchor": "Unavoidable emergent biaxiality in chiral molecular-colloidal hybrid\n  liquid crystals: Chiral nematic or cholesteric liquid crystals (LCs) are mesophases with\nlong-ranged orientational order featuring a quasi-layered periodicity imparted\nby a helical configuration but lacking positional order. Doping molecular\ncholesteric LCs with thin colloidal rods with a large length-to-width ratio or\ndisks with a large diameter-to-thickness ratio adds another level of complexity\nto the system because of the interplay between weak surface boundary conditions\nand bulk-based elastic distortions around the particle-LC interface. By using\ncolloidal disks and rods with different geometric shapes and boundary\nconditions, we demonstrate that these anisotropic colloidal inclusions exhibit\nbiaxial orientational probability distributions, where they tend to orient with\nthe long rod axes and disk normals perpendicular to the helix axis, thus\nimparting strong local biaxiality on the hybrid cholesteric LC structure.\nUnlike the situation in achiral hybrid molecular-colloidal LCs, where biaxial\norder emerges only at modest to high volume fractions of the anisotropic\ncolloidal particles, the orientational probability distribution of colloidal\ninclusions immersed in chiral nematic hosts are unavoidably biaxial even at\nvanishingly low particle volume fractions. In addition, the colloidal\ninclusions induce local biaxiality in the molecular orientational order of the\nLC host medium, which enhances the weak biaxiality of the LC in a chiral\nnematic phase coming from the symmetry breaking caused by the presence of the\nhelical axis. With analytical modeling and computer simulations based on\nminimizing the Landau de Gennes free energy of the host LC around the\ncolloidals, we explain our experimental findings and conclude that the biaxial\norder of chiral molecular-colloidal LCs is strongly enhanced as compared to\nboth achiral molecular-colloidal LCs and molecular cholesteric LCs and is\nrather unavoidable.",
        "positive": "Brownian motion and the hydrodynamic friction tensor for colloidal\n  particles of complex shape: We synthesize colloidal particles with various anisotropic shapes and track\ntheir orientationally resolved Brownian trajectories using confocal microscopy.\nAn analysis of appropriate short-time correlation functions provides direct\naccess to the hydrodynamic friction tensor of the particles revealing\nnontrivial couplings between the translational and rotational degrees of\nfreedom. The results are consistent with calculations of the hydrodynamic\nfriction tensor in the low-Reynolds-number regime for the experimentally\ndetermined particle shapes."
    },
    {
        "anchor": "Nematic and smectic liquid crystals modeling with stiff and free-joint\n  Lennard-Jones chain molecules: Liquid crystals (LCs) composed of mesogens play important roles in various\nscientific and engineering problems. How a system with many mesogens can enter\na LC state is an interesting and important problem. Using stiff and free-joint\nLennard-Jones chain molecules as mesogens, we study the conditions under which\nthe mesogens can enter various LC phases. The guideline is to eliminate the\nunwanted translational orders under a controlled fine-tuning procedure across a\nsequence of systems. Instead of monitoring the growth of order out of the\ndisorder, we prepare a configuration of high orientation ordering and find out\nwhere it relaxes to. Such a procedure begins with a reference system,\nconsisting of short chains of homogeneous soft spheres, in a liquid-vapor\ncoexistence situation, at which the thermodynamic instability triggers a fast\nspontaneous growing process. By applying a short pulse of auxiliary field to\nalign the dispersedly oriented clusters, followed by reducing the volume and,\nfinally, changing the homogeneous molecules into heterogeneous chains, we are\nable to obtain a range of systems, including nematic and smectic LCs, at their\nstable ordered states. The model can be extended to study the influence of\nnanoparticles or external field on the LC structure.",
        "positive": "Role of cavitation in drying cementitious materials: This study aims to identify and isolate the role of properties of water with\nrespect to the shape of the first desorption isotherm of hardened cement\npastes. It has been observed that desorption occurs not only by receding\nmeniscus but is also affected by cavitation. Classical nucleation theory was\nused to understand and examine parameters that influence cavitation. The\nresults show that the sudden moisture loss at 0.3 pv psat in desorption\nisotherm occurs due to homogeneous cavitation. Further investigations revealed\nthat homogeneous cavitation occurs in the part of gel porosity that is\ndisconnected from the rest of capillary pores in the pore network."
    },
    {
        "anchor": "Binding self-propelled topological defects in active turbulence: We report on the emergence of stable self-propelled bound defects in\nmonolayers of active nematics, which form virtual full-integer topological\ndefects in the form of vortices and asters. Through numerical simulations and\nanalytical arguments, we identify the phase-space of the bound defect formation\nin active nematic monolayers. It is shown that an intricate synergy between the\nnature of active stresses and the flow-aligning behaviour of active particles\ncan stabilise the motion of self-propelled positive half-integer defects into\nspecific bound structures. Our findings uncover new complexities in active\nnematics with potential for triggering new experiments and theories.",
        "positive": "Crystal Nucleation of Highly-Screened Charged Colloids: We study the nucleation of nearly-hard charged colloidal particles. We use\nMonte Carlo simulations in combination with free-energy calculations to\naccurately predict the phase diagrams of these particles and map them via the\nfreezing density to hard spheres, then we use umbrella sampling to explore the\nnucleation process. Surprisingly, we find that even very small amounts of\ncharge can have a significant effect on the phase behavior. Specifically, we\nfind that phase boundaries and nucleation barriers are mostly dependent on the\nDebye screening length, and that even screening lengths as small as 2% of the\nparticle diameter are sufficient to show marked differences in both. This work\ndemonstrates clearly that even mildly charged colloids are not effectively hard\nspheres."
    },
    {
        "anchor": "Aging and metastability of monoglycerides in hydrophobic solutions: The aging of aggregated structures of monoglycerides in hydrophobic medium is\ndescribed by a set of different techniques. Polarized microscopy was used to\nstudy the mesomorphic behavior as a function of time. Differential scanning\ncalorimetry was utilized to quantitatively monitor changes in the latent heat\nin different phase transformations that take place in the aging system.\nInfrared spectroscopy was applied to detect the formation of hydrogen bonding\nbetween surfactants. The X-ray diffraction patterns fingerprinted the molecular\narrangement in different emerging phases. Infra-red spectroscopy was used to\nmonitor the state of hydrogen bonding in the system. We conclude that in both\ninverted-lamellar and sub-alpha crystalline phases, monoglyceride molecules\ninevitably lose their emulsified ability in the hydrophobic solutions through\nthe gradual change in hydrogen bonding patterns. On aging, the formation of\nintermolecular hydrogen bonding between glycerol groups causes the segregation\nof chiral (D and L) isomers within the bilayers. Therefore all structures were\neventually forced to reorder into the beta-crystalline state, distinguishing\nbetween the D and L layers. Accordingly, the highly ordered packing of aged\nstructures weakened the emulsifying ability and finally leaded the collapse of\nthe percolating gel network.",
        "positive": "Strong pretransitional anomaly near glass transition: In this report we present the first ever results of strong pretransitional\neffect observed for the maximum of absorption peak $${\\epsilon}_{max}^{''}(T)$$\nin supercooled liquid-crystalline systems near the glass transition\ntemperature. This anomaly may be described by critical-like relation with\ncritical exponent {\\alpha}=0.5, which corresponds well with previous results\nfor static electric permittivity $${\\epsilon}_{s}(T)$$. Such a behaviour may\nsuggest thermodynamic character of glass transition."
    },
    {
        "anchor": "Dynamics of bright matter-wave solitons in inhomogeneous cigar-type\n  Bose-Einstein condensate: We discuss the possible observation of a new type of standing nonlinear\natomic matter wave in the condensate: the nonlinear impurity mode. It is\ninvestigated dynamical effects of a bright soliton in Bose-Einstein-condensed\n(BEC) systems with local space variations of the two-body atomic scattering\nlength. A rich dynamics is observed in the interaction between the soliton and\nan inhomogeneity. Processes as trapping, reflection and transmission of the\nbright matter soliton due to the impurity are studied considering an analytical\ntime-dependent variational approach and also by full numerical simulation. A\ncondition is obtained for the collapse of the bright solitary wave in the\nquasi-one-dimensional BEC with attractive local inhomogeneity.",
        "positive": "Effects of nonlinearity in wave propagation in multicomponent\n  Bose-Einstein condensates: We consider a spinor Bose-Einstein condensate in its polar ground state. We\nanalyze magnetization waves of a finite amplitude and show that their nonlinear\ncoupling to the density waves change the dependence of the frequency on the\nwavenumber dramatically. In contrary, the density wave propagation is much less\nmodified by the nonlinearity effects. A similar phenomenon in a miscible\ntwo-component condensate is studied, too."
    },
    {
        "anchor": "Flow states of two dimensional active gels driven by external shear: Using a minimal hydrodynamic model, we theoretically and computationally\nstudy active gels in straight and annular two-dimensional channels subject to\nan externally imposed shear. The gels are isotropic in the absence of\nexternally- or activity-driven shear, but have nematic order that increases\nwith shear rate. Using the finite element method, we determine the possible\nflow states for a range of activities and shear rates. Linear stability\nanalysis of an unconfined gel in a straight channel shows that an externally\nimposed shear flow can stabilize an extensile fluid that would be unstable to\nspontaneous flow in the absence of the shear flow, and destabilize a\ncontractile fluid that would be stable against spontaneous flow in the absence\nof shear flow. These results are in rough agreement with the stability\nboundaries between the base shear flow state and the nonlinear flow states that\nwe find numerically for a confined active gel. For extensile fluids, we find\nthree kinds of nonlinear flow states in the range of parameters we study:\nunidirectional flows, oscillatory flows, and dancing flows. To highlight the\nactivity-driven spontaneous component of the nonlinear flows, we characterize\nthese states by the average volumetric flow rate and the wall stress. For\ncontractile fluids, we only find the linear shear flow and a nonlinear\nunidirectional flow in the range of parameters that we studied. For large\nmagnitudes of the activity, the unidirectional contractile flow develops a\nboundary layer. Our analysis of annular channels shows how curvature of the\nstreamlines in the base flow affects the transitions among flow states.",
        "positive": "Instability cascades in disordered systems indicate record dynamics: In Shohat et al. [1], the authors present a study of the aging dynamics for\ncrumpling sheets of mylar after a constant load is applied. Those experiments\nare modeled with molecular dynamics (MD) simulations of a network of randomly\nbistable elements. While such a specific model may well account for the\nmicroscopic origins of the aging phenomenology in a large class of disordered\nsystems, we note that the observed temporal behavior is far more universal [2,\n3, 4]. We show here that it is but another example of a system generically\nexhibiting a statistic of records (i.e., record dynamics) that can be analyzed\nas a log-Poisson process [5], an effective means to discriminate between models\n[6]. To this end, we can defer to the keen observations by the authors as well\nas employ the LAMMPS [7] script they have provided."
    },
    {
        "anchor": "Pollen Patterns Form from Modulated Phases: Pollen grains are known for their impressive variety of species-specific,\nmicroscale surface patterning. Despite having similar biological developmental\nsteps, pollen grain surface features are remarkably geometrically varied.\nPrevious work suggests that a physical process may drive this pattern formation\nand that the observed diversity of patterns can be explained by viewing pollen\npattern development as a phase transition to a spatially modulated phase.\nSeveral studies have shown that the polysaccharide material of plant cell walls\nundergoes phase separation in the absence of cross-linking stabilizers of the\nmixed phase. Here we show experimental evidence of a change in density of the\nextracellular polysaccharide material (primexine) during pollen cell\ndevelopment leads to a spatially modulated phase. The spatial pattern of this\nphase-separated primexine is also mechanically coupled to the undulation of the\npollen cell membrane. The resulting patterned pools of denser primexine form\nthe negative template of the ultimate sites of sporopollenin deposition,\nleading to the final micropattern observed in the mature pollen. We then\npresent a general physical model of pattern formation via modulated phases.\nUsing analytical and numerical techniques, we find that most of the pollen\nmicropatterns observed in biological evolution could result from a physical\nprocess of modulated phases. However, an analysis of the relative rates of\ntransitions from states that are equilibrated to or from states that are not\nequilibrated suggests that while equilibrium states of this process have\noccurred throughout evolutionary history, there has been no particular\nevolutionary selection for distinctly patterned equilibrated states.",
        "positive": "Work and dissipation fluctuations near the stochastic resonance of a\n  colloidal particle: We study experimentally the fluctuations of the injected and dissipated\nenergy in a system of a colloidal particle trapped in a double well potential\nperiodically modulated by an external perturbation. The work done by the\nexternal force and the dissipated energy are measured close to the stochastic\nresonance where the injected power is maximum. We show that the steady state\nfluctuation theorem holds in this system."
    },
    {
        "anchor": "Orientational Dynamics of Fluctuating Dipolar Particles Assembled in a\n  Mesoscopic Colloidal Ribbon: We combine experiments and theory to investigate the dynamics and\norientational fluctuations of ferromagnetic microellipsoids that form a\nribbon-like structure due to attractive dipolar forces. When assembled in the\nribbon, the ellipsoids displays orientational thermal uctuations with an\namplitude that can be controlled via application of an in-plane magnetic field.\nWe use video microscopy to investigate the orientational dynamics in real\ntime/space. Theoretical arguments are used to derive an analytical expression\nthat describes how the distribution of the different angular configurations\ndepends on the strength of the applied field. The experimental data are in good\nagreement with the developed model for all the range of field parameters\nexplored. Understanding the role of uctuations in chains composed of dipolar\nparticles is important not only from a fundamental point of view, but it may\nalso help understanding the stability of such structures against thermal noise,\nwhich is relevant in micro uidics and lab-on-a-chip applications.",
        "positive": "Effects of polymer polydispersity on the phase behaviour of\n  colloid-polymer mixtures: We study the equilibrium behaviour of a mixture of monodisperse hard sphere\ncolloids and polydisperse non-adsorbing polymers at their $\\theta$-point, using\nthe Asakura-Oosawa model treated within the free-volume approximation. Our\nfocus is the experimentally relevant scenario where the distribution of polymer\nchain lengths across the system is fixed. Phase diagrams are calculated using\nthe moment free energy method, and we show that the mean polymer size $\\xi_{\\rm\nc}$ at which gas-liquid phase separation first occurs decreases with increasing\npolymer polydispersity $\\delta$. Correspondingly, at fixed mean polymer size,\npolydispersity favours gas-liquid coexistence but delays the onset of\nfluid-solid separation. On the other hand, we find that systems with different\n$\\delta$ but the same {\\em mass-averaged} polymer chain length have nearly\npolydispersity-independent phase diagrams. We conclude with a comparison to\nprevious calculations for a semi-grandcanonical scenario, where the polymer\nchemical potentials are imposed, which predicted that fluid-solid coexistence\nwas over gas-liquid in some areas of the phase diagram. Our results show that\nthis somewhat counter-intuitive result arose because the actual polymer size\ndistribution in the system is shifted to smaller sizes relative to the polymer\nreservoir distribution."
    },
    {
        "anchor": "Structural Determinant of Protein Designability: Here we present an approximate analytical theory for the relationship between\na protein structure's contact matrix and the shape of its energy spectrum in\namino acid sequence space. We demonstrate a dependence of the number of\nsequences of low energy in a structure on the eigenvalues of the structure's\ncontact matrix, and then use a Monte Carlo simulation to test the applicability\nof this analytical result to cubic lattice proteins. We find that the lattice\nstructures with the most low-energy sequences are the same as those predicted\nby the theory. We argue that, given sufficiently strict requirements for\nfoldability, these structures are the most designable, and we propose a simple\nmeans to test whether the results in this paper hold true for real proteins.",
        "positive": "Does the Sastry transition control cavitation in simple liquids?: We examine the Sastry (athermal cavitation) transitions for model monatomic\nliquids interacting via Lennard-Jones as well as shorter- and longer-ranged\npair potentials. Low-temperature thermodynamically stable liquids have $\\rho <\n\\rho_S$ except when the attractive forces are long-ranged. For moderate- and\nshort-ranged attractions, stable liquids with $\\rho > \\rho_S$ exist at higher\ntemperatures; the pressures in these liquids are high, but the Sastry\ntransition may strongly influence their cavitation under dynamic hydrostatic\nexpansion. The temperature $T^*$ at which stable $\\rho > \\rho_S$ liquids emerge\nis $\\sim 0.84\\epsilon/k_B$ for Lennard-Jones liquids; $T^*$ decreases\n(increases) rapidly with increasing (decreasing) pair-interaction range. In\nparticular, for short-ranged potentials, $T^*$ is above the critical\ntemperature. All liquids' inherent structures are isostructural (isomorphic)\nfor densities below (above) the Sastry density $\\rho_S$. Overall, our results\nsuggest that the barriers to cavitation in most simple liquids under ambient\nconditions where significant cavitation is likely to occur are primarily\nvibrational-energetic and entropic rather than configurational-energetic. The\nmost likely exceptions to this rule are liquids with long-ranged pair\ninteractions, such as alkali metals. The most likely exceptions to this rule\nare liquids with long-ranged pair interactions, such as alkali metals."
    },
    {
        "anchor": "Hydrodynamic correlation functions of chiral active fluids: The success of spectroscopy to characterise equilibrium fluids, for example\nthe heat capacity ratio, suggests a parallel approach for active fluids. Here,\nwe start from a hydrodynamic description of chiral active fluids composed of\nspinning constituents and derive their low-frequency, long-wavelength response\nfunctions using the Kadanoff-Martin formalism. We find that the presence of odd\n(equivalently, Hall) viscosity leads to mixed density-vorticity response even\nat linear order. Such response, prohibited in time-reversal-invariant fluids,\nis a large-scale manifestation of the microscopic breaking of time-reversal\nsymmetry. Our work suggests possible experimental probes that can measure\nanomalous transport coefficients in active fluids through dynamic light\nscattering.",
        "positive": "Impact of loop statistics on the thermodynamics of RNA folding: Loops are abundant in native RNA structures and proliferate close to the\nunfolding transition. By including a statistical weight ~ l^{-c} for loops of\nlength l in the recursion relation for the partition function, we show that the\ncalculated heat capacity depends sensitively on the presence and value of the\nexponent c, even of short t-RNA. For homo-RNA we analytically calculate the\ncritical temperature and critical exponents which exhibit a non-universal\ndependence on c."
    },
    {
        "anchor": "Theory of rigidity and numerical analysis of density of states of\n  two-dimensional amorphous solids with dispersed frictional grains in the\n  linear response regime: Using the Jacobian matrix, we obtain theoretical expression of rigidity and\nthe density of states of two-dimensional amorphous solids consisting of\nfrictional grains in the linear response to an infinitesimal strain, in which\nwe ignore the dynamical friction caused by the slip processes of contact\npoints. The theoretical rigidity agrees with that obtained by molecular\ndynamics simulations. We confirm that the rigidity is smoothly connected to the\nvalue in the frictionless limit. For the density of states, we find that there\nare two modes in the density of states for sufficiently small $k_{T}/k_{N}$,\nwhich is the ratio of the tangential to normal stiffness. Rotational modes\nexist at low frequencies or small eigenvalues, whereas translational modes\nexist at high frequencies or large eigenvalues. The location of the rotational\nband shifts to the high-frequency region with an increase in $k_{T}/k_{N}$ and\nbecomes indistinguishable from the translational band for large $k_{T}/k_{N}$.\nThe rigidity determined by the translational modes agrees with that obtained by\nthe molecular dynamics simulations, whereas the contribution of the rotational\nmodes is almost zero for small $k_{T}/k_{N}$.",
        "positive": "Dense packings of hard circular arcs: This work investigates dense packings of congruent hard infinitesimally--thin\ncircular arcs in the two-dimensional Euclidean space. It focuses on those\ndenotable as major whose subtended angle $\\theta \\in \\left ( \\pi, 2\\pi \\right\n]$. Differently than those denotable as minor whose subtended angle $\\theta \\in\n\\left [0, \\pi \\right]$, it is impossible for two hard infinitesimally-thin\ncircular arcs with $\\theta \\in \\left ( \\pi, 2\\pi \\right ]$ to arbitrarily\nclosely approach once they are arranged in a configuration, e.g. on top of one\nanother, replicable ad infinitum without introducing any overlap. This makes\nthese hard concave particles, in spite of being infinitesimally thin, most\ndensely pack with a finite number density. This raises the question as to what\nare these densest packings and what is the number density that they achieve.\nSupported by Monte Carlo numerical simulations, this work shows that one can\nanalytically construct compact closed circular groups of hard major circular\narcs in which a specific, $\\theta$-dependent, number of them (anti-)clockwise\nintertwine. These compact closed circular groups then arrange on a triangular\nlattice. These analytically constructed densest-known packings are compared to\ncorresponding results of Monte Carlo numerical simulations to assess whether\nthey can spontaneously turn up."
    },
    {
        "anchor": "Transitions among crystal, glass, and liquid in a binary mixture with\n  changing particle size ratio and temperature: Using molecular dynamics simulation we examine changeovers among crystal,\nglass, and liquid at high density in a two dimensional binary mixture. We\nchange the ratio between the diameters of the two components and the\ntemperature. The transitions from crystal to glass or liquid occur with\nproliferation of defects. We visualize the defects in terms of a disorder\nvariable \"D_j(t)\" representing a deviation from the hexagonal order for\nparticle j. The defect structures are heterogeneous and are particularly\nextended in polycrystal states. They look similar at the crystal-glass\ncrossover and at the melting. Taking the average of \"D_j(t)\" over the\nparticles, we define a disorder parameter \"D(t)\", which conveniently measures\nthe degree of overall disorder. Its relaxation after quenching becomes slow at\nlow temperature in the presence of size dispersity. Its steady state average is\nsmall in crystal and large in glass and liquid.",
        "positive": "A model for the Pockels effect in distorted liquid crystal blue phases: Recent experiments have found that a mechanically distorted blue phase can\nexhibit a primary linear electro-optic (Pockels) effect [F. Castles \\textit{et\nal}. Nature Mater. \\textbf{13}, 817 (2014)]. Here it is shown that\nflexoelectricity can account for the experimental results and a model, which is\nbased on continuum theory but takes account of the sub-unit-cell structure, is\nproposed. The model provides a quantitative description of the effect accurate\nto the nearest order of magnitude and predicts that the Pockels coefficient(s)\nin an optimally-distorted blue phase may be two orders of magnitude larger than\nin lithium niobate."
    },
    {
        "anchor": "Rigid clusters in shear-thickening suspensions: a nonequilibrium\n  critical transition: The onset and growth of rigid clusters in a two-dimensional (2D) suspension\nin shear flow are studied by numerical simulation. The suspension exhibits the\nlubricated-to-frictional rheology transition but is studied at stresses above\nthe levels that cause extreme shear thickening. At large solid area fraction,\n$\\phi$, but below the jamming fraction, we find that there is critical $\\phi_c$\nbeyond which the proportion of particles in rigid clusters grows sharply, as\n$f_{\\rm rig} \\sim (\\phi-\\phi_c)^{\\beta}$ with $\\beta=1/8$, and at which the\nfluctuations in the net rigidity grow sharply, with a susceptibility measure\n$\\chi_{\\rm rig} \\sim |\\phi-\\phi_c|^{-\\gamma}$ with $\\gamma = 7/4$. By applying\nfinite size scaling, the correlation length, arising from the correlation of\nrigid domains, is found to scale as $\\xi \\sim |\\phi-\\phi_c|^{-\\nu}$ with $\\nu =\n1$. The system is thus found to exhibit criticality, with critical exponents\nconsistent with the 2D Ising transition. This behavior occurs over a range of\nstresses, with $\\phi_c$ increasing as the stress decreases, consistent with the\nknown increase in jamming fraction with reduction of stress for\nshear-thickening suspensions.",
        "positive": "Higher order glass-transition singularities in colloidal systems with\n  attractive interactions: The transition from a liquid to a glass in colloidal suspensions of particles\ninteracting through a hard core plus an attractive square-well potential is\nstudied within the mode-coupling-theory framework. When the width of the\nattractive potential is much shorter than the hard-core diameter, a reentrant\nbehavior of the liquid-glass line, and a glass-glass-transition line are found\nin the temperature-density plane of the model. For small well-width values, the\nglass-glass-transition line terminates in a third order bifurcation point, i.e.\nin a A_3 (cusp) singularity. On increasing the square-well width, the\nglass-glass line disappears, giving rise to a fourth order A_4 (swallow-tail)\nsingularity at a critical well width. Close to the A_3 and A_4 singularities\nthe decay of the density correlators shows stretching of huge dynamical\nwindows, in particular logarithmic time dependence."
    },
    {
        "anchor": "Signature of jamming under steady shear in dense particulate suspensions: Under an increasing applied shear stress ($\\sigma$), viscosity of many dense\nparticulate suspensions increases drastically beyond a stress onset\n($\\sigma_0$), a phenomenon known as discontinuous shear-thickening (DST).\nRecent studies point out that some suspensions can transform into a stress\ninduced solid-like shear jammed (SJ) state at high particle volume fraction\n($\\phi$). SJ state develops a finite yield stress and hence is distinct from a\nshear-thickened state. Here, we study the steady state shear-thickening\nbehaviour of dense suspensions formed by dispersing colloidal polystyrene\nparticles (PS) in polyethylene glycol (PEG). We find that for small $\\sigma$\nvalues the viscosity of the suspensions as a function of $\\phi$ can be well\ndescribed by Krieger-Dougherty (KD) relation. However, for higher values of\n$\\sigma$ ($>> \\sigma_0$), KD relation systematically overestimates the measured\nviscosity, particularly for higher $\\phi$ values. This systematic deviation can\nbe rationalized by the weakening of the sample due to flow induced failures of\nthe solid-like SJ state. Using Wyart-Cates model, we propose a method to\npredict the SJ onset from the steady state rheology measurements. Our results\nare further supported by in-situ optical imaging of the sample boundary under\nshear.",
        "positive": "The competition of hydrogen-like and isotropic interactions on polymer\n  collapse: We investigate a lattice model of polymers where the nearest-neighbour\nmonomer-monomer interaction strengths differ according to whether the local\nconfigurations have so-called ``hydrogen-like'' formations or not. If the\ninteraction strengths are all the same then the classical $\\theta$-point\ncollapse transition occurs on lowering the temperature, and the polymer enters\nthe isotropic liquid-drop phase known as the collapsed globule. On the other\nhand, strongly favouring the hydrogen-like interactions give rise to an\nanisotropic folded (solid-like) phase on lowering the temperature. We use Monte\nCarlo simulations up to a length of 256 to map out the phase diagram in the\nplane of parameters and determine the order of the associated phase\ntransitions. We discuss the connections to semi-flexible polymers and other\npolymer models. Importantly, we demonstrate that for a range of energy\nparameters two phase transitions occur on lowering the temperature, the second\nbeing a transition from the globule state to the crystal state. We argue from\nour data that this globule-to-crystal transition is continuous in two\ndimensions in accord with field-theory arguments concerning Hamiltonian walks,\nbut is first order in three dimensions."
    },
    {
        "anchor": "Rotating Hele-Shaw cells with ferrofluids: We investigate the flow of two immiscible, viscous fluids in a rotating\nHele-Shaw cell, when one of the fluids is a ferrofluid and an external magnetic\nfield is applied. The interplay between centrifugal and magnetic forces in\ndetermining the instability of the fluid-fluid interface is analyzed. The\nlinear stability analysis of the problem shows that a non-uniform, azimuthal\nmagnetic field, applied tangential to the cell, tends to stabilize the\ninterface. We verify that maximum growth rate selection of initial patterns is\ninfluenced by the applied field, which tends to decrease the number of\ninterface ripples. We contrast these results with the situation in which a\nuniform magnetic field is applied normally to the plane defined by the rotating\nHele-Shaw cell.",
        "positive": "At least three invariants are necessary to model the mechanical response\n  of incompressible, transversely isotropic materials: The modelling of off-axis simple tension experiments on transversely\nisotropic nonlinearly elastic materials is considered. A testing protocol is\nproposed where normal force is applied to one edge of a rectangular specimen\nwith the opposite edge allowed to move laterally but constrained so that no\nvertical displacement is allowed. Numerical simulations suggest that this\ndeformation is likely to remain substantially homogeneous throughout the\nspecimen for moderate deformations. It is therefore further proposed that such\ntests can be modelled adequately as a homogenous deformation consisting of a\ntriaxial stretch accompanied by a simple shear. Thus the proposed test should\nbe a viable alternative to the standard biaxial tests currently used as\nmaterial characterisation tests for transversely isotropic materials in general\nand, in particular, for soft, biological tissue. A consequence of the analysis\nis a kinematical universal relation for off-axis testing that results when the\nstrain-energy function is assumed to be a function of only one isotropic and\none anisotropic invariant, as is typically the case. The universal relation\nprovides a simple test of this assumption, which is usually made for\nmathematical convenience. Numerical simulations also suggest that this\nuniversal relation is unlikely to agree with experimental data and therefore\nthat at least three invariants are necessary to fully capture the mechanical\nresponse of transversely isotropic materials."
    },
    {
        "anchor": "Multiple reentrant glass transitions in confined hard-sphere glasses: Glass forming liquids exhibit a rich phenomenology upon confinement. This is\noften related to the effects arising from wall-fluid interactions. Here we\nfocus on the interesting limit where the separation of the confining walls\nbecomes of the order of a few particle diameters. For a moderately\npolydisperse, densely packed hard-sphere fluid confined between two smooth hard\nwalls, we show via event-driven molecular dynamics simulations the emergence of\na multiple reentrant glass transition scenario upon a variation of the wall\nseparation. Using thermodynamic relations, this reentrant phenomenon is shown\nto persist also under constant chemical potential. This allows straightforward\nexperimental investigation and opens the way to a variety of applications in\nmicro- and nanotechnology, where channel dimensions are comparable to the size\nof the contained particles. The results are in-line with theoretical\npredictions obtained by a combination of density functional theory and the\nmode-coupling theory of the glass transition.",
        "positive": "Phase diagrams and crystal-fluid surface tensions in additive and\n  nonadditive two-dimensional hard disk mixtures: Using density functionals from fundamental measure theory, phase diagrams and\ncrystal-fluid surface tensions in additive and nonadditive (Asakura-Oosawa\nmodel) two-dimensional hard disk mixtures are determined for the whole range of\nsize ratios $q$ between disks, assuming random disorder in the crystal phase.\nThe fluid-crystal transitions are first-order due to the assumption of a\nperiodic unit cell in the density functional calculations. Qualitatively, the\nshape of the phase diagrams is similar to the case of three-dimensional hard\nsphere mixtures. For the nonadditive case, a broadening of the fluid-crystal\ncoexistence region is found for small $q$ whereas for higher $q$ a vapor--fluid\ntransition intervenes. In the additive case, we find a sequence of spindle\ntype, azeotropic and eutectic phase diagrams upon lowering $q$ from 1 to 0.6.\nThe transition from azeotropic to eutectic is different from the\nthree-dimensional case. Surface tensions in general become smaller (up to a\nfactor 2) upon addition of a second species and they are rather small. The\nminimization of the functionals proceeds without restrictions and optimized\ngraphics card routines are used."
    },
    {
        "anchor": "Serum protein resistant behavior of multisite-bound poly(ethylene\n  glycol) chains onto iron oxide surfaces: Recent surveys have shown that the number of nanoparticle-based formulations\nactually used at the clinical level is significantly lower than expected a\ndecade ago. One reason for this is that the nanoparticle physicochemical\nproperties fall short for handling the complexity of biological environments\nand for preventing nonspecific protein adsorption. In this study, we address\nthe issue of the interactions of plasma proteins with polymer coated surfaces.\nTo this aim, we use a non-covalent grafting-to method to functionalize iron\noxide sub-10 nm nanoparticles and iron oxide flat substrates, and compare their\nprotein responses. The functionalized copolymers consist in alternating\npoly(ethylene glycol) (PEG) chains and phosphonic acid grafted on the same\nbackbone. Quartz Crystal Microbalance with dissipation was used to monitor the\npolymer adsorption kinetics and to evaluate the resistance to protein\nadsorption. On flat substrates, functionalized PEG copolymers adsorb and form a\nbrush in the moderate or in the highly stretched regimes, with density between\n0.15 and 1.5 nm-2. PEG layers using phosphonic acid as linkers exhibit\nexcellent protein resistance. In contrast, layers prepared with carboxylic acid\nas grafting agent exhibit mitigated protein responses and layer\ndestructuration. The present study establishes a correlation between the\nlong-term stability of PEG coated particles in biofluids and the protein\nresistance of surfaces coated with the same polymers.",
        "positive": "Temperature dependence of the transition packing fraction of thermal\n  jamming in a harmonic soft sphere system: The glassy dynamics of soft harmonic spheres is often mapped onto the\ndynamics of hard spheres by considering an effective diameter for the soft\nparticles and therefore an effective packing fraction. While in this approach\nthe thermal fluctuations within valleys of the energy landscape are covered,\nthe crossing of energy barriers from one valley into another usually is\nneglected. Here we argue - motivated by studies of the glass transition based\non explorations of the energy landscape - that the crossing of energy barriers\ncan be attributed by an effective decrease of the glass transition packing\nfraction with increasing temperature T according to T^{0.2}. Furthermore, we\nreanalyzing data of soft sphere simulations. Since fitting scaling laws to\nsimulation data always allows for some arbitrariness, we cannot prove based on\nthe simulation data that our idea of a shift of the glass transition packing\nfraction due to barrier crossings is the only possible way to explain the\ndiscrepancies that have been observed previously. However, we show that a\npossible explanation of the simulation data is given by our approach to\ncharacterize the dynamics of soft spheres by both, the previously-considered\ntemperature-dependent effective packing fraction due to the increase of the\nmean overlap between neighboring particles with stronger thermal fluctuations\nand the newly introduced increase of the glass transition packing with an\nincreasing probability of barrier crossings."
    },
    {
        "anchor": "Mean-field theory of active electrolytes: dynamic adsorption and\n  overscreening: We investigate active electrolytes within the mean-field level of\ndescription. The focus is on how the double-layer structure of passive,\nthermalized charges is affected by active dynamics of all constituting ions.\nOne feature of active dynamics is that particles adhere to hard-surfaces,\nregardless of chemical properties of a surface and specifically in complete\nabsence of any chemipsorption or physisorption. To carry out the mean-field\nanalysis of the system that is out of equilibrium, we develop the \"mean-field\nsimulation\" technique, where the simulated system consists of charged parallel\nsheets moving on a line and obeying active dynamics, with the interaction\nstrength rescaled by the number of sheets. The mean-field limit becomes exact\nin the limit of an infinite number of movable sheets.",
        "positive": "Geometry-induced asymmetric diffusion: Past work has shown that ions can pass through a membrane more readily in one\ndirection than the other. We demonstrate here in a model and an experiment that\nfor a mixture of small and large particles such asymmetric diffusion can arise\nsolely from an asymmetry in the geometry of the pores of the membrane. Our\ndeterministic simulation considers a two-dimensional gas of elastic disks of\ntwo sizes diffusing through a membrane, and our laboratory experiment examines\nthe diffusion of glass beads of two sizes through a metal membrane. In both\nexperiment and simulation, the membrane is permeable only to the smaller\nparticles, and the asymmetric pores lead to an asymmetry in the diffusion rates\nof these particles. The presence of even a small percentage of large particles\ncan clog a membrane, preventing passage of the small particles in one direction\nwhile permitting free flow of the small particles in the other direction. The\npurely geometric kinetic constraints may play a role in common biological\ncontexts such as membrane ion channels."
    },
    {
        "anchor": "Mean-Field Predictions of Scaling Prefactors Match Low-Dimensional\n  Jammed Packings: No known analytic framework precisely explains all the phenomena observed in\njamming. The replica theory for glass and jamming is a mean field theory which\nattempts to do so by working in the limit of infinite dimensions, such that\ncorrelations between neighbors are negligible. As such, results from this mean\nfield theory are not guaranteed to be observed in finite dimensions. However,\nmany results in mean field for jamming have been shown to be exact or nearly\nexact in low dimensions. This suggests that the infinite dimensional limit is\nnot necessary to obtain these results. In this paper, we perform precision\nmeasurements of jamming scaling relationships between pressure, excess packing\nfraction, and number of excess contacts from dimensions 2-10 in order to\nextract the prefactors to these scalings. While these prefactors should be\nhighly sensitive to finite dimensional corrections, we find the mean field\npredictions for these prefactors to be exact in low dimensions. Thus the mean\nfield approximation is not necessary for deriving these prefactors. We present\nan exact, first principles derivation for one, leaving the other as an open\nquestion.",
        "positive": "Self-attractive semiflexible polymers under an external force field: The dynamical response of a tethered semiflexible polymer with\nself-attractive interactions and subjected to an external force field is\nnumerically investigated by varying stiffness and self-interaction strength.\nThe chain is confined in two spatial dimensions and placed in contact with a\nheat bath described by the Brownian multiparticle collision method. For strong\nself-attraction the equilibrium conformations range from compact structures to\ndouble-stranded chains, and to rods when increasing the stiffness. Under the\nexternal field at small rigidities, the initial close-packed chain is\ncontinuously unwound by the force before being completely elongated. For\ndouble-stranded conformations the transition from the folded state to the open\none is sharp being steeper for larger stiffnesses. The discontinuity in the\ntransition appears in the force-extension relation as well as in the\nprobability distribution function of the gyration radius. The relative\ndeformation with respect to the equilibrium case along the direction normal to\nthe force is found to decay as the inverse of the applied force."
    },
    {
        "anchor": "Effect of Photon Counting Shot Noise on Total Internal Reflection\n  Microscopy: Total internal reflection microscopy (TIRM) measures changes in the distance\nbetween a colloidal particle and a transparent substrate by measuring the\nintensity of light scattered by the particle when it is illuminated by the\nevanescent field that is created from light totally internally reflected at the\nsubstrate interface. From these measurements, the height-dependent effective\npotential $\\varphi(z)$ between the colloidal particle and the substrate can be\nmeasured. The spatial resolution with which TIRM can resolve the height $z$ and\neffective potential $\\varphi(z)$ is limited by the intrinsic shot noise of the\nphoton counting process used to measure the scattered light intensity. We\ndevelop a model to determine the spatial resolution with which TIRM can measure\n$\\varphi(z)$ and verify its validity with simulations and experiments. We\nfurther establish the critical role of photon-counting statistics and the\nintensity integration time $\\tau$ in TIRM measurements, which is a trade-off\nbetween narrowing the width of the photon counting distribution and capturing\nthe instantaneous position of the probe particle.",
        "positive": "Polydisperse hard spheres at a hard wall: The structural properties of polydisperse hard spheres in the presence of a\nhard wall are investigated via Monte Carlo simulation and density functional\ntheory (DFT). Attention is focussed on the local density distribution\n$\\rho(\\sigma,z)$, measuring the number density of particles of diameter\n$\\sigma$ at a distance $z$ from the wall. The form of $\\rho(\\sigma,z)$ is\nobtained for bulk volume fractions $\\eta_b=0.2$ and $\\eta_b=0.4$ for two\nchoices of the bulk parent distribution: a top-hat form, which we study for\ndegrees of polydispersity $\\delta=11.5%$ and $\\delta=40.4%$, and a truncated\nSchulz form having $\\delta=40.7%$. Excellent overall agreement is found between\nthe DFT and simulation results, particularly at $\\eta_b=0.2$. A detailed\nanalysis of $\\rho(\\sigma,z)$ confirms the presence of oscillatory size\nsegregation effects observed in a previous DFT study (Pagonabarraga {\\em et\nal.}, Phys. Rev. Lett. {\\bf 84}, 911 (2000)). For large $\\delta$, the character\nof these oscillation is observed to depend strongly on the shape of the parent\ndistribution. In the vicinity of the wall, attractive $\\sigma$-dependent\ndepletion interactions are found to greatly enhance the density of the largest\nparticles. The local degree of polydispersity $\\delta(z)$ is suppressed in this\nregion, while further from the wall it exhibits oscillations."
    },
    {
        "anchor": "Deformation of an asymmetric thin film: Experiments have investigated shape changes of polymer films induced by\nasymmetric swelling by a chemical vapor. Inspired by recent work on the shaping\nof elastic sheets by non-Euclidean metrics [Y. Klein, E. Efrati, and E. Sharon,\nScience 315, 1116 (2007)], we represent the effect of chemical vapors by a\nchange in the target metric tensor. In this problem, unlike that earlier work,\nthe target metric is asymmetric between the two sides of the film. Changing\nthis metric induces a curvature of the film, which may be curvature into a\npartial cylinder or a partial sphere. We calculate the elastic energy for each\nof these shapes, and show that the sphere is favored for films smaller than a\ncritical size, which depends on the film thickness, while the cylinder is\nfavored for larger films.",
        "positive": "Mutation at Expanding Front of Self-Replicating Colloidal Clusters: We construct a scheme for self-replicating square clusters of particles in\ntwo spatial dimensions, and validate it with computer simulations in a\nfinite-temperature heat bath. We find that the self-replication reactions\npropagate through the bath in the form of Fisher waves. Our model reflects\nexisting colloidal systems, but is simple enough to allow simulation of many\ngenerations and thereby the first study of evolutionary dynamics in an\nartificial system. By introducing spatially localized mutations in the\nreplication rules, we show that the mutated cluster population can survive and\nspread with the expanding front in circular sectors of the colony."
    },
    {
        "anchor": "A Tree Swaying in a Turbulent Wind: A Scaling Analysis: A tentative scaling theory is presented of a tree swaying in a turbulent\nwind. It is argued that the turbulence of the air within the crown is in the\ninertial regime. An eddy causes a dynamic bending response of the branches\naccording to a time criterion. The resulting expression for the penetration\ndepth of the wind yields an exponent which appears to be consistent with that\npertaining to the morphology of the tree branches. An energy criterion shows\nthat the dynamics of the branches is basically passive. The possibility of\nhydrodynamic screening by the leaves is discussed.",
        "positive": "Electrophoresis of DNA on a disordered two-dimensional substrate: We propose a new method for electrophoretic separation of DNA in which\nadsorbed polymers are driven over a disordered two-dimensional substrate which\ncontains attractive sites for the polymers. Using simulations of a model for\nlong polymer chains, we show that the mobility increases with polymer length,\nin contrast to gel electrophoresis techniques, and that separation can be\nachieved for a range of length scales. We demonstrate that the separation\nmechanism relies on steric interactions between polymer segments, which prevent\nsubstrate disorder sites from trapping more than one DNA segment each. Since\nthermal activation does not play a significant role in determining the polymer\nmobility, band broadening due to diffusion can be avoided in our separation\nmethod."
    },
    {
        "anchor": "The Nanocaterpillar's Random Walk: Diffusion With Ligand-Receptor\n  Contacts: Particles with ligand-receptor contacts bind and unbind fluctuating \"legs\" to\nsurfaces, whose fluctuations cause the particle to diffuse. Quantifying the\ndiffusion of such \"nanoscale caterpillars\" is a challenge, since binding events\noften occur on very short time and length scales. Here we derive an analytical\nformula, validated by simulations, for the long time translational diffusion\ncoefficient of an overdamped nanocaterpillar, under a range of modeling\nassumptions. We demonstrate that the effective diffusion coefficient, which\ndepends on the microscopic parameters governing the legs, can be orders of\nmagnitude smaller than the background diffusion coefficient. Furthermore it\nvaries rapidly with temperature, and reproduces the striking variations seen in\nexisting data and our own measurements of the diffusion of DNA-coated colloids.\nOur model gives insight into the mechanism of motion, and allows us to ask:\nwhen does a nanocaterpillar prefer to move by sliding, where one leg is always\nlinked to the surface, and when does it prefer to move by hopping, which\nrequires all legs to unbind simultaneously? We compare a range of systems\n(viruses, molecular motors, white blood cells, protein cargos in the nuclear\npore complex, bacteria such as Escherichia coli, and DNA-coated colloids) and\npresent guidelines to control the mode of motion for materials design.",
        "positive": "Morphoelasticity of Large Bending Deformations of Cell Sheets during\n  Development: Deformations of cell sheets during morphogenesis are driven by developmental\nprocesses such as cell division and cell shape changes. In morphoelastic shell\ntheories of development, these processes appear as variations of the intrinsic\ngeometry of a thin elastic shell. However, morphogenesis often involves large\nbending deformations that are outside the formal range of validity of these\nshell theories. Here, by asymptotic expansion of three-dimensional\nincompressible morphoelasticity in the limit of a thin shell, we derive a shell\ntheory for large intrinsic bending deformations and emphasise the resulting\ngeometric material anisotropy and the elastic role of cell constriction. Taking\nthe invagination of the green alga Volvox as a model developmental event, we\nshow how results for this theory differ from those for a classical shell theory\nthat is not formally valid for these large bending deformations and reveal how\nthese geometric effects stabilise invagination."
    },
    {
        "anchor": "Filling the void in confined polymer nematics: phase transitions in a\n  minimal model of dsDNA packing: Inspired to understand the complex spectrum of space-filling organizations\nthe dsDNA genome within the capsid of bacterial viruses, we study a minimal,\ncoarse-grained model of single chains densely-packed into a finite spherical\nvolume. We build the three basic elements of the model--i) the absence of chain\nends ii) the tendency of parallel-strand alignment and iii) a preference of\nuniform areal density of chain segments--into a polymer nematic theory for\nconfined chains. Given the geometric constraints of the problem, we show that\naxially symmetric packings fall into one of three topologies: the coaxial\nspool; the simple solenoid; and the twisted-solenoid. Among these, only the\ntwisted-solenoid fills the volume without the presence of line-like\ndisclinations, or voids, and are therefore generically preferred in the\nincompressible limit. An analysis of the thermodynamics behavior of this simple\nmodel reveals a rich behavior, a generic sequence of phases from the empty\nstate for small container sizes, to the coaxial spool configuration at\nintermediate sizes, ultimately giving way, via a second-order,\nsymmetry-breaking transition, to the twisted-solenoid structure above a\ncritical sphere size.",
        "positive": "The origin and nature of Boson Peak: the normal mode analysis of\n  disordered granular crystals: Despite extensive theoretical \\cite{GanterPRL1998,\nElliotPRL2001,SchirmacherPRL2007, TanakaNatureM2008, MonacoPNAS2009,\nMarruzzoSCIRP2013} and experimental studies \\cite{ChumakovPRL2011,\nChumakovPRL2014, KayaScience2010,KChenPRL2010, LXuPRL2012, BonnPreprint2014}, a\nlongstanding puzzle in condensed matter physics remains regarding the origin\nand nature of \"Boson peak\" (BP), where the vibrational density of states (DOS)\nin glasses possesses an excess of states compared with the crystalline\ncounterpart. Here we show that BP is successfully observed in 2D hexagonal\ngranular packing, where the disorder is due to the force network, i.e. the\nspatial heterogeneity of elasticity \\cite{MarruzzoSCIRP2013}. Using\nphoto-elastic techniques \\cite{TrushNature2005}, the disordered particle\ninteraction can be precisely measured to resolve the origin and nature of BP\nfor the first time in a real scenario. We discover the structures of DOS of\ndisordered crystals reminiscent of the corresponding perfect crystals, which is\nconsistent with the recent studies in $SiO_2$\\cite{ChumakovPRL2014} and in\ndisordered gels\\cite{LorenzoGelPaper2011}, notwithstanding the drastically\ndifferent systems. Moreover, we propose a mechanism to clarify that BP is not\nmerely a broadened and shifted van Hove singularity \\cite{ElliotPRL2001,\nChumakovPRL2011} but instead it is due to an interplay of the mesoscopic\nscreening effect and the microscopic elasticity disorder -- causing,\nrespectively, the broadening and the attenuation of the first and the second\nvan Hove singularity. This may lead to an in-depth understanding of BP in\nstructure glasses."
    },
    {
        "anchor": "Effect of cold collisions on spin coherence and resonance shifts in a\n  magnetically trapped ultra-cold gas: We have performed precision microwave spectroscopy on ultra-cold Rb-87\nconfined in a magnetic trap, both above and below the Bose-condensation\ntransition. The cold collision shifts for both normal and condensed clouds were\nmeasured, which allowed the intra- and inter-state density correlations\n(characterized by sometimes controversial \"factors of two\") to be determined.\nAdditionally, temporal coherence of the normal cloud was studied, and the\nimportance of mean-field and velocity-changing collisions in preserving\ncoherence is discussed.",
        "positive": "Phase behavior of C18 monoglyceride in hydrophobic solutions: We apply a set of different techniques to analyze the physical properties and\nphase transitions of monoglycerides (MG) in oil. In contrast to many studies of\nMG in water or aqueous systems, we find a significant difference in the phase\nstructure at different concentrations and temperatures. By adding small\nquantities of water to our base MG/oil systems we test the effect of hydration\nof surfactant head-groups, and its effect on the phase behavior. The phase\ndiagrams are determined by calorimetry and their universal features are\nrecorded under different conditions. Two ordered phases are reported: the\ninverse lamellar gel phase and the sub-alpha crystalline gel phase. This\nsequence is very different from the structures in MG/water; its most striking\nfeature is the establishing of a 2D densely packed hexagonal order of glycerol\nheads in the middle of inverse lamellar bilayers. Rheology was examined through\ntemperature scans to demonstrate the gelation phenomenon, which starts from the\nonset of the lamellar phase during the cooling/ordering process."
    },
    {
        "anchor": "Overtwisting induces polygonal shapes in bent DNA: By combining analytical results and simulations of various coarse-grained\nmodels we investigate the minimal energy shape of DNA minicircles which are\ntorsionally constrained by an imposed over or undertwist. We show that\ntwist-bend coupling, a cross interaction term discussed in the recent DNA\nliterature, induces minimal energy shapes with a periodic alternance of parts\nwith high and low curvature resembling rounded polygons. We briefly discuss the\npossible experimental relevance of these findings. We finally show that the\ntwist and bending energies of minicircles are governed by renormalized\nstiffness constants, not the bare ones. This has important consequences for the\nanalysis of experiments involving circular DNA meant to determine DNA elastic\nconstants.",
        "positive": "Ion specificity modulated inhomogeneous interfacial flow inhibits bubble\n  coalescence in electrolyte solutions: Inhibition of bubble coalescence in electrolyte solutions enables the\nformation of oceanic whitecaps and affects the heat and mass transfer in many\nbubble related engineering processes. For different electrolytes, the ability\nto inhibit bubble coalescence correlates to the ion specificity at the air\nwater interface at an abnormal cation-anion pair relationship, rather than the\ntypically expected cation or anion series that was widely reported in\natmospheric, bio- and chemical processes. Here we show that the inhomogeneous\ninterfacial flow, at a different electrolyte concentration from the solution\nbecause of the surface specificity of both cation and anion, contributes to the\nbubble coalescence inhibition behavior in electrolyte solutions. The\ninterfacial flow, achieved with the mobile air-water interface, contributes to\nthe continuous change of electrolyte concentration within the liquid film\nformed between two colliding bubbles, thereby resulting in a concentration\ngradient of electrolytes between the thin film and the bulk solution. The\nelectrolyte concentration gradient, hence surface tension gradient, becomes\nsignificant to resist film thinning when the film thickness reaches tens of\nnanometers. The retarded film thinning between two bubbles and delayed bubble\ncoalescence were experimentally captured by high-speed interferometry and\nquantitatively explained by the proposed electrolyte transportation model. This\nfinding clearly highlights the coupled effect of interfacial flow and ion\nspecificity, and shows important implications for improved understanding of\nocean waves, for future development of colloidal science in high concentration\nelectrolyte solutions that is critical for biology, and benefits many applied\nfields like water splitting and mineral extraction."
    },
    {
        "anchor": "Structural-dynamical transition in the Wahnstr\u00f6m mixture: In trajectory space, dynamical heterogeneities in glass-forming liquids\ncorrespond to the emergence of a dynamical phase transition between an active\nphase poor in local structure and an inactive phase which is rich in local\nstructure. We support this scenario with the study of a model additive mixture\nof Lennard-Jones particles, quantifying how the choice of the relevant\nstructural and dynamical observable affects the transition in trajectory space.\nWe find that the low mobility, structure-rich phase is dominated by icosahedral\norder. Applying a nonequilibrium rheological protocol, we connect local order\nto the emergence of mechanical rigidity.",
        "positive": "Internal Stress in a Model Elasto-Plastic Fluid: Plastic materials can carry memory of past mechanical treatment in the form\nof internal stress. We introduce a natural definition of the vorticity of\ninternal stress in a simple two-dimensional model of elasto-plastic fluids,\nwhich generates the internal stress. We demonstrate how the internal stress is\ninduced under external loading, and how the presence of the internal stress\nmodifies the plastic behavior."
    },
    {
        "anchor": "Isotropic, Nematic and Smectic A Phase Behaviour in a Fictitious Field: Phase behaviours of liquid crystals under external fields, conjugate to the\nnematic order and smectic order, are studied within the framework of mean field\napproximation developed by McMillan. It is found that phase diagrams, of\ntemperature vs interaction parameter of smectic A order, show several\ntopologically different types caused by the external fields. The influences of\nthe field conjugate to the smectic A phase, which is fictitious field, are\nprecisely discussed.",
        "positive": "Contact angle hysteresis at the nanoscale: Understanding the physics of a three-phase contact line between gas, liquid,\nand solid is important for numerous applications. At the macroscale, the\nthree-phase contact line response to an external force action is often\ncharacterized by a contact angle hysteresis, and several models are presented\nin the literature for its description. Yet, there is still a need for more\ninformation about such model applications at the nanoscale. In this study, a\nmolecular dynamics approach was used to investigate the shape of a liquid\ndroplet under an external force for different wetting regimes. In addition, an\nanalytic model for describing the droplet shape was developed. It gives us the\npossibility to evaluate the receding and advancing wetting angle accurately.\nWith our modeling, we found that the interplay between capillary forces and\nviscous forces is crucial to characterize the droplet shape at the nanoscale.\nIn this frame, the importance of the rolling movement of the interface between\nliquid and vapor was pointed out. We also demonstrate that in the range of the\nexternal forces when capillary forces are most significant compared to others,\nhysteresis is well described by the macroscale Cox-Voinov model."
    },
    {
        "anchor": "Extraction of Force-Chain Network Architecture in Granular Materials\n  Using Community Detection: Force chains form heterogeneous physical structures that can constrain the\nmechanical stability and acoustic transmission of granular media. However,\ndespite their relevance for predicting bulk properties of materials, there is\nno agreement on a quantitative description of force chains. Consequently, it is\ndifficult to compare the force-chain structures in different materials or\nexperimental conditions. To address this challenge, we treat granular materials\nas spatially-embedded networks in which the nodes (particles) are connected by\nweighted edges that represent contact forces. We use techniques from community\ndetection, which is a type of clustering, to find sets of closely connected\nparticles. By using a geographical null model that is constrained by the\nparticles' contact network, we extract chain-like structures that are\nreminiscent of force chains. We propose three diagnostics to measure these\nchain-like structures, and we demonstrate the utility of these diagnostics for\nidentifying and characterizing classes of force-chain network architectures in\nvarious materials. To illustrate our methods, we describe how force-chain\narchitecture depends on pressure for two very different types of packings: (1)\nones derived from laboratory experiments and (2) ones derived from idealized,\nnumerically-generated frictionless packings. By resolving individual force\nchains, we quantify statistical properties of force-chain shape and strength,\nwhich are potentially crucial diagnostics of bulk properties (including\nmaterial stability). These methods facilitate quantitative comparisons between\ndifferent particulate systems, regardless of whether they are measured\nexperimentally or numerically.",
        "positive": "Surface wave excitations and backflow effect over dense polymer brushes: Polymer brushes are increasingly used to tailor surface physicochemistry for\nvarious applications such as wetting, adhesion of biological objects,\nimplantable devices, etc. We perform Dissipative Particle Dynamics simulations\nto study the behavior of dense polymer brushes under flow in a slit-pore\nchannel. We discover that the system displays flow inversion at the brush\ninterface for several disconnected ranges of the imposed flow. We associate\nsuch phenomenon to collective polymer dynamics: a wave propagating on the brush\nsurface. The relation between the wavelength, the amplitude and the propagation\nspeed of the flow-generated wave is consistent with the solution of the Stokes\nequations when an imposed traveling wave is assumed as boundary condition (the\nfamous Taylor's swimmer)."
    },
    {
        "anchor": "Influence of hydrodynamic interactions on lane formation in oppositely\n  charged driven colloids: The influence of hydrodynamic interactions on lane formation of oppositely\ncharged driven colloidal suspensions is investigated using Brownian dynamics\ncomputer simulations performed on the Rotne-Prager level of the mobility\ntensor. Two cases are considered, namely sedimentation and electrophoresis. In\nthe latter case the Oseen contribution to the mobility tensor is screened due\nto the opposite motion of counterions. The simulation results are compared to\nthat resulting from simple Brownian dynamics where hydrodynamic interactions\nare neglected. For sedimentation, we find that hydrodynamic interactions\nstrongly disfavor laning. In the steady-state of lanes, a macroscopic phase\nseparation of lanes is observed. This is in marked contrast to the simple\nBrownian case where a finite size of lanes was obtained in the steady-state.\nFor strong Coulomb interactions between the colloidal particles a lateral\nsquare lattice of oppositely driven lanes is stable similar to the simple\nBrownian dynamics. In an electric field, on the other hand, the behavior is\nfound in qualitative and quantitative accordance with the case of neglected\nhydrodynamics.",
        "positive": "Crackling dynamics in the mechanical response of knitted fabrics,\n  Version 2: Crackling noise, which occurs in a wide range of situations, is characterized\nby discrete events of various sizes, often correlated in the form of\navalanches. We report experimental evidence that the mechanical response of\nknitted fabric displays such broadly distributed events both in the force\nsignal and in the deformation field, with statistics analogous to that of\nearthquakes or soft amorphous materials. A knit consists of a regular network\nof frictional contacts, linked by the elasticity of the yarn. When deformed,\nthe fabric displays spatially extended avalanche-like yielding events resulting\nfrom collective inter-yarn contact slips. We measure the size distribution of\nthese avalanches, at the stitch level from the analysis of non-elastic\ndisplacement fields, and externally from force fluctuations. The two\nmeasurements yield consistent power law distributions reminiscent of those\nfound in other avalanching systems. Our study shows that a knitted fabric is\nnot only a thread-based metamaterial with highly sought after mechanical\nproperties, but also an original, model system, with topologically protected\nstructural order, where intermittent, scale-invariant response emerges from\nminimal ingredients, and thus a significant landmark in the study of\nout-of-equilibrium universality."
    },
    {
        "anchor": "Shear Induced Fluidization Of Thermal Amorphous Solids: We study the shear induced fluidization of amorphous solids subjected to\nexternal loading by investigating the relaxation dynamics of the deformed\nstates using computer simulation. A simple shear deformation is employed at\nconstant rate to the thermal glassy materials. The shear localization and the\nplastic deformation heterogeneity with strain is investigated in terms of the\nnon-affine displacement field. The mean square displacement shows an enhanced\nmobility of the particles with strain, indicating the fluidization of the\nmaterial. Using the time correlation function we estimate the relaxation time\nof the sheared glasses. A significant decrease in the relaxation time is\nobserved up to the yielding point as the material loses its solid nature and\neventually becomes liquid-like. Finally, the imprint of memory of the quiescent\nsample on the rheological properties of the shear melted glass is investigated\nby computing the relaxation of the shear stress. We find a finite persistent\nresidual stress that outlasts the experimental observation time in our system.",
        "positive": "Low frequency spectra of bending wave turbulence: We study experimentally the dynamics of long waves among turbulent bending\nwaves in a thin elastic plate set into vibration by a monochromatic forcing at\na frequency $f_0$. This frequency is chosen large compared with the\ncharacteristic frequencies of bending waves. As a consequence, a range of\nconservative scales, without energy flux in average, exists for frequencies\n$f<f_0$. Within this range, we report a flat power density spectrum for the\northogonal velocity, corresponding to energy equipartition between modes. Thus,\nthe average energy per mode $\\beta^{-1}$ -- analogous to a temperature -- fully\ncharacterizes the large-scale turbulent wave field. We present an expression\nfor $\\beta$ as a function of the forcing frequency and amplitude, and of the\nplate characteristics."
    },
    {
        "anchor": "Phase Behavior of Aqueous Suspension of Laponite: New Insights with\n  Microscopic Evidence: Investigating microstructure of suspensions with particles having anisotropic\nshape that share complex interactions is a challenging task leading to\ncompeting claims. This work investigates phase behavior of one such system:\naqueous Laponite suspension, which is highly contested in the literature, using\nrheological and microscopic tools. Remarkably, we observe that over a broad\nrange of Laponite (1.4 to 4 weight %) and salt concentrations (0 to 7 mM), the\nsystem overwhelmingly demonstrates all the rheological characteristics of the\nsol-gel transition leading to a percolated network. Analysis of the rheological\nresponse leads to fractal dimension that primarily depends on the Laponite\nconcentration. We also obtain the activation energy for gelation, which is\nobserved to decrease with increase in Laponite as well as salt concentration.\nSignificantly, the cryo-TEM images of the post-gel state clearly show presence\nof a percolated network formed by inter-particle bonds. The present work\ntherefore conclusively establishes the system to be in an attractive gel state\nresolving a long-standing debate in the literature.",
        "positive": "Novel critical phenomena in compressible polar active fluids: Dynamical\n  and Functional Renormalization Group Studies: Active matter is not only relevant to living matter and diverse\nnonequilibrium systems, but also constitutes a fertile ground for novel\nphysics. Indeed, dynamic renormalization group (DRG) analyses have uncovered\nmany new universality classes (UCs) in polar active fluids (PAFs) - an\narchetype of active matter systems. However, due to the inherent technical\ndifficulties in the DRG methodology, almost all previous studies have been\nrestricted to polar active fluids in the incompressible or infinitely\ncompressible (i.e., Malthusian) limits, and, when the $\\epsilon$-expansion was\nused in conjunction, to the one-loop level. Here, we use functional\nrenormalization group (FRG) methods to bypass some of these difficulties and\nunveil for the first time novel critical behavior in compressible polar active\nfluids, and calculate the corresponding critical exponents beyond the one-loop\nlevel. Specifically, we investigate the multicritical point of compressible\nPAFs, where the critical order-disorder transition coincides with critical\nphase separation. We first study the critical phenomenon using a DRG analysis\nand find that it is insufficient since two-loop effects are important to obtain\na nontrivial correction to the scaling exponents. We then remedy this defect by\nusing a FRG analysis. We find three novel universality classes and obtain their\ncritical exponents, which we then use to show that at least two of these\nuniversality classes are out of equilibrium because they violate the\nfluctuation-dissipation relation."
    },
    {
        "anchor": "Localization Transition of the Three-Dimensional Lorentz Model and\n  Continuum Percolation: The localization transition and the critical properties of the Lorentz model\nin three dimensions are investigated by computer simulations. We give a\ncoherent and quantitative explanation of the dynamics in terms of continuum\npercolation theory, an excellent matching of both the critical density and\nexponents is obtained. Upon exploiting a dynamic scaling Ansatz employing two\ndivergent length scales we find data collapse for the mean-square displacements\nand identify the leading-order corrections to scaling. The non-Gaussian\nparameter is predicted to diverge at the transition.",
        "positive": "Microphase separation in two dimensional suspensions of self-propelled\n  spheres and dumbbells: We use numerical simulations to study the phase behavior of self-propelled\nspherical and dumbbellar particles interacting via micro-phase separation\ninducing potentials. Our results indicate that under the appropriate\nconditions, it is possible to drive the formation of two new active states; a\nspinning cluster crystal, i.e. an ordered mesoscopic phase having finite size\nspinning crystallites as lattice sites, and a fluid of living clusters, i.e. a\ntwo dimensional fluid where each \"particle\" is a finite size living cluster. We\ndiscuss the dynamics of these phases and suggest ways of extending their\nstability under a wide range of active forces."
    },
    {
        "anchor": "An atomistically informed multiscale approach to the intrusion and\n  extrusion of water in hydrophobic nanopores: Understanding intrusion and extrusion in nanoporous materials is a\nchallenging multiscale problem of utmost importance for applications ranging\nfrom energy storage and dissipation to water desalination and hydrophobic\ngating in ion channels. Including atomistic details in simulations is required\nto predict the overall behavior of such systems, because the statics and\ndynamics of these processes depend sensitively on microscopic features of the\npore such as the surface hydrophobicity, geometry, and charge distribution and\non the composition of the liquid. On the other hand, the transitions between\nthe filled (intruded) and empty (extruded) states are rare events which often\nrequire long simulation times difficult to achieve with standard atomistic\nsimulations. In this work, we explored the intrusion and extrusion processes by\na multiscale approach in which the atomistic details of the system, extracted\nfrom molecular dynamics simulations, inform a simple Langevin model of water\nintrusion/extrusion in the pore. We then used the Langevin simulations to\ncompute the transition times at different pressures, validating our\ncoarse-grained model by comparing it with nonequilibrium molecular dynamics\nsimulations. The proposed approach reproduces experimentally relevant features\nsuch as the time and temperature dependence of the intrusion/extrusion cycles,\nas well as specific details about the shape of the cycle. This approach also\ndrastically increases the timescales that can be simulated allowing to reduce\nthe gap between simulations and experiments and showing promise for more\ncomplex systems.",
        "positive": "Wetting and particle adsorption in nanoflows: Molecular dynamics simulations are used to study the behavior of\nclosely-fitting spherical and ellipsoidal particles moving through a\nfluid-filled cylinder at nanometer scales. The particle, the cylinder wall and\nthe fluid solvent are all treated as atomic systems, and special attention is\ngiven to the effects of varying the wetting properties of the fluid. Although\nthe modification of the solid-fluid interaction leads to significant changes in\nthe microstructure of the fluid, its transport properties are found to be the\nsame as in bulk. Independently of the shape and relative size of the particle,\nwe find two distinct regimes as a function of the degree of wetting, with a\nsharp transition between them. In the case of a highly-wetting suspending\nfluid, the particle moves through the cylinder with an average axial velocity\nin agreement with that obtained from the solution of the continuum Stokes\nequations. In contrast, in the case of less-wetting fluids, only the early-time\nmotion of the particle is consistent with continuum dynamics. At later times,\nthe particle is eventually adsorbed onto the wall and subsequently executes an\nintermittent stick-slip motion.We show that van der Walls forces are the\ndominant contribution to the particle adsorption phenomenon and that depletion\nforces are weak enough to allow, in the highly-wetting situation, an initially\nadsorbed particle to spontaneously desorb."
    },
    {
        "anchor": "Entropy-driven aggregation in multilamellar membranes: Membrane-fluctuation-induced attraction between ligand--receptor sites\nbinding neighboring membranes is studied using meshless membrane simulations\nand the Weil--Farago two-dimensional lattice model. For the adhesion sites\nbinding two membranes, this entropic interaction is too weak by itself for the\nadhesion sites to form a large stable domain. However, it is found that this\nattraction is enhanced sufficiently to induce large domains either when the\nsites bind three or more neighboring membranes together or have anchors that\nharden surrounding membranes. The latter effect is understood by the\nAsakura--Oosawa type of effective potential in the depletion theory.",
        "positive": "Diffusiophoresis driven colloidal manipulation and shortcuts to\n  adiabaticity: While compressing a colloidal state by optical means alone has been\npreviously achieved through a specific time-dependence of the trap stiffness,\nrealizing quickly the reverse transformation stumbles upon the necessity of a\ntransiently expulsive trap. To circumvent this difficulty, we propose to drive\nthe colloids by a combination of optical trapping and diffusiophoretic forces,\nboth time-dependent. Forcing via diffusiophoresis is enforced by controlling\nthe salt concentration at the boundary of the domain where the colloids are\nconfined. The method takes advantage of the separation of time scales between\nsalt and colloidal dynamics, and realizes a fast decompression in an optical\ntrap that remains confining at all times. We thereby obtain a so-called\nshortcut to adiabaticity protocol where colloidal dynamics, enslaved to salt\ndynamics, can nevertheless be controlled as desired."
    },
    {
        "anchor": "Removing grain boundaries from three-dimensional colloidal crystals\n  using active dopants: Using computer simulations we explore how grain boundaries can be removed\nfrom three-dimensional colloidal crystals by doping with a small fraction of\nactive colloids. We show that for sufficient self-propulsion, the system is\ndriven into a crystal-fluid coexistence. In this phase separated regime, the\nactive dopants become mobile and spontaneously gather at the grain boundaries.\nThe resulting surface melting and recrystallization of domains result in the\nmotion of the grain boundaries over time and lead to the formation of a large\nsingle crystal. However, when the self-propulsion is too low to cause a phase\nseparation, we observe no significant enhancement of grain growth.",
        "positive": "Dichotomic Aging Behaviour in a Colloidal Glass: An unexpected dichotomic long time aging behaviour is observed in a glassy\ncolloidal clay suspension investigated by X-Ray Photon Correlation Spectroscopy\nand Dynamic Light Scattering. In the long time aging regime the intensity\nautocorrelations are non-exponential, following the Kohlrausch-Williams-Watts\nfunctional form with exponent bQ. We show that for spontaneously aged samples a\nstretched behaviour (\\beta_Q < 1) is always found. Surprisingly a compressed\nexponent (\\beta_Q > 1) appears only when the system is rejuvenated by\napplication of a shear field. In both cases the relaxation times scale as\nQ^{-1}. These observations shed light on the origin of compressed exponential\nbehaviour and helps in classifying previous results in the literature on\nanomalous dynamics."
    },
    {
        "anchor": "Motility and Swimming: Universal Description and Generic Trajectories: Autonomous locomotion is a ubiquitous phenomenon in biology and in physics of\nactive systems at microscopic scale. This includes prokaryotic, eukaryotic\ncells (crawling and swimming) and artificial swimmers. An outstanding feature\nis the ability of these entities to follow complex trajectories, ranging from\nstraight, curved (circular, helical...), to random-like ones. The non-straight\nnature of these trajectories is often explained as a consequence of the\nasymmetry of the particle or the medium in which it moves, or due to the\npresence of bounding walls, etc... Here, we show that straight, circular and\nhelical trajectories emerge naturally in the absence of asymmetry of the\nswimmer or that of suspending medium. Our first proof is based on general\nconsiderations, without referring to an explicit form of a model. We show that\nthese three trajectories correspond to self-congruent solutions.\nSelf-congruency means that the states of the system at different moments of\ntime can be made identical by an appropriate combination of rotation and\ntranslation of the coordinate space. We show that these solutions are exhibited\nby spherically symmetric particles as a result of a series of pitchfork\nbifurcations as the activity is increased. Self-congruent dynamics in one and\ntwo dimensions are analyzed as well. Finally, we present a simple explicit\nnonlinear exactly solvable model of fully isotropic phoretic particle that\nshows the transitions from a non-motile state to straight motion to circular\nmotion to helical motion as a series of spontaneous symmetry-breaking\nbifurcations. Whether a system exhibits or not a given trajectory only depends\non the numerical values of parameters entering the model, while asymmetry of\nswimmer shape, or anisotropy of the suspending medium , or influence of\nbounding walls are not necessary.",
        "positive": "Influences of microcontact shape on the state of a frictional interface: The real area of contact of a frictional interface changes rapidly when the\nnormal load is altered, and evolves slowly when normal load is held constant,\naging over time. Traditionally, the total area of contact is considered a proxy\nfor the frictional strength of the interface. Here we show that the state of a\nfrictional interface is not entirely defined by the total real area of contact\nbut depends on the geometrical nature of that contact as well. We directly\nvisualize an interface between rough elastomers and smooth glass and identify\nthat normal loading and frictional aging evolve the interface differently, even\nat a single contact level. We introduce a protocol wherein the real area of\ncontact is held constant in time. Under these conditions, the interface is\ncontinually evolving; small contacts shrink and large contacts coarsen."
    },
    {
        "anchor": "Why do ultrasoft repulsive particles cluster and crystallize? Analytical\n  results from density functional theory: We demonstrate the accuracy of the hypernetted chain closure and of the\nmean-field approximation for the calculation of the fluid-state properties of\nsystems interacting by means of bounded and positive-definite pair potentials\nwith oscillating Fourier transforms. Subsequently, we prove the validity of a\nbilinear, random-phase density functional for arbitrary inhomogeneous phases of\nthe same systems. On the basis of this functional, we calculate analytically\nthe freezing parameters of the latter. We demonstrate explicitly that the\nstable crystals feature a lattice constant that is independent of density and\nwhose value is dictated by the position of the negative minimum of the Fourier\ntransform of the pair potential. This property is equivalent with the existence\nof clusters, whose population scales proportionally to the density. We\nestablish that regardless of the form of the interaction potential and of the\nlocation on the freezing line, all cluster crystals have a universal Lindemann\nratio L = 0.189 at freezing. We further make an explicit link between the\naforementioned density functional and the harmonic theory of crystals. This\nallows us to establish an equivalence between the emergence of clusters and the\nexistence of negative Fourier components of the interaction potential. Finally,\nwe make a connection between the class of models at hand and the system of\ninfinite-dimensional hard spheres, when the limits of interaction steepness and\nspace dimension are both taken to infinity in a particularly described fashion.",
        "positive": "Simulating rare events in equilibrium or non-equilibrium stochastic\n  systems: We present three algorithms for calculating rate constants and sampling\ntransition paths for rare events in simulations with stochastic dynamics. The\nmethods do not require a priori knowledge of the phase space density and are\nsuitable for equilibrium or non-equilibrium systems in stationary state. All\nthe methods use a series of interfaces in phase space, between the initial and\nfinal states, to generate transition paths as chains of connected partial\npaths, in a ratchet-like manner. No assumptions are made about the distribution\nof paths at the interfaces. The three methods differ in the way that the\ntransition path ensemble is generated. We apply the algorithms to kinetic Monte\nCarlo simulations of a genetic switch and to Langevin Dynamics simulations of\nintermittently driven polymer translocation through a pore. We find that the\nthree methods are all of comparable efficiency, and that all the methods are\nmuch more efficient than brute force simulation."
    },
    {
        "anchor": "Surface-charge-induced freezing of colloidal suspensions: Using grand-canonical Monte Carlo simulations we investigate the impact of\ncharged walls on the crystallization properties of charged colloidal\nsuspensions confined between these walls. The investigations are based on an\neffective model focussing on the colloids alone. Our results demonstrate that\nthe fluid-wall interaction stemming from charged walls has a crucial impact on\nthe fluid's high-density behavior as compared to the case of uncharged walls.\nIn particular, based on an analysis of in-plane bond order parameters we find\nsurface-charge-induced freezing and melting transitions.",
        "positive": "Structure and thermodynamics of colloid-polymer mixtures: a\n  macromolecular approach: The change of the structure of concentrated colloidal suspensions upon\naddition of non-adsorbing polymer is studied within a two-component,\nOrnstein-Zernicke based liquid state approach. The polymers' conformational\ndegrees of freedom are considered and excluded volume is enforced at the\nsegment level. The polymer correlation hole, depletion layer, and excess\nchemical potentials are described in agreement with polymer physics theory in\ncontrast to models treating the macromolecules as effective spheres. Known\ndepletion attraction effects are recovered for low particle density, while at\nhigher densities novel many-body effects emerge which become dominant for large\npolymers."
    },
    {
        "anchor": "Quasi-crystalline order in vibrated granular matter: Quasi-crystals are aperiodic structures that present crystallographic\nproperties which are not compatible with that of a single unit cell. Their\nrevolutionary discovery in a metallic alloy, less than three decades ago, has\nrequired a full reconsideration of what we defined as a crystal structure.\nSurprisingly, quasi-crystalline structures have been discovered also at much\nlarger length scales in different microscopic systems for which the size of\nelementary building blocks ranges between the nanometric to the micrometric\nscale. Here, we report the first experimental observation of spontaneous\nquasi-crystal self-assembly at the millimetric scale. This result is obtained\nin a fully athermal system of macroscopic spherical grains vibrated on a\nsubstrate. Starting from a liquid-like disordered phase, the grains begin to\nlocally arrange into three types of squared and triangular tiles that\neventually align, forming 8-fold symmetric quasi-crystal that has been\npredicted in simulation but not yet observed experimentally in non-atomic\nsystems. These results are not only the proof of a novel route to spontaneously\nassemble quasi-crystals but are of fundamental interest for the connection\nbetween equilibrium and non-equilibrium statistical physics.",
        "positive": "Squeezing multiple soft particles into a constriction: transition to\n  clogging: We study numerically how multiple deformable capsules squeeze into a\nconstriction. This situation is largely encountered in microfluidic chips\ndesigned to manipulate living cells, which are soft entities. We use fully\nthree-dimensional simulations based on the lattice Boltzmann method to compute\nthe flow of the suspending fluid, and on the immersed boundary method to\nachieve the two-way fluid-structure interaction. The mechanics of the capsule\nmembrane elasticity is computed with the finite element method. We obtain two\nmain states: continuous passage of the particles, and their blockage that leads\nto clogging the constriction. The transition from one state to another is\ndictated by the ratio between the size of the capsules and the constriction\nwidth, and by the capsule membrane deformability. This latter is found to\nenhance particle passage through narrower constrictions, where rigid particles\nwith similar diameter are blocked and lead to clogging."
    },
    {
        "anchor": "Accelerated Atomistic Simulations of a Supramolecular Polymer in Water: All-atom molecular dynamics has been recently proven a useful tool for the\nstudy of supramolecular polymers. While the high resolution offered by the\natomistic models may allow for deep comprehension of the assembled structure,\nobtaining a reliable equilibrated configuration for these soft assemblies in\naqueous solution remains a challenging task mainly due to the complexity of the\natomistic systems and the long simulation time needed for their equilibration.\nHere we have tested two well-known advanced simulation methods (Accelerated\nMolecular Dynamics and Metadynamics) on an atomistic model of water-soluble\n1,3,5-benzenetricarboxamide (BTA) supramolecular polymer and have compared the\nobtained data to classical molecular dynamics. Our results show that both\ntechniques can be very useful to accelerate the equilibration of the\nsupramolecular fiber in solution. Moreover, we demonstrate that combining the\ntwo methods in opportune way allows to take advantage of the strong points of\nboth, providing an equilibrated configuration for the BTA supramolecular\npolymer in a faster and more reproducible way compared to classical\nsimulations. The versatility of this approach suggests that the latter can be\nadapted to simulate a variety of supramolecular polymers as well as different\ntypes of supramolecular assemblies.",
        "positive": "Diffusion and velocity correlations of the phase transitions in a system\n  of macroscopic rolling spheres: We study an air-fluidized granular monolayer, composed of plastic spheres\n  which roll on a metallic grid. The air current is adjusted so that the\nspheres never loose contact\n  with the grid, so that the dynamics may be regarded as pseudo two-dimensional\n(or two-dimensional,\n  if the effects of sphere rolling are not taken into account). We find two\nsurprising continuous\n  transitions, both of them displaying two coexisting phases. Moreover, in all\ncases, we found the\n  coexisting phases display strong energy non-equipartition. In the first\ntransition, at weak\n  fludization, a glassy phase coexists with a disordered fluid-like phase. In\nthe second transition,\n  a hexagonal crystal coexists with the fluid phase. We analyze, for these\ntwo-phase systems, the\n  specific diffusive properties of each phase, as well as the velocity\ncorrelations. Surprisingly,\n  we find a glass phase at very low packing fraction and for a wide range of\ngranular\n  temperatures. Both phases are characterized also by a strong anti-correlated\nvelocities upon\n  collision. Thus, the dynamics observed for this quasi two-dimensional system\nunveils phase\n  transitions with peculiar properties, very different from the predicted\nbehavior in well know\n  theories for their equilibrium counterparts."
    },
    {
        "anchor": "Onsager reciprocity in premelting solids: The diffusive motion of colloidal particles dispersed in a premelting solid\nis analyzed within the framework of irreversible thermodynamics. We determine\nthe mass diffusion coefficient, thermal diffusion coefficient and Soret\ncoefficient of the particles in the dilute limit, and find good agreement with\nexperimental data. In contrast to liquid suspensions, the unique nature of\npremelting solids allows us to derive an expression for the Dufour coefficient\nand independently verify the Onsager reciprocal relation coupling diffusion to\nthe flow of heat.",
        "positive": "Surface Crystallization in a Liquid AuSi Alloy: X-ray measurements reveal a crystalline monolayer at the surface of the\neutectic liquid Au_{82}Si_{18}, at temperatures above the alloy's melting\npoint. Surface-induced atomic layering, the hallmark of liquid metals, is also\nfound below the crystalline monolayer. The layering depth, however, is\nthreefold greater than that of all liquid metals studied to date. The\ncrystallinity of the surface monolayer is notable, considering that AuSi does\nnot form stable bulk crystalline phases at any concentration and temperature\nand that no crystalline surface phase has been detected thus far in any pure\nliquid metal or nondilute alloy. These results are discussed in relation to\nrecently suggested models of amorphous alloys."
    },
    {
        "anchor": "Two-stage Seebeck effect in charged colloidal suspensions: We discuss the peculiarities of the Seebeck effect in stabilized electrolytes\ncontaining the colloidal particles. Its unusual feature is the two-stage\ncharacter, with the linear increase of differential thermopower as the function\nof colloidal particles concentration $n_{\\odot}$ during the first stage and\ndramatic drop of it at small $n_{\\odot}$ during the second one (steady state).\nWe show that the properties of the initial state are governed by the\nthermo-diffusion flows of the mobile ions of the stabilizing electrolyte medium\nitself and how the colloidal particles participate in formation of the electric\nfield in the bulk of suspension. In its turn the specifics of the steady state\nin thermoelectric effect we attribute to considerable displacements of the\nmassive colloidal particles in process of their slow thermal diffusion and\nbreak down of their electroneutrality in the vicinity of electrodes",
        "positive": "Convection in nanofluids with a particle-concentration-dependent thermal\n  conductivity: Thermal convection in nanofluids is investigated by means of a continuum\nmodel for binary-fluid mixtures, with a thermal conductivity depending on the\nlocal concentration of colloidal particles. The applied temperature difference\nbetween the upper and the lower boundary leads via the Soret effect to a\nvariation of the colloid concentration and therefore to a spatially varying\nheat conductivity. An increasing difference between the heat conductivity of\nthe mixture near the colder and the warmer boundary results in a shift of the\nonset of convection to higher values of the Rayleigh number for positive values\nof the separation ratio psi>0 and to smaller values in the range psi<0. Beyond\nsome critical difference of the thermal conductivity between the two\nboundaries, we find an oscillatory onset of convection not only for psi<0, but\nalso within a finite range of psi>0. This range can be extended by increasing\nthe difference in the thermal conductivity and it is bounded by two\ncodimension-2 bifurcations."
    },
    {
        "anchor": "Effect of Fluctuations on the Freezing of a Colloidal Suspension in an\n  External Periodic Potential: We incorporate the effects of fluctuations in a density functional analysis\nof the freezing of a colloidal liquid in the presence of an external potential\ngenerated by interfering laser beams. A mean field treatment, using a density\nfunctional theory, predicts that with the increase in the strength of the\nmodulating potential, the freezing transition changes from a first order to a\ncontinuous one via a tricritical point for a suitable choice of the modulating\nwavevectors. We demonstrate here that the continuous nature of the freezing\ntransition at large values of the external potential $V_{e}$ survives the\npresence of fluctuations. We also show that fluctuations tend to stabilize the\nliquid phase in the large $V_{e}$ regime.",
        "positive": "On the Physics of Size Selectivity: We demonstrate that two mechanisms used by biological ion channels to select\nparticles by size are driven by entropy. With uncharged particles in an\ninfinite cylinder, we show that a channel that attracts particles is\nsmall-particle selective and that a channel that repels water from the wall is\nlarge-particle selective. Comparing against extensive density-functional theory\ncalculations of our model, we find that the main physics can be understood with\nsurprisingly simple bulk models that neglect the confining geometry of the\nchannel completely."
    },
    {
        "anchor": "History-dependent growth and reduction of the ripples formed on a swept\n  granular track: When a solid object or wheel is repeatedly dragged on a dry sandy surface,\nripple patterns are formed. Although the conditions to form ripple patterns\nhave been studied well, methods to eliminate the developed ripple patterns have\nnot been understood thus far. Therefore, history-dependent stability of the\nripple patterns formed on a sandy surface is investigated in this study. First,\nthe ripple patterns are formed by sweeping the flat sandy surface with a\nflexible plow at a constant speed. Then, the sweeping speed is reduced, and the\nvariation of ripple patterns is measured. As a result, we find that the ripple\npatterns show hysteresis. Specifically, the increase in amplitude of ripples is\nobserved when the reduced velocity is close to the initial velocity forming the\nripple pattern. In addition, splitting of ripples is found when the reduced\nvelocity is further decreased. From a simple analysis of the plow's motion, we\ndiscuss the physical mechanism of the ripple splitting.",
        "positive": "Thermodynamic Scaling of the Viscosity of Van Der Waals, H-Bonded, and\n  Ionic Liquids: Viscosities and their temperature, T, and volume, V, dependences are reported\nfor 7 molecular liquids and polymers. In combination with literature viscosity\ndata for 5 other liquids, we show that the superpositioning of relaxation times\nfor various glass-forming materials when expressed as a function of TV^g, where\nthe exponent g is a material constant, can be extended to the viscosity. The\nlatter is usually measured to higher temperatures than the corresponding\nrelaxation times, demonstrating the validity of the thermodynamic scaling\nthroughout the supercooled and higher T regimes. The value of g for a given\nliquid principally reflects the magnitude of the intermolecular forces (e.g.,\nsteepness of the repulsive potential); thus, we find decreasing g in going from\nvan der Waals fluids to ionic liquids. For strongly H-bonded materials, such as\nlow molecular weight polypropylene glycol and water, the superpositioning\nfails, due to the non-trivial change of chemical structure (degree of\nH-bonding) with thermodynamic conditions."
    },
    {
        "anchor": "Exploring Nanofibrous Networks with X-ray Photon Correlation\n  Spectroscopy: Nanofibrous networks are the foundation and natural building strategy for all\nlife forms on our planet. Apart from providing structural integrity to cells\nand tissues, they also provide a porous scaffold allowing transport of\nsubstances, where the resulting properties rely on the nanoscale network\nstructure. Recently, there has been a great deal of interest in extracting and\nreassembling biobased nanofibers to create sustainable, advanced materials with\napplications ranging from high-performance textiles to artificial tissues.\nHowever, achieving structural control of the extracted nanofibers is\nchallenging as it is strongly dependent on the extraction methods and source\nmaterials. Furthermore, the small nanofiber cross-sections and fast Brownian\ndynamics make them notoriously difficult to characterize in dispersions. In\nthis work, we study the diffusive motion of spherical gold nanoparticles in\nsemi-dilute networks of cellulose nanofibers (CNFs) using X-ray Photon\nCorrelation Spectroscopy (XPCS). We find that the motion becomes increasingly\nsubdiffusive with higher CNF concentration, where the dynamics can be\ndecomposed into several superdiffusive relaxation modes in reciprocal space.\nUsing simulations of confined Brownian dynamics in combination with simulated\nXPCS-experiments, we observe that the dynamic modes can be connected to pore\nsizes and inter-pore transport properties in the network. The demonstrated\nanalytical strategy by combining experiments using tracer particles with a\ndigital twin may be the key to understand nanoscale properties of nanofibrous\nnetworks.",
        "positive": "Tuned, driven, and active soft matter: One characteristic feature of soft matter systems is their strong response to\nexternal stimuli. As a consequence they are comparatively easily driven out of\ntheir ground state and out of equilibrium, which leads to many of their\nfascinating properties. Here, we review illustrative examples. This review is\nstructured by an increasing distance from the equilibrium ground state. On each\nlevel, examples of increasing degree of complexity are considered. In detail,\nwe first consider systems that are quasi-statically tuned or switched to a new\nstate by applying external fields. These are common liquid crystals, liquid\ncrystalline elastomers, or ferrogels and magnetic elastomers. Next, we\nconcentrate on systems steadily driven from outside e.g. by an imposed flow\nfield. In our case, we review the reaction of nematic liquid crystals, of\nbulk-filling periodically modulated structures such as block copolymers, and of\nlocalized vesicular objects to an imposed shear flow. Finally, we focus on\nsystems that are \"active\" and \"self-driven\". Here our range spans from\nidealized self-propelled point particles, via sterically interacting particles\nlike granular hoppers, via microswimmers such as self-phoretically driven\nartificial Janus particles or biological microorganisms, via deformable\nself-propelled particles like droplets, up to the collective behavior of\ninsects, fish, and birds. As we emphasize, similarities emerge in the features\nand behavior of systems that at first glance may not necessarily appear\nrelated. We thus hope that our overview will further stimulate the search for\nbasic unifying principles underlying the physics of these soft materials out of\ntheir equilibrium ground state."
    },
    {
        "anchor": "Slow nucleic acid unzipping kinetics from sequence-defined barriers: Recent experiments on unzipping of RNA helix-loop structures by force have\nshown that about 40-base molecules can undergo kinetic transitions between two\nwell-defined `open' and `closed' states, on a timescale = 1 sec [Liphardt et\nal., Science 297, 733-737 (2001)]. Using a simple dynamical model, we show that\nthese phenomena result from the slow kinetics of crossing large free energy\nbarriers which separate the open and closed conformations. The dependence of\nbarriers on sequence along the helix, and on the size of the loop(s) is\nanalyzed. Some DNAs and RNAs sequences that could show dynamics on different\ntime scales, or three(or more)-state unzipping, are proposed.",
        "positive": "Single-Molecule Structure and Topology of Kinetoplast DNA Networks: The Kinetoplast DNA (kDNA) is a two-dimensional Olympic-ring-like network of\nmutually linked 2.5 kb-long DNA minicircles found in certain parasites called\nTrypanosomes. Understanding the self-assembly and replication of this structure\nare not only major open questions in biology but can also inform the design of\nsynthetic topological materials. Here we report the first high-resolution,\nsingle-molecule study of kDNA network topology using AFM and steered molecular\ndynamics simulations. We map out the DNA density within the network and the\ndistribution of linking number and valence of the minicircles. We also\ncharacterise the DNA hubs that surround the network and show that they cause a\nbuckling transition akin to that of a 2D elastic thermal sheet in the bulk.\nIntriguingly, we observe a broad distribution of density and valence of the\nminicircles, indicating heterogeneous network structure and individualism of\ndifferent kDNA structures. Our findings explain outstanding questions in the\nfield and offer single-molecule insights into the properties of a unique\ntopological material."
    },
    {
        "anchor": "Pressure-induced Shape-shifting of Helical Bacteria: Many bacterial species are helical in form, including the widespread pathogen\nH. pylori. Motivated by recent experiments on H. pylori showing that cell wall\nsynthesis is not uniform, we investigate the possible formation of helical cell\nshape induced by elastic heterogeneity. We show, experimentally and\ntheoretically, that helical morphogenesis can be produced by pressurizing an\nelastic cylindrical vessel with helical reinforced lines. The properties of the\npressurized helix are highly dependent on the initial helical angle of the\nreinforced region. We find that steep angles result in crooked helices with,\nsurprisingly, reduced end-to-end distance upon pressurization. This work helps\nto explain the possible mechanisms for the generation of helical cell\nmorphologies and may inspire the design of novel pressure-controlled helical\nactuators.",
        "positive": "Simulation Study of the Effects of Polymer Network Dynamics and Mesh\n  Confinement on the Diffusion and Structural Relaxation of Penetrants: The diffusion of small molecular penetrants through polymeric materials\nrepresents an important fundamental problem, relevant to the design of\nmaterials for applications such as coatings and membranes. Polymer networks\nhold promise in these applications, because dramatic differences in molecular\ndiffusion can result from subtle changes in the network structure. In this\npaper, we use molecular simulation to understand the role that crosslinked\nnetwork polymers have in governing the molecular motion of penetrants. By\nconsidering the local, activated alpha relaxation time of the penetrant and its\nlong-time diffusive dynamics, we can determine the relative importance of\nactivated glassy dynamics on penetrants at the segmental scale versus entropic\nmesh confinement on penetrant diffusion. We vary several parameters, such as\nthe crosslinking density, temperature, and penetrant size, to show that\ncrosslinks primarily affect molecular diffusion through modification of the\nmatrix glass transition, with local penetrant hopping at least partially\ncoupled to the segmental relaxation of the polymer network. This coupling is\nvery sensitive to the local activated segmental dynamics of the surrounding\nmatrix, and we also show that penetrant transport is affected by dynamic\nheterogeneity at low temperatures. To contrast, only at high temperatures and\nfor large penetrants or when the dynamic heterogeneity effect is weak does the\neffect of mesh confinement become significant, even though penetrant diffusion\nmore broadly empirically follows similar trends as established models of mesh\nconfinement-based transport."
    },
    {
        "anchor": "Casimir-like forces at the percolation transition: Percolation and critical phenomena show common features such as scaling and\nuniversality. Colloidal particles, immersed in a solvent close to criticality,\nexperience long-range effective forces, named critical Casimir forces. %These\noriginate from the confinement of the solvent critical fluctuations between the\ncolloids. Building on the analogy between critical phenomena and percolation,\nwe explore the possibility of observing long-range forces near a percolation\nthreshold. To this aim we numerically evaluate the effective potential between\ntwo colloidal particles dispersed in a chemical sol and we show that it becomes\nattractive and long-ranged on approaching the sol percolation transition. We\ndevelop a theoretical description based on a polydisperse Asakura-Oosawa model\nwhich captures the divergence of the interaction range, allowing us to\ninterpret such effect in terms of depletion interactions in a structured\nsolvent. Our results provide the geometric analogue of the critical Casimir\nforce, suggesting a novel way for tuning colloidal interactions by controlling\nthe clustering properties of the solvent.",
        "positive": "The influence of line tension on the formation of liquid bridges: The formation of liquid bridges between a planar and conical substrates is\nanalyzed macroscopically taking into account the line tension. Depending on the\nvalue of the line tension coefficient \\tau and geometric parameters of the\nsystem one observes two different scenarios of liquid bridge formation upon\nchanging the fluid state along the bulk liquid-vapor coexistence. For \\tau >\n\\tau * (\\tau * < 0) there is a first-order transition to a state with\ninfinitely thick liquid bridge. For \\tau < \\tau * the scenario consists of two\nsteps: first there is a first-order transition to a state with liquid bridge of\nfinite thickness which upon further increase of temperature is followed by\ncontinuous growth of the thickness of the bridge to infinity. In addition to\nconstructing the relevant phase diagram we examine the dependence of the width\nof the bridge on thermodynamic and geometric parameters of the system."
    },
    {
        "anchor": "Simple shear is not so simple: For homogeneous, isotropic, nonlinearly elastic materials, the form of the\nhomogeneous deformation consistent with the application of a Cauchy shear\nstress is derived here for both compressible and incompressible materials. It\nis shown that this deformation is not simple shear, in contrast to the\nsituation in linear elasticity. Instead, it consists of a triaxial stretch\nsuperposed on a classical simple shear deformation, for which the amount of\nshear cannot be greater than 1. In other words, the faces of a cubic block\ncannot be slanted by an angle greater than 45deg by the application of a pure\nshear stress alone. The results are illustrated for those materials for which\nthe strain energy function does not depend on the principal second invariant of\nstrain. For the case of a block deformed into a parallelepiped, the tractions\non the inclined faces necessary to maintain the derived deformation are\ncalculated.",
        "positive": "Viscoelasticity of two-layer-vesicles in solution: The dynamic shape relaxation of the two-layer-vesicle is calculated. In\nadditional to the undulation relaxation where the two bilayers move in the same\ndirection, the squeezing mode appears when the gap between the two bilayers is\nsmall. At large gap, the inner vesicle relaxes much faster, whereas the slow\nmode is mainly due to the outer layer relaxation. We have calculated the\nviscoelasticity of the dilute two-layer-vesicle suspension. It is found that\nfor small gap, the applied shear drives the undulation mode strongly while the\nslow squeezing mode is not much excited. In this limit the complex viscosity is\ndominated by the fast mode contribution. On the other hand, the slow mode is\nstrongly driven by shear for larger gap. We have determined the crossover gap\nwhich depends on the interaction between the two bilayers. For a series of\nsamples where the gap is changed systematically, it is possible to observe the\ntwo amplitude switchings."
    },
    {
        "anchor": "Scaling regimes for wormlike chains confined to cylindrical surfaces\n  under tension: We compute the free energy of confinement ${\\cal{F}}$ for a wormlike chain\n(WLC), with persistence length $l_p$, that is confined to the surface of a\ncylinder of radius $R$ under an external tension $f$ using a mean field\nvariational approach. For long chains, we analytically determine the behavior\nof the chain in a variety of regimes, which are demarcated by the interplay of\n$l_p$, the Odijk deflection length ($l_d=(R^2l_p)^{1/3}$), and the Pincus\nlength ($l_f = {k_BT}/{f}$, with $k_BT$ being the thermal energy). The theory\naccurately reproduces the Odijk scaling for strongly confined chains at $f=0$,\nwith ${\\cal{F}}\\sim Ll_p^{-1/3}R^{-2/3}$. For moderate values of $f$, the Odijk\nscaling is discernible only when ${l_p}\\gg R$ for strongly confined chains.\nConfinement does not significantly alter the scaling of the mean extension for\nsufficiently high tension. The theory is used to estimate unwrapping forces for\nDNA from nucleosomes.",
        "positive": "Discontinuous change of shear modulus for frictional jammed granular\n  materials: The shear modulus of jammed frictional granular materials with the harmonic\nrepulsive interaction under an oscillatory shear is numerically investigated.\nIt is confirmed that the storage modulus, the real part of the shear modulus,\nfor frictional grains with sufficiently small strain amplitude $\\gamma_0$\ndiscontinuously emerges at the jamming transition point. The storage modulus\nfor small $\\gamma_0$ differs from that of frictionless grains even in the zero\nfriction limit, while they are almost identical with each other for\nsufficiently large $\\gamma_0$, where the transition becomes continuous. The\nstress-strain curve exhibits a hysteresis loop even for a small strain, which\nconnects a linear region for sufficiently small strain to another linear region\nfor relatively larger strain. We propose a new scaling law to interpolate\nbetween the states of small and large $\\gamma_0$."
    },
    {
        "anchor": "Four stages of droplet spreading on a spherical substrate and in a\n  spherical cavity -Surface tension vs line tension and viscous dissipation vs\n  frictional dissipation-: The spreading of a cap-shaped spherical droplet of non-Newtonian power-law\nliquids on a completely wettable spherical substrate is theoretically studied.\nBoth convex spherical substrates and concave spherical cavities with smooth or\nrough surfaces are considered. The droplet on a rough substrate is modeled by\neither the Wenzel or the Cassie-Baxter model. The two sources of driving force\nof spreading by the surface-tension and the line tension are considered. Also,\nthe two channels of energy dissipation by the viscous dissipation within the\nbulk and the frictional dissipation at the contact line are considered. A\ncombined theory of spreading on a spherical substrate is constructed by\nincluding those four factors. The spreading process is divided into four\nstages, each of which is governed by one of two driving forces and one of two\ndissipations. It is found that the dynamic contact angle $\\theta$ has a\ncharacteristic time ($t$) dependence at each stage. It does not necessarily\nfollow the standard power law $\\theta \\sim t^{-\\alpha}$. Instead, the\nrelaxation can be a power-law with the exponent $\\alpha$ different from that on\na flat substrate, or it can be exponential or it can finish within a finite\ntime. Therefore, various spreading scenarios on a spherical substrate and in a\nspherical cavity are predicted.",
        "positive": "Scaling Laws for Spreading of a Liquid Under Pressure: We study squeeze flow of two different fluids (castor oil and ethylene\nglycol) between a pair of glass plates and a pair of perspex plates, under an\napplied load. The film thickness is found to vary with time as a power-law,\nwhere the exponent increases with load. After a certain time interval the area\nof fluid-solid contact saturates to a constant value. This saturation area,\nincreases with load at different rates for different fluid-solid combinations."
    },
    {
        "anchor": "Stochastic jetting and dripping in confined soft granular flows: We report new dynamical modes in confined soft granular flows, such as\nstochastic jetting and dripping, with no counterpart in continuum viscous\nfluids. The new modes emerge as a result of the propagation of the chaotic\nbehaviour of individual grains -- here, monodisperse emulsion droplets to the\nlevel of the entire system as the emulsion is focused into a narrow orifice by\nan external viscous flow. We observe avalanching dynamics and the formation of\nremarkably stable jets -- singlefile granular chains -- which occasionally\nbreak, resulting in a non-Gaussian distribution of cluster sizes. We find that\nthe sequences of droplet rearrangements that lead to the formation of such\nchains resemble unfolding of cancer cell clusters in narrow capillaries,\noverall demonstrating that microfluidic emulsion systems could serve to model\nvarious aspects of soft granular flows, including also tissue dynamics at the\nmeso-scale.",
        "positive": "Bulk modulus of the nanoparticle system in concentrated magnetic fluids\n  and local field-induced structural anisotropy: In the present study we probe the bulk modulus and the structure of\nconcentrated magnetic fluids by Small Angle X-ray Scattering. The\nelectrostatically stabilized nanoparticles experience a repulsive interparticle\npotential modulated by dipolar magnetic interactions. On the interparticle\ndistance lengthscale, we show that nanoparticles are trapped under-field in\noblate cages formed by their first neighbours. We propose a theoretical model\nof magnetostriction for the field-induced deformation of the cage. This model\ncaptures the anisotropic features of the experimentally observed scattering\npattern on the local scale in these strongly interacting colloidal dispersions."
    },
    {
        "anchor": "Global perspectives on the energy landscapes of liquids, supercooled\n  liquids, and glassy systems: Geodesic pathways through the potential energy\n  landscape: How useful it is to think about the potential energy landscape of a complex\nmany-body system depends in large measure on how direct the connection is to\nthe system's dynamics. In this paper we show that, within what we call the\npotential energy landscape ensemble, it is possible to make direct connections\nbetween the geometry of the landscape and the long-time dynamical behaviors of\nsystems such as supercooled liquids. We show, in particular, that the onset of\nslow dynamics in such systems is governed directly by the lengths of their\ngeodesics - the shortest paths through their landscapes within the special\nensemble. The more convoluted and labyrinthine these geodesics are, the slower\nthat dynamics is. Geodesics in the landscape ensemble have sufficiently\nwell-defined characteristics that is straightforward to search for them\nnumerically, a point we illustrate by computing the geodesic lengths for an\nordinary atomic liquid and a binary glass-forming atomic mixture. We find that\nthe temperature dependence of the diffusion constants of these systems,\nincluding the precipitous drop as the glass-forming system approaches its\nmode-coupling transition, is predicted quantitatively by the growth of the\ngeodesic path lengths.",
        "positive": "Phase behavior and material properties of hollow nanoparticles: Effective pair potentials for hollow nanoparticles like the ones made from\ncarbon (fullerenes) or metal dichalcogenides (inorganic fullerenes) consist of\na hard core repulsion and a deep, but short-ranged, van der Waals attraction.\nWe investigate them for single- and multi-walled nanoparticles and show that in\nboth cases, in the limit of large radii the interaction range scales inversely\nwith the radius, $R$, while the well depth scales linearly with $R$. We predict\nthe values of the radius $R$ and the wall thickness $h$ at which the gas-liquid\ncoexistence disappears from the phase diagram. We also discuss unusual material\nproperties of the solid, which include a large heat of sublimation and a small\nsurface energy."
    },
    {
        "anchor": "Effects of Polydispersity on the Plastic Behaviors of Dense 2D Granular\n  Systems Under Shear: We study particle-scale motion in sheared highly polydisperse amorphous\nmaterials, in which the largest particles are as much as ten times the size of\nthe smallest. We find strikingly different behavior from the more commonly\nstudied amorphous systems with low polydispersity. In particular, analysis of\nthe nonaffine motion of particles reveals qualitative differences between large\nand small particles: the smaller particles have dramatically more nonaffine\nmotion, which is induced by the presence of the large particles. We\ncharacterize the crossover in nonaffine motion from the low- to\nhigh-polydispersity regime, and demonstrate a quantitative way to distinguish\nbetween \"large\" and \"small\" particles in systems with broad distributions of\nparticle sizes.",
        "positive": "Colloidal transport in bacteria suspensions: from bacteria scattering to\n  anomalous and enhanced diffusion: Colloids coupled to a bath of swimming cells generically display enhanced\ndiffusion. This transport dynamics stems from a subtle interplay between the\nactive and passive particles that still resists our understanding despite\ndecades of intense research. Here, we tackle the root of the problem by\nproviding a quantitative characterisation of the single scattering events\nbetween a colloid and a bacterium. Based on our experiments, we build a minimal\nmodel that quantitatively predicts the geometry of the scattering trajectories,\nand enhanced colloidal diffusion at long times. This quantitative confrontation\nbetween theory and experiments elucidates the microscopic origin of enhanced\ntransport. Collisions are solely ruled by stochastic contact interactions\nresponsible both for genuine anomalous diffusion at short times and enhanced\ndiffusion at long times with no ballistic regime at any scale."
    },
    {
        "anchor": "Dynamics and rheology under continuous shear flow studied by X-ray\n  photon correlation spectroscopy: X-ray Photon Correlation Spectroscopy (XPCS) has emerged as a unique\ntechnique allowing the measurement of dynamics in materials on mesoscopic\nlengthscales. In particular, applications in soft matter physics cover a broad\nrange of topics which include, but are not limited to, nanostructured materials\nsuch as colloidal suspensions or polymers, dynamics at liquid surfaces,\nmembranes and interfaces, and the glass or gel transition. One of the most\ncommon problems associated with the use of bright X-ray beams with soft\nmaterials is beam induced radiation damage, and this is likely to become an\neven more limiting factor at future synchrotron and free electron laser\nsources. Flowing the sample during data acquisition is one of the simplest\nmethod allowing to limit the radiation damage. In addition to distributing the\ndose over many different scatterers, the method also enables new\nfunctionalities such as time-resolved studies in mixing cells. Here, we further\ndevelop an experimental technique that was recently proposed combining XPCS and\ncontinuously flowing samples. More specifically, we use a model system to show\nhow the macroscopic advective response to flow and the microscopic dissipative\ndynamics (diffusion) can be quantified from the X-ray data. The method has many\npotential applications, e.g. dynamics of glasses and gels under continuous\nshear/flow, protein aggregations processes, the interplay between dynamics and\nrheology in complex fluids.",
        "positive": "Optical Studies of Zero-Field Magnetization of CdMnTe Quantum Dots:\n  Influence of Average Size and Composition of Quantum Dots: We show that through the resonant optical excitation of spin-polarized\nexcitons into CdMnTe magnetic quantum dots, we can induce a macroscopic\nmagnetization of the Mn impurities. We observe very broad (4 meV linewidth)\nemission lines of single dots, which are consistent with the formation of\nstrongly confined exciton magnetic polarons. Therefore we attribute the\noptically induced magnetization of the magnetic dots results to the formation\nof spin-polarized exciton magnetic polarons. We find that the photo-induced\nmagnetization of magnetic polarons is weaker for larger dots which emit at\nlower energies within the QD distribution. We also show that the photo-induced\nmagnetization is stronger for quantum dots with lower Mn concentration, which\nwe ascribe to weaker Mn-Mn interaction between the nearest neighbors within the\ndots. Due to particular stability of the exciton magnetic polarons in QDs,\nwhere the localization of the electrons and holes is comparable to the magnetic\nexchange interaction, this optically induced spin alignment persists to\ntemperatures as high as 160 K."
    },
    {
        "anchor": "Effect of Laponite on the structure, thermal stability and barrier\n  properties of nanocomposite gelatin films: The effect of Laponite (a synthetic clay) on the structure, thermal and water\nvapor barrier properties of nanocomposite gelatin films produced by casting\nwith 0, 4.5 and 15% w Lap/w gelatin, was studied. X-ray diffraction,\ndifferential scanning calorimetry, thermogravimetric analysis and Fourier\ntransform infrared spectroscopy measurements were reported. The X-ray\ndiffraction patterns showed dual crystalline structure of the films with\ncollagen-type bundles of triple helices, intercalated inside clay platelets,\nincreasing interlayer distances. Depending on the renaturation of\ntriple-helices and Laponite content, the glass transition temperatures\nsubstantially decreased. The amount of helices decreased with Lap\nconcentration, affecting the enthalpy of melting. The nanocomposite gelatin\nfilms showed improved thermal stability. Changes of water vapor permeability\ncould be related to the presence of larger free volume of the coils and\nintercalated structures, facilitating water transfer through the film.",
        "positive": "Phase Behavior of Polyelectrolyte-Surfactant Complexes at Planar\n  Surfaces: We investigate theoretically the phase diagram of an insoluble charged\nsurfactant monolayer in contact with a semi-dilute polyelectrolyte solution (of\nopposite charge). The polyelectrolytes are assumed to have long-range and\nattractive (electrostatic) interaction with the surfactant molecules. In\naddition, we introduce a short-range (chemical) interaction which is either\nattractive or repulsive. The surfactant monolayer can have a lateral phase\nseparation between dilute and condensed phases. Three different regimes of the\ncoupled system are investigated depending on system parameters. A regime where\nthe polyelectrolyte is depleted due to short range repulsion from the surface,\nand two adsorption regimes, one being dominated by electrostatics, whereas the\nother by short range chemical attraction (similar to neutral polymers). When\nthe polyelectrolyte is more attracted (or at least less repelled) by the\nsurfactant molecules as compared with the bare water/air interface, it will\nshift upwards the surfactant critical temperature. For repulsive short-range\ninteractions the effect is opposite. Finally, the addition of salt to the\nsolution is found to increase the critical temperature for attractive surfaces,\nbut does not show any significant effect for repulsive surfaces."
    },
    {
        "anchor": "Depletion-induced percolation in networks of nanorods: Above a certain density threshold, suspensions of rod-like colloidal\nparticles form system-spanning networks. Using Monte Carlo simulations, we\ninvestigate how the depletion forces caused by spherical particles affect these\nnetworks in isotropic suspensions of rods. Although the depletion forces are\nstrongly anisotropic and favor alignment of the rods, the percolation threshold\nof the rods decreases significantly. The relative size of the effect increases\nwith the aspect ratio of the rods. The structural changes induced in the\nsuspension by the depletant are characterized in detail and the system is\ncompared to an ideal fluid of freely interpenetrable rods.",
        "positive": "Fundamentals of the Oldroyd-B model revisited: Tensorial vs. vectorial\n  theory: The standard derivation of the Oldroyd-B model starts from a coupled system\nof the momentum equation for the macroscopic flow on the one hand, and\nFokker-Planck dynamics for molecular dumbbells on the other. The constitutive\nequation is then derived via a closure based upon the second moment of the\nend-to-end vector distribution. We here present an alternative closure that is\nrather based upon the first moment, and gives rise to an even simpler\nconstitutive equation. We establish that both closures are physically sound,\nsince both can be derived from (different) well-defined non-equilibrium\nensembles, and both are consistent with the Second Law of thermodynamics. In\ncontrast to the standard model, the new model has a free energy and a\ndissipation rate that are both regular at vanishing conformation tensor. We\nspeculate that this might perhaps alleviate the well-known high Weissenberg\nnumber problem, i. e. severe numerical instabilities of the standard model at\nlarge flow rates. As the new model permits a trivial solution (vanishing\nconformation tensor, vanishing polymer stress), an extension may be needed,\nwhich includes Langevin noise in order to model thermal fluctuations."
    },
    {
        "anchor": "Fractal Analysis of Protein Potential Energy Landscapes: The fractal properties of the total potential energy V as a function of time\nt are studied for a number of systems, including realistic models of proteins\n(PPT, BPTI and myoglobin). The fractal dimension of V(t), characterized by the\nexponent \\gamma, is almost independent of temperature and increases with time,\nmore slowly the larger the protein. Perhaps the most striking observation of\nthis study is the apparent universality of the fractal dimension, which depends\nonly weakly on the type of molecular system. We explain this behavior by\nassuming that fractality is caused by a self-generated dynamical noise, a\nconsequence of intermode coupling due to anharmonicity. Global topological\nfeatures of the potential energy landscape are found to have little effect on\nthe observed fractal behavior.",
        "positive": "Theoretical study of I-V characteristics in a coupled long Josephson\n  junctions based on magnesium diboride superconductor: In the present work, the current-voltage (I-V) characteristics in a coupled\nlong Josephson junction based on magnesium diboride are studied by establishing\na system of equations of phase differences of various inter- and intra-band\nchannels starting from the microscopic Hamiltonian of the junction system and\nsimplifying it through the phenomenological procedures such as action,\npartition function, Hubbard-Stratonovich transformation (bosonization),\nGrassmann integral, saddle-point approximation, Goldstone mode, phase dependent\neffective Lagrangian and, finally, Euler-Lagrange equation of motion. The\nsystem of equations are solved using finite difference approximation for which\nthe solution of unperturbed sine-Gordon equation is taken as the initial\ncondition. Neumann boundary condition is maintained at both the ends so that\nthe fluxon is capable of reflecting from the end of the system. The phase\ndependent current is calculated for different tunnel voltage and averaged out\nover space and time. The current-voltage characteristics are almost linear at\nlow voltage and non-linear at higher voltage which indicates that the more\ncomplicated physical phenomena at this situation may occur. At some region of\nthe characteristics, there exist a negative resistance which means that the\njunction system can be used in specific electronic devices such as oscillators,\nswitches, memories etc. The non-linearity is also sensitive to the layer as\nwell as to the junction thicknesses. Non-linearity occurs for lower voltage and\nfor higher junction and layer thicknesses."
    },
    {
        "anchor": "Brownian motion of a charged colloid in restricted confinement: We study the Brownian motion of a charged colloid, confined between two\ncharged walls, for small separation between the colloid and the walls. The\nsystem is embedded in an ionic solution. The combined effect of electrostatic\nrepulsion and reduced diffusion due to hydrodynamic forces results in a\nspecific motion in the direction perpendicular to the confining walls. The\napparent diffusion coefficient at short times as well as the diffusion\ncharacteristic time are shown to follow a sigmoid curve as function of a\ndimensionless parameter. This parameter depends on the electrostatic properties\nand can be controlled by tuning the solution ionic strength. At low ionic\nstrength, the colloid moves faster and is localized, while at high ionic\nstrength it moves slower and explores a wider region between the walls,\nresulting in a larger diffusion characteristic time.",
        "positive": "Differential capacitance of the electric double layer: The interplay\n  between ion finite size and dielectric decrement: We study the electric double layer by combining the effects of ion finite\nsize and dielectric decrement. At high surface potential, both mechanisms can\ncause saturation of the counter-ion concentration near a charged surface. The\nmodified Grahame equation and differential capacitance are derived analytically\nfor a general expression of a permittivity epsilon(n) that depends on the local\nion concentration, n, and under the assumption that the co-ions are fully\ndepleted from the surface. The concentration at counter-ion saturation is found\nfor any epsilon(n), and a criterion predicting which of the two mechanisms\n(steric vs. dielectric decrement) is the dominant one is obtained. At low\nsalinity, the differential capacitance as function of surface potential has two\npeaks (so-called camel-shape). Each of these two peaks is connected to a\nsaturation of counter-ion concentration caused either by dielectric decrement\nor by their finite size. Because these effects depend mainly on the counter-ion\nconcentration at the surface proximity, for opposite surface-potential polarity\neither the cations or anions play the role of counter-ions, resulting in an\nasymmetric camel-shape. At high salinity, we obtain and analyze the crossover\nin the differential capacitance from a double-peak shape to a uni-modal one.\nFinally, several nonlinear models of the permittivity decrement are considered,\nand we predict that the concentration at dielectrophoretic saturation shifts to\nhigher concentration than those obtained by the linear decrement model."
    },
    {
        "anchor": "Equilibrium Configurations and Energetics of Point Defects in\n  Two-Dimensional Colloidal Crystals: We demonstrate a novel method of introducing point defects (mono and\ndi-vacancies) in a confined mono-layer colloidal crystal by manipulating\nindividual particles with optical tweezers. Digital video microscopy is used to\nstudy defect dynamics in real space and time. We analyze the topological\narrangements of the particles in the defect core and establish their connection\nwith the energetics of the system. It is found that thermal fluctuations excite\npoint defects into \\textit{dislocation multipole} configurations. We extract\nthe dislocation pair potential at near field, where cores overlap and linear\nelasticity is not applicable.",
        "positive": "A variational approach to the moving contact line hydrodynamics: In immiscible two-phase flows, contact line denotes the intersection of the\nfluid-fluid interface with the solid wall. When one fluid displaces the other,\nthe contact line moves along the wall. A classical problem in continuum\nhydrodynamics is the incompatibility between the moving contact line and the\nno-slip boundary condition, as the latter leads to a non-integrable\nsingularity. The recently discovered generalized Navier boundary condition\n(GNBC) offers an alternative to the no-slip boundary condition which can\nresolve the moving contact line conundrum. We present a variational derivation\nof the GNBC through the principle of minimum energy dissipation (entropy\nproduction), as formulated by Onsager for small perturbations away from the\nequilibrium. Through numerical implementation of a continuum hydrodynamic\nmodel, it is demonstrated that the GNBC can quantitatively reproduce the moving\ncontact line slip velocity profiles obtained from molecular dynamics\nsimulations. In particular, the transition from complete slip at the moving\ncontact line to near-zero slip far away is shown to be governed by a power-law\npartial slip regime, extending to mesoscopic length scales. The sharp\n(fluid-fluid) interface limit of the hydrodynamic model, together with some\ngeneral implications of slip versus no-slip, are discussed."
    },
    {
        "anchor": "Swinging and Tumbling of Fluid Vesicles in Shear Flow: The dynamics of fluid vesicles in simple shear flow is studied using\nmesoscale simulations of dynamically-triangulated surfaces, as well as a\ntheoretical approach based on two variables, a shape parameter and the\ninclination angle, which has no adjustable parameters. We show that between the\nwell-known tank-treading and tumbling states, a new ``swinging'' state can\nappear. We predict the dynamic phase diagram as a function of the shear rate,\nthe viscosities of the membrane and the internal fluid, and the reduced vesicle\nvolume. Our results agree well with recent experiments.",
        "positive": "Bifurcation instructed design of multistate machines: We propose a novel design paradigm for multistate machines where transitions\nfrom one state to another are organized by bifurcations of multiple equilibria\nof the energy landscape describing the collective interactions of the machine\ncomponents. This design paradigm is attractive since, near bifurcations, small\nvariations in a few control parameters can result in large changes to the\nsystem's state providing an emergent lever mechanism. Further, the topological\nconfiguration of transitions between states near such bifurcations ensures\nrobust operation, making the machine less sensitive to fabrication errors and\nnoise. To design such machines, we develop and implement a new efficient\nalgorithm that searches for interactions between the machine components that\ngive rise to energy landscapes with these bifurcation structures. We\ndemonstrate a proof of concept for this approach by designing magneto elastic\nmachines whose motions are primarily guided by their magnetic energy landscapes\nand show that by operating near bifurcations we can achieve multiple transition\npathways between states. This proof of concept demonstration illustrates the\npower of this approach, which could be especially useful for soft robotics and\nat the microscale where typical macroscale designs are difficult to implement."
    },
    {
        "anchor": "3D Printed Architectured Silicones with Autonomic Self-healing and\n  Creep-resistant Behavior: Self-healing silicones that are able to restore the functionalities and\nextend the lifetime of soft devices hold great potential in many applications.\nHowever, currently available silicones need to be triggered to self-heal or\nsuffer from creep-induced irreversible deformation during use. Here, we design\nand print silicone objects that are programmed at the molecular and\narchitecture levels to achieve self-healing at room temperature while\nsimultaneously resisting creep. At the molecular scale, dioxaborolanes moieties\nare incorporated into silicones to synthesize self-healing vitrimers, whereas\nconventional covalent bonds are exploited to make creep-resistant elastomers.\nWhen combined into architectured printed parts at a coarser length scale,\nlayered materials exhibit fast healing at room temperature without compromising\nthe elastic recovery obtained from covalent polymer networks. A\npatient-specific vascular phantom is printed to demonstrate the potential of\narchitectured silicones in creating damage-resilient functional devices using\nmolecularly designed elastomer materials.",
        "positive": "Directed transport of suspended ferromagnetic nanoparticles under both\n  gradient and uniform magnetic fields: The suspended ferromagnetic particles subjected to the gradient and uniform\nmagnetic fields experience both the translational force generated by the field\ngradient and the rotational torque generated by the fields strengths. Although\nthe uniform field does not contribute to the force, it nevertheless influences\nthe translational motion of these particles. This occurs because the\ntranslational force depends on the direction of the particle magnetization,\nwhich in turn depends on the fields strengths. To study this influence, a\nminimal set of equations describing the coupled translational and rotational\nmotions of nanosized ferromagnetic particles is introduced and solved in the\nlow Reynolds number approximation. Trajectory analysis reveals that, depending\non the initial positions of nanoparticles, there exist four regimes of their\ndirected transport. The intervals of initial positions that correspond to\ndifferent dynamical regimes are determined, their dependence on the uniform\nmagnetic field is established, and strong impact of this field on the directed\ntransport is demonstrated. The ability and efficiency of the uniform magnetic\nfield to control the separation of suspended ferromagnetic nanoparticles is\nalso discussed."
    },
    {
        "anchor": "Parity Breaking in Nematic Tactoids: We theoretically investigate under what conditions the director field in a\nspindle-shaped nematic droplet or tactoid obtains a twisted, parity-broken\nstructure. By minimizing the sum of the bulk elastic and surface energies, we\nshow that a twisted director field is stable if the twist and bend elastic\nconstants are small enough compared to the splay elastic constant, but only if\nthe droplet volume is larger than some minimum value. We furthermore show that\nthe transition from an untwisted to a twisted director-field structure is a\nsharp function of the various control parameters. We predict that suspensions\nof rigid, rod-like particles cannot support droplets with a parity broken\nstructure, whereas they could possibly occur in those of semi-flexible,\nworm-like particles.",
        "positive": "Chiral Discotic Columnar Phases in Liquid Crystals: We introduce a model to describe columnar phases of chiral discotic liquid\nphases in which the normals to disc-like molecules are constrained to lie\nparallel to columnar axes. The model includes separate chiral interactions\nfavoring, respectively, relative twist of chiral molecules along the axes of\nthe columns and twist of the two-dimensional columnar lattice. It also includes\na coupling between the lattice and the orientation of the discotic molecules.\nWe discuss the instability of the aligned hexagonal lattice phase to the\nformation of a soliton lattice in which molecules twist within their columns\nwithout affecting the lattice and to the formation of a moir\\'{e} phase\nconsisting of a periodic array of twist grain boundaries perpendicular to the\ncolumns."
    },
    {
        "anchor": "Equilibrium conformations and surface charge regulation of spherical\n  polymer brushes in stretched regimes: In the present work, we study the equilibrium conformations of linear\npolyelectrolytes tethered onto a spherical, oppositely charged core in\nequilibrium with an ionic reservoir of fixed concentration. Particular focus is\nplaced on the situation of stretched chains, where the monomer concentration is\nknown to display an inverse square-law decay far away from the spherical\nsurface, which is then further extrapolated all the way down to the grafting\ncore. While the equilibrium distributions of mobile ions are computed in the\nframework of a classical Density Functional Theory (cDFT) that incorporates\nboth their size and electrostatic correlations within the grafted\npolyelectrolyte, the equilibrium configuration of the latter is described by\nits averaged radius of gyration, which is taken as a variational parameter that\nguarantees mechanical equilibrium across the polymer-solvent interface. The\naveraged particle size is then analyzed over a wide range of polymerization\ndegrees, ionic concentrations and functionality of the polymer backbones. Two\ndistinct regimes can be identified: at high ionic strengths, swelling of the\ngrafted polymers is dominated by ionic entropic contribution as well as polymer\nsize effects, whereas at low ionic concentrations a balance between\nelectrostatic and entropic effects is the main driven mechanism for particle\nstretching. Using Monte Carlo simulations, we then proceed to investigate the\neffects of charge regulation when the brush core is further decorated with\nactive functional sites randomly distributed over its surface, which act as\nreceptors onto which dissolved acidic ions can be adsorbed.",
        "positive": "Intermittent permeation of cylindrical nanopores by water: Molecular Dynamics simulations of water molecules in nanometre sized\ncylindrical channels connecting two reservoirs show that the permeation of\nwater is very sensitive to the channel radius and to electric polarization of\nthe embedding material. At threshold, the permeation is {\\emph{intermittent}}\non a nanosecond timescale, and strongly enhanced by the presence of an ion\ninside the channel, providing a possible mechanism for gating. Confined water\nremains surprisingly fluid and bulk-like. Its behaviour differs strikingly from\nthat of a reference Lennard-Jones fluid, which tends to contract into a highly\nlayered structure inside the channel."
    },
    {
        "anchor": "Interatomic repulsion softness directly controls the fragility of\n  supercooled metallic melts: We present an analytic scheme to connect the fragility and viscoelasticity of\nmetallic glasses to the effective ion-ion interaction in the metal. This is\nachieved by an approximation of the short-range repulsive part of the\ninteraction, combined with nonaffine lattice dynamics to obtain analytical\nexpressions for the shear modulus, viscosity, and fragility in terms of the\nion-ion interaction. By fitting the theoretical model to experimental data, we\nare able to link the steepness of the interionic repulsion to the Thomas-Fermi\nscreened Coulomb repulsion and to the Born-Mayer valence-electron overlap\nrepulsion for various alloys. The result is a simple closed-form expression for\nthe fragility of the supercooled liquid metal in terms of few crucial\natomic-scale interaction and anharmonicity parameters. In particular, a linear\nrelationship is found between the fragility and the energy scales of both the\nscreened Coulomb and the electron-overlap repulsions. This relationship opens\nup opportunities to fabricate alloys with tailored thermo-elasticity and\nfragility by rationally tuning the chemical composition of the alloy according\nto general principles. The analysis presented here brings a new way of looking\nat the link between the outer-shell electronic structure of metals and\nmetalloids and the viscoelasticity and fragility thereof.",
        "positive": "Self-assembly of colloidal bands driven by a periodic external field: We study the formation of bands of colloidal particles driven by periodic\nexternal fields. Using Brownian dynamics, we determine the dependence of the\nband width on the strength of the particle interactions and on the intensity\nand periodicity of the field. We also investigate the switching (field-on)\ndynamics and the relaxation times as a function of the system parameters. The\nobserved scaling relations were analyzed using a simple dynamic\ndensity-functional theory of fluids."
    },
    {
        "anchor": "Dynamical Heterogeneities and Cooperative Motion in Smectic Liquid\n  Crystals: Using simulations of hard rods in smectic-A states, we find non-gaussian\ndiffusion and heterogeneous dynamics due to the equilibrium periodic smectic\ndensity profiles, which give rise to permanent barriers for layer-to-layer\ndiffusion. This relaxation behavior is surprisingly similar to that of\nnon-equilibrium supercooled liquids, although there the particles are trapped\nin transient (instead of permanent) cages. Interestingly, we also find\nstringlike clusters of up to 10 inter-layer rods exhibiting dynamic\ncooperativity in this equilibrium state.",
        "positive": "Equilibrium sampling by re-weighting non-equilibrium simulation\n  trajectories: With the traditional equilibrium molecular simulations, it is usually\ndifficult to efficiently visit the whole conformational space in complex\nsystems, which are separated into some metastable conformational regions by\nhigh free energy barriers. The applied non-equilibrium process in simulations\ncould enhance the transitions among these conformational regions, and the\nassociated non-equilibrium effects can be removed by employing the Jarzynski\nequality (JE), then the global equilibrium distribution can be reproduced.\nHowever, the original JE requires the initial distribution of the\nnon-equilibrium process is equilibrium, which largely limits the application of\nthe non-equilibrium method in equilibrium sampling. By extending the previous\nmethod, the reweighted ensemble dynamics (RED), which re-weights many\nequilibrium simulation trajectories from arbitrary initial distribution to\nreproduce the global equilibrium, to non-equilibrium simulations, we present a\nmethod, named as re-weighted non-equilibrium ensemble dynamics (RNED), to\ngeneralize the JE in the non-equilibrium trajectories started from an arbitrary\ninitial distribution, thus provide an efficient method to reproduce the\nequilibrium distribution based on multiple independent (short) non-equilibrium\ntrajectories. We have illustrated the validity of the RNED in a one-dimensional\ntoy model and in a Lennard-Jones system to detect the liquid-solid phase\ncoexistence."
    },
    {
        "anchor": "Coarse-grained interaction potentials for polyaromatic hydrocarbons: Using Kohn-Sham density functional theory (KS-DFT), we have studied the\ninteraction between various polyaromatic hydrocarbon molecules. The systems\nrange from mono-cyclic benzene up to hexabenzocoronene (hbc). For several\nconventional exchange-correlation functionals potential energy curves of\ninteraction of the $\\pi$-$\\pi$ stacking hbc dimer are reported. It is found\nthat all pure local density or generalized gradient approximated functionals\nyield qualitatively incorrect predictions regarding structure and interaction.\nInclusion of a non-local, atom-centered correction to the KS-Hamiltonian\nenables quantitative predictions. The computed potential energy surfaces of\ninteraction yield parameters for a coarse-grained potential, which can be\nemployed to study discotic liquid-crystalline mesophases of derived\npolyaromatic macromolecules.",
        "positive": "Scalable Metropolis Monte Carlo for simulation of hard shapes: We design and implement HPMC, a scalable hard particle Monte Carlo simulation\ntoolkit, and release it open source as part of HOOMD-blue. HPMC runs in\nparallel on many CPUs and many GPUs using domain decomposition. We employ BVH\ntrees instead of cell lists on the CPU for fast performance, especially with\nlarge particle size disparity, and optimize inner loops with SIMD vector\nintrinsics on the CPU. Our GPU kernel proposes many trial moves in parallel on\na checkerboard and uses a block-level queue to redistribute work among threads\nand avoid divergence. HPMC supports a wide variety of shape classes, including\nspheres / disks, unions of spheres, convex polygons, convex spheropolygons,\nconcave polygons, ellipsoids / ellipses, convex polyhedra, convex\nspheropolyhedra, spheres cut by planes, and concave polyhedra. NVT and NPT\nensembles can be run in 2D or 3D triclinic boxes. Additional integration\nschemes permit Frenkel-Ladd free energy computations and implicit depletant\nsimulations. In a benchmark system of a fluid of 4096 pentagons, HPMC performs\n10 million sweeps in 10 minutes on 96 CPU cores on XSEDE Comet. The same\nsimulation would take 7.6 hours in serial. HPMC also scales to large system\nsizes, and the same benchmark with 16.8 million particles runs in 1.4 hours on\n2048 GPUs on OLCF Titan."
    },
    {
        "anchor": "Neutral and Charged Polymers at Interfaces: Chain-like macromolecules (polymers) show characteristic adsorption\nproperties due to their flexibility and internal degrees of freedom, when\nattracted to surfaces and interfaces. In this review we discuss concepts and\nfeatures that are relevant to the adsorption of neutral and charged polymers at\nequilibrium, including the type of polymer/surface interaction, the solvent\nquality, the characteristics of the surface, and the polymer structure. We pay\nspecial attention to the case of charged polymers (polyelectrolytes) that have\na special importance due to their water solubility. We present a summary of\nrecent progress in this rapidly evolving field. Because many experimental\nstudies are performed with rather stiff biopolymers, we discuss in detail the\ncase of semi-flexible polymers in addition to flexible ones. We first review\nthe behavior of neutral and charged chains in solution. Then, the adsorption of\na single polymer chain is considered. Next, the adsorption and depletion\nprocesses in the many-chain case are reviewed. Profiles, changes in the surface\ntension and polymer surface excess are presented. Mean-field and corrections\ndue to fluctuations and lateral correlations are discussed. The force of\ninteraction between two adsorbed layers, which is important in understanding\ncolloidal stability, is characterized. The behavior of grafted polymers is also\nreviewed, both for neutral and charged polymer brushes.",
        "positive": "Dynamics of vortex tangle without mutual friction in superfluid $^4$He: A recent experiment has shown that a tangle of quantized vortices in\nsuperfluid $^4$He decayed even at mK temperatures where the normal fluid was\nnegligible and no mutual friction worked. Motivated by this experiment, this\nwork studies numerically the dynamics of the vortex tangle without the mutual\nfriction, thus showing that a self-similar cascade process, whereby large\nvortex loops break up to smaller ones, proceeds in the vortex tangle and is\nclosely related with its free decay. This cascade process which may be covered\nwith the mutual friction at higher temperatures is just the one at zero\ntemperature Feynman proposed long ago. The full Biot-Savart calculation is made\nfor dilute vortices, while the localized induction approximation is used for a\ndense tangle. The former finds the elementary scenario: the reconnection of the\nvortices excites vortex waves along them and makes them kinked, which could be\nsuppressed if the mutual friction worked. The kinked parts reconnect with the\nvortex they belong to, dividing into small loops. The latter simulation under\nthe localized induction approximation shows that such cascade process actually\nproceeds self-similarly in a dense tangle and continues to make small vortices.\nConsidering that the vortices of the interatomic size no longer keep the\npicture of vortex, the cascade process leads to the decay of the vortex line\ndensity. The presence of the cascade process is supported also by investigating\nthe classification of the reconnection type and the size distribution of\nvortices. The decay of the vortex line density is consistent with the solution\nof the Vinen's equation which was originally derived on the basis of the idea\nof homogeneous turbulence with the cascade process. The obtained result is\ncompared with the recent Vinen's theory."
    },
    {
        "anchor": "Graphoepitaxy for Pattern Multiplication of Nanoparticle Monolayers: We compute the free energy minimizing structures of particle monolayers in\nthe presence of enthalpic barriers of a finite height \\b{eta}Vext using\nclassical density functional theory and Monte Carlo simulations. We show that a\nperiodic square template with dimensions up to at least ten times the particle\ndiameter disrupts the formation of the entropically favored hexagonally\nclose-packed 2D lattice in favor of a square lattice. The results illustrate\nhow graphoepitaxy can successfully order nanoparticulate films into desired\npatterns many times smaller than those of the prepatterned template.",
        "positive": "Ambipolar blends of CuPc and C60: charge carrier mobility, electronic\n  structure and its implications for solar cell applications: Ambipolar transport has been realised in blends of the molecular hole\nconductor Cu-phthalocyanine (CuPc) and the electron conducting fullerene C60.\nCharge carrier mobilities and the occupied electronic levels have been analyzed\nas a function of the mixing ratio using field-effect transistor measurements\nand photoelectron spectroscopy. These results are discussed in the context of\nphotovoltaic cells based on these materials."
    },
    {
        "anchor": "Dynamics of Mass Polar Spheroids During Sedimentation: The dynamics of sedimenting particles under gravity are surprisingly complex\ndue to the presence of effective long-ranged forces. When the particles are\npolar with a well-defined symmetry axis and non-uniform density, recent\ntheoretical predictions suggest that prolate objects will repel and oblate ones\nwill weakly attract. We tested these predictions using mass polar proalte\nspheroids, which are composed of 2 mm spheres glued together. We probed\ndifferent aspect rations ($\\kappa$) and center of mass offsets ($\\chi$) by\ncombining spheres of different densities. Experiments were done in both\nquasi-two-dimensional (2D) and three=dimensional (3D) chambers. By optically\ntracking the motion of single particles, we found that the dynamics were\nwell-described by a reduced mobility matrix model that could be solved\nanalytically. Pairs of particles exhibited an effective repulsion, and their\nseparation roughly scaled as ~$(\\kappa-1)/\\chi^{0.39}$, i.e. particles that\nwere more prolate or had smaller mass asymmetry had stronger repulsion effects.\nIn 3D, particles with $\\chi>0$ were distributed more uniformly than $\\chi=0$\nparticles, and the degree of uniformity increased with $\\kappa$, indicating\nthat the effective 2-body repulsion manifests for a large number of particles.",
        "positive": "Surface band segregation and internal convection in rotating sphere\n  densely filled with granular material: Experiments: While granular segregation in partially filled containers has been studied\nextensively, granular dynamics in densely filled spheres is not fully\nunderstood. Here, surface band segregation and granular convection are reported\nin a rotating sphere of highly compacted glass beads. Distinct from\nRayleigh-Benard convection, granular convection has a butterfly-shaped\nstructure with vortexes of alternating layers of small/large beads, which is\nstable and independent of the sphere size. Two concentric interfaces at the\nzero tangential/norm flux are discovered, which divide the sphere into three\nlayers from the surface to the core. The law that governs the jamming dynamics\nin rotating spheres remains an open question."
    },
    {
        "anchor": "Fine-tuning the DNA conductance by intercalation of drug molecules: In this letter, we study the structure-transport property relationships of\nsmall ligand intercalated DNA molecules using a multiscale modelling approach\nwhere extensive ab-initio calculations are performed on numerous MD-simulated\nconfigurations of dsDNA and dsDNA intercalated with two different\nintercalators, ethidium and daunomycin. DNA conductance is found to increase by\none order of magnitude upon drug intercalation due to the local unwinding of\nthe DNA base pairs adjacent to the intercalated sites which leads to\nmodifications of the density-of-states in the near-Fermi energy region of the\nligand-DNA complex. Our study suggests that the intercalators can be used to\nenhance/tune the DNA conductance which opens new possibilities for their\npotential applications in nanoelectronics.",
        "positive": "Propagating Density Spikes in Light-Powered Motility-Ratchets: Combining experiments and computer simulations, we use a spatially periodic\nand flashing light-field to direct the motion of phototactic active colloids.\nHere, the colloids self-organize into a density spike pattern, which resembles\na shock wave and propagates over long distances, almost without dispersing. The\nunderlying mechanism involves a synchronization of the colloids with the\nlight-field, so that particles see the same intensity gradient each time the\nlight-pattern is switched on, but no gradient in between (for example). This\ncreates a pulsating transport whose strength and direction can be controlled\nvia the flashing protocol and the self-propulsion speed of the colloids. Our\nresults might be useful for drug delivery applications and can be used to\nsegregate active colloids by their speed."
    },
    {
        "anchor": "Transport of particles through RO membrane in steady state condition: Reverse Osmosis(RO) membranes are widespread nowadays for separating the\nsolvent from a solution. RO membranes are made of polymer matrix. Experiments\nshow changes in relative interaction of solvent and solute with RO membrane\nmatrix lead to changes in solvent permeation, solute rejection and fouling.\nHere we study microscopically separation of binary mixture through RO polymeric\nmembrane using Molecular dynamics simulation to rationalize the experimental\nobservations in terms a simple model. We find better solvent permeation and\nsolute rejection with increasing interaction between solute and membrane with\nincrease in fouling of solute inside membrane. We also find that stronger\nsolvent membrane interaction reduces fouling. However, this leads to poorer\nperformance of RO in terms of solvent permeation and solute rejection.",
        "positive": "Topological defects in solids with odd elasticity: Crystallography typically studies collections of point particles whose\ninteraction forces are the gradient of a potential. Lifting this assumption\ngenerically gives rise in the continuum limit to a form of elasticity with\nadditional moduli known as odd elasticity. We show that such odd elastic moduli\nmodify the strain induced by topological defects and their interactions, even\nreversing the stability of, otherwise, bound dislocation pairs. Beyond\ncontinuum theory, isolated dislocations can self propel via microscopic work\ncycles active at their cores that compete with conventional Peach-Koehler\nforces caused, for example, by an ambient torque density. We perform molecular\ndynamics simulations isolating active plastic processes and discuss their\nexperimental relevance to solids composed of spinning particles, vortex-like\nobjects, and robotic metamaterials."
    },
    {
        "anchor": "Fine tuning the electro-mechanical response of dielectric elastomers: We propose a protocol to model accurately the electromechanical behavior of\ndielectric elastomer membranes using experimental data of stress-stretch and\nvoltage-stretch tests. We show how the relationship between electric\ndisplacement and electric field can be established in a rational manner from\nthis data. Our approach demonstrates that the ideal dielectric model,\nprescribing linearity in the purely electric constitutive equation, is quite\naccurate at low-to-moderate values of the electric field and that, in this\nrange, the dielectric permittivity constant of the material can be deduced from\nstress-stretch and voltage-stretch data. Beyond the linearity range, more\nrefined couplings are required, possibly including a non-additive decomposition\nof the electro-elastic energy. We also highlight that the presence of vertical\nasymptotes in voltage-stretch data, often observed in the experiments just\nprior to failure, should not be associated with strain stiffening effects, but\ninstead with the rapid development of electrical breakdown.",
        "positive": "Revisiting the reentrant condensation of sparsely charged\n  polyelectrolytes induced by diluted multivalent salts: Interplay between\n  electrostatic and non-electrostatic interactions: We study the reentrant condensation of sparsely charged polyelectrolytes in\ndilute solutions of small multivalent salts, whose phase-transition mechanism\nremains poorly understood. Motivated by recent full atomic simulation results\nreported by the Caltech group on phase behaviors of polyelectrolytes in\npresence of multivalent salts (DOIs: 10.1021/acs.macromol.3c02437 and\n10.48550/arXiv.2311.11404), in this work we construct a simple but effective\nmean-field model which can rationalize the essential features of the reentrant\ncondensation including the phase diagram of sparsely charged polyelectrolyte.\nThe model unveils that the strong adsorption between the ionic monomers and\nmultivalent ions can be at the origin of the peculiar phenomenon that rather\nlow concentrations of multivalent salts trigger both collapse and re-entry\ntransitions. The analytical solution of the model indicates that a minimum of\ncoupling energy due to sharing multivalent salt ions between ionic monomers is\nessential for a phase transition to occur, which can explain the enigmatic\nobservation that the sparsely charged polyelectrolytes can only show phase\ntransition in a dilute solution of salts with selective multivalency. Our\nanalytical calculations also show that the incompatibility of the uncharged\nmoieties of the polyelectrolytes with water is critical to regulate phase\nbehaviors of sparsely charged polyelectrolytes in aqueous solutions. This is in\nagreement with recent experimental investigations on solution properties of\namphiphilic proteins. We envisage that this work will shed light on the\nunderstanding of phase transition in biological processes where the diluted\nmultivalent ions bound to biopolymers (such as RNAs and proteins) plays an\nessential role, which remains under debate."
    },
    {
        "anchor": "Emergent dynamics in excitable flow systems: Flow networks can describe many natural and artificial systems. We present a\nmodel for a flow system that allows for volume accumulation, includes conduits\nwith a non-linear relation between current and pressure difference, and can be\napplied to networks of arbitrary topology. The model displays complex dynamics,\nincluding self-sustained oscillations in the absence of any dynamics in the\ninputs and outputs. In this work we analytically show the origin of\nself-sustained oscillations for the 1D case. We numerically study the behavior\nof systems of arbitrary topology under different conditions: we discuss their\nexcitability, the effect of different boundary conditions and wave propagation\nwhen the network has regions of conduits with linear conductance.",
        "positive": "Single-molecule force spectroscopy: Practical limitations beyond Bell's\n  model: Single-molecule force spectroscopy experiments, as well as a number of other\nphysical systems, are governed by thermally activated transitions out of a\nmetastable state under the action of a steadily increasing external force. The\nmain observable in such experiments is the distribution of the forces, at which\nthe escape events occur. The challenge in interpreting the experimental data is\nto relate them to the microscopic system properties. We work out a maximum\nlikelihood approach and show that it is the optimal method to tackle this\nproblem. When fitting actual experimental data it is unavoidable to assume some\nfunctional form for the force-dependent escape rate. We consider a quite\ngeneral and common such functional form and demonstrate by means of data from a\nrealistic computer experiment that the maximum number of fit parameters that\ncan be determined reliably is three. They are related to the force-free escape\nrate and the position and height of the activation barrier. Furthermore, the\nresults for the first two of these fit parameters show little dependence on the\nassumption about the manner in which the barrier decreases with the applied\nforce, while the last one, the barrier height in the absence of force, depends\nstrongly on this assumption."
    },
    {
        "anchor": "The collapse transition on superhydrophobic surfaces: We investigate the transition between the Cassie-Baxter and Wenzel states of\na slowly evaporating, micron-scale drop on a superhydrophobic surface. In two\ndimensions analytical results show that there are two collapse mechanisms. For\nlong posts the drop collapses when it is able to overcome the free energy\nbarrier presented by the hydrophobic posts. For short posts, as the drop loses\nvolume, its curvature increases allowing it to touch the surface below the\nposts. We emphasise the importance of the contact line retreating across the\nsurface as the drop becomes smaller: this often preempts the collapse. In a\nquasi-three dimensional simulation we find similar behaviour, with the\nadditional feature that the drop can de-pin from all but the peripheral posts,\nso that its base resembles an inverted bowl.",
        "positive": "Activity-driven emulsification of phase-separating binary mixtures: Systems containing active components are intrinsically out of equilibrium,\nwhile binary mixtures reach their equilibrium configuration when complete phase\nseparation is achieved. Active particles are found to stabilise non-equilibrium\nmorphologies in phase separating binary mixtures by arresting coarsening by\nexerting active pressure that competes with surface tension driving forces. For\nmoderate activities, an emulsion morphology is stabilised, where the droplet\nsize is well-defined and controlled by activity. Conversely, the ability of\nactive particles to drive phase-separated mixtures away from their equilibrium\nconfiguration is shown. A rich co-assembly behaviour is shown due to the\ncompeting energy scales involved in the system."
    },
    {
        "anchor": "Self-Elongation with Sequential Folding of a Filament of Bacterial Cells: Under hard-agar and nutrient-rich conditions, a cell of $Bacillus$ $subtilis$\ngrows as a single filament owing to the failure of cell separation after each\ngrowth and division cycle. The self-elongating filament of cells shows\nsequential folding processes, and multifold structures extend over an agar\nplate. We report that the growth process from the exponential phase to the\nstationary phase is well described by the time evolution of fractal dimensions\nof the filament configuration. We propose a method of characterizing filament\nconfigurations using a set of lengths of multifold parts of a filament. Systems\nof differential equations are introduced to describe the folding processes that\ncreate multifold structures in the early stage of the growth process. We show\nthat the fitting of experimental data to the solutions of equations is\nexcellent, and the parameters involved in our model systems are determined.,",
        "positive": "Scattering of low Reynolds number swimmers: We describe the consequences of time reversal invariance of the Stokes'\nequations for the hydrodynamic scattering of two low Reynolds number swimmers.\nFor swimmers that are related to each other by a time reversal transformation\nthis leads to the striking result that the angle between the two swimmers is\npreserved by the scattering. The result is illustrated for the particular case\nof a linked-sphere model swimmer. For more general pairs of swimmers, not\nrelated to each other by time reversal, we find hydrodynamic scattering can\nalter the angle between their trajectories by several tens of degrees. For two\nidentical contractile swimmers this can lead to the formation of a bound state."
    },
    {
        "anchor": "Mean-field description of collapsing and exploding Bose-Einstein\n  condensates: We perform numerical simulation based on the time-dependent mean-field\nGross-Pitaevskii equation to understand some aspects of a recent experiment by\nDonley et al. on the dynamics of collapsing and exploding Bose-Einstein\ncondensates of $^{85}$Rb atoms. They manipulated the atomic interaction by an\nexternal magnetic field via a Feshbach resonance, thus changing the repulsive\ncondensate into an attractive one and vice versa. In the actual experiment they\nchanged suddenly the scattering length of atomic interaction from positive to a\nlarge negative value on a pre-formed condensate in an axially symmetric trap.\nConsequently, the condensate collapses and ejects atoms via explosion. We find\nthat the present mean-field analysis can explain some aspects of the dynamics\nof the collapsing and exploding Bose-Einstein condensates.",
        "positive": "Constitutive modeling, non-linear behavior, and the stress-optic law: Constitutive modelling of the stress-strain response of rubbery polymers is\ndescribed, with an emphasis on the limits to linearity for both neat and filled\nrubber (the latter due to the Payne effect). Deviations from the Boltzmann\nsuperposition principle (time-strain invariance) under reversing strain\nhistories are reviewed, including a discussion of the Mullins effect. The\nchapter also reviews the application of the stress optic law and the conditions\ncausing its breakdown: internal stress, the glass transition, orientational\ncoupling, and creep recovery. Different empirical rules for nonlinear flow are\nconsidered, including the Cox-Merz rule and the relations of Laun and Gleissle."
    },
    {
        "anchor": "Thermodynamics of supercooled liquids in the inherent structure\n  formalism: a case study: In this article we review the thermodynamics of liquids in the framework of\nthe inherent structure formalism. We then present calculations of the\ndistribution of the basins in the potential energy of a binary Lennard-Jones\nmixture as a function of temperature. The comparison between the numerical data\nand the theoretical formalism allows us to evaluate the degeneracy of the\ninherent structures in a bulk system and to estimate the energy of the lowest\nenergy disordered state (the Kauzmann energy). We find that, around the\nmode-coupling temperature, the partition function of the liquid is approximated\nwell by the product of two loosely coupled partition functions, one depending\non the inherent structures quantities (depth of the basins and their\ndegeneracy) and one describing the free energy of the liquid constrained in one\ntypical basin.",
        "positive": "Dynamics of suspensions of hydrodynamically structured particles:\n  Analytic theory and experiment: We present an easy-to-use analytic toolbox for the calculation of short-time\ntransport properties of concentrated suspensions of spherical colloidal\nparticles with internal hydrodynamic structure, and direct interactions\ndescribed by a hard-core or soft Hertz pair potential. The considered dynamic\nproperties include self-diffusion and sedimentation coefficients, the\nwavenumber-dependent diffusion function determined in dynamic scattering\nexperiments, and the high-frequency shear viscosity. The toolbox is based on\nthe hydrodynamic radius model (HRM) wherein the internal particle structure is\nmapped on a hydrodynamic radius parameter for unchanged direct interactions,\nand on an existing simulation data base for solvent-permeable and spherical\nannulus particles. Useful scaling relations for the diffusion function and\nself-diffusion coefficient, known to be valid for hard-core interaction, are\nshown to apply also for soft pair potentials. We further discuss extensions of\nthe toolbox to long-time transport properties including the low-shear\nzero-frequency viscosity and the long-time self-diffusion coefficient. The\nversatility of the toolbox is demonstrated by the analysis of a previous light\nscattering study of suspensions of non-ionic PNiPAM microgels [Eckert et al.,\nJ. Chem. Phys., 2008, 129, 124902] in which a detailed theoretical analysis of\nthe dynamic data was left as an open task. By the comparison with Hertz\npotential based calculations, we show that the experimental data are\nconsistently and accurately described using the Verlet-Weis corrected\nPercus-Yevick structure factor as input, and for a solvent penetration length\nequal to three percent of the excluded volume radius. This small solvent\npermeability of the microgel particles has a significant dynamic effect at\nlarger concentrations."
    },
    {
        "anchor": "Smectic-C tilt under shear in Smectic-A elastomers: Stenull and Lubensky [Phys. Rev. E {\\bf 76}, 011706 (2007)] have argued that\nshear strain and tilt of the director relative to the layer normal are coupled\nin smectic elastomers and that the imposition of one necessarily leads to the\ndevelopment of the other. This means, in particular, that a Smectic-A elastomer\nsubjected to a simple shear will develop Smectic-C-like tilt of the director.\nRecently, Kramer and Finkelmann [arXiv:0708.2024, Phys. Rev. E {\\bf 78}, 021704\n(2008)] performed shear experiments on Smectic-A elastomers using two different\nshear geometries. One of the experiments, which implements simple shear,\nproduces clear evidence for the development of Smectic-C-like tilt. Here, we\ngeneralize a model for smectic elastomers introduced by Adams and Warner [Phys.\nRev. E {\\bf 71}, 021708 (2005)] and use it to study the magnitude of\nSmectic-C-like tilt under shear for the two geometries investigated by Kramer\nand Finkelmann. Using reasonable estimates of model parameters, we estimate the\ntilt angle for both geometries, and we compare our estimates to the\nexperimental results. The other shear geometry is problematic since it\nintroduces additional in-plane compressions in a sheet-like sample, thus\ninducing instabilities that we discuss.",
        "positive": "A tentative geometrical description of static dilatancy in liquid foams:\n  ordered 2D and 3D foams: Liquid foams have been observed to behave like immersed granular materials in\nat least one respect: deformation tends to raise their liquid contents, a\nphenomenon called dilatancy. We present a geometrical interpretation thereof in\nfoams squeezed between two solid plates (2D GG foams), which contain pseudo\nPlateau borders along the plates, and in 3D foams. While experimental\nobservations evidenced the effect of a continuous deformation rate (dynamic\ndilatancy), the present argument applies primarily to elastic deformation\n(static dilatancy). We show that the negative dilatancy predicted by Weaire and\nHutzler (Phil. Mag. 83 (2003) 2747) at very low liquid fractions is specific to\nideal 2D foams and should not be observed in the dry limit of real 2D foams."
    },
    {
        "anchor": "Simulations of Two-Dimensional Unbiased Polymer Translocation Using the\n  Bond Fluctuation Model: We use the Bond Fluctuation Model (BFM) to study the pore-blockade times of a\ntranslocating polymer of length $N$ in two dimensions, in the absence of\nexternal forces on the polymer (i.e., unbiased translocation) and hydrodynamic\ninteractions (i.e., the polymer is a Rouse polymer), through a narrow pore.\nEarlier studies using the BFM concluded that the pore-blockade time scales with\npolymer length as $\\tau_d \\sim N^\\beta$, with $\\beta=1+2\\nu$, whereas some\nrecent studies with different polymer models produce results consistent with\n$\\beta=2+\\nu$, originally predicted by us. Here $\\nu$ is the Flory exponent of\nthe polymer; $\\nu=0.75$ in 2D. In this paper we show that for the BFM if the\nsimulations are extended to longer polymers, the purported scaling $\\tau_d \\sim\nN^{1+2\\nu}$ ceases to hold. We characterize the finite-size effects, and study\nthe mobility of individual monomers in the BFM. In particular, we find that in\nthe BFM, in the vicinity of the pore the individual monomeric mobilities are\nheavily suppressed in the direction perpendicular to the membrane. After a\nmodification of the BFM which counters this suppression (but possibly\nintroduces other artifacts in the dynamics), the apparent exponent $\\beta$\nincreases significantly. Our conclusion is that BFM simulations do not rule out\nour theoretical prediction for unbiased translocation, namely $\\beta=2+\\nu$.",
        "positive": "Textures and shapes in nematic elastomers under the action of dopant\n  concentration gradients: We explore a novel strategy of patterning nematic elastomers that does not\nrequire inscribing the texture directly. It is based on varying the dopant\nconcentration that, beside shifting the phase transition point, affects the\nnematic director field via coupling between the gradients of concentration and\nnematic order parameter. Rotation of the director around a point dopant source\ncauses topological modification manifesting itself in a change of the number of\ndefects. A variety of shapes, dependent on the dopant distribution, are\nobtained by anisotropic deformation following the nematic--isotropic\ntransition."
    },
    {
        "anchor": "Stratification of polymer-colloid mixtures via fast nonequilibrium\n  evaporation: In drying liquid films of polymer-colloid mixtures, the stratification in\nwhich polymers are placed on top of larger colloids is studied. It is often\npresumed that the formation of segregated polymer-colloid layers is solely due\nto the proportion in size at fast evaporation as in binary colloid mixtures. By\ncomparing experiments with a theoretical model, we found that the transition in\nviscosity near the drying interface was another important parameter for\ncontrolling the formation of stratified layers in polymer-colloid mixtures. At\nhigh evaporation rates, increased polymer concentrations near the surface lead\nto a phase transition from semidilute to concentrated regime, in which\ncolloidal particles are kinetically arrested. Stratification only occurs if the\nformation of a stratified layer precedes the evolution to the concentrated\nregime near the drying interfaces. Otherwise, the colloids will be trapped by\nthe polymers in the concentrated regime before forming a segregated layer.\nAlso, no stratification is observed if the initial polymer concentration is too\nlow to form a sufficiently high polymer concentration gradient within a short\nperiod of time. Our findings are relevant for developing solution-cast polymer\ncomposite for painting, antifouling and antireflective coatings.",
        "positive": "Molecular Dynamics Study of Conformations of Beta-Cyclodextrin and its\n  Eight Derivatives in Four Different Solvents: Understanding the atomic level interactions and the resulting structural\ncharacteristics is required for developing beta-cyclodextrin ($\\beta$CD)\nderivatives for pharmaceutical and other applications. The effect of four\ndifferent solvents on the structures of the native $\\beta$CD and its\nhydrophilic (methylated $\\beta$CD; ME$\\beta$CD and hydroxypropyl $\\beta$CD;\nHP$\\beta$CD) and hydrophobic derivatives (ethylated $\\beta$CD; ET$\\beta$CD)\nwere explored using molecular dynamics (MD) simulations and solvation free\nenergy calculations. The native $\\beta$CD, 2-ME$\\beta$CD, 6-ME$\\beta$CD,\n2,6-DM$\\beta$CD, 2,3,6-TM$\\beta$CD, 6-HP$\\beta$CD, 2,6-HP$\\beta$CD and\n2,6-ET$\\beta$CD in non-polar solvents (cyclohexane; CHX and octane; OCT) were\nstably formed in symmetric cyclic cavity shape through their intramolecular\nhydrogen bonds. In contrast, $\\beta$CDs in polar solvents (methanol; MeOH and\nwater; WAT) exhibited large structural changes and fluctuations leading to\nsignificant deformations of their cavities. Hydrogen bonding with polar\nsolvents was found to be one of the major contributors to this behavior:\nsolvent-\\b{eta}CD hydrogen bonding strongly competes with intramolecular\nbonding leading to significant changes in structural stability of $\\beta$CDs.\nThe exception to this is the hydrophobic 2,6-ET$\\beta$CD which retained its\nspherical cavity in all solvents. Based on this, it is proposed that\n2,6-ET$\\beta$CD can act as a sustained release drug carrier."
    },
    {
        "anchor": "Dichotomous behaviors of stress and dielectric relaxations in dense\n  suspensions of swollen thermoreversible hydrogel microparticles: Hypothesis: While the mechanical disruption of microscopic structures in\ncomplex fluids by large shear flows has been studied extensively, the effects\nof applied strains on the dielectric properties of macromolecular aggregates\nhas received far less attention. Simultaneous rheology and dielectric\nexperiments can be employed to study the dynamics of sheared colloidal\nsuspensions over spatiotemporal scales spanning several decades.\n  Experiments: Using a precision impedance analyzer, we study the dielectric\nbehavior of strongly sheared aqueous suspensions of thermoreversible hydrogel\npoly(N-isopropylacrylamide) (PNIPAM) particles at different temperatures. We\nalso perform stress relaxation experiments to uncover the influence of large\ndeformations on the bulk mechanical moduli of these suspensions.\n  Findings: The real parts of the complex dielectric permittivities of all the\nsheared PNIPAM suspensions exhibit distinct relaxation processes in the low and\nhigh frequency regimes. At a temperature below the lower consolute solution\ntemperature (LCST), both real and imaginary parts of the permittivities of\nhighly dense PNIPAM suspensions decrease with increase in applied oscillatory\nstrain amplitudes. Simultaneously, we note a counter-intuitive slowdown of the\ndielectric relaxation dynamics. Contrary to our rheo-dielectric findings, our\nbulk rheology experiments, performed under identical conditions, reveal\nshear-thinning dynamics with increasing strain amplitudes. We propose the\nshear-induced rupture of fragile clusters of swollen PNIPAM particles to\nexplain our observations.\n  Keywords : Rheo-dielectric; Thermoresponsive hydrogels; Segmental motion;\nCounterion polarization; Interfacial polarization; Dense suspensions; Rheology;\nShear-thinning.",
        "positive": "Modelling Polymer Self Diffusion: An Alternative Model to Reptation: Herein an alternative model to reptation to describe concentrated polymer\ndynamics is developed. The model assumes that the chains act as blobs that are\nable to diffuse past each other in a compressed state. Allowing that the local\nviscosity experienced by a blob is less than the macroscopic viscosity allows\nthe viscosity-molecular weight and diffusion coefficient-molecular weight\nrelationships to be determined."
    },
    {
        "anchor": "Bending rigidities and interdomain forces in membranes with coexisting\n  lipid domains: In order to precisely quantify the fundamental interactions between\nheterogeneous lipid membranes with coexisting liquid-ordered (Lo) and\nliquid-disordered (Ld) domains, we performed detailed osmotic stress SAXS\nexperiments by exploiting the domain alignment in raft-mimicking lipid\nmultibilayers. Performing a Monte Carlo (MC) based analysis allowed us to\ndetermine with high reliability the magnitude and functional dependence of\ninterdomain forces concurrently with the bending elasticity moduli. In contrast\nto previous methodologies, this approach enabled us to consider the entropic\nundulation repulsions on a fundamental level, without having to take recourse\nto crudely justified mean-field like additivity assumptions. Our detailed\nHamaker coefficient calculations indicated only small differences in the van\nder Waals attractions of coexisting Lo and Ld phases. In contrast, the\nrepulsive hydration and undulation interactions differed significantly, with\nthe latter dominating the overall repulsions in the Ld phase. Therefore,\nalignment of like domains in multibilayers appears to originate from both,\nhydration and undulation repulsions.",
        "positive": "Statistical Physics of the Yielding Transition in Amorphous Solids: The art of making structural, polymeric and metallic glasses is rapidly\ndeveloping with many applications. A limitation to their use is their\nmechanical stability: under increasing external strain all amorphous solids\nrespond elastically to small strains but have a finite yield stress which\ncannot be exceeded without effecting a plastic response which typically leads\nto mechanical failure. Understanding this is crucial for assessing the risk of\nfailure of glassy materials under mechanical loads. Here we show that the\nstatistics of the energy barriers \\Delta E that need to be surmounted changes\nfrom a probability distribution function (pdf) that goes smoothly to zero to a\npdf which is finite at \\Delta E=0. This fundamental change implies a dramatic\ntransition in the mechanical stability properties with respect to external\nstrain. We derive exact results for the scaling exponents that characterize the\nmagnitudes of average energy and stress drops in plastic events as a function\nof system size."
    },
    {
        "anchor": "Polysaccharide/Surfactant complexes at the air-water interface - Effect\n  of the charge density on interfacial and foaming behaviors: The binding of a cationic surfactant (hexadecyltrimethylammonium bromide,\nCTAB) to a negatively charged natural polysaccharide (pectin) at air-solution\ninterfaces, was investigated on single interfaces and in foams, versus the\nlinear charge densities of the polysaccharide. Beside classical methods to\ninvestigate polymer/surfactant systems, we applied, for the first time\nconcerning these systems, the analogy between the small angle neutron\nscattering by foams and the neutron reflectivity of films to measure in situ\nfilm thicknesses of foams. CTAB/pectin foam films are much thicker than that of\nthe pure surfactant foam film but similar for highly and lowly charged\npectin/CTAB systems despite the difference in structure of complexes at\ninterfaces. The improvement of the foam properties of CTAB bound to pectin is\nshown to be directly related to the formation of pectin-CTAB complexes at the\nair-water interface. However, in opposition to surface activity, there is no\nspecific behavior for the highly charged pectin: foam properties depend mainly\nupon the bulk charge concentration, while the interfacial behavior is mainly\ngoverned by the charge density of pectin. For the highly charged pectin,\nspecific cooperative effects between neighboring charged sites along the chain\nare thought to be involved in the higher surface activity of pectin/CTAB\ncomplexes. A more general behavior can be obtained at lower charge density\neither by using a lowly charged pectin or by neutralizing the highly charged\npectin in decreasing pH. .",
        "positive": "Phase Behavior of Block Copolymer Nanocomposite Systems: Nanocomposite materials made of block copolymer and nanoparticles display\nproperties which can be different from the purely polymeric matrix. The\nresulting material is a crossover of the original properties of the block\ncopolymer and the presence of the assembled nanoparticles. We propose a\nmesoscopic study via cell dynamic simulations to quantitatively assert the\nproperties of such hybrid materials. The most relevant parameters are\nidentified to be the fraction of nanoparticles in the system and its chemical\naffinity, while the nanoparticle size with respect to the block copolymer\nlength scales plays a role in the assembly. The morphological phase diagram of\nthe block copolymer is constructed for nanoparticles with chemical affinity\nranging from A-compatible to B-compatible for a symmetric A-B diblock\ncopolymer. Block-compatible nanoparticles is found to induce a phase transition\ndue to changes in the effective concentration of the hosting phase, while\ninterface-compatible particles induces the appearance of two new phases due to\nthe saturation of the diblock copolymer interface."
    },
    {
        "anchor": "Enhancing Composition Window of Bicontinuous Structures by Designed\n  Polydispersity Distribution of ABA Triblock Copolymers: The phase behavior of polydisperse ABA triblock copolymers is studied using\ndissipative particle dynamics simulations, focusing on the emergence and\nproperty of bicontinuous structures. Bicontinuous structures are characterized\nby two separate, intermeshed nanoscopic domains extending throughout the\nmaterial. The connectivity of polymeric bicontinuous structures makes them\nhighly desirable for many applications. For conventional monodisperse diblock\nand triblock copolymers, regular bicontinuous structures (i.e., gyroid and\nFddd) can be formed over a narrow composition window of ~3%. We demonstrate\nthat the composition window for the formation of bicontinuous structures can be\nregulated by designed polydispersity distributions of ABA triblock copolymers.\nIn particular, introducing polydispersity in both A and B blocks can lead to a\nsignificant enhancement of the composition window of bicontinuous structures\nwith both continuous A and B domains. The mechanism of the bicontinuous\nstructure enhancement is elucidated from the distribution of the long and short\nblocks. Furthermore, it is shown that the polymeric bicontinuous structures\nfrom polydisperse ABA triblock copolymers possess good continuity throughout\nthe sample, making them ideal candidates for advanced applications.",
        "positive": "Stretching of a single-stranded DNA: Evidence for structural transition: Recent experiments have shown that the force-extension (F-x) curve for\nsingle-stranded DNA (ssDNA) consisting only of adenine [poly(dA)] is\nsignificantly different from thymine [poly(dT)]. Here, we show that the base\nstacking interaction is not sufficient to describe the F-x curves as seen in\nthe experiments. A reduction in the reaction co-ordinate arising from the\nformation of helix at low forces and an increase in the distance between\nconsecutive phosphates of unstacked bases in the stretched state at high force\nin the proposed model, qualitatively reproduces the experimentally observed\nfeatures. The multi-step plateau in the F-x curve is a signature of structural\nchange in ssDNA."
    },
    {
        "anchor": "Symmetrization of Thin Free-Standing Liquid Films via Capillary-Driven\n  Flow: We present experiments to study the relaxation of a nano-scale cylindrical\nperturbation at one of the two interfaces of a thin viscous free-standing\npolymeric film. Driven by capillarity, the film flows and evolves towards\nequilibrium by first symmetrizing the perturbation between the two interfaces,\nand eventually broadening the perturbation. A full-Stokes hydrodynamic model is\npresented which accounts for both the vertical and lateral flows, and which\nhighlights the symmetry in the system. The symmetrization time is found to\ndepend on the membrane thickness, surface tension, and viscosity.",
        "positive": "Elastic impact of a sphere with an elastic half-space: numerical\n  modeling and comparison with experiment: Numerical simulations of the dynamics of an elastic collision between a rigid\nsphere and an elastic half-space are carried out. We assume an Amontons-Coulomb\nfrictional force with a fixed coefficient of friction between the contacting\nsurfaces during the impact. As a result of modeling a dimensionless function,\ndescribing the tangential restitution, is found. It depends only on a small set\nof governing dimensionless parameters and allows the determination of the\nsphere's tangential velocity and angular velocity after the collision. This\nfunction is used to calculate the tangential velocity recovery rate and the\ncyclic rotation frequency of a sphere for the parameters of a particular\nexperiment on particle reflection of an aluminum alloy from a glass plate. The\nobtained results with high accuracy coincide with the experimental data, which\nconfirms the adequacy of the proposed numerical model."
    },
    {
        "anchor": "Slight compressibility and sensitivity to changes in Poisson's ratio: Finite Element simulations of rubbers and biological soft tissue usually\nassume that the material being deformed is slightly compressible. It is shown\nhere that in shearing deformations the corresponding normal stress distribution\ncan exhibit extreme sensitivity to changes in Poisson's ratio. These changes\ncan even lead to a reversal of the usual Poynting effect. Therefore the usual\npractice of arbitrarily choosing a value of Poisson's ratio when numerically\nmodelling rubbers and soft tissue will, almost certainly, lead to a significant\ndifference between the simulated and actual normal stresses in a sheared block\nbecause of the difference between the assumed and actual value of Poisson's\nratio. The worrying conclusion is that simulations based on arbitrarily\nspecifying Poisson's ratio close to 1/2 cannot accurately predict the normal\nstress distribution even for the simplest of shearing deformations. It is shown\nanalytically that this sensitivity is due to the small volume changes which\ninevitably accompany all deformations of rubber-like materials. To minimise\nthese effects, great care should be exercised to accurately determine Poisson's\nratio before simulations begin.",
        "positive": "Measuring surface charge: why experimental characterization and\n  molecular modeling should be coupled: Surface charge controls many static and dynamic properties of soft matter and\nmicro/nanofluidic systems, but its unambiguous measurement forms a challenge.\nStandard characterization methods typically probe an effective surface charge,\nwhich provides limited insight into the distribution and dynamics of charge\nacross the interface, and which cannot predict consistently all\nsurface-charge-governed properties. New experimental approaches provide local\ninformation on both structure and transport, but models are typically required\nto interpret raw data. Conversely, molecular dynamics simulations have helped\nshowing the limits of standard models and developing more accurate ones, but\ntheir reliability is limited by the empirical interaction potentials they are\nusually based on. This review highlights recent developments and limitations in\nboth experimental and computational research focusing on the liquid-solid\ninterface. Based on recent studies, we make the case that coupling of\nexperiments and simulations is pivotal tomitigate methodological shortcomings\nand address open problems pertaining to charged interfaces."
    },
    {
        "anchor": "Jamming phase diagram of athermal emulsions with short-range attraction: Using confocal microscopy we investigate the effect of attraction on the\npacking of polydisperse emulsions under gravity. We find that the distributions\nof neighbors, coordination number, and local packing fraction as a function of\nattraction are captured by recently proposed geometrical modeling and\nstatistical mechanics approaches to granular matter. This extends the range of\napplicability of these tools to polydisperse, attractive jammed packings.\nFurthermore, the dependence of packing density and average coordination number\non the strength of attraction provides the first experimental test of a phase\ndiagram of athermal jammed particles. The success of these theoretical\nframeworks in describing a new class of systems gives support to the\nmuch-debated statistical physics of jammed matter.",
        "positive": "Role of roughness on the hydrodynamic homogeneous base state of\n  inelastic spheres: A gas of inelastic rough spheres admits a spatially homogeneous base state\nwhich turns into a hydrodynamic state after a finite relaxation time. We show\nthat this relaxation time is hardly dependent on the degree of inelasticity but\nincreases dramatically with decreasing roughness. An accurate description of\ntranslational-rotational velocity correlations at all times is also provided.\nAt a given inelasticity, the roughness parameter can be tuned to produce a huge\ndistortion from the Maxwellian distribution function. The results are obtained\nfrom a Grad-like solution of the Boltzmann-Enskog equation complemented by\nMonte Carlo and molecular dynamics simulations."
    },
    {
        "anchor": "Viral air load due to sedimenting and evaporating droplets produced by\n  speaking: The effect of evaporation on droplet sedimentation times is crucial for\nestimating the risk of infection from virus-containing airborne droplets. For\ndroplet radii in the range 100 nm < R < 60 {\\mu}m, evaporation can be described\nin the stagnant-flow approximation and is diffusion limited. Analytical\nequations are presented for the droplet evaporation rate, the time-dependent\ndroplet size and the sedimentation time, including the significant effect of\nevaporation cooling. Evaporation makes the time for large droplets to sediment\nmuch longer and thus significantly increases the viral air load. Using recent\nestimates for SARS-CoV-2 concentrations in sputum and droplet production rates\nwhile speaking, a single infected person that constantly speaks without a mouth\ncover produces a total air load of more than 10^4 virions. In a mid-size closed\nroom, this leads to a viral inhalation frequency of at least 2.5 per minute.\nLow relative humidity, as encountered inside buildings in winter and in\nairliners, speeds evaporation and thus keeps initially larger droplets\nsuspended in air.",
        "positive": "Nanoconfined Polystyrene: A New Phase: Transverse layering of molecular gyration spheres in spin-coated atactic\npolystyrene ($aPS$) films, for film thickness $R \\leq$ 4$R_g$ ($R_g$ =\nunperturbed gyration radius), causes an increase in free energy that does not\nfollow the $(R_g/R)^{-2}$ dependence of planar confinement and is explained by\ninvoking a fixed-range, repulsive, modified P\\\"{o}schl-Teller intermolecular\npotential, its strength decreasing with increase in $R$. Vacuum ultraviolet\nspectroscopy reveals a change in 'physical dimers' of adjacent pendant benzene\nrings of $aPS$ from 'oblique' to 'head-to-tail' configuration as film thickness\ngoes from 9$R_{g}$ to 2$R_{g}$. This reduces cohesion by reducing dimer dipole\nmoment. Thus a new phase of $aPS$, the nanoconfined phase, ordered but with\nlower cohesion than bulk, is formed."
    },
    {
        "anchor": "Hydrodynamics of bacterial motion: In this paper we present a hydrodynamic approach to describe the motion of\nmigrating bacteria as a special class of self-propelled systems. Analytical and\nnumerical calculations has been performed to study the behavior of our model in\nthe turbulent-like regime and to show that a phase transition occurs as a\nfunction of noise strength. Our results can explain previous experimental\nobservations as well as results of numerical simulations.",
        "positive": "Dipolar interactions induced order in assemblies of magnetic particles: We discuss the appareance of ordered structures in assemblies of magnetic\nparticles. The phenomenon occurs when dipolar interactions and the thermal\nmotion of the particles compete, and is mediated by screening and excluded\nvolume effects. It is observed irrespective of the dimensionality of the system\nand the resulting structures, which may be regular or fractal, indicate that\nnew ordered phases may emerge in these system when dipolar interactions play a\nsignificant role."
    },
    {
        "anchor": "Rain: Relaxations in the sky: We demonstrate how, from the point of view of energy flow through an open\nsystem, rain is analogous to many other relaxational processes in Nature such\nas earthquakes. By identifying rain events as the basic entities of the\nphenomenon, we show that the number density of rain events per year is\ninversely proportional to the released water column raised to the power 1.4.\nThis is the rain-equivalent of the Gutenberg-Richter law for earthquakes. The\nevent durations and the waiting times between events are also characterised by\nscaling regions, where no typical time scale exists. The Hurst exponent of the\nrain intensity signal $H = 0.76 > 0.5$. It is valid in the temporal range from\nminutes up to the full duration of the signal of half a year. All of our\nfindings are consistent with the concept of self-organised criticality, which\nrefers to the tendency of slowly driven non-equilibrium systems towards a state\nof scale free behaviour.",
        "positive": "Slip, immiscibility and boundary conditions at the liquid-liquid\n  interface: The conventional boundary conditions at the interface between two flowing\nliquids include continuity of the tangential velocity. We have tested this\nassumption with molecular dynamics simulations of Couette and Poiseuille flows\nof two-layered liquid systems, with various molecular structures and\ninteractions. When the total liquid density near the interface drops\nsignificantly compared to the bulk values, the tangential velocity varies very\nrapidly there, and would appear discontinuous at continuum resolution. The\nvalue of this apparent slip is given by a Navier boundary condition."
    },
    {
        "anchor": "Fluid of fused spheres as a model for protein solution: In this work we examine thermodynamics of fluid with \"molecules\" represented\nby two fused hard spheres, decorated by the attractive square-well sites.\nInteractions between these sites are of short-range and cause association\nbetween the fused-sphere particles. The model can be used to study the\nnon-spherical (or dimerized) proteins in solution. Thermodynamic quantities of\nthe system are calculated using a modification of Wertheim's thermodynamic\nperturbation theory and the results compared with new Monte Carlo simulations\nunder isobaric-isothermal conditions. In particular, we are interested in the\nliquid-liquid phase separation in such systems. The model fluid serves to\nevaluate the effect of the shape of the molecules, changing from spherical to\nmore elongated (two fused spheres) ones. The results indicate that the effect\nof the non-spherical shape is to reduce the critical density and temperature.\nThis finding is consistent with experimental observations for the antibodies of\nnon-spherical shape.",
        "positive": "Effective Interaction of Charged Platelets in Aqueous Solution:\n  Investigations of Colloid Laponite Suspensions by Static Light Scattering and\n  Small-Angle X-Ray Scattering: We study dilute aqueous solutions of charged disk-like mineral particles\n(Laponite) by a combination of static light scattering (SLS) and small-angle\nx-ray scattering (SAXS). Laponite solutions are known to form gels above a\ncertain critical concentration that must be described as non-equilibrium\nstates. Here we focus on the investigation by SLS and SAXS at concentrations\nbelow gelation (c < 0.016 g/L) and at low concentrations of added salt (0.001\nand 0.005 mM). Thus, we have obtained the scattering function of single\nLaponite platelets as well as the structure factor describing their interaction\nat finite concentration. A detailed analysis of the combined sets of data\nproves that the solutions are in a well-defined equilibrium state. Moreover,\nthis analysis demonstrates the internal consistency and accuracy of the\nscattering functions obtained at finite concentrations. We find that Laponite\nparticles interact through an effective pair potential that is attractive on\nshort range but repulsive on longer range. This finding demonstrates that\nLaponite solutions exhibit only a limited stability at the concentration of\nadded salt used herein. Raising the ionic strength to 0.005 mM already leads to\nslow flocculation as is evidenced from the enhanced scattering intensity at\nsmallest scattering angles. All data strongly suggest that the gelation\noccurring at higher concentration is related to aggregation."
    },
    {
        "anchor": "Strongly nonlinear waves in a chain of Teflon beads: One dimensional \"sonic vacuum\" type phononic crystals were assembled from a\nchain of Teflon spheres with different diameters in a Teflon holder. It was\ndemonstrated for the first time that this polymer-based \"sonic vacuum\", with\nexceptionally low elastic modulus of particles, supports propagation of\nstrongly nonlinear solitary waves with a very low speed.",
        "positive": "The Dynamic Transition of Protein Hydration Water: Thin layers of water on biomolecular and other nanostructured surfaces can be\nsupercooled to temperatures not accessible with bulk water. Chen et al. [PNAS\n103, 9012 (2006)] suggested that anomalies near 220 K observed by quasi-elastic\nneutron scattering can be explained by a hidden critical point of bulk water.\nBased on more sensitive measurements of water on perdeuterated phycocyanin,\nusing the new neutron backscattering spectrometer SPHERES, and an improved data\nanalysis, we present results that show no sign of such a fragile-to-strong\ntransition. The inflection of the elastic intensity at 220 K has a dynamic\norigin that is compatible with a calorimetric glass transition at 170 K. The\ntemperature dependence of the relaxation times is highly sensitive to data\nevaluation; it can be brought into perfect agreement with the results of other\ntechniques, without any anomaly."
    },
    {
        "anchor": "Ideal isotropic auxetic networks from random networks: Auxetic materials are characterized by a negative Poisson's ratio,\n$\\mathrm{\\nu}$. As the Poisson's ratio becomes negative and approaches the\nlower isotropic mechanical limit of $\\mathrm{\\nu = -1}$, materials show\nenhanced resistance to impact and shear, making them suitable for applications\nranging from robotics to impact mitigation. Past experimental efforts aimed at\nreaching the $\\mathrm{\\nu = -1}$ limit have resulted in highly anisotropic\nmaterials, which show a negative Poisson's ratio only when subjected to\ndeformations along specific directions. Isotropic designs have only attained\nmoderately auxetic behavior, or have led to structures that cannot be\nmanufactured in 3D. Here, we present a design strategy to create isotropic\nstructures from disordered networks that leads to Poisson's ratios as low as\n$\\mathrm{\\nu = -0.98}$. The materials conceived through this approach are\nsuccessfully fabricated in the laboratory and behave as predicted. The\nPoisson's ratio $\\mathrm{\\nu}$ is found to depend on network structure and bond\nstrengths; this sheds light on the structural motifs that lead to auxetic\nbehavior. The ideas introduced here can be generalized to 3D, a wide range of\nmaterials, and a spectrum of length scales, thereby providing a general\nplatform that could impact technology.",
        "positive": "Role of friction in multidefect ordering: We use continuum simulations to study the impact of friction on the ordering\nof defects in an active nematic. Even in a frictionless system, +1/2 defects\ntend to align side-by-side and orient antiparallel reflecting their propensity\nto form, and circulate with, flow vortices. Increasing friction enhances the\neffectiveness of the defect-defect interactions, and defects form dynamically\nevolving, large scale, positionally and orientationally-ordered structures\nwhich can be explained as a competition between hexagonal packing, preferred by\nthe -1/2 defects, and rectangular packing preferred by the +1/2 defects."
    },
    {
        "anchor": "Thermodynamics and kinetics of vapor bubbles nucleation in one-component\n  liquids: The multivariable theory of nucleation [J. Chem. Phys. 124, 124512 (2006)] is\napplied to the problem of vapor bubbles formation in pure liquids. The\npresented self-consistent macroscopic theory of this process employs\nthermodynamics (classical, statistical and linear non-equilibrium),\nhydrodynamics and interfacial kinetics. As a result of thermodynamic study of\nthe problem, the work of formation of a bubble is obtained and parameters of\nthe critical bubble are determined. The variables V (the bubble volume), \\rho\n(the vapor density), and T (the vapor temperature) are shown to be natural for\nthe given task. An algorithm of writing the equations of motion of a bubble in\nthe space {V, \\rho, T} - equations for V, \\rho, and T - is offered. This\nalgorithm ensures symmetry of the matrix of kinetic coefficients. The equation\nfor written on the basis of this algorithm is shown to represent the first law\nof thermodynamics for a bubble. The negative eigenvalue of the motion equations\nwhich alongside with the work of the critical bubble formation determines the\nstationary nucleation rate of bubbles is obtained. Various kinetic limits are\nconsidered. One of the kinetic constraints leads to the fact that the\nnucleation cannot occur in the whole metastable region; it occurs only in some\nsubregion of the latter. Zeldovich theory of cavitation is shown to be a\nlimiting case of the theory presented. The limiting effects of various kinetic\nprocesses on the nucleation rate of bubbles are shown analytically. These are\nthe inertial motion of a liquid as well as the processes of particles exchange\nand heat exchange between a bubble and surrounding liquid. The nucleation rate\nis shown to be determined by the slowest kinetic process at positive and\nmoderately negative pressures in a liquid. The limiting effect vanishes at high\nnegative pressures.",
        "positive": "Combined neutron reflectometry and rheology: We have combined neutron reflectometry with rheology in order to investigate\nthe solid boundary of liquids and polymers under shear deformation. Our\napproach allows one to apply a controlled stress to a material while resolving\nthe structural arrangements on the sub nanometer length scale with neutron\nreflectivity, off-specular and small angle scattering at the same time. The\nspecularly reflected neutron intensity of a 20 % by weight solution of the\nPluronic F127 in deuterated water is evaluated. We find pronounced changes in\nthe near interface structure under applied deformation for surfaces with\ndifferent surface energies, which are correlated with changes in the storage\nand loss modulus."
    },
    {
        "anchor": "Computer simulation study of the nematic-vapour interface in the\n  Gay-Berne model: We present computer simulations of the vapour-nematic interface of the\nGay-Berne model. We considered situations which correspond to either prolate or\noblate molecules. We determine the anchoring of the nematic phase and correlate\nit with the intermolecular potential parameters. On the other hand, we evaluate\nthe surface tension associated to this interface. We find a corresponding\nstates law for the surface tension dependence on the temperature, valid for\nboth prolate and oblate molecules.",
        "positive": "Odd Viscosity and Odd Elasticity: Elasticity typically refers to a material's ability to store energy, while\nviscosity refers to a material's tendency to dissipate it. In this review, we\ndiscuss fluids and solids for which this is not the case. These materials\ndisplay additional linear response coefficients known as odd viscosity and odd\nelasticity. We first introduce odd elasticity and odd viscosity from a\ncontinuum perspective, with an emphasis on their rich phenomenology, including\ntransverse responses, modified dislocation dynamics, and topological waves. We\nthen provide an overview of systems that display odd viscosity and odd\nelasticity. These systems range from quantum fluids, to astrophysical gasses,\nto active and driven matter. Finally, we comment on microscopic mechanisms by\nwhich odd elasticity and odd viscosity arise."
    },
    {
        "anchor": "Shape- and orientation-dependent diffusiophoresis of colloidal\n  ellipsoids: We present the diffusiophoresis of ellipsoidal particles induced by ionic\nsolute gradients. Contrary to the common expectation that diffusiophoresis is\nshape independent, here we show experimentally that this assumption breaks down\nwhen the thin Debye layer approximation is relaxed. By tracking the translation\nand rotation of various ellipsoids, we find that the phoretic mobility of\nellipsoids is sensitive to the eccentricity and the orientation of the\nellipsoid relative to the imposed solute gradient, and can further lead to\nnonmonotonic behavior under strong confinement. We show that such a shape- and\norientation-dependent diffusiophoresis of colloidal ellipsoids can be easily\ncaptured by modifying theories for spheres.",
        "positive": "Mechanics of a granular skin: Magic Sand, a hydrophobic toy granular material, is widely used in popular\nscience instructions because of its non-intuitive mechanical properties. A\ndetailed study of the failure of an underwater column of magic sand shows that\nthese properties can be traced to a single phenomenon: the system\nself-generates a cohesive skin that encapsulates the material inside. The skin,\nconsists of pinned air-water-grain interfaces, shows multi-scale mechanical\nproperties: they range from contact-line dynamics in the intra-grain roughness\nscale, plastic flow at the grain scale, all the way to the sample-scale\nmechanical responses. With decreasing rigidity of the skin, the failure mode\ntransforms from brittle to ductile (both of which are collective in nature) to\na complete disintegration at the single grain scale."
    },
    {
        "anchor": "Structural and dynamical properties of a quasi-one-dimensional classical\n  binary system: The ground state configurations and the \\lq{}\\lq{}normal\\rq{}\\rq{} mode\nspectra of a $quasi$-one-dimensional (Q1D) binary system of charged particles\ninteracting through a screened Coulomb potential are presented. The minimum\nenergy configurations were obtained analytically and independently through\nmolecular dynamic simulations. A rich variety of ordered structures were found\nas a function of the screening parameter, the particle density, and the ratio\nbetween the charges of the distinct types of particles. Continuous and\ndiscontinuous structural transitions, as well as an unexpected symmetry\nbreaking in the charge distribution are observed when the density of the system\nis changed. For near equal charges we found a disordered phase where a mixing\nof the two types of particles occurs. The phonon dispersion curves were\ncalculated within the harmonic approximation for the one- and two-chain\nstructures.",
        "positive": "Entropic Trapping of Particles at Polymer Surfaces and Interfaces: I consider the possibility that Gaussian random walk statistics are\nsufficient to trap nanoscopic additives at either a polymer interface or\nsurface. When an additive particle goes to the free surface, two portions of\nthe polymer surface energy behave quite differently. The purely enthalpic\ncontribution increases the overall free energy when the additive protrudes\nabove the level of the polymer matrix. The entropic part of the surface energy\narising from constraints that segments near a surface can't cross it, is partly\nrelaxed when the additive moves to the free surface. These two portions of the\npolymer surface energy determine the equilibrium wetting angle formed between\nthe additive and the polymer matrix, the measurement of which in an experiment\nwould allow an independent determination of each piece of the polymer surface\nenergy."
    },
    {
        "anchor": "Effect of total and pair configurational entropy in determining dynamics\n  of supercooled liquids over a range of densities: In this paper, we present a study of supercooled liquids interacting with the\nLennard Jones (LJ) potential and the corresponding purely repulsive\n(Weeks-Chandler-Andersen or WCA) potential, over a range of densities and\ntemperatures, in order to understand the origin of their different dynamics in\nspite of their structures being similar. Using the configurational entropy as\nthe thermodynamic marker via the Adam Gibbs (AG) relation, we show that the\ndifference in the dynamics of these two systems at low temperatures can be\nexplained from thermodynamics. At higher densities both the thermodynamical and\ndynamical difference between these model systems decrease, which is\nquantitatively demonstrated in this paper by calculating different parameters.\nThe study also reveals the origin of the difference in pair entropy despite the\nsimilarity in the structure. Although the maximum difference in structure is\nobtained in the partial radial distribution function (rdf) of the B type of\nparticles, the rdf of AA pairs and AB pairs give rise to the differences in the\nentropy and dynamics. This work supports the observation made in an earlier\nstudy (Phys. Rev. Lett.,\\textbf {113}, 225701, 2014) and shows that they are\ngeneric in nature, independent of density.",
        "positive": "Polymers in a vacuum: In a variety of situations, isolated polymer molecules are found in a vacuum\nand here we examine their properties. Angular momentum conservation is shown to\nsignificantly alter the average size of a chain and its conservation is only\nbroken slowly by thermal radiation. The time autocorrelation for monomer\nposition oscillates with a characteristic time proportional to chain length.\nThe oscillations and damping are analyzed in detail. Short range repulsive\ninteractions suppress oscillations and speed up relaxation but stretched chains\nstill show damped oscillatory time correlations."
    },
    {
        "anchor": "Investigating the multidimensional separation behavior of particles in a\n  cyclosizer setting -- A case study on calcite, fluorite and magnesite: Particle separation is typically investigated regarding one particulate\nproperty only. Virtually all separation processes, however, act on various\nparticle properties in different ways. Modern particle analytical modalities\nenable a statistically meaningful multidimensional particle characterization.\nWithin this study, individual particle fractions of magnesite, calcite and\nfluorite (-71 $\\mu m$) are processed via the turbulent cross-flow separator\ncascade Cyclosizer (M16, MARC Technologies Pty Ltd), consisting of 5\nhydrocyclones, thus producing 5 different product streams. Particle\ncharacterization is achieved via dynamic image analysis from which information\non the particle shape and size is obtained. Using this data, bivariate Tromp\nfunctions are computed, which show the combined effect of the particle\ndescriptors of roundness and area-equivalent diameter on the separation\nbehavior. While the first cyclones recover predominantly coarse particles with\nhigh roundness values, fine particles with varying roundness are recovered in\nthe latter cyclones.",
        "positive": "Learning locally dominant force balances in active particle systems: We use a combination of unsupervised clustering and sparsity-promoting\ninference algorithms to learn locally dominant force balances that explain\nmacroscopic pattern formation in self-organized active particle systems. The\nself-organized emergence of macroscopic patterns from microscopic interactions\nbetween self-propelled particles can be widely observed nature. Although\nhydrodynamic theories help us better understand the physical basis of this\nphenomenon, identifying a sufficient set of local interactions that shape,\nregulate, and sustain self-organized structures in active particle systems\nremains challenging. We investigate a classic hydrodynamic model of\nself-propelled particles that produces a wide variety of patterns, like asters\nand moving density bands. Our data-driven analysis shows that propagating bands\nare formed by local alignment interactions driven by density gradients, while\nsteady-state asters are shaped by a mechanism of splay-induced negative\ncompressibility arising from strong particle interactions. Our method also\nreveals analogous physical principles of pattern formation in a system where\nthe speed of the particle is influenced by local density. This demonstrates the\nability of our method to reveal physical commonalities across models. The\nphysical mechanisms inferred from the data are in excellent agreement with\nanalytical scaling arguments and experimental observations."
    },
    {
        "anchor": "Details of soft particle clogging in two-dimensional hoppers: We study the outflow of soft particles through quasi-two-dimensional hoppers\nwith both experiments and simulations. The experiments utilize spheres made\nwith soft hydrogel, silicon rubber and glass. The hopper chamber has an\nadjustable exit width and tilt angle (the latter to control the magnitude of\ngravitational forcing). Our simulation mimics the experiments using purely\ntwo-dimensional soft particles with viscous interactions but no friction.\nResults from both simulations and experiments demonstrate that clogging is\neasier for reduced gravitational force or stiffer particles. For particles with\nlow or no friction, the average number of particles in a clogging arch depends\nonly on the ratio between hopper exit width and particle's diameter. In\ncontrast for the silicon rubber particles with larger frictional interactions,\narches are larger than the low friction case. Additionally, an analysis of the\nnumber of particles left in the hopper when clogging occurs provides evidence\nfor a hydrostatic pressure effect that is relevant for the clogging of soft\nparticles, but less so for the harder (glass) or frictional (silicon rubber)\nparticles.",
        "positive": "Active Materials: Biological Benchmarks and Transport Limitations: These lecture notes were prepared for the 2018 Summer School on `Active\nMatter and Non-equilibrium Statistical Physics' at l'\\'{E}cole de Physique des\nHouches. They survey metabolic activity across a wide range of living\norganisms, and consider size limitations due to the transport of fuel, waste,\nand heat for active materials at biomimetic levels of activity."
    },
    {
        "anchor": "Pinching Dynamics of Thin Films of Binary Mixtures: In binary mixtures, the lifetimes of surface bubbles can be five orders of\nmagnitude longer than those in pure liquids because of slightly different\ncompositions of the bulk and the surfaces, leading to a thickness-dependent\nsurface tension of thin films. Taking profit of the resulting simple surface\nrheology, we derive the equations describing the thickness, flow velocity and\nsurface tension of a single liquid film. Numerical resolution shows that, after\na first step of tension equilibration, a parabolic flow with mobile interfaces\nis associated with film pinching in a further drainage step. Our model paves\nthe way for a better understanding of the rupture dynamics of liquid films.",
        "positive": "Scale and Nature of Sulcification Patterns: Sulci are surface folds commonly seen in strained soft elastomers and form\nvia a strongly subsubcriticalcritical, yet scale-free instability. Treating the\nthreshold for nonlinear instability as a nonlinear critical point, we explain\nthe nature of sulcus patterns in terms of the scale and translation symmetries\nwhich are broken by the formation of an isolated, small sulcus. Our\nperturbative theory and simulations show that sulcus formation in a thick,\ncompressed slab can arise either as a supercritical or as a weakly subcritical\nbifurcation relative to this nonlinear critical point, depending on the\nboundary conditions. An infinite number of competing, equilibrium patterns\nsimultaneously emerge at this critical point, but the one selected has the\nlowest energy. We give a simple, physical explanation for the formation of\nthese sulcification patterns using an analogy to a solid-solid phase transition\nwith a finite energy of transformation."
    },
    {
        "anchor": "Kinetically engendered sub-spinodal length scales in spontaneous\n  dewetting of thin liquid films: Numerical simulations of spontaneous dewetting of non-slipping, variable\nviscosity unstable thin liquid films on homogeneous substrates reveal the\nexistence of sub-spinodal lengthscales through formation of satellite holes, a\nmarker of nucleated dewetting and/or heterogeneous substrates, in the late\nstages of dewetting if the liquid viscosity decreases continually with\ndecreasing film thickness. These films also show established signatures of\nslipping films such as faster rupture and flatter morphologies in the early\nstages even without invoking any slippage.",
        "positive": "On the long and short-range adhesive interactions in viscoelastic\n  contacts: Recently, tribologists have shown increasing interest in rate-dependent\nphenomena occurring in viscoelastic fractures. However, in some cases,\nconflicting results are obtained despite the use of similar theoretical models.\nFor this reason, we try to shed light on the effects that long and short-range\nadhesion has on the pull-off force in the contact of viscoelastic media by\nexploiting a recently developed numerical model. We find that, in the limit of\nlong-range adhesion, the unloading velocity has little effect on the pull-off\nforce, which is close to the value predicted by Bradley for rigid bodies. In\nsuch case, the detachment process is characterized by a uniform bond-breaking\nof the contact area, and viscous dissipation involves the bulk material. For\nmedium(short)-range adhesion, the pull-off force is instead a monotonic\nincreasing function of the pulling velocity and, at high speeds, reaches a\nplateau that is a function of the adiabatic surface energy. In this case, the\ndetachment process is similar to the opening of a circular crack, and viscous\ndissipation is localized at the contact edge."
    },
    {
        "anchor": "Liquid-solid friction on crystalline surfaces: a perspective: Liquids flowing on solid surfaces experience a friction force. Whereas solid\nfriction is familiar to anyone gifted with the sense of touch, liquid friction\nis much more exotic. Although it was long believed to be infinite, meaning that\ninterfacial liquid molecules stick to solid surfaces, we have known for a few\ndecades that this is not the case and that some materials show extreme liquid\nslippage, which implies a dramatic enhancement of nanoscale pipes' permeability\nto liquid flows. Harnessing liquid friction bears the promise of\nhigh-efficiency membrane separation processes, heat recovery systems, or blue\nenergy harvesting, turning it into a highly strategic field to reduce carbon\nemissions and meet the climate emergency.",
        "positive": "Steric effect of water molecule clusters on electrostatic interaction\n  and electroosmotic transport in aqueous electrolytes: a mean-field approach: We theoretically study the size effect of water molecule clusters not only on\nelectrostatic interaction between two charged surfaces in an aqueous\nelectrolyte but also on electroosmotic transport in a nanofluidic channel.\nApplying a free energy based mean-field approach accounting for different sizes\nof ions and water molecule clusters, we derive a set of coupled equations to\ncompute electrostatic and electroosmotic properties between charged surfaces.\nWe verify that the smaller the size of a water cluster, the stronger the\nelectroosmotic transport in nanofluidic channels. In addition, we find that an\nincrease in size of a water cluster yields a decrease in electrostatic\ninteraction strength between similar or oppositely charged planar surfaces."
    },
    {
        "anchor": "Nonadditivity in the effective interactions of binary charged colloidal\n  suspensions: Based on primitive model computer simulations with explicit microions, we\ncalculate the effective interactions in a binary mixture of charged colloids\nwith species $A$ and $B$ for different size and charge ratios. An optimal\npairwise interaction is obtained by fitting the many-body effective forces.\nThis interaction is close to a Yukawa (or\nDerjaguin-Landau-Verwey-Overbeek(DLVO)) pair potential but the $AB$\ncross-interaction is different from the geometric mean of the two direct $AA$\nand $BB$ interactions. As a function of charge asymmetry, the corresponding\nnonadditivity parameter is first positive, then getting significantly negative\nand is getting then positive again. We finally show that an inclusion of\nnonadditivity within an optimal effective Yukawa model gives better predictions\nfor the fluid pair structure than DLVO-theory.",
        "positive": "Autonomous waves and global motion modes in living active solids: Elastic active matter or active solid consists of self-propelled units\nembedded in an elastic matrix. Active solid resists deformation; the\nshape-preserving property and the intrinsic non-equilibrium nature make active\nsolids a superior component for self-driven devices. Nonetheless, the\nmechanical properties and emergent behavior of active solids are poorly\nunderstood. Using a biofilm-based bacterial active solid, here we discovered\nself-sustained elastic waves with unique wave properties not seen in passive\nsolids, such as power-law scaling of wave speed with activity. Under isotropic\nconfinement, the active solid develops two topologically distinct global motion\nmodes that can be selectively excited, with a surprising step-like frequency\njump at mode transition. Our findings reveal novel spatiotemporal order in\nelastic active matter and may guide the development of solid-state adaptive or\nliving materials."
    },
    {
        "anchor": "Functional surfaces through the creation of adhesion and charged\n  patterns on azopolymer surface relief gratings: We show that an azopolymer can be used to create a supramolecular\narchitecture in a parallel process with patterned surface properties. By\nilluminating with an interference pattern, we created adhesion and charge\npatterns that reflect the molecular ordering. We studied the recording process\nin two limit situations. When birefringence dominates over mass transport, an\nadhesion pattern was recorded even in absence of a surface relief grating\n(SRG). When mass transport dominates, we measured a higher frequency adhesion\nand relief patterns on top of the SRG. We measured an increased negative charge\nin the regions where molecules are expected to be parallel aligned in trans\nconformational state.",
        "positive": "Hyper-aging Dynamics of Nano-clay Suspension: Aqueous suspension of nanoclay Laponite undergoes structural evolution as a\nfunction of time, which enhances its elasticity and relaxation time. In this\nwork we employ effective time approach to investigate long term relaxation\ndynamics by carrying out creep experiments. Typically we observe that the\nmonotonic evolution of elastic modulus shifts to lower aging times while maxima\nin viscous modulus gets progressively broader for experiments carried out on a\nlater date since preparation (idle time) of nanoclay suspension. Application of\neffective time theory produces superposition of all the creep curves\nirrespective of their initial state. The resulting dependence of relaxation\ntime on aging time shows very strong hyper aging dynamics at small idle times,\nwhich progressively weakens to demonstrate linear dependence in the limit of\nvery large idle times. Remarkably this behavior of nanoclay suspension is akin\nto that observed for polymeric glasses. Consideration of aging as a first order\nprocess suggests that continued hyper-aging dynamics causes cessation of aging.\nThe dependence of relaxation time on aging time, therefore, must attenuate\neventually producing linear or weaker dependence on time in order to approach\nprogressively low energy state in the limit of very large times as observed\nexperimentally. We also develop a simple scaling model based on a concept of\naging of an energy well, which qualitatively captures various experimental\nobservations very well leading to profound insight into the hyper-aging\ndynamics of nano-clay suspensions."
    },
    {
        "anchor": "X-ray diffraction and spectroscopic techniques from liquid surfaces and\n  interfaces: X-ray reflectivity and grazing incidence diffraction (XGID) from liquid\nsurfaces are described.",
        "positive": "Mean-field theory of random close packings of axisymmetric particles: Finding the optimal random packing of non-spherical particles is an open\nproblem with great significance in a broad range of scientific and engineering\nfields. So far, this search has been performed only empirically on a\ncase-by-case basis, in particular, for shapes like dimers, spherocylinders and\nellipsoids of revolution. Here, we present a mean-field formalism to estimate\nthe packing density of axisymmetric non-spherical particles. We derive an\nanalytic continuation from the sphere that provides a phase diagram predicting\nthat, for the same coordination number, the density of monodisperse random\npackings follows the sequence of increasing packing fractions: spheres < oblate\nellipsoids < prolate ellipsoids < dimers < spherocylinders. We find the maximal\npacking densities of 73.1% for spherocylinders and 70.7% for dimers, in good\nagreement with the largest densities found in simulations. Moreover, we find a\npacking density of 73.6% for lens-shaped particles, representing the densest\nrandom packing of the axisymmetric objects studied so far."
    },
    {
        "anchor": "Rheology of dilute suspensions of vesicles and red blood cells: We present rheology experiments on dilute solutions of vesicles and red blood\ncells (RBC). Varying the viscosity ratio $\\lambda$ between internal and\nexternal fluids, the microscopic dynamics of suspended objects can be\nqualitatively changed from tank-treading ($tt$) to tumbling ($tb$). We find\nthat in the tt regime the viscosity $\\eta$, decreases when $\\lambda$ increases,\nin contrast with droplet emulsions and elastic capsule theories which are\nsometimes invoked to model RBC dynamics. At a critical $\\lambda$ (close to the\ntt-tb transition) $\\eta$ exhibits a minimum before it increases in the tb\nregime. This is consistent with a recent theory for vesicles. This points to\nthe nontrivial fact that the cytoskeleton in RBC does not alter the qualitative\nevolution of $\\eta$ and that, as far as rheology is concerned, vesicle models\nmight be a better description.",
        "positive": "Elasticity-Dependent Self-assembly of Micro-Templated Chromonic Liquid\n  Crystal Films: We explore micropatterned director structures of aqueous lyotropic chromonic\nliquid crystal (LCLC) films created on square lattice cylindrical-micropost\nsubstrates. The structures are manipulated by modulating the LCLC mesophases\nand their elastic properties via concentration through drying. Nematic LCLC\nfilms exhibit preferred bistable alignment along the diagonals of the micropost\nlattice. Columnar LCLC films, dried from nematics, form two distinct director\nand defect configurations: a diagonally aligned director pattern with local\nsquares of defects, and an off-diagonal configuration with zig-zag defects. The\nformation of these states appears to be tied to the relative splay and bend\nfree energy costs of the initial nematic films. The observed nematic and\ncolumnar configurations are understood numerically using a Landau-de Gennes\nfree energy model. Among other attributes, the work provide first examples of\nquasi-2D micropatterning of LC films in the columnar phase and lyotropic LC\nfilms in general, and it demonstrates alignment and configuration switching of\ntypically difficult-to-align LCLC films via bulk elastic properties."
    },
    {
        "anchor": "Time dependent lyotropic chromonic textures in PDMS-based microfluidic\n  confinements: Nematic and columnar phases of lyotropic chromonic liquid crystals (LCLCs)\nhave been long studied for their fundamental and applied prospects in material\nscience and medical diagnostics. LCLC phases represent different self-assembled\nstates of disc-shaped molecules, held together by noncovalent interactions that\nlead to highly sensitive concentration and temperature dependent properties.\nYet, microscale insights into confined LCLCs, specifically in the context of\nconfinement geometry and surface properties, are lacking. Here, we report the\nemergence of time dependent textures in static disodium chromoglycate (DSCG)\nsolutions, confined in PDMS-based microfluidic devices. We use a combination of\nsoft lithography, surface characterization and polarized optical imaging to\ngenerate and analyze the confinement-induced LCLC textures, and demonstrate\nthat over time, herringbone and spherulite textures emerge due to spontaneous\nnematic (N) to columnar M-phase transition, propagating from the LCLC-PDMS\ninterface into the LCLC bulk. By varying the confinement geometry, anchoring\nconditions and the initial DSCG concentration, we can systematically tune the\ntemporal dynamics of the N to M-phase transition and textural behaviour of the\nconfined LCLC. Since static molecular states register the initial conditions\nfor LC flows, the time dependent boundary and bulk conditions reported here\nsuggest that the local surface-mediated dynamics could be central in\nunderstanding LCLC flows, and in turn, the associated transport properties of\nthis versatile material.",
        "positive": "Intrinsic Free Energy in Active Nematics: Basing our arguments on the theory of active liquid crystals, we demonstrate\nboth analytically and numerically, that the activity can induce an effective\nfree energy which enhances ordering in extensile systems of active rods and in\ncontractile suspensions of active discs. We argue that this occurs because any\nordering fluctuation is enhanced by the flow field it produces. A phase-diagram\nin the temperature-activity plane compares ordering due to a thermodynamic free\nenergy to that resulting from the activity. We also demonstrate that activity\ncan drive variations in concentration, but for a different physical reason that\nrelies on the separation of hydrodynamic and diffusive timescales."
    },
    {
        "anchor": "The Freedericksz transition in a spatially varying magnetic field: Much is known about the Freedericksz transition induced by uniform electric\nand magnetic fields in nematic liquid crystals. Here we study the effects of a\nspatially varying field on the transition. We study the response of a nematic\nto a magnetic field with cylindrical symmetry, and find that since the field\nmagnitude varies in the plane of the cell, the transition vanishes.",
        "positive": "Local volume conservation in concentrated electrolytes is governing\n  charge transport in electric fields: While ion transport processes in concentrated electrolytes, e.g. based on\nionic liquids (IL), are a subject of intense research, the role of conservation\nlaws and reference frames is still a matter of debate. Employ-ing\nelectrophoretic NMR, we show that momentum conservation, a typical prerequisite\nin molecular dynamics (MD) simulations, is not governing ion transport.\nInvolving density measurements to deter-mine molar volumes of distinct ion\nspecies, we propose that conservation of local molar species volumes is the\ngoverning constraint for ion transport. The experimentally quantified net\nvolume flux is found as zero, implying a non-zero local momentum flux, as\ntested in pure ILs and IL-based electrolytes for a broad variety of\nconcentrations and chemical compositions. This constraint is consistent with\nincom-pressibility, but not with a local application of momentum conservation.\nThe constraint affects the calcu-lation of transference numbers as well as\ncomparisons of MD results to experimental findings."
    },
    {
        "anchor": "The influence of bond-rigidity and cluster diffusion on the\n  self-diffusion of hard spheres with square-well interaction: Hard spheres interacting through a square-well potential were simulated using\ntwo different methods: Brownian Cluster Dynamics (BCD) and Event Driven\nBrownian Dynamics (EDBD). The structure of the equilibrium states obtained by\nboth methods were compared and found to be almost the identical. Self diffusion\ncoefficients ($D$) were determined as a function of the interaction strength.\nThe same values were found using BCD or EDBD. Contrary the EDBD, BCD allows one\nto study the effect of bond rigidity and hydrodynamic interaction within the\nclusters. When the bonds are flexible the effect of attraction on $D$ is\nrelatively weak compared to systems with rigid bonds. $D$ increases first with\nincreasing attraction strength, and then decreases for stronger interaction.\nIntroducing intra-cluster hydrodynamic interaction weakly increases $D$ for a\ngiven interaction strength. Introducing bond rigidity causes a strong decrease\nof $D$ which no longer shows a maximum as function of the attraction strength.",
        "positive": "Effect of cholesterol on the mechanical stability of gel-phase\n  phospholipid bilayers studied by AFM force spectroscopy: The low sliding friction of articular cartilage in the major joints , which\nis crucial for its homeostasis and for joint health, has been attributed to\nlipid bilayers forming lubricious boundary layers at its surface. The\nrobustness of such layers, and thus their lubrication efficiency at joint\npressures, depends on the lipids forming them, including cholesterol, which may\nact to strengthen of weaken the bilayer. A systematic study using an Atomic\nForce Microscope (AFM) was carried out to understand the effect of cholesterol\non the nanomechanical stability of two saturated phospholipids, DSPC\n(1,2-distearoyl-sn-glycero-3-phosphatidlycholine) and DPPC\n(1,2-dipalmitoyl-sn-glycero-phosphatidylcholine), that differ in acyl chain\nlengths. Measurements were carried out both in water and in phosphate buffer\nsolution (PBS). The nanomechanical stability of the lipid bilayers was\nquantitatively evaluated by measuring the breakthrough force needed to puncture\nthe bilayer by the AFM tip. The molar fractions of cholesterol incorporated in\nthe bilayers were 10% and 40%. We found that for both DSPC and DPPC,\ncholesterol significantly decreases the mechanical stability of the bilayers in\nsolid ordered (SO) phase. In accordance with the literature, the strengthening\neffect of salt on the lipid bilayers was also observed. For DPPC with 10 mol %\ncholesterol, the effect of tip properties and the experimental procedure\nparameters on the breakthrough forces were also studied. Tip radius (2 - 42\nnm), material (Si, Si3N4, Au) and loading rate (40 - 1000 nm/s) were varied\nsystematically. The values of the breakthrough forces measured were not\nsignificantly affected by any of these parameters, showing that the weakening\neffect of cholesterol does not result from such changes in experimental\nconditions. This study helps to shed light on the mechanism of physiological\nlubrication."
    },
    {
        "anchor": "Independence of the relaxation of a supercooled fluid of its microscopic\n  dynamics: need for yet another extension of the mode-coupling theory: Using Brownian Dynamics computer simulations we show that the relaxation of a\nsupercooled Brownian system is qualitatively the same as that of a Newtonian\nsystem. In particular, near the so-called mode-coupling transition temperature,\ndynamic properties of the Brownian system exhibit the same deviations from\npower-law behavior as those of the Newtonian one. Thus, similar dynamical\nevents cut off the idealized mode-coupling transition in Brownian and Newtonian\nsystems. We discuss implications of this finding for extended mode-coupling\ntheory. In addition, we point out and discuss the difference between our\nfindings and experimental results, and present an alternative interpretation of\nsome of our simulation data.",
        "positive": "Non-Gaussian displacements in active transport on a carpet of motile\n  cells: We study the dynamics of micron-sized particles on a layer of motile cells.\nThis cell carpet acts as an active bath that propels passive tracer particles\nvia direct mechanical contact. The resulting nonequilibrium transport shows a\ncrossover from superdiffusive to normal-diffusive dynamics. The particle\ndisplacement distribution is distinctly non-Gaussian even in the limit of long\nmeasurement times -- different from typically reported Fickian yet non-Gaussian\ntransport, for which Gaussianity is restored beyond some system-specific\ncorrelation time. We obtain the distribution of diffusion coefficients from the\nexperimental data and introduce a model for the displacement distribution that\nmatches the experimentally observed non-Gaussian statistics and argue why\nsimilar transport properties are expected for many composite active matter\nsystems."
    },
    {
        "anchor": "Pattern formation in a fully-3D segregating granular flow: Segregation patterns of size-bidisperse particle mixtures in a\nfully-three-dimensional flow produced by alternately rotating a spherical\ntumbler about two perpendicular axes are studied over a range of particle sizes\nand volume ratios using both experiments and a continuum model. Pattern\nformation results from the interaction of size segregation with chaotic regions\nand non-mixing islands of the flow. Specifically, large particles in the\nflowing surface layer are preferentially deposited in non-mixing islands\ndespite the effects of collisional diffusion and chaotic transport. The\nprotocol-dependent structure of the unstable manifolds of the flow surrounding\nthe non-mixing islands provides further insight into why certain segregation\npatterns are more robust than others.",
        "positive": "Orientational correlations in fluids with quenched disorder: Snapshots of colloidal particles moving on disordered two-dimensional\nsubstrates can be used to extract equal-time many-body correlations in their\npositions. To understand the systematics of these correlations, we perform\nMonte Carlo simulations of a two-dimensional model fluid placed in a quenched\ndisordered background. We use configurations generated from these simulations\nto compute translational and orientational two-point correlations at equal\ntime, concentrating on correlations in local orientational order as a function\nof density and disorder strength. We calculate both the disorder averaged\nversion of conventional two-point correlation functions for orientational\norder, as well as the disorder averaged version of a novel correlation function\nof time-averaged disorder-induced inhomogeneities in local orientation\nanalogous to the Edwards-Anderson correlation function in spin systems. We\ndemonstrate that these correlations can exhibit interesting non-monotonic\nbehavior in proximity to the underlying fluid-solid transition and suggest that\nthis prediction should be experimentally accessible."
    },
    {
        "anchor": "Force networks and elasticity in granular silos: We have made experimental observations of the force networks within a\ntwo-dimensional granular silo similar to the classical system of Janssen.\nModels like that of Janssen predict that pressure within a silo saturates with\ndepth as the result of vertical forces being redirected to the walls of the\nsilo where they can then be carried by friction. By averaging ensembles of\nexperimentally-obtained force networks in different ways, we compare the\nobserved behavior with various predictions for granular silos. We identify\nseveral differences between the mean behavior in our system and that predicted\nby Janssen-like models: We find that the redirection parameter describing how\nthe force network transfers vertical forces to the walls varies with depth. We\nfind that changes in the preparation of the material can cause the pressure\nwithin the silo to either saturate or to continue building with depth. Most\nstrikingly, we observe a non-linear response to overloads applied to the top of\nthe material in the silo. For larger overloads we observe the previously\nreported \"giant overshoot\" effect where overload pressure decays only after an\ninitial increase [G. Ovarlez et al., Phys. Rev. E 67, 060302(R) (2003)]. For\nsmaller overloads we find that additional pressure propagates to great depth.\nThis effect depends on the particle stiffness, as given for instance by the\nYoung's modulus, E, of the material from which the particles are made.\nImportant measures include E, the unscreened hydrostatic pressure, and the\napplied load. These experiments suggest that when the load and the particle\nweight are comparable, particle elasticity acts to stabilize the force network,\nallowing non-linear network effects to be seen in the mean behavior.",
        "positive": "Monte Carlo SImulation of Polymers: Coarse-Grained Models: A coarse-grained simulation model eliminates microscopic degrees of freedom\nand represents a polymer by a simplified structure. A priori, two classes of\ncoarse-grained models may be distinguished: those which are designed for a\nspecific polymer and reflect the underlying atomistic details to some extent,\nand those which retain only the most basic features of a polymer chain (chain\nconnectivity, short-range excluded-volume interactions, etc.).\n  In this review we mainly focus on the second class of generic polymer models,\nwhile the first class of specific coarse-grained models is only touched upon\nbriefly."
    },
    {
        "anchor": "Active Matter in Lateral Parabolic Confinement: From Subdiffusion to\n  Superdiffusion: In this work we studied the diffusive behavior of active brownian particles\nunder lateral parabolic confinement. The results showed that we go from\nsubdiffusion to ballistic motion as we vary the angular noise strength and\nconfinement intensity. We argued that the subdiffusion regimes appear as\nconsequence of the restricted space available for diffusion (achieved either\nthrough large confinement and/or large noise); we saw that when there are large\nconfinement and noise intensity, a similar configuration to single file\ndiffusion appears; on the other hand, normal and superdiffusive regimes may\noccur due to low noise (longer persistent motion), either through exploring a\nwider region around the potential minimum in the transverse direction (low\nconfinement), or by forming independent clusters (high confinement).",
        "positive": "Effect of Screening of Intermicellar Interactions on the Linear and\n  Nonlinear Rheology of a Viscoelastic Gel: We report our studies of the linear and nonlinear rheology of aqueous\nsolutions of the surfactant cetyl trimethylammonium tosylate (CTAT) with\nvarying amounts of sodium chloride (NaCl). The CTAT concentration is fixed at\n42mM and the salt concentration is varied between 0mM to 120mM. On increasing\nthe salt (NaCl) concentration, we see three distinct regimes in the zero-shear\nviscosity and the high frequency plateau modulus data. In regime I, the\nzero-shear viscosity shows a weak increase with salt concentration due to\nenhanced micellar growth. The decrease in the zero-shear viscosities with salt\nconcentration in regimes I I and III can be explained in terms of\ninter-micellar branching. The most intriguing feature of our data however, is\nthe anomalous behavior of the high frequency plateau modulus in regime II (0.12\n$\\le \\frac{[NaCl]}{[CTAT]} \\le$ 1. 42). In this regime, the plateau modulus\n{\\it increases} with an increase in NaCl concentration. This is highly\ncounter-intuitive, since the correlation length of concentration fluctuations\nand hence the plateau modulus $G_{\\circ}$ are not expected to change\nappreciably in the semi-dilute regime. We propose to explain the changes in\nregime II in terms of the unbinding of the organic counterions (tosylate) from\nthe CTA$^{+}$ surfaces on the addition of NaCl. In the nonlinear flow curves of\nthe samples with high salt content, significant deviations from the predictions\nof the Giesekus model for entangled micelles are observed."
    },
    {
        "anchor": "Ion-Specific Hydration Effects: Extending the Poisson-Boltzmann Theory: In aqueous solutions, dissolved ions interact strongly with the surrounding\nwater, thereby modifying the solution properties in an ion-specific manner.\nThese ion-hydration interactions can be accounted for theoretically on a\nmean-field level by including phenomenological terms in the free energy that\ncorrespond to the most dominant ion-specific interactions. Minimizing this free\nenergy leads to modified Poisson-Boltzmann equations with appropriate boundary\nconditions. Here, we review how this strategy has been used to predict some of\nthe ways ion-specific effects can modify the forces acting within and between\ncharged interfaces immersed in salt solutions.",
        "positive": "Indentation of concave power law profiles with arbitrary exponents: We study analytically and numerically the process of indentation of\ncylindrical rigid indenter with concave face in form of a power-law function.\nIn the well-known case of a parabolic concave indenter, the contact starts at\nsharp edges of the indenter and spreads inwards with increasing indentation\ndepth. For all profiles with the exponent larger than 2, the contact area first\nspreads from the boarder inwards, but then a contact is established in the\ncenter of the indenter. Finally, the outer ring spreads inwards and the central\ncontact area outwards until the complete contact is achieved. The critical\nindentation depth for the full contact is calculated ones proceeding from the\nfull contact and looking for the condition of vanishing pressure and also\nproceeding from incomplete contact (in this case numerically, using Boundary\nElement Method). The results of both approaches coincide."
    },
    {
        "anchor": "Gas permeation through a polymer network: We study the diffusion of gas molecules through a two-dimensional network of\npolymers with the help of Monte Carlo simulations. The polymers are modeled as\nnon-interacting random walks on the bonds of a two-dimensional square lattice,\nwhile the gas particles occupy the lattice cells. When a particle attempts to\njump to a nearest-neighbor empty cell, it has to overcome an energy barrier\nwhich is determined by the number of polymer segments on the bond separating\nthe two cells. We investigate the gas current $J$ as a function of the mean\nsegment density $\\rho$, the polymer length $\\ell$ and the probability $q^{m}$\nfor hopping across $m$ segments. Whereas $J$ decreases monotonically with\n$\\rho$ for fixed $\\ell$, its behavior for fixed $\\rho$ and increasing $\\ell$\ndepends strongly on $q$. For small, non-zero $q$, $J$ appears to increase\nslowly with $\\ell$. In contrast, for $q=0$, it is dominated by the underlying\npercolation problem and can be non-monotonic. We provide heuristic arguments to\nput these interesting phenomena into context.",
        "positive": "Fluid-fluid phase behaviour in the explicit solvent ionic model: hard\n  spherocylinder solvent molecules: We study a fluid-fluid phase transition of the explicit solvent model\nrepresented as a mixture of the restricted primitive model (RPM) of ionic fluid\nand neutral hard spherocylinders (HSC). To this end, we combine two theoretical\napproaches, i.e., the scale particle theory (SPT) and the associative mean\nspherical approximation (AMSA). Whereas the SPT is sufficient to provide a\nrather good description of a reference system taking into account hard-core\ninteractions, the AMSA is known to be efficient in treating the Coulomb\ninteractions between the ions. Alternatively, we also use the mean spherical\napproximation (MSA) for comparison. In general, both approximations lead to\nsimilar qualitative results for the phase diagrams: the region of coexisting\nenvelope becomes broader and shifts towards larger densities and higher\ntemperatures when the pressure increases. However, the AMSA and the MSA produce\ndifferent concentration dependences, i.e., contrary to the MSA, the AMSA phase\ndiagrams show that the high-density phase mostly consists of the ions for all\npressures considered. To demonstrate the effect of asphericity of solvent\nmolecules on the fluid-fluid phase transition, we consider an \"equivalent\"\nmixture in which the HSC particles are replaced by hard spheres (HS) of the\nsame volume. It is observed that in the case of HSC solvent (RPM-HSC model),\nthe region of phase coexistence is wider than for the case of the solvent\nmolecules being of spherical shape (RPM-HS model). It is also found that the\ncritical temperature is higher in the RPM-HSC model than in the RPM-HS model,\nthough it becomes the same at higher pressures in the MSA, while in the AMSA\nthis difference remains essential."
    },
    {
        "anchor": "Dipolar Poisson-Boltzmann Equation: Ions and Dipoles Close to Charged\n  Surfaces: We present an extension to the Poisson-Boltzmann model where the dipolar\nfeatures of solvent molecules are taken explicitly into account. The\nformulation is derived at mean-field level and can be extended to any order in\na systematic expansion. It is applied to a two-plate system with oppositely\ncharged surfaces. The ion distribution and profiles in the dipolar order\nparameter are calculated and can result in a large correction to the\ninter-plate pressure.",
        "positive": "Wetting of Water on Graphene: The wetting properties of graphene have proven controversial and difficult to\nassess. The presence of a graphene layer on top of a substrate does not\nsignificantly change the wetting properties of the solid substrate, suggesting\nthat a single graphene layer does not affect the adhesion between the wetting\nphase and the substrate. However, wetting experiments of water on graphene show\ncontact angles that imply a large amount of adhesion. Here, we investigate the\nwetting of graphene by measuring the mass of water vapor adsorbing to graphene\nflakes of different thickness at different relative humidities. Our experiments\nunambiguously show that the thinnest of graphene flakes do not adsorb water,\nfrom which it follows that the contact angle of water on these flakes is ~180o.\nThicker flakes of graphene nanopowder, on the other hand, do adsorb water. A\ncalculation of the van der Waals (vdW) interactions that dominate the\nadsorption in this system confirms that the adhesive interactions between a\nsingle atomic layer of graphene and water are so weak that graphene is\nsuperhydrophobic. The observations are confirmed in an independent experiment\non graphene-coated water droplets that shows that it is impossible to make\nliquid 'marbles' with molecularly thin graphene."
    },
    {
        "anchor": "Chiral shape fluctuations and the origin of chirality in cholesteric\n  phases of DNA origamis: Lyotropic cholesteric liquid crystal phases are ubiquitously observed in\nbiological and synthetic polymer solutions, characterized by a complex\ninterplay between thermal fluctuations, entropic and enthalpic forces. The\nelucidation of the link between microscopic features and macroscopic chiral\nstructure, and of the relative roles of these competing contributions on phase\norganization, remains a topical issue. Here we provide theoretical evidence of\na novel mechanism of chirality amplification in lyotropic liquid crystals,\nwhereby phase chirality is governed by fluctuation-stabilized helical\ndeformations in the conformations of their constituent molecules. Our results\ncompare favorably to recent experimental studies of DNA origami assemblies and\ndemonstrate the influence of intra-molecular mechanics on chiral\nsupra-molecular order, with potential implications for a broad class of\nexperimentally-relevant colloidal systems.",
        "positive": "Intercalation of a Nonionic Surfactant (C10E3) bilayer into a\n  Na-Montmorillonite Clay: A nonionic surfactant, the tri-ethylene glycol mono n-decyl ether (C10E3),\ncharacterized by its lamellar phase state, was introduced in the interlayer of\na Na-montmorillonite clay at several concentrations. The synthesized\norganoclays were characterized by Small Angle X-Ray Scattering in conjunction\nwith Fourier Transform Infrared spectroscopy, and adsorption isotherms.\nExperiments showed that a bilayer of C10E3 was intercalated into the interlayer\nspace of the naturally exchanged Na-montmorillonite, resulting in the\naggregation of the lyotropic liquid crystal state in the lamellar phase. This\nbehavior strongly differs from previous observations of confinement of nonionic\nsurfactants in clays where the expansion of the interlayer space was limited to\ntwo monolayers parallel to the silicate surface and cationic surfactants in\nclays where the intercalation of organic compounds is introduced into the clay\ngalleries through ion exchange. The confinement of a bilayer of C10E3 nonionic\nsurfactant in clays offers new perspectives for the realization of hybrid\nnanomaterials since the synthesized organoclays preserve the electrostatic\ncharacteristics of the clays, thus allowing further ion exchange, while\npresenting at the same time a hydrophobic surface and a maximum opening of the\ninterlayer space for the adsorption of neutral organic molecules of important\nsize with functional properties."
    },
    {
        "anchor": "Critical adsorption of polyelectrolytes onto planar and convex highly\n  charged surfaces: the nonlinear Poisson-Boltzmann approach: We study the adsorption-desorption transition of polyelectrolyte chains onto\nplanar, cylindrical and spherical surfaces with arbitrarily high surface charge\ndensities by massive Monte Carlo computer simulations. We examine in detail how\nthe well known scaling relations for the threshold transition-demarcating the\nadsorbed and desorbed domains of a polyelectrolyte near weakly charged\nsurfaces-are altered for highly charged interfaces. In virtue of high surface\npotentials and large surface charge densities, the Debye-Hueckel approximation\nis often not feasible and the nonlinear Poisson-Boltzmann approach should be\nimplemented. At low salt conditions, for instance, the electrostatic potential\nfrom the nonlinear Poisson--Boltzmann equation is smaller than the\nDebye-Hueckel result, such that the required critical surface charge density\nfor polyelectrolyte adsorption $\\sigma_c$ increases. The nonlinear relation\nbetween the surface charge density and electrostatic potential leads to a\nsharply increasing critical surface charge density with growing ionic strength,\nimposing an additional limit to the critical salt concentration above which no\npolyelectrolyte adsorption occurs at all. We contrast our simulations findings\nwith the known scaling results for weak critical polyelectrolyte adsorption\nonto oppositely charged surfaces for the three standard geometries. Finally, we\ndiscuss some applications of our results for some physical-chemical and\nbiophysical systems.",
        "positive": "Self-sorting in two-dimensional assemblies of simple chiral molecules: Structural modification of adsorbed overlayers by means of external factors\nis an important objective in the fabrication of stimuli-responsive materials\nwith adjustable physicochemical properties. In this contribution we present a\ncoarse-grained Monte Carlo model of the confinement-induced chiral self-sorting\nof hockey stick-shaped enantiomers adsorbed on a triangular lattice. It is\nassumed that the adsorbed overlayer consists of \"normal\" molecules that are\ncapable of adopting any of the six planar orientations imposed by the symmetry\nof the lattice and molecular directors having only one permanent orientation,\nthat reflect the coupling of these species with an external directional field.\nOur investigations focus on the influence of the amount fraction of the\nmolecular directors, temperature and surface coverage on the extent of the\nchiral segregation. The simulated results demonstrate that the molecular\ndirectors can have a significant effect on the ordering in enantiopure\noverlayers, while for the corresponding racemates their role is largely\ndiminished. These findings can be helpful in designing strategies to improve\nmethods of fabrication of homochiral surfaces and enantioselective adsorbents."
    },
    {
        "anchor": "Pentagon deposits unpack under gentle tapping: We present results from simulations of regular pentagons arranged in a\nrectangular die. The particles are subjected to vertical tapping. We study the\nbehavior of the packing fraction, number of contacts and arch distributions as\na function of the tapping amplitude. Pentagons show peculiar features as\ncompared with disks. As a general rule, pentagons tend to form less arches than\ndisks. Nevertheless, as the tapping amplitude is decreased, the typical size of\nthe pentagon arches grows significantly. As a consequence, a pentagon packing\nreduces its packing fraction when tapped gently in contrast with the behavior\nfound in rounded particle deposits.",
        "positive": "Mesoscopic inhomogeneities in concentrated electrolytes: A mesoscopic theory for water-in-salt electrolytes combining density\nfunctional and field-theoretic methods is developed in order to explain the\nunexpectedly large period of the oscillatory decay of the disjoining pressure\nobserved in recent experiments for the LiTFSI (lithium\nbis(trifluoromethylsulfonyl)-imide) salt [T. S. Groves et. al., J. Phys. Chem.\nLett. {\\bf 12},1702 (2021)]. We assumed spherical ions with different\ndiameters, and implicit solvent inducing strong, short-range attraction between\nions of the same sign. For this highly simplified model, we calculated\ncorrelation functions. Our results indicate that mesoscopic inhomogeneities can\noccur when the sum of the Coulomb and the water-mediated interactions between\nlike ions is attractive at short- and repulsive at large distances. We adjusted\nthe attractive part of the potential to the water-in-LiTFSI electrolyte, and\nobtained both the period and the decay rate of the correlations in a\nsemiquantitative agreement with the experiment. In particular, the decay length\nof the correlations increases nearly linearly with the volume fraction of ions."
    },
    {
        "anchor": "Particle response during the yielding transition of colloidal glasses: Yielding is central to the relaxation, flow and fracture of a wide range of\nsoft and molecular glasses, but its microscopic origin remains unclear. Here,\nwe elucidate the yielding of a colloidal glass by using x-ray scattering to\nmonitor the structure factor during the yielding process. We apply a recently\nintroduced combination of small-angle x-ray scattering and rheology to the\noscillatory shear, and follow the structure factor during the increasing strain\namplitude. Surprisingly, we observe a sharp transition in the orientational\nordering of the nearest-neighbor structure upon yielding, in contrast to the\nsmooth variation of the viscoelastic moduli. This transition is accompanied by\na sudden change of intensity fluctuations towards Gaussian distributions. We\nthus identify yielding as a new, dynamically induced transition of the glass in\nresponse to the applied shear.",
        "positive": "Fast decay of the velocity autocorrelation function in dense shear flow\n  of inelastic hard spheres: We find in complementary experiments and event driven simulations of sheared\ninelastic hard spheres that the velocity autocorrelation function $\\psi(t)$\ndecays much faster than $t^{-3/2}$ obtained for a fluid of elastic spheres at\nequilibrium. Particle displacements are measured in experiments inside a\ngravity driven flow sheared by a rough wall. The average packing fraction\nobtained in the experiments is 0.59, and the packing fraction in the\nsimulations is varied between 0.5 and 0.59. The motion is observed to be\ndiffusive over long times except in experiments where there is layering of\nparticles parallel to boundaries, and diffusion is inhibited between layers.\nRegardless, a rapid decay of $\\psi(t)$ is observed, indicating that this is a\nfeature of the sheared dissipative fluid, and is independent of the details of\nthe relative particle arrangements. An important implication of our study is\nthat the non-analytic contribution to the shear stress may not be present in a\nsheared inelastic fluid, leading to a wider range of applicability of kinetic\ntheory approaches to dense granular matter."
    },
    {
        "anchor": "The Role of the Functionality in the Branch Point Motion in Symmetric\n  Star Polymers: A Combined Study by Simulations and Neutron Spin Echo: We investigate the effect of the number of arms (functionality f ) on the\nmobility of the branch point in symmetric star polymers. For this purpose we\ncarry out large-scale molecular dynamics simulations of simple bead-spring\nstars and neutron spin echo (NSE) spectroscopy experiments on center labeled\npolyethylene stars. This labeling scheme unique to neutron scattering allows us\nto directly observe the branch point motion on the molecular scale by measuring\nthe dynamic structure factor. We investigate the cases of different\nfunctionalities f = 3, 4 and 5 for different arm lengths. The analysis of the\nbranch point fluctuations reveals a stronger localization with increasing\nfunctionality, following 2/f-scaling. The dynamic structure factors of the\nbranch point are analyzed in terms of a modified version, incorporating dynamic\ntube dilution (DTD), of the Vilgis-Boue model for cross-linked networks [J.\nPolym. Sci. B 1988, 26, 2291-2302]. In DTD the tube parameters are renormalized\nwith the tube survival probability \\phi(t). As directly measured by the\nsimulations, \\phi(t) is independent of f and therefore the theory predicts no\nf-dependence of the relaxation of the branch point. The theory provides a good\ndescription of the NSE data and simulations for intermediate times. However,\nthe simulations, which have access to much longer time scales, reveal the\nbreakdown of the DTD prediction since increasing the functionality actually\nleads to a slower relaxation of the branch point.",
        "positive": "Group analysis of the membrane shape equation: A system of PDE describing bilayers amphiphilic membranes is studied by Lie\ngroup analysis. This algorithmic approach allows us to show all the symmetries\nof the system, to determine all possible symmetry reductions, to recover the\naxisymmetric solutions, obtained by other euristic methods, and finally to\naddress the question of new similarity solutions."
    },
    {
        "anchor": "Collective beating of artificial microcilia: We combine technical, experimental and theoretical efforts to investigate the\ncollective dynamics of artificial microcilia in a viscous fluid. We take\nadvantage of soft-lithography and colloidal self-assembly to devise microcapets\nmade of hundreds of slender magnetic rods. This novel experimental setup is\nused to investigate the dynamics of extended cilia arrays driven by a\nprecessing magnetic field. Whereas the dynamics of an isolated cilium is a\nrigid body rotation, collective beating results in a symmetry breaking of the\nprecession patterns. The trajectories of the cilia are anisotropic and\nexperience a significant structural evolution as the actuation frequency\nincreases. We present a minimal model to account for our experimental findings\nand demonstrate how the global geometry of the array imposes the shape of the\ntrajectories via long range hydrodynamic interactions.",
        "positive": "Amorphous Entangled Active Matter: The design of amorphous entangled systems, specifically from soft and active\nmaterials, has the potential to open exciting new classes of active,\nshape-shifting, and task-capable 'smart' materials. However, the global\nemergent mechanics that arises from the local interactions of individual\nparticles are not well understood. In this study, we examine the emergent\nproperties of amorphous entangled systems in three different examples: an\nin-silico \"smarticle\" collection, its robophysical chain, and living entangled\naggregate of worm blobs (L. variegatus). In simulations, we examine how\nmaterial properties change for a collective composed of dynamic three-link\nrobots. We compare three methods of controlling entanglement in a collective:\nexternally oscillations, shape-changes, and internal oscillations. We find that\nlarge-amplitude changes of the particle's shape using the shape-change\nprocedure produced the highest average number of entanglements, with respect to\nthe aspect ratio (l/w), improving the tensile strength of the collective. We\ndemonstrate application of these simulations in two experimental systems:\nrobotic chains and entangled worm blobs. In the robophysical models, we find\nemergent auxeticity behavior upon straining the confined collective. And\nfinally, we show how the individual worm activity in a blob can be controlled\nthrough the ambient dissolved oxygen in water, leading to complex emergent\nproperties of the living entangled collective, such as solid-like entanglement\nand tumbling. Taken together, our work reveals principles by which future\nshape-modulating, potentially soft robotic systems may dynamically alter their\nmaterial properties, advancing our understanding of living entangled materials,\nwhile inspiring new classes of synthetic emergent super-materials."
    },
    {
        "anchor": "Fluid adsorption at a non-planar wall: roughness induced first-order\n  wetting: We study the problem of fluid adsorption at a non-planar wall with a view to\nunderstanding the influence of surface roughness on the wetting transition.\nStarting from an appropriate Landau-type free energy functional we develop a\nlinear response theory relating the free energy of the non-planar system to the\ncorrelation functions in its planar counterpart. We generalize the well known\ngraphical construction method used to study the planar surface phase diagram\nand derive analytical expressions for the shift in the phase boundary for first\nand second-order wetting transitions. Of particular interest is the influence\nof surface roughness on a second order wetting transition which is driven first\norder, even for small deviations from the plane.",
        "positive": "Shear yielding and shear jamming of dense hard sphere glasses: We investigate the response of dense hard sphere glasses to a shear strain,\nin a wide range of pressures ranging from the glass transition to the\ninfinite-pressure jamming point. The phase diagram in the density-shear strain\nplane is calculated analytically using the mean field infinite dimensional\nsolution. We find that just above the glass transition, the glass generically\nyields at a finite shear strain. The yielding transition, in the mean field\npicture, is a spinodal point in presence of disorder. At higher densities,\ninstead, we find that the glass generically jams at a finite shear strain: the\njamming transition prevents yielding. The shear yielding and shear jamming\nlines merge in a critical point, close to which the system yields at extremely\nlarge shear stress. Around this point, a highly non-trivial yielding dynamics\ncharacterized by system-spanning disordered fractures is expected."
    },
    {
        "anchor": "Entropic torque: Quantitative predictions are presented of a depletion-induced torque and\nforce acting on a single colloidal hard rod immersed in a solvent of hard\nspheres close to a planar hard wall. This torque and force, which are entirely\nof entropic origin, may play an important role for the key-lock principle,\nwhere a biological macromolecule (the key) is only functional in a particular\norientation with respect to a cavity (the lock).",
        "positive": "Periodic polymers with increasing repetition unit: Energy structure and\n  carrier transfer: We study the energy structure and the transfer of an extra electron or hole\nalong periodic polymers made of $N$ monomers, with a repetition unit made of\n$P$ monomers, using a Tight-Binding wire model, where a site is a monomer\n(e.g., in DNA, a base pair), for $P$ even, and deal with two categories of such\npolymers: made of the same monomer (GC..., GGCC..., etc) and made of different\nmonomers (GA..., GGAA..., etc). We calculate the HOMO and LUMO eigenspectra,\ndensity of states and HOMO-LUMO gap and find some limiting properties these\ncategories possess, as $P$ increases. We further examine the properties of the\nmean over time probability to find the carrier at each monomer. We introduce\nthe weighted mean frequency of each monomer and the total weighted mean\nfrequency of the whole polymer, as a measure of the overall transfer frequency\ncontent. We study the pure mean transfer rates. These rates can be increased by\nmany orders of magnitude with appropriate sequence choice. Generally,\nhomopolymers display the most efficient charge transfer. Finally, we compare\nthe pure mean transfer rates with experimental transfer rates obtained by\ntime-resolved spectroscopy."
    },
    {
        "anchor": "Opposed flow focusing: evidence of a second order jetting transition: We propose a novel microfluidic \"opposed-flow\" geometry in which the\ncontinuous fluid phase is fed into a junction in a direction opposite the\ndispersed phase. This pulls out the dispersed phase into a micron-sized jet,\nwhich decays into micron-sized droplets. As the driving pressure is tuned to a\ncritical value, the jet radius vanishes as a power law down to sizes below 1\n$\\mu$m. By contrast, the conventional \"coflowing\" junction leads to a first\norder jetting transition, in which the jet disappears at a finite radius of\nseveral $\\mu$m, to give way to a \"dripping\" state, resulting in much larger\ndroplets. We demonstrate the effectiveness of our method by producing the first\nmicrofluidic silicone oil emulsions with a sub micron particle radius, and\nutilize these droplets to produce colloidal clusters.",
        "positive": "Dislocation Dynamics in Rayleigh-B\u00e9nard Convection: Theoretical results on the dynamics of dislocations in Rayleigh-B\\'enard\nconvection are reported both for Swift-Hohenberg models and the Boussinesq\nequations. For intermediate Prandtl numbers the motion of dislocations is found\nto be driven by the superposition of two independent contributions: (i) the\nPeach-Koehler force derived from the change of a Lyapunov potential with\npattern wave number; (ii) a non-potential advection force on the dislocation\ncore by its self-generated mean flow. Their competition allows for the first\ntime to understand the experimentally observed bound dislocation pairs."
    },
    {
        "anchor": "Sequence-dependent spin-selective tunneling along double-stranded DNA: We report spin-selective tunneling of electrons along natural and artificial\ndouble-stranded DNA (dsDNA) sandwiched by nonmagnetic leads. The results reveal\nthat the spin polarization strongly depends on the dsDNA sequence and is\ndominated by its end segment. Both genomic and artificial dsDNA could be\nefficient spin filters. The spin-filtering effects are sensitive to point\nmutation which occurs in the end segment. These results are in good agreement\nwith recent experiments and are robust against various types of disorder, and\ncould help for designing DNA-based spintronic devices.",
        "positive": "Nonlinear rheology of dense colloidal systems with short-ranged\n  attraction: A mode-coupling theory analysis: The nonlinear rheology of glass-forming colloidal suspensions with\nshort-ranged attractions is discussed within the integration-through transients\nframework combined with the mode-coupling theory of the glass transition\n(ITT-MCT). Calculations are based on the square-well system (SWS), as a model\nfor colloid-polymer mixtures. The high-density regime featuring reentrant\nmelting of the glass upon increasing the attraction strength, and the crossover\nfrom repulsive glasses formed at weak attraction to attractive glasses formed\nat strong attraction, are discussed. Flow curves are found in qualitative\nagreement with experimental data, featuring a strong increase in the yield\nstress, and, for suitable interaction parameters, the crossover between two\nyield stresses. The yield strain, defined as the position of the stress\novershoot under startup flow, is found to be proportional to the attraction\nrange for strong attraction. At weak and intermediate attraction strength, the\ncombined effects of hard-core caging and attraction-driven bonding result in a\nricher dependence on the parameters. The first normal-stress difference\nexhibits a weaker dependence on short-ranged attractions as the shear stress,\nsince the latter is more sensitive the short-wavelength features of the static\nstructure."
    },
    {
        "anchor": "Free-energy functional for freezing transitions: Hard sphere systems\n  freezing into crystalline and amorphous structures: A free-energy functional that contains both the symmetry conserved and\nsymmetry broken parts of the direct pair correlation function has been used to\ninvestigate the freezing of a system of hard spheres into crystalline and\namorphous structures. The freezing parameters for fluid-crystal transition have\nbeen found to be in very good agreement with the results found from\nsimulations. We considered amorphous structures found from the molecular\ndynamics simulations at packing fractions $\\eta$ lower than the glass close\npacking fraction $\\eta_{J}$ and investigated their stability compared to that\nof a homogeneous fluid. The existence of free-energy minimum corresponding to a\ndensity distribution of overlapping Gaussians centered around an amorphous\nlattice depicts the deeply supercooled state with a heterogeneous density\nprofile.",
        "positive": "Thin nematic films: anchoring effects and stripe instability revisited: We study theoretically the formation of long-wavelength instability patterns\nobserved at spreading of nematic droplets on liquid substrates. The role of\nsurface-like elastic terms such as saddle-splay and anchoring in nematic films\nof submicron thickness is (re)examined by extending our previous work\n[Manyuhina et al EPL, 92, 16005 (2010)] to hybrid aligned nematics. We identify\nthe upper threshold for the formation of stripes and compare our results with\nexperimental observations. We find that the wavelength and the amplitude of the\nin-plane director undulations can be related to the small but finite azimuthal\nanchoring. Within a simplified model we analyse the possibility of non-planar\nbase state below the Barbero-Barberi critical thickness."
    },
    {
        "anchor": "Simulation of phase transitions in highly asymmetric fluid mixtures: We present a novel method for the accurate numerical determination of the\nphase behavior of fluid mixtures having large particle size asymmetries. By\nincorporating the recently developed geometric cluster algorithm within a\nrestricted Gibbs ensemble, we are able to probe directly the density and\nconcentration fluctuations that drive phase transitions, but that are\ninaccessible to conventional simulation algorithms. We develop a finite-size\nscaling theory that relates these density fluctuations to those of the\ngrand-canonical ensemble, thereby enabling accurate location of critical points\nand coexistence curves of multicomponent fluids. Several illustrative examples\nare presented.",
        "positive": "Effect of anisotropic diffusion on spinodal decomposition: We study the phase transition dynamics of a fluid system in which the\nparticles diffuse anisotropically in space. The motivation to study such a\nsituation is provided by systems of interacting magnetic colloidal particles\nsubject to the Lorentz force. The Smoluchowski equation for the many-particle\nprobability distribution then aquires an anisotropic diffusion tensor. We show\nthat anisotropic diffusion results in qualitatively different dynamics of\nspinodal decomposition compared to the isotropic case. Using the method of\ndynamical density functional theory, we predict that the intermediate-stage\ndecomposition dynamics are slowed down significantly by anisotropy; the\ncoupling between different Fourier modes is strongly reduced. Numerical\ncalculations are performed for a model (Yukawa) fluid that exhibits gas-liquid\nphase separation."
    },
    {
        "anchor": "Entanglement and weak interaction driven mobility of small molecules in\n  polymer networks: Diffusive transport of small molecules within the internal structures of\nbiological and synthetic material systems is complex because the crowded\nenvironment presents chemical and physical barriers to mobility. We explored\nthis mobility using a synthetic experimental system of small dye molecules\ndiffusing within a polymer network at short time scales. We find that the\ndiffusion of inert molecules is inhibited by the presence of the polymers.\nCounter-intuitively, small, hydrophobic molecules display smaller reduction in\nmobility and also able to diffuse faster through the system by leveraging\ncrowding specific parameters. We explained this phenomenon by developing a de\nnovo model and using these results, we hypothesized that non-specific\nhydrophobic interactions between the molecules and polymer chains could\nlocalize the molecules into compartments of overlapped and entangled chains\nwhere they experience microviscosity, rather than macroviscosity. We introduced\na characteristic interaction time parameter to quantitatively explain\nexperimental results in the light of frictional effects and molecular\ninteractions. Our model is in good agreement with the experimental results and\nallowed us to classify molecules into two different mobility categories solely\nbased on interaction. By changing the surface group, polymer molecular weight,\nand by adding salt to the medium, we could further modulate the mobility and\nmean square displacements of interacting molecules. Our work has implications\nin understanding intracellular diffusive transport in microtubule networks and\nother systems with macromolecular crowding and could lead to transport\nenhancement in synthetic polymer systems.",
        "positive": "On Local Kirigami Mechanics I: Isometric Conical Solutions: Over the past decade, kirigami--the Japanese art of paper cutting--has been\nplaying an increasing role in the emerging field of mechanical metamaterials\nand a myriad of other mechanical applications. Nonetheless, a deep\nunderstanding of the mathematics and mechanics of kirigami structures is yet to\nbe achieved in order to unlock their full potential to pioneer more advanced\napplications in the field. In this work, we study the most fundamental\ngeometric building block of kirigami: a thin sheet with a single cut. We\nconsider a reduced two-dimensional plate model of a circular thin disk with a\nradial slit and investigate its deformation following the opening of the slit\nand the rotation of its lips. In the isometric limit--as the thickness of the\ndisk approaches zero--the elastic energy has no stretching contribution and the\nthin sheet takes a conical shape known as the e-cone. We solve the\npost-buckling problem for the e-cone in the geometrically nonlinear setting\nassuming a Saint Venant-Kirchhoff constitutive plate model; we find closed-form\nexpressions for the stress fields and show the geometry of the e-cone to be\ngoverned by the spherical elastica problem. This allows us to fully map out the\nspace of solutions and investigate the stability of the post-buckled e-cone\nproblem assuming mirror symmetric boundary conditions on the rotation of the\nlips on the open slit."
    },
    {
        "anchor": "Boson-peak vibrational modes in glasses feature hybridized phononic and\n  quasilocalized excitations: A hallmark of structural glasses and other disordered solids is the emergence\nof excess low-frequency vibrations, on top of the Debye spectrum $D_{\\rm\nDebye}(\\omega)$ of phonons ($\\omega$ denotes the vibrational frequency), which\nexist in any solid whose Hamiltonian is translationally invariant. These excess\nvibrations -- a signature of which is a THz peak in the reduced density of\nstates $D(\\omega)/D_{\\rm Debye}(\\omega)$, known as the boson peak -- have\nresisted a complete theoretical understanding for decades. Here, we provide\ndirect numerical evidence that vibrations near the boson peak consist of\nhybridizations of phonons with many quasilocalized excitations, the latter were\nrecently shown to generically populate the low-frequency tail of the\nvibrational spectra of structural glasses quenched from a melt and of\ndisordered crystals. Our results suggest that quasilocalized excitations exist\nup to and in the vicinity of the boson-peak frequency, and hence constitute\nfundamental building blocks of the excess vibrational modes in glasses.",
        "positive": "Anomalous Polymer Dynamics Is Non-Markovian: Memory Effects and The\n  Generalized Langevin Equation Formulation: Any first course on polymer physics teaches that the dynamics of a tagged\nmonomer of a polymer is anomalously subdiffusive, i.e., the mean-square\ndisplacement of a tagged monomer increases as $t^\\alpha$ for some $\\alpha<1$\nuntil the terminal relaxation time $\\tau$ of the polymer. Beyond time $\\tau$\nthe motion of the tagged monomer becomes diffusive. Classical examples of\nanomalous dynamics in polymer physics are single polymeric systems, such as\nphantom Rouse, self-avoiding Rouse, self-avoiding Zimm, reptation,\ntranslocation through a narrow pore in a membrane, and many-polymeric systems\nsuch as polymer melts. In this pedagogical paper I report that all these\ninstances of anomalous dynamics in polymeric systems are robustly characterized\nby power-law memory kernels within a {\\it unified} Generalized Langevin\nEquation (GLE) scheme, and therefore, are non-Markovian. The exponents of the\npower-law memory kernels are related to the relaxation response of the polymers\nto local strains, and are derived from the equilibrium statistical physics of\npolymers. The anomalous dynamics of a tagged monomer of a polymer in these\nsystems is then reproduced from the power-law memory kernels of the GLE via the\nfluctuation-dissipation theorem (FDT). Using this GLE formulation I further\nshow that the characteristics of the drifts caused by a (weak) applied field on\nthese polymeric systems are also obtained from the corresponding memory\nkernels."
    },
    {
        "anchor": "Active Phases for Particles on Resource Landscapes: We introduce an active matter model composed of sterically interacting\nparticles which absorb resources from a substrate and move in response to\nresource gradients. For varied ratios of absorption rate to substrate recovery\nrate, we find a variety of phases including periodic waves, partial clustering,\nstochastic motion, and a frozen state. If passive particles are added, they can\nform crystalline clusters in an active fluid. This model could be implemented\nusing colloidal systems on feedback landscapes and can provide a soft matter\nrealization of excitable media and ecological systems.",
        "positive": "Photoredox Processes in the Aggregation and Gelation of\n  Electron-responsive Supramolecular Polymers Based on Viologens: Viologen-based ditopic bis-pyridinyl-triazole bidentate ligands self-assemble\nin the presence of palladium ions into supramolecular polymers whose structure\nis imposed by the directed formation of coordination bonds. Light-irradiation\nof these electron-responsive supramolecular materials triggers a photo-induced\nelectron transfer yielding isolated {\\pi}-radicals and dimers of radicals. The\nphotoreduction events and the associated dimerization steps trigger a\nlarge-scale reorganization occurring within the supramolecular network yielding\naggregates or gels depending on the irradiation conditions (power, duration).\nDetailed electrochemical, spectro-electrochemical and photochemical analyses\nwere conducted to understand the mechanisms at stakes in these light-induced\naggregation and gelation."
    },
    {
        "anchor": "Macro-scale Topology Optimization for Controlling Internal Shear Stress\n  in a Porous Scaffold Bioreactor: Shear stress is an important physical factor that regulates proliferation,\nmigration and morphogenesis. In particular, the homeostasis of blood vessels is\ndependent on shear stress. To mimic this process ex vivo, efforts have been\nmade to seed scaffolds with vascular and other cell types in the presence of\ngrowth factors and under pulsatile flow conditions. However, the resulting\nbioreactors lack information on shear stress and flow distributions within the\nscaffold. Consequently, it is difficult to interpret the effects of shear\nstress on cell function. Such knowledge would enable researchers to improve\nupon cell culture protocols. Recent work has focused on optimizing the\nmicrostructural parameters of the scaffold to fine tune the shear stress. In\nthis study, we have adopted a different approach whereby flows are redirected\nthroughout the bioreactor along channels patterned in the porous scaffold to\nyield shear stress distributions that are optimized for uniformity centered on\na target value. A topology optimization algorithm coupled to computational\nfluid dynamics simulations was devised to this end. The channel topology in the\nporous scaffold was varied using a combination of genetic algorithm and fuzzy\nlogic. The method is validated by experiments using magnetic resonance imaging\n(MRI) readouts of the flow field.",
        "positive": "Evidence that self-similar microrheology of highly entangled polymeric\n  solutions scales robustly with, and is tunable by, polymer concentration: We report observations of a remarkable scaling behavior with respect to\nconcentration in the passive microbead rheology of two highly entangled\npolymeric solutions, polyethylene oxide (PEO) and hyaluronic acid (HA). This\nbehavior was reported previously [Hill et al., PLOS ONE (2014)] for human lung\nmucus, a complex biological hydrogel, motivating the current study for\nsynthetic polymeric solutions PEO and HA. The strategy is to identify, and\nfocus within, a wide range of lag times ${\\tau}$ for which passive micron\ndiameter beads exhibit self-similar (fractional, power law)\nmean-squared-displacement (MSD) statistics. For lung mucus, PEO at three\ndifferent molecular weights (Mw), and HA at one Mw, we find ensemble-averaged\nMSDs of the form ${\\langle}{\\Delta}r^{2}({\\tau}){\\rangle} =\n4D_{\\alpha}{\\tau}^{\\alpha}$, all within a common band, [1/60 sec, 3 sec], of\nlag times ${\\tau}$. We employ the MSD power law parameters\n$(D_{\\alpha},{\\alpha})$ to classify each polymeric solution over a range of\nhighly entangled concentrations. By the generalized Stokes-Einstein relation,\npower law MSD implies power law elastic $G'({\\omega})$ and viscous\n$G''({\\omega})$ moduli for frequencies $1/{\\tau}$, [0.33 sec$^{-1}$, 60\nsec$^{-1}$]. A natural question surrounds the polymeric properties that dictate\n$D_{\\alpha}$ and ${\\alpha}$, e.g. polymer concentration c, Mw, and stiffness\n(persistence length). In [Hill et al., PLOS ONE (2014)], we showed the MSD\nexponent ${\\alpha}$ varies linearly, while the pre-factor $D_{\\alpha}$ varies\nexponentially, with concentration, i.e. the semi-log plot,\n$(log(D_{\\alpha}),{\\alpha})(c)$ of the classifier data is collinear. Here we\nshow the same result for three distinct Mw PEO and HA at a single Mw. Future\nstudies are required to explore the generality of these results for polymeric\nsolutions, and to understand this scaling behavior with polymer concentration."
    },
    {
        "anchor": "Particle Ice Front Interaction - The Brownian Ratchet Model: We treat the problem of particle pushing by growing ice as a free diffusion\nnear a wall that moves with discrete steps. When the particle diffuse away from\nthe surface the surface can grow, blocking the particle from going back.\nElementary calculations of the model reproduce established results for the\ncritical velocity $v_c$ for particle engulfment: $v_c\\sim 1/r$ for large\nparticles and $v_c\\sim$ Const for small particles, $r$ being the particle's\nradius. Using our model we calculate the dragging distance of the particle by\ntreating the pushing as a sequence of growing steps by the surface, each\nenabled by the particle's diffusion away. Eventually the particle is engulfed\nby ice growing around it when a rare event of long diffusion time away from the\nsurface occurs. By calculating numerically the statistics of the diffusion\ntimes from the surface and therefore the probability for a such a rare event we\ncalculate the total dragging time and distance $L$ of the particle by the ice\nfront to be $L\\sim\\exp[1/(vr)]$ where $v$ is the freezing velocity. This\nrelation for $L$ is confirmed by ours and others experiments. The distance $L$\nprovides a length scale for pattern formation during phase transition in\ncolloidal suspensions, such as ice lenses and lamellae structures by freeze\ncasting. Data from the literature for ice lenses thickness and lamellae spacing\nduring freeze casting agree with our prediction for the relation of the\ndistance $L$. These results lead us to conjecture that lamellae formation is\ndominated by their lateral growth which pushes and concentrates the particles\nbetween them.",
        "positive": "Capillary Bridge Formation and Breakage: A Test to Characterize\n  Antiadhesive Surfaces: In order to characterize very weak adhesive surfaces, we have developed a\nquantitative test inspired by the Johnson, Kendall, and Roberts adhesion test\nfor soft adhesives, which relies on the formation and then the rupture of a\ncapillary bridge between the surface to be tested and a liquid bath. Both the\nshape and the kinetics of breakage of the capillary bridge for various coatings\nput into contact with liquids of various viscosities and surface tensions have\nbeen studied. Several pull off regimes can be distinguished. For low pull off\nvelocities, a quasi-static regime is observed, well described by capillary\nequations and sensitive to the hysteresis of the contact angle of the fluid on\nthe coating. Above a critical pull off velocity that depends on the fluid\nviscosity, a dynamic regime is observed, characterized by the formation of a\nflat pancake of fluid on the coating that recedes more slowly than the\ncapillary bridge itself. After the breakage of the capillary bridge, a small\ndrop can remain attached to the surface. The volume of this drop depends on the\ndynamical regime and is strongly affected by very small differences between the\ncoatings. The aptitude of this test in characterizing very weakly adhesive\nsurfaces is exemplified by a comparison between three different perfluorinated\ncoatings."
    },
    {
        "anchor": "How short-ranged electrostatics controls the chromatin structure on much\n  larger scales: We propose that the degree of sweeling of the 30nm chromatin fiber (a\n\"measure\" of its transcriptional activity) is mainly determined by the\nshort-ranged electrostatical interaction between different sections of the\n\"folded\" DNA chain. These sections constitute only a small fraction of the\nchain and they are located close to the entry-exit points of the DNA chain at\nthe nucleosome core particles. We present a model that allows to estimate the\ndegree of swelling of chromatin fibers as a function of salt concentration,\ncharge density of the strands etc. Different mechanisms by which the state of\nchromatin can be controlled in vitro and in vivo are discussed.",
        "positive": "Short range attraction between two similarly charged silica surfaces: Using an Atomic Force Microscope (AFM) we measure the interaction between two\nidentically charged silica surfaces in the presence of saline solution. For\npure NaCl the interaction is always repulsive. Upon addition of cobalt hexamine\nions, [Co(NH3)6]+3, the repulsion is gradually suppressed and a pronounced\nattraction develops at distances much shorter than the screening length. Higher\nconcentrations of cobalt hexamine turn the attraction back into repulsion.\nMeasurements of surface charge renormalization by the three valent cations\nprovide their surface density and their association constant to the negatively\ncharged silica surface. These estimates exclude interaction between two\ncondensed Wigner crystals as an explanation for the attraction."
    },
    {
        "anchor": "Emergent SO(3) Symmetry of the Frictionless Shear Jamming Transition: We study the shear jamming of athermal frictionless soft spheres, and find\nthat in the thermodynamic limit, a shear-jammed state exists with different\nelastic properties from the isotropically-jammed state. For example,\nshear-jammed states can have a non-zero residual shear stress in the\nthermodynamic limit that arises from long-range stress-stress correlations. As\na result, the ratio of the shear and bulk moduli, which in isotropically-jammed\nsystems vanishes as the jamming transition is approached from above, instead\napproaches a constant. Despite these striking differences, we argue that in a\ndeeper sense, the shear jamming and isotropic jamming transitions actually have\nthe same symmetry, and that the differences can be fully understood by rotating\nthe six-dimensional basis of the elastic modulus tensor.",
        "positive": "Collapse transition in polymer models with multiple monomers per site\n  and multiple bonds per edge: We present results from extensive Monte Carlo simulations of polymer models\nwhere each lattice site can be visited by up to $K$ monomers and no restriction\nis imposed on the number of bonds on each lattice edge. These \\textit{multiple\nmonomer per site} (MMS) models are investigated on the square and cubic\nlattices, for $K=2$ and $K=3$, by associating Boltzmann weights $\\omega_0=1$,\n$\\omega_1=e^{\\beta_1}$ and $\\omega_2=e^{\\beta_2}$ to sites visited by 1, 2 and\n3 monomers, respectively. Two versions of the MMS models are considered for\nwhich immediate reversals of the walks are allowed (RA) or forbidden (RF). In\ncontrast to previous simulations of these models, we find the same\nthermodynamic behavior for both RA and RF versions. In three-dimensions, the\nphase diagrams - in space $\\beta_2 \\times \\beta_1$ - are featured by coil and\nglobule phases separated by a line of $\\Theta$ points, as thoroughly\ndemonstrated by the metric $\\nu_t$, crossover $\\phi_t$ and entropic $\\gamma_t$\nexponents. The existence of the $\\Theta$-lines is also confirmed by the second\nvirial coefficient. This shows that no discontinuous collapse transition exists\nin these models, in contrast to previous claims based on a weak bimodality\nobserved in some distributions, which indeed exists in a narrow region very\nclose to the $\\Theta$-line when $\\beta_1 < 0$. Interestingly, in\ntwo-dimensions, only a crossover is found between the coil and globule phases."
    },
    {
        "anchor": "Structural Order for One-Scale and Two-Scale Potentials: We perform molecular dynamics simulations to investigate the relationship\nbetween structural order and water-like dynamic and thermodynamic anomalies in\nspherically-symmetric potentials having either one or two characteristic length\nscales. %The first potential has only one length scale which is the diameter of\nthe ramp %without the hard core, and the second potential has two length\nscales: one is the %diameter of a ramp(softcore) and another one is the\ndiameter of a %hard core with a ratio of 1.76. Structural order is\ncharacterized by translational and orientational order parameters. %analogous\nto those used in previous cases for water and %silica.Only the two-scale ramp\npotential exhibits properties %remarkably similar to those found for water and\nsilica regarding the %relationship between structural order, dynamic anomalies,\nand thermodynamic %anomalies. We find that (i) dynamic and thermodynamic\nanomalies exist for both one-scale and two-scale ramp potentials, and (ii)\nwater-like structural order anomalies exist only for the two-scale ramp\npotential. Our findings suggest that the water-like relationship between\nstructural order and anomalies is related to the presence of two different\nlength scales in the potential.",
        "positive": "Structural properties of dense hard spheres near random close packing: We numerically study structural properties of mechanically stable packings of\nhard spheres (HS), in a wide range of packing fractions $0.53 \\le \\phi \\le\n0.72$. Detailed structural information is obtained from the analysis of\norientational order parameters, which clearly reveals a disorder-order phase\ntransition at the random close packing (RCP) density, $\\phi_{\\rm c} \\simeq\n0.64$. Above $\\phi_{\\rm c}$ the crystalline nuclei form 3D-like clusters, which\nupon further desification, transform into alternating planar-like layers. We\nalso find that particles with icosahedral symmetry survive only in a narrow\ndensity range in the vicinity of the RCP transition."
    },
    {
        "anchor": "Topological phonon modes and their role in dynamic instability of\n  microtubules: Microtubules (MTs) are self-assembled hollow protein tubes playing important\nfunctions in live cells. Their building block is a protein called tubulin,\nwhich self-assembles in a particulate 2 dimensional lattice. We study the\nvibrational modes of this lattice and find Dirac points in the phonon spectrum.\nWe discuss a splitting of the Dirac points that leads to phonon bands with\nnonzero Chern numbers, signaling the existence of topological vibrational modes\nlocalized at MTs edges, which we indeed observe after explicit calculations.\nSince these modes are robust against the large changes occurring at the edges\nduring the dynamic cycle of the MTs, we can build a simple mechanical model to\nillustrate how they would participate in this phenomenon.",
        "positive": "Hydrophobic droplets in amphiphilic bilayers: a coarse-grained\n  mean-field theory study: Hydrophobic molecules such as oils and certain drugs can be encapsulated\nbetween the two leaflets of an amphiphilic bilayer in both lipid and polymer\nsystems. We investigate the case where the hydrophobic molecules are\nincompatible with the amphiphile tails and so form droplets. Using a\ncoarse-grained mean-field model (self-consistent field theory, or SCFT), we\nfind that droplets of a wide range of sizes have the same characteristic lens\nshape, and explain this result in terms of simple capillarity arguments,\nconsistent with the measured variations of surface concentrations of amphiphile\nin the bilayer and in the monolayers that cover the droplet. We study the\neffect of the strength chi_BO of the repulsion between the hydrophobic liquid\nand the amphiphile tails on the droplet shape, and find a gradual flattening of\nthe droplet as chi_BO is reduced. The droplet remains at least metastable even\nat very low values of chi_BO. This is in contrast to the behavior as the length\nof the hydrophobic molecules is varied. Specifically, if these molecules are at\nleast as long as the amphiphile tails, increasing their length further is found\nto have little effect on the droplet shape, while reducing their length below\nthis value quickly causes the droplet to become unstable."
    },
    {
        "anchor": "Elasto-plastic response of reversibly crosslinked biopolymer bundles: We study the response of F-actin bundles to driving forces through a simple\nanalytical model. We consider two filaments connected by reversibly bound\ncrosslinks and driven by an external force. Two failure modes under load can be\ndefined. \\textit{Brittle failure} is observed when crosslinks suddenly and\ncollectively unbind, leading to catastrophic loss of bundle integrity. During\n\\textit{ductile failure}, on the other hand, bundle integrity is maintained,\nhowever at the cost of crosslink reorganization and defect formation. We\npresent phase diagrams for the onset of failure, highlighting the importance of\nthe crosslink stiffness for these processes. Crossing the phase boundaries,\nforce-deflection curves display (frequency-dependent) hysteresis loops,\nreflecting the first-order character of the failure processes. We evidence how\nthe introduction of defects can lead to complex elasto-plastic relaxation\nprocesses, once the force is switched off. Depending on, both, the time-scale\nfor defect motion as well as the crosslink stiffness, bundles can remain in a\nquasi-permanent plastically deformed state for a very long time.",
        "positive": "Direct Measurement of the Surface Tension of Nanobubbles: It is shown that when the nanobubble contact line is pinned to a penetrating\ntip the interface behaves like a Hookean spring with spring constant\nproportional to the nanobubble surface tension. Atomic force microscope (AFM)\ndata for several nanobubbles and solutions are analysed and yield surface\ntensions in the range 0.04--0.05 N/m (compared to 0.072 N/m for saturated\nwater), and supersaturation ratios in the range 2--5. These are the first\ndirect measurements of the surface tension of a supersaturated air-water\ninterface. The results are consistent with recent theories of nanobubble size\nand stability, and with computer simulations of the surface tension of a\nsupersaturated solution."
    },
    {
        "anchor": "Errors in energy landscapes measured with particle tracking: Tracking Brownian particles is often employed to map the energy landscape\nthey explore. Such measurements have been exploited to study many biological\nprocesses and interactions in soft materials. Yet, video tracking is\nirremediably contaminated by localization errors originating from two imaging\nartifacts: the \"static\" errors come from signal noise, and the \"dynamic\" errors\narise from the motion blur due to finite frame acquisition time. We show that\nthese errors result in systematic and non-trivial biases in the measured energy\nlandscapes. We derive a relationship between the true and the measured\npotential that elucidates, among other aberrations, the presence of false\ndouble-well minima in the apparent potentials reported in recent studies. We\nfurther assess several canonical trapping and pair-interaction potentials, by\nusing our analytically derived results and Brownian dynamics simulations. In\nparticular, we show that the apparent spring stiffness of harmonic potentials\n(such as optical traps) is increased by dynamic errors, but decreased by static\nerrors. Our formula allows for the development of efficient corrections\nschemes, which we also present in this paper.",
        "positive": "Charging changes contact composition in binary sphere packings: Equal volume mixtures of small and large polytetrafluorethylene (PTFE)\nspheres are shaken in an atmosphere of controlled humidity which allows to also\ncontrol their tribo-charging. We find that the contact numbers are\ncharge-dependent: as the charge density of the beads increases, the number of\nsame-type contacts decreases and the number of opposite-type contacts\nincreases. This change is not caused by a global segregation of the sample.\nHence, tribo-charging can be a way to tune the local composition of a granular\nmaterial."
    },
    {
        "anchor": "Arching in tapped deposits of hard disks: We simulate the tapping of a bed of hard disks in a rectangular box by using\na pseudo dynamic algorithm. In these simulations, arches are unambiguously\ndefined and we can analyze their properties as a function of the tapping\namplitud. We find that an order--disorder transition occurs within a narrow\nrange of tapping amplitudes as it has been seen by others. Arches are always\npresent in the system althought they exhibit regular shapes in the ordered\nregime. Interestingly, an increase in the number of arches does not always\ncorrespond to a reduction in the packing fraction. This is in contrast with\nwhat is found in three-dimensional systems.",
        "positive": "Optothermal evolution of active colloidal matter in defocused laser trap: Optothermal interaction of active colloidal matter can facilitate\nenvironmental cues which can influence the dynamics of active soft matter\nsystems. The optically induced thermal effect can be harnessed to study\nnon-equilibrium thermodynamics as well as applied to self-propel colloids and\nform assemblies. In this work, we employ a defocused laser trap to form\nself-evolving colloidal active matter. The optothermal interaction of the\nactive colloids in both focused and defocused optical trap has been\ninvestigated to ascertain their thermophoretic behavior, which shows a\nlong-range attraction and a short-range repulsion between the colloids. The\noptical gradient field enabled attraction and the short-range repulsion between\nthe active colloids have been harnessed to form re-configurable dynamic\nassembly. Additionally, the assembly undergoes self-evolution as a new colloid\njoins the structure. Further, we show that the incident polarization state of\nthe optical field can be employed as a parameter to modulate the structural\norientation of the active colloids. The simple defocused optical field-enabled\nassembly can serve as a model to understand the collective dynamics of active\nmatter systems, and can be harnessed as re-configurable microscopic engine."
    },
    {
        "anchor": "Photo-activated dynamic isomerization induced large density changes in\n  liquid crystal polymers: A molecular dynamics study: Recent experimental results [Liu and Broer, Nat. Commun. 6 8334 (2015)]\nreveal that light-responsive azo-doped liquid crystal polymers under\ndual-wavelength illumination exhibit a significant reduction in density. This\nreduction in density was attributed to dynamic trans-cis-trans isomerization\ncycles. The light-induced isomerization kinetics suggest that the fraction of\nisomers undergoing dynamic isomerization increases with the light sources'\nintensity. However, experiments have shown that such an increase in intensity\ndoes not result in a monotonic decrease in density. Further, it was observed\nthat there exists an optimal combination of the intensities of the\ndual-wavelength illumination that results in a maximum density reduction. The\nexact reason for the existence of such an optimal combination remains elusive.\nIn this work, we have performed atomistic simulations to confirm the hypothesis\nthat the density reduction is caused by the dynamic trans-cis-trans\nisomerization cycles. Subsequently, the atomistic simulations are used to\ndecipher the underlying physics responsible for the counter-intuitive relation\nbetween density reduction and intensities. Intensity variations are simulated\nby varying the forward and backward isomerization probabilities. The\nsimulations show that an optimal combination of these two probabilities will\nexhibit a maximum density reduction corroborating experimental observations.\nConsequently, we discovered that a specific frequency of the dynamic\ntrans-cis-trans isomerization cycles would induce maximum distortion in the\npolymer network resulting in significant density reduction.",
        "positive": "Collective Behavior of Crowded Drops in Microfluidic Systems: Droplet microfluidics, in which micro-droplets serve as individual reactors,\nhas enabled a wide range of high-throughput biochemical processes. Unlike solid\nwells typically used in current biochemical assays, droplets are subject to\ninstability and can undergo breakup, especially under fast flow conditions.\nAlthough the physics of single drops has been studied extensively, the flow of\ncrowded drops or concentrated emulsions, where droplet volume fraction exceeds\n80 percent, is relatively unexplored in microfluidics. In this article and the\nrelated invited lecture from the 74th Annual Meeting of the American Physical\nSociety's Division of Fluid Dynamics, we describe the collective behavior of\ndrops in a concentrated emulsion by tracking the dynamics and the fate of\nindividual drops within the emulsion. At the slow flow limit of the\nconcentrated emulsion, we observe an unexpected order, where the velocity of\nindividual drops in the emulsion exhibits spatiotemporal periodicity. As the\nflow rate increases, the emulsion transitions from a solid-like to a\nliquid-like material, and the spatiotemporal order in the flow is lost. At the\nfast flow limit, droplet breakup starts to occur. We show that droplet breakup\nwithin the emulsion follows a probability distribution, in stark contrast to\nthe deterministic behavior in classical single-drop studies. In addition to\ncapillary number and viscosity ratio, break-up probability is governed by a\nconfinement factor that measures drop size relative to a characteristic channel\nlength. The breakup probability arises from the time-varying packing\nconfiguration of the drops. Finally, we discuss recent progress in computation\nmethods for recapitulating the flow of concentrated emulsions."
    },
    {
        "anchor": "Hydrodynamics is Needed to Explain Propulsion in Chemophoretic Colloidal\n  Rafts: Active particles driven by a chemical reaction are the subject of intense\nresearch to date due to their rich physics, being intrinsically far from\nequilibrium, and their multiple technological applications. Recent attention in\nthe field is now shifting towards exploring the fascinating dynamics of mixture\nof active and passive systems. Here we realize active colloidal rafts, composed\nof a single catalytic particle encircled by several shells of passive\nmicrospheres assembled via light activated, chemophoretic flow. We show that\nconsidering only diffusiophoresis can explain the cluster kinetics but not the\ncluster propulsion behavior. Thus, using the Lorenz reciprocal theorem, we show\nthat propulsion emerges by considering hydrodynamics via the diffusioosmotic\nanswer of the substrate to the generated chemophoretic flow. While\ndiffusioosmotic flows are often relegate to a secondary role, our work\ndemonstrates their importance to understand the rich physics of active\ncatalytic systems.",
        "positive": "Determination of the positions and orientations of concentrated rod-like\n  colloids from 3D microscopy data: Confocal microscopy in combination with real-space particle tracking has\nproven to be a powerful tool in scientific fields such as soft matter physics,\nmaterials science and cell biology. However, 3D tracking of anisotropic\nparticles in concentrated phases remains not as optimized compared to\nalgorithms for spherical particles. To address this problem, we developed a new\nparticle-fitting algorithm that can extract the positions and orientations of\nfluorescent rod-like particles from three dimensional confocal microscopy data\nstacks, even when the fluorescent signals of the particles overlap\nconsiderably. We demonstrate that our algorithm correctly identifies all five\ncoordinates of uniaxial particles in both a concentrated disordered phase and a\nliquid-crystalline smectic-B phase. Apart from confocal microscopy images, we\nalso demonstrate that the algorithm can be used to identify nanorods in 3D\nelectron tomography reconstructions. Lastly, we determined the accuracy of the\nalgorithm using both simulated and experimental confocal microscopy data-stacks\nof diffusing silica rods in a dilute suspension. This novel particle-fitting\nalgorithm allows for the study of structure and dynamics in both dilute and\ndense liquid-crystalline phases (such as nematic, smectic and crystalline\nphases) as well as the study of the glass transition of rod-like particles in\nthree dimensions on the single particle level."
    },
    {
        "anchor": "Helium adsorption in silica aerogel near the liquid-vapor critical point: We have investigated the adsorption and desorption of helium near its\nliquid-vapor critical point in silica aerogels with porosities between 95% and\n98%. We used a capacitive measurement technique which allowed us to probe the\nhelium density inside the aerogel directly, even though the samples were\nsurrounded by bulk helium. The aerogel's very low thermal conductivity resulted\nin long equilibration times so we monitored the pressure and the helium\ndensity, both inside the aerogel and in the surrounding bulk, and waited at\neach point until all had stabilized. Our measurements were made at temperatures\nfar from the critical point, where a well defined liquid-vapor interface\nexists, and at temperatures up to the bulk critical point. Hysteresis between\nadsorption and desorption isotherms persisted to temperatures close to the\nliquid-vapor critical point and there was no sign of an equilibrium\nliquid-vapor transition once the hysteresis disappeared. Many features of our\nisotherms can be described in terms of capillary condensation, although this\npicture becomes less applicable as the liquid-vapor critical point is\napproached and it is unclear how it can be applied to aerogels, whose tenuous\nstructure includes a wide range of length scales.",
        "positive": "The Boson peak in supercooled water: We perform extensive molecular dynamics simulations of the TIP4P/2005 model\nof water to investigate the origin of the Boson peak reported in experiments on\nsupercooled water in nanoconfined pores, and in hydration water around\nproteins. We find that the onset of the Boson peak in supercooled bulk water\ncoincides with the crossover to a predominantly low-density-like liquid below\nthe Widom line $T_W$. The frequency and onset temperature of the Boson peak in\nour simulations of bulk water agree well with the results from experiments on\nnanoconfined water. Our results suggest that the Boson peak in water is not an\nexclusive effect of confinement. We further find that, similar to other\nglass-forming liquids, the vibrational modes corresponding to the Boson peak\nare spatially extended and are related to transverse phonons found in the\nparent crystal, here ice Ih."
    },
    {
        "anchor": "Elastic Properties of Confined Fluids from Molecular Modeling to\n  Ultrasonic Experiments on Porous Solids: Fluids confined in nanopores are ubiquitous in nature and technology. In\nrecent years, the interest in confined fluids has grown, driven by research on\nunconventional hydrocarbon resources -- shale gas and shale oil, much of which\nare confined in nanopores. When fluids are confined in nanopores, many of their\nproperties differ from those of the same fluid in the bulk. These properties\ninclude density, freezing point, transport coefficients, thermal expansion\ncoefficient, and elastic properties. The elastic moduli of a fluid confined in\nthe pores contribute to the overall elasticity of the fluid-saturated porous\nmedium and determine the speed at which elastic waves traverse through the\nmedium. Wave propagation in fluid-saturated porous media is pivotal for\ngeophysics, as elastic waves are used for characterization of formations and\nrock samples. In this paper, we present a comprehensive review of experimental\nworks on wave propagation in fluid-saturated nanoporous media, as well as\ntheoretical works focused on calculation of compressibility of fluids in\nconfinement. We discuss models that bridge the gap between experiments and\ntheory, revealing a number of open questions that are both fundamental and\napplied in nature. While some results were demonstrated both experimentally and\ntheoretically (e.g. the pressure dependence of compressibility of fluids),\nothers were theoretically predicted, but not verified in experiments (e.g.\nlinear scaling of modulus with the pore size). Therefore, there is a demand for\nthe combined experimental-modeling studies on porous samples with various\ncharacteristic pore sizes. The extension of molecular simulation studies from\nsimple model fluids to the more complex molecular fluids is another open area\nof practical interest.",
        "positive": "A Simple Model for the Deformation-Induced Relaxation of Glassy Polymers: Glassy polymers show strain hardening: at constant extensional load, their\nflow first accelerates, then arrests. Recent experiments have found this to be\naccompanied by a striking and unexplained dip in the segmental relaxation time.\nHere we explain such behavior by combining a minimal model of flow-induced\nliquefaction of a glass, with a description of the stress carried by strained\npolymers, creating a non-factorable interplay between aging and strain-induced\nrejuvenation. Under constant load, liquefaction of segmental motion permits\nstrong flow that creates polymer-borne stress. This slows the deformation\nenough for the segmental modes to re-vitrify, causing strain hardening."
    },
    {
        "anchor": "T4 DNA condensation in water-alcohol media: The process of compaction of high molecular weight DNA T4 is investigated\ndirectly in a AFM liquid cell. The AFM-images of globules formed by DNA\nmolecules in the result of compaction in water-alcohol environments at high\nizopropanol concentration (80%) are received; it is found that at intermediate\nconcentration of izopropanol (40-50%) the DNA molecules form partially\ncompacted formations in which the separate coils of macromolecules twist in\ntoroidal structures. It is shown using the technique of deconvolution of the\nAFM-images that the globule include only one closely packed DNA molecule. The\nmodel of DNA packing is proposed on the basis of AFM experiment.",
        "positive": "Controlled Fluidization, Mobility and Clogging in Obstacle Arrays Using\n  Periodic Perturbations: We show that the clogging susceptibility and flow of particles moving through\na random obstacle array can be controlled with a transverse or longitudinal ac\ndrive. The flow rate can vary over several orders of magnitude, and we find\nboth an optimal frequency and an optimal amplitude of driving that maximizes\nthe flow. For dense arrays, at low ac frequencies a heterogeneous creeping\nclogged phase appears in which rearrangements between different clogged\nconfigurations occur. At intermediate frequencies a high mobility fluidized\nstate forms, and at high frequencies the system reenters a heterogeneous frozen\nclogged state. These results provide a technique for optimizing flow through\nheterogeneous media that could also serve as the basis for a particle\nseparation method."
    },
    {
        "anchor": "A Gaussian theory for fluctuations in simple liquids: Assuming an effective quadratic Hamiltonian, we derive an approximate, linear\nstochastic equation of motion for the density-fluctuations in liquids, composed\nof overdamped Brownian particles. From this approach, time dependent two point\ncorrelation functions (such as the intermediate scattering function) are\nderived. We show that this correlation function is exact at short times, for\nany interaction and, in particular, for arbitrary external potentials so that\nit applies to confined systems. Furthermore, we discuss the relation of this\napproach to previous ones, such as dynamical density functional theory as well\nas the formally exact treatment. This approach, inspired by the well known\nLandau-Ginzburg Hamiltonians, and the corresponding \"Model B\" equation of\nmotion, may be seen as its microscopic version, containing information about\nthe details on the particle level.",
        "positive": "Extraction of the propulsive speed of catalytic nano- and micro-motors\n  under different motion dynamics: Motion of active particles, such as catalytic micro- and nano-motors, is\nusually characterized via either dynamic light scattering or optical\nmicroscopy. In both cases, speed of particles is obtained from the calculus of\nthe mean square displacement (MSD) and typically, the theoretical formula of\nthe MSD is derived from the motion equations of an active Brownian particle.\nOne of the most commonly reported parameters is the speed of the particle,\nusually attributed to its propulsion, and is widely used to compare the motion\nefficiency of catalytic motors. However, it is common to find different methods\nto compute this parameter, which are not equivalent approximations and do not\npossess the same physical meaning. Here, we review the standard methods of\nspeed analysis and focus on the errors that arise when analyzing the MSD of\nself-propelled particles. We analyze the errors from the computation of the\ninstantaneous speed, as well as the propulsive speed and diffusion coefficient\nthrough fittings to parabolic equations, and we propose a revised formula for\nthe motion analysis of catalytic particles moving with constant speed that can\nimprove the accuracy and the amount of information obtained from the MSD.\nMoreover, we emphasize the importance of spotting the presence of different\nmotion dynamics, such as particles with active angular speed or that move under\nthe presence of drift, and how the breaking of ergodicity can completely change\nthe analysis by considering particles with an exponentially decaying speed. In\nall cases, real data from enzymatically propelled micro-motors and simulations\nare used to back up the theories. Finally, we propose several analytical\napproaches and analyze limiting cases that will help to deal with these\nscenarios while still obtaining accurate results."
    },
    {
        "anchor": "Robust Folding of Elastic Origami: Self-folding origami, structures that are engineered flat to fold into\ntargeted, three-dimensional shapes, have many potential engineering\napplications. Though significant effort in recent years has been devoted to\ndesigning fold patterns that can achieve a variety of target shapes, recent\nwork has also made clear that many origami structures exhibit multiple folding\npathways, with a proliferation of geometric folding pathways as the origami\nstructure becomes complex. The competition between these pathways can lead to\nstructures that are programmed for one shape, yet fold incorrectly. To\ndisentangle the features that lead to misfolding, we introduce a model of\nself-folding origami that accounts for the finite stretching rigidity of the\norigami faces and allows the computation of energy landscapes that lead to\nmisfolding. We find that, in addition to the geometrical features of the\norigami, the finite elasticity of the nearly-flat origami configurations\nregulates the proliferation of potential misfolded states through a series of\nsaddle-node bifurcations. We apply our model to one of the most common origami\nmotifs, the symmetric \"bird's foot,\" a single vertex with four folds. We show\nthat though even a small error in programmed fold angles induces metastability\nin rigid origami, elasticity allows one to tune resilience to misfolding. In a\nmore complex design, the \"Randlett flapping bird,\" which has thousands of\npotential competing states, we further show that the number of actual observed\nminima is strongly determined by the structure's elasticity. In general, we\nshow that elastic origami with both stiffer folds and stiffer faces self-folds\nbetter.",
        "positive": "Molecular Dynamic study of model two-dimensional systems involving Janus\n  dumbbells and spherical particles: We have performed an extensive constant temperature Molecular Dynamics study\nof two-dimensional systems involving Janus dumbbells and spherical particles.\nJanus dumbbells have been modelled as two spheres, labeled 1 and 2, joined\ntogether via harmonic bonds. Sphere 1 of a selected Janus dumbbell attracts the\nspheres of the same kind on other Janus dumbbells, while the interactions\nbetween the pairs 1-1 and 1-2 were repulsive. On the other hand, the spherical\nparticles are attracted by centers 2 and repelled by the centers 1 of Janus\nparticles. We have shown that the structure of oriented phases that can be\nformed in the system depends on the bond length of Janus dumbbells and the\nratio of the number of spherical particles to the number of Janus dumbbells in\nthe system. The presence of spherical particles is necessary to develop\noriented phases. For the assumed model, the formation of oriented phases in the\nsystem depends on the concentration of spherical particles. Equal numbers of\nJanus and spherical particles create optimal conditions for the formation of\nlamellar phases."
    },
    {
        "anchor": "Auto-assemblies of Alpha-Cyclodextrin and Grafted Polysaccharides:\n  Crystal Structure and Specific Properties of the Platelets: Cyclodextrins (CD) are a family of oligosaccharides with a toroid shape,\nwhich exhibit a remarkable ability to include guest molecules in their internal\ncavity providing a hydrophobic environment for poorly soluble molecules.\nRecently new types of inclusions of alpha CD with alkyl grafted polysaccharide\nchains (pullulan, chitosan, dextran, amylopectin, chondroitin sulfate) have\nbeen prepared which are auto assembled into micro and nano platelets. We report\nin this paper an extensive investigation of platelets with different\ncompositions, including their reversible hydration (Thermo Gravimetric\nAnalysis), crystalline structure (Powder X Rays Diffraction), dimensions and\nshapes, (Scanning Electron Microscopy Field Emission Gun), thermal properties,\nsolubility and melting (Micro Differential Scanning Calorimetry). The\ncrystalline platelets exhibit layered structures intercalating the\npolysaccharide backbones and CD complexes hosting the grafted alkyl chains. The\nmonoclinic symmetry of columnar type crystals suggests a head to tail\narrangement of the CDs. The platelets have a preferentially hexagonal shape\nwith sharp edges, variable sizes, and thicknesses and sometimes show incomplete\nlayers (terraces). The crystal parameters change upon dehydration. Melting\ntemperatures of platelets in aqueous solutions exceeds 100 degree. Finally, we\ndiscuss the potential relation between the platelet structure and applications\nfor mucoadhesive devices.",
        "positive": "Non-Equilibrium Interaction Between Catalytic Colloids: Boundary\n  Conditions and Penetration Depth: Spherical colloids that catalyze the interconversion reaction $A\n\\leftrightharpoons B$ between solute molecules $A$ and $B$ whose concentration\nat infinity is maintained away from equilibrium effectively interact due to the\nnon-uniform fields of solute concentrations. We show that this long range $1/r$\ninteraction is suppressed via a mechanism that is superficially reminiscent but\nqualitatively very different from electrostatic screening: catalytic activity\ndrives the concentrations of solute molecules towards their equilibrium values\nand reduces the chemical imbalance that drives the interaction between the\ncolloids. The imposed non-equilibrium boundary conditions give rise to a\nvariety of geometry-dependent scenarios; while long-range interactions are\nsuppressed (except for a finite penetration depth) in the bulk of the colloid\nsolution in 3D, they can persist in quasi-2D geometry in which the colloids but\nnot the solutes are confined to a surface, resulting in the formation of\nclusters or Wigner crystals, depending on the sign of the interaction between\ncolloids."
    },
    {
        "anchor": "Purely hydrodynamic origin for swarming of swimming particles: Three-dimensional simulations with fully resolved hydrodynamics are performed\nto study the collective motion of model swimmers in confinement. We show that\ncertain swimming mechanisms can lead to traveling wave-like collective motion\neven without any direct alignment mechanism. It is also shown that by varying\nthe swimming mechanism, this collective motion can be suppressed, contrary to\nthe perception that hydrodynamic effects are completely screened at high volume\nfraction. From an analysis of bulk systems, it is shown that this traveling\nwave-like motion, which can be characterized as a pseudo-acoustic mode, is\nmainly due to the intrinsic swimming property of the particles.",
        "positive": "A dynamic density functional theory for particles in a flowing solvent: We present a dynamic density functional theory (dDFT) which takes into accou\nnt the advection of the particles by a flowing solvent. For potential flows we\ncan use the same closure as in the absence of solvent flow. The structure of\nthe resulting advected dDFT suggests that it could be used for non-potential\nflows as well. We apply this dDFT to Brownian particles (e.g., polymer coils)\nin a solvent flowing around a spherical obstacle (e.g., a colloid) and compare\nthe results with direct simulations of the underlying Brownian dynamics.\n  Although numerical limitations do not allow for an accurate quantitative\ncheck of the advected dDFT both show the same qualitative features. In contrast\nto previous works which neglected the deformation of the flow by the obstacle,\nwe find that the bow-wave in the density distribution of particles in front of\nthe obstacle as well as the wake behind it are reduced dramatically. As a\nconsequence the friction force exerted by the (polymer) particles on the\ncolloid can be reduced drastically."
    },
    {
        "anchor": "Correlation between structure and conductivity of stretched Nafion: We have used coarse-grained simulation methods to investigate the effect of\nstretching-induced structure orientation on the proton conductivity of\nNafion-like polyelectrolyte membranes. Recent experimental data on the\nmorphology of ionomers describe Nafion as an aggregation of polymeric backbone\nchains forming elongated objects embedded in a continuous ionic medium.\nUniaxial stretching of a recast Nafion film causes a preferential orientation\nof these objects in the direction of stretching. Our simulations of humid\nNafion show that this has a strong effect on the proton conductivity, which is\nenhanced along the stretching direction, while the conductivity perpendicular\nto the stretched polymer backbone is reduced. Stretching also causes the\nperfluorinated side chains to orient perpendicular to the stretching axis.\n  This in turn affects the distribution of water at low water contents. The\nwater forms a continuous network with narrow bridges between small water\nclusters absorbed in head-group multiplets.",
        "positive": "Understanding the movements of metal whiskers: Metal whiskers often grow across leads of electric equipment and electronic\npackage causing current leakage or short circuits and raising significant\nreliability issues. The nature of metal whiskers remains a mystery after\nseveral decades of research. In addition, metal whiskers exhibit a rather\nunusual dynamic property of relatively high amplitude movements under gentle\nair flow or, according to some testimonies, without obvious stimuli.\nUnderstanding the physics behind that motion would give additional insights\ninto the nature of metal whiskers. Here, we quantitatively analyze several\npossible mechanisms potentially responsible for the observed movements: (1)\nminute air currents, (2) Brownian motion due to random bombardments with the\nair molecules, (3) mechanically caused movements, such as (a) externally\ntransmitted vibrations of the sample, and (b) torque exerted due to material\npropagation along curved whiskers responsible for the whisker growth (similar\nto the known garden hose oscillations), (4) time dependent electric fields due\nto diffusion of ions across the metal surface, and (5) nonequilibrium electric\nfield configurations making it possible for {\\it some} whiskers to move. For\nall these scenarios we provide numerical estimates. Our conclusion is that the\nobserved movements are likely due to the minor air currents, intentional or\nill-controlled, and that external mechanical vibrations could force such\nmovements in a rather harsh environment or/and for whiskers with severe\nconstrictions. We argue that under non-steady state conditions, such as caused\nby changes in the external light intensity, some whiskers can exercise\nspontaneous oscillations."
    },
    {
        "anchor": "Depletion forces near curved surfaces: Based on density functional theory the influence of curvature on the\ndepletion potential of a single big hard sphere immersed in a fluid of small\nhard spheres with packing fraction \\eta_s either inside or outside of a hard\nspherical cavity of radius R_c is calculated. The relevant features of this\npotential are analyzed as function of \\eta_s and R_c. There is a very slow\nconvergence towards the flat wall limit R_c \\to \\infty. Our results allow us to\ndiscuss the strength of depletion forces acting near membranes both in normal\nand lateral directions and to make contact with recent experimental results.",
        "positive": "Enslaved Phase-Separation Fronts and Liesegang Pattern Formation: We show that an enslaved phase-separation front moving with diffusive speeds\nU = C T^(-1/2) can leave alternating domains of increasing size in their wake.\nWe find the size and spacing of these domains is identical to Liesegang\npatterns. For equal composition of the components we are able to predict the\nexact form of the pattern analytically. We also show that there is a critical\nvalue for C below which only two domains are formed. Our analytical predictions\nare verified by numerical simulations using a lattice Boltzmann method."
    },
    {
        "anchor": "The impact of the interfacial Kapitza resistance on colloidal\n  thermophoresis: Thermal gradients impart a force on colloidal particles pushing the colloids\ntowards cold or hot regions, a phenomenon called thermophoresis. Existing\ntheories describe thermophoresis by considering the local perturbation of the\nthermal field around the colloid. While these approaches incorporate\ninterfacial surface free energies, they have consistently ignored the impact of\nthe Kapitza resistance associated with the colloid-solvent interface. We\npropose a theoretical approach to include interfacial Kapitza resistance\neffects, and we test the new equations using non-equilibrium molecular dynamics\nsimulations. We demonstrate that the Kapitza resistance influences the local\nthermal field around a colloid, modifying the Soret coefficient. We conclude\nthat interfacial thermal conductance effects must be included to describe\nthermophoresis.",
        "positive": "Phase separation in mixtures of colloids and long ideal polymer coils: Colloidal suspensions with free polymer coils which are larger than the\ncolloidal particles are considered. The polymer-colloid interaction is modeled\nby an extension of the Asakura-Oosawa model. Phase separation occurs into\ndilute and dense fluid phases of colloidal particles when polymer is added. The\ncritical density of this transition tends to zero as the size of the polymer\ncoils diverges."
    },
    {
        "anchor": "Equilibrium and non-equilibrium concentration fluctuations in a critical\n  binary mixture: When a macroscopic concentration gradient is present across a binary mixture,\nlong-ranged non-equilibrium concentration fluctuations (NCF) appear as a\nconsequence of the coupling between the gradient and spontaneous equilibrium\nvelocity fluctuations. Long-ranged equilibrium concentration fluctuations (ECF)\nmay be also observed when the mixture is close to a critical point. Here we\nstudy the interplay between NCF and critical ECF in a near critical mixture\naniline/cyclohexane in the presence of a vertical concentration gradient. To\nthis aim, we exploit a commercial optical microscope and a simple, custom-made,\ntemperature-controlled cell to obtain simultaneous static and dynamic\nscattering information on the fluctuations. We first characterise the critical\nECF at fixed temperature $T$ above the upper critical solution temperature\n$T_{c}$, in the wide temperature range $T-T_{c}\\in[0.1,30]$ $^{o}$C. In this\nrange, we observe the expected critical scaling behaviour for both the\nscattering intensity and the mass diffusion coefficient and we determine the\ncritical exponents $\\gamma$, $\\nu$ and $\\eta$, which are found in agreement\nwith the 3D Ising values. We then study the system in the two-phase region\n($T<T_{c}$). In particular, we characterise the interplay between ECF and NCF\nwhen the mixture, initially at a temperature $T_{i}$, is rapidly brought to a\ntemperature $T_{f}>T_{i}$. During the transient, a vertical diffusive mass flux\nis present that causes the onset of NCF, whose amplitude vanishes with time, as\nthe flux goes to zero. We also study the time dependence of the equilibrium\nscattering intensity $I_{eq}$, of the crossover wave-vector $q_{co}$ and of the\ndiffusion coefficient $D$ during diffusion and find that all these quantities\nexhibit an exponential relaxation enslaved to the diffusive kinetics.",
        "positive": "Aging effects in simple models for glassy relaxation: Aging effects in the two-time correlation function and the response function\nafter a quench from a high temperature to some low temperature are considered\nfor a simple kinetic random energy model exhibiting stretched exponential\nrelaxation. Because the system reaches thermal equilibrium for long times after\nthe quench, all aging effect are of a transient nature. In particular, the\nviolations of the fluctuation-dissipation theorem are considered and it is\nfound that the relation between the response and the two-time correlation\nfunction depends on another function, the so-called asymmetry. This asymmetry\nvanishes in equilibrium but cannot be neglected in the aging regime. It is\nfound that plots of the integrated response versus the correlation function are\nnot applicable to quantify the violations of the fluctuation-dissipation\ntheorem in this particular model. This fact has its origin in the absence of a\nscaling form of the correlation."
    },
    {
        "anchor": "The Origin of Persistent Shear Stress in Supercooled Liquids: We show that the long time tail of the shear stress autocorrelation, whose\ngrowth at large supercooling is responsible for the apparent divergence of the\nshear viscosity, is a direct result of a residual shear stress in the\nstructures associated with the local potential minima. We argue that the\nessential mechanical transition experienced by a liquid on cooling occurs at a\ntemperature well above the glass transition temperature and corresponds to the\ncrossover from the high temperature liquid to the viscous liquid, the latter\ncharacterised by stress relaxation dominated by the residual stress. Following\non from this observation, as the density is decreased, the local potential\nminima become unable to sustain any persistent stress (and, hence, support a\nglass transition), in a manner that can be explicitly connected to the\ninteractions between atoms. The reported crossover implies an associated change\nin the mechanism of dissipation in liquids and, hence, raises the prospect of a\ncoherent microscopic treatment of nonlinear rheology and the relationship\nbetween self diffusion and viscosity in supercooled liquids.",
        "positive": "In-situ imaging of the three-dimensional shape of soft responsive\n  particles at fluid interfaces by atomic force microscopy: The reconfiguration of soft, deformable particles upon adsorption at the\ninterface between two fluids underpins many aspects of their dynamics and\ninteractions, ultimately controlling the macroscopic properties of particle\nmonolayers of relevance for materials, such as particle-stabilized emulsions\nand foams, and processes, e. g. particle-based lithography. In spite of its\nimportance, experimentally determining the three-dimensional shape of soft\nparticles at fluid interfaces with high resolution remains an elusive task. In\nthis work, we take poly(N-isopropylacrylamide) (pNIPAM) microgels as model soft\nparticles and demonstrate that their conformation at the interface between an\naqueous and an oil phase can be fully reconstructed by means of in-situ atomic\nforce microscopy (AFM) imaging. We show that imaging the particle topography\nfrom both sides of the interface allows one to characterize the in-plane\ndeformation of the particle under the action of interfacial tension and to\nvisualize the occurrence of asymmetric swelling in the two fluids.\nAdditionally, the technique enables investigating different fluid phases and\nparticle architectures, as well as studying in situ the effect of temperature\nvariations on particle conformation. We envisage that these results open up an\nexciting range of possibilities to provide microscopic insights between the\nsingle-particle behavior of soft objects at fluid interfaces and macroscopic\nmaterial properties of relevance for applications and fundamental studies\nalike."
    },
    {
        "anchor": "Theta-polymers in crowded media under the stretching force: We study the peculiarities of stretching of globular polymer macromolecules\nin a disordered (crowded) environment, using the model of self-attracting\nself-avoiding walks on site-diluted percolative lattices in space dimensions\nd=3. Applying the pruned-enriched Rosenbluth chain-growth method (PERM), we\nconstruct the phase diagram of collapsed-extended state coexistence when\nvarying temperature and stretching force. The change in shape characteristics\nof globular polymers under stretching is analyzed as well.",
        "positive": "Dissipation and recovery in collagen fibrils under cyclic loading: a\n  molecular dynamics study: The hysteretic behavior exhibited by collagen fibrils, when subjected to\ncyclic loading, is known to result in both dissipation as well as accumulation\nof residual strain. On subsequent relaxation, partial recovery has also been\nreported. Cross-links have been considered to play a key role in overall\nmechanical properties. Here, we modify an existing coarse grained molecular\ndynamics model for collagen fibril with initially cross-linked collagen\nmolecules, which is known to reproduce the response to uniaxial strain, by\nincorporating reformation of cross-links to allow for possible recovery of the\nfibril. Using molecular dynamics simulations, we show that our model\nsuccessfully replicates the key features observed in experimental data,\nincluding the movement of hysteresis loops, the time evolution of residual\nstrains and energy dissipation, as well as the recovery observed during\nrelaxation. We also show that the characteristic cycle number, describing the\napproach towards steady state, has a value similar to that in experiments. We\nalso emphasize the vital role of the degree of cross-linking on the key\nfeatures of the macroscopic response to cyclic loading."
    },
    {
        "anchor": "Quasicrystal formation in binary soft matter mixtures: Using a strategy that may be applied in theory or in experiments, we identify\nthe regime in which a model binary soft matter mixture forms quasicrystals. The\nsystem is described using classical density functional theory combined with\nintegral equation theory. Quasicrystal formation requires particle ordering\nwith two characteristic lengthscales in certain particular ratios. How the\nlengthscales are related to the form of the pair interactions is reasonably\nwell understood for one component systems, but less is known for mixtures. In\nour model mixture of big and small colloids confined to an interface, the two\nlengthscales stem from the range of the interactions between pairs of big\nparticles and from the cross big-small interactions, respectively. The\nsmall-small lengthscale is not significant. Our strategy for finding\nquasicrystals involves tuning locations of maxima in the dispersion relation,\nor equivalently in the liquid state partial static structure factors.",
        "positive": "Detailed Balance Condition and Effective Free Energy in the Primitive\n  Chain Network Model: We consider statistical mechanical properties of the primitive chain network\n(PCN) model for entangled polymers from its dynamic equations. We show that the\ndynamic equation for the segment number of the PCN model does not reduce to the\nstandard Langevin equation which satisfies the detailed balance condition. We\npropose heuristic modifications for the PCN dynamic equation for the segment\nnumber, to make it reduce to the standard Langevin equation. We analyse some\nequilibrium statistical properties of the modified PCN model, by using the\neffective free energy obtained from the modified PCN dynamic equations. The PCN\neffective free energy can be interpreted as the sum of the ideal Gaussian chain\nfree energy and the repulsive interaction energy between slip-links. By using\nthe single chain approximation, we calculate several distribution functions of\nthe PCN model. The obtained distribution functions are qualitatively different\nfrom ones for the simple slip-link model without any direct interactions\nbetween slip-links."
    },
    {
        "anchor": "Active Microrheology, Hall Effect, and Jamming in Chiral Fluids: We examine the motion of a probe particle driven through a chiral fluid\ncomposed of circularly swimming disks. We find that the probe particle travels\nin both the longitudinal direction, parallel to the driving force, and in the\ntransverse direction, perpendicular to the driving force, giving rise to a Hall\nangle. Under constant driving force, we show that the probe particle velocity\nin both the longitudinal and transverse directions exhibits nonmonotonic\nbehavior as a function of the activity of the circle swimmers. The Hall angle\nis maximized when a resonance occurs between the frequency of the chiral disks\nand the motion of the probe particle. As the density of the chiral fluid\nincreases, the Hall angle gradually decreases before reaching zero when the\nsystem enters a jammed state. We show that the onset of jamming depends on the\nchiral particle swimming frequency, with a fluid state appearing at low\nfrequencies and a jammed solid occurring at high frequencies.",
        "positive": "Q-tensor model for electrokinetics in nematic liquid crystals: We use a variational principle to derive a mathematical model for a nematic\nelectrolyte in which the liquid crystalline component is described in terms of\na second-rank order tensor. The model extends the previously developed\ndirector-based theory and accounts for presence of disclinations and possible\nbiaxiality. We verify the model by considering a simple but illustrative\nexample of liquid crystal-enabled electro-osmotic flow (LCEO) around a\nstationary dielectric spherical particle placed at the center of a large\ncylindrical container filled with a nematic electrolyte. Assuming homeotropic\nanchoring of the nematic on the surface of the particle and uniform\ndistribution of the director on the surface of the container, we consider two\nconfigurations with a disclination equatorial ring and with a hyperbolic\nhedgehog, respectively. The computed electro-osmotic flows show a strong\ndependence on the director configurations and on the anisotropies of dielectric\npermittivity and electric conductivity of the nematic characteristic of liquid\ncrystal-enabled electrokinetics. Further, the simulations demonstrate space\ncharge separation around the dielectric sphere, even in the case of isotropic\npermittivity and conductivity. This is in agreement with the induced-charge\nelectro-osmotic effect described for isotropic electrolytes surrounding\ndielectric spheres."
    },
    {
        "anchor": "Coarsening and accelerated equilibration in mass-conserving\n  heterogeneous nucleation: We propose a model of mass-conserving heterogeneous nucleation to describe\nthe dynamics of ligand-receptor binding in closed cellular compartments. When\nthe ligand dissociation rate is small, competition among receptors for free\nligands gives rise to two very different long-time ligand-receptor cluster size\ndistributions. Cluster sizes first plateau to a long-lived, initial-condition\ndependent, \"metastable\" distribution, and coarsen only much later to a\nqualitatively different equilibrium one. Surprisingly, we also find parameters\nfor which a very special subset of clusters have equal metastable and\nequilibrium sizes, appearing to equilibrate much faster than the rest. Our\nresults provide a quantitative framework for ligand binding kinetics and\nsuggest a mechanism by which different clusters can approach their equilibrium\nsizes in unexpected ways.",
        "positive": "Topological Patterns in Two-dimensional Gel Electrophoresis of DNA Knots: Gel electrophoresis is a powerful experimental method to probe the topology\nof DNA and other biopolymers. While there is a large body of experimental work\nwhich allows us to accurately separate different topoisomers of a molecule, a\nfull theoretical understanding of these experiments has not yet been achieved.\nHere we show that the mobility of DNA knots depends crucially and subtly on the\nphysical properties of the gel, and in particular on the presence of dangling\nends. The topological interactions between these and DNA molecules can be\ndescribed in terms of an \"entanglement number\", and yield a non-monotonic\nmobility at moderate fields. Consequently, in two-dimensional electrophoresis,\ngel bands display a characteristic arc pattern; this turns into a straight line\nwhen the density of dangling ends vanishes. We also provide a novel framework\nto accurately predict the shape of such arcs as a function of molecule length\nand topological complexity, which may be used to inform future experiments."
    },
    {
        "anchor": "Integral method for flows down an incline: viscous, turbulent and\n  granular cases: The integral method can be used to model accurately flows down an inclined\nplane. Such a method consists in projecting the full 3D equations on a lower\ndimensional representation. The vertical velocity profiles have their\nfunctional form fixed, based from the exact solution of homogeneous steady\nflows. This projection is achieved by integration of the momentum equation over\nthe flow depth -- Saint-Venant approach. Here we generalize the viscous case to\ntwo non-newtonian constitutive relations: a Prandtl-like turbulent closure and\na local granular rheology. We discuss one application in each case: the\nformation of anti-dunes in viscous streams, the transverse velocity profile in\nturbulent channels and the Kapitza instability in dense granular flows. They\ndemonstrate the usefulness of this approach to get a model qualitatively\ncorrect, quantitatively reasonable and in which the dynamical mechanisms at\nwork can be easily identified.",
        "positive": "Imaging of director fields in liquid crystals using stimulated Raman\n  scattering microscopy: We demonstrate an approach for background-free three-dimensional imaging of\ndirector fields in liquid crystals using stimulated Raman scattering\nmicroscopy. This imaging technique is implemented using a single femtosecond\npulsed laser and a photonic crystal fiber, providing Stokes and pump\nfrequencies needed to access Raman shifts of different chemical bonds of\nmolecules and allowing for chemically selective and broadband imaging of both\npristine liquid crystals and composite materials. Using examples of model\nthree-dimensional structures of director fields, we show that the described\ntechnique is a powerful tool for mapping of long-range molecular orientation\npatterns in soft matter via polarized chemical-selective imaging."
    },
    {
        "anchor": "Rheology of dilute cohesive granular gases: Rheology of a dilute cohesive granular gas is theoretically and numerically\nstudied. The flow curve between the shear viscosity and the shear rate is\nderived from the inelastic Boltzmann equation for particles having square-well\npotentials in a simple shear flow. It is found that (i) the stable uniformly\nsheared state only exists above a critical shear rate and (ii) the viscosity in\nthe uniformly sheared flow is almost identical to that for uniformly sheared\nflow of hard core granular particles. Below the critical shear rate, clusters\ngrow with time, in which the viscosity can be approximated by that for the\nhard-core fluids if we replace the diameter of the particle by the mean\ndiameter of clusters.",
        "positive": "Geometric frustration and pairing order transition in confined bacterial\n  vortices: Dense systems of active matter exhibit a highly dynamic collective motion\ncharacterized by intermingled vortices, referred to as active turbulence. The\ninteraction between these vortices is a key to controlling turbulent dynamics,\nand one promising approach to revealing the rules governing their interaction\nis through geometric confinement. In this study, we investigate the vortex\npairing patterns in confined bacterial suspensions as a model frustrated system\nwhere a perfect antiferromagnetic state is not allowed. We find that three-body\nvortex interactions show anomalous pairing order transition from co-rotational\nvortex pairing to the counter-rotating pattern with frustration. Although the\nactive matter system is non-equilibrium, our theory based on bending energy\naccounts for the significant features including pattern transition and the\nshift of the transition point in frustrated systems. Moreover, the interplay of\nchirality in collective motion and frustration in vortex pairing creates\ncollective rotational flow in broad geometric conditions of confined space. Our\nresults illustrate that the use of frustrated vortex patterning promotes a\ngeometric approach to arranging active turbulence in microfluidic systems."
    },
    {
        "anchor": "Orientational ordering and layering of hard plates in narrow slit-like\n  pores: We examine the ordering behavior of hard plate-like particle in a very narrow\nslit-like pore using the Parsons-Lee density functional theory and the\nrestricted orientation approximation. We observe that the plates are\norientationally ordered and align perpendicularly (face-on) to the walls at low\ndensities, a first order layering transition occurs between uniaxial nematic\nstructures having n and n+1 layers at intermediate densities and even a phase\ntransition between a monolayer with parallel (edge-on) orientational order and\nn layers with perpendicular one can be detected at high densities. In addition\nto this, the edge-on monolayer is usually biaxial nematic and a\nuniaxial-biaxial nematic phase transition can be also seen at very high\ndensities.",
        "positive": "Lattice gas study of thin film growth scenarios and transitions between\n  them: Role of substrate: Thin film growth is investigated in two types of lattice gas models where\nsubstrate and film particles are different, expressed by unequal interaction\nenergy parameters. The first is of solid-on-solid type, whereas the second type\nincorporates desorption, diffusion in the gas phase above the film and\nre-adsorption at the film (appropriate for growth in colloidal systems). The\ndifference between particle-substrate and particle-particle interactions plays\na central role for the evolution of the film morphology at intermediate times.\nThe models exhibit a dynamic layering transition which occurs at generally\nlower substrate attraction strengths than the equilibrium layering transition.\nA second, flattening transition is found where initial island growth transforms\nto layer-by-layer growth at intermediate deposition times. Combined with the\nknown roughening behavior in such models for very large deposition times, we\npresent four global growth scenarios, charting out the possible types of\nroughness evolution."
    },
    {
        "anchor": "Percolation and jamming transitions in particulate systems with and\n  without cohesion: We consider percolation and jamming transitions for particulate systems\nexposed to compression. For the systems built of particles interacting by\npurely repulsive forces in addition to friction and viscous damping, it is\nfound that these transitions are influenced by a number of effects, and in\nparticular by the compression rate. In a quasi-static limit, we find that for\nthe considered type of interaction between the particles, percolation and\njamming transitions coincide. For cohesive systems, however, or for any system\nexposed to even slow dynamics, the differences between the considered\ntransitions are found and quantified.",
        "positive": "What a twist cell experiment tells about a quartic twist theory for\n  chromonics: The elastic theory of chromonic liquid crystals is not completely\nestablished. We know, for example, that for anomalously low twist constants\n(needed for chromonics) the classical Oseen-Frank theory may entail paradoxical\nconsequences when applied to describe the equilibrium shapes of droplets\nsurrounded by an isotropic phase: contrary to experimental evidence, they are\npredicted to dissolve in a plethora of unstable smaller droplets. We proposed a\nquartic twist theory that prevents such an instability from happening. Here, we\napply this theory to the data of two experiments devised to measure the planar\nanchoring strength at the plates bounding a twist cell filled with a chromonic\nliquid crystal; these data had before been interpreted within the Oseen-Frank\ntheory. We show that the quartic twist theory affords a better agreement with\nthe experimental data, while delivering in one case a larger value for the\nanchoring strength."
    },
    {
        "anchor": "Cholesterics of colloidal helices: Predicting the macroscopic pitch from\n  the particle shape and thermodynamic state: Building a general theoretical framework to describe the microscopic origin\nof macroscopic chirality in (colloidal) liquid crystals is a long-standing\nchallenge. Here, we combine classical density functional theory with Monte\nCarlo calculations of virial-type coefficients, to obtain the equilibrium\ncholesteric pitch as a function of thermodynamic state and microscopic details.\nApplying the theory to hard helices, we observe both right- and left-handed\ncholesteric phases that depend on a subtle combination of particle geometry and\nsystem density. In particular, we find that entropy alone can even lead to a\n(double) inversion in the cholesteric sense of twist upon changing the packing\nfraction. We show how the competition between single-particle properties\n(shape) and thermodynamics (local alignment) dictates the macroscopic chiral\nbehavior. Moreover, by expanding our free-energy functional we are able to\nassess, quantitatively, Straley's theory of weak chirality, used in several\nearlier studies. Furthermore, by extending our theory to different lyotropic\nand thermotropic liquid-crystal models, we analyze the effect of an additional\nsoft interaction on the chiral behavior of the helices. Finally, we provide\nsome guidelines for the description of more complex chiral phases, like\ntwist-bend nematics. Our results provide new insights on the role of entropy in\nthe microscopic origin of this state of matter.",
        "positive": "Hydrodynamic interactions of spherical particles in Poiseuille flow\n  between two parallel walls: We study hydrodynamic interactions of spherical particles in incident\nPoiseuille flow in a channel with infinite planar walls. The particles are\nsuspended in a Newtonian fluid, and creeping-flow conditions are assumed.\nNumerical results, obtained using our highly accurate Cartesian-representation\nalgorithm [Physica A xxx, {\\bf xx}, 2005], are presented for a single sphere,\ntwo spheres, and arrays of many spheres. We consider the motion of freely\nsuspended particles as well as the forces and torques acting on particles\nadsorbed at a wall. We find that the pair hydrodynamic interactions in this\nwall-bounded system have a complex dependence on the lateral interparticle\ndistance due to the combined effects of the dissipation in the gap between the\nparticle surfaces and the backflow associated with the presence of the walls.\nFor immobile particle pairs we have examined the crossover between several\nfar-field asymptotic regimes corresponding to different relations between the\nparticle separation and the distances of the particles from the walls. We have\nalso shown that the cumulative effect of the far-field flow substantially\ninfluences the force distribution in arrays of immobile spheres. Therefore, the\nfar-field contributions must be included in any reliable algorithm for\nevaluating many-particle hydrodynamic interactions in the parallel-wall\ngeometry."
    },
    {
        "anchor": "Reorganization asymmetry of electron transfer in ferroelectric media and\n  principles of artificial photosynthesis: This study considers electronic transitions within donor-acceptor complexes\ndissolved in media with macroscopic polarization. The change of the\npolarizability of the donor-acceptor complex in the course of electronic\ntransition couples to the reaction field of the polar environment and the\nelectric field created by the macroscopic polarization. An analytical theory\ndeveloped to describe this situation predicts a significant asymmetry of the\nreorganization energy between charge separation and charge recombination\ntransitions. This result is proved by Monte Carlo simulations of a model\npolarizable diatomic dissolved in a ferroelectric fluid of soft dipolar\nspheres. The ratio of the reorganization energies for the forward and backward\nreactions up to a factor of 25 is obtained in the simulations. This result, as\nwell as the effect of the macroscopic electric field, is discussed in\napplication to the design of efficient photosynthetic devices.",
        "positive": "Stochastic resonance in soft matter systems: combined effects of static\n  and dynamic disorder: We study the impact of static and dynamic disorder on the phenomenon of\nstochastic resonance (SR) in a representative soft matter system. Due to their\nextreme susceptibility to weak perturbations soft matter systems appear to be\nexcellent candidates for the observation of SR. Indeed, we derive generic SR\nequations from a polymer stabilized ferroelectric liquid crystal (LC) cell,\nwhich is a typical soft matter representative constituting one of the basic\ncomponents in several electro-optic applications. We generalize these equations\nfurther in order to study an even broader class of qualitatively different\nsystems, especially disclosing the influence of different types of static\ndisorder and interaction ranges amongst LC molecules on the SR response. We\ndetermine the required conditions for the observation of SR in the examined\nsystem, and moreover, reveal that a random field type static disorder yields\nqualitatively different responses with respect to random dilution, random bond\nand spin glass universality classes. In particular, while the latter three\ndecrease the level of dynamic disorder (Gaussian noise) warranting the optimal\nresponse, the former evokes exactly the opposite effect, hence increasing the\noptimal noise level that is needed to resonantly fine-tune the system's\nresponse in accordance with the weak deterministic electric field. These\nobservations are shown to be independent of the system size and range of\ninteractions, thus implying their general validity and potentially wide\napplicability also within other similar settings. We argue that soft matter\nsystems might be particularly adequate as a base for different SR-based\nsensitive detectors and thus potent candidates for additional theoretical as\nwell as experimental research in the presently outlined direction."
    },
    {
        "anchor": "Theory of Suspension Segregation in Partially Filled Horizontal Rotating\n  Cylinders: It is shown that a suspension of particles in a partially-filled, horizontal,\nrotating cylinder is linearly unstable towards axial segregation and an\nundulation of the free surface at large enough particle concentrations. Relying\non the shear-induced diffusion of particles, concentration-dependent viscosity,\nand the existence of a free surface, our theory provides an explanation of the\nexperiments of Tirumkudulu et al., Phys. Fluids 11, 507-509 (1999); ibid. 12,\n1615 (2000).",
        "positive": "Vortex sorter for Bose-Einstein condensates: We have designed interferometers that sort Bose-Einstein condensates into\ntheir vortex components. The Bose-Einstein condensates in the two arms of the\ninterferometer are rotated with respect to each other through fixed angles;\ndifferent vortex components then exit the interferometer in different\ndirections. The method we use to rotate the Bose-Einstein condensates involves\nasymmetric phase imprinting and is itself new. We have modelled rotation\nthrough fixed angles and sorting into vortex components with even and odd\nvalues of the topological charge of 2-dimensional Bose-Einstein condensates in\na number of states (pure or superposition vortex states for different values of\nthe scattering length). Our scheme may have applications for quantum\ninformation processing."
    },
    {
        "anchor": "Deformation and Fabric in Compacted Clay Soils: Hydro-mechanical anisotropy of clay soils in response to deformation or\ndeposition history is related to the micromechanics of plate-like clay\nparticles and their orientations. In this letter, we examine the relationship\nbetween microstructure, deformation and moisture content in kaolin clay using a\ntechnique based on neutron scattering. This technique allows for the direct\ncharacterisation of the microstructure within representative samples using\ntraditional measures such as the orientation density function and soil fabric\ntensor. From this information, evidence for a simple relationship between\ncomponents of the deviatoric strain tensor and the deviatoric fabric tensor\nemerged. This relationship provides a physical basis for future anisotropic\nconstitutive models based on the micromechanics of these materials.",
        "positive": "Microscopic Evolution of a Weakly Interacting Homogeneous Bose Gas: We provide a detailed description of the nonequilibrium time evolution of an\ninteracting homogeneous Bose-Einstein condensate. We use a nonperturbative\nin-medium quantum field theory approach as a microscopic model for the Bose\ngas. The real-time dynamics of the condensate is encoded in a set of\nself-consistent equations which corresponds to an infinite sum of ladder\nFeynman diagrams. The crucial role played by the interaction between\nfluctuations for the instability generation is thoroughly described."
    },
    {
        "anchor": "Ion specificity of confined ion-water structuring and nanoscale surface\n  forces in clays: Ion specificity and related Hofmeister effects, ubiquitous in aqueous\nsystems, can have spectacular consequences in hydrated clays, where\nion-specific nanoscale surface forces can determine large scale cohesive,\nswelling and shrinkage behaviors of soil and sediments. We have used a\nsemi-atomistic computational approach and examined sodium, calcium and aluminum\ncounterions confined with water between charged surfaces representative of clay\nmaterials, to show that ion-water structuring in nanoscale confinement is at\nthe origin of surface forces between clay particles which are intrinsically\nion-specific. When charged surfaces strongly confine ions and water, the\namplitude and oscillations of the net pressure naturally emerge from the\ninterplay of electrostatics and steric effects, which can not be captured by\nexisting theories. Increasing confinement and surface charge densities promote\nion-water structures that increasingly deviate from the ions' bulk hydration\nshells, being strongly anisotropic and persistent, and self-organizing into\noptimized, nearly solid-like assemblies where hardly any free water is left. In\nthese conditions, strongly attractive interactions can prevail between charged\nsurfaces, due to the dramatically reduced dielectric screening of water and the\nhighly organized water-ion structures. By unravelling the ion-specific nature\nof these nanoscale interactions, we provide evidence that ion-specific\nsolvation structures determined by confinement are at the origin of ion\nspecificity in clays and potentially a broader range of confined aqueous\nsystems.",
        "positive": "Microscopic Reversibility and Emergent Elasticity in Ultrastable\n  Granular Systems: In a recent paper [Phys. Rev. X 12, 031021], we reported experimental\nobservations of ``ultrastable'' states in a shear-jammed granular system\nsubjected to small-amplitude cyclic shear. In such states, all the particle\npositions and contact forces are reproduced after each shear cycle so that a\nstrobed image of the stresses and particle positions appears static. In the\npresent work, we report further analyses of data from those experiments to\ncharacterize both global and local responses of ultrastable states within a\nshear cycle, not just the strobed dynamics. We find that ultrastable states\nfollow a power-law relation between shear modulus and pressure with an exponent\n$\\beta\\approx 0.5$, reminiscent of critical scaling laws near jamming. We also\nexamine the evolution of contact forces measured using photoelasticimetry. We\nfind that there are two types of contacts: non-persistent contacts that\nreversibly open and close; and persistent contacts that never open \\yiqiu{and\ndisplay no measurable sliding}. We show that the non-persistent contacts make a\nnon-negligible contribution to the emergent shear modulus. We also analyze the\nspatial correlations of the stress tensor and compare them to the predictions\nof a recent theory of the emergent elasticity of granular solids, the Vector\nCharge Theory of Granular mechanics and dynamics (VCTG) [Phys. Rev. Lett. 125,\n118002, arXiv:2204.11811]. We show that our experimental results can be fit\nwell by VCTG, assuming uniaxial symmetry of the contact networks. The fits\nreveal that the response of the ultrastable states to additional applied stress\nis substantially more isotropic than that of the original shear-jammed states.\nOur results provide important insight into the mechanical properties of\nfrictional granular solids created by shear."
    },
    {
        "anchor": "Influence of drying conditions on the stress and weight development of\n  capillary suspensions: Cracking of suspensions during drying is a common problem. While additives,\ne.g. binders and surfactants, can mitigate this problem, some applications,\nsuch as printing conductive pastes or sintering green bodies, do not lend\nthemselves to the use of additives. Capillary suspensions provide an\nalternative formulation without additives. In this work, we use simultaneous\nstress and weight measurements to investigate the influence of formulation and\ndrying conditions. Capillary suspensions dry more homogeneously and with lower\npeak stresses, leading to an increased robustness against cracking compared. An\nincrease in dry film porosity is not the key driver for the stress reduction.\nInstead, the capillary bridges, which create strong particle networks, resist\nthe stress. Increasing the relative humidity enhances this effect, even for\npure suspensions. While lower boiling point secondary liquids, e.g. water,\npersist for very long times during drying, higher boiling point liquids offer\nfurther potential to tune the the drying process.",
        "positive": "Shear jamming and shear melting in mechanically trained frictionless\n  particles: We investigate criticality near the jamming transition in both quiescent\nsystems and those under shear by considering the effect of mechanical training\non the jamming transition and nonlinear rheology. We simulate frictionless soft\nparticles undergoing athermal quasi-static shear using initial configurations\ntrained with athermal quasi-static cyclic volume deformations. The jamming\ntransition density of the initial configuration $\\varphi_{\\rm J0}$ is\nsystematically altered by tuning the ``depth'' of mechanical training. We exert\na steady shear on these configurations and observe either shear jamming (gain\nof stiffness due to shear) or shear melting (loss of stiffness due to shear),\ndepending on the depth of training and proximity to the jamming transition\ndensity. We also observe that the characteristic strains, at which shear\njamming or melting occur, diverge at a unique density $\\varphi_{\\rm JS}$. This\nis due to the shift of the jamming transition density from $\\varphi_{\\rm J0}$\nto $\\varphi_{\\rm JS}$ under shear, associated with loss of memory of the\ninitial configuration. Finally, we thoroughly investigate nonlinear rheology\nnear the jamming transition density, and contrary to previous works, we find a\nnonlinear ``softening'' takes place below as well as above the jamming\ntransition density."
    },
    {
        "anchor": "Rotating Micro-Spheres for Adsorption Monitoring at a Fluid Interface: Hypothesis: A broad range of phenomena, such as emulsification and emulsion\nstability, foam formation or liquid evaporation, are closely related to the\ndynamics of adsorbing colloidal particles. Elucidation of the mechanisms\nimplied is key to a correct design of many different types of materials.\n  Experiments: Microspheres forced to rotate near a fluid interface exhibit a\nroto-translational hydrodynamic mechanism that is hindered by capillary torques\nas soon as the particles protrude the interface. Under these conditions, the\ntime evolution in the ratio of moving spheres provides a direct description of\nthe adsorption kinetics, while microscopy monitoring of particle\nacceleration\\deceleration informs about the adsorption\\desorption dynamics. In\nthis work, the proposed strategy is applied at an air/water interface loaded\nwith spherical magnetic particles negatively charged, forced to rotate by the\naction of a rotating magnetic field.\n  Findings: The proposed method enables the adsorption/desorption dynamics to\nbe followed during the earliest phase of the process, when desorption of a\nsmall fraction of particles is detected, as well as to estimate approximated\nvalues of the adsorption/desorption constants. The results obtained show that\nthe addition of a monovalent salt or a cationic (anionic) surfactant promotes\n(inhibits) both adsorption and formation of permanent bonds between particles.",
        "positive": "The morphology and dynamics of polymerization-induced phase separation: The morphology and dynamics of polymerization-induced phase separation in the\ninitially homogeneous solution of a non-reactive component in reactive monomers\nare investigated by incorporating the reaction kinetics into the time-dependent\nGinzburg Landau equation. Analytical results show that there is a reduction of\nthe initial length scale in the early stage of phase separation. The reason is\nthe increase of the molecule weight of emerging polymer, independent of the\nfact whether the system goes through the metastable region or not. The\nnumerical results are in good agreement with theoretical prediction quite well."
    },
    {
        "anchor": "Desorption of hydrocarbon chains by association with ionic and nonionic\n  surfactants under flow as a mechanism for enhanced oil recovery: The need to extract oil from wells where it is embedded on the surfaces of\nrocks has led to the development of new and improved enhanced oil recovery\ntechniques. One of those is the injection of surfactants with water vapor,\nwhich promotes desorption of oil that can then be extracted using pumps, as the\nsurfactants encapsulate the oil in foams. However, the mechanisms that lead to\nthe optimal desorption of oil and the best type of surfactants to carry out\ndesorption are not well known yet, which warrants the need to carry out basic\nresearch on this topic. In this work, we report non equilibrium dissipative\nparticle dynamics simulations of model surfactants and oil molecules adsorbed\non surfaces, with the purpose of studying the efficiency of the surfactants to\ndesorb hydrocarbon chains, that are found adsorbed over flat surfaces. The\nmodel surfactants studied correspond to nonionic and cationic surfactants, and\nthe hydrocarbon desorption is studied as a function of surfactant concentration\nunder increasing Poiseuille flow. We obtain various hydrocarbon desorption\nisotherms for every model of surfactant proposed, under flow. Nonionic\nsurfactants are found to be the most effective to desorb oil and the mechanisms\nthat lead to this phenomenon are presented and discussed.",
        "positive": "Microscopic Details of a Fluid/Thin Film Triple Line: In recent years, there has been a considerable interest in the mechanics of\nsoft objects meeting fluid interfaces (elasto-capillary interactions). In this\nwork we experimentally examine the case of a fluid resting on a thin film of\nrigid material which, in turn, is resting on a fluid substrate. To simplify\ncomplexity, we adapt the experiment to a one-dimensional geometry and examine\nthe behaviour of polystyrene and polycarbonate films directly with confocal\nmicroscopy. We find that the fluid meets the film in a manner consistent with\nthe Young-Dupr\\'e equation when the film is thick, but transitions to what\nappears similar to a Neumann like balance when the thickness is decreased.\nHowever, on closer investigation we find that the true contact angle is always\ngiven by the Young construction. The apparent paradox is a result of\nmacroscopically measured angles not being directly related to true microscopic\ncontact angles when curvature is present. We model the effect with the\nEuler-Bernoulli beam on a Winkler foundation as well as with an equivalent\nenergy based capillary model. Notably, the models highlight several important\nlengthscales and the complex interplay of tension, gravity and bending in the\nproblem."
    },
    {
        "anchor": "Localization transition of random copolymers at interfaces: We consider adsorption of random copolymer chains onto an interface within\nthe model of Garel et al. Europhysics Letters 8, 9 (1989). By using the replica\nmethod the adsorption of the copolymer at the interface is mapped onto the\nproblem of finding the ground state of a quantum mechanical Hamiltonian. To\nstudy this ground state we introduce a novel variational principle for the\nGreen's function, which generalizes the well-known Rayleigh-Ritz method of\nQuantum Mechanics to nonstationary states. Minimization with an appropriate\ntrial Green's function enables us to find the phase diagram for the\nlocalization-delocalization transition for an ideal random copolymer at the\ninterface.",
        "positive": "Towards a variational principle for motivated vehicle motion: We deal with the problem of deriving the microscopic equations governing the\nindividual car motion based on the assumptions about the strategy of driver\nbehavior. We suppose the driver behavior to be a result of a certain compromise\nbetween the will to move at a speed that is comfortable for him under the\nsurrounding external conditions, comprising the physical state of the road, the\nweather conditions, etc., and the necessity to keep a safe headway distance\nbetween the cars in front of him. Such a strategy implies that a driver can\ncompare the possible ways of his further motion and so choose the best one. To\ndescribe the driver preferences we introduce the priority functional whose\nextremals specify the driver choice. For simplicity we consider a single-lane\nroad. In this case solving the corresponding equations for the extremals we\nfind the relationship between the current acceleration, velocity and position\nof the car. As a special case we get a certain generalization of the optimal\nvelocity model similar to the \"intelligent driver model\" proposed by Treiber\nand Helbing."
    },
    {
        "anchor": "Driving an electrolyte through a corrugated nanopore: We characterize the dynamics of a $z-z$ electrolyte embedded in a\nvarying-section channel. In the linear response regime, by means of suitable\napproximations, we derive the Onsager matrix associated to externally enforced\ngradients in electrostatic potential, chemical potential, and pressure, for\nboth dielectric and conducting channel walls. We show here that the linear\ntransport coefficients are particularly sensitive to the geometry and the\nconductive properties of the channel walls when the Debye length is comparable\nto the channel width. In this regime, we found that one pair of off-diagonal\nOnsager matrix elements increases with the corrugation of the channel\ntransport, in contrast to all other elements which are either unaffected by or\ndecrease with increasing corrugation. Our results have a possible impact on the\ndesign of blue-energy devices as well as on the understanding of biological ion\nchannels through membranes",
        "positive": "Influence of polymer-pore interactions on translocation: We investigate the influence of polymer-pore interactions on the\ntranslocation dynamics using Langevin dynamics simulations. An attractive\ninteraction can greatly improve translocation probability. At the same time, it\nalso increases translocation time slowly for weak attraction while exponential\ndependence is observed for strong attraction. For fixed driving force and chain\nlength the histogram of translocation time has a transition from Gaussian\ndistribution to long-tailed distribution with increasing attraction. Under a\nweak driving force and a strong attractive force, both the translocation time\nand the residence time in the pore show a non-monotonic behavior as a function\nof the chain length. Our simulations results are in good agreement with recent\nexperimental data."
    },
    {
        "anchor": "Ultrafast reversible self-assembly of living tangled matter: Tangled active filaments are ubiquitous in nature, from chromosomal DNA and\ncilia carpets to root networks and worm blobs. How activity and elasticity\nfacilitate collective topological transformations in living tangled matter is\nnot well understood. Here, we report an experimental and theoretical study of\nCalifornia blackworms (Lumbriculus variegatus), which slowly form tangles over\nminutes but can untangle in milliseconds. Combining ultrasound imaging,\ntheoretical analysis and simulations, we develop and validate a mechanistic\nmodel that explains how the kinematics of individual active filaments\ndetermines their emergent collective topological dynamics. The model reveals\nthat resonantly alternating helical waves enable both tangle formation and\nultrafast untangling. By identifying generic dynamical principles of\ntopological self-transformations, our results can provide guidance for\ndesigning new classes of topologically tunable active materials.",
        "positive": "Structure and Dynamics of Hybrid Colloid-Polyelectrolyte Coacervates:\n  Insights from Molecular Simulations: Electrostatic interactions in polymeric systems are responsible for a wide\nrange of liquid-liquid phase transitions that are of importance for biology and\nmaterials science. Such transitions are referred to as complex coacervation,\nand recent studies have sought to understand the underlying physics and\nchemistry. Most theoretical and simulation efforts to date have focused on\noppositely charged linear polyelectrolytes, which adopt nearly ideal-coil\nconformations in the condensed phase. However, when one of the coacervate\ncomponents is a globular protein, a better model of complexation should replace\none of the species with a spherical charged particle or colloid. In this work,\nwe perform coarse-grained simulations of colloid-polyelectrolyte coacervation\nusing a spherical model for the colloid. Simulation results indicate that the\nelectroneutral cell of the resulting (hybrid) coacervates consists of a\npolyelectrolyte layer adsorbed on the colloid. Power laws for the structure and\nthe density of the condensed phase, which are extracted from simulations, are\nfound to be consistent with the adsorption-based scaling theory of\ncoacervation. The coacervates remain amorphous (disordered) at a moderate\ncolloid charge, $Q$, while an intra-coacervate colloidal crystal is formed\nabove a certain threshold, at $Q > Q^{*}$. In the disordered coacervate, if $Q$\nis sufficiently low, colloids diffuse as neutral non-sticky nanoparticles in\nthe semidilute polymer solution. For higher $Q$, adsorption is strong and\ncolloids become effectively sticky. Our findings are relevant for the\ncoacervation of polyelectrolytes with proteins, spherical micelles of ionic\nsurfactants, and solid organic or inorganic nanoparticles."
    },
    {
        "anchor": "Elastic and Proton Dynamics of the DNA: The subject of this report is the dynamics of elastic system in conjunction\nwith hydrogen bonds of the DNA. We draw attention to the draw-back of the\nfamiliar rod model of the DNA, and make a case of constructing models that\ncould accommodate the intrinsic structure of the DNA. In this respect studying\nthe interplay among the elastic system and the protons of the DNA, is of\ninterest, for it could accommodate the inter-strand as well as the tunneling\nmodes of protons. Following this direction, we come to the conclusion that the\nelastic-proton dynamics may have a bearing on biophysics of the DNA. The\nphenomenon of point mutations is discussed within this framework.",
        "positive": "Colloidal systems with competing interactions: from an arrested\n  repulsive cluster phase to a gel: We report an extensive numerical study of a charged colloidal system with\ncompeting short-range depletion attraction and long-range electrostatic\nrepulsion. By analizing the cluster properties, we identify two distinct\nregions in the phase diagram: a state composed of stable finite-size clusters,\nwhose relative interactions are dominated by long-range repulsion, and a\npercolating network. Both states are found to dynamically arrest at low\ntemperatures, providing evidence of the existence of two distinct non-ergodic\nstates in these systems: a Wigner glass of clusters and a gel."
    },
    {
        "anchor": "Simulation-based equation of state of the hard disk fluid and prediction\n  of higher-order virial coefficients: We present new molecular dynamics results for the pressure of the pure hard\ndisk fluid up to the hexatic transition (about reduced density 0.9). The data\ncombined with the known virial coefficients (up to $B_{10}$) are used to build\nan equation of state, to estimate higher-order virial coefficients, and also to\nobtain a better value of $B_{10}$. Finite size effects are discussed in detail.\nThe ``van der Waals-like'' loop reported in literature in the vicinity of the\nfluid/hexatic transition is explained by suppressed density fluctuations in the\ncanonical ensemble. The inflection point on the pressure-density dependence is\npredicted by the equation of state even if the hexatic phase simulation data\nare not considered.",
        "positive": "Multiscale Dynamics of Lipid Vesicles in Polymeric Microenvironment: Understanding dynamic and complex interaction of biological membranes with\nextracellular matrices plays a crucial role in controlling a variety of cell\nbehavior and functions, from cell adhesion and growth to signaling and\ndifferentiation. Tremendous interest in tissue engineering has made it possible\nto design polymeric scaffolds mimicking the topology and mechanical properties\nof the native extracellular microenvironment; however, a fundamental question\nremains unanswered: that is, how the viscoelastic extracellular environment\nmodifies the hierarchical dynamics of lipid membranes. In this work, we used\naqueous solutions of poly(ethylene glycol) (PEG) with different molecular\nweights to mimic the viscous medium of cells and nearly monodisperse\nunilamellar DMPC DMPG liposomes as a membrane model. Using small angle Xray\nscattering (SAXS), dynamic light scattering, temperature modulated differential\nscanning calorimetry, bulk rheology, and fluorescence lifetime spectroscopy, we\ninvestigated the structural phase map and multiscale dynamics of the liposome\npolymer mixtures. The results suggest an unprecedented dynamic coupling between\npolymer chains and phospholipid bilayers at different length and time scales.\nThe microviscosity of the lipid bilayers is directly influenced by the\nrelaxation of the whole chain, resulting in accelerated dynamics of lipids\nwithin the bilayers in the case of short chains compared to the polymer free\nliposome case. At the macroscopic level, the gel to fluid transition of the\nbilayers results in a remarkable thermal stiffening behavior of polymer\nliposome solutions that can be modified by the concentration of the liposomes\nand the polymer chain length."
    },
    {
        "anchor": "Microfluidic osmotic compression of a charge-stabilized colloidal\n  dispersion: Equation of state and collective diffusion coefficient: We show, using a model coupling mass transport and liquid theory calculations\nfor a charge-stabilized colloidal dispersion, that diffusion significantly\nlimits measurement times of its Equation Of State (EOS), osmotic pressure vs\ncomposition, using the osmotic compression technique. Following this result, we\npresent a microfluidic chip allowing one to measure the entire EOS of a charged\ndispersion at the nanoliter scale in a few hours. We also show that\ntime-resolved analyses of relaxation to equilibrium in this microfluidic\nexperiment lead to direct estimates of the collective diffusion coefficient of\nthe dispersion in Donnan equilibrium with a salt reservoir.",
        "positive": "Lateral depletion effect on two-dimensional ordering of\n  bacteriorhodopsins in a lipid bilayer: A theoretical study based on a binary\n  hard-disk model: The two-dimensional ordering of bacteriorhodopsins in a lipid bilayer was\nstudied using a binary hard-disk model. The phase diagrams were calculated,\ntaking into account the lateral depletion effects. The critical concentrations\nof the protein ordering for the monomers and the trimers were obtained from the\nphase diagrams. The critical concentration ratio agreed well with the\nexperiment when the repulsive core interaction between the depletants, namely\nthe lipids, was taken into account. The results suggest that the depletion\neffect plays an important role in the association behaviors of transmembrane\nproteins."
    },
    {
        "anchor": "Non-equilibrium dynamics of initially spherical vesicles in general flow: Many vesicles have a spherical resting shape and exposure to fluid flows\ninduces an exchange between sub-optical area and visible (systematic)\ndeformation, while the total area is conserved. The dynamics which controls the\nexchange between sub-optical and visible area depends on membrane properties\nsuch as bending rigidity and initial tension. Conversely, observation of these\ndynamics can be used to determine the membrane properties. The goal of this\nwork is to create a general numerical model which accounts for the exchange\nbetween sub-optical and visible area. Unlike prior modeling efforts, the model\ndoes not pre-assume a shape type, such as nearly-spherical, or applied flow\nfield, allowing the model to capture a wider variety of flow conditions. Based\non implicit interface tracking and using a volume-preserving multiphase\nNavier-Stokes solver, the model is compared to several experimental results,\nshowing excellent agreement. It is used to explore regimes not possible with\npreviously published models, such as the variable viscosity case, and how these\nsystem properties influence experimentally measurable parameters such as\ndeformation parameter. By creating a more generalized framework for the\nmodeling of vesicles with sub-optical area, it will now be possible to make\npredictions on vesicle material properties from a wider variety of experimental\nresults.",
        "positive": "Density distribution for the molecules of a liquid in a semi-infinite\n  space: The Sutherland approximation to the van der Waals forces is applied to the\nderivation of a self-consistent Vlasov-type field in a liquid filling a half\nspace, bordering vacuum. The ensuing Vlasov equation is then derived, and\nsolved to predict the behavior of the density at and in the vicinity of the\nliquid-vacuum interface. A numerical solution to the Vlasov equation is also\nproduced and the density profile shown and discussed."
    },
    {
        "anchor": "Electrolytes between dielectric charged surfaces: Simulations and theory: We present a simulation method to study electrolyte solutions in a dielectric\nslab geometry using a modified 3D Ewald summation. The method is fast and easy\nto implement, allowing us to rapidly resum an infinite series of image charges.\nIn the weak coupling limit, we also develop a mean-field theory which allows us\nto predict the ionic distribution between the dielectric charged plates. The\nagreement between both approaches, theoretical and simulational, is very good,\nvalidating both methods. Examples of ionic density profiles in the strong\nelectrostatic coupling limit are also presented. Finally, we explore the\nconfinement of charge asymmetric electrolytes between neutral surfaces.",
        "positive": "Entanglement Density Tunes Microscale Nonlinear Response of Entangled\n  Actin: We optically drive a microsphere at constant speed through entangled actin\nnetworks of 0.2 - 1.4 mg/ml at rates faster than the critical rate controlling\nthe onset of a nonlinear response. By measuring the resistive force exerted on\nthe microsphere during and following strain we reveal a critical concentration\n$c^{*}\\simeq0.4$ mg/ml for nonlinear features to emerge. For $c>c^{*}$,\nentangled actin stiffens at short times with the degree of stiffening $S$ and\ncorresponding timescale $t_{stiff}$ scaling with the entanglement tube density,\ni.e. $S\\sim t_{stiff}\\sim d_t^{-1}\\sim c^{3/5}$. The network subsequently\nyields to a viscous regime with the yield distance $d_y$ scaling linearly with\nyield force $f_y$ and inversely with the entanglement length ($f_y\\sim d_y\\sim\nl_{e}^{-1} \\sim c^{2/5}$). Stiffening and yielding dynamics are consistent with\nrecent theoretical predictions for nonlinear cohesive breakdown of\nentanglements. We further show that above $c^{*}$ force relaxation proceeds via\nslow filament disengagement from dilated tubes coupled with $\\sim$10x faster\nlateral hopping, with the corresponding concentration dependences in agreement\nwith recent theoretical predictions for entangled rigid rods."
    },
    {
        "anchor": "Kink propagation in the Artificial Axon: The Artificial Axon is a unique synthetic system, based on biomolecular\ncomponents, which supports action potentials. Here we consider, theoretically,\nthe corresponding space extended system, and discuss the occurrence of solitary\nwaves, or kinks. In contrast to action potentials, stationary kinks are\npossible. We point out an analogy with the interface separating two condensed\nmatter phases, though our kinks are always non-equilibrium, dissipative\nstructures, even when stationary.",
        "positive": "Bending of Biomimetic Scale Covered Beams Under Discrete Non-periodic\n  Engagement: Covering elastic substrates with stiff biomimetic scales significantly alters\nthe bending behavior via scales engagement. This engagement is the dominant\nsource of nonlinearity in small deflection regime. As deformation proceeds, an\ninitially linear bending response gives way to progressive stiffening and\nthereafter a geometrically dictated 'locked' configuration. However,\ninvestigation of this system has been carried out until date using assumption\nof periodic engagement even after scales contact. This is true only under the\nmost ideal loading conditions or if the scales are extremely dense akin to a\ncontinuum assumption on the scales. However, this is not true for a practical\nsystem where scales are more discrete and where loading can alter periodicity\nof engagement. We address this nonlinear problem for the first time in small\ndeflection and rotation regime. Our combined modeling and numerical analysis\nshow that relaxing periodicity better represents the geometry of discrete\nscales engagement and mechanics of the beam under general loading conditions\nand allows us to revisit the nonlinear behavior. We report significant\ndifferences from predictions of periodic models in terms of predicting the\nbehavior of scales after engagement. These include the difference in the\nangular displacement of scales, normal force magnitudes along the length,\nmoment curvature relationship as well as a distinct nature of the locking\nbehavior. Therefore, non-periodicity is an important yet unexplored feature of\nthis problem, which leads to insights, absent in previous investigations. This\nopens way for developing the structure-property-architecture framework for\ndesign and optimization of these topologically leveraged solids."
    },
    {
        "anchor": "Moderate Point: Balanced Entropy and Enthalpy Contributions in Soft\n  Matter: Various soft materials share some common features, such as significant\nentropic effect, large fluctuations, sensitivity to thermodynamic conditions,\nand mesoscopic characteristic spatial and temporal scales. However, no\nquantitative definitions have yet been provided for soft matter, and the\nintrinsic mechanisms leading to their common features are unclear. In this\nwork, from the viewpoint of statistical mechanics, we show that soft matter\nworks in the vicinity of a specific thermodynamic state named moderate point,\nat which entropy and enthalpy contributions among substates along a certain\norder parameter are well balanced or have a minimal difference. Around the\nmoderate point, the order parameter fluctuation, the associated response\nfunction, and the spatial correlation length maximize, which explains the large\nfluctuation, the sensitivity to thermodynamic conditions, and mesoscopic\nspatial and temporal scales of soft matter, respectively. Possible applications\nto switching chemical bonds or allosteric biomachines determining their best\nworking temperatures are also discussed.",
        "positive": "First-order patterning transitions on a sphere as a route to cell\n  morphology: We propose a general theory for surface patterning in many different\nbiological systems, including mite and insect cuticles, pollen grains, fungal\nspores, and insect eggs. The patterns of interest are often intricate and\ndiverse, yet an individual pattern is robustly reproducible by a single species\nand a similar set of developmental stages produces a variety of patterns. We\nargue that the pattern diversity and reproducibility may be explained by\ninterpreting the pattern development as a first-order phase transition to a\nspatially modulated phase. Brazovskii showed that for such transitions on a\nflat, infinite sheet, the patterns are uniform striped or hexagonal. Biological\nobjects, however, have finite extent and offer different topologies, such as\nthe spherical surfaces of pollen grains. We consider Brazovskii transitions on\nspheres and show that the patterns have a richer phenomenology than simple\nstripes or hexagons. We calculate the free energy difference between the\nunpatterned state and the many possible patterned phases, taking into account\nfluctuations and the system's finite size. The proliferation of variety on a\nsphere may be understood as a consequence of topology, which forces defects\ninto perfectly ordered phases. The defects are then accommodated in different\nways. We also argue that the first-order character of the transition is\nresponsible for the reproducibility and robustness of the pattern formation."
    },
    {
        "anchor": "Nematic twist--bend phase in an external field: Nematic twist--bend is the fifth nematic phase recognized in nature. This\nphase exhibits spiral orientational order, thus it is a chiral structure and it\ncan be stabilized in systems composed of achiral molecules. The microscopic\norigin of this spontaneous chiral symmetry breaking is to a large extent\nunknown but phenomenologically it appears stabilized by assuming coupling\nbetween steric polar and orientational orderings. Understanding of how external\nfields affect the stability of this phase is of great intellectual interest and\nof relevance to potential applications. Within mesoscopic Landau--de Gennes\ntheory we find that for compounds with positive anisotropy the helix unwinds to\na polar uniaxial nematic, however negative material anisotropy gives rise to a\nrich sequence of new nematic phases obtained via mechanism of flattening the\nconical spiral.",
        "positive": "The hierarchical properties of contact networks in granular packings: The topological structure resulting from the network of contacts between\ngrains (contact network) is studied for very large samples of disorderly-packed\nmonosized spheres with densities ranging from 0.58 to 0.64. The hierarchical\norganization of such a structure is studied by means of a topological map which\nstarts from a given sphere and moves outwards in concentric shells through the\ncontact network. We find that the topological density of disordered sphere\npacking is larger than the topological density of equivalent lattice sphere\npackings."
    },
    {
        "anchor": "Huge broadening of the crystal-fluid interface for sedimenting colloids: For sedimenting colloidal hard spheres, the propagation and broadening of the\ncrystal-fluid interface is studied by Brownian dynamics computer simulations of\nan initially homogeneous sample. Two different types of interface broadenings\nare observed: the first occurs during growth and is correlated with the\ninterface velocity, the second is concomitant with the splitting of the\ncrystal-fluid interface into the crystal-amorphous and amorphous-liquid\ninterfaces. The latter width is strongly peaked as a function of the\ngravitational driving strength with a huge amplitude relative to its\nequilibrium counterpart.",
        "positive": "The search for Nanobubbles by using specular and off-specular Neutron\n  Reflectometry: We apply specular and off-specular neutron reflection at the hydrophobic\nsilicon/water interface to check for evidence of nanoscopic air bubbles whose\npresence is claimed after an ad hoc procedure of solvent exchange. Nanobubbles\nand/or a depletion layer at the hydrophobic/water interface have long been\ndiscussed and generated a plethora of controversial scientific results. By\ncombining neutron reflectometry (NR), off-specular reflectometry (OSS) and\ngrazing incidence small angle neutron scattering (GISANS), we studied the\ninterface between hydrophobized silicon and heavy water before and after\nsaturation with nitrogen gas. Our specular reflectometry results can be\ninterpreted by assuming a sub-molecular sized depletion layer and the\noff-specular measurements show no change with nitrogen super saturated water.\nThis picture is consistent with the assumption that, following the solvent\nexchange, no additional nanobubbles are introduced at significant\nconcentrations (if present at all). Furthermore, we discuss the results, in\nterms of the maximum surface coverage of nanobubbles that could be present on\nthe hydrophobic surface compatibly with the sensitivity limit of these\ntechniques."
    },
    {
        "anchor": "Shear zones in granular media: 3D Contact Dynamics simulation: Shear zone formation is investigated in slow 3D shear flows. We simulate the\nlinear version of the split-bottom shear cell. It is shown that the same type\nof wide shear zones is achieved in the presence as well as in the absence of\ngravity. We investigate the relaxation of the material towards a stationary\nflow and analyze the stress and the velocity fields. We provide the functional\nform of the widening of the shear zone inside the bulk. We discuss the growth\nof the region where the material is in critical state. It is found that the\ngrowth of the critical zone is responsible for the initial transient of the\nshear zone.",
        "positive": "Flexibility-induced effects in the Brownian motion of colloidal trimers: Shape changes resulting from segmental flexibility are ubiquitous in\nmolecular and biological systems, and are expected to affect both the diffusive\nmotion and (biological) function of dispersed objects. The recent development\nof colloidal structures with freely-jointed bonds have now made a direct\nexperimental investigation of diffusive shape-changing objects possible. Here,\nwe show the effect of segmental flexibility on the simplest possible model\nsystem, a freely-jointed cluster of three spherical particles, and validate\nlong-standing theoretical predictions. We find that in addition to the\nrotational diffusion time, an analogous conformational diffusion time governs\nthe relaxation of the diffusive motion, unique to flexible assemblies, and that\ntheir translational diffusivity differs by a small but measurable amount. We\nalso uncovered a Brownian quasiscallop mode, where diffusive motion is coupled\nto Brownian shape changes. Our findings could have implications for molecular\nand biological systems where diffusion plays an important role, such as\nfunctional site availability in lock-and-key protein interactions."
    },
    {
        "anchor": "Rectification of polymer translocation through nanopores by chiral and\n  nonchiral active particles: We study unbiased translocation of a flexible polymer chain through a\nmembrane pore under the influence of active noise and steric exclusion using\nLangevin dynamics simulations. The active noise is incorporated by introducing\nnonchiral and chiral active particles on one or both sides of the membrane.\nTranslocation of the polymer into either side of the pore is assisted by an\neffective pulling due to particle activity and is hindered by an effective\npushing due to steric repulsions between the polymer and active particles. As a\nresult of the competition between these effective forces, we find a transition\nbetween two rectified ({\\em cis}-to-{\\em trans} and {\\em trans}-to-{\\em cis})\nstates. This transition is identified by a sharp increase of translocation\ntime. It varies depending on the system parameters such as particle activity,\narea fraction and chirality whose effects are explored in this work.",
        "positive": "Flexible confinement leads to multiple relaxation regimes in glassy\n  colloidal liquids: Understanding relaxation of supercooled fluids is a major challenge and\nconfining such systems can lead to bewildering behaviour. Here we exploit an\noptically confined colloidal model system in which we use reduced pressure as a\ncontrol parameter. The dynamics of the system are ``Arrhenius'' at low and\nmoderate pressure, but at higher pressures relaxation is faster than expected.\nWe associate this faster relaxation with a decrease in density adjacent to the\nconfining boundary due to local ordering in the system enabled by the flexible\nwall."
    },
    {
        "anchor": "Force percolation of contractile active gels: Cells and tissues exert forces and can actively change shape. This strikingly\nautonomous behavior is powered by the cytoskeleton, which includes an active\ngel of actin filaments, crosslinks, and myosin molecular motors. Although\nindividual motors are only a few nm in size and exert minute forces of a few\npN, cells spatially integrate the activity of an ensemble of motors to produce\nlarger contractile forces (order nN and greater) on cellular, tissue, and\norganismal length scales (order 10 ${\\mu}$m and greater). Experimental studies\nof reconstituted active-network model systems have long suggested that a\nmechanical interplay between the network's connectivity and motor activity\ndominates contractile behavior. Recent theoretical models indicate that this\ninterplay can be understood in terms of percolation models, where the network\nconnectivity is influenced by motor activity. Here we review experimental and\ntheoretical studies of model contractile active gels and propose a state\ndiagram that unites a large body of experimental and theoretical observations\nbased on concepts from percolation theory.",
        "positive": "Chain Ends and the Ultimate Strength of Polyethylene Fibers: We use large scale molecular dynamics (MD) simulations to determine the\ntensile yield mechanism of orthorhombic polyethylene (PE) crystals with finite\nchains spanning $10^2-10^4$ carbons in length. We find the yield stress\n$\\sigma_y$ saturates for long chains at 6.3 GPa, agreeing well with\nexperiments. We show chains do not break but always yield by slip, after\nnucleation of 1D dislocations at chain ends. Dislocations are accurately\ndescribed by a Frenkel-Kontorova model parametrized by the mechanical\nproperties of an ideal crystal. We compute a dislocation core size\n$\\xi\\approx25$\\AA\\ and determine the high and low strain rate limits of\n$\\sigma_y$. Our results suggest characterizing the 1D dislocations of polymer\ncrystals as an efficient method for numerically predicting the ultimate tensile\nstrength of aligned fibers."
    },
    {
        "anchor": "Dynamical Janssen effect on granular packings with moving walls: Apparent mass measurements at the bottom of granular packings inside a\nvertical tube in relative motion are reported. They demonstrate that Janssen's\nmodel is valid over a broad range of velocities v. The variability of the\nmeasurements is lower than for static packings and the theoretical exponential\nincrease of the apparent mass with the height of the packing is precisely\nfollowed (the corresponding characteristic screening length is of the order of\nthe tube diameter). The limiting apparent mass at large heights is independent\nof v and significantly lower than the static value.",
        "positive": "Edge wetting of an Ising three-dimensional system: The effect of edge on wetting and layering transitions of a three-dimensional\nspin-1/2 Ising model is investigated, in the presence of longitudinal and\nsurface magnetic fields, using mean field (MF) theory and Monte Carlo (MC)\nsimulations. For T=0, the ground state phase diagram shows that there exist\nonly three allowed transitions, namely: surface and bulk transition, surface\ntransition and bulk transition. However, there exist a surface intra-layering\ntemperature $T_{L}^{s}$, above which the surface and the intra-layering surface\ntransitions occur. While the bulk layering and intra-layering transitions\nappear above an other finite temperature $T_{L}^{b} (\\ge T_{L}^{s})$. These\nsurface and bulk intra-layering transitions are not seen in the perfect\nsurfaces case.\n  Numerical values of $T_{L}^{s}$ and $T_{L}^{b}$, computed by Monte Carlo\nmethod are found to be smaller than those obtained using mean field theory.\nHowever, the results predicted by the two methods become similar, and are\nexactly those given by the ground state phase diagram, for very low\ntemperatures. On the other hand, the behavior of the local magnetizations as a\nfunction of the external magnetic field, shows that the transitions are of the\nfirst order type. $T_{L}^{s}$ and $T_{L}^{b}$ decrease when increasing the\nsystem size and/or the surface magnetic field. In particular, $T_{L}^{b}$\nreaches the wetting temperature $T_{w}$ for sufficiently large system sizes."
    },
    {
        "anchor": "Universal monomer dynamics of a two dimensional semi-flexible chain: We present a unified scaling theory for the dynamics of monomers for dilute\nsolutions of semiflexible polymers under good solvent conditions in the free\ndraining limit. Our theory encompasses the well-known regimes of mean square\ndisplacements (MSDs) of stiff chains growing like t^{3/4} with time due to\nbending motions, and the Rouse-like regime t^{2 \\nu / (1+ 2\\nu)} where \\nu is\nthe Flory exponent describing the radius R of a swollen flexible coil. We\nidentify how the prefactors of these laws scale with the persistence length\nl_p, and show that a crossover from stiff to flexible behavior occurs at a MSD\nof order l^2_p (at a time proportional to l^3_p). A second crossover (to\ndiffusive motion) occurs when the MSD is of order R^2. Large scale Molecular\nDynamics simulations of a bead-spring model with a bond bending potential\n(allowing to vary l_p from 1 to 200 Lennard-Jones units) provide compelling\nevidence for the theory, in D=2 dimensions where \\nu=3/4. Our results should be\nvaluable for understanding the dynamics of DNA (and other semiflexible\nbiopolymers) adsorbed on substrates.",
        "positive": "Thermodynamics of condensed matter with strong pressure-energy\n  correlations: We show that for any liquid or solid with strong correlation between its\n$NVT$ virial and potential-energy equilibrium fluctuations, the temperature is\na product of a function of excess entropy per particle and a function of\ndensity, $T=f(s)h(\\rho)$. This implies that 1) the system's isomorphs (curves\nin the phase diagram of invariant structure and dynamics) are described by\n$h(\\rho)/T={\\rm Const.}$, 2) the density-scaling exponent is a function of\ndensity only, 3) a Gr{\\\"u}neisen-type equation of state applies for the\nconfigurational degrees of freedom. For strongly correlating atomic systems one\nhas $h(\\rho)=\\sum_nC_n\\rho^{n/3}$ in which the only non-zero terms are those\nappearing in the pair potential expanded as $v(r)=\\sum_n v_n r^{-n}$. Molecular\ndynamics simulations of Lennard-Jones type systems confirm the theory."
    },
    {
        "anchor": "Evidence of a low-temperature dynamical transition in concentrated\n  microgels: A low-temperature dynamical transition has been reported in several proteins.\nWe provide the first observation of a `protein-like' dynamical transition in\nnonbiological aqueous environments. To this aim we exploit the popular\ncolloidal system of poly-N-isopropylacrylamide (PNIPAM) microgels, extending\ntheir investigation to unprecedentedly high concentrations. Owing to the\nheterogeneous architecture of the microgels, water crystallization is avoided\nin concentrated samples, allowing us to monitor atomic dynamics at low\ntemperatures. By elastic incoherent neutron scattering and molecular dynamics\nsimulations, we find that a dynamical transition occurs at a temperature\n$T_d\\sim250$~K, independently from PNIPAM mass fraction. However, the\ntransition is smeared out on approaching dry conditions. The quantitative\nagreement between experiments and simulations provides evidence that the\ntransition occurs simultaneously for PNIPAM and water dynamics. The similarity\nof these results with hydrated protein powders suggests that the dynamical\ntransition is a generic feature in complex macromolecular systems,\nindependently from their biological function.",
        "positive": "Period proliferation in periodic states in cyclically sheared jammed\n  solids: Athermal disordered systems can exhibit a remarkable response to an applied\noscillatory shear: after a relatively few shearing cycles, the system falls\ninto a configuration that had already been visited in a previous cycle. After\nthis point the system repeats its dynamics periodically despite undergoing many\nparticle rearrangements during each cycle. We study the behavior of orbits as\nwe approach the jamming point in simulations of jammed particles subject to\noscillatory shear at fixed pressure and zero temperature. As the pressure is\nlowered, we find that it becomes more common for the system to find periodic\nstates where it takes multiple cycles before returning to a previously visited\nstate. Thus, there is a proliferation of longer periods as the jamming point is\napproached."
    },
    {
        "anchor": "Failure of confined granular media due to pullout of an intruder: From\n  force networks to a system wide response: We investigate computationally the pullout of a spherical intruder initially\nburied at the bottom of a granular column. The intruder starts to move out of\nthe granular bed once the pulling force reaches a critical value, leading to\nmaterial failure. The failure point is found to depend on the diameter of the\ngranular column, pointing out the importance of particle-wall interaction in\ndetermining the material response. Discrete element simulations show that prior\nto failure, the contact network is essentially static, with only minor\nrearrangements of the particles. However, the force network, which includes not\nonly the contact information, but also the information about the interaction\nstrength, undergoes a nontrivial evolution. An initial insight is reached by\nconsidering the relative magnitudes of normal and tangential forces between the\nparticles, and in particular the proportion of contacts that reach Coulomb\nthreshold. More detailed understanding of the processes leading to failure is\nreached by the analysis of both spatial and temporal properties of the force\nnetwork using the tools of persistent homology. We find that the forces between\nthe particles undergo intermittent temporal variations ahead of the failure. In\naddition to this temporal intermittency, the response of the force network is\nfound to be spatially dependent and influenced by proximity to the intruder.\nFurthermore, the response is modified significantly by the interaction\nstrength, with the relevant measures describing the response showing differing\nbehavior for the contacts characterized by large interaction forces.",
        "positive": "Density scaling of the diffusivity in viscous liquids: Identification of\n  the scaling exponent with the pressure derivative of the isothermal bulk\n  modulus: A density scaled diffusivity function for viscous liquids derived earlier\n[Phys. Rev. E 79, 032501 (2009)] is revisited, based on an improved equation of\nstate assuming that the isothermal bulk modulus increases linearly with\npressure. Without making any assumption on the interconnection between the\nscaling exponent and the Gruneisen parameter, we prove that the scaling\nexponent is identical with the pressure derivative of the isothermal bulk\nmodulus. We further discuss probable interconnection between the scaling\nexponent and the Gruneisen parameter.meter."
    },
    {
        "anchor": "Surface impacts and collisions of particle-laden nanodrops: The surface impact and collisions of particle-laden nanodrops are studied\nusing molecular dynamics computer simulations. The drops are composed of\nLennard- Jones dimers and the particles are rigid spherical sections of a cubic\nlattice, with radii about 11 nm and 0.6 nm, respectively. Uniform suspensions\nof 21% and 42% particle concentrations and particle-coated drops are studied,\nand their behavior is compared to that of pure fluid drops of the same size.\nThe relative velocities studied span the transition to splashing, and both\nwetting/miscible and non-wetting/immiscible cases are considered. Impacts\nnormal to the surface and head-on collisions are studied and compared. In\nsurface impact, the behavior of low-density suspensions and liquid marble drops\nis qualitatively similar to that of pure liquid, while the concentrated drops\nare solid-like on impact. Collisions produce a splash only at velocities\nsignif- icantly higher than in impact, but the resulting drop morphology shows\na similar dependence on solid concentration as in impact. In all cases the\ncollision or impact produces a strong local enhancement in the kinetic energy\ndensity and temperature but not in the particle or potential energy densities.\nMixing of the two colliding species is not enhanced by collisions, unless the\nvelocity is so high as to cause drop disintegration.",
        "positive": "M\u00e9thodes quasi-statiques pour la simulation num\u00e9rique discr\u00e8te des\n  assemblages granulaires: Useful definitions and properties pertaining to static granular packings, in\nwhich a contact network is able to support externally applied forces and\nmaintain equilibrium for varying loads, are reviewed and discussed. It is\nexplained how one may then compute force variations and displacements without\nintroducing inertia or any time-dependent forces."
    },
    {
        "anchor": "Hydrodynamic Synchronisation of Chiral Microswimmers: We study synchronization in bulk suspensions of spherical microswimmers with\nchiral trajectories using large scale numerics. The model is generic. It\ncorresponds to the lowest order solution of a general model for self-propulsion\nat low Reynolds numbers, consisting of a nonaxisymmetric rotating source\ndipole. We show that both purely circular and helical swimmers can\nspontaneously synchronize their rotation. The synchronized state corresponds to\nvelocity alignment with high orientational order in both the polar and\nazimuthal directions. Finally, we consider a racemic mixture of helical\nswimmers where intraspecies synchronization is observed while the system\nremains as a spatially uniform fluid. Our results demonstrate hydrodynamic\nsynchronization as a natural collective phenomenon for microswimmers with\nchiral trajectories.",
        "positive": "Random networks of cross-linked directed polymers: We explore the effect of random permanent cross-links on a system of directed\npolymers confined between two planes with their end-points free to slide on\nthem. We treat the cross-links as quenched disorder and we use a\nsemimicroscopic replica field theory to study the structure and elasticity of\nthis system. Upon increasing the cross-link density, we get a continuous\ngelation transition signaled by the emergence of a finite in-plane localization\nlength. The distribution of localization length turns out to depend on the\nheight along the preferred direction of the directed polymers. The gelation\ntransition also gives rise to a finite in-plane shear modulus which we\ncalculate and turns out to be universal, i.e., independent of the energy and\nlength scales of the polymers and the cross-links. Using a symmetry argument,\nwe show that cross-links of negligible extent along the preferred axis of the\ndirected polymers do not cause any renormalization to the tilt modulus of the\nuncross-linked system."
    },
    {
        "anchor": "Dirt Softens Soap: Anomalous Elasticity of Disordered Smectics: We show that a smectic in a disordered medium (e.g., aerogel) exhibits\nanomalous elasticity, with the compression modulus B(k) vanishing and the bend\nmodulus K(k) diverging as k --> 0. In addition, the effective disorder develops\nlong ranged correlations. These divergences are much stronger than those driven\nby thermal fluctuations in pure smectics, and are controlled by a zero\ntemperature glassy fixed point, which we study in an $\\epsilon=5-d$ expansion.\nWe discuss the experimental implications of these theoretical predictions.",
        "positive": "Response to Comment on Repulsive contact interactions make jammed\n  particulate systems inherently nonharmonic': This is a response to the comment on our manuscript \"Repulsive contact\ninteractions make jammed particulate systems inherently nonharmonic\" (Physical\nReview Letters 107 (2011) 078301) by C. P. Goodrich, A. J. Liu, and S. R.\nNagel."
    },
    {
        "anchor": "Direct evidence of stress-induced chain proximity in a macromolecular\n  complex: The mechanical properties of many supramolecular materials are often\ndetermined by non-covalent interactions that arise from an interplay between\nchemical composition and molecular microstructural organization. The reversible\nnature of non-covalent interactions gives supramolecular materials responsive\nproperties that are otherwise difficult to obtain, such as becoming rigid as a\nresponse to mechanical stress. How exactly non-covalent interactions emerge\nfrom microstructure, how they might change in response to applied force or\ndeformation is not understood. Here we combine Nuclear Magnetic Resonance (NMR)\nand rheology to directly probe the role of chain proximity in polymer\ncomplexes. We observe an increase in chain proximity in response to imposed\nflow, which we hypothesize to originate from enhanced hydrogen bonding. The\nchain proximity is directly correlated to rod climbing and shear banding. Flow\npersists only when applied stresses are low, suggesting a stress-induced\nthickening mechanism. We verify that hydrogen bond disruptors can turn off both\nthe non-trivial flow behavior and the spectroscopic evidence of chain\nproximity. The combined rheo-NMR approach shows that it is possible to directly\nobserve the molecular origins behind supramolecular mechanics, paving the way\nfor further study into mechano-chemical properties of supramolecular materials.",
        "positive": "Bimodality in the transverse fluctuations of a grafted semiflexible\n  polymer and the diffusion-convection analogue: an effective-medium approach: Recent Monte Carlo simulations of a grafted semiflexible polymer in 1+1\ndimensions have revealed a pronounced bimodal structure in the probability\ndistribution of the transverse (bending) fluctuations of the free end, when the\ntotal contour length is of the order of the persistence length [G. Lattanzi et\nal., Phys. Rev E 69, 021801 (2004)]. In this paper, we show that the emergence\nof bimodality is related to a similar behavior observed when a random walker is\ndriven in the transverse direction by a certain type of shear flow. We adapt an\neffective-medium argument, which was first introduced in the context of the\nsheared random-walk problem [E. Ben-Naim et al., Phys. Rev. A 45, 7207 (1992)],\nin order to obtain a simple analytic approximation of the probability\ndistribution of the free-end fluctuations. We show that this approximation\ncaptures the bimodality and most of the qualitative features of the free-end\nfluctuations. We also predict that relaxing the local inextensibility\nconstraint of the wormlike chain could lead to the disappearence of bimodality."
    },
    {
        "anchor": "Biotransformation and biological impact of graphene and graphene oxide\n  during simulated oral ingestion: Graphene is an innovative nanomaterial, made of two-dimensional\nhoneycomb-like carbon lattice, with potential in many different applications.\nStudying the behaviour of graphene-related materials (GRMs) in biological\nsystems is, therefore, crucial to assess possible side effects. In this work is\nstudied the biotransformation and biological impact of few-layer pristine\ngraphene (FLG) and graphene oxide (GOX), following ingestion as exposure route.\nTo mimic FLG and GOX ingestion, an in vitro digestion assay based on a\nstandardized operating procedure (SOP) is applied. The assay simulates the\nhuman ingestion of GRMs during their dynamic passage through the different\nenvironments of gastrointestinal (GI) tract (salivary, gastric, intestinal).\nPhysical-chemical changes of GRMs during the digestion process are assessed\nthrough a detailed Raman spectroscopy characterization. Moreover, the effect of\nchronic exposure to digested GRMs on integrity and functionality of an in vitro\nmodel of intestinal barrier is also determined according to a second SOP. Our\nresults showed that the FLG and GOX nanoflakes aggregates after experiencing\nthe passage through the different environments of GI tract, with evident doping\neffects, due to the interaction of GRMs with digestive juice components and the\nstrong pH variations. Interestingly, neither structural changes nor degradation\nof the nanomaterials is observed, suggesting that GRMs are bio-persistent\nnanomaterials when administered by oral route. Chronic exposure to digested\nGRMs does not affect intestinal barrier integrity and is not associated to\ninflammation and cytotoxicity, though possible long-term adverse effects cannot\nbe ruled out, due to the observed bio-durability of the materials.",
        "positive": "Surprising simplicity in the modeling of dynamic granular intrusion: Granular intrusions, such as dynamic impact or wheel locomotion, are complex\nmultiphase phenomena where the grains exhibit solid-like and fluid-like\ncharacteristics together with an ejected gas-like phase. Despite decades of\nmodeling efforts, a unified description of the physics in such intrusions is as\nyet unknown. Here we show that a continuum model based on the simple notions of\nfrictional flow and tension-free separation describes complex granular\nintrusions near free surfaces. This model captures dynamics in a variety of\nexperiments including wheel locomotion, plate intrusions, and running legged\nrobots. The model reveals that three effects (a static contribution and two\ndynamic ones) primarily give rise to intrusion forces in such scenarios.\nIdentification of these effects enables the development of a further\nreduced-order technique (Dynamic Resistive Force Theory) for rapid modeling of\ngranular locomotion of arbitrarily shaped intruders. The continuum-motivated\nstrategy we propose for identifying physical mechanisms and corresponding\nreduced-order relations has potential use for a variety of other materials."
    },
    {
        "anchor": "Singular Energy Distributions in Granular Media: We study the kinetic theory of driven granular gases, taking into account\nboth translational and rotational degrees of freedom. We obtain the high-energy\ntail of the stationary bivariate energy distribution, depending on the total\nenergy E and the ratio x=sqrt{E_w/E} of rotational energy E_w to total energy.\nExtremely energetic particles have a unique and well-defined distribution f(x)\nwhich has several remarkable features: x is not uniformly distributed as in\nmolecular gases; f(x) is not smooth but has multiple singularities. The latter\nbehavior is sensitive to material properties such as the collision parameters,\nthe moment of inertia and the collision rate. Interestingly, there are\npreferred ratios of rotational-to-total energy. In general, f(x) is strongly\ncorrelated with energy and the deviations from a uniform distribution grow with\nenergy. We also solve for the energy distribution of freely cooling Maxwell\nMolecules and find qualitatively similar behavior.",
        "positive": "Dynamics of the variation of shape of the hysteresis of stress-strain\n  cyclic compression curves registered at the investigations of the mechanical\n  behavior of composite hydrogels: An unusual type of mechanical behavior was registered while studying the\nswollen hydrogel compositions \"cellulose-polyacrylamide\" in the conditions of\nmultiple cyclic compression tests with the broad variation of the deformation\nspeed. While increasing the deformation speed the clearly seen inversion of the\npositions of compression and decompression parts of the cyclic stress-strain\ncurves was detected. While carrying out the cyclic compression tests with\nrelatively low deformation speed (about 100-200 % of the initial sample's\nheight per minute) the well defined hysteresis of the stress-strain curve can\nde seen and in these conditions the decompression part of the curve is situated\ninferior the part corresponding to compression. But while increasing the speed\nof the deformation the tendency to the progressive approach of the compression\nand decompression curves to each other is clearly seen. This effect results in\nthe full disappearance of the hysteresis at some value of the deformation\nspeed: the decompression curve coincides with the compression curve. Along with\nthe further increase of the deformation speed the hysteresis appears again but\nthe curve corresponding to compression process is situated inferior the curve\ncorresponding to decompression: the \"inversion\" of the hysteresis was detected.\nThe precise character of this process depends upon the stiffness of the\nhydrogel under study. Up to date the convincing explanation of this effect can\nnot been put forward. The authors can only present some hypotheses to explain\nthis phenomenon."
    },
    {
        "anchor": "Modeling planar degenerate wetting and anchoring in nematic liquid\n  crystals: We propose a simple surface potential favoring the planar degenerate\nanchoring of nematic liquid crystals, i.e., the tendency of the molecules to\nalign parallel to one another along any direction parallel to the surface. We\nshow that, at lowest order in the tensorial Landau-de Gennes order-parameter,\nfourth-order terms must be included. We analyze the anchoring and wetting\nproperties of this surface potential. In the nematic phase, we find the desired\ndegenerate planar anchoring, with positive scalar order-parameter and some\nsurface biaxiality. In the isotropic phase, we find, in agreement with\nexperiments, that the wetting layer may exhibit a uniaxial ordering with\nnegative scalar order-parameter. For large enough anchoring strength, this\nnegative ordering transits towards the planar degenerate state.",
        "positive": "The Stokes-Einstein Relation at Moderate Schmidt Number: The Stokes-Einstein relation for the self-diffusion coefficient of a\nspherical particle suspended in an incompressible fluid is an asymptotic result\nin the limit of large Schmidt number, that is, when momentum diffuses much\nfaster than the particle. When the Schmidt number is moderate, which happens in\nmost particle methods for hydrodynamics, deviations from the Stokes-Einstein\nprediction are expected. We study these corrections computationally using a\nrecently-developed minimally-resolved method for coupling particles to an\nincompressible fluctuating fluid in both two and three dimensions. We find that\nfor moderate Schmidt numbers the diffusion coefficient is reduced relative to\nthe Stokes-Einstein prediction by an amount inversely proportional to the\nSchmidt number in both two and three dimensions. We find, however, that the\nEinstein formula is obeyed at all Schmidt numbers, consistent with linear\nresponse theory. The numerical data is in good agreement with an approximate\nself-consistent theory, which can be used to estimate finite-Schmidt number\ncorrections in a variety of methods. Our results indicate that the corrections\nto the Stokes-Einstein formula come primarily from the fact that the particle\nitself diffuses together with the momentum. Our study separates effects coming\nfrom corrections to no-slip hydrodynamics from those of finite separation of\ntime scales, allowing for a better understanding of widely observed deviations\nfrom the Stokes-Einstein prediction in particle methods such as molecular\ndynamics."
    },
    {
        "anchor": "Direct calculation of the planar NaCl-aqueous solution interfacial free\n  energy at the solubility limit: Salty water is the most abundant electrolyte aqueous mixture on Earth,\nhowever, very little is known about the NaCl-saturated solution interfacial\nfree energy. Here, we provide the first direct estimation of this magnitude for\nseveral NaCl crystallographic planes by means of the Mold Integration\ntechnique, a highly efficient computational method to evaluate interfacial free\nenergies with anisotropic crystal resolution. Making use of the JC-SPC/E model,\none of the most benchmarked force fields for NaCl/water solutions, we measure\nthe interfacial free energy of four different planes, (100), (110), (111), and\n(11-2) with the saturated solution at normal conditions. We find high\nanisotropy between the different crystal orientations with values ranging from\n100 to 150 mJ/m2 and the average value of the distinct planes being 137(20)\nmJ/m2. This value for the coexistence interfacial free energy is in reasonable\nagreement with previous extrapolations from nucleation studies. Our work\nrepresents a milestone in the computational calculation of interfacial free\nenergies between ionic crystals and aqueous solutions.",
        "positive": "Are granular materials simple? An experimental study of strain gradient\n  effects and localization: Experiments test the dependence of shearing stress on the first two gradients\nof shear strain. The tests were conducted by direct numerical simulation using\nthe Discrete Element Method (DEM) on a large two-dimensional (2D) assembly of\ncircular disks. The assembly was coerced into non-uniformly deformed shapes by\napplying body forces to the material region. The tests show that shearing\nstress is affected by both the first and second gradients of shear strain, and\nthe measured responses to strain and its gradients are all incrementally\nnon-linear. The dilation rate is unaffected by strain gradients. Particle\nrotations, although highly erratic, are, on average, consistent with the\nmean-field rotation and unaffected by strain gradients. In independent\nunconstrained tests, the material was sheared without body forces so that\nlocalization could freely occur. Three localization patterns were observed:\nmicrobands at very small strains; non-persistent shear bands at moderate\nstrains; and persistent bands at large strains. The observed features of\nmicrobands and shear bands are consistent with the measured influences of\nshearing strain and its first two derivatives."
    },
    {
        "anchor": "Different glassy characteristics are related to either caging or\n  dynamical heterogeneity: Despite the enormous theoretical and application interests, a fundamental\nunderstanding of the glassy dynamics remains elusive. The static properties of\nglassy and ordinary liquids are similar, but their dynamics are dramatically\ndifferent. What leads to this difference is the central puzzle of the field.\nEven the primary defining glassy characteristics, their implications, and if\nthey are related to a single mechanism remain unclear. This lack of clarity is\na severe hindrance to theoretical progress. Here, we combine analytical\narguments and simulations of various systems in different dimensions and\naddress these questions. Our results suggest that the myriad of glassy features\nare manifestations of two distinct mechanisms. Particle caging controls the\nmean, and coexisting slow- and fast-moving regions govern the distribution of\nparticle displacements. All the other glassy characteristics are manifestations\nof these two mechanisms; thus, the Fickian yet non-Gaussian nature of glassy\nliquids is not surprising. Our results have crucial implications on how the\nglassy dynamics data are analyzed, challenge some recent suggestions on the\nmechanisms governing gassy dynamics, and impose strict constraints that a\ncorrect theory of glasses must have.",
        "positive": "Glassy behaviour of sticky spheres: What lies beyond experimental\n  timescales?: We use the swap Monte Carlo algorithm to analyse the glassy behaviour of\nsticky spheres in equilibrium conditions at densities where conventional\nsimulations and experiments fail to reach equilibrium, beyond predicted phase\ntransitions and dynamic singularities. We demonstrate the existence of a unique\nergodic region comprising all the distinct phases previously reported, except\nfor a phase-separated region at strong adhesion. All structural and dynamic\nobservables evolve gradually within this ergodic region, the physics evolving\nsmoothly from well-known hard sphere glassy behaviour at small adhesions and\nlarge densities, to a more complex glassy regime characterised by\nunusually-broad distributions of relaxation timescales and lengthscales at\nlarge adhesions."
    },
    {
        "anchor": "Programming complex shapes in thin nematic elastomer and glass sheets: Nematic elastomers and glasses are solids that display spontaneous distortion\nunder external stimuli. Recent advances in the synthesis of sheets with\ncontrolled heterogeneities have enabled their actuation into non-trivial shapes\nwith unprecedented energy density. Thus, these have emerged as powerful\ncandidates for soft actuators. To further this potential, we introduce the key\nmetric constraint which governs shape changing actuation in these sheets. We\nthen highlight the richness of shapes amenable to this constraint through two\nbroad classes of examples which we term nonisometric origami and lifted\nsurfaces. Finally, we comment on the derivation of the metric constraint, which\narises from energy minimization in the interplay of stretching, bending and\nheterogeneity in these sheets.",
        "positive": "Reconfigurable interactions and three-dimensional patterning of\n  colloidal particles and defects in lamellar soft media: Colloidal systems find important applications ranging from fabrication of\nphotonic crystals to direct probing of phenomena typically encountered in\natomic crystals and glasses. New applications - such as nanoantennas, plasmonic\nsensors, and nanocircuits - pose a challenge of achieving sparse colloidal\nassemblies with tunable interparticle separations that can be controlled at\nwill. We demonstrate reconfigurable multiscale interactions and assembly of\ncolloids mediated by defects in cholesteric liquid crystals that are probed by\nmeans of laser manipulation and three-dimensional imaging. We find that\ncolloids attract via distance-independent elastic interactions when pinned to\nthe ends of cholesteric oily streaks, line defects at which one or more layers\nare interrupted. However, dislocations and oily streaks can also be optically\nmanipulated to induce kinks, allowing one to lock them into the desired\nconfigurations that are stabilized by elastic energy barriers for structural\ntransformation of the particle-connecting defects. Under the influence of\nelastic energy landscape due to these defects, sublamellar-sized colloids\nself-assemble into structures mimicking the cores of dislocations and oily\nstreaks. Interactions between these defect embedded colloids can be varied from\nattractive to repulsive by optically introducing dislocation kinks. The\nreconfigurable nature of defect-particle interactions allows for patterning of\ndefects by manipulation of colloids and, in turn, patterning of particles by\nthese defects, thus achieving desired colloidal configurations on scales\nranging from the size of defect core to the sample size. This defect-colloidal\nsculpturing may be extended to other lamellar media, providing the means for\noptically guided self-assembly of mesoscopic composites with predesigned\nproperties."
    },
    {
        "anchor": "Relaxation kinetics of biological dimer adsorption models: We discuss the relaxation kinetics of a one-dimensional dimer adsorption\nmodel as recently proposed for the binding of biological dimers like kinesin on\nmicrotubules. The non-equilibrium dynamics shows several regimes: irreversible\nadsorption on short time scales, an intermediate plateau followed by a\npower-law regime and finally exponential relaxation towards equilibrium. In all\nfour regimes we give analytical solutions. The algebraic decay and the scaling\nbehaviour can be explained by mapping onto a simple reaction-diffusion model.\nWe show that there are several possibilities to define the autocorrelation\nfunction and that they all asymptotically show exponential decay, however with\ndifferent time constants. Our findings remain valid if there is an attractive\ninteraction between bound dimers.",
        "positive": "Deposition and alignment of fiber suspensions by dip coating: The dip coating of suspensions made of monodisperse non-Brownian spherical\nparticles dispersed in a Newtonian fluid leads to different coating regimes\ndepending on the ratio of the particle diameter to the thickness of the film\nentrained on the substrate. In particular, dilute particles dispersed in the\nliquid are entrained only above a threshold value of film thickness. In the\ncase of anisotropic particles, in particular fibers, the smallest\ncharacteristic dimension will control the entrainment of the particle.\nFurthermore, it is possible to control the orientation of the anisotropic\nparticles depending on the substrate geometry. To test the hypotheses, we\nperformed dip-coating experiments with dilute suspensions of non-Brownian\nfibers with different length-to-diameter aspect ratios. We characterize the\nnumber of fibers entrained on the surface of the substrate as a function of the\nwithdrawal velocity, allowing us to estimate a threshold capillary number below\nwhich all the particles remain in the liquid bath. Besides, we measure the\nangular distribution of the entrained fibers for two different substrate\ngeometries: flat plates and cylindrical rods. We then measure the film\nthickness for more concentrated fiber suspensions. The entrainment of the\nfibers on a flat plate and a cylindrical rod is primarily controlled by the\nsmaller characteristic length of the fibers: their diameter. At first order,\nthe entrainment threshold scales similarly to that of spherical particles. The\nlength of the fibers only appears to have a minor influence on the entrainment\nthreshold. No preferential alignment is observed for non-Brownian fibers on a\nflat plate, except for very thin films, whereas the fibers tend to align\nthemselves along the axis of a cylindrical rod for a large enough ratio of the\nfiber length to the radius of the cylindrical rod."
    },
    {
        "anchor": "How do interfaces alter the dynamics of supercooled water?: The structure of liquid water in the proximity of an interface can deviate\nsignificantly from that of bulk water, with surface-induced structural\nperturbations typically converging to bulk values at about ~1 nm from the\ninterface. While these structural changes are well established it is, in\ncontrast, less clear how an interface perturbs the dynamics of water molecules\nwithin the liquid. Here, through an extensive set of molecular dynamics\nsimulations of supercooled bulk and interfacial water films and nano-droplets,\nwe observe the formation of persistent, spatially extended dynamical domains in\nwhich the average mobility varies as a function of the distance from the\ninterface. This is in stark contrast with the dynamical heterogeneity observed\nin bulk water, where these domains average out spatially over time. We also\nfind that the dynamical response of water to an interface depends critically on\nthe nature of the interface and on the choice of interface definition. Overall\nthese results reveal a richness in the dynamics of interfacial water that opens\nup the prospect of tuning the dynamical response of water through specific\nmodifications of the interface structure or confining material.",
        "positive": "Stretching an adsorbed polymer globule: Using molecular dynamic simulation, we study the stretching of an adsorbed\nhomopolymer in a poor solvent with one end held at a distance $z_e$ from the\nsubstrate. We measure the vertical force $f$ on the end of the chain as a\nfunction of the extension $z_e$ and the substrate interaction energy $w$. The\nforce reaches a plateau value at large extensions. In the strong adsorption\nlimit, we show that the plateau value increase linearly in $w$ in good\nagreement with a theoretical model. In the weak adsorption limit, a polymer\nglobule with a layered structure is formed and elastically deformed when\nstretched. In both cases a simple theoretical model permits us to predict the\nrelation between the necessary force to fully detach the polymer and its\ncritical extension."
    },
    {
        "anchor": "Monte Carlo simulation of colloidal particles dynamics in a drying drop: The work is devoted to particles dynamics simulation in a colloidal drop,\nwhen it dries on a substrate and the triple-phase boundary is fixed.\nExperimental observations [Deegan R. D. et. al., 2000] show a ring deposition\non a solid substrate after full droplet desiccation. This phenomenon of\nmacrolevel is known as coffee ring effect. There are other experiments that\nshow a co-effect at the microlevel. We are talking about the formation of a\nquasicrystalline structure on the outer part of the ring and occurrence\namorphous inner zone of ring [Mar\\'{\\i}n \\'A. G. et. al., 2011]. The goal of\nthis work is to check the hypothesis of other authors that this phenomenon is\nexplained by the competition between the characteristic times of diffusional\ndisplacement of particles and their transfer by a compensation flow [Mar\\'{\\i}n\n\\'A. G. et. al., 2011]. Numerical calculations using a model built on the basis\nof such assumptions and effects did not show the formation of a quasicrystal\nstructure. It is probably necessary to take into account additional effects in\nsuch a system, for example, surface tension.",
        "positive": "Self-Aligning Active Agents with Inertia and Active Torque: We extend the study of the inertial effects on the dynamics of active agents\nto the case where self-alignment is present. In contrast with the most common\nmodels of active particles, we find that self-alignment, which couples the\nrotational dynamics to the translational one, produces unexpected and\nnon-trivial dynamics, already at the deterministic level. Examining first the\nmotion of a free particle, we contrast the role of inertia depending on the\nsign of the self-aligning torque. When positive, inertia does not alter the\nsteady-state linear motion of an a-chiral self-propelled particle. On the\ncontrary, for a negative self-aligning torque, inertia leads to the\ndestabilization of the linear motion into a spontaneously broken chiral\nsymmetry orbiting dynamics. Adding an active torque, or bias, to the angular\ndynamics the bifurcation becomes imperfect in favor of the chiral orientation\nselected by the bias. In the case of a positive self-alignment, the interplay\nof the active torque and inertia leads to the emergence, out of a saddle-node\nbifurcation, of truly new solutions, which coexist with the simply biased\nlinear motion. In the context of a free particle, the rotational inertia leaves\nunchanged the families of steady-state solutions but can modify their stability\nproperties. The situation is radically different when considering the case of a\ncollision with a wall, where a very singular oscillating dynamics takes place\nwhich can only be captured if both translational and rotational inertia are\npresent."
    },
    {
        "anchor": "Critical-like gelation dynamics in cellulose nanocrystal suspensions: We use time-resolved mechanical spectroscopy to offer a detailed picture of\nthe gelation dynamics of cellulose nanocrystal (CNC) suspensions following\nshear cessation in the presence of salt. CNCs are charged, rodlike colloids\nthat self-assemble into various phases, including physical gels serving as soft\nprecursors for biosourced composites. Here, a series of linear viscoelastic\nspectra acquired across the sol-gel transition of CNC suspensions are rescaled\nonto two master curves, that correspond to a viscoelastic liquid state prior to\ngelation and to a soft solid state after gelation. These two states are\nseparated by a critical gel point, where all rescaling parameters diverge in an\nasymmetric fashion, yet with exponents that obey hyperscaling relations\nconsistent with previous works on isotropic colloids and polymer gels. Upon\nvarying the salt content, we further show that these critical-like dynamics\nresult in both time-connectivity and time-concentration superposition\nprinciples.",
        "positive": "A classical field method for time dependent Bose condensed gases: We propose a method to study the time evolution of Bose condensed gases\nperturbed from an initial thermal equilibrium, based on the Wigner\nrepresentation of the $N$-body density operator. We show how to generate a\ncollection of random classical fields sampling the initial Wigner distribution\nin the number conserving Bogoliubov approximation. The fields are then evolved\nwith the time dependent Gross-Pitaevskii equation. We illustrate the method\nwith the damping of a collective excitation of a one-dimensional Bose gas."
    },
    {
        "anchor": "On detection and annihilation of spherical virus embedded in a fluid\n  matrix at low and moderate Reynolds number: Effect of high and low Reynolds number is studied on low frequency\nvibrational modes of a spherical virus embedded in the aqueous medium. We have\nused an analytical approach based on fluid dynamic and classical Lamb theory to\ncalculate the vibrational modes of a virus with material parameters of lysozyme\ncrystal in water. The obvious size effect on the vibrational modes is observed.\nThe estimated damping time which is of the order of picosecond varies with\nReynolds number and shows a high value for a critical Reynolds number. The\nstationary eigenfrequency regions are observed for every quantum number l and n\nsuggesting the most probable Re ranges for acoustic treatment of viruses in\norder to detect or annihilate the virus using corresponding viruswater\nconfiguration.",
        "positive": "Higher Order Evaluation of the Critical Temperature for Interacting\n  Homogeneous Dilute Bose Gases: We use the nonperturbative linear \\delta expansion method to evaluate\nanalytically the coefficients c_1 and c_2^{\\prime \\prime} which appear in the\nexpansion for the transition temperature for a dilute, homogeneous, three\ndimensional Bose gas given by T_c= T_0 \\{1 + c_1 a n^{1/3} + [ c_2^{\\prime}\n\\ln(a n^{1/3}) +c_2^{\\prime \\prime} ] a^2 n^{2/3} + {\\cal O} (a^3 n)\\}, where\nT_0 is the result for an ideal gas, a is the s-wave scattering length and n is\nthe number density. In a previous work the same method has been used to\nevaluate c_1 to order-\\delta^2 with the result c_1= 3.06. Here, we push the\ncalculation to the next two orders obtaining c_1=2.45 at order-\\delta^3 and\nc_1=1.48 at order-\\delta^4. Analysing the topology of the graphs involved we\ndiscuss how our results relate to other nonperturbative analytical methods such\nas the self-consistent resummation and the 1/N approximations. At the same\norders we obtain c_2^{\\prime\\prime}=101.4, c_2^{\\prime \\prime}=98.2 and\nc_2^{\\prime \\prime}=82.9. Our analytical results seem to support the recent\nMonte Carlo estimates c_1=1.32 \\pm 0.02 and c_2^{\\prime \\prime}= 75.7 \\pm 0.4."
    },
    {
        "anchor": "Non-isothermal model for the direct isotropic/smectic-A liquid\n  crystalline transition: An extension to a high-order model for the direct isotropic/smectic-A liquid\ncrystalline phase transition was derived to take into account thermal effects\nincluding anisotropic thermal diffusion and latent heat of phase-ordering.\nMulti-scale multi-transport simulations of the non-isothermal model were\ncompared to isothermal simulation, showing that the presented model extension\ncorrects the standard Landau-de Gennes prediction from constant growth to\ndiffusion-limited growth, under shallow quench/undercooling conditions.\nNon-isothermal simulations, where meta-stable nematic pre-ordering precedes\nsmectic-A growth, were also conducted and novel non-monotonic\nphase-transformation kinetics observed.",
        "positive": "A mechanically-derived contact model for adhesive elastic-perfectly\n  plastic particles. Part II: Contact under high compaction--adding a bulk\n  elastic response: In Part I of this two part series, we presented a multi-neighbor dependent\ncontact model for adhesive elastic-plastic particles built upon the method of\ndimensionality reduction that is valid for the elastic and fully-plastic\ncontact regimes. In this Part II, we complete the contact model by proposing a\ntreatment for the bulk elastic contact regime which is characterized by a rapid\nstiffening in the force-displacement curve as interstitial pore spaces vanish.\nA simple formulation is presented for an additional bulk elastic force. A novel\ncriterion for triggering this force (i.e. detecting the bulk elastic regime)\nrelated to the remaining free surface area of the particle is also given. This\nbulk elastic force is then superimposed with the force response given in Part I\nto achieve a contact model capable of capturing a variety of complex loadings.\nIn this way, the methodology for treating the bulk elastic regime presented\nhere stands independent of Part I and could be appended to any contact model.\nDirect comparison is made to finite element simulations showcasing bulk elastic\nresponses, revealing the accurate predictive capabilities of the contact model.\nNotably, the contact model is also demonstrated to detect and evolve contacts\ncaused purely by outward displacement of the free surface with good precision."
    },
    {
        "anchor": "Charged inclusion in nematic liquid crystals: We present a general theory of liquid crystals under inhomogeneous electric\nfield in a Ginzburg-Landau scheme. The molecular orientation can be deformed by\nelectric field when the dielectric tensor is orientation-dependent. We then\ninvestigate the influence of a charged particle on the orientation order in a\nnematic state. The director is aligned either along or perpendicular to the\nlocal electric field around the charge, depending on the sign of the dielectric\nanisotropy. The deformation becomes stronger with increasing the ratio $Ze/R$,\nwhere $Ze$ is the charge and $R$ is the radius of the particle. Numerical\nanalysis shows the presence of defects around the particle for large $Ze/R$.\nThey are nanometer-scale defects for microscopic ions. If the dielectric\nanisotropy is positive, a Saturn ring defect appears. If it is negative, a pair\nof point defects appear apart from the particle surface, each being connected\nto the surface by a disclination line segment.",
        "positive": "Correlation between rearrangements and soft modes in polymer glasses\n  during deformation and recovery: We explore the link between soft vibrational modes and local relaxation\nevents in polymer glasses during physical aging, active deformation at constant\nstrain rate, and subsequent recovery. A softness field is constructed out of\nthe superposition of the amplitudes of the lowest energy normal modes, and\nfound to predict up to 70% of the rearrangements. Overlap between softness and\nrearrangements increases logarithmically during aging and recovery phases as\nenergy barriers rise due to physical aging, while yielding rapidly rejuvenates\nthe overlap to that of a freshly prepared glass. In the strain hardening\nregime, correlations rise for uniaxial tensile deformation but not for simple\nshear. These trends can be explained by considering the differing degrees of\nlocalization of the soft modes in the two deformation protocols."
    },
    {
        "anchor": "On the composition dependence of thermodynamic, dynamic and dielectric\n  properties of water-methanol model mixtures. Molecular dynamics simulation\n  results: We have investigated thermodynamic and dynamic properties as well as the\ndielectric constant of water-metha\\-nol model mixtures in the entire range of\ncomposition by using constant pressure molecular dynamics simulations at\nambient conditions. The SPC/E and TIP4P/Ew water models are used in combination\nwith the OPLS united atom modelling for methanol. Changes of the average number\nof hydrogen bonds between particles of different species and of the fractions\nof differently bonded molecules are put in correspondence with the behavior of\nexcess mixing volume and enthalpy, of self-diffusion coefficients and\nrotational relaxation times. From the detailed analyses of the results obtained\nin this work, we conclude that an improvement of the description of an ample\nset of properties of water-methanol mixtures can possibly be reached, if a more\nsophisticated, carefully parameterized, e.g., all atom, model for methanol is\nused. Moreover, exploration of parametrization of the methanol force field,\nwith simultaneous application of different combination rules for methanol-water\ncross interactions, is required.",
        "positive": "Scaling, saturation, and upper bounds in the failure of topologically\n  interlocked structures: Topological Interlocking Structures (TIS) have been increasingly studied in\nthe past two decades. However, some fundamental questions concerning the\neffects of Young's modulus and the friction coefficient on the structural\nmechanics of the most common type of TIS application - centrally loaded slabs -\nare not yet clear. Here, we present a first-of-its-kind parametric study based\non the Level-Set-Discrete-element-Method that aims to clarify how these two\nparameters affect multiple aspects of the behavior and failure of\ncentrally-loaded TIS slabs. This includes the evolution of the structural\nresponse up to and including failure, the foremost structural response\nparameters, and the residual carrying capacity. We find that the structural\nresponse parameters in TIS slabs scale linearly with Young's modulus, that they\nsaturate with the friction coefficient, and that the saturated response\nprovides an upper-bound on the capacity of centrally loaded TIS slabs reported\nin the literature. This, together with additional findings, insights, and\nobservations, comprise a novel contribution to our understanding of the\ninterlocked structural form."
    },
    {
        "anchor": "Geometrical consequences of foam equilibrium: The equilibrium conditions impose nontrivial geometrical constraints on the\nconfigurations that a two-dimensional foam can attain. In the first place, the\nthree centers of the films that converge to a vertex have to be on a line, i.e.\nall vertices are aligned. Moreover an equilibrated foam must admit a reciprocal\nfigure. This means that it must be possible to find a set of points P_i on the\nplane, one per bubble, such that the segments (P_i P_j) are normal to the\ncorresponding foam films. It is furthermore shown that these constraints are\nequivalent to the requirement that the foam be a Sectional Multiplicative\nVoronoi Partition (SMVP). A SMVP is a cut with a two-dimensional plane, of a\nthree-dimensional Multiplicative Voronoi Partition. Thus given an arbitrary\nequilibrated foam, we can always find point-like sources (one per bubble) in\nthree dimensions that reproduce this foam as a generalized Voronoi partition.\nThese sources are the only degrees of freedom that we need in oder to fully\ndescribe the foam.",
        "positive": "Adsorption assisted translocation of a chain molecule through a pore in\n  a spherical vesicle: We analyze the free energy for translocation of a polymer from the outside of\na spherical vesicle to the inside. The process is assumed to be driven by the\nadsorption of the polymer on the inner surface of the vesicle. We argue that in\nthe case where the polymer is adsorbed on the outer surface too, the entropic\nbarrier for translocation is absent. We analyze the adsorption energy and find\nthe free energy profile for the process. We argue that the motion corresponds\nto a polymer crossing a region with a change in free energy per segment. Based\nupon our earlier analsis of the behaviour of kinks in such a problem, we\nconclude that the translocation can occur with a crossing time $t_{cross}\\sim\nN$."
    },
    {
        "anchor": "Annular cracks in thin films of nanoparticle suspensions drying on a\n  fiber: We report an experimental study of the crack pattern formed during the drying\nof a colloidal suspension. A horizontal fiber, which provides a one\ndimensional, boundary-free substrate, is coated by a film of micronic\nthickness. The geometry imposes a remarkable annular crack pattern and allowing\nprecise measurements of the crack spacing over a short range of film thickness\n(between 2 and 10 $\\mu$m) which varies linearly with the film height. We\ncompare our experimental data with a model proposed by Kitsunezaki which\nsuggests that the variation of the crack spacing with the film thickness\ndepends on the ratio between a critical stress at cracking and a critical\nstress for slipping on the substrate. By measuring the friction force of the\ncolloidal gels on a hydrophobic surface through a cantilever technique, we can\ndeduce the critical crack stress for these colloidal gels simply by measuring\nthe crack spacing of the pattern.",
        "positive": "Drag and diffusion coefficients of a spherical particle attached to a\n  fluid interface: Explicit analytical expressions for the drag and diffusion coefficients of a\nspherical particle attached to the interface between two immiscible fluids are\nconstructed for the case of a small viscosity ratio between the fluid phases.\nThe model is designed to explicitly account for the dependence on the contact\nangle between the two fluids and the solid surface. The Lorentz reciprocal\ntheorem is applied in the context of a geometric perturbation approach, which\nis based on the deviation of the contact angle from a 90{\\deg}-value. By\ntesting the model against experimental and numerical data from the literature,\ngood agreement is found within the entire range of contact angles below\n90{\\deg}. As an advantage of the method reported, the drag and diffusion\ncoefficients can be calculated up to second order in the perturbation\nparameter, while it is sufficient to know the velocity and pressure fields only\nup to first order. Extensions to other particle shapes with known velocity and\npressure fields are straightforward."
    },
    {
        "anchor": "Diffusion Dynamics, Moments, and Distribution of First Passage Time on\n  the Protein-Folding Energy Landscape, with Applications to Single Molecules: We study the dynamics of protein folding via statistical energy-landscape\ntheory. In particular, we concentrate on the local-connectivity case with the\nfolding progress described by the fraction of native conformations. We obtain\ninformation for the first passage-time (FPT) distribution and its moments. The\nresults show a dynamic transition temperature below which the FPT distribution\ndevelops a power-law tail, a signature of the intermittency phenomena of the\nfolding dynamics. We also discuss the possible application of the results to\nsingle-molecule dynamics experiments.",
        "positive": "Flexible helical yarn swimmers: We investigate the motion of a flexible Stokesean flagellar swimmer realised\nas a yarn made of two intertwined elastomer fibres, one active, that can\nreversibly change its length in response to a local excitation causing\ntransition to the nematic state or swelling, and the other one, a passive\nisotropic elastomer with identical mechanical properties. A propagating\nchemical wave may provide an excitation mechanism ensuring a constant length of\nthe excited region. Generally, the swimmer moves along a helical trajectory,\nand the propagation and rotation velocity are very sensitive to the ratio of\nthe excited region to the pitch of the yarn, as well as to the size of a\ncarried load. External excitation by a moving beam is less effective, unless\nthe direction of the beam is adjusted to rotation of the swimmer."
    },
    {
        "anchor": "Reconsideration on structural anisotropy of silica hydrogels prepared in\n  magnetic field: In a previous paper [A. Mori, T. Kaito, H. Furukawa, Mater. Lett. 62 (2008)\n3459-3461], we carried out birefringence measurements of Pb(II)-doped silica\nhydrogels prepared in a magnetic field (B). For a 5T sample, we observed a\nnegative birefringence with the optic axis along B. At that time, providing a\npositive intrinsic birefringence of silica, we speculated that in the\nbirefringent gels the gel network extended perpendicular to B. The purpose of\nthis paper is to reconsider this speculation on the basis of previous and\nrecent results [T. Kaito, S.-i. Yanagiya, A. Mori, M. Kurumada, C. Kaito, T.\nInoue, J. Cryst. Growth 289 (2006) 275-277; T. Kaito, A. Mori, C. Kaito, J.\nChem. Chem. Eng., 9 (2015) 61-66]. In the former, the silica gels were used as\na medium of a crystal growth of PbBr2 and aligned arrays of crystallites with\nlong axis parallel to B were obtained. In the latter, Pb(II) nanocrystallites\nwere formed in silica xerogels by electron irradiation. Both of the short axis\nof PbBr2 crystallites and the diameter of Pb(II) crystallites were a few tens\nof nanometers. This size must be a size of short axis of pores in the gel\nnetworks elongated affected by the magnetic field. Since the PbBr2 crystallites\nwere elongated along the magnetic field, we conclude that the Pb(II)-doped\nsilica gel networks aligned along the magnetic field.",
        "positive": "The role of the nucleus for cell mechanics: an elastic phase field\n  approach: The nucleus of eukaryotic cells typically makes up around 30 % of the cell\nvolume and tends to be up to ten times stiffer than the surrounding cytoplasm.\nTherefore it is an important element for cell mechanics, but a quantitative\nunderstanding of its mechanical role is largely missing. Here we demonstrate\nthat elastic phase fields can be used to describe dynamical cell processes in\nadhesive or confining environments in which the nucleus plays an important\nrole. We first introduce and verify our computational method and then study\nseveral applications of large relevance. For cells on adhesive patterns, we\nfind that nuclear stress is shielded by the adhesive pattern. For cell\ncompression between two parallel plates, we obtain force-compression curves\nthat allow us to extract an effective modulus for the cell-nucleus composite.\nFor micropipette aspiration, the effect of the nucleus on the effective modulus\nis found to be much weaker, highlighting the complicated interplay between\nextracellular geometry and cell mechanics that is captured by our approach."
    },
    {
        "anchor": "The role of interfacial friction on the peeling of thin viscoelastic\n  tapes: We study the peeling process of a thin viscoelastic tape from a rigid\nsubstrate. Two different boundary conditions are considered at the interface\nbetween the tape and the substrate: stuck adhesion, and relative sliding in the\npresence of frictional shear stress. In the case of perfectly sticking\ninterfaces, we found that the viscoelastic peeling behavior resembles the\nclassical Kendall behavior of elastic tapes, with the elastic modulus given by\nthe tape high-frequency viscoelastic modulus. Including the effect of\nfrictional sliding, which occurs at the interface adjacent to the peeling\nfront, makes the peeling behavior strongly dependent on the peeling velocity.\nAlso, at sufficiently small peeling angles, we predict a tougher peeling\nbehavior than the classical stuck cases. This phenomenon is in agreement with\nrecent experimental evidences indicating that several biological systems (e.g.\ngeckos, spiders) exploit low-angle peeling to control attachment force and\nlocomotion.",
        "positive": "Structural properties of liquids in extreme confinement: We simulate a hard-sphere liquid in confined geometry where the separation of\nthe two parallel, hard walls is smaller than two particle diameters. By\nsystematically reducing the wall separation we analyze the behavior of\nstructural and thermodynamic properties, such as inhomogeneous density\nprofiles, structure factors, and compressibilities when approaching the\ntwo-dimensional limit. In agreement with asymptotic predictions, we find for\nquasi-two-dimensional fluids that the density profile becomes parabolic and the\nstructure factor converges towards its two-dimensional counterpart. To extract\nthe compressibility in polydisperse samples a perturbative expression is used\nwhich qualitatively influences the observed non-monotonic dependence of the\ncompressibility with wall separation. We also present theoretical calculations\nbased on fundamental-measure theory and integral-equation theory, which are in\nvery good agreement with the simulation results."
    },
    {
        "anchor": "Slip, concentration fluctuations and flow instability in sheared polymer\n  solutions: Recent experiments suggest that shear-enhanced growth of concentration\nfluctuations in polymer solutions is strongly influenced by solid boundaries.\nWe analyze the dynamics of a model of a sheared polymer solution, accounting\nfor the effect of stress variations on mass flux and for wall-slip. If (and\nonly if) these effects are present, the flow exhibits a boundary-localized\ninstability consistent with experimental observations. Even in the absence of\nflow instability, thermally-driven concentration fluctuations are significantly\nenhanced near the boundary.",
        "positive": "On-the-fly coarse-graining methodology for the simulation of chain\n  formation of superparamagnetic colloids in strong magnetic fields: The aim of this work is the description of the chain formation phenomena\nobserved in colloidal suspensions of superparamagnetic nanoparticles under high\nmagnetic fields. We propose a new methodology based on an on-the-fly\nCoarse-Grain (CG) model. Within this approach, the coarse grain objects of the\nsimulation are not fixed a priori at the beginning of the simulation but rather\nredefined on the fly. The motion of the CG objects (single particles or\naggregates) is described by an anisotropic diffusion model and the magnetic\ndipole-dipole interaction is replaced by an effective short range interaction\nbetween CG objects. The new methodology correctly reproduces previous results\nfrom detailed Langevin Dynamics simulations of dispersions of superparamagnetic\ncolloids under strong fields whilst requiring an amount of CPU time orders of\nmagnitude smaller. This substantial improvement in the computational\nrequirements allows the simulation of problems in which the relevant phenomena\nextends to time scales inaccessible with previous simulation techniques. A\nrelevant example is the waiting time dependence of the relaxation time T_2 of\nwater protons observed in Magnetic Resonance experiments containing dispersions\nof superparamagnetic colloids, which is correctly predicted by our simulations.\nFuture applications may include other popular real-world applications of\nsuperparamagnetic colloids such as the magnetophoretic separation processes."
    },
    {
        "anchor": "Run-and-tumble bacteria slowly approaching the diffusive regime: The run-and-tumble (RT) dynamics followed by bacterial swimmers gives rise\nfirst to a ballistic motion due to their persistence, and later, through\nconsecutive tumbles, to a diffusive process. Here we investigate how long it\ntakes for a dilute swimmer suspension to reach the diffusive regime as well as\nwhat is the amplitude of the deviations from the diffusive dynamics. A linear\ntime dependence of the mean-squared displacement (MSD) is insufficient to\ncharacterize diffusion and thus we also focus on the excess kurtosis of the\ndisplacement distribution. Four swimming strategies are considered: (i) the\nconventional RT model with complete reorientation after tumbling, (ii) the case\nof partial reorientation, characterized by a distribution of tumbling angles,\n(iii) a run-and-reverse model with rotational diffusion, and (iv) a RT particle\nwhere the tumbling rate depends on the stochastic concentration of an internal\nprotein. By analyzing the associated kinetic equations for the probability\ndensity function and simulating the models, we find that for models (ii),\n(iii), and (iv) the relaxation to diffusion can take much longer than the mean\ntime between tumble events, evidencing the existence of large tails in the\nparticle displacements. Moreover, the excess kurtosis can assume large positive\nvalues. In model (ii) it is possible for some distributions of tumbling angles\nthat the MSD reaches a linear time dependence but, still, the dynamics remains\nnon-Gaussian for long times. This is also the case in model (iii) for small\nrotational diffusivity. For all models, the long-time diffusion coefficients\nare also obtained. The theoretical approach, which relies on eigenvalue and\nangular Fourier expansions of the van Hove function, is in excellent agreement\nwith the simulations.",
        "positive": "Random loose packing and an order parameter for the parking lot model: We have obtained the random loose packing fraction of the parking lot model\n(PLM) by taking the limit of infinite compactivity in the two-variable\nstatistical description of Tarjus and Viot for the PLM. The PLM is a stochastic\nmodel of adsorption and desorption of particles on a substrate that have been\nused as a model for compaction of granular materials. An order parameter $\\rho$\nis introduced to characterize how far from a steady state situation the model\nis. Thus, configurations with $\\rho<1$ age. We propose that $\\rho$ can be a\nstarting point in order to stablish a connection between Edwards' statistical\nmechanics and granular hydrodynamics."
    },
    {
        "anchor": "Complex Fluids: The Physics of Emulsions: These lectures start with the mean field theory for a symmetric binary fluid\nmixture, addressing interfacial tension, the stress tensor, and the equations\nof motion (Model H). We then consider the phase separation kinetics of such a\nmixture: coalescence, Ostwald ripening, its prevention by trapped species,\ncoarsening of bicontinuous states, and the role of shear flow. The third topic\naddressed is the stabilization of emulsions by using surfactants to reduce or\neven eliminate the interfacial tension between phases; the physics of bending\nenergy, which becomes relevant in the latter case, is then presented briefly.\nThe final topic is the creation of long-lived metastable emulsions by\nadsorption of colloidal particles or nano-particles at the fluid-fluid\ninterface; alongside spherical droplets, these methods can be used to create a\nrange of unconventional structures with potentially interesting properties that\nare only now being explored.",
        "positive": "Switching the structural force in ionic liquid-solvent mixtures by\n  varying composition: The structure and interactions in electrolytes at high concentration have\nimplications from energy storage to biomolecular interactions. However many\nexperimental observations are yet to be explained in these mixtures, which are\nfar beyond the regime of validity of mean field models. Here, we study the\nstructural forces in a mixture of ionic liquid and solvent that is miscible in\nall proportions at room temperature. Using the surface force balance to measure\nthe force between macroscopic smooth surfaces across the liquid mixtures, we\nuncover an abrupt increase in the wavelength above a threshold ion\nconcentration. Below the threshold concentration the wavelength is determined\nby the size of the solvent molecule, whereas above the threshold it is the\ndiameter of a cation-anion pair that determines the wavelength."
    },
    {
        "anchor": "Complex pathways and memory in compressed corrugated sheets: The nonlinear response of driven complex materials -- disordered magnets,\namorphous media, crumpled sheets -- features intricate transition pathways\nwhere the system repeatedly hops between metastable states. % which encode\nmemory effects. Such pathways encode memory effects and may allow information\nprocessing -- yet tools are lacking to experimentally observe and control these\npathways, and their full breadth has not been explored. Here we introduce\ncompression of corrugated elastic sheets to precisely observe and manipulate\n{their full}, multi-step pathways, which are reproducible, robust,and\ncontrolled by geometry. We show how manipulation of the boundaries allows to\nelicit multiple targeted pathways from a single sample. In all cases, each\nstate in the pathway can be encoded by the binary state of material 'bits'\ncalled hysterons, and the strength of their interactions plays a crucial role.\nIn particular, as function of increasing interaction strength, we observe\nPreisach pathways, expected in systems of independently switching hysterons,\n'scrambled' pathways that evidence hitherto unexplored interactions between\nthese material bits, and 'accumulator' pathways which leverage these\ninteractions to perform an elementary computation. Our work opens a route to\nprobe, manipulate and understand complex pathways, impacting future\napplications in soft robotics and information processing in materials.",
        "positive": "On the Estimation of Parameters from Time Traces originating from an\n  Ornstein-Uhlenbeck Process: In this article, we develop a Bayesian approach to estimate parameters from\ntime traces that originate from an overdamped Brownian particle in a harmonic\npotential, or Ornstein-Uhlenbeck process (OU). We show that least-square\nfitting the autocorrelation function, which is often the standard way of\nanalyzing such data, is significantly underestimating the confidence intervals\nof the fitted parameters. Here, we develop a rigorous maximum likelihood theory\nthat properly captures the underlying statistics. From the analytic solution,\nwe found that there exists an optimal measurement spacing ($\\Delta t = 0.7968\n\\tau$) that maximizes the statistical accuracy of the estimate for the\ndecay-time $\\tau$ of the process for a fixed number of samples $N$, which plays\na similar role than the Nyquist-Shannon theorem for the OU-process. In summary,\nour results have strong implications for parameter estimation for processes\nthat result in a single exponential decay in the autocorrelation function. Our\nanalysis can directly be applied to single-component dynamic light scattering\nexperiments or optical trap calibration experiments."
    },
    {
        "anchor": "Enhanced shear separation for chiral magnetic colloidal aggregates: We study the designing principles of the simplest colloidal propeller, an\narchitecture built from four identical spheres that can couple translation with\nrotation to produce controlled drift motion. By considering superparamagnetic\nbeads, we show that the simultaneous action of a magnetic field and a shear\nflow leads to the migration of the cluster in the vorticity direction. We\ninvestigate the dependence of the migration velocity on the geometrical\nparameters of the cluster, and find that significant cluster separation can be\nachieved under the typical operation conditions of microfluidic devices.",
        "positive": "Bose-Einstein condensation at constant temperature: We present a novel experimental approach to Bose-Einstein condensation by\nincreasing the particle number of the system at almost constant temperature. In\nparticular the emergence of a new condensate is observed in multi-component F=1\nspinor condensates of 87-Rb. Furthermore we develop a simple rate-equation\nmodel for multi-component BEC thermodynamics at finite temperature which well\nreproduces the measured effects."
    },
    {
        "anchor": "Electric double layer of anisotropic dielectric colloids under electric\n  fields: Anisotropic colloidal particles constitute an important class of building\nblocks for self-assembly directed by electrical fields. The aggregation of\nthese building blocks is driven by induced dipole moments, which arise from an\ninterplay between dielectric effects and the electric double layer. For\nparticles that are anisotropic in shape, charge distribution, and dielectric\nproperties, calculation of the electric double layer requires coupling of the\nionic dynamics to a Poisson solver. We apply recently proposed methods to solve\nthis problem for experimentally employed colloids in static and time-dependent\nelectric fields. This allows us to predict the effects of field strength and\nfrequency on the colloidal properties.",
        "positive": "Cell shape analysis of random tessellations based on Minkowski tensors: To which degree are shape indices of individual cells of a tessellation\ncharacteristic for the stochastic process that generates them? Within the\ncontext of stochastic geometry and the physics of disordered materials, this\ncorresponds to the question of relationships between different stochastic\nmodels. In the context of image analysis of synthetic and biological materials,\nthis question is central to the problem of inferring information about\nformation processes from spatial measurements of resulting random structures.\nWe address this question by a theory-based simulation study of shape indices\nderived from Minkowski tensors for a variety of tessellation models. We focus\non the relationship between two indices: an isoperimetric ratio of the\nempirical averages of cell volume and area and the cell elongation quantified\nby eigenvalue ratios of interfacial Minkowski tensors. Simulation data for\nthese quantities, as well as for distributions thereof and for correlations of\ncell shape and volume, are presented for Voronoi mosaics of the Poisson point\nprocess, determinantal and permanental point processes, and Gibbs hard-core and\nrandom sequential absorption processes as well as for Laguerre tessellations of\npolydisperse spheres and STIT- and Poisson hyperplane tessellations. These data\nare complemented by mechanically stable crystalline sphere and disordered\nellipsoid packings and area-minimising foam models. We find that shape indices\nof individual cells are not sufficient to unambiguously identify the generating\nprocess even amongst this limited set of processes. However, we identify\nsignificant differences of the shape indices between many of these tessellation\nmodels. Given a realization of a tessellation, these shape indices can narrow\nthe choice of possible generating processes, providing a powerful tool which\ncan be further strengthened by density-resolved volume-shape correlations."
    },
    {
        "anchor": "Theory of wetting-induced fluid entrainment by advancing contact lines\n  on dry surfaces: We report on the onset of fluid entrainment when a contact line is forced to\nadvance over a dry solid of arbitrary wettability. We show that entrainment\noccurs at a critical advancing speed beyond which the balance between\ncapillary, viscous and contact line forces sustaining the shape of the\ninterface is no longer satisfied. Wetting couples to the hydrodynamics by\nsetting both the morphology of the interface at small scales and the viscous\nfriction of the front. We find that the critical deformation that the interface\ncan sustain is controlled by the friction at the contact line and the viscosity\ncontrast between the displacing and displaced fluids, leading to a rich variety\nof wetting-entrainment regimes. We discuss the potential use of our theory to\nmeasure contact-line forces using atomic force microscopy, and to study\nentrainment under microfluidic conditions exploiting colloid-polymer fluids of\nultra-low surface tension.",
        "positive": "Rheology of confined non-Brownian suspensions: We study the rheology of confined suspensions of neutrally buoyant rigid\nmonodisperse spheres in plane-Couette flow using Direct Numerical Simulations.\nWe find that if the width of the channel is a (small) integer multiple of the\nsphere's diameter, the spheres self-organize into two-dimensional layers that\nslide on each other and the suspension's effective viscosity is significantly\nreduced. Each two-dimensional layer is found to be structurally liquid-like but\ntheir dynamics is frozen in time."
    },
    {
        "anchor": "Aggregation of superparamagnetic colloids in magnetic fields: the quest\n  for the equilibrium state: Experimental and simulation studies of superparamagnetic colloids in strong\nexternal fields have systematically shown an irreversible aggregation process\nin which chains of particles steadily grow and the average size increases with\ntime as a power-law. Here we show, by employing Langevin dynamics simulations\nthe existence of a different aggregation behavior: aggregates form during a\ntransient period and the system attains an equilibrium distribution of\naggregate sizes. A thermodynamic self-assembly theory supports the simulation\nresults and it also predicts that the average aggregate size in the equilibrium\nstate depends only on a dimensionless parameter combining the volume fraction\nof colloids phi0 and the magnetic coupling parameter Gamma. The conditions\nunder which this new behavior can be observed are discussed.",
        "positive": "Cusp-shaped Elastic Creases and Furrows: The surfaces of growing biological tissues, swelling gels, and compressed\nrubbers do not remain smooth, but frequently exhibit highly localized inward\nfolds. We reveal the morphology of this surface folding in a novel experimental\nsetup, which permits to deform the surface of a soft gel in a controlled\nfashion. The interface first forms a sharp furrow, whose tip size decreases\nrapidly with deformation. Above a critical deformation, the furrow bifurcates\nto an inward folded crease of vanishing tip size. We show experimentally and\nnumerically that both creases and furrows exhibit a universal cusp-shape, whose\nwidth scales like $y^{3/2}$ at a distance $y$ from the tip. We provide a\nsimilarity theory that captures the singular profiles before and after the\nself-folding bifurcation, and derive the length of the fold from large\ndeformation elasticity."
    },
    {
        "anchor": "Capillary-bridge Forces Between Solid Particles: Insights from Lattice\n  Boltzmann Simulations: Liquid capillary-bridge formation between solid particles has a critical\ninfluence on the rheological properties of granular materials and, in\nparticular, on the efficiency of fluidized bed reactors. The available\nanalytical and semi-analytical methods have inherent limitations, and often do\nnot cover important aspects, like the presence of non-axisymmetric bridges.\nHere, we conduct numerical simulations of the capillary bridge formation\nbetween equally and unequally-sized solid particles using the lattice Boltzmann\nmethod, and provide an assessment of the accuracy of different families of\nanalytical models. We find that some of the models taken into account are shown\nto perform better than others. However, all of them fail to predict the\ncapillary force for contact angles larger than $\\pi/2$, where a repulsive\ncapillary force attempts to push the solid particle outwards to minimize the\nsurface energy, especially at a small separation distance.",
        "positive": "Wall effects on granular heap stability: We investigate the effects of lateral walls on the angle of movement and on\nthe angle of repose of a granular pile. Our experimental results for beads\nimmersed in water are similar to previous results obtained in air and to recent\nnumerical simulations. All of these results, showing an increase of pile angles\nwith a decreasing gap width, are explained by a model based on the redirection\nof stresses through the granular media. Two regimes are observed depending on\nthe bead diameter. For large beads, the range of wall effects corresponds to a\nconstant number of beads whereas it corresponds to a constant characteristic\nlength for small beads as they aggregate via van der Waals forces."
    },
    {
        "anchor": "El Fenomeno de Maduracion de Ostwald. Predicciones de las Simulaciones\n  de Estabilidad de Emulsiones sobre la Evolucion del Radio Cubico Promedio de\n  una Dispersion de Aceite en Agua: In this chapter, the theory of Lifshitz, Slesov and Wagner and the technique\nof Emulsion Stability Simulations (ESS) are reviewed. Complementary algorithms\nrequired to incorporate the phenomenon of Ostwald ripening in ESS are\npresented. The simulations are used to study the behavior of dodecane-in-water\nnanoemulsions as a function of time. The influence of electrostatic\ninteractions, hydration forces, the initial drop size distributions, and the\ndeformability of the drops, are studied. In particular, the behavior of the\ncube average radius of the dispersion and the variation of the drop size\ndistribution a few minutes after the preparation of the emulsion are described.",
        "positive": "Macroscopic model with anisotropy based on micro-macro informations: Physical experiments can characterize the elastic response of granular\nmaterials in terms of macroscopic state-variables, namely volume (packing)\nfraction and stress, while the microstructure is not accessible and thus\nneglected. Here, by means of numerical simulations, we analyze dense,\nfrictionless, granular assemblies with the final goal to relate the elastic\nmoduli to the fabric state, i.e., to micro-structural averaged contact network\nfeatures as contact number density and anisotropy.\n  The particle samples are first isotropically compressed and later\nquasi-statically sheared under constant volume (undrained conditions). From\nvarious static, relaxed configurations at different shear strains, now\ninfinitesimal strain steps are applied to \"measure\" the effective elastic\nresponse; we quantify the strain needed so that plasticity in the sample\ndevelops as soon as contact and structure rearrangements happen. Because of the\nanisotropy induced by shear, volumetric and deviatoric stresses and strains are\ncross-coupled via a single anisotropy modulus, which is proportional to the\nproduct of deviatoric fabric and bulk modulus (i.e. the isotropic fabric).\nInterestingly, the shear modulus of the material depends also on the actual\nstress state, along with the contact configuration anisotropy.\n  Finally, a constitutive model based on incremental evolution equations for\nstress and fabric is introduced. By using the previously measured dependence of\nthe stiffness tensor (elastic moduli) on the microstructure, the theory is able\nto predict with good agreement the evolution of pressure, shear stress and\ndeviatoric fabric (anisotropy) for an independent undrained cyclic shear test,\nincluding the response to reversal of strain."
    },
    {
        "anchor": "Identifying polymer states by machine learning: The ability of a feed-forward neural network to learn and classify different\nstates of polymer configurations is systematically explored. Performing\nnumerical experiments, we find that a simple network model can, after adequate\ntraining, recognize multiple structures, including gas-like coil, liquid-like\nglobular, and crystalline anti-Mackay and Mackay structures. The network can be\ntrained to identify the transition points between various states, which compare\nwell with those identified by independent specific-heat calculations. Our study\ndemonstrates that neural network provides an unconventional tool to study the\nphase transitions in polymeric systems.",
        "positive": "Compaction of Quasi One-Dimensional Elastoplastic Materials: Insight in the crumpling or compaction of one-dimensional objects is of great\nimportance for understanding biopolymer packaging and designing innovative\ntechnological devices. By compacting various types of wires in rigid\nconfinements and characterizing the morphology of the resulting crumpled\nstructures, here we report how friction, plasticity, and torsion enhance\ndisorder, leading to a transition from coiled to folded morphologies. In the\nlatter case, where folding dominates the crumpling process, we find that\nreducing the relative wire thickness counter-intuitively causes the maximum\npacking density to decrease. The segment-size distribution gradually becomes\nmore asymmetric during compaction, reflecting an increase of spatial\ncorrelations. We introduce a self-avoiding random walk model and verify that\nthe cumulative injected wire length follows a universal dependence on segment\nsize, allowing for the prediction of the efficiency of compaction as a function\nof material properties, container size, and injection force."
    },
    {
        "anchor": "Langevin Dynamics simulations of a 2-dimensional colloidal crystal under\n  confinement and shear: Langevin Dynamics simulations are used to study the effect of shear on a\ntwo-dimensional colloidal crystal confined by structured parallel walls. When\nwalls are sheared very slowly, only two or three crystalline layers next to the\nwalls move along with them, while the inner layers of the crystal are only\nslightly tilted. At higher shear velocities, this inner part of the crystal\nbreaks into several pieces with different orientations. The velocity profile\nacross the slit is reminiscent of shear-banding in flowing soft materials,\nwhere liquid and solid regions coexist; the difference, however, is that in the\nlatter case the solid regions are glassy while here they are crystalline. At\neven higher shear velocities, the effect of the shearing becomes smaller again.\nAlso the effective temperature near the walls (deduced from the velocity\ndistributions of the particles) decreases again when the wall velocity gets\nvery large. When the walls are placed closer together, thereby introducing a\nmisfit, a structure containing a soliton staircase arises in simulations\nwithout shear. Introducing shear increases the disorder in these systems until\nno solitons are visible any more. Instead, similar structures like in the case\nwithout misfit result. At high shear rates, configurations where the\nincommensurability of the crystalline structure is compensated by the creation\nof holes become relevant.",
        "positive": "Finite-size Domains in a Membrane with Two-state Active Inclusions: We propose a model that leads to the formation of non-equilibrium finite-size\ndomains in a biological membrane. Our model considers the active conformational\nchange of the inclusions and the coupling between inclusion density and\nmembrane curvature. Two special cases with different interactions are studied\nby Monte Carlo simulations. In case (i) exited state inclusions prefer to\naggregate. In case (ii) ground state inclusions prefer to aggregate. When the\ninclusion density is not coupled to the local membrane curvature, in case (i)\nthe typical length scale ($\\sqrt{M}$) of the inclusion clusters shows weak\ndependence on the excitation rate ($K_{on}$) of the inclusions for a wide range\nof $K_{on}$ but increases fast when $K_{on}$ becomes sufficiently large; in\ncase (ii) $\\sqrt{M}\\sim {K_{on}}^{-{1/3}}$ for a wide range of $K_{on}$. When\nthe inclusion density is coupled to the local membrane curvature, the curvature\ncoupling provides the upper limit of the inclusion clusters. In case (i) (case\n(ii)), the formation of the inclusions is suppressed when $K_{off}$ ($K_{on}$)\nis sufficiently large such that the ground state (excited state) inclusions do\nnot have sufficient time to aggregate. We also find that the mobility of an\ninclusion in the membrane depends on inclusion-curvature coupling. Our study\nsuggests possible mechanisms that produce finite-size domains in biological\nmembranes."
    },
    {
        "anchor": "Effects of interplay of nanoparticles, surfactants and base fluid on the\n  interfacial tension of nanocolloids: A systematically designed study has been conducted to understand and clearly\ndemarcate the degree of contribution by the constituting elements to the\nsurface tension of nanocolloids. The effects of elements such as surfactants,\nparticles and the combined effects of these on the interfacial tension of these\ncomplex fluids are studied employing pendant drop shape analysis method by\nfitting Young Laplace equation. Only particle has shown considerable increase\nin surface tension with particle concentration in a polar medium like DI water\nwhereas only marginal effect particles on surface tension in weakly polar\nmediums like glycerol and ethylene glycol. Such behaviour has been attributed\nto the enhanced desorption of particles to the interface and a mathematical\nframework has been derived to quantify this. Combined particle and surfactant\neffect on surface tension of complex nanofluid system showed a decreasing\nbehaviour with respect to the particle and surfactant concentration with a\nconsiderably feeble effect of particle concentration. This combined colloidal\nsystem recorded a surface tension value below the surface tension of aqueous\nsurfactant system at the same concentration, which is a counterintuitive\nobservation as only particle results in increase in surface tension and only\nsurfactant results in decrease in surface tension. The possible physical\nmechanism behind such an anomaly happening at the complex fluid air interface\nhas been explained. Detailed analyses based on thermodynamic, mechanical and\nchemical equilibrium of the constituents and their adsorption-desorption\ncharacteristics as extracted from Gibbs adsorption analysis has been provided.",
        "positive": "The role of fluid flow in the dynamics of active nematic defects: We adapt the Halperin-Mazenko formalism to analyze two-dimensional active\nnematics coupled to a generic fluid flow. The governing hydrodynamic equations\nlead to evolution laws for nematic topological defects and their corresponding\ndensity fields. We find that $\\pm 1/2$ defects are propelled by the local fluid\nflow and by the nematic orientation coupled with the flow shear rate. In the\noverdamped and compressible limit, we recover the previously obtained active\nself-propulsion of the +1/2 defects. Non-local hydrodynamic effects are\nprimarily significant for incompressible flows, for which it is not possible to\neliminate the fluid velocity in favor of the local defect polarization alone.\nFor the case of two defects with opposite charge, the non-local hydrodynamic\ninteraction is mediated by non-reciprocal pressure-gradient forces. Finally, we\nderive continuum equations for a defect gas coupled to an arbitrary\n(compressible or incompressible) fluid flow."
    },
    {
        "anchor": "Phase behaviour and dynamics in primitive models of molecular ionic\n  liquids: The phase behaviour and dynamics of molecular ionic liquids are studied using\nprimitive models and extensive computer simulations. The models account for\nsize disparity between cation and anion, charge location on the cation, and\ncation-shape anisotropy, which are all prominent features of important\nmaterials such as room-temperature ionic liquids. The vapour-liquid phase\ndiagrams are determined using high-precision Monte Carlo simulations, setting\nthe scene for in-depth studies of ion dynamics in the liquid state. Molecular\ndynamics simulations are used to explore the structure, single-particle\ntranslational and rotational autocorrelation functions, cation orientational\nautocorrelations, self diffusion, viscosity, and frequency-dependent\nconductivity. The results reveal some of the molecular-scale mechanisms for\ncharge transport, involving molecular translation, rotation, and association.",
        "positive": "Capture on High Curvature Region: Aggregation of Colloidal Particle\n  Bound to Giant Phospholipid Vesicles: A very recent observation on the membrane mediated attraction and ordered\naggregation of colloidal particles bound to giant phospholipid vesicles (I.\nKoltover, J. O. R\\\"{a}dler, C. R. Safinya, Phys. Rev. Lett. {\\bf 82},\n1991(1999)) is investigated theoretically within the frame of Helfrich\ncurvature elasticity theory of lipid bilayer fluid membrane. Since the concave\nor waist regions of the vesicle possess the highest local bending energy\ndensity, the aggregation of colloidal beads on these places can reduce the\nelastic energy in maximum. Our calculation shows that a bead in the concave\nregion lowers its energy $\\sim 20 k_B T$. For an axisymmetrical dumbbell\nvesicle, the local curvature energy density along the waist is equally of\nmaximum, the beads can thus be distributed freely with varying separation\ndistance."
    },
    {
        "anchor": "Spin-rotation interaction in fullerite C60: We report on the 13C spin-lattice relaxation times in polycristalline\nfullerite C60 measured over the temperature range 295 K to 1000 K. At\ntemperatures above 470 K, spin-lattice relaxation is dominated by the\nspin-rotation interaction. From the analysis of temperature dependence of\nT1(13C), the spin-rotation constant is determined using J- and M-models of\nrotational diffusion: C(J)=-51 Hz, C(M)=-29 Hz.",
        "positive": "Theory and Simulation of DNA-Coated Colloids: a Guide for Rational\n  Design: By exploiting the exquisite selectivity of DNA hybridization, DNA-Coated\nColloids (DNACCs) can be made to self-assemble in a wide variety of structures.\nThe beauty of this system stems largely from its exceptional versatility and\nfrom the fact that a proper choice of the grafted DNA sequences yields fine\ncontrol over the colloidal interactions. Theory and simulations have an\nimportant role to play in the optimal design of self- assembling DNACCs. At\npresent, the powerful model-based design tools are not widely used, because the\ntheoretical literature is fragmented and the connection between different\ntheories is often not evident. In this Perspective, we aim to discuss the\nsimilarities and differences between the different models that have been\ndescribed in the literature, their underlying assumptions, their strengths and\ntheir weaknesses. Using the tools described in the present Review, it should be\npossible to move towards a more rational design of novel self-assembling\nstructures of DNACCs and, more generally, of systems where ligand-receptors\nbonds are used to control interactions."
    },
    {
        "anchor": "Freezing-induced topological transition of double-emulsion: Solidification of complex liquids is pertinent to numerous natural and\nindustrial processes. Here, we examine the freezing of a W/O/W double-emulsion,\ni.e., water-in-oil compound droplets dispersed in water. We show that the\nsolidification of such hierarchical emulsions can trigger a topological\ntransition; for example, in our case, we observe the transition from the stable\nW/O/W state to a (frozen) O/W single-emulsion configuration. Strikingly, this\ntransition is characterised by sudden expulsion of the inner water drop from\nthe encapsulating oil droplet. We propose that this topological transition is\ntriggered by the freezing of the encapsulating oil droplet from the outside in,\nputting tension on the inner water drop thus, destabilizing the W/O/W\nconfiguration. Using high-speed imaging we characterize the destabilization\nprocess. Interestingly, we find that below a critical size of the inner drop,\n$R_{\\mathrm{in,crit}} \\approx 19 \\, \\mu\\mathrm{m}$, the topological transition\ndoes not occur any more and the double-emulsion remains stable, in line with\nour interpretation.",
        "positive": "In-plane structure of the electric double layer in the primitive model\n  using classical density functional theory: The electric double layer (EDL) has a pivotal role in screening charges on\nsurfaces as in supercapacitor electrodes or colloidal and polymer solutions.\nIts structure is determined by correlations between the finite-sized ionic\ncharge carriers of the underlying electrolyte and, this way, these correlations\naffect the properties of the EDL and of applications utilizing EDLs. We study\nthe structure of EDLs within classical density functional theory (DFT) in order\nto uncover whether a structural transition in the first layer of the EDL that\nis driven by changes in the surface potential depends on specific particle\ninteractions or has a general footing. This transition has been found in\nfull-atom simulations. Thus far, investigating the in-plane structure of the\nEDL for the primitive model (PM) using DFT proved a challenge. We show here\nthat the use of an appropriate functional predicts the in-plane structure of\nEDLs in excellent agreement with molecular dynamics (MD) simulations. This\nprovides the playground to investigate how the structure factor within a layer\nparallel to a charged surface changes as function of both the applied surface\npotential and its separation from the surface. We discuss pitfalls in properly\ndefining an in-plane structure factor and fully map out the structure of the\nEDL within the PM for a wide range of electrostatic electrode potentials.\nHowever, we do not find any signature of a structural crossover and conclude\nthat the previously reported effect is not fundamental but rather occurs due to\nthe specific force field of ions used in the simulations."
    },
    {
        "anchor": "Minkowski functionals for phase behavior under confinement: In this work, the Minkowski functionals are used as a framework to study how\nmorphology (i.e. the shape of a structure) and topology (i.e. how different\nstructures are connected) influence wall adsorption and capillary condensation\nunder tight confinement. Numerical simulations based on classical density\nfunctional theory (DFT) are run for a wide variety of geometries using both\nhard-sphere and Lennard-Jones fluids. These DFT computations are compared to\nresults obtained using the Minkowski functionals. It is found that the\nMinkowski functionals can provide a good description of the behavior of\nLennard-Jones fluids down to small system sizes. In addition, through\ndecomposition of the free energy, the Minkowski functionals provide a good\nframework to better understand what are the dominant contributions to the\nphysics of a system. Lastly, while studying the phase envelope shift as a\nfunction of the Minkowski functionals it is found that topology has a different\neffect depending on whether the phase transition under consideration is a\nfirst- or a second-order transition.",
        "positive": "Breakdown of Nonlinear Elasticity in Stress-Controlled Thermal Amorphous\n  Solids: In recent work it was clarified that amorphous solids under strain control do\nnot possess nonlinear elastic theory in the sense that the shear modulus exists\nbut nonlinear moduli exhibit sample to sample fluctuations that grow without\nbound with the system size. More relevant however for experiments are the\nconditions of stress control. In the present Communication we show that also\nunder stress control the shear modulus exists but higher order moduli show\nunbounded sample to sample fluctuation. The unavoidable consequence is that the\ncharacterization of stress-strain curves in experiments should be done with a\nstress-dependent shear modulus rather than with nonlinear expansions."
    },
    {
        "anchor": "The glass transition of two-dimensional binary soft disk mixtures with\n  large size ratios: We simulate binary soft disk systems in two dimensions, and investigate how\nthe dynamics slow as the area fraction is increased toward the glass\ntransition. The \"fragility\" quantifies how sensitively the relaxation time\nscale depends on the area fraction, and the fragility strongly depends on the\ncomposition of the mixture. We confirm prior results for mixtures of particles\nwith similar sizes, where the ability to form small crystalline regions\ncorrelates with fragility. However, for mixtures with particle size ratios\nabove 1.4, we find that the fragility is not correlated with structural\nordering, but rather with the spatial distribution of large particles. The\nlarge particles have slower motion than the small particles, and act as\nconfining \"walls\" which slow the motion of nearby small particles. The\nrearrangement of these confining structures governs the lifetime of dynamical\nheterogeneity, that is, how long local regions exhibit anomalously fast or slow\nbehavior. The strength of the confinement effect is correlated with the\nfragility and also influences the aging behavior of glassy systems.",
        "positive": "Simulation and observation of line-slip structures in columnar\n  structures of soft spheres: We present the computed phase diagram of columnar structures of soft spheres\nunder pressure, of which the main feature is the appearance and disappearance\nof line slips, the shearing of adjacent spirals, as pressure is increased. A\ncomparable experimental observation is made on a column of bubbles under forced\ndrainage, clearly exhibiting the expected line slip."
    },
    {
        "anchor": "Stable Oxide Nanoparticle Clusters Obtained by Complexation: We report on the electrostatic complexation between polyelectrolyte-neutral\ncopolymers and oppositely charged 6 nm-crystalline nanoparticles. For two\ndifferent dispersions of oxide nanoparticles, the electrostatic complexation\ngives rise to the formation of stable nanoparticle clusters in the range 20 -\n100 nm. It is found that inside the clusters, the particles are pasted together\nby the polyelectrolyte blocks adsorbed on their surface. Cryo-transmission\nelectronic microscopy allows to visualize the clusters and to determine the\nprobability distributions functions in size and in aggregation number. The\ncomparison between light scattering and cryo-microscopy results suggests the\nexistence of a polymer brush around the clusters.",
        "positive": "Divergence of Voronoi cell anisotropy vector: A threshold-free\n  characterization of local structure in amorphous materials: Characterizing structural inhomogeneity is an essential step in understanding\nthe mechanical response of amorphous materials. We introduce a threshold-free\nmeasure based on the field of vectors pointing from the center of each particle\nto the centroid of the Voronoi cell in which the particle resides. These\nvectors tend to point in toward regions of high free volume and away from\nregions of low free volume, reminiscent of sinks and sources in a vector field.\nWe compute the local divergence of these vectors, for which positive values\ncorrespond to overpacked regions and negative values identify underpacked\nregions within the material. Distributions of this divergence are nearly\nGaussian with zero mean, allowing for structural characterization using only\nthe moments of the distribution. We explore how the standard deviation and\nskewness vary with packing fraction for simulations of bidisperse systems and\nfind a kink in these moments that coincides with the jamming transition."
    },
    {
        "anchor": "Elasticity in the Gauge Theory of Active Nematics with Topological\n  Defects: We analyze the phase behavior of lyotropic nematic liquid crystals in the\nself-organizing flow, viz. so called active nematics (AN). Their elastic\nproperties are mutually caused by evolution of topological defects (for\ninstance, disclinations and boojums) and the flow regime. Such changes in\nelasticity of AN comparing with conventional inactive ones set the new working\ncharacteristics of these materials, have an influence on their switchable and\ntunable properties. In this work, we study the uniaxial droplet AN phases with\ntopological defects in their collective flow, we apply the gauge string-like\ntheory using the method of differential forms on a lattice interchanging the\ndrive-force concept. The results of our numerical modeling with Monte Carlo\nmethod show, that under certain conditions, the type of the phase transition\nfrom nematic to isotropic (N-I) phase and the thermodynamical characteristics\nin an active regime may differ from such one in the conventional lyotropic\nnematcis.",
        "positive": "Effect of external tension on the wetting of an elastic sheet: Recent studies of elasto-capillary phenomena have triggered interest in a\nbasic variant of the classical Young-Laplace-Dupr\\'e (YLD) problem: The\ncapillary interaction between a liquid drop and a thin solid sheet of low\nbending stiffness. Here, we consider a two-dimensional model where the sheet is\nsubjected to an external tensile load and the drop is characterized by a\nwell-defined Young's contact angle $\\theta_Y$. Using a combination of\nnumerical, variational, and asymptotic techniques, we discuss wetting as a\nfunction of the applied tension. We find that, for wettable surfaces with\n$0<\\theta_Y<\\pi/2$, complete wetting is possible below a critical applied\ntension thanks to the deformation of the sheet in contrast with rigid\nsubstrates requiring $\\theta_Y=0$. Conversely, for very large applied tensions,\nthe sheet becomes flat and the classical YLD situation of partial wetting is\nrecovered. At intermediate tensions, a vesicle forms in the sheet, which\nencloses most of the fluid and we provide an accurate asymptotic description of\nthis wetting state in the limit of small bending stiffness. We show that\nbending stiffness, however small, affects the entire shape of the vesicle. Rich\nbifurcation diagrams involving partial wetting and ``vesicle'' solution are\nfound. For moderately small bending stiffnesses, partial wetting can coexist\nboth with the vesicle solution and complete wetting. Finally, we identify a\ntension-dependent bendo-capillary length, $\\lambda_\\text{BC}$, and find that\nthe shape of the drop is determined by the ratio $A/\\lambda_\\text{BC}^2$, where\n$A$ is the area of the drop."
    },
    {
        "anchor": "There and back again: bridging meso- and nanoscales to understand lipid\n  vesicle patterning: We describe a complete methodology to bridge the scales between nanoscale\nMolecular Dynamics and (micrometer) mesoscale Monte Carlo simulations in lipid\nmembranes and vesicles undergoing phase separation, in which curving molecular\nspecies are furthermore embedded. To go from the molecular to the mesoscale, we\nnotably appeal to physical renormalization arguments enabling us to rigorously\ninfer the mesoscale interaction parameters from its molecular counterpart. We\nalso explain how to deal with the physical timescales at stake at the\nmesoscale. Simulating the so-obtained mesoscale system enables us to\nequilibrate the long wavelengths of the vesicles of interest, up to the vesicle\nsize. Conversely, we then backmap from the meso- to the nano- scale, which\nenables us to equilibrate in turn the short wavelengths down to the molecular\nlength-scales. By applying our approach to the specific situation of the\npatterning of a vesicle membrane, we show that macroscopic membranes can thus\nbe equilibrated at all length-scales in achievable computational time offering\nan original strategy to address the fundamental challenge of time scale in\nsimulations of large bio-membrane systems.",
        "positive": "Hydrodynamics determines collective motion and phase behavior of active\n  colloids: We study the collective motion of confined spherical microswimmers such as\nactive colloids which we model by so-called squirmers. To simulate hydrodynamic\nflow fields including thermal noise, we use the method of multi-particle\ncollision dynamics. We demonstrate that hydrodynamic near fields acting between\nsquirmers as well as squirmers and bounding walls crucially determine their\ncollective motion. In particular, with increasing density we observe a clear\nphase separation into a gas-like and cluster phase for neutral squirmers\nwhereas strong pushers and pullers more gradually approach the hexagonal\ncluster state."
    },
    {
        "anchor": "Explainability and Transferability of Machine Learning Models for\n  Predicting the Glass Transition Temperature of Polymers: Machine learning offers promising tools to develop surrogate models for\npolymer structure-property relations. Surrogate models can be built upon\nexisting polymer data and are useful for rapidly predicting the properties of\nunknown polymers. The accuracy of such ML models appears to depend on the\nfeature space representation of polymers, the range of training data, and\nlearning algorithms. Here, we establish connections between these factors for\npredicting the glass transition temperature of polymers. Our analysis suggests\nlinear models with a smaller number of fitting parameters are as accurate as\nnonlinear models with a large number of hidden and unexplainable parameters.\nAlso, the performance of a monomer topology-based ML model is found to be\nqualitatively identical to that of a physicochemical descriptor-based ML model.\nWe find that the transferability of ML models enhances as the property range of\nthe training data increases. Moreover, we establish new Tg polymer chemistry\ncorrelations via ML. Our work illustrates how ML can advance the fundamental\nunderstanding of polymer structure-property correlations.",
        "positive": "Experimental Demonstration of Coupled Learning in Elastic Networks: Coupled learning is a contrastive scheme for tuning the properties of\nindividual elements within a network in order to achieve desired functionality\nof the system. It takes advantage of physics both to learn using local rules\nand to \"compute\" the output response to input data, thus enabling the system to\nperform decentralized computation without the need for a processor or external\nmemory. We demonstrate a proof-of-concept mechanical network that can learn\nsimple tasks such as self-symmetrizing via iterative tuning of individual\nspring rest lengths. These mechanical networks could feasibly be scaled and\nautomated to solve increasingly complex tasks, hinting at a new class of\n\"smart\" metamaterials."
    },
    {
        "anchor": "Self-assembly of DNA-coded nanoclusters: We present a theoretical discussion of a self-assembly scheme which makes it\npossible to use DNA to uniquely encode the composition and structure of micro-\nand nanoparticle clusters. These anisotropic DNA-decorated clusters can be\nfurther used as building blocks for hierarchical self-assembly of larger\nstructures. We address several important aspects of possible experimental\nimplementation of the proposed scheme: the competition between different types\nof clusters in a solution, possible jamming in an unwanted configuration, and\nthe degeneracy due to symmetry with respect to particle permutations.",
        "positive": "Modulated 3D cross-correlation light scattering: improving turbid sample\n  characterization: Accurate characterization using static light scattering (SLS) and dynamic\nlight scattering (DLS) methods mandates the measurement and analysis of\nsingly-scattered light. In turbid samples, the suppression of multiple\nscattering is therefore required to obtain meaningful results. One powerful\ntechnique for achieving this, known as 3D cross-correlation, uses two\nsimultaneous light scattering experiments performed at the same scattering\nvector on the same sample volume in order to extract only the single scattering\ninformation common to both. Here we present a significant improvement to this\nmethod in which the two scattering experiments are temporally separated by\nmodulating the incident laser beams and gating the detector outputs at\nfrequencies exceeding the timescale of the system dynamics. This robust\nmodulation scheme eliminates cross-talk between the two beam- detector pairs\nand leads to a four-fold improvement in the cross-correlation intercept. We\nmeasure the dynamic and angular-dependent scattering intensity of turbid\ncolloidal suspensions and exploit the improved signal quality of the modulated\n3D cross-correlation DLS and SLS techniques."
    },
    {
        "anchor": "Diffusion Fails to Make a Stink: In this work we consider the question of whether a simple diffusive model can\nexplain the scent tracking behaviours found in nature. For this behaviour to\noccur, both the concentration of a scent and its gradient must be above some\nthreshold. Applying these conditions to the solutions of various diffusion\nequations, we find that a purely diffusive model cannot simultaneously satisfy\nthe tracking conditions when parameters are in the experimentally observed\nrange. This demonstrates the necessity of modelling odor dispersal with full\nfluid dynamics, where non-linear phenomena such as turbulence play a critical\nrole.",
        "positive": "Formation of molecules near a Feshbach resonance in a 1D optical lattice: We calculate the binding energy of two atoms interacting near a Feshbach\nresonance in the presence of a 1D periodic potential. The critical value of the\nscattering length needed to produce a molecule as well as the value of the\nmolecular binding energy in the unitarity limit of infinite scattering length\nare calculated as a function of the intensity of the laser field generating the\nperiodic potential. The Bloch bandwidth and the effective mass of molecules are\nshown to depend strongly on the value of the scattering length due to the\ncorrelated motion of the two atoms."
    },
    {
        "anchor": "Diffusion limited reactions in confined environments: We study the effect of confinement on diffusion limited bimolecular reactions\nwithin a lattice model where a small number of reactants diffuse amongst a much\nlarger number of inert particles. When the number of inert particles is held\nconstant the rate of the reaction is slow for small reaction volumes due to\nlimited mobility from crowding, and for large reaction volumes due to the\nreduced concentration of the reactants. The reaction rate proceeds fastest at\nan intermediate confinement corresponding to volume fraction near 1/2 and 1/3\nin two and three dimensions, respectively. We generalize the model to\noff-lattice systems with hydrodynamic coupling and predict that the optimal\nreaction rate for monodisperse colloidal systems occurs when the volume\nfraction is ~0.18. Finally, we discuss the application of our model to\nbimolecular reactions inside cells as well as the dynamics of confined\npolymers.",
        "positive": "Instantaneous normal modes of glass-forming liquids during the athermal\n  relaxation process of the steepest descent algorithm: Understanding glass formation by quenching remains a challenge in soft\ncondensed matter physics. Recent numerical studies on steepest descent\ndynamics, which is one of the simplest models of quenching, revealed that\nquenched liquids undergo slow relaxation with a power law towards mechanical\nequilibrium and that the late stage of this process is governed by local\nrearrangements of particles. These advances motivate the detailed study of\ninstantaneous normal modes during the relaxation process because the glassy\ndynamics is considered to be governed by stationary points of the potential\nenergy landscape. Here, we performed a normal mode analysis of configurations\nduring the steepest descent dynamics and found that the dynamics is driven by\nalmost flat directions of the potential energy landscape at long times. These\ndirections correspond to localized modes and we characterized them in terms of\ntheir statistics and structure using methods developed in the study of local\nminima of the potential energy landscape."
    },
    {
        "anchor": "Drag acting on an intruder in a three-dimensional granular environment: The drag acting on an intruder in a three-dimensional frictionless dry\ngranular environment is numerically studied. It is found the followings: (i)\nThere is no yield force for the motion of the intruder without the gravity.\n(ii) The drag is proportional to the cross section of the moving intruder.\n(iii) If the intruder is larger than surrounding grains, the drag is\nproportional to the moving speed $V$ of the intruder for dense systems, but it\nexhibits a crossover from quadratic to linear dependences of the moving speed\nwhen the volume fraction of the surrounding grains is much lower than the\njamming point. (iv) There is a plateau regime where the drag is almost\nindependent of $V$ if the size of the intruder is identical to those of the\nenvironmental grains and the volume fraction is near the jamming point.",
        "positive": "Extent of force indeterminacy in packings of frictional rigid disks: Static packings of frictional rigid particles are investigated by means of\ndiscrete element simulations. We explore the ensemble of allowed force\nrealizations in the space of contact forces for a given packing structure. We\nestimate the extent of force indeterminacy with different methods. The\nindeterminacy exhibits a nonmonotonic dependence on the interparticle friction\ncoefficient. We verify directly that larger force-indeterminacy is accompanied\nby a more robust behavior against local perturbations. We also investigate the\nlocal indeterminacy of individual contact forces. The probability distribution\nof local indeterminacy changes its shape depending on friction. We find that\nlocal indeterminacy tends to be larger on force chains for intermediate\nfriction. This correlation disappears in the large friction limit."
    },
    {
        "anchor": "Polar Smectic Films: We report on a new experimental procedure for forming and studying polar\nsmectic liquid crystal films. A free standing smectic film is put in contact\nwith a liquid drop, so that the film has one liquid crystal/liquid interface\nand one liquid crystal/air interface. This polar environment results in changes\nin the textures observed in the film, including a boojum texture and a\npreviously unobserved spiral texture in which the winding direction of the\nspiral reverses at a finite radius from its center. Some aspects of these\ntextures are explained by the presence of a Ksb term in the bulk elastic free\nenergy density that favors a combination of splay and bend deformations.",
        "positive": "Hydrodynamic Pair Attractions Between Driven Colloidal Particles: Colloidal spheres driven through water along a circular path by an optical\nring trap display unexpected dynamical correlations. We use Stokesian Dynamics\nsimulations and a simple analytical model to demonstrate that the path's\ncurvature breaks the symmetry of the two-body hydrodynamic interaction,\nresulting in particle pairing. The influence of this effective nonequilibrium\nattraction diminishes as either the temperature or the stiffness of the radial\nconfinement increases. We find a well defined set of dynamically paired states\nwhose stability relies on hydrodynamic coupling in curving trajectories."
    },
    {
        "anchor": "Hidden symmetries generate rigid folding mechanisms in periodic origami: We consider the zero-energy deformations of periodic origami sheets with\ngeneric crease patterns. Using a mapping from the linear folding motions of\nsuch sheets to force-bearing modes in conjunction with the Maxwell-Calladine\nindex theorem we derive a relation between the number of linear folding motions\nand the number of rigid body modes that depends only on the average\ncoordination number of the origami's vertices. This supports the recent result\nby Tachi which shows periodic origami sheets with triangular faces exhibit\ntwo-dimensional spaces of rigidly foldable cylindrical configurations. We also\nfind, through analytical calculation and numerical simulation, branching of\nthis configuration space from the flat state due to geometric compatibility\nconstraints that prohibit finite Gaussian curvature. The same counting argument\nleads to pairing of spatially varying modes at opposite wavenumber in\ntriangulated origami, preventing topological polarization but permitting a\nfamily of zero energy deformations in the bulk that may be used to reconfigure\nthe origami sheet.",
        "positive": "Bulk fluid phase behaviour of colloidal platelet-sphere and\n  platelet-polymer mixtures: Using a geometry-based fundamental measure density functional theory, we\ncalculate bulk fluid phase diagrams of colloidal mixtures of vanishingly thin\nhard circular platelets and hard spheres. We find isotropic-nematic phase\nseparation with strong broadening of the biphasic region upon increasing the\npressure. In mixtures with large size ratio of platelet and sphere diameter,\nthere is also demixing between two nematic phases with differing platelet\nconcentrations. We formulate a fundamental-measure density functional for\nmixtures of colloidal platelets and freely overlapping spheres, which represent\nideal polymers, and use it to obtain phase diagrams. We find that for low\nplatelet-polymer size ratio in addition to isotropic-nematic and\nnematic-nematic phase coexistence, platelet-polymer mixtures also display\nisotropic-isotropic demixing. In contrast, we do not find isotropic-isotropic\ndemixing in hard core platelet-sphere mixtures for the size ratios considered."
    },
    {
        "anchor": "Computation of the Hydrodynamic Radius of Charged Nanoparticles from\n  Non-equilibrium Molecular Dynamics: We have used non-equilibrium molecular dynamics to simulate the flow of water\nmolecules around a charged nanoparticle described at the atomic scale. These\nnon-equilibrium simulations allowed us to compute the friction coefficient of\nthe nanoparticle and then to deduce its hydrodynamic radius. We have compared\ntwo different strategies to thermostat the simulation box, since the low\nsymmetry of the flow field renders the control of temperature non trivial. We\nshow that both lead to an adequate control of the temperature of the system. To\ndeduce the hydrodynamic radius of the nanoparticle we have employed a partial\nthermostat, which exploits the cylindrical symmetry of the flow field. Thereby,\nonly a part of the simulation box far from the nanoparticle is thermostated. We\nhave taken into account the finite concentration of the nanoparticle by using\nthe result of Hasimoto (J. Fluid. Mech. {\\bf 1959}, {\\it 5}, 317-328 ) for the\nfriction force in a periodic cubic array of spheres. We have focused on the\ncase of polyoxometalate ions, which are inorganic charged nanoparticles. It\nappears that, for a given structure of the nanoparticle at the atomic level,\nthe hydrodynamic radius significantly increases with the nanoparticle's charge,\na phenomenon that had not been quantified so far using molecular dynamics. The\npresence of an added salt only slightly modifies the hydrodynamic radius.",
        "positive": "In Situ Simultaneous Measuring Forces Acted on Individual Legs of Water\n  Striders According to Archimedes' Principle: The supporting forces of all the legs have been simultaneously measured\nthrough a natural phenomenon inspired shadow method, by capturing water strider\nleg shadows to calculate the expelled water volume and the equivalent floating\nforces according to Archimedes' principle, with a sensitivity up to\nnN~pN/pixel. The method was verified by comparing to electronic balance to\nweight water striders. The supporting force acted on legs was found to linearly\nproportional to its shadow area, which geometry clearly indicated the\nhydrophobicity of legs. The pressed depth of legs, vertical weight focus\nposition change and body pitch angle during leg refreshing, sculling and\njumping forward of water striders have been achieved with resolutions of\n5um/pixel, 2 um/pixel, and 0.02 degree, respectively, which is difficult for\ngeneral imaging technologies. The shadow method was also developed into a force\nmeasuring device and characterized the adhesion force of a hair/polymer surface\ncontact in a few uN with a 0.3 nN/pixel resolution."
    },
    {
        "anchor": "Generalized Three-Sphere Microswimmers: Among several models for microswimmers, the three-sphere microswimmer\nproposed by Najafi and Golestanian captures the essential mechanism for the\nlocomotion of a microswimmer in a viscous fluid. Owing to its simplicity and\nflexibility, the original three-sphere model has been extended and generalized\nin various ways to discuss new swimming mechanisms of microswimmers. We shall\nprovide a systematic and concise review of the various extensions of the\nthree-sphere microswimmers that have been developed by the present authors. In\nparticular, we shall discuss the following seven cases; elastic, thermal, odd,\nautonomous three-sphere microswimmers; two interacting ones; and those in\nviscoelastic and structured fluids. The well-known Purcell's scallop theorem\ncan be generalized for stochastic three-sphere microswimmers and also for the\nlocomotion in viscoelastic and structured fluids.",
        "positive": "Curvature-driven, One-step Assembly of Reconfigurable Smectic Liquid\n  Crystal \"Compound Eye\" Lenses: Confined smectic A liquid crystals (SmA LCs) form topological defects called\nfocal conic domains (FCDs) that focus light as gradient-index lenses. Here, we\nexploit surface curvature to self-assemble FCDs in a single step into a\nhierarchical structure (coined \"flower pattern\") molded by the fluid interface\nthat is pinned at the top of a micropillar. The structure resembles the\ncompound eyes of some invertebrates, which consist of hundreds of microlenses\non a curved interface, able to focus and construct images in three dimensions.\nHere we demonstrate that these flowers are indeed \"compound eyes\" with\nimportant features which have not been demonstrated previously in the\nliterature. The eccentric FCDs gradually change in size with radial distance\nfrom the edge of the micropillar, resulting in a variable microlens focal\nlength that ranges from a few microns to a few tens of microns within a single\n\"flower\". We show that the microlenses can construct a composite 3D image from\ndifferent depth of field. Moreover, the smectic \"compound eye\" can be\nreconfigured by heating and cooling at the LC phase transition temperature; its\nfield of view can be manipulated by tuning the curvature of the LC interface,\nand the lenses are sensitive to light polarization."
    },
    {
        "anchor": "Interacting particles in an activity landscape: We study interacting active Brownian particles (ABPs) with a space-dependent\nswim velocity via simulation and theory. We find that, although an equation of\nstate exists, a mechanical equilibrium does not apply to ABPs in activity\nlandscapes. The pressure difference originates in the flux of polar order and\nthe gradient of swim velocity across the interface between regions of different\nactivity. In contrast to motility-induced phase separation of ABPs with a\nhomogeneous swim velocity, a critical point does not exist for an\nactive-passive patch system, which continuously splits into a dense and a\ndilute phase with increasing activity. However, if the global density is so\nhigh that not all particles can be packed onto the inactive patch, then\nMIPS-like behavior is restored and the pressure is balanced again.",
        "positive": "The influence of an applied magnetic field on the self-assembly of\n  magnetic nanogels: Using Langevin dynamics simulations, we investigate the self-assembly of\nmagnetic nanogels in the presence of applied magneticfields of moderate\nstrength. We find that even weak fields lead to drastic changes in the\nstructure factors of both, the embeddedmagnetic nanoparticles and of whole\nnanogel particles. Nanogels assemble by uniting magnetic particle clusters\nforming inter-gelbridges. At zero field the average amount of such bridges for\na pair of nanogels is close to one, whereas even for weak fields itfastly\ndoubles. Rapid growth of cluster size at low values of the applied field is\nfollowed by a broad region of slow increase, causedby the mechanical\nconstraints imposed the polymer matrix. The influence of the latter manifests\nitself in both, the slow growth ofthe magnetisation curve at intermediate\nfields and the slow decay of the total Zeeman energy."
    },
    {
        "anchor": "A Tuneable Magnetic Domain Wall Conduit Regulating Nanoparticle\n  Diffusion: We demonstrate a general and robust method to confine on a plane strongly\ndiffusing submicrometer particles in water by using size tunable magnetic\nchannels. These virtual conduits are realized with pairs of movable Bloch walls\n(BWs) located within an epitaxially grown ferrite garnet film. We show that,\nonce inside the magnetic conduit, the particles experience an effective local\nparabolic potential in the transverse direction, while freely diffusing along\nthe conduit. The stiffness of the magnetic potential is determined as a\nfunction of field amplitude which varies the width of the magnetic channel, and\nprecise control of the degree of confinement is demonstrated by tuning the\napplied field. The magnetic conduit is then used to realize single files of\nnon-passing particles and to induce periodic condensation of an ensemble of\nparticles into parallel stripes in a completely controllable and reversible\nmanner.",
        "positive": "Statistics of Quenched Defects Containing Semi-Flexible Polymer Chain:\n  Exact Results (II): We describe method to discuss thermodynamics of a defected semi-flexible\nhomo-polymer chain in the two and three dimensions using fully directed\nself-avoiding walk lattice model. The defects are located along a line and\nthese defects are not in the thermal equilibrium with the monomers of the\nsemi-flexible polymer chain; i. e. we consider the case of defected\nsemi-flexible polymer chain in the present manuscript for the case of quenched\ndefects. There are m defects on the conformations of the N monomers long\nsemi-flexible polymer chain and we exactly count the number of Q realizations\nof the defected conformations of N-monomers long self-avoiding semi-flexible\npolymer chain; and thus we derive the exact expression of the free energy of\nthe defected semi-flexible polymer chain for the finite length (i. e. using the\nfixed particle ensemble method); and we also derive exact expression of the\npartition function for the defected self-avoiding semi-flexible polymer chain\nin the thermodynamic limit using the grand canonical ensemble theory. The\nmethod described in this manuscript may be easily extended to another case of\nthe defected polymer chain for isotropic/directed walk lattice models."
    },
    {
        "anchor": "Bayesian analysis of time series of single RNA under fluctuating force: Extracting the intrinsic kinetic information of biological molecule from its\nsingle-molecule kinetic data is of considerable biophysical interest. In this\nwork, we theoretically investigate the feasibility of inferring single RNA's\nintrinsic kinetic parameters from the time series obtained by forced\nfolding/unfolding experiment done in the light tweezer, where the molecule is\nflanked by long double-stranded DNA/RNA handles and tethered between two big\nbeads. We first construct a coarse-grain physical model of the experimental\nsystem. The model has captured the major physical factors: the Brownian motion\nof the bead, the molecular structural transition, and the elasticity of the\nhandles and RNA. Then based on an analytic solution of the model, a Bayesian\nmethod using Monte Carlo Markov Chain is proposed to infer the intrinsic\nkinetic parameters of the RNA from the noisy time series of the distance or\nforce. Because the force fluctuation induced by the Brownian motion of the bead\nand the structural transition can significantly modulate the transition rates\nof the RNA, we prove that, this statistic method is more accurate and efficient\nthan the conventional histogram fitting method in inferring the molecule's\nintrinsic parameters.",
        "positive": "Multiple polar and non-polar nematic phases: Liquid crystal materials exhibiting up to three nematic phases are reported.\nDielectric response measurements show that while the lower temperature nematic\nphase has ferroelectric order and the highest temperature nematic phase is\napolar, the intermediate phase has local antiferroelectric order. The\nmodification of the molecular structure by increasing the number of lateral\nfluorine substituents leads to one of the materials showing a direct\nisotropic-ferronematic phase transition."
    },
    {
        "anchor": "Above and beyond: Holographic tracking of axial displacements in\n  holographic optical tweezers: How far a particle moves along the optical axis in a holographic optical trap\nis not simply dictated by the programmed motion of the trap, but rather depends\non an interplay of the trap's changing shape and the particle's material\nproperties. For the particular case of colloidal spheres in optical tweezers,\nholographic video microscopy reveals that trapped particles tend to move\nfarther along the axial direction than the traps that are moving them and that\ndifferent kinds of particles move by different amounts. These surprising and\nsizeable variations in axial placement can be explained by a dipole-order\ntheory for optical forces. Their discovery highlights the need for real-time\nfeedback to achieve precise control of colloidal assemblies in three dimensions\nand demonstrates that holographic microscopy can meet that need.",
        "positive": "Universality of monopole mode and time evolution of a d-dimensional\n  trapped interacting Bose gas: We study a generalised Gross-Pitaevskii equation describing a d-dimensional\nharmonic trapped (with trap frequency $\\omega_{0}$) weakly interacting Bose gas\nwith a non-linearity of order (2 k + 1) and scaling exponent (n) of the\ninteraction potential. Using the time-dependent variational analysis, we\nexplicitly show that for a particular combination of n, k and d, the\ngeneralised GP equation has the universal monopole oscillation frequency $2\n\\omega_{0}$. We also find that the time-evolution of the width can be described\nuniversally by the same Hill's equation if the system satisfy that particular\ncombination. We also obtain the condition for the exact self-similar solutions\nof the Gross-Pitaevskii equation. As an application, we discuss low dimensional\ntrapped Bose condensate state and Calogero model."
    },
    {
        "anchor": "Shear viscosity and shear thinning in two-dimensional Yukawa liquids: A two-dimensional Yukawa liquid is studied using two different nonequilibrium\nmolecular dynamics simulation methods. Shear viscosity values in the limit of\nsmall shear rates are reported for a wide range of Coulomb coupling parameter\nand screening length. At high shear rates it is demonstrated that this liquid\nexhibits shear thinning, i.e., the viscosity $\\eta$ diminishes with increasing\nshear rate. It is expected that two-dimensional dusty plasmas will exhibit this\neffect.",
        "positive": "Dynamics of Bose-Einstein condensates in cigar-shaped traps: Gross-Pitaevskii equation for Bose-Einstein condensate confined in elongated\ncigar-shaped trap is reduced to an effective system of nonlinear equations\ndepending on only one space coordinate along the trap axis. The radial\ndistribution of the condensate density and its radial velocity are approximated\nby Gaussian functions with real and imaginary exponents, respectively, with\nparameters depending on the axial coordinate and time. The effective\none-dimensional system is applied to description of the ground state of the\ncondensate, to dark and bright solitons, to the sound and radial compression\nwaves propagating in a dense condensate, and to weakly nonlinear waves in\nrepulsive condensate. In the low density limit our results reproduce the known\nformulae. In the high density case our description of solitons goes beyond the\nstandard approach based on the nonlinear Schr\\\"odinger equation. The dispersion\nrelations for the sound and radial compression waves are obtained in a wide\nregion of values of the condensate density. Korteweg-de Vries equation for\nweakly nonlinear waves is derived and existence of bright solitons on a\nconstant background is predicted for the dense enough condensate with repulsive\ninteraction between the atoms."
    },
    {
        "anchor": "From fifty years ago, the birth of modern liquid-state science: The story told in this autobiographical perspective begins fifty years ago at\nthe 1967 Gordon Research Conference on the Physics and Chemistry of Liquids. It\ntraces developments in liquid-state science from that time, including\ncontributions from the author, and especially in the study of liquid water. It\nemphasizes the importance of fluctuations, and the challenges of\nfar-from-equilibrium phenomena.",
        "positive": "On Exact Solutions to the Cylindrical Poisson-Boltzmann Equation with\n  Applications to Polyelectrolytes: Using exact results from the theory of completely integrable systems of the\nPainleve/Toda type, we examine the consequences for the theory of\npolyelectrolytes in the (nonlinear) Poisson-Boltzmann approximation."
    },
    {
        "anchor": "Effective single component description of steady state structures of\n  passive particles in an active bath: We model a binary mixture of passive and active Brownian particles in two\ndimensions using the effective interaction between passive particles in the\nactive bath. The activity of active particles and the size ratio of two types\nof particles are two control parameters in the system. The effective\ninteraction is calculated from the average force on two particles generated by\nthe active particles. The effective interaction can be attractive or repulsive,\ndepending on the system parameters. The passive particles form four distinct\nstructural orders for different system parameters viz; disorder (D), disordered\ncluster (DC), ordered cluster (OC), and poly-crystalline order (P C). The\nchange in structure is dictated by the change in nature of the effective\ninteraction. We further confirm the four structures using full microscopic\nsimulation of active and passive mixture. Our study is useful to understand the\ndifferent collective behaviour in non-equilibrium systems.",
        "positive": "Thermodynamic Interpretation of Soft Glassy Rheology Models: Mesoscopic models play an important role in our understanding of the\ndeformation and flow of amorphous materials. One such description, based on the\nShear Transformation Zone (STZ) theory, has recently been re-formulated within\na non-equilibrium thermodynamics framework, and found to be consistent with it.\nWe show here that a similar interpretation can be made for the Soft Glassy\nRheology (SGR) model. Conceptually this means that the \"noise temperature\" x,\nproposed phenomenologically in the SGR model to control the dynamics of a set\nof slow mesoscopic degrees of freedom, can consistently be interpreted as their\nactual thermodynamic temperature. (Because such modes are slow to equilibrate,\nthis generally does not coincide with the temperature of the fast degrees of\nfreedom and/or heat bath.) If one chooses to make this interpretation, the\nthermodynamic framework significantly constrains extensions of the SGR approach\nto models in which x is a dynamical variable. We assess in this light some such\nextensions recently proposed in the context of shear banding."
    },
    {
        "anchor": "Arch-based configurations in the volume ensemble of static granular\n  systems: We propose an alternative approach to count the microscopic static\nconfigurations of granular packs under gravity by considering arches. This\nstrategy simplifies the problem of filtering out configurations that are not\nmechanically stable, opening the way for a range of granular models to be\nstudied via ensemble theory. Following this arch-based approach, we have\nobtained the exact density of states for a two-dimensional non-interacting\nrigid arch model of granular assemblies. The calculated arch size distribution\nand volume fluctuations show qualitative agreement with realistic simulations\nof tapped granular beds. We have also validated our calculations by comparing\nwith the analytic solution for the limiting case of a quasi-one-dimensional\ncolumn of frictionless disks.",
        "positive": "Stretching and squeezing of sessile dielectric drops by the optical\n  radiation pressure: We study numerically the deformation of sessile dielectric drops immersed in\na second fluid when submitted to the optical radiation pressure of a continuous\nGaussian laser wave. Both drop stretching and drop squeezing are investigated\nat steady state where capillary effects balance the optical radiation pressure.\nA boundary integral method is implemented to solve the axisymmetric Stokes flow\nin the two fluids. In the stretching case, we find that the drop shape goes\nfrom prolate to near-conical for increasing optical radiation pressure whatever\nthe drop to beam radius ratio and the refractive index contrast between the two\nfluids. The semi-angle of the cone at equilibrium decreases with the drop to\nbeam radius ratio and is weakly influenced by the index contrast. Above a\nthreshold value of the radiation pressure, these \"optical cones\" become\nunstable and a disruption is observed. Conversely, when optically squeezed, the\ndrop shifts from an oblate to a concave shape leading to the formation of a\nstable \"optical torus\". These findings extend the electrohydrodynamics approach\nof drop deformation to the much less investigated \"optical domain\" and reveal\nthe openings offered by laser waves to actively manipulate droplets at the\nmicrometer scale."
    },
    {
        "anchor": "Quasicrystals in a Monodisperse System: We investigate the formation of a two-dimensional quasicrystal in a\nmonodisperse system, using molecular dynamics simulations of hard sphere\nparticles interacting via a two-dimensional square-well potential. We find that\nmore than one stable crystalline phase can form for certain values of the\nsquare-well parameters. Quenching the liquid phase at a very low temperature,\nwe obtain an amorphous phase. By heating this amorphous phase, we obtain a\nquasicrystalline structure with five-fold symmetry. From estimations of the\nHelmholtz potentials of the stable crystalline phases and of the quasicrystal,\nwe conclude that the observed quasicrystal phase can be the stable phase in a\nspecific range of temperatures.",
        "positive": "Jamming in Systems Composed of Frictionless Ellipse-Shaped Particles: We study the structural and mechanical properties of jammed ellipse packings,\nand find that the nature of the jamming transition in these systems is\nfundamentally different from that for spherical particles. Ellipse packings are\ngenerically hypostatic with more degrees of freedom than constraints. The\nspectra of low energy excitations possess two gaps and three distinct branches\nover a range of aspect ratios. In the zero compression limit, the energy of the\nmodes in the lowest branch increases {\\it quartically} with deformation\namplitude, and the density of states possesses a $\\delta$-function at zero\nfrequency. We identify scaling relations that collapse the low-frequency part\nof the spectra for different aspect ratios. Finally, we find that the degree of\nhypostaticity is determined by the number of quartic modes of the packing."
    },
    {
        "anchor": "Effect of colloidal charge discretization in the primitive model: The effect of fixed discrete colloidal charges in the primitive model is\ninvestigated for spherical macroions. Instead of considering a central bare\ncharge, as it is traditionally done, we distribute \\textit{discrete} charges\nrandomly on the sphere. We use molecular dynamics simulations to study this\neffect on various properties such as overcharging, counterion distribution and\ndiffusion. In the vicinity of the colloid surface the electrostatic potential\nmay considerably differ from the one obtained with a central charge. In the\nstrong Coulomb coupling, we showed that the colloidal charge discretization\nqualitatively influences the counterion distribution and leads to a strong\ncolloidal charge-counterion pair association. However, we found that\n\\textit{charge inversion} still persists even if strong pair association is\nobserved.",
        "positive": "Experimental studies of equilibrium vortex properties in a\n  Bose-condensed gas: We characterize several equilibrium vortex effects in a rotating\nBose-Einstein condensate. Specifically we attempt precision measurements of\nvortex lattice spacing and the vortex core size over a range of condensate\ndensities and rotation rates. These measurements are supplemented by numerical\nsimulations, and both experimental and numerical data are compared to theory\npredictions of Sheehy and Radzihovsky [17] (cond-mat/0402637) and Baym and\nPethick [25] (cond-mat/0308325). Finally, we study the effect of the\ncentrifugal weakening of the trapping spring constants on the critical\ntemperature for quantum degeneracy and the effects of finite temperature on\nvortex contrast."
    },
    {
        "anchor": "Critical Casimir interactions around the consolute point of a binary\n  solvent: Spatial confinement of a near-critical medium changes its fluctuation\nspectrum and modifies the corresponding order parameter distribution. These\neffects result in effective, so-called critical Casimir forces (CCFs) acting on\nthe confining surfaces. These forces are attractive for like boundary\nconditions of the order parameter at the opposing surfaces of the confinement.\nFor colloidal particles dissolved in a binary liquid mixture acting as a\nsolvent close to its critical point of demixing, one thus expects the emergence\nof phase segregation into equilibrium colloidal liquid and gas phases. We\nanalyze how such phenomena occur asymmetrically in the whole thermodynamic\nneighborhood of the consolute point of the binary solvent. By applying\nfield-theoretical methods within mean-field approximation and the\nsemi-empirical de Gennes-Fisher functional, we study the CCFs acting between\nplanar parallel walls as well as between two spherical colloids and their\ndependence on temperature and on the composition of the near-critical binary\nmixture. We find that for compositions slightly poor in the molecules\npreferentially adsorbed at the surfaces, the CCFs are significantly stronger\nthan at the critical composition, thus leading to pronounced colloidal\nsegregation. The segregation phase diagram of the colloid solution following\nfrom the calculated effective pair potential between the colloids agrees\nsurprisingly well with experiments and simulations.",
        "positive": "How super-tough gels break: Fracture of highly stretched materials challenges our view of how things\nbreak. We directly visualize rupture of tough double-network (DN) gels at >50\\%\nstrain. During fracture, crack tip shapes obey a $x\\sim y^{1.6}$ power-law, in\ncontrast to the parabolic profile observed in low-strain cracks. A new\nlength-scale $\\ell$ emerges from the power-law; we show that $\\ell$ scales\ndirectly with the stored elastic energy, and diverges when the crack velocity\napproaches the shear wave speed. Our results show that DN gels undergo brittle\nfracture, and provide a testing ground for large-strain fracture mechanics."
    },
    {
        "anchor": "Metastability of a granular surface in a spinning bucket: The surface shape of a spinning bucket of granular material is studied using\na continuum model of surface flow developed by Bouchaud et al. and Mehta et al.\nAn experimentally observed central subcritical region is reproduced by the\nmodel. The subcritical region occurs when a metastable surface becomes unstable\nvia a nonlinear instability mechanism. The nonlinear instability mechanism\ndestabilizes the surface in large systems while a linear instability mechanism\nis relevant for smaller systems. The range of angles in which the granular\nsurface is metastable vanishes with increasing system size.",
        "positive": "Chain reconfiguration in active noise: In a typical single molecule experiment, dynamics of an unfolded proteins is\nstudied by determining the reconfiguration time using long-range Forster\nresonance energy transfer where the reconfiguration time is the characteristic\ndecay time of the position correlation between two residues of the protein. In\nthis paper we theoretically calculate the reconfiguration time for a single\nflexible polymer in presence of active noise. The study suggests that though\nthe MSD grows faster, the chain reconfiguration is always slower in presence of\nlong-lived active noise with exponential temporal correlation. Similar behavior\nis observed for a worm like semi-flexible chain and a Zimm chain. However it is\nprimarily the characteristic correlation time of the active noise and not the\nstrength that controls the increase in the reconfiguration time. In a nutshell,\nsuch active noise makes the polymer to move faster but the correlation loss\nbetween the monomers becomes slower."
    },
    {
        "anchor": "Non-metric interaction rules in models of active matter: It is common in the study of a dizzying array of soft matter systems to\nperform agent-based simulations of particles interacting via conservative and\noften short-ranged forces. In this context, well-established algorithms for\nefficiently computing the set of pairs of interacting particles have\nestablished excellent open-source packages to efficiently simulate large\nsystems over long time scales -- a crucial consideration given the separation\nin time- and length-scales often observed in soft matter. What happens, though,\nwhen we think more broadly about what it means to construct a neighbor list?\nWhat if interactions are non-reciprocal, or if the \"range\" of an interaction is\ndetermined not by a distance scale but according to some other consideration?\nAs the field of soft and active matter increasingly considers the properties of\nliving matter -- from the cellular to the super-organismal scale -- these\nquestions become increasingly relevant, and encourage us to think about new\nphysical and computational paradigms in the modeling of active matter. In this\nchapter we examine case studies in the use of non-metric interactions.",
        "positive": "Non-Equilibrium Living Polymers: Systems of \"living\" polymers are ubiquitous in industry and are traditionally\nrealised using surfactants. Here I review the state-of-the-art of living\npolymers and discuss non-equilibrium extensions that may be realised with\nadvanced synthetic chemistry or DNA functionalised by proteins. These systems\nare not only interesting in order to realise novel \"living\" soft matter but can\nalso shed insight into how genomes are (topologically) regulated in vivo."
    },
    {
        "anchor": "Flow of wet granular materials: a numerical study: We simulate dense assemblies of frictional spherical grains in steady shear\nflow under controlled normal stress $P$ in the presence of a small amount of an\ninterstitial liquid, which gives rise to capillary menisci, assumed isolated\n(pendular regime), and to attractive forces. The system behavior depends on two\ndimensionless control parameters: inertial number $I$ and reduced pressure\n$P^*=aP/(\\pi\\Gamma)$, comparing confining forces $\\sim a^2P$ to meniscus\ntensile strength $F_0=\\pi\\Gamma a$, for grains of diameter $a$ joined by\nmenisci with surface tension $\\Gamma$. We pay special attention to the\nquasi-static limit of slow flow and observe systematic, enduring strain\nlocalization in some of the cohesion-dominated ($P^*\\sim 0.1$) systems.\nHomogeneous steady flows are characterized by the dependence of internal\nfriction coefficient $\\mu^*$ and solid fraction $\\Phi$ on $I$ and $P^*$. We\nrecord fairly small but not negligible normal stress differences and the\nmoderate sensitivity of the system to saturation within the pendular regime.\nCapillary forces have a significant effect on the macroscopic behavior of the\nsystem, up to $P^*$ values of several units. The concept of effective pressure\nmay be used to predict an order of magnitude for the strong increase of $\\mu^*$\nas $P^*$ decreases but such a crude approach is unable to account for the\ncomplex structural changes induced by capillary cohesion. Likewise, the\nMohr-Coulomb criterion for pressure-dependent critical states is, at best, an\napproximation valid within a restricted range of pressures, with $P^*\\ge 1$. At\nsmall enough $P^*$, large clusters of interacting grains form in slow flows, in\nwhich liquid bonds survive shear strains of several units. This affects the\nanisotropies associated to different interactions, and the shape of function\n$\\mu^*(I)$, which departs more slowly from its quasistatic limit than in\ncohesionless systems.",
        "positive": "Supershear surface waves reveal prestress and anisotropy of soft\n  materials: Surface waves play important roles in many fundamental and applied areas from\nseismic detection to material characterizations. Supershear surface waves with\npropagation speeds greater than bulk shear waves have recently been reported,\nbut their properties are not well understood. In this Letter, we describe\ntheoretical and experimental results on supershear surface waves in rubbery\nmaterials. We find that supershear surface waves can be supported in\nviscoelastic materials with no restriction on the shear quality factor.\nInterestingly, the effect of prestress on the speed of the supershear surface\nwave is opposite to that of the Rayleigh surface wave. Furthermore, anisotropy\nof material affects the supershear wave much more strongly than the Rayleigh\nsurface wave. We offer heuristic interpretation as well as theoretical\nverification of our experimental observations. Our work points to the potential\napplications of supershear waves for characterizing the bulk mechanical\nproperties of soft solid from the free surface."
    },
    {
        "anchor": "Hydrodynamics of bilayer membranes with diffusing transmembrane proteins: We consider the hydrodynamics of lipid bilayers containing transmembrane\nproteins of arbitrary shape. This biologically-motivated problem is relevant to\nthe cell membrane, whose fluctuating dynamics play a key role in phenomena\nranging from cell migration, intercellular transport, and cell communication.\nUsing Onsager's variational principle, we derive the equations that govern the\nrelaxation dynamics of the membrane shape, of the mass densities of the bilayer\nleaflets, and of the diffusing proteins' concentration. With our generic\nformalism, we obtain several results on membrane dynamics. We find that\nproteins that span the bilayer increase the intermonolayer friction\ncoefficient. The renormalization, which can be significant, is in inverse\nproportion to the protein's mobility. Second, we find that asymmetric proteins\ncouple to the membrane curvature and to the difference in monolayer densities.\nFor practically all accessible membrane tensions ($\\sigma> 10^{-8}$ N/m) we\nshow that the protein density is the slowest relaxing variable. Furthermore,\nits relaxation rate decreases at small wavelengths due to the coupling to\ncurvature. We apply our formalism to the large-scale diffusion of a\nconcentrated protein patch. We find that the diffusion profile is not\nself-similar, owing to the wavevector dependence of the effective diffusion\ncoefficient.",
        "positive": "Resolving Dynamic Properties of Polymers through Coarse-Grained\n  Computational Studies: Coupled length and time scales determine the dynamic behavior of polymers and\nunderlie their unique viscoelastic properties. To resolve the long-time\ndynamics it is imperative to determine which time and length scales must be\ncorrectly modeled. Here we probe the degree of coarse graining required to\nsimultaneously retain significant atomistic details and access large length and\ntime scales. The degree of coarse graining in turn sets the minimum length\nscale instrumental in defining polymer properties and dynamics. Using linear\npolyethylene as a model system, we probe how coarse graining scale affects the\nmeasured dynamics. Iterative Boltzmann inversion is used to derive\ncoarse-grained potentials with 2-6 methylene groups per coarse-grained bead\nfrom a fully atomistic melt simulation. We show that atomistic detail is\ncritical to capturing large scale dynamics. Using these models we simulate\npolyethylene melts for times over 500 {\\mu}s to study the viscoelastic\nproperties of well-entangled polymer chains."
    },
    {
        "anchor": "Signal Transmissibility in Marginal Granular Materials: We examine the \"transmissibility\" of a simulated two-dimensional pack of\nfrictionless disks formed by confining dilute disks in a shrinking, periodic\nbox to the point of mechanical stability. Two opposite boundaries are then\nremoved, thus allowing a set of free motions. Small free displacements on one\nboundary then induce proportional displacements on the opposite boundary.\nTransmissibility is the ability to distinguish different perturbations by their\ndistant responses. We assess transmissibility by successively identifying free\northonormal modes of motion that have the {\\em smallest} distant responses. The\nlast modes to be identified in this \"pessimistic\" basis are the most\ntransmissive. The transmitted amplitudes of these most transmissive modes fall\noff exponentially with mode number. Similar exponential falloff is seen in a\nsimple elastic medium, though the responsible modes differ greatly in structure\nin the two systems. Thus the marginal pack's transmissibility is qualitatively\nsimilar to that of a simple elastic medium. We compare our results with recent\nfindings based on the projection of the space of free motion onto interior\nsites.",
        "positive": "The flow rate of granular materials through an orifice: The flow rate of grains through large orifices is known to be dependent on\nits diameter to a 5/2 power law. This relationship has been checked for big\noutlet sizes, whereas an empirical fitting parameter is needed to reproduce the\nbehavior for small openings.\n  In this work, we provide experimental data and numerical simulations covering\na wide span of outlet sizes, both in three and two dimensions. This allows us\nto show that the laws that are usually employed are satisfactory only if a\nsmall range of openings is considered. We propose a new law for the mass flow\nrate of grains that correctly reproduces the data for all the orifice sizes,\nincluding the behaviors for very large and very small outlet sizes."
    },
    {
        "anchor": "Modeling two-state cooperativity in protein folding: A protein model with the pairwise interaction energies varying as local\nenvironment changes, i.e., including some kinds of collective effect between\nthe contacts, is proposed. Lattice Monte Carlo simulations on the\nthermodynamical characteristics and free energy profile show a well-defined\ntwo-state behavior and cooperativity of folding for such a model. As a\ncomparison, related simulations for the usual G\\={o} model, where the\ninteraction energies are independent of the local conformations, are also made.\nOur results indicate that the evolution of interactions during the folding\nprocess plays an important role in the two-state cooperativity in protein\nfolding.",
        "positive": "Convolutional Neural Networks for Real-Time Localization and\n  Classification in Feedback Digital Microscopy: We present an adapted single-shot convolutional neural network (YOLOv2) for\nthe real-time localization and classification of particles in optical\nmicroscopy. As compared to previous works, we focus on the real-time detection\ncapabilities of the system to allow for manipulation of microscopic objects in\nlarge heterogeneous ensembles with the help of feedback control. The network is\ncapable of localizing and classifying several hundreds of microscopic objects\neven at very low signal-to-noise ratios for images as large as 416x416 pixels\nwith an inference time of about 10 ms. We demonstrate the real-time detection\nperformance by manipulating active particles propelled by laser-induced\nself-thermophoresis. In order to make our framework readily available for\nothers, we provide all scripts and source code. The network is implemented in\nPython/Keras using the TensorFlow backend. A C library supporting GPUs is\nprovided for the real-time inference."
    },
    {
        "anchor": "Disorder-assisted melting and the glass transition in amorphous solids: The mechanical response of solids depends on temperature because the way\natoms and molecules respond collectively to deformation is affected at various\nlevels by thermal motion. This is a fundamental problem of solid state science\nand plays a crucial role in metallurgy, aerospace engineering, energy. In\nglasses the vanishing of rigidity upon increasing temperature is the reverse\nprocess of the glass transition. It remains poorly understood due to the\ndisorder leading to nontrivial (nonaffine) components in the atomic\ndisplacements. Our theory explains the basic mechanism of the melting\ntransition of amorphous (disordered) solids in terms of the lattice energy lost\nto this nonaffine motion, compared to which thermal vibrations turn out to play\nonly a negligible role. It predicts the square-root vanishing of the shear\nmodulus $G\\sim\\sqrt{T_{c}-T}$ at criticality observed in the most recent\nnumerical simulation study. The theory is also in good agreement with classic\ndata on melting of amorphous polymers (for which no alternative theory can be\nfound in the literature) and offers new opportunities in materials science.",
        "positive": "Analysis of Two-State Folding Using Parabolic Approximation IV:\n  Non-Arrhenius Kinetics of FBP28 WW Part-II: A model which treats the denatured and the native conformers as being\nconfined to harmonic Gibbs energy wells has been used to rationalize the\nphysical basis for the non-Arrhenius behaviour of spontaneously-folding fixed\ntwo-state systems. It is shown that at constant pressure and solvent\nconditions: (i) the rate constant for folding will be a maximum when the heat\nreleased upon formation of net molecular interactions is exactly compensated by\nthe heat absorbed to desolvate net polar and non-polar solvent accessible\nsurface area (SASA), as the denatured conformers driven by thermal noise bury\ntheir SASA and diffuse on the Gibbs energy surface to reach the activated\nstate; (ii) the rate constant for unfolding will be a minimum when the heat\nabsorbed by the native conformers to break various net backbone and sidechain\ninteractions is exactly compensated by the heat of hydration released due to\nthe net increase in SASA, as the native conformers unravel to reach the\nactivated state; (iii) the activation entropy for folding will be zero, and the\nGibbs barrier to folding will be a minimum, when the decrease in the backbone\nand the sidechain mobility is exactly compensated by the increase in entropy\ndue to solvent-release, as the denatured conformers bury their SASA to reach\nthe activated state; and (iv) the activation entropy for unfolding will be\nzero, and the Gibbs barrier to unfolding will be a maximum when the increase in\nthe backbone and sidechain mobility is exactly compensated by the negentropy of\nsolvent capture on the protein surface, as the native conformers unravel to\nreach the activated state."
    },
    {
        "anchor": "Wetting and drying of a rigid substrate under variation of the\n  microscopic details: Wetting and drying of a rigid substrate by a Lennard-Jones fluid in molecular\ndynamics simulations is reported. The size of the substrate particles, being\nsmaller than the fluid particles in former simulations, is now taken to be\nequal to, respectively larger than, that of the fluid particles. Recently, for\nthe latter type of system a first order drying transition has been reported.\nLike before we find a continuous-like transition for all systems considered.\nThis also holds for substrates with incompletely-filled top layers, the\nso-called molecularly rough surfaces. All systems studied behave qualitatively\nalike, but inconsistencies are found in the solid-vapour surface tension on\napproach of the wetting transition and for the solid-fluid surface tension in\ngeneral.",
        "positive": "Ogden Material Calibration via Magnetic Resonance Cartography, Parameter\n  Sensitivity, and Variational System Identification: Contemporary material characterisation techniques that leverage deformation\nfields and the weak form of the equilibrium equations face challenges in the\nnumerical solution procedure of the inverse characterisation problem. As\nmaterial models and descriptions differ, so too must the approaches for\nidentifying parameters and their corresponding mechanisms. The widely-used\nOgden material model can be comprised of a chosen number of terms of the same\nmathematical form, which presents challenges of parsimonious representation,\ninterpretability, and stability. Robust techniques for system identification of\nany material model are important to assess and improve experimental design, in\naddition to their centrality to forward computations. Using fully 3D\ndisplacement fields acquired in silicone elastomers with our recently-developed\nmagnetic resonance cartography (MR-u) technique on the order of $>20,000$\npoints per sample, we leverage PDE-constrained optimisation as the basis of\nvariational system identification of our material parameters. We incorporate\nthe statistical F-test to maintain parsimony of representation. Using a new,\nlocal deformation decomposition locally into mixtures of biaxial and uniaxial\ntensile states, we evaluate experiments based on an analytical sensitivity\nmetric, and discuss the implications for experimental design."
    },
    {
        "anchor": "Microstructure and thickening of dense suspensions under extensional and\n  shear flows: Dense suspensions are non-Newtonian fluids which exhibit strong shear\nthickening and normal stress differences. Using numerical simulation of\nextensional and shear flows, we investigate how rheological properties are\ndetermined by the microstructure which is built under flows and by the\ninteractions between particles. By imposing extensional and shear flows, we can\nassess the degree of flow-type dependence in regimes below and above\nthickening. Even when the flow-type dependence is hindered, nondissipative\nresponses, such as normal stress differences, are present and characterise the\nnon-Newtonian behaviour of dense suspensions.",
        "positive": "Synthesis of Silver Colloids: Experiment and Computational Model: We summarize our recent results that model the formation of uniform spherical\nsilver colloids prepared by mixing iso-ascorbic acid and silver-amine complex\nsolutions in the absence of dispersants. We found that the experimental results\ncan be modeled effectively by the two-stage formation mechanism used previously\nto model the preparation of colloidal gold spheres. The equilibrium\nconcentration of silver atoms and the surface tension of silver precursor\nnanocrystals are both treated as free parameters, and the experimental reaction\ntime scale is fit by a narrow region of this two-parameter space. The kinetic\nparameter required to match the final particle size is found to be very close\nto that used previously in modeling the formation of uniform gold particles,\nsuggesting that similar kinetics governs the aggregation process. The model\nalso reproduces semi quantitatively the effects of temperature and solvent\nviscosity on particle synthesis."
    },
    {
        "anchor": "Impalement transitions in droplets impacting microstructured\n  superhydrophobic surfaces: Liquid droplets impacting a superhydrophobic surface decorated with\nmicro-scale posts often bounce off the surface. However, by decreasing the\nimpact velocity droplets may land on the surface in a fakir state, and by\nincreasing it posts may impale droplets that are then stuck on the surface. We\nuse a two-phase lattice-Boltzmann model to simulate droplet impact on\nsuperhydrophobic surfaces, and show that it may result in a fakir state also\nfor reasonable high impact velocities. This happens more easily if the surface\nis made more hydrophobic or the post height is increased, thereby making the\nimpaled state energetically less favourable.",
        "positive": "Theory of a one-dimensional double-X atom interferometer: The dynamics of an atom waveguide X-junction beam splitter becomes truly 1D\nin a regime of low temperatures and densities and large positive scattering\nlengths where the transverse mode becomes frozen and the many-body Schrodinger\ndynamics becomes exactly soluble via a generalized Fermi-Bose mapping theorem.\nWe analyze the interferometric response of a double-X interferometer of this\ntype due to potential differences between the interferometer arms."
    },
    {
        "anchor": "In-situ investigation of temperature induced agglomeration in non-polar\n  magnetic nanoparticle dispersions by small angle X-ray scattering: Non-polar magnetic nanoparticles agglomerate upon cooling. This process is\nfollowed by in-situ small angle X-ray scattering to assess structural\nproperties of the emerging agglomerates. On the length scale of a few particle\ndiameters, no differences are found between the agglomerates of small (d =\n12nm) and large (d = 22nm) nanoparticles. Hard-sphere like random packing with\na local packing fraction of $\\eta$ = 0.4 is seen. On larger length scales,\nsmall particle form compact superstructures, while large particles arrange into\nagglomerates that resemble chain-like structure in SAXS. This can be explained\nby directed magnetic dipole interactions that dominate larger particles, while\nisotropic van der Waals interaction governs the agglomeration of smaller\nparticles.",
        "positive": "Constant Pressure Hybrid Molecular Dynamics-Monte Carlo Simulations: New hybrid Molecular Dynamics-Monte Carlo methods are proposed to increase\nthe efficiency of constant-pressure simulations. Two variations of the isobaric\nMolecular Dynamics component of the algorithms are considered. In the first, we\nuse the extended-ensemble method of Andersen [H. C. Andersen J. Chem. Phys.\n{\\bf 72},2384 (1980)]. In the second, we arrive at a new constant-pressure\nMonte Carlo technique based on the reversible generalization of the\nweak-coupling barostat [H. J. C. Berendsen et. al J. Chem. Phys. {\\bf 81},\n3684(1984)]. This latter technique turns out to be highly effective in\nequilibrating and maintaining a target pressure. It is superior to the\nextended-ensemble method, which in turn is superior to simple volume-rescaling\nalgorithms. The efficiency of the proposed methods is demonstrated by studying\ntwo systems. The first is a simple Lennard-Jones fluid. The second is a mixture\nof polyethylene chains of 200 monomers."
    },
    {
        "anchor": "Extreme cavity expansion in soft solids: damage without fracture: Cavitation is a common damage mechanism in soft solids. Here, we study this\nusing a phase-separation technique in stretched, elastic solids to controllably\nnucleate and grow small cavities by several orders of magnitude. The ability to\nmake stable cavities of different sizes, as well as the huge range of\naccessible strains, allows us to systematically study the early stages of\ncavity expansion. Cavities grow in a scale-free manner, accompanied by\nirreversible bond breakage that is distributed around the growing cavity,\nrather than being localized to a crack tip. Furthermore, cavities appear to\ngrow at constant driving pressure. This has strong analogies with the\nplasticity that occurs surrounding a growing void in ductile metals. In\nparticular we find that, although elastomers are normally considered as brittle\nmaterials, small-scale cavity expansion is more like a ductile process. Our\nresults have broad implications for understanding and controlling failure in\nsoft solids.",
        "positive": "Electrokinetic Effects in Catalytic Pt-Insulator Janus Swimmers: The effect of added salt on the propulsion of Janus platinum-polystyrene\ncolloids in hydrogen peroxide solution is studied experimentally. It is found\nthat micromolar quantities of potassium and silver nitrate salts reduce the\nswimming velocity by similar amounts, while leading to significantly different\neffects on the overall rate of catalytic breakdown of hydrogen peroxide. It is\nargued that the seemingly paradoxical experimental observations could be\ntheoretically explained by using a generalised reaction scheme that involves\ncharged intermediates and has the topology of two nested loops."
    },
    {
        "anchor": "Extending and validating bubble nucleation rate predictions in a\n  Lennard-Jones fluid with enhanced sampling methods and transition state\n  theory: We calculate bubble nucleation rates in a Lennard-Jones fluid through\nexplicit molecular dynamics simulations. Our approach -- based on a recent free\nenergy method (dubbed reweighted Jarzynski sampling), transition state theory,\nand a simple recrossing correction -- allows us to probe a fairly wide range of\nrates in several superheated and cavitation regimes in a consistent manner.\nRate predictions from this approach bridge disparate independent literature\nstudies on the same model system. As such, we find that rate predictions based\non classical nucleation theory, direct brute force molecular dynamics\nsimulations, and seeding are consistent with our approach and one another.\nPublished rates derived from forward flux sampling simulations are, however,\nfound to be outliers. This study serves two purposes. First, we validate the\nreliability of common modeling techniques and extrapolation approaches on a\nparadigmatic problem in materials science and chemical physics. Second, we\nfurther test our highly generic recipe for rate calculations, and establish its\napplicability to nucleation processes.",
        "positive": "Collective excitations of a trapped Bose-Einstein condensate in the\n  presence of a 1D optical lattice: We study low-lying collective modes of a horizontally elongated 87Rb\ncondensate produced in a 3D magnetic harmonic trap with the addition of a 1D\nperiodic potential which is provided by a laser standing-wave along the\nhorizontal axis. While the transverse breathing mode results unperturbed,\nquadrupole and dipole oscillations along the optical lattice are strongly\nmodified. Precise measurements of the collective mode frequencies at different\nheight of the optical barriers provide a stringent test of the theoretical\nmodel recently introduced [M.Kraemer et al. Phys. Rev. Lett. 88 180404 (2002)]."
    },
    {
        "anchor": "Coating thickness and coverage effects on the forces between silica\n  nanoparticles in water: The structure and interactions of coated silica nanoparticles have been\nstudied in water using molecular dynamics simulations. For 5 nm diameter\namorphous silica nanoparticles we studied the effects of varying the chain\nlength and grafting density of polyethylene oxide (PEO) on the nanoparticle\ncoating's shape and on nanoparticle-nanoparticle effective forces. For short\nligands of length $n=6$ and $n=20$ repeat units, the coatings are radially\nsymmetric while for longer chains ($n=100$) the coatings are highly\nanisotropic. This anisotropy appears to be governed primarily by chain length,\nwith coverage playing a secondary role. For the largest chain lengths\nconsidered, the strongly anisotropic shape makes fitting to a simple radial\nforce model impossible. For shorter ligands, where the coatings are isotropic,\nwe found that the force between pairs of nanoparticles is purely repulsive and\ncan be fit to the form $(R/2r_\\text{core}-1)^{-b}$ where $R$ is the separation\nbetween the center of the nanoparticles, $r_\\text{core}$ is the radius of the\nsilica core, and $b$ is measured to be between 2.3 and 4.1.",
        "positive": "Actin based propulsion: Intriguing interplay between material properties\n  and growth processes: Eukaryotic cells and intracellular pathogens such as bacteria or viruses\nutilize the actin polymerization machinery to propel themselves forward.\nThereby, the onset of motion and choice of direction may be the result of a\nspontaneous symmetry-breaking or might be triggered by external signals and\npreexisting asymmetries, e.g. through a previous septation in bacteria.\nAlthough very complex, a key feature of cellular motility is the ability of\nactin to form dense polymeric networks, whose microstructure is tightly\nregulated by the cell. These polar actin networks produce the forces necessary\nfor propulsion but may also be at the origin of a spontaneous\nsymmetry-breaking. Understanding the exact role of actin dynamics in cell\nmotility requires multiscale approaches which capture at the same time the\npolymer network structure and dynamics on the scale of a few nanometers and the\nmacroscopic distribution of elastic stresses on the scale of the whole cell. In\nthis chapter we review a selection of theories on how mechanical material\nproperties and growth processes interact to induce the onset of actin based\nmotion."
    },
    {
        "anchor": "From a distance: Shuttleworth revisited: The Shuttleworth equation: a linear stress-strain relation ubiquitously used\nin modeling the behavior of soft surfaces. Its validity in the realm of\nmaterials subject to large deformation is a topic of current debate. Here, we\nzoom out to derive the constitutive behavior of the surface from the general\nframework of finite kinematics. We distinguish cases of finite and\ninfinitesimal surface relaxation prior to an infinitesimal applied deformation.\nThe Shuttleworth equation identifies as the Cauchy stress measure in the fully\nlinearized setting. We show that in both finite and linearized cases, measured\nelastic constants depend on the utilized stress measure. In addition, we\ndiscuss the physical implications of our results and analyze the magnitude of\nsurface relaxation in the light of two different test cases.",
        "positive": "Jamming at zero temperature, zero friction, and finite applied shear\n  stress: Via molecular dynamics simulations, we unveil the hysteretic nature of the\njamming transition of soft repulsive frictionless spheres, as it occurs varying\nthe volume fraction or the shear stress. In a given range of control parameters\nthe system may be found both in a flowing and in an jammed state, depending on\nthe preparation protocol. The hysteresis is due to an underlying energy\nlandscape with many minima, as explained by a simple model, and disappears in\nthe presence of strong viscous forces and in the small $\\sigma$ limit. In this\nlimit, structural quantities are continuous at the transition, while the\nasymptotic values of two time quantities such as the self-intermediate\nscattering function are discontinuous, giving to the jamming transition a mixed\nfirst-order second-order character close to that found at the glass transition\nof thermal systems."
    },
    {
        "anchor": "Transformable Super-Isostatic Crystals Self-Assembled from Segment\n  Colloidal Rods: Colloidal particles can spontaneously self-assemble into ordered structures,\nwhich not only can manipulate the propagation of light, but also vibration or\nphonons. Using Monte Carlo simulation, we study the self-assembly of perfectly\naligned segment rod particles with lateral flat cutting. Under the help of\nsurface attractions, we find that particles with different cutting degree can\nself-assemble into different crystal phases characterized by bond coordination\nz that varies from 3 to 6. Importantly, we identify a transformable\nsuper-isostatic structures with pgg symmetry and redundant bonds (z=5). We find\nthat this structure can support either the soft bulk model or soft edge model\ndepending on its Poisson's ratio which can be tuned from positive to negative\nby a uniform soft deformation. Importantly, the bulk soft modes are associated\nwith states of self-stress along the direction of zero strain during the\nuniform soft deformation. This self-assembled transformable super-isostatic\nstructure may act as mechanical metamaterials with potential application in\nmicro-mechanical engineering.",
        "positive": "Criticality and isostaticity in fiber networks: The rigidity of elastic networks depends sensitively on their internal\nconnectivity and the nature of the interactions between constituents. Particles\ninteracting via central forces undergo a zero-temperature rigidity-percolation\ntransition near the isostatic threshold, where the constraints and internal\ndegrees of freedom are equal in number. Fibrous networks, such as those that\nform the cellular cytoskeleton, become rigid at a lower threshold due to\nadditional bending constraints. However, the degree to which bending governs\nnetwork mechanics remains a subject of considerable debate. We study disordered\nfibrous networks with variable coordination number, both above and below the\ncentral-force isostatic point. This point controls a broad crossover from\nstretching- to bending-dominated elasticity. Strikingly, this crossover\nexhibits an anomalous power-law dependence of the shear modulus on both\nstretching and bending rigidities. At the central-force isostatic point---well\nabove the rigidity threshold---we find divergent strain fluctuations together\nwith a divergent correlation length $\\xi$, implying a breakdown of continuum\nelasticity in this simple mechanical system on length scales less than $\\xi$."
    },
    {
        "anchor": "Pattern Formation in Chemically Interacting Active Rotors with\n  Self-Propulsion: We demonstrate that active rotations in chemically signalling particles, such\nas autochemotactic {\\it E. coli} close to walls, create a route for pattern\nformation based on a nonlinear yet deterministic instability mechanism. For\nslow rotations, we find a transient persistence of the uniform state, followed\nby a sudden formation of clusters contingent on locking of the average\npropulsion direction by chemotaxis. These clusters coarsen, which results in\nphase separation into a dense and a dilute region. Faster rotations arrest\nphase separation leading to a global travelling wave of rotors with\nsynchronized roto-translational motion. Our results elucidate the physics\nresulting from the competition of two generic paradigms in active matter,\nchemotaxis and active rotations, and show that the latter provides a tool to\ndesign programmable self-assembly of active matter, for example to control\ncoarsening.",
        "positive": "Semi-flexible chain condensation by neutral depleting agents: role of\n  correlations between depletants: We revisit the problem of semi-flexible chain condensation by neutral\ndepleting agents (e.g. colloidal spheres or flexible polymers) by using a\nsimple formalism that allows us to address its main features without specifying\nthe kind of depleting agents. Correlations between depleting agents are shown\nto produce a reswelling of the chain at high enough volume fraction, consistent\nwith an earlier analysis by Grosberg et al. (Biopolymers, 21:2413, 1982) in the\ncontext of DNA condensation induced by neutral polymers. It is also shown that\nthe conditions under which spherical colloids can condense a semi-flexible\nchain are strongly restrictive, unlike what has been recently claimed. The\nformalism allows us to compare the efficiency of colloids vs polymers as\ncondensing agents."
    },
    {
        "anchor": "Deformation propagation in responsive polymer network films: We study the elastic deformations in a cross-linked polymer network film\ntriggered by the binding of submicron particles with a sticky surface,\nmimicking the interactions of viral pathogens with thin films of\nstimulus-responsive polymeric materials such as hydrogels. From extensive\nLangevin Dynamics simulations we quantify how far the network deformations\npropagate depending on the elasticity parameters of the network and the\nadhesion strength of the particles. We examine the dynamics of the collective\narea shrinkage of the network and obtain some simple relations for the\nassociated characteristic decay lengths. A detailed analysis elucidates how the\nelastic energy of the network is distributed between stretching and compression\nmodes in response to the particle binding. We also examine the force-distance\ncurves of the repulsion or attraction interactions for a pair of sticky\nparticles in the polymer network film as a function of the particle-particle\nseparation. The results of this computational study provide new insight into\ncollective phenomena in soft polymer network films and may, in particular, be\napplied to applications for visual detection of pathogens such as viruses via a\nmacroscopic response of thin films of cross-linked hydrogels.",
        "positive": "$K$-core analysis of shear-thickening suspensions: Shear thickening of suspensions is studied by discrete-particle simulation,\naccounting for hydrodynamic, repulsive, and contact forces. The contact forces,\nincluding friction, are activated when the imposed shear stress $\\sigma$ is\nable to overcome the repulsive force. The simulation method captures strong\ncontinuous and discontinuous shear thickening (CST and DST) in the range of\nsolid volume fraction $0.54 \\le \\phi\\le 0.56$ studied here. This work presents\ncharacteristics of the contact force network developed in the suspension under\nshear. The number of frictional contacts per particle $Z$ is shown to have a\none-to-one relationship with the suspension stress, and the conditions for\nsimple percolation of frictional contacts are found to deviate strongly from\nthose of a random network model. The stress is shown to have important\ncorrelations with topological invariant metrics of the contact network known as\n$k$-cores; the $k$-cores are maximal subgraphs (`clusters') in which all member\nparticles have $k$ or more frictional contacts to other members of the same\nsubgraph. Only $k\\le 3$ is found in this work at solid volume fractions $\\phi\n\\le 0.56$. Distinct relationships between the suspension rheology and the\n$k$-cores are found. One is that the stress susceptibility, defined as\n$\\partial \\sigma/\\partial \\dot{\\gamma}$ where $\\dot{\\gamma}$ is the shear rate,\nis found to peak at the condition of onset of the $3$-core, regardless of\nwhether the system exhibits CST or DST. A second is that the stress per\nparticle within cores of different $k$ increases sharply with increase of $k$\nat the onset of DST; in CST, the difference is mild."
    },
    {
        "anchor": "The jamming transition is a k-core percolation transition: We explain the structural origin of the jamming transition in jammed matter\nas the sudden appearance of k-cores at precise coordination numbers which are\nrelated not to the isostatic point, but to the sudden emergence of the 3- and\n4-cores as given by k-core percolation theory. At the transition, the k-core\nvariables freeze and the k-core dominates the appearance of rigidity.\nSurprisingly, the 3-D simulation results can be explained with the result of\nmean-field k-core percolation in the Erdos-Renyi network. That is, the\nfinite-dimensional transition seems to be explained by the infinite-dimensional\nk-core, implying that the structure of the jammed pack is compatible with a\nfully random network.",
        "positive": "Microscopic Wrinkles on Supported Surfactant Monolayers: We discuss mechanical buckling instabilities of a rigid film under\ncompression interacting repulsively with a substrate through a thin fluid\nlayer. The buckling occurs at a characteristic wavelength that increases as the\n1/4th power of the bending stiffness, like a gravitational instability studied\npreviously by Milner et al. However, the potential can affect the\ncharacteristic buckling wavelength strongly, as predicted by Huang and Suo. If\nthe potential changes sufficiently sharply with thickness, this instability is\ncontinuous, with an amplitude varying as the square root of overpressure. We\ndiscuss three forms of interaction important for the case of Langmuir\nmonolayers transferred to a substrate: Casimir-van der Waals interaction,\nscreened charged double-layer interaction and the Sharma potential. We verify\nthese predictions numerically in the Van der Waals case."
    },
    {
        "anchor": "Critical velocity in cylindrical Bose-Einstein condensates: We describe a dramatic decrease of the critical velocity in elongated\ncylindrical Bose-Einstein condensates which originates from the non-uniform\ncharacter of the radial density profile. We discuss this mechanism with respect\nto recent measurements at MIT.",
        "positive": "Pressure-energy correlations in liquids. III. Statistical mechanics and\n  thermodynamics of liquids with hidden scale invariance: In this third paper of the series, which started with [N. P. Bailey et al.,\nJ. Chem. Phys. 129, 184507 and 184508 (2008)], we continue the development of\nthe theoretical understanding of strongly correlating liquids - those whose\ninstantaneous potential energy and virial are strongly correlated in their\nthermal equilibrium fluctuations at constant volume. The existence of such\nliquids was detailed in previous work which identified them, based on computer\nsimulations, as a large class of liquids, including van der Waals liquids but\nnot, e.g., hydrogen-bonded liquids. We here discuss the following: (1) The\nscaling properties of inverse power-law and extended inverse power-law\npotentials (the latter include a linear term which \"hides\" the approximate\nscale invariance); (2) results from computer simulations of molecular models\nconcerning out-of-equilibrium conditions; (3) ensemble dependence of the virial\n/ potential energy correlation coefficient; (4) connection to the Gruneisen\nparameter; (5) interpretation of strong correlations in terms of the\nenergy-bond formalism."
    },
    {
        "anchor": "Humidity-insensitive water evaporation from molecular complex fluids: We investigated theoretically water evaporation from concentrated\nsupramolecular mixtures, such as solutions of polymers or amphiphilic\nmolecules, using numerical resolutions of a one dimensional model based on mass\ntransport equations. Solvent evaporation leads to the formation of a\nconcentrated solute layer at the drying interface, which slows down evaporation\nin a long-time scale regime. In this regime, often referred to as the falling\nrate period, evaporation is dominated by diffusive mass transport within the\nsolution, as already known. However, we demonstrate that, in this regime, the\nrate of evaporation does not also depend on the ambient humidity for many\nmolecular complex fluids. Using analytical solutions in some limiting cases, we\nfirst demonstrate that a sharp decrease of the water chemical activity at high\nsolute concentration, leads to evaporation rates which depend weakly on the\nhumidity, as the solute concentration at the drying interface slightly depends\non the humidity. However, we also show that a strong decrease of the mutual\ndiffusion coefficient of the solution enhances considerably this effect,\nleading to nearly independent evaporation rates over a wide range of humidity.\nThe decrease of the mutual diffusion coefficient indeed induces strong\nconcentration gradients at the drying interface, which shield the concentration\nprofiles from humidity variations, except in a very thin region close to the\ndrying interface.",
        "positive": "The contribution of Brownian motion to the stress in a colloidal\n  suspension: The deviatoric stresses of colloidal suspensions are routinely calculated\nusing the expression introduced by Batchelor [J. Fluid Mech. 83, 97--117\n(1977)]. We show by example that the central feature in its derivation, the\nthermodynamic force driving particles down the density gradient, is\ninconsistent with the motion of the colloids. A new expression for the stress\nis proposed."
    },
    {
        "anchor": "Condensed phases of gases inside nanotube bundles: An overview is presented of the various phases predicted to occur when gases\nare absorbed within a bundle of carbon nanotubes. The behavior may be\ncharacterized by an effective dimensionality, which depends on the species and\nthe temperature. Small molecules are strongly attracted to the interstitial\nchannels between tubes. There, they undergo transitions between ordered and\ndisordered quasi-one dimensional (1D) phases. Both small and large molecules\ndisplay 1D and /or 2D phase behavior when adsorbed within the nanotubes,\ndepending on the species and thermodynamic conditions. Finally, molecules\nadsorbed on the external surface of the bundle exhibit 1D behavior (striped\nphases), which crosses over to 2D behavior (monolayer film) and eventually 3D\nbehavior (thick film) as the coverage is increased. The various phases exhibit\na wide variety of thermal and other properties that we discuss here.",
        "positive": "Phase Diagram for Ultracold Bosons in Optical Lattices and Superlattices: We present an analytic description of the finite-temperature phase diagram of\nthe Bose-Hubbard model, successfully describing the physics of cold bosonic\natoms trapped in optical lattices and superlattices. Based on a standard\nstatistical mechanics approach, we provide the exact expression for the\nboundary between the superfluid and the normal fluid by solving the\nself-consistency equations involved in the mean-field approximation to the\nBose-Hubbard model. The zero-temperature limit of such result supplies an\nanalytic expression for the Mott lobes of superlattices, characterized by a\ncritical fractional filling."
    },
    {
        "anchor": "The Role of Chemical Heterogeneity in Surfactant Adsorption at\n  Solid-Liquid Interfaces: Chemical heterogeneity of solid surfaces disrupts the adsorption of\nsurfactants from the bulk liquid. While its presence can hinder the performance\nof some formulations, bespoke chemical patterning could potentially facilitate\ncontrolled adsorption for nanolithography applications. Although some\ncomputational studies have investigated the impact of regularly patterned\nsurfaces on surfactant adsorption, in reality many interesting surfaces are\nexpected to be stochastically disordered and this is an area unexplored via\nsimulations. In this paper we describe a new algorithm for the generation of\nrandomly disordered chemically heterogeneous surfaces and use it to explore the\nadsorption behaviour of four model nonionic surfactants. Using novel analysis\nmethods we interrogate both the global surface coverage (adsorption isotherm)\nand behaviour in localised regions. We observe trends in adsorption\ncharacteristics as surfactant size, head/tail ratio, and surface topology are\nvaried and connect these to underlying physical mechanisms. We believe that our\nmethods and approach will prove useful to researchers seeking to tailor surface\npatterns to calibrate nonionic surfactant adsorption.",
        "positive": "Compression and fracture of ordered and disordered droplet rafts: We simulate a two-dimensional array of droplets being compressed between two\nwalls. The droplets are adhesive due to an attractive depletion force. As one\nwall moves toward the other, the droplet array is compressed and eventually\ninduced to rearrange. The rearrangement occurs via a fracture, where depletion\nbonds are quickly broken between a subset of droplets. For monodisperse,\nhexagonally ordered droplet arrays, this fracture is preceded by a maximum\nforce exerted on the walls, which drops rapidly after the fracture occurs. In\nsmall droplet arrays a fracture is a single well-defined event, but for larger\ndroplet arrays, competing fractures can be observed. These are fractures\nnucleated nearly simultaneously in different locations. Finally, we also study\nthe compression of bidisperse droplet arrays. The addition of a second droplet\nsize further disrupts fracture events, showing differences between ideal\ncrystalline arrays, crystalline arrays with a small number of defects, and\nfully amorphous arrays. These results are in good agreement with previously\npublished experiments."
    },
    {
        "anchor": "Effect of Collisional Elasticity on the Bagnold Rheology of Sheared\n  Frictionless Two Dimensional Disks: We carry out constant volume simulations of steady-state, shear driven flow\nin a simple model of athermal, bidisperse, soft-core, frictionless disks in two\ndimensions, using a dissipation law that gives rise to Bagnoldian rheology.\nFocusing on the small strain rate limit, we map out the rheological behavior as\na function of particle packing fraction $\\phi$ and a parameter $Q$ that\nmeasures the elasticity of binary particle collisions. We find a $Q^*(\\phi)$\nthat marks the clear crossover from a region characteristic of strongly\ninelastic collisions, $Q<Q^*$, to a region characteristic of weakly inelastic\ncollisions, $Q>Q^*$, and give evidence that $Q^*(\\phi)$ diverges as\n$\\phi\\to\\phi_J$, the shear driven jamming transition. We thus conclude that the\njamming transition at any value of $Q$ behaves the same as the strongly\ninelastic case, provide one is sufficiently close to $\\phi_J$. We further\ncharacterize the differing nature of collisions in the strongly inelastic vs\nweakly inelastic regions, and recast our results into the constituent equation\nform commonly used in discussions of hard granular matter.",
        "positive": "Extracting short-ranged interactions from structure factors: Inverting scattering experiments to obtain effective interparticle\ninteractions is generally a poorly conditioned problem. L. Reatto (Phil. Mag. A\n58, 37 (1986)) showed that for atomic liquids close to the triple point,\ninversions are hard because the structure closely resembles that of an\nequivalent hard-sphere fluid. Here I demonstrate that at low concentrations and\nfor particles with short-ranged attractive potentials, S(k) also exhibits a\nvery weak dependence on potential shape. Instead, different potentials can\ngenerate an S(k) that closely resembles that of the Baxter model with a similar\nsecond-virial coefficient. By contrast, in this energetic fluid regime, the\ninversion of an attractive interaction from real-space correlations such as the\nradial distribution function g(r) is well conditioned. Nevertheless, one may\nextract further information from S(k) by measuring isosbestic points, values of\nk where the scattering intensity I(k) or the structure factor S(k) is invariant\nto changes in interaction-potential well-depth. These points suggest a new\nextended corresponding states principle for particles in solution based on the\npacking fraction, the second osmotic virial coefficient, and a new measure of\neffective potential range."
    },
    {
        "anchor": "Manipulating P-and S-elastic waves in dielectric elastomers via external\n  electric stimuli: We investigate elastic wave propagation in finitely deformed dielectric\nelastomers in the presence of an electrostatic field. To analyze the\npropagation of both longitudinal (P-) and transverse (S-) waves, we utilize\ncompressible material models. We derive explicit expressions of the generalized\nacoustic tensor and phase velocities of elastic waves for the ideal and\nenriched dielectric elastomer models. We analyze the slowness curves of the\nelastic wave propagation, and find the P-S-mode disentangling phenomenon. In\nparticular, P- and S- waves are separated by the application of an electric\nfield. The divergence angle between P- and S-waves strongly depends on the\napplied electrostatic excitation. The influence of the electric field is\nsensitive to material models. Thus, for ideal dielectric model the in-plane\nshear velocity increases with an increase in electric field, while for the\nenriched model the velocity may decreases depending on material constants.\nSimilarly, the divergence angle gradually increases with an increase in\nelectric field, while for the enriched model, the angle may be bounded.\nMaterial compressibility affects the P-wave velocity, and, for relatively\ncompressible materials, the slowness curves evolve from circular to elliptical\nshapes manifesting in an increase of the reflection angle of P-waves. As a\nresults, the divergence angle decreases with an increase in material\ncompressibility.",
        "positive": "Superscreening and polarization control in confined ferroelectric\n  nematic liquids: The combination of large spontaneous polarization and fluidity makes the\nnewly discovered ferroelectric nematic liquid crystalline phase (NF) responsive\nto electric fields in ways that have no counterpart in other materials. We\nprobe this sensitive field response by confining a NF fluid in microchannels\nthat connect electrodes through straight and curved paths. We find that by\napplying electric fields as low as E c.a. 0.5 V/mm, the NF phase orders with\nits polarization smoothly following the winding paths of the channels even when\noriented antiparallel to the line connecting positive to negative electrodes,\nimplying analogous behavior of the electric field. Upon inversion of E, the\npolar order undergoes a complex multistage switching process dominated by\nelectrostatic interactions. Multistage polarization switching dynamics is also\nfound in numerical simulations of a quasi-2D continuum model of NF liquid\ncrystals in microchannels, which also clarify the conditions under which the\nelectric field is guided by the microchannels. Experiments and theory indicate\nthat all observations are direct consequences of the prompt effective screening\nof electric field components normal to the channel walls. This electric\n\"superscreening\" effect emerges as a distinctive property of the NF phase,\ncapable of inducing conditions in which both the polarization and the electric\nfield are guided by microchannels."
    },
    {
        "anchor": "Geometrical families of mechanically stable granular packings: We enumerate and classify nearly all of the possible mechanically stable (MS)\npackings of bidipserse mixtures of frictionless disks in small sheared systems.\nWe find that MS packings form continuous geometrical families, where each\nfamily is defined by its particular network of particle contacts. We also\nmonitor the dynamics of MS packings along geometrical families by applying\nquasistatic simple shear strain at zero pressure. For small numbers of\nparticles (N < 16), we find that the dynamics is deterministic and highly\ncontracting. That is, if the system is initialized in a MS packing at a given\nshear strain, it will quickly lock into a periodic orbit at subsequent shear\nstrain, and therefore sample only a very small fraction of the possible MS\npackings in steady state. In studies with N>16, we observe an increase in the\nperiod and random splittings of the trajectories caused by bifurcations in\nconfiguration space. We argue that the ratio of the splitting and contraction\nrates in large systems will determine the distribution of MS-packing\ngeometrical families visited in steady-state. This work is part of our\nlong-term research program to develop a master-equation formalism to describe\nmacroscopic slowly driven granular systems in terms of collections of small\nsubsystems.",
        "positive": "On the spectrum of fluctuations of a liquid surface: From the molecular\n  scale to the macroscopic scale: We show that to account for the full spectrum of surface fluctuations from\nlow scattering vector qd << 1 (classical capillary wave theory) to high qd > 1\n(bulk-like fluctuations), one must take account of the interface's bending\nrigidity at intermediate scattering vector qd = 1, where d is the molecular\ndiameter. A molecular model is presented to describe the bending correction to\nthe capillary wave model for short-ranged and long-ranged interactions between\nmolecules. We find that the bending rigidity is negative when the Gibbs\nequimolar surface is used to define the location of the fluctuating interface\nand that on approach to the critical point it vanishes proportionally to the\ninterfacial tension. Both features are in agreement with Monte Carlo\nsimulations of a phase-separated colloid-polymer system."
    },
    {
        "anchor": "On the problem of phase transitions in lysozyme crystals: We present experimental evidence of the fact that lysozyme crystals, which\nare grown from their mother solution and exist in it, dissolve on heating above\nT=307 K. We argue that the anomaly in the light scattering recently observed at\nthe temperature T=307 K and identified in the reference [Svanidze A. V. et al.\n2006. JETP Lett. 84: 551] as a structural crystalline phase transition in the\nsingle lysozyme crystals, in fact, corresponds to a temperature limit of the\ncrystal existence.",
        "positive": "Elimination of Interionic Hydrogen Bonding in the Imidazolium-Based\n  Ionic Liquids: Hydrogen bonding is a phenomenon of paramount importance in room-temperature\nionic liquids. The presence or absence of the hydrogen bond drastically\nalternates self-diffusion, shear viscosity, phase transition points, and other\nkey properties of a pure substance. For certain applications, the presence of\ncation-anion hydrogen bonding is undesirable. In the present paper, we\ninvestigate perspectives of removing the hydrogen...fluorine interionic\nattraction in the imidazolium borates, the strongest non-covalent interaction\nin this type of system. Chemical modification of the tetrafluoroborate anion\nnot only eliminates hydrogen bonding but also changes the most\nthermodynamically preferable orientation of the cation in the vicinity of the\nanion. Although the most acidic hydrogen atom of the imidazole ring remains the\nparamount electrophilic center of the cation, it does not engender a strong\nelectrostatically driven coordination pattern with the properly modified\nanions. The reported new physical insights help compose more robust ionic\nliquids and tune solvation properties of the imidazolium-based RTILs."
    },
    {
        "anchor": "Frustrated bearings: In a bearing state, touching spheres (disks in two dimensions) roll on each\nother without slip. Here we frustrate a system of touching spheres by imposing\ntwo different bearing states on opposite sides and search for the\nconfigurations of lowest energy dissipation. If the dissipation between\ncontacts of spheres is viscous (with random damping constants), the angular\nmomentum continuously changes from one bearing state to the other. For Coulomb\nfriction (with random friction coefficients) in two dimensions, a sharp line\nseparates the two bearing states and we show that this line corresponds to the\nminimum cut. Astonishingly however, in three dimensions, intermediate bearing\ndomains, that are not synchronized with either side, are energetically more\nfavorable than the minimum-cut surface. Instead of a sharp cut, the steady\nstate displays a fragmented structure. This novel type of state of minimum\ndissipation is characterized by a spanning network of slipless contacts that\nreaches every sphere. Such a situation becomes possible because in three\ndimensions bearing states have four degrees of freedom.",
        "positive": "Multispeckle diffusing wave spectroscopy as a tool to study\n  heterogeneous mechanical behavior in soft solids: Multiple speckle diffusing wave spectroscopy (MSDWS) can be applied to\nmeasure spatially heterogeneous mechanical behavior in soft solids, with high\nsensitivity to deformation and both spatial and temporal resolution. In this\npaper, we discuss the mathematical approach behind the quantification of the\ndeformation rate from MSDWS data and provide guidelines for optimizing the\nselection of experimental parameters in measurements. After validating the\nmethod in extensional tests on an elastomer, we provide an example of the\npotentiality of MSDWS by measuring the spatial distribution of the deformation\nrate during shear debonding of adhesive tapes. We quantitatively characterize\nthe deformation rate distribution related to shearing and peeling under\nloading. A highly heterogeneous deformation rate distribution is observed, and\ntime-dependent measurements reveal an increase in deformation localization\nhundreds of seconds before full debonding. This behavior, previously predicted\nby theory and simulation, is here demonstrated experimentally for the first\ntime."
    },
    {
        "anchor": "Collective Transport of Lennard-Jones Particles through One-Dimensional\n  Periodic Potentials: Transport surrounding is full of all kinds of fields, like particle\npotential, external potential. Under these conditions, how elements work and\nhow position and momentum redistribute in the diffusion? For enriching the Fick\nlaw in ordinary, nonequilibrium statistics physics need to be used to\ndisintegrate the complex process. This study attempts to discuss the particle\ntransport in the one-dimensional channel under external potential fields. Two\ntype of potentials, potential well and barrier do not change the potential in\ntotal, are built during the diffusion process. There are quite distinct\nphenomena because of different one-dimensional periodic potentials. We\nmeticulously explore reasons about why external potential field impacts\ntransport by the subsection and statistics method. Besides, one of the\nevidences of Maxwell velocity distribution is confirmed in assumption of local\nequilibrium. In addition, we have also investigated the influence of\ntemperature and concentration to the collective diffusion coefficient, by a\nvariety of external force, attaching thermodynamics analyze to these opposite\nphenomena. So simply is this model that the most valuable point may be an idea,\nwhich relating flux to sectional statistics of position and momentum could be\nreferenced in similar transport problems.",
        "positive": "Thermal Fluctuations of Elastic Filaments with Spontaneous Curvature and\n  Torsion: We study the effects of thermal flucutations on thin elastic filaments with\nspontaneous curvature and torsion. We derive analytical expressions for the\norientational correlation functions and for the persistence length of helices,\nand find that this length varies non-monotonically with the strength of thermal\nfluctuations. In the weak fluctuation regime, the persistence length of a\nspontaneously twisted helix has three resonance peaks as a function of the\ntwist rate. In the limit of strong fluctuations, all memory of the helical\nshape is lost."
    },
    {
        "anchor": "Bivalent defect configurations in inhomogeneous nematic shells: We present a theoretical study of the director fields and energetics of\nnematic liquid crystal shells with two pairs of surface defects. The pairs of\ndefects can undergo abrupt transitions between a configuration of maximum\nseparation to at state in which the defects are confined to the thinnest\nhemisphere. We construct a phase diagram that maps out the stability and\ncoexistence of these two configurations as a function of shell thickness and\nthickness inhomogeneity. Our results compare favorably with the experimentally\nobserved transitions in nematic double emulsion droplets and explain their\nhysteretic character.",
        "positive": "Interfacial Instability of Charged End-Group Polymer Brushes: We consider a polymer brush grafted to a surface (acting as an electrode) and\nbearing a charged group at its free end. Using a second distant electrode, the\nbrush is subject to a constant electric field. Based on a coarse-grained\ncontinuum model, we calculate the average brush height and find that the brush\ncan stretch or compress depending on the applied field and charge end-group. We\nfurther look at an undulation mode of the flat polymer brush and find that the\nelectrostatic energy scales linearly with the undulation wavenumber, $q$.\nCompetition with surface tension, scaling as $q^2$, tends to stabilize a\nlateral $q$-mode of the polymer brush with a well-defined wavelength. This\nwavelength depends on the brush height, surface separation, and several system\nparameters."
    },
    {
        "anchor": "Topological transitions in the configuration space of non-Euclidean\n  origami: Origami structures have been proposed as a means of creating\nthree-dimensional structures from the micro- to the macroscale, and as a means\nof fabricating mechanical metamaterials. The design of such structures requires\na deep understanding of the kinematics of origami fold patterns. Here, we study\nthe configurations of non-Euclidean origami, folding structures with Gaussian\ncurvature concentrated on the vertices. The kinematics of such structures\ndepends crucially on the sign of the Gaussian curvature. The configuration\nspace of non-intersecting, oriented vertices with positive Gaussian curvature\ndecomposes into disconnected subspaces; there is no pathway between them\nwithout tearing the origami. In contrast, the configuration space of negative\nGaussian curvature vertices remain connected. This provides a new mechanism by\nwhich the mechanics and folding of an origami structure could be controlled.",
        "positive": "Heuristic rule for binary superlattice coassembly: Mixed plastic\n  mesophases of hard polyhedral nanoparticles: Sought-after ordered structures of mixtures of hard anisotropic nanoparticles\ncan often be thermodynamically unfavorable due to the components' geometric\nincompatibility to densely pack into regular lattices. A simple\ncompatibilization rule is identified wherein the particle sizes are chosen such\nthat the order-disorder transition pressures of the pure components match (and\nthe entropies of the ordered phases are similar). Using this rule with\nrepresentative polyhedra from the truncated-cube family that form\npure-component plastic-crystals, Monte Carlo simulations show the formation of\nplastic-solid solutions for all compositions and for a wide range of volume\nfractions."
    },
    {
        "anchor": "Nanomechanical resonance captures pre-melting transition in DNA\n  unravelling: A double-stranded DNA unravels thermally through intermediate denatured\nbubble segments. Intrinsically, fluctuations ensue at the bubble boundaries\nfrom non-equilibrium (NE) energy exchanges with the environment. However, such\ndetails gets obscured by large population kinetics at the macroscale,\nassociating equilibrium pathway to the unravelling landscape. In this work, we\ncapture evidence of fluctuation energetics with picoliter samples in a\nmicrofluidic cantilever. We exploit nanomechanical resonance to measure the NE\nenergy exchanges through dissipation, revealing a crucial pre-melting\ntransition at T~42C . This signifies that unravelling possibly proceeds via\nintermediate collapsed-bubble conformations releasing energy, sufficient to\nunbind bubble ends, assisting further unbinding. Fluctuation theorem explains\nthe observations opening further avenues to investigate fluctuation kinetics in\nother biological phenomena that also proceed through similar NE energetics.",
        "positive": "Swarming in viscous fluids: three-dimensional patterns in swimmer- and\n  force-induced flows: We derive from first principles a three-dimensional theory of self-propelled\nparticle swarming in a viscous fluid environment. Our model predicts emergent\ncollective behavior that depends critically on fluid opacity, mechanism of\nself-propulsion, and type of particle-particle interaction. In \"clear fluids\"\nswimmers have full knowledge of their surroundings and can adjust their\nvelocities with respect to the lab frame, while in \"opaque fluids,\" they\ncontrol their velocities only in relation to the local fluid flow. We also show\nthat \"social\" interactions that affect only a particle's propensity to swim\ntowards or away from neighbors induces a flow field that is qualitatively\ndifferent from the long-ranged flow fields generated by direct \"physical\"\ninteractions. The latter can be short-ranged but lead to much longer-ranged\nfluid-mediated hydrodynamic forces, effectively amplifying the range over which\nparticles interact. These different fluid flows conspire to profoundly affect\nswarm morphology, kinetically stabilizing or destabilizing swarm configurations\nthat would arise in the absence of fluid. Depending upon the overall\ninteraction potential, the mechanism of swimming (e.g., pushers or pullers),\nand the degree of fluid opaqueness, we discover a number of new collective\nthree-dimensional patterns including flocks with prolate or oblate shapes,\nrecirculating peloton-like structures, and jet-like fluid flows that entrain\nparticles mediating their escape from the center of mill-like structures. Our\nresults reveal how the interplay among general physical elements influence\nfluid-mediated interactions and the self-organization, mobility, and stability\nof new three-dimensional swarms and suggest how they might be used to\nkinetically control their collective behavior."
    },
    {
        "anchor": "A stochastic model for bacteria-driven micro-swimmers: Experiments have recently shown the feasibility of utilising bacteria as\nmicro-scale robotic devices, with special attention paid to the development of\nbacteria-driven micro-swimmers taking advantage of built-in actuation and\nsensing mechanisms of cells. Here we propose a stochastic fluid dynamic model\nto describe analytically and computationally the dynamics of microscopic\nparticles driven by the motion of surface-attached bacteria undergoing\nrun-and-tumble motion. We compute analytical expressions for the rotational\ndiffusion coefficient, the swimming speed and the effective diffusion\ncoefficient. At short times, the mean squared displacement (MSD) is\nproportional to the square of the swimming speed, which is independent of the\nparticle size (for fixed density of attached bacteria) and scales linearly with\nthe number of attached bacteria; in contrast, at long times the MSD scales\nquadratically with the size of the swimmer and is independent of the number of\nbacteria. We then extend our result to the situation where the surface-attached\nbacteria undergo chemotaxis within the linear response regime. We demonstrate\nthat bacteria-driven particles are capable of performing artificial chemotaxis,\nwith a chemotactic drift velocity linear in the chemical concentration gradient\nand independent of the size of the particle. Our results are validated against\nnumerical simulations in the Brownian dynamics limit and will be relevant to\nthe optimal design of micro-swimmers for biomedical applications.",
        "positive": "Equation of state for random sphere packing with arbitrary adhesion and\n  friction: We systematically generate a large set of random micro-particle packings over\na wide range of adhesion and friction by means of adhesive contact dynamics\nsimulation. The ensemble of generated packings covers a range of volume\nfraction $\\phi$ from $0.135 \\pm 0.007$ to $0.639 \\pm 0.004$, and of\ncoordination number $Z$ from $2.11 \\pm 0.03$ to $6.40 \\pm 0.06$. We determine\n$\\phi$ and $Z$ at four limits (random close packing, random loose packing,\nadhesive close packing, and adhesive loose packing), and find a universal\nequation of state $\\phi(Z)$ to describe packings with arbitrary adhesion and\nfriction. From a mechanical equilibrium analysis, we determine a critical\nfriction coefficient $\\mu_{\\rm f, c}$: when the friction coefficient $\\mu_{\\rm\nf}$ is below $\\mu_{\\rm f, c}$, particles' rearrangements are dominated by\nsliding, otherwise, they are dominated by rolling. Because of this reason, both\n$\\phi(\\mu_{\\rm f})$ and $Z(\\mu_{\\rm f})$ change sharply across $\\mu_{\\rm f,\nc}$. Finally, we generalize the Maxwell counting argument to micro-particle\npackings, and show that the loosest packing, i.e., adhesive loose packing,\nsatisfies the isostatic condition at $Z=2$."
    },
    {
        "anchor": "A new model for fluid velocity slip on a solid surface: A general adsorption model is developed to describe the interactions between\nnear-wall fluid molecules and solid surface. This model serves as a framework\nfor the theoretical modelling of the boundary slip phenomena. Based on this\nadsorption model, a new general model for the slip velocity of fluids on solid\nsurfaces is introduced. The slip boundary condition at a fluid-solid interface\nhas hitherto been considered separately for gases and liquids. In this paper,\nwe show that the slip velocity in both gases and liquids may originate from\ndynamical adsorption processes at the interface. A unified analytical model\nthat is valid for both gas-solid and liquid-solid slip boundary conditions is\nproposed based on surface science theory. The corroboration with experimental\ndata extracted from the literature shows that the proposed model provides an\nimproved prediction compared to existing analytical models for gases at higher\nshear rates and close agreement for liquid-solid interfaces in general.",
        "positive": "Can adding oil control domain formation in binary amphiphile bilayers?: Bilayers formed of two species of amphiphile of different chain lengths may\nsegregate into thinner and thicker domains composed predominantly of the\nrespective species. Using a coarse-grained mean-field model, we investigate how\nmixing oil with the amphiphiles affects the structure and thickness of the\nbilayer at and on either side of the boundary between two neighbouring domains.\nIn particular, we find that oil molecules whose chain length is close to that\nof the shorter amphiphiles segregate to the thicker domain. This smooths the\nsurface of the hydrophobic bilayer core on this side of the boundary, reducing\nits area and curvature and their associated free-energy penalties. The\nsmoothing effect is weaker for oil molecules that are shorter or longer than\nthis optimum value: short molecules spread evenly through the bilayer, while\nlong molecules swell the thicker domain, increasing the surface area and\ncurvature of the bilayer core in the interfacial region. Our results show that\nadding an appropriate oil could make the formation of domain boundaries more or\nless favourable, raising the possibility of controlling the domain size\ndistribution."
    },
    {
        "anchor": "Statistical theory of individual activity coefficients of electrolytes\n  including multiple ionic charges: In previous work we developed a new statistical method for calculating the\nindividual activities of ions including the association of ions. Here we study\nmulti-particle electrostatic interactions connected within higher cluster\nintegrals and identify the ionization constants of the mass action law of\nassociating ion clusters. In contrast to Bjerrum and Fuoss, our concept of\nassociation is not based on spatial criteria, but instead on the strength of\ninteraction measured in powers of the Bjerrum parameter ($e^2 / D_0\nk_{\\text{B}} T a$ ; $a$ is contact) and defined by asymptotic properties of the\ncluster integrals. For ion pair formation our mass action constant is the\nclassical counterpart of Planck's famous hydrogenic partition function. As a\nrule, the new association constants are smaller than traditional expressions,\ne.g., by Fuoss and Kraus, in the interesting regions of interaction parameters\nabout fifty percent. Several examples including CaCl$_2$, MgCl$_2$,\nNa$_2$SO$_4$, K$_2$SO$_4$, LaCl$_3$ and a model of seawater are studied. For\nseveral associating electrolytes and seawater, reasonable agreement with\nexperiments and Monte Carlo results is achieved.",
        "positive": "Synchronization in dynamical networks of locally coupled self-propelled\n  oscillators: Systems of mobile physical entities exchanging information with their\nneighborhood can be found in many different situations. The understanding of\ntheir emergent cooperative behaviour has become an important issue across\ndisciplines, requiring a general conceptual framework in order to harvest the\npotential of these systems. We study the synchronization of coupled oscillators\nin time-evolving networks defined by the positions of self-propelled agents\ninteracting in real space. In order to understand the impact of mobility in the\nsynchronization process on general grounds, we introduce a simple model of\nself-propelled hard disks performing persistent random walks in 2$d$ space and\ncarrying an internal Kuramoto phase oscillator. For non-interacting particles,\nself-propulsion accelerates synchronization. The competition between agent\nmobility and excluded volume interactions gives rise to a richer scenario,\nleading to an optimal self-propulsion speed. We identify two extreme dynamic\nregimes where synchronization can be understood from theoretical\nconsiderations. A systematic analysis of our model quantifies the departure\nfrom the latter ideal situations and characterizes the different mechanisms\nleading the evolution of the system. We show that the synchronization of\nlocally coupled mobile oscillators generically proceeds through coarsening\nverifying dynamic scaling and sharing strong similarities with the phase\nordering dynamics of the 2$d$ XY model following a quench. Our results shed\nlight into the generic mechanisms leading the synchronization of mobile agents,\nproviding a efficient way to understand more complex or specific situations\ninvolving time-dependent networks where synchronization, mobility and excluded\nvolume are at play."
    },
    {
        "anchor": "Friction of rubber with surfaces patterned with rigid spherical\n  asperities: This paper reports on the frictional properties of smooth rubber substrates\nsliding against rigid surfaces covered with various densities of colloidal\nnano-particles (average diameter 77 nm). Friction experiments were carried out\nusing a transparent Poly(dimethyl siloxane) (PDMS) rubber contacting a silica\nlens with silica nano-particles sintered onto its surface. Using a previously\ndescribed methodology (Nguyen \\textit{et al.}, \\textit{J. of Adhesion}\n\\textbf{87} (2011) 235-250 ), surface shear stress and contact-pressure\ndistribution within the contact were determined from a measurement of the\ndisplacement field at the surface of the PDMS elastomer. Addition of silica\nnano-particles results in a strong, pressure-independent enhancement of the\nfrictional shear stress as compared to the smooth lens. The contribution of\nviscoelastic losses to these increased frictional properties is analyzed in the\nlight of a numerical model that solves the contact problem between the rubber\nand the rough surface. An order-of-magnitude agreement is obtained between\nexperimental and theoretical results, the latter showing that the calculation\nof viscoelastic dissipation within the contact is very sensitive to the details\nof the topography of the rigid asperities.",
        "positive": "Finite-size scaling investigation of the liquid-liquid critical point in\n  ST2 water and its stability with respect to crystallization: The liquid-liquid critical point scenario of water hypothesizes the existence\nof two metastable liquid phases---low-density liquid (LDL) and high-density\nliquid (HDL)---deep within the supercooled region. The hypothesis originates\nfrom computer simulations of the ST2 water model, but the stability of the LDL\nphase with respect to the crystal is still being debated. We simulate\nsupercooled ST2 water at constant pressure, constant temperature and constant\nnumber of molecules N for N<=729 and times up to 1000 ns. We observe clear\ndifferences between the two liquids, both structural and dynamical. Using\nseveral methods, including finite-size scaling, we confirm the presence of a\nliquid-liquid phase transition ending in a critical point. We find that the LDL\nis stable with respect to the crystal in 98% of our runs (we perform 372 runs\nfor LDL or LDL-like states), and in 100% of our runs for the two largest system\nsizes (N=512 and 729, for which we perform 136 runs for LDL or LDL-like\nstates). In all these runs tiny crystallites grow and then melt within 1000 ns.\nOnly for N<=343 we observe six events (over 236 runs for LDL or LDL-like\nstates) of spontaneous crystallization after crystallites reach an estimated\ncritical size of about 70+/-10 molecules."
    },
    {
        "anchor": "Polyelectrolyte chains in poor solvent. A variational description of\n  necklace formation: We study the properties of polyelectrolyte chains under different solvent\nconditions, using a variational technique. The free energy and the\nconformational properties of a polyelectrolyte chain are studied minimizing the\nfree energy $F_N$, depending on $N(N-1)/2$ trial probabilities that\ncharacterize the conformation of the chain. The Gaussian approximation is\nconsidered for a ring of length $2^4<N<2^{16}$ and for an open chain of length\n$2^4<N<2^9$ in poor and theta solvent conditions, including a Coulomb repulsion\nbetween the monomers. In theta solvent conditions the blob size is measured and\nfound in agreement with scaling theory, including charge depletion effects,\nexpected for the case of an open chain. In poor solvent conditions, a globule\ninstability, driven by electrostatic repulsion, is observed. We notice also\ninhomogeneous behavior of the monomer--monomer correlation function,\nreminiscence of necklace formation in poor solvent polyelectrolyte solutions. A\nglobal phase diagram in terms of solvent quality and inverse Bjerrum length is\npresented.",
        "positive": "Non-equilibrium steady states, coexistence and criticality in driven\n  quasi-two-dimensional granular matter: Nonequilibrium steady states of vibrated inelastic frictionless spheres are\ninvestigated in quasi-two-dimensional confinement via molecular dynamics\nsimulations. The phase diagram in the density-amplitude plane exhibits a\nfluidlike disordered and an ordered phase with threefold symmetry, as well as\nphase coexistence between the two. A dynamical mechanism exists that brings\nabout metastable traveling clusters and at the same time stable clusters with\nanisotropic shapes at low vibration amplitude. Moreover, there is a square\nbilayer state which is connected to the fluid by BKTHNY-type two-step melting\nwith an intermediate tetratic phase. The critical behavior of the two\ncontinuous transitions is studied in detail. For the fluid-tetratic transition,\ncritical exponents of $\\tilde{\\gamma}=1.73$, $\\eta_4 \\approx 1/4$, and $z=2.05$\nare obtained."
    },
    {
        "anchor": "Field-Theoretic Simulations of Polyelectrolyte Complexation: We briefly discuss our recent field-theoretic study of polyelectrolyte\ncomplexation, which occurs in solutions of two oppositely charged\npolyelectrolytes. Charged systems require theoretical methods beyond the\nmean-field (or self-consistent field) approximation; indeed, mean-field theory\nis qualitatively incorrect for such polyelectrolyte solutions. Both analytical\n(one-loop) and numerical (complex Langevin) methods to account for charge\ncorrelations are discussed. In particular, the first application of\nfield-theoretic simulations to polyelectrolyte systems is reported. The\npolyelectrolyte charge-charge correlation length and a phase diagram are\nprovided; effects of charge redistribution are qualitatively explored.",
        "positive": "Torsion instability of soft solid cylinders: The application of pure torsion to a long and thin cylindrical rod is known\nto provoke a twisting instability, evolving from an initial kink to a knot. In\nthe torsional parallel-plate rheometry of stubby cylinders, the geometrical\nconstraints impose zero displacement of the axis of the cylinder, preventing\nthe occurrence of such twisting instability. Under these experimental\nconditions, wrinkles occur on the cylinder's surface at a given critical angle\nof torsion. Here we investigate this subclass of elastic instability--which we\ncall torsion instability--of soft cylinders subject to a combined finite axial\nstretch and torsion, by applying the theory of incremental elastic deformation\nsuperimposed on finite strains. We formulate the incremental boundary elastic\nproblem in the Stroh differential form, and use the surface impedance method to\nbuild a robust numerical procedure for deriving the marginal stability curves.\nWe present the results for a Mooney-Rivlin material and study the influence of\nthe material parameters on the elastic bifurcation."
    },
    {
        "anchor": "First-order phase transition of the tethered membrane model on spherical\n  surfaces: We found that three types of tethered surface model undergo a first-order\nphase transition between the smooth and the crumpled phase. The first and the\nthird are discrete models of Helfrich, Polyakov, and Kleinert, and the second\nis that of Nambu and Goto. These are curvature models for biological membranes\nincluding artificial vesicles. The results obtained in this paper indicate that\nthe first-order phase transition is universal in the sense that the order of\nthe transition is independent of discretization of the Hamiltonian for the\ntethered surface model.",
        "positive": "Measuring Electric Fields From Surface Contaminants with Neutral Atoms: In this paper we demonstrate a technique of utilizing magnetically trapped\nneutral Rb-87 atoms to measure the magnitude and direction of stray electric\nfields emanating from surface contaminants. We apply an alternating external\nelectric field that adds to (or subtracts from) the stray field in such a way\nas to resonantly drive the trapped atoms into a mechanical dipole oscillation.\nThe growth rate of the oscillation's amplitude provides information about the\nmagnitude and sign of the stray field gradient. Using this measurement\ntechnique, we are able to reconstruct the vector electric field produced by\nsurface contaminants. In addition, we can accurately measure the electric\nfields generated from adsorbed atoms purposely placed onto the surface and\naccount for their systematic effects, which can plague a precision\nsurface-force measurement. We show that baking the substrate can reduce the\nelectric fields emanating from adsorbate, and that the mechanism for reduction\nis likely surface diffusion, not desorption."
    },
    {
        "anchor": "Protein Ground State Candidates in a Simple Model: An Exact Enumeration: The concept of the reduced set of contact maps is introduced. Using this\nconcept we find the ground state candidates for Hydrophobic-Polar lattice model\non a two dimensional square lattice. Using these results we exactly enumerate\nthe native states of all proteins for a wide range of energy parameters. In\nthis way, we show that there are some sequences, which have an absolute native\nstate. Moreover, we study the scale-dependence of the number of the members of\nthe reduced set, the number of ground state candidates, and the number of\nperfectly stable sequences by comparing the results for sequences with lengths\nof 6 up to 20.",
        "positive": "Energy Landscapes for Digital Alchemy: We apply energy landscape methods to digital alchemy, defining a system in\nwhich the parameters of the potential are treated as degrees of freedom. Using\ngeometrical optimisation, we locate minima and transition states on the\nlandscape for small clusters. We show that it is easy to find the parameters\nthat give the lowest energy minimum, and that the distribution of minima on the\nalchemical landscape is concentrated in particular areas. We also conclude that\nthe alchemical landscape is more frustrated, in terms of competition between\nlow energy structures separated by high barriers. Transition states on the\nalchemical landscape are classified by whether they become minima or transition\nstates when the potential parameters are fixed. Those that become minima have a\nsignificant alchemical component, while those that remain as transition states\ncan be characterised mainly in terms of atomic displacements."
    },
    {
        "anchor": "Composition and Resolution Dependence of Effective Coarse-Graining\n  Potentials in Multi-Resolution Simulations: Given that the physical properties of polymeric liquids extend on a wide\nrange of lengthscales, it is computationally convenient to represent them by\ncoarse-grained (CG) descriptions at various granularities to investigate local\nand global properties simultaneously. This paper addresses how modeling the\nsame system with mixed resolutions affects the consistency of the structural\nand thermodynamic properties, and shows that it is possible to formally derive\ninteracting potentials that ensure consistency of the relevant physical\nproperties in the mixed resolution region with the corresponding atomistic\nresolution simulations. The composition, temperature, and density dependences\nof such Mixed Resolution Potentials (MRPs) are investigated. In the limit of\nlong polymer chains, where Markovian statistics is obeyed, the MRPs are\nanalytically solved and decay with characteristic scaling exponents that depend\non the mixture composition and CG resolution of the two components. Adopting\nMRPs simplifies the structure of multi-resolution simulations while\nquantitatively producing the structural and thermodynamical properties of the\nrelated atomistic systems such as radial distribution function and pressure.",
        "positive": "Discrete aqueous solvent effects and possible attractive forces: We study discrete solvent effects on the interaction of two parallel charged\nsurfaces in ionic aqueous solution. These effects are taken into account by\nadding a bilinear non-local term to the free energy of Poisson-Boltzmann\ntheory. We study numerically the density profile of ions between the two\nplates, and the resulting inter-plate pressure. At large plate separations the\ntwo plates are decoupled and the ion distribution can be characterized by an\neffective Poisson-Boltzmann charge that is smaller than the nominal charge. The\npressure is thus reduced relative to Poisson-Boltzmann predictions. At plate\nseparations below ~2 nm the pressure is modified considerably, due to the\nsolvent mediated short-range attraction between ions in the the system. For\nhigh surface charges this contribution can overcome the mean-field repulsion\ngiving rise to a net attraction between the plates."
    },
    {
        "anchor": "Effect of interparticle interaction on motility induced phase separation\n  of self-propelled inertial disks: Phase diagram of the phenomenon of motility induced phase separation (MIPS)\nfor a collection of self-propelled interacting disks is explored using Langevin\ndynamics simulation with particular emphasis on disk wall softness and the\nrange of interaction amongst disks. We bring out important changes in the MIPS\nphase diagram both due to softness and inertia of the disks. Specifically, we\nshow that overdamped softer disks phase separate while MIPS becomes possible\nonly for harder disks in the inertial limit. Unlike most of the earlier studies\non MIPS which consider hard-core disks, our findings may be directly applicable\nto soft active matter for a range of biological systems.",
        "positive": "Broadband dielectric behavior of MIL-100 metal-organic framework as a\n  function of structural amorphization: The performance of modern electronics is associated with the multi-layered\ninterconnects, encouraging the development of a low-k dielectrics. Herein, we\nstudied the effects of phase transition from crystalline to amorphous on\ndielectric, optical and electrical properties of MIL-100 (Fe) and Basolite F300\nmetal-organic framework (MOF) obtained using different synthesis techniques in\nboth the radio (4-1.5 MHz) and infrared (1.2-150 THz) frequency regimes, which\nare important for the microelectronics, infrared optical sensors, and\nhigh-frequency telecommunications. The impact of amorphization on broadband\ndielectric response was established based on: (1) The comparison in the\ndielectric characteristics of a commercially available amorphous Basolite F300\nversus a mechanochemically synthesized crystalline MIL-100 in the MHz region.\n(2) By tracking the frequency shifts in the vibrational modes of MIL-100\nstructure in the far-IR (phonons) and mid-IR regions. We showed that various\nparameters such as pelleting pressure, temperature, frequency, density, and\ndegree of amorphization greatly affect the dielectric properties of the\nframework. We also investigated the influence of temperature (20-100 {\\deg}C)\non the electric and dielectric response in the MHz region, crucial for all\nelectronic devices."
    },
    {
        "anchor": "Stability and Decay Rates of Non-Isotropic Attractive Bose-Einstein\n  Condensates: Non-Isotropic Attractive Bose-Einstein condensates are investigated with\nNewton and inverse Arnoldi methods. The stationary solutions of the\nGross-Pitaevskii equation and their linear stability are computed. Bifurcation\ndiagrams are calculated and used to find the condensate decay rates\ncorresponding to macroscopic quantum tunneling, two-three body inelastic\ncollisions and thermally induced collapse.\n  Isotropic and non-isotropic condensates are compared. The effect of\nanisotropy on the bifurcation diagram and the decay rates is discussed.\nSpontaneous isotropization of the condensates is found to occur. The influence\nof isotropization on the decay rates is characterized near the critical point.",
        "positive": "A finite element method of the self-consistent field theory on general\n  curved surfaces: Block copolymers provide a wonderful platform in studying the soft condensed\nmatter systems. Many fascinating ordered structures have been discovered in\nbulk and confined systems. Among various theories, the self-consistent field\ntheory (SCFT) has been proven to be a powerful tool for studying the\nequilibrium ordered structures. Many numerical methods have been developed to\nsolve the SCFT model. However, most of these focus on the bulk systems, and\nlittle work on the confined systems, especially on general curved surfaces. In\nthis work, we developed a linear surface finite element method, which has a\nrigorous mathematical theory to guarantee numerical precsion, to study the\nself-assembled phases of block copolymers on general curved surfaces based on\nthe SCFT. Furthermore, to capture the consistent surface for a given\nself-assembled pattern, an adaptive approach to optimize the size of the\ngeneral curved surface has been proposed. To demonstrate the power of this\napproach, we investigate the self-assembled patterns of diblock copolymers on\nseveral distinct curved surfaces, including five closed surfaces and an\nunclosed surface. Numerical results illustrate the efficiency of the proposed\nmethod. The obtained ordered structures are consistent with the previous\nresults on standard surfaces, such as sphere and torus. Certainly, the proposed\nnumerical framework has the capability of studying the phase behaviors on\ngeneral surfaces precisely."
    },
    {
        "anchor": "Anomalous fluctuations of active polar filaments: Using a simple model, we study the fluctuating dynamics of inextensible,\nsemiflexible polar filaments interacting with active and directed force\ngenerating centres such as molecular motors. Taking into account the fact that\nthe activity occurs on time-scales comparable to the filament relaxation time,\nwe obtain some unexpected differences between both the steady-state and\ndynamical behaviour of active as compared to passive filaments. For the\nstatics, the filaments have a {novel} length-scale dependent rigidity.\nDynamically, we find strongly enhanced anomalous diffusion.",
        "positive": "Structural and dynamical features of multiple metastable glassy states\n  in a colloidal system with competing interactions: Systems in which a short-ranged attraction and long-ranged repulsion compete\nare intrinsically frustrated, leading their structure and dynamics to be\ndominated either by mesoscopic order or by metastable disorder. Here we report\nthe latter case in a colloidal system with long-ranged electrostatic repulsions\nand short-ranged depletion attractions. We find a variety of states exhibiting\nslow non-diffusive dynamics: a gel, a glassy state of clusters, and a state\nreminiscent of a Wigner glass. Varying the interactions, we find a continuous\ncrossover between the Wigner and cluster glassy states, and a sharp\ndiscontinuous transition between the Wigner glassy state and gel. This\ndifference reflects the fact that dynamic arrest is driven by repulsion for the\ntwo glassy states and attraction in the case of the gel."
    },
    {
        "anchor": "Rheology of cholesteric blue phases: Blue phases of cholesteric liquid crystals offer a spectacular example of\nnaturally occurring disclination line networks. Here we numerically solve the\nhydrodynamic equations of motion to investigate the response of three types of\nblue phases to an imposed Poiseuille flow. We show that shear forces bend and\ntwist and can unzip the disclination lines. Under gentle forcing the network\nopposes the flow and the apparent viscosity is significantly higher than that\nof an isotropic liquid. With increased forcing we find strong shear thinning\ncorresponding to the disruption of the defect network. As the viscosity starts\nto drop, the imposed flow sets the network into motion. Disclinations break-up\nand re-form with their neighbours in the flow direction. This gives rise to\noscillations in the time-dependent measurement of the average stress.",
        "positive": "Determination of thermal and optical parameters of melanins by\n  photopyroelectric spectroscopy: Photopyroelectric spectroscopy (PPE) was used to study the thermal and\noptical properties of electropolymerized melanins. The photopyroelectric\nintensity signal and its phase were independently measured as a function of\nwavelength, as well as a function of chopping frequency for a given wavelength\nin the saturation part of the PPE spectrum. Equations for both the intensity\nand the phase of the PPE signal were used to fit the experimental results. From\nthe fittings we obtained for the first time, with great accuracy, the thermal\ndiffusivity coefficient, the thermal conductivity and the specific heat of the\nsamples, as well as a value for the condensed phase optical gap, which we found\nto be 1.70 eV."
    },
    {
        "anchor": "Multi-chain Slip-spring Model for Entangled Polymer Dynamics: It has been established that the entangled polymer dynamics can be reasonably\ndescribed by single chain models such as tube and slip-link models. Although\nthe entanglement effect is a result of the hard-core interaction between\nchains, linkage between the single chain models and the real multi-chain system\nhas not been established yet. In this study, we propose a multi-chain\nslip-spring model where bead-spring chains are dispersed in space and connected\nby slip-springs inspired by the single chain slip-spring model [A. E. Likhtman,\nMacromolecules 38, 6128 (2005)]. In this model the entanglement effect is\nreplaced by the slip-springs, not by the hard-core interaction between beads so\nthat this model is located in the niche between conventional multi-chain\nsimulations and single chain models. The set of state variables are the\nposition of beads and the connectivity (indices) of the slip-springs between\nbeads. The dynamics of the system is described by the time evolution equation\nand stochastic transition dynamics for these variables. We propose a simple\nmodel which is based on the well-defined total free-energy and the detailed\nbalance condition. The free energy in our model contains a repulsive\ninteraction between beads, which compensate the attractive interaction\nartificially generated by the slip-springs. The explicit expression of linear\nrelaxation modulus is also derived by the linear response theory. We also\npropose a possible numerical scheme to perform simulations. Simulations\nreproduced expected bead number dependence in transitional regime between Rouse\nand entangled dynamics for the chain structure, the central bead diffusion, and\nthe linear relaxation modulus.",
        "positive": "Acoustic Monitoring of Inelastic Compaction in Porous Granular Materials: We study the transition from cohesive to noncohesive granular states of\nsynthetic rocks under oedometric loading, combining simultaneous measurements\nof ultrasound velocity and acoustic emissions. Our samples are agglomerates\nmade of glass beads bonded with a few percent of cement, either ductile or\nbrittle. These cemented granular samples exhibit an inelastic compaction beyond\ncertain axial stresses likely due to the formation of compaction bands, which\nis accompanied by a significant decrease of compressional wave velocity. Upon\nsubsequent cyclic unloading and reloading with constant consolidation stress,\nwe found the mechanical and acoustic responses similar to those in noncohesive\ngranular materials, which can be interpreted within the effective medium theory\nbased on the Digby bonding model. Moreover, this model allows P-wave velocity\nmeasured at vanishing pressure to be interpreted as an indicator of the\ndebonding on the scale of grain contact. During the inelastic compaction,\nstick-slip like stress drops were observed in brittle cement-bonded granular\nsamples accompanied by the instantaneous decrease of the P-wave velocity and\nacoustic emissions which display an Omori-like law for foreshocks, i.e.,\nprecursors. By contrast, mechanical responses of ductile cement-bonded granular\nsamples are smooth (without visible stick-slip like stress drops) and mostly\naseismic. By applying a cyclic loading and unloading with increasing\nconsolidation stress, we observed a Kaiser-like memory effect in the brittle\ncement-bonded sample in the weakly damaged state which tends to disappear when\nthe bonds are mostly broken in the non-cohesive granular state after\nlarge-amplitude loading. Our study shows that the macroscopic ductile and\nbrittle behavior of cemented granular media is controlled by the local\nprocesses on the scale of the bonds between grains."
    },
    {
        "anchor": "Polar nature of the ferro-electric nematic studied by dielectric\n  spectroscopy: The nematic-nematic transitions in a nematic compound DIO are studied in\nhomogeneously planar and homeotropic aligned cells using dielectric\nspectroscopy in the frequency range 0.1 Hz to 10 MHz over a wide range of\ntemperatures. Three relaxation processes are identified in this material. All\nthe three relaxation processes show large jumps in the dielectric strength and\ndiscontinuity in frequency at the NX to NF transition, indicative of it being a\nfirst order phase transition. Unlike a conventional nematic liquid crystalline\nmaterial that usually shows molecular relaxation processes at higher\nfrequencies, this material shows three processes at relatively lower\nfrequencies. The three processes are found to be collective in nature. The\nleast frequency process is proven to be due to the conductivity of ions in the\nmedium and due to the accumulation of charge at the alignment layers unlike\nmistakenly reported in the literature otherwise. The mode at the highest\nfrequency is proven to be due to the ferroelectric domains in the NF phase.\nThis is evidenced by its dielectric strength two orders of magnitude higher in\na homeotropic aligned cell than planar aligned cell. Its mechanism is soft mode\nlike in the N phase. The intermediate frequency mode is proven to be due to the\ncorrelation of molecules of the medium as is normally observed in liquid\ncrystalline cybotactic clusters.",
        "positive": "Comparing the buckling strength of spherical shells with dimpled versus\n  bumpy defects: We investigate the effect of defect geometry in dictating the sensitivity of\nthe critical buckling conditions of spherical shells under external pressure\nloading. Specifically, we perform a comparative study between shells containing\ndimpled (inward) versus bumpy (outward) Gaussian defects. The former has become\nthe standard shape in many recent shell-buckling studies, whereas the latter\nhas remained mostly unexplored. We employ finite-element simulations, which\nwere validated previously against experiments, to compute the knockdown factors\nfor the two cases while systematically exploring the parameter space of the\ndefect geometry. For the same magnitudes of the amplitude and angular width of\nthe defect, we find that shells containing bumpy defects consistently exhibit\nsignificantly higher knockdown factors than shells with the more classic\ndimpled defects. Furthermore, the relationship of the knockdown as a function\nof the amplitude and width of the defect is qualitatively different between the\ntwo cases, which also exhibit distinct post-buckling behavior. A speculative\ninterpretation of the results is provided based on the qualitative differences\nin the mean-curvature profiles of the two cases."
    },
    {
        "anchor": "Friction mediated phase transition in confined active nematics: Using a minimal continuum model, we investigate the interplay between\ncircular confinement and substrate friction in active nematics. Upon increasing\nthe friction from low to high, we observe a dynamical phase transition from a\ncirculating flow phase to an anisotropic flow phase in which the flow tends to\nalign perpendicular to the nematic director at the boundary. We demonstrate\nthat both the flow structure and dynamic correlations in the latter phase\ndiffer from those of an unconfined, active turbulent system and may be\ncontrolled by the prescribed nematic boundary conditions. Our results show that\nsubstrate friction and geometric confinement act as valuable control parameters\nin active nematics.",
        "positive": "Elastocapillarity: Surface Tension and the Mechanics of Soft Solids: It is widely appreciated that surface tension can dominate the behavior of\nliquids at small scales. Solids also have surface stresses of a similar\nmagnitude, but they are usually overlooked. However, recent work has shown that\nthese can play an central role in the mechanics of soft solids such as gels.\nHere, we review this emerging field. We outline the theory of surface stresses,\nfrom both mechanical and thermodynamic perspectives, emphasizing the\nrelationship between surface stress and surface energy. We describe a wide\nrange of phenomena at interfaces and contact lines where surface stresses play\nan important role. We highlight how surface stresses causes dramatic departures\nfrom classic theories for wetting (Young-Dupr\\'{e}), adhesion\n(Johnson-Kendall-Roberts), and composites (Eshelby). A common thread is the\nimportance of the ratio of surface stress to an elastic modulus, which defines\na length scale below which surface stresses can dominate."
    },
    {
        "anchor": "Pressure Driven Flow of Polymer Solutions in Nanoscale Slit Pores: Polymer solutions subject to pressure driven flow and in nanoscale slit pores\nare systematically investigated using the dissipative particle dynamics\napproach. We investigated the effect of molecular weight, polymer concentration\nand flow rate on the profiles across the channel of the fluid and polymer\nvelocities, polymers density, and the three components of the polymers radius\nof gyration. We found that the mean streaming fluid velocity decreases as the\npolymer molecular weight or/and polymer concentration is increased, and that\nthe deviation of the velocity profile from the parabolic profile is accentuated\nwith increase in polymer molecular weight or concentration. We also found that\nthe distribution of polymers conformation is highly anisotropic and non-uniform\nacross the channel. The polymer density profile is also found to be\nnon-uniform, exhibiting a local minimum in the center-plane followed by two\nsymmetric peaks. We found a migration of the polymer chains either from or\ntowards the walls. For relatively long chains, as compared to the thickness of\nthe slit, a migration towards the walls is observed. However, for relatively\nshort chains, a migration away from the walls is observed.",
        "positive": "The structure of clusters formed by Stockmayer supracolloidal magnetic\n  polymers: Unlike Stockmayer fluids, that prove to undergo gas-liquid transition on\ncooling, the system of dipolar hard or soft spheres without any additional\ncentral attraction so far has not been shown to have a critical point. Instead,\nin the latter, one observes diverse self-assembly scenarios. Crosslinking\ndipolar soft spheres into supracolloidal magnetic polymer-like structures\n(SMPs) changes the self-assembly behaviour. Moreover, aggregation in systems of\nSMPs strongly depends on the constituent topology. For Y- and X-shaped SMPs,\nunder the same conditions in which dipolar hard spheres would form chains, the\nformation of very large loose gel-like clusters was observed [Journal of\nMolecular Liquids, 271, 631 (2018)]. In this work, using molecular dynamics\nsimulations, we investigate self-assembly in suspensions of four topologically\ndifferent SMPs -- chains, rings, X and Y -- monomers in which interact via\nStockmayer potential. As expected, compact drop-like clusters are formed by\nSMPs in all cases if the central isotropic attraction is introduced, however,\ntheir shape and internal structure turn out to depend on the SMPs topology."
    },
    {
        "anchor": "Roles of icosahedral and crystal-like order in hard spheres glass\n  transition: A link between structural ordering and slow dynamics has recently attracted\nmuch attention from the context of the origin of glassy slow dynamics.\nCandidates for such structural order are icosahedral, exotic amorphous, and\ncrystal-like. Each type of order is linked to a different scenario of glass\ntransition. Here we experimentally access local structural order in\npolydisperse hard spheres by particle-level confocal microscopy. We identify\nthe key structures as icosahedral and FCC-like order, both statistically\nassociated with slow particles. However, when approaching the glass transition,\nthe icosahedral order does not grow in size whereas crystal-like order grows.\nIt is the latter that governs the dynamics and is linked to dynamic\nheterogeneity. This questions the direct role of the local icosahedral ordering\nin glassy slow dynamics and suggests that the growing lengthscale of structural\norder is essential for the slowing down of dynamics and the nonlocal\ncooperativity in particle motion.",
        "positive": "Odd Cosserat elasticity in active materials: Stress-strain constitutive relations in solids with an internal angular\ndegree of freedom can be modelled using Cosserat (also called micropolar)\nelasticity. In this paper, we explore the phenomenology for a natural extension\nof Cosserat materials that includes chiral active components and odd\nelasticity. We calculate static elastic properties of such a solid, where we\nshow that static response to rotational stresses leads to strains that depend\non both Cosserat and odd elasticity. We then compute the dispersion of linear\nsolutions in these odd Cosserat materials in the overdamped regime and find the\npresence of \\emph{exceptional points} in the dispersion relation. We discover\nthat these exceptional points create a sharp boundary between a\nCosserat-dominated regime of complete wave attenuation and an\nodd-elasticity-dominated regime of propagating waves. We conclude by showing\nthe effect of Cosserat and odd elastic terms on the polarization of Rayleigh\nsurface waves."
    },
    {
        "anchor": "Hyperuniformity and phase enrichment in vortex and rotor assemblies: Ensembles of particles rotating in a two-dimensional fluid can exhibit\nchaotic dynamics yet develop signatures of hidden order. Such \"rotors\" are\nfound in the natural world spanning vastly disparate length scales - from the\nrotor proteins in cellular membranes to models of atmospheric dynamics. Here we\nshow that an initially random distribution of either ideal vortices in an\ninviscid fluid, or driven rotors in a viscous membrane, spontaneously self\nassembles. Despite arising from drastically different physics, these systems\nshare a Hamiltonian structure that sets geometrical conservation laws resulting\nin distinct structural states. We find that the rotationally invariant\ninteractions isotropically suppress long wavelength fluctuations - a hallmark\nof a disordered hyperuniform material. With increasing area fraction, the\nsystem orders into a hexagonal lattice. In mixtures of two co-rotating\npopulations, the stronger population will gain order from the other and both\nwill become phase enriched. Finally, we show that classical 2D point vortex\nsystems arise as exact limits of the experimentally accessible microscopic\nmembrane rotors, yielding a new system through which to study topological\ndefects.",
        "positive": "Laning, Thinning and Thickening of Sheared Colloids in a Two-dimensional\n  Taylor-Couette Geometry: We investigate the dynamics and rheological properties of a circular\ncolloidal cluster that is continuously sheared by magnetic and optical torques\nin a two-dimensional (2D) Taylor-Couette geometry. By varying the two driving\nfields, we obtain the system flow diagram and report the velocity profiles\nalong the colloidal structure. We then use the inner magnetic trimer as a\nmicrorheometer, and observe continuous thinning of all particle layers followed\nby thickening of the third one above a threshold field. Experimental data are\nsupported by Brownian dynamics simulations. Our approach gives a unique\nmicroscopic view on how the structure of strongly confined colloidal matter\nweakens or strengthens upon shear, envisioning the engineering of rheological\ndevices at the microscales."
    },
    {
        "anchor": "Nonequilibrium steady states in a vibrated-rod monolayer: tetratic,\n  nematic and smectic correlations: We study experimentally the nonequilibrium phase behaviour of a horizontal\nmonolayer of macroscopic rods. The motion of the rods in two dimensions is\ndriven by vibrations in the vertical direction. Aside from the control\nvariables of packing fraction and aspect ratio that are typically explored in\nmolecular liquid crystalline systems, due to the macroscopic size of the\nparticles we are also able to investigate the effect of the precise shape of\nthe particle on the steady states of this driven system. We find that the shape\nplays an important role in determining the nature of the orientational ordering\nat high packing fraction. Cylindrical particles show substantial tetratic\ncorrelations over a range of aspect ratios where spherocylinders have\npreviously been shown by Bates et al (JCP 112, 10034 (2000)) to undergo\ntransitions between isotropic and nematic phases. Particles that are thinner at\nthe ends (rolling pins or bails) show nematic ordering over the same range of\naspect ratios, with a well-established nematic phase at large aspect ratio and\na defect-ridden nematic state with large-scale swirling motion at small aspect\nratios. Finally, long-grain, basmati rice, whose geometry is intermediate\nbetween the two shapes above, shows phases with strong indications of smectic\norder.",
        "positive": "Self-organisation of semi-flexible rod-like particles: We report on a comprehensive computer simulation study of the liquid-crystal\nphase behaviour of purely repulsive, semi-flexible rod-like particles. For the\nfour aspect ratios we consider, the particles form five distinct phases\ndepending on their packing fraction and bending flexibility: the isotropic,\nnematic, smectic A, smectic B and crystal phase. Upon increasing the particle\nbending flexibility, the various phase transitions shift to larger packing\nfractions. Increasing the aspect ratio achieves the opposite effect. We find\ntwo different ways how the layer spacing of the particles in the smectic A\nphase may respond to an increase in concentration. The layer spacing may either\ndecrease or increase depending on the aspect ratio and flexibility. For the\nsmectic B and the crystalline phases, increasing the concentration always\ndecreases the layer spacing. We find that the layer spacing jumps to a larger\nvalue on transitioning from the smectic A to the smectic B phase."
    },
    {
        "anchor": "The reversibility and first-order nature of liquid-liquid transition in\n  a molecular liquid: Liquid-liquid transition is an intriguing phenomenon in which a liquid\ntransforms into another liquid via the first-order transition. For molecular\nliquids, however, it always takes place in a supercooled liquid state\nmetastable against crystallization, which has led to a number of serious\ndebates concerning its origin: liquid-liquid transition vs. unusual\nnano-crystal formation. Thus, there have so far been no single example free\nfrom such debates. Here we show the first firm experimental evidence that the\ntransition is truly liquid-liquid transition and not nano-crystallization for a\nmolecular liquid, triphenyl phosphite. We kinetically isolate the reverse\nliquid-liquid transition from glass transition and crystallization with an\nextremely high heating rate of flash differential scanning calorimetry, and\nprove the reversibility and first-order nature of liquid-liquid transition. Our\nfinding not only deepens our physical understanding of liquid-liquid transition\nbut also will initiate a new phase of its research from both fundamental and\napplications viewpoints.",
        "positive": "Effects of inertia on the steady-shear rheology of disordered solids: We study the finite-shear-rate rheology of disordered solids by means of\nmolecular dynamics simulations in two dimensions. By systematically varying the\ndamping magnitude $\\zeta$ in the low-temperature limit, we identify two well\ndefined flow regimes, separated by a thin (temperature-dependent) crossover\nregion. In the overdamped regime, the athermal rheology is governed by the\ncompetition between elastic forces and viscous forces, whose ratio gives the\nWeissenberg number $Wi= \\zeta \\dot\\gamma$ (up to elastic parameters); the\nmacroscopic stress $\\Sigma$ follows the frequently encountered Herschel-Bulkley\nlaw $\\Sigma= \\Sigma\\_0 + k \\sqrt{Wi}$, with yield stress\n$\\Sigma\\_0\\textgreater{}0$. In the underdamped (inertial) regime, dramatic\nchanges in the rheology are observed for low damping: the flow curve becomes\nnon-monotonic. This change is not caused by longer-lived correlations in the\nparticle dynamics at lower damping; instead, for weak dissipation, the sample\nheats up considerably due to, and in proportion to, the driving. By suitably\nthermostatting more or less underdamped systems, we show that their rheology\nonly depends on their kinetic temperature and the shear rate, rescaled with\nEinstein's vibration frequency."
    },
    {
        "anchor": "Spinodal of supercooled polarizable water: We develop a series of molecular dynamics computer simulations of liquid\nwater, performed with a polarizable potential model, to calculate the spinodal\nline and the curve of maximum density inside the metastable supercooled region.\nAfter analysing the structural properties,the liquid spinodal line is followed\ndown to T=210 K. A monotonic decrease is found in the explored region. The\ncurve of maximum density bends on approaching the spinodal line. These results,\nin agreement with similar studies on non polarizable models of water, are\nconsistent with the existence of a second critical point for water.",
        "positive": "From Capillary Condensation to Interface Localization Transitions in\n  Colloid Polymer Mixtures Confined in Thin Film Geometry: Monte Carlo simulations of the Asakura-Oosawa (AO) model for colloid-polymer\nmixtures confined between two parallel repulsive structureless walls are\npresented and analyzed in the light of current theories on capillary\ncondensation and interface localization transitions. Choosing a polymer to\ncolloid size ratio of q=0.8 and studying ultrathin films in the range of D=3 to\nD=10 colloid diameters thickness, grand canonical Monte Carlo methods are used;\nphase transitions are analyzed via finite size scaling, as in previous work on\nbulk systems and under confinement between identical types of walls. Unlike the\nlatter work, inequivalent walls are used here: while the left wall has a\nhard-core repulsion for both polymers and colloids, at the right wall an\nadditional square-well repulsion of variable strength acting only on the\ncolloids is present. We study how the phase separation into colloid-rich and\ncolloid-poor phases occurring already in the bulk is modified by such a\nconfinement. When the asymmetry of the wall-colloid interaction increases, the\ncharacter of the transition smoothly changes from capillary condensation-type\nto interface localization-type. The critical behavior of these transitions is\ndiscussed, as well as the colloid and polymer density profiles across the film\nin the various phases, and the correlation of interfacial fluctuations in the\ndirection parallel to the confining walls. The experimental observability of\nthese phenomena also is briefly discussed."
    },
    {
        "anchor": "Sensitivity of arrest in mode-coupling glasses to low-q structure: We quantify, within mode coupling theory, how changes in the liquid structure\naffect that of the glass. Apart from the known sensitivity to the structure\nfactor $S(q)$ at wavevectors around the first sharp diffraction peak $q_0$, we\nfind a strong (and inverted) response to structure at wavevectors \\emph{below}\nthis peak: an increase in $S(q_0/2)$ {\\em lowers} the degree of arrest over a\nwide $q$-range. This strong sensitivity to `caged cage' packing effects, on\nlength scales of order 2d, is much weaker in attractive glasses where\nshort-range bonding dominates the steric caging effect.",
        "positive": "Mechanical Properties of End-crosslinked Entangled Polymer Networks\n  using Sliplink Brownian Dynamics Simulations: The mechanical properties of a polymeric network containing both crosslinks\nand sliplinks (entanglements) are studied using a multi-chain Brownian dynamics\nsimulation. We coarse-grain at the level of chain segments connecting\nconsecutive nodes (cross- or sliplinks), with particular attention to the\nGaussian statistics of the network. Affine displacement of nodes is not\nimposed: their displacement as well as sliding of monomers through sliplinks is\ngoverned by force balances. The simulation results of stress in uniaxial\nextension and the full stress tensor in simple shear including the (non-zero)\nsecond normal stress difference are presented for monodisperse chains with up\nto 18 entanglements between two crosslinks. The cases of two different force\nlaws of the subchains (Gaussian chains and chains with finite extensibility)\nfor two different numbers of monomers in a subchain (no = 50 and no = 100) are\nexamined. It is shown that the additivity assumption of slip- and crosslink\ncontribution holds for sufficiently long chains with two or more entanglements,\nand that it can be used to construct the strain response of a network of\ninfinitely long chains. An important consequence is that the contribution of\nsliplinks to the small-strain shear modulus is about &#8532; of the\ncontribution of a crosslink."
    },
    {
        "anchor": "Lateral diffusion induced by active proteins in a biomembrane: We discuss the hydrodynamic collective effects due to active protein\nmolecules that are immersed in lipid bilayer membranes and modeled as\nstochastic force dipoles. We specifically take into account the presence of the\nbulk solvent which surrounds the two-dimensional fluid membrane. Two membrane\ngeometries are considered: the free membrane case and the confined membrane\ncase. Using the generalized membrane mobility tensors, we estimate the active\ndiffusion coefficient and the drift velocity as a function of the size of a\ndiffusing object. The hydrodynamic screening lengths distinguish the two\nasymptotic regimes of these quantities. Furthermore, the competition between\nthe thermal and non-thermal contributions in the total diffusion coefficient is\ncharacterized by two length scales corresponding to the two membrane\ngeometries. These characteristic lengths describe the crossover between\ndifferent asymptotic behaviors when they are larger than the hydrodynamic\nscreening lengths.",
        "positive": "Fresh Cement as a Frictional Non-Brownian Suspension: Cement is an essential construction material due to its ability to flow\nbefore later setting, however the rheological properties must be tightly\ncontrolled. Despite this, much understanding remains empirical. Using a\ncombination of continuous and oscillatory shear flow, we compare fresh Portland\ncement suspensions to previous measurements on model non-Brownian suspensions\nto gain a micro-physical understanding. Comparing steady and small-amplitude\noscillatory shear, we reveal two distinct jamming concentrations, $\\phi_{\\mu}$\nand $\\phi_{\\rm rcp}$, where the respective yield stresses diverge. As in model\nsuspensions, the steady-shear jamming point is notably below the oscillatory\njamming point, $\\phi_{\\mu} < \\phi_{\\rm rcp}$, suggesting that it is tied to\nfrictional particle contacts. These results indicate that recently established\nmodels for the rheology of frictional, adhesive non-Brownian suspensions can be\napplied to fresh cement pastes, offering a new framework to understand the role\nof additives and fillers. Such micro-physical understanding can guide\nformulation changes to improve performance and reduce environmental impact."
    },
    {
        "anchor": "Linear stability of an active fluid interface: Motivated by studies suggesting that the patterns exhibited by the\ncollectively expanding fronts of thin cells during the closing of a wound [Mark\net al., Biophys. J., 98:361-370, 2010] and the shapes of single cells crawling\non surfaces [Callan-Jones et al., Phys. Rev. Lett., 100:258106, 2008] are due\nto fingering instabilities, we investigate the stability of actively driven\ninterfaces under Hele-Shaw confinement. An initially radial interface between a\npair of viscous fluids is driven by active agents. Surface tension and bending\nrigidity resist deformation of the interface. A point source at the origin and\na distributed source are also included to model the effects of injection or\nsuction, and growth or depletion, respectively. Linear stability analysis\nreveals that for any given initial radius of the interface, there are two key\ndimensionless driving rates that determine interfacial stability. We discuss\nstability regimes in a state space of these parameters and their implications\nfor biological systems. An interesting finding is that an actively mobile\ninterface is susceptible to fingering instability irrespective of viscosity\ncontrast.",
        "positive": "Analysis of Profile and Morphology of Colloidal Deposits obtained from\n  Evaporating Sessile Droplets: We experimentally investigate the profile and morphology of the ring-like\ndeposits obtained after evaporation of a sessile water droplet containing\npolystyrene colloidal particles on a hydrophilic glass substrate. In\nparticular, the coupled effect of particle size and concentration are studied.\nThe deposits were qualitatively visualized under an optical microscope and\nprofile of the ring was measured by an optical profilometer. The profile of the\nring resembles a partial torus-like shape for all cases of particles size and\nconcentration. The cracks on the surface of the ring were found to occur only\nat smaller particle size and larger concentration. We plot a regime map to\nclassify three deposit types - discontinuous monolayer ring, continuous\nmonolayer ring, and multiple layers ring - on particles concentration -\nparticle size plane. Our data shows a possible existence of a critical\nconcentration (particle size) for a given particle size (concentration) at\nwhich the monolayer ring forms. For the larger particle sizes, the immersion\ncapillary forces between the particles dominate, aiding the formation of a\nmonolayer ring of the particles. The relative mass of the particles accumulated\nin the ring is lesser in cases of the monolayer ring. We measure the width and\nheight of the ring and show that they scale with particle concentration by a\npower law for the multiple layers ring. This scaling corroborates with an\nexisting continuum based theoretical model. We briefly discuss the effect of\nthe interaction of growing deposit with shrinking free surface on the ring\ndimensions and profile. The present results aid understanding of the ring\nformation process and will be useful in guiding the design of self-assemblies\nof the colloidal particles formed by the evaporating droplets."
    },
    {
        "anchor": "Soft effective interactions between weakly charged polyelectrolyte\n  chains: We apply extensive Molecular Dynamics simulations and analytical\nconsiderations in order to study the conformations and the effective\ninteractions between weakly charged, flexible polyelectrolyte chains in\nsalt-free conditions. We focus on charging fractions lying below 20%, for which\ncase there is no Manning condensation of counterions and the latter can be thus\npartitioned in two states: those that are trapped within the region of the\nflexible chain and the ones that are free in the solution. We examine the\npartition of counterions in these two states, the chain sizes and the monomer\ndistributions for various chain lengths, finding that the monomer density\nfollows a Gaussian shape. We calculate the effective interaction between the\ncenters of mass of two interacting chains, under the assumption that the chains\ncan be modeled as two overlapping Gaussian charge profiles. The analytical\ncalculations are compared with measurements from Molecular Dynamics\nsimulations. Good quantitative agreement is found for charging fractions below\n10%, where the chains assume coil-like configurations, whereas deviations\ndevelop for charge fraction of 20%, in which case a conformational transition\nof the chain towards a rodlike configuration starts to take place.",
        "positive": "Observation of Long-lived Vortex Aggregates in Rapidly Rotating\n  Bose-Einstein Condensates: We study the formation of large vortex aggregates in a rapidly rotating\ndilute-gas Bose-Einstein condensate. When we remove atoms from the rotating\ncondensate with a tightly focused, resonant laser, the density can be locally\nsuppressed, while fast circulation of a ring-shaped superflow around the area\nof suppressed density is maintained. Thus a giant vortex core comprising 7 to\n60 phase singularities is formed. The giant core is only metastable, and it\nwill refill with distinguishable single vortices after many rotation cycles.\nThe surprisingly long lifetime of the core can be attributed to the influence\nof strong Coriolis forces in the condensate. In addition we have been able to\nfollow the precession of off-center giant vortices for more than 20 cycles."
    },
    {
        "anchor": "Monte-Carlo simulation of string-like colloidal assembly: We study structural phase transition of polymer-grafted colloidal particles\nby Monte Carlo simulations on hard spherical particles. The interaction\npotential, which has a weak repulsive step outside the hard core, was validated\nwith use of the self-consistent field calculations. With this potential,\ncanonical Monte Carlo simulations have been carried out in two and three\ndimensions using the Metropolis algorithm. At low temperature and high density,\nwe find that the particles start to self-assemble and finally align in strings.\nBy analyzing the cluster size distribution and string length distribution, we\nconstruct a phase diagram and find that this string-like assembly is related to\nthe percolation phenomena. The average string length diverges in the region\nwhere the melting transition line and the percolation transition line cross,\nwhich is similar to Ising spin systems where the percolation transition line\nand the order-disorder line meet on the critical point.",
        "positive": "Chain extension of a confined polymer in steady shear flow: The growing importance of microfluidic and nanofluidic devices to the study\nof biological processes has highlighted the need to better understand how\nconfinement affects the behavior of polymers in flow. In this paper we explore\none aspect of this question by calculating the steady-state extension of a long\npolymer chain in a narrow capillary tube in the presence of simple shear. The\ncalculation is carried out within the framework of the Rouse-Zimm approach to\nchain dynamics, using a variant of a nonlinear elastic model to enforce finite\nextensibility. Under the assumption that the sole effect of the confining\nsurface is to modify the pre-averaged hydrodynamic interaction, we find that\nthe calculated fractional chain extension x is considerably smaller than its\nvalue in the bulk. Furthermore, the variation of x with a dimensionless shear\nrate (the Weissenberg number, Wi) is in good qualitative agreement with data\nfrom experiments on the flow-induced stretching of lambda- phage DNA near a\nnon-adsorbing glass surface."
    },
    {
        "anchor": "Phase behaviour of binary mixtures of diamagnetic colloidal platelets in\n  an external magnetic field: Using fundamental measure density functional theory we investigate\nparanematic-nematic and nematic-nematic phase coexistence in binary mixtures of\ncircular platelets with vanishing thicknesses. An external magnetic field\ninduces uniaxial alignment and acts on the platelets with a strength that is\ntaken to scale with the platelet area. At particle diameter ratio lambda=1.5\nthe system displays paranematic-nematic coexistence. For lambda=2, demixing\ninto two nematic states with different compositions also occurs, between an\nupper critical point and a paranematic-nematic-nematic triple point. Increasing\nthe field strength leads to shrinking of the coexistence regions. At high\nenough field strength a closed loop of immiscibility is induced and phase\ncoexistence vanishes at a double critical point above which the system is\nhomogeneously nematic. For lambda=2.5, besides paranematic-nematic coexistence,\nthere is nematic-nematic coexistence which persists and hence does not end in a\ncritical point. The partial orientational order parameters along the binodals\nvary strongly with composition and connect smoothly for each species when\nclosed loops of immiscibility are present in the corresponding phase diagram.",
        "positive": "Formation of protein-mediated tubes is governed by a snapthrough\n  transition: Plasma membrane tubes are ubiquitous in cellular membranes and in the\nmembranes of intracellular organelles. They play crucial roles in trafficking,\nion transport, and cellular motility. The formation of plasma membrane tubes\ncan be due to localized forces acting on the membrane or by curvature-induced\nby membrane-bound proteins. Here, we present a mathematical framework to model\ncylindrical tubular protrusions formed by proteins that induce anisotropic\nspontaneous curvature. Our analysis revealed that the tube radius depends on an\neffective tension that includes contributions from the bare membrane tension\nand the protein-induced curvature. We also found that the length of the tube\nundergoes an abrupt transition from a short, dome-shaped membrane to a long\ncylinder and this transition is characteristic of a snapthrough instability.\nFinally, we show that the snapthrough instability depends on the different\nparameters including coat area, bending modulus, and extent of protein-induced\ncurvature. Our findings have implications for tube formation due to BAR-domain\nproteins in processes such as endocytosis, t-tubule formation in myocytes, and\ncristae formation in mitochondria."
    },
    {
        "anchor": "Investigating the Settling Dynamics of Cohesive Silt Particles With\n  Particle-Resolving Simulations: The settling of cohesive sediment is ubiquitous in aquatic environments. In\nthe settling process, the silt particles show behaviors that are different from\nnon-cohesive particles due to the influence of inter-particle cohesive force.\nWhile it is a consensus that cohesive behaviors depend on the characteristics\nof sediment particles (e.g., Bond number, particle size distribution), little\nis known about the exact influence of these characteristics on the cohesive\nbehaviors. In the present work, three-dimensional settling process is\ninvestigated numerically by using CFD--DEM (Computational Fluid\nDynamics--Discrete Element Method). The inter-particle collision force, the van\nder Waals force, and the fluid--particle interaction forces are considered. The\nnumerical model is used to simulate the hindered settling process of silt based\non the experimental setup in the literature. The results obtained in the\nsimulations, including the structural densities of the beds, the characteristic\nlines, and the particle terminal velocity, are in good agreement with the\nexperimental observations in the literature. To the authors' knowledge, this is\nthe first time that the influences of non-dimensional Bond number and particle\npolydispersity on the structural densities of silt beds have been investigated\nseparately. The results demonstrate that the cohesive behavior of silt in the\nsettling process is attributed to both the cohesion among silt particles\nthemselves and the particle polydispersity. To guide to the macro-scale\nmodeling of cohesive silt sedimentation, the collision frequency functions\nobtained in the numerical simulations are also presented based on the\nmicromechanics of particles. The results obtained by using CFD--DEM indicate\nthat the binary collision theory over-estimated the particle collision\nfrequency in the flocculation process at high solid volume fraction.",
        "positive": "The double-layer of penetrable ions: an alternative route to charge\n  reversal: We investigate a double-layer of penetrable ions near a charged wall. We find\na new mechanism for charge reversal that occurs in the weak-coupling regime\nand, accordingly, the system is suitable for the mean-field analysis. The\npenetrability is achieved by smearing-out the ionic charge inside a sphere, so\nthere is no need to introduce non-electrostatic forces and the system in the\nlow coupling limit can be described by a modified version of the\nPoisson-Boltzmann equation. The predictions of the theory are compared with the\nMonte Carlo simulations."
    },
    {
        "anchor": "Controlled viscosity in dense granular materials: We experimentally investigate the fluidization of a granular material subject\nto mechanical vibrations by monitoring the angular velocity of a vane suspended\nin the medium and driven by an external motor. On increasing the frequency we\nobserve a re-entrant transition, as a jammed system first enters a fluidized\nstate, where the vane rotates with high constant velocity, and then returns to\na frictional state, where the vane velocity is much lower. While the\nfluidization frequency is material independent, the viscosity recovery\nfrequency shows a clear dependence on the material, that we rationalize by\nrelating this frequency to the balance between dissipative and inertial forces\nin the system. Molecular dynamics simulations well reproduce the experimental\ndata, confirming the suggested theoretical picture.",
        "positive": "Voltage distribution in a non-locally but globally electroneutral\n  confined electrolyte medium: applications for nanophysiology: The distribution of voltage in sub-micron cellular domains remains poorly\nunderstood. In neurons, the voltage results from the difference in ionic\nconcentrations which are continuously maintained by pumps and exchangers.\nHowever, it not clear how electro-neutrality could be maintained by an excess\nof fast moving positive ions that should be counter balanced by slow diffusing\nnegatively charged proteins. Using the theory of electro-diffusion, we study\nhere the voltage distribution in a generic domain, which consists of two\nconcentric disks (resp. ball) in two (resp. three) dimensions, where a negative\ncharge is fixed in the inner domain. When global but not local\nelectro-neutrality is maintained, we solve the Poisson-Nernst-Planck equation\nboth analytically and numerically in dimension 1 (flat) and 2 (cylindrical) and\nfound that the voltage changes considerably on a spatial scale which is much\nlarger than the Debye screening length, which assumes electro-neutrality. The\npresent result suggests that long-range voltage drop changes are expected in\nneuronal microcompartments, probably relevant to explain the activation of far\naway voltage-gated channels located on the surface."
    },
    {
        "anchor": "Theoretical Remarks on Cybotactic Clusters of Bent-Core Nematic Liquid\n  Crystals in 1D Settings: The bent-core liquid crystals (LCs) are highly regarded as the\nnext-generation materials for electro-optic devices. The nematic (N) phase of\nthese LCs possesses highly ordered smectic-like cybotactic clusters which are\npromising in terms of ferroelectric-like behaviour in the N phase itself. We\nhave studied a one-dimensional (1D) Landau-deGennes model of spatially\ninhomogeneous order parameters for the N phase of bent-core LCs. We investigate\nthe effects of spatial confinement and coupling (between these clusters and the\nsurrounding LC molecules) on the order parameters to model cluster formation in\nrecently reported experiments. The coupling is found to increase the cluster\norder parameter significantly, suggesting an enhancement in the cluster\nformation and could also predict a possible transition to a phase with weak\nnematic-like ordering in the vicinity of nematic-isotropic transition upon\nappreciable increase of the coupling parameter {\\gamma}.",
        "positive": "Emergent Properties of Antiagglomerant Films Control Methane Transport:\n  Implications for Hydrate Management: The relation between collective properties and performance of\nantiagglomerants (AAs) used in hydrate management is handled using molecular\ndynamics simulations and enhanced sampling techniques. A thin film of AAs\nadsorbed at the interface between one flat sII methane hydrate substrate and a\nfluid hydrocarbon mixture containing methane and n-dodecane is studied. The AA\nconsidered is a surface-active compound with a complex hydrophilic head that\ncontains both amide and tertiary ammonium cation groups and hydrophobic tails.\nAt sufficiently high AA density, the interplay between the surfactant layer and\nthe liquid hydrocarbon excludes methane from the interfacial region. In this\nscenario, we combine metadynamics and umbrella sampling frameworks to study\naccurately the free-energy landscape and the equilibrium rates associated with\nthe transport of one methane molecule across the AA film. We observe that local\nconfigurational changes of the liquid hydrocarbon packed within the AA film are\nassociated with high free-energy barriers for methane transport. The time\nscales estimated for the transport of methane across the AA film can be, in\nsome cases, comparable to those reported in the literature for the growth of\nthe hydrates, suggesting that one possible mechanism by which AAs delay the\nformation of hydrate plugs could be providing a barrier to methane transport.\nConsidering the interplay between structural design and collective properties\nof AAs might be of relevance to improve their performance in flow assurance."
    },
    {
        "anchor": "Memory in 3D cyclically driven granular material: We perform experimental and numerical studies of a granular system under\ncyclic-compression to investigate reversibility and memory effects. We focus on\nthe quasi-static forcing of dense systems, which is most relevant to a wide\nrange of geophysical, industrial, and astrophysical problems. We find that\nsoft-sphere simulations with proper stiffness and friction quantitatively\nreproduce both the translational and rotational displacements of the grains. We\nthen utilize these simulations to demonstrate that such systems are capable of\nstoring the history of previous compressions. While both mean translational and\nrotational displacements encode such memory, the response is fundamentally\ndifferent for translations compared to rotations. For translational\ndisplacements, this memory of prior forcing depends on the coefficient of\nstatic inter-particle friction, but rotational memory is not altered by the\nlevel of friction.",
        "positive": "Temperature-sensitive Soft Microgels at Interfaces: Air-Water versus\n  Oil-Water: The formation of smart emulsions or foams whose stability can be controlled\non-demand by switching external parameters is of great interest for basic\nresearch and applications. An emerging group of smart stabilizers are\nmicrogels, which are nano- and micro-sized, three-dimensional polymer networks\nthat are swollen by a good solvent. In the last decades, the influence of\nvarious external stimuli on the two-dimensional phase behavior of microgels at\nair- and oil-water interfaces has been studied. However, the impact of the\ntop-phase itself has been barely considered. Here, we present data that\ndirectly address the influence of the top-phase on the microgel properties at\ninterfaces. The dimensions of pNIPAM microgels are measured after deposition\nfrom two interfaces, i.e., air- and decane-water. While the total in-plane size\nof the microgel increases with increasing interfacial tension, the portions or\nfractions of the microgels situated in the aqueous phase are not affected. We\ncorrelate the area microgels occupy to the surface tensions of the interfaces,\nwhich allows to estimate an elastic modulus. In comparison to nanoindentation\nmeasurements, we observe a larger elastic modulus for the microgels. By\ncombining compression, deposition, and visualization, we show that the\ntwo-dimensional phase behavior of the microgel monolayers is not altered,\nalthough the microgels have a larger total in-plane size at higher interfacial\ntension. A peer reviewed and extended version of this preprint and the\nelectronic supplementary information can be found under S.~Bochenek, A.~Scotti,\nW.~Richtering, \\textit{Soft Matter}, 2020, DOI: 10.1039/d0sm01774d."
    },
    {
        "anchor": "Extreme active matter at high densities: Extreme active matter, an assembly of self-propelled particles with large\npersistence time $\\tau_p$ and high P\\'eclet number, exhibits remarkable\nbehaviour at high densities. As $\\tau_p\\to 0$, the assembly undergoes a gradual\nslowing down of density relaxations, as one reduces the active propulsion force\n$f$, until at the glass transition, the relaxation times diverge. In the other\nlimit, $\\tau_p \\to \\infty$, the fluid jams on lowering $f$, at a critical\nthreshold $f^*(\\infty)$, with stresses concentrated along force-chains. As one\nmoves away from this jamming threshold, the force-chains dynamically remodel,\nand the lifetime of the force-balanced configurations diverges as one\napproaches $f^*(\\infty)$, by tuning $\\tau_p$. In between these limits, the\napproach to dynamical arrest at low $f$, goes through a phase characterised by\nintermittency in the kinetic energy. This intermittency is a consequence of\nlong periods of jamming followed by bursts of plastic yielding associated with\nEshelby deformations, akin to the response of dense amorphous solids to an\nexternally imposed shear. The frequency of these plastic bursts increases as\none moves towards the intermittent phase-fluid boundary, where the correlated\nplastic events result in large scale vorticity and turbulence. Dense extreme\nactive matter brings together the physics of glass, jamming, plasticity and\nturbulence, in a new state of driven classical matter.",
        "positive": "Anomalous elasticity of cellular tissue vertex model: Vertex Models, as used to describe cellular tissue, have an energy controlled\nby deviations of each cell area and perimeter from target values. The\nconstrained nonlinear relation between area and perimeter leads to new\nmechanical response. Here we provide a mean-field treatment of a highly\nsimplified model: a uniform network of regular polygons with no topological\nrearrangements. Since all polygons deform in the same way, we only need to\nanalyze the ground states and the response to deformations of a single polygon\n(cell). The model exhibits the known transition between a fluid/compatible\nstate, where the cell can accommodate both target area and perimeter, and a\nrigid/incompatible state. %The rigid solid-like state has a single gapped\nground state. We calculate and measure the mechanical resistance to various\ndeformation protocols and discover that at the onset of rigidity, where a\nsingle zero-energy ground-state exists, %We show that in the incompatible\nstate, where a single frustrated ground-state exists, linear elasticity fails\nto describe the mechanical response to even infinitesimal deformations. In\nparticular we identify a breakdown of reciprocity expressed via different\nmoduli for compressive and tensile loads, implying non-analyticity of the\nenergy functional. We give a pictorial representation in configuration space\nthat reveals that the complex elastic response of the Vertex Model arises from\nthe presence of two distinct sets of reference states (associated with target\narea and target perimeter)."
    },
    {
        "anchor": "Coarse-graining the vertex model and its response to shear: Tissue dynamics and collective cell motion are crucial biological processes.\nTheir biological machinery is mostly known, and simulation models such as the\n\"active vertex model\" (AVM) exist and yield reasonable agreement with\nexperimental observations like tissue fluidization or fingering. However, a\ngood and well-founded continuum description for tissues remains to be\ndeveloped. In this work we derive a macroscopic description for a\ntwo-dimensional cell monolayer by coarse-graining the vertex model through the\nPoisson bracket approach. We obtain equations for cell density, velocity and\nthe cellular shape tensor. We then study the homogeneous steady states, their\nstability (which coincides with thermodynamic stability), and especially their\nbehavior under an externally applied shear. Our results contribute to elucidate\nthe interplay between flow and cellular shape. The obtained macroscopic\nequations present a good starting point for adding cell motion, morphogenetic\nand other biologically relevant processes.",
        "positive": "Bottom-Up Approach to Explore Alpha-Amylase Assisted Membrane\n  Remodelling: Soluble alpha-amylases play an important role in the catabolism of\npolysaccharides. In this work, we show that the enzyme can interact with the\nlipid membrane and further alter its mechanical properties. Vesicle fluctuation\nspectroscopy is used for quantitative measurement of the membrane bending\nrigidity of phosphatidylcholines lipid vesicles from the shape fluctuation\nbased on the whole contour of Giant Unilamellar Vesicles (GUVs). The bending\nrigidity of the lipid vesicles of\n1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine in water increases\nsignificantly with the presence of 0.14 micromolar alpha-amylase in the\nexterior solution. However, as the concentration increases above 1 micromolar,\nthe bending rigidity decreases but remains higher than estimated without the\nprotein. Contact between the alpha-amylase in the outer solution and the outer\nleaflet leads to spontaneous membrane curvature and the corresponding\nmorphological changes of the GUVs. The presence of outbuds directly\ndemonstrates that AA has a preferable interaction with the membrane, giving a\npositive spontaneous curvature of $C_0 \\leq 0.05 \\ \\mu \\rm{m}^{-1}$ at $18 \\\n\\mu$M $(\\approx$ 1 mg/ml) of AA concentration. Above 1 mg/ml of AA\nconcentration the shape of GUVs collapse completely suggesting a highly\nconvoluted state."
    },
    {
        "anchor": "Adapting the Teubner reciprocal relations for stokeslet objects: Self-propelled colloidal swimmers move by pushing the adjacent fluid\nbackwards. The resulting motion of an asymmetric body depends on the profile of\npushing velocity over its surface. We describe a method of predicting the\nmotion arising from arbitrary velocity profiles over a given body shape, using\na discrete-source \"stokeslet\" representation. The net velocity and angular\nvelocity is a sum of contributions from each point on the surface. The\ncontributions from a given point depend only on the shape. We give a numerical\nmethod to find these contributions in terms of the stokeslet positions defining\nthe shape. Each contribution is determined by linear operations on the Oseen\ninteraction matrix between pairs of stokeslets. We first adapt the Lorentz\nReciprocal Theorem to discrete sources. We then use the theorem to implement\nthe method of Teubner[1] to determine electrophoretic mobilities of\nnonuniformly charged bodies.",
        "positive": "Corporate Default Behavior: A Simple Stochastic Model: We compare observed corporate cumulative default probabilities to those\ncalculated using a stochastic model based on an extension of the work of Black\nand Cox and find that corporations default as if via diffusive dynamics. The\nmodel, based on a contingent-claims analysis of corporate capital structure, is\neasily calibrated with readily available historical default probabilities and\nfits observed default data published by Standard and Poor's. Applying this\nmodel to the Standard and Poor's default data we find that the difference in\ndefault behavior between credit ratings can be explained largely by a single\nvariable: the \"distance to default\" at the time the rating is given. The\nability to represent observed default behavior by a single analytic expression\nand to differentiate credit-rating-dependent default behavior with a single\nvariable recommends this model for a variety of risk management applications\nincluding the mapping of bank default experience to public credit ratings."
    },
    {
        "anchor": "Correlation of the fragility of metallic liquids with the high\n  temperature structure, volume, and cohesive energy: The thermal expansion coefficients, structure factors, and viscosities of\ntwenty-five equilibrium and supercooled metallic liquids have been measured\nusing an electrostatic levitation (ESL) facility. The structure factor was\nmeasured at the Advanced Photon Source, Argonne, using the ESL. A clear\nconnection between liquid fragility and structural and volumetric changes at\nhigh temperatures is established; the observed changes are larger for the more\nfragile liquids. It is also demonstrated that the fragility of metallic liquids\nis determined to a large extent by the cohesive energy and is, therefore,\npredictable. These results are expected to provide useful guidance in the\nfuture design of metallic glasses.",
        "positive": "Intermittent transport of bacterial chromosomal loci: The short-time dynamics of bacterial chromosomal loci is a mixture of\nsubdiffusive and active motion, in the form of rapid relocations with\nnear-ballistic dynamics. While previous work has shown that such rapid motions\nare ubiquitous, we still have little grasp on their physical nature, and no\npositive model is available that describes them. Here, we propose a minimal\ntheoretical model for loci movements as a fractional Brownian motion subject to\na constant but intermittent driving force, and compare simulations and\nanalytical calculations to data from high-resolution dynamic tracking in E.\ncoli. This analysis yields the characteristic time scales for intermittency.\nFinally, we discuss the possible shortcomings of this model, and show that an\nincrease in the effective local noise felt by the chromosome associates to the\nactive relocations."
    },
    {
        "anchor": "DNA capture into the ClyA nanopore: diffusion-limited versus\n  reaction-limited processes: The capture and translocation of biomolecules through nanometer-scale pores\nare processes with a potential large number of applications, and hence they\nhave been intensively studied in the recent years. The aim of this paper is to\nreview existing models of the capture process by a nanopore, together with some\nrecent experimental data of short single- and double-stranded DNA captured by\nCytolysin A (ClyA) nanopore. ClyA is a transmembrane protein of bacterial\norigin which has been recently engineered through site-specific mutations, to\nallow the translocation of double- and single-stranded DNA. A comparison\nbetween theoretical estimations and experiments suggests that for both cases\nthe capture is a reaction-limited process. This is corroborated by the observed\nsalt dependence of the capture rate, which we find to be in quantitative\nagreement with the theoretical predictions.",
        "positive": "Properties of layer-by-layer vector stochastic models of force\n  fluctuations in granular materials: We attempt to describe the stress distributions of granular packings using\nlattice-based layer-by-layer stochastic models that satisfy the constraints of\nforce and torque balance and non-tensile forces at each site. The inherent\nasymmetry in the layer-by-layer approach appears to lead to an asymmetric force\ndistribution, in disagreement with both experiments and general symmetry\nconsiderations. The vertical force component probability distribution is robust\nand in agreement with predictions of the scalar q model while the distribution\nof horizontal force components is qualitatively different and depends on the\ndetails of implementation."
    },
    {
        "anchor": "Brownian Dynamics simulations of aging colloidal gels: Colloidal gel aging is investigated using very long runs of brownian dynamics\nsimulations. The Asakura Oosawa description of the depletion interaction is\nused to model a simple colloid polymer mixture. Several regimes are identified\nduring gel formation. The Intermediate scattering function displays a double\ndecay characteristic of systems where some kinetic processes are frozen. The\n$\\beta$ relaxation at short times is explained in terms of the Krall-Weitz\nmodel for the decorelation due to the elastic modes present. The $\\alpha$\nrelaxation at long times is well described by a stretched exponential, showing\na wide spectrum of relaxation times for which the $q$ dependence is\n$\\tau_{\\alpha} = q^{-2.2}$, lower than for diffusion. For the shortest waiting\ntimes, a combination of two stretched exponentials is used, suggesting a\nbimodal distribution. The extracted relaxation times vary with waiting time as\n$\\tau_{\\alpha}=\\tau_w^{0.66}$, slower than the simple aging case. The real\nspace displacements are found to be strongly non-Gaussian, correlated in space\nand time. We were unable to find clear evidence that the gel aging was driven\nby internal stresses. Rather, we hypothesise that in this case of weakly\ninteracting gels, the aging behaviour arises due to the thermal diffusion of\nstrands, constrained by the percolating network which ruptures discontinuously.\nAlthough the mechanisms differ, the similarity of some of the results with the\naging of glasses is striking.",
        "positive": "Transient response and domain formation in electrically deforming liquid\n  crystal networks: Recently, Van der Kooij and co-workers recognised three distinct, transient\nregimes in the dynamics of electrically-deforming liquid crystal networks [Van\nder Kooij et al., Nat. Commun. 10, 1 (2019)]. Based on a Landau-theoretical\nframework, which encompasses spatially resolved information, we interpret these\nregimes: initially, the response is dominated by thermal noise, then the top of\nthe film expands, followed by a permeation of this response into the bulk. An\nimportant signature of this interpretation is a significant dependence of the\nregime time scales on film thickness, where we observe a clear\nthin-film-to-bulk transition. The point of transition coincides with the\nemergence of spatial inhomogeneities in the bulk, i.e., domain formation, and\nshould be avoided due to the less predictable steady-state expansion it gives\nrise to. Finally, we show that this domain formation can be suppressed by\ndecreasing the initial thickness of the film, and increasing the linear\ndimensions of the mesogens, or their orientational order when crosslinked into\nthe network, though this comes at the cost of the deformation magnitude. Our\nresults contribute to achieving finer control over how smart liquid crystal\nnetwork coatings are activated."
    },
    {
        "anchor": "Designing, Synthesizing and Modeling Active Fluids: We review recent advances in the design, synthesis, and modeling of active\nfluids. Active fluids have been at the center of many technological innovations\nand theoretical advances over the past two decades. Research on this new class\nof fluids has been inspired by the fascinating and remarkably efficient\nstrategies that biological systems employ, leading to the development of\nbiomimetic nano- and micro-machines and -swimmers. The review encompasses\nactive fluids on both the nano- and micro-scale. We start with examples of\nbiological active systems before we discuss how experimentalists leverage novel\npropulsion mechanisms to power nano- and micro-machines. We then examine how\nthe study of these far-from-equilibrium systems has prompted the development of\nnew simulation methods and theoretical models in nonquilibrium physics to\naccount for their mechanical, thermodynamic and emergent properties. Recent\nadvances in the field have paved the way for the design, synthesis, and\nmodeling of autonomous systems at the nano- and micro-scale and open the door\nto the development of soft matter robotics.",
        "positive": "Fluctuation interactions of colloidal particles: For like charged colloidal particles two mechanisms of attraction between\nthem survive when the interparticle distance is larger than the Debye screening\nlength. One of them is the conventional van der Waals attraction and the second\none is the attraction mechanism mediated by thermal fluctuations of particle\npositions. The latter is related to an effective variable mass (Euler mass) of\nthe particle produced by a fluid motion. The most stronger attraction potential\n(up to the value of temperature T) corresponds to a situation of uncharged\nparticles and a relatively large Debye screening length. In this case the third\nmechanism of attraction enters the game. It is mediated by thermal fluctuations\nof a fluid density."
    },
    {
        "anchor": "Symmetry-Breaking and Self-Sorting in Block Copolymer-based\n  Multicomponent Nanocomposites: Co-assembly of inorganic nanoparticles (NPs) and nanostructured polymer\nmatrix represents an intricate interplay of enthalpic or entropic forces.\nParticle size largely affects the phase behavior of the nanocomposite.\nTheoretical studies indicate that new morphologies would emerge when the\nparticles become comparable to the soft matrix's size, but this has rarely been\nsupported experimentally. By designing a multicomponent blend composed of NPs,\nblock copolymer-based supramolecules, and small molecules, a 3-D ordered\nlattice beyond the native BCP's morphology was recently reported when the\nparticle is larger than the microdomain of BCP. The blend can accommodate\nvarious formulation variables. In this contribution, when the particle size\nequals the microdomain size, a symmetry-broken phase appears in a narrow range\nof particle sizes and compositions, which we named the \"train track\" structure.\nIn this phase, the NPs aligned into a 3-D hexagonal lattice and packed\nasymmetrically along the c axis, making the projection of the ac and the bc\nplane resemble train tracks. Computation studies show that the broken symmetry\nreduces the polymer chain deformation and stabilizes the metastable hexagonally\nperforated lamellar morphology. Given the mobility of the multicomponent blend,\nthe system shows a self-sorting behavior: segregating into two macroscopic\nphases with different nanostructures based on only a few nanometers NP size\ndifferences. Smaller NPs form \"train track\" morphology, while larger NPs form\n\"simple hexagon\" structure, where the NPs take a symmetric hexagonal\narrangement. Detailed structural evolution and simulation studies confirm the\nsystematic-wide cooperativity across different components, indicating the\nstrong self-regulation of the multicomponent system.",
        "positive": "Mode-coupling theory of the stress-tensor autocorrelation function of a\n  dense binary fluid mixture: We present a generalized mode-coupling theory for a dense binary fluid\nmixture. The theory is used to calculate molecular-scale renormalizations to\nthe stress-tensor autocorrelation function (STAF) and to the long-wavelength\nzero-frequency shear viscosity. As in the case of a dense simple fluid, we find\nthat the STAF appears to decay as $t^{-3/2}$ over an intermediate range of\ntime. The coefficient of this long-time tail is more than two orders of\nmagnitude larger than that obtained from conventional mode-coupling theory. Our\nstudy focuses on the effect of compositional disorder on the decay of the STAF\nin a dense mixture."
    },
    {
        "anchor": "Colloidal Dynamics on a Choreographic Time Crystal: A choreographic time crystal is a dynamic lattice structure in which the\npoints comprising the lattice move in a coordinated fashion. These structures\nwere initially proposed for understanding the motion of synchronized satellite\nswarms. Using simulations we examine colloids interacting with a choreographic\ncrystal consisting of traps that could be created optically. As a function of\nthe trap strength, speed, and colloidal filling fraction, we identify a series\nof phases including states where the colloids organize into a dynamic chiral\nloop lattice as well as a frustrated induced liquid state and a choreographic\nlattice state. We show that transitions between these states can be understood\nin terms of vertex frustration effects that occur during a certain portion of\nthe choreographic cycle. Our results can be generalized to a broader class of\nsystems of particles coupled to choreographic structures, such as vortices,\nions, cold atoms, and soft matter systems.",
        "positive": "Designing convex repulsive pair potentials that favor assembly of kagome\n  and snub square lattices: Building on a recently introduced inverse strategy, isotropic and convex\nrepulsive pair potentials were designed that favor assembly of particles into\nkagome and equilateral snub square lattices. The former interactions were\nobtained by numerical solution of a variational problem that maximizes the\nrange of density for which the ground state of the potential is the kagome\nlattice. Similar optimizations targeting the snub square lattice were also\ncarried out, employing a constraint that required a minimum chemical potential\nadvantage of the target over select competing structures. This constraint\nhelped discover isotropic interactions that meaningfully favored the snub\nsquare lattice as the ground state structure despite the asymmetric spatial\ndistribution of particles in its coordination shells and the presence of\ntightly competing structures. Consistent with earlier published results\n[Pi\\~neros et al. J. Chem. Phys. 144, 084502 (2016)], enforcement of greater\nchemical potential advantages for the target lattice in the interaction\noptimization led to assemblies with enhanced thermal stability."
    },
    {
        "anchor": "Temperatures in Grains and Plasma: Grains are widely assumed to be characterized by a single temperature --\nderived either from the configurational entropy, or employing the kinetic\ntheory. Yet granular media do have two temperatures, $T_g$ and $T$, pertaining\nto the grains and atoms. It is argued here that a two-temperature plasma yields\na more useful analogy for grains than a molecular gas: (1)~Irreversible\ncollisions also occur in plasma, to reach the equilibrium of equal temperature.\n(2)~The plasma energy is not linear in the two temperatures; it is quadratic in\nthe temperature difference, minimal at equilibrium. Both points have valid\nanalogues in grains, yielding useful insights.",
        "positive": "Hyperbranched DNA clusters: Taking advantage of the base-pairing specificity and tunability of DNA\ninteractions, we investigate the spontaneous formation of hyperbranched\nclusters starting from purposely designed DNA tetravalent nanostar monomers,\nencoding in their four sticky-ends the desired binding rules. Specifically, we\ncombine molecular dynamics simulations and Dynamic Light Scattering experiments\nto follow the aggregation process of the DNA nanostars at different\nconcentrations and temperatures. At odd with the Flory-Stockmayer predictions,\nwe find that, even when all possible bonds are formed, the system does not\nreach percolation due to the presence of intracluster bonds. We present an\nextension of the Flory-Stockmayer theory that properly describes the numerical\nand the experimental results."
    },
    {
        "anchor": "Polyelectrolyte-induced peeling of charged multilamellar vesicles: We study mixtures of charged surfactants, which alone in solution form uni-\nand multilamellar vesicles, and oppositely charged polyelectrolytes (PEs). The\nphase behavior is investigated at fixed surfactant concentration as a function\nof the PE-to-surfactant charge ratio $x$. We find that, for $x>0$, aggregates\nform. Light microscopy and X-ray scattering experiments show that the\nisoelectric point plays a crucial role since the morphology and the microscopic\nstructure of the aggregates are different before ($x\\leq1$) and after the\nisoelectric point ($x>1$). To better understand the dynamics for the formation\nof PE/surfactant complexes, we perform light microscopy experiments where we\nfollow in real-time the effect of a PE solution on one multilamellar vesicle\n(MLV). We find that the PE induces a peeling of the bilayers of the MLV one by\none. The peeling is accompanied by strong shape fluctuations of the MLV and\nleads ultimately to a pile of small aggregates. This novel phenomenon is\nanalyzed in detail and discussed in terms of PE-induced tension, and pore\nformation and growth in a surfactant bilayer.",
        "positive": "Collapse and folding of pressurized rings in two dimensions: Hydrostatically pressurized circular rings confined to two dimensions (or\ncylinders constrained to have only z-independent deformations) undergo Euler\ntype buckling when the outside pressure exceeds a critical value. We perform a\nstability analysis of rings with arc-length dependent bending moduli and\ndetermine how weakened bending modulus segments affect the buckling critical\npressure. Rings with a 4-fold symmetric modulation are particularly susceptible\nto collapse. In addition we study the initial post-buckling stages of the\npressurized rings to determine possible ring folding patterns."
    },
    {
        "anchor": "Time evolution of dynamic propensity in a model glass former. The\n  interplay between structure and dynamics: By means of the isoconfigurational method we calculate the change in the\npropensity for motion that the structure of a glass-forming system experiences\nduring its relaxation dynamics. The relaxation of such a system has been\ndemonstrated to evolve by means of rapid crossings between metabasins of its\npotential energy surface (a metabasin being a group of mutually similar,\nclosely related structures which differ markedly from other metabasins), as\ncollectively relaxing units (d-clusters) take place. We now show that the\nspatial distribution of propensity in the system does not change significantly\nuntil one of these d-clusters takes place. However, the occurrence of a\nd-cluster clearly de-correlates the propensity of the particles, thus ending up\nwith the dynamical influence of the structural features proper of the local\nmetabasin. We also show an important match between particles that participate\nin d-clusters and that which show high changes in their propensity.",
        "positive": "Modeling hydrodynamic interactions in soft materials with multiparticle\n  collision dynamics: Multiparticle collision dynamics (MPCD) is a flexible and robust mesoscale\ncomputational technique for simulating solvent-mediated hydrodynamic\ninteractions in soft materials. Here, we provide a critical overview of the\nMPCD method and summarize its current strengths and limitations. The\ncapabilities of the method are highlighted by reviewing its recent applications\nto simulate diverse phenomena, ranging from the flow of complex fluids and\nthermo-osmotic transport to bacterial swimming and active particle\nself-assembly. We also discuss outstanding challenges and emerging\nmethodological developments that are expected to greatly expand the\napplicability of MPCD to other systems of technological importance."
    },
    {
        "anchor": "Mean-field microrheology of a very soft colloidal suspension: inertia\n  induces shear-thickening: Colloidal suspensions have a rich rheology and can exhibit shear-thinning as\nwell as shear-thickening. Numerical simulations recently suggested that\nshear-thickening may be attributed to the inertia of the colloids, besides the\nhydrodynamic interactions between them. Here, we consider the ideal limit of a\ndense bath of soft colloids following an underdamped Langevin dynamics. We use\na mean-field equation for the colloidal density to get an analytical expression\nof the drag force felt by a probe pulled at constant velocity through the\nsuspension. Our results show that inertia can indeed induce shear-thickening by\nallowing density waves to propagate through the suspension.",
        "positive": "Behavior of Supercooled Aqueous Solutions Stemming from Hidden\n  Liquid-Liquid Transition in Water: A popular hypothesis that explains the anomalies of supercooled water is the\nexistence of a metastable liquid-liquid transition hidden below the line of\nhomogeneous nucleation. If this transition exists and if it is terminated by a\ncritical point, the addition of a solute should generate a line of\nliquid-liquid critical points emanating from the critical point of pure\nmetastable water. We have analyzed thermodynamic consequences of this scenario.\nIn particular, we consider the behavior of two systems, H2O-NaCl and\nH2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous\nsolutions of NaCl, as reported by Archer and Carter, to be consistent with the\npresence of the metastable liquid-liquid transition. We suggest an\ninterpretation of the liquid-liquid transition in aqueous solutions of\nglycerol, recently observed by Murata and Tanaka, elucidating the non-conserved\nnature of the order parameter, its coupling with density and concentration, and\nthe peculiarity of \"spinodal decomposition without phase separation\". We also\nshow how the shape of the critical line in a solution controls the difference\nin concentration of the coexisting liquid phases."
    },
    {
        "anchor": "Annealing a Magnetic Cactus into Phyllotaxis: The appearance of mathematical regularities in the disposition of leaves on a\nstem, scales on a pine-cone and spines on a cactus has puzzled scholars for\nmillennia; similar so-called phyllotactic patterns are seen in self-organized\ngrowth, polypeptides, convection, magnetic flux lattices and ion beams. Levitov\nshowed that a cylindrical lattice of repulsive particles can reproduce\nphyllotaxis under the (unproved) assumption that minimum of energy would be\nachieved by 2-D Bravais lattices. Here we provide experimental and numerical\nevidence that the Phyllotactic lattice is actually a ground state. When\nmechanically annealed, our experimental \"magnetic cactus\" precisely reproduces\nbotanical phyllotaxis, along with domain boundaries (called transitions in\nBotany) between different phyllotactic patterns. We employ a structural genetic\nalgorithm to explore the more general axially unconstrained case, which reveals\nmultijugate (multiple spirals) as well as monojugate (single spiral)\nphyllotaxis.",
        "positive": "Long-range interactions between membrane inclusions: Electric field\n  induced giant amplification of the pairwise potential: The aim of this work is to revisit the phenomenological theory of the\ninteraction between membrane inclusions, mediated by the membrane fluctuations.\nWe consider the case where the inclusions are separated by distances larger\nthan their characteristic size. Within our macroscopic approach a physical\nnature of such inclusions is not essential, however we have always in mind two\nprototypes of such inclusions: proteins and RNA macromolecules. Because the\ninteraction is driven by the membrane fluctuations, and the coupling between\ninclusions and the membrane, it is possible to change the interaction potential\nby external actions affecting these factors. As an example of such external\naction we consider an electric field. Under external electric field (both dc or\nac), we propose a new coupling mechanism between inclusions possessing dipole\nmoments (as it is the case for most protein macromolecules) and the membrane.\nWe found, quite unexpected and presumably for the first time, that the new\ncoupling mechanism yields to giant enhancement of the pairwise potential of the\ninclusions. This result opens up a way to handle purposefully the interaction\nenergy, and as well to test of the theory set forth in our article."
    },
    {
        "anchor": "Coalescence of Low-Viscosity Fluids in Air: An electrical method is used to study the early stages of coalescence of two\nlow-viscosity drops. A drop of aqueous NaCl solution is suspended in air above\na second drop of the same solution which is grown until the drops touch. At\nthat point a rapidly widening bridge forms between them. By measuring the\nresistance and capacitance of the system during this coalescence event, one can\nobtain information about the time dependence of the characteristic bridge\nradius and its characteristic height. At early times, a new asymptotic regime\nis observed that is inconsistent with previous theoretical predictions. The\nmeasurements at several drop radii and approach velocities are consistent with\na model in which the two liquids coalesce with a slightly deformed interface.",
        "positive": "Active viscoelastic nematics with partial degree of order: Continuum models of active nematic gels have proved successful to describe a\nnumber of biological systems consisting of a population of rodlike motile\nsubunits in a fluid environment. However, in order to get a thorough\nunderstanding of the collective processes underlying the behaviour of active\nbiosystems, the theoretical underpinnings of these models still need to be\ncritically examined. To this end, we derive a minimal model based on a nematic\nelastomer energy, where the key parameters have a simple physical\ninterpretation and the irreversible nature of activity emerges clearly. The\ninterplay between viscoelastic material response and active dynamics of the\nmicroscopic constituents is accounted for by material remodelling. Partial\ndegree of order and defect dynamics is included as a result of the kinematic\ncoupling between the nematic elastomer shape-tensor and the orientational\nordering tensor $\\bQ$. In a simple one-dimensional channel geometry, we use\nlinear stability analysis to show that even in the isotropic phase the\ninteraction between flow-induced local nematic order and activity results in a\nspontaneous flow of particles."
    },
    {
        "anchor": "Shear thickening, frictionless and frictional rheologies in non-Brownian\n  suspensions: Particles suspended in a Newtonian fluid raise the viscosity and also\ngenerally give rise to a shear-rate dependent rheology. In particular,\npronounced shear thickening may be observed at large solid volume fractions. In\na recent article (R. Seto, R. Mari, J. F. Morris, and M. M. Denn., Phys. Rev.\nLett., 111:218301, 2013) we have considered the minimum set of components to\nreproduce the experimentally observed shear thickening behavior, including\nDiscontinuous Shear Thickening (DST). We have found frictional contact forces\nto be essential, and were able to reproduce the experimental behavior by a\nsimulation including this physical ingredient along with viscous lubrication.\nIn the present article, we thoroughly investigate the effect of friction and\nexpress it in the framework of the jamming transition. The viscosity divergence\nat the jamming transition has been a well known phenomenon in suspension\nrheology, as reflected in many empirical laws for the viscosity. Friction can\naffect this divergence, and in particular the jamming packing fraction is\nreduced if particles are frictional. Within the physical description proposed\nhere, shear thickening is a direct consequence of this effect: as the shear\nrate increases, friction is increasingly incorporated as more contacts form,\nleading to a transition from a mostly frictionless to a mostly frictional\nrheology. This result is significant because it shifts the emphasis from\nlubrication hydrodynamics and detailed microscopic interactions to geometry and\nsteric constraints close to the jamming transition.",
        "positive": "Structure, molecular dynamics, and stress in a linear polymer under\n  dynamic strain: The structural properties of a linear polymer and its evolution in time have\na strong bearing on its anisotropic stress response. The mean-square bond\nlength and mean bond angle are the critical parameters that influence the\ntime-varying stress developed in the polymer. The bond length distribution\nalong the chain is uniform without any abrupt changes at the ends. Among the\nexternally set parameters such as density, temperature, strain rate, and chain\nlength, the density as well as the chain length of the polymer have a\nsignificant effect on the stress. At high density values, changes in\nmean-square bond length dominates over changes in radius of gyration and\nend-to-end length. In other words, bond deformations dominate as opposed to\nchanges in size and shape. Also, there is a large change in the mean-square\nbond length that is reflected as a jump in the stress. Beyond a particular\nvalue of the chain length, $n = 50$, called the entanglement length,\nstress-response is found to have distinctly different behavior which we\nattribute to the entanglement effects. Short chain polymers more or less behave\nlike rigid molecules. There is no significant change in their internal\nstructure when loaded. Further, temperature and rate of loading have a very\nmild effect on the stress. Besides these new results, we can now explain well\nknown polymeric mechanical behavior under dynamic loading from the point of\nview of the evolution of the molecular dynamics and the derived structural\nproperties. This could possibly lead to polymer synthesis with desired\nmechanical behavior."
    },
    {
        "anchor": "Dynamical and structural signatures of the glass transition in emulsions: We investigate structural and dynamical properties of moderately polydisperse\nemulsions across an extended range of droplet volume fractions phgr,\nencompassing fluid and glassy states up to jamming. Combining experiments and\nsimulations, we show that when $\\phi$ approaches the glass transition volume\nfraction ${{\\phi}_{g}}$ , dynamical heterogeneities and amorphous order arise\nwithin the emulsion. In particular, we find an increasing number of clusters of\nparticles having five-fold symmetry (i.e. the so-called locally favoured\nstructures, LFS) as $\\phi$ approaches ${{\\phi}_{g}}$ , saturating to a roughly\nconstant value in the glassy regime. However, contrary to previous studies, we\ndo not observe a corresponding growth of medium-range crystalline order;\ninstead, the emergence of LFS is decoupled from the appearance of more ordered\nregions in our system. We also find that the static correlation lengths\nassociated with the LFS and with the fastest particles can be successfully\nrelated to the relaxation time of the system. By contrast, this does not hold\nfor the length associated with the orientational order. Our study reveals the\nexistence of a link between dynamics and structure close to the glass\ntransition even in the absence of crystalline precursors or crystallization.\nFurthermore, the quantitative agreement between our confocal microscopy\nexperiments and Brownian dynamics simulations indicates that emulsions are and\nwill continue to be important model systems for the investigation of the glass\ntransition and beyond.",
        "positive": "Magnetostriction in the magneto-sensitive elastomers with\n  inhomogeneously magnetized particles: pairwise interaction approximation: We analyze the magnetostriction effect occurring in the magneto-sensitive\nelastomers (MSEs) containing inhomogeneously magnetized particles. As it was\nshown before, the expression for the interaction potential between two magnetic\nspheres, that accounts for their mutual inhomogeneous magnetization, can be\nobtained from the Laplace equation. We use this potential in the approximation\nformula form to construct magnetic energy of the sample in terms of the\npairwise interactions of the particles. We show that this form of magnetic\nenergy leads to the same demagnetizing factor as predicted by the continuum\nmechanics, confirming that only dipole-dipole magnetic interactions are\nimportant on a large scale. As the next step, we examine the role played by the\nparticles arrangement on the magnetostriction effect. We consider different\nspatial distributions of the magnetic particles: a uniform one, as well as\nseveral lattice-type distributions (SC, BCC, HCP and FCC arrangements). We show\nthat the particles arrangement affects significantly the magnetostriction\neffect if the separation between them became comparable with the particles'\ndimensions. We also show that, typically, this contribution to the\nmagnetostriction effect is of the opposite sign to the one related with the\ninitial elastomer shape. Finally, we calculate the magnetostriction effect\nusing the same interaction potential but expressed in a form of a series\nexpansion, qualitatively confirming the above findings."
    },
    {
        "anchor": "Derivation of coarse-grained potentials via multistate iterative\n  Boltzmann inversion: In this work, an extension to the standard iterative Boltzmann inversion\n(IBI) method to derive coarse-grained potentials is proposed. It is shown that\nthe inclusion of target data from multiple states yields a less state-dependent\npotential, and is thus better suited to simulate systems over a range of\nthermodynamic states than the standard IBI method. The inclusion of target data\nfrom multiple states forces the algorithm to sample regions of potential phase\nspace that match the radial distribution function at multiple state points,\nthus producing a derived potential that is more representative of the\nunderlying potential interactions. It is shown that the algorithm is able to\nconverge to the true potential for a system where the underlying potential is\nknown. It is also shown that potentials derived via the proposed method better\npredict the behavior of n-alkane chains than those derived via the standard\nmethod. Additionally, through the examination of alkane monolayers, it is shown\nthat the relative weight given to each state in the fitting procedure can\nimpact bulk system properties, allowing the potentials to be further tuned in\norder to match the properties of reference atomistic and/or experimental\nsystems.",
        "positive": "Droplet absorption and spreading into thin layers of polymer hydrogels: From biological tissues to layers of paint, macroscopic non-porous materials\nwith the capacity to swell when brought in contact with an appropriate solvent\nare ubiquitous. Here, we study experimentally and theoretically one of the\nconceptually simplest of such systems, the swelling of a thin hydrogel layer by\na single water drop. Using a bespoke experimental setup, we observe fast\nabsorption leading to a radially spreading axisymmetric blister. Employing a\nlinear poroelastic framework and thin-layer scalings, we develop a non-linear\none-dimensional diffusion equation for the evolution of the blister height\nprofile, which agrees well with experimental observations."
    },
    {
        "anchor": "Pressure-sensitive ion conduction in a conical channel: optimal pressure\n  and geometry: Using both analytic and numerical analyses of the Poisson-Nernst-Planck\nequations we theoretically investigate the electric conductivity of a conical\nchannel, which in accordance with recent experiments exhibits a strong\nnon-linear pressure dependence. This mechanosensitive diodic behavior stems\nfrom the pressure-sensitive build-up or depletion of salt in the pore. From our\nanalytic results we find that the optimal geometry for this diodic behavior\nstrongly depends on the flow rate, the ideal ratio of tip-to-base-radii being\nequal to 0.22 at zero flow. With increased flow this optimal ratio becomes\nsmaller and simultaneously the diodic performance becomes weaker. Consequently\nan optimal diode is obtained at zero-flow, which is realized by applying a\npressure drop that is proportional to the applied potential and to the inverse\nsquare of the tip radius thereby countering electro-osmotic flow. When the\napplied pressure deviates from this ideal pressure drop the diodic performance\nfalls sharply, explaining the dramatic mechanosensitivity observed in\nexperiments.",
        "positive": "The role of internal chain dynamics on the rupture kinetics of adhesive\n  contacts: We study the forced rupture of adhesive contacts between monomers that are\nnot covalently linked in a Rouse chain. When the applied force ($f$) to the\nchain end is less than the critical force for rupture ($f_c$), the {\\it\nreversible} rupture process is coupled to the internal Rouse modes. If\n$f/f_{c}$$>$1 the rupture is {\\it irreversible}. In both limits, the\nnon-exponential distribution of contact lifetimes, which depends sensitively on\nthe location of the contact, follows the double-exponential (Gumbel)\ndistribution. When two contacts are well separated along the chain, the rate\nlimiting step in the {\\it sequential} rupture kinetics is the disruption of the\ncontact that is in the chain interior. If the two contacts are close to each\nother, they cooperate to sustain the stress, which results in an\n``all-or-none'' transition."
    },
    {
        "anchor": "Exotic fluids and crystals of soft polymeric colloids: We discuss recent developments and present new findings in the colloidal\ndescription of soft polymeric macromolecular aggregates. For various\nmacromolecular architectures, such as linear chains, star polymers, dendrimers\nand polyelectrolyte stars, the effective interactions between suitably chosen\ncoordinates are shown to be ultrasoft, i.e., they either remain finite or\ndiverge very slowly at zero separation. As a consequence, the fluid phases have\nunusual characteristics, including anomalous pair correlations and mean-field\nlike thermodynamic behaviour. The solid phases can exhibit exotic, strongly\nanisotropic as well as open crystal structures. For example, the diamond and\nthe A15-phase are shown to be stable at sufficiently high concentrations.\nReentrant melting and clustering transitions are additional features displayed\nby such systems, resulting in phase diagrams with a very rich topology. We\nemphasise that many of these effects are fundamentally different from the usual\narchetypal hard sphere paradigm. Instead, we propose that these fluids fall\ninto the class of mean-field fluids.",
        "positive": "Non-Fickian Interdiffusion of Dynamically Asymmetric Species: A\n  Molecular Dynamics Study: We use Molecular Dynamics combined with Dissipative Particle Dynamics to\nconstruct a model of a binary mixture where the two species differ only in\ntheir dynamic properties (friction coefficients). For an asymmetric mixture of\nslow and fast particles we study the interdiffusion process. The relaxation of\nthe composition profile is investigated in terms of its Fourier coefficients.\nWhile for weak asymmetry we observe Fickian behavior, a strongly asymmetric\nsystem exhibits clear indications of anomalous diffusion, which occurs in a\ncrossover region between the Cases I (Fickian) and II (sharp front moving with\nconstant velocity), and is close to the Case II limit."
    },
    {
        "anchor": "Effect of Intra-molecular Disorder and Inter-molecular Electronic\n  Interactions on the Electronic Structure of Poly-p-Phenylene Vinylene (PPV): We investigate the role of intra-molecular conformational disorder and\ninter-molecular electronic interactions on the electronic structure of disorder\nclusters of poly-p-phenylene vinylene (PPV) oligomers. Classical molecular\ndynamics is used to determine probable molecular geometries, and\nfirst-principle density functional theory (DFT) calculations are used to\ndetermine electronic structure. Intra-molecular and inter-molecular effects are\ndisentangled by contrasting results for densely packed oligomer clusters with\nthose for ensembles of isolated oligomers with the same intra-molecular\ngeometries. We find that electron trap states are induced primarily by\nintra-molecular configuration disorder, while the hole trap states are\ngenerated primarily from inter-molecular electronic interactions.",
        "positive": "Bubble kinetics in a steady-state column of aqueous foam: We measure the liquid content, the bubble speeds, and the distribution of\nbubble sizes, in a vertical column of aqueous foam maintained in steady-state\nby continuous bubbling of gas into a surfactant solution. Nearly round bubbles\naccumulate at the solution/foam interface, and subsequently rise with constant\nspeed. Upon moving up the column, they become larger due to gas diffusion and\nmore polyhedral due to drainage. The size distribution is monodisperse near the\nbottom and polydisperse near the top, but there is an unexpected range of\nintermediate heights where it is bidisperse with small bubbles decorating the\njunctions between larger bubbles. We explain the evolution in both bidisperse\nand polydisperse regimes, using Laplace pressure differences and taking the\nliquid fraction profile as a given."
    },
    {
        "anchor": "Why Does the Rouse Model Works at Least Satisfactorily at Polymer\n  Molecular Masses M<M_c ?: Generalization of the Rouse model without any use of the postulates\nconcerning the Gaussian distribution of the vector connecting the ends of\nsegments is advanced. In the initial (in general, nonlinear) Langevin\nequations, self-averaging over continuous fragments of a macromolecule\nnaturally defines a linear term for the tagged chain, and this term differs\nfrom the entropy term of the classical Rouse model only by the numerical\ncoefficient. According to the inertia-free approximation, the initial decay\nrates of correlation functions for the normal modes are described by the Rouse\nmodel independently of the character of fluctuations of the vector connecting\nthe ends of the Kuhn segment. This statement is valid for any moment if the\ninitial Langevin equations are treated in terms of the approximation of dynamic\nself-consistency. Simulation of the Fraenkel chains by the method of Brownian\ndynamics shows that decay of autocorrelation functions of shortwave normal\nmodes is fairly described by the linearized equations for a given model of a\nchain and that the Rouse equation can be used for the longwave modes. The\nresults of this study make it possible to explain a marked difference between\nthe lengths of the Kuhn and Rouse segments that is estimated from static and\ndynamic experiments.",
        "positive": "Conductance of DNA molecules: Effects of decoherence and bonding: The influence of decoherence and bonding on the linear conductance of single\ndouble-stranded DNA molecules is examined by fitting a phenomenological\nstatistical model developed recently (EPJB {\\bf 68}, 237 (2009)) to\nexperimental results. The DNA molecule itself is described by a tight binding\nladder model with parameters obtained from published ab initio calculations\n(J.Am.Chem.Soc. {\\bf 127}, 14894 (2005)). The good agreement with the\nexperiments on sequence and length dependence gives a hint on the nature of\nconduction in DNA and at the same time provides a crucial test of the model."
    },
    {
        "anchor": "Scaling and dynamics of sphere and disk impact into granular media: Direct measurements of the acceleration of spheres and disks impacting\ngranular media reveal simple power law scalings along with complex dynamics\nwhich bear the signatures of both fluid and solid behavior. The penetration\ndepth scales linearly with impact velocity while the collision duration is\nconstant for sufficiently large impact velocity. Both quantities exhibit power\nlaw dependence on sphere diameter and density, and gravitational acceleration.\nThe acceleration during impact is characterized by two jumps: a rapid, velocity\ndependent increase upon initial contact and a similarly sharp, depth dependent\ndecrease as the impacting object comes to rest. Examining the measured forces\non the sphere in the vicinity of these features leads to a new experimentally\nbased granular force model for collision. We discuss our findings in the\ncontext of recently proposed phenomenological models that capture qualitative\ndynamical features of impact but fail both quantitatively and in their\ninability to capture significant acceleration fluctuations that occur during\npenetration and which depend on the impacted material.",
        "positive": "Kinetic theory for strong uniform shear flow of granular media at high\n  density: We discuss the uniform shear flow of a fluidized granular bed composed of\nmonodisperse Hertzian spheres. Considering high densities around the glass\ntransition density of inelastic Hertzian spheres, we report kinetic theory\nexpressions for the Newtonian viscosity as well as the Bagnold coefficient. We\ndiscuss the dependence of the transport coefficients on density and coefficient\nof restitution."
    },
    {
        "anchor": "Adsorption-active polydisperse brush with tunable molecular mass\n  distribution: Recently a novel class of responsive uncharged polymer brushes has been\nproposed [Klushin et al, J. Chem. Phys. 154, 074904 (2021)] where the\nbrush-forming chains have an affinity to the substrate. For sufficiently strong\nsurface interactions, a fraction of chains condenses into a near-surface layer,\nwhile the remaining ones form the outer brush with a reduced grafting density.\nThe dense layer and the more tenuous outer brush can be seen as coexisting\nmicrophases. The effective grafting density of the outer brush is controlled by\nthe adsorption strength and can be changed reversibly as a response to changes\nin environmental parameters.\n  In this paper we use numerical self-consistent field calculations and\ntheoretical considerations to study this phenomenon in polydisperse brushes.\nOur results reveal an unexpected effect: Although all chains are chemically\nidentical, shorter chains are adsorbed preferentially. Hence, with the increase\nin the surface affinity parameter, a reduction in the surface grafting density\nof the residual brush is accompanied by a change in the shape of its molecular\nmass distribution. In particular, an originally bidisperse brush can be\neffectively transformed into a nearly monodisperse one containing only the\nlonger chain fraction.",
        "positive": "Interface mediated interactions between particles -- a geometrical\n  approach: Particles bound to an interface interact because they deform its shape. The\nstresses that result are fully encoded in the geometry and described by a\ndivergence-free surface stress tensor. This stress tensor can be used to\nexpress the force on a particle as a line integral along any conveniently\nchosen closed contour that surrounds the particle. The resulting expression is\nexact (i.e., free of any \"smallness\" assumptions) and independent of the chosen\nsurface parametrization. Additional surface degrees of freedom, such as vector\nfields describing lipid tilt, are readily included in this formalism. As an\nillustration, we derive the exact force for several important surface\nHamiltonians in various symmetric two-particle configurations in terms of the\nmidplane geometry; its sign is evident in certain interesting limits.\nSpecializing to the linear regime, where the shape can be analytically\ndetermined, these general expressions yield force-distance relations, several\nof which have originally been derived by using an energy based approach."
    },
    {
        "anchor": "Polymer Crowding and Shape Distributions in Polymer-Nanoparticle\n  Mixtures: Macromolecular crowding can influence polymer shapes, which is important for\nunderstanding the thermodynamic stability of polymer solutions and the\nstructure and function of biopolymers (proteins, RNA, DNA) under confinement.\nWe explore the influence of nanoparticle crowding on polymer shapes via Monte\nCarlo simulations and free-volume theory of a coarse-grained model of\npolymer-nanoparticle mixtures. Exploiting the geometry of random walks, we\nmodel polymer coils as effective penetrable ellipsoids, whose shapes fluctuate\naccording to the probability distributions of the eigenvalues of the gyration\ntensor. Accounting for the entropic cost of a nanoparticle penetrating a larger\npolymer coil, we compute the crowding-induced shift in the shape distributions,\nradius of gyration, and asphericity of ideal polymers in a theta solvent. With\nincreased nanoparticle crowding, we find that polymers become more compact\n(smaller, more spherical), in agreement with predictions of free-volume theory.\nOur approach can be easily extended to nonideal polymers in good solvents and\nused to model conformations of biopolymers in crowded environments.",
        "positive": "Spontaneous flow states in active nematics: a unified picture: Continuum hydrodynamic models of active liquid crystals have been used to\ndescribe dynamic self-organising systems such as bacterial swarms and\ncytoskeletal gels. A key prediction of such models is the existence of\nself-stabilising kink states that spontaneously generate fluid flow in\nquasi-one dimensional channels. Using simple stability arguments and numerical\ncalculations we extend previous studies to give a complete characterisation of\nthe phase space for both contractile and extensile particles (ie pullers and\npushers) moving in a narrow channel as a function of their flow alignment\nproperties and initial orientation. This gives a framework for unifying many of\nthe results in the literature. We describe the response of the kink states to\nan imposed shear, and investigate how allowing the system to be polar modifies\nits dynamical behaviour."
    },
    {
        "anchor": "Confined photon modes with triangular symmetry in hexagonal\n  microcavities in 2D photonic Crystals: We present theoretical and experimental studies of the size and thickness\ndependencies of the optical emission spectra from microcavities with hexagonal\nshape in films of two-dimensional photonic crystal. A semiclassical plane-wave\nmodel, which takes into account the electrodynamic properties of quasi-2D\nplanar photonic microcavity, is developed to predict the eigenfrequencies of\nthe confined photon modes as a function of both the hexagon-cavity size and the\nfilm thickness. Modes with two different symmetries, triangular and hexagonal,\nare critically analyzed. It is shown that the model of confined photon modes\nwith triangular symmetry gives a better agreement between the predicted\neigenmodes and the observed resonances.",
        "positive": "Stoichiometry of Electrostatic Complexes Determined by Light Scattering: We report on the electrostatic complexation between oppositely charged\npolymers and inorganic nanoparticles investigated by static and dynamical light\nscattering. The nanoparticles put under scrutiny were citrate-coated\nnanocrystals of cerium oxide (CeO2, nanoceria), of iron oxide (Fe2O3,\nmaghemite) and of europium-doped yttrium vanadate (Eu:YVO4) with sizes in the\n10 nm range. For the polymers, we have used cationic-neutral diblock copolymers\n(poly(trimethylammonium ethylacrylate)-b-poly(acrylamide), hereafter referred\nto as PTEA-b-PAM) with different molecular weights. For the three colloidal\ndispersions, we show that the electrostatic complexation gives rise to the\nformation of stable nanoparticle clusters in the 100 nm range. The complexation\nwas monitored by systematic measurements of the scattering intensity versus X,\nthe mixing ratio between nanoparticles and polymers. For 5 nanoparticle/polymer\npairs, namely CeO2/PTEA5K-b-PAM30K, Fe2O3/PTEA5K-b-PAM30K,\nFe2O3/PTEA11K-b-PAM30K, Eu:YVO4/PTEA2K-b-PAM60K and Eu:YVO4/PTEA5K-b-PAM30K, we\nfound a unique behavior : the scattering intensity exhibits a sharp and\nprominent peak in the intermediate X-range. To account for this behavior, we\nhave developed a model which assumes that regardless of X, the mixed aggregates\nare formed at a fixed polymer-to-nanoparticle ratio. The agreement between the\nresults and the model is excellent on the 5 systems. Results at different\nmolecular weights suggest that the stoichiometry of the mixed aggregates is\ncontrolled by the electrostatic interactions between the opposite charges. The\nmodel allows to derive the molecular weight and the stoichiometry of the mixed\naggregates."
    },
    {
        "anchor": "Dynamics of inert spheres in active suspensions of micro-rotors: Inert particles suspended in active fluids of self-propelled particles are\nknown to often exhibit enhanced diffusion and novel coherent structures. Here\nwe numerically investigate the dynamical behavior and self-organization in a\nsystem consisting of passive and actively rotating spheres. The particles\ninteract through direct collisions and the fluid flows generated as they move.\nIn the absence of passive particles, three states emerge in a binary mixture of\nspinning spheres depending on particle fraction: a dilute gas-like state where\nthe rotors move chaotically, a phase-separated state where like-rotors move in\nlanes or vortices, and a jammed state where crystals continuously assemble,\nmelt and move (K. Yeo, E. Lushi, and P. M. Vlahovska, Phys. Rev. Lett. 114,\n188301 (2015)). Passive particles added to the rotor suspension modify the\nsystem dynamics and pattern formation: while states identified in the pure\nactive suspension still emerge, they occur at different densities and mixture\nproportions. The dynamical behavior of the inert particles is also\nnon-trivially dependent on the system composition.",
        "positive": "A field theoretic model for static friction: We present a field theoretic model for friction, where the friction\ncoefficient between two surfaces may be calculated based on elastic properties\nof the surfaces. We assume that the geometry of contact surface is not unusual.\nWe verify Amonton's laws to hold that friction force is proportional to the\nnormal load.This model gives the opportunity to calculate the static\ncoefficient of friction for a few cases, and show that it is in agreement with\nobserved values. Furthermore we show that the coefficient of static friction is\nindependent of apparent surface area in first approximation."
    },
    {
        "anchor": "Orientational Order in Disordered Colloidal Suspensions: Exploring structural order in disordered systems including liquids and\nglasses is an intriguing but challenging issue in condensed matter physics.\nHere we construct a new parameter based on the angular distribution function of\nparticles and show that this new orientational order has significantly higher\ncorrelation with dynamic heterogeneity compared to a translational parameter\nbased on the radial distribution functions in colloidal glasses. The gradual\ndevelopment of orientational and translational order in supercooled liquids\nshows that the higher correlation between orientational order and dynamics\ncomes from the onset of glass transition and the orientational order would\ndominate the glassy dynamics after a simple liquid is considerably supercooled.\nOur results suggest that orientational order reflects the formation of\namorphous order during glass transition while translational order is mainly a\nresult of density increase.",
        "positive": "Active polar flock with birth and death: We study a collection of self-propelled polar particles on a two-dimensional\nsubstrate with birth and death. We introduce a minimal lattice model for the\nsystem using active Ising spins, where each particle can have two possible\norientations. The activity is modeled as a biased movement of the particle\nalong its direction of orientation. The particles also align with their nearest\nneighbors using Metropolis Monte-Carlo algorithm. System shows a\ndisorder-to-order transition by tuning the temperature of the system.\nAdditionally, the birth and death of the particles is introduced through a\nbirth and death rate $\\gamma$. The system is studied near the disorder-to-order\ntransition. The nature of disorder-to-order transition shows a crossover from\nfirst order, discontinuous to continuous type as we tune $\\gamma$ from zero to\nfinite values. We also write the effective free energy of the local order\nparameter using renormalised mean field theory and it confirms the dependence\nof the nature of phase transition on the birth and death rate parameter."
    },
    {
        "anchor": "Localization of water monomers inside ice-like clusters: On the basis of the experimental data we suggest that water monomers could be\ntrapped in channels running through ice-like clusters in water. Our argument\nrelies on a simple model that describes the motion of a dipole particle inside\na channel in the presence of an electric field with linear gradient. The model\nadmits of both finite and infinite regimes of motion so that the finite one\ncould correspond to the particle being confined to a channel.",
        "positive": "An approximate JKR solution for a general contact, including rough\n  contacts: In the present note, we suggest a simple closed form approximate solution to\nthe adhesive contact problem under the so-called JKR regime. The derivation is\nbased on generalizing the original JKR energetic derivation assuming\ncalculation of the strain energy in adhesiveless contact, and unloading at\nconstant contact area. The underlying assumption is that the contact area\ndistributions are the same as under adhesiveless conditions (for an\nappropriately increased normal load), so that in general the stress intensity\nfactors will not be exactly equal at all contact edges. The solution is simply\nthat the indentation is D=D1-Sqrt(2w A'/P\") where w is surface energy, D1 is\nthe adhesiveless indentation, A' is the first derivative of contact area and P\"\nthe second derivative of the load with respect to indentation. The solution\nonly requires macroscopic quantities, and not very elaborate local\ndistributions, and is exact in many configurations like axisymmetric contacts.\nIt permits also an estimate of the full solution for elastic rough solids with\nGaussian multiple scales of roughness, which so far was lacking, using known\nadhesiveless simple results. The solution turns out to depend only on rms\namplitude and slopes of the surface, and in the fractal limit, slopes would\ngrow without limit, tends to the adhesiveless result - although in this limit\nthe JKR model is inappropriate. However, a more solid result is that the\nsolution would also go to adhesiveless result for large rms amplitude of\nroughness h_{rms}, irrespective of the small scale details, and in agreement\nwith common sense and previous models by the author."
    },
    {
        "anchor": "Annealing of single lamella nanoparticles of polyethylene: We study the change of the size and structure of freely suspended single\nlamella nanoparticles of polyethylene during thermal annealing in aqueous\nsolutions. Using small-angle x-ray scattering and cryogenic transmission\nelectron microscopy, it is shown that a doubling of the crystalline lamella\nsandwiched between two amorphous polymer layers is obtained by annealing the\nnanoparticles at 125 C. This thickening of the crystalline lamella can be\nunderstood in terms of an unlooping of polymer chains within a single\nnanoparticle. In addition a variation of the annealing temperature from 90 C to\n115 C demonstrates that the inverse of the crystalline lamellar thickness\nincreases linearly with the annealing temperatures leading to a\nrecrystallization line in a Gibbs-Thomson graph. Since the nanoparticles\nconsist of about only eight polymer chains, they can be considered as a ideal\ncandidates for the experimental realization of equilibrium polymer crystals.",
        "positive": "Dilation-invariant bending of elastic plates, and broken symmetry in\n  shells: We propose bending energies for isotropic elastic plates and shells. For a\nplate, we define and employ a surface tensor that symmetrically couples stretch\nand curvature such that any elastic energy density constructed from its\ninvariants is invariant under spatial dilations. This kinematic measure and its\ncorresponding isotropic quadratic energy resolve outstanding issues in thin\nstructure elasticity, including the natural extension of primitive bending\nstrains for straight rods to plates, the assurance of a moment linear in the\nbending measure, and the avoidance of induced mid-plane strains in response to\npure moments as found in some commonly used analytical plate models. Our\nanalysis also reveals that some other commonly used numerical models have the\nright invariance properties, although they lack full generality at quadratic\norder in stretch. We further extend our result to naturally-curved rods and\nshells, for which the pure stretching of a curved rest configuration breaks\ndilation invariance; the new shell bending measure we provide contrasts with\nprevious \\emph{ad hoc} postulated forms. The concept that unifies these\ntheories is not dilation invariance, but rather through-thickness uniformity of\nstrain as a definition of pure stretching deformations. Our results provide a\nclean basis for simple models of low-dimensional elastic systems, and should\nenable more accurate analytical probing of the structure of singularities in\nsheets and membranes."
    },
    {
        "anchor": "Flatness and Intrinsic Curvature of Linked-Ring Membranes: Recent experiments have elucidated the physical properties of kinetoplasts,\nwhich are chain-mail-like structures found in the mitochondria of trypanosome\nparasites formed from catenated DNA rings. Inspired by these studies, we use\nMonte Carlo simulations to examine the behavior of two-dimensional networks\n(\"membranes\") of linked rings. For simplicity, we consider only identical rings\nthat are circular and rigid and that form networks with a regular linking\nstructure. We find that the scaling of the eigenvalues of the shape tensor with\nmembrane size are consistent with the behavior of the flat phase observed in\nself-avoiding covalent membranes. Increasing ring thickness tends to swell the\nmembrane. Remarkably, unlike covalent membranes, the linked-ring membranes tend\nto form concave structures with an intrinsic curvature of entropic origin\nassociated with local excluded-volume interactions. The degree of concavity\nincreases with increasing ring thickness and is also affected by the type of\nlinking network. The relevance of the properties of linked-ring model membranes\nto those observed in kinetoplasts is discussed.",
        "positive": "Pushing off the walls: a mechanism of cell motility in confinement: We propose a novel mechanism of cell motility, which relies on the coupling\nof actin polymerization at the cell membrane to geometric confinement. We\nconsider a polymerizing viscoelastic cytoskeletal gel confined in a narrow\nchannel, and show analytically that spontaneous motion occurs. Interestingly,\nthis does not require specific adhesion with the channel walls, and yields\nvelocities potentially larger than the polymerization velocity. The contractile\nactivity of myosin motors is not necessary to trigger motility in this\nmechanism, but is shown quantitatively to increase the velocity. Our model\nqualitatively accounts for recent experiments which show that cells without\nspecific adhesion proteins are motile only in confined environments while they\nare unable to move on a flat surface, and could help in understanding the\nmechanisms of cell migration in more complex confined geometries such as living\ntissues."
    },
    {
        "anchor": "Elasticity, stability, and quasi-oscillations of cell-cell junctions in\n  solid confluent epithelia: Macroscopic properties and shapes of biological tissues depend on the\nremodelling of cell-cell junctions at the microscopic scale. We propose a\ntheoretical framework that couples a vertex model of solid confluent tissues\nwith the dynamics describing generation of local force dipoles in the\njunctional actomyosin. Depending on the myosin-turnover rate, junctions either\npreserve stable length or collapse to initiate cell rearrangements. We find\nthat noise can amplify and sustain transient oscillations to the fixed point,\ngiving rise to quasi-periodic junctional dynamics. We also discover that\njunctional stability is affected by cell arrangements and junctional rest\ntensions, which may explain junctional collapse during convergence and\nextension in embryos.",
        "positive": "Dielectric response of thin water films: A thermodynamic perspective: The surface of a polar liquid presents a special environment for the\nsolvation and organization of charged solutes, which differ from bulk behaviors\nin important ways. These differences have motivated many attempts to understand\nelectrostatic response at aqueous interfaces in terms of a spatially varying\ndielectric permittivity, typically concluding that the dielectric constant of\ninterfacial water is significantly lower than in the bulk liquid. Such\nanalyses, however, are complicated by the potentially nonlocal nature of\ndielectric response over the short length scales of interfacial heterogeneity.\nHere we circumvent this problem for thin water films by adopting a\nthermodynamic approach. Using molecular simulations, we calculate the solvent's\ncontribution to the reversible work of charging a parallel plate capacitor. We\nfind good agreement with a simple dielectric continuum model that assumes bulk\ndielectric permittivity all the way up to the liquid's boundary, even for very\nthin ($\\sim 1$ nm) films. This comparison requires careful attention to the\nplacement of dielectric boundaries between liquid and vapor, which also\nresolves apparent discrepancies with dielectric imaging experiments."
    },
    {
        "anchor": "How to derive and parameterize effective potentials in colloid-polymer\n  mixtures: Polymer chains in colloid-polymer mixtures can be coarse-grained by replacing\nthem with single soft particles interacting via effective polymer-polymer and\npolymer-colloid pair potentials. Here we describe in detail how\nOrnstein-Zernike inversion techniques, originally developed for atomic and\nmolecular fluids, can be generalized to complex fluids and used to derive\neffective potentials from computer simulations on a microscopic level. In\nparticular, we consider polymer solutions for which we derive effective\npotentials between the centers of mass, and also between mid-points or\nend-points from simulations of self-avoiding walk polymers. In addition, we\nderive effective potentials for polymers near a hard wall or a hard sphere. We\nemphasize the importance of including both structural and thermodynamic\ninformation (through sum-rules) from the underlying simulations. In addition we\ndevelop a simple numerical scheme to optimize the parameterization of the\ndensity dependent polymer-polymer, polymer-wall and polymer-sphere potentials\nfor dilute and semi-dilute polymer densities, thus opening up the possibility\nof performing large-scale simulations of colloid-polymer mixtures. The methods\ndeveloped here should be applicable to a much wider range effective potentials\nin complex fluids.",
        "positive": "Effect of Particle Shape and Charge on Bulk Rheology of Nanoparticle\n  Suspensions: The rheology of nanoparticle suspensions for nanoparticles of various shapes\nwith equal mass is studied using molecular dynamics simulations. The\nequilibrium structure and the response to imposed shear are analyzed for\nsuspensions of spheres, rods, plates, and jacks in an explicit solvent for both\ncharged and uncharged nanoparticles. For the volume fraction studied,\n?$\\phi_{vf}=0.075$, the uncharged systems are all in their isotropic phase and\nthe viscosity is only weakly dependent on shape for spheres, rods, and plate\nwhereas for the jacks the viscosity is an order of magnitude larger than for\nthe other three shapes. The introduction of charge increases the viscosity for\nall four nanoparticle shapes with the increase being the largest for rods and\nplates. The presence of a repulsive charge between the particles decreases the\namount of stress reduction that can be achieved by particle reorientation."
    },
    {
        "anchor": "Impedance Matching in an Elastic Actuator: We optimize the performance of an elastic actuator consisting of an active\ncore in a host which performs mechanical work on a load. The system, initially\nwith localized elastic energy in the active component, relaxes and distributes\nenergy to the rest of the system. Using the linearized Mooney-Rivlin\nhyperelastic model in a cylindrical geometry and assuming the system to be\noverdamped, we show that the value of the Young's modulus of the impedance\nmatching host which maximizes the energy transfer from the active component to\nthe load is the geometric mean of Young's moduli of the active component and\nthe elastic load. This is similar to the classic results for impedance matching\nfor maximizing the transmittance of light propagating through dielectric media.",
        "positive": "Finite Size Effect on Correlation Functions of a Bose Gas in a Trap and\n  Destruction of the Order Parameter by Phase Fluctuations: The influence of the finite sizes on the coherent properties of 3D Bose\nsystems is considered. As is shown, the correlation functions of a Bose gas in\na trap have essential differences from analogous correlation functions in an\ninfinite system. Thus, the anomalous correlation function vanishes due to the\ndivergency of phase fluctuations which destruct the order parameter too. The\nnormal correlation function decays exponentially in time for sufficiently large\ntime interval."
    },
    {
        "anchor": "Effective macroion charge and stability of highly asymmetric\n  electrolytes at various salt conditions: We study electrostatic mechanisms of destabilization of highly asymmetric\nelectrolytes. For this purpose, we perform primitive model Monte Carlo\nsimulations of charged macroions immersed in multivalent salt solution. At low\nsalt concentration, the macroion effective charge is reduced due to multivalent\ncounterion adsorption. At high salt concentrations, the macroions become\novercharged so that their apparent charge has the opposite sign to the\nstoichiometric one. The inverted charge is growing up to a saturation value\nupon further increasing the salinity. The system remains stable at low as well\nas at very high salt concentrations. In the intermediate region, close to the\nmacroion isoelectric point, we observe macroion aggregation. The obtained phase\nbehaviour closely resembles polyelectrolyte-induced instability of colloidal\ndispersions.",
        "positive": "Dynamic Elastic Moduli in Magnetic Gels: Normal Modes and Linear\n  Response: In the perspective of developing smart hybrid materials with customized\nfeatures, ferrogels and magnetorheological elastomers allow a synergy of\nelasticity and magnetism. The interplay between elastic and magnetic properties\ngives rise to a unique reversible control of the material behavior by applying\nan external magnetic field. Albeit few works have been performed on the\ntime-dependent properties so far, understanding the dynamic behavior is the key\nto model many practical situations, e.g. applications as vibration absorbers.\nHere we present a way to calculate the frequency-dependent elastic moduli based\non the decomposition of the linear response to an external stress in normal\nmodes. We use a minimal three-dimensional dipole-spring model to theoretically\ndescribe the magnetic and elastic interactions on the mesoscopic level.\nSpecifically, the magnetic particles carry permanent magnetic dipole moments\nand are spatially arranged in a prescribed way, before they are linked by\nelastic springs. An external magnetic field aligns the magnetic moments. On the\none hand, we study regular lattice-like particle arrangements to compare with\nprevious results in the literature. On the other hand, we calculate the dynamic\nelastic moduli for irregular, more realistic particle distributions. Our\napproach measures the tunability of the linear dynamic response as a function\nof the particle arrangement, the system orientation with respect to the\nexternal magnetic field, as well as the magnitude of the magnetic interaction\nbetween the particles. The strength of the present approach is that it\nexplicitly connects the relaxational modes of the system with the rheological\nproperties as well as with the internal rearrangement of the particles in the\nsample, providing new insight into the dynamics of these remarkable materials."
    },
    {
        "anchor": "Eulerian and Lagrangian velocity statistics in weakly forced\n  two-dimensional turbulence: We present statistics of velocity fluctuations in both the Lagrangian and\nEulerian frame for weakly driven two-dimensional turbulence. We find that\nsimultaneous inverse energy and enstrophy ranges present in the Lagrangian and\nEulerian Fourier spectra are not directly echoed in real-space moments of\nvelocity difference. The spectral ranges, however, do line up very well with\nratios of the real-space moments {\\em local} exponents, indicating that though\nthe real-space moments are not scaling ``nicely'', the relative behavior of the\nvelocity difference probability distribution functions is changing over very\nshort ranges of length scales. Utilizing this technique we show that the ratios\nof the local exponents for Eulerian moments in weak two-dimensional turbulence\nbehave in agreement with Kolmogorov predictions over the spectrally identified\nranges. The Lagrangian local exponent ratios, however, behave in a different\nmanner compared to their Eulerian counterparts, and deviate significantly from\nwhat would be expected from Kolmogorov predictions.",
        "positive": "Investigation of $q$-dependent dynamical heterogeneity in a colloidal\n  gel by x-ray photon correlation spectroscopy: We use time-resolved X-Photon Correlation Spectroscopy to investigate the\nslow dynamics of colloidal gels made of moderately attractive carbon black\nparticles. We show that the slow dynamics is temporally heterogeneous and\nquantify its fluctuations by measuring the variance $\\chi$ of the instantaneous\nintensity correlation function. The amplitude of dynamical fluctuations has a\nnon-monotonic dependence on scattering vector $q$, in stark contrast with\nrecent experiments on strongly attractive colloidal gels [Duri and Cipelletti,\n\\textit{Europhys. Lett.} \\textbf{76}, 972 (2006)]. We propose a simple scaling\nargument for the $q$-dependence of fluctuations in glassy systems that\nrationalizes these findings."
    },
    {
        "anchor": "Quantum Step Heights in Hysteresis Loops of Molecular Magnets: We present an analytical theory on the heights of the quantum steps observed\nin the hysteresis loops of molecular magnets. By considering the dipolar\ninteraction between molecular spins, our theory successfully yields the step\nheights measured in experiments, and reveals a scaling law for the dependence\nof the heights on the sweeping rates hidden in the experiment data on Fe$_8$\nand Mn$_4$. With this theory, we show how to accurately determine the tunnel\nsplitting of a single molecular spin from the step heights.",
        "positive": "Finite bending and pattern evolution of the associated instability for a\n  dielectric elastomer slab: We investigate the finite bending and the associated bending instability of\nan incompressible dielectric slab subject to a combination of applied voltage\nand axial compression, using nonlinear electro-elasticity theory and its\nincremental version. We first study the static finite bending deformation of\nthe slab. We then derive the three-dimensional equations for the onset of\nsmall-amplitude wrinkles superimposed upon the finite bending. We use the\nsurface impedance matrix method to build a robust numerical procedure for\nsolving the resulting dispersion equations and determining the wrinkled shape\nof the slab at the onset of buckling. Our analysis is valid for dielectrics\nmodeled by a general free energy function. We then present illustrative\nnumerical calculations for ideal neo-Hookean dielectrics. In that case, we\nprovide an explicit treatment of the boundary value problem of the finite\nbending and derive closed-form expressions for the stresses and electric field\nin the body. For the incremental deformations, we validate our analysis by\nrecovering existing results in more specialized contexts. We show that the\napplied voltage has a destabilizing effect on the bending instability of the\nslab, while the effect of the axial load is more complex: when the voltage is\napplied, changing the axial loading will influence the true electric field in\nthe body, and induce competitive effects between the circumferential\ninstability due to the voltage and the axial instability due to the axial\ncompression. We even find circumstances where both instabilities cohabit to\ncreate two-dimensional patterns on the inner face of the bent sector."
    },
    {
        "anchor": "Solid-fluid transition in a granular shear flow: The rheology of a granular shear flow is studied in a quasi-2d rotating\ncylinder. Measurements are carried out near the midpoint along the length of\nthe surface flowing layer where the flow is steady and non-accelerating.\nStreakline photography and image analysis are used to obtain particle\nvelocities and positions. Different particle sizes and rotational speeds are\nconsidered. We find a sharp transition in the apparent viscosity ($\\eta$)\nvariation with rms velocity ($u$). In the fluid-like region above the depth\ncorresponding to the transition point (higher rms velocities) there is a rapid\nincrease in viscosity with decreasing rms velocity. Below the transition depth\nwe find $\\eta \\propto u^{-1.5}$ for all the different cases studied and the\nmaterial approaches an amorphous solid-like state deep in the layer. The\nvelocity distribution is Maxwellian above the transition point and a Poisson\nvelocity distribution is obtained deep in the layer. The observed transition\nappears to be analogous to a glass transition.",
        "positive": "Emergence and melting of active vortex crystals: Melting of two-dimensional (2D) equilibrium crystals, from superconducting\nvortex lattices to colloidal structures, is a complex phenomenon characterized\nby the sequential loss of positional and orientational order. Whereas melting\nprocesses in passive systems are typically triggered by external heat\ninjection, active matter crystals can self-assemble and melt into an active\nfluid by virtue of their intrinsic motility and inherent non-equilibrium\nstresses. Emergent crystal-like order has been observed in recent experiments\non suspensions of swimming sperm cells, fast-moving bacteria, Janus colloids,\nand in embryonic tissues. Yet, despite recent progress in the theoretical\ndescription of such systems, the non-equilibrium physics of active\ncrystallization and melting processes is not well understood. Here, we\nestablish the emergence and investigate the melting of self-organized vortex\ncrystals in 2D active fluids using an experimentally validated generalized\nToner-Tu theory. Performing hydrodynamic simulations at an unprecedented scale,\nwe identify two distinctly different melting scenarios: a hysteretic\ndiscontinuous phase transition and melting through an intermediary hexatic\nphase, both of which can be controlled by self-propulsion and active stresses.\nOur analysis further reveals intriguing transient features of active vortex\ncrystals including meta-stable superstructures of opposite spin polarity.\nGenerally, these results highlight the differences and similarities between\ncrystalline phases in active fluids and their equilibrium counterparts."
    },
    {
        "anchor": "Geometric visualization of self-propulsion in a complex medium: Combining geometric mechanics theory, laboratory robotic experiment and\nnumerical simulation, we study the locomotion in granular media (GM) of the\nsimplest non-inertial swimmer, the Purcell three-link swimmer. Using granular\nresistive force laws as inputs, the theory relates translation and rotation of\nthe body to shape changes (movements of the links). This allows analysis,\nvisualization, and prediction of effective movements that are verified by\nexperiment. The geometric approach also facilitates comparison between swimming\nin GM and in viscous fluids.",
        "positive": "Instability of toroidal nematics: Toroidal nematics are nematic liquid crystals confined within a circular\ntorus and subject to planar degenerate anchoring on the boundary of the torus.\nThey may be droplets floating in an isotropic environment or cavities carved\nout of a solid substrate. A universal solution of Frank's elastic free energy\nis an equilibrium configuration for the nematic director field, irrespective of\nthe values of the elastic constants, whose vector lines are the coaxial\nparallels of the torus. We explore the local stability of this configuration\nand identify a range of parameters where the main drive towards instability\ndoes not come from the surface-like elastic constant $K_{24}$ being large, but\nfrom the the ratio $K_2/K_3$ of the twist to bend elastic constants being\nsmall, which also makes our study relevant to chromonic liquid crystals."
    },
    {
        "anchor": "Templated self-assembly of gold nanoparticles in smectic liquid crystals\n  confined at 3D printed curved surfaces: The fabrication of assembled structures of topological defects in liquid\ncrystals (LCs) has attracted much attention during the last decade, stemming\nfrom the potential application of these defects in modern technologies. A range\nof techniques can be employed to create large areas of engineered defects in\nLCs, including mechanical shearing, chemical surface treatment, external\nfields, or geometric confinement. The technology of 3D printing has recently\nemerged as a powerful method to fabricate novel patterning topographies\ninaccessible by other microfabrication techniques, especially confining\ngeometries with curved topographies. In this work, we show the advantages of\nusing 3D-printed curved surfaces and controlled anchoring properties to confine\nLCs and engineer new structures of topological defects, whose structure we\nelucidate by comparison with a novel application of Landau-de Gennes free\nenergy minimization to the smectic A-nematic phase transition. We also\ndemonstrate the ability of these defects to act as a scaffold for assembling\ngold (Au) nanoparticles (NPs) into reconfigurable 3D structures. We discuss the\ncharacteristics of this templated self-assembly (TSA) approach and explain the\nrelationship between NP concentrations and defect structures with insights\ngained from numerical modeling. This work paves the way for a versatile\nplatform of LC defect-templated assembly of a range of functional nanomaterials\nuseful in the field of energy technology.",
        "positive": "Torque-induced reorientation in active fibre-reinforced materials: We introduce a continuum model for a fibre reinforced material in which the\nreference orientation of the fibre may evolve with time, under the influence of\nexternal stimuli. The model is formulated in the framework of large strain\nhyperelasticity and the kinematics of the continuum is described by both a\nposition vector and by a remodelling tensor which, in the present context, is\nan orthogonal tensor representing the fibre reorientation process. By imposing\nsuitable thermodynamical restrictions on the constitutive equation, we obtain\nan evolution equation of the remodelling tensor governed by the Eshelby torque,\nwhose stationary solutions are studied in absence of any external source terms.\nIt is shown that the fibres reorient themselves in a configuration that\nminimises the elastic energy and get aligned along a direction that may or may\nnot be of principal strain. The explicit analysis of the Hessian of the strain\nenergy density allows us to discriminate among the stationary solutions, which\nones are stable. Examples are given for passive reorientation processes driven\nby applied strains or external boundary tractions. % Applications of the\nproposed theory to biological tissues, nematic or magneto-electro active\nelastomers are foreseen."
    },
    {
        "anchor": "Small-scale demixing in confluent biological tissues: Surface tension governed by differential adhesion can drive fluid particle\nmixtures to sort into separate regions, i.e., demix. Does the same phenomenon\noccur in confluent biological tissues? We begin to answer this question for\nepithelial monolayers with a combination of theory via a vertex model and\nexperiments on keratinocyte monolayers. Vertex models are distinct from\nparticle models in that the interactions between the cells are shape-based, as\nopposed to distance-dependent. We investigate whether a disparity in cell shape\nor size alone is sufficient to drive demixing in bidisperse vertex model fluid\nmixtures. Surprisingly, we observe that both types of bidisperse systems\nrobustly mix on large lengthscales. On the other hand, shape disparity\ngenerates slight demixing over a few cell diameters, a phenomenon we term\nmicro-demixing. This result can be understood by examining the differential\nenergy barriers for neighbor exchanges (T1 transitions). Experiments with\nmixtures of wild-type and E-cadherin-deficient keratinocytes on a substrate are\nconsistent with the predicted phenomenon of micro-demixing, which biology may\nexploit to create subtle patterning. The robustness of mixing at large scales,\nhowever, suggests that despite some differences in cell shape and size,\nprogenitor cells can readily mix throughout a developing tissue until acquiring\nmeans of recognizing cells of different types.",
        "positive": "Flow and Arrest in Stressed Granular Materials: Flowing granular materials often abruptly arrest if not driven by sufficient\napplied stresses. Such abrupt cessation of motion can be economically expensive\nin industrial materials handling and processing, and is significantly\nconsequential in intermittent geophysical phenomena such as landslides and\nearthquakes. Using discrete element simulations, we calculate states of steady\nflow and arrest for granular materials under the conditions of constant applied\npressure and shear stress, which are also most relevant in practice. Here the\nmaterial can dilate or compact, and flow or arrest, in response to the applied\nstress. Our simulations highlight that under external stress, the intrinsic\nresponse of granular materials is characterized by uniquely-defined steady\nstates of flow or arrest, which are highly sensitive to interparticle friction.\nWhile the flowing states can be equivalently characterized by volume fraction,\ncoordination number or internal stress ratio, to characterize the states of\nshear arrest, one needs to also consider the structural anisotropy in the\ncontact network. We highlight the role of dilation in the flow-arrest\ntransition, and discuss our findings in the context of rheological transitions\nin granular materials."
    },
    {
        "anchor": "Breakdown of Energy Equipartition in a 2D Binary Vibrated Granular Gas: We report experiments on the equipartition of kinetic energy between grains\nmade of two different materials in a mixture of grains vibrated in 2\ndimensions. In general, the two types of grains do not attain the same granular\ntemperature, Tg = 1/2m v^2. However, the ratio of the two temperatures is\nconstant in the bulk of the system and independent of the vibration velocity.\nThe ratio depends strongly on the ratio of mass densities of the grains, but is\nnot sensitive to the inelasticity of grains. Also, this ratio is insensitive to\ncompositional variables of the mixture such as the number fraction of each\ncomponent and the total number density. We conclude that a single granular\ntemperature, as traditionally defined, does not characterize a multi-component\nmixture.",
        "positive": "Control of chemical reactions using electric field gradients: We examine theoretically a new idea for spatial and temporal control of\nchemical reactions. When chemical reactions take place in a mixture of\nsolvents, an external electric field can alter the local mixture composition\nthereby accelerating or decelerating the rate of reaction. The spatial\ndistribution of electric field strength can be non-trivial and depends on the\narrangement of the electrodes producing it. In the absence of electric field,\nthe mixture is homogeneous and the reaction takes place uniformly in the\nreactor volume. When an electric field is applied the solvents separate and\nreactants are concentrated in the same phase or separate to different phases,\ndepending on their relative miscibility in the solvents, and this can have a\nlarge effect on the kinetics of the reaction. This method could provide an\nalternative way to control runaway reactions and to increase the reaction rate\nwithout using catalysts."
    },
    {
        "anchor": "Pairing in asymmetric two-component fermion matter: We analyze the possibilities of pairing between two different fermion species\nin asymmetric matter at low density. While the direct interaction allows\npairing only for very small asymmetries, the pairing mediated by polarization\neffects is always possible, with a pronounced maximum at finite asymmetry. We\npresent analytical results up to second order in the low-density parameter $k_F\na$.",
        "positive": "Universal equation describes the shape of air bubbles trapped in ice: Water usually contains dissolved gases, and because freezing is a purifying\nprocess these gases must be expelled for ice to form. Bubbles appear at the\nfreezing front and are trapped into ice, making pores. These pores come in a\nrange of sizes from microns to millimeters and their shapes are peculiar; never\nspherical but elongated, and usually fore-aft asymmetric. We show that these\nremarkable shapes result of a delicate balance between freezing, capillarity\nand mass diffusion. A highly non-linear ordinary differential equation suffices\nto describe the bubbles, with only two non-dimensional parameters representing\nthe supersaturation and the freezing rate. Our experiments provide us with a\nlarge variety of pictures of bubble shapes. We show that all of them have their\nrounded tip well described by an asymptotic regime of the differential\nequation, and that most of them can have their full shape quantitatively\nmatched by a full solution. This enables the measurement of the freezing\nconditions of ice samples, and the design of freeze-cast porous materials.\nFurthermore, the equation exhibits a bifurcation that explains why some bubbles\ngrow indefinitely and make long cylindrical ``ice worms''."
    },
    {
        "anchor": "Adaptive locomotion of artificial microswimmers: Bacteria can exploit mechanics to display remarkable plasticity in response\nto locally changing physical and chemical conditions. Compliant structures play\na striking role in their taxis behavior, specifically for navigation inside\ncomplex and structured environments. Bioinspired mechanisms with rationally\ndesigned architectures capable of large, nonlinear deformation present\nopportunities for introducing autonomy into engineered small-scale devices.\nThis work analyzes the effect of hydrodynamic forces and rheology of local\nsurroundings on swimming at low Reynolds number, identifies the challenges and\nbenefits of utilizing elastohydrodynamic coupling in locomotion, and further\ndevelops a suite of machinery for building untethered microrobots with\nself-regulated mobility. We demonstrate that coupling the structural and\nmagnetic properties of artificial microswimmers with the dynamic properties of\nthe fluid leads to adaptive locomotion in the absence of on-board sensors.",
        "positive": "From Over-charging to Like-charge Attraction in the Weak Coupling Regime: Despite decades of intensive studies, the effective interactions between\nstrongly charged colloids still remain elusive. Here we show that a strongly\ncharged surface with a layer of condensed counter- ions behaves effectively as\na conductor, due to the mobile nature of the condensed ions. An external source\ncharge in its vicinity is therefore attracted towards the surface, due to the\nimage charge effect. This mechanism leads to correlational energies for\ncounter-ions condensed on two distinct surfaces, as well as for free ions in\nthe bulk. Generalizing Debye-Huckel theory and image charge methods, we\nanalytically calculate these correlation energies for the two-plates problem,\nat the iso-electric point, where condensed counterions precisely balance the\nbare surface charges. At this point, the effective interaction between two\nplates is always attractive at small separation and repulsive at large\nseparation."
    },
    {
        "anchor": "Pair correlation function of charge-stabilized colloidal systems under\n  sheared conditions: The pair correlation function of charge stabilized colloidal particles under\nstrongly sheared conditions is studied using the analytical intermediate\nasymptotics method recently developed in [L. Banetta and A. Zaccone, Phys. Rev.\nE 99, 052606 (2019)] to solve the steady-state Smoluchowski equation for medium\nto high values of the P\\'eclet number; the analytical theory works for dilute\nconditions. A rich physical behaviour is unveiled for the pair correlation\nfunction of colloids interacting via the repulsive Yukawa (or Debye-H\\\"uckel)\npotential, in both the extensional and compressional sectors of the solid\nangle. In the compression sector, a peak near contact is due to the advecting\naction of the flow and decreases upon increasing the coupling strength\nparameter $\\Gamma$ of the Yukawa potential. Upon increasing the screening\n(Debye) length $\\kappa^{-1}$, a secondary peak shows up, at a larger separation\ndistance, slightly less than the Debye length. While this secondary peak grows,\nthe primary peak near contact decreases. The secondary peak is attributed to\nthe competition between the advecting (attractive-like) action of the flow in\nthe compressions sector, and the repulsion due to the electrostatics. In the\nextensional sectors, a depletion layer (where the pair-correlation function is\nidentically zero) near contact is predicted, the width of which increases upon\nincreasing either $\\Gamma$ or $\\kappa^{-1}$.",
        "positive": "Equilibrium mappings in polar-isotropic confined active particles: Despite their fundamentally non-equilibrium nature, the individual and\ncollective behavior of active systems with polar propulsion and isotropic\ninteractions (polar-isotropic active systems) are remarkably well captured by\nequilibrium mapping techniques. Here we examine two signatures of equilibrium\nsystems -- the existence of a local free energy function and the independence\nof the coarse- grained behavior on the details of the microscopic dynamics --\nin polar-isotropic active particles confined by hard walls of arbitrary\ngeometry at the one-particle level. We find that boundaries that possess\nconcave regions make the density profile strongly dynamics-dependent and give\nit a nonlocal dependence on the geometry of the confining box. This in turn\nconstrains the scope of equilibrium mapping techniques in polar-isotropic\nactive systems."
    },
    {
        "anchor": "Self and Tracer Diffusion of Polymers in Solution: The literature on self- and tracer- diffusion of polymers in solution, and on\ntracer diffusion of probe polymers through solutions of matrix polymers, is\nreviewed. I show via systematic reanalysis that the entirety of the published\nliterature has its concentration c and matrix M and probe P molecular weight\ndependences described by a single functional form, namely the stretched\nexponential in c, P, and M. Correlations of the scaling prefactor and exponents\nwith polymer molecular weight, concentration, and size are examined. Scaling\nparameters for the diffusion of star polymers do not differ substantially from\nscaling parameters for the diffusion of linear chains of equal size.",
        "positive": "Dissipative particle dynamics simulation study on ATRP-brush\n  modification of variably shaped surfaces and biopolymer adsorption: We present a dissipative particle dynamics (DPD) simulation study on the\nsurface modification of initiator embedded microparticles (MPs) of different\nshapes via atom transfer radical polymerization (ATRP) brush growth. The\nsurface-initiated ATRP-brush growth leads to the formation of a more globular\nMP shape. We perform the comparative analysis of ATRP-brush growth on three\ndifferent forms of particle surfaces: cup surface, spherical surface, and flat\nsurface (rectangular/disk-shaped). First, we establish the chemical kinetics of\nthe brush growth: the monomer conversion and the reaction rates. We next argue\nthe structure changes (shape-modification) of brush-modified surfaces by\ncomputing the radial distribution function, spatial density distribution,\nradius of gyration, hydrodynamic radius, and shape factor. The polymer\nbrush-modified particles are well known as the carrier materials for enzyme\nimmobilization. Finally, we study the biopolymer adsorption on ATRP-brush\nmodified particles in a compatible solution. In particular, we explore the\neffect of ATRP-brush length, biopolymer chain length, and concentration on the\nadsorption process. Our results illustrate the enhanced biopolymer adsorption\nwith increased brush length, initiator concentration, and biopolymer\nconcentration. Most importantly, the flat surface loads more biopolymers than\nthe other two surfaces when adsorption reaches saturation. The experimental\nresults verified the same, considering the disk-shaped flat surface particle,\ncup, and spherical particles."
    },
    {
        "anchor": "Facilitated polymer capture by charge inverted electroosmotic flow in\n  voltage-driven polymer translocation: The optimal functioning of nanopore-based biosensing tools necessitates rapid\npolymer capture from the ion reservoir. We identify an ionic\ncorrelation-induced transport mechanism that provides this condition without\nthe chemical modification of the polymer or the pore surface. In the typical\nexperimental configuration where a negatively charged silicon-based pore\nconfines a 1:1 electrolyte solution, anionic polymer capture is limited by\nelectrostatic polymer-membrane repulsion and the electroosmotic (EO) flow.\nAdded multivalent cations suppress the electrostatic barrier and revers the\npore charge, inverting the direction of the EO flow that drags the polymer to\nthe trans side. This inverted EO flow can be used to speed up polymer capture\nfrom the reservoir and to transport weakly or non-uniformly charged polymers\nthat cannot be controlled by electrophoresis.",
        "positive": "Large scale three dimensional simulations of hybrid block\n  copolymer/nanoparticle systems: Block copolymer melts self-assemble in the bulk into a variety of\nnanostructures, making them perfect candidates to template the position of\nnanoparticles. The morphological changes of block copolymers are studied in the\npresence of a considerable filling fraction of colloids. Furthermore, colloids\ncan be found to assemble into ordered hexagonally close-packed structures in a\ndefined number of layers when softly confined within the phase-separated block\ncopolymer. A high concentration of interface-compatible nanoparticles leads to\ncomplex block copolymer morphologies depending on the polymeric composition.\nMacrophase separation between the colloids and the block copolymer can be\ninduced if colloids are unsolvable within the matrix. This leads to the\nformation of ellipsoid-shaped polymer-rich domains elongated along the\ndirection perpendicular to the interface between block copolymer domains."
    },
    {
        "anchor": "Thermally Activated Asymmetric Structural Recovery in a Soft Glassy\n  Nano-Clay Suspension: In this work we study structural recovery of a soft glassy Laponite\nsuspension by monitoring temporal evolution of elastic modulus under isothermal\nconditions as well as following step temperature jumps. Interestingly,\nevolution behavior under isothermal conditions indicates the rate, and not the\npath of structural recovery, to be dependent on temperature. The experiments\ncarried out under temperature jump conditions however trace a different path of\nstructural recovery, which shows strong dependence on temperature and the\ndirection of change. Further investigation of the system suggests that this\nbehavior can be attributed to restricted mobility of counterions associated\nwith Laponite particle at the time of temperature change, which do not allow\ncounterion concentration to reach equilibrium value associated with the changed\ntemperature. Interestingly this effect is observed to be comparable with other\nglassy molecular and soft materials, which while evolve in a self-similar\nfashion under isothermal conditions, show asymmetric behavior upon temperature\nchange.",
        "positive": "Dynamics of a Bose-Einstein condensate in optical trap: The dynamics of a 2D Bose-Einstein condensate in optical trap is studied\ntaking into consideration fluctuations of the far-off-resonance laser field\nintensity. The problem is described in the frame of the mean field\nGross-Pitaevskii equation with randomly varying trap potential. An analytic\napproach based on the moments method has been employed to describe the noise\ninduced evolution of the condensate properties. Stochastic parametric resonance\nin oscillations of the condensate width is proved to exist. For the condensate\nwith negative scattering length of atoms, it is shown that the noise can delay\nor even arrest the collapse. Analytical predictions are confirmed by numerical\nsimulations of the underlying PDE and ODE models."
    },
    {
        "anchor": "Electrostatic Interactions between Janus Particles: In this paper we study the electrostatic properties of `Janus' spheres with\nunequal charge densities on both hemispheres. We introduce a method to compare\nprimitive-model Monte Carlo simulations of the ionic double layer with\npredictions of (mean-field) nonlinear Poisson-Boltzmann theory. We also derive\npractical DLVO-like expressions that describe the Janus-particle pair\ninteractions by mean-field theory. Using a large set of parameters, we are able\nto probe the range of validity of the Poisson-Boltzmann approximation, and thus\nof DLVO-like theories, for such particles. For homogeneously charged spheres\nthis range corresponds well to the range that was predicted by\nfield-theoretical studies of homogeneously charged flat surfaces. Moreover, we\nfind similar ranges for colloids with a Janus-type charge distribution. The\ntechniques and parameters we introduce show promise for future studies of an\neven wider class of charged-patterned particles.",
        "positive": "High-throughput and long-term observation of compartmentalized\n  biochemical oscillators: We report the splitting of an oscillating DNA circuit into $\\sim 700$\ndroplets with picoliter volumes. Upon incubation at constant temperature, the\ndroplets display sustained oscillations that can be observed for more than a\nday. Superimposed to the bulk behaviour, we find two intriguing new phenomena -\nslow desynchronization between the compartments and kinematic spatial waves -\nand investigate their possible origin. This approach provides a route to study\nthe influence of small volume effects in biology, and paves the way to\ntechnological applications of compartmentalized molecular programs controlling\ncomplex dynamics."
    },
    {
        "anchor": "Passive Janus Particles Are Self-propelled in Active Nematics: While active systems possess notable potential to form the foundation of new\nclasses of autonomous materials, designing systems that can extract functional\nwork from active surroundings has proven challenging. In this work, we extend\nthese efforts to the realm of designed active liquid crystal/colloidal\ncomposites. We propose suspending colloidal particles with Janus anchoring\nconditions in an active nematic medium. These passive Janus particles become\neffectively self-propelled once immersed into an active nematic bath. The\nself-propulsion of passive Janus particles arises from the effective $+1/2$\ntopological charge their surface enforces on the surrounding active fluid. We\nanalytically study their dynamics and the orientational dependence on the\nposition of a companion $-1/2$ defect. We predict that at sufficiently small\nactivity, the colloid and companion defect remain bound to each other, with the\ndefect strongly orienting the colloid to propel either parallel or\nperpendicular to the nematic. At sufficiently high activity, we predict an\nunbinding of the colloid/defect pair. This work demonstrates how suspending\nengineered colloids in active liquid crystals may present a path to extracting\nactivity to drive functionality.",
        "positive": "Thermal properties of athermal granular materials: Dry granular materials consist of a vast ensemble of discrete solid\nparticles, interacting through complex frictional forces at the contact points.\nThe particles are so large that these systems are believed to be completely\nathermal. Here, we arrest the dynamics of a flowing granular material in a\nsteady-state flow configuration, enabling an isolated examination of aging at\nthe particle contacts without granular rearrangements. Our findings reveal that\nthe evolution of interparticle forces within the arrested athermal granular\nnetwork results in the spontaneous increase of the system's yield stress. This\nstrengthening process is logarithmic in time with a rate that depends on\ntemperature. We demonstrate that the material's stress relaxation exhibits\nsimilar time- and temperature-dependent behavior, suggesting a shared origin\nfor aging and stress relaxation in these systems governed by thermal molecular\nprocesses at the scale of the grain contacts."
    },
    {
        "anchor": "Measurement of the hydrodynamic forces between two polymer-coated\n  spheres: The hydrodynamic forces between Brownian spheres are determined from a\nmeasurement of the correlated thermal fluctuations in particle position using a\nnew method, two-particle cross-correlation spectroscopy (TCS). A pair of 1.3 um\ndiameter polymer-coated poly(methyl methacrylate) were held at separations of\nbetween 2 um and 20 um using optical traps. The mobility tensor is determined\ndirectly from the statistically-averaged Brownian fluctuations of the two\nspheres. The observed distance dependence of the mobility tensor is in\nquantitative agreement with low-Reynolds number calculations.",
        "positive": "Charge regulation: a generalized boundary condition?: The three most commonly-used boundary conditions for charged colloidal\nsystems are constant charge (insulator), constant potential (conducting\nelectrode) and charge regulation (ionizable groups at the surface). It is\nusually believed that the charge regulation is a generalized boundary condition\nthat reduces in some specific limits to either constant charge or constant\npotential boundary conditions. By computing the disjoining pressure between two\nsymmetric planes for these three boundary conditions, both numerically (for all\ninter-plate separations) and analytically (for small inter-plate separations),\nwe show that this is not, in general, the case. In fact, the limit of charge\nregulation is a separate boundary condition, yielding a disjoining pressure\nwith a different characteristic separation-scaling. Our findings are supported\nby several examples demonstrating that the disjoining pressure at small\nseparations for the charge regulation boundary-condition depends on the details\nof the dissociation/association process."
    },
    {
        "anchor": "Orientational ordering in crumpled elastic sheets: We report an experimental study of the development of orientational order in\na crumpled sheet, with a particular focus on the role played by the geometry of\nconfinement. Our experiments are performed on elastomeric sheets immersed in a\nfluid, so that the effects of plasticity and friction are suppressed. When the\nsheet is crumpled either axially or radially within a cylinder, we find that\nthe sheet aligns with the flat or the curved wall, depending on the aspect\nratio of the cylinder. Nematic correlations develop between the normals of the\nsheets at relatively low volume fractions and the crumpled object has large\ndensity fluctuations corresponding to the stacking of parallel sheets. The\naligning effect of the wall breaks symmetry and selects the direction of\nordering.",
        "positive": "Impact of wettability correlations on multiphase flow through porous\n  media: In the last decades, significant progress has been made in understanding the\nmultiphase displacement through porous media with homogeneous wettability and\nits relation to the pore geometry. However, the role of wettability at the\nscale of the pore remains still little understood. In the present study the\ndisplacement of immiscible fluids through a two-dimensional porous medium is\nsimulated by means of a mesoscopic particle approach. The substrate is\ndescribed as an assembly of non-overlapping circular disks whose preferential\nwettability is distributed according to prescribed spatial correlations, from\npore scale up to domains at system size. We analyze how this well-defined\nheterogeneous wettability affects the flow and try to establish a relationship\namong wettability-correlations and large-scale properties of the multiphase\nflow."
    },
    {
        "anchor": "Theory of interacting dislocations on cylinders: We study the mechanics and statistical physics of dislocations interacting on\ncylinders, motivated by the elongation of rod-shaped bacterial cell walls and\ncylindrical assemblies of colloidal particles subject to external stresses. The\ninteraction energy and forces between dislocations are solved analytically, and\nanalyzed asymptotically. The results of continuum elastic theory agree well\nwith numerical simulations on finite lattices even for relatively small\nsystems. Isolated dislocations on a cylinder act like grain boundaries. With\ncolloidal crystals in mind, we show that saddle points are created by a\nPeach-Koehler force on the dislocations in the circumferential direction,\ncausing dislocation pairs to unbind. The thermal nucleation rate of dislocation\nunbinding is calculated, for an arbitrary mobility tensor and external stress,\nincluding the case of a twist-induced Peach-Koehler force along the cylinder\naxis. Surprisingly rich phenomena arise for dislocations on cylinders, despite\ntheir vanishing Gaussian curvature.",
        "positive": "Casimir force in dense confined electrolytes: Understanding the force between charged surfaces immersed in an electrolyte\nsolution is a classic problem in soft matter and liquid-state theory. Recent\nexperiments showed that the force decays exponentially but the characteristic\ndecay length in a concentrated electrolyte is significantly larger than what\nliquid-state theories predict based on analysing correlation functions in the\nbulk electrolyte. Inspired by the classical Casimir effect, we consider an\nalternative mechanism for force generation, namely the confinement of density\nfluctuations in the electrolyte by the walls. We show analytically within the\nrandom phase approximation, which assumes the ions to be point charges, that\nthis fluctuation-induced force is attractive and also decays exponentially,\nalbeit with a decay length that is half of the bulk correlation length. These\npredictions change dramatically when excluded volume effects are accounted for\nwithin the mean spherical approximation. At high ion concentrations the Casimir\nforce is found to be exponentially damped oscillatory as a function of the\ndistance between the confining surfaces. Our analysis does not resolve the\nriddle of the anomalously long screening length observed in experiments, but\nsuggests that the Casimir force due to mode restriction in density fluctuations\ncould be an hitherto under-appreciated source of surface-surface interaction."
    },
    {
        "anchor": "Optimal Control Strategies for Active Particle Navigation: The quest for the optimal navigation strategy in a complex environment is at\nthe heart of microswimmer applications like cargo carriage or drug targeting to\ncancer cells. Here, we formulate a variational Fermat's principle for\nmicroswimmers determining the optimal path regarding travelling time, energy\ndissipation or fuel consumption. For piecewise constant forces (or flow\nfields), the principle leads to Snell's law, showing that the optimal path is\npiecewise linear, as for light rays, but with a generalized refraction law. For\ncomplex environments, like general 1D-, shear- or vortex-fields, we obtain\nexact analytical expressions for the optimal path, showing, for example, that\nmicroswimmers sometimes have to temporarily navigate away from their target to\nreach it fastest. Our results might be useful to benchmark algorithmic schemes\nfor optimal navigation.",
        "positive": "Novel method for determination of contact angle of highly volatile\n  liquids: In this paper, a novel method for the measurement of equilibrium contact\nangle of highly volatile binary liquids is proposed. The proposed method, which\ncombines finite element method and energy equilibration, is able to calculate\nthe solid-liquid contact area. The calculated solid-liquid contact area can\nthen be used to estimate the equilibrium contact angle. Using the proposed\napproach, the contact angles of binary liquid droplet on a microgrooved and\nsmooth polycarbonate substrate were calculated. The proposed method can be an\nefficient tool for finding the contact angle of all liquids (both volatile and\nnon-volatile)."
    },
    {
        "anchor": "Interpenetration as a Mechanism for Liquid-Liquid Phase Transitions: We study simple lattice systems to demonstrate the influence of\ninterpenetrating bond networks on phase behavior. We promote interpenetration\nby using a Hamiltonian with a weakly repulsive interaction with nearest\nneighbors and an attractive interaction with second-nearest neighbors. In this\nway, bond networks will form between second-nearest neighbors, allowing for two\n(locally) distinct networks to form. We obtain the phase behavior from analytic\nsolution in the mean-field approximation and exact solution on the Bethe\nlattice. We compare these results with exact numerical results for the phase\nbehavior from grand canonical Monte Carlo simulations on square, cubic, and\ntetrahedral lattices. All results show that these simple systems exhibit rich\nphase diagrams with two fluid-fluid critical points and three thermodynamically\ndistinct phases. We also consider including third-nearest-neighbor\ninteractions, which give rise to a phase diagram with four critical points and\nfive thermodynamically distinct phases. Thus the interpenetration mechanism\nprovides a simple route to generate multiple liquid phases in single-component\nsystems, such as hypothesized in water and observed in several model and\nexperimental systems. Additionally, interpenetration of many such networks\nappears plausible in a recently considered material made from nanoparticles\nfunctionalized by single strands of DNA.",
        "positive": "Large-scale collective properties of self-propelled rods: We study, in two space dimensions, the large-scale properties of collections\nof constant-speed polar point particles interacting locally by nematic\nalignment in the presence of noise. This minimal approach to self-propelled\nrods allows one to deal with large numbers of particles, revealing a\nphenomenology previously unseen in more complicated models, and moreover\ndistinctively different from both that of the purely polar case (e.g. the\nVicsek model) and of active nematics."
    },
    {
        "anchor": "Slow plasmon modes in polymeric salt solutions: The dynamics of polymeric salt solutions are presented. The salt consists of\nchains $\\rm A$ and $\\rm B$, which are chemically different and interact with a\nFlory-interaction parameter $\\chi$, the $\\rm A$ chain ends carry a positive\ncharge whereas the $\\rm B$ chain ends are modified by negative charges. The\nstatic structure factor shows a peak corresponding to a micro phase separation.\nAt low momentum transfer, the interdiffusion mode is driven by electrostatics\nand is of the plasmon-type, but with an unusually low frequency, easily\naccessible by experiments. This is due to the polymer connectivity that\nintroduces high friction and amplifies the charge scattering thus allowing for\nlow charge densities. The interdiffusion mode shows a minimum (critical slowing\ndown) at finite $k$ when the interaction parameter increases we find then a low\n$k$ frequency quasi-plateau.",
        "positive": "Soft-Pinning: Experimental Validation of Static Correlations in\n  Supercooled Molecular Glass-forming Liquids: Enormous enhancement in the viscosity of a liquid near its glass transition\nis generally connected to the growing many-body static correlations near the\ntransition, often coined as `amorphous ordering'. Estimating the length scales\nof such correlations in different glass-forming liquids is highly important to\nunravel the physics of glass formation. Experiments on molecular glass-forming\nliquids become pivotal in this scenario as the viscosity grows several folds\n($\\sim 10^{14}$), simulations or colloidal glass experiments fail to access the\nlong-time scales required. Here we design an experiment to extract the static\nlength scales in molecular liquids using dilute amounts of another large\nmolecule as a pinning site. Results from dielectric relaxation experiments on\nsupercooled glycerol with different pinning concentrations of sorbitol and the\nsimulations on a few model glass-forming liquids with pinning sites indicate\nthe robustness of the proposed method, opening a plethora of opportunity to\nstudy the physics of other glass-forming liquids."
    },
    {
        "anchor": "Modeling of Intermediate Structures and Chain Conformation in\n  Silica-Latex Nanocomposites Observed by SANS During Annealing: The evolution of the polymer structure during nanocomposite formation and\nannealing of silica-latex nanocomposites is studied using contrast-variation\nsmall angle neutron scattering. The experimental system is made of silica\nnanoparticles (Rsi \\approx 8 nm) and a mixture of purpose-synthesized\nhydrogenated and deuterated nanolatex (Rlatex \\approx 12.5 nm). The progressive\ndisappearance of the latex beads by chain interdiffusion and release in the\nnanocomposites is analyzed quantitatively with a model for the scattered\nintensity of hairy latex beads and an RPA description of the free chains. In\nsilica-free matrices and nanocomposites of low silica content (7%v), the\nannealing procedure over weeks at up to Tg + 85 K results in a molecular\ndispersion of chains, the radius of gyration of which is reported. At higher\nsilica content (20%v), chain interdiffusion seems to be slowed down on\ntime-scales of weeks, reaching a molecular dispersion only at the strongest\nannealing. Chain radii of gyration are found to be unaffected by the presence\nof the silica filler.",
        "positive": "Unusual swelling of a polymer in a bacterial bath: The equilibrium structure and dynamics of a single polymer chain in a thermal\nsolvent is by now well-understood in terms of scaling laws. Here we consider a\npolymer in a bacterial bath, i.e. in a solvent consisting of active particles\nwhich bring in nonequilibrium fluctuations. Using computer simulations of a\nself-avoiding polymer chain in two dimensions which is exposed to a dilute bath\nof active particles, we show that the Flory-scaling exponent is unaffected by\nthe bath activity provided the chain is very long. Conversely, for shorter\nchains, there is a nontrivial coupling between the bacteria intruding into the\nchain which may stiffen and expand the chain in a nonuniversal way. As a\nfunction of the molecular weight, the swelling first scales faster than\ndescribed by the Flory exponent, then an unusual plateau-like behaviour is\nreached and finally a crossover to the universal Flory behaviour is observed.\nAs a function of bacterial activity, the chain end-to-end distance exhibits a\npronounced non-monotonicity. Moreover, the mean-square displacement of the\ncenter of mass of the chain shows a ballistic behaviour at intermediate times\nas induced by the active solvent. Our predictions are verifiable in\ntwo-dimensional bacterial suspensions and for colloidal model chains exposed to\nartificial colloidal microswimmers."
    },
    {
        "anchor": "Granular Packings: Nonlinear elasticity, sound propagation and\n  collective relaxation dynamics: Experiments on isotropic compression of a granular assembly of spheres show\nthat the shear and bulk moduli vary with the confining pressure faster than the\n1/3 power law predicted by Hertz-Mindlin effective medium theories (EMT) of\ncontact elasticity. Moreover, the ratio between the moduli is found to be\nlarger than the prediction of the elastic theory by a constant value. The\nunderstanding of these discrepancies has been a longstanding question in the\nfield of granular matter. Here we perform a test of the applicability of\nelasticity theory to granular materials. We perform sound propagation\nexperiments, numerical simulations and theoretical studies to understand the\nelastic response of a deforming granular assembly of soft spheres under\nisotropic loading. Our results for the behavior of the elastic moduli of the\nsystem agree very well with experiments. We show that the elasticity partially\ndescribes the experimental and numerical results for a system under\ncompressional loads. However, it drastically fails for systems under shear\nperturbations, particularly for packings without tangential forces and\nfriction. Our work indicates that a correct treatment should include not only\nthe purely elastic response but also collective relaxation mechanisms related\nto structural disorder and nonaffine motion of grains.",
        "positive": "Chromatic patchy particles: effects of specific interactions on liquid\n  structure: We study the structural and thermodynamic properties of patchy particle\nliquids, with a special focus on the role of \"color\", i.e. specific\ninteractions between individual patches. A possible experimental realization of\nsuch \"chromatic\" interactions is by decorating the particle patches with\nsingle-stranded DNA linkers. The complementarity of the linkers can promote\nselective bond formation between predetermined pairs of patches. By using MD\nsimulations, we compare the local connectivity, the bond orientation order, and\nother structural properties of the aggregates formed by the \"colored\" and\n\"colorless\" systems. The analysis is done for spherical particles with two\ndifferent patch arrangements (tetrahedral and cubic). It is found that the\naggregated (liquid) phase of the \"colorless\" patchy particles is better\nconnected, denser and typically has stronger local order than the corresponding\n\"colored\" one. This, in turn, makes the colored liquid less stable\nthermodynamically. Specifically, we predict that in a typical case the\nchromatic interactions should increase the relative stability of the\ncrystalline phase with respect to the disordered liquid, thus expanding its\nregion in the phase diagram."
    },
    {
        "anchor": "The Perfectly Matched Layer for nonlinear and matter waves: We discuss how the Perfectly Matched Layer (PML) can be adapted to numerical\nsimulations of nonlinear and matter wave systems, such as Bose-Einstein\ncondensates. We also present some examples which illustrate the benefits of\nusing the PML in the simulation of nonlinear and matter waves.",
        "positive": "Spin-charge separation in ultra-cold quantum gases: We investigate the physical properties of quasi-1D quantum gases of fermion\natoms confined in harmonic traps. Using the fact that for a homogeneous gas,\nthe low energy properties are exactly described by a Luttinger model, we\nanalyze the nature and manifestations of the spin-charge separation. Finally we\ndiscuss the necessary physical conditions and experimental limitations\nconfronting possible experimental implementations."
    },
    {
        "anchor": "Understanding the rheology of kaolinite clay suspensions using Bayesian\n  inference: Mud is a suspension of fine-grained particles (sand, silt, and clay) in\nwater. The interaction of clay minerals in mud gives rise to complex\nrheological behaviors, such as yield stress, thixotropy and viscoelasticity.\nHere, we experimentally examine the flow behaviors of kaolinite clay\nsuspensions, a model mud, using steady shear rheometry. The flow curves exhibit\nboth yield stress and rheological hysteresis behaviors for various kaolinite\nvolume fractions ($\\phi_k$). Further understanding of these behaviors requires\nfitting to existing constitutive models, which is challenging due to numerous\nfitting parameters. To this end, we employ a Bayesian inference method, Markov\nchain Monte Carlo (MCMC), to fit the experimental flow curves to a\nmicrostructural viscoelastic model. The method allows us to estimate the\nrheological properties of the clay suspensions, such as viscosity, yield\nstress, and relaxation time scales. The comparison of the inherent relaxation\ntime scales suggests that kaolinite clay suspensions are strongly viscoelastic\nand weakly thixotropic at relatively low $\\phi_k$, while being almost inelastic\nand purely thixotropic at high $\\phi_k$. Overall, our results provide a\nframework for predictive model fitting to elucidate the rheological behaviors\nof natural materials and other structured fluids.",
        "positive": "Bjerrum pairing correlations at charged interfaces: Electrostatic correlations play a fundamental role in aqueous solutions. In\nthis letter, we identify transverse and lateral correlations as two mutually\nexclusive regimes. We show that the transverse regime leads to binding by\ngeneralization of Bjerrum pair formation theory, yielding binding constants\nfrom first-principle statistical-mechanical calculations. We compare our\ntheoretical predictions with experiments on charged membranes and Langmuir\nmonolayers and find good agreement. We contrast our approach with existing\ntheories in the strong-coupling limit and on charged modulated interfaces, and\ndiscuss different scenarios that lead to charge reversal and equal-sign\nattraction by macro-ions."
    },
    {
        "anchor": "On the thermal properties of knotted block copolymer rings: The thermal properties of coarse grained knotted polymers containing two\nkinds of monomers $A$ and $B$ fluctuating in a solution are investigated on a\nsimple cubic lattice using the Wang-Landau MC algorithm. These knots have a\nmore complex phase diagram than knots formed by homopolymers, including the\npossible presence of metastable states. Two different setups are considered: i)\ncharged block copolymers in a ion solution and ii) neutral copolymers with the\n$A$ monomers above and the $B$ monomers below the theta point. A precise\ninterpretation of the peaks observed in the plots of the specific heat capacity\nis provided. In view of possible applications in medicine and the construction\nof intelligent materials, it is also shown that the behavior of copolymer rings\ncan be tuned by changing both their monomer configuration and topology. We find\nthat the most stable compact states are formed by charged copolymers in which\nvery short segments with $A$ monomers are alternated by short segments with $B$\nmonomers. In such knots the transition from the compact to the expanded state\nis very fast, leading to a narrow and high peak in the specific heat capacity\nwhich appears at very high temperatures. The effects of topology allow to tune\nthe radius of gyration of the knotted polymer ring and to increase or decrease\nthe temperatures at which the observed phase transitions or rearrangements of\nthe system occur. While we observe a general fading out of the influence of\ntopology in longer polymers, our simulations have captured a few exceptions to\nthis rule.",
        "positive": "Theory for polymer coils with necklaces of micelles: If many micelles adsorb onto the same polymer molecule then they are said to\nform a necklace. A minimal model of such a necklace is proposed and shown to be\nalmost equivalent to a 1-dimensional fluid with nearest-neighbour interactions.\nThe thermodynamic functions of this fluid are obtained and then used to predict\nthe change in the critical micellar concentration of the surfactant in the\npresence of the polymer. If the amount of polymer is not too large there are\ntwo critical micellar concentrations, one for micelles in necklaces and one for\nfree micelles."
    },
    {
        "anchor": "Simulations of collision times in gravity driven granular flow: We use simulations to investigate collision time distributions as one\napproaches the static limit of steady-state flow of dry granular matter. The\ncollision times fall in a power-law distribution with an exponent dictated by\nwhether the grains are ordered or disordered. Remarkably, the exponents have\nalmost no dependence on dimension. We are also able to resolve a disagreement\nbetween simulation and experiments on the exponent of the collision time\npower-law distribution.",
        "positive": "Physical aspects of heterogeneities in multi-component lipid membranes: Ever since the raft model for biomembranes has been proposed, the traditional\nview of biomembranes based on the fluid-mosaic model has been altered. In the\nraft model, dynamical heterogeneities in multi-component lipid bilayers play an\nessential role. Focusing on the lateral phase separation of biomembranes and\nvesicles, we review some of the most relevant research conducted over the last\ndecade. We mainly refer to those experimental works that are based on physical\nchemistry approach, and to theoretical explanations given in terms of soft\nmatter physics. In the first part, we describe the phase behavior and the\nconformation of multi-component lipid bilayers. After formulating the\nhydrodynamics of fluid membranes in presence of the surrounding solvent, we\ndiscuss the domain growth-law and decay rate of concentration fluctuations.\nFinally, we review several attempts to describe membrane rafts as\ntwo-dimensional microemulsion."
    },
    {
        "anchor": "The role of water and steric constraints in the kinetics of\n  cavity-ligand unbinding: A key factor influencing a drug's efficacy is its residence time in the\nbinding pocket of the host protein. Using atomistic computer simulation to\npredict this residence time and the associated dissociation process is a\ndesirable but extremely difficult task due to the long timescales involved.\nThis gets further complicated by the presence of biophysical factors such as\nsteric and solvation effects. In this work, we perform molecular dynamics (MD)\nsimulations of the unbinding of a popular prototypical hydrophobic\ncavity-ligand system using a metadynamics based approach that allows direct\nassessment of kinetic pathways and parameters. When constrained to move in an\naxial manner, we find the unbinding time to be on the order of 4000 sec. In\naccordance with previous studies, we find that the ligand must pass through a\nregion of sharp dewetting transition manifested by sudden and high fluctuations\nin solvent density in the cavity. When we remove the steric constraints on\nligand, the unbinding happens predominantly by an alternate pathway, where the\nunbinding becomes 20 times faster, and the sharp dewetting transition instead\nbecomes continuous. We validate the unbinding timescales from metadynamics\nthrough a Poisson analysis, and by comparison through detailed balance to\nbinding timescale estimates from unbiased MD. This work demonstrates that\nenhanced sampling can be used to perform explicit solvent molecular dynamics\nstudies at timescales previously unattainable, obtaining direct and reliable\npictures of the underlying physio-chemical factors including free energies and\nrate constants.",
        "positive": "Simple and Robust Solver for the Poisson-Boltzmann Equation: A variational approach is used to develop a robust numerical procedure for\nsolving the nonlinear Poisson-Boltzmann equation. Following Maggs et al., we\nconstruct an appropriate constrained free energy functional, such that its\nEuler-Lagrange equations are equivalent to the Poisson-Boltzmann equation. We\nthen develop, implement, and test an algorithm for its numerical minimization,\nwhich is quite simple and unconditionally stable. The analytic solution for\nplanar geometry is used for validation. Furthermore, some results are presented\nfor a charged colloidal sphere surrounded by counterions."
    },
    {
        "anchor": "Continuum simulations of shocks and patterns in vertically oscillated\n  granular layers: We study interactions between shocks and standing-wave patterns in vertically\noscillated layers of granular media using three-dimensional, time-dependent\nnumerical solutions of continuum equations to Navier-Stokes order. We simulate\na layer of grains atop a plate that oscillates sinusoidally in the direction of\ngravity. Standing waves form stripe patterns when the accelerational amplitude\nof the plate's oscillation exceeds a critical value. Shocks also form with each\ncollision between the layer and the plate; we show that pressure gradients\nformed by these shocks cause the flow to reverse direction within the layer.\nThis reversal leads to an oscillatory state of the pattern that is subharmonic\nwith respect to the plate's oscillation. Finally, we study the relationship\nbetween shocks and patterns in layers oscillated at various frequencies and\nshow that the pattern wavelength increases monotonically as the shock strength\nincreases.",
        "positive": "Quantum Field Theory of Forward Rates with Stochastic Volatility: In a recent formulation of a quantum field theory of forward rates, the\nvolatility of the forward rates was taken to be deterministic. The field theory\nof the forward rates is generalized to the case of stochastic volatility. Two\ncases are analyzed, firstly when volatility is taken to be a function of the\nforward rates, and secondly when volatility is taken to be an independent\nquantum field. Since volatiltiy is a positive valued quantum field, the full\ntheory turns out to be an interacting nonlinear quantum field theory in two\ndimensions. The state space and Hamiltonian for the interacting theory are\nobtained, and shown to have a nontrivial structure due to the manifold moving\nwith a constant velocity. The no arbitrage condition is reformulated in terms\nof the Hamiltonian of the system, and then exactly solved for the nonlinear\ninteracting case."
    },
    {
        "anchor": "Age-dependent transient shear banding in soft glasses: We study numerically the formation of long-lived transient shear bands during\nshear startup within two models of soft glasses (a simple fluidity model and an\nadapted `soft glassy rheology' model). The degree and duration of banding\ndepends strongly on the applied shear rate, and on sample age before shearing.\nIn both models the ultimate steady flow state is homogeneous at all shear\nrates, consistent with the underlying constitutive curve being monotonic.\nHowever, particularly in the SGR case, the transient bands can be extremely\nlong lived. The banding instability is neither `purely viscous' nor `purely\nelastic' in origin, but is closely associated with stress overshoot in startup\nflow.",
        "positive": "Lagrangian statistics and coherent structures in two-dimensional\n  turbulence: Measurements of Lagrangian single-point and multiple-point statistics in a\nquasi-two-dimensional stratifed layer system are reported. The system consists\nof a layer of salt water over an immiscible layer of Fluorinert and is forced\nelectromagnetically so that mean-squared vorticity is injected at a\nwell-defined spatial scale. Simultaneous cascades develop in which enstrophy\nflows predominately to small scales whereas energy cascades, on average, to\nlarger scales. Lagrangian velocity correlations and one- and two-point\ndisplacements are measured for random initial conditions and for initial\npositions within topological centers and saddles. The behavior of these\nquantities can be understood in terms of the trapping characteristics of\nlong-lived centers, the slow motion near strong saddles, and the rapid\nfluctuations outside of either centers or saddles."
    },
    {
        "anchor": "Bose-Einstein Condensation in a simple Microtrap: A Bose-Einstein condensate is created in a simple and robust miniature\nIoffe-Pritchard trap, the so-called Z trap. This trap follows from the mere\ncombination of a Z-shaped current carrying wire and a homogeneous bias field.\nThe experimental procedure allows condensation of typically 3x10^5 Rb-87 atoms\nin the |F=2, m_F=2> state close to any mirroring surface, irrespective of its\nstructure, thus it is ideally suited as a source for cold atom physics near\nsurfaces.",
        "positive": "Transitions of tethered chain molecules under tension: An applied tension force changes the equilibrium conformations of a polymer\nchain tethered to a planar substrate and thus affects the adsorption transition\nas well as the coil-globule and crystallization transitions. Conversely,\nsolvent quality and surface attraction are reflected in equilibrium\nforce-extension curves that can be measured in experiments. To investigate\nthese effects theoretically, we study tethered chains under tension with\nWang-Landau simulations of a bond-fluctuation lattice model. Applying our model\nto pulling experiments on biological molecules we obtain a good description of\nexperimental data in the intermediate force range, where universal features\ndominate and finite size effects are small. For tethered chains in poor\nsolvent, we observe the predicted two-phase coexistence at transitions from the\nglobule to stretched conformations and also discover direct transitions from\ncrystalline to stretched conformations. A phase portrait for finite chains\nconstructed by evaluating the density of states for a broad range of solvent\nconditions and tensions shows how increasing tension leads to a disappearance\nof the globular phase. For chains in good solvents tethered to hard and\nattractive surfaces we find the predicted scaling with the chain length in the\nlow-force regime and show that our results are well described by an analytical,\nindependent-bond approximation for the bond-fluctuation model for the highest\ntensions. Finally, for a hard or slightly attractive surface the stretching of\na tethered chain is a conformational change that does not correspond to a phase\ntransition. However, when the surface attraction is sufficient to adsorb a\nchain it will undergo a desorption transition at a critical value of the\napplied force. Our results for force-induced desorption show the transition to\nbe discontinuous with partially desorbed conformations in the coexistence\nregion."
    },
    {
        "anchor": "Hydrogen bond correlated percolation in a supercooled water monolayer as\n  a hallmark of the critical region: Numerical simulations for a number of water models have supported the\npossibility of a metastable liquid-liquid critical point (LLCP) in the deep\nsuper-cooled region. Here we consider a theoretical model for a supercooled\nliquid water monolayer and its mathematical mapping onto a percolation problem.\nThe mapping allows us to identify the finite-size clusters at any state-point,\nand the infinite cluster at the critical point, with the regions of correlated\nhydrogen bonds (HBs). We show that the percolation line coincides with the\nfirst-order liquid-liquid phase transition ending at the LLCP. At pressures\nbelow the LLCP, the percolation line corresponds to the strong maxima of the\nthermodynamic response functions and to the locus of maximum correlation length\n(Widom line). At higher pressures, we find a percolation transition with a\npositive slope and we discuss its possible relation with the thermodynamics.",
        "positive": "Instabilities in droplets spreading on gels: We report a novel surface-tension driven instability observed for droplets\nspreading on a compliant substrate. When a droplet is released on the surface\nof an agar gel, it forms arms/cracks when the ratio of surface tension gradient\nto gel strength is sufficiently large. We explore a range of gel strengths and\ndroplet surface tensions and find that the onset of the instability and the\nnumber of arms depend on the ratio of surface tension to gel strength. However,\nthe arm length grows with an apparently universal law L ~ t^{3/4}."
    },
    {
        "anchor": "Effects of Non-local Stress on the Determination of Shear Banding Flow: We analyze the steady planar shear flow of the modified Johnson-Segalman\nmodel, which has an added non-local term. We find that the new term allows for\nunambiguous selection of the stress at which two ``phases'' coexist, in\ncontrast to the original model. For general differential constitutive models we\nshow the singular nature of stress selection in terms of a saddle connection\nbetween fixed points in the equivalent dynamical system. The result means that\nstress selection is unique under most conditions for space non-local models\nFinally, illustrated by simple models, we show that stress selection generally\ndepends on the form of the non-local terms (weak universality).",
        "positive": "On Eigenvalues and Eigenfunctions Absent in the Actual Solid State\n  Theory: In this letter new, closed and compact analytic expressions for the\nevaluation of resonant energies, resonant bound-states, eigenvalues and\neigenfunctions for both scattering and bounded $n$-cell systems are reported.\nIt is shown that for (scattering and bounded) 1-D systems the eigenfunctions\n$\\Psi_{\\mu ,\\nu}(z)$ are simple and well defined functions of the Chebyshev\npolynomials of the second kind $U_{n}$, and the energy eigenvalues $E_{\\mu ,\\nu\n}$ (in the $\\mu $-th band) are determined by the zeros of these polynomials.\nNew insights on the energy gap and the localization effect induced by phase\ncoherence are shown."
    },
    {
        "anchor": "Long-range correlations in pinned athermal networks: We derive exact results for displacement fields that develop as a response to\nexternal pinning forces in two dimensional athermal networks. For a triangular\nlattice arrangement of particles interacting through soft potentials, we\ndevelop a Green's function formalism which we use to derive exact results for\ndisplacement fields produced by localized external forces. We show that in the\ncontinuum limit the displacement fields decay as $1/r$ at large distances $r$\naway from a force dipole. Finally, we extend our formulation to study\ncorrelations in the displacement fields produced by the external pinning\nforces. We show that uncorrelated pinned forces at each vertex give rise to\nlong-range correlations in displacements in athermal systems, with a\nnon-trivial system size dependence. We verify our predictions with numerical\nsimulations of athermal networks in two dimensions.",
        "positive": "The Gaussian Diffusion Approximation for Complex Fluids is Generally\n  Invalid: Simulations are made of a probe particle diffusing through a complex fluid.\nProbe particle motions are described by the Mori-Zwanzig equation and Mori's\northogonal hierarchy of random forces scheme, subject to the approximation that\nthe fluid creates a rapidly-fluctuating random force corresponding to solvent\nmotions and a slowly fluctuating random force corresponding to solute (e.~g.,\nmatrix polymer) motions. The Gaussian diffusion approximation is seriously\nincorrect in this physically-plausible model system. $P(x,t)$ has exponential\nwings. $g^{(1s)}(q,t)$ can differ from $\\exp(-q^{2} \\langle x^{2}\\rangle/2)$ by\nup to orders of magnitude. Experimental interpretations that rely on the\nGaussian approximation, such as the Stejskal-Tanner equation for\npulsed-field-gradient NMR or particle tracking, can not be assumed to be\nreliable in complex fluids."
    },
    {
        "anchor": "Programmable Molecular Composites of Tandem Proteins with Graphene-Oxide\n  for Efficient Bimoprh Actuators: The rapid expansion in the spectrum of two-dimensional (2D) materials has\ndriven the efforts of research on the fabrication of 2D composites and\nheterostructures. Highly ordered structure of 2D materials provides an\nexcellent platform for controlling the ultimate structure and properties of the\ncomposite material with precision. However, limited control over the structure\nof the adherent material and its interactions with highly ordered 2D materials\nresults in defective composites with inferior performance. Here, we demonstrate\nthe successful synthesis, integration, and characterization of hybrid 2D\nmaterial systems consisting of tandem repeat (TR) proteins inspired by squid\nring teeth and graphene oxide (GO). The TR protein layer acts as a unique\nprogrammable molecular spacer between GO layers. As an application, we further\ndemonstrate thermal actuation using bimorph molecular composite films. Bimorph\nactuators made of molecular composite films (GO/TR) can lead to energy\nefficiencies 18 times higher than regular bimorph actuators consisting of a GO\nlayer and a TR protein layer (i.e., conventional bulk composite of GO and TR).\nAdditionally, molecular composite bimorph actuators can reach curvature values\nas high as 1.2 cm-1 by using TR proteins with higher molecular weight, which is\n3 times higher than conventional GO and TR composites.",
        "positive": "Epithelia are multiscale active liquid crystals: Biological processes such as embryogenesis, wound healing and cancer\nprogression, crucially rely on the ability of epithelial cells to coordinate\ntheir mechanical activity over length scales order of magnitudes larger than\nthe typical cellular size. While regulated by various signalling pathways, it\nhas recently become evident that this behavior can additionally hinge on a\nminimal toolkit of physical mechanisms, of which liquid crystal order is the\nmost prominent example. Yet, experimental and theoretical studies have given so\nfar inconsistent results in this respect: whereas nematic order is often\ninvoked in the interpretation of experimental data, computational models have\ninstead suggested that hexatic order could serve as a linchpin for collective\nmigration in confluent cell layers. In this article we resolve this dilemma.\nUsing a combination of in vitro experiments on Madin-Darby canine kidney cells\n(MDCK), numerical simulations and analytical work, we demonstrate that both\nnematic and hexatic order are, in fact, present in epithelial layers, with the\nformer being dominant at large length scales and the latter at small length\nscales. In MDCK GII cells on uncoated glass, these different types of liquid\ncrystal order crossover at a length scale of the order of ten cell sizes. Our\nwork sheds light on the emergent organization of living matter, provides a new\nframework for deciphering the structure of epithelia, and paves the way toward\na comprehensive and predictive mesoscopic theory of tissues."
    },
    {
        "anchor": "Effective attraction between like-charged colloids in a 2D plasma: The existence of attractions between like-charged colloids immersed in ionic\nsolution have been discovered in recent experiments. This phenomenon\ncontradicts the predictions of DLVO theory and indicates a failure of mean\nfield theory. We study a toy model based on a two dimensional one-component\nplasma, which is exactly soluble at one particular coupling constant. We show\nthat colloidal interaction results from a competition between ion-ion repulsion\nand longer ranged ion-void attraction.",
        "positive": "Non-Markovian dynamics of reaction coordinate in polymer folding: We develop a theoretical description of the critical zipping dynamics of a\nself-folding polymer. We use tension propagation theory and the formalism of\nthe generalized Langevin equation applied to a polymer that contains two\ncomplementary parts which can bind to each other. At the critical temperature,\nthe (un)zipping is unbiased and the two strands open and close as a zipper. The\nnumber of closed base pairs $n(t)$ displays a subdiffusive motion characterized\nby a variance growing as $\\langle \\Delta n^2(t) \\rangle \\sim t^\\alpha$ with\n$\\alpha < 1$ at long times. Our theory provides an estimate of both the\nasymptotic anomalous exponent $\\alpha$ and of the subleading correction term,\nwhich are both in excellent agreement with numerical simulations. The results\nindicate that the tension propagation theory captures the relevant features of\nthe dynamics and shed some new insights on related polymer problems\ncharacterized by anomalous dynamical behavior."
    },
    {
        "anchor": "Wetting of soft substrates: Within mean-field theory we study wetting of elastic substrates. Our analysis\nis based on a grand canonical free energy functional of the fluid number\ndensity and of the substrate displacement field. The substrate is described in\nterms of the linear theory of elasticity, parametrized by two Lam\\'e\ncoefficients. The fluid contribution is of the van der Waals type. Two\npotentials characterize the interparticle interactions in the system. The\nlong-ranged attraction between the fluid particles is described by a potential\n$w(r)$, and $v(r)$ characterizes the substrate-fluid interaction. By\nintegrating out the elastic degrees of freedom we obtain an effective theory\nfor the fluid number density alone. Its structure is similar to the one for\nwetting of an inert substrate. However, the potential $w(r)$ is replaced by an\neffective potential which, in addition to $w(r)$, contains a term bilinear in\n$v(r)$. We discuss the corresponding wetting transitions in terms of an\neffective interface potential $\\omega(\\ell)$, where $\\ell$ denotes the\nthickness of the wetting layer. We show that in the case of algebraically\ndecaying interactions the elasticity of the substrate may suppress critical\nwetting transitions, and may even turn them first order.",
        "positive": "Adsorption phenomena in the transport of a colloidal particle through a\n  nanochannel containing a partially wetting fluid: Using molecular dynamics simulations, we study the motion of a closely\nfitting nanometer-size solid sphere in a fluid-filled cylindrical nanochannel\nat low Reynolds numbers and for a wide range of fluid-solid interactions\ncorresponding to different wetting situations. For fluids that are not\ncompletely wetting we observe an interesting and novel adsorption phenomenon,\nin which the solid sphere, that was initially moving along the center of the\ntube, meanders across the channel and suddenly adsorbes onto the wall.\nThereafter, the adsorbed sphere either {\\it sticks} to the wall and remains\nmotionless on average, or separates slightly from the tube wall and then moves\nparallel to the tube axis, while rotating on average. On the other hand, at\nshort times, i.e. when the solid particle moves with its center close to the\nmiddle of the tube, we find surprisingly good agreement between our results and\nthe predictions of the continuum approach in spite of the large thermal\nfluctuations present in our simulations."
    },
    {
        "anchor": "Delays-induced Phase Transitions in Active Matter: We consider the patterns of collective motion emerging when many aligning,\nself-propelling units move in two dimensions while interacting through a\nrepulsive potential and are also subject to delays and random perturbations. In\nthis approach, delay plays the role analogous to reaction time so that a given\nparticle is influenced by the information about the velocity and the position\nof the other particles in its vicinity with some time delay. To get insight\ninto the involved complex flows and the transitions between them we use a\nsimple model allowing, by fine-tuning of its few parameters, the observation\nand analysis of behaviours that are less accessible by experiments or analytic\ncalculations and at the same time make the reproduction of experimental results\npossible. We report for the first time about a transition from an ordered,\npolarized collective motion to disorder as a function of the increasing time\ndelay. For a fixed intermediate value of the delay similar transition (from\norder to disorder) is obtained as the repulsion radius is increased. Our\nsimulations show a transition from total polarization to two kinds of states:\nfully disordered and a kind of state which is a mixture of patches of fully\ndisordered motion in the background of orderly moving other particles. The\ntransition occurs as the delay time is increased and is sharp, indicating that\nthe nature of this order-disorder transition is either of first-order or is\ndescribed by a sharply decreasing linear function. Our model is a simplified\nversion of a practical situation of quickly growing interest because time\ndelays are expected to play an increasingly important role when the traffic of\nmany, densely distributed autonomous drones will move around in a\nquasi-two-dimensional air space.",
        "positive": "Macromolecular Dynamics. An introductory lecture: This lecture has the following sections: Systems and States; Brownian Motion;\nSegmental Relaxation and the Glass Transition; Dynamics of a Free Chain;\nEntanglement and Reptation. Appendices cover: Linear response theory,\nrelaxation, dissipation, fluctuation; Debye's theory of dielectric relaxation;\nZimm's theory of chain dynamics in solution."
    },
    {
        "anchor": "A simple model for viscoelastic crack propagation: When a crack propagate in a viscoelastic solid energy dissipation can occur\nvery far from the crack tip where the stress field may be very different from\nthe $r^{-1/2}$ singular form expected close to the crack tip. Most theories of\ncrack propagation focus on the near crack-tip region. Remarkable, here I show\nthat a simple theory which does not account for the nature of the stress field\nin the near crack-tip region result in a crack propagation energy in\nsemi-quantitative agreement with a theory based on the stress field in the near\ncrack-tip region. I consider both opening and closing crack propagation, and\nshow that for closing crack propagation in viscoelastic solids, some energy\ndissipation processes must occur in thecrack tip process zone.",
        "positive": "The non-Gaussian tops and tails of diffusing boomerangs: Experiments involving the two-dimensional passive diffusion of colloidal\nboomerangs tracked off their centre of mobility have shown striking\nnon-Gaussian tails in their probability distribution function [Chakrabarty et\nal., Soft Matter 12, 4318 (2016)]. This in turn can lead to anomalous diffusion\ncharacteristics, including mean drift. In this paper, we develop a general\ntheoretical explanation for these measurements. The idea relies on calculating\nthe two-dimensional probability densities at the centre of mobility of the\nparticle, where all distributions are Gaussian, and then transforming them to a\ndifferent reference point. Our model clearly captures the experimental results,\nwithout any fitting parameters, and demonstrates that the one-dimensional\nprobability distributions may also exhibit strongly non-Gaussian tops. These\nresults indicate that the choice of tracking point can cause a considerable\ndeparture from Gaussian statistics, potentially causing some common modelling\ntechniques to fail."
    },
    {
        "anchor": "Flow profiling of a surface acoustic wave nanopump: The flow profile in a capillary gap and the pumping efficiency of an acoustic\nmicropump employing Surface Acoustic Waves is investigated both experimentally\nand theoretically. Such ultrasonic surface waves on a piezoelectric substrate\nstrongly couple to a thin liquid layer and generate an internal streaming\nwithin the fluid. Such acoustic streaming can be used for controlled agitation\nduring, e.g., microarray hybridization. We use fluorescence correlation\nspectroscopy and fluorescence microscopy as complementary tools to investigate\nthe resulting flow profile. The velocity was found to depend on the applied\npower somewhat weaker than linearly and to decrease fast with the distance from\nthe ultrasound generator on the chip.",
        "positive": "New version of the fluctuation Hamiltonian for liquids near the critical\n  point: We propose new canonical form of the fluctuational Hamiltonian which takes\ninto account the fact that in the vicinity of the critical point there are two\nfluctuating fields. They are the field of the number density and the entropy.\nThe proposed canonical form is based on the $D_5$ catastrophe. In contrast to\nthe standard approach of Landau-Ginzburg Hamiltonian which is based on $A_3$\ncatastrophe the canonical form proposed for the fluctuational Hamiltonian\nnaturally includes the asymmetric coupling between the fields."
    },
    {
        "anchor": "Self-assembly of orthorhombic Fddd network in simple one-component\n  liquids: Triply periodic continuous morphologies arising a result of the microphase\nseparation in block copolymer melts have so far never been observed\nself-assembled in systems of particles with spherically symmetric interaction.\nWe report a molecular dynamics simulation of two simple one-component liquids\nwhich self-assemble upon cooling into equilibrium orthorhombic continuous\nnetwork morphologies with the Fddd space group symmetry reproducing the\nstructure of those observed in block copolymers. The finding that the geometry\nof constituent molecules isn't relevant for the formation of triply periodic\nnetworks indicates the generic nature of this class of phase transition.",
        "positive": "Deformation Decomposition versus Energy Decomposition for Chemo- and\n  Poro- Mechanics: We briefly compare the structure of two classes of popular models used to\ndescribe poro- and chemo- mechanics wherein a fluid phase is transported within\na solid phase. The multiplicative deformation decomposition has been\nsuccessfully used to model permanent inelastic shape change in plasticity,\nsolid-solid phase transformation, and thermal expansion, which has motivated\nits application to poro- and chemo- mechanics. However, the energetic\ndecomposition provides a more transparent structure and advantages, such as to\ncouple to phase-field fracture, for models of poro- and chemo- mechanics."
    },
    {
        "anchor": "Time-dependent Nonlinear Optical Susceptibility of an Out-of-Equilibrium\n  Soft Material: We investigate the time-dependent nonlinear optical absorption of a clay\ndispersion (Laponite) in organic dye (Rhodamine B) water solution displaying\nliquid-arrested state transition. Specifically, we determine the characteristic\ntime $\\tau_D$ of the nonlinear susceptibility build-up due as to the Soret\neffect. By comparing $\\tau_D$ with the relaxation time provided by standard\ndynamic light scattering measurements we report on the decoupling of the two\ncollective diffusion times at the two very different length scales during the\naging of the out-of-equilibrium system. With this demonstration experiment we\nalso show the potentiality of nonlinear optics measurements in the study of the\nlate stage of arrest in soft materials.",
        "positive": "Sol-gel transition induced by alumina nanoparticles in a model pulmonary\n  surfactant: Inhaled airborne particles smaller than 100 nm entering the airways have been\nshown to deposit in significant amount in the alveolar region of the lungs. The\ninterior of the alveoli is covered with a ~ 1 micron thick lining fluid, called\npulmonary surfactant. Inhaled nanoparticles are susceptible to interact with\nthe lung fluid and modify pulmonary functions. Here we evaluate the structural\nand rheological properties of the pulmonary surfactant substitute Curosurf\nwhich is administered to premature babies for the treatment of respiratory\ndistress syndrome. Curosurf is considered a reliable model of endogenous\npulmonary surfactant in terms of composition, structure and function. Using\nactive microrheology based on magnetically actuated wires, we find that\nCurosurf dispersions exhibit a Newtonian behavior at lipid concentration from 0\nto 80 g L-1, and that the viscosity follows the Krieger-Dougherty law observed\nfor a wide variety of colloids. Upon addition of 40 nm alumina nanoplatelets, a\nsignificant change of the Curosurf rheology is noticed. The dispersions then\nenter a soft solid phase characterized by an infinite viscosity and a non-zero\nequilibrium elastic modulus. The sol-gel transition induced by the\nnanoparticles is interpreted as the result of the alumina/vesicle interaction,\nwhich are illustrated by transmission electron microscopy. It also suggests a\npotential toxicity associated with the modification of the lung fluid\nstructural and dynamical properties."
    },
    {
        "anchor": "Stretching, Twisting and Supercoiling in Short, Single DNA Molecules: We had combined the Neukirch-Marko model that describes the extension, torque\nand supercoiling in single, stretched and twisted DNA of infinite contour\nlength, with a form of the free energy suggested by Sinha and Samuels to\ndescribe short DNA, with contour length only a few times the persistence\nlength. We find that the free energy of the stretched but untwisted DNA, is\nsignificantly modified from its infinitely length value and this in turn\nmodifies significantly the torque and supercoiling. We show that this is\nconsistent with short DNA being more flexible than infinitely long DNA. We hope\nour results will stimulate experimental investigation of torque and\nsupercoiling in short DNA.",
        "positive": "Accelerated drop detachment in granular suspensions: We experimentally study the detachment of drops of granular suspensions using\na density matched model suspension with varying volume fraction ({\\phi} = 15%\nto 55%) and grain diameter (d = 20 {\\mu}m to 140 {\\mu}m). We show that at the\nbeginning of the detachment process, the suspensions behave as an effective\nfluid. The detachment dynamics in this regime can be entirely described by the\nshear viscosity of the suspension. At later stages of the detachment the\ndynamics become independent of the volume fraction and are found to be\nidentical to the dynamics of the interstitial fluid. Surprisingly, visual\nobservation reveals that at this stage particles are still present in the neck.\nWe suspect rearrangements of particles to locally free the neck of grains,\ncausing the observed dynamics. Close to the final pinch off, the detachment of\nthe suspensions is further accelerated, compared to the dynamics of pure\ninterstitial fluid. This acceleration might be due to the fact that the neck\ndiameter gets of the order of magnitude of the size of the grains and a\ncontinuous thinning of the liquid thread is not possible any more. The\ncrossover between the different detachment regimes is function of the grain\nsize and the initial volume fraction. We characterize the overall acceleration\nas a function of the grain size and volume fraction."
    },
    {
        "anchor": "Phenomenology and physical origin of shear-localization and\n  shear-banding in complex fluids: We review and compare the phenomenological aspects and physical origin of\nshear-localization and shear-banding in various material types, namely\nemulsions, suspensions, colloids, granular materials and micellar systems. It\nappears that shear-banding, which must be distinguished from the simple effect\nof coexisting static-flowing regions in yield stress fluids, occurs in the form\nof a progressive evolution of the local viscosity towards two significantly\ndifferent values in two adjoining regions of the fluids in which the stress\ntakes slightly different values. This suggests that from a global point of view\nshear-banding in these systems has a common physical origin: two physical\nphenomena (for example, in colloids, destructuration due to flow and\nrestructuration due to aging) are in competition and, depending on the flow\nconditions, one of them becomes dominant and makes the system evolve in a\nspecific direction.",
        "positive": "Enhancement by polydispersity of the biaxial nematic phase in a mixture\n  of hard rods and plates: The phase diagram of a polydisperse mixture of uniaxial rod-like and\nplate-like hard parallelepipeds is determined for aspect ratios $\\kappa=5$ and\n15. All particles have equal volume and polydispersity is introduced in a\nhighly symmetric way. The corresponding binary mixture is known to have a\nbiaxial phase for $\\kappa=15$, but to be unstable against demixing into two\nuniaxial nematics for $\\kappa=5$. We find that the phase diagram for\n$\\kappa=15$ is qualitatively similar to that of the binary mixture, regardless\nthe amount of polydispersity, while for $\\kappa=5$ a sufficient amount of\npolydispersity stabilizes the biaxial phase. This provides some clues for the\ndesign of an experiment in which this long searched biaxial phase could be\nobserved."
    },
    {
        "anchor": "Active Cytoskeletal Composites Display Emergent Tunable Contractility\n  and Restructuring: The cytoskeleton is a model active matter system that controls diverse\ncellular processes from division to motility. While both active actomyosin\ndynamics and actin-microtubule interactions are key to the cytoskeleton's\nversatility and adaptability, an understanding of their interplay is lacking.\nHere, we couple microscale experiments with mechanistic modeling to elucidate\nhow connectivity, rigidity, and force-generation affect emergent material\nproperties in in vitro composites of actin, tubulin, and myosin. We use\ntime-resolved differential dynamic microscopy and spatial image autocorrelation\nto show that ballistic contraction occurs in composites with sufficient\nflexibility and motor density, but that a critical fraction of microtubules is\nnecessary to sustain controlled dynamics. Our active double-network models\nreveal that percolated actomyosin networks are essential for contraction, but\nthat networks with comparable actin and microtubule densities can uniquely\nresist mechanical stresses while simultaneously supporting substantial\nrestructuring. Our findings provide a much-needed blueprint for designing\ncytoskeleton-inspired materials that couple tunability with resilience and\nadaptability.",
        "positive": "Pulsed Quantum Tunneling with Matter Waves: In this report we investigate the macroscopic quantum tunneling of a Bose\ncondensate falling under gravity and scattering on a Gaussian barrier that\ncould model a mirror of far-detuned sheet of light. We analyze the effect of\nthe inter-atomic interaction and that of a transverse confining potential. We\nshow that the quantum tunneling can be quasi-periodic and in this way one could\ngenerate coherent Bose condensed atomic pulses. In the second part of the\nreport, we discuss an effective 1D time-dependent non-polynomial nonlinear\nSchrodinger equation (NPSE), which describes cigar-shaped condensates. NPSE is\nobtained from the 3D Gross-Pitaevskii equation by using a variational approach.\nWe find that NPSE gives much more accurate results than all other effective 1D\nequations recently proposed."
    },
    {
        "anchor": "Power-law intermittency in the gradient-induced self-propulsion of\n  colloidal swimmers: Active colloidal microswimmers serve as archetypical active fluid systems,\nand as models for biological swimmers. Here, by studying in detail their\nvelocity traces, we find robust power-law intermittency with system-dependent\nexponential cut off. We model the motion by an interplay of the field\ngradient-dependent active force and the locally fluctuating hydrodynamic drag,\nset by the wetting properties of the substrate. The model closely describes the\nvelocity distributions of two disparate swimmer systems: AC field activated and\ncatalytic swimmers. The generality is highlighted by the collapse of all data\nin a single master curve, suggesting the applicability to further systems, both\nsynthetic and biological.",
        "positive": "Topological Solitons in Helical Strings: The low-energy physics of (quasi)degenerate one-dimensional systems is\ntypically understood as the particle-like dynamics of kinks between stable,\nordered structures. Such dynamics, we show, becomes highly non-trivial when the\nground states are topologically constrained: a dynamics of the domains rather\nthan on the domains which the kinks separate. Motivated by recently reported\nobservations of charged polymers physisorbed on nanotubes, we study kinks\nbetween helical structures of a string wrapping around a cylinder. While their\nmotion cannot be disentangled from domain dynamics, and energy and momentum is\nnot concentrated in the solitons, the dynamics of the domains can be folded\nback into a one-particle picture."
    },
    {
        "anchor": "Hydrogen bonding and coordination in normal and supercritical water from\n  X-ray inelastic scattering: A direct measure of hydrogen bonding in water under conditions ranging from\nthe normal state to the supercritical regime is derived from the Compton\nscattering of inelastically-scattered X-rays. First, we show that a measure of\nthe number of electrons $n_e$ involved in hydrogen bonding at varying\nthermodynamic conditions can be directly obtained from Compton profile\ndifferences. Then, we use first-principles simulations to provide a connection\nbetween $n_e$ and the number of hydrogen bonds $n_{HB}$. Our study shows that\nover the broad range studied the relationship between $n_e$ and $n_{HB}$ is\nlinear, allowing for a direct experimental measure of bonding and coordination\nin water. In particular, the transition to supercritical state is characterized\nby a sharp increase in the number of water monomers, but also displays a\nsignificant number of residual dimers and trimers.",
        "positive": "Training nonlinear elastic functions: nonmonotonic, sequence dependent\n  and bifurcating: The elastic behavior of materials operating in the linear regime is\nconstrained, by definition, to operations that are linear in the imposed\ndeformation. Though the nonlinear regime holds promise for new functionality,\nthe design in this regime is challenging. In this paper we demonstrate that a\nrecent approach based on training [Hexner et al., PNAS 2020, 201922847] allows\nresponses that are inherently non-linear. By applying designer strains, a\ndisordered solids evolves through plastic deformations that alter its response.\nWe show examples of elaborate nonlinear training paths that lead to the\nfollowing functions: (1) Frequency conversion (2) Logic gate and (3) Expansion\nor contraction along one axis, depending on the sequence of imposed transverse\ncompressions. We study the convergence rate and find that it depends on the\ntrained function."
    },
    {
        "anchor": "A Statistical Model of Pressure Drop Increase with Deposition in\n  Granular Filters: As deposits accumulate in a granular filter, pressure drop across the filter\nbed required to maintain a constant fluid flow rate may increase. Two pressure\ndrop increase patterns had been observed. In slow sand filters pressure drop\nremains unchanged for a certain period of time then increases exponentially\nwith the volume of filtrate; in granular aerosol filters pressure drop\nincreases linearly with the amount of deposits from the beginning of the\nfiltration process. New concepts of homogeneous and heterogeneous depositions\nwere introduced in this paper. A statistical model based on these new concepts\nwas developed. This non-linear model was able to reproduce both observed\npressure drop increase patterns, including the linear one. Excellent agreements\nbetween the present model and experimental measurements were obtained. It was\nconcluded that the two pressure drop increase patterns were indeed caused by\ndifferent deposit distributions rather than different pressure drop increase\nmechanisms.",
        "positive": "Freezing and melting equations for the $n$-6 Lennard-Jones systems: We generalize previous approach of Khrapak and Morfill [J. Chem. Phys. {\\bf\n134}, 094108 (2011)] to construct simple and sufficiently accurate freezing and\nmelting equations for the conventional Lennard-Jones (LJ) system to $n$-6 LJ\nsystems, using the accurate results for the triple points of these systems\npublished by Sousa {\\it et al.} [J. Chem. Phys. {\\bf 136}, 174502 (2012)]."
    },
    {
        "anchor": "A simulation method for the wetting dynamics of liquid droplets on\n  deformable membranes: Biological cells utilize membranes and liquid-like droplets, known as\nbiomolecular condensates, to structure their interior. The interaction of\ndroplets and membranes, despite being involved in several key biological\nprocesses, is so far little understood. Here, we present a first numerical\nmethod to simulate the continuum dynamics of droplets interacting with\ndeformable membranes via wetting. The method combines the advantages of the\nphase-field method for multi-phase flow simulation and the arbitrary\nLagrangian-Eulerian (ALE) method for an explicit description of the elastic\nsurface. The model is thermodynamically consistent, coupling bulk hydrodynamics\nwith capillary forces, as well as bending, tension, and stretching of a thin\nmembrane. The method is validated by comparing simulations for single droplets\nto theoretical results of shape equations, and its capabilities are illustrated\nin 2D and 3D axisymmetric scenarios.",
        "positive": "Competition between Born solvation, dielectric exclusion, and Coulomb\n  attraction in spherical nanopores: The recent measurement of a very low dielectric constant, $\\epsilon$, of\nwater confined in nanometric slit pores leads us to reconsider the physical\nbasis of ion partitioning into nanopores. For confined ions in chemical\nequilibrium with a bulk of dielectric constant $\\epsilon_b>\\epsilon$, three\nphysical mechanisms, at the origin of ion exclusion in nanopores, are expected\nto be modified due to this dielectric mismatch: dielectric exclusion at the\nwater-pore interface (with membrane dielectric constant,\n$\\epsilon_m<\\epsilon$), the solvation energy related to the difference in\nDebye-H\\\"uckel screening parameters in the pore, $\\kappa$, and in the bulk\n$\\kappa_b$, and the classical Born solvation self-energy proportional to\n$\\epsilon^{-1}-\\epsilon_b^{-1}$. Our goal is to clarify the interplay between\nthese three mechanisms and investigate the role played by the Born contribution\nin ionic liquid-vapor (LV) phase separation in confined geometries. We first\ncompute analytically the potential of mean force (PMF) of an ion of radius\n$R_i$ located at the center of a nanometric spherical pore of radius $R$.\nComputing the variational grand potential for a solution of confined ions, we\nthen deduce the partition coefficients of ions in the pore. Phase diagrams of\nthe LV transition are established for various parameter values and we show that\na signature of this phase transition can be detected by monitoring the total\nosmotic pressure. For charged nanopores, these exclusion effects compete with\nthe electrostatic attraction that imposes the entry of counterions into the\npore to enforce electro-neutrality. This study will therefore help in\ndeciphering the respective roles of the Born self-energy and dielectric\nmismatch in experiments and simulations of ionic transport through nanopores."
    },
    {
        "anchor": "Comment to \"Multipolar expansion of the electrostatic interaction\n  between charged colloids at interfaces\": We present a comment to a recent paper by Dominguez et. al. They claimed that\nthe electrostatic interaction between charged colloids trapped at an interface\nformed by a dielectric and a screening phase is always isotropic to order\n$d^-3$. Base on this result, they claimed that in-plane dipolar attraction of\norder $d^-3$ between colloids cannot exist, in contrast to previous proposals.\nWe point out that their analysis is not completed and anisotropic (dipolar)\ninteraction between colloids can exist up to order $d^-3$.",
        "positive": "Quantitatively Connecting Experimental\n  Time-Temperature-Superposition-Breakdown of Polymers near the Glass\n  Transition to Dynamic Heterogeneity via the Heterogeneous Rouse Model: Polymers near the glass transition temperature Tg often exhibit a breakdown\nof time-temperature-superposition (TTS), with chain relaxation times and\nviscosity exhibiting a weaker temperature dependence than segmental relaxation\ntimes. The origin of this onset of thermorheological complexity has remained\nunsettled and a matter of debate. Here we extend the Heterogeneous Rouse Model\n(HRM), which generalizes the Rouse model to account for dynamic heterogeneity,\nto make predictions for the relaxation modulus G(t) and complex modulus\nG*($\\omega$) of unentangled polymers near Tg. The HRM predicts that G(t) and\nG*($\\omega$) exhibit enhanced effective scaling exponents in the Rouse regime\nin the presence of dynamic heterogeneity, with a more rapid decay from the\nglassy plateau emerging as the system becomes more dynamically heterogeneous on\ncooling. This behavior is predicted to emerge from a strand-length dependence\nof the moment of the segmental mobility distribution probed by chain dynamics.\nWe show that the HRM predictions are in good accord with experimental complex\nmodulus data for polystyrene, poly(methyl methacrylate), and poly(2-vinyl\npyridine). The HRM also predicts the onset of distinct temperature dependences\namong chain scale quantities such as terminal relaxation time and viscosity in\nour experimental systems, apparently resolving one of the most significant\nstanding objections to a heterogeneity-based origin of TTS-breakdown. The HRM\nthus provides a generalized theory of the chain-scale linear rheological\nresponse of unentangled polymers near Tg, accounting for the origin of\nTTS-breakdown at a molecular mechanistic level. It also points towards a new\nstrategy of inferring the dynamic heterogeneity of glass-forming polymeric\nsystems based on the temperature-evolution of modified scaling in the Rouse\nregime."
    },
    {
        "anchor": "Self-Assembled Chiral Photonic Crystals From Colloidal Helices Racemate: Chiral crystals consisting of micro-helices have many optical properties\nwhile presently available fabrication processes limit their large-scale\napplications in photonic devices. Here, by using a simplified simulation\nmethod, we investigate a bottom-up self-assembly route to build up helical\ncrystals from the smectic monolayer of colloidal helices racemate. With\nincreasing the density, the system undergoes an entropy-driven\nco-crystallization by forming crystals of various symmetries with different\nhelical shapes. In particular, we identify two crystals of helices arranged in\nthe binary honeycomb and square lattices, which are essentially composed by two\nsets of opposite-handed chiral crystal. Photonic calculations show that these\nchiral structures can have large complete photonic bandgaps. In addition, in\nthe self-assembled chiral square crystal, we also find dual polarization\nbandgaps that selectively forbid the propagation of circularly polarized lights\nof a specific handedness along the helical axis direction. The self-assembly\nprocess in our proposed system is robust, suggesting possibilities of using\nchiral colloids to assemble photonic metamaterials.",
        "positive": "Unjamming strongly compressed particle rafts: We experimentally study the unjamming dynamics of strongly compressed\nparticle rafts confined between two fixed walls and two movable barriers. The\nback barrier is made of an elastic band, whose deflection indicates the local\nstress. The front barrier is pierced by a gate, whose opening triggers local\nunjamming. The rafts are compressed by moving only one of the two barriers in\nthe vicinity of which folds form. Using high speed imaging, we follow the\nfolded, jammed, and unjammed raft areas and measure the velocity fields inside\nand outside of the initially confined domain. Two very different behaviors\ndevelop. For rafts compressed by the back barrier, only partial unjamming\noccurs. At the end of the process, many folds remain and the back stress does\nnot relax. The flow develops only along the compression axis and the particles\npassing the gate form a dense raft whose width is the gate width. For rafts\ncompressed at the front, quasi-total unjamming is observed. No folds persist\nand only minimal stress remains, if any. The particles flow along the\ncompression axis but also normally to it and form, after the gate, a rather\ncircular and not dense assembly. We attribute this difference to the opposite\norientation of the force chain network that builds up from the compressed side\nand branchs. For rafts compressed at the gate side, keystone particles are\nimmediately removed which enhances local disentanglement and leads to large\nscale unjamming. In contrast, for back compressed rafts, the force chain\nnetwork redirects the stress laterally forming arches around the gate and\nresulting in a limited unjamming process."
    },
    {
        "anchor": "Ferroelectric nematic -- isotropic critical end point: A critical end point above which an isotropic phase continuously evolves into\na polar (ferroelectric) nematic phase with an increasing electric field is\nfound in a ferroelectric nematic liquid crystalline material. The critical end\npoint is approximately 30 K above the zero-field transition temperature from\nthe isotropic to nematic phase and at an electric field of the order of 10\nV/micron. Such systems are interesting from the application point of view\nbecause a strong birefringence can be induced in a broad temperature range in\nan optically isotropic phase.",
        "positive": "Thermal decomposition of a honeycomb-network sheet - A Molecular\n  Dynamics simulation study: The thermal degradation of a graphene-like two-dimensional triangular\nmembrane with bonds undergoing temperature-induced scission is studied by means\nof Molecular Dynamics simulation using Langevin thermostat. We demonstrate that\nthe probability distribution of breaking bonds is highly peaked at the rim of\nthe membrane sheet at lower temperature whereas at higher temperature bonds\nbreak at random anywhere in the hexagonal flake. The mean breakage time $\\tau$\nis found to decrease with the total number of network nodes $N$ by a power law\n$\\tau \\propto N^{-0.5}$ and reveals an Arrhenian dependence on temperature $T$.\nScission times are themselves exponentially distributed. The fragmentation\nkinetics of the average number of clusters can be described by first-order\nchemical reactions between network nodes $n_i$ of different coordination. The\ndistribution of fragments sizes evolves with time elapsed from a\n$\\delta$-function through a bimodal one into a single-peaked again at late\ntimes. Our simulation results are complemented by a set of $1^{st}$-order\nkinetic differential equations for $n_i$ which can be solved exactly and\ncompared to data derived from the computer experiment, providing deeper insight\ninto the thermolysis mechanism."
    },
    {
        "anchor": "Plugs in rough capillary tubes: enhanced dependence of motion on plug\n  length: We discuss the creeping motion of plugs of negligible viscosity in rough\ncapillary tubes filled with carrier fluids. This extends Bretherton's research\nwork on the infinite-length bubble motion in a cylindrical or smooth tube for\nsmall capillary numbers Ca. We first derive the asymptotic dependence of the\nplug speed on the finite length in the smooth tube case. This dependence on\nlength is exponentially small, with a decay length much shorter than the tube\nradius R. Then we discuss the effect of azimuthal roughness of the tube on the\nplug speed. The tube roughness leads to an unbalanced capillary pressure and a\ncarrier fluid flux in the azimuthal plane. This flux controls the relaxation of\nthe plug shape to its infinite-length limit. For long-wavelength roughness, we\nfind that the above decay length is much longer in the rough tube, and even\nbecomes comparable to the tube radius R in some cases. This implies a\nmuch-enhanced dependence of the plug speed on the plug length. This mechanism\nmay explain the catch-up effect seen experimentally.",
        "positive": "Researh Note: Stokes-Einstein relation in simple fluids revisited: In this Research Note the Zwanzig's formulation of the Stokes-Einstein (SE)\nrelation for simple atomistic fluids is re-examined. It is shown that the value\nof the coefficient in SE relation depends on the ratio of the transverse and\nlongitudinal sound velocities. In some cases, this ratio can be directly\nrelated to the pair interaction potential operating in fluids and thus there\ncan be a certain level of predictivity regarding the value of this coefficient.\nThis Research Note provides some evidence in favour of this observation. In\nparticular, analyzing the situation in several model systems such as\none-component plasma, Yukawa, inverse-power-law, Lennard-Jones, and hard-sphere\nfluids, it is demonstrated that there are certain correlations between the\ninteraction softness and the coefficient in SE relation. The SE coefficient is\nalso re-evaluated for various liquid metals at the melting temperature, for\nwhich necessary data are available."
    },
    {
        "anchor": "Dynamically turning off interactions in a two component condensate: We propose a mechanism to change the interaction strengths of a two component\ncondensate. It is shown that the application of pi/2 pulses allows to alter the\neffective interspecies interaction strength as well as the effective\ninteraction strength between particles of the same kind. This mechanism\nprovides a simple method to transform spatially stable condensates into\nunstable once and vice versa. It also provides a means to store a squeezed spin\nstate by turning off the interaction for the internal states and thus allows to\ngain control over many body entangled states.",
        "positive": "Impact of Ultrasound on the Motion of Compact Particles and\n  Acousto-responsive Microgels: In this study, we investigate dynamic light scattering (DLS) from both\nrandomly diffusing silica particles and acousto-responsive microgels in aqueous\ndispersions under ultrasonic vibration. Employing high-frequency ultrasound\n(US) with low amplitude ensures that the polymers remain intact without damage.\nWe derive theoretical expressions for the homodyne autocorrelation function,\nincorporating the US term alongside the diffusion term. Subsequently, we\nsuccessfully combine US with a conventional DLS system to experimentally\ncharacterize compact silica particles and microgels under the influence of US.\nOur model allows us to extract essential parameters, including particle size,\nfrequency, and amplitude of particle vibration, based on the correlation\nfunction of the scattered light intensity. The studies involving non-responsive\nsilica particles demonstrate that US does not disrupt size determination,\nestablishing them as suitable reference systems. Microgels show the same\nswelling/shrinking behavior as that induced by temperature, but with\nsignificantly faster kinetics. The findings of this study have potential\napplications in various industrial and biomedical fields that benefit from the\ncharacterization of macromolecules subjected to US."
    },
    {
        "anchor": "Flow induced crystallization of penetrable particles: For a system of Brownian particles interacting via a soft exponential\npotential we investigate the interaction between equilibrium crystallization\nand spatially varying shear flow. For thermodynamic state points within the\nliquid part of the phase diagram, but close to the crystallization phase\nboundary, we observe that imposing a Poiseuille flow can induce nonequilibrium\ncrystalline ordering in regions of low shear gradient. The physical mechanism\nresponsible for this phenomenon is shear induced particle migration, which\ncauses particles to drift preferentially towards the center of the flow\nchannel, thus increasing the local density in the channel center. The method\nemployed is classical dynamical density functional theory.",
        "positive": "Environmental bias and elastic curves on surfaces: The behavior of an elastic curve bound to a surface will reflect the geometry\nof its environment. This may occur in an obvious way: the curve may deform\nfreely along directions tangent to the surface, but not along the surface\nnormal. However, even if the energy itself is symmetric in the curve's geodesic\nand normal curvatures, which control these modes, very distinct roles are\nplayed by the two. If the elastic curve binds preferentially on one side, or is\nitself assembled on the surface, not only would one expect the bending moduli\nassociated with the two modes to differ, binding along specific directions,\nreflected in spontaneous values of these curvatures, may be favored. The shape\nequations describing the equilibrium states of a surface curve described by an\nelastic energy accommodating environmental factors will be identified by\nadapting the method of Lagrange multipliers to the Darboux frame associated\nwith the curve. The forces transmitted to the surface along the surface normal\nwill be determined. Features associated with a number of different energies,\nboth of physical relevance and of mathematical interest, are described. The\nconservation laws associated with trajectories on surface geometries exhibiting\ncontinuous symmetries are also examined."
    },
    {
        "anchor": "Simulation of colloidal chain movements under a magnetic field: Short colloidal chains are simulated by the slithering-snake-algorithm on a\nsimple cubic lattice. The dipole character of the colloidal particles leads to\na long range dipole-dipole interaction. The solvent is simulated by the nearest\nneighbor Ising model. The aligning of the dipoles under a magnetic field gives\nrise to the chains to align on their part with the field direction.",
        "positive": "Disordered multihyperuniformity derived from binary plasmas: Disordered multihyperuniform many-particle systems are exotic amorphous\nstates that allow exquisite color sensing capabilities due to their anomalous\nsuppression of density fluctuations for distinct subsets of particles, as\nrecently evidenced in photoreceptor mosaics in avian retina. Motivated by this\nbiological finding, we present the first statistical-mechanical model that\nrigorously achieves disordered multihyperuniform many-body systems by tuning\ninteractions in binary mixtures of non-additive hard-disk plasmas. We\ndemonstrate that multihyperuniformity competes with phase separation and\nstabilizes a clustered phase. Our work provides a systematic means to generate\ndisordered multihyperuniform solids, enabling one to explore their potentially\nnovel photonic, phononic, electronic and transport properties."
    },
    {
        "anchor": "How Confinement-Induced Structures Alter the Contribution of\n  Hydrodynamic and Short-Ranged Repulsion Forces to the Viscosity of Colloidal\n  Suspensions: Understanding the correlation between structure and rheology in colloidal\nsuspensions is important as these suspensions are crucial in industrial\napplications. Moreover, colloids exhibit a wide range of structures under\nconfinement that could considerably alter the viscosity. Here, we use a\ncombination of experiments and simulations to elucidate how confinement induced\nstructures alter the relative contributions of hydrodynamic and repulsive\nforces to produce up to a ten fold change in the viscosity. We use a custom\nbuilt confocal rheoscope to image the particle configurations of a colloidal\nsuspension while simultaneously measuring the viscosity. We find a\nnon-monotonic trend to the viscosity under confinement that is strongly\ncorrelated with the microstructure. As the gap decreases below 15 particle\ndiameters, the viscosity first decreases from its bulk value, shows\nfluctuations with the gap, and then sharply increases for gaps below three\nparticle diameters. Further, we compare our experimental results to two\nsimulations techniques that enables us to determine the relative contributions\nof hydrodynamic and short range repulsive stresses. The first method uses the\nlubrication approximation to find the hydrodynamic stress and includes a short\nrange repulsive force between the particles and the second is a Stokesian\ndynamics simulation that calculates the full hydrodynamic stress in the\nsuspension. We find that the decrease in the viscosity at moderate confinements\nhas a significant contribution from both the hydrodynamic and repulsive forces\nwhereas the increase in viscosity at gaps less than three particle diameters\narises primarily from short range repulsive forces. These results provide new\ninsights to the unique rheological behavior of confined suspensions and further\nenable us to tune the viscosity by changing properties such as the gap,\npolydispersity, and the volume fraction.",
        "positive": "Mechanical instability at finite temperature: Many physical systems including lattices near structural phase transitions,\nglasses, jammed solids, and bio-polymer gels have coordination numbers that\nplace them at the edge of mechanical instability. Their properties are\ndetermined by an interplay between soft mechanical modes and thermal\nfluctuations. In this paper we investigate a simple square-lattice model with a\n$\\phi^4$ potential between next-nearest-neighbor sites whose quadratic\ncoefficient $\\kappa$ can be tuned from positive negative. We show that its\nzero-temperature ground state for $\\kappa <0$ is highly degenerate, and we use\nanalytical techniques and simulation to explore its finite temperature\nproperties. We show that a unique rhombic ground state is entropically favored\nat nonzero temperature at $\\kappa <0$ and that the existence of a subextensive\nnumber of \"floppy\" modes whose frequencies vanish at $\\kappa = 0$ leads to\nsingular contributions to the free energy that render the square-to-rhombic\ntransition first order and lead to power-law behavior of the shear modulus as a\nfunction of temperature. We expect our study to provide a general framework for\nthe study of finite-temperature mechanical and phase behavior of other systems\nwith a large number of floppy modes."
    },
    {
        "anchor": "Testing the relevance of effective interaction potentials between highly\n  charged colloids in suspension: Combining cell and Jellium model mean-field approaches, Monte Carlo together\nwith integral equation techniques, and finally more demanding many-colloid\nmean-field computations, we investigate the thermodynamic behavior, pressure\nand compressibility of highly charged colloidal dispersions, and at a more\nmicroscopic level, the force distribution acting on the colloids. The\nKirkwood-Buff identity provides a useful probe to challenge the\nself-consistency of an approximate effective screened Coulomb (Yukawa)\npotential between colloids. Two effective parameter models are put to the test:\ncell against renormalized Jellium models.",
        "positive": "Effects of confinement on the dynamics and correlation scales in active\n  fluids: We study the influence of solid boundaries on dynamics and structure of\nactive fluids as the height of the container, $z$, changes. Along the varying\ndimension, the geometry systematically increases, therefore, the confinement\n($z$) transits from \"strong confinement\", to \"intermediate confinement\" and to\n\"weak confinement\" (close to \"unconfined\"). In horizontal dimensions ($x,y$),\nthe system remains \"unconfined\". Through tracking the tracers dispersed in the\nactive fluids in three dimensions we observed that activity level,\ncharacterized by velocity fluctuations of flow tracers, increases as system\nsize increases. Concomitantly, the velocity-velocity temporal correlation\nchanges from weak correlation to strong positive correlation, indicating\n\"memory\" in active flows. We estimate the characteristic size of the flow\nstructure by integrating the velocity-velocity spatial correlation function.\nThe integral increases as confinement becomes weaker and saturates at\napproximately 400 microns as the system becomes \"unconfined\". This saturation\nindicates an intrinsic length scale which, along with the small-scale isotropy,\ndemonstrates the multi-scale nature of this kinesin-driven bundled microtubule\nsystem."
    },
    {
        "anchor": "Universal consequences of the presence of excluded volume interactions\n  in dilute polymer solutions undergoing shear flow: The role of solvent quality in determining the universal material properties\nof dilute polymer solutions undergoing steady simple shear flow is examined. A\nbead-spring chain representation of the polymer molecule is used, and the\ninfluence of solvent molecules on polymer conformations is modelled by a narrow\nGaussian excluded volume potential that acts pair-wise between the beads of the\nchain. Brownian dynamics simulations data, acquired for chains of finite\nlength, and extrapolated to the limit of infinite chain length, are shown to be\nmodel independent. This feature of the narrow Gaussian potential, which leads\nto results identical to a $\\delta$-function repulsive potential, enables the\nprediction of both universal crossover scaling functions and asymptotic\nbehavior in the excluded volume limit. Universal viscometric functions,\nobtained by this procedure, are found to exhibit increased shear thinning with\nincreasing solvent quality. In the excluded volume limit, they are found to\nobey power law scaling with the characteristic shear rate $\\beta$, in close\nagreement with previously obtained renormalization group results. The presence\nof excluded volume interactions is also shown to lead to a weakening of the\nalignment of the polymer chain with the flow direction.",
        "positive": "Under-knotted and Over-knotted Polymers: Unrestricted Loops: We present computer simulations to examine probability distributions of\ngyration radius for the no-thickness closed polymers of N straight segments of\nequal length. We are particularly interested in the conditional distributions\nwhen the topology of the loop is quenched to be a certain knot, K. The\ndependence of probability distribution on length, N, as well as topological\nstate K are the primary parameters of interest. Our results confirm that the\nmean square average gyration radius for trivial knots scales with N in the same\nway as for self-avoiding walks, where the cross-over length to this\n\"under-knotted\" regime is the same as the characteristic length of random\nknotting, N_0. Probability distributions of gyration radii are somewhat more\nnarrow for topologically restricted under-knotted loops compared to phantom\nloops, meaning knots are entropically more rigid than phantom polymers. We also\nfound evidence that probability distributions approach a universal shape at\nN>N_0 for all simple knots."
    },
    {
        "anchor": "Crystallization in suspensions of hard spheres: A Monte Carlo and\n  Molecular Dynamics simulation study: The crystallization of a metastable melt is one of the most important non\nequilibrium phenomena in condensed matter physics, and hard sphere colloidal\nmodel systems have been used for several decades to investigate this process by\nexperimental observation and computer simulation. Nevertheless, there is still\nan unexplained discrepancy between simulation data and experimental nucleation\nrate densities. In this paper we examine the nucleation process in hard spheres\nusing molecular dynamics and Monte Carlo simulation. We show that the\ncrystallization process is mediated by precursors of low orientational\nbond-order and that our simulation data fairly match the experimental data\nsets.",
        "positive": "Spatial stress correlations in strong colloidal gel: In this work, we systematically investigate for the first time the nature of\nstress correlations in soft colloidal gel materials which support tensile and\ncompressive forces as well as finite rolling torque, as a function of system\npressure. Similar to previous studies on frictional granular matter with only\ncompressive forces and without any rolling torque, the full stress\nautocorrelation matrix is dictated by the pressure and torque autocorrelations\ndue to mechanical balance and material isotropy constraints. Surprisingly, it\nis observed that the gel materials do not behave as a normal elastic solid\nclose to the gel point as assumed loosely in the literature because the real\nspace pressure fluctuations decay slower than the normal. We also demonstrate\nthat at low pressure the fractal like structural correlation determines the\npressure fluctuations and this is manifested in the real space in terms of\ninhomogeneous and anisotropic force networks formed due to large voids. Far\naway from the gel point, as the voids collapse under compression, the force\nchain network becomes homogeneous and isotropic and the pressure fluctuations\nbecome normal leading to normal elastic decay at long range, behaving similar\nto frictionless granular matter and glass. We also observe that the torque\nautocorrelation is not hyperuniform in the presence of rolling resistance close\nto the gel point. Furthermore, we link the abnormal pressure fluctuations to\nthe non-hyperuniform behaviour of the system with respect to the local packing\nfraction fluctuations, thus relating the deviations from the normal elastic\nbehaviour across various non-equilibrium systems under a common framework."
    },
    {
        "anchor": "Selective nucleation in porous media: Geometrical arguments suggest that pore-mediated nucleation happens in\ngeneral in a two-step fashion, the first step being nucleation within the pore,\nthe second being nucleation from the filled pore into solution [Page & Sear,\nPhys. Rev. Lett. 97, 65701 (2006)]. The free energy barriers controlling the\ntwo steps of this process show opposite dependencies on pore size, implying\nthat for given thermodynamic conditions there exists a pore size for which\nnucleation happens fastest. Here we show, within the two- and three-dimensional\nIsing lattice gas, that this preferred pore size tracks the size of the bulk\ncritical nucleus, up to a numerical prefactor. This observation suggests a\nsimple prescription for directing nucleation to certain locations within\nheterogeneous porous media.",
        "positive": "Dynamics of alpha- and beta- processes in thin polymer films: poly(vinyl\n  acetate) and poly(methyl methacrylate): Dynamics of thin films of poly(vinyl acetate) (PVAc) and poly(methyl\nmethacrylate) (PMMA) have been investigated by dielectric relaxation\nspectroscopy in the frequency range from 0.1Hz to 1MHz at temperatures from\n263K to 423K. The $\\alpha$-process, the key process of glass transition, is\nobserved for thin films of PVAc and PMMA as a dielectric loss peak at a\ntemperature $T_{\\alpha}$ in temperature domain with a fixed frequency. For PMMA\nthe $\\beta$-process is also observed at a temperature $T_{\\beta}$. For PVAc,\n$T_{\\alpha}$ decreases gradually with decreasing thickness, and the thickness\ndependence of $T_{\\alpha}$ is almost independent of the molecular weight\n($M_{\\rm w}\\le2.4\\times10^5$). For PMMA, $T_{\\alpha}$ remains almost constant\nas thickness decreases down to a critical thickness $d_c$, at which point it\nbegins to decrease with decreasing thickness. Contrastingly, $T_{\\beta}$\ndecreases gradually as thickness decreases to $d_c$, and below $d_c$ it\ndecreases drastically. For both PVAc and PMMA, the broadening of the\ndistribution of the relaxation times in thinner films is observed and this\nbroadening is more pronounced for the $\\alpha$-process than for the\n$\\beta$-process. It is also observed that the relaxation strength is depressed\nas the thickness decreases for both the polymers."
    },
    {
        "anchor": "Axisymmetric monopole and dipole flow singularities in proximity of a\n  stationary no-slip plate immersed in a Brinkman fluid: Green's function plays an important role in many areas of physical sciences\nand is a prime tool for solving diverse hydrodynamic equations in the linear\nregime. In the present contribution, the axisymmetric low-Reynolds-number\nBrinkman flow induced by monopole and dipole singularities in proximity of a\nstationary plate of circular shape is theoretically investigated. The flow\nsingularities are directed along the central axis of the plate. No-slip\nboundary conditions are assumed to hold at the surface of the plate. The\nGreen's functions are determined to a large extent analytically, reducing the\nsolution of the linear hydrodynamic equations to well-behaved one-dimensional\nintegrals amenable to numerical computation. In our approach, the Brinkman flow\nproblem is formulated as a mixed boundary value problem that is subsequently\nmapped in the form of dual integral equations on the domain boundaries.\nThereupon, the solution of the equations of fluid motion is eventually reduced\nto the solution of two independent Fredholm integral equations of the first\nkind. The overall flow structure and emerging eddy patterns are found to\nstrongly depend on the magnitude of the relevant geometrical and physical\nparameters of the system. Moreover, the effect of the confining plate on the\ndynamics of externally driven or force-free particles is assessed through the\ncalculation of the relevant hydrodynamic reaction functions. The effect of the\nplate on the locomotory behavior of a self-propelling active dipole swimmer is\nshown to be maximum when the radius of the plate is comparable to the distance\nseparating the swimmer from the plate. Our results may prove useful for\ncharacterizing transport processes in microfluidic devices and may pave the way\ntoward understanding and controlling of small-scale flows in porous media.",
        "positive": "Deeper penetration of surface effects on particle mobility than on\n  hopping rate in glassy polymer films: Free surfaces in glassy polymer films are known to induce surface mobile\nlayers with enhanced dynamics. Using molecular dynamics simulations of a\nbead-spring model, we study a wide variety of layer-resolved structural and\ndynamical properties of polymer films equilibrated at a low temperature.\nSurface enhancement on thermally induced particle hopping rate is found to\nterminate abruptly only about 5 particle diameters from the free surface. In\ncontrast, enhancement on the net motions of particles measured at longer time\nscales penetrates at least 2 particle diameters deeper. The diverse penetration\ndepths show the existence of a peculiar sublayer, referred to as the\ninner-surface layer, in which surface enhanced mobility is not caused by more\nfrequent particle hops but instead by a reduced dynamic heterogeneity\nassociated with diminished hopping anti-correlations. Confinement effects of\nthe free surface thus provide a unique mechanism for varying the dynamic\nheterogeneity and hopping correlations while keeping the hopping rate constant.\nOur results highlight the importance of correlations among elementary motions\nto glassy slowdown and suggest that dynamic facilitation is mediated via\nperturbations to the correlations rather than the rate of elementary motions."
    },
    {
        "anchor": "Probing the equilibrium dynamics of colloidal hard spheres above the\n  mode-coupling glass transition: We use dynamic light scattering and computer simulations to study equilibrium\ndynamics and dynamic heterogeneity in concentrated suspensions of colloidal\nhard spheres. Our study covers an unprecedented density range and spans seven\ndecades in structural relaxation time, $\\ta$, including equilibrium easurements\nabove $\\phi_{\\rm c}$, the location of the glass transition deduced from fitting\nour data to mode-coupling theory. Instead of falling out of equilibrium, the\nsystem remains ergodic above $\\phi_{\\rm c}$ and enters a new dynamical regime\nwhere $\\ta$ increases with a functional form that was not anticipated by\nprevious experiments, while the amplitude of dynamic heterogeneity grows slower\nthan a power law with $\\ta$, as found in molecular glass-formers close to the\nglass transition.",
        "positive": "Inertial Effects on Fluid Flow through Disordered Media: We investigate the origin of the deviations from the classical Darcy law by\nnumerical simulation of the Navier-Stokes equations in two-dimensional\ndisordered porous media. We apply the Forchheimer equation as a\nphenomenological model to correlate the variations of the friction factor for\ndifferent porosities and flow conditions. At sufficiently high Reynolds\nnumbers, when inertia becomes relevant, we observe a transition from linear to\nnon-linear behavior which is typical of experiments. We find that such a\ntransition can be understood and statistically characterized in terms of the\nspatial distribution of kinetic energy in the system."
    },
    {
        "anchor": "Filling transition for a wedge: We study the formation and the shape of a liquid meniscus in a wedge with\nopening angle $2\\phi$ which is exposed to a vapor phase. By applying a suitable\neffective interface model, at liquid-vapor coexistence and at a temperature\n$T_{\\phi}$ we find a filling transition at which the height of the meniscus\nbecomes macroscopically large while the planar walls of the wedge far away from\nits center remain nonwet up to the wetting transition occurring at\n$T_w>T_{\\phi}$. Depending on the fluid and the substrate potential the filling\ntransition can be either continuous or discontinuous. In the latter case it is\naccompanied by a prefilling line extending into the vapor phase of the bulk\nphase diagram and describing a transition from a small to a large, but finite,\nmeniscus height. The filling and the prefilling transitions correspond to\nnonanalyticities in the surface and line contributions to the free energy of\nthe fluid, respectively.",
        "positive": "A threshold-force model for adhesion and mode I fracture: We study the relation between a threshold-force based model at the\nmicroscopic scale and mode I fracture at the macroscopic scale in a system of\ndiscrete interacting springs. Specifically, we idealize the contact between two\nsurfaces as that between a rigid surface and a collection of springs with\nlong-range interaction and a constant tensile threshold force. We show that a\nparticular scaling similar to that of crack-tip stress in Linear Elastic\nFracture Mechanics leads to a macroscopic limit behavior. The model also\nreproduces the scaling behaviors of the JKR model of adhesive contact. We\ndetermine how the threshold force depends on the fracture energy and elastic\nproperties of the material. The model can be used to study rough-surface\nadhesion."
    },
    {
        "anchor": "Anisotropic relaxations introduced by Cd impurities in Rutile TiO2:\n  first-principles calculations and experimental support: We present an ab initio study of the relaxations introduced in TiO2 when a Cd\nimpurity substitutes a Ti atom and the experimental test of this calculation by\na perturbed-angular-correlation (PAC) measurement of the orientation of the\nelectric-field gradient (EFG) tensor at the Cd site. The ab-initio calculation\npredicts strong anisotropic relaxations of the nearest oxygen neighbors of the\nimpurity and a change of the orientation of the largest EFG tensor component,\nV33, from the [001] to the [110] direction upon substitution of a Ti atom by a\nCd impurity. The last prediction is confirmed by the PAC experiment that shows\nthat V33 at the Cd site is parallel to either the [110] or the [1\\bar{1}0]\ncrystal axis.",
        "positive": "Friction between Ring Polymer Brushes: Friction between ring-polymer brushes at melt densities sliding past each\nother are studied using extensive course-grained molecular dynamics simulations\nand scaling arguments, and the results are compared to the friction between\nlinear-polymer brushes. We show that for a velocity range spanning over three\ndecades, the frictional forces measured for ring-polymer brushes are half the\ncorresponding friction in case of linear brushes. In the linear-force regime,\nthe weak inter-digitation of two ring brushes compared to linear brushes also\nleads to a lower number of binary collisions between the monomers of opposing\nbrushes. At high velocities, where the thickness of the inter-digitation layer\nbetween two opposing brushes is on the order monomer size regardless of brush\ntopology, stretched segments of ring polymers take a double-stranded\nconformation. As a result, monomers of the double-stranded segments collide\nless with the monomers of the opposing ring brush even though a similar number\nof monomers occupies the inter-digitation layer for ring and linear-brush\nbilayers. The numerical data obtained from our simulations is consistent with\nthe proposed scaling analysis. Conformation-dependent frictional reduction\nobserved in ring brushes can have important consequences in non-equilibrium\nbulk systems."
    },
    {
        "anchor": "Odd elasticity in Hamiltonian formalism: A host of elastic systems consisting of active components exhibit\npath-dependent elastic behaviors not found in classical elasticity, which is\nknown as odd elasticity. Odd elasticity is characterized by antisymmetric (odd)\nelastic modulus tensor. Here, from the perspective of geometry, we construct\nthe Hamiltonian formalism to show the origin of the antisymmetry of the elastic\nmoduli. Furthermore, both non-conservative stress and the associated nonlinear\nconstitutive relation naturally arise. This work also opens the promising\npossibility of exploring the physics of odd elasticity in dynamical regime by\nHamiltonian formalism.",
        "positive": "Texture transitions in the liquid crystalline alkyloxybenzoic acid 6OBAC: The 4,n-alkyloxybenzoic acid 6OBAC has a very rich variety of crystalline\nstructures and two nematic sub-phases, characterised by different textures. It\nis a material belonging to a family of liquid crystals formed by hydrogen\nbonded molecules, the 4,n-alkyloxybenzoic acids indicates the homologue\nnumber). The homologues with n ranging from 7 to 13 display both smectic C and\nN phases. In spite of the absence of a smectic phase, 6OBAC exhibits two\nsub-phases with different textures, as it happens in other materials of the\nhomologue series which possess the smectic phase. This is the first material\nthat exhibits a texture transition in a nematic phase directly originated from\na crystal phase. Here we present the results of an image processing assisted\noptical investigation to characterise the textures and the transitions between\ntextures. This processing is necessary to discriminate between crystal\nmodifications and nematic sub-phases."
    },
    {
        "anchor": "Linear instability of shear thinning pressure driven channel flow: We study theoretically pressure driven planar channel flow of shear thinning\nviscoelastic fluids. Combining linear stability analysis and full nonlinear\nsimulation, we study the instability of an initially one-dimensional base state\nto the growth of two-dimensional perturbations with wavevector in the flow\ndirection. We do so within three widely used constitutive models: the\nmicroscopically motivated Rolie-Poly model, and the phenomenological\nJohnson-Segalman and White-Metzner models. In each model, we find instability\nwhen the degree of shear thinning exceeds some level characterised by the\nlogarithmic slope of the flow curve at its shallowest point. Specifically, we\nfind instability for $n<n^*$, with $n^*\\approx 0.21, 0.11$ and $0.30$ in the\nRolie-Poly, Johnson-Segalman and White-Metzner models respectively. Within each\nmodel, we show that the critical pressure drop for the onset of instability\nobeys a criterion expressed in terms of this degree of shear thinning, $n$,\ntogether with the derivative of the first normal stress with respect to shear\nstress. Both shear thinning and rapid variations in first normal stress across\nthe channel are therefore key ingredients driving the instability. In the\nRolie-Poly and Johnson-Segalman models, the underlying mechanism appears to\ninvolve the destabilisation of a quasi-interface that exists in each half of\nthe channel, across which the normal stress varies rapidly. In the\nWhite-Metzner model, no such quasi-interface exists, but the criterion for\ninstability nonetheless appears to follow the same form as in the Rolie-Poly\nand Johnson-Segalman models. This presents an outstanding puzzle concerning any\npossibly generic nature of the instability mechanism. We finally make some\nbriefly comments on the Giesekus model, which is rather different in its\npredictions from the other three.",
        "positive": "Drying of agarose gels monitored by in-situ interferometry: Hydrogels behave as viscoelastic soft solids and display a porous\nmicrostructure filled with water with typical amounts of 90\\%~w/w or more. As\nsuch, these materials are highly sensitive to water loss through evaporation,\nwhich impacts their mechanical properties. Yet, aside from scattered empirical\nobservations, little is known about the gel drying kinetics for which there is\na lack of temporally and spatially resolved measurements. Here we report a\nbenchmark study of the slow drying of agarose gels cast in cylindrical Petri\ndishes. The weak adhesion of the gel to the lateral wall of the dish guarantees\nthat the gel diameter remains constant during the drying process and that the\ngel shrinkage is purely vertical. The thinning rate is monitored by in-situ\ninterferometry using a Michelson interferometer. The displacement of\ninterference fringes are analyzed using an original spatiotemporal filtering\nmethod, which allows us to measure local thinning rates of about 10~nm/s with\nhigh accuracy. Experiments conducted at different positions along the gel\nradius show that the gel thins locally with a constant velocity before\nexperiencing a sudden collapse at the end of the drying process. We further use\nthe thinning rate measured at the center of the dish during the early stage of\nthe drying process as a robust observable to quantify the role of additives on\nthe gel drying kinetics and compare gels of different compositions. Our work\nexemplifies interferometry as a powerful tool to quantify the impact of minute\namounts of additives on the drying of biopolymer gels."
    },
    {
        "anchor": "Finite temperature mechanical instability in disordered lattices: Mechanical instability takes different forms in various ordered and\ndisordered systems. We study the effect of thermal fluctuations in two\ndisordered central-force lattice models near mechanical instability: randomly\ndiluted triangular lattice and randomly braced square lattice. These two\nlattices exhibit different scalings for the emergence of rigidity at $T=0$ due\nto their different patterns of self stress at the transition. Using analytic\ntheory we show that thermal fluctuations stabilize both lattices. In\nparticular, the triangular lattice displays a critical regime in which the\nshear modulus scales as $G \\sim T^{1/2}$, whereas the square lattice shows $G\n\\sim T^{2/3}$.",
        "positive": "Molecular Dynamics Simulation Study of Interaction between Model Rough\n  Hydrophobic Surfaces: We study some aspects of hydrophobic interaction between molecular rough and\nflexible model surfaces. The model we use in this work is based on a model we\nused previously (Eun, C.; Berkowitz, M. L. J. Phys. Chem. B 2009, 113,\n13222-13228), when we studied the interaction between model patches of lipid\nmembranes. Our original model consisted of two graphene plates with attached\npolar headgroups; the plates were immersed in a water bath. The interaction\nbetween such plates can be considered as an example of a hydrophilic\ninteraction. In the present work we modify our previous model by removing the\ncharge from the zwitterionic headgroups. As a result of this procedure, the\nplate character changes; it becomes hydrophobic. By separating the total\ninteraction (or potential of mean force, PMF) between plates into the direct\nand the water-mediated interactions we observe that the latter changes from\nrepulsive to attractive, clearly emphasizing the important role of water as a\nmedium. We also investigate the effect of roughness and flexibility of the\nheadgroups on the interaction between plates and observe that roughness\nenhances the character of the hydrophobic interaction. The presence of a\ndewetting transition in a confined space between charge-removed plates confirms\nthat the interaction between plates is strongly hydrophobic. In addition, we\nnotice that there is a shallow local minimum in the PMF in case of\ncharge-removed plates. We find that this minimum is associated with the\nconfigurational changes that flexible headgroups undergo, as the two plates are\nbrought together."
    },
    {
        "anchor": "Taylor-like vortices in the shear-banding flow of giant micelles: Using flow visualizations in Couette geometry, we demonstrate the existence\nof Taylor-like vortices in the shear-banding flow of a giant micelles system.\nWe show that vortices stacked along the vorticity direction develop\nconcomitantly with interfacial undulations. These cellular structures are\nmainly localized in the induced band and their dynamics is fully correlated\nwith that of the interface. As the control parameter increases, we observe a\ntransition from a steady vortex flow to a state where pairs of vortices are\ncontinuously created and destroyed. Normal stress effects are discussed as\npotential mechanisms driving the three-dimensional flow.",
        "positive": "Critical scaling and aging in cooling systems near the jamming\n  transition: We conduct athermal simulations of freely-cooling, viscous soft spheres\naround the jamming transition density \\phi_{J}, and find evidence for a growing\nlength \\xi(t) that governs relaxation to mechanical equilibrium. \\xi(t) is\nmanifest in both the velocity correlation function, and the spatial\ncorrelations in a scalar measure of local force balance which we define. Data\nfor different densities \\phi can be collapsed onto two master curves by scaling\n\\xi(t) and t by powers of |\\phi-\\phi_{J}|, indicative of critical scaling.\nFurthermore, particle transport for \\phi>\\phi_{J} exhibits aging and\nsuperdiffusion similar to a range of soft matter experiments, suggesting a\ncommon origin. Finally, we explain how \\xi(t) at late times maps onto known\nbehavior away from \\phi_{J}."
    },
    {
        "anchor": "Fluctuations and scaling of inverse participation ratios in random\n  binary resonant composites: We study the statistics of local field distribution solved by the\nGreen's-function formalism (GFF) [Y. Gu et al., Phys. Rev. B {\\bf 59} 12847\n(1999)] in the disordered binary resonant composites. For a percolating\nnetwork, the inverse participation ratios (IPR) with $q=2$ are illustrated, as\nwell as the typical local field distributions of localized and extended states.\nNumerical calculations indicate that for a definite fraction $p $ the\ndistribution function of IPR $P_q$ has a scale invariant form. It is also shown\nthe scaling behavior of the ensemble averaged $<P_{q}>$ described by the\nfractal dimension $D_q$. To relate the eigenvectors correlations to resonance\nlevel statistics, the axial symmetry between $D_2$ and the spectral\ncompressibility $\\chi$ is obtained.",
        "positive": "Similarity solutions in elastohydrodynamic bouncing: We investigate theoretically and numerically the impact of an elastic sphere\non a rigid wall in a viscous fluid. Our focus is on the dynamics of the\ncontact, employing the soft lubrication model in which the sphere is separated\nfrom the wall by a thin liquid film. In the limit of large sphere inertia, the\nsphere bounces and the dynamics is close to the Hertz theory. Remarkably, the\nfilm thickness separating the sphere from the wall exhibits non-trivial\nself-similar properties that vary during the spreading and retraction phases.\nLeveraging these self-similar properties, we establish the energy budget and\npredict the coefficient of restitution for the sphere. The general framework\nderived here opens many perspectives to study the lubrication film in impact\nproblems."
    },
    {
        "anchor": "Polar coordinate lattice Boltzmann kinetic modeling of detonation\n  phenomena: A novel polar coordinate lattice Boltzmann kinetic model for detonation\nphenomena is presented and applied to investigate typical implosion and\nexplosion processes. In this model, the change of discrete distribution\nfunction due to local chemical reaction is dynamically coupled into in the\nmodified lattice Boltzmann equation, which could recovery the Navier-Stokes\nequations, including contribution of chemical reaction, via the Chapman-Enskog\nexpansion. For the numerical investigations, the main focuses are the\nnonequilibrium behaviors in these processes. The system at the disc center is\nalways in its thermodynamic equilibrium. The internal kinetic energies in\ndifferent degrees freedoms around the detonation front do not coincide due to\nthe fluid viscosity. They show the maximum difference at the inflexion point\nwhere the pressure has the largest spatial derivative. The dependence of the\nreaction rate on the pressure, influences of the shock strength and reaction\nrate on the departure amplitude of the system from its local thermodynamic\nequilibrium are probed.",
        "positive": "On the phase diagram of Mackay icosahedra: Using Monte Carlo and molecular dynamics simulations, we investigate the\nequilibrium phase behavior of a monodisperse system of Mackay icosahedra. We\ndefine the icosahedra as polyatomic molecules composed of a set of\nLennard-Jones subparticles arranged on the surface of the Mackay icosahedron.\nThe phase diagram contains a fluid phase, a crystalline phase and a rotator\nphase. We find that the attractive icosahedral molecules behave similar to hard\ngeometric icosahedra for which the densest lattice packing and the rotator\ncrystal phase have been identified before. We show that both phases form under\nattractive interactions as well. When heating the system from the dense crystal\npacking, there is first a transition to the rotator crystal and then another to\na fluid phase."
    },
    {
        "anchor": "Thermodynamics and structure of self-assembled networks: We study a generic model of self-assembling chains which can branch and form\nnetworks with branching points (junctions) of arbitrary functionality. The\nphysical realizations include physical gels, wormlike micells, dipolar fluids\nand microemulsions. The model maps the partition function of a solution of\nbranched, self-assembling, mutually avoiding clusters onto that of a Heisenberg\nmagnet in the mathematical limit of zero spin components. The model is solved\nin the mean field approximation. It is found that despite the absence of any\nspecific interaction between the chains, the entropy of the junctions induces\nan effective attraction between the monomers, which in the case of three-fold\njunctions leads to a first order reentrant phase separation between a dilute\nphase consisting mainly of single chains, and a dense network, or two network\nphases. Independent of the phase separation, we predict the percolation\n(connectivity) transition at which an infinite network is formed that partially\noverlaps with the first-order transition. The percolation transition is a\ncontinuous, non thermodynamic transition that describes a change in the\ntopology of the system. Our treatment which predicts both the thermodynamic\nphase equilibria as well as the spatial correlations in the system allows us to\ntreat both the phase separation and the percolation threshold within the same\nframework. The density-density correlation correlation has a usual\nOrnstein-Zernicke form at low monomer densities. At higher densities, a peak\nemerges in the structure factor, signifying an onset of medium-range order in\nthe system. Implications of the results for different physical systems are\ndiscussed.",
        "positive": "NVU dynamics. III. Simulating molecules at constant potential energy: This is the final paper in a series that introduces geodesic molecular\ndynamics at constant potential energy. This dynamics is entitled NVU dynamics\nin analogy to standard energy-conserving Newtonian NVE dynamics. In the first\ntwo papers [Ingebrigtsen et al., J. Chem. Phys. 135, 104101 (2011); ibid,\n104102 (2011)], a numerical algorithm for simulating geodesic motion of atomic\nsystems was developed and tested against standard algorithms. The conclusion\nwas that the NVU algorithm has the same desirable properties as the Verlet\nalgorithm for Newtonian NVE dynamics, i.e., it is time-reversible and\nsymplectic. Additionally, it was concluded that NVU dynamics becomes equivalent\nto NVE dynamics in the thermodynamic limit. In this paper, the NVU algorithm\nfor atomic systems is extended to be able to simulate geodesic motion of\nmolecules at constant potential energy. We derive an algorithm for simulating\nrigid bonds and test this algorithm on three different systems: an asymmetric\ndumbbell model, Lewis-Wahnstrom OTP, and rigid SPC/E water. The rigid bonds\nintroduce additional constraints beyond that of constant potential energy for\natomic systems. The rigid-bond NVU algorithm conserves potential energy, bond\nlengths, and step length for indefinitely long runs. The quantities probed in\nsimulations give results identical to those of Nose-Hoover NVT dynamics. Since\nNose-Hoover NVT dynamics is known to give results equivalent to those of NVE\ndynamics, the latter results show that NVU dynamics becomes equivalent to NVE\ndynamics in the thermodynamic limit also for molecular systems."
    },
    {
        "anchor": "Like-charge attraction in confinement: myth or truth ?: It is general wisdom that likely charged colloidal particles repel each other\nwhen suspended in liquids. This is in perfect agreement with mean field\ntheories being developed more than 60 years ago. Accordingly, it was a big\nsurprise when several groups independently reported long-ranged attractive\ncomponents in the pair potential U(r) of equally charged colloids. This\nso-called like-charge attraction (LCA) was only observed in thin sample cells\nwhile the pair-interaction in unconfined suspensions has been experimentally\nconfirmed to be entirely repulsive. Despite considerable experimental and\ntheoretical efforts, LCA remains one of the most challenging mysteries in\ncolloidal science. We experimentally reinvestigate the pair-potential U(r) of\ncharged colloidal particles with digital video microscopy and demonstrate that\noptical distortions in the particles images lead to slightly erroneous particle\npositions. If not properly taken into account, this artefact pretends a minimum\nin U(r) which was in the past misleadingly interpreted as LCA. After correcting\noptical distortions we obtain entirely repulsive pair interactions which show\ngood agreement with linearized mean field theories.",
        "positive": "Emergence of Rigidity Percolation in Flowing Granular Systems: Jammed granular media and glasses exhibit spatial long-range correlations as\na result of mechanical equilibrium. However, the existence of such correlations\nin the flowing matter, where the mechanical equilibrium is unattainable, has\nremained elusive. Here, we investigate this problem in the context of the\npercolation of interparticle forces in flowing granular media. We find that the\nflow rate introduces an effective long-range correlation, which plays the role\nof a relevant perturbation giving rise to a spectrum of varying exponents on a\ncritical line as a function of the flow rate. Remarkably, our numerical\nsimulations along with analytical arguments predict a crossover flow rate\n$\\dot{\\gamma}_c \\simeq 10^{-5}$ below which the effect of induced disorder is\nweak and the universality of the force chain structure is shown to be given by\nthe standard rigidity percolation. We also find a power-law behavior for the\ncritical exponents with the flow rate $\\dot{\\gamma}>\\dot{\\gamma}_c$."
    },
    {
        "anchor": "Adaptive Speckle Imaging Interferometry: a new technique for the\n  analysis of microstructure dynamics, drying processes and coating formation: We describe an extension of multi-speckle diffusing wave spectroscopy adapted\nto follow the non-stationary microscopic dynamics in drying films and coatings\nin a very reactive way and with a high dynamic range. We call this technique\n\"Adaptive Speckle Imaging Interferometry\". We introduce an efficient tool, the\ninter-image distance, to evaluate the speckle dynamics, and the concept of\n\"speckle rate\" (SR, in Hz) to quantify this dynamics. The adaptive algorithm\nplots a simple kinetics, the time evolution of the SR, providing a non-invasive\ncharacterization of drying phenomena. A new commercial instrument, called\nHORUS(R), based on ASII and specialized in the analysis of film formation and\ndrying processes is presented.",
        "positive": "Adaptable DNA interactions regulate surface triggered self assembly: DNA-mediated multivalent interactions between colloidal particles have been\nextensively applied for their ability to program bulk phase behaviour and\ndynamic processes. Exploiting the competition between different types of\nDNA-DNA bonds, here we experimentally demonstrate the selective triggering of\ncolloidal self-assembly in the presence of a functionalised surface, which\ninduces changes in particle-particle interactions. Besides its relevance to the\nmanufacturing of layered materials with controlled thickness, the intrinsic\nsignal-amplification features of the proposed interaction scheme make it\nvaluable for biosensing applications."
    },
    {
        "anchor": "Controlling the temperature sensitivity of DNA-mediated colloidal\n  interactions through competing linkages: We propose a new strategy to improve the self-assembly properties of\nDNA-functionalised colloids. The problem that we address is that\nDNA-functionalised colloids typically crystallize in a narrow temperature\nwindow, if at all. The underlying reason is the extreme sensitivity of\nDNA-mediated interactions to temperature or other physical control parameters.\nWe propose to widen the window for colloidal crystallization by exploiting the\ncompetition between DNA linkages with different nucleotide sequences, which\nresults in a temperature-dependent switching of the dominant bond type.\nFollowing such a strategy, we can decrease the temperature dependence of\nDNA-mediated self assembly to make systems that can crystallize in a wider\ntemperature window than is possible with existing systems of DNA functionalised\ncolloids. We report Monte Carlo simulations that show that the proposed\nstrategy can indeed work in practice for real systems and specific, designable\nDNA sequences. Depending on the length ratio of the different DNA constructs,\nwe find that the bond switching is either energetically driven (equal length or\n`symmetric' DNA) or controlled by a combinatorial entropy gain (`asymmetric'\nDNA), which results from the large number of possible binding partners for each\nDNA strand. We provide specific suggestions for the DNA sequences with which\nthese effects can be achieved experimentally.",
        "positive": "New scaling paradigm for dynamics in glass-forming systems: The lack of ultimate scaling relations for previtreous changes of the primary\nrelaxation time or viscosity in glass-forming systems constitutes the grand\nfundamental challenge, also hindering the development of relevant material\nengineering applications. The report links the problem to the location of the\nprevitreous domain remote from a hypothetical singularity. As the solution, the\nlinearized, distortions-sensitive analysis is proposed. It is developed for\nscaling-relations linked to basic glass transition models: free volume,\nentropic, critical-like, avoided criticality, and kinetically constrained\napproaches. For all model scaling relations their alternative formulations\nbased on fragility, the semi-universal metric of dynamics, are presented. The\ndistortions-sensitive analysis is supplemented by the alternative approach\nbased on the activation energy index showing its relative changes on cooling in\nthe previtreous region. The search for the coherent description of the\nprevitreous dynamics in the homologous series of polyols, from glycerol to\nsorbitol, is used to present in practice and validate the application of the\ndistortions sensitive analysis. Only two scaling equation, MYEGA and the recent\n'activation and critical' (AC), passed such exam. They also revealed a limited\nreliability of the Stickel operator' analysis for detecting the dynamic\ncrossover. The report constitutes the unique tool-guide for applications, and a\ncheckpoint analysis of the glass transition models. The discussion focuses on\nthe temperature path on cooling but the extension for the still hardly\ndiscussed pressure path is also discussed."
    },
    {
        "anchor": "Conformational Transition of H-shaped Branched Polymers: We report dynamic Monte Carlo simulation on conformational transition of\nH-shaped branched polymers by varying main chain (backbone) and side chain\n(branch) length. H-shaped polymers in comparison with equivalent linear\npolymers exhibit a depression of theta temperature accompanying with smaller\nchain dimensions. We observed that the effect of branches on backbone dimension\nis more pronounced than the reverse, and is attributed to the conformational\nheterogeneity prevails within the molecule. With increase in branch length,\nbackbone is slightly stretched out in coil and globule state. However, in the\npre-collapsed (cf. crumpled globule) state, backbone size decreases with the\nincrease of branch length. We attribute this non-monotonic behavior as the\ninterplay between excluded volume interaction and intra-chain bead-bead\nattractive interaction during collapse transition. Structural analysis reveals\nthat the inherent conformational heterogeneity promotes the formation of a\ncollapsed structure with segregated backbone and branch units (resembles to\n'sandwich' or 'Janus' morphology) rather an evenly distributed structure\ncomprising of all the units. The shape of the collapsed globule becomes more\nspherical with increasing either backbone or branch length.",
        "positive": "The bending of an elastic beam by a liquid drop: A variational approach: We study the interaction of a liquid drop with an elastic beam in the case\nwhere bending effects dominate. We use a variational approach to derive\nequilibrium equations for the system in the presence of gravity and in the\npresence or absence of contact line pinning. We show that the derived\nequilibrium equations for the beam subsystem reveal the external forces applied\non the beam by the liquid and vapor phases. Among these, the force applied at\nthe triple line (the curve where the three phases meet) is found to lie along\nthe liquid-vapor interface."
    },
    {
        "anchor": "Direct evidence of void induced structural relaxations in colloidal\n  glass formers: Particle dynamics in supercooled liquids are often dominated by string-like\nmotions in which lines of particles perform activated hops cooperatively. The\nstructural features triggering these motions, crucial in understanding glassy\ndynamics, remain highly controversial. We experimentally study microscopic\nparticle dynamics in colloidal glass formers at high packing fractions. With a\nsmall polydispersity leading to glass-crystal coexistence, a void in the form\nof a vacancy in the crystal can diffuse reversibly into the glass and further\ninduces string-like motions. In the glass, a void takes the form of a\nquasi-void consisting of a few neighboring free volumes and is transported by\nthe string-like motions it induces. In fully glassy systems with a large\npolydispersity, similar quasi-void actions are observed. The mobile particles\ncluster into string-like or compact geometries, but the compact ones can\nfurther be broken down into connected sequences of strings, establishing their\ngeneral importance.",
        "positive": "Stress transmission in granular matter: The transmission of forces through a disordered granular system is studied by\nmeans of a geometrical-topological approach that reduces the granular packing\ninto a set of layers. This layered structure constitutes the skeleton through\nwhich the force chains set up. Given the granular packing, and the region where\nthe force is applied, such a skeleton is uniquely defined. Within this\nframework, we write an equation for the transmission of the vertical forces\nthat can be solved recursively layer by layer. We find that a special class of\nanalytical solutions for this equation are L\\'evi-stable distributions. We\ndiscuss the link between criticality and fragility and we show how the\ndisordered packing naturally induces the formation of force-chains and arches.\nWe point out that critical regimes, with power law distributions, are\nassociated with the roughness of the topological layers. Whereas, fragility is\nassociated with local changes in the force network induced by local granular\nrearrangements or by changes in the applied force. The results are compared\nwith recent experimental observations in particulate matter and with computer\nsimulations."
    },
    {
        "anchor": "Inverse Design of Multicomponent Assemblies: Inverse design can be a useful strategy for discovering interactions that\ndrive particles to spontaneously self-assemble into a desired structure. Here,\nwe extend an inverse design methodology--relative entropy optimization--to\ndetermine isotropic interactions that promote assembly of targeted\nmulticomponent phases, and we apply this extension to design interactions for a\nvariety of binary crystals ranging from compact triangular and square\narchitectures to highly open structures with dodecagonal and octadecagonal\nmotifs. We compare the resulting optimized (self and cross) interactions for\nthe binary assemblies to those obtained from optimization of analogous\nsingle-component systems. This comparison reveals that self interactions act as\na `primer' to position particles at approximately correct coordination shell\ndistances, while cross interactions act as the `binder' that refines and locks\nthe system into the desired configuration. For simpler binary targets, it is\npossible to successfully design self-assembling systems while restricting one\nof these interaction types to be a hard-core-like. However, optimization of\nboth self and cross interaction types appears necessary to design for assembly\nof more complex or open structures.",
        "positive": "Diffusion and interaction effects on molecular release from collapsed\n  microgels: The transport of biomolecules, drugs, or reactants encapsulated inside\nstimuli-responsive polymer networks in aqueous media is fundamental for many\nmaterial and environmental science applications, including drug delivery,\nbiosensing, catalysis, nanofiltration, water purification, and desalination.\nThe transport is particularly complex in dense polymer media, such as collapsed\nhydrogels, where the molecules strongly interact with the polymer network and\ndiffuse via a hopping mechanism. In this study, we employ Dynamical Density\nFunctional Theory (DDFT) to investigate the non-equilibrium release kinetics of\nnon-ionic subnanometer-sized molecules initially uploaded inside collapsed\nmicrogel particles. The theory is consistent with previous molecular dynamics\nsimulations of collapsed poly($N$-isopropylacrylamide) (PNIPAM) polymer\nmatrices, accommodating molecules of varying shapes and sizes. We found that,\ndespite the intricate physico-chemical properties involved in the released\nprocess, the kinetics is predominantly dictated by two material parameters: the\ndiffusion coefficient of the molecules inside the microgel ($D^*$) and the\ninteraction free energy of the molecules with the microgel ($\\Delta G$). Our\nresults reveal two distinct limiting regimes: For large, slowly diffusing\nmolecules weakly attracted to the polymer network, the release is primarily\ndriven by diffusion, with a release time that scales as $\\tau_{1/2} \\sim\n1/D^*$. Conversely, for small molecules strongly attracted to the polymer\nnetwork, the release time is dominated by the interaction, scaling as\n$\\tau_{1/2} \\sim \\exp(-\\Delta G/k_{\\textrm{B}} T)$. Our DDFT calculations are\ndirectly compared with an analytical equation for the half-release time,\ndemonstrating excellent quantitative agreement. This equation represents a\nvaluable tool for predicting release kinetics of non-ionic molecules from\ncollapsed microgels."
    },
    {
        "anchor": "Enhancement of coil-stretch hysteresis by self-concentration in polymer\n  solutions: The effect of concentration on coil-stretch hysteresis in extensional flows\nof polymer solutions is examined with insights from Brownian dynamics\nsimulations of isolated chains and scaling theory for non-dilute solutions. In\nthe hysteresis regime, stretched molecules pervade larger volumes than\nequilibrium coils. For such chains, intermolecular overlap and hydrodynamic\nscreening crossover set in at concentrations much smaller than the critical\noverlap concentration $c^\\ast$ for equilibrium coils. The width of the\nhysteresis window is consequently strongly enhanced around $c^\\ast$.",
        "positive": "Heterogeneous structure of granular aggregates with capillary\n  interactions: We investigate the spatial structure of cohesive granular matter with spheres\nfloating at an air-liquid interface that form disordered close packings with\npores in between. The interface is slowly lowered in a conical container to\nuniformly compress and study the system as a function of area fraction $\\phi$.\nWe find that the free area distributions associated with Voronoi cells show\nsignificant exponential tails indicating greater heterogeneity compared with\nrandom distributions at low $\\phi$ with a crossover towards a\n$\\Gamma$-distribution as $\\phi$ is increased. Further, we find significant\nshort range order as measured by the radial correlation function and the\norientational order parameter even at low and intermediate $\\phi$, which is\nabsent when particles interact only sterically."
    },
    {
        "anchor": "Coordinated Stress-Structure Self-Organization in Granular Packing: It is accepted that stress and structure self-organize cooperatively during\nquasi-static dynamics of granular systems, but the consequences of this\nself-organization are not fully understood. Such an understanding is essential\nbecause local structural properties of the settled material are then correlated\nwith the local stress, which calls into question existing linear theories of\nstress transmission in granular media. A method to quantify the local\nstress-structure correlations is necessary for addressing this issue and we\npresent here such a method for planar systems. We then use it to analyze\nnumerically several different systems, compressed quasi-statically by two\ndifferent procedures. We define cells, cell orders, cell orientations, and cell\nstresses and report the following. 1. The mean ratio of cell principal stresses\ndecreases with cell order and increases with friction. 2. The ratio\ndistributions collapse onto a single curve under a simple scaling, for all\npacking protocols and friction coefficients. 3. Cells orient along the local\nstress major principal axes. 4. A simple first-principles model explains the\ncorrelations between the local cell and stress principal axis orientations. Our\nresults quantify the cooperative stress-structure self-organization and provide\na way to relate quantitatively the stress-structure coupling to different\nprocess parameters and particle characteristics. Significantly, the strong\nstress-structure correlation, driven by structural re-organization upon\napplication of external stress, suggests that current stress theories of\ngranular matter need to be revisited.",
        "positive": "Low density fragile states in cohesive powders: We discuss the difference between cohesive and non-cohesive granular media in\nthe context of a recent report of \"dry quicksand.\" Weak low density states with\nproperties like dry quicksand are readily formed in common household powders.\nIn contrast, such states cannot be formed in cohesionless granular media such\nas ordinary sand."
    },
    {
        "anchor": "Orientational and Translational Hopping in Supercooled Liquids and\n  Glasses : Correlated Dynamics in a Free Energy Landscape: Orientational relaxation (OR) in a viscous, glassy liquid is investigated by\ncarrying out extensive NPT molecular dynamics simulations of isolated\nellipsoids in a glass forming binary mixture.\n  Near the glass transition, the OR occurs mainly via hopping involving either\na ring- or a tunnel like motion, with the participation of several neighboring\natoms. In the glassy state, hopping is found to be accompanied by larger\nfluctuations in the total energy and the volume of the system. Both\norientational and translational hopping are found to be {\\it gated}, restricted\nprimarily by the entropic bottlenecks, with orientation becoming increasingly\nslower than translation as the pressure is increased. OR is heterogeneous, with\na wide distribution of decay times.",
        "positive": "Fluctuation-induced hydrodynamic coupling in an asymmetric, anisotropic\n  dumbbell: We recently introduced a model of an asymmetric dumbbell made of two\nhydrodynamically coupled subunits as a minimal model for a macromolecular\ncomplex, in order to explain the observation of enhanced diffusion of\ncatalytically active enzymes. It was shown that internal fluctuations lead to\nnegative contributions to the overall diffusion coefficient and that the\nfluctuation-induced contributions are controlled by the strength of the\ninteractions between the subunits and their asymmetry. We develop the theory\nfurther by studying the effect of anisotropy of the constituents on the\ndiffusion properties of a modular structure. We derive an analytic form for the\ndiffusion coefficient of an asymmetric, anisotropic dumbbell and show\nsystematically its dependence on the internal and external symmetry. We give\nexpressions for the associated polarisation fields, and comment on their\nconsequences for the alignment mechanism of the dumbbell. The present work\nopens the way to more detailed descriptions of the effect of hydrodynamic\ninteractions on the diffusion and transport properties of biomolecules with\ncomplex structures."
    },
    {
        "anchor": "Capillary-like Fluctuations of a Solid-Liquid Interface in a\n  Non-Cohesive Granular System: One of the most noticeable collective motion of non-cohesive granular matter\nis clustering under certain conditions. In particular, when a\nquasi-two-dimensional monolayer of mono-disperse non-cohesive particles is\nvertically vibrated, a solid-liquid-like transition occurs when the driving\namplitude exceeds a critical value. Here, the physical mechanism underlying\nparticle clustering relies on the strong interactions mediated by grain\ncollisions, rather than on grain-grain cohesive forces. In average, the solid\ncluster resembles a drop, with a striking circular shape. We experimentally\ninvestigate the coarse-grained solid-liquid interface fluctuations, which are\ncharacterized through the static and dynamic correlation functions in the\nFourier space. These fluctuations turn out to be well described by the\ncapillary wave theory, which allows us to measure the solid-liquid interface\nsurface tension and mobility once the granular \"thermal\" kinetic energy is\ndetermined. Despite the system is strongly out of equilibrium and that the\ngranular temperature is not uniform, there is energy equipartition at the\nsolid-liquid interface, for a relatively large range of angular wave-numbers.\nFurthermore, both surface tension and mobility are consistent with a simple\norder of magnitude estimation considering the characteristic energy, length and\ntime scales, which is very similar to what can be done for atomic systems.\n  Please find the supplementary material of this article here: arXiv:1304.2646",
        "positive": "Spontaneous Charge Oscillations in Dielectric Confined Quasi-2D Systems: We report spontaneous electric field and charge oscillations in dielectric\nconfined Quasi-2D charged systems. A simple relationship is found for the\noscillation wave number, which is solely determined by the dielectric mismatch\nand the length scale of confinement. We analytically show that the emergence of\ncharge/field oscillation is due to the arising of a first-order pole in the\nquasi-2D Green's function. The oscillatory behavior is further validated\nnumerically, and its influence on collective behaviors of the confined\nparticles is studied via computer simulations. Interestingly, the substrate\npermittivity alone can trigger spontaneous formations of lattice structures,\nwhich may provide new insights in the study of Quasi-2D systems and the design\nof future nanodevices."
    },
    {
        "anchor": "Acoustic resonance in periodically sheared glass: Using molecular dynamics simulation, we study acoustic resonance in\nlow-temperature glass by applying a small periodic shear at a boundary wall.\nShear wave resonance occurs as the frequency $\\omega$ approaches $\\omega_\\ell=\n\\pi c_\\perp\\ell/L$ ($\\ell=1, 2, 3,...)$. Here, $c_\\perp$ is the transverse\nsound speed and $L$ is the cell length. At resonance, large-amplitude sound\nwaves appear after many cycles even for very small applied strains. They then\ninduce plastic events, which are heterogeneous in space and intermittent on\ntime scales longer than the oscillation period $2\\pi/\\omega$. From these\nirreversible particle motions, there arises strong dissipation suppressing the\ngrowth of sounds. After many resonant cycles, we observe a phenomenon of forced\naging, where the shear modulus (measured after switching off the oscillation)\nis increased significantly.Sometimes, exceptionally large plastic events and\nsystem-size sliding motions induce a transition from resonant to off-resonant\nstates. At resonance, translational diffusion becomes appreciable as well as\naging due to enhanced configurational changes.",
        "positive": "Influence of Shape on Heteroaggregation of Model Microplastics: A\n  Simulation Study: Nano- and microplastics are a growing threat for the environment, especially\nin aqueous habitats. For assessing the influence on the ecosystem and possible\nsolution strategies, it is necessary to investigate the fate of microplastics\n(MP) in the environment. MPs are typically surrounded by natural organic\nmatter, which can cause them to aggregate. However, the effect of MP shape and\nflow conditions on this heteroaggregation is not well understood. To address\nthis gap, we perform simulations of heteroaggregation of different MP shapes\nwith smaller spherical organic matter. We demonstrate that the shape had a\nstrong impact on the aggregate structure. MPs with mostly smooth surfaces\nformed compact structures with a large number of neighbors with weak connection\nstrength and a higher fractal dimension. MPs with edges and corners aggregated\ninto more fractal structures with fewer neighbors, but with stronger\nconnections. Using MPCD, we investigated aggregates under shear flow. The\ncritical shear rate at which the aggregates break up is much larger for\nspherical and rounded cube MPs, i.e, the compact aggregate structure of spheres\noutweighs their weaker connection strength. Most notably, the rounded cube\nexhibited unexpectedly high resistance against breakup under shear. We\nattribute this to being fairly compact due to weaker, flexible neighbor\nconnections, which are still strong enough to prevent particles to break off\nduring shear flow. Irrespective of the stronger connections between\nneighbouring MPs, the fractal aggregates of cubes break up at lower shear\nrates. We find that cube aggregates reduced their radius of gyration\nsignificantly, indicating restructuring, while most neighbor connections were\nkept intact. Aggregates of spheres, however, kept their overall size while\nundergoing local rearrangements, that broke a significant portion of their\nneighbor interactions."
    },
    {
        "anchor": "The G\u014dMartini approach: Revisiting the concept of contact maps and the\n  modelling of protein complexes: We present a review of a series of contact maps for the determination of\nnative interactions in proteins and nucleic acids based on a\ndistance-threshold. Such contact maps are mostly based on physical and chemical\nconstruction, and yet they are sensitive to some parameters (e.g. distances or\natomic radii) and can neglect some key interactions. Furthermore, we also\ncomment on a new class of contact maps that only requires geometric arguments.\nThe contact map is a necessary ingredient to build a robust G\\=oMartini model\nfor proteins and their complexes in the Martini 3 force field. We present the\nextension of a popular structure-based G\\=o-like approach for the study of\nprotein-sugar complexes, and also limitations of this approach are discussed.\nThe G\\=oMartini approach was first introduced by Poma et al. J. Chem. Theory\nComput. 2017, 13(3), 1366-1374 in Martini 2 force field and recently, it has\ngained the status of gold-standard for protein simulation undergoing\nconformational changes in Martini 3 force field. We discuss several studies\nthat have provided support to this approach in the context of the biophysical\ncommunity.",
        "positive": "Correlations in many-body systems with the Stochastic Variational Method: Few-body correlations often express the distinguishing characteristic\nfeatures of a many-body system. This thesis studies such correlations within\ndilute Bose-Einstein condensates in the case of arbitrary negative s-wave\nscattering length. The N-boson problem is solved by using an ab-initio approach\nbased on correlated Gaussians that allows explicit inclusion of few-body\ncorrelations with a computational complexity that is independent of the number\nof particles. Calculations introducing all higher-order correlations are also\ndone for small systems. In the weakly interacting regime, two-body correlations\nare not only the simplest but also the most important. By varying the\nscattering length and comparing the ground state energy for different\nexplicitly correlated trial wave functions this assumption is investigated\nunder both weakly and strongly interacting conditions."
    },
    {
        "anchor": "Rheological properties of brushes on cancerous epithelial cells under\n  the influence of an external oscillatory force: The rheological properties of brushes of different length on the surface of\nhuman epithelial cancerous cells are studied here by means of coarse grained\nnumerical simulations, where the surface of the cell is subjected to an\nexternal oscillatory force acting on the plane of the cell surface. We model\nexplicitly the tip of an atomic force microscope and the cancerous cell as a\nsurface covered by brushes of different length, and take into account the\ninteractions of the brush chains with the tip and with each other, leading to\ncomplex rheological behavior as displayed by the profiles of viscosity and the\nfriction coefficient of this complex system. We comment briefly on how these\nfindings can help in the experimental effort to understand the nature of the\ncancer growth in human epithelial cells.",
        "positive": "\"Wunderlich, meet Kirchhoff\": A general and unified description of\n  elastic ribbons and thin rods: The equations for the equilibrium of a thin elastic ribbon are derived by\nadapting the classical theory of thin elastic rods. Previously established\nribbon models are extended to handle geodesic curvature, natural out-of-plane\ncurvature, and a variable width. Both the case of a finite width (Wunderlich's\nmodel) and the limit of small width (Sadowksky's model) are recovered. The\nribbon is assumed to remain developable as it deforms, and the direction of the\ngeneratrices is used as an internal variable. Internal constraints expressing\ninextensibility are identified. The equilibrium of the ribbon is found to be\ngoverned by an equation of equilibrium for the internal variable involving its\nsecond-gradient, by the classical Kirchhoff equations for thin rods, and by\nspecific, thin-rod-like constitutive laws; this extends the results of\nStarostin and van der Heijden (2007) to a general ribbon model. Our equations\nare applicable in particular to ribbons having geodesic curvature, such as an\nannulus cut out in a piece of paper. Other examples of application are\ndiscussed. By making use of a material frame rather than the Fr\\'enet-Serret's\nframe, the present work unifies the description of thin ribbons and thin rods."
    },
    {
        "anchor": "Study of network composition in interpenetrating polymer networks of\n  poly(N isopropylacrylamide) microgels:the role of poly(acrylic acid): Hypothesis: The peculiar swelling behaviour of poly(N-isopropylacrylamide)\n(PNIPAM)-based responsive microgels provides the possibility to tune both\nsoftness and volume fraction with temperature, making these systems of great\ninterest for technological applications and theoretical implications. Their\nintriguing phase diagram can be even more complex if poly(acrylic acid) (PAAc)\nis interpenetrated within PNIPAM network to form Interpenetrating Polymer\nNetwork (IPN) microgels that exhibit an additional pH-sensitivity. The effect\nof the PAAc/PNIPAM polymeric ratio on both swelling capability and dynamics is\nstill matter of investigation. Experiments: Here we investigate the role of\nPAAc in the behaviour of IPN microgels across the volume phase transition\nthrough dynamic light scattering (DLS), transmission electron microscopy (TEM)\nand electrophoretic measurements as a function of microgel concentration and\npH. Findings: Our results highlight that aggregation is favored at increasing\nweight concentration, PAAc content and pH and that a crossover PAAc content\nC*_{PAAc} exists above which the ionic charges on the microgel become relevant.\nMoreover we show that the softness of IPN microgels can be tuned ad hoc by\nchanging the PAAc/PNIPAM ratio. These findings provide new insights into the\npossibility to control experimentally aggregation properties, charge and\nsoftness of IPN microgels by varying PAAc content.",
        "positive": "Cation Transport in Polymer Electrolytes: A Microscopic Approach: A microscopic theory for cation diffusion in polymer electrolytes is\npresented. Based on a thorough analysis of molecular dynamics simulations on\nPEO with LiBF$_4$ the mechanisms of cation dynamics are characterised. Cation\njumps between polymer chains can be identified as renewal processes. This\nallows us to obtain an explicit expression for the lithium ion diffusion\nconstant D_{Li} by invoking polymer specific properties such as the Rouse\ndynamics. This extends previous phenomenological and numerical approaches. In\nparticular, the chain length dependence of D_{Li} can be predicted and compared\nwith experimental data. This dependence can be fully understood without\nreferring to entanglement effects."
    },
    {
        "anchor": "Smart helical structures inspired by the pellicle of euglenids: This paper deals with a concept for a reconfigurable structure bio-inspired\nby the cell wall architecture of euglenids, a family of unicellular protists,\nand based on the relative sliding of adjacent strips. Uniform sliding turns a\ncylinder resulting from the assembly of straight and parallel strips into a\ncylinder of smaller height and larger radius, in which the strips are deformed\ninto a family of parallel helices. We examine the mechanics of this cylindrical\nassembly, in which the interlocking strips are allowed to slide freely at their\njunctions, and compute the external forces (axial force and axial torque at the\ntwo ends, or pressure on the lateral surface) necessary to drive and control\nthe shape changes of the composite structure. Despite the simplicity of the\nstructure, we find a remarkably complex mechanical behaviour that can be tuned\nby the spontaneous curvature or twist of the strips.",
        "positive": "Probing the Structure and in Silico Stability of Cargo Loaded DNA\n  Icosahedron using MD Simulations: Platonic solids such as polyhedra based on DNA have been deployed for\nmultifarious applications such as RNAi delivery, biological targeting and\nbioimaging. All of these applications hinge on the capability of DNA polyhedra\nfor molecular display with high spatial precision. Therefore high resolution\nstructural models of such polyhedra are critical to widen their applications in\nboth materials and biology. Here, we present an atomistic model of a\nwell-characterized DNA icosahedron, with demonstrated versatile functionalities\nin biological systems. We study the structure and dynamics of this DNA\nicosahedron using fully atomistic molecular dynamics simulation in explicit\nwater and ions. The major modes of internal motion have been identified using\nprincipal component analysis. We provide a quantitative estimate of the radius\nof gyration (Rg), solvent accessible surface area (SASA) and volume of the\nicosahedron which is essential to estimate its maximal cargo carrying capacity.\nImportantly, our simulation of gold nanoparticles (AuNP) encapsulated within\nDNA icosahedra revealed enhanced stability of the AuNP loaded DNA icosahedra\ncompared to empty icosahedra. This is consistent with experimental results that\nshow high yields of cargo-encapsulated DNA icosahedra that have led to its\ndiverse applications for precision targeting. These studies reveal that the\nstabilizing interactions between the cargo and the DNA scaffold powerfully\npositions DNA polyhedra as targetable nanocapsules for payload delivery. These\ninsights can be exploited for precise molecular display for diverse biological\napplications."
    },
    {
        "anchor": "Sticky Matter: Jamming and rigid cluster statistics with attractive\n  particle interactions: While the large majority of theoretical and numerical studies of the jamming\ntransition consider athermal packings of purely repulsive spheres, real complex\nfluids and soft solids generically display attraction between particles. By\nstudying the statistics of rigid clusters in simulations of soft particles with\nan attractive shell, we present evidence for two distinct jamming scenarios.\nStrongly attractive systems undergo a continuous transition in which rigid\nclusters grow and ultimately diverge in size at a critical packing fraction.\nPurely repulsive and weakly attractive systems jam via a first order\ntransition, with no growing cluster size. We further show that the weakly\nattractive scenario is a finite size effect, so that for any nonzero attraction\nstrength, a sufficiently large system will fall in the strongly attractive\nuniversality class. We therefore expect attractive jamming to be generic in the\nlaboratory and in nature.",
        "positive": "Equation of State of Charged Rod Dispersions: We study the accuracy of the theory of Stroobants, Lekkerkerker and Odijk,\ncalled SLO theory (Macromolecules 19 (1986) 2232-2238), to describe the\nthermodynamic properties of an isotropic fluid of charged rods. By\nincorporation of the effective diameter of the rods according to SLO theory\ninto scaled particle theory (SPT) we obtain an expression for the rod\nconcentration-dependent free volume fraction and the osmotic pressure of a\ncollection of charged hard spherocylinders. The results are compared to Monte\nCarlo simulations. We find close agreement between the simulation results and\nthe SLO-SPT predictions for not too large values of the Debye length and for\nhigh rod charge densities. The deviations increase with rod density,\nparticularly at concentrations above which isotropic-nematic phase transitions\nare expected."
    },
    {
        "anchor": "Polymers for Extreme Conditions Designed Using Syntax-Directed\n  Variational Autoencoders: The design/discovery of new materials is highly non-trivial owing to the\nnear-infinite possibilities of material candidates, and multiple required\nproperty/performance objectives. Thus, machine learning tools are now commonly\nemployed to virtually screen material candidates with desired properties by\nlearning a theoretical mapping from material-to-property space, referred to as\nthe \\emph{forward} problem. However, this approach is inefficient, and severely\nconstrained by the candidates that human imagination can conceive. Thus, in\nthis work on polymers, we tackle the materials discovery challenge by solving\nthe \\emph{inverse} problem: directly generating candidates that satisfy desired\nproperty/performance objectives. We utilize syntax-directed variational\nautoencoders (VAE) in tandem with Gaussian process regression (GPR) models to\ndiscover polymers expected to be robust under three extreme conditions: (1)\nhigh temperatures, (2) high electric field, and (3) high temperature \\emph{and}\nhigh electric field, useful for critical structural, electrical and energy\nstorage applications. This approach to learn from (and augment) human ingenuity\nis general, and can be extended to discover polymers with other targeted\nproperties and performance measures.",
        "positive": "Liquid crystal cells with \"dirty\" substrates: We explore liquid crystal order in a cell with a \"dirty\" substrate imposing a\nrandom surface pinning. Modeling such systems by a random-field xy-model with\nsurface heterogeneity, we find that orientational order in the\nthree-dimensional system is marginally unstable to such surface pinning. We\ncompute the Larkin length scale, and the corresponding surface and bulk\ndistortions. On longer scales we calculate correlation functions using the\nfunctional renormalization group and matching methods, finding a universal\nlogarithmic and double-logarithmic roughness in two and three dimensions,\nrespectively. For a finite thickness cell, we explore the interplay of\nhomogeneous-heterogeneous substrate pair and detail crossovers as a function of\ndisorder strength and cell thickness."
    },
    {
        "anchor": "Thermal transport of confined water molecules in quasi-one-dimensional\n  nanotubes: Dimensions and molecular structure play pivotal roles in the principle of\nheat conduction. The dimensional characteristics of solution within nanoscale\nsystems depend on the degrees of confinement. However, the influence of such\nvariations on heat transfer remains inadequately understood. Here, we perform\nquasi-one-dimensional non-equilibrium molecular dynamics simulations to\ncalculate the thermal conductivity of water molecules confined in carbon\nnanotubes. The structure of water molecules is determined depending on the\nnanotube radius, forming a single-file, a single-layer, and a double-layer\nstructure, corresponding to an increasing radius order. We reveal that the\nthermal conductivity of liquid water has a sublinear dependency on nanotube\nlength exclusively when water molecules form a single file. Stronger\nconfinement leads to behavioral and structural characteristics closely\nresembling a one-dimensional nature. Moreover, single-layer-structure water\nmolecules exhibit enhanced thermal conductivity. We elucidate that this is due\nto the minor vibration of water molecules perpendicular to the heat flux\ndirection and the absence of transitions to another layer that occurs in the\nsystem in which they form a double layer in relatively large radius nanotubes.",
        "positive": "Freezing point depression and freeze-thaw damage by nano-fuidic salt\n  trapping: A remarkable variety of organisms and wet materials are able to endure\ntemperatures far below the freezing point of bulk water. Cryo-tolerance in\nbiology is usually attributed to \"anti-freeze\" proteins, and yet massive\nsupercooling ($< -40^\\circ$C) is also possible in porous media containing only\nsimple aqueous electrolytes. For concrete pavements, the common wisdom is that\nfreeze-thaw damage results from the expansion of water upon freezing, but this\ncannot explain the large pressures ($> 10$~MPa) required to damage concrete,\nthe observed correlation between pavement damage and de-icing salts, or the\ndamage of cement paste loaded with benzene (which contracts upon freezing). In\nthis Letter, we propose a different mechanism -- nanofluidic salt trapping --\nwhich can explain the observations, using simple mathematical models of\ndissolved ions confined to thin liquid films between growing ice and charged\nsurfaces. Although trapped salt lowers the freezing point, ice nucleation in\ncharged pores causes enormous disjoining pressures via the rejected ions, until\ntheir removal by precipitation or surface adsorption at a lower temperatures\nreleases the pressure and allows complete freezing. The theory is able to\npredict the non-monotonic salt-concentration dependence of freeze-thaw damage\nin concreter and provides a general framework to understand the origins of\ncryo-tolerance."
    },
    {
        "anchor": "Strong orientational effect of stretched aerogel on the 3He order\n  parameter: Deformation of aerogel strongly modifies the orientation of the order\nparameter of superfluid 3He confined in aerogel. We used a radial squeezing of\naerogel to keep the orbital angular momentum of the 3He Cooper pairs in the\nplane perpendicular to the magnetic field. We did not find strong evidence for\na \"polar\" phase, with a nodal line along the equator of the Fermi surface,\npredicted to occur at large radial squeezing. Instead we observed 3He-A with a\nclear experimental evidence of the destruction of the long-range order by\nrandom anisotropy -- the Larkin-Imry-Ma effect. In 3He-B we observed and\nidentified new modes of NMR, which are impossible to obtain in bulk 3He-B. One\nof these modes is characterized by a repulsive interaction between magnons,\nwhich is suitable for the magnon Bose-Einstein condensation (BEC).",
        "positive": "Critical exponents of colloid particles in bulk and confinement: Using grand canonical Monte Carlo simulations, we investigate the percolation\nbehavior of a square well fluid with an ultra-short range of attraction in\nthree dimension (3D) and in confined geometry. The latter is defined through\ntwo parallel and structureless walls (slit-pore). We focus on temperatures\nabove the critical temperature of the (metastable) condensation transition of\nthe 3D system. Investigating a broad range of systems sizes, we first determine\nthe percolation thresholds, i. e., the critical packing fraction for\npercolation $\\eta_{c}$. For the slit-pore systems, $\\eta_{c}$ is found to vary\nwith the wall separation $L_{z}$ in a continuous but non-monotonic way,\n$\\eta_{c}(L_{z}\\rightarrow\\infty)=\\eta_{c}^{\\text{3D}}$. We also report results\nfor critical exponents of the percolation transition, specifically, the\nexponent $\\nu$ of the correlation length $\\xi$ and the two fisher exponents\n$\\tau$ and $\\sigma$ of the cluster-size distribution. These exponents are\nobtained from a finite-size analysis involving the cluster-size distribution\nand the radii of gyration distribution at the percolation threshold. Within the\naccuracy of our simulations, the values of the critical exponents of our 3D\nsystem are comparable to those of 3D random percolation theory. For narrow\nslit-pores, the estimated exponents are found to be close to those obtained\nfrom the random percolation theory in two dimensions."
    },
    {
        "anchor": "The physics of dense suspensions: Dense suspensions of particles are relevant to many applications and are a\nkey platform for developing a fundamental physics of out-of-equilibrium\nsystems. They present challenging flow properties, apparently turning from\nliquid to solid upon small changes in composition or, intriguingly, in the\ndriving forces applied to them. The emergent physics close to the ubiquitous\njamming transition (and to some extent the glass and gelation transitions)\nprovides common principles with which to achieve a consistent interpretation of\na vast set of phenomena reported in the literature. In light of this, we review\nthe current state of understanding regarding the relation between the physics\nat the particle scale and the rheology at the macroscopic scale. We further\nshow how this perspective opens new avenues for the development of continuum\nmodels for dense suspensions.",
        "positive": "Harnessing the polymer-particle duality of ultra-soft nanogels to\n  stabilise smart emulsions: Micro- and nanogels are widely used to stabilise emulsions and simultaneously\nimplement their responsiveness to the external stimuli. One of the factors that\nimproves the emulsion stability is the nanogel softness. Here, we study how the\nsoftest nanogels that can be synthesised with precipitation polymerisation of\nN-isopropylacrylamide (NIPAM), the ultra-low crosslinked (ULC) nanogels,\nstabilise oil-in-water emulsions. We show that ULC nanogels can efficiently\nstabilise emulsions already at low mass concentrations. These emulsions are\nresistant to droplet flocculation, stable against coalescence, and can be\neasily broken upon an increase in temperature. The resistance to flocculation\nof the ULC-stabilised emulsion droplets is similar to the one of emulsions\nstabilised by linear pNIPAM. In contrast, the stability against coalescence and\nthe temperature-responsiveness closely resemble the one of emulsions stabilised\nby regularly crosslinked pNIPAM nanogels. The reason for this combination of\nproperties is that ULC nanogels can be thought of as colloids in between\nflexible macromolecules and particles. As a polymer, ULC nanogels can\nefficiently stretch at the interface and cover it uniformly. As a regularly\ncrosslinked nanogel particle, ULC nanogels protect emulsion droplets against\ncoalescence by providing a steric barrier and rapidly respond to changes in\nexternal stimuli thus breaking the emulsion. This polymer-particle duality of\nULC nanogels can be exploited to improve the properties of emulsions for\nvarious applications, for example in heterogeneous catalysis or in food\nscience."
    },
    {
        "anchor": "Vortices near surfaces of Bose-Einstein condensates: The theory of vortex motion in a dilute superfluid of inhomogeneous density\ndemands a boundary layer approach, in which different approximation schemes are\nemployed close to and far from the vortex, and their results matched smoothly\ntogether. The most difficult part of this procedure is the hydrodynamic problem\nof the velocity field many healing lengths away from the vortex core. This\npaper derives and exploits an exact solution of this problem in the\ntwo-dimensional case of a linear trapping potential, which is an idealization\nof the surface region of a large condensate. It thereby shows that vortices in\ninhomogeneous clouds are effectively 'dressed' by a non-trivial distortion of\ntheir flow fields; that image vortices are not relevant to Thomas-Fermi\nsurfaces; and that for condensates large compared to their surface depths, the\nenergetic barrier to vortex penetration disappears at the Landau critical\nvelocity for surface modes.",
        "positive": "Analytic Solution of the Ornstein-Zernike Relation for Inhomogeneous\n  Liquids: The properties of a classical simple liquid can be strongly affected by\napplication of an external potential that supports inhomogeneity. To understand\nthe nature of these property changes the equilibrium particle distribution\nfunctions of the liquid have, typically, been evaluated individually as\nfunctions of system control parameters, such as the packing fraction of a hard\nsphere liquid. In this study we focus attention on two distribution functions\nthat characterize the inhomogeneous liquid: the pair direct correlation\nfunction $c(\\mathbf{r}_1,\\mathbf{r}_2)$ and the pair correlation function\n$g(\\mathbf{r}_1,\\mathbf{r}_2)$. We solve the Ornstein-Zernike equation for the\ninhomogeneous liquid to obtain $c(\\mathbf{r}_1,\\mathbf{r}_2)$ as an explicit\nfunction of $g(\\mathbf{r}_1,\\mathbf{r}_2)$, with the latter considered to be an\nexperimental observable, using information about the well studied and resolved\n$g^0(\\mathbf{r}_1-\\mathbf{r}_2)$ and $c^0(\\mathbf{r}_1-\\mathbf{r}_2)$ for the\nparent homogeneous ($^0$) system. The result obtained with our formulation is\ntested against the exact solutions for the correlation and distribution\nfunctions of a one-dimensional inhomogeneous hard rod liquid. Following the\nsuccess of that test the formalism is extended to obtain\n$c(\\mathbf{r}_1,\\mathbf{r}_2)$ as an explicit function of\n$g(\\mathbf{r}_1,\\mathbf{r}_2)$ in a three dimensional liquid."
    },
    {
        "anchor": "Interactions enhance dispersion in fluctuating channels via emergent\n  flows: Understanding particle motion in narrow channels is essential to guide\nprogress in numerous applications, from filtration to vascular transport.\nThermal or active fluctuations of channel walls for fluid-filled channels can\nslow down or increase the dispersion of tracer particles. Entropic trapping in\nthe wall bulges slows dispersion, and hydrodynamic flows induced by wall\nfluctuations enhance dispersion. Previous studies primarily concentrated on the\ncase of a single Brownian tracer either embedded in an incompressible fluid or\nin the ideal case where the presence of fluid is ignored. Here we address the\nquestion of what happens when there is a large ensemble of interacting Brownian\ntracers -- a common situation in applications. Introducing repulsive\ninteractions between the tracer particles, while ignoring the presence of a\nbackground fluid, leads to an effective flow field. This flow field enhances\ntracer dispersion, a phenomenon strongly reminiscent of that seen in\nincompressible background fluid. We characterise the dispersion by the\nlong-time diffusion coefficient of a single tracer, numerically and\nanalytically with a mean-field density functional analysis. We find a\nsurprising effect where an increased particle density enhances the diffusion\ncoefficient, challenging the notion that crowding effects tend to reduce\ndiffusion. Here, inter-particle interactions push particles closer to the\nfluctuating channel walls. Then, interactions between the fluctuating wall and\nthe now-nearby particles drive particle mixing. Our mechanism is sufficiently\ngeneral that we expect it to apply to various systems. In addition, the\nperturbation theory we derive quantifies dispersion in generic\nadvection-diffusion systems with arbitrary spatiotemporal drift.",
        "positive": "Ordered Morphologies of Confined Diblock Copolymers: We investigate the ordered morphologies occurring in thin-films diblock\ncopolymer. For temperatures above the order-disorder transition and for an\narbitrary two-dimensional surface pattern, we use a Ginzburg-Landau expansion\nof the free energy to obtain a linear response description of the copolymer\nmelt. The ordering in the directions perpendicular and parallel to the surface\nare coupled. Three dimensional structures existing when a melt is confined\nbetween two surfaces are examined. Below the order-disorder transition we find\ntilted lamellar phases in the presence of striped surface fields."
    },
    {
        "anchor": "Evolution of photonic structure on deformation of cholesteric elastomers: We subject a monodomain cholesteric liquid crystal elastomer to uniaxial\nstrain perpendicular to its helical axis and study the response of its texture\nto deformation. A combination of mechanical, optical and X-ray scattering\nmeasurements confirms the prediction for the director rotation, coarsening and\nthen unwinding the cholesteric helix. The study of optical absorption of\ncircularly polarised light quantifies the complex dependence of the photonic\nbandgap structure on strain and directly relates to the microscopic deformation\nof elastomer. Agreement is found with the recently proposed theoretical\nprediction of the photonic structure of cholesteric elastomers.",
        "positive": "Topological defects at smectic interfaces as a potential tool for the\n  biosensing of living microorganisms: Characterizing the anchoring properties of smectic liquid crystals (LCs) in\ncontact with bacterial solutions is crucial for developing biosensing\nplatforms. In this study, we investigate the anchoring properties of a smectic\nLC when exposed to Bacillus Subtilis and Escherichia coli bacterial solutions\nusing interfaces with known anchoring properties. By monitoring the optical\nresponse of the smectic film, we successfully distinguish different types of\nbacteria, leveraging the distinct changes in the LC's response. Through a\ncomprehensive analysis of the interactions between bacterial proteins and the\nsmectic interface, we elucidate the potential underlying mechanisms responsible\nfor these optical changes. Additionally, we introduce the utilization of\ntopological defects; the focal conic domains (FCDs), at the smectic interface\nas an indicative measure of the bacterial concentration. Our findings\ndemonstrate the significant potential of smectic LCs and their defects for\nbiosensing applications and contribute to our understanding of bacteria- LC\ninteractions, paving the way for advancements in pathogen detection and\nprotein-based sensing."
    },
    {
        "anchor": "Dynamic and rate-dependent yielding behavior of Co0.9Ni0.1 nanocluster\n  based magnetorheological fluids: In this paper we performed steady shear and oscillatory magnetorheological\n(MR) studies in magnetic fluids containing CoNi nanoclusters of 450 nm in\ndiameter. Co-rich nanoclusters were synthesized by conventional homogeneous\nnucleation without any external surfactant or reducing agent in liquid polyol\nat elevated temperature. The x-ray diffraction, energy dispersive X-Ray\nanalysis, scanning and transmission electron microscopy studies were done for\nanalyzing the sample composition and morphology. Two variants of fluid samples\nwere prepared by dispersing 15 vol% and 20 Vol% of CoNi powders in castor oil.\nRoom temperature steady magnetoshear studies indicate viscoplastic behavior\nwith stronger dependence of static yield stress on magnetization than a dipolar\ncoupling that was operational in the dynamic yield stress. Magnetosweep\nmeasurements at constant shear rate showed interesting relaxation at high\nmagnetic fields. We also explored dynamical elastic behavior through\noscillatory magnetorheological studies under both strain sweep and frequency\nsweep modes, and showed glass transition like phenomenon occurring in them\nabove critical shear amplitudes.",
        "positive": "Creation of a molecular condensate by dynamically melting a\n  Mott-insulator: We propose creation of a molecular Bose-Einstein condensate (BEC) by loading\nan atomic BEC into an optical lattice and driving it into a Mott insulator (MI)\nwith exactly two atoms per site. Molecules in a MI state are then created under\nwell defined conditions by photoassociation with essentially unit efficiency.\nFinally, the MI is melted and a superfluid state of the molecules is created.\nWe study the dynamics of this process and photoassociation of tightly trapped\natoms."
    },
    {
        "anchor": "Complex crystalline structures in a two-dimensional core-softened system: A cascade of phase transitions from square to hexagonal lattice is studied in\n2D system of particles interacting via core-softened potential. Due to the\npresence of two length-scales of repulsion, different local configurations with\nfour, five, and six neighbors enable, leading to formation of complex crystals.\nThe previously proposed interpolation method is generalized for calculation of\npair correlations in crystals which elemental cell consists of more than one\nparticle. A high efficiency of the method is illustrated using a snub square\nlattice as a representative example. Using molecular dynamics simulations, it\nis found that the snub square lattice is being broken under heating, generating\nhigh density quasicrystalline phase with 12-fold symmetry. Simple theoretical\nmodel is proposed to explain the physical mechanism governing this phenomenon:\nWith density growth (from square to hexagonal phases), the concentrations of\ndifferent local configurations randomly realized through plane tilling are\nbeing changed that minimizes the energy of the system. The calculated phase\ndiagram in the intermediate region of densities justifies the existence of HD12\nphase and demonstrates a cascade of the first-order transitions \"square -- HD12\n-- hexagonal\" solid phases with the density growth. The results allow us to\nbetter understand the physical mechanisms responsive for formation of\nquasicrystals, and, therefore, should be of interest for broad community on\nmaterial science and soft matter.",
        "positive": "Trapping flocking particles with asymmetric obstacles: Asymmetric obstacles can be exploited to direct the motion and induce sorting\nof run-and-tumbling particles. In this work, we show that flocking particles\nwhich follow the Vicsek model aligning rules experience a collective trapping\nin the presence of a wall of funnels made of chevrons, concentrating at the\nopposite side of a wall of funnels than run-and-tumbling particles. Flocking\nparticles can be completely trapped or exhibit a dynamical trapping behaviour;\nthese two regimes open the door to the design of a system with two\nperpendicular flows of active particles. This systematic study broaden our\nunderstanding about the emergence of collective motion of microorganisms in\nconfined environments and direct the design of new microfluidics devices able\nto controlthese collective behaviours."
    },
    {
        "anchor": "Emergence of cooperatively reorganizing cluster and super-Arrhenius\n  dynamics of fragile supercooled liquids: In this paper we develop a theory to calculate the structural relaxation time\n{\\tau} {\\alpha} of fragile su percooled liquids. Using the information of the\nconfigurational entropy and structure we calculate the number of dynamically\nfree, metastable, and stable neighbors around a central particle. In\nsupercooled liquids the cooperatively reorganizing clusters (CRCs) in which the\nstable neighbors form stable nonchemical bonds with the central particle\nemerge. For an event of relaxation to take place these bonds have to reorganize\nirreversibly; the energy involved in the processes is the effective activation\nenergy of relaxation. The theory brings forth a temperature T a and a temper\nature dependent parameter {\\psi}(T ) which characterize slowing down of\ndynamics on cooling. It is shown that the value of {\\psi}(T ) is equal to 1 for\nT > T a indicating that the underlying microscopic mechanism of relaxation is\ndominated by the entropy driven processes while for T < T a , {\\psi}(T )\ndecreases on cooling indicating the emergence of the energy driven processes.\nThis crossover of {\\psi}(T ) from high to low temperatures explains the\ncrossover seen in {\\tau} {\\alpha} . The dynamics of systems that may have\nsimilar static structure but very different dynamics can be understood in terms\nof {\\psi}(T ). We present results for the Kob-Anderson model for three\ndensities and show that the calculated values of {\\tau} {\\alpha} are in\nexcellent agreement with simulation values for all densities. We also show that\nwhen {\\psi}(T ), {\\tau} {\\alpha} and other quantities are plotted as a function\nof T /T a (or T a /T ) the data collapse on master curves.",
        "positive": "Machine Learning Forecasting of Active Nematics: Active nematics are a class of far-from-equilibrium materials characterized\nby local orientational order of force-generating, anisotropic constitutes.\nTraditional methods for predicting the dynamics of active nematics rely on\nhydrodynamic models, which accurately describe idealized flows and many of the\nsteady-state properties, but do not capture certain detailed dynamics of\nexperimental active nematics. We have developed a deep learning approach that\nuses a Convolutional Long-Short-Term-Memory (ConvLSTM) algorithm to\nautomatically learn and forecast the dynamics of active nematics. We\ndemonstrate our purely data-driven approach on experiments of 2D unconfined\nactive nematics of extensile microtubule bundles, as well as on data from\nnumerical simulations of active nematics."
    },
    {
        "anchor": "Binary crystals in two-dimensional two-component Yukawa mixtures: The zero-temperature phase diagram of binary mixtures of particles\ninteracting via a screened Coulomb pair potential is calculated as a function\nof composition and charge ratio. The potential energy obtained by a Lekner\nsummation is minimized among a variety of candidate two-dimensional crystals. A\nwealth of different stable crystal structures is identified including\n$A,B,AB_2, A_2B, AB_4$ structures [$A$ $(B)$ particles correspond to large\n(small) charge.] Their elementary cells consist of triangular, square or\nrhombic lattices of the $A$ particles with a basis comprising various\nstructures of $A$ and $B$ particles. For small charge asymmetry there are no\nintermediate crystals besides the pure $A$ and $B$ triangular crystals.",
        "positive": "Field-controlling patterns of sheared ferrofluid droplets: We investigate how ferrofluid droplets suspended in a wall-bounded shear flow\ncan organise when subjected to an external magnetic field. By tuning the\nmagnitude of the external magnetic field, we find that the ferrofluid droplets\nform chain-like structures in the flow direction when the magnetic field is\nweak, while forming a crystal-like pattern in a strong magnetic field. We\nprovide the phase diagram and the critical conditions for this chain-to-crystal\ntransition, by applying both numerical simulations and analytic calculations.\nWe also examine how the organised patterns of the ferrofluid droplets can be\ncontrolled by simply changing the direction of the magnetic field. This work\ndemonstrates new aspects of field-controllable ferrofluid droplets as a\nconfigurable and reprocessable metamaterial."
    },
    {
        "anchor": "How does confinement affect the dynamics of viscous vesicles and red\n  blood cells?: Despite its significance in microfluidics, the effect of confinement on the\ntransition from the tank-treading (steady motion) to the tumbling (unsteady\nmotion) dynamical state of deformable micro-particles has not been studied in\ndetail. In this paper, we investigate the dynamics of a single viscous vesicle\nunder confining shear as a general model system for red blood cells, capsules,\nor viscous droplets. The transition from tank-treading to tumbling motion can\nbe triggered by the ratio between internal and external fluid viscosities.\nHere, we show that the transition can be induced solely by reducing the\nconfinement, keeping the viscosity contrast constant. The observed dynamics\nresults from the variation of the relative importance of viscous-, pressure-,\nand lubrication-induced torques exerted upon the vesicle. Our findings are of\ninterest for designing future experiments or microfluidic devices: the\npossibility to trigger the tumbling-to-tank-treading transition either by\ngeometry or viscosity contrast alone opens attractive possibilities for\nmicrorheological measurements as well as the detection and diagnosis of\ndiseased red blood cells in confined flow.",
        "positive": "Liquid-crystal patterns of rectangular particles in a square nanocavity: Using density-functional theory in the restricted-orientation approximation,\nwe analyse the liquid-crystal patterns and phase behaviour of a fluid of hard\nrectangular particles confined in a two-dimensional square nanocavity of side\nlength $H$ composed of hard inner walls. Patterning in the cavity is governed\nby surface-induced order, capillary and frustration effects, and depends on the\nrelative values of particle aspect ratio $\\kappa\\equiv L/\\sigma$, with $L$ the\nlength and $\\sigma$ the width of the rectangles ($L\\ge\\sigma$), and cavity size\n$H$. Ordering may be very different from bulk ($H\\to\\infty$) behaviour when $H$\nis a few times the particle length $L$ (nanocavity). Bulk and confinement\nproperties are obtained for the cases $\\kappa=1$, 3 and 6. In the confined\nfluid surface-induced frustration leads to four-fold symmetry breaking in all\nphases (which become two-fold symmetric). Since no director distorsion can\narise in our model by construction, frustration in the director orientation is\nrelaxed by the creation of domain walls (where the director changes by\n$90^{\\circ}$); this configuration is necessary to stabilise periodic phases.\nFor $\\kappa=1$ the crystal becomes stable with commensuration transitions\ntaking place as $H$ is varied. In the case $\\kappa=3$ the commensuration\ntransitions involve columnar phases with different number of columns. Finally,\nin the case $\\kappa=6$, the high-density region of the phase diagram is\ndominated by commensuration transitions between smectic structures; at lower\ndensities there is a symmetry-breaking isotropic $\\to$ nematic transition\nexhibiting non-monotonic behaviour with cavity size."
    },
    {
        "anchor": "Scaling and spontaneous symmetry restoring of topological defect\n  dynamics in liquid crystal: Topological defects -- locations of local mismatch of order -- are a\nuniversal concept playing important roles in diverse systems studied in physics\nand beyond, including the universe, various condensed matter systems, and\nrecently, even life phenomena. Among these, liquid crystal has been a platform\nfor studying topological defects via visualization, yet it has been a challenge\nto resolve three-dimensional structures of dynamically evolving singular\ntopological defects. Here, we report a direct confocal observation of nematic\nliquid crystalline defect lines, called disclinations, relaxing from an\nelectrically driven turbulent state. We focus in particular on reconnections,\ncharacteristic of such line defects. We find a scaling law for in-plane\nreconnection events, by which the distance between reconnecting disclinations\ndecreases by the square root of time to the reconnection. Moreover, we show\nthat apparently asymmetric dynamics of reconnecting disclinations is actually\nsymmetric in a comoving frame, in marked contrast to the two-dimensional\ncounterpart whose asymmetry is established. We argue, with experimental\nsupports, that this is because of energetically favorable symmetric twist\nconfigurations that disclinations take spontaneously, thanks to the topology\nthat allows for rotation of the winding axis. Our work illustrates a general\nmechanism of such spontaneous symmetry restoring that may apply beyond liquid\ncrystal, which can take place if topologically distinct asymmetric defects in\nlower dimensions become homeomorphic in higher dimensions and if the symmetric\nintermediate is energetically favorable.",
        "positive": "Critical behavior of a colloid-polymer mixture confined between walls: We investigate the influence of confinement on phase separation in\ncolloid-polymer mixtures. To describe the particle interactions, the\ncolloid-polymer model of Asakura and Oosawa [J. Chem. Phys. 22, 1255 (1954)] is\nused. Grand canonical Monte Carlo simulations are then applied to this model\nconfined between two parallel hard walls, separated by a distance D=5 colloid\ndiameters. We focus on the critical regime of the phase separation and look for\nsigns of crossover from three-dimensional (3D) Ising to two-dimensional (2D)\nIsing universality. To extract the critical behavior, finite size scaling\ntechniques are used, including the recently proposed algorithm of Kim et al.\n[Phys. Rev. Lett. 91, 065701 (2003)]. Our results point to effective critical\nexponents that differ profoundly from 3D Ising values, and that are already\nvery close to 2D Ising values. In particular, we observe that the critical\nexponent beta of the order parameter in the confined system is smaller than in\n3D bulk, yielding a flatter binodal. Our results also show an increase in the\ncritical colloid packing fraction in the confined system with respect to the\nbulk. The latter seems consistent with theoretical expectations, although\nsubtleties due to singularities in the critical behavior of the coexistence\ndiameter cannot be ruled out."
    },
    {
        "anchor": "Comment on \"Explicit Analytical Solution for Random Close Packing in\n  $d=2$ and $d=3$\": I comment on Zaccone, Phys. Rev. Lett. {\\bf 128}, 028002 (2022) highlighting\na flaw in the derivation that led to a spurious divergent factor. This renders\nthe derivation of the random close packing density invalid.",
        "positive": "Plane-wave approach to the exact van der Waals interaction between\n  colloid particles: The numerically exact evaluation of the van der Waals interaction, also known\nas Casimir interaction when including retardation effects, constitutes a\nchallenging task. We present a new approach based on the plane-wave basis and\ndemonstrate that it possesses advantages over the more commonly used multipole\nbasis. The rotational symmetry of the plane-sphere and sphere-sphere geometries\ncan be exploited by means of a discrete Fourier transform. The new technique is\napplied to a study of the interaction between a colloid particle made of\npolystyrene or mercury and another polystyrene sphere or a polystyrene wall in\nan aqueous solution. Special attention is paid to the influence of screening\ncaused by a variable salt concentration in the medium. It is found that in\nparticular for low salt concentrations the error implied by the proximity force\napproximation is larger than usually assumed. For a mercury droplet, a\nrepulsive interaction is found for sufficiently large distances provided\nscreening is negligible. We emphasize that the effective Hamaker parameter\ndepends significantly on the scattering geometry on which it is based."
    },
    {
        "anchor": "Phase diagrams of colloidal spheres with a constant zeta-potential: We study suspensions of colloidal spheres with a constant zeta-potential\nwithin Poisson-Boltzmann theory, quantifying the discharging of the spheres\nwith increasing colloid density and decreasing salt concentration. We use the\ncalculated renormalized charge of the colloids to determine their pairwise\neffective screened-Coulomb repulsions. Bulk phase diagrams in the colloid\nconcentration-salt concentration representation follow, for various\nzeta-potentials, by a mapping onto published fits of phase boundaries of\npoint-Yukawa systems. Although the resulting phase diagrams do feature\nface-centered cubic (fcc) and body-centered cubic (bcc) phases, they are\ndominated by the (re-entrant) fluid phase due to the colloidal discharging with\nincreasing colloid concentration and decreasing salt concentration.",
        "positive": "Charge Separation at Interfaces of Phase-Separated Coacervates: We present a theory for phase-separated liquid coacervates with salt, taking\ninto account spatial heterogeneities and interfacial profiles. We find that\ncharged layers of alternating sign can form around the interface while the bulk\nphases remain approximately charge-neutral. We show that the salt concentration\nregulates the number of layers and the amplitude of the layer's charge density\nand electrostatic potential. Such charged layers can either repel or attract\nsingle-charged molecules diffusing across the interface. Our theory could be\nrelevant for artificial systems and biomolecular condensates in cells. Our work\nsuggests that interfaces of biomolecular condensates could mediate\ncharge-specific transport similar to membrane-bound compartments."
    },
    {
        "anchor": "Theory of depletion induced phase transition from chiral smectic A\n  twisted ribbons to semi-infinite flat membranes: We consider a theoretical model for the chiral smectic A twisted ribbons\nobserved in assemblies of fd viruses condensed by depletion forces. The\ndepletion interaction is modeled by an edge energy assumed to be proportional\nto the depletant polymer in solution. Our model is based on the Helfrich energy\nfor surface bending and the de Gennes model of chiral smectic A liquid crystals\nwith twist penetration at the edge. We consider two variants of this model, one\nwith the conventional Helfrich Gaussian curvature term, and a second with\nsaddle-splay energy. A mean field analysis of both models yields a first-order\nphase transition between ribbons and semi-infinite flat membranes as the edge\nenergy is varied. The phase transition line and tilt angle profile are found to\nbe nearly identical for the two models; the pitch of the ribbon, however, does\nshow some differences. Our model yields good qualitative agreement with\nexperimental observations if the sign of the Gaussian curvature or saddle-splay\nmodulus is chosen to favor negative Gaussian curvature.",
        "positive": "Colloidal attraction induced by a temperature gradient: Colloidal crystals are of extreme importance for applied research, such as\nphotonic crystals technology, and for fundamental studies in statistical\nmechanics. Long range attractive interactions, such as capillary forces, can\ndrive the spontaneous assembly of such mesoscopic ordered structures. However\nlong range attractive forces are very rare in the colloidal realm. Here we\nreport a novel strong and long ranged attraction induced by a thermal gradient\nin the presence of a wall. Switching on and off the thermal gradient we can\nrapidly and reversibly form stable hexagonal 2D crystals. We show that the\nobserved attraction is hydrodynamic in nature and arises from thermal induced\nslip flow on particle surfaces. We used optical tweezers to directly measure\nthe force law and compare it to an analytic prediction based on Stokes flow\ndriven by Marangoni forces."
    },
    {
        "anchor": "Spontaneous pattern growth on chocolate surface: simulation and\n  experiments: The natural variation of temperature at ambient conditions produces\nspontaneous patterns on the surface of chocolate, which result from fat bloom.\nThese patterns are peculiar because of their shape and cannot be obtained by\ncontrolled temperature conditions. The formation of these spontaneous grains on\nthe surface of chocolate is studied on experimental and theoretical\ngrounds.Three different kinds of experiments were conducted: observation of\nformed patterns in time, atomic force microscopy of the initial events on the\ngrain formation and rheology of the melted chocolate. The patterns observed in\nour experiments follow the trends described by the Avrami model, which\nconsiders that is possible to define a characteristic time scale that governs\nthe growth of grains starting from germ nuclei. Through computer simulations,\nin the NVT ensemble using a coarse-grained model of triacylglycerides\nmolecules, we studied the process of nucleation that starts the pattern growth\nand that is consistent with the Avrami model.",
        "positive": "SAXS measurements of azobenzene lipid vesicles reveal buffer-dependent\n  photoswitching and quantitative Z->E isomerisation by X-rays: Photoresponsive materials feature properties that can be adjusted near-\ninstantaneously, reversibly, and with high spatiotemporal precision, by light.\nThere is considerable interest in maximising the degree of switching, and in\nmeasuring this degree during illumination in complex environments. We study the\nswitching of photoresponsive lipid membranes that allow precise and reversible\nmanipulation of membrane shape, permeability, and fluidity. Though these\nmacroscopic photoresponses are clear, it is unclear how large the changes of\ntrans/cis ratio are, and whether they can be improved. Here, we used\nsmall-angle X-ray scattering to measure the thickness of photoswitchable lipid\nmembranes, and correlate thickness to trans/cis ratios. This revealed an\nunexpected dependency of photoswitching upon aqueous phase composition,\nhighlighting smaller-than-expected photoswitching with deionized water, and\nshowed thickness variations twice as large as previously observed. Soft X-rays\ncan quantitatively isomerise photolipid membranes to the all- trans state: both\nenabling more powerful X-ray-based membrane control and underlining the role of\nhigh energy X-rays for observation-only soft matter experiments."
    },
    {
        "anchor": "Dissipative effects in odd viscous Stokes flow around a single sphere: Odd viscosity (OV) is a transport coefficient in, for example, fluids of\nself-spinning (active) particles or electrons in an external magnetic field.\nThe key feature of OV is that it does not contribute to dissipation in two\nspatial dimensions. In contrast, we explicitly show that in the\nthree-dimensional case, OV can contribute indirectly to dissipation by\nmodifying the fluid flow. We quantify the dissipation rate of a single\nspherical particle moving through a fluid with OV via an exact analytical\nsolution of the generalised stationary creeping flow equations. Our results\nprovide a novel way to quantify the effects of OV by measuring the solid-body\nmotion of a single spherical particle. Moreover, we explicitly demonstrate how\ncomplex fluids can be designed in terms of their rheological properties by\nmixing passive particles with self-spinning active particles.",
        "positive": "Polymer confinement in undulated membrane boxes and tubes: We consider quantum particle or Gaussian polymer confinement between two\nsurfaces and in cylinders with sinusoidal undulations. In terms of the\nvariational method, we show that the quantum mechanical wave equations have\nlower ground state energy in these geometries under long wavelength\nundulations, where bulges are formed and waves are localized in the bulges. It\nturns out correspondingly that Gaussian polymer chains in undulated boxes or\ntubes acquire higher entropy than in exactly flat or straight ones. These\nphenomena are explained by the uncertainty principle for quantum particles, and\nby a \"polymer confinement rule\" for Gaussian polymers. If membrane boxes or\ntubes are flexible, polymer-induced undulation instability is suggested. We\nfind that the wavelength of undulations at the threshold of instability for a\nmembrane box is almost twice the distance between two walls of the box.\nSurprisingly we find that the instability for tubes begins with a shorter\nwavelength compared to the \"Rayleigh\" area-minimizing instability."
    },
    {
        "anchor": "Ripples and Ripples: We study the morphological evolution of surfaces during ion sputtering and we\ncompare their dynamical roughening with aeolian ripple formation in sandy\ndeserts. We show that, although the two phenomena are physically different,\nthey must obey to similar geometrical constraints and therefore can be\ndescribed within the same theoretical framework. The present theory distinguish\nbetween atoms that stay bounded in the bulk and others that are mobile on the\nsurface. We describe the excavation mechanisms, the adsorption and the surface\nmobility by means of a continuous equation derived from the study of dune\nformation on sand. This approach can explain the different dynamical behaviors\nexperimentally observed in metals or in semiconductors and amorphous systems.\nWe also show that this novel approach can describe the occurrence of ripple\nrotation in the $(x,y)$ plane induced by changes in the sputtering incidence\nangle.",
        "positive": "On Scott-Blair model with time-varying viscosity in linear\n  viscoelasticity: In a recent paper, Zhou et al. studied the time-dependent properties of Glass\nFiber Reinforced Polymers (GFRP) composites by using a new rheological model\nwith a time-variable viscosity coefficient. This rheology is essentially based\non a generalized Scott-Blair model with time-varying viscosity coefficient\ninvolving Riemann-Liouville fractional derivatives. Motivated by this study, in\nthis note we suggest a different generalization of the Scott-Blair model based\non the application of Caputo fractional derivatives of a function with respect\nto another function. This new mathematical approach can be useful in\nviscoelasticity and diffusion processes in order to consider time-dependent\ncoefficients. We are able to find the exact analytic solution of the creep\nexperiment based on our new approach and we can compare it with the results\nobtained by Zhou et al."
    },
    {
        "anchor": "Surfactant-induced rigidity of interfaces: a unified approach to free\n  and dip-coated films: The behavior of thin liquid films is known to be strongly affected by the\npresence of surfactants at the interfaces. The detailed mechanism by which the\nlatter enhance film stability is still a matter of debate, in particular\nconcerning the influence of surface elastic effects on the hydrodynamic\nboundary condition at the liquid/air interfaces. In the present work, \"twin\"\nhydrodynamic models neglecting surfactant transport to the interfaces are\nproposed to describe the coating of films onto a solid plate\n(Landau-Levich-Derjaguin configuration) as well as soap film pulling (Frankel\nconfiguration). Experimental data on the entrained film thickness in both\nconfigurations can be fitted very well using a single value of the surface\nelasticity, which is in good agreement with independent measurements by mean of\nsurface expansion experiments in a Langmuir through. The analysis shows how and\nwhen the soap films or dip coating experiments may be used to precisely and\nsensitively measure the surface elasticity of surfactant solutions.",
        "positive": "Superfragile glassy dynamics of onecomponent system with isotropic\n  potential: competition of diffusion and frustration: We investigate glassy dynamical properties of one component three-dimensional\nsystem of particles interacting via pair repulsive potential by the molecular\ndynamic simulation in the wide region of densities. The glass state is\nsuperfragile and it has high glassforming ability. The glass transition\ntemperature Tg has pronounced minimum at densities where the frustration is\nmaximal."
    },
    {
        "anchor": "An Adaptive Quasi-Continuum Approach for Modeling Fracture in Networked\n  Materials: Application to Modeling of Polymer Networks: Materials with network-like microstructure, including polymers, are the\nbackbone for many natural and human-made materials such as gels, biological\ntissues, metamaterials, and rubbers. Fracture processes in these networked\nmaterials are intrinsically multiscale, and it is computationally prohibitive\nto adopt a fully discrete approach for large scale systems. To overcome such a\nchallenge, we introduce an adaptive numerical algorithm for modeling fracture\nin this class of materials, with a primary application to polymer networks,\nusing an extended version of the Quasi-Continuum method that accounts for both\nmaterial and geometric nonlinearities. In regions of high interest, for example\nnear crack tips, explicit representation of the local topology is retained\nwhere each polymer chain is idealized using the worm like chain model. Away\nfrom these imperfections, the degrees of freedom are limited to a fraction of\nthe network nodes and the network structure is computationally homogenized,\nusing the micro-macro energy consistency condition, to yield an anisotropic\nmaterial tensor consistent with the underlying network structure. A nonlinear\nfinite element framework is used to solve the system where dynamic adaptivity\nallows transition between the continuum and discrete scales. The method enables\naccurate modelling of crack propagation without a priori constraint on the\nfracture energy while maintaining the influence of large-scale elastic loading\nin the bulk. We demonstrate the accuracy and efficiency of the method by\napplying it to study the fracture in different examples of network structures.\nWe further use the method to investigate the effects of network topology and\ndisorder on its fracture characteristics. We discuss the implications of our\nmethod for multiscale analysis of fracture in networked material as they arise\nin different applications in biology and engineering.",
        "positive": "Tuning and jamming reduced to their minima: Inspired by protein folding, we introduce funnels into the complex cost\nfunction landscapes of two processes, the tuning of networks, and the jamming\nof ideal spheres. In both processes, geometrical frustration plays a role --\ntuning pressure differences between pairs of target nodes far from the source\nin a flow network impedes tuning of nearby pairs more than the reverse process,\nwhile unjamming the system in one region can make it more difficult to unjam\nelsewhere. By modifying the cost functions to control the order in which\nfunctions are tuned or regions unjam, we smooth out local minima while leaving\nglobal minima unaffected, significantly increasing the success rate of reaching\nglobal minima."
    },
    {
        "anchor": "Experimental Proof of the Existence of a Bifurcation Process During the\n  undrained test in Clay: Recent papers, based on a new simple incremental modelling which assumes an\n\"isotropic\" response, predicts that the trajectory followed during an undrained\ncompression test exhibits a bifurcation process when the stress field arrives\nat q=M'p', where q stands for the deviatoric stress, p' for the mean stress and\nM' is a coefficient describing friction. This indicates a discontinuous change\nof solution when arriving at q=M'p'. This paper looks at experimental data on\ndense sample obtained at p'=constant, and it shows that the trajectory\n(p'=constant, v=constant) does continue to exist at and beyond the q=M'p'\nplane. So, this demonstrates the validity of the analysis which uses the\nbifurcation theory and this strengthens the proposed modelling. Indeed, this\ndemonstrates the reality of the bifurcation process during undrained\ncompression. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn",
        "positive": "Asymmetric Nanoparticle May Go Active at Room Temperature: Using molecular dynamics simulations, we show that an asymmetrically shaped\nnanoparticle in dilute solution possesses a spontaneously curved trajectory\nwithin finite time interval, instead of the generally expected random walk.\nThis unexpected dynamic behavior has a similarity to that of active matters,\nsuch as swimming bacteria, cells or even fishes, but is of a different physical\norigin. The key to the curved trajectory lies in the non-zero resultant force\noriginated from the imbalance of the collision forces acted by surrounding\nsolvent molecules on the shaped nanoparticle during its orientation regulation.\nTheoretical formulae based on the microscopic observation have been derived to\ndescribe this non-zero force and the resulted motion of the nanoparticle."
    },
    {
        "anchor": "A general mixture equation of state for double bonding carboxylic acids\n  with >= 2 association sites: In this paper we obtain the first general multi-component solution to\nthermodynamic perturbation theory for the case that molecules can participate\nin cyclic double bonds. In contrast to previous authors, we do not restrict\ndouble bonding molecules to a 2-site association scheme. Each molecule in a\nmulti-component mixture can have an arbitrary number of donor and acceptor\nassociation sites. The one restriction on the theory is that molecules can have\nat most one pair of double bonding sites. We also incorporate the effect of\nhydrogen bond cooperativity in cyclic double bonds. We then apply this new\nassociation theory to 2-site and 3 site models for carboxylic acids within the\npolar PC-SAFT equation of state. We demonstrate the accuracy of the approach by\ncomparison to both pure and multi-component phase equilibria data. We also\ndemonstrate that inclusion of hydrogen bond cooperativity has a substantial\neffect on liquid phase hydrogen bonding structure.",
        "positive": "Phase diagram of colloidal hard superballs: from cubes via spheres to\n  octahedra: The phase diagram of colloidal hard superballs, of which the shape\ninterpolates between cubes and octahedra via spheres, is determined by\nfree-energy calculations in Monte Carlo simulations. We discover not only a\nstable face-centered cubic (fcc) plastic crystal phase for near-spherical\nparticles, but also a stable body-centered cubic (bcc) plastic crystal close to\nthe octahedron shape, and in fact even coexistence of these two plastic\ncrystals with a substantial density gap. The plastic fcc and bcc crystals are,\nhowever, unstable in the cube and octahedron limit, suggesting that the rounded\ncorners of superballs play an important role in stablizing the rotator phases.\nIn addition, we observe a two-step melting phenomenon for hard octahedra, in\nwhich the Minkowski crystal melts into a metastable bcc plastic crystal before\nmelting into the fluid phase."
    },
    {
        "anchor": "Length Scale of Correlated Dynamics in Ultra-thin Molecular Glasses: Physical vapor deposition (PVD) is widely used in manufacturing ultra-thin\nlayers of amorphous organic solids. Here, we demonstrate that these films\nexhibit a sharp transition from glassy solid to liquid-like behavior with\nthickness below 30 nm. This liquid-like behavior persists even at temperatures\nwell below the glass transition temperature, T$_{\\mathrm{g}}$. The enhanced\ndynamics in these films can produce large scale morphological features during\nPVD and lead to a dewetting instability in films held at temperatures as low as\nT$_{\\mathrm{g}}$-35 K. We measure the effective viscosity of organic glass\nfilms by monitoring the dewetting kinetics. These measurements combined with\ncooling rate-dependent T$_{\\mathrm{g}}$ measurements show that the apparent\nactivation barrier for rearrangement decreases sharply in films thinner than 30\nnm. These observations suggest long-range facilitation of dynamics induced by\nthe free surface, with dramatic effects on the properties of nano-scale\namorphous materials.",
        "positive": "Concentration and mass dependence of transport coefficients and\n  correlation functions in binary mixtures with high mass-asymmetry: Correlation functions and transport coefficients of self-diffusion and shear\nviscosity of a binary Lennard-Jones mixture with components differing only in\ntheir particle mass are studied up to high values of the mass ratio $\\mu$,\nincluding the limiting case $\\mu=\\infty$, for different mole fractions $x$.\nWithin a large range of $x$ and $\\mu$ the product of the diffusion coefficient\nof the heavy species $D_{2}$ and the total shear viscosity of the mixture\n$\\eta_{m}$ is found to remain constant, obeying a generalized Stokes-Einstein\nrelation. At high liquid density, large mass ratios lead to a pronounced cage\neffect that is observable in the mean square displacement, the velocity\nautocorrelation function and the van Hove correlation function."
    },
    {
        "anchor": "The escape transition in a self-avoiding walk model of linear polymers: A linear polymer grafted to a hard wall and underneath an AFM tip can be\nmodelled in a lattice as a grafted lattice polymer (or self-avoiding walk)\ncompressed underneath a piston approaching the wall. As the piston approaches\nthe wall the increasingly confined polymer escapes from the confined region to\nexplore conformations beside the piston. This conformational change is believed\nto be a phase transition in the thermodynamic limit, and has been argued to be\nfirst order, based on numerical results in reference [12]. In this paper a\nlattice self-avoiding walk model of the escape transition is constructed. It is\nproven that this model has a critical point in the thermodynamic limit\ncorresponding to the escape transition of compressed grafted linear polymers.\nThis result relies on the analysis of ballistic self-avoiding walks in slits\nand slabs in the square and cubic lattices. Additionally, numerical estimates\nof the location of the escape transition critical point is reported based on\nMonte Carlo simulations of self-avoiding walks in slits and in slabs.",
        "positive": "Anomalous diffusion in supercooled liquids: a long-range localisation in\n  particle trajectories: A statistical analysis of the geometries of particle trajectories in the\nsupercooled liquid state is reported. We examine two structurally different\nfragile glass-forming liquids simulated by molecular dynamics. In both liquids,\nthe trajectories are found to exhibit a long-range localisation distinct from\nthe short-range localisation within the cage of nearest neighbours. This novel\ndiffusion anomaly is interpreted as a result of the potential-energy landscape\ntopography of fragile glass-formers where the local energy minima coalesce into\nmetabasins - compact domains with low escape probability."
    },
    {
        "anchor": "Dynamics of elongation of nematic tactoids in an electric field: Nematic tactoids are spindle-shaped droplets of a nematic phase nucleated in\nthe co-existing isotropic phase. According to equilibrium theory, their\ninternal structure and shape are controlled by a balance between the elastic\ndeformation of the director field, induced by the preferred anchoring of that\ndirector field to the interface, and the interfacial free energy. Recent\nexperiments on tactoids of chitin nanocrystals dispersed in water show that\nelectrical fields can very strongly elongate tactoids, at least if the tactoids\nare sufficiently large in volume. However, this observation contradicts the\npredictions of equilibrium theory as well as findings from Monte Carlo\nsimulations that do not show this kind of extreme elongation to take place at\nall. To explain this, we put forward a relaxational model based on the\nOseen-Frank free energy of elastic deformation of a director field coupled to\nan anisotropic surface free energy. In our model, we use two reaction\ncoordinates to describe the director field and the extent of elongation of the\ndroplets, and evaluate the evolution of both as a function of time following\nthe switching on of an electric field. Depending on the relative magnitude of\nthe fundamental relaxation rates associated with the two reaction coordinates,\nwe find that the aspect ratio of the drops may develop a large and very\nlong-lived overshoot before eventually relaxing to the much smaller equilibrium\nvalue. In that case, the response of the curvature of the director field lags\nbehind, explaining the experimental observations. Our theory describes the\nexperimental data reasonably well.",
        "positive": "A Polymer Model with Epigenetic Recolouring Reveals a Pathway for the de\n  novo Establishment and 3D Organisation of Chromatin Domains: One of the most important problems in development is how epigenetic domains\ncan be first established, and then maintained, within cells. To address this\nquestion, we propose a framework which couples 3D chromatin folding dynamics,\nto a \"recolouring\" process modelling the writing of epigenetic marks. Because\nmany intra-chromatin interactions are mediated by bridging proteins, we\nconsider a \"two-state\" model with self-attractive interactions between two\nepigenetic marks which are alike (either active or inactive). This model\ndisplays a first-order-like transition between a swollen, epigenetically\ndisordered, phase, and a compact, epigenetically coherent, chromatin globule.\nIf the self-attraction strength exceeds a threshold, the chromatin dynamics\nbecomes glassy, and the corresponding interaction network freezes. By modifying\nthe epigenetic read-write process according to more biologically-inspired\nassumptions, our polymer model with recolouring recapitulates the\nultrasensitive response of epigenetic switches to perturbations, and accounts\nfor multi-domain conformations, strikingly similar to the\ntopologically-associating-domains observed in eukaryotic chromosomes."
    },
    {
        "anchor": "Beyond Quality and Quantity: Contact Distribution Encodes Frictional\n  Strength: Classically, the quantity of contact area $A_R$ between two bodies is\nconsidered a proxy for the force of friction. However, bond density across the\ninterface - quality of contact - is also relevant, and contemporary debate\noften centers around the relative importance of these two factors. In this\nwork, we demonstrate that a third factor, often overlooked, plays a significant\nrole in static frictional strength: the distribution of contact. We perform\nstatic friction measurements, $\\mu$, on three pairs of solid blocks while\nimaging the contact plane. By using linear regression on hundreds of\nimage-$\\mu$ pairs, we are able to predict future friction measurements with 3\nto 7 times better accuracy than existing benchmarks, including total quantity\nof contact area. Our model has no access to quality of contact, and we\ntherefore conclude that a large portion of the interfacial state is encoded in\nthe spatial distribution of contact, rather than its quality or quantity.",
        "positive": "Shear banding and flow-concentration coupling in colloidal glasses: We report experiments on hard sphere colloidal glasses that reveal a type of\nshear banding hitherto unobserved in soft glasses. We present a scenario that\nrelates this to an instability arising from shear-concentration coupling, a\nmechanism previously thought unimportant in this class of materials. Below a\ncharacteristic shear rate $\\dot\\gamma_c$ we observe increasingly non-linear\nvelocity profiles and strongly localized flows. We attribute this trend to very\nslight concentration gradients (likely to evade direct detection) arising in\nthe unstable flow regime. A simple model accounts for both the observed\nincrease of $\\dot\\gamma_c$ with concentration, and the fluctuations observed in\nthe flow."
    },
    {
        "anchor": "Giant Slip at Liquid-Liquid Interfaces Using Hydrophobic Ball Bearings: Liquid-gas-liquid interfaces stabilized by hydrophobic beads behave as ball\nbearings under shear and exhibit a giant slip. Using a scaling analysis and\nmolecular dynamics simulations we predict that, when the contact angle theta\nbetween the beads and the liquid is large, the slip length diverges as R\nrho(-1) (pi -theta)(-3) where R is the bead radius, and theta is the bead\ndensity. DOI: 10.1103/PhysRevLett.110.104504",
        "positive": "Properties of patchy colloidal particles close to a surface: a Monte\n  Carlo and density functional study: We investigate the behavior of a patchy particle model close to a hard-wall\nvia Monte Carlo simulation and density functional theory (DFT). Two DFT\napproaches, based on the homogeneous and inhomogeneous versions of Wertheim's\nfirst order perturbation theory for the association free energy are used. We\nevaluate, by simulation and theory, the equilibrium bulk phase diagram of the\nfluid and analyze the surface properties for two isochores, one of which is\nclose to the liquid side of the gas-liquid coexistence curve. We find that the\ndensity profile near the wall crosses over from a typical high-temperature\nadsorption profile to a low-temperature desorption one, for the isochore close\nto coexistence. We relate this behavior to the properties of the bulk network\nliquid and find that the theoretical descriptions are reasonably accurate in\nthis regime. At very low temperatures, however, an almost fully bonded network\nis formed, and the simulations reveal a second adsorption regime which is not\ncaptured by DFT. We trace this failure to the neglect of orientational\ncorrelations of the particles, which are found to exhibit surface induced\norientational order in this regime."
    },
    {
        "anchor": "Light scattering study of the \"pseudo-layer\" compression elastic\n  constant in a twist-bend nematic liquid crystal: The nematic twist-bend (TB) phase, exhibited by certain achiral thermotropic\nliquid crystalline (LC) dimers, features a nanometer-scale, heliconical\nrotation of the average molecular long axis (director) with equally probable\nleft- and right-handed domains. On meso to macroscopic scales, the TB phase may\nbe considered as a stack of equivalent slabs or \"pseudo-layers\", each one\nhelical pitch in thickness. The long wavelength fluctuation modes should then\nbe analogous to those of a smectic-A phase, and in particular the hydrodynamic\nmode combining \"layer\" compression and bending ought to be characterized by an\neffective layer compression elastic constant $B_{eff}$ and average director\nsplay constant $K_1^{eff}$. The magnitude of $K_1^{eff}$ is expected to be\nsimilar to the splay constant of an ordinary nematic LC, but due to the absence\nof a true mass density wave, $B_{eff}$ could differ substantially from the\ntypical value of $\\sim 10^6$ Pa in a conventional smectic-A. Here we report the\nresults of a dynamic light scattering study, which confirms the \"pseudo-layer\"\nstructure of the TB phase with $B_{eff}$ in the range $\\sim 10^3-10^4$ Pa. We\nshow additionally that the temperature dependence of $B_{eff}$ at the TB to\nnematic transition is accurately described by a coarse-grained free energy\ndensity, which is based on a Landau-deGennes expansion in terms of a heli-polar\norder parameter that characterizes the TB state and is linearly coupled to bend\ndistortion of the director.",
        "positive": "Deformation characteristics and mechanical properties of a non-rigid\n  square-twist origami structure with rotational symmetry: Non-rigid origami patterns could provide more versatile performance than\ntheir rigid counterparts in the design of mechanical metamaterials owing to the\nsimultaneous deformation of facets and creases, but their complex deformation\nmodes make quantitative characterization and programmability of mechanical\nproperties a challenging task. Here, we investigated the tensile behavior of a\nnon-rigid square-twist origami structure with rotational symmetry by combining\nbiaxial tension experiments and finite element modeling. A three-stage\ndeformation process, including tightening, unlocking, and flattening, of the\nstructure was unveiled through a detailed analysis of facet distortion and\ncrease rotation, and the relationship between structure deformation and several\nkey features in the energy, force, and stiffness curve was obtained. Based on\nthe analysis, an empirical model was built to correlate the geometric and\nmaterial parameters of the structure and its deformation energy, initial peak\nforce, and maximum stiffness, which were further validated through experiments.\nUsing the model, the mechanical properties of the structure can be accurately\npredicted and programmed based on specific engineering requirements, thereby\nserving the development of new programmable mechanical metamaterials based on\nthe family of square-twist origami."
    },
    {
        "anchor": "Fluid velocity slip and temperature jump at a solid surface: A comprehensive review of current analytical models, experimental techniques,\nand influencing factors is carried out to highlight the current challenges in\nthis area. The study of fluid-solid boundary conditions has been ongoing for\nmore than a century, starting from gas-solid interfaces and progressing to that\nof the more complex liquid-solid case. Breakthroughs have been made on the\ntheoretical and experimental fronts but the mechanism behind the phenomena\nremains a puzzle. This paper provides a review of the theoretical models, and\nnumerical and experimental investigations that have been carried out till date.\nProbable mechanisms and factors that affect the interfacial discontinuity are\nalso documented.",
        "positive": "Contact Changes near Jamming: We probe the onset and effect of contact changes in soft harmonic particle\npackings which are sheared quasistatically. We find that the first contact\nchanges are the creation or breaking of contacts on a single particle. We\ncharacterize the critical strain, statistics of breaking versus making a\ncontact, and ratio of shear modulus before and after such events, and explain\ntheir finite size scaling relations. For large systems at finite pressure, the\ncritical strain vanishes but the ratio of shear modulus before and after a\ncontact change approaches one: linear response remains relevant in large\nsystems. For finite systems close to jamming the critical strain also vanishes,\nbut here linear response already breaks down after a single contact change."
    },
    {
        "anchor": "Excitable Patterns in Active Nematics: We analyze a model of mutually-propelled filaments suspended in a\ntwo-dimensional solvent. The system undergoes a mean-field isotropic-nematic\ntransition for large enough filament concentrations and the nematic order\nparameter is allowed to vary in space and time. We show that the interplay\nbetween non-uniform nematic order, activity and flow results in spatially\nmodulated relaxation oscillations, similar to those seen in excitable media. In\nthis regime the dynamics consists of nearly stationary periods separated by\n\"bursts\" of activity in which the system is elastically distorted and solvent\nis pumped throughout. At even higher activity the dynamics becomes chaotic.",
        "positive": "Nucleophilicity/Electrophilicity Excess in Analyzing Molecular\n  Electronics: Intramolecular electron transfer capability of all metal aromatic and\nanti-aromatic aluminum cluster compounds is studied in terms of density\nfunctional theory based global and local reactivity descriptors. This study\nwill provide important inputs towards the fabrication of the material required\nfor molecular electronics."
    },
    {
        "anchor": "Single-file escape of colloidal particles from microfluidic channels: Single-file diffusion is a ubiquitous physical process exploited by living\nand synthetic systems to exchange molecules with their environment. It is\nparamount quantifying the escape time needed for single files of particles to\nexit from constraining synthetic channels and biological pores. This quantity\ndepends on complex cooperative effects, whose predominance can only be\nestablished through a strict comparison between theory and experiments. By\nusing colloidal particles, optical manipulation, microfluidics, digital\nmicroscopy and theoretical analysis we uncover the self-similar character of\nthe escape process and provide closed-formula evaluations of the escape time.\nWe find that the escape time scales inversely with the diffusion coefficient of\nthe last particle to leave the channel. Importantly, we find that at the\ninvestigated {\\bf microscale}, bias forces as tiny as $10^{-15}\\;{\\rm N}$\ndetermine the magnitude of the escape time by drastically reducing\ninterparticle collisions. Our findings provide crucial guidelines to optimize\nthe design of micro- and nano-devices for a variety of applications including\ndrug delivery, particle filtering and transport in geometrical constrictions.",
        "positive": "Extreme thermodynamics with polymer gel tori: harnessing thermodynamic\n  instabilities to induce large-scale deformations: When a swollen, thermoresponsive polymer gel is heated in a solvent bath, it\nexpels solvent and deswells. When this heating is slow, deswelling proceeds\nhomogeneously, as observed in a toroid-shaped gel that changes volume whilst\nmaintaining its toroidal shape. By contrast, if the gel is heated quickly, an\nimpermeable layer of collapsed polymer forms and traps solvent within the gel,\narresting the volume change. The ensuing evolution of the gel then happens at\nfixed volume, leading to phase-separation and the development of inhomogeneous\nstress that deforms the toroidal shape. We observe that this stress can cause\nthe torus to buckle out of the plane, via a mechanism analogous to the bending\nof bimetallic strips upon heating. Our results demonstrate that thermodynamic\ninstabilities, i.e., phase transitions, can be used to actuate mechanical\ndeformation in an extreme thermodynamics of materials."
    },
    {
        "anchor": "Applications of a generalization of the nonlinear sigma model with O(d)\n  group of symmetry to the dynamics of a constrained chain: Subject of this work are the applications of a field theoretical model,\ncalled here generalized nonlinear sigma model or simply GNLSM,to the dynamics\nof a chain subjected to constraints. Chains with similar properties and\nconstraints have been discussed in a seminal paper of Edwards and Goodyear\nusing an approach based on the Langevin equation. The GNLSM has been proposed\nin a previous publication in order to describe the dynamics of a two\ndimensional chain. In this paper the model is extended to d dimensions and a\nbending energy term is added to its action. As an application, two observables\nare computed in the case of a very stiff chain. The first observable is the\ndynamical form factor of a ring shaped chain. The second observable is a\nstraightforward generalization to dynamics of the static form factor. This\nobservable is relevant in order to estimate the average distance between two\narbitrary points of the chain. Finally, a variant of the GNLNM is presented, in\nwhich the topological conditions which constrain the motion of two linked\nchains are imposed with the help of the Gauss linking invariant.",
        "positive": "Motion of small bubbles and drops in viscoelastic fluids: Viscoelastic materials containing bubbles or drops are encountered in\nnumerous application fields, and are presently the object of much interest. The\nmotion of bubbles and drops in these matrices can be significantly different\nthan in Newtonian fluids. This review is restricted to the case of motion in\nquiescent fluids (or small Reynolds number) and of small bubbles and drops,\nthat are not appreciably deformed during their motion. It includes a brief\ndescription of properties of viscoelastic systems and of the motion of solid\nparticles in these systems. The case of very small drops undergoing Brownian\nmotion is related to recent advances in microrheology. The motion of larger\ndrops and bubbles due to gravity in yield stress fluids is discussed and linked\nto Ostwald ripening. Recent advances on the understanding of the rheological\nproperties of the composite systems are also briefly discussed."
    },
    {
        "anchor": "Dipolophoresis in concentrated suspensions of ideally polarizable\n  spheres: The dynamics of ideally polarizable spherical particles in concentrated\nsuspensions under the effects of nonlinear electrokinetic phenomena is analysed\nusing large-scale numerical simulations. Particles are assumed to carry no net\ncharge and considered to undergo the combination of dielectrophoresis and\ninduced-charge electrophoresis termed dipolophoresis. Chaotic motion and\nresulting hydrodynamic diffusion are known to be driven by the induced-charge\nelectrophoresis, which dominates the dielectrophoresis. Up to a volume fraction\n$\\phi \\approx 35\\%$, the particle dynamics seems to be hindered by the increase\nin the magnitude of excluded volume interactions with concentration. However, a\nnon-trivial suspension behaviour is observed in concentrated regimes, where the\nhydrodynamic diffusivity starts to increase with a volume fraction at $\\phi\n\\approx 35\\%$ before reaching a local maximum and then drastically decreases as\napproaching random close packing. Similar non-trivial behaviours are observed\nin the particle velocity and number-density fluctuations around volume\nfractions that the non-trivial behaviour of the hydrodynamic diffusion is\nobserved. We explain these non-trivial behaviours as a consequence of particle\ncontacts, which are related to the dominant mechanism of particle pairings. The\nparticle contacts are classified into attractive and repulsive classes by the\nnature of contacts, and in particular, the strong repulsive contact becomes\npredominant at $\\phi > 20\\%$. Moreover, this transition is visible in the pair\ndistribution functions, which also reveal the change in the suspension\nmicrostructure in concentrated regimes. It appears that strong and massive\nrepulsive contacts along the direction perpendicular to an electric field\npromote the non-trivial suspension behaviours observed in concentrated regimes.",
        "positive": "Quantifying Structural Dynamic Heterogeneity in a Dense Two-dimensional\n  Equilibrium Liquid: We investigate the local structural fluctuations of a model equilibrium fluid\nwith an aim of better understanding the structural basis of locally\nheterogeneous dynamics identified in recent simulations and experimental\nstudies of glass-forming liquids and other strongly interacting particle\nsystems, such as, lipid membranes, dusty plasmas, interfacial dynamics of\ncrystals, internal dynamics of proteins, etc. In particular, we study a\ntwo-dimensional single component Lennard-Jones over a range of densities and\nconstant temperature covering both the liquid and crystalline phase by\nmolecular dynamics simulation. We identify three distinct structural classes of\nparticles by examining the immediate neighborhood of individual particles based\non a solid-angle based tessellation technique. In particular, the area\ndistribution of the neighborhoods reveals cages having hexagonal, pentagonal\nand square symmetries. Pentagonal cells appear to be predominant motif in the\nliquid phase, while the solid phase is dominated by hexagonal cells, as in the\ncase of the perfect crystal. Examining the spatial organization of particles\nbelonging to each structural class separately shows that finite-size clusters\nformed by particles of hexagonal and pentagonal population found within liquids\nand solids, respectively, grow in a complementary way as a function of density\nand both particle populations percolate within liquid-crystal coexistence\nregime. Interestingly, the populations of particles with different local\nstructures, defined by the arrangement of neighboring particles, are found to\nmaintain different diffusivity computed from the velocity autocorrelation of\nconstituent particles for all densities studied. Our analysis provides a new\napproach for analyzing and a possible framework for understanding the\nstructural changes in soft materials."
    },
    {
        "anchor": "Alkali adsorbate polarization on conducting and insulating surfaces\n  probed with Bose-Einstein condensates: A magnetically trapped 87Rb Bose-Einstein condensate is used as a sensitive\nprobe of short-range electrical forces. In particular, the electric\npolarization of, and the subsequent electric field generated by, 87Rb\nadsorbates on conducting and insulating surfaces is measured by characterizing\nperturbations to the magnetic trapping potential using high-Q condensate\nexcitations. The nature of the alterations to the electrical properties of Rb\nadsorbates is studied on titanium (metal) and silicon (semiconductor) surfaces,\nwhich exhibit nearly identical properties, and on glass (insulator), which\ndisplays a smaller transitory electrical effect. The limits of this technique\nin detecting electrical fields and ramifications for measurements of\nshort-range forces near surfaces are discussed.",
        "positive": "Ratcheted diffusion transport through crowded nanochannels: The problem of transport through nanochannels is one of the major questions\nin cell biology, with a wide range of applications. Brownian ratchets are\nfundamental in various biochemical processes, and are roughly divided into two\ncategories: active (usually ATP-powered) molecular motors and passive\nconstructions with a directional bias, where the transport is driven by thermal\nmotion. In this paper we discuss the latter process, of spontaneous\ntranslocation of molecules (Brownian particles) by ratcheted diffusion with no\nexternal energy input: a problem relevant for protein translocation along\nbacterial flagella or injectosome complex, or DNA translocation by\nbacteriophages. We use molecular dynamics simulations and statistical theory to\nidentify two regimes of transport: at low rate of particles injection into the\nchannel the process is controlled by the individual diffusion towards the open\nend (the first passage problem), while at a higher rate of injection the\ncrowded regime sets in. In this regime the particle density in the channel\nreaches a constant saturation level and the resistance force increases\nsubstantially, due to the osmotic pressure build-up. To achieve a steady-state\ntransport, the apparatus that injects new particles into a crowded channel has\nto operate with an increasing power consumption, proportional to the length of\nthe channel and the required rate of transport. The analysis of resistance\nforce, and accordingly -- the power required to inject the particles into a\ncrowded channel to oversome its clogging, is also relevant for many\nmicrofluidics applications."
    },
    {
        "anchor": "Making Faces: Universal Inverse Design of Surfaces with Thin Nematic\n  Elastomer Sheets: Programmable shape-shifting materials can take different physical forms to\nachieve multifunctionality in a dynamic and controllable manner. Although\nmorphing a shape from 2D to 3D via programmed inhomogeneous local deformations\nhas been demonstrated in various ways, the inverse problem -- programming a\nsheet to take an arbitrary desired 3D shape -- is much harder yet critical to\nrealize specific functions. Here, we address this inverse problem in thin\nliquid crystal elastomer (LCE) sheets, where the shape is preprogrammed by\nprecise and local control of the molecular orientation of the liquid crystal\nmonomers. We show how blueprints for arbitrary surface geometries as well as\nlocal extrinsic curvatures can be generated using approximate numerical\nmethods. Backed by faithfully alignable and rapidly lockable LCE chemistry, we\nprecisely embed our designs in LCE sheets using advanced top-down\nmicrofabrication techniques. We thus successfully produce flat sheets that,\nupon thermal activation, take an arbitrary desired shape, such as a face. The\ngeneral design principles presented here for creating an arbitrary 3D shape\nwill allow for exploration of unmet needs in flexible electronics,\nmetamaterials, aerospace and medical devices, and more.",
        "positive": "Crystal nucleation of colloidal hard dumbbells: Using computer simulations we investigate the homogeneous crystal nucleation\nin suspensions of colloidal hard dumbbells. The free energy barriers are\ndetermined by Monte Carlo simulations using the umbrella sampling technique. We\ncalculate the nucleation rates for the plastic crystal and the aperiodic\ncrystal phase using the kinetic prefactor as determined from event driven\nmolecular dynamics simulations. We find good agreement with the nucleation\nrates determined from spontaneous nucleation events observed in event driven\nmolecular dynamics simulations within error bars of one order of magnitude. We\nstudy the effect of aspect ratio of the dumbbells on the nucleation of plastic\nand aperiodic crystal phases and we also determine the structure of the\ncritical nuclei. Moreover, we find that the nucleation of the aligned CP1\ncrystal phase is strongly suppressed by a high free energy barrier at low\nsupersaturations and slow dynamics at high supersaturations."
    },
    {
        "anchor": "Sonic shrinking of Pickering-stabilised ultrasound contrast agent at a\n  low acoustic amplitude: Ultrasound contrast agents comprise gas microbubbles surrounded by\nstabilising elastic or viscoelastic shells. Microbubbles containing liquid or\nsolid cores are referred to as antibubbles. The manufacturing process of\nlong-lived antibubbles involves the adsorption of colloidal particles at the\ninterfaces, a process called Pickering stabilisation. With and without cores\npresent inside, Pickering-stabilised microbubbles generate a harmonic response,\neven at modest transmission amplitudes. Therefore, Pickering-stabilised\nultrasound contrast agents may be of interest in contrast-enhanced ultrasonic\nimaging. In a previous study, we determined that the presence of a core inside\nPickering-stabilised microbubbles slightly hampered the oscillation amplitude\ncompared to identical microbubbles without a core. The purpose of the present\nstudy is to determine whether the absence of a core negatively influences the\nstability of Pickering-stabilised microbubbles under sonication.",
        "positive": "Soft granular matter: We consider a dilute system of small hard beads or hard fibers immersed in a\nvery soft gel able to withstand large elastic deformations. Because of its low\nto very low shear modulus, this system is very sensitive to small forces. We\ncalculate the local deformation induced by a constant volume force, the\ninclusion weight. We explain how this deformation could be put in evidence by\nusing techniques similar to the PIV method (particle image velocimetry) used to\nshow complex velocity fields in transparent fluids."
    },
    {
        "anchor": "A numerical study of longtime dynamics and ergodic-nonergodic\n  transitions in dense simple fluids: For over 30 years, mode-coupling theory (MCT) has been the de facto theoretic\ndescription of dense fluids and the liquid-glass transition. MCT, however, is\nlimited by its ad hoc construction and lacks a mechanism to institute\ncorrections. We use recent results from a new theoretical framework--developed\nfrom first principles via a self-consistent perturbation expansion in terms of\nan effective two-body potential--to numerically explore the kinetics of systems\nof classical particles, specifically hard spheres obeying Smoluchowski\ndynamics. We present here a full solution to the kinetic equation governing the\ndensity-density time correlation function and show that the function exhibits\nthe characteristic two-step decay of supercooled fluids and an\nergodic-nonergodic transition to a dynamically-arrested state. Unlike many\nprevious numerical studies and experiments, we have access to the full time and\nwavenumber range of the correlation function and can track the solution\nunprecedentedly close to the transition, covering nearly 15 decades of time.\nUsing asymptotic approximation techniques developed for MCT, we fit the\nsolution to predicted forms and extract critical parameters. Our solution shows\na transition at packing fraction $\\eta^*=0.60149761(10)$--consistent with\nprevious static solutions under this theory and with comparable colloidal\nsuspension experiments--and the behavior in the $\\beta$-relaxation regime is\nfit to power-law decays with critical exponents $a=0.375(3)$ and $b=0.8887(4)$,\nand with $\\lambda=0.5587(18)$. For the $\\alpha$-relaxation of the ergodic\nphase, we find a power-law divergence of the time scale $\\tau_{\\alpha}$ as we\napproach the transition. Through these results, we establish that this new\ntheory is able to reproduce the salient features of MCT, but has the advantages\nof a first principles derivation and a clear mechanism for making systematic\nimprovements.",
        "positive": "Reversible shear thickening at low shear rates of electrorheological\n  fluids under electric fields: Shear thickening is a phenomenon of significant viscosity increase of\ncolloidal suspensions. While electrorheological (ER) fluids can be turned into\na solid-like material by applying an electric field, their shear strength is\nwidely represented by the attractive electrostatic interaction between ER\nparticles. By shearing ER fluids between two concentric cylinders, we show a\nreversible shear thickening of ER fluids above a low critical shear rate (<1\ns-1) and a high critical electric field strength (>100 V/mm), which could be\ncharacterized by a modified Mason number. Shear thickening and electrostatic\nparticle interaction-induced inter-particle friction forces is considered to be\nthe real origin of the high shear strength of ER fluids, while the applied\nelectric field controls the extent of shear thickening. The electric\nfield-controlled reversible shear thickening has implications for\nhigh-performance ER/magnetorheological (MR) fluid design, clutch fluids with\nhigh friction forces triggered by applying local electric field, other\nfield-responsive materials and intelligent systems."
    },
    {
        "anchor": "Multi-angle holographic characterization of individual fractal\n  aggregates: Holographic particle characterization uses quantitative analysis of\nholographic microscopy data to precisely and rapidly measure the diameter and\nrefractive index of individual colloidal spheres in their native media. When\nthis technique is applied to inhomogeneous or aspherical particles, the\nmeasured diameter and refractive index represent properties of an effective\nsphere enclosing each particle. Effective-sphere analysis has been applied\nsuccessfully to populations of fractal aggregates, yielding an overall fractal\ndimension for the population as a whole. Here, we demonstrate that holographic\ncharacterization also can measure the fractal dimensions of an individual\nfractal cluster by probing how its effective diameter and refractive index\nchange as it undergoes rotational diffusion. This procedure probes the\nstructure of a cluster from multiple angles and thus constitutes a form of\ntomography. Here we demonstrate and validate this effective-sphere\ninterpretation of aspherical particles' holograms through experimental studies\non aggregates of silica nanoparticles grown under a range of conditions.",
        "positive": "Structural evolution of a granular pack under manual tapping: We experimentally study a two-dimensional (2D) granular pack of photoelastic\ndisks subject to vertical manual tapping. Using bright and dark field images,\nwe employ gradient-based image analysis methods to analyse various structural\nquantities. These include the packing fraction ($\\phi$), force per disk ($F_d$)\nand force chain segment length ($l$) as a function of the tapping number\n($\\tau$). The increase in packing fraction with tapping number is found to\nexponentially approach an asymptotic value. An exponential distribution is\nobserved for both the cumulative numbers of force per disk $F_d$ :\n$N_{cum}(F_d) = A_F \\exp (-\\frac{F_d}{F_0})$, and force chain segment length\n$l$ : $N_{cum}(l) = A_l \\exp (-\\frac{l}{l_0})$. Whereas the coefficient ${A_F}$\nvaries with $\\tau$ for force per disk, the force chain segment length shows no\ndependence on $\\tau$. The $\\tau$ dependence of $F_d$ and $\\phi$ allows us to\nposit a linear relation between the total force of the granular pack\n($F_{tot}^*(\\tau)$) and $\\phi(\\tau)$."
    },
    {
        "anchor": "New patterns in high-speed granular flows: We report on new patterns in high-speed flows of granular materials obtained\nby means of extensive numerical simulations. These patterns emerge from the\ndestabilization of unidirectional flows upon increase of mass holdup and\ninclination angle, and are characterized by complex internal structures\nincluding secondary flows, heterogeneous particle volume fraction, symmetry\nbreaking and dynamically maintained order. In particular, we evidenced steady\nand fully developed \"supported\" flows, which consist of a dense core surrounded\nby a highly energetic granular gas. Interestingly, despite their overall\ndiversity, these regimes are shown to obey a scaling law for the mass flow rate\nas a function of the mass holdup. This unique set of 3D flow regimes raises new\nchallenges for extending the scope of current granular rheological models.",
        "positive": "Early time evolution of Freedericks patterns generated from states of\n  electroconvection: We report on the early time ordering in a nematic liquid crystal subjected to\na sudden change in external ac electric field. We compare time evolution for\ntwo different initial states of electroconvection. Electroconvection is a\nhighly driven state of a nematic liquid crystal involving convective motion of\nthe fluid and periodic variations of the molecular alignment. By suddenly\nchanging either the voltage or the frequency of the applied ac field, the\nsystem is brought to the same thermodynamic conditions. The time ordering of\nthe system is characterized by the evolution of features of the power spectrum,\nincluding the average wavenumber, total power, and shape of the the power\nspectrum. The differences between the two classes of quenches are discussed, as\nwell as the possibility of scaling behavior during this initial phase of domain\ngrowth."
    },
    {
        "anchor": "Micro-slips inside a granular shear band as nano-earthquakes: We study experimentally the fluctuations of deformation along a shear fault\nnaturally emerging within a compressed frictional granular medium. Using laser\ninterferometry, we show that the deformation inside this granular gouge occurs\nas a succession of localized micro-slips distributed along the fault. The\nassociated distributions of released seismic moments, the memory effects in\nstrain fluctuations, as well as the time correlations between successive\nevents, follow exactly the empirical laws of natural earthquakes. Using a\nmethodology initially developed in seismology and social science, we reveal,\nfor the first time at the laboratory scale, the underlying causal structure.\nThis demonstrates that the spatio-temporal correlations of the slip dynamics\neffectively emerge from more fundamental triggering kernels. This formal\nanalogy between natural faults and our experimentally controllable granular\nshear band opens the way towards a better understanding of earthquake physics.\nIn particular, comparing experiments performed under different imposed\ndeformation rates, we show that strain, not time, is the right parameter\ncontrolling the memory effects in the dynamics of our fault analog. This raises\nthe fundamental question of the relative roles of strain-dependent structural\nrearrangements within the fault gouge vs that of truly time-dependent,\nthermally activated processes, in the emergence of spatio-temporal correlations\nof natural seismicity.",
        "positive": "A new approach for the interpretation of the dynamic and mechanical\n  properties of polymer nanocomposites above and below the glass transition\n  region: In this work, we present a new model for the interpretation of the local\ndynamic behavior and the mechanical reinforcement mechanism in polymer\nnanocomposites. The temperature dependence of the dynamics in the glassy region\nis described by a new equation which assumes an Arrhenius component in the\ncooperative diffusion. By doing so, a characteristic temperature which can be\nidentified as the glass transition temperature (Tg) emerges, while an\nadditional parameter for the extension of the super-Arrhenius region is\nincorporated. Based on thermodynamic arguments, the dynamical heterogeneities\nare then related to structural heterogeneities in a manner consistent with the\nidea of a sigmoidal shape in the cohesion energy. Incorporation of this\ntemperature dependence of the cohesion energy to a Sanchez-Lacombe Equation of\nState, results in a sound description of the experimental temperature and\npressure dependence of the density. Moreover, comparison with experimental data\nshows that the enhancement of mechanical properties in polymer nanocomposites\ncan be associated with the extent of the glassy region."
    },
    {
        "anchor": "Bell Rate Model with Dynamic Disorder: Model and Its Application in the\n  Receptor-ligand Forced Dissociation Experiments: We extend the Bell forced dissociation rate model to take account into\ndynamic disorder. The motivation of the present work is from the recent forced\ndissociation experiments of the adhesive receptor-ligand complexes, in which\nsome complexes were found to increase their mean lifetimes (catch bonds) when\nthey are stretched by mechanical force, while the force increases beyond some\nthresholds their lifetimes decrease (slip bonds). Different from our previous\nmodel of force modulating dynamic disorder, in present work we allow that the\nprojection of force onto the direction from the bound to the transition state\nof complex could be negative. Our quantitative description is based on a\none-dimension diffusion-assisted reaction model. We find that, although the\nmodel can well describe the catch-slip transitions observed in the single bond\nP-selctin glycoprotein ligand 1(PSGL-1)-P- and L-selectin forced dissociation\nexperiments, it might be physically unacceptable because the model predicts a\nslip-catch bond transitions when the conformational diffusion coefficient tends\nto zero.",
        "positive": "Topological Defects in Spherical Nematics: We study the organization of topological defects in a system of nematogens\nconfined to the two-dimensional sphere (S^2). We first perform Monte Carlo\nsimulations of a fluid system of hard rods (spherocylinders) living in the\ntangent plane of S^2. The sphere is adiabatically compressed until we reach a\njammed nematic state with maximum packing density. The nematic state exhibits\nfour +1/2 disclinations arrayed on a great circle rather than at the vertices\nof a regular tetrahedron. This arises from the high elastic anisotropy of the\nsystem in which splay (K_1) is far softer than bending (K_3). We also introduce\nand study a lattice nematic model on S^2 with tunable elastic constants and map\nout the preferred defect locations as a function of elastic anisotropy. We\nestablish the existence of a one-parameter family of degenerate ground states\nin the extreme splay-dominated limit K_1/K_3 -> 0. Thus the global defect\ngeometry is controllable by tuning the relative splay to bend modulus."
    },
    {
        "anchor": "Light Microscopy at Maximal Precision: Microscopy is the workhorse of the physical and life sciences, producing\ncrisp images of everything from atoms to cells well beyond the capabilities of\nthe human eye. However, the analysis of these images is frequently little\nbetter than automated manual marking. Here, we revolutionize the analysis of\nmicroscopy images, extracting all the information theoretically contained in a\ncomplex microscope image. Using a generic, methodological approach, we extract\nthe information by fitting experimental images with a detailed optical model of\nthe microscope, a method we call Parameter Extraction from Reconstructing\nImages (PERI). As a proof of principle, we demonstrate this approach with a\nconfocal image of colloidal spheres, improving measurements of particle\npositions and radii by 100x over current methods and attaining the maximum\npossible accuracy. With this unprecedented resolution, we measure\nnanometer-scale colloidal interactions in dense suspensions solely with light\nmicroscopy, a previously impossible feat. Our approach is generic and\napplicable to imaging methods from brightfield to electron microscopy, where we\nexpect accuracies of 1 nm and 0.1 pm, respectively.",
        "positive": "Ion Induced Lamellar-Lamellar Phase Transition in Charged Surfactant\n  Systems: We propose a model for the liquid-liquid phase transition observed in osmotic\npressure measurements of certain charged lamellae-forming amphiphiles. The\nmodel free energy combines mean-field electrostatic and phenomenological\nnon-electrostatic interactions, while the number of dissociated counterions is\ntreated as a variable degree of freedom that is determined self-consistently.\nThe model, therefore, joins two well-known theories: the Poisson-Boltzmann\ntheory for ionic solutions between charged lamellae, and\nLangmuir-Frumkin-Davies adsorption isotherm modified to account for charged\nadsorbing species. Minimizing the appropriate free energy for each\ninterlamellar spacing, we find the ionic density profiles and the resulting\nosmotic pressure. While in the simple Poisson-Boltzmann theory the osmotic\npressure isotherms are always smooth, we observe a discontinuous liquid-liquid\nphase transition when Poisson-Boltzmann theory is self-consistently augmented\nby Langmuir-Frumkin-Davies adsorption. This phase transition depends on the\narea per amphiphilic headgroup, as well as on non-electrostatic interactions of\nthe counterions with the lamellae, and interactions between counterion-bound\nand counterion-dissociated surfactants. Coupling lateral phase transition in\nthe bilayer plane with electrostatic interactions in the bulk, our results\noffer a qualitative explanation for the existence of the phase-transition of\nDDABr (didodecyldimethylammonium bromide), but its apparent absence for the\nchloride and the iodide homologues. More quantitative comparisons with\nexperiment require better understanding of the microscopic basis of the\nphenomenological model parameters."
    },
    {
        "anchor": "Suppression of the Rayleigh-Plateau instability on a vertical fibre\n  coated with wormlike micelle solutions: We report on the Rayleigh-Plateau instability in films of giant micelles\nsolutions coating a vertical fibre. We observe that the dynamics of thin films\ncoating the fibre could be very different from the Newtonian or standard\nNon-Newtonian cases. By varying the concentration of the components of the\nsolutions and depending on the film thickness, we show for the first time that\nthe Rayleigh-Plateau instability can be stabilized using surfactant solutions.\nUsing global rheology and optical visualisations, we show that the development\nof shear-induced structures is required to stabilize the micellar film along\nthe fibre. Assuming that the viscoelastic properties of the shear-induced state\ncan be described by a simple model, we suggest that, in addition to the\npresence of shear-induced structures, the latter must have an elastic modulus\ngreater than a critical value evaluated from a linear stability analysis.\nFinally, our analysis provides a way of estimating the bulk elasticity of the\nshear-induced state.",
        "positive": "Competition and cooperation:aspects of dynamics in sandpiles: In this article, we review some of our approaches to granular dynamics, now\nwell known to consist of both fast and slow relaxational processes. In the\nfirst case, grains typically compete with each other, while in the second, they\ncooperate. A typical result of {\\it cooperation} is the formation of stable\nbridges, signatures of spatiotemporal inhomogeneities; we review their\ngeometrical characteristics and compare theoretical results with those of\nindependent simulations. {\\it Cooperative} excitations due to local density\nfluctuations are also responsible for relaxation at the angle of repose; the\n{\\it competition} between these fluctuations and external driving forces, can,\non the other hand, result in a (rare) collapse of the sandpile to the\nhorizontal. Both these features are present in a theory reviewed here. An arena\nwhere the effects of cooperation versus competition are felt most keenly is\ngranular compaction; we review here a random graph model, where three-spin\ninteractions are used to model compaction under tapping. The compaction curve\nshows distinct regions where 'fast' and 'slow' dynamics apply, separated by\nwhat we have called the {\\it single-particle relaxation threshold}. In the\nfinal section of this paper, we explore the effect of shape -- jagged vs.\nregular -- on the compaction of packings near their jamming limit. One of our\nmajor results is an entropic landscape that, while microscopically rough,\nmanifests {\\it Edwards' flatness} at a macroscopic level. Another major result\nis that of surface intermittency under low-intensity shaking."
    },
    {
        "anchor": "Inverse projection of axisymmetric orientation distributions: We show that the projection of an axisymmetric three-dimensional orientation\ndistribution to two dimensions can be cast into an Abel transform. Based on\nthis correspondence, we derive an exact integral inverse, which allows for the\nquantification of three-dimensional uniaxial alignment of rodlike units from\ntwo-dimensional sliced images, thus providing an alternative to X-ray or\ntomographic analysis. A matrix representation of the projection and its inverse\nis derived, providing a direct relationship between two- and three-dimensional\norder parameters for both polar and non-polar systems.",
        "positive": "Using Multiscale Molecular Dynamics Simulations to Obtain Insights into\n  Pore Forming Toxin Mechanisms: Pore forming toxins (PFTs) are virulent proteins released by several species,\nincluding many strains of bacteria, to attack and kill host cells. In this\narticle, we focus on the utility of molecular dynamics (MD) simulations and the\nmolecular insights gleaned from these techniques on the pore forming pathways\nof PFTs. In addition to all-atom simulations which are widely used, coarse\ngrained MARTINI models and structure based models have also been used to study\nPFTs. Here, the emphasis is on methods and techniques involved while setting\nup, monitoring, and evaluating properties from MD simulations of PFTs in a\nmembrane environment. We draw from several case studies to illustrate how MD\nsimulations have provided molecular insights into protein-protein and\nprotein-lipid interactions, lipid dynamics, conformational transitions and\nstructures of both the oligomeric intermediates and assembled pore structures."
    },
    {
        "anchor": "Scaling Theory of Polyelectrolyte Adsorption on Repulsive Charged\n  Surface: We studied polyelectrolyte adsorption on a repulsive charged surface by\nscaling analysis. At low ionic strength and low surface charge density in which\na single polyelectrolyte is able to be adsorbed onto the surface, different\nregimes in the phase diagram are identified. The possibility of multi-layer\nstructure formed by polyelectrolytes of like charge is also investigated.",
        "positive": "Bridging the Gap Between Collective Motility and Epithelial-Mesenchymal\n  Transitions through the Active Finite Voronoi Model: We introduce an active version of the recently proposed finite Voronoi model\nof epithelial tissue. The resultant Active Finite Voronoi (AFV) model enables\nthe study of both confluent and non-confluent geometries and transitions\nbetween them, in the presence of active cells. Our study identifies six\ndistinct phases, characterized by aggregation-segregation, dynamical\njamming-unjamming, and epithelial-mesenchymal transitions (EMT), thereby\nextending the behavior beyond that observed in previously studied vertex-based\nmodels. The AFV model with rich phase diagram provides a cohesive framework\nthat unifies the well-observed progression to collective motility via unjamming\nwith the intricate dynamics enabled by EMT. This approach should prove useful\nfor challenges in developmental biology systems as well as the complex context\nof cancer metastasis. The simulation code is also provided at\nhttps://github.com/jxhuangphys/Active_Finite_Voronoi_simulation."
    },
    {
        "anchor": "Saddle-splay screening and chiral symmetry breaking in toroidal nematics: We present a theoretical study of director fields in toroidal geometries with\ndegenerate planar boundary conditions. We find spontaneous chirality: despite\nthe achiral nature of nematics the director configuration show a handedness if\nthe toroid is thick enough. In the chiral state the director field displays a\ndouble twist, whereas in the achiral state there is only bend deformation. The\ncritical thickness increases as the difference between the twist and\nsaddle-splay moduli grows. A positive saddle-splay modulus prefers alignment\nalong the short circle of the bounding torus, and hence stimulates promotes a\nchiral configuration. The chiral-achiral transition mimics the order-disorder\ntransition of the mean-field Ising model. The role of the magnetisation in the\nIsing model is played by the degree of twist. The role of the temperature is\nplayed by the aspect ratio of the torus. Remarkably, an external field does not\nbreak the chiral symmetry explicitly, but shifts the transition. In the case of\ntoroidal cholesterics, we do find a preference for one chirality over the other\n-- the molecular chirality acts as a field in the Ising analogy.",
        "positive": "Optical transparency of mesoporous metals: We examine the optical properties of metals containing a periodic arrangement\nof nonoverlapping spherical mesopores, empty or filled with a dielectric\nmaterial. We show that a slab of such a porous metal transmits light over\nregions of frequency determined by the dielectric constant of the cavities and\nthe fractional volume occupied by them, with an efficiency which is many orders\nof magnitude higher than predicted by standard aperture theory. Also, the\nsystem absorbs light efficiently over the said regions of frequency unlike the\nhomogeneous metal."
    },
    {
        "anchor": "Direct measurements of hydrophobic slippage using double-focus\n  fluorescence cross-correlation: We report results of direct measurements of velocity profiles in a\nmicrochannel with hydrophobic and hydrophilic walls, using a new high precision\nmethod of double-focus spacial fluorescence cross-correlation under a confocal\nmicroscope. In the vicinity of both walls the measured velocity profiles do not\nturn to zero by giving a plateau of constant velocity. This apparent slip is\nproven to be due to a Taylor dispersion, an augmented by shear diffusion of\nnanotracers in the direction of flow. Comparing the velocity profiles near the\nhydrophobic and hydrophilic walls for various conditions shows that there is a\ntrue slip length due to hydrophobicity. This length, of the order of several\ntens of nanometers, is independent on electrolyte concentration and shear rate.",
        "positive": "Ordered ground state configurations of the asymmetric Wigner bilayer\n  system -- revisited: an unsupervised clustering algorithm analysis: We have re-analysed the rich plethora of ground state configurations of the\nasymmetric Wigner bilayer system that we had recently published in a related\ndiagram of states [M. Antlanger \\textit{et al.}, Phys. Rev. Lett. \\textbf{117},\n118002 (2016)], comprising roughly 60~000 state points in the phase space\nspanned by the distance between the plates and the charge asymmetry parameter\nof the system. In contrast to this preceding contribution where the\nclassification of the emerging structures was carried out ``by hand'', we have\nused this time machine learning concepts, notably based on a principal\ncomponent analysis and a $k$-means clustering approach: using a 30-dimensional\nfeature vector for each emerging structure (containing relevant information,\nsuch as the composition of the configuration as well as the most relevant order\nparameters) we were able to re-analyse these ground state configurations in a\nconsiderably more systematic and comprehensive manner than we could possibly do\nin the previously published classification scheme. Indeed we were now able to\nidentify new structures in previously unclassified regions of the parameter\nspace and could considerably refine the previous classification scheme,\nidentifying thereby a rich wealth of new emerging ground state configurations.\nThorough consistency checks confirm the validity of the newly defined diagram\nof states."
    },
    {
        "anchor": "Reconstructing Three-dimensional Helical Structure With an X-Ray Free\n  Electron Laser: Recovery of three-dimensional structure from single particle X-ray scattering\nof completely randomly oriented diffraction patterns as predicted few decades\nback has been real due to the advent of the new emerging X-ray Free Electron\nLaser (XFEL) technology. As the worlds first XFEL is in operation starting from\nJune 2009 at SLAC National Lab at Stanford, the very first few experiments\nbeing conducted on larger objects such as viruses. Many of the important\nstructures of nature such as helical viruses or deoxyribonucleic acids (DNA)\nconsist of helical repetition of biological subunits. Hence development of\nmethod for reconstructing helical structure from collected XFEL data has been a\ntop priority research. In this work we have developed a method for solving\nhelical structure such as TMV (tobacco mosaic virus) from a set of randomly\noriented simulated diffraction patterns exploiting symmetry and Fourier space\nconstraint of the diffraction volume.",
        "positive": "From hydrodynamic lubrication to many-body interactions in dense\n  suspensions of active swimmers: We study how hydrodynamic interactions affect the collective behaviour of\nactive particles suspended in a fluid at high concentrations, with particular\nattention to lubrication forces which appear when the particles are very close\nto one another. We compute exactly the limiting behaviour of the hydrodynamic\ninteractions between two spherical (circular) active swimmers in very close\nproximity to one another in the general setting in both three and (two)\ndimensions. Combining this with far-field interactions, we develop a novel\nnumerical scheme which allows us to study the collective behaviour of large\nnumbers of active particles with accurate hydrodynamic interactions when close\nto one another. We study active swimmers whose intrinsic flow fields are\ncharacterised by force dipoles and quadrupoles. Using this scheme, we are able\nto show that lubrication forces when the particles are very close to each other\ncan play as important a role as long-range hydrodynamic interactions in\ndetermining their many-body behaviour. We find that when the swimmer force\ndipole is large, finite clusters and open gel-like clusters appear rather than\ncomplete phase separation. This suppression is due to near-field lubrication\ninteractions. For swimmers with small force dipoles, we find surprisingly that\na globally polar ordered phase appears because near-field lubrication rather\nthan long-range hydrodnamics dominate the alignment mechanism. Polar order is\npresent for very large system sizes and is stable to fluctuations with a finite\nnoise amplitude. We explain the emergence of polar order using a minimal model\nin which only the leading rotational effect of the near-field interaction is\nincluded. These phenomena are also reproduced in two dimensions."
    },
    {
        "anchor": "Spatiotemporal patterning of extensile active stresses in\n  microtubule-based active fluids: Active stresses, which are collectively generated by the motion of\nenergy-consuming rod-like constituents, generate chaotic autonomous flows.\nControlling active stresses in space and time is an essential prerequisite for\ncontrolling the intrinsically chaotic dynamics of extensile active fluids. We\ndesign single-headed kinesin molecular motors that exhibit optically enhanced\nclustering, and thus enable precise and repeatable spatial and temporal control\nof extensile active stresses. Such motors enable rapid, reversible switching\nbetween flowing and quiescent states. In turn, spatio-temporal patterning of\nthe active stress controls the evolution of the ubiquitous bend-instability of\nextensile active fluids and determines its critical length dependence.\nCombining optically controlled clusters with conventional kinesin motors\nenables one-time switching from contractile to extensile active stresses. These\nresults open a path towards real-time control of the autonomous flows generated\nby active fluids.",
        "positive": "Rotational and translational diffusion of anisotropic gold nanoparticles\n  in liquid crystals controlled by varying surface anchoring: We study translational and rotational diffusion of anisotropic gold\nnanoparticles (NPs) dispersed in the bulk of a nematic liquid crystal fluid\nhost. Experimental data reveal strong anisotropy of translational diffusion\nwith respect to the uniform far-field director, which is dependent on shape and\nsurface functionalization of colloids as well as on their ground-state\nalignment. For example, elongated NPs aligned parallel to the far-field\ndirector translationally diffuse more rapidly along the director whereas\ndiffusion of NPs oriented normal to the director is faster in the direction\nperpendicular to it while they are also undergoing elasticity-constrained\nrotational diffusion. To understand physical origins of these rich diffusion\nproperties of anisotropic nanocolloids in uniaxially anisotropic nematic fluid\nmedia, we compare them to diffusion of prolate and oblate ellipsoidal particles\nin isotropic fluids as well as to diffusion of shape-isotropic particles in\nnematic fluids. We also show that surface functionalization of NPs with\nphotosensitive azobenzene groups allows for in situ control of their\ndiffusivity through trans-cis isomerization that changes surface anchoring."
    },
    {
        "anchor": "Lagrangian statistics of dense emulsions: The dynamics of dense stabilized emulsions presents a rich phenomenology\nincluding chaotic emulsification, non-Newtonian rheology and ageing dynamics at\nrest. Macroscopic rheology results from the complex droplet microdynamics and,\nin turn, droplet dynamics is influenced by macroscopic flows via the competing\naction of hydrodynamic and interfacial stresses, giving rise to a complex\ntangle of elastoplastic effects, diffusion, breakups and coalescence events.\nThis tight multiscale coupling, together with the daunting challenge of\nexperimentally investigating droplets under flow, hindered the understanding of\ndense emulsions dynamics. We present results from 3D numerical simulations of\ndense stabilised emulsions, resolving the shape and dynamics of individual\ndroplets, along with the macroscopic flows. We investigate droplet dispersion\nstatistics, measuring probability density functions (PDF) of droplet\ndisplacements and velocities, changing the concentration, in the stirred and\nageing regimes. We provide the first measurements ever, in concentrated\nemulsions, of the relative droplet-droplet separations PDF and of the droplet\nacceleration PDF, which becomes strongly non-Gaussian as the volume fraction is\nincreased above the jamming point. Cooperative effects, arising when droplets\nare in contact, are argued to be responsible of the anomalous superdiffusive\nbehaviour of the mean square displacement and of the pair separation at long\ntimes, in both the stirred and in the ageing regimes. This superdiffusive\nbehaviour is reflected in a non-Gaussian pair separation PDF, whose analytical\nform is investigated, in the ageing regime, by means of theoretical arguments.\nThis work paves the way to developing a connection between Lagrangian dynamics\nand rheology in dense stabilised emulsions.",
        "positive": "Sub-Piconewton Force Detection using Micron-Size Wire Deflections: The mechanical properties of nanostructured wires obtained by co-assembly of\niron oxide particles are studied. The intrinsic magnetic properties of the\nwires are used to induce and quantify the bending of the one-dimensional\nobjects. From the relationship between the deflection and the magnitude of the\nmagnetic field, the elastic rigidity and Young modulus of the wires are\ndetermined. Young moduli in the megapascal range are obtained and are\nconsistent with sub-piconewton force detection."
    },
    {
        "anchor": "Solution landscapes of ferronematics in microfluidic channels: We investigate solution landscapes for ferronematics i.e., a dilute\nsuspension of magnetic nano-particles in a nematic liquid crystal host, in a\nreduced one-dimensional setting relevant for microfluidic problems. Solution\nlandscapes show how critical points of an energy functional connect to one\nanother on the energy landscape, hence revealing potential mechanism by which\nmultistable systems may switch between different stable states. By varying\nmodel parameters, we show that increasing domain size and increasing\nnemato-magnetic coupling have the same impact on the solution landscape, in\nthat both result in new emergent solutions. Hence, this presents multiple\navenues for experimental realisation of multistable ferronematic systems with\ndesired properties. We also show the prevalence, and therefore importance, of\nferronematic polydomains, which present themselves as what we call order\nreconstruction (OR) solutions. These ferronematic OR solutions possess a great\ndeal of complexity in terms of the location and multiplicity of domain walls,\nand also play a key role in the connectivity of stable states for the solution\nlandscapes considered.",
        "positive": "Fore-aft asymmetric flocking: We show that fore-aft asymmetry, a generic feature of living organisms and\nsome active matter systems, can have a strong influence on the collective\nproperties of even the simplest flocking models. Specifically, an arbitrarily\nweak asymmetry favoring front neighbors changes qualitatively the phase diagram\nof the Vicsek model. A region where many sharp traveling band solutions coexist\nis present at low noise strength, below the Toner-Tu liquid, at odds with the\nphase-separation scenario well describing the usual isotropic model. Inside\nthis region, a `banded liquid' phase with algebraic density distribution\ncoexists with band solutions. Linear stability analysis at the hydrodynamic\nlevel suggests that these results are generic and not specific to the Vicsek\nmodel."
    },
    {
        "anchor": "Microscopic Theory for the Dynamics of Unentangled and Entangled Polymer\n  Melts: The Langevin Equation for cooperative dynamics represents the dynamics of\npolymer melts with chains of increasing degree of polymerization, covering the\nfull range of behavior from the unentangled to the entangled regime. This\nequation describes the motion of a group of interpenetrating polymers that are\ninteracting through an effective potential resulting from the many-body\ncoupling of the inter polymer potential inside the macromolecular liquid. The\nconfinement of the dynamics due to the presence of entanglements is accounted\nfor by an effective inter-monomer potential which is zero until the distance\nbetween two monomers belonging to different chains reaches a characteristic\nvalue, d. At that distance a constraint is applied through an effective\nhard-core repulsion that represents the effect of entanglements in the slowing\ndown of the relative diffusion of the monomers. As the time evolves the\nconstraint relaxes due to the chain interdiffusion. The same potential acts on\nboth unentangled and entangled polymer chains, but short chains are not\naffected as they relax faster than they experience the presence of the\npotential. The comparison with Neutron Spin Echo experiments of polyethylene\nmelts shows quantitative agreement of the theory with the time dependent\nincoherent scattering function for a variety of samples in both the unentangled\nand the entangled regimes.",
        "positive": "Origin of ultrastability in vapor-deposited glasses: Glass films created by vapor-depositing molecules onto a substrate can\nexhibit properties similar to those of ordinary glasses aged for thousands of\nyears. It is believed that enhanced surface mobility is the mechanism that\nallows vapor deposition to create such exceptional glasses, but it is unclear\nhow this effect is related to the final state of the film. Here we use\nmolecular dynamics simulations to model vapor deposition and an efficient Monte\nCarlo algorithm to determine the deposition rate needed to create ultra-stable\nglassy films. We obtain a scaling relation that quantitatively captures the\nefficiency gain of vapor deposition over bulk annealing, and demonstrates that\nsurface relaxation plays the same role in the formation of vapor-deposited\nglasses as bulk relaxation does in ordinary glass formation."
    },
    {
        "anchor": "Extended event driven molecular dynamics for simulating dense granular\n  matter: A new numerical method is presented to efficiently simulate the inelastic\nhard sphere (IHS) model for granular media, when fluid and frozen regions\ncoexist in the presence of gravity. The IHS model is extended by allowing\nparticles to change their dynamics into either a frozen state or back to the\nnormal collisional state, while computing the dynamics only for the particles\nin the normal state. Careful criteria, local in time and space, are designed\nsuch that particles become frozen only at mechanically stable positions. The\nhomogeneous deposition over a static surface and the dynamics of a rotating\ndrum are studied as test cases. The simulations agree with previous\nexperimental results. The model is much more efficient than the usual event\ndriven method and allows to overcome some of the difficulties of the standard\nIHS model, such as the existence of a static limit.",
        "positive": "Undulation instabilities in cholesteric liquid crystals induced by\n  anchoring transitions: Cholesteric liquid crystals (CLCs) have a characteristic length scale given\nby the pitch of the twisted stacking of their constituent rod-like molecules.\nUnder homeotropic anchoring conditions where the molecules prefer to orient\nperpendicular to an interface, cholesteric interfaces exhibit striped phases\nwith stripe widths commensurate with the pitch. Conversely, planar anchoring\nconditions have the molecules remain in the plane of the interface so that the\nCLC twists perpendicular to it. Recent work [L. Tran et al. Phys. Rev. X 7,\n041029 (2017)] shows that varying the anchoring conditions dramatically\nrearranges the CLC stripe pattern, exchanging defects in the stripe pattern\nwith defects in the molecular orientation of the liquid crystal molecules. We\nshow with experiments and numerical simulations that the CLC stripes also\nundergo an undulation instability when we transition from homeotropic to planar\nanchoring conditions and vice versa. The undulation can be interpreted as a\ntransient relaxation of the CLC resulting from a strain in the cholesteric\nlayers due to a tilting pitch axis, with properties analogous to the classic\nHelfrich-Hurault instability. We focus on CLC shells in particular and show\nthat the spherical topology of the shell also plays an important role in\nshaping the undulations."
    },
    {
        "anchor": "Local phase transitions in driven colloidal suspensions: Using dynamical density functional theory and Brownian dynamics simulations\nwe investigate the influence of a driven tracer particle on the density\ndistribution of a colloidal suspension at a thermodynamic statepoint close to\nthe liquid side of the binodal. In bulk systems we find that a localized region\nof the colloid-poor phase, a 'cavitation bubble', forms behind the moving\ntracer. The extent of the cavitation bubble is investigated as a function of\nboth the size and velocity of the tracer. The addition of a confining boundary\nenables us to investigate the interaction between the local phase instability\nat the substrate and that at the particle surface. When both the substrate and\ntracer interact repulsively with the colloids we observe the formation of a\ncolloid-poor bridge between the substrate and the tracer. When a shear flow is\napplied parallel to the substrate the bridge becomes distorted and, at\nsufficiently high shear-rates, disconnects from the substrate to form a\ncavitation bubble.",
        "positive": "Toward a unified description of the electrostatic assembly of microgels\n  and nanoparticles: The combination of soft responsive particles, such as microgels, with\nnanoparticles (NPs) yields highly versatile complexes of great potential for\napplications, from ad-hoc plasmonic sensors to controlled protocols for loading\nand release. However, the assembly process between these microscale networks\nand the co-dispersed nano-objects has not been investigated so far at the\nmicroscopic level, preempting the possibility of designing such hybrid\ncomplexes a priori. In this work, we combine state-of-the-art numerical\nsimulations with experiments, to elucidate the fundamental mechanisms taking\nplace when microgels-NPs assembly is controlled by electrostatic interactions.\nWe find a general behavior where, by increasing the number of interacting NPs,\nthe microgel deswells up to a minimum size, after which a plateau behavior\noccurs. This occurs either when NPs are mainly adsorbed to the microgel corona\nvia the folding of the more external chains, or when NPs penetrate inside the\nmicrogel, thereby inducing a collective reorganization of the polymer network.\nBy varying microgel properties, such as fraction of crosslinkers or charge, as\nwell as NPs size and charge, we further show that the microgel deswelling\ncurves can be rescaled onto a single master curve, for both experiments and\nsimulations, demonstrating that the process is entirely controlled by the\ncharge of the whole microgel-NPs complex. Our results thus have a direct\nrelevance in fundamental materials science and offer novel tools to tailor the\nnanofabrication of hybrid devices of technological interest."
    },
    {
        "anchor": "Particle-stabilized oscillating diver: a self-assembled responsive\n  capsule: We report the experimental discovery of a self-assembled capsule, with\ndensity set by interfacial glass beads and an internal bubble, that\nautomatically performs regular oscillations up and down a vial in response to a\ntemperature gradient. Similar composites featuring interfacial particles and\nmultiple internal compartments could be the solution to a variety of\napplication challenges.",
        "positive": "Friction of viscoelastic elastomers with rough surfaces under torsional\n  contact conditions: Frictional properties of contacts between a smooth viscoelastic rubber and\nrigid surfaces are investigated using a torsional contact configuration where a\nglass lens is continuously rotated on the rubber surface. From the inversion of\nthe displacement field measured at the surface of the rubber, spatially\nresolved values of the steady state frictional shear stress are determined\nwithin the non homogeneous pressure and velocity fields of the contact. For\ncontacts with a smooth lens, a velocity dependent but pressure independent\nlocal shear stress is retrieved from the inversion. On the other hand, the\nlocal shear stress is found to depend both on velocity and applied contact\npressure when a randomly rough (sand blasted) glass lens is rubbed against the\nrubber surface. As a result of changes in the density of micro-asperity\ncontacts, the amount of light transmitted by the transparent multi-contact\ninterface is observed to vary locally as a function of both contact pressure\nand sliding velocity. Under the assumption that the intensity of light\ntransmitted by the rough interface is proportional to the proportion of area\ninto contact, it is found that the local frictional stress can be expressed\nexperimentally as the product of a purely velocity dependent term, $k(v)$, by a\nterm representing the pressure and velocity dependence of the actual contact\narea, $A/A_0$. A comparison between $k(v)$ and the frictional shear stress of\nsmooth contacts suggests that nanometer scale dissipative processes occurring\nat the interface predominate over viscoelastic dissipation at micro-asperity\nscale."
    },
    {
        "anchor": "A polarizable ion model for the structure of molten AgI: The results are reported of the molecular dynamics simulations of the\ncoherent static structure factor of molten AgI at 923 K using a polarizable ion\nmodel. This model is based on a rigid ion potential, to which the many body\ninteractions due to the anions induced polarization are added. The calculated\nstructure factor is in better agreement with recent neutron diffraction data\nthan that obtained by using simple rigid ion pair potentials. The\nVoronoi-Delaunay method has been applied to study the relationship between\nvoids in the spatial distribution of cations and the prepeak of the structure\nfactor.",
        "positive": "Dynamics of vitrimers: defects as a highway to stress relaxation: We propose a coarse-grained model to investigate stress relaxation in\nstar-polymer networks induced by dynamic bond exchange processes. We show how\nthe swapping mechanism, once activated, allows the network to reconfigure,\nexploring distinct topological configurations, all of them characterised by\ncomplete extent of reaction. Our results reveal the important role played by\ntopological defects in mediating the exchange reaction and speeding up stress\nrelaxation. The model provides a representation of the dynamics in vitrimers, a\nnew class of polymers characterized by bond swap mechanisms which preserve the\ntotal number of bonds, as well as in other bond-exchange materials."
    },
    {
        "anchor": "Multi-scale Times and Modes of Fast and Slow Relaxation in Solutions\n  with Coexisting Spherical and Cylindrical Micelles according to the\n  Difference Becker-Doering Kinetic Equations: The eigenvalues and eigenvectors of the matrix of coefficients of the\nlinearized kinetic equations applied to aggregation in surfactant solution\ndetermine the full spectrum of characteristic times and specific modes of\nmicellar relaxation. The dependence of these relaxation times and modes on the\ntotal surfactant concentration has been analyzed for concentrations in the\nvicinity and well above the second critical micelle concentration (cmc2) for\nsystems with coexisting spherical and cylindrical micelles. The analysis has\nbeen done on the basis of a discrete form of the Becker-Doering kinetic\nequations employing the Smoluchowsky diffusion model for the attachment rates\nof surfactant monomers to surfactant aggregates with matching the rates for\nspherical aggregates and the rates for large cylindrical micelles. The\nequilibrium distribution of surfactant aggregates in solution has been modeled\nas having one maximum for monomers, another maximum for spherical micelles and\nwide slowly descending branch for cylindrical micelles. The results of\ncomputations have been compared with the analytical ones known in the limiting\ncases from solutions of the continuous Becker-Doering kinetic equation. They\ndemonstrated a fair agreement even in the vicinity of the cmc2 where the\nanalytical theory looses formally its applicability.",
        "positive": "Measurement of the angular momentum of a rotating Bose-Einstein\n  condensate: We study the quadrupole oscillation of a Bose-Einstein condensate of\n$^{87}$Rb atoms confined in an axisymmetric magnetic trap, after it has been\nstirred by an auxiliary laser beam. The stirring may lead to the nucleation of\none or more vortices, whose presence is revealed unambiguously by the\nprecession of the axes of the quadrupolar mode. For a stirring frequency\n$\\Omega$ below the single vortex nucleation threshold $\\Omega_c$, no measurable\nprecession occurs. Just above $\\Omega_c$, the angular momentum deduced from the\nprecession is $\\sim \\hbar$. For stirring frequencies above $\\Omega_c$ the\nangular momentum is a smooth and increasing function of $\\Omega$, until an\nangular frequency $\\Omega_c'$ is reached at which the vortex lattice disappears\nand the precession stops."
    },
    {
        "anchor": "Levy Flights and Earthquakes: Levy flights representation is proposed to describe earthquake\ncharacteristics like the distribution of waiting times and position of\nhypocenters in a seismic region. Over 7500 microearthquakes and earthquakes\nfrom 1985 to 1994 were analyzed to test that its spatial and temporal\ndistributions are such that can be described by a Levy flight with anomalous\ndiffusion (in this case in a subdiffusive regime). Earthquake behavior is well\ndescribed through Levy flights and Levy distribution functions such as results\nshow.",
        "positive": "Dynamics of two trapped Brownian particles: shear-induced\n  cross-correlations: The dynamics of two Brownian particles trapped by two neighboring harmonic\npotentials in a linear shear flow is investigated. The positional correlation\nfunctions in this system are calculated analytically and analyzed as a function\nof the shear rate and the trap distance. Shear-induced cross-correlations\nbetween particle fluctuations along orthogonal directions in the shear plane\nare found. They are linear in the shear rate, asymmetric in time, and occur for\none particle as well as between both particles. Moreover, the shear rate enters\nas a quadratic correction to the well-known correlations of random\ndisplacements along parallel spatial directions. The correlation functions\ndepend on the orientation of the connection vector between the potential minima\nwith respect to the flow direction. As a consequence, the inter-particle\ncross-correlations between orthogonal fluctuations can have zero, one or two\nlocal extrema as a function of time. Possible experiments for detecting these\npredicted correlations are described."
    },
    {
        "anchor": "Geometry and dynamics of lipid membranes: The Scriven--Love number: The equations governing lipid membrane dynamics in planar, spherical, and\ncylindrical geometries are presented here. Unperturbed and first-order\nperturbed equations are determined and non-dimensionalized. In membrane systems\nwith a nonzero base flow, perturbed in-plane and out-of-plane quantities are\nfound to vary over different length scales. A new dimensionless number, named\nthe Scriven--Love number, and the well-known F\\\"oppl--von K\\'arm\\'an number\nresult from a scaling analysis. The Scriven--Love number compares out-of-plane\nforces arising from the in-plane, intramembrane viscous stresses to the\nfamiliar elastic bending forces, while the F\\\"oppl--von K\\'arm\\'an number\ncompares tension to bending forces. Both numbers are calculated in past\nexperimental works, and span a wide range of values in various biological\nprocesses across different geometries. In situations with large Scriven--Love\nand F\\\"oppl--von K\\'arm\\'an numbers, the dynamical response of a perturbed\nmembrane is dominated by out-of-plane viscous and surface tension forces---with\nbending forces playing a negligible role. Calculations of non-negligible\nScriven--Love numbers in various biological processes and in vitro experiments\nshow in-plane intramembrane viscous flows cannot generally be ignored when\nanalyzing lipid membrane behavior.",
        "positive": "Equilibrium of Free Surfaces and Nanoparticles in Self-Consistent Field\n  Theory of Block Copolymers: This work presents a general and unified theory describing block copolymer\nself-assembly in the presence of free surfaces and nanoparticles in the context\nof Self-Consistent Filed Theory. Specifically, the derived theory applies to\nfree and tethered polymer chains, nanoparticles of any shape, arbitrary\nnon-uniform surface energies and grafting densities, and takes into account a\npossible formation of triple-junction points (e.g., polymer-air-substrate). One\nof the main ingredients of the proposed theory is a simple procedure for a\nconsistent imposition of boundary conditions on surfaces with non-zero surface\nenergies and/or non-zero grafting densities that results in singularity-free\npressure-like fields, which is crucial for the calculation of forces. The\ngenerality of the theory is demonstrated using several representative examples\nsuch as the meniscus formation in the graphoepitaxy and the co-assembly of\n\"polarized\" nano-rods and diblock copolymer melts."
    },
    {
        "anchor": "The effect of cryogenic thermal cycling on aging, rejuvenation, and\n  mechanical properties of metallic glasses: The structural relaxation, potential energy states, and mechanical properties\nof a model glass subjected to thermal cycling are investigated using molecular\ndynamics simulations. We study a non-additive binary mixture which is annealed\nwith different cooling rates from the liquid phase to a low temperature well\nbelow the glass transition. The thermal treatment is applied by repeatedly\nheating and cooling the system at constant pressure, thus temporarily inducing\ninternal stresses upon thermal expansion. We find that poorly annealed glasses\nare relocated to progressively lower levels of potential energy over\nconsecutive cycles, whereas well annealed glasses can be rejuvenated at\nsufficiently large amplitudes of thermal cycling. Moreover, the lowest levels\nof potential energy after one hundred cycles are detected at a certain\ntemperature amplitude for all cooling rates. The structural transition to\ndifferent energy states is accompanied by collective nonaffine displacements of\natoms that are organized into clusters, whose typical size becomes larger with\nincreasing cooling rate or temperature amplitude. We show that the elastic\nmodulus and the peak value of the stress overshoot exhibit distinct maxima at\nthe cycling amplitude, which corresponds to the minimum of the potential\nenergy. The simulation results indicate that the yielding peak as a function of\nthe cycling amplitude for quickly annealed glasses represents a lower bound for\nthe maximum stress in glasses prepared with lower cooling rates.",
        "positive": "A Bayesian analysis of neutron spin echo data on polymer coated gold\n  nanoparticles in aqueous solutions: We present a neutron spin echo study (NSE) of the nanosecond dynamics of\npolyethylene glycol (PEG) functionalised nanosized gold particles dissolved in\nD$_2$O at two temperatures and two different PEG molecular weights. The\nanalysis of the NSE data was performed by applying a Bayesian approach to the\ndescription of time correlation function decays in terms of exponential terms,\nrecently proved to be theoretically rigorous. This approach, which addresses in\na direct way the fundamental issue of model choice in any dynamical analysis,\nprovides here a guide to the most statistically supported way to follow the\ndecay of the Intermediate Scattering Functions I(Q, t) by basing on statistical\ngrounds the choice of the number of terms required for the description of the\nnanosecond dynamics of the studied systems. Then, the presented analysis avoids\nfrom the start resorting to a pre-selected framework and can be considered as\nmodel free. By comparing the results of PEG coated nanoparticles with those\nobtained in PEG2000 solutions, we were able to disentangle the translational\ndiffusion of the nanoparticles from the internal dynamics of the polymer\ngrafted to them, and to show that the polymer corona relaxation follows a pure\nexponential decay in agreement with the behavior predicted by coarse grained\nmolecular dynamics simulations and theoretical models. This methodology has one\nfurther advantage: in the presence of a complex dynamical scenario I(Q,t) is\noften described in terms of the Kohlrausch-Williams-Watts function that can\nimplicitly represent a distribution of relaxation times. By choosing to\ndescribe the I(Q,t) as a sum of exponential functions and with the support of\nthe Bayesian approach, we can explicitly determine when a finer-structure\nanalysis of the dynamical complexity of the system exists according to the\navailable data without the risk of overparametrisation."
    },
    {
        "anchor": "Electro-osmosis in nematic liquid crystals: We derive a mathematical model of a nematic electrolyte based on a\nvariational formulation of nematodynamics. Extending our previous work, we\nconsider a general setup which incorporates dielectric anisotropy of the\nliquid-crystalline matrix and the full set of nematic viscosities. We verify\nthe model by comparing its predictions to the results of the experiments on the\nsubstrate-controlled liquid-crystal-enabled electrokinetics. In the experiments\na nematic liquid crystal confined to a thin planar cell with surface-patterned\nanchoring conditions exhibit electro-osmotic flows along the \"guiding rails\"\nimposed by the spatially varying director.",
        "positive": "Modeling truncated hemoglobin vibrational dynamics: We present a study on the near equilibrium dynamics of two small proteins in\nthe family of truncated hemoglobins, developed under the framework of a\nGaussian network approach. Effective beta carbon atoms are taken into account\nbesides C-alphas for all residues but glycines in the coarse-graining\nprocedure, without leading to an increase in the degrees of freedom\n(betaGaussian Model). Normalized covariance matrix and deformation along\nslowest modes with collective character are analyzed, pointing out\nanti-correlations between functionally relevant sites for the proteins under\nstudy. In particular we underline the functional motions of an extended\ntunnel-cavity system running inside the protein matrix, which provide a pathway\nfor small ligands binding with the iron in the heme group. We give a rough\nestimate of the order of magnitude of the relaxation times of the slowest two\noverdamped modes and compare results with previous studies on globins."
    },
    {
        "anchor": "Biomimetic non-ergodic aging by dynamic-to-covalent transitions in\n  physical hydrogels: Hydrogels are soft materials engineered to suit a multitude of applications\nthat exploit their tunable mechanochemical properties. Dynamic hydrogels\nemploying noncovalent, physically crosslinked networks dominated by either\nenthalpic or entropic interactions enable unique rheological and\nstimuli-responsive characteristics. In contrast to enthalpy-driven interactions\nthat soften with increasing temperature, entropic interactions result in\nlargely temperature-independent mechanical properties. By engineering\ninterfacial polymer-particle interactions, we can induce a dynamic-to-covalent\ntransition in entropic hydrogels that leads to biomimetic non-ergodic aging in\nthe microstructure without altering the network mesh size. This transition is\ntuned by varying temperature and formulation conditions such as $p$H, which\nallows for multivalent tunability in properties. These hydrogels can thus be\ndesigned to exhibit either temperature-independent metastable dynamic\ncrosslinking or time-dependent stiffening based on formulation and storage\nconditions, all while maintaining strucutural features critical for controlling\nmass transport, akin to many biological tissues. Such robust materials with\nversatile and adaptable properties can be utilized in applications such as\nwildfire suppression, surgical adhesives, and depot-forming injectable drug\ndelivery systems.",
        "positive": "Charge Effects and Nanoparticle Pattern Formation in Electrohydrodynamic\n  NanoDrip Printing of Colloids: Advancing open atmosphere printing technologies to produce features in the\nnanoscale range has important and broad applications ranging from electronics,\nto photonics, plasmonics and biology. Recently an electrohydrodynamic printing\nregime has been demonstrated in a rapid dripping mode (termed NanoDrip), where\nthe ejected colloidal droplets from nozzles of diameters of O(1 {\\mu}m) can\ncontrollably reach sizes an order of magnitude smaller than the nozzle and can\ngenerate planar and out-of-plane structures of similar sizes. Despite\ndemonstrated capabilities, our fundamental understanding of important aspects\nof the physics of NanoDrip printing needs further improvement. Here we address\nthe topics of charge content and transport in NanoDrip printing. We employ\nquantum dot and gold nanoparticle dispersions in combination with a specially\ndesigned, auxiliary, asymmetric electric field, targeting the understanding of\ncharge locality (particles vs. solvent) and particle distribution in the\ndeposits as indicated by the dried nanoparticle patterns (footprints) on the\nsubstrate. We show that droplets of alternating charge can be spatially\nseparated when applying an ac field to the nozzle. The nanoparticles within a\ndroplet are distributed asymmetrically under the influence of the auxiliary\nlateral electric field, indicating that they are the main carriers. We also\nshow that the ligand length of the nanoparticles in the colloid affects their\nmobility after deposition (in the sessile droplet state)."
    },
    {
        "anchor": "Experimental determination of the glass transition temperature in a very\n  narrow temperature range by Temperature Modulated Optical Refractometry: Latest since the landmark studies of Kovacs and co-workers on the glass\ntransition of polymers, it is clear that thermally induced volume changes are\nof central importance for the understanding of the nature of the glass\ntransition. Due to the kinetic background of the canonical (thermal) glass\ntransition, it does not seem possible to derive a well-defined glass transition\ntemperature T_g based on susceptibilities such as the thermal volume expansion\ncoefficient, \\beta(T), being strongly coupled to the glass transition process.\nTherefore, in practice, T_g is for example defined via the inflection point of\nthe step-like \\beta(T) curve. In this publication, we propose to use a\nthermo-optical feature, preceding the glass transition in the high-temperature\nphase, to determine the glass transition temperature T_g of a model polymer in\na rather narrow temperature interval.",
        "positive": "Dielectric Spectroscopy and Ultrasonic Study of Propylene Carbonate\n  under Ultra-high Pressures: We present the high pressure dielectric spectroscopy (up to 4.2 GPa) and\nultrasonic study (up to 1.7 GPa) of liquid and glassy propylene carbonate (PC).\nBoth of the methods provide complementary pictures of the glass transition in\nPC under pressure. No other relaxation processes except $\\alpha$-relaxation\nhave been found in the studied pressure interval. The propylene carbonate\nliquid is a glassformer where simple relaxation and the absence of\n$\\beta$-relaxation are registered in the record-breaking ranges of pressures\nand densities. The equation of state of liquid PC was extended up to 1 GPa from\nultrasonic measurements of bulk modulus and is in good accordance with the\nprevious equations developed from volumetric data. We measured the bulk and\nshear moduli and Poisson's ratio of glassy PC up to 1.7 GPa. Many relaxation\nand elastic properties of PC can be qualitatively described by the soft-sphere\nor Lennard-Jones model. However, for the quantitative description of entire set\nof the experimental data, these models are insufficient. Moreover, the Poisson\ncoefficient value for glassy PC indicates a significant contribution of\nnon-central forces to the intermolecular potential. The well-known correlation\nbetween Poisson's ratio and fragility index (obtained from dielectric\nrelaxation) is confirmed for PC at ambient pressure, but it is violated with\npressure increase. This indicates that different features of the potential\nenergy landscape are responsible for the evolution of dielectric response and\nelasticity with pressure increase."
    },
    {
        "anchor": "An Irreversible Synthetic Route to an Ultra-Strong Two-Dimensional\n  Polymer: Polymers that extend covalently in two dimensions have attracted recent\nattention as a means of combining the mechanical strength and in-plane energy\nconduction of conventional two-dimensional (2D) materials with the low\ndensities, synthetic processability, and organic composition of their\none-dimensional counterparts. Efforts to date have proven successful in forms\nthat do not allow full realization of these properties, such as polymerization\nat flat interfaces or fixation of monomers in immobilized lattices. A\nfrequently employed synthetic approach is to introduce microscopic\nreversibility, at the cost of bond stability, to achieve 2D crystals after\nextensive error correction. Herein we demonstrate a synthetic route to 2D\nirreversible polycondensation directly in the solution phase, resulting in\ncovalently bonded 2D polymer platelets that are chemically stable and highly\nprocessable. Further fabrication offers highly oriented, free-standing films\nwhich exhibit exceptional 2D elastic modulus and yield strength at 50.9 +- 15.0\nGPa and 0.976 +- 0.113 GPa, respectively. Platelet alignment is evidenced by\npolarized photoluminescence centered at 580 and 680 nm from different dipole\ntransitions. This new synthetic route provides opportunities for 2D polymers in\napplications ranging from composite structures to molecular sieving membranes.",
        "positive": "Hydrodynamic modeling of granular flows in a modified Couette cell: We present simulations of granular flows in a modified Couette cell, using a\ncontinuum model recently proposed for dense granular flows. Based on a friction\ncoefficient, which depends on an inertial number, the model captures the\npositions of the wide shear bands. We show that a smooth transition in\nvelocity-profile shape occurs when increasing the height of the granular\nmaterial, leading to a differential rotation of the central part close to the\nsurface. The numerical predictions are in qualitative agreement with previous\nexperimental results. The model provides predictions for the increase of the\nshear bands width when increasing the rotation rate."
    },
    {
        "anchor": "Characterization and control of phase fluctuations in elongated\n  Bose-Einstein condensates: Quasi one dimensional Bose-Einstein condensates (BECs) in elongated traps\nexhibit significant phase fluctuations even at very low temperatures. We\npresent recent experimental results on the dynamic transformation of phase\nfluctuations into density modulations during time-of-flight and show the\nexcellent quantitative agreement with the theoretical prediction. In addition\nwe confirm that under our experimental conditions, in the magnetic trap density\nmodulations are strongly suppressed even when the phase fluctuates. The paper\nalso discusses our theoretical results on control of the condensate phase by\nemploying a time-dependent perturbation. Our results set important limitations\non future applications of BEC in precision atom interferometry and atom optics,\nbut at the same time suggest pathways to overcome these limitations.",
        "positive": "Gas-solid coexistence of adhesive spheres: In this note we investigate using basic free energy considerations the\nlocation of the gas-liquid critical point with respect to solidification for\nnarrow attractive interactions down to the Baxter limit. Possible experimental\nand simulation realizations leading to a stable critical point are briefly\ndiscussed."
    },
    {
        "anchor": "Self-assembly of binary solutions to complex structures: Self-assembly in natural and synthetic molecular systems can create complex\naggregates or materials whose properties and functionality rises from their\ninternal structure and molecular arrangement. The key microscopic features that\ncontrol such assemblies remain poorly understood, nevertheless. Using classical\ndensity functional theory we demonstrate how the intrinsic length scales and\ntheir interplay in terms of interspecies molecular interactions can be used to\ntune soft matter self-assembly. We apply our strategy to two different soft\nbinary mixtures to create guidelines for tuning intermolecular interactions\nthat lead to transitions from fully miscible, liquid-like uniform state to\nformation of simple and core-shell aggregates, and mixed aggregate structures.\nFurthermore, we demonstrate how the interspecies interactions and system\ncomposition can be used to control concentration gradients of component species\nwithin these assemblies. The insight generated by this work contributes towards\nunderstanding and controlling soft multi-component self-assembly systems.\nAdditionally, our results aid in understanding complex biological assemblies\nand their function and provide tools to engineer molecular interactions in\norder to control polymeric and protein-based materials, pharmaceutical\nformulations, and nanoparticle assemblies.",
        "positive": "Torque determination on DNA with magnetic tweezers: We deduced the torque applied on a single stretched and twisted DNA by\nintegrating with respect to force the change in the molecule's extension as it\nis coiled. While consistent with previous direct measurements of the torque at\nhigh forces (F>1 pN) this method, which is simple and does not require a\nsophisticated set-up, allows for lower force estimates. We used this approach\nto deduce the effective torsional modulus of DNA, which decreases with force\nand to estimate the buckling torque of DNA as a function of force in various\nsalt conditions."
    },
    {
        "anchor": "Dynamical Clustering Interrupts Motility Induced Phase Separation in\n  Chiral Active Brownian Particles: One of the most intriguing phenomena in active matter has been the gas-liquid\nlike motility induced phase separation (MIPS) observed in repulsive active\nparticles. However, experimentally no particle can be a perfect sphere, and the\nasymmetric shape, mass distribution or catalysis coating can induce an active\ntorque on the particle, which makes it a chiral active particle. Here using\ncomputer simulations and dynamic mean-field theory, we demonstrate that the\nlarge enough torque of circle active Brownian particles (cABPs) in two\ndimensions generates a dynamical clustering state interrupting the conventional\nMIPS. Multiple clusters arise from the combination of the conventional MIPS\ncohesion, and the circulating current caused disintegration. The non-vanishing\ncurrent in non-equilibrium steady states microscopically originates from the\nmotility ``relieved'' by automatic rotation, which breaks the detailed balance\nat the continuum level. This suggests that no equilibrium-like phase separation\ntheory can be constructed for chiral active colloids even with tiny active\ntorque, in which no visible collective motion exists. This mechanism also sheds\nlight on the understanding of dynamic clusters observed in a variety of active\nmatter systems.",
        "positive": "Defects in Crystals of Soft Colloidal Particles: In this paper we use computer simulations to examine point defects in systems\nof \"soft\" colloidal particles including Hertzian spheres, and star polymers. We\nuse Monte Carlo simulations to determine the deformation of the different\ncrystals associated with vacancies and interstitials and use thermodynamic\nintegration to predict the equilibrium concentrations of such defects. We find\nthat the nature of the lattice distortion is mainly determined by the crystal\nstructure and not by the specifics of the interaction potential. We can\ndistinguish one-, two-, and three-dimensional lattice distortions and find that\nthe range of the distortion generally depends on the dimensionality. We find\nthat in both model systems the deformation of the body-centered cubic (BCC)\ncrystal caused by an interstitial is one-dimensional and we show that its\nstructure is well described as a crowdion. Similarly, we show that the\none-dimensional deformation of the hexagonal (H) crystal of Hertzian spheres\ncaused by a vacancy can be characterized as a voidion. Interestingly, with the\nexception of the FCC crystal in the Hertzian sphere model, in all cases we find\nthat the interstitial concentration is higher than the vacancy concentration.\nMost noteworthy, the concentration of interstitials in the BCC crystals can\nreach up to 1%."
    },
    {
        "anchor": "Great enhancement of mechanical features in PLA based composites\n  containing aligned few layer graphene (FLG), the effect of FLG loading, size\n  and dispersion on mechanical and thermal properties: Four series of PLA based composite films containing horizontally aligned few\nlayer graphene (FLG) flakes of high aspect ratio and adsorbed albumin are\nprepared. The mechanical and thermal properties vary with percentage,\ndispersion degree and size of FLG flakes. Great improvement up to 290 and 360%\nof tensile modulus and strength respectively was obtained for the composite\ncontaining high lateral size of FLG at 0.17% wt., and up to 60 and 80% for the\ncomposite with very well dispersed 0.02% wt. FLG. The composites of PLA and\nPEG-PLLA containing very well dispersed FLG flakes at 0.07 % wt. are ductile\nshowing enhancement of elongation at break up to respectively 80 and 88%.\nRelatively high electrical conductivity, 5 x 10-3 S/cm, is measured for PLA\nfilm charged with 3% of FLG.",
        "positive": "Stick boundary conditions and rotational velocity auto-correlation\n  functions for colloidal particles in a coarse-grained representation of the\n  solvent: We show how to implement stick boundary conditions for a spherical colloid in\na solvent that is coarse-grained by the method of stochastic rotation dynamics.\nThis allows us to measure colloidal rotational velocity auto-correlation\nfunctions by direct computer simulation. We find quantitative agreement with\nEnskog theory for short times and with hydrodynamic mode-coupling theory for\nlonger times. For aqueous colloidal suspensions, the Enskog contribution to the\nrotational friction is larger than the hydrodynamic one when the colloidal\nradius drops below 35nm."
    },
    {
        "anchor": "Stability dependence of local structural heterogeneities of stable\n  amorphous solids: The universal anomalous vibrational and thermal properties of amorphous\nsolids are believed to be related to the local variations of the elasticity.\nRecently it has been shown that the vibrational properties are sensitive to the\nglass's stability. Here we study the stability dependence of the local elastic\nconstants of a simulated glass former over a broad range of stabilities, from a\npoorly annealed glass to a glass whose stability is comparable to laboratory\nexceptionally stable vapor deposited glasses. We show that with increasing\nstability the glass becomes more uniform as evidenced by a smaller variance of\nlocal elastic constants. We find that, according to the definition of local\nelastic moduli used in this work, the local elastic moduli are not spatially\ncorrelated.",
        "positive": "Yielding and microstructure in a 2D jammed material under shear\n  deformation: The question of how a disordered material's microstructure translates into\nmacroscopic mechanical response is central to understanding and designing\nmaterials like pastes, foams and metallic glasses. Here, we examine a 2D soft\njammed material under cyclic shear, imaging the structure of ~50,000 particles.\nBelow a certain strain amplitude, the structure becomes conserved at long\ntimes, while above, it continually rearranges. We identify the boundary between\nthese regimes as a yield strain, defined without rheological measurement. Its\nvalue is consistent with a simultaneous but independent measurement of yielding\nby stress-controlled bulk rheometry. While there are virtually no irreversible\nrearrangements in the steady state below yielding, we find a largely stable\npopulation of plastic rearrangements that are reversed with each cycle. These\nresults point to a microscopic view of mechanical properties under cyclic\ndeformation."
    },
    {
        "anchor": "Magnetic Susceptibility of NiO Nanoparticles: Nickel oxide nanoparticles of different sizes are prepared and characterized\nby x-ray diffraction and transmission electron microscopy. A.C. susceptibility\nmeasurements as a function of temperature are carried out for various particle\nsizes and frequencies. We find that the behavior of the system is spin glass\nlike.",
        "positive": "A deformable microswimmer in a swirl: capturing and scattering dynamics: Inspired by the classical Kepler and Rutherford problem, we investigate an\nanalogous set-up in the context of active microswimmers: the behavior of a\ndeformable microswimmer in a swirl flow. First we identify new steady bound\nstates in the swirl flow and analyze their stability. Second we study the\ndynamics of a self-propelled swimmer heading towards the vortex center, and we\nobserve the subsequent capturing and scattering dynamics. We distinguish\nbetween two major types of swimmers, those that tend to elongate\nperpendicularly to the propulsion direction and those that pursue a parallel\nelongation. While the first ones can get caught by the swirl, the second ones\nwere always observed to be scattered, which proposes a promising escape\nstrategy. This offers a route to design artificial microswimmers that show the\ndesired behavior in complicated flow fields. It should be straightforward to\nverify our results in a corresponding quasi-two-dimensional experiment using\nself-propelled droplets on water surfaces."
    },
    {
        "anchor": "Time-Dependent Fluctuations and Superdiffusivity in the Driven Lattice\n  Lorentz Gas: We consider a tracer particle on a lattice in the presence of immobile\nobstacles. Starting from equilibrium, a force pulling on the particle is\nswitched on, driving the system to a new stationary state. We solve for the\ncomplete transient dynamics of the fluctuations of the tracer position along\nthe direction of the force. The analytic result, exact in first order of the\nobstacle density and for arbitrarily strong driving, is compared to stochastic\nsimulations. Upon strong driving, the fluctuations grow superdiffusively for\nintermediate times; however, they always become diffusive in the stationary\nstate. The diffusion constant is nonanalytic for small driving and is enhanced\nby orders of magnitude by increasing the force.",
        "positive": "Nematohydrodynamics for Colloidal Self-Assembly and Transport Phenomena: We study colloidal particles in a nematic-liquid-crystal-filled microfluidic\nchannel and show how elastic interactions between the particle and the channel\nwall lead to different particle dynamics compared with conventional\nmicrofluidics. For a static particle, in the absence of a flow field, the\ndirector orientation on the particle surface undergoes a rapid transition from\nuniform to homeotropic anchoring as a function of the anchoring strength and\nthe particle size. In the presence of a flow field, in addition to fluid\nviscous stresses on the particle, nematic-induced elastic stresses are exerted\nas a result of the anchoring conditions. The resulting forces are shown to\noffer the possibility of size-based separation of individual particles. For\nmulti-particle systems, the nematic forces induce inter-particle attraction\ninduces particle attraction, following which the particles aggregate and\nreorientate. These results illustrate how coupled nematic-hydrodynamic effects\ncan affect the mobility and spatial reorganization of colloidal particles in\nmicrofluidic applications."
    },
    {
        "anchor": "Adhesive contact of model randomly rough rubber surfaces: We study experimentally and theoretically the equilibrium adhesive contact\nbetween a smooth glass lens and a rough rubber surface textured with spherical\nmicroasperities with controlled height and spatial distributions. Measurements\nof the real contact area $A$ versus load $P$ are performed under compression by\nimaging the light transmitted at the microcontacts. $A(P)$ is found to be\nnon-linear and to strongly depend on the standard deviation of the asperity\nheight distribution. Experimental results are discussed in the light of a\ndiscrete version of Fuller and Tabor's (FT) original model (\\textit{Proceedings\nof the Royal Society A} \\textbf{345} (1975) 327), which allows to take into\naccount the elastic coupling arising from both microasperities interactions and\ncurvature of the glass lens. Our experimental data on microcontact size\ndistributions are well captured by our discrete extended model. We show that\nthe elastic coupling arising from the lens curvature has a significant\ncontribution to the $A(P)$ relationship. Our discrete model also clearly shows\nthat the adhesion-induced effect on $A$ remains significant even for\nvanishingly small pull-off forces. Last, at the local asperity length scale,\nour measurements show that the pressure dependence of the microcontacts density\ncan be simply described by the original FT model.",
        "positive": "Jammed Spheres: Minkowski Tensors Reveal Onset of Local Crystallinity: The local structure of disordered jammed packings of monodisperse spheres\nwithout friction, generated by the Lubachevsky-Stillinger algorithm, is studied\nfor packing fractions above and below 64%. The structural similarity of the\nparticle environments to fcc or hcp crystalline packings (local crystallinity)\nis quantified by order metrics based on rank-four Minkowski tensors. We find a\ncritical packing fraction \\phi_c \\approx 0.649, distinctly higher than\npreviously reported values for the contested random close packing limit. At\n\\phi_c, the probability of finding local crystalline configurations first\nbecomes finite and, for larger packing fractions, increases by several orders\nof magnitude. This provides quantitative evidence of an abrupt onset of local\ncrystallinity at \\phi_c. We demonstrate that the identification of local\ncrystallinity by the frequently used local bond-orientational order metric q_6\nproduces false positives, and thus conceals the abrupt onset of local\ncrystallinity. Since the critical packing fraction is significantly above\nresults from mean-field analysis of the mechanical contacts for frictionless\nspheres, it is suggested that dynamic arrest due to isostaticity and the\nalleged geometric phase transition in the Edwards framework may be disconnected\nphenomena."
    },
    {
        "anchor": "Directed migration of microscale swimmers by an array of shaped\n  obstacles: modeling and shape optimization: Achieving macroscopic directed migration of microscale swimmers in a fluid is\nan important step towards utilizing their autonomous motion. It has been\nexperimentally shown that directed motion can be induced, without any external\nfields, by certain geometrically asymmetric obstacles due to interaction\nbetween their boundaries and the swimmers. In this paper, we propose a\nkinetic-type model to study swimming and directional migration of microscale\nbimetallic rods in a periodic array of posts with non-circular cross-sections.\nBoth rod position and orientation are taken into account; rod trapping and\nrelease on the post boundaries are modeled by empirically characterizing\ncurvature and orientational dependence of the boundary absorption and\ndesorption. Intensity of the directed rod migration, which we call the\nnormalized net flux, is then defined and computed given the geometry of the\npost array. We numerically study the effect of post spacings on the flux; we\nalso apply shape optimization to find better post shapes that can induce\nstronger flux. Inspired by preliminary numerical results on two candidate\nposts, we perform an approximate analysis on a simplified model to show the key\ngeometric features a good post should have. Based on that, three new candidate\nshapes are proposed which give rise to large fluxes. This approach provides an\neffective tool and guidance for experimentally designing new devices that\ninduce strong directed migration of microscale swimmers.",
        "positive": "Relaxation of surface charge on rotating dielectric spheres:\n  Implications on dynamic electrorheological effects: We have examined the effect of an oscillatory rotation of a polarized\ndielectric particle. The rotational motion leads to a re-distribution of the\npolarization charge on the surface of the particle. We show that the time\naveraged steady-state dipole moment is along the field direction, but its\nmagnitude is reduced by a factor which depends on the angular velocity of\nrotation. As a result, the rotational motion of the particle reduces the\nelectrorheological effect. We further assume that the relaxation of polarized\ncharge is arised from a finite conductivity of the particle or host medium. We\ncalculate the relaxation time based on the Maxwell-Wagner theory, suitably\ngeneralized to include the rotational motion. Analytic expressions for the\nreduction factor and the relaxation time are given and their dependence on the\nangular velocity of rotation will be discussed."
    },
    {
        "anchor": "Dynamics of Binary Mixtures with Ions: Dynamic Structure Factor and\n  Mesophase Formation: Dynamic equations are presented for polar binary mixtures containing ions in\nthe presence of the preferential solvation. In one-phase states, we calculate\nthe dynamic structure factor of the composition accounting for the ion motions.\nMicrophase separation can take place for sufficiently large solvation asymmetry\nof the cations and the anions. We show two-dimensional simulation results of\nthe mesophase formation with an antagonistic salt, where the cations are\nhydrophilic and the anions are hydrophobic. The structure factor S(q) in the\nresultant mesophase has a sharp peak at an intermediate wave number on the\norder of the Debye-Huckel wave number. As the quench depth is increased, the\nsurface tension nearly vanishes in mesophases due to an electric double layer.",
        "positive": "Self-assembly of active amphiphilic Janus particles: In this article, we study the phenomenology of a two dimensional dilute\nsuspension of active amphiphilic Janus particles. We analyze how the morphology\nof the aggregates emerging from their self-assembly depends on the strength and\nthe direction of the active forces. We systematically explore and contrast the\nphenomenologies resulting from particles with a range of attractive patch\ncoverages. Finally, we illustrate how the geometry of the colloids and the\ndirectionality of their interactions can be used to control the physical\nproperties of the assembled active aggregates and suggest possible strategies\nto exploit self-propulsion as a tunable driving force for self-assembly."
    },
    {
        "anchor": "Dynamics of a Monolayer of Microspheres on an Elastic Substrate: We present a model for wave propagation in a monolayer of spheres on an\nelastic substrate. The model, which considers sagittally polarized waves,\nincludes: horizontal, vertical, and rotational degrees of freedom; normal and\nshear coupling between the spheres and substrate, as well as between adjacent\nspheres; and the effects of wave propagation in the elastic substrate. For a\nmonolayer of interacting spheres, we find three contact resonances, whose\nfrequencies are given by simple closed-form expressions. For a monolayer of\nisolated spheres, only two resonances are present. The contact resonances\ncouple to surface acoustic waves in the substrate, leading to mode\nhybridization and \"avoided crossing\" phenomena. We present dispersion curves\nfor a monolayer of silica microspheres on a silica substrate, assuming\nadhesive, Hertzian interactions, and compare calculations using an effective\nmedium approximation to a discrete model of a monolayer on a rigid substrate.\nWhile the effective medium model does not account for discrete lattice effects\nat short wavelengths, we find that it is well suited for describing the\ninteraction between the monolayer and substrate in the long wavelength limit.\nWe suggest that a complete picture of the dynamics of a discrete monolayer\nadhered to an elastic substrate can be found using a combination of the results\npresented for the discrete and effective medium descriptions. This model is\npotentially scalable for use with both micro- and macroscale systems, and\noffers the prospect of experimentally extracting contact stiffnesses from\nmeasurements of acoustic dispersion.",
        "positive": "Self-assembled granular walkers: Mechanisms of locomotion in microscopic systems are of great interest not\nonly for technological applications, but also for the sake of understanding,\nand potentially harnessing, processes far from thermal equilibrium.\nDown-scaling is a particular challenge, and has led to a number of interesting\nconcepts including thermal ratchet systems and asymmetric swimmers. Here we\npresent a system which is particularly intriguing, as it is self-assembling and\nuses a robust mechanism which can be implemented in various settings. It\nconsists of small spheres of different size which adhere to each other, and are\nsubject to an oscillating (zero average) external force eld. An inherent\nnonlinearity in the mutual force network leads to force rectication and hence\nto locomotion. We present a model that accounts for the observed behaviour and\ndemonstrates the wide applicability and potential scalability of the concept."
    },
    {
        "anchor": "Elasticity in crystals with high density of local defects : insights\n  from ultra-soft colloids: In complex crystals close to melting or at finite temperatures, different\ntypes of defects are ubiquitous and their role becomes relevant in the\nmechanical response of these solids. Conventional elasticity theory fails to\nprovide a microscopic basis to include and account for the motion of\npoint-defects in an otherwise ordered crystalline structure. We study the\nelastic properties of a point-defect rich crystal within a first-principles\ntheoretical framework derived from microscopic equations of motion. This\nframework allows us to make specific predictions pertaining to the mechanical\nproperties which we can validate through deformation experiments performed in\nMolecular Dynamics simulations.",
        "positive": "Simulations of Liquid Bilayer and the Hunt for Protrusions: New simulations are reported of a single bilayer immersed in a liquid\nsolvent, using a simple extension of the model of the Max-Plack group and of\nmodel used in earlier work. Fluctuation spectrum vel structure factor is\ndissected in detail and the role of bulk fluctuations is revealed.We propose to\nsearch for protrusions direcdtly where they are, i.e. at the solvent-heads\nboundary. In this context new single-point quantities and new two-point\ncorrelations are introduced and determined for the solvent-head pairs. Most\nunusual shapes are obtained."
    },
    {
        "anchor": "Invited review: Effect of temperature on a granular pile: As a fragile construction, a granular pile is very sensitive to minute\nexternal perturbations. In particular, it is now well established that a\ngranular assembly is sensitive to variations of temperature. Such variations\ncan produce localized rearrangements as well as global static avalanches inside\na pile. In this review, we sum up the various observations that have been made\nconcerning the effect of temperature on a granular assembly. In particular, we\ndwell on the way controlled variations of temperature have been employed to\ngenerate the compaction of a granular pile. After laying emphasis on the key\nfeatures of this compaction process, we compare it to the classic\nvibration-induced compaction. Finally, we also review other granular systems in\na large sense, from microscopic (jammed multilamellar vesicles) to macroscopic\nscales (stone heave phenomenon linked to freezing and thawing of soils) for\nwhich periodic variations of temperature could play a key role in the dynamics\nat stake.",
        "positive": "Percolating Plastic Failure as a Mechanism for Shear Softening in\n  Amorphous Solids: ``Shear softening\" refers to the observed reduction in shear modulus when the\nstress on an amorphous solid is increased beyond the initial linear region.\nCareful numerical quasi-static simulations reveal an intimate relation between\nplastic failure and shear softening. The attaintment of the steady-state value\nof the shear modulus associated with plastic flow is identified with a\npercolation of the regions that underwent a plastic event. We present an\nelementary ``two-state\" model that interpolates between failed and virgin\nregions and provides a simple and effective characterization of the shear\nsoftening."
    },
    {
        "anchor": "Collective enhancement and suppression in Bose-Einstein condensates: The coherent and collective nature of Bose-Einstein condensate can enhance or\nsuppress physical processes. Bosonic stimulation enhances scattering in already\noccupied states which leads to atom amplification, and the suppression of\ndissipation leads to superfluidity. In this paper, we review several\nexperiments where suppression and enhancement have been observed and discuss\nthe common roots of and differences between these phenomena.",
        "positive": "Origin and Detection of Microstructural Clustering in Fluids with\n  Spatial-Range Competitive Interactions: Fluids with competing short-range attractions and long-range repulsions mimic\ndispersions of charge-stabilized colloids that can display equilibrium\nstructures with intermediate range order (IRO), including particle clusters.\nUsing simulations and analytical theory, we demonstrate how to detect cluster\nformation in such systems from the static structure factor and elucidate links\nto macrophase separation in purely attractive reference fluids. We find that\nclusters emerge when the thermal correlation length encoded in the IRO peak of\nthe structure factor exceeds the characteristic lengthscale of interparticle\nrepulsions. We also identify qualitative differences between the dynamics of\nsystems that form amorphous versus micro-crystalline clusters."
    },
    {
        "anchor": "Magneto-sensitive elastomers in a homogeneous magnetic field: a regular\n  rectangular lattice model: A theory of mechanical behaviour of the magneto-sensitive elastomers is\ndeveloped in the framework of a linear elasticity approach. Using a regular\nrectangular lattice model, different spatial distributions of magnetic\nparticles within a polymer matrix are considered: isotropic, chain-like and\nplane-like. It is shown that interaction between the magnetic particles results\nin the contraction of an elastomer along the homogeneous magnetic field. With\nincreasing magnetic field the shear modulus for the shear deformation\nperpendicular to the magnetic field increases for all spatial distributions of\nmagnetic particles. At the same time, with increasing magnetic field the\nYoung's modulus for tensile deformation along the magnetic field decreases for\nboth chain-like and isotropic distributions of magnetic particles and increases\nfor the plane-like distribution of magnetic particles.",
        "positive": "Influence of fatty alcohol mixing ratios on the physicochemical\n  properties of Stearyl--Cetyl Alcohol--Polysorbate 60--Water ternary System:\n  Insights from Experiments and Computer Simulations: The structure and stability of ternary systems prepared with polysorbate 60\nand various combinations of cetyl (C16) and stearyl (C18) alcohols (fatty\nalcohol 16g, polysorbate 4g, water 180g) were examined as they aged over 3\nmonths at 25oC. Rheological results showed that the consistency of these\nsystems increased initially during roughly the first week of aging, which was\nsucceeded by little changes in consistency (systems containing from 30% to 70%\nC18, with the 50% C18 system showing the highest consistencies in viscosity and\nelasticity) or significant breakdown of structure (remaining systems). The\nformation and/or disintegration of all ternary systems were also detected by\nmicroscopy and differential scanning calorimetry experiments. This study\nemphasizes the fact that the structure and consistency of ternary systems are\ndominantly controlled by the swelling capacity of the lamellar\n$\\alpha-$crystalline gel phase. When the conversion of this gel phase into\nnon-swollen $\\beta$- or $\\gamma$-crystals occurs, systems change from\nsemisolids to fluids. Molecular dynamics simulations were performed to provide\nimportant details on the molecular mechanism of our ternary systems.\nComputational results supported the hypothesis experimentally proposed for the\nstability of the mixed system being due to an increase in the flexibility,\nhence an increase in the configurational entropy of the chain tip of the\nalcohol with a longer hydrocarbon chain (with the highest flexibility observed\nin the 50:50 C18:C16 system). This finding is in excellent agreement with\nexperimental conclusions. Additionally, simulation data show that in the mixed\nsystem, the alcohol with shorter hydrocarbon chain becomes more rigid. These\nmolecular details could not be available in experimental measurements"
    },
    {
        "anchor": "Emergent collective motion of self-propelled condensate droplets: Recently, there is much interest in droplet condensation on soft or\nliquid/liquid-like substrates. Droplets can deform soft and liquid interfaces\nresulting in a wealth of phenomena not observed on hard, solid surfaces (e.g.,\nincreased nucleation, inter-droplet attraction). Here, we describe a unique\ncomplex collective motion of condensate water droplets that emerges\nspontaneously when a solid substrate is covered with a thin oil film. Droplets\nmove first in a serpentine, self-avoiding fashion before transitioning to\ncircular motions. We show that this self-propulsion (with speeds in the 0.1-1\nmm/s range) is fuelled by the interfacial energy release upon merging with\nnewly condensed but much smaller droplets. The resultant collective motion\nspans multiple length scales from submillimetre to several centimetres, with\npotentially important heat-transfer and water-harvesting applications.",
        "positive": "Confined flow of suspensions modeled by a frictional rheology: We investigate in detail the problem of confined pressure-driven laminar flow\nof neutrally buoyant non-Brownian suspensions using a frictional rheology based\non the recent proposal of Boyer et al., 2011. The friction coefficient and\nsolid volume fraction are taken as functions of the dimensionless viscous\nnumber I defined as the ratio between the fluid shear stress and the particle\nnormal stress. We clarify the contributions of the contact and hydrodynamic\ninteractions on the evolution of the friction coefficient between the dilute\nand dense regimes reducing the phenomenological constitutive description to\nthree physical parameters. We also propose an extension of this constitutive\nlaw from the flowing regime to the fully jammed state. We obtain an analytical\nsolution of the fully-developed flow in channel and pipe for the frictional\nsuspension rheology. The result can be transposed to dry granular flow upon\nappropriate redefinition of the dimensionless number I. The predictions are in\nexcellent agreement with available experimental results, when using the values\nof the constitutive parameters obtained independently from stress-controlled\nrheological measurements. In particular, the frictional rheology correctly\npredicts the transition from Poiseuille to plug flow and the associated\nparticles migration with the increase of the entrance solid volume fraction. We\nnumerically solve for the axial development of the flow from the inlet of the\nchannel/pipe toward the fully-developed state. The available experimental data\nare in good agreement with our predictions. The solution of the axial\ndevelopment of the flow provides a quantitative estimation of the entrance\nlength effect in pipe for suspensions. A analytical expression for development\nlength is shown to encapsulate the numerical solution in the entire range of\nflow conditions from dilute to dense."
    },
    {
        "anchor": "Crystalline multilayers of the confined Yukawa system: The phase diagram of Yukawa particles confined between two parallel hard\nwalls is calculated at zero-temperature beyond the bilayer regime by\nlattice-sum-minimization. Tuning the screening, a rich phase behavior is found\nin the regime bounded by stable two-triangular layers and 3-square layers. In\nthis regime, alternating prism phases with square and triangular basis,\nstructures derived from a hcp bulk lattice, and a structure with two outer\nlayers and two inner staggered rectangular layers, reminiscent of a Belgian\nwaffle iron, are stable. These structures are verifiable in experiments on\ncharged colloidal suspensions and dusty plasma sheets.",
        "positive": "Rotation of a liquid crystal by the Casimir torque: We present a calculation of the Casimir torque acting on a liquid crystal\nnear a birefringent crystal. In this system, a liquid crystal bulk is uniformly\naligned at one surface and is twisted at the other surface by a birefringent\ncrystal, e.g. barium titanate. The liquid crystal is separated from the solid\ncrystal by an isotropic, transparent material such as SiO$_2$. By varying the\nthickness of the deposited layer, we can observe the effect of retardation on\nthe torque (which differentiates it from the close-range van der Waals torque).\nWe find that a barium titanate slab would cause 5CB\n(4-cyano-4$'$-pentylbiphenyl) liquid crystal to rotate by 10$^\\circ$ through\nits bulk when separated by 35 nm of SiO$_2$. The optical technique for\nmeasuring this twist is also outlined."
    },
    {
        "anchor": "Detection of Islands and Droplets on Smectic Films Using Machine\n  Learning: Machine learning techniques have been developed to identify inclusions on the\nsurface of freely suspended smectic liquid crystal films imaged by reflected\nlight microscopy. The experimental images are preprocessed using Canny edge\ndetection and then passed to a radial kernel support vector machine (SVM)\ntrained to recognize circular islands and droplets. The SVM is able to identify\nthese objects of interest with an accuracy that far exceeds that of\nconventional tracking software, especially when the background image is\nnon-uniform or when the target features are in close proximity to one another.\nThis method could be applied to tracking objects in a variety of visually\ninhomogeneous biological and soft matter environments, in order to study growth\ndynamics, the development of spatial order, and hydrodynamic behavio",
        "positive": "Elucidating contact electrification mechanism of water: The open water surface is known to be charged. Yet, the magnitude of the\ncharge and the physical mechanism of the charging remain unclear, causing\nheated debates across the scientific community. Here we directly measure the\ncharge Q of microdrops ejected from hydrophilic and hydrophobic capillaries and\nshow that the water surface can take both positive or negative charge values\ndepending on pH and the capillary type. Our experiments, theory, and\nsimulations provide evidence that a junction of two aqueous interfaces with a\ndifferent ion adsorption energy (e.g., liquid-solid and liquid-air interfaces)\ndevelops a pH-dependent contact potential difference {\\Delta}{\\phi} up to 52\nmV. The longitudinal charge transfer between the interfaces stimulated by\n{\\Delta}{\\phi} determines the charge of the open water surface. The suggested\nstatic electrification mechanism provides far-reaching insights into the origin\nof electrical potentials in biological and electrochemical energy systems."
    },
    {
        "anchor": "Translocation time of periodically forced polymer chains: We show the presence of both a minimum and clear oscillations in the\nfrequency dependence of the translocation time of a polymer described as a\nunidimensional Rouse chain driven by a spatially localized oscillating linear\npotential. The observed oscillations of the mean translocation time arise from\nthe synchronization between the very mean translocation time and the period of\nthe external force. We have checked the robustness of the frequency value for\nthe minimum translocation time by changing the damping parameter, finding a\nvery simple relationship between this frequency and the correspondent\ntranslocation time. The translocation time as a function of the polymer length\nhas been also evaluated, finding a precise $L^2$ scaling. Furthermore, the role\nplayed by the thermal fluctuations described as a Gaussian uncorrelated noise\nhas been also investigated, and the analogies with the resonant activation\nphenomenon are commented.",
        "positive": "Simultaneous thermoosmotic and thermoelectric responses in nanoconfined\n  electrolyte solutions: Effects of nanopore structures and membrane properties: Hypothesis: Nanofluidic systems provide an emerging and efficient platform\nfor thermoelectric conversion and fluid pumping with low-grade heat energy. As\na basis of their performance enhancement, the effects of the structures and\nproperties of the nanofluidic systems on the thermoelectric response (TER) and\nthe thermoosmotic response (TOR) are yet to be explored. Methods: The\nsimultaneous TER and TOR of electrolyte solutions in nanofluidic membrane pores\non which an axial temperature gradient is exerted are investigated numerically\nand semi-analytically. A semi-analytical model is developed with the\nconsideration of finite membrane thermal conductivity and the\nreservoir/entrance effect. Findings: The increase in the access resistance due\nto the nanopore-reservoir interfaces accounts for the decrease of short circuit\ncurrent at the low concentration regime. The decrease in the thermal\nconductivity ratio can enhance the TER and TOR. The maximum power density\noccurring at the nanopore radius twice the Debye length ranges from several to\ndozens of mW K$^{-2}$ m$^{-2}$ and is an order of magnitude higher than typical\nthermo-supercapacitors. The surface charge polarity can heavily affect the sign\nand magnitude of the short-circuit current, the Seebeck coefficient, and the\nopen-circuit thermoosmotic coefficient, but has less effect on the\nshort-circuit thermoosmotic coefficient. Furthermore, the membrane thickness\nmakes different impacts on TER and TOR for zero and finite membrane thermal\nconductivity."
    },
    {
        "anchor": "Opposite translocation of long and short oligomers through a nanopore: We consider elongated cylindrical particles, modeling e.g. DNA fragments or\nnano-rods, while translocating under the action of an externally applied\nvoltage through a solid state nanopore. Particular emphasis is put on the\nconcomitant potential energy landscape, encountered by the particle on its\npassage through the pore due to the complex interplay of various\nelectrohydrodynamic effects beyond the realm of small Debye lengths. We find\nthat the net potential energy difference across the membrane may be of opposite\nsign for short and long particles of equal diameters and charge densities (e.g.\noligomers). Thermal noise thus leads to biased diffusion through the pore into\nopposite directions. By means of an additional membrane gate electrode it is\neven possible to control the specific particle length at which this transport\ninversion occurs.",
        "positive": "Suppression and enhancement of impurity scattering in a Bose-Einstein\n  condensate: Impurity atoms propagating at variable velocities through a trapped\nBose-Einstein condensate were produced using a stimulated Raman transition. The\nredistribution of momentum by collisions between the impurity atoms and the\nstationary condensate was observed in a time-of-flight analysis. The\ncollisional cross section was dramatically reduced when the velocity of the\nimpurities was reduced below the speed of sound of the condensate, in agreement\nwith the Landau criterion for superfluidity. For large numbers of impurity\natoms, we observed an enhancement of atomic collisions due to bosonic\nstimulation. This enhancement is analogous to optical superradiance."
    },
    {
        "anchor": "Trapping Fermionic $^{40}$K and Bosonic $^{87}$Rb on a Chip: We demonstrate the loading of a Bose-Fermi mixture into a microfabricated\nmagnetic trap. In a single-chamber vacuum system, laser-cooled atoms are\ntransported to the surface of a substrate on which gold wires have been\nmicrofabricated. The magnetic field minimum formed near these current-carrying\nwires is used to confine up to $6\\times10^4$ neutral $^{40}$K atoms. In\naddition, we can simultaneously load $2 \\times 10^5$ $^{87}$Rb atoms,\ndemonstrating the confinement of two distinct elements with such a trap. In a\nsequence optimized for $^{87}$Rb alone, we observe up to $1 \\times 10^7$\ntrapped atoms. We describe in detail the experimental apparatus, and discuss\nprospects for evaporative cooling towards quantum degeneracy in both species.",
        "positive": "Swimming at Low Reynolds Number in Fluids with Odd (Hall) Viscosity: We apply the geometric theory of swimming at low Reynolds number to the study\nof nearly circular swimmers in two-dimensional fluids with non-vanishing Hall,\nor \"odd\", viscosity. The Hall viscosity gives an off-diagonal contribution to\nthe fluid stress-tensor, which results in a number of striking effects. In\nparticular, we find that a swimmer whose area is changing will experience a\ntorque proportional to the rate of change of the area, with the constant of\nproportionality given by the coefficient $\\eta^o$ of odd viscosity. After\nworking out the general theory of swimming in fluids with Hall viscosity for a\nclass of simple swimmers, we give a number of example swimming strokes which\nclearly demonstrate the differences between swimming in a fluid with\nconventional viscosity and a fluid which also has a Hall viscosity. A number of\nmore technical results, including a proof of the torque-area relation for\nswimmers of more general shape, are explained in a set of appendices."
    },
    {
        "anchor": "End Grafted Polymer Nanoparticles in a Polymeric Matrix: Effect of\n  Coverage and Curvature: It has recently been proposed that the miscibility of nanoparticles with a\npolymer matrix can be controlled by grafting polymer chains to the nanoparticle\nsurface. As a first step to study this situation, we have used molecular\ndynamics simulations on a single nanoparticle of radius R ($4\\sigma \\le$R$\\le\n16\\sigma$, where $\\sigma$ is the diameter of a polymer monomer) grafted with\nchains of length 500 in a polymer melt of chains of length 1000. The grafting\ndensity $\\Sigma$ was varied between $0.04$-$0.32$ chains/$\\sigma^2$. To\nfacilitate equilibration a Monte Carlo double-bridging algorithm is applied -\nnew bonds are formed across a pair of chains, creating two new chains each\nsubstantially different from the original. For the long brush chains studied\nhere, the structure of the brush assumes its large particle limit even for $R$\nas small as 8$\\sigma$, which is consistent with recent experimental findings.\nWe study autophobic dewetting of the melt from the brush as a function of\nincreasing $\\Sigma$. Even these long brush and matrix chains of length $6$ and\n$12$ $N_e$, respectively, (the entanglement length is $N_e \\sim 85$) give\nsomewhat ambiguous results for the interfacial width, showing that studies of\ntwo or more nanoparticles are necessary to properly understand these\nmiscibility issues. Entanglement between the brush and melt chains were\nidentified using the primitive path analysis. We find that the number of\nentanglements between the brush and melt chains scale simply with the product\nof the local monomer densities of brush and melt chains.",
        "positive": "Impact of the inner solute structure on the electrostatic mean-field and\n  strong-coupling regimes of macromolecular interactions: The structural diversity of the solute molecules involved in biomolecular\nprocesses necessitates the characterization of the forces between charged\nmacromolecules beyond the point-ion description. From the field theoretic\npartition function of an electrolyte confined between two anionic membranes, we\nderive a contact-value identity valid for general intramolecular solute\nstructure and electrostatic coupling strength. In the electrostatic mean-field\n(MF) regime, the inner charge spread of the solute particles is shown to induce\nthe twofold enhancement of the short-range Poisson-Boltzmann (PB)-level\nmembrane repulsion, and a longer-range depletion attraction. Our contact\ntheorem indicates that the twofold repulsion enhancement by solute size is\nequally present in the opposite strong-coupling (SC) regime of linear and\nspherical solute molecules. Upon the inclusion of the dielectric contrast\nbetween the electrolyte and the interacting membranes, the emerging\npolarization forces substantially amplify the solute specificity of the\nmacromolecular interactions. Namely, the finite size of the solute particles\ncomposed of similar terminal charges such as putrescine molecules weaken the\nintermembrane repulsion. However, the extended structure of the solute\nmolecules carrying opposite elementary charges such as ionized atoms and\nzwitterionic molecules enhance the membrane repulsion by several factors. We\nalso show that these polarization forces can extend the range of the solute\nstructure effects up to intermembrane distances exceeding the solute size by an\norder of magnitude. This radical alteration of the intermembrane interactions\nby the salt structure identifies the solute specificity as a key ingredient of\nthe thermodynamic stability in colloidal systems."
    },
    {
        "anchor": "Plastic deformation of tubular crystals by dislocation glide: Tubular crystals, two-dimensional lattices wrapped into cylindrical\ntopologies, arise in many contexts, including botany and biofilaments, and in\nphysical systems such as carbon nanotubes. The geometrical principles of\nbotanical phyllotaxis, describing the spiral packings on cylinders commonly\nfound in nature, have found application in all these systems. Several recent\nstudies have examined defects in tubular crystals associated with crystalline\npackings that must accommodate a fixed tube radius. Here, we study the\nmechanics of tubular crystals with variable tube radius, with dislocations\ninterposed between regions of different phyllotactic packings. Unbinding and\nseparation of dislocation pairs with equal and opposite Burgers vectors allow\nthe growth of one phyllotactic domain at the expense of another. In particular,\nglide separation of dislocations offers a low-energy mode for plastic\ndeformations of solid tubes in response to external stresses, reconfiguring the\nlattice step by step. Through theory and simulation, we examine how the tube's\nradius and helicity affects, and is in turn altered by, the mechanics of\ndislocation glide. We also discuss how a sufficiently strong bending rigidity\ncan alter or arrest the deformations of tubes with small radii.",
        "positive": "Water's interfacial hydrogen bonding structure reveals the effective\n  strength of surface-water interactions: The interactions of a hydrophilic surface with water can significantly\ninfluence the characteristics of the liquid water interface. In this\nmanuscript, we explore this influence by studying the molecular structure of\nliquid water at a disordered surface with tunable surface-water interactions.\nWe combine all-atom molecular dynamics simulations with a mean field model of\ninterfacial hydrogen bonding to analyze the effect of surface-water\ninteractions on the structural and energetic properties of the liquid water\ninterface. We find that the molecular structure of water at a weakly\ninteracting (i.e., hydrophobic) surface is resistant to change unless the\nstrength of surface-water interactions are above a certain threshold. We find\nthat below this threshold water's interfacial structure is homogeneous and\ninsensitive to the details of the disordered surface, however, above this\nthreshold water's interfacial structure is heterogeneous. Despite this\nheterogeneity, we demonstrate that the equilibrium distribution of molecular\norientations can be used to quantify the energetic component of the\nsurface-water interactions that contribute specifically to modifying the\ninterfacial hydrogen bonding network. We identify this specific energetic\ncomponent as a new measure of hydrophilicity, which we refer to as the\nintrinsic hydropathy."
    },
    {
        "anchor": "Violations of conservation laws in viscous liquid dynamics: The laws expressing conservation of momentum and energy apply to any isolated\nsystem, but these laws are violated for for highly viscous liquids under\nlaboratory conditions because of the unavoidable interactions with the\nmeasuring equipment over the long times needed to study the dynamics. Although\nparticle number conservation applies strictly for any liquid, the solidity of\nviscous liquids implies that even this conservation law is apparently violated\nin coarse-grained descriptions of density fluctuations.",
        "positive": "Heterogeneous Digital Stiffness Programming: Digital stiffness programmability is fulfilled with a heterogeneous\nmechanical metamaterial. The prototype consists of an elastomer matrix\ncontaining tessellations of diamond shaped cavities selectively confined with\nsemi-rigid plastic beam inserts along their diagonals. Unit-cell perturbations\nby placing or removing each insert reshape the global constitutive relation\nwhose lower and upper bounds corresponding to the configurations with all holes\nempty and all inserts in place, respectively, are significantly distant from\neach other thanks to a gap between the moduli of the elastomer and the inserts.\nBidirectional operation is achieved by mixing insert orientations where\nlongitudinal inserts enhance the macroscopic stiffness in compression and\ntransverse ones tension. Arranged digital representations of such local insert\nstates form the explicit encoding of global patterns so that systematic\nstiffness programming with minimal changes in mass is enabled both statically\nand in situ. These characteristics establish a new paradigm in actively tuning\nvibration isolation systems according to shifts in the resonance of base\nstructures."
    },
    {
        "anchor": "Measuring magnetic moments of polydisperse ferrofluids utilizing the\n  inverse Langevin function: The dipole strength of magnetic particles in a suspension is obtained by a\ngraphical rectification of the magnetization curves based on the inverse\nLangevin function. The method yields the arithmetic and the harmonic mean of\nthe particle distribution. It has an advantage compared to the fitting of\nmagnetization curves to some appropriate mathematical model: It does not rely\non assuming a particular distribution function of the particles.",
        "positive": "Rouse Modes of Self-avoiding Flexible Polymers: Using a lattice-based Monte Carlo code for simulating self-avoiding flexible\npolymers in three dimensions in the absence of explicit hydrodynamics, we study\ntheir Rouse modes. For self-avoiding polymers, the Rouse modes are not expected\nto be statistically independent; nevertheless, we demonstrate that numerically\nthese modes maintain a high degree of statistical independence. Based on\nhigh-precision simulation data we put forward an approximate analytical\nexpression for the mode amplitude correlation functions for long polymers. From\nthis, we derive analytically and confirm numerically several scaling properties\nfor self-avoiding flexible polymers, such as (i) the real-space end-to-end\ndistance, (ii) the end-to-end vector correlation function, (iii) the\ncorrelation function of the small spatial vector connecting two nearby monomers\nat the middle of a polymer, and (iv) the anomalous dynamics of the middle\nmonomer. Importantly, expanding on our recent work on the theory of polymer\ntranslocation, we also demonstrate that the anomalous dynamics of the middle\nmonomer can be obtained from the forces it experiences, by the use of the\nfluctuation-dissipation theorem."
    },
    {
        "anchor": "Morphological Study of Granular-Granular Impact Craters through\n  Time-of-Flight Cameras: from Concept to Automation in Python: Laboratory made granular-granular impact craters have been used as model\nanalogues of planetary impact craters. These kind of craters have been observed\nand studied using profilometry techniques that allow to retrieve important\nmorphologic features from the impacted surface. In this work, we propose to use\na Time-of-Flight camera (Microsoft Kinect One) for the acquisition of depth\ndata. We show comparisons between the typically used technique and the analysis\nderived from the Time-of-Flight data. We also release craterslab, a Python\nlibrary developed to automate most of the tasks from the process of studying\nimpact craters produced by granular projectiles hitting on the surface of\ngranular targets. The library is able to acquire, identify, and measure\nmorphological features of impacted surfaces through the reconstruction of 3D\ntopographic maps. Our results show that using a Time-of-Flight camera and\nautomating the data processing with a software library for the systematic study\nof impact craters can produce very accurate results while reducing the time\nspent on different stages of the process.",
        "positive": "Negative Gaussian curvature from induced metric changes: We revisit the light or heat-induced changes in topography of initially flat\nsheets of solid that elongate or contract along patterned, in-plane director\nfields. For radial or azimuthal directors, negative Gaussian curvature is\ngenerated -- so-called \"anti-cones\". We show that azimuthal material\ndisplacements are required for the distorted state to be stretch-free and\nbend-minimising. The resultant shapes are smooth and aster-like and can become\nre-entrant in the azimuthal coordinate for large deformations. We show that\ncare is needed when considering elastomers rather than glasses, though the\nformer offer huge deformations."
    },
    {
        "anchor": "Energy dissipation and fluctuations in a driven liquid: Minimal models of active and driven particles have recently been used to\nelucidate many properties non-equilibrium systems. However, the relation\nbetween energy consumption and changes in the structure and transport\nproperties of these non-equilibrium materials remains to be explored. We\nexplore this relation in a minimal model of a driven liquid that settles into a\ntime periodic steady state. Using concepts from stochastic thermodynamics and\nliquid state theories, we show how the work performed on the system by the\nvarious non-conservative, time dependent forces - this quantifies a violation\nof time reversal symmetry - modifies the structural, transport, and phase\ntransition properties of the driven liquid",
        "positive": "Estimating the Strength of an Elastic Network Using Linear Response: Disordered networks of fragile elastic elements have been proposed as a model\nfor inner porous regions of large bones [Gunaratne et.al., cond-mat/0009221].\nIn numerical studies, weakening of such networks is seen to be accompanied by\nreductions in the fraction of load carrying bonds. This observation is used to\nshow that the ratio $\\Gamma$ of linear responses of networks to DC and AC\ndriving can be used as a surrogate for their strength. The possibility of using\n$\\Gamma$ as a non-invasive diagnostic of osteoporotic bone is discussed."
    },
    {
        "anchor": "Annealed lattice animal model and Flory theory for the melt of\n  non-concatenated rings: Towards the physics of crumpling: A Flory theory is constructed for a long polymer ring in a melt of unknotted\nand non-concatenated rings. The theory assumes that the ring forms an effective\nannealed branched object and computes its primitive path. It is shown that the\nprimitive path follows self-avoiding statistics and is characterized by the\ncorresponding Flory exponent of a polymer with excluded volume. Based on that,\nit is shown that rings in the melt are compact objects with overall size\nproportional to their length raised to the 1/3 power. Furthermore, the contact\nprobability exponent is estimated, albeit by a poorly controlled approximation,\nwith the result consistent with both numerical and experimental data.",
        "positive": "Cylinder-flat contact mechanics with surface roughness: We study the nominal (ensemble averaged) contact pressure $p(x)$ acting on a\ncylinder squeezed in contact with an elastic half-space with random surface\nroughness. The contact pressure is Hertzian-like for $\\alpha < 0.01$ and\nGaussian-like for $\\alpha > 10$, where the dimensionless parameter $\\alpha =\nh_{\\rm rms}/\\delta$ is the ratio between the root-mean-square roughness\namplitude and the penetration for the smooth surfaces case (Hertz contact)."
    },
    {
        "anchor": "Wall friction and Janssen effect in the solidification of suspensions: We address the mechanical effect of rigid boundaries on freezing suspensions.\nFor this we perform the directional solidification of monodispersed suspensions\nin thin samples and we document the thickness h of the dense particle layer\nthat builds up at the solidification front. We evidence a change of regime in\nthe evolution of h with the solidification velocity V with, at large velocity,\nan inverse proportionality and, at low velocity, a much weaker trend. By\nmodelling the force balance in the critical state for particle trapping and the\ndissipation phenomena in the whole layer, we link the former evolution to\nviscous dissipation and the latter evolution to solid friction at the rigid\nsample plates. Solid friction is shown to induce an analog of the Janssen\neffect on the whole layer. We determine its dependence on the friction\ncoefficient between particles and plates, on the Janssen's redirection\ncoefficient in the particle layer, and on the sample depth. Fits of the\nresulting relationship to data confirm its relevance at all sample depths and\nprovide quantitative determinations of the main parameters, especially the\nJanssen's characteristic length and the transition thickness h between the\nabove regimes. Altogether, this study thus clarifies the mechanical implication\nof boundaries on freezing suspensions and, on a general viewpoint, provides a\nbridge between the issues of freezing suspensions and of granular materials.",
        "positive": "Enhancing ordering dynamics in solvent-annealed block-copolymer films by\n  lithographic hard masks supports: We studied solvent-driven ordering dynamics of block copolymer films\nsupported by a densely cross-linked polymer network designed as organic hard\nmask (HM) for lithographic fabrications. The ordering of microphase separated\ndomains at low degrees of swelling corresponding to intermediate/strong\nsegregation regimes was found to proceed significantly faster in films on a HM\nlayer as compared to similar block copolymer films on silicon wafers. The\nten-fold enhancement of the chain mobility was evident in the dynamics of\nmorphological phase transitions and of related process of terrace-formation on\na macroscale, as well as in the degree of long-range lateral order of\nnanostructures. The effect is independent of the chemical structure and on the\nvolume composition (cylinder-/ lamella-forming) of the block copolymers.\nIn-situ ellipsometric measurements of the swelling behavior revealed a\ncumulative increase in 1-3 vol. % in solvent up-take by HM-block copolymer\nbilayer films, so that we suggest other than dilution effect reasons for the\nobserved significant enhancement of the chain mobility in concentrated block\ncopolymer solutions. Another beneficial effect of the HM-support is the\nsuppression of the film dewetting which holds true even for low molecular\nweight homopolymer polystyrene films at high degrees of swelling. Apart from\nimmediate technological impact in block copolymer-assisted nanolithography, our\nfindings convey novel insight into effects of molecular architecture on\npolymer-solvent interactions."
    },
    {
        "anchor": "Protein viscoelastic dynamics: a model system: A model system inspired by recent experiments on the dynamics of a folded\nprotein under the influence of a sinusoidal force is investigated and found to\nreplicate many of the response characteristics of such a system. The essence of\nthe model is a strongly over-damped oscillator described by a harmonic\nrestoring force for small displacements that reversibly yields to stress under\nsufficiently large displacement. This simple dynamical system also reveals\nunexpectedly rich behavior, exhibiting a series of dynamical transitions and\nanalogies with equilibrium thermodynamic phase transitions. The effects of\nnoise and of inertia are briefly considered and described.",
        "positive": "Theoretical and Experimental Modelling of Bubble Formation with\n  Connected Capillaries in Liquid Composite Moulding Processes: The void prediction in LCM processes sparks off interest within the composite\nmaterial industry because it is a significant issue to keep the expected\nmechanical properties. The liquid properties, the preform geometry and the flow\nconditions impact the quantity of void entrapped inside the final product. The\ncomplex geometry of the reinforcement due to the arrangement of the bundles and\nthe fibres is a key point to understand and quantify this phenomenon. This\npaper deals with both simple model networks which can occur inside a fabric\nrepresenting connected capillaries, so-called \"Pore Doublet Model (PDM)\". A\nfirst is considering two capillaries converging on a node (T-junction) and a\nsecond is representing two capillaries interconnected with a supplying\nprinciple. These configurations can affect locally the evolution of flow\nfronts. First, experiments of bubble formed in a T-junction device have been\nperformed and studied. Then a theoretical approach was proposed to forecast\nmicrovoid and macrovoid formation, by taking into account a supplying principle\nand arranged Washburn equation in forced filling."
    },
    {
        "anchor": "Polymorph selection during crystallization of a model colloidal fluid\n  with a free energy landscape containing a metastable solid: The free energy landscape responsible for crystallization can be complex even\nfor relatively simple systems like hard sphere and charged stabilized colloids.\nIn this work, using hard-core repulsive Yukawa model, which is known to show\ncomplex phase behavior consisting of fluid, FCC and BCC phases, we studied the\ninterplay between the free energy landscape and polymorph selection during\ncrystallization. When the stability of the BCC phase with respect to the fluid\nphase is gradually increased by changing the temperature and pressure at a\nfixed fluid-FCC stability, the final phase formed by crystallization is found\nto undergo a switch from the FCC to the BCC phase, even though FCC remains\nthermodynamically the most stable phase. We further show that the nature of\nlocal bond-orientational order parameter fluctuations in the metastable fluid\nphase as well as the composition of the critical cluster depend delicately on\nthe free energy landscape, and play a decisive role in the polymorph selection\nduring crystallization.",
        "positive": "Monte Carlo procedure for protein folding in lattice model.\n  Conformational rigidity: A rigourous Monte Carlo method for protein folding simulation on lattice\nmodel is introduced. We show that a parameter which can be seen as the rigidity\nof the conformations has to be introduced in order to satisfy the detailed\nbalance condition. Its properties are discussed and its role during the folding\nprocess is elucidated. This method is applied on small chains on\ntwo-dimensional lattice. A Bortz-Kalos-Lebowitz type algorithm which allows to\nstudy the kinetic of the chains at very low temperature is implemented in the\npresented method. We show that the coefficients of the Arrhenius law are in\ngood agreement with the value of the main potential barrier of the system."
    },
    {
        "anchor": "Composition dependence of the glass forming ability in binary mixtures:\n  The role of demixing entropy: We present a comparative study of the glass forming ability of binary systems\nwith varying composition, where the systems have similar global crystalline\nstructure (CsCl+fcc). Biased Monte Carlo simulations using umbrella sampling\ntechnique shows that the free energy cost to create a CsCl nucleus increases as\nthe composition of the smaller particles are decreased. We find that the\nsystems with comparatively lower free energy cost to form CsCl nucleus exhibit\nmore pronounced pre-crystalline demixing near the liquid/crystal interface. The\nstructural frustration between the CsCl and fcc crystal demands this demixing.\nWe show that closer to the equimolar mixture the entropic penalty for demixing\nis lower and a glass forming system may crystallize spontaneously when seeded\nwith a nucleus. This entropic penalty as a function of composition shows a\nnon-monotonic behavior with a maximum at a composition similar to the well\nknown Kob-Anderson (KA) model. Although the KA model shows the maximum entropic\npenalty and thus maximum frustration against CsCl formation, it also shows a\nstrong tendency towards crystallization into fcc lattice of the larger \"A\"\nparticles which can be explained from the study of the energetics. Thus for\nsystems closer to the equimolar mixture although it is the requirement of\ndemixing which provides their stability against crystallization, for KA model\nit is not demixing but slow dynamics and structural frustration caused by the\nlocally favored structure around the smaller \"B\" particles which make it a good\nglass former. Although the glass forming binary systems studied here are quite\nsimilar, differing only in composition, we find that their glass forming\nability cannot be attributed to a single phenomena.",
        "positive": "Memory in Non-Monotonic Stress Response of an Athermal Disordered Solid: Athermal systems across a large range of length scales, ranging from foams\nand granular bead packings to crumpled metallic sheets, exhibit slow stress\nrelaxation when compressed. Experimentally they show a non-monotonic stress\nresponse when decompressed somewhat after an initial compression, i.e. under a\ntwo-step, Kovacs-like protocol. It turns out that from this response one can\ntell for how long the system was in a compressed state, suggesting an\ninterpretation as a memory effect. In this work we use a model of an athermal\njammed solid, specifically a binary mixture of soft harmonic particles, to\nexplore this phenomenon through in-silico experiments. Using extensive\nsimulations under conditions analogous to those in experiment, we observe\nidentical phenomenology in the stress response under a two-step protocol. Our\nmodel system also recovers the behaviour under a more recently studied\nthree-step protocol, which consists of a compression followed by a\ndecompression and then a final compression. We show that the observed response\nin both two-step and three-step protocols can be understood using Linear\nResponse Theory. In particular, a linear scaling with age for the two-step\nprotocol arises generically for slow linear responses with power law or\nlogarithmic decay and does not in itself point to any underlying aging\ndynamics."
    },
    {
        "anchor": "Flow-deformed conformations of entangled polymers as persistent random\n  walks: Evolving structure and rheology across Kuhn scale interfaces in entangled\npolymer fluids under flow play a prominent role in processing of manufactured\nplastics, and have numerous other applications. Quantitative tracking of chain\nconformation statistics on the Kuhn scale is essential for developing\ncomputational models of such phenomena. For this purpose, we formulate here a\ntwo-scale/two-mode model of entangled polymer chains under flow. Each chain is\npartitioned by successive entanglements into strands that are in one of two\nmodes: entangled or dangling. On the strand scale, conformation statistics of\nideal (non-interacting) strands follows a differential evolution equation for\nthe second moment of its end-to-end distance. The latter regulates persistent\nrandom walks sampling conformation statistics of ideal entangled strands on the\nKuhn scale, as follows from a generalized Green-Kubo relation and the Maximum\nEntropy Principle. We test it numerically for a range of deformation rates at\nthe start-up of simple elongational and shear flows. A self-consistent\npotential, representing segmental interactions, modifies strand conformation\nstatistics on the Kuhn scale, as it renormalizes the parameters controlling the\npersistent random walk. The generalized Green-Kubo relation is then inverted to\ndetermine how the second moment of the strand end-to-end distance is changed by\nthe self-consistent potential. This allows us to devise a two-scale propagation\nscheme for the statistical weights of subchains of the entangled chain. The\nlatter is used to calculate local volume fractions for each chemical type of\nKuhn segments in entangled chains, thus determining the self-consistent\npotential.",
        "positive": "The packing of granular polymer chains: Rigid particles pack into structures, such as sand dunes on the beach, whose\noverall stability is determined by the average number of contacts between\nparticles. However, when packing spatially extended objects with flexible\nshapes, additional concepts must be invoked to understand the stability of the\nresulting structure. Here we study the disordered packing of chains constructed\nout of flexibly-connected hard spheres. Using X-ray tomography, we find long\nchains pack into a low-density structure whose mechanical rigidity is mainly\nprovided by the backbone. On compaction, randomly-oriented, semi-rigid loops\nform along the chain, and the packing of chains can be understood as the\njamming of these elements. Finally we uncover close similarities between the\npacking of chains and the glass transition in polymers."
    },
    {
        "anchor": "Lattice Boltzmann simulations of self-propelling chiral active droplets: Active matter describes materials whose constituents are driven out of\nequilibrium by continuous energy consumption, for instance from ATP. Due to the\norientable character of the constituents, active suspensions can attain liquid\ncrystalline order and can be theoretically described as active liquid crystals.\nTheir inherently nonequilibrium dynamics causes a range of new striking\neffects, that in most cases have been characterized with numerical simulations,\nusing lattice Boltzmann models (LB). In many active biological systems\nchirality plays an important role. Biomolecules such as DNA, actin, or\nmicrotubules form helical structures which, at sufficiently high density and in\nthe absence of active forces, tend to self-assemble into twisted cholesteric\nphases. Understanding the outcome of the interplay between chirality and\nactivity is therefore an important and timely question. Studying a droplet of\nchiral matter in 3D, we have found evidence of a new motility mode, where the\nrotational motion of surface topological defects, that arrange in a fan-like\npattern. The resulting regular propulsive motion due to the underlying\nchirality is a striking phenomenon that can be also used in practical\napplications. The use of a parallel (MPI) implementation of lattice Boltzmann\nmodels, and available HPC resources, have been of fundamental importance in\nconducting the study. We have used different HPC clusters and among these\nRECAS. This allowed us to conduct a scaling test performed on different\ncomputational infrastructures.",
        "positive": "Criticality and mechanical enhancement in composite fibre networks: Many biological materials consist of sparse networks of disordered fibres,\nembedded in a soft elastic matrix. The interplay between rigid and soft\nelements in such composite networks leads to mechanical properties that can go\nfar beyond the sum of those of the constituents. Here we present lattice-based\nsimulations to unravel the microscopic origins of this mechanical synergy. We\nshow that the competition between fibre stretching and bending and elastic\ndeformations of the matrix gives rise to distinct mechanical regimes, with\nphase transitions between them that are characterized by critical behaviour and\ndiverging strain fluctuations and with different mechanisms leading to\nmechanical enhancement."
    },
    {
        "anchor": "Note: Brownian motion of colloidal particles of arbitrary shape: The analytical expressions for the time-dependent cross-correlations of the\ntranslational and rotational Brownian displacements of a particle with\narbitrary shape are derived. The reference center is arbitrary, and the\nreference frame is such that the rotational-rotational diffusion tensor is\ndiagonal.",
        "positive": "Modeling the diffusion of a fluid in a strained solid: a comparison\n  between different formats: We revise the format proposed by Bowen in [R.~M. Bowen. Int. J. Eng. Sci.,\n18(9):1129--1148, 1980.] to describe incompressible porous media by use of the\ntheory of mixtures. We then show that this format is equivalent the those\nproposed more recently to model the diffusion of a fluid in a strained solid."
    },
    {
        "anchor": "Fractional defect charges in $p$-atic liquid crystals on cones: Conical surfaces, with a delta function of Gaussian curvature at the apex,\nare perhaps the simplest example of geometric frustration. We study\ntwo-dimensional liquid crystals with $p$-fold rotational symmetry ($p$-atics)\non the surfaces of cones. For free boundary conditions at the base, we find\nboth the ground state(s) and a discrete ladder of metastable states as a\nfunction of both the cone angle and the liquid crystal symmetry $p$. We find\nthat these states are characterized by a set of fractional defect charges at\nthe apex and that the ground states are in general frustrated due to effects of\nparallel transport along the azimuthal direction of the cone. We check our\npredictions for the ground state energies numerically for a set of commensurate\ncone angles (corresponding to a set of commensurate Gaussian curvatures\nconcentrated at the cone apex), whose surfaces can be polygonized as a perfect\ntriangular or square mesh, and find excellent agreement with our theoretical\npredictions.",
        "positive": "Direct numerical simulations for non-Newtonian rheology of concentrated\n  particle dispersions: The non-Newtonian behavior of a monodisperse concentrated dispersion of\nspherical particles was investigated using a direct numerical simulation\nmethod, that takes into account hydrodynamic interactions and thermal\nfluctuations accurately. Simulations were performed under steady shear flow\nwith periodic boundary conditions in the three directions. The apparent shear\nviscosity of the dispersions was calculated at volume fractions ranging from\n0.31 to 0.56. Shear-thinning behavior was clearly observed at high volume\nfractions. The low- and high-limiting viscosities were then estimated from the\napparent viscosity by fitting these data into a semi-empirical formula.\nFurthermore, the short-time motions were examined for Brownian particles\nfluctuating in concentrated dispersions, for which the fluid inertia plays an\nimportant role. The mean square displacement was monitored in the vorticity\ndirection at several different Peclet numbers and volume fractions so that the\nparticle diffusion coefficient is determined from the long-time behavior of the\nmean square displacement. Finally, the relationship between the non-Newtonian\nviscosity of the dispersions and the structural relaxation of the dispersed\nBrownian particles is examined."
    },
    {
        "anchor": "Contact transience during slow loading of dense granular materials: The irregularity of particle motions during quasi-static deformation is\ninvestigated using discrete element (DEM) simulations of sphere and\nsphere-cluster assemblies. A total of three types of interparticle movements\nare analyzed: relative motions of particle centers, relative motions of\nmaterial points of two particles at their contact, and the traversal of\ncontacts across the surfaces of particles. Motions are a complex combination of\nrolling, sliding, and elastic distortion at the contacts, and all motions are\nhighly irregular and variant, qualities that increase with increasing strain.\nThe relative motions of particle centers diverge greatly from those of an\naffine displacement of the particles. The motions of the nonconvex\nsphere-cluster particles were more regular that those of the spheres. The paper\nalso investigates the effect of the distance between two remote particles and\ntheir pair-wise relative displacements. Even for particle pairs separated by\nmore than six intermediate particles, the relative motions do not conform with\nthe mean deformation (affine) field. Force chains are shown to be transient\nfeatures, which survive only briefly across elapsed strains.",
        "positive": "Chiral photonic crystals from sphere packing: Inspired by recent developments in self-assembled chiral nanostructures, we\nhave explored the possibility of using spherical particles packed in cylinders\nas building blocks for chiral photonic crystals. In particular, we focused on\nan array of parallel cylinders arranged in a perfect triangular lattice, each\ncontaining an identical densest sphere packing structure. Despite the\nnon-chirality of both the spheres and cylinders, the self-assembled system can\nexhibit chirality due to spontaneous symmetry breaking during the assembly\nprocess. We have investigated the circular dichroism effects of the system and\nhave found that, for both perfect electric conductor and dielectric spheres,\nthe system can display dual-polarization photonic band gaps for circularly\npolarized light at normal incidence along the axis of the helix. Further, we\nhave examined how the polarization band gap size depends on the dielectric\nconstant of the spheres and the packing fraction of the cylinders. Our study\nsuggests that a cluster formed by spheres self-assembling inside parallel\ncylinders with appropriate material parameters can be a promising approach to\ncreating chiral photonic crystals."
    },
    {
        "anchor": "Discrete element simulations of stress distributions in silos: crossover\n  from two to three dimensions: The transition from two-dimensional (2D) to three-dimensional (3D) granular\npackings is studied using large-scale discrete element computer simulations. We\nfocus on vertical stress profiles and examine how they change with\ndimensionality from 2D to 3D. We compare results for packings in 2D, quasi-2D\npackings between flat plates, and 3D packings. Analysis of these packings\nsuggests that the Janssen theory does not fully describe these packings,\nespecially at the top of the piles, where a hydrostatic-like region of vertical\nstress is visible in all cases. We find that the interior of the packing is far\nfrom incipient failure, while in general, the forces at the walls are close to\nincipient failure.",
        "positive": "Shape Allophiles Improve Entropic Assembly: We investigate a class of \"shape allophiles\" that fit together like puzzle\npieces as a method to access and stabilize desired structures by controlling\ndirectional entropic forces. Squares are cut into rectangular halves, which are\nshaped in an allophilic manner with the goal of re-assembling the squares while\nself-assembling the square lattice. We examine the assembly characteristics of\nthis system via the potential of mean force and torque, and the fraction of\nparticles that entropically bind. We generalize our findings and apply them to\nself-assemble triangles into a square lattice via allophilic shaping. Through\nthese studies we show how shape allophiles can be useful in assembling and\nstabilizing desired phases with appropriate allophilic design."
    },
    {
        "anchor": "Isomorph theory beyond thermal equilibrium: This paper generalizes isomorph theory to systems that are not in thermal\nequilibrium. The systems are assumed to be R-simple, i.e., have a potential\nenergy that as a function of all particle coordinates $\\textbf{R}$ obeys the\nhidden-scale-invariance condition $U(\\textbf{R}_{\\rm a})<U(\\textbf{R}_{\\rm\nb})\\Rightarrow U(\\lambda\\textbf{R}_{\\rm a})<U(\\lambda\\textbf{R}_{\\rm b})$.\n\"Systemic isomorphs\" are introduced as lines of constant excess entropy in the\nphase diagram defined by density and systemic temperature, which is the\ntemperature of the equilibrium state point with average potential energy equal\nto $U(\\textbf{R})$. The dynamics is invariant along a systemic isomorph if\nthere is a constant ratio between the systemic and the bath temperature. In\nthermal equilibrium, the systemic temperature is equal to the bath temperature\nand the original isomorph formalism is recovered. The new approach rationalizes\nwithin a consistent framework previously published observations of isomorph\ninvariance in simulations involving nonlinear steady-state shear flows,\nzero-temperature plastic flows, and glass-state isomorphs. The paper relates\nbriefly to granular media, physical aging, and active matter. Finally, we\ndiscuss the possibility that the energy unit defining reduced quantities should\nbe based on the systemic rather than the bath temperature.",
        "positive": "First order alignment transition in an interfaced active nematic: We investigate experimentally the dynamic phase transition of a\ntwo-dimensional active nematic layer interfaced with a passive liquid crystal.\nUnder a temperature ramp that leads to the transition of the passive liquid\ninto a highly anisotropic lamellar smectic-A phase, and in the presence of a\nmagnetic field, the coupled active nematic reorganizes its flow and\norientational patterns from the turbulent into a quasi-laminar regime aligned\nperpendicularly to the field. Remarkably, while the phase transition of the\npassive fluid is known to be continuous, our observations reveal intermittent\ndynamics of the order parameter and the coexistence of aligned and turbulent\nregions in the active nematic, a signature of discontinuous, or first order,\nphase transitions."
    },
    {
        "anchor": "Motion of a condensate in a shaken and vibrating harmonic trap: The dynamics of a Bose-Einstein condensate (BEC) in a time-dependent harmonic\ntrapping potential is determined for arbitrary variations of the position of\nthe center of the trap and its frequencies. The dynamics of the BEC wavepacket\nis soliton-like. The motion of the center of the wavepacket, and the spatially\nand temporally dependent phase (which affects the coherence properties of the\nBEC) multiplying the soliton-like part of the wavepacket, are analytically\ndetermined.",
        "positive": "A stochastic model for directional changes of swimming bacteria: In this work we introduce a stochastic model to describe directional changes\nin the movement of swimming bacteria. We use the probability density function\n(PDF) of turn angles, measured on tumbling wild-type {\\it E. coli}, to build a\nLangevin equation for the deflection of the bacterial body swimming in\nisotropic media. We have solved this equation analytically by means of the\nGreen function method and shown that three parameters are sufficient to\ndescribe the movement: the characteristic time, the steady-state solution and\nthe control parameter. We conclude that the tumble motion, which is manifested\nas abrupt turns, is primarily caused by the rotational boost generated by the\nflagellar motor and complementarily by the rotational diffusion introduced by\nnoise. We show that in the tumble motion the deflection is a non-stationary\nstochastic process during times at which the tumbling occurs. By tuning the\ncontrol parameter our model is able to explain small turns of the bacteria\naround their centres of mass along the run. We show that the deflection during\nthe run is an OrnsteinUhlenbeck process, which for typical run times is\nstationary. We conclude that, along the run, the rotational boosts do not exist\nand that only the rotational diffusion remains. Thus we have a single model to\nexplain the turns of through a critical value that can explain the transition\nbetween the two turn behaviours. This model is the bacterium during the run or\ntumble movements, through a control parameter that can be tuned also able to\nexplain in a very satisfactory way all available statistical experimental data,\nsuch as PDFs and average values of turning angles times, of both run and tumble\nmotions."
    },
    {
        "anchor": "Phase Diagram of Flexible Polymers with Quenched Disordered Charged\n  Monomers: Recent advances in Generalized Ensemble simulations and microcanonical\nanalysis allowed the investigation of structural transitions in polymer models\nover a broad range of local bending and torsion strengths. It is reasonable to\nargue that electrostatic interactions play a significant role in stabilizing\nand mediating structural transitions in polymers. We propose a bead-spring\npolymer model with randomly distributed charged monomers interacting via a\nscreened Coulomb potential. By combining the Replica Exchange Wang-Landau\n(REWL) method with energy-dependent monomer updates, we constructed the\nhyperphase diagram as a function of temperature ($T$) and charged monomer\nconcentration ($\\eta$). The coil-globule and globular-solid transitions are\nrespectively second and first order for the entire concentration range.\nHowever, above a concentration threshold of $\\eta=80\\%$, electrostatic\nrepulsion hinders the formation of solid and liquid globules, and the interplay\nbetween enthalpic and entropic interactions leads to the formation of liquid\npearl-necklace ad solid helical structures. The probability distribution,\n$P(E,T)$, indicates that at high $\\eta$, the pearl-necklace liquid phase\nfreezes into a stable solid helix-like structure with a free energy barrier\nhigher than the freezing globule transition at low $\\eta$.",
        "positive": "Spreading of triboelectrically charged granular matter: We report on the spreading of triboelectrically charged glass particles on an\noppositely charged surface of a plastic cylindrical container in the presence\nof a constant mechanical agitation. The particles spread via sticking, as a\nmonolayer on the cylinder's surface. Continued agitation initiates a sequence\nof instabilities of this monolayer, which first forms periodic\nwavy-stripe-shaped transverse density modulation in the monolayer and then\nejects narrow and long particle-jets from the tips of these stripes. These jets\nfinally coalesce laterally to form a homogeneous spreading front that is\nlayered along the spreading direction. These remarkable growth patterns are\nrelated to a time evolving frictional drag between the moving charged glass\nparticles and the countercharges on the plastic container. The results provide\ninsight into the multiscale time-dependent tribolelectric processes and\nmotivates further investigation into the microscopic causes of these\nmacroscopic dynamical instabilities and spatial structures."
    },
    {
        "anchor": "Hydrodynamics of quartz crystal microbalance experiments with\n  liposome-DNA complexes: The quartz crystal microbalance (QCM) is widely used to study surface\nadsorbed molecules, often of biological significance. However, the relation\nbetween raw acoustic response (frequency shift $\\Delta f$ and dissipation\nfactor $\\Delta D$) and mechanical properties of the macromolecules still needs\nto be deciphered, particularly in the case of suspended discrete particles. We\nstudy the QCM response of suspended liposomes tethered to the resonator wall by\ndouble stranded DNA, with the other end attached to surface-adsorbed\nneutravidin through a biotin linker. Liposome radius and dsDNA contour length\nare comparable to the wave penetration depth ($\\delta\\sim 100\\ \\mathrm{nm}$).\nSimulations, based on the immersed boundary method and an elastic network model\nfor the liposome-DNA complex, are in good agreement with experimental results\nfor POPC liposomes. We find that the added stress at the resonator surface,\ni.e. the impedance Z sensed by QCM, is dominated by the flow-induced liposome\nsurface-stress, which propagates towards the resonator by viscous forces. QCM\nsignals are extremely sensitive to the liposome's height distribution P(y)\nwhich depends on the actual number and mechanical properties of the tethers, in\naddition to the usual local attractive/repulsive chemical forces. Our approach\nhelps in deciphering the role of hydrodynamics in acoustic sensing and\nrevealing the role of parameters hitherto largely unexplored. A practical\nconsequence would be the design of improved biosensors and detection schemes.",
        "positive": "The Shape and Motion of a Ruck in a Rug: The motion of a ruck in a rug is used as an analogy to explain the role of\ndislocations in the deformation of crystalline solids. We take the analogy\nliterally and study the shape and motion of a bump, wrinkle or ruck in a thin\nsheet in partial contact with a rough substrate in a gravitational field. Using\na combination of experiments, scaling analysis and numerical solutions of the\ngoverning equations, we first quantify the static shape of a ruck on a\nhorizontal plane. When the plane is inclined, the ruck becomes asymmetric and\nmoves by rolling only when the the inclination of the plane reaches a critical\nangle. We find that the angle at which this first occurs is larger than the\nangle at which the ruck stops, i.e. static rolling friction is larger than\ndynamic rolling friction. Once the ruck is in motion, it travels at a constant\nspeed proportional to the sine of the angle of inclination, a result that we\nrationalize in terms of a simple power balance. We conclude with a simple\nimplication of our study for the onset of rolling motion at soft interfaces."
    },
    {
        "anchor": "Linking particle dynamics to local connectivity in colloidal gels: Colloidal gels are a prototypical example of a heterogeneous network solid\nwhose complex properties are governed by thermally-activated dynamics. In this\nLetter we experimentally establish the connection between the intermittent\ndynamics of individual particles and their local connectivity. We interpret our\nexperiments with a model that describes single-particle dynamics based on\nhighly cooperative thermal debonding. The model, in quantitative agreement with\nexperiments, provides a microscopic picture for the structural origin of\ndynamical heterogeneity in colloidal gels and sheds new light on the link\nbetween structure and the complex mechanics of these heterogeneous solids.",
        "positive": "Dynamical Majorana Edge Modes in a Broad Class of Topological Mechanical\n  Systems: Mechanical systems can display topological characteristics similar to that of\ntopological insulators. Here we report a large class of topological mechanical\nsystems related to the BDI symmetry class. These are self-assembled chains of\nrigid bodies with an inversion center and no reflection planes. The\nparticle-hole symmetry characteristic to the BDI symmetry class stems from the\ndistinct behavior of the translational and rotational degrees of freedom under\ninversion. This and other generic properties led us to the remarkable\nconclusion that, by adjusting the gyration radius of the bodies, one can always\nsimultaneously open a gap in the phonon spectrum, lock-in all the\ncharacteristic symmetries and generate a non-trivial topological invariant. The\nparticle-hole symmetry occurs around a finite frequency, hence we can witness a\ndynamical topological Majorana edge mode. Contrasting a floppy mode occurring\nat zero frequency, a dynamical edge mode can absorb and store mechanical\nenergy, potentially opening new applications of topological mechanics."
    },
    {
        "anchor": "Wrinkles in soft dielectric plates: We show that a smooth giant voltage actuation of soft dielectric plates is\nnot easily obtained in practice. In principle one can exploit, through\npre-deformation, the snap-through behavior of their loading curve to deliver a\nlarge stretch prior to electric breakdown. However, we demonstrate here that\neven in this favorable scenario, the soft dielectric is likely to first\nencounter the plate wrinkling phenomenon, as modeled by the onset of\nsmall-amplitude sinusoidal perturbations on its faces. We provide an explicit\ntreatment of this incremental boundary value problem. We also derive\nclosed-form expressions for the two limit cases of very thin membranes (with\nvanishing thickness) and of thick plates (with thickness comparable to or\ngreater than the wavelength of the perturbation). We treat explicitly examples\nof ideal dielectric free energy functions (where the mechanical part is of the\nneo-Hookean, Mooney-Rivlin or Gent form) and of dielectrics exhibiting\npolarization saturation. Finally we make the link with the classical results of\nthe Hessian electro-mechanical instability criterion and of Euler buckling for\nan elastic column.",
        "positive": "Counterion Condensation in Strong, Flexible Polyelectrolytes: We present results of molecular dynamics simulations of strong, flexible\npolyelectrolyte chains in solution with added salt. The effect of added salt on\nthe polyelectrolyte chain structure is fully treated for the first time as a\nfunction of polymer density. Systems above and below the Manning condensation\nlimit are studied. The chain contraction due to added salt is weaker than\nexpected from simple screening arguments. The chain structure is intimately\ntied to the ion density near the chain even for chains in the counterion\ncondensation regime. In contradiction to Manning counterion condensation\ntheory, the ion density near the polymer chain depends on the amount of added\nsalt, and above the condensation limit the chains significantly contract due to\nadded salt."
    },
    {
        "anchor": "Dual free energies in Poisson-Boltzmann theory: Poisson-Boltzmann theory allows one to study soft matter and biophysical\nsystems involving point-like charges of low valencies. The inclusion of\nfluctuation corrections beyond the mean-field approach typically requires the\napplication of loop expansions around a mean-field solution for the\nelectrostatic potential \\(\\phi({\\bf r})\\), or sophisticated variational\napproaches. Recently, Poisson-Boltzmann theory has been recast, via a Legendre\ntransform, as a mean-field theory involving the dielectric displacement field\n\\({\\bf D}({\\bf r})\\). In this paper we consider the path integral formulation\nof the dual theory. Exploiting the transformation between \\(\\phi\\) and \\({\\bf\nD}\\), we formulate a dual Sine-Gordon field theory in terms of the displacement\nfield and provide a strategy for precise numerical computations of free\nenergies beyond the leading order.",
        "positive": "Spreading dynamics of reactive surfactants driven by Marangoni\n  convection: We consider the spreading dynamics of some insoluble surface-active species\nalong an aqueous interface. The model includes both diffusion, Marangoni\nconvection and first-order reaction kinetics. An exact solution of the\nnonlinear transport equations is derived in the regime of large Schmidt number,\nwhere viscous effects are dominant. We demonstrate that the variance of the\nsurfactant distribution increases linearly with time, providing an unambiguous\ndefinition for the enhanced diffusion coefficient observed in the experiments.\nThe model thus presents new insight regarding the actuation of camphor grains\nat the water-air interface."
    },
    {
        "anchor": "Gap solitons in quasiperiodic optical lattices: Families of solitons in one- and two-dimensional (1D and 2D) Gross-Pitaevskii\nequations with the repulsive nonlinearity and a potential of the\nquasicrystallic type are constructed (in the 2D case, the potential corresponds\nto a five-fold optical lattice). Stable 1D solitons in the weak potential are\nexplicitly found in three bandgaps. These solitons are mobile, and they collide\nelastically. Many species of tightly bound 1D solitons are found in the strong\npotential, both stable and unstable (unstable ones transform themselves into\nasymmetric breathers). In the 2D model, families of both fundamental and\nvortical solitons are found and are shown to be stable.",
        "positive": "Pattern formation in colloidal mixtures under external driving fields: The influence of an external field acting differently on the two constituents\nof a binary colloidal mixture performing Brownian dynamics is investigated by\ncomputer simulations and a simple theory. In our model, one half of the\nparticles ($A$-particles) are pulled by an external force ${\\vec F}^{(A)}$\nwhile the other half of them ($B$-particles) are pulled by an external force\n${\\vec F}^{(B)}$. If ${\\vec F}^{(A)}$ and ${\\vec F}^{(B)}$ are parallel and the\nfield-free state is a mixed fluid, previous simulations (J. Dzubiella et al,\nPhys. Rev. E {\\bf 65} 021402 (2002)) have shown a nonequilibrium pattern\nformation involving lanes of $A$ or $B$ particles only which are sliding\nagainst each other in the direction of the external forces. In this paper, we\ngeneralize the situation both to non-parallel external forces and to field-free\ncrystalline states. For non-parallel forces, lane formation is also observed\nbut with an orientation {\\it tilted} with respect to the external forces. If\nthe field-free state is crystalline, a continuous increase of the parallel\nexternal forces yields a novel {\\it reentrant freezing} behavior: the crystal\nfirst melts mechanically via the external force and then recrystallizes into\ndemixed crystalline lanes sliding against each other."
    },
    {
        "anchor": "Mesoscale Structure of Chiral Nematic Shells: There is considerable interest in understanding and controlling topological\ndefects in nematic liquid crystals (LCs). Confinement, in the form of droplets,\nhas been particularly effective in that regard. Here, we employ the Landau-de\nGennes method to explore the geometrical frustration of nematic order in shell\ngeometries, and focus on chiral materials. By varying the chirality and\nthickness in uniform shells, we construct a phase diagram that includes\ntetravalent structures, bipolar structures (BS), bent structures and radial\nspherical structures (RSS). It is found that, in uniform shells, the BS-to-RSS\nstructural transition, in response to both chirality and shell geometry, is\naccompanied by an abrupt change of defect positions, implying a potential use\nfor chiral nematic shells as sensors. Moreover, we investigate thickness\nheterogeneity in shells and demonstrate that non-chiral and chiral nematic\nshells exhibit distinct equilibrium positions of their inner core that are\ngoverned by shell chirality c.",
        "positive": "Left or right cholesterics? A matter of helix handedness and curliness: We have investigated the relationship between the morphology of helical\nparticles and the features of the cholesteric (N$^\\ast $) phase that they form.\nUsing an Onsager-like theory, applied to systems of hard helices, we show that\nthe cholesteric handedness and pitch depend on both the pitch and the curliness\nof the particles. The theory leads to the definition of pseudoscalars that\ncorrelate the helical features of the phase to the chirality of the excluded\nvolume of the constituent particles."
    },
    {
        "anchor": "Two-species mixture of quantum degenerate Bose and Fermi gases: We have produced a macroscopic quantum system in which a Li-6 Fermi sea\ncoexists with a large and stable Na-23 Bose-Einstein condensate. This was\naccomplished using inter-species sympathetic cooling of fermionic Li-6 in a\nthermal bath of bosonic Na-23.",
        "positive": "Some results on finite amplitude elastic waves propagating in rotating\n  media: Two questions related to elastic motions are raised and addressed. First: in\nwhich theoretical framework can the equations of motion be written for an\nelastic half-space put into uniform rotation? It is seen that nonlinear finite\nelasticity provides such a framework for incompressible solids. Second: how can\nfinite amplitude exact solutions be generated? It is seen that for some finite\namplitude transverse waves in rotating incompressible elastic solids with\ngeneral shear response, the solutions are obtained by reduction of the\nequations of motion to a system of ordinary differential equations equivalent\nto the system governing the central motion problem of classical mechanics. In\nthe special case of circularly-polarized harmonic progressive waves, the\ndispersion equation is solved in closed form for a variety of shear responses,\nincluding nonlinear models for rubberlike and soft biological tissues. A\nfruitful analogy with the motion of a nonlinear string is pointed out."
    },
    {
        "anchor": "First passage time and information of a one-dimensional Brownian\n  particle with stochastic resetting to random positions: We explore the effects of stochastic resetting to random positions of a\nBrownian particle on first passage times and Shannon's entropy. We explore the\ndifferent entropy regimes, namely, the \\textit{externally-driven}, the\n\\textit{zero-entropy} and the \\textit{Maxwell demon} regimes. We show that the\nmean first passage time (MPFT) minimum can be found in any of these regimes. We\nprovide a novel analytical method to compute the MFPT, the mean first passage\nnumber of resets (MFPNR) and mean first passage entropy (MFPE) in the case\nwhere the Brownian particle resets to random positions sampled from a set of\ndistributions known \\textit{a priori}. We show the interplay between the reset\nposition distribution's second moment and the reset rate, and the effect it has\non the MFPT and MFPE. We further propose a mechanism whereby the entropy per\nreset can be either in the Maxwell demon or the externally driven regime, yet\nthe overall mean first passage entropy corresponds to the zero-entropy regime.\nAdditionally, we find an overlap between the dynamic phase space and the\nentropy phase space. We use this method in a generalized version of the\nEvans-Majumdar model by assuming the reset position is random and sampled from\na Gaussian distribution. We then consider the \\textit{toggling reset} whereby\nthe Brownian particle resets to a random position sampled from a distribution\ndependent on the reset parity. All our results are compared to and in agreement\nwith numerical simulations.",
        "positive": "Nonlinear Poisson effect governed by mechanical critical transition: Under extensional strain, fiber networks can exhibit an anomalously large and\nnonlinear Poisson effect accompanied by a dramatic transverse contraction and\nvolume reduction for applied strains as small as a few percent. We demonstrate\nthat this phenomenon is controlled by a collective mechanical phase transition\nthat occurs at a critical uniaxial strain that depends on network connectivity.\nThis transition is punctuated by an anomalous peak in the apparent Poisson's\nratio and other critical signatures such as diverging nonaffine strain\nfluctuations."
    },
    {
        "anchor": "Effective structure of a system with continuous polydispersity: In a system of N particles, with continuous size polydispersity there exists\nN(N-1) number of partial structure factors making it analytically less\ntractable. A common practice is to treat the system as an effective one\ncomponent system which is known to exhibit an artificial softening of the\nstructure. The aim of this study is to describe the system in terms of M pseudo\nspecies such that we can avoid this artificial softening but at the same time\nhave a value of M << N. We use potential energy and pair excess entropy to\nestimate an optimum number of species, M_{0}. We find that systems with\npolydispersity width, {\\Delta}{\\sigma}_{0} can be treated as a monodisperse\nsystem. We show that M_{0} depends on the degree and type of polydispersity and\nalso on the nature of the interaction potential, whereas, {\\Delta}{\\sigma}_{0}\nweakly depends on the type of the polydispersity, but shows a stronger\ndependence on the type of interaction potential. Systems with softer\ninteraction potential have a higher tolerance with respect to polydispersity.\nInterestingly, M_{0} is independent of system size, making this study more\nrelevant for bigger systems. Our study reveals that even 1% polydispersity\ncannot be treated as an effective monodisperse system. Thus while studying the\nrole of polydispersity by using the structure of an effective one component\nsystem care must be taken in decoupling the role of polydispersity from that of\nthe artificial softening of the structure.",
        "positive": "Transition from a dissipative to a quasi-elastic system of particles\n  with tunable repulsive interactions: A two-dimensional system of particles with tunable repulsive interactions is\nexperimentally investigated. Soft ferromagnetic particles are placed on a\nvibrating rough plate and vertically confined, so that they perform a\nhorizontal Brownian motion in a cell. When immersed in an external vertical\nmagnetic field, the particles become magnetised and thus interact according to\na dipolar repulsive law. As the amplitude of the magnetic field is increased,\nmagnetic repulsion raises and the rate of inelastic collisions decreases.\nStudying the pair correlation function and the particle velocity distributions,\nwe show that the typical properties of such a dissipative out-of-equilibrium\ngranular gas are progressively lost, to approach those expected for a usual gas\nat thermodynamic equilibrium. For stronger interaction strengths, the system\ngradually solidifies towards a hexagonal crystal. This new setup could\nconsequently be used as a model experimental system for out-of-equilibrium\nstatistical physics, in which the distance to the quasi-elastic limit can be\naccurately controlled."
    },
    {
        "anchor": "Two-dimensional Copolymers and Multifractality: Comparing Perturbative\n  Expansions, MC Simulations, and Exact Results: We analyze the scaling laws for a set of two different species of long\nflexible polymer chains joined together at one of their extremities (copolymer\nstars) in space dimension D=2. We use a formerly constructed field-theoretic\ndescription and compare our perturbative results for the scaling exponents with\nrecent conjectures for exact conformal scaling dimensions derived by a\nconformal invariance technique in the context of D=2 quantum gravity. A simple\nMC simulation brings about reasonable agreement with both approaches. We\nanalyse the remarkable multifractal properties of the spectrum of scaling\nexponents.",
        "positive": "Indentation responses of pressurized ellipsoidal and cylindrical elastic\n  shells: Insights from shallow-shell theory: Pressurized elastic shells are ubiquitous in nature and technology, from the\nouter walls of yeast and bacterial cells to artificial pressure vessels.\nIndentation measurements simultaneously probe the internal pressure and elastic\nproperties of thin shells, and serve as a useful tool for strength testing and\nfor inferring internal biological functions of living cells. We study the\neffects of geometry and pressure-induced stress on the indentation stiffness of\nellipsoidal and cylindrical elastic shells using shallow-shell theory. We show\nthat the linear indentation response reduces to a single integral with two\ndimensionless parameters that encode the asphericity and internal pressure.\nThis integral can be numerically evaluated in all regimes and is used to\ngenerate compact analytical expressions for the indentation stiffness in\nvarious regimes of technological and biological importance. Our results provide\ntheoretical support for previous scaling and numerical results describing the\nstiffness of ellipsoids, reveal a new pressure scale that dictates the\nlarge-pressure response, and give new insights to the linear indentation\nresponse of pressurized cylinders."
    },
    {
        "anchor": "Free Energy of Twisted Semiflexible Polymers: We investigate the role of fluctuations in single molecule measurements of\ntorque-link ($t-lk$) curves. For semiflexible polymers of finite persistence\nlength (i.e. polymers with contour length $L$ comparable to the persistence\nlength $L_P$), the torque versus link curve in the constant torque (isotorque)\nensemble is distinct from the one in the constant link (isolink) ensemble.\nThus, one encounters the conceptually interesting issue of a ``free energy of\ntransition'' in switching ensembles while making torque-link measurements. We\npredict the dependence on the semiflexibility parameter $\\beta = L/L_P$ of this\nextra contribution to the free energy which shows up as an area in the\ntorque-link plane. This can be tested against future torque-link experiments\nwith single biopolymers. We bring out the inequivalence of torque-link curves\nfor a stiff polymer and present explicit analytical expressions for the {\\it\ndistinct} torque-link relations in the two ensembles and the free energy\ndifference in switching ensembles in this context. The predictions of our work\ncan be tested against single molecule experiments on torsionally constrained\nbiopolymers.",
        "positive": "Coexistence of dilute and densely packed domains of ligand-receptor\n  bonds in membrane adhesion: We analyze the stability of micro-domains of ligand-receptor bonds that\nmediate the adhesion of biological model membranes. After evaluating the\neffects of membrane fluctuations on the binding affinity of a single bond, we\ncharacterize the organization of bonds within the domains by theoretical means.\nIn a large range of parameters, we find the commonly suggested dense packing to\nbe separated by a free energy barrier from a regime in which bonds are sparsely\ndistributed. If bonds are mobile, a coexistence of the two regimes should\nemerge, which agrees with recent experimental observations."
    },
    {
        "anchor": "Comment on 'Transient response of a wetting film to mechanical and\n  electrical perturbations': A comment on the recent paper of R Manica, J N Connor, L Y Clasohm, S L\nCarnie, R G Horn, D Y C Chan, Transient response of a wetting film to\nmechanical and electrical perturbations, Langmuir 2008, 24, 1381.",
        "positive": "Polydispersity and optimal relaxation in the hard sphere fluid: We consider the mass heterogeneity in a gas of polydisperse hard particles as\na key to optimizing a dynamical property: the kinetic relaxation rate. Using\nthe framework of the Boltzmann equation, we study the long time approach of a\nperturbed velocity distribution toward the equilibrium Maxwellian solution. We\nwork out the cases of discrete as well as continuous distributions of masses,\nas found in dilute fluids of mesoscopic particles such as granular matter and\ncolloids. On the basis of analytical and numerical evidence, we formulate a\ndynamical equipartition principle that leads to the result that no such\ncontinuous dispersion in fact minimizes the relaxation time, as the global\noptimum is characterized by a finite number of species. This optimal mixture is\nfound to depend on the dimension d of space, ranging from five species for d=1\nto a single one for d>=4. The role of the collisional kernel is also discussed,\nand extensions to dissipative systems are shown to be possible."
    },
    {
        "anchor": "Viscoelasticity of colloidal polycrystals doped with impurities: We investigate how the microstructure of a colloidal polycrystal influences\nits linear viscoelasticity. We use thermosensitive copolymer micelles that\narrange in water in a cubic crystalline lattice, yielding a colloidal\npolycrystal. The polycrystal is doped with a small amount of nanoparticles, of\nsize comparable to that of the micelles, which behave as impurities and thus\npartially segregate in the grain boundaries. We show that the shear elastic\nmodulus only depends on the packing of the micelles and does not vary neither\nwith the presence of nanoparticles nor with the crystal microstructure. By\ncontrast, we find that the loss modulus is strongly affected by the presence of\nnanoparticles. A comparison between rheology data and small-angle neutron\nscattering data suggests that the loss modulus is dictated by the total amount\nof nanoparticles in the grain boundaries, which in turn depends on the sample\nmicrostructure.",
        "positive": "Controlling breath figure patterns on PDMS by concentration variation of\n  ethanol-methanol binary vapors: In this paper, the self-assembly of condensed droplets on smooth and\nconstrained surfaces under saturated vapor atmosphere of ethanol and methanol\nbinary system is reported. Hexagonally ordered array of pores are obtained on\nsmooth surfaces with saturated vapors of binary liquids without the assistance\nof any additives. The results show that the addition of small amount of ethanol\nto methanol plays a role very similar to that of surface active agents in\ninducing the formation of regular droplet array. The effect of constraints on\nself-assembled droplet pattern such as movement of contact line and depinning\nof contact line is also investigated. It is observed that the pore size, pore\nshape, pore depth and ring diameter are influenced by the atmosphere of binary\nvapors in addition to the commonly held attribution to the surface tension of\nthe solvent. Contact angle studies of the patterned substrates showed\nhydrophobicity with very high adhesiveness to water and Wenzel's state of\nwetting."
    },
    {
        "anchor": "Dissipation indicates memory formation in driven disordered systems: Disordered and amorphous materials often retain memories of perturbations\nthey have experienced since preparation. Studying such memories is a gateway to\nunderstanding this challenging class of systems, yet it often requires the\nability to measure local structural changes in response to external drives.\nHere we show that dissipation is a generic macroscopic indicator for the memory\nof the largest perturbation. Through experiments in crumpled sheets under\ncyclic drive, we show that dissipation transiently increases when first\nsurpassing the largest perturbation due to irreversible structural changes with\nunique statistics. This is used to devise novel memory readout protocols based\non global observables only. The general applicability of this approach is\ndemonstrated by revealing a similar memory effect in a three-dimensional\namorphous solid.",
        "positive": "Assembling Ellipsoidal Particles at Fluid Interfaces using Switchable\n  Dipolar Capillary Interactions: The fabrication of novel soft materials is an important scientific and\ntechnological challenge. We investigate the response of magnetic ellipsoidal\nparticles adsorbed at fluid-fluid interfaces to external magnetic fields. By\nexploiting previously discovered first-order orientation phase transitions we\nshow how to switch on and off dipolar capillary interactions between particles,\nleading to the formation of distinctive self-assembled structures and allowing\ndynamic control of the bottom-up fabrication of reconfigurable novel-structured\nmaterials"
    },
    {
        "anchor": "Reentrant spinodals and the Speedy scenario in colloidal model systems: A re-entrant gas-liquid spinodal was proposed as a possible explanation of\nthe apparent divergence of the compressibility and specific heat on\nsupercooling water. Such a counter intuitive possibility, e.g. a liquid that\nbecomes unstable to gas-like fluctuations on cooling at positive pressure, has\nnever been observed, neither in real substances nor in off-lattice simulations.\nMore recently, such re-entrant scenario has been dismissed on the premise that\nthe re-entrant spinodal would collide with the gas-liquid binodal in the\npressure-temperature plane. Here we study, numerically and analytically, two\npreviously introduced one-component patchy particle models that both show (i) a\nre-entrant spinodal and (ii) a re-entrant binodal, providing a neat in silico\n(and in charta) realization of such unconventional thermodynamic scenario.",
        "positive": "Creasing of an everted elastomer tube: A cylindrical elastomer tube can stay in an everted state without any applied\nexternal forces. If the thickness of the tube is small, the everted tube,\nexcept for the regions close to the two ends of the tube, is cylindrical, if\nthe thickness is larger than a critical value, the cross-section of the everted\ntube becomes noncircular, which is due to mechanical instability. Although the\neversion-induced mechanical instability in an elastomer tube has been reported\nseveral decades ago, a satisfying explanation of the phenomenon is still\nunavailable. In all previous studies, linear stability analyses have been\ncommonly adopted to predict the critical thickness of the tube for the\neversion-induced instability. The discrepancy between the prediction and\nexperiment is significant and well known. In this letter, based on the\nexperiments and theoretical analyses, we show that crease formation on the\ninner surface of an everted tube is the mechanical instability mode, which\ncannot be captured by linear stability analyses. Instead, a combination of\nenergetic analyses and numerical simulation of highly nonlinear deformation\nenables us to correctly predict both the critical thickness of the tube for the\nonset of creases and the profile of the cross-section of an everted tube with\nmultiple creases on its inner surface."
    },
    {
        "anchor": "Permeability anisotropy induced by a shear displacement: The permeability anisotropy that results from a shear displacement 'u'\nbetween the complementary self-affine walls of a rough fracture is\ninvestigated. Experiments in which a dyed fluid displaces a transparent one as\nit is radially injected into a transparent fracture exhibit a clear anisotropy\nin the presence of shear displacements, and allow us to estimate the ratio of\nthe permeabilities for flows parallel and perpendicular to 'u'. A simple model\nwhich accounts for the development of channels perpendicular to 'u'\nqualitatively explains these results, and predicts a permeability decreasing\n(increasing) linearly with the variance of the aperture field for flow parallel\n(perpendicular) to the shear displacement. These predictions are then compared\nto the results of numerical simulations performed using a lattice-Boltzmann\ntechnique and to the anisotropies measured in displacement experiments.",
        "positive": "Nonequilibrium thermodynamics of DNA nanopore unzipping: Using theory and simulations, we carried out a first systematic\ncharacterization of DNA unzipping via nanopore translocation. Starting from\npartially unzipped states, we found three dynamical regimes depending on the\napplied force, f: (i) heterogeneous DNA retraction and rezipping (f < 17pN),\n(ii) normal (17pN < f < 60pN) and (iii) anomalous (f > 60pN) drift-diffusive\nbehavior. We show that the normal drift-diffusion regime can be effectively\nmodelled as a one-dimensional stochastic process in a tilted periodic\npotential. We use the theory of stochastic processes to recover the potential\nfrom nonequilibrium unzipping trajectories and show that it corresponds to the\nfree-energy landscape for single base-pairs unzipping. Applying this general\napproach to other single-molecule systems with periodic potentials ought to\nyield detailed free-energy landscapes from out-of-equilibrium trajectories."
    },
    {
        "anchor": "Rigorous Proof of Pseudospin Ferromagnetism in Two-Component Bosonic\n  Systems with Component-Independent Interactions: For a two-component bosonic system, the components can be mapped onto a\npseudo-spin degree of freedom with spin quantum number S=1/2. We provide a\nrigorous proof that for a wide-range of real Hamiltonians with component\nindependent mass and interaction, the ground state is a ferromagnetic state\nwith pseudospin fully polarized. The spin-wave excitations are studied and\nfound to have quadratic dispersion relations at long wave length.",
        "positive": "Initial solidification dynamics of spreading droplets: When a droplet is brought in contact with an undercooled surface, it wets the\nsubstrate and solidifies at the same time. The interplay between the phase\ntransition effects and the contact-line motion, leading to its arrest, remains\npoorly understood. Here we reveal the early solidification patterns and\ndynamics of spreading hexadecane droplets. Total internal reflection (TIR)\nimaging is employed to temporally and spatially resolve the early\nsolidification behaviour. With this, we determine the conditions leading to the\ncontact-line arrest. We quantify the overall nucleation behaviour,\n\\textit{i.e.} the nucleation rate and the crystal growth speed, and show its\nsensitivity to the applied undercooling of the substrate. By combining the\nJohnson-Mehl-Avrami-Kolmogorov nucleation theory and scaling relations for the\nspreading, we can calculate the temporal evolution of the solid area fraction,\nwhich is in good agreement with our observations. We also show that for strong\nenough undercooling it is the rapid growth of the crystals which determines the\neventual arrest of the spreading contact line."
    },
    {
        "anchor": "Stable crystalline lattices in two-dimensional binary mixtures of\n  dipolar particles: The phase diagram of binary mixtures of particles interacting via a pair\npotential of parallel dipoles is computed at zero temperature as a function of\ncomposition and the ratio of their magnetic susceptibilities. Using lattice\nsums, a rich variety of different stable crystalline structures is identified\nincluding $A_mB_n$ structures. [$A$ $(B)$ particles correspond to large (small)\ndipolar moments.] Their elementary cells consist of triangular, square,\nrectangular or rhombic lattices of the $A$ particles with a basis comprising\nvarious structures of $A$ and $B$ particles. For small (dipolar) asymmetry\nthere are intermediate $AB_2$ and $A_2B$ crystals besides the pure $A$ and $B$\ntriangular crystals. These structures are detectable in experiments on granular\nand colloidal matter.",
        "positive": "Dispersion of run-and-tumble microswimmers through disordered media: Understanding the transport properties of microorganisms and self-propelled\nparticles in porous media has important implications for human health as well\nas microbial ecology. In free space, most microswimmers perform diffusive\nrandom walks as a result of the interplay of self-propulsion and orientation\ndecorrelation mechanisms such as run-and-tumble dynamics or rotational\ndiffusion. In an unstructured porous medium, collisions with the microstructure\nresult in a decrease in the effective spatial diffusivity of the particles from\nits free-space value. Here, we analyze this problem for a simple model system\nconsisting of non-interacting point particles performing run-and-tumble\ndynamics through a two-dimensional disordered medium composed of a random\ndistribution of circular obstacles, in the absence of Brownian diffusion or\nhydrodynamic interactions. The particles are assumed to collide with the\nobstacles as hard spheres and subsequently slide on the obstacle surface with\nno frictional resistance while maintaining their orientation, until they either\nescape or tumble. We show that the variations in the long-time diffusivity can\nbe described by a universal dimensionless hindrance function\n$f(\\phi,\\mathrm{Pe})$ of the obstacle area fraction $\\phi$ and P\\'eclet number\n$\\mathrm{Pe}$, or ratio of the swimmer run length to the obstacle size. We\nanalytically derive an asymptotic expression for the hindrance function valid\nfor dilute media ($\\mathrm{Pe}\\,\\phi\\ll 1$), and its extension to denser media\nis obtained using stochastic simulations."
    },
    {
        "anchor": "Euclidean random matrices, the glass transition and the Boson peak: In this paper I will describe some results that have been recently obtained\nin the study of random Euclidean matrices, i.e. matrices that are functions of\nrandom points in Euclidean space. In the case of translation invariant matrices\none generically finds a phase transition between a phonon phase and a saddle\nphase. If we apply these considerations to the study of the Hessian of the\nHamiltonian of the particles of a fluid, we find that this phonon-saddle\ntransition corresponds to the dynamical phase transition in glasses, that has\nbeen studied in the framework of the mode coupling approximation. The Boson\npeak observed in glasses at low temperature is a remanent of this transition.",
        "positive": "Variety of Scaling Laws for DNA Thermal Denaturation: We discuss possible mechanisms that may impact the order of the transition\nbetween denaturated and bound DNA states and lead to changes in the scaling\nlaws that govern conformational properties of DNA strands. To this end, we\nre-consider the Poland-Scheraga model and apply a polymer field theory approach\nto calculate entropic exponents associated with the denaturated loop\ndistribution. We discuss in particular variants of this transition that may\noccur due to the properties of the solution and may affect the self- and mutual\ninteraction of both single and double strands. We find that the effects studied\nsignificantly influence the strength of the first order transition. This is\nmanifest in particular by the changes in the scaling laws that govern DNA loop\nand strand distribution. As a quantitative measure of these changes we present\nthe values of corresponding scaling exponents. For the $d=4-\\varepsilon$ case\nwe get corresponding $\\varepsilon^4$ expansions and evaluate the perturbation\ntheory expansions at space dimension $d=3$ by means of resummation technique."
    },
    {
        "anchor": "Elastohydrodynamic Synchronization of Adjacent Beating Flagella: It is now well established that nearby beating pairs of eukaryotic flagella\nor cilia typically synchronize in phase. A substantial body of evidence\nsupports the hypothesis that hydrodynamic coupling between the active\nfilaments, combined with waveform compliance, provides a robust mechanism for\nsynchrony. This elastohydrodynamic mechanism has been incorporated into\n`bead-spring' models in which flagella are represented by microspheres tethered\nby radial springs as internal forces drive them about orbits. While these\nlow-dimensional models reproduce the phenomenon of synchrony, their parameters\nare not readily relatable to those of flagella. More realistic models which\nreflect the elasticity of the axonemes and active force generation take the\nform of fourth-order nonlinear PDEs. While computational studies have shown\nsynchrony, the effects of hydrodynamic coupling between nearby filaments\ngoverned by such models have been theoretically examined only in the regime of\ninterflagellar distances $d$ large compared to flagellar length $L$. Yet, in\nmany biological situations $d/L \\ll 1$. Here, we first present an asymptotic\nanalysis of the hydrodynamic coupling between two filaments in the regime $d/L\n\\ll 1$, and find that the form of the coupling is independent of the details of\nthe internal forces that govern the motion of the filaments. The analysis is\nlike the localized induction approximation for vortex filament motion, extended\nto the case of mutual induction. To understand how the coupling mechanism leads\nto synchrony of extended objects, we introduce a heuristic model of flagellar\nbeating, a single fourth-order nonlinear PDE whose form is derived from\nsymmetry considerations, the physics of elasticity, and the overdamped nature\nof the dynamics. Analytical and numerical studies of this model illustrate how\nsynchrony between two filaments is achieved through the asymptotic coupling.",
        "positive": "Structural transformations in porous glasses under mechanical loading.\n  I. Tension: The evolution of porous structure and mechanical properties of binary glasses\nunder tensile loading were examined using molecular dynamics simulations. We\nconsider vitreous systems obtained in the process of phase separation after a\nrapid isochoric quench of a glass-forming liquid to a temperature below the\nglass transition. The porous structure in undeformed samples varies from a\nconnected porous network to a random distribution of isolated pores upon\nincreasing average glass density. We find that at small strain, the elastic\nmodulus follows a power-law dependence on the average glass density and the\npore size distribution remains nearly the same as in quiescent samples. Upon\nfurther loading, the pores become significantly deformed and coalesce into\nlarger voids that leads to formation of system-spanning empty regions\nassociated with breaking of the material."
    },
    {
        "anchor": "A phase-space method for the Bose-Hubbard model: We present a phase-space method for the Bose-Hubbard model based on the\nQ-function representation. In particular, we consider two model Hamiltonians in\nthe mean-field approximation; the first is the standard \"one site\" model where\nquantum tunneling is approximated entirely using mean-field terms; the second\n\"two site\" model explicitly includes tunneling between two adjacent sites while\ntreating tunneling with other neighbouring sites using the mean-field\napproximation. The ground state is determined by minimizing the classical\nenergy functional subject to quantum mechanical constraints, which take the\nform of uncertainty relations. For each model Hamiltonian we compare the ground\nstate results from the Q-function method with the exact numerical solution. The\nresults from the Q-function method, which are easy to compute, give a good\nqualitative description of the main features of the Bose-Hubbard model\nincluding the superfluid to Mott insulator. We find the quantum mechanical\nconstraints dominate the problem and show there are some limitations of the\nmethod particularly in the weak lattice regime.",
        "positive": "Enhanced Thermal Transport through Soft Glassy Nano-disc Paste: We study diffusion of heat in an aqueous suspension of disc shaped\nnanoparticles of Laponite, which has finite elasticity and paste-like\nconsistency, by using the Mach-Zehnder interferometer. We estimate the thermal\ndiffusivity of the suspension by comparing the experimentally obtained\ntemperature distribution to that with analytical solution. We observe that\ndespite highly constrained Brownian diffusivity of particles owing to its soft\nglassy nature, suspensions at very small concentrations of Laponite\ndemonstrates significant enhancement in thermal diffusivity. We correlate the\nobserved enhancement with the possible microstructures of the Laponite\nsuspension."
    },
    {
        "anchor": "Thermal phototactic bioconvection in a suspension of isotropic\n  scattering phototactic microorganism: In this investigation, we explore the thermal effects on a suspension\ncontaining isotropic scattering phototactic microorganisms. The setup involves\nilluminating the suspension with collimated irradiation from the top, coupled\nwith heating or cooling applied from the bottom. The governing equations\nencompass the Navier-Stokes equations with the Boussinesq approximation, the\ndiffusion equation for motile microorganisms, and the energy equation for\ntemperature. Using linear perturbation theory, we conduct a comprehensive\nanalysis of the suspension's linear stability. The findings of this\ninvestigation reveal that the suspension experiences increased stability as a\nconsequence of scattering.",
        "positive": "Smectics $A$ and $C$, and the Transition between them, in Uniaxial\n  Disordered Environments: We present a theory of the elasticity and fluctuations of the Smectic A and C\nphases in uniaxial, anisotropic disordered environments, e.g., stretched\naerogel. We find that, bizarrely, the low-temperature, lower-symmetry Smectic\n$C$ phase is less translationally ordered than the high-temperature,\nhigher-symmetry Smectic $A$ phase, with short-ranged \"$m=1$ Bragg glass\" and\nalgebraic \"XY Bragg glass\" order, respectively. The $AC$ phase transition\nbelongs to a new universality class, whose fixed points and exponents we find\nin a $d=5-\\epsilon$ expansion. We give very detailed predictions for the very\nrich light scattering behavior of both phases, and the critical point."
    },
    {
        "anchor": "Dynamics of simple liquids at heterogeneous surfaces : Molecular\n  Dynamics simulations and hydrodynamic description: In this paper we consider the effect of surface heterogeneity on the slippage\nof fluid, using two complementary approaches. First, MD simulations of a\ncorrugated hydrophobic surface have been performed. A dewetting transition,\nleading to a super-hydrophobic state, is observed for pressure below a\n``capillary'' pressure. Conversely a very large slippage of the fluid on this\ncomposite interface is found in this superhydrophobic state. Second, we propose\na macroscopic estimate of the effective slip length on the basis of continuum\nhydrodynamics, in order to rationalize the previous MD results. This\ncalculation allows to estimate the effect of a heterogeneous slip length\npattern on the composite interface. Comparison between the two approaches are\nin good agreement at low pressure, but highlights the role of the exact shape\nof the liquid-vapor interface at higher pressure. These results confirm that\nsmall variations in the roughness of a surface can lead to huge differences in\nthe slip effect. On the basis of these results, we propose some guidelines to\ndesign highly slippery surfaces, motivated by potential applications in\nmicrofluidics.",
        "positive": "Electric Fields Near Undulating Dielectric Membranes: Dielectric interfaces are crucial to the behavior of charged membranes, from\ngraphene to synthetic and biological lipid bilayers. Understanding electrolyte\nbehavior near these interfaces remains a challenge, especially in the case of\nrough dielectric surfaces. A lack of analytical solutions consigns this problem\nto numerical treatments. We report an analytic method for determining\nelectrostatic potentials near curved dielectric membranes in a two-dimensional\nperiodic 'slab' geometry using a periodic summation of Green's functions. This\nmethod is amenable to simulating arbitrary groups of charges near surfaces with\ntwo-dimensional deformations. We concentrate on one-dimensional undulations. We\nshow that increasing membrane undulation increases the asymmetry of interfacial\ncharge distributions due to preferential ionic repulsion from troughs. In the\nlimit of thick membranes we recover results mimicking those for electrolytes\nnear a single interface. Our work demonstrates that rough surfaces generate\ncharge patterns in electrolytes of charged molecules or mixed-valence ions."
    },
    {
        "anchor": "Quantification of the volume-fraction reduction of sheared fragile\n  glass-forming liquids and its impact on rheology: This study determines the volume-fraction reduction of sheared fragile\nglass-forming liquids. We consider a group of hypothetical systems that consist\nof particles with anisotropic particle-size modulations yet have almost the\nsame average particle configuration as actual systems under shear flow. Our\nmolecular dynamics (MD) simulations demonstrate that one specific hypothetical\nsystem can reproduce the relaxation dynamics of an actual sheared system, and\nwe identify the shear-flow effect on the particle size with anisotropic\nsize-modulation of this specific system. Then, based on the determination of\nthe particle size and the resultant volume fraction, we rationalize how slight\ndecreases in the volume fraction significantly reduce the viscosity snf provide\na nonlinear constitutive equation. Notably, the obtained rheological\npredictions, including the crossover shear rate from Newtonian to non-Newtonian\nbehavior, can be expressed only in terms of experimental observables, showing a\ngood agreement with the MD simulation results. Our perspective on the volume\nfraction under shear flow may provide new insights into the conventional\nconcept of free-volume.",
        "positive": "Geometrical Frustration in Two Dimensions: Idealizations and\n  Realizations of a Hard Disc Fluid in Negative Curvature: We examine a simple hard disc fluid with no long range interactions on the\ntwo dimensional space of constant negative Gaussian curvature, the hyperbolic\nplane. This geometry provides a natural mechanism by which global crystalline\norder is frustrated, allowing us to construct a tractable model of disordered\nmonodisperse hard discs. We extend free area theory and the virial expansion to\nthis regime, deriving the equation of state for the system, and compare its\npredictions with simulation near an isostatic packing in the curved space.\nAdditionally, we investigate packing and dynamics on triply periodic,\nnegatively curved surfaces with an eye toward real biological and polymeric\nsystems."
    },
    {
        "anchor": "Linear and nonlinear rheology of dense emulsions: Identifying the glass\n  and jamming regimes: We discuss the linear and non-linear rheology of concentrated (sub)microscale\nemulsions, amorphous disordered solids composed of repulsive and deformable\nsoft colloidal spheres. Based on recent results from simulation and theory, we\nderive quantitative predictions for the dependences of the elastic shear\nmodulus and the yield stress on the droplet volume fraction. The remarkable\nagreement with experiments we observe supports the scenario that the repulsive\nglass and the jammed state can be clearly identified in the rheology of soft\nspheres at finite temperature while crossing continuously from a liquid to a\nhighly compressed yet disordered solid.",
        "positive": "Flying V and Reference Aircraft Evacuation Simulation and Comparison: A preliminary comparison of evacuation times of the Flying V and the Airbus\nA350-900 is presented in this study. A simple simulation tool based on the\ntechnique of cellular automata was created to model the evacuation process for\ndifferent closed door configurations. Certification regulations state that the\ntime to evacuate a civil aircraft in case of an emergency with half of all exit\ndoors closed must be less than 90 seconds. The results of this study indicate\nthat the shorter V shaped cabin has advantages over the longer conventional\nreference cabin for cases when passengers need to evacuate towards the front or\nthe back of the aircraft. Disadvantages occur when the passengers in the V\nshaped cabin need to evacuate more towards one side (left or right wing) of the\naircraft. A more detailed simulation model to further investigate these cases\nis currently created by the authors."
    },
    {
        "anchor": "Cyclic annealing as an iterated random map: Disordered magnets, martensitic mixed crystals, and glassy solids can be\nirreversibly deformed by subjecting them to external deformation. The\ndeformation produces a smooth, reversible response punctuated by abrupt\nrelaxation \"glitches\". Under appropriate repeated forward and reverse\ndeformation producing multiple glitches, a strict repetition of a single\nsequence of microscopic configurations often emerges. We exhibit these features\nby describing the evolution of the system configuration from glitch to glitch\nas a mapping of $\\mathcal{N}$ states into one-another. A map $\\mathbf{U}$\ncontrols forward deformation; a second map $\\mathbf{D}$ controls reverse\ndeformation. Iteration of a given sequence of forward and reverse maps, e.g.\n$\\mathbf{DDDDUUU}$ necessarily produces a convergence to a fixed cyclic\nrepetition of states covering multiple glitches. The repetition may have a\nperiod of more than one strain cycle, as recently observed in simulations.\nUsing numerical sampling, we characterize the convergence properties of four\ntypes of random maps implementing successive physical restrictions. The most\nrestrictive is the much-studied Preisach model. These maps show only the most\nqualitative resemblance to annealing simulations. However, they suggest further\nproperties needed for a realistic mapping scheme.",
        "positive": "Breakdown of the mirror image symmetry in the optical\n  absorption/emission spectra of oligo(para-phenylene)s: The absorption and emission spectra of most luminescent, pi-conjugated,\norganic molecules are the mirror image of each other. In some cases, however,\nthis symmetry is severely broken. In the present work, the asymmetry between\nthe absorption and fluorescence spectra in molecular systems consisting of\npara-linked phenyl rings is studied. The vibronic structure of the emission and\nabsorption bands is calculated from ab-initio quantum chemical methods and a\nsubsequent, rigorous Franck-Condon treatment. Good agreement with experiment is\nachieved. A clear relation can be established between the strongly anharmonic\ndouble-well potential for the phenylene ring librations around the long\nmolecular axis and the observed deviation from the mirror image symmetry.\nConsequences for related compounds and temperature dependent optical\nmeasurements are also discussed."
    },
    {
        "anchor": "Chaperone-assisted translocation of a polymer through a nanopore: Using Langevin dynamics simulations, we investigate the dynamics of\nchaperone-assisted translocation of a flexible polymer through a nanopore. We\nfind that increasing the binding energy $\\epsilon$ between the chaperone and\nthe chain and the chaperone concentration $N_c$ can greatly improve the\ntranslocation probability. Particularly, with increasing the chaperone\nconcentration a maximum translocation probability is observed for weak binding.\nFor a fixed chaperone concentration, the histogram of translocation time $\\tau$\nhas a transition from long-tailed distribution to Gaussian distribution with\nincreasing $\\epsilon$. $\\tau$ rapidly decreases and then almost saturates with\nincreasing binding energy for short chain, however, it has a minimum for longer\nchains at lower chaperone concentration. We also show that $\\tau$ has a minimum\nas a function of the chaperone concentration. For different $\\epsilon$, a\nnonuniversal dependence of $\\tau$ on the chain length $N$ is also observed.\nThese results can be interpreted by characteristic entropic effects for\nflexible polymers induced by either crowding effect from high chaperone\nconcentration or the intersegmental binding for the high binding energy.",
        "positive": "Charge and Synthesis Modification in PMMA-PDMS Copolymer Model Colloids: Colloidal charge in non-polar media is less well understood than its aqueous\ncounterpart and due to van der Waals forces its study is particularly\nchallenging in highly confined systems, for which on the other hand large\nlong-range electrostatic repulsions are heavily screened in aqueous media.\nEvidence from videomicroscopy is presented that a model system governed with\nsurfactant-mediated charging is governed by the steric stabilizer's specific\nchemistry."
    },
    {
        "anchor": "Serpentine channels: micro -- rheometers for fluid relaxation times: We propose a novel device capable of measuring the relaxation time of\nviscoelastic fluids as small as 1\\,ms. In contrast to most rheometers, which by\ntheir very nature are concerned with producing viscometric or\nnearly-viscometric flows, here we make use of an elastic instability which\noccurs in the flow of viscoelastic fluids with curved streamlines. To calibrate\nthe rheometer we combine simple scaling arguments with relaxation times\nobtained from first normal-stress difference data measured in a classical shear\nrheometer. As an additional check we also compare these relaxation times to\nthose obtained from Zimm theory and good agreement is observed. Once\ncalibrated, we show how the serpentine rheometer can be used to access smaller\npolymer concentrations and lower solvent viscosities where classical\nmeasurements become difficult or impossible to use due to inertial and/or\nresolution limitations. In the absence of calibration the serpentine channel\ncan still be a very useful comparative or index device.",
        "positive": "On the molecular correlations that result in field-dependent\n  conductivities in electrolyte solutions: Employing recent advances in response theory and nonequilibrium ensemble\nreweighting, we study the dynamic and static correlations that give rise to an\nelectric field-dependent ionic conductivity in electrolyte solutions. We\nconsider solutions modeled with both implicit and explicit solvents, with\ndifferent dielectric properties, and at multiple concentrations. Implicit\nsolvent models at low concentrations and small dielectric constants exhibit\nstrongly field-dependent conductivities. We compared these results to the\nOnsager-Wilson theory of the Wien effect, which provides a qualitatively\nconsistent prediction at low concentrations and high static dielectric\nconstants, but is inconsistent away from these regimes. The origin of the\ndiscrepancy is found to be increased ion correlations under these conditions.\nExplicit solvent effects act to suppress nonlinear responses, yielding a weakly\nfield-dependent conductivity over the range of physically realizable field\nstrengths. By decomposing the relevant time correlation functions, we find that\nthe insensitivity of the conductivity to the field results from the persistent\nfrictional forces on the ions from the solvent. Our findings illustrate the\nutility of nonequilibrium response theory in rationalizing nonlinear transport\nbehavior."
    },
    {
        "anchor": "A Mechanistic Model of the Organization of Cell Shapes in Epithelial\n  Tissues: The organization of cells within tissues plays a vital role in various\nbiological processes, including development and morphogenesis. As a result,\nunderstanding how cells self-organize in tissues has been an active area of\nresearch. In our study, we explore a mechanistic model of cellular organization\nthat represents cells as force dipoles that interact with each other via the\ntissue, which we model as an elastic medium. By conducting numerical\nsimulations using this model, we are able to observe organizational features\nthat are consistent with those obtained from vertex model simulations. This\napproach provides valuable insights into the underlying mechanisms that govern\ncellular organization within tissues, which can help us better understand the\nprocesses involved in development and disease.",
        "positive": "Fast and rewritable colloidal assembly via field synchronized particle\n  swapping: We report a technique to realize reconfigurable colloidal crystals by using\nthe controlled motion of particle defects above an externally modulated\nmagnetic substrate. The transport of particles is induced by applying a uniform\nrotating magnetic field to a ferrite garnet film characterized by a periodic\nlattice of magnetic bubbles. For filling factor larger than one colloid per\nbubble domain, the particle current arises from propagating defects where\nparticles synchronously exchange their position when passing from one occupied\ndomain to the next. The amplitude of an applied alternating magnetic field can\nbe used to displace the excess particles via a swapping mechanism, or to\nmobilize the entire colloidal system at a predefined speed."
    },
    {
        "anchor": "Intermittency in Two-Dimensional Turbulence with Drag: We consider the enstrophy cascade in forced two-dimensional turbulence with a\nlinear drag force. In the presence of linear drag, the energy wavenumber\nspectrum drops with a power law faster than in the case without drag, and the\nvorticity field becomes intermittent, as shown by the anomalous scaling of the\nvorticity structure functions. Using a previous theory, we compare numerical\nsimulation results with predictions for the power law exponent of the energy\nwavenumber spectrum and the scaling exponents of the vorticity structure\nfunctions $\\zeta_{2q}$ obtained in terms of the distribution of finite time\nLyapunov exponents. We also study, both by numerical experiment and theoretical\nanalysis, the multifractal structure of the viscous enstrophy dissipation in\nterms of its R\\'{e}nyi dimension spectrum $D_q$ and singularity spectrum\n$f(\\alpha)$. We derive a relation between $D_q$ and $\\zeta_{2q}$, and discuss\nits relevance to a version of the refined similarity hypothesis. In addition,\nwe obtain and compare theoretically and numerically derived results for the\ndependence on separation $r$ of the probability distribution of\n$\\delta_{\\V{r}}\\omega$, the difference between the vorticity at two points\nseparated by a distance $r$. Our numerical simulations are done on a $4096\n\\times 4096$ grid.",
        "positive": "Identification of arches in 2D granular packings: We identify arches in a bed of granular disks generated by a molecular\ndynamic-type simulation. We use the history of the deposition of the particles\nto identify the supporting contacts of each particle. Then, arches are defined\nas sets of mutually stable disks. Different packings generated through tapping\nare analyzed. The possibility of identifying arches from the static structure\nof a deposited bed, without any information on the history of the deposition,\nis discussed."
    },
    {
        "anchor": "Accurate and Efficient Numerical Simulation of Dielectrically\n  Anisotropic Particles: A variety of electrostatic phenomena, including the structure of electric\ndouble layers and the aggregation of charged colloids and proteins, are\naffected by nonuniform electric permittivity. These effects are frequently\nignored in analytical and computational studies, and particularly difficult to\nhandle in situations where multiple dielectric contrasts are present, such as\nin colloids that are heterogeneous in permittivity. We present an extension to\nthe Iterative Dielectric Solver developed by Barros and Luijten [Phys. Rev.\nLett. 113, 017801 (2014)] that makes it possible to accurately compute the\npolarization of anisotropic particles with multiple dielectric contrasts. This\nefficient boundary-element method-based approach is applicable to geometries\nthat are not amenable to other solvers, opening the possibility of studying\ncollective phenomena of dielectrically anisotropic particles. We provide\ninsight into the underlying physical reasons for this efficiency.",
        "positive": "Capillary Filling of Anodized Alumina Nanopore Arrays: The filling behavior of a room temperature solvent,\nperfluoromethylcyclohexane, in approximately 20 nm nanoporous alumina membranes\nwas investigated in situ with small angle x-ray scattering. Adsorption in the\npores was controlled reversibly by varying the chemical potential between the\nsample and a liquid reservoir via a thermal offset, $\\Delta$T. The system\nexhibited a pronounced hysteretic capillary filling transition as liquid was\ncondensed into the nanopores. These results are compared with Kelvin-Cohan\ntheory, with a modified Derjaguin approximation, as well as with predictions by\nCole and Saam."
    },
    {
        "anchor": "Motion of a Polymer Globule with Vicsek-like Activity: From\n  Super-diffusive to Ballistic Behavior: Via molecular dynamics simulation with Langevin thermostat we study the\nstructure and dynamics of a flexible bead-spring active polymer model after a\nquench from good to poor solvent conditions. The self propulsion is introduced\nvia a Vicsek-like alignment activity rule which works on each individual\nmonomer in addition to the standard attractive and repulsive interactions among\nthe monomeric beads. We observe that the final conformations are in the\nglobular phase for the passive as well as for all the active cases. By\ncalculating the bond length distribution, radial distribution function, etc.,\nwe show that the kinetics and also the microscopic details of these\n\\textit{pseudo equilibrium} globular conformations are not the same in all the\ncases. Moreover, the center-of-mass of the polymer shows a more directed\ntrajectory during its motion and the behavior of the mean-squared-displacement\ngradually changes from a super-diffusive to ballistic under the influence of\nthe active force in contrast to the diffusive behavior in the passive case.",
        "positive": "A microscopic view of the yielding transition in concentrated emulsions: We use a custom shear cell coupled to an optical microscope to investigate at\nthe particle level the yielding transition in concentrated emulsions subjected\nto an oscillatory shear deformation. By performing experiments lasting\nthousands of cycles on samples at several volume fractions and for a variety of\napplied strain amplitudes, we obtain a comprehensive, microscopic picture of\nthe yielding transition. We find that irreversible particle motion sharply\nincreases beyond a volume-fraction dependent critical strain, which is found to\nbe in close agreement with the strain beyond which the stress-strain relation\nprobed in rheology experiments significantly departs from linearity. The\nshear-induced dynamics are very heterogenous: quiescent particles coexist with\ntwo distinct populations of mobile and `supermobile' particles. Dynamic\nactivity exhibits spatial and temporal correlations, with rearrangements events\norganized in bursts of motion affecting localized regions of the sample.\nAnalogies with other sheared soft materials and with recent work on the\ntransition to irreversibility in sheared complex fluids are briefly discussed."
    },
    {
        "anchor": "Viscoplasticity and large-scale chain relaxation in glassy-polymeric\n  strain hardening: A simple theory for glassy polymeric mechanical response which accounts for\nlarge scale chain relaxation is presented. It captures the crossover from\nperfect-plastic response to strong strain hardening as the degree of\npolymerization $N$ increases, without invoking entanglements. By relating\nhardening to interactions on the scale of monomers and chain segments, we\ncorrectly predict its magnitude. Strain activated relaxation arising from the\nneed to maintain constant chain contour length reduces the $N$ dependence of\nthe characteristic relaxation time by a factor $\\sim \\dot\\epsilon N$ during\nactive deformation at strain rate $\\dot\\epsilon$. This prediction is consistent\nwith results from recent experiments and simulations, and we suggest how it may\nbe further tested experimentally.",
        "positive": "Drag on particles in a nematic suspension by a moving nematic-isotropic\n  interface: We report the first clear demonstration of drag on colloidal particles by a\nmoving nematic-isotropic interface. The balance of forces explains our\nobservation of periodic, strip-like structures that are produced by the\nmovement of these particles."
    },
    {
        "anchor": "Mechanics and force transmission in soft composites of rods in elastic\n  gels: We report detailed theoretical investigations of the micro-mechanics and bulk\nelastic properties of composites consisting of randomly distributed stiff\nfibers embedded in an elastic matrix in two and three dimensions. Recent\nexperiments published in Physical Review Letters [102, 188303 (2009)] have\nsuggested that the inclusion of stiff microtubules in a softer, nearly\nincompressible biopolymer matrix can lead to emergent compressibility. This can\nbe understood in terms of the enhancement of the compressibility of the\ncomposite relative to its shear compliance as a result of the addition of stiff\nrod-like inclusions. We show that the Poisson's ratio $\\nu$ of such a composite\nevolves with increasing rod density towards a particular value, or {\\em fixed\npoint}, independent of the material properties of the matrix, so long as it has\na finite initial compressibility. This fixed point is $\\nu=1/4$ in three\ndimensions and $\\nu=1/3$ in two dimensions. Our results suggest an important\nrole for stiff filaments such as microtubules and stress fibers in cell\nmechanics. At the same time, our work has a wider elasticity context, with\npotential applications to composite elastic media with a wide separation of\nscales in stiffness of its constituents such as carbon nanotube-polymer\ncomposites, which have been shown to have highly tunable mechanics.",
        "positive": "Three-boson recombination at ultralow temperatures: The effects of trimer continuum resonances are considered in the three-body\nrecombination rate of a Bose system at finite energies for large and negative\ntwo-body scattering lengths ($a$). The thermal average of the rate allows to\napply our formula to Bose gases at ultra-low temperatures. We found a good\nquantitative description of the experimental three-body recombination length of\ncesium atoms to deeply bound molecules up to 500 nK. Consistent with the\nexperimental data, the increase of the temperature moves the resonance peak of\nthe three-body recombination rate to lower values of $|a|$ exhibiting a\nsaturation behavior."
    },
    {
        "anchor": "Polymeric Assembly of Gluten Proteins in an Aqueous Ethanol Solvent: The supramolecular organization of wheat gluten proteins is largely unknown\ndue to the intrinsic complexity of this family of proteins and their\ninsolubility in water. We fractionate gluten in a water/ethanol (50/50 v/v) and\nobtain a protein extract which is depleted in gliadin, the monomeric part of\nwheat gluten proteins, and enriched in glutenin, the polymeric part of wheat\ngluten proteins. We investigate the structure of the proteins in the solvent\nused for extraction over a wide range of concentration, by combining X-ray\nscattering and multi-angle static and dynamic light scattering. Our data show\nthat, in the ethanol/water mixture, the proteins display features\ncharacteristic of flexible polymer chains in a good solvent. In the dilute\nregime, the protein form very loose structures of characteristic size 150 nm,\nwith an internal dynamics which is quantitatively similar to that of branched\npolymer coils. In more concentrated regimes, data highlight a hierarchical\nstructure with one characteristic length scale of the order of a few nm, which\ndisplays the scaling with concentration expected for a semi-dilute polymer in\ngood solvent, and a fractal arrangement at much larger length scale. This\nstructure is strikingly similar to that of polymeric gels, thus providing some\nfactual knowledge to rationalize the viscoelastic properties of wheat gluten\nproteins and their assemblies.",
        "positive": "Residual stresses couple microscopic and macroscopic scales: We show how residual stresses emerge in a visco-elastic material as a\nsignature of its past flow history, through an interplay between flow-modified\nmicroscopic relaxation and macroscopic features of the flow. Long-lasting\ntemporal-history dependence of the microscopic dynamics and nonlinear rheology\nare incorporated through the mode-coupling theory of the glass transition\n(MCT). The theory's integral constitutive equation (ICE) is coupled to\ncontinuum mechanics in a finite-element method (FEM) scheme that tracks the\nflow history through the Finger tensor. The method is suitable for a\ncalculation of residual stresses from a \"first-principles\" starting point\nfollowing well-understood approximations. As an example, we calculate within a\nschematic version of MCT the stress-induced optical birefringence pattern of an\namorphous solid cast into the shape of a slab with a cylindrical obstacle and\ndemonstrate how FEM-MCT can predict the dependence of material properties on\nthe material's processing history."
    },
    {
        "anchor": "Wound opening in a thin incompressible viscoelastic tissue: We develop a model to investigate analytically and numerically the mechanics\nof wound opening made in a viscoelastic, isotropic, homogeneous, and\nincompressive thin tissue. This process occurs just immediately after the wound\ninfliction. Before any active biological action has taken place, the tissue\nrelaxes, and the wound opens mostly due to the initial homeostatic tension of\nthe tissue, its elastic and viscous properties, and the existing friction\nbetween the tissue and its substrate. We find that for a circular wound the\nregimes of deformation are defined by a single adimensional parameter\n$\\lambda$, which characterizes the relative importance of viscosity over\nfriction.",
        "positive": "Calculation of mode coupling for quadrupole excitations in a\n  Bose-Einstein condensate: In this paper we give a theoretical description of resonant coupling between\ntwo collective excitations of a Bose condensed gas (BEC) on, or close, to a\nsecond harmonic resonance. Using analytic expressions for the quasi-particle\nwavefunctions we show that the coupling between quadrupole modes is strong,\nleading to a coupling time of a few milliseconds (for a TOP trap with radial\nfrequency 100 Hz and 10^4 atoms). Using the hydrodynamic approximation, we\nderive analytic expression for the coupling matrix element. These can be used\nwith an effective Hamiltonian (that we also derive) to describe the dynamics of\nthe coupling process and the associated squeezing effects."
    },
    {
        "anchor": "Depinning and plasticity of driven disordered lattices: We review in these notes the dynamics of extended condensed matter systesm,\nsuch as vortex lattices in type-II superconductors and charge density waves in\nanisotropic metals, driven over quenched disorder. We focus in particular on\nthe case of strong disorder, where topological defects are generated in the\ndriven lattice. In this case the repsonse is plastic and the depinning\ntransition may become discontinuous and hysteretic.",
        "positive": "Dynamic Surface Tension of Aqueous Solutions of Ionic Surfactants: Role\n  of Electrostatics: The adsorption kinetics of the cationic surfactant dodecyltrimethylammonium\nbromide at the air-water interface has been studied by the maximum bubble\npressure method at concentrations below the critical micellar concentration. At\nshort times, the adsorption is diffusion-limited. At longer times, the surface\ntension shows an intermediate plateau and can no longer be accounted for by a\ndiffusion limited process. Instead, adsorption appears kinetically controlled\nand slowed down by an adsorption barrier. A Poisson-Boltzmann theory for the\nelectrostatic repulsion from the surface does not fully account for the\nobserved potential barrier. The possibility of a surface phase transition is\nexpected from the fitted isotherms but has not been observed by Brewster angle\nmicroscopy."
    },
    {
        "anchor": "Effective potentials induced by self-assembly of patchy particles: Effective colloid-colloid interactions can be tailored through the addition\nof a complex cosolute. Here we investigate the case of a cosolute made by\nself-assembling patchy particles. Depending on the valence, these particles can\nform either polymer chains or branched structures. We numerically calculate the\neffective potential $V_{eff}$ between two colloids immersed in a suspension of\nreversible patchy particles, exploring a wide region of the cosolute phase\ndiagram and the role of valence. In addition to well-known excluded volume and\ndepletion effects, we find that, under appropriate conditions, $V_{eff}$ is\ncompletely attractive but shows an oscillatory character. In the case of\npolymerizing cosolute, this results from the fact that chains are efficiently\nconfined by the colloids through the onset of local order. This argument is\nthen generalized to the case of particles with higher valence, under the\ncondition that they are still able to maintain a fully bonded organization upon\nconfinement. The resulting effective potentials are relevant for understanding\nthe behavior of complex mixtures in crowded environments, but may also be\nexploited for tuning colloidal self-assembly at preferred target distances in\norder to build desired superstructures.",
        "positive": "Mechanical properties and microdomain separation of fluid membranes with\n  anchored polymers: The entropic effects of anchored polymers on biomembranes are studied using\nsimulations of a meshless membrane model combined with anchored linear polymer\nchains. The bending rigidity and spontaneous curvature are investigated for\nanchored ideal and excluded-volume polymer chains. Our results are in good\nagreement with the previous theoretical predictions. It is found that the\npolymer reduces the line tension of membrane edges, as well as the interfacial\nline tension between membrane domains, leading to microdomain formation.\nInstead of the mixing of two phases as observed in typical binary fluids,\ndensely anchored polymers stabilize small domains. A mean field theory is\nproposed for the edge line tension reduced by anchored ideal chains, which\nreproduces our simulation results well."
    },
    {
        "anchor": "Surface phase transitions in polydisperse hard rod fluids: I study the effect of length polydispersity in the surface phase diagram of\nhard rods interacting with a hard wall. The properly extended interface\nGibbs-Duhem equation for a polydisperse system allows us to predict the\nbehaviour of the surface tension as a function of the bulk density at the the\nwall-isotropic interface. Two groups of qualitative different bulk and surface\nphase diagrams are calculated from two families of parametrized length\ndistribution functions $p(l)$. This parameterization controls the law of decay\nat large $l$. I also study the segregation due to polydispersity at the\nisotropic-nematic interface and the capillary nematization phenomena as a\nfunction of polydispersity.",
        "positive": "Shear modulus and Dilatancy Softening in Granular Packings above Jamming: We investigate experimentally the mechanical response of a monolayer of\nbi-disperse frictional grains to an inhomogeneous shear perturbation across the\njamming transition. We inflate an intruder inside the packing and use\nphoto-elasticity and tracking techniques to measure the induced shear strain\nand stresses at the grain scale. We quantify experimentally the constitutive\nrelations for strain amplitudes as low as 0.001 and for a range of packing\nfractions within 2% variation around the jamming transition. At the transition\nstrong nonlinear effects set in : both the shear modulus and the dilatancy\nshear-soften at small strain until a critical strain is reached where effective\nlinearity is recovered. The dependencies of the critical strain and the\nassociated critical stresses on the distance from jamming are extracted via\nscaling analysis. We check that the constitutive laws, when applied to the\nequations governing mechanical equilibrium, lead to the observed stress and\nstrain profiles. These profiles exhibit a spatial crossover between an\neffective linear regime close to the inflater and the truly nonlinear regime\naway from it. The crossover length diverges at the jamming transition."
    },
    {
        "anchor": "Velocity Distributions of Granular Gases with Drag and with Long-Range\n  Interactions: We study velocity statistics of electrostatically driven granular gases. For\ntwo different experiments: (i) non-magnetic particles in a viscous fluid and\n(ii) magnetic particles in air, the velocity distribution is non-Maxwellian,\nand its high-energy tail is exponential, P(v) ~ exp(-|v|). This behavior is\nconsistent with kinetic theory of driven dissipative particles. For particles\nimmersed in a fluid, viscous damping is responsible for the exponential tail,\nwhile for magnetic particles, long-range interactions cause the exponential\ntail. We conclude that velocity statistics of dissipative gases are sensitive\nto the fluid environment and to the form of the particle interaction.",
        "positive": "Dynamics of equilibrium linked colloidal gels: Colloids that attractively bond to only a few neighbors (e.g., patchy\nparticles) can form equilibrium gels with distinctive dynamic properties that\nare stable in time. Here, we use a coarse-grained model to explore the dynamics\nof linked networks of patchy colloids whose average valence is macroscopically,\nrather than microscopically, constrained. Simulation results for the model show\ndynamic hallmarks of equilibrium gel formation and establish that the\ncolloid-colloid bond persistence time controls the characteristic slow\nrelaxation of the self-intermediate scattering function. The model features\nre-entrant network formation without phase separation as a function of linker\nconcentration, centered at the stoichiometric ratio of linker ends to\nnanoparticle surface bonding sites. Departures from stoichiometry result in\nlinker-starved or site-starved networks with reduced connectivity and shorter\ncharacteristic relaxation times with lower activation energies. Underlying the\nre-entrant trends, dynamic properties vary monotonically with the number of\neffective network bonds per colloid, a quantity that can be predicted using\nWertheim's thermodynamic perturbation theory. These behaviors suggest\nmacroscopic in situ strategies for tuning the dynamical response of colloidal\nnetworks."
    },
    {
        "anchor": "Drainage of a nanoconfined simple fluid: rate effects on squeeze-out\n  dynamics: We investigate the effect of loading rate on drainage in molecularly thin\nfilms of a simple fluid made of quasi-spherical molecules\n(octamethylcyclotetrasiloxane, OMCTS). We find that (i) rapidly confined OMCTS\nretains its tendency to organize into layers parallel to the confining\nsurfaces, and (ii) flow resistance in such layered films can be described by\nbulklike viscous forces if one accounts for the existence of one monolayer\nimmobilized on each surfaces. The latter result is fully consistent with the\nrecent work of Becker and Mugele, who reached a similar conclusion by analyzing\nthe dynamics of squeeze-out fronts in OMCTS [T. Becker and F. Mugele, Phys.\nRev. Lett. {\\bf 91} 166104(2003)]. Furthermore, we show that the confinement\nrate controls the nature of the thinning transitions: layer-by-layer expulsion\nof molecules in metastable, slowly confined films proceeds by a\nnucleation/growth mechanism, whereas deeply and rapidly quenched films are\nunstable and undergo thinning transitions akin to spinodal decomposition.",
        "positive": "A Symmetric Free Energy Based Multi-Component Lattice Boltzmann Method: We present a lattice Boltzmann algorithm based on an underlying free energy\nthat allows the simulation of the dynamics of a multicomponent system with an\narbitrary number of components. The thermodynamic properties, such as the\nchemical potential of each component and the pressure of the overall system,\nare incorporated in the model. We derived a symmetrical convection diffusion\nequation for each component as well as the Navier Stokes equation and\ncontinuity equation for the overall system. The algorithm was verified through\nsimulations of binary and ternary systems. The equilibrium concentrations of\ncomponents of binary and ternary systems simulated with our algorithm agree\nwell with theoretical expectations."
    },
    {
        "anchor": "A stochastic flow rule for granular materials: There have been many attempts to derive continuum models for dense granular\nflow, but a general theory is still lacking. Here, we start with Mohr-Coulomb\nplasticity for quasi-2D granular materials to calculate (average) stresses and\nslip planes, but we propose a \"stochastic flow rule\" (SFR) to replace the\nprinciple of coaxiality in classical plasticity. The SFR takes into account two\ncrucial features of granular materials - discreteness and randomness - via\ndiffusing \"spots\" of local fluidization, which act as carriers of plasticity.\nWe postulate that spots perform random walks biased along slip-lines with a\ndrift direction determined by the stress imbalance upon a local switch from\nstatic to dynamic friction. In the continuum limit (based on a Fokker-Planck\nequation for the spot concentration), this simple model is able to predict a\nvariety of granular flow profiles in flat-bottom silos, annular Couette cells,\nflowing heaps, and plate-dragging experiments -- with essentially no fitting\nparameters -- although it is only expected to function where material is at\nincipient failure and slip-lines are inadmissible. For special cases of\nadmissible slip-lines, such as plate dragging under a heavy load or flow down\nan inclined plane, we postulate a transition to rate-dependent Bagnold\nrheology, where flow occurs by sliding shear planes. With different yield\ncriteria, the SFR provides a general framework for multiscale modeling of\nplasticity in amorphous materials, cycling between continuum limit-state stress\ncalculations, meso-scale spot random walks, and microscopic particle\nrelaxation.",
        "positive": "How large should be the redundant numbers of copy to make a rare event\n  probable: The redundancy principle provides the framework to study how rare events are\nmade possible with probability 1 in accelerated time, by making many copies of\nsimilar random searchers. But what is $n$ large? To estimate large $n$ with\nrespect to the geometrical properties of a domain and the dynamics, we present\nhere a criteria based on splitting probabilities between a small fraction of\nthe exploration space associated to an activation process and other absorbing\nregions where trajectories can be terminated. We obtain explicit computations\nespecially when there is a killing region located inside the domain that we\ncompare with stochastic simulations. We present also examples of extreme\ntrajectories with killing in dimension 2. For a large $n$, the optimal\ntrajectories avoid penetrating inside the killing region. Finally we discuss\nsome applications to cell biology."
    },
    {
        "anchor": "Evidence for the role of fluctuations in the thermodynamics of nanoscale\n  drops and the implications in computations of the surface tension: Test area deformations are used to analyse vapour-liquid interfaces of\nLennard-Jones particles by molecular dynamics simulation. For planar\nvapour-liquid interfaces the change in free energy is captured by the average\nof the corresponding change in energy, the leading-order contribution. This is\nconsistent with the commonly used mechanical (pressure tensor) route for the\nsurface tension. By contrast for liquid drops one finds a large second-order\ncontribution associated with fluctuations in energy. Both the first- and\nsecond-order terms make comparable contributions, invalidating the mechanical\nrelation for the surface tension of small drops. The latter is seen to increase\nabove the planar value for drop radii of ~8 particle diameters, followed by an\napparent weak maximum and slow decay to the planar limit, consistent with a\nsmall negative Tolman length.",
        "positive": "Two-dimensional, blue phase tactoids: We use full nematohydrodynamic simulations to study the statics and dynamics\nof monolayers of cholesteric liquid crystals. Using chirality and temperature\nas control parameters we show that we can recover the two-dimensional blue\nphases recently observed in chiral nematics, where hexagonal lattices of\nhalf-skyrmion topological excitations are interleaved by lattices of trefoil\ntopological defects. Furthermore, we characterise the transient dynamics during\nthe quench from isotropic to blue phase. We then proceed by confining\ncholesteric stripes and blue phases within finite-sized tactoids and show that\nit is possible to access a wealth of reconfigurable droplet shapes including\ndisk-like, elongated, and star-shaped morphologies. Our results demonstrate a\npotential for constructing controllable, stable structures of liquid crystals\nby constraining 2D blue phases and varying the chirality, surface tension and\nelastic constants."
    },
    {
        "anchor": "Stamping and wrinkling of elastic plates: We study the peculiar wrinkling pattern of an elastic plate stamped into a\nspherical mold. We show that the wavelength of the wrinkles decreases with\ntheir amplitude, but reaches a maximum when the amplitude is of the order of\nthe thickness of the plate. The force required for compressing the wrinkled\nplate presents a maximum independent of the thickness. A model is derived and\nverified experimentally for a simple one-dimensional case. This model is\nextended to the initial situation through an effective Young modulus\nrepresenting the mechanical behavior of wrinkled state. The theoretical\npredictions are shown to be in good agreement with the experiments. This\napproach provides a complement to the \"tension field theory\" developed for\nwrinkles with unconstrained amplitude.",
        "positive": "Closed formula for the transport of micro-nano-particle across model\n  porous media: In the last decade the Fick-Jacobs approximation has been exploited to\ncapture the transport across constrictions. Here, we review the derivation of\nthe Fick-Jacobs equation with particular emphasis on its linear response\nregime. We show that for fore-aft symmetric channels the flux of\nnon-interacting systems is fully captured by its linear response regime. For\nthis case we derive a very simple formula that captures the correct trends and\nthat can be exploited as a simple tool to design experiments or simulations.\nFinally, we show that higher order corrections in the flux may appear for\nnon-symmetric channels."
    },
    {
        "anchor": "Beyond Poisson-Boltzmann: Numerical sampling of charge density\n  fluctuations: We present a method aimed at sampling charge density fluctuations in Coulomb\nsystems. The derivation follows from a functional integral representation of\nthe partition function in terms of charge density fluctuations. Starting from\nthe mean-field solution given by the Poisson-Boltzmann equation, an original\napproach is proposed to numerically sample fluctuations around it, through the\npropagation of a Langevin like stochastic partial differential equation (SPDE).\nThe diffusion tensor of the SPDE can be chosen so as to avoid the numerical\ncomplexity linked to long-range Coulomb interactions, effectively rendering the\ntheory completely local. A finite-volume implementation of the SPDE is\ndescribed, and the approach is illustrated with preliminary results on the\nstudy of a system made of two like-charge ions immersed in a bath of\ncounter-ions.",
        "positive": "Influence of an adsorbing polymer in the aging dynamics of Laponite clay\n  suspensions: Clay-polymer dispersions in aqueous solutions have attracted a great interest\nin recent years due to their industrial applications and intriguing physical\nproperties. Aqueous solutions of bare Laponite particles are known to age\nspontaneously from an ergodic state to a non ergodic state in a time varying\nfrom hours to months depending on Laponite concentration. When a polymer\nspecies like Polyethylene Oxide (PEO) is added to the solution, it weakly\nadsorbs on clay particle surfaces modifying the effective interaction potential\nbetween Laponite particles. A dynamic light scattering study, varying polymer\nconcentration at fixed polymer molecular weight (Mw=200.000 g/mol), has been\nperformed in order to understand the effect of polymer on the aging dynamics of\nthe system. The results obtained show that arresting phenomena between clay\nparticles are hindered if PEO is added and consequently the aging dynamics\nslows down with increasing PEO concentration. This process is possibly due to\nthe progressive coverage of the clay surface by polymers that grow with\nincreasing PEO concentration and may lead to steric stabilization."
    },
    {
        "anchor": "Electrostatically tunable axisymmetric vibrations of soft electro-active\n  tubes: Due to their unique electromechanical coupling properties, soft\nelectro-active (SEA) resonators are actively tunable, extremely suitable, and\npractically important for designing the next-generation acoustic and vibration\ntreatment devices. In this paper, we investigate the electrostatically tunable\naxisymmetric vibrations of SEA tubes with different geometric sizes. We\nconsider both axisymmetric torsional and longitudinal vibrations for an\nincompressible SEA cylindrical tube under inhomogeneous biasing fields induced\nby radial electric voltage and axial pre-stretch. We then employ the\nstate-space method, which combines the state-space formalism in cylindrical\ncoordinates with the approximate laminate technique, to derive the frequency\nequations for two separate classes of axisymmetric vibration of the tube\nsubjected to appropriate boundary conditions. We perform numerical calculations\nto validate the convergence and accuracy of the state-space method and to\nilluminate that the axisymmetric vibration characteristics of SEA tubes may be\ntuned significantly by adjusting the electromechanical biasing fields as well\nas altering the tube geometry. The reported results provide a solid guidance\nfor the proper design of tunable resonant devices composed of SEA tubes",
        "positive": "Anomalous near-equilibrium capillary rise: We report and rationalize the observation of a crossover from the classical\nLucas-Washburn dynamics to a long-lived anomalously slow regime for capillary\nrise in simple glass tubes. We propose an analytical model considering the role\nof thermal motion and the nanoscale surface topography to account for the\nexperimental observations. The proposed model indicates that the contact line\nperimeter and the surface topography dimensions determine the crossover\ncondition and anomalous imbibition rate. Our findings have important\nimplications for the scientific understanding and technical application of\ncapillary imbibition and suggest strategies to control the adsorption of\nspecific liquids in porous materials."
    },
    {
        "anchor": "Raft Instability of Biopolymer Gels: Following recent X-ray diffraction experiments by Wong, Li, and Safinya on\nbiopolymer gels, we apply Onsager excluded volume theory to a nematic mixture\nof rigid rods and strong ``$\\pi/2$'' cross-linkers obtaining a long-ranged,\nhighly anisotropic depletion attraction between the linkers. This attraction\nleads to breakdown of the percolation theory for this class of gels, to\nbreakdown of Onsager's second-order virial method, and to formation of\nheterogeneities in the form of raft-like ribbons.",
        "positive": "pH-dependent water permeability switching and its memory in 1T' MoS$_2$\n  membranes: Intelligent transport of molecular species across different barriers is\ncritical for various biological functions and is achieved through the unique\nproperties of biological membranes. An essential feature of intelligent\ntransport is the ability to adapt to different external and internal conditions\nand also the ability to memorise the previous state. In biological systems, the\nmost common form of such intelligence is expressed as hysteresis. Despite\nnumerous advances made over previous decades on smart membranes, it is still a\nchallenge for a synthetic membrane to display stable hysteretic behaviour for\nmolecular transport. Here we show the memory effects and stimuli regulated\ntransport of molecules through an intelligent phase changing MoS$_2$ membrane\nin response to external pH. We show that water and ion permeation through 1T'\nMoS$_2$ membranes follows a pH dependent hysteresis with a permeation rate that\nswitches by a few orders of magnitude. We demonstrate that this phenomenon is\nunique to the 1T' phase of MoS$_2$ due to the presence of surface charge and\nexchangeable ions on the surface. We further demonstrate the potential\napplication of this phenomenon in autonomous wound infection monitoring and\npH-dependent nanofiltration. Our work significantly deepens understanding of\nthe mechanism of water transport at the nanoscale and opens an avenue for\ndeveloping neuromorphic applications, smart drug delivery systems,\npoint-of-care diagnostics, smart sensors, and intelligent filtration devices."
    },
    {
        "anchor": "Wetting equilibrium in a rectangular channel: When a capillary channel with corners is wetted by a fluid, there are regions\nwhere the fluid fills the whole cross-section and regions where only the\ncorners are filled by the fluid. The fluid fraction of the partially-filled\nregion, $s^*$, is an important quantity related to the capillary pressure. We\ncalculate the value of $s^*$ for channels with a cross-section slightly\ndeviated from a rectangle: the height is larger in the center than those on the\ntwo short sides. We find that a small change in the cross-section geometry\nleads to a huge change of $s^*$. This result is consistent with experimental\nobservations.",
        "positive": "Two-color differential dynamic microscopy for capturing fast dynamics: Differential dynamic microscopy (DDM) is increasingly used in the fields of\nsoft matter physics and biophysics to extract the dynamics of microscopic\nobjects across a range of wavevectors using optical microscopy. Standard DDM is\nlimited to detecting dynamics no faster than the camera frame rate. We report\non an extension to DDM where we sequentially illuminate the sample with\nspectrally-distinct light and image with a color camera. By pulsing blue and\nthen red light separated by a lag time much smaller than the camera's exposure\ntime we are able to use this two-color DDM method to measure dynamics occurring\nmuch faster than the camera frame rate."
    },
    {
        "anchor": "Information weights of nucleotides in DNA sequences: The coding sequence in DNA molecule is considered as a message to be\ntransferred to receiver, the proteins, through a noisy information channel and\neach nucleotide is assigned a respective information weight. With the help of\nthe nucleotide substitution matrix we estimated the lower bound of the amount\nof information carried out by nucleotides which is not subject of mutations. We\nused the calculated weights to reconstruct k-oligomers of genes from the\nBorrelia burgdorferi genome. We showed, that to this aim there is sufficient a\nsimple rule, that the number of bits of the carried information cannot exceed\nsome threshold value. The method introduced by us is general and applies to\nevery genome.",
        "positive": "Fluidization of a vertically oscillated shallow granular layer: Molecular dynamics simulations are used to study fluidization of a vertically\nvibrated, three-dimensional shallow granular layer. As the container\nacceleration is increased above g, the granular temperature and root mean\nsquare particle displacement increase, gradually fluidizing the layer. For\nnearly elastic particles, or low shaking frequencies, or small layer depths,\nthe end of the fluidization process is marked by an abrupt increase in the\ngranular temperature and rms particle displacement. The layer is then fully\nfluidized since macroscopic, fluid-like phenomena such as convection rolls and\nsurface waves are observed. Increasing the total dissipation (by either\ndecreasing the restitution coefficient or increasing the total number of\nparticles) decreases the increase in granular temperature and rms particle\ndisplacement at fluidization, and shifts the increase to higher accelerations.\nIncreasing the frequency also decreases the magnitude of the jump, and shifts\nthe change to lower accelerations."
    },
    {
        "anchor": "Unexpected bending behavior of 2D lattice materials: Architected 2D lattice materials are appealing for shape-shifting\napplications due to the tunable sign of Poisson's ratio. It is commonly\nbelieved that the positive and negative Poisson's ratios lead to anticlastic\nand synclastic curvatures respectively when the material is bent in one\ndirection. Here, taking 2D beam lattices with star-shaped unit cells as\nexamples, we show theoretically and demonstrate experimentally that this is not\nalways true. At a fixed Poisson's ratio, we find a transition between\nanticlastic and synclastic bending curvatures controlled by the beam's\ncross-sectional aspect ratio. Such an unexpected behavior roots in the\ncompetition between torsion and bending of the beams, and can be well captured\nby a Cosserat continuum model.",
        "positive": "Ordering of the lamellar phase under a shear flow: The dynamics of a system quenched into a state with lamellar order and\nsubject to an uniform shear flow is solved in the large-N limit. The\ndescription is based on the Brazovskii free-energy and the evolution follows a\nconvection-diffusion equation. Lamellae order preferentially with the normal\nalong the vorticity direction. Typical lengths grow as $\\gamma t^{5/4}$ (with\nlogarithmic corrections) in the flow direction and logarithmically in the shear\ndirection. Dynamical scaling holds in the two-dimensional case while it is\nviolated in D=3."
    },
    {
        "anchor": "Effect of Volume and Temperature on the Global and Segmental Dynamics in\n  Polypropylene Glycol and 1,4-polyisoprene: Published dielectric relaxation measurements on polypropylene glycol and\n1,4-polyisoprene are analyzed to determine the relative effect that thermal\nenergy and volume have on the temperature dependence of the normal mode\nrelaxation times, and compare this to their effect on the temperature\ndependence of the local segmental relaxation times. We find that for both\npolymers at temperatures well above Tg, both relaxation modes are governed more\nby thermal energy than by volume, although the latter's contribution is not\nnegligible. Such a result is consistent with an assumption underlying models\nfor polymer viscoelasticity, such as the Rouse and tube models, that the\nfriction coefficient governing motions over large length scales can be\nidentified with the local segmental friction coefficient. We also show that\nrelaxation data for both the segmental and the normal mode superimpose, when\nexpressed as a function of the product of the temperature and the volume, the\nlatter raised to a power. This scaling form arises from an inverse power form\nfor the intermolecular potential. The value of the exponent on the volume for\nthese two polymers indicates a relatively \"soft\" potential.",
        "positive": "RNA folding landscapes from explicit solvent all-atom simulations: Atomically detailed simulations of RNA folding have proven very challenging\nin view of the difficulties of developing realistic force fields and the\nintrinsic computational complexity of sampling rare conformational transitions.\nTo tackle both these issues, we extend to RNA an enhanced path sampling method\npreviously successfully applied to proteins. In this scheme, the information\nabout the RNA's native structure is harnessed by a soft history-dependent\nbiasing force, which is added to the atomistic force field, thus promoting the\ngeneration of productive folding trajectories. Here, we report on the results\nof simulations in explicit solvent of RNA molecules from 20 to 47 nucleotides\nlong and increasing topological complexity. From a statistical analysis of the\nfolding pathways we infer that, differently from proteins, the underlying free\nenergy landscape is significantly frustrated, even for relatively small chains\nwith a simple topology. The folding mechanism and the thermodynamics are in\nagreement with the available experiments and some of the existing\ncoarse-grained models. This scheme provides a fully microscopic\ncharacterization of RNA folding, relating the kinetics and dynamics of the\ntransition to the chemistry of the chain and its solvent. Therefore, it\nprovides a transferable framework that sets the stage for future translational\napplications."
    },
    {
        "anchor": "Functionality and Protein-Water Interactions: The structures of proteins exhibit secondary elements composed of helices and\nloops. Comparison of several water-only hydrophobicity scales with the\nfunctionalities of two repeat proteins shows that these secondary elements\npossess water-induced medium-range order that is sometimes similar, but can\nalso be complementary, to structural order. Study of these hitherto \"phantom\"\norder parameters promises far-reaching incremental improvements in the theory\nof protein dynamics. A by-product of the theory is an independent evaluation of\nthe reliability of different hydrophobicity scales.",
        "positive": "Sequences of dislocation reactions and helicity transformations in\n  tubular crystals: Freestanding tubular crystals offer a general description of crystalline\norder on deformable surfaces with cylindrical topology, such as single-walled\ncarbon nanotubes, microtubules, and recently reported colloidal assemblies.\nThese systems exhibit a rich interplay between the crystal's helicity on its\nperiodic surface, the deformable geometry of that surface, and the motions of\ntopological defects within the crystal. Previously, in simulations of tubular\ncrystals as elastic networks, we found that dislocations in nontrivial patterns\ncan co-stabilize with kinks in the tube shape, producing mechanical\nmultistability. Here, we extend that work with detailed Langevin dynamics\nsimulations, in order to explore defect dynamics efficiently and without the\nconstraints imposed by elastic network models. Along with the predicted\nmultistability of dislocation glide, we find a variety of irreversible defect\ntransformations, including vacancy formation, particle extrusions, and\n\"reactions\" that reorient dislocation pairs. Moreover, we report spontaneous\nsequences of several such defect transformations, which are unique to tubular\ncrystals. We demonstrate a simple method for controlling these sequences\nthrough a time-varying external force."
    },
    {
        "anchor": "Effect of architecture disorder on the elastic response of\n  two-dimensional lattice materials: We examine how disordering joint position influences the linear elastic\nbehavior of lattice materials via numerical simulations in two-dimensional beam\nnetworks. Three distinct initial crystalline geometries are selected as\nrepresentative of mechanically isotropic materials low connectivity,\nmechanically isotropic materials with high connectivity, and mechanically\nanisotropic materials with intermediate connectivity. Introducing disorder\ngenerates spatial fluctuations in the elasticity tensor at the local (joint)\nscale. Proper coarse-graining reveals a well-defined continuum-level scale\nelasticity tensor. Increasing disorder aids in making initially anisotropic\nmaterials more isotropic. The disorder impact on the material stiffness depends\non the lattice connectivity: Increasing the disorder softens lattices with high\nconnectivity and stiffens those with low connectivity, without modifying the\nscaling between elastic modulus and density (linear scaling for high\nconnectivity and cubic scaling for low connectivity). Introducing disorder in\nlattices with intermediate fixed connectivity reveals both scaling: the linear\nscaling occurs for low density, the cubic one at high density, and the\ncrossover density increases with disorder. Contrary to classical formulations,\nthis work demonstrates that connectivity is not the sole parameter governing\nelastic modulus scaling. It offers a promising route to access novel mechanical\nproperties in lattice materials via disordering the architectures.",
        "positive": "Segmental relaxation in semicrystalline polymers: a mean field model for\n  the distribution of relaxation times in confined regimes: The effect of confinement in the segmental relaxation of polymers is\nconsidered. On the basis of a thermodynamic model we discuss the emerging\nrelevance of the fast degrees of freedom in stimulating the much slower\nsegmental relaxation, as an effect of the constraints at the walls of the\namorphous regions. In the case that confinement is due to the presence of\ncrystalline domains, a quasi-poissonian distribution of local constraining\nconditions is derived as a result of thermodynamic equilibrium. This implies\nthat the average free energy barrier $\\Delta F$ for conformational\nrearrangement is of the same order of the dispersion of the barrier heights,\n$\\delta (\\Delta F)$, around $\\Delta F$. As an example, we apply the results to\nthe analysis of the $\\alpha$-relaxation as observed by dielectric broad band\nspectroscopy in semicrystalline poly(ethylene terephthalate) cold-crystallized\nfrom either an isotropic or an oriented glass. It is found that in the latter\ncase the regions of cooperative rearrangement are significantly larger than in\nthe former."
    },
    {
        "anchor": "Effect of entropy on the dynamics of supercooled liquids: New results\n  from high pressure data: We show that for arbitrary thermodynamic conditions, master curves of the\nentropy are obtained by expressing S(T,V) as a function of TV^g_G, where T is\ntemperature, V specific volume, and g_G the thermodynamic Gruneisen parameter.\nA similar scaling is known for structural relaxation times,tau = f(TV^g);\nhowever, we find g_G < g. We show herein that this inequality reflects\ncontributions to S(T,V) from processes, such as vibrations and secondary\nrelaxations, that do not directly influence the supercooled dynamics. An\napproximate method is proposed to remove these contributions, S_0, yielding the\nrelationship tau = f(S-S_0).",
        "positive": "Stiff quantum polymers: At ultralow temperatures, polymers exhibit quantum behavior, which is\ncalculated here for the second and fourth moments of the end-to-end\ndistribution in the large-stiffness regime. The result should be measurable for\npolymers in wide optical traps."
    },
    {
        "anchor": "Conical soliton escape into a third dimension of a surface vortex: We present an exact three-dimensional solitonic solution to a\nsine-Gordon-type Euler-Lagrange equation, that describes a configuration of a\nthree-dimensional vector field n constrained to a surface p-vortex, with a\nprescribed polar tilt angle on a planar substrate and escaping into the third\ndimension in the bulk. The solution is relevant to characterization of a\nschlieren texture in nematic liquid-crystal films with tangential (in-plane)\nsubstrate alignment. The solution is identical to a section of a point defect\ndiscovered many years ago by Saupe [Mol. Cryst. Liq. Cryst. 21, 211 (1973)],\nwhen latter is restricted to a surface.",
        "positive": "Molecular dynamics simulations of shear-induced thermophoresis and\n  non-Newtonian flow in compressible fluids: We use molecular dynamics simulations to study the behavior of a compressible\nLennard-Jones fluid in simple shear flow in a two-dimensional nanochannel. The\nsystem is equilibrated in the fluid phase close to the triple point at which\ngas, liquid and solid phases coexist and is subjected to steady shear in\nCouette geometry. It is observed that at higher shear rates, the system\ndevelops a density gradient perpendicular to the direction of flow and exhibits\nsolid-like layering near the boundaries. Both the number of solid-like layers\nand the number of layers that move with the velocity of the neighboring wall,\nincrease with the shear rate. We argue that the inhomogeneous density profile\ndevelops as the consequence of thermophoresis due to the non-uniform\ntemperature profile produced by shear-induced viscous heating in the simulated\nflow cell. The above phenomena are accompanied by non-Newtonian effects such as\nnonlinear velocity profiles, inhomogeneous stress distributions and shear rate\ndependent viscosity which exhibits shear thinning followed by shear thickening\nas the shear rate is increased. The connection between these phenomena is\ndiscussed."
    },
    {
        "anchor": "Understanding Creep Suppression Mechanism in Polymer Nanocomposites\n  through Machine Learning: While recent efforts have shown how local structure plays an essential role\nin the dynamic heterogeneity of homogeneous glass-forming materials, systems\ncontaining interfaces such as thin films or composite materials remain poorly\nunderstood. It is known that interfaces perturb the molecular packing nearby,\nhowever, numerous studies show the dynamics are modified over a much larger\nrange. Here, we examine the dynamics in polymer nanocomposites (PNCs) using a\ncombination of simulations and experiments and quantitatively separate the role\nof polymer packing from other effects on the dynamics, as a function of\ndistance from the nanoparticle surfaces. After showing good qualitative\nagreement between the simulations and experiments in glassy structure and creep\ncompliance, we use a recently developed machine learning technique to decompose\npolymer dynamics in our simulated PNCs into structure-dependent and\nstructure-independent processes. With this decomposition, the free energy\nbarrier for polymer rearrangement can be described as a combination of\npacking-dependent and packing-independent barriers. We find both barriers are\nhigher near nanoparticles and decrease with applied stress, quantitatively\ndemonstrating that the slow interfacial dynamics is not solely due to polymer\npacking differences, but also the change of structure-dynamics relationships.\nFinally, we present how this decomposition can be used to accurately predict\nstrain-time creep curves for PNCs from their static configuration, providing\nadditional insights into the effects of polymer-nanoparticle interfaces on\ncreep suppression in PNCs.",
        "positive": "Dynamics of lattice pinned charge stripes: We study the transversal dynamics of a charged stripe (quantum string) and\nshow that zero temperature quantum fluctuations are able to depin it from the\nlattice. If the hopping amplitude t is much smaller than the string tension J,\nthe string is pinned by the underlying lattice. At t>>J, the string is depinned\nand allowed to move freely, if we neglect the effect of impurities. By mapping\nthe system onto a 1D array of Josephson junctions, we show that the quantum\ndepinning occurs at t/J = 2 / pi^2. Besides, we exploit the relation of the\nstripe Hamiltonian to the sine-Gordon theory and calculate the infrared\nexcitation spectrum of the quantum string for arbitrary t/J values."
    },
    {
        "anchor": "Transition from viscous fingers to foam during drainage in heterogeneous\n  porous media: We investigate the behavior of drainage displacements in heterogeneous porous\nmedia finding a transition from viscous fingering to foam-like region. A pore\nnetwork model incorporating the formation of blobs is adopted to study this\nphenomenon. By imposing a pressure difference between the inlet and outlet, we\nobserve that the displacement pattern undergoes a significant transition from a\ncontinuous front of growing viscous fingers to the emergence of foam, which\ndevelops and propagates until breakthrough. This transition occurs at a\nspecific distance from the inlet, which we measure and analyze as a function of\nthe viscosity ratio and the capillary number, demonstrating that it follows a\nnon-trivial power-law decay with both the parameters. Moreover, we discuss the\nrelationship between the evolution of the total flow rate and the local\npressure drop, showing that the foam developed reduces global mobility. We\nobserve that foam is formed from the fragmentation of viscous fingers beneath\nthe front, and this instability mechanism is connected with fluctuations of the\nlocal flow rate, which we analyze both in the viscous fingering region and in\nthe foam region.",
        "positive": "High resolution x-ray study of nematic-smectic-A and Smectic-A-reentrant\n  nematic transitions in liquid crystal+aerosil gels: We have studied the effects of quenched random disorder created by dispersed\naerosil nanoparticle gels on the nematic to smectic-A (N-SmA) and smectic-A to\nreentrant nematic (SmA- RN) phase transitions of thermotropic liquid crystal\nmixtures of 6OCB (hexyloxycyanobiphenyl) and 8OCB (octyloxycyanobiphenyl).\nThese effects are probed using high-resolution synchrotron x-ray diffraction\ntechniques. We find that the reentrant characteristics of the system are\nlargely unchanged by the presence of the aerosil gel network. By comparing\nmeasurements of the smectic static structure amplitude for this\n8OCB-6OCB+aerosil system with those for butyloxybenzilidene-octylaniline\n(4O.8)+aerosil gels, we find that the short-range smectic order in the\nsmectic-A phase is significantly weaker in the reentrant system. This result is\nconsistent with the behavior seen in pure 8OCB-6OCB mixtures. The strength of\nthe smectic ordering decreases progressively as the 6OCB concentration is\nincreased. Detailed line shape analysis shows that the high- and\nlow-temperature nematic phases (N and RN) are similar to each other."
    },
    {
        "anchor": "Translocation of stiff polymers through a nanopore driven by binding\n  particles: We investigate the translocation of stiff polymers in the presence of binding\nparticles through a nanopore by two-dimensional Langevin dynamics simulations.\nWe find that the mean translocation time shows a minimum as a function of the\nbinding energy $\\epsilon$ and the particle concentration $\\phi$, due to the\ninterplay of the force from binding and the frictional force. Particularly, for\nthe strong binding the translocation proceeds with a decreasing translocation\nvelocity induced by a significant increase of the frictional force. In\naddition, both $\\epsilon$ and $\\phi$ have an notable impact on the distribution\nof the translocation time. With increasing $\\epsilon$ and $\\phi$, it undergoes\na transition from an asymmetric and broad distribution under the weak binding\nto a nearly Gaussian one under the strong binding, and its width becomes\ngradually narrower.",
        "positive": "Gel-forming patchy colloids and network glass formers: Thermodynamic and\n  Dynamic analogies: This article discusses recent attempts to provide a deeper understanding of\nthe thermoreversible \"gel\" state of colloidal matter and to unravel the\nanalogies between gels at the colloidal level and gels at the molecular level,\ncommonly known as network-forming strong liquids. The connection between\ngel-forming patchy colloids and strong liquids is provided by the limited\nvalence of the inter-particle interactions, i.e. by the presence of a limit in\nthe number of bonded nearest neighbors."
    },
    {
        "anchor": "Measuring Gaussian rigidity using curved substrates: The Gaussian (saddle splay) rigidity of fluid membranes controls their\nequilibrium topology but is notoriously difficult to measure. In lipid\nmixtures, typical of living cells, linear interfaces separate liquid ordered\n(LO) from liquid disordered (LD) bilayer phases at subcritical temperatures.\nHere we consider such membranes supported by curved supports that thereby\ncontrol the membrane curvatures. We show how spectral analysis of the\nfluctuations of the LO-LD interface provides a novel way of measuring the\ndifference in Gaussian rigidity between the two phases. We provide a number of\nconditions for such interface fluctuations to be both experimentally measurable\nand sufficiently sensitive to the value of the Gaussian rigidity, whilst\nremaining in the perturbative regime of our analysis.",
        "positive": "The many-body reciprocal theorem and swimmer hydrodynamics: We present a reinterpretation and extension of the reciprocal theorem for\nswimmers, extending its application from the motion of a single swimmer in an\nunbounded domain to the general setting, giving results for both swimmer\ninteractions and general hydrodynamics. We illustrate the method for a squirmer\nnear a planar surface, recovering standard literature results and extending\nthem to a general squirming set, to motion in the presence of a ciliated\nsurface, and expressions for the flow field throughout the domain. Finally, we\npresent exact results for the hydrodynamics in two dimensions which shed light\non the near-field behaviour."
    },
    {
        "anchor": "On the stability and growth of single myelin figures: Myelin figures are long thin cylindrical structures that typically grow as a\ndense tangle when water is added to the concentrated lamellar phase of certain\nsurfactants. We show that, starting from a well-ordered initial state, single\nmyelin figures can be produced in isolation thus allowing a detailed study of\ntheir growth and stability. These structures grow with their base at the\nexposed edges of bilayer stacks from which material is transported into the\nmyelin. Myelins only form and grow in the presence of a driving stress; when\nthe stress is removed, the myelins retract.",
        "positive": "Role of length-polydispersity on the phase behavior of freely-rotating\n  hard-rectangle fluid: We used the Density Functional formalism, in particular the Scaled Particle\nTheory, applied to a length-polydisperse hard-rectangular fluid to study its\nphase behavior as a function of the mean particle aspect ratio ($\\kappa_0$) and\npolydispersity ($\\Delta_0$). The numerical solutions of the coexistence\nequations were calculated by transforming the original problem with infinite\ndegrees of freedoms to a finite set of equations for the amplitudes of the\nFourier expansion of the moments of the density profiles. We divided the study\ninto two parts: The first one is devoted to the calculation of the phase\ndiagrams in the packing fraction ($\\eta_0$)- $\\kappa_0$ plane for a fixed\n$\\Delta_0$ and selecting parent distribution functions with exponential (the\nSchulz distribution) or Gaussian decays. In the second part we study the phase\nbehavior in the $\\eta_0$-$\\Delta_0$ plane for fixed $\\kappa_0$ while $\\Delta_0$\nis changed. We characterize in detail the orientational ordering of particles\nand the fractionation of different species between the coexisting phases. Also\nwe study the character (second vs. first order) of the Isotropic-Nematic phase\ntransition as a function of polydispersity. We particularly focused on the\nstability of the Tetratic phase as a function of $\\kappa_0$ and $\\Delta_0$. The\nIsotropic-Nematic transition becomes strongly of first order when\npolydispersity is increased: the coexisting gap widens and the location of the\ntricritical point moves to higher values of $\\kappa_0$ while the Tetratic phase\nis slightly destabilized with respect to the Nematic one. The results obtained\nhere can be tested in experiments on shaken monolayers of granular rods."
    },
    {
        "anchor": "Information conduction and convection in noiseless Vicsek flocks: Physical interactions generally respect certain symmetries, such as\nreciprocity and energy conservation, which survive in coarse grained isothermal\ndescriptions. Active many-body systems usually break such symmetries\nintrinsically, on the particle level, so that their collective behavior is\noften more naturally interpreted as a result of information exchange. Here, we\nstudy numerically how information spreads from a \"leader\" particle through an\ninitially aligned flock, described by the Vicsek model without noise. In the\nlow-speed limit of a static spin lattice, we find purely conductive spreading,\nreminiscent of heat transfer. Swarm motility and heterogeneity can break\nreciprocity and spin conservation. But what seems more consequential for the\nswarm response is that the dispersion relation acquires a significant\nconvective contribution along the leader's direction of motion.",
        "positive": "Friction of polymers: from PDMS melts to PDMS elastomers: The slip behavior of polydimethylsiloxane (PDMS) polymer melts flowing on\nnon-adsorbing surfaces made of short non-entangled PDMS chains densely\nend-grafted to silica has been characterized. For high enough shear rates,\nconstant slip lengths proportional to the bulk fluid viscosity have been\nobserved, in agreement with Navier's interfacial equation, and demonstrating\nthat the interfacial Navier's friction coefficient is a local quantity,\nindependent of the polymer molecular weight. Comparing the interfacial shear\nstresses deduced from these measured slip lengths to available friction stress\nmeasured for crosslinked PDMS elastomers, we directly compared the interfacial\nmelt or elastomer friction coefficient to the monomer-monomer friction."
    },
    {
        "anchor": "Bistability and equilibria of creased annular sheets and strips: A creased thin disk is generally bistable since the crease could be pushed\nthrough to form a stable cone-like inverted state with an elastic singularity\ncorresponding to the vertex of the conical surface. In a recent study, we found\nthat this bistability could be destroyed by removing the singularity through\ncutting a hole around the vertex, depending on the size and shape of the hole.\nThis paper extends our recent work and is based on the following observations\nin tabletop models of creased disks with circular holes: (i) reducing the\ncircumference of the creased disk by removing an annular sector could increase\nthe hole size to be as large as the disk without destroying the bistability,\n(ii) with a single crease, the circular hole could be as large as the disk\nwithout loss of the bistability, and (iii) a family of stable inverted states\ncan be obtained by inverting the disk almost anywhere along the crease. An\ninextensible strip model is implemented to investigate these phenomena. We\nformulate a minimal facet of the creased disk as a two-point boundary value\nproblem with the creases modeled as nonlinear hinges, and use numerical\ncontinuation to conduct parametric studies. Specifically, we focus on geometric\nparameters which include an angle deficit that determines the circumference of\nthe disk, the rest crease angle, the number of evenly distributed creases, and\nan eccentricity that determines the position of the hole on the crease. Our\nnumerical results confirm the qualitative observations in (i)-(iii) and further\nreveal unexpected results caused by the coupling between these geometric\nparameters. Our results demonstrate that by varying the geometry of a simply\ncreased disk, surprisingly rich nonlinear behaviors can be obtained, which shed\nnew light on the mechanics and design of origami, kirigami, and morphable\nstructures.",
        "positive": "Contact tribology also affects the slow flow behavior of granular\n  emulsions: Recent work on suspension flows has shown that contact mechanics plays a role\nin suspension flow dynamics. The contact mechanics between particulate matter\nin dispersions should depend sensitively on the composition of the dispersed\nphase: evidently emulsion droplets interact differently with each other than\nangular sand particles. We therefore ask: what is the role of contact mechanics\nin dispersed media flow? We focus on slow flows, where contacts are\nlong-lasting and hence contact mechanics effects should be most visible. To\nanswer our question, we synthesize soft hydrogel particles with different\nfriction coefficients. By making the particles soft, we can drive them at\nfinite confining pressure at all driving rates. For particles with a low\nfriction coefficient, we obtain a rheology similar to that of an emulsion, yet\nwith an effective friction much larger than expected from their microscopic\ncontact mechanics. Increasing the friction coefficient of the particles, we\nfind a flow instability in the suspension. Particle level flow and fluctuations\nare also greatly affected by the microscopic friction coefficient of the\nsuspended particles. The specific rheology of our \"granular emulsions\" provides\nfurther evidence that a better understanding of microscopic particle\ninteractions is of broad relevance for dispersed media flows."
    },
    {
        "anchor": "Unexpected spatial distribution of bubble rearrangements in coarsening\n  foams: Foams are ideal model systems to study stress-driven dynamics, as\nstress-imbalances within the system are continuously generated by the\ncoarsening process, which unlike thermal fluctuations, can be conveniently\nquantified by optical means. However, the high turbidity of foams generally\nhinders the detailed study of the temporal and spatial distribution of\nrearrangement events, such that definite assessments regarding their\ncontribution to the overall dynamics could not be made so far. In this paper,\nwe use novel light scattering techniques to measure the frequency and position\nof events within a large sample volume. As recently reported (A. S. Gittings\nand D. J. Durian, Phys. Rev. E, 2008, 78, 066313), we find that the foam\ndynamics is determined by two distinct processes: intermittent bubble\nrearrangements of finite duration and a spatially homogeneous quasicontinuous\nprocess. Our experiments show that the convolution of these two processes\ndetermines the age-dependence of the mean dynamics, such that relations between\nintermittent rearrangements and coarsening process can not be established by\nconsidering means. By contrast the use of the recently introduced photon\ncorrelation imaging technique (A. Duri, D. A. Sessoms, V. Trappe, and L.\nCipelletti, Phys. Rev. Lett., 2009, 102, 085702) enables us to assess that the\nevent frequency is directly determined by the strain-rate imposed by the\ncoarsening process. Surprisingly, we also find that, although the distribution\nof successive events in time is consistent with a random process, the spatial\ndistribution of successive events is not random: rearrangements are more likely\nto occur within a recently rearranged zone. This implies that a topological\nrearrangement is likely to lead to an unstable configuration, such that a small\namount of coarsening-induced strain is sufficient to trigger another event.",
        "positive": "The Deformation of an Elastic Substrate by a Three-Phase Contact Line: Young's classic analysis of the equilibrium of a three-phase contact line\nignores the out-of-plane component of the liquid-vapor surface tension. While\nit has long been appreciated that this unresolved force must be balanced by\nelastic deformation of the solid substrate, a definitive analysis has remained\nelusive because conventional idealizations of the substrate imply a divergence\nof stress at the contact line. While a number of theories of have been\npresented to cut off the divergence, none of them have provided reasonable\nagreement with experimental data. We measure surface and bulk deformation of a\nthin elastic film near a three-phase contact line using fluorescence confocal\nmicroscopy. The out-of-plane deformation is well fit by a linear elastic theory\nincorporating an out-of-plane restoring force due to the surface tension of the\ngel. This theory predicts that the deformation profile near the contact line is\nscale-free and independent of the substrate elastic modulus."
    },
    {
        "anchor": "Structural changes of diblock copolymer melts due to an external\n  electric field: a self-consistent field theory study: We study the phase behavior of diblock copolymers in presence of an external\nelectric field. We employ self-consistent field theory and treat the relevant\nMaxwell equation as an additional self-consistent equation. Because we do not\ntreat the electric field perturbatively, we can examine its effects even when\nits magnitude is large. The electric field couples to the system's morphology\nonly through the difference between the dielectric constants of the two blocks.\nWe find that an external field aligns a body-centered cubic phase along the\n(111) direction, reducing its symmetry group to $R{\\bar 3}m$. Transitions\nbetween this phase and the disordered or hexagonal phases can occur for\nexternal electric fields ranging from a minimum to a maximum value beyond which\nthe $R{\\bar 3m}$ phase disappears completely. This electric-field range depends\non diblock architecture and temperature. We present several cuts through the\nphase diagram in the space of temperature, architecture and applied field,\nincluding one applicable to a system recently studied.",
        "positive": "Crystallization and arrest mechanisms of model colloids: We performed dynamic simulations of spheres with short-range attractive\ninteractions for many values of interaction strength and range. Fast\ncrystallization occurs in a localized region of this parameter space, but the\ncharacter of crystallization pathways is not uniform within this region.\nPathways range from one-step, in which a crystal nucleates directly from a gas,\nto two-step, in which substantial liquid-like clusters form and only\nsubsequently become crystalline. Crystallization can fail because of slow\nnucleation from either gas or liquid, or because of dynamic arrest caused by\nstrong interactions. Arrested states are characterized by the formation of\nnetworks of face-sharing tetrahedra that can be detected by a local common\nneighbor analysis."
    },
    {
        "anchor": "Computer simulation of random loose packings of micro-particles in\n  presence of adhesion and friction: With a novel 3D discrete-element method specially developed with adhesive\ncontact mechanics, random loose packings of uniform spherical micron-sized\nparticles are fully investigated. The results show that large velocity, large\nsize or weak adhesion can produce a relatively dense packing when other\nparameters are fixed, and these combined effects can be characterized by a\ndimensionless adhesion parameter ( $Ad=\\omega/2\\rho_pU^2_0R$). Four regimes are\nidentified based on the value of $Ad$: RCP regime with $Ad<\\sim 0.01$; RLP\nregime with $\\sim 0.01<Ad<1$; adhesion regime with $1<Ad<20$ and an asymptotic\nregime with $Ad>20$. Force distribution of these adhesive loose packings\nfollows $P(f)\\sim f^\\theta$ for small forces and $P(f)\\sim \\exp^{-\\beta f}$ for\nbig forces, respectively, which shares a similar form with that in packings\nwithout adhesion but results in distinct exponents of $\\theta=0.879$,\n$\\beta=0.839$. A local mechanical equilibrium analysis shows that adhesion\nenhances both sliding and rolling resistance so that fewer neighbours are\nneeded to satisfy the force and torque balance.",
        "positive": "Thermodynamic equilibrium of binary mixtures on curved surfaces: We study the global influence of curvature on the free energy landscape of\ntwo-dimensional binary mixtures confined on closed surfaces. Starting from a\ngeneric effective free energy, constructed on the basis of symmetry\nconsiderations and conservation laws, we identify several model-independent\nphenomena, such as a curvature-dependent line tension and local shifts in the\nbinodal concentrations. To shed light on the origin of the phenomenological\nparameters appearing in the effective free energy, we further construct a\nlattice-gas model of binary mixtures on non-trivial substrates, based on the\ncurved-space generalization of the two-dimensional Ising model. This allows us\nto decompose the interaction between the local concentration of the mixture and\nthe substrate curvature into four distinct contributions, as a result of which\nthe phase diagram splits into critical sub-diagrams. The resulting free energy\nlandscape can admit, as stable equilibria, strongly inhomogeneous mixed phases,\nwhich we refer to as antimixed states below the critical temperature. We\ncorroborate our semi-analytical findings with phase-field numerical simulations\non realistic curved lattices. Despite this work being primarily motivated by\nrecent experimental observations of multi-component lipid vesicles supported by\ncolloidal scaffolds, our results are applicable to any binary mixture confined\non closed surfaces of arbitrary geometry."
    },
    {
        "anchor": "Active instability and nonlinear dynamics of cell-cell junctions: Active cell-junction remodeling is important for tissue morphogenesis, yet\nits underlying physics is not understood. We study a mechanical model that\ndescribes junctions as dynamic active force dipoles. Their instability can\ntrigger cell intercalations by a critical collapse. Nonlinearities in tissue's\nelastic response can stabilize the collapse either by a limit cycle or\ncondensation of junction lengths at cusps of the energy landscape. Furthermore,\nactive junction networks undergo collective instability to drive active\nin-plane ordering or develop a limit cycle of collective oscillations, which\nextends over regions of the energy landscape corresponding to distinct network\ntopologies.",
        "positive": "Model fluid in a porous medium: results for a Bethe lattice: We consider a lattice gas with quenched impurities or `quenched-annealed\nbinary mixture' on the Bethe lattice. The quenched part represents a porous\nmatrix in which the (annealed) lattice gas resides. This model features the 3\nmain factors of fluids in random porous media: wetting, randomness and\nconfinement. The recursive character of the Bethe lattice enables an exact\ntreatment, whose key ingredient is an integral equation yielding the\none-particle effective field distribution. Our analysis shows that this\ndistribution consists of two essentially different parts. The first one is a\ncontinuous spectrum and corresponds to the macroscopic volume accessible to the\nfluid, the second is discrete and comes from finite closed cavities in the\nporous medium. Those closed cavities are in equilibrium with the bulk fluid\nwithin the grand canonical ensemble we use, but are inaccessible in real\nexperimental situations. Fortunately, we are able to isolate their\ncontributions. Separation of the discrete spectrum facilitates also the\nnumerical solution of the main equation. The numerical calculations show that\nthe continuous spectrum becomes more and more rough as the temperature\ndecreases, and this limits the accuracy of the solution at low temperatures."
    },
    {
        "anchor": "Displays and antiferroelectric liquid crystals: Recently we have formulated theory of bi-layer-dimerized chiral liquid\nantiferroelectric crystals. The spontaneous polarization has been increased\nowing to the strong interaction of the aromatic cores of the rod like liquid\ncrystal molecules with the honey-comb pattern of the CNT walls The SmC*A\nordering is improved around the CNTs. All relaxation modes in each phase are\nfacilitated by dispersion of nanotubes whicg enhances the relaxation\nfrequencies. This composite system with improvement in electro-optical\nproperties can be exploited in modern display applications. SmC* LC were\nstudied by one of t he authors (OH), namely their transition from the SmC\nphase. The role of disclinations in an applied electric field was studied by O.\nHudak in the SmC* structure. While the role of fluctuations and of\ndisclinations in the SmC* (FLC)was studied in the above papers, the role of\nfluctuations and disclinations in SmC*A and the role of addition of MWCNTs in\nSmC*A phaseis not well understood. Our theoretical description of (AFLC)\nincluding SmC*A introduced in may thus be used to study these effects.",
        "positive": "Explosion cratering in 3D granular media: Sudden release of energy in explosion creates craters in granular media. In\ncomparison with well-studied impact cratering in granular media, our\nunderstanding of explosion cratering is still primitive. Here, we study\nlow-energy lab-scale explosion cratering in 3D granular media using controlled\npulses of pressurized air. We identify four regimes of explosion cratering at\ndifferent burial depths, which are associated with distinct explosion dynamics\nand result in different crater morphologies. We propose a general relation\nbetween the dynamics of granular flows and the surface structures of resulting\ncraters. Moreover, we measure the diameter of explosion craters as a function\nof explosion pressures, durations and burial depths. We find that the size of\ncraters is non-monotonic with increasing burial depths, reaching a maximum at\nan intermediate burial depth. In addition, the crater diameter shows a weak\ndependence on explosion pressures and durations at small burial depths. We\nconstruct a simple model to explain this finding. Finally, we explore the\nscaling relations of the size of explosion craters. Despite the huge difference\nin energy scales, we find that the diameter of explosion craters in our\nexperiments follows the same cube root energy scaling as explosion cratering at\nhigh energies. We also discuss the dependence of rescaled crater sizes on the\ninertial numbers of granular flows. These results shed light onto the rich\ndynamics of 3D explosion cratering and provide new insights into the general\nphysical principles governing granular cratering processes."
    },
    {
        "anchor": "Direction-dependent Dynamics of Colloidal Particle Pairs and the\n  Stokes-Einstein Relation in Quasi-Two-Dimensional Fluids: Hydrodynamic interactions are important for diverse fluids especially those\nwith low Reynold's number such as microbial and particle-laden suspensions, and\nproteins diffusing in membranes. Unfortunately, while far-field (asymptotic)\nhydrodynamic interactions are fully understood in two- and three-dimensions,\nnear-field interactions are not, and thus our understanding of motions in dense\nfluid suspensions is still lacking. In this contribution, we experimentally\nexplore the hydrodynamic correlations between particles in\nquasi-two-dimensional colloidal fluids in the near-field. Surprisingly, the\nmeasured displacement and relaxation of particle pairs in the body frame\nexhibit direction-dependent dynamics that can be connected quantitatively to\nthe measured near-field hydrodynamic interactions. These findings, in turn,\nsuggest a mechanism for how and when hydrodynamics can lead to a breakdown of\nthe ubiquitous Stokes-Einstein relation (SER). We observe this breakdown, and\ninterestingly, we show that the direction-dependent breakdown of the SER is\nameliorated along directions where hydrodynamic correlations are smallest. In\ntotal, the work uncovers significant ramifications of near-field hydrodynamics\non transport and dynamic restructuring of fluids in two-dimensions.",
        "positive": "Statistical signature of vortex filaments: dog or tail? Talk given at\n  QFS 2016: The title of the paper coincides with the title of a paragraph in the famous\nbook by U. Frisch (1995)on classical turbulence. In this paragraph the author\ndiscussed the role of statistical dynamics of vortex filaments in the theory of\nturbulence and put the above question. In other words, whether the main\nproperties of turbulence (cascade, scaling laws) are the sequence of the vortex\nline dynamics or the latter have only marginal signature. Quantum fluids, where\nthe vortex filaments are the real objects, give an excellent opportunity to\nexplore the role of discrete vortices in turbulent phenomena. The aim of this\npaper is to discuss which elements of vortex dynamics would lead to the main\ningredients of the theory of turbulence. We discuss how the nonlinear dynamics\nof vortex filaments can result in an exchange of energy between different\nscales, the formation of the Kolmogorov-type energy spectra and the decay of\nturbulence."
    },
    {
        "anchor": "Localization and size distribution of a polymer knot confined in a\n  channel: We have examined the behaviors of a knotted linear polymer in narrow tubes\nusing Langevin dynamics simulation to investigate the knot localization\nproperty in one-dimensional (1D) geometry. We have found that the knot is\nstrongly localized in such a geometry. By observing the distribution function\nof the size of localized knot, we found the scaling behavior of the fluctuation\naround the most probable size with radius of confinement. Based on the analysis\nof the probability distribution of the knot size, we show that the strong\nlocalization behavior and the fluctuation around the most probable size can be\nencompassed by a simple argument based on the virtual tubes composed of\nparallel strands and overlapping among them.",
        "positive": "Upstream swimming in microbiological flows: Interactions between microorganisms and their complex flowing environments\nare essential in many biological systems. We develop a model for microswimmer\ndynamics in non-Newtonian Poiseuille flows. We predict that swimmers in\nshear-thickening (-thinning) fluids migrate upstream more (less) quickly than\nin Newtonian fluids and demonstrate that viscoelastic normal stress differences\nreorient swimmers causing them to migrate upstream at the centreline, in\ncontrast to well-known boundary accumulation in quiescent Newtonian fluids.\nBased on these observations, we suggest a sorting mechanism to select microbes\nby swimming speed."
    },
    {
        "anchor": "Adsorption from binary solutions on chemically bonded phases: We use density functional theory to investigate adsorption of liquid mixtures\non solid surfaces modified with end-grafted chains. The chains are modelled as\nfreely joined spheres. The fluid molecules are spherical. All spherical species\ninteract via the Lennard-Jones (12-6) potential. The Lennard-Jones (9-3)\npotential describes interactions of solvent molecules with the substrate. We\nstudy the relative excess adsorption isotherms, the structure of surface layer\nand its composition. The impact of the following parameters on adsorption is\ndiscussed: the grafting density, the grafted chain length, interactions of\nsolvent molecules with grafted chains and with the substrate, and the presence\nof active groups in grafted chains. The theoretical results are consistent with\nexperimental observations.",
        "positive": "Commentary on: \"Unconventional elasticity in smectic-A elastomers\" by O.\n  Stenull and T.C. Lubensky: The reorientation behaviour of a smectic-A (SmA) elastomer deformed parallel\nto the smectic layer normal has been interpreted as a Sm-C like transition by\nStenull and Lubensky. Experiments, however, prove that such a transition does\nnot occur."
    },
    {
        "anchor": "Surface-directed Dynamics in Living Liquid Crystals: We study living liquid crystals (LLCs), which are an amalgam of nematic\nliquid crystals (LCs) and active matter (AM). These LLCs are placed in contact\nwith surfaces which impose planar/homeotropic boundary conditions on the\ndirector field of the LC and the polarization field of the AM. The interplay of\nLC-AM interactions and the surface-directed conditions yield controlled pattern\ndynamics in the LLC, which has important technological implications. We discuss\ntwo representative examples of this pattern dynamics.",
        "positive": "Relating Microstructure and Particle-level Stress in Colloidal Crystals\n  Under Increased Confinement: The mechanical properties of crystalline materials can be substantially\nmodified under confinement. Such modified macroscopic properties are usually\ngoverned by the altered microstructures and internal stress fields. Here, we\nuse a parallel plate geometry to apply a quasi-static squeeze flow crushing a\ncolloidal polycrystal while simultaneously imaging it with confocal microscopy.\nThe confocal images are used to quantify the local structure order and, in\nconjunction with Stress Assessment from Local Structural Anisotropy (SALSA),\ndetermine the stress at the single-particle scale. We find that during\ncompression, the crystalline regions break into small domains with different\ngeometric packing. These domains are characterized by a pressure and deviatoric\nstress that are highly localized with correlation lengths that are half those\nfound in bulk. Furthermore, the mean deviatoric stress almost doubles,\nsuggesting a higher brittleness in the highly-confined samples."
    },
    {
        "anchor": "Collective oscillations of a 1D trapped Bose gas: Starting from the hydrodynamic equations of superfluids, we calculate the\nfrequencies of the collective oscillations of a harmonically trapped Bose gas\nfor various 1D configurations. These include the mean field regime described by\nGross-Pitaevskii theory and the beyond mean field regime at small densities\ndescribed by Lieb-Liniger theory. The relevant combinations of the physical\nparameters governing the transition between the different regimes are\ndiscussed.",
        "positive": "Phase Ordering in Nematic Liquid Crystals: We study the kinetics of the nematic-isotropic transition in a\ntwo-dimensional liquid crystal by using a lattice Boltzmann scheme that couples\nthe tensor order parameter and the flow consistently. Unlike in previous\nstudies, we find the time dependences of the correlation function, energy\ndensity, and the number of topological defects obey dynamic scaling laws with\ngrowth exponents that, within the numerical uncertainties, agree with the value\n1/2 expected from simple dimensional analysis. We find that these values are\nnot altered by the hydrodynamic flow. In addition, by examining shallow\nquenches, we find that the presence of orientational disorder can inhibit\namplitude ordering."
    },
    {
        "anchor": "On the theory of electric double layer with explicit account of a\n  polarizable co-solvent: We present a continuation of our theoretical research into the influence of\nco-solvent polarizability on a differential capacitance of the electric double\nlayer [EPL 111, 28002 (2015)]. We formulate a modified Poisson-Boltzmann\ntheory, using the formalism of density functional approach on the level of\nlocal density approximation taking into account the electrostatic interactions\nof ions and co-solvent molecules as well as their excluded volume. We derive\nthe modified Poisson-Boltzmann equation, considering the three-component\nsymmetric lattice gas model as a reference system and minimizing the grand\nthermodynamic potential with respect to the electrostatic potential. We apply\npresent modified Poisson-Boltzmann equation to the electric double layer\ntheory.",
        "positive": "Rectification and non-Gaussian diffusion in heterogeneous media: We show that when Brownian motion takes place in a heterogeneous medium, the\npresence of local forces and transport coefficients leads to deviations from a\nGaussian probability distribution that make that the ratio between forward and\nbackward probabilities depends on the nature of the host medium, on local\nforces and also on time. We have applied our results to two situations:\ndiffusion in a disordered medium and diffusion in a confined system. For such\nscenarios we have shown that our theoretical predictions are in very good\nagreement with numerical results. Moreover we have shown that the deviations\nfrom the Gaussian solution lead to the onset of rectification. Our predictions\ncould be used to detect the presence of local forces and to characterize the\nintrinsic short-scale properties of the host medium, a problem of current\ninterest in the study of micro and nano-systems."
    },
    {
        "anchor": "Drag force on cylindrical intruders in granular media: Experimental\n  study of lateral vs axial intrusion and high grain-polydispersity effects: We report on experimentally measured drag force experienced by a solid\ncylinder penetrating a granular bed of glass beads including, specifically, a\nhighly polydisperse sample with grain sizes in the range 1-100 {\\mu}m. We\nconsider both cases of lateral and axial intrusion in which the long axis of\nthe cylinder is held horizontally and vertically, respectively. We explore\ndifferent regimes of behavior for the drag force as a function of the\npenetration depth. In lateral intrusion, where the motion is effectively\nquasi-two-dimensional, we establish quantitative comparisons with existing\ntheoretical predictions across the whole range of depths. In axial intrusion,\nwe observe peculiar undulations in the force-depth profiles in a wide range of\nintrusion speeds and for different cylinder diameters. We argue that these\nundulations reflect general shear failure in the highly polydisperse sample and\ncan be understood based on the ultimate bearing capacity theory on a\nsemiquantitative level.",
        "positive": "Soft deformable self-propelled particles: In this work we investigate the collective behavior of self-propelled\nparticles that deform due to local pairwise interactions. We demonstrate that\nthis deformation alone can induce alignment of the velocity vectors. The onset\nof collective motion is analyzed. Applying a Gaussian-core repulsion between\nthe particles, we find a transition to disordered non-collective motion under\ncompression. We here explain that this reflects the reentrant fluid behavior of\nthe general Gaussian-core model now applied to a self-propelled system.\nTruncating the Gaussian potential can lead to cluster crystallization or more\ndisordered cluster states. For intermediate values of the Gaussian-core\npotential we for the first time observe laning for deformable self-propelled\nparticles. Finally, without the core potential, but including orientational\nnoise, we connect our description to the Vicsek approach for self-propelled\nparticles with nematic alignment interactions."
    },
    {
        "anchor": "Non-equilibrium electric double layers at the interface between two\n  electrolytes: The charge distribution at the interface between two electrolytes is studied\nfor the case of non-vanishing ion fluxes. The analysis is an extension of the\nestablished Verwey-Niessen theory to non-equilibrium situations. Applying\nmatched asymptotic expansions for the region of the electric double layer and\nthe bulk electrolytes, analytical expressions for the ion concentrations and\nthe electrostatic potential are derived. It is found that the electric double\nlayer is surprisingly stable. Even in cases where the applied electric field is\nso strong that it completely cancels the field of the charge clouds at the\ninterface, two opposing space charge regions are formed. This phenomenon is\nqualitatively explained using a simple model incorporating ion partitioning and\ndiffusive ion transport. Another notable phenomenon is that the interface\nacquires a net charge in the presence of an applied electric field, being of\nrelevance for the hydrodynamic stability of interfacial flows.",
        "positive": "Hydrodynamics of the Kuramoto-Sivashinsky Equation in Two Dimensions: The large scale properties of spatiotemporal chaos in the 2d\nKuramoto-Sivashinsky equation are studied using an explicit coarse graining\nscheme. A set of intermediate equations are obtained. They describe\ninteractions between the small scale (e.g., cellular) structures and the\nhydrodynamic degrees of freedom. Possible forms of the effective large scale\nhydrodynamics are constructed and examined. Although a number of different\nuniversality classes are allowed by symmetry, numerical results support the\nsimplest scenario, that being the KPZ universality class."
    },
    {
        "anchor": "Numerical simulation of the twist-grain-boundary phase of chiral liquid\n  crystals: We study the core structure of the twist-grain-boundary (TGB) phase of chiral\nliquid crystals by numerically minimizing the Landau-de Gennes free energy. We\nanalyze the morphology of layers at the grain boundary, to better understand\nthe mechanism of frustration between the smectic layer order and chirality. As\nthe chirality increases, the effective bending rigidity of layers is reduced\ndue to unlocking of the layer orientation and the director. This results in\nlarge deviation of the layer morphology from that of Scherk's first minimal\nsurface and linear stack of screw dislocations (LSD).",
        "positive": "The Intriguing Flow Behavior of Soft Materials: Materials that can be deformed by thermal stresses at room temperature are\ncalled soft materials. Colloidal suspensions comprising solid particles evenly\ndistributed in a fluid phase (smoke, fog, ink and milk, for example),\nemulsions(mayonnaise, lotions and creams), pastes (tomato ketchup, toothpaste),\ngranular media (a bag of rice or sand), and polymer gels (polysaccharide gels)\ncan be categorized as soft materials and are ubiquitous both at home and in\nindustrial setups. Soft materials exhibit rich flow and deformation behaviors\ncharacterized by intriguing properties such as shear-thinning or thixotropy,\nshear-thickening or dilatancy, non-zero normal and yield stresses, etc. This\narticle explains some of the mysterious flow properties of soft materials."
    },
    {
        "anchor": "Theory of Coherent Van der Waals Matter: We explain in depth the previously proposed theory of the coherent Van der\nWaals(cVdW) interaction - the counterpart of Van der Waals (VdW) force -\nemerging in spatially coherently fluctuating electromagnetic fields. We show\nthat cVdW driven matter is dominated by many body interactions, which are\nsignificantly stronger than those found in standard Van der Waals (VdW)\nsystems. Remarkably, the leading 2- and 3-body interactions are of the same\norder with respect to the distance $(\\propto R^{-6})$, in contrast to the\nusually weak VdW 3-body effects ($\\propto R^{-9}$). From a microscopic theory\nwe show that the anisotropic cVdW many body interactions drive the formation of\nlow-dimensional structures such as chains, membranes and vesicles with very\nunusual, non-local properties. In particular, cVdW chains display a\nlogarithmically growing stiffness with the chain length, while cVdW membranes\nhave a bending modulus growing linearly with their size. We argue that the cVdW\nanisotropic many body forces cause local cohesion but also a negative effective\n\"surface tension\". We conclude by deriving the equation of state for cVdW\nmaterials and propose new experiments to test the theory, in particular the\nunusual 3-body nature of cVdW.",
        "positive": "Dynamics of lysozyme and its hydration water under electric field: The effects of static electric field on the dynamics of lysozyme and its\nhydration water have been investigated by means of incoherent quasi-elastic\nneutron scattering (QENS). Measurements were performed on lysozyme samples,\nhydrated respectively with heavy water (D2O) to capture the protein dynamics,\nand with light water (H2O), to probe the dynamics of the hydration shell, in\nthe temperature range from 210 $<$ T $<$ 260 K. The hydration fraction in both\ncases was about $\\sim$ 0.38 gram of water per gram of dry protein. The field\nstrengths investigated were respectively 0 kV/mm and 2 kV/mm (2 10$^6$ V/m) for\nthe protein hydrated with D2O and 0 kV and 1 kV/mm for the H2O hydrated\ncounterpart. While the overall internal protons dynamics of the protein appears\nto be unaffected by the application of electric field up to 2 kV/mm, likely due\nto the stronger intra-molecular interactions, there is also no appreciable\nquantitative enhancement of the diffusive dynamics of the hydration water, as\nwould be anticipated based on our recent observations in water confined in\nsilica pores under field values of 2.5 kV/mm. This may be due to the difference\nin surface interactions between water and the two adsorption hosts (silica and\nprotein), or to the existence of a critical threshold field value Ec $\\sim$ 2-3\nkV/mm for increased molecular diffusion, for which electrical breakdown is a\nlimitation for our sample."
    },
    {
        "anchor": "Modelling the ion-exchange equilibrium in nanoporous materials: Distribution of a two component electrolyte mixture between the model\nadsorbent and a bulk aqueous electrolyte solution was studied using the replica\nOrnstein-Zernike theory and the grand canonical Monte Carlo method. The\nelectrolyte components were modelled to mimic the HCl/NaCl and HCl/CaCl_2\nmixtures, respectively. The matrix, invaded by the primitive model electrolyte\nmixture, was formed from monovalent negatively charged spherical obstacles. The\nsolution was treated as a continuous dielectric with the properties of pure\nwater. Comparison of the pair distribution functions (obtained by the two\nmethods) between the various ionic species indicated a good agreement between\nthe replica Ornstein-Zernike results and machine calculations. Among\nthermodynamic properties, the mean activity coefficient of the invaded\nelectrolyte components was calculated. Simple model for the ion-exchange resin\nwas proposed. The selectivity calculations yielded qualitative agreement with\nthe following experimental observations: (i) selectivity increases with the\nincreasing capacity of the adsorbent (matrix concentration), (ii) the adsorbent\nis more selective for the ion having higher charge density if its fraction in\nmixture is smaller.",
        "positive": "DNA brick self-assembly with an off-lattice potential: We report Monte Carlo simulations of a simple off-lattice patchy-particle\nmodel for DNA `bricks'. We relate the parameters that characterise this model\nwith the binding free energy of pairs of single-stranded DNA molecules. We\nverify that an off-lattice potential parameterised in this way reproduces much\nof the behaviour seen with a simpler lattice model we introduced previously,\nalthough the relaxation of the geometric constraints leads to a more\nerror-prone self-assembly pathway. We investigate the self-assembly process as\na function of the strength of the non-specific interactions. We show that our\noff-lattice model for DNA bricks results in robust self-assembly into a variety\nof target structures."
    },
    {
        "anchor": "Thermodynamic perturbation theory for associating fluids with small bond\n  angles: Effects of steric hindrance, ring formation and double bonding: We develop the first comprehensive approach to model associating fluids with\nsmall bond angles using Wertheim's perturbation theory. We show theoretically\nand through monte carlo simulations that as bond angle is varied various modes\nof association become dominant. The new theory is shown to be in excellent\nagreement with monte carlo simulation for the prediction of the internal\nenergy, pressure and fractions in rings, chains, double bonded over the full\nrange of bond angles.",
        "positive": "Simple analysis of scattering data with Ornstein-Zernike equation: In this paper we propose and explore a method of analysis of the scattering\nexperimental data for uniform liquid-like systems. In our pragmatic approach we\nare not trying to introduce by hands an artificial small parameter to work out\na perturbation theory with respect to the known results e.g., for hard spheres\nor sticky-hard spheres (all the more that in the agreement with the notorious\nLandau statement, there is no any physical small parameter for liquids).\nInstead of it guided by the experimental data we are solving the the\nOrnstein-Zernike equation with a trial (variational) form of the inter-particle\ninteraction potential. To find all needed correlation functions this\nvariational input is iterated numerically to satisfy the Ornstein-Zernike\nequation supplemented by a closure relation. We illustrate by a number of model\nand real experimental examples of the X-ray and neutron scattering data how the\napproach works."
    },
    {
        "anchor": "Generalized Finsler geometry and the anisotropic tearing of skin: A continuum mechanical theory with foundations in generalized Finsler\ngeometry describes the complex anisotropic behavior of skin. A fiber bundle\napproach, encompassing total spaces with assigned linear and nonlinear\nconnections, geometrically characterizes evolving configurations of a\ndeformable body with microstructure. An internal state vector is introduced on\neach configuration, describing subscale physics. A generalized Finsler metric\ndepends on position and the state vector, where the latter dependence allows\nfor both direction (i.e., as in Finsler geometry) as well as magnitude.\nEquilibrium equations are derived using a variational method, extending\nconcepts of finite-strain hyperelasticity coupled to phase-field mechanics to\ngeneralized Finsler space. For application to skin tearing, state vector\ncomponents represent microscopic damage processes (e.g., fiber rearrangements\nand ruptures) in different directions with respect to intrinsic orientations\n(e.g., parallel or perpendicular to Langer's lines). Nonlinear potentials,\nmotivated from soft-tissue mechanics and phase-field fracture theories, are\nassigned with orthotropic material symmetry pertinent to properties of skin.\nGoverning equations are derived for one- and two-dimensional base manifolds.\nAnalytical solutions capture experimental force-stretch data, toughness, and\nobservations on evolving microstructure, in a more geometrically and physically\ndescriptive way than prior phenomenological models.",
        "positive": "State-dependent stiffness enhances wave propagation along elastic\n  filaments: We study an elastic filament beating in a viscous fluid with\ncurvature-dependent bending stiffness. Our numerical and experimental\ninvestigations reveal that such differential stiffness can sustain planar\nbending waves far along flexible filaments. In particular, basal actuation is a\nviable, parsimonious mechanism for generating high-amplitude planar bending\nwaves, in stark contrast to the uniform-stiffness case. Further, the resulting\nbeat patterns closely resemble the power-and-recovery strokes of propulsive\nbiological filaments, suggesting applications in robotic and engineered\nsystems."
    },
    {
        "anchor": "A generalized conservation law for main-chain polymer nematics: We explore the implications of the conservation law(s) and the corresponding\n\"continuity equation(s)\", resulting from the coupling between the positional\nand the orientational order in main-chain polymer nematics, by showing that the\nvectorial and tensorial forms of these equations are in general not equivalent\nand can not be reduced to one another, but neither are they disjoint\nalternatives. We analyze the relation between them and elucidate the\nfundamental role that the chain backfolding plays in the determination of their\nrelative strength and importance. Finally, we show that the correct penalty\npotential in the effective free energy, implementing these conservation laws,\nshould actually connect both the tensorial and the vectorial constraints. We\nshow that the consequences of the polymer chains connectivity for their\nconsistent mesoscopic description are thus not only highly non-trivial but that\nits proper implementation is absolutely crucial for a consistent coarse grained\ndescription of the main-chain polymer nematics.",
        "positive": "Volume Effects on the Glass Transition Dynamics: The role of jamming (steric constraints) and its relationship to the\navailable volume is addressed by examining the effect that certain\nmodifications of a glass-former have on the ratio of its isochoric and isobaric\nactivation enthalpies. This ratio reflects the relative contribution of volume\n(density) and temperature (thermal energy) to the temperature-dependence of the\nrelaxation times of liquids and polymers. We find that an increase in the\navailable volume confers a stronger volume-dependence to the relaxation\ndynamics, a result at odds with free volume interpretations of the glass\ntransition."
    },
    {
        "anchor": "Demonstration of variable angle Super-Heterodyne Dynamic Light\n  Scattering for measuring colloidal dynamics: We demonstrate a prototype light scattering instrument combining a frequency\ndomain approach to the intermediate scattering function from Super-Heterodyning\nDoppler Velocimetry with the versatility of a standard homodyne Dynamic Light\nScattering goniometer setup for investigations over a large range of scattering\nvectors. Comparing to reference experiments in correlation-time domain, we show\nthat the novel approach can determine diffusion constants and hence\nhydrodynamic radii with high precision and accuracy. Possible future\napplications are discussed shortly.",
        "positive": "Obstruction enhances the diffusivity of self-propelled rod-like\n  particles: Diffusion of self-propelled particles in the presence of randomly distributed\nobstacles in three dimensions is studied using molecular dynamics simulations.\nIt is found that depending on the magnitude of the propelling force and the\nparticle aspect ratio, the diffusion coefficient can be a monotonically\ndecreasing or a non-monotonic concave function of the obstructed volume\nfraction. Counterintuitive enhancement of the particle diffusivity with\nincreasing the obstacles crowd is shown to be a combinatory effect of the\nself-propelling force and the anisotropy in the shape of the particle. Regions\ncorresponding to monotonic and non-monotonic dependence of the particle\ndiffusivity on the obstacle density in propelling force-aspect ratio plane are\nspecified theoretically and using the simulation results."
    },
    {
        "anchor": "Thermodynamic stability of fluid-fluid phase separation in binary\n  athermal mixtures: The role of nonadditivity: We study the thermodynamic stability of fluid-fluid phase separation in\nbinary nonadditive mixtures of hard-spheres for moderate size ratios. We are\ninterested in elucidating the role played by small amounts of nonadditivity in\ndetermining the stability of fluid-fluid phase separation with respect to the\nfluid-solid phase transition. The demixing curves are built in the framework of\nthe modified-hypernetted chain and of the Rogers-Young integral equation\ntheories through the calculation of the Gibbs free energy. We also evaluate\nfluid-fluid phase equilibria within a first-order thermodynamic perturbation\ntheory applied to an effective one-component potential obtained by integrating\nout the degrees of freedom of the small spheres. A qualitative agreement\nemerges between the two different approaches. We also address the determination\nof the freezing line by applying the first-order thermodynamic perturbation\ntheory to the effective interaction between large spheres. Our results suggest\nthat for intermediate size ratios a modest amount of nonadditivity, smaller\nthan earlier thought, can be sufficient to drive the fluid-fluid critical point\ninto the thermodinamically stable region of the phase diagram. These findings\ncould be significant for rare-gas mixtures in extreme pressure and temperature\nconditions, where nonadditivity is expected to be rather small.",
        "positive": "Propagating compaction bands in confined compression of snow: Experiment\n  and Modelling: We show that the plastic deformation of snow under uniaxial compression is\ncharacterized by complex spatio-temporal strain localization phenomena.\nDeformation is characterized by repeated nucleation and propagation of\ncompaction bands. Compaction bands are also observed during the very first\nstage of compression of solid foams where a single band moves across the sample\nat approximately constant stress. However, snow differs from these materials as\nrepeated nucleation and propagation of bands occurs throughout the subsequent\nhardening stage until the end of the deformation experiment. Band nucleation\nand/or reflection of bands at the sample boundaries are accompanied by stress\ndrops which punctuate the stress strain curve. A constitutive model is proposed\nwhich quantitatively reproduces all features of this oscillatory deformation\nmode. To this end, a well-established compressive plasticity framework for\nsolid foams is generalized to account for shear softening behavior, time\ndependence of microstructure (`rapid sintering') and non-locality of damage\nprocesses in snow."
    },
    {
        "anchor": "Designing slower glasses by manipulating their local structure: Glasses remain an elusive and poorly understood state of matter. For example,\nit is not clear how we can design an efficient macroscopic glass former by\ntuning the properties of its microscopic building blocks. In this paper, we\npropose a simple directional colloidal model that reinforces the optimal\nicosahedral local structure of binary hard-sphere glasses. We show that only\nthis specific symmetry results in a dramatic slowing down of the dynamics. Our\nresults open the door to controlling the dynamics of dense glassy systems by\nselectively promoting specific local structural environments.",
        "positive": "Note on \"Hydrodynamic Phase Locking of Swimming Microorganisms\": We make remarks on Elfring and Lauga's [{\\it Phys. Rev. Lett.} {\\bf 103},\n088101 (2009)] paper. The energy dissipation or viscous dissipation plays an\nimportant role in the phase-locked state."
    },
    {
        "anchor": "Coarsening of Two Dimensional Foam on a Dome: In this paper we report on bubble growth rates and on the statistics of\nbubble topology for the coarsening of a dry foam contained in the narrow gap\nbetween two hemispheres. By contrast with coarsening in flat space, where\nsix-sided bubbles neither grow nor shrink, we observe that six sided bubbles\ngrow with time at a rate that depends on their size. This result agrees with\nthe modification to von Neumann's law predicted by J.E. Avron and D. Levine.\nFor bubbles with a different number of sides, except possibly seven, there is\ntoo much noise in the growth rate data to demonstrate a difference with\ncoarsening in flat space. In terms of the statistics of bubble topology, we\nfind fewer 3, 4, and 5 sided bubbles, and more 6 and greater sided bubbles, in\ncomparison with the stationary distribution for coarsening in flat space. We\nalso find good general agreement with the Aboav-Weaire law for the average\nnumber of sides of the neighbors of an n-sided bubble.",
        "positive": "A fast and efficient deep learning procedure for tracking droplet motion\n  in dense microfluidic emulsions: We present a deep learning-based object detection and object tracking\nalgorithm to study droplet motion in dense microfluidic emulsions. The deep\nlearning procedure is shown to correctly predict the droplets' shape and track\ntheir motion at competitive rates as compared to standard clustering\nalgorithms, even in the presence of significant deformations. The deep learning\ntechnique and tool developed in this work could be used for the general study\nof the dynamics of biological agents in fluid systems, such as moving cells and\nself-propelled micro organisms in complex biological flows."
    },
    {
        "anchor": "Using Acoustic Perturbations to Dynamically Tune Shear Thickening in\n  Colloidal Suspensions: Colloidal suspensions in industrial processes often exhibit shear thickening\nthat is difficult to control actively. Here, we use piezoelectric transducers\nto apply acoustic perturbations to dynamically tune the suspension viscosity in\nthe shear-thickening regime. We attribute the mechanism of dethickening to the\ndisruption of shear-induced force chains via perturbations that are large\nrelative to the particle roughness scale. The ease with which this technique\ncan be adapted to various flow geometries makes it a powerful tool for actively\ncontrolling suspension flow properties and investigating system dynamics.",
        "positive": "On the Ohm law in dilute colloidal polyelectrolytes: We discuss the peculiarities of the Ohm law in dilute polyelectrolytes\ncontaining a relatively low concentration of the multiply-charged colloidal\nparticles. It is demonstrated that in this conditions, the effective\nconductivity of polyelectrolyte is the linear function of colloidal particles\nconcentration. This happens due to the change of electric field in the\npolyelectrolyte under the effect of colloidal particle polarization.\n  Such mechanism gives grounds to propose the alternative scenario for the\nphenomenon observed experimentally."
    },
    {
        "anchor": "Orientational dynamics and rheology of active suspensions in weakly\n  viscoelastic flows: Microswimmer suspensions in Newtonian fluids exhibit unusual macroscale\nproperties, such as a superfluidic behavior, which can be harnessed to perform\nwork at microscopic scales. Since most biological fluids are non-Newtonian,\nhere we study the rheology of a microswimmer suspension in a weakly\nviscoelastic shear flow. At the individual level, we find that the viscoelastic\nstresses generated by activity substantially modify the Jeffery orbits\nwell-known from Newtonian fluids. The orientational dynamics depends on the\nswimmer type; especially pushers can resist flow-induced rotation and align at\nan angle with the flow. To analyze its impact on bulk rheology, we study a\ndilute microswimmer suspension in the presence of random tumbling and\nrotational diffusion. Strikingly, swimmer activity and its elastic response in\npolymeric fluids alter the orientational distribution and substantially amplify\nthe swimmer-induced viscosity. This suggests that pusher suspensions reach the\nsuperfluidic regime at lower volume fractions compared to a Newtonian fluid\nwith identical viscosity.",
        "positive": "Statistics of microscopic yielding in sheared aqueous foams: We detail the statistical distribution of bubble rearrangements in a sheared\ntwo-dimensional foam. Such rearrangements, known as T1 events, are vital to\nmechanisms resulting in flow through microscopic mechanical yielding. We find\nthat at a constant rate of shear, the rate of occurrence of T1 events shows\nonly small fluctuations. This rate is however seen to vary significantly with a\nvariation in the initial configuration of bubbles constituting the foam. In\naddition, we detail the spatial and orientational distribution of T1 events and\nrelate them to the distribution of stresses in the bulk of the material. Some\ninsights into the irreversibility of the dynamics are also discussed."
    },
    {
        "anchor": "How to Define Variation of Physical Properties Normal to an Undulating\n  One-Dimensional Object: One-dimensional flexible objects are abundant in physics, from polymers to\nvortex lines to defect lines and many more. These objects structure their\nenvironment and it is natural to assume that the influence these objects exert\non their environment depends on the distance from the line-object. But how\nshould this be defined? We argue here that there is an intrinsic length scale\nalong the undulating line that is a measure of its \"stiffness\" (i.e.,\norientational persistence), which yields a natural way of defining the\nvariation of physical properties normal to the undulating line. We exemplify\nhow this normal variation can be determined from a computer simulation for the\ncase of a so-called bottle-brush polymer, where side chains are grafted onto a\nflexible backbone.",
        "positive": "Characterizing the mesh size of polymer solutions via the pore size\n  distribution: In order to characterize the geometrical mesh size $\\xi$, we simulate a\nsolution of coarse-grained polymers with densities ranging from the dilute to\nthe concentrated regime and for different chain lengths. Conventional ways to\nestimate $\\xi$ rely either on scaling assumptions which give $\\xi$ only up to\nan unknown multiplicative factor, or on measurements of the monomer density\nfluctuation correlation length $\\xi_c$. We determine $\\xi_c$ from the monomer\nstructure factor and from the radial distribution function, and find that the\nidentification $\\xi=\\xi_c$ is not justified outside of the semidilute regime.\nIn order to better characterize $\\xi$, we compute the pore size distribution\n(PSD) following two different definitions, one by Torquato et al. (Ref.1) and\none by Gubbins et al. (Ref.2). We show that the mean values of the two\ndistributions, $\\langle r \\rangle_T$ and $\\langle r \\rangle_G$, both display\nthe behavior predicted for $\\xi$ by scaling theory, and argue that $\\xi$ can be\nidentified with either one of these quantities. This identification allows to\ninterpret the PSD as the distribution of mesh sizes, a quantity which\nconventional methods cannot access. Finally, we show that it is possible to map\na polymer solution on a system of hard or overlapping spheres, for which\nTorquato's PSD can be computed analytically and reproduces accurately the PSD\nof the solution. We give an expression that allows $\\langle r \\rangle_T$ to be\nestimated with great accuracy in the semidilute regime by knowing only the\nradius of gyration and the density of the polymers."
    },
    {
        "anchor": "Acoustic propulsion of nano- and microcones: dependence on the viscosity\n  of the surrounding fluid: This article investigates how the acoustic propulsion of cone-shaped\ncolloidal particles that are exposed to a traveling ultrasound wave depends on\nthe viscosity of the fluid surrounding the particles. Using acoustofluidic\ncomputer simulations, we found that the propulsion of such nano- and microcones\ndecreases strongly and even changes sign for increasing shear viscosity. In\ncontrast, we found only a weak dependence of the propulsion on the bulk\nviscosity. The obtained results are in line with the findings of previous\ntheoretical and experimental studies.",
        "positive": "Origami Multistabilty: From Single Vertices to Metasheets: We explore the surprisingly rich energy landscape of origami-like folding\nplanar structures. We show that the configuration space of rigid-paneled\ndegree-4 vertices, the simplest building blocks of such systems, consists of at\nleast two distinct branches meeting at the flat state. This suggests that\ngeneric vertices are at least bistable, but we find that the nonlinear nature\nof these branches allows for vertices with as many as five distinct stable\nstates. In vertices with collinear folds and/or symmetry, more branches emerge\nleading to up to six stable states. Finally, we introduce a procedure to tile\narbitrary 4-vertices while preserving their stable states, thus allowing the\ndesign and creation of multistable origami metasheets."
    },
    {
        "anchor": "Pulsed vacuum arc deposition of nitrogen-doped diamond-like coatings for\n  long-term hydrophilicity of electrospun polycaprolactone scaffolds: The surface hydrophobicity of poly($\\epsilon$-caprolactone) electrospun\nscaffolds prevents their interactions with cells and tissue integration. Plasma\ntreatment of the scaffolds enhances their hydrophilicity. However, the\nhydrophobicity of scaffolds is restored in about 30 days. In this\ncommunication, we report the possibility of polycaprolactone electrospun\nscaffolds hydrophilization for more than 6 months. For that, diamond-like\ncoating was deposited on the scaffolds surface using pulsed vacuum arc\ndeposition technique in nitrogen atmosphere with sputtering of graphite target.\nIt was established that single-side modification preserving scaffold structure\nis possible. The diamond-like coatings composition (sp2/sp3 hybridized carbon\nratio) was tunable with nitrogen pressure. In vitro tests with fibroblasts cell\nculture did not reveal any cytotoxic compounds in the samples extracts.",
        "positive": "Re-entrant bimodality in spheroidal chiral swimmers in shear flow: We use a continuum model to report on the behavior of a dilute suspension of\nchiral swimmers subject to externally imposed shear in a planar channel.\nSwimmer orientation in response to the imposed shear can be characterized by\ntwo distinct phases of behavior, corresponding to unimodal or bimodal\ndistribution functions for swimmer orientation along the channel. These phases\nindicate the occurrence (or not) of a population splitting phenomenon changing\nthe swimming direction of a macroscopic fraction of active particles to the\nexact opposite of that dictated by the imposed flow. We present a detailed\nquantitative analysis elucidating the complexities added to the population\nsplitting behavior of swimmers when they are chiral. In particular, the\ntransition from unimodal to bimodal and vice versa are shown to display a\nre-entrant behavior across the parameter space spanned by varying the chiral\nangular speed. We also present the notable effects of particle aspect ratio and\nself-propulsion speed on system phase behavior and discuss potential\nimplications of our results in applications such as swimmer separation/sorting."
    },
    {
        "anchor": "Two dimension porous media reconstruction using granular model under\n  influence of gravity: Modeling of pores generation in 2-D with granular grains using molecular\ndynamics method is reported in this work. Grains with certain diameter\ndistribution are let falling due to gravity. Three configurations (larger\ndiameter on top, smaller diameter on top, and mixed) and two kinds of mixture\n(same grains density and same grains mass) are used in the simulation. Mixture\nwith heterogen density gives higher porosity than the homogen one for higher\ninitial height, but change into opposite condition for lower initial height.",
        "positive": "Polymer Welding: Strength Through Entanglements: Large-scale simulations of thermal welding of polymers are performed to\ninvestigate the rise of mechanical strength at the polymer-polymer interface\nwith the welding time. The welding process is in the core of integrating\npolymeric elements into devices as well as in thermal induced healing of\npolymers; processes that require development of interfacial strength equal to\nthat of the bulk. Our simulations show that the interfacial strength saturates\nat the bulk shear strength much before polymers diffuse by their radius of\ngyration. Along with the strength increase, the dominant failure mode changes\nfrom chain pullout at the interface to chain scission as in the bulk. Formation\nof sufficient entanglements across the interface, which we track using a\nPrimitive Path Analysis is required to arrest catastrophic chain pullout at the\ninterface. The bulk response is not fully recovered until the density of\nentanglements at the interface reaches the bulk value. Moreover, the increase\nof interfacial strength before saturation is proportional to the number of\ninterfacial entanglements between chains from opposite sides."
    },
    {
        "anchor": "Effects of co-ordination number on the nucleation behaviour in\n  many-component self-assembly: We report canonical and grand-canonical lattice Monte Carlo simulations of\nthe self-assembly of addressable structures comprising hundreds of distinct\ncomponent types. The nucleation behaviour, in the form of free-energy barriers\nto nucleation, changes significantly as the co-ordination number of the\nbuilding blocks is changed from 4 to 8 to 12. Unlike tetrahedral structures -\nwhich roughly correspond to DNA bricks that have been studied in experiment -\nthe shapes of the free-energy barriers of higher co-ordination structures\ndepend strongly on the supersaturation, and such structures require a very\nsignificant driving force for structure growth before nucleation becomes\nthermally accessible. Although growth at high supersaturation results in more\ndefects during self-assembly, we show that high co-ordination number structures\ncan still be assembled successfully in computer simulations and that they\nexhibit self-assembly behaviour analogous to DNA bricks. In particular, the\nself-assembly remains modular, enabling in principle a wide variety of\nnanostructures to be assembled, with a greater spatial resolution than is\npossible in low co-ordination structures.",
        "positive": "Optimal active particle navigation meets machine learning: The question of how \"smart\" active agents, like insects, microorganisms, or\nfuture colloidal robots need to steer to optimally reach or discover a target,\nsuch as an odor source, food, or a cancer cell in a complex environment has\nrecently attracted great interest. Here, we provide an overview of recent\ndevelopments, regarding such optimal navigation problems, from the micro- to\nthe macroscale, and give a perspective by discussing some of the challenges\nwhich are ahead of us. Besides exemplifying an elementary approach to optimal\nnavigation problems, the article focuses on works utilizing machine\nlearning-based methods. Such learning-based approaches can uncover highly\nefficient navigation strategies even for problems that involve e.g. chaotic,\nhigh-dimensional, or unknown environments and are hardly solvable based on\nconventional analytical or simulation methods."
    },
    {
        "anchor": "Humidity-induced glass transition of a polyelectrolyte brush creates\n  switchable friction in air: Polymer brushes have found extensive applications as responsive surfaces,\nparticularly in achieving tunable friction in solvent environments. Despite\nrecent interest in extending this technology to air environments, little is\nknown about the impact of vapor absorption on friction. Considering\npolyelectrolyte brushes, we report findings that reveal, with increasing\nrelative humidity, a trend of frictional shear forces decaying over two orders\nof magnitude only after achieving a critical humidity. However, water\nabsorption, structure, and swelling of the brushes followed continuous trends\nwith increasing humidity. In contrast, a humidity-induced glass transition\noccurred which caused a shift from dry to fluid-like sliding with the\nwater-swollen brush acting as the lubricant. Below the glass transition,\nfriction is large without regard to water concentration; thus, friction\ntransitions sharply. This switching mechanism, shown to be a general property\nof the hygroscopic polymer, provides new opportunities for switchable friction\nor other surface actuation from vapor stimuli.",
        "positive": "Cluster Monte Carlo and numerical mean field analysis for the water\n  liquid--liquid phase transition: By the Wolff's cluster Monte Carlo simulations and numerical minimization\nwithin a mean field approach, we study the low temperature phase diagram of\nwater, adopting a cell model that reproduces the known properties of water in\nits fluid phases. Both methods allows us to study the water thermodynamic\nbehavior at temperatures where other numerical approaches --both Monte Carlo\nand molecular dynamics-- are seriously hampered by the large increase of the\ncorrelation times. The cluster algorithm also allows us to emphasize that the\nliquid--liquid phase transition corresponds to the percolation transition of\ntetrahedrally ordered water molecules."
    },
    {
        "anchor": "Palmitic Acid Sophorolipid Biosurfactant: From Self-Assembled Fibrillar\n  Network (SAFiN) To Hydrogels with Fast Recovery: Nanofibers are an interesting phase into which amphiphilic molecules can\nself-assemble. Described for a large number of synthetic lipids, they were\nseldom reported for natural lipids like microbial amphiphiles, known as\nbiosurfactants. In this work, we show that the palmitic acid congener of\nsophorolipids (SLC16:0), one of the most studied families of biosurfactants,\nspontaneously forms a self-assembled fiber network (SAFiN) at pH below 6\nthrough a pH jump process. pH-resolved in-situ Small Angle X-ray Scattering\n(SAXS) shows a continuous micelle-to-fiber transition, characterized by an\nenhanced core-shell contrast between pH 9 and pH 7 and micellar fusion into\nflat membrane between pH 7 and pH 6, approximately. Below pH 6, homogeneous,\ninfinitely long nanofibers form by peeling off the membranes. Eventually, the\nnanofiber network spontaneously forms a thixotropic hydrogel with fast recovery\nrates after applying an oscillatory strain amplitude out of the linear\nviscoelastic regime (LVER): after being submitted to strain amplitudes during 5\nmin, the hydrogel recovers about 80% and 100% of its initial elastic modulus\nafter, respectively, 20 s and 10 min. Finally, the strength of the hydrogel\ndepends on the medium's final pH, with an elastic modulus fivefold higher at pH\n3 than at pH 6.",
        "positive": "Self-generation of colligative properties at hydrophilic surfaces: The generally accepted view of osmotic pressure is that it is a colligative\nproperty, along with freezing point depression, boiling point elevation and\nvapour pressure lowering. These properties ideally depend on the concentration\nof dissolved solute molecules. Osmotic pressure, however, is also generated,\nwithout any solute, at hydrophilic surfaces. Here is presented a rationale and\nexplanation for this phenomenon."
    },
    {
        "anchor": "Phase separation and vortex states in binary mixture of Bose-Einstein\n  condensates in the trapping potentials with displaced centers: The system of two simultaneously trapped codensates consisting of $^{87}Rb$\natoms in two different hyperfine states is investigated theoretically in the\ncase when the minima of the trapping potentials are displaced with respect to\neach other. It is shown that the small shift of the minima of the trapping\npotentials leads to the considerable displacement of the centers of mass of the\ncondensates, in agreement with the experiment. It is also shown that the\ncritical angular velocities of the vortex states of the system drastically\ndepend on the shift and the relative number of particles in the condensates,\nand there is a possibility to exchange the vortex states between condensates by\nshifting the centers of the trapping potentials.",
        "positive": "Tunable liquid-liquid critical point in an ionic model of silica: Recently it was shown that the WAC model for liquid silica [L. V. Woodcock,\nC. A. Angell, and P. Cheeseman, J. Chem. Phys. 65, 1565 (1976)] is remarkably\nclose to having a liquid-liquid critical point (LLCP). We demonstrate that\nincreasing the ion charge separates the global maxima of the response\nfunctions, while reducing the charge smoothly merges them into a LLCP; a\nphenomenon that might be experimentally observable with charged colloids. An\nanalysis of the Si and O coordination numbers suggests that a sufficiently low\nSi/O coordination number ratio is needed to attain a LLCP."
    },
    {
        "anchor": "Ultra-delayed material failure via shear banding after straining an\n  amorphous material: We predict a phenomenon of catastrophic material failure arising suddenly\nwithin an amorphous material, with an extremely long delay time since the\nmaterial was last deformed. By simulating a mesoscopic soft glassy rheology\nmodel in one dimension (1D), a mesoscopic elastoplastic model in 1D and 2D, and\na continuum fluidity model in 1D, we demonstrate the basic physics to involve a\ndramatic ultra-delayed shear banding instability, in which strain suddenly\nstrongly localises within the material and the stress drops precipitously. The\ndelay time after the long historical shear strain was applied before failure\noccurs increases steeply with decreasing strain amplitude, decreasing working\ntemperature, and increasing sample annealing prior to shear. In demonstrating\nthe same physics -- which is directly testable experimentally and in particle\nsimulations -- to obtain within three different constitutive models, we suggest\nit may be generic across amorphous materials. The counter-intuitive prediction\nof catastrophic material failure long after any deformation was last applied\ncould have important consequences for material processing and performance.",
        "positive": "Nucleation kinetics in drying sodium nitrate aerosols: A quantitative understanding of the evaporative drying kinetics and\nnucleation rates of aqueous based aerosol droplets is important for a wide\nrange of applications, from atmospheric aerosols to industrial processes such\nas spray drying. Here, we introduce a numerical model for interpreting\nmeasurements of the evaporation rate and phase change of drying free droplets\nmade using a single particle approach. We explore the evaporation of aqueous\nsodium chloride and sodium nitrate solution droplets. Although the chloride\nsalt is observed to reproducibly crystallise at all drying rates, the nitrate\nsalt solution can lose virtually all of its water content without\ncrystallising. The latter phenomenon has implications for our understanding of\nthe competition between the drying rate and nucleation kinetics in these two\nsystems. The nucleation model is used in combination with the measurements of\ncrystallisation events to infer nucleation rates at varying equilibrium state\npoints, showing that classical nucleation theory provides a good description of\nthe crystallisation of the chloride salt but not the nitrate salt solution\ndroplets. The reasons for this difference are considered."
    },
    {
        "anchor": "Orientational ordering in a fluid of hard kites: A\n  density-functional-theory study: Using Density Functional Theory we theoretically study the orientational\nproperties of uniform phases of hard kites -- two isosceles triangles joined by\ntheir common base. Two approximations are used: Scaled Particle Theory, and a\nnew approach which better approximates third virial coefficients of\ntwo-dimensional hard particles. By varying some of their geometrical parameters\nkites can be transformed into squares, rhombuses, triangles, and also very\nelongated particles, even reaching the hard-needle limit. Thus a fluid of hard\nkites, depending on the particle shape, can stabilize isotropic, nematic,\ntetratic and triatic phases. Different phase diagrams are calculated, including\nthose of rhombuses, and kites with two of their equal interior angles fixed to\n$90^{\\circ}$, $60^{\\circ}$ and $75^{\\circ}$. Kites with one of their unequal\nangles fixed to $72^{\\circ}$, which have been recently studied via Monte Carlo\nsimulations, are also considered. We find that rhombuses and kites with two\nequal right angles and not too large anisometry stabilise the tetratic phase\nbut the latter stabilize it to a much higher degree. By contrast, kites with\ntwo equal interior angles fixed to $60^{\\circ}$ stabilize the triatic phase to\nsome extent, although it is very sensitive to changes in particle geometry.\nKites with the two equal interior angles fixed to $75^{\\circ}$ have a phase\ndiagram with both tetratic and triatic phases, but we show the nonexistence of\na particle shape for which both phases are stable at different densities.\nFinally the success of the new theory in the description of orientational order\nin kites is shown by comparing with Monte Carlo simulations for the case where\none of the unequal angles is fixed to $72^{\\circ}$. These particles also\npresent phase diagrams with stable tetratic and triatic phases.",
        "positive": "Extended Capillary Waves and the Negative Rigidity Coefficient in the\n  d=2 SOS model: The solid-on-solid (SOS) model of an interface separating two phases is\nexactly soluble in two dimensions (d=2) when the interface becomes a\none-dimensional string. The exact solution in terms of the transfer matrix is\nrecalled and the density-density correlation function $H(z_1,z_2;\\Delta x)$\ntogether with its projections, is computed. It is demonstrated that the shape\nfluctuations follow the (extended) capillary-wave theory expression\n$S(q)=kT/(D+\\gamma q^2 +\\kappa q^4) $ for sufficiently small wave vectors $q$.\nWe find $\\kappa$ {\\it negative}, $\\kappa <0$ . At $q=2\\pi$ there is a strong\nnearest-neighbor peak. Both these results confirm the earlier findings as\nestablished in simulations in d=3 and in continuous space, but now in an\nexactly soluble lattice model."
    },
    {
        "anchor": "Inter-particle adhesion induced strong mechanical memory in a dense\n  granular suspension: Repeated/cyclic shearing can drive amorphous solids to a steady-state\nencoding a memory of the applied strain amplitude. However, recent experiments\nfind that the effect of such memory formation on the mechanical properties of\nthe bulk material is rather weak. Here we study the memory effect in a yield\nstress solid formed by a dense suspension of cornstarch particles in paraffin\noil. Under cyclic shear, the system evolves towards a steady-state showing\ntraining-induced strain stiffening and plasticity. A readout reveals that the\nsystem encodes a strong memory of the training amplitude as indicated by a\nlarge change in the differential shear modulus. We observe that memory can be\nencoded for a wide range of training amplitude both above and below the\nyielding, albeit, the strength of the memory decreases with increasing the\ntraining amplitude. In-situ boundary imaging shows strain localization close to\nthe shearing boundaries, while the bulk of the sample moves like a solid plug.\nIn the steady-state, the average particle velocity (<v>) inside the solid-like\nregion slows down with respect to the moving plate as the strain approaches the\ntraining amplitude, however, as the readout strain crosses the amplitude, <v>\nsuddenly increases. We demonstrate that inter-particle adhesive interaction is\ncrucial for such a strong memory effect. Interestingly, our system can also\nremember more than one input only if the training strain with a smaller\namplitude is applied last.",
        "positive": "Electrostatic correlations on the ionic selectivity of cylindrical\n  membrane nanopores: We characterize the role of electrostatic fluctuations on the charge\nselectivity of cylindrical nanopores confining electrolyte mixtures. To this\nend, we develop an extended one-loop theory that can account for correlation\neffects induced by the surface charge, nanoconfinement of the electrolyte, and\ninterfacial polarization charges associated with the low permittivity membrane.\nWe validate the quantitative accuracy of the theory by comparisons with\npreviously obtained Monte-Carlo simulation data from the literature, and\nscrutinize in detail the underlying forces driving the ionic selectivity of the\nnanopore. In the biologically relevant case of electrolytes with divalent\ncations such as CaCl2 in negatively charged nanopores, electrostatic\ncorrelations associated with the dense counterion layer in the channel result\nin an increase of the pore coion density with the surface charge. This\npeculiarity analogous to the charge inversion phenomenon remains intact for\ndielectrically inhomogeneous pores, which indicates that the effect should be\nobservable in nanofiltration membranes or DNA-blocked nanopores characterized\nby a low membrane permittivity. Our results show that a quantitatively accurate\nconsideration of correlation effects is necessary to determine the ionic\nselectivity of nanopores in the presence of electrolytes with multivalent\ncounterions."
    },
    {
        "anchor": "Equilibrium properties and force-driven unfolding pathways of RNA\n  molecules: The mechanical unfolding of a simple RNA hairpin and of a 236--bases portion\nof the Tetrahymena thermophila ribozyme is studied by means of an Ising--like\nmodel. Phase diagrams and free energy landscapes are computed exactly and\nsuggest a simple two--state behaviour for the hairpin and the presence of\nintermediate states for the ribozyme. Nonequilibrium simulations give the\npossible unfolding pathways for the ribozyme, and the dominant pathway\ncorresponds to the experimentally observed one.",
        "positive": "Curvature in conformal mappings of 2D lattices and foam structure: The elegant properties of conformal mappings, when applied to two dimensional\n(2D) lattices, find interesting applications in 2D foams and other cellular or\nclose packed structures. In particular the 2D honeycomb (whose dual is the\ntriangular lattice) may be transformed into various conformal patterns, which\ncompare approximately to experimentally realisable 2D foams. We review and\nextend the mathematical analysis of such transformations, with several\nillustrative examples, and an account is given of the related work in energy\nminimisation problems. New results are adduced for the local curvature\ngenerated by the transformation."
    },
    {
        "anchor": "Capillary Waves in a Colloid-Polymer Interface: The structure and the statistical fluctuations of interfaces between\ncoexisting phases in the Asakura-Oosawa (AO) model for a colloid--polymer\nmixture are analyzed by extensive Monte Carlo simulations. We make use of a\nrecently developed grand canonical cluster move with an additional constraint\nstabilizing the existence of two interfaces in the (rectangular) box that is\nsimulated. Choosing very large systems, of size LxLxD with L=60 and D=120,\nmeasured in units of the colloid radius, the spectrum of capillary wave-type\ninterfacial excitations is analyzed in detail. The local position of the\ninterface is defined in terms of a (local) Gibbs surface concept. For small\nwavevectors capillary wave theory is verified quantitatively, while for larger\nwavevectors pronounced deviations show up. For wavevectors that correspond to\nthe typical distance between colloids in the colloid-rich phase, the\ninterfacial fluctuations exhibit the same structure as observed in the bulk\nstructure factor. When one analyzes the data in terms of the concept of a\nwavevector-dependent interfacial tension, a monotonous decrease of this\nquantity with increasing wavevector is found. Limitations of our analysis are\ncritically discussed.",
        "positive": "Dielectric relaxation of DNA aqueous solutions: We report on a detailed characterization of complex dielectric response of\nNa-DNA aqueous solutions by means of low-frequency dielectric spectroscopy (40\nHz - 110 MHz). Results reveal two broad relaxation modes of strength\n20<\\Delta\\epsilon_LF<100 and 5<\\Delta\\epsilon_HF<20, centered at 0.5\nkHz<\\nu_LF<70 kHz and 0.1 MHz<\\nu_HF<15 MHz. The characteristic length scale of\nthe LF process, 50<L_LF<750nm, scales with DNA concentration as\nc_DNA^{-0.29\\pm0.04} and is independent of the ionic strength in the low added\nsalt regime. Conversely, the measured length scale of the LF process does not\nvary with DNA concentration but depends on the ionic strength of the added salt\nas I_s^{-1} in the high added salt regime. On the other hand, the\ncharacteristic length scale of the HF process, 3<L_HF<50 nm, varyes with DNA\nconcentration as c_DNA^{-0.5} for intermediate and large DNA concentrations. At\nlow DNA concentrations and in the low added salt limit the characteristic\nlength scale of the HF process scales as c_DNA^{-0.33}. We put these results in\nperspective regarding the integrity of the double stranded form of DNA at low\nsalt conditions as well as regarding the role of different types of counterions\nin different regimes of dielectric dispersion. We argue that the free DNA\ncounterions are primarily active in the HF relaxation, while the condensed\ncounterions play a role only in the LF relaxation. We also suggest theoretical\ninterpretations for all these length scales in the whole regime of DNA and salt\nconcentrations and discuss their ramifications and limitations."
    },
    {
        "anchor": "The self-propelled Brownian spinning top: dynamics of a biaxial swimmer\n  at low Reynolds numbers: Recently, the Brownian dynamics of self-propelled (active) rod-like particles\nwas explored to model the motion of colloidal microswimmers,\ncatalytically-driven nanorods, and bacteria. Here, we generalize this\ndescription to biaxial particles with arbitrary shape and derive the\ncorresponding Langevin equation for a self-propelled Brownian spinning top. The\nbiaxial swimmer is exposed to a hydrodynamic Stokes friction force at low\nReynolds numbers, to fluctuating random forces and torques as well as to an\nexternal and an internal (effective) force and torque. The latter quantities\ncontrol its self-propulsion. Due to biaxiality and hydrodynamic\ntranslational-rotational coupling, the Langevin equation can only be solved\nnumerically. In the special case of an orthotropic particle in the absence of\nexternal forces and torques, the noise-free (zero-temperature) trajectory is\nanalytically found to be a circular helix. This trajectory is confirmed\nnumerically to be more complex in the general case involving a transient\nirregular motion before ending up in a simple periodic motion. By contrast, if\nthe external force vanishes, no transient regime is found and the particle\nmoves on a superhelical trajectory. For orthotropic particles, the\nnoise-averaged trajectory is a generalized concho-spiral. We furthermore study\nthe reduction of the model to two spatial dimensions and classify the\nnoise-free trajectories completely finding circles, straight lines with and\nwithout transients, as well as cycloids and arbitrary periodic trajectories.",
        "positive": "On the amplification of diffusion on piecewise linear potentails by\n  direct current: The diffusive motion of overdamped Brownian particles in tilted piecewise\nlinear pontentials is considered. It is shown that the enhancement of diffusion\ncoefficient by an external static force is quite sensitive to the symmetry of\nperiodic potential. Another new effect found is that the factor of randomness\nas a function of the tilting force exibits a plateau-like behaviour in the\nregion of low temperatures."
    },
    {
        "anchor": "Theory of Relaxation Dynamics in Glass-Forming Hydrogen-Bonded Liquids: We address the relaxation dynamics in hydrogen-bonded super-cooled liquids\nnear the glass transition, measured via Broad-Band Dielectric Spectroscopy\n(BDS). We propose a theory based on decomposing the relaxation of the\nmacroscopic dipole moment into contributions from hydrogen bonded clusters of\n$s$ molecules, with $s_{min}\\le s \\le s_{max}$. The existence of $s_{max}$ is\ndue to dynamical arrest and its value may depend on the cooling protocol and on\nthe aging time. The existence of $s_{max}$ is translated into a sum-rule on the\nconcentrations of clusters of size $s$. We construct the statistical mechanics\nof the super-cooled liquid subject to this sum-rule as a constraint, to\nestimate the temperature-dependent density of clusters of size $s$. With a\ntheoretical estimate of the relaxation time of each cluster we provide\npredictions for the real and imaginary part of the frequency dependent\ndielectric response. The predicted spectra and their temperature dependence are\nin accord with measurements, explaining a host of phenomenological fits like\nthe Vogel-Fulcher fit and the stretched exponential fit. Using glycerol as a\nparticular example we demonstrate quantitative correspondence between theory\nand experiments. The theory also demonstrates that the $\\alpha$ peak and the\n\"excess wing\" stem from the same physics in this material. The theory also\nshows that in other hydrogen -bonded glass formers the \"excess wing\" can\ndevelop into a $\\beta$ peak, depending on the molecular material parameters\n(predominantly the surface energy of the clusters). We thus argue that $\\alpha$\nand $\\beta$ peaks can stem from the same physics. Finally we address the BDS in\nconstrained geometries (pores) and explain why recent experiments on glycerol\ndid not show a deviation from bul k spectra.",
        "positive": "Lattice Boltzmann simulation of deformable fluid-filled bodies: progress\n  and perspectives: With the rapid development of studies involving droplet microfluidics, drug\ndelivery, cell detection, and microparticle synthesis, among others, many\nscientists have invested significant efforts to model the flow of these\nfluid-filled bodies. Motivated by the intricate coupling between hydrodynamics\nand the interactions of fluid-filled bodies, several methods have been\ndeveloped. The objective of this review is to present a compact foundation of\nthe methods used in the literature in the context of lattice Boltzmann methods.\nFor hydrodynamics, we focus on the lattice-Boltzmann method due to its specific\nability to treat time and spatial-dependent boundary conditions and to\nincorporate new physical models in a computationally efficient way. We split\nthe existing methods into two groups with regard to the interfacial boundary:\nfluid-structure and fluid-fluid methods. The fluid-structure methods are\ncharacterised by the coupling between fluid dynamics and mechanics of the\nflowing body, often used in applications involving membranes and similar\nflexible solid boundaries. We further divide fluid-structure-based methods into\ntwo subcategories, those which treat the fluid-structure boundary as a\ncontinuum medium and those that treat it as a discrete collection of individual\nsprings and particles. Next, we discuss the fluid-fluid methods, particularly\nuseful for the simulations of fluid-fluid interfaces. We focus on models for\nimmiscible droplets and their interaction in a suspending fluid and describe\nbenchmark tests to validate the models for fluid-filled bodies."
    },
    {
        "anchor": "Monte Carlo Simulation of Liquid-Crystal Alignment and of Chiral\n  Symmetry-Breaking: We carry out Monte Carlo simulations to investigate the effect of molecular\nshape on liquid-crystal order. In our approach, each model mesogen consists of\nseveral soft spheres bonded rigidly together. The arrangement of the spheres\nmay be straight (to represent uniaxial molecules), Z-shaped (for biaxial\nmolecules), or banana-shaped (for bent-core molecules). Using this approach, we\ninvestigate the alignment of the nematic phase by substrates decorated with\nparallel ridges. We compare results for wide and narrow ridge spacing and\nexamine local order near the substrates, and show that our results are\nconsistent with the predictions of Landau theory. We also investigate chiral\nsymmetry-breaking in systems of bent-core molecules. We find a chiral\ncrystalline phase as well as a nonchiral smectic-A phase, but not a chiral\nsmectic-C phase.",
        "positive": "Longitudinal dispersion of DNA in nanochannels: A theory is presented of the longitudinal dispersion of DNA under equilibrium\nconfined in a nanochannel. Orientational fluctuations of the DNA chain build up\nto give rise to substantial fluctuations of the coil in the longitudinal\ndirection of the channel. The translational and orientational degrees of\nfreedom of the polymer are described by the Green function satisfying the usual\nFokker-Planck equation. It is argued that this is analogous to the transport\nequation occurring in the theory of convective diffusion of particles in pipe\nflow. Moreover, Taylor's method may be used to reduce the Fokker-Planck\nequation to a diffusion equation for long DNA although subtleties arise\nconnected with the orientational distribution of segments within the channel.\nThe longitudinal \"step length\" turns out to be proportional to the typical\nangle of a DNA segment to the sixth power. The dispersion is underestimated\ncompared to experiment, probably because the harmonic approximation is used to\ndescribe the polymer confinement."
    },
    {
        "anchor": "Active matter in a viscoelastic environment: Active matter systems such as eukaryotic cells and bacteria continuously\ntransform chemical energy to motion. Hence living systems exert active stresses\non the complex environments in which they reside. One recurring aspect of this\ncomplexity is the viscoelasticity of the medium surrounding living systems:\nbacteria secrete their own viscoelastic extracellular matrix, and cells\nconstantly deform, proliferate, and self-propel within viscoelastic networks of\ncollagen. It is therefore imperative to understand how active matter modifies,\nand gets modified by, viscoelastic fluids. Here, we present a two-phase model\nof active nematic matter that dynamically interacts with a passive viscoelastic\npolymeric phase and perform numerical simulations in two dimensions to\nillustrate its applicability. Motivated by recent experiments we first study\nthe suppression of cell division by a viscoelastic medium surrounding the cell.\nWe further show that the self-propulsion of a model keratocyte cell is modified\nby the polymer relaxation of the surrounding viscoelastic fluid in a\nnon-uniform manner and find that increasing polymer viscosity effectively\nsuppresses the cell motility. Lastly, we explore the hampering impact of the\nviscoelastic medium on the generic hydrodynamic instabilities of active\nnematics by simulating the dynamics of an active stripe within a polymeric\nfluid. The model presented here can provide a framework for investigating more\ncomplex dynamics such as the interaction of multicellular growing systems with\nviscoelastic environments.",
        "positive": "Linear Exp6 Isotherm for Compressed Molten Cesium Over the Whole Liquid\n  range Including Metal-nonmetls Transition and Tc: The linear exp6 isotherm is presented as an approach to the thermodynamic\nproperies of liquid alkali metals over the whole liquid range including\nmetal-nonmetal transition. The exp6 pair interaction potential is applied to\napproach the underlying interplay between the characteristic soft repulsive\nintercation in dense, large attractive interaction in the expanded liquid\nalkali metal and the observed thermodynamic properties. PVT of dense liquid\nalkali metals obey the linear exp6 isotherm (Z-1)V2=A+Br-7/3\nexp{a(1-Cr-1/3/rm)} over the whole range of liquid densities, where Z is the\ncompression factor, r=1/V is the density, rm is the position of potential\nminimum, a is a parameter, and C is constant. The intercept A and the slope B\nsignificantly are related to attraction and repulsion, repectively, and both\ndepend on temperature. At the level of theory presented in this work, the\nthermodynamic effects caused by the polarization of atoms in expanded liquid\nalkali metals can be accounted for by exp6 potential function to demonestrat\ntheir thermodynamic properties as normal liquids. This incluids the\nmetal-nonmetal tarnsition in which case the nature of forces are changed in\nsuch a way that the thermodynamic properties would be different from those of\nthe high-density region. In particular the equation state for molten cesium is\nanalytical over the whole range of liquid densities. The linear exp6 isotherm\nis used to estimate the binding energy (0.0733 eV) and the position of\npotential minimum (0.5336 A) of liquid cesium st freezing temparature."
    },
    {
        "anchor": "Power law relationship between diffusion coefficients in multi-component\n  glass forming liquids: The slow down of dynamics in glass forming liquids as the glass transition is\napproached has been characterised through the Adam-Gibbs relation, which\nrelates relaxation time scales to the configurational entropy. The Adam-Gibbs\nrelation cannot apply simultaneously to all relaxation times scales unless they\nare coupled, and exhibit closely related temperature dependences. The breakdown\nof the Stokes-Einstein relation presents an interesting situation to the\ncontrary, and in analysing it, it has recently been shown that the Adam-Gibbs\nrelation applies to diffusion coefficients rather than to viscosity or\nstructural relaxation times related to the decay of density fluctuations.\nHowever, for multi-component liquids -- the typical cases considered in\ncomputer simulations, metallic glass formers, etc. -- such a statement raises\nthe question of which diffusion coefficient is described by the Adam-Gibbs\nrelation. All diffusion coefficients can be consistently described by the\nAdam-Gibbs relation if they bear a power law relationship with each other.\nRemarkably, we find that for a wide range of glass formers, and for a wide\nrange of temperatures spanning the normal and the slow relaxation regimes, such\na relationship holds. We briefly discuss possible rationalisations of the\nobserved behaviour.",
        "positive": "Memory-induced transition from a persistent random walk to circular\n  motion for achiral microswimmers: We experimentally study the motion of light-activated colloidal microswimmers\nin a viscoelastic fluid. We find that, in such a non-Newtonian environment, the\nactive colloids undergo an unexpected transition from enhanced angular\ndiffusion to persistent rotational motion above a critical propulsion speed,\ndespite their spherical shape and stiffness. We observe that, in contrast to\nchiral asymmetric microswimmers, the resulting circular orbits can\nspontaneously reverse their sense of rotation and exhibit an angular velocity\nand a radius of curvature that non-linearly depend on the propulsion speed. By\nmeans of a minimal non-Markovian Langevin model for active Brownian motion, we\nshow that these non-equilibrium effects emerge from the delayed response of the\nfluid with respect to the self-propulsion of the particle without counterpart\nin Newtonian fluids."
    },
    {
        "anchor": "Comment on \"Like-Charge Attraction and Hydrodynamic Interaction\": Comment on T. M. Squires and M. P. Brenner, Phys.Rev.Lett. 85, 4976 (2000)",
        "positive": "Kinetic Frustration Effects on Dense Two-Dimensional Packings of Convex\n  Particles and Their Structural Characteristics: The study of hard-particle packings is of fundamental importance in physics,\nchemistry, cell biology, and discrete geometry. Much of the previous work on\nhard-particle packings concerns their densest possible arrangements. By\ncontrast, we examine kinetic effects inevitably present in both numerical and\nexperimental packing protocols. Specifically, we determine how changing the\ncompression/shear rate of a two-dimensional packing of noncircular particles\ncauses it to deviate from its densest possible configuration, which is always\nperiodic. The adaptive shrinking cell (ASC) optimization scheme maximizes the\npacking fraction of a hard-particle packing by first applying random\ntranslations and rotations to the particles and then isotropically compressing\nand shearing the simulation box repeatedly until a possibly jammed state is\nreached. We use a stochastic implementation of the ASC optimization scheme to\nmimic different effective time scales by varying the number of particle moves\nbetween compressions/shears. We generate dense, effectively jammed,\nmonodisperse, two-dimensional packings of obtuse scalene triangle, rhombus,\ncurved triangle, lens, and \"ice cream cone\" (a semicircle grafted onto an\nisosceles triangle) shaped particles, with a wide range of packing fractions\nand degrees of order. To quantify these kinetic effects, we introduce the\nkinetic frustration index $K$, which measures the deviation of a packing from\nits maximum possible packing fraction. To investigate how kinetics affect\nshort- and long-range ordering in these packings, we compute their spectral\ndensities and characterize their contact networks. We find that kinetic effects\nare most significant when the particles have greater asphericity, less\ncurvature, and less rotational symmetry. This work may be relevant to the\ndesign of laboratory packing protocols."
    },
    {
        "anchor": "Competition for hydrogen bond formation in the helix-coil transition and\n  protein folding: The problem of the helix-coil transition of biopolymers in explicit solvents,\nlike water, with the ability for hydrogen bonding with solvent is addressed\nanalytically using a suitably modified version of the Generalized Model of\nPolypeptide Chains. Besides the regular helix-coil transition, an additional\ncoil-helix or reentrant transition is also found at lower temperatures. The\nreentrant transition arises due to competition between polymer-polymer and\npolymer-water hydrogen bonds. The balance between the two types of hydrogen\nbonding can be shifted to either direction through changes not only in\ntemperature, but also by pressure, mechanical force, osmotic stress or other\nexternal influences. Both polypeptides and polynucleotides are considered\nwithin a unified formalism. Our approach provides an explanation of the\nexperimental difficulty of observing the reentrant transition with pressure;\nand underscores the advantage of pulling experiments for studies of DNA.\nResults are discussed and compared with those reported in a number of recent\npublications with which a significant level of agreement is obtained.",
        "positive": "Emergence of macroscopic directed motion in populations of motile\n  colloids: From the formation of animal flocks to the emergence of coordinate motion in\nbacterial swarms, at all scales populations of motile organisms display\ncoherent collective motion. This consistent behavior strongly contrasts with\nthe difference in communication abilities between the individuals. Guided by\nthis universal feature, physicists have proposed that solely alignment rules at\nthe individual level could account for the emergence of unidirectional motion\nat the group level. This hypothesis has been supported by agent-based\nsimulations. However, more complex collective behaviors have been\nsystematically found in experiments including the formation of vortices,\nfluctuating swarms, clustering and swirling. All these model systems\npredominantly rely on actual collisions to display collective motion. As a\nresult, the potential local alignment rules are entangled with more complex,\noften unknown, interactions. The large-scale behavior of the populations\ntherefore depends on these uncontrolled microscopic couplings. Here, we\ndemonstrate a new phase of active matter. We reveal that dilute populations of\nmillions of colloidal rollers self-organize to achieve coherent motion along a\nunique direction, with very few density and velocity fluctuations. Identifying\nthe microscopic interactions between the rollers allows a theoretical\ndescription of this polar-liquid state. Comparison of the theory with\nexperiment suggests that hydrodynamic interactions promote the emergence of\ncollective motion either in the form of a single macroscopic flock at low\ndensities, or in that of a homogenous polar phase at higher densities.\nFurthermore, hydrodynamics protects the polar-liquid state from the giant\ndensity fluctuations. Our experiments demonstrate that genuine physical\ninteractions at the individual level are sufficient to set homogeneous active\npopulations into stable directed motion."
    },
    {
        "anchor": "Atomistic picture of fluorescent probes with hydrocarbon tails in lipid\n  bilayer membranes: an investigation of selective affinities and fluorescent\n  anisotropies in different environmental phases: By reverting to spectroscopy, changes in the biological environment of a\nfluorescent probe can be monitored and the presence of various phases of the\nsurrounding lipid bilayer membranes can be detected. This study highlights the\nimportant differences in orientation and location and therefore in efficiency\nbetween the probes when they are used in fluorescence microscopy to screen\nvarious lipid bilayer membrane phases. Dependent on the lipid composition, the\nangle between the transition state dipole moments of both probes and the normal\nto the membrane are found to deviate clearly from 90{\\deg}. It is seen that the\nDiI-C18(5) probe is located in the headgroup region of the SM:Chol mixture, in\nclose contact with water molecules. A fluorescence anisotropy study indicates\nalso that DiI-C18(5) gives rise to a distinctive behavior in the SM:Chol\nmembrane compared to the other considered membranes. The latter behavior has\nnot been seen for the studied BODIPY probe, which is located deeper in the\nmembrane.",
        "positive": "Effective elastic theory of smectic-A and smectic-C liquid crystals: We analytically derive the effective layer elastic energy of smectic-A and\nsmectic-C liquid crystals by adiabatic elimination of the orientational degree\nof freedom from the generalized Chen-Lubensky model. In the smectic-A phase,\nthe effective layer bending elastic modulus is calculated as a function of the\nwavelength of the layer undulation mode. It turns out that an unlocking of the\nlayer normal and the director reduces the layer bending rigidity for\nwavelengths smaller than the director penetration length. In the achiral\nsmectic-C phase, an anisotropic bending elasticity appears due to the coupling\nbetween the layer displacement and director. The effective layer bending\nrigidity is calculated as a function of the angle $\\vartheta$ between the layer\nundulation wave-vector and the director field. We compute the free energy\nminimizer $\\vartheta=\\theta$. It turns out that $\\theta$ varies from $0\\deg$ to\n$90\\deg$ depending on the tilt angle, undulation wave-length and other elastic\nconstants. We also discover a new important characteristic length and the\ndiscontinuous change of $\\theta$. Using the elastic constants of Chen-Lubensky\nmodel, we determine the parameters of the more macroscopic model [Y. Hatwalne\nand T. C. Lubensky, Phys. Rev. E {\\bf 52}, 6240 (1995)]. We then discuss the\nhydrodynamics, and demonstrate the alignment of director and the propagation of\nthe anisotropic layer displacement wave in the presence of an oscillatory wall\nand a vibrating cylindrical source respectively."
    },
    {
        "anchor": "On the absence of structure factors in concentrated colloidal\n  suspensions and nanocomposites: Small-angle scattering is a commonly used tool to analyze the dispersion of\nnanoparticles in all kinds of matrices. Besides some obvious cases, the\nassociated structure factor is often complex and cannot be reduced to a simple\ninterparticle interaction, like excluded volume only. In recent experiments, we\nhave encountered a surprising absence of structure factors (S(q) = 1) in\nscattering from rather concentrated polymer nanocomposites [A.-C. Genix et al,\nACS Appl. Mater. Interfaces 11 (2019) 17863]. In this case, quite pure form\nfactor scattering is observed. This somewhat ``ideal'' structure is further\ninvestigated here making use of reverse Monte Carlo simulations in order to\nshed light on the corresponding nanoparticle structure in space. By fixing the\ntarget ``experimental'' apparent structure factor to one over a given q-range\nin these simulations, we show that it is possible to find dispersions with this\nproperty. The influence of nanoparticle volume fraction and polydispersity has\nbeen investigated, and it was found that for high concentrations only a high\npolydispersity allows reaching a state of S = 1. The underlying structure in\nreal space is discussed in terms of the pair-correlation function, which\nevidences the importance of attractive interactions between polydisperse\nnanoparticles. The calculation of partial structure factors shows that there is\nno specific ordering of large or small particles, but that the presence of\nattractive interactions together with polydispersity allows reaching an almost\n``structureless'' state.",
        "positive": "Mutual Information in Molecular and Macromolecular Systems: The relaxation properties of viscous liquids close to their glass transition\n(GT) have been widely characterised by the statistical tool of time correlation\nfunctions. However, the strong influence of ubiquitous non-linearities calls\nfor new, alternative tools of analysis. In this respect, information\ntheory-based observables and, more specifically, mutual information (MI) are\ngaining increasing interest. Here, we report on novel, deeper insight provided\nby MI-based analysis of molecular dynamics simulations of molecular and\nmacromolecular glass-formers on two distinct aspects of transport and\nrelaxation close to GT, namely dynamical heterogeneity (DH) and secondary\nJohari--Goldstein (JG) relaxation processes. In a model molecular liquid with\nsignificant DH, MI reveals two populations of particles organised in clusters\nhaving either filamentous or compact globular structures that exhibit different\nmobility and relaxation properties. In a model polymer melt, MI provides\nclearer evidence of JG secondary relaxation and sharper insight into its DH. It\nis found that both DH and MI between the orientation and the displacement of\nthe bonds reach (local) maxima at the time scales of the primary and JG\nsecondary relaxation. This suggests that, in (macro)molecular systems, the\nmechanistic explanation of both DH and relaxation must involve\nrotation/translation coupling."
    },
    {
        "anchor": "Plectoneme creation reduces the rotational friction of a polymer: The torsional dynamics of a semiflexible polymer with a contour length $L$\nlarger than its persistence length L_p that is rotated at fixed frequency\nomega_0 at one end is studied by scaling arguments and hydrodynamic\nsimulations. We find a non-equilibrium transition at a critical frequency\nomega_*: In the linear regime, omega_0 < omega_*, axial spinning is the\ndominant dissipation mode. In the non-linear regime, omega_0 > omega_*, the\ntwist-dissipation mode involves the continuous creation of plectonemes close to\nthe driven end and the rotational friction is substantially reduced.",
        "positive": "Stress Relaxation in Entangled Polymer Melts: We present an extensive set of simulation results for the stress relaxation\nin equilibrium and step-strained bead-spring polymer melts. The data allow us\nto explore the chain dynamics and the shear relaxation modulus, $G(t)$, into\nthe plateau regime for chains with $Z=40$ entanglements and into the terminal\nrelaxation regime for $Z=10$. Using the known (Rouse) mobility of unentangled\nchains and the melt entanglement length determined via the primitive path\nanalysis of the microscopic topological state of our systems, we have performed\nparameter -free tests of several different tube models. We find excellent\nagreement for the Likhtman-McLeish theory using the double reptation\napproximation for constraint release, if we remove the contribution of\nhigh-frequency modes to contour length fluctuations of the primitive chain."
    },
    {
        "anchor": "Fokker-Planck description and diffusive phonon heat transport: We propose a prescription based on the Fokker-Planck equation in the\nStratonovich approach, with the diffusion coefficient dependent on temporal and\nspatial coordinates, for describing heat conduction by phonons in small\nstructures. This equation can be analytically solved for a broad class of\ndiffusion coefficients. It can also describe non-Gaussian processes. Further,\nit generalizes the model investigated by Naqvi and Waldenstr$\\phi $% m (PRL, 95\n(2005), 065901). We show that our solutions can fit well the results derived\nfrom the Boltzmann equation.",
        "positive": "Entanglement, elasticity and viscous relaxation of actin solutions: We have investigated the viscosity and the plateau modulus of actin solutions\nwith a magnetically driven rotating disc rheometer. For entangled solutions we\nobserved a scaling of the plateau modulus versus concentration with a power of\n7/5. The measured terminal relaxation time increases with a power 3/2 as a\nfunction of polymer length. We interpret the entanglement transition and the\nscaling of the plateau modulus in terms of the tube model for semiflexible\npolymers."
    },
    {
        "anchor": "Continuous breakdown of Purcell's scallop theorem with inertia: Purcell's scallop theorem defines the type of motions of a solid body -\nreciprocal motions - which cannot propel the body in a viscous fluid with zero\nReynolds number. For example, the flapping of a wing is reciprocal and, as was\nrecently shown, can lead to directed motion only if its frequency Reynolds\nnumber, Re_f, is above a critical value of order one. Using elementary\nexamples, we show the existence of oscillatory reciprocal motions which are\neffective for all arbitrarily small values of the frequency Reynolds number and\ninduce net velocities scaling as (Re_f)^\\alpha (alpha > 0). This demonstrates a\ncontinuous breakdown of the scallop theorem with inertia.",
        "positive": "Optimal packing of polydisperse hard-sphere fluids: We consider the effect of intermolecular interactions on the optimal\nsize-distribution of $N$ hard spheres that occupy a fixed total volume. When we\nminimize the free-energy of this system, within the Percus-Yevick\napproximation, we find that no solution exists beyond a quite low threshold\n($\\eta \\thickapprox 0.260$). Monte Carlo simulations reveal that beyond this\ndensity, the size-distribution becomes bi-modal. Such distributions cannot be\nreproduced within the Percus-Yevick approximation. We present a theoretical\nargument that supports the occurrence of a non-monotonic size-distribution and\nemphasizing the importance of finite size effects."
    },
    {
        "anchor": "Phase transitions and self-assemblies of lower diamondoids and\n  derivatives: Applying ab initio calculation and molecular dynamics simulation methods, we\nhave been calculating and predicting the essential self-assemblies and phase\ntransitions of two lower diamondoids (adamantane and diamantane), three of\ntheir important derivatives (amantadine, memantine and rimantadine), and two\norganometallic molecules that are built by substituting one hydrogen ion with\none sodium ion in both adamantane and diamantine molecules (ADM-Na and\nOptimized DIM-Na). To study their self-assembly and phase transition behaviors,\nwe built seven different MD simulation systems, and each system consisting of\n125 molecules. We obtained self-assembly structures and simulation trajectories\nfor the seven molecules. Radial distribution function studies showed clear\nphase transitions for the seven molecules. Higher aggregation temperatures were\nobserved for diamondoid derivatives. We also studied the density dependence of\nthe phase transition which demonstrates that the higher the density - the\nhigher the phase transition points.",
        "positive": "Thermotropic reentrant isotropy and antiferroelectricity in the\n  ferroelectric nematic material RM734: We report a transition from the ferroelectric nematic liquid crystal ($N_F$)\nphase to a lower-temperature, antiferroelectric fluid phase having reentrant\nisotropic symmetry ($I_A$), in the liquid crystal compound RM734 doped with\nsmall concentrations of the ionic liquids BMIM or EMIM. Even a trace amount of\nionic liquid dopant facilitates the kinetic pathway for the transition from the\n$N_F$ to the $I_A$, enabling simple cooling to produce this isotropic fluid\nphase rather than resulting in crystallization. The $I_A$ was also obtained in\nthe absence of specific ionic liquid doping by appropriate temperature cycling\nin three distinct, as-synthesized-and-purified batches of RM734, two commercial\nand one from our laboratory. An additional birefringent, lamellar-modulated,\nantiferroelectric phase with the director parallel to the layers, resembling\nthe smectic $Z_A$, is found between the paraelectric and ferroelectric nematic\nphases in RM734/BMIM mixtures."
    },
    {
        "anchor": "Transmission and reflection of strongly nonlinear solitary waves at\n  granular interfaces: The interaction of a solitary wave front with an interface formed by two\nstrongly-nonlinear non-cohesive granular lattices displays rich behaviour,\ncharacterized by the breakdown of continuum equations of motion in the vicinity\nof the interface. By treating the solitary wave as a quasiparticle with an\neffective mass, we construct an intuitive (energy and linear momentum\nconserving) discrete model to predict the amplitudes of the transmitted\nsolitary waves generated when an incident solitary wave front, parallel to the\ninterface, moves from a denser to a lighter granular hexagonal lattice. Our\nfindings are corroborated with simulations. We then successfully extend this\nmodel to oblique interfaces, where we find that the angle of refraction and\nreflection of a solitary wave follows, below a critical value, an analogue of\nSnell's law in which the solitary wave speed replaces the speed of sound, which\nis zero in the sonic vacuum.",
        "positive": "Memory of jamming - multiscale models for soft and granular matter: Soft, disordered, micro-structured materials are ubiquitous in nature and\nindustry, and are different from ordinary fluids or solids, with unusual,\ninteresting static and flow properties. The transition from fluid to solid -at\nthe so-called jamming density- features a multitude of complex mechanisms, but\nthere is no unified theoretical framework that explains them all. In this\nstudy, a simple yet quantitative and predictive model is presented, which\nallows for a variable, changing jamming density, encompassing the memory of the\ndeformation history and explaining a multitude of phenomena at and around\njamming. The jamming density, now introduced as a new state-variable, changes\ndue to the deformation history and relates the system's macroscopic response to\nits microstructure. The packing efficiency can increase logarithmically slow\nunder gentle repeated (isotropic) compression, leading to an increase of the\njamming density. In contrast, shear deformations cause anisotropy, changing the\npacking efficiency exponentially fast with either dilatancy or compactancy. The\nmemory of the system near jamming can be explained by a microstatistical model\nthat involves a multiscale, fractal energy landscape and links the microscopic\nparticle picture to the macroscopic continuum description, providing a unified\nexplanation for the qualitatively different flow-behavior for different\ndeformation modes. To complement our work, a recipe to extract the\nhistory-dependent jamming density from experimentally accessible data is\nproposed, and alternative state-variables are compared. The proposed simple\nmacroscopic constitutive model is calibrated with the memory of microstructure.\nSuch approach can help understanding predicting and mitigating failure of\nstructures or geophysical hazards, and will bring forward industrial process\ndesign/optimization, and help solving scientific challenges in fundamental\nresearch."
    },
    {
        "anchor": "Rheology of Cubic Blue Phases: We study the behaviour of cubic blue phases under shear flow via lattice\nBoltzmann simulations. We focus on the two experimentally observed phases, Blue\nPhase I (BPI) and Blue Phase II (BPII). The disclination network of Blue Phase\nII continuously breaks and reforms under steady shear, leading to an\noscillatory stress response in time. For larger shear rates, the structure\nbreaks up into a Grandjean texture with a cholesteric helix lying along the\nflow gradient direction. Blue Phase I leads to a very different response. Here,\noscillations are only possible for intermediate shear rates -- very slow flow\ncauses a transition of the initially ordered structure into an amorphous\nnetwork with an apparent yield stress. Larger shear rates lead to another\namorphous state with different structure of the defect network. For even larger\nflow rates the same break-up into a Grandjean texture as for Blue Phase II is\nobserved. At the highest imposed flow rates both cubic blue phases adopt a\nflow-aligned nematic state. Our results provide the first theoretical\ninvestigation of sheared blue phases in large systems, and are relevant to\nunderstanding the bulk rheology of these materials.",
        "positive": "On Stretching, Bending, Shearing and Twisting of Actin Filaments II:\n  Multi-Resolution Modelling: We present a multi-resolution methodology for modelling F-actin filaments. It\nprovides detailed microscopic information at the level of individual monomers\nat a lower computational cost by replacing the monomer-based model in parts of\nthe simulated filament by a rod-based macroscopic model. In the monomer-based\ndescription, G-actin is represented by ellipsoids bound at the surface in a\ndouble helical configuration to form F-actin. The rod-based model is coarser,\nin which F-actin is described using a Cosserat model, as seen in the preceding\npaper [arXiv:2112.01480]. The multi-resolution methodology is illustrated using\nthree case studies, designed to test the properties of F-actin under\nstretching, bending, shearing and twisting. The methodology is especially\nsuited for situations where filaments are subject to bending deformations. We\ninvestigate the limitations of using the standard Cosserat model to capture the\ncomplete torsional behaviour of F-actin, presenting its extensions which\naccount for curvature dependent rigidities and a twist-stretch coupling to\nimprove accuracy of the overall multi-resolution scheme."
    },
    {
        "anchor": "Delineation of the Native Basin in Continuum Models of Proteins: We propose two approaches for determining the native basins in off-lattice\nmodels of proteins. The first of them is based on exploring the saddle points\non selected trajectories emerging from the native state. In the second\napproach, the basin size can be determined by monitoring random distortions in\nthe shape of the protein around the native state. Both techniques yield the\nsimilar results. As a byproduct, a simple method to determine the folding\ntemperature is obtained.",
        "positive": "Model microswimmers in channels with varying cross section: We study different types of microswimmers moving in channels with varying\ncross section and thereby interacting hydrodynamically with the channel walls.\nStarting from the Smoluchowski equation for a dilute suspension, for which\ninteractions among swimmers can be neglected, we derive analytic expressions\nfor the lateral probability distribution between plane channel walls. For\nweakly corrugated channels we extend the Fick--Jacobs approach to microswimmers\nand thereby derive an effective equation for the probability distribution along\nthe channel axis. Two regimes arise dominated either by entropic forces due to\nthe geometrical confinement or by the active motion. In particular, our results\nshow that the accumulation of microswimmers at channel walls is sensitive to\nboth, the underlying swimming mechanism and the geometry of the channels.\nFinally, for asymmetric channel corrugation our model predicts a rectification\nof microswimmers along the channel, the strength and direction of which\nstrongly depends on the swimmer type."
    },
    {
        "anchor": "Simulation of granular jet: Is granular flow really a \"perfect fluid?\": We perform three-dimensional simulations of a granular jet impact for both\nfrictional and frictionless grains. Small shear stress observed in the\nexperiment[X. Cheng et al., Phys. Rev. Lett. 99, 188001 (2007) ] is reproduced\nthrough our simulation. However, the fluid state after the impact is far from a\nperfect fluid, and thus, similarity between granular jets and quark gluon\nplasma is superficial, because the observed viscosity is finite and its value\nis consistent with the prediction of the kinetic theory.",
        "positive": "Effect of salt concentration on the stability of heterogeneous DNA: We study the role of cations on the stability of double stranded DNA (dsDNA)\nmolecules.It is known that the two strands of double stranded DNA(dsDNA) have\nnegative charge due to phosphate group. Cations in the form of salt in the\nsolution, act as shielding agents thereby reducing the repulsion between these\nstrands. We study several heterogeneous DNA molecules. We calculate the phase\ndiagrams for DNA molecules in thermal as well as in force ensembles using\nPeyrard-Bishop-Dauxois (PBD) model. The dissociation and the stacking energies\nare the two most important factors that play an important role in the DNA\nstability. With suitable modifications in the model parameters we investigate\nthe role of cation concentration on the stability of different heterogeneous\nDNA molecules. The objective of this work is to understand how these cations\nmodify the strength of different pairs or bases along the strand. The phase\ndiagram for the force ensemble case (a dsDNA is pulled from an end) is compared\nwith the experimental results."
    },
    {
        "anchor": "Van der Waals torque and force between dielectrically anisotropic\n  layered media: We analyse van der Waals interactions between a pair of dielectrically\nanisotropic plane-layered media interacting across a dielectrically isotropic\nsolvent medium. We develop a general formalism based on transfer matrices to\ninvestigate the van der Waals torque and force in the limit of weak\nbirefringence and dielectric matching between the ordinary axes of the\nanisotropic layers and the solvent. We apply this formalism to study the\nfollowing systems: (i) a pair of single anisotropic layers, (ii) a single\nanisotropic layer interacting with a multilayered slab consisting of\nalternating anisotropic and isotropic layers, and (iii) a pair of multilayered\nslabs each consisting of alternating anisotropic and isotropic layers, looking\nat the cases where the optic axes lie parallel and/or perpendicular to the\nplane of the layers. For the first case, the optic axes of the oppositely\nfacing anisotropic layers of the two interacting slabs generally possess an\nangular mismatch, and within each multilayered slab the optic axes may either\nbe the same, or undergo constant angular increments across the anisotropic\nlayers. In particular, we examine how the behaviors of the van der Waals torque\nand force can be \"tuned\" by adjusting the layer thicknesses, the relative\nangular increment within each slab, and the angular mismatch between the slabs.",
        "positive": "The Role of Nonlinear Friction in the Dewetting of Thin Film Polymers: The study of the dewetting of very thin polymer films has recently revealed\nmany unexpected features (e.g. unusual rim morphologies and front velocities)\nwhich have been the focus of several theoretical models. Surprisingly, the most\nstriking feature of all, that is a decrease of the rim width with time, have\nnot yet been explained. In the present letter, we show how the combined effects\nof a non-linear friction between the film and the substrate, and the presence\nof residual stresses within the film, result in the presence of a maximum in\nthe time evolution of the rim width. In addition, we show how the introduction\nof a non-linear friction can also simply explain the rapid decrease of the\ndewetting velocity with time observed experimentally."
    },
    {
        "anchor": "Interface-induced hysteretic volume phase transition of microgels:\n  simulation and experiment: Thermo-responsive microgel particles can exhibit a drastic volume shrinkage\nupon increasing the solvent temperature. Recently we found that the spreading\nof poly(N-isopropylacrylamide)(PNiPAm) microgels at a liquid interface under\nthe influence of surface tension hinders the temperature-induced volume phase\ntransition. In addition, we observed a hysteresis behavior upon temperature\ncycling, i.e. a different evolution in microgel size and shape depending on\nwhether the microgel was initially adsorbed to the interface in expanded or\ncollapsed state. Here, we model the volume phase transition of such microgels\nat an air/water interface by monomer-resolved Brownian dynamics simulations and\ncompare the observed behavior with experiments. We reproduce the experimentally\nobserved hysteresis in the microgel dimensions upon temperature variation. Our\nsimulations did not observe any hysteresis for microgels dispersed in the bulk\nliquid, suggesting that it results from the distinct interfacial morphology of\nthe microgel adsorbed at the liquid interface. An initially collapsed microgel\nbrought to the interface and subjected to subsequent swelling and collapsing\n(resp. cooling and heating) will end up in a larger size than it had in the\noriginal collapsed state. Further temperature cycling, however, only shows a\nmuch reduced hysteresis, in agreement with our experimental observations. We\nattribute the hysteretic behavior to a kinetically trapped initial collapsed\nconfiguration, which relaxes upon expanding in the swollen state. We find a\nsimilar behavior for linear PNiPAm chains adsorbed to an interface. Our\ncombined experimental - simulation investigation provides new insights into the\nvolume phase transition of PNiPAm materials adsorbed to liquid interfaces.",
        "positive": "Accurate determination of the translational correlation function of\n  two-dimensional solids: The identification of the different phases of a two-dimensional (2d) system,\nwhich might be in solid, hexatic, or liquid, requires the accurate\ndetermination of the correlation function of the translational and of the\nbond-orientational order parameters. According to the\nKosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory, in the solid phase\nthe translational correlation function decays algebraically, as a consequence\nof the Mermin-Wagner long-wavelength fluctuations. Recent results have however\nreported an exponential-like decay. By revisiting different definitions of the\ntranslational correlation function commonly used in the literature, here we\nclarify that the observed exponential-like decay in the solid phase results\nfrom an inaccurate determination of the symmetry axis of the solid; the\nexpected power-law behaviour is recovered when the symmetry axis is properly\nidentified. We show that, contrary to the common assumption, the symmetry axis\nof a 2d solid is not fixed by the direction of its global bond-orientational\nparameter, and introduce an approach allowing to determine the symmetry axis\nfrom a real space analysis of the sample."
    },
    {
        "anchor": "Compressed correlation functions and fast aging dynamics in metallic\n  glasses: We present x-ray photon correlation spectroscopy measurements of the atomic\ndynamics in a Zr67Ni33 metallic glass, well below its glass transition\ntemperature. We find that the decay of the density fluctuations can be well\ndescribed by compressed, thus faster than exponential, correlation functions\nwhich can be modeled by the well-known Kohlrausch-Williams-Watts function with\na shape exponent {\\beta} larger than one. This parameter is furthermore found\nto be independent of both waiting time and wave-vector, leading to the\npossibility to rescale all the correlation functions to a single master curve.\nThe dynamics in the glassy state is additionally characterized by different\naging regimes which persist in the deep glassy state. These features seem to be\nuniversal in metallic glasses and suggest a non diffusive nature of the\ndynamics. This universality is supported by the possibility of describing the\nfast increase of the structural relaxation time with waiting time using a\nunique model function, independently of the microscopic details of the system.",
        "positive": "Self-assembly of amphiphilic Janus particles at planar walls: A density\n  functional study: We investigate the structure formation of amphiphilic molecules at planar\nwalls using density functional theory. The molecules are modeled as (hard)\nspheres composed of a hydrophilic and hydrophobic part. The orientation of the\nresulting Janus-particles is described as a vector representing an internal\ndegree of freedom. Our density functional approach involves Fundamental Measure\nTheory combined with a mean-field approximation for the anisotropic\ninteraction. Considering neutral, hydrophilic and hydrophobic walls, we study\nthe adsorption of the particles, focussing on the competition between the\nsurface field and interact ion-induced ordering phenomena. Finally, we consider\nsystems confined between two planar walls. It is shown that the anisotropic\nJanus interaction yields pronounced frustration effects at low temperatures."
    },
    {
        "anchor": "Heterogeneity and patterning in the quasi-static behavior of granular\n  materials: Heterogeneity is classified in five categories---topologic, geometric,\nkinematic, static, and constitutive---and the first four categories are\ninvestigated in a numerical DEM simulation of biaxial compression. The\nsimulation experiments show that the topology and geometric fabric become more\nvariable during loading. The measured fluctuations in inter-particle movements\nare large, they increase with loading, and they extend to distances of at least\neight particle diameters. Deformation and rotation heterogeneity are large and\nare expressed in spatial patterning. Stress heterogeneity is moderate\nthroughout loading.",
        "positive": "Variational approach for electrolyte solutions: from dielectric\n  interfaces to charged nanopores: A variational theory is developed to study electrolyte solutions, composed of\ninteracting point-like ions in a solvent, in the presence of dielectric\ndiscontinuities and charges at the boundaries. Three important and non-linear\nelectrostatic effects induced by these interfaces are taken into account:\nsurface charge induced electrostatic field, solvation energies due to the ionic\ncloud, and image charge repulsion. Our variational equations thus go beyond the\nmean-field theory. The influence of salt concentration, ion valency, dielectric\njumps, and surface charge is studied in two geometries. i) A single neutral\nair-water interface with an asymmetric electrolyte. A charge separation and\nthus an electrostatic field gets established due to the different image charge\nrepulsions for coions and counterions. Both charge distributions and surface\ntension are computed and compared to previous approximate calculations. For\nsymmetric electrolyte solutions close to a charged surface, two zones are\ncharacterized. In the first one, with size proportional to the logarithm of the\ncoupling parameter, strong image forces impose a total ion exclusion, while in\nthe second zone the mean-field approach applies. ii) A symmetric electrolyte\nconfined between two dielectric interfaces as a simple model of ion rejection\nfrom nanopores. The competition between image charge repulsion and attraction\nof counterions by the membrane charge is studied. For small surface charge, the\ncounterion partition coefficient decreases with increasing pore size up to a\ncritical pore size, contrary to neutral membranes. For larger pore sizes, the\nwhole system behaves like a neutral pore. The prediction of the variational\nmethod is also compared with MC simulations and a good agreement is observed."
    },
    {
        "anchor": "The behavior of capillary suspensions at diverse length scales: from\n  single capillary bridges to bulk: Liquid-liquid-solid systems are becoming increasingly common in everyday life\nwith many possible applications. Here, we focus on a special case of such\nliquid-liquid-solid systems, namely, capillary suspensions. These capillary\nsuspensions originate from particles that form a network based on capillary\nforces and are typically composed of solids in a bulk liquid with an added\nsecondary liquid. The structure of particle networks based on capillary bridges\npossesses unique properties compared with networks formed via other attractive\ninteractions where these differences are inherently related to the properties\nof the capillary bridges, such as bridge breaking and coalescence between\nadjacent bridges. Thus, to tailor the mechanical properties of capillary\nsuspensions to specific requirements, it is important to understand the\ninfluences on different length scales ranging from the dynamics of the bridges\nwith varying external stimuli to the often heterogeneous network structure.",
        "positive": "Nonequilibrium phase transitions in active contractile polar filaments: We study the patterning and fluctuations of a collection of active\ncontractile polar filaments on a two dimensional substrate, using a continuum\ndescription in the presence of athermal noise, parameterised by an active\ntemperature $T_A$. The steady states generically consist of arrays of inward\npointing asters and show a continuous transition from a moving aster street to\na stationary aster lattice. In contrast to its equilibrium counterpart, this\nactive crystal shows true long range order at low $T_A$. On increasing $T_A$,\nthe asters remodel with a distribution of lifetimes; concomitantly we find\nnovel phase transitions characterised by polar and bond-orientational order."
    },
    {
        "anchor": "Topological sound in active-liquid metamaterials: Liquids composed of self-propelled particles have been experimentally\nrealized using molecular, colloidal, or macroscopic constituents. These active\nliquids can flow spontaneously even in the absence of an external drive. Unlike\nspontaneous active flow, the propagation of density waves in confined active\nliquids is not well explored. Here, we exploit a mapping between density waves\non top of a chiral flow and electrons in a synthetic gauge field to lay out\ndesign principles for artificial structures termed topological active\nmetamaterials. We design metamaterials that break time-reversal symmetry using\nlattices composed of annular channels filled with a spontaneously flowing\nactive liquid. Such active metamaterials support topologically protected sound\nmodes that propagate unidirectionally, without backscattering, along either\nsample edges or domain walls and despite overdamped particle dynamics. Our work\nillustrates how parity-symmetry breaking in metamaterial structure combined\nwith microscopic irreversibility of active matter leads to novel\nfunctionalities that cannot be achieved using only passive materials.",
        "positive": "The structure of the perturbation series of the spin-1 Bose gas at low\n  temperatures: The properties of Green's functions and various correlation functions of\ndensity and spin operators are considered in a homogeneous spin-1 Bose gas in\ndifferent phases. The dielectric formalism is worked out and the partial\ncoincidence of the one-particle and collective spectra is pointed out below the\ntemperature of Bose-Einstein condensation. As an application the formalism is\nused to give two approximations for the propagators and the correlation\nfunctions and the spectra of excitations including shifts and widths due to the\nthermal cloud."
    },
    {
        "anchor": "Tuning Stoichiometry to Promote Formation of Binary Colloidal\n  Superlattices: The self-assembly of binary nanoparticle superlattices from colloidal\nmixtures is a promising method for the fabrication of complex colloidal\nco-crystal structures. However, binary mixtures often form amorphous or\nmetastable phases instead of the thermodynamically stable phase. Here we show\nthat in binary mixtures of differently sized spherical particles, an excess of\nthe smaller component can promote -- and, in some cases, may be necessary for\n-- the self-assembly of a binary co-crystal. Using computer simulations, we\nidentify two mechanisms responsible for this phenomenon. First, excess small\nparticles act like plasticizers and enable systems to reach a greater\nsupersaturation before kinetic arrest occurs. Second, they can disfavor\ncompeting structures that may interfere with the growth of the target\nstructure. We find the phase behavior of simulated mixtures of hard spheres\nclosely matches published experimental results. We demonstrate the generality\nof our findings for mixtures of particles of arbitrary shape by presenting a\nbinary mixture of hard shapes that only self-assembles with an excess of the\nsmaller component. mixtures of particles of arbitrary shape by presenting a\nbinary mixture of hard shapes that only self-assembles with an excess of the\nsmaller component.",
        "positive": "Continuous Isotropic-Nematic transition in compressed rod-like based\n  nanocolloid: Landau - de Gennes mean field model predicts the discontinuous transition for\nthe Isotropic - Nematic transition, associated with uniaxial and quadrupolar\norder parameter in three dimensions. This report shows pressure-related\ndielectric studies for rod-like nematogenic pentylcyanobiphenyl (5CB) and its\nnanocolloids with BaTiO3 nanoparticles. The scan of dielectric constant\nrevealed the continuous I-N transition in a compressed nanocolloid with a tiny\namount of nanoparticles (x=0.1%). For the nematic phase in 5CB and its x=1%\nnanocolloid the enormous values of dielectric constant and the bending-type\nlong-range pretransitional behavior were detected. The 'shaping' influence of\npretransitional fluctuations was also detected for the ionic-related\ncontribution to dielectric permittivity in the isotropic phase. For the\nhigh-frequency relaxation domain, this impact was tested for the primary\nrelaxation time and the translational-orientaional decoupling."
    },
    {
        "anchor": "Geometry-induced phase transition in fluids: capillary prewetting: We report a new first-order phase transition preceding capillary condensation\nand corresponding to the discontinuous formation of a curved liquid meniscus.\nUsing a mean-field microscopic approach based on the density functional theory\nwe compute the complete phase diagram of a prototypical two-dimensional system\nexhibiting capillary condensation, namely that of a fluid with long-ranged\ndispersion intermolecular forces which is spatially confined by a substrate\nforming a semi-infinite rectangular pore exerting long-ranged dispersion forces\non the fluid. In the T-mu plane the phase line of the new transition is\ntangential to the capillary condensation line at the capillary wetting\ntemperature, Tcw. The surface phase behavior of the system maps to planar\nwetting with the phase line of the new transition, termed capillary prewetting,\nmapping to the planar prewetting line. If capillary condensation is approached\nisothermally with T>Tcw, the meniscus forms at the capping wall and unbinds\ncontinuously, making capillary condensation a second-order phenomenon. We\ncompute the corresponding critical exponent for the divergence of adsorption.",
        "positive": "Stripe Systems with Competing Interactions on Quasi-One Dimensional\n  Periodic Substrates: We numerically examine the two-dimensional ordering of a stripe forming\nsystem of particles with competing long-range repulsion and short-range\nattraction in the presence of a quasi-one-dimensional corrugated substrate. As\na function of increasing substrate strength or the ratio of the number of\nparticles to the number of substrate minima we show that a remarkable variety\nof distinct orderings can be realized, including modulated stripes, prolate\nclump phases, two dimensional ordered kink structures, crystalline void phases,\nand smectic phases. Additionally in some cases the stripes align perpendicular\nto the substrate troughs. Our results suggest that a new route to self assembly\nfor systems with competing interactions can be achieved through the addition of\na simple periodic modulated substrate."
    },
    {
        "anchor": "Albe 1998 - La grande Motte 2009 : quelles avanc\u00e9es en diffusion de\n  neutrons aux petits angles en 10 ans ?: The importance of neutron scattering techniques for the characterization of\nsamples in soft condensed matter has been demonstrated all along the present\nbook. The fine understanding of the physical properties is closely linked to\nprogress in the field of instrumentation. This chapter describes the advances\nover the last decade in technical domains, such as neutron detection,\nelectronics and sample environment. The news software for data reduction and\nanalysis are also discussed before to conclude with the ILL and LLB projects\nfor new instruments.",
        "positive": "Equilibration and aging of dense soft-sphere glass-forming liquids: The recently-developed non-equilibrium extension of the self-consistent\ngeneralized Langevin equation theory of irreversible relaxation [Phys. Rev. E\n(2010) 82, 061503; ibid. 061504] is applied to the description of the\nirreversible process of equilibration and aging of a glass-forming soft-sphere\nliquid that follows a sudden temperature quench, within the constraint that the\nlocal mean particle density remains uniform and constant. For these particular\nconditions, this theory describes the non-equilibrium evolution of the static\nstructure factor S(k;t) and of the dynamic properties, such as the\nself-intermediate scattering function F_S(k,\\tau;t), where tau is the\ncorrelation delay time and t is the evolution or waiting time after the quench.\nSpecific predictions are presented, for the deepest quench (to zero\ntemperature). The predicted evolution of the alpha-relaxation time\n\\tau_\\alpha(t) as a function of t allows us to define the equilibration time\nt^{eq}, as the time after which \\tau_\\alpha has attained its equilibrium value\n\\tau_\\alpha^{eq}. It is predicted that both, t^{eq}(\\phi) and\n\\tau_{\\alpha}^{eq}, diverge as \\phi \\to \\phi^{(a)}, where \\phi^{(a)} is the\nhard-sphere dynamic-arrest volume fraction \\phi^{(a)}\\ (\\approx 0.582), thus\nsuggesting that the measurement of equilibrium properties at and above\n\\phi^{(a)} is experimentally impossible."
    },
    {
        "anchor": "Structural crossover in a model fluid exhibiting two length scales:\n  repercussions for quasicrystal formation: We investigate the liquid state structure of the two-dimensional (2D) model\nintroduced by Barkan et al. [Phys. Rev. Lett. 113, 098304 (2014)], which\nexhibits quasicrystalline and other unusual solid phases, focussing on the\nradial distribution function $g(r)$ and its asymptotic decay $r\\to\\infty$. For\nthis particular model system, we find that as the density is increased there is\na structural crossover from damped oscillatory asymptotic decay with one\nwavelength to damped oscillatory asymptotic decay with another distinct\nwavelength. The ratio of these wavelengths is $\\approx1.932$. Following the\nlocus in the phase diagram of this structural crossover leads directly to the\nregion where quasicrystals are found. We argue that identifying and following\nsuch a crossover line in the phase diagram towards higher densities where the\nsolid phase(s) occur is a good strategy for finding quasicrystals in a wide\nvariety of systems. We also show how the pole analysis of the asymptotic decay\nof equilibrium fluid correlations is intimately connected with the\nnon-equilibrium growth or decay of small amplitude density fluctuations in a\nbulk fluid.",
        "positive": "Monostable Super Antiwettability: Super-antiwettability is an extreme situation of wetting where liquids stay\nat the tops of rough surfaces, in the so-called Cassie state1. Owing to the\ndramatic reduction of solid/liquid contact, it has many applications, such as\nantifouling2,3, droplet manipulation4,5, and self-cleaning6-9. However,\nsuper-antiwettability is often destroyed by impalement transitions caused by\nenvironmental disturbances10-16 while inverse transitions without energy input\nhave never been observed12,17-21. Here we show through controlled experiments\nthat there is a \"monostable\" region in the phase space of the receding contact\nangle and roughness parameters where transitions between (impaled) Wenzel and\nCassie states can be reversible. We describe the transition mechanism and\nestablish a simple criterion that predicts the experimentally observed\nWenzel-to-Cassie transitions for different liquids placed on\nmicropost-patterned substrates. These results can guide for designing and\nengineering robust super-antiwetting surfaces."
    },
    {
        "anchor": "Experimental and numerical study of the effect of surface patterning on\n  the frictional properties of polymer surfaces: We describe benchmark experiments to evaluate the frictional properties of\nlaser patterned low-density polyethylene as a function of sliding velocity,\nnormal force and humidity. The pattern is a square lattice of square cavities\nwith sub-mm spacing. We find that dynamic friction decreases compared to\nnon-patterned surfaces, since stress concentrations lead to anticipated\ndetachment, and that stick-slip behavior is also affected. Friction increases\nwith humidity, and the onset of stick-slip events occurs in the high humidity\nregime. Experimental results are compared with numerical simulations of a\nsimplified 2-D spring-block model. A good qualitative agreement can be obtained\nby introducing a deviation from the linear behavior of the Amontons-Coulomb law\nwith the load, due to a saturation in the effective contact area with pressure.\nThis also leads also to the improvement of the quantitative results of the\nspring-block model by reducing the discrepancy with the experimental results,\nindicating the robustness of the adopted simplified approach, which could be\nadopted to design patterned surfaces with controlled friction properties.",
        "positive": "Formation and Interaction of Membrane Tubes: We show that the formation of membrane tubes (or membrane tethers), which is\na crucial step in many biological processes, is highly non-trivial and involves\nfirst order shape transitions. The force exerted by an emerging tube is a\nnon-monotonic function of its length. We point out that tubes attract each\nother, which eventually leads to their coalescence. We also show that detached\ntubes behave like semiflexible filaments with a rather short persistence\nlength. We suggest that these properties play an important role in the\nformation and structure of tubular organelles."
    },
    {
        "anchor": "Compression-induced continuous phase transition in the buckling of a\n  semiflexible filament for two and three dimensions: The ability of biomolecules to exert forces on their surroundings or resist\ncompression from the environment is essential in a variety of biologically\nrelevant contexts. As has been understood for centuries, slender rods can only\nbe compressed so far until they buckle, adopting an intrinsically bent state\nthat may be unable to bear a compressive load. In the low-temperature limit and\nfor a constant compressive force, Euler buckling theory predicts a sudden\ntransition from a compressed to a bent state in these slender rods. In this\npaper, we use a mean-field theory to show that if a semiflexible chain is\ncompressed at a finite temperature with a fixed end-to-end distance (permitting\nfluctuations in the compressive forces), it exhibits a continuous phase\ntransition to a buckled state at a critical level of compression, and we\ndetermine a quantitatively accurate prediction of the transverse position\ndistribution function of the midpoint of the chain that indicates the\ntransition. We find the mean compressive forces are non-monotonic as the\nextension of the filament varies, consistent with the observation that strongly\nbuckled filaments are less able to bear an external load. We also find that for\nthe fixed extension (isometric) ensemble that the buckling transition does not\ncoincide with the local minimum of the mean force (in contrast to Euler\nbuckling). We also show the theory is highly sensitive to fluctuations in\nlength, and that the buckling transition can still be accurately recovered by\naccounting for those fluctuations. These predictions may be useful in\nunderstanding the behavior of filamentous biomolecules compressed by\nfluctuating forces, relevant in a variety of biological contexts.",
        "positive": "Temperature dependence of the nematic anchoring energy:mean field\n  analysis: In the mean field approximation, we evaluate the temperature dependence of\nthe anchoring energy strength of a nematic liquid crystal in contact with a\nsolid substrate due to thermal fluctuations. Our study is limited to the weak\nanchoring case, where the microscopic surface energy is small with respect to\nthe mean field energy due to the nematic phase. We assume furthermore that the\nphysical properties of the substrate can be considered temperature independent\nin the range of the nematic phase. According to the thermodynamical\nperturbative approach, the macroscopic surface energy is deduced by averaging\nthe microscopic one, with a density matrix containing only the nematic mean\nfield. We show that the thermal renormalization of the anchoring energy\ncoefficients is proportional to the generalized nematic order parameters."
    },
    {
        "anchor": "Shear thickening regimes of dense non-Brownian suspensions: We propose a unifying rheological framework for dense suspensions of\nnon-Brownian spheres, predicting the onsets of particle friction and particle\ninertia as distinct shear thickening mechanisms, while capturing quasistatic\nand soft particle rheology at high volume fractions and shear rates\nrespectively. Discrete element method simulations that take suitable account of\nhydrodynamic and particle-contact interactions corroborate the model\npredictions, demonstrating both mechanisms of shear thickening, and showing\nthat they can occur concurrently with carefully selected particle surface\nproperties under certain flow conditions. Microstructural transitions\nassociated with frictional shear thickening are presented. We find very\ndistinctive divergences of both the microstructural and dynamic variables with\nrespect to volume fraction in the thickened and non-thickened states.",
        "positive": "Poisson-Boltzmann formulary: Second edition: The Poisson-Boltzmann (PB) equation provides a mean-field theory of\nelectrolyte solutions at interfaces and in confinement, with numerous\napplications ranging from colloid science to nanofluidics. This formulary\ngathers important formulas for the PB description of a Z:Z electrolyte solution\ninside slit and cylindrical channels. Different approximated solutions (thin\nelectrical double layers, no co-ion, Debye-H\\\"uckel, and homogeneous/parabolic\npotential limits) and their range of validity are discussed, together with the\nfull solution for the slit channel. In addition, different boundary conditions\nare presented, the limits of the PB framework are briefly discussed, and Python\nscripts to solve the PB equation numerically are provided."
    },
    {
        "anchor": "Assur graphs, marginally jammed packings, and reconfigurable\n  metamaterials: Isostatic frames are mechanical networks that are simultaneously rigid and\nfree of self-stress states, and is a powerful concept in understanding phase\ntransitions in soft matter and designing of mechanical metamaterials. Here we\nanalyze substructures of isostatic frames, by generalizing ``Assur graphs'' to\nthe torus and examine them in physical systems. We show that the contact\nnetwork of marginally jammed packings approach torus Assur graphs in the\nthermodynamic limit, and demostrate how Assur graphs offer a new design\nprinciple for mechanical metamaterials in which motion and stress can propagate\nin reconfigurable pathways, while rigidity of the entire structure is\nmaintained.",
        "positive": "Capillary Contact Angle in a Completely Wet Groove: We consider the phase equilibria of a fluid confined in a deep capillary\ngroove of width $L$ with identical side walls and a bottom made of a different\nmaterial. All walls are completely wet by the liquid. Using density functional\ntheory and interfacial models, we show that the meniscus separating liquid and\ngas phases at two phase capillary-coexistence meets the bottom capped end of\nthe groove at a capillary contact angle $\\theta^{\\rm cap}(L)$ which depends on\nthe difference between the Hamaker constants. If the bottom wall has a weaker\nwall-fluid attraction than the side walls, then $\\theta^{\\rm cap}>0$ even\nthough all the isolated walls are themselves completely wet. This alters the\ncapillary condensation transition which is now first-order; this would be\ncontinuous in a capped capillary made wholly of either type of material. We\nshow that the capillary contact angle $\\theta^{\\rm cap}(L)$ vanishes in two\nlimits, corresponding to different capillary wetting transitions. These occur\nas the width i) becomes macroscopically large, and ii) is reduced to a\nmicroscopic value determined by the difference in Hamaker constants. This\nsecond wetting transition is characterised by large scale fluctuations and\nessential critical singularities arising from marginal interfacial\ninteractions."
    },
    {
        "anchor": "Conical instabilities on paper: The stability of the fundamental defects of an unstretchable flat sheet is\nexamined. This involves expanding the bending energy to second order in\ndeformations about the defect. The modes of deformation occur as eigenstates of\na fourth-order linear differential operator. Unstretchability places a global\nlinear constraint on these modes. Conical defects with a surplus angle exhibit\nan infinite number of states. If this angle is below a critical value, these\nstates possess an n-fold symmetry labeled by an integer, n \\geq 2. A nonlinear\nstability analysis shows that the 2-fold ground state is stable, whereas\nexcited states possess 2(n - 2) unstable modes which come in even and odd\npairs.",
        "positive": "Onset of Irreversibility and Chaos in Amorphous Solids Under Periodic\n  Shear: An important aspect of the physics of amorphous solids is the onset of\nirreversible behavior usually associated with yield. Here we study amorphous\nsolids under periodic shear using quasi-static molecular dynamics simulations\nand observe a transition from reversible to irreversible deformation at a\ncritical strain amplitude. We find that for small strain amplitudes the system\nexhibits a noisy but repetitive limit-cycle, similar to return point memory\n\\cite{sethna1993hysteresis}. However, for large strain amplitudes the behavior\nbecomes chaotic (shows sensitivity to initial conditions) and thus\nirreversible. We show that the chaotic behavior is a result of the shear band\ninstabilities that arise for large strains and the convective displacement\nfields they create."
    },
    {
        "anchor": "Correlations of non-affine displacements in metallic glasses through the\n  yield transition: We study correlations of non-affine displacement during simple shear\ndeformation of Cu-Zr bulk metallic glasses in molecular dynamics calculations.\nIn the elastic regime, our calculations show exponential correlation with a\ndecay length that we interpret as the size of a shear transformation zone in\nthe elastic regime. This correlation length becomes system-size dependent\nbeyond the yield transition as our calculation develops a shear band,\nindicative of a diverging length scale. We interpret these observations in the\ncontext of a recent proposition of yield as a first-order phase transition.",
        "positive": "Electrostatically assisted macroion association: A model system of highly asymmetric polyelectrolyte with directional\nshort-range attractive interactions was studied by canonical Monte Carlo\ncomputer simulations. Comparison of MC data with previously published\ntheoretical results shows good agreement. For moderate values of binding\nenergies, which matches those of molecular docking, a dynamic equilibrium\nbetween free and dimerized macroions is observed. Fraction of dimerized\nmacroions depends on macroion concentration, binding energy magnitude, and on\nthe valency of small counterions. Divalent counterions induce an effective\nattraction between macroions and enhance dimerization. This effect is most\nnotable at low to moderate macroion concentrations."
    },
    {
        "anchor": "Mechanical and geometrical properties of jammed wet granular materials: We numerically investigate the mechanical and geometrical properties of dense\nwet granular particles with irreversible attractive interaction. The shear\nmodulus exhibits two inflection points as the packing fraction increases, and\nthe bulk modulus shows a non-monotonic behavior. The coordination number also\nexhibits two inflection points. The peak position in the pair correlation\nfunction shifts to a lower value due to attractive interaction. The Voronoi\ntessellation of the particle configuration reveals that the probability density\nfunction for the volume of the Voronoi cell broadens as the packing fraction\napproaches the jamming point.",
        "positive": "Lattice of infinite bending-resistant fibers: This article present the double-periodical lattice made of infinite elastic\nfibers that withstand bending and tension. The model describes the elastic\nproperties of flat periodic structure. With this model the behavior of a\ntwo-dimensional array of infinite fibers is simulated. The material that\ncontains a row of broken fibers is considered. These broken fibers form the\nfailure in the material that shapes like a long straight crack. The lattice is\ntensioned in the direction, which is orthogonal to the direction of straight\ncrack. The conditions of fracture of this lattice are investigated. The closed\nform expression for the stress in the first unbroken fiber and the expression\nfor fracture toughness are given. These values are the functions of mechanical\nparameters of lattice and tensions in both families of fibers. The closed form\nsolution demonstrates a notable behavior of the material. Namely, the fracture\nbehavior of two-dimensional lattice is cardinally depends upon the pre-stress\nin the material in the direction, parallel to crack direction. If the tension\nin fibers that parallel to the crack direction exists, it stabilizes the crack\ngrowth and makes the load distribution in the unbroken fibers more even. The\ntwo-dimensional lattice behaves in the presence of tension in both directions\nsimilarly to the plane elastic media. The finite length crack assumes the shape\nof the elongated elliptic split. Another behavior of lattice occurs if the\nfibers, parallel to crack direction, are unstressed. The character of stress\nconcentration near the crack differs. The load distribution at the crack tip\nvaries considerably. The first unbroken fiber carries higher load. The crack is\nlens-shaped and the crack borders form at the tip the finite angle."
    },
    {
        "anchor": "Fluids of rod-like particles near curved surfaces: We study fluids of hard rods in the vicinity of hard spherical and\ncylindrical surfaces at densities below the isotropic-nematic transition. The\nOnsager second virial approximation is applied, which is known to yield exact\nresults for the bulk properties in the limit of infinitely thin rods. This\napproach requires the computation of the one-particle distribution function and\nof the Mayer function which is greatly facilitated by an appropriate expansion\nin terms of spherical harmonics. We determine density and orientational\nprofiles as well as the surface tension $\\gamma$ as function of the surface\ncurvature radius $R$. Already in the low-density limit of non-interacting rods\n$\\gamma(R)$ turns out to be non-analytic at $1/R=0$, which prohibits the\napplication of the commonly used Helfrich expansion. The interparticle\ninteraction modifies the behavior of $\\gamma(R)$ as compared to the low-density\nlimit quantitatively and qualitatively.",
        "positive": "Quasicrystalline three-dimensional foams: We present a numerical study of quasiperiodic foams, in which the bubbles are\ngenerated as duals of quasiperiodic Frank-Kasper phases. These foams are\ninvestigated as potential candidates to the celebrated Kelvin problem for the\npartition of three-dimensional space with equal volume bubbles and minimal\nsurface area. Interestingly, one of the computed structures falls close (but\nstill slightly above) the best known Weaire-Phelan periodic candidate. This\ngives additional clues to understanding the main geometrical ingredients\ndriving the Kelvin problem."
    },
    {
        "anchor": "X-ray Raman scattering study of aligned polyfluorene: We present a non-resonant inelastic x-ray scattering study at the carbon\nK-edge on aligned poly[9,9-bis(2-ethylhexyl)-fluorene-2,7-diyl] and show that\nthe x-ray Raman scattering technique can be used as a practical alternative to\nx-ray absorption measurements. We demonstrate that this novel method can be\napplied to studies on aligned $\\pi$-conjugated polymers complementing\ndiffraction and optical studies. Combining the experimental data and a very\nrecently proposed theoretical scheme we demonstrate a unique property of x-ray\nRaman scattering by performing the symmetry decomposition on the density of\nunoccupied electronic states into $s$- and $p$-type symmetry contributions.",
        "positive": "A new dipolar potential for numerical simulations of polar fluids on the\n  $4\\mathrm{D}$ hypersphere: We present a new method for Monte Carlo or Molecular Dynamics numerical\nsimulations of three dimensional polar fluids. The simulation cell is defined\nto be the surface of the northern hemisphere of a four-dimensional\n(hyper)sphere. The point dipoles are constrained to remain tangent to the\nsphere and their interactions are derived from the basic laws of electrostatics\nin this geometry. The dipole-dipole potential has two singularities which\ncorrespond to the following boundary conditions : when a dipole leaves the\nnorthern hemisphere at some point of the equator, it reappears at the antipodal\npoint bearing the same dipole moment. We derive all the formal expressions\nneeded to obtain the thermodynamic and structural properties of a polar liquid\nat thermal equilibrium in actual numerical simulation. We notably establish the\nexpression of the static dielectric constant of the fluid as well as the\nbehavior of the pair correlation at large distances. We report and discuss the\nresults of extensive numerical Monte Carlo simulations for two reference states\nof a fluid of dipolar hard spheres and compare these results with previous\nmethods with a special emphasis on finite size effects."
    },
    {
        "anchor": "Nonlinear dynamic analysis of an optimal particle damper: We study the dynamical behavior of a single degree of freedom mechanical\nsystem with a particle damper. The particle (granular) damping was optimized\nfor the primary system operating condition by using an appropriate gap size for\na prismatic enclosure. The particles absorb the kinetic energy of the vibrating\nstructure and convert it into heat through the inelastic collisions and\nfriction. This results in a highly nonlinear mechanical system. Considering\nlinear signal analysis, state space reconstruction, Poincar\\'e sections and the\ndetermination of maximal Lyapunov exponents, the motion of the granular system\ninside the enclosure is characterized for a wide frequency range. With the\nexcitation frequency as control parameter, either regular and chaotic motion of\nthe granular bed are found and their influence on the damping is analyzed.",
        "positive": "The cytoplasm of living cells: A functional mixture of thousands of\n  components: Inside every living cell is the cytoplasm: a fluid mixture of thousands of\ndifferent macromolecules, predominantly proteins. This mixture is where most of\nthe biochemistry occurs that enables living cells to function, and it is\nperhaps the most complex liquid on earth. Here we take an inventory of what is\nactually in this mixture. Recent genome-sequencing work has given us for the\nfirst time at least some information on all of these thousands of components.\nHaving done so we consider two physical phenomena in the cytoplasm: diffusion\nand possible phase separation. Diffusion is slower in the highly crowded\ncytoplasm than in dilute solution. Reasonable estimates of this slowdown can be\nobtained and their consequences explored, for example, monomer-dimer equilibria\nare established approximately twenty times slower than in a dilute solution.\nPhase separation in all except exceptional cells appears not to be a problem,\ndespite the high density and so strong protein-protein interactions present. We\nsuggest that this may be partially a byproduct of the evolution of other\nproperties, and partially a result of the huge number of components present."
    },
    {
        "anchor": "Bistable director alignments of nematic liquid crystals confined in\n  frustrated substrates: We studied in-plane bistable alignments of nematic liquid crystals confined\nby two frustrated surfaces by means of Monte Carlo simulations of the\nLebwohl-Lasher spin model. The surfaces are prepared with orientational\ncheckerboard patterns, on which the director field is locally anchored to be\nplanar yet orthogonal between the neighboring blocks. We found the director\nfield in the bulk tends to be aligned along the diagonal axes of the\ncheckerboard pattern, as reported experimentally [J.-H. Kim et al., Appl. Phys.\nLett. 78, 3055 (2001)]. The energy barrier between the two stable orientations\nis increased, when the system is brought to the isotropic-nematic transition\ntemperature. Based on an elastic theory, we found that the bistability is\nattributed to the spatial modulation of the director field near the frustrated\nsurfaces. As the block size is increased and/or the elastic modulus is reduced,\nthe degree of the director inhomogeneity is increased, enlarging the energy\nbarrier. We also found that the switching rate between the stable states is\ndecreased when the block size is comparable to the cell thickness.",
        "positive": "Force Distributions in Frictional Granular Media: We report a joint experimental and theoretical investigation of the\nprobability distribution functions (pdf's) of the normal and tangential\n(frictional) forces in amorphous frictional media. We consider both the joint\npdf of normal and tangential forces together, and the marginal pdf's of normal\nforces separately and tangential forces separately. A maximum entropy formalism\nis utilized for all these cases after identifying the appropriate constraints.\nExcellent agreements with both experimental and simulational data are reported.\nThe proposed joint pdf (which appears new to the literature) predicts giant\nslip events at low pressures, again in agreement with observations."
    },
    {
        "anchor": "Charging of Heated Colloidal Particles Using the Electrolyte Seebeck\n  Effect: We propose a novel actuation mechanism for colloids, which is based on the\nSeebeck effect of the electrolyte solution: Laser heating of a nonionic\nparticle accumulates in its vicinity a net charge Q, which is proportional to\nthe excess temperature at the particle surface. The corresponding long-range\nthermoelectric field provides a tool for controlled interactions with nearby\nbeads or with additional molecular solutes. An external field Eext drags the\nthermocharged particle at a velocity that depends on its size and absorption\nproperties; the latter point could be particularly relevant for separating\ncarbon nanotubes according to their electronic band structure.",
        "positive": "Demixing of active particles in the presence of external fields: Active systems are inherently out of equilibrium, as they collect energy from\ntheir surroundings and transform it into directed motion. A recent theoretical\nstudy suggests that binary mixtures of active particles with distinct effective\ndiffusion coefficients exhibit dynamical demixing above a threshold ratio of\nthe diffusion coefficients. Here, we show that this threshold may be reduced\ndrastically in the presence of external fields. We investigate the demixing as\na function of the ratio of the diffusion coefficients and discuss the\nimplications of the results for active systems."
    },
    {
        "anchor": "Modeling of polymer-enzyme conjugates formation: Thermodynamic\n  perturbation theory and computer simulations: A simple model for the formation of the polymer-enzyme conjugates has been\nproposed and described using corresponding extension of the Wertheim's\nfirst-order thermodynamic perturbation theory (TPT1) for the system of\nassociating chain molecules. A set of computer simulation data for different\nnumber of functional groups along polymer chains has been obtained and used to\naccess the accuracy of the theoretical results. Predictions of the present\ntheoretical approach are more accurate than that of the conventional TPT1 and\nare in a very good agreement with the computer simulation data. In particular\nthe theory is able to account for the difference in position of the polymer\nfunctional groups along its backbone.",
        "positive": "Nonergodicity transitions in colloidal suspensions with attractive\n  interactions: The colloidal gel and glass transitions are investigated using the idealized\nmode coupling theory (MCT) for model systems characterized by short-range\nattractive interactions. Results are presented for the adhesive hard sphere and\nhard core attractive Yukawa systems. According to MCT, the former system shows\na critical glass transition concentration that increases significantly with\nintroduction of a weak attraction. For the latter attractive Yukawa system, MCT\npredicts low temperature nonergodic states that extend to the critical and\nsubcritical region. Several features of the MCT nonergodicity transition in\nthis system agree qualitatively with experimental observations on the colloidal\ngel transition, suggesting that the gel transition is caused by a low\ntemperature extension of the glass transition. The range of the attraction is\nshown to govern the way the glass transition line traverses the phase diagram\nrelative to the critical point, analogous to findings for the fluid-solid\nfreezing transition."
    },
    {
        "anchor": "Collective Hall current in chiral active fluids: Coupling of phase and\n  mass transport through traveling bands: Active fluids composed of constituents that are constantly driven away from\nthermal equilibrium can support spontaneous currents and can be engineered to\nhave unconventional transport properties. Here we report the emergence of\n(meta-)stable traveling bands in computer simulations of aligning circle\nswimmers. These bands are different from polar flocks and we show that they can\nbe understood as non-dispersive soliton solutions of the underlying non-linear\nhydrodynamic equations with constant celerity (phase propagation speed) that is\nmuch larger than the propulsion speed. In contrast to solitons in passive\nmedia, these bands can induce a bulk particle current with a component\nperpendicular to the propagation direction, thus constituting a collective Hall\n(or Magnus) effect. Traveling bands require sufficiently small orbits and\nundergo a discontinuous transition into a synchronized state with transient\npolar clusters for large orbital radii.",
        "positive": "Droplet detachment and pinch-off of bidisperse particulate suspensions: When a droplet is generated, the ligament connecting the drop to the nozzle\nthins down and eventually pinches off. Adding solid particles to the liquid\nphase leads to a more complex dynamic, notably by increasing the shear\nviscosity. Moreover, it introduces an additional length scale to the system,\nthe diameter of the particles, which eventually becomes comparable to the\ndiameter of the ligament. In this paper, we experimentally investigate the\nthinning and pinch-off of drops of suspensions with two different sizes of\nparticles. We characterize the thinning for different particle size ratios and\ndifferent proportions of small particles. Long before the pinch-off, the\nthinning rate is that of an equivalent liquid whose viscosity is that of the\nsuspension. Later, when the ligament thickness approaches the size of the large\nparticles, the thinning accelerates and leads to an early pinch-off. We explain\nhow the bidisperse particle size distribution lowers the viscosity by making\nthe packing more efficient, which speeds up the thinning. This result can be\nused to predict the dynamics of droplet formation with bidisperse suspensions."
    },
    {
        "anchor": "Self-assembly of artificial microtubules: Understanding the complex self-assembly of biomacromolecules is a major\noutstanding question. Microtubules are one example of a biopolymer that\npossesses characteristics quite distinct from standard synthetic polymers that\nare derived from its hierarchical structure. In order to understand how to\ndesign and build artificial polymers that possess features similar to those of\nmicrotubules, we have initially studied the self-assembly of model monomers\ninto a tubule geometry. Our model monomer has a wedge shape with lateral and\nvertical binding sites that are designed to form tubules. We used molecular\ndynamics simulations to study the assembly process for a range of binding site\ninteraction strengths. In addition to determining the optimal regime for\nobtaining tubules, we have calculated a diagram of the structures that form\nover a wide range of interaction strengths. Unexpectedly, we find that the\nhelical tubules form, even though the monomer geometry is designed for\nnonhelical tubules. We present the detailed dynamics of the tubule\nself-assembly process and show that the interaction strengths must be in a\nlimited range to allow rearrangement within clusters. We extended previous\ntheoretical methods to treat our system and to calculate the boundaries between\ndifferent structures in the diagram.",
        "positive": "Surface properties of liquid mercury: a comparison of density-dependent\n  and density-independent force fields: Motivated by an experimental interest we investigate by the means of\natomistic Molecular Dynamics simulation the ability of density-independent,\nempiric density-dependent, and recently proposed embedded-atom force fields for\nliquid mercury to predict the surface tension of the free surface of liquid\nmercury at the temperature of 293~K. The effect of the density dependence of\nthe studied models on the liquid-vapor coexistence and surface tension is\ndiscussed in detail. In view of computational efficiency of the\ndensity-independent model we optimize its functional form to obtain higher\nsurface tension values in order to improve agreement with experiment. The\nresults are also corroborated by Monte Carlo simulations and semi-analytic\nestimations of the liquid-vapor coexistence density."
    },
    {
        "anchor": "Exploring canyons in glassy energy landscapes using metadynamics: The complex physics of glass forming systems is controlled by the structure\nof the low energy portions of their potential energy landscapes. Here, we\nreport that a modified metadynamics algorithm efficiently explores and samples\nlow energy regions of such high-dimensional landscapes. In the energy landscape\nfor a model foam, our algorithm finds and descends meandering `canyons' in the\nlandscape, which contain dense clusters of energy minima along their floors.\nSimilar canyon structures in the energy landscapes of two model glass formers\n-- hard sphere fluids and the Kob-Andersen glass -- allow us to reach high\ndensities and low energies, respectively. In the hard sphere system, fluid\nconfigurations are found to form continuous regions that cover the canyon\nfloors up to densities well above the jamming transition. For the Kob-Andersen\nglass former, our technique samples low energy states with modest computational\neffort, with the lowest energies found approaching the predicted Kauzmann\nlimit.",
        "positive": "Topological generalization of the rigid-nonrigid transition in\n  soft-sphere and hard-sphere fluids: A fluid particle changes its dynamics from diffusive to oscillatory as the\nsystem density increases up to the melting density. Hence, the notion of the\nFrenkel line was introduced to demarcate the fluid region into rigid and\nnonrigid liquid subregions based on the collective particle dynamics. In this\nwork, we apply a topological framework to locate the Frenkel lines of the\nsoft-sphere and the hard-sphere models relying on the system configurations.\nThe topological characteristics of the ideal gas and the maximally random\njammed state are first analyzed, then the classification scheme designed in our\nearlier work is applied. The classification result shows that the fraction of\nsolid-like atoms increases from zero to one in the rigid liquid region. The\ndependence of the solid-like fraction on the bulk density is understood based\non the theory of fluid polyamorphism. The percolation behavior of solid-like\nclusters is described based on the fraction of solid-like molecules in an\nintegrated manner. The crossover densities are obtained by examining the\npercolation of solid-like clusters. The resultant crossover densities of\nsoft-sphere fluids converge to that of hard-sphere fluid. Hence, the\ntopological method successfully highlights the generality of the Frenkel line."
    },
    {
        "anchor": "Enhancing tracer diffusivity by tuning interparticle interactions and\n  coordination shell structure: This study uses a combination of stochastic optimization, statistical\nmechanical theory, and molecular simulation to test the extent to which the\nlong-time dynamics of a single tracer particle can be enhanced by rationally\nmodifying its interactions--and hence static correlations--with the other\nparticles of a dense fluid. Specifically, a simulated annealing strategy is\nintroduced that, when coupled with test-particle calculations from an accurate\ndensity functional theory, finds interactions that maximize either the tracer's\npartial molar excess entropy or a related pair-correlation measure (i.e., two\nquantities known to correlate with tracer diffusivity in other contexts). The\noptimized interactions have soft, Yukawa-like repulsions, which extend beyond\nthe hard-sphere interaction and disrupt the coordination-shell cage structure\nsurrounding the tracer. Molecular and Brownian dynamics simulations find that\ntracers with these additional soft repulsions can diffuse more than three times\nfaster than bare hard spheres in a moderately supercooled fluid, despite the\nfact that the former appear considerably larger than the latter by conventional\ndefinitions of particle size.",
        "positive": "Cluster pair correlation function of simple fluids: energetic\n  connectivity criteria: We consider the clustering of Lennard-Jones particles by using an energetic\nconnectivity criterion proposed long ago by T.L. Hill [J. Chem. Phys. 32, 617\n(1955)] for the bond between pairs of particles. The criterion establishes that\ntwo particles are bonded (directly connected) if their relative kinetic energy\nis less than minus their relative potential energy. Thus, in general, it\ndepends on the direction as well as on the magnitude of the velocities and\npositions of the particles. An integral equation for the pair connectedness\nfunction, proposed by two of the authors [Phys Rev. E 61, R6067 (2000)], is\nsolved for this criterion and the results are compared with those obtained from\nmolecular dynamics simulations and from a connectedness Percus-Yevick like\nintegral equation for a velocity-averaged version of Hill's energetic\ncriterion."
    },
    {
        "anchor": "Dynamic Coarse-Graining of Linear and Non-Linear Systems: Mori-Zwanzig\n  Formalism and Beyond: To investigate the impact of non-linear interactions on dynamic coarse\ngraining, we study a simplified model system, featuring a tracer particle in a\ncomplex environment. Using a projection operator formalism and computer\nsimulations, we systematically derive generalized Langevin equations describing\nthe dynamics of this particle. We compare different kinds of linear and\nnon-linear coarse-graining procedures to understand how non-linearities enter\nreconstructed generalized Langevin equations and how they influence the\ncoarse-grained dynamics. For non-linear external potentials, we show\nanalytically and numerically that the non-Gaussian parameter and the incoherent\nintermediate scattering function will not be correctly reproduced by the\ngeneralized Langevin equation if a linear projection is applied. This, however,\ncan be overcome by using non-linear projection operators. We also study\nanharmonic coupling between the tracer and the environment and demonstrate that\nthe reconstructed memory kernel develops an additional trap-dependent\ncontribution. Our study highlights some open challenges and possible solutions\nin dynamic coarse graining.",
        "positive": "Mesoscale simulations of polymer dynamics in microchannel flows: The non-equilibrium structural and dynamical properties of flexible polymers\nconfined in a square microchannel and exposed to a Poiseuille flow are\ninvestigated by mesoscale simulations. The chain length and the flow strength\nare systematically varied. Two transport regimes are identified, corresponding\nto weak and strong confinement. For strong confinement, the transport\nproperties are independent of polymer length. The analysis of the long-time\ntumbling dynamics of short polymers yields non-periodic motion with a sublinear\ndependence on the flow strength. We find distinct differences for\nconformational as well as dynamical properties from results obtained for simple\nshear flow."
    },
    {
        "anchor": "The model of the ideal crystal as a criterion for evaluating of the\n  approximate equations of the liquids: It is necessary for the statistical description of collective effects in\nliquids to set that or other approximation between direct and pair correlation\nfunctions which describe a neighboring order. The analytical solution of the\ngeneralized Ornstein-Zernike (OZ) equation was obtained for a system of\nparticles at T=0. It is shown that in this limit case the neighboring order\ndisappears and the direct correlation function describes a distant order which\nis typical for the ideal crystal. The approximation correctly describing the\nlimit transition liquid-solid at T=0 will have a physical meaning.",
        "positive": "Alternating strings and clusters in suspensions of charged colloids: We report the formation of alternating strings and clusters in a binary\nsuspension of repulsive charged colloids with double layers larger than the\nparticle size. Within a binary cell model we include many-body and\ncharge-regulation effects under the assumption of a constant surface potential,\nand consider their repercussions on the two-particle interaction potential. We\nfind that the formation of induced dipoles close to a charge-reversed state may\nexplain the formation of these structures. Finally, we will touch upon the\nformation of dumbbells and small clusters in a one-component system, where the\neffective electrostatic interaction is always repulsive."
    },
    {
        "anchor": "Phase Diagram of Amorphous Solid Water: Low-Density, High-Density, and\n  Very-High-Density Amorphous Ices: We describe the phase diagram of amorphous solid water by performing\nmolecular dynamics simulations. Our simulations follow different paths in the\nphase diagram: isothermal compression/decompression, isochoric cooling/heating\nand isobaric cooling/heating. We are able to identify low-density amorphous\n(LDA), high-density amorphous (HDA), and very-high density amorphous (VHDA)\nices. The density $\\rho$ of these glasses at different pressure $P$ and\ntemperature $T$ agree well with experimental values. We also study the radial\ndistribution functions of glassy water. We obtain VHDA by isobaric heating of\nHDA, as in experiment. We also find that ``other forms'' of glassy water can be\nobtained upon isobaric heating of LDA, as well as amorphous ices formed during\nthe transformation of LDA to HDA. We argue that these other forms of amorphous\nices, as well as VHDA, are not altogether new glasses but rather are the result\nof aging induced by heating. Samples of HDA and VHDA with different densities\nare recovered at normal $P$, showing that there is a continuum of glasses.\nFurthermore, the two ranges of densities of recovered HDA and recovered VHDA\noverlap at ambient $P$. Our simulations are consistent with the possibility of\nHDA$\\to$LDA and VHDA$\\to$LDA transformations, reproducing the experimental\nfindings. We do not observe a VHDA$\\to$HDA transformation.",
        "positive": "Effects of liquid fraction and contact angle on structure and coarsening\n  in two-dimensional foams: Aqueous foams coarsen with time due to gas diffusion through the liquid. The\nmean bubble size grows, and small bubbles vanish. However, coarsening is little\nunderstood for foams with an intermediate liquid content, particularly in the\npresence of surfactant-induced attractive forces between the bubbles, measured\nby the contact angle. Rigorous bubble growth laws have yet to be developed, and\nthe evolution of bulk foam properties is unclear. We present a quasi-static\nnumerical model for coarsening in two-dimensional wet foams, focusing on growth\nlaws and related bubble properties. The deformation of bubbles is modelled\nusing a finite-element approach, and the gas flow through both films and\nPlateau borders is approximated. We give results for disordered two-dimensional\nwet foams with 256 to 1024 bubbles, at liquid fractions from $2\\%$ to beyond\nthe zero-contact-angle jamming transition, and with contact angles up to\n$10^\\circ$. Simple analytical models are developed to aid interpretation. We\nfind that nonzero contact angle causes a proxy of the initial coarsening rate\nto plateau at large liquid fractions, and that the individual bubble growth\nrates are closely related to their effective number of neighbours."
    },
    {
        "anchor": "Cascade Freezing of Supercooled Water Droplet Collectives: Surface icing affects the safety and performance of numerous processes in\ntechnology. Previous studies mostly investigated freezing of individual\ndroplets. The interaction among multiple droplets during freezing is\ninvestigated less, especially on nanotextured icephobic surfaces, despite its\npractical importance as water droplets never appear in isolation, but in\ngroups. Here we show that freezing of a supercooled droplet leads to\nspontaneous self-heating and induces strong vaporization. The resulting,\nrapidly propagating vapor front causes immediate cascading freezing of\nneighboring supercooled droplets upon reaching them. We put forth the\nexplanation that, as the vapor approaches cold neighboring droplets, it can\nlead to local supersaturation and formation of airborne microscopic ice\ncrystals, which act as freezing nucleation sites. The sequential triggering and\npropagation of this mechanism results in the rapid freezing of an entire\ndroplet ensemble resulting in ice coverage of the nanotextured surface.\nAlthough cascade freezing is observed in a low-pressure environment, it\nintroduces an unexpected pathway of freezing propagation that can be crucial\nfor the performance of rationally designed icephobic surfaces.",
        "positive": "Stability of multi-lamellar lipid tubules in excess water: In the lyotropic phase of lipids with excess water, multilamellar tubules\n(MLTs) grow from defects. A phenomenological model for the stability of MLTs is\ndeveloped that is universal and independent of the underlying growth mechanisms\nof MLTs. The stability of MLTs implies that they are in hydrostatic equilibrium\nand stable as elastic objects that have compression and bending elasticity. The\nresults show that even with 0.1 atm solvent pressure differences, the density\nprofile is not significantly altered, thus determining that the stability is\ndue to the trapped solvent. The results are of sufficient value in relation to\nlamellar stability models and may have implications beyond the described MLT\nmodels, especially in other models of membrane systems."
    },
    {
        "anchor": "Diffusion of single active-dipolar cubes in applied fields: \"Active matter\" refers to a class of out-of-equilibrium systems whose ability\nto transform environmental energy to kinetic energy is sought after in multiple\nfields of science and at very different length scales. At microscopic scales,\nan important challenge lies in overpowering the particles reorientation due to\nthermal fluctuations, especially in nano-sized systems, to create non-random,\ndirected motion, needed for a wide range of possible applications. In this\narticle, we employ molecular dynamics simulations to show that the diffusion of\na self-propelling dipolar nanocube can be enhanced in a pre-defined direction\nwith the help of a moderately strong applied magnetic field, overruling the\neffect of the thermal fluctuations. Furthermore, we show that the direction of\ndiffusion is given by the orientation of the net internal magnetisation of the\ncube. This can be used to determine experimentally the latter in synthetically\ncrafted active cobalt ferrite nanocubes.",
        "positive": "Lattice Boltzmann simulations of liquid crystalline fluids: active gels\n  and blue phases: Lattice Boltzmann simulations have become a method of choice to solve the\nhydrodynamic equations of motion of a number of complex fluids. Here we review\nsome recent applications of lattice Boltzmann to study the hydrodynamics of\nliquid crystalline materials. In particular, we focus on the study of (a) the\nexotic blue phases of cholesteric liquid crystals, and (b) active gels - a\nmodel system for actin plus myosin solutions or bacterial suspensions. In both\ncases lattice Boltzmann studies have proved useful to provide new insights into\nthese complex materials."
    },
    {
        "anchor": "Integration through transients approach to the $\u03bc(\\mathcal{I})$\n  rheology: This work generalises the granular integration through transients formalism\nintroduced by Kranz et al. [Phys. Rev. Lett. 121, 148002 (2018)] to the\ndetermination of the pressure. We focus on the Bagnold regime, and provide\ntheoretical support to the empirical $\\mu(\\mathcal{I})$ rheology laws, that\nhave been successfully applied in many granular flow problems. In particular,\nwe confirm that the interparticle friction is irrelevant in the regime where\nthe $\\mu(\\mathcal{I})$ laws apply.",
        "positive": "Vapor-Induced Motion of Liquid Droplets on an Inert Substrate: Evaporating droplets are known to show complex motion that has conventionally\nbeen explained by the Marangoni effect (flow induced by the gradient of surface\ntension). Here, we show that the droplet motion can be induced even in the\nabsence of the Marangoni effect due to the gradient of evaporation rate. We\nderive an equation for the velocity of a droplet subject to non-uniform\nevaporation rate and non-uniform surface tension placed on an inert substrate\nwhere the wettability is uniform and unchanged. The equation explains the\npreviously observed attraction-repulsion- chasing behaviors of evaporating\ndroplets."
    },
    {
        "anchor": "Challenges in the rheology of glasses: In this contribution to the proceedings of the 29th Solvay Conference on\nPhysics I will give an overview of some key challenges in our theoretical\nunderstanding of the rheology of glasses, focussing on (i) steady shear flow\ncurves and their relation to the glass and jamming transitions, (ii) ductile\nversus brittle yielding in shear startup and (iii) yielding under oscillatory\nshear. I will also briefly discuss connections to the reversible-irreversible\nand random organization transitions as well as to the broad field of memory\nformation in materials.",
        "positive": "Structure and position-dependent properties of inhomogeneous suspensions\n  of responsive colloids: Responsive particles, such as biomacromolecules or hydrogels, display a broad\nand polymodal distribution of conformations and have thus the ability to change\ntheir properties (e.g, size, shape, charge density, etc.) substantially in\nresponse to external fields or to their local environment (e.g., mediated by\ncosolutes or pH). Here, we discuss the basic statistical mechanics for a model\nof responsive colloids (RCs) by introducing an additional property degree of\nfreedom as a collective variable in a formal coarse-graining procedure. The\nlatter leads to an additional one-body term in the coarse-grained (CG) free\nenergy, defining a single-particle property distribution for an individual\npolydisperse RC. We argue that in the equilibrium thermodynamic limit such a CG\nsystem of RCs behaves like a conventional polydisperse system of non-responsive\nparticles. We then illustrate the action of external fields, which impose local\n(position-dependent) property distributions leading to non-trivial effects on\nthe spatial one-body property and density profiles, even for an ideal\n(non-interacting) gas of RCs. We finally apply density functional theory in the\nlocal density approximation (LDA-DFT) to discuss the effects of particle\ninteractions for specific examples of i) a suspension of RCs in an external\nfield linear in both position and property, ii) a suspension of RCs with highly\nlocalized properties (sizes) confined between two walls, and iii) a\ntwo-component suspension where an inhomogeneously distributed (non-responsive)\ncosolute component, as found, e.g., in the studies of osmolyte- or salt-induced\ncollapse/swelling transitions of thermosensitive polymers, modifies the local\nproperties and density of the RC liquid."
    },
    {
        "anchor": "Driving kinetically constrained models into non-equilibrium steady\n  states: structural and slow transport properties: Complex fluids in shear flow and biased dynamics in crowded environments\nexhibit counterintuitive features which are difficult to address both at\ntheoretical level and by molecular dynamic simulations. To understand some of\nthese features we study a schematic model of highly viscous liquid, the 2D\nKob-Andersen kinetically constrained model, driven into non-equilibrium steady\nstates by a uniform non-Hamiltonian force. We present a detailed numerical\nanalysis of the microscopic behavior of the model, including transversal and\nlongitudinal spatial correlations and dynamic heterogeneities. In particular,\nwe show that at high particle density the transition from positive to negative\nresistance regimes in the current vs field relation can be explained via the\nemergence of nontrivial structures that intermittently trap the particles and\nslow down the dynamics. We relate such spatial structures to the current vs\nfield relation in the different transport regimes.",
        "positive": "Self-Affine Elastic Contacts: Percolation and Leakage: We study fluid flow at the interfaces between elastic solids with randomly\nrough, self-affine surfaces. We show by numerical simulation that elastic\ndeformation lowers the relative contact area at which contact patches percolate\nin comparison to traditional approaches to seals. Elastic deformation also\nsuppresses leakage through contacts even far away from the percolation\nthreshold. Reliable estimates for leakage can be obtained by combining\nPersson's contact mechanics theory with a slightly modified version of\nBruggeman's effective-medium solution of the Reynolds equation."
    },
    {
        "anchor": "A flexible rheometer design to measure the visco-elastic response of\n  soft solids over a wide range of frequency: We present a flexible set-up for determining the rheology of visco-elastic\nmaterials which is based on the mechanical response of a magnet deposited at\nthe surface of a slab of material and excited electromagnetically. An\ninterferometric measurement of the magnet displacement allows one to reach an\nexcellent accuracy over a wide range of frequency. Except for the magnet, there\nis no contact between the material under investigation and the apparatus. At\nlow frequency, inertial effects are negligible so that the mechanical response,\nobtained through a lock-in amplifier, directly gives the material complex\nmodulus. At high frequency, damped waves are emitted and the rheology must be\nextracted numerically from a theoretical model. To validate the design, the\ninstrument was used to measure the rheology of a test PDMS gel which presents\nan almost perfect scale free response at high frequency.",
        "positive": "Onset of self-assembly: We have developed a theory of polymer entanglement using an extended\nCahn-Hilliard functional, with two extra terms. One is a nonlocal attractive\nterm, operating over mesoscales, which is interpreted as giving rise to\nentanglement, and the other a local repulsive term indicative of excluded\nvolume interactions. This functional can be derived using notions from gauge\ntheory. We go beyond the Gaussian approximation, to the one-loop level, to show\nthat the system exhibits a crossover to a state of entanglement as the average\nchain length between points of entanglement decreases. This crossover is marked\nby critical slowing down, as the effective diffusion constant goes to zero. We\nhave also computed the tensile modulus of the system, and we find a\ncorresponding crossover to a regime of high modulus. The single parameter in\nour theory is obtained by fitting to available experimental data on polystyrene\nmelts of various chain lengths. Extrapolation of this fit yields a model for\nthe cross-over to entanglement. The need for additional experiments detailing\nthe cross-over to the entangled state is pointed out."
    },
    {
        "anchor": "General weak segregation theory with an application to monodisperse\n  semi-flexible diblock copolymers: A general theory has been developed for a polydisperse semi-flexible\nmulti-block copolymer melt. Using the Bawendi-Freed approach to model\nsemi-flexible chains an expression for the Landau free energy is derived in the\nweak segregation regime which includes the density and orientation\norder-parameters. The orientation order-parameter is described in the smectic\nphase and in more complicated structures such as the hexagonal phase. The\nLandau free energy contains contributions of two kinds of interactions. The\nfirst kind is the Flory- Huggins interaction which describes the\nincompatibility of chemically different blocks and may induce microphase\nseparation. The second kind is the Maier- Saupe interaction which may induce\nnematic ordening. In the framework of the weak segragation limit the Landau\ntheory allows to predict phase structures in the melt as a function of the\ncomposition, persistence length and the strength of the Flory-Huggins and\nMaier-Saupe interaction. The general theory is applied to a simple system of\nmonodisperse semi-flexible diblock copolymers. In several phase diagrams a\nnumber of possible phase structures is predicted such as the bcc, hexagonal,\nsmectic-A, smectic-C and nematic phase. The infuence of the Maier-Saupe\ninteraction on the microphase structure is thoroughly discussed.",
        "positive": "Interplay of gross and fine structures in strongly-curved sheets: Although thin films are typically manufactured in planar sheets or rolls,\nthey are often forced into three-dimensional shapes, producing a plethora of\nstructures across multiple length-scales. Existing theoretical approaches have\nmade progress by separating the behaviors at different scales and limiting\ntheir scope to one. Under large confinement, a geometric model has been\nproposed to predict the gross shape of the sheet, which averages out the fine\nfeatures. However, the actual meaning of the gross shape, and how it constrains\nthe fine features, remains unclear. Here, we study a thin-membraned balloon as\na prototypical system that involves a doubly curved gross shape with large\namplitude undulations. By probing its profiles and cross sections, we discover\nthat the geometric model captures the mean behavior of the film. We then\npropose a minimal model for the balloon cross sections, as independent elastic\nfilaments subjected to an effective pinning potential around the mean shape.\nThis approach allows us to combine the global and local features consistently.\nDespite the simplicity of our model, it reproduces a broad range of phenomena\nseen in the experiments, from how the morphology changes with pressure to the\ndetailed shape of the wrinkles and folds. Our results establish a new route to\nunderstanding finite buckled structures over an enclosed surface, which could\naid the design of inflatable structures, or provide insight into biological\npatterns."
    },
    {
        "anchor": "Influence of Pressure on Smectic A-Nematic Phase Transition: We propose a Landau-de Gennes phenomenological model to describe the pressure\ninduced smectic A-nematic phase transition. The pressure induced smectic A\nphase transitions are discussed for varying coupling between orientational and\ntranslational order parameter. Increasing the pressure, the first order\nnematic-smectic A transition becomes second order at a tricritical point which\nagrees fairly with available experimental results.",
        "positive": "Comparative study of force-based classical density functional theory: We reexamine results obtained with the recently proposed density functional\ntheory framework based on forces (force-DFT) [Tschopp et al., Phys. Rev. E 106,\n014115 (2022)]. We compare inhomogeneous density profiles for hard sphere\nfluids to results from both standard density functional theory and from\ncomputer simulations. Test situations include the equilibrium hard sphere fluid\nadsorbed against a planar hard wall and the dynamical relaxation of hard\nspheres in a switched harmonic potential. The comparison to grand canonical\nMonte Carlo simulation profiles shows that equilibrium force-DFT alone does not\nimprove upon results obtained with the standard Rosenfeld functional. Similar\nbehavior holds for the relaxation dynamics, where we use our event-driven\nBrownian dynamics data as benchmark. Based on an appropriate linear combination\nof standard and force-DFT results, we investigate a simple hybrid scheme which\nrectifies these deficiencies in both the equilibrium and the dynamical case. We\nexplicitly demonstrate that although the hybrid method is based on the original\nRosenfeld fundamental measure functional, its performance is comparable to that\nof the more advanced White Bear theory."
    },
    {
        "anchor": "Pacman Percolation and the Glass Transition: We investigate via Monte Carlo simulations the kinetically constrained\nKob-Andersen lattice glass model showing that, contrary to current\nexpectations, the relaxation process and the dynamical heterogeneities seems to\nbe characterized by different time scales. Indeed, we found that the relaxation\ntime is related to a reverse percolation transition, whereas the time of\nmaximum heterogeneity is related to the spatial correlation between particles.\nThis investigation leads to a geometrical interpretation of the relaxation\nprocesses and of the different observed time scales.",
        "positive": "Local viscoelasticity of living cells measured by rotational magnetic\n  spectroscopy: When submitted to a magnetic field, micron size wires with superparamagnetic\nproperties behave as embedded rheometers and represent interesting sensors for\nmicro-rheology. Here we use rotational magnetic spectroscopy to measure the\nshear viscosity of the cytoplasm of living cells. We address the question of\nwhether the cytoplasm is a viscoelastic liquid or a gel. The main result of the\nstudy is the observation of a rotational instability between a synchronous and\nan asynchronous regime of rotation, found for murine fibroblasts and human\ncancer cells. For wires of susceptibility 3.6, the transition occurs in the\nrange 0.01...1 rad s-1. The determination of the shear viscosity (10...100 Pa\ns) and elastic modulus (5...20 Pa) confirms the viscoelastic character of the\ncytoplasm. In contrast to earlier studies, it is concluded that the interior of\nliving cells can be described as a viscoelastic liquid, and not as an elastic\ngel."
    },
    {
        "anchor": "Pattern transitions in a compressible floating elastic sheet: Thin rigid sheets floating on a liquid substrate appear, for example, in\ncoatings and surfactant monolayers. Upon uniaxial compression the sheet\nundergoes transitions from a compressed flat state to a periodic wrinkled\npattern to a localized folded pattern. The stability of these states is\ndetermined by the in-plane elasticity of the sheet, its bending rigidity, and\nthe hydrostatics of the underlying liquid. Wrinkles and folds, and the\nwrinkle-to-fold transition, were previously studied for incompressible sheets.\nIn the present work we extend the theory to include finite compressibility. We\nanalyze the details of the flat-to-wrinkle transition, the effects of\ncompressibility on wrinkling and folding, and the compression field associated\nwith the pattern formation. The state diagram of the floating sheet including\nall three states is presented.",
        "positive": "Algebraic equations of state for the liquid crystalline phase behavior\n  of hard rods: Based on simplifications of previous numerical calculations [Graf and\nL\\\"{o}wen, Phys. Rev. E \\textbf{59}, 1932 (1999)], we propose algebraic free\nenergy expressions for the smectic-A liquid crystal phase and the crystal\nphases of hard spherocylinders. Quantitative agreement with simulations is\nfound for the resulting equations of state. The free energy expressions can be\nused to straightforwardly compute the full phase behavior for all aspect ratios\nand to provide a suitable benchmark for exploring how attractive interrod\ninteractions mediate the phase stability through perturbation approaches such\nas free-volume or van der Waals theory."
    },
    {
        "anchor": "Stability of Magnetically Trapped Bose-Einstein Condensates: According to the adiabatic approximation atoms moving in a magnetic trap keep\ntheir magnetic states. We investigate the validity of this approximation for\nquantum condensates, where a change of field's direction generates effective\ninteractions between hyperfine angular momentum states. Condensates in general\ntraps are found to be stable because they are confined in the vicinity of the\ntrap center. A decay of a condensate is observable in a trap with extremely\nlarge field gradient.",
        "positive": "Crack formation in wet colloidal pillars: We investigate the initiation of cracks in vertically freestanding\nwater-saturated colloidal pillars constructed using a direct-write technique.\nParadoxically, the cracks form during drying at the free end, far from the\nsubstrate, where the particle network is unconstrained in contracting its\nvolume as it bears compression by a uniform capillary pressure acting at its\nouter surface. This is explained by a dominant balance of wetting energy terms,\nfrom which follows a simple relationship between the particle size and pillar\ndimensions that captures the presence or absence of cracks. This relationship\nprovides a practical guideline for fabricating crack-free colloidal structures."
    },
    {
        "anchor": "Adsorption and grafting on colloidal interfaces studied by scattering\n  techniques: The adsorption of polymer and surfactant molecules onto colloidal particles\nor droplets in solution can be characterized non-destructively by scattering\ntechniques. In a first part, the general framework of Dynamic Light Scattering,\nSmall Angle Neutron and X-ray Scattering for the determination of the structure\nof adsorbed layers, and namely of the density profile, is presented. We then\nreview recent studies of layers of the model polymer poly(ethylene oxide), as\nhomopolymer or part of a block copolymer. In this field, scattering with\ncontrast variation has been shown to be a powerful tool to obtain a detailed\ndescription of the layer structure. Adsorption of chemically more complex\nsystems, including polyelectrolytes, polymer complexes, grafted chains and\nbiomacromolecules are also discussed in this review, as well as surfactant\nadsorption.",
        "positive": "Predicting the mechanical properties of spring networks: The elastic response of mechanical, chemical, and biological systems is often\nmodeled using a discrete arrangement of Hookean springs, either representing\nfinite material elements or even the molecular bonds of a system. However, to\ndate, there is no direct derivation of the relation between a general discrete\nspring network and it's corresponding elastic continuum. Furthermore,\nunderstanding the network's mechanical response requires simulations that may\nbe expensive computationally. Here we report a method to derive the exact\nelastic continuum model of any discrete network of springs, requiring network\ngeometry and topology only. We identify and calculate the so-called\n\"non-affine\" displacements. Explicit comparison of our calculations to\nsimulations of different crystalline and disordered configurations, shows we\nsuccessfully capture the mechanics even of auxetic materials. Our method is\nvalid for residually stressed systems with non-trivial geometries, is easily\ngeneralizable to other discrete models, and opens the possibility of a rational\ndesign of elastic systems."
    },
    {
        "anchor": "Magnetism, entropy, and the first nano-machines: The efficiency of bio-molecular motors stems from reversible interactions\n$\\sim$ $k_B T$; weak bonds stabilizing intermediate states (enabling $direct$\nconversion of chemical into mechanical energy). For their (unknown) origins, we\nsuggest that a magnetically structured phase (MSP) formed via accretion of\nsuper-paramagnetic particles (S-PPs) by magnetic rocks on the Hadean Ocean\nfloor had hosted motor-like diffusion of ligand-bound S-PPs through its\ntemplate-layers; its ramifications range from optical activity to quantum\ncoherence. A gentle flux gradient offers both detailed-balance breaking\nnon-equilibrium and $asymmetry$ to a magnetic dipole, undergoing infinitesimal\nspin-alignment changes. Periodic perturbation of this background by local\nH-fields of template-partners can lead to periodic high and low-template\naffinity states, due to the dipole's magnetic degree of freedom. An\naccompanying magnetocaloric effect allows interchange between system-entropy\nand bath temperature. We speculate on a magnetic reproducer in a setting close\nto the mound-scenario of Russell and coworkers that could evolve bio- ratchets.",
        "positive": "Particle-fluid-structure interaction for debris flow impact on flexible\n  barriers: Flexible barriers are increasingly used for the protection from debris flow\nin mountainous terrain due to their low cost and environmental impact. However,\na numerical tool for rational design of such structures is still missing. In\nthis work, a hybrid computational framework is presented, using a total\nLagrangian formulation of the Finite Element Method (FEM) to represent a\nflexible barrier. The actions exerted on the structure by a debris flow are\nobtained from simultaneous simulations of the flow of a fluid-grain mixture,\nusing two conveniently coupled solvers: the Discrete Element Method (DEM)\ngoverns the motion of the grains, while the free-surface non-Newtonian fluid\nphase is solved using the Lattice-Boltzmann Method (LBM). Simulations on\nrealistic geometries show the dependence of the momentum transfer on the\nbarrier on the composition of the debris flow, challenging typical assumptions\nmade during the design process today. In particular, we demonstrate that both\ngrains and fluid contribute in a non-negligible way to the momentum transfer.\nMoreover, we show how the flexibility of the barrier reduces its vulnerability\nto structural collapse, and how the stress is distributed on its fabric,\nhighlighting potential weak points."
    },
    {
        "anchor": "Circular motion subject to external alignment under active driving:\n  nonlinear dynamics and the circle map: Hardly any real self-propelling or actively driven object is perfect. Thus,\nundisturbed motion will generally not follow straight lines but rather circular\ntrajectories. We here address self-propelled or actively driven objects that\nmove in discrete steps and additionally tempt to migrate towards a certain\ndirection by discrete angular adjustment. Overreaction in the angular alignment\nis possible. This competition implies pronounced nonlinear dynamics including\nperiod doubling and chaotic behavior in a broad parameter regime. Such behavior\ndirectly affects the appearance of the trajectories, also during collective\nmotion under spatial self-concentration.",
        "positive": "Two-Dimensional Lattice Boltzmann Model For Compressible Flows With High\n  Mach Number: In this paper we present an improved lattice Boltzmann model for compressible\nNavier-Stokes system with high Mach number. The model is composed of three\ncomponents: (i) the discrete-velocity-model by Watari and Tsutahara [Phys Rev E\n\\textbf{67},036306(2003)], (ii) a modified Lax-Wendroff finite difference\nscheme where reasonable dissipation and dispersion are naturally included,\n(iii) artificial viscosity. The improved model is convenient to compromise the\nhigh accuracy and stability. The included dispersion term can effectively\nreduce the numerical oscillation at discontinuity. The added artificial\nviscosity helps the scheme to satisfy the von Neumann stability condition.\nShock tubes and shock reflections are used to validate the new scheme. In our\nnumerical tests the Mach numbers are successfully increased up to 20 or higher.\nThe flexibility of the new model makes it suitable for tracking shock waves\nwith high accuracy and for investigating nonlinear nonequilibrium complex\nsystems."
    },
    {
        "anchor": "A neutron tomography study: probing the spontaneous crystallization of\n  randomly packed granular assemblies: We study the spontaneous crystallization of an assembly of highly\nmonodisperse steel spheres under shaking, as it evolves from localized\nicosahedral ordering towards a packing reaching crystalline ordering. Towards\nthis end, real space neutron tomography measurements on the granular assembly\nare carried out, as it is systematically subjected to a variation of frequency\nand amplitude. As expected, we see a presence of localized icosahedral ordering\nin the disordered initial state (packing fraction around 0.62). As the\nfrequency is increased for both the shaking amplitudes (0.2 and 0.6 mm) studied\nhere, there is a rise in packing fraction, accompanied by an evolution to\ncrystallinity. The extent of crystallinity is found to depend on both the\namplitude and frequency of shaking. We find that the icosahedral ordering\nremains localized and its extent does not grow significantly, while the\ncrystalline ordering grows rapidly as an ordering transition point is\napproached. In the ordered state, crystalline clusters of both face centered\ncubic (FCC) and hexagonal close packed (HCP) types are identified, the latter\nof which grows from stacking faults. Our study shows that an earlier domination\nof FCC gives way to HCP ordering at higher shaking frequencies, suggesting that\ndespite their coexistence, there is a subtle dynamical competition at play.\nThis competition depends on both shaking amplitude and frequency, as our\nresults as well as those of earlier theoretical simulations demonstrate. It is\nlikely that this involves the very small free energy difference between the two\nstructures.",
        "positive": "The paradox of contact angle selection on stretched soft solids: The interfacial mechanics of soft elastic networks play a central role in\nbiological and technological contexts. Yet, effects of solid capillarity have\nremained controversial, primarily due to the strain-dependent surface energy.\nHere we derive the equations that govern the selection of contact angles of\nliquid drops on elastic surfaces from variational principles. It is found that\nthe substrate's elasticity imposes a nontrivial condition that relates pinning,\nhysteresis and contact line mobility to the so-called Shuttleworth effect. We\nexperimentally validate our theory for droplets on a silicone gel, revealing an\nenhanced contact line mobility when stretching the substrate."
    },
    {
        "anchor": "Liquid crystalline growth within a phase-field crystal model: By using a phase-field crystal (PFC) model, the liquid-crystal growth of the\nplastic triangular phase is simulated with emphasis on crystal shape and\ntopological defect formation. The equilibrium shape of a plastic triangular\ncrystal (PTC) grown from a isotropic phase is compared with that grown from a\ncolumnar/smectic A (CSA) phase. While the shape of a PTC nucleus in the\nisotropic phase is almost identical to that of a classical PFC model, the shape\nof a PTC nucleus in CSA is affected by the orientation of stripes in the CSA\nphase, and irregular hexagonal, elliptical, octagonal, and rectangular shapes\nare obtained. Concerning the dynamics of the growth process we analyse the\ntopological structure of the nematic-order, which starts from nucleation of\n$+\\frac{1}{2}$ and $-\\frac{1}{2}$ disclination pairs at the PTC growth front\nand evolves into hexagonal cells consisting of $+1$ vortices surrounded by six\nsatellite $-\\frac{1}{2}$ disclinations. It is found that the orientational and\nthe positional order do not evolve simultaneously, the orientational order\nevolves behind the positional order, leading to a large transition zone, which\ncan span over several lattice spacings.",
        "positive": "Morphology of gold nanoparticles determined by full-curve fitting of the\n  light absorption spectrum. Comparison with X-ray scattering and electron\n  microscopy data: UV-Vis absorption spectroscopy is frequently used to characterize the size\nand shape of gold nanoparticles. We present a full-spectrum model that yields\nreliable results for the commonly encountered case of mixtures of spheres and\nrods in varying proportions. We determine the volume fractions of the two\npopulations, the aspect ratio distribution of the nanorods (average value and\nvariance) and the interface damping parameter. We validate the model by\nchecking the fit results against small-angle X-ray scattering and transmission\nelectron microscopy data and show that correctly accounting for the\npolydispersity in aspect ratio is essential for a quantitative description of\nthe longitudinal plasmon peak."
    },
    {
        "anchor": "Mechanical relaxation behavior of polyurethanes reinforced with the in\n  situ-generated sodium silica-polyphosphate nanophase: Further exploration of hybrid organic/inorganic composites (polyurethane\nbased with inorganic material sodium silica polyphosphate) properties with\nmechanical relaxometer gives ability to analyze microstructure of such\nmaterials in terms of chain reptation tubes filler's fractal aggregates and\nstress amplification.",
        "positive": "Asymmetric rectified electric and concentration fields in multicomponent\n  electrolytes with surface reactions: Recent studies have utilized AC fields and electrochemical reactions in\nmulticomponent electrolyte solutions to control colloidal assembly. However,\ntheoretical investigations have thus far been limited to binary electrolytes\nand have overlooked the impact of electrochemical reactions. In this study, we\naddress these limitations by analyzing a system with multicomponent\nelectrolytes, while also relaxing the assumption of ideally blocking electrodes\nto capture the effect of surface electrochemical reactions. Through a regular\nperturbation analysis in the low-applied-potential regime, we solve the\nPoisson-Nernst-Planck equations and obtain effective equations for electrical\npotential and ion concentrations. By employing a combination of numerical and\nanalytical calculations, our analysis reveals a significant finding:\nelectrochemical reactions alone can generate asymmetric rectified electric\nfields (AREFs), i.e., time-averaged, long-range electric fields, even when the\ndiffusivities of the ionic species are equal. This finding expands our\nunderstanding beyond the conventional notion that AREFs arise solely from\ndiffusivity contrast. Furthermore, we demonstrate that AREFs induced by\nelectrochemical reactions can be stronger than those resulting from asymmetric\ndiffusivities. Additionally, we report the emergence of asymmetric rectified\nconcentration fields (ARCFs), i.e., time-averaged long-range concentration\nfields, which supports the electrodiffusiophoresis mechanism of colloidal\nassembly observed in experiments. We also derive analytical expressions for\nAREFs and ARCFs, emphasizing the role of imbalances in ionic strength and\ncharge densities, respectively, as the driving forces behind their formation.\nThe results presented in this article advance the field of colloidal assembly\nand also have implications for improved understanding of electrolyte transport\nin electrochemical devices."
    },
    {
        "anchor": "Water Dynamics at Rough Interfaces: We use molecular dynamics computer simulations and nuclear magnetic resonance\nexperiments to investigate the dynamics of water at interfaces of molecular\nroughness and low mobility. We find that, when approaching such interfaces, the\nstructural relaxation of water, i.e., the $\\alpha$ process, slows down even\nwhen specific attractive interactions are absent. This prominent effect is\naccompanied by a smooth transition from Vogel to Arrhenius temperature\ndependence and by a growing importance of jump events. Consistently, at protein\nsurfaces, deviations from Arrhenius behavior are weak when free water does not\nexist. Furthermore, in nanoporous silica, a dynamic crossover of liquid water\noccurs when a fraction of solid water forms near 225 K and, hence, the liquid\ndynamics changes from bulk-like to interface-dominated. At sufficiently low\ntemperatures, water exhibits a quasi-universal $\\beta$ process, which is\ncharacterized by an activation energy of $E_a\\!=\\!0.5$ eV and involves\nanisotropic reorientation about large angles. As a consequence of its large\namplitude, the faster $\\beta$ process destroys essentially all orientational\ncorrelation, rendering observation of a possible slower $\\alpha$ process\ndifficult in standard experiments. Nevertheless, we find indications for the\nexistence of structural relaxation down to a glass transition of interfacial\nwater near 185 K. Hydrated proteins show a highly restricted backbone motion\nwith an amplitude, which decreases upon cooling and vanishes at comparable\ntemperatures, providing evidence for a high relevance of water rearrangements\nin the hydration shell for secondary protein relaxations.",
        "positive": "Connecting elasticity and effective interactions of neutral microgels:\n  the validity of the Hertzian model: An important open problem in materials science is whether a direct connection\nexists between single-particle elastic properties and the macroscopic bulk\nbehavior. Here we address this question by focusing on the archetype of soft\ncolloids: thermoresponsive microgels. These colloidal-sized polymer networks\nare often assumed to interact through a simple Hertzian potential, a classic\nmodel in linear elasticity theory. By developing an appropriate methodology,\nthat can be generalized to any kind of soft particle, we are able to calculate\nall the elastic moduli of non-ionic microgels across their volume phase\ntransition (VPT). Remarkably, we reproduce many features seen in experiments,\nincluding the appearance of a minimum of the Poisson's ratio close to the VPT.\nBy calculating the particle-particle effective interactions and the resulting\ncollective behavior, we find that the Hertzian model works well up to moderate\nvalues of the packing fraction."
    },
    {
        "anchor": "Mechanical impulse propagation in a packing of 3D spheres confined at\n  constant pressure: Mechanical impulse propagation in granular media depends strongly on the\nimposed confinement conditions. In this work, the propagation of sound in a\ngranular packing contained by flexible walls that enable confinement under\nhydrostatic pressure conditions is investigated. This configuration also allows\nthe form of the input impulse to be controlled by means of an instrumented\nimpact pendulum. The main characteristics of mechan- ical wave propagation are\nanalyzed, and it is found that the wave speed as function of the wave amplitude\nof the propagating pulse obeys the predictions of the Hertz contact law. Upon\nincreasing the confinement pressure, a continuous transition from nonlinear to\nlinear propagation is observed. Our results show that in the low-confinement\nregime, the attenuation increases with an increasing impulse amplitude for\nnonlinear pulses, whereas it is a weak function of the confinement pressure for\nlinear waves.",
        "positive": "Thermally activated flow in models of amorphous solids: Amorphous solids yield at a critical value $\\Sigma_c$ of the imposed stress\n$\\Sigma$ through a dynamical phase transition. While sharp in athermal systems,\nthe presence of thermal fluctuations leads to the rounding of the transition\nand thermally activated flow even below $\\Sigma_c$. Here, we study the steady\nstate thermal flow of amorphous solids using a mesoscopic elasto-plastic model.\nIn the Hebraud-Lequex (HL) model we provide an analytical solution of the\nthermally activated flow at low temperature. We then propose a general scaling\nlaw that also describes the transition rounding. Finally, we find that the\nscaling law holds in numerical simulations of the HL model, a 2D elasto-plastic\nmodel, and in previously published molecular dynamics simulations of 2D\nLennard-Jones glass."
    },
    {
        "anchor": "Fluid-solid phase-separation in hard-sphere mixtures is unrelated to\n  bond-percolation: In a recent letter, Buhot proposes that entropy driven phase-separation in\nhard-core binary mixtures is directly related to a bond-percolation transition.\nHowever, at least for binary hard-sphere mixtures, calculations based on an\naccurate approximation to g_{ll}(r) demonstrate that n_b varies widely along\nthe phase-boundaries calculated directly by simulations, implying that\nbond-percolation is unrelated to the phase-separation in these systems.",
        "positive": "Combined macro- and micro-rheometer for use with Langmuir monolayers: A Langmuir monolayer trough that is equipped for simultaneous microrheology\nand standard rheology measurements has been constructed. The central elements\nare the trough itself with a full range of optical tools accessing the\nair-water interface from below the trough and a portable knife-edge torsion\npendulum that can access the interface from above. The ability to\nsimultaneously measure the mechanical response of Langmuir monolayers on very\ndifferent lengths scales is an important step in for our understanding of the\nmechanical response of such systems."
    },
    {
        "anchor": "Food grade nanoemulsions preparation by rotor-stator homogenization: High-pressure homogenizers, typically used for producing nanoemulsions at the\nindustrial scale, are energy and maintenance intensive, and limited to produce\nonly dilute, low viscosity nanoemulsions. We propose an alternative approach to\nproduce dilute to concentrated food-grade nanoemulsions with droplet size\nranging between 100 and 500 nm using rotor-stator homogenization. Gum Arabic\n(GA) or modified starch (MS) was used as both viscosity modifier and emulsion\nstabilizer. GA and MS have relatively low surface activity compared to the\ncommon low-molecular-mass surfactants used typically for nanoemulsion\npreparation. The main differences between GA and MS are the lower viscosity of\nthe GA solutions, compared to MS solutions, and the faster adsorption of MS, as\ncompared to GA. The obtained results show that stable nanoemulsions are formed\nby rotor-stator homogenization when the rapidly adsorbing MS is used as\nemulsifier. Much larger drops are formed during emulsification with GA, which\nis due to significant drop-drop coalescence in the respective emulsions. The\nexperimental results for the nanoemulsions prepared with MS are well-described\nby the theoretical expression for emulsification in turbulent viscous regime,\nafter proper account for the effects of temperature and drop-drop interactions\nin the sheared emulsions.",
        "positive": "A Stochastic Evolutionary Model Exhibiting Power-Law Behaviour with an\n  Exponential Cutoff: Recently several authors have proposed stochastic evolutionary models for the\ngrowth of complex networks that give rise to power-law distributions. These\nmodels are based on the notion of preferential attachment leading to the ``rich\nget richer'' phenomenon. Despite the generality of the proposed stochastic\nmodels, there are still some unexplained phenomena, which may arise due to the\nlimited size of networks such as protein and e-mail networks. Such networks may\nin fact exhibit an exponential cutoff in the power-law scaling, although this\ncutoff may only be observable in the tail of the distribution for extremely\nlarge networks. We propose a modification of the basic stochastic evolutionary\nmodel, so that after a node is chosen preferentially, say according to the\nnumber of its inlinks, there is a small probability that this node will be\ndiscarded. We show that as a result of this modification, by viewing the\nstochastic process in terms of an urn transfer model, we obtain a power-law\ndistribution with an exponential cutoff. Unlike many other models, the current\nmodel can capture instances where the exponent of the distribution is less than\nor equal to two. As a proof of concept, we demonstrate the consistency of our\nmodel by analysing a yeast protein interaction network, the distribution of\nwhich is known to follow a power law with an exponential cutoff."
    },
    {
        "anchor": "Modelling realistic microgels in an explicit solvent: Thermoresponsive microgels are polymeric colloidal networks that can change\ntheir size in response to a temperature variation. This peculiar feature is\ndriven by the nature of the solvent-polymer interactions, which triggers the\nso-called volume phase transition from a swollen to a collapsed state above a\ncharacteristic temperature. Recently, an advanced modelling protocol to\nassemble realistic, disordered microgels has been shown to reproduce\nexperimental swelling behavior and form factors. In the original framework, the\nsolvent was taken into account in an implicit way, condensing solvent-polymer\ninteractions in an effective attraction between monomers. To go one step\nfurther, in this work we perform simulations of realistic microgels in an\nexplicit solvent. We identify a suitable model which fully captures the main\nfeatures of the implicit model and further provides information on the solvent\nuptake by the interior of the microgel network and on its role in the collapse\nkinetics. These results pave the way for addressing problems where solvent\neffects are dominant, such as the case of microgels at liquid-liquid\ninterfaces.",
        "positive": "Steady Granular Flow in a Rotating Drum: Universal description of\n  stress, velocity and packing fraction profiles covering grain shape effects\n  from convex to very concave: The flow behavior of granular matter is significantly influenced by the shape\nof constituent particles. This effect is particularly pronounced for very\nconcave particles, which exhibit unique flow characteristics such as higher\nporosity and sharper phase transitions between jamming and unjamming states.\nDespite the richness and ubiquitousness of these systems, our understanding of\ntheir intricate flow behavior and the local mechanisms driving these behaviors\nremains incomplete. In this work, we investigate the effect of particle shape,\nranging from spherical to highly concave, on steady flows in a rotating drum -\na system that facilitates a continuous phase transition from a jamming state at\ngreater depths to an unjamming state at shallower regions. We develop an\nanalytical model to elucidate granular behavior within the rotating drum: (i)\nFirstly, by decomposing the shear stress, we reconcile the discrepancy between\nsimulation data and theoretical predictions, establishing a relationship with\nthe angle of repose. (ii)Secondly, we extend the generalized Bagnold scaling ,\ncoupled with a non-local fluidity relation based on packing fraction, providing\na framework for a correlation between shear stress, shear rate, and packing\nfraction. Additionally, we introduce a characteristic length to quantify the\ninfluence of particle shape and drum speed. This analytical model offers\nexplicit functional forms for physical quantity profiles, which are validated\nexperimentally in a thin rotating drum and numerically in a two-dimensional\nrotating drum. Our results demonstrate that this model accurately describes the\nchange of velocity due to the phase transition of granular flow within a\nrotating drum. Moreover, for different shapes of particle and drum speeds, the\ncharacteristic length captures the interplay between shear stress, shear rate,\nand the variation of packing fraction."
    },
    {
        "anchor": "The Glass Transition and Liquid-Gas Spinodal Boundaries of Metastable\n  Liquids: A liquid can exist under conditions of thermodynamic stability or\nmetastability within boundaries defined by the liquid-gas spinodal and the\nglass transition line. The relationship between these boundaries has been\ninvestigated previously using computer simulations, the energy landscape\nformalism, and simplified model calculations. We calculate these stability\nboundaries semi-analytically for a model glass forming liquid, employing\naccurate liquid state theory and a first-principles approach to the glass\ntransition. These boundaries intersect at a finite temperature, consistent with\nprevious simulation-based studies.",
        "positive": "Persistent current of atoms in a ring optical lattice: We consider a small ensemble of Bose atoms in a ring optical lattice with\nweak disorder. The atoms are assumed to be initially prepared in a superfluid\nstate with non-zero quasimomentum and, hence, may carry matter current. It is\nfound that the atomic current persists in time for a low value of the\nquasimomentum but decays exponentially for a high (around one quater of the\nBrillouin zone) quasimomentum. The explanation is given in terms of low- and\nhigh-energy spectra of the Bose-Hubbard model, which we describe using the\nBogoliubov and random matrix theories, respectively."
    },
    {
        "anchor": "Statistical Physics of the Jamming Transition: The Search for Simple\n  Models: We investigate universal features of the jamming transition in granular\nmaterials, colloids and glasses. We show that the jamming transition in these\nsystems has common features: slowing of response to external perturbation, and\nthe onset of structural heterogeneities.",
        "positive": "Rheology of a sonofluidized granular packing: We report experimental measurements on the rheology of a dry granular\nmaterial under a weak level of vibration generated by sound injection. First,\nwe measure the drag force exerted on a wire moving in the bulk. We show that\nwhen the driving vibration energy is increased, the effective rheology changes\ndrastically: going from a non-linear dynamical friction behavior - weakly\nincreasing with the velocity- up to a linear force-velocity regime. We present\na simple heuristic model to account for the vanishing of the stress dynamical\nthreshold at a finite vibration intensity and the onset of a linear\nforce-velocity behavior. Second, we measure the drag force on spherical\nintruders when the dragging velocity, the vibration energy, and the diameters\nare varied. We evidence a so-called ''geometrical hardening'' effect for\nsmaller size intruders and a logarithmic hardening effect for the velocity\ndependence. We show that this last effect is only weakly dependent on the\nvibration intensity."
    },
    {
        "anchor": "Folding kinetics of a polymer [corrigendum]: In our original article (Phys. Chem. Chem. Phys., 2012, 14, 60446053) a\nconvergence problem resulted in an averaging error in computing the entropy\nfrom a set of Wang-Landau Monte-Carlo simulations. Here we report corrected\nresults for the freezing temperature of the homopolymer chain as a function of\nthe range of the non-bonded interaction. We find that the previously reported\nforward-flux sampling (FFS) and brute-force (BF) simulation results are in\nagreement with the revised Wang-Landau (WL) calculations. This confirms the\nutility of FFS for computing crystallisation rates in systems of this kind.",
        "positive": "Reentrant Disordering of Colloidal Molecular Crystals on 2D Periodic\n  Substrates: We study colloidal ordering and disordering on two-dimensional periodic\nsubstrates where the number of colloids per substrate minima is two or three.\nThe colloids form dimer or trimer states with orientational ordering, referred\nto as colloidal molecular crystals. At a fixed temperature such that, in the\nabsence of a substrate, the colloids are in a triangular floating solid state,\nupon increasing the substrate strength we find a transition to an ordered\ncolloidal molecular crystal state, followed by a transition to a disordered\nstate where the colloids still form dimers or trimers but the orientational\norder is lost. These results are in agreement with recent experiments."
    },
    {
        "anchor": "The Mystery of the Ramsey Fringe that Didn't Chirp: We use precision microwave spectroscopy of magnetically trapped, ultra-cold\n87Rb to characterize intra- and inter-state density correlations. The cold\ncollision shifts for both normal and condensed clouds are measured. The results\nverify the presence of the sometimes controversial \"factors of two\", in\nnormal-cloud mean-field energies, both within a particular state and between\ntwo distinct spin species. One might expect that as two spin species decohere,\nthe inter-state factor of two would revert to unity, but the associated\nfrequency chirp one naively expects from such a trend is not observed in our\ndata.",
        "positive": "Self-diffusion in binary blends of cyclic and linear polymers: A lattice model is used to estimate the self-diffusivity of entangled cyclic\nand linear polymers in blends of varying compositions. To interpret simulation\nresults, we suggest a minimal model based on the physical idea that constraints\nimposed on a cyclic polymer by infiltrating linear chains have to be released,\nbefore it can diffuse beyond a radius of gyration. Both, the simulation, and\nrecently reported experimental data on entangled DNA solutions support the\nsimple model over a wide range of blend compositions, concentrations, and\nmolecular weights."
    },
    {
        "anchor": "Phase behavior of a deionized binary mixture of charged spheres in the\n  presence of gravity: We report on the phase behavior of an aqueous binary charged sphere\nsuspension under exhaustively deionized conditions as a function of number\nfraction of small particles p and total number density n. The mixture of size\nratio 0.557 displays a complex phase diagram. Formation of bcc crystals with no\ncompositional order dominates. We observe a region of drastically decreased\ncrystal stability at 0.55 < p < 0.95 with the minimum located at p = 0.8 +/-\n0.05 at densities above n = 26um-3. A peaked region of enhanced stability is\nobserved at p = 0.4. Further light scattering experiments were conducted to\ncharacterize the crystallization time scales, the density profiles and the\ncomposition of formed phases. For 0.82 > p > 0.95 crystal formation is\npartially assisted by gravity, i.e. gravitational separation of the two species\nprecedes crystal formation samples in the coexistence range. In the composition\nrange corresponding to the decreased crystal stability only lower bounds of the\nfreezing and melting line are obtained, but the general shape of the phase\ndiagram is retained. At p = 0.93 and n = 43um-3 two different crystalline\nphases coexist in the bulk, while at p = 0.4 additional Bragg peaks appear in\nthe static light scattering experiments. This strongly suggests that we observe\na eutectic in the region of decreased stability, while the enhanced stability\nat p = 0.4 seems to correlate with compound formation.",
        "positive": "Simulations of a lattice model of two-headed linear amphiphiles:\n  influence of amphiphile asymmetry: Using a 2D lattice model, we conduct Monte Carlo simulations of micellar\naggregation of linear-chain amphiphiles having two solvophilic head groups. In\nthe context of this simple model, we quantify how the amphiphile architecture\ninfluences the critical micelle concentration (CMC), with a particular focus on\nthe role of the asymmetry of the amphiphile structure. Accordingly, we study\nall possible arrangements of the head groups along amphiphile chains of fixed\nlength $N=12$ and 16 molecular units. This set of idealized amphiphile\narchitectures approximates many cases of symmetric and asymmetric gemini\nsurfactants, double-headed surfactants and boloform surfactants. Consistent\nwith earlier results, we find that the number of spacer units $s$ separating\nthe heads has a significant influence on the CMC, with the CMC increasing with\n$s$ for $s<N/2$. In comparison, the influence of the asymmetry of the chain\narchitecture on the CMC is much weaker, as is also found experimentally."
    },
    {
        "anchor": "Relativistic Theory of Superconductivity: The relativistic generalization of the theory of superconductivity is\nreviewed with respect to its conceptual basis and first applications. The\nconstruction of relativistically covariant order parameters for superconductors\nis outlined and the generalization of the Dirac equation for the\nsuperconducting state is presented. A weakly relativistic expansion of this\nequation leads to the Pauli equation for superconductors, which describes the\nlowest-order relativistic corrections to the conventional theory of\nsuperconductivity. The physics of these corrections is discussed, and the\nprospects for experimental detection of relativistic effects in superconductors\nare examined.",
        "positive": "Two remarks on wetting and emulsions: This paper is extracted from an opening address given at the workshop\n\"Wetting: from microscopic origins to industrial applications\" (Giens, May\n  6-12, 2000). It discusses two special points a) the nature of line energies\nfor a contact line b) the aging of emulsions."
    },
    {
        "anchor": "Mesoscopic Simulation of Electrohydrodynamic Patterns in Positive and\n  Negative Nematic Liquid Crystals: For the first time the electrohydrodynamic convection (EHC) of nematic liquid\ncrystals is studied via fully nonlinear simulation. As a system of rich\npattern-formation the EHC is mostly studied with negative nematic liquid\ncrystals experimentally, and sometimes with the help of theoretical instability\nanalysis in the linear regime. Up to now there is only weakly nonlinear\nsimulation for a step beyond the emergence of steady convection rolls. In this\nwork we modify the liquid crystal stochastic rotational model (LC SRD) [Lee et\nal., J. Chem. Phys., 2015, 142, 164110] to incorporate the field alignment\nmechanism for positive and negative nematic liquid crystals. The convection\npatterns and their flow dynamics in the presence of external electric field are\nstudied. Our results predict the similar optical convection patterns in the\nreflected polarized light when one uses positive and negative types of nematic\nliquid crystals. However in the emerged flow fields, surprisingly, the driving\nareas of convection rolls are different for different types of LCs. Their\napplication for nematic colloidal transportation in microfluidics is discussed.",
        "positive": "Integration algorithms of elastoplasticity for ceramic powder compaction: Inelastic deformation of ceramic powders (and of a broad class of rock-like\nand granular materials), can be described with the yield function proposed by\nBigoni and Piccolroaz (2004, Yield criteria for quasibrittle and frictional\nmaterials. Int. J. Solids and Structures, 41, 2855-2878). This yield function\nis not defined outside the yield locus, so that 'gradient-based' integration\nalgorithms of elastoplasticity cannot be directly employed. Therefore, we\npropose two ad hoc algorithms: (i.) an explicit integration scheme based on a\nforward Euler technique with a 'centre-of-mass' return correction and (ii.) an\nimplicit integration scheme based on a 'cutoff-substepping' return algorithm.\nIso-error maps and comparisons of the results provided by the two algorithms\nwith two exact solutions (the compaction of a ceramic powder against a rigid\nspherical cup and the expansion of a thick spherical shell made up of a green\nbody), show that both the proposed algorithms perform correctly and accurately."
    },
    {
        "anchor": "Self Similar Properties of Avalanche Statistics in a Simple Turbulent\n  Model: In this paper, we consider a simplified model of turbulence for large\nReynolds numbers driven by a constant power energy input on large scales. In\nthe statistical stationary regime, the behaviour of the kinetic energy is\ncharacterised by two well defined phases: a laminar phase where the kinetic\nenergy grows linearly for a (random) time $t_w$ followed by abrupt\navalanche-like energy drops of sizes $S$ due to strong intermittent\nfluctuations of energy dissipation. We study the probability distribution\n$P[t_w]$ and $P[S]$ which both exhibit a quite well defined scaling behaviour.\nAlthough $t_w$ and $S$ are not statistically correlated, we suggest and\nnumerically checked that their scaling properties are related based on a\nsimple, but non trivial, scaling argument. We propose that the same approach\ncan be used for other systems showing avalanche-like behaviour such as\namorphous solids and seismic events.",
        "positive": "Modified multiplicative decomposition model for tissue growth: Beyond\n  the initial stress-free state: The multiplicative decomposition model is widely employed for predicting\nresidual stresses and morphologies of biological tissues due to growth.\nHowever, it relies on the assumption that the tissue is initially in a\nstress-free state, which conflicts with the observations that any growth state\nof tissue is under a significant level of residual stresses that helps to\nmaintain its ideal mechanical conditions. Here, we propose a modified\nmultiplicative decomposition model where the initial state (or reference\nconfiguration) of biological tissue is endowed with residual stress instead of\nbeing stress-free. Releasing theoretically the initial residual stress, the\ninitially stressed state is first transmitted into a virtual stress-free state,\nresulting in an initial elastic deformation. The initial virtual stress-free\nstate subsequently grows to another counterpart with a growth deformation and\nthe latter is further integrated into its natural configuration with an\nexcessive elastic deformation that ensures tissue compatibility. With this\ndecomposition, the total deformation may be expressed as the product of elastic\ndeformation, growth deformation and initial elastic deformation, while the\ncorresponding free energy density depends on the initial residual stress and\nthe total deformation. We address three key issues: explicit expression of the\nfree energy density,predetermination of the initial elastic deformation, and\ninitial residual stress. Finally, we consider a tubular organ to demonstrate\nthe effects of the proposed initial residual stress on stress distribution and\non shape formation through an incremental stability analysis. Our results\nsuggest that the initial residual stress exerts a major influence on the growth\nstress and the morphology of tissues."
    },
    {
        "anchor": "Cooperative Behavior and Pattern Formation in Mixtures of Driven and\n  Nondriven Colloidal Assemblies: We simulate a disordered assembly of particles interacting through a\nrepulsive Yukawa potential with a small fraction of the particles coupled to an\nexternal drive. Distortions in the arrangement of the nondriven particles\nproduce a dynamically induced effective attraction between the driven\nparticles, giving rise to intermittent one-dimensional stringlike structures.\nThe velocity of a moving string increases with the number of driven particles\nin the string. We identify the average stable string length as a function of\ndriving force, background particle density, and particle charge. This model\nrepresents a new type of collective transport system composed of interacting\nparticles moving through deformable disorder.",
        "positive": "Can the roles of polar and non-polar moieties be reversed in non-polar\n  solvents?: Using thermodynamics integration, we study the solvation free energy of 18\namino acid side chain equivalents in solvents with different polarity, ranging\nfrom the most polar water to the most non-polar cyclohexane. The amino acid\nside chain equivalents are obtained from the 20 natural amino acids by\nreplacing the backbone part with a hydrogen atom, and discarding proline and\nglycine that have special properties. A detailed analysis of the relative\nsolvation free energies suggests how it is possible to achieve a robust and\nunambiguous hydrophobic scale for the amino acids. By discriminating the\nrelative contributions of the entropic and enthalpic terms, we find strong\nnegative correlations in water and ethanol, associated with the well-known\nentropy-enthalpy compensation, and a much reduced correlation in cyclohexane.\nThis shows that in general the role of the polar and non-polar moieties cannot\nbe reversed in a non-polar solvent. Our findings are compared with past\nexperimental as well as numerical results, and may shed additional light on the\nunique role of water as biological solvent."
    },
    {
        "anchor": "Temperature dependence of spatially heterogeneous dynamics in a model of\n  viscous silica: Molecular dynamics simulations are performed to study spatially heterogeneous\ndynamics in a model of viscous silica above and below the critical temperature\nof the mode coupling theory, $T_{MCT}$. Specifically, we follow the evolution\nof the dynamic heterogeneity as the temperature dependence of the transport\ncoefficients shows a crossover from non-Arrhenius to Arrhenius behavior when\nthe melt is cooled. It is demonstrated that, on intermediate time scales, a\nsmall fraction of oxygen and silicon atoms are more mobile than expected from a\nGaussian approximation. These highly mobile particles form transient clusters\nlarger than that resulting from random statistics, indicating that dynamics are\nspatially heterogeneous. An analysis of the clusters reveals that the mean\ncluster size is maximum at times intermediate between ballistic and diffusive\nmotion, and the maximum size increases with decreasing temperature. In\nparticular, the growth of the clusters continues when the transport\ncoefficients follow an Arrhenius law. These findings imply that the structural\nrelaxation in silica cannot be understood as a statistical bond breaking\nprocess. Though the mean cluster sizes for silica are at the lower end of the\nspectrum of values reported in the literature, we find that spatially\nheterogeneous dynamics in strong and fragile glass formers are similar on a\nqualitative level. However, different from results for fragile liquids, we show\nthat correlated particle motion along quasi one-dimensional, string-like paths\nis of little importance for the structural relaxation in this model of silica,\nsuggesting that string-like motion is suppressed by the presence of covalent\nbonds.",
        "positive": "Direct Measurement of the Elastohydrodynamic Lift Force at the Nanoscale: We present the first direct measurement of the elastohydrodynamic lift force\nacting on a sphere moving within a viscous liquid, near and along a soft\nsubstrate under nanometric confinement. Using atomic force microscopy, the lift\nforce is probed as a function of the gap size, for various driving velocities,\nviscosities, and stiffnesses. The force increases as the gap is reduced and\nshows a saturation at small gap. The results are in excellent agreement with\nscaling arguments and a quantitative model developed from the soft lubrication\ntheory, in linear elasticity, and for small compliances. For larger\ncompliances, or equivalently for smaller confinement length scales, an\nempirical scaling law for the observed saturation of the lift force is given\nand discussed."
    },
    {
        "anchor": "Topology, geometry and mechanics of strongly stretched and twisted\n  filaments: Soft elastic filaments that can be stretched, bent and twisted exhibit a\nrange of topologically and geometrically complex morphologies that include\nplectonemes, solenoids, knot-like and braid-like structures. We combine\nnumerical simulations of soft elastic filaments that account for geometric\nnonlinearities and self-contact to map out these structures in a phase diagram\nthat is a function of extension and twist density, consistent with previous\nexperimental observations. By using ideas from computational topology, we also\ntrack the interconversion of link, twist and writhe in these geometrically\ncomplex physical structures. This allows us to explain recent experiments on\nfiber-based artificial muscles that use the conversion of writhe to extension\nor contraction, exposing the connection between topology, geometry and\nmechanics in an everyday practical setting.",
        "positive": "Characterizing protein crystal contacts and their role in\n  crystallization: rubredoxin as a case study: The fields of structural biology and soft matter have independently sought\nout fundamental principles to rationalize protein crystallization. Yet the\nconceptual differences and the limited overlap between the two disciplines have\nthus far prevented a comprehensive understanding of the phenomenon to emerge.\nWe conduct a computational study of proteins from the rubredoxin family that\nbridges the two fields. Using atomistic simulations, we characterize their\ncrystal contacts, and accordingly parameterize patchy particle models.\nComparing the phase diagrams of these schematic models with experimental\nresults enables us to critically examine the assumptions behind the two\napproaches. The study also reveals features of protein-protein interactions\nthat can be leveraged to crystallize proteins more generally."
    },
    {
        "anchor": "Experimental setup for measuring the barocaloric effect in polymers:\n  Application to natural rubber: Barocaloric materials have shown to be promising alternatives to the\nconventional vapor-compression refrigeration technologies. Nevertheless,\nbarocaloric effect ({\\sigma}b-CE) has not been extensively examined for many\nclasses of materials up to now. Aiming at fulfilling this gap, this paper\ndescribes the development of a high-pressure experimental setup for measuring\nthe {\\sigma}b-CE in polymers. The design allows simultaneous measurements of\ntemperature, pressure and strain during the barocaloric cycle. The system\nproved to be fully-functional through basic experiments using natural rubber.\nSamples exhibited large temperature variations associated to the {\\sigma}b-CE.\nStrain-temperature curves were also obtained, which could allow indirect\nmeasurements of the isothermal entropy change.",
        "positive": "Giant ripples on comet 67P/Churyumov-Gerasimenko sculpted by sunset\n  thermal wind: Explaining the unexpected presence of dune-like patterns at the surface of\nthe comet 67P/Churyumov-Gerasimenko requires conceptual and quantitative\nadvances in the understanding of surface and outgassing processes. We show here\nthat vapor flow emitted by the comet around its perihelion spreads laterally in\na surface layer, due to the strong pressure difference between zones\nilluminated by sunlight and those in shadow. For such thermal winds to be dense\nenough to transport grains -- ten times greater than previous estimates --\noutgassing must take place through a surface porous granular layer, and that\nlayer must be composed of grains whose roughness lowers cohesion consistently\nwith contact mechanics. The linear stability analysis of the problem, entirely\ntested against laboratory experiments, quantitatively predicts the emergence of\nbedforms in the observed wavelength range, and their propagation at the scale\nof a comet revolution. Although generated by a rarefied atmosphere, they are\nparadoxically analogous to ripples emerging on granular beds submitted to\nviscous shear flows. This quantitative agreement shows that our understanding\nof the coupling between hydrodynamics and sediment transport is able to account\nfor bedform emergence in extreme conditions and provides a reliable tool to\npredict the erosion and accretion processes controlling the evolution of small\nsolar system bodies."
    },
    {
        "anchor": "Viscometric Functions and Rheo-optical Properties of Dilute Polymer\n  Solutions: Comparison of FENE-Fraenkel Dumbbells with Rodlike Models: Rigid macromolecules or polymer chains with persistence length on the order\nof the contour length (or greater) have traditionally been modelled as rods or\nvery stiff springs. The FENE-Fraenkel-spring dumbbell, which is finitely\nextensible about a non-zero natural length with tunable harmonic stiffness, is\none such model which has previously been shown to reproduce bead-rod behaviour\nin the absence of hydrodynamic interactions. The force law for the\nFENE-Fraenkel spring reduces to the Hookean or FENE spring force law for\nappropriately chosen values of the spring parameters. It is consequently\npossible to explore the crossover region between the limits of bead-spring and\nbead-rod behaviour by varying the parameters suitably. In this study, using a\nsemi-implicit predictor-corrector Brownian dynamics algorithm, the\nFENE-Fraenkel spring is shown to imitate a rod with hydrodynamic interactions\nwhen spring stiffness, extensibility and simulation timestep are chosen\ncarefully. By relaxing the spring stiffness and extensibility, the\nFENE-Fraenkel spring can also reproduce spring-like behaviour, such as a\ncrossover from $-1/3$ to $-2/3$ power-law scaling in the viscosity with shear\nrate, and a change from positive to negative second normal stress difference.\nFurthermore, comparisons with experimental data on the viscosity and linear\ndichroism of high aspect ratio, rigid macromolecules shows that the\nextensibility and stiffness of the FENE-Fraenkel spring allows for equal or\nimproved accuracy in modelling inflexible molecules compared to rodlike models.",
        "positive": "Anisotropic frictional model for an object sliding in a granular media: Several locomotion strategies are based on the anisotropic nature of the\nforces experienced by the moving body with its environment. We report\nexperiments on the anisotropy of the frictional force experienced by a cylinder\nmoving in a granular medium as a function of the orientation $\\alpha$ between\nthe cylinder and its velocity. The component of the force in the direction\nparallel to the velocity of the cylinder is always higher than the\nperpendicular component and the force is therefore anisotropic. While the\nparallel component increases continuously with the cylinder angle $\\alpha$, we\nobserve that the perpendicular component reaches a maximum value for an\norientation of $\\alpha_c \\simeq 35^\\circ$. In order to rationalise these\nobservations, we have developed a theoretical model which assumes that the\nmechanical energy required to move the cylinder is dissipated by friction and\nestablishes a relationship between the parallel and perpendicular force\ncomponents that is consistent with experiments."
    },
    {
        "anchor": "Reinforcement Learning of Artificial Microswimmers: The behavior of living systems is based on the experience they gained through\ntheir interactions with the environment [1]. This experience is stored in the\ncomplex biochemical networks of cells and organisms to provide a relationship\nbetween a sensed situation and what to do in this situation [2-4]. An\nimplementation of such processes in artificial systems has been achieved\nthrough different machine learning algorithms [5, 6]. However, for microscopic\nsystems such as artificial microswimmers which mimic propulsion as one of the\nbasic functionalities of living systems [7, 8] such adaptive behavior and\nlearning processes have not been implemented so far. Here we introduce machine\nlearning algorithms to the motion of artificial microswimmers with a hybrid\napproach. We employ self-thermophoretic artificial microswimmers in a real\nworld environment [9, 10] which are controlled by a real-time microscopy system\nto introduce reinforcement learning [11-13]. We demonstrate the solution of a\nstandard problem of reinforcement learning - the navigation in a grid world.\nDue to the size of the microswimmer, noise introduced by Brownian motion if\nfound to contribute considerably to both the learning process and the actions\nwithin a learned behavior. We extend the learning process to multiple swimmers\nand sharing of information. Our work represents a first step towards the\nintegration of learning strategies into microsystems and provides a platform\nfor the study of the emergence of adaptive and collective behavior.",
        "positive": "Positronium-positronium interaction: Resonance, scattering length, and\n  Bose-Einstein condensation: The low-energy scattering of ortho positronium (Ps) by ortho Ps has been\nstudied in a full quantum mechanical coupled-channel approach. In the singlet\nchannel (total spin $s_T=0$) we find S- and P-wave resonances at 3.35 eV (width\n0.02 eV) and 5.05 eV (width 0.04 eV), respectively and a binding of 0.44 eV of\nPs$_2$. The scattering length for $s_T=0$ is 3.95 \\AA and for $s_T=2$ is 0.83\n\\AA . The small $s_T=2$ scattering length makes the spin-polarized ortho Ps\natoms an almost noninteracting ideal gas which may undergo Bose-Einstein\ncondensation."
    },
    {
        "anchor": "Current fluctuations in nanopores reveal the polymer-wall adsorption\n  potential: Modification of surface properties by polymer adsorption is a widely used\ntechnique to tune interactions in molecular experiments such as nanopore\nsensing. Here, we investigate how the ionic current noise through solid-state\nnanopores reflects the adsorption of short, neutral polymers to the pore\nsurface. The power spectral density of the noise shows a characteristic change\nupon adsorption of polymer, the magnitude of which is strongly dependent on\nboth polymer length and salt concentration. In particular, for short polymers\nat low salt concentrations no change is observed, despite verification of\ncomparable adsorption in these systems using quartz crystal microbalance\nmeasurements. We propose that the characteristic noise is generated by the\nmovement of polymers on and off the surface and perform simulations to assess\nthe feasibility of this model. Excellent agreement with experimental data is\nobtained using physically motivated simulation parameters, providing deep\ninsight into the shape of the adsorption potential and underlying processes.\nThis paves the way towards using noise spectral analysis for in situ\ncharacterisation of functionalised nanopores.",
        "positive": "A hybrid LBM-DEM framework with an improved immersed moving boundary\n  method for modelling complex particle-liquid flows involving adhesive\n  particles: This paper presents an improved immersed moving boundary model (IBM) for\nsolving complex fluid-particle interactions in a coupled lattice Boltzmann\nmethod (LBM) and an adhesive discrete element method (DEM), using the\n\"partially saturated cell\" scheme. It is shown that the existing scheme does\nnot well address the contribution of each solid particle to the fluid when\nmultiple particles intersect with the same lattice cell. This issue is\ncompletely addressed by modifying the weighting function in the partially\ncovered cells in the present study. Furthermore, a fast linear approximation\nmethod with high efficiency and good accuracy is applied to calculate the\npartially intersected volume between a particle and a lattice cell. Verified\nwith several benchmark cases, the developed hybrid IBM-LBM-DEM numerical\nframework is capable of describing the flow field between dense particles with\na relatively low grid resolution in more details, as well as effectively\ncapturing the adhesive mechanics between microspheres."
    },
    {
        "anchor": "Phoretic Interactions Between Active Droplets: Concentration gradients play a critical role in embryogenesis, bacterial\nlocomotion, as well as the motility of active particles. Particles develop\nconcentration profiles around them by dissolution, adsorption, or the\nreactivity of surface species. These gradients change the surface energy of the\nparticles, driving both their self-propulsion and governing their interactions.\nHere we uncover a regime in which solute-gradients mediate interactions between\nslowly dissolving droplets without causing autophoresis. This decoupling allows\nus to directly measure the steady-state, repulsive force, which scales with\ninterparticle distance as $F\\sim {1/r^{2}}$. Our results show that the process\nis diffusion rather than reaction rate limited, and the theoretical model\ncaptures the dependence of the interactions on droplet size and solute\nconcentration, using a single fit parameter, $l=16\\pm 3$~nm, which corresponds\nto the lengthscale of a swollen micelle. Our results shed light on the\nout-of-equilibrium behavior of particles with surface reactivity.",
        "positive": "Test of a simple and flexible S8 model molecule in alpha-s8 crystals: Alpha S8 is the most stable crystalline form, at ambient pressure and\ntemperature (STP), of elemental sulfur. In this paper we analyze the zero\npressure low temperature part of the phase diagram of this crystal, in order to\ntest a simple and flexible model molecule. The calculations consist in a series\nof molecular dynamics (MD) simulations, performed in the constant pressure-\nconstant temperature ensemble. Our calculations show that this model, that\ngives good results for three crystalline phases at STP and T>~300 K, fails at\nlow temperatures, predicting a structural phase transition at 200 K where there\nshould be none."
    },
    {
        "anchor": "Free energy of a folded polymer under cylindrical confinement: Monte Carlo computer simulations are used to study the conformational free\nenergy of a folded polymer confined to a long cylindrical tube. The polymer is\nmodeled as a hard-sphere chain. Its conformational free energy $F$ is measured\nas a function of $\\lambda$, the end-to-end distance of the polymer. In the case\nof a flexible linear polymer, $F(\\lambda)$ is a linear function in the folded\nregime with a gradient that scales as $f\\equiv |dF/d\\lambda| \\sim N^0\nD^{-1.20\\pm 0.01}$ for a tube of diameter $D$ and a polymer of length $N$. This\nis close to the prediction $f \\sim N^0 D^{-1}$ obtained from simple scaling\narguments. The discrepancy is due in part to finite-size effects associated\nwith the de-Gennes blob model. A similar discrepancy was observed for the\nfolding of a single arm of a three-arm star polymer. We also examine\nbackfolding of a semiflexible polymer of persistence length $P$ in the classic\nOdijk regime. In the overlap regime, the derivative scales $f \\sim N^0\nD^{-1.72\\pm 0.02} P^{-0.35\\pm 0.01}$, which is close to the prediction $f \\sim\nN^0 D^{-5/3} P^{-1/3}$ obtained from a scaling argument that treats\ninteractions between deflection segments at the second virial level. In\naddition, the measured free energy cost of forming a hairpin turn is\nquantitatively consistent with a recent theoretical calculation. Finally, we\nexamine the scaling of $F(\\lambda)$ for a confined semiflexible chain in the\npresence of an S-loop composed of two hairpins. While the predicted scaling of\nthe free energy gradient is the same as that for a single hairpin, we observe a\nscaling of $f \\sim D^{-1.91\\pm 0.03} P^{-0.36\\pm 0.01}$. Thus, the quantitative\ndiscrepancy between this measurement and the predicted scaling is somewhat\ngreater for S-loops than for single hairpins.",
        "positive": "Spontaneous flows and dynamics of full-integer topological defects in\n  polar active matter: Polar active matter of self-propelled particles sustain spontaneous flows\nthrough the full-integer topological defects. We study theoretically the effect\nof both polar and dipolar active forces on the flow profile around $\\pm 1$\ndefects and their interaction in the presence of both viscosity and frictional\ndissipation. The vorticity induced by the active stress is non-zero at the $+1$\ndefect contributing to the active torque acting on the defect. A near-core flow\nreversal is predicted in absence of hydrodynamic screening (zero friction) as\nobserved in numerical simulations. While $\\pm 1$ defects are sources of\nspontaneous flows due to active stresses, they become sinks of flows induced by\nthe polar active forces. We show analytically that the flow velocity induced by\npolar active forces increases away from a $\\pm 1$ defect towards the uniform\nfar-field, while its associated vorticity field decays as $1/r$ in the\nfar-field. In the friction-dominated regime, we demonstrate that the flow\ninduced by polar active forces enhances defect pair annihilation, and depends\nonly on the orientation between a pair of oppositely charged defects relative\nto the orientation of the background polarization field. Interestingly, we find\nthat this annihilation dynamics through mutual defect-defect interactions is\ndistance independent, in contradiction with the effect of dipolar active forces\nwhich decay inversely proportional to the defect separation distance. As such,\nour analyses reveals a new, truly long-ranged mechanism for the pairwise\ninteraction of oppositely-charged topological defects in polar active matter."
    },
    {
        "anchor": "Optimized Baxter Model of Protein Solutions: Electrostatics versus\n  Adhesion: A theory is set up of spherical proteins interacting by screened\nelectrostatics and constant adhesion, in which the effective adhesion parameter\nis optimized by a variational principle for the free energy. An analytical\napproach to the second virial coefficient is first outlined by balancing the\nrepulsive electrostatics against part of the bare adhesion. A theory similar in\nspirit is developed at nonzero concentrations by assuming an appropriate Baxter\nmodel as the reference state. The first-order term in a functional expansion of\nthe free energy is set equal to zero which determines the effective adhesion as\na function of salt and protein concentrations. The resulting theory is shown to\nhave fairly good predictive power for the ionic-strength dependence of both the\nsecond virial coefficient and the osmotic pressure or compressibility of\nlysozyme up to about 0.2 volume fraction.",
        "positive": "Anomalous bending of a polyelectrolyte: We report on a study of the shape of a stiff, charged rod that is subjected\nto equal and opposite force couples at its two ends. Unlike a neutral elastic\nrod, which forms a constant curvature configuration under such influences, the\ncharged rod tends to flatten in the interior and accumulate the curvature in\nthe end points, to maximally reduce the electrostatic self-repulsion. The\neffect of this nonuniform bending on the effective elasticity and on the\nstatistical conformations of a fluctuating charged rod is discussed. An\nalternative definition for the electrostatic persistence length is suggested.\nThis new definition is found to be consistent with a corresponding length that\ncan be deduced from the end-to-end distribution function of a fluctuating\npolyelectrolyte."
    },
    {
        "anchor": "Coupled Modulated Bilayers: We propose a model addressing the coupling mechanism between two spatially\nmodulated monolayers. We obtain the mean-field phase diagrams of coupled\nbilayers when the two monolayers have the same preferred modulation wavelength.\nVarious combinations of the monolayer modulated phases are obtained and their\nrelative stability is calculated. Due to the coupling, a spatial modulation in\none of the monolayers induces a similar periodic structure in the second one.\nWe have also performed numerical simulations for the case when the two\nmonolayers have different modulation wavelengths. Complex patterns may arise\nfrom the frustration between the two incommensurate but annealed structures.",
        "positive": "Energy conversion in Purple Bacteria Photosynthesis: The study of how photosynthetic organisms convert light offers insight not\nonly into nature's evolutionary process, but may also give clues as to how best\nto design and manipulate artificial photosynthetic systems -- and also how far\nwe can drive natural photosynthetic systems beyond normal operating conditions,\nso that they can harvest energy for us under otherwise extreme conditions. In\naddition to its interest from a basic scientific perspective, therefore, the\ngoal to develop a deep quantitative understanding of photosynthesis offers the\npotential payoff of enhancing our current arsenal of alternative energy sources\nfor the future.\n  In the following Chapter, we consider the trade-off between dynamics,\nstructure and function of light harvesting membranes in Rps. Photometricum\npurple bacteria, as a model to highlight the priorities that arise when\nphotosynthetic organisms adapt to deal with the ever-changing natural\nenvironment conditions."
    },
    {
        "anchor": "Interplay between microdynamics and macrorheology in vesicle suspensions: The microscopic dynamics of objects suspended in a fluid determines the\nmacroscopic rheology of a suspension. For example, as shown by Danker and\nMisbah [Phys. Rev. Lett. {\\bf 98}, 088104 (2007)], the viscosity of a dilute\nsuspension of fluid-filled vesicles is a non-monotonic function of the\nviscosity contrast (the ratio between the viscosities of the internal\nencapsulated and the external suspending fluids) and exhibits a minimum at the\ncritical point of the tank-treading-to-tumbling transition. By performing\nnumerical simulations, we recover this effect and demonstrate that it persists\nfor a wide range of vesicle parameters such as the concentration, membrane\ndeformability, or swelling degree. We also explain why other numerical and\nexperimental studies lead to contradicting results. Furthermore, our\nsimulations show that this effect even persists in non-dilute and confined\nsuspensions, but that it becomes less pronounced at higher concentrations and\nfor more swollen vesicles. For dense suspensions and for spherical (circular in\n2D) vesicles, the intrinsic viscosity tends to depend weakly on the viscosity\ncontrast.",
        "positive": "Phase behavior of binary mixtures of hard convex polyehdra: Shape anisotropy of colloidal nanoparticles has emerged as an important\ndesign variable for engineering assemblies with targeted structure and\nproperties. In particular, a number of polyhedral nanoparticles have been shown\nto exhibit a rich phase behavior [Agarwal et al., Nature Materials, 2011, 10,\n230]. Since real synthesized particles have polydispersity not only in size but\nalso in shape, we explore here the phase behavior of binary mixtures of hard\nconvex polyhedra having similar sizes but different shapes. Choosing\nrepresentative particle shapes from those readily synthesizable, we study in\nparticular four mixtures: (i) cubes and spheres (with spheres providing a\nnon-polyhedral reference case), (ii) cubes and truncated octahedra, (iii) cubes\nand cuboctahedra, and (iv) cuboctahedra and truncated octahedra. The phase\nbehavior of such mixtures is dependent on the interplay of mixing and packing\nentropy, which can give rise to miscible or phase-separated states. The extent\nof mixing of two such particle types is expected to depend on the degree of\nshape similarity, relative sizes, composition, and compatibility of the crystal\nstructures formed by the pure components. While expectedly the binary systems\nstudied exhibit phase separation at high pressures due to the incompatible\npure-component crystal structures, our study shows that the essential\nqualitative trends in miscibility and phase separation can be correlated to\nproperties of the pure components, such as the relative values of the\norder-disorder transition pressure (ODP) of each component. Specifically, if\nfor a mixture A+B we have that ODP_B <ODP_A and \\Delta ODP = ODP_A - ODP_B,\nthen at any particular pressure where phase separation occurs, the larger the\n\\Delta ODP the lower the solubility of A in the B-rich ordered phase and the\nhigher the solubility of B in the A-rich ordered phase."
    },
    {
        "anchor": "Phase transitions in a ferrofluid at magnetic field induced microphase\n  separation: In the presence of a magnetic field applied perpendicular to a thin sample\nlayer, a suspension of magnetic colloidal particles (ferrofluid) can form\nspatially modulated phases with a characteristic length determined by the\ncompetition between dipolar forces and short-range forces opposing density\nvariations. We introduce models for thin-film ferrofluids in which\nmagnetization and particle density are viewed as independent variables and in\nwhich the non-magnetic properties of the colloidal particles are described\neither by a lattice-gas entropy or by the Carnahan-Starling free energy. Our\ndescription is particularly well suited to the low-particle density regions\nstudied in many experiments. Within mean-field theory, we find isotropic,\nhexagonal and stripe phases, separated in general by first-order phase\nboundaries.",
        "positive": "Charge Renormalization and Charge Oscillation in Asymmetric Primitive\n  Model: The Debye charging method is generalized to study the linear response\nproperties of the asymmetric primitive model for electrolytes. Analytic results\nare obtained for the effective charge distributions of constituent ions inside\nthe electrolyte, from which all static linear response properties of system\nfollow. It is found that, as the ion density increases, both the screening\nlength and the dielectric constant receive substantial renormalization due to\nionic correlations. Furthermore, the valence of larger ion is substantially\nrenormalized upwards by ionic correlations, whilst that of smaller ions remains\napproximately the same. For sufficiently high density, the system exhibit\ncharge oscillations. The threshold ion density for charge oscillation is much\nlower than the corresponding value for symmetric electrolytes. Our results\nagree well with large scale Monte Carlo simulations."
    },
    {
        "anchor": "Effects of Ionic Strength on the Morphology, Scattering, and Mechanical\n  Response of Neurofilament-Derived Protein Brushes: Protein brushes not only play a key role in the functionality of\nneurofilaments but also have wide applications in biomedical materials. Here,\nwe investigate the effect of ionic strength on the morphology of protein\nbrushes using a continuous-space self-consistent field theory. A coarse-grained\nmulti-block charged macromolecular model is developed to capture the chemical\nidentity of amino acid sequences. For neurofilament heavy (NFH) brushes at pH\n2.4, we predict three morphological regimes: swollen brushes, condensed\nbrushes, and coexisting brushes which consist of both a dense inner layer and a\ndiffuse outer layer. The brush height predicted by our theory is in good\nagreement with experimental data for a wide range of ionic strengths. The\ndramatic height decrease is a result of the electrostatic screening-induced\ntransition from the overlapping state to the isolated state of the coexisting\nbrushes. We also study the evolution of the scattering and mechanical responses\naccompanying the morphological change. The oscillation in the reflectivity\nspectra characterizes the existence and microstructure of the inner condensed\nlayer, whereas the shoulder in the force spectra signifies the swollen\nmorphology.",
        "positive": "Generic transport coefficients of a confined electrolyte solution: Physical parameters characterising electrokinetic transport in a confined\nelectrolyte solution are reconstructed from the generic transport coefficients\nobtained within the classical non-equilibrium statistical thermodynamic\nframework. The electro-osmotic flow, the diffusio-osmotic flow, the osmotic\ncurrent, as well as the pressure-driven Poiseuille-type flow, the electric\nconduction, and the ion diffusion, are described by this set of transport\ncoefficients. The reconstruction is demonstrated for an aqueous NaCl solution\nbetween two parallel charged surfaces with a nanoscale gap, by using the\nmolecular dynamic (MD) simulations. A Green-Kubo approach is employed to\nevaluate the transport coefficients in the linear-response regime, and the\nfluxes induced by the pressure, electric, and chemical potential fields are\ncompared with the results of non-equilibrium MD simulations. Using this\nnumerical scheme, the influence of the salt concentration on the transport\ncoefficients is investigated. Anomalous reversal of diffusio-osmotic current,\nas well as that of electro-osmotic flow, is observed at high surface charge\ndensities and high added-salt concentrations."
    },
    {
        "anchor": "Contact network changes in ordered and disordered disk packings: We investigate the mechanical response of packings of purely repulsive,\nfrictionless disks to quasistatic deformations. The deformations include simple\nshear strain at constant packing fraction and at constant pressure,\n\"polydispersity\" strain (in which we change the particle size distribution) at\nconstant packing fraction and at constant pressure, and isotropic compression.\nFor each deformation, we show that there are two classes of changes in the\ninterparticle contact networks: jump changes and point changes. Jump changes\noccur when a contact network becomes mechanically unstable, particles\n\"rearrange\", and the potential energy (when the strain is applied at constant\npacking fraction) or enthalpy (when the strain is applied at constant pressure)\nand all derivatives are discontinuous. During point changes, a single contact\nis either added to or removed from the contact network. For repulsive linear\nspring interactions, second- and higher-order derivatives of the potential\nenergy/enthalpy are discontinuous at a point change, while for Hertzian\ninteractions, third- and higher-order derivatives of the potential\nenergy/enthalpy are discontinuous. We illustrate the importance of point\nchanges by studying the transition from a hexagonal crystal to a disordered\ncrystal induced by applying polydispersity strain. During this transition, the\nsystem only undergoes point changes, with no jump changes. We emphasize that\none must understand point changes, as well as jump changes, to predict the\nmechanical properties of jammed packings.",
        "positive": "Effects of Precursor Topology and Synthesis under Crowding Conditions on\n  the Structure of Single-Chain Polymer Nanoparticles: By means of molecular dynamics simulations we investigate the formation of\nsingle-chain nanoparticles through intramolecular cross-linking of polymer\nchains, in the presence of their precursors acting as purely steric crowders in\nconcentrated solution. In the case of the linear precursors, the structure of\nthe resulting SCNPs is weakly affected by the density at which the synthesis is\nperformed. Crowding has significant effects if ring precursors are used: higher\nconcentrations lead to the formation of SCNPs with more compact and spherical\nmorphologies. Such SCNPs retain in the swollen state (high dilution) the\ncrumpled globular conformations adopted by the ring precursors in the crowded\nsolutions. Increasing the concentration of both the linear and ring precursors\nup to $30 \\%$ leads to faster formation of the respective SCNPs."
    },
    {
        "anchor": "Interdiffusion of Solvent into Glassy Polymer Films: A Molecular\n  Dynamics Study: Large scale molecular dynamics and grand canonical Monte Carlo simulation\ntechniques are used to study the behavior of the interdiffusion of a solvent\ninto an entangled polymer matrix as the state of the polymer changes from a\nmelt to a glass. The weight gain by the polymer increases with time $t$ as\n$t^{1/2}$ in agreement with Fickian diffusion for all cases studied, although\nthe diffusivity is found to be strongly concentration dependent especially as\none approaches the glass transition temperature of the polymer. The diffusivity\nas a function of solvent concentration determined using the one-dimensional\nFick's model of the diffusion equation is compared to the diffusivity\ncalculated using the Darken equation from simulations of equilibrated\nsolvent-polymer solutions. The diffusivity calculated using these two different\napproaches are in good agreement. The behavior of the diffusivity strongly\ndepends on the state of the polymer and is related to the shape of the solvent\nconcentration profile.",
        "positive": "Interactions and design rules for assembly of porous colloidal\n  mesophases: Porous mesophases, where well-defined particle-depleted 'void' spaces are\npresent within a particle-rich background fluid, can be self-assembled from\ncolloidal particles interacting via isotropic pair interactions with competing\nattractions and repulsions. While such structures could be of wide interest for\ntechnological applications (e.g., filtration, catalysis, absorption, etc.),\nrelatively few studies have investigated the interactions that lead to these\nmorphologies and how they compare to those that produce other\nmicro-phase-separated structures, such as clusters. In this work, we use\ninverse methods of statistical mechanics to design model isotropic pair\npotentials that form porous mesophases. We characterize the resulting porous\nstructures, correlating features of the pair potential with the targeted pore\nsize and the particle packing fraction. The former is primarily encoded by the\namplitude and range of the repulsive barrier of the designed pair potential and\nthe latter by the attractive well depth. We observe a trade-off with respect to\nthe packing fraction of the targeted morphology: greater values support more\nspherical and monodisperse pores that themselves organize into periodic\nstructures, while lower values yield more mobile pores that do not assemble\ninto ordered structures but remain stable over a larger range of packing\nfraction. We conclude by commenting on the limitations of targeting a specific\npore diameter within the present inverse design approach as well as by\ndescribing future directions to overcome these limitations."
    },
    {
        "anchor": "Tensile Deformation and Failure of Thin Films of Aging Laponite\n  Suspension: In this paper we study deformation, failure and breakage of visco-elastic\nthin films of aging laponite suspension under tensile deformation field.\nAqueous suspension of laponite is known to undergo waiting time dependent\nevolution of its micro-structure, also known as aging, which is accompanied by\nan increase in the elastic modulus and relaxation time. In the velocity\ncontrolled tensile deformation experiments, we observed that the dependence of\nforce and dissipated energy on velocity and initial thickness of the film is\nintermediate to a Newtonian fluid and a yield stress fluid. For a fixed waiting\ntime, strain at break and dissipated energy increased with velocity, but\ndecreased with initial thickness. With increase in age, strain at break and\ndissipated energy showed a decrease suggesting enhanced brittle behavior with\nincrease in waiting time, which may be caused by restricted relaxation modes\ndue to aging. In a force controlled mode, decrease in strain at failure at\nhigher age also suggested enhanced brittleness with increase in waiting time.\nRemarkably, the constant force tensile deformation data up to the point of\nfailure showed experimental time- aging time superposition that gave an\nindependent estimation of relaxation time and elastic modulus dependence on\nage.",
        "positive": "Helices at Interfaces: Helically coiled filaments are a frequent motif in nature. In situations\ncommonly encountered in experiments coiled helices are squeezed flat onto two\ndimensional surfaces. Under such 2-D confinement helices form \"squeelices\" -\npeculiar squeezed conformations often resembling looped waves, spirals or\ncircles. Using theory and Monte-Carlo simulations we illuminate here the\nmechanics and the unusual statistical mechanics of confined helices and show\nthat their fluctuations can be understood in terms of moving and interacting\ndiscrete particle-like entities - the \"twist-kinks\". We show that confined\nfilaments can thermally switch between discrete topological twist quantized\nstates, with some of the states exhibiting dramatically enhanced\ncircularization probability while others displaying surprising\nhyperflexibility."
    },
    {
        "anchor": "Waves of DNA: Propagating Excitations in Extended Nanoconfined Polymers: We use a nanofluidic system to investigate the emergence of thermally driven\ncollective phenomena along a single polymer chain. In our approach, a single\nDNA molecule is confined in a nanofluidic slit etched with arrays of embedded\nnanocavities; the cavity lattice is designed so that a single chain occupies\nmultiple cavities. Fluorescent video-microscopy data shows that waves of excess\nfluorescence propagate across the cavity-straddling molecule, corresponding to\npropagating fluctuations of contour overdensity in the cavities. The waves are\nquantified by examining the correlation in intensity fluctuations between\nneighbouring cavities. Correlations grow from an anti-correlated minimum to a\ncorrelated maximum before decaying, corresponding to a transfer of contour\nbetween neighbouring cavities at a fixed transfer time-scale. The observed\ndynamics can be modelled using Langevin dynamics simulations and a minimal\nlattice model of coupled diffusion. This study shows how confinement-based\nsculpting of the polymer equilibrium configuration, by renormalizing the\nphysical system into a series of discrete cavity states, can lead to new types\nof dynamic collective phenomena.",
        "positive": "Tension dynamics in semiflexible polymers. Part I: Coarse-grained\n  equations of motion: Based on the wormlike chain model, a coarse-grained description of the\nnonlinear dynamics of a weakly bending semiflexible polymer is developed. By\nmeans of a multiple scale perturbation analysis, a length-scale separation\ninherent to the weakly-bending limit is exploited to reveal the deterministic\nnature of the spatio-temporal relaxation of the backbone tension and to deduce\nthe corresponding coarse-grained equation of motion. From this partial\nintegro-differential equation, some detailed analytical predictions for the\nnon-linear response of a weakly bending polymer are derived in an accompanying\npaper (Part II, cond-mat/0609638)."
    },
    {
        "anchor": "How geometric frustration shapes twisted fibers, inside and out:\n  Competing morphologies of chiral filament assembly: Chirality frustrates and shapes the assembly of flexible filaments in\nrope-like, twisted bundles and fibers by introducing gradients of both filament\nshape (i.e. curvature) and packing throughout the structure. Previous models of\nchiral filament bundle formation have shown that this frustration gives rise to\nseveral distinct morphological responses, including self-limiting bundle\nwidths, anisotropic domain (tape-like) formation and topological defects in the\nlateral inter-filament order. In this paper, we employ a combination of\ncontinuum elasticity theory and discrete filament bundle simulations to explore\nhow these distinct morphological responses compete in the broader phase diagram\nof chiral filament assembly. We show that the most generic model of bundle\nformation exhibits at least four classes of equilibrium structure --\nfinite-width, twisted bundles with isotropic and anisotropic shapes, with and\nwithout topological defects, as well as bulk phases of untwisted, columnar\nassembly (i.e. \"frustration escape\"). These competing equilibrium morphologies\nare selected by only a relatively small number of parameters describing\nfilament assembly: bundle surface energy, preferred chiral twist and stiffness\nof chiral filament interactions, and mechanical stiffness of filaments and\ntheir lateral interactions. Discrete filament bundle simulations test and\nverify continuum theory predictions for dependence of bundle structure (shape,\nsize and packing defects of 2D cross section) on these key parameters.",
        "positive": "Advanced multicanonical Monte Carlo methods for efficient simulations of\n  nucleation processes of polymers: The investigation of freezing transitions of single polymers is\ncomputationally demanding, since surface effects dominate the nucleation\nprocess. In recent studies we have systematically shown that the freezing\nproperties of flexible, elastic polymers depend on the precise chain length.\nPerforming multicanonical Monte Carlo simulations, we faced several\ncomputational challenges in connection with liquid-solid and solid-solid\ntransitions. For this reason, we developed novel methods and update strategies\nto overcome the arising problems. We introduce novel Monte Carlo moves and two\nextensions to the multicanonical method."
    },
    {
        "anchor": "Spinning motion of a deformable self-propelled particle in two\n  dimensions: We investigate the dynamics of a single deformable self-propelled particle\nwhich undergoes a spinning motion in a two-dimensional space. Equations of\nmotion are derived from the symmetry argument for three kinds of variables. One\nis a vector which represents the velocity of the centre of mass. The second is\na traceless symmetric tensor representing deformation. The third is an\nantisymmetric tensor for spinning degree of freedom. By numerical simulations,\nwe have obtained variety of dynamical states due to interplay between the\nspinning motion and the deformation. The bifurcations of these dynamical states\nare analyzed by the simplified equations of motion.",
        "positive": "Interfacial metric mechanics: stitching patterns of shape change in\n  active sheets: A flat sheet programmed with a planar pattern of spontaneous shape change\nwill morph into a curved surface. Such metric mechanics is seen in growing\nbiological sheets, and may be engineered in actuating soft matter sheets such\nas phase-changing liquid crystal elastomers (LCEs), swelling gels and inflating\nbaromorphs. Here, we show how to combine multiple patterns in a sheet by\nstitching regions of different shape changes together piecewise along\ninterfaces. This approach allows simple patterns to be used as building blocks,\nand enables the design of multi-material or active/passive sheets. We give a\ngeneral condition for an interface to be geometrically compatible, and explore\nits consequences for LCE/LCE, gel/gel, and active/passive interfaces. In\ncontraction/elongation systems such as LCEs, we find an infinite set of\ncompatible interfaces between any pair of patterns along which the metric is\ndiscontinuous, and a finite number across which the metric is continuous. As an\nexample, we find all possible interfaces between pairs of LCE logarithmic\nspiral patterns. In contrast, in isotropic systems such as swelling gels, only\na finite number of continuous interfaces are available, greatly limiting the\npotential of stitching. In both continuous and discontinuous cases, we find the\nstitched interfaces generically carry singular Gaussian curvature, leading to\nintrinsically curved folds in the actuated surface. We give a general\nexpression for the distribution of this curvature, and a more specialized form\nfor interfaces in LCE patterns. The interfaces thus also have rich geometric\nand mechanical properties in their own right."
    },
    {
        "anchor": "Granular impact cratering by liquid drops: Understanding raindrop\n  imprints through an analogy to asteroid strikes: When a granular material is impacted by a sphere, its surface deforms like a\nliquid yet it preserves a circular crater like a solid. Although the mechanism\nof granular impact cratering by solid spheres is well explored, our knowledge\non granular impact cratering by liquid drops is still very limited. Here, by\ncombining high-speed photography with high-precision laser profilometry, we\ninvestigate liquid-drop impact dynamics on granular surface and monitor the\nmorphology of resulting impact craters. Surprisingly, we find that, despite the\nenormous energy and length difference, granular impact cratering by liquid\ndrops follows the same energy scaling and reproduces the same crater morphology\nas that of asteroid impact craters. Inspired by this similarity, we integrate\nthe physical insight from planetary sciences, the liquid marble model from\nfluid mechanics and the concept of jamming transition from granular physics\ninto a simple theoretical framework that quantitatively describes all the main\nfeatures of liquid-drop imprints in granular media. Our study sheds light on\nthe mechanisms governing raindrop impacts on granular surfaces and reveals a\nremarkable analogy between familiar phenomena of raining and catastrophic\nasteroid strikes.",
        "positive": "Jamming in Systems With Quenched Disorder: We numerically study the effect of adding quenched disorder in the form of\nrandomly placed pinning sites on jamming transitions in systems that jam at a\nwell defined point J in the clean limit. Quenched disorder decreases the\njamming density and introduces a depinning threshold. The onset of a finite\nthreshold coincides with point J at the lowest pinning densities, but for\nhigher pinning densities there is always a finite threshold even well below\njamming. We find that proximity to point J strongly affects the transport\ncurves and noise fluctuations, and observe a change from plastic behavior below\njamming, where the system is highly heterogeneous, to elastic depinning above\njamming. Many of the general features we find are related to other systems\ncontaining quenched disorder, including the peak effect observed in vortex\nsystems."
    },
    {
        "anchor": "A New Drop Fluidics Enabled by Magnetic Field Mediated Elasto-Capillary\n  Transduction: This research introduces a new drop fluidics, which uses a deformable and\nstretchable elastomeric film as the platform, instead of the commonly used\nrigid supports. Such a soft film impregnated with magnetic particles can be\nmodulated with an external electromagnetic field that produces a vast array of\ntopographical landscapes with varying surface curvature, which, in conjunction\nwith capillarity, can direct and control motion of water droplets efficiently\nand accurately. When a thin layer of oil is present on this film that is\ndeformed locally, a centrosymmetric wedge is formed. A water droplet placed on\nthis oil laden film becomes asymmetrically deformed thus producing a gradient\nof Laplace pressure within the droplet setting it to motion. A simple theory is\npresented that accounts for the droplet speed in terms of such geometric\nvariables as the volume of the droplet and the thickness of the oil film\ncovering the soft elastomeric film, as well as such material variables as the\nviscosity of the oil and interfacial tension of the oil-water interfaces.\nFollowing the verification of the theoretical result using well-controlled\nmodel systems, we demonstrate how the electromagnetically controlled\nelasto-capillary force can be used to manipulate the motion of single and/or\nmultiple droplets on the surface of the elastomeric film and how such\nelementary operations as drop fusion and thermally addressed chemical\ntransformation can be carried out in aqueous droplets. It is expected that the\nresulting drop fluidics would be suitable for digital control of drop motion by\nsimply switching on and off the electromagnetic fields applied at different\npositions underneath the elastomeric film. We anticipate that this method of\ndirecting and manipulating water droplets is poised for its applications in\nvarious biochemical reaction engineering, an example of which is Polymerase\nChain Reaction (PCR).",
        "positive": "Perturbative density functional methods for cholesteric liquid crystals: We introduce a comprehensive numerical framework to generically infer the\nemergent macroscopic properties of uniaxial nematic and cholesteric phases from\nthat of their microscopic constituent mesogens. This approach, based on the\nfull numerical resolution of the Poniewierski-Stecki equations in the weak\nchirality limit, may expediently handle a wide range of particle models through\nthe use of Monte-Carlo sampling for all virial-type integrals. Its predictions\nin terms of equilibrium cholesteric structures are found to be in excellent\nagreement with previous full-functional descriptions, thereby demonstrating the\nquantitative validity of the perturbative treatment of chirality for pitch\nlengths as short as a few dozen particle diameters. Furthermore, the use of the\nfull angle-dependent virial coefficients in the Onsager-Parsons-Lee formalism\nincreases its numerical efficiency by several orders of magnitude over that of\nthese previous methods. The comparison of our results with numerical\nsimulations however reveals some shortcomings of the Parsons-Lee approximation\nfor systems of strongly non-convex particles, notwithstanding the accurate\ninclusion of their full effective molecular volume. Further potential\nlimitations of our theory in terms of phase symmetry assumptions are also\nexamined, and prospective directions for future improvements discussed."
    },
    {
        "anchor": "Surface tension of membranes depending on the boundary shape: In this paper, we study the boundary effect on the surface (or frame) tension\nof elastic membrane surface models. The frame tension generally depends only on\nthe projected area of the boundary over which the surface spans. However, from\na spin model analogy, the frame tension is expected to be dependent also on the\nboundary shape at the continuous transition point. We confirm this expectation\nusing the following fixed-connectivity and tethered surface models: the surface\nmodel of Helfrich and Polyakov and a surface model with deficit angle term. We\nalso discuss the reason why this expectation is worthwhile to study.",
        "positive": "Static and Dynamic Properties of Block-Copolymer Based Grafted\n  Nanoparticles Across the Non-Ergodicity Transition: We present a systematic investigation of static and dynamic properties of\nblock copolymer micelles with crosslinked cores, representing model\npolymer-grafted nanoparticles, over a wide concentration range from dilute\nregime to an arrested (crystalline) state, by means of light and neutron\nscattering, complemented by linear viscoelasticity. We have followed the\nevolution of their scattering intensity and diffusion dynamics throughout the\nnon-ergodicity transition and the observed results have been contrasted against\nappropriately coarse-grained Langevin Dynamics simulations. These stable model\nsoft particles of the core-shell type are situated between ultrasoft stars and\nhard spheres, and the well-known star pair interaction potential is not\nappropriate to describe them. Instead, we have found that an effective brush\ninteraction potential provides very satisfactory agreement between experiments\nand simulations, offering insights into the interplay of softness and dynamics\nin spherical colloidal suspensions."
    },
    {
        "anchor": "Fluctuations and Defects in Lamellar Stacks of Amphiphilic Bilayers: We review recent molecular dynamics simulations of thermally activated\nundulations and defects in the lamellar $L_\\alpha$ phase of a binary\namphiphile-solvent mixture, using an idealized molecular coarse-grained model:\nSolvent particles are represented by beads, and amphiphiles by bead-and-spring\ntetramers. We find that our results are in excellent agreement with the\npredictions of simple mesoscopic theories: An effective interface model for the\nundulations, and a line tension model for the (pore) defects. We calculate the\nbinding rigidity and the compressibility modulus of the lamellar stack as well\nas the line tension of the pore rim. Finally, we discuss implications for\npolymer-membrane systems.",
        "positive": "Dynamic buckling of elastic rings in a soap film: Dynamic buckling may occur when a load is rapidly applied to, or removed\nfrom, an elastic object at rest. In contrast to its static counterpart, dynamic\nbuckling offers a wide range of accessible patterns depending on the parameters\nof the system and the dynamics of the load. To study these effects, we consider\nexperimentally the dynamics of an elastic ring in a soap film when part of the\nfilm is suddenly removed. The resulting change in tension applied to the ring\ncreates a range of interesting patterns that cannot be easily accessed in\nstatic experiments. Depending on the aspect ratio of the ring's cross section,\nhigh-mode buckling patterns are found in the plane of the remaining soap film\nor out of the plane. Paradoxically, while inertia is required to observe these\nnon-trivial modes, the selected pattern does not depend on inertia itself. The\nevolution of this pattern beyond the initial instability is studied\nexperimentally and explained through theoretical arguments linking dynamics to\npattern selection and mode growth. We also explore the influence of dynamic\nloading and show numerically that by imposing a rate of loading that competes\nwith the growth rate of instability, the observed pattern can be selected and\ncontrolled."
    },
    {
        "anchor": "An experimental study of morphological formation in bilayered tubular\n  structures driven by swelling/growth: This paper presents an experimental investigation on pattern formation and\nevolution in bilayered tubular organs using swelling deformation of\npolydimethylsiloxane (PDMS) and aims at supplying a thorough comparison with\ntheoretical and finite element results. To create a twin model in modelling and\nsimulation, the shear modulus in the incompressible neo-Hookean material is\nestimated via uni-axial tensile and pure shear tests. Five bilayered tubes with\ndifferent material or geometrical parameters are fabricated. Swelling\nexperiments are carried out for these samples in an individual experimental\nsetup where a plane-strain deformation is guaranteed, and several surface\npatterns and the associated mode transformations are observed, namely, creases,\nwrinkles, period-doubling profiles, wrinkle-to-crease transition, and\nwrinkle-to-period-doubling transition. In particular, an interfacial wrinkling\npattern is also observed. To make comparisons, a buckling analysis is conducted\nwithin the framework of finite elasticity by means of the Stroh formulation. In\naddition, a finite element analysis is performed to trace the evolution of\nsurface instabilities. It turns out that the experimental findings agree well\nwith the theoretical predictions as well as the finite element results. From\nour experiments, it is found that creasing mode may appear instead of wrinkling\nmode when both layers share a similar mechanical property. It is expected that\nthe current work could provide novel experimental insight into pattern\nformation in tubular structures, and the good agreement among experimental,\ntheoretical, and simulation consequences supplies strong evidence that a\nphenomenological growth model is satisfactory to reveal mechanisms behind\nintricate surface morphology in tubular tissues.",
        "positive": "Real-time characterization of the mechanical behaviour of an actively\n  growing bacterial culture by rheology: The population growth of a Staphylococcus aureus culture was followed by\nrheological measurements, under steady-state and dynamic shear flows. We\nobserved a rich viscoelastic behaviour as a consequence of the bacteria\nactivity. First, the viscosity increased ~10 times due to cell multiplication\nand aggregation. This viscosity increase presented several drops and full\nrecoveries, which are reproducible, allowing us to evoke the existence of a\npercolation phenomenon. Eventually, as the bacteria population reached a final\nstage of development, fulfilling the sample volume, the viscosity returned to\nits initial value, most probably caused by a change in the bacteria\nphysiological activity, in particular the decrease of their adhesion\nproperties. Finally, the viscous and the elastic moduli presented power law\nbehaviours compatible with the \"soft glassy materials\" model, which exponents\nare dependent on the bacteria growth stage."
    },
    {
        "anchor": "A Lattice Boltzmann study of flow along patterned surfaces and through\n  channels with alternating slip length: In microfluidics, varying wetting properties, expressed in terms of the local\nslip length, can be used to influence the flow of a liquid through a device. We\nstudy flow past surfaces on which the slip length is modulated in stripes. We\nfind that the effective slip length for such a flow can be expressed as a\nfunction of the individual slip lengths on the stripes. The angle dependence of\nthe effective slip is in excellent agreement with a recent theory describing\nthe slip length as a tensorial quantity. This tensorial nature allows to induce\na transverse flow, which can be used in micro mixers to drive a vortex. In our\nsimulations of a flow through a square channel with patterned surfaces we see a\nhomogeneous rotation about the direction of the flow. We investigate the\ninfluence of patterns of cosine shaped varying local slip on the flow field\ndepending on the orientation of the pattern and find the largest effective slip\nlength for periods of stripes parallel to the flow direction.",
        "positive": "Affinity, Kinetics, and Pathways of Anisotropic Ligands Binding to\n  Hydrophobic Model Pockets: Using explicit-water molecular dynamics (MD) simulations of a generic\npocket-ligand model we investigate how chemical and shape anisotropy of small\nligands influences the affinities, kinetic rates and pathways for their\nassociation to hydrophobic binding sites. In particular, we investigate\naromatic compounds, all of similar molecular size, but distinct by various\nhydrophilic or hydrophobic residues. We demonstrate that the most hydrophobic\nsections are in general desolvated primarily upon binding to the cavity,\nsuggesting that specific hydration of the different chemical units can steer\nthe orientation pathways via a `hydrophobic torque'. Moreover, we find that\nligands with bimodal orientation fluctuations have significantly increased\nkinetic barriers for binding compared to the kinetic barriers previously\nobserved for spherical ligands due to translational fluctuations. We exemplify\nthat these kinetic barriers, which are ligand specific, impact both binding and\nunbinding times for which we observe considerable differences between our\nstudied ligands."
    },
    {
        "anchor": "Designing Pairwise Interactions that Stabilize Open Crystals: Truncated\n  Square and Truncated Hexagonal Lattices: Using a recently introduced formulation of the ground-state inverse design\nproblem for a targeted lattice [Pi\\~neros et al., J. Chem. Phys. 144} 084502\n(2016)], we discover purely repulsive and isotropic pair interactions that\nstabilize low-density truncated square and truncated hexagonal crystals, as\nwell as promote their assembly in Monte Carlo simulations upon isochoric\ncooling from a high-temperature fluid phase. The results illustrate that the\nprimary challenge to stabilizing very open two-dimensional lattices is to\ndesign interactions that can favor the target structure over competing stripe\nmicrophases.",
        "positive": "Influence of nanoparticle size, loading, and shape on the mechanical\n  properties of polymer nanocomposites: We study the influence of spherical, triangular, and rod-like nanoparticles\non the mechanical properties of a polymer nanocomposite (PNC), via\ncoarse-grained molecular dynamics simulations. We focus on how the nanoparticle\nsize, loading, mass, and shape influence the PNC's elastic modulus, stress at\nfailure and resistance against cavity formation and growth, under external\nstress. We find that in the regime of strong polymer-nanoparticle interactions,\nthe formation of a polymer network via temporary polymer-nanoparticle\ncrosslinks has a predominant role on the PNC reinforcement. Spherical\nnanoparticles, whose size is comparable to that of the polymer monomers, are\nmore effective at toughening the PNC than larger spherical particles. When\ncomparing particles of spherical, triangular, and rod-like geometries, the\nrod-like nanoparticles emerge as the best PNC toughening agents."
    },
    {
        "anchor": "Time-Asymmetric Fluctuation Theorem and Efficient Free Energy Estimation: The free-energy difference $\\Delta F$ between two high-dimensional systems is\nnotoriously difficult to compute, but very important for many applications,\nsuch as drug discovery. We demonstrate that an unconventional definition of\nwork introduced by Vaikuntanathan and Jarzynski (2008) satisfies a microscopic\nfluctuation theorem that relates path ensembles that are driven by protocols\nunequal under time-reversal. It has been shown before that counterdiabatic\nprotocols -- those having additional forcing that enforces the system to remain\nin instantaneous equilibrium, also known as escorted dynamics or engineered\nswift equilibration -- yield zero-variance work measurements for this\ndefinition. We show that this time-asymmetric microscopic fluctuation theorem\ncan be exploited for efficient free energy estimation by developing a simple\n(i.e., neural-network free) and efficient adaptive time-asymmetric protocol\noptimization algorithm that yields $\\Delta F$ estimates that are orders of\nmagnitude lower in mean squared error than the generic linear interpolation\nprotocol with which it is initialized.",
        "positive": "The $(2+\u03b4)$-dimensional theory of the electromechanics of lipid\n  membranes: II. Balance laws: This article is the second of a three-part series that derives a\nself-consistent theoretical framework of the electromechanics of arbitrarily\ncurved lipid membranes. Existing continuum theories commonly treat lipid\nmembranes as strictly two-dimensional surfaces. While this approach is\nsuccessful in many purely mechanical applications, strict surface theories fail\nto capture the electric potential drop across lipid membranes, the effects of\nsurface charges, and electric fields within the membrane. Consequently, they do\nnot accurately resolve Maxwell stresses in the interior of the membrane and its\nproximity. Furthermore, surface theories are generally unable to capture the\neffects of distinct velocities and tractions at the interfaces between lipid\nmembranes and their surrounding bulk fluids. To address these shortcomings, we\napply a recently proposed dimension reduction method to the three-dimensional,\nelectromechanical balance laws. This approach allows us to derive an effective\nsurface theory without taking the limit of vanishing thickness, thus\nincorporating effects arising from the finite thickness of lipid membranes. We\nrefer to this effective surface theory as $(2 + \\delta)$-dimensional, where\n$\\delta$ indicates the thickness. The resulting $(2 + \\delta)$-dimensional\nequations of motion satisfy velocity and traction continuity conditions at the\nmembrane-bulk interfaces, capture the effects of Maxwell stresses, and can\ndirectly incorporate three-dimensional constitutive models."
    },
    {
        "anchor": "Effect of substrate topography, material wettability and dielectric\n  thickness on reversible electrowetting: Recent experiments by Kavousanakis et al., Langmuir, 2018 [1], showed that\nreversible electrowetting on superhydrophobic surfaces can be achieved by using\na thick solid dielectric layer (e.g. tens of micrometers). It has also been\nshown, through equilibrium (static) computations, that when the dielectric\nlayer is thick enough the electrostatic pressure is smoothly distributed along\nthe droplet surface, thus the irreversible Cassie to Wenzel wetting transitions\ncan be prevented. In the present work we perform more realistic, dynamic\nsimulations of the electrostatically-induced spreading on superhydrophobic\nsurfaces. To this end, we employ an efficient numerical scheme which enables us\nto fully take into account the topography of the solid substrate. We\ninvestigate in detail the role of the various characteristics of the substrate\n(i.e. the dielectric thickness, geometry and material wettability) and present\nrelevant flow maps for the resulting wetting states. Through our dynamic\nsimulations, we identify the conditions under which it is possible to achieve\nreversible electrowetting. We have found that not only the collapse\n(Cassie-Baxter to Wenzel) transitions but also the contact angle hysteresis of\nthe substrate significantly affects the reversibility.",
        "positive": "Evidence of Epitaxial Growth of Molecular Layers of Dissolved Gas at a\n  Hydrophobic/Water Interface: The non-wetting phenomena of water on certain solid surfaces have been under\nintensive study for decades, but the nature of hydrophobic/water interfaces\nremains controversial. Here a water/graphite interface is investigated with\nhigh-sensitivity atomic force microscopy. We show evidence of nucleation and\ngrowth of an epitaxial monolayer on the graphite surface, probably caused by\nadsorption of nitrogen molecules dissolved in water. The subsequent adsorption\nprocess resembles the layer-plus-island, or Stranski-Krastanov, growth mode in\nheteroepitaxy. This finding underlines the importance of gas segregation at\nvarious water interfaces and may unravel many puzzles, especially the nature\nand the high stability of so-called nanobubbles at solid/water interfaces and\nin bulk water. Based on the hydrophobic effect, we propose that gas molecules\ndissolved in water may aggregate into clusters in bulk water as well as at\nsolid/water interfaces. As a cluster grows above a critical size, it undergoes\na transition into a gas bubble, which can explain formation or nucleation of\ngas bubbles in water."
    },
    {
        "anchor": "Dynamic light scattering from colloidal fractal monolayers: We address experimentally the problem of how the structure of a surface\nmonolayer determines the visco-elasticity of the interface. Optical microscopy\nand surface quasi--elastic light scattering have been used to characterize\naggregation of CaCO$_3$ particles at the air--water interface. The structures\nformed by cluster-cluster aggregation are two dimensional fractals which grow\nto eventually form a percolating network. This process is measured through\nimage analysis. On the same system we measure the dynamics of interfacial\nthermal fluctuations (surface ripplons), and we discuss how the relaxation\nprocess is affected by the growing clusters. We show that the structures start\ndamping the ripplons strongly when the two length scales are comparable. No\nmacroscopic surface pressure is measured and this is in contrast to lipid,\nsurfactant or polymer monolayers at concentrations corresponding to surface\ncoverage. This observation and the difficulty in fitting the ripplon spectrum\nwith traditional models suggest that a different physical mechanism might be\nresponsible for the observed damping of ripplons in this system.",
        "positive": "A nonlinear hydrodynamical approach to granular materials: We propose a nonlinear hydrodynamical model of granular materials. We show\nhow this model describes the formation of a sand pile from a homogeneous\ndistribution of material under gravity, and then discuss a simulation of a\nrotating sandpile which shows, in qualitative agreement with experiment, a\nstatic and dynamic angle of repose."
    },
    {
        "anchor": "Local Segmental Dynamics and Stresses in Polystyrene - C$_{60}$ Mixtures: The polymer dynamics of homogeneous C$_{60}$-polystyrene mixtures in the\nmolten state are studied via molecular simulations using two interconnected\nlevels of representation for polystyrene nanocomposites: (a) A coarse-grained\nrepresentation, in which each polystyrene repeat unit is mapped into a single\n\"superatom\" and each fullerene is viewed as a spherical shell. Equilibration of\ncoarse-grained polymer-nanoparticle systems at all length scales is achieved\nvia connectivity-altering Monte Carlo simulations. (b) An atomistic\nrepresentation, where both nanoparticles and polymer chains are represented in\nterms of united-atom forcefields. Initial configurations for atomistic\nMolecular Dynamics (MD) simulations are obtained by reverse mapping\nwell-equilibrated coarse-grained configurations. By analyzing MD trajectories\nunder constant energy, the segmental dynamics of polystyrene (for neat and\nfilled systems) is characterized in terms of bond orientation time\nautocorrelation functions. Nanocomposite systems are found to exhibit slightly\nslower segmental dynamics than the unfilled ones, in good agreement with\navailable experimental data. Moreover, by employing Voronoi tessellation of the\nsimulation box, the mean-squared displacement of backbone carbon atoms is\nquantified in the vicinity of each fullerene molecule. Fullerenes are found to\nsuppress the average motion of polymeric chains, in agreement with neutron\nscattering data, while slightly increasing the dynamic and stress heterogeneity\nof the melt. Atomic-level and local (per Voronoi cell) stress distributions are\nreported for the pure and the filled systems.",
        "positive": "Active Ornstein-Uhlenbeck particles: Active Ornstein-Uhlenbeck particles (AOUPs) are overdamped particles in an\ninteraction potential subject to external Ornstein-Uhlenbeck noises. They can\nbe transformed into a system of underdamped particles under additional velocity\ndependent forces and subject to white noise forces. There has been some\ndiscussion in the literature on whether AOUPs can be in equilibrium for\nparticular interaction potentials and how far from equilibrium they are in the\nlimit of small persistence time. By using a theorem on the time reversed form\nof the AOUP Langevin-Ito equations, I prove that they have an equilibrium\nprobability density invariant under time reversal if and only if their smooth\ninteraction potential has zero third derivatives. In the limit of small\npersistence Ornstein-Uhlenbeck time $\\tau$, a Chapman-Enskog expansion of the\nFokker-Planck equation shows that the probability density has a local\nequilibrium solution in the particle momenta modulated by a reduced probability\ndensity that varies slowly with the position. The reduced probability density\nsatisfies a continuity equation in which the probability current has an\nasymptotic expansion in powers of $\\tau$. Keeping up to $O(\\tau)$ terms, this\nequation is a diffusion equation, which has an equilibrium stationary solution\nwith zero current. However, $O(\\tau^2)$ terms contain fifth and sixth order\nspatial derivatives and the continuity equation no longer has a zero current\nstationary solution. The expansion of the overall stationary solution now\ncontains odd terms in the momenta, which clearly shows that it is not an\nequilibrium."
    },
    {
        "anchor": "Self-assembly of spherical interpolyelectrolyte complexes from\n  oppositely charged polymers: The formation of inter-polyelectrolyte complexes from the association of\noppositely charged polymers in an electrolyte is studied. The charged polymers\nare linear oppositely charged polyelectrolytes, with possibly a neutral block.\nThis leads to complexes with a charged core, and a more dilute corona of\ndangling chains, or of loops (flower-like structure). The equilibrium\naggregation number of the complexes (number of polycations m+ and polyanions\nm-) is determined by minimizing the relevant free energy functional, the\nCoulombic contribution of which is worked out within Poisson-Boltzmann theory.\nThe complexes can be viewed as colloids that are permeable to micro-ionic\nspecies, including salt. We find that the complexation process can be highly\nspecific, giving rise to very localized size distribution in composition space\n(m+,m-).",
        "positive": "Light-activated microtubule-based 2D active nematic: We characterize two-dimensional (2D) microtubule-based active nematics driven\nby light-responsive kinesin motor clusters. We assess two constructs of\noptogenetic kinesin: opto-K401, a processive motor, and opto-K365, a\nnon-processive motor. Measurements reveal an order of magnitude improvement in\nthe contrast of nematic flow speeds between maximally- and\nminimally-illuminated states for opto-K365 motors. Focusing on opto-K365\nnematics, we characterize both the steady-state flow and defect density as a\nfunction of applied light and examine the transient behavior between\nsteady-states. The steady-state nematic flow and defect densities are set by\nthe applied light intensity across centimeter-sized samples, independent of\ninitial conditions. Although nematic flow reaches steady-state within tens of\nseconds, the defect density exhibits transient behavior for 4 to 10 minutes,\nshowing a separation between small-scale active reorganization and system-scale\nstructural states. This work establishes an experimental platform to test\ntheoretical frameworks which exploit spatiotemporally-heterogeneous patterns of\nactivity to generate targeted dynamical states."
    },
    {
        "anchor": "DNA hybridization kinetics: zippering, internal displacement and\n  sequence dependence: While the thermodynamics of DNA hybridization is well understood, much less\nis known about the kinetics of this classic system. Filling this gap in our\nunderstanding has new urgency because DNA nanotechnology often depends\ncritically on binding rates. Here we use a coarse-grained model to explore the\nhybridization kinetics of DNA oligomers, finding that strand association\nproceeds through a complex set of intermediate states. Successful binding\nevents start with the formation of a few metastable base-pairing interactions,\nfollowed by zippering of the remaining bonds. However, despite reasonably\nstrong interstrand interactions, initial contacts frequently fail to lead to\nzippering because the typical configurations in which they form differ from\ntypical states of similar enthalpy in the double-stranded equilibrium ensemble.\nTherefore, if the association process is analyzed on the base-pair (secondary\nstructure) level, it shows non-Markovian behavior. Initial contacts must be\nstabilized by two or three base pairs before full zippering is likely,\nresulting in negative effective activation enthalpies. Non-Arrhenius behavior\nis observed as the number of base pairs in the effective transition state\nincreases with temperature. In addition, we find that alternative pathways\ninvolving misbonds can increase association rates. For repetitive sequences,\nmisaligned duplexes frequently rearrange to form fully paired duplexes by two\ndistinct processes which we label `pseudoknot' and `inchworm' internal\ndisplacement. We show how the above processes can explain why experimentally\nobserved association rates of GC-rich oligomers are higher than rates of\nAT-rich equivalents. More generally, we argue that association rates can be\nmodulated by sequence choice.",
        "positive": "Discontinuous Meniscus Location in Tapered Capillaries Driven by\n  Pressure Difference and Dielectrophoretic Forces: We calculate the meniscus location in tapered capillaries under the influence\nof pressure difference and dielectrophoretic forces with and without gravity.\nWe find that the meniscus location can be a discontinuous function of the\npressure difference or the applied voltage and that the meniscus can ``jump''\nto one end or another of the capillary. Phase diagrams are given as a function\nof the pressure and voltage, depending on the geometrical parameters of the\nsystem. We further consider a revision of the dielectric rise under\ndielectrophoretic force in wedge capillaries and in the case of electrowetting,\nwhere the dielectrophoretic force is a small perturbation. Finally, we also\nfind discontinuous liquid--gas interface location in the case of liquid\npenetration into closed volumes."
    },
    {
        "anchor": "Modeling tensorial conductivity of particle suspension networks: Significant microstructural anisotropy is known to develop during shearing\nflow of attractive particle suspensions. These suspensions, and their capacity\nto form conductive networks, play a key role in flow-battery technology, among\nother applications. Herein, we present and test an analytical model for the\ntensorial conductivity of attractive particle suspensions. The model utilizes\nthe mean fabric of the network to characterize the structure, and the\nrelationship to the conductivity is inspired by a lattice argument. We test the\naccuracy of our model against a large number of computer-generated suspension\nnetworks, based on multiple in-house generation protocols, giving rise to\nparticle networks that emulate the physical system. The model is shown to\nadequately capture the tensorial conductivity, both in terms of its invariants\nand its mean directionality.",
        "positive": "Entanglements in a Quiescent and Sheared Polymer Melt: Molecular dynamics simulations were performed for a polymer melt. In\nquiescent states, the inter-chain interaction energy supported by each particle\ntakes relatively large values persistently for long times if the particle is\nclose to an entanglement. Thus, if the interaction is averaged over appropriate\ntime intervals, we can detect active spots on the chains produced by\nentanglement constrains. If rapid shearing is applied, these active regions\nsubsequently become bended in eventual zig-zag shapes of the chains. We also\ndemonstrate that stress overshoot occurs with onset of disentanglement."
    },
    {
        "anchor": "Hydrodynamic Burnett equations for inelastic Maxwell models of granular\n  gases: The hydrodynamic Burnett equations and the associated transport coefficients\nare exactly evaluated for generalized inelastic Maxwell models. In those\nmodels, the one-particle distribution function obeys the inelastic Boltzmann\nequation, with a velocity-independent collision rate proportional to the\n$\\gamma$ power of the temperature. The pressure tensor and the heat flux are\nobtained to second order in the spatial gradients of the hydrodynamic fields\nwith explicit expressions for all the Burnett transport coefficients as\nfunctions of $\\gamma$, the coefficient of normal restitution, and the\ndimensionality of the system. Some transport coefficients that are related in a\nsimple way in the elastic limit become decoupled in the inelastic case. As a\nbyproduct, existing results in the literature for three-dimensional elastic\nsystems are recovered, and a generalization to any dimension of the system is\ngiven. The structure of the present results is used to estimate the Burnett\ncoefficients for inelastic hard spheres.",
        "positive": "Dynamical density functional theory for the diffusion of injected\n  Brownian particles: While the theory of diffusion of a single Brownian particle in confined\ngeometries is well-established by now, we discuss here the theoretical\nframework necessary to generalize the theory of diffusion to dense suspensions\nof strongly interacting Brownian particles. Dynamical density functional theory\n(DDFT) for classical Brownian particles represents an ideal tool for this\npurpose. After outlining the basic ingredients to DDFT we show that it can be\nreadily applied to flowing suspensions with time-dependent particle sources.\nParticle interactions lead to considerable layering in the mean density\nprofiles, a feature that is absent in the trivial case of noninteracting,\nfreely diffusing particles. If the particle injection rate varies periodically\nin time with a suitable frequency, a resonance in the layering of the mean\nparticle density profile is predicted."
    },
    {
        "anchor": "Universality in the diffusion of knots: We have evaluated a universal ratio between diffusion constants of the ring\npolymer with a given knot $K$ and a linear polymer with the same molecular\nweight in solution through the Brownian dynamics under hydrodynamic\ninteraction. The ratio is found to be constant with respect to the number of\nmonomers, $N$, and hence the estimate at some $N$ should be valid practically\nover a wide range of $N$ for various polymer models. Interestingly, the ratio\nis determined by the average crossing number ($N_{AC}$) of an ideal\nconformation of knotted curve $K$, i.e. that of the ideal knot. The $N_{AC}$ of\nideal knots should therefore be fundamental in the dynamics of knots.",
        "positive": "Charge Fluctuations on Membrane Surfaces in Water: We generalize the predictions for attractions between over-all neutral\nsurfaces induced by charge fluctuations/correlations to non-uniform systems\nthat include dielectric discontinuities, as is the case for mixed charged lipid\nmembranes in an aqueous solution. We show that the induced interactions depend\nin a non-trivial way on the dielectric constants of membrane and water and show\ndifferent scaling with distance depending on these properties. The generality\nof the calculations also allows us to predict under which dielectric conditions\nthe interaction will change sign and become repulsive."
    },
    {
        "anchor": "Why is the DNA Denaturation Transition First Order?: We study a model for the denaturation transition of DNA in which the\nmolecules are considered as composed of a sequence of alternating bound\nsegments and denaturated loops. We take into account the excluded-volume\ninteractions between denaturated loops and the rest of the chain by exploiting\nrecent results on scaling properties of polymer networks of arbitrary topology.\nThe phase transition is found to be first order in d=2 dimensions and above, in\nagreement with experiments and at variance with previous theoretical results,\nin which only excluded-volume interactions within denaturated loops were taken\ninto account. Our results agree with recent numerical simulations.",
        "positive": "Side-leakage of facemask: Face masks are used to trap particles (or fluid drops) in a porous material\n(filter) in order to avoid or reduce the transfer of particles between the\nhuman lungs (or mouth and nose) and the external environment. The air exchange\nbetween the lungs and the environment is assumed to occur through the facemask\nfilter. However, if the resistance to air flow through the filter is high some\nair (and accompanied particles) will leak through the filter-skin interface. In\nthis paper I will present a model study of the side-leakage problem."
    },
    {
        "anchor": "The Rouse-Zimm-Brinkman theory of the dynamics of polymers in dilute\n  solutions: We propose a theory of the dynamics of polymers in dilute solution, in which\nthe popular Zimm and Rouse models are limiting cases of infinitely large and\nsmall draining parameter. The equation of motion for the polymer segments\nbeads) is solved together with Brinkman's equation for the solvent velocity\nthat takes into account the presence of other polymer coils in the solution.\nThe equation for the polymer normal modes is obtained and the relevant time\ncorrelation functions are found. A tendency to the time-dependent hydrodynamic\nscreening is demonstrated on the diffusion of the polymers as well as on the\nrelaxation of their internal modes. With the growing concentration of the coils\nin solution they both show a transition to the (exactly) Rouse behavior. The\nshear viscosity of the solution, the Huggins coefficient and other quantities\nare calculated and shown to be notably different from the known results.",
        "positive": "The Structural Origin of Enhanced Dynamics at the Surface of a Glassy\n  Alloy: The enhancement of mobility at the surface of an amorphous alloy is studied\nusing a combination of molecular dynamic simulations and normal mode analysis\nof the non-uniform distribution of Debye-Waller factors. The increased mobility\nat the surface is found to be associated with the appearance of Arrhenius\ntemperature dependence. We show that the transverse Debye-Waller factor\nexhibits a peak at the surface. Over the accessible temperature range, we find\nthat the bulk and surface diffusion coefficients obey the same empirical\nrelationship with the respective Debye-Waller factors. Extrapolating this\nrelationship to lower T, we argue that the observed decrease in the constraint\nat the surface is sufficient to account for the experimentally observed surface\nenhancement of mobility."
    },
    {
        "anchor": "Lyotropic Lamellar Phase Doped with a Nematic Phase of Magnetic Nanorods: We report the elaboration of a hybrid mesophase combining the lamellar order\nof a lyotropic system of nonionic surfactant and the nematic order of a\nconcentrated solution of inorganic nanorods confined between the surfactant\nlayers. Highly aligned samples of this mesophase can be obtained by thermal\nannealing, and the orientation of the nanorods is readily controlled with a\nmagnetic field. High-resolution synchrotron X-ray scattering and polarized\noptical microscopy show that, compared to their isolated counterparts, both the\nnematic and lamellar orders are altered, demonstrating their interplay.",
        "positive": "Self-diffusion in single-component Yukawa fluids: It was suggested in the literature that the self-diffusion coefficient of\nsimple fluids can be approximated as a ratio of the squared thermal velocity of\nthe atoms to the \"fluid Einstein frequency,\" which can thus serve as a rough\nestimate of the friction (momentum transfer) rate in the dense fluid phase. In\nthis article we test this suggestion using a single-component Yukawa fluid as a\nreference system. The available simulation data on self-diffusion in Yukawa\nfluids, complemented with new data for Yukawa melts (Yukawa fluids near the\nfreezing phase transition), are carefully analyzed. It is shown that although\nnot exact, this earlier suggestion nevertheless provides a very sensible way of\nnormalization of the self-diffusion constant. Additionally, we demonstrate that\ncertain quantitative properties of self-diffusion in Yukawa melts are also\nshared by systems like one-component plasma and liquid metals at freezing,\nproviding support to an emerging dynamical freezing indicator for simple soft\nmatter systems. The obtained results are also briefly discussed in the context\nof the theory of momentum transfer in complex (dusty) plasmas."
    },
    {
        "anchor": "The Anomalous Transport of Tracers in Active Baths: We derive the long-time dynamics of a tracer immersed in a one-dimensional\nactive bath. In contrast to previous studies, we find that the damping and\nnoise correlations possess long-time tails with exponents that depend on the\ntracer symmetry. For generic tracers, shape asymmetry induces ratchet effects\nthat alter fluctuations and lead to superdiffusion and friction that grows with\ntime when the tracer is dragged at a constant speed. In the singular limit of a\ncompletely symmetric tracer, we recover normal diffusion and finite friction.\nFurthermore, for small symmetric tracers, the active contribution to the\nfriction becomes negative: active particles enhance motion rather than oppose\nit. These results show that, in low-dimensional systems, the motion of a\npassive tracer in an active bath cannot be modeled as a persistent random\nwalker with a finite correlation time.",
        "positive": "Entropy Scaling Laws in Self Propelled Glass Formers: Predicting transport from equilibrium structure is a challenging problem in\nliquid state physics. Here we probe a glass forming liquid composed of\nself-propelled \"active\" particles and show that increasing the duration of\nself-propulsion $\\tau_p$ makes the pair excess entropy $S_2$ more negative,\nthereby reducing the number of accessible configurations per particle. At\nmoderate values of effective temperature $T$, the self-diffusivity is Arrhenius\nand in a reduced form obeys a Dzugutov like scaling law $D^* \\sim e^{\\alpha\nS_2}$, directly yielding us the scaling formula $S_2 \\sim -1/T$. In the\nstrongly super-cooled regime, Dzugutov law does not apply and the entropy\n  follows a power law $S_2 \\sim -1/T^{\\beta}$ all the way up to the glass\ntransition $T_g$. To demonstrate generality, we set the particle interactions\nto be purely repulsive (PR) in one case and Lennard-Jones (LJ) in the other,\nand find that in both the cases, the reported scaling laws are robust over\nthree decades of variation in $\\tau_p$. Our results may apply to transport in\nactive colloidal suspensions, passive tracers in bacterial baths, and\nself-propelled granular media, to mention a few."
    },
    {
        "anchor": "Long-range Velocity Correlations from Active Dopants: One of the most remarkable observations in dense active matter systems is the\nappearance of long-range velocity correlations without any explicit aligning\ninteraction (of e.g.\\ Vicsek type). Here we show that this kind of long range\nvelocity correlation can also be generated in a dense athermal passive system\nby the inclusion of a very small fraction of active Brownian particles. We\ndevelop a continuum theory to explain the emergence of velocity correlations\ngenerated via such active dopants. We validate the predictions for the effects\nof magnitude and persistence time of the active force and the area fractions of\nactive or passive particles using extensive Brownian dynamics simulation of a\ncanonical active-passive mixture. Our work decouples the roles that density and\nactivity play in generating long range velocity correlations in such exotic\nnon-equilibrium steady states.",
        "positive": "Two-dimensional flow of foam around an obstacle: force measurements: A Stokes experiment for foams is proposed. It consists in a two-dimensional\nflow of a foam, confined between a water subphase and a top plate, around a\nfixed circular obstacle. We present systematic measurements of the drag exerted\nby the flowing foam on the obstacle, \\emph{versus} various separately\ncontrolled parameters: flow rate, bubble volume, bulk viscosity, obstacle size,\nshape and boundary conditions. We separate the drag into two contributions, an\nelastic one (yield drag) at vanishing flow rate, and a fluid one (viscous\ncoefficient) increasing with flow rate. We quantify the influence of each\ncontrol parameter on the drag. The results exhibit in particular a power-law\ndependence of the drag as a function of the bulk viscosity and the flow rate\nwith two different exponents. Moreover, we show that the drag decreases with\nbubble size, and increases proportionally to the obstacle size. We quantify the\neffect of shape through a dimensioned drag coefficient, and we show that the\neffect of boundary conditions is small."
    },
    {
        "anchor": "Generic phases of cross-linked active gels: Relaxation, Oscillation and\n  Contractility: We study analytically and numerically a generic continuum model of an\nisotropic active solid with internal stresses generated by non-equilibrium\n`active' mechano-chemical reactions. Our analysis shows that the gel can be\ntuned through three classes of dynamical states by increasing motor activity: a\nconstant unstrained state of homogeneous density, a state where the local\ndensity exhibits sustained oscillations, and a steady-state which is\nspontaneously contracted, with a uniform mean density.",
        "positive": "Colloidal Jamming at Interfaces: a Route to Fluid-bicontinuous Gels: Colloidal particles or nanoparticles, with equal affinity for two fluids, are\nknown to adsorb irreversibly to the fluid-fluid interface. We present\nlarge-scale computer simulations of the demixing of a binary solvent containing\nsuch particles. The newly formed interface sequesters the colloidal particles;\nas the interface coarsens, the particles are forced into close contact by\ninterfacial tension. Coarsening is dramatically curtailed, and the jammed\ncolloidal layer seemingly enters a glassy state, creating a multiply connected,\nsolid-like film in three dimensions. The resulting gel contains percolating\ndomains of both fluids, with possible uses as, for example, a microreaction\nmedium."
    },
    {
        "anchor": "Strong-coupling theory of counterions between symmetrically charged\n  walls: from crystal to fluid phases: We study thermal equilibrium of classical pointlike counterions confined\nbetween symmetrically charged walls at distance $d$. At very large couplings\nwhen the counterion system is in its crystal phase, a harmonic expansion of\nparticle deviations is made around the bilayer positions, with a free lattice\nparameter determined from a variational approach. For each of the two walls,\nthe harmonic expansion implies an effective one-body potential at the root of\nall observables of interest in our Wigner Strong-Coupling expansion. Analytical\nresults for the particle density profile and the pressure are in good agreement\nwith numerical Monte Carlo data, for small as well as intermediate values of\n$d$ comparable with the Wigner lattice spacing. While the strong-coupling\ntheory is extended to the fluid regime by using the concept of a correlation\nhole, the Wigner calculations appear trustworthy for all electrostatic\ncouplings investigated. Our results significantly extend the range of accuracy\nof analytical equations of state for strongly interacting charged planar\ninterfaces.",
        "positive": "Permeability of immobile rings of membrane inclusions to in-plane flow: We study the flow of membranal fluid through a ring of immobile particles\nmimicking, for example, a fence around a membrane corral. We obtain a simple\nclosed-form expression for the permeability coefficient of the ring as a\nfunction of the particles' line fraction. The analytical results agree with\nthose of numerical calculations and are found to be robust against changes in\nparticle number and corral shape. From the permeability results we infer the\ncollective diffusion coefficient of lipids through the ring and discuss\npossible implications for collective lipid transport in a crowded membrane."
    },
    {
        "anchor": "Heterogeneous attenuation of sound waves in three-dimensional amorphous\n  solids: Sound waves are attenuated as they propagate in amorphous materials. We\ninvestigate the mechanism driving sound attenuation in the Rayleigh scattering\nregime by resolving the dynamics of an excited phonon in time and space via\nnumerical simulations. We find sound attenuation is spatiotemporal\nheterogeneous. It starts in localised regions, which identify soft regions\nwithin the material and correlate with low-frequency vibrational modes. As time\nprogresses, the regions where sound is primarily attenuated invade the system\nvia an apparent diffusive process.",
        "positive": "Stirring by swimmers in confined microenvironments: We consider the tracer diffusion $D_{rr}$ that arises from the run-and-tumble\nmotion of low Reynolds number swimmers, such as bacteria. In unbounded dilute\nsuspensions, where the dipole swimmers move in uncorrelated runs of length\n$\\lambda$, an exact solution showed that $D_{rr}$ is independent of $\\lambda$.\nHere we verify this result in numerical simulations for a particular model\nswimmer, the spherical squirmer. We also note that in confined\nmicroenvironments, such as microscopic droplets, microfluidic devices and\nbacterial microzones in marine ecosystems, the size of the system can be\ncomparable to $\\lambda$. We show that this effect alone reduces the value of\n$D_{rr}$ in comparison to its bulk value, and predict a scaling form for its\nrelative decrease."
    },
    {
        "anchor": "Continuous phase transition in polydisperse hard-sphere mixture: In a previous paper (J. Zhang {\\it et al.}, J. Chem. Phys. {\\bf 110}, 5318\n(1999)) we introduced a model for polydisperse hard sphere mixtures that is\nable to adjust its particle-size distribution. Here we give the explanation of\nthe questions that arose in the previous description and present a consistent\ntheory of the phase transition in this system, based on the Percus-Yevick\nequation of state. The transition is continuous, and like Bose-Einstein\ncondensation a macroscopic aggregate is formed due to the microscopic\ninteractions. A BMCSL-like treatment leads to the same conclusion with slightly\nmore accurate predictions.",
        "positive": "Atomistic modeling of heat treatment processes for tuning the mechanical\n  properties of disordered solids: We investigate the effect of a single heat treatment cycle on the potential\nenergy states and mechanical properties of metallic glasses using molecular\ndynamics simulations. We consider the three-dimensional binary mixture, which\nwas initially cooled with a computationally slow rate from the liquid state to\nthe solid phase at a temperature well below the glass transition. It was found\nthat a cycle of heating and cooling can relocate the glass to either\nrejuvenated or relaxed states, depending on the maximum temperature and the\nloading period. Thus, the lowest potential energy is attained after a cycle\nwith the maximum temperature slightly below the glass transition temperature\nand the effective cooling rate slower than the initial annealing rate. In\ncontrast, the degree of rejuvenation increases when the maximum temperature\nbecomes greater than the glass transition temperature and the loading period is\nsufficiently small. It was further shown that the variation of the potential\nenergy is inversely related to the dependence of the elastic modulus and the\nyield stress as functions of the maximum loading temperature. In addition, the\nheat treatment process causes subtle changes in the shape of the radial\ndistribution function of small atoms. These results are important for\noptimization of thermal and mechanical processing of metallic glasses with\npredetermined properties."
    },
    {
        "anchor": "Steady base states for Navier-Stokes granular hydrodynamics with\n  boundary heating and shear: We study the Navier-Stokes steady states for a low density monodisperse hard\nsphere granular gas (i.e, a hard sphere ideal monatomic gas with inelastic\ninterparticle collisions). We present a classification of the uniform steady\nstates that can arise from shear and temperature (or energy input) applied at\nthe boundaries (parallel walls). We consider both symmetric and asymmetric\nboundary conditions and find steady states not previously reported, including\nsheared states with linear temperature profiles. We provide explicit\nexpressions for the hydrodynamic profiles for all these steady states. Our\nresults are validated by the numerical solution of the Boltzmann kinetic\nequation for the granular gas obtained by the direct simulation Monte Carlo\nmethod, and by molecular dynamics simulations. We discuss the physical origin\nof the new steady states and derive conditions for the validity of\nNavier-Stokes hydrodynamics.",
        "positive": "Structural properties of cyclic polyelectrolytes in dilute good solvent: Cyclic polymers display unique physical behaviors in comparison to their\nlinear counterparts. Theoretical, computational and experimental studies have\nrevealed that some of their distinctive properties are also observed in charged\nvariants of cyclic polymers, known as cyclic polyelectrolytes (PEs), especially\nin terms of their structural responses to variations in the strength of\nelectrostatic interactions. In this study, we investigate the impact of cyclic\ntopology on the conformations of PE chains in dilute good solvent using scaling\nanalysis and coarse-grained bead-spring molecular dynamics simulations. Our\nobservations indicate that, in contrast to linear PE chains, cyclic topology\nresults in more compact conformations at low and intermediate Bjerrum lengths.\nMoreover, two structural metrics, asphericity and prolateness, which quantify\ndeviations from spherical and flat molecular shapes, exhibit non-monotonic\nbehaviors for cyclic PEs. This stands in contrast to linear PEs, where these\nshape characteristics exhibit a monotonic trend with increasing Bjerrum length.\nA feasible analytical theory, developed to account for ionic distributions\naround cyclic PE chains, suggests that the fundamental difference between\nlinear and cyclic chain conformations may be attributed to topological effects\ninfluencing long-range electrostatic interactions."
    },
    {
        "anchor": "Stress and Alignment Response to Curved Obstacles in Growing Bacterial\n  Monolayers: Monolayers of growing bacteria, confined within channel geometries, exhibit\nself-organization into a highly aligned laminar state along the axis of the\nchannel. Although this phenomenon has been observed in experiments and\nsimulations under various boundary conditions, the underlying physical\nmechanism driving this alignment remains unclear. In this study, we conduct\nsimulations of growing bacteria in 2D channel geometries perturbed by fixed\nobstacles, either circular or arc-shaped, placed at the channel's center. Our\nfindings reveal that even sizable obstacles cause only short-ranged disruptions\nto the baseline laminar state. These disruptions arise from a competition\nbetween local planar anchoring and bulk laminar alignment. At smaller obstacle\nsizes, bulk alignment fully dominates, while at larger sizes, planar anchoring\ninduces increasing local disruptions. Furthermore, our analysis indicates that\nthe resulting configurations of the bacterial system display a striking\nresemblance to the arrangement of hard-rod smectic liquid crystals around\ncircular obstacles. This suggests that modeling hard-rod bacterial monolayers\nas smectic, rather than nematic, liquid crystals may yield successful outcomes.\nThe insights gained from our study contribute to the expanding body of research\non bacterial growth in channels. Our work provides new perspectives on the\nstability of the laminar state and extends our understanding to encompass more\nintricate confinement schemes.",
        "positive": "From Dry to Wet Vertex Model Dynamics: Generating Sustained Flows: Complex tissue flows in epithelia are driven by intra- and inter-cellular\nprocesses that generate, maintain, and coordinate mechanical forces. There has\nbeen growing evidence that cell shape anisotropy, manifested as nematic order,\nplays an important role in this process. Here we extend a nematic vertex model\nby replacing substrate friction with internal viscous dissipation, of relevance\nto epithelia not supported by a substrate or the extracellular matrix, such as\nmany early-stage embryos. When coupled to cell shape anisotropy, the internal\nviscous dissipation allows for long-range velocity correlations and thus\nenables the spontaneous emergence of flows with a large degree of\nspatiotemporal organisation. We demonstrate sustained flow in epithelial sheets\nconfined to a channel, thus providing a link between the dynamical behaviour of\ncontinuum active nematics and the cell-level vertex model of tissue dynamics."
    },
    {
        "anchor": "Cavity nucleation in single-component homogeneous amorphous solids under\n  negative pressure: Understanding the cavity formation and cavity growth mechanisms in solids has\nfundamental and applied importance for the correct determination of their\nexploitation capabilities and mechanical characteristics. In this work, we\npresent the molecular dynamics simulation results for the process of\nhomogeneous formation of nanosized cavities in a single-component amorphous\nmetallic alloy. To identify cavities of various shapes and sizes, an original\nmethod has been developed, which is based on filling cavities by virtual\nparticles (balls) of the same diameter. By means of the mean first-passage time\nanalysis, it was shown that the cavity formation in an amorphous metallic melt\nis the activation-type process. This process can be described in terms of the\nclassical nucleation theory, which is usually applied to the case of first\norder phase transitions. Activation energy, critical size and nucleation rate\nof cavities are calculated, the values of which are comparable with those for\nthe case of crystal nucleation in amorphous systems.",
        "positive": "Solid-supported lipid multilayers: Structure factor and fluctuations: We present a theoretical description of the thermal fluctuations in a\nsolid-supported stack of lipid bilayers, for the case of vanishing surface\ntension $\\gamma = 0$ and in the framework of continuous smectic elasticity. The\nmodel is successfully used to model the reflectivity profile of a thin (16\nbilayers) DMPC sample under applied osmotic pressure and the diffuse scattering\nfrom a thick (800 bilayers) stack. We compare our model to previously existing\ntheories."
    },
    {
        "anchor": "Velocity Correlations in Dense Gravity Driven Granular Chute Flow: We report numerical results for velocity correlations in dense,\ngravity-driven granular flow down an inclined plane. For the grains on the\nsurface layer, our results are consistent with experimental measurements\nreported by Pouliquen. We show that the correlation structure within planes\nparallel to the surface persists in the bulk. The two-point velocity\ncorrelation function exhibits exponential decay for small to intermediate\nvalues of the separation between spheres. The correlation lengths identified by\nexponential fits to the data show nontrivial dependence on the averaging time\n$\\dt$ used to determine grain velocities. We discuss the correlation length\ndependence on averaging time, incline angle, pile height, depth of the layer,\nsystem size and grain stiffness, and relate the results to other length scales\nassociated with the rheology of the system. We find that correlation lengths\nare typically quite small, of the order of a particle diameter, and increase\napproximately logarithmically with a minimum pile height for which flow is\npossible, $\\hstop$, contrary to the theoretical expectation of a proportional\nrelationship between the two length scales.",
        "positive": "Spontaneous division and motility in active nematic droplets: We investigate the mechanics of an active droplet endowed with internal\nnematic order and surrounded by an isotropic Newtonian fluid. Using numerical\nsimulations we demonstrate that, due to the interplay between the active\nstresses and the defective geometry of the nematic director, this system\nexhibits two of the fundamental functions of living cells: spontaneous division\nand motility, by means of self-generated hydrodynamics flows. These behaviors\ncan be selectively activated by controlling a single physical parameter,\nnamely, an active variant of the capillary number."
    },
    {
        "anchor": "Electrostatic and electrokinetic contributions to the elastic moduli of\n  a driven membrane: We discuss the electrostatic contribution to the elastic moduli of a cell or\nartificial membrane placed in an electrolyte and driven by a DC electric field.\nThe field drives ion currents across the membrane, through specific channels,\npumps or natural pores. In steady state, charges accumulate in the Debye layers\nclose to the membrane, modifying the membrane elastic moduli. We first study a\nmodel of a membrane of zero thickness, later generalizing this treatment to\nallow for a finite thickness and finite dielectric constant. Our results\nclarify and extend the results presented in [D. Lacoste, M. Cosentino\nLagomarsino, and J. F. Joanny, Europhys. Lett., {\\bf 77}, 18006 (2007)], by\nproviding a physical explanation for a destabilizing term proportional to\n$\\kps^3$ in the fluctuation spectrum, which we relate to a nonlinear ($E^2$)\nelectro-kinetic effect called induced-charge electro-osmosis (ICEO). Recent\nstudies of ICEO have focused on electrodes and polarizable particles, where an\napplied bulk field is perturbed by capacitive charging of the double layer and\ndrives flow along the field axis toward surface protrusions; in contrast, we\npredict \"reverse\" ICEO flows around driven membranes, due to curvature-induced\ntangential fields within a non-equilibrium double layer, which hydrodynamically\nenhance protrusions. We also consider the effect of incorporating the dynamics\nof a spatially dependent concentration field for the ion channels.",
        "positive": "Identifying time scales for violation/preservation of Stokes-Einstein\n  relation in supercooled water: The violation of Stokes--Einstein (SE) relation $D\\sim (\\eta/T)^{-1}$ between\nthe shear viscosity $\\eta$ and the translational diffusion constant $D$ at\ntemperature $T$ is of great importance for characterizing anomalous dynamics of\nsupercooled water. Determining which time scales play key roles in the SE\nviolation remains elusive without the measurement of $\\eta$. Here we provide\ncomprehensive simulation results of the dynamic properties involving $\\eta$ and\n$D$ in TIP4P/2005 supercooled water. This enabled the thorough identification\nof the appropriate time scales for SE relation $D\\eta/T$. In particular, it is\ndemonstrated that the temperature dependence of various time scales associated\nwith structural relaxation, hydrogen bond breakage, stress relaxation, and\ndynamic heterogeneities can be definitely classified into only two classes.\nThat is, we propose the generalized SE relations that exhibit \"violation\" or\n\"preservation\". The classification depends on the examined time scales that are\ncoupled or decoupled with the diffusion. On the basis of the classification, we\nexplain the physical origins of the violation in terms of the increase in the\nplateau modulus and the nonexponentiality of stress relaxation. This implies\nthat the mechanism of SE violation is attributed to the attained solidity upon\nsupercooling, which is in accord with the growth of non-Gaussianity and\nspatially heterogeneous dynamics."
    },
    {
        "anchor": "An Eulerian approach to the simulation of deformable solids: Application\n  to finite-strain elasticity: We develop a computational method based on an Eulerian field called the\n\"reference map\", which relates the current location of a material point to its\ninitial. The reference map can be discretized to permit finite-difference\nsimulation of large solid-like deformations, in any dimension, of the type that\nmight otherwise require the finite element method. The generality of the method\nstems from its ability to easily compute kinematic quantities essential to\nsolid mechanics, that are elusive outside of Lagrangian frame. This\nintroductory work focuses on large-strain, hyperelastic materials. After a\nbrief review of hyperelasticity, a discretization of the method is presented\nand some non-trivial elastic deformations are simulated, both static and\ndynamic. The method's accuracy is directly verified against known analytical\nsolutions.",
        "positive": "A Design Path for Hierarchical Self-Assembly of Patchy Colloids: Patchy colloids are promising candidates for building blocks in directed\nself-assembly. To be successful the surface patterns need to both be simple\nenough to be synthesized, while feature-rich enough to cause the colloids to\nself-assemble into desired structures. Achieving this is a challenge for\ntraditional synthesis methods. Recently it has been suggested that the surface\npattern themselves can be made to self-assemble. In this paper we show that a\nwide range of functional structures can be made to self-assemble using this\napproach. More generally we present a design path for hierarchical targeted\nself-assembly of patchy colloids. At the level of the surface structure, we use\na predictive method utilizing universality of patterns of stripes and spots,\ncoupled with stoichiometric constraints, to cause highly specific and\nfunctional patterns to self-assemble on spherical surfaces. We use a\nminimalistic model of an alkanethiol on gold as a model system and demonstrate\nthat, even with limited control over the interaction between surface\nconstituents, we can obtain patterns that causes the colloids themselves to\nself-assemble into various complex geometric structures. We demonstrate how\nvariations of the same design path cause in-silico self-assembly of strings,\nmembranes, cubic and spherical aggregates, as well as various crystalline\npatterns."
    },
    {
        "anchor": "With a little help of DNA: Morphological diversity of colloidal\n  self-assembly: We study theoretically a binary system in which an attraction of unlike\nparticles is combined with a type-independent soft core repulsion.\n  The possible experimental implementation of the system is a mixture of\nDNA-covered colloids, in which both the repulsion and the attraction may be\ninduced by DNA solution. The system is shown to exhibit surprisingly diverse\nand unusual morphologies. Among them are the diamond lattice and the membrane\nphase with in-plane square order, a striking example of spontaneous\ncompactification.",
        "positive": "Critical behavior of charge-regulated macro-ions: Based on a collective description of electrolytes composed of\ncharge-regulated macro-ions and simple salt ions, we analyze their equilibrium\ncharge state in the bulk and their behavior in the vicinity of an external\nelectrified surface. The mean-field formulation of mobile macro-ions in an\nelectrolyte bathing solution is extended to include interactions between\nassociation/dissociation sites. We demonstrate that above a critical\nconcentration of salt, and similar to the critical micelle concentration, a\nnon-trivial distribution of charge states sets in. Such a charge state can\neventually lead to a liquid-liquid phase separation based on charge regulation."
    },
    {
        "anchor": "Equation of State and Entropy Theory Approach to Thermodynamic Scaling\n  in Polymeric Glass-Forming Liquids: We show that thermodynamic scaling can be derived by combining the Murnaghan\nequation of state (EOS) with the generalized entropy theory (GET) of glass\nformation. In our theory, thermodynamic scaling arises in the non-Arrhenius\nrelaxation regime as a scaling property of the fluid configurational entropy\ndensity $s_c$, normalized by its value $s_c^*$ at the onset temperature $T_A$\nof glass formation, $s_c / s_c^*$, so that a constant value of $TV^{\\gamma}$\ncorresponds to a \\textit{reduced isoentropic} fluid condition. Molecular\ndynamics simulations on a coarse-grained polymer melt are utilized to confirm\nthat the predicted thermodynamic scaling of $\\tau_{\\alpha}$ by the GET holds\nboth above and below $T_A$ and to test whether the extent $L$ of stringlike\ncollective motion, normalized its value $L_A$ at $T_A$, also obeys\nthermodynamic scaling, as required for consistency with thermodynamic scaling.\nWhile the predicted thermodynamic scaling of both $\\tau_{\\alpha}$ and $L/ L_A$\nis confirmed by simulation, we find that the isothermal compressibility\n$\\kappa_T$ and the long wavelength limit $S(0)$ of the static structure factor\ndo not exhibit thermodynamic scaling, an observation that would appear to\neliminate some proposed models of glass formation emphasizing fluid `structure'\nover configurational entropy. It is found, however, that by defining a low\ntemperature hyperuniform reference state, we may define a compressibility\nrelative to this condition, $\\delta \\kappa_T$, a transformed dimensionless\nvariable that exhibits thermodynamic scaling and which can be directly related\nto $s_c / s_c^*$. Further, the Murnaghan EOS allows us to interpret $\\gamma$ as\na measure of intrinsic anharmonicity of intermolecular interactions that may be\ndirectly determined from the pressure derivative of the material bulk modulus.",
        "positive": "Joint density-functional theory for electronic structure of solvated\n  systems: We introduce a new form of density functional theory for the {\\em ab initio}\ndescription of electronic systems in contact with a molecular liquid\nenvironment. This theory rigorously joins an electron density-functional for\nthe electrons of a solute with a classical density-functional theory for the\nliquid into a single variational principle for the free energy of the combined\nsystem. A simple approximate functional predicts, without any fitting of\nparameters to solvation data, solvation energies as well as state-of-the-art\nquantum-chemical cavity approaches, which require such fitting."
    },
    {
        "anchor": "Scaling features of the tribology of polymer brushes of increasing\n  grafting density around the mushroom to brush transition: Non equilibrium coarse grained, dissipative particle dynamics simulations of\ncomplex fluids, made up of polymer brushes tethered to planar surfaces immersed\nin a solvent yield non monotonic behavior of the friction coefficient as a\nfunction of the polymer grating density on the substrates, \\Gamma, while the\nviscosity shows a monotonically increasing dependence on \\Gamma. This effect is\nshown to be independent of the degree of polymerization, N, and the size of the\nsystem. It arises from the composition and the structure of the first particle\nlayer adjacent to each surface that results from the confinement of the fluid.\nWhenever such layers are made up of as close a proportion of polymer beads to\nsolvent particles as there are in the fluid, the friction coefficient shows a\nminimum, while for disparate proportions the friction coefficient grows. At the\nmushroom to brush transition (MBT) the viscosity scales with an exponent that\ndepends on the characteristic exponent of the MBT (6/5) and the solvent quality\nexponent (\\nu = 0.5, for theta solvent), but it is independent of the\npolymerization degree (N). On the other hand, the friction coefficient at the\nMBT scales as {\\mu}~N^(6/5), while the grafting density at the MBT scales as\n{\\Gamma}~ N^(-6/5) when friction is minimal, in agreement with previous scaling\ntheories. We argue these aspects are the result of cooperative phenomena that\nhave important implications for the understanding of biological brushes and the\ndesign of microfluidics devices, among other applications of current academic\nand industrial interest.",
        "positive": "Propulsion of bullet- and cup-shaped nano- and microparticles by\n  traveling ultrasound waves: The propulsion of colloidal particles via planar traveling ultrasound waves\nhas attracted increasing attention in recent years. A frequently studied type\nof particles is bullet-shaped and cup-shaped nano- and microparticles. Based on\nacoustofluidic simulations, this article investigates how the propulsion of\nbullet-shaped particles depends on their length and diameter, where cup-shaped\nparticles are included as limiting cases corresponding to the smallest particle\nlength. The structure of the flow field generated by the particles is discussed\nand it is shown that the particles' propulsion strength increases with their\nlength and diameter. When varying the diameter, we observed also a sign change\nof the propulsion. This work complements previous experimental studies that\nhave addressed such particles only for particular aspect ratios, and the\nprovided understanding of how the propulsion of the particles depends on their\ndimensions will prospectively be helpful for the choice of particle shapes that\nare most suitable for future experimental studies."
    },
    {
        "anchor": "Photoalignment at the nematic liquid crystal - polymer interface: the\n  importance of the liquid crystalline molecular structure: The influence of the molecular structure of the nematic liquid crystal (NLC)\non the photoalignment process at the NLC -- polymer interface has been\ninvestigated experimentally. NLCs having exclusively phenyl-, or cyclohexane\nrings in the rigid core, as well as NLCs containing both phenyl and cyclohexane\ngroups have been considered. Substantial differences have been found in the\nphotoalignment process depending on the molecular structure of the NLC,\nsupporting the assumption that the polymer -- NLC interface should be regarded\nas a coupled system, where the two components mutually influence each other. A\nphenomenological explanation is given for the observed differences.",
        "positive": "Monolayers of hard rods on planar substrates: II. Growth: Growth of hard--rod monolayers via deposition is studied in a lattice model\nusing rods with discrete orientations and in a continuum model with hard\nspherocylinders. The lattice model is treated with kinetic Monte Carlo\nsimulations and dynamic density functional theory while the continuum model is\nstudied by dynamic Monte Carlo simulations equivalent to diffusive dynamics.\nThe evolution of nematic order (excess of upright particles, \"standing--up\"\ntransition) is an entropic effect and is mainly governed by the equilibrium\nsolution, {rendering a continuous transition} (paper I, J. Chem. Phys. 145,\n074902 (2016)). Strong non--equilibrium effects (e.g. a noticeable dependence\non the ratio of rates for translational and rotational moves) are found for\nattractive substrate potentials favoring lying rods. Results from the lattice\nand the continuum models agree qualitatively if the relevant characteristic\ntimes for diffusion, relaxation of nematic order and deposition are matched\nproperly. Applicability of these monolayer results to multilayer growth is\ndiscussed for a continuum--model realization in three dimensions where\nspherocylinders are deposited continuously onto a substrate via diffusion."
    },
    {
        "anchor": "Dynamic instability of a growing adsorbed polymorphic filament: The intermittent transition between slow growth and rapid shrinkage in\npolymeric assemblies is termed dynamic instability, a feature observed in a\nvariety of biochemically distinct assemblies including microtubules, actin and\ntheir bacterial analogs. The existence of this labile phase of a polymer has\nmany functional consequences in cytoskeletal dynamics, and its repeated\nappearance suggests that it is relatively easy to evolve. Here, we consider the\nminimal ingredients for the existence of dynamic instability by considering a\nsingle polymorphic filament that grows by binding to a substrate, undergoes a\nconformation change, and may unbind as a consequence of the residual strains\ninduced by this change. We identify two parameters that control the phase space\nof possibilities for the filament: a structural mechanical parameter that\ncharacterizes the ratio of the bond strengths along the filament to those with\nthe substrate (or equivalently the ratio of longitudinal to lateral\ninteractions in an assembly), and a kinetic parameter that characterizes the\nratio of time scales for growth and conformation change. In the deterministic\nlimit, these parameters serve to demarcate a region of uninterrupted growth\nfrom that of collapse. However, in the presence of disorder in either the\nstructural or the kinetic parameter the growth and collapse phases can coexist\nwhere the filament can grow slowly, shrink rapidly, and transition between\nthese phases, thus exhibiting dynamic instability. We exhibit the window for\nthe existence of dynamic instability in a phase diagram that allows us to\nquantify the evolvability of this labile phase.",
        "positive": "Critical aspects of hierarchical protein folding: We argue that the first order folding transitions of proteins observed at\nphysiological chemical conditions end in a critical point for a given\ntemperature and chemical potential of the surrounding water. We investigate\nthis critical point using a hierarchical Hamiltonian and determine its\nuniversality class. This class differs qualitatively from those of other known\nmodels."
    },
    {
        "anchor": "Effects of Pore Connectivity and Tortuosity on the Dynamics of Fluids\n  Confined in Sub-nanometer Pores: We report molecular dynamics simulation studies addressing the effects of\npore connectivity on the dynamics of two representative fluids CO$_2$ and\nethane in silicalite by systematically varying the degree of pore connectivity\nthrough selectively blocking some pore space with immobile methane molecules.\nBy selectively turning off the pore spaces in the shape of straight, or\ntortuous zigzag channels, we also probe the effects of pore tortuosity. In\ngeneral, pore connectivity is found to facilitate both the translational as\nwell as rotational dynamics of both fluids, while the intermolecular modes of\nvibration in both fluids remain largely unaffected. The effects of providing\nconnections between a set of straight or zigzag channel-like pores are however\nmore nuanced. Pore tortuosity facilitates the rotational motion, but suppresses\nthe translational motion of CO$_2$, while its effects on the rotational and\ntranslational motion of ethane are less pronounced. The intermolecular\nvibrational modes of both fluids shift to higher energies with an increase in\nthe number of tortuous pores. The results reported here provide a detailed\nmolecular level understanding of the effects of pore connectivity on the\ndynamics of fluids and thus have implications for applications like fluid\nseparation.",
        "positive": "Finding a unifying motif of intermolecular cooperativity in protein\n  associations: At the molecular level, most biological processes entail protein associations\nwhich in turn rely on a small fraction of interfacial residues called hot\nspots. Here we show that hot spots share a unifying molecular attribute: they\nprovide a third-body contribution to intermolecular cooperativity. Such motif,\nbased on the wrapping of interfacial electrostatic interactions, is essential\nto maintain the integrity of the interface and can be exploited in rational\ndrug design since such regions may serve as blueprints to engineer small\nmolecules disruptive of protein-protein interfaces."
    },
    {
        "anchor": "Solvation Effects in Near-Critical Binary Mixtures: A Ginzburg-Landau theory is presented to investigate solvation effects in\nnear-critical polar fluid binary mixtures. Concentration-dependence of the\ndielectric constant gives rise to a shell region around a charged particle\nwithin which solvation occurs preferentially. As the critical point is\napproached, the concentration has a long-range Ornstein-Zernike tail\nrepresenting strong critical electrostriction. If salt is added, strong\ncoupling arises among the critical fluctuations and the ions. The structure\nfactors of the critical fluctuations and the charge density are calculated and\nthe phase transition behavior is discussed.",
        "positive": "Shear and normal stress measurements in non-Brownian monodisperse and\n  bidisperse suspensions: There was an error in data reduction, resulting in incorrect values for the\nnormal stress differences $N_1$ and $N_2$ shown in Figs. 7-10, and the\ncorrected figures are shown here. In particular, the algebraic sign of $N_1$ is\nchanged, as are the relative magnitudes of $N_1$ and $N_2$. The negative values\nof $N_1$ for these non-shear-thickening suspensions are larger in magnitude\nthan those reported by other workers, but both $N_1$ and $N_2$ are in general\nagreement with the accelerated Stokesian Dynamics calculations of Sierou and\nBrady [1]."
    },
    {
        "anchor": "Anomalous fluctuations in a droplet of chemically active colloids or\n  enzymes: Chemically active colloids or enzymes cluster into dense droplets driven by\ntheir phoretic response to collectively generated chemical gradients. Employing\nBrownian dynamics simulation techniques, our study of the dynamics of such a\nchemically active droplet uncovers a rich variety of structures and dynamical\nproperties, including the full range of fluid-like to solid-like behaviour, and\nnon-Gaussian positional fluctuations. Our work sheds light on the complex\ndynamics of the active constituents of metabolic clusters, which are the main\ndrivers of non-equilibrium activity in living systems.",
        "positive": "Folding Langmuir Monolayers: The maximum pressure a two-dimensional surfactant monolayer is able to\nwithstand is limited by the collapse instability towards formation of\nthree-dimensional material. We propose a new description for reversible\ncollapse based on a mathematical analogy between the formation of folds in\nsurfactant monolayers and the formation of Griffith Cracks in solid plates\nunder stress. The description, which is tested in a combined microscopy and\nrheology study of the collapse of a single-phase Langmuir monolayer of\n2-hydroxy-tetracosanoic acid (2-OH TCA), provides a connection between the\nin-plane rheology of LM's and reversible folding."
    },
    {
        "anchor": "Core-Softened System With Attraction: Trajectory Dependence of Anomalous\n  Behavior: In the present article we carry out a molecular dynamics study of the\ncore-softened system and show that the existence of the water-like anomalies in\nthis system depends on the trajectory in $P-\\rho-T$ space along which the\nbehavior of the system is studied. For example, diffusion and structural\nanomalies are visible along isotherms as a function of density, but disappears\nalong the isochores and isobars as a function of temperature. On the other\nhand, the diffusion anomaly may be seen along adiabats as a function of\ntemperature, density and pressure. It should be noted that it may be no\nsignature of a particular anomaly along a particular trajectory, but the\nanomalous region for that particular anomaly can be defined when all possible\ntrajectories in the same space are examined (for example, signature of\ndiffusion anomaly is evident through the crossing of different isochors.\nHowever, there is no signature of diffusion anomaly along a particular\nisochor). We also analyze the applicability of the Rosenfeld entropy scaling\nrelations to this system in the regions with the water-like anomalies. It is\nshown that the validity of the Rosenfeld scaling relation for the diffusion\ncoefficient also depends on the trajectory in the $P-\\rho-T$ space along which\nthe kinetic coefficients and the excess entropy are calculated.",
        "positive": "The chiral magnetic nanomotors: Propulsion of the chiral magnetic nanomotors powered by a rotating magnetic\nfield is in the focus of the modern biomedical applications. This technology\nrelies on strong interaction of dynamic and magnetic degrees of freedom of the\nsystem. Here we study in detail various experimentally observed regimes of the\nhelical nanomotor orientation and propulsion depending on the actuation\nfrequency, and establish the relation of these two properties with remanent\nmagnetization and geometry of the helical nanomotors. The theoretical\npredictions for the transition between the regimes and nanomotor orientation\nand propulsion speed are in excellent agreement with available experimental\ndata. The proposed theory offers a few simple guidelines towards the optimal\ndesign of the magnetic nanomotors. In particular, efficient nanomotors should\nbe fabricated of hard magnetics, e.g., cobalt, magnetized transversally and\nhave the geometry of a normal helix with a helical angle of 35-45 degrees."
    },
    {
        "anchor": "Deriving hydrodynamic equations from dry active matter models in three\n  dimensions: We derive hydrodynamic equations from Vicsek-style dry active matter models\nin three dimensions (3D), building on our experience on the 2D case using the\nBoltzmann-Ginzburg-Landau approach. The hydrodynamic equations are obtained\nfrom a Boltzmann equation expressed in terms of an expansion in spherical\nharmonics. All their transport coefficients are given with explicit dependences\non particle-level parameters. The linear stability analysis of their\nspatially-homogeneous solutions is presented. While the equations derived for\nthe polar case (original Vicsek model with ferromagnetic alignment) and their\nsolutions do not differ much from their 2D counterparts, the active nematics\ncase exhibits remarkable differences: we find a true discontinuous transition\nto order with a bistability region, and cholesteric solutions whose stability\nwe discuss.",
        "positive": "Capacitance of the Double Layer Formed at the Metal/Ionic-Conductor\n  Interface: How Large Can It Be?: The capacitance of the double layer formed at a metal/ionic-conductor\ninterface can be remarkably large, so that the apparent width of the double\nlayer is as small as 0.3 \\AA. Mean-field theories fail to explain such large\ncapacitance. We propose an alternate theory of the ionic double layer which\nallows for the binding of discrete ions to their image charges in the metal. We\nshow that at small voltages the capacitance of the double layer is limited only\nby the weak dipole-dipole repulsion between bound ions, and is therefore very\nlarge. At large voltages the depletion of bound ions from one of the capacitor\nelectrodes triggers a collapse of the capacitance to the mean-field value."
    },
    {
        "anchor": "Enhancement of Optical Nonlinearity Through Anisotropic Microstructures: We investigate the polarization dependence of optical nonlinearity\nenhancement for a uniaxial anisotropic composite of metal nanocrystals in a\ndielectric host. Three cases are distinguished depending on whether the\npolarization is parallel, perpendicular or unpolarized with respect to the axis\nof anisotropy. For the parallel polarization, the results show that the 3D\nresults are qualitatively similar to the 2D case reported recently. For the\nperpendicular polarization, the results are markedly different from the\nparallel counterpart: In contrast to the absorption, the enhancement factor\nactually increases with the anisotropy. Thus the separation of the absorption\nand enhancement peaks becomes even more pronounced than the parallel\npolarization case. These results indicate a strong polarization dependence of\nthe nonlinear optical response.",
        "positive": "Theoretical analysis of screened many-body electrostatic interactions\n  between charged polarizable particles: This paper builds on two previous works, Lindgren et al. J. Comp. Phys. 371,\n712-731 (2018) and Quan et al. arXiv:1807.05384 (2018), to devise a new method\nto solve the problem of calculating electrostatic interactions in a system\ncomposed by many dielectric particles, embedded in a homogeneous dielectric\nmedium, which in turn can also be permeated by charge carriers. The system is\ndefined by the charge, size, position and dielectric constant of each particle,\nas well as the dielectric constant and Debye length of the medium. The effects\nof taking into account the dielectric nature of the particles is explored in\nselected scenarios where the presence of electrolytes in the medium can\nsignificantly influence the total undergoing interactions. Description of the\nmutual interactions between all particles in the system as being truly of\nmany-body nature reveals how such effects can effectively influence the\nmagnitudes and even directions of the resulting forces, especially those acting\non particles that have a null net charge. Particular attention is given to a\nsituation that can be related to colloidal particles in an electrolyte\nsolution, where it's shown that polarization effects alone can substantially\nraise or lower---depending on the dielectric contrast between the particles and\nthe medium---the energy barrier that divides particle coagulation and\nflocculation regions, when an interplay between electrostatic and additional\nvan der Waals forces is considered. Overall, the results suggest that for an\naccurate description of the type of system in question, it is essential to\nconsider particle polarization if the separation between the interacting\nparticles are comparable to or smaller than the Debye length of the medium."
    },
    {
        "anchor": "A Fourier-accelerated volume integral method for elastoplastic contact: The contact of solids with rough surfaces plays a fundamental role in\nphysical phenomena such as friction, wear, sealing, and thermal transfer.\nHowever, its simulation is a challenging problem due to surface asperities\ncovering a wide range of length-scales. In addition, non-linear local\nprocesses, such as plasticity, are expected to occur even at the lightest\nloads. In this context, robust and efficient computational approaches are\nrequired. We therefore present a novel numerical method, based on integral\nequations, capable of handling the large discretization requirements of real\nrough surfaces as well as the non-linear plastic flow occurring below and at\nthe contacting asperities. This method is based on a new derivation of the\nMindlin fundamental solution in Fourier space, which leverages the\ncomputational efficiency of the fast Fourier transform. The use of this Mindlin\nsolution allows a dramatic reduction of the memory imprint (as the Fourier\ncoefficients are computed on-the-fly), a reduction of the discretization error,\nand the exploitation of the structure of the functions to speed up computation\nof the integral operators. We validate our method against an elastic-plastic\nFEM Hertz normal contact simulation and showcase its ability to simulate\ncontact of rough surfaces with plastic flow.",
        "positive": "Consistent and transferrable coarse-grained model for semidilute polymer\n  solutions in good solvent: We present a coarse-grained model for linear polymers with a tunable number\nof effective atoms (blobs) per chain interacting by intra- and inter-molecular\npotentials obtained at zero density. We show how this model is able to\naccurately reproduce the universal properties of the underlying solution of\nathermal linear chains at various levels of coarse-graining and in a range of\nchain densities which can be widened by increasing the spatial resolution of\nthe multiblob representation, i.e., the number of blobs per chain. The present\nmodel is unique in its ability to quantitatively predict thermodynamic and\nlarge scale structural properties of polymer solutions deep in the semidilute\nregime with a very limited computational effort, overcoming most of the\nproblems related to the simulations of semidilute polymer solutions in good\nsolvent conditions."
    },
    {
        "anchor": "Rheology finds distinct glass and jamming transitions in emulsions: We study the rheology of monodisperse and bidisperse emulsions with various\ndroplet sizes (1 $\\mu$m -- 2 $\\mu$m diameter). Above a critical volume fraction\n$\\phi_c$, these systems exhibit solid-like behavior and a yield stress can be\ndetected. Previous experiments suggest that for small thermal particles,\nrheology will see a glass transition at $\\phi_c = \\phi_g =0.58$; for large\nathermal systems, rheology will see a jamming transition at $\\phi_c = \\phi_J\n=0.64$. However, simulations point out that at the crossover of thermal and\nathermal regimes, the glass and jamming transitions may both be observed in the\nsame sample. Here we conduct an experiment by shearing four oil-in-water\nemulsions with a rheometer. We observe both a glass and a jamming transition\nfor our smaller diameter droplets, and only a jamming transition for our larger\ndiameter droplets. The bidisperse sample behaves similarly to the small droplet\nsample, with two transitions observed. Our rheology data are well-fit by both\nthe Herschel-Bulkley model and the Three Component model. Based on the fitting\nparameters, our raw rheological data would not collapse onto a master curve.\nOur results suggest that liquid-solid transitions in dispersions may not be\nuniversal, but depend on particle type.",
        "positive": "Surface Effects in Magnetic Microtraps: We have investigated Bose-Einstein condensates and ultra cold atoms in the\nvicinity of a surface of a magnetic microtrap. The atoms are prepared along\ncopper conductors at distances to the surface between 300 um and 20 um. In this\nrange, the lifetime decreases from 20 s to 0.7 s showing a linear dependence on\nthe distance to the surface. The atoms manifest a weak thermal coupling to the\nsurface, with measured heating rates remaining below 500 nK/s. In addition, we\nobserve a periodic fragmentation of the condensate and thermal clouds when the\nsurface is approached."
    },
    {
        "anchor": "Phase Diagram of Hard Tetrahedra: Advancements in the synthesis of faceted nanoparticles and colloids have\nspurred interest in the phase behavior of polyhedral shapes. Regular tetrahedra\nhave attracted particular attention because they prefer local symmetries that\nare incompatible with periodicity. Two dense phases of regular tetrahedra have\nbeen reported recently. The densest known tetrahedron packing is achieved in a\ncrystal of triangular bipyramids (dimers) with packing density\n4000/4671=85.63%. In simulation a dodecagonal quasicrystal is observed; its\napproximant, with periodic tiling (3.4.3^2.4), can be compressed to a packing\nfraction of 85.03%. Here, we show that the quasicrystal approximant is more\nstable than the dimer crystal for packing densities below 84% using Monte Carlo\ncomputer simulations and free energy calculations. To carry out the free energy\ncalculations, we use a variation of the Frenkel-Ladd method for anisotropic\nshapes and thermodynamic integration. The enhanced stability of the approximant\ncan be attributed to a network substructure, which maximizes the free volume\n(and hence the 'wiggle room') available to the particles and facilitates\ncorrelated motion of particles, which further contributes to entropy and leads\nto diffusion for packing densities below 65%. The existence of a solid-solid\ntransition between structurally distinct phases not related by symmetry\nbreaking -- the approximant and the dimer crystal-- is unusual for hard\nparticle systems.",
        "positive": "Reorganization of a granular medium around a localized transformation: Physical and chemical transformation processes in reactive granular media\ninvolve the reorganization of the structure. In this paper, we study\nexperimentally the rearrangements of a two-dimensional (2D) granular packing\nundergoing a localized transformation. We track the position and evolution of\nall the disks that constitute the granular packing when either a large intruder\nshrinks in size or is pulled out of the granular structure. In the two\nsituations the displacements at long time are similar to 2D quasistatic silo\nflows whereas the short-time dynamic is heterogeneous in both space and time.\nWe observe an avalanchelike behavior with power-law distributed events\nuncorrelated in time. In addition, the instantaneous evolutions of the local\nsolid fraction exhibit self-similar distributions. The averages and the\nstandard deviations of the solid fraction variations can be rescaled,\nsuggesting a single mechanism of rearrangement."
    },
    {
        "anchor": "Formation of nematic liquid crystalline phase of F-actin varies from\n  continuous to biphasic transition: We show that the isotropic to nematic liquid crystalline phase transition of\nF-actin can be either continuous or discontinuous, depending critically on the\nfilament length. For F-actin with average filament length > 3 um, we confirm\nthat the transition is continuous in both filament alignment and local\nconcentration. In contrast, for filament length < 2 um the F-actin solution\nundergoes a first order transition. Tactoidal droplets of co-existing isotropic\nand nematic domains were observed. Phenomena of nucleation-and-growth and\nspinodal decomposition both occur, depending sensitively on the exact\nconcentration and average filament length of F-actin. In the late stage, the\ntactoidal droplets continually grow and occasionally coalesce to form larger\ngranules.",
        "positive": "Influence of the time-dependent surfactant adsorption on the lifetime of\n  a drop pressed by buoyancy against a planar interface: Emulsion Stability Simulations (ESS) of deformable droplets are used to study\nthe influence of the time-dependent adsorption on the coalescence time of a\n200-$\\mu$m drop of soybean oil pressed by buoyancy against a planar water/oil\ninterface. The interface is represented by a 5000-$\\mu$m drop of oil fixed in\nthe space. The movement of the small drop is determined by the interaction\nforces between the drops, the buoyancy force, and its thermal interaction with\nthe solvent. The interaction forces depend on the surface concentration of\nsurfactant molecules at the oil/water interfaces. Assuming diffusion limited\nadsorption, the surface excess of the surfactant becomes a function of its\napparent diffusion constant, $D_{app}$. Distinct probability distributions of\nthe coalescence time are obtained depending on the magnitude of $D_{app}$. The\norigin and the significance of these distributions are discussed."
    },
    {
        "anchor": "Squigglebot: a battery powered spherical rolling robot as a model active\n  matter system to measure its energetics: Active matter systems use their internal or ambient source of energy and\ndissipate them at the scale of individual constituent particles to generate\nmotion. Direct measurement of the energy influx for individual particles has\nnot been achieved in the experiments. Here we present \"Squigglebot\" - a battery\npowered spherical rolling robot based on open source hardware as an artificial\nactive matter system whose energy consumption as well as the energy dissipation\ninto different modes of motion both can be measured experimentally. This can\nserve as a prototype system to study a number of interesting problems in\nnon-equilibrium statistical physics, where details of the energetics are\nrequired.",
        "positive": "Molecular Dynamics Study of Charged Dendrimers in Salt-Free Solution:\n  Effect of Counterions: Polyamidoamine (PAMAM) dendrimers, being protonated under physiological\nconditions, represent a promising class of nonviral, nano-sized vectors for\ndrug and gene delivery. We performed extensive molecular dynamics simulations\nof a generic model dendrimer in a salt-free solution with dendrimer's terminal\nbeads positively charged. Solvent molecules as well as counterions were\nexplicitly included as interacting beads. We find that the size of the charged\ndendrimer depends non-monotonically on the strength of electrostatic\ninteractions demonstrating a maximum when the Bjerrum length equals the\ndiameter of a bead. Many other structural and dynamic characteristics of\ncharged dendrimers are also found to follow this pattern. We address such a\nbehavior to the interplay between repulsive interactions of the charged\nterminal beads and their attractive interactions with oppositely charged\ncounterions. The former favors swelling at small Bjerrum lengths and the latter\npromotes counterion condensation. Thus, counterions can have a dramatic effect\non the structure and dynamics of charged dendrimers and, under certain\nconditions, cannot be treated implicitly."
    },
    {
        "anchor": "Simple equation of state for hard disks on the hyperbolic plane: A simple equation of state for hard disks on the hyperbolic plane is\nproposed. It yields the exact second virial coefficient and contains a pole at\nthe highest possible packing. A comparison with another very recent theoretical\nproposal and simulation data is presented.",
        "positive": "Derivation of a hydrodynamic theory for mesoscale dynamics in\n  microswimmer suspensions: In this paper we systematically derive a fourth-order continuum theory\ncapable of reproducing mesoscale turbulence in a three-dimensional suspension\nof microswimmers. We start from overdamped Langevin equations for a generic\nmicroscopic model (pushers or pullers), which include hydrodynamic interactions\non both, small length scales (polar alignment of neighboring swimmers) and\nlarge length scales, where the solvent flow interacts with the order parameter\nfield. The flow field is determined via the Stokes equation supplemented by an\nansatz for the stress tensor. In addition to hydrodynamic interactions, we\nallow for nematic pair interactions stemming from excluded-volume effects. The\nresults here substantially extend and generalize earlier findings [Phys. Rev. E\n94, 020601(R) (2016)], in which we derived a two-dimensional hydrodynamic\ntheory. From the corresponding mean-field Fokker-Planck equation combined with\na self-consistent closure scheme, we derive nonlinear field equations for the\npolar and the nematic order parameter, involving gradient terms of up to fourth\norder. We find that the effective microswimmer dynamics depends on the coupling\nbetween solvent flow and orientational order. For very weak coupling\ncorresponding to a high viscosity of the suspension, the dynamics of mesoscale\nturbulence can be described by a simplified model containing only an effective\nmicroswimmer velocity."
    },
    {
        "anchor": "Steady state extensional rheology of a dilute suspension of spheres in a\n  dilute polymer solution: We investigate the steady-state extensional rheology of a dilute suspension\nof spherical particles in a dilute polymer solution. For a particle-free\npolymeric fluid, in addition to the solvent viscosity, the extensional\nviscosity due to the polymers, $\\mu^\\text{poly}$, contributes to the total\nnon-dimensionalized extensional viscosity $1+\\mu^\\text{poly}$. When a small\nvolume fraction, $\\phi$, of spheres is added to a polymeric fluid, the stress\nis altered by the Einstein viscosity of 2.5$\\phi$ and two additional stress\ncontributions: the interaction stresslet and the particle-induced polymer\nstress (PIPS). The net interaction stress is positive at lower Deborah numbers\n(product of extension rate and polymer relaxation time), $De\\lesssim0.5$, and\nnegative at large $De$. Relative to undisturbed flow, the presence of spheres\nin uniaxial extensional flow creates larger and smaller local stretching\nregions. Below the coil-stretch transition ($De<0.5$), the polymers far from\nthe particles are in a coiled state, and a wake of stretched polymers forms\ndownstream of the particle as they are stretched by the large stretching\nregions around the particle. This leads to a positive interaction stresslet\n(surface) and the PIPS (stretched wake). Beyond the coil-stretch transition,\npolymers far from the particle are highly stretched, but they collapse closer\nto the coiled state as they arrive at the low-stretching regions near the\nparticle surface. Therefore, a negative PIPS results from the regions of\ncollapsed polymers. When $De\\gtrsim0.6$, the changes in extensional viscosity\nfrom the interaction stresslet and the PIPS are $\\phi\\mu^\\text{poly}$ and\napproximately -1.85$\\phi\\mu^\\text{poly}$, respectively. At large $De$, the\npolymer extensional viscosity, $\\mu^\\text{poly}$, is large. Therefore, adding\nparticles reduces the extensional viscosity of the suspension\n($(2.5-0.85\\mu^\\text{poly})\\phi<0$).",
        "positive": "Jaynes-Cummings dynamics with a matter wave oscillator: We propose to subject two Bose-Einstein condensates to a periodic potential,\nso that one condensate undergoes the Mott insulator transition to a state with\nprecisely one atom per lattice site. We show that photoassociation of\nheteronuclear molecules within each lattice site is described by the quantum\noptical Jaynes-Cummings Hamiltonian. In analogy with studies of this\nHamiltonian with cavity fields and trapped ions, we are thus able to engineer\nquantum optical states of atomic matter wave fields and we are able to\nreconstruct these states by quantum state tomography."
    },
    {
        "anchor": "Channel Flow of a Tensorial Shear-Thinning Maxwell Model: Lattice\n  Boltzmann Simulations: We introduce a nonlinear generalized tensorial Maxwell-type constitutive\nequation to describe shear-thinning glass-forming fluids, motivated by a recent\nmicroscopic approach to the nonlinear rheology of colloidal suspensions. The\nmodel captures a nonvanishing dynamical yield stress at the glass transition\nand incorporates normal-stress differences. A modified lattice-Boltzmann (LB)\nsimulation scheme is presented that includes non-Newtonian contributions to the\nstress tensor and deals with flow-induced pressure differences. We test this\nscheme in pressure-driven 2D Poiseuille flow of the nonlinear generalized\nMaxwell fluid. In the steady state, comparison with an analytical solution\nshows good agreement. The transient dynamics after startup and cessation of the\npressure gradient are studied; the simulation reproduces a finite stopping time\nfor the cessation flow of the yield-stress fluid in agreement with previous\nanalytical estimates.",
        "positive": "Interplay of Structure, Elasticity and Dynamics in Actin-Based Nematic\n  Materials: Achieving control and tunability of lyotropic materials has been a\nlong-standing goal of liquid crystal research. Here we show that the elasticity\nof a liquid crystal system consisting of a dense suspension of semiflexible\nbiopolymers can be manipulated over a relatively wide range of elastic moduli.\nSpecifically, thin films of actin filaments are assembled at an oil-water\ninterface. At sufficiently high concentrations, one observes the formation of a\nnematic phase riddled with $\\pm1/2$ topological defects, characteristic of a\ntwo-dimensional nematic system. As the average filament length increases, the\ndefect morphology transitions from a U-shape into a V-shape, indicating the\nrelative increase of the material's bend over splay modulus. Furthermore,\nthrough the sparse addition of rigid microtubule filaments, one can further\ncontrol the liquid crystal elasticity. We show how the material's bend constant\ncan be raised linearly as a function of microtubule filament density, and\npresent a simple means to extract absolute values of the elastic moduli from\npurely optical observations. Finally, we demonstrate that it is possible to\npredict not only the static structure of the material, including its\ntopological defects, but also the evolution of the system into dynamically\narrested states. Despite the non-equilibrium nature of the material, our\ncontinuum model, which couples structure and hydrodynamics, is able to capture\nthe annihilation and movement of defects over long time scales. Thus, we have\nexperimentally realized a lyotropic liquid crystal system that can be truly\nengineered, with tunable mechanical properties, and a theoretical framework to\ncapture its structure, mechanics, and dynamics."
    },
    {
        "anchor": "On the degeneracy of ordered ground state configurations of the\n  aspherical Gaussian core model: We provide rigorous evidence that the ordered ground state configurations of\na system of parallel oriented, ellipsoidal particles, interacting via a\nGaussian interaction (termed in literature as Gaussian core nematics) {\\it\nmust} be infinitely degenerate: we have demonstrated that these configurations\noriginate from the related ground state configuration of the corresponding\nsymmetric Gaussian core system via a suitable stretching operation of this\nlattice in combination with an arbitrary rotation. These findings explain\nrelated observations in former investigations, which then remained unexplained.\nOur conclusions have far reaching consequences for the search of ground state\nconfigurations of other nematic particles.",
        "positive": "Excluded Volume Effects of Branched Molecules: The expansion factor, $\\alpha^{2}=\\langle s_{N}^{2}\\rangle/\\langle\ns_{N}^{2}\\rangle_{0}$, of branched molecules in the melt state is estimated.\nThe equilibrium expansion factor is determined as the point in which all the\ninhomogeneity terms of the osmotic potential, $\\Delta G_{osmotic}$, go to zero.\nNumerical analysis shows that $\\log\\,\\alpha=0.082\\,\\log N+\\text{const.}$ for\n$10^{3}\\le N\\le 10^{7}$, giving $\\alpha\\cong \\text{const.}\\,N^{1/12}$ so that\n$\\langle s_{N}^{2}\\rangle^{1/2}\\propto N^{1/3}$ which coincides with the value\nfor the critical packing density."
    },
    {
        "anchor": "Impact problem for the quasi-linear viscoelastic standard solid model: The one-dimensional impact problem in the case of Fung's quasi-linear\nviscoelastic model is studied for the relaxation function of the standard solid\nmodel (or Zener model). At that, quasi-linear viscoelastic Maxwell and\nKelvin-Voigt models are recovered as limit cases. The results of numerical\nsimulations for some illustrative values of the dimensionless problem\nparameters are presented.",
        "positive": "Meniscus osculation and adsorption on geometrically structured walls: We study the adsorption of simple fluids at smoothly structured, completely\nwet, walls and show that a meniscus osculation transition occurs when the\nLaplace and geometrical radii of curvature of locally parabolic regions\ncoincide. Macroscopically, the osculation transition is of fractional, $7/2$,\norder and separates regimes in which the adsorption is microscopic, containing\nonly a thin wetting layer, and mesoscopic, in which a meniscus exists. We\ndevelop a scaling theory for the rounding of the transition due to thin wetting\nlayers and derive critical exponent relations that determine how the\ninterfacial height scales with the geometrical radius of curvature. Connection\nwith the general geometric construction proposed by Rasc\\'on and Parry is made.\nOur predictions are supported by a microscopic model density functional theory\n(DFT) for drying at a sinusoidally shaped hard-wall where we confirm the order\nof the transition and also an exact sum-rule for the generalized contact\ntheorem due to Upton. We show that as bulk coexistence is approached the\nadsorption isotherm separates into three regimes: a pre-osculation regime where\nit is microscopic, containing only a thin wetting layer, a mesoscopic regime,\nin which a meniscus sits within the troughs, and finally another microscopic\nregime where the liquid-gas interface unbinds from the crests of the substrate."
    },
    {
        "anchor": "Directional Clogging and Phase Separation for Disk Flow Through Periodic\n  and Diluted Obstacle Arrays: We model collective disk flow though a square array of obstacles as the flow\ndirection is changed relative to the symmetry directions of the array. At lower\ndisk densities there is no clogging for any driving direction, but as the disk\ndensity increases, the average disk velocity decreases and develops a drive\nangle dependence. For certain driving angles, the flow is reduced or drops to\nzero when the system forms a heterogeneous clogged state consisting of high\ndensity clogged regions coexisting with empty regions. The clogged states are\nfragile and can be unclogged by changing the driving angle. For large obstacle\nsizes, we find a uniform clogged state that is distinct from the collective\nclogging regime. Within the clogged phases, depinning transitions can occur as\na function of increasing driving force, with strongly intermittent motion\nappearing just above the depinning threshold. The clogging is robust against\nthe random removal or dilution of the obstacle sites, and the disks are able to\nform system-spanning clogged clusters even under increasing dilution. If the\ndilution becomes too large, however, the clogging behavior is lost.",
        "positive": "Collective transport of weakly interacting molecular motors with\n  Langmuir kinetics: Filament based intracellular transport involves the collective action of\nmolecular motor proteins. Experimental evidences suggest that microtubule (MT)\nfilament bound motor proteins such as {\\it kinesins} weakly interact among\nthemselves during transport and with the surrounding cellular environment.\nMotivated by these observations we study a driven lattice gas model for\ncollective unidirectional transport of molecular motors on open filament, which\nincorporates the short-range interactions between the motors on filaments and\ncouples the transport process on filament with surrounding cellular environment\nthrough adsorption-desorption Langmuir (LK) kinetics of the motors. We analyse\nthis model within the framework of a Mean Field (MF) theory in the limit of\n{\\it weak} interactions between the motors. We point to the mapping of this\nmodel with the non-conserved version of Katz-Lebowitz-Spohn (KLS) model. The\nsystem exhibits rich phase behavior with variety of inhomogeneous phases\nincluding localized shocks in the bulk of the filament. We obtain the steady\nstate density and current profiles and analyse their variation as function of\nthe strength of interaction. We compare these MF results with Monte Carlo\nsimulations and find that the MF analysis shows reasonably good agreement as\nlong as the motors are weakly interacting. We also construct the\nnon-equilibrium MF phase diagram."
    },
    {
        "anchor": "The role of attraction in the phase diagrams and melting scenarios of\n  generalized 2D Lennard-Jones systems: Monolayer and two-dimensional (2D) systems exhibit rich phase behavior,\ncompared with 3D systems, in particular, due to the hexatic phase playing a\ncentral role in melting scenarios. The attraction range is known to affect\ncritical gas-liquid behavior (liquid-liquid in protein and colloidal systems),\nbut the effect of attraction on melting in 2D systems remains unstudied\nsystematically. Here, we reveal how the attraction range affects the phase\ndiagrams and melting scenarios in a 2D system. Using molecular dynamics\nsimulations we considered the generalized Lennard-Jones system with a fixed\nrepulsion branch and different power indices of attraction, from long-range\ndipolar to short-range sticky-spheres-like. A drop in the attraction range has\nbeen found to reduce the temperature of the gas-liquid critical point, bringing\nit closer to the gas-liquid-solid triple point. At high-temperatures,\nattraction does not affect the melting scenario that proceeds through the\ncascade of solid-hexatic (Berezinski-Kosterlitz-Thouless) and hexatic-liquid\n(first-order) phase transitions. In the case of dipolar attraction, we observed\n\\emph{two triple points}, inherent in a 2D system: hexatic-liquid-gas and\ncrystal-hexatic-gas, the temperature of the crystal-hexatic-gas triple point is\n\\emph{below} the hexatic-liquid-gas triple point. This observation may have\nfar-reaching consequences for future studies, since phase diagrams determine\npossible routes of self-assembly in molecular, protein, and colloidal systems,\nwhereas the attraction range can be adjusted with complex solvents and external\nelectric or magnetic fields. The results obtained may be widely used in\ncondensed matter, chemical physics, materials science, and soft matter.",
        "positive": "Low temperature electron-spin relaxation in the crystalline and glassy\n  states of solid ethanol: X-band electron paramagnetic resonance (EPR) spectroscopy was used to study\nthe spectral properties of a nitroxide spin probe in ethanol glass and\ncrystalline ethanol, at 5 - 11.5 K. The different anisotropy of molecular\npacking in the two host matrices was evidenced by different rigid limit values\nfor maximal hyperfine splitting in the signal of the spin probe. The\nsignificantly shorter phase memory time, , for the spin probe dissolved in\ncrystalline ethanol, as compared to ethanol glass, was discussed in terms of\ncontribution from spectral diffusion. The effect of low-frequency dynamics was\nmanifested in the temperature dependence of and in the difference between the\ndata measured at different spectral positions. This phenomenon was addressed\nwithin the framework of the slow-motional isotropic diffusion model [S. Lee,\nand S. Z. Tang, Phys. Rev. B 31, 1308 (1985)] predicting the spin probe\ndynamics within the millisecond range, at very low temperatures. The shorter\nspin-lattice relaxation time of the spin probe in ethanol glass was interpreted\nin terms of enhanced energy exchange between the spin system and the lattice in\nthe glass matrix due to boson peak excitations."
    },
    {
        "anchor": "Coarsening of topological defects in 2D polar active matter: We numerically study the coarsening of topological defects in 2D polar active\nmatter and make several interesting observations and predictions. (i) The long\ntime state is characterized by nonzero density of defects, in stark contrast to\ntheoretical expectations. (ii) The kinetics of defect coarsening shows power\nlaw decay to steady state, as opposed to exponential decay in thermal\nequilibrium. (iii) Observations (i) and (ii) together suggest emergent\nscreening of topological charges due to activity. (iv) Nontrivial defect\ncoarsening in the active model leads to nontrivial steady state patterns. We\ninvestigate, characterize, and validate these patterns and discuss their\nbiological significance.",
        "positive": "Moving, reproducing, and dying beyond Flatland: Malthusian flocks in\n  dimensions $d>2$: We show that \"Malthusian flocks\" -- i.e., coherently moving collections of\nself-propelled entities (such as living creatures) which are being \"born\" and\n\"dying\" during their motion -- belong to a new universality class in spatial\ndimensions $d>2$. We calculate the universal exponents and scaling laws of this\nnew universality class to $O(\\epsilon)$ in an $\\epsilon=4-d$ expansion, and\nfind these are different from the \"canonical\" exponents previously conjectured\nto hold for \"immortal\" flocks (i.e., those without birth and death) and shown\nto hold for incompressible flocks in $d>2$. Our expansion should be quite\naccurate in $d=3$, allowing precise quantitative comparisons between our\ntheory, simulations, and experiments."
    },
    {
        "anchor": "Molecular diffusion between walls with adsorption and desorption: The time dependency of the diffusion coefficient of particles in porous media\nis an efficient probe of their geometry. The analysis of this quantity,\nmeasured e.g. by nuclear magnetic resonance (PGSE-NMR), can provide rich\ninformation pertaining to porosity, pore size distribution, permeability and\nsurface-to-volume ratio of porous materials. Nevertheless, in numerous if not\nall practical situations, transport is confined by walls where adsorption and\ndesorption processes may occur. In this article, we derive explicitly the\nexpression of the time-dependent diffusion coefficient between two confining\nwalls in the presence of adsorption and desorption. We show that they strongly\nmodify the time-dependency of the diffusion coefficient, even in this simple\ngeometry. We finally propose several applications, from sorption rates\nmeasurements to the use as a reference for numerical implementations for more\ncomplex geometries.",
        "positive": "Increase of SRG modulation depth in azopolymers-nanoparticles hybrid\n  materials: Thin films of azopolymer-nanoparticles hybrid materials were fabricated with\npoly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl]\n(PAZO) and different concentrations of Ag and AgAu nanoparticles (NPs). By\nilluminating the films with polarized interference patterns, surface relief\ngratings (SRGs) were recorded. It was found that for some concentrations of NPs\ntheir modulations and diffraction efficiency were higher than the obtained for\nPAZO films without NPs. The effect was mainly explained by the increase of the\nfree volume available for the photoisomerization for certain concentrations of\nNPs. The dependence of the diffraction efficiency on concentration was directly\nrelated to changes in modulation depth. When doping with NPs, the maximum\nefficiency increases more than two times the efficiency without NPs."
    },
    {
        "anchor": "Coil Dimensions as a Function of Concentration: The preceding theory of excluded volume effects is applied to the Daud and\ncoworkers' observations. Based on various researchers' experimental data, it is\nsuggested that the Daud and coworkers' value in the bulk state may be revised\nfrom 82 \\AA to 93\\AA. Then agreement between the theory and the revised data is\nexcellent, giving a support to the preceding result that the excluded volume\neffects should vanish at medium concentration.",
        "positive": "Perspectives on the viscoelasticity and flow behavior of entangled\n  linear and branched polymers: We briefly review the recent advances in the rheology of entangled polymers\nand identify emerging research trends and outstanding challenges, especially\nwith respect to branched polymers. Emphasis is placed on the role of\nwell-characterized model systems, as well as the synergy of\nsynthesis-characterization, rheometry and modeling/simulations. The theoretical\nframework for understanding the observed linear and nonlinear rheological\nphenomena is the tube model which is critically assessed in view of its\nsuccesses and shortcomings, whereas alternative approaches are briefly\ndiscussed. Finally, intriguing experimental findings and controversial issues\nthat merit consistent explanation, such as shear banding instabilities,\nmultiple stress overshoots in transient simple shear and enhanced steady-state\nelongational viscosity in polymer solutions, are discussed, whereas future\ndirections such as branch point dynamics and anisotropic monomeric friction are\noutlined."
    },
    {
        "anchor": "Logarithmic vs Andrade's transient creep: the role of elastic stress\n  redistribution: Creep is defined as time-dependent deformation and rupture processes taking\nplace within a material subjected to a constant applied stress smaller than its\nathermal, time-independent strength. This time-dependence is classically\nattributed to thermal activation of local deformation events. The phenomenology\nof creep is characterized by several ubiquitous but empirical rheological and\nscaling laws. We focus here on primary creep following the onset of loading,\nfor which a power law decay of the strain-rate is observed, with the exponent p\nvarying between '0.4 and 1, this upper bound defining the so-called logarithmic\ncreep. Although this phenomenology is known for more than a century, the\nphysical origin of Andrade-like (p <1) creep remains unclear and debated. Here\nwe show that p <1 values arise from the interplay between thermal activation\nand elastic stress redistribution. The latter stimulates creep dynamics from a\nshortening of waiting times between successive events, is associated to\nmaterial damage and possibly, at high temperature and/or stresses, gives rise\nto avalanches of deformation events.",
        "positive": "Nucleation in sheared granular matter: We present an experiment on crystallization of packings of macroscopic\ngranular spheres. This system is often considered to be a model for thermally\ndriven atomic or colloidal systems. Cyclically shearing a packing of frictional\nspheres, we observe a first order phase transition from a disordered to an\nordered state. The ordered state consists of crystallites of mixed FCC and HCP\nsymmetry that coexist with the amorphous bulk. The transition, initiated by\nhomogeneous nucleation, overcomes a barrier at 64.5% volume fraction.\nNucleation consists predominantly of the dissolving of small nuclei and the\ngrowth of nuclei that have reached a critical size of about ten spheres."
    },
    {
        "anchor": "Wall slip and flow of concentrated hard-sphere colloidal suspensions: We present a comprehensive study of the slip and flow of concentrated\ncolloidal suspensions using cone-plate rheometry and simultaneous confocal\nimaging. In the colloidal glass regime, for smooth, non-stick walls, the solid\nnature of the suspension causes a transition in the rheology from\nHerschel-Bulkley (HB) bulk flow behavior at large stress to a Bingham-like slip\nbehavior at low stress, which is suppressed for sufficient colloid-wall\nattraction or colloid-scale wall roughness. Visualization shows how the\nslip-shear transition depends on gap size and the boundary conditions at both\nwalls and that partial slip persist well above the yield stress. A\nphenomenological model, incorporating the Bingham slip law and HB bulk flow,\nfully accounts for the behavior. Microscopically, the Bingham law is related to\na thin (sub-colloidal) lubrication layer at the wall, giving rise to a\ncharacteristic dependence of slip parameters on particle size and\nconcentration. We relate this to the suspension's osmotic pressure and yield\nstress and also analyze the influence of van der Waals interaction. For the\nlargest concentrations, we observe non-uniform flow around the yield stress, in\nline with recent work on bulk shear-banding of concentrated pastes. We also\ndescribe residual slip in concentrated liquid suspensions, where the vanishing\nyield stress causes coexistence of (weak) slip and bulk shear flow for all\nmeasured rates.",
        "positive": "Dynamics of elastic, nonheavy spheres sedimenting in a rectangular duct: Understanding of sedimentation dynamics of particles in bounded fluids is of\ncrucial importance for a wide variety of processes. While there is profound\nknowledge base regarding the sedimentation of rigid solid particles, the\nfundamental principles of sedimentation dynamics of elastic, nonheavy spheres\nin bounded fluids are not well understood. Therefore, we performed\nsedimentation of deformable, elastic solid spheres with particle Reynolds\nnumbers much smaller than 1 in a model experiment. The spheres started from\nrest in a rectangular duct with a width of about 23 times the radius R of the\nsphere. The particle dynamics of elastic spheres differed fundamentally from\nthat of rigid spheres. Elastic effects were found to take place on\ncomparatively large time scales, such that elastic spheres underwent four\nphases of sedimentation. Phases I and II, including transient acceleration and\na short steady velocity plateau, are comparable with sedimentation of rigid\nspheres. From a characteristic onset position of about 10R, deformability\neffects kick in and a second acceleration appears (phase III). In the fourth\nphase, the deformable spheres reach the terminal sedimentation velocity. The\nsofter the spheres are, the higher the terminal velocity is. In the present\nsetup, a terminal velocity up to 9 percent higher than the velocity for\ncomparable rigid spheres was reached. By means of the obtained data, insights\ninto the dynamics are given that could serve as basic approaches for modelling\nthe dynamics of elastic spheres in bounded fluids."
    },
    {
        "anchor": "ArGSLab: A tool for analyzing experimental or simulated particle\n  networks: Microscopy and particle-based simulations are both powerful techniques to\nstudy aggregated particulate matter such as colloidal gels. The data provided\nby these techniques often contains information on a wide array of length\nscales, but structural analysis methods typically focus on the local particle\narrangement, even though the data also contains information about the particle\nnetwork on the mesoscopic length scale. In this paper, we present a MATLAB\nsoftware package for quantifying mesoscopic network structures in colloidal\nsamples. ArGSLab (Arrested and Gelated Structures Laboratory) extracts a\nnetwork backbone from the input data, which is in turn transformed into a set\nof nodes and links for graph theory-based analysis. The routines can process\nboth image stacks from microscopy as well as explicit coordinate data, and thus\nallows quantitative comparison between simulations and experiments. ArGSLab\nfurthermore enables the accurate analysis of microscopy data where, e.g., an\nextended point spread function prohibits the resolution of individual\nparticles. We demonstrate the resulting output for example datasets from both\nmicroscopy and simulation of colloidal gels, in order to showcase the\ncapability of ArGSLab to quantitatively analyze data from various sources. The\nfreely available software package can be used either with a provided graphical\nuser interface or directly as a MATLAB script.",
        "positive": "Engineering azeotropy to optimize the self-assembly of colloidal\n  mixtures: The goal of inverse self-assembly is to design inter-particle interactions\ncapable of assembling the units into a desired target structure. The effective\nassembly of complex structures often requires the use of multiple components,\neach new component increasing the thermodynamic degrees of freedom and hence\nthe complexity of the self-assembly pathway. In this work we explore the\npossibility to use azeotropy, i.e. a special thermodynamic condition where the\nsystem behaves effectively as a one-component system, as a way to control the\nself-assembly of an arbitrarily number of components. Exploiting the\nmass-balance equations we show how to select patchy particle systems that\nexhibit azeotropic points along the desired self-assembly pathway. As an\nexample we map the phase diagram of a binary mixture that, by design, fully\nassembles into cubic (and only cubic) diamond crystal via an azeotropic point.\nThe ability to explicitly include azeotropic points into artificial designs\nopens novel pathways to the self-assembly of complex structures."
    },
    {
        "anchor": "Emergent reprogrammable mechanical memory in soft rods network via\n  friction tuning: We present emergent mechanical memory storage behavior in soft cellular\nmaterials. The cellular materials are a network of soft hyperelastic rods which\nstore shape changes, specifically local indentation. This happens under an\napplied global compressive strain on the material. The material transits under\nstrain from an elastic state (capable of `forgetting' any applied indentation\nafter un-indentation) to plastic state (indefinitely storing the shape change\ndue to indentation). The memory can be erased via removal of applied global\nstrains and is therefore re-programmable. We characterise this behaviour\nexperimentally and present a simple model that makes use of friction for\nunderstanding this behavior.",
        "positive": "Novel chiral smectic phase generation in systems of polar ellipsoidal\n  molecules with reflection asymmetry: A molecular dynamics simulation study: Computer simulation study of phase transitional behaviour of cholesterol\nmolecules embedded with terminal dipole is reported. In this work,\ncoarse-grained modeling of cholesteric molecules is done to study the influence\nof the coupled chiral and dipolar interactions on macroscopic\nliquid-crystalline phase formation. This NVT molecular dynamics simulation\nstudy demonstrates the formaton of novel Smectic Blue phase\n(BP\\textsubscript{Sm}) which is a recent experimentally discovered chiral\nphase. Our study reveals that the higher strength of chiral interaction induces\nblue phase, whereas, larger dipolar interaction can bring bilayered smectic\nblue phase."
    },
    {
        "anchor": "Electrons in Dry DNA from Density Functional Calculations: The electronic structure of an infinite poly-guanine - poly-cytosine DNA\nmolecule in its dry A-helix structure is studied by means of density-functional\ncalculations. An extensive study of 30 nucleic base pairs is performed to\nvalidate the method. The electronic energy bands of DNA close to the Fermi\nlevel are then analyzed in order to clarify the electron transport properties\nin this particularly simple DNA realization, probably the best suited candidate\nfor conduction. The energy scale found for the relevant band widths, as\ncompared with the energy fluctuations of vibrational or genetic-sequence\norigin, makes highly implausible the coherent transport of electrons in this\nsystem. The possibility of diffusive transport with sub-nanometer mean free\npaths is, however, still open. Information for model Hamiltonians for\nconduction is provided.",
        "positive": "Modeling Leidenfrost levitation of soft elastic solids: The elastic Leidenfrost effect occurs when a vaporizable soft solid is\nlowered onto a hot surface. Evaporative flow couples to elastic deformation,\ngiving spontaneous bouncing or steady-state floating. The effect embodies an\nunexplored interplay between thermodynamics, elasticity, and lubrication:\ndespite being observed, its basic theoretical description remains a challenge.\nHere, we provide a theory of elastic Leidenfrost floating. As weight increases,\na rigid solid sits closer to the hot surface. By contrast, we discover an\nelasticity-dominated regime where the heavier the solid, the higher it floats.\nThis geometry-governed behavior is reminiscent of the dynamics of large liquid\nLeidenfrost drops. We show that this elastic regime is characterized by\nHertzian behavior of the solid's underbelly and derive how the float height\nscales with materials parameters. Introducing a dimensionless elastic\nLeidenfrost number, we capture the crossover between rigid and Hertzian\nbehavior. Our results provide theoretical underpinning for recent experiments,\nand point to the design of novel soft machines."
    },
    {
        "anchor": "Multi-Ciliated Microswimmers -- Metachronal Coordination and Helical\n  Swimming: The dynamics and motion of multi-ciliated microswimmers with a spherical body\nand a small number N (with 5 < N < 60) of cilia with length comparable to the\nbody radius, is investigated by mesoscale hydrodynamics simulations. A\nmetachronal wave is imposed for the cilia beat, for which the wave vector has\nboth a longitudinal and a latitudinal component. The dynamics and motion is\ncharacterized by the swimming velocity, its variation over the beat cycle, the\nspinning velocity around the main body axis, as well as the parameters of the\nhelical trajectory. Our simulation results show that the microswimmer motion\nstrongly depends on the latitudinal wave number and the longitudinal phase lag.\nThe microswimmers are found to swim smoothly and usually spin around their own\naxis. Chirality of the metachronal beat pattern generically generates helical\ntrajectories. In most cases, the helices are thin and stretched, i.e. the helix\nradius is about an order of magnitude smaller than the pitch. The rotational\ndiffusion of the microswimmer is significantly smaller than the passive\nrotational diffusion of the body alone, which indicates that the extended cilia\ncontribute strongly to the hydrodynamic radius. The swimming velocity vswim is\nfound to increase with the cilia number N with a slightly sublinear power law,\nconsistent with the behavior expected from the dependence of the transport\nvelocity of planar cilia arrays on the cilia separation.",
        "positive": "Structure and stability of charged clusters: When a cluster or nanodroplet bears charge, its structure and thermodynamics\nare altered and, if the charge exceeds a certain limit, the system becomes\nunstable with respect to fragmentation. Some of the key results in this area\nwere derived by Rayleigh in the nineteenth century using a continuum model of\nliquid droplets. Here we revisit the topic using a simple particle-based\ndescription, presenting a systematic case study of how charge affects the\nphysical properties of a Lennard-Jones cluster composed of 309 particles. We\nfind that the ability of the cluster to sustain charge depends on the number of\nparticles over which the charge is distributed---a parameter not included in\nRayleigh's analysis. Furthermore, the cluster may fragment before the charge is\nstrong enough to drive all charged particles to the surface. The charged\nparticles in stable clusters are therefore likely to reside in the cluster's\ninterior even without considering solvation effects."
    },
    {
        "anchor": "Coupled elasticity in soft solid foams: Elasticity of soft materials can be greatly influenced by the presence of air\nbubbles. Such a capillary effect is expected for a wide range of materials,\nfrom polymer gels to concentrated emulsions and colloidal suspensions. Whereas\nexperimental results and theory exist for describing the elasto-capillary\nbehavior of bubbly materials (i.e. with moderate gas volume fractions), foamy\nsystems still require a dedicated study in order to increase our understanding\nof elasticity in aerated materials over the full range of gas volume fractions.\nHere we elaborate well-controlled foams with concentrated emulsion and we\nmeasure their shear elastic modulus as a function of gas fraction, bubble size\nand elastic modulus of the emulsion. Such complex foams possess the elastic\nfeatures of both the bubble assembly and the interstitial matrix. Moreover,\ntheir elastic modulus is shown to be governed by two parameters, namely the gas\nvolume fraction and the elasto-capillary number, defined as the ratio of the\nemulsion modulus with the bubble capillary pressure. We connect our results for\nfoams with existing data for bubbly systems and we provide a general view for\nthe effect of gas bubbles in soft elastic media. Finally, we suggest that our\nresults could be useful for estimating the shear modulus of aqueous foams and\nemulsions with multimodal size distributions.",
        "positive": "Explicit formulas for reaction probability in reaction-diffusion\n  experiments: A computational procedure is developed for determining the conversion\nprobability for reaction-diffusion systems in which a first-order catalytic\nreaction is performed over active particles. We apply this general method to\nsystems on metric graphs, which may be viewed as 1-dimensional approximations\nof 3-dimensional systems, and obtain explicit formulas for conversion. We then\nstudy numerically a class of 3-dimensional systems and test how accurately they\nare described by model formulas obtained for metric graphs. The optimal\narrangement of active particles in a 1-dimensional multiparticle system is\nfound, which is shown to depend on the level of catalytic activity: conversion\nis maximized for low catalytic activity when all particles are bunched together\nclose to the point of gas injection, and for high catalytic activity when the\nparticles are evenly spaced."
    },
    {
        "anchor": "Center of mass rotation and vortices in an attractive Bose gas: The rotational properties of an attractively interacting Bose gas are studied\nusing analytical and numerical methods. We study perturbatively the ground\nstate phase space for weak interactions, and find that in an anharmonic trap\nthe rotational ground states are vortex or center of mass rotational states;\nthe crossover line separating these two phases is calculated. We further show\nthat the Gross-Pitaevskii equation is a valid description of such a gas in the\nrotating frame and calculate numerically the phase space structure using this\nequation. It is found that the transition between vortex and center of mass\nrotation is gradual; furthermore the perturbative approach is valid only in an\nexceedingly small portion of phase space. We also present an intuitive picture\nof the physics involved in terms of correlated successive measurements for the\ncenter of mass state.",
        "positive": "Interactions between Zwitterionic Membranes in Complex Electrolytes: We investigate the electrostatic interactions of zwitterionic membranes\nimmersed in mixed electrolytes composed of mono- and multivalent ions. We show\nthat the presence of monovalent salt is a necessary condition for the existence\nof a finite electrostatic force on the membrane. As a result, the mean-field\nmembrane pressure originating from the surface dipoles exhibits a non-uniform\nsalt dependence, characterized by an enhancement for dilute salt conditions and\na decrease at intermediate salt concentrations. Upon addition of multivalent\ncations to the submolar salt solution, the separate interactions of these\ncations with the opposite charges of the surface dipoles makes the\nintermembrane pressure more repulsive at low membrane separation distances and\nstrongly attractive at intermediate distances, resulting in a discontinuous\nlike-charge binding transition followed by the membrane binding transition. By\nextending our formalism to account for correlation corrections associated with\nlarge salt concentrations, we show that membranes of high surface dipole\ndensity immersed in molar salt solutions may undergo a membrane binding\ntransition even without the multivalent cations. Hence, the tuning of the\nsurface polarization forces by membrane engineering can be an efficient way to\nadjust the equilibrium configuration of dipolar membranes in concentrated salt\nsolutions."
    },
    {
        "anchor": "Stoneley waves and interface stability of Bell materials in compression;\n  Comparison with rubber: Two semi-infinite bodies made of prestressed, homogeneous, Bell-constrained,\nhyperelastic materials are perfectly bonded along a plane interface. The\nhalf-spaces have been subjected to finite pure homogeneous predeformations,\nwith distinct stretch ratios but common principal axes, and such that the\ninterface is a common principal plane of strain. Constant loads are applied at\ninfinity to maintain the deformations and the influence of these loads on the\npropagation of small-amplitude interface (Stoneley) waves is examined. In\nparticular, the secular equation is found and necessary and sufficient\nconditions to be satisfied by the stretch ratios to ensure the existence of\nsuch waves are given. As the loads vary, the Stoneley wave speed varies\naccordingly: the upper bound is the `limiting speed' (given explicitly), beyond\nwhich the wave amplitude cannot decay away from the interface; the lower bound\nis zero, where the interface might become unstable. The treatment parallels the\none followed for the incompressible case and the differences due to the Bell\nconstraint are highlighted. Finally, the analysis is specialized to specific\nstrain energy densities and to the case where the bimaterial is uniformly\ndeformed (that is when the stretch ratios for the upper half-space are equal to\nthose for the lower half-space.) Numerical results are given for `simple\nhyperelastic Bell' materials and for `Bell's empirical model' materials, and\ncompared to the results for neo-Hookean incompressible materials.",
        "positive": "Breakdown of The Excess Entropy Scaling for the Systems with\n  Thermodynamic Anomalies: This articles presents a simulation study of the applicability of the\nRosenfeld entropy scaling to the systems which can not be approximated by\neffective hard spheres. Three systems are studied: Herzian spheres, Gauss Core\nModel and soft repulsive shoulder potential. These systems demonstrate the\ndiffusion anomalies at low temperatures: the diffusion increases with\nincreasing density or pressure. It is shown that for the first two systems\nwhich belong to the class of bounded potentials the Rosenfeld scaling formula\nis valid only in the infinite temperature limit where there are no anomalies.\nFor the soft repulsive shoulder the scaling formula is valid already at\nsufficiently low temperatures, however, out of the anomaly range."
    },
    {
        "anchor": "Branched Polymers with Excluded Volume Effects/ Configurations of Comb\n  Polymers in Two- and Three-dimensions: We investigate the excluded volume effects in good solvents for the isolated\ncomb polymers having $\\nu_{0}=1/4$. In particular, we investigate the change of\nthe size exponent, $\\nu$, defined by $\\langle s_{N}^{2}\\rangle\\propto\nN^{2\\nu}$, for the various fully-expanded configurations. The results show\nthat, given the fully stretched backbone and side chains, the exponent takes\nthe value, $\\nu=1/2$, irrespective of the configurational isomerization of side\nchains; only the pre-exponential factor changes.",
        "positive": "Semiflexible polymers under external fields confined to two dimensions: The non-equilibrium structural and dynamical properties of semiflexible\npolymers confined to two dimensions are investigated by molecular dynamics\nsimulations. Three different scenarios are considered: The force-extension\nrelation of tethered polymers, the relaxation of an initially stretched\nsemiflexible polymer, and semiflexible polymers under shear flow. We find\nquantitative agreement with theoretical predictions for the force-extension\nrelation and the time dependence of the entropically contracting polymer. The\nsemiflexible polymers under shear flow exhibit significant conformational\nchanges at large shear rates, where less stiff polymers are extended by the\nflow, whereas rather stiff polymers are contracted. In addition, the polymers\nare aligned by the flow, thereby the two-dimensional semiflexible polymers\nbehave similarly to flexible polymers in three dimensions. The tumbling times\ndisplay a power-law dependence at high shear rate rates with an exponent\ncomparable to the one of flexible polymers in three-dimensional systems."
    },
    {
        "anchor": "Revisiting Surface Diffusion in Random Deposition: An investigation of the effect of surface diffusion in random deposition\nmodel is made by analytical methods and reasoning. For any given site, the\nextent to which a particle can diffuse is decided by the morphology in the\nimmediate neighbourhood of the site. An analytical expression is derived to\ncalculate the probability of a particle at any chosen site to diffuse to a\ngiven length, from first principles. Using the method, the probabilities for\ndifferent diffusion lengths are calculated and their dependence on system size\nand the number of deposited layers is studied. Numerical simulation of surface\ndiffusion in random deposition model with varying extents of diffusion are\nperformed and their results are interpreted in the light of the analytical\ncalculations. Thus, a clearer understanding of the diffusion process and the\neffect of diffusion length on surface roughness is obtained. Systems with\nsurface diffusion show nearly random deposition-like behaviour upto monolayer\ndeposition. Their interface widths, in a logarithmic plot, are initially\nlinear, as in random deposition. With increase in the number of layers,\ncorrelation effects between neighbouring columns become dominant. The interface\ndeviates from its initial linear growth and eventually becomes saturated. An\nexplanation for this behaviour is discussed and the point of departure from the\nlinear form is estimated analytically.",
        "positive": "Time-Dependent Density-Functional Theory for Trapped\n  Strongly-Interacting Fermionic Atoms: The dynamics of strongly interacting trapped dilute Fermi gases (dilute in\nthe sense that the range of interatomic potential is small compared with\ninter-particle spacing) is investigated in a single-equation approach to the\ntime-dependent density-functional theory. Our results are in good agreement\nwith recent experimental data in the BCS-BEC crossover regime. It is also shown\nthat the calculated corrections to the hydrodynamic approximation may be\nimportant even for systems with a rather large number of atoms."
    },
    {
        "anchor": "Cosolute partitioning in polymer networks: Effects of flexibility and\n  volume transitions: We study the partitioning of cosolute particles in a thin film of a\nsemi-flexible polymer network by a combination of coarse-grained\n(implicit-solvent) stochastic dynamics simulations and mean-field theory. We\nfocus on a wide range of solvent qualities and cosolute-network interactions\nfor selected polymer flexibilities. Our investigated ensemble\n(isothermal-isobaric) allows the network to undergo a volume transition from\nextended to collapsed state while the cosolutes can distribute in bulk and\nnetwork, correspondingly. We find a rich topology of equilibrium states of the\nnetwork and transitions between them, qualitatively depending on solvent\nquality, polymer flexibility, and cosolute-network interactions. In particular,\nwe find a novel `cosolute-induced' collapsed state, where strongly attractive\ncosolutes bridge network monomers albeit the latter interact mutually\nrepulsive. Finally, the cosolutes' global partitioning `landscape', computed as\na function of solvent quality and cosolute-network interactions, exhibits very\ndifferent topologies depending on polymer flexibility. The simulation results\nare supported by theoretical predictions obtained with a two-component\nmean-field approximation for the Helmholtz free energy that considers the chain\nelasticity and the particle interactions in terms of a virial expansion. Our\nfindings have implications on the interpretation of transport processes and\npermeability in hydrogel films, as realized in filtration or macromolecular\ncarrier systems.",
        "positive": "Realisation of the Brazil-nut effect in charged colloids without\n  external driving: Sedimentation is a ubiquitous phenomenon across many fields of science, such\nas geology, astrophysics, and soft matter. Sometimes, sedimentation leads to\nunusual phenomena, such as the Brazil-nut effect, where heavier (granular)\nparticles reside on top of lighter particles after shaking. We show\nexperimentally that a Brazil-nut effect can be realised in a binary colloidal\nsystem of long-range repulsive charged particles driven purely by Brownian\nmotion and electrostatics without the need for activity. Using theory, we argue\nthat not only the mass-per-charge for the heavier particles needs to be smaller\nthan the mass-per-charge for the lighter particles, but that at high overall\ndensity, the system can be trapped in a long-lived metastable state, which\nprevents the occurrence of the equilibrium Brazil-nut effect. Therefore, we\nenvision that our work provides valuable insights into the physics of strongly\ninteracting systems, such as partially glassy and crystalline structures.\nFinally, our theory, which quantitatively agrees with the experimental data,\npredicts that the shapes of sedimentation density profiles of multicomponent\ncharged colloids are greatly altered when the particles are charge regulating\nwith more than two ion species involved. Hence, we hypothesise that\nsedimentation experiments can aid in revealing the type of ion-adsorption\nprocesses that determine the particle charge and possibly the value of the\ncorresponding equilibrium constants."
    },
    {
        "anchor": "Confinement Stabilizes a Bacterial Suspension into a Spiral Vortex: Confining surfaces play crucial roles in dynamics, transport and order in\nmany physical systems, but their effects on active matter, a broad class of\ndynamically self-organizing systems, are poorly understood. We investigate here\nthe influence of global confinement and surface curvature on collective motion\nby studying the flow and orientational order within small droplets of a dense\nbacterial suspension. The competition between radial confinement,\nself-propulsion, steric interactions and hydrodynamics robustly induces an\nintriguing steady single-vortex state, in which cells align in\ninwardly-spiralling patterns accompanied by a thin counterrotating boundary\nlayer. A minimal continuum model is shown to be in good agreement with these\nobservations.",
        "positive": "Accumulation and depletion of E. coli in surfaces mediated by curvature: Can topography be used to control bacteria accumulation? We address this\nquestion in the model system of smooth-swimming and run-and-tumble\n\\textit{Escherichia coli} swimming near a sinusoidal surface, and show that the\naccumulation of bacteria is determined by the characteristic curvature of the\nsurface. For low curvatures, cells swim along the surface due to steric\nalignment and are ejected from the surface when they reach the peak of the\nsinusoid. Increasing curvature enhances this effect and reduces the density of\nbacteria in the curved surface. However, for curvatures larger than\n$\\kappa^*\\approx 0.3 \\mu m^{-1}$, bacteria become trapped in the valleys, where\nthey can remain for long periods of time. Minimal simulations considering only\nsteric interactions with the surface reproduce these results and give insights\ninto the physical mechanisms defining the critical curvature, which is found to\nscale with the inverse of the bacterial length. We show that for curvatures\nlarger than $\\kappa^*$, the otherwise stable alignment with the wall becomes\nunstable while the stable orientation is now perpendicular to the wall, thus\npredicting accurately the onset of trapping at the valleys."
    },
    {
        "anchor": "Euler-Plateau, with a twist: A generalization of the Euler-Plateau problem to account for the energy\ncontribution due to twisting of the bounding loop is proposed. Euler-Lagrange\nequations are derived in a parameterized setting and a bifurcation analysis is\nperformed. A pair of dimensionless parameters govern bifurcations from a flat,\ncircular ground state. While one of these is familiar from the Euler-Plateau\nproblem, the other encompasses information about the ratio of the twisting to\nbending rigidities, twist, and size of the loop. For sufficiently small values\nof the latter parameter, two separate groups of bifurcation modes are\nidentified. On the other hand, for values greater than the critical twist\narising in Michell's problem of the bifurcation of a twisted annular ring, only\none bifurcation mode exists. Bifurcation diagrams indicate that a loop with\ngreater twisting rigidity shows more resistance to transverse buckling.\nHowever, a twisted and closed filament spanned by a surface endowed with\nuniform surface tension buckles at a twist less than the critical value for an\nelastic ring.",
        "positive": "Surfactant micelles: model systems for flow instabilities of complex\n  fluids: Complex fluids such as emulsions, colloidal gels, polymer or surfactant\nsolutions are all characterized by the existence of a \"microstructure\" which\nmay couple to an external flow on timescales that are easily probed in\nexperiments. Such a coupling between flow and microstructure usually leads to\ninstabilities under relatively weak shear flows that correspond to vanishingly\nsmall Reynolds numbers. Wormlike micellar surfactant solutions appear as model\nsystems to study two examples of such instabilities, namely shear banding and\nelastic instabilities. Focusing on a semidilute sample we show that two\ndimensional ultrafast ultrasonic imaging allows for a thorough investigation of\nunstable shear-banded micellar flows. In steady state, radial and azimuthal\nvelocity components are recovered and unveil the original structure of the\nvortical flow within an elastically unstable high shear rate band. Furthermore\nthanks to an unprecedented frame rate of up to 20,000 fps, transients and fast\ndynamics can be resolved, which paves the way for a better understanding of\nelastic turbulence."
    },
    {
        "anchor": "Cooling and aggregation in wet granulates: Wet granular materials are characterized by a defined bond energy in their\nparticle interaction such that breaking a bond implies an irreversible loss of\na fixed amount of energy. Associated with the bond energy is a nonequilibrium\ntransition, setting in as the granular temperature falls below the bond energy.\nThe subsequent aggregation of particles into clusters is shown to be a\nself-similar growth process with a cluster size distribution that obeys\nscaling. In the early phase of aggregation the clusters are fractals with\nD_f=2, for later times we observe gelation. We use simple scaling arguments to\nderive the temperature decay in the early and late stages of cooling and verify\nour results with event-driven simulations.",
        "positive": "Intermittency, aging and record fluctuations: Aging in spin glasses is analyzed via the Probability Density Function (PDF)\nof the heat transfer between system and bath over a small time $\\delta t$. The\nPDF contains a Gaussian part, describing reversible fluctuations, and an\nexponential tail caused by intermittent events. We find that the relative\nweight of these two parts depends, for fixed $\\delta t$, on the ratio of the\ntotal sampling time to the age $t_w$. Fixing this ratio, the intensity of the\nintermittent events is proportional to $\\delta t/t_w$ and independent of the\ntemperature. The Gaussian part has a variance with the same temperature\ndependence as the variance of the equilibrium energy in a system with an\nexponential density of states. All these observations are explained assuming\nthat, for any $t_w$, intermittent events are triggered by local energy\nfluctuations exceeding those previously occurred."
    },
    {
        "anchor": "Axisymmetric necking versus Treloar-Kearsley instability in a\n  hyperelastic sheet under equibiaxial stretching: We consider bifurcations from the homogeneous solution of a circular or\nsquare hyperelastic sheet that is subjected to equibiaxial stretching under\neither force- or displacement-controlled edge conditions. We derive the\ncondition for axisymmetric necking and show, for the class of strain-energy\nfunctions considered, that the critical stretch for necking is greater than the\ncritical stretch for the Treloar-Kearsley (TK) instability and less than the\ncritical stretch for the limiting-point instability. An amplitude equation for\nthe bifurcated necking solution is derived through a weakly nonlinear analysis\nand is used to show that necking initiation is generally sub-critical. Abaqus\nsimulations are conducted to verify the bifurcation conditions and the\nexpectation that the TK instability should occur first under force control, but\nwhen the edge displacement is controlled the TK instability is suppressed, and\nit is the necking instability that will be observed. It is also demonstrated\nthat axisymmetric necking follows a growth/propagation process typical of all\nsuch localization problems.",
        "positive": "Force renormalization for probes immersed in an active bath: Langevin equations or generalized Langevin equations (GLEs) are popular\nmodels for describing the motion of a particle in a fluid medium in an\neffective manner. Here we examine particles immersed in an inherently\nnonequilibrium fluid, i.e., an active bath, which are subject to an external\nforce. Specifically, we consider two types of forces that are highly relevant\nfor microrheological studies: A harmonic, trapping force and a constant, \"drag\"\nforce. We study such systems by molecular simulations and use the simulation\ndata to derive an effective GLE description. We find that, in an active bath,\nthe external force in the GLE is not equal to the physical external force, but\nrather a renormalized external force, which can be significantly smaller. The\neffect cannot be attributed to the mere temperature renormalization, which is\nalso observed."
    },
    {
        "anchor": "Sharp-interface approach for simulating solid-state dewetting in two\n  dimensions: a Cahn-Hoffman $\\boldsymbol\u03be$-vector formulation: By using a Cahn-Hoffman $\\boldsymbol{\\xi}$-vector formulation, we propose a\nsharp-interface approach for solving solid-state dewetting problems in two\ndimensions. First, based on the thermodynamic variation and smooth vector-field\nperturbation method, we rigorously derive a sharp-interface model with weakly\nanisotropic surface energies, and this model describes the interface evolution\nwhich occurs through surface diffusion flow and contact line migration. Second,\na parametric finite element method in terms of the $\\boldsymbol{\\xi}$-vector\nformulation is proposed for numerically solving the sharp-interface model. By\nperforming numerical simulations, we examine several specific evolution\nprocesses for solid-state dewetting of thin films, e.g., the evolution of small\nislands, pinch-off of large islands and power-law retraction dynamics of\nsemi-infinite step films, and these simulation results are highly consistent\nwith experimental observations. Finally, we also include the strong surface\nenergy anisotropy into the sharp-interface model and design its corresponding\nnumerical scheme via the $\\boldsymbol{\\xi}$-vector formulation.",
        "positive": "Electrically assisted light-induced azimuthal gliding of the nematic\n  liquid crystal easy axis on photoaligned substrates: We study azimuthal gliding of the easy axis that occurs in nematic liquid\ncrystals brought in contact with the photoaligned azo-dye film under the action\nof reorienting UV light combined with an in-plane electric field. For\nirradiation with the linearly polarized light, dynamics of easy axis\nreorientation is found to be faster as compared to the case of non-polarized\nlight. In addition, it slows down with the initial irradiation dose used to\nprepare the azo-dye film. This effect is interpreted by using the previously\nsuggested phenomenological model. We present the theoretical results computed\nby solving the torque balance equations of the model that agree very well with\nthe experimental data."
    },
    {
        "anchor": "Coordinated motion of epithelial layers on curved surfaces: Coordinated cellular movements are key processes in tissue morphogenesis.\nUsing a cell-based modeling approach we study the dynamics of epithelial layers\nlining surfaces with constant and varying curvature. We demonstrate that\nextrinsic curvature effects can explain the alignment of cell elongation with\nthe principal directions of curvature. Together with specific self-propulsion\nmechanisms and cell-cell interactions this effect gets enhanced and can explain\nobserved large-scale, persistent and circumferential rotation on cylindrical\nsurfaces. On toroidal surfaces the resulting curvature coupling is an interplay\nof intrinsic and extrinsic curvature effects. These findings unveil the role of\ncurvature and postulate its importance for tissue morphogenesis.",
        "positive": "Shear Thickening in Concentrated Soft Sphere Colloidal Suspensions: A\n  Shear Induced Phase Transition: A model of shear thickening in dense suspensions of Brownian soft sphere\ncolloidal particles is established. It suggests that shear thickening in soft\nsphere suspensions can be interpreted as a shear induced phase transition.\nBased on a Landau model of the coagulation transition of stabilized colloidal\nparticles, taking the coupling between order parameter fluctuations and the\nlocal strain-field into account, the model suggests the occurrence of clusters\nof coagulated particles (subcritical bubbles) by applying a continuous shear\nperturbation.The critical shear stress of shear thickening in soft sphere\nsuspensions is derived while reversible shear thickening and irreversible shear\nthickening have the same origin. The comparison of the theory with an\nexperimental investigation of electrically stabilized colloidal suspensions\nconfirms the presented approach."
    },
    {
        "anchor": "Theory of self-assembly of microtubules and motors: We derive a model describing spatio-temporal organization of an array of\nmicrotubules interacting via molecular motors. Starting from a stochastic model\nof inelastic polar rods with a generic anisotropic interaction kernel we obtain\na set of equations for the local rods concentration and orientation. At large\nenough mean density of rods and concentration of motors, the model describes an\norientational instability. We demonstrate that the orientational instability\nleads to the formation of vortices and (for large density and/or kernel\nanisotropy) asters seen in recent experiments. We derive the specific form of\nthe interaction kernel from the detailed analysis of microscopic interaction of\ntwo filaments mediated by a moving molecular motor, and extend our results to\ninclude variable motor density and motor attachment to the substrate.",
        "positive": "One-dimensional colloidal model with dielectric inhomogeneity: We consider a one-dimensional model allowing analytical derivation of the\neffective interactions between two charged colloids. We evaluate exactly the\npartition function for an electroneutral salt-free suspension with dielectric\njumps at the colloids' position. We derive a contact relation with the pressure\nthat shows there is like-charge attraction, whether or not the counterions are\nconfined between the colloids. In contrast to the homogeneous dielectric case,\nthere is the possibility for the colloids to attract despite the number of\ncounter-ions ($N$) being even. The results are shown to recover the mean-field\nprediction in the limit $N\\to \\infty$."
    },
    {
        "anchor": "Classical quantum friction at water-carbon interfaces: Friction at water-carbon interfaces remains a major puzzle with theories and\nsimulations unable to explain experimental trends in nanoscale waterflow. A\nrecent theoretical framework -- quantum friction (QF)-- proposes to resolve\nthese experimental observations by considering nonadiabatic coupling between\ndielectric fluctuations in water and graphitic surfaces. Here, using a\nclassical model that enables fine-tuning of the solid's dielectric spectrum, we\nprovide evidence from simulations in general support of QF. In particular, as\nfeatures in the solid's dielectric spectrum begin to overlap with water's\nlibrational and Debye modes, we find an increase in friction in line with that\nproposed by QF. At the microscopic level, we find that this contribution to\nfriction manifests more distinctly in the dynamics of the solid's charge\ndensity than that of water. Our findings suggest that experimental signatures\nof QF may be more pronounced in the solid's response rather than liquid\nwater's.",
        "positive": "Jamming modulates coalescence dynamics of shear-thickening colloidal\n  droplets: Recent investigations into coalescence dynamics of complex fluid droplets\nrevealed the existence of sub-Newtonian behaviour for polymeric fluids (elastic\nand shear thinning). We hypothesize that such delayed coalescence or\nsub-Newtonian coalescence dynamics may be extended to the general class of\nshear thickening fluids. To investigate this droplets of aqueous corn-starch\nsuspensions were chosen and its coalescence in sessile pendant configuration\nwas probed by high-speed real time imaging. Temporal evolution of the neck\n(growth) during coalescence was quantified as a function of suspended particle\nweight fraction \\phi_w. The necking behaviour was found to evolve as the\npower-law relation $R=at^b$ where R is neck radius with exponent $\\b\\le0.5$\nimplying it is a subset of the generic sub-Newtonian coalescence. Second\nsignificant delay in the coalescence dynamics is observed for particle\nfractions beyond the jamming fraction {\\ \\phi}_w>\\ \\phi_J\\geq0.35}. Our\nproposed theoretical model captures this delay implicitly through altered\nsuspension viscosity stemming from increased particle content."
    },
    {
        "anchor": "Shearing of frictional sphere packings: We measure shear response in packings of glass beads by pulling a thin,\nrough, metal plate vertically through a bed of volume fraction phi, which is\nset, before the plate is pulled, in the range 0.575 to 0.628. The yield stress\nis velocity independent over 4 decades and increases exponentially with phi,\nwith a transition at phi approximately 0.595. An analysis of the measured force\nfluctuations indicates that the shear modulus is significantly smaller than the\nbulk modulus.",
        "positive": "Tunable Thermal Switching via DNA-Based Nano Devices: DNA has a well-defined structural transition -- the denaturation of its\ndouble-stranded form into two single strands -- that strongly affects its\nthermal transport properties. We show that, according to a widely implemented\nmodel for DNA denaturation, one can engineer DNA \"heattronic\" devices that have\na rapidly increasing thermal conductance over a narrow temperature range across\nthe denaturation transition (~350 K). The origin of this rapid increase of\nconductance, or \"switching\", is the softening of the lattice and suppression of\nnonlinear effects as the temperature crosses the transition temperature and DNA\ndenatures. Most importantly, we demonstrate that DNA nanojunctions have a broad\nrange of thermal tunability due to varying the sequence and length, and\nexploiting the underlying nonlinear behavior. We discuss the role of disorder\nin the base sequence, as well as the relation to genomic DNA. These results set\nthe basis for developing thermal devices out of materials with nonlinear\nstructural dynamics, as well as understanding the underlying mechanisms of DNA\ndenaturation."
    },
    {
        "anchor": "Scaling laws for the response of nonlinear elastic media with\n  implications for cell mechanics: We show how strain stiffening affects the elastic response to internal\nforces, caused either by material defects and inhomogeneities or by active\nforces that molecular motors generate in living cells. For a spherical force\ndipole in a material with a strongly nonlinear strain energy density, strains\nchange sign with distance, indicating that even around a contractile inclusion\nor molecular motor there is radial compression; it is only at long distance\nthat one recovers the linear response in which the medium is radially\nstretched. Scaling laws with irrational exponents relate the far-field\nrenormalized strain to the near-field strain applied by the inclusion or active\nforce.",
        "positive": "Catalysis from the bottom-up: Catalysis, the acceleration of chemical reactions by molecules that are not\nconsumed in the process, is essential to living organisms but currently absent\nin physical systems that aspire to emulate biological functionalities with\nartificial components. Here we demonstrate how to design a catalyst using\nspherical building blocks interacting via programmable potentials, and show\nthat a minimal catalyst design, a rigid dimer, can accelerate a ubiquitous\nelementary reaction, the cleaving of a bond. By combining coarse-grained\nmolecular dynamics simulations and theory, and by comparing the mean reaction\ntime in the presence and absence of the catalyst, we derive geometrical and\nphysical constraints for its design and determine the reaction conditions under\nwhich catalysis emerges in the system. The framework and design rules that we\nintroduce are general and can be applied to experimental systems on a wide\nrange of scales, from micron size DNA-coated colloids to centimeter size\nmagnetic handshake materials, opening the door to the realization of\nself-regulated artificial systems with bio-inspired functionalities."
    },
    {
        "anchor": "Effective Landau theory of ferronematics: An effective Landau-like description of ferronematics, i.e., suspensions of\nmagnetic colloidal particles in a nematic liquid crystal (NLC), is developed in\nterms of the corresponding magnetization and nematic director fields. The study\nis based on a microscopic model and on classical density functional theory.\nFerronematics are susceptible to weak magnetic fields and they can exhibit a\nferromagnetic phase, which has been predicted several decades ago and which has\nrecently been found experimentally. Within the proposed effective Landau theory\nof ferronematics one has quantitative access, e.g., to the coupling between the\nmagnetization of the magnetic colloids and the nematic director of the NLC. On\nmesoscopic length scales this generates complex response patterns.",
        "positive": "Inertia drives concentration-wave turbulence in swimmer suspensions: We discover an instability mechanism in suspensions of self-propelled\nparticles that does not involve active stress. Instead, it is driven by a\nsubtle interplay of inertia, swimmer motility, and concentration fluctuations,\nthrough a crucial time lag between the velocity and the concentration field.\nThe resulting time-persistent state seen in our high-resolution numerical\nsimulations consists of self-sustained waves of concentration and orientation,\ntransiting from regular oscillations to wave turbulence. We analyze the\nstatistical features of this active turbulence, including an intriguing\nconnection to the Batchelor spectrum of passive scalars."
    },
    {
        "anchor": "Ferrofluid nucleus phase transitions in an external uniform magnetic\n  field: The phase transition between a massive dense phase and a diluted\nsuperparamagnetic phase has been studied by means of a direct molecular\ndynamics simulation. The equilibrium structures of the ferrofluid aggregate\nnucleus are obtained for different values of a temperature and an external\nmagnetic field magnitude. An approximate match of experiment and simulation has\nbeen shown for the ferrofluid phase diagram coordinates \"field-temperature\".\nThe provided phase coexistence curve has an opposite trend comparing to some of\nknown theoretical results. This contradiction has been discussed. For given\nexperimental parameters, it has been concluded that the present results\ndescribe more precisely the transition from linear chains to a dense globes\nphase. The theoretical concepts which provide the opposite binodal curve\ndependency trend match other experimental conditions: a diluted ferrofluid, a\nhigh particle coating rate, a high temperature, and/or a less particles\ncoupling constant value.",
        "positive": "Wrapping dynamics and full uptake conditions for nonspherical active\n  nanoparticles: The cellular uptake of self-propelled nanoparticles (NPs) or viruses, usually\nnonspherical, by cell membrane is crucial in many biological processes. In this\nstudy, using Onsager variational principle, we obtain a general wrapping\nequation for nonspherical self-propelled nanoparticles. Two analytical critical\nconditions are theoretically derived, one for the continuous full uptake of\nprolate particles and the other for snapthrough full wrapping of oblate\nparticles. They capture considerably well the full uptake critical boundaries\nin the phase diagrams constructed in terms of active force, aspect ratio,\nadhesion energy density, and membrane tension based on numerical calculations.\nIt is found that enhancing activity (active force), reducing effective dynamic\nviscosity, increasing adhesion energy density, and decreasing membrane tension,\ncan significantly improve the wrapping efficiency for the self-propelled\nparticles. These results elucidate some of the previous specific investigations\nconclusively and may offer novel possibilities for designing an effective\nactive NP-based vehicle for controlled drug delivery."
    },
    {
        "anchor": "Under the influence of alcohol: The effect of ethanol and methanol on\n  lipid bilayers: Extensive microscopic molecular dynamics simulations have been performed to\nstudy the effects of short-chain alcohols, methanol and ethanol, on two\ndifferent fully hydrated lipid bilayer systems in the fluid phase at 323 K. It\nis found that ethanol has a stronger effect on the structural properties of the\nmembranes. In particular, the bilayers become more fluid and permeable: Ethanol\nmolecules are able to penetrate through the membrane in typical time scales of\nabout 200 ns whereas for methanol that time scale is considerably longer, at\nleast of the order of microseconds. We find good agreement with NMR and\nmicropipette studies. We have also measured partitioning coefficients and the\nrate of crossing events for alcohols, i.e., typical time scale it takes for a\nmolecule to cross the lipid bilayer and to move from one leaflet to the other.\nFor structural properties, two-dimensional centre of mass radial-distribution\nfunctions indicate the possibility for quasi long-range order for\nethanol-ethanol correlations in contrast to liquid-like behaviour for all other\ncombinations.",
        "positive": "Active topological defect absorption by a curvature singularity: Using the Born-Oppenheimer approximation, we present a general description of\ntopological defects dynamics in $p$-atic materials on curved surfaces, and\nsimplify it in the case of active nematics. We find that activity induces a\ngeometric contribution to the motility of the $+1/2$ defect. Moreover, in the\ncase of a cone, the simplest example of a geometry with curvature singularity,\nwe find that the motility depends on the deficit angle of the cone and changes\nsign when the deficit angle is bigger than $\\pi$, leading to the change in\nactive behavior from contractile (extensile) to extensile (contractile)\nbehavior. Using our analytical framework, we then identify for positively\ncharged defects the basin of attraction to the cone apex and present\nclosed-form predictions for defect trajectories near the apex. The analytical\nresults are quantitatively corroborated against full numerical simulations.\nProvided the capture radius is small compared to the cone size, the agreement\nis excellent."
    },
    {
        "anchor": "Relation between the alpha-relaxation and the Johari-Goldstein\n  Beta-relaxation of a component in miscible blends of two glass-formers: It is well known that the \\alpha-relaxation of each component in a miscible\nmixtures of two glass-formers has its own dynamics, which change with the\ncomposition of the blend. Lesser known are the corresponding change of the\nJohari-Goldstein (JG) \\beta-relaxation and its relation to the\n\\alpha-relaxation. Previously, in neat glass-formers, the relaxation time\n\\tauJG of JG \\beta-relaxation was identified with the independent relaxation\ntime \\tau0 of the coupling model. The correspondence between \\tau0 and \\tauJG\nwas supported by analysis of experimental data of many glass-formers. In this\nwork, this correspondence between \\tau0 and \\tauJG of a component in binary\nmixtures and the relation between \\tau0 and \\tau\\alpha of the coupling model\nare used to generate predictions of the simultaneous changes of \\tau\\alpha and\n\\tau\\JG of the component on varying the composition of the mixture. The\npredictions are in accord with the experimental data of the component\n2-picoline in mixtures with either tri-styrene or ortho-terphenyl by T.\nBlochowicz and E.A. Rossler, Phys.Rev.Lett. in press(2004).",
        "positive": "Density and conformation with relaxed substrate, bulk, and interface\n  electrophoretic deposition of polymer chains: Characteristics of relaxed density profile and conformation of polymer chains\nare studied by a Monte Carlo simulation on a discrete lattice in three\ndimensions using different segmental (kink-jump $K$, crank-shaft $C$, reptation\n$R$) dynamics. Three distinct density regimes, substrate, bulk, and interface,\nare identified. With the $KC$ segmental dynamics we find that the substrate\ncoverage grows with a power-law, $d_s \\propto t^{\\gamma}$ with a field\ndependent nonuniversal exponent $\\gamma = 0.23 + 0.7 E$. The bulk volume\nfraction $d_b$ and the substrate polymer density ($d_s$) increases\nexponentially with the field ($d_b \\propto E^{0.4}$, $d_s \\propto E^{0.2}$) in\nthe low field regime. The interface polymer density $d_f$ increases with the\nmolecular weight. With the $KCR$ segmental dynamics, bulk and substrate density\ndecreases linearly with the temperature at high temperatures. The bulk volume\nfraction is found to decay with the molecular weight, $d_b \\propto\nL_c^{-0.11}$. The radius of gyration remains Gaussian in all density regions."
    },
    {
        "anchor": "Designing morphology of separated phases in multicomponent liquid\n  mixtures: Phase separation of multicomponent liquid mixtures plays an integral part in\nmany processes ranging from industry to cellular biology. In many cases the\nmorphology of coexisting phases is crucially linked to the function of the\nseparated mixture, yet it is unclear what determines morphology when multiple\nphases are present. We developed a graph theory approach to predict the\ntopology of coexisting phases from a given set of surface energies (forward\nproblem), enumerate all topologically distinct morphologies, and reverse\nengineer conditions for surface energies that produce the target morphology\n(inverse problem).",
        "positive": "Dynamics of self-propelled Janus particles in viscoelastic fluids: We experimentally investigate active motion of spherical Janus colloidal\nparticles in a viscoelastic fluid. Self-propulsion is achieved by a local\nconcentration gradient of a critical polymer mixture which is imposed by laser\nillumination. Even in the regime where the fluid's viscosity is independent\nfrom the deformation rate induced by the particle, we find a remarkable\nincrease of up to two orders of magnitude of the rotational diffusion with\nincreasing particle velocity, which can be phenomenologically described by an\neffective rotational diffusion coefficient dependent on the Weissenberg number.\nWe show that this effect gives rise to a highly anisotropic response of\nmicroswimmers in viscoelastic media to external forces depending on its\norientation."
    },
    {
        "anchor": "The Unreasonable Effectiveness of the Nallet Model: In 1993, Nallet, Laversanne and Roux put forward a simplified model for the\nintensity scattered by lamellar phases, which was nonetheless very successfully\nused in fitting experimental results, especially those obtained with powder\nsystems. I argue that the success as well as the simple expression of the model\nresult from an approximate integration over sample orientation, resulting from\nan implicit integration over the scattering vector component normal to the\ndirector.",
        "positive": "Effects of vertical confinement on gelation and sedimentation of\n  colloids: We consider the sedimentation of a colloidal gel under confinement in the\ndirection of gravity. The confinement allows us to compare directly experiments\nand computer simulations, for the same system size in the vertical direction.\nThe confinement also leads to qualitatively different behaviour compared to\nbulk systems: in large systems gelation suppresses sedimentation, but for small\nsystems sedimentation is enhanced relative to non-gelling suspensions, although\nthe rate of sedimentation is reduced when the strength of the attraction\nbetween the colloids is strong. We map interaction parameters between a model\nexperimental system (observed in real space) and computer simulations.\nRemarkably, we find that when simulating the system using Brownian dynamics in\nwhich hydrodynamic interactions between the particles are neglected, we find\nthat sedimentation occurs on the same timescale as the experiments, however the\nthickness of the \"arms\" of the gel is rather larger in the experiments,\ncompared with the simulations. An analysis of local structure in the\nsimulations showed similar behaviour to gelation in the absence of gravity."
    },
    {
        "anchor": "Swimming in circles: Motion of bacteria near solid boundaries: Near a solid boundary, E. coli swims in clockwise circular motion. We provide\na hydrodynamic model for this behavior. We show that circular trajectories are\nnatural consequences of force-free and torque-free swimming, and the\nhydrodynamic interactions with the boundary, which also leads to a hydrodynamic\ntrapping of the cells close to the surface. We compare the results of the model\nwith experimental data and obtain reasonable agreement. In particular, we show\nthat the radius of curvature of the trajectory increases with the length of the\nbacterium body.",
        "positive": "Effect of lateral confinement on the apparent mass of particle dampers: We study, via DEM simulations, the apparent mass $m$ and loss factor $\\eta$\nof particle dampers (PD) attached to a vertically driven, single degree of\nfreedom mechanical system. Although many studies focus on $\\eta$, less work has\nbeen devoted to $m$. It has been recently demonstrated [M. Masmoudi \\textit{et\nal}. Granular Matter 18 (2016) 71.] that $m$ non-linearly depends on the\ndriving acceleration $\\gamma$ according to a power law, $m\\propto\\gamma^k$.\nExperiments using 3D packings of particles suggest $k=-2$. However, simulations\nwith 1D columns of particles on a vibrating plate and theoretical predictions\nbased on the inelastic bouncing ball model (IBBM) suggest that $k=-1$. These\nfindings left open questions whether m may depend on the dimensionality of the\npacking or on lateral interactions between walls and grains. In turn, $\\eta$\nwas shown to follow a universal curve, $\\eta\\propto\\gamma^{-1}$, whatever the\ndimensionality and the constraints in the motion of the grains. In this work,\nwe consider PD under different confinement conditions in the motion of the\nparticles (1D, quasi-1D, quasi-2D and 3D). We find that the dynamical response\nof the PD ($m$ and $\\eta$) is not sensitive to the lateral confinement or\ndimensionality. However, we have observed two distinct regimes: (i) In the\ninertial regime, $\\eta$ decays according to the IBBM for all dimensions,\n$\\eta\\propto\\gamma^{-1}$, while $m$ falls with an apparent power law behaviour\nthat matches Masmoudi's experiments, $m\\propto\\gamma^{-2}$, for all dimensions\nbut only in the range of moderate acceleration, before becoming negative for\nvery high accelerations. (ii) In the quasi-static regime, both $m$ and $\\eta$\ndisplay a complex behavior as functions of the excitation amplitude, but tend\nto the IBBM prediction, $m\\propto\\gamma^{-1}$ and $\\eta\\propto\\gamma^{-1}$."
    },
    {
        "anchor": "Microemulsion nanocomposites: phase diagram, rheology and structure\n  using a combined small angle neutron scattering and reverse Monte Carlo\n  approach: The effect of silica nanoparticles on transient microemulsion networks made\nof microemulsion droplets and telechelic copolymer molecules in water is\nstudied, as a function of droplet size and concentration, amount of copolymer,\nand nanoparticle volume fraction. The phase diagram is found to be affected,\nand in particular the percolation threshold characterized by rheology is\nshifted upon addition of nanoparticles, suggesting participation of the\nparticles in the network. This leads to a peculiar reinforcement behaviour of\nsuch microemulsion nanocomposites, the silica influencing both the modulus and\nthe relaxation time. The reinforcement is modelled based on nanoparticles\nconnected to the network via droplet adsorption. Contrast-variation Small Angle\nNeutron Scattering coupled to a reverse Monte Carlo approach is used to analyse\nthe microstructure. The rather surprising intensity curves are shown to be in\ngood agreement with the adsorption of droplets on the nanoparticle surface.",
        "positive": "Thermodynamic and dynamic anomalous behavior in the TIP4P/\u03b5\n  water model: The model Tip4p/{\\epsilon} for water is tested for the presence of\nthermodynamic and dy- namic anomalies. Molecular dynamic simulations for this\nmodel were performed and we show that for this system the density versus\ntemperature at constant pressure ex- hibits a maximum. In addition we also show\nthat the diffusion coefficient versus density at constant temperature has a\nmaximum and a minimum. The anomalous behavior of the density and of the\ndiffusion coefficient obey the water hierachy. The results for the Tip4p- are\nconsistent with experiments and when compared with the Tip4p-2005 model show\nsimilar results a variety of physical properties and better performance for the\ndielectric constant."
    },
    {
        "anchor": "Effects of finite curvature on soliton dynamics in a chain of nonlinear\n  oscillators: We consider a curved chain of nonlinear oscillators and show that the\ninterplay of curvature and nonlinearity leads to a number of qualitative\neffects. In particular, the energy of nonlinear localized excitations centered\non the bending decreases when curvature increases, i.e. bending manifests\nitself as a trap for excitations. Moreover, the potential of this trap is\ndouble-well, thus leading to a symmetry breaking phenomenon: a symmetric\nstationary state may become unstable and transform into an energetically\nfavorable asymmetric stationary state. The essentials of symmetry breaking are\nexamined analytically for a simplified model. We also demonstrate a threshold\ncharacter of the scattering process, i.e. transmission, trapping, or reflection\nof the moving nonlinear excitation passing through the bending.",
        "positive": "Partially Annealed Disorder and Collapse of Like-Charged Macroions: Charged systems with partially annealed charge disorder are investigated\nusing field-theoretic and replica methods. Charge disorder is assumed to be\nconfined to macroion surfaces surrounded by a cloud of mobile neutralizing\ncounterions in an aqueous solvent. A general formalism is developed by assuming\nthat the disorder is partially annealed (with purely annealed and purely\nquenched disorder included as special cases), i.e., we assume in general that\nthe disorder undergoes a slow dynamics relative to fast-relaxing counterions\nmaking it possible thus to study the stationary-state properties of the system\nusing methods similar to those available in equilibrium statistical mechanics.\nBy focusing on the specific case of two planar surfaces of equal mean surface\ncharge and disorder variance, it is shown that partial annealing of the\nquenched disorder leads to renormalization of the mean surface charge density\nand thus a reduction of the inter-plate repulsion on the mean-field or\nweak-coupling level. In the strong-coupling limit, charge disorder induces a\nlong-range attraction resulting in a continuous disorder-driven collapse\ntransition for the two surfaces as the disorder variance exceeds a threshold\nvalue. Disorder annealing further enhances the attraction and, in the limit of\nlow screening, leads to a global attractive instability in the system."
    },
    {
        "anchor": "Hydrogen bonding exchange and supramolecular dynamics of monohydroxy\n  alcohols: This Letter unravels hydrogen bonding dynamics and their relationship with\nsupramolecular relaxations of monohydroxy alcohols (MAs) at intermediate times.\nRheological modulus of MAs exhibit Rouse scaling relaxation of G(t) ~ t^(-1/2)\nswitching to G(t) ~ t^(-1) at time tau_m before their terminal time. Meanwhile,\ndielectric spectroscopy reveals clear signatures of new supramolecular dynamics\nmatching with tau_m from rheology. Interestingly, the characteristic time,\ntau_m, follows an Arrhenius-like temperature dependence over exceptionally wide\ntemperatures and agrees well with the hydrogen bonding exchange time from\nnuclear magnetic resonance measurements. These observations demonstrate the\npresence of collective Rouse-like sub-chain motions and the active\nchain-swapping of MAs at intermediate times. Moreover, detailed theoretical\nanalyses point out explicitly that the hydrogen bonding exchange truncates the\nRouse-type supramolecular dynamics and triggers the chain-swapping processes,\nsupporting a recently proposed living polymer model.",
        "positive": "Friction and Pressure-Dependence of Force Chain Communities in Granular\n  Materials: Granular materials transmit stress via a network of force chains. Despite the\nimportance of these chains to characterizing the stress state and dynamics of\nthe system, there is no common framework for quantifying their their\nproperties. Recently, attention has turned to the tools of network science as a\npromising route to such a description. In this paper, we apply community\ndetection techniques to numerically-generated packings of spheres over a range\nof interparticle friction coefficients and confining pressures. In order to\nextract chain-like features, we use a modularity maximization with a\nrecently-developed geographical null model \\cite{Bassett2015}, and optimize the\ntechnique to detect branched structures by minimizing the normalized convex\nhull of the detected communities. We characterize the force chain communities\nby their size (number of particles), network strength (internal forces), and\nnormalized convex hull ratio (sparseness). We find the that the first two\nexhibit an approximately linear correlation and are therefore largely\nredundant. For both pressure $P$ and interparticle friction $\\mu$, we observe\ncrossovers in behavior. For $\\mu \\lesssim 0.1$, the packings exhibit more\nsensitivity to pressure. In addition, we identify a crossover pressure where\nthe frictional dependence switches from having more large/strong communities at\nlow $\\mu$ vs. high $\\mu$. We explain these phenomena by comparison to the\nspatial distribution of communities along the vertical axis of the system.\nThese results provide new tools for considering the mesoscale structure of a\ngranular system and pave the way for reduced descriptions based on the force\nchain structure."
    },
    {
        "anchor": "Sensing DNA - DNA as nanosensor: a perspective towards nanobiotechnology: Based on modern single molecule techniques, we devise a number of possible\nexperimental setups to probe local properties of DNA such as the presence of\nDNA-knots, loops or folds, or to obtain information on the DNA-sequence.\nSimilarly, DNA may be used as a local sensor. Employing single molecule\nfluorescence methods, we propose to make use of the physics of DNA denaturation\nnanoregions to find out about the solvent conditions such as ionic strength,\npresence of binding proteins, etc. By measuring dynamical quantities in\nparticular, rather sensitive nanoprobes may be constructed with contemporary\ninstruments.",
        "positive": "Ion-induced nanopatterning of a bacterial cellulose hydrogel: Hydrogels provide a solution-mimicking environment for the interaction with\nliving systems that make them desirable for various biomedical and\ntechnological applications. Because relevant biological processes in living\ntissues occur at the biomolecular scale, hydrogel nanopatterning can be\nleveraged to attain novel material properties and functionalities. However, the\nfabrication of high aspect ratio (HAR) nanostructures in hydrogels capable of\nself-standing in aqueous environments, with fine control of the size and shape\ndistribution, remains challenging. Here, we report the synthesis of\nnanostructures with a HAR in bacterial cellulose (BC) hydrogel via directed\nplasma nanosynthesis using argon ions. The nanostructures in BC are\nreproducible, stable to sterilization, and liquid immersion. Using in-situ\nsurface characterization and semi-empirical modeling, we discovered that\npattern formation was linked to the formation of graphite-like clusters\ncomposed of a mixture of C-C and C=C bonds. Moreover, our model predicts that\nreactive species at the onset of the argon irradiation accelerate the bond\nbreaking of weak bonds, contributing to the formation of an amorphous carbon\nlayer and nanopattern growth."
    },
    {
        "anchor": "Non-monotonic pressure dependence of the dynamics of soft glass-formers\n  at high compressions: In molecular dynamics simulations of soft glass-formers interacting via\nrepulsions, we find that the glass transition temperature, dynamical\nheterogeneity, and glass fragility reach their maxima at the same crossover\npressure $P_d$. Our analysis of the zero-temperature jammed states indicates\nthat states at $P_d$ have the highest bond orientational order with the largest\nspatial fluctuation. Correspondingly, the low-frequency normal modes of\nvibration are the least localized and the average potential energy barrier\nalong these modes are the highest for jammed states in the vicinity of $P_d$.\nThe reentrant glass transition and dynamics of supercooled liquids are thus\npredictable by these structural and vibrational precursors in the\nzero-temperature jammed states.",
        "positive": "Thermodynamically consistent coarse-graining of polar active fluids: We introduce a closure model for coarse-grained kinetic theories of polar\nactive fluids. Based on a quasi-equilibrium approximation of the particle\ndistribution function, the model closely captures important analytical\nproperties of the kinetic theory, including its linear stability and the\nbalance of entropy production and dissipation. Nonlinear simulations show the\nmodel reproduces the qualitative behavior and nonequilibrium statistics of the\nkinetic theory, unlike commonly used closure models. We use the closure model\nto simulate highly turbulent suspensions in both two and three dimensions in\nwhich we observe complex multiscale dynamics, including large concentration\nfluctuations and a proliferation of polar and nematic defects."
    },
    {
        "anchor": "Phasonic Diffusion and Self-confinement of Decagonal Quasicrystals in\n  Hyperspace: We introduce a novel simulation method that is designed to explore\nfluctuations of the phasonic degrees of freedom in decagonal colloidal\nquasicrystals. Specifically, we attain and characterise thermal equilibrium of\nthe phason ensemble via Monte Carlo simulations with particle motions\nrestricted to elementary phasonic flips. We find that, at any temperature, the\nrandom tiling ensemble is strongly preferred over the minimum phason-strain\nquasicrystal. Phasonic flips are the dominant carriers of diffusive mass\ntransport in physical space. Sub-diffusive transients suggest cooperative flip\nbehaviour on short time scales. In complementary space, particle mobility is\ngeometrically restricted to a thin ring around the acceptance domain, resulting\nin self-confinement and persistent phasonic order.",
        "positive": "Hydrodynamic Coupling of Particle Inclusions Embedded in Curved Lipid\n  Bilayer Membranes: We develop theory and computational methods to investigate particle\ninclusions embedded within curved lipid bilayer membranes. We consider the case\nof spherical lipid vesicles where inclusion particles are coupled through (i)\nintramembrane hydrodynamics, (ii) traction stresses with the external and\ntrapped solvent fluid, and (iii) intermonolayer slip between the two leaflets\nof the bilayer. We investigate relative to flat membranes how the membrane\ncurvature and topology augment hydrodynamic responses. We show how both the\ntranslational and rotational mobility of protein inclusions are effected by the\nmembrane curvature, ratio of intramembrane viscosity to solvent viscosity, and\ninter-monolayer slip. For general investigations of many-particle dynamics, we\nalso discuss how our approaches can be used to treat the collective diffusion\nand hydrodynamic coupling within spherical bilayers."
    },
    {
        "anchor": "Importance of Many Particle Correlations to the Collective Debye-Waller\n  Factor in a Single-Particle Activated Dynamic Theory of the Glass Transition: We theoretically study the importance of many body correlations on the\ncollective Debye Waller (DW) factor in the context of the Nonlinear Langevin\nEquation (NLE) single particle activated dynamics theory of glass transition\nand its extension to include collective elasticity (ECNLE theory). This\nmicroscopic force-based approach envisions structural alpha relaxation as a\ncoupled local-nonlocal process involving correlated local cage and longer range\ncollective barriers. The crucial question addressed here is the importance of\nthe deGennes narrowing contribution versus a literal Vineyard approximation for\nthe collective DW factor that enters the construction of the dynamic free\nenergy in NLE theory. While the Vineyard-deGennes approach-based NLE theory and\nits ECNLE theory extension yields predictions that agree well with experimental\nand simulation results, use of a literal Vineyard approximation for the\ncollective DW factor massively overpredicts the activated relaxation time. The\ncurrent study suggests many particle correlations are crucial for a reliable\ndescription of activated dynamics theory of model hard sphere fluids.",
        "positive": "Effect of impurities on transport through organic molecular films from\n  first principles: We calculate electron transport through molecular monolayers of saturated\nalkanes with point defects from first principles. Single defects (incorporated\nAu ions, kinks, dangling bonds) produce deep localized levels in the gap\nbetween occupied and unoccupied molecular levels. Single defects produce steps\non the I-V curve, whereas pairs of (unlike and like) defects give negative\ndifferential resistance peaks. The results are discussed in relation to the\nobserved unusual transport behavior of organic monolayers and compared with\ntransport through conjugated polythiophenes."
    },
    {
        "anchor": "Permanent shear localization in dense disordered materials due to\n  microscopic inertia: In this work we develop a theoretical framework for the localization of flow\nin the steadily flowing regime of sheared disordered solids with inertial\ndynamics on a microscopic scale. To this aim we perform rheology studies at\nfixed shear rate on a 3D model of dense disordered solid. Our particle based\nsimulations reveal the existence of heterogeneous shear-profiles in the\nstationary flow under homogeneous driving conditions. To rationalize this\nresult, we propose a continuum model that couples the dynamics of the local\nflow to the evolution of a kinetic temperature field. A linear stability\nanalysis of this theory predicts the minimum system size necessary for the flow\ninstability to develop. This prediction as well as the velocity profiles\nobtained from this continuum model are in good agreement with the results from\nthe particle based simulations.",
        "positive": "Curving Origami with Mechanical Frustration: We study the three-dimensional equilibrium shape of a shell formed by a\ndeployed accordion-like origami, made from an elastic sheet decorated by a\nseries of parallel creases crossed by a central longitudinal crease.\nSurprisingly, while the imprinted crease network does not exhibit a geodesic\ncurvature, the emergent structure is characterized by an effective curvature\nproduced by the deformed central fold. Moreover, both finite element analysis\nand manually made mylar origamis show a robust empirical relation between the\nimprinted crease network's dimensions and the apparent curvature. A detailed\nexamination of this geometrical relation shows the existence of three typical\nelastic deformations, which in turn induce three distinct types of\nmorphogenesis. We characterize the corresponding kinematics of crease network\ndeformations and determine their phase diagram. Taking advantage of the\nfrustration caused by the competition between crease stiffness and kinematics\nof crease network deformations, we provide a novel tool for designing curved\norigami structures constrained by strong geometrical properties."
    },
    {
        "anchor": "Mechanistic framework for reduced-order models in soft materials:\n  Application to three-dimensional granular intrusion: Soft materials often display complex behaviors that transition through\napparent solid- and fluid-like regimes. While a growing number of microscale\nsimulation methods exist for these materials, reduced-order models that\nencapsulate the global-scale physics are often desired to predict how external\nbodies interact with soft media, as occurs in diverse situations from impact\nand penetration problems to locomotion over natural terrains. This work\nproposes a systematic program to develop three-dimensional reduced-order models\nfor soft materials from a fundamental basis using continuum symmetries and\nrheological principles. In particular, we derive a reduced-order technique for\nmodeling intrusion in granular media which we term three-dimensional Resistive\nForce Theory (3D-RFT), which is capable of accurately and quickly predicting\nthe resistive stress distribution on arbitrary-shaped intruding bodies. Aided\nby a continuum description of the granular medium, a comprehensive set of\nspatial symmetry constraints, and a limited amount of reference data, we\ndevelop a self-consistent and accurate 3D-RFT. We verify the model capabilities\nin a wide range of cases and show it can be quickly recalibrated to different\nmedia and intruder surface types. The premises leading to 3D-RFT anticipate\napplication to other soft materials with strongly hyperlocalized intrusion\nbehavior.",
        "positive": "Vogel-Fulcher law of glass viscosity: A new approach: Starting with an expression, due originally to Einstein, for the shear\nviscosity \\textit{$\\eta $}(\\textit{$\\delta \\phi $}) of a liquid having a small\nfraction \\textit{$\\delta \\phi $}by volume of solid particulate matter suspended\nin it at random, we derive an effective-medium viscosity \\textit{$\\eta\n$}(\\textit{$\\phi $}) for arbitrary \\textit{$\\phi $} which is precisely of the\nVogel-Fulcher form. An essential point of the derivation is the incorporation\nof the excluded-volume effect at each turn of the iteration \\textit{$\\phi\n$}$_{n + 1 =}$\\textit{$\\phi $}$_{n}$\\textit{+$\\delta \\phi $}. The model is\nfrankly mechanical, but applicable directly to soft matter like a dense\nsuspension of microspheres in a liquid as function of the number density.\nExtension to a glass forming supercooled liquid is plausible inasmuch as the\nlatter may be modelled statistically as a mixture of rigid, solid-like regions\n(\\textit{$\\phi $}) and floppy, liquid-like regions (1-\\textit{$\\phi $}), for\n\\textit{$\\phi $} increasing monotonically with supercooling."
    },
    {
        "anchor": "Dynamic heterogeneity in polydisperse systems: A comparative study of\n  the role of local structural order parameter and particle size: In polydisperse systems, describing the structure and any structural order\nparameter (SOP) is not trivial as it varies with the number of species we use\nto describe the system, M . Depending on the degree of polydispersity, there is\nan optimum value of M = M0 where we show that the mutual information of the\nsystem increases. However, surprisingly the correlation between a recently\nproposed SOP and the dynamics is highest for M = 1. This effect increases with\npolydispersity. We find that the SOP at M = 1 is coupled with the particle\nsize, {\\sigma}, and this coupling increases with polydispersity and decreases\nwith an increase in M . Careful analysis shows that at lower polydispersity the\nSOP is a good predictor of the dynamics. However, at higher polydispersity, the\ndynamics is strongly dependent on {\\sigma}. Since the coupling between the SOP\nand {\\sigma} is higher for M = 1 thus, it appears to be a better predictor of\nthe dynamics. We also study the Vibrality an order parameter independent of\nstructural information. Compared to SOP, at high polydispersity we find\nVibrality to be a marginally better predictor of the dynamics. However, this\nhigh predictive power of Vibrality, which is not there at lower polydispersity,\nappears to be due to its stronger coupling with {\\sigma}. Thus our study\nsuggests that for systems with high polydispersity, the correlation of any\norder parameter and {\\sigma} will affect the correlation between the order\nparameter and dynamics and need not project a generic predictive power of the\norder parameter.",
        "positive": "Nonlinear mechanics of thermoreversibly associating dendrimer glasses: We model the mechanics of associating trivalent dendrimer network glasses\nwith a focus on their energy dissipation properties. Various combinations of\nsticky bond (SB) strength and kinetics are employed. The toughness\n(work-to-fracture) of these systems displays a surprising deformation-protocol\ndependence; different association parameters optimize different properties. In\nparticular, \"strong, slow\" SBs optimize strength, while \"weak, fast\" SBs\noptimize ductility via self-healing during deformation. We relate these\nobservations to breaking, reformation, and partner-switching of SBs during\ndeformation. These studies point the way to creating associating-polymer\nnetwork glasses with tailorable mechanical properties."
    },
    {
        "anchor": "Symmetrically pulsating bubbles swim in an anisotropic fluid by\n  nematodynamics: Swimming in low-Reynolds-number fluids requires the breaking of time-reversal\nsymmetry and centrosymmetry. Microswimmers, often with asymmetric shapes,\nexhibit nonreciprocal motions or exploit nonequilibrium processes to propel.\nThe role of surrounding fluids has also attracted attention because\nviscoelastic, non-Newtonian, and anisotropic properties of fluids matter in\npropulsion efficiency and navigation. Here we experimentally demonstrate that\nanisotropic fluids, nematic liquid crystals (NLC), can make a pulsating\nspherical bubble swim despite its centrosymmetric shape and time-symmetric\nmotion. The NLC breaks the centrosymmetry by a deformed nematic director field\nwith a topological defect accompanying the bubble. The nematodynamics renders\nthe nonreciprocity in the pulsation-induced fluid flow. We also report the\nspeed enhancement by confinement and the propulsion of another symmetry-broken\nbubble dressed by a bent disclination. Our experiments and theory elucidate\nanother possible mechanism of moving bodies in complex fluids by spatiotemporal\nsymmetry breaking.",
        "positive": "Structural origin of relaxation in dense colloidal suspensions: Amorphous solids relax via slow molecular rearrangement induced by thermal\nfluctuations or applied stress. Although microscopic structural signatures\npredicting these structural relaxations have long been sought, a physically\nmotivated structural measure relevant to diverse systems remains elusive. Here,\nwe introduce a structural order parameter derived from the mean-field caging\npotential experienced by the particles due to their neighbors, which reliably\npredicts the occurrence of structural relaxations. The parameter, derived from\ndensity functional theory, is a measure of susceptibility to particle\nrearrangements that can effectively identify weak or defect-like regions in\ndisordered systems. Using experiments on dense colloidal suspensions, we\ndemonstrate a causal relationship between this order parameter and the\nstructural relaxations of the amorphous solid. In quiescent suspensions,\nincreasing the density leads to stronger correlations between the structure and\ndynamics. Under applied shear, the mean structural order parameter increases\nwith increasing strain, signaling shear-induced softening, which is accompanied\nby the proliferation of plastic events. In both cases, the order parameter\nreliably identifies weak regions where the plastic rearrangements due to\nthermal fluctuation or applied shear preferentially occur. Our study paves the\nway to a structural understanding of the relaxation of a wide range of\namorphous solids, from suspensions to metallic glasses."
    },
    {
        "anchor": "Multiple memory formation in glassy landscapes: Cyclically sheared jammed packings form memories of the shear amplitude at\nwhich they were trained by falling into periodic orbits where each particle\nreturns to the identical position in subsequent cycles. While simple models\nthat treat clusters of rearranging particles as isolated two-state systems\noffer insight into this memory formation, they fail to account for the long\ntraining times and multi-period orbits observed in simulated sheared packings.\nWe show that adding interactions between rearranging clusters overcomes these\ndeficiencies. In addition, interactions allow simultaneous encoding of multiple\nmemories which would not have been possible otherwise. These memories are\ndifferent in an essential way from those found in other systems, such as\nmultiple transient memories observed in sheared suspensions, and contain\ninformation about the strength of the interactions.",
        "positive": "Stress reorganisation and response in active solids: We present a microscopic model of a disordered viscoelastic active solid,\ni.e. an active material whose long time behaviour is elastic as opposed to\nviscous. It is composed of filaments, passive crosslinks and molecular motors\npowered by stored chemical energy, e.g. actomyosin powered by ATP. Our model\nallows us to study the collective behaviour of contractile active elements and\nhow their interaction with each other and the passive elastic elements\ndetermines the macroscopic mechanical properties of the active material. As a\nresult of the (un)binding dynamics of the active elements, we find that this\nsystem provides a highly responsive material with a dynamic mechanical response\nstrongly dependent on the amount of deformation."
    },
    {
        "anchor": "Wetting, roughness and flow boundary conditions: We discuss how the wettability and roughness of a solid impacts its\nhydrodynamic properties. We see in particular that hydrophobic slippage can be\ndramatically affected by the presence of roughness. Owing to the development of\nrefined methods for setting very well-controlled micro- or nanotextures on a\nsolid, these effects are being exploited to induce novel hydrodynamic\nproperties, such as giant interfacial slip, superfluidity, mixing, and low\nhydrodynamic drag, that could not be achieved without roughness.",
        "positive": "Formation of metastable phases by spinodal decomposition: Metastable phases may be spontaneously formed from other metastable phases\nthrough nucleation. Here we demonstrate the spontaneous formation of a\nmetastable phase from an unstable equilibrium by spinodal decomposition, which\nleads to a transient coexistence of stable and metastable phases. This\nphenomenon is generic within the recently introduced scenario of the\nlandscape-inversion phase transitions, which we experimentally realize as a\nstructural transition in a colloidal crystal. This transition exhibits a rich\nrepertoire of new phase-ordering phenomena, including the coexistence of two\nequilibrium phases connected by two physically different interfaces. In\naddition, this scenario enables the control of sizes and lifetimes of\nmetastable domains. Our findings open a new setting that broadens the\nfundamental understanding of phase-ordering kinetics, and yield new prospects\nof applications in materials science."
    },
    {
        "anchor": "A Quantitative Kinetic Theory of Flocking with Three-Particle-Closure: We consider aligning self-propelled particles in two dimensions. Their motion\nis given by generalized Langevin equations and includes non-additive N-particle\ninteractions. The qualitative behavior is as for the famous Vicsek model. We\ndevelop a kinetic theory of flocking beyond mean field. In particular, we\nself-consistently take into account the full pair correlation function. We find\nexcellent quantitative agreement of the pair correlations with direct\nagent-based simulations within the disordered regime. Furthermore we use a\nclosure relation to incorporate spatial correlations of three particles. In\nthat way we achieve good quantitative agreement of the onset of flocking with\ndirect simulations. Compared to mean field theory, the flocking transition is\nshifted significantly towards lower noise because directional correlations\nfavor disorder. We compare our theory with a recently developed Landau-kinetic\ntheory.",
        "positive": "Chaining of hard disks in nematic needles: particle-based simulation of\n  colloidal interactions in liquid crystals: Colloidal particles suspended in liquid crystals can exhibit various\neffective anisotropic interactions that can be tuned and utilized in\nself-assembly processes. We simulate a two-dimensional system of hard disks\nsuspended in a solution of dense hard needles as a model system for colloids\nsuspended in a nematic lyotropic liquid crystal. The novel event-chain Monte\nCarlo technique enables us to directly measure colloidal interactions in a\nmicroscopic simulation with explicit liquid crystal particles in the dense\nnematic phase. We find a directional short-range attraction for disks along the\ndirector, which triggers chaining parallel to the director and seemingly\ncontradicts the standard liquid crystal field theory result of a quadrupolar\nattraction with a preferred ${45^{\\circ}}$ angle. Our results can be explained\nby a short-range density-dependent depletion interaction, which has been\nneglected so far. Directionality and strength of the depletion interaction are\ncaused by the weak planar anchoring of hard rods. The depletion attraction\nrobustly dominates over the quadrupolar elastic attraction if disks come close.\nSelf-assembly of many disks proceeds via intermediate chaining, which\ndemonstrates that in lyotropic liquid crystal colloids depletion interactions\nplay an important role in structure formation processes."
    },
    {
        "anchor": "Pimples reduce and dimples enhance flat dielectric surface image\n  repulsion: Near solid-liquid or liquid-liquid interfaces with dielectric contrast,\ncharged particles interact with the induced polarization charge of the\ninterface. These interactions contribute to an effective self-energy of the\nbulk ions and mediate ion-ion interactions. For flat interfaces, the\nself-energy and the mediated interaction are neatly constructed by the image\ncharge method. For other geometries, explicit results are scarce and the\nproblem must be treated via approximations or direct computation. This article\nprovides analytical results, valid to first order in perturbation theory, for\nthe self-energy of particles near a deformed near-flat interface. Explicit\nformulas are provided for the case of a sinusoidal deformation; generic\ndeformations can then be treated by superposition. In addition to results for\nthe self-energy, the surface polarization charge due to a single ion is\npresented as a quadrature. The interaction between an ion and the deformed\nsurface is modified by the change in relative distance as well as by the\ncurvature of the surface. Solid walls with a lower dielectric constant than the\nliquid repel all ions. We show here, however, that the repulsion is reduced by\nlocal convexity and enhanced by concavity; dimples are more repulsive than\npimples.",
        "positive": "Intrinsic Defect Formation in Peptide Self-Assembly: In contrast to extensively studied defects in traditional materials, we\nreport here for the first time a systematic investigation of the formation\nmechanism of intrinsic defects in self-assembled peptide nanostructures. The\nMonte Carlo simulations with our simplified dynamic hierarchical model revealed\nthat the symmetry breaking of layer bending mode at the two ends during\nmorphological transformation is responsible for intrinsic defect formation,\nwhose microscopic origin is the mismatch between layer stacking along the\nside-chain direction and layer growth along the hydrogen bond direction.\nMoreover, defect formation does not affect the chirality of the self-assembled\nstructure, which is determined by the initial steps of the peptide\nself-assembly process."
    },
    {
        "anchor": "Drying dynamics of a charged colloidal dispersion in a confined drop: We performed a thorough investigation of the drying dynamics of a charged\ncolloidal dispersion drop in a confined geometry. We developed an original\nmethodology based on Raman micro-spectroscopy to measure spatially-resolved\ncolloids concentration profiles during the drying of the drop. These\nmeasurements lead, for the first time, to estimates of the collective diffusion\ncoefficient of the dispersion over a wide range of concentration. The\ncollective diffusion coefficient is one order of magnitude higher than the\nStokes-Einstein estimate showing the importance of the electrostatic\ninteractions for the relaxation of concentration gradients. At the same time,\nwe also performed fluorescence imaging of tracers embedded within the\ndispersion during the drying of the drop, which reveals two distinct regimes.\nAt early stages, concentration gradients along the drop lead to\nbuoyancy-induced flows. Strikingly, these flows do not influence the colloidal\nconcentration gradients that generate them, as the mass transport remains\ndominated by diffusion. At longer time scales, the tracers trajectories reveal\nthe formation of a gel which dries quasi homogeneously. For such a gel, we show\nusing linear poro-elastic modeling, that the drying dynamics is still described\nby the same transport equations as for the liquid dispersion. However, the\ncollective diffusion coefficient follows a modified generalized Stokes-Einstein\nrelation, as also demonstrated in the context of unidirectional consolidation\nby Style et al. [Crust formation in drying colloidal suspensions, Style et al.,\nProc. R. Soc. A 467, 174 (2011)].",
        "positive": "Spin-glass--like aging in colloidal and granular glasses: Motivated by the mean field prediction of a Gardner phase transition between\na \"normal glass\" and a \"marginally stable glass\", we investigate the\noff-equilibrium dynamics of three-dimensional polydisperse hard spheres, used\nas a model for colloidal or granular glasses. Deep inside the glass phase, we\nfind that a sharp crossover pressure $P_{\\rm G}$ separates two distinct\ndynamical regimes. For pressure $P < P_{\\rm G}$, the glass behaves as a normal\nsolid, displaying fast dynamics that quickly equilibrates within the glass free\nenergy basin. For $P>P_{\\rm G}$, instead, the dynamics becomes strongly\nanomalous, displaying very large equilibration time scales, aging, and a\nconstantly increasing dynamical susceptibility. The crossover at $P_{\\rm G}$ is\nstrongly reminiscent of the one observed in three-dimensional spin-glasses in\nan external field, suggesting that the two systems could be in the same\nuniversality class, consistently with theoretical expectations."
    },
    {
        "anchor": "Confinement-induced shape transitions in multilamellar vesicles: Morphologies of a vesicle confined in a spherical vesicle were explored\nexperimentally by fast confocal laser microscopy and numerically by a\ndynamically-triangulated membrane model with area-difference elasticity. The\nconfinement was found to induce several novel shapes of the inner vesicles,\nthat had been never observed in unilamellar vesicles: double and quadruple\nstomatocytes, slit vesicle, and vesicles of two or three compartments with\nvarious shapes. The simulations reproduced the experimental results very well\nand some of the shape transitions can be understood by a simple theoretical\nmodel for axisymmetric shapes.",
        "positive": "Odd mechanical screening in disordered solids: Disordered solids, straddling the solid-fluid boundary, lack a comprehensive\ncontinuum mechanical description. They exhibit a complex microstructure wherein\nmultiple meta-stable states exist. Deforming disordered solids induces\nparticles rearrangements enabling the system to transition between these\nmeta-stable states. A dramatic consequence of these transitions is that\nquasistatic deformation cycles modify the reference state, facilitating the\nstorage and release of mechanical energy. Here we develop a continuum theory\nthat generalizes classical elasticity by accounting both for the absence of\nreference state, and the lack of conserved potential energy. Our theory\nincludes a new modulus describing non-conservative mechanical screening. We\nderive predictions in closed analytic form for the deformation field for\nvarious perturbations and geometries. While our theory applies to general\ndisordered solids, we focus on a two-dimensional disordered granular system and\npredict accurately the non-affine displacement fields observed in experiments\nfor both small and large deformations. The new proposed moduli satisfy\nuniversal relations that are independent of the specific experimental\nrealization. Our work thus forms the basis of an entirely new family of\ncontinuum descriptions of the mechanics of disordered solids."
    },
    {
        "anchor": "Squirmers with swirl -- a model for $Volvox$ swimming: Colonies of the green alga $Volvox$ are spheres that swim through the beating\nof pairs of flagella on their surface somatic cells. The somatic cells\nthemselves are mounted rigidly in a polymeric extracellular matrix, fixing the\norientation of the flagella so that they beat approximately in a meridional\nplane, with axis of symmetry in the swimming direction, but with a roughly 15\ndegree azimuthal offset which results in the eponymous rotation of the colonies\nabout a body-fixed axis. Experiments on colonies held stationary on a\nmicropipette show that the beating pattern takes the form of a symplectic\nmetachronal wave (Brumley et al. (2012)). Here we extend the Lighthill/Blake\naxisymmetric, Stokes-flow model of a free-swimming spherical squirmer\n(Lighthill (1952), Blake (1971b)) to include azimuthal swirl. The measured\nkinematics of the metachronal wave for 60 different colonies are used to\ncalculate the coefficients in the eigenfunction expansions and hence predict\nthe mean swimming speeds and rotation rates, proportional to the square of the\nbeating amplitude, as functions of colony radius. As a test of the squirmer\nmodel, the results are compared with measurements (Drescher et al. (2009)) of\nthe mean swimming speeds and angular velocities of a different set of 220\ncolonies, also given as functions of colony radius. The predicted variation\nwith radius is qualitatively correct, but the model underestimates both the\nmean swimming speed and the mean angular velocity unless the amplitude of the\nflagellar beat is taken to be larger than previously thought. The reasons for\nthis discrepancy are discussed.",
        "positive": "Pulsating active matter: We reveal that the mechanical pulsation of locally synchronised particles is\na generic route to propagate deformation waves. We consider a model of dense\nrepulsive particles whose activity drives periodic change in size of each\nindividual. The dynamics is inspired by biological tissues where cells consume\nfuel to sustain active deformation. We show that the competition between\nrepulsion and synchronisation triggers an instability which promotes a wealth\nof dynamical patterns, ranging from spiral waves to defect turbulence. We\nidentify the mechanisms underlying the emergence of patterns, and characterize\nthe corresponding transitions. By coarse-graining the dynamics, we propose a\nhydrodynamic description of an assembly of pulsating particles, and discuss an\nanalogy with reaction-diffusion systems."
    },
    {
        "anchor": "Anomalous Low-Frequency Dielectric Response of Clay-Water System: In this work we give the analysis of the low frequency dielectric response of\nselected kaolinitic clays at different water content ranging from dry, over\nplastic to liquid limit. For all samples investigated, depending on the\nmoisture content, the real part of the dielectric function reflects the\nabnormal behaviour within the certain frequency region where the negative\nvalues of real part of dielectric response have been observed. The anomalies\nare explained within a generalized conductivity model based on the clay-water\nelectrolyte ions free motion in pore water and their restricted motion near the\nclay particle surface. The results indicate that the dynamics of the ions in\nmoist clay is in part governed by anomalous diffusion.",
        "positive": "What happened to the gas-liquid transition in the system of dipolar hard\n  spheres?: We explore the equilibrium properties of a system composed of dipolar hard\nspheres. A new theory based on the ideas derived from the work of Debye and\nH\\\"uckel, Bjerrum, and Onsager is proposed to explain the absence of the\nanticipated critical point in this system."
    },
    {
        "anchor": "A Particulate Basis for an Immiscible Lattice-Gas Model: We show that a phenomenological hydrodynamic lattice-gas model of two-phase\nflow, developed by Rothman and Keller in 1988 and used extensively for\nnumerical simulations since then, can be derived from an underlying model of\nparticle interactions. From this result, we elucidate the nature of the\nhydrodynamic limit of the Rothman-Keller model.",
        "positive": "On the Elasticity of Polymer Model Networks Containing Finite Loops: Based upon the resistor analogy and using the ideal loop gas\napproximation(ILGA) it is shown that only pending loops reduce the modulus of\nan otherwise perfect network made of monodisperse strands and junctions of\nidentical functionality. Thus, the cycle rank of the network with pending\nstructures removed (cyclic and branched) is sufficient to characterize modulus,\nif the resistor analogy can be employed. It is further shown that it is\nimpossible to incorporate finite cycles into a polymer network such that\nindividual network strands are at equilibrium conformations while maintaining\nsimultaneously a force balance at the junctions. Therefore, the resistor\nanalogy provides only an approximation for the phantom modulus of networks\ncontaining finite loops. Improved approaches to phantom modulus can be\nconstructed from considering a force balance at the junctions, which requires\nknowledge of the distribution of cross-link fluctuations in imperfect networks.\nAssuming loops with equilibrium conformations and a force balance at all loop\njunctions, a lower bound estimate for the phantom modulus,\n$G_{\\text{ph}}\\approx\\left(\\xi-c_{\\text{f}}L_{1}\\right)kT/V$ is obtained within\nthe ILGA for end-linked model networks and in the limit of $L_{1}\\ll\\xi$. Here,\n$L_{1}$ is the number of primary (\"pending\") loops, $\\xi$ the cycle rank of the\nnetwork, $k$ the Boltzmann constant, $V$ the volume of the sample, and $T$ the\nabsolute temperature. $c_{\\text{f}}$ is a functionality dependent coefficient\nthat is $\\approx2.56$ for junction functionality $f=3$ and $\\approx3.06$ for\n$f=4$, while it converges quickly towards $\\approx4.2$ in the limit of large\n$f$. Further corrections to phantom modulus beyond finite loops are addressed\nbriefly."
    },
    {
        "anchor": "Universal Trajectories of Motile Particles Driven by Chemical Activity: Locomotion is essential for living cells. It enables bacteria and algae to\nexplore space for food, cancer to spread, and immune system to fight\ninfections.\n  Motile cells display trajectories of intriguing complexity, from regular\n(e.g. circular, helical, and so on) to irregular motions (run-tumble), the\norigin of which has remained elusive for over a century. This dynamics\nversatility is conventionally attributed to the shape asymmetry of the motile\nentity, to the suspending media, and/or to stochastic regulation. We propose\nhere a universal approach highlighting that these movements are generic,\noccurring for a large class of cells and artificial microswimmers, without the\nneed of invoking shape asymmetry nor stochasticity, but are encoded in their\ninherent nonlinear evolution.\n  We show, in particular, that for a circular and spherical particle moving in\na simple fluid, circular, helical and chaotic motions (akin to a persistent\nrandom walk) emerge naturally in different regions of parameter space. This\nestablishes the operating principles for complex trajectories manifestation of\nmotile systems, and offers a new vision with minimal ingredients. The reduced\nevolution equations based on symmetries are consistent with those derived for a\nmodel of an autophoretic particle including diffusion, emission/absorption at\nthe particle surface and hydrodynamics, and provide qualitative and\nquantitative agreement.",
        "positive": "Fermi Gases in Slowly Rotating Traps: Superfluid vs Collisional\n  Hydrodynamics: The dynamic behavior of a Fermi gas confined in a deformed trap rotating at\nlow angular velocity is investigated in the framework of hydrodynamic theory.\nThe differences exhibited by a normal gas in the collisional regime and a\nsuperfluid are discussed. Special emphasis is given to the collective\noscillations excited when the deformation of the rotating trap is suddenly\nremoved or when the rotation is suddenly stopped. The presence of vorticity in\nthe normal phase is shown to give rise to precession and beating phenomena\nwhich are absent in the superfluid phase."
    },
    {
        "anchor": "Size Scaling of Velocity Field in Granular Flows through Apertures: For vertical velocity field $v_{\\rm z} (r,z;R)$ of granular flow through an\naperture of radius $R$, we propose a size scaling form $v_{\\rm z}(r,z;R)=v_{\\rm\nz} (0,0;R)f (r/R_{\\rm r}, z/R_{\\rm z})$ in the region above the aperture. The\nlength scales $R_{\\rm r}=R- 0.5 d$ and $R_{\\rm z}=R+k_2 d$, where $k_2$ is a\nparameter to be determined and $d$ is the diameter of granule. The effective\nacceleration, which is derived from $v_{\\rm z}$, follows also a size scaling\nform $a_{\\rm eff} = v_{\\rm z}^2(0,0;R)R_{\\rm z}^{-1} \\theta (r/R_{\\rm r},\nz/R_{\\rm z})$. For granular flow under gravity $g$, there is a boundary\ncondition $a_{\\rm eff} (0,0;R)=-g$ which gives rise to $v_{\\rm z} (0,0;R)=\n\\sqrt{ \\lambda g R_{\\rm z}}$ with $\\lambda=-1/\\theta (0,0)$. Using the size\nscaling form of vertical velocity field and its boundary condition, we can\nobtain the flow rate $W =C_2 \\rho \\sqrt{g } R_{\\rm r}^{D-1} R_{\\rm z}^{1/2} $,\nwhich agrees with the Beverloo law when $R \\gg d$. The vertical velocity fields\n$v_z (r,z;R)$ in three-dimensional (3D) and two-dimensional (2D) hoppers have\nbeen simulated using the discrete element method (DEM) and GPU program.\nSimulation data confirm the size scaling form of $v_{\\rm z} (r,z;R)$ and the\n$R$-dependence of $v_{\\rm z} (0,0;R)$.",
        "positive": "Comment on \"Collective excitations of a degenerate gas at the BEC-BCS\n  crossover\": Very recent experiments have studied for the first time collective\nexcitations of an ultracold $^6$Li gas covering in particular the BEC-BCS\ncrossover domain. We point out that the results for the axial mode, through\nhydrodynamics, give direct access to the (3D) equation of state of the strongly\ninteracting gas, mostly near the unitarity limit. On the other hand the\nsurprising results found for the radial mode are actually not necessarily in\ncontradiction with the expectations from superfluid hydrodynamics."
    },
    {
        "anchor": "Domain formation in bicomponent vesicles induced by\n  composition-curvature coupling: Lipid vesicles composed of a mixture of two types of lipids are studied by\nintensive Monte-Carlo numerical simulations. The coupling between the local\ncomposition and the membrane shape is induced by two different spontaneous\ncurvatures of the components. We explore the various morphologies of these\nbiphasic vesicles coupled to the observed patterns such as nano-domains or\nlabyrinthine mesophases. The effect of the difference in curvatures, the\nsurface tension and the interaction parameter between components are thoroughly\nexplored. Our numerical results quantitatively agree with previous analytical\nresults obtained by [Gueguen et al., Eur. Phys. J. E, 2014, vol. 37, p. 76] in\nthe disordered (high temperature) phase. Numerical simulations allow us to\nexplore the full parameter space, especially close to and below the critical\ntemperature, where analytical results are not accessible. Phase diagrams are\nconstructed and domain morphologies are quantitatively studied by computing the\nstructure factor and the domain size distribution. This mechanism likely\nexplains the existence of nano-domains in cell membranes as observed by\nsuper-resolution fluorescence microscopy.",
        "positive": "A design framework for actively crosslinked filament networks: Living matter moves, deforms, and organizes itself. In cells this is made\npossible by networks of polymer filaments and crosslinking molecules that\nconnect filaments to each other and that act as motors to do mechanical work on\nthe network. For the case of highly cross-linked filament networks, we discuss\nhow the material properties of assemblies emerge from the forces exerted by\nmicroscopic agents. First, we introduce a phenomenological model that\ncharacterizes the forces that crosslink populations exert between filaments.\nSecond, we derive a theory that predicts the material properties of highly\ncrosslinked filament networks, given the crosslinks present. Third, we discuss\nwhich properties of crosslinks set the material properties and behavior of\nhighly crosslinked cytoskeletal networks. The work presented here, will enable\nthe better understanding of cytoskeletal mechanics and its molecular\nunderpinnings. This theory is also a first step towards a theory of how\nmolecular perturbations impact cytoskeletal organization, and provides a\nframework for designing cytoskeletal networks with desirable properties in the\nlab."
    },
    {
        "anchor": "The characterization of wettability of substrates by liquid nanodrops: Wettability of a substrates is characterized by a contact angle.\nApplicability of the simple formula developed by Derjaguin, which relates to\nthe contact angle and disjoining pressure to nano-scale liquid droplets is\nreconsidered within the framework of the theory of the first-order wetting\ntransition of volatile liquids. It is concluded that his formula is generally\ncorrect for large droplets on an incompletely-wettable substrate. But it can\nnot be applied to nanodroplets, in particular, on a completely-wettable\nsubstrate. An effective contact angle can be defined even for the nanaodroplet.\nA formula similar to the Derjaguin formula is proposed by which we can\ncalculate the contact angle of nanodorplets on both an incompletely- and a\ncompletely-wettable substrate for which the whole volume of the droplet is\nunder the influence of the disjoining pressure.",
        "positive": "Limits of isotropic plastic deformation of Bangkok clay: A model assuming incremental plastic isotropic response has been recently\nproposed to model the deformation of isotropic packing of grains, in the\nsmall-strain range. It is used here on over-consolidated remould clay, to\ninterpret the small-strain range behaviour obtained in [1,2] on Bangkok clay.\nThe data published in [1,2] at constant volume are also used here to measure\nthe size of the domain of validity in the (q/(M'p), p/po) plane, where po is\nthe over-consolidation isotropic pressure, p is the mean stress and q the\ndeviatoric stress, q . So, it is shown that the model works also for clay. This\nenlarges the application domain of model [3,4] to soft clay with OCR larger\nthan 1.2 to 1.5. Pacs # : 45.70.-n ; 62.20.Fe ; 83.80.Fg, 83.80.Hj"
    },
    {
        "anchor": "Instability of nanometric fluid films on a thermally conductive\n  substrate: We consider thin fluid films placed on thermally conductive substrates and\nexposed to time-dependent spatially uniform heat source. The evolution of the\nfilms is considered within the long-wave framework in the regime such that both\nfluid/substrate interaction, modeled via disjoining pressure, and Marangoni\nforces, are relevant. We analyze the problem by the means of linear stability\nanalysis as well as by time-dependent nonlinear simulations. The main finding\nis that when self-consistent computation of the temperature field is performed,\na complex interplay of different instability mechanisms results. This includes\neither monotonous or oscillatory dynamics of the free surface. In particular,\nwe find that the oscillatory behavior is absent if the film temperature is\nassumed to be slaved to the current value of the film thickness. The results\nare discussed within the context of liquid metal films, but are of relevance to\ndynamics of any thin film involving variable temperature of the free surface,\nsuch that the temperature and the film interface itself evolve on comparable\ntime scales.",
        "positive": "Measurements of Particle Dynamics in Slow, Dense Granular Couette Flow: Experimental measurements of particle dynamics on the lower surface of a 3D\nCouette cell containing monodisperse spheres are reported. The average radial\ndensity and velocity profiles are similar to those previously measured within\nthe bulk and on the lower surface of the 3D cell filled with mustard seeds.\nObservations of the evolution of particle velocities over time reveal distinct\nmotion events, intervals where previously stationary particles move for a short\nduration before jamming again. The cross-correlation between the velocities of\ntwo particles at a given distance $r$ from the moving wall reveals a\ncharacteristic lengthscale over which the particles are correlated. The\nautocorrelation of a single particle's velocity reveals a characteristic\ntimescale $\\tau$ which decreases with distance from the inner moving wall. This\nmay be attributed to the increasing rarity at which the discrete motion events\noccur and the reduced duration of those events at large $r$. The relationship\nbetween the RMS azimuthal velocity fluctuations, $\\delta v_\\theta(r)$, and\naverage shear rate, $\\dot\\gamma(r)$, was found to be $\\delta v_\\theta \\propto\n\\dot\\gamma^\\alpha$ with $\\alpha = 0.52 \\pm 0.04$. These observations are\ncompared with other recent experiments and with the modified hydrodynamic model\nrecently introduced by Bocquet et al."
    },
    {
        "anchor": "Structural and dynamical properties of gel networks: The competition of depletion attractions and longer-ranged repulsions between\ncolloidal particles in colloid-polymer mixtures leads to the formation of\nheterogeneous gel-like structures. For instance, gel networks, i.e., states\nwhere the colloids arrange in thin strands that span the whole system occur at\nlow packing fractions for attractions that are stronger than those at the\nbinodal line of equilibrium liquid-fluid phase separation. By using Brownian\ndynamics simulations we explore the formation, structure, and ageing dynamics\nof gel networks. We determine reduced network that focus on the essential\nconnections in a gel network. We compare the observed properties to those of\nbulky gels or cluster fluids. Our results demonstrate that both the structure\nas well as the (often slow) dynamics of the stable or meta-stable heterogenous\nstates in colloid-polymer mixtures possess distinct features on various length\nand time scales and thus are richly divers.",
        "positive": "Inhibited pattern formation by asymmetrical high voltage excitation in\n  nematic fluids: In contrast to the predictions of the standard theory of electroconvection\n(EC), our experiments showed that the action of superposed ac and dc voltages\nrather inhibits pattern formation than favours the emergence of instabilities;\nthe patternless region may extend to much higher voltages than the individual\nac or dc thresholds. The pattern formation induced by such asymmetrical voltage\nwas explored in a nematic liquid crystal in a wide frequency range. The\nfindings could be qualitatively explained for the conductive EC, but represent\na challenging problem for the dielectric EC."
    },
    {
        "anchor": "Pressure dependence of solvation of non-polar solute in simple model of\n  water: We modelled the aqueous solvation of a nonpolar solute as a function of the\nradius, temperature and pressure. In this study a simple two-dimensional\nMercedes-Benz (MB) water model was used in NPT Monte Carlo simulations. This\nmodel has previously been shown to qualitatively predict the volume anomalies\nof pure water and the free energy, enthalpy, entropy, heat capacity, and volume\nchange in order to insert a nonpolar solute into water. Here, we extended the\nstudies of solvation of nonpolar solute to examine the pressure dependence and\nbroader range of temperature and size dependence. The model shows two different\nmechanisms, one for the solvation of large nonpolar solutes bigger than water\nand the second for smaller solutes.",
        "positive": "Droplet-Induced Budding Transitions of Membranes: Motivated by recent experiments on biomimetic membranes exposed to several\naqueous phases, we theoretically study the morphology of a membrane in contact\nwith a liquid droplet formed via aqueous phase separation. We concentrate on\nmembranes with negligible spontaneous curvature. At small droplet volume,\nbending energy dominates and the droplet is only partially wrapped by the\nmembrane. At large volume, this configuration can become unstable and undergo a\ndiscontinuous transition to a state, in which the droplet is (almost)\ncompletely wrapped by the membrane. A morphology diagram, showing the parameter\nregion where such budding transition occurs, is constructed as a function of\nthe membrane tension and the intrinsic contact angle of the liquid with the\nmembrane. The effects of spontaneous curvature are discussed qualitatively."
    },
    {
        "anchor": "Emergence of solid-like Debye scaling in the vibrational density of\n  states of liquids under nanoconfinement: At frequencies higher than the inverse of the structural relaxation time\n$\\tau$, the dynamics of liquids display several solid-like properties,\nincluding propagating collective shear waves and emergent elasticity. However,\nin classical bulk liquids, where $\\tau$ is typically of the order of 1 ps or\nless, this solid-like behavior remains elusive in the low-frequency region of\nthe vibrational density of states (VDOS). Here, we provide compelling evidence\nfor the emergent solid-like nature of liquids at short distances through\ninelastic neutron scattering measurements of the low-frequency VDOS in liquid\nwater and glycerol confined within graphene oxide membranes. In particular,\nupon increasing the strength of confinement, we observe a transition from a\nliquid-like VDOS (linear in the frequency $\\omega$) to a solid-like behavior\n(Debye law, $\\sim\\omega^2$) in the range of $1$-$4$ meV. Molecular dynamics\nsimulations confirm these findings and reveal additional solid-like features,\nincluding propagating collective shear waves and a reduction in the\nself-diffusion constant. Finally, we show that the onset of solid-like dynamics\nis pushed towards low frequency along with the slowing-down of the relaxation\nprocesses upon confinement, and that the scale at which solidity emerges is\nqualitatively compatible with k-gap theory and the concept of gapped momentum\nstates. Our results provide convincing experimental evidence of the continuity\nbetween liquids and solids, as originally advocated by Frenkel and Maxwell, and\na deeper understanding of the dynamics of liquids across a wide range of length\nscales.",
        "positive": "Diethyl Sulfoxide as a Novel Neutral Ligand in the Platinum Complex\n  Anion: Diethyl sulfoxide (DESO) is far less known than its shorter-alkyl-chain\nhomolog, dimethyl sulfoxide. Although the field of senior dialkyl sulfoxides\ndoes not currently exhibit an explosive growth, new fundamental and applied\nresearch works routinely appear from a few research groups in the world.\nRecently, the tetraethylammonium diethylsulfoxidopentachloroplatinate complex\ncompound was synthesized containing the DESO molecule as a neutral ligand. In\nthe present paper, we use a systematic computational method to rationalize the\nmentioned synthetic achievement in coordination chemistry. We show that only up\nto two DESO molecules may exist in the platinum (IV) complex ion, whereas all\nhigher contents of DESO are thermodynamically unstable and the sterical factor\nplays an important role in their instabilities. Structural analysis of the\ntetraethylammonium diethylsulfoxidopentachloroplatinate ion pair reveals its\nrather strong cation-anion coordination and for the first time explains an\nexperimentally derived high melting point. The reported results are expected to\ninspire experimental efforts to extend the universe of senior sulfoxides as\nneutral organic ligands in d-metal complexes."
    },
    {
        "anchor": "Water between membranes: Structure and Dynamics: An accurate description of the structure and dynamics of interfacial water is\nessential for phospholipid membranes, since it determines their function and\ntheir interaction with other molecules. Here we consider water confined in\nstacked membranes with hydration from poor to complete, as observed in a number\nof biological systems. Experiments show that the dynamics of water slows down\ndramatically when the hydration level is reduced. All-atom molecular dynamics\nsimulations identify three (inner, hydration and outer) regions, within a\ndistance of approximately 1 nm from the membrane, where water molecules exhibit\ndifferent degrees of slowing down in the dynamics. The slow-down is a\nconsequence of the robustness of the hydrogen bonds between water and lipids\nand the long lifetime of the hydrogen bonds between water molecules near the\nmembrane. The interaction with the interface, therefore, induces a structural\nchange in the water that can be emphasized by calculating its intermediate\nrange order. Surprisingly, at distances as far as ~ 2.5 nm from the interface,\nalthough the bulk-like dynamics is recovered, the intermediate range order of\nwater is still slightly higher than that in the bulk at the same thermodynamic\nconditions. Therefore, the water-membrane interface has a structural effect at\nambient conditions that propagates further than the often-invoked 1 nm length\nscale. Membrane fluctuations smear out this effect macroscopically, but an\nanalysis performed by considering local distances and instantaneous\nconfigurations is able to reveal it, possibly contributing to our understanding\nof the role of water at biomembrane interfaces.",
        "positive": "Laser Transmission Studies with Magnetic Nanofluids: Transmission of He-Ne (632 nm, 10 mW) Gaussian laser beam through Hexane and\nWater based magnetic nanofluids containing Fe3O4 nanoparticles show strong\nnon-linear and magneto-optical effects. Application of external magnetic field\n(up to 1.7 Wb/m2) perpendicular to the incident laser beam produces a change in\nforward scattered pattern of the incident laser beam. Dependence of forward\nscattered patterns in presence of external magnetic field has been studied.\nImage processing has been carried out to understand spatial distribution of the\nforward scattered patterns and temporal evolution of patterns involving\nparticle image velocimetry technique. Change in non-linear refractive index is\nestimated for samples showing self-diffraction arising from higher order\nnon-linear optical effect. Observed effects are useful for understanding light\nscattering from magnetic nanofluids and developing optofluidic devices and\nsensors."
    },
    {
        "anchor": "Reducing model complexity by means of the Optimal Scaling: Population\n  Balance Model for latex particles morphology formation: Rational computer-aided design of multiphase polymer materials is vital for\nrapid progress in many important applications, such as: diagnostic tests, drug\ndelivery, coatings, additives for constructing materials, cosmetics, etc.\nSeveral property predictive models, including the prospective Population\nBalance Model for Latex Particles Morphology Formation (LPMF PBM), have already\nbeen developed for such materials. However, they lack computational efficiency,\nand the accurate prediction of materials' properties still remains a great\nchallenge. To enhance performance of the LPMF PBM, we explore the feasibility\nof reducing its complexity through disregard of the aggregation terms of the\nmodel. The introduced nondimensionalization approach, which we call Optimal\nScaling with Constraints, suggests a quantitative criterion for locating\nregions of slow and fast aggregation and helps to derive a family of\ndimensionless LPMF PBM of reduced complexity. The mathematical analysis of this\nnew family is also provided. When compared with the original LPMF PBM, the\nresulting models demonstrate several orders of magnitude better computational\nefficiency.",
        "positive": "Polymer-Enforced Crystallization of a Eutectic Binary Hard Sphere\n  Mixture: We prepared a buoyancy matched binary mixture of polydisperse polystyrene\nmicrogel spheres of size ratio 0.785 and at a volume fraction of 0.567 just\nbelow the kinetic glass transition. In line with theoretical expectations, a\neutectic phase behavior was observed, but only a minor fraction of the samples\ncrystallized at all. By adding a short non-adsorbing polymer we enforce\ninter-species fractionation into coexisting pure component crystals, which in\nturn also shows signs of intra-species fractionation. We show that in formerly\ninaccessible regions of the phase diagram binary hard sphere physics is made\nobservable using attractive hard spheres.\n  Ancillary files: Correction to Soft Matter 2012, 8, 627"
    },
    {
        "anchor": "Trapping, gliding, vaulting: Transport of semiflexible polymers in\n  periodic post arrays: The transport of deformable particles through porous media underlies a wealth\nof applications ranging from filtration to oil recovery to the transport and\nspreading of biological agents. Using direct numerical simulations, we analyze\nthe dynamics of semiflexible polymers under the influence of an imposed flow in\na structured two-dimensional lattice serving as an idealization of a porous\nmedium. This problem has received much attention in the limit of reptation and\nfor long-chain polymer molecules such as DNA that are transported through\nmicropost arrays for electrophoretic chromatographic separation. In contrast to\nlong entropic molecules, the dynamics of elastic polymers results from a\ncombination of scattering with the obstacles and flow-induced buckling\ninstabilities. We identify three dominant modes of transport that involve\ntrapping, gliding and vaulting of the polymers around the obstacles, and we\nreveal their essential features using tools from dynamical systems theory. The\ninterplay of these scattering dynamics with transport and deformations in the\nimposed flow results in the long-time asymptotic dispersion of the center of\nmass, which we quantify in terms of a hydrodynamic dispersion tensor. We then\ndiscuss a simple yet efficient chromatographic device that exploits the\ncompetition between different modes of transport to sort filaments in a dilute\nsuspension according to their lengths.",
        "positive": "Dressed Active Particles in Spherical Crystals: We investigate the dynamics of an active particle in two-dimensional\nspherical crystals, which provide an ideal environment to illustrate the\ninterplay of active particle and crystallographic defects. A moving active\nparticle is observed to be surrounded by localized topological defects,\nbecoming a dressed active particle. Such a physical picture characterizes both\nthe lattice distortion around the moving particle and the healing of the\ndistorted lattice in its trajectory. We find that the dynamical behaviors of an\nactive particle in both random and ballistic motions uniformly conform to this\nfeatured scenario, whether the particle is initially a defect or not. We\nfurther observe that the defect pattern around a dressed ballistic active\nparticle randomly oscillates between two well-defined wing-like defect motifs\nregardless of its speed. The established physical picture of dressed active\nparticles in this work partially deciphers the complexity of the intriguing\nnonequilibrium behaviors in active crystals, and opens the promising\npossibility of introducing the activity to engineer defects, which has strong\nconnections with the design of materials."
    },
    {
        "anchor": "Effects of the size and concentration of depleting agents on the\n  stabilization of the double-helix structure and DNA condensation: a single\n  molecule force spectroscopy study: We perform a single molecule force spectroscopy study to characterize the\nrole of the size (molecular weight) and concentration of depleting agents on\nDNA condensation and on the stabilization of the double-helix structure,\nshowing that important features such as the threshold concentration for DNA\ncondensation, the force in which the melting plateau occurs and its average\nlength strongly depend on the depletant size chosen. Such results are\npotentially important to understand how the presence of surrounding\nmacromolecules influences DNA stabilization inside living cells and therefore\nadvance in the understanding of the crowded cell environment on DNA-related\nfunctions.",
        "positive": "How Tuning Interfaces Impacts the Dynamics and Structure of Polymer\n  Nanocomposites Simultaneously: Fundamental understanding of macroscopic properties of polymer nanocomposites\n(PNCs) remains difficult due to the complex interplay of microscopic dynamics\nand structure, namely interfacial layer relaxations and three-dimensional\nnanoparticle arrangements. The effect of surface modification by alkyl\nmethoxysilanes at different grafting densities has been studied in PNCs made of\npoly(2-vinylpyridine) and spherical 20 nm silica nanoparticles (NPs). The\nsegmental dynamics has been probed by broadband dielectric spectroscopy, and\nthe filler structure by small-angle X-ray scattering and reverse Monte Carlo\nsimulations. By combining the particle configurations with the interfacial\nlayer properties, it is shown how surface modification tunes the attractive\npolymer-particle interactions: bare NPs slow down the polymer interfacial layer\ndynamics over a thickness of ca. 5 nm, while grafting screens these\ninteractions. Our analysis of interparticle spacing and segmental dynamics\nprovides unprecedented insight into the effect of surface modification on the\nmain characteristics of PNCs: particle interactions and polymer interfacial\nlayers."
    },
    {
        "anchor": "Crossover from one to three dimensions for a gas of hard-core bosons: We develop a variational theory of the crossover from the one-dimensional\n(1D) regime to the 3D regime for ultra-cold Bose gases in thin waveguides.\nWithin the 1D regime we map out the parameter space for fermionization, which\nmay span the full 1D regime for suitable transverse confinement.",
        "positive": "Dynamic properties of quasi-confined colloidal hard-sphere liquids near\n  the glass transition: The complex behavior of confined fluids arising due to a competition between\nlayering and local packing can be disentangled by considering quasi-confined\nliquids, where periodic boundary conditions along the confining direction\nrestore translational invariance. This system provides a means to investigate\nthe interplay of the relevant length scales of the confinement and the local\norder. We provide a mode-coupling theory of the glass transition (MCT) for\nquasi-confined liquids and elaborate an efficient method for the numerical\nimplementation. The nonergodicity parameters in MCT are compared to\ncomputer-simulation results for a hard-sphere fluid. We evaluate the\nnonequilibrium-state diagram and investigate the collective intermediate\nscattering function. For both methods, nonmonotonic behavior depending on the\nconfinement length is observed."
    },
    {
        "anchor": "Anomalous diffusion of self-align active particle in flow background: Active particles (i.e., self-propelled particles or called microswimmers),\ndifferent from passive Brownian particles, possess more complicated\ntranslational and angular dynamics, which can generate a series of anomalous\ntransport phenomena. In this letter, we study the two-dimensional dynamics of a\nself-propelled pointlike particle with self-aligning property moving in\nPoiseuille flow. The results show the effective anomalous diffusion coefficient\nchanges sharply with the change of temperature and speed of background\nPoiseuille flow. The relaxation property of moving speed and the position\nprobability distribution function of particles is also obtained. The\nobservation of several types of anomalous diffusion and normal diffusion regime\nindicates the self-aligning property may be universal and can be used as a\nreference for future experiments analysis and modeling.",
        "positive": "Softening of edges of solids by surface tension: Surface tension tends to minimize the area of interfaces between pieces of\nmatter in different thermodynamic phases, be they in the solid or the liquid\nstate. This can be relevant for the macroscopic shape of very soft solids, and\nlead to a roughening of initially sharp edges. We calculate this effect for a\nneo-Hookean elastic solid, with assumptions corresponding to actual\nexperiments, namely the case where an initially sharp edge is rounded by the\neffect of surface tension felt when the fluid surrounding the soft solid (and\nso surface tension) is changed at the solid/liquid boundary. We consider two\nopposite limits where the analysis can be carried to the end, the one of a\nshallow angle and the one of a very sharp angle. Both cases yield a\ndiscontinuity of curvature in the state with surface tension although the\ninitial state had a discontinuous slope."
    },
    {
        "anchor": "Optical forces arising from phase gradients: We demonstrate both theoretically and experimentally that gradients in the\nphase of a light field exert forces on illuminated objects, including forces\ntransverse to the direction of propagation. This effect generalizes the notion\nof the photon orbital angular momentum carried by helical beams of light. We\nfurther demonstrate that these forces generally violate conservation of energy,\nand briefly discuss some ramifications of their non-conservativity.",
        "positive": "Revealing the Link between Structural Relaxation and Dynamic\n  Heterogeneity in Glass-Forming Liquids: Despite the use of glasses for thousands of years, the nature of the glass\ntransition is still mysterious. On approaching the glass transition, the growth\nof dynamic heterogeneity has long been thought to play a key role in explaining\nthe abrupt slowdown of structural relaxation. However, it still remains elusive\nwhether there is an underlying link between structural relaxation and dynamic\nheterogeneity. Here we unravel the link by introducing a characteristic time\nscale hiding behind an identical dynamic heterogeneity for various model\nglass-forming liquids. We find that the time scale corresponds to the kinetic\nfragility of liquids. Moreover, it leads to scaling collapse of both the\nstructural relaxation time and dynamic heterogeneity for all liquids studied,\ntogether with a characteristic temperature associated with the same dynamic\nheterogeneity. Our findings imply that studying the glass transition from the\nviewpoint of dynamic heterogeneity is more informative than expected."
    },
    {
        "anchor": "Implications of Realistic Fracture Criteria on Crack Morphology: We study the effects realistic fracture criteria have on crack morphology\nobtained in numerical simulations with a stochastic discrete element method.\nResults are obtained with two criteria which are consistent with the theory of\nelasticity and compared with previous results using the original criterion,\nchosen when the method was first published, The conventional choice has been to\nconsider the combined loading as an interaction between bending and tensile\nforces only, leaving out shear forces altogether. Moreover the combination of\nbending and tension used in the old criterion is correct only for plastic\ndeformations. Our results show that the inclusion of shear forces have a\nprofound effect on crack morphology. We consider two types of external loading,\ntorsion applied to a circular cylinder and tension applied to a cube. In the\ntensile case, the exponent which characterises scaling of crack roughness with\nsystem size is found to be very close to the experimental value zeta = 0:5 when\nrealistic fracture criteria are used. In the present calculations we obtain\nzeta = 0.52, a value which remains constant for all disorders. It is proposed\nthat the small-scale exponent zeta = 0.8 appears as a consequence of cleavage\nbetween crystal planes and consequently requires a different fracture criterion\nthan that which is used on larger scales.",
        "positive": "Relaxation dynamics of a protein solution investigated by dielectric\n  spectroscopy: In the present work, we provide a dielectric study on two differently\nconcentrated aqueous lysozyme solutions in the frequency range from 1 MHz to 40\nGHz and for temperatures from 275 to 330 K. We analyze the three dispersion\nregions, commonly found in protein solutions, usually termed beta-, gamma-, and\ndelta-relaxation. The beta-relaxation, occurring in the frequency range around\n10 MHz and the gamma-relaxation around 20 GHz (at room temperature) can be\nattributed to the rotation of the polar protein molecules in their aqueous\nmedium and the reorientational motion of the free water molecules,\nrespectively. The nature of the delta-relaxation, which often is ascribed to\nthe motion of bound water molecules, is not yet fully understood. Here we\nprovide data on the temperature dependence of the relaxation times and\nrelaxation strengths of all three detected processes and on the dc conductivity\narising from ionic charge transport. The temperature dependences of the beta-\nand gamma-relaxations are closely correlated. We found a significant\ntemperature dependence of the dipole moment of the protein, indicating\nconformational changes. Moreover we find a breakdown of the\nDebye-Stokes-Einstein relation in this protein solution, i.e., the dc\nconductivity is not completely governed by the mobility of the solvent\nmolecules. Instead it seems that the dc conductivity is closely connected to\nthe hydration shell dynamics."
    },
    {
        "anchor": "Calculation of absolute free energy of binding for theophylline and its\n  analogs to RNA aptamer using nonequilibrium work values: The massively parallel computation of absolute binding free energy with a\nwell-equilibrated system (MP-CAFEE) has been developed [H. Fujitani, Y. Tanida,\nM. Ito, G. Jayachandran, C. D. Snow, M. R. Shirts, E. J. Sorin, and V. S.\nPande, J. Chem. Phys. ${\\bf 123}$, 084108 (2005)]. As an application, we\nperform the binding affinity calculations of six theophylline-related ligands\nwith RNA aptamer. Basically, our method is applicable when using many compute\nnodes to accelerate simulations, thus a parallel computing system is also\ndeveloped. To further reduce the computational cost, the adequate non-uniform\nintervals of coupling constant $\\lambda$, connecting two equilibrium states,\nnamely bound and unbound, are determined. The absolute binding energies $\\Delta\nG$ thus obtained have effective linear relation between the computed and\nexperimental values. If the results of two other different methods are\ncompared, thermodynamic integration (TI) and molecular mechanics\nPoisson-Boltzmann surface area (MM-PBSA) by the paper of Gouda $et al$ [H.\nGouda, I. D. Kuntz, D. A. Case, and P. A. Kollman, Biopolymers ${\\bf 68}$, 16\n(2003)], the predictive accuracy of the relative values $\\Delta\\Delta G$ is\nalmost comparable to that of TI: the correlation coefficients (R) obtained are\n0.99 (this work), 0.97 (TI), and 0.78 (MM-PBSA). On absolute binding energies\nmeanwhile, a constant energy shift of $\\sim$ -7 kcal/mol against the\nexperimental values is evident. To solve this problem, several presumable\nreasons are investigated.",
        "positive": "Effect of Chain Flexibility on Nematic-Smectic Transition: The theory of nematic-smectic phase transition in the system of uniform\nsemi-flexible chains with hard-core repulsion is presented. Both the general\ndensity-functional formalism the tube-model calculation show that the\nflexibility of the chains results in a strong first-order transition, in\ncontrast to the common weak-cristallization scenario of the nematic-smectic\ntransition in rigid rods. The calculated spinodal volume fraction of the\nuniform nematic phase and the period of the modulation instability are\nconsistent with recent experimental results."
    },
    {
        "anchor": "Confinement free energy of flexible polyelectrolytes in spherical\n  cavities: A weakly charged flexible polyelectrolyte chain in a neutral spherical cavity\nis analyzed using self-consistent field theory (SCFT) within an explicit\nsolvent model. Assuming the radial symmetry for the system, it is found that\nthe confinement of the chain leads to creation of a charge density wave along\nwith the development of a potential difference across the center of cavity and\nthe surface. We show that the solvent entropy plays an important role in the\nfree energy of the confined system. For a given radius of the spherical cavity\nand fixed charge density along the backbone of the chain, solvent and small ion\nentropies dominate over all other contributions when chain lengths are small.\nHowever, with the increase in chain length, chain conformational entropy and\npolymer-solvent interaction energy also become important. Our calculations\nreveal that energy due to electrostatic interactions plays a minor role in the\nfree energy. Furthermore, we show that the total free energy under spherical\nconfinement is not extensive in the number of monomers. Results for the osmotic\npressure and mean activity coefficient for monovalent salt are presented. We\ndemonstrate that fluctuations at one-loop level lower the free energy and\ncorrections to the osmotic pressure and mean activity coefficient of the salt\nare discussed. Finite size corrections are shown to widen the range of validity\nof the fluctuation analysis.",
        "positive": "Sign switch of Gaussian bending modulus for microemulsions; a\n  self-consistent field analysis exploring scale invariant curvature energies: Bending rigidities of tensionless balanced liquid-liquid interfaces as\noccurring in microemulsions are predicted using self-consistent field theory\nfor molecularly inhomogeneous systems. Considering geometries with scale\ninvariant curvature energies gives unambiguous bending rigidities for systems\nwith fixed chemical potentials: The minimal surface Im3m cubic phase is used to\nfind the Gaussian bending rigidity, $\\bar{\\kappa}$, and a torus with Willmore\nenergy $W=2 \\pi^2$ allows for direct evaluation of the mean bending modulus,\n$\\kappa$. Consistent with this, the spherical droplet gives access to $2 \\kappa\n+ \\bar{\\kappa}$. We observe that $\\bar{\\kappa}$ tends to be negative for strong\nsegregation and positive for weak segregation; a finding which is instrumental\nfor understanding phase transitions from a lamellar to a sponge-like\nmicroemulsion. Invariably, $\\kappa$ remains positive and increases with\nincreasing strength of segregation."
    },
    {
        "anchor": "Fundamental inequalities in the Stoner-Wohlfarth model: We report two fundamental inequalities in the Stoner-Wohlfarth model.\nSpecifically, we investigate the theoretical limit for the initial magnetic\nsusceptibility in a system described by the Stoner-Wohlfarth approach. We also\nfind analytical solutions for the magnetization in the low-field regime and\nobtain the borderline value for the uniaxial anisotropy constant in such an\nideal Stoner-Wohlfarth system. We go beyond and introduce a general mean-field\ntheory for interacting Stoner-Wohlfarth-like systems, thus estimating how the\ninitial magnetic susceptibility is affected by the dipolar and exchange\ninteractions inside the system. By means of a simple insight from a fundamental\ninequality for the magnetic susceptibility of an ideal Stoner-Wohlfarth system,\nwe show its violation is a signature of the existence of exchange interactions\nbetween nanoparticles in an interacting Stoner-Wohlfarth-like system.",
        "positive": "Order-disorder transition in swirled granular disks: We study the order-disorder transition of horizontally swirled dry and wet\ngranular disks by means of computer simulations. Our systematic investigation\nof the local order formation as a function of amplitude and period of the\nexternal driving force shows that a large cluster of hexagonally ordered\nparticles forms for both dry and wet granular particles at intermediate driving\nenergies. Disordered states are found at small and large driving energies. Wet\ngranular particles reach a higher degree of local hexagonal order, with respect\nto the dry case. For both cases we report a qualitative phase diagram showing\nthe amount of local order at different state points. Furthermore we find that\nthe transition from hexagonal order to a disordered state is characterised by\nthe appearance of particles with square local order."
    },
    {
        "anchor": "Collapsing lattice animals and lattice trees in two dimensions: We present high statistics simulations of weighted lattice bond animals and\nlattice trees on the square lattice, with fugacities for each non-bonded\ncontact and for each bond between two neighbouring monomers. The simulations\nare performed using a newly developed sequential sampling method with\nresampling, very similar to the pruned-enriched Rosenbluth method (PERM) used\nfor linear chain polymers. We determine with high precision the line of second\norder transitions from an extended to a collapsed phase in the resulting\n2-dimensional phase diagram. This line includes critical bond percolation as a\nmulticritical point, and we verify that this point divides the line into two\ndifferent universality classes. One of them corresponds to the collapse driven\nby contacts and includes the collapse of (weakly embeddable) trees, but the\nother is {\\it not yet} bond driven and does not contain the Derrida-Herrmann\nmodel as special point. Instead it ends at a multicritical point $P^*$ where a\ntransition line between two collapsed phases (one bond-driven and the other\ncontact-driven) sparks off. The Derrida-Herrmann model is representative for\nthe bond driven collapse, which then forms the fourth universality class on the\ntransition line (collapsing trees, critical percolation, intermediate regime,\nand Derrida-Herrmann). We obtain very precise estimates for all critical\nexponents for collapsing trees. It is already harder to estimate the critical\nexponents for the intermediate regime. Finally, it is very difficult to obtain\nwith our method good estimates of the critical parameters of the\nDerrida-Herrmann universality class. As regards the bond-driven to\ncontact-driven transition in the collapsed phase, we have some evidence for its\nexistence and rough location, but no precise estimates of critical exponents.",
        "positive": "A thermodynamic unification of jamming: Fragile materials ranging from sand to fire-retardant to toothpaste are able\nto exhibit both solid and fluid-like properties across the jamming transition.\nUnlike ordinary fusion, systems of grains, foams and colloids jam and cease to\nflow under conditions that still remain unknown. Here we quantify jamming via a\nthermodynamic approach by accounting for the structural ageing and the\nshear-induced compressibility of dry sand. Specifically, the jamming threshold\nis defined using a non-thermal temperature that measures the 'fluffiness' of a\ngranular mixture. The thermodynamic model, casted in terms of pressure,\ntemperature and free-volume, also successfully predicts the entropic data of\nfive molecular glasses. Notably, the predicted configurational entropy avoids\nthe Kauzmann paradox entirely. Without any free parameters, the proposed\nequation-of-state also governs the mechanism of shear-banding and the\nassociated features of shear-softening and thickness-invariance."
    },
    {
        "anchor": "Isolating the enhanced memory of a glassy system: Studies of glassy systems have shown how cyclic driving forms memories of\namplitude. We explore how choice of driving protocol reveals dramatically\ndifferent features of this memory. We model rearranging soft spots in sheared\namorphous solids as hysterons. Cyclic shear with positive and negative shear\nstrain reveals a return-point memory of multiple strains known from experiments\nand molecular dynamics simulations, while asymmetric driving (e.g. only\npositive shear strains) suppresses multiple memories. However, when we\nintroduce frustrated interactions between hysterons, we identify a different\nmechanism that restores multiple memories for asymmetric driving and can be\nused for design. Our work suggests that this enhanced memory is a signature of\nfrustration.",
        "positive": "Foundations of Dissipative Particle Dynamics: We derive a mesoscopic modeling and simulation technique that is very close\nto the technique known as dissipative particle dynamics. The model is derived\nfrom molecular dynamics by means of a systematic coarse-graining procedure.\nThus the rules governing our new form of dissipative particle dynamics reflect\nthe underlying molecular dynamics; in particular all the underlying\nconservation laws carry over from the microscopic to the mesoscopic\ndescriptions. Whereas previously the dissipative particles were spheres of\nfixed size and mass, now they are defined as cells on a Voronoi lattice with\nvariable masses and sizes. This Voronoi lattice arises naturally from the\ncoarse-graining procedure which may be applied iteratively and thus represents\na form of renormalisation-group mapping. It enables us to select any desired\nlocal scale for the mesoscopic description of a given problem. Indeed, the\nmethod may be used to deal with situations in which several different length\nscales are simultaneously present. Simulations carried out with the present\nscheme show good agreement with theoretical predictions for the equilibrium\nbehavior."
    },
    {
        "anchor": "Long-lived Giant Number Fluctuations in a Swarming Granular Nematic: Coherently moving flocks of birds, beasts or bacteria are examples of living\nmatter with spontaneous orientational order. How do these systems differ from\nthermal equilibrium systems with such liquid-crystalline order? Working with a\nfluidized monolayer of macroscopic rods in the nematic liquid crystalline\nphase, we find giant number fluctuations consistent with a standard deviation\ngrowing linearly with the mean, in contrast to any situation where the Central\nLimit Theorem applies. These fluctuations are long-lived, decaying only as a\nlogarithmic function of time. This shows that flocking, coherent motion and\nlarge-scale inhomogeneity can appear in a system in which particles do not\ncommunicate except by contact.",
        "positive": "Two-Dimensional Vesicle Hydrodynamics from Hydrophobic Attraction\n  Potential: We develop a new model, to our knowledge, for the many-body hydrodynamics of\namphiphilic Janus particles suspended in a viscous background flow. The Janus\nparticles interact through a hydrophobic attraction potential that leads to\nself-assembly into bilayer structures. We adopt an efficient integral equation\nmethod for solving the screened Laplace equation for hydrophobic attraction and\nfor solving the mobility problem for hydrodynamic interactions. The integral\nequation formulation accurately captures both interactions for near touched\nboundaries. Under a linear shear flow, we observe the tank-treading deformation\nin a two-dimensional vesicle made of Janus particles. The results yield\nmeasurements of inter-monolayer friction, membrane permeability, and at large\nshear rates, membrane rupture. The simulations studies include a vesicle in\nparabolic flow and vesicle-vesicle interactions in shear and extensional flows.\nThe hydrodynamics of the Janus particles vesicle replicate the behaviour of an\ninextensible elastic vesicle membrane."
    },
    {
        "anchor": "Microswimmers near corrugated, periodic surfaces: We explore hydrodynamic interactions between microswimmers and corrugated, or\nrough, surfaces, as found often in biological systems and microfluidic devices.\nUsing the Lorentz reciprocal theorem for viscous flows we derive exact\nexpressions for the roughness-induced velocities up to first order in the\nsurface-height fluctuations and provide solutions for the translational and\nangular velocities valid for arbitrary surface shapes. We apply our theoretical\npredictions to elucidate the impact of a periodic, wavy surface on the\nvelocities of microswimmers modeled in terms of a superposition of Stokes\nsingularities. Our findings, valid in the framework of a far-field analysis,\nshow that the roughness-induced velocities vary non-monotonically with the\nwavelength of the surface. For wavelengths comparable to the swimmer-surface\ndistance a pusher can experience a repulsive contribution due to the reflection\nof flow fields at the edge of a surface cavity, which decreases the overall\nattraction to the wall.",
        "positive": "Superselective adsorption of multivalent polymeric particles: Multivalency is a common biological mechanism of formation of strong\nreversible and selective bonds by grouping weak bonds. Polymers often act as a\nscaffold to which multiple binding groups are attached. Here I present an\nanalytical theory allowing to calculate avidity and selectivity for multivalent\npolymeric particles using tools from the theory of associating fluids. I\nexplicitly take into account conformational degrees of freedom of a polymeric\nscaffold and discuss how they affect superselectivity. I also consider linear\npolymeric particles with two types of ligands and show that superselectivity\ndoes not depend on the sequence of ligands along the backbone for a Gaussian\nchain with short linkers."
    },
    {
        "anchor": "Short-time motion of Brownian particles in a shear flow: The short-time motion of Brownian particles in an incompressible Newtonian\nfluid under shear, in which the fluid inertia becomes important, was\ninvestigated by direct numerical simulation of particulate flows.\nThree-dimensional simulations were performed, wherein external forces were\nintroduced to approximately form Couette flows throughout the entire system\nwith periodic boundary conditions. In order to examine the validity of the\nmethod, the mean square displacement of a single spherical particle in a simple\nshear flow was calculated, and these results were compared with a hydrodynamic\nanalytical solution that includes the effects of the fluid inertia. Finally,\nthe dynamical behavior of a monodisperse dispersion composed of repulsive\nspherical particles was examined on short time scales, and the shear-induced\ndiffusion coefficients were measured for several volume fractions up to 0.50.",
        "positive": "Structural precursor to freezing: An integral equation study: Recent simulation studies have drawn attention to the shoulder which forms in\nthe second peak of the radial distribution function of hard-spheres at\ndensities close to freezing and which is associated with local crystalline\nordering in the dense fluid. We address this structural precursor to freezing\nusing an inhomogeneous integral equation theory capable of describing local\npacking constraints to a high level of accuracy. The addition of a short-range\nattractive interaction leads to a well known broadening of the fluid-solid\ncoexistence region as a function of attraction strength. The appearence of a\nshoulder in our calculated radial distribution functions is found to be\nconsistent with the broadened coexistence region for a simple model potential,\nthus demonstrating that the shoulder is not exclusively a high density packing\neffect."
    },
    {
        "anchor": "Dynamical density functional theory based modelling of tissue dynamics:\n  application to tumour growth: We present a theoretical framework based on an extension of dynamical density\nfunctional theory (DDFT) for describing the structure and dynamics of cells in\nliving tissues and tumours. DDFT is a microscopic statistical mechanical theory\nfor the time evolution of the density distribution of interacting many-particle\nsystems. The theory accounts for cell pair-interactions, different cell types,\nphenotypes and cell birth and death processes (including cell division), in\norder to provide a biophysically consistent description of processes bridging\nacross the scales, including describing the tissue structure down to the level\nof the individual cells. Analysis of the model is presented for a single\nspecies and a two-species cases, the latter aimed at describing competition\nbetween tumour and healthy cells. In suitable parameter regimes, model results\nare consistent with biological observations. Of particular note, divergent\ntumour growth behaviour, mirroring metastatic and benign growth\ncharacteristics, are shown to be dependent on the cell pair-interaction\nparameters.",
        "positive": "From viscous fluids to elastic solids: A perspective on the glass\n  transition: A theory for the non-local stress in liquids captures the crossover from\nviscous to elastic correlations upon supercooling. It explains the emergence of\nlong-ranged stress fields in glass which originate from the coupling of shear\nstress to transverse deformations. The Goldstone mode in colloidal glass is\nshown to be diffusive."
    },
    {
        "anchor": "Thermodynamics and Kinetics of a Go Proteinlike Heteropolymer Model with\n  Two-State Folding Characteristics: We present results of Monte Carlo computer simulations of a coarse-grained\nhydrophobic-polar Go-like heteropolymer model and discuss thermodynamic\nproperties and kinetics of an exemplified heteropolymer, exhibiting two-state\nfolding behavior. It turns out that general, characteristic folding features of\nrealistic proteins with a single free-energy barrier can also be observed in\nthis simplified model, where the folding transition is primarily driven by the\nhydrophobic force.",
        "positive": "Kinetic mechanism of chain folding in polymer crystallization: I develop a kinetic mechanism to explain chain folding in polymer\ncrystallization which is based on the competition between the formation of\nstems, which is due to frequent occupations of trans states along the chains in\nthe supercooled polymer melt, and the random coil structure of the polymer\nchains. Setting equal the average formation time of stems of length $% d_l$\nwith the Rouse time of a piece of polymer of the same arc length $d_l$ yields a\nlower bound for the thickness of stems and bundles. The estimated lamellar\nthickness is inversely proportional to the supercooling. The present approach\nemphasizes the importance of repulsive interactions in polymer crystallization,\nwhich are expected to be responsible for the logarithmic lamellar thickening\nand the increase of lamellar thickness with pressure. An expression for the\ngrowth rate is derived by considering the growth as a dynamic multistage\nprocess."
    },
    {
        "anchor": "Nonlinear three-wave interaction in marine sediments: Nonlinear interaction of three acoustic waves in a sandy sediment is studied\nin the frequency range where there is a considerable wave velocity dispersion.\nThe possibility of an experimental observation of the generation of a sound\nwave by two pump waves propagating at an angle to each other is estimated.",
        "positive": "Attractive Inverse Square Potential, U(1) Gauge, and Winding Transitions: The inverse square potential arises in a variety of different quantum\nphenomena, yet notoriously it must be handled with care: it suffers from\npathologies rooted in the mathematical foundations of quantum mechanics. We\nshow that its recently studied conformality-breaking corresponds to an\ninfinitely smooth winding-unwinding topological transition for the {\\it\nclassical} statistical mechanics of a one-dimensional system: this describes\nthe the tangling/untangling of floppy polymers under a biasing torque. When the\nratio between torque and temperature exceeds a critical value the polymer\nundergoes tangled oscillations, with an extensive winding number. At lower\ntorque or higher temperature the winding number per unit length is zero.\nApproaching criticality, the correlation length of the order parameter---the\nextensive winding number---follows a Kosterlitz-Thouless type law. The model is\ndescribed by the Wilson line of a (0+1) $U(1)$ gauge theory, and applies to the\ntangling/untangling of floppy polymers and to the winding/diffusing kinetics in\ndiffusion-convection-reactions."
    },
    {
        "anchor": "Water-methanol mixture confined in a graphene slit-pore: Efficient and sustainable techniques for separating water-methanol mixtures\nare in high demand in the industry. Recent studies have revealed that membranes\nand 2D materials could achieve such separation. In our research, we explore the\nimpact of a nanoconfining graphene slit-pore on the dynamics and structure of\nwater-methanol mixtures. By Molecular Dynamics simulations of a coarse-grained\nmodel for water mixtures containing up to 25% methanol, we show that, for\nappropriate pore sizes, water tends to occupy the center of the pore. In\ncontrast, methanol's apolar moiety accumulates near the hydrophobic walls.\nAdditionally, modifying the pore's width leads to a non-monotonic change in the\ndiffusivity of each component. However, water always diffuses faster than\nmethanol, implying that it should be possible to identify an optimal\nconfiguration for water-methanol separation based on physical mechanisms. Our\ncalculations indicate that one of the more effective pore sizes, 12.5{\\AA}, is\nalso mechanically stable, minimizing the energy cost of a possible filtering\nmembrane.",
        "positive": "Shear thickening of cornstarch suspensions as a re-entrant jamming\n  transition: We study the rheology of cornstarch suspensions, a dense system of\nnon-Brownian particles that exhibits shear thickening, i.e. a viscosity that\nincreases with increasing shear rate. Using MRI velocimetry we show that the\nsuspension has a yield stress. From classical rheology it follows that as a\nfunction of the applied stress the suspension is first solid (yield stress),\nthen liquid and then solid again when it shear thickens. The onset shear rate\nfor thickening is found to depend on the measurement geometry: the smaller the\ngap of the shear cell, the lower the shear rate at which thickening occurs.\nShear thickening can then be interpreted as the consequence of the Reynolds\ndilatancy: the system under flow wants to dilate but instead undergoes a\njamming transition because it is confined, as confirmed by measurement of the\ndilation of the suspension as a function of the shear rate."
    },
    {
        "anchor": "A classical density functional from machine learning and a convolutional\n  neural network: We use machine learning methods to approximate a classical density\nfunctional. As a study case, we choose the model problem of a Lennard Jones\nfluid in one dimension where there is no exact solution available and training\ndata sets must be obtained from simulations. After separating the excess free\nenergy functional into a \"repulsive\" and an \"attractive\" part, machine learning\nfinds a functional in weighted density form for the attractive part. The\ndensity profile at a hard wall shows good agreement for thermodynamic\nconditions beyond the training set conditions. This also holds for the equation\nof state if it is evaluated near the training temperature. We discuss the\napplicability to problems in higher dimensions.",
        "positive": "Thermal Excitations of Warped Membranes: We explore thermal fluctuations of thin planar membranes with a frozen\nspatially-varying background metric and a shear modulus. We focus on a special\nclass of $D$-dimensional ``warped membranes'' embedded in a $d-$dimensional\nspace with $d\\ge D+1$ and a preferred height profile characterized by quenched\nrandom Gaussian variables $\\{h_\\alpha({\\bf q})\\}$, $\\alpha=D+1,\\ldots, d$, in\nFourier space with zero mean and a power law variance $\\overline{ h_\\alpha({\\bf\nq}_1) h_\\beta({\\bf q}_2) } \\sim \\delta_{\\alpha, \\beta} \\, \\delta_{{\\bf q}_1,\n-{\\bf q}_2} \\, q_1^{-d_h}$. The case $D=2$, $d=3$ with $d_h = 4$ could be\nrealized by flash polymerizing lyotropic smectic liquid crystals. For $D <\n\\max\\{4, d_h\\}$ the elastic constants are non-trivially renormalized and become\nscale dependent. Via a self consistent screening approximation we find that the\nrenormalized bending rigidity increases for small wavevectors ${{\\bf q}}$ as\n$\\kappa_R \\sim q^{-\\eta_f}$, while the in-hyperplane elastic constants decrease\naccording to $\\lambda_R,\\ \\mu_R \\sim q^{+\\eta_u}$. The quenched background\nmetric is relevant (irelevant) for warped membranes characterized by exponent\n$d_h > 4 - \\eta_f^{(F)}$ ($d_h < 4 - \\eta_f^{(F)}$), where $\\eta_f^{(F)}$ is\nthe scaling exponent for tethered surfaces with a flat background metric, and\nthe scaling exponents are related through $\\eta_u + \\eta_f = d_h - D$ ($\\eta_u\n+ 2 \\eta_f=4-D$)."
    },
    {
        "anchor": "A new equation of state of a flexible-chain polyelectrolyte solution:\n  Phase equilibria and osmotic pressure in the salt-free case: We develop a first-principle equation of state of salt-free polyelectrolyte\nsolution in the limit of infinitely long flexible polymer chains in the\nframework of a field-theoretical formalism beyond the linear Debye-Hueckel\ntheory and predict a liquid-liquid phase separation induced by a strong\ncorrelation attraction. As a reference system we choose a set of two subsystems\n- charged macromolecules immersed in a structureless oppositely charged\nbackground created by counterions (polymer one component plasma) and\ncounterions immersed in oppositely charged background created by polymer chains\n(hard-core one component plasma). We calculate the excess free energy of\npolymer one component plasma in the framework of Modified Random Phase\nApproximation, whereas a contribution of charge densities fluctuations of\nneutralizing backgrounds we evaluate at the level of Gaussian approximation. We\nshow that our theory is in a very good agreement with the results of\nMonte-Carlo and MD simulations for critical parameters of liquid-liquid phase\nseparation and osmotic pressure in a wide range of monomer concentration above\nthe critical point, respectively.",
        "positive": "Demixing cascades in cluster crystals: In a cluster crystal, each lattice site is occupied by multiple soft-core\nparticles. As the number density is increased at zero temperature, a `cascade'\nof isostructural phase transitions can occur between states whose site\noccupancy differs by unity. For low but finite temperature, each of these\ntransitions terminates in a critical point. Using tailored Monte Carlo\nsimulation techniques we have studied such demixing cascades in systems of soft\nparticles interacting via potentials of the generalized exponential form\n$u(r)=\\epsilon\\exp[-(r/\\sigma)^n]$. We have estimated the critical parameters\nof the first few transitions in the cascade as a function of the softness\nparameter $n$. The critical temperature and pressure exhibit non-monotonic\nbehaviour as $n$ is varied, although the critical chemical potential remains\nmonotonic. The trends for the pressure and chemical potential are confirmed by\ncell model calculations at zero temperature. As $n\\to 2^+$, all the transitions\nthat we have observed are preempted by melting although we cannot rule out that\nclustering transitions survive at high density."
    },
    {
        "anchor": "Curvature-driven feedback on aggregation-diffusion of proteins in lipid\n  bilayers: Membrane bending is an extensively studied problem from both modeling and\nexperimental perspectives because of the wide implications of curvature\ngeneration in cell biology. Many of the curvature generating aspects in\nmembranes can be attributed to interactions between proteins and membranes.\nThese interactions include protein diffusion and formation of aggregates due to\nprotein-protein interactions in the plane of the membrane. Recently, we\ndeveloped a model that couples the in-plane flow of lipids and diffusion of\nproteins with the out-of-plane bending of the membrane. Building on this work,\nhere, we focus on the role of explicit aggregation of proteins on the surface\nof the membrane in the presence of membrane bending and diffusion. We develop a\ncomprehensive framework that includes lipid flow, membrane bending, the entropy\nof protein distribution, along with an explicit aggregation potential and\nderive the governing equations for the coupled system. We compare this\nframework to the Cahn-Hillard formalism to predict the regimes in which the\nproteins form patterns on the membrane. We demonstrate the utility of this\nmodel using numerical simulations to predict how aggregation and diffusion,\nwhen coupled with curvature generation, can alter the landscape of\nmembrane-protein interactions.",
        "positive": "A Rheological Analogue for Brownian Motion with Hydrodynamic Memory: When the density of the fluid surrounding suspended Brownian particles is\nappreciable, in addition to the forces appearing in the traditional Ornstein\nand Uhlenbeck theory of Brownian motion, additional forces emerge as the\ndisplaced fluid in the vicinity of the randomly moving Brownian particle acts\nback on the particle giving rise to long-range force correlations which\nmanifest as a ``long-time tail'' in the decay of the velocity autocorrelation\nfunction known as hydrodynamic memory. In this paper, after recognizing that\nfor Brownian particles immersed in a Newtonian, viscous fluid, the hydrodynamic\nmemory term in the generalized Langevin equation is essentially the 1/2\nfractional derivative of the velocity of the Brownian particle, we present a\nrheological analogue for Brownian motion with hydrodynamic memory which\nconsists of a linear dashpot of a fractional Scott-Blair element and an\ninerter. The synthesis of the proposed mechanical network that is suggested\nfrom the structure of the generalized Langevin equation simplifies appreciably\nthe calculations of the mean-square displacement and its time-derivatives which\ncan also be expressed in terms of the two-parameter Mittag--Leffler function."
    },
    {
        "anchor": "Thermal interface fluctuations of liquids and viscoelastic materials: Spectra of thermal fluctuations of a wide range of interfaces, from\nliquid/air, viscoelastic material/air, liquid/liquid, to liquid/viscoelastic\nmaterial interfaces, were measured over 100 Hz to 10 MHz frequency range. The\nobtained spectra were compared with the fluctuation theory of interfaces, and\nfound to be mostly in quite good agreement, when the theory was generalized to\napply to thermal fluctuations of liquid/viscoelastic material interfaces. The\nspectra were measured using a system that combines light reflection,\nstatistical noise reduction through averaged correlations, and confocal\nmicroscopy. It requires only a small area of the interface ($\\sim1\\,\\mu$m$^2$)\n, relatively short times for measurements ($\\lesssim$few min), and can also be\napplied to highly viscous materials.",
        "positive": "Liquid crystal phases with unusual structures and physical properties\n  formed by acute-angle bent-core molecules: Liquid crystals formed by acute-angle bent-core (ABC) molecules with a 1,7\nnaphthalene central core show an intriguing phase behavior with the nematic\nphase accompanied by poorly understood additional phases. In this work, we\ncharacterize the physical properties of an ABC material, such as birefringence,\ndielectric permittivities, elastic constants, and surface alignment, and\npresent X-ray diffraction and transmission electron microscopy studies of their\nordering. The ABC molecular shape resembling the letter $\\lambda$ yields a very\nsmall splay elastic constant in the uniaxial nematic phase and results in the\nformation of a tetragonal positionally ordered columnar phase consisting of\nmolecular columns with a uniform uniaxial director that can be bent but not\nsplayed."
    },
    {
        "anchor": "A lattice model of ternary mixtures of lipids and cholesterol with\n  tunable domain sizes: Much of our understanding of the physical properties of raft domains in\nbiological membranes, and some insight into the mechanisms underlying their\nformation stem from atomistic simulations of simple model systems, especially\nternary mixtures consisting of saturated and unsaturated lipids, and\ncholesterol (Chol). To explore the properties of such systems at large spatial\nscales, we here present a simple ternary mixture lattice model, involving a\nsmall number of nearest neighbor interaction terms. Monte Carlo simulations of\nmixtures with different compositions show an excellent agreement with\nexperimental and atomistic simulation observations across multiple scale,\nranging from the local distributions of lipids to the phase diagram of the\nsystem. The simplicity of the model allows us to identify the roles played by\nthe different interactions between components, and the interplay between them.\nImportantly, by changing the value of one of the model parameters, we can tune\nthe size of the liquid-ordered domains, thereby to simulate both Type II\nmixtures exhibiting macroscopic phase separation and Type I mixtures with\nnanoscopic domains. The Type II mixture simulation results fit well to the\nexperimentally-determined phase diagram of mixtures containing saturated\nDPPC/unsaturated DOPC/Chol. When the tunable parameter is changed, we obtain\nthe Type I version of DPPC/DOPC/Chol, i.e., a mixture not showing thermodynamic\nphase transitions but one that may be fitted to the same phase diagram if local\nmeasures are used to distinguish between the different states. Our model\nresults suggest that short range packing is likely to be a key regulator of the\nstability and size distribution of biological rafts.",
        "positive": "Timescales of emulsion formation caused by anisotropic particles: Particle stabilized emulsions have received an enormous interest in the\nrecent past, but our understanding of the dynamics of emulsion formation is\nstill limited. For simple spherical particles, the time dependent growth of\nfluid domains is dominated by the formation of droplets, particle adsorption\nand coalescence of droplets (Ostwald ripening), which eventually can be almost\nfully blocked due to the presence of the particles. Ellipsoidal particles are\nknown to be more efficient stabilizers of fluid interfaces than spherical\nparticles and their anisotropic shape and the related additional rotational\ndegrees of freedom have an impact on the dynamics of emulsion formation. In\nthis paper, we investigate this point by means of simple model systems\nconsisting of a single ellipsoidal particle or a particle ensemble at a flat\ninterface as well as a particle ensemble at a spherical interface. By applying\ncombined multicomponent lattice Boltzmann and molecular dynamics simulations we\ndemonstrate that the anisotropic shape of ellipsoidal particles causes two\nadditional timescales to be of relevance in the dynamics of emulsion formation:\na relatively short timescale can be attributed to the adsorption of single\nparticles and the involved rotation of particles towards the interface. As soon\nas the interface is jammed, however, capillary interactions between the\nparticles cause a local reordering on very long timescales leading to a\ncontinuous change in the interface configuration and increase of interfacial\narea. This effect can be utilized to counteract the thermodynamic instability\nof particle stabilized emulsions and thus offers the possibility to produce\nemulsions with exceptional stability."
    },
    {
        "anchor": "Salt-Induced Counterion-Mobility Anomaly in Polyelectrolyte\n  Electrophoresis: We study the electrokinetics of a single polyelectrolyte chain in salt\nsolution using hydrodynamic simulations. The salt-dependent chain mobility\ncompares well with experimental DNA data. The mobility of condensed counterions\nexhibits a salt-dependent change of sign, an anomaly that is also reflected in\nthe counterion excess conductivity. Using Green's function techniques this\nanomaly is explained by electrostatic screening of the hydrodynamic\ninteractions between chain and counterions.",
        "positive": "Shear induced solidification of athermal systems with weak attraction: We find that unjammed packings of frictionless particles with rather weak\nattraction can always be driven into solid-like states by shear. The structure\nof shear-driven solids evolves continuously with packing fraction from gel-like\nto jamming-like, but is almost independent of the shear stress. In contrast,\nboth the density of vibrational states (DOVS) and force network evolve\nprogressively with the shear stress. There exists a packing fraction\nindependent shear stress $\\sigma_c$, at which the shear-driven solids are\nisostatic and have a flattened DOVS. Solid-like states induced by a shear\nstress greater than $\\sigma_c$ possess properties of marginally jammed solids\nand are thus strictly-defined shear jammed states. Below $\\sigma_c$, states at\nall packing fractions are under isostaticity and share common features in the\nDOVS and force network, although their structures can be rather different. Our\nstudy reveals the significance of the shear stress in determining properties of\nshear-driven solids and leads to an enriched jamming phase diagram for weakly\nattractive particles."
    },
    {
        "anchor": "A Modular Origami-inspired Mechanical Metamaterial: Mechanical metamaterials with complex microstructures have superior physical\nproperties such as graded stiffness, negative Poisson's ratio, and advantage in\nenergy absorption. In recent years, origami provide many inspirations in the\ngeometry structure of the metamaterials. Here we present a modular origami\ninspired reconfigurable metamaterial. Our approach exploits a transformable\nmodule consisted of the Sarrus linkage and planar four-bar linkage, and the\nmodules are connected following a tessellation pattern to form a periodic\nstructure. Different arrangements, module shapes and grid pattern of the\nmetamaterial are discussed, and the loading capacity and stiffness variation\nare analysed experimentally. The proposed material can be used to realize\nreconfigurable structures or architectures over a wide range of length scales.",
        "positive": "Orientational Order in Liquids upon Condensation in Nanochannels: An\n  Optical Birefringence Study on Rodlike and Disclike Molecules in Monolithic\n  Mesoporous Silica: We present high-resolution optical birefringence measurements upon sequential\nfilling of an array of parallel-aligned nanochannels (14~nm mean diameter) with\nrod-like (acetonitrile) and disc-like (hexafluorobenzene) molecules. We will\ndemonstrate that such birefringence isotherms, when performed simultaneously\nwith optically isotropic and index-matched counterparts (neopentane and\nhexafluoromethane), allow one to characterize the orientational state of the\nconfined liquids with a high accuracy as a function of pore filling. The pore\ncondensates are almost bulk-like, optically isotropic liquids. For both\nanisotropic species we find, however, a weak orientational order (of a few\npercent at maximum) upon film-condensation in the monolithic mesoporous\nmembrane. It occurs upon formation of the second and third adsorbed layer,\nonly, and vanishes gradually upon onset of capillary condensation. Presumably,\nit originates in the breaking of the full rotational symmetry of the\ninteraction potential at the cylindrical, free liquid-vapor interface in the\nfilm-condensed state rather than at the silica-liquid interface. This\nconclusion is corroborated by comparisons of our experimental results with\nmolecular dynamics simulations reported in the literature."
    },
    {
        "anchor": "Generalization of distance to higher dimensional objects: The measurement of distance between two objects is generalized to the case\nwhere the objects are no longer points but are one-dimensional. Additional\nconcepts such as non-extensibility, curvature constraints, and non-crossing\nbecome central to the notion of distance. Analytical and numerical results are\ngiven for some specific examples, and applications to biopolymers are\ndiscussed.",
        "positive": "Harnessing Interpretable Machine Learning for Holistic Inverse Design of\n  Origami: This work harnesses interpretable machine learning methods to address the\nchallenging inverse design problem of origami-inspired systems. We show that a\ndecision tree-random forest method is particularly suitable for fitting origami\ndatabases, containing both design features and functional performance, to\ngenerate human-understandable decision rules for the inverse design of\nfunctional origami. First, the tree method is unique because it can handle\ncomplex interactions between categorical features and continuous features,\nallowing it to compare different origami patterns for a design. Second, this\ninterpretable method can tackle multi-objective problems for designing\nfunctional origami with multiple and multi-physical performance targets.\nFinally, the method can extend existing shape-fitting algorithms for origami to\nconsider non-geometrical performance. The proposed framework enables holistic\ninverse design of origami, considering both shape and function, to build novel\nreconfigurable structures for various applications such as metamaterials,\ndeployable structures, soft robots, biomedical devices, and many more."
    },
    {
        "anchor": "The shape of jamming arches in two-dimensional deposits of granular\n  materials: We present experimental results on the shape of arches that block the outlet\nof a two dimensional silo. For a range of outlet sizes, we measure some\nproperties of the arches such as the number of particles involved, the span,\nthe aspect ratio, and the angles between mutually stabilizing particles. These\nmeasurements shed light on the role of frictional tangential forces in arching.\nIn addition, we find that arches tend to adopt an aspect ratio (the quotient\nbetween height and half the span) close to one, suggesting an isotropic load.\nThe comparison of the experimental results with data from numerical models of\nthe arches formed in the bulk of a granular column reveals the similarities of\nboth, as well as some limitations in the few existing models.",
        "positive": "Deformation of loops in 2D packing of flexible rods: The injection of a long flexible rod into a two-dimensional domain yields a\ncomplex pattern commonly studied through elasticity theory, packing analysis,\nand fractal geometries. \"Loop\" is a one-vertex entity that is naturally formed\nin this system. The role of the elastic features of each loop in 2D packing has\nnot yet been discussed. In this work, we point out how the shape of a given\nloop in the complex structure allows estimating local deformations and forces.\nFirst, we build sets of symmetric free loops and performed compression\nexperiments. Then, tight packing configurations are analyzed by using image\nprocessing. We found that the dimensions of the loops, confined or not, obey\nthe same dependence on the deformation. The result is consistent with a simple\nmodel based on 2D elastic theory for filaments, where the rod adopts the shape\nof Euler's elasticas between its contact points. The force and the stored\nenergy are obtained from numerical integration of the analytic expressions. In\nan additional experiment, we obtain that the compression force for deformed\nloops corroborates the theoretical findings. The importance of the shape of the\nloop is discussed and we hope that the theoretical curves may allow statistical\nconsiderations in future investigations."
    },
    {
        "anchor": "Creep control in soft particle packings: Granular packings display a wealth of mechanical features which are of\nwidespread significance. One of these features is creep: the slow deformation\nunder applied stress. Creep is common for many other amorphous materials such\nas many metals and polymers. The slow motion of creep is challenging to\nunderstand, probe and control. We probe the creep properties of packings of\nsoft spheres with a sinking ball viscometer. We find that in our granular\npackings, creep persists up to large strains and has a power law form, with\ndiffusive dynamics. The creep amplitude is exponentially dependent on both\napplied stress and the concentration of hydrogel, suggesting that a competition\nbetween driving and confinement determines the dynamics. Our results provide\ninsights into the mechanical properties of soft solids and the scaling laws\nprovide a clear benchmark for new theory that explains creep, and provide the\ntantalizing prospect that creep can be controlled by a boundary stress.",
        "positive": "A multi-axis confocal rheoscope for studying shear flow of structured\n  fluids: We present a new design for a confocal rheoscope that enables uniform\nuniaxial or biaxial shear. The design consists of two precisely-positioned\nparallel plates with a gap that can be adjusted down to 2$\\pm$0.1 \\mu m,\nallowing for the exploration of confinement effects. By using our shear cell in\nconjunction with a biaxial force measurement device and a high-speed confocal\nmicroscope, we are able to measure the real-time biaxial stress while\nsimultaneously imaging the material 3D structure. We illustrate the importance\nof the instrument capabilities by discussing the applications of this\ninstrument in current and future research topics in colloidal suspensions."
    },
    {
        "anchor": "Unsupervised learning of sequence-specific aggregation behavior for a\n  model copolymer: We apply a recently developed unsupervised machine learning scheme for local\natomic environments to characterize large-scale, disordered aggregates formed\nby sequence-defined macromolecules. This method provides new insight into the\nstructure of these disordered, dilute aggregates, which has proven difficult to\nunderstand using collective variables manually derived from expert knowledge.\nIn contrast to such conventional order parameters, we are able to classify the\nglobal aggregate structure directly using descriptions of the local\nenvironments. The resulting characterization provides a deeper understanding of\nthe range of possible self-assembled structures and their relationships to each\nother. We also provide a detailed analysis of the effects of finite system\nsize, stochasticity, and kinetics of these aggregates based on the learned\ncollective variables. Interestingly, we find that the spatiotemporal evolution\nof systems in the learned latent space is smooth and continuous, despite being\nderived from only a single snapshot from each of about 1000 monomer sequences.\nThese results demonstrate the insight which can be gained by applying\nunsupervised machine learning to soft matter systems, especially when suitable\norder parameters are not known.",
        "positive": "Compaction of granular material inside confined geometries: In both nature and engineering, loosely packed granular materials are often\ncompacted inside confined geometries. Here, we explore such behaviour in a\nquasi-two dimensional geometry, where parallel rigid walls provide the\nconfinement. We use the discrete element method to investigate the stress\ndistribution developed within the granular packing as a result of compaction\ndue to the displacement of a rigid piston. We observe that the stress within\nthe packing increases exponentially with the length of accumulated grains, and\nshow an extension to current analytic models which fits the measured stress.\nThe micromechanical behaviour is studied for a range of system parameters, and\nthe limitations of existing analytic models are described. In particular, we\nshow the smallest sized systems which can be treated using existing models.\nAdditionally, the effects of increasing piston rate, and variations of the\ninitial packing fraction, are described."
    },
    {
        "anchor": "Contact mechanics: relation between interfacial separation and load: I study the contact between a rigid solid with a randomly rough surface and\nan elastic block with a flat surface. I derive a relation between the (average)\ninterfacial separation $u$ and the applied normal squeezing pressure $p$. I\nshow that for non-adhesive inte raction and small applied pressure, p is\nproportional to exp (-u/u_0), in good agreement with recent experimental\nobservation.",
        "positive": "Colloidal particles at a nematic-isotropic interface: effects of\n  confinement: When captured by a flat nematic-isotropic interface, colloidal particles can\nbe dragged by it. As a result spatially periodic structures may appear, with\nthe period depending on a particle mass, size, and interface\nvelocity~\\cite{west.jl:2002}. If liquid crystal is sandwiched between two\nsubstrates, the interface takes a wedge-like shape, accommodating the\ninterface-substrate contact angle and minimizing the director distortions on\nits nematic side. Correspondingly, particles move along complex trajectories:\nthey are first captured by the interface and then `glide' towards its vertex\npoint. Our experiments quantify this scenario, and numerical minimization of\nthe Landau-de Gennes free energy allow for a qualitative description of the\ninterfacial structure and the drag force."
    },
    {
        "anchor": "Microscopic Origin of Shear Relaxation in Strongly Coupled Yukawa\n  Liquids: We report accurate molecular dynamics calculations of the shear stress\nrelaxation in a two-dimensional strongly coupled Yukawa liquid over a wide\nrange of the Coulomb coupling strength $\\Gamma$ and the Debye screening\nparameter $\\kappa$. Our data on the relaxation times of the ideal- , excess-\nand total shear stress auto-correlation ($\\tau^{id}_M, \\tau^{ex}_M, \\tau_M$\nrespectively) along with the lifetime of local atomic connectivity $\\tau_{LC}$\nleads us to the following important observation. Below a certain crossover\n$\\Gamma_c(\\kappa)$, $\\tau_{LC} \\rightarrow \\tau^{ex}_M$, directly implying that\nhere $\\tau_{LC}$ is the microscopic origin of the relaxation of excess shear\nstress unlike the case for ordinary liquids where it is the origin of the\nrelaxation of the total shear stress. At $\\Gamma >> \\Gamma_c(\\kappa)$ i.e. in\nthe potential energy dominated regime, $\\tau^{ex}_M\\rightarrow \\tau_M$ meaning\nthat $\\tau^{ex}_M$ can fully account for the elastic or \"solid like\" behavior.",
        "positive": "Structure of saturated RSA ellipse packings: Motivated by the recent observation of liquid glass in suspensions of\nellipsoidal colloids, we examine the structure of (asymptotically) saturated\nRSA ellipse packings. We determine the packing fractions $\\phi_{\\rm s}(\\alpha)$\nto high precision, finding an empirical analytic formula that predicts\n$\\phi_{\\rm s}(\\alpha)$ to within less than $0.1\\%$ for all $\\alpha \\leq 10$.\nThen we explore how these packings' positional-orientational order varies with\n$\\alpha$. We find a transition from tip/side- to side/side-contact-dominated\nstructure at $\\alpha = \\alpha_{\\rm TS} \\simeq 2.4$. At this aspect ratio, the\npeak value $g_{\\rm max}$ of packings' positional-orientational paircorrelation\nfunctions is minimal, and systems can be considered maximally locally\ndisordered. For smaller (larger) $\\alpha$, $g_{\\rm max}$ increases\nexponentially with deceasing (increasing) $\\alpha$. Local nematic order and\nstructures comparable to the precursor domains observed in experiments\ngradually emerge as $\\alpha$ increases beyond $3$. For $\\alpha \\gtrsim 5$,\nsingle-layer lamellae become more prominent, and long-wavelength density\nfluctuations increase with $\\alpha$ as packings gradually approach the rod-like\nlimit."
    },
    {
        "anchor": "Elastoplasticity Mediates Dynamical Heterogeneity Below the\n  Mode-Coupling Temperature: As liquids approach the glass transition temperature, dynamical heterogeneity\nemerges as a crucial universal feature of their behavior. Dynamic facilitation,\nwhere local motion triggers further motion nearby, plays a major role in this\nphenomenon. Here we show that long-range, elastically-mediated facilitation\nappears below the mode-coupling temperature, adding to the short-range\ncomponent present at all temperatures. Our results suggest deep connections\nbetween the supercooled liquid and glass states, and pave the way for a deeper\nunderstanding of dynamical heterogeneity in glassy systems.",
        "positive": "Numerical studies of domains and bubbles of Langmuir monolayers: A numerical algorithm based on the finite element methods has been developed\nto accurately determine the shape of the boundary of a domain containing\n``boojum'' textures. Within the context of the simple model we adopt, the\neffects of both bulk elastic anisotropy and line-tension anisotropy on the\ndomain boundary can be examined. It is found that line-tension anisotropy must\nbe present in order to account for domains with protruding features. Both\nelastic anisotropy and anisotropic line-tension can result in domains with\nindentations. The numerical algorithm has been extended to investigate the\nproblem of a bubble in extended region ordered phase."
    },
    {
        "anchor": "Atomistic Simulations of Magnetic Amorphous Solids: Magnetostriction,\n  Barkhausen noise and novel singularities: We present results of atomistic simulations of a new model of a magnetic\namorphous solid subjected to external mechanical strains and magnetic fields.\nThe model employed offers new perspectives on important effects like Barkhausen\nnoise and magnetostriction. It is shown that the plastic response in such\nsystems exhibit singularities characterized by unexpected exponents requiring\ncareful theoretical reasoning. The spatial structure of the plastic events\nrequires a new coarse grained elasto-magnetic theory which is provided here.",
        "positive": "Reduced model and nonlinear analysis of localized instabilities of\n  residually stressed cylinders under axial stretch: In this paper we present a dimensional reduction to obtain a one-dimensional\nmodel to analyze localized necking or bulging in a residually stressed circular\ncylindrical solid. The nonlinear theory of elasticity is first specialized to\nobtain the equations governing the homogeneous deformation. Then, to analyze\nthe non-homogeneous part, we include higher order correction terms of the\naxisymmetric displacement components leading to a three-dimensional form of the\ntotal potential energy functional. Details of the reduction to the\none-dimensional form are given. We focus on a residually stressed Gent material\nand use numerical methods to solve the governing equations. Two loading\nconditions are considered. In the first, the residual stress is maintained\nconstant, while the axial stretch is used as the loading parameter. In the\nsecond, we keep the pre-stretch constant and monotonically increase the\nresidual stress until bifurcation occurs. We specify initial conditions, find\nthe critical values for localized bifurcation and compute the change in radius\nduring localized necking or bulging growth. Finally, we optimize material\nproperties and use the one-dimensional model to simulate necking or bulging\nuntil the Maxwell values of stretch are reached."
    },
    {
        "anchor": "Understanding Degeneracy of Two-Point Correlation Functions via Debye\n  Random Media: It is well-known that the degeneracy of two-phase microstructures with the\nsame volume fraction and two-point correlation function $S_2(\\mathbf{r})$ is\ngenerally infinite. To elucidate the degeneracy problem explicitly, we examine\nDebye random media, which are entirely defined by a purely exponentially\ndecaying two-point correlation function $S_2(r)$. In this work, we consider\nthree different classes of Debye random media. First, we generate the \"most\nprobable\" class using the Yeong-Torquato construction algorithm [Yeong and\nTorquato, Phys. Rev. E, 57, 495 (1998)]. A second class of Debye random media\nis obtained by demonstrating that the corresponding two-point correlation\nfunctions are effectively realized in the first three space dimensions by\ncertain models of overlapping, polydisperse spheres. A third class is obtained\nby using the Yeong-Torquato algorithm to construct Debye random media that are\nconstrained to have an unusual prescribed pore-size probability density\nfunction. We structurally discriminate these three classes of Debye random\nmedia from one another by ascertaining their other statistical descriptors,\nincluding the pore-size, surface correlation, chord-length probability density,\nand lineal-path functions. We also compare and contrast the percolation\nthresholds as well as the diffusion and fluid transport properties of these\ndegenerate Debye random media. We find that these three classes of Debye random\nmedia are generally distinguished by the aforementioned descriptors and their\nmicrostructures are also visually distinct from one another. Our work further\nconfirms the well-known fact that scattering information is insufficient to\ndetermine the effective physical properties of two-phase media. Additionally,\nour findings demonstrate the importance of the other two-point descriptors\nconsidered here in the design of materials with a spectrum of physical\nproperties.",
        "positive": "Noise induced swarming of active particles: We report on the effect of spatially correlated noise on the velocities of\nself propelled particles. Correlations in the random forces acting on self\npropelled particles can induce directed collective motion, i.e. swarming. Even\nwith repulsive coupling in the velocity directions, which favors a disordered\nstate, strong correlations in the fluctuations can align the velocities locally\nleading to a macroscopic, turbulent velocity field. On the other hand, while\nspatially correlated noise is aligning the velocities locally, the swarming\ntransition to globally directed motion is inhibited when the correlation length\nof the noise is nonzero, but smaller than the system size. We analyze the\nswarming transition in $d$ dimensional space in a mean field model of globally\ncoupled velocity vectors."
    },
    {
        "anchor": "Enhanced diffusion of tracer particles in dilute bacterial suspensions: Swimming bacteria create long-range velocity fields that stir a large volume\nof fluid and move around passive particles dispersed in the fluid. Recent\nexperiments and simulations have shown that long-time mean-squared displacement\nof passive particles in a bath of swimming bacteria exhibits diffusive\nbehaviour with the effective diffusion coefficient significantly larger than\nits thermal counterpart. Comprehensive theoretical prediction of this effective\ndiffusion coefficient and understanding of the enhancement mechanism remain a\nchallenge. Here, we adapt the kinetic theory by Lin et al., J. Fluid Mech. 669,\n167 (2011) developed for 'squirmers' to the bacterial case to quantitatively\npredict enhanced diffusivity of tracer particles in dilute two- and\nthree-dimensional suspensions of swimming bacteria. We demonstrate that the\neffective diffusion coefficient is a product of the bacterial number density,\ntheir swimming speed, a geometric factor characterising the velocity field\ncreated by a single bacterium, and a numerical factor. We show that the\nnumerical factor is, in fact, a rather strong function of the system\nparameters, most notably the run length of the bacteria, and that these\ndependencies have to be taken into account to quantitatively predict the\nenhanced diffusivity. We perform molecular-dynamics-type simulations to confirm\nthe conclusions of the kinetic theory. Our results are in a good agreement with\nthe values of enhanced diffusivity measured in recent two- and\nthree-dimensional experiments.",
        "positive": "The Saffman-Taylor problem on a sphere: The Saffman-Taylor problem addresses the morphological instability of an\ninterface separating two immiscible, viscous fluids when they move in a narrow\ngap between two flat parallel plates (Hele-Shaw cell). In this work, we extend\nthe classic Saffman-Taylor situation, by considering the flow between two\ncurved, closely spaced, concentric spheres (spherical Hele-Shaw cell). We\nderive the mode-coupling differential equation for the interface perturbation\namplitudes and study both linear and nonlinear flow regimes. The effect of the\nspherical cell (positive) spatial curvature on the shape of the interfacial\npatterns is investigated. We show that stability properties of the fluid-fluid\ninterface are sensitive to the curvature of the surface. In particular, it is\nfound that positive spatial curvature inhibits finger tip-splitting. Hele-Shaw\nflow on weakly negative, curved surfaces is briefly discussed."
    },
    {
        "anchor": "Soft lubrication: We consider some basic principles of fluid-induced lubrication at soft\ninterfaces. In particular, we show how the presence of a soft substrate leads\nto an increase in the physical separation between surfaces sliding past each\nother. By considering the model problem of a symmetric non-conforming contact\nmoving tangentially to a thin elastic layer, we determine the normal force in\nthe small and large deflection limit, and show that there is an optimal\ncombination of material and geometric properties which maximizes the normal\nforce. Our results can be generalized to a variety of other geometries which\nshow the same qualitative behavior. Thus they are relevant in the\nelastohydrodynamic lubrication of soft elastic and poroelastic gels and shells,\nand in the context of bio-lubrication in cartilaginous joints.",
        "positive": "Triple minima in free energy of semiflexible polymers: We study the free energy of the worm-like-chain model, in the\nconstant-extension ensemble, as a function of the stiffness for finite chains\nof length L. We find that the polymer properties obtained in this ensemble are\n\"qualitatively\" different from those obtained using constant-force ensembles.\nIn particular we find that as we change the stiffness parameter, the polymer\nmakes a transition from the flexible to the rigid phase and there is an\nintermediate regime of parameter values where the free energy has three minima\nand both phases are stable. This leads to interesting features in the\nforce-extension curves."
    },
    {
        "anchor": "Field theory of structured liquid dielectrics: We develop of a field-theoretic approach for the treatment of both the\nnon-local and the non-linear response of structured liquid dielectrics. Our\nsystems of interest are composed of dipolar solvent molecules and simple salt\ncations and anions. We describe them by two independent order parameters, the\npolarization field for the solvent and the charge density field for the ions,\nincluding and treating the non-electrostatic part of the interactions\nexplicitly and consistently. We show how to derive functionals for the\npolarization and the electrostatic field of increasingly finer scales and solve\nthe resulting mean-field saddle-point equations in the linear regime. We derive\ncriteria for the character of their solutions that depend on the structural\nlengths and the polarity of the solvent. Our approach provides a systematic way\nto derive generalized polarization theories.",
        "positive": "The nature of the phase transition in dipolar fluids: Monte Carlo computer simulations of a quasi two dimensional (2D) dipolar\nfluid at low and intermediate densities indicate that the structure of the\nfluid is well described by an ideal mixture of self-assembling clusters. A\ndetailed analysis of the topology of the clusters, of their internal energy and\nof their size (or mass) distributions further suggests that the system\nundergoes a phase transition from a dilute phase characterized by a number of\ndisconnected clusters to a condensed phase characterized by a network or\nspanning (macroscopic) cluster that includes most of the particles in the\nsystem."
    },
    {
        "anchor": "Topology and complexity of the hydrogen bond network in classical models\n  of water: Over the years, plenty of classical interaction potentials for water have\nbeen developed and tested against structural, dynamical and thermodynamic\nproperties. On the other hands, it has been recently observed (F. Martelli et.\nal, \\textit{ACS Nano}, \\textbf{14}, 8616--8623, 2020) that the topology of the\nhydrogen bond network (HBN) is a very sensitive measure that should be\nconsidered when developing new interaction potentials. Here we report a\nthorough comparison of 11 popular non polarizable classical water models\nagainst their HBN, which is at the root of water properties. We probe the\ntopology of the HBN using the ring statistics and we evaluate the quality of\nthe network inspecting the percentage of broken and intact HBs. For each water\nmodel, we assess the tendency to develop hexagonal rings (that promote\ncrystallization at low temperatures) and pentagonal rings (known to frustrate\nagainst crystallization at low temperatures). We then introduce the\n\\emph{network complexity index}, a general descriptor to quantify how much the\ntopology of a given network deviates from that of the ground state, namely of\nhexagonal or cubic ice. Remarkably, we find that the network complexity index\nallows us to relate, for the first time, the dynamical properties of different\nwater models with their underlying topology of the HBN. Our study provides a\nbenchmark against which the performances of new models should be tested\nagainst, and introduces a general way to quantify the complexity of a network\nwhich can be transferred to other materials and that links the topology of the\nHBN with dynamical properties. Finally, our study introduces a new perspective\nthat can help in rationalizing the transformations among the different phases\nof water and of other materials.",
        "positive": "Conduction in jammed systems of tetrahedra: Control of transport processes in composite microstructures is critical to\nthe development of high performance functional materials for a variety of\nenergy storage applications. The fundamental process of conduction and its\ncontrol through the manipulation of granular composite attributes (e.g., grain\nshape) are the subject of this work. We show that athermally jammed packings of\ntetrahedra with ultra-short range order exhibit fundamentally different\npathways for conduction than those in dense sphere packings. Highly resistive\ngranular constrictions and few face-face contacts between grains result in\nshort-range distortions from the mean temperature field. As a consequence,\n'granular' or differential effective medium theory predicts the conductivity of\nthis media within 10% at the jamming point; in contrast, strong enhancement of\ntransport near interparticle contacts in packed-sphere composites results in\nconductivity divergence at the jamming onset. The results are expected to be\nparticularly relevant to the development of nanomaterials, where nanoparticle\nbuilding blocks can exhibit a variety of faceted shapes."
    },
    {
        "anchor": "Bose-Einstein condensation and superfluidity of dilute Bose gas in a\n  random potential: We develop the dilute Bose gas model with random potential in order to\nunderstand the Bose system in random media such as 4He in porous glass. Using\nthe random potential taking account of the pore size dependence, we can compare\nquantitatively the calculated specific heat with the experimental results,\nwithout free parameters. The agreement is excellent at low temperatures, which\njustifies our model. The relation between Bose condensation and superfluidity\nis discussed. Our model can predict some unobserved phenomena in this system.",
        "positive": "Out-of-equilibrium versus dynamical and thermodynamical transitions for\n  a model protein: Equilibrium and out-of-equilibrium transitions of an off-lattice protein\nmodel have been identified and studied. In particular, the out-of-equilibrium\ndynamics of the protein undergoing mechanical unfolding is investigated, and by\nusing a work fluctuation relation, the system free energy landscape is\nevaluated. Three different structural transitions are identified along the\nunfolding pathways. Furthermore, the reconstruction of the the free and\npotential energy profiles in terms of inherent structure formalism allows us to\nput in direct correspondence these transitions with the equilibrium thermal\ntransitions relevant for protein folding/unfolding. Through the study of the\nfluctuations of the protein structure at different temperatures, we identify\nthe dynamical transitions, related to configurational rearrangements of the\nprotein, which are precursors of the thermal transitions."
    },
    {
        "anchor": "Measuring internal forces in single-stranded DNA: Application to a DNA\n  force clamp: We present a new method for calculating internal forces in DNA structures\nusing coarse-grained models and demonstrate its utility with the oxDNA model.\nThe instantaneous forces on individual nucleotides are explored and related to\nmodel potentials, and using our framework, internal forces are calculated for\ntwo simple DNA systems and for a recently-published nanoscopic force clamp. Our\nresults highlight some pitfalls associated with conventional methods for\nestimating internal forces, which are based on elastic polymer models, and\nemphasise the importance of carefully considering secondary structure and ionic\nconditions when modelling the elastic behaviour of single-stranded DNA. Beyond\nits relevance to the DNA nanotechnological community, we expect our approach to\nbe broadly applicable to calculations of internal force in a variety of\nstructures -- from DNA to protein -- and across other coarse-grained simulation\nmodels.",
        "positive": "Modelling Micropipette Aspiration with Active Particles: The study of cells' dynamical properties is essential to a better\nunderstanding of several physiological processes. These properties are directly\nassociated with cells' mechanical parameters experimentally achieved through\nphysical stress. The micropipette aspiration essay has proven an accurate and\ncontrollable tool to apply physical stress to the cell. In this work, we\nexplore the numerical modeling of two-dimensional cells using an active\nmulti-particle ring submitted to micropipette aspiration. We correlate\nsimulation parameters with experimental data and obtain a complete map of the\ninput parameters and the resulting elastic parameters that could be measured in\nexperiments."
    },
    {
        "anchor": "Steady states of two-dimensional granular systems are unique, stable,\n  and sometimes satisfy detailed balance: Understanding the structural evolution of granular systems is a long-standing\nproblem. A recently proposed theory for such dynamics in two dimensions\npredicts that steady states of very dense systems satisfy detailed-balance. We\nanalyse analytically and numerically the steady states of this theory in\nsystems of arbitrary density and report the following. 1. We discover that all\nsuch dynamics almost certainly possess only one physical steady state, which\nmay or may not satisfy detailed balance. 2. We show rigorously that, if a\ndetailed balance solution is possible then it is unique. The above two results\ncorrect an erroneous conjecture in the literature. 3. We show rigorously that\nthe detailed-balance solutions in very dense systems are globally stable,\nextending the local stability found for these solutions in the literature. 4.\nIn view of recent experimental observations of robust detailed balance steady\nstates in very dilute cyclically sheared systems, our results point to a\nself-organisation of process rates in dynamic granular systems.",
        "positive": "Elastic building blocks for confined sheets: We study the behavior of thin elastic sheets that are bent and strained under\nthe influence of weak, smooth confinement. We show that the emerging shapes\nexhibit the coexistence of two types of domains that differ in their\ncharacteristic stress distributions and energies, and reflect different\nconstraints. A focused-stress patch is subject to a geometric,\npiecewise-inextensibility constraint, whereas a diffuse-stress region is\ncharacterized by a mechanical constraint - the dominance of a single component\nof the stress tensor. We discuss the implications of our findings for the\nanalysis of elastic sheets that are subject to various types of forcing."
    },
    {
        "anchor": "Hydrodynamic Theory of Granular Solids: Permanent, Transient and\n  Granular Elasticity: Although fully elastic when static, granular media become transiently elastic\nwhen being slowly sheared -- during which both the elastic energy and stress\nrelax. Starting from this observation, we cogently derive the framework for\ngranular hydrodynamics, a set of differential equations consistent with general\nprinciples of physics, especially reversible and irreversible thermodynamics.\nIn addition, an expression for the granular elastic energy is reviewed and\nfurther discussed.",
        "positive": "Effects of diffusion coefficients on reversal potentials in ionic\n  channels: In this work, the dependence of reversal potentials and zero-current fluxes\non diffusion coefficients are examined for ionic flows through membrane\nchannels. The study is conducted for the setup of a simple structure defined by\nthe profile of permanent charges with two mobile ion species, one positively\ncharged (cation) and one negatively charged (anion). Numerical observations are\nobtained from analytical results established using geometric singular\nperturbation analysis of classical Poisson-Nernst-Planck models. For 1:1 ionic\nmixtures with arbitrary diffusion coefficients, Mofidi and Liu\n[arXiv:1909.01192] conducted a rigorous mathematical analysis and derived an\nequation for reversal potentials that, in its particular case, can be compared\nto Goldman-Hodgkin-Katz equation. We summarize and extend these results with\nnumerical observations for biological relevant situations. The numerical\ninvestigations on profiles of the electrochemical potentials, ion\nconcentrations, and electrical potential across ion channels are also presented\nfor the zero-current case. Moreover, the behavior of current and fluxes with\nrespect to voltages and permanent charges are investigated. In the opinion of\nthe authors, many results in the paper are not intuitive, and it is difficult,\nif not impossible, to see all cases without investigations of this type."
    },
    {
        "anchor": "Electrostatic correlations in inhomogeneous charged fluids beyond loop\n  expansion: Electrostatic correlation effects in inhomogeneous symmetric electrolytes are\ninvestigated within a previously developed electrostatic self-consistent (SC)\ntheory (R.R. Netz and H. Orland, Eur. Phys.J. E 11, 301 (2003)). To this aim,\nwe introduce two computational approaches that allow to solve the SC equations\nbeyond the loop expansion. Both approaches can handle the case of\ndielectrically discontinuous boundaries where the one-loop theory is known to\nfail. By comparing the theoretical results obtained from these schemes with the\nresults of the MC simulations that we ran for ions at neutral single dielectric\ninterfaces as well as with previous MC data for charged interfaces, we first\nshow that the weak coupling (WC) Debye-Huckel (DH) theory remains\nquantitatively accurate up to the bulk ion density rhob=0.01 M, whereas the SC\ntheory exhibits a good quantitative accuracy up to rhob=0.2 M. Then, we derive\nfrom the perturbative SC scheme the one-loop theory of asymmetrically\npartitioned salt systems around a dielectrically homogeneous charged surface.\nIt is shown that correlation effects originate in these systems from a\ncompetition between the salt screening loss at the interface driving the ions\nto the bulk region, and the interfacial counterion screening excess attracting\nthem towards the surface. In the case of weak surface charges, the interfacial\nsalt screening loss is the dominant effect. As a result, correlations decrease\nthe MF density of both coions and counterions. With increasing surface charge,\nthe surface-attractive counterion screening excess starts to dominate, and\ncorrelation effects amplify in this regime the MF density of both type of ions.\nWe also show that at a characteristic value of the electrostatic coupling\nparameter, electrostatic correlations result in a charge inversion effect.",
        "positive": "Avidity and surface mobility in multivalent ligand-receptor binding: Targeted drug delivery relies on two physical processes: the selective\nbinding of a therapeutic particle to receptors on a specific cell membrane,\nfollowed by transport of the particle across the membrane. In this article, we\naddress some of the challenges in controlling the thermodynamics and dynamics\nof these two processes by combining a simple experimental system with a\nstatistical mechanical model. Specifically, we characterize and model\nmultivalent ligand-receptor binding between colloidal particles and fluid lipid\nbilayers, as well as the surface mobility of membrane-bound particles. We show\nthat the mobility of the receptors within the fluid membrane is key to both the\nthermodynamics and dynamics of binding. First, we find that the\nparticle-membrane binding free energy -- or avidity -- is a strongly nonlinear\nfunction of the ligand-receptor affinity. We attribute the nonlinearity to a\ncombination of multivalency and recruitment of fluid receptors to the binding\nsite. Our results also suggest that partial wrapping of the bound particles by\nthe membrane enhances avidity further. Second, we demonstrate that the lateral\nmobility of membrane-bound particles is also strongly influenced by the\nrecruitment of receptors. Specifically, we find that the lateral diffusion\ncoefficient of a membrane-bound particle is dominated by the hydrodynamic drag\nagainst the aggregate of receptors within the membrane. These results provide\none of the first direct validations of the working theoretical framework for\nmultivalent interactions. They also highlight that the fluidity and elasticity\nof the membrane are as important as the ligand-receptor affinity in determining\nthe binding and transport of small particles attached to membranes."
    },
    {
        "anchor": "Velocity jump in the crack propagation induced on a semi-crystalline\n  polymer sheet by constant-speed stretching: It has long been known for elastomers that the velocity of crack propagation\njumps as a function of strain. On the other hand, such a jump has not been\nreported in the literature for polymers which do not exhibit a rubbery plateau\nin the storage-modulus plot. Here, we report observation of jumps in crack\npropagation for semi-crystalline polymer sheets without the rubbery plateau, as\na result of pulling the sheets at a constant speed. We discuss the advantages\nof this crack-propagation test under constant-speed stretching and provide\nphysical interpretation of the velocity jump observed for non-elastomer sheets\non the basis of a recently proposed theory for the velocity jump in crack\npropagation.",
        "positive": "Information and motility exchange in collectives of active particles: We examine the interplay of motility and information exchange in a model of\nrun-and-tumble active particles where the particle's motility is encoded as a\nbit of information that can be exchanged upon contact according to the rules of\nAND and OR logic gates in a circuit. Motile AND particles become non-motile\nupon contact with a non-motile particle. Conversely, motile OR particles remain\nmotile upon collision with their non-motile counterparts. AND particles that\nhave become non-motile additionally \"reawaken\", i.e., recover their motility,\nat a fixed rate $\\mu$, as in the SIS (Susceptible, Infected, Susceptible) model\nof epidemic spreading, where an infected agent can become healthy again, but\nkeeps no memory of the recent infection, hence it is susceptible to a renewed\ninfection. For $\\mu=0$, both AND and OR particles relax irreversibly to\nabsorbing states of all non-motile or all motile particles, respectively. The\nrelaxation kinetics is, however, faster for OR particles that remain active\nthroughout the process. At finite $\\mu$, the AND dynamics is controlled by the\ninterplay between reawakening and collision rates. The system evolves to a\nstate of all motile particles (an absorbing state in the language of absorbing\nphase transitions) for $\\mu>\\mu_c$ and to a mixed state with coexisting motile\nand non-motile particles (an active state in the language of absorbing phase\ntransitions) for $\\mu<\\mu_c$. The final state exhibits a rich structure\ncontrolled by motility-induced aggregation. Our work can be relevant to\nbiochemical signaling in motile bacteria, the spreading of epidemics and of\nsocial consensus, as well as light-controlled organization of active colloids."
    },
    {
        "anchor": "Structural quantities of quasi-two-dimensional fluids: Quasi-two-dimensional fluids can be generated by confining a fluid between\ntwo parallel walls with narrow separation. Such fluids exhibit an inhomogeneous\nstructure perpendicular to the walls due to the loss of translational symmetry.\nTaking the transversal degrees of freedom as a perturbation to an appropriate\n2D reference fluid we provide a systematic expansion of the $m$-particle\ndensity for arbitrary $m$. To leading order in the slit width this density\nfactorizes into the densities of the transversal and lateral degrees of\nfreedom. Explicit expressions for the next-to-leading order terms are\nelaborated analytically quantifying the onset of inhomogeneity. The case $m=1$\nyields the density profile with a curvature given by an integral over the\npair-distribution function of the corresponding 2D reference fluid, which\nreduces to its 2D contact value in the case of pure excluded-volume\ninteractions. Interestingly, we find that the 2D limit is subtle and requires\nstringent conditions on the fluid-wall interactions. We quantify the rapidity\nof convergence for various structural quantities to their 2D counterparts.",
        "positive": "Topological phonons and Weyl lines in 3 dimensions: Topological mechanics and phononics have recently emerged as an exciting\nfield of study. Here we introduce and study generalizations of the\nthree-dimensional pyrochlore lattice that have topologically protected edge\nstates and Weyl lines in their bulk phonon spectra, which lead to zero surface\nmodes that flip from one edge to the opposite as a function of surface\nwavenumber."
    },
    {
        "anchor": "Role of charge regulation and flow slip on the ionic conductance of\n  nanopores: an analytical approach: The number of precise conductance measurements in nanopores is quickly\ngrowing. In order to clarify the dominant mechanisms at play and facilitate the\ncharacterization of such systems for which there is still no clear consensus,\nwe propose an analytical approach to the ionic conductance in nanopores that\ntakes into account (i) electro-osmotic effects, (ii) flow slip at the pore\nsurface for hydrophobic nanopores, (iii) a component of the surface charge\ndensity that is modulated by the reservoir $p$H and salt concentration $c_s$\nusing a simple charge regulation model, and (iv) a fixed surface charge density\nthat is unaffected by $p$H and $c_s$. Limiting cases are explored for various\nranges of salt concentration and our formula is used to fit conductance\nexperiments found in the literature for carbon nanotubes. This approach permits\nus to catalog the different possible transport regimes and propose an\nexplanation for the wide variety of currently known experimental behavior for\nthe conductance versus $c_s$.",
        "positive": "Entropy-driven formation of prolate and oblate cholesteric phases by\n  computer simulations: Predicting the macroscopic chiral behaviour of cholesteric liquid crystals\nfrom the microscopic chirality of the particles is highly non-trivial, even\nwhen the chiral interactions are purely entropic in nature. Here we introduce a\nnovel chiral hard-particle model, namely particles with a twisted polyhedral\nshape and obtain, for the first time, a stable fully-entropy-driven cholesteric\nphase by computer simulations. By slightly modifying the triangular base of the\nparticle, we are able to switch from a left-handed prolate to a right-handed\noblate cholesteric using the same right-handed twisted particle model.\nFurthermore, we find qualitative agreement with an Onsager-like theory,\nsuggesting that the latter can be used as a quick tool to scan the huge\nparameter space associated to the microscopic chirality. Our results unveil how\nthe competition between particle biaxiality and chirality is reflected into the\nnematic self-organization and new theoretical challenges on the self-assembly\nof chiral particles can be undertaken."
    },
    {
        "anchor": "Multiple transient memories in sheared suspensions: robustness,\n  structure, and routes to plasticity: Multiple transient memories, originally discovered in charge-density-wave\nconductors, are a remarkable and initially counterintuitive example of how a\nsystem can store information about its driving. In this class of memories, a\nsystem can learn multiple driving inputs, nearly all of which are eventually\nforgotten despite their continual input. If sufficient noise is present, the\nsystem regains plasticity so that it can continue to learn new memories\nindefinitely. Recently, Keim & Nagel showed how multiple transient memories\ncould be generalized to a generic driven disordered system with noise, giving\nas an example simulations of a simple model of a sheared non-Brownian\nsuspension. Here, we further explore simulation models of suspensions under\ncyclic shear, focussing on three main themes: robustness, structure, and\noverdriving. We show that multiple transient memories are a robust feature\nindependent of many details of the model. The steady-state spatial distribution\nof the particles is sensitive to the driving algorithm; nonetheless, the memory\nformation is independent of such a change in particle correlations. Finally, we\ndemonstrate that overdriving provides another means for controlling memory\nformation and retention.",
        "positive": "Embedding Orthogonal Memories in a Colloidal Gel through Oscillatory\n  Shear: It has recently been shown that in a broad class of disordered systems\noscillatory shear training can embed memories of specific shear protocols in\nrelevant physical parameters such as the yield strain. These shear protocols\ncan be used to change the physical properties of the system and memories of the\nprotocol can later be \"read\" out. Here we investigate shear training memories\nin colloidal gels, which include an attractive interaction and network\nstructure, and discover that such systems can support memories both along and\northogonal to the training flow direction. We use oscillatory shear protocols\nto set and read out the yield strain memories and confocal microscopy to\nanalyze the rearranging gel structure throughout the shear training. We find\nthat the gel bonds remain largely isotropic in the shear-vorticity plane\nthroughout the training suggesting that structures formed to support shear\nalong the training shear plane are also able to support shear along the\northogonal plane. Orthogonal memory extends the usefulness of shear memories to\nmore applications and should apply to many other disordered systems as well."
    },
    {
        "anchor": "Tkachenko oscillations and the compressibility of a rotating Bose gas: The elastic oscillations of the vortex lattice of a cold Bose gas (Tkachenko\nmodes) are shown to play a crucial role in the saturation of the\ncompressibility sum rule, as a consequence of the hybridization with the\nlongitudinal degrees of freedom. The presence of the vortex lattice is\nresponsible for a $q^2$ behavior of the static structure factor at small\nwavevectors $q$, which implies the absence of long range order in 2D\nconfigurations at zero temperature. Sum rules are used to calculate the\nTkachenko frequency in the presence of harmonic trapping. Results are derived\nin the Thomas-Fermi regime and compared with experiments as well as with\nprevious theoretical estimates.",
        "positive": "Electric-field-enhanced transport in polyacrylamide hydrogel\n  nano-composites: Electroosmotic pumping through uncharged hydrogels can be achieved by\nembedding the polymer network with charged colloidal inclusions. Matos and\nco-workers (2006) recently used the concept to enhance the diffusion-limited\nflux of uncharged molecules across polyacrylamide hydrogel membraness for the\npurpose of improving the performance of biosensors. This paper seeks to link\ntheir reported macroscale diagnostics to physicochemical characteristics of the\ncomposite microstructure. A mathematical model for the bulk electroosmotically\nenhanced tracer flux is proposed, which is combined with the electrokinetic\nmodel to ascertain the electroosmotic pumping velocity from measured flux\nenhancements. Because the experiments are performed with a known current\ndensity, but unknown bulk conductivity and electric field strength, theoretical\nestimates of the bulk electrical conductivity are adopted. These account for\nnano-particle polarization, added counterions, and non-specific adsorption.\nTheoretical predictions of the flux enhancement, achieved without any fitting\nparameters, are within a factor of two of the experiments. Alternatively, if\nthe Brinkman screening length of the polymer skeleton is treated as a fitting\nparameter, then the best-fit values are bounded by the range 0.9-1.6 nm,\ndepending on the inclusion size and volume fraction. Independent\npressure-driven flow experiments reported in the literature for polyacrylamide\ngels without inclusions suggest 0.4 or 0.8 nm. The comparison can be improved\nby allowing for hindered ion migration, while uncertainties regarding the\ninclusion surface charge are demonstrated to have a negligible influence on the\nelectroosmotic flow."
    },
    {
        "anchor": "Dynamics of suspended rigid aggregating particles in flowing medium:\n  theory, analysis and scientific computing: We develop and present a unified multi-scale model (involving three scales of\nspatial organisation) to study the dynamics of rigid aggregating particles\nsuspended in a viscous fluid medium and subject to a steady poiseuille flow. At\nmicro-level, the theory of adhesion describing the attachment / detachment\nkinetics of two rigid spheres coated with binding ligands, is utilized to\ndescribe the collision frequency function. The meso-scale dynamics is outlined\nthrough a continuous general dynamic equation governing the time rate of change\nof the particle size distribution function. The micro-meso coupling is achieved\nvia the balancing of the mesoscale drag forces and couples with the micro-scale\nforces associated with the binder kinetics. Inside the macro domain (i.e., a\nlong pipe), the model is equation free and divided into equal sized patches.\nThe macroscale solution within each patch is obtained via appropriate\n(extrapolatory) coupling and amplitude conditions.",
        "positive": "Elasticity of an interfacial particle raft: We study the collective behaviour of a close packed monolayer of non-Brownian\nparticles at a fluid-liquid interface. Such a particle raft forms a\ntwo-dimensional elastic solid and can support anisotropic stresses and strains,\ne.g. it buckles in uniaxial compression and cracks in tension. We characterise\nthis solid in terms of a Young's modulus and Poisson ratio derived from simple\ntheoretical considerations and show the validity of these estimates by using an\nexperimental buckling assay to deduce the Young's modulus."
    },
    {
        "anchor": "Heterogeneous structure and dynamics of water in a hydrated collagen\n  microfibril: Collagen, type I in particular, is the protein of choice by Nature to design\nstructural materials. Its hierarchical fibrillar structure confers to collagen\nits outstanding mechanical properties. Nonetheless, fibrillar collagen may\nrather be viewed as a composite material made of protein, macromolecules (such\nas glycosaminoglycans and proteoglycans) and water. Yet, the properties of\nwater and the fine interactions of water with the protein constituent of these\nnanocomposites have only received limited attention. Here, we propose to\ninvestigate in-depth water structure and dynamics confined within the\nmicrofibril crystal structure of collagen type I to establish its impact on the\nproperties of collagen. We found that the properties of water vary strongly\nwith the level of hydration of the crystal, and spatially along the long axis\nof the crystal, namely moving from the so-called gap region to the so-called\noverlap region. In short, at low hydration, water acts as a glue between\nprotein chains; while at high hydration, water acts as a lubricant. Beyond\nself-assembly and properties of fibrillar collagen, such heterogeneous\nstructure and anisotropic dynamics may control its biomineralization and the\nproperties of biological tissues such as bone.",
        "positive": "Modelling the Mechanics and Hydrodynamics of Swimming E. coli: The swimming properties of an E. coli-type model bacterium are investigated\nby mesoscale hy- drodynamic simulations, combining molecular dynamics\nsimulations of the bacterium with the multiparticle particle collision dynamics\nmethod for the embedding fluid. The bacterium is com- posed of a\nspherocylindrical body with attached helical flagella, built up from discrete\nparticles for an efficient coupling with the fluid. We measure the hydrodynamic\nfriction coefficients of the bacterium and find quantitative agreement with\nexperimental results of swimming E. coli. The flow field of the bacterium shows\na force-dipole-like pattern in the swimming plane and two vor- tices\nperpendicular to its swimming direction arising from counterrotation of the\ncell body and the flagella. By comparison with the flow field of a force dipole\nand rotlet dipole, we extract the force- dipole and rotlet-dipole strengths for\nthe bacterium and find that counterrotation of the cell body and the flagella\nis essential for describing the near-field hydrodynamics of the bacterium."
    },
    {
        "anchor": "Granular gravitational collapse and chute flow: Inelastic grains in a flow under gravitation tend to collapse into states in\nwhich the relative normal velocities of two neighboring grains is zero. If the\ntime scale for this gravitational collapse is shorter than inverse strain rates\nin the flow, we propose that this collapse will lead to the formation of\n``granular eddies\", large scale condensed structures of particles moving\ncoherently with one another. The scale of these eddies is determined by the\ngradient of the strain rate. Applying these concepts to chute flow of granular\nmedia, (gravitationally driven flow down inclined planes) we predict the\nexistence of a bulk flow region whose rheology is determined only by flow\ndensity. This theory yields the experimental ``Pouliquen flow rule\",\ncorrelating different chute flows; it also correctly accounts for the different\nflow regimes observed.",
        "positive": "A charge dependent long-ranged force drives tailored assembly of matter\n  in solution: The interaction between charged objects in solution is generally expected to\nrecapitulate two central principles of electromagnetics: (i) like-charged\nobjects repel, and (ii) they do so regardless of the sign of their electrical\ncharge. Here we demonstrate experimentally that the solvent plays a hitherto\nunforeseen but crucial role in interparticle interactions, and importantly,\nthat interactions in the fluid phase can break charge-reversal symmetry. We\nshow that in aqueous solution, negatively charged particles can attract at long\nrange while positively charged particles repel. In solvents that exhibit an\ninversion of the net molecular dipole at an interface, such as alcohols, we\nfind that the converse can be true: positively charged particles may attract\nwhereas negatives repel. The observations hold across a wide variety of surface\nchemistries: from inorganic silica and polymeric particles to polyelectrolyte-\nand polypeptide-coated surfaces in aqueous solution. A theory of interparticle\ninteractions that invokes solvation at an interface explains the observations.\nOur study establishes a specific and unanticipated mechanism by which the\nmolecular solvent may give rise to a strong and long-ranged force in solution,\nwith immediate ramifications for a variety of particulate and molecular\nprocesses including tailored self-assembly, gelation and crystallization, as\nwell as biomolecular condensation, coacervation and phase segregation. These\nfindings also shed light on the solvent-induced interfacial electrical\npotential - an elusive quantity in electrochemistry and interface science\nimplicated in many natural and technological processes, such as atmospheric\nchemical reactions, electrochemical energy storage and conversion, and the\nconduction of ions across cell membranes."
    },
    {
        "anchor": "Viscous force exerted on a foam at a solid boundary : influence of the\n  liquid fraction and of the bubble size: We study experimentally the pressure drop needed to push a bubble train in a\nmillimetric channel, as a function of the velocity. For dry liquid foams, the\ninfluence of the amount of liquid and of the bubble size is pointed out and we\npredict theoretically that this influence is closely related to the power law\nobtained for the force/velocity relation. This model is in fair agreement with\nour experimental data and provides a new interpretation of previous results.",
        "positive": "Stress Relaxation of Near-Critical Gels: The time-dependent stress relaxation for a Rouse model of a crosslinked\npolymer melt is completely determined by the spectrum of eigenvalues of the\nconnectivity matrix. The latter has been computed analytically for a mean-field\ndistribution of crosslinks. It shows a Lifshitz tail for small eigenvalues and\nall concentrations below the percolation threshold, giving rise to a stretched\nexponential decay of the stress relaxation function in the sol phase. At the\ncritical point the density of states is finite for small eigenvalues, resulting\nin a logarithmic divergence of the viscosity and an algebraic decay of the\nstress relaxation function. Numerical diagonalization of the connectivity\nmatrix supports the analytical findings and has furthermore been applied to\ncluster statistics corresponding to random bond percolation in two and three\ndimensions."
    },
    {
        "anchor": "Active particles with delayed attractions form quaking crystallites: Perception-reaction delays have experimentally been found to cause a\nspontaneous circling of microswimmers around a targeted center. Here we\ninvestigate the many-body version of this experiment with Brownian-dynamics\nsimulations of active particles in a plane. For short delays, the soft\nspherical discs form a hexagonal colloidal crystallite around a fixed target\nparticle. Upon increasing the delay time, we observe a bifurcation to a chiral\ndynamical state that we can map onto that found for a single active particle.\nThe different angular velocities at different distances from the target induce\nshear stresses that grow with increasing delay. As a result, tangential and,\nlater, also radial shear bands intermittently break the rotating crystallite.\nEventually, for long delays, the discs detach from the target particle to\ncircle around it near the preferred single-particle orbit, while spinning and\ntrembling from tidal quakes",
        "positive": "Wetting dynamics by mixtures of fast and slow self-propelled particles: We study active surface wetting using a minimal model of bacteria that takes\ninto account the intrinsic motility diversity of living matter. A mixture of\n\"fast\" and \"slow\" self-propelled Brownian particles is considered in the\npresence of a wall. The evolution of the wetting layer thickness shows an\novershoot before stationarity and its composition evolves in two stages,\nequilibrating after a slow elimination of excess particles. Non-monotonic\nevolutions are shown to arise from delayed avalanches towards the dilute phase\ncombined with the emergence of a transient particle front."
    },
    {
        "anchor": "The Formation of Ultra-Stable Glasses via Precipitation: a Modelling\n  Study: The precipitation of a glass forming solute from solution is modelled using a\nlattice model previously introduced to study dissolution kinetics of amorphous\nmaterials. The model includes the enhancement of kinetics at the surface of a\nglass in contact with a plasticizing solvent. We demonstrate that precipitation\ncan produce a glass substantially more stable than that produced by very long\ntime annealing of the bulk glass former. The energy of these ultra-stable\namorphous precipitates is found to be dominated by residual solvent rather than\nhigh energy glass configurations.",
        "positive": "Disk wrinkling under gravity: We study the deflection by gravity of a circular elastic disk deposited on a\nrigid support. The axisymmetric deflection induces a compressive orthoradial\nstresses which leads to a wrinkling instability above a critical threshold of\nthe dimensionless gravity force. We study this instability by a combination of\nexperiments, numerical simulations and analytical tools, with a particular\nfocus on the role of geometry. We show that aspect ratio is a crucial parameter\nthat controls both the threshold of instability and the most unstable mode. The\ninfluence of this parameter on the threshold can be catched by introducing a\nnew nondimensionalization of the transverse load."
    },
    {
        "anchor": "Thermally driven elastic membranes are quasi-linear across all scales: We study the static and dynamic structure of thermally fluctuating elastic\nthin sheets by investigating the overdamped dynamic F\\\"oppl-von K\\'arm\\'an\nequation, in which the F\\\"oppl-von K\\'arm\\'an equation from elasticity theory\nis driven by white noise. This nonlinear equation is governed by a single\nnondimensional coupling parameter $g$ whose large and small values correspond\nto weak and strong nonlinear coupling respectively. By analysing the weak\ncoupling case with ordinary perturbation theory and the strong coupling case\nwith a self-consistent methodology known as the self-consistent expansion,\nprecise analytic predictions for the static and dynamic structure factors are\nobtained. The maximum frequency $n_{\\max}$ supported by the system plays a role\nin determining which of three possible classes such sheets belong to: (1) when\n$g\\gg1$, the system is mostly linear with roughness exponent $\\zeta=1$ and\ndynamic exponent $z=4$, (2) when $g\\ll2/n_{\\max}$, the system is extremely\nnonlinear with roughness exponent $\\zeta=1/2$ and dynamic exponent $z=3$, (3)\nbetween these regimes, an intermediate behaviour is obtained in which a\ncrossover occurs such that the nonlinear behaviour is observed for small\nfrequencies while the linear behaviour is observed for large frequencies. The\nlarge frequency linear tail is found to have a significant impact on the small\nfrequency behaviour of the sheet. Back-of-the-envelope calculations suggest\nthat ultra-thin materials such as graphene lie in this intermediate regime.\nDespite the existence of these three distinct behaviours, the decay rate of the\ndynamic structure factor is related to the static structure factor as if the\nsystem were completely linear. This quasi-linearity occurs regardless of the\nsize of $g$ and at all length scales. Numerical simulations confirm the\nexistence of the three classes of behaviour and the quasi-linearity of all\nclasses.",
        "positive": "Solid - Liquid Phase Transition in a Gibbs Monolayer of Melissic Acid at\n  the n-Hexane - Water Interface: A sharp phase transition from a crystalline state with the area per molecule\nA = (17 +/- 1) Angstrom^2 to a liquid state with A = (23 +/- 1) Angstrom^2 at\nthe n-hexane - water interface in a Gibbs monolayer of melissic acid has been\nrevealed in data of X-ray reflectometry with the use of synchrotron radiation."
    },
    {
        "anchor": "Shaping nanoparticle fingerprints at the interface of cholesteric\n  droplets: The ordering of nanoparticles into predetermined configurations is of\nimportance to the design of advanced technologies. In this work, we moderate\nthe surface anchoring against the bulk elasticity of liquid crystals to\ndynamically shape nanoparticle assemblies at a fluid interface. By tuning the\ndegree of nanoparticle hydrophobicity with surfactants that alter the molecular\nanchoring of liquid crystals, we pattern nanoparticles at the interface of\ncholesteric liquid crystal emulsions. Adjusting the particle hydrophobicity\nmore finely further modifies the rigidity of assemblies. We establish that\npatterns are tunable by varying both surfactant and chiral dopant\nconcentrations. Since particle assembly occurs at the interface with the\ndesired structures exposed to the surrounding phase, we demonstrate that\nparticles can be readily crosslinked and manipulated, forming structures that\nretain their shape under external perturbations. This study establishes the\ntemplating of nanomaterials into reconfigurable arrangements. Interfacial\nassembly is tempered by elastic patterns that arise from the geometric\nfrustration of confined cholesterics. This work serves as a basis for creating\nmaterials with chemical heterogeneity and with linear, periodic structures,\nessential for optical and energy applications.",
        "positive": "Analytical derivation of lateral pressure profile from microscopic model\n  of lipid bilayer: Field-theoretical method is proposed, that yields analytical expression for\nlateral pressure distribution across hydrophobic core of a bilayer lipid\nmembrane. Lipid molecule, repelling entropicaly surrounding neighbors, is\nmodeled as a flexible string embedded between confining walls in the\nself-consistent harmonic potential. At room temperature the pressure profile is\nexpressed solely via lowest energy eigenfunctions of the operator of the string\nenergy density. Analytical results compare favorably with molecular dynamics\nsimulations. The theory is suited to study protein-lipid interaction."
    },
    {
        "anchor": "A reduction-to-absurdity approach using absolutely smooth solid surfaces\n  to unveil the origins of wetting: Contact angle hysteresis and generation of dynamics angle are two fundamental\nphenomena about the contact angle deviation from the equilibrium state.\nRoughness on the solid surface, disjoining pressure in the thin film, and\nliquid-solid adhesion have all been considered as the origins of the phenomena.\nThis work for the first time made a reduction to absurdity by employing\nabsolutely smooth solid surfaces in ultra-large-scale molecular dynamic\nsimulation. The results showed that the equilibrium angles were well\nestablished on the absolutely smooth surface just as regular, while the\nhysteresis and the dynamic angle vanished. The critical structure of the convex\nnanobending for advancing contact lines vanished as well. In contrast, the\nsolids that made of atoms, even at the minimum roughness, would bring\nsignificant angle deviation and convex nanobending. A 3D observation was\nfurther made using state-of-the-art helium ion microscopy for the first time\nrevealing the ubiquitous nanoscopic distortion along the contact line on\natomically smooth surfaces. The results answer the question of the origin of\nthe angle deviation, that the hysteresis and dynamic angle can be unified to\noriginate from the friction, either static or dynamic; and at the same time\nresolve the puzzle of the hysteresis existence on reported smooth surfaces,\nshowing that even the minimum i.e. atomic roughness is great enough to be\neffective on the contact line. The results are against the disjoining pressure\ntheory which ignored the roughness and predicted the occurrence of the\nhysteresis on absolutely smooth solids.",
        "positive": "Exploring the Relationship Between Softness and Excess Entropy in\n  Glass-forming Systems: We explore the relationship between a machine-learned structural quantity\n(softness) and excess entropy in simulations of supercooled liquids. Excess\nentropy is known to scale well the dynamical properties of liquids, but this\nquasi-universal scaling is known to breakdown in the supercooled and glassy\nregimes. Using numerical simulations, we test whether a local form of the\nexcess entropy can lead to predictions that derive from softness, which has\nbeen shown to correlate well with the tendency for individual particles to\nrearrange. To that end, we explore leveraging softness to compute excess\nentropy in the traditional fashion over softness groupings. Our results show\nthat by computing the excess entropy over softness-binned groupings, we can\nbuild a strong quantitative relationship between the rearrangement barriers\nacross the explored systems."
    },
    {
        "anchor": "Swimming active droplet: A theoretical analysis: Recently, an active microswimmer was constructed where a micron-sized droplet\nof bromine water was placed into a surfactant-laden oil phase. Due to a\nbromination reaction of the surfactant at the interface, the surface tension\nlocally increases and becomes non-uniform. This drives a Marangoni flow which\npropels the squirming droplet forward. We develop a\ndiffusion-advection-reaction equation for the order parameter of the surfactant\nmixture at the droplet interface using a mixing free energy. Numerical\nsolutions reveal a stable swimming regime above a critical Marangoni number M\nbut also stopping and oscillating states when M is increased further. The\nswimming droplet is identified as a pusher whereas in the oscillating state it\noscillates between being a puller and a pusher.",
        "positive": "Glass transitions in two-dimensional suspensions of colloidal ellipsoids: We observed a two-step glass transition in monolayers of colloidal ellipsoids\nby video microscopy. The glass transition in the rotational degree of freedom\nwas at a lower density than that in the translational degree of freedom.\nBetween the two transitions, ellipsoids formed an orientational glass.\nApproaching the respective glass transitions, the rotational and translational\nfastest-moving particles in the supercooled liquid moved cooperatively and\nformed clusters with power-law size distributions. The mean cluster sizes\ndiverge in power law as approaching the glass transitions. The clusters of\ntranslational and rotational fastest-moving ellipsoids formed mainly within\npseudo-nematic domains, and around the domain boundaries, respectively."
    },
    {
        "anchor": "Lamellar Diblock Copolymers on Rough Substrates: Self-consistent Field\n  Theory Studies: We present numerical calculations of lamellar phases of di-block copolymers\n(BCP) confined between two surfaces, where the top surface is flat and the\nbottom one is corrugated. The corrugated substrate is assumed to have a single\n$q$-mode of lateral undulations with a wavenumber q_s and amplitude R. We focus\non the effects of substrate roughness, parameterized by the dimensionless\nquantity, q_sR, on the relative stability between parallel and perpendicular\norientations of the lamellar phase. The competition between film confinement,\nenergy cost of elastic deformation and gain in surface energy induces a\nparallel-to-perpendicular transition of the BCP lamellae. Employing\nself-consistent field theory (SCFT), we study the critical substrate roughness\nvalue corresponding to this transition. The critical value increases as\nfunction of the surface preference towards one of the two BCP components, and\nas function of film thickness. But, it decreases with increasing values of the\nFlory-Huggins parameter. Our findings are equivalent to stating that the\ncritical value decreases as the BCP molecular weight or the natural BCP\nperiodicity increases. We further show that the rough substrate can overcome\nthe formation of parallel lamellae in cases where the top surface has a\npreference towards one of the two BCP components. Our results are in good\nagreement with previous experiments, and highlight the physical conditions\nbehind the perpendicular orientation of lamellar phases, as is desired in\nnanolithography and other industrial applications.",
        "positive": "Order, intermittency and pressure fluctuations in a system of\n  proliferating rods: Non-motile elongated bacteria confined in two-dimensional open micro-channels\ncan exhibit collective motion and form dense monolayers with nematic order if\nthe cells proliferate, i.e., grow and divide. Using soft molecular dynamics\nsimulations of a system of rods interacting through short range mechanical\nforces, we study the effects of the cell growth rate, the cell aspect ratio and\nof the sliding friction on nematic ordering and on pressure fluctuations in\nconfined environments. Our results indicate that rods with aspect ratio >3.0\nreach quasi-perfect nematic states at low sliding friction. At higher\nfrictions, the global nematic order parameter shows intermittent fluctuations\ndue to sudden losses of order and the time intervals between these bursts are\npower-law distributed. The pressure transverse to the channel axis can vary\nabruptly in time and shows hysteresis due to lateral crowding effects. The\nlongitudinal pressure field is on average correlated to nematic order, but it\nis locally very heterogeneous and its distribution follows an inverse\npower-law, in sharp contrast with non-active granular systems. We discuss some\nimplications of these findings for tissue growth."
    },
    {
        "anchor": "Curso introductorio de cristales l\u00edquidos I: fases y propiedades\n  estructurales (Introductory Course on Liquid Crystals I: Phases and\n  Structural Properties): Liquid crystals are the prototype of the so-called soft condensed matter. In\nsimple terms they are \"structured liquids\" that historically have received a\nlot of interest because they help to generate new concepts and knowledge in\nPhysics, and possess important electro--optical applications, e. g., in\ndisplays of mobile computers and telephones. More recently, it has been\ndiscovered that liquid crystals could be applied in fabrication of\nmetamaterials and in biomedicine where they are potentially useful for tissue\nidentification, controlled drug delivery and detection of bacteria and viruses.\nHowever, in Mexico, liquid crystals courses are included only in a few\nundergraduate programs on Physics being elective in most of the cases.\nTherefore, literature for teaching about liquid crystals in Spanish is scarce.\nIn this paper we will discuss about elementary Physics of liquid crystals and\nthe mathematical tools that permit to analyze them. We will explain, mainly,\nhow to analytically characterize the symmetry and order of static uniaxial\nnematic liquid crystals, the most simple of all liquid crystal phases. We will\nconduct this explanation in basic terms, suitable for science and engineering\nstudents at intermediate undergraduate level, with knowledge about linear\nalgebra and vector calculus, willing to approach for the first time to this\nsubject. Our goal is to support the Latin American scientific community in\npreparing human resources in this field. The article is written in Spanish to\ncontribute to the establishment and communication of concepts that only exist\nin other languages in the specialized literature.",
        "positive": "Polarization and Charge Transfer in the Hydration of Chloride Ions: A theoretical study of the structural and electronic properties of the\nchloride ion and water molecules in the first hydration shell is presented. The\ncalculations are performed on an ensemble of configurations obtained from\nmolecular dynamics simulations of a single chloride ion in bulk water. The\nsimulations utilize the polarizable AMOEBA force field for trajectory\ngeneration, and MP2-level calculations are performed to examine the electronic\nstructure properties of the ions and surrounding waters in the external field\nof more distant waters. The ChelpG method is employed to explore the effective\ncharges and dipoles on the chloride ions and first-shell waters. The Quantum\nTheory of Atoms in Molecules (QTAIM) is further utilized to examine charge\ntransfer from the anion to surrounding water molecules.\n  From the QTAIM analysis, 0.2 elementary charges are transferred from the ion\nto the first-shell water molecules. The default AMOEBA model overestimates the\naverage dipole moment magnitude of the ion compared with the estimated quantum\nmechanical value. The average magnitude of the dipole moment of the water\nmolecules in the first shell treated at the MP2 level, with the more distant\nwaters handled with an AMOEBA effective charge model, is 2.67 D. This value is\nclose to the AMOEBA result for first-shell waters (2.72 D) and is slightly\nreduced from the bulk AMOEBA value (2.78 D). The magnitude of the dipole moment\nof the water molecules in the first solvation shell is most strongly affected\nby the local water-water interactions and hydrogen bonds with the second\nsolvation shell, rather than by interactions with the ion."
    },
    {
        "anchor": "Friction of poroelastic contacts with thin hydrogel films: We report on the frictional behaviour of thin poly(dimethylacrylamide) (PDMA)\nhydrogels films grafted on glass substrates in sliding contact with a glass\nspherical probe. Friction experiments are carried out at various velocities and\napplied normal loads with the contact fully immersed in water. In addition to\nfriction force measurements, a novel optical set-up is designed to image the\nshape of the contact under steady-state sliding. The velocity-dependence of\nboth friction force $F_t$ and contact shape is found to be controlled by a\nP\\'eclet number Pe defined as the ratio of the time $\\tau$ needed to drain the\nwater out of the contact region to a contact time $a/v$, where $v$ is the\nsliding velocity and $a$ is the contact radius. When Pe<1, the equilibrium\ncircular contact achieved under static normal indentation remains unchanged\nduring sliding. Conversely, for Pe>1, a decrease in the contact area is\nobserved together with the development of a contact asymmetry when the sliding\nvelocity is increased. A maximum in $F_t$ is also observed at Pe~$\\approx$~1.\nThese experimental observations are discussed in the light of a poroelastic\ncontact model based on a thin film approximation. This model indicates that the\nobserved changes in contact geometry are due to the development of a pore\npressure imbalance when Pe>1. An order of magnitude estimate of the friction\nforce and its dependence on normal load and velocity is also provided under the\nassumption that most of the frictional energy is dissipated by poroelastic flow\nat the leading and trailing edges of the sliding contact.",
        "positive": "Improved general-purpose five-point model for water: TIP5P/2018: A new five point potential for liquid water, TIP5P/2018, is presented along\nwith the techniques used to derive its charges from ab initio per-molecule\nelectrostatic potentials in the liquid phase using the split charge\nequilibration (SQE) of Nistor et al. [J. Chem. Phys. 125, 094108 (2006)]. By\ntaking the density and diffusion dependence on temperature as target\nproperties, significant improvements to the behavior of isothermal\ncompressibility were achieved along with improvements to other thermodynamic\nand rotational properties. While exhibiting a dipole moment close to ab initio\nvalues, TIP5P/2018 suffers from a too small quadrupole moment due to the charge\nassignment procedure and results in an overestimation of the dielectric\nconstant."
    },
    {
        "anchor": "Effects of hydrophobic solute on water normal modes: The vibrational modes of water get significantly modified by external\nsolutes; this becomes particularly important when the solute is hydrophobic. In\nthis work, we examine the effects of a tiny hydrophobe, methane, on the normal\nmodes of water, using small cluster-based harmonic normal mode analysis of\naqueous methane system. We estimate the vibrational density of states and also\nthe infrared spectral density. We compare the methane-water data with the bulk\nwater response. We decompose these modes based on different vibrational\ncharacters. The stretch-bend decomposition reflects a pronounced coupling\nbetween the methane asymmetric stretch mode and the water symmetric stretch\nmode. We examine the methane-water data in terms of the symmetry of the central\nwater molecule's vibrations and find that asymmetric modes do not contribute.\nWe also find that the vibrational modes having non-zero contributions from\nmethane molecule are extremely localized in nature.",
        "positive": "Pressure and Phase Equilibria in Interacting Active Brownian Spheres: We derive from first principles the mechanical pressure $P$, defined as the\nforce per unit area on a bounding wall, in a system of spherical, overdamped,\nactive Brownian particles at density $\\rho$. Our exact result relates $P$, in\nclosed form, to bulk correlators and shows that (i) $P(\\rho)$ is a state\nfunction, independent of the particle-wall interaction; (ii) interactions\ncontribute two terms to $P$, one encoding the slow-down that drives\nmotility-induced phase separation, and the other a direct contribution well\nknown for passive systems; (iii) $P(\\rho)$ is equal in coexisting phases. We\ndiscuss the consequences of these results for the motility-induced phase\nseparation of active Brownian particles, and show that the densities at\ncoexistence do not satisfy a Maxwell construction on $P$."
    },
    {
        "anchor": "High-Acceleration Patterns in Thin Vibrated Granular Layers: Theoretical and experimental study of high-acceleration patterns in vibrated\ngranular layers is presented. The order parameter model based on parametric\nGinzburg-Landau equation is used to describe strongly nonlinear excitations\nincluding hexagons, interface between flat anti-phase domains and new localized\nobjects, super-oscillons. The experiments confirmed the existence of\nsuper-oscillons and bound states of super-oscillons and interfaces. On the\nbasis of order parameter model we predict analytically and confirm\nexperimentally that the additional subharmonic driving results in controlled\nmotion of the interfaces.",
        "positive": "Freezing and melting line invariants of the Lennard-Jones system: The invariance of several structural and dynamical properties of the\nLennard-Jones (LJ) system along the freezing and melting lines is interpreted\nin terms of the isomorph theory. First the freezing/melting lines for LJ system\nare shown to be approximated by isomorphs. Then we show that the invariants\nobserved along the freezing and melting isomorphs are also observed on other\nisomorphs in the liquid and crystalline phase. Structure is probed by the\nradial distribution function and the structure factor and dynamics is probed by\nthe mean-square displacement, the intermediate scattering function, and the\nshear viscosity. Studying these properties by reference to the isomorph theory\nexplains why known single-phase melting criteria holds, e.g., the Hansen-Verlet\nand the Lindemann criterion, and why the Andrade equation for the viscosity at\nfreezing applies, e.g., for most liquid metals. Our conclusion is that these\nempirical rules and invariants can all be understood from the isomorph theory\nand that the invariants are not peculiar to the freezing and melting lines, but\nhold along all isomorphs."
    },
    {
        "anchor": "Segment Distribution around the Center of Gravity of Branched Polymers: Mathematical expressions for mass distributions around the center of gravity\nare derived for branched polymers with the help of the Isihara formula. We\nintroduce the Gaussian approximation for the end-to-end vector,\n$\\vec{r}_{G\\nu_{i}}$, from the center of gravity to the $i$th mass point on the\n$\\nu$th arm. Then, for star polymers, the result is \\begin{equation}\n\\varphi_{star}(s)=\\frac{1}{N}\\sum_{\\nu=1}^{f}\\sum_{i=1}^{N_{\\nu}}\\left(\\frac{d}{2\\pi\\left\\langle\nr_{G\\nu_{i}}^{2}\\right\\rangle}\\right)^{d/2}\\exp\\left(-\\frac{d}{2\\left\\langle\nr_{G\\nu_{i}}^{2}\\right\\rangle}s^{2}\\right)\\notag \\end{equation} for a\nsufficiently large $N$, where $f$ denotes the number of arms. It is found that\nthe resultant $\\varphi_{star}(s)$ is, unfortunately, not Gaussian. For\ndendrimers \\begin{equation}\n\\varphi_{dend}(s)=\\sum_{h=1}^{g}\\omega_{h}\\left(\\frac{d}{2pi\\left\\langle\nr_{G_{h}}^{2}\\right\\rangle}\\right)^{d/2}\\exp\\left(-\\frac{d}{2\\left\\langle\nr_{G_{h}}^{2}\\right\\rangle}s^{2}\\right)\\notag \\end{equation} where $\\omega_{h}$\ndenotes the weight fraction of masses in the $h$th generation on a dendrimer\nconstructed from $g$ generations, so that $\\sum_{h=1}^{g}\\omega_{h}=1$. To be\nspecific, $\\omega_{1}=1/N$ and $\\omega_{h}=(f-1)^{h-2}/N$ for $h\\ge 2$. These\ndistributions can be described by the same grand sum of each Gaussian function\nfor the end-to-end distance from the center of gravity to each mass point. Note\nthat for a large $f$ and $g$, the statistical weight of younger generations\nbecomes dominant. As a consequence, the mass distribution of unperturbed\ndendrimers approaches the Gaussian form in the limit of a large $f$ and $g$. It\nis shown that the radii of gyration of dendrimers increase logarithmically with\n$N$, which leading to the exponent, $\\nu_{0}=0$. An example of randomly\nbranched polymers is also discussed.",
        "positive": "Interaction of the Torque-Induced Elastic Charge and Elastic Dipole with\n  a Wall in a Nematic Liquid Crystal: We show that the elastic charge of colloids in a nematic liquid crystal can\nbe generated by the vector of external torque. The torque components play the\nrole of two component charge (dyad) and give rise to the Coulomb-like\npotential, while their conservation law plays the role similar to that of\nGauss' theorem in the electrostatics. The theory is applied to the\ncolloid-surface interaction. A wall with homeotropic or planar director is\nshown to induce a repulsive 1/r^4 force on the elastic dipole. The external\ntorque, however, induces the elastic charge in this colloid and triggers\nswitching to the 1/r^2 repulsion."
    },
    {
        "anchor": "Size effects in nonlinear periodic materials exhibiting reversible\n  pattern transformations: This paper focuses on size effects in periodic mechanical metamaterials\ndriven by reversible pattern transformations due to local elastic buckling\ninstabilities in their microstructure. Two distinct loading cases are studied:\ncompression and bending, in which the material exhibits pattern transformation\nin the whole structure or only partially. The ratio between the height of the\nspecimen and the size of a unit cell is defined as the scale ratio. A family of\nshifted microstructures, corresponding to all possible arrangements of the\nmicrostructure relative to the external boundary, is considered in order to\ndetermine the ensemble averaged solution computed for each scale ratio. In the\ncompression case, the top and the bottom edges of the specimens are fully\nconstrained, which introduces boundary layers with restricted pattern\ntransformation. In the bending case, the top and bottom edges are free\nboundaries resulting in compliant boundary layers, whereas additional size\neffects emerge from imposed strain gradient. For comparison, the classical\nhomogenization solution is computed and shown to match well with the ensemble\naveraged numerical solution only for very large scale ratios. For smaller scale\nratios, where a size effect dominates, the classical homogenization no longer\napplies.",
        "positive": "Curvature Distribution of Worm-like Chains in Two and Three Dimensions: Bending of worm-like polymers carries an energy penalty which results in the\nappearance of a persistence length l such that the polymer is straight on\nlength scales smaller than l and bends only on length scales larger than this\nlength. Intuitively, this leads us to expect that the most probable value of\nthe local curvature of a worm-like polymer undergoing thermal fluctuations in a\nsolvent, is zero. We use simple geometric arguments and Monte Carlo simulations\nto show that while this expectation is indeed true for polymers on surfaces (in\ntwo dimensions), in three dimensions the probability of observing zero\ncurvature anywhere along the worm-like chain, vanishes."
    },
    {
        "anchor": "Universal Unfolding of Pitchfork Bifurcations and Shear-Band Formation\n  in Rapid Granular Couette Flow: A numerical bifurcation analysis is carried out to understand the role of\ngravity on the shear-band formation in rapid granular Couette flow. At {\\it\nlow} shear rates, there is a unique solution with a {\\it plug} near the bottom\nwall and a {\\it shear-layer} near the top-wall; this solution mirrors typical\nshearbanding-type profiles in earth-bound shear-cell experiments.\nInterestingly, a {\\it stable} plug near the top-wall is also a solution of\nthese equations at {\\it high} shear rates; there is a multitude of other\nplugged states, with the plugs being located in an ordered fashion within the\nCouette gap. The origin of such shearbanding solutions is tied to the\nspontaneous symmetry-breaking {\\it shearbanding} instabilities of the\ngravity-free uniform shear flow, leading to both subcritical and supercritical\npitchfork bifurcations. In the language of singularity theory, we have\nestablished that this bifurcation problem admits {\\it universal unfolding} of\npitchfork bifurcations.",
        "positive": "Tuning the distance to the equipartition by controlling the collision\n  rate in a driven granular gas experiment: In a granular gas experiment of magnetized particles confined in a thin\nlayer, the rate of dissipative collisions is tuned by adjusting the amplitude\nof an external magnetic field. The velocity statistics are analyzed using the\ndynamic and static structure factors of transverse velocity modes. Using the\nfluctuating hydrodynamics theory we measure the deviation from kinetic energy\nequipartition in this out-of-equilibrium system as a function of the\ndissipative collision rate. When the collision rate is decreased, the distance\nto equipartition becomes smaller meaning that the dynamical properties of this\ngranular gas approach by analogy those of a molecular gas in thermal\nequilibrium."
    },
    {
        "anchor": "Generalization of nonlinear Murnaghan elastic model for viscoelastic\n  materials: This paper presents a generalization of Murnaghan elastic material to\nviscoelastic behavior using the Green-Rivlin multiple-integral approach. In the\nlinear limit, the model coincides with the generalized Maxwell model. To create\na nonlinear generalization, all possible second-order corrections were included\nin the constitutive equations written in the internal strains representation.\nUsing this approach, we obtained expressions for the time- and\nfrequency-dependent nonlinear dynamic moduli. We applied the developed\nnonlinear viscoelastic model to the description of infinitesimal strain waves\nsuperposed on finite prestrain. Furthermore, we considered the generation of\nhigher harmonic by the nonlinear interaction of two strain waves, which we\nshowed can provide a method to measure all viscoelastic constants of the\ndeveloped model.",
        "positive": "Disjoining pressure oscillations causing height discretization in\n  graphene nanobubbles: Recent experiments and computer simulations observe various geometrical\nformations of nanobubbles in van der Waals heterostructures. Among the well\nstudied dome and tent geometries, there is yet least understood pancake\ngraphene nanobubbles (GNB). This more exotic form exhibits discrete values of\nvertical sizes around just a few diameters of the molecules trapped inside the\nGNBs. We develop a model based on the membrane theory and confined fluids\nthermodynamics. Our approach describes the equilibrium properties of such flat\nGNBs. We show that discrete pancake geometry is the result of disjoining\npressure induced by the trapped fluid inside GNB. The calculated total energy\ndefines a discrete series of the metastable states with the pancake heights,\nwhich are multiple to molecular diameter. We observe that the value and the\ndistribution of the total energy minima crucially depend on the temperature.\nThe energy barriers between metastable states decrease as the temperature\nbecomes larger. Also, we demonstrate that the pancake forms are favorable in\nthe cases of sufficiently low membrane-substrate adhesion energy and the small\nnumber of trapped molecules. These properties are in agreement with the\npublished simulations and experiments. The numerical comparison of our result\nwith molecular dynamics results additionally shows the adequacy of the proposed\nmodel."
    },
    {
        "anchor": "The mechanical response of semiflexible networks to localized\n  perturbations: Previous research on semiflexible polymers including cytoskeletal networks in\ncells has suggested the existence of distinct regimes of elastic response, in\nwhich the strain field is either uniform (affine) or non-uniform (non-affine)\nunder external stress. Associated with these regimes, it has been further\nsuggested that a new fundamental length scale emerges, which characterizes the\nscale for the crossover from non-affine to affine deformations. Here, we extend\nthese studies by probing the response to localized forces and force dipoles. We\nshow that the previously identified nonaffinity length [D.A. Head et al. PRE\n68, 061907 (2003).] controls the mesoscopic response to point forces and the\ncrossover to continuum elastic behavior at large distances.",
        "positive": "Entropy, diffusivity and the energy landscape of a water-like fluid: Molecular dynamics simulations and instantaneous normal mode (INM) analysis\nof a fluid with core-softened pair interactions and water-like liquid-state\nanomalies are performed to obtain an understanding of the relationship between\nthermodynamics, transport properties and the poten- tial energy landscape.\nRosenfeld-scaling of diffusivities with the thermodynamic excess and pair\ncorrelation entropy is demonstrated for this model. The INM spectra are shown\nto carry infor- mation about the dynamical consequences of the interplay\nbetween length scales characteristic of anomalous fluids, such as bimodality of\nthe real and imaginary branches of the frequency distribu- tion. The INM\nspectral information is used to partition the liquid entropy into two\ncontributions associated with the real and imaginary frequency modes; only the\nentropy contribution from the imaginary branch captures the non-monotonic\nbehaviour of the excess entropy and diffusivity in the anomalous regime of the\nfluid."
    },
    {
        "anchor": "Cooperativity and Frustration in Protein-Mediated Parallel Actin Bundles: We examine the mechanism of bundling of cytoskeletal actin filaments by two\nrepresentative bundling proteins, fascin and espin. Small-angle X-ray studies\nshow that increased binding from linkers drives a systematic \\textit{overtwist}\nof actin filaments from their native state, which occurs in a linker-dependent\nfashion. Fascin bundles actin into a continuous spectrum of intermediate twist\nstates, while espin only allows for untwisted actin filaments and\nfully-overtwisted bundles. Based on a coarse-grained, statistical model of\nprotein binding, we show that the interplay between binding geometry and the\nintrinsic \\textit{flexibility} of linkers mediates cooperative binding in the\nbundle. We attribute the respective continuous/discontinous bundling mechanisms\nof fascin/espin to differences in the stiffness of linker bonds themselves.",
        "positive": "Averaging rheological quantities in descriptions of soft glassy\n  materials: Many mean-field models have been introduced to describe the mechanical\nbehavior of glassy materials. They often rely on averages performed over\ndistributions of elements or states. We here underline that averaging is a more\nintricate procedure in mechanics than in more classical situations such as\nphase transitions in magnetic systems. This leads us to modify the predictions\nof the recently proposed SGR model for soft glassy materials, for which we\nsuggest that the viscosity should diverge at the glass transition temperature\n$T_g$ with an exponential form $\\eta \\sim \\exp(\\frac{A}{T-T_g})$."
    },
    {
        "anchor": "Stretching dynamics of semiflexible polymers: We analyze the nonequilibrium dynamics of single inextensible semiflexible\nbiopolymers as stretching forces are applied at the ends. Based on different\n(contradicting) heuristic arguments, various scaling laws have been proposed\nfor the propagation speed of the backbone tension which is induced in response\nto stretching. Here, we employ a newly developed unified theory to\nsystematically substantiate, restrict, and extend these approaches. Introducing\nthe practically relevant scenario of a chain equilibrated under some\nprestretching force $f_\\text{pre}$ that is suddenly exposed to a different\nexternal force $f_\\text{ext}$ at the ends, we give a concise physical\nexplanation of the underlying relaxation processes by means of an intuitive\nblob picture. We discuss the corresponding intermediate asymptotics, derive\nresults for experimentally relevant observables, and support our conclusions by\nnumerical solutions of the coarse-grained equations of motion for the tension.",
        "positive": "Mechanics of two filaments in tight contact: The orthogonal clasp: Networks of flexible filaments often involve regions of tight contact.\nPredictively understanding the equilibrium configurations of these systems is\nchallenging due to intricate couplings between topology, geometry, large\nnonlinear deformations, and friction. Here, we perform an in-depth study of a\nsimple yet canonical problem that captures the essence of contact between\nfilaments. In the orthogonal clasp, two filaments are brought into contact,\nwith each centerline lying in one of a pair of orthogonal planes. Our data from\nX-ray tomography (micro-CT) and mechanical testing experiments are in excellent\nagreement with the finite element method (FEM) simulations. Despite the\napparent simplicity of the physical system, the data exhibits strikingly\nunintuitive behavior, even when the contact is frictionless. Specifically, we\nobserve a curvilinear diamond-shaped ridge in the contact pressure field\nbetween the two filaments, sometimes with an inner gap. When a relative\ndisplacement is imposed between the filaments, friction is activated, and a\nhighly asymmetric pressure field develops. These findings contrast to the\nclassic capstan analysis of a single filament wrapped around a rigid body. Both\nthe micro-CT and the FEM data indicate that the cross-sections of the filaments\ncan deform significantly. Nonetheless, an idealized geometrical theory assuming\nundeformable tube cross-sections and neglecting elasticity rationalizes our\nobservations qualitatively and highlights the central role of the small but\nfinite tube radius of the filaments. We believe that our orthogonal clasp\nanalysis provides a building block for future modeling efforts in frictional\ncontact mechanics of more complex filamentary structures."
    },
    {
        "anchor": "Micromechanical theory of strain-stiffening of biopolymer networks: Filamentous bio-materials such as fibrin or collagen networks exhibit an\nenormous stiffening of their elastic moduli upon large deformations. This\npronounced nonlinear behavior stems from a significant separation between the\nstiffnesses scales associated with bending vs. stretching the material's\nconstituent elements. Here we study a simple model of such materials - floppy\nnetworks of hinged rigid bars embedded in an elastic matrix - in which the\neffective ratio of bending to stretching stiffnesses vanishes identically. We\nintroduce a theoretical framework and build upon it to construct a numerical\nmethod with which the model's micro- and macro-mechanics can be carefully\nstudied. Our model, numerical method and theoretical framework allow us to\nrobustly observe and fully understand the critical properties of the athermal\nstrain-stiffening transition that underlies the nonlinear mechanical response\nof a broad class of biomaterials.",
        "positive": "Multi-Particle Collision Dynamics Algorithm for Nematic Fluids: Research on transport, self-assembly and defect dynamics within confined,\nflowing liquid crystals requires versatile and computationally efficient\nmesoscopic algorithms to account for fluctuating nematohydrodynamic\ninteractions. We present a multi-particle collision dynamics (MPCD) based\nalgorithm to simulate liquid-crystal hydrodynamic and director fields in two\nand three dimensions. The nematic-MPCD method is shown to successfully\nreproduce the features of a nematic liquid crystal, including a\nnematic-isotropic phase transition with hysteresis in 3D, defect dynamics,\nisotropic Frank elastic coefficients, tumbling and shear alignment regimes and\nboundary condition dependent order parameter fields."
    },
    {
        "anchor": "Continuous Paranematic-to-Nematic Ordering Transitions of Liquid\n  Crystals in Tubular Silica Nanochannels: The optical birefringence of rod-like nematogens (7CB, 8CB), imbibed in\nparallel silica channels with 10 nm diameter and 300 micrometer length, is\nmeasured and compared to the thermotropic bulk behavior. The orientational\norder of the confined liquid crystals, quantified by the uniaxial nematic\nordering parameter, evolves continuously between paranematic and nematic\nstates, in contrast to the discontinuous isotropic-to-nematic bulk phase\ntransitions. A Landau-de Gennes model reveals that the strength of the\norientational ordering fields, imposed by the silica walls, is beyond a\ncritical threshold, that separates discontinuous from continuous\nparanematic-to-nematic behavior. Quenched disorder effects, attributable to\nwall irregularities, leave the transition temperatures affected only\nmarginally, despite the strong ordering fields in the channels.",
        "positive": "Coulomb-blockade transport in quasi-one dimensional polymer nanofibers: We report the low temperature current-voltage (I-V) characteristics studies\nin quasi-one dimensional conducting polymer nanofibers. We find a threshold\nvoltage Vt below which little current flows at temperatures below 30-40 K. For\nV > Vt current scales as (V/Vt - 1)^zeta, where zeta ~ 1.8-2.1 at high biases.\nDifferential conductance oscillations are found whose magnitude increases as\ntemperature decreases below 10 K. We attribute the observed low temperature I-V\nbehavior to Coulomb blockade effects with a crossover to Luttinger liquid-like\nbehavior at high temperature. We demonstrate that at low temperatures such a\ndoped conjugated polymer fiber can be considered as an array of small\nconducting regions separated by nanoscale barriers, where the Coulomb blockade\ntunneling is the dominant transport mechanism."
    },
    {
        "anchor": "Folding of Pig Gastric Mucin Non-glycosylated Domains: A Discrete\n  Molecular Dynamics Study: Mucin glycoprotein consist of tandem repeating glycosylated regions flanked\nby non-repetitive protein domains with little glycosylation. These\nnon-repetitive domains are involved in the pH dependent gelation of gastric\nmucin, which is essential to protecting the stomach from autodigestion. We have\nexamined the folding of the non-repetitive sequence of von Willebrand factor\nvWF-C1 domain (67 amino acids) and PGM 2X (242 amino acids) at neutral and low\npH using Discrete Molecular Dynamics. A four-bead protein model with hydrogen\nbonding and amino acid-specific hydrophobic/hydrophilic and electrostatic\ninteractions of side chains) was used. The simulations reveal that the distant\nN- and C-terminal regions form salt-bridges at neutral pH giving a relatively\ncompact folded structure. At low pH, the salt bridges break giving a more open\nand extended structure. The calculated average value of the beta-strand\nincreases from 0.23 at neutral pH to 0.36 at low pH in very good agreement with\nCD data. Simulations of vWF C1 show 4-6 beta strands separated by turns/loops\nand we found that pH did not affect significantly the folded structure. The\naverage beta-strand structure of 0.32 was again in very good agreement with the\nCD results.",
        "positive": "Nanoalignment by Critical Casimir Torques: The manipulation of microscopic objects requires precise and controllable\nforces and torques. Recent advances have led to the use of critical Casimir\nforces as a powerful tool, which can be finely tuned through the temperature of\nthe environment and the chemical properties of the involved objects. For\nexample, these forces have been used to self-organize ensembles of particles\nand to counteract stiction caused by Casimir-Liftshitz forces. However, until\nnow, the potential of critical Casimir torques has been largely unexplored.\nHere, we demonstrate that critical Casimir torques can efficiently control the\nalignment of microscopic objects on nanopatterned substrates. We show\nexperimentally and corroborate with theoretical calculations and Monte Carlo\nsimulations that circular patterns on a substrate can stabilize the position\nand orientation of microscopic disks. By making the patterns elliptical, such\nmicrodisks can be subject to a torque which flips them upright while\nsimultaneously allowing for more accurate control of the microdisk position.\nMore complex patterns can selectively trap 2D-chiral particles and generate\nparticle motion similar to non-equilibrium Brownian ratchets. These findings\nprovide new opportunities for nanotechnological applications requiring precise\npositioning and orientation of microscopic objects."
    },
    {
        "anchor": "Analysis of electro-osmotic flow in a microchannel with undulated\n  surfaces: The electro-osmotic flow through a channel between two undulated surfaces\ninduced by an external electric field is investigated. The gap of the channel\nis very small and comparable to the thickness of the electrical double layers.\nA lattice Boltzmann simulation is carried out on the model consisting of the\nPoisson equation for electrical potential, the Nernst--Planck equation for ion\nconcentration, and the Navier--Stokes {\\color{black}equations} for flows of the\nelectrolyte solution. An analytical model that predicts the flow rate is also\nderived under the assumption that the channel width is very small compared with\nthe characteristic length of the variation along the channel. The analytical\nresults are compared with the numerical results obtained by using the lattice\nBoltzmann method. In the case of a constant surface charge density along the\nchannel, the variation of the channel width reduces the electro-osmotic flow,\nand the flow rate is smaller than that of a straight channel. In the case of a\nsurface charge density distributed in homogeneously, one-way flow occurs even\nunder the restriction of a zero net surface charge along the channel.",
        "positive": "Solvent contribution to the stability of a physical gel characterized by\n  quasi-elastic neutron scattering: The dynamics of a physical gel, namely the Low Molecular Mass Organic Gelator\n{\\textit Methyl-4,6-O-benzylidene-$\\alpha$ -D-mannopyranoside ($\\alpha$-manno)}\nin water and toluene are probed by neutron scattering. Using high gelator\nconcentrations, we were able to determine, on a timescale from a few ps to 1\nns, the number of solvent molecules that are immobilised by the rigid network\nformed by the gelators. We found that only few toluene molecules per gelator\nparticipate to the network which is formed by hydrogen bonding between the\ngelators' sugar moieties. In water, however, the interactions leading to the\ngel formations are weaker, involving dipolar, hydrophobic or $\\pi-\\pi$\ninteractions and hydrogen bonds are formed between the gelators and the\nsurrounding water. Therefore, around 10 to 14 water molecules per gelator are\nimmobilised by the presence of the network. This study shows that neutron\nscattering can give valuable information about the behaviour of solvent\nconfined in a molecular gel."
    },
    {
        "anchor": "Training precise stress patterns: We introduce a training rule that enables a network composed of springs and\ndashpots to learn precise stress patterns. Our goal is to control the tensions\non a fraction of \"target\" bonds, which are chosen randomly. The system is\ntrained by applying stresses to the target bonds, causing the remaining bonds,\nwhich act as the learning degrees of freedom, to evolve. Different criteria for\nselecting the target bonds affects whether frustration is present. When there\nis at most a single target bond per node the error converges to computer\nprecision. Additional targets on a single node may lead to slow convergence and\nfailure. Nonetheless, training is successful even when approaching the limit\npredicted by the Maxwell Calladine theorem. We demonstrate the generality of\nthese ideas by considering dashpots with yield stresses. We show that training\nconverges, albeit with a slower, power-law decay of the error. Furthermore,\ndashpots with yielding stresses prevent the system from relaxing after\ntraining, enabling to encode permanent memories.",
        "positive": "Transient shear banding in the nematic dumbbell model of liquid\n  crystalline polymers: In the shear flow of liquid crystalline polymers (LCPs) the nematic director\norientation can align with the flow direction for some materials, but\ncontinuously tumble in others. The nematic dumbbell (ND) model was originally\ndeveloped to describe the rheology of flow-aligning semi-flexible LCPs, and\nflow-aligning LCPs are the focus in this paper. In the shear flow of monodomain\nLCPs it is usually assumed that the spatial distribution of the velocity is\nuniform. This is in contrast to polymer solutions, where highly non-uniform\nspatial velocity profiles have been observed in experiments. We analyse the ND\nmodel, with an additional gradient term in the constitutive model, using a\nlinear stability analysis. We investigate the separate cases of constant\napplied shear stress, and constant applied shear rate. We find that the ND\nmodel has a transient flow instability to the formation of a spatially\ninhomogeneous flow velocity for certain starting orientations of the director.\nWe calculate the spatially resolved flow profile in both constant applied\nstress and constant applied shear rate in start up from rest, using a model\nwith one spatial dimension to illustrate the flow behaviour of the fluid. For\nlow shear rates flow reversal can be seen as the director realigns with the\nflow direction, whereas for high shear rates the director reorientation occurs\nsimultaneously across the gap. Experimentally, this inhomogeneous flow is\npredicted to be observed in flow reversal experiments in LCPs."
    },
    {
        "anchor": "Hydrodynamics of Random-Organizing Hyperuniform Fluids: Disordered hyperuniform structures are locally random while uniform like\ncrystals at large length scales. Recently, an exotic hyperuniform fluid state\nwas found in several non-equilibrium systems, while the underlying physics\nremains unknown. In this work, we propose a non-equilibrium\n(driven-dissipative) hard-sphere model and formulate a hydrodynamic theory\nbased on Navier-Stokes equations to uncover the general mechanism of the\nfluidic hyperuniformity (HU). At a fixed density, this model system undergoes a\nsmooth transition from an absorbing state to an active hyperuniform fluid, then\nto the equilibrium fluid by changing the dissipation strength. We study the\ncriticality of the absorbing phase transition. We find that the origin of\nfluidic HU can be understood as the damping of a stochastic harmonic oscillator\nin $q$ space, which indicates that the suppressed long-wavelength density\nfluctuation in the hyperuniform fluid can exhibit as either acoustic\n(resonance) mode or diffusive (overdamped) mode. Importantly, our theory\nreveals that the damping dissipation and active reciprocal interaction\n(driving) are two ingredients for fluidic HU. Based on this principle, we\nfurther demonstrate how to realize the fluidic HU in an experimentally\naccessible active spinner system and discuss the possible realization in other\nsystems.",
        "positive": "Attractive instability of oppositely charged membranes induced by charge\n  density fluctuations: We predict the conditions under which two oppositely charged membranes show a\ndynamic, attractive instability. Two layers with unequal charges of opposite\nsign can repel or be stable when in close proximity. However, dynamic charge\ndensity fluctuations can induce an attractive instability and thus facilitate\nfusion. We predict the dominant instability modes and timescales and show how\nthese are controlled by the relative charge and membrane viscosities. These\ndynamic instabilities may be the precursors of membrane fusion in systems where\nartificial vesicles are engulfed by biological cells of opposite charge."
    },
    {
        "anchor": "Understanding the Nonlinear Dynamics of Driven Particles in Supercooled\n  Liquids in Terms of an Effective Temperature: In active microrheology the mechanical properties of a material are tested by\nadding probe particles which are pulled by an external force. In case of\nsupercooled liquids, strong forcing leads to a thinning of the host material\nwhich becomes more pronounced as the system approaches the glass transition. In\nthis work we provide a quantitative theoretical description of this thinning\nbehavior based on the properties of the Potential Energy Landscape (PEL) of a\nmodel glass-former. A key role plays the trap-like nature of the PEL. We find\nthat the mechanical properties in the strongly driven system behave the same as\nin a quiescent system at an enhanced temperature, giving rise to a\nwell-characterized effective temperature. Furthermore, this effective\ntemperature turns out to be independent of the chosen observable and\nindividually shows up in the thermodynamic and dynamic properties of the\nsystem. Based on this underlying theoretical understanding, we can estimate its\ndependence on temperature and force by the PEL-properties of the quiescent\nsystem. We furthermore critically discuss the relevance of effective\ntemperatures obtained by scaling relations for the description of\nout-of-equilibrium situations.",
        "positive": "A New Model For Incorporating the Variations of the Dielectric\n  Permittivity of the Medium: Part (1)Potential Distribution of an Electrical\n  Double Layer in Rectangular Nano channel by Applying Finite Element Method\n  Technique: The effect of the dielectric permittivity of the electrolytic medium in the\nElectrical Double Layer (EDL) in Nanochannel is an important factor that\nrequires a correction, before the application of the model in various chemical\nand biomedical examinations. However very few efforts are put forth to\naccommodate this into the mathematics of the EDL Models developed hitherto,\neven though it was realized by a host of authors for the past half a century or\neven more. Most of the Nanoc hannel made lab-on-chips in a rectangular cross\nsection require suitable impregnation of this. The effect of the EDL in a\nnanochannel isimportant in various chemical and biomedical examinations. Most\nof the nanochannelmadelab on chips in a rectangular cross section. The EDL\ninsuch a nanochannel is governed by two dimensional Gouy Chapman (GC)equation."
    },
    {
        "anchor": "Cooperativity in Protein Folding: From Lattice Models with Side Chains\n  to Real Proteins: We consider equilibrium folding transitions in lattice protein models with\nand without side chains. A dimensionless measure, $Omega_{c}$, is introduced to\nquantitatively assess the degree of cooperativity in lattice models and in real\nproteins. We show that larger values of $\\Omega_{c}$ resembling those seen in\nproteins are obtained in lattice models with side chains (LMSC). The enhanced\ncooperativity in LMSC is due to the possibility of denser packing of side\nchains in the interior of the model protein. We also establish that\n$\\Omega_{c}$ correlates extremely well with (\\sigma = (T_{\\theta} -T_{f}\n)/T_{\\theta}), where (T_{\\theta}) and (T_{f}) are collapse and folding\ntransition temperatures, respectively. These theoretical ideas are used to\nanalyze folding transitions in various real proteins. The values of $\\Omega\n_{c}$ extracted from experiments show a correlation with $\\sigma $. We conclude\nthat the degree of cooperativity can be expressed in terms of the single\nparameter $\\sigma $, which can be estimated from experimental data.",
        "positive": "Evolution of dynamical facilitation approaching the granular glass\n  transition: We investigate the relaxation dynamics of a dense monolayer of bidisperse\nbeads by analyzing the experimental data previously obtained in a fluidized\nbed. We show that the dynamics is formed by elementary relaxation events called\ncage jumps. These aggregate on a very short time into clusters. Increasing the\npacking fraction makes the spatio-temporal organization of the clusters evolve\nfrom a rather scattered and random distribution towards a collection of sparse\nand large events, called avalanches. The avalanche process is a manifestation\nof dynamical facilitation. The study of its evolution with density reveals that\ndynamical facilitation becomes less conserved and play a lesser role for the\nstructural relaxation approaching the granular glass transition."
    },
    {
        "anchor": "Hydrodynamic simulations of self-phoretic microswimmers: A mesoscopic hydrodynamic model to simulate synthetic self-propelled Janus\nparticles which is thermophoretically or diffusiophoretically driven is here\ndeveloped. We first propose a model for a passive colloidal sphere which\nreproduces the correct rotational dynamics together with strong phoretic\neffect. This colloid solution model employs a multiparticle collision dynamics\ndescription of the solvent, and combines potential interactions with the\nsolvent, with stick boundary conditions. Asymmetric and specific colloidal\nsurface is introduced to produce the properties of self-phoretic Janus\nparticles. A comparative study of Janus and microdimer phoretic swimmers is\nperformed in terms of their swimming velocities and induced flow behavior.\nSelf-phoretic microdimers display long range hydrodynamic interactions and can\nbe characterized as pullers or pushers. In contrast, Janus particles are\ncharacterized by short range hydrodynamic interactions and behave as neutral\nswimmers. Our model nicely mimics those recent experimental realization of the\nself-phoretic Janus particles.",
        "positive": "Volume analysis of supercooled water under high pressure: Motivated by an experimental finding on the density of supercooled water at\nhigh pressure [O. Mishima, J. Chem. Phys. 133, 144503 (2010)] we performed\natomistic molecular dynamics simulations study of bulk water in the\nisothermal-isobaric ensemble. Cooling and heating cycles at different isobars\nand isothermal compression at different temperatures are performed on the water\nsample with pressures that range from 0 to 1.0 GPa. The cooling simulations are\ndone at temperatures that range from 40 K to 380 K using two different cooling\nrates, 10 K/ns and 10 K/5 ns. For the heating simulations we used the slowest\nheating rate (10 K/5 ns) by applying the same range of isobars. Our analysis of\nthe variation of the volume of the bulk water sample with temperature at\ndifferent pressures from both isobaric cooling/heating and isothermal\ncompression cycles indicates a concave-downward curvature at high pressures\nthat is consistent with the experiment for emulsified water. In particular, a\nstrong concave down curvature is observed between the temperatures 180 K and\n220 K. Below the glass transition temperature, which is around 180 K at 1GPa,\nthe volume turns to concave upward curvature. No crystallization of the\nsupercooled liquid state was observed below 180 K even after running the system\nfor an additional microsecond."
    },
    {
        "anchor": "Dynamic arrest of colloids in porous environments: disentangling\n  crowding and confinement: Using numerical simulations we study the slow dynamics of a colloidal\nhard-sphere fluid adsorbed in a matrix of disordered hard-sphere obstacles. We\ncalculate separately the contributions to the single-particle dynamic\ncorrelation functions due to free and trapped particles. The separation is\nbased on a Delaunay tessellation to partition the space accessible to the\ncentres of fluid particles into percolating and disconnected voids. We find\nthat the trapping of particles into disconnected voids of the matrix is\nresponsible for the appearance of a nonzero long-time plateau in the\nsingle-particle intermediate scattering functions of the full fluid. The\nsubdiffusive exponent $z$, obtained from the logarithmic derivative of the\nmean-squared displacement, is observed to be essentially unaffected by the\nmotion of trapped particles: close to the percolation transition, we determined\n$z \\simeq 0.5$ for both the full fluid and the particles moving in the\npercolating void. Notably, the same value of $z$ is found in single-file\ndiffusion and is also predicted by mode-coupling theory along the\ndiffusion-localisation line. We also reveal subtle effects of dynamic\nheterogeneity in both the free and the trapped component of the fluid\nparticles, and discuss microscopic mechanisms that contribute to this\nphenomenon.",
        "positive": "Electron bubbles in liquid helium: infrared-absorption spectrum: Within Density Functional Theory, we have calculated the energy of the\ntransitions from the ground state to the first two excited states in the\nelectron bubbles in liquid helium at pressures from zero to about the\nsolidification pressure.\n  For $^4$He at low temperatures, our results are in very good agreement with\ninfrared absorption experiments. Above a temperature of $\\sim 2$ K, we\noverestimate the energy of the $1s-1p$ transition. We attribute this to the\nbreak down of the Franck-Condon principle due to the presence of helium vapor\ninside the bubble. Our results indicate that the $1s-2p$ transition energies\nare sensitive not only to the size of the electron bubble, but also to its\nsurface thickness. We also present results for the infrared transitions in the\ncase of liquid $^3$He, for which we lack of experimental data."
    },
    {
        "anchor": "Scaling of Entropic Shear Rigidity: The scaling of the shear modulus near the gelation/vulcanization transition\nis explored heuristically and analytically. It is found that in a dense melt\nthe effective chains of the infinite cluster have sizes that scale sub-linearly\nwith their contour length. Consequently, each contributes k_B T to the\nrigidity, which leads to a shear modulus exponent d\\nu. In contrast, in phantom\nelastic networks the scaling is linear in the contour length, yielding an\nexponent identical to that of the random resistor network conductivity, as\npredicted by de Gennes'. For non-dense systems, the exponent should cross over\nto d\\nu when the percolation length becomes much larger than the\ndensity-fluctuation length.",
        "positive": "The thermodynamical liquid-glass transition in a Lennard-Jones binary\n  mixture: We use the results derived in the framework of the replica approach to study\nthe liquid-glass thermodynamic transition. The main results are rederived\nwithout using replicas and applied to the study of the Lennard-Jones binary\nmixture introduced by Kob and Andersen. We find that there is a phase\ntransition due to the entropy crisis. We compute both analytically and\nnumerically the value of the phase transition point $T_{K}$ and the specific\nheat in the low temperature phase."
    },
    {
        "anchor": "Theory of random packings: We review a recently proposed theory of random packings. We describe the\nvolume fluctuations in jammed matter through a volume function, amenable to\nanalytical and numerical calculations. We combine an extended statistical\nmechanics approach 'a la Edwards' (where the role traditionally played by the\nenergy and temperature in thermal systems is substituted by the volume and\ncompactivity) with a constraint on mechanical stability imposed by the\nisostatic condition. We show how such approaches can bring results that can be\ncompared to experiments and allow for an exploitation of the statistical\nmechanics framework. The key result is the use of a relation between the local\nVoronoi volume of the constituent grains and the number of neighbors in contact\nthat permits a simple combination of the two approaches to develop a theory of\nrandom packings. We predict the density of random loose packing (RLP) and\nrandom close packing (RCP) in close agreement with experiments and develop a\nphase diagram of jammed matter that provides a unifying view of the disordered\nhard sphere packing problem and further shedding light on a diverse spectrum of\ndata, including the RLP state. Theoretical results are well reproduced by\nnumerical simulations that confirm the essential role played by friction in\ndetermining both the RLP and RCP limits. Finally we present an extended\ndiscussion on the existence of geometrical and mechanical coordination numbers\nand how to measure both quantities in experiments and computer simulations.",
        "positive": "Dissipative flows of 2D foams: We analyze the flow of a liquid foam between two plates separated by a gap of\nthe order of the bubble size (2D foam). We concentrate on the salient features\nof the flow that are induced by the presence, in an otherwise monodisperse\nfoam, of a single large bubble whose size is one order of magnitude larger than\nthe average size. We describe a model suited for numerical simulations of flows\nof 2D foams made up of a large number of bubbles. The numerical results are\nsuccessfully compared to analytical predictions based on scaling arguments and\non continuum medium approximations. When the foam is pushed inside the cell at\na controlled rate, two basically different regimes occur: a plug flow is\nobserved at low flux whereas, above a threshold, the large bubble migrates\nfaster than the mean flow. The detailed characterization of the relative\nvelocity of the large bubble is the essential aim of the present paper. The\nrelative velocity values, predicted both from numerical and from analytical\ncalculations that are discussed here in great detail, are found to be in fair\nagreement with experimental results."
    },
    {
        "anchor": "Excluded volume effect in flexible dendrimer systems: A self-consistent\n  field theory: We have studied the conformational and scaling behaviors of a flexible\ndendrimer immersed in athermal or good solvents. A self-consistent field theory\ncombined with a pre-averaged excluded volume potential representing the\ntwo-body short-ranged interaction between the segments, was adopted to\ncalculate the density profile of various generations and branch points\nthoroughly. Our calculation results support the \"dense-core\" model. We find the\nconformation of the dendrimer is strongly stretched in the dense central\nregion, but much weakly stretched in the outer region where the segment density\nprofile is shoulder shaped. Both our self-consistent field theory calculation\nand the Flory mean-field theory calculation give the same scaling law R\nproportional to (GP)^0.2N^0.4, where G is the generation number of the\ndendrimer, P is the spacer segment number, and N is the total segment number.\nIf we fix G, the scaling law is simplified to R proportional to P^0.6 in good\nsolvent.",
        "positive": "Comparing different coarse-grained potentials for star polymers: We compare different coarse-grained models for star polymers. We find that\nphenomenological models inspired by the Daoud-Cotton model reproduce quite\npoorly the thermodynamics of these systems, even if the potential is assumed to\nbe density dependent, as done in the analysis of experimental results. We also\ndetermine the minumum value fc of the functionality of the star polymer for\nwhich a fluid-solid transition occurs. By applying the Hansen-Verlet criterion\nwe find 35 < fc < 40. This result is confirmed by an analysis based on the\nmodified (reference) hypernetted chain method and is qualitatively consistent\nwith previous work."
    },
    {
        "anchor": "Minimal two-sphere model of the generation of fluid flow at low Reynolds\n  numbers: Locomotion and generation of flow at low Reynolds number are subject to\nsevere limitations due to the irrelevance of inertia: the \"scallop theorem\"\nrequires that the system have at least two degrees of freedom, which move in\nnon-reciprocal fashion, i.e. breaking time-reversal symmetry. We show here that\na minimal model consisting of just two spheres driven by harmonic potentials is\ncapable of generating flow. In this pump system the two degrees of freedom are\nthe mean and relative positions of the two spheres. We have performed and\ncompared analytical predictions, numerical simulation and experiments, showing\nthat a time-reversible drive is sufficient to induce flow.",
        "positive": "Dynamics of a driven probe molecule in a liquid monolayer: We study dynamics of a probe molecule, driven by an external constant force\nin a liquid monolayer on top of solid surface. In terms of a microscopic,\nmean-field-type approach, we calculate the terminal velocity of the probe\nmolecule. This allows us to establish the analog of the Stokes formula, in\nwhich the friction coefficient is interpreted in terms of the microscopic\nparameters characterizing the system. We also determine the distribution of the\nmonolayer particles as seen from the stationary moving probe molecule and\nestimate the self-diffusion coefficient for diffusion in a liquid monolayer."
    },
    {
        "anchor": "Phase Separation in Peptide Aggregation Processes - Multicanonical Study\n  of a Mesoscopic Model: We have performed multicanonical computer simulations of a small system of\nshort protein-like heteropolymers and found that their aggregation transition\npossesses similarities to first-order phase separation processes. Not being a\nphase transition in the thermodynamic sense, the observed folding-binding\nbehavior exhibits fascinating features leading to the conclusion that the\ntemperature is no suitable control parameter in the transition region. More\nformally, for such small systems the microcanonical interpretation is more\nfavorable than the typically used canonical picture.",
        "positive": "Hyperuniformity of Maximally Random Jammed Packings of Hyperspheres\n  Across Spatial Dimensions: The maximally random jammed (MRJ) state is the most random configuration of\nstrictly jammed (mechanically rigid) nonoverlapping objects. MRJ packings are\nhyperuniform, meaning their long-wavelength density fluctuations are\nanomalously suppressed compared to typical disordered systems, i.e., their\nstructure factors $S(\\mathbf{k})$ tend to zero as the wavenumber $|\\mathbf{k}|$\ntends to zero. Here, we show that generating high-quality strictly jammed\nstates for space dimensions $d = 3,4,$ and $5$ is of paramount importance in\nensuring hyperuniformity and extracting precise values of the hyperuniformity\nexponent $\\alpha > 0$ for MRJ states, defined by the power-law behavior of\n$S(\\mathbf{k})\\sim|\\mathbf{k}|^{\\alpha}$ in the limit\n$|\\mathbf{k}|\\rightarrow0$. Moreover, we show that for fixed $d$ it is more\ndifficult to ensure jamming as the particle number $N$ increases, which results\nin packings that are nonhyperuniform. Free-volume theory arguments suggest that\nthe ideal MRJ state does not contain rattlers, which act as defects in\nnumerically generated packings. As $d$ increases, we find that the fraction of\nrattlers decreases substantially. Our analysis of the largest truly jammed\npackings suggests that the ideal MRJ packings for all dimensions $d\\geq3$ are\nhyperuniform with $\\alpha = d - 2$, implying the packings become more\nhyperuniform as $d$ increases. The differences in $\\alpha$ between MRJ packings\nand recently proposed Manna-class random close packed (RCP) states, which were\nreported to have $\\alpha = 0.25$ in $d=3$ and be nonhyperuniform ($\\alpha = 0$)\nfor $d = 4$ and $d = 5$, demonstrate the vivid distinctions between the\nlarge-scale structure of RCP and MRJ states in these dimensions. Our work\nclarifies the importance of the link between true jamming and hyperuniformity\nand motivates the development of an algorithm to produce rattler-free\nthree-dimensional MRJ packings."
    },
    {
        "anchor": "Ground state and thermal properties of a lattice gas on a cylindrical\n  surface: Adsorbed gases within, or outside of, carbon nanotubes may be analyzed with\nan approximate model of adsorption on lattice sites situated on a cylindrical\nsurface. Using this model, the ground state energies of alternative lattice\nstructures are calculated, assuming Lennard-Jones pair interactions between the\nparticles. The resulting energy and equilibrium structure are nonanalytic\nfunctions of radius (R) because of commensuration effects associated with the\ncylindrical geometry.\n  Specifically, as R varies, structural transitions occur between\nconfigurations differing in the \"ring number\", defined as the number of atoms\nlocated at a common value of the longitudinal coordinate (z). The thermodynamic\nbehavior of this system is evaluated at finite temperatures, using a\nHamiltonian with nearest-neighbor interactions. The resulting specific heat\nbears a qualitative resemblance to that of the one-dimensional Ising model.",
        "positive": "Phase stacking diagram of colloidal mixtures under gravity: The observation of stacks of distinct layers in a colloidal or liquid mixture\nin sedimentation-diffusion equilibrium is a striking consequence of bulk phase\nseparation. Drawing quantitative conclusions about the phase diagram is,\nhowever, very delicate. Here we introduce the Legendre transform of the\nchemical potential representation of the bulk phase diagram to obtain a unique\nstacking diagram of all possible stacks under gravity. Simple bulk phase\ndiagrams generically lead to complex stacking diagrams. We apply the theory to\na binary hard core platelet mixture with only two-phase bulk coexistence, and\nfind that the stacking diagram contains six types of stacks with up to four\ndistinct layers. These results can be tested experimentally in colloidal\nplatelet mixtures. In general, an extended Gibbs phase rule determines the\nmaximum number of sedimented layers to be $3+2(n_b-1)+n_i$, where $n_b$ is the\nnumber of binodals and $n_i$ is the number of their inflection points."
    },
    {
        "anchor": "Characterizing Different Motility Induced Regimes in Active Matter with\n  Machine Learning and Noise: We examine motility-induced phase separation (MIPS) in two-dimensional run\nand tumble disk systems using both machine learning and noise fluctuation\nanalysis. Our measures suggest that within the MIPS state there are several\ndistinct regimes as a function of density and run time, so that systems with\nMIPS transitions exhibit an active fluid, an active crystal, and a critical\nregime. The different regimes can be detected by combining an order parameter\nextracted from principal component analysis with a cluster stability\nmeasurement. The principal component-derived order parameter is maximized in\nthe critical regime, remains low in the active fluid, and has an intermediate\nvalue in the active crystal regime. We demonstrate that machine learning can\nbetter capture dynamical properties of the MIPS regimes compared to more\nstandard structural measures such as the maximum cluster size. The different\nregimes can also be characterized via changes in the noise power of the\nfluctuations in the average speed. In the critical regime, the noise power\npasses through a maximum and has a broad spectrum with a $1/f^{1.6}$ signature,\nsimilar to the noise observed near depinning transitions or for solids\nundergoing plastic deformation.",
        "positive": "Hierarchical structured surfaces enhance the contact angle of the\n  hydrophobic (meta-stable) state: The relation between wetting properties and geometric parameters of fractal\nsurfaces are widely discussed on the literature and, however, there are still\ndivergences on this topic. Here we propose a simple theoretical model to\ndescribe the wetting properties of a droplet of water placed on a hierarchical\nstructured surface and test the predictions of the model and the dependence of\nthe droplet wetting state on the initial conditions using simulation of the\n3-spin Potts model. We show that increasing the auto-similarity level of the\nhierarchy -- called $n$ -- does not affect considerably the stable wetting\nstate of the droplet but increases its contact angle. Simulations also explicit\nthe existence of metastable states on this type of surfaces and shows that,\nwhen $n$ increases, the metastability becomes more pronounced. Finally we show\nthat the fractal dimension of the surface is not a good predictor of the\ncontact angle of the droplet."
    },
    {
        "anchor": "Enzymatic Logic Gates with Noise-Reducing Sigmoid Response: Biochemical computing is an emerging field of unconventional computing that\nattempts to process information with biomolecules and biological objects using\ndigital logic. In this work we survey filtering in general, in biochemical\ncomputing, and summarize the experimental realization of an AND logic gate with\nsigmoid response in one of the inputs. The logic gate is realized with\nelectrode-immobilized glucose-6-phosphate dehydrogenase enzyme that catalyzes a\nreaction corresponding to the Boolean AND functions. A kinetic model is also\ndeveloped and used to evaluate the extent to which the performance of the\nexperimentally realized logic gate is close to optimal.",
        "positive": "Segment Distribution around the Center of Gravity of Ring Polymers:\n  Extension of the Kramers Method: The segment distribution around the center of gravity is derived for\nunperturbed ring polymers. We show that, although a small difference is\nobserved, the exact distribution can be well approximated by the Gaussian\nprobability distribution function."
    },
    {
        "anchor": "Molecular association at the microscopic level: The Helmholtz free-energy W is calculated as a function of separation\ndistance for two molecules in a fluid, A and B, whose mutual interaction is\ndescribed by a spherically symmetric potential. For the equilibrium A + B = AB\noccurring in a dilute solution or gas, W is used to evaluate the association\nconstant K, which for ionic A and B is identical to the Bjerrum result. The\ncriterion defining the bound species is not arbitrary; i.e., the cutoff\nseparation distance in the configuration integral used to calculate K arises\ndirectly from the definition of W. For a one-component dense fluid, W permits\nthe derivation of the phase-condensation temperature, which for a gas is the\ncritical temperature and for a liquid the freezing temperature. For ionic A and\nB (e.g., Sodium and Chloride ions in molten NaCl), an expression for the\nfreezing temperature is obtained, which is similar to the expression for the\nmelting temperature derived by Kosterlitz and Thouless for two-dimensional\nsystems.",
        "positive": "The ground state and the character of the interaction between a\n  colloidal particles in a liquid crystals: In this article is proposed the general approach to determination the\ncharacter of the interaction between colloidal particles in a different liquid\ncrystals. The main idea of this approach are in the presentation of the\ncolloidal particle as sours of the possible deformation of the ground state of\nthe director field. The ground state of liquid crystal imposes restrictions on\nthe possible deformations and as result determine the character of the\ninteraction between the colloidal particles. Based on this approach the Coulomb\nlike interaction between dipole particles in a cholesteric liquid crystal and\nchanging of the character of the interaction in a smactic liquid crystal has\nbeen predicted."
    },
    {
        "anchor": "A Simulation Study on Multicomponent Lipid Bilayer: Simulation of a multicomponent lipid bilayer having a fixed percentage of\ncholesterol is done to study phase transition leading to domain formation. The\nconcept of random lattice has been used in simulation to account for the\ncoupling between the internal and translational degrees of freedom of lipid\nmolecules. Considering a canonical ensemble, dissimilar lipid molecules are\nallowed to exchange their positions in the lattice subject to standard\nmetropolis algorithm. The steps involved in the process effectively takes into\naccount for the movement of sphingolipids and cholesterol molecules helping\nformation of cholesterol rich domains of saturated lipids as found in natural\nmembranes.",
        "positive": "Viscoelastic properties and flow instabilities of aqueous suspensions of\n  cellulosic fibers: Processing of concentrated lignocellulosic biomass suspensions typically\ninvolves the conversion of the cellulose into sugars and sugars into ethanol.\nBiomass is usually pre-processed (i.e. via comminution, steam explosion, etc.)\nto form fine cellulosic fibers to be dispersed into an aqueous phase for\nfurther treatment. The resulting cellulose suspensions need to be pressurized\nand pumped into and out of various processing vessels without allowing the\ndevelopment of flow instabilities that are typically associated with the\ndemixing, i.e., the segregation of the cellulosic biomass from the aqueous\nphase. Here, it is demonstrated that the use of a gelation agent, hydroxypropyl\nguar gum (HPG) at the relatively low concentration of 0.5 wt% significantly\naffects the development of viscoelastic material functions of cellulosic\nsuspensions, and improves the dispersive mixing of the cellulose fibers within\nthe aqueous phase. This results in the reduction of the flow instabilities and\nassociated demixing effects that are ubiquitously observed during the\npressurization of cellulosic suspensions in Poiseuille and compressive squeeze\nflows."
    },
    {
        "anchor": "Modeling ionic flow between small targets: insights from diffusion and\n  electro-diffusion theory: The flow of ions through permeable channels causes voltage drop in\nphysiological nanodomains such as synapses, dendrites and dendritic spines, and\nother protrusions. How the voltage changes around channels in these nanodomains\nhas remained poorly studied. We focus this book chapter on summarizing recent\nefforts in computing the steady-state current, voltage and ionic concentration\ndistributions based on the Poisson-Nernst-Planck equations as a model of\nelectro-diffusion. We first consider the spatial distribution of an uncharged\nparticle density and derive asymptotic formulas for the concentration\ndifference by solving the Laplace's equation with mixed boundary conditions. We\nstudy a constant particles injection rate modeled by a Neumann flux condition\nat a channel represented by a small boundary target, while the injected\nparticles can exit at one or several narrow patches. We then discuss the case\nof two species (positive and negative charges) and take into account motions\ndue to both concentration and electrochemical gradients. The voltage resulting\nfrom charge interactions is calculated by solving the Poisson's equation. We\nshow how deep an influx diffusion propagates inside a nanodomain, for\npopulations of both uncharged and charged particles. We estimate the\nconcentration and voltage changes in relations with geometrical parameters and\nquantify the impact of membrane curvature.",
        "positive": "Role of Nanoscale Interfacial Proximity in Contact Freezing in Water: Contact freezing is a mode of atmospheric ice nucleation in which a collision\nbetween a dry ice nucleating particle (INP) and a water droplet results in\nconsiderably faster heterogeneous nucleation. The molecular mechanism of such\nenhancement is, however, still a mystery. While earlier studies had attributed\nit to collision-induced transient perturbations, recent experiments point to\nthe pivotal role of nanoscale proximity of the INP and the free interface. By\nsimulating heterogeneous nucleation of ice within INP-supported nanofilms of\ntwo model water-like tetrahedral liquids, we demonstrate that such nanoscale\nproximity is sufficient for inducing rate increases commensurate with those\nobserved in contact freezing experiments, but only if the free interface has a\ntendency to enhance homogeneous nucleation. Water is suspected of possessing\nthis latter property, known as surface freezing propensity. Our findings\ntherefore establish a connection between surface freezing propensity and\nkinetic enhancement during contact nucleation. We also observe that faster\nnucleation proceeds through a mechanism markedly distinct from classical\nheterogeneous nucleation, involving the formation of hourglass-shaped\ncrystalline nuclei that conceive at either interface, and that have a lower\nfree energy of formation due to the nanoscale proximity of the interfaces and\nthe modulation of the free interfacial structure by the INP. In addition to\nproviding valuable insights into the physics of contact nucleation, our\nfindings can assist in improving the accuracy of heterogeneous nucleation rate\nmeasurements in experiments, and in advancing our understanding of ice\nnucleation on nonuniform surfaces such as organic, polymeric and biological\nmaterials."
    },
    {
        "anchor": "Electric-Double-Layer-Modulation Microscopy: The electric double layer (EDL) formed around charged nanostructures at the\nliquid-solid interface determines their electrochemical activity and influences\ntheir electrical and optical polarizability. We experimentally demonstrate that\nrestructuring of the EDL at the nanoscale can be detected by dark-field\nscattering microscopy. Temporal and spatial characterization of the scattering\nsignal demonstrates that the potentiodynamic optical contrast is proportional\nto the accumulated charge of polarisable ions at the interface and its time\nderivative represents the nanoscale ionic current. The material-specificity of\nthe EDL formation is used in our work as a label-free contrast mechanism to\nimage nanostructures and perform spatially-resolved cyclic voltametry on ion\ncurrent density of a few attoamperes, corresponding to the exchange of only a\nfew hundred ions.",
        "positive": "Viscoelastic materials are most energy efficient when loaded and\n  unloaded at equal rates: Biological springs can be used in nature for energy conservation and\nultra-fast motion. The loading and unloading rates of elastic materials can\nplay an important role in determining how the properties of these springs\naffect movements. We investigate the mechanical energy efficiency of biological\nsprings (American bullfrog plantaris tendons and guinea fowl lateral\ngastrocnemius tendons) and synthetic elastomers. We measure these materials\nunder symmetric rates (equal loading and unloading durations) and asymmetric\nrates (unequal loading and unloading durations) using novel dynamic mechanical\nanalysis measurements. We find that mechanical efficiency is highest at\nsymmetric rates and significantly decreases with a larger degree of asymmetry.\nA generalized 1D Maxwell model with no fitting parameters captures the\nexperimental results based on the independently-characterized linear\nviscoelastic properties of the materials. The model further shows that a\nbroader viscoelastic relaxation spectrum enhances the effect of rate-asymmetry\non efficiency. Overall, our study provides valuable insights into the interplay\nbetween material properties and unloading dynamics in both biological and\nsynthetic elastic systems."
    },
    {
        "anchor": "Dynamic correlation functions in one-dimensional quasi-condensates: We calculate the static and dynamic single-particle correlation functions in\none-dimensional (1D) trapped Bose gases and discuss experimental measurements\nthat can directly probe such correlation functions. Using a quantized\nhydrodynamic theory for the low energy excitations, we calculate both the\nstatic and dynamic single-particle correlation functions for a 1D Bose gas that\nis a phase-fluctuating quasi-condensate. For the static (equal-time)\ncorrelation function, our approximations and results are equivalent to those of\nPetrov, Shlyapnikov and Walraven. The Fourier transform of the static\nsingle-particle correlation function gives the momentum distribution, which can\nbe measured using Doppler-sensitive Bragg scattering experiments on a highly\nelongated Bose gas. We show how a two-photon Raman out-coupling experiment can\nmeasure the characteristic features of the dynamic or time-dependent\nsingle-particle correlation function of a 1D Bose quasi-condensate.",
        "positive": "Conformal order and Poincar$\\rm{\\acute{e}}$-Klein mapping underlying\n  electrostatics-driven inhomogeneity in tethered membranes: Understanding the organization of matter under the long-range electrostatic\nforce is a fundamental problem in multiple fields. In this work, based on the\nelectrically charged tethered membrane model, we reveal regular structures\nunderlying the lowest-energy states of inhomogeneously stretched planar\nlattices by a combination of numerical simulation and analytical geometric\nanalysis. Specifically, we show the conformal order characterized by the\npreserved bond angle in the lattice deformation, and reveal the\nPoincar$\\rm{\\acute{e}}$-Klein mapping underlying the electrostatics-driven\ninhomogeneity. The discovery of the Poincar$\\rm{\\acute{e}}$-Klein mapping,\nwhich connects the Poincar$\\rm{\\acute{e}}$ disk and the Klein disk for the\nhyperbolic plane, implies the connection of long-range electrostatic force and\nhyperbolic geometry. We also discuss lattices with patterned charges of\nopposite signs for modulating in-plane inhomogeneity and even creating 3D\nshapes, which may have a connection to metamaterials design. This work suggests\nthe geometric analysis as a promising approach for elucidating the organization\nof matter under the long-range force."
    },
    {
        "anchor": "Eshelby inclusions in granular matter: theory and simulations: We present a numerical implementation of an active inclusion in a granular\nmaterial submitted to a biaxial test. We discuss the dependence of the response\nto this perturbation on two parameters: the intra-granular friction coefficient\non one hand, the degree of the loading on the other hand. We compare the\nnumerical results to theoretical predictions taking into account the change of\nvolume of the inclusion as well as the anisotropy of the elastic matrix.",
        "positive": "Hydrodynamics of isotropic and liquid crystalline active polymer\n  solutions: We describe the large-scale collective behavior of solutions of polar\nbiofilaments and both stationary and mobile crosslinkers. Both mobile and\nstationary crosslinkers induce filament alignment promoting either polar or\nnematic order. In addition, mobile crosslinkers, such as clusters of motor\nproteins, exchange forces and torques among the filaments and render the\nhomogeneous states unstable via filament bundling. We start from a Smoluchowski\nequation for rigid filaments in solutions, where pairwise crosslink-mediated\ninteractions among the filaments yield translational and rotational currents.\nThe large-scale properties of the system are described in terms of continuum\nequations for filament and motor densities, polarization and alignment tensor\nobtained by coarse-graining the Smoluchovski equation. The possible homogeneous\nand inhomogeneous states of the systems are obtained as stable solutions of the\ndynamical equations and are characterized in terms of experimentally accessible\nparameters. We make contact with work by other authors and show that our model\nallows for an estimate of the various parameters in the hydrodynamic equations\nin terms of physical properties of the crosslinkers."
    },
    {
        "anchor": "Buckling and wrinkling from geometric and energetic viewpoints: We discuss shape profiles emerging in inhomogeneous growth of squeezed\ntissues. Two approaches are used simultaneously: i) conformal embedding of\ntwo-dimensional domain with hyperbolic metrics into the plane, and ii) a pure\nenergetic consideration based on the minimization of the total energy\nfunctional. In the latter case the non-uniformly pre-stressed plate, which\nmodels the inhomogeneous two-dimensional growth, is analyzed in linear regime\nunder small stochastic perturbations. It is explicitly demonstrated that both\napproaches give consistent results for buckling profiles and reveal\nself-similar behavior. We speculate that fractal-like organization of growing\nsqueezed structure has a far-reaching impact on understanding cell\nproliferation in various biological tissues.",
        "positive": "Precipitation induced filament pattern of injected fluid controlled by\n  structured cell: Mixing of two fluids can lead to the formation of a precipitate. If one of\nthe fluids is injected into a confined space filled with the other, a created\nprecipitate disrupts the flow locally and forms complex spatiotemporal\npatterns. The relevance of controlling these patterns has been highlighted in\nthe engineering and geological contexts. Here, we show that such injection\npatterns can be controlled consistently by injection rate and obstacles. Our\nexperimental results revealed filament patterns for high injection and low\nreaction rates, and the injection rate can control the number of active\nfilaments. Furthermore, appropriately spaced obstacles in the cells can\nstraighten the motion of the advancing tip of the filament. A mathematical\nmodel based on a moving boundary adopting the effect of precipitation\nreproduced the phase diagram and the straight motion of filaments in structured\ncells. Our study clarifies the impact of the nonlinear permeability response on\nthe precipitate density and that of the obstacles in the surrounding medium on\nthe motion of the injected fluid with precipitation."
    },
    {
        "anchor": "Vortex Stabilization in Dilute Bose-Einstein Condensate Under Rotation: The stability of a quantized vortex state in Bose-Einstein condensation is\nexamined within Bogoliubov theory for alkali atom gases confined in a harmonic\npotential under forced rotation. By solving the non-linear Bogoliubov equations\ncoupled with the Gross-Pitavskii equation, the elementary excitations and the\ntotal energy of the systems are calculated as a function of rotation velocity.\nThere are two distinct criteria of vortex stability; The position of the\nexcitation energy levels relative to the condensate energy level yields the\nlocal stability criterion, and the total energy relative to that of the\nnon-vortex state yields the global stability criterion. The vortex stability\nphase diagram in the rotation velocity vs the particle density of the system is\nobtained, allowing one to locate the appropriate region to observe the singly\nquantized vortex.",
        "positive": "Experimental observation of sound-mediated stable configurations for\n  polystyrene particles: Here we present an experimental observation of the self-organization effect\nof the polystyrene particles formed by acoustically-induced interaction forces.\nTwo types of stable configurations are observed experimentally: one is\nmechanically equilibrium and featured by nonzero inter-particle separations,\nand the other corresponds to a close-packed assembly, which is formed by strong\nattractions among the aggregated particles. For the former case involving two\nor three particles, the most probable inter-particle separations (counted for\nnumerous independent initial arrangements) agree well with the theoretical\npredictions. For the latter case, the number of the final stable configurations\ngrows with the particle number, and the occurrence probability of each\nconfiguration is interpreted by a simple geometric model."
    },
    {
        "anchor": "Manipulating a single adsorbed DNA for a critical endpoint: We show the existence of a critical endpoint in the phase diagram of\nunzipping of an adsorbed double-stranded (ds) polymer like DNA. The competition\nof base pairing, adsorption and stretching by an external force leads to the\ncritical end point. From exact results, the location of the critical end point\nis determined and its classical nature established.",
        "positive": "Reducing the variance in the translocation times by pre-stretching the\n  polymer: Langevin Dynamics simulations of polymer translocation are performed where\nthe polymer is stretched via two opposing forces applied on the first and last\nmonomer before and during translocation. In this setup, polymer translocation\nis achieved by imposing a bias between the two pulling forces such that there\nis net displacement towards the \\textit{trans}-side. Under the influence of\npre-stretching forces, the elongated polymer ensemble contains less variations\nin conformations compared to an unstretched ensemble. Simulations demonstrate\nthat this reduced spread in initial conformations yields a reduced variation in\ntranslocations times relative to the mean translocation time. This effect is\nexplored for different ratios of the amplitude of thermal fluctuations to\ndriving forces to control for the relative influence of the thermal path\nsampled by the polymer. Since the variance in translocation times is due to\ncontributions coming from sampling both thermal noise and initial\nconformations, our simulations offer independent control over the two main\nsources of noise, and allow us to shed light on how they both contribute to\ntranslocation dynamics. Experimentally relevant conditions are highlighted and\nshown to correspond to a significant decrease in the spread of translocation\ntimes, thus indicating that stretching DNA prior to translocation could assist\nin nanopore-based sequencing and sizing applications."
    },
    {
        "anchor": "Comment on \"Spin-1 aggregation model in one dimension\": M. Girardi and W. Figueiredo have proposed a simple model of aggregation in\none dimension to mimic the self-assembly of amphiphiles in aqueous solution\n[Phys. Rev. E 62, 8344 (2000)]. We point out that interesting results can be\nobtained if a different set of interactions is considered, instead of their\nchoice (the s=1 Ising model).",
        "positive": "Nanometric pitch in modulated structures of twist-bend nematic liquid\n  crystals: The extended Frank elastic energy density is used to investigate the\nexistence of a stable periodically modulate structure that appears as a ground\nstate exhibiting a twist-bend molecular arrangement. For an unbounded sample,\nwe show that the twist-bend nematic phase $N_{TB}$ is characterized by a\nheliconical structure with a pitch in the nano-metric range, in agreement with\nexperimental results. For a sample of finite thickness, we show that the wave\nvector of the stable periodic structure depends not only on the elastic\nparameters but also on the anchoring energy, easy axis direction, and the\nthickness of the sample."
    },
    {
        "anchor": "Viscosity and effective temperature of an active dense system of\n  self-propelled particles: We obtain a nonequilibrium theory for a simple model of a generic class of\nactive dense systems consisting of self-propelled particles with a\nself-propulsion force, $f_0$, and persistence time, $\\tau_p$, of their motion.\nWe consider two models of activity and find the system is characterized by an\nevolving effective temperature $T_{eff}(\\tau)$, defined through a generalized\nfluctuation-dissipation theorem. $T_{eff}(\\tau)$ is equal to the equilibrium\ntemperature at very short time $\\tau$ and saturates to\n$T_{eff}=T_{eff}(\\tau\\to\\infty)$ at long times; The transition time $t_{trans}$\nwhen $T_{eff}(\\tau)$ goes to the long-time limit depends on $\\tau_p$ alone and\n$t_{trans}\\sim \\tau_p^{0.85}$ for both models. $f_0$ reduces the viscosity with\nincreasing activity, $\\tau_p$ on the other hand, may increase or decrease\nviscosity depending on the details of how the activity is included. However, as\na function of $T_{eff}$, viscosity shows the same behavior for different models\nof activity and $\\eta\\sim (T_{eff}-T)^{-\\gamma}$ with $\\gamma=1.74$. Our theory\ngives reasonable agreement when compared with experimental data and is\nconsistent with several experiments on diverse systems.",
        "positive": "Simple approach for calculating the binding free energy of a multivalent\n  particle: We present a simple yet accurate numerical approach to compute the free\nenergy of binding of multivalent objects on a receptor-coated surface. The\nmethod correctly accounts for the fact that one ligand can bind to at most one\nreceptor. The numerical approach is based on a saddle-point approximation to\nthe computation of a complex residue. We compare our theory with the powerful\nValence-Limited Interaction Theory (VLIT) (J. Chem. Phys. 137, 094108(2012), J.\nChem. Phys. 138, 021102(2013)) and find excellent agreement in the regime where\nthat theory is expected to work. However, the present approach even works for\nlow receptor/ligand densities, where VLIT breaks down."
    },
    {
        "anchor": "Machine Learning for Phase Behavior in Active Matter Systems: We demonstrate that deep learning techniques can be used to predict motility\ninduced phase separation (MIPS) in suspensions of active Brownian particles\n(ABPs) by creating a notion of phase at the particle level. Using a fully\nconnected network in conjunction with a graph neural network we use individual\nparticle features to predict to which phase a particle belongs. From this, we\nare able to compute the fraction of dilute particles to determine if the system\nis in the homogeneous dilute, dense, or coexistence region. Our predictions are\ncompared against the MIPS binodal computed from simulation. The strong\nagreement between the two suggests that machine learning provides an effective\nway to determine the phase behavior of ABPs and could prove useful for\ndetermining more complex phase diagrams.",
        "positive": "Experimental characterization of vibrated granular rings: We report an experimental study of the statistical properties of vibrated\ngranular rings. In this system, a linked rod and bead metallic chain in the\nform of a ring is collisionally excited by a vertically oscillating plate. The\ndynamics are driven primarily by inelastic bead-plate collisions and are\nsimultaneously constrained by the rings' physical connectedness. By imaging\nmany instances of the ring configurations, we measure the ensemble averages and\ndistributions of several physical characteristics on the scale of individual\nbeads and composite ring. We study local properties such as inter-bead\nseperation and inter-bonds angles, and global properties such as the radius of\ngyration and center of mass motion. We characterize scaling with respect to the\nsize of the chain."
    },
    {
        "anchor": "Coupling between denaturation and chain conformations in DNA:\n  stretching, bending, torsion and finite size effects: We develop further a statistical model coupling denaturation and chain\nconformations in DNA (Palmeri J, Manghi M and Destainville N 2007 Phys. Rev.\nLett. 99 088103). Our Discrete Helical Wormlike Chain model takes explicitly\ninto account the three elastic degrees of freedom, namely stretching, bending\nand torsion of the polymer. By integrating out these external variables, the\nconformational entropy contributes to bubble nucleation (opening of\nbase-pairs), which sheds light on the DNA melting mechanism. Because the values\nof monomer length, bending and torsional moduli differ significantly in dsDNA\nand ssDNA, these effects are important. Moreover, we explore in this context\nthe role of an additional loop entropy and analyze finite-size effects in an\nexperimental context where polydA-polydT is clamped by two G-C strands, as well\nas for free polymers.",
        "positive": "Jet-induced cratering of a granular surface with application to lunar\n  spaceports: The erosion of lunar soil by rocket exhaust plumes is investigated\nexperimentally. This has identified the diffusion-driven flow in the bulk of\nthe sand as an important but previously unrecognized mechanism for erosion\ndynamics. It has also shown that slow regime cratering is governed by the\nrecirculation of sand in the widening geometry of the crater. Scaling\nrelationships and erosion mechanisms have been characterized in detail for the\nslow regime. The diffusion-driven flow occurs in both slow and fast regime\ncratering. Because diffusion-driven flow had been omitted from the lunar\nerosion theory and from the pressure cratering theory of the Apollo and Viking\nera, those theories cannot be entirely correct."
    },
    {
        "anchor": "Molecular modelling of odd viscoelastic fluids: We consider an active, stochastic microscopic model of particles suspended in\na fluid and show that the coarse-grained description of this model renders odd\nviscoelasticity. The model is made up of odd dumbbells, each featuring a\nrobotic device as the bead, which exhibits a particular torque response. We\nanalytically compute the stress-stress correlator and corroborate the results\nusing molecular dynamics simulations. We also provide a unified analytical\nframework for several experimental and numerical setups designed to elucidate\nodd effects in fluids.",
        "positive": "Strain induced strengthening of soft thermoplastic polyurethanes under\n  cyclic deformation: We investigate the cyclic mechanical behavior in uniaxial tension of three\ndifferent commercial thermoplastic polyurethane elastomers (TPU) often\nconsidered as a sustainable replacement for common filled elastomers. All TPU\nhave similar hard segment contents and linear moduli but sensibly different\nlarge strain properties as shown by X-Ray analysis. Despite these differences,\nwe found a stiffening effect after conditioning in step cyclic loading which\ngreatly differs from the common softening (also referred as Mullins effect)\nobserved in chemically crosslinked filled rubbers. We propose that this\nself-reinforcement is related to the fragmentation of hard domains, naturally\npresent in TPU, in smaller but more numerous sub-units that may act as new\nphysical crosslinking points. The proposed stiffening mechanism is not\ndissimilar to the strain-induced crystallization observed in stretched natural\nrubber, but it presents a persistent nature. In particular, it may cause a\nlocal reinforcement where an inhomogeneous strain field is present, as is the\ncase of a crack propagating in cyclic fatigue, providing a potential\nexplanation for the well-known toughness and wear resistance of TPU"
    },
    {
        "anchor": "Understanding the phase behavior of a proto-biomembrane: The rich thermotropic behavior of lipid bilayers is addressed using\nphenomenological theory informed by many experiments. The most recent\nexperiment not yet addressed by theory has shown that the tilt modulus in DMPC\nlipid bilayers decreases dramatically as the temperature is lowered toward the\nmain transition temperature TM . It is shown that this behavior can be\nunderstood by introducing a simple free energy functional for tilt that couples\nto the area per molecule. This is combined with a chain melting free energy\nfunctional in which the area is the primary order parameter that is the driver\nof the main transition. Satisfactory agreement with experiment is achieved with\nvalues of the model parameters determined by experiments, but the transition is\ndirectly into the gel phase. The theory is then extended to include the\nenigmatic ripple phase by making contact with the most recent experimentally\ndetermined ripple structure.",
        "positive": "Microscopic origins of shear stress in dense fluid-grain mixtures: A numerical model is used to simulate rheometer experiments at constant\nnormal stress on dense suspensions of spheres. The complete model includes\nsphere-sphere contacts using a soft contact approach, short range hydrodynamic\ninteractions defined by frame-invariant expressions of forces and torques in\nthe lubrication approximation, and drag forces resulting from the\nporomechanical coupling computed with the DEM-PFV technique. Series of\nsimulations in which some of the coupling terms are neglected highlight the\nrole of the poromechanical coupling in the transient regimes. They also reveal\nthat the shear component of the lubrication forces, though frequently neglected\nin the literature, has a dominant effect in the volume changes. On the other\nhand, the effects of lubrication torques are much less significant.\n  The bulk shear stress is decomposed into contact stress and hydrodynamic\nstress terms whose dependency on a dimensionless shear rate - the so called\nviscous number $I_v$ - are examined. Both contributions are increasing\nfunctions of $I_v$, contacts contribution dominates at low viscous number\n($I_v<$0.15) whereas lubrication contributions are dominant for $I_v>$ 0.15,\nconsistently with a phenomenological law infered by other authors. Statistics\nof microstructural variables highlight a complex interplay between solid\ncontacts and hydrodynamic interactions. In contrast with a popular idea, the\nresults suggest that lubrication may not necessarily reduce the contribution of\ncontact forces to the bulk shear stress. The proposed model is general and\napplies directly to sheared immersed granular media in which pore pressure\nfeedback plays a key role (triggering of avalanches, liquefaction)."
    },
    {
        "anchor": "Interplay of orientational order and roughness in simulated thin film\n  growth of anisotropically interacting particles: Roughness and orientational order in thin films of anisotropic particles are\ninvestigated using kinetic Monte Carlo simulations on a cubic lattice.\nAnisotropic next-neighbor interactions between the lattice particles were\nchosen to mimic the effects of shape anisotropy in the interactions of disc- or\nrod-like molecules with van-der-Waals attractions. Increasing anisotropy leads\nfirst to a preferred orientation in the film (which is close to the\ncorresponding equilibrium transition) while the qualitative mode of roughness\nevolution (known from isotropic systems) does not change. At strong\nanisotropies, an effective step-edge (Ehrlich-Schwoebel) barrier appears and a\nnon-equilibrium roughening effect is found, accompanied by re-ordering in the\nfilm which can be interpreted as the nucleation and growth of domains of\nlying-down discs or rods. The information on order and roughness is combined\ninto a diagram of dynamic growth modes.",
        "positive": "Electroformation in a flow chamber with solution exchange as a means of\n  preparation of flaccid giant vesicles: A recently described technique (Estes and Mayer, Biochim. Biophys. Acta 1712\n(2005) 152--160) for the preparation of giant unilamellar vesicles (GUVs) in\nsolutions with high ionic strength is examined. By observing a series of\nosmotic swellings followed by vesicle bursts upon a micropipette transfer of a\nsingle POPC GUV from a sucrose solution into an isoosmolar glycerol solution, a\nvalue for the permeability of POPC membrane for glycerol, P = (2.09+/-0.82) x\n10^{-8} m/s, has been obtained. Based on this result, an alternative mechanism\nis proposed for the observed exchange of vesicle interior. With modifications,\nthe method of Estes and Mayer is then applied to preparation of flaccid GUVs."
    },
    {
        "anchor": "Quantized Hydrodynamic Theory of One-Dimensional Hard Core Bosons: We present a quantized hydrodynamic theory and its applications of\none-dimensional hard-core bosons in a harmonic trap. Quantizing the Hamiltonian\nof a trapped hard-core bosons and diagonalize it in terms of the phase and\ndensity fluctuations associated with the Bose field operator. As an\napplications, we calculate discrete energy spectrum, dynamic structure factor,\nmomentum transferred by a two-photon Bragg pulse, single-particle density\nmatrix, momentum distribution, and two-particle correlation function. The\ndynamic structure factor has multiple peaks due to the discrete nature of the\nenergy spectrum which can be observed by a two-photon Bragg pulse with long\nduration. The coherence length at zero temperature is very small due to the\n\"fermionization\" of the system. We also compute the momentum distributions\nwhich has oscillatory behavior at large momentum. The pair distribution\nfunction shows that there are many deep valleys at various relative separations\nwhich implies shell structure due to the Pauli blocking in real space.",
        "positive": "Electrostatically-Driven Granular Media: Phase Transitions and\n  Coarsening: We report the experimental and theoretical study of electrostatically driven\ngranular material. We show that the charged granular medium undergoes a\nhysteretic first order phase transition from the immobile condensed state\n(granular solid) to a fluidized dilated state (granular gas) with a changing\napplied electric field. In addition we observe a spontaneous precipitation of\ndense clusters from the gas phase and subsequent coarsening - coagulation of\nthese clusters. Molecular dynamics simulations shows qualitative agreement with\nexperimental results."
    },
    {
        "anchor": "Monte Carlo simulations of the L10 long-range order relaxation in\n  dimensionally reduced systems: Monte Carlo simulations have been performed to investigate the relaxation of\nthe L10 long-range order in dimensionally reduced systems. The effect of the\nnumber of (001)-type monatomic layers and of the pair interaction energies on\nthese kinetics has been examined. The vacancy migration energies have been\ndeduced from the Arrhenius plots of the relaxation times. A substantial\nincrease in the migration energy for small film thickness is observed. The\nresults agree with previous Monte Carlo simulations and with recent\nexperimental results in L1_0 thin films and multilayers.",
        "positive": "Increasing the density melts ultrasoft colloidal glasses: We use theory and simulations to investigate the existence of amorphous\nglassy states in ultrasoft colloids. We combine the hyper-netted chain\napproximation with mode-coupling theory to study the dynamic phase diagram of\nsoft repulsive spheres interacting with a Hertzian potential, focusing on low\ntemperatures and large densities. At constant temperature, we find that an\namorphous glassy state is entered upon compression, as in colloidal hard\nspheres, but the glass unexpectedly melts when density increases further. We\nattribute this re-entrant fluid-glass transition to particle softness, and\ncorrelate this behaviour to previously reported anomalies in soft systems, thus\nemphasizing its generality. The predicted fluid-glass-fluid sequence is\nconfirmed numerically."
    },
    {
        "anchor": "Dynamic regimes of hydrodynamically coupled self-propelling particles: We analyze the collective dynamics of self-propelling particles (spps) which\nmove at small Reynolds numbers including the hydrodynamic coupling to the\nsuspending solvent through numerical simulations. The velocity distribution\nfunctions show marked deviations from Gaussian behavior at short times, and the\nmean-square displacement at long times shows a transition from diffusive to\nballistic motion for appropriate driving mechanism at low concentrations. We\ndiscuss the structures the spps form at long times and how they correlate to\ntheir dynamic behavior.",
        "positive": "Pressure Gradients Fail to Predict Diffusio-Osmosis: We present numerical simulations of diffusio-osmotic flow, i.e. the fluid\nflow generated by a concentration gradient along a solid-fluid interface. In\nour study, we compare a number of distinct approaches that have been proposed\nfor computing such flows and compare them with a reference calculation based on\ndirect, non-equilibrium Molecular Dynamics simulations. As alternatives, we\nconsider schemes that compute diffusio-osmotic flow from the gradient of the\nchemical potentials of the constituent species and from the gradient of the\ncomponent of the stress tensor parallel to the interface. We find that the\napproach based on treating chemical potential gradients as external forces\nacting on various species agrees with the direct simulations, thereby\nsupporting the approach of Marbach et al. (J Chem Phys 146, 194701 (2017)). In\ncontrast, an approach based on computing the gradients of the microscopic\npressure tensor does not reproduce the direct non-equilibrium results."
    },
    {
        "anchor": "Optical spectra obtained from amorphous films of rubrene: Evidence for\n  predominance of twisted isomer: In order to investigate the optical properties of rubrene we study the\nvibronic progression of the first absorption band (lowest \\pi -> \\pi^*\ntransition). We analyze the dielectric function of rubrene in solution and thin\nfilms using the displaced harmonic oscillator model and derive all relevant\nparameters of the vibronic progression. The findings are supplemented by\ndensity functional calculations using B3LYP hybrid functionals. Our theoretical\nresults for the molecule in two different conformations, i.e. with a twisted or\nplanar tetracene backbone, are in very good agreement with the experimental\ndata obtained for rubrene in solution and thin films. Moreover, a simulation\nbased on the monomer spectrum and the calculated transition energies of the two\nconformations indicates that the thin film spectrum of rubrene is dominated by\nthe twisted isomer.",
        "positive": "Self-assembly in chains, rings and branches: a single component system\n  with two critical points: We study the interplay between phase separation and self-assembly in chains,\nrings and branched structures in a model of particles with dissimilar patches.\nWe extend Wertheim's first order perturbation theory to include the effects of\nring formation and theoretically investigate the thermodynamics of the model.\nWe find a peculiar shape for the vapor-liquid coexistence, featuring re-entrant\nbehavior in both phases and two critical points, despite the single-component\nnature of the system. The emergence of the lower critical point is caused by\nthe self-assembly of rings taking place in the vapor, generating a phase with\nlower energy and lower entropy than the liquid. Monte Carlo simulations of the\nsame model fully support these unconventional theoretical predictions."
    },
    {
        "anchor": "Deriving a lattice model for neo-Hookean solids from finite element\n  methods: Lattice models are popular methods for simulating deformation of solids by\ndiscretizing continuum structures into spring networks. Despite the simplicity\nand efficiency, most lattice models only rigorously converge to continuum\nmodels for lattices with regular shapes. Here, we derive a lattice model for\nneo-Hookean solids directly from finite element methods (FEM). The proposed\nlattice model can handle complicated geometries and tune the material\ncompressibility without significantly increasing the complexity of the model.\nDistinct lattices are required for irregular structures, where the lattice\nspring stiffness can be pre-calculated with the aid of FEM shape functions.\nMultibody interactions are incorporated to describe the volumetric deformation.\nWe validate the lattice model with benchmark tests using FEM. The simplicity\nand adoptability of the proposed lattice model open possibilities to develop\nnovel numerical platforms for simulating multiphysics and multiscale problems\nvia integrating it with other modeling techniques.",
        "positive": "Quantum Breathers in Electron-phonon Systems: Quantum breathers are studied numerically in several electron-phonon coupled\nfinite chain systems, in which the coupling results in intrinsic nonlinearity\nbut with varying degrees of nonadiabaticity. As for quantum nonlinear lattice\nsystems, we find that quantum breathers can exist as eigenstates of the system\nHamiltonians. Optical responses are calculated as signatures of these coherent\nnonlinear excitations. We propose a new type of quantum nonlinear excitation,\nbreather-excitons, which are bound states of breathers and excitons, whose\nproperties are clarified with a minimal exciton-phonon model."
    },
    {
        "anchor": "Coreless vortex formation in a spinor Bose-Einstein condensate: Coreless vortices were phase-imprinted in a spinor Bose-Einstein condensate.\nThe three-component order parameter of F=1 sodium condensates held in a\nIoffe-Pritchard magnetic trap was manipulated by adiabatically reducing the\nmagnetic bias field along the trap axis to zero. This distributed the\ncondensate population across its three spin states and created a spin texture.\nEach spin state acquired a different phase winding which caused the spin\ncomponents to separate radially.",
        "positive": "Polymer chain stiffness versus excluded volume: A Monte Carlo study of\n  the crossover towards the wormlike chain model: When the local intrinsic stiffness of a polymer chain varies over a wide\nrange, one can observe both a crossover from rigid-rod-like behavior to\n(almost) Gaussian random coils and a further crossover towards self-avoiding\nwalks in good solvents. Using the pruned-enriched Rosenbluth method (PERM) to\nstudy self-avoiding walks of up to $N_b=50000$ steps and variable flexibility,\nthe applicability of the Kratky-Porod model is tested. Evidence for\nnon-exponential decay of the bond-orientational correlations $<\\cos \\theta (s)\n>$ for large distances $s$ along the chain contour is presented, irrespective\nof chain stiffness. For bottle-brush polymers on the other hand, where\nexperimentally stiffness is varied via the length of side-chains, it is shown\nthat these cylindrical brushes (with flexible backbones) are not described by\nthe Kratky-Porod wormlike chain model, since their persistence length is\n(roughly) proportional to their cross-sectional radius, for all conditions of\npractical interest."
    },
    {
        "anchor": "Binary non-additive hard sphere mixtures: Fluid demixing, asymptotic\n  decay of correlations and free fluid interfaces: Using a fundamental measure density functional theory we investigate both\nbulk and inhomogeneous systems of the binary non-additive hard sphere model.\nFor sufficiently large (positive) non-additivity the mixture phase separates\ninto two fluid phases with different compositions. We calculate bulk\nfluid-fluid coexistence curves for a range of size ratios and non-additivity\nparameters and find that they compare well to simulation results from the\nliterature. Using the Ornstein-Zernike equation, we investigate the asymptotic,\nr->infinity, decay of the partial pair correlation functions, g_ij(r). At low\ndensities there occurs a structural crossover in the asymptotic decay between\ntwo different damped oscillatory modes with different wavelengths corresponding\nto the two intra-species hard core diameters. On approaching the fluid-fluid\ncritical point there is Fisher-Widom crossover from exponentially damped\noscillatory to monotonic asymptotic decay. Using the density functional we\ncalculate the density profiles for the planar free fluid-fluid interface\nbetween coexisting fluid phases. We show that the type of asymptotic decay of\ng_ij(r) not only determines the asymptotic decay of the interface profiles, but\nis also relevant for intermediate and even short-ranged behaviour. We also\ndetermine the surface tension of the free fluid interface, finding that it\nincreases with non-additivity, and that on approaching the critical point\nmean-field scaling holds.",
        "positive": "Stability analysis of polarized domains: Polarized ferrofluids, lipid monolayers and magnetic bubbles form domains\nwith deformable boundaries. Stability analysis of these domains depends on a\nfamily of nontrivial integrals. We present a closed form evaluation of these\nintegrals as a combination of Legendre functions. This result allows exact and\nexplicit formulae for stability thresholds and growth rates of individual\nmodes. We also evaluate asymptotic behavior in several interesting limits."
    },
    {
        "anchor": "Colloids with polymer stars: The interaction: We derive the short distance interaction of star polymers in a colloidal\nsolution. We calculate the corresponding force between two stars with arbitrary\nnumbers of legs f_1 and f_2. We show that a simple scaling theory originally\nderived for high f_1, f_2 nicely matches with the results of elaborated\nrenormalization group analysis for f_1 + f_2 =< 6 generalizing and confirming a\nprevious conjecture based only on scaling results for f_1=f_2=1,2.",
        "positive": "Dynamics of interacting Brownian particles: a diagrammatic formulation: We present a diagrammatic formulation of a theory for the time dependence of\ndensity fluctuations in equilibrium systems of interacting Brownian particles.\nTo facilitate derivation of the diagrammatic expansion we introduce a basis\nthat consists of orthogonalized many-particle density fluctuations. We obtain\nan exact hierarchy of equations of motion for time-dependent correlations of\northogonalized density fluctuations. To simplify this hierarchy we neglect\ncontributions to the vertices from higher-order cluster expansion terms. An\niterative solution of the resulting equations can be represented by diagrams\nwith three and four-leg vertices. We analyze the structure of the diagrammatic\nseries for the time-dependent density correlation function and obtain a\ndiagrammatic interpretation of reducible and irreducible memory functions. The\none-loop self-consistent approximation for the latter function coincides with\nmode-coupling approximation for Brownian systems that was derived previously\nusing a projection operator approach."
    },
    {
        "anchor": "Particulate suspension coating of capillary tubes: The displacement of a suspension of particles by an immiscible fluid in a\ncapillary tube or in a porous media is a canonical configuration that finds\napplication in a large number of natural and industrial applications, including\nwater purification, dispersion of colloids and microplastics, coating and\nfunctionalization of tubings. The influence of particles dispersed in the fluid\non the interfacial dynamics and on the properties of the liquid film left\nbehind remain poorly understood. Here, we study the deposition of a coating\nfilm on the walls of a capillary tube induced by the translation of a\nsuspension plug pushed by air. We identify the different deposition regimes as\na function of the translation speed of the plug, the particle size, and the\nvolume fraction of the suspension. The thickness of the coating film is\ncharacterized, and we show that similarly to dip coating, three coating\nregimes, liquid only, heterogeneous, and thick films, are observed. We also\nshow that, at first order, the thickness of films thicker than the particle\ndiameter can be predicted using the effective viscosity of the suspension.\nNevertheless, we also report that for large particles and concentrated\nsuspensions, a shear-induced migration mechanism leads to local variations in\nvolume fraction and modifies the deposited film thickness and composition.",
        "positive": "Triezenberg-Zwanzig expression for the surface tension of a liquid drop: Formulas, analogous to the Triezenberg-Zwanzig expression for the surface\ntension of a planar interface, are presented for the Tolman length, the bending\nrigidity, and the rigidity constant associated with Gaussian curvature. These\nexpressions feature the Ornstein-Zernike direct correlation function and are\nderived from considering the deformation of a liquid drop in the presence of an\nexternal field. This approach is in line with the original analysis by Yvon in\n1948. It is shown that our expressions reduce to previous results from density\nfunctional theory when a mean-field approximation is made for the direct\ncorrelation function. We stress the importance of the form of the external\nfield used and show how the values of the rigidity constants depend on it."
    },
    {
        "anchor": "Modeling Dipolar and Quadrupolar Defect Structures generated by Chiral\n  Islands in Freely-Suspended Liquid Crystal Films: We report a detailed theoretical analysis of novel quadrupolar interactions\nobserved between islands, which are disk-like inclusions of extra layers,\nfloating in thin, freely suspended smectic C liquid crystal films. Strong\ntangential anchoring at the island boundaries result in a strength +1 chiral\ndefect in each island and a companion -1 defect in the film, these forming a\ntopological dipole. While islands of the same handedness form linear chains\nwith the topological dipoles pointing in the same direction, as reported in the\nliterature, islands with different handedness form compact quadrupolar\nstructures with the associated dipoles pointing in opposite directions. The\ninteraction between such heterochiral island--defect pairs is complex, with the\ndefects moving to minimize the director field distortion as the distance\nbetween the islands changes. The details of the inter-island potential and the\ntrajectories of the -1 defects depend strongly on the elastic anisotropy of the\nliquid crystal, which can be modified in the experiments by varying the\nmaterial chirality of the liquid crystal. A Landau model that describes the\nenergetics of freely mobile defects is solved numerically to find equilibrium\nconfigurations for a wide range of parameters.",
        "positive": "Effect of the orientational relaxation on the collective motion of\n  patterns formed by self-propelled particles: We investigate the collective behavior of self-propelled particles (SPPs)\nundergoing competitive processes of pattern formation and rotational relaxation\nof their self-propulsion velocities. In full accordance with previous work, we\nobserve transitions between different steady states of the SPPs caused by the\nintricate interplay among the involved effects of pattern formation,\norientational order, and coupling between the SPP density and orientation\nfields. Based on rigorous analytical and numerical calculations, we prove that\nthe rate of the orientational relaxation of the SPP velocity field is the main\nfactor determining the steady states of the SPP system. Further, we determine\nthe boundaries between domains in the parameter plane that delineate\nqualitatively different resting and moving states. In addition, we analytically\ncalculate the collective velocity $\\vec{v}$ of the SPPs and show that it\nperfectly agrees with our numerical results. We quantitatively demonstrate that\n$\\vec{v}$ does not vanish upon approaching the transition boundary between the\nmoving pattern and homogeneous steady states."
    },
    {
        "anchor": "Fluid breakup during simultaneous two-phase flow through a\n  three-dimensional porous medium: We use confocal microscopy to directly visualize the simultaneous flow of\nboth a wetting and a non-wetting fluid through a model three-dimensional (3D)\nporous medium. We find that, for small flow rates, both fluids flow through\nunchanging, distinct, connected 3D pathways; in stark contrast, at sufficiently\nlarge flow rates, the non-wetting fluid is broken up into discrete ganglia. By\nperforming experiments over a range of flow rates, using fluids of different\nviscosities, and with porous media having different geometries, we show that\nthis transition can be characterized by a state diagram that depends on the\ncapillary numbers of both fluids, suggesting that it is controlled by the\ncompetition between the viscous forces exerted on the flowing oil and the\ncapillary forces at the pore scale. Our results thus help elucidate the diverse\nrange of behaviors that arise in two-phase flow through a 3D porous medium.",
        "positive": "Coupling between long ranged repulsions and short ranged attractions in\n  a colloidal model of zero shear rate viscosity: In this work, we analyzed an isotropic colloidal model incorporating both\nshort-range sticky attractions and long-range electrostatic repulsions. We\ncomputed the zero-shear viscosity and second virial coefficient for a dilute\ncolloidal suspension (i.e., pair interactions only) as a function of the\nstrength of attractions and repulsions. We also developed an analytical\napproximation that allows us to better understand the coupling of the two types\nof interactions. The attractions and repulsions contribute to the zero-shear\nviscosity and second virial coefficient in different ways, leading to cases\nwith the same second virial coefficient but different zero-shear viscosity. The\nanalytical approximation shows that the mechanism of the coupling of\ninteractions is that long-range repulsions can weaken the influence of\nshort-range attractions. This effect alters how repulsions change the\nzero-shear viscosity. Acting independently, both attractions and repulsions\nincrease the viscosity coefficient of the system. However, when both type of\ninteractions are considered together, repulsions can screen the effect of\nattractive interactions thereby reducing the viscosity."
    },
    {
        "anchor": "Coupling between pore formation and phase separation in charged lipid\n  membranes: We investigated the effect of charge on the membrane morphology of giant\nunilamellar vesicles (GUVs) composed of various mixtures containing charged\nlipids. We observed the membrane morphologies by fluorescent and confocal laser\nmicroscopy in lipid mixtures consisting of a neutral unsaturated lipid\n[dioleoylphosphatidylcholine (DOPC)], a neutral saturated lipid\n[dipalmitoylphosphatidylcholine (DPPC)], a charged unsaturated lipid\n[dioleoylphosphatidylglycerol (DOPG$^{\\scriptsize{(-)}}$)], a charged saturated\nlipid [dipalmitoylphosphatidylglycerol (DPPG$^{\\scriptsize{(-)}}$)], and\ncholesterol (Chol). In binary mixtures of neutral DOPC/DPPC and charged\nDOPC/DPPG$^{\\scriptsize{(-)}}$, spherical vesicles were formed. On the other\nhand, pore formation was often observed with GUVs consisting of\nDOPG$^{\\scriptsize{(-)}}$ and DPPC. In a DPPC/DPPG$^{\\scriptsize{(-)}}$/Chol\nternary mixture, pore-formed vesicles were also frequently observed. The\npercentage of pore-formed vesicles increased with the DPPG$^{\\scriptsize{(-)}}$\nconcentration. Moreover, when the head group charges of charged lipids were\nscreened by the addition of salt, pore-formed vesicles were suppressed in both\nthe binary and ternary charged lipid mixtures. We discuss the mechanisms of\npore formation in charged lipid mixtures and the relationship between phase\nseparation and the membrane morphology. Finally, we reproduce the results seen\nin experimental systems by using coarse-grained molecular dynamics simulations.",
        "positive": "Does mesoscopic elasticity control viscous slowing down in glassforming\n  liquids?: The dramatic slowing down of relaxation dynamics of liquids approaching the\nglass transition remains a highly debated problem, where the crux of the puzzle\nresides in the elusive increase of the activation barrier $\\Delta E(T)$ with\ndecreasing temperature $T$. A class of theoretical frameworks -- known as\nelastic models -- attribute this temperature dependence to the variations of\nthe liquid's macroscopic elasticity, quantified by the high-frequency shear\nmodulus $G_\\infty(T)$. While elastic models find some support in a number of\nexperimental studies, these models do not take into account the spatial\nstructures, length scales, and heterogeneity associated with structural\nrelaxation in supercooled liquids. Here, we propose that viscous slowing down\nis controlled by a mesoscopic elastic stiffness $\\kappa(T)$, defined as the\ncharacteristic stiffness of response fields to local dipole forces in the\nliquid's underlying inherent states. First, we show that $\\kappa(T)$ -- which\nis intimately related to the energy and length scales characterizing\nquasilocalized, nonphononic excitations in glasses -- increases more strongly\nwith decreasing $T$ than the macroscopic inherent state shear modulus $G(T)$ in\nseveral computer liquids. Second, we show that the simple relation $\\Delta\nE(T)\\propto\\kappa(T)$ holds remarkably well for some computer liquids, implying\na direct connection between the liquid's underlying mesoscopic elasticity and\nenthalpic energy barriers. On the other hand, we show that for other computer\nliquids, the above relation fails. Finally, we provide strong evidence that\nwhat distinguishes computer liquids in which the $\\Delta E(T) \\propto\n\\kappa(T)$ relation holds, from those in which it does not, is that the latter\nfeature highly granular potential energy landscapes, where many sub-basins\nseparated by low activation barriers exist. [Rest of abstract abridged]"
    },
    {
        "anchor": "The zero-temperature phase diagram of soft-repulsive particle fluids: Effective pair interactions with a soft-repulsive component are a well-known\nfeature of polymer solutions and colloidal suspensions, but they also provide a\nkey to interpret the high-pressure behaviour of simple elements. We have\ncomputed the zero-temperature phase diagram of four different model potentials\nwith various degrees of core softness. Among the reviewed crystal structures,\nthere are also a number of non-Bravais lattices, chosen among those observed in\nreal systems. Some of these crystals are indeed found to be stable for the\nselected potentials. We recognize an apparently universal trend for unbounded\npotentials, going from high- to low-coordinated crystal phases and back upon\nincreasing the pressure. Conversely, a bounded repulsion may lead to\nintermittent appearance of compact structures with compression and no eventual\nsettling down in a specific phase. In both cases, the fluid phase repeatedly\nreenters at intermediate pressures, as suggested by a cell-theory treatment of\nthe solids. These findings are of relevance for soft matter in general, but\nthey also offer fresh insight into the mechanisms subtended to solid\npolymorphism in elemental substances.",
        "positive": "Localization of a multiblock copolymer at a selective interface: Scaling\n  predictions and Monte Carlo verification: We investigate the localization of a hydrophobic - polar (HP) - regular\ncopolymer at a selective solvent-solvent interface with emphasis on the impact\nof block length $M$ on the copolymer behavior. The considerations are based on\nsimple scaling arguments and use the mapping of the problem onto a homopolymer\nadsorption problem. The resulting scaling relations treat the gyration radius\nof the copolymer chain perpendicular and parallel to the interface in terms of\nchain length N and block size M, as well as the selectivity parameter \\chi .\nThe scaling relations differ for the case of weak and strong localization. In\nthe strong localization limit a scaling relation for the lateral diffusion\ncoefficient D is also derived. We implement a dynamic off-lattice Monte - Carlo\nmodel to verify these scaling predictions. For chain lengths in a wide range\n(32 < N < 512) we find good agreement with the scaling predictions."
    },
    {
        "anchor": "Pair diffusion, hydrodynamic interactions, and available volume in dense\n  fluids: We calculate the pair diffusion coefficient D(r) as a function of the\ndistance r between two hard-sphere particles in a dense monodisperse\nsuspension. The distance-dependent pair diffusion coefficient describes the\nhydrodynamic interactions between particles in a fluid that are central to\ntheories of polymer and colloid dynamics. We determine D(r) from the\npropagators (Green's functions) of particle pairs obtained from discontinuous\nmolecular dynamics simulations. At distances exceeding 3 molecular diameters,\nthe calculated pair diffusion coefficients are in excellent agreement with\npredictions from exact macroscopic hydrodynamic theory for large Brownian\nparticles suspended in a solvent bath, as well as the Oseen approximation.\nHowever, the asymptotic 1/r distance dependence of D(r) associated with\nhydrodynamic effects emerges only after the pair distance dynamics has been\nfollowed for relatively long times, indicating non-negligible memory effects in\nthe pair diffusion at short times. Deviations of the calculated D(r) from the\nhydrodynamic models at short distances r reflect the underlying many-body fluid\nstructure, and are found to be correlated to differences in the local available\nvolume. The procedure used here to determine the pair diffusion coefficients\ncan also be used for single-particle diffusion in confinement with spherical\nsymmetry.",
        "positive": "Computational model for the formation of uniform silver spheres by\n  aggregation of nanosize precursors: We present results of computational modeling of the formation of uniform\nspherical silver particles prepared by rapid mixing of ascorbic acid and\nsilver-amine complex solutions in the absence of a dispersing agent. Using an\naccelerated integration scheme to speed up the calculation of particle size\ndistributions in the latter stages, we find that the recently reported\nexperimental results -- some of which are summarized here -- can be modeled\neffectively by the two-stage formation mechanism used previously to model the\npreparation of uniform gold spheres. We treat both the equilibrium\nconcentration of silver atoms and the surface tension of silver precursor\nnanocrystals as free parameters, and find that the experimental reaction time\nscale is fit by a narrow region of this two-parameter space. The kinetic\nparameter required to quantitatively match the final particle size is found to\nbe very close to that used previously in modeling the formation of gold\nparticles, suggesting that similar kinetics governs the aggregation process and\nproviding evidence that the two-stage model of burst nucleation of\nnanocrystalline precursors followed by their aggregation to form the final\ncolloids can be applied to systems both with and without dispersing agents. The\nmodel also reproduced semiquantitatively the effects of solvent viscosity and\ntemperature on the particle preparation."
    },
    {
        "anchor": "On polydispersity and the hard-sphere glass transition: We simulate the dynamics of polydisperse hard spheres at high packing\nfractions, $\\phi$, with an experimentally-realistic particle size distribution\n(PSD) and other commonly-used PSDs such as gaussian or top hat. We find that\nthe mode of kinetic arrest depends on the PSD's shape and not only on its\nvariance. For the experimentally-realistic PSD, the largest particles undergo\nan ideal glass transition at $\\phi\\sim 0.588$ while the smallest particles\nremain mobile. Such species-specific localisation was previously observed only\nin asymmetric binary mixtures. Our findings suggest that the recent observation\nof ergodic behavior up to $\\phi \\sim 0.6$ in a hard-sphere system is not\nevidence for activated dynamics, but an effect of polydispersity.",
        "positive": "Lane formation in gravitationally driven colloid mixtures consisting of\n  up to three different particle sizes: Brownian dynamics simulations are utilized to study segregation phenomena far\nfrom thermodynamic equilibrium. In the present study, we expand upon the\nanalysis of binary colloid mixtures and additionally introduce a third particle\nspecies to further our understanding of colloidal systems. Gravitationally\ndriven, spherical colloids immersed in an implicit solvent are confined in\ntwo-dimensional linear microchannels. The interaction between the colloids is\nmodeled by the Weeks-Chandler-Andersen potential, and the confinement of the\ncolloids is realized by hard walls based on the solution of the Smoluchowski\nequation in half space. In binary and ternary colloidal systems, a difference\nin the driving force is achieved by differing colloid sizes, but fixed mass\ndensity. We observe for both the binary and ternary systems that a driving\nforce difference induces a nonequilibrium phase transition to lanes. For\nternary systems, we study the tendency of lane formation in dependence of the\ndiameter of the medium-sized colloids. Here, we find a sweetspot for lane\nformation in ternary systems. Furthermore, we study the interaction of two\ndifferently sized colloids at the channel walls. Recently, we observed that\ndriven large colloids push smaller colloids to the walls. This results in small\nparticle lanes at the walls at early simulation times. In this work, we\nadditionally find that thin lanes are unstable and dissolve over very long time\nframes. Furthermore, we observe a connection between lane formation and the\nnonuniform distribution of particles along the channel length. This nonuniform\ndistribution occurs either alongside lane formation or in shared lanes (i.e.\nlanes consisting of two colloid types)."
    },
    {
        "anchor": "The order-disorder transition in model lipid bilayers is a first-order\n  hexatic to liquid phase transition: We characterize the order-disorder transition in a model lipid bilayer using\nmolecular dynamics simulations. We find that the ordered phase is hexatic. In\nparticular, in-plane structures possess a finite concentration of 5-7\ndisclination pairs that diffuse throughout the plane of the bilayer, and\nfurther, in-plane structures exhibit long-range orientational order and\nshort-range translational order. In contrast, the disordered phase is liquid.\nThe transition between the two phases is first order. Specifically, it exhibits\nhysteresis, and coexistence exhibits an interface with capillary scaling. The\nlocation of the interface and its spatial fluctuations are analyzed with a\nspatial field constructed from a rotational-invariant for local 6-fold\norientational order. As a result of finite interfacial tension, there\nnecessarily exist associated forces of assembly between membrane-bound solutes\nthat pre-melt the ordered phase.",
        "positive": "Role of Hidden Slow Degrees of Freedom in the Fluctuation Theorem: The validity of the fluctuation theorem for entropy production as deduced\nfrom the observation of trajectories implicitly requires that all slow degrees\nof freedom are accessible. We experimentally investigate the role of hidden\nslow degrees of freedom in a system of two magnetically coupled driven\ncolloidal particles. The apparent entropy production based on the observation\nof just one particle obeys a fluctuation theorem-like symmetry with a slope of\n1 in the short time limit. For longer times, we find a constant slope, but\ndifferent from 1. We present theoretical arguments for a generic linear\nbehavior both for small and large apparent entropy production but not\nnecessarily throughout. By fine-tuning experimental parameters, such an\nintermediate nonlinear behavior can indeed be recovered in our system as well."
    },
    {
        "anchor": "Kinks in the discrete sine-Gordon model with Kac-Baker long-range\n  interactions: We study effects of Kac-Baker long-range dispersive interaction (LRI) between\nparticles on kink properties in the discrete sine-Gordon model. We show that\nthe kink width increases indefinitely as the range of LRI grows only in the\ncase of strong interparticle coupling. On the contrary, the kink becomes\nintrinsically localized if the coupling is under some critical value.\nCorrespondingly, the Peierls-Nabarro barrier vanishes as the range of LRI\nincreases for supercritical values of the coupling but remains finite for\nsubcritical values. We demonstrate that LRI essentially transforms the internal\ndynamics of the kinks, specifically creating their internal localized and\nquasilocalized modes. We also show that moving kinks radiate plane waves due to\nbreak of the Lorentz invariance by LRI.",
        "positive": "Intermittent dry granular flow in a vertical pipe: The intermittent compact flow of glass beads in a vertical glass pipe of\nsmall diameter is studied experimentally by combining particle fraction,\npressure, and air and grain flow rates measurements with a spatio-temporal\nanalysis of the flow. At the onset of the flow, a decompaction front is\nobserved to propagate from the bottom to the top of the tube at a velocity much\nlarger than that of the grains. The blockage front also propagates upwards and\nat a still higher velocity. The decompaction induces a decreasing pressure wave\nstrongly amplified as it propagates upwards towards the top of the tube.\nPressure variations of 3000 Pa or more are detected in this region while\nparticle fraction variations are of the order of 0.02. Grain velocities during\nthe flow period also increase strongly at the top of the tube while the\ncorresponding fraction of total time decreases. A 1D numerical model based on a\nsimple relation between the effective acceleration of the grains and the\nparticle fraction variations reproduces the amplification effect and provides\npredictions for its dependence on the permeability of the packing."
    },
    {
        "anchor": "Metropolis Importance Sampling for Rugged Dynamical Variables: A funnel transformation is introduced, which acts recursively from higher\ntowards lower temperatures. It biases the a-priori probabilities of a canonical\nor generalized ensemble Metropolis simulation, so that they zoom in on the\nglobal energy minimum, if a funnel exists indeed. A first, crude approximation\nto the full transformation, called rugged Metropolis one (RM$_1$), is tested\nfor Met-Enkephalin. At 300$ $K the computational gain is a factor of two and,\ndue to its simplicity, RM$_1$ is well suited to replace the conventional\nMetropolis updating for these kind of systems.",
        "positive": "Voxelization based packing analysis for discrete element simulations of\n  non-spherical particles: A voxelization based post-processing algorithm is proposed to analyze the\npacking of non-spherical particle assemblies simulated using the Discrete\nElement Method. Voxelization of the particle data allows for isolating the\ngeometric features of the granular assembly in various spatial sub-domains (2D\nsurface or 3D region) and investigate the localized packing behaviour.\nAnalyzing the local packing behaviour enables determining con-fined influences\nsuch as the wall-effect, stacking behaviour, local expansion/contraction and\nlocalized loading. The efficacy of the proposed technique to analyze practical\ngranular assemblies is demonstrated through the packing analysis of different\nassemblies of superquadric cubes, superquadric ellipsoidals, and\nmulti-spherical coffee beans."
    },
    {
        "anchor": "Fine Structure of the Radial Breathing Mode in Double-Wall Carbon\n  Nanotubes: The analysis of the Raman scattering cross section of the radial breathing\nmodes of double-wall carbon nanotubes allowed to determine the optical\ntransitions of the inner tubes. The Raman lines are found to cluster into\nspecies with similar resonance behavior. The lowest components of the clusters\ncorrespond well to SDS wrapped HiPco tubes. Each cluster represents one\nparticular inner tube inside different outer tubes and each member of the\nclusters represents one well defined pair of inner and outer tubes. The number\nof components in one cluster increases with decreasing of the inner tube\ndiameter and can be as high as 14.",
        "positive": "Aggregate morphing of self-aligining soft active disks in semi-confined\n  geometry: We study the dependence of alignment and confinement on the aggregate\nmorphology of self-aligning soft disks in a planer box geometry confined along\ny direction. We show that the wall accumulation of aggregates becomes\nnon-uniform upon increase in alignment strength and decrease in box width. The\nheight of these structures is found to be a non-monotonic function of alignment\nstrength. Additionally, we identify two distinct categories of wall aggregates:\nlayered and non-layered structures each exhibiting distinct local structural\nproperties. For non-layered structures, local properties stay nearly constant\nas we move away from the boundary, while for layered structures, they increase\nwith distance from the boundary. Our analysis shows that active pressure\ndifference is a useful indicator for different aggregate morphologies and the\npeaks in the pressure curve are indicative of the average and minimum height of\nthe structure."
    },
    {
        "anchor": "Bounds for effective dielectric permittivity in differential medium\n  approximation: Theoretical approach is proposed to description of dielectric properties of\nmatrix disperse systems which consists of dielectric matrix with embedded in\nmetallic inclusions. On the basis of effective differential medium\napproximation the analytical expressions are obtained for the effective\ndielectric permittivity of the matrix disperse system with inclusions of\nspherical and ellipsoidal shape. The analysis of limits of possible values of\nthe real and imaginary parts of is carried out depending on system parameters.",
        "positive": "Dissolution Dynamics of a Binary Switchable Hydrophilicty Solvent --\n  Polymer Drop into an Acidic Aqueous Phase: Switchable hydrophilicity solvents (SHSs) are solvents defined by their\nability to switch from their hydrophobic form to a hydrophilic form when put in\ncontact with an acidic trigger such as $CO_2$. As a consequence, SHSs qualify\nas promising alternatives to volatile organic compounds during the industrial\nsolvent extraction processes, as greener and inexpensive methods can be applied\nto separate and recover SHSs. Furthermore, because of their less volatile\nnature, SHSs are less flammable and so increase the safety of a larger-scale\nextraction process. In this work, we study the dynamics and in-drop phase\nseparation during the dissolution process of a drop composed of SHS and\npolymer, triggered by an acid in the surrounding aqueous environment. From 70\ndifferent experimental conditions, we found a scaling relationship between the\ndrop dissolution time and initial volume with an overall scaling coefficient\n$\\sim$ 0.53. We quantitatively assessed and found a shorter dissolution time\nrelated with a decrease in pH of the aqueous phase or an increase in initial\npolymer concentration in the drop. Examining the internal state of the drop\nduring the dissolution revealed an in-drop phase separation behavior, resulting\nin a porous morphology of the final polymer particle. Our experimental results\nprovide a microscopic view of the SHS dissolution process from droplets, and\nfindings may help design SHS extraction processes for particle formation from\nemulsions."
    },
    {
        "anchor": "Positive Feedback Regulation Results in Spatial Clustering and Fast\n  Spreading of Active Signaling Molecules on a Cell Membrane: Positive feedback regulation is ubiquitous in cell signaling networks, often\nleading to binary outcomes in response to graded stimuli. However, the role of\nsuch feedbacks in clustering, and in spatial spreading of activated molecules,\nhas come to be appreciated only recently. We focus on the latter, using a\nsimple model developed in the context of Ras activation with competing negative\nand positive feedback mechanisms. We find that positive feedback, in the\npresence of slow diffusion, results in clustering of activated molecules on the\nplasma membrane, and rapid spatial spreading as the front of the cluster\npropagates with a constant velocity (dependent on the feedback strength). The\nadvancing fronts of the clusters of the activated species are rough, with\nscaling consistent with the Kardar-Parisi-Zhang (KPZ) equation in one\ndimension. Our minimal model is general enough to describe signal transduction\nin a wide variety of biological networks where activity in the\nmembrane-proximal region is subject to feedback regulation.",
        "positive": "Hysteresis and Lubrication in Shear Thickening of Cornstarch Suspensions: Aqueous and brine suspensions of corn starch show striking discontinuous\nshear thickening. We have found that a suspension shear-thickened throughout\nmay remain in the jammed thickened state as the strain rate is reduced, but an\nunjamming front may propagate from any unjammed regions. Transient shear\nthickening is observed at strain rates below the thickening threshold, and\nabove it the stress fluctuates. The jammed shear-thickened state may persist to\nlow strain rates, with stresses resembling sliding friction and effective\nviscosity inversely proportional to the strain rate. At the thickening\nthreshold fluid pressure depins the suspension's contact lines on solid\nboundaries so that it slides, shears, dilates and jams. In oil suspensions\nlubrication and complete wetting of confining surfaces eliminate contact line\nforces and prevent jamming and shear thickening, as does addition of immiscible\nliquid surfactant to brine suspensions. Starch suspensions in glycerin-water\nsolutions, viscous but incompletely wetting, have intermediate properties."
    },
    {
        "anchor": "Capillarity-driven thinning dynamics of entangled polymer solutions: We analyze the capillarity-driven thinning dynamics of entangled polymer\nsolutions described by the Doi-Edwards-Marrucci-Grizzuti (DEMG) model and the\nRolie-Poly (RP) model. Both models capture polymer reptation, finite rates of\nchain retraction and finite extensibility of single polymer molecules, while\ndiffering slightly in their final form regarding to the convective constraint\nrelease. We calculate numerically the filament thinning profiles predicted by\nthe two models with realistic entanglement densities, assuming cylindrical\nfilament shapes and no fluid inertia. Both results reveal an early\ntube-reorientation regime, followed by a brief intermediate elasto-capillary\nregime, and finally a finite-extensibility regime close to the pinch-off\nsingularity. The results presented in this work reveal two critical features in\nthe transient extensional rheology of entangled polymer solutions that have\nbeen reported from previous experimental studies, but are poorly described by\nthe widely-used FENE-P model. First, the relaxation time obtained from\ncapillary breakup extensional rheometry is notably smaller than that from\nsteady-shear rheometry. Their ratio can be expressed as a universal function of\nthe entanglement state and the polymer concentration, which agrees well with\nthe experimental data for a range of entangled polymer solutions. Second, the\nfilament thinning dynamics at sufficiently high polymer concentrations are\ngoverned by the tube reorientation at intermediate strain-rates, and the\napparent extensional viscosity shows a noticeably rate-thinning response. We\nfinally evaluate the filament thinning dynamics of aqueous polyethylene oxide\nsolutions (1 MDa) over dilute and entangled regimes. As the concentration\nincreases, the profiles deviate from the well-studied exponential-thinning\ntrends beyond the entangled threshold, becoming increasingly power-law in\ncharacter.",
        "positive": "Mechanical Behaviour of Glasses and Amorphous Materials: A wide range of materials can exist in microscopically disordered solid\nforms, referred to as amorphous solids or glasses. Such materials -- oxide\nglasses and metallic glasses, to polymer glasses, and soft solids such as\ncolloidal glasses, emulsions and granular packings -- are useful as structural\nmaterials in a variety of contexts. Their deformation and flow behaviour is\nrelevant for many others. Apart from fundamental questions associated with the\nformation of these solids, comprehending their mechanical behaviour is thus of\ninterest, and of significance for their use as materials. In particular, the\nnature of plasticity and yielding behaviour in amorphous solids has been\nactively investigated. Different amorphous solids exhibit behaviour that is\napparently diverse and qualitatively different from those of crystalline\nmaterials. A goal of recent investigations has been to comprehend the unifying\ncharacteristics of amorphous plasticity and to understand the apparent\ndifferences among them. We summarise some of the recent progress in this\ndirection. We focus on insights obtained from computer simulation studies, and\nin particular those employing oscillatory shear deformation of model glasses."
    },
    {
        "anchor": "Effect of polydispersity, bimodality and aspect ratio on the phase\n  behavior of colloidal platelet suspensions: We use a Fundamental-Measure density functional for hard board-like\npolydisperse particles, in the restricted-orientation approximation, to explain\nthe phase behaviour of platelet colloidal suspensions studied in recent\nexperiments. In particular, we focus our attention on the behavior of the total\npacking fraction of the mixture, $\\eta$, in the region of two-phase\nisotropic-nematic coexistence as a function of mean aspect ratio,\npolydispersity and fraction of total volume $\\gamma$ occupied by the nematic\nphase. In our model, platelets are polydisperse in the square section, of side\nlength $\\sigma$, but have constant thickness $L$ (and aspect ratio\n$\\kappa\\equiv L/<\\sigma><1$, with $<\\sigma>$ the mean side length). Good\nagreement between our theory and recent experiments is obtained by mapping the\nreal system onto an effective one, with excluded volume interactions but with\nthicker particles (due to the presence of long-ranged repulsive interactions\nbetween platelets). The effect of polydispersity in both shape and particle\nsize has been taken into account by using a size distribution function with an\neffective mean-square deviation that depends on both polydispersities. We also\nshow that the bimodality of the size distribution function is required to\ncorrectly describe the huge two-phase coexistence gap and the nonlinearity of\nthe function $\\gamma(\\eta)$, two important features that these colloidal\nsuspensions exhibit.",
        "positive": "Learning hidden elasticity with deep neural networks: We introduce a de novo elastography method to learn the elasticity of solids\nfrom measured strains. The deep neural network in our new method is supervised\nby the theory of elasticity and does not require labeled data for training.\nResults show that the proposed method can learn the hidden elasticity of solids\naccurately and is robust when it comes to noisy and missing measurements. A\nprobable elasticity distribution for areas without measurements may also be\nreconstructed by the neural network based on the elasticity distribution in\nnearby regions. The neural network learns the hidden elasticity of solids as a\nfunction of positions and thus it can generate elasticity images with an\narbitrary resolution. This feature is applied to create super-resolution\nelasticity images in this study. We demonstrate that the neural network can\nalso learn the hidden physics when strain and elasticity distributions are both\ngiven. The proposed method has various unique features and can be applied to a\nbroad range of elastography applications."
    },
    {
        "anchor": "Yukawa particles confined in a channel and subject to a periodic\n  potential: ground state and normal modes: We consider a classical system of two-dimensional (2D) charged particles,\nwhich interact through a repulsive Yukawa potential $exp(-r/\\lambda)/r$,\nconfined in a parabolic channel which limits the motion of the particles in the\n$y$-direction. Along the $x$-direction, the particles are also subject to a\nperiodic potential substrate. The ground state configurations and the normal\nmode spectra of the system are obtained as function of the periodicity and\nstrength of the periodic potential ($V_0$), and density. An interesting set of\ntunable ground state configurations are found, with first and second order\nstructural transitions between them. A magic configuration with particles\naligned in each minimum of the periodic potential is obtained for V_0 larger\nthan some critical value which has a power law dependence on the density. The\nphonon spectrum of different configurations were also calculated. A\nlocalization of the modes into a small frequency interval is observed for a\nsufficient strength of the periodic potential. A tunable band-gap is found as a\nfunction of $V_0$. This model system can be viewed as a generalization of the\nFrenkel and Kontorova model.",
        "positive": "Surfing or sliding: the act of naming and its implications: Reply to Kov\\'acs et al."
    },
    {
        "anchor": "Critical Fluctuations in Polymer Solutions: Crossover from Criticality\n  to Tricriticality: Critical fluctuations in fluids and fluid mixtures yield a nonanalytic\nasymptotic Ising-like critical thermodynamic behavior in terms of power laws\nwith universal exponents. In polymer solutions, the amplitudes of these power\nlaws depend on the degree of polymerization. Nonasymptotic behavior (upon the\ndeparture from the critical point) is particularly interesting in the case of\npolymer solutions, where it is governed by a competition between the\ncorrelation length of the critical fluctuations and the radius of gyration of\nthe polymer molecules. If the correlation length is the dominant length scale,\nIsing-like critical behavior is observed. If, however, the radius of gyration\nexceeds the correlation length, tricritical behavior with mean-field critical\nexponents is observed. The Ising-like critical region shrinks with the increase\nof the polymer molecular weight. In the limit of an infinite degree of\npolymerization, the Ising-like critical region vanishes, yielding to\ntheta-point tricriticality.",
        "positive": "Weakly nonlinear rheology of transiently crosslinked biopolymer gels: Recent experimental investigations have revealed a non-Maxwellian absorption\npattern in the rheological spectra of actin gels, which was interpreted in\nterms of transient bonds. Here we examine the consequences of reversible\ncrosslinking on the apparent linear spectra of biopolymer solutions\ntheoretically. For a schematic model consisting of a reversibly crosslinked\npower-law fluid we obtain a simple analytical prediction for the position of\nthe absorption peak, which is backed up by a numerical evaluation of the\ninelastic glassy wormlike chain model. This establishes bond breaking as a\nnonlinear non-equilibrium effect that can already be significant for very small\ndriving amplitudes. Our results may be useful for inferring binding affinities\nand reaction rates of biochemical crosslinkers from rheological measurements of\n{\\it in-vitro} reconstituted cytoskeletal gels."
    },
    {
        "anchor": "Coefficient of restitution for viscoelastic disks: The dissipative collision of two identical viscoelastic disks is studied. By\nusing a known law for the elastic part of the interaction force and the\nviscoelastic damping model an analytical solution for the coefficient of\nrestitution shall be given. The coefficient of restitution depends\nsignificantly on the impact velocity. It approaches one for small velocities\nand decreases for increasing velocities.",
        "positive": "Splay and tilt energy of bipolar lipid membranes: Archaea organisms are able to survive in extremely aggressive environment. It\nis thought that such resistance, at least, in part is sustained by unique\nproperties of archaea membrane. The membrane consists of so called bolalipids,\nwhich has two polar heads joined by two hydrocarbon chains. Thus bolalipids can\nexist in two conformations: i) polar heads are located at different sides of\nbolalipid layer, so called, O-shape; ii) polar heads are located at the same\nside of the layer, so called, U-shape. Both polar heads and chains are\nchemically different from those for conventional lipids. In the present study\nwe develop basis for theory of elasticity of bolalipid membranes. Deformations\nof splay, tilt and Gaussian curvature are considered. We show that energetic\ncontributions of tilt deformation from two surfaces of bolalipid layer are\nadditive, as well as Gaussian curvature, while splay deformations yield a\ncross-term. The presence of U-shapes is taken into account in terms of the\nlayer spontaneous curvature. Estimation of tilt modulus and possible\nexperiments allowing to measure splay moduli are described."
    },
    {
        "anchor": "Hysteretic Optimization For Spin Glasses: The recently proposed Hysteretic Optimization (HO) procedure is applied to\nthe 1D Ising spin chain with long range interactions. To study its\neffectiveness, the quality of ground state energies found as a function of the\ndistance dependence exponent, $\\sigma$, is assessed. It is found that the\ntransition from an infinite-range to a long-range interaction at $\\sigma=0.5$\nis accompanied by a sharp decrease in the performance . The transition is\nsignaled by a change in the scaling behavior of the average avalanche size\nobserved during the hysteresis process. This indicates that HO requires the\nsystem to be infinite-range, with a high degree of interconnectivity between\nvariables leading to large avalanches, in order to function properly. An\nanalysis of the way auto-correlations evolve during the optimization procedure\nconfirm that the search of phase space is less efficient, with the system\nbecoming effectively stuck in suboptimal configurations much earlier. These\nobservations explain the poor performance that HO obtained for the\nEdwards-Anderson spin glass on finite-dimensional lattices, and suggest that\nits usefulness might be limited in many combinatorial optimization problems.",
        "positive": "Elasticity of a DNA chain dotted with bubbles under force: The flexibility and the extension along the direction of the force are shown\nto be related to the bubble number fluctuation and the average number of\nbubbles respectively, when the strands of the DNA are subjected to a force\nalong the same direction, here we call a stretching force. The\nforce-temperature phase diagram shows the existence of a tricritical point\n(TCP), where the first-order force induced zipping transition becomes\ncontinuous. On the other hand, when the forces are being applied in opposite\ndirections, here we call an unzipping force, the transition remains\nfirst-order,with the possibility of vanishing of the low-temperature re-entrant\nphase for a semiflexible DNA. Moreover, we found that the bulk elasticity\nchanges only if an external force penetrates the bound phase and affect the\nbubble states"
    },
    {
        "anchor": "Faraday patterns in Bose-Einstein condensates. Amplitude equation for\n  rolls in the parametrically driven, damped Gross-Pitaevskii equation: The parametrically driven, damped Gross-Pitaevskii equation, which models\nBose-Einstein condensates in which the interatomic s-wave scattering length is\nmodulated in time, is shown to support spatially modulated states in the form\nof rolls. A Landau equation with broken phase symmetry is derived, which\ngoverns the dynamics of the roll amplitude.",
        "positive": "Quantifying the link between local structure and cellular rearrangements\n  using information in models of biological tissues: Machine learning techniques have been used to quantify the relationship\nbetween local structural features and variations in local dynamical activity in\ndisordered glass-forming materials. To date these methods have been applied to\nan array of standard (Arrhenius and super-Arrhenius) glass formers, where work\non \"soft spots\" indicates a connection between the linear vibrational response\nof a configuration and the energy barriers to non-linear deformations. Here we\nstudy the Voronoi model, which takes its inspiration from dense epithelial\nmonolayers and which displays anomalous, sub-Arrhenius scaling of its dynamical\nrelaxation time with decreasing temperature. Despite these differences, we find\nthat the likelihood of rearrangements can vary by several orders of magnitude\nwithin the model tissue and extract a local structural quantity, \"softness\"\nthat accurately predicts the temperature-dependence of the relaxation time. We\nuse an information-theoretic measure to quantify the extent to which softness\ndetermines impending topological rearrangements; we find that softness captures\nnearly all of the information about rearrangements that is obtainable from\nstructure, and that this information is large in the solid phase of the model\nand decreases rapidly as state variables are varied into the fluid phase."
    },
    {
        "anchor": "Elasto-viscoplastic Spreading: from Plastocapillarity to\n  Elastocapillarity: We study the spreading of elastoviscoplastic (EVP) droplets under surface\ntension effects. The non- Newtonian material flows like a viscoelastic liquid\nabove the yield stress and behaves like a viscoelastic solid below it. Hence,\nthe droplet initially flows under surface tension forces but eventually reaches\na final equilibrium shape when the stress everywhere inside the droplet falls\nbelow the resisting rheological stresses. We use numerical simulations and\ncombine Volume-of-Fluid (VOF) method and an EVP constitutive model to\nsystematically study the dynamics of spreading and the final shape of the\ndroplets. The spreading process examined in this study finds applications in\ncoating, droplet-based inkjet printing, and 3D printing, where complex fluids\nsuch as paints, thermoplastic filaments, or bio-inks are deposited onto\nsurfaces. Additionally, the computational framework enables the study of a wide\nrange of multiphase interfacial phenomena, from elastocapillarity to\nplastocapillarity.",
        "positive": "Computational probes of molecular motion in the Lewis and Whanstrom\n  model for ortho-terphenyl: We use molecular dynamics simulations to investigate translational and\nrotational diffusion in a rigid three-site model of the fragile glass former\northo-terphenyl, at 260 K < T < 346 K and ambient pressure. An Einstein\nformulation of rotational motion is presented, which supplements the\ncommonly-used Debye model. The latter is shown to break down at supercooled\ntemperatures as the mechanism of molecular reorientation changes from small\nrandom steps to large infrequent orientational jumps. We find that the model\nsystem exhibits non-Gaussian behavior in translational and rotational motion,\nwhich strengthens upon supercooling. Examination of particle mobility reveals\nspatially heterogeneous dynamics in translation and rotation, with a strong\nspatial correlation between translationally and rotationally mobile particles.\nApplication of the Einstein formalism to the analysis of translation-rotation\ndecoupling results in a trend opposite to that seen in conventional approaches\nbased on the Debye formalism, namely an enhancement in the effective rate of\nrotational motion relative to translation upon supercooling."
    },
    {
        "anchor": "Simulations of Odd Microswimmers: We perform numerical simulations of odd microswimmers consisting of three\nspheres and two odd springs. To describe the hydrodynamic interaction, both the\nOseen-type and the Rotne-Prager-Yamakawa (RPY)-type mobilities are used. For\nthe Oseen-type mobility, the simulation results quantitatively reproduce the\nasymptotic expression of the average velocity. For the RPY-type mobility, on\nthe other hand, the average velocity is smaller than that of the Oseen-type\nmobility and the deviation is more pronounced for larger spheres. We also\nperform simulations of microswimmers having different sphere sizes and show\nthat the average velocity becomes smaller than that of the equal size case. The\nsize of the middle sphere plays an important role in determining the average\nvelocity.",
        "positive": "Theoretical model of efficient phagocytosis driven by curved membrane\n  proteins and active cytoskeleton forces: Phagocytosis is the process of engulfment and internalization of\ncomparatively large particles by the cell, that plays a central role in the\nfunctioning of our immune system. We study the process of phagocytosis by\nconsidering a simplified coarse grained model of a three-dimensional vesicle,\nhaving uniform adhesion interaction with a rigid particle, in the presence of\ncurved membrane proteins and active cytoskeletal forces. Complete engulfment is\nachieved when the bending energy cost of the vesicle is balanced by the gain in\nthe adhesion energy. The presence of curved (convex) proteins reduces the\nbending energy cost by self-organizing with higher density at the highly curved\nleading edge of the engulfing membrane, which forms the circular rim of the\nphagocytic cup that wraps around the particle. This allows the engulfment to\noccur at much smaller adhesion strength. When the curved proteins exert\noutwards protrusive forces, representing actin polymerization, at the leading\nedge, we find that engulfment is achieved more quickly and at lower protein\ndensity. We consider spherical as well as non-spherical particles, and find\nthat non-spherical particles are more difficult to engulf in comparison to the\nspherical particles of the same surface area. For non-spherical particles, the\nengulfment time crucially depends upon the initial orientation of the particles\nwith respect to the vesicle. Our model offers a mechanism for the spontaneous\nself-organization of the actin cytoskeleton at the phagocytic cup, in good\nagreement with recent high-resolution experimental observations."
    },
    {
        "anchor": "Size effects in adhesive contacts of viscoelastic media: Is the maximum force required to detach a rigid sphere from a viscoelastic\nsubstrate dependent on the initial value of the contact radius? Experimental\nand theoretical investigations reported in the literature have given opposite\nresponses. Here, we try to answer the above question by exploiting a fully\ndeterministic model in which adhesive interactions are described by\nLennard-Jones potential and the viscoelastic behaviour with the standard linear\nsolid model. When the approach and retraction phases are performed under\nquasi-static conditions, the substrate behaves as an elastic medium and, as\nexpected, the pull-off force Fpo (i.e., the maximum tensile force) is found to\nbe independent of the maximum contact radius amax reached at the end of\nloading. Size-dependent effects are instead observed (i.e., pull-off force Fpo\nchanges with amax) when transient effects occur as the larger the contact area,\nthe greater the size of the bulk volume involved in the dissipation. Results\nare also discussed in the light of viscoelastic crack Persson's theory, which\nis modified to capture size effects related to amax.",
        "positive": "Dissipation-induced rotation of suspended ferromagnetic nanoparticles: We report the precessional rotation of magnetically isotropic ferromagnetic\nnanoparticles in a viscous liquid that are subjected to a rotating magnetic\nfield. In contrast to magnetically anisotropic nanoparticles, the rotation of\nwhich occurs due to coupling between the magnetic and lattice subsystems\nthrough magnetocrystalline anisotropy, the rotation of isotropic nanoparticles\nis induced only by magnetic dissipation processes. We propose a theory of this\nphenomenon based on a set of equations describing the deterministic magnetic\nand rotational dynamics of such particles. Neglecting inertial effects, we\nsolve these equations analytically, find the magnetization and particle\nprecessions in the steady state, determine the components of the particle\nangular velocity and analyze their dependence on the model parameters. The\npossibility of experimental observation of this phenomenon is also discussed."
    },
    {
        "anchor": "Hydrodynamic length-scale selection and effective viscosity in\n  microswimmer suspensions: A universal characteristic of mesoscale turbulence in active suspensions is\nthe emergence of a typical vortex length scale, distinctly different from the\nscale-invariance of turbulent high-Reynolds number flows. Collective\nlength-scale selection has been observed in bacterial fluids, endothelial\ntissue and active colloides, yet the physical origins of this phenomenon remain\nelusive. Here, we systematically derive an effective fourth-order field theory\nfrom a generic microscopic model that allows us to predict the typical vortex\nsize in microswimmer suspensions. Building on a self-consistent closure\ncondition, the derivation shows that the vortex length scale is determined by\nthe competition between local alignment forces and intermediate-range\nhydrodynamic interactions. Vortex structures found in simulations of the theory\nagree with recent measurements in Bacillus subtilis suspensions. Moreover, our\napproach correctly predicts an effective viscosity enhancement (reduction), as\nreported experimentally for puller (pusher) microorganisms.",
        "positive": "Patchy particles by self-assembly of star copolymers on a spherical\n  substrate: Thomson solutions in a geometric problem with a color constraint: Confinement or geometric frustration is known to alter the structure of soft\nmatter, including copolymeric melts, and can consequently be used to tune\nstructure and properties. Here we investigate the self-assembly of ABC and ABB\n3-miktoarm star copolymers confined to a shell using coarse-grained Dissipative\nParticle Dynamics simulations. In bulk and flat geometries the ABC stars form\nhexagonal tilings, but this is topologically prohibited in a spherical geometry\nwhich normally is alleviated by forming pentagonal tiles. However, the\nmolecular architecture of the ABC stars implies an additional 'color\nconstraint' which only allows even tilings (where all polygons have an even\nnumber of edges) and we study the effect of these simultaneous constraints. We\nfind that both ABC and ABB systems form spherical tiling patterns, the type of\nwhich depends on the radius of the spherical substrate. For small spherical\nsubstrates, all solutions correspond to patterns solving the Thomson problem of\nplacing mobile repulsive electric charges on a sphere. In ABC systems we find\nthree coexisting, possibly different tilings, one in each color, each of them\nsolving the Thomson problem simultaneously. For all except the smallest\nsubstrates, we find competing solutions with seemingly degenerate free energies\nthat occur with different probabilities. Statistically, an observer who is\nblind to the differences between B and C can tell from the structure of the A\ndomains if the system is an ABC or an ABB star copolymer system."
    },
    {
        "anchor": "Modeling diffusion in colloidal suspensions by dynamical density\n  functional theory using fundamental measure theory of hard spheres: We study the dynamics of colloidal suspensions of hard spheres that are\nsubject to Brownian motion in the overdamped limit. We obtain the time\nevolution of the self and distinct parts of the van Hove function by means of\ndynamical density functional theory (DDFT). The free energy model for the hard\nsphere fluid that we use is the very accurate White Bear II version of\nRosenfeld's fundamental measure theory. However, in order to remove\ninteractions within the self part of the van Hove function a non-trivial\nmodification has to be applied to the free energy functional. We compare our\ntheoretical results with data that we obtain from dynamical Monte Carlo\nsimulations and find that the latter are well described by our approach even\nfor colloid packing fractions as large as 40%.",
        "positive": "Dynamics of Counterion Condensation: Using a generalization of the Poisson-Boltzmann equation, dynamics of\ncounterion condensation is studied. For a single charged plate in the presence\nof counterions, it is shown that the approach to equilibrium is diffusive. In\nthe far from equilibrium case of a moving charged plate, a dynamical counterion\ncondensation transition occurs at a critical velocity. The complex dynamic\nbehavior of the counterion cloud is shown to lead to a novel nonlinear\nforce-velocity relation for the moving plate."
    },
    {
        "anchor": "Broadband Coherent Perfect Absorption of Acoustic Waves with Bubble\n  Meta-Screens: A bubble meta-screen is an exceptionally effective and low frequency\nresonator which can be optimized in order to exactly balance the energy\nprovided by radiative process and lost under a viscous mechanism (critical\ncoupling). Under this condition, one can absorb 99.9% of the energy carried by\ntwo phase-matched counter propagating acoustic beams. This phenomenon, called\ncoherent perfect absorption, is here observed with bubbles 75 times smaller\nthan the incident wavelength and is shown to be remarkably broadband. Finally,\ntuning the relative phases of the two beams turns out to be an efficient way to\ncontrol the absorption in the medium.",
        "positive": "On the third- and fourth-order constants of incompressible isotropic\n  elasticity: Consider the constitutive law for an isotropic elastic solid with the\nstrain-energy function expanded up to the fourth order in the strain, and the\nstress up to the third order in the strain. The stress-strain relation can then\nbe inverted to give the strain in terms of the stress with a view to\nconsidering the incompressible limit. For this purpose, use of the logarithmic\nstrain tensor is of particular value. It enables the limiting values of all\nnine fourth-order elastic constants in the incompressible limit to be evaluated\nprecisely and rigorously. In particular, it is explained why the three\nconstants of fourth-order incompressible elasticity $\\mu$, $\\bar{A}$, and $\\bar\nD$ are of the same order of magnitude. Several examples of application of the\nresults follow, including determination of the acoustoelastic coefficients in\nincompressible solids and the limiting values of the coefficients of\nnonlinearity for elastic wave propagation."
    },
    {
        "anchor": "Transverse Waves in Nonlinearly Elastic Solids and the Milne-Pinney (or\n  Ermakov) Equation: We establish a connection between the general equations of nonlinear\nelastodynamics and the nonlinear ordinary differential equation of Pinney\n[Proc. Amer. Math. Soc. 1 (1950) 681]. As a starting point, we use the exact\ntravelling wave solutions of nonlinear elasticity discovered by Carroll [Acta\nMechanica 3 (1967) 167]. The connection provides a method for finding new exact\nand approximate dynamic solutions for neo-Hookean and Mooney-Rivlin solids, and\nfor the general third- and fourth-order elasticity models of incompressible\nsolids.",
        "positive": "Simulating two-dimensional correlation spectroscopies with third-order\n  infrared and fifth-order infrared--Raman processes of liquid water: To investigate the possibility of measuring the intermolecular and\nintramolecular anharmonic coupling of balk water, we calculate third-order\ntwo-dimensional (2D) infrared (IR) spectra and fifth-order 2D IR-IR-Raman-Raman\nspectra expressed in terms of four-body correlation functions of optical\nobservables. For this purpose, a multimode Brownian oscillator model of four\ninteracting anharmonic oscillators strongly coupled to their respective heat\nbaths is employed. The nonlinearity of the system-bath interactions is\nconsidered to describe thermal relaxation and vibrational dephasing. The linear\nand nonlinear spectra are then computed in a non-Markovian and nonperturbative\nregime in a rigorous manner using the discretized hierarchical equations of\nmotion in mixed Liouville-Wigner space (DHEOM-MLWS). The calculated 2D spectra\nfor stretching-bending, bending-librational, stretching-librational, and\nstretching-translational modes consist of various positive and negative peaks\nexhibiting essential details of the intermolecular and intramolecular mode-mode\ninteractions under thermal relaxation and dephasing at finite temperature."
    },
    {
        "anchor": "Forced motion of a cylinder within a liquid-filled elastic tube: This work analyzes the viscous flow and elastic deformation created by the\nforced axial motion of a rigid cylinder within an elastic liquid-filled tube.\nThe examined configuration is relevant to various minimally invasive medical\nprocedures in which slender devices are inserted into fluid-filled biological\nvessels, such as percutaneous revascularization, interventional radiology,\nendoscopies and catheterization. By applying the lubrication approximation,\nthin shell elastic model, as well as scaling analysis and regular and singular\nasymptotic schemes, the problem is examined for small and large deformation\nlimits (relative to the gap between the cylinder and the tube). At the limit of\nlarge deformations, forced insertion of the cylinder is shown to involve three\ndistinct regimes and time-scales: (i) initial shear dominant regime, (ii)\nintermediate regime of dominant fluidic pressure and a propagating\nviscous-peeling front, (iii) late-time quasi-steady flow regime of the fully\npeeled tube. A uniform solution for all regimes is presented for a suddenly\napplied constant force, showing initial deceleration and then acceleration of\nthe inserted cylinder. For the case of forced extraction of the cylinder from\nthe tube, the negative gauge pressure reduces the gap between the cylinder and\nthe tube, increasing viscous resistance or creating friction due to contact of\nthe tube and cylinder. Matched asymptotic schemes are used to calculate the\ndynamics of the near-contact and contact limits. We find that the cylinder\nexits the tube in a finite time for sufficiently small or large forces.\nHowever, for an intermediate range of forces the radial contact creates a\nsteady locking of the cylinder inside the tube.",
        "positive": "Simulation of Particle Size Effect on Dynamic Properties and Fracture of\n  PTFE-W-Al Composites: Recent investigations of the dynamic compressive strength of cold\nisostatically pressed composites of polytetrafluoroethylene (PTFE), tungsten\n(W) and aluminum (Al) powders show significant differences depending on the\nsize of metallic particles. The addition of W increases the density and overall\nstrength of the sample. To investigate relatively large deformations\nmulti-material Eulerian and arbitrary Lagrangian-Eulerian methods, which have\nthe ability to efficiently handle the formation of free surfaces, were used.\nThe calculations indicate that the increased strength of the sample with fine\nmetallic particles is due to the formation of force chains under dynamic\nloading. This phenomenon occurs even at larger porosity of the PTFE matrix in\ncomparison with samples with larger particle size of W and higher density of\nthe PTFE matrix."
    },
    {
        "anchor": "Remixing of a phase separated binary colloidal system with particles of\n  different sizes in an external modulation: We explore phase behaviour of a binary colloidal system under external\nspatially periodic modulation. We perform Monte Carlo simulation on a binary\nmixture of big and small repulsive Lennard-Jones particles with diameter ratio\n1:2. We characterise structure by isotropic and anisotropic pair correlation\nfunction, cluster size distribution, bond angle distribution, order parameter\nand specific heat. We observe demixing of the species in the absence of the\nexternal modulation. However, mixing of the species gets enhanced with\nincreasing potential strength. The de-mixing order parameter shows\ndiscontinuity and the specific heat shows a peak with increasing modulation\nstrength, characterizing a first order phase transition.",
        "positive": "Statistical mechanics of local force dipole responses in computer\n  glasses: Soft quasilocalized modes (QLMs) are universally featured by structural\nglasses quenched from a melt, and are supposedly involved in a number of glassy\nanomalies such as the low temperature scaling of their thermal conductivity and\nspecific heat, and sound attenuation at intermediate frequencies. In computer\nglasses, QLMs may assume the form of harmonic vibrational modes under a narrow\nset of circumstances, however direct access to their full distribution over\nfrequency is hindered by hybridizations of QLMs with other low-frequency modes\n(e.g.~phonons). Previous studies to overcome this issue have demonstrated that\nthe response of a glass to local force dipoles serves as a good proxy for its\nQLMs; we therefore study here the statistical-mechanical properties of the\nresponses to local force dipoles in computer glasses, over a large range of\nglass stabilities and in various spatial dimensions, with the goal of revealing\nproperties of the yet-inaccessible full distribution of QLMs' frequencies. We\nfind that, as opposed to the spatial-dimension-independent universal\ndistribution of QLMs' frequencies $\\omega$ (and, consequently, also of their\nstiffness $\\kappa\\!=\\!\\omega^2$), the distribution of stiffnesses associated\nwith responses to local force dipoles features a (weak) dependence on spatial\ndimension. We rationalize this dependence by introducing a lattice model that\nincorporates both the real-space profiles of QLMs --- associated with\ndimension-dependent long-range elastic fields --- and the universal statistical\nproperties of their frequencies. Finally, we discuss possible connections\nbetween our findings and basic aspects of the glass transition problem, and to\nfinite-size effects in plastic activity of ultrastable glasses."
    },
    {
        "anchor": "Crucial role of side walls for granular surface flows: consequences for\n  the rheology: In this paper we study the steady uniform flows that develop when granular\nmaterial is released from a hopper on top of a static pile in a channel. We\nmore specifically focus on the role of side walls by carrying out experiments\nin setup of different widths, from narrow channels 20 particle diameters wide\nto channels 600 particle diameters wide. Results show that steady flows on pile\nare entirely controlled by side wall effects. A theoretical model, taking into\naccount the wall friction and based on a simple local constitutive law recently\nproposed for other granular flow configurations (GDR MiDi 2004), gives\npredictions in quantitative agreement with the measurements. This result gives\nnew insights in our understanding of free surface granular flows and strongly\nsupports the relevance of the constitutive law proposed.",
        "positive": "General up to next-nearest neighbour elasticity of triangular lattices\n  in three dimensions: We establish the most general form of the discrete elasticity of a 2D\ntriangular lattice embedded in three dimensions, taking into account up to\nnext-nearest neighbour interactions. Besides crystalline system, this is\nrelevant to biological physics (e.g., red blood cell cytoskeleton) and soft\nmatter (e.g., percolating gels, etc.). In order to correctly impose the\nrotational invariance of the bulk terms, it turns out to be necessary to take\ninto account explicitly the elasticity associated with the vertices located at\nthe edges of the lattice. We find that some terms that were suspected in the\nlitterature to violate rotational symmetry are in fact admissible"
    },
    {
        "anchor": "Dynamics of a Tonks-Girardeau gas released from a hard-wall trap: We study the expansion dynamics of a Tonks-Girardeau gas released from a hard\nwall trap. Using the Fermi-Bose map, the density profile is found analytically\nand shown to differ from that one of a classical gas in the microcanonical\nensemble even at macroscopic level, for any observation time larger than a\ncritical time. The relevant time scale arises as a consequence of\nfermionization.",
        "positive": "Quartz Crystal Microbalance frequency response to discrete adsorbates in\n  liquids: Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) has become a\nmajor tool in the analysis of adsorption of nanometric objects, such as\nproteins, viruses, liposomes and inorganic particles from the solution. While\nin vacuum extremely accurate mass measurements are possible, in a liquid phase\nthe quantitative analysis is intricate due to the complex interplay of\nhydrodynamic and adhesion forces, varying with the physicochemical properties\nof adsorbent and the quartz resonator surfaces. In the present paper we dissect\nthe role of hydrodynamics for the analytically tractable scenario of a stiff\ncontact, whereas the adsorbed particles oscillate with the resonator as a whole\nwithout rotation. Under the assumption of the low surface coverage, we\ntheoretically study the excess shear force exerted on the resonator due to\npresence of a single adsorbed particle. The excess shear force has two\ncontributions: (i) the fluid-mediated force due to flow disturbance created by\nthe particle and (ii) the viscous force exerted on the particle by the fluid\nand transmitted to the resonator via contact. We found that for small\nadsorbates, there is mutual cancellation of the above contributions to the\nexcess shear force at the leading order approximation, reducing the overall\neffect of the hydrodynamics to the order-of-magnitude of the inertial force.\nHowever, accurate numerical solution shows that for small particles the viscous\nforce dominates over the inertia force, rendering the standard Sauerbrey model\ninapplicable. These findings indicate that the accurate account of\nhydrodynamics in the analysis of QCM-D response is critical. The resulting\ndimensionless frequency and dissipation shifts and the corresponding acoustic\nratio computed numerically, showing a fair agreement with previously published\nexperimental results at low oscillation frequencies."
    },
    {
        "anchor": "Near the jamming transition of elastic active cells: A sharp-interface\n  approach: We use a sharp interface model for active cells to study the jamming\ntransition point and behavior near it by varying cell concentration, active\nvelocity and elasticity, including a binary mixture of soft and stiff cells. We\ndetermine the jamming transition point, as well as behavior near the\ntransition,including the effective diffusion, and sixfold bond correlations.\nFinally, we expand on previous studies by showing the Voronoi dimensionless\ncell shape can be treated as an order parameter at any concentration.",
        "positive": "A lyotropic ferrocolloid (ferronematic) based on a potassium\n  laurate/1-decanole/water ternary solution: A lyotropic ferrocolloid is synthesized by mixing of a cationic ferrofluid\nand potassium laurate/1-decanol/water ternary solution. Conditions of existence\nof a nematic phase in this mixture, other mesophases, and their phase diagrams\nin the vicinity of the nematic one are obtained and characterized\nquantitatively. Inside of the nematic zone the lyotropic ferrocolloid becomes a\nferronematic, i.e., a liquid crystal with remarkably strong magnetic\nproperties. We found that the pH and the component concentrations dramatically\naffect the amount of magnetic particles stably suspended in a lyotropic\ncarrier. Magnetization and magnetic susceptibility of synthesized ferronematics\nare measured depending on the concentration of dispersed magnetic particles."
    },
    {
        "anchor": "Study of the ST2 model of water close to the liquid-liquid critical\n  point: We perform successive umbrella sampling grand canonical Monte Carlo computer\nsimulations of the original ST2 model of water in the vicinity of the proposed\nliquid-liquid critical point, at temperatures above and below the critical\ntemperature. Our results support the previous work of Y. Liu, A.Z.\nPanagiotopoulos and P.G. Debenedetti [J. Chem. Phys. {\\bf 131}, 104508 (2009)],\nwho provided evidence for the existence and location of the critical point for\nST2 using the Ewald method to evaluate the long-range forces. Our results\ntherefore demonstrate the robustness of the evidence for critical behavior with\nrespect to the treatment of the electrostatic interactions. In addition, we\nverify that the liquid is equilibrated at all densities on the Monte Carlo time\nscale of our simulations, and also that there is no indication of crystal\nformation during our runs. These findings demonstrate that the processes of\nliquid-state relaxation and crystal nucleation are well separated in time.\nTherefore, the bimodal shape of the density of states, and hence the critical\npoint itself, is a purely liquid-state phenomenon that is distinct from the\ncrystal-liquid transition.",
        "positive": "Rheology of Polydisperse non-Spherical Graphite Particles Suspended in\n  Mineral Oil: We study the role of filler concentration and microphysics on the rheology of\npolydisperse flake-graphite particles suspended in Newtonian mineral oil. Under\nsteady shear, our samples exhibit shear thinning and yielding behaviour is\nobserved for volume fractions $\\phi > 0.18$. Time-temperature superposition was\nobserved using an Arrhenius-type horizontal shift factor, giving a flow\nactivation energy that is dependent on the graphite volume fraction, suggesting\nconcentration-dependent contributions to relaxation processes in the\nsuspensions. The flow curves are fitted by a constraint-based model, indicating\nthat the flow behaviour is controlled by frictional and adhesive contacts, with\nthe model suggesting that the adhesive stress is temperature dependent."
    },
    {
        "anchor": "Time-correlation functions for odd Langevin systems: We investigate the statistical properties of fluctuations in active systems\nthat are governed by non-symmetric responses. Both an underdamped Langevin\nsystem with an odd resistance tensor and an overdamped Langevin system with an\nodd elastic tensor are studied. For a system in thermal equilibrium, the\ntime-correlation functions should satisfy time-reversal symmetry and the\nanti-symmetric parts of the correlation functions should vanish. For the odd\nLangevin systems, however, we find that the anti-symmetric parts of the\ntime-correlation functions can exist and that they are proportional to either\nthe odd resistance coefficient or the odd elastic constant. This means that the\ntime-reversal invariance of the correlation functions is broken due to the\npresence of odd responses in active systems. Using the short-time asymptotic\nexpressions of the time-correlation functions, one can estimate an odd elastic\nconstant of an active material such as an enzyme or a motor protein.",
        "positive": "Influence of Sensorial Delay on Clustering and Swarming: We show that sensorial delay alters the collective motion of self-propelling\nagents with aligning interactions: In a two-dimensional Vicsek model, short\ndelays enhance the emergence of clusters and swarms, while long or negative\ndelays prevent their formation. In order to quantify this phenomenon, we\nintroduce a global clustering parameter based on the Voronoi tessellation,\nwhich permits us to efficiently measure the formation of clusters. Thanks to\nits simplicity, sensorial delay might already play a role in the organization\nof living organisms and can provide a powerful tool to engineer and dynamically\ntune the behavior of large ensembles of autonomous robots."
    },
    {
        "anchor": "Theory of semi-flexible polymers: We have mapped the physics of a system of semi-flexible inextensible polymers\nonto a complex Ginzburg-Landau field theory using techniques of functional\nintegration. It is shown in the limit of low number density of monomers in a\nmelt of semi-flexible, inextensible polymers, kept apart by an excluded volume\ninteraction, the radius of gyration scales as N^{nu}, where N is the chain\nlength, and nu = 1, in contrast to the value of nu ~ 0.6 for flexible polymer\nmelts. Using Renormalization Group arguments, we show that the system exhibits\nan infra-red stable fixed point which can be identified as the transition to\nthe entangled state. Experiments to test these calculations are suggested.",
        "positive": "Brownian Motion of Boomerang Colloidal Particles: We investigate the Brownian motion of boomerang colloidal particles confined\nbetween two glass plates. Our experimental observations show that the mean\ndisplacements are biased towards the center of hydrodynamic stress (CoH), and\nthat the mean-square displacements exhibit a crossover from short time faster\nto long time slower diffusion with the short-time diffusion coefficients\ndependent on the points used for tracking. A model based on Langevin theory\nelucidates that these behaviors are ascribed to a superposition of two\ndiffusive modes: the ellipsoidal motion of the CoH and the rotational motion of\nthe tracking point with respect to the CoH."
    },
    {
        "anchor": "Hydrodynamics of Suspensions of Passive and Active Rigid Particles: A\n  Rigid Multiblob Approach: We develop a rigid multiblob method for numerically solving the mobility\nproblem for suspensions of passive and active rigid particles of complex shape\nin Stokes flow in unconfined, partially confined, and fully confined\ngeometries. As in a number of existing methods, we discretize rigid bodies\nusing a collection of minimally-resolved spherical blobs constrained to move as\na rigid body, to arrive at a potentially large linear system of equations for\nthe unknown Lagrange multipliers and rigid-body motions. Here we develop a\nblock-diagonal preconditioner for this linear system and show that a standard\nKrylov solver converges in a modest number of iterations that is essentially\nindependent of the number of particles. For unbounded suspensions and\nsuspensions sedimented against a single no-slip boundary, we rely on existing\nanalytical expressions for the Rotne-Prager tensor combined with a fast\nmultipole method or a direct summation on a Graphical Processing Unit to obtain\nan simple yet efficient and scalable implementation. For fully confined\ndomains, such as periodic suspensions or suspensions confined in slit and\nsquare channels, we extend a recently-developed rigid-body immersed boundary\nmethod to suspensions of freely-moving passive or active rigid particles at\nzero Reynolds number. We demonstrate that the iterative solver for the coupled\nfluid and rigid body equations converges in a bounded number of iterations\nregardless of the system size. We optimize a number of parameters in the\niterative solvers and apply our method to a variety of benchmark problems to\ncarefully assess the accuracy of the rigid multiblob approach as a function of\nthe resolution. We also model the dynamics of colloidal particles studied in\nrecent experiments, such as passive boomerangs in a slit channel, as well as a\npair of non-Brownian active nanorods sedimented against a wall.",
        "positive": "Sensing Translocating Polymers via Induced Magnetic Fields: The requirement to boost the resolution of nanopore-based biosequencing\ndevices necessitates the integration of novel biosensing techniques with\nreduced sensitivity to background noise. In this article, we probe the\nsignatures of translocating polymers in magnetic fields induced by ionic\ncurrents through membrane nanopores. Within the framework of a previously\nintroduced charge transport theory, we evaluate the magnetic field signals\ngenerated by voltage- and pressure-driven DNA translocation events in\nmonovalent salt solutions. Our formalism reveals that in voltage-driven\ntransport, the translocating polymer suppresses the induced magnetic field via\nthe steric blockage of the ion current through the mid-pore. In the case of\npressure-driven transport, the magnetic field reduction by translocation\noriginates from the negative electrokinetic contribution of the anionic DNA\nsurface charges to the streaming current predominantly composed of salt\ncations. The magnitude of the corresponding field signals is located in the\nnano-Tesla range covered by the resolution of the magnetoelectric sensors able\nto detect magnetic fields down to the pico-Tesla range. This suggests that the\nintegration of magnetic field detection techniques into the current\nbiosequencing approaches can complement efficiently the conventional biosensing\nstrategies employing ionic current readouts with high susceptibility to\nbackground noise."
    },
    {
        "anchor": "Rheology of periodically sheared suspensions undergoing\n  reversible-irreversible transition: The rheology of non-colloidal suspensions under cyclic shear is studied\nnumerically. The main findings are a strain amplitude ($\\gamma_0$) dependent\nresponse in the shear stress and second normal stress difference ($N_2$).\nSpecifically, we find a reduced viscosity, an enhanced intracycle shear\nthinning, the onset of a finite $N_2$ and its frequency doubling, all near a\ncritical strain amplitude $\\gamma_c$ that scales with the volume fraction\n$\\phi$ as $\\gamma_c \\sim \\phi^{-2}$. These rheological changes also signify a\nreversible-irreversible transition (RIT), dividing stroboscopic particle\ndynamics into a reversible absorbing phase (for $\\gamma_0<\\gamma_c$) and a\npersistently diffusing phase (for $\\gamma_0>\\gamma_c$). We explain the results\nbased on two flow-induced mechanisms and elucidate their connection in the\ncontext of RIT through the underlying microstructure, which tends towards\nhyperuniformity near $\\gamma_0=\\gamma_c$. Overall, we expect this\ncorrespondence between rheology and emergent dynamics to hold in a wide range\nof settings where structural organizations are dominated by volume exclusions.",
        "positive": "Screening of a macroion by multivalent ions: A new boundary condition\n  for Poisson-Boltzmann equation and charge inversion: Screening of a macroion by multivalent counterions is considered. It is shown\nthat ions form strongly correlated liquid at the macroion surface. Cohesive\nenergy of this liquid leads to strong additional attraction of counterions to\nthe surface. Away from the surface this attraction is taken into account by a\nnew boundary condition for the Poisson-Boltzmann equation. This equation is\nsolved with the new boundary condition for a charged flat surface and a long\ncylinder. For a cylinder Onsager-Manning theory looses its universality so that\napparent charge of the cylinder is smaller than their theory predicts and\ndepends on its bare charge. It can also vanish or change sign."
    },
    {
        "anchor": "Dynamically Slow Processes in Supercooled Water Confined Between\n  Hydrophobic Plates: We study the dynamics of water confined between hydrophobic flat surfaces at\nlow temperature. At different pressures, we observe different behaviors that we\nunderstand in terms of the hydrogen bonds dynamics. At high pressure, the\nformation of the open structure of the hydrogen bond network is inhibited and\nthe surfaces can be rapidly dehydrated by decreasing the temperature. At lower\npressure the rapid ordering of the hydrogen bonds generates heterogeneities\nthat are responsible for strong non-exponential behavior of the correlation\nfunction, but with no strong increase of the correlation time. At very low\npressures, the gradual formation of the hydrogen bond network is responsible\nfor the large increase of the correlation time and, eventually, the dynamical\narrest of the system and of the dehydration process.",
        "positive": "End-effects of strongly charged polyelectrolytes - a molecular dynamics\n  study: We investigate end-effects in the ion distribution around strongly charged,\nflexible polyelectrolytes with a quenched charge distribution by molecular\ndynamics simulations of dilute polyelectrolyte solutions. We take the\ncounterions explicitly into account and calculate the full Coulomb interaction\nvia an Ewald summation method. We find that the free counterions of the\nsolution are distributed in such a way that a fraction of the chain charges is\neffectively neutralized. This in turn leads to an effective charge distribution\nwhich is similar to those found for weakly charged titrating polyelectrolytes\nthat have an annealed charge distribution. The delicate interplay between the\nelectrostatic interactions, the chain conformation and the counterion\ndistribution is studied in detail as a function of different system parameters\nsuch as the chain length Nm, the charge fraction f, the charged particle\ndensity rho, the ionic strength and the solvent quality. Comparisons are made\nwith predictions from a scaling theory."
    },
    {
        "anchor": "Target search of active agents crossing high energy barriers: Target search by active agents in rugged energy landscapes has remained a\nchallenge because standard enhanced sampling methods do not apply to\nirreversible dynamics. We overcome this non-equilibrium rare-event problem by\ndeveloping an algorithm generalizing transition-path sampling to active\nBrownian dynamics. This method is exemplified and benchmarked for a\nparadigmatic two-dimensional potential with a high barrier. We find that even\nin such a simple landscape the structure and kinetics of the ensemble of\ntransition paths change drastically in the presence of activity. Indeed, active\nBrownian particles reach the target more frequently than passive Brownian\nparticles, following longer and counterintuitive search patterns.",
        "positive": "Spontaneous electric-polarization topology in confined ferroelectric\n  nematics: Topological spin and polar textures have fascinated people in different areas\nof physics and technologies. However, the observations are limited in magnetic\nand solid-state ferroelectric systems. Ferroelectric nematic is the first\nliquid-state ferroelectric that would carry many possibilities of spatially\ndistributed polarization fields. Contrary to traditional magnetic or\ncrystalline systems, anisotropic liquid crystal interactions can compete with\nthe polarization counterparts, thereby setting a challenge in understating\ntheir interplays and the resultant topologies. Here, we discover chiral\npolarization meron-like structures during the emergence and growth of quasi-2D\nferroelectric nematic domains, which are visualized by fluorescence confocal\npolarizing microscopy and second harmonic generation microscopies. Such\nmicrometre-scale polarization textures are the modified electric variants of\nthe magnetic merons. Unlike the conventional liquid crystal textures driven\nsolely by the elasticity, the polarization field puts additional topological\nconstraints, e.g., head-to-tail asymmetry, to the systems and results in a\nvariety of previously unidentified polar topological patterns. The chirality\ncan emerge spontaneously in polar textures and can be additionally biased by\nintroducing chiral dopants. An extended mean-field modelling for the\nferroelectric nematics reveals that the polarization strength of systems plays\na dedicated role in determining polarization topology, providing a guide for\nexploring diverse polar textures in strongly-polarized liquid crystals."
    },
    {
        "anchor": "Electrokinetic flows in liquid crystal thin films with fixed anchoring: We study ionic and mass transport in a liquid crystalline fluid film in its\nnematic phase under an applied electrostatic field. Both analytic and numerical\nsolutions are given for some prototypical configurations of interest in\nelectrokinetics: Thin films with spatially nonuniform nematic director that are\neither periodic or comprise a set of isolated disclinations. We present a\nquantitative description of the mechanisms inducing spatial charge separation\nin the nematic, and of the structure and magnitude of the resulting flows. The\nfundamental solutions for the charge distribution and flow velocities induced\nby disclinations of topological charge $m=-1/2, 1/2$ and $1$ are given. These\nsolutions allow the analysis of several designer flows, such as \"pusher\" flows\ncreated by three colinear disclinations, the flow induced by an immersed\nspherical particle (equivalent to an $m=1$ defect) and its accompanying $m=-1$\nhyperbolic hedgehog defect, and the mechanism behind nonlinear ionic mobilities\nwhen the imposed field is perpendicular to the line joining the defects.",
        "positive": "Packing fraction of clusters formed in free-falling granular streams\n  based on flash X-ray radiography: We study the packing fraction of clusters in free-falling streams of\nspherical and irregularly shaped particles using flash X-ray radiography. The\nestimated packing fraction of clusters is low enough to correspond to\ncoordination numbers less than 6. Such coordination numbers in numerical\nsimulations correspond to aggregates that collide and grow without bouncing.\nMoreover, the streams of irregular particles evolved faster and formed clusters\nof larger sizes with lower packing fraction. This result on granular streams\nsuggests that particle shape has a significant effect on the agglomeration\nprocess of granular materials."
    },
    {
        "anchor": "Stability and Dynamics of Crystals and Glasses of Motorized Particles: Many of the large structures of the cell, such as the cytoskeleton, are\nassembled and maintained far from equilibrium. We study the stabilities of\nvarious structures for a simple model of such a far-from-equilibrium organized\nassembly in which spherical particles move under the influence of attached\nmotors. From the variational solutions of the manybody master equation for\nBrownian motion with motorized kicking we obtain a closed equation for the\norder parameter of localization. Thus we obtain the transition criterion for\nlocalization and stability limits for the crystalline phase and frozen\namorphous structures of motorized particles. The theory also allows an estimate\nof nonequilibrium effective temperatures characterizing the response and\nfluctuations of motorized crystals and glasses.",
        "positive": "The Invalidity of the Laplace Law for Biological Vessels and of\n  Estimating Elastic Modulus from Total Stress vs. Strain: a New Practical\n  Method: The quantification of the stiffness of tubular biological structures is often\nobtained, both in vivo and in vitro, as the slope of total transmural hoop\nstress plotted against hoop strain. Total hoop stress is typically estimated\nusing the \"Laplace law.\" We show that this procedure is fundamentally flawed\nfor two reasons: Firstly, the Laplace law predicts total stress incorrectly for\nbiological vessels. Furthermore, because muscle and other biological tissue are\nclosely volume-preserving, quantifications of elastic modulus require the\nremoval of the contribution to total stress from incompressibility. We show\nthat this hydrostatic contribution to total stress has a strong\nmaterial-dependent nonlinear response to deformation that is difficult to\npredict or measure. To address this difficulty, we propose a new practical\nmethod to estimate a mechanically viable modulus of elasticity that can be\napplied both in vivo and in vitro using the same measurements as current\nmethods, with care taken to record the reference state. To be insensitive to\nincompressibility, our method is based on shear stress rather than hoop stress,\nand provides a true measure of the elastic response without application of the\nLaplace law. We demonstrate the accuracy of our method using a mathematical\nmodel of tube inflation with multiple constitutive models. We also re-analyze\nan in vivo study from the gastro-intestinal literature that applied the\nstandard approach and concluded that a drug-induced change in elastic modulus\ndepended on the protocol used to distend the esophageal lumen. Our new method\nremoves this protocol-dependent inconsistency in the previous result."
    },
    {
        "anchor": "How Influenza's Spike Motor Works: While often believed to be a passive agent that merely exploits its host's\nmetabolism, influenza virus has recently been shown to actively move across\nglycan-coated surfaces. This form of enzymatically driven surface motility is\ncurrently not well understood and has been loosely linked to burnt-bridge\nBrownian ratchet mechanisms. Starting from known properties of influenza's\nspike proteins, we develop a physical model that quantitatively describes the\nobserved motility. It predicts a collectively emerging dynamics of spike\nproteins and surface bound ligands that combined with the virus' geometry give\nrise to a self-organized rolling propulsion. We show that in contrast to a\nBrownian ratchet, the rotary spike drive is not fluctuation driven but operates\noptimally as a macroscopic engine in the deterministic regime. The mechanism\nalso applies to relatives of influenza and to man-made analogues like\nDNA-monowheels and should give guidelines for their optimization.",
        "positive": "Local and global dynamics in polypropylene glycol / silica composites: The local segmental and global dynamics of a series of polypropylene glycol /\nsilica nanocomposites were studied using rheometry and mechanical and\ndielectric spectroscopies. The particles cause substantial changes in the\nrheology, including higher viscosities that become non-Newtonian and the\nappearance of stress overshoots in the transient shear viscosity. However, no\nchange was observed in the mean relaxation times for either the segmental or\nnormal mode dynamics measured dielectrically. This absence of an effect of the\nparticles is due to masking of the interfacial response by polymer chains\nremote from the particles. When the unattached polymer was extracted to isolate\nthe interfacial material, very large reductions in the relaxation times were\nmeasured. This speeding up of the dynamics is due in part to the reduced\ndensity at the interface, presumably a consequence of poorer packing of\ntethered chains. In addition, binding of the ether oxygens of the polypropylene\nglycol chains truncates the normal mode, which shifts the corresponding\nrelaxation peak to higher frequencies."
    },
    {
        "anchor": "A microscopic view of accelerated dynamics in deformed polymer glasses: A molecular level analysis of segmental trajectories obtained from molecular\ndynamics simulations is used to obtain the full relaxation time spectrum in\naging polymer glasses subject to three different deformation protocols. As in\nexperiments, dynamics can be accelerated by several orders of magnitude, and a\nnarrowing of the distribution of relaxation times during creep is directly\nobserved. Additionally, the acceleration factor describing the transformation\nof the relaxation time distributions is computed and found to obey a universal\ndependence on the global strain, independent of age and deformation protocol.",
        "positive": "Behavior of active filaments near solid-boundary under linear shear flow: The steady-state behavior of a dilute suspension of self-propelled filaments\nconfined between planar walls subjected to the Couette-flow is reported herein.\nThe effect of hydrodynamics has been taken into account using a mesoscale\nsimulation approach. We present a detailed analysis of positional and angular\nprobability distributions of filaments with varying propulsive force and\nshear-flow. Distribution of centre-of-mass of the filament shows adsorption\nnear the surfaces, which diminishes with the flow. The excess density of\nfilaments decreases with Weissenberg number as $Wi^{-\\beta}$ with an exponent\n$\\beta \\approx 0.8$, in the intermediate shear range ($1 < Wi < 30$). The\nangular orientational moment also decreases near the wall as $Wi^{-\\delta}$\nwith $\\delta \\approx 1/5$; the variation in orientational moment near the wall\nis relatively slower than the bulk. It shows a strong dependence on the\npropulsive force near the wall, and it varies as $Pe^{-1/3}$ for large $Pe\\ge\n1$. The active filament shows orientational preference with flow near the\nsurfaces, which splits into upstream and downstream swimming. The population\nsplitting from a unimodal (propulsive force dominated regime) to bimodal phase\n(shear dominated regime) is identified in the parameter space of propulsive\nforce and shear flow."
    },
    {
        "anchor": "Bose-Einstein Condensation of Trapped Atomic Gases: This article reviews recent investigations on the phenomenon of Bose-Einstein\ncondensation of dilute gases. Since the experimental observation of quantum\ndegeneracy in atomic gases, the research activity in the field of coherent\nmatter-waves literally exploded. The present topical review aims to give an\nintroduction into the thermodynamics of Bose-Einstein condensation, a general\noverview over experimental techniques and investigations, and a theoretical\nfoundation for the description of bosonic many-body quantum systems.",
        "positive": "Conformational degrees of freedom and stability of splay-bend ordering\n  in the limit of a very strong planar anchoring: We study the self-organization of flexible planar trimer particles on a\nstructureless surface. The molecules are made up of two mesogenic units linked\nby a spacer, all of which are modeled as hard needles of the same length. Each\nmolecule can dynamically adopt two conformational states: an achiral\nbent-shaped (cis-) and a chiral zigzag (trans-) one.\n  Using constant pressure Monte Carlo simulations and Onsager-type density\nfunctional theory (DFT), we show that the system consisting of these molecules\nexhibits a rich spectrum of (quasi-)liquid crystalline phases. The most\ninteresting observation is the identification of stable smectic splay-bend\n($S_{SB}$) and chiral smectic A ($S_A^*$) phases. The $S_{SB}$ phase is also\nstable in the limit, where only cis-conformers are allowed. The second phase\noccupying a considerable portion of the phase diagram is $S_A^*$ with chiral\nlayers, where the chirality of the neighboring layers is of opposite sign. The\nstudy of the average fractions of the trans- and cis-conformers in various\nphases shows that while in the isotropic phase all fractions are equally\npopulated, the $S_A^*$ phase is dominated by chiral conformers (zigzag), but\nthe achiral conformers win in the smectic splay-bend phase. To clarify the\npossibility of stabilization of the nematic splay bend ($N_{SB}$) phase for\ntrimers, the free energy of the $N_{SB}$ and $S_{SB}$ phases is calculated\nwithin DFT for the cis-conformers, for densities where simulations show stable\n$S_{SB}$. It turns out that the $N_{SB}$ phase is unstable away from the phase\ntransition to the nematic phase, and its free energy is always higher than that\nof $S_{SB}$, down to the transition to the nematic phase, although the\ndifference in free energies becomes extremely small when approaching the\ntransition."
    },
    {
        "anchor": "Numerical analysis of impact processes of granular jets: The rheology of a three-dimensional granular jet during an impact is\ninvestigated numerically. The cone-like scattering pattern and the sheet-like\npattern observed in an experiment [X. Cheng, et al. Phys. Rev. Lett. 99, 188001\n(2007)] can be reproduced through our calculation. We discuss the constitutive\nequation for granular jet impact in terms of our simulation. From the analysis\nof an effective friction constant, which is the ratio between the shear stress\nand the pressure the assumption of the zero yield stress would be natural in\nour setup and the shear visocity is not small in contrast to the suggestion by\nthe experiment.",
        "positive": "Machine learning enables polymer cloud-point engineering via inverse\n  design: Inverse design is an outstanding challenge in disordered systems with\nmultiple length scales such as polymers, particularly when designing polymers\nwith desired phase behavior. We demonstrate high-accuracy tuning of\npoly(2-oxazoline) cloud point via machine learning. With a design space of four\nrepeating units and a range of molecular masses, we achieve an accuracy of 4\n{\\deg}C root mean squared error (RMSE) in a temperature range of 24-90 {\\deg}C,\nemploying gradient boosting with decision trees. The RMSE is >3x better than\nlinear and polynomial regression. We perform inverse design via particle-swarm\noptimization, predicting and synthesizing 17 polymers with constrained design\nat 4 target cloud points from 37 to 80 {\\deg}C. Our approach challenges the\nstatus quo in polymer design with a machine learning algorithm, that is capable\nof fast and systematic discovery of new polymers."
    },
    {
        "anchor": "Loops are Geometric Catalysts for DNA Integration: The insertion of HIV and other DNA elements within genomes underpins both\ngenetic diversity and disease when unregulated. Most of these insertions are\nnot random and occupy specific positions within the genome but the physical\nmechanisms underlying the integration site selection are poorly understood.\nHere we perform Molecular Dynamics simulations to study the insertion of DNA\nelements, such as HIV viral DNA or transposons, into naked DNA or chromatin\nsubstrate. More specifically, we explore the role of loops in the DNA substrate\nand discover that they act as \"geometric catalysts\" for DNA integration.\nAdditionally, we discover that the 1D and 3D clustering of loops affects the\ndistribution of integration sites. Finally, we show that loops may compete with\nnucleosomes at attracting DNA integrations. These results may be tested in\nvitro and they may help to understand patterns of DNA insertions with\nimplications in genome evolution and gene therapy.",
        "positive": "Coarse-graining microscopic strains in a harmonic, two-dimensional solid\n  and its implications for elasticity: non-local susceptibilities and\n  non-affine noise: In soft matter systems the local displacement field can be accessed directly\nby video microscopy enabling one to compute local strain fields and hence the\nelastic moduli using a coarse-graining procedure. We study this process for a\nsimple triangular lattice of particles connected by harmonic springs in\ntwo-dimensions. Coarse-graining local strains obtained from particle\nconfigurations in a Monte Carlo simulation generates non-trivial, non-local\nstrain correlations (susceptibilities), which may be understood within a\ngeneralized, Landau type elastic Hamiltonian containing up to quartic terms in\nstrain gradients (K. Franzrahe et al., Phys. Rev. E 78, 026106 (2008)). In\norder to demonstrate the versatility of the analysis of these correlations and\nto make our calculations directly relevant for experiments on colloidal solids,\nwe systematically study various parameters such as the choice of statistical\nensemble, presence of external pressure and boundary conditions. We show that\nspecial care needs to be taken for an accurate application of our results to\nactual experiments, where the analyzed area is embedded within a larger system,\nto which it is mechanically coupled. Apart from the smooth, affine strain\nfields, the coarse-graining procedure also gives rise to a noise field made up\nof non-affine displacements. Several properties of this noise field may be\nrationalized for the harmonic solid using a simple \"cell model\" calculation.\nFurthermore the scaling behavior of the probability distribution of the noise\nfield is studied and a master curve is obtained."
    },
    {
        "anchor": "Numerical Modeling of Complex Porous Media For Borehole Applications: The diffusion/relaxation behavior of polarized spins of pore filling fluid,\nas often probed by NMR relaxometry, is widely used to extract information on\nthe pore-geometry. Such information is further interpreted as an indicator of\nthe key transport property of the formation in the oil industry. As the\nimportance of reservoirs with complex pore geometry grows, so does the need for\ndeeper understanding of how these properties are inter-related. Numerical\nmodeling of relevant physical processes using a known pore geometry promises to\nbe an effective tool in such endeavor. Using a suite of numerical techniques\nbased on random-walk (RW) and Lattice-Boltzmann (LB) algorithms, we compare\nsandstone and carbonate pore geometries in their impact on NMR and flow\nproperties. For NMR relaxometry, both laboratory measurement and simulation\nwere done on the same source to address some of the long-standing issues in its\nborehole applications. Through a series of \"numerical experiments\" in which the\ninterfacial relaxation properties of the pore matrix is varied systematically,\nwe study the effect of a variable surface relaxivity while fully incorporating\nthe complexity of the pore geometry. From combined RW and LB simulations, we\nalso obtain diffusion-convection propagator and compare the result with\nexperimental and network-simulation counterparts.",
        "positive": "A statistical mechanics framework for static granular matter: The physical properties of granular materials have been extensively studied\nin recent years. So far, however, there exists no theoretical framework which\ncan explain the observations in a unified manner beyond the phenomenological\njamming diagram [1]. This work focuses on the case of static granular matter,\nwhere we have constructed a statistical ensemble [2] which mirrors equilibrium\nstatistical mechanics. This ensemble, which is based on the conservation\nproperties of the stress tensor, is distinct from the original Edwards ensemble\nand applies to packings of deformable grains. We combine it with a field\ntheoretical analysis of the packings, where the field is the Airy stress\nfunction derived from the force and torque balance conditions. In this\nframework, Point J characterized by a diverging stiffness of the pressure\nfluctuations. Separately, we present a phenomenological mean-field theory of\nthe jamming transition, which incorporates the mean contact number as a\nvariable. We link both approaches in the context of the marginal rigidity\npicture proposed by [3, 4]."
    },
    {
        "anchor": "Correlation functions in mixtures with energetically favoured\n  nearest-neighbours of different kind: a size-asymmetric case: Binary mixtures of hard-spheres with different diameters and square-well\nattraction between different particles are studied by theory and Monte Carlo\nsimulations. In our mesoscopic theory, local fluctuations of the volume\nfraction of the two components are taken into account. Semi-quantitative\nagreement between the simulation and theoretical results is obtained, except\nfrom very small distances. The correlation functions exhibit exponentially\ndamped oscillations, with the period determined by the interaction potential,\nand both the amplitude and the correlation length increasing significantly with\nincreasing diameter ratio. Increasing size asymmetry leads also to decreasing\nfluctuations of the number of the smaller particles in the attractive shell of\nthe bigger ones. For small size asymmetry, the strongest correlations occur for\ncomparable volume fraction of the two components. When the size ratio\nincreases, the maximum of the structure factor moves to a larger volume\nfraction of the bigger particles, and for the size ratio as large as 4, the\nmaximum goes beyond the accessible range of volume fractions. Our results show\nthat when the neighbourhood of different particles is energetically favoured,\nthe particles are much more uniformly distributed than in the random\ndistribution even at relatively high temperature, especially for large size\nasymmetry.",
        "positive": "Models of granular ratchets: We study a general model of granular Brownian ratchet consisting of an\nasymmetric object moving on a line and surrounded by a two-dimensional granular\ngas, which in turn is coupled to an external random driving force. We discuss\nthe two resulting Boltzmann equations describing the gas and the object in the\ndilute limit and obtain a closed system for the first few moments of the system\nvelocity distributions. Predictions for the net ratchet drift, the variance of\nits velocity fluctuations and the transition rates in the Markovian limit, are\ncompared to numerical simulations and a fair agreement is observed."
    },
    {
        "anchor": "A coarse grained model of polymer networks focusing on the intermediate\n  length scales: We propose a coarse-grained model for polymer chains and polymer networks\nbased on the meso-scale dynamics. The model takes the internal degrees of\nfreedom of the constituent polymer chains into account using memory functions\nand colored noises. We apply our model to dilute polymer solutions and polymer\nnetworks. A numerical simulation on a dilute polymer solution demonstrates the\nvalidity of the assumptions on the dynamics of our model. By applying this\nmodel to polymer networks, we find a transition in the dynamical behavior from\nan isolated chain state to a network state.",
        "positive": "Pulling a folded polymer through a nanopore: We investigate the translocation dynamics of a folded linear polymer which is\npulled through a nanopore by an external force. To this end, we generalize the\niso-flux tension propagation (IFTP) theory for end-pulled polymer translocation\nto include the case of two segments of the folded polymer traversing\nsimultaneously trough the pore. Our theory is extensively benchmarked with\ncorresponding Molecular Dynamics (MD) simulations. The translocation process\nfor a folded polymer can be divided into two main stages. In the first stage,\nboth branches are traversing the pore and their dynamics is coupled. If the\nbranches are not of equal length, there is a second stage where translocation\nof the shorter branch has been completed. Using the assumption of equal monomer\nflux of both branches, we analytically derive the equations of motion for both\nbranches and characterise the translocation dynamics in detail from the average\nwaiting time and its scaling form. Moreover, MD simulations are used to study\nadditional details of translocation dynamics such as the translocation time\ndistribution and individual monomer velocities."
    },
    {
        "anchor": "Shear dynamics of confined membranes: We model the nonlinear response of a lubricated contact composed of a\ntwo-dimensional lipid membrane immersed in a simple fluid between two parallel\nflat and porous walls under shear. The nonlinear dynamics of the membrane gives\nrise to a rich dynamical behavior depending on the shear velocity. In quiescent\nconditions (i.e., absence of shear), the membrane freezes into a disordered\nlabyrinthine wrinkle pattern. In the presence of shear, we find four different\nregimes depending on the shear rate. Regime I. For small shear, the\nlabyrinthine pattern is still frozen, but exhibits a small drift which is\nmainly along the shear direction. In this regime, the tangential forces on the\nwalls due to the presence of the membrane increase linearly with the shear\nrate. Regime II. When the shear rate is increased above a critical value, the\nmembrane rearranges, and wrinkles start to align along the shear direction.\nThis regime is accompanied by a sharp drop of the tangential forces on the\nwall. Regime III. For larger shear rates, the wrinkles align strongly along the\nshear direction, with a set of dislocation defects which assemble in pairs. The\ntangential forces are then controlled by the number of dislocations, and by the\nnumber of wrinkles between the two dislocations within each dislocation pairs.\nIn this dislocation-dominated regime, the tangential forces in the transverse\ndirection most often exceed those in the shear direction. Regime IV. For even\nlarger shear, the membrane organizes into a perfect array of parallel stripes\nwith no defects. The wavelength of the wrinkles is still identical to the\nwavelength in the absence of shear. In this final regime, the tangential forces\ndue to the membrane vanish. These behaviors give rise to a non-linear\nrheological behavior of lubricated contacts containing membranes.",
        "positive": "Dynamics of active membranes with internal noise: We study the time-dependent height fluctuations of an active membrane\ncontaining energy-dissipating pumps that drive the membrane out of equilibrium.\nUnlike previous investigations based on models that neglect either curvature\ncouplings or random fluctuations in pump activities, our formulation explores\ntwo new models that take both of these effects into account. In the first\nmodel, the magnitude of the nonequilibrium forces generated by the pumps is\nallowed to fluctuate temporally. In the second model, the pumps are allowed to\nswitch between \"on\" and \"off\" states. We compute the mean squared displacement\nof a membrane point for both models, and show that they exhibit distinct\ndynamical behaviors from previous models, and in particular, a superdiffusive\nregime specifically arising from the shot noise."
    },
    {
        "anchor": "Transport of a self-propelled tracer through a hairy cylindrical\n  channel: interplay of stickiness and activity: Active transport of biomolecules assisted by motor proteins is imperative for\nthe proper functioning of cellular activities. Inspired by the diffusion of\nactive agents in crowded cellular channels, we computationally investigate the\ntransport of an active tracer through a polymer grafted cylindrical channel by\nvarying the activity of the tracer and stickiness of the tracer to the\npolymers. Our results reveal that the passive tracer exhibits profound\nsubdiffusion with increasing stickiness by exploring deep into the grafted\npolymeric zone, while purely repulsive one prefers to diffuse through the\npore-like space created along the cylindrical axis of the channel. In contrast,\nthe active tracer shows faster dynamics and intermediate superdiffusion even\nthough the tracer preferentially stays close to the dense polymeric region.\nThis observation is further supported by the sharp peaks in the density profile\nof the probability of radial displacement of the tracer. We discover that the\nactivity plays an important role in deciding the pathway that the tracer takes\nthrough the narrow channel. Interestingly, increasing the activity washes out\nthe effect of stickiness. Adding to this, van-Hove functions manifest that the\nactive tracer dynamics deviates from Gaussianity, and the degree of deviation\ngrows with the activity. Our work has direct implications on how effective\ntransportation and delivery of cargo can be achieved through a confined medium\nwhere activity, interactions, and crowding are interplaying. Looking ahead,\nthese factors will be crucial for understanding the mechanism of artificial\nself-powered machines navigating through the cellular channels and performing\nin vivo challenging tasks.",
        "positive": "Ferrofluid aggregates phase transitions in the planar magnetic field: The influence of the cyclic heating and cooling on properties of the\naggregates (aka \"ferrofluid clusters\") in a ferrofluid, which made on the basis\nof magnetite nanoparticles, are investigated. The heating of the ferrofluid\nlayer with such aggregates leads to equalization of the concentration between\nhigh- and low-concentrated phases. The temperature of the equalization of the\nphase concentrations was determined at different values of an external constant\nmagnetic field, which was applied parallel to the layer of the ferrofluid. The\ntemperature of the destruction of a periodic structure of the magnetic\naggregates, which were formed during cooling of a homogeneous phase of the\nferrofluid, was obtained at the different values of the applied external\nmagnetic field."
    },
    {
        "anchor": "Dynamics in a supercooled molecular liquid: Theory and Simulations: We report extensive simulations of liquid supercooled states for a simple\nthree-sites molecular model, introduced by Lewis and Wahnstr\"om [L. J. Lewis\nand G. Wahnstr\"om, Phys. Rev. E 50, 3865 (1994)] to mimic the behavior of\northo-terphenyl. The large system size and the long simulation length allow to\ncalculate very precisely --- in a large q-vector range --- self and collective\ncorrelation functions, providing a clean and simple reference model for\ntheoretical descriptions of molecular liquids in supercooled states. The time\nand wavevector dependence of the site-site correlation functions are compared\nwith detailed predictions based on ideal mode-coupling theory, neglecting the\nmolecular constraints. Except for the wavevector region where the dynamics is\ncontrolled by the center of mass (around 9 nm-1), the theoretical predictions\ncompare very well with the simulation data. ~",
        "positive": "Emergent self-propulsion at low Reynolds number: We here demonstrate the experimental realization of inanimate micro-swimmer\ncomplexes showing emergent self-propulsion at low Reynolds number Re < 10^(-4)\nin quasi 2D colloidal systems. Guided by the substrate, self-organized\npropulsion occurs for up to 25min with typical velocities of 1-3 \\mu m/s, while\nnone of the involved constituents shows self-propulsion on its own."
    },
    {
        "anchor": "Simulation of a cusped bubble rising in a viscoelastic fluid with a new\n  numerical method: We developed a new lattice Boltzmann method that allows the simulation of\ntwo-phase flow of viscoelastic liquid mixtures. We used this new method to\nsimulate a bubble rising in a viscoelastic fluid and were able to reproduce the\nexperimentally observed cusp at the trailing end of the bubble.",
        "positive": "Effect of liquid state organization on microstructure and strength of\n  model multicomponent solids: When a multicomponent liquid composed of particles with random interactions\nis slowly cooled below the freezing temperature, the fluid reorganises in order\nto increase (decrease) the number of strong (weak) attractive interactions and\nsolidifies into a microphase-separated structure composed of domains of\nstrongly and of weakly interacting particles. Using Langevin dynamics\nsimulations of a model system we find that the limiting tensile strength of\nsuch solids can exceed that of one-component solids."
    },
    {
        "anchor": "Quantitative analysis of the debonding structure of soft adhesives: We experimentally investigate the growth dynamics of cavities nucleating\nduring the first stages of debonding of three different model adhesives. The\nmaterial properties of these adhesives range from a more liquid-like material\nto a soft viscoelastic solid and are carefully characterized by small strain\noscillatory shear rheology as well as large strain uniaxial extension. The\ndebonding experiments are performed on a probe tack set-up. Using high contrast\nimages of the debonding process and precise image analysis tools we quantify\nthe total projected area of the cavities, the average cavity shape and growth\nrate and link these observations to the material properties. These measurements\nare then used to access corrected effective stress and strain curves that can\nbe directly compared to the results from the uniaxial extension.",
        "positive": "Pinch-off of viscoelastic particulate suspensions: The formation of drops of a complex fluid, for instance including dissolved\npolymers and/or solid particles, has practical implications in several\nindustrial and biophysical processes. In this Letter, we experimentally\ninvestigate the generation of drops of a viscoelastic suspension, made of\nnon-Brownian spherical particles dispersed in a dilute polymer solution. Using\nhigh-speed imaging, we characterize the different stages of the detachment. Our\nexperiments show that the particles primarily affect the initial Newtonian\nnecking by increasing the fluid viscosity. In the viscoelastic regime,\nparticles do not affect the thinning until the onset of the blistering\ninstability, which they accelerate. We find that the transition from one regime\nto another, which corresponds to the coil-stretch transition of the polymer\nchains, strongly depends on the particle content. Considering that the presence\nof rigid particles increase the deformation of the liquid phase, we propose an\nexpression for the local strain rate in the suspension, which rationalizes our\nexperimental results. This method could enable the precise measurement of local\nstresses in particulate suspensions."
    },
    {
        "anchor": "Nanoscale simulations of directional locking: When particles suspended in a fluid are driven through a regular lattice of\ncylindrical obstacles, the particle motion is usually not simply in the\ndirection of the force, and in the high Peclet number limit particle\ntrajectories tend to lock along certain lattice directions. By means of\nmolecular dynamics simulations we show that this effect persists in the\npresence of molecular diffusion for nanoparticle flows, provided the Peclet\nnumber is not too small. We examine the effects of varying particle and\nobstacle size, the method of forcing, solid roughness, and particle\nconcentration. While we observe trajectory locking in all cases, the degree of\nlocking varies with particle size and these flows may have application as a\nseparation technique.",
        "positive": "Geometric evolution as a source of discontinuous behavior in soft\n  condensed matter: Geometric evolution represents a fundamental aspect of many physical\nphenomena. In this paper we consider the geometric evolution of structures that\nundergo topological changes. Topological changes occur when the shape of an\nobject evolves such that it either breaks apart or converges back into itself\nto form a loop. Changes to the topology of an object are fundamentally discrete\nevents. We consider how discontinuities arise during geometric evolution\nprocesses by characterizing the possible topological events and analyzing the\nassociated source terms based on evolution equations for geometric invariants.\nWe show that the discrete nature of a topological change leads to discontinuous\nsource terms that propagate to physical variables."
    },
    {
        "anchor": "Intracellular micro-rheology probed by micron-sized wires: In the last decade, rapid advances have been made in the field of\nmicro-rheology of cells and tissues. Given the complexity of living systems,\nthere is a need for the development of new types of nano- and micron-sized\nprobes, and in particular of probes with controlled interactions with the\nsurrounding medium. In the present paper, we evaluate the use of micron-sized\nwires as potential probes of the mechanical properties of cells. The wire-based\nmicro-rheology technique is applied to living cells such as murine fibroblasts\nand canine kidney epithelial cells. The mean-squared angular displacement\n(MSAD) of wires associated to their rotational dynamics is obtained as a\nfunction of the time using optical microscopy and image processing. It reveals\na Brownian-like diffusive regime where the MSA scale linearly with time and as\nthe inverse of the cube of the wire length. This scaling suggests that an\neffective viscosity of the intracellular medium can be determined, and that in\nthe range 1 - 10 micrometers it does not depend on the length scale over which\nit is measured.",
        "positive": "A statistical mechanical model for drug release: relations between\n  release parameters and porosity: A lattice gas model is proposed for investigating the release of drug\nmolecules on devices with semi-permeable, porous membranes in two and three\ndimensions. The kinetic of this model was obtained through the analytical\nsolution of the three-dimension diffusion equation for systems without membrane\nand with Monte Carlo simulations. Pharmaceutical data from drug release is\nusually adjusted to the Weibull function, $\\exp [-(t/\\tau)^b ]$, also known as\nstretched exponential, and the dependence of adjusted parameters $b$ and $\\tau$\nis usually associated, in the pharmaceutical literature, with physical\nmechanisms dominating the drug dynamics inside the capsule. The relation of\nparameters $\\tau$ and $b$ with porosity $\\lambda$ are found to satisfy, a\nsimple linear relation for between $\\tau$ and $\\lambda^{-1}$, which can be\nexplained through simple physically based arguments, and a scaling relation\nbetween $b$ and $\\lambda$, with the scaling coefficient proportional to the\nsystem dimension."
    },
    {
        "anchor": "On the insights into phases of liquid water from study of its unusual\n  glass-forming properties: We investigate whether an interpretation of water's thermodynamics [Science,\n319, 582 (2008)] by using analogy with the binary metal alloys lambda-type\nordering transition or buckminsterfullerene's orientational-ordering transition\nhas merit. On examining the heat capacity data used for the nanoconfined water,\nthe construction of the heat capacity peak, and the number of water molecules\nin nanoconfinement, we find that (i) the peak had been obtained by joining the\ndata for emulsified water with that of the nanoconfined water and (ii) only\nthree water molecules can be fitted across the 1.1 nm diameter pores used in\nthe study, two of which form a cylindrical shell that is hydrogen bonded to\nsilica. The remaining connectedness of one water molecule would not produce a\nmetal alloy-like lambda-transition, or cooperative motions. Therefore, there is\nno basis for considering such an ordering in supercooled water.",
        "positive": "Hyperforce balance via thermal Noether invariance of any observable: Noether invariance in statistical mechanics provides fundamental connections\nbetween the symmetries of a physical system and its conservation laws and sum\nrules. The latter are exact identities that involve statistically averaged\nforces and force correlations and they are derived from statistical mechanical\nfunctionals. However, the implications for more general observables and order\nparameters are unclear. Here, we demonstrate that thermally averaged classical\nphase space functions are associated with exact hyperforce sum rules that\nfollow from translational Noether invariance. Both global and locally resolved\nidentities hold and they relate the mean gradient of a phase-space function to\nits negative mean product with the total force. Similar to Hirschfelder's\nhypervirial theorem, the hyperforce sum rules apply to arbitrary observables in\nequilibrium. Exact hierarchies of higher-order sum rules follow iteratively. As\napplications we investigate via computer simulations the emerging one-body\nforce fluctuation profiles in confined liquids. These local correlators\nquantify spatially inhomogeneous self-organization and their measurement allows\nfor the development of stringent convergence tests and enhanced sampling\nschemes in complex systems."
    },
    {
        "anchor": "Critical behaviour of ionic fluids: Recently we proposed a microscopic approach to the description of the phase\nbehaviour and critical phenomena in binary fluid mixtures. It was based on the\nmethod of collective variables (CV) with a reference system. The approach\nallowed us to obtain the functional of the Ginzburg-Landau-Wilson (GLW)\nHamiltonian expressed in terms of the CV (fluctuating densities). The\ncorresponding set of CV included the variable connected with the order\nparameter. In this paper we use this approach to the study of the critical\nbehaviour of ionic fluids. For the restricted primitive model (RPM) we obtain\nthe functional of the grand partition function in the phase space of the two\nfluctuating fields conjugate to the fluctuating densities. First we calculate\nthe phase diagram of the RPM in the mean-field (MF) approximation and then we\ndo this calculation taking into account the terms of the higher orders in the\neffective Hamiltonian. In the both cases the phase diagrams demonstrate the\ngas-liquid (GL) and charge ordering phase instabilities. In the latter case,\nthe obtained value for the GL critical temperature is in good agreement with\nthe MC simulation data whereas the critical density is underestimated. The\nexplicit expression found for the grand thermodynamic potential in the vicinity\nof the GL critical point implies a classical critical behaviour of the RPM.",
        "positive": "Nonlinear elasticity of incompatible surface growth: Surface growth is a crucial component of many natural and artificial\nprocesses from cell proliferation to additive manufacturing. In elastic systems\nsurface growth is usually accompanied by the development of geometrical\nincompatibility leading to residual stresses and triggering various\ninstabilities. In a recent paper (PRL, 119, 048001, 2017) we developed a\nlinearized elasticity theory of incompatible surface growth which\nquantitatively linked deposition protocols with post-growth states of stress.\nHere we extend this analysis to account for both physical and geometrical\nnonlinearities of an elastic solid. The new development reveals the\nshortcomings of the linearized theory, in particular, its inability to describe\nkinematically confined surface growth and to account for growth-induced elastic\ninstabilities."
    },
    {
        "anchor": "Multi-scale modeling of poly(isoprene) melts: Atomistic (atom-scale) and coarse-grained (meso-scale) simulations of\nstructure and dynamics of poly-isoprene melts are compared. The local structure\nand chain packing is mainly determined by the atomistic details of the polymer\narchitecture. The large-time dynamics encountered in NMR experiments can be\nexplained by meso-scale simulations including stiffness. The connecting link\nbetween the two scales is the stiffness which, although being a local property,\ninfluences strongly even the long-timescale dynamics. The standard reptation\nscenario fails to explain the observed dynamics. We propose strong reptation as\na modified reptation scenario in which the local Rouse motion is absent.",
        "positive": "Free volume under shear: Using an athermal quasistatic simulation protocol, we study the distribution\nof free volumes in sheared hard-particle packings close to, but below, the\nrandom-close packing threshold. We show that under shear, and independent of\nvolume fraction, the free volumes develop features similar to close-packed\nsystems -- particles self-organize in a manner as to mimick the isotropically\njammed state. We compare athermally sheared packings with thermalized packings\nand show that thermalization leads to an erasure of these structural features.\nThe temporal evolution, in particular the opening-up and the closing of\nfree-volume patches is associated with the single-particle dynamics, showing a\ncrossover from ballistic to diffusive behavior."
    },
    {
        "anchor": "Crossover from Intermittent to Continuum Dynamics for Locally Driven\n  Colloids: We simulate a colloid with charge q_d driven through a disordered assembly of\ninteracting colloids with charge q and show that, for q_d \\approx q, the\nvelocity-force relation is nonlinear and the velocity fluctuations of the\ndriven particle are highly intermittent with a 1/f characteristic. When q_d >>\nq, the average velocity ddrops, the velocity force relation becomes linear, and\nthe velocity fluctuations are Gaussian. We discuss the results in terms of a\ncrossover from strongly intermittent heterogeneous dynamics to continuum\ndynamics. We also make several predictions for the transient response in the\ndifferent regimes.",
        "positive": "Lattice Boltzmann model for combustion and detonation: In this paper we present a lattice Boltzmann model for combustion and\ndetonation. In this model the fluid behavior is described by a\nfinite-difference lattice Boltzmann model by Gan et al. [Physica A, 2008, 387:\n1721]. The chemical reaction is described by the Lee-Tarver model [Phys.\nFluids, 1980, 23: 2362]. The reaction heat is naturally coupled with the flow\nbehavior. Due to the separation of time scales in the chemical and\nthermodynamic processes, a key technique for a successful simulation is to use\nthe operator-splitting scheme. The new model is verified and validated by\nwell-known benchmark tests. As a specific application of the new model, we\nstudied the simple steady detonation phenomenon. To show the merit of LB model\nover the traditional ones, we focus on the reaction zone to study the\nnon-equilibrium effects. It is interesting to find that, at the von Neumann\npeak, the system is nearly in its thermodynamic equilibrium. At the two sides\nof the von Neumann peak, the system deviates from its equilibrium in opposite\ndirections. In the front of von Neumann peak, due to the strong compression\nfrom the reaction product behind the von Neumann peak, the system experiences a\nsudden deviation from thermodynamic equilibrium. Behind the von Neumann peak,\nthe release of chemical energy results in thermal expansion of the matter\nwithin the reaction zone, which drives the system to deviate the thermodynamic\nequilibrium in the opposite direction. From the deviation from thermodynamic\nequilibrium, defined in this paper, one can understand more on the macroscopic\neffects of the system due to the deviation from its thermodynamic equilibrium."
    },
    {
        "anchor": "General Synthetic Route Towards Highly Dispersed Metal Clusters Enabled\n  by Poly(ionic liquid)s: The capability to synthesize a broad spectrum of metal clusters (MCs) with\ntheir size controllable in a subnanometer scale presents an enticing prospect\nfor exploring nanosize-dependent properties. Here we report an innovative\ndesign of a capping agent from a polytriazolium poly(ionic liquid) (PIL) in a\nvesicular form in solution that allows for crafting a variety of MCs including\ntransition metals, noble metals, and their bimetallic alloy with precisely\ncontrolled sizes (~ 1 nm) and record-high catalytic performance. The\nultrastrong stabilization power is result of an unusual synergy between the\nconventional binding sites in the heterocyclic cations in PIL, and an in-situ\ngenerated polycarbene structure induced simultaneously to the reduction\nreaction. INTRODUCTION",
        "positive": "Pathways, Scaling Laws and Analytical Solutions for Crease Formations in\n  a Gel Layer: An analytical study on crease formations in a swelling gel layer is\nconducted. By exploring the smallness of the layer thickness and using a method\nof coupled series-asymptotic expansions, the original nonlinear eigenvalue\nproblem of partial differential equations is reduced to one of ordinary\ndifferential equations. The latter problem is then solved analytically to\nobtain closed-form solutions for all the post-bifurcation branches. With the\navailable analytical results, a number of deep insights on crease formations\nare provided, including the unveiling of three pathways to crease (depending on\nthe layer thickness), determination of the bifurcation type, establishment of a\nlower bound for mode numbers and two scaling laws. Also, a number of\nexperimental results are captured, which are then nicely interpreted based on\nthe analytical solutions. In particular, it is shown that some critical\nphysical quantities are invariant with respect to the thickness at the moment\nof crease formation. It appears that the present work offers a comprehensive\nunderstanding on crease formation, a widely-spread phenomenon."
    },
    {
        "anchor": "Topological balance of cell distributions in plane monolayers: Most of normal proliferative epithelia of plants and metazoans are\ntopologically invariant and characterized by similar cell distributions\naccording to the number of cell neighbors (DCNs). Here we study peculiarities\nof these distributions and explain why the DCN obtained from the location of\nintercellular boundaries and that based on the Voronoi tessellation with nodes\nlocated on cell nuclei may differ from each other. As we demonstrate, special\nmicrodomains where four or more intercellular boundaries converge are\ntopologically charged. Using this fact, we deduce a new equation describing the\ntopological balance of the DCNs. The developed theory is applied for a series\nof microphotographs of non-tumoral epithelial cells of the human cervix\n(HCerEpiC) to improve the image processing near the edges of microphotographs\nand reveal the topological invariance of the examined monolayers. Special\ncontact microdomains may be present in epithelia of various natures, however,\nconsidering the well-known vertex model of epithelium, we show that such\ncontacts are absent in the usual solid-like state of the model and appear only\nin the liquid-like cancer state. Also, we discuss a possible biological role of\nspecial contacts in context of proliferative epithelium dynamics and tissue\nmorphogenesis.",
        "positive": "Confined granular gases under the influence of vibrating walls: The dynamics of a system composed of inelastic hard spheres or disks that are\nconfined between two parallel vertically vibrating walls is studied (the\nvertical direction is defined as the direction perpendicular to the walls). The\ndistance between the two walls is supposed to be larger than twice the diameter\nof the particles so that the particles can pass over each other, but still much\nsmaller than the dimensions of the walls. Hence, the system can be considered\nto be quasi-two-dimensional (quasi-one-dimensional) in the hard spheres (disks)\ncase. For dilute systems, a closed evolution equation for the one-particle\ndistribution function is formulated that takes into account the effects of the\nconfinement. Assuming the system is spatially homogeneous, the kinetic equation\nis solved approximating the distribution function by a two-temperatures\n(horizontal and vertical) gaussian distribution. The obtained evolution\nequations for the partial temperatures are solved, finding a very good\nagreement with Molecular Dynamics simulation results for a wide range of the\nparameters (inelasticity, height and density) for states whose projection over\na plane parallel to the walls is homogeneous. In the stationary state, where\nthe energy lost in collisions is compensated by the energy injected by the\nwalls, the pressure tensor in the horizontal direction is analyzed and its\nrelation with an instability of the homogenous state observed in the\nsimulations is discussed."
    },
    {
        "anchor": "Comparison of 2D melting criteria in a colloidal system: We use super-paramagnetic spherical particles which are arranged in a\ntwo-dimensional monolayer at a water/air interface to investigate the crystal\nto liquid phase transition. According to the KTHNY theory a crystal melts in\nthermal equilibrium by two continuous phase transitions into the isotropic\nliquid state with an intermediate phase, commonly known as hexatic phase. We\nverify the significance of several criteria based on dynamical and structural\nproperties to identify the crystal - hexatic and hexatic - isotropic liquid\nphase transition for the same experimental data of the given setup. Those\ncriteria are the bond orientational correlation function, the Larson-Grier\ncriterion, 2D dynamic Lindemann parameter, the bond-orientational\nsusceptibility, the 2D Hansen-Verlet rule, the L\\\"{o}wen-Palberg-Simon\ncriterion as well as a criterion based on the shape factor of Voronoi cells and\nMinkowski functionals. For our system with long range repulsion, the bond order\ncorrelation function and bond order susceptibility works best to identify the\nhexatic - isotropic liquid transition and the 2D dynamic Lindemann parameter\nidentifies unambiguously the hexatic - crystalline transition.",
        "positive": "Dielectric relaxation of water below the melting point: the effect of\n  inner pressure: Despite water is the most studied substance in the Earth, it is not\ncompletely understood why its structural and dynamical properties give rise to\nsome anomalous behaviors. Interesting properties emerge when experiments at low\ntemperatures and/or high pressures, are performed. Here we report dielectric\nmeasurements of cold water under constrained conditions, i.e. water that below\nthe melting point can not freeze. The inner pressure shifts the {\\alpha}\nrelaxation peak to similar frequencies as seen in ice Ih. Also, when we reach\nthe triple point at 251 K, ice III seems to form. As far as we know, this via\nto obtain such crystalline phase has not been observed."
    },
    {
        "anchor": "Dynamics of Droplets Moving on Lubricated Polymer Brushes: Understanding the dynamics of drops on polymer-coated surfaces is crucial for\noptimizing applications such as self-cleaning materials or microfluidic\ndevices. While the static and dynamic properties of deposited drops have been\nwell characterised, a microscopic understanding of the underlying dynamics is\nmissing. In particular, it is unclear how drop dynamics depends on the amount\nof uncrosslinked chains in the brush, because experimental techniques fail to\nquantify those. Here we use coarse-grained simulations to study droplets moving\non a lubricated polymer brush substrate under the influence of an external body\nforce. The simulation model is based on the many body dissipative particle\ndynamics (mDPD) method and designed to mimic a system of water droplets on\npolydimethylsiloxane (PDMS) brushes with chemically identical PDMS lubricant.\nIn agreement with experiments, we find a sublinear power law dependence between\nthe external force $F$ and the droplet velocity $v$, $F \\propto v^\\alpha$ with\n$\\alpha <1$; however, the exponents differ ($\\alpha \\sim 0.6-0.7$ in\nsimulations versus $\\alpha \\sim 0.25$ in experiments). With increasing\nvelocity, the droplets elongate and the receding contact angle decreases,\nwhereas the advancing contact angle remains roughly constant. Analyzing the\nflow profiles inside the droplet reveals that the droplets do not slide, but\nroll, with vanishing slip at the substrate surface. Surprisingly, adding\nlubricant has very little effect on the effective friction force between the\ndroplet and the substrate, even though it has a pronounced effect on the size\nand structure of the wetting ridge, especially above the cloaking transition.",
        "positive": "Realizing negative Poisson's ratio in unstressed spring networks: When randomly displacing the nodes of a crystalline and unstressed spring\nnetwork, we find that the Possion's ratio decreases with the increase of\nstructural disorder and even becomes negative. Employing our finding that\nlonger springs tend to contribute more to the shear modulus but less to the\nbulk modulus, we are able to achieve negative Poisson's ratio with lower\nstructural disorder by attributing each spring a length dependent stiffness.\nEven with perfect crystalline structure, the network can have negative\nPossion's ratio, if the stiffness of each spring is set by its virtual length\nafter a virtual network distortion. We also reveal that the nonaffine\ncontribution arising from the structural or spring constant disorder produced\nin some cooperative way by network distortion is essential to the emergence of\nnegative Poisson's ratio."
    },
    {
        "anchor": "Kinetics of Spinodal Phase Separation in Unstable Thin Liquid Films: We study universality in the kinetics of spinodal phase separation in\nunstable thin liquid films, via simulations of the thin film equation. It is\nshown that in addition to morphology and free energy,the number density of\nlocal maxima in the film profile can also be used to identify the early,\nintermediate and late stages of spinodal phase separation. A universal curve\nbetween the number density of local maxima and rescaled time describes the\nkinetics of early stage in d = 2, 3. The Lifshitz-Slyozov exponent of -1/3\ndescribes the kinetics of the late stage in d = 2 even in the absence of\ncoexisting equilibrium phases.",
        "positive": "Collective dynamics in two-dimensional aggregations with competing\n  interactions: A generic aggregate forming system in two dimensions (2D) is studied using\ncanonical ensemble constant temperature molecular dynamics simulation. The\naggregates form due to the competition between short range attraction and long\nrange repulsion of pair-wise interactions. Choosing the appropriate set of\ninteraction parameters, we focus on characterising the collective dynamics in\ntwo specific morphologies, {\\it viz.} compact and string-like aggregates. We\nfocus on the temporal evolution of the mobility of an individual particle and\nthe dynamic change in its nearest neighbourhood, measured in terms of the\nDebye-Waller factor ($\\bar{u}_i^2$) and the non-affine parameter ($\\chi$),\nrespectively (defined in the text), and their interrelation over several\nlengths of observation time $\\tau_w$. The distribution for both measures are\nfound to follow the relation: $P(x;\\tau_w) \\sim \\tau_w^{-\\gamma}x$ for the\nmeasured quantity $x$. The exponent $\\gamma$ is equal to $2$ and $1$\nrespectively, for the compact and string-like morphologies following the ideal\nfractal dimension of these aggregates. A functional dependence between these\ntwo observables is determined from a detailed statistical analysis of their\njoint and conditional distributions. The results obtained can readily be used\nand verified by experiments on aggregate forming systems such as globular\nproteins, nanoparticle self-assembly etc. Further, the insights gained from\nthis study might be useful to understand the evolution of collective dynamics\nin diverse glass-forming systems."
    },
    {
        "anchor": "Detachment of adhesive normal contact between a rigid circular flat\n  punch and a viscoelastic half-space: We propose an approach to describe the propagation of a crack (or boundary of\nan adhesive contact) in a viscoelastic material which is only based on the\nconsideration of the rheology of the material without the introduction of any\nadditional dependency of the separation energy on the velocity of crack\npropagation. The suggested idea is illustrated with an example of kinetics of\ndetachment of a flat-ended indenter from a viscoelastic medium. It is shown\nthat under the given assumptions the crack propagation is accelerating until\nthe critical configuration is reached and the contact detaches instantaneously.\nThe suggested criterion can be basically applied to arbitrary shapes and\narbitrary loading histories.",
        "positive": "Wrinkle patterns in active viscoelastic thin sheets: We show that a viscoelastic thin sheet driven out of equilibrium by active\nstructural remodelling develops a rich variety of shapes as a result of a\ncompetition between viscous relaxation and activity. In the regime where active\nprocesses are faster than viscoelastic relaxation, wrinkles that are formed due\nto remodelling are unable to relax to a configuration that minimises the\nelastic energy and the sheet is inherently out of equilibrium. We argue that\nthis non-equilibrium regime is of particular interest in biology as it allows\nthe system to access morphologies that are unavailable if restricted to the\nadiabatic evolution between configurations that minimise the elastic energy\nalone. Here, we introduce activity using the formalism of evolving target\nmetric and showcase the diversity of wrinkling morphologies arising from out of\nequilibrium dynamics."
    },
    {
        "anchor": "Shear dynamics of polydisperse double emulsions: We numerically study the dynamics of a polydisperse double emulsion under a\nsymmetric shear flow. We show that both dispersity and shear rate crucially\naffect the behavior of the innermost drops and of the surrounding shell. While\nat low/moderate values of shear rates the inner drops rotate periodically\naround a common center of mass triggered by the fluid vortex formed within the\nemulsion generally regardless of their polydispersity, at higher values such\ndynamics occurs only at increasing polydispersity, since monodisperse drops are\nfound to align along the shear flow and become approximately motionless at late\ntimes. Our simulations also suggest that increasing polydispersity favours\nclose-range contacts among cores and persistent collisions, while hindering\nshape deformations of the external droplet. A quantitative evaluation of these\neffects is also provided.",
        "positive": "The onset of self-assembly: We have formulated a theory of self-assembly based on the notion of local\ngauge invariance at the mesoscale. Local gauge invariance at the mesoscale\ngenerates the required long- range entropic forces responsible for\nself-assembly in binary systems. Our theory was applied to study the onset of\nmesostructure formation above a critical temperature in estane, a diblock\ncopolymer. We used diagrammatic methods to transcend the Gaussian approximation\nand obtain a correlation length zeta ~ (c-c*)^-gamma, where c* is the minimum\nconcentration below which self-assembly is impossible, c is the current\nconcentration, and gamma was found numerically to be close to 2/3. The\nrenormalized diffusion constant vanishes as the c* is approached, indicating\nthe occurrence of critical slowing down, while the correlation function remains\nfinite at the transition point."
    },
    {
        "anchor": "Shape matters: Competing mechanisms of particle shape segregation: It is well-known that granular mixtures that differ in size or shape\nsegregate when sheared. In the past, two mechanisms have been proposed to\ndescribe this effect, and it is unclear if both exist. To settle this question,\nwe consider a bidisperse mixture of spheroids of equal volume in a rotating\ndrum, where the two mechanisms are predicted to act in opposite directions. We\npresent the first evidence that there are two \\emph{distinct} segregation\nmechanisms driven by relative \\emph{over-stress}. Additionally, we showed that\nfor non-spherical particles, these two mechanisms can act in different\ndirections leading to a competition between the effects of the two. As a\nresult, the segregation intensity varies non-monotonically as a function of\n$AR$, and at specific points, the segregation direction changes for both\nprolate and oblate spheroids, explaining the surprising segregation reversal\npreviously reported. Consistent with previous results, we found that the\nkinetic mechanism is dominant for (almost) spherical particles. Furthermore,\nfor moderate aspect ratios, the kinetic mechanism is responsible for the\nspherical particles segregation to the periphery of the drum, and the gravity\nmechanism plays only a minor role. Whereas, at the extreme values of $AR$, the\ngravity mechanism notably increases and overtakes its kinetic counterpart.",
        "positive": "A design principle for actuation of nematic glass sheets: A continuum mechanical framework is developed for determining a) the class of\nstress-free deformed shapes and corresponding director distributions on the\nundeformed configuration of a nematic glass membrane that has a prescribed\nspontaneous stretch field and b) the class of undeformed configurations and\ncorresponding director distributions on it resulting in a stress-free\n\\emph{given} deformed shape of a nematic glass sheet with a prescribed\nspontaneous stretch field. The proposed solution rests on an understanding of\nhow the Lagrangian dyad of a deformation of a membrane maps into the Eulerian\ndyad in three dimensional ambient space. Interesting connections between these\npractical questions of design and the mathematical theory of isometric\nembeddings of manifolds, deformations between two prescribed Riemannian\nmanifolds, and the slip-line theory of plasticity are pointed out."
    },
    {
        "anchor": "The \"True\" Widom Line for a Square-Well System: In the present paper we propose the van der Waals-like model, which allows a\npurely analytical study of fluid properties including the equation of state,\nphase behavior and supercritical fluctuations. We take a square-well system as\nan example and calculate its liquid - gas transition line and supercritical\nfluctuations. Employing this model allows us to calculate not only the\nthermodynamic response functions (isothermal compressibility $\\beta_T$,\nisobaric heat capacity $C_P$, density fluctuations $\\zeta_T$, and thermal\nexpansion coefficient $\\alpha_T$), but also the correlation length in the fluid\n$\\xi$. It is shown that the bunch of extrema widens rapidly upon departure from\nthe critical point. It seems that the Widom line defined in this way cannot be\nconsidered as a real boundary that divides the supercritical region into the\ngaslike and liquidlike regions. As it has been shown recently, the new dynamic\nline on the phase diagram in the supercritical region, namely the Frenkel line,\ncan be used for this purpose.",
        "positive": "The effect of inertia on sheared disordered solids: Critical scaling of\n  avalanches in two and three dimensions: Molecular dynamics simulations with varying damping are used to examine the\neffects of inertia and spatial dimension on sheared disordered solids in the\nathermal, quasistatic limit. In all cases the distribution of avalanche sizes\nfollows a power law over at least three orders of magnitude in dissipated\nenergy or stress drop. Scaling exponents are determined using finite-size\nscaling for systems with thousands to millions of particles. Three distinct\nuniversality classes are identified corresponding to overdamped and underdamped\nlimits, as well as a crossover damping that separates the two regimes. For each\nuniversality class, the exponent describing the avalanche distributions is the\nsame in two and three dimensions. The spatial extent of plastic damage is\nproportional to the energy dissipated in an avalanche. Both rise much more\nrapidly with system size in the underdamped limit where inertia is important.\nInertia also lowers the mean energy of configurations sampled by the system and\nleads to an excess of large events like that seen in earthquake distributions\nfor individual faults. The distribution of stress values during shear narrows\nto zero with increasing system size and may provide useful information about\nthe size of elemental events in experimental systems. For overdamped and\ncrossover systems the stress variation scales inversely with the square root of\nthe system size. For underdamped systems the variation is determined by the\nsize of the largest events."
    },
    {
        "anchor": "Tests of Dynamical Scaling in 3-D Spinodal Decomposition: We simulate late-stage coarsening of a 3-D symmetric binary fluid. With\nreduced units l,t (with scales set by viscosity, density and surface tension)\nour data extends two decades in t beyond earlier work. Across at least four\ndecades, our own and others' individual datasets (< 1 decade each) show viscous\nhydrodynamic scaling (l ~ a + b t), but b is not constant between runs as this\nscaling demands. This betrays either the unexpected intrusion of a\ndiscretization (or molecular) lengthscale, or an exceptionally slow crossover\nbetween viscous and inertial regimes.",
        "positive": "A Maxwell Construction for Phase Separation in Vibrated Granular Matter?: Experiments and computer simulations are carried out to investigate ordering\nprinciples in a granular gas which phase separates under vibration. The\ndensities of the dilute and the dense phase are found to follow a lever rule. A\nMaxwell construction is found to predict both the coexisting pressure and\nbinodal densities remarkably well, despite the fact that the pressure-volume\ncharacteristic $P(v)$ is not an isotherm. Although the system is far from\nequilibrium and energy conservation is strongly violated, we derive the\nconstruction from the minimization of mechanical work and fluctuating particle\ncurrents."
    },
    {
        "anchor": "Curved geometries from planar director fields - Solving the\n  two-dimensional inverse problem: Thin nematic elastomers, composite hydrogels and plant tissues are among many\nsystems that display uniform anisotropic deformation upon external actuation.\nIn these materials, the spatial orientation variation of a local director field\ninduces intricate global shape changes. Despite extensive recent efforts, to\ndate, there is no general solution to the inverse design problem: how to design\na director field that deforms exactly into a desired surface geometry upon\nactuation, or whether such a field exists. In this work, we phrase this inverse\nproblem as a hyperbolic system of differential equations. We prove that the\ninverse problem is locally integrable, provide an algorithm for its\nintegration, and derive bounds on global solutions. We classify the set of\ndirector fields that deform into a given surface, thus paving the way to\nfinding optimized fields.",
        "positive": "Thermodynamic measurement of non-equilibrium stochastic processes in\n  optical tweezers: Due to their versatility in investigating phenomena in microscopic scales,\noptical tweezers have been an excellent platform for studying stochastic\nthermodynamics. In this context, this work presents experimental measurements\nof the energetic cost of driven finite-time protocols using colloidal Brownian\nparticles in harmonic potentials. For this simple model system, we compare the\nresults of optimal and sub-optimal protocols in a time-dependent trap,\ncontrolling the trap stiffness with different modulation amplitudes and\nprotocol times. We also calculate the Jarzynski relation for the stochastic\ntrajectories from the experimental data as an independent consistency check."
    },
    {
        "anchor": "Topology of the energy landscape of sheared amorphous solids and the\n  irreversibility transition: Recent experiments and simulations of amorphous solids plastically deformed\nby oscillatory drive have foundsurprising behavior - for small strain\namplitudes the dynamics can be reversible, which is contrary to the usual\nnotion of plasticity as an irreversible form of deformation. This reversibility\nallows the system to reach limit-cycles in which plastic events repeat\nindefinitely under the oscillatory drive. Reaching reversible limit-cycles, can\ntake a large number of driving cycles and it was surmised that the plastic\nevents encountered during the transient period are not encountered again and\nare thus irreversible. Using a graph representation of the stable\nconfigurations of the system and the plastic events connecting them, we show\nthat the notion of reversibility is more subtle. We find that reversible\nplastic events are abundant, and that a large portion of the plastic events\nencountered during the transient period are actually reversible, in the sense\nthat they can be part of a reversible deformation path. We observe that the\ntransition graph can be decomposed into clusters of configurations that are\nconnected by reversible transitions. These clusters are the strongly connected\ncomponents of the graph and their sizes turn out to be power-law distributed.\nThe largest of these are grouped in regions of reversibility, which in turn are\nconfined by regions of irreversibility whose number proliferates at larger\nstrains. Our results provide an explanation for the irreversibility transition\n- the divergence of the transient period at a critical forcing amplitude. Long\ntransients result from transition between clusters of reversibility in a search\nfor a cluster large enough to contain a limit-cycle of a specific amplitude.\nFor large enough amplitudes, the search time becomes very large, since sizes of\nthe limit cycles become incompatible with the sizes of the regions of\nreversibility.",
        "positive": "Beliaev Damping and Kelvin Mode Spectroscopy of a Condensate in the\n  Presence of a Vortex Line: It is demonstrated theoretically that the counter-rotating quadrupole mode in\na vortex of Bose-Einstein condensates can decay into a pair of Kelvin modes via\nBeliaev process. We calculate the spectral weight of density-response function\nwithin Bogoliubov framework, taking account of both Beliaev and Landau\nprocesses. Good agreement with experiment on $^{87}$Rb by Bretin et al.\n[cond-mat/0211101] allows us to unambigiously identify the decayed mode as the\nKelvin wave propagating along a vortex line."
    },
    {
        "anchor": "Nonlinear dynamics of a microswimmer in Poiseuille flow: We study the three-dimensional dynamics of a spherical microswimmer in\ncylindrical Poiseuille flow which can be mapped onto a Hamiltonian system.\nSwinging and tumbling trajectories are identified. In 2D they are equivalent to\noscillating and circling solutions of a mathematical pendulum. Hydrodynamic\ninteractions between the swimmer and confining channel walls lead to\ndissipative dynamics and result in stable trajectories, different for pullers\nand pushers. We demonstrate this behavior in the dipole approximation of the\nswimmer and with simulations using the method of multi-particle collision\ndynamics.",
        "positive": "dsDNA persistence length with divalent ions: Finding a theoretical formula for the persistence length of polyelectrolytes\nfor the whole experimental range of salt concentration is a long standing\nchallenge. Using the Tethered Particle Motion technique, the double-stranded\nDNA persistence length is measured for four monovalent and divalent salts on a\nthree-decade concentration range. The formula proposed by Trizac and Shen [EPL,\n116 18007 (2016)] and extended to divalent ions fits the data. This formula\nmixes the high salt limit solution of the Poisson-Boltzmann equation together\nwith the DNA charge renormalisation. Magnesium ions induce a fitted DNA radius\nsmaller than the geometrical one, consistent with a site-specific binding."
    },
    {
        "anchor": "Water Contribution to the Protein Folding and its Relevance in Protein\n  Design and Protein Aggregation: Water plays a fundamental role in protein stability. However, the effect of\nthe properties of water on the behaviour of proteins is only partially\nunderstood. Several theories have been proposed to give insight into the\nmechanisms of cold and pressure denaturation, or the limits of temperature and\npressure above which no protein has a stable, functional state, or how\nunfolding and aggregation are related. Here we review our results based on a\ntheoretical approach that can rationalise the water contribution to protein\nsolutions' free energy. We show, using Monte Carlo simulations, how we can\nrationalise experimental data with our recent results. We discuss how our\nfindings can help develop new strategies for the design of novel synthetic\nbiopolymers or possible approaches for mitigating neurodegenerative\npathologies.",
        "positive": "Simulation of Polyelectrolytes in Solution Using Dissipative Particle\n  Dynamics in the Grand Canonical Ensemble: Interaction Strength and Salt\n  Effects: We have studied a bulk electrolyte, and polyelectrolyte solutions with\nsurfactants or multivalent salt with the explicit presence of counterions and\nsolvent molecules by means of the mesoscopic dissipative particle dynamics\n(DPD) method in the Grand Canonical ensemble. The electrostatic interactions\nare calculated using the Ewald sum method and the structure of the fluid is\nanalyzed through the radial distribution function between charged particles.\nThe results are in very good agreement with those reported in the literature\nusing a different method for the calculation of the electrostatic forces, and\nwith those obtained using DPD in the canonical ensemble. We also studied the\nsalt dependent conformation of polyelectrolyte solutions as a function of the\nsolvent quality, and analyzed the electrostatic interaction strength dependence\nof dilute flexible polyelectrolytes in solution. For the complex systems\nmentioned above, the electrostatic interactions and the solvent quality play a\nkey role in understanding phenomena that do not occur in noncharged systems."
    },
    {
        "anchor": "Criticality and marginal stability of the shear jamming transition of\n  frictionless soft spheres: We study numerically the critical behavior and marginal stability of the\nshear jamming transition for frictionless soft spheres, observed to occur over\na finite range of densities, associated with isotropic jamming for densities\nabove the minimum jamming (J-point) density. Several quantities are shown to\nscale near the shear jamming point in the same way as the isotropic jamming\npoint. We compute the exponents associated with the small force distribution\nand the interparticle gap distribution,and show that the corresponding\nexponents are consistent with the marginal stability condition observed for\nisotropic jamming, and with predictions of the mean field theory of jamming in\nhard spheres.",
        "positive": "Lipids diffusion mechanism of stress relaxation in a bilayer fluid\n  membrane under pressure: A theory of a lateral stress relaxation in a fluid bilayer membrane under a\nstep-like pressure pulse is proposed. It is shown theoretically that transfer\nof lipid molecules into a strained region may lead to a substantial decrease of\nthe membrane's free energy due to local relaxation of the stress.\nSimultaneously, this same effect also causes appearance of the spontaneous\ncurvature of the membrane. Proposed stress relaxation mechanism may explain\nrecent experimental observations of a collapse of the ionic conductance through\nthe protein mechanosensitive channels piercing the E-coli's membrane. The\nconductance decreases within seconds after opening of the channels by applied\nexternal pressure. Theoretical estimates of the phospholipids diffusion time\ninside the strained area is favorably comparable with the experimental data.\nOur theory also predicts an increase of the membrane's curvature simultaneous\nwith the stress relaxation caused by the lipids diffusion. This effect is\nproposed for experimental check up of the theoretical predictions."
    },
    {
        "anchor": "Active Curved Polymers form Vortex Patterns on Membranes: Recent in vitro experiments with FtsZ polymers show self-organization into\ndifferent dynamic patterns, including structures reminiscent of the bacterial\nZ-ring. We model FtsZ polymers as active particles moving along chiral,\ncircular paths by Brownian dynamics simulations and a Boltzmann approach. Our\ntwo conceptually different methods point to a generic phase behavior. At\nintermediate particle densities, we find self-organization into vortex\nstructures including closed rings. Moreover, we show that the dynamics at the\nonset of pattern formation is described by a generalized complex\nGinzburg-Landau equation.",
        "positive": "Arrested dynamics of the dipolar hard-sphere model: We report the combined results of molecular dynamics simulations and\ntheoretical calculations concerning various dynamical arrest transitions in a\nmodel system representing a dipolar fluid, namely, N (softcore) rigid spheres\ninteracting through a truncated dipole-dipole potential. By exploring different\nregimes of concentration and temperature, we find three distinct scenarios for\nthe slowing down of the dynamics of the translational and orientational degrees\nof freedom: At low ({$\\eta$} = 0.2) and intermediate (${\\eta}$ = 0.4) volume\nfractions, both dynamics are strongly coupled and become simultaneously\narrested upon cooling. At high concentrations ({$\\eta$} $\\lt$ 0.6), the\ntranslational dynamics shows the features of an ordinary glass transition,\neither by compressing or cooling down the system, but with the orientations\nremaining ergodic, thus indicating the existence of partially arrested states.\nIn this density regime, but at lower temperatures, the relaxation of the\norientational dynamics also freezes. The physical scenario provided by the\nsimulations is discussed and compared against results obtained with the\nself-consistent generalized Langevin equation theory, and both provide a\nconsistent description of the dynamical arrest transitions in the system. Our\nresults are summarized in an arrested states diagram which qualitatively\norganizes the simulation data and provides a generic picture of the glass\ntransitions of a dipolar fluid."
    },
    {
        "anchor": "Kinetically driven ordered phase formation in binary colloidal crystals: The aggregation of binary colloids of same size and balanced charges is\nstudied by Brownian dynamics simulations for dilute suspensions. It is shown\nthat, under appropriate conditions, the formation of colloidal crystals is\ndominated by kinetic effects leading to the growth of well-ordered crystallites\nof the sodium-chloride (NaCl) bulk phase. These crystallites form with very\nhigh probability even when the cesium-chloride (CsCl) phase is more stable\nthermodynamically. Global optimization searches show that this result is not\nrelated to the most favorable structures of small clusters, that are either\namorphous or of CsCl structure. The formation of the NaCl phase is related to\nthe specific kinetics of the crystallization process, which takes place by a\ntwo-step mechanism. In this mechanism, dense fluid aggregates form at first and\nthen crystallization follows. It is shown that the type of short-range order in\nthese dense fluid aggregates determines which phase is finally formed in the\ncrystallites. The role of hydrodynamic effects in the aggregation process is\nanalyzed by Stochastic Rotation Dynamics - Molecular Dynamics simulations,\nfinding that these effects do not play a major role in the formation of the\ncrystallites.",
        "positive": "Obstructed swelling and fracture of hydrogels: Obstructions influence the growth and expansion of bodies in a wide range of\nsettings -- but isolating and understanding their impact can be difficult in\ncomplex environments. Here, we study obstructed growth/expansion in a model\nsystem accessible to experiments, simulations, and theory: hydrogels swelling\naround fixed cylindrical obstacles with varying geometries. When the obstacles\nare large and widely-spaced, hydrogels swell around them and remain intact. In\ncontrast, our experiments reveal that when the obstacles are narrow and\nclosely-spaced, hydrogels fracture as they swell. We use finite element\nsimulations to map the magnitude and spatial distribution of stresses that\nbuild up during swelling at equilibrium in a 2D model, providing a route toward\npredicting when this phenomenon of self-fracturing is likely to arise. Applying\nlessons from indentation theory, poroelasticity, and nonlinear continuum\nmechanics, we also develop a theoretical framework for understanding how the\nmaximum principal tensile and compressive stresses that develop during swelling\nare controlled by obstacle geometry and material parameters. These results thus\nhelp to shed light on the mechanical principles underlying growth/expansion in\nenvironments with obstructions."
    },
    {
        "anchor": "The effect of curvature and topology on membrane hydrodynamics: We study the mobility of extended objects (rods) on a spherical liquid-liquid\ninterface to show how this quantity is modified in a striking manner by both\nthe curvature and the topology of the interface. We present theoretical\ncalculations and experimental measurements of the interfacial fluid velocity\nfield around a moving rod bound to the crowded interface of a water-in-oil\ndroplet. By using different droplet sizes, membrane viscosities, and rod\nlengths, we show that the viscosity mismatch between the interior and exterior\nfluids leads to a suppression of the fluid flow on small droplets that cannot\nbe captured by the flat interface predictions.",
        "positive": "Growing timescales and lengthscales characterizing vibrations of\n  amorphous solids: Low-temperature properties of crystalline solids can be understood using\nharmonic perturbations around a perfect lattice, as in Debye's theory.\nLow-temperature properties of amorphous solids, however, strongly depart from\nsuch descriptions, displaying enhanced transport, activated slow dynamics\nacross energy barriers, excess vibrational modes with respect to Debye's theory\n(i.e., a Boson Peak), and complex irreversible responses to small mechanical\ndeformations. These experimental observations indirectly suggest that the\ndynamics of amorphous solids becomes anomalous at low temperatures. Here, we\npresent direct numerical evidence that vibrations change nature at a\nwell-defined location deep inside the glass phase of a simple glass former. We\nprovide a real-space description of this transition and of the rapidly growing\ntime and length scales that accompany it. Our results provide the seed for a\nuniversal understanding of low-temperature glass anomalies within the\ntheoretical framework of the recently discovered Gardner phase transition."
    },
    {
        "anchor": "Criticality in polar fluids: A model of polar fluid is studied theoretically. The interaction potential,\nin addition to dipole-dipole term, possesses a dispersion contribution of the\nvan der Waals-London form. It is found that when the dispersion force is\ncomparable to dipole-dipole interaction, the fluid separates into coexisting\nliquid and gas phases. The calculated critical parameters are in excellent\nagreement with Monte Carlo simulations. When the strength of dispersion\nattraction is bellow critical, no phase separation is found.",
        "positive": "Soft Granular Particles Sheared at a Controlled Volume: Rate-dependent\n  dynamics and the solid-fluid transition: We study the responses of fluid-immersed soft hydrogel spheres that are\nsheared under controlled volume fractions. Slippery, deformable particles along\nwith the density-matched interstitial fluid are sandwiched between two opposing\nrough cones, allowing studies for a wide range of volume fraction $\\phi$ both\nabove and below the jamming of granular suspension. We utilize sudden\ncessations of shearing, accompanied by refraction-matched internal imaging, to\nsupplement the conventional flow-curve measurements. At sufficiently high\nvolume fractions, the settling of particles after the cessations exhibits a\ncontinuous yet distinct transition over the change of shear rate. Such changes\nback out the qualitative difference in the state of flowing prior to the\ncessations: the quasi-static yielding of a tightly packed network, as opposed\nto the rapid sliding of particles mediated by the interstitial fluid whose\ndynamics depends on the driving rate. In addition, we determine the solid-fluid\ntransition using two independent methods: the extrapolation of stress residues\nand the estimated yield stress from high values of $\\phi$, and the settling of\nparticles upon shear cessations as $\\phi$ goes across the transition. We also\nverify the power law on values of characteristic stress with respect to the\ndistance from jamming $\\phi - \\phi_c$, with an exponent close to 2. These\nresults demonstrate a multitude of relaxation timescales behind the dynamics of\nsoft particles, and provoke questions on how we extend existing paradigms on\nthe flow of a densely packed system when the softness is actively involved."
    },
    {
        "anchor": "The dynamics of liquid 1-ethyl-3-methylimidazolium acetate measured with\n  implanted-ion $^8$Li $\u03b2$-NMR: We demonstrate the application of implanted-ion $\\beta$-detected NMR as a\nprobe of ionic liquid molecular dynamics through the measurement of $^8$Li\nspin-lattice relaxation (SLR) and resonance in 1-ethyl-3-methylimidazolium\nacetate. The motional narrowing of the resonance, and the local maxima in the\nSLR rate, $1/T_1$, imply a sensitivity to sub-nanosecond Li$^+$ solvation\ndynamics. From an analysis of $1/T_1$, we extract an activation energy ${E_A =\n74.8 \\pm 1.5}$ meV and Vogel-Fulcher-Tammann constant ${T_{\\mathrm{VFT}} =\n165.8 \\pm 0.9}$ K, in agreement with the dynamic viscosity of the bulk solvent.\nNear the melting point, the lineshape is broad and intense, and the form of the\nrelaxation is non-exponential, reflective of our sensitivity to heterogeneous\ndynamics near the glass transition. The depth resolution of this technique may\nlater provide a unique means of studying nanoscale phenomena in ionic liquids.",
        "positive": "Structural Order in Glassy Water: We investigate structural order in glassy water by performing classical\nmolecular dynamics simulations using the extended simple point charge (SPC/E)\nmodel of water. We perform isochoric cooling simulations across the glass\ntransition temperature at different cooling rates and densities. We quantify\nstructural order by orientational and translational order metrics. Upon cooling\nthe liquid into the glassy state, both the orientational order parameter $Q$\nand translational order parameter $\\tau$ increase. At T=0 K, the glasses fall\non a line in the $Q$-$\\tau$ plane or {\\it order map}.\n  The position of this line depends only on density and coincides with the\nlocation in the order map of the inherent structures (IS) sampled upon cooling.\nWe evaluate the energy of the IS, $e_{IS}(T)$, and find that both order\nparameters for the IS are proportional to $e_{IS}$. We also study the\nstructural order during the transformation of low-density amorphous ice (LDA)\nto high-density amorphous ice (HDA) upon isothermal compression and are able to\nidentify distinct regions in the order map corresponding to these glasses.\nComparison of the order parameters for LDA and HDA with those obtained upon\nisochoric cooling indicates major structural differences between glasses\nobtained by cooling and glasses obtained by compression. These structural\ndifferences are only weakly reflected in the pair correlation function. We also\ncharacterize the evolution of structural order upon isobaric annealing, leading\nat high pressure to very-high density amorphous ice (VHDA)."
    },
    {
        "anchor": "Diffusiophoretic propulsion of an isotropic active colloidal particle\n  near a finite-sized disk embedded in a planar fluid-fluid interface: Breaking spatial symmetry is an essential requirement for phoretic active\nparticles to swim at low Reynolds number. This fundamental prerequisite for\nswimming at the micro-scale is fulfilled either by chemical patterning of the\nsurface of active particles or alternatively by exploiting geometrical\nasymmetries to induce chemical gradients and achieve self-propulsion. In the\npresent manuscript, a far-field analytical model is employed to quantify the\nleading-order contribution to the induced phoretic velocity of a chemically\nhomogeneous isotropic active colloid near a finite-sized disk of circular shape\nresting on an interface separating two immiscible viscous incompressible\nNewtonian fluids. To this aim, the solution of the phoretic problem is\nformulated as a mixed-boundary-value problem which is subsequently transformed\ninto a system of dual integral equations on the inner and outer domains.\nDepending on the ratio of different involved viscosities and solute\nsolubilities, the sign of phoretic mobility and chemical activity, as well as\nthe ratio of particle-interface distance to the radius of the disk, the\nisotropic active particle is found to be either repelled from the interface,\nattracted to it, or reach a stable hovering state and remains immobile near the\ninterface. Our results may prove useful in controlling and guiding the motion\nof self-propelled phoretic active particles near aqueous interfaces.",
        "positive": "Particle contact dynamics as the origin for non-integer power expansion\n  rheology in attractive suspension networks: We show that Hertzian particle contacts are the underlying cause of the\nas-yet-unexplained noninteger power laws in weakly nonlinear rheology. In the\nmedium amplitude oscillatory shear (MAOS) region, the cubic scaling of the\nleading order nonlinear shear stress ($\\sigma_\\mathrm{3} \\sim\n\\gamma_\\mathrm{0}^{m_\\mathrm{3}}$, $m_\\mathrm{3}=3$) is the standard\nexpectation. Expanding on the work by Natalia et al. [J. Rheol. 64 625-635\n(2020)], we report an extensive data set of noncubical, noninteger power law\nscalings $m_\\mathrm{3}$ for particle suspensions in two immiscible fluids with\na capillary attractive interaction, known as capillary suspensions. Here, we\nshow that distinct power law exponents are found for the storage and loss\nmoduli and these noninteger scalings occur at every secondary fluid\nconcentration for two different contact angles. These compelling results\nindicate that the noninteger scalings are related to the underlying\nmicrostructure of capillary suspensions. We show that the magnitude of the\nthird harmonic elastic stress scaling $m_\\mathrm{3,elastic}$ originates from\nHertzian-like contacts in combination with the attractive capillary force. The\nrelated third harmonic viscous stress scaling $m_\\mathrm{3,viscous}$ is, found\nto be associated with adhesive-controlled friction. These observations,\nconducted for a wide range of compositions, can help explain previous reports\nof noninteger scaling for materials involving particle contacts and offers a\nnew opportunity using the variable power law exponent of MAOS rheology to\nreveal the physics of particle bonds and friction in the rheological response\nunder low deformation instead of at very high shear rates."
    },
    {
        "anchor": "Making the Cut: Lattice Kirigami Rules: In this paper we explore and develop a simple set of rules that apply to\ncutting, pasting, and folding honeycomb lattices. We consider origami-like\nstructures that are extinsically flat away from zero-dimensional sources of\nGaussian curvature and one-dimensional sources of mean curvature, and our\ncutting and pasting rules maintain the intrinsic bond lengths on both the\nlattice and its dual lattice. We find that a small set of rules is allowed\nproviding a framework for exploring and building kirigami -- folding, cutting,\nand pasting the edges of paper.",
        "positive": "Phase diagram of Gaussian-core nematics: We study a simple model of a nematic liquid crystal made of parallel\nellipsoidal particles interacting via a repulsive Gaussian law. After\nidentifying the relevant solid phases of the system through a careful\nzero-temperature scrutiny of as many as eleven candidate crystal structures, we\ndetermine the melting temperature for various pressure values, also with the\nhelp of exact free energy calculations. Among the prominent features of this\nmodel are pressure-driven reentrant melting and the stabilization of a columnar\nphase for intermediate temperatures."
    },
    {
        "anchor": "Collective mechano-response dynamically tunes cell-size distributions in\n  growing bacterial colonies: Mechanical stresses stemming from environmental factors are a key determinant\nof cellular behavior and physiology. Yet, the role of self-induced\nbiomechanical stresses in growing bacterial colonies has remained largely\nunexplored. Here, we demonstrate how collective mechanical forcing plays an\nimportant role in the dynamics of the cell size of growing bacteria. We observe\nthat the measured elongation rate of well-nourished \\textit{Escherichia coli}\ncells decreases over time, depending on the free area around each individual,\nand associate this behavior with the response of the growing cells to\nmechanical stresses. Via a cell-resolved model accounting for the feedback of\ncollective forces on individual cell growth, we quantify the effect of this\nmechano-response on the structure and composition of growing bacterial\ncolonies, including the local environment of each cell. Finally, we predict\nthat a mechano-cross-response between competing bacterial strains with distinct\ngrowth rates affects their size distributions.",
        "positive": "Mesoscopic Physics of Granular Flows: We present a description of granular dynamics based on the idea of\ndifferentiation between fluid and solid components. First, we construct a model\nof completely fluidized phase. Then we discuss a shear surface motion on the\nboundary of the bulk solid phase, induced by a moving wall. Our results include\nthe thickness dependence of the velocity of a developed avalanche, density and\nvelocity profiles in granular Couette flow experiment."
    },
    {
        "anchor": "Front instabilities in evaporatively dewetting nanofluids: Various experimental settings that involve drying solutions or suspensions of\nnanoparticles -- often called nanofluids -- have recently been used to produce\nstructured nanoparticle layers. In addition to the formation of polygonal\nnetworks and spinodal-like patterns, the occurrence of branched structures has\nbeen reported. After reviewing the experimental results we use a modified\nversion of the Monte Carlo model first introduced by Rabani et al. [Nature 426,\n271 (2003)] to study structure formation in evaporating films of nanoparticle\nsolutions for the case that all structuring is driven by the interplay of\nevaporating solvent and diffusing nanoparticles.\n  After introducing the model and its general behavior we focus on receding\ndewetting fronts which are initially straight but develop a transverse\nfingering instability. We analyze the dependence of the characteristics of the\nresulting branching patterns on the driving chemical potential, the mobility\nand concentration of the nanoparticles, and the interaction strength between\nliquid and nanoparticles. This allows us to understand the underlying\ninstability mechanism.",
        "positive": "Self-assembly of catalytically active colloidal molecules: Tailoring\n  activity through surface chemistry: A heterogeneous and dilute suspension of catalytically active colloids is\nstudied as a non-equilibrium analogue of ionic systems, which has the\nremarkable feature of action-reaction symmetry breaking. Symmetrically coated\ncolloids are found to join up to form self-assembled molecules that could be\ninert or have spontaneous activity in the form of net translational velocity\nand spin depending on their symmetry properties and their constituents. The\ntype of activity can be adjusted by changing the surface chemistry and ambient\nvariables that control the surface reactions and the phoretic drift."
    },
    {
        "anchor": "Interaction of Alamethicin Pores in DMPC Bilayers: We have investigated the x-ray scattering signal of highly aligned\nmultilayers of the zwitterionic lipid\n1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine containing pores formed by the\nantimicrobial peptide alamethicin as a function of the peptide/lipid ratio. We\nare able to obtain information on the structure factor of the pore fluid, which\nthen yields the interaction potential between pores in the plane of the\nbilayers. Aside from a hard core with a radius corresponding to the geometric\nradius of the pore, we find a repulsive lipid-mediated interaction with a range\nof $\\simeq 30$ {\\AA} and a contact value of 2.4 $k_BT$. This result is in\nqualitative agreement with recent theoretical models.",
        "positive": "Arrangement of DOBAMBC molecules inside the capsule on change of the\n  molecule's inclination on the border of the capsule investigated by the\n  molecular dynamics method: The method of molecular dynamics is used to investigate the distribution of\nDOBAMBC molecules in a capsule with the fixed border layer. Change of an\narrangement of molecules in smectic layers depending on an inclination of\nmolecules on border is considered."
    },
    {
        "anchor": "Scaling of the normal coefficient of restitution for wet impacts: A thorough understanding of the energy dissipation in the dynamics of wet\ngranular matter is essential for a continuum description of natural phenomena\nsuch as debris flow, and the development of various industrial applications\nsuch as the granulation process. The coefficient of restitution (COR), defined\nas the ratio between the relative rebound and impact velocities of a binary\nimpact, is frequently used to characterize the amount of energy dissipation\nassociated. We measure the COR by tracing a freely falling sphere bouncing on a\nwet surface with the liquid film thickness monitored optically. For fixed ratio\nbetween the film thickness and the particle size, the dependence of the COR on\nthe impact velocity and various properties of the liquid film can be\ncharacterized with the Stokes number, defined as the ratio between the inertia\nof the particle and the viscosity of the liquid. Moreover, the COR for\ninfinitely large impact velocities derived from the scaling can be analyzed by\na model considering the energy dissipation from the inertia of the liquid film.",
        "positive": "Packings of 3D stars: Stability and structure: We describe a series of experiments involving the creation of cylindrical\npackings of star-shaped particles, and an exploration of the stability of these\npackings. The stars cover a broad range of arm sizes and frictional properties.\nWe carried out three different kinds of experiments, all of which involve\ncolumns that are prepared by raining star particles one-by-one into hollow\ncylinders. As an additional part of the protocol, we sometimes vibrated the\ncolumn before removing the confining cylinder. We rate stability in terms of r,\nthe ratio of the mass of particles that fall off a pile when it collapsed, to\nthe total particle mass. The first experiment involved the intrinsic stability\nof the pile when the confining cylinder was removed. The second kind of\nexperiment involved adding a uniform load to the top of the column, and then\ndetermining the collapse properties. A third experiment involved testing\nstability to tipping of the piles. We find a stability diagram relating the\npile height, h, vs. pile diameter, delta, where the stable and unstable regimes\nare separated by a boundary that is roughly a power-law in h vs. delta with an\nexponent that is less than one. Increasing friction and vibration both tend to\nstabilize piles, while increasing particle size can destabilize the system\nunder certain conditions."
    },
    {
        "anchor": "Creases and cusps in growing soft matter: The buckling of a soft elastic sample under growth or swelling has\nhighlighted a new interest in materials science, morphogenesis, and biology or\nphysiology. Indeed, the change of mass or volume is a common fact of any living\nspecies, and on a scale larger than the cell size, a macroscopic view can help\nto explain many features of common observation. Many morphologies of soft\nmaterials result from the accumulation of elastic compressive stress due to\ngrowth, and thus from the minimization of a nonlinear elastic energy. The\nsimilarity between growth and compression of a piece of rubber has revived the\ninstability formalism of nonlinear elastic samples under compression, and in\nparticular Biot's instability. Here we present a modern treatment of this\ninstability in the light of complex analysis and demonstrate the richness of\npossible profiles that an interface can present under buckling, even if one\nrestricts oneself to the two spatial dimensions. Special attention is given to\nwrinkles, folds and cusps, a surprising observation in swelling gels or clays.\nThe standard techniques of complex analysis, nonlinear bifurcation theory and\npath-independent integrals are revisited to highlight the role of physical\nparameters at the origin of the observed patterns below and above the Biot\nthreshold.",
        "positive": "Continuum percolation and the liquid-solid coexistence line of simple\n  fluids: We compare the percolation loci for chemical clusters with the liquid-solid\ntransition in the temperature-density phase diagram. Chemical clusters are\ndefined as sets of particles connected through particle-particle bonds that\nlast for a given time tau. By using molecular dynamics simulations of a\nLennard-Jones system we obtain the percolation loci at different values of tau\nas the lines in the temperature-density plane at which the system presents a\nspanning cluster in 50 percent of the configurations. We find that the\npercolation loci for chemical clusters shifts rapidly towards high densities as\ntau is increased. For moderate values of tau this line coincides with the\nlow-density branch of the liquid-solid coexistence curve. This implies that no\nstable chemical clusters can be found in the fluid phase. In contrast, the\npercolation loci for physical clusters -sets of particles that remain close\ntogether at every instant for a given period tau- tends to a limiting line, as\ntau tends to infinity, which is far from the liquid-solid transition line."
    },
    {
        "anchor": "Directional drying of a colloidal dispersion: quantitative description\n  with water potential measurements using water clusters in a\n  poly(dimethylsiloxane) microfluidic chip: We have developed a poly(dimethylsiloxane) (PDMS) microfluidic chip to study\nthe directional drying of a colloidal dispersion confined in a channel. Our\nmeasurements on a dispersion of silica nanoparticles once again revealed the\nphenomenology commonly observed for such systems: the formation of a porous\nsolid with linear growth in the channel at short times, slowing down at longer\ntimes as the evaporation rate decreases. The growth of the solid is also\naccompanied by mechanical stresses that are released by the delamination of the\nsolid from the channel walls and the formation of cracks. In addition to these\nobservations, we report original measurements using hydrophilic filler in the\nPDMS formulation used (Sylgard-184). When the PDMS matrix is in contact with\nwater, water molecules pool around these hydrophilic sites, resulting in the\nformation of microscopic water clusters whose size depends on the water\npotential $\\psi$. In our work, we have used these water clusters to estimate\nthe water potential profile in the channel as the porous solid grows. Using a\ntransport model that also takes into account solid delamination in the channel,\nwe then linked these water potential measurements to the hydraulic permeability\nof the porous solid. These measurements finally enabled us to show that the\nslowdown in the evaporation rate is due to the invasion of the porous solid by\nair/water nanomenisci at a critical capillary pressure $\\psi_\\text{cap}$.",
        "positive": "Flexoelectric polarization in the biaxial nematic phase: The dipole flexoelectric (FE) polarization in liquid crystals is derived in\nthe thermodynamic limit at small distortions and small density. General\nmicroscopic expressions for the FE coefficients are obtained in the case of the\nuniaxial and biaxial nematic phases composed of C_2v molecules. The expressions\ninvolve the one-particle distribution function and the potential energy of\ntwo-body short-range interactions. In the case of the biaxial nematic phase,\nsix basic deformations produce FE polarization but there are only five\nindependent FE coefficients."
    },
    {
        "anchor": "Analytical approach to viscous fingering in a cylindrical Hele-Shaw cell: We report analytical results for the development of the viscous fingering\ninstability in a cylindrical Hele-Shaw cell of radius a and thickness b. We\nderive a generalized version of Darcy's law in such cylindrical background, and\nfind it recovers the usual Darcy's law for flow in flat, rectangular cells,\nwith corrections of higher order in b/a. We focus our interest on the influence\nof cell's radius of curvature on the instability characteristics. Linear and\nslightly nonlinear flow regimes are studied through a mode-coupling analysis.\nOur analytical results reveal that linear growth rates and finger competition\nare inhibited for increasingly larger radius of curvature. The absence of\ntip-splitting events in cylindrical cells is also discussed.",
        "positive": "Density fields for branching, stiff networks in rigid confining regions: We develop a formalism to describe the equilibrium distributions for segments\nof confined branched networks consisting of stiff filaments. This is applicable\nto certain situations of cytoskeleton in cells, such as for example actin\nfilaments with branching due to the Arp2/3 complex. We develop a grand ensemble\nformalism that enables the computation of segment density and polarisation\nprofiles within the confines of the cell. This is expressed in terms of the\nsolution to nonlinear integral equations for auxiliary functions. We find three\nspecific classes of behaviour depending on filament length, degree of branching\nand the ratio of persistence length to the dimensions of the geometry. Our\nmethod allows a numerical approach for semi-flexible filaments that are\nnetworked."
    },
    {
        "anchor": "Universal features in \"stickiness\" criteria for soft adhesion with rough\n  surfaces: A very interesting recent paper by Dalvi et al. has demonstrated convincingly\nwith adhesion experiments of a soft material with a hard rough material that\nthe simple energy idea of Persson and Tosatti works reasonably well, namely the\nreduction in apparent work of adhesion is equal to the energy required to\nachieve conformal contact. We demonstrate here that, in terms of a stickiness\ncriterion, this is extremely close to a criterion we derive from BAM (Bearing\nArea Model) of Ciavarella, and not very far from that of Violano et al. It is\nrather surprising that all these criteria give very close results and this also\nconfirms stickiness to be mainly dependent on macroscopic quantities.",
        "positive": "Slow dynamics in a single glass bead: Slow dynamic nonlinearity is ubiquitous amongst brittle materials, such as\nrocks and concrete, with cracked microstructures. A defining feature of the\nbehavior is the logarithmic-in-time recovery of stiffness after a mechanical\nconditioning. Materials observed to exhibit slow dynamics are sufficiently\ndifferent in microstructure, chemical composition, and scale (ranging from the\nlaboratory to the seismological) to suggest some kind of universality. There\nlacks a consensus theoretical understanding of the universality in general and\nthe log(time) recovery in particular. Seminal studies were focused on\nsandstones and other natural rocks, but in recent years other experimental\nvenues have been introduced with which to inform theory. One such system is\nunconsolidated glass bead packs. However, bead packs still contain many contact\npoints. The force distribution amongst the contacts is unknown. Here, we\npresent slow dynamics measurements on a yet simpler system - a single glass\nbead confined between two large glass plates. The system is designed with a\nview towards rapid control of the contact zone environment. Ultrasonic waves\nare used as a probe of the system, and changes are assessed with coda wave\ninterferometry. Three different methods of low-frequency conditioning are\napplied; all lead to slow dynamic recoveries. Results imply that force chains\ndo not play an essential role in granular media slow dynamics, as they are\nabsent in our system."
    },
    {
        "anchor": "Snapping elastic disks as microswimmers: swimming at low Reynolds\n  numbers by shape hysteresis: We illustrate a concept for shape-changing microswimmers, which exploits the\nhysteresis of a shape transition of an elastic object, by an elastic disk\nundergoing cyclic localized swelling. Driving the control parameter of a\nhysteretic shape transition in a completely time-reversible manner gives rise\nto a non-time-reversible shape sequence and a net swimming motion if the\nelastic object is immersed into a viscous fluid. We prove this concept with a\nmicroswimmer which is a flat circular elastic disk that undergoes a transition\ninto a dome-like shape by localized swelling of an inner disk. The control\nparameter of this shape transition is a scalar swelling factor of the disk\nmaterial. With a fixed outer frame with an additional attractive interaction in\nthe central region, the shape transition between flat and dome-like shape\nbecomes hysteretic and resembles a hysteretic opening and closing of a scallop.\nEmploying Stokesian dynamics simulations of a discretized version of the disk\nwe show that the swimmer is effectively moving into the direction of the\nopening of the dome in a viscous fluid if the swelling parameter is changed in\na time-reversible manner. The swimming mechanism can be qualitatively\nreproduced by a simple 9-bead model.",
        "positive": "Stick-release pattern in stretching single condensed polyelectrolyte\n  toroids: Using Langevin dynamics simulations, we study elastic response of single\nsemiflexible polyelectrolytes to an external force pulling on the chain ends,\nto mimic the stretching of DNA molecules by optical tweezers. The linear chains\nare condensed by multivalent counterions into toroids. The force-extension\ncurve shows a series of sawtooth-like structure, known as the stick-release\npatterns in experiments. We demonstrate that these patterns are a consequence\nof the loop-by-loop unfolding of the toroidal structure. Moreover, the\ndynamics, how the internal structure of chain varies under tension, is\nexamined. At the first stage of the stretching, the toroidal condensate\ndecreases its size until the loss of the first loop in the toroid and then,\noscillates around this size for the rest of the unfolding process. The normal\nvector of the toroid is pulled toward the pulling-force direction and swings\nback to its early direction repeatedly when the toroidal chain looses a loop.\nThe results provide new and valuable information concerning the elasticity and\nthe microscopic structure and dynamic pathway of salt-condensed DNA molecules\nbeing stretched."
    },
    {
        "anchor": "Active phase separation in mixtures of chemically interacting particles: We theoretically study mixtures of chemically-interacting particles, which\nproduce or consume a chemical to which they are attracted or repelled, in the\nmost general case of many coexisting species. We find a new class of active\nphase separation phenomena in which the nonequilibrium chemical interactions\nbetween particles, which break action-reaction symmetry, can lead to separation\ninto phases with distinct density and stoichiometry. Due to the generic nature\nof our minimal model, our results shed light on the underlying fundamental\nprinciples behind nonequilibrium self-organization of cells and bacteria,\ncatalytic enzymes, or phoretic colloids.",
        "positive": "Multistability of free spontaneously-curved anisotropic strips: Multistable structures are objects with more than one stable conformation,\nexemplified by the simple switch. Continuum versions are often elastic\ncomposite plates or shells, such as the common measuring tape or the slap\nbracelet, both of which exhibit two stable configurations: rolled and unrolled.\nHere we consider the energy landscape of a general class of multistable\nanisotropic strips with spontaneous Gaussian curvature. We show that while\nstrips with non-zero Gaussian curvature can be bistable, strips with positive\nspontaneous curvature are always bistable, independent of the elastic moduli,\nstrips of spontaneous negative curvature are bistable only in the presence of\nspontaneous twist and when certain conditions on the relative stiffness of the\nstrip in tension and shear are satisfied. Furthermore, anisotropic strips can\nbecome tristable when their bending rigidity is small. Our study complements\nand extends the theory of multistability in anisotropic shells and suggests new\ndesign criteria for these structures."
    },
    {
        "anchor": "Plants to Polyelectrolytes: Theophylline Polymers and their Microsphere\n  Synthesis: To extend fossil oil supplies, sustainable feed stocks for the production of\nuseful reagents and polymers should be harnessed. In this regard, chemicals\nderived from plants are excellent candidates. While the vast majority of plant\nsources used for polymer science only contain CxHyOz, alkaloids such as\ncaffeine, nicotine, and theophylline possess nitrogen functionality that can\nprovide new functions for bio-derived polymers and their synthesis. In this\ncontext, we exploited the chemistry of theophylline, a natural product found in\nchocolate and tea, to create a cationic poly(theophylline) in a straightforward\nfashion for the first time. We demonstrate how this new polymer can be\nsynthesized and used for the creation of narrowly disperse cationic\nmicrospheres.",
        "positive": "Forces exerted by a correlated fluid on embedded inclusions: We investigate the forces exerted on embedded inclusions by a fluid medium\nwith long-range correlations, described by an effective scalar field theory.\nSuch forces are the basis for the medium-mediated Casimir-like force. To study\nthese forces beyond thermal average, it is necessary to define them in each\nmicrostate of the medium. Two different definitions of these forces are\ncurrently used in the literature. We study the assumptions underlying them. We\nshow that only the definition that uses the stress tensor of the medium gives\nthe sought-after force exerted by the medium on an embedded inclusion. If a\nsecond inclusion is embedded in the medium, the thermal average of this force\ngives the usual Casimir-like force between the two inclusions. The other\ndefinition can be used in the different physical case of an object that\ninteracts with the medium without being embedded in it. We show in a simple\nexample that the two definitions yield different results for the variance of\nthe Casimir-like force."
    },
    {
        "anchor": "On the origins of apparent fragile-to-strong transition of protein\n  hydration waters: 2H NMR is used to study the mechanisms for the reorientation of protein\nhydration water. In the past, crossovers in temperature-dependent correlation\ntimes were reported at T_x1=225K (X1) and T_x2=200K (X2). We show that neither\nX1 nor X2 are related to a fragile-to-strong transition. Our results rule out\nan existence of X1. Also, they indicate that water performs thermally activated\nand distorted tetrahedral jumps at T<T_x2, implying that X2 originates in an\nonset of this motion, which may be related to a universal defect diffusion in\nmaterials with defined hydrogen-bond networks.",
        "positive": "The Origin of Tilted Phase Generation in Systems of Ellipsoidal\n  Molecules with Dipolar Interactions: We report Monte-Carlo simulation studies of some systems consisting of polar\nrod-like molecules interacting via a pair potential that exhibit liquid crystal\nphases, attributed with tilt angles of large magnitude. For theoretical\nunderstanding of the microscopic origin of the tilted phases, different systems\nconsisting of prolate ellipsoidal molecules of three different lengths,\nembedded with two symmetrically placed anti-parallel terminal dipoles are\nconsidered. We find that the presence of a stable tilted phase crucially\ndepends on the molecular elongation which effectively makes dipolar separation\nlonger. We observe that in case of mesogens with transverse dipoles the tilt in\nthe layered smectic phase gradually increases from zero to a large magnitude as\nwe increase the molecular length. However tilt remains weak with molecular\nelongation for systems with longitudinal dipoles which shows a small tilt at\nshorter lengths. This is the first work determining the combined contribution\nof dipolar separation and orientations in generating biaxial liquid crystal\nphases with large tilt angles."
    },
    {
        "anchor": "Interpretation of Elasticity of Liquid Marbles: Liquid marbles are non-stick droplets covered with micro-scaled particles.\nLiquid marbles demonstrate quasi-elastic properties when pressed. The\ninterpretation of the phenomenon of elasticity of liquid marbles is proposed.\nThe model considering the growth in the marble surface in the course of\ndeformation under the conservation of marbles volume explains\nsemi-quantitatively the elastic properties of marbles in satisfactory agreement\nwith the reported experimental data. The estimation of the effective Young\nmodulus of marbles and its dependence on the marble volume are reported.",
        "positive": "Segment Distribution around the Center of Gravity of a Triangular\n  Polymer: The segment distribution around the center of gravity is investigated for a\nspecial comb polymer (triangular polymer) having the side chains of the same\ngeneration number, $g$, as the main backbone. Common to all the other polymers,\nthe radial mass distribution is expressed as the sum of the distribution\nfunctions for the end-to-end vectors, $\\{\\vec{r}_{Gh}\\}$, from the center of\ngravity to the monomers on the $h$th generation; the result being, for a large\n$g$, \\begin{equation}\n\\varphi_{\\text{triang}}(s)=\\frac{1}{N}\\left\\{\\sum_{h=1}^{g}\\left(\\frac{d}{2\\pi\\left\\langle\nr_{Gh}^{2}\\right\\rangle}\\right)^{\\frac{d}{2}}\\text{Exp}\\left(-\\frac{d}{2\\left\\langle\nr_{Gh}^{2}\\right\\rangle}s^2\\right)+\\sum_{h=2}^{g}\\sum_{j=1}^{g-h}\\left(\\frac{d}{2\\pi\\left\\langle\nr_{Gh_{j}}^{2}\\right\\rangle}\\right)^{\\frac{d}{2}}\\text{Exp}\\left(-\\frac{d}{2\\left\\langle\nr_{Gh_{j}}^{2}\\right\\rangle}s^2\\right)\\right\\}\\notag \\end{equation} It is found\nthat the mean square of the radius of gyration varies as $\\left\\langle\ns_{N}^{2}\\right\\rangle_{0}\\doteq\\frac{7}{15}\\,g\\,l^{2}$, as\n$g\\rightarrow\\infty$. Since $g\\propto \\sqrt{N}$ for the triangular polymer,\nthis leads to $\\left\\langle s_{N}^{2}\\right\\rangle_{0}^{1/2}\\propto N^{1/4}$,\ngiving the same exponent as observed for the randomly branched polymer. On the\nbasis of the present result, we put forth that all the known polymers obey the\nequality: $\\left\\langle s_{N}^{2}\\right\\rangle_{0}=A\\, g\\,l^{2}$, where $A$ is\na polymer-species-dependent coefficient and also depends on the choice of the\nroot monomer. We discuss the extension of this empirical equation."
    },
    {
        "anchor": "Diffusion-Dominated Pinch-Off of Ultralow Surface Tension Fluids: We study the breakup of a liquid thread inside another liquid at different\nsurface tensions. In general, the pinch-off of a liquid thread is governed by\nthe dynamics of fluid flow. However, when the interfacial tension is ultralow\n(2 to 3 orders lower than normal liquids), we find that the pinch-off dynamics\ncan be governed by bulk diffusion. By studying the velocity and the profile of\nthe pinch-off, we explain why the diffusion-dominated pinch-off takes over the\nconventional breakup at ultralow surface tensions.",
        "positive": "Elastic constants from direct correlation functions in nematic liquid\n  crystals: a computer simulation study: Density functional theories such as the Poniewierski-Stecki theory relate the\nelastic properties of nematic liquid crystals with their local liquid\nstructure, i.e., with the direct correlation function (DCF) of the particles.\nWe propose a way to determine the DCF in the nematic state from simulations\nwithout any approximations, taking into account the dependence of pair\ncorrelations on the orientation of the director explicitly. Using this scheme,\nwe evaluate the Frank elastic constants K1, K2 and K3 in a system of soft\nellipsoids. The values are in good agreement with those obtained directly from\nan analysis of order fluctuations. Our method thus establishes a reliable way\nto calculate elastic constants from pair distributions in computer simulations."
    },
    {
        "anchor": "Visualizing kinetic pathways of homogeneous nucleation in colloidal\n  crystallization: When a system undergoes a transition from a liquid to a solid phase, it\npasses through multiple intermediate structures before reaching the final\nstate. However, our knowledge on the exact pathways of this process is limited,\nmainly due to the difficulty of realizing direct observations. Here, we\nexperimentally study the evolution of symmetry and density for various\ncolloidal systems during liquid-to-solid phase transitions, and visualize\nkinetic pathways with single-particle resolution. We observe the formation of\nrelatively-ordered precursor structures with different symmetries, which then\nconvert into metastable solids. During this conversion, two major\ncross-symmetry pathways always occur, regardless of the final state and the\ninteraction potential. In addition, we find a broad decoupling of density\nvariation and symmetry development, and discover that nucleation rarely starts\nfrom the densest regions. These findings hold for all our samples, suggesting\nthe possibility of finding a unified picture for the complex crystallization\nkinetics in colloidal systems.",
        "positive": "Level statistics and Anderson delocalization in two-dimensional granular\n  materials: Contrary to the theoretical predictions that all waves in two-dimensional\ndisordered materials are localized, Anderson localization is observed only for\nsufficiently high frequencies in an isotropically jammed two-dimensional\ndisordered granular packing of photoelastic disks. More specifically, we have\nperformed an experiment in analyzing the level statistics of normal mode\nvibrations. We observe delocalized modes in the low-frequency boson-peak regime\nand localized modes in the high frequency regime with the crossover frequency\njust below the Debye frequency. We find that the level-distance distribution\nobeys Gaussian-Orthogonal-Ensemble (GOE) statistics, i.e. Wigner-Dyson\ndistribution, in the boson-peak regime, whereas those in the high-frequency\nregime Poisson statistics is observed. The scenario is found to coincide with\nthat of harmonic vibrational excitations in three-dimensional disordered\nsolids."
    },
    {
        "anchor": "First-Order \"Hyper-selective\" Binding Transition of Multivalent\n  Particles Under Force: Multivalent particles bind to targets via many independent ligand-receptor\nbonding interactions. This microscopic design spans length scales in both\nsynthetic and biological systems. Classic examples include interactions between\ncells, virus binding, synthetic ligand-coated micrometer-scale vesicles or\nsmaller nano-particles, functionalised polymers, and toxins. Equilibrium\nmultivalent binding is a continuous yet super-selective transition with respect\nto the number of ligands and receptors involved in the interaction. Increasing\nthe ligand or receptor density on the two particles leads to sharp growth in\nthe number of bound particles at equilibrium.\n  Here we present a theory and Monte Carlo simulations to show that applying\nmechanical force to multivalent particles causes their adsorption/desorption\nisotherm on a surface to become sharper and more selective, with respect to\nvariation in the number of ligands and receptors on the two objects. When the\nforce is only applied to particles bound to the surface by one or more ligands,\nthen the transition can become infinitely sharp and first-order---a new binding\nregime which we term \"hyper-selective\". Force may be imposed by, e.g. flow of\nsolvent around the particles, a magnetic field, chemical gradients, or\ntriggered uncoiling of inert oligomers/polymers tethered to the particles to\nprovide a steric repulsion to the surface. This physical principle is a step\ntowards \"all or nothing\" binding selectivity in the design of multivalent\nconstructs.",
        "positive": "How active forces influence nonequilibrium glass transitions: Dense assemblies of self-propelled particles undergo a nonequilibrium form of\nglassy dynamics. Physical intuition suggests that increasing departure from\nequilibrium due to active forces fluidifies a glassy system. We falsify this\nbelief by devising a model of self-propelled particles where increasing\ndeparture from equilibrium can both enhance or depress glassy dynamics,\ndepending on the chosen state point. We analyze a number of static and dynamic\nobservables and suggest that the location of the nonequilibrium glass\ntransition is primarily controlled by the evolution of two-point static density\ncorrelations due to active forces. The dependence of the density correlations\non the active forces varies non-trivially with the details of the system, and\nis difficult to predict theoretically. Our results emphasize the need to\ndevelop an accurate liquid state theory for nonequilibrium systems."
    },
    {
        "anchor": "Thermal diffusion of supersonic solitons in an anharmonic chain of atoms: We study the non-equilibrium diffusion dynamics of supersonic lattice\nsolitons in a classical chain of atoms with nearest-neighbor interactions\ncoupled to a heat bath. As a specific example we choose an interaction with\ncubic anharmonicity. The coupling between the system and a thermal bath with a\ngiven temperature is made by adding noise, delta-correlated in time and space,\nand damping to the set of discrete equations of motion. Working in the\ncontinuum limit and changing to the sound velocity frame we derive a\nKorteweg-de Vries equation with noise and damping. We apply a collective\ncoordinate approach which yields two stochastic ODEs which are solved\napproximately by a perturbation analysis. This finally yields analytical\nexpressions for the variances of the soliton position and velocity. We perform\nLangevin dynamics simulations for the original discrete system which fully\nconfirm the predictions of our analytical calculations, namely noise-induced\nsuperdiffusive behavior which scales with the temperature and depends strongly\non the initial soliton velocity. A normal diffusion behavior is observed for\nvery low-energy solitons where the noise-induced phonons also make a\nsignificant contribution to the soliton diffusion.",
        "positive": "Interfacial separation between elastic solids with randomly rough\n  surfaces: comparison between theory and numerical techniques: We study the distribution of interfacial separations P(u) at the contact\nregion between two elastic solids with randomly rough surfaces. An analytical\nexpression is derived for P(u) using Persson's theory of contact mechanics, and\nis compared to numerical solutions obtained using (a) a half-space method based\non the Boussinesq equation, (b) a Green's function molecular dynamics technique\nand (c) smart-block classical molecular dynamics. Overall, we find good\nagreement between all the different approaches."
    },
    {
        "anchor": "Biofilm Growth Under Elastic Confinement: Bacteria often form surface-bound communities, embedded in a self-produced\nextracellular matrix, called biofilms. Quantitative studies of their growth\nhave typically focused on unconfined expansion above solid or semi-solid\nsurfaces, leading to exponential radial growth. This geometry does not\naccurately reflect the natural or biomedical contexts in which biofilms grow in\nconfined spaces. Here we consider one of the simplest confined geometries: a\nbiofilm growing laterally in the space between a solid surface and an overlying\nelastic sheet. A poroelastic framework is utilised to derive the radial growth\nrate of the biofilm; it reveals an additional self-similar expansion regime,\ngoverned by the stiffness of the matrix, leading to a finite maximum radius,\nconsistent with our experimental observations of growing $Bacillus~subtilis$\nbiofilms confined by PDMS.",
        "positive": "Heat conduction through a trapped solid: effect of structural changes on\n  thermal conductance: We study the conduction of heat across a narrow solid strip trapped by an\nexternal potential and in contact with its own liquid. Structural changes,\nconsisting of addition and deletion of crystal layers in the trapped solid, are\nproduced by altering the depth of the confining potential. Nonequilibrium\nmolecular dynamics simulations and, wherever possible, simple analytical\ncalculations are used to obtain the thermal resistance in the liquid, solid and\ninterfacial regions (Kapitza or contact resistance). We show that these\nlayering transitions are accompanied by sharp jumps in the contact thermal\nresistance. Dislocations, if present, are shown to increase the thermal\nresistance of the strip drastically."
    },
    {
        "anchor": "Density profiles of Ar adsorbed in slits of CO_2: spontaneous symmetry\n  breaking: A recently reported symmetry breaking of density profiles of fluid argon\nconfined by two parallel solid walls of carbon dioxide is studied. The\ncalculations are performed in the framework of a nonlocal density functional\ntheory. It is shown that the existence of such asymmetrical solutions is\nrestricted to a special choice for the adsorption potential, where the\nattraction of the solid-fluid interaction is reduced by the introduction of a\nhard-wall repulsion. The behavior as a function of the slit's width is also\ndiscussed. All the results are placed in the context of the current knowledge\non this matter.",
        "positive": "A Polymer Chain with Dipolar Active Forces in Connection to Spatial\n  Organization of Chromatin: A living cell is an active environment where the organization and dynamics of\nchromatin are affected by different forms of activity. Optical experiments\nreport that loci show subdiffusive dynamics and the chromatin fiber is seen to\nbe coherent over micrometer-scale regions. Using a bead-spring polymer chain\nwith dipolar active forces, we study how the subdiffusive motion of the loci\ngenerate large-scale coherent motion of the chromatin. We show that in the\npresence of extensile (contractile) activity, the dynamics of loci grows faster\n(slower) and the spatial correlation length increases (decreases) compared to\nthe case with no dipolar forces. Hence, both the dipolar active forces modify\nthe elasticity of the chain. Interestingly in our model, the dynamics and\norganization of such dipolar active chains largely differ from the passive\nchain with renormalized elasticity."
    },
    {
        "anchor": "A Thermodynamic Model for Prebiotic Protein Function: We propose a scenario for the prebiotic co-evolution of RNA and of fast\nfolding proteins with large entropy gaps as observed today. We show from very\ngeneral principles that the folding and unfolding of the proteins synthesized\nby RNA can function as a heat pump. Rock surfaces can facilitate the folding of\namino acid chains having polar and hydrophobic residues, with an accompanying\nheat loss to the surrounding rock. These chains then absorb heat from the soup\nas they unfold. This opens the way to the enhancement of RNA replication rates,\nby the enzymatic action of folded proteins present in greater numbers at\nreduced temperatures. This gives an evolutionary advantage to those RNA coding\namino acid sequences with non-degenerate folded states which would provide the\nmost efficient refrigeration.",
        "positive": "Distinct differences in the nanoscale behaviors of the twist-bend liquid\n  crystal phase of a flexible linear trimer and homologous dimer: We synthesized the liquid crystal dimer and trimer members of a series of\nflexible linear oligomers and characterized their microscopic and nanoscopic\nproperties using resonant soft x-ray scattering and a number of other\nexperimental techniques. On the microscopic scale, the twist-bend phases of the\ndimer and trimer appear essentially identical. However, while the liquid\ncrystal dimer exhibits a temperature-dependent variation of its twist-bend\nhelical pitch varying from 100 - 170 {\\AA} on heating, the trimer exhibits an\nessentially temperature-independent pitch of 66 {\\AA}, significantly shorter\nthan those reported for other twist-bend forming materials in the literature.\nWe attribute this to a specific combination of intrinsic conformational bend of\nthe trimer molecules and a sterically favorable intercalation of the trimers\nover a commensurate fraction (two-thirds) of the molecular length. We develop a\ngeometric model of the twist-bend phase for these materials with the molecules\narranging into helical chain structures, and we fully determine their\nrespective geometric parameters."
    },
    {
        "anchor": "Odd viscosity in chiral active fluids: Chiral active fluids are materials composed of self-spinning rotors that\ncontinuously inject energy and angular momentum at the microscale.\nOut-of-equilibrium fluids with active-rotor constituents have been\nexperimentally realized using nanoscale biomolecular motors, microscale active\ncolloids, or macroscale driven chiral grains. Here, we show how such chiral\nactive fluids break both parity and time-reversal symmetries in their steady\nstates, giving rise to a dissipationless linear-response coefficient called odd\nviscosity in their constitutive relations. Odd viscosity couples pressure and\nvorticity leading, for example, to density modulations within a vortex profile.\nMoreover, chiral active fluids flow in the direction transverse to applied\ncompression as in shock propagation experiments. We envision that this\ncollective transverse response may be exploited to design self-assembled\nhydraulic cranks that convert between linear and rotational motion in\nmicroscopic machines powered by active-rotors fluids.",
        "positive": "Can non-linear elasticity explain contact-line roughness at depinning?: We examine whether cubic non-linearities, allowed by symmetry in the elastic\nenergy of a contact line, may result in a different universality class at\ndepinning. Standard linear elasticity predicts a roughness exponent zeta=1/3\n(one loop), zeta=0.39 (numerics) while experiments give zeta of about 0.5.\nWithin functional RG we find that a non-local KPZ-type term is generated at\ndepinning and grows under coarse graining. A fixed point with zeta=0.45 (one\nloop) is identified, showing that large enough cubic terms increase the\nroughness. This fixed point is unstable, revealing a rough strong-coupling\nphase. Experimental study of contact angles theta near pi/2, where cubic terms\nvanish in the energy, is suggested."
    },
    {
        "anchor": "Compressive consolidation of strongly aggregated particle gels: The compressive yield stress of particle gels shows a highly nonlinear\ndependence on the packing fraction. We have studied continuous compression\nprocesses, and discussed the packing fraction dependence with the particle\nscale rearrangements. The 2D simulation of uniaxial compression was applied to\nfractal networks, and the required compressive stresses were evaluated for a\nwide range of packing fractions that approached close packing. The compression\nacts to reduce the size of the characteristic structural entities (i.e. the\ncorrelation length of the structure). We observed three stages of compression:\n(I) elastic-dominant regime; (II) single-mode plastic regime, where the network\nstrengths are determined by the typical length scale and the rolling mode; and\n(III) multi-mode plastic regime, where sliding mode and connection breaks are\nimportant. We also investigated the way of losing the fractal correlation under\ncompression. It turns out that both fractal dimension $D_{\\mathrm{f}}$ and\ncorrelation length $\\xi$ start to change from the early stage of compression,\nwhich is different from the usual assumption in theoretical models.",
        "positive": "Experimental Observation of Mesoscopic Fluctuations to Identify Origin\n  of Thermodynamic Anomalies of Ambient Liquid Water: We report a new experimental approach for observing mesoscopic fluctuations\nunderlying the thermodynamic anomalies of ambient liquid water. In this\napproach, two sound velocity measurements with different frequencies, namely\ninelastic X-ray scattering (IXS) in THz band and ultrasonic (US) in MHz band,\nare required to investigate the relaxation phenomenon with the characteristic\nfrequency between the two aforementioned frequencies. We performed IXS\nmeasurements to obtain the IXS sound velocity of liquid water from the ambient\nconditions to the supercritical region of liquid-gas phase transition (LGT) and\ncompared the results with the US sound velocity in the literature. We found\nthat the ratio of the two sound velocities, Sf, which corresponds to the\nrelaxation intensity, exhibits a simple but significant change. Two distinct\nrises were observed in the high-temperature and low-temperature regions,\nimplying that two relaxation phenomena exist: in the high-temperature region, a\npeak was observed near the LGT critical ridge line, which was linked with\nchanges in the density fluctuation and isochoric and isobaric specific heat\ncapacities; in the low-temperature region, Sf increased toward the\nlow-temperature region, which was linked with the change in the isochoric heat\ncapacity. We concluded that these two relaxation phenomena are originated from\ncritical fluctuations of liquid-gas phase transition (LGT) and liquid-liquid\nphase transition, respectively. The linkage between Sf and isochoric heat\ncapacity in the low-temperature region proves that the relaxation is the cause\nof the well-known heat capacity anomaly of ambient liquid water. In this study,\nboth LGT and LLT critical fluctuations were observed, and the relationship\nbetween thermodynamics and the critical fluctuations was comprehensively\ndiscussed."
    },
    {
        "anchor": "Non-native beta-sheet formation: insights into protein amyloidosis: Protein amyloidosis is a cytopathological process characterized by the\nformation of highly beta-sheet-rich fibrils. How this process occurs and how to\nprevent/treat the associated diseases are not completely understood. Here, we\ncarry out a theoretical investigation of sequence-independent beta-sheet\nformation, based on recent findings regarding the cooperativity of\nhydrogen-bond network formation. Our results strongly suggest that in vivo\nbeta-sheet aggregation is induced by inter-sheet stacking dynamics. This leads\nto a prediction for the minimal length of susceptible polymer needed to form\nsuch an aggregate. Remarkably, the prediction corresponds quite well with the\ncritical lengths detected in poly-glutamine-related diseases. Our work\ntherefore provides a theoretical framework capable of understanding the\nunderlying mechanism and shedding light on therapy strategies of protein\namyloidosis.",
        "positive": "Elastic director vibrations in nematic liquid crystals: Recently Biscari, DiCarlo and Turzi [\"Anisotropic wave propagation in nematic\nliquid crystals\", to appear (arXiv:1311.1802)] proposed a theory for\nnematoacustics which models nematic liquid crystals as nematic elastomers with\nmolecular relaxation. Here, we extend the analysis of this theory to account\nfor the director motion possibly induced by the propagation of a sound wave. We\nfind that the director vibration is related to the - usually small - anisotropy\nof the molecular distribution, thus providing a justification to the relative\nhigh ultrasonic intensities required to observe non-negligible acousto-optic\nresponses."
    },
    {
        "anchor": "Phase behaviour of deionized binary mixtures of charged colloidal\n  spheres: We review recent work on the phase behaviour of binary charged sphere\nmixtures as a function of particle concentration and composition. Both size\nratios and charge ratios are varied over a wide range. By contrast to hard\nspheres the long ranged Coulomb interaction stabilizes the crystal phase at low\nparticle concentrations and shifts the occurrence of amorphous solids to\nparticle concentrations considerably larger than the freezing concentration.\nDepending on size- and charge ratios we observe upper azeotrope, spindle, lower\nazeotrope and eutectic types of phase diagrams, all known well from metal\nsystems. Most solids are of body centred cubic structure. Occasionally\nstoichiometric compounds are formed at large particle concen-trations. For very\nlow size ratios entropic effects dominate and induce a fluid-fluid phase\nseparation. As for charged spheres also the charge ratio is decisive for the\ntype of phase behaviour, future experiments with charge variable silica spheres\nare suggested.",
        "positive": "Tunable Shear Thickening in Suspensions: Shear thickening, an increase of viscosity with shear rate, is a ubiquitous\nphenomena in suspended materials that has implications for broad technological\napplications. Controlling this thickening behavior remains a major challenge\nand has led to empirical strategies ranging from altering the particle surfaces\nand shape to modifying the solvent properties. However, none of these methods\nallow for tuning of flow properties during shear itself. Here, we demonstrate\nthat by strategic imposition of a high-frequency and low-amplitude shear\nperturbation orthogonal to the primary shearing flow, we can largely eradicate\nshear thickening. The orthogonal shear effectively becomes a regulator for\ncontrolling thickening in the suspension, allowing the viscosity to be reduced\nby up to two decades on demand. In a separate setup, we show that such effects\ncan be induced by simply agitating the sample transversely to the primary shear\ndirection. Overall, the ability of in situ manipulation of shear thickening\npaves a route towards creating materials whose mechanical properties can be\ncontrolled."
    },
    {
        "anchor": "Extremely fast simulations of heat transfer in fluidized beds: Besides their huge technological importance, fluidized beds have attracted a\nlarge amount of research because they are perfect playgrounds to investigate\nhighly dynamic particulate flows. Their over-all behavior is determined by\nshort-lasting particle collisions and the interaction between solid and gas\nphase. Modern simulation techniques that combine computational fluid dynamics\n(CFD) and discrete element methods (DEM) are capable of describing their\nevolution and provide detailed information on what is happening on the particle\nscale. However, these approaches are limited by small time steps and large\nnumerical costs, which inhibits the investigation of slower long-term processes\nlike heat transfer or chemical conversion.\n  In a recent study (Lichtenegger and Pirker, 2016), we have introduced\nrecurrence CFD (rCFD) as a way to decouple fast from slow degrees of freedom in\nsystems with recurring patterns: A conventional simulation is carried out to\ncapture such coherent structures. Their re-appearance is characterized with\nrecurrence plots that allow us to extrapolate their evolution far beyond the\nsimulated time. On top of these predicted flow fields, any passive or weakly\ncoupled process can then be investigated at fractions of the original\ncomputational costs.\n  Here, we present the application of rCFD to heat transfer in a lab-scale\nfluidized bed. Initially hot particles are fluidized with cool air and their\ntemperature evolution is recorded. In comparison to conventional CFD-DEM, we\nobserve speed-up factors of about two orders of magnitude at very good accuracy\nwith regard to recent measurements.",
        "positive": "Self-similar velocity and solid fraction profiles in silos with\n  eccentrically-located outlets: We examine the gravity-induced flow of dry and cohesionless granular media\nthrough an outlet placed eccentrically in a planar silo, employing computations\nbased on a soft-sphere discrete element method. The vertical velocity profiles,\nmeasured at the outlet, are self-similar when the eccentricity is given in\nterms of the gap ($s$) between the wall and the corner of the outlet nearest to\nthe wall. On the other hand, the self-similarity of vertical velocity does not\nalways hold for all eccentricities ($e$) given by the distance between the\ncenters of an outlet and the silo base, which is a typical metric of\neccentricity. Similar observations are noted for the profiles of solid\nfraction. For the former measure of eccentricity, the flow conditions are\nobserved to be similar for different outlet sizes. In contrast, we observe, the\nlatter leads to differing flow patterns for the highest eccentricity wherein\nthe largest outlet touches the sidewall and the rest are located at a distance.\nThis study establishes the importance of $s$ compared to $e$ from the viewpoint\nof the self-similarity of the vertical velocity and solid fraction profiles at\nthe outlet, and generalizes the notion of the scaling of velocity and solid\nfraction reported by Janda et al. [Phys. Rev. Lett. 108, 248001 (2012)] in a\nsilo with a centric exit to the one with eccentric granular discharge."
    },
    {
        "anchor": "Translational-Rotational Coupling during the Scattering of a Frictional\n  Sphere from a Flat Surface: At a macroscopic level, concepts such as top spin, back spin and rolling are\ncommonly used to describe the collision of balls and surfaces. Each term refers\nto an aspect of the coupling of rotational motion during the collision of a\nspherical particle with a planar surface. In this paper we explore the\nmechanisms of energy transfer involving the collision of a rotating sphere and\na surface using a model of frictional interactions developed for granular\nmaterial. We present explicit analytical treatments for the scattering and\nderive expressions for two important limiting classes: energy conserving\ncollisions and collisions subject to rapid transverse dissipation.",
        "positive": "Sharp and fast: Sensors and switches based on polymer brushes with\n  adsorption-active minority chains: We propose a design for polymer-based sensors and switches with sharp\nswitching transition and fast response time. The switching mechanism involves a\nradical change in the conformations of adsorption-active minority chains in a\nbrush. Such transitions can be induced by a temperature change of only about\nten degrees, and the characteristic time of the conformational change is less\nthan a second. We present an analytical theory for these switches and support\nit by self-consistent field calculations and Brownian dynamics simulations."
    },
    {
        "anchor": "Temporal Talbot effect in interference of matter waves from arrays of\n  Bose-Einstein condensates and transition to Fraunhofer diffraction: We consider interference patterns produced by coherent arrays of\nBose-Einstein condensates during their one-dimensional expansion. Several\ncharacteristic pattern structures are distinguished depending on value of the\nevolution time. Transformation of Talbot ``collapse-revival'' behavior to\nFraunhofer interference fringes is studied in detail.",
        "positive": "Phase separation in ordered polar active fluids: A new Universality\n  class: We show that phase separation in ordered polar active fluids belongs to a new\nuniversality class. This describes large collections of self-propelled entities\n(``flocks\"), all spontaneously moving in the same direction, in which\nattractive interactions (which can be caused by, e.g., autochemotaxis) cause\nphase separation: the system spontaneously separates into a high density band\nand a low density band, moving parallel to each other, and to the direction of\nmean flock motion, at different speeds. The upper critical dimension for this\ntransition is $d_c=5$, in contrast to the well-known $d_c=4$ of equilibrium\nphase separation. We obtain the large-distance, long-time scaling laws of the\nvelocity and density fluctuations, which are characterized by universal\ncritical correlation length and order parameter exponents $\\nu_\\perp$,\n$\\nu_\\parallel$ and $\\beta$ respectively. We calculate these to $\\mathcal{O}\n(\\epsilon)$ in a $d=5-\\epsilon$ expansion."
    },
    {
        "anchor": "Theoretical approaches to the structural properties of the\n  square-shoulder fluid: A comparison of simulation results with the prediction of the structural\nproperties of square-shoulder fluids is carried out to assess the performance\nof three theories: Tang--Lu's first-order mean spherical approximation, the\nsimplified exponential approximation of the latter and the rational-function\napproximation. These three theoretical developments share the characteristic of\nbeing analytical in Laplace space and of reducing in the proper limit to the\nPercus--Yevick result for the hard-sphere fluid. Overall, the best agreement\nwith the simulation data is obtained with the simplified exponential\napproximation.",
        "positive": "Controlling Solvent Quality by Time: Self-Avoiding Sprints in\n  Nonequilibrium Polymerization: A fundamental paradigm in polymer physics is that macromolecular\nconformations in equilibrium can be described by universal scaling laws, being\nkey for structure, dynamics, and function of soft (biological) matter and in\nthe materials sciences. Here, we reveal that during diffusion-influenced,\nnonequilibrium chain-growth polymerization, scaling laws change qualitatively,\nin particular, the growing polymers exhibit a surprising self-avoiding walk\n(SAW) behavior in poor and theta-solvents. Our analysis, based on\nmonomer-resolved reaction-diffusion computer simulations, demonstrates that\nthis phenomenon is a result of i) nonequilibrium monomer density depletion\ncorrelations around the active polymerization site, leading to a locally\ndirected and self-avoiding growth, in conjunction with ii) chain (Rouse)\nrelaxation times larger than the competing polymerization reaction time. These\nintrinsic nonequilibrium mechanisms are facilitated by fast and persistent\nreaction-driven diffusion (sprints) of the active site, with analogies to\npseudo-chemotactic active Brownian particles. Our findings have implications\nfor time-controlled structure formation in polymer processing, as in, e.g.,\nreactive self-assembly, photo-crosslinking, and 3D printing."
    },
    {
        "anchor": "Self-propulsion of a catalytically active particle near a planar wall:\n  from reflection to sliding and hovering: Micron-sized particles moving through solution in response to self-generated\nchemical gradients serve as model systems for studying active matter. Their\nfar-reaching potential applications will require the particles to sense and\nrespond to their local environment in a robust manner. The self-generated\nhydrodynamic and chemical fields, which induce particle motion, probe and are\nmodified by that very environment, including confining boundaries. Focusing on\na catalytically active Janus particle as a paradigmatic example, we predict\nthat near a hard planar wall such a particle exhibits several scenarios of\nmotion: reflection from the wall, motion at a steady-state orientation and\nheight above the wall, or motionless, steady \"hovering.\" Concerning the steady\nstates, the height and the orientation are determined both by the proportion of\ncatalyst coverage and the interactions of the solutes with the different\n\"faces\" of the particle. Accordingly, we propose that a desired behavior can be\nselected by tuning these parameters via a judicious design of the particle\nsurface chemistry.",
        "positive": "Role of $\u03b1$ and $\u03b2$ relaxations in Collapsing Dynamics of a\n  Polymer Chain in Supercooled Glass-forming Liquid: Understanding the effect of glassy dynamics on the stability of\nbio-macromolecules and investigating the underlying relaxation processes\ngoverning degradation processes of these macromolecules are of immense\nimportance in the context of bio-preservation. In this work we have studied the\nstability of a model polymer chain in a supercooled glass-forming liquid at\ndifferent amount of supercooling in order to understand how dynamics of\nsupercooled liquids influence the collapse behavior of the polymer. Our\nsystematic computer simulation studies find that apart from long time\nrelaxation processes ($\\alpha$ relaxation), short time dynamics of the\nsupercooled liquid, known as $\\beta$ relaxation plays an important role in\ncontrolling the stability of the model polymer. This is in agreement with some\nrecent experimental findings. These observations are in stark contrast with the\ncommon belief that only long time relaxation processes are the sole player. We\nfind convincing evidence that suggest that one might need to review the the\nvitrification hypothesis which postulates that $\\alpha$ relaxations control the\ndynamics of biomolecules and thus $\\alpha$-relaxation time should be considered\nfor choosing appropriate bio-preservatives. We hope that our results will lead\nto understand the primary factors in protein stabilization in the context of\nbio-preservation."
    },
    {
        "anchor": "Static wetting on deformable substrates, from liquids to soft solids: Young's law fails on soft solid and liquid substrates where there are\nsubstantial deformations near the contact line. On liquid substrates, this is\ncaptured by Neumann's classic analysis, which provides a geometrical\nconstruction for minimising the interfacial free energy. On soft solids, the\ntotal free energy includes an additional contribution from elasticity. A\nlinear-elastic model incorporating an out-of-plane restoring force due to solid\nsurface tension was recently shown to accurately predict the equilibrium shape\nof a thin elastic film due to a large sessile droplet. Here, we extend this\nmodel to find substrate deformations due to droplets of arbitrary size. While\nthe macroscopic contact angle matches Young's law for large droplets, it\nmatches Neumann's prediction for small droplets. The cross-over droplet size is\nroughly given by the ratio of the solid's surface tension and elastic modulus.\nAt this cross-over, the macroscopic contact angle increases, indicating that\nthe substrate is effectively less wetting. For droplets of all sizes, the\nmicroscopic behaviour near the contact line follows the Neumann construction\ngiving local force balance.",
        "positive": "Block Copolymer Films with Free Interfaces: Ordering by Nano-Patterned\n  Substrates: We study block copolymers (BCP) on patterned substrates, where the top\npolymer film surface is not constrained but is a free interface that adapts its\nshape self-consistently. In particular, we investigate the combined effect of\nthe free interface undulations with the wetting of the BCP film as induced by\nnano-patterned substrates. For a finite volume of BCP material, we find\nequilibrium droplets composed of coexisting perpendicular and parallel lamellar\ndomains. The self-assembly of BCP on topographic patterned substrates was also\ninvestigated and it was found that the free interface induces mixed\nmorphologies of parallel and perpendicular domains coupled with a non-flat free\ninterface. In both cases, the free interface relaxes the strong constraints\nthat would otherwise be imposed by a fixed top boundary (which is commonly used\nin simulations), and affects strongly the BCP ordering. Our study has some\ninteresting consequences for experimental setups of graphoepitaxy and\nnanoimprint lithography."
    },
    {
        "anchor": "Imaging the emergence of bacterial turbulence: phase diagram and\n  transition kinetics: We experimentally study the emergence of collective bacterial swimming, a\nphenomenon often referred to as bacterial turbulence. A phase diagram of the\nflow of 3D E. coli suspensions spanned by bacterial concentration, the swimming\nspeed of bacteria and the number fraction of active swimmers is systematically\nmapped, which shows quantitative agreement with kinetic theories and\ndemonstrates the dominant role of hydrodynamic interactions in bacterial\ncollective swimming. More importantly, we trigger bacterial turbulence by\nsuddenly increasing the swimming speed of light-powered bacteria and image the\ntransition to the turbulence in real time. Our experiments identify two unusual\nkinetic pathways, i.e., the one-step transition with long incubation periods\nnear the phase boundary and the two-step transition driven by long-wavelength\ninstabilities deep inside the turbulent phase. Our study provides not only a\nquantitative verification of existing theories, but also new insights into\ninterparticle interactions and transition kinetics of bacterial turbulence.",
        "positive": "An extended analysis of the viscosity kernel for monatomic and diatomic\n  fluids: We present an extended analysis of the wave-vector dependent shear viscosity\nof monatomic and diatomic (liquid chlorine) fluids over a wide range of\nwave-vectors and for a variety of state points. The analysis is based on\nequilibrium molecular dynamics simulations, which involves the evaluation of\ntransverse momentum density and shear stress autocorrelation functions. For\nliquid chlorine we present the results in both atomic and molecular formalisms.\nWe find that the viscosity kernel of chlorine is statistically\nindistinguishable with respect to atomic and molecular formalisms. The results\nfurther suggest that the real space viscosity kernels of monatomic and diatomic\nfluids depends sensitively on the density, the potential energy function and\nthe choice of fitting function in reciprocal space. It is also shown that the\nreciprocal space shear viscosity data can be fitted to two different simple\nfunctional forms over the entire density, temperature and wave-vector range: a\nfunction composed of n-Gaussian terms and a Lorentzian type function. Overall,\nthe real space viscosity kernel has a width of 3 to 6 atomic diameters which\nmeans that the generalized hydrodynamic constitutive relation is required for\nfluids with strain rates that vary nonlinearly over distances of the order of\natomic dimensions."
    },
    {
        "anchor": "Extension of the Hamaneh - Taylor model using the macroscopic\n  polarization for the description of chiral smectic liquid crystals: Chiral smectic liquid crystals exhibit a series of phases, including\nferroelectric, antiferroelectric and ferrielectric commensurate structures as\nwell as an incommensurate SmCalpha phase. We carried out an extension of the\nphenomenological model, recently presented by M. B. Hamaneh and P. L. Taylor,\nbased upon the distorted clock model.",
        "positive": "Active Matter Transport and Jamming on Disordered Landscapes: We numerically examine the transport of active run-and-tumble particles\ndriven with a drift force over random disordered landscapes comprised of fixed\nobstacles. For increasing run lengths, the net particle transport initially\nincreases before reaching a maximum and decreasing at larger run lengths. The\ntransport reduction is associated with the formation of cluster or living\ncrystal states that become locally jammed or clogged by the obstacles. We also\nfind that the system dynamically jams at lower particle densities when the run\nlength is increased. Our results indicate that there is an optimal activity\nlevel for active matter transport through quenched disorder, and could be\nimportant for understanding biological transport in complex environments or for\napplications of active matter particles in random media."
    },
    {
        "anchor": "Impact of bending stiffness on ground-state conformations for\n  semiflexible polymers: Many variants of RNA, DNA, and even proteins can be considered semiflexible\npolymers, where bending stiffness, as a type of energetic penalty, competes\nwith attractive van der Waals forces in structure formation processes. Here, we\nsystematically investigate the effect of the bending stiffness on ground-state\nconformations of a generic coarse-grained model for semiflexible polymers. This\nmodel possesses multiple transition barriers. Therefore, we employ advanced\ngeneralized-ensemble Monte Carlo methods to search for the lowest-energy\nconformations. As the formation of distinct versatile ground-state\nconformations, including compact globules, rod-like bundles, and toroids,\nstrongly depends on the strength of the bending restraint, we also performed a\ndetailed analysis of contact and distance maps.",
        "positive": "Scaling Laws of Stress and Strain in Brittle Fracture: A numerical realization of an elastic beam lattice is used to obtain scaling\nexponents relevant to the extent of damage within the controlled, catastrophic\nand total regimes of mode-I brittle fracture. The relative fraction of damage\nat the onset of catastrophic rupture approaches a fixed value in the continuum\nlimit. This enables disorder in a real material to be quantified through its\nrelationship with random samples generated on the computer."
    },
    {
        "anchor": "Polyelectrolyte Layer-by-Layer Assembly from Self-Consistent Field\n  Calculations: We have modeled the layer-by-layer assembly process of flexible\npolyelectrolytes on flat surfaces. The multilayer has a three-zone structure.\nAn exponential growth is found for the first several layers, followed by a\nlinear growth for subsequent layers evolving towards a steady state. While\nadjacent layers are highly interpenetrating, stratification can be seen for\nevery four or more layers. The effects of surface charge density, bulk salt\nconcentration, and solvent quality on the thickness and internal structure of\nthe multilayer are also studied. Our results agree with experimental findings.",
        "positive": "Structural characterisation of polycrystalline colloidal monolayers in\n  the presence of aspherical impurities: Impurities in crystalline materials introduce disorder into an otherwise\nordered structure due to the formation of lattice defects and grain boundaries.\nThe properties of the resulting polycrystal can differ remarkably from those of\nthe ideal single crystal. Here we investigate a quasi-two-dimensional system of\ncolloidal spheres containing a small fraction of aspherical impurities and\ncharacterise the resulting polycrystalline monolayer. We find that, in the\nvicinity of an impurity, the underlying hexagonal lattice is deformed due to a\npreference for 5-fold co-ordinated particles adjacent to impurities. This\nresults in a reduction in local hexagonal ordering around an impurity.\nIncreasing the concentration of impurities leads to an increase in the number\nof these defects and consequently a reduction in system-wide hexagonal ordering\nand a corresponding increase in entropy as measured from the distribution of\nVoronoi cell areas. Furthermore, through both considering orientational\ncorrelations and directly identifying crystalline domains we observe a decrease\nin the average polycrystalline grain size on increasing the concentration of\nimpurities. Our data show that, for the concentrations considered, local\nstructural modifications due to the presence of impurities are independent of\ntheir concentration, while structure on longer lengthscales (i.e. the size of\npolycrystalline grains) is determined by the impurity concentration."
    },
    {
        "anchor": "Note: Simple argument for emergent anisotropic stress correlations in\n  disordered solids: It is now well-established that mechanical equilibrium in athermal disordered\nsolids gives rise to anisotropic spatial correlations of the coarse-grained\nstress field that decay in space as $1/r^d$, where $r$ is the distance from the\norigin, and $d$ denotes the spatial dimension. In this note we present a\nsimple, geometry based argument for the scaling form of the emergent spatial\ncorrelations of the stress field in disordered solids.",
        "positive": "Scaling state of dry two-dimensional froths: universal angle deviations\n  and structure: We characterize the late-time scaling state of dry, coarsening,\ntwo-dimensional froths using a detailed, force-based vertex model. We find that\nthe slow evolution of bubbles leads to systematic deviations from 120degree\nangles at three-fold vertices in the froth, with an amplitude proportional to\nthe vertex speed, v ~ sqrt(t), but with a side-number dependence that is\nindependent of time. We also find that a significant number of T1\nside-switching processes occur for macroscopic bubbles in the scaling state,\nthough most bubble annihilations involve four-sided bubbles at microscopic\nscales."
    },
    {
        "anchor": "Slow closure of denaturation bubbles in DNA: twist matters: The closure of long equilibrated denaturation bubbles in DNA is studied using\nBrownian dynamics simulations. A minimal mesoscopic model is used where the\ndouble-helix is made of two interacting bead-spring freely rotating strands,\nwith a non-zero torsional modulus in the duplex state, $\\kappa_\\phi=$200 to 300\nkT. For DNAs of lengths N=40 to 100 base-pairs (bps) with a large initial\nbubble in their middle, long closure times of 0.1 to 100 microseconds are\nfound. The bubble starts winding from both ends until it reaches a 10 bp\nmetastable state. The final closure is limited by three competing mechanisms\ndepending on $\\kappa_\\phi$ and N: arms diffusion until their alignment, bubble\ndiffusion along the DNA until one end is reached, or local Kramers process\n(crossing over a torsional energy barrier). For clamped ends or long DNAs, the\nclosure occurs via this latter temperature activated mechanism, yielding for\nthe first time a good quantitative agreement with experiments.",
        "positive": "Optical analysis of spatially periodic patterns in nematic liquid\n  crystals: diffraction and shadowgraphy: Optical methods are most convenient to analyze spatially periodic patterns\nwith wavevector $\\bm q$ in a thin layer of a nematic liquid crystal. In the\nstandard experimental setup a beam of parallel light with a 'short' wavelength\n$\\lambda \\ll 2 \\pi/q$ passes the nematic layer. Recording the transmitted light\nthe patterns are either directly visualized by shadowgraphy or characterized\nmore indirectly by the diffraction fringes due to the optical grating effects\nof the pattern. In this work we present a systematic short-wavelength analysis\nof these methods for the commonly used planar orientation of the optical axis\nof liquid crystal at the confining surfaces. Our approach covers general 3D\nexperimental geometries with respect to the relative orientation of $\\bm q$ and\nof the wavevector $\\bm k$ of the incident light. In particular the importance\nof phase grating effects is emphasized, which are not accessible in a pure\ngeometric optics approach. Finally, as a byproduct we present also an optical\nanalysis of convection rolls in Rayleigh-B\\'enard convection, where the\nrefraction index of the fluid is isotropic in contrast to its uniaxial symmetry\nin nematic liquid crystals. Our analysis is in excellent agreement with an\nearlier physical optics approach by Trainoff and Cannell [Physics of Fluids\n{\\bf 14}, 1340 (2002)], which is restricted to a 2D geometry and technically\nmuch more demanding."
    },
    {
        "anchor": "Nonlinear response of the magnetophoresis in inverse ferrofluids: Taking into account the structural transition and long-range interaction\n(lattice effect), we resort to the Ewald-Kornfeld formulation and developed\nMaxwell-Garnett theory for uniaxially anisotropic suspensions to calculate the\neffective permeability of inverse ferrofluids. And we also consider the effect\nof volume fraction to the magnetophoretic force on the nonmagnetic spherical\nparticles submerged in ferrofluids in the presence of nonuniform magnetic\nfield. We find that the coupling of ac and dc field case can lead to\nfundamental and third harmonic response in the effective magnetophoresis and\nchanging the aspect ratio in both prolate and oblate particles can alter the\nharmonic and nonharmonic response and cause the magnetophoretic force vanish.",
        "positive": "Detachment of a rigid flat punch from a viscoelastic material: We show that the detachment of a flat punch from a viscoelastic substrate has\na relatively simple behavior, framed between the Kendall's elastic solution at\nthe relaxed modulus and at the instantaneous modulus, and the cohesive strength\nlimit. We find hardly any dependence of the pull-off force on the details of\nthe loading process, including maximum indentation at preload and loading rate,\nresulting much simpler than the case of a spherical punch. Pull-off force peaks\nat the highest speeds of unloading, when energy dissipation is negligible,\nwhich seems to be in contrast with what suggested by the theories originated by\nde Gennes of viscoelastic semi-infinite crack propagation which associated\nenhanced work of adhesion to dissipation. Further qualitative differences with\nthe dissipation-based model occur to explain the finite size effect."
    },
    {
        "anchor": "Chiral motion in colloidal electrophoresis: Asymmetrically charged, nonspherical colloidal particles in general perform\ncomplex rotations and oblique motions under an electric field. The interplay of\nelectrostatic and hydrodynamic forces complicate the prediction of these\nmotions. We demonstrate a method of calculating the body tensors that dictate\ntranslational and rotational velocity vectors arising from an external electric\nfield. We treat insulating, rigid bodies in the linear-response regime, with\nindefinitely small electrostatic screening length. The method represents the\nbody as an assembly of point sources of both hydrodynamic drag and surface\nelectric field. We demonstrate agreement with predicted electrophoretic\nmobility to within a few percent for several shapes with uniform and nonuniform\ncharge. We demonstrate strong chiral twisting motions for colloidal bodies of\nsymmetrical realistic shapes. The method applies more generally to active\ncolloidal swimmers.",
        "positive": "Combined thermal and particle shape effects on powder spreading in\n  additive manufacturing via discrete element simulations: The thermal and mechanical behaviors of powders are important for various\nadditive manufacturing technologies. For powder bed fusion, capturing the\ntemperature profile and the packing structure of the powders prior to melting\nis challenging due to both the various pathways of heat transfer and the\ncomplicated properties of powder system. Furthermore, these two effects can be\ncoupled due to the temperature dependence of particle properties. This study\naddresses this challenge using a discrete element model that simulates\nnon-spherical particles with thermal properties in powder spreading. Thermal\nconduction and radiation are introduced to a multi-sphere particle formulation\nfor capturing the heat transfer among irregular-shaped powders, which have\ntemperature-dependent elastic properties. The model is utilized to simulate the\nspreading of pre-heated PA12 powder through a hot substrate representing the\npart under manufacturing. Differences in the temperature profiles were found in\nthe spreading cases with different particle shapes, spreading speed, and\ntemperature dependence of the elastic moduli. The temperature of particles\nbelow the spreading blade is found to be dependent on the kinematics of the\nheap of particles in front, which eventually is influenced by the\ntemperature-dependent properties of the particles."
    },
    {
        "anchor": "Theory of polymer diffusion in polymer-nanoparticle mixtures: effect of\n  nanoparticle concentration and polymer length: The dynamics of polymer-nanoparticle (NP) mixtures, which involves multiple\nscales and system-specific variables, has posed a long-standing challenge on\nits theoretical description. In this paper, we construct a microscopic theory\nfor polymer diffusion in the mixtures based on a combination of generalized\nLangevin equation, mode-coupling approach, and polymer physics ideas. The\nparameter-free theory has an explicit expression and remains tractable on pair\ncorrelation level with system-specific equilibrium structures as input. Taking\na minimal polymer-NP mixture as an example, our theory correctly captures the\ndependence of polymer diffusion on NP concentration and average interparticle\ndistance. Importantly, the polymer diffusion exhibits a power law decay as the\npolymer length increases at dense NPs and/or long chain, which marks the\nemergence of entanglement-like motion. The work provides a first-principle\ntheoretical foundation to investigate dynamic problems in diverse polymer\nnanocomposites.",
        "positive": "On the stress overshoot in cluster crystals under shear: Using non-equilibrium molecular dynamics simulations we study the yielding\nbehaviour of a model cluster crystal formed by ultrasoft particles under shear.\nWe investigate the evolution of stress as a function of strain for different\nshear rates, $\\dot{\\gamma}$, and temperatures. The stress-strain relation\ndisplays a pronounced maximum at the yielding point; the height of this\nmaximum, $\\sigma_\\text{p}$, increases via a power law with an increasing shear\nrange and tends to saturate to a finite value if the limit shear rate goes to\nzero (at least within the considered temperature range). Interestingly, this\nbehaviour can be captured by the Herschel-Bulkley type model which, for a given\ntemperature, allows us to predict a static yield stress $\\sigma^{0}_\\text{p}$\n(in the shear rate tending to zero limit), a characteristic timescale\n$\\tau_\\text{c}$, and the exponent $\\alpha$ of the above-mentioned power-law\ndecay of the $\\sigma_\\text{p}$ at high shear rates. Furthermore, for different\ntemperatures, the $\\sigma_\\text{p}$ can be scaled as functions of\n$\\dot{\\gamma}$ onto a single master curve when scaled by corresponding\n$\\tau_\\text{c}$ and ${\\sigma}_\\text{p}^{0}$. Moreover, for a given shear rate,\n$\\sigma_\\text{p}$ displays a logarithmic dependence on temperature. Again, the\n$\\sigma_\\text{p}{-}T$ curves for different shear rates can be scaled on a\nsingle logarithmic master curve when scaled by a corresponding fitting\nparameters."
    },
    {
        "anchor": "Nonmonotonic Aging and Memory in a Frictional Interface: We measure the static frictional resistance and the real area of contact\nbetween two solid blocks subjected to a normal load. We show that following a\ntwo-step change in the normal load the system exhibits nonmonotonic aging and\nmemory effects, two hallmarks of glassy dynamics. These dynamics are strongly\ninfluenced by the discrete geometry of the frictional interface, characterized\nby the attachment and detachment of unique microcontacts. The results are in\ngood agreement with a theoretical model we propose that incorporates this\ngeometry into the framework recently used to describe Kovacs-like relaxation in\nglasses as well as thermal disordered systems. These results indicate that a\nfrictional interface is a glassy system and strengthen the notion that\nnonmonotonic relaxation behavior is generic in such systems.",
        "positive": "Exploiting Localized Transition Waves to Tune Sound Propagation in Soft\n  Materials: Programmable materials hold great potential for many applications such as\ndeployable structures, soft robotics, and wave control, however, the presence\nof instability and disorder might hinder their utilization. Through a\ncombination of analytical, numerical, and experimental analyses, we harness the\ninterplay between instabilities, geometric frustration, and mechanical\ndeformations to control the propagation of sound waves within self-assembled\nsoft materials. We consider levitated magnetic disks confined by a magnetic\nboundary in-plane. The assemblies can be either ordered or disordered depending\non the intrinsic disk symmetry. By applying an external load to the assembly,\nwe observe the nucleation and propagation of different topological defects\nwithin the lattices. In the presence of instabilities, the defect propagation\ngives rise to time-independent localized transition waves. Surprisingly, in the\npresence of frustration, the applied load briefly introduces\ndeformation-induced order to the material. By further deforming the lattices,\nnew patterns emerge across all disk symmetries. We utilize these patterns to\ntune sound propagation through the material. Our findings could open new\npossibilities for designing exotic materials with potential applications\nranging from sound control to soft robotics."
    },
    {
        "anchor": "Classical nucleation theory of ice nucleation: second-order correction\n  of thermodynamic parameters: Accurate estimate of nucleation rate is crucial for the study of ice\nnucleation and ice-promoting/anti-freeze strategies. Within the framework of\nClassical Nucleation Theory (CNT), the estimate of ice nucleation rate is very\nsensitive to thermodynamic parameters, such as chemical potential difference\nbetween water and ice $\\Delta \\mu$ and ice-water interfacial free energy\n$\\gamma$. However, even today, there are still many contradictions and\napproximations in the estimating of these thermodynamic parameters, introducing\nlarge uncertainty to the estimate of the ice nucleation rate. Herein, starting\nfrom the basic concepts, for a general solid-liquid crystallization system, we\nexpand the Gibbs-Thomson (GT) equation to second order, and derive the\nsecond-order analytical formulas of $\\Delta \\mu$, $\\gamma$ and nucleation\nbarrier $\\Delta G$ with combining molecular dynamics (MD) simulations. These\nformulas describe well the temperature dependence of these thermodynamic\nparameters. Our results can provide a method of estimating $\\Delta \\mu$,\n$\\gamma$ and $\\Delta G$.",
        "positive": "Translocation through conical pores: A direction-dependent process: The transport of biomolecules across a cell membrane is an important\nphenomena that plays a pivotal role in the functioning of biological cells. In\nthis paper, we investigate such processes by modeling the translocation of\npolymers through a conical channel, directed from the wider opening to the\nnarrow end of the conical channel. We use the molecular dynamics approach to\nstudy the problem. The effect of the different conical pore geometry and\npolymer lengths on translocation dynamics is determined from the behavior of\nthe total translocation time, $\\tau$, and waiting time distributions, $w(s)$.\nThe escape of polymer segments from the narrow end of the conical channel is\ntracked by studying their velocity profile ($v_{s}$). To demonstrate the\nasymmetric pore effects on the translocation dynamics, we compare the\ntranslocation process from both the ends of the conical channel. We find\nstriking differences in the translocation dynamics for both processes, which\nare in agreement with the experimental study. We have accounted the effect of\nvarious rigidity, and increasing length of a polymer chain, on both types of\nprocesses. The study can be used to find the transition from a directional\ndependent to a directional independent translocation process through a\nasymmetric channel."
    },
    {
        "anchor": "The dynamics of a self-phoretic Janus swimmer near a wall: We study the effect of a nearby planar wall on the propulsion of a phoretic\nJanus micro-swimmer driven by asymmetric reactions on its surface which absorb\nreactants and generate products. We show that the behaviour of these swimmers\nnear a wall can be classified ${\\bf based \\ on \\ whether}$ the swimmers are\n${\\bf mainly}$ absorbing or producing reaction solutes ${\\bf and \\ whether}$\ntheir swimming directions are such that the inert or active face is at the\nfront. We find that the wall-induced solute gradients always promote swimmer\npropulsion along the wall while the effect of hydrodynamics leads to\nre-orientation of the swimming direction away from the wall.",
        "positive": "Collective Diffusion of Colloidal Hard Rods in Smectic Liquid Crystals:\n  Effect of Particle Anisotropy: We study the layer-to-layer diffusion in smectic-A liquid crystals of\ncolloidal hard rods with different length-to-diameter ratios using computer\nsimulations. The layered arrangement of the smectic phase yields a hopping-type\ndiffusion due to the presence of permanent barriers and transient cages.\nRemarkably, we detect stringlike clusters composed of inter-layer rods moving\ncooperatively along the nematic director. Furthermore, we find that the\nstructural relaxation in equilibrium smectic phases shows interesting\nsimilarities with that of out-of-equilibrium supercooled liquids, although\nthere the particles are kinetically trapped in transient rather than permanent\ncages. Additionally, at fixed packing fraction we find that the barrier height\nincreases with increasing particle anisotropy, and hence the dynamics is more\nheterogeneous and non-Gaussian for longer rods, yielding a lower diffusion\ncoefficient along the nematic director and smaller clusters of inter-layer\nparticles that move less cooperatively. At fixed barrier height, the dynamics\nbecomes more non-Gaussian and heterogeneous for longer rods that move more\ncollectively giving rise to a higher diffusion coefficient along the nematic\ndirector."
    },
    {
        "anchor": "Borosilicones and viscoelastic silicone rubbers: network liquids and\n  network solids: Borosilicones (e.g., Silly Putty) have been known for 70 years, but their\npeculiar behaviors have remain unexplained. In this work, experiment and theory\nare used to show that they are network liquids---dynamic macromolecules that\nappear elastic on short timescales but exhibit flow on longer timescales. Each\nborosilicone is a vast covalent network of silicone polymer chains joined by\ntrifunctional boron crosslinks. At any instant, the borosilicone is a\nhighly-crosslinked elastic material. Because the boron crosslinks are\ntemporary, however, the network evolves with time and the borosilicone exhibits\nliquid behavior. A simple borosilicone exemplifies a classic transient network\nmodel and behaves as a simple (Lodge) elastic fluid. Its measured moduli and\nviscosities fit those predicted by the transient network model and the Maxwell\nviscoelastic model: a spring in series with a dashpot, including the observed\nexponential relaxation processes. When a borosilicone includes permanent\ncrosslinks, however, it no longer behaves as a simple elastic fluid. Its\nmeasured moduli and viscosities fit those predicted by the Fractional Maxwell\nviscoelastic model: a spring in series with a the spring-pot, including the\nobserved slower-than-exponential relaxation processes. Beyond the gelation\nthreshold, a borosilicone becomes a viscoelastic silicone rubber (VSR). With a\npermanent network that spans the material coupled to a temporary network that\nalso spans the material, the VSR is a network liquid piggybacking on a network\nsolid. The Fractional Zener viscoelastic model: an elastic spring in parallel\nto the Fractional Maxwell model, accurately predicts the measured moduli of\nVSRs. The temporary nature of boron crosslinks is due to exchange reactions.\nBecause the mean lifetime of temporary crosslinks is a borosilicone's only\nsignificant timescale, it exhibits thermo-rheological simplicity.",
        "positive": "Encounter dynamics of a small target by a polymer diffusing in a\n  confined domain: We study the first passage time for a polymer, that we call the narrow\nencounter time (NETP), to reach a small target located on the surface of a\nmicrodomain. The polymer is modeled as a Freely Joint Chain (beads connected by\nsprings with a resting non zero length) and we use Brownian simulations to\nstudy two cases: when (i) any of the monomer or (ii) only one can be absorbed\nat the target window. Interestingly, we find that {in the first case} the NETP\nis an increasing function of the polymer length until a critical length, after\nwhich it decreases. Moreover, in the long polymer regime, we identified an\nexponential scaling law for the NETP as a function of the polymer length. {In\nthe second case, the position of the absorbed monomer along the polymer chain\nstrongly influences the NETP}. Our analysis can be applied to estimate the mean\nfirst time of a DNA fragment to a small target in the chromatin structure or\nfor mRNA to find a small target."
    },
    {
        "anchor": "Persistent Homology and Many-Body Atomic Structure for Medium-Range\n  Order in the Glass: Characterization of medium-range order in amorphous materials and its\nrelation to short-range order is discussed. A new topological approach is\npresented here to extract a hierarchical structure of amorphous materials,\nwhich is robust against small perturbations and allows us to distinguish it\nfrom periodic or random configurations. The method is called the persistence\ndiagram (PD) and it introduces scales into many-body atomic structures in order\nto characterize the size and shape. We first illustrate how perfect crystalline\nand random structures are represented in the PDs. Then, the medium-range order\nin the amorphous silica is characterized by using the PD. The PD approach\nreduces the size of the data tremendously to much smaller geometrical summaries\nand has a huge potential to be applied to broader areas including complex\nmolecular liquid, granular materials, and metallic glasses.",
        "positive": "A model for cage formation in colloidal suspension of laponite: In this paper we investigate glass transition in aqueous suspension of\nsynthetic hectorite clay, laponite. We believe that upon dispersing laponite\nclay in water, system comprises of clusters (agglomerates) of laponite\ndispersed in the same. Subsequent osmotic swelling of these clusters leads to\nincrease in their volume fraction. We propose that this phenomenon is\nresponsible for slowing down of the overall dynamics of the system. As clusters\nfill up the space, system undergoes glass transition. Along with the mode\ncoupling theory, proposed mechanism rightly captures various characteristic\nfeatures of the system in the ergodic regime as it approaches glass transition."
    },
    {
        "anchor": "On stretch-limited elastic strings: Motivated by the increased interest in modeling nondissipative materials by\nconstitutive relations more general than those from Cauchy elasticity, we\ninitiate the study of a class of stretch-limited elastic strings: the string\ncannot be compressed smaller than a certain length less than its natural length\nnor elongated larger than a certain length greater than its natural length. In\nparticular, we consider equilibrium states for a string suspended between two\npoints under the force of gravity (catenaries). We study the locations of the\nsupports resulting in tensile states containing both extensible and\ninextensible segments in two situations: the degenerate case when the string is\nvertical and the nondegenerate case when the supports are at the same height.\nWe then study the existence and multiplicity of equilibrium states in general\nwith multiplicity differing markedly from strings satisfying classical\nconstitutive relations.",
        "positive": "Orientational transition in nanobridges of nematic liquid crystals in\n  slit pores: In this work, the morphology of nematic capillary nanobridges in slit pores\nseparated by a vertical distance $D$ will be characterised by Monte Carlo\nsimulations for oblate molecules nematogen modelled by the Gay-Berne potential.\nPrevious studies on droplets show that the molecules are arranged\nhomeotropically at the nematic-vapour interface and form spherical droplets\nwith an annular disclination located in their equatorial plane. In the presence\nof pores with attractive substrates that favour homeotropic anchoring, the\nformation of nanobridges characterised by anchoring angles that decrease with\nincreasing particle-substrate interaction intensity is observed. When the\norientational field in the nanobridge is analysed, the formation of an annular\ndisclination of topological charge $+1/2$ located in the plane perpendicular to\nthe $z$-axis that passes through the centre of mass of the nanobridge is\nobserved for small $D$. However, when considering higher values of $D$, a\nchange to a biaxial orientational profile within the nanobridge is observed,\nwhere now the annular disclination is arranged in a plane perpendicular to one\ndirection of the $xy$ plane. These results are indicative of the existence of\nan orientational phase transition for an intermediate $D$ value between a\nuniaxial and a biaxial orientational configuration in the capillary nanobridge."
    },
    {
        "anchor": "A model for the contraction kinetics of cytoskeletal gel slabs: Cytoskeletal gels are engineered prototypes that mimic the contractile\nbehavior of a cell in-vitro. They are composed of an active polymer matrix and\na liquid solvent. Their contraction kinetics is governed by two dynamic\nphenomena: mechanotransduction (molecular motor activation), and solvent\ndiffusion. In this paper, we solve the transient problem for the simple case of\na thin gel slab in uniaxial contraction under two extreme conditions:\nmotor-limited or slow motor activation (SM) regime, and diffusion-limited or\nfast motor activation (FM) regime. The former occurs when diffusion is much\nfaster than mechanotransduction, while the latter occurs in the opposite case.\nWe observe that in the SM regime, the contraction time scales as t/t_0 ~\n(l/l_0)^(-3), with t_0 the nominal contraction time, and l and l_0 are the\nfinal and initial stretches of the slab. t_0 is proportional to 1/w, where w is\nthe average mechanical power generated by the molecular motors per unit\nreference (dry polymer) volume. In the FM regime, the contraction time scales\nas t/t_1 ~ (1-l/l_0)^2, with t_1 the nominal contraction time, here\nproportional to the ratio L^2/D, where L is the reference (dry polymer)\nthickness, and D is the diffusivity of the solvent in the gel. The transition\nbetween the SM and FM regimes is defined by a characteristic power density w^*,\nwhere w << w^* gives the SM regime and w >> w^* gives the FM regime.\nIntuitively, w^* is proportional to D/L^2, where, at a given power density w, a\nthinner gel slab (smaller L) or including smaller solvent molecules (higher D)\nis more likely to be in the SM regime given that solvent diffusion will occur\nfaster than motor activation.",
        "positive": "Influence of sequence correlations on the adsorption of random\n  copolymers onto homogeneous planar surfaces: Using a reference system approach, we develop an analytical theory for the\nadsorption of random heteropolymers with exponentially decaying and/or\noscillating sequence correlations on planar homogeneous surfaces. We obtain a\nsimple equation for the adsorption-desorption transition line. This result as\nwell as the validity of the reference system approach is tested by a comparison\nwith numerical lattice calculations."
    },
    {
        "anchor": "A systematic study of the isothermal crystallization of the mono-alcohol\n  n-butanol monitored by dielectric spectroscopy: Isothermal crystallization of the mono-hydroxyl alcohol n-butanol was studied\nwith dielectric spectroscopy in real time. The crystallization was carried out\nusing two different sample cells at 15 temperatures between 120 K and 134 K.\nFor all temperatures, a shift in relaxation times to shorter times was observed\nduring the crystallization process, which is characterized by a drop in\nrelaxation strength. The two different sample environments induced quite\ndifferent crystallization behaviors, consistent and reproducible over all\nstudied temperatures. An explanation for the difference was proposed on the\nbackground of an Avrami and a Maxwell-Wagner analysis. Both types analysis\nsuggest that the morphology of the crystal growth changes at a point during the\ncrystallization. The differences between the cells can be explained by this\ntransition taking place at different times for the two cells.",
        "positive": "Lateral transport of domains in anionic lipid bilayer membranes under DC\n  electric fields: A coarse-grained molecular dynamics study: Dynamic lateral transport of lipids, proteins, and self-assembled structures\nin biomembranes plays crucial roles in diverse cellular processes. In this\nstudy, we perform a coarse-grained molecular dynamics simulation on a vesicle\ncomposed of a binary mixture of neutral and anionic lipids to investigate the\nlateral transport of individual lipid molecules and the self-assembled lipid\ndomains upon an applied direct current (DC) electric field. Under the potential\nforce of the electric field, a phase-separated domain rich in the anionic\nlipids is trapped in the opposite direction of the electric field. The\nsubsequent reversal of the electric field induces the unidirectional domain\nmotion. During the domain motion, the domain size remains constant, but a\nconsiderable amount of the anionic lipids is exchanged between the\nanionic-lipid-rich domain and the surrounding bulk. While the speed of the\ndomain motion (collective lipid motion) shows a significant positive\ncorrelation with the electric field strength, the exchange of anionic lipids\nbetween the domain and bulk (individual lipid motion) exhibits no clear\ncorrelation with the field strength. The mean velocity field of the lipids\nsurrounding the domain displays a two-dimensional (2D) source dipole. We\nrevealed that the balance between the potential force of the applied electric\nfield and the quasi-2D hydrodynamic frictional force well explains the\ndependence of the domain motions on the electric-field strengths. The present\nresults provide insight into the hierarchical dynamic responses of\nself-assembled lipid domains to the applied electric field and contribute to\ncontrolling the lateral transportation of lipids and membrane inclusions."
    },
    {
        "anchor": "Numerical Study of a Microscopic Artificial Swimmer: We present a detailed numerical study of a microscopic artificial swimmer\nrealized recently by Dreyfus et al. in experiments [R. Dreyfus et al., Nature\n437, 862 (2005)]. It consists of an elastic filament composed of\nsuperparamagnetic particles that are linked together by DNA strands. Attached\nto a load particle, the resulting swimmer is actuated by an oscillating\nexternal magnetic field so that it performs a non-reciprocal motion in order to\nmove forward. We model the superparamagnetic filament by a bead-spring\nconfiguration that resists bending like a rigid rod and whose beads experience\nfriction with the surrounding fluid and hydrodynamic interactions with each\nother. We show that, aside from finite-size effects, its dynamics is governed\nby the dimensionless sperm number, the magnitude of the magnetic field, and the\nangular amplitude of the field's oscillating direction. Then we study the mean\nvelocity and the efficiency of the swimmer as a function of these parameters\nand the size of the load particle. In particular, we clarify that the real\nvelocity of the swimmer is influenced by two main factors, namely the shape of\nthe beating filament (determined by the sperm number and the magnetic-field\nstrength) and the oscillation frequency. Furthermore, the load size influences\nthe performance of the swimmer and has to be chosen as a compromise between the\nlargest swimming velocity and the best efficiency. Finally, we demonstrate that\nthe direction of the swimming velocity changes in a symmetry-breaking\ntransition when the angular amplitude of the field's oscillating direction is\nincreased, in agreement with experiments.",
        "positive": "Pattern-induced local symmetry breaking in active matter systems: The emergence of macroscopic order and patterns is a central paradigm in\nsystems of (self-)propelled agents, and a key component in the structuring of\nmany biological systems.The relationships between the ordering process and the\nunderlying microscopic interactions have been extensively explored both\nexperimentally and theoretically. While emerging patterns often show one\nspecific symmetry (e.g. nematic lane patterns or polarized traveling flocks),\ndepending on the symmetry of the alignment interactions patterns with different\nsymmetries can apparently coexist. Indeed, recent experiments with an actomysin\nmotility assay suggest that polar and nematic patterns of actin filaments can\ninteract and dynamically transform into each other. However, theoretical\nunderstanding of the mechanism responsible remains elusive. Here, we present a\nkinetic approach complemented by a hydrodynamic theory for agents with mixed\nalignment symmetries, which captures the experimentally observed phenomenology\nand provides a theoretical explanation for the coexistence and interaction of\npatterns with different symmetries. We show that local, pattern-induced\nsymmetry breaking can account for dynamically coexisting patterns with\ndifferent symmetries. Specifically, in a regime with moderate densities and a\nweak polar bias in the alignment interaction, nematic bands show a local\nsymmetry-breaking instability within their high-density core region, which\ninduces the formation of polar waves along the bands. These instabilities\neventually result in a self-organized system of nematic bands and polar waves\nthat dynamically transform into each other. Our study reveals a mutual feedback\nmechanism between pattern formation and local symmetry breaking in active\nmatter that has interesting consequences for structure formation in biological\nsystems."
    },
    {
        "anchor": "Fluid-solid transition in hard hyper-sphere systems: In this work we present a numerical study, based on molecular dynamics\nsimulations, to estimate the freezing point of hard spheres and hypersphere\nsystems in dimension D = 4, 5, 6 and 7. We have studied the changes of the\nRadial Distribution Function (RDF) as a function of density in the coexistence\nregion. We started our simulations from crystalline states with densities above\nthe melting point, and moved down to densities in the liquid state below the\nfreezing point. For all the examined dimensions (including D = 3) it was\nobserved that the height of the first minimum of the RDF changes in an almost\ncontinuous way around the freezing density and resembles a second order phase\ntransition. With these results we propose a numerical method to estimate the\nfreezing point as a function of the dimension D using numerical fits and\nsemiempirical approaches. We find that the estimated values of the freezing\npoint are very close to previously reported values from simulations and\ntheoretical approaches up to D = 6 reinforcing the validity of the proposed\nmethod. This was also applied to numerical simulations for D = 7 giving new\nestimations of the freezing point for this dimensionality.",
        "positive": "Structure of nanoscale-pitch helical phases: blue phase and twist-bend\n  nematic phase resolved by resonant soft X-ray scattering: Periodic structures of phases with orientational order of molecules, but\nhomogenous electron density distribution: a short pitch cholesteric, blue phase\nand twist-bend nematic phase, were probed by a resonant soft x-ray scattering\n(RSoXS) at the carbon K-edge. The theoretical model shows that in case of a\nsimple heliconical nematic structure two resonant signals corresponding to the\nfull and half pitch band should be present, while only the full pitch band is\nobserved in experiment. This suggests that the twist-bend nematic phase has\ncomplex structure with a double-helix, built of two interlocked, shifted\nhelices. We confirm that the helical pitch in the twist-bend nematic phase is\nin a 10 nm range, for both, the chiral and achiral materials. We also show that\nthe symmetry of a blue phase can unambiguously be determined through a resonant\nenhancement of x-ray diffraction signals, by including polarization effects,\nwhich are found to be an important indicator in phase structure determination."
    },
    {
        "anchor": "Finite Elasticity of the Vertex Model and its Role in Rigidity of Curved\n  Cellular Tissues: Using a mean field approach and simulation, we study the non-linear\nmechanical response of the vertex model (VM) of biological tissue under\ncompression and dilation. The VM is known to exhibit a transition between rigid\nand fluid-like, or floppy, states driven by geometric incompatibility. Target\nperimeter and area set a target shape which may not be geometrically\nachievable, thereby engendering frustration. Previously, an asymmetry in the\nlinear elastic response was identified at the rigidity transition between\ncompression and dilation. Here we show and characterize how the asymmetry\nextends away from the transition point for finite strains. Under finite\ncompression, an initially solid VM can totally relax perimeter tension, and\nthereby have reduced bulk and shear modulus. Conversely, an initially floppy VM\nunder dilation can rigidify and have a higher bulk and shear modulus. These\nobservations imply that re-scaling of cell area shifts the transition between\nrigid and floppy states. Based on this insight, we calculate the re-scaling of\ncell area engendered by intrinsic curvature and write a prediction for the\nrigidity transition in the presence of curvature. The shift of the rigidity\ntransition in the presence of curvature for the VM provides a new metric for\npredicting tissue rigidity from image data for curved tissues in a manner\nanalogous to the flat case.",
        "positive": "Linear response to leadership, effective temperature and decision making\n  in flocks: Large collections of autonomously moving agents, such as animals or\nmicro-organisms, are able to 'flock' coherently in space even in the absence of\na central control mechanism. While the direction of the flock resulting from\nthis critical behavior is random, this can be controlled by a small subset of\ninformed individuals acting as leaders of the group. In this article we use the\nVicsek model to investigate how flocks respond to leadership and make\ndecisions. Using a combination of numerical simulations and continuous modeling\nwe demonstrate that flocks display a linear response to leadership that can be\ncast in the framework of the fluctuation-dissipation theorem, identifying an\n'effective temperature' reflecting how promptly the flock reacts to the\ninitiative of the leaders. The linear response to leadership also holds in the\npresence of two groups of informed individuals with competing interests,\nindicating that the flock's behavioral decision is determined by both the\nnumber of leaders and their degree of influence."
    },
    {
        "anchor": "The mechanism for the exceptionally high tear strength of carbon\n  black/Hevea natural rubber vulcanizates: Natural rubber vucanizates containing 0-50 phr of a fine carbon black\n(N115,d=27nm) were prepared and tensile strengths of normal (no pre-cut) and\nedge pre-cut specimens were determined. Normal tensile strengths of all\nvulcanizates were similar. At the relatively slow strain rate experienced\nwholesale by normal uncut specimens, all vulcanizates, prior to crack\ninitiation, strain-crystallized sufficiently to be strong. However, pre-cut\nspecimens experience increased strain rate at a cut tip. Magnification of the\nstrain rate increases as cut depth c increases. Fracture in the gum NR and\nvulcanizates with up to 14 phr of black occurred by simple forward crack growth\nfrom a cut tip, and all exhibited a critical cut size, above which strength\ndropped abruptly. Furthermore, for these lightly filled samples, strength and\ncritical cut size decreased with increased black content. This indicates less\nstrain-crystalliation before rupture of pre-cut specimens, when levels of black\nare low. This effect is attributerd to rapid straining at a cut tip and\nhindering of the chain mobility necessary for crystallization. When black\ncontent was increased to 15 phr, with 1 mm<c<2 mm, about 50% of specimens\nretained simple lateral fracture and were weak, but the other 50% developed\ndeviated cracks (knotty tearing) and were significantly stronger than\ncorresponding pre-cut gum specimens, especially at large c. High strength with\nsufficient black levels are attributed to increased strain-crystallization and\nsuper-blunting (multiple cracks) at a cut tip. These inhibit forward crack\ngrowth. For carbon black to enhance strain-crystallization relative to the gum,\nit appears there must be enough of it to form a bound rubber/black network. If\nthe black concentration is less than this percolation threshold,\nstrain-crystallization is hindered at a cut tip.",
        "positive": "Globular Structures of a Helix-Coil Copolymer: Self-Consistent Treatment: A self-consistent field theory was developed in the grand-canonical ensemble\nformulation to study transitions in a helix-coil multiblock globule. Helical\nand coil parts are treated as stiff rods and self-avoiding walks of variable\nlengths correspondingly. The resulting field-theory takes, in addition to the\nconventional Zimm-Bragg (B.H. Zimm, I.K. Bragg, J. Chem. Phys. 31, 526 (1959))\nparameters, also three-dimensional interaction terms into account. The\nappropriate differential equations which determine the self-consistent fields\nwere solved numerically with finite element method. Three different phase\nstates are found: open chain, amorphous globule and nematic liquid-crystalline\n(LC) globule. The LC-globule formation is driven by the interplay between the\nhydrophobic helical segments attraction and the anisotropic globule surface\nenergy of an entropic nature. The full phase diagram of the helix-coil\ncopolymer was calculated and thoroughly discussed. The suggested theory shows a\nclear interplay between secondary and tertiary structures in globular\nhomopolypeptides."
    },
    {
        "anchor": "Flow induced rigidity percolation in shear thickening suspensions: Discontinuous shear thickening (DST) is associated with a sharp rise of a\nsuspension's viscosity with increasing applied shear rate. A key signature of\nDST, highlighted in recent studies, is the very large fluctuations of the\nmeasured stress as the suspension thickens. A clear link between\nmicrostructural development and the dramatic increase of the stress\nfluctuations has not been established yet. To identify the microstructural\nunderpinnings of this behavior, we perform simulations of sheared dense\nsuspensions. By analyzing particle contact networks, we identify a subset of\nconstrained particles that contribute directly to the rapid rise in viscosity\nand the large stress fluctuations. Indeed, both phenomena can be explained by\nthe growth and percolation of constrained particle networks -- in direct\nanalogy to rigidity percolation. A finite size scaling analysis confirms this\nis a percolation phenomenon and allows us to estimate the critical exponents.\nOur findings reveal the specific microstructural transition that underlies DST.",
        "positive": "A statistical mechanical model of closed loop plectoneme supercoiling\n  and its variational approximation: Presented here, is a technical manuscript that may form the basis of later\npublished work. In it, we develop a statistical mechanical model to describe a\nclosed loop plectoneme, applicable for when the closed loop is sufficiently\nsupercoiled. The model divides the system up into end loops and a braided\nsection; the end loops are assumed to contribute little to the super-coil\nwrithe. Within the braided section, the model incorporates interactions that\ndepend on the structure of the molecule; in particular, we consider those that\ndepend on helical structure. A method for approximating the steric interactions\nis utilized that we had previously used in other publications. We go on to\nconstruct variational approximations for our closed loop plectoneme model in\ntwo cases. The first case is where helix dependent interactions are strong, and\nin the second case they are considered weak. In developing these\napproximations, we approximate the Fuller-White condition by replacing, in all\nexpressions that depend on twist, writhe with average writhe, valid when the\nbraided section is sufficiently long. How this approximation is made and the\nconditions when this approximation is valid are also discussed. The\napproximation allows for a Legendre transformation of the free energy, which\nwith the introduction of moment (or torque), effectively allowing for twist and\naverage writhe to be treated independently in the transformed (Gibbs like) free\nenergy. Next, we then show how one may compute the average writhe of the\nbraided section. Lastly, we discuss how some of the approximations considered\nmay be relaxed, and discuss how the resulting model free energy might be\ncomputed by MC simulation."
    },
    {
        "anchor": "From the stress response function (back) to the sandpile `dip': We relate the pressure `dip' observed at the bottom of a sandpile prepared by\nsuccessive avalanches to the stress profile obtained on sheared granular layers\nin response to a localized vertical overload. We show that, within a simple\nanisotropic elastic analysis, the skewness and the tilt of the response profile\ncaused by shearing provide a qualitative agreement with the sandpile dip\neffect. We conclude that the texture anisotropy produced by the avalanches is\nin essence similar to that induced by a simple shearing -- albeit tilted by the\nangle of repose of the pile. This work also shows that this response function\ntechnique could be very well adapted to probe the texture of static granular\npacking.",
        "positive": "Phase diagram of mechanically stretched DNA: The salt effect: The cations, in form of salt, present in the solution containing DNA play a\ncrucial role in the opening of two strands of DNA. We use a simple non linear\nmodel and investigate the role of these cations on the mechanical unzipping of\nDNA. The Hamiltonian is modified to incoporate the solvent effect and the\ncations present in the solution. We calculate the melting temperature as well\nas the critical force that is required to unzip the DNA molecule as a function\nof salt concentration of the solution. The phase diagrams are found to be in\nclose agreement with the experimental phase diagrams."
    },
    {
        "anchor": "Nonlinear mechanics of colloidal gels: creep, fatigue and shear-induced\n  yielding: Colloidal gels are formed through the aggregation of attractive particles,\nwhose size ranges from 10~nm to a few micrometers, suspended in a liquid. Such\ngels are ubiquitous in everyday life applications, from food products to paints\nor construction materials, in particular thanks to their ability to easily\n\"yield\", i.e., to turn from a solid to a liquid under the application of a weak\nexternal load. Understanding and controlling the mechanical response of\ncolloidal gels is therefore of prime importance. Depending on the details of\nthe system, however, the resulting gel networks present different\nmicrostructural organisations that may lead to widely different mechanical\nresponses. This raises important challenges in fully characterizing yielding\nand in uncovering the mechanisms of nonlinear response in colloidal gels. In\nthis paper, we distinguish between two classes of colloidal gels showing\nrespectively reversible yielding, where the gel network reforms upon load\nrelease, and irreversible yielding, where the network is fully destroyed\nthrough fractures and phase separation. This broad, empirical distinction is\nachieved through rheology and local experiments at a mesoscopic scale,\nintermediate between the network characteristic size and the sample size. We\nfurther discuss how the observables derived from creep and fatigue experiments\nmay be modelled to predict yielding and highlight open questions and future\nresearch directions in the domain.",
        "positive": "A stroll in the energy landscape: We review recent results on the potential energy landscape (PES) of model\nliquids. The role of saddle-points in the PES in connecting dynamics to statics\nis investigated, confirming that a change between minima-dominated and\nsaddle-dominated regions of the PES explored in equilibrium happens around the\nMode Coupling Temperature. The structure of the low-energy saddles in the\nbasins is found to be simple and hierarchically organized; the presence of\nsaddles nearby in energy to the local minima indicates that, at non-cryogenic\ntemperatures, entropic bottlenecks limit the dynamics."
    },
    {
        "anchor": "Topological and geometrical quantities in active cellular structures: Topological and geometrical properties and the associated topological defects\nfind a rapidly growing interest in studying the interplay between mechanics and\nthe collective behavior of cells on the tissue level. We here test if well\nstudied equilibrium laws for polydisperse passive systems such as the Lewis's\nand the Aboav-Weaire's law are applicable also for active cellular structures.\nLarge scale simulations, which are based on a multi phase field active polar\ngel model, indicate that these active cellular structures follow these laws. If\nthe system is in a state of collective motion also quantitative agreement with\ntypical values for passive systems is observed. If this state has not developed\nquantitative differences can be found. We further compare the model with\ndiscrete modeling approaches for cellular structures and show that essential\nproperties, such as T1 transitions and rosettes are naturally fulfilled.",
        "positive": "Collapse and coexistence for a molecular braid with an attractive\n  interaction component subject to mechanical forces: Dual mechanical braiding experiments provide a useful tool with which\ninvestigate the nature of interactions between rod-like molecules, for instance\nactin and DNA. In conditions close to molecular condensation, one would expect\nan appearance of a local minimum in the interaction potential between the two\nmolecules. We investigate this situation, introducing an attractive component\ninto the interaction potential, using a model developed for describing such\nexperiments. We consider attraction that does not depend on molecular\nstructure, as well that which depends on a DNA-like helix structure. In\nbraiding experiments, an attractive term may lead to certain effects. A local\nminimum may cause molecules to collapse from a loosely braided configuration\ninto a tight one, occurring at a critical value of the moment applied about the\naxis of the braid. For a fixed number of braid pitches, this may lead to\ncoexistence between the two braiding states, tight and loose. Coexistence\nimplies certain proportions of the braid are in each state, their relative size\ndepending on the number of braid pitches. This manifests itself as linear\ndependence in numerically calculated quantities as functions of the number of\nbraid pitches. Also, in the collapsed state, the braid radius stays roughly\nconstant. Furthermore, if the attractive interaction is helix dependent, the\nleft-right handed braid symmetry is broken. For a DNA like charge distribution,\nusing the Kornyshev-Leikin interaction model, our results suggest that\nsignificant braid collapse and coexistence only occurs for left handed braids.\nRegardless of the interaction model, the study highlights the possible\nqualitative physics of braid collapse and coexistence; and the role helix\nspecific forces might play, if important. The model could be used to connect\nother microscopic theories of interaction with braiding experiments."
    },
    {
        "anchor": "Fragile Glasses Associated with a Dramatic Drop of Entropy under\n  Supercooling: We perform kinetic Monte Carlo simulations of a distinguishable-particle\nlattice model of structural glasses with random particle interactions. By\nvarying the interaction distribution and the average particle hopping energy\nbarrier, we obtain an extraordinarily wide range of kinetic fragility. A\nstretching exponent, characterizing structural relaxation, is found to decrease\nwith the kinetic fragility in agreement with experiments. The most fragile\nglasses are those exhibiting low hopping barriers and, more importantly,\ndramatic drops of entropies upon cooling toward the glass transition\ntemperatures. The entropy drops reduce possible kinetic pathways and lead to\ndramatic slowdowns in the dynamics. In addition, the kinetic fragility is shown\nto correlate with a thermodynamic fragility.",
        "positive": "Super-heterodyne light scattering on interacting colloidal suspensions:\n  theory and experiment: In soft matter structure couples to flow and vice versa. Complementary to\nstructural investigations, we here are interested in the determination of\nparticle velocities of charged colloidal suspensions of different structure\nunder flow. In a combined effort of theory and experiment we determine the\nFourier transform of the super-heterodyne field auto-correlation function\n(power spectrum) which in frequency space is found to be well separated from\nhomodyne contributions and low frequency noise. Under certain conditions the\npower spectrum is dominated by incoherently scattered light, originating from\nthe unavoidable size polydispersity of colloidal particles. A simple\napproximate form for the low-wavenumber self-intermediate scattering function\nis proposed, reminiscent to the case of non-interacting particles. We\nexperimentally scrutinize the range of applicability of these simplified\ncalculations on employing a parabolic electro-osmotic flow profile. Both for\nnon-interacting and strongly interacting fluid particle systems, the spectra\nare well described as diffusion-broadened velocity distributions comprising an\nosmotic flow-averaged superposition of Lorentzians at distinct locations. We\ndiscuss the performance and scope of this approach with particular focus on\nmoderately strong interactions and on multiphase flow. In addition, we point to\nsome remaining theoretical challenges in connection to the observed linear\nincrease of the effective diffusion constant and the integrated spectral power\nwith increasing electric field strength."
    },
    {
        "anchor": "Computational modelling of the collective stochastic motion of Kinesin\n  nano motors: We have developed a two dimensional stochastic molecular dynamics model for\nthe description of intra cellular collective motion of bio motors, in\nparticular Kinesins, on a microtubular track. The model is capable or\nreproducing the hand-over-hand mechanism of the directed motion along the\nmicrotubule. The model gives the average directed velocity and the current of\nKinesins along the microtubule. It is shown that beyond a certain density of\nKinesins, the average velocity and current undergo notable decrease which is\ndue to formation of traffic jams in the system.",
        "positive": "Transport Phenomena in Fluid Films with Curvature Elasticity: Cellular membranes are elastic lipid bilayers that contain a variety of\nproteins, including ion channels, receptors, and scaffolding proteins. These\nproteins are known to diffuse in the plane of the membrane and to influence the\nbending of the membrane. Experiments have shown that lipid flow in the plane of\nthe membrane is closely coupled with the diffusion of proteins. Thus, there is\na need for a comprehensive framework that accounts for the interplay between\nthese processes. Here, we present a theory for the coupled in-plane viscous\nflow of lipids, diffusion of transmembrane proteins, and elastic deformation of\nlipid bilayers. The proteins in the membrane are modeled such that they\ninfluence membrane bending by inducing a spontaneous curvature. We formulate\nthe free energy of the membrane with a Helfrich-like curvature elastic energy\ndensity function modified to account for the chemical potential energy of\nproteins. We derive the conservation laws and equations of motion for this\nsystem. Finally, we present results from dimensional analysis and numerical\nsimulations and demonstrate the effect of coupled transport processes in\ngoverning the dynamics of membrane bending and protein diffusion."
    },
    {
        "anchor": "The Influence of Compressibility on the Restitution Coefficient for\n  Viscoelastic Spheres in Low-Velocity Normal Impacts: The influence of compressibility on the coefficient of restitution in the\nnormal impact of a rigid sphere onto a linear-viscoelastic compressible\nstandard solid under quasi-static conditions is studied using a numerical\nsolution procedure for the contact-impact problem based on the Method of\nDimensionality Reduction. We find that the influence of compressible material\nbehavior is most significant in parameter combinations with high energy\ndissipation in the bulk material during the impact. Thereby the restitution\ncoefficient is usually underestimated, if the material is assumed to be\nincompressible. This misestimating can be very significant (relative errors of\n100% and more are possible), even, if the actual Poisson ratio is very close to\n0.5.",
        "positive": "Discrete Elements Method: A New Kind of Initial Conditions - Tetrahedral\n  Packing of Balls: The Paper discusses the use of the regular packing of identical balls with\nthe coordination number 4 as a model of a medium consisting of fluid and solid\nparticles in the conditions of fluidization. It is proposed to use the examined\npacking of balls as an initial condition for the calculations by the Discrete\nElements Method (DEM) in technological processes in the fluidized bed in\nindustry, as well as in the modeling of processes that occur in hydraulic and\npneumatic transport of granular materials. Filtration properties of such\npacking required for its use as an initial condition in calculations by DEM are\nestimated."
    },
    {
        "anchor": "Effect of Chemical Structure on the Isobaric and Isochoric Fragility in\n  Polychlorinated Biphenyls: Pressure-volume-temperature data, along with dielectric relaxation\nmeasurements, are reported for a series of polychlorinated biphenyls (PCB),\ndiffering in the number of chlorine atoms on their phenyl rings. Analysis of\nthe results reveals that with increasing chlorine content, the relaxation times\nof the PCB become governed to a greater degree by density, rho, relative to the\neffect of temperature, T. This result is consistent with the respective\nmagnitudes of the scaling exponent, gamma, yielding superpositioning of the\nrelaxation times measured at various temperatures and pressures, when plotted\nversus rho^gamma/T. While at constant (atmospheric) pressure, fragilities for\nthe various PCB are equivalent, the fragility at constant volume varies\ninversely with chlorine content. Evidently, the presence of bulkier chlorine\natoms on the phenyl rings magnifies the effect density has on the relaxation\ndynamics.",
        "positive": "Temperature effects on drift of suspended single-domain particles\n  induced by the Magnus force: We study the temperature dependence of the drift velocity of single-domain\nferromagnetic particles induced by the Magnus force in a dilute suspension. A\nset of stochastic equations describing the translational and rotational\ndynamics of particles is derived, and the particle drift velocity that depends\non components of the average particle magnetization is introduced. The\nFokker-Planck equation for the probability density of magnetization\norientations is solved analytically in the limit of strong thermal fluctuations\nfor both the planar rotor and general models. Using these solutions, we\ncalculate the drift velocity and show that the out-of-plane fluctuations of\nmagnetization, which are not accounted for in the planar rotor model, play an\nimportant role. In the general case of arbitrary fluctuations, we investigate\nthe temperature dependence of the drift velocity by numerically simulating a\nset of effective stochastic differential equations for the magnetization\ndynamics."
    },
    {
        "anchor": "A geometry-originated universal relation for arbitrary convex hard\n  particles: We have discovered that two significant quantities within hard particle\nsystems: the probability of successfully inserting an additional particle at\nrandom and the scale distribution function, can be connected by a concise\nrelation. We anticipate that this relation holds universal applicability for\nconvex hard particles. Our investigations encompassed a range of particle\nshapes, including one-dimensional line segments, two-dimensional disks,\nequilateral and non-equilateral triangles, squares, rectangles, and\nthree-dimensional spheres. Remarkably, we have observed a close alignment\nbetween the two sides of the relation in all cases we examined. Furthermore, we\nshow that this relation can be derived from the fundamental thermodynamic\nrelation that connects entropy, pressure, and chemical potential. Our study\nunveils a geometrically rooted relation that underpins essential thermodynamic\nrelations, shedding light on the intricate interplay of geometry and\nthermodynamics in hard particle systems.",
        "positive": "Analytical Rescaling of Polymer Dynamics from Mesoscale Simulations: We present a theoretical approach to scale the artificially fast dynamics of\nsimulated coarse-grained polymer liquids down to its realistic value. As\ncoarse-graining affects entropy and dissipation, two factors enter the\nrescaling: inclusion of intramolecular vibrational degrees of freedom, and\nrescaling of the friction coefficient. Because our approach is analytical, it\nis general and transferable. Translational and rotational diffusion of\nunentangled and entangled polyethylene melts, predicted from mesoscale\nsimulations of coarse-grained polymer melts using our rescaling procedure, are\nin quantitative agreement with united atom simulations and with experiments."
    },
    {
        "anchor": "Towards the cellular-scale simulation of motor-driven cytoskeletal\n  assemblies: The cytoskeleton -- a collection of polymeric filaments, molecular motors,\nand crosslinkers -- is a foundational example of active matter, and in the cell\nassembles into organelles that guide basic biological functions. Simulation of\ncytoskeletal assemblies is an important tool for modeling cellular processes\nand understanding their surprising material properties. Here we present aLENS,\na novel computational framework to surmount the limits of conventional\nsimulation methods. We model molecular motors with crosslinking kinetics that\nadhere to a thermodynamic energy landscape, and integrate the system dynamics\nwhile efficiently and stably enforcing hard-body repulsion between filaments --\nmolecular potentials are entirely avoided in imposing steric constraints.\nUtilizing parallel computing, we simulate different mixtures of tens to\nhundreds of thousands of cytoskeletal filaments and crosslinking motors,\nrecapitulating self-emergent phenomena such as bundle formation and buckling,\nand elucidating how motor type, thermal fluctuations, internal stresses, and\nconfinement determine the evolution of active matter aggregates.",
        "positive": "How ions in solution can change the sign of the critical Casimir\n  potential: We show that hydrophilic ions present in a confined, near-critical aqueous\nmixture can lead to an attraction between like charge surfaces with opposing\npreferential adsorption of the two species of the mixture, even though the\ncorresponding Casimir potential in uncharged systems is repulsive. This\nprediction agrees with recent experiment [Nellen {\\it{et al.}}, Soft\nMatter{\\bf{80}}, 061143 (2011)]. We also show that oppositely charged\nhydrophobic surfaces can repel each other, although the Casimir potential\nbetween uncharged surfaces with like preferential adsorption (selectivity) is\nattractive. This behavior is expected when the electrostatic screening length\nis larger than the correlation length, and one of the confining surfaces is\nstrongly selective and weakly charged, whereas the other confining surface is\nweakly selective and strongly charged. The Casimir potential can change sign\nbecause the hydrophilic ions near the weakly hydrophobic surface can\novercompensate the effect of hydrophobicity, and this surface can act as a\nhydrophilic one. We also predict a more attractive interaction between\nhydrophilic surfaces and a more repulsive interaction between hydrophobic\nsurfaces than given by the sum of the Casimir and Deby-H\\\"uckel potentials. Our\ntheory is derived systematically from a microscopic approach, and combines the\nLandau-type and Debye-H\\\"uckel theories with an additional contribution of an\nentropic origin."
    },
    {
        "anchor": "Coupling between structural relaxation and diffusion in glass-forming\n  liquids under pressure variation: We theoretically investigate structural relaxation and activated diffusion of\nglass-forming liquids at different pressures using both the Elastically\nCollective Nonlinear Langevin Equation (ECNLE) theory and molecular dynamics\n(MD) simulation. An external pressure restricts local motions of a single\nmolecule within its cage and triggers the slowing down of cooperative mobility.\nWhile the ECNLE theory and simulation generally predict a monotonic increase of\nthe glass transition temperature and dynamic fragility with pressure, the\nsimulation indicates a decrease of fragility as pressure above 1000 bar. The\nstructural relaxation time is found to be linearly coupled with the inverse\ndiffusion constant. Remarkably, this coupling is independent of compression.\nTheoretical calculations agree quantitatively well with simulations and are\nalso consistent with prior works.",
        "positive": "Transport of Brownian particles in a narrow, slowly-varying serpentine\n  channel: We study the transport of Brownian particles under a constant driving force\nand moving in channels that present a varying centerline but have constant\naperture width. We investigate two types of channels, {\\it solid} channels in\nwhich the particles are geometrically confined between walls and {\\em soft}\nchannels in which the particles are confined by a periodic potential. We\nconsider the limit of narrow, slowly-varying channels, i.e., when the aperture\nand the variation in the position of the centerline are small compared to the\nlength of a unit cell in the channel (wavelength). We use the method of\nasymptotic expansions to determine both the average velocity (or mobility) and\nthe effective diffusion coefficient of the particles. We show that both solid\nand soft-channels have the same effects on the transport properties up to\n$O(\\epsilon^2)$. We also show that the mobility in a solid-channel at\n$O(\\epsilon^4)$ is smaller than that in a soft-channel. Interestingly, in both\ncases, the corrections to the mobility of the particles are independent of the\nP\\'eclet number and, as a result, the Einstein-Smoluchowski relation is\nsatisfied. Finally, we show that by increasing the solid-channel width from\n$w(x)$ to $\\sqrt{6/\\pi}w(x)$, the mobility of the particles in the\nsolid-channel can be matched to that in the soft-channel up to $O(\\epsilon^4)$."
    },
    {
        "anchor": "Irregular Motion of a Falling Spherical Object Through Non-Newtonian\n  Fluid: The falling of an object through a non-Newtonian fluid is an interesting\nproblem, depending on the details of the rheology of the fluid. In this paper\nwe report on the settling of spherical objects through two non-Newtonian\nfluids: Laponite and hair Gel. A falling object's behavior in passing through a\nthixotropic colloidal suspension of synthetic clay, Laponite, has been reported\nto have many behavioral regimes. Here we report observation of a new regime\nwhere irregular motion is observed. We argue that this irregular motion may be\ninterpreted as onset of chaos. Observation of this regime depends on the size\nof the falling sphere, relaxation time of fluid and concentration of particles\nin the suspension. Similar experiments in Gel, a yield stress polymeric fluid,\ndo not reveal such behavior.",
        "positive": "Monte Carlo simulation of electrostatic interactions in inhomogeneous\n  dielectric media: Correct sampling for the local lattice simulation algorithm: We present a lattice Monte Carlo algorithm based on the one originally\nproposed by Maggs and Rossetto for simulating electrostatic interactions in\ninhomogeneous dielectric media. The original algorithm is known to produce\nattractive interactions between particles of the same dielectric constant in\nthe medium of different dielectric constant. We demonstrate that such\ninteractions are spurious, caused by incorrectly biased statistical weight\narising from particle motion during the Monte Carlo moves. We propose a simple\nparallel tempering algorithm that corrects this unphysical bias. The efficacy\nof our algorithm is tested on a simple binary mixture and on an uncharged\npolymer in a solvent, and applied to salt-doped polymer solutions."
    },
    {
        "anchor": "The Phase Synchronized State of Oriented Active Fluids: We present a theory for self-driven fluids, such as motorized cytoskeletal\nextracts or bacterial suspensions, that takes into account the underlying\nperiodic duty cycle carried by the active particles of which the system is\ncomposed. We show that the fluid can enter a state in which the constituent\nelements synchronize their phases. This spontaneous breaking of\ntime-translation invariance gives rise to flow instabilities distinct from\nthose arising in phase-incoherent active matter.",
        "positive": "Electrohydrodynamic Quincke rotation of a prolate ellipsoid: We experimentally study the occurrence of spontaneous spinning (Quincke\nrotation) of an ellipsoid in a uniform DC electric field. For an ellipsoid\nsuspended in an unbounded fluid, we find two stable states characterized by the\norientation of the ellipsoid long axis relative to the applied electric field :\nspinless (parallel) and spinning (perpendicular). The phase diagram of\nellipsoid behavior as a function of field strength and aspect ratio is in close\nagreement with the theory of Cebers et al. Phys. Rev .E 63:016301 (2000). We\nalso investigated the dynamics of the ellipsoidal Quincke rotor resting on a\nplanar surface with normal perpendicular to the field direction. We find novel\nbehaviors, such as swinging (long axis oscillating around the applied field\ndirection) and tumbling, due to the confinement."
    },
    {
        "anchor": "Large Force Fluctuations in a Flowing Granular Medium: We report the characteristics of the temporal fluctuations in the local force\ndelivered to the wall of a 2D hopper by a granular medium flowing through it.\nThe forces are predominantly impulsive at all flow rates for which the flow\ndoes not permanently jam. The average impulse delivered to the wall is much\nlarger than the momentum acquired by a single particle under gravity between\ncollisions, reflecting the fact that momentum is transferred to the walls from\nthe bulk of the flow by collisions. At values larger than the average impulse,\nthe probability distribution of impulses is broad and decays exponentially on\nthe scale of the average impulse, just as it does in static granular media. At\nsmall impulse values, the probability distribution evolves continuously with\nflow velocity but does not show a clear signature of the transition from purely\ncollisional flow to intermittently jamming flows. However, the time interval\nbetween collisions tends to a power law distribution, $P(\\tau)\\sim\n\\tau^{-3/2}$, thus showing a clear dynamical signature of the approach to\njamming.",
        "positive": "Origin of Anomalous Diffusion and Non-Gaussian Effects for Hard Spheres:\n  Analysis of Three-Time Correlations: We present new simulation results on a hard sphere system at high densities.\nUsing three-time correlations, we can account for the anomalous diffusion,\nwhich results from a homogeneous back-dragging effect. Furthermore, we\ncalculate the non-gaussian parameter and connect it to the existence of dynamic\nheterogeneities."
    },
    {
        "anchor": "Microscopic theory of a Janus motor in a non-equilibrium fluid: Surface\n  hydrodynamics and boundary conditions: We present a derivation from first principles of the coupled equations of\nmotion of an active self-diffusiophoretic Janus motor and the hydrodynamic\ndensities of its fluid environment that are nonlinearly displaced from\nequilibrium. The derivation makes use of time-dependent projection operator\ntechniques defined in terms of slowly varying coarse-grained microscopic\ndensities of the fluid species number, total momentum, and energy. The exact\nequations of motion are simplified using time-scale arguments, resulting in\nMarkovian equations for the Janus motor linear and angular velocities with\naverage forces and torques that depend on the fluid densities. For a large\ncolloid, the fluid equations are separated into bulk and interfacial\ncontributions, and the conditions under which the dynamics of the fluid\ndensities can be accurately represented by bulk hydrodynamic equations subject\nto boundary conditions on the colloid are determined. We show how the results\nfor boundary conditions based on continuum theory can be obtained from the\nmolecular description and provide Green-Kubo expressions for all transport\ncoefficients, including the diffusiophoretic coupling and the slip coefficient.",
        "positive": "Simulations of Coulomb systems confined by polarizable surfaces using\n  periodic Green functions: We present an efficient approach for simulating Coulomb systems confined by\nplanar polarizable surfaces. The method is based on the solution of Poisson\nequation using periodic Green functions. It is shown that the electrostatic\nenergy arising from surface polarization can be decoupled from the energy of\nperiodic replicas. This allows us to combine an efficient Ewald summation\nmethod for the replicas with the polarization contribution calculated using\nGreen function techniques. We apply the method to calculate density profiles of\nions confined between charged dielectric and metal interfaces."
    },
    {
        "anchor": "A swollen phase observed between the liquid-crystalline phase and the\n  interdigitated phase induced by pressure and/or adding ethanol in DPPC\n  aqueous solution: A swollen phase, in which the mean repeat distance of lipid bilayers is\nlarger than the other phases, is found between the liquid-crystalline phase and\nthe interdigitated gel phase in DPPC aqueous solution. Temperature, pressure\nand ethanol concentration dependences of the structure were investigated by\nsmall-angle neutron scattering, and a bending rigidity of lipid bilayers was by\nneutron spin echo. The nature of the swollen phase is similar to the anomalous\nswelling reported previously. However, the temperature dependence of the mean\nrepeat distance and the bending rigidity of lipid bilayers are different. This\nphase could be a precursor to the interdigitated gel phase induced by pressure\nand/or adding ethanol.",
        "positive": "Dynamical scaling of the DNA unzipping transition: We report studies of the equilibrium and the dynamics of a general set of\nlattice models which capture the essence of the force-induced or mechanical DNA\nunzipping transition. Besides yielding the whole equilibrium phase diagram in\nthe force vs temperature plane, which reveals the presence of an interesting\nre-entrant unzipping transition for low T, these models enable us to\ncharacterize the dynamics of the process starting from a non-equilibrium\ninitial condition. The thermal melting of the DNA strands displays a model\ndependent time evolution. On the contrary, our results suggest that the\ndynamical mechanism for the unzipping by force is very robust and the scaling\nbehaviour does not depend on the details of the description we adopt."
    },
    {
        "anchor": "Adsorption vs. folding of a Hydrophobic Chain Protein Model near an\n  Attractive Surface: The folding vs. adsorption behaviour of a coarse-grained off-lattice protein\nmodel near an attractive surface is presented within the frame of a\nMulticanonical Monte Carlo simulations. In the polymer-surface model, the\nLennard-Jones potential is assumed as an interaction potential between the\neffective monomers and the attractive surface. Thermodynamic properties and\nsome structural parameters for the minimum energy conformations are calculated\nfor comparison of the folding and adsorption cases.",
        "positive": "Structural properties of hard-disk fluids under single-file confinement: The structural properties of confined single-file hard-disk fluids are\nstudied analytically by means of a mapping of the original system onto a\none-dimensional mixture of non-additive hard rods, the mapping being exact in\nthe polydisperse limit. Standard statistical-mechanical results are used as a\nstarting point to derive thermodynamic and structural properties of the\none-dimensional mixture, where the condition that all particles have the same\nchemical potential must be taken into account. Analytical results are then\nprovided for the $n$th neighbor probability distribution function, the radial\ndistribution function, and the structure factor, a very good agreement being\nobserved upon comparison with simulation data from the literature. Moreover, we\nhave analyzed the scaling form for the disappearance of defects in the zigzag\nconfiguration for high pressure, and have obtained the translational\ncorrelation length and the structural crossover in the oscillation frequency\nfor asymptotically large distances."
    },
    {
        "anchor": "Apparent Contact Angle and Contact Angle Hysteresis on Liquid Infused\n  Surfaces: We theoretically investigate the apparent contact angle and contact angle\nhysteresis of a droplet placed on a liquid infused surface. We show that the\napparent contact angle is not uniquely defined by material parameters, but also\nhas a strong dependence on the relative size between the droplet and its\nsurrounding wetting ridge formed by the infusing liquid. We derive a closed\nform expression for the contact angle in the limit of vanishing wetting ridge,\nand compute the correction for small but finite ridge, which corresponds to an\neffective line tension term. We also predict contact angle hysteresis on liquid\ninfused surfaces generated by the pinning of the contact lines by the surface\ncorrugations. Our analytical expressions for both the apparent contact angle\nand contact angle hysteresis can be interpreted as `weighted sums' between the\ncontact angles of the infusing liquid relative to the droplet and surrounding\ngas phases, where the weighting coefficients are given by ratios of the fluid\nsurface tensions.",
        "positive": "Double diffusivity model under stochastic forcing: The \"double diffusivity\" model was proposed in the late 1970s, and reworked\nin the early 1980s, as a continuum counterpart to existing discrete models of\ndiffusion corresponding to high diffusivity paths, such as grain boundaries and\ndislocation lines. Technically, the model pans out as a system of coupled {\\it\nFick type} diffusion equations to represent \"regular\" and \"high\" diffusivity\npaths with \"source terms\" accounting for the mass exchange between the two\npaths. The model remit was extended by analogy to describe flow in porous media\nwith double porosity, as well as to model heat conduction in media with two\nnon-equilibrium local temperature baths e.g. ion and electron baths. Uncoupling\nof the two partial differential equations leads to a higher-ordered diffusion\nequation, solutions of which could be obtained in terms of classical diffusion\nequation solutions. Similar equations could also be derived within an \"internal\nlength\" gradient (ILG) mechanics formulation applied to diffusion problems,\n{\\it i.e.}, by introducing nonlocal effects, together with inertia and\nviscosity, in a mechanics based formulation of diffusion theory. This issue\nbecomes particularly important in the case of diffusion in nanopolycrystals\nwhose deterministic ILG based theoretical calculations predict a relaxation\ntime that is only about one-tenth of the actual experimentally verified\ntimescale. This article provides the \"missing link\" in this estimation by\nadding a vital element in the ILG structure, that of stochasticity, that takes\ninto account all boundary layer fluctuations. Our stochastic-ILG diffusion\ncalculation confirms rapprochement between theory and experiment, thereby\nbenchmarking a new generation of gradient-based continuum models that conform\ncloser to real life fluctuating environments."
    },
    {
        "anchor": "Solid like friction of a polymer chain: We propose a simple friction model for isolated polymer chains on a solid\nsubstrate. The chains are pulled at constant velocity by one end, the other end\ncan be trapped on the solid substrate on localised sites. We focus on the\nenergy dissipation due to the traps. This simple model leads to non trivial\nfriction laws, depending on the velocity and the distance between traps. Some\nrefinements of the model such as the effect of thermal fluctuation are also\nreported.",
        "positive": "Primitive Model Electrolytes in the Near and Far Field: Decay Lengths\n  from DFT and Simulations: Inspired by recent experimental observations of anomalously large decay\nlengths in concentrated electrolytes, we revisit the Restricted Primitive Model\n(RPM) for an aqueous electrolyte. We investigate the asymptotic decay lengths\nof the one-body ionic density profiles for the RPM in contact with a planar\nelectrode using classical Density Functional Theory (DFT), and compare these\nwith the decay lengths of the corresponding two-body correlation functions in\nbulk systems, obtained in previous Integral Equation Theory (IET) studies.\nExtensive Molecular Dynamics (MD) simulations are employed to complement the\nDFT and IET predictions. Our DFT calculations incorporate electrostatic\ninteractions between the ions using three different (existing) approaches: one\nbased on the simplest mean field treatment of Coulomb interactions (MFC),\nwhilst the other two employ the Mean Spherical approximation (MSA). The MSAc\ninvokes only the MSA bulk direct correlation function whereas the MSAu also\nincorporates the MSA bulk internal energy. Although MSAu yields profiles that\nagree best with MD simulations in the near field, in the far field we observe\nthat the decay lengths are consistent between IET, MSAc, and MD simulations,\nwhereas those from MFC and MSAu deviate significantly. Using DFT we calculated\nthe solvation force, which relates directly to surface force experiments. We\nfind that its decay length is neither qualitatively nor quantitatively close to\nthe large decay lengths measured in experiments and conclude that the latter\ncannot be accounted for by the primitive model. The anomalously large decay\nlengths found in surface force measurements require an explanation that lies\nbeyond primitive models."
    },
    {
        "anchor": "Autosolitons in trapped Bose-Einstein condensates with two- and\n  three-body inelastic processes: In this work, we consider the conditions for the existence of autosolitons,\nin trapped Bose-Einstein condensates with attractive atomic interactions.\nFirst, the variational approach is employed to estimate the stationary\nsolutions for the three-dimensional Gross-Pitaevskii equation with trap\npotential, linear atomic feeding from the thermal cloud and two- and three-body\ninelastic processes. Next, by using exact numerical calculations, we show that\nthe variational approach gives reliable analytical results. We also discuss the\npossible observation of autosolitons in experiments with Lithium-7.",
        "positive": "Meshfree elastoplastic solid for nonsmooth multidomain dynamics: A method for simulation of elastoplastic solids in multibody systems with\nnonsmooth and multidomain dynamics is developed. The solid is discretised into\npseudo-particles using the meshfree moving least squares method. The particles\ncarry strain and stress tensor variables that are mapped to deformation\nconstraints and constraint forces. The discretised solid model thus fit a\nunified framework for nonsmooth multidomain dynamics for realtime simulations\nincluding strong coupling of rigid multibodies with complex kinematic\nconstraints such as articulation joints, unilateral contacts with dry friction,\ndrivelines and hydraulics. The nonsmooth formulation allow for impulses, due to\nimpacts for instance, to propagate instantly between the rigid multibody and\nthe solid. Plasticity is introduced through an associative perfectly plastic\nmodified Drucker-Prager model. The elastic and plastic dynamics is verified for\nsimple test systems and the capability of simulating tracked terrain vehicles\ndriving on a deformable terrain is demonstrated."
    },
    {
        "anchor": "Size-dependent same-material tribocharging in insulating grains: Observations of flowing granular matter have suggested that same-material\ntribocharging de- pends on particle size, rendering large grains positive and\nsmall ones negative. Models assuming the transfer of trapped electrons can\nexplain this, but so far have not been validated. Tracking individual grains in\nan electric field, we show quantitatively that charge is transferred based on\nsize between materially identical grains. However, the surface density of\ntrapped electrons, measured independently by thermoluminescence techniques, is\norders of magnitude too small to account for the scale of charge transferred.\nThis suggests that another negatively charged species, such as ions, is\nresponsible.",
        "positive": "On the stupendous beauty of closure: Closure seems to be something rheologists would prefer to avoid. Here, the\nstory of closure is told in such a way that one should enduringly forget any\nimproper undertone of \"uncontrolled approximation\" or \"necessary evil\" which\nmight arise, for example, in reducing a diffusion equation in configuration\nspace to moment equations. In its widest sense, closure is associated with the\nsearch for self-contained levels of description on which time-evolution\nequations can be formulated in a closed, or autonomous, form. Proper closure\nrequires the identification of the relevant structural variables participating\nin the dominant processes in a system of interest, and closure hence is\nsynonymous with focusing on the essence of a problem and consequently with deep\nunderstanding. The derivation of closed equations may or may not be accompanied\nby the elimination of fast processes in favor of dissipation. As a general\nrequirement, any closed set of evolution equations should be thermodynamically\nadmissible. Thermodynamic admissibility comprises much more than the second law\nof thermodynamics, most notably, a clear separation of reversible and\nirreversible effects and a profound geometric structure of the reversible terms\nas a hallmark of reversibility. We discuss some implications of the intimate\nrelationship between nonequilibrium thermodynamics and the principles of\nclosure for rheology, and we illustrate the abstract ideas for the rod model of\nliquid crystal polymers, bead-spring models of dilute polymer solutions, and\nthe reptation model of melts of entangled linear polymers."
    },
    {
        "anchor": "Tunable dynamic response of magnetic gels: impact of structural\n  properties and magnetic fields: Ferrogels and magnetic elastomers feature mechanical properties that can be\nreversibly tuned from outside through magnetic fields. Here we concentrate on\nthe question how their dynamic response can be adjusted. The influence of three\nfactors on the dynamic behavior is demonstrated using appropriate minimal\nmodels: first, the orientational memory imprinted into one class of the\nmaterials during their synthesis; second, the structural arrangement of the\nmagnetic particles in the materials; and third, the strength of an external\nmagnetic field. To illustrate the latter point, structural data are extracted\nfrom a real experimental sample and analyzed. Understanding how internal\nstructural properties and external influences impact the dominant dynamical\nproperties helps to design materials that optimize the requested behavior.",
        "positive": "Simulating active agents under confinement with Dissipative Particles\n  (hydro)Dynamics: We study active agents embedded in bulk or in confinement explicitly\nconsidering hydrodynamics and simulating the swimmers via an implementation\ninspired by the squirmer model. We develop a Dissipative Particle Dynamics\nscheme for the solvent. This approach allows us to properly deal not only with\nhydrodynamics but also with thermal fluctuations. On the other side, this\napproach enables us to study active agents with complex shapes, ranging from\nspherical colloids to polymers. To start with, we study a simple spherical\ncolloid. We analyze the features of the velocity fields of the surrounding\nsolvent, when the colloid is a pusher, a puller or a neutral swimmer either in\nbulk or confined in a cylindrical channel. Next, we characterise its dynamical\nbehaviour by computing the mean square displacement and the long time diffusion\nwhen the active colloid is in bulk or in a channel (varying its radius) and\nanalyze the orientation autocorrelation function in the latter case. While the\nthree studied squirmer types are characterised by the same bulk diffusion, the\ncylindrical confinement considerably modulates the diffusion and the\norientation autocorrelation function. Finally, we focus our attention on a more\ncomplex shape: an active polymer. We first characterise the structural features\ncomputing its radius of gyration when in bulk or in cylindrical confinement,\nand compare to known results obtained without hydrodynamics. Next, we\ncharacterise the dynamical behaviour of the active polymer by computing its\nmean square displacement and the long time diffusion. On the one hand, both\ndiffusion and radius of gyration decrease due to the hydrodynamic interaction\nwhen the system is in bulk. On the other hand, the effect of confinement is to\ndecrease the radius of gyration, disturbing the motion of the polymer and thus\nreducing its diffusion."
    },
    {
        "anchor": "2H and 13C NMR studies on the temperature-dependent water and protein\n  dynamics in hydrated elastin, myoglobin and collagen: 2H NMR spin-lattice relaxation and line-shape analyses are performed to study\nthe temperature-dependent dynamics of water in the hydration shells of\nmyoglobin, elastin, and collagen.",
        "positive": "Polar self-organization of ferroelectric nematic liquid crystal\n  molecules on atomically flat Au(111) surface: Understanding nanoscale mechanisms responsible for the recently discovered\nferroelectric nematics can be helped by direct visualization of self-assembly\nof strongly polar molecules. Here we report on scanning tunneling microscopy\n(STM) studies of monomolecular layers of a ferroelectric nematic liquid crystal\non a reconstructed Au(111) surface. The monolayers are obtained by deposition\nfrom a solution at ambient conditions. The adsorbed ferroelectric nematic\nmolecules self-assemble into regular rows with tilted orientation, resembling a\nlayered structure of a smectic C. Remarkably, each molecular dipole in this\narchitecture is oriented along the same direction giving rise to polar\nferroelectric ordering."
    },
    {
        "anchor": "Role of Multipoles in Counterion-Mediated Interactions between Charged\n  Surfaces: Strong and Weak Coupling: We present general arguments for the importance, or lack thereof, of the\nstructure in the charge distribution of counterions for counterion-mediated\ninteractions between bounding symmetrically charged surfaces. We show that on\nthe mean field or weak coupling level, the charge quadrupole contributes the\nlowest order modification to the contact value theorem and thus to the\nintersurface electrostatic interactions. The image effects are non-existent on\nthe mean-field level even with multipoles. On the strong coupling level the\nquadrupoles and higher order multipoles contribute additional terms to the\ninteraction free energy only in the presence of dielectric inhomogeneities.\nWithout them, the monopole is the only multipole that contributes to the strong\ncoupling electrostatics. We explore the consequences of these statements in all\ntheir generality.",
        "positive": "Dynamics and energetics of ion adsorption at the interface between a\n  pure ionic liquid and carbon electrodes: Molecular dynamics simulations have been used extensively to determine\nequilibrium properties of the electrode-electrolyte interface in\nsupercapacitors held at various potentials. While such studies are essential to\nunderstand and optimize the performance of such energy storage systems,\ninvestigations of the dynamics of adsorption during the charge of the\nsupercapacitors is also necessary. Dynamical properties are especially\nimportant to get an insight into the power density of supercapacitors, one of\ntheir main assets. In this work, we propose a new method to analyze the\ntrajectories of adsorbing ions. We focus on pure 1-ethyl-3-methylimidazolium\nbis(trifluoromethylsulfonyl)imide in contact with planar carbon electrodes. We\ncharacterize the evolution of the ion orientation and ion-electrode distance\nduring adsorption and show that ions reorientate as they adsorb. We then\ndetermine the forces experienced by the adsorbing ions and demonstrate that\nCoulomb forces dominate at long range while van der Waals forces dominate at\nshort range. We also show that there is an almost equal contribution from the\ntwo forces at an intermediate distance, explaining the peak of ion density\nclose to the electrode surface."
    },
    {
        "anchor": "The Liquid Blister Test: We consider a thin elastic sheet adhering to a stiff substrate by means of\nthe surface tension of a thin liquid layer. Debonding is initiated by imposing\na vertical displacement at the centre of the sheet and leads to the formation\nof a delaminated region, or `blister'. This experiment reveals that the\nperimeter of the blister takes one of three different forms depending on the\nvertical displacement imposed. As this displacement is increased, we observe\nfirst circular, then undulating and finally triangular blisters. We obtain\ntheoretical predictions for the observed features of each of these three\nfamilies of blisters. The theory is built upon the F\\\"{o}ppl-von K\\'{a}rm\\'{a}n\nequations for thin elastic plates and accounts for the surface energy of the\nliquid. We find good quantitative agreement between our theoretical predictions\nand experimental results, demonstrating that all three families are governed by\ndifferent balances between elastic and capillary forces. Our results may bear\non micrometric tapered devices and other systems where elastic and adhesive\nforces are in competition.",
        "positive": "Dynamics of type V menthol-thymol deep eutectic solvents: Do they reveal\n  non-ideality?: We have established a comprehensive study of the molecular dynamics of the\nmenthol-thymol mixture, the prototype of the new class of type V deep eutectic\nsolvents. Dielectric spectroscopy and differential scanning calorimetry were\ncombined to assess the dipolar relaxation and glassy dynamics over an extended\nrange of timescales (10-6-10 2 s) and for eleven different compositions\nincluding the two pure constituents. Positive deviations from ideal mixing\napproximation were demonstrated for both the solvent dielectric strength and\nthe glass transition. They support the idea that preferential H-bond\ninteractions between unlike molecules induce structural rearrangements in the\nDES mixtures. Excellent glassforming capability of the DES mixtures was\ndemonstrated for a broad range of compositions (xThymol = 0.4-0.7). In this\ncase, the dipolar dynamics could be assessed from the normal liquid to the\ndeeply supercooled state. Many salient parameters of the relaxation functions,\nincluding fragility, non-Debye character and rotation-translation decoupling\npoint to the development of dynamic heterogeneities."
    },
    {
        "anchor": "Unearthing the anticrystal: criticality in the linear response of\n  disordered solids: The fact that a disordered material is not constrained in its properties in\nthe same way as a crystal presents significant and yet largely untapped\npotential for novel material design. However, unlike their crystalline\ncounterparts, disordered solids are not well understood. One of the primary\nobstacles is the lack of a theoretical framework for thinking about disorder\nand its relation to mechanical properties. To this end, we study an idealized\nsystem of frictionless athermal soft spheres that, when compressed, undergoes a\njamming phase transition with diverging length scales and clean power-law\nsignatures. This critical point is the cornerstone of a much larger \"jamming\nscenario\" that has the potential to provide the essential theoretical\nfoundation necessary for a unified understanding of the mechanics of disordered\nsolids. We begin by showing that jammed sphere packings have a valid linear\nregime despite the presence of \"contact nonlinearities.\" We then investigate\nthe critical nature of the transition, focusing on diverging length scales and\nfinite-size effects. Next, we argue that jamming plays the same role for\ndisordered solids as the perfect crystal plays for crystalline solids. Not only\ncan it be considered an idealized starting point for understanding disordered\nmaterials, but it can even influence systems that have a relatively high amount\nof crystalline order. The behavior of solids can thus be thought of as existing\non a spectrum, with the perfect crystal and the jamming transition at opposing\nends. Finally, we introduce a new principle wherein the contribution of an\nindividual bond to one global property is independent of its contribution to\nanother. This principle allows the different global responses of a disordered\nsystem to be manipulated independently and provides a great deal of flexibility\nin designing materials with unique, textured and tunable properties.",
        "positive": "Guided waves in pre-stressed hyperelastic plates and tubes: Application\n  to the ultrasound elastography of thin-walled soft materials: In vivo measurement of the mechanical properties of thin-walled soft tissues\n(e.g., mitral valve, artery and bladder) and in situ mechanical\ncharacterization of thin-walled artificial soft biomaterials in service are of\ngreat challenge and difficult to address via commonly used testing methods.\nHere we investigate the properties of guided waves generated by focused\nacoustic radiation force in immersed pre-stressed plates and tubes, and show\nthat they can address this challenge. To this end, we carry out both (i) a\ntheoretical analysis based on incremental wave motion in finite deformation\ntheory and (ii) finite element simulations. Our analysis leads to a novel\nmethod based on the ultrasound elastography to image the elastic properties of\npre-stressed thin-walled soft tissues and artificial soft materials in a\nnon-destructive and non-invasive manner. To validate the theoretical and\nnumerical solutions and demonstrate the usefulness of the corresponding method\nin practical measurements, we perform (iii) experiments on polyvinyl alcohol\ncryogel phantoms immersed in water, using the Verasonics V1 System equipped\nwith a L10-5 transducer. Finally, potential clinical applications of the method\nhave been discussed."
    },
    {
        "anchor": "Critical Casimir forces in soft matter: We review recent advances in the theoretical, numerical, and experimental\nstudies of critical Casimir forces in soft matter, with particular emphasis on\ntheir relevance for the structures of colloidal suspensions and on their\ndynamics. Distinct from other interactions which act in soft matter, such as\nelectrostatic and van der Waals forces, critical Casimir forces are effective\ninteractions characterised by the possibility to control reversibly their\nstrength via minute temperature changes, while their attractive or repulsive\ncharacter is conveniently determined via surface treatments or by structuring\nthe involved surfaces. These features make critical Casimir forces excellent\ncandidates for controlling the equilibrium and dynamical properties of\nindividual colloids or colloidal dispersions as well as for possible\napplications in micro-mechanical systems. In the past 25 years a number of\ntheoretical and experimental studies have been devoted to investigate these\nforces primarily under thermal equilibrium conditions, while their dynamical\nand non-equilibrium behaviour is a largely unexplored subject open for future\ninvestigations.",
        "positive": "Structure and Diffusion of Nanoparticle Monolayers Floating at\n  Liquid/Vapor Interfaces: A Molecular Dynamics Study: Large-scale molecular dynamics simulations are used to simulate a layer of\nnanoparticles diffusing on the surface of a liquid. Both a low viscosity\nliquid, represented by Lennard-Jones monomers, and a high viscosity liquid,\nrepresented by linear homopolymers, are studied. The organization and diffusion\nof the nanoparticles are analyzed as the nanoparticle density and the contact\nangle between the nanoparticles and liquid are varied. When the interaction\nbetween the nanoparticles and liquid is reduced the contact angle increases and\nthe nanoparticles ride higher on the liquid surface, which enables them to\ndiffuse faster. In this case the short range order is also reduced as seen in\nthe pair correlation function. For the polymeric liquids, the out-of-layer\nfluctuation is suppressed and the short range order is slightly enhanced.\nHowever, the diffusion becomes much slower and the mean square displacement\neven shows sub-linear time dependence at large times. The relation between\ndiffusion coefficient and viscosity is found to deviate from that in bulk\ndiffusion. Results are compared to simulations of the identical nanoparticles\nin 2-dimensions."
    },
    {
        "anchor": "Irregularity of polymer domain boundaries in two-dimensional polymer\n  solution: Polymer chains composing a polymer solution in strict two dimensions (2D) are\ncharacterized with irregular domain boundaries, whose fractal dimension\n($\\mathcal{D}^{\\partial}$) varies with the area fraction of the solution and\nthe solvent quality. {\\color{black}Our analysis of numerical simulations of\npolymer solutions finds} that $\\mathcal{D}^{\\partial}$ in good solvents changes\nnon-monotonically from $\\mathcal{D}^{\\partial}=4/3$ in dilute phase to\n$\\mathcal{D}^{\\partial}=5/4$ in dense phase, maximizing to\n$\\mathcal{D}^{\\partial}\\approx 3/2$ at a crossover area fraction $\\phi_{\\rm\ncr}\\approx 0.2$, whereas for polymers in $\\Theta$ solvents\n$\\mathcal{D}^{\\partial}$ remains constant at $\\mathcal{D}^{\\partial}=4/3$ from\ndilute to semi-dilute phase. Using polymer physics arguments, we rationalize\nthese values, and show that the maximum irregularity of\n$\\mathcal{D}^\\partial\\approx 3/2$ is due to \"fjord\"-like corrugations formed\nalong the domain boundaries which also maximize at the same crossover area\nfraction. Our finding of $\\mathcal{D}^\\partial\\approx 3/2$ is, in fact, in\nperfect agreement with the upper bound for the fractal dimension of the\nexternal perimeter of 2D random curves at scaling limit, which is predicted by\nthe Schramm-Loewner evolution (SLE).",
        "positive": "Base pair dynamic assisted charge transport in DNA: An 1d model with time-dependent random hopping is proposed to describe charge\ntransport in DNA. It admits to investigate both diffusion of electrons and\ntheir tunneling between different sites in DNA. The tunneling appears to be\nstrongly temperature-dependent. Observations of a strong (exponential) as well\nas a weak distance dependence of the charge transfer in DNA can be explained in\nthe framework of our model."
    },
    {
        "anchor": "Early stages of spreading and sintering: The early stages of sintering of highly viscous droplets are very similar to\nthe early stages of a viscous droplet spreading on a solid substrate. The flows\nin both problems are closely analogous to the displacements in a Hertzian\nelastic contact. We exploit that analogy to provide both a scaling argument and\na calculation for the early growth of the contact radius $a$ with time, namely\n$a=(3 \\pi \\gamma R^2 t/(32 \\eta))^{1/3}$. (This result is complementary to the\nwell-known Tanner law for spreading, $a \\sim t^{1/10}$, which holds in the\nregime of low contact angles.) For viscoelastic fluids, the linear scaling of\n$a^3$ with time is replaced by the general result that $a^3(t)$ is proportional\nto the creep compliance $J(t)$.",
        "positive": "Dynamically Generated Patterns in Dense Suspensions of Active Filaments: We use Langevin dynamics simulations to study dynamical behaviour of a dense\nplanar layer of active semi-flexible filaments. Using the strength of active\nforce and the thermal persistence length as parameters, we map a detailed phase\ndiagram and identify several non-equilibrium phases in this system. In addition\nto a slowly flowing melt phase, we observe that for sufficiently high activity,\ncollective flow accompanied by signatures of local polar and nematic order\nappears in the system. This state is also characterised by strong density\nfluctuations. Furthermore, we identify an activity-driven cross-over from this\nstate of coherently flowing bundles of filaments to a phase with no global\nflow, formed by individual filaments coiled into rotating spirals. This\nsuggests a mechanism where the system responds to activity by changing the\nshape of active agents, an effect with no analogue in systems of active\nparticles without internal degrees of freedom."
    },
    {
        "anchor": "Scaling of discrete element model parameters for cohesionless and\n  cohesive solid: One of the major shortcomings of discrete element modelling (DEM) is the\ncomputational cost required when the number of particles is huge, especially\nfor fine powders and/or industry scale simulations. This study investigates the\nscaling of model parameters that is necessary to produce scale independent\npredictions for cohesionless and cohesive solid under quasi-static simulation\nof confined compression and unconfined compression to failure in uniaxial test.\nA bilinear elasto-plastic adhesive frictional contact model was used. The\nresults show that contact stiffness (both normal and tangential) for loading\nand unloading scales linearly with the particle size and the adhesive force\nscales very well with the square of the particle size. This scaling law would\nallow scaled up particle DEM model to exhibit bulk mechanical loading response\nin uniaxial test that is similar to a material comprised of much smaller\nparticles. This is a first step towards a mesoscopic representation of a\ncohesive powder that is phenomenological based to produce the key bulk\ncharacteristics of a cohesive solid and has the potential to gain considerable\ncomputational advantage for industry scale DEM simulations.",
        "positive": "Trapping and hopping of bipolarons in DNA: Su-Schrieffer-Heeger model\n  calculations: With the Su-Schrieffer-Heeger model involving the effects of solvent\npolarization and external electric field, we show that bipolaron maybe more\nstable than two polarons when a dication induced into a DNA stack. Under the\nhigh electric field, the dication can move quite a long distance through the\nDNA by a series of hopping process, partially losing its configuration\ninstantaneously due to the nonadiabatic effects."
    },
    {
        "anchor": "Stable smectic phase in suspensions of polydisperse colloidal platelets\n  with identical thickness: We report the nematic and smectic ordering in a new aqueous suspension of\nmonolayer $\\alpha$-Zirconium phosphate platelets possessing a high\npolydispersity in diameter but uniform thickness. We observe an\nisotropic--nematic transition as the platelet volume fraction increases,\nfollowed by the formation of a smectic, an elusive phase that has been rarely\nseen in discotic liquid crystals. The smectic phase is characterized by X-ray\ndiffraction, high-resolution transmission electron microscopy, and optical\nmicroscopy. The phase equilibria in this highly polydisperse suspension is\nrationalized in terms of a theoretical approach based on density--functional\ntheory.",
        "positive": "Strong dynamical effects during stick-slip adhesive peeling: We consider the classical problem of the stick-slip dynamics observed when\npeeling a roller adhesive tape at a constant velocity. From fast imaging\nrecordings, we extract the dependencies of the stick and slip phases durations\nwith the imposed peeling velocity and peeled ribbon length. Predictions of\nMaugis and Barquins [in Adhesion 12, edited by K.W. Allen, Elsevier ASP,\nLondon, 1988, pp. 205--222] based on a quasistatic assumption succeed to\ndescribe quantitatively our measurements of the stick phase duration. Such\nmodel however fails to predict the full stick-slip cycle duration, revealing\nstrong dynamical effects during the slip phase."
    },
    {
        "anchor": "The N boson time dependent problem: an exact approach with stochastic\n  wave functions: We present a numerically tractable method to solve exactly the evolution of a\nN boson system with binary interactions. The density operator of the system rho\nis obtained as the stochastic average of particular operators |Psi_1><Psi_2| of\nthe system. The states |Psi_{1,2}> are either Fock states |N:phi_{1,2}> or\ncoherent states |coh:phi_{1,2}> with each particle in the state phi_{1,2}. We\ndetermine the conditions on the evolution of phi_{1,2} -which involves a\nstochastic element- under which we recover the exact evolution of rho. We\ndiscuss various possible implementations of these conditions. The well known\npositive P-representation arises as a particular case of the coherent state\nansatz. We treat numerically two examples: a two-mode system and a\none-dimensional harmonically confined gas. These examples, together with an\nanalytical estimate of the noise, show that the Fock state ansatz is the most\npromising one in terms of precision and stability of the numerical solution.",
        "positive": "Flowing active liquids in a pipe: Hysteretic response of polar flocks to\n  external fields: We investigate the response of colloidal flocks to external fields. We first\nshow that individual colloidal rollers align with external flows as would a\nclassical spin with magnetic fields. Assembling polar active liquids from\ncolloidal rollers, we experimentally demonstrate their hysteretic response:\nconfined colloidal flocks can proceed against external flows. We theoretically\nexplain this collective robustness, using an active hydrodynamic description,\nand show how orientational elasticity and confinement protect the direction of\ncollective motion. Finally, we exploit the intrinsic bistability of confined\nactive flows to devise self-sustained microfluidic oscillators."
    },
    {
        "anchor": "Macroscopic Facilitation of Glassy Relaxation Kinetics: Ultra Stable\n  Glass Films with Front-Like Thermal Response: The recent experimental fabrication of ultra stable glass films via vapour\ndeposition [Science 315, 353 (2007)] and the observation of front-like response\nto the annealing of these films [Phys.Rev.Lett. 102, 065503 (2009)], have\nraised important questions about the possibility of manipulating the properties\nof glass films and addressing fundamental questions about kinetics and\nthermodynamics of amorphous materials. Central to both of these issues is the\nneed to establish the essential physics that governs the formation of the\nultra-stable films and their subsequent response. In this paper we demonstrate\nthat a generic model of glassy dynamics can account for the formation of\nultra-stable films, the associated enhancement of relaxation rates by a factor\nof 10^5, the observation of front-like response to temperature jumps and the\ntemperature dependence of the front velocity",
        "positive": "The electronic structure of poly(pyridine-2,5-diyl) investigated by soft\n  x-ray absorption and emission spectroscopies: The electronic structure of the poly-pyridine conjugated polymer has been\ninvestigated by resonant and nonresonant inelastic X-ray scattering and X-ray\nabsorption spectroscopies using synchrotron radiation. The measurements were\nmade for both the carbon and nitrogen contents of the polymer. The analysis of\nthe spectra has been carried out in comparison with molecular orbital\ncalculations taking the repeat-unit cell as a model molecule of the polymer\nchain. The simulations indicate no significant differences in the absorption\nand in the non-resonant X-ray scattering spectra for the different isomeric\ngeometries, while some isomeric dependence of the resonant spectra is\npredicted. The resonant emission spectra show depletion of the {\\pi} electron\nbands in line with symmetry selection and momentum conservation rules. The\neffect is most vizual for the carbon spectra; the nitrogen spectra are\ndominated by lone pair n orbital emission of {\\sigma} symmetry and are less\nfrequency dependent."
    },
    {
        "anchor": "Correlated dynamics of inclusions in a supported membrane: The hydrodynamic theory of heterogeneous fluid membranes is extended to the\ncase of a membrane adjacent to a solid substrate. We derive the coupling\ndiffusion coefficients of pairs of membrane inclusions in the limit of large\nseparation compared to the inclusion size. Two-dimensional compressive stresses\nin the membrane make the coupling coefficients decay asymptotically as $1/r^2$\nwith interparticle distance $r$. For the common case, where the distance to the\nsubstrate is of sub-micron scale, we present expressions for the coupling\nbetween distant disklike inclusions, which are valid for arbitrary inclusion\nsize. We calculate the effect of inclusions on the response of the membrane and\nthe associated corrections to the coupling diffusion coefficients to leading\norder in the concentration of inclusions. While at short distances the response\nis modified as if the membrane were a two-dimensional suspension, the\nlarge-distance response is not renormalized by the inclusions.",
        "positive": "A new look at effective interactions between microgel particles: Thermoresponsive microgels find widespread use as colloidal model systems,\nbecause their temperature-dependent size allows facile tuning of their volume\nfraction \"in situ\". However, an interaction potential unifying their behavior\nacross the entire phase diagram is sorely lacking. Here we investigate microgel\nsuspensions in the fluid regime at different volume fractions and temperatures,\nand in the presence of another population of small microgels, combining\nconfocal microscopy experiments and numerical simulations. We find that\neffective interactions between microgels are clearly temperature dependent. In\naddition, microgel mixtures possess an enhanced stability compared to hard\ncolloid mixtures - a property not predicted by a simple Hertzian model. Based\non numerical calculations we propose a multi-Hertzian model, which reproduces\nthe experimental behaviour for all studied conditions. Our findings highlight\nthat effective interactions between microgels are much more complex than\nusually assumed, displaying a crucial dependence on temperature and the\ninternal core-corona architecture of the particles."
    },
    {
        "anchor": "Following the evolution of glassy states under external perturbations:\n  the full replica symmetry breaking solution: The state-following technique allows the study of metastable glassy states\nunder external perturbations. Here we show how this construction can be used to\nstudy the behavior of glassy states of Hard Spheres in infinite dimensions\nunder compression or shear strain. In a preceding work it has been shown that\nin both cases, when the external perturbation is sufficiently strong, glassy\nstates undergo a second-order transition, called the Gardner transition,\nwhereupon a hierarchical structure of marginal micro-states manifests within\nthe original glass state. The purpose of this work is to study the solution of\nthe state-following construction in this marginal phase. We show that upon\ncompression, close to the jamming transition, the metastable states are\ndescribed by a scaling solution characterized by a set of non-trivial critical\nexponents that agree with the results obtained in a preceding work, and we\ncompute the value of the final jamming density for various glassy states.\nMoreover we show that under the action of the shear strain, beyond the Gardner\npoint, the metastable states can be followed in the marginal phase and we\ndetect an overshoot in the stress-strain curve in agreement with numerical and\nexperimental observations. Finally we further characterize the Gardner\ntransition point by computing both the critical 4-point susceptibility and the\nexponents that characterize the critical slowing down of the dynamics within a\nglassy state close to the transition.",
        "positive": "Under-knotted and over-knotted polymers: compact self-avoiding loops: We present a computer simulation study of the compact self-avoiding loops as\nregards their length and topological state. We use a Hamiltonian closed path on\nthe cubic-shaped segment of a 3D cubic lattice as a model of a compact polymer.\nThe importance of ergodic sampling of all loops is emphasized. We first look at\nthe effect of global topological constraint on the local fractal geometry of a\ntypical loop. We find that even short pieces of a compact trivial knot, or some\nother under-knotted loop, are somewhat crumpled compared to topology-blind\naverage over all loops. We further attempt to examine whether knots are\nlocalized or de-localized along the chain when chain is compact. For this, we\nperform computational decimation and chain coarsening, and look at the\n\"renormalization trajectories\" in the space of knots frequencies. Although not\ncompletely conclusive, our results are not inconsistent with the idea that\nknots become de-localized when the polymer is compact."
    },
    {
        "anchor": "Particle migration in porous media: from the mesoscopic perspective: Convection-diffusion equation is used to describe particle migration process\nin many fields, while it is proposed based on the empirical Fick's law. In this\npaper, with the help of the percolation model, we theoretically investigate the\nparticle migration law in porous media from the mesoscopic perspective, and\nbase on the probabilistic migration characteristic of particles to strictly\nreformulate the convection-diffusion equation. Meanwhile the quantitative\nrelations between the convection, diffusion coefficients and the mesoscopic\nparameters of particle-motion and percolation-configuration are revealed.\nFurthermore, via the Monte-Carlo numerical simulation, we verify the proposed\nmesoscopic particle migration theory and modify the expressions of convection,\ndiffusion coefficients for global applicability. In addition, applicable\nqualification of the proposed mesoscopic theory is given, and relation between\nthe blocking effect parameter and connecting probability of the percolation\nmodel is obtained.",
        "positive": "Anomalous behavior of dispersion of longitudinal and transverse\n  collective excitations in water: We study the dependence of the excitation frequency of water along an\nisochore and an isotherm crossing the region of density anomaly. We have shown\nthat the frequency of the longitudinal excitations demonstrated anomalous\ndependence on temperature along the isochore. At the same time the dependence\nfor both longitudinal and transverse excitation frequencies on density along\nthe isotherm are very modest or even negligible in rather wide range of\ndensities. This kind of behavior also seems anomalous in comparison with the\nordinary liquids."
    },
    {
        "anchor": "Effects of direction reversals on patterns of active filaments: Active matter systems provide fascinating examples of pattern formation and\ncollective motility without counterparts in equilibrium systems. Here, we\nemploy Brownian dynamics simulations to study the collective motion and\nself-organization in systems of self-propelled semiflexible filaments, inspired\nby the gliding motility of \\textit{filamentous Cyanobacteria}. Specifically, we\ninvestigate the influence of stochastic direction reversals on the patterns. We\nexplore pattern formation and dynamics by modulating three relevant physical\nparameters, the bending stiffness, the activity, and the reversal rate. In the\nabsence of reversals, our results show rich dynamical behavior including spiral\nformation and collective motion of aligned clusters of various sizes, depending\non the bending stiffness and self-propulsion force. The presence of reversals\ndiminishes spiral formation and reduces the sizes of clusters or suppresses\nclustering entirely. This homogenizing effect of direction reversals can be\nunderstood as reversals providing an additional mechanism to either unwind\nspirals or to resolve clusters.",
        "positive": "Analysis of the static properties of cluster formations in symmetric\n  linear multiblock copolymers: We use molecular dynamics simulations to study the static properties of a\nsingle linear multiblock copolymer chain under poor solvent conditions varying\nthe block length $N$, the number of blocks $n$, and the solvent quality by\nvariation of the temperature $T$. We study the most symmetrical case, where the\nnumber of blocks of monomers of type A, $n_{A}$, equals that of monomers B,\n$n_{B}$ ($n_{A}=n_{B}=n/2$), the length of all blocks is the same irrespective\nof their type, and potential parameters are also chosen symmetrically, as for a\nstandard Lennard-Jones fluid. Under poor solvent conditions the chains collapse\nand blocks with monomers of the same type form clusters, which are phase\nseparated from the clusters with monomers of the other type. We study the\ndependence of the size of the formed clusters on $n$, $N$ and $T$. Furthermore,\nwe discuss our results with respect to recent simulation data on the phase\nbehaviour of such macromolecules, providing a complete picture for the cluster\nformations in single multiblock copolymer chains under poor solvent conditions."
    },
    {
        "anchor": "Stability and noise in biochemical switches: Many processes in biology, from the regulation of gene expression in bacteria\nto memory in the brain, involve switches constructed from networks of\nbiochemical reactions. Crucial molecules are present in small numbers, raising\nquestions about noise and stability. Analysis of noise in simple reaction\nschemes indicates that switches stable for years and switchable in milliseconds\ncan be built from fewer than one hundred molecules. Prospects for direct tests\nof this prediction, as well as implications, are discussed.",
        "positive": "Ringed spherulitic and undulated textures in the nematic phase of a\n  mixture of trans-4-hexylcyclohexanecarboxylic and benzoic acids: We present a polarising optical microscopy study of a liquid-crystal mixture\nof trans-4-hexylcyclohexanecarboxylic acid (C6) and benzoic acid. Both\nmaterials have carboxylic groups that can form dimers through hydrogen bonding.\nThe mixture is nematic and room temperature and has the clearing point at 88\nCelsius. The nematic phase shows ringed spherulites, sometimes looking like\nspiral structures, and undulated textures, which remain visible heating the\nsample till 71 Celsius. This is the temperature of a texture transition inside\nthe nematic phase."
    },
    {
        "anchor": "Pressure-energy correlations in liquids. V. Isomorphs in generalized\n  Lennard-Jones systems: This series of papers is devoted to identifying and explaining the properties\nof strongly correlating liquids, i.e., liquids with more than 90% correlation\nbetween their virial W and potential energy U fluctuations in the NVT ensemble.\nPaper IV [N. Gnan et al., J. Chem. Phys. v131, 234504 (2009)] showed that\nstrongly correlating liquids have \"isomorphs\", which are curves in the phase\ndiagram along which structure, dynamics, and some thermodynamic properties are\ninvariant in reduced units. In the present paper, using the fact that\nreduced-unit radial distribution functions are isomorph invariant, we derive an\nexpression for the shapes of isomorphs in the WU phase diagram of generalized\nLennard-Jones systems of one or more types of particles. The isomorph shape\ndepends only on the Lennard-Jones exponents; thus all isomorphs of standard\nLennard-Jones systems (with exponents 12 and 6) can be scaled onto to a single\ncurve. Two applications are given. One is testing the prediction that the\nsolid-liquid coexistence curve follows an isomorph by comparing to recent\nsimulations by Ahmed and Sadus [J. Chem. Phys. v131, 174504 (2009)]. Excellent\nagreement is found on the liquid side of the coexistence, whereas the agreement\nis worse on the solid side. A second application is the derivation of an\napproximate equation of state for generalized Lennard-Jones systems by\ncombining the isomorph theory with the Rosenfeld-Tarazona expression for the\ntemperature dependence of potential energy on isochores. It is shown that the\nnew equation of state agrees well with simulations.",
        "positive": "A Deterministic Approach to the Protein Design Problem: We have considered the problem of protein design based on a model where the\ncontact energy between amino acid residues is fitted phenomenologically using\nthe Miyazawa--Jernigan matrix. Due to the simple form of the contact energy\nfunction, an analytical prescription is found which allows us to design\nenergetically stable sequences for fixed amino acid residues compositions and\ntarget structures. The theoretically obtained sequences are compared with real\nproteins and good correspondence is obtained. Finally we discuss the effect of\ndiscrepancies in the procedure used to fit the contact energy on our\ntheoretical predictions."
    },
    {
        "anchor": "Structure of liquid and glassy methanol confined in cylindrical pores: We present a neutron scattering analysis of the density and the static\nstructure factor of confined methanol at various temperatures. Confinement is\nperformed in the cylindrical pores of MCM-41 silicates with pore diameters D=24\nangstrom and D=35 angstrom. A change of the thermal expansivity of confined\nmethanol at low temperature is the signature of a glass transition, which\noccurs at higher temperature for the smallest pore. This is an evidence of a\nsurface induced slowing down of the dynamics of the fluid. The structure factor\npresents a systematic evolution with the pore diameter, which has been analyzed\nin terms of excluded volume effects and fluid-matrix cross-correlation.\nConversely to the case of Van der Waals fluids, it shows that stronger\nfluid-matrix correlations must be invoked most probably in relation with the\nH-bonding character of both methanol and silicate surface.",
        "positive": "Structure and dynamics of a self-propelled semiflexible filament: We investigate structural and dynamical properties of a self-propelled\nfilament using coarse-grained Brownian dynamics simulations. A self-propulsion\nforce is applied along the bond vectors, i.e., tangent to the filament and\ntheir locations are considered in two different manners. In case one, force is\napplied to all beads of the filament, which is termed as homogeneous\nself-propulsion. Here, we obtain a monotonic decrease in the flexibility of the\nfilament with P\\'eclet number. Hence, radius of gyration also displays the same\ntrend. Moreover, the radius of gyration of the filament shows universal\ndependence for various bending rigidities with flexure number. The effective\ndiffusivity of the filament shows enhancement with the active force and it\nincreases linearly with force and bending rigidity. In case two,\nself-propulsion force is applied only to few bond vectors. The location of\nactive forces is chosen in a periodic manner starting from the tail of the\nfilament and leaving the front end without force. In this case, filament\nacquires various structures such as rod-like, helical, circular, and folded\nstates. The transition from several states is understood in terms of\ntangent-tangent correlation, bending energy and torsional order parameter. The\nhelical state is identified through a crossover from exponential to oscillatory\nbehavior of the tangent-tangent correlation. A sudden increase in the bending\nenergy separates a helical to a folded states of the filament."
    },
    {
        "anchor": "Oscillations and damping in the fractional Maxwell materials: This paper examines the oscillatory behaviour of complex viscoelastic systems\nwith power law-like relaxation behaviour. Specifically, we use the fractional\nMaxwell model, consisting of a spring and fractional dashpot in series, which\nproduces a power-law creep behaviour and a relaxation law following the\nMittag-Leffler function. The fractional dashpot is characterised by a parameter\nbeta, continuously moving from the pure viscous behaviour when beta=1 to the\npurely elastic response when beta=0. In this work, we study the general\nresponse function and focus on the oscillatory behaviour of a fractional\nMaxwell system in four regimes: stress impulse, strain impulse, step stress,\nand driven oscillations. The solutions are presented in a format analogous to\nthe classical oscillator, showing how the fractional nature of relaxation\nchanges the long-time equilibrium behaviour and the short-time transient\nsolutions. We specifically test the critical damping conditions in the\nfractional regime, since these have a particular relevance in biomechanics.",
        "positive": "Migration of semiflexible polymers in microcapillary flow: The non-equilibrium structural and dynamical properties of a semiflexible\npolymer confined in a cylindrical microchannel and exposed to a Poiseuille flow\nis studied by mesoscale hydrodynamic simulations. For a polymer with a length\nhalf of its persistence length, large variations in orientation and\nconformations are found as a function of radial distance and flow strength. In\nparticular, the polymer exhibits U-shaped conformations near the channel\ncenter. Hydrodynamic interactions lead to strong cross-streamline migration.\nOutward migration is governed by the polymer orientation and the corresponding\nanisotropy in its diffusivity. Strong tumbling motion is observed, with a\ntumbling time which exhibits the same dependence on Peclet number as a polymer\nin shear flow."
    },
    {
        "anchor": "The flow and evolution of ice-sucrose crystal mushes: We study the rheology of suspensions of ice crystals at moderate to high\nvolume fractions in a sucrose solution in which they are partially soluble; a\nmodel system for a wide class of crystal mushes or slurries. Under step changes\nin shear rate, the viscosity changes to a new `relaxed' value over several\nminutes, in a manner well fitted by a single exponential. The behavior of the\nrelaxed viscosity is power-law shear thinning with shear rate, with an exponent\nof $-1.76 \\pm 0.25$, so that shear stress falls with increasing shear rate. On\nlonger timescales, the crystals ripen (leading to a falling viscosity) so that\nthe mean radius increases with time to the power $0.14 \\pm 0.07$. We speculate\nthat this unusually small exponent is due to the interaction of classical\nripening dynamics with abrasion or breakup under flow. We compare the\nrheological behavior to mechanistic models based on flow-induced aggregation\nand breakup of crystal clusters, finding that the exponents can be predicted\nfrom liquid phase sintering and breakup by brittle fracture.",
        "positive": "Structural and Dynamical Anomalies of a Gaussian Core Fluid: a Mode\n  Coupling Theory Study: We present a theoretical study of transport properties of a liquid comprised\nof particles uist1:/home/sokrates/egorov/oldhome/Pap41/Submit > m abs.tex We\npresent a theoretical study of transport properties of a liquid comprised of\nparticles interacting via Gaussian Core pair potential. Shear viscosity and\nself-diffusion coefficient are computed on the basis of the mode-coupling\ntheory, with required structural input obtained from integral equation theory.\nBoth self-diffusion coefficient and viscosity display anomalous density\ndependence, with diffusivity increasing and viscosity decreasing with density\nwithin a particular density range along several isotherms below a certain\ntemperature. Our theoretical results for both transport coefficients are in\ngood agreement with the simulation data."
    },
    {
        "anchor": "Complete breakdown of the Debye model of rotational relaxation near the\n  isotropic-nematic phase boundary: Effects of intermolecular correlations in\n  orientational dynamics: The Debye-Stokes-Einstein (DSE) model of rotational diffusion predicts that\nthe rotational correlation times $\\tau_{l}$ vary as $[l(l+1)]^{-1}$, where $l$\nis the rank of the orientational correlation function (given in terms of the\nLegendre polynomial of rank $l$). One often finds significant deviation from\nthis prediction, in either direction. In supercooled molecular liquids where\nthe ratio $\\tau_{1}/\\tau_{2}$ falls considerably below three (the Debye limit),\none usually invokes a jump diffusion model to explain the approach of the ratio\n$\\tau_{1}/\\tau_{2}$ to unity. Here we show in a computer simulation study of a\nstandard model system for thermotropic liquid crystals that this ratio becomes\nmuch less than unity as the isotropic-nematic phase boundary is approached from\nthe isotropic side. Simultaneously, the ratio $\\tau_2/\\eta$ (where $\\eta$ is\nthe shear viscosity of the liquid) becomes {\\it much larger} than hydrodynamic\nvalue near the I-N transition. We have also analyzed the break down of the\nDebye model of rotational diffusion in ratios of higher order rotational\ncorrelation times. We show that the break down of the DSE model is due to the\ngrowth of orientational pair correlation and provide a mode coupling theory\nanalysis to explain the results.",
        "positive": "Multi-Particle Collision Dynamics for a coarse-grained model of soft\n  colloids: The growing interest in the dynamical properties of colloidal suspensions,\nboth in equilibrium and under an external drive such as shear or pressure flow,\nrequires the development of accurate methods to correctly include hydrodynamic\neffects due to the suspension in a solvent. In the present work, we generalize\nMulti-Particle Collision Dynamics (MPCD) to be able to deal with soft,\npolymeric colloids. Our methods build on the knowledge of the monomer density\nprofile that can be obtained from monomer-resolved simulations without\nhydrodynamics or from theoretical arguments. We hereby propose two different\napproaches. The first one simply extends the MPCD method by including in the\nsimulations effective monomers with a given density profile, thus neglecting\nmonomer-monomer interactions. The second one considers the macromolecule as a\nsingle penetrable soft colloid (PSC), which is permeated by an inhomogeneous\ndistribution of solvent particles. By defining an appropriate set of rules to\ncontrol the collision events between the solvent and the soft colloid, both\nlinear and angular momenta are exchanged. We apply these methods to the case of\nlinear chains and star polymers for varying monomer lengths and arm number,\nrespectively, and compare the results for the dynamical properties with those\nobtained within monomer-resolved simulations. We find that the effective\nmonomer method works well for linear chains, while the PSC method provides very\ngood results for stars. These methods pave the way to extend MPCD treatments to\ncomplex macromolecular objects such as microgels or dendrimers and to work with\nsoft colloids at finite concentrations."
    },
    {
        "anchor": "Molecular motors enhance microtubule lattice plasticity: Microtubules are key structural elements of living cells that are crucial for\ncell division, intracellular transport and motility. Recent experiments have\nshown that microtubule severing proteins and molecular motors stimulate the\ndirect and localized incorporation of free tubulin into the shaft. However, a\nmechanistic picture how microtubule associated proteins affect the lattice is\ncompletely missing. Here we theoretically explore a potential mechanism of\nlattice turnover stimulated by processive molecular motors in which a weak\ntransient destabilization of the lattice by the motor stepping promotes the\nformation of mobile vacancies. In the absence of free tubulin the defect\nrapidly propagates leading to a complete fracture. In the presence of free\ntubulin, the motor walk induces a vacancy drift in the direction opposite of\nthe motor walk. The drift is accompanied by the direct and localized\nincorporation of free tubulin along the trajectory of the vacancy. Our results\nare consistent with experiments and strongly suggest that a weak lattice-motor\ninteraction is responsible for an augmented microtubule shaft plasticity.",
        "positive": "Long Wavelength Fluctuations and the Glass Transition in 2D and 3D: Phase transitions significantly differ between two-dimensional and\nthree-dimensional systems, but the influence of dimensionality on the glass\ntransition is unresolved. We use microscopy to study colloidal systems as they\napproach their glass transitions at high concentrations, and find differences\nbetween 2D and 3D. We find that in 2D particles can undergo large displacements\nwithout changing their position relative to their neighbors, in contrast with\n3D. This is related to Mermin-Wagner long-wavelength fluctuations that\ninfluence phase transitions in 2D. However, when measuring particle motion only\nrelative to their neighbors, 2D and 3D have similar behavior as the glass\ntransition is approached, showing that the long wavelength fluctuations do not\ncause a fundamental distinction between 2D and 3D glass transitions."
    },
    {
        "anchor": "Plasticity and dynamical heterogeneity in driven glassy materials: Many amorphous glassy materials exhibit complex spatio-temporal mechanical\nresponse and rheology, characterized by an intermittent stress-strain response\nand a fluctuating velocity profile. Under quasistatic and athermal deformation\nprotocols this heterogeneous plastic flow was shown to be composed of plastic\nevents of various sizes. In this paper, through numerical study of a 2D LJ\namorphous solid, we generalize the study of the heterogeneous dynamics of\nglassy materials to the finite shear-rate and temperature case. The global\nmechanical response obtained through the use of Molecular Dynamics is shown to\nconverge to the quasistatic limit obtained with an energy minimization\nprotocol. The detailed analysis of the plastic deformation at different shear\nrates shows that the glass follows different flow regimes. At sufficiently low\nshear rates the mechanical response reaches a shear-rate independent regime\nthat exhibits all the characteristics of the quasistatic response (finite size\neffects, yield stress...). At intermediate shear rates the rheological\nproperties are determined by the externally applied shear-rate. Finally at\nhigher shear the system reaches a shear-rate independent homogeneous regime.\nThe existence of these three regimes is also confirmed by the detailed analysis\nof the atomic motion. The computation of the four-point correlation function\nshows that the transition from the shear-rate dominated to the quasistatic\nregime is accompanied by the growth of a dynamical cooperativity length scale\n$\\xi$ that is shown to diverge with shear rate. This divergence is compared\nwith the prediction of a simple model that assumes the diffusive propagation of\nplastic events.",
        "positive": "Models of plastic depinning of driven disordered systems: Two classes of models of driven disordered systems that exhibit\nhistory-dependent dynamics are discussed. The first class incorporates local\ninertia in the dynamics via nonmonotonic stress transfer between adjacent\ndegrees of freedom. The second class allows for proliferation of topological\ndefects due to the interplay of strong disorder and drive. In mean field theory\nboth models exhibit a tricritical point as a function of disorder strength. At\nweak disorder depinning is continuous and the sliding state is unique. At\nstrong disorder depinning is discontinuous and hysteretic."
    },
    {
        "anchor": "Numerical Evaluation of the Statistical Properties of a Potential Energy\n  Landscape: The techniques which allow the numerical evaluation of the statistical\nproperties of the potential energy landscape for models of simple liquids are\nreviewed and critically discussed. Expressions for the liquid free energy and\nits vibrational and configurational components are reported. Finally, a\npossible model for the statistical properties of the landscape, which appears\nto describe correctly fragile liquids in the region where equilibrium\nsimulations are feasible, is discussed.",
        "positive": "Competitive adsorption of surfactants and polymers on colloids by means\n  of mesoscopic simulations: The study of competitive and cooperative adsorption of functionalized\nmolecules such as polymers, rheology modifiers and surfactant molecules on\ncolloidal particles immersed in a solvent is undertaken using coarse grained,\ndissipative particle dynamics simulations. The results show that a complex\npicture emerges from the simulations, one where dispersants and surfactants\nadsorb cooperatively up to certain concentrations, on colloidal particles, but\nas the surfactant concentration increases it leads to dispersant desorption.\nThe presence of rheology modifying agents in the colloidal dispersion adds\ncomplexity through the association of surfactant micelles to hydrophobic sites\nof these agents. Analysis of the simulation results reported here point clearly\nto the self association of the hydrophobic sites along the different polymer\nmolecules as the mechanism responsible for their competitive and cooperative\nadsorption."
    },
    {
        "anchor": "Unexpected ductility in semiflexible polymer glasses with $N_e =\n  C_\\infty$: Semiflexible polymer glasses (SPGs), including those formed by the recently\nsynthesized semiflexible conjugated polymers (SCPs), are expected to be brittle\nbecause classical formulas for their craze extension ratio $\\lambda_{\\rm\ncraze}$ and fracture stretch $\\lambda_{\\rm frac}$ predict that systems with\n$N_e = C_\\infty$ have $\\lambda_{\\rm craze} = \\lambda_{\\rm frac} = 1$ and hence\ncannot be deformed to large strains. Using molecular dynamics simulations, we\nshow that in fact such glasses can form stable crazes with $\\lambda_{\\rm craze}\n\\simeq N_e^{1/4} \\simeq C_\\infty^{1/4}$, and that they fracture at\n$\\lambda_{\\rm frac} = (3N_e^{1/2} - 2)^{1/2} \\simeq (3C_\\infty^{1/2} -\n2)^{1/2}$. We argue that the classical formulas for $\\lambda_{\\rm craze}$ and\n$\\lambda_{\\rm frac}$ fail to describe SPGs' mechanical response because they do\nnot account for Kuhn segments' ability to stretch during deformation.",
        "positive": "Phase diagram and structural properties of a simple model for one-patch\n  particles: We study the thermodynamic and structural properties of a simple, one-patch\nfluid model using the reference hypernetted-chain (RHNC) integral equation and\nspecialized Monte Carlo simulations. In this model, the interacting particles\nare hard spheres, each of which carries a single identical,\narbitrarily-oriented, attractive circular patch on its surface; two spheres\nattract via a simple square-well potential only if the two patches on the\nspheres face each other within a specific angular range dictated by the size of\nthe patch. For a ratio of attractive to repulsive surface of 0.8, we construct\nthe RHNC fluid-fluid separation curve and compare with that obtained by Gibbs\nensemble and grand canonical Monte Carlo simulations. We find that RHNC\nprovides a quick and highly reliable estimate for the position of the\nfluid-fluid critical line. In addition, it gives a detailed (though\napproximate) description of all structural properties and their dependence on\npatch size."
    },
    {
        "anchor": "Can one predict a drop contact angle?: The study of wetting phenomena is of great interest due to the multifaceted\ntechnological applications of hydrophobic and hydrophilic surfaces. The\ntheoretical approaches proposed by Wenzel and later by Cassie and Baxter to\ndescribe the behaviour of a droplet of water on a rough solid were extensively\nused and improved to characterize the apparent contact angle of a droplet.\nHowever, the equilibrium hypothesis implied in these models means that they are\nnot always predictive of experimental contact angles due to strong\nmetastabilities typically occurring on heterogeneous surfaces. A predictive\nscheme for contact angle is thus urgently needed both to characterise a surface\nby contact angle measurements and to design superhydrophobic and oleophobic\nsurfaces with the desired properties, e.g., contact angle hysteresis. In this\nwork a combination of Monte Carlo simulation and the string method is employed\nto calculate the free energy profile of a liquid droplet deposited on a\npillared surface. For the analyzed surfaces, we show that there is only one\nminimum of the free energy that corresponds to the superhydrophobic wetting\nstate while the wet state can present multiple minima. Furthermore, when the\nsurface roughness decreases the amount of local minima observed in the free\nenergy profile increases.",
        "positive": "Adhesion-induced fingering instabilities in thin elastic films under\n  strain: In this study, thin elastic films supported on a rigid substrate are brought\ninto contact with a spherical glass indenter. Upon contact, adhesive fingers\nemerge at the periphery of the contact patch with a characteristic wavelength.\nElastic films are also pre-strained along one axis before initiation of\ncontact, causing the fingering pattern to become anisotropic and align with the\naxis along which the strain was applied. This transition from isotropic to\nanisotropic patterning is characterized quantitatively and a simple model is\ndeveloped to understand the origin of the anisotropy."
    },
    {
        "anchor": "Fluid driven fingering instability of a confined elastic meniscus: When a fluid is pumped into a cavity in a confined elastic layer, at a\ncritical pressure, destabilizing fingers of fluid invade the elastic solid\nalong its meniscus (Saintyves, Dauchot, and Bouchaud, 2013). These fingers\noccur without fracture or loss of adhesion and are reversible, disappearing\nwhen the pressure is decreased. We develop an asymptotic theory of pressurized\nhighly elastic layers trapped between rigid bodies to explain these\nobservations, with predictions for the critical fluid pressure for fingering,\nand the finger wavelength. We also show that the theory links this fluid-driven\nfingering with a similar transition driven instead by transverse stretching of\nthe elastic layer. We further verify these predictions by using finite-element\nsimulations on the two systems which show that, in both cases, the fingering\ntransition is first-order (sudden) and hence has a region of bistability. Our\npredictions are in good agreement with recent observations of this elastic\nanalog of the classical Saffman-Taylor interfacial instability in\nhydrodynamics.",
        "positive": "Vortex Multiplication in Applied Flow: the Precursor to Superfluid\n  Turbulence: The dynamics of quantized vortices in rotating $^3$He-B is investigated in\nthe low density (single-vortex) regime as a function of temperature. An abrupt\ntransition is observed at $0.5 T_{\\rm c}$. Above this temperature the number of\nvortex lines remains constant, as they evolve to their equilibrium positions.\nBelow this temperature the number of vortices increases linearly in time until\nthe vortex density has grown sufficiently for turbulence to switch on. On the\nbasis of numerical calculations we suggest a mechanism responsible for vortex\nformation at low temperatures and identify the mutual friction parameter which\ngoverns its abrupt temperature dependence."
    },
    {
        "anchor": "Orienting Ion-Containing Block Copolymers Using AC Electric Field: We consider orientation mechanisms for block copolymers in an electric field.\nTheoretical and experimental studies have shown that nonuniformity of the\ndielectric constant gives rise to a preferred orientation of the melt with\nrespect to the applied field. We show that the presence of ions, as found in\nanionically prepared copolymers, may increase the alignment effect markedly.\nTime-varying (ac) and static (dc) fields are considered within a unified\nframework. We find that orientation of block copolymers can in principle be\nachieved without a dielectric contrast if there is a mobility contrast. The\npresence of ions is especially important at small field frequencies, as is in\nmost experiments. Unlike the no-ions case, it is found that orienting forces\ndepend on the polymer chain lengths. The mobile-ions mechanism suggested here\ncan be used to reduce the magnitude of orienting fields as well as to\ndiscriminate between block copolymers of different lengths.",
        "positive": "On the modulational stability of Gross-Pittaevskii type equations in 1+1\n  dimensions: The modulational stability of the nonlinear Schr{\\\"o}dinger (NLS) equation is\nexamined in the cases with linear and quadratic external potential. This study\nis motivated by recent experimental studies in the context of matter waves in\nBose-Einstein condensates. The linear case can be examined by means of the\nTappert transformation and can be mapped to the NLS in the appropriate\n(constant acceleration) frame. The quadratic case can be examined by using a\nlens-type transformation that converts it into a regular NLS with an additional\nlinear growth term."
    },
    {
        "anchor": "A mesoscopic theory to describe the flexibility regulation in F-actin\n  networks: An approach of phase transitions with nonlinear elasticity: The synthetic actin network arouses great interest as bio-material due to its\nsoft and wet nature that mimics many biological scaffolding structures. Inside\nthe cell, the actin network is regulated by tens of actin-binding proteins\n(ABP's), which make for a highly complex system with several emergent\nbehaviours. In particular, calponin is an ABP that was identified as an actin\nstabiliser, but whose mechanism is still poorly understood. Recent experiments\nusing an in vitro model system of cross-linked actin with calponin and large\ndeformation bulk rheology, found that networks with basic calponin exhibited a\ndelayed onset and were able to withstand a higher maximal strain before\nsoftening.\n  In this work, we show that the difference between the two networks, with and\nwithout calponin, not only provides bundle flexibility. But, also encodes\nalterations in the pre-strain and the regulation of the crosslinks adhesion\nenergy to define the new yielding point. We verify these effects theoretically\nusing nonlinear continuum mechanics for the semiflexible and crosslinked\nnetwork. In addition, the alterations over the microstructure are described by\nthe definition of an interaction parameter $\\Gamma$ according the formalism of\nLandau. According to this simple model we demonstrates that the interaction\nparameter can describe the experimental observations following an scaling\nexponent as $\\Gamma \\sim \\mid c-c_{cr} \\mid^{1/2}$, where $c$ is the ratio\nbetween concentration of calponin and actin. This result provides interesting\nfeedback to improve our understanding of several mechano-biological pathways.",
        "positive": "Dilute polymer solutions under shear flow: comprehensive qualitative\n  analysis using a bead-spring chain model with a FENE-Fraenkel spring: Although the non-equilibrium behaviour of polymer solutions is generally well\nunderstood, particularly in extensional flow, there remain several unanswered\nquestions for dilute solutions in simple shear flow, and full quantitative\nagreement with experiments has not been achieved. For example, experimental\nviscosity data exhibit qualitative differences in shear-thinning exponents,\nshear rate for onset of shear-thinning and high-shear Newtonian plateaus\ndepending on polymer semiflexibility, contour length and solvent quality. While\npolymer models are able to incorporate all of these effects through various\nspring force laws, bending potentials, excluded volume (EV) potentials, and\nhydrodynamic interaction (HI), the inclusion of each piece of physics has not\nbeen systematically matched to experimentally observed behaviour. Furthermore,\nattempts to develop multiscale models (in the sense of representing an\narbitrarily small or large polymer chain) which can make quantitative\npredictions are hindered by the lack of ability to fully match the results of\nbead-rod models, often used to represent a polymer chain at the Kuhn step\nlevel, with bead-spring models, which take into account the entropic\nelasticity.In light of these difficulties, this work aims to develop a general\nmodel based on the so-called FENE-Fraenkel spring, originally formulated by\nLarson and coworkers [J. Chem. Phys. 124 (2006), 10.1063/1.2161210], which can\nspan the range from rigid rod to traditional entropic spring, as well as\ninclude a bending potential, EV and HI. As we show, this model can reproduce,\nand smoothly move between, a wide range of previously observed polymer solution\nrheology in shear flow."
    },
    {
        "anchor": "Random copolymers at a selective interface: many chains with excluded\n  volume interactions: We investigate numerically, using the bond-fluctuation model, the adsorption\nof many random AB--copolymers with excluded volume interactions at the\ninterface between two solvents. We find two regimes, controlled by the total\nnumber of polymers. In the first (dilute) regime, the copolymers near the\ninterface extend parallel to it, while in the second regime they extend\nperpendicular to it. The density at the interface and the density in the bulk\ndepend differently on the total number of copolymers: In the first regime the\ndensity at the interface increases more rapidly then in the bulk, whereas the\nopposite is true in the second regime.",
        "positive": "Multi-component structure of nonlinear excitations in systems with\n  length-scale competition: We investigate the properties of nonlinear excitations in different types of\nsoliton bearing systems with long-range dispersive interaction. We show that\nlength-scale competition in such systems universally results in a\nmulti-component structure of nonlinear excitations and can lead to a new type\nof multistability: coexistence of different nonlinear excitations at the same\nvalue of the spectral parameter (i.e., velocity in the case of anharmonic\nlattices or frequency in nonlinear Schroedinger models)."
    },
    {
        "anchor": "Phase transitions in biological systems with many components: Biological mixtures such as the cytosol may consist of thousands of distinct\ncomponents. There is now a substantial body of evidence showing that, under\nphysiological conditions, intracellular mixtures can phase separate into\nspatially distinct regions with differing compositions. In this paper we\npresent numerical evidence indicating that such spontaneous\ncompartmentalization exploits general features of the phase diagram of a\nmulticomponent biomolecular mixture. In particular, we show that demixed\ndomains are likely to segregate when the variance in the inter-molecular\ninteraction strengths exceeds a well-defined threshold. Multiple distinct\nphases are likely to become stable under very similar conditions, which can\nthen be tuned to achieve multiphase coexistence. As a result, only minor\nadjustments to the composition of the cytosol or the strengths of the\ninter-molecular interactions are needed to regulate the formation of different\ndomains with specific compositions, implying that phase separation is a robust\nmechanism for creating spatial organization. We further predict that this\nfunctionality is only weakly affected by increasing the number of components in\nthe system. Our model therefore suggests that, for purely physico-chemical\nreasons, biological mixtures are naturally poised to undergo a small number of\ndemixing phase transitions.",
        "positive": "Effect of Sinusoidal Surface Roughness and Energy on the Orientation of\n  Cylinder-Forming Block Copolymer Thin Films: We explore the relative stability of three possible orientations of\ncylinder-forming di-block copolymer on a sinusoidally corrugated substrate. The\ncylinders can be aligned either parallel to the substrate, with their long axis\nbeing oriented along or orthogonal to the corrugation trenches, or\nperpendicular to the substrate. Using self-consistent field theory, we\ninvestigate the influence of substrate roughness and surface preference on the\nphase transition between the three orientations. When the substrate preference,\n$u$, towards one of components is small, increasing the substrate roughness\ninduces a phase transition from parallel to perpendicular cylindrical phase.\nHowever, when $u$ is large, the parallel orientation is more stable than the\nperpendicular one. Within this parallel phase, increasing the substrate\nroughness leads to a transition of cylinder orientation changing from being\northogonal to parallel to the trench long axis. Increasing the substrate\npreference leads to an opposite transition from parallel to orthogonal to the\ntrenches. Furthermore, we predict that the perpendicular cylinder phase is\neasier to be obtained when the unidirectional corrugation is along the longer\nunit vector of the hexagonal packing than when it is along the shorter unit\nvector. Our results qualitatively agree with previous experiments, and\ncontribute towards applications of the cylinder-forming block copolymer in\nnanotechnology."
    },
    {
        "anchor": "Like-charge attraction in a one-dimensional setting: the importance of\n  being odd: From cement cohesion to DNA condensation, a proper statistical physics\ntreatment of systems with long range forces is important for a number of\napplications in physics, chemistry, and biology. We compute here the effective\nforce between fixed charged macromolecules, screened by oppositely charged\nmobile ions (counterions). We treat the problem in a one dimensional\nconfiguration, that allows for interesting discussion and derivation of exact\nresults, remaining at a level of mathematical difficulty compatible with an\nundergraduate course. Emphasis is put on the counter-intuitive but fundamental\nphenomenon of like-charge attraction, that our treatment brings for the first\ntime to the level of undergraduate teaching. The parity of the number of\ncounterions is shown to play a prominent role, which sheds light on the binding\nmechanism at work when like-charge macromolecules do attract.",
        "positive": "Invariance properties of bacterial random walks in complex structures: Motile cells often explore natural environments characterized by a high\ndegree of structural complexity. Moreover cell motility is also intrinsically\nnoisy due to spontaneous random reorientation and speed fluctuations. This\ninterplay of internal and external noise sources gives rise to a complex\ndynamical behavior that can be strongly sensitive to details and hard to model\nquantitatively. In striking contrast to this general picture we show that the\nmean residence time of swimming bacteria inside artificial complex\nmicrostructures, can be quantitatively predicted by a generalization of a\nrecently discovered invariance property of random walks. We find that\nvariations in geometry and structural disorder have a dramatic effect on the\ndistributions of path length while mean values are strictly constrained by the\nsole free volume to surface ratio. Biological implications include the\npossibility of predicting and controlling the colonization of complex natural\nenvironments using only geometric informations."
    },
    {
        "anchor": "Diffusion of an Active Particle Bound to a Generalized Elastic Model:\n  Fractional Langevin Equation: We investigate the influence of a self-propelling, out-of-equilibrium active\nparticle on generalized elastic systems, including flexible and semiflexible\npolymers, fluid membranes, and fluctuating interfaces, while accounting for\nlong-ranged hydrodynamic effects. We derive the fractional Langevin equation\ngoverning the dynamics of the active particle, as well as that of any other\npassive particle (or probe) bound to the elastic system. This equation\ndemonstrates analytically how the active particle dynamics is influenced by the\ninterplay of both the non-equilibrium force and of the viscoelastic\nenvironment. Our study explores the diffusional behavior emerging for both the\nactive particle and a distant probe.The active particle undergoes three\ndifferent surprising and counterintuitive regimes identified by the distinct\ndynamical time-scales: a pseudo-ballistic initial phase, a drastic decrease of\nthe mobility and an asymptotic subdiffusive regime.",
        "positive": "Tunable Memory and Activity of Quincke Particles in Micellar Fluid: Memory can remarkably modify the collective behaviors of active particles. We\nshow that in a micellar fluid, Quincke particles driven by a square-wave\nelectric field exhibit a frequency-dependent memory. Upon increasing the\nfrequency, a memory of directions emerges whereas the activity of particles\ndecreases. As the activity is dominated by interaction, Quincke particles\naggregate and form dense clusters in which the memory of the direction is\nfurther enhanced due to the stronger electric interactions. The\ndensity-dependent memory and activity result in dynamic heterogeneity in\nflocking and offer new opportunity for study of collective motions."
    },
    {
        "anchor": "Stokes-Einstein diffusion of colloids in nematics: We report the experimental observation of anisotropic diffusion of\npolystyrene particles immersed in a lyotropic liquid crystal with two different\nanchoring conditions. Diffusion is shown to obey the Stokes-Einstein law for\nparticle diameters ranging from 190 nm up to 2 micron. In the case of prolate\nmicelles, the beads diffuse four times faster along the director than in\nperpendicular directions. In the theory part we present a perturbative approach\nto the Leslie-Ericksen equations and relate the diffusion coefficients to the\nMiesovicz viscosity parameters.We provide explicit formulas for the cases of\nuniform director field and planar anchoring conditions which are then discussed\nin view of the data. As a general rule, we find that the inequalities {\\eta}b <\n{\\eta}a < {\\eta}c, satisfied by various liquid crystals of rodlike molecules,\nimply Dpar > Dperp.",
        "positive": "Relaxation of the Induced Orientational Order in the Isotropic Phase of\n  Nematic Polymer: Orientational dynamics in the isotropic phase of a comb-shaped nematic\npolymer with mesogenic and functional side groups was studied using the Kerr\neffect and dielectric spectroscopy. For the first time, it was found that in a\nmesogenic polymer, in contrast to low-molecular-weight mesogens, the relaxation\nof the electric birefringence of a melt above the temperature of the\nnematic-isotropic phase transition can be presented by a sum of several\nexponential processes, two of which play a decisive role. These main processes\nreplace each other in a temperature range of about fifty degrees. Dielectric\nspectroscopy also made it possible to distinguish two processes of\norientational relaxation: the first is due to rotation of the side mesogenic\ngroups, and the second is associated with motion of the main chain segments."
    },
    {
        "anchor": "Structure and thermodynamics of the primitive model electrolyte in a\n  charged matrix: The evaluation of the Madden-Glandt approximation: We compared the results of the Madden-Glandt (MG) integral equation\napproximation for partly-quenched systems with the commonly accepted formalism\nof Given and Stell (GS). The system studied was a +1:-1 restricted primitive\nmodel (RPM) electrolyte confined in a quenched +1:-1 RPM matrix. A\nrenormalization scheme was proposed for a set of MG replica Ornstein-Zernike\nequations. Long-ranged direct and total correlation functions, describing the\ninteractions between the annealed electrolyte species within the same replicas\nand between the annealed and matrix particles, appeared to be the same for MG\nand GS approach. Both versions of the theory give very similar results for the\nstructure and thermodynamics of an annealed subsystem. Differences between\nexcess internal energy, excess chemical potential, and isothermal\ncompressibility become pronounced only at high concentrations of matrix\nparticles.",
        "positive": "Focal Conic Flower Textures at Curved Interfaces: Focal conic domains (FCDs) in smectic-A liquid crystals have drawn much\nattention both for their exquisitely structured internal form and for their\nability to direct the assembly of micro- and nanomaterials in a variety of\npatterns. A key to directing FCD assembly is control over the eccentricity of\nthe domain. Here, we demonstrate a new paradigm for creating spatially varying\nFCD eccentricity by confining a hybrid-aligned smectic with curved interfaces.\nIn particular, we manipulate interface behavior with colloidal particles in\norder to experimentally produce two examples of what has recently been dubbed\nthe flower texture, where the focal hyperbolae diverge radially outward from\nthe center of the texture, rather than inward as in the canonical eventail or\nfan texture. We explain how this unconventional assembly can arise from\nappropriately curved interfaces. Finally, we present a model for this system\nthat applies the law of corresponding cones, showing how FCDs may be embedded\nsmoothly within a \"background texture\" of large FCDs and concentric spherical\nlayers, in a manner consistent with the qualitative features of the smectic\nflower. Such understanding could potentially lead to disruptive liquid crystal\ntechnologies beyond displays, including patterning, smart surfaces, microlens\narrays, sensors and nanomanufacturing."
    },
    {
        "anchor": "Slow coarsening in jammed athermal soft particle suspensions: We simulate a densely jammed, athermal assembly of repulsive soft particles\nimmersed in a solvent. Starting from an initial condition corresponding to a\nquench from a high temperature, we find non-trivial slow dynamics driven by a\ngradual release of stored elastic energy, with the root mean squared particle\nspeed decaying as a power law in time with a fractional exponent. This decay is\naccompanied by the presence within the assembly of spatially localised and\ntemporally intermittent `hot-spots' of non-affine deformation, connected by\nlong-ranged swirls in the velocity field, reminiscent of the local plastic\nevents and long-ranged elastic propagation that have been intensively studied\nin sheared amorphous materials. The pattern of hot-spots progressively\ncoarsens, with the hot-spot size and separation slowly growing over time, and\nthe associated velocity correlation length increasing as a sublinear power law.\nEach individual spot however exists only transiently, within an overall picture\nof strongly intermittent dynamics.",
        "positive": "Second-order Barker-Henderson perturbation theory for the phase behavior\n  of polydisperse Morse hard-sphere mixture: We propose an extension of the second-order Barker-Henderson perturbation\ntheory for polydisperse hard-sphere multi-Morse mixture. To verify the accuracy\nof the theory, we compare its predictions for the limiting case of monodisperse\nsystem, with predictions of the very accurate reference hypernetted chain\napproximation. The theory is used to describe the liquid-gas phase behavior of\nthe mixture with different type and different degree of polydispersity. In\naddition to the regular liquid-gas critical point, we observe the appearance of\nthe second critical point induced by polydispersity. With polydispersity\nincrease, the two critical points merge and finally disappear. The\ncorresponding cloud and shadow curves are represented by the closed curves with\n'liquid' and 'gas' branches of the cloud curve almost coinciding for higher\nvalues of polydispersity. With a further increase of polydispersity, the cloud\nand shadow curves shrink and finally disappear. Our results are in agreement\nwith the results of the previous studies carried out on the qualitative van der\nWaals level of description."
    },
    {
        "anchor": "Active shape-morphing elastomeric colloids in short-pitch cholesteric\n  liquid crystals: Active elastomeric liquid crystal particles with initial cylindrical shapes\nare obtained by means of soft lithography and polymerization in a strong\nmagnetic field. Gold nanocrystals infiltrated into these particles mediate\nenergy transfer from laser light to heat, so that the inherent coupling between\nthe temperature-dependent order and shape allows for dynamic morphing of these\nparticles and well-controlled stable shapes. Continuous changes of particle\nshapes are followed by their spontaneous realignment and transformations of\ndirector structures in the surrounding cholesteric host, as well as locomotion\nin the case of a nonreciprocal shape morphing. These findings bridge the fields\nof liquid crystal solids and active colloids, may enable shape-controlled\nself-assembly of adaptive composites and light-driven micromachines, and can be\nunderstood by employing simple symmetry considerations along with electrostatic\nanalogies.",
        "positive": "Non-Equilibrium View of the Amorphous Solidification of Liquids with\n  Competing Interactions: The interplay between short-range attractions and long-range repulsions\n(SALR) characterizes the so called liquids with competing interactions, which\nare known to exhibit a variety of equilibrium and non-equilibrium phases. The\ntheoretical description of the phenomenology associated to glassy or gel states\nin these systems has to take into account both, the presence of thermodynamic\ninstabilities (such as those defining the spinodal line and the so called\n$\\lambda$ line) and the limited capability to describe genuine non-equilibrium\nprocesses from first principles. Here we report the first application of the\nnon-equilibrium self-consistent generalized Langevin equation theory, to the\ndescription of the dynamical arrest processes that occur in SALR systems after\nbeing instantaneously quenched into a state point in the regions of\nthermodynamic instability. The physical scenario predicted by this theory\nreveals an amazing interplay between the thermodynamically-driven\ninstabilities, favoring equilibrium macro- and micro-phase separation, and the\nkinetic arrest mechanisms, favoring non-equilibrium amorphous solidification of\nthe liquid into an unexpected variety of glass and gel states."
    },
    {
        "anchor": "Determination of the symmetry classes of orientational ordering tensors: The orientational order of nematic liquid crystals is traditionally studied\nby means of the second-rank ordering tensor $\\mathbb{S}$. When this is\ncalculated through experiments or simulations, the symmetry group of the phase\nis not known \\emph{a-priori}, but needs to be deduced from the numerical\nrealisation of $\\mathbb{S}$, which is affected by numerical errors. There is no\ngenerally accepted procedure to perform this analysis. Here, we provide a new\nalgorithm suited to identifying the symmetry group of the phase. As a by\nproduct, we prove that there are only five phase-symmetry classes of the\nsecond-rank ordering tensor and give a canonical representation of $\\mathbb{S}$\nfor each class. The nearest tensor of the assigned symmetry is determined by\ngroup-projection. In order to test our procedure, we generate uniaxial and\nbiaxial phases in a system of interacting particles, endowed with $D_{\\infty\nh}$ or $D_{2h}$, which mimic the outcome of Monte-Carlo simulations. The actual\nsymmetry of the phases is correctly identified, along with the optimal choice\nof laboratory frame.",
        "positive": "Reversible plasticity in amorphous materials: A fundamental assumption in our understanding of material rheology is that\nwhen microscopic deformations are reversible, the material responds elastically\nto external loads. Plasticity, i.e. dissipative and irreversible macroscopic\nchanges in a material, is assumed to be the consequence of irreversible\nmicroscopic events. Here we show direct evidence for reversible plastic events\nat the microscopic scale in both experiments and simulations of two-dimensional\nfoam. In the simulations, we demonstrate a link between reversible plastic\nrearrangement events and pathways in the potential energy landscape of the\nsystem. These findings represent a fundamental change in our understanding of\nmaterials--microscopic reversibility does not necessarily imply elasticity."
    },
    {
        "anchor": "Simple measurement of silanol (OH) concentration in silanol-terminated\n  silicone fluids: This article reports a simple technique for measuring the concentration of\nsilanol groups in a silanol-terminated polydimethylsiloxane fluid. That\ntechnique requires only a common drying agent and a Zeolite, can be completed\nin minutes, and is accurate to about 10%.",
        "positive": "Crystallization and glass transition in supercooled binary Lennard-Jones\n  liquids: The classic Kob-Andersen (KA) binary Lennard-Jones mixtures which are\ndesigned to prevent crystallization has been extensively studied in simulation\nof slow dynamics. Although crystallization can occur if a liquid system is\ncooled slowly, so far the KA model has not been crystallized. Here we report\nusing molecular simulation the observation of crystal growth in the supercooled\nKA liquids. The onset of crystallization is observed occurring at temperature\n$T_c= 0.55$ which is higher than the glass transition temperature of\n$T_g=0.40$. We further examine the statistical distribution of single particle\ndisplacements in crystallization and close to glass transition. The\ndisplacement distribution for crystallization exhibits a power-law decay,\nwhereas the distribution for glassy relaxation reflects a Gaussian center,\nterminated with an exponential tail (namely dynamic heterogeneity). Finally, we\npredict in order to crystalize KA liquids the cooling rate is approximately\nequal to $10^{-22}$, which is about 15 odder lower than the typical MD cooling\nrate."
    },
    {
        "anchor": "Modeling the deep drawing of a 3D woven fabric with a second gradient\n  model: Experimental testing on dry woven fabrics exhibits a complex set of evidences\nthat are difficult to be completely described using classical continuum models.\nThe aim of this paper is to show how the introduction of energy terms related\nto the micro-deformation mechanisms of the fabric, in particular to the bending\nstiffness of the yarns, helps in the modeling of the mechanical behavior of\nthis kind of materials. To this aim, a second gradient, hyperelastic, initially\northotropic continuum theory is proposed to model fibrous composite interlocks\nat finite strains. In particular, the present work explores the relationship\nbetween the onset of wrinkling appearing during the simulation of the deep\ndrawing of a woven fabric and the use of a second gradient model. It is shown\nthat the introduction of second gradient terms accounting for the description\nof in-plane and out-of-plane bending rigidities, decreases the onset of\nwrinkles during the simulation of deep-drawing.\n  In this work, a quadratic energy, roughly proportional to the square of the\ncurvature of the fibers, is presented and implemented in the simulations. This\nsimple constitutive assumption allows to clearly show the effects of the second\ngradient energy on both the wrinkling description and the numerical stability\nof the model. The results obtained in second gradient simulations are\ndescriptive of the experimental evidence of deep drawing whose description is\ntargeted in this work. The present paper provides additional evidence of the\nfact that first gradient continuum theories alone cannot be considered fully\ndescriptive of the behavior of dry woven composite reinforcements. On the other\nhand, the proposed second gradient model for fibrous composite reinforcements\nopens the way both to the more accurate simulation of complex forming processes\nand to the possibility of controlling the onset of wrinkles.",
        "positive": "Optical tweezers microrheology maps the dynamics of strain-induced local\n  inhomogeneities in entangled polymers: Optical tweezers microrheology (OTM) offers a powerful approach to probe the\nnonlinear response of complex soft matter systems, such as networks of\nentangled polymers, over wide-ranging spatiotemporal scales. OTM can also\nuniquely characterize the microstructural dynamics that lead to the intriguing\nnonlinear rheological properties that these systems exhibit. However, the\nstrain in OTM measurements, applied by optically forcing a micro-probe through\nthe material, induces network inhomogeneities in and around the strain path,\nand the resultant flow field complicates the measured response of the system.\nThrough a robust set of custom-designed OTM protocols, coupled with modeling\nand analytical calculations, we characterize the time-varying inhomogeneity\nfields induced by OTM measurements. We show that post-strain homogenization\ndoes not interfere with the intrinsic stress relaxation dynamics of the system,\nrather it manifests as an independent component in the stress decay, even in\nhighly nonlinear regimes such as with the microrheological-LAOS (mLAOS)\nprotocols we introduce. Our specific results show that Rouse-like elastic\nretraction, rather than disentanglement and disengagement, dominates the\nnonlinear stress relaxation of entangled polymers at micro- and meso- scales.\nThus, our study opens up possibilities of performing precision nonlinear\nmicrorheological measurements, such as mLAOS, on a wide range of complex\nmacromolecular systems."
    },
    {
        "anchor": "A perspective on the fragility of glass-forming liquids: We discuss possible extraneous effects entering in the conventional measures\nof \"fragility\" at atmospheric pressure that may obscure a characterization of\nthe genuine super-Arrhenius slowdown of relaxation. We first consider the role\nof density, which increases with decreasing temperature at constant pressure,\nand then the potential influence of the high-temperature dynamical behavior and\nof the associated activation energy scale. These two effects involve both\nthermodynamic parameters and the strength of the \"bare\" activation energy\nreflecting the specific bonding between neighboring molecules. They vary from\nsystem to system with, most likely, little connection with any putative\ncollective behavior associated with glass formation. We show how to scale these\neffects out by refining the definition of fragility and modifying the\ncelebrated Angell plot. We dedicate this note to our great and so inspiring\nfriend, Austen Angell, and associate in this tribute another dear colleague who\ndied too soon, Daniel Kivelson.",
        "positive": "Far-from-equilibrium Sheared Colloidal Liquids: Disentangling\n  Relaxation, Advection, and Shear-induced Diffusion: Using high-speed confocal microscopy, we measure the particle positions in a\ncolloidal suspension under large amplitude oscillatory shear. Using the\nparticle positions we quantify the in situ anisotropy of the pair-correlation\nfunction -- a measure of the Brownian stress. From these data, we find two\ndistinct types of responses as the system crosses over from equilibrium to\nfar-from-equilibrium states. The first is a nonlinear amplitude saturation that\narises from shear-induced advection, while the second is a linear frequency\nsaturation due to competition between suspension relaxation and shear rate. In\nspite of their different underlying mechanisms, we show that all the data can\nbe scaled onto a master curve that spans the equilibrium and\nfar-from-equilibrium regimes, linking small amplitude oscillatory to continuous\nshear. This observation illustrates a colloidal analog of the Cox-Merz rule and\nits microscopic underpinning. Brownian Dynamics simulations show that\ninterparticle interactions are sufficient for generating both experimentally\nobserved saturations."
    },
    {
        "anchor": "Hierarchical microphase separation in non-conserved active mixtures: Non-equilibrium phase separating systems with reactions can break\ntime-reversal symmetry (TRS) in two distinct ways. Firstly, the conservative\nand non-conservative sectors of the dynamics can be governed by incompatible\nfree energies; when both sectors are present, this is the leading-order TRS\nviolation, captured in its simplest form by 'Model AB'. Second, the diffusive\ndynamics can break TRS in its own right. This happens only at higher order in\nthe gradient expansion (but is the leading behaviour without reactions present)\nand is captured by 'Active Model B+' (AMB+). Each of the two mechanisms can\nlead to microphase separation, by quite different routes. Here we introduce\nModel AB+, for which both mechanisms are simultaneously present, and show that\nfor slow reaction rates the system can undergo a new type of hierarchical\nmicrophase separation, whereby a continuous phase of fluid 1 contains large\ndroplets of fluid 2 within which small droplets of fluid 1 are continuously\ncreated and then absorbed into the surrounding fluid-1 phase. In this state of\n'bubbly microphase separation' the small-scale 1-in-2 droplets arise by the\nconservative diffusive dynamics with the larger scale 2-in-1 structure governed\nby the nonconservative reactions.",
        "positive": "Rapid Conformational Analysis of Semi-Flexible Liquid Crystals: We present an approach for rapid conformational analysis of semi-flexible\nliquid crystals. We use a simple graphical user interface (GUI) tool that\nleverages rules-based methods for efficient generation of bend-angle\ndistributions, offering a significant improvement over traditional\nsingle-conformer analysis. Our methods demonstrated proficiency in\napproximating molecular shapes comparable to those obtained from molecular\ndynamics (MD) simulations, albeit with notable deviations in the under sampling\nof hairpin conformations and oversampling of extended configurations.\nRe-evaluation of existing data revealed an apparent weak correlation between\nNTB transition temperatures and bend angles, underscoring the complexity of\nmolecular shapes beyond mere geometry. Furthermore, we integrated this\nconformational analysis into a pipeline of algorithmic molecular design,\nutilizing a fragment-based genetic algorithm to generate novel\ncyanobiphenyl-containing materials. This integration opens new avenues for the\nexploration of liquid crystalline materials, particularly in systems where\nsystematic conformer searches are impractical, such as large oligomeric\nsystems. Our findings highlight the potential and growing importance of\ncomputational approaches in accelerating the design and synthesis of\nnext-generation liquid crystalline materials."
    },
    {
        "anchor": "Electrophoresis of active Janus particles: We theoretically consider the dynamics of a self-propelled active Janus motor\nmoving in an external electric field. The external field can manipulate the\nroute of a Janus particle and enforce it to move towards the desired targets.\nTo investigate the trajectory of this active motor, we use a perturbative\nscheme. At the leading orders of surface activity of the Janus particle and\nalso the external field, the orientational dynamics of the Janus particles\nbehave like a mathematical pendulum with an angular the velocity that is\nsensitive to both the electric field and surface activity of the motor.",
        "positive": "Long Range Stress Correlations in the Inherent Structures of Liquids at\n  Rest: Simulation studies of the atomic shear stress in the local potential energy\nminima (inherent structures) are reported for binary liquid mixtures in 2D and\n3D. These inherent structure stresses are fundamental to slow stress relaxation\nand high viscosity in supercooled liquids. We find that the atomic shear stress\nin the inherent structures (IS) of both liquids at rest exhibits slowly\ndecaying anisotropic correlations. We show that the stress correlations\ncontributes significantly to the variance of the total shear stress of the IS\nconfigurations and consider the origins of the anisotropy and spatial extent of\nthe stress correlations."
    },
    {
        "anchor": "Application of Onsager's variational principle to the dynamics of a\n  solid toroidal island on a substrate: In this paper, we consider the capillarity-driven evolution of a solid\ntoroidal island on a flat rigid substrate, where mass transport is controlled\nby surface diffusion. This problem is representative of the geometrical\ncomplexity associated with the solid-state dewetting of thin films on\nsubstrates. We apply Onsager's variational principle to develop a general\napproach for describing surface diffusion-controlled problems. Based on this\napproach, we derive a simple, reduced-order model and obtain an analytical\nexpression for the rate of island shrinking and validate this prediction by\nnumerical simulations based on a full, sharp-interface model. We find that the\nrate of island shrinking is proportional to the material constants $B$ and the\nsurface energy density $\\gamma_0$, and is inversely proportional to the island\nvolume $V_0$. This approach represents a general tool for modeling interface\ndiffusion-controlled morphology evolution.",
        "positive": "Partial clustering prevents global crystallization in a binary 2D\n  colloidal glass former: A mixture of two types of super-paramagnetic colloidal particles with long\nrange dipolar interaction is confined by gravity to a flat interface of a\nhanging water droplet. The particles are observed by video microscopy and the\ndipolar interaction strength is controlled via an external magnetic field. The\nsystem is a model system to study the glass transition in 2D, and it exhibits\npartial clustering of the small particles. This clustering is strongly\ndependent on the relative concentration $\\xi$ of big and small particles.\nHowever, changing the interaction strength $\\Gamma$ reveals that the clustering\ndoes not depend on the interaction strength. The partial clustering scenario is\nquantified using Minkowski functionals and partial structure factors. Evidence\nthat partial clustering prevents global crystallization is discussed."
    },
    {
        "anchor": "Linear stability analysis of transverse dunes: Sand-moving winds blowing from a constant direction in an area of high sand\navailability form transverse dunes, which have a fixed profile in the direction\northogonal to the wind. Here we show, by means of a linear stability analysis,\nthat transverse dunes are intrinsically unstable. Any along-axis perturbation\non a transverse dune amplify in the course of dune migration due to the\ncombined effect of two main factors, namely: the lateral transport through\navalanches along the dune's slip-face, and the scaling of dune migration\nvelocity with the inverse of the dune height. Our calculations provide a\nquantitative explanation for recent observations from experiments and numerical\nsimulations, which showed that transverse dunes moving on the bedrock cannot\nexist in a stable form and decay into a chain of crescent-shaped barchans.",
        "positive": "Frame tension governs the thermal fluctuations of a fluid membrane: new\n  evidence: Two different tensions can be defined for a fluid membrane: the internal\ntension, $\\gamma$, conjugated to the real membrane area in the Hamiltonian, and\nthe frame tension, $\\tau$, conjugated to the projected (or frame) area.\nAccording to the standard statistical description of a membrane, the\nfluctuation spectrum is governed by $\\gamma$. However, using rotational\ninvariance arguments, several studies argued that fluctuation spectrum must be\ngoverned by the frame tension $\\tau$ instead. These studies disagree on the\norigin of the result obtained with the standard description yet: either a\nmiscounting of configurations, quantified with the integration measure, or the\nuse of a quadratic approximation of the Helfrich Hamiltonian. Analyzing the\nsimplest case of a one-dimensional membrane, for which arc length offers a\nnatural parametrization, we give a new proof that the fluctuations are driven\nby $\\tau$, and show that the origin of the issue with the standard description\nis a miscounting of membrane configurations. The origin itself of this\nmiscounting depends on the thermodynamic ensemble in which calculations are\nmade."
    },
    {
        "anchor": "Plateau border bulimia transition: discontinuities expected in three\n  simple experiments on 2D liquid foams: We describe the geometry of foams squeezed between two solid plates (2D GG\nfoams) in two main asymptotic regimes: fully dry floor tiles and dry pancakes.\nWe predict an abrupt transition between both regimes, with a substantial change\nin the Plateau border radius. This should be observable in different types of\nexperiments on such 2D GG foams: when foam is being progressively dried or\nwetted, when it is being squeezed further or stretched, when it coarsens\nthrough film breakage or Oswald ripening.",
        "positive": "Excitations of Bose-Einstein condensates in optical lattices: In this paper we examine the excitations observable in atoms confined in an\noptical lattice around the superfluid-insulator transition. We use increases in\nthe number variance of atoms, subsequent to tilting the lattice as the primary\ndiagnostic of excitations in the lattice. We show that this locally determined\nquantity should be a robust indicator of coherence changes in the atoms\nobserved in recent experiments. This was found to hold for commensurate or\nnon-commensurate fillings of the lattice, implying our results will hold for a\nwide range of physical cases. Our results are in good agreement with the\nquantitative factors of recent experiments. We do, howevers, find extra\nfeatures in the excitation spectra. The variation of the spectra with the\nduration of the perturbation also turns out to be an interesting diagnostic of\natom dynamics."
    },
    {
        "anchor": "Effective diffusivity of microswimmers in a crowded environment: The microalga Chlamydomonas Reinhardtii (CR) is used here as a model system\nto study the effect of complex environments on the swimming of micro-organisms.\nIts motion can be modelled by a run and tumble mechanism so that it describes a\npersistent random walk from which we can extract an effective diffusion\ncoefficient for the large-time dynamics. In our experiments, the complex medium\nconsists in a series of pillars that are designed in a regular lattice using\nsoft lithography microfabrication. The cells are then introduced in the\nlattice, and their trajectories within the pillars are tracked and analyzed.\nThe effect of the complex medium on the swimming behaviour of microswimmers is\nanalyzed through the measure of relevant statistical observables. In\nparticular, the mean correlation time of direction and the effective diffusion\ncoefficient are shown to decrease when increasing the density of pillars. This\nprovides some bases of understanding for active matter in complex environments.",
        "positive": "Trajectories of loose sand samples in the Phase Space of Soil Mechanics: In general, the evolution of soil submitted to simple stress-strain paths is\ncharacterised using the 3d phase space (v,p',q) i.e. (specific volume, mean\nintergranular pressure, deviatoric stress q. When uniaxial compressions is\nperformed at constant lateral pressure p' or at constant mean pressure p', one\nfinds that all trajectories end up at a line of attracting point called the\ncritical-state line via the surface of Roscoe or of Hvorslev depending if the\ninitial volume is the loosest possible one (at a given p') or densest.\nTrajectories of weakly dense samples are not often reported in this phase\nspace. We find here that they shall present some sigmoid shape as it can be\nfound from soil mechanics argument. This seems to indicate that Roscoe's\nsurface shall exhibit a singularity at the critical point."
    },
    {
        "anchor": "Evolution of rarefaction pulses into vortex rings: The two-dimensional solitary waves of the Gross-Pitaevskii equation in the\nKadomtsev-Petviashvili limit are unstable with respect to three-dimensional\nperturbations. We elucidate the stages in the evolution of such solutions\nsubject to perturbations perpendicular to the direction of motion. Depending on\nthe energy (momentum) and the wavelength of the perturbation different types of\nthree-dimensional solutions emerge. In particular, we present new periodic\nsolutions having very small energy and momentum per period. These solutions\nalso become unstable and this secondary instability leads to vortex ring\nnucleation.",
        "positive": "Biomimetic membranes of lipid-peptide model systems prepared on solid\n  support: The structure of membrane-active peptides and their interaction with lipid\nbilayers can be studied in oriented lipid membranes deposited on solid\nsubstrates. Such systems are desirable for a number of surface-sensitive\ntechniques. Here we focus on structural characterization by x-ray and neutron\nreflectivity and give an account of recent progress in sample preparation and\nmeasurements. We show that the degree of mesoscopic disorder in the films can\nsignificantly influence the scattering curves. Static defects should be\nminimized by optimization of the preparation techniques and their presence must\nbe taken into account in the modelling. Examples are given for alamethicin and\nmagainin in bilayers of different phosphocholines."
    },
    {
        "anchor": "Failure of classical elasticity in auxetic foams: A recent derivation [P.H. Mott and C.M. Roland, Phys. Rev. B 80, 132104\n(2009).] of the bounds on Poisson's ratio, v, for linearly elastic materials\nshowed that the conventional lower limit, -1, is wrong, and that v cannot be\nless than 0.2 for classical elasticity to be valid. This is a significant\nresult, since it is precisely for materials having small values of v that\ndirect measurements are not feasible, so that v must be calculated from other\nelastic constants. Herein we measure directly Poisson's ratio for four\nmaterials, two for which the more restrictive bounds on v apply, and two having\nvalues below this limit of 0.2. We find that while the measured v for the\nformer are equivalent to values calculated from the shear and tensile moduli,\nfor two auxetic materials (v < 0), the equations of classical elasticity give\ninaccurate values of v. This is experimental corroboration that the correct\nlower limit on Poisson's ratio is 0.2 in order for classical elasticity to\napply.",
        "positive": "Genetic algorithms predict formation of exotic ordered configurations\n  for two-component dipolar monolayers: We employ genetic algorithms (GA), which allow for an unbiased search for the\nglobal minimum of energy landscapes, to identify the ordered equilibrium\nconfigurations formed by binary dipolar systems confined on a plane. A large\nvariety of arrangements is identified, the complexity of which grows with\nincreasing asymmetry between the two components and with growing concentration\nof the small particles. The effects of the density are briefly discussed and a\ncomparison with results obtained via conventional lattice-sum minimization is\npresented. Our results can be confirmed by experiments involving Langmuir\nmonolayers of polystyrene dipolar spheres or super-para-magnetic colloids\nconfined on the air-water interface and polarized by an external, perpendicular\nmagnetic field."
    },
    {
        "anchor": "Elasto-plastic flow of a foam around an obstacle: We simulate quasistatic flows of an ideal two-dimensional monodisperse foam\naround different obstacles, both symmetric and asymmetric, in a channel. We\nrecord both pressure and network contributions to the drag and lift forces, and\nstudy them as a function of obstacle geometry. We show that the drag force\nincreases linearly with the cross section of an obstacles. The lift on an\nasymmetric aerofoil-like shape is negative and increases with its arc length,\nmainly due to the pressure contribution.",
        "positive": "Fluctuations in Shear-Jammed States: A Statistical Ensemble Approach: Granular matter exists out of thermal equilibrium, i.e. it is athermal. While\nconventional equilibrium statistical mechanics is not useful for characterizing\ngranular materials, the idea of constructing a statistical ensemble analogous\nto its equilibrium counterpart to describe static granular matter was proposed\nby Edwards and Oakshott more than two decades ago. Recent years have seen\nseveral implementations of this idea. One of these is the stress ensemble,\nwhich is based on properties of the force moment tensor, and applies to\nfrictional and frictionless grains. We demonstrate the full utility of this\nstatistical framework in shear jammed (SJ) experimental states [1,2], a special\nclass of granular solids created by pure shear, which is a strictly\nnon-equilbrium protocol for creating solids. We demonstrate that the stress\nensemble provides an excellent quantitative description of fluctuations in\nexperimental SJ states. We show that the stress fluctuations are controlled by\na single tensorial quantity: the angoricity of the system, which is a direct\nanalog of the thermodynamic temperature. SJ states exhibit significant\ncorrelations in local stresses and are thus inherently different from\ndensity-driven, isotropically jammed (IJ) states."
    },
    {
        "anchor": "Topological defects of integer charge in cell monolayers: Many cell types spontaneously order like nematic liquid crystals, and, as\nsuch, they form topological defects. While defects with topological charge\n$\\pm$1/2 are common in cell monolayers, the defects with charge $\\pm$1,\nrelevant in the formation of protrusions and for cell migration in living\nsystems, are more elusive. We use topographical patterns to impose topological\ncharge of $\\pm$1 in controlled locations in cell monolayers. We compare the\nbehavior of 3T6 fibroblasts and EpH-4 epithelial cells on such patterns,\ncharacterizing the degree of alignment, the cell density near the defects, and\ntheir behavior at the defect core. The patterned substrates provide the right\nconditions to observe isotropic packing of 3T6 cells in the +1 defects. We also\nobserve density variation in the 3T6 monolayers near both types of defects over\nthe same length-scale. These results indicate a defect core size of\n150$\\mu$m-200$\\mu$m, with isotropic packing possible in the +1 defects and, in\nother cases, a defect core with rich internal structure.",
        "positive": "The micromechanics of nonlinear plastic modes: Nonlinear plastic modes (NPMs) are collective displacements that are\nindicative of imminent plastic instabilities in elastic solids. In this work we\nformulate the atomistic theory that describes the reversible evolution of NPMs\nand their associated stiffnesses under external deformations. The\ndeformation-dynamics of NPMs is compared to those of the analogous observables\nderived from atomistic linear elastic theory, namely destabilizing eigenmodes\nof the dynamical matrix and their associated eigenvalues. The key result we\npresent and explain is that the dynamics of NPMs and of destabilizing\neigenmodes under external deformations follow different scaling laws with\nrespect to the proximity to imminent instabilities. In particular,\ndestabilizing modes vary with a singular rate, whereas NPMs' exhibit no such\nsingularity. As a result, NPMs converge much earlier than destabilizing\neigenmodes to their common final form at plastic instabilities. This dynamical\ndifference between NPMs and linear destabilizing eigenmodes underlines the\nusefulness of NPMs for predicting the locus and geometry of plastic\ninstabilities, compared to their linear-elastic counterparts."
    },
    {
        "anchor": "Branches of triangulated origami near the unfolded state: Origami structures are characterized by a network of folds and vertices\njoining unbendable plates. For applications to mechanical design and\nself-folding structures, it is essential to understand the interplay between\nthe set of folds in the unfolded origami and the possible 3D folded\nconfigurations. When deforming a structure that has been folded, one can often\nlinearize the geometric constraints, but the degeneracy of the unfolded state\nmakes a linear approach impossible there. We derive a theory for the\nsecond-order infinitesimal rigidity of an initially unfolded triangulated\norigami structure and use it to study the set of nearly-unfolded configurations\nof origami with four boundary vertices. We find that locally, this set consists\nof a number of distinct \"branches\" which intersect at the unfolded state, and\nthat the number of these branches is exponential in the number of vertices. We\nfind numerical and analytical evidence that suggests that the branches are\ncharacterized by choosing each internal vertex to either \"pop up\" or \"pop\ndown\". The large number of pathways along which one can fold an\ninitially-unfolded origami structure strongly indicate that a generic structure\nis likely to become trapped in a \"misfolded\" state. Thus, new techniques for\ncreating self-folding origami are likely necessary; controlling the popping\nstate of the vertices may be one possibility.",
        "positive": "Stress-induced modification of the boson peak scaling behavior: The scaling behavior of the so-called boson peak in glass-formers and its\nrelation to the elastic properties of the system remains a source of\ncontroversy. Here, the boson peak in a binary reactive mixture is measured by\nRaman scattering (i) on cooling the unreacted mixture well below its glass\ntransition temperature and (ii) after quenching to very low temperature the\nmixture at different times during isothermal polymerization. These different\npaths to the glassy phase are able to generate glasses with different amounts\nof residual stresses, as evidenced by the departure of the elastic moduli from\na Cauchy-like relationship. We find that the scaling behavior of the boson peak\nwith the properties of the elastic medium --- as measured by the Debye\nfrequency --- holds for states in which the system is able to release internal\nstress and breaks down in the presence of residual stresses. These findings\nprovide new insight into the boson peak behavior and are able to reconcile the\napparently conflicting results presented in literature."
    },
    {
        "anchor": "Glassy dynamics of sticky hard spheres beyond the mode-coupling regime: Sticky hard spheres, i.e., hard particles decorated with a short-ranged\nattractive interaction potential, constitute a relatively simple model with\nhighly non-trivial glassy dynamics. The mode-coupling theory of the glass\ntransition (MCT) offers a qualitative account of the complex reentrant dynamics\nof sticky hard spheres, but the predicted glass transition point is notoriously\nunderestimated. Here we apply an improved first-principles-based theory,\nreferred to as generalized mode-coupling theory (GMCT), to sticky hard spheres.\nThis theoretical framework seeks to go beyond MCT by hierarchically expanding\nthe dynamics in higher-order density correlation functions -- an approach that\nmay become exact if sufficiently many correlations are taken into account. We\npredict the phase diagrams from the first few levels of the GMCT hierarchy and\nthe dynamics-related critical exponents, all of which are much closer to the\nempirical observations than MCT. Notably, the prominent reentrant glassy\ndynamics, the glass-glass transition, and the higher-order bifurcation\nsingularity classes ($A_3$ and $A_4$) of sticky hard spheres are found to be\npreserved within GMCT at arbitrary order. Moreover, we demonstrate that when\nthe hierarchical order of GMCT increases, the effect of the short-ranged\nattractive interactions becomes more evident in the dynamics. This implies that\nGMCT is more sensitive to subtle microstructural differences than MCT, and that\nthe framework provides a promising first-principles approach to systematically\ngo beyond the MCT regime.",
        "positive": "Test of molecular mode coupling theory: A first resume: We report recent progress on the test of mode coupling theory for molecular\nliquids (MMCT) for molecules of arbitrary shape. The MMCT equations in the long\ntime limit are solved for supercooled water including all molecular degrees of\nfreedom. In contrast to our earlier treatment of water as a linear molecule, we\nfind that the glass transition temperature $T_c$ is overestimated by the theory\nas was found in the case of simple liquids. The nonergodicity parameters are\ncalculated from the \"full\" set of MMCT-equations truncated at $l_{co}=2$. These\nresults are compared $(i)$ with the nonergodicity parameters from MMCT with\n$l_{co}=2$ in the \"dipole\" approximation $n=n'=0$ and the diagonalization\napproximation $n=n'=0$,$l=l'$ and $(ii)$ with the corresponding results from a\nMD-simulation. This work supports the possibility that a reduction to the most\nprominent correlators may constitute a valid approximation for solving the MMCT\nequations for rigid molecules."
    },
    {
        "anchor": "Lane formation in driven colloidal mixtures: is it continuous or\n  discontinuous?: Binary mixtures of oppositely charged colloids driven by an electric field\nare shown to exhibit a nonequilibrium transition towards lane formation if the\ndriving force is increased. Brownian dynamics computer simulations and\nreal-space experiments are employed to study hysteresis effects in an order\nparameter measuring the extent of lane formation upon increasing and decreasing\nthe driving force. Both from simulation and experiment, we find that lane\nformation due to electrical fields is continuous. However, simulations show a\ndiscontinuous transition if the driving force is gravity.",
        "positive": "Statistical mechanics of bend flexoelectricity and the twist-bend phase\n  in bent-core liquid crystals: We develop a Landau theory for bend flexoelectricity in liquid crystals of\nbent-core molecules. In the nematic phase of the model, the bend flexoelectric\ncoefficient increases as we reduce the temperature toward the nematic to polar\nphase transition. At this critical point, there is a second order transition\nfrom high-temperature uniform nematic phase to low-temperature nonuniform polar\nphase composed of twist-bend or splay-bend deformations. To test the\npredictions of Landau theory, we perform Monte Carlo simulations to find the\ndirector and polarization configurations as functions of temperature, applied\nelectric field, and interaction parameters."
    },
    {
        "anchor": "On the origin of diverse time scales in the protein hydration layer\n  solvation dynamics: A molecular dynamics simulation study: In order to inquire the microscopic origin of observed multiple time scales\nin solvation dynamics we carry out several computer experiments. We perform\natomistic molecular dynamics simulations on three protein-water systems namely,\nLysozyme, Myoglobin and sweet protein Monellin. In these experiments we mutate\nthe charges of the neighbouring amino acid side chains of certain natural\nprobes (Tryptophan) and also freeze the side chain motions. In order to\ndistinguish between different contributions, we decompose the total solvation\nenergy response in terms of various components present in the system. This\nallows us to capture the interplay among different self and cross-energy\ncorrelation terms. Freezing the protein motions removes the slowest component\nthat results from side chain fluctuations, but a part of slowness remains. This\nleads to the conclusion that the slow component in the ~20-80 ps range arises\nfrom slow water molecules present in the hydration layer. While the more than\n100 ps component may arise from various sources namely, adjacent charges in\namino acid side chains, the water molecules that are hydrogen bonded to them\nand a dynamically coupled motion between side chain and water. The charges, in\naddition, enforce a structural ordering of nearby water molecules and helps to\nform local long-lived hydrogen bonded network. Further separation of the\nspatial and temporal responses in solvation dynamics reveals different roles of\nhydration and bulk water. We find that the hydration layer water molecules are\nlargely responsible for the slow component whereas the initial ultrafast decay\narise predominantly (~80%) due to the bulk. This agrees with earlier\ntheoretical observations. We also attempt to rationalise our results with the\nhelp of a molecular hydrodynamic theory that was developed using classical time\ndependent density functional theory in a semi quantitative manner.",
        "positive": "Multiphysics model of chemical aging in frictional contacts: An increase of static friction during stationary contacts of two solids due\nto interfacial chemical bonding has been reported in multiple experiments.\nHowever, the physics underlying such frictional aging is still not fully\nunderstood because it involves multiple physical and chemical effects coupled\nwith each other, making direct interpretation of experimental results\ndifficult. Here, we develop a multiphysics chemical aging model that combines\ncontact mechanics, mechanochemistry, and interfacial chemical reaction\nkinetics. Our model predicts that aging is proportional to normal loads in a\nlow-load regime and becomes nonlinear at higher loads. We also discovered a\nnonmonotonic temperature dependence of aging with a peak near room temperature.\nIn addition, our simulations provide insights into contributions from specific\nphysical/chemical effects on the overall aging. Our model shows quantitative\nagreement with available single-asperity experiments on silica-silica\ninterfaces, and it provides a framework for building a chemical aging model for\nother material systems with arbitrary types of physical and chemical effects\ninvolved."
    },
    {
        "anchor": "Dynamics and correlation length scales of a glass-forming liquid in\n  quiescent and sheared conditions: We numerically study dynamics and correlation length scales of a colloidal\nliquid in both quiescent and sheared conditions to further understand the\norigin of slow dynamics and dynamic heterogeneity in glass-forming systems. The\nsimulation is performed in a weakly frustrated two-dimensional liquid, where\nlocally preferred order is allowed to develop with increasing density. The\nfour-point density correlations and bond-orientation correlations, which have\nbeen frequently used to capture dynamic and static length scales $\\xi$ in a\nquiescent condition, can be readily extended to a system under steady shear in\nthis case. In the absence of shear, we confirmed the previous findings that the\ndynamic slowing down accompanies the development of dynamic heterogeneity. The\ndynamic and static length scales increase with $\\alpha$-relaxation time\n$\\tau_{\\alpha}$ as power-law $\\xi\\sim\\tau_{\\alpha}^{\\mu}$ with $\\mu>0$. In the\npresence of shear, both viscosity and $\\tau_{\\alpha}$ have power-law dependence\non shear rate in the marked shear thinning regime. However, dependence of\ncorrelation lengths cannot be described by power laws in the same regime.\nFurthermore, the relation $\\xi\\sim\\tau_{\\alpha}^{\\mu}$ between length scales\nand dynamics holds for not too strong shear where thermal fluctuations and\nexternal forces are both important in determining the properties of dense\nliquids. Thus, our results demonstrate a link between slow dynamics and\nstructure in glass-forming liquids even under nonequilibrium conditions.",
        "positive": "Solidity of viscous liquids. V. Long-wavelength dominance of the\n  dynamics: This paper is the fifth in a series exploring the physical consequences of\nthe solidity of glass-forming liquids. Paper IV proposed a model where the\ndensity field is described by a time-dependent Ginzburg-Landau equation of the\nnonconserved type with rates in $k$ space of the form $\\Gamma_0+Dk^2$. The\nmodel assumes that $D\\gg\\Gamma_0a^2$ where $a$ is the average intermolecular\ndistance; this inequality expresses a long-wavelength dominance of the dynamics\nwhich implies that the Hamiltonian (free energy) to a good approximation may be\ntaken to be ultralocal. In the present paper we argue that this is the simplest\nmodel consistent with the following three experimental facts: 1) Viscous\nliquids approaching the glass transition do not develop long-range order; 2)\nThe glass has lower compressibility than the liquid; 3) The alpha process\ninvolves several decades of relaxation times shorter than the mean relaxation\ntime. The paper proceeds to list six further experimental facts characterizing\nequilibrium viscous liquid dynamics and shows that these are readily understood\nin terms of the model; some are direct consequences, others are quite natural\nwhen viewed in light of the model."
    },
    {
        "anchor": "Deformability and Solvent Penetration in Soft Nanoparticles at\n  Liquid-Liquid Interfaces: Soft nanoparticles hold promise as smart emulsifiers due to their high degree\nof deformability, permeability and stimuli responsive properties. By means of\nlarge-scale simulations we investigate the structural properties of nanogels at\nliquid-liquid (A-B) interfaces and the miscibility of the liquids inside the\nnanogels, covering the whole range of interfacial strength from the limit of\nsingle-liquid to the case of stiff interfaces. To study the role of the\ninternal architecture and deformability of the nanogel we simulate a realistic\ndisordered and an ideal regular network, for a broad range of cross-linking\ndegrees. Unlike in previous investigations on liquid miscibility, excluded\nvolume interactions are considered for both the monomers and the explicit\nsolvent particles. The nanogel permeability is analysed by using an unbiased\ngrid representation that accounts for the surface fluctuations and adds to the\ndensity profiles the exact number of liquid particles inside the nanogel. The\nbetter packing efficiency of the regular network leads to higher values of the\ntotal liquid uptake and the invasive capacity (A-particles in B-side and\nviceversa than in the disordered network, though differences vanish in the\nlimit of rigid interfaces. Uptake and invasion are optimized at a cross-linking\ndegree that depends on the interfacial strength, tending to 15 - 20% for\nmoderate and stiff interfaces. As the interfacial strength increases, the\nmiscibility inside the nanogel is enhanced by a factor of up to 5 with respect\nto the bare interface, with the disordered networks providing a better mixing\nthan their ideal counterparts. The emerging scenario reported here provides\ngeneral guidelines for tuning the shape, uptake, invasive, and mixing\ncapacities of nanogels adsorbed at liquid-liquid interfaces.",
        "positive": "2D colloidal condensation driven by substrate elasticity: This paper has been withdrawn by the authors."
    },
    {
        "anchor": "Agglomeration and filtration of colloidal suspensions with DVLO\n  interactions in simulation and experiment: Cake filtration is a widely used solid-liquid separation process. However,\nthe high flow resistance of the nanoporous filter cake lowers the efficiency of\nthe process significantly. The structure and thus the permeability of the\nfilter cakes depend on the compressive load acting on the particles, the\nparticles size, and the agglomeration of the particles. The latter is\ndetermined by the particle charge and the ionic strength of the suspension, as\ndescribed by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. In this paper,\nwe propose a combined stochastic rotation dynamics (SRD) and molecular dynamics\n(MD) methodology to simulate the cake formation. The simulations give further\ninsight into the dependency of the filter cakes' structure on the agglomeration\nof the particles, which cannot be accessed experimentally. The permeability, as\ninvestigated with lattice Boltzmann (LB) simulations of flow through the\ndiscretized cake, depends on the particle size and porosity, and thus on the\nagglomeration of the particles. Our results agree qualitatively with\nexperimental data obtained from colloidal boehmite suspensions.",
        "positive": "Cellular Micromasonry: Biofabrication with Single Cell Precision: In many tissues, cell type varies over single-cell length-scales, creating\ndetailed spatial heterogeneities fundamental to physiological function. To gain\nunderstanding of this relationship between tissue function and detailed\nstructure, and to one day engineer structurally and physiologically accurate\ntissues, we need the ability to assemble 3D cellular structures having the\nlevel of detail found in living tissue. Here we introduce a method of 3D cell\nassembly that has a level of precision finer than the single-cell scale. With\nthis method we create numerous structures having well-defined spatial patterns,\ndemonstrating that cell type can be varied over the scale of individual cells\nand showing function after their assembly. This technique provides innumerable\nopportunities to study cellular behavior in defined contexts including complex\ninteractions operating during embryogenesis."
    },
    {
        "anchor": "Liquid crystal phase and waterlike anomalies in a core-softened\n  shoulder-dumbbells system: Using molecular dynamics we investigate the thermodynamics, dynamics and\nstructure of 250 diatomic molecules interacting by a core-softened potential.\nThis system exhibits thermodynamics, dynamics and structural anomalies: a\nmaximum in density-temperature plane at constante pressure and maximum and\nminimum points in the diffusivity and translational order parameter against\ndensity at constant temperature. Starting with very dense systems and\ndecreasing density the mobility at low temperatures first increases, reach a\nmaximum, then decreases, reach a minimum and finally increases. In the\npressure-temperature phase diagram the line of maximum translational order\nparameter is located outside the line of diffusivity extrema that is enclosing\nthe temperature of maximum density line. We compare our results with the\nmonomeric system showing that the anisotropy due to the dumbbell leads to a\nmuch larger solid phase and to the appearance of a liquid crystal phase. the\ndouble ranged thermodynamic and dynamic anomalies.",
        "positive": "Polarity Free Magnetic Repulsion and Magnetic Bound State: This is a report on a dynamic autonomous magnetic interaction which does not\ndepend on polarities resulting in short ranged repulsion involving one or more\ninertial bodies and a new class of bound state based on this interaction. Both\neffects are new to the literature, found so far. Experimental results are\ngeneralized and reported qualitatively. Working principles of these effects are\nprovided within classical mechanics and found consistent with observations and\nsimulations. The effects are based on the interaction of a rigid and finite\ninertial body (an object having mass and moment of inertia) endowed with a\nmagnetic moment with a cyclic inhomogeneous magnetic field which does not\nrequire to have a local minimum. Such a body having some degrees of freedom\ninvolved in driven harmonic motion by this interaction can experience a net\nforce in the direction of the weak field regardless of its position and\norientation or can find stable equilibrium with the field itself autonomously.\nThe former is called polarity free magnetic repulsion and the latter magnetic\nbound state. Experiments show that a bound state can be obtained between two\nfree bodies having magnetic dipole moment. Various schemes of trapping bodies\nhaving magnetic moments by rotating fields are realized as well as rotating\nbodies trapped by a static dipole field in presence of gravity. Also, a special\ncase of bound state called bipolar bound state between free dipole bodies is\ninvestigated."
    },
    {
        "anchor": "Interactions between Polymers and Nanoparticles : Formation of\n  Supermicellar Hybrid Aggregates: When polyelectrolyte-neutral block copolymers are mixed in solutions to\noppositely charged species (e.g. surfactant micelles, macromolecules, proteins\netc), there is the formation of stable supermicellar aggregates combining both\ncomponents. The resulting colloidal complexes exhibit a core-shell structure\nand the mechanism yielding to their formation is electrostatic self-assembly.\nIn this contribution, we report on the structural properties of supermicellar\naggregates made from yttrium-based inorganic nanoparticles (radius 2 nm) and\npolyelectrolyte-neutral block copolymers in aqueous solutions. The yttrium\nhydroxyacetate particles were chosen as a model system for inorganic colloids,\nand also for their use in industrial applications as precursors for ceramic and\nopto-electronic materials. The copolymers placed under scrutiny are the water\nsoluble and asymmetric poly(sodium acrylate)poly(acrylamide) diblocks. Using\nstatic and dynamical light scattering experiments, we demonstrate the analogy\nbetween surfactant micelles and nanoparticles in the complexation phenomenon\nwith oppositely charged polymers. We also determine the sizes and the\naggregation numbers of the hybrid organic-inorganic complexes. Several\nadditional properties are discussed, such as the remarkable stability of the\nhybrid aggregates and the dependence of their sizes on the mixing conditions.",
        "positive": "Statistical Properties of Autonomous Flows in 2D Active Nematics: We study the dynamics of a tunable 2D active nematic liquid crystal composed\nof microtubules and kinesin motors confined to an oil-water interface. Kinesin\nmotors continuously inject mechanical energy into the system through ATP\nhydrolysis, powering the relative microscopic sliding of adjacent microtubules,\nwhich in turn generates macroscale autonomous flows and chaotic dynamics. We\nuse particle image velocimetry to quantify two-dimensional flows of active\nnematics and extract their statistical properties. In agreement with the\nhydrodynamic theory, we find that the vortex areas comprising the chaotic flows\nare exponentially distributed, which allows us to extract the characteristic\nsystem length scale. We probe the dependence of this length scale on the ATP\nconcentration, which is the experimental knob that tunes the magnitude of the\nactive stress. Our data suggest a possible mapping between the ATP\nconcentration and the active stress that is based on the Michaelis-Menten\nkinetics that governs motion of individual kinesin motors."
    },
    {
        "anchor": "Giant fluctuations at a granular phase separation threshold: We investigate a phase separation instability that occurs in a system of\nnearly elastically colliding hard spheres driven by a thermal wall. If the\naspect ratio of the confining box exceeds a threshold value, granular\nhydrostatics predict phase separation: the formation of a high-density region\ncoexisting with a low-density region along the wall that is opposite to the\nthermal wall. Event-driven molecular dynamic simulations confirm this\nprediction. The theoretical bifurcation curve agrees with the simulations\nquantitatively well below and well above the threshold. However, in a wide\nregion of aspect ratios around the threshold, the system is dominated by\nfluctuations, and the hydrostatic theory breaks down. Two possible scenarios of\nthe origin of the giant fluctuations are discussed.",
        "positive": "Electrosorption-induced deformation of a porous electrode with\n  non-convex pore geometry in electrolyte solutions: a theoretical study: Porous carbon is well known as a good candidate for the development of\nelectrochemical double-layer capacitors. Predominantly, many conventional\ncarbons are microporous and often well described by the assumption of slit pore\ngeometry. However, there is a class of carbons that is significantly different\nfrom the others, namely templated mesoporous carbons. In this work, we study\nelectrosorption-induced deformation in CMK-3-like mesopores having nonconvex\ngeometry applying a mean-field approach. The model is based on the modified\nPoisson-Boltzmann equation taking into account the excluded volume of the ions\nwithin the hard-sphere model in the Percus-Yevick approximation. We assume that\nthe deformation is caused by two effects: ion osmotic pressure and\nelectrostatic interactions of the electric double layers on charged rods. The\nlatter were calculated via the Maxwell stress tensor agreeing with the modified\nPoisson-Boltzmann equation. We estimated the pore-load modulus of the\nCMK-3-like material and found an agreement with the previously obtained values\nby small-angle neutron scattering (SANS). Additionally, we studied the\ndifferential capacitance in the non-convex pore geometry and found that the\nbehavior of the differential capacitance profiles was similar to that of the\nprofiles obtained for flat electric double layers. Namely, we obtained the\ncrowding regime at rather high voltages and more pronounced profile asymmetry\nwith increasing differences in the ionic sizes."
    },
    {
        "anchor": "Three Comments on \"A Simple Incremental Modelling of Granular-Media\n  Mechanics\": Using the recent incremental modelling, it is shown that the trajectory of a\nsample in the phase space of soil mechanics in the vicinity of the critical\nstate is not governed by the rigidity matrix, but by its variations. The\ncharacteristics are used to predict that pseudo Young modulus tends to 0 as B\n-M-1 tends to 0, i.e. near the critical point, where B is the\nvertical-to-lateral-stress ratio during an axi-symmetric test. An attempt to\nunderstand and predict unstable behaviours is done using the same modelling.\nCompatibility of this modelling with results on soil liquefaction is\nemphasised.",
        "positive": "Simulating wet active polymers by multiparticle collision dynamics: The conformational and dynamical properties of active Brownian polymers\nembedded in a fluid depend on the nature of the driving mechanism, e.g.,\nself-propulsion or external actuation of the monomers. Implementations of\nself-propelled and actuated active Brownian polymers in a multiparticle\ncollision dynamics (MPC) fluid are presented, which capture the distinct\ndifferences between the two driving mechanisms. The active force-free nature of\nself-propelled monomers requires adaptations of the MPC simulation scheme, with\nits streaming and collision steps, where the monomer self-propulsion velocity\nhas to be omitted in the collision step. Comparison of MPC simulation results\nfor active polymers in dilute solution with results of Brownian dynamics\nsimulations accounting for hydrodynamics via the Rotne-Prager-Yamakawa tensor\nconfirm the suitability of the implementation. The polymer conformational and\ndynamical properties are analyzed by the static and dynamic structure factor,\nand the scaling behavior of the latter with respect to the wave-number and time\ndependence are discussed. The dynamic structure factor displays various\nactivity-induced temporal regimes, depending on the considered wave number,\nwhich reflect the persistent diffusive motion of the whole polymer at small\nwave numbers, and the activity-enhanced internal dynamics at large wave\nnumbers. The obtained simulation results are compared with theoretical\npredictions."
    },
    {
        "anchor": "Impact of Side Chain Hydrophilicity on Packing, Swelling and Ion\n  Interactions in Oxy-bithiophene Semiconductors: Exchanging hydrophobic alkyl-based side chains to hydrophilic glycol-based\nside chains is a widely adopted method for improving mixed-transport device\nperformance, despite the impact on solid state packing and polymer-electrolyte\ninteractions being poorly understood. Presented here is a Molecular Dynamics\n(MD) force field for modelling alkoxylated and glycolated polythiophenes. The\nforce field is validated against known packing motifs for their monomer\ncrystals. MD simulations, coupled with X-ray Diffraction (XRD), show that\nalkoxylated polythiophenes will pack with a `tilted stack' and straight\ninterdigitating side chains, whilst their glycolated counterpart will pack with\na `deflected stack' and an s-bend side chain configuration. MD simulations\nreveal water penetration pathways into the alkoxylated and glycolated crystals\n- through the {\\pi}-stack and through the lamellar stack respectively. Finally,\nthe two distinct ways tri-ethylene glycol polymers can bind to cations are\nrevealed, showing the formation of a meta-stable single bound state, or an\nenergetically deep double bound state, both with a strong side chain length\ndependance. The minimum energy pathways for the formation of the chelates are\nidentified, showing the physical process through which cations can bind to one\nor two side chains of a glycolated polythiophene, with consequences for ion\ntransport in bithiophene semiconductors.",
        "positive": "Collective behavior of colloids due to critical Casimir interactions: If colloidal solute particles are suspended in a solvent close to its\ncritical point, they act as cavities in a fluctuating medium and thereby\nrestrict and modify the fluctuation spectrum in a way which depends on their\nrelative configuration. As a result effective, so-called critical Casimir\nforces (CCFs) emerge between the colloids. The range and the amplitude of CCFs\ndepend sensitively on the temperature and the composition of the solvent as\nwell as on the boundary conditions of the order parameter of the solvent at the\nparticle surfaces. These remarkable, moreover universal features of the CCFs\nprovide the possibility for an active control over the assembly of colloids.\nThis has triggered a recent surge of experimental and theoretical interest in\nthese phenomena. We present an overview of current research activities in this\narea. Various experiments demonstrate the occurrence of thermally reversible\nself-assembly or aggregation or even equilibrium phase transitions of colloids\nin the mixed phase below the lower consolute points of binary solvents. We\ndiscuss the status of the theoretical description of these phenomena, in\nparticular the validity of a description in terms of effective, one-component\ncolloidal systems and the necessity of a full treatment of a ternary\nsolvent-colloid mixture. We suggest perspectives on the directions towards\nwhich future research in this field might develop."
    },
    {
        "anchor": "Metastable states as a key to the dynamics of supercooled liquids: Computer simulations of a model glass-forming system are presented, which are\nparticularly sensitive to the correlation between the dynamics and the\ntopography of the potential energy landscape. This analysis clearly reveals\nthat in the supercooled regime the dynamics is strongly influenced by the\npresence of deep valleys in the energy landscape, corresponding to long-lived\nmetastable amorphous states. We explicitly relate non-exponential relaxation\neffects and dynamic heterogeneities to these metastable states and thus to the\nspecific topography of the energy landscape.",
        "positive": "Polymer-Nanoparticle Complexes : from Dilute Solution to Solid State: We report on the formation and the structural properties of supermicellar\naggregates also called electrostatic complexes, made from mineral nanoparticles\nand polyelectrolyte-neutral block copolymers in aqueous solutions. The mineral\nparticles put under scrutiny are ultra-fine and positively charged yttrium\nhydroxyacetate nanoparticles. Combining light, neutron and x-ray scattering\nexperiments, we have characterized the sizes and the aggregation numbers of the\norganic-inorganic complexes. We have found that the hybrid aggregates have\ntypical sizes in the range 100 nm and exhibit a remarkable colloidal stability\nwith respect to ionic strength and concentration variations. Solid films with\nthicknesses up to several hundreds of micrometers were cast from solutions,\nresulting in a bulk polymer matrix in which nanoparticle clusters are dispersed\nand immobilized. It was found in addition that the structure of the complexes\nremains practically unchanged during film casting."
    },
    {
        "anchor": "Universal scaling of the diffusivity of dendrimers in a semidilute\n  solution of linear polymers: The static and dynamic properties of dendrimers in semidilute solutions of\nlinear chains of comparable size are investigated using Brownian dynamics\nsimulations. The radius of gyration and diffusivity of a wide variety of low\ngeneration dendrimers and linear chains in solution follow universal scaling\nlaws independent of their topology. Analysis of the shape functions and\ninternal density of dendrimers shows that they are more spherical than linear\nchains and have a dense core. At intermediate times, dendrimers become\nsubdiffusive, with an exponent higher than that previously reported for\nnanoparticles in semidilute polymer solutions. The long-time diffusivity of\ndendrimers does not follow theoretical predictions for nanoparticles. We\npropose a new scaling law for the long-time diffusion coefficients of\ndendrimers which accounts for the fact that, unlike nanoparticles, dendrimers\nshrink with an increase in background solution concentration. Analysis of the\nproperties of a special case of a higher functionality dendrimer shows a\ntransition from polymer-like to nanoparticle-like behaviour.",
        "positive": "Dynamics of a tracer granular particle as a non-equilibrium Markov\n  process: The dynamics of a tracer particle in a stationary driven granular gas is\ninvestigated. We show how to transform the linear Boltzmann equation describing\nthe dynamics of the tracer into a master equation for a continuous Markov\nprocess. The transition rates depend upon the stationary velocity distribution\nof the gas. When the gas has a Gaussian velocity probability distribution\nfunction (pdf), the stationary velocity pdf of the tracer is Gaussian with a\nlower temperature and satisfies detailed balance for any value of the\nrestitution coefficient $\\alpha$. As soon as the velocity pdf of the gas\ndeparts from the Gaussian form, detailed balance is violated. This\nnon-equilibrium state can be characterized in terms of a Lebowitz-Spohn action\nfunctional $W(\\tau)$ defined over trajectories of time duration $\\tau$. We\ndiscuss the properties of this functional and of a similar functional\n$\\bar{W}(\\tau)$ which differs from the first for a term which is non-extensive\nin time. On the one hand we show that in numerical experiments, i.e. at finite\ntimes $\\tau$, the two functionals have different fluctuations and $\\bar{W}$\nalways satisfies an Evans-Searles-like symmetry. On the other hand we cannot\nobserve the verification of the Lebowitz-Spohn-Gallavotti-Cohen (LS-GC)\nrelation, which is expected for $W(\\tau)$ at very large times $\\tau$. We give\nan argument for the possible failure of the LS-GC relation in this situation.\nWe also suggest practical recipes for measuring $W(\\tau)$ and $\\bar{W}(\\tau)$\nin experiments."
    },
    {
        "anchor": "Minimal Bending Energies of Bilayer Polyhedra: Motivated by recent experiments on bilayer polyhedra composed of amphiphilic\nmolecules, we study the elastic bending energies of bilayer vesicles forming\npolyhedral shapes. Allowing for segregation of excess amphiphiles along the\nridges of polyhedra, we find that bilayer polyhedra can indeed have lower\nbending energies than spherical bilayer vesicles. However, our analysis also\nimplies that, contrary to what has been suggested on the basis of experiments,\nthe snub dodecahedron, rather than the icosahedron, generally represents the\nenergetically favorable shape of bilayer polyhedra.",
        "positive": "Pattern formation of microtubules and motors: inelastic interaction of\n  polar rods: We derive a model describing spatio-temporal organization of an array of\nmicrotubules interacting via molecular motors. Starting from a stochastic model\nof inelastic polar rods with a generic anisotropic interaction kernel we obtain\na set of equations for the local rods concentration and orientation. At large\nenough mean density of rods and concentration of motors, the model describes\norientational instability. We demonstrate that the orientational instability\nleads to the formation of vortices and (for large density and/or kernel\nanisotropy) asters seen in recent experiments."
    },
    {
        "anchor": "Reaction-diffusion with stochastic decay rates: Understanding anomalous transport and reaction kinetics due to microscopic\nphysical and chemical disorder is a long-standing goal in many fields including\ngeophysics, biology, and engineering. We consider reaction-diffusion\ncharacterized by fluctuations in both transitions times and decay rates. We\nintroduce and analyze a model framework that explicitly connects microscopic\nfluctuations with the mescoscopic description. For broad distributions of\ntransport and reaction time scales we compute the particle density and derive\nthe equations governing its evolution, finding power-law decay of the survival\nprobability, and spatially heterogeneous decay that leads to subdiffusion and\nan asymptotically stationary surviving-particle density. These anomalies are\nclearly attributable to non-Markovian effects that couple transport and\nchemical properties in both reaction and diffusion terms.",
        "positive": "Intrusion of liquids into liquid infused surfaces with nanoscale\n  roughness: We present a theoretical study of the intrusion of an ambient liquid into\npores of a nano-corrugated wall w. The pores are prefilled with a liquid\nlubricant which adheres to the walls of the pores more strongly than the\nambient liquid. The two liquids are modeled as a binary mixture of two types of\nparticles, A and B. The mixture can decompose into an A-rich(ambient) liquid,\nand a B-rich(lubricant) liquid. The wall attracts B particles more strongly\nthan A particles. The ratio of w-A to w-B interaction strengths is changed to\ntune the contact angle ${\\theta}_{AB}$ formed by the A-rich/B-rich liquid\ninterface between the two fluids and the corresponding planar wall. We use\nclassical density functional theory, in order to capture the effects of\nmicroscopic details on the intrusion transition as a function of composition\nand pressure of the ambient liquid, for various values of ${\\theta}_{AB}$ and\ndifferent pit sizes.\n  We also studied the reverse process in which a pore initially filled with the\nambient liquid is refilled with the lubricant. For small ${\\theta}_{AB}$ ,there\nis no hysteresis. However, beyond a certain ${\\theta}_{AB}$, we find the\npresence of hysteresis, which increases with increasing ${\\theta}_{AB}$. The\ndependence of location of the intrusion on ${\\theta}_{AB}$ and on the pit size,\nqualitatively follows the corresponding shift of the capillary-coexistence line\naway from the bulk liquid-liquid coexistence line, as predicted by a\nmacroscopic capillarity model. The quantitative discrepancies become larger for\nnarrower cavities. For the considered geometry, macroscopic capillarity theory\npredicts an open hysteresis loop above a threshold value of ${\\theta}_{AB} =\n54.7^\\circ$. This threshold, however, shifts to much higher values if widths of\nthe pores become smaller than roughly ten times the diameter of the fluid\nparticles."
    },
    {
        "anchor": "A robust method for quantification of surface elasticity in soft solids: We propose an approach to measure surface elastic constants of soft solids.\nGenerally, this requires one to probe interfacial mechanics at around the\nelastocapillary length scale, which is typically microscopic. Deformations of\nmicroscopic droplets embedded in soft solids are particularly attractive,\nbecause they avoid intrinsic nonlinearities associated with previous\nexperiments such as the equilibrium of contact lines and the relaxation of\npatterned surfaces. We derive analytical solutions for the shape of droplets\nunder uniaxial deformation and for the radius of droplets upon hydrostatic\ninflation. We couple mechanical deformations to the dissolution of droplets to\nassess experimental sensitivities. Combined with experimental data from both\nmodes of deformation, one should be able to reliably extract the complete set\nof isotropic surface material parameters following a specific minimization\nprocedure.",
        "positive": "Microscale fluid flow induced by thermoviscous expansion along a\n  traveling wave: The thermal expansion of a fluid combined with a temperature-dependent\nviscosity introduces nonlinearities in the Navier-Stokes equations unrelated to\nthe convective momentum current. The couplings generate the possibility for net\nfluid flow at the microscale controlled by external heating. This novel\nthermo-mechanical effect is investigated for a thin fluid chamber by a\nnumerical solution of the Navier-Stokes equations and analytically by a\nperturbation expansion. A demonstration experiment confirms the basic mechanism\nand quantitatively validates our theoretical analysis."
    },
    {
        "anchor": "Ring-o-rings: a new category of supramolecular structures with\n  topologically tunable properties: Macrochains of topologically interlocked rings with unique physical\nproperties have recently gained considerable interest in supramolecular\nchemistry, biology, and soft matter. Most of the work has been, so far, focused\non linear chains and on their variety of conformational properties compared to\nstandard polymers. Here we go beyond the linear case and show that, by\ncircularizing such macrochains, one can exploit the topology of the local\ninterlockings to store torsional stress in the system, altering significantly\nits metric and local properties. Moreover, by properly defining the twist (Tw)\nand writhe (Wr) of these macrorings we show the validity of a relation\nequivalent to the C\\v{a}lug\\v{a}reanu-White-Fuller theorem $Tw + Wr$=const,\noriginally proved for ribbon like structures such as ds-DNA. Our results\nsuggest that circular structures of topologically linked rings with storable\nand tunable torsion can form a new category of highly designable multiscale\nstructures with potential applications in supramolecular chemistry and material\nscience",
        "positive": "Conformational properties of compact polymers: Monte Carlo simulations of coarse-grained polymers provide a useful tool to\ndeepen the understanding of conformational and statistical properties of\npolymers both in physical as well as in biological systems. In this study we\nsample compact conformations on a cubic LxLxL lattice with different occupancy\nfractions by modifying a recently proposed algorithm. The system sizes studied\nextend up to N=256000 monomers, going well beyond the limits of older\npublications on compact polymers. We analyze several conformational properties\nof these polymers, including segment correlations and screening of excluded\nvolume. Most importantly we propose a scaling law for the end-to-end distance\ndistribution and analyze the moments of this distribution. It shows\nuniversality with respect to different occupancy fractions, i.e. system\ndensities. We further analyze the distance distribution between intrachain\nsegments, which turns out to be of great importance for biological experiments.\nWe apply these new findings to the problem of chromatin folding inside\ninterphase nuclei and show that -- although chromatin is in a compacted state\n-- the classical theory of compact polymers does not explain recent\nexperimental results."
    },
    {
        "anchor": "Optimization-based design and analysis of tailor-made ionic liquids: Solvents comprise two thirds of all industrial emissions. Traditional organic\nsolvents easily reach the atmosphere as they have high vapor pressure and are\nlinked to a host of negative environmental effects including climate change,\nurban air-quality and human illness. Room temperature ionic liquids (RTIL), on\nthe other hand, have low vapor pressure and are not flammable or explosive,\nthereby resulting in fewer environmental burdens and health hazards. However,\ntheir life cycle environmental impacts as well as freshwater ecotoxicity\nimplications are poorly understood. RTILs are molten salts that exist as\nliquids at relatively low temperatures and have unique properties. Ionic\nliquids consist of a large organic cation and charge-delocalized inorganic or\norganic anion of smaller size and asymmetric shape. The organic cation can\nundergo unlimited structural variations through modification of the alkyl\ngroups attached to the side chain of the base cation skeleton and most of these\nstructural variations are feasible, from chemical synthesis point of view, due\nto the easy nature of preparation of their components. Functionally, ionic\nliquids can be tuned to impart specific desired properties by switching\nanions/cations or by incorporating functionalities into the cations/anions. It\nis estimated that theoretically more than a trillion ionic liquid structures\ncan be formed. Due to their tunable nature, these molten salts have the\npotential to be used as solvents for variety of applications.",
        "positive": "Elastohydrodynamic synchronization of rotating bacterial flagella: To rotate continuously without jamming, the flagellar filaments of bacteria\nneed to be locked in phase. While several models have been proposed for\neukaryotic flagella, the synchronization of bacterial flagella is less well\nunderstood. Starting from a reduced model of flexible and\nhydrodynamically-coupled bacterial flagella, we rigorously coarse-grain the\nequations of motion using the method of multiple scales, and hence show that\nbacterial flagella generically synchronize to zero phase difference via an\nelastohydrodynamic mechanism. Remarkably, the far-field rate of synchronization\nis maximized at an intermediate value of elastic compliance, with surprising\nimplications for bacteria."
    },
    {
        "anchor": "Convenient analytical formula for cluster mean diameter and diameter\n  dispersion after nucleation burst: We propose a new method of estimating the mean diameter and dispersion of\nclusters formed in a cooling gas, right after the nucleation stage. Using a\nmoment model developed by Friedlander [S.K. Friedlander, Ann. N.Y. Acad. Sci.\n354 (1983)], we derive an analytic relationship for both cluster diameter and\ndiameter dispersion as a function of two of the characteristic times of the\nsystem - the cooling time and primary constituents collision time. These\nformulas can be used to predict diameter and dispersion variation with process\nparameters such as the initial monomer pressure or cooling rate. It is also\npossible to use them as an input to the coagulation stage, without the need to\ncompute complex cluster generation during the nucleation burst. We compared our\nresults with a nodal code and got excellent agreement.",
        "positive": "Capillary micromechanics: Measuring the elasticity of microscopic soft\n  objects: We present a simple method for accessing the elastic properties of\nmicroscopic deformable particles. This method is based on measuring the\npressure-induced deformation of soft particles as they are forced through a\ntapered glass microcapillary. It allows us to determine both the compressive\nand the shear modulus of a deformable object in one single experiment.\nMeasurements on a model system of poly-acrylamide microgel particles exhibit\nexcellent agreement with measurements on bulk gels of identical composition.\nOur approach is applicable over a wide range of mechanical properties and\nshould thus be a valuable tool for the characterization of a variety of soft\nand biological materials."
    },
    {
        "anchor": "MD Simulations of Charged Binary Mixtures Reveal a Generic Relation\n  Between High- and Low-Temperature Behavior: Experimental studies of the glassy slowdown in molecular liquids indicate\nthat the high-temperature activation energy $E_{\\infty}$ of glass-forming\nliquids is directly related to their glass transition temperature\n$T_{\\text{g}}$. To further investigate such a possible relation between high-\nand low-temperature dynamics in glass-forming liquids, we analyze the glassy\ndynamics of binary mixtures using molecular dynamics (MD) simulations. We\nconsider a binary mixture of charged Lennard-Jones particles and vary the\npartial charges of the particles, and thus, the high-temperature activation\nenergy and the glass transition temperature of the system. Based on previous\nresults, we introduce a phenomenological model describing relaxation times over\nthe whole temperature regime from high temperatures to temperatures well inside\nthe supercooled regime. By investigating the dynamics of both particle species\non molecular and diffusive length scales along isochoric and isobaric pathways,\nwe find a quadratic charge dependence of both $E_{\\infty}$ and $T_{\\text{g}}$,\nresulting in an approximately constant ratio of both quantities independent of\nthe underlying observable, the thermodynamic ensemble, and the particle\nspecies, and this result is robust against the actual definition of\n$T_{\\text{g}}$. This generic relation between the activation energy and the\nglass transition temperature indicates that high-temperature dynamics and the\nglassy slowdown are related phenomena, and the knowledge of $E_{\\infty}$ may\nallow to approximately predict $T_{\\text{g}}$.",
        "positive": "Asymptotic reductions of the diffuse-interface model, with applications\n  to contact lines in fluids: The diffuse-interface model (DIM) is a tool for studying interfacial\ndynamics. In particular, it is used for modeling contact lines, i.e., curves\nwhere a liquid, gas, and solid are in simultaneous contact. As well as all\nother models of contact lines, the DIM implies an additional assumption: that\nthe flow near the liquid/gas interface is isothermal. In this work, this\nassumption is checked for the four fluids for which all common models of\ncontact lines fail. It is shown that, for two of these fluids (including\nwater), the assumption of isothermality does not hold."
    },
    {
        "anchor": "Swelling, Structure, and Phase Stability of Compressible Microgels: Microgels are soft colloidal particles that, when dispersed in a solvent,\nswell and deswell in response to changes in environmental conditions, such as\ntemperature, concentration, and $p$H. Using Monte Carlo simulation, we model\nbulk suspensions of microgels that interact via Hertzian elastic interparticle\nforces and can expand or contract via trial moves that allow particles to\nchange size in accordance with the Flory-Rehner free energy of cross-linked\npolymer gels. We monitor the influence of particle compressibility, size\nfluctuations, and concentration on bulk structural and thermal properties by\ncomputing particle swelling ratios, radial distribution functions, static\nstructure factors, osmotic pressures, and freezing densities. For microgels in\nthe nanoscale size range, particle compressibility and associated size\nfluctuations suppress crystallization, shifting the freezing transition to a\nhigher density than for the hard-sphere fluid. As densities increase beyond\nclose packing, microgels progressively deswell, while their intrinsic size\ndistribution grows increasingly polydisperse.",
        "positive": "Active translocation of a semiflexible polymer assisted by an ATP-based\n  molecular motor: In this work we study the assisted translocation of a polymer across a\nmembrane nanopore, inside which a molecular motor exerts a force fuelled by the\nhydrolysis of ATP molecules. In our model the motor switches to its active\nstate for a fixed amount of time, while it waits for an ATP molecule binding\nand triggering the impulse, during an exponentially distributed time lapse. The\npolymer is modelled as a beads-springs chain with both excluded volume and\nbending contributions, and moves in a stochastic three dimensional environment\nmodelled with a Langevin dynamics at fixed temperature. The resulting dynamics\nshows a Michaelis-Menten translocation velocity that depends on the chain\nflexibility. The scaling behavior of the mean translocation time with the\npolymer length for different bending values is also investigated."
    },
    {
        "anchor": "3D Fluorescent Mapping of Invisible Molecular Damage after Cavi-tation\n  in Hydrogen Exposed Elastomers: Elastomers saturated with gas at high pressure suffer from cavity nucleation,\ninflation, and deflation upon rapid or explosive de-compression. Although this\nprocess often results in undetectable changes in appearance, it causes internal\ndamage, hampers func-tionality (e.g., permeability), and shortens lifetime.\nHere, we tag a model poly(ethyl acrylate) elastomer with {\\pi}-extended\nanthracene-maleimide adducts that fluoresce upon polymer chain scission, and\nmap in 3D the internal damage present after a cycle of gas satu-ration and\nrapid decompression. Interestingly, we observe that each cavity observable\nduring the decompression results in a dam-aged region, the shape of which\nreveals a fracture locus of randomly oriented penny-shape cracks (i.e., with a\nflower-like morpholo-gy) that contain crack arrest lines. Thus, cavity growth\nlikely proceeds discontinuously (i.e., non-steadily) through the stable and\nunstable fracture of numerous 2D crack planes. This non-destructive methodology\nto visualize in 3D molecular damage in polymer networks is novel and serves to\nunderstand how fracture occurs under complex 3D loads, predict mechanical aging\nof pristine look-ing elastomers, and holds potential to optimize\ncavitation-resistant materials.",
        "positive": "Systematic time-scale-bridging molecular dynamics applied to flowing\n  polymer melts: We present a novel thermodynamically guided, low-noise, time-scale bridging,\nand pertinently efficient strategy for the dynamic simulation of microscopic\nmodels for complex fluids. The systematic coarse-graining method is exemplified\nfor low-molecular polymeric systems subjected to homogeneous flow fields. We\nuse established concepts of nonequilibrium thermodynamics and an alternating\nMonte-Carlo--molecular dynamics iteration scheme in order to obtain the model\nequations for the slow variables. For chosen flow situations of interest, the\nestablished model predicts structural as well as material functions beyond the\nregime of linear response. As a by-product, we present the first steady state\nequibiaxial simulation results for polymer melts. The method is simple to\nimplement and allows for the calculation of time-dependent behavior through\nquantities readily available from the nonequilibrium steady states."
    },
    {
        "anchor": "A new relation between pressure and fractional flow in two-phase flow in\n  porous media: We study average flow properties in porous media using a two-dimensional\nnetwork simulator. It models the dynamics of two-phase immiscible bulk flow\nwhere film flow can be neglected. The boundary conditions are biperiodic which\nprovide a means of studying steady state flow where complex bubble dynamics\ndominate the flow picture. We find fractional flow curves and corresponding\npressure curves for different capillary numbers. In particular, we study the\ncase of the two phases having equal viscosity. In this case we find that the\nderivative of the fractional flow with respect to saturation is related to the\nglobal pressure drop. This result can also be expressed in terms of relative\npermeabilities or mobilities, resulting in an equation tying together the\nmobilities of the two phases.",
        "positive": "Chiral active matter in external potentials: We investigate the interplay between chirality and confinement induced by the\npresence of an external potential. For potentials having radial symmetry, the\ncircular character of the trajectories induced by the chiral motion reduces the\nspatial fluctuations of the particle, thus providing an extra effective\nconfining mechanism, that can be interpreted as a lowering of the effective\ntemperature. In the case of non-radial potentials, for instance, with an\nelliptic shape, chirality displays a richer scenario. Indeed, the chirality can\nbreak the parity symmetry of the potential that is always fullfilled in the\nnon-chiral system. The probability distribution displays a strong\nnon-Maxwell-Boltzmann shape that emerges in cross-correlations between the two\nCartesian components of the position, that vanishes in the absence of chirality\nor when radial symmetry of the potential is restored. These results are\nobtained by considering two popular models in active matter, i.e. chiral Active\nBrownian particles and chiral active Ornstein-Uhlenbeck particles."
    },
    {
        "anchor": "Phase Separation and Self-Assembly in a Fluid of Mickey Mouse Particles: Recent developments in the synthesis of colloidal particles allow for control\nover shape and inter-particle interaction. One example, among others, is the\nso-called \"Mickey Mouse\" (MM) particle for which the self-assembly properties\nhave been previously studied yielding a stable cluster phase together with\nelongated, tube-like structures. Here, we investigate under which conditions a\nfluid of Mickey Mouse particles can yield phase separation and how the\nself-assembly behaviour affects the gas-liquid coexistence. We vary the\ndistance between the repulsive and the attractive lobes (bond length), and the\ninteraction range, and follow the evolution of the gas-liquid (GL) coexistence\ncurve. We find that upon increasing the bond length distance the binodal line\nshifts to lower temperatures, and that the interaction range controls the\ntransition between phase separation and self-assembly of clusters. Upon further\nreduction of the interaction range and temperature, the clusters assume an\nincreasingly ordered tube-like shape, ultimately matching the one previously\nreported in literature. These results are of interest when designing particle\nshape and particle-particle interaction for self-assembly processes.",
        "positive": "Angular Independent Photonic Pigments via the Controlled Micellization\n  of Amphiphilic Bottlebrush Block Copolymers: Photonic materials with angular independent structural colour are highly\ndesirable because they offer the broad viewing angles required for application\nas colorants in paints, cosmetics, textiles or displays. However, they are\nchallenging to fabricate as they require isotropic nanoscale architectures with\nonly short-range correlation. In this article, porous microparticles with such\na structure are produced in a single, scalable step from an amphiphilic\nbottlebrush block copolymer. This is achieved by exploiting a novel controlled\nmicellization self-assembly mechanism within emulsified toluene-in-water\ndroplets. By restricting water permeation through the droplet interface, the\nsize of the pores can be precisely addressed, resulting in structurally\ncoloured pigments. Furthermore, the reflected colour can be tuned to reflect\nacross the full visible spectrum using only a single polymer (Mn = 290 kDa) by\naltering the initial emulsification conditions. Such photonic pigments have\nseveral key advantages over their crystalline analogues, as they provide\nisotropic structural coloration that suppresses iridescence and improves colour\npurity without the need for either refractive index matching or the inclusion\nof a broadband absorber."
    },
    {
        "anchor": "Elastic Convection in Vibrated Viscoplastic Fluids: We observe a new type of behavior in a shear thinning yield stress fluid:\nfreestanding convection rolls driven by vertical oscillation. The convection\noccurs without the constraint of container boundaries yet the diameter of the\nrolls is spontaneously selected for a wide range of parameters. The transition\nto the convecting state occurs without hysteresis when the amplitude of the\nplate acceleration exceeds a critical value. We find that a non-dimensional\nstress, the stress due to the inertia of the fluid normalized by the yield\nstress, governs the onset of the convective motion.",
        "positive": "The central role of thermal collective strain in the relaxation of\n  structure in a supercooled liquid: The spatial distribution of structural relaxation in a supercooled liquid is\nstudied using molecular dynamics simulations of a 2D binary mixture. It is\nshown that the spatial heterogeneity of the relaxation along with the time\nscale of the relaxation is determined, not by the frequency with which\nparticles move a distance pi/2kBragg, but by the frequency with which particles\ncan achieve persistent displacements. We show that these persistent\ndisplacements are achieved through the coupled action of local reorganizations\nand unrecoverable thermal strains."
    },
    {
        "anchor": "Entanglement reduction induced by geometrical confinement in polymer\n  thin films: We report simulation results on melts of entangled linear polymers confined\nin a free-standing thin film. We study how the geometric constraints imposed by\nthe confinement alter the entanglement state of the system compared to the\nequivalent bulk system using various observables. We find that the confinement\ncompresses the chain conformation uniaxially, decreasing the volume pervaded by\nthe chain, which in turn reduces the number of the accessible inter-chain\ncontact that could lead to entanglements. This local and non-uniform effect\ndepends on the position of the chain within the film. We also test a recently\npresented theory that predicts how the number of entanglements decreases with\ngeometrical confinement.",
        "positive": "Controlling topological defects and contractile flow in confined nematic\n  cell population: Topological defects in nematically aligned cell populations play a critical\nrole in modulating collective motion, from microbial colonies to epithelial\ntissues. Despite the potential of manipulating such topological defects to\ncontrol diverse self-organized structures and collective dynamics, defect\nmanipulation in active matter remains an challenging area of research. In this\nstudy, we investigated the geometric control of defect positioning and\nalignment in a nematic cell population by imposing spatial constraints\nconsisting of two or three overlapping circular boundaries. The confined cell\npopulation exhibited an ordered pairing of half-integer topological defects\nthat remained stable even when the size of the spatial constraint was altered\nusing geometric parameters. These defects also elicited robust contractile flow\nthat induced a negative divergence in the velocity field of collective motion.\nSuch net contractile flow can contribute to mechanical stimulation on confined\ncells, as evidenced by the stretched cell nucleus. Our geometry-based approach\npaves the way for controlling defect pairing, providing a deeper understanding\nof the interplay among geometry, topology, and collective dynamics."
    },
    {
        "anchor": "How ill-defined constituents produce well-defined nanoparticles: Effect\n  of polymer dispersity on the uniformity of copolymeric micelles: We investigate the effect of polymer length dispersity on the properties of\nself-assembled micelles in solution by self-consistent field calculations.\nPolydispersity stabilizes micelles by raising the free energy barriers of\nmicelle formation and dissolution. Most importantly, it significantly reduces\nthe size fluctuations of micelles: Block copolymers of moderate polydispersity\nform more uniform particles than their monodisperse counterparts. We attribute\nthis to the fact that the packing of the solvophobic monomers in the core can\nbe optimized if the constituent polymers have different length.",
        "positive": "Effect of Functionalized CNT on Nematic anchoring: Nematic phase is the most fundamental mesophase exhibited by most of the rod\nshaped anisotropic liquid crystalline molecules. Nematics are orientationally\nordered fluids whose average orientation direction can be manipulated on\napplication of electric and magnetic fields. Carbon nanotube (CNT), a highly\nshape anisotropic object can find numerous industrial application because of\nits interesting electronic and mechanical properties. The self-organizing\nproperties of nematics can be used to align CNTs dispersed in them. We have\ndispersed functionalized CNTs in nematic liquid crystal and carried out many\nexperimental studies. We will present results of electro-optic switching and\ndielectric measurements on some CNT-LC dispersion. We have observed that\naddition of functionalized CNTs in a liquid crystal (LC) has led to improvement\nin the nematic ordering which is evidential from enhancement in dielectric\nanisotropy (De) measurement. These results indicate that the anchoring energy\nat alignment layers has been influenced by presence of FCNT in the LC host. The\nanchoring enhancement can be attributed to p-p electron stacking between the\nFCNT, LC and the alignment layer."
    },
    {
        "anchor": "A repulsive reference potential reproducing the dynamics of a liquid\n  with attractions: A well-known result of liquid state theory is that the structure of dense\nfluids is mainly determined by repulsive forces. The WCA potential, which cuts\nintermolecular potentials at their minima, is therefore often used as a\nreference. However, this reference gives quite wrong results for the viscous\ndynamics of the Kob-Andersen binary Lennard-Jones liquid [Berthier and Tarjus,\nPhys. Rev. Lett. 103, 170601 (2009)]. We show that repulsive inverse-power law\npotentials provide a useful reference for this liquid by reproducing its\nstructure, dynamics, and isochoric heat capacity.",
        "positive": "Clustering of topological defects in two-dimensional melting of active\n  and passive disks: We provide a quantitative analysis of all kinds of topological defects\npresent in 2D passive and active repulsive disk systems. We show that the\npassage from the solid to the hexatic is driven by the unbinding of\ndislocations. Instead, although we see dissociation of disclinations as soon as\nthe liquid phase appears, extended clusters of defects largely dominate below\nthe solid-hexatic critical line. The latter percolate at the hexatic-liquid\ntransition in continuous cases or within the coexistence region in\ndiscontinuous ones, and their form gets more ramified for increasing activity."
    },
    {
        "anchor": "Capillary Assembly of Colloids: Interactions on Planar and Curved\n  Interfaces: In directed assembly, small building clocks are assembled into an organized\nstructures under the influence of guiding fields. Capillary interactions\nprovide a versatile route for structure formation. Colloids adsorbed on fluid\ninterfaces distort the interface, which creates an associated energy field.\nWhen neighboring distortions overlap, colloids interact to minimize interfacial\narea. Contact line pinning, particle shape and surface chemistry play important\nroles in structure formation. Interface curvature acts like an external field;\nparticles migrate and assemble in patterns dictated by curvature gradients. We\nreview basic analysis and recent findings in this rapidly evolving literature.\nUnderstanding the roles of assembly is essential for tuning the mechanical,\nphysical, and optical properties of the structure.",
        "positive": "How does the scaling for the polymer chain in the dissipative particle\n  dynamics hold?: We performed a series of simulations for a linear polymer chain in a solvent\nusing dissipative particle dynamics to check the scaling relations for the\nend-to-end distance, radius of gyration and hydrodynamic radius in three\ndimensions. The polymer chains of up to 80 beads in explicit solvent of various\nquality are studied. To extract the scaling exponent \\nu, the data are analyzed\nusing linear fits, correction-to-scaling forms and analytical fits to the\nhistograms of radius of gyration distribution. For certain combinations of the\npolymer characteristics and solvent quality, the correction-to-scaling terms\nare found to be essential while for the others these are negligibly small. In\neach particular case the final value for the exponent \\nu was chosen according\nto the best least-squares fit. The values of \\nu obtained in this way are found\nwithin the interval \\nu=0.55-0.61 but are concentrated mostly around 0.59,\nwhich is very close to the best known theoretical result \\nu=0.588. The\nexistence of this interval is attributed both to the peculiarities of the\nmethod and to the moderate chain lengths being simulated. Within this\nshortcoming, the polymer chain in this kind of modeling is found to satisfy the\nscaling relations for all three radii being considered"
    },
    {
        "anchor": "Effect of Inertia on Linear Viscoelasticity of Harmonic Dumbbell Model: The overdamped (inertialess) dumbbell model is widely utilized to study\nrheological properties of polymers or other soft matters. In most cases, the\neffect of inertia is merely neglected because the momentum relaxation is much\nfaster than the bond relaxation. We theoretically analyze the effect of inertia\non the linear viscoelasticity of the harmonic dumbbell model. We show that the\nmomentum and bond relaxation modes are kinetically coupled and the inertia can\naffect the bond relaxation if the momentum relaxation is not sufficiently fast.\nWe derive an overdamped Langevin equation for the dumbbell model, which\nincorporates the weak inertia effect. Our model predicts the bond relaxation\ndynamics with the weak inertia effect correctly. We discuss how the weak\ninertia affects the linear viscoelasticity of a simple harmonic dumbbell model\nand the Rouse model.",
        "positive": "Jamming in sheared foams and emulsions, explained by critical\n  instability of the films between neighboring bubbles and drops: Phenomenon of foam and emulsion jamming at low shear rates is explained by\nconsidering the dynamics of thinning in the transient film, formed between the\nneighboring bubbles and drops. After gradually thinning down to a critical\nthickness, these films undergo instability transition and thin stepwise,\nforming the so-called \"black films\", which are only several nanometers thick\nand, thereby, lead to stronger adhesion between the dispersed particles.\nTheoretical analysis shows that such film thickness instability occurs only if\nthe contact time between the bubbles/drops in sheared foam/emulsion is\nsufficiently long, which corresponds to sufficiently low (critical) rate of\nshear. Explicit expression for this critical rate is proposed and compared to\nexperimental data."
    },
    {
        "anchor": "Creep, recovery, and waves in a nonlinear fiber-reinforced viscoelastic\n  solid: We present a constitutive model capturing some of the experimentally observed\nfeatures of soft biological tissues: nonlinear viscoelasticity, nonlinear\nelastic anisotropy, and nonlinear viscous anisotropy. For this model we derive\nthe equation governing rectilinear shear motion in the plane of the fiber\nreinforcement; it is a nonlinear partial differential equation for the shear\nstrain. Specializing the equation to the quasi-static processes of creep and\nrecovery, we find that usual (exponential-like) time growth and decay exist in\ngeneral, but that for certain ranges of values for the material parameters and\nfor the angle between the shearing direction and the fiber direction, some\nanomalous behaviors emerge. These include persistence of a nonzero strain in\nthe recovery experiment, strain growth in recovery, strain decay in creep,\ndisappearance of the solution after a finite time, and similar odd\ncomportments. For the full dynamical equation of motion, we find kink\n(traveling wave) solutions which cannot reach their assigned asymptotic limit.",
        "positive": "Surface forces generated by the action of electric fields across liquid\n  films: We explore the force generation and surface interactions arising when\nelectric fields are applied across fluid films. Using a surface force balance\n(SFB) we measure directly the force between two electrodes in crossed-cylinder\ngeometry across dielectric and electrolytic fluids. In the case of dielectric\nfilms the field between the electrodes exerts a force which can be well\nexplained using classic expressions and with no fitting parameters. However\nwhen the electrodes are separated by a film of electrolyte, an alternating\nelectric field induces a force which diverges substantially from the calculated\nstatic response of the electrolyte. The magnitude of the force is larger than\npredicted, and the interaction can switch from attractive to repulsive.\nFurthermore, the approach to steady state in electrolyte takes place over\n$10^2$ -- $10^3$~s which is very slow compared to both the charging and viscous\ntimescales of the system. The non-trivial electrolyte response in AC electric\nfields, measured here directly, is likely to underlie several recent reports of\nunexpected and bifurcating forces driving colloids in AC fields. Our\nmeasurements suggest ways to control colloidal and soft matter using electric\nfields, as well as providing a direct measure of the length- and time-scales\nrelevant in AC electrochemical and electrokinetic systems."
    },
    {
        "anchor": "Inter-Intra Molecular Dynamics as an Iterated Function System: The dynamics of units (molecules) with slowly relaxing internal states is\nstudied as an iterated function system (IFS) for the situation common in e.g.\nbiological systems where these units are subjected to frequent collisional\ninteractions. It is found that an increase in the collision frequency leads to\nsuccessive discrete states that can be analyzed as partial steps to form a\nCantor set. By considering the interactions among the units, a self-consistent\nIFS is derived, which leads to the formation and stabilization of multiple such\ndiscrete states. The relevance of the results to dynamical multiple states in\nbiomolecules in crowded conditions is discussed.",
        "positive": "Capillary condensation in an active bath: We study capillary condensation in a bath consisting of active Brownian\nparticles (ABPs) and the forces acting on the capillary close to the\nmotility-induced phase separation (MIPS). The capillary is modelled as two\nparallel rods of high aspect ratio which are fixed in space. We consider a bath\nof ABPs having a self-propulsion speed much larger than the critical speed\nnecessary for MIPS to occur. For a given particle speed, we gradually increase\nthe packing fraction of ABPs, starting from a homogeneous dilute phase of ABPs\nand going towards the binodal of MIPS. Depending on the packing fraction of\nABPs and capillary width, we find that the effective force between the\ncapillary rods can be either attractive or repulsive. In fact, with increasing\nwidth it shows damped oscillations as long as capillary condensation occurs. We\nanalyze them in detail by studying the distribution of particle distances from\nthe inner and outer wall of the capillary, respectively. In addition, we\nexamine the capillary in the active bath prepared under conditions close to the\ncritical point. We do not observe signs of the presence of long-range Casimir\ninteractions."
    },
    {
        "anchor": "The response function of a sphere in a viscoelastic two-fluid medium: In order to address basic questions of importance to microrheology, we study\nthe dynamics of a rigid sphere embedded in a model viscoelastic medium\nconsisting of an elastic network permeated by a viscous fluid. We calculate the\ncomplete response of a single bead in this medium to an external force and\ncompare the result to the commonly-accepted, generalized Stokes-Einstein\nrelation (GSER). We find that our response function is well approximated by the\nGSER only within a particular frequency range determined by the material\nparameters of both the bead and the network. We then discuss the relevance of\nthis result to recent experiments. Finally we discuss the approximations made\nin our solution of the response function by comparing our results to the exact\nsolution for the response function of a bead in a viscous (Newtonian) fluid.",
        "positive": "On the macroion virial contribution to the osmotic pressure in\n  charge-stabilized colloidal suspensions: Our interest goes to the different virial contributions to the equation of\nstate of charged colloidal suspensions. Neglect of surface effects in the\ncomputation of the colloidal virial term leads to spurious and paradoxical\nresults. This pitfall is one of the several facets of the danger of a naive\nimplementation of the so called One Component Model, where the micro-ionic\ndegrees of freedom are integrated out to only keep in the description the\nmesoscopic (colloidal) degrees of freedom. On the other hand, due incorporation\nof wall induced forces dissolves the paradox brought forth in the naive\napproach, provides a consistent description, and confirms that for salt-free\nsystems, the colloidal contribution to the pressure is dominated by the\nmicro-ionic one. Much emphasis is put on the no salt case but the situation\nwith added electrolyte is also discussed."
    },
    {
        "anchor": "Shear-density coupling for a compressible single-component yield-stress\n  fluid: Flow behavior of a single-component yield stress fluid is addressed on the\nhydrodynamic level. A basic ingredient of the model is a coupling between\nfluctuations of density and velocity gradient via a Herschel-Bulkley-type\nconstitutive model. Focusing on the limit of low shear rates and high\ndensities, the model approximates well---but is not limited to---gently sheared\nhard sphere colloidal glasses, where solvent effects are negligible. A detailed\nanalysis of the linearized hydrodynamic equations for fluctuations and the\nresulting cubic dispersion relation reveals the existence of a range of\ndensities and shear rates with growing flow heterogeneity. In this regime,\nafter an initial transient, the velocity and density fields monotonically reach\na spatially inhomogeneous stationary profile, where regions of high shear rate\nand low density coexist with regions of low shear rate and high density. The\nsteady state is thus maintained by a competition between shear-induced\nenhancement of density inhomogeneities and relaxation via overdamped sound\nwaves. An analysis of the mechanical equilibrium condition provides a criterion\nfor the existence of steady state solutions. The dynamical evolution of the\nsystem is discussed in detail for various boundary conditions, imposing either\na constant velocity, shear rate, or stress at the walls.",
        "positive": "Dynamical classical superfluid-insulator transition in a Bose-Einstein\n  condensate on an optical lattice: We predict a dynamical classical superfluid-insulator transition in a\nBose-Einstein condensate (BEC) trapped in a combined optical and\naxially-symmetric harmonic potentials initiated by a periodic modulation of the\nradial trapping potential. The transition is marked by a loss of phase\ncoherence in the BEC and a subsequent destruction of the interference pattern\nupon free expansion. For a weak modulation of the radial potential the phase\ncoherence is maintained. For a stronger modulation and a longer time of holding\nin the modulated trap, the phase coherence is destroyed signaling a classical\nsuperfluid-insulator transition. The results are illustrated by a complete\nnumerical solution of the axially-symmetric mean-field Gross-Pitaevskii\nequation for a repulsive BEC. Suggestion for future experiment is made."
    },
    {
        "anchor": "Realizing a Four-Step Molecular Switch in Scanning Tunneling Microscope\n  Manipulation of Single Chlorophyll-a Molecules: Single chlorophyll-a molecules, a vital resource for the sustenance of life\non Earth, have been investigated by using scanning-tunneling-microscope\nmanipulation and spectroscopy on a gold substrate at 4.6 K. The chlorophyll-a\nbinds on Au(111) via its porphyrin unit while the phytyl-chain is elevated from\nthe surface by a support of four CH3 groups. By injecting tunneling electrons\nfrom the STM-tip, we are able to bend the phytyl-chain, which enable switching\nof four molecular conformations in a controlled manner. Statistical analyses\nand structural calculations reveal that all reversible switching mechanisms are\ninitiated by a single tunnelling-electron energy-transfer process, which\ninduces bond rotation within the phytyl-chain.",
        "positive": "Theoretical and numerical investigations of inverse patchy colloids in\n  the fluid phase: We investigate the structural and thermodynamic properties of a new class of\npatchy colloids, referred to as inverse patchy colloids (IPCs) in their fluid\nphase via both theoretical methods and simulations. IPCs are nano- or micro-\nmeter sized particles with differently charged surface regions. We extend\nconventional integral equation schemes to this particular class of systems: our\napproach is based on the so-called multi-density Ornstein-Zernike equation,\nsupplemented by the associative Percus-Yevick approximation (APY). To validate\nthe accuracy of our framework, we compare the obtained results with data\nextracted from $NpT$ and $NVT$ Monte Carlo simulations. In addition, other\ntheoretical approaches are used to calculate the properties of the system: the\nreference hypernetted-chain (RHNC) method and the Barker-Henderson\nthermodynamic perturbation theory. Both APY and RHNC frameworks provide\naccurate predictions for the pair distribution functions: APY results are in\nslightly better agreement with MC data, in particular at lower temperatures\nwhere the RHNC solution does not converge."
    },
    {
        "anchor": "Bio-inspired acousto-magnetic microswarm robots with upstream motility: The ability to propel against flows, i.e., to perform positive rheotaxis, can\nprovide exciting opportunities for applications in targeted therapeutics and\nnon-invasive surgery. To date, no biocompatible technologies exist for\nnavigating microparticles upstream when they are in a background fluid flow.\nInspired by many naturally occurring microswimmers such as bacteria,\nspermatozoa, and plankton that utilize the non-slip boundary conditions of the\nwall to exhibit upstream propulsion, here, we report on the design and\ncharacterization of self-assembled microswarms that can execute upstream\nmotility in a combination of external acoustic and magnetic fields. Both\nacoustic and magnetic fields are safe to humans, non-invasive, can penetrate\ndeeply into the human body, and are well-developed in clinical settings. The\ncombination of both fields can overcome the limitations encountered by single\nactuation methods. The design criteria of the acoustically-induced reaction\nforce of the microswarms, which is needed to perform rolling-type motion, are\ndiscussed. We show quantitative agreement between experimental data and our\nmodel that captures the rolling behaviour. The upstream capability provides a\ndesign strategy for delivering small drug molecules to hard-to-reach sites and\nrepresents a fundamental step toward the realization of micro- and\nnanosystem-navigation against the blood flow.",
        "positive": "On free vibration of piezoelectric nanospheres with surface effect: Surface effect responsible for some size-dependent characteristics can become\ndistinctly important for piezoelectric nanomaterials with inherent large\nsurface-to-volume ratio. In this paper, we investigate the surface effect on\nthe free vibration behavior of a spherically isotropic piezoelectric\nnanosphere. Instead of directly using the well-known Huang-Yu surface\npiezoelectricity theory (HY theory), another general framework based on a thin\nshell layer model is proposed. A novel approach is developed to establish the\nsurface piezoelectricity theory or the effective boundary conditions for\npiezoelectric nanospheres employing the state-space formalism. Three different\nsources of surface effect can be identified in the first-order surface\npiezoelectricity, i.e. the electroelastic effect, the inertia effect, and the\nthickness effect. It is found that the proposed theory becomes identical to the\nHY theory for a spherical material boundary if the transverse stress (TS)\ncomponents are discarded and the electromechanical properties are properly\ndefined. The nonaxisymmetric free vibration of a piezoelectric nanosphere with\nsurface effect is then studied and an exact solution is obtained. In order to\ninvestigate the surface effect on the natural frequencies of piezoelectric\nnanospheres, numerical calculations are finally performed. Our numerical\nfindings demonstrate that the surface effect, especially the thickness effect,\nmay have a particularly significant influence on the free vibration of\npiezoelectric nanospheres. This work provides a more accurate prediction of the\ndynamic characteristics of piezoelectric nanospherical devices in\nNano-Electro-Mechanical Systems (NEMS)."
    },
    {
        "anchor": "Uncovering the molecular mechanism for dual effect of ATP on phase\n  separation in FUS solution: Recent studies reported that adenosine triphosphate (ATP) could inhibit as\nwell as enhance the phase separation in prion-like proteins. The molecular\nmechanism underlying such a puzzling phenomenon remains elusive. Here, taking\nthe fused in sarcoma (FUS) solution as an example, we comprehensively reveal\nthe underlying mechanism by which ATP regulates phase separation by combining\nthe semiempirical quantum mechanical method, mean-field theory, and molecular\nsimulation. At the microscopic level, ATP acts as a bivalent or trivalent\nbinder; at the macroscopic level, the reentrant phase separation indeed occurs\nin dilute FUS solutions, resulting from the ATP-concentration--dependent\nbinding ability under different conditions. Importantly, the ATP concentration\nfor dissolving the protein condensates is about 10 mM, agreeing with\nexperimental results. Furthermore, from a dynamic point of view, the effect of\nATP on phase separation is also non-monotonic. This work provides a clear\nphysical description of the microscopic interaction and macroscopic phase\ndiagram of the ATP-modulated phase separation.",
        "positive": "Line tension and structure of smectic liquid crystal multilayers at the\n  air-water interface: At the air/water interface, 4,-8-alkyl[1,1,-biphenyl]-4-carbonitrile (8CB)\ndomains with different thicknesses coexist in the same Langmuir film, as\nmultiple bilayers on a monolayer. The edge dislocation at the domain boundary\nleads to line tension, which determines the domain shape and dynamics. By\nobserving the domain relaxation process starting from small distortions, we\nfind that the line tension is linearly dependent on the thickness difference\nbetween the coexisting phases in the film. Comparisons with theoretical\ntreatments in the literature suggest that the edge dislocation at the boundary\nlocates near the center of the film, which means that the 8CB multilayers are\nalmost symmetric with respect to the air/water interface."
    },
    {
        "anchor": "Third and Fifth Harmonic Responses in Viscous Liquids: We review the works devoted to third and fifth harmonic susceptibilities in\nglasses, namely $\\chi$ (3) 3 and $\\chi$ (5) 5. We explain why these nonlinear\nresponses are especially well adapted to test whether or not some amorphous\ncorrelations develop upon cooling. We show that the experimental frequency and\ntemperature dependences of $\\chi$ (3) 3 and of $\\chi$ (5) 5 have anomalous\nfeatures, since their behavior is qualitatively different to that of an ideal\ngas, which is the high-temperature limit of a fluid. Most of the works have\ninterpreted this anomalous behavior as reflecting the growth, upon cooling, of\namorphously ordered domains, as predicted by the general framework of Bouchaud\nand Biroli (BB). We explain why most-if not all-of the challenging\ninterpretations can be recast in a way which is consistent with that of\nBouchaud and Biroli. Finally, the comparison of the anomalous features of\n$\\chi$ (5) 5 and of $\\chi$ (3) 3 shows that the amorphously ordered domains are\ncompact, i.e., the fractal dimension d f is close to the dimension d of space.\nThis suggests that the glass transition of molecular liquids corresponds to a\nnew universality class of critical phenomena.",
        "positive": "Phase Diagram of a Reentrant Gel of Patchy Particles: We study the phase diagram of a binary mixture of patchy particles which has\nbeen designed to form a reversible gel. For this we perform Monte Carlo and\nmolecular dynamics simulations to investigate the thermodynamics of such a\nsystem and compare our numerical results with predictions based on the\nanalytical parameter-free Wertheim theory. We explore a wide range of the\ntemperature-density-composition space that defines the three-dimensional phase\ndiagram of the system. As a result, we delimit the region of thermodynamic\nstability of the fluid. We find that for a large region of the phase diagram\nthe Wertheim theory is able to give a quantitative description of the system.\nFor higher densities our simulations show that the system is crystallizing into\na BCC structure. Finally we study the relaxation dynamics of the system by\nmeans of the density and temperature dependences of the diffusion coefficient.\nWe show that there exists a density range where the system passes reversibly\nfrom a gel to a fluid upon both heating and cooling, encountering neither\ndemixing nor phase separation."
    },
    {
        "anchor": "The nature of attraction between like charged rods: Comment on the paper of Ha and Liu (Phys. Rev. Lett. {\\bf 79}, 1289 (1997))\nregarding the nature of attraction between like charged rods. We demostrate\nthat their results do not produce the correct low temperature limit.",
        "positive": "Effect of nonlinear filters on detrended fluctuation analysis: We investigate how various linear and nonlinear transformations affect the\nscaling properties of a signal, using the detrended fluctuation analysis (DFA).\nSpecifically, we study the effect of three types of transforms: linear,\nnonlinear polynomial and logarithmic filters. We compare the scaling properties\nof signals before and after the transform. We find that linear filters do not\nchange the correlation properties, while the effect of nonlinear polynomial and\nlogarithmic filters strongly depends on (a) the strength of correlations in the\noriginal signal, (b) the power of the polynomial filter and (c) the offset in\nthe logarithmic filter. We further investigate the correlation properties of\nthree analytic functions: exponential, logarithmic, and power-law. While these\nthree functions have in general different correlation properties, we find that\nthere is a broad range of variable values, common for all three functions,\nwhere they exhibit identical scaling behavior. We further note that the scaling\nbehavior of a class of other functions can be reduced to these three typical\ncases. We systematically test the performance of the DFA method in accurately\nestimating long-range power-law correlations in the output signals for\ndifferent parameter values in the three types of filters, and the three\nanalytic functions we consider."
    },
    {
        "anchor": "Dynamics and Scission of Rodlike Cationic Surfactant Micelles in Shear\n  Flow: Flow-induced configuration dynamics and scission of rodlike micelles are\nstudied for the first time using molecular dynamics simulations in presence of\nexplicit solvent and salt. Predicted dependence of tumbling frequency and\norientation distribution on shear rate S agrees with mesoscopic theories.\nHowever, micelle stretching increases the distance between the cationic head\ngroups and adsorbed counter ions, which reduces electrostatic screening and\nincreases the overall energy Phi linearly with micelle length. Micelle scission\noccurs when Phi exceeds a threshold value, independent of S.",
        "positive": "Influence of chain topology and bond potential on the glass transition\n  of polymer chains simulated with the bond fluctuation model: The bond fluctuation model with a bond potential has been applied to\ninvestigation of the glass transition of linear chains and chains with a\nregular disposition of small branches. Cooling and subsequent heating curves\nare obtained for the chain energies and also for the mean acceptance\nprobability of a bead jump. In order to mimic different trends to\nvitrification, a factor B gauging the strength of the bond potential with\nrespect to the long-range potential (i.e. the intramolecular or intermolecular\npotential between indirectly bonded beads) has been introduced. (A higher value\nof B leads to a preference for the highest bond lengths and a higher total\nenergy, implying a greater tendency to vitrify.) Different cases have been\nconsidered for linear chains: no long-range potential, no bond potential and\nseveral choices for B. Furthermore, we have considered two distinct values of B\nfor alternate bonds in linear chains. In the case of the branched chains,\nmolecules with different values of B for bonds in the main chain and in the\nbranches have also been investigated. The possible presence of crystallization\nhas been characterized by calculating the collective light scattering function\nof the different samples after annealing at a convenient temperature below the\nonset of crystallization. It is concluded that crystallization is inherited\nmore efficiently in the systems with branched chains and also for higher values\nof B. The branched molecules with the highest B values in the main chain bonds\nexhibit two distinct transitions in the heating curves which may be associated\nwith two glass transitions. This behavior has been detected experimentally for\nchains with relatively long flexible branches."
    },
    {
        "anchor": "Instantaneous Liquid Interfaces: We describe and illustrate a simple procedure for identifying a liquid\ninterface from atomic coordinates. In particular, a coarse grained density\nfield is constructed, and the interface is defined as a constant density\nsurface for this coarse grained field. In applications to a molecular dynamics\nsimulation of liquid water, it is shown that this procedure provides\ninstructive and useful pictures of liquid-vapor interfaces and of\nliquid-protein interfaces.",
        "positive": "Linking in domain-swapped protein dimers: The presence of knots has been observed in a small fraction of single-domain\nproteins and related to their thermodynamic and kinetic properties. The\nexchanging of identical structural elements, typical of domain-swapped\nproteins, make such dimers suitable candidates to validate the possibility that\nmutual entanglement between chains may play a similar role for protein\ncomplexes. We suggest that such entanglement is captured by the linking number.\nThis represents, for two closed curves, the number of times that each curve\nwinds around the other. We show that closing the curves is not necessary, as a\nnovel parameter $G'$, termed Gaussian entanglement, is strongly correlated with\nthe linking number. Based on $110$ non redundant domain-swapped dimers, our\nanalysis evidences a high fraction of chains with a significant intertwining,\nthat is with $|G'| > 1$. We report that Nature promotes configurations with\nnegative mutual entanglement and surprisingly, it seems to suppress\nintertwining in long protein dimers. Supported by numerical simulations of\ndimer dissociation, our results provide a novel topology-based classification\nof protein-swapped dimers together with some preliminary evidence of its impact\non their physical and biological properties."
    },
    {
        "anchor": "Sitting at the edge: How biomolecules use hydrophobicity to tune their\n  interactions and function: Water near hydrophobic surfaces is like that at a liquid-vapor interface,\nwhere fluctuations in water density are substantially enhanced compared to that\nin bulk water. Here we use molecular simulations with specialized sampling\ntechniques to show that water density fluctuations are similarly enhanced, even\nnear hydrophobic surfaces of complex biomolecules, situating them at the edge\nof a dewetting transition. Consequently, water near these surfaces is sensitive\nto subtle changes in surface conformation, topology, and chemistry, any of\nwhich can tip the balance towards or away from the wet state, and thus\nsignificantly alter biomolecular interactions and function. Our work also\nresolves the long-standing puzzle of why some biological surfaces dewet and\nother seemingly similar surfaces do not.",
        "positive": "Single-particle and collective slow dynamics of colloids in porous\n  confinement: Using molecular dynamics simulations we study the slow dynamics of a hard\nsphere fluid confined in a disordered porous matrix. The presence of both\ndiscontinuous and continuous glass transitions as well as the complex interplay\nbetween single-particle and collective dynamics are well captured by a recent\nextension of mode-coupling theory for fluids in porous media. The degree of\nuniversality of the mode-coupling theory predictions for related models of\ncolloids is studied by introducing size-disparity between fluid and matrix\nparticles, as well as softness in the interactions."
    },
    {
        "anchor": "Defect removal by solvent vapor annealing in thin films of lamellar\n  diblock copolymers: Solvent vapor annealing (SVA) is known to be a simple, low-cost and highly\nefficient technique to produce defect-free diblock copolymer (BCP) thin films.\nNot only can the solvent weaken the BCP segmental interactions, but it can vary\nthe characteristic spacing of the BCP microstructures. We carry out systematic\ntheoretical studies on the effect of adding solvent into lamellar BCP thin\nfilms on the defect removal close to the BCP order-disorder transition. We find\nthat the increase of the lamellar spacing, as is induced by addition of\nsolvent, facilitates more efficient removal of defects. The stability of a\nparticular defect in a lamellar BCP thin film is given in terms of two key\ncontrollable parameters: the amount of BCP swelling and solvent evaporation\nrate. Our results highlight the SVA mechanism for obtaining defect-free BCP\nthin films, as is highly desired in nanolithography and other industrial\napplications.",
        "positive": "Self-propulsion of a light-powered microscopic crystalline flapper in\n  water: A key goal in developing molecular microrobots that mimic real-world animal\ndynamic behavior is to understand better the self-continuous progressive motion\nresulting from collective molecular transformation. This study reports, for the\nfirst time, the experimental realization of directional swimming of a\nmicrocrystal that exhibits self-continuous reciprocating motion in a\ntwo-dimensional water tank. Although the reciprocal flip motion of the crystals\nwas like that of a fish wagging its tail fin, many of the crystals swam in the\nopposite direction to which a fish would swim. Here we explore the\ndirectionality generation mechanism and physical features of the swimming\nbehavior by constructing a mathematical model for the crystalline flapper. The\nresults show that a tiny crystal with a less-deformable part in its flip fin\nexhibits a pull-type stroke swimming, while a crystal with a fin that uniformly\ndeforms exhibits push-type kicking motion."
    },
    {
        "anchor": "Fluid squeeze-out between rough surfaces: comparison of theory with\n  experiment: We study the time dependency of the (average) interfacial separation between\nan elastic solid with a flat surface and a rigid solid with a randomly rough\nsurface, squeezed together in a fluid. We use an analytical theory describing\nthe fluid flow factors, based on the Persson contact mechanics theory and the\nBruggeman effective medium theory, to calculate the removal of the fluid from\nthe contacting interface of the two solids. In order to test this approach, we\nhave performed simple squeeze-out experiments. The experimental results are\ncompared to the theory predictions.",
        "positive": "The Glass Transition of Thin Polymer Films: Some Questions, and a\n  Possible Answer: A simple and predictive model is put forward explaining the experimentally\nobserved substantial shift of the glass transition temperature, Tg, of\nsufficiently thin polymer films. It focuses on the limit of small molecular\nweight, where geometrical `finite size' effects on the chain conformation can\nbe ruled out. The model is based on the idea that the polymer freezes due to\nmemory effects in the viscoelastic eigenmodes of the film, which are affected\nby the proximity of the boundaries. The elastic modulus of the polymer at the\nglass transition turns out to be the only fitting parameter. Quantitative\nagreement is obtained with our experimental results on short chain polystyrene\n(Mw = 2 kg/mol), as well as with earlier results obtained with larger\nmolecules. Furthermore, the model naturally accounts for the weak dependence of\nthe shift of Tg upon the molecular weight. It furthermore explains why\nsupported films must be thinner than free standing ones to yield the same\nshift, and why the latter depends upon the chemical properties of the\nsubstrate. Generalizations for arbitrary experimental geometries are\nstraightforward."
    },
    {
        "anchor": "Insights into bubble droplet interactions in evaporating polymeric\n  droplets: Polymer droplets subjected to a heated environment have significance in\nseveral fields ranging from spray drying and powder formation to surface\ncoating. In the present work, we investigate the evaporation of a high\nviscoelastic modulus aqueous polymeric droplet in an acoustically levitated\nenvironment. Depending on the laser irradiation intensity, we observe\nnucleation of a bubble in the dilute regime of polymer concentration, contrary\nto the previously observed bubble nucleation in a semi-dilute entangled regime\nfor low viscoelastic modulus polymer droplets. After the bubble nucleation, a\nquasi steady bubble growth occurs depending on the laser irradiation intensity\nand concentrations. Our scaling analysis reveals that bubble growth follows\nPlesset-Zwick criteria independent of the viscoelastic properties of the\npolymer solution. Further, we establish that the onset of bubble growth has an\ninverse nonlinear dependence on the laser irradiation intensity. At high\nconcentrations and laser irradiation intensities, we report the expansion and\ncollapse of polymer membrane without rupture, indicating the formation of an\ninterfacial skin with significant strength. The droplet oscillations are\nprimarily driven by the presence of multiple bubbles and, to some extent, by\nthe rotational motion of the droplet. Finally, depending on the nature of\nbubble growth, different types of precipitate form contrary to the different\nmodes of atomization observed in low viscoelastic modulus polymer droplets.",
        "positive": "Defects in vertically vibrated monolayers of cylinders: We analyse liquid-crystalline ordering in vertically vibrated monolayers of\ncylinders confined in a circular cavity. Short cylinders form tetratic\narrangements with C$_4$ symmetry. This symmetry, which is incompatible with the\ngeometry of the cavity, is restored by the presence of four point defects with\ntotal topological charge $+4$. Equilibrium Monte Carlo simulations predict the\nsame structure. A new method to measure the elastic properties of the tetratic\nmedium is developed which exploits the clear similarities between the vibrated\ndissipative system and the thermal equilibrium system. Our observations open up\na new avenue to investigate the formation of defects in response to boundary\nconditions, an issue which is very difficult to realize in colloidal or\nmolecular systems."
    },
    {
        "anchor": "Experimental properties of Bose-Einstein condensates in 1D optical\n  lattices: Bloch oscillations, Landau-Zener tunneling and mean-field effects: We report experimental results on the properties of Bose-Einstein condensates\nin 1D optical lattices. By accelerating the lattice, we observed Bloch\noscillations of the condensate in the lowest band, as well as Landau-Zener\n(L-Z) tunneling into higher bands when the lattice depth was reduced and/or the\nacceleration of the lattice was increased. The dependence of the L-Z tunneling\nrate on the condensate density was then related to mean-field effects modifying\nthe effective potential acting on the condensate, yielding good agreement with\nrecent theoretical work. We also present several methods for measuring the\nlattice depth and discuss the effects of the micromotion in the TOP-trap on our\nexperimental results.",
        "positive": "Comment on \"Crossover of collective modes and positive sound dispersion\n  in supercritical state\": We comment on an expression for positive sound dispersion (PSD) in fluids and\nanalysis of PSD from molecular dynamics simulations reported in the Letter by\nFomin et al (J.Phys.:Condens.Matt. v.28, 43LT01, 2016)"
    },
    {
        "anchor": "Scattering from Colloid-Polymer Conjugates with Excluded Volume Effect: In this work we present scattering functions of conjugates consisting of a\ncolloid particle and a self-avoiding polymer chain. This model is directly\nderived from the two point correlation function with the inclusion of excluded\nvolume effects. The dependence of the calculated scattering function on the\ngeometric shapes of the colloid and polymer stiffness is investigated. In\ncomparison to existing experimental results, our model is found to be able to\ndescribe the scattering signature of the colloid-polymer conjugates and provide\nadditional conformational information. This model explicitly elucidates the\nlink between the global conformation of a conjugate and the microstructure of\nits constituent components.",
        "positive": "Power law creep and delayed failure of gels and fibrous materials under\n  stress: Motivated by recent experiments studying the creep and breakup of a protein\ngel under stress, we introduce a simple mesoscopic model for the irreversible\nfailure of gels and fibrous materials, and demonstrate it to capture much of\nthe phenomenology seen experimentally. This includes a primary creep regime in\nwhich the shear rate decreases as a power law over several decades of time, a\nsecondary crossover regime in which the shear rate attains a minimum, and a\ntertiary regime in which the shear rate increases dramatically up to a finite\ntime singularity, signifying irreversible material failure. The model also\ncaptures a linear Monkman-Grant scaling of the failure time with the earlier\ntime at which the shear rate attained its minimum, and a Basquin-like power law\nscaling of the failure time with imposed stress, as seen experimentally. The\nmodel furthermore predicts a slow accumulation of low levels of material damage\nduring primary creep, followed by the growth of fractures leading to sudden\nmaterial failure, as seen experimentally."
    },
    {
        "anchor": "Magneto-optical granulometry: on the determination of the statistics of\n  magnetically induced particle chains in concentrated ferrofluids from linear\n  dichroism experiments: An analytical theoretical model for the influence of the magnetically induced\nnanoparticle chaining on the linear dichroism in ferrofluids was developed. The\nmodel is based on a statistical theory for magnetic nanoparticle chaining in\nferrofluids. Together with appropriate experimental approach and data\nprocessing strategy, the model grounds a magneto-optical granulometry method\nable to determine the magnetic field dependence of the statistics of\nmagnetically induced particle chains in concentrated ferrofluids.",
        "positive": "Effect of confinement on the mechanics of a swelling hydrogel bead: We recast the problem of hydrogel swelling under physical constraints as an\nenergy optimization problem. We apply this approach to compute equilibrium\nshapes of hydrogel spheres confined within a jammed matrix of rigid beads, and\ninterpret the results to determine how confinement modifies the mechanics of\nswollen hydrogels. In contrast to the unconfined case, we find a spatial\nseparation of strains within the bulk of the hydrogel as strain becomes\nlocalized to an outer region. We also explore the contact mechanics of the gel,\nfinding a transition from Hertzian behavior to non-Hertzian behavior as a\nfunction of swelling. Our model, implemented in the Morpho shape optimization\nenvironment, can be applied in any dimension, readily adapted to diverse\nswelling scenarios and extended to use other energies in conjunction."
    },
    {
        "anchor": "Translational and Rotational Dynamics of Colloidal Particles Interacting\n  through Reacting Linkers: Much work has studied effective interactions between micron-sized particles\ncarrying linkers forming reversible, inter-particle linkages. These studies\nallowed understanding the equilibrium properties of colloids interacting\nthrough ligand-receptor interactions. Nevertheless, understanding the kinetics\nof multivalent interactions remains an open problem. Here, we study how\nmolecular details of the linkers, such as the reaction rates at which\ninter-particle linkages form/break, affect the relative dynamics of pairs of\ncross-linked colloids. Using a simulation method tracking single\nbinding/unbinding events between complementary linkers, we rationalize recent\nexperiments and prove that particles' interfaces can move across each other\nwhile being cross-linked. We clarify how, starting from diffusing colloids, the\ndynamics become arrested when increasing the number of inter-particle linkages\nor decreasing the reaction rates. Before getting arrested, particles diffuse\nthrough rolling motion. The ability to detect rolling motion will be useful to\nshed new light on host-pathogen interactions.",
        "positive": "Berry phase caused by nondissipative drag of superflow in a Bose qubit: A microscopic theory of superfluid drag in a two-component Bose gas is\ndeveloped. The drag factor is shown to be proportional to the square root of\nthe gas parameter. Basing on the similarity between the drag force and vector\npotential of magnetic field we propose how the superfluid drag can be used to\ndetect a Berry phase in a Bose counterpart of the Josephson charge qubit. We\nconsider a system in which the drag component, situated inside the drive\ncomponent, is confined in two half-ring traps separated by two Josephson\nbarriers. Under cyclic adiabatic change of Josephson coupling parameters and an\nasymmetry of two traps a Berry phase is generated. This phase can be observed\nthough measurements of relative number of atoms in two traps. The Berry phase\ndepends on the drag factor and its detection can be used for determining the\nvalue of the drag."
    },
    {
        "anchor": "Linking particle properties to paste extrusion flow characteristics\n  using discrete element simulations: Extrusion is a widely used process for forming pastes into designed shapes,\nand is central to the manufacture of many industrial products. The extrusion\nthrough a square-entry die of a model paste of non-Brownian spheres suspended\nin a Newtonian fluid is investigated using discrete element simulations,\ncapturing individual particle contacts and hydrodynamic interactions. The\nsimulations reveal inhomogeneous velocity and stress distributions, originating\nin the inherent microstructure formed by the constituent particles. Such\nfeatures are shown to be relevant to generic paste extrusion behaviour, such as\ndie swell. The pressure drop across the extruder is correlated with the\nextrudate velocity using the Benbow-Bridgwater equation, with the empirical\nparameters being linked directly to particle properties such as surface\nfriction, and processing conditions such as extruder wall roughness. Our model\nand results bring recent advances in suspension rheology into an industrial\nsetting, laying foundations for future model development, paste formulation and\nextrusion design.",
        "positive": "Creeping Avalanches of Brownian Granular Suspensions: We study the avalanche dynamics of a pile of micron-sized silica grains in\nminiaturized rotating drums filled with water. Contrary to what is expected for\nclassical granular materials, the avalanches do not stop at a finite angle of\nrepose. Below an angle $\\theta$\\_c, we observe a creep regime where the piles\nslowly flow until they become flat. In this regime, the relaxation is\nlogarithmic in time and is slower when the ratio between the weight of the\ngrains and the thermal agitation is increased. We propose a simple 1D model\nbased on Kramer's escape rate to describe this flow."
    },
    {
        "anchor": "Glass transition in Ultrathin Polymer Films : A Thermal Expansion Study: Glass transition process gets affected in ultrathin films having thickness\ncomparable to the size of the molecules. We observe systematic broadening of\nglass transition temperature (Tg) as the thickness of the polymer film reduces\nbelow the radius of gyration but the change in the average Tg was found to be\nvery small. Existence of reversible negative and positive thermal expansion\nbelow and above Tg increased the sensitivity of our thickness measurements\nperformed using energy dispersive x-ray reflectivity. A simple model of Tg\nvariation as a function of depth expected from sliding motion could explain the\nresults. We observe clear glass transition even for 4 nm polystyrene film that\nwas predicted to be absent from ellipsometry measurements of thicker films.",
        "positive": "Interrupted Motility Induced Phase Separation in Aligning Active\n  Colloids: Switching on high activity in a relatively dense system of active Janus\ncolloids, we observe fast clustering, followed by cluster aggregation towards\nfull phase separation. The phase separation process is however interrupted when\nlarge enough clusters start breaking apart. Following the cluster size\ndistribution as a function of time, we identify three successive dynamical\nregimes. Tracking both the particle positions and orientations, we characterize\nthe structural ordering and alignment in the growing clusters and thereby\nunveil the mechanisms at play in these regimes. In particular, we identify how\nalignment between the neighboring particles is responsible for the interruption\nof the full phase separation. This experimental study, which provides the first\nlarge scale observation of the phase separation kinetics in active colloids,\ncombined with single particle analysis of the local mechanisms, points towards\nthe new physics observed when both alignment and short-range repulsions are\npresent."
    },
    {
        "anchor": "Collective diffusion of a colloidal particles in a liquid crystal: The collective diffusion effects in system of a colloidal particles in a\nliquid crystal has been proposed. In this article described peculiarity of\ncollective diffusion colloidal particles in a liquid crystal, which can be\nobserve experimentally. The diffusion coefficient should be crucial dependence\nfrom temperature and concentration of particles. In system colloidal particles\narise from the elastic distortion of the elastic director field the\ninter-particle interaction. These interaction can cause nontrivial collective\nbehavior, as the results the non-monotonic dependence collective diffusion. Are\npredicted a nontrivial behavior collective diffusion of colloidal particles in\na liquid crystal.",
        "positive": "Shear Induced Orientational Ordering in Active Glass: Dense assemblies of self propelled particles, also known as active or living\nglasses are abundantaround us, covering different length and time scales: from\nthe cytoplasm to tissues, from bacterialbio-films to vehicular traffic jams,\nfrom Janus colloids to animal herds. Being structurally disorderedas well as\nstrongly out of equilibrium, these systems show fascinating dynamical and\nmechanicalproperties. Using extensive molecular dynamics simulation and a\nnumber of different dynamicaland mechanical order parameters we differentiate\nthree dynamical steady states in a sheared modelactive glassy system: (a) a\ndisordered phase, (b) a propulsion-induced ordered phase, and (c)\nashear-induced ordered phase. We supplement these observations with an\nanalytical theory based onan effective single particle Fokker-Planck\ndescription to rationalise the existence of the novel shear-induced\norientational ordering behaviour in our model active glassy system that has no\nexplicitaligning interactions,e.g.of Vicsek-type. This ordering phenomenon\noccurs in the large persistencetime limit and is made possible only by the\napplied steady shear. Using a Fokker-Planck descriptionwe make testable\npredictions without any fit parameters for the joint distribution of single\nparticleposition and orientation. These predictions match well with the joint\ndistribution measured fromdirect numerical simulation. Our results are of\nrelevance for experiments exploring the rheologicalresponse of dense active\ncolloids and jammed active granular matter systems."
    },
    {
        "anchor": "Modelling the unfolding pathway of biomolecules: theoretical approach\n  and experimental prospect: We analyse the unfolding pathway of biomolecules comprising several\nindependent modules in pulling experiments. In a recently proposed model, a\ncritical velocity $v_{c}$ has been predicted, such that for pulling speeds\n$v>v_{c}$ it is the module at the pulled end that opens first, whereas for\n$v<v_{c}$ it is the weakest. Here, we introduce a variant of the model that is\ncloser to the experimental setup, and discuss the robustness of the emergence\nof the critical velocity and of its dependence on the model parameters. We also\npropose a possible experiment to test the theoretical predictions of the model,\nwhich seems feasible with state-of-art molecular engineering techniques.",
        "positive": "Statistical Mechanics of Transport Processes in Active Fluids II:\n  Equations of Hydrodynamics for Active Brownian Particles: We perform a coarse-graining analysis of the paradigmatic active matter\nmodel, Active Brownian Particles, yielding a continuum description in terms of\nbalance laws for mass, linear and angular momentum, and energy. The derivation\nof the balance of linear momentum reveals that the active force manifests\nitself directly as a continuum-level body force proportional to an order\nparameter-like director field, which therefore requires its own evolution\nequation to complete the continuum description of the system. We derive this\nequation, demonstrating in the process that bulk currents may be sustained in\nhomogeneous systems only in the presence of inter-particle aligning\ninteractions. Further, we perform a second coarse-graining of the balance of\nlinear momentum and derive the expression for active or swim pressure in the\ncase of mechanical equilibrium."
    },
    {
        "anchor": "Efficient simulation of non-crossing fibers and chains in a hydrodynamic\n  solvent: An efficient simulation method is presented for Brownian fiber suspensions,\nwhich includes both uncrossability of the fibers and hydrodynamic interactions\nbetween the fibers mediated by a mesoscopic solvent. To conserve hydrodynamics,\ncollisions between the fibers are treated such that momentum and energy are\nconserved locally. The choice of simulation parameters is rationalised on the\nbasis of dimensionless numbers expressing the relative strength of different\nphysical processes. The method is applied to suspensions of semiflexible fibers\nwith a contour length equal to the persistence length, and a mesh size to\ncontour length ratio ranging from 0.055 to 0.32. For such fibers the effects of\nhydrodynamic interactions are observable, but relatively small. The\nnon-crossing constraint, on the other hand, is very important and leads to\nhindered displacements of the fibers, with an effective tube diameter in\nagreement with recent theoretical predictions. The simulation technique opens\nthe way to study the effect of viscous effects and hydrodynamic interactions in\nmicrorheology experiments where the response of an actively driven probe bead\nin a fiber suspension is measured.",
        "positive": "Quinary lattice model of secondary structures of polymers: In the standard approach to lattice proteins the models based on nearest\nneighbor interaction are used. In this kind of models it is difficult to\nexplain the existence of secondary structures --- special preferred\nconformations of protein chains.\n  In the present paper a new lattice model of proteins is proposed which is\nbased on non-local cooperative interactions. In this model the energy of a\nconformation of a polymer is equal to the sum of energies of conformations of\nfragments of the polymer chain of the length five.\n  It is shown that this quinary lattice model is able to describe at\nqualitative level secondary structures of proteins: for this model all\nconformations with minimal energy are combinations of lattice models of\nalpha--helix and beta--strand. Moreover for lattice polymers of the length not\nlonger that 38 monomers we can describe all conformations with minimal energy."
    },
    {
        "anchor": "Active Model H: Scalar Active Matter in a Momentum-Conserving Fluid: We present a continuum theory of self-propelled particles, without alignment\ninteractions, in a momentum-conserving solvent. To address phase separation we\nintroduce a scalar concentration field $\\phi$ with advective-diffusive\ndynamics. Activity creates a contribution\n$\\Sigma_{ij}=-\\zeta((\\partial_i\\phi)(\\partial_j\\phi)-(\\nabla\\phi)^{2}\\delta_{ij}/d)$\nto the deviatoric stress, where $\\zeta$ is odd under time reversal and $d$ is\nthe number of spatial dimensions; this causes an effective interfacial tension\ncontribution that is negative for contractile swimmers. We predict that domain\ngrowth then ceases at a length scale where diffusive coarsening is balanced by\nactive stretching of interfaces, and confirm this numerically. Thus the\ninterplay of activity and hydrodynamics is highly nontrivial, even without\nalignment interactions.",
        "positive": "Non-Affine Shear Modulus in Entangled Networks of Semiflexible Polymers: We investigate the viscoelastic properties of entangled networks of\nsemiflexible polymers. At intermediate time scales the elastic response of\nthese networks to shear deformation is described by the plateau modulus $G$.\nDifferent scaling laws with polymer concentration $c$ have been proposed based\non the assumption that the deformation field is affine on all length scales. We\ndevelop a numerical approach that allows to calculate the modulus via free\nenergy changes for both affine and non-affine deformations. The non-affine\ndeformation field is obtained by a free energy minimization. Our findings allow\nfor a confirmation of a power law $G \\propto c^{7/5} l_p^{-1/5}$ with polymer\nconcentration $c$ and persistence length $l_p$ and furthermore quantify the\nsystematic deviations due to the affinity assumption."
    },
    {
        "anchor": "Buckling in a rotationally invariant spin-elastic model: Scanning tunneling microscopy experiments have revealed an spontaneous\nrippled-to-buckled transition in heated graphene sheets, in absence of any\nmechanical load. Several models relying on a simplified picture of the\ninteraction between elastic and internal, electronic, degrees of freedom have\nbeen proposed to understand this phenomenon. Nevertheless, these models are not\nfully consistent with the classical theory of elasticity, since they do not\npreserve rotational invariance. Herein, we develop and analyse an alternative\nclassical spin-elastic model that preserves rotational invariance while giving\na qualitative account of the rippled-to-buckled transition. By integrating over\nthe internal degrees of freedom, an effective free energy for the elastic modes\nis derived, which only depends on the curvature. Minimisation of this free\nenergy gives rise to the emergence of different mechanical phases, whose\nthermodynamic stability is thoroughly analysed, both analytically and\nnumerically. All phases are characterised by a spatially homogeneous curvature,\nwhich plays the role of the order parameter for the rippled-to-buckled\ntransition, in both the one- and two-dimensional cases. In the latter, our\nfocus is put on the honeycomb lattice, which is representative of actual\ngraphene.",
        "positive": "Characteristics of fluid-fluid displacement in model mixed-wet porous\n  media: patterns, pressures, and scalings: We study the characteristics of fluid-fluid displacement in simple mixed-wet\nporous micromodels numerically using a dynamic pore network model. The porous\nmicromodel consists of distinct water-wet and oil-wet regions, whose fractions\nare systematically varied to yield a variety of displacement patterns over a\nwide range of capillary numbers. We find that the impact of mixed-wettability\nis most prominent at low capillary number, and it depends on the complex\ninterplay between wettability fraction and the intrinsic contact angle of the\nwater-wet regions. For example, the fractal dimension of the displacement\npattern is a monotonically increasing function of wettability fraction in flow\ncells with strongly water-wet clusters, but it becomes non-monotonic with\nrespect to wettability fraction in flow cells with weakly water-wet clusters.\nAdditionally, mixed-wettability also manifests itself in the injection-pressure\nsignature, which exhibits fluctuations especially at low wettability fraction.\nSpecifically, preferential filling of water-wet regions leads to reduced\neffective permeability and higher injection pressure, even at vanishingly small\ncapillary numbers. Finally, we demonstrate that scaling analyses based on a\nweighted average description of the overall wetting state of the mixed-wet\nsystem can effectively capture the variations in observed displacement pattern\nmorphology."
    },
    {
        "anchor": "Characterization of the Drag Force in an Air-Moderated Granular Bed: We measure the torque acting on a rod rotated perpendicular to its axis in a\ngranular bed, through which an upflow of gas is utilized to tune the\nhydrostatic loading between grains. At low rotation rates the torque is\nindependent of speed, but scales quadratically with rod-length and linearly\nwith depth; the proportionality approaches zero linearly as the upflow of gas\nis increased towards a critical value above which the grains are fluidized. At\nhigh rotation rates the torque exhibits quadratic rate- dependence and scales\nas the rod's length to the 4th power. The torque has no dependence on either\ndepth or airflow at these higher rates. A model used to describe the stopping\nforce experienced by a projectile impacting a granular bed can be shown to\npredict these behaviors for our system's geometry, indicating that the same\nmechanics dictate both steady-state and transient drag forces in granular\nsystems, regardless of geometry or material properties of the grains.",
        "positive": "Wetting films on chemically heterogeneous substrates: Based on a microscopic density functional theory we investigate the\nmorphology of thin liquidlike wetting films adsorbed on substrates endowed with\nwell-defined chemical heterogeneities. As paradigmatic cases we focus on a\nsingle chemical step and on a single stripe. In view of applications in\nmicrofluidics the accuracy of guiding liquids by chemical microchannels is\ndiscussed. Finally we give a general prescription of how to investigate\ntheoretically the wetting properties of substrates with arbitrary chemical\nstructures."
    },
    {
        "anchor": "A novel heterogeneous structure formed by a single multiblock copolymer\n  chain: We studied structures formed by a single $(AB)_k$ multiblock copolymer chain,\nin which interaction between A-type beads was purely repulsive, and B-type\nbeads tended to aggregate. We studied how attraction between A-type beads and\nB-type beads affected the structure of the chain. We discovered formation of an\nequilibrium globular structure, which had unique heterogeneous\ncheckerboard-like distribution of contact density. Unlike the structures\nusually formed by a single $(AB)_k$ multiblock copolymer chain, this structure\nhad contact enrichment at the boundaries of A and B blocks. This structure was\nformed by a multiblock copolymer chain, in which B-type beads could form\nmaximum two reversible bonds either with A-type or B-type beads, A-type beads\ncould form maximum one reversible bond with a B-type bead, and interactions\nbetween A-type beads were purely repulsive. Multiblock copolymer chains with\nthis type of intrachain interactions can model structure of chromatin in\nvarious organisms.",
        "positive": "Hysteresis at low Reynolds number: the onset of 2D vortex shedding: Hysteresis has been observed in a study of the transition between laminar\nflow and vortex shedding in a quasi-two dimensional system. The system is a\nvertical, rapidly flowing soap film which is penetrated by a rod oriented\nperpendicular to the film plane. Our experiments show that the transition from\nlaminar flow to a periodic K\\'arm\\'an vortex street can be hysteretic, i.e.\nvortices can survive at velocities lower than the velocity needed to generate\nthem."
    },
    {
        "anchor": "Viscosity control of the dynamic self-assembly in ferromagnetic\n  suspensions: Recent studies of dynamic self-assembly in ferromagnetic colloids suspended\nin liquid-air or liquid-liquid interfaces revealed a rich variety of dynamic\nstructures ranging from linear snakes to axisymmetric asters, which exhibit\nnovel morphology of the magnetic ordering accompanied by large-scale\nhydrodynamic flows. Based on controlled experiments and first principle theory,\nwe argue that the transition from snakes to asters is governed by the viscosity\nof the suspending liquid where less viscous liquids favor snakes and more\nviscous, asters. By obtaining analytic solutions of the time-averaged\nNavier-Stokes equations, we gain insights into the role of mean hydrodynamic\nflows and an overall balance of forces governing the self-assembly. Our results\nillustrate that the viscosity can be used to control the outcome of the dynamic\nself-assembly in magnetic colloidal suspensions.",
        "positive": "Collagen-DNA macromolecular complex study by the proton magnetic\n  relaxation method: Comparing the obtained experimental data for the proton magnetic relaxation\nwith the microcalorimetric ones it is concluded that in the aqueous solution of\ncollagen + DNA at temperatures below 35oC a stable molecular complex\ncollagen-DNA is formed prohibiting the formation of the hydration cover of\ncollagen which is manifested by the almost two times decrease of hydration. At\ntemperatures (25-45)oC the disruption of complex and melting of triple helix of\ncollagen takes place. Starting from temperature 45oC up to 90oC hydration\nvalues, calculated from experimental data on proton relaxation for solution\nand, theoretical values calculated for the solution coincide speaking of the\nfact that macromolecules in the solution are not practically interacting with\neach other and not influencing the creation of each others hydration covers."
    },
    {
        "anchor": "How do polymers stretch in capillary-driven extensional flows?: Measurements of the capillary-driven thinning and breakup of fluid filaments\nare widely used to extract extensional rheological properties of complex\nmaterials. For viscoelastic (e.g., polymeric) fluids, the determination of the\nlongest relaxation time depends on several assumptions concerning the polymeric\nresponse to the flow that are derived from constitutive models. Our capillary\nthinning experiments using polymeric fluids with a wide range of extensibility,\nsuggest that these assumptions are likely only valid for highly extensible\npolymers but do not hold in general. For polymers with relatively low\nextensibility, such as polyectrolytes in salt-free media, conventional\nextrapolation of the longest relaxation time from capillary thinning techniques\nleads to a significant underestimation.",
        "positive": "Diffusion of an Enzyme: the Role of Fluctuation-Induced Hydrodynamic\n  Coupling: The effect of conformational fluctuations of modular macromolecules, such as\nenzymes, on their diffusion properties is addressed using a simple generic\nmodel of an asymmetric dumbbell made of two hydrodynamically coupled subunits.\nIt is shown that equilibrium fluctuations can lead to an interplay between the\ninternal and the external degrees of freedom and give rise to negative\ncontributions to the overall diffusion coefficient. Considering that this model\nenzyme explores a mechanochemical cycle, we show how substrate binding and\nunbinding affects its internal fluctuations, and how this can result in an\nenhancement of the overall diffusion coefficient of the molecule. These\ntheoretical predictions are successfully confronted with recent measurements of\nenzyme diffusion in dilute conditions using fluorescence correlation\nspectroscopy."
    },
    {
        "anchor": "Protein folding on rugged energy landscapes: Conformational diffusion on\n  fractal networks: We employ simulations of model proteins to study folding on rugged energy\nlandscapes. We construct ``first-passage'' networks as the system transitions\nfrom unfolded to native states. The nodes and bonds in these networks\ncorrespond to basins and transitions between them in the energy landscape. We\nfind power-laws between the folding time and number of nodes and bonds. We show\nthat these scalings are determined by the fractal properties of first-passage\nnetworks. Reliable folding is possible in systems with rugged energy landscapes\nbecause first passage networks have small fractal dimension.",
        "positive": "Structural correlations in highly asymmetric binary charged colloidal\n  mixtures: We explore structural correlations of strongly asymmetric mixtures of binary\ncharged colloids within the primitive model of electrolytes considering large\ncharge and size ratios of 10 and higher. Using computer simulations with\nexplicit microions, we obtain the partial pair correlation functions between\nthe like-charged colloidal macroions. Interestingly the big-small correlation\npeak amplitude is smaller than that of the big-big and small-small macroion\ncorrelation peaks, which is unfamiliar for additive repulsive interactions.\nExtracting optimal effective microion-averaged pair interactions between the\nmacroions, we find that on top of non-additive Yukawa-like repulsions an\nadditional shifted Gaussian attractive potential between the small macroions is\nneeded to accurately reproduce their correct pair correlations. For small\nCoulomb couplings, the behavior is reproduced in a coarse-grained theory with\nmicroion-averaged effective interactions between the macroions. However, the\naccuracy of the theory deteriorates with increasing Coulomb coupling. We\nemphasize the relevance of entropic interactions exerted by the microions on\nthe macroions. Our results are experimentally verifiable in binary mixtures of\nmicron-sized colloids and like-charge nanoparticles"
    },
    {
        "anchor": "Controlling the shape and topology of two-component colloidal membranes: Changes in the geometry and topology of self-assembled membranes underlie\ndiverse processes across cellular biology and engineering. Similar to lipid\nbilayers, monolayer colloidal membranes have in-plane fluid-like dynamics and\nout-of-plane bending elasticity. Their open edges and micron length scale\nprovide a tractable system to study the equilibrium energetics and dynamic\npathways of membrane assembly and reconfiguration. Here, we find that doping\ncolloidal membranes with short miscible rods transforms disk-shaped membranes\ninto saddle-shaped surfaces with complex edge structures. The saddle-shaped\nmembranes are well-approximated by Enneper's minimal surfaces. Theoretical\nmodeling demonstrates that their formation is driven by increasing positive\nGaussian modulus, which in turn is controlled by the fraction of short rods.\nFurther coalescence of saddle-shaped surfaces leads to diverse topologically\ndistinct structures, including catenoids, tri-noids, four-noids, and higher\norder structures. At long time scales, we observe the formation of a\nsystem-spanning, sponge-like phase. The unique features of colloidal membranes\nreveal the topological transformations that accompany coalescence pathways in\nreal time. We enhance the functionality of these membranes by making their\nshape responsive to external stimuli. Our results demonstrate a novel pathway\ntowards control of thin elastic sheets' shape and topology -- a pathway driven\nby the emergent elasticity induced by compositional heterogeneity.",
        "positive": "A simple model for the small-strain behaviour of soils: The constitutive equation discussed in this note eliminates some defects of\nlinear elasticity in the description of the small-strain behaviour of soils. It\nis capable of representing volume changes in pure shear and different values of\nbulk modulus in compression and expansion. The new equation provides a simple\ndescription of soil behaviour at small strains in that it produces linear\nstress-strain relations that can approximate the initial part of experimental\nstress-strain curves."
    },
    {
        "anchor": "Evaporation of a thin film: diffusion of the vapour and Marangoni\n  instabilities: The stability of an evaporating thin liquid film on a solid substrate is\ninvestigated within lubrication theory. The heat flux due to evaporation\ninduces thermal gradients; the generated Marangoni stresses are accounted for.\nAssuming the gas phase at rest, the dynamics of the vapour reduces to\ndiffusion. The boundary condition at the interface couples transfer from the\nliquid to its vapour and diffusion flux. A non-local lubrication equation is\nobtained; this non-local nature comes from the Laplace equation associated with\nquasi-static diffusion. The linear stability of a flat film is studied in this\ngeneral framework. The subsequent analysis is restricted to moderately thick\nfilms for which it is shown that evaporation is diffusion limited and that the\ngas phase is saturated in vapour in the vicinity of the interface. The\nstability depends only on two control parameters, the capillary and Marangoni\nnumbers. The Marangoni effect is destabilising whereas capillarity and\nevaporation are stabilising processes. The results of the linear stability\nanalysis are compared with the experiments of Poulard et al (2003) performed in\na different geometry. In order to study the resulting patterns, the amplitude\nequation is obtained through a systematic multiple-scale expansion. The\nevaporation rate is needed and is computed perturbatively by solving the\nLaplace problem for the diffusion of vapour. The bifurcation from the flat\nstate is found to be a supercritical transition. Moreover, it appears that the\nnon-local nature of the diffusion problem unusually affects the amplitude\nequation.",
        "positive": "A microscopic theory for discontinuous shear thickening of frictional\n  granular materials: We extend a recent theory for the rheology of frictionless granular materials\n[K. Suzuki and H. Hayakawa, Phys. Rev. Lett. 2015, 115, 098001] to the case of\nfrictional disks in two dimensions. Employing a frictional contact model for\nmolecular dynamics simulations, we derive difference equations of the shear\nstress, the granular temperature, and the spin temperature from the generalized\nGreen-Kubo formula, where all the terms are given by microscopic expressions.\nThe numerical solutions of the difference equations not only describe the flow\ncurve, but also reproduce the hysteresis of shear stress, which can be the\nsignature of discontinuous shear thickening of frictional disks."
    },
    {
        "anchor": "A simple microscopic model for the dynamics of adhesive failure: We consider a microscopic model for the failure of soft adhesives in tension\nbased on ideas of bond rupture under dynamic loading. Focusing on adhesive\nfailure under loading at constant velocity, we demonstrate that bi-modal curves\nof stress against strain may occur due to effects of finite polymer chain or\nbond length and characterise the loading conditions under which such bi-modal\nbehaviour is observed. The results of this analysis are in qualitative\nagreement with experiments performed on unconfined adhesives in which failure\ndoes not occur by cavitation.",
        "positive": "Statistics of jamming in the discharge of a 2-D Silo: Jamming and avalanche statistics are studied in a simulation of the discharge\nof a polydisperse ensemble of disks from a 2-D silo. Exponential distributions\nare found for the avalanche sizes for all sizes of the exit opening, in\nagreement with reported experiments. The average avalanche size grows quite\nfast with the size of the exit opening. Data for this growth agree better with\na critical divergence with a large critical exponent, as reported for 3-D\nexperiments, than with the exponential growth reported for 2-D experiments."
    },
    {
        "anchor": "Adhesive wear regimes on rough surfaces and interaction of\n  micro-contacts: We develop an analytical model of adhesive wear between two unlubricated\nrough surfaces, forming micro-contacts under normal load. The model is based on\nan energy balance and a crack initiation criteria. We apply the model to the\nproblem of self-affine rough surfaces under normal load, which we solve using\nthe boundary element method. We discuss how self-affinity of the surface\nroughness, and the complex morphology of the micro-contacts that emerge for a\ngiven contact pressure, challenge the definition of contact junctions. Indeed,\nin the context of adhesive wear, we show that elastic interactions between\nnearby micro-contacts can lead to wear particles whose volumes enclose the\nconvex hull of these micro-contacts. We thereby obtain a wear map describing\nthe instantaneous produced wear volume as a function of material properties,\nroughness parameters and loading conditions. Three distinct wear regimes can be\nidentified in the wear map. In particular, the model predicts the emergence of\na severe wear regime above a critical contact pressure, when interactions\nbetween micro-contacts are favored.",
        "positive": "Electrostatically induced undulations of lamellar DNA-lipid complexes: We consider DNA-cationic lipid complexes that form lamellar stacks of lipid\nbilayers with parallel DNA strands intercalated in between. We calculate the\nelectrostatically induced elastic deformations of the lipid bilayers. It is\nfound that the membranes undulate with a periodicity that is set by the DNA\ninteraxial distance. As a consequence the lamellar repeat distance changes\nresulting in a swelling or compression of the lamellar stack. Such undulations\nmay be responsible for the intermembrane coupling between DNA strands in\ndifferent layers as it is observed experimentally."
    },
    {
        "anchor": "Emergent collective properties of many-motor systems in one dimension: Along a microtubule, certain active motors propel themselves in one direction\nwhereas others propel themselves in the opposite direction. For example, the\ncargo transporting motor proteins dynein and kinesin propel themselves towards\nthe so-called plus- and minus-ends of the microtubule, respectively, and in so\ndoing are able to pass one another, but not without interacting. We address the\nemergent collective behavior of systems composed of many motors, some\npropelling towards the plus-end and others propelling towards the minus-end. To\ndo this, we used an analogy between this strongly interacting,\nfar-from-equilibrium, classical stochastic many-motor system and a certain\nquantum-mechanical many-body system evolving in imaginary time. We apply\nwell-known methods from quantum many-body theory, including self-consistent\nmean-field theory and bosonization, to shed light on phenomena exhibited by the\nmany-motor system such as structure formation and the dynamics of collective\nmodes at low-frequencies and long-wavelengths. In particular, via the bosonized\ndescription we find analogs of chiral Luttinger liquids, as well as a\nqualitative transition in the nature of the low-frequency modes---from\npropagating to purely dissipative---controlled by density and interaction\nstrength.",
        "positive": "Gel rupture in a dynamic environment: Hydrogels have had a profound impact in the fields of tissue engineering,\ndrug delivery, and materials science as a whole. Due to the network\narchitecture of these materials, imbibement with water often results in uniform\nswelling and isotropic expansion which scales with the degree of cross-linking.\nHowever, the development of internal stresses during swelling can have dramatic\nconsequences, leading to surface instabilities as well as rupture or bursting\nevents. To better understand hydrogel behavior, macroscopic mechanical\ncharacterization techniques (e.g.\\ tensile testing, rheometry) are often used,\nhowever most commonly these techniques are employed on samples that are in two\ndistinct states: (1) unswollen and without any solvent, or (2) in an\nequilibrium swelling state where the maximum amount of water has been imbibed.\nRarely is the dynamic process of swelling studied, especially in samples where\nrupture or failure events are observed. To address this gap, here we focus on\nrupture events in poly(ethylene glycol)-based networks that occur in response\nto swelling with water. Rupture events were visualized using high-speed\nimaging, and the influence of swelling on material properties was characterized\nusing dynamic mechanical analysis. We find that rupture events follow a\nthree-stage process that includes a waiting period, a slow fracture period, and\na final stage in which a rapid increase in the velocity of crack propagation is\nobserved. We describe this fracture behavior based on changes in material\nproperties that occur during swelling, and highlight how this rupture behavior\ncan be controlled by straight-forward modifications to the hydrogel network\nstructure."
    },
    {
        "anchor": "Low Temperature Electronic Transport through Macromolecules and\n  Characteristics of Intramolecular Electron Transfer: A theory of electronic transport through molecular wires is applied to\nanalyze characteristics of a long-range electron transfer (ET) through\nmolecular bridges in macromolecules with complex donor/acceptor subsystems.\nAssuming a coherent electron tunneling through the bridge to be the predominant\nmechanism of ET at low temperatures it is shown that low temperature\ncurrent-voltage curves can exhibit a step-like structure, which contains\ninformation concerning intrinsic features of ET processes such as the effect of\ndonor/acceptor coupling to the bridge and primary pathways of electrons\ntunneling through the bridge. By contacting the proposed theoretical analysis\nwith such experimental data a variety of valuable characteristics of long-range\nintramolecular ET can be identified. Analytical and numerical results are\npresented. Using the Buttiker dephasing model within the scattering matrix\nformalism we analyze dephasing effects, and we show that these effects could be\nreduced enough to allow the structure of the electron transmission function to\nbe exposed in the experiments on the electronic transport through\nmacromolecules.",
        "positive": "Bridging from particle to macroscopic scales in uniaxial magnetic gels: Connecting the different length scales of characterization is an important,\nbut often very tedious task for soft matter systems. Here we carry out such a\nprocedure for the theoretical description of anisotropic uniaxial magnetic\ngels. The so-far undetermined material parameters in a symmetry-based\nmacroscopic hydrodynamic-like description are determined starting from a\nsimplified mesoscopic particle-resolved model. This mesoscopic approach\nconsiders chain-like aggregates of magnetic particles embedded in an elastic\nmatrix. Our procedure provides an illustrative background to the formal\nsymmetry-based macroscopic description. There are presently other activities to\nconnect such mesoscopic models as ours with more microscopic polymer-resolved\napproaches; together with these activities, our study complements a first\nattempt of scale-bridging from the microscopic to the macroscopic level in the\ncharacterization of magnetic gels."
    },
    {
        "anchor": "Generic morphologies of viscoelastic dewetting fronts: A simple model is put forward which accounts for the occurrence of certain\ngeneric dewetting morphologies in thin liquid coatings. It demonstrates that by\ntaking into account the elastic properties of the coating, a morphological\nphase diagram may be derived which describes the observed structures of\ndewetting fronts. It is demonstrated that dewetting morphologies may also serve\nto determine nanoscale rheological properties of liquids.",
        "positive": "Shear-driven size segregation of granular materials: modeling and\n  experiment: Granular materials segregate by size under shear, and the ability to\nquantitatively predict the time required to achieve complete segregation is a\nkey test of our understanding of the segregation process. In this paper, we\napply the Gray-Thornton model of segregation (developed for linear shear\nprofiles) to a granular flow with an exponential profile, and evaluate its\nability to describe the observed segregation dynamics. Our experiment is\nconducted in an annular Couette cell with a moving lower boundary. The granular\nmaterial is initially prepared in an unstable configuration with a layer of\nsmall particles above a layer of large particles. Under shear, the sample mixes\nand then re-segregates so that the large particles are located in the top half\nof the system in the final state. During this segregation process, we measure\nthe velocity profile and use the resulting exponential fit as input parameters\nto the model. To make a direct comparison between the continuum model and the\nobserved segregation dynamics, we locally map the measured height of the\nexperimental sample (which indicates the degree of segregation) to the local\npacking density. We observe that the model successfully captures the presence\nof a fast mixing process and relatively slower re-segregation process, but the\nmodel predicts a finite re-segregation time, while in the experiment\nre-segregation occurs only exponentially in time."
    },
    {
        "anchor": "The role of weak charging in metastable colloidal clusters: We study metastable clusters in a colloidal system with competing\ninteractions. A short-ranged polymer-induced attraction drives clustering,\nwhile a weak, long-ranged electrostatic repulsion prevents extensive\naggregation. We compare experimental yields of cluster structures expected from\ntheory, which assumes simple addition of the competing isotropic interactions.\nFor clusters of size $4\\leq m\\leq6$, the yield is significantly less than that\nexpected. We attribute this to an anisotropic self-organized surface charge\ndistribution linked to the cluster symmetry: non-additivity of electrostatic\nrepulsion and polymer-induced attraction. 7-membered clusters have a clear\noptimal yield of the expected pentagonal bipyramid structure as a function of\nstrength of the attractive interaction.",
        "positive": "A simple, general criterion for onset of disclination disorder on curved\n  surfaces: Determining the positions of lattice defects on elastic surfaces with\nGaussian curvature is a non-trivial task of mechanical energy optimization,\nparticularly for surfaces with boundaries. We introduce a simple way to predict\nthe onset of disclination disorder from the shape of bounded surfaces. The\ncriterion fixes the value of a weighted integral Gaussian curvature to a\nuniversal constant and proves accurate across a great variety of shapes, even\nwhen previously suggested criteria fail. It is an easy avenue to improved\nunderstanding of the limitations to crystalline order in many materials."
    },
    {
        "anchor": "Creep dynamics of athermal amorphous materials: a mesoscopic approach: Yield stress fluids display complex dynamics, in particular when driven into\nthe transient regime between the solid and the flowing state. Inspired by creep\nexperiments on dense amorphous materials, we implement mesocale elasto-plastic\ndescriptions to analyze such transient dynamics in athermal systems. Both our\nmean-field and space-dependent approaches consistently reproduce the typical\nexperimental strain rate responses to different applied steps in stress.\nMoreover, they allow us to understand basic processes involved in the strain\nrate slowing down (creep) and the strain rate acceleration (fluidization)\nphases. The fluidization time increases in a power-law fashion as the applied\nexternal stress approaches a static yield stress. This stress value is related\nto the stress over-shoot in shear start-up experiments, and it is known to\ndepend on sample preparation and age. By calculating correlations of the\naccumulated plasticity in the spatially resolved model, we reveal different\nmodes of cooperative motion during the creep dynamics.",
        "positive": "Slowing down of water dynamics in disaccharide aqueous solutions: The dynamics of water in aqueous solutions of three homologous disaccharides,\nnamely trehalose, maltose and sucrose, has been analyzed by means of molecular\ndynamics simulations in the 0-66 wt % concentration range. The low-frequency\nvibrational densities of states (VDOS) of water were compared with the\nsusceptibilities chi\" of 0-40 wt % solutions of trehalose in D2O obtained from\ncomplementary Raman scattering experiments. Both reveal that sugars\nsignificantly stiffen the local environments experienced by water. Accordingly,\nits translational diffusion coefficient decreases when the sugar concentration\nincreases, as a result of an increase of water-water hydrogen bonds lifetimes\nand of the corresponding activation energies. This induced slowing down of\nwater dynamics, ascribed to the numerous hydrogen bonds that sugars form with\nwater, is strongly amplified at concentrations above 40 wt % by the percolation\nof the hydrogen bond network of sugars, and may partially explain their\nwell-known stabilizing effect on proteins in aqueous solutions."
    },
    {
        "anchor": "Electrostatic Force Between Two Colloidal Spheres: In this dissertation we analyzed the double-layer force interaction between\ntwo dielectric charged colloidal spheres of different radii immersed in a\nsolution of ions in water and in thermal equilibrium. In the limit of low\nelectrostatic potential the interaction is governed by the Linearized\nPoisson-Boltzmann Equation (LPBE). We obtained an analytical solution from the\nLPBE for the electrostatic interaction via multipole expansion, considering a\nuniform and fixed surface charge density on the spheres. A code in the\nMathematica platform was developed, allowing us to calculate the force between\nthe spheres as a function of their separation. In order to validate the code,\nwe compared our numerical results with the analytical ones in the limits of\nLinear Superposition Approximation (LSA) (valid for sphere separations much\ngreater than the Debye length) and Proximity Force Approximation (PFA) (valid\nfor sphere separations and Debye length much smaller than the radii of the\nspheres).",
        "positive": "Size dependent motion of nanodroplets on chemical steps: Nanodroplets on chemically structured substrates move under the action of\ndisjoining pressure induced forces. A detailed analysis of them shows that even\nin the absence of long-ranged lateral variations of the effective interface\npotential, already the fact, that due their small size nano-droplets do not\nsample the disjoining pressure at all distances from the substrate, can lead to\ndroplet motion towards the less wettable part of the substrate, i.e., in the\ndirection opposite to the one expected on the basis of macroscopic wettability\nconsiderations."
    },
    {
        "anchor": "Nonlinear thermal control in an N-terminal junction: We demonstrate control over heat flow in an N-terminal molecular junction.\nUsing simple model Hamiltonians we show that the heat current through two\nterminals can be tuned, switched, and amplified, by the temperature and\ncoupling parameters of external gating reservoirs. We discuss two models: A\nfully harmonic system, and a model incorporating anharmonic interactions. For\nboth models the control reservoirs induce thermal fluctuations of the\ntransition elements between molecular vibrational states. We find that a fully\nharmonic model does not show any controllability, while for an anharmonic\nsystem the conduction properties of the junction strongly depend on the\nparameters of the gates. Realizations of the model system within nanodevices\nand macromolecules are discussed.",
        "positive": "Temperature distribution in driven granular mixtures does not depend on\n  mechanism of energy dissipation: We study analytically and numerically the distribution of granular\ntemperatures in granular mixtures for different dissipation mechanisms of\ninelastic inter-particle collisions. Both driven and force-free systems are\nanalyzed. We demonstrate that the simplified model of a constant restitution\ncoefficient fails to predict even qualitatively a granular temperature\ndistribution in a homogeneous cooling state. At the same time we reveal for\ndriven systems a stunning result -- the distribution of temperatures in\ngranular mixtures is universal. That is, it does not depend on a particular\ndissipation mechanism of inter-particles collisions, provided the size\ndistributions of particles is steep enough. The results of the analytic theory\nare compared with simulation results obtained by the direct simulation Monte\nCarlo (DSMC). The agreement between the theory and simulations is perfect. The\nreported results may have important consequences for fundamental science as\nwell as for numerous application, e.g. for the experimental modelling in a lab\nof natural processes."
    },
    {
        "anchor": "Phase behavior of the Lattice Restricted Primitive Model with\n  nearest-neighbor exclusion: The global phase behavior of the lattice restricted primitive model with\nnearest neighbor exclusion has been studied by grand canonical Monte Carlo\nsimulations. The phase diagram is dominated by a fluid (or charge-disordered\nsolid) to charge-ordered solid transition that terminates at the maximum\ndensity, $\\rho^*_{max}=\\sqrt2$ and reduced temperature $T^*\\approx0.29$. At\nthat point, there is a first-order phase transition between two phases of the\nsame density, one charge-ordered and the other charge-disordered. The\nliquid-vapor transition for the model is metastable, lying entirely within the\nfluid-solid phase envelope.",
        "positive": "Erythrocyte sedimentation: Fracture and collapse of a\n  high-volume-fraction soft-colloid gel: The erythrocyte sedimentation rate is one of the oldest medical diagnostic\nmethods whose physical mechanisms remain debatable up to date. Using both light\nmicroscopy and mesoscale cell-level simulations, we show that erythrocytes form\na soft-colloid gel. Furthermore, the high volume fraction of erythrocytes,\ntheir deformability, and weak attraction lead to unusual properties of this\ngel. A theoretical model for the gravitational collapse is developed, whose\npredictions are in agreement with detailed macroscopic measurements of the\ninterface velocity."
    },
    {
        "anchor": "Molecular simulation of 2-dimensional microphase separation of\n  single-component homopolymers grafted onto a planar substrate: The structural phase behavior of polymer brushes, single-component linear\nhomopolymers grafted onto a planar substrate, is studied using the molecular\nMonte Carlo method in 3 dimensions. When simulation parameters of the system\nare set in regions of macrophase separation of solution for the corresponding\nnon-grafted homopolymers, the grafted polymers also prefer segregation.\nHowever, macrophase separation is disallowed due to the spatially-fixed\ngrafting points of the polymers. Such constraints on the grafting are similar\nto connecting points between blocks of non-grafted diblock copolymers at the\nmicrophase separation in the melt state. This results in \"microphase\nseparation\" of the homopolymer brush in the lateral direction of the substrate.\nHere we extensively search the parameter space and reveal various lateral\ndomain patterns that are similar to those found in diblock copolymer melts at\nmicrophase separation.",
        "positive": "A Unifying Framework to Quantify the Effects of Substrate Interactions,\n  Stiffness, and Roughness on the Dynamics of Thin Supported Polymer Films: Changes in the dynamics of supported polymer films in comparison to bulk\nmaterials involve a complex convolution of effects, such as substrate\ninteractions, roughness and compliance, in addition to film thickness. We\nconsider molecular dynamics simulations of substrate-supported, coarse-grained\npolymer films where these parameters are tuned separately to determine how each\nof these variables influence the molecular dynamics of thin polymer films. We\nfind that all these variables significantly influence the film dynamics,\nleading to a seemingly intractable degree of complexity in describing these\nchanges. However, by considering how these constraining variables influence\nstring-like collective motion within the film, we show that all our\nobservations can be understood in a unified and quantitative way. More\nspecifically, the string model for glass-forming liquids implies that the\nchanges in the structural relaxation of these films are governed by the changes\nin the average length of string-like cooperative motions and this model is\nconfirmed under all conditions considered in our simulations. Ultimately, these\nchanges are parameterized in terms of just the activation enthalpy and entropy\nfor molecular organization, which have predictable dependences on substrate\nproperties and film thickness, offering a promising approach for the rational\ndesign of film properties."
    },
    {
        "anchor": "Three-Body Interactions of Lipid Membrane-Deforming Colloidal Spheres: Many cell functions require a concerted effort from multiple membrane\nproteins, for example, for signaling, cell division, and endocytosis. One\ncontribution to their successful self-organization stems from the membrane\ndeformations that these proteins induce. While the pairwise interaction\npotential of two membrane deforming spheres has recently been measured,\nmembrane-deformation induced interactions have been predicted to be\nnon-additive and hence their collective behavior cannot be deduced from this\nmeasurement. We here employ a colloidal model system consisting of adhesive\nspheres and giant unilamellar vesicles to test these predictions by measuring\nthe interaction potential of the simplest case of three membrane-deforming\nspherical particles. We quantify their interactions and arrangements and for\nthe first time experimentally confirm and quantify the non-additive nature of\nmembrane-deformation induced interactions. We furthermore conclude that there\nexist two favorable configurations on the membrane: (1) a linear, and (2) a\ntriangular arrangement of the three spheres. Using Monte Carlo simulation we\ncorroborate the experimentally observed energy minima and identify a lowering\nof the membrane deformation as the cause for the observed configurations. The\nhigh symmetry of the preferred arrangements for three particles suggests that\narrangements of many membrane-deforming objects might follow simple rules.",
        "positive": "Elastic colloidal monopoles and reconfigurable self-assembly in liquid\n  crystals: Monopole-like electrostatic interactions are ubiquitous in biology and\ncondensed matter, but they are often screened by counter-ions and cannot be\nswitched from attractive to repulsive. In colloidal science, where the prime\ngoal is to develop colloidal particles that mimic and exceed the diversity and\nlength-scales of atomic and molecular assembly, electrostatically charged\nparticles cannot change the sign of their surface charge or transform from\nmonopoles to higher-order multipoles. In liquid-crystal colloids, elastic\ninteractions between particles arise to minimize the free energy associated\nwith elastic distortions in the long-range alignment of rod-like molecules\naround the particles. In dipolar, quadrupolar and hexadecapolar nematic\ncolloids, the symmetries of such elastic distortions mimic both electrostatic\nmultipoles and the outmost occupied electron shells of atoms. Electric and\nmagnetic switching, spontaneous transformations and optical control of elastic\nmultipoles, as well as their interactions with topological defects and surface\nboundary conditions, have been demonstrated in such colloids. However, it has\nlong been understood that elastic monopoles should relax to uniform or\nhigher-order multipole states because of the elastic torques that they induce.\nHere we develop nematic colloids with strong elastic monopole moments and with\nelastic torques balanced by optical torques exerted by ambient light. We\ndemonstrate the monopole-to-quadrupole reconfiguration of these colloidal\nparticles by unstructured light, which resembles the driving of atoms between\nthe ground state and various excited states. We show that the sign of the\nelastic monopoles can be switched, and that like-charged monopoles attract\nwhereas oppositely charged ones repel, unlike in electrostatics. We also\ndemonstrate the out-of-equilibrium dynamic assembly of these colloidal\nparticles."
    },
    {
        "anchor": "Adsorption time scales of cluster-forming systems: A microscopic model of adsorption in cluster forming systems with competing\ninteraction is considered. The adsorption process is described by the master\nequation and modelled by a kinetic Monte Carlo method. The evolution of the\nparticle concentration and interaction energy during the adsorption of\nparticles on a plane triangular lattice is investigated. The simulation results\nshow a diverse behavior of the system time evolution depending on the\ntemperature and chemical potential and finally on the formation of clusters in\nthe system. The characteristic relaxation times of adsorption vary in several\norders of magnitude depending on the thermodynamic parameters of the final\nequilibrium state of the adsorbate. A very fast adsorption of particles is\nobserved for highly ordered adsorbate equilibrium states.",
        "positive": "Phase diagrams of polymer-containing liquid mixtures with a\n  theory-embedded neural network: We develop a deep neural network (DNN) that accounts for the phase behaviors\nof polymer-containing liquid mixtures. The key component in the DNN consists of\na theory-embedded layer that captures the characteristic features of the phase\nbehavior via coarse-grained mean-field theory and scaling laws and\nsubstantially enhances the accuracy of the DNN. Moreover, this layer enables us\nto reduce the size of the DNN for the phase diagrams of the mixtures. This\nstudy also presents the predictive power of the DNN for the phase behaviors of\npolymer solutions and salt-free and salt-doped diblock copolymer melts."
    },
    {
        "anchor": "Universal scaling for disordered viscoelastic matter near the onset of\n  rigidity: The onset of rigidity in interacting liquids, as they undergo a transition to\na disordered solid, is associated with a rearrangement of the low-frequency\nvibrational spectrum. In this letter, we derive scaling forms for the singular\ndynamical response of disordered viscoelastic networks near both jamming and\nrigidity percolation. Using effective-medium theory, we extract critical\nexponents, invariant scaling combinations and analytical formulas for universal\nscaling functions near these transitions. Our scaling forms describe the\nbehavior in space and time near the various onsets of rigidity, for rigid and\nfloppy phases and the crossover region, including diverging length and time\nscales at the transitions.",
        "positive": "Swinging and tumbling of multicomponent vesicles in flow: Biological membranes are host to proteins and molecules which may form\ndomain-like structures resulting in spatially-varying material properties.\nVesicles with such heterogeneous membranes can exhibit intricate shapes at\nequilibrium and rich dynamics when placed into a flow. Under the assumption of\nsmall deformations we develop a reduced order model to describe the\nfluid-structure interaction between a viscous background shear flow and an\ninextensible membrane in two dimensions with spatially varying bending\nstiffness and spontaneous curvature. Material property variations of a critical\nmagnitude, relative to the flow rate and internal/external viscosity contrast,\ncan set off a qualitative change in the vesicle dynamics. A membrane of nearly\nconstant bending stiffness or spontaneous curvature undergoes a small amplitude\nswinging motion (which includes tangential tank-treading), while for large\nenough material variations the dynamics pass through a regime featuring\ntumbling and periodic phase-lagging of the membrane material, and ultimately\nfor very large material variation to a rigid body tumbling behavior. Distinct\ndifferences are found for even and odd spatial modes of domain distribution.\nFull numerical simulations are used to probe the theoretical predictions, which\nappear valid even when studying substantially deformed membranes."
    },
    {
        "anchor": "Crosslinker energy landscape effects on dynamic mechanical properties of\n  ideal polymer hydrogels: Reversible crosslinkers can enable several desirable mechanical properties,\nsuch as improved toughness and self-healing, when incorporated in polymer\nnetworks for bioengineering and structural applications. In this work, we\nperformed coarse-grained molecular dynamics to investigate the effect of the\nenergy landscape of reversible crosslinkers on the dynamic mechanical\nproperties of crosslinked polymer network hydrogels. We report that, for an\nideal network, the energy potential of the crosslinker interaction drives the\nviscosity of the network, where a stronger potential results in a higher\nviscosity. Additional topographical analyses reveal a mechanistic understanding\nof the structural rearrangement of the network as it deforms and indicate that\nas the number of defects increases in the network, the viscosity of the network\nincreases. As an important validation for the relationship between the energy\nlandscape of a crosslinker chemistry and the resulting dynamic mechanical\nproperties of a crosslinked ideal network hydrogel, this work enhances our\nunderstanding of deformation mechanisms in polymer networks that cannot easily\nbe revealed by experiment and reveals design ideas that can lead to better\nperformance of the polymer network at the macroscale.",
        "positive": "Force Mobilization and Generalized Isostaticity in Jammed Packings of\n  Frictional Grains: We show that in slowly generated 2d packings of frictional spheres, a\nsignificant fraction of the friction forces lies at the Coulomb threshold - for\nsmall pressure p and friction coefficient mu, about half of the contacts.\nInterpreting these contacts as constrained leads to a generalized concept of\nisostaticity, which relates the maximal fraction of fully mobilized contacts\nand contact number. For p->0, our frictional packings approximately satisfy\nthis relation over the full range of mu. This is in agreement with a previous\nconjecture that gently built packings should be marginal solids at jamming. In\naddition, the contact numbers and packing densities scale with both p and mu."
    },
    {
        "anchor": "Crowding of interacting fluid particles in porous media through\n  molecular dynamics: breakdown of universality for soft interactions: Molecular dynamics simulations of interacting soft disks confined in a\nheterogeneous quenched matrix of soft obstacles show dynamics which is\nfundamentally different from that of hard disks. The interactions between the\ndisks can enhance transport when their density is increased, as disks\ncooperatively help each other over the finite energy barriers in the matrix.\nThe system exhibits a transition from a diffusive to a localized state but the\ntransition is strongly rounded. Effective exponents in the mean-squared\ndisplacement can be observed over three decades in time but depend on the\ndensity of the disks and do not correspond to asymptotic behavior in the\nvicinity of a critical point, thus showing that it is incorrect to relate them\nto the critical exponents in the Lorentz model scenario. The soft interactions\nare therefore responsible for a breakdown of the universality of the dynamics.",
        "positive": "Alignment and Nonlinear Elasticity in Biopolymer Gels: We present a Landau type theory for the non-linear elasticity of biopolymer\ngels with a part of the order parameter describing induced nematic order of\nfibers in the gel. We attribute the non-linear elastic behavior of these\nmaterials to fiber alignment induced by strain. We suggest an application to\ncontact guidance of cell motility in tissue. We compare our theory to\nsimulation of a disordered lattice model for biopolymers. We treat homogeneous\ndeformations such as simple shear, hydrostatic expansion, and simple extension,\nand obtain good agreement between theory and simulation. We also consider a\nlocalized perturbation which is a simple model for a contracting cell in a\nmedium."
    },
    {
        "anchor": "Entropic effects in the self-assembly of open lattices from patchy\n  particles: Open lattices are characterized by low volume-fraction arrangements of\nbuilding blocks, low coordination number, and open spaces between building\nblocks. The self-assembly of these lattices faces the challenge of mechanical\ninstability due to their open structures. We theoretically investigate the\nstabilizing effects of entropy in the self-assembly of open lattices from\npatchy particles. A preliminary account of these findings and their comparison\nto experiment was presented recently [X. Mao, Q. Chen, S. Granick, \\textit{Nat.\nMater.}, \\textbf{12}, 217 (2013)]. We found that rotational entropy of patchy\nparticles can provide mechanical stability to open lattices, whereas\nvibrational entropy of patchy particles can lower the free energy of open\nlattices and thus enables the selection of open lattices verses close-packed\nlattices which have the same potential energy. These effects open the door to\nsignificant simplifications of possible future designs of patchy-particles for\nopen-lattice self-assembly.",
        "positive": "Polar coordinate lattice Boltzmann modeling of compressible flows: We present a polar coordinate lattice Boltzmann kinetic model for\ncompressible flows. A method to recover the continuum distribution function\nfrom the discrete distribution function is indicated. Within the model, a\nhybrid scheme being similar to, but different from, the operator splitting is\nproposed. The temporal evolution is calculated analytically, and the convection\nterm is solved via a modifiedWarming-Beam (MWB) scheme.Within theMWB scheme a\nsuitable switch function is introduced. The current model works not only for\nsubsonic flows but also for supersonic flows. It is validated and verified via\nthe following well-known benchmark tests: (i) the rotational flow, (ii) the\nstable shock tube problem, (iii) the Richtmyer-Meshkov (RM) instability, and\n(iv) the Kelvin-Helmholtz instability. As an original application, we studied\nthe nonequilibrium characteristics of the system around three kinds of\ninterfaces, the shock wave, the rarefaction wave, and the material interface,\nfor two specific cases. In one of the two cases, the material interface is\ninitially perturbed, and consequently the RMinstability occurs. It is found\nthat themacroscopic effects due to deviating from thermodynamic equilibrium\naround thematerial interface differ significantly from those around the\nmechanical interfaces. The initial perturbation at the material interface\nenhances the coupling of molecular motions in different degrees of freedom. The\namplitude of deviation from thermodynamic equilibrium around the shock wave is\nmuch higher than those around the rarefaction wave and material interface. By\ncomparing each component of the high-order moments and its value in\nequilibrium, we can draw qualitatively the main behavior of the actual\ndistribution function."
    },
    {
        "anchor": "Phoretic Active Matter: These notes are an account of a series of lectures given at the Les Houches\nSummer School \"Active Matter and Non-equilibrium Statistical Physics\" during\nAugust and September 2018. The lectures can be viewed online at\n[http://www.ds.mpg.de/lmp/lectures/les-houches-2018].",
        "positive": "Effect of aging on the non-linear elasticity and memory formation in\n  materials: Disordered solids often change their elastic response as they slowly age.\nUsing experiments and simulations, we study how aging disordered planar\nnetworks under an applied stress affects their nonlinear elastic response. We\nare able to modify dramatically the elastic properties of our systems in the\nnon-linear regime. Using simulations, we study two models for the microscopic\nevolution of properties of such a material; the first considers changes in the\nmaterial strength while the second considers distortions in the microscopic\ngeometry. Both models capture different aspects of the experiments including\nthe encoding of memories of the aging history of the system and the dramatic\neffects on the material's nonlinear elastic properties. Our results demonstrate\nhow aging can be used to create complex elastic behavior in the nonlinear\nregime."
    },
    {
        "anchor": "Large strain micromechanics of thermoplastic elastomers with random\n  microstructures: Thermoplastic polyurethanes (TPU) are block copolymeric materials composed of\nplastomeric \"hard\" and elastomeric \"soft\" domains, by which they exhibit highly\nresilient yet dissipative large deformation features depending on volume\nfractions and microstructures of the two distinct domains. Here, we develop a\nnew methodology to address the microscopic deformation mechanisms in TPU\nmaterials with highly disordered microstructures. We propose new\nmicromechanical models for randomly dispersed (or occluded) as well as randomly\ncontinuous hard domains, each within a continuous soft structure as widely\nfound in representative TPU materials over a wide range of volume fractions,\nv$_{\\mathrm{hard}}$ = 26.9% to 52.2%. The micromechanical modeling results are\ncompared to experimental data on the macroscopic large strain behaviors\nreported previously (Cho et al. 2017). We explore the role of the dispersed vs.\ncontinuous nature of the geometric features of the random microstructures on\nshape recovery and energy dissipation at the microstructural level in this\nimportant class of phase-separated copolymeric materials.",
        "positive": "Glassy dynamics in granular compaction: Two models are presented to study the influence of slow dynamics on granular\ncompaction. It is found in both cases that high values of packing fraction are\nachieved only by the slow relaxation of cooperative structures. Ongoing work to\nstudy the full implications of these results is discussed."
    },
    {
        "anchor": "Submersed Micropatterned Structures Control Active Nematic Flow,\n  Topology and Concentration: Coupling between flows and material properties imbues rheological matter with\nits wide-ranging applicability, hence the excitement for harnessing the\nrheology of active fluids for which internal structure and continuous energy\ninjection lead to spontaneous flows and complex, out-of-equilibrium dynamics.\nWe propose and demonstrate a convenient, highly tuneable method for controlling\nflow, topology and composition within active films. Our approach establishes\nrheological coupling via the indirect presence of fully submersed\nmicropatterned structures within a thin, underlying oil layer. Simulations\nreveal that micropatterned structures produce effective virtual boundaries\nwithin the superjacent active nematic film due to differences in viscous\ndissipation as a function of depth. This accessible method of applying\nposition-dependent, effective dissipation to the active films presents a\nnon-intrusive pathway for engineering active microfluidic systems.",
        "positive": "Gravity-induced phase phenomena in plate-rod colloidal mixtures: Gravity can affect colloidal suspensions since for micrometer-sized particles\ngravitational and thermal energies can be comparable over vertical length\nscales of a few millimeters. In mixtures, each species possesses a different\nbuoyant mass, which can make experimental results counter-intuitive and\ndifficult to interpret. Here, we revisit from a theoretical perspective iconic\nsedimentation-diffusion-equilibrium experiments on colloidal plate-rod mixtures\nby van der Kooij and Lekkerkerker. We reproduce their findings, including the\nobservation of five different mesophases in a single cuvette. Using\nsedimentation path theory, we incorporate gravity into a microscopic theory for\nthe bulk of a plate-rod mixture. We also show how to disentangle the effects of\ngravity from sedimentation experiments to obtain the bulk behavior and make\npredictions that can be experimentally tested. These include changes in the\nsequence by altering the sample height. We demonstrate that both buoyant mass\nratio and sample height form control parameters to study bulk phase behavior."
    },
    {
        "anchor": "Dislocations, disclinations, and metric anomalies as sources of global\n  strain incompatibility in thin shells: The strain incompatibility equations are discussed for nonlinear\nKirchhoff-Love shells with sources of inhomogeneity arising due to a\ndistribution of topological defects, such as dislocations and disclinations,\nand metric anomalies, such as point defects, thermal strains, and biological\ngrowth. The incompatibility equations are given for all topological surfaces,\nwith or without boundary, which are isometrically embeddable in a 3-dimensional\nEuclidean space.",
        "positive": "Rounded Layering Transitions on the Surface of Ice: Understanding the wetting properties of premelting films requires knowledge\nof the film's equation of state, which is not usually available. Here we\ncalculate the disjoining pressure curve of premelting films, and perform a\ndetailed thermodynamic characterization of premelting behavior on ice. Analysis\nof the density profiles reveals the signature of weak layering phenomena, from\none to two and from two to three water molecular layers. However, disjoining\npressure curves, which closely follow expectations from a renormalized mean\nfield liquid state theory, show that there are no layering phase transitions in\nthe thermodynamic sense along the sublimation line. Instead, we find that\ntransitions at mean field level are rounded due to capillary wave fluctuations.\nWe see signatures that true first order layering transitions could arise at low\ntemperatures, for pressures between the metastable line of water/vapor\ncoexistence and the sublimation line. The extrapolation of the disjoining\npressure curve above water vapor saturation displays a true first order phase\ntransition from a thin to a thick film consistent with experimental\nobservations."
    },
    {
        "anchor": "Pressure Dependence of Fragile-to-Strong Transition and a Possible\n  Second Critical Point in Supercooled Confined Water: By confining water in nano-pores of silica glass, we can bypass the\ncrystallization and study the pressure effect on the dynamical behavior in\ndeeply supercooled state using neutron scattering. We observe a clear evidence\nof a cusp-like fragile-to-strong (F-S) dynamic transition. Here we show that\nthe transition temperature decreases steadily with an increasing pressure,\nuntil it intersects the homogenous nucleation temperature line of bulk water at\na pressure of 1600 bar. Above this pressure, it is no longer possible to\ndiscern the characteristic feature of the F-S transition. Identification of\nthis end point with the possible second critical point is discussed.",
        "positive": "Two-dimensional colloidal fluids exhibiting pattern formation: Fluids with competing short range attraction and long range repulsive\ninteractions between the particles can exhibit a variety of microphase\nseparated structures. We develop a lattice-gas (generalised Ising) model and\nanalyse the phase diagram using Monte Carlo computer simulations and also with\ndensity functional theory (DFT). The DFT predictions for the structures formed\nare in good agreement with the results from the simulations, which occur in the\nportion of the phase diagram where the theory predicts the uniform fluid to be\nlinearly unstable. However, the mean-field DFT does not correctly describe the\ntransitions between the different morphologies, which the simulations show to\nbe analogous to micelle formation. We determine how the heat capacity varies as\nthe model parameters are changed. There are peaks in the heat capacity at state\npoints where the morphology changes occur. We also map the lattice model onto a\ncontinuum DFT that facilitates a simplification of the stability analysis of\nthe uniform fluid."
    },
    {
        "anchor": "Sequence dependence of DNA translocation through a nanopore: We investigate the dynamics of DNA translocation through a nanopore using 2D\nLangevin dynamics simulations, focusing on the dependence of the translocation\ndynamics on the details of DNA sequences. The DNA molecules studied in this\nwork are built from two types of bases $A$ and $C$, which has been shown\npreviously to have different interactions with the pore. We study DNA with\nrepeating blocks $A_nC_n$ for various values of $n$, and find that the\ntranslocation time depends strongly on the {\\em block length} $2n$ as well as\non the {\\em orientation} of which base entering the pore first. Thus, we\ndemonstrate that the measurement of translocation dynamics of DNA through\nnanopore can yield detailed information about its structure. We have also found\nthat the periodicity of the block sequences are contained in the periodicity of\nthe residence time of the individual nucleotides inside the pore.",
        "positive": "Instabilities in a growing system of active particles: scalar and vector\n  systems: The physics of micron-scale biological colonies usually benefits from\ndifferent out-of-equilibrium sources. In bacterial colonies and cellular\ntissues, the growth process is among the important active sources that\ndetermine the dynamics. In this article, we study the generic dynamical\ninstabilities associated with the growth phenomena that may arise in both\nscalar and vectorial systems. In vectorial systems, where the rotational\ndegrees of particles play a role, a phenomenological growthmediated torque can\naffect the rotational dynamics of individual particles. We show that such a\ngrowth-mediated torque can result in active traveling waves in the bulk of a\ngrowing system. In addition to the bulk properties, we analyze the\ninstabilities in the shape of growing interfaces in both scalar and vectorial\nsystems."
    },
    {
        "anchor": "Molecular dynamics simulations of the rotational and translational\n  diffusion of a Janus rod-shaped nanoparticle: The diffusion of a Janus rod-shaped nanoparticle in a dense Lennard-Jones\nfluid is studied using molecular dynamics (MD) simulations. The Janus particle\nis modeled as a rigid cylinder whose atoms on each half-side have different\ninteraction energies with fluid molecules, thus comprising wetting and\nnonwetting surfaces. We found that both rotational and translational diffusion\ncoefficients are larger for Janus particles with higher wettability contrast,\nand these values are bound between the two limiting cases of uniformly wetting\nand nonwetting particles. It was also shown that values of the diffusion\ncoefficients for displacements parallel and perpendicular to the major axis of\na uniformly wetting particle agree well with analytical predictions despite a\nfinite slip at the particle surface present in MD simulations. It was further\ndemonstrated that diffusion of Janus particles is markedly different from that\nof uniform particles; namely, Janus particles preferentially rotate and orient\ntheir nonwetting sides along the displacement vector to reduce drag. This\ncorrelation between translation and rotation is consistent with the previous\nresults on diffusive dynamics of a spherical Janus particle with two\nhemispheres of different wettability.",
        "positive": "Adhesion of membranes via actively switched receptors: We consider a theoretical model for membranes with adhesive receptors, or\nstickers, that are actively switched between two conformational states. In\ntheir 'on'-state, the stickers bind to ligands in an apposing membrane, whereas\nthey do not interact with the ligands in their 'off'-state. We show that the\nadhesiveness of the membranes depends sensitively on the rates of the\nconformational switching process. This dependence is reflected in a resonance\nat intermediate switching rates, which can lead to large membrane separations\nand unbinding. Our results may provide insights into novel mechanisms for the\ncontrolled adhesion of biological or biomimetic membranes."
    },
    {
        "anchor": "Effective field theory approach to Bose--Einstein condensation: We consider the low-energy collective excitations at finite temperature of\nBose--Einstein condensed gases (and liquids as well). A most general\nmodel-independent effective Lagrangian is written down according to a\nprescription obtained from the breakdown of the global symmetry U(1). To show\nhow the theory predicts easily, we derive the momentum and temperature\ndependence of the damping of excitations by means of power counting as an\nexample.",
        "positive": "A new class of plastic flow evolution equations for anisotropic\n  multiplicative elastoplasticity based on the notion of a corrector elastic\n  strain rate: In this paper we present a new general framework for anisotropic\nelastoplasticity at large strains. The new framework presents the following\ncharacteristics: (1) It is valid for non-moderate large strains, (2) it is\nvalid for both elastic and plastic anisotropy, (3) its description in rate form\nis parallel to that of the infinitesimal formulation, (4) it is compatible with\nthe multiplicative decomposition, (5) results in a similar framework in any\nstress-strain work-conjugate pair, (6) it is consistent with the principle of\nmaximum plastic dissipation and (7) does not impose any restriction on the\nplastic spin, which must be given as an independent constitutive equation.\nFurthermore, when formulated in terms of logarithmic strains in the\nintermediate configuration: (8) it may be easily integrated using a classical\nbackward-Euler rule resulting in an additive update. All these properties are\nobtained simply considering a plastic evolution in terms of a corrector rate of\nthe proper elastic strain. This formulation presents a natural framework for\nelastoplasticity of both metals and soft materials and solves the so-called\nrate issue."
    },
    {
        "anchor": "Optical characterization of dyed liquid crystal cells: The guest-host liquid crystal display, first proposed in 1968, relies on\ncontrolling the orientation of dichroic dyes dissolved in a nematic liquid\ncrystal host. Controlling the orientation of the liquid crystal and of the\ndissolved dye with an electric field allows control of the transmittance of the\ncell. Knowing the dielectric properties at optical frequencies of the dye and\nliquid crystal mixtures is crucial for the optimal design of guest-host liquid\ncrystal devices. In this work, the dielectric functions of various layers in\nliquid crystal cells are described by models obeying the Kramers-Kronig\nrelations: the Sellmeier equation for transparent layers and causal Gaussian\noscillator model for absorbing layers. We propose a systematic way to\naccurately model the dielectric response of each layer by minimizing the sum of\nsquared differences between the measured transmittance spectrum of a guest-host\ncell in the near-UV/vis range and the prediction of the transmittance of the\nmodeled multilayer structure. By measuring the transmittance for incident light\npolarized parallel and perpendicular to the nematic director allows us to\nseparately characterize the two principal dielectric functions of the uniaxial\nsample. Our results show that the causal Gaussian oscillator model can\naccurately characterize the dielectric functions of dyes in liquid crystals.",
        "positive": "Anisotropic odd viscosity via time-modulated drive: At equilibrium, the structure and response of ordered phases are typically\ndetermined by the spontaneous breaking of spatial symmetries. Out of\nequilibrium, spatial order itself can become a dynamically emergent concept. In\nthis article, we show that spatially anisotropic viscous coefficients and\nstresses can be designed in a far-from-equilibrium fluid by applying to its\nconstituents a time-modulated drive. If the drive induces a rotation whose rate\nis slowed down when the constituents point along specific directions,\nanisotropic structures and mechanical responses arise at long timescales. We\ndemonstrate that the viscous response of such anisotropic driven fluids can\nacquire a tensorial, dissipationless component called anisotropic odd (or Hall)\nviscosity. Classical fluids with internal torques can display additional\ncomponents of the odd viscosity neglected in previous studies of quantum Hall\nfluids that assumed angular momentum conservation. We show that these\nanisotropic and angular momentum-violating odd-viscosity coefficients can\nchange even the bulk flow of an incompressible fluid by acting as a source of\nvorticity. In addition, shear distortions in the shape of an inclusion result\nin torques."
    },
    {
        "anchor": "Chain conformation of ring polymers under a cylindrical nanochannel\n  confinement: We investigate the chain conformation of ring polymers confined to a\ncylindrical nanochannel using both theoretical analysis and three dimensional\nLangevin dynamics simulations. We predict that the longitudinal size of a ring\npolymer scales with the chain length and the diameter of the channel in the\nsame manner as that for linear chains based on scaling analysis and Flory-type\ntheory. Moreover, Flory-type theory also gives the ratio of the longitudinal\nsizes for a ring polymer and a linear chain with identical chain length. These\ntheoretical predictions are confirmed by numerical simulations. Finally, our\nsimulation results show that this ratio first decreases and then saturates with\nincreasing the chain stiffness, which has interpreted the discrepancy in\nexperiments. Our results have biological significance.",
        "positive": "Square root singularity in the viscosity of neutral colloidal\n  suspensions at large frequencies: The asymptotic frequency $\\omega$, dependence of the dynamic viscosity of\nneutral hard sphere colloidal suspensions is shown to be of the form $\\eta_0\nA(\\phi) (\\omega \\tau_P)^{-1/2}$, where $A(\\phi)$ has been determined as a\nfunction of the volume fraction $\\phi$, for all concentrations in the fluid\nrange, $\\eta_0$ is the solvent viscosity and $\\tau_P$ the P\\'{e}clet time. For\na soft potential it is shown that, to leading order steepness, the asymptotic\nbehavior is the same as that for the hard sphere potential and a condition for\nthe cross-over behavior to $1/\\omega \\tau_P$ is given. Our result for the hard\nsphere potential generalizes a result of Cichocki and Felderhof obtained at low\nconcentrations and agrees well with the experiments of van der Werff et al, if\nthe usual Stokes-Einstein diffusion coefficient $D_0$ in the Smoluchowski\noperator is consistently replaced by the short-time self diffusion coefficient\n$D_s(\\phi)$ for non-dilute colloidal suspensions."
    },
    {
        "anchor": "Effects of passive phospholipid flip-flop and asymmetric external fields\n  on bilayer phase equilibria: Compositional asymmetry between the leaflets of bilayer membranes modifies\ntheir phase behaviour, and is thought to influence other important features\nsuch as mechanical properties and protein activity. We address here how phase\nbehaviour is affected by passive phospholipid \\textit{flip-flop}, such that the\ncompositional asymmetry is not fixed. We predict transitions from \"pre\nflip-flop\" behaviour to a restricted set of phase equilibria that can persist\nin the presence of passive flip-flop. Surprisingly, such states are not\nnecessarily symmetric. We further account for external symmetry-breaking, such\nas a preferential substrate interaction, and show how this can stabilise\nstrongly asymmetric equilibrium states. Our theory explains several\nexperimental observations of flip-flop mediated changes in phase behaviour, and\nshows how domain formation and compositional asymmetry can be controlled in\nconcert, by manipulating passive flip-flop rates and applying external fields.",
        "positive": "Bistable curvature potential at hyperbolic points of nematic shells: Nematic shells are colloidal particles coated with nematic liquid crystal\nmolecules which may freely glide and rotate on the colloid's surface while\nkeeping their long axis on the local tangent plane. We describe the nematic\norder on a shell by a unit director field on an orientable surface. Equilibrium\nfields can then be found by minimising the elastic energy, which in general is\na function of the surface gradient of the director field. We learn how to\nextract systematically out of this energy a fossil component, related only to\nthe surface and its curvatures, which expresses a curvature potential for the\nmolecular torque. At hyperbolic points on the colloid's surface, and only\nthere, the alignment preferred by the curvature potential may fail to be a\ndirection of principal curvature. There the fossil energy becomes bistable."
    },
    {
        "anchor": "Visualizing the strain field in semiflexible polymer networks: strain\n  fluctuations and nonlinear rheology of F-actin gels: We image semi-flexible polymer networks under shear at the micrometer scale.\nBy tracking embedded probe particles, we determine the local strain field, and\ndirectly measure its uniformity, or degree of affineness, on scales of 2-100\nmicron. The degree of nonaffine strain depends on polymer length and crosslink\ndensity, consistent with theoretical predictions. We also find a direct\ncorrespondence between the uniformity of the microscale strain and the\nnonlinear elasticity of the networks in the bulk.",
        "positive": "Strain softening and stiffening responses of spider silk fibers probed\n  using Micro-Extension Rheometer: Spider silk possesses unique mechanical properties like large extensibility,\nhigh tensile strength, super-contractility, etc. Understanding these mechanical\nresponses require characterization of the rheological properties of silk beyond\nthe simple force-extension relations which are widely reported. Here we study\nthe linear and non-linear viscoelastic properties of dragline silk obtained\nfrom social spiders Stegodyphus sarasinorum using a Micro-Extension Rheometer\nthat we have developed. Unlike continuous extension data, our technique allows\nfor the probing of the viscoelastic response by applying small perturbations\nabout sequentially increasing steady-state strain values. In addition, we\nextend our analysis to obtain the characteristic stress relaxation times and\nthe frequency responses of the viscous and elastic moduli. Using these methods,\nwe show that in a small strain regime (0-4%) dragline silk of social spiders\nshows strain-softening response followed by strain-stiffening response at\nhigher strains (> 4%). The stress relaxation time, on the other hand, increases\nmonotonically with increasing strain for the entire range. We also show that\nsilk stiffens while ageing within the typical lifetime of a web. Our results\ndemand the inclusion of the kinetics of domain unfolding and refolding in the\nexisting models to account for the relaxation time behaviour."
    },
    {
        "anchor": "Non-extensivity of the chemical potential of polymer melts: Following Flory's ideality hypothesis the chemical potential of a test chain\nof length $n$ immersed into a dense solution of chemically identical polymers\nof length distribution P(N) is extensive in $n$. We argue that an additional\ncontribution $\\delta \\mu_c(n) \\sim +1/\\rho\\sqrt{n}$ arises ($\\rho$ being the\nmonomer density) for all $\\P(N)$ if $n \\ll <N>$ which can be traced back to the\noverall incompressibility of the solution leading to a long-range repulsion\nbetween monomers. Focusing on Flory distributed melts we obtain $\\delta\n\\mu_c(n) \\approx (1- 2 n/<N>) / \\rho \\sqrt{n}$ for $n \\ll <N>^2$, hence,\n$\\delta \\mu_c(n) \\approx - 1/\\rho \\sqrt{n}$ if $n$ is similar to the typical\nlength of the bath $<N>$. Similar results are obtained for monodisperse\nsolutions. Our perturbation calculations are checked numerically by analyzing\nthe annealed length distribution P(N) of linear equilibrium polymers generated\nby Monte Carlo simulation of the bond-fluctuation model. As predicted we find,\ne.g., the non-exponentiality parameter $K_p \\equiv 1 - <N^>/p!<N>^p$ to decay\nas $K_p \\approx 1 / \\sqrt{<N>}$ for all moments $p$ of the distribution.",
        "positive": "A pulsed atomic soliton laser: It is shown that simultaneously changing the scattering length of an\nelongated, harmonically trapped Bose-Einstein condensate from positive to\nnegative and inverting the axial portion of the trap, so that it becomes\nexpulsive, results in a train of self-coherent solitonic pulses. Each pulse is\nitself a non-dispersive attractive Bose-Einstein condensate that rapidly\nself-cools. The axial trap functions as a waveguide. The solitons can be made\nrobustly stable with the right choice of trap geometry, number of atoms, and\ninteraction strength. Theoretical and numerical evidence suggests that such a\npulsed atomic soliton laser can be made in present experiments."
    },
    {
        "anchor": "Network of Hydrogen Bonds as a Medium for DNA Interaction in Solvents: We suggest that the DNA molecules could form the cholesteric phase owing to\nan interaction mediated by the network of the hydrogen bonds (H-network) in the\nsolvent. The model admits of the dependence of the optical activity of the\nsolution on the concentration of the PEG, and the change in the sense of the\ncholesteric twist due to the intercalation by the daunomicyn. Using the\nexperimental data for the cholesteric phase of the DNA dispersion, we obtain a\nrough estimate for the energy given by our model, and show that it should be\ntaken into account as well as the energy due to the steric repulsion, van der\nWaals, and electrostatic forces, generally used for studying the DNA molecules.\nThe elastic constant of the H-network generating the interaction between the\nDNA molecules is determined by the energy due to the proton's vibration in the\nhydrogen bonds.",
        "positive": "Rheology of giant micelles: Giant micelles are elongated, polymer-like objects created by the\nself-assembly of amphiphilic molecules (such as detergents) in solution. Giant\nmicelles are typically flexible, and can become highly entangled even at modest\nconcentrations. The resulting viscoelastic solutions show fascinating flow\nbehaviour (rheology) which we address theoretically in this article at two\nlevels. First, we summarise advances in understanding linear viscoelastic\nspectra and steady-state nonlinear flows, based on microscopic constitutive\nmodels that combine the physics of polymer entanglement with the reversible\nkinetics of self-assembly. Such models were first introduced two decades ago,\nand since then have been shown to explain robustly several distinctive features\nof the rheology in the strongly entangled regime, including extreme\nshear-thinning. We then turn to more complex rheological phenomena,\nparticularly involving spatial heterogeneity, spontaneous oscillation,\ninstability, and chaos. Recent understanding of these complex flows is based\nlargely on grossly simplified models which capture in outline just a few\npertinent microscopic features, such as coupling between stresses and other\norder parameters such as concentration. The role of `structural memory' (the\ndependence of structural parameters such as the micellar length distribution on\nthe flow history) in explaining these highly nonlinear phenomena is addressed.\nStructural memory also plays an intriguing role in the little-understood\nshear-thickening regime, which occurs in a concentration regime close to but\nbelow the onset of strong entanglement, and which is marked by a shear-induced\ntransformation from an inviscid to a gelatinous state."
    },
    {
        "anchor": "Phonon Spectra, Nearest Neighbors, and Mechanical Stability of\n  Disordered Colloidal Clusters with Attractive Interactions: We investigate the influence of morphology and size on the vibrational\nproperties of disordered clusters of colloidal particles with attractive\ninteractions. From measurements of displacement correlations between particles\nin each cluster, we extract vibrational properties of the corresponding\n\"shadow\" glassy cluster, with the same geometric configuration and interactions\nas the \"source\" cluster but without damping. Spectral features of the\nvibrational modes are found to depend strongly on the average number of nearest\nneighbors, $\\bar{NN}$, but only weakly on the number of particles in each\nglassy cluster. In particular, the median phonon frequency, $\\omega_{med}$, is\nessentially constant for $\\bar{NN}$ $<2$ and then grows linearly with\n$\\bar{NN}$ for $\\bar{NN}$ $>2$. This behavior parallels concurrent observations\nabout local isostatic structures, which are absent in clusters with $\\bar{NN}$\n$<2$ and then grow linearly in number for $\\bar{NN}$$>2$. Thus, cluster\nvibrational properties appear to be strongly connected to cluster mechanical\nstability (i.e., fraction of locally isostatic regions), and the scaling of\n$\\omega_{med}$ with $\\bar{NN}$ is reminiscent of the behavior of packings of\nspheres with repulsive interactions at the jamming transition. Simulations of\nrandom networks of springs corroborate observations and suggest that\nconnections between phonon spectra and nearest neighbor number are generic to\ndisordered networks.",
        "positive": "Shear-induced phase transition and critical exponents in 3D fiber\n  networks: When subject to applied strain, fiber networks exhibit nonlinear elastic\nstiffening. Recent theory and experiements have shown that this phenomenon is\ncontrolled by an underlying mechanical phase transition that is critical in\nnature. Growing simulation evidence points to non-mean-field behavior for this\ntransition and a hyperscaling relation has been proposed to relate the\ncorresponding critical exponents. Here, we report simulations on two distinct\nnetwork structures in 3D. By performing finite-size scaling analysis, we test\nhyperscaling and identify various critical exponents. From the apparent\nvalidity of hyperscaling, as well as the non-mean-field exponents we observe,\nour results suggest that the upper critical dimension for the strain-controlled\nphase transition is above three, in contrast to the jamming transition that\nrepresents another athermal, mechanical phase transition."
    },
    {
        "anchor": "Membrane adhesion and domain formation: We review theoretical results for the adhesion-induced phase behavior of\nbiomembranes. The focus is on models in which the membranes are represented as\ndiscretized elastic sheets with embedded adhesion molecules. We present several\nmechanism that lead to the formation of domains during adhesion, and discuss\nthe time-dependent evolution of domain patterns obtained in Monte-Carlo\nsimulations. The simulated pattern dynamics has striking similarities to the\npattern evolution observed during T cell adhesion.",
        "positive": "Guiding microscale swimmers using teardrop-shaped posts: The swimming direction of biological or artificial microscale swimmers tends\nto be randomised over long time-scales by thermal fluctuations. Bacteria use\nvarious strategies to bias swimming behaviour and achieve directed motion\nagainst a flow, maintain alignment with gravity or travel up a chemical\ngradient. Herein, we explore a purely geometric means of biasing the motion of\nartificial nanorod swimmers. These artificial swimmers are bimetallic rods,\npowered by a chemical fuel, which swim on a substrate printed with\nteardrop-shaped posts. The artificial swimmers are hydrodynamically attracted\nto the posts, swimming alongside the post perimeter for long times before\nleaving. The rods experience a higher rate of departure from the higher\ncurvature end of the teardrop shape, thereby introducing a bias into their\nmotion. This bias increases with swimming speed and can be translated into a\nmacroscopic directional motion over long times by using arrays of\nteardrop-shaped posts aligned along a single direction. This method provides a\nprotocol for concentrating swimmers, sorting swimmers according to different\nspeeds, and could enable artificial swimmers to transport cargo to desired\nlocations."
    },
    {
        "anchor": "Universal velocity distributions in an experimental granular fluid: We present experimental results on the velocity statistics of a uniformly\nheated granular fluid, in a quasi-2D configuration. We find the base state, as\nmeasured by the single particle velocity distribution $f(c)$, to be universal\nover a wide range of filling fractions and only weakly dependent on all other\nsystem parameters. There is a consistent overpopulation in the distribution's\ntails, which scale as $f\\propto\\exp(\\mathrm{const.}\\times c^{-3/2})$. More\nimportantly, the high probability central region of $f(c)$, at low velocities,\ndeviates from a Maxwell-Boltzmann by a second order Sonine polynomial with a\nsingle adjustable parameter, in agreement with recent theoretical analysis of\ninelastic hard spheres driven by a stochastic thermostat. To our knowledge,\nthis is the first time that Sonine deviations have been measured in an\nexperimental system.",
        "positive": "Topological defects reveal the plasticity of glasses: Mixing theoretical topological structures with cutting-edge simulation\nmethods, a recent study in Nature Communications has finally confirmed the\nexistence of topological defects in glasses and their crucial role for\nplasticity."
    },
    {
        "anchor": "WHAT IS LIFE - Sub-cellular Physics of Live Matter: This is a set of lectures that I presented at the Les Houches 2014 Summer\nSchool \"Topological Aspects in Condensed Matter Physics\". The lectures are an\nintroduction to physics of proteins. To physicists, and by a physicist. My\nlectures at les Houches were also celebration of the anniversary of\nSchroedinger's 1944 lectures, and for that reason I decided to share my title\nwith his book.",
        "positive": "Structural transition of force chains observed by mechanical\n  spectroscopy: The dissipation properties of a fine sand system are investigated by a\nlow-frequency mechanical spectroscopy. The experiments show many interesting\nprofiles of the relative energy dissipation, which imply that some structural\ntransition of force chains in dense granular media has occurred. The following\ndata and discussion indicate that the transition of force chains will lead to\nthe small deformation of arrangement in the granular system, which is\nresponsible for the historical effects. We hope this research can improve our\nknowledge of the microstructure of the granular materials."
    },
    {
        "anchor": "Cell-sized confinements alter molecular diffusion in concentrated\n  polymer solutions due to length-dependent wetting of polymers: Living cells are characterized by the micrometric confinement of various\nmacromolecules at high concentrations. Using droplets containing binary polymer\nblends as artificial cells, we previously showed that cell-sized confinement\ncauses phase separation of the binary polymer solutions because of the\nlength-dependent wetting of the polymers. Here we demonstrate that the\nwetting-induced heterogeneity of polymers also emerges in single-component\npolymer solutions. The resulting heterogeneity leads to a slower transport of\nsmall molecules at the center of cell-sized droplets than that in bulk\nsolutions. This heterogeneous distribution is observed when longer polymers\nwith lower wettability are localized at the droplet center. Molecular\nsimulations support this wetting-induced heterogeneous distribution by polymer\nlength. Our results suggest that cell-sized confinement functions as a\nstructural regulator for polydisperse polymer solutions that specifically\nmanipulate the diffusion of molecules, particularly those with sizes close to\nthe correlation length of the polymer chains.",
        "positive": "Paranematic-to-nematic ordering of a binary mixture of rod-like liquid\n  crystals confined in cylindrical nanochannels: We explore the optical birefringence of the nematic binary mixtures\n6CB$_{1-x}$7CB$_x$ ($0~\\le~x~\\le~1$) imbibed into parallel-aligned nanochannels\nof mesoporous alumina and silica membranes for channel radii of $3.4~\\le~R~\\le\n21.0$ nm. The results are compared with the bulk behavior and analyzed with a\nLandau-de-Gennes model. Depending on the channel radius the nematic ordering in\nthe cylindrical nanochannels evolves either discontinuously (subcritical\nregime, nematic ordering field $\\sigma<1/2$) or continuously (overcritical\nregime, $\\sigma>1/2$), but in both cases with a characteristic paranematic\nprecursor behavior. The strength of the ordering field, imposed by the channel\nwalls, and the magnitude of quenched disorder varies linearly with the mole\nfraction $x$ and scales inversely proportionally with $R$ for channel radii\nlarger than 4 nm. The critical pore radius, $R_c$, separating a continuous from\na discontinuous paranematic-to-nematic evolution, varies linearly with $x$ and\ndiffers negligibly between the silica and alumina membranes. We find no hints\nof preferred adsorption of one species at the channels walls. By contrast, a\nlinear variation of the nematic-to-paranematic transition point $T_{\\rm PN}$\nand of the nematic ordering field $\\sigma$ vs. $x$ suggest that the binary\nmixtures of cyanobiphenyls 6CB and 7CB keep their homogeneous bulk\nstoichiometry also in nanoconfinement, at least for channel diameters larger\nthan $\\sim$7 nm."
    },
    {
        "anchor": "Irreversible reorganization in a supercooled liquid originates from\n  localised soft modes: The transition of a fluid to a rigid glass upon cooling is a common route of\ntransformation from liquid to solid that embodies the most poorly understood\nfeatures of both phases1,2,3. From the liquid perspective, the puzzle is to\nunderstand stress relaxation in the disordered state. From the perspective of\nsolids, the challenge is to extend our description of structure and its\nmechanical consequences to materials without long range order. Using computer\nsimulations, we show that the localized low frequency normal modes of a\nconfiguration in a supercooled liquid are causally correlated to the\nirreversible structural reorganization of the particles within that\nconfiguration. We also demonstrate that the spatial distribution of these soft\nlocal modes can persist in spite of significant particle reorganization. The\nconsequence of these two results is that it is now feasible to construct a\ntheory of relaxation length scales in glass-forming liquids without recourse to\ndynamics and to explicitly relate molecular properties to their collective\nrelaxation.",
        "positive": "Classification of complex local environments in systems of particle\n  shapes through shape-symmetry encoded data augmentation: Detecting and analyzing the local environment is crucial for investigating\nthe dynamical processes of crystal nucleation and shape colloidal particle\nself-assembly. Recent developments in machine learning provide a promising\navenue for better order parameters in complex systems that are challenging to\nstudy using traditional approaches. However, the application of machine\nlearning to self-assembly on systems of particle shapes is still underexplored.\nTo address this gap, we propose a simple, physics-agnostic, yet powerful\napproach that involves training a multilayer perceptron (MLP) as a local\nenvironment classifier for systems of particle shapes, using input features\nsuch as particle distances and orientations. Our MLP classifier is trained in a\nsupervised manner with a shape symmetry-encoded data augmentation technique\nwithout the need for any conventional roto-translations invariant symmetry\nfunctions. We evaluate the performance of our classifiers on four different\nscenarios involving self-assembly of cubic structures, 2-dimensional and\n3-dimensional patchy particle shape systems, hexagonal bipyramids with varying\naspect ratios, and truncated shapes with different degrees of truncation. The\nproposed training process and data augmentation technique are both\nstraightforward and flexible, enabling easy application of the classifier to\nother processes involving particle orientations. Our work thus presents a\nvaluable tool for investigating self-assembly processes on systems of particle\nshapes, with potential applications in structure identification of any\nparticle-based or molecular system where orientations can be defined."
    },
    {
        "anchor": "Viscous fingering in the presence of weak disorder: We consider the problem of viscous fingering in the presence of quenched\ndisorder that is both weak and short-range correlated. The two point\ncorrelation function of the harmonic measure is calculated perturbatively, and\nis used in order to calculate the correction the the box-counting fractal\ndimension. We show that the disorder increases the fractal dimension, and that\nits effect decreases logarithmically with the size of the fractal.",
        "positive": "An inventory of Lattice Boltzmann models of multiphase flows: This document reports investigations of models of multiphase flows using\nLattice Boltzmann methods. The emphasis is on deriving by Chapman-Enskog\ntechniques the corresponding macroscopic equations. The singular interface\n(Young-Laplace-Gauss) model is described briefly, with a discussion of its\nlimitations. The diffuse interface theory is discussed in more detail, and\nshown to lead to the singular interface model in the proper asymptotic limit.\nThe Lattice Boltzmann method is presented in its simplest form appropriate for\nan ideal gas. Four different Lattice Boltzmann models for non-ideal\n(multi-phase) isothermal flows are then presented in detail, and the resulting\nmacroscopic equations derived. Partly in contradiction with the published\nliterature, it is found that only one of the models gives physically fully\nacceptable equations. The form of the equation of state for a multiphase system\nin the density interval above the coexistance line determines surface tension\nand interface thickness in the diffuse interface theory. The use of this\nrelation for optimizing a numerical model is discussed. The extension of\nLattice Boltzmann methods to the non-isothermal situation is discussed\nsummarily."
    },
    {
        "anchor": "Phase Behavior and Selectivity of DNA-linked Nanoparticle Assemblies: We propose a model that can account for the experimentally observed phase\nbehavior of DNA-nanoparticle assemblies (R. Jin et al., JACS 125, 1643 (2003);\nT. A. Taton et al., Science 289, 1757 (2000)). The binding of DNA-coated\nnano-particles by dissolved DNA linker can be described by exploiting an\nanalogy with quantum particles obeying fractional statistics. In accordance\nwith experimental findings, we predict that the phase-separation temperature of\nthe nano-colloids increases with the DNA coverage of the colloidal surface.\nUpon the addition of salt, the demixing temperature increases logarithmically\nwith the salt concentration. Our analysis suggests an experimental strategy to\nmap microscopic DNA sequences onto the macroscopic phase behavior of the\nDNA-nanoparticle solutions. Such an approach should enhance the efficiency of\nmethods to detect (single) mutations in specific DNA sequences.",
        "positive": "Sequence Effects on Internal Structure of Droplets of Associative\n  Polymers: We used Langevin dynamics simulations of short associative polymers with two\nstickers placed symmetrically along their contour to study the effect of the\nprimary sequence of these polymers on their organization inside condensed\ndroplets. We observed that the shape, size and number of sticker clusters\ninside the condensed droplet change from a single cylindrical fiber to many\ncompact clusters, as one varies the location of stickers along the chain\ncontour. Aging due to conversion of intramoleclular to intermolecular\nassociations was observed in droplets of telechelic polymers, but not for other\nsequences of associating polymers. The relevance of our results to condensates\nof intrinsically disordered proteins is discussed."
    },
    {
        "anchor": "Molecular-Brownian Correspondence in the Hard-sphere Dynamic\n  Universality Class: We perform systematic simulation experiments on model systems with\nsoft-sphere repulsive interactions to test the predicted dynamic equivalence\nbetween soft-sphere liquids with similar static structure. For this we compare\nthe simulated dynamics (mean squared displacement, intermediate scattering\nfunction, {\\alpha}-relaxation time, etc.) of different soft-sphere systems,\nbetween them and with the hard-sphere liquid. We then show that the referred\ndynamic equivalence does not depend on the (Newtonian or Brownian) nature of\nthe microscopic laws of motion of the constituent particles, and hence, applies\nindependently to colloidal and to atomic simple liquids. In addition, we verify\nanother more recently-proposed dynamic equivalence, this time between the\nlong-time dynamics of a Brownian fluid and its corresponding atomic liquid\n(i.e., the atomic system with the same interaction potential).",
        "positive": "Ordering leads to multiple fast tracks in simulated collective escape of\n  human crowds: Elucidating emergent regularities in intriguing crowd dynamics is a\nfundamental scientific problem arising in multiple fields. In this work, based\non the social force model, we simulate the typical scenario of collective\nescape towards a single exit and reveal the striking analogy of crowd dynamics\nand crystallisation. With the outflow of the pedestrians, crystalline order\nemerges in the compact crowd. In this process, the local misalignment and\nglobal rearrangement of pedestrians are well rationalized in terms of the\ncharacteristic motions of topological defects in the crystal. Exploiting the\nnotions from the physics of crystallisation further reveals the emergence of\nmultiple fast tracks in the collective escape."
    },
    {
        "anchor": "Dynamics of a trapped 2D Bose-Einstein condensate with periodically and\n  randomly varying atomic scattering length: In this work we consider the oscillations and associated resonance of a 2D\nBose-Einstein condensate under periodic and random modulations of the atomic\nscattering length. For random oscillations of the trap potential and of the\natomic scattering length we are able to calculate the mean growth rate for the\nwidth of the condensate. The results obtained from the reduced ODE's for\noscillations of the width of condensate are compared with the numerical\nsimulations of the full 2D Gross-Pitaevskii equation with modulated in time\ncoefficients.",
        "positive": "Theoretical Study of Comb-Polymers Adsorption on Solid Surfaces: We propose a theoretical investigation of the physical adsorption of neutral\ncomb-polymers with an adsorbing skeleton and non-adsorbing side-chains on a\nflat surface. Such polymers are particularly interesting as \"dynamic coating\"\nmatrices for bio-separations, especially for DNA sequencing, capillary\nelectrophoresis and lab-on-chips. Separation performances are increased by\ncoating the inner surface of the capillaries with neutral polymers. This method\nallows to screen the surface charges, thus to prevent electro-osmosis flow and\nadhesion of charged macromolecules (e.g. proteins) on the capillary walls. We\nidentify three adsorption regimes: a \"mushroom\" regime, in which the coating is\nformed by strongly adsorbed skeleton loops and the side-chains anchored on the\nskeleton are in a swollen state, a \"brush\" regime, characterized by a uniform\nmulti-chains coating with an extended layer of non-adsorbing side-chains and a\nnon-adsorbed regime. By using a combination of mean field and scaling\napproaches, we explicitly derive asymptotic forms for the monomer concentration\nprofiles, for the adsorption free energy and for the thickness of the adsorbed\nlayer as a function of the skeleton and side-chains sizes and of the adsorption\nparameters. Moreover, we obtain the scaling laws for the transitions between\nthe different regimes. These predictions can be checked by performing\nexperiments aimed at investigating polymer adsorption, such as Neutron or X-ray\nReflectometry, Ellipsometry, Quartz Microbalance, or Surface Force Apparatus."
    },
    {
        "anchor": "Density functional theory for the crystallization of two-dimensional\n  dipolar colloidal alloys: Two-dimensional mixtures of dipolar colloidal particles with different dipole\nmoments exhibit extremely rich self-assembly behaviour and are relevant to a\nwide range of experimental systems, including charged and super-paramagnetic\ncolloids at liquid interfaces. However, there is a gap in our understanding of\nthe crystallization of these systems because existing theories such as integral\nequation theory and lattice sum methods can only be used to study the high\ntemperature fluid phase and the zero-temperature crystal phase, respectively.\nIn this paper we bridge this gap by developing a density functional theory\n(DFT), valid at intermediate temperatures, in order to study the\ncrystallization of one and two-component dipolar colloidal monolayers. The\ntheory employs a series expansion of the excess Helmholtz free energy\nfunctional, truncated at second order in the density, and taking as input\nhighly accurate bulk fluid direct correlation functions from simulation.\nAlthough truncating the free energy at second order means that we cannot\ndetermine the freezing point accurately, our approach allows us to calculate ab\ninitio both the density profiles of the different species and the symmetry of\nthe final crystal structures. Our DFT predicts hexagonal crystal structures for\none-component systems, and a variety of superlattice structures for\ntwo-component systems, including those with hexagonal and square symmetry, in\nexcellent agreement with known results for these systems. The theory also\nprovides new insights into the structure of two-component systems in the\nintermediate temperature regime where the small particles remain molten but the\nlarge particles are frozen on a regular lattice.",
        "positive": "Signatures of Topological Phonons in Superisostatic Lattices: Soft topological surface phonons in idealized ball-and-spring lattices with\ncoordination number $z=2d$ in $d$ dimensions become finite-frequency surface\nphonons in physically realizable superisostatic lattices with $z>2d$. We study\nthese finite-frequency modes in model lattices with added next-nearest-neighbor\nsprings or bending forces at nodes with an eye to signatures of the topological\nsurface modes that are retained in the physical lattices. Our results apply to\nmetamaterial lattices, prepared with modern printing techniques, that closely\napproach isostaticity."
    },
    {
        "anchor": "Uncertainty quantification and estimation in differential dynamic\n  microscopy: Differential dynamic microscopy (DDM) is a form of video image analysis that\ncombines the sensitivity of scattering and the direct visualization benefits of\nmicroscopy. DDM is broadly useful in determining dynamical properties including\nthe intermediate scattering function for many spatiotemporally correlated\nsystems. Despite its straightforward analysis, DDM has not been fully adopted\nas a routine characterization tool, largely due to computational cost and lack\nof algorithmic robustness. We present statistical analysis that quantifies the\nnoise, reduces the computational order and enhances the robustness of DDM\nanalysis. We propagate the image noise through the Fourier analysis, which\nallows us to comprehensively study the bias in different estimators of model\nparameters, and we derive a different way to detect whether the bias is\nnegligible. Furthermore, through use of Gaussian process regression (GPR), we\nfind that predictive samples of the image structure function require only\naround 0.5%-5% of the Fourier transforms of the observed quantities. This\nvastly reduces computational cost, while preserving information of the\nquantities of interest, such as quantiles of the image scattering function, for\nsubsequent analysis. The approach, which we call DDM with uncertainty\nquantification (DDM-UQ), is validated using both simulations and experiments\nwith respect to accuracy and computational efficiency, as compared with\nconventional DDM and multiple particle tracking. Overall, we propose that\nDDM-UQ lays the foundation for important new applications of DDM, as well as to\nhigh-throughput characterization. We implement the fast computation tool in a\nnew, publicly available MATLAB software package.",
        "positive": "Structural anisotropy of silica hydrogels prepared under magnetic field: Birefringence measurements have been carried out on the Pb-doped silica\nhydrogels prepared under various magnetic fields up to 5T. The silica gels\nprepared at 5T were used as a medium of crystal growth of PbBr2, whose result\nimplied the structural anisotropy; an aligned array of crystallites was\nobtained by transmission electron microscopy. While the samples prepared at 0,\n1, and 3T have no birefringence, we found that the samples have negative\nbirefringence on the order of magnitude 10^-6 as if the direction of the\nmagnetic field is the optic axis of a uniaxal crystal. To the authors'\nknowledge, the birefringent silica hydrogels were obtained by gelation under\nmagnetic field for the first time. Also, scanning microscopic light scattering\nexperiments have been performed. The results indicate that the characteristic\nlength distribution for birefringent samples is narrower than that for\nnon-birefringent ones."
    },
    {
        "anchor": "Gas Diffusion in Cement Pastes: An Analysis using a Fluctuating\n  Diffusivity Model: This work propose an application of the concept of fluctuating diffusivity to\nthe diffusion of gas molecules in cementitious materials, particularly through\na two-state fluctuating diffusivity (2SFD) model. The 2SFD model is utilized to\ninvestigate the diffusion of oxygen in cement pastes. The analysis provides a\nreasonable description of the diffusion coefficient of oxygen in cement pastes,\nand highlights the presence of non-Gaussian diffusion, which can be attributed\nto the heterogeneous microstructure. The presence of non-Gaussianity in the\nprobability density of the molecule's displacement, characterized by heavier\ntails than those of the Gaussian distribution, may have a significant impact on\nthe durability assessments of concrete structures.",
        "positive": "Nonlinear viscoelasticity and generalized failure criterion for polymer\n  gels: Polymer gels behave as soft viscoelastic solids and exhibit a generic\nnonlinear mechanical response characterized by pronounced stiffening prior to\nirreversible failure, most often through macroscopic fractures. Here, we aim at\ncapturing the latter scenario for a protein gel using a nonlinear integral\nconstitutive equation built upon ($i$) the linear viscoelastic response of the\ngel, here well described by a power-law relaxation modulus, and ($ii$) the\nnonlinear viscoelastic properties of the gel, encoded into a \"damping\nfunction\". Such formalism predicts quantitatively the gel mechanical response\nto a shear start-up experiment, up to the onset of macroscopic failure.\nMoreover, as the gel failure involves the irreversible growth of macroscopic\ncracks, we couple the latter stress response with Bailey's durability criterion\nfor brittle solids in order to predict the critical values of the stress\n$\\sigma_c$ and strain $\\gamma_c$ at the failure point, and how they scale with\nthe applied shear rate. The excellent agreement between theory and experiments\nsuggests that the crack growth in this soft viscoelastic gel is a Markovian\nprocess, and that Baileys' criterion extends well beyond hard materials such as\nmetals, glasses, or minerals."
    },
    {
        "anchor": "Simple views on symmetries and dualities in the theory of elasticity: Microscopic symmetries impose strong constraints on the elasticity of a\ncrystalline solid. In addition to the usual spatial symmetries captured by the\ntensorial character of the elastic tensor, hidden non-spatial symmetries can\noccur microscopically in special classes of mechanical structures. Examples of\nsuch non-spatial symmetries occur in families of mechanical metamaterials where\na duality transformation relates pairs of different configurations. We show on\ngeneral grounds how the existence of non-spatial symmetries further constrains\nthe elastic tensor, reducing the number of independent moduli. In systems\nexhibiting a duality transformation, the resulting constraints on the number of\nmoduli are particularly stringent at the self-dual point but persist even away\nfrom it, in a way reminiscent of critical phenomena.",
        "positive": "Physical aging studied by a device allowing for rapid thermal\n  equilibration: Aging to the equilibrium liquid state of organic glasses is studied. The\nglasses were prepared by cooling the liquid to temperatures just below the\nglass transition. Aging following a temperature jump was studied by measuring\nthe dielectric loss at a fixed frequency using a microregulator in which\ntemperature is controlled by means of a Peltier element. Compared to\nconventional equipment the new device adds almost two orders of magnitude to\nthe span of observable aging times. Data for the following five glass-forming\nliquids are presented: Dibutyl phthalate, diethyl phthalate, 2,3-epoxy\npropyl-phenyl-ether, 5-polyphenyl-ether, and triphenyl phosphite. The aging\ndata were analyzed using the Tool-Narayanaswamy formalism. The following\nfeatures are found for all five liquids: 1) Each liquid has an \"internal\nclock\", a fact that is established by showing that the aging of the structure\nis controlled by the same material time that controls the dielectric\nproperties. 2) There are no so-called expansion gaps between the long-time\nlimits of the relaxation rates following up and down jumps to the same\ntemperature. 3) At long times the structural relaxation is not stretched, but a\nsimple exponential decay. 4) For small temperature steps the rate of the\nlong-time exponential structural relaxation is identical to that of the\nlong-time decay of the dipole autocorrelation function."
    },
    {
        "anchor": "Delocalizing transition of multidimensional solitons in Bose-Einstein\n  condensates: Critical behavior of solitonic waveforms of Bose-Einstein condensates in\noptical lattices (OL) has been studied in the framework of continuous\nmean-field equation. In 2D and 3D OLs bright matter-wave solitons undergo\nabrupt delocalization as the strength of the OL is decreased below some\ncritical value. Similar delocalizing transition happens when the coefficient of\nnonlinearity crosses the critical value. Contrarily, bright solitons in 1D OLs\nretain their integrity over the whole range of parameter variations. The\ninterpretation of the phenomenon in terms of quantum bound states in the\neffective potential is proposed.",
        "positive": "The asymmetric Wigner bilayer: We present a comprehensive discussion of the so-called asymmetric Wigner\nbilayer system, where mobile point charges, all of the same sign, are immersed\ninto the space left between two parallel, homogeneously charged plates (with\npossibly different charge densities). At vanishing temperatures, the particles\nare expelled from the slab interior; they necessarily stick to one of the two\nplates, and form there ordered sublattices. Using complementary tools (analytic\nand numerical) we study systematically the self-assembly of the point charges\ninto ordered ground state configurations as the inter-layer separation and the\nasymmetry in the charge densities are varied. The overwhelming plethora of\nemerging Wigner bilayer ground states can be understood in terms of the\ncompetition of two strategies of the system: the desire to guarantee net charge\nneutrality on each of the plates and the effort of the particles to\nself-organize into commensurate sublattices. The emerging structures range from\nsimple, highly commensurate (and thus very stable) lattices (such as staggered\nstructures, built up by simple motives) to structures with a complicated\ninternal structure. The combined application of our two approaches (whose\nresults agree within remarkable accuracy) allows to study on a quantitative\nlevel phenomena such as over- and underpopulation of the plates by the mobile\nparticles, the nature of phase transitions between the emerging phases (which\npertain to two different universality classes), and the physical laws that\ngovern the long-range behaviour of the forces acting between the plates.\nExtensive Monte Carlo simulations, which have been carried out at small, but\nfinite temperatures along selected, well-defined pathways in parameter space\nconfirm the analytical and numerical predictions within high accuracy."
    },
    {
        "anchor": "Long-range attraction of particles adhered to lipid vesicles: Many biological systems fold thin sheets of lipid membrane into complex\nthree-dimensional structures. This microscopic origami is often mediated by the\nadsorption and self-assembly of proteins on a membrane. As a model system to\nstudy adsorption-mediated interactions, we study the collective behavior of\nmicrometric particles adhered to a lipid vesicle. We estimate the colloidal\ninteractions using a maximum likelihood analysis of particle trajectories. When\nthe particles are highly wrapped by a tense membrane, we observe strong\nlong-range attractions with a typical binding energy of 150 $k_B T$ and\nsignificant forces extending a few microns.",
        "positive": "Analytical estimate of effective charges at saturation in\n  Poisson-Boltzmann cell models: We propose a simple approximation scheme to compute the effective charge of\nhighly charged colloids (spherical or cylindrical with infinite length). Within\nnon-linear Poisson-Boltzmann theory, we start from an expression of the\neffective charge in the infinite dilution limit which is asymptotically valid\nfor large salt concentrations; this result is then extended to finite colloidal\nconcentration, approximating the salt partitioning effect which relates the\nsalt content in the suspension to that of a dializing reservoir. This leads to\nan analytical expression of the effective charge as a function of colloid\nvolume fraction and salt concentration. These results compare favorably with\nthe effective charges {\\em at saturation} (i.e. in the limit of large bare\ncharge) computed numerically following the standard prescription proposed by\nAlexander {\\it et al.} within the cell model."
    },
    {
        "anchor": "Hard-sphere solids near close packing: Testing theories for\n  crystallization: The freezing transition of hard spheres has been well described by various\nversions of density-functional theory (DFT). These theories should possess the\nclose-packed crystal as a special limit, which represents an extreme testing\nground for the quality of such liquid-state based theories. We therefore study\nthe predictions of DFT for the structure and thermodynamics of the hard-sphere\ncrystal in this limit. We examine the Ramakrishnan-Yussouff (RY) approximation\nand two variants of the fundamental-measure theory (FMT) developed by Rosenfeld\nand coworkers. We allow for general shapes of the density peaks, going beyond\nthe common Gaussian approximation. In all cases we find that, upon approaching\nclose packing, the peak width vanishes proportionally to the free distance a\nbetween the particles and the free energy depends logarithmically on a.\nHowever, different peak shapes and next-to-leading contributions to the free\nenergy result from the different approximate functionals. For the RY theory,\nwithin the Gaussian approximation, we establish that the crystalline solutions\nform a closed loop with a stable and an unstable branch both connected to the\nclose-packing point at a=0, consistent with the absence of a liquid-solid\nspinodal. That version of FMT that has previously been applied to freezing,\npredicts asymptotically step-like density profiles confined to the cells of\nself-consistent cell theory. But a recently suggested improved version which\nemploys tensor weighted densities yields wider and almost Gaussian peaks which\nare shown to be in very good agreement with computer simulations.",
        "positive": "Theory of Ideal Four-Wave Mixing in Bose-Einstein Condensates: Starting from a second-quantized Hamiltonian of many-particle systems, we\nderive the Gross-Pitaevskii (GP) equation in momentum space, which is suitable\nfor studying the multi-wave mixing processes of coherent matter waves. The\ncoupling equations are then applied to study ideal four-wave mixing (4WM), in\nwhich only four waves with definite wavevectors are involved. Some interesting\nproblems of 4WM, such as the phase-matching condition, the collapse and revival\nbehaviour, the effects of relative phase difference, and the conversion\nefficiency are discussed in detail. We also show that the main characters of\nrecent 4WM experiment [Deng et al, Nature 398, 218 (1999)] can be undersood in\nthe present simplified model."
    },
    {
        "anchor": "Anomalous linear elasticity of disordered networks: Continuum elasticity is a powerful tool applicable in a broad range of\nphysical systems and phenomena. Yet, understanding how and on what scales\nmaterial disorder may lead to the breakdown of continuum elasticity is not\nfully understood. We show, based on recent theoretical developments and\nextensive numerical computations, that disordered elastic networks near a\ncritical rigidity transition, such as strain-stiffened fibrous biopolymer\nnetworks that are abundant in living systems, reveal an anomalous long-range\nlinear elastic response below a correlation length. This emergent anomalous\nelasticity, which is non-affine in nature, is shown to feature a qualitatively\ndifferent multipole expansion structure compared to ordinary continuum\nelasticity, and a slower spatial decay of perturbations. The potential degree\nof universality of these results, their implications (e.g. for cell-cell\ncommunication through biological extracellular matrices) and open questions are\nbriefly discussed.",
        "positive": "Bending and Twisting Elasticity: a Revised Marko-Siggia Model on DNA\n  Chirality: A revised Marko-Siggia elastic model for DNA double helix [Macromolecules 27,\n981 (1994)] is proposed, which includes the WLC bending energy and a new chiral\ntwisting energy term. It is predicted that the mean helical repeat length (HRL)\nfor short DNA rings increases with the decreasing of chain length; while for\nvery long chains, their mean HRL is the same, independent of both the chain\nlength and whether the ends are closed, it is longer than the value for\nrectilinear DNAs. Our results are in good agreement with experiments."
    },
    {
        "anchor": "Dynamic Phase Transitions in Coupled Motor Proteins: The effect of interactions on dynamics of coupled motor proteins is\ninvestigated theoretically. A simple stochastic discrete model, that allows to\ncalculate explicitly the dynamic properties of the system, is developed. It is\nshown that there are two dynamic regimes, depending on the interaction between\nthe particles. For strong interactions the motor proteins move as one tight\ncluster, while for weak interactions there is no correlation in the motion of\nthe proteins, and the particle separation increases steadily with time. The\nboundary between two dynamic phases is specified by a critical interaction that\nhas a non-zero value only for the coupling of the asymmetric motor proteins,\nand it depends on the temperature and the transitions rates. At the critical\ninteraction there is a change in a slope for the mean velocities and a\ndiscontinuity in the dispersions of the motor proteins as a function of the\ninteraction energy.",
        "positive": "Shear-enhanced elasticity in the cubic blue phase I: We present results of the linear and non-linear rheology of cubic blue phase\nI (BPI). The elasticity of BPI is dominated by double-twist cylinders assembled\nin a body-centered cubic lattice, which can be specified by disclination lines.\nWe find that the elasticity of BPI is enhanced by an order of magnitude by\napplying pre-shear. The shear-enhanced elasticity is attributed to a\nrearrangement of the disclination lines that are arrested in a metastable\nstate. Our results are relevant for the understanding of the dynamics of\ndisclinations in cubic blue phases."
    },
    {
        "anchor": "Topological defects in cholesteric liquid crystal shells: We investigate experimentally and numerically the defect configurations\nemerging when a cholesteric liquid crystal is confined to a spherical shell. We\nuncover a rich scenario of defect configurations, some of them non-existent in\nnematic shells, where new types of defects are stabilized by the helical\nordering of the liquid crystal. In contrast to nematic shells, here defects are\nnot simple singular points or lines, but have a large structured core.\nSpecifically, we observe five different types of cholesteric shells. We study\nthe statistical distribution of the different types of shells as a function of\nthe two relevant geometrical dimensionless parameters of the system. By playing\nwith these parameters, we are able to induce transitions between different\ntypes of shells. These transitions involve interesting topological\ntransformations in which the defects recombine to form new structures.\nSurprisingly, the defects do not approach each other by taking the shorter\ndistance route (geodesic), but by following intricate paths.",
        "positive": "Generalized Langevin dynamics: Construction and numerical integration of\n  non-Markovian particle-based models: We propose a generalized Langevin dynamics (GLD) technique to construct\nnon-Markovian particle-based coarse-grained models from fine-grained reference\nsimulations and to efficiently integrate them. The proposed GLD model has the\nform of a discretized generalized Langevin equation with distance-dependent\ntwo-particle contributions to the self- and pair-memory kernels. The memory\nkernels are iteratively reconstructed from the dynamical correlation functions\nof an underlying fine-grained system. We develop a simulation algorithm for\nthis class of non-Markovian models that scales linearly with the number of\ncoarse-grained particles. Our GLD method is suitable for coarse-grained studies\nof systems with incomplete time scale separation, as is often encountered,\ne.g., in soft matter systems.\n  We apply the method to a suspension of nanocolloids with frequency-dependent\nhydrodynamic interactions. We show that the results from GLD simulations\nperfectly reproduce the dynamics of the underlying fine-grained system. The\neffective speedup of these simulations amounts to a factor of about $10^4$.\nAdditionally, the transferability of the coarse-grained model with respect to\nchanges of the nanocolloid density is investigated. The results indicate that\nthe model is transferable to systems with nanocolloid densities that differ by\nup to one order of magnitude from the density of the reference system."
    },
    {
        "anchor": "Classical long-range interacting N-particle configurations and its\n  applications: We consider classical N-particle system with arbitrary central pair\npotential. Mechanical equilibrium condition in spherically-symmetric case leads\nto a nonlinear integro-differential equation for concentration n(r). For\nspecial state equation $p=an^{\\gamma}(1+bn)$, original integro-differential\nequation transforms into purely integral one. Its solution (under b=0) is\nwritten through a row over interaction parameter. Physical conditions for its\nconvergency is discussed. For power-like potential kernal of integral operator\nis calculated in apparent kind. The cases of Coulomb and harmonic potentials\nare considered separately up to a third order. General scheme of application of\nthe theory for some astrophysical and cosmological problems is presented. Model\nsystem with spherical potential pits is considered. By perturbation theory\nfirst virial correction $\\delta n$ is calculated.",
        "positive": "Sedimentation of self-propelled Janus colloids: polarization and\n  pressure: We study experimentally-using Janus colloids-and theoretically-using Active\nBrownian Particles- the sedimentation of dilute active colloids. We first\nconfirm the existence of an exponential density profile. We show experimentally\nthe emergence of a polarized steady state outside the effective equilibrium\nregime, i.e. when v_s is not much smaller than the propulsion speed. The\nexperimental distribution of polarization is very well described by the\ntheoretical prediction with no fitting parameter. We then discuss and compare\nthree different definitions of pressure for sedimenting particles: the weight\nof particles above a given height, the flux of momentum and active impulse, and\nthe force density measured by pressure gauges."
    },
    {
        "anchor": "Structure and Stability of Vortices in Dilute Bose-Einstein Condensates\n  at Ultralow Temperatures: We compute the structure of a quantized vortex line in a harmonically trapped\ndilute atomic Bose-Einstein condensate using the Popov version of the\nHartree-Fock-Bogoliubov mean-field theory. The vortex is shown to be\n(meta)stable in a nonrotating trap even in the zero-temperature limit, thus\nconfirming that weak particle interactions induce the condensed gas a\nfundamental property characterizing ``classical'' superfluids. We present the\nstructure of the vortex at ultralow temperatures and discuss the crucial effect\nof the thermal gas component to its energetic stability.",
        "positive": "Isotropic to Nematic Phase Transition in Carbon Nanotube dispersed\n  Liquid Crystal Composites: A high-resolution dielectric and calorimetric study of the isotropic (I) to\nnematic (N) phase transition of carbon nanotube (CNT) dispersed liquid crystal\n(LC) functional composites as a function of CNT concentration is reported. The\nevolution of the I-N phase transition, the temperature dependence of local\nnematic ordering formed by dispersed CNTs in the LC media and the transition\nenthalpy were coherently monitored. Anisotropic CNTs induce local deformation\nto the nematic director of LC and form lyotropic pseudo-nematic phase in the LC\nmedia. Results clearly indicate the dramatic impact of dispersed CNTs on both\nthe isotropic and nematic phases of the composite."
    },
    {
        "anchor": "Topology of Smectic Order on Compact Substrates: Smectic orders on curved substrates can be described by differential forms of\nrank one (1-forms), whose geometric meaning is the differential of the local\nphase field of density modulation. The exterior derivative of 1-form is the\nlocal dislocation density. Elastic deformations are described by superposition\nof exact differential forms. Applying this formalism to study smectic order on\ntorus as well as on sphere, we find that both systems exhibit many\ntopologically distinct low energy states, that can be characterized by two\ninteger topological charges. The total number of low energy states scales as\nthe square root of the substrate area. For smectic on a sphere, we also explore\nthe motion of disclinations as possible low energy excitations, as well as its\ntopological implications.",
        "positive": "Microscopic and continuum descriptions of Janus motor fluid flow fields: Active media, whose constituents are able to move autonomously, display novel\nfeatures that differ from those of equilibrium systems. In addition to\nnaturally-occurring active systems such as populations of swimming bacteria,\nactive systems of synthetic self-propelled nanomotors have been developed.\nThese synthetic systems are interesting because of their potential applications\nin a variety of fields. Janus particles, synthetic motors of spherical geometry\nwith one hemisphere that catalyzes the conversion of fuel to product and one\nnoncatalytic hemisphere, can propel themselves in solution by\nself-diffusiophoresis. In this mechanism the concentration gradient generated\nby the asymmetric catalytic activity leads to a force on the motor that induces\nfluid flows in the surrounding medium. These fluid flows are studied in detail\nthrough microscopic simulations of Janus motor motion and continuum theory. It\nis shown that continuum theory is able to capture many but not all features of\nthe dynamics of the Janus motor and the velocity fields of the fluid."
    },
    {
        "anchor": "Engineering of frustration in colloidal artificial ices realized on\n  microfeatured grooved lattices: Artificial spin ice systems, namely lattices of interacting single domain\nferromagnetic islands, have been used to date as microscopic models of\nfrustration induced by lattice topology, allowing for the direct visualization\nof spin arrangements and textures. However, the engineering of frustrated ice\nstates in which individual spins can be manipulated in situ and the real-time\nobservation of their collective dynamics remain both challenging tasks.\nInspired by recent theoretical advances, here we realize a colloidal version of\nan artificial spin ice system using interacting polarizable particles confined\nto lattices of bistable gravitational traps. We show quantitatively that\nice-selection rules emerge in this frustrated soft matter system by tuning the\nstrength of the pair interactions between the microscopic units. Via\nindependent control of particle positioning and dipolar coupling, we introduce\nmonopole-like defects and strings and use loops with defined chirality as an\nelementary unit to store binary information.",
        "positive": "Overcharging and charge reversal in the electrical double layer near the\n  point of zero charge: The ionic adsorption around a weakly charged spherical colloid, immersed in\nsize-asymmetric 1:1 and 2:2 salts, is studied. We use the primitive model of an\nelectrolyte to perform Monte Carlo simulations as well as theoretical\ncalculations by means of the hypernetted chain/mean spherical approximation\n(HNC/MSA) and the unequal-radius modified Gouy-Chapman (URMGC) integral\nequations. Structural quantities such as the radial distribution functions, the\nintegrated charge, and the mean electrostatic potential are reported. Our Monte\nCarlo \"experiments\" evidence that near the point of zero charge the smallest\nionic species is preferentially adsorbed onto the macroparticle, independently\nof the sign of the charge carried by this tiniest electrolytic component,\ngiving rise to the appearance of the phenomena of charge reversal and\novercharging. Accordingly, charge reversal is observed when the macroion is\nslightly charged and the coions are larger than the counterions. In the\nopposite situation, i.e. if the counterions are larger than the coions,\novercharging occurs. In other words, in this paper we present the first\nsimulational data on overcharging, showing that this novel effect surges close\nto the point of zero charge as a consequence of the ionic size asymmetry.\nFurther, it is seen that the inclusion of hard-core correlations in HNC/MSA\nleads to spatial regions near the macroion's surface in which the integrated\ncharge and/or the mean electrostatic potential can decrease when the colloidal\ncharge is augmented and vice versa. These observations aware about the\ninterpretation of electrophoretic mobility measurements using the standard\nPoisson-Boltzmann approximation beyond its validity region."
    },
    {
        "anchor": "Emergent conformational properties of end-tailored transversely\n  propelling polymers: We study the dynamics and conformations of a single active semiflexible\npolymer whose monomers experience a propulsion force perpendicular to the local\ntangent, with the end beads being different from the inner beads\n(\"end-tailored\"). Using Langevin simulations, we demonstrate that, apart from\nsideways motion, the relative propulsion strength between the end beads and the\npolymer backbone significantly changes the conformational properties of the\npolymers as a function of bending stiffness, end-tailoring and propulsion\nforce. Expectedly, for slower ends the polymer curves away from the moving\ndirection, while faster ends lead to opposite curving, in both cases slightly\nreducing the center of mass velocity compared to a straight fiber.\nInterestingly, for faster end beads there is a rich and dynamic morphology\ndiagram: the polymer ends may get folded together to 2D loops or hairpin-like\nconformations that rotate due to their asymmetry in shape and periodic flapping\nmotion around a rather straight state during full propulsion is also possible.\nWe rationalize the simulations using scaling and kinematic arguments and\npresent the state diagram of the conformations. Sideways propelled fibers\ncomprise a rather unexplored and versatile class of self-propellers, and their\nstudy will open novel ways for designing, e.g. motile actuators or mixers in\nsoft robotics.",
        "positive": "Supersaturated dispersions of rod-like viruses with added attraction: The kinetics of isotropic-nematic (I-N) and nematic-isotropic (N-I) phase\ntransitions in dispersions of rod-like {\\it fd}-viruses are studied.\nConcentration quenches were applied using pressure jumps in combination with\npolarization microscopy, birefringence and turbidity measurements. The full\nbiphasic region could be accessed, resulting in the construction of a first\nexperimental analogue of the bifurcation diagram. The N-I spinodal points for\ndispersions of rods with varying concentrations of depletion agents (dextran)\nwere obtained from orientation quenches, using cessation of shear flow in\ncombination with small angle light scattering. We found that the location of\nthe N-I spinodal point is independent of the attraction, which was confirmed by\ntheoretical calculations. Surprisingly, the experiments showed that also the\nabsolute induction time, the critical nucleus and the growth rate are\ninsensitive of the attraction, when the concentration is scaled to the distance\nto the phase boundaries."
    },
    {
        "anchor": "The stochastic growth of metal whiskers: The phenomenon of spontaneously growing metal whiskers (MW) raises\nsignificant reliability concerns due to its related arcing and shorting in\nelectric equipment. The growth kinetics of MW remains poorly predictable. Here\nwe present a theory describing the earlier observed intermittent growth of MW\nas caused by local energy barriers related to variations in the random electric\nfields generated by surface imperfections. We find the probabilistic\ndistribution of MW stopping times, during which MW growth halts, which is\nimportant for reliability projections.",
        "positive": "Polymer-disordered liquid crystals: Susceptibility to electric field: When nematic liquid crystals are embedded in random polymer networks, the\ndisordered environment disrupts the long-range order, producing a glassy state.\nIf an electric field is applied, it induces large and fairly\ntemperature-independent orientational order. To understand the experiments, we\nsimulate a liquid crystal in a disordered polymer network, visualize the domain\nstructure, and calculate the response to a field. Furthermore, using an\nImry-Ma-like approach we predict the domain size and estimate the field-induced\norder. The simulations and analytic results agree with each other, and suggest\nhow the materials can be optimized for electro-optic applications."
    },
    {
        "anchor": "Hydrogen Bond Networks Near Supported Lipid Bilayers from Vibrational\n  Sum Frequency Generation Experiments and Atomistic Simulations: We report vibrational sum frequency generation spectra from supported lipid\nbilayers in which the OH and the CH stretching signals are probed at different\nsalt concentrations. Atomistic simulations show a negligible impact of salt on\nthe OH stretching spectra, indicating the observed SFG intensity changes are\ndue to chi(3) and potential dependent contributions. These are further analyzed\nin the contact of exact-zero reference states. Further experiments and\nsimulations identify specific hydrogen bonding interactions between interfacial\nwater molecules at the PC head group of the zwitterionic DMPC lipids at 3200\nwavenumbers.",
        "positive": "Photoactive Gold Nanoparticle Soft-oxometalates (SOM) using a Keplerate\n  for Synthesis of Polystyrene Latex Microspheres by Photo-polymerization: A green and facile synthetic protocol for the preparation of photoactive gold\nnanoparticle-soft oxometalates (AuNP-SOM) using a unique Keplarate type\noxomolybdate cluster viz. {Mo$_{132}$}, is reported. The as synthesized\nAuNP-SOMs are fully characterized by Electronic absorption spectroscopy, Raman\nspectroscopy and High resolution transmission electron microscopy (HR-TEM). We\nfurther demonstrate that by merely tuning the ratio of the precursors in\nsolution it is possible to control the morphology of AuNP-SOM nanostructures.\nMoreover, these photoactive AuNP-SOMs are employed as photocatalysts for the\nphotopolymerization of styrene to generate colloidal monodisperse polystyrene\nmicrospheres in a controllable way in the absence of any external co-initiator\nor inert atmosphere. Effect of styrene concentration on the size of\nmicrospheres is studied using DLS and optical microscopy. Finally, the role of\nAuNP-SOMs as efficient photocatalyst is established through several control\nexperiments and a reaction pathway is proposed."
    },
    {
        "anchor": "A simulation study of homogeneous ice nucleation in supercooled salty\n  water: We use computer simulations to investigate the effect of salt on homogeneous\nice nucleation. The melting point of the employed solution model was obtained\nboth by direct coexistence simulations and by thermodynamic integration from\nprevious calculations of the water chemical potential.\n  Using a Seeding approach, in which we simulate ice seeds embedded in a\nsupercooled aqueous solution, we compute the nucleation rate as a function of\ntemperature for a 1.85 NaCl mole per water kilogram solution at 1 bar. To\nimprove the accuracy and reliability of our calculations we combine Seeding\nwith the direct computation of the ice-solution interfacial free energy at\ncoexistence using the Mold Integration method. We compare the results with\nprevious simulation work on pure water to understand the effect caused by the\nsolute. The model captures the experimental trend that the nucleation rate at a\ngiven supercooling decreases when adding salt. Despite the fact that the\nthermodynamic driving force for ice nucleation is higher for salty water for a\ngiven supercooling, the nucleation rate slows down with salt due to a\nsignificant increase of the ice-fluid interfacial free energy. The salty water\nmodel predicts an ice nucleation rate that is in good agreement with\nexperimental measurements, bringing confidence in the predictive ability of the\nmodel.",
        "positive": "A Solid-State System for High Temporal Resolution Fluorescence Lifetime\n  Measurements: A system for time-correlated single photon counting applications based on\nCMOS single photon avalanche diodes is presented. An instrument response\nfunction of 79 ps allows a fluorescence decay of high-affinity Ca2+ indicator\nOregon Green BAPTA-1 to be analyzed with unprecedented temporal resolution in\nthe two-photon excitation regime. A triple exponential decay model is shown to\nbest fit the fluorescence dynamics of OGB-1."
    },
    {
        "anchor": "Shear thickening and jamming in densely packed suspensions of different\n  particle shapes: We investigated the effects of particle shape on shear thickening in densely\npacked suspensions. Rods of different aspect ratios and non-convex hooked rods\nwere fabricated. Viscosity curves and normal stresses were measured using a\nrheometer for a wide range of packing fractions for each shape. Suspensions of\neach shape exhibit qualitatively similar Discontinuous Shear Thickening. The\nlogarithmic slope of the stress/shear-rate relation increases dramatically with\npacking fraction and diverges at a critical packing fraction phi_c which\ndepends on particle shape. The packing fraction dependence of the viscosity\ncurves for different convex shapes can be collapsed when the packing fraction\nis normalized by phi_c. Intriguingly, viscosity curves for non-convex particles\ndo not collapse on the same set as convex particles, showing strong shear\nthickening over a wider range of packing fraction. The value of phi_c is found\nto coincide with the onset of a yield stress at the jamming transition,\nsuggesting the jamming transition also controls shear thickening. The yield\nstress is found to correspond with trapped air in the suspensions, and the\nscale of the stress can be attributed to interfacial tension forces which\ndramatically increase above phi_c due to the geometric constraints of jamming.\nThe relationship between shear and normal stresses is found to be linear in\nboth the shear thickening and jammed regimes, indicating that the shear\nstresses come from friction. In the limit of zero shear rate, normal stresses\npull the rheometer plates together due to the surface tension of the liquid\nbelow phi_c, but push the rheometer plates apart due to jamming above phi_c.",
        "positive": "Disappearance of a Stacking Fault in Hard-Sphere Crystals under Gravity: In the first part of this paper, a review is given on the mechanism for the\ndisappearance of an intrinsic stacking fault in a hard-sphere (HS) crystal\nunder gravity, which we recently discovered by Monte Carlo (MC) simulations [A.\nMori et al., J. Chem. Phys., 124 (2006), 17450; Mol. Phys. 105 (2007), 1377].\nWe have observed, in the case of fcc (001) stacking, that the intrinsic\nstacking fault running along an oblique direction shrunk through the gliding of\na Shockley partial dislocation at the lower end of the stacking fault. In order\nto address the shortcomings and approximations of previous simulations, such as\nthe use of periodic boundary condition (PBC) and the fact that the fcc (001)\nstacking had been realized by the stress from the small PBC box, we present an\nelastic strain energy calculation for an infinite system and a MC simulation\nresult for HSs in a pyramidal pit under gravity. In particular, the geometry of\nthe latter has already been tested experimentally [S. Matsuo et al., Appl.\nPhys. Lett., 82 (2003), 4283]. The advantage of using a pyramidal pit as a\ntemplate as well as the feasibility of the mechanism we describe is\ndemonstrated."
    },
    {
        "anchor": "Dynamic and Dielectric Response of Charged Colloids in Electrolyte\n  Solutions to External Electric Fields: Computer simulations are used to investigate the response of a charged\ncolloid and its surrounding microion cloud to an external electric field. Both\nstatic fields (DC) and alternating fields (AC) are considered. A mesoscopic\nsimulation method is implemented to account in full for hydrodynamic and\nelectrostatic interactions. The response of the system can be characterized by\ntwo quantities: the mobility and the polarizability. Due to the interplay of\nthe electrostatic attraction and hydrodynamic drag, the response of the\nmicroions close to the colloid surface is different from that of the microions\nfar away from the colloid. Both the mobility and polarizability exhibit a\ndependency on the frequency of the external fields, which can be attributed to\nthe concentration polarization, the mobility of the microions, and the inertia\nof microions. The effects of the colloidal charge, the salt concentration, and\nthe frequency of the external fields are investigated systematically.",
        "positive": "Critical Casimir effect in classical binary liquid mixtures: If a fluctuating medium is confined, the ensuing perturbation of its\nfluctuation spectrum generates Casimir-like effective forces acting on its\nconfining surfaces. Near a continuous phase transition of such a medium the\ncorresponding order parameter fluctuations occur on all length scales and\ntherefore close to the critical point this effect acquires a universal\ncharacter, i.e., to a large extent it is independent of the microscopic details\nof the actual system. Accordingly it can be calculated theoretically by\nstudying suitable representative model systems.\n  We report on the direct measurement of critical Casimir forces by total\ninternal reflection microscopy (TIRM), with femto-Newton resolution. The\ncorresponding potentials are determined for individual colloidal particles\nfloating above a substrate under the action of the critical thermal noise in\nthe solvent medium, constituted by a binary liquid mixture of water and\n2,6-lutidine near its lower consolute point. Depending on the relative\nadsorption preferences of the colloid and substrate surfaces with respect to\nthe two components of the binary liquid mixture, we observe that, upon\napproaching the critical point of the solvent, attractive or repulsive forces\nemerge and supersede those prevailing away from it. Based on the knowledge of\nthe critical Casimir forces acting in film geometries within the Ising\nuniversality class and with equal or opposing boundary conditions, we provide\nthe corresponding theoretical predictions for the sphere-planar wall geometry\nof the experiment. The experimental data for the effective potential can be\ninterpreted consistently in terms of these predictions and a remarkable\nquantitative agreement is observed."
    },
    {
        "anchor": "Simulations of Coulombic Fission of Charged Inviscid Drops: We present boundary-integral simulations of the evolution of critically\ncharged droplets. For such droplets, small ellipsoidal perturbations are\nunstable and eventually lead to the formation of a \"lemon\"-shaped drop with\nvery sharp tips. For perfectly conducting drops, the tip forms a self-similar\ncone shape with a subtended angle identical to that of a Taylor cone. At the\ntip, quantities such and pressure and fluid velocity diverge in time with\npower-law scaling. In contrast, when charge transport is described by a finite\nconductivity, we find that small progeny drops are formed at the tips whose\nsize decreases as the conductivity is increased. These small progeny drops are\nof nearly critical charge, and are precursors to the emission of a sustained\nflow of liquid from the tips as observed in experiments of isolated charged\ndrops.",
        "positive": "Efficient shapes for microswimming: from three-body swimmers to helical\n  flagella: We combine a general formulation of microswimmmer equations of motion with a\nnumerical bead-shell model to calculate the hydrodynamic interactions with the\nfluid, from which the swimming speed, power and efficiency are extracted. From\nthis framework, a generalized Scallop Theorem emerges. The applicability to\narbitrary shapes allows for the optimization of the efficiency with respect to\nthe swimmer geometry. We apply this scheme to `three-body swimmers' of various\nshapes and find that the efficiency is characterized by the single body\nfriction coefficient in the long-arm regime, while in the short-arm regime the\nminimal approachable distance becomes the determining factor. Next, we apply\nthis scheme to a biologically inspired swimmer that propels itself using a\nrotating helical flagellum. Interestingly, we find two distinct optimal shapes,\none of which is fundamentally different from the shapes observed in nature\n(e.g. bacteria)."
    },
    {
        "anchor": "Anomalous transport resolved in space and time by fluorescence\n  correlation spectroscopy: A ubiquitous observation in crowded cell membranes is that molecular\ntransport does not follow Fickian diffusion but exhibits subdiffusion. The\nmicroscopic origin of such a behaviour is not understood and highly debated.\nHere we discuss the spatio-temporal dynamics for two models of subdiffusion:\nfractional Brownian motion and hindered motion due to immobile obstacles. We\nshow that the different microscopic mechanisms can be distinguished using\nfluorescence correlation spectroscopy (FCS) by systematic variation of the\nconfocal detection area. We provide a theoretical framework for space-resolved\nFCS by generalising FCS theory beyond the common assumption of spatially\nGaussian transport. We derive a master formula for the FCS autocorrelation\nfunction, from which it is evident that the beam waist of an FCS experiment is\na similarly important parameter as the wavenumber of scattering experiments.\nThese results lead to scaling properties of the FCS correlation for both\nmodels, which are tested by in silico experiments. Further, our scaling\nprediction is compatible with the FCS half-value times reported by Wawrezinieck\net al. [Biophys. J. 89, 4029 (2005)] for in vivo experiments on a transmembrane\nprotein.",
        "positive": "Approximate analytical description of the nonaffine response of\n  amorphous solids: An approximation scheme for model disordered solids is proposed that leads to\nthe fully analytical evaluation of the elastic constants under explicit account\nof the inhomogeneity (nonaffinity) of the atomic displacements. The theory is\nin quantitative agreement with simulations for central-force systems and\npredicts the vanishing of the shear modulus at the isostatic point with the\nlinear law {\\mu} ~ (z - 2d), where z is the coordination number. The vanishing\nof rigidity at the isostatic point is shown to be a consequence of the\ncanceling out of positive affine and negative nonaffine terms."
    },
    {
        "anchor": "Counterion-controlled phase equilibria in a charge-regulated polymer\n  solution: We study phase equilibria in a minimal model of charge-regulated polymer\nsolutions. Our model consists of a single polymer species whose charge state\narises from protonation-deprotonation processes in the presence of a dissolved\nacid, whose anions serve as screening counterions. We explicitly account for\nvariability in the polymers' charge states. Homogeneous equilibria in this\nmodel system are characterised by the total concentration of polymers, the\nconcentration of counter-ions and the charge distributions of polymers which\ncan be computed with the help of analytical approximations. We use these\nanalytical results to characterise how parameter values and solution acidity\ninfluence equilibrium charge distributions and identify for which regimes\nuni-modal and multi-modal charge distributions arise. We then study the\ninterplay between charge regulation, solution acidity and phase separation. We\nfind that charge regulation has a significant impact on polymer solubility and\nallows for non-linear responses to the solution acidity: re-entrant phase\nbehaviour is possible in response to increasing solution acidity. Moreover, we\nshow that phase separation can yield to the coexistence of local environments\ncharacterised by different charge distributions and mixture compositions.",
        "positive": "Rheological constitutive equation for model of soft glassy materials: We solve exactly and describe in detail a simplified scalar model for the low\nfrequency shear rheology of foams, emulsions, slurries, etc. [P. Sollich, F.\nLequeux, P. Hebraud, M.E. Cates, Phys. Rev. Lett. 78, 2020 (1997)]. The model\nattributes similarities in the rheology of such ``soft glassy materials'' to\nthe shared features of structural disorder and metastability. By focusing on\nthe dynamics of mesoscopic elements, it retains a generic character.\nInteractions are represented by a mean-field noise temperature x, with a glass\ntransition occurring at x=1 (in appropriate units). The exact solution of the\nmodel takes the form of a constitutive equation relating stress to strain\nhistory, from which all rheological properties can be derived. For the linear\nresponse, we find that both the storage modulus G' and the loss modulus G''\nvary with frequency as \\omega^{x-1} for 1<x<2, becoming flat near the glass\ntransition. In the glass phase, aging of the moduli is predicted. The steady\nshear flow curves show power law fluid behavior for x<2, with a nonzero yield\nstress in the glass phase; the Cox-Merz rule does not hold in this\nnon-Newtonian regime. Single and double step strains further probe the\nnonlinear behavior of the model, which is not well represented by the BKZ\nrelation. Finally, we consider measurements of G' and G'' at finite strain\namplitude \\gamma. Near the glass transition, G'' exhibits a maximum as \\gamma\nis increased in a strain sweep. Its value can be strongly overestimated due to\nnonlinear effects, which can be present even when the stress response is very\nnearly harmonic. The largest strain \\gamma_c at which measurements still probe\nthe linear response is predicted to be roughly frequency-independent."
    },
    {
        "anchor": "Excitation and damping of collective modes of a Bose-Einstein condensate\n  in a one-dimensional lattice: The mode structure of a Bose-Einstein condensate non-adiabatically loaded\ninto a one-dimensional optical lattice is studied by analyzing the visibility\nof the interference pattern as well as the radial profile of the condensate\nafter a time-of-flight. A simple model is proposed that predicts the short-time\ndecrease of the visibility as a function of the condensate parameters. In the\nradial direction, heavily damped oscillations are observed, as well as an\nincrease in the condensate temperature. These findings are interpreted as a\nre-thermalization due to dissipation of the initial condensate excitations into\nhigh-lying modes.",
        "positive": "Contact lines for fluid surface adhesion: When a fluid surface adheres to a substrate, the location of the contact line\nadjusts in order to minimize the overall energy. This adhesion balance implies\nboundary conditions which depend on the characteristic surface deformation\nenergies. We develop a general geometrical framework within which these\nconditions can be systematically derived. We treat both adhesion to a rigid\nsubstrate as well as adhesion between two fluid surfaces, and illustrate our\ngeneral results for several important Hamiltonians involving both curvature and\ncurvature gradients. Some of these have previously been studied using very\ndifferent techniques, others are to our knowledge new. What becomes clear in\nour approach is that, except for capillary phenomena, these boundary conditions\nare not the manifestation of a local force balance, even if the concept of\nsurface stress is properly generalized. Hamiltonians containing higher order\nsurface derivatives are not just sensitive to boundary translations but also\nnotice changes in slope or even curvature. Both the necessity and the\nfunctional form of the corresponding additional contributions follow readily\nfrom our treatment."
    },
    {
        "anchor": "Polaron tunneling dynamics in the DNA molecule: The formation of polaron and its migration in a DNA chain are studied within\na semiclassical Peyrard-Biship-Holstein polaron model. Comparing the energetics\nof the polaron system found from the quantum chemical and semiclassical\ncalculations, we extract the charge-phonon coupling constant for poly DNA\nsequences. The coupling constant is found to be larger for the G-C than for the\nA-T pairs. With this coupling constant we study tunneling in the DNA molecule.\nThe rates and the nature of tunneling have strong dependence on the DNA\nsequence. By changing the trap positions in the molecular bridge the tunneling\nrate can by varied up to seven orders of magnitude.",
        "positive": "Thermodynamic Approach to Phase Coexistence in Ternary\n  Phospholipi-Cholesterol Mixtures: We introduce a simple and predictive model for determining the phase\nstability of ternary phospholipid-cholesterol mixtures. Assuming that\ncompetition between the liquid and gel order of the phospholipids is the main\ndriving force behind lipid segregation, we derive a Gibbs free-energy of\nmixing, based on the thermodynamic properties of the lipids main transition. A\nnumerical approach was devised that enable the fast and efficient determination\nof the ternary diagrams associated with our Gibbs free-energy. The computed\nphase coexistence diagram of DOPC/DPPC/cholesterol reproduces well known\nfeatures for this system at 10\\circ C, as well as its evolution with\ntemperature."
    },
    {
        "anchor": "Computing equilibrium states of cholesteric liquid crystals in\n  elliptical channels with deflation algorithms: We study the problem of a cholesteric liquid crystal confined to an\nelliptical channel. The system is geometrically frustrated because the\ncholesteric prefers to adopt a uniform rate of twist deformation, but the\nelliptical domain precludes this. The frustration is resolved by deformation of\nthe layers or introduction of defects, leading to a particularly rich family of\nequilibrium configurations. To identify the solution set, we adapt and apply a\nnew family of algorithms, known as deflation methods, that iteratively modify\nthe free energy extremisation problem by removing previously known solutions. A\nsecond algorithm, deflated continuation, is used to track solution branches as\na function of the aspect ratio of the ellipse and preferred pitch of the\ncholesteric.",
        "positive": "Reversible signal transmission in an active mechanical metamaterial: Mechanical metamaterials are designed to enable unique functionalities, but\nare typically limited by an initial energy state and require an independent\nenergy input to function repeatedly. Our study introduces a theoretical active\nmechanical metamaterial that incorporates a biological reaction mechanism to\novercome this key limitation of passive metamaterials. Our material allows for\nreversible mechanical signal transmission, where energy is reintroduced by the\nbiologically motivated reaction mechanism. By analysing a coarse grained\ncontinuous analogue of the discrete model, we find that signals can be\npropagated through the material by a travelling wave. Analysis of the continuum\nmodel provides the region of the parameter space that allows signal\ntransmission, and reveals similarities with the well-known FitzHugh-Nagumo\nsystem. We also find explicit formulae that approximate the effect of the\ntimescale of the reaction mechanism on the signal transmission speed, which is\nessential for controlling the material."
    },
    {
        "anchor": "Driven particles at fluid interfaces acting as capillary dipoles: The dynamics of spherical particles driven along an interface between two\nimmiscible fluids is investigated asymptotically. Under the assumptions of a\npinned three-phase contact line and very different viscosities of the two\nfluids, a particle assumes a tilted orientation. As it moves, it causes a\ndeformation of the fluid interface which is also computed. The case of two\ninteracting driven particles is studied via the Linear Superposition\nApproximation. It is shown that the capillary interaction force resulting from\nthe particle motion is dipolar in terms of the azimuthal angle and decays with\nthe fifth power of the inter-particle separation, similar to a capillary\nquadrupole originating from undulations of the three-phase contact line. The\ndipolar interaction is demonstrated to exceed the quadrupolar interaction at\nmoderate particle velocities.",
        "positive": "Stress relaxation, dynamics and plasticity of transient polymer networks: We propose a theoretical framework for dealing with a transient polymer\nnetwork undergoing small deformations, based on the rate of breaking and\nre-forming of network crosslinks and the evolving elastic reference state. In\nthis framework, the characteristics of the deformed transient network at\nmicroscopic and macroscopic scales are naturally unified. Microscopically, the\nbreakage rate of the crosslinks is affected by the local force acting on the\nchain. Macroscopically, we use the classical continuum model for rubber\nelasticity to describe the structure of the deformation energy, whose reference\nstate is defined dynamically according to when crosslinks are broken and\nformed. With this, the constitutive relation can be obtained. We study three\napplications of the theory in uniaxial stretching geometry: for the stress\nrelaxation after an instantaneous step strain is imposed, for the stress\novershoot and subsequent decay in the plastic regime when a strain ramp is\napplied, and for the cycle of stretching and release. We compare the model\npredictions with experimental data on stress relaxation and stress overshoot in\nphysically bonded thermoplastic elastomers and in vitrimer networks."
    },
    {
        "anchor": "Crystal nucleation in a vapor deposited Lennard-Jones mixture: Understanding the pathways to crystallization during the deposition of a\nvapor phase on a cold solid substrate is of great interest in industry, e.g.,\nfor the realization of electronic devices made of crystallites-free glassy\nmaterials, as well as in the atmospheric science in relation to ice nucleation\nand growth in clouds. Here we numerically investigate the nucleation process\nduring the deposition of a glassformer by using a Lennard-Jones mixture, and\ncompare the properties of this nucleation process with both its quenched\ncounterpart and the bulk system. We find that all three systems homogeneously\nnucleate crystals in a narrow range of temperatures. However, the deposited\nlayer shows a peculiar formation of ordered domains, promoted by the faster\nrelaxation dynamics toward the free surface even in an as-deposited state. In\ncontrast, the formation of such domains in the other systems occurs only when\nthe structures are fully relaxed by quenching. Furthermore, the nucleus\ninitially grows in an isotropic symmetrical manner, but eventually shows sub-3D\ngrowth due to its preference to grow along the basal plane, irrespective of the\nlayer production procedure.",
        "positive": "Spatial structure and aggregation of carbon allotrope nanofillers in\n  isotactic polypropylene composites studied by small-angle neutron scattering: We study the aggregation of carbon allotrope nanofillers in the matrix of\nisotactic polypropylene with direct small-angle neutron scattering\nmeasurements. With the ATSAS software, we analyzed the data and determined the\nfractal shape, dimension, and sizes of nanofiller aggregation in the bulk of\nisotactic polypropylene over the range of the scattering angles. We estimated\nthe volume distributions and aggregation of different types of carbon\nnanofillers at different concentrations: nanographite, graphene nanoplatelets\n(GNP), single-walled carbon nanotubes (SWCNT), multi-wall carbon nanotubes\n(MWCNT), binary fillers MWCNT/GNP and fullerenes. We reconstructed the shape of\nnanoscale aggregates of all nanofillers and found that the systems are\npolydisperse; nanofillers associate in the volume of iPP as fractal dense\naggregates with rugged surface, their sizes exceeding original dimensions of\nnanofillers several times."
    },
    {
        "anchor": "Fluctuations and the Effective Moduli of an Isotropic, Random Aggregate\n  of Identical, Frictionless Spheres: We consider a random aggregate of identical frictionless elastic spheres that\nhas first been subjected to an isotropic compression and then sheared. We\nassume that the average strain provides a good description of how stress is\nbuilt up in the initial isotropic compression. However, when calculating the\nincrement in the displacement between a typical pair of contaction particles\ndue to the shearing, we employ force equilibrium for the particles of the pair,\nassuming that the average strain provides a good approximation for their\ninteractions with their neighbors. The incorporation of these additional\ndegrees of freedom in the displacement of a typical pair relaxes the system,\nleading to a decrease in the effective moduli of the aggregate. The\nintroduction of simple models for the statistics of the ordinary and\nconditional averages contributes an additional decrease in moduli. The\nresulting value of the shear modulus is in far better agreement with that\nmeasured in numerical simulations.",
        "positive": "Microstructural rearrangements and their rheological implications in a\n  model Thixotropic Elasto-Visco-Plastic (TEVP) fluid: We identify the sequence of microstructural changes that characterize the\nevolution of an attractive particulate gel under flow and discuss their\nimplications on macroscopic rheology. Dissipative Particle Dynamics (DPD) is\nused to monitor shear-driven evolution of a fabric tensor constructed from the\nensemble spatial configuration of individual attractive constituents within the\ngel. By decomposing this tensor into isotropic and non-isotropic components we\nshow that the average coordination number correlates directly with the flow\ncurve of the shear stress vs. shear rate, consistent with theoretical\npredictions for attractive systems. We show that the evolution in non-isotropic\nlocal particle rearrangements are primarily responsible for stress overshoots\n(strain-hardening) at the inception of steady shear flow and also lead, at\nlarger times and longer scales, to microstructural localization phenomena such\nas shear banding flow-induced structure formation in the vorticity direction."
    },
    {
        "anchor": "Properties of Poly (isoprene) - Model Building in the Melt and in\n  Solution: Properties of 1,4-\\textit{trans} poly (isoprene) at ambient conditions are\ndetermined by simulations on two length scales based on two different models: a\nfull-atomistic and a mesoscopic one. The models are linked via a mapping scheme\nsuch that one mesoscopic bead represents one chemical repeat unit. Melts as\nwell as solutions of several chain lengths were investigated and mapped\nindividually to the meso-scale. The resulting models are compared to each\nother. The meso-scale models could be simulated over a large variety of chain\nlengths and time-scales relevant for experimental comparison. Concerning static\nproperties, we determined the persistence length of our systems and the scaling\nbehavior of the radius of gyration. The latter was compared to experiments and\nthe agreement is satisfactory. Furthermore, we find deviations from Rouse\ndynamics at all chain lengths at ambient conditions.",
        "positive": "Glass-like dynamics of the strain-induced coil/helix transition on a\n  permanent polymer network: We study the stress response to a step strain of covalently bonded gelatin\ngels in the temperature range where triple helix reversible crosslink formation\nis prohibited. We observe slow stress relaxation towards a $T$-dependent finite\nasymptotic level. We show that this is assignable to the strain-induced coil\n$\\rightarrow$ helix transition, previously evidenced by S. Courty, J.L. Gornall\nand E.M. Terentjev (PNAS, {\\bf 102}, 13453 (2005)), of a fraction of the\npolymer strands. Relaxation proceeds, in a first stage, according to a\nstretched exponential dynamics, then crosses over to a terminal simple\nexponential decay. The respective characteristic times $\\tau_{K}$ and\n$\\tau_{f}$ exhibit an Arrhenius-like $T$-dependence with an associated energy\n$\\cal E$ incompatibly larger than the activation barrier height for the\nisomerisation process which sets the clock for an elementary coil $\\to$ helix\ntransformation event. We tentatively assign this glass-like slowing down of the\ndynamics to the long-range couplings due to the mechanical noise generated by\nthe local elementary events in this random elastic medium."
    },
    {
        "anchor": "Entropons as collective excitations in active solids: The vibrational dynamics of solids is described by phonons constituting basic\ncollective excitations in equilibrium crystals. Here we consider an active\ncrystal composed of self-propelled particles which bring the system into a\nnon-equilibrium steady-state governed by entropy production. Calculating the\nentropy production spectrum, we put forward the picture of \"entropons\", which\nare vibrational collective excitations responsible for entropy production.\nEntropons are purely generated by activity and coexist with phonons but\ndominate over them for large self-propulsion strength. The existence of\nentropons can be verified in experiments on dense self-propelled colloidal\nJanus-particles and granular active matter, as well as in living systems such\nas dense cell monolayers.",
        "positive": "A coupled map lattice model for spontaneous pore formation in anodic\n  oxidation: We construct a coupled map lattice model for the spontaneous pore formation\nin anodic oxidation in two dimensions and perform numerical simulations, after\nwe explain steady flat solutions, their linear stability and a single pore\nsolution for a model of Parkhutik and Shershulsky."
    },
    {
        "anchor": "On the behaviour of short Kratky-Porod chain: Using the exact computation of a large number of moments of the distribution\nfunction of the end-to-end distance $G(r,N)$ of the worm-like chain, we have\nestablished the analytical form of the coefficients in Taylor expansions of the\nmoments for short chain lengths $N$. The knowledge of these coefficients\nenabled us to resummate the moment expansion of $G(r,N)$ by taking into account\nconsecutively the deviations of the moments from their stiff rod limit. Within\nthis procedure we have derived the short chain expansion for $G(r,N)$, the\nscattering function, and the extension-force relation, which take into account\nthe deviations of the moments from their stiff rod limit to the seventh order\nin $N$.",
        "positive": "Spatial cooperativity in microchannel flows of soft jammed materials: A\n  mesoscopic approach: The flow of amorphous solids results from a combination of elastic\ndeformation and local structural rearrangements, which induce non-local elastic\ndeformations. These elements are incorporated into a mechanically-consistent\nmesoscopic model of interacting elastoplastic blocks. We investigate the\nspecific case of channel flow with numerical simulations, paying particular\nattention to situations of strong confinement. We find that the simple picture\nof plastic events embedded in an elastic matrix successfully accounts for\nmanifestations of spatial cooperativity. Shear rate fluctuations are observed\nin seemingly quiescent regions, and the velocity profiles in confined flows at\nhigh applied pressure deviate from those expected in the absence of non-local\neffects, in agreement with experimental data. However, we suggest a different\nphysical origin for the large deviations observed when walls have rough\nsurfaces, associated with \"bumps\" of the particles against the asperities of\nthe walls."
    },
    {
        "anchor": "Collapse of superhydrophobicity on nanopillared surfaces: The mechanism of the collapse of the superhydrophobic state is elucidated for\nsubmerged nanoscale textures forming a three-dimensional interconnected vapor\ndomain. This key issue for the design of nanotextures poses significant\nsimulation challenges as it is characterized by diverse time and length scales.\nState-of-the-art atomistic rare events simulations are applied for overcoming\nthe long time scales connected with the large free energy barriers. In such\ninterconnected surface cavities wetting starts with the formation of a liquid\nfinger between two pillars. This break of symmetry induces a more gentle bend\nin the rest of the liquid-vapor interface, which triggers the wetting of the\nneighboring pillars. This collective mechanism, involving the wetting of\nseveral pillars at the same time, could not be captured by previous atomistic\nsimulations using surface models comprising a small number of pillars (often\njust one). Atomistic results are interpreted in terms of a sharp-interface\ncontinuum model which suggests that line tension, condensation, and other\nnanoscale phenomena play a minor role in the simulated conditions.",
        "positive": "Correlated orientational disorder in entropic crystals: We report computational evidence for a new type of disordered phase in\ncrystals resulting from entropy driven self-assembly of hard convex polyhedra.\nThe disorder was reflected in the orientations of the anisotropic particles and\nnot in the positions of the centers of geometry. Despite the lack of order,\nparticle orientations were not random, and exhibited strong correlations. The\norientational correlations possessed certain special properties that remained\nconstant across the pressure range where this phase was observed. The\nrotational motions of all particles became discrete, characterized by a fixed\nnumber of absolute orientations. The particles were equally partitioned among\nthem at all time, while maintaining specific values of pairwise orientational\ndifferences. The sense of ``order'' in the disorder was conserved irrespective\nof the extent of rotational mobility of the particles. This gave rise to a\ndiscretely mobile phase in the low density solid and a frozen disordered state\nat high pressure. The newly identified ``discrete plastic crystal'' phase\ntransitioned into a freely rotating one, where rotational degrees of freedom\nwere completely random. The resulting solid-solid transition was purely\norientational in nature without the change in the face centered cubic\ncrystalline arrangements of the centers of the anisotropic particles. This\nfinding can be interpreted as the simplest example of correlated disorder in\ncolloidal crystals."
    },
    {
        "anchor": "Local Plastic Response and Slow Heterogeneous Dynamics of Supercooled\n  Liquids: We demonstrate, via numerical simulations, that the relaxation dynamics of\nsupercooled liquids correlates well with a plastic length scale measuring a\nparticle's response to impulsive localized perturbations and weakly to measures\nof local elasticity. We find that the particle averaged plastic length scale\nvanishes linearly in temperature and controls the super-Arrhenius temperature\ndependence of the relaxation time. Furthermore, we show that the plastic length\nscale of individual particles correlates with their typical displacement at the\nrelaxation time. In contrast, the local elastic response only correlates with\nthe dynamics on the vibrational time scale.",
        "positive": "Multiparticle Collision Dynamics for Tensorial Nematodynamics: Liquid crystals establish a nearly unique combination of thermodynamic,\nhydrodynamic, and topological behavior. This poses a challenge to their\ntheoretical understanding and modeling. The arena where these effects come\ntogether is the mesoscopic (micron) scale. It is then important to develop\nmodels aimed at capturing this variety of dynamics. We have generalized the\nparticle-based multiparticle collision dynamics (MPCD) method to model the\ndynamics of nematic liquid crystals. Following the Qian--Sheng theory of\nnematics, the spatial and temporal variations of the nematic director field and\norder parameter are described by a tensor order parameter. The key idea is to\nassign tensorial degrees of freedom to each MPCD particle, whose mesoscopic\naverage is the tensor order parameter. This new nematic-MPCD method includes\nbackflow effect, velocity-orientation coupling and thermal fluctuations. We\nvalidate the applicability of this method by testing: (i) the nematic-isotropic\nphase transition, (ii) the flow alignment of the director in shear and\nPoiseuille flows, and (iii) the annihilation dynamics of a pair of line\ndefects. We find excellent agreement with existing literature. We also\ninvestigate the flow field around a force dipole in a nematic liquid crystal,\nwhich represents the leading-order flow field around a force-free microswimmer.\nThe anisotropy of the medium not only affects the magnitude of velocity field\naround the force dipole, but can also induce hydrodynamic torques depending on\nthe orientation of dipole axis relative to director field. A force dipole\nexperiences a hydrodynamic torque when the dipole axis is tilted with respect\nto the far-field director. The direction of hydrodynamic toque is such that the\npusher- (or puller-) type force dipole tends to orient along (or perpendicular\nto) the director field."
    },
    {
        "anchor": "Mechanisms of Cooperation and Competition of two Species Transport in\n  Narrow Nanochannels: Flow of particles of two different species through a narrow channel with\nsolely two discrete spatial positions is analyzed with respect to the species'\ncapability to cooperate or compete for transport. In contrast to mean field\napproaches, spatial correlations are explicitly conserved. A strong repulsive\ninteraction between particles of the same kind and a very attractive channel\nimply a strong entanglement of transport of both species. This is reflected by\nthe magnitude of transition flows in state space which in the extreme case of\nperfect coupling are restricted to a cyclic sub space. Entanglement of\ntransport implies that the species mutually exert entropic forces on each\nother. For parallel directed concentration gradients this implies that the\nspecies' ability to cooperate increases with the degree of entanglement. Thus,\nthe gradient of one species reciprocally induce a higher flow of the other\nspecies when compared to that in its absence. The opposite holds for\nantiparallel gradients where species mutually hamper their transport. For a\nsufficient strong coupling, the species under the influence of the stronger\nconcentration gradient drives the other against its gradient, i.e. flow and\ngradient of the driven species become antiparallel. Hence, besides the positive\nentropy production generated by the driving species a negative component of\nentropy production of the driven species emerges. The sources of both, positive\nand negative entropy production, can be localized in state space. The stronger\nthe coupling of transport the higher is the degree of efficiency, i.e. the\namount of negative entropy production on cost of the positive one.",
        "positive": "Micro- and nanoscale fluid flow on chemical channels: We study the time evolution and driven motion of thin liquid films lying on\ntop of chemical patterns on a substrate. Lattice-Boltzmann and molecular\ndynamics methods are used for simulations of the flow of microscopic and\nnanoscopic films, respectively. Minimization of fluid surface area is used to\nexamine the corresponding equilibrium free energy landscapes. The focus is on\nmotion across patterns containing diverging and converging flow junctions, with\nan eye towards applications to lab-on-a-chip devices. Both open liquid-vapor\nsystems driven by body forces and confined liquid-liquid systems driven by\nboundary motion are considered. As in earlier studies of flow on a linear\nchemical channel, we observe continuous motion of a connected liquid film\nacross repeated copies of the pattern, despite the appearance of pearling\ninstabilities of the interface. Provided that the strength of the driving force\nand the volume of liquid are not too large, the liquid is confined to the\nchemical channels and its motion can be directed by small variations in the\ngeometry of the pattern."
    },
    {
        "anchor": "Inter-filament Attractions Narrow the Length Distribution of Actin\n  Filaments: We show that the exponential length distribution that is typical of actin\nfilaments under physiological conditions dramatically narrows in the presence\nof (i) crosslinker proteins (ii) polyvalent counterions or (iii) depletion\nmediated attractions. A simple theoretical model shows that in equilibrium,\nshort-range attractions enhance the tendency of filaments to align parallel to\neach other, eventually leading to an increase in the average filament length\nand a decrease in the relative width of the distribution of filament lengths.",
        "positive": "Unpacking of a crumpled wire from two-dimensional cavities: The physics of tightly packed structures of a wire and other threadlike\nmaterials confined in cavities has been explored in recent years in connection\nwith crumpled systems and a number of topics ranging from applications to DNA\npacking in viral capsids and surgical interventions with catheter to analogies\nwith the electron gas at finite temperature and with theories of\ntwo-dimensional quantum gravity. When a long piece of wire is injected into\ntwo-dimensional cavities, it bends and originates in the jammed limit a series\nof closed structures that we call loops. In this work we study the extraction\nof a crumpled tightly packed wire from a circular cavity aiming to remove loops\nindividually. The size of each removed loop, the maximum value of the force\nneeded to unpack each loop, and the total length of the extracted wire were\nmeasured and related to an exponential growth and a mean field model consistent\nwith the literature of crumpled wires. Scaling laws for this process are\nreported and the relationship between the processes of packing and unpacking of\nwire is commented upon."
    },
    {
        "anchor": "Collective Behavior Induced Highly Sensitive Magneto-Optic Effect in 2D\n  Inorganic Liquid Crystals: Collective behavior widely exists in nature, ranging from the macroscopic\ncloud of swallows to the microscopic cloud of colloidal particles. The behavior\nof an individual inside the collective is distinctive from its behavior alone,\nas it follows its neighbors. The introduction of such collective behavior in\ntwo-dimensional (2D) materials may offer new possibilities to achieve desired\nbut unattained properties. Here, we report a highly sensitive magneto-optic\neffect and transmissive magneto-coloration via introducing collective behavior\ninto magnetic 2D material dispersions. The increase of ionic strength in the\ndispersion enhances the collective behavior of colloidal particles, giving rise\nto a magneto-optic Cotton-Mouton coefficient up to 2700 T-2m-1 which is the\nhighest value obtained so far, being three orders of magnitude larger than\nother known transparent media. We also reveal linearly dependence of\nmagneto-coloration on the concentration and hydration radius of ions. Such\nlinear dependence and the extremely large Cotton-Mouton coefficient\ncooperatively allow fabrication of giant magneto-birefringent devices for\ncolor-centered visual sensing.",
        "positive": "Dynamics and interactions of active rotors: We consider a simple model of an internally driven self-rotating object; a\nrotor, confined to two dimensions by a thin film of low Reynolds number fluid.\nWe undertake a detailed study of the hydrodynamic interactions between a pair\nof rotors and find that their effect on the resulting dynamics is a combination\nof fast and slow motions. We analyse the slow dynamics using an averaging\nprocedure to take account of the fast degrees of freedom. Analytical results\nare compared with numerical simulations. Hydrodynamic interactions mean that\nwhile isolated rotors do not translate, bringing together a pair of rotors\nleads to motion of their centres. Two rotors spinning in the same sense rotate\nwith an approximately constant angular velocity around each other, while two\nrotors of opposite sense, both translate with the same constant velocity, which\ndepends on the separation of the pair. As a result a pair of counter-rotating\nrotors are a promising model for controlled self-propulsion."
    },
    {
        "anchor": "Ewald sum for hydrodynamic interactions with periodicity in two\n  dimensions: We carry out the Ewald summation for the Rotne-Prager-Yamakawa mobility\ntensor, the Oseen mobility tensor and further variations of both, relevant for\nthe hydrodynamic interactions in colloidal suspensions, where all interacting\nparticles are within a single plane, i.e., adsorbed at a fluid interface or\nother quasi two-dimensional systems. We use the Poisson summation formula for\nsystems periodic in two dimensions and finite in the third dimension in order\nto obtain simple formulae for applications, such as molecular dynamics or\nBrownian dynamics simulations. We show, that for such systems, as soon as noise\nis taken into account, a commonly used approximate three-dimensional Ewald\nsummation leads to a spurious system size dependence, which may considerably\naffect the interpretation of simulation results and will be cured within our\napproach. Additionally, the resulting formulae are found to be computationally\nmuch less expensive than the approximate three-dimensional Ewald summation.",
        "positive": "Stimuli Thresholds for Isomerization-induced Molecular Motions in\n  Azobenzene Containing Materials: We use large scale molecular dynamics simulations of the isomerizations of\nazobenzene molecules diluted inside a simple molecular material, to investigate\nthe effect of a modification of the cis isomer shape on the induced diffusion\nmechanism. To this end we simulate incomplete isomerizations, modifying the\namplitude of the trans to cis isomerization. We find thresholds in the\nevolution of the host molecules mobility with the isomerization amplitude, a\nresult predicted by the cage- breaking mechanism hypothesis (Teboul, V.;\nSaiddine, M.; Nunzi, J.M.; Accary, J.B. J. Chem. Phys. 2011, 134, 114517) and\nby the gradient pressure mechanism theory (Barrett, C.J.; Rochon, P.L.;\nNatansohn, A.L. J. Chem. Phys. 1998, 109, 1505-1516. ). Above the threshold the\ndiffusion then increases linearly with the variation of the chromophore size\ninduced by the isomerization."
    },
    {
        "anchor": "Landau theory for helical nematic phases: We propose Landau phenomenology for describing the phase transition from the\nconventional nematic into the conical helical orientationally non-uniform\nstructure recently identified in liquid crystals formed by \"banana\"-shaped\nmolecules. The mean field predictions are mostly in agreement with experimental\ndata. Based on the analogy with de Gennes model, we argue that fluctuations of\nthe order parameter turn the transition to the first order phase transition\nrather than continuous one predicted by the mean-field theory. This conclusion\nis in agreement with experimental observations. We discuss the new Goldstone\nmode to be observed in the low-temperature phase.",
        "positive": "A Model for Bone Strength and Osteoporotic Fractures: Inner porous regions play a critical role in the load bearing capability of\nlarge bones.We show that an extension of disordered elastic networks [Chung et.\nal., Phys. Rev. B, {\\bf 54}, 15094 (1996)] exhibits analogs of several known\nmechanical features of bone. The \"stress-backbones\" and histograms of stress\ndistributions for healthy and weak networks are shown to be qualitatively\ndifferent. A hereto untested relationship between bone density and bone\nstrength is presented."
    },
    {
        "anchor": "Thermal Stabilities of Two-Dimensional Ball-Stick Polygons: A Critical\n  Edge Number: Phase behaviors of two-dimensional (2D) systems locate as a fundamental topic\nin condensed matter and statistical physics. Although hard polygons and\ninteractive point-like particles are well studied, the phase behaviors of more\nrealistic molecular systems containing intermolecular interaction and molecular\nshape remain elusive. Here we investigate by molecular dynamics simulation\nthermal stabilities of 2D ball-stick polygons, serving as simplified models for\nmolecular systems. Below the melting temperature $T_{m}$, we identify a\ncritical edge number $n_{c}$, at which a waving superlattice structure emerges;\nwhen n < $n_{c}$,the triangular system stabilizes at a spin-ice-like glassy\nstate; when n > $n_{c}$,the polygons stabilize at crystalline states, and\n$T_{m}$ is higher for polygons with more edges at higher pressures but exhibits\na crossover for hexagon and octagon at low pressures. A theoretical framework\nconsidering the competition between entropy and enthalpy is proposed to provide\na comprehensive understanding of our results, which is anticipated to\nfacilitate the design of 2D materials.",
        "positive": "The 'Cheerios effect': Objects that float at the interface between a liquid and a gas interact\nbecause of interfacial deformation and the effect of gravity. We highlight the\ncrucial role of buoyancy in this interaction, which, for small particles,\nprevails over the capillary suction that is often assumed to be the dominant\neffect. We emphasize this point using a simple classroom demonstration, and\nthen derive the physical conditions leading to mutual attraction or repulsion.\nWe also quantify the force of interaction in some particular instances and\npresent a simple dynamical model of this interaction. The results obtained from\nthis model are then validated by comparison to experimental results for the\nmutual attraction of two identical spherical particles. We conclude by looking\nat some of the applications of the effect that can be found in the natural and\nmanmade worlds."
    },
    {
        "anchor": "Mechanical signaling cascades: Mechanical computing has seen resurgent interest recently owing to the\npotential to embed sensing and computation into new classes of programmable\nmetamaterials. To realize this, however, one must push signals from one part of\na device to another, and do so in a way that can be reset robustly. We\ninvestigate the propagation of signals in a bistable mechanical cascade uphill\nin energy. By identifying a penetration length for perturbations, we show that\nsignals can propagate uphill for finite distances and map out parameters for\nthis to occur. Experiments on soft elastomers corroborate our results.",
        "positive": "Are polymer melts \"ideal\"?: It is commonly accepted that in concentrated solutions or melts\nhigh-molecular weight polymers display random-walk conformational properties\nwithout long-range correlations between subsequent bonds. This absence of\nmemory means, for instance, that the bond-bond correlation function, $P(s)$, of\ntwo bonds separated by $s$ monomers along the chain should exponentially decay\nwith $s$. Presenting numerical results and theoretical arguments for both\nmonodisperse chains and self-assembled (essentially Flory size-distributed)\nequilibrium polymers we demonstrate that some long-range correlations remain\ndue to self-interactions of the chains caused by the chain connectivity and the\nincompressibility of the melt. Suggesting a profound analogy with the\nwell-known long-range velocity correlations in liquids we find, for instance,\n$P(s)$ to decay algebraically as $s^{-3/2}$. Our study suggests a precise\nmethod for obtaining the statistical segment length \\bstar in a computer\nexperiment."
    },
    {
        "anchor": "Physical limits on computation by assemblies of allosteric proteins: Assemblies of allosteric proteins, nano-scale Brownian computers, are the\nprinciple information processing devices in biology. The troponin C-troponin I\n(TnC-TnI) complex, the Ca$^{2+}$-sensitive regulatory switch of the heart, is a\nparadigm for Brownian computation. TnC and TnI specialize in sensing (reading)\nand reporting (writing) tasks of computation. We have examined this complex\nusing a newly developed phenomenological model of allostery.\nNearest-neighbor-limited interactions among members of the assembly place\npreviously unrecognized constrains the topology of the system's free energy\nlandscape and generate degenerate transition probabilities. As a result,\nsignaling fidelity and deactivation kinetics can not be simultaneously\noptimized. This trade-off places an upper limit on the rate of information\nprocessing by assemblies of allosteric proteins that couple to a single ligand\nchemical bath.",
        "positive": "Impact of physical-chemistry on the film thinning in surface bubbles: In this paper, we investigate the thinning dynamics of evaporating\nsurfactant-stabilised surface bubbles by considering the role of the\nphysical-chemistry of solutions used in the liquid bath. We study the impact of\nthe surfactant concentration below and above the cmc (critical micelle\nconcentration) and the role of ambient humidity. First, in a humidity-saturated\natmosphere, we show that if the initial thickness depends on the surfactant\nconcentration and is limited by the surface elasticity, the drainage dynamics\nare very well described from the capillary and gravity contributions. These\ndynamics are independent of the surfactant concentration. In a second part, our\nstudy reveals that the physical-chemistry impacts the thinning dynamics through\nevaporation. We include in the model the additional contribution due to\nevaporation, which shows a good description of the experimental data below the\ncmc. Above the cmc, although this model is unsatisfactory at short times, the\ndynamics at long times is correctly rendered and we establish that the increase\nof the surfactant concentration decreases the impact of evaporation. Finally,\nthe addition of a hygroscopic compound, glycerol, can be also rationalized by\nour model. We demonstrate that glycerol decreases the bubble thinning rate at\nambient humidity, thus increasing their stability."
    },
    {
        "anchor": "Bending Frustration of Lipid-Water Mesophases Based on Cubic Minimal\n  Surfaces: Inverse bicontinuous cubic phases are ubiquitous in lipid-water mixtures and\nconsist of a lipid bilayer forming a cubic minimal surface, thereby dividing\nspace into two cubic networks of water channels. For small hydrocarbon chain\nlengths, the monolayers can be modeled as parallel surfaces to a minimal\nmidsurface. The bending energy of the cubic phases is determined by the\ndistribution of Gaussian curvature over the minimal midsurfaces which we\ncalculate for seven different structures (G, D, P, I-WP, C(P), S and F-RD). We\nshow that the free-energy densities of the structures G, D and P are\nconsiderably lower than those of the other investigated structures due to their\nnarrow distribution of Gaussian curvature. The Bonnet transformation between G,\nD, and P implies that these phases coexist along a triple line, which also\nincludes an excess water phase. Our model includes thermal membrane\nundulations. Our qualitative predictions remain unchanged when higher order\nterms in the curvature energy are included. Calculated phase diagrams agree\nwell with the experimental results for 2:1 lauric acid/dilauroyl\nphosphatidylcholine and water.",
        "positive": "Multiscale Model of Clogging in Microfluidic Devices with Grid-Like\n  Geometries: We propose a coarse-grained theoretical model to capture the aging of\nmicrofluidic devices under different conditions including constant applied flow\nrate and constant applied pressure gradient. Microfluidic devices that sort\ncells by their deformability hold significant promise for medical applications.\nHowever, clogging in these microfluidic systems causes their properties to\nchange over time and potentially limits their reliability. We compare the\nresults of the coarse-grained model to those of stochastic simulations and to\nexisting theoretical studies. Lastly, we apply the model to experimental data\non the clogging of sickle red blood cells and discuss its wider applicability."
    },
    {
        "anchor": "Dipolar depletion effect on the differential capacitance of carbon based\n  materials: The remarkably low experimental values of the capacitance data of carbon\nbased materials in contact with water solvent needs to be explained from a\nmicroscopic theory in order to optimize the efficiency of these materials. We\nshow that this experimental result can be explained by the dielectric screening\ndeficiency of the electrostatic potential, which in turn results from the\ninterfacial solvent depletion effect driven by image dipole interactions. We\nshow this by deriving from the microscopic system Hamiltonian a non-mean-field\ndipolar Poisson-Boltzmann equation. This can account for the interaction of\nsolvent molecules with their electrostatic image resulting from the dielectric\ndiscontinuity between the solvent medium and the substrate. The predictions of\nthe extended dipolar Poisson-Boltzmann equation for the differential\ncapacitance are compared with experimental data and good agreement is found\nwithout any fitting parameters.",
        "positive": "Ratchet transport for a chain of interacting charged particles: We study analytically and numerically the overdamped, deterministic dynamics\nof a chain of {\\it charged}, interacting particles driven by a longitudinal\nalternating electric field and additionally interacting with a smooth ratchet\npotential. We derive the equations of motion, analyze the general properties of\ntheir solutions and find the drift criterion for chain motion. For ratchet\npotentials of the form of a double-sine and a phase-modulated sine it is\ndemonstrated that both, a so-called integer and fractional transport of the\nchain can occur. Explicit results for the directed chain transport for these\ntwo classes of ratchet potentials are presented."
    },
    {
        "anchor": "Shear strength of wet granular materials: macroscopic cohesion and\n  effective stress: Rheometric measurements on assemblies of wet polystyrene bead assemblies, in\nsteady uniform quasistatic shear flow, for varying liquid content within the\nsmall saturation (pendular) range of isolated liquid bridges, are supplemented\nwith a systematic study by discrete numerical simulations. Numerical results\nand experimental ones agree quantitatively is the intergranular friction\ncoefficient is set to 0.09, suitable for the dry material. Shear resistance and\nsolid fraction are recorded as functions of the reduced pressure p, comparing\nnormal stress to capillary bridge tensile strength. The Mohr-Coulomb relation\nwith p-independent cohesion c applies for p above 2. The assumption that\ncontact force contributions to stress act as effective stresses predicts shear\nstrength quite well throughout the numerically investigated range of\nparameters.. A generalized Mohr-Coulomb cohesion c is defined, which relates to\nthe dry material internal friction, coordination numbers and capillary force\nnetwork anisotropy. The Rumpf formula approximation, ignoring capillary shear\nstress is correct for the larger saturation range within the pendular regime,\nbut fails to describe its decrease for small liquid contents.",
        "positive": "A particulate basis for a lattice-gas model of amphiphilic fluids: We show that the flux-field expansion derived by Boghosian and Coveney for\nthe Rothman-Keller immiscible fluid model can be derived in a simpler and more\ngeneral way in terms of the completely symmetric tensor kernels introduced by\nthose authors. Using this generalised flux-field expansion we show that the\nmore complex amphiphilic model of Boghosian Coveney and Emerton can also be\nderived from an underlying model of particle interactions. The consequences of\nthis derivation are discussed in the context of previous equilibrium Ising-like\nlattice models and other non-equilibrium mesoscale models."
    },
    {
        "anchor": "Supplementary material to: Finite-size effects in the interfacial\n  stiffness of rough elastic contacts: In this supplementary materials section, we provide (i) additional\ninformation on the numerical simulations of the main work, (ii) the derivation\nof all prefactors in the analytical theory, and (iii) unpublished experiments\nof the contact stiffness of a polymer pressed against a rough substrate.",
        "positive": "Evolution of shear zones in granular packings under pressure: Stress transmission in realistic granular media often occurs under external\nload and in the presence of boundary slip. We investigate shear localization in\na split-bottom Couette cell with smooth walls subject to a confining pressure\nexperimentally and by means of numerical simulations. We demonstrate how the\ncharacteristics of the shear zone, such as its center position and width,\nevolve as the confining pressure and wall slip modify the local effective\nfriction coefficient of the material. For increasing applied pressure, the\nshear zone evolves toward the center of the cylinder and grows wider and the\nangular velocity reduces compared to the driving rate of the bottom disk.\nMoreover, the presence of slip promotes the transition from open shear zones at\nthe top surface to closed shear zones inside the bulk. We also systematically\nvary the ratio of the effective friction near the bottom plate and in the bulk\nin simulations and observe the resulting impact on the surface flow profile.\nBesides the boundary conditions and external load, material properties such as\ngrain size are also known to influence the effective friction coefficient.\nHowever, our numerical results reveal that the center position and width of the\nshear zone are insignificantly affected by the choice of the grain size as far\nas it remains small compared to the radius of the rotating bottom disk."
    },
    {
        "anchor": "Dynamics in poly(propylene glycol) and silica oxide nanoparticles\n  composite glassforming system: Results of broadband dielectric spectroscopy and rheological studies of\npoly(propylene glycol) + SiO${_2}$ nanocomposites are presented. They show that\nthe dynamics in high-concentrated composite is determined by confinement and\nadsorption effects, resulting from interactions of confined polymers correspond\nwith the host system at the interface between PPG and solid nanoparticles. The\nevolution of relaxation times follows the clear Vogel-Fulcher-Tammann pattern,\nwhat is proved by the supplementary activation energy temperature index\nanalysis. The strong influence of nanoparticles on the transitional dynamics\nand the fragility in the ultraviscous domain was noted.",
        "positive": "The influence of the liquid slab thickness on the planar vapor-liquid\n  interfacial tension: One of the long standing challenges in molecular simulation is the\ndescription of interfaces. On the molecular length scale, finite size effects\nsignificantly influence the properties of the interface such as its interfacial\ntension, which can be reliably investigated by molecular dynamics simulation of\nplanar vapor-liquid interfaces. For the Lennard-Jones fluid, finite size\neffects are examined here by varying the thickness of the liquid slab. It is\nfound that the surface tension and density in the center of the liquid region\ndecreases significantly for thin slabs. The influence of the slab thickness on\nboth the liquid density and the surface tension is found to scale with 1/S^3 in\nterms of the slab thickness S, and a linear correlation between both effects is\nobtained. The results corroborate the analysis of Malijevsk\\'y and Jackson, J.\nPhys.: Cond. Mat. 24: 464121 (2012), who recently detected an analogous effect\nfor the surface tension of liquid nanodroplets."
    },
    {
        "anchor": "Long-range interactions & parallel scalability in molecular simulations: Typical biomolecular systems such as cellular membranes, DNA, and protein\ncomplexes are highly charged. Thus, efficient and accurate treatment of\nelectrostatic interactions is of great importance in computational modelling of\nsuch systems. We have employed the GROMACS simulation package to perform\nextensive benchmarking of different commonly used electrostatic schemes on a\nrange of computer architectures (Pentium-4, IBM Power 4, and Apple/IBM G5) for\nsingle processor and parallel performance up to 8 nodes - we have also tested\nthe scalability on four different networks, namely Infiniband, GigaBit\nEthernet, Fast Ethernet, and nearly uniform memory architecture, i.e.,\ncommunication between CPUs is possible by directly reading from or writing to\nother CPUs' local memory. It turns out that the particle-mesh Ewald method\n(PME) performs surprisingly well and offers competitive performance unless\nparallel runs on PC hardware with older network infrastructure are needed.\nLipid bilayers of sizes 128, 512 and 2048 lipid molecules were used as the test\nsystems representing typical cases encountered in biomolecular simulations. Our\nresults enable an accurate prediction of computational speed on most current\ncomputing systems, both for serial and parallel runs. These results should be\nhelpful in, for example, choosing the most suitable configuration for a small\ndepartmental computer cluster.",
        "positive": "Topological Phase Transition in a Quasi Two Dimensional Coulomb Gas: A system with equal number of positive and negative charges confined in a box\nwith a small but finite thickness is modeled as a function of temperature using\nmesoscale numerical simulations, for various values of the charges. The Coulomb\ninteraction is used in its three-dimensional form, U(r) ~ 1/r. A topological\nphase transition is found in this quasi 2d system. The translational order\nparameter, spatial correlation function, specific heat, and electric current\nshow qualitatively different trends below and above a critical temperature. We\nfind that a 2d logarithmic Coulomb interaction is not essential for the\nappearance of this transition. This work suggests new experimental tests of our\npredictions, as well as novel theoretical approaches to probe quasi 2d\ntopological phase transitions."
    },
    {
        "anchor": "Intrinsic curvature determines the crinkled edges of \"crenellated disks\": Elastic curvature constants determine many structural and functional\nproperties of fluid membranes. Methods to measure the mean curvature modulus\nhave proved to be robust. In contrast, Gaussian curvature is an intrinsic\nproperty of a surface. Thus, measuring the relevant modulus $\\bar{k}$ in fluid\nmembranes remains a challenging task. Inspired from colloidal \"crenellated\ndisks\" observed in a model system composed of hard rods, we propose a concise\nrelation between the two curvature moduli and the parameters associated with\nthe free, crinkled edges. Our approach offers a straightforward way to\ndetermine $\\bar{k}$ of these reconfigurable membranes, where various complex\ntopologies can be nanosculpted. Further, we reveal the structure and stability\nof the \"crenellated disks.\"",
        "positive": "Raoult's law revisited: accurately predicting equilibrium relative\n  humidity points for humidity control experiments: The equilibrium relative humidity values for a number of the most commonly\nused precipitants in biological macromolecule crystallisation have been\nmeasured using a new humidity control device. A simple argument in statistical\nmechanics demonstrates that the saturated vapour pressure of a solvent is\nproportional to its mole fraction in an ideal solution (Raoult's Law). The same\nargument can be extended to the case where solvent and solute molecules are of\ndifferent size."
    },
    {
        "anchor": "Writhing Photons and Berry Phases in Diffusive Wave Scattering: We study theoretically the polarization state of light in multiple scattering\nmedia in the limit of weak gradients in refractive index. Linearly polarized\nphotons are randomly rotated due to the Berry phase associated with the\nscattering path. For circularly polarized light independent speckle patterns\nare found for the two helical states. The statistics of the geometric phase is\nrelated to the writhe distribution of semiflexible polymers such as DNA.",
        "positive": "Pattern formation and phase transition in the collective dynamics of a\n  binary mixture of polar self-propelled particles: The collective behavior of a binary mixture of polar self-propelled particles\n(SPPs) with different motile properties is studied. The binary mixture consists\nof slow-moving SPPs (sSPPs) of fixed velocity $v_s$ and fast-moving SPPs\n(fSPPs) of fixed velocity $v_f$. These SPPs interact via a short-range\ninteraction irrespective of their types. They move following certain position\nand velocity update rules similar to the Vicsek model (VM) under the influence\nof an external noise $\\eta$. The system is studied at different values of $v_f$\nkeeping $v_s=0.01$ constant for a fixed density $\\rho=0.5$. Different\nphase-separated collective patterns that appear in the system over a wide range\nof noise $\\eta$ are characterized. The fSPPs and the sSPPs are found to be\norientationally phase-synchronized at the steady-state. We studied an\norientational order-disorder transition varying the angular noise $\\eta$ and\nidentified the critical noise $\\eta_c$ for different $v_f$. Interestingly, both\nthe species exhibit continuous transition for $v_f<100v_s$, and discontinuous\ntransition for $v_f>100v_s$. A new set of critical exponents is determined for\nthe continuous transitions. However, the binary model is found to be\nnon-universal as the values of the critical exponents depend on the velocity.\nThe effect of interaction radius on the system behavior is also studied."
    },
    {
        "anchor": "Dewetting on porous media with aspiration: We consider a porous solid covered with a water film (or with a drop) in\nsituations where the liquid is pumped in, either spontaneously (if the porous\nmedium is hydrophilic) or mechanically (by an external pump). The dynamics of\ndewetting is then strongly modified. We analyse a few major examples: a)\nhorizontal films, which break at a certain critical thickness, b) the \"modified\nLandau-Levich problem\" where a porous plate moves up from a bath and carries a\nfilm: aspiration towards the plate limits the height H reached by the film, c)\ncertain situation where the hysteresis of contact angles is important.",
        "positive": "Unidirectional laning and migrating cluster crystals in confined\n  self-propelled particle systems: One standard approach to describe the collective behaviour of self-propelled\nparticles is the Vicsek model: point-like self-propelled particles tend to\nalign their migration directions to the ones of their nearer neighbours at each\ntime-step. Here we use a variant of the Vicsek model that includes pairwise\nrepulsive interactions. Confining the system between parallel walls can\nqualitatively change its appearance: a laning state can emerge that is\ndifferent from the ones previously reported. All lanes show on average the same\nmigration direction of the contained particles with a finite separation\ndistance between the lanes. Furthermore, in certain parameter ranges we observe\ncollectively migrating clusters that arrange in an approximately hexagonal way.\nWe suggest that the mechanism behind these regular textures is an overreaction\nin the alignment mechanism. Considering the more realistic scenario of\nnon-point-like particles in the presence of confining surfaces is generally\nimportant for the comparison to experimental systems."
    },
    {
        "anchor": "Phase behavior of hard spheres confined between parallel hard plates:\n  Manipulation of colloidal crystal structures by confinement: We study the phase behavior of hard spheres confined between two parallel\nhard plates using extensive computer simulations. We determine the full\nequilibrium phase diagram for arbitrary densities and plate separations from\none to five hard-sphere diameters using free energy calculations. We find a\nfirst-order fluid-solid transition, which corresponds to either capillary\nfreezing or melting depending on the plate separation. The coexisting solid\nphase consists of crystalline layers with either triangular or square symmetry.\nIncreasing the plate separation, we find a sequence of crystal structures from\nn triangular to (n+1) square to (n+1) triangular, where n is the number of\ncrystal layers, in agreement with experiments on colloids. At high densities,\nthe transition between square to triangular phases are intervened by\nintermediate structures, e.g., prism, buckled, and rhombic phases.",
        "positive": "Fluctuation-dissipation theorem in an aging colloidal glass: We provide a direct experimental test of the Stokes-Einstein relation as a\nspecial case of the fluctuation-dissipation theorem (FDT) in an aging colloidal\nglass. The use of combined active and passive microrheology allows us to\nindependently measure both the correlation and response functions in this\nnon-equilibrium situation. Contrary to previous reports, we find no deviations\nfrom the FDT over several decades in frequency (1 Hz-10 kHz) and for all aging\ntimes. In addition, we find two distinct viscoelastic contributions in the\naging glass, including a nearly elastic response at low frequencies that grows\nduring aging. This is the clearest change in material properties of the system\nwith aging."
    },
    {
        "anchor": "Consequences of Anomalous Diffusion in Disordered Systems Under Cyclic\n  Forcing: We use numerical simulations to study the behavior of 2D frictionless disk\nsystems under cyclic shear as a function of reversal amplitude \\gamma_r. Our\nstudies focus on mean bulk and disk dynamics. These measurements suggest a\ncrossover from a subdiffusive, \\gamma_r dependent regime to a regime where the\ngrain motions are diffusive, with properties dependent only on total shear\nstrain. We discuss model stochastic processes that are consistent with these\nobservations. Finally, we introduce a modified Mean-Squared Displacement (mMSD)\nwhich takes into account the motion of the neighborhood of nearby grains and\nyields new insights into local displacement fluctuations. We find that scaling\nproperties of the displacement distributions are consistent with well studied\nstochastic models of anomalous diffusion and suggest scale-invariant cage\ndynamics.",
        "positive": "Stokes-Einstein relation and excess entropy scaling law in liquid Copper: We report an ab initio study of structural and dynamic properties of liquid\ncopper as a function of temperature. In particular, we have evaluated the\ntemperature dependence of the self-diffusion coefficient from the velocity\nautocorrelation function as well the temperature dependence of the viscosity\nfrom the transverse current correlation function. We show that LDA based\nresults are in close agreement with experimental data for both the\nself-diffusion coefficient and the viscosity over the temperature range\ninvestigated. Our findings are then used to test empirical approaches like the\nStokes-Einstein relation and the excess entropy scaling law widely used in the\nliterature. We show that the Stokes-Einstein relation is valid for the liquid\nphase and that the excess entropy scaling law proposed by Dzugutov is\nlegitimate only if a self-consistent method for determining the packing\nfraction of the hard sphere reference liquid is used within the\nCarnahan-Starling approach to express the excess entropy."
    },
    {
        "anchor": "Miscibility of blends of poly(methyl methacrylate) and oligodiols based\n  on a bisphenol A nucleus and ethylene oxide or propylene oxide branches: Cloud-point curves of blends of poly(methyl methacrylate) (PMMA) with a\nseries of oligodiols based on a bisphenol A nucleus and short branches of\npoly(ethylene oxide) or poly(propylene oxide) (BPA-EO or BPA-PO), and with PEO\nand PPO oligomers, were obtained using a light transmission device.\nExperimental results were fitted with the Flory- Huggins model using an\ninteraction parameter depending on both temperature and composition. For\nPMMA/PEO and PMMA/PPO blends, the miscibility increased when increasing the\nsize of the diol, due to the significant decrease in the entropic and enthalpic\nterms contributing to the interaction parameter. This reflected the decrease in\nthe selfassociation of solvent molecules and in the contribution of terminal OH\ngroups to the mismatching of solubility parameters. For PMMA/BPA-EO blends, a\ndecrease of the entropic contribution to the interaction parameter when\nincreasing the size of the oligodiol was also found. However, the effect was\ncounterbalanced by the opposite contribution of combinatorial terms leading to\ncloud-point curves located in approximately the same temperature range. For\nPMMA/BPA-PO blends, the interaction parameter exhibited a very low value. In\nthis case, the effect of solvent size was much more important on combinatorial\nterms than on the interaction parameter, leading to an increase in miscibility\nwhen decreasing the oligodiol size. For short BPA-PO oligodiols no phase\nseparation was observed. The entropic contribution of the interaction parameter\nexhibited an inverse relationship with the size of the oligodiols, independent\nof the nature of the chains bearing the hydroxyls and the type of OH groups\n(primary or secondary). This indicates that the degree of self-association of\nsolvent molecules through their OH terminal groups, was mainly determined by\ntheir relative sizes.",
        "positive": "Self-Consistent Field Approach for Crosslinked Copolymer Materials: A generalized self-consistent field approach for polymer networks with fixed\ntopology is developed. It is shown that the theory reproduces the localization\nof crosslinks which is characteristic for gels. The theory is then used to\nstudy the order-disorder transition in regular networks of endlinked diblock\ncopolymers. Compared to diblock copolymer melts, the transition is shifted\ntowards lower values of the incompatibility parameter $\\chi$ (the Flory-\nHuggins parameter). Moreover, the transition becomes strongly first order\nalready at the mean-field level. If stress is applied, the transition is\nfurther shifted and finally vanishes in a critical point."
    },
    {
        "anchor": "Ion Density Deviations in Polyelectrolyte Microcapsules: Influence on\n  Biosensors: Polyelectrolyte microcapsules loaded with fluorescent dyes have been proposed\nas biosensors to monitor local pH and ionic strength for diagnostic purposes.\nIn the case of charged microcapsules, however, the local electric field can\ncause deviations of ion densities inside the cavities, potentially resulting in\nmisdiagnosis of some diseases. Using nonlinear Poisson-Boltzmann theory, we\nsystematically investigate these deviations induced by charged microcapsules.\nOur results show that the microcapsule charge density, as well as the capsule\nand salt concentrations, contribute to deviations of local ion concentrations\nand pH. Our findings are relevant for applications of polyelectrolyte\nmicrocapsules with encapsulated ion-sensitive dyes as biosensors.",
        "positive": "Dynamical density functional theory for the dewetting of evaporating\n  thin films of nanoparticle suspensions exhibiting pattern formation: Recent experiments have shown that the striking structure formation in\ndewetting films of evaporating colloidal nanoparticle suspensions occurs in an\nultrathin `postcursor' layer that is left behind by a mesoscopic dewetting\nfront. Various phase change and transport processes occur in the postcursor\nlayer, that may lead to nanoparticle deposits in the form of labyrinthine,\nnetwork or strongly branched `finger' structures. We develop a versatile\ndynamical density functional theory to model this system which captures all\nthese structures and may be employed to investigate the influence of\nevaporation/condensation, nanoparticle transport and solute transport in a\ndifferentiated way. We highlight, in particular, the influence of the subtle\ninterplay of decomposition in the layer and contact line motion on the observed\nparticle-induced transverse instability of the dewetting front."
    },
    {
        "anchor": "Towards frustration of freezing transition in a binary hard-disk mixture: The freezing mechanism, recently suggested for a monodisperse hard-disk fluid\n[Huerta et al., Phys. Rev. E, 2006, 74, 061106] is extended here to an\nequimolar binary hard-disk mixtures. We are showing that for diameter ratios,\nsmaller than 1.15 the global orientational order parameter of the binary\nmixture behaves like in the case of a monodisperse fluid. Namely, by increasing\nthe disk number density there is a tendency to form a crystalline-like phase.\nHowever, for diameter ratios larger than 1.15 the binary mixtures behave like a\ndisordered fluid. We use some of the structural and thermodynamic properties to\ncompare and discuss the behavior as a function of diameter ratio and packing\nfraction.",
        "positive": "Stochastic nanoswimmer: a multistate model for enzyme self-propulsion\n  and enhanced diffusion: Several enzymes show enhanced diffusion in the presence of substrate a\nfeature that is explained by postulating that the enzyme in the bound state has\na higher diffusion constant than in the unbound state. In a recent experiment\n[Jee et al. PNAS, 115, E10812 (2018)], it was observed that some of these\nenzymes perform a run-and-tumble motion, where the self-propulsion velocities\ncan be of the order of mm/s. Theoretical models of nanoscale swimmers have not\nbeen able to explain the high self-propulsion speeds measured in experiments.\nHere we model the enzyme as a dimer with fluctuating mobility. We show that\neven a dimer can perform a run-and-tumble motion when the dimer switches\nbetween states of different mobility in the enzymatic cycle. Within a\nthree-state enzymatic cycle, we investigate the conditions under which\nself-propulsion speeds consistent with experiments can be obtained."
    },
    {
        "anchor": "The Individual and Collective Effects of Exact Exchange and Dispersion\n  Interactions on the Ab Initio Structure of Liquid Water: In this work, we report the results of a series of density functional theory\n(DFT) based ab initio molecular dynamics (AIMD) simulations of ambient liquid\nwater using a hierarchy of exchange-correlation (XC) functionals to investigate\nthe individual and collective effects of exact exchange (Exx), via the PBE0\nhybrid functional, non-local vdW/dispersion interactions, via a fully\nself-consistent density-dependent dispersion correction, and approximate\nnuclear quantum effects (aNQE), via a 30 K increase in the simulation\ntemperature, on the microscopic structure of liquid water. Based on these AIMD\nsimulations, we found that the collective inclusion of Exx, vdW, and aNQE as\nresulting from a large-scale AIMD simulation of (H$_2$O)$_{128}$ at the\nPBE0+vdW level of theory, significantly softens the structure of ambient liquid\nwater and yields an oxygen-oxygen structure factor, $S_{\\rm OO}(Q)$, and\ncorresponding oxygen-oxygen radial distribution function, $g_{\\rm OO}(r)$, that\nare now in quantitative agreement with the best available experimental data.\nThis level of agreement between simulation and experiment as demonstrated\nherein originates from an increase in the relative population of water\nmolecules in the interstitial region between the first and second coordination\nshells, a collective reorganization in the liquid phase which is facilitated by\na weakening of the hydrogen bond strength by the use of the PBE0 hybrid XC\nfunctional, coupled with a relative stabilization of the resultant disordered\nliquid water configurations by the inclusion of non-local vdW/dispersion\ninteractions.",
        "positive": "Lily-like twist distribution in toroidal nematics: Toroidal nematics are droplets of nematic liquid crystals in the form of a\ncircular torus. When the nematic director is subject to planar degenerate\nboundary conditions, the bend-only director field with vector lines along the\nparallels of all internal torodial shells is an equilibrium solution for all\nvalues of the elastic constants. Local stability analyses have shown that an\ninstability is expected to occur for sufficiently small values of the twist\nelastic constant. It is natural to conjecture that in this regime the global\nequilibrium would be characterized by a maximum twist deflection on the\nboundary of the torus, with a twist distribution over the torus' cross-section\nrepresented by a fennel-like surface. We prove that surprisingly the stable\ntwist distribution is instead represented by a lily-like surface. Thus the\noverall maximum twist deflection falls well within the torus. To cope with the\ncomplexity of the elastic free-energy functional in the fully non-linear\nsetting, we developed an ad hoc deep-learning optimization method, which here\nis also duly validated and documented for it promises to be applicable to other\nsimilar problems, equally intractable analytically."
    },
    {
        "anchor": "Beta relaxation in the shear mechanics of equilibrium viscous liquids:\n  Phenomenology and network modeling of the alpha-beta merging region: The phenomenology of the beta relaxation process in the shear-mechanical\nresponse of glass-forming liquids is summarized and compared to that of the\ndielectric beta process. Furthermore, we discuss how to model the observations\nby means of standard viscoelastic modeling elements. Necessary physical\nrequirements to such a model are outlined, and it is argued that physically\nrelevant models must be additive in the shear compliance of the alpha and beta\nparts. A model based on these considerations is proposed and fitted to data for\nPolyisobutylene 680.",
        "positive": "Effects of image charges, interfacial charge discreteness, and surface\n  roughness on the zeta potential of spherical electric double layers: We investigate the effects of image charges, interfacial charge discreteness,\nand surface roughness on spherical electric double layers in electrolyte\nsolutions with divalent counter-ions in the setting of the primitive model. By\nusing Monte Carlo simulations and the image charge method, the zeta potential\nprofile and the integrated charge distribution function are computed for\nvarying surface charge strengths and salt concentrations. Systematic\ncomparisons were carried out between three distinct models for interfacial\ncharges: 1) SURF1 with uniform surface charges, 2) SURF2 with discrete point\ncharges on the interface, and 3) SURF3 with discrete interfacial charges and\nfinite excluded volume. By comparing the integrated charge distribution\nfunction (ICDF) and potential profile, we argue that the potential at the\ndistance of one ion diameter from the macroion surface is a suitable location\nto define the zeta potential. In SURF2 model, we find that image charge effects\nstrongly enhance charge inversion for monovalent interfacial charges, and\nstrongly suppress charge inversion for multivalent interfacial charges. For\nSURF3, the image charge effect becomes much smaller. Finally, with image\ncharges in action, we find that excluded volumes (in SURF3) suppress charge\ninversion for monovalent interfacial charges and enhance charge inversion for\nmultivalent interfacial charges. Overall, our results demonstrate that all\nthese aspects, i.e., image charges, interfacial charge discreteness, their\nexcluding volumes have significant impacts on the zeta potential, and thus the\nstructure of electric double layers."
    },
    {
        "anchor": "Nonlinear Kinematics of Recursive Origami Inspired by Spidron: Non-periodic folding of periodic crease patterns paves the way to novel\nnonlinear phenomena that cannot be feasible through periodic folding. This\npaper focuses on the non-periodic folding of recursive crease patterns\ngeneralized from Spidron. Although it is known that Spidron has a 1-DOF\nisotropic rigid folding motion, its general kinematics and dependence on the\ncrease pattern remain unclear. Using the kinematics of a single unit cell of\nSpidron and the recursive construction of the folded state of multiple unit\ncells, we consider the folding of Spidron that is not necessarily isotropic. We\nfound that as the number of unit cells increases, the non-periodic folding is\nrestricted and the isotropic folding becomes dominant. Then, we analyze the\nthree kinds of isotropic folding modes by constructing 1-dimensional dynamical\nsystems governing each of them. We show that the dynamical system can possess\ndifferent recursive natures depending on folding modes even in an identical\ncrease pattern. Furthermore, we show their novel nonlinear nature, including\nthe period-doubling cascade leading to the emergence of chaos.",
        "positive": "The non-monotonic shear-thinning flow of two strongly cohesive\n  concentrated suspensions: The behaviour in simple shear of two concentrated and strongly cohesive\nmineral suspensions showing highly non-monotonic flow curves is described. Two\nrheometric test modes were employed, controlled stress and controlled\nshear-rate. In controlled stress mode the materials showed runaway flow above a\nyield stress, which, for one of the suspensions, varied substantially in value\nand seemingly at random from one run to the next, such that the up flow-curve\nappeared to be quite irreproducible. The down-curve was not though, as neither\nwas the curve obtained in controlled rate mode, which turned out to be\ntriple-valued in the region where runaway flow was seen in controlled rising\nstress. For this first suspension, the total stress could be decomposed into\nthree parts to a good approximation: a viscous component proportional to a\nplastic viscosity, a constant isostatic contribution, and a third shear-rate\ndependent contribution associated with the particulate network which decreased\nwith increasing shear-rate raised to the -7/10th power. In the case of the\nsecond suspension, the stress could be decomposed along similar lines, although\nthe strain-rate softening of the solid-phase stress was found to be logarithmic\nand the irreducible isostatic stress was small. The flow curves are discussed\nin the light of recent simulations and they conform to a very simple but\ngeneral rule for non-monotonic behaviour in cohesive suspensions and emulsions,\nnamely that it is caused by strain-rate softening of the solid phase stress."
    },
    {
        "anchor": "Icosahedral packing of polymer-tethered nanospheres and stabilization of\n  the gyroid phase: We present results of molecular simulations that predict the phases formed by\nthe self-assembly of model nanospheres functionalized with a single polymer\n\"tether\", including double gyroid, perforated lamella and crystalline bilayer\nphases. We show that microphase separation of the immiscible tethers and\nnanospheres causes confinement of the nanoparticles, which promotes local\nicosahedral packing that stabilizes the gyroid and perforated lamella phases.\nWe present a new metric for determining the local arrangement of particles\nbased on spherical harmonic \"fingerprints\", which we use to quantify the extent\nof icosahedral ordering.",
        "positive": "On the Afferrante-Carbone theory of ultratough peeling: In an elegant and interesting theory of ultratough peeling of an elastic tape\nfrom a viscoelastic substrate, Afferrante and Carbone (2016) find that, in\ncontrast to the classic elastic Kendall's theory, there are conditions for\nwhich the load for steady state peeling could be arbitrarily large in steady\nstate peeling, at low angles of peeling - what they call \"ultratough\" peeling.\nIt is here shown in fact that this occurs near critical speeds where the\nelastic energy term of Kendall's equation is balanced by the viscoelastic\ndissipation. Surprisingly, this seems to lead to toughness enhancement higher\nthan the limit value observed in a very large crack in a infinite viscoelastic\nbody, possibly even considering a limit on the stress transmitted. Kendall's\nexperiments in turn had considered viscoelastic tapes (rather than substrates),\nand his viscoelastic findinds seem to lead to a much simpler picture. The\nAfferrante-Carbone theory suggests the viscoelastic effect to be an on-off\nmechanism, since for large angles of peeling it is almost insignificant, while\nonly below a certain threshold, this \"ultratough\" peeling seems to appear.\nExperimental and/or numerical verification would be most useful."
    },
    {
        "anchor": "Influence of dispersion medium structure on the physicochemical\n  properties of aging colloidal suspensions investigated using the synthetic\n  clay Laponite: Hypothesis: Aging in colloidal suspensions manifests as a reduction in\nkinetic freedom of the colloids. In aqueous suspensions of charged colloids,\nthe role of inter-particle electrostatics interactions on the aging dynamics is\nwell debated. Despite water being the dispersion medium, the influence of water\nstructure on the physicochemical properties of aging colloids has never been\nconsidered before. Laponite, a model hectorite clay, could be used to evaluate\nthe relative contributions of medium structure and electrostatics in\ndetermining the physicochemical properties of aging colloidal suspensions.\n  Experiments: The structure of the dispersion medium is modified either by\nincorporating uncharged/charged kosmotropic (structure-inducing) or chaotropic\n(structure-disrupting) molecules or by changing suspension temperature. A new\nprotocol, wherein the medium is heated before adding clay particles, is also\nintroduced to evaluate the effects of hydrogen bond disruptions on suspension\naging. Dynamic light scattering, rheological measurements and particle-scale\nimaging are employed to evaluate the physicochemical properties of the\nsuspensions.\n  Findings: A strong influence of medium structure is evident when\ninter-particle electrostatic interactions are weak. Enhancement and disruption\nof hydrogen bonds in the medium are, respectively, strongly correlated with\nacceleration and delay of suspension aging dynamics. The physicochemical\nproperties of charged clay colloidal suspensions are therefore controlled by\naltering hydrogen bonding in the dispersion medium.",
        "positive": "Electrostatic interactions in charged nanoslits within an explicit\n  solvent theory: Within a dipolar Poisson-Boltzmann theory including electrostatic\ncorrelations, we consider the effect of explicit solvent structure on solvent\nand ion partition confined to charged nanopores. We develop a relaxation scheme\nfor the solution of this highly non-linear integro-differential equation for\nthe electrostatic potential. The scheme is an extension of the approach\npreviously introduced for simple planes (S. Buyukdagli and Ralf Blossey, J.\nChem. Phys. 140, 234903 (2014)) to nanoslit geometry. We show that the reduced\ndielectric response of solvent molecules at the membrane walls gives rise to an\nelectric field significantly stronger than the field of the classical\nPoisson-Boltzmann equation. This peculiarity associated with non-local\nelectrostatic interactions results in turn in an interfacial counterion\nadsorption layer absent in continuum theories. The observation of this enhanced\ncounterion affinity in the very close vicinity of the interface may have\nimportant impacts on nanofludic transport through charged nanopores. Our\nresults indicate the quantitative inaccuracy of solvent implicit nanofiltration\ntheories in predicting the ionic selectivity of membrane nanopores."
    },
    {
        "anchor": "Photo-induced bond breaking during phase separation kinetics of block\n  copolymer melts: A dissipative particle dynamics study: Using dissipative particle dynamics (DPD) simulation method, we study the\nphase separation dynamics in block copolymer (BCP) melt in $d=3$, subjected to\nexternal stimuli such as light. An initial homogeneous BCP melt is rapidly\nquenched to a temperature $T < T_c$, where $T_c$ is the critical temperature.\nWe then let the system go through alternate light \"on\" and \"off\" cycles. An\non-cycle breaks the stimuli-sensitive bonds connecting both the blocks A and B\nin BCP melt, and during the off-cycle, broken bonds reconnect. By simulating\nthe effect of light, we isolate scenarios where phase separation begins with\nthe light off (set 1); the cooperative interactions within the system allow it\nto undergo microphase separation. When the phase separation starts with the\nlight on (set 2), the system undergoes macrophase separation due to the bond\nbreaking. Here, we report the role of alternate cycles on domain morphology by\nvarying bond-breaking probability for both the sets 1 and 2, respectively. We\nobserve that the scaling functions depend upon the conditions mentioned above\nthat change the time scale of the evolving morphologies in various cycles.\nHowever, in all the cases, the average domain size respects the power-law\ngrowth: $R(t)\\sim t^{\\phi}$ at late times, here $\\phi$ is the dynamic growth\nexponent. After a short-lived diffusive growth ($\\phi \\sim 1/3$) at early\ntimes, $\\phi$ illustrates a crossover from the viscous hydrodynamic ($\\phi \\sim\n1$) to the inertial hydrodynamic ($\\phi \\sim 2/3$) regimes at late times.",
        "positive": "Running faster together: huge speed up of thermal ratchets due to\n  hydrodynamic coupling: We present simulations that reveal a surprisingly large effect of\nhydrodynamic coupling on the speed of thermal ratchet motors. The model that we\nuse considers particles performing thermal ratchet motion in a hydrodynamic\nsolvent. Using particle-based, mesoscopic simulations that maintain local\nmomentum conservation, we analyze quantitatively how the coupling to the\nsurrounding fluid affects ratchet motion. We find that coupling can increase\nthe mean velocity of the moving particles by almost two orders of magnitude,\nprecisely because ratchet motion has both a diffusive and a deterministic\ncomponent. The resulting coupling also leads to the formation of aggregates at\nlonger times. The correlated motion that we describe increases the efficiency\nof motor-delivered cargo transport and we speculate that the mechanism that we\nhave uncovered may play a key role in speeding up molecular motor-driven\nintracellular transport."
    },
    {
        "anchor": "Collective guiding of acoustically propelled nano- and microparticles\n  for medical applications: One of the most important potential applications of self-propelled nano- and\nmicrodevices is targeted drug delivery. To realize this, biocompatible\nparticles that can be guided collectively towards a target inside a patient's\nbody are required. Acoustically propelled nano- and microparticles constitute a\npromising candidate for such biocompatible, artificial motile particles. The\nmain remaining obstacle to targeted drug delivery by self-propelled nano- and\nmicrodevices is to also achieve a reliable and biocompatible method for guiding\nthem collectively to their target. Here, we propose such a method. As we\nconfirm by computer simulations, it allows for the remote guiding of large\nnumbers of acoustically propelled particles to a prescribed target by combining\na space- and time-dependent acoustic field and a time-dependent magnetic field.\nThe method works without detailed knowledge about the particle positions and\nfor arbitrary initial particle distributions. With these features, it paves the\nway for the future application of self-propelled particles as vehicles for\ntargeted drug delivery in nanomedicine.",
        "positive": "A Novel Method for Sampling Alpha-Helical Protein Backbones: We present a novel technique of sampling the configurations of helical\nproteins. Assuming knowledge of native secondary structure, we employ assembly\nrules gathered from a database of existing structures to enumerate the\ngeometrically possible three-dimensional arrangements of the constituent\nhelices. We produce a library of possible folds for twenty-five helical protein\ncores. In each case, our method finds significant numbers of conformations\nclose to the native structure. In addition we assign coordinates to all atoms\nfor four of the twenty-five proteins and show that this has a small effect on\nthe number of near-native conformations. In the context of database driven\nexhaustive enumeration our method performs extremely well, yielding significant\npercentages of structures (between 0.02% and 82%) within 6 Angstroms of the\nnative structure. The method's speed and efficiency make it a valuable tool for\npredicting protein structure."
    },
    {
        "anchor": "Phase coexistence in a monolayer of active particles induced by\n  Marangoni flows: Thermally or chemically active colloids generate thermodynamic gradients in\nthe solution in which they are immersed and thereby induce hydrodynamic flows\nthat affect their dynamical evolution. Here we study a mean-field model for the\nmany-body dynamics of a monolayer of active particles located at a fluid-fluid\ninterface. In this case, the activity of the particles creates long-ranged\nMarangoni flows due to the response of the interface, which compete with the\ndirect interaction between the particles. For the most interesting case of a\n$r^{-3}$ soft repulsion that models the electrostatic or magnetic interparticle\nforces, we show that an \"onion-like\" density distribution will develop within\nthe monolayer. For a sufficiently large average density, two-dimensional phase\ntransitions (freezing from liquid to hexatic, and melting from solid to\nhexatic) should be observable in a radially stratified structure. Furthermore,\nthe analysis allows us to conclude that, while the activity may be too weak to\nallow direct detection of such induced Marangoni flows, it is relevant as a\ncollective effect in the emergence of the experimentally observable spatial\nstructure of phase coexistences noted above. Finally, the relevance of these\nresults for potential experimental realizations is critically discussed.",
        "positive": "Escape rate of transiently active Brownian particle in one dimension: Activity significantly enhances the escape rate of a Brownian particle over a\npotential barrier. Whereas constant activity has been extensively studied in\nthe past, little is known about the effect of time-dependent activity on the\nescape rate of the particle. In this paper we study the escape problem for a\nBrownian particle that is transiently active; the activity decreases rapidly\nduring the escape process. Using the effective equilibrium approach we\nanalytically calculate the escape rate, under the assumption that the particle\nis either completely passive or fully active when crossing the barrier. We\nperform numerical simulations of the escape process in one dimension and find\ngood agreement with the theoretical predictions."
    },
    {
        "anchor": "Why do Particle Clouds Generate Electric Charges?: Grains in desert sandstorms spontaneously generate strong electrical charges;\nlikewise volcanic dust plumes produce spectacular lightning displays. Charged\nparticle clouds also cause devastating explosions in food, drug and coal\nprocessing industries. Despite the wide-ranging importance of granular charging\nin both nature and industry, even the simplest aspects of its causes remain\nelusive, because it is difficult to understand how inert grains in contact with\nlittle more than other inert grains can generate the large charges observed.\nHere, we present a simple yet predictive explanation for the charging of\ngranular materials in collisional flows. We argue from very basic\nconsiderations that charge transfer can be expected in collisions of identical\ndielectric grains in the presence of an electric field, and we confirm the\nmodel's predictions using discrete-element simulations and a tabletop granular\nexperiment.",
        "positive": "Energy landscapes, structural topologies and rearrangement mechanisms in\n  clusters of dipolar particles: Clusters of spherical particles with isotropic attraction favour compact\nstructures that maximise the number of energetically optimal nearest-neighbour\ninteractions. In contrast, dipolar interactions lead to the formation of chains\nwith a low coordination number. When both isotropic and dipolar interactions\nare present, the competition between them can lead to intricate knot, link and\ncoil structures. Here, we investigate how these structures may self-organise\nand interconvert in clusters bound by the Stockmayer potential (Lennard-Jones\nplus point dipole). We map out the low-lying region of the energy landscape\nusing disconnectivity graphs to follow how it evolves as the strength of the\ndipolar interactions increases. From comprehensive surveys of isomerisation\npathways, we identify a number of rearrangement mechanisms that allow the\ntopology of chain-like structures to interconvert."
    },
    {
        "anchor": "Confinement Induced Polarization effects in Valence and Inner-shell\n  Spectra of Atactic Polystyrene: Vacuum ultraviolet (VUV) transmission spectra show a clear polarization\neffect in pi electronic transition in spin coated atactic polystyrene (aPS)\nfilms of thickness below 4Rg, where Rg (~20.4nm) is the radius of gyration of\nthe polymer. This transition associated with pendant benzene rings in\npolystyrene. The polarization effect clearly indicates pendant benzene ring\nalignment on a macroscopic scale. Study of core electron (1s) transition\nthrough near edge x-ray absorption fine structure (NEXAFS) spectroscopy\nconfirms the ordering and shows that the rings are oriented towards\nout-of-plane direction with a tilt angle ~63 degree with the sample plane,\nwhich is consistent with the observed in-plane (sample surface) VUV\npolarization. These results indicate the transition of a common polymer, like\npolystyrene, inherently disordered in the bulk, to an orientationally ordered\nphase under a certain degree of confinement.",
        "positive": "Diffusion of a Janus nanoparticle in an explicit solvent: A molecular\n  dynamics simulation study: Molecular dynamics simulations are carried out to study the translational and\nrotational diffusion of a single Janus particle immersed in a dense\nLennard-Jones fluid. We consider a spherical particle with two hemispheres of\ndifferent wettability. The analysis of the particle dynamics is based on the\ntime-dependent orientation tensor, particle displacement, as well as the\ntranslational and angular velocity autocorrelation functions. It was found that\nboth translational and rotational diffusion coefficients increase with\ndecreasing surface energy at the nonwetting hemisphere, provided that the\nwettability of the other hemisphere remains unchanged. We also observed that in\ncontrast to homogeneous particles, the nonwetting hemisphere of the Janus\nparticle tends to rotate in the direction of the displacement vector during the\nrotational relaxation time."
    },
    {
        "anchor": "Influence of roughness on the dynamical properties of granular gases: The statistical-physical study of granular matter is essential to understand,\nfrom a fundamental point of view, the many different phenomena emerging in\nthese classical many-body systems. Under rapid-flow conditions, granular\nmaterials exhibit a gas-like behavior, which can be described from the kinetic\ntheory of gases. However, unlike molecular gases, a granular gas dissipates\nenergy upon particle collisions, thus being completely out of equilibrium.\nThen, whereas the simplest model for a molecular gas consists in a collection\nof elastic hard spheres, a granular gas is simply described by inelastic hard\nspheres, which is usually improved by the consideration of surface roughness in\nthe particles. Moreover, a granular gas can be found in free evolution,\nexternally driven, or even immersed in an interstitial fluid. In this work, the\ndescription of the dynamics of granular gases has been carried out with the aim\nof identifying the specific properties emerging from the model by considering\nthe surface roughness of granular particles. For that end, we have used the\nBoltzmann equation, adding in the driven and suspension cases a\nFokker--Planck-like term. The main objectives of this thesis have been the\ntheoretical description of the homogeneous states of the considered models, as\nwell as the study of memory effects emerging from out-of-equilibrium states,\nand, finally, the transport properties and the appearance of instabilities in\nthe hydrodynamic description of a granular gas of inelastic and rough\nparticles. All these kinetic-theory analyses have been supplemented with\ncomputer simulations from Monte Carlo and molecular dynamics algorithms.",
        "positive": "Modeling of effective interactions between ligand coated nanoparticles\n  through symmetry functions: Ligand coated nanoparticles are complex objects consisting of a metallic or\nsemiconductor core with organic ligands grafted on their surface. These organic\nligands provide stability to a nanoparticle suspension. In solutions, the\neffective interactions between such nanoparticles are mediated through a\ncomplex interplay of interactions between the nanoparticle cores, the\nsurrounding ligands and the solvent molecules. While it is possible to compute\nthese interactions using fully atomistic molecular simulations, such\ncomputations are too expensive for studying self-assembly of a large number of\nnanoparticles. The problem can be made tractable by removing the degrees of\nfreedom associated with the ligand chains and solvent molecules and using the\npotentials of mean force (PMF) between nanoparticles. In general, the\nfunctional dependence of the PMFs on the inter-particle distance is unknown and\ncan be quite complex. In this article, we present a method to model the\ntwo-body and three-body potentials of mean force between ligand coated\nnanoparticles through a linear combination of symmetry functions. The method is\nquite general and can be extended to model interactions between different types\nof macromolecules."
    },
    {
        "anchor": "Dynamic self-assembly of microscale rotors and swimmers: Biological systems often involve the self-assembly of basic components into\ncomplex and function- ing structures. Artificial systems that mimic such\nprocesses can provide a well-controlled setting to explore the principles\ninvolved and also synthesize useful micromachines. Our experiments show that\nimmotile, but active, components self-assemble into two types of structure that\nexhibit the fundamental forms of motility: translation and rotation.\nSpecifically, micron-scale metallic rods are designed to induce extensile\nsurface flows in the presence of a chemical fuel; these rods interact with each\nother and pair up to form either a swimmer or a rotor. Such pairs can\ntransition reversibly be- tween these two configurations, leading to kinetics\nreminiscent of bacterial run-and-tumble motion.",
        "positive": "Radius evolution for bubbles with elastic shells: We present an analysis of an extended Rayleigh-Plesset (RP) equation for a\nthree dimensional cell of microorganisms such as bacteria or viruses in some\nliquid, where the cell membrane in bacteria or the envelope (capsid) in viruses\npossess elastic properties. To account for rapid changes in the shape\nconfiguration of such microorganisms, the bubble membrane/envelope must be\nrigid to resist large pressures while being flexible to adapt to growth or\ndecay. Such properties are embedded in the RP equation by including a pressure\nbending term that is proportional to the square of the curvature of the elastic\nwall. Analytical solutions to this extended equation are obtained in terms of\nelliptic functions."
    },
    {
        "anchor": "Linear Viscoelasticity of Dumbbells Interacting via Gaussian Soft-Core\n  Potential: In polymer melts, the interaction between segments are considered to be\nscreened and the ideal Gaussian chain statistics is recovered. The experimental\nfact that linear viscoelasticity of unentangled polymers can be well described\nby the Rouse model is naively considered as due to this screening effect.\nAlthough various theoretical models are based on the screening effect and the\nscreening effect is believed to be reasonable, the screening effect cannot be\nfully justified on a solid theoretical basis. In this work, we study the\nscreening effect by utilizing a simple dumbbell type model. We perform\nsimulations for dumbbell systems in which particles interact via the Gaussian\nsoft-core potential. We show that, if the density of dumbbells is high, the\nGaussian soft-core interaction is actually screened and the static structures\nare well described by the ideal model without Gaussian soft-core interaction.\nWe also show that the relaxation moduli of interacting dumbbell systems\napproximately coincide to those of the non-interacting dumbbell systems. In the\nlow density systems, we observe the deviations from the ideal non-interacting\nsystems. For example, the relaxation moduli become relatively broad. However,\nthe relaxation moduli of such systems can be decomposed into the relaxation\nmodes by the Gaussian soft-core interaction and the bond. The bond relaxation\nmode can be successfully described by a single Maxwell relaxation with\neffective relaxation strength and time. Our results support a naive use of the\nRouse model to analyze unentangled polymer melts.",
        "positive": "Stratification, multivalency and turnover of the active cortical\n  machinery are required for steady active contractile flows at the cell\n  surface: Many cell membrane proteins that bind to actin form dynamic clusters driven\nby contractile flows generated by the actomyosin machinery at the cell cortex.\nRecent evidence suggests that a necessary condition for the generation of these\nprotein clusters on the membrane is the stratified organization of the active\nagents -formin-nucleated actin, myosin-II minifilaments, and ARP2/3-nucleated\nactin mesh -within the cortex. Further, the observation that these clusters\ndynamically remodel, requires that the components of this active machinery\nundergo turnover. Here we develop a coarse-grained agent-based Brownian\ndynamics simulation that incorporates the effects of stratification, binding of\nmyosin minifilaments to multiple actin filaments and their turnover. We show\nthat these three features of the active cortical machinery -stratification,\nmultivalency and turnover -are critical for the realisation of a nonequilibrium\nsteady state characterised by contractile flows and dynamic orientational\npatterning. We show that this nonequilibrium steady state enabled by the above\nfeatures of the cortex, can facilitate multi-particle encounters of membrane\nproteins that profoundly influence the kinetics of bimolecular reactions at the\ncell surface."
    },
    {
        "anchor": "Criticality in sheared, disordered solids. II. Correlations in avalanche\n  dynamics: Disordered solids respond to quasistatic shear with intermittent avalanches\nof plastic activity, an example of the crackling noise observed in many\nnonequilibrium critical systems. The temporal power spectrum of activity within\ndisordered solids consists of three distinct domains: a novel power-law rise\nwith frequency at low frequencies indicating anticorrelation, white-noise at\nintermediate frequencies, and a power-law decay at high frequencies. As the\nstrain rate increases, the white-noise regime shrinks and ultimately disappears\nas the finite strain rate restricts the maximum size of an avalanche. A new\nstrain-rate- and system-size-dependent scaling theory is derived for power\nspectra in both the quasistatic and finite-strain-rate regimes. This theory is\nvalidated using data from overdamped two- and three-dimensional molecular\ndynamics simulations. We identify important exponents in the yielding\ntransition including the dynamic exponent $z$ which relates the size of an\navalanche to its duration, the fractal dimension of avalanches, and the\nexponent characterizing the divergence in correlations with strain rate.\nResults are related to temporal correlations within a single avalanche and\nbetween multiple avalanches.",
        "positive": "Entropic self-assembly of freely rotating polyhedral particles confined\n  to a flat interface: The self-assembly of hard polyhedral particles confined to a flat interface\nis studied using Monte Carlo simulations. The particles are pinned to the\ninterface by restricting their movement in the direction perpendicular to it\nwhile allowing their free rotations. The six different polyhedral shapes\nstudied in this work are selected from a family of truncated cubes defined by a\ntruncation parameter, s, which varies from cubes (s = 0) via cuboctahedra (s =\n0.5) to octahedra (s = 1). Our results suggest that shapes with small values of\ns show square-like behavior whereas shapes with large values of s tend to show\nmore disc-like behavior. At an intermediate value of s = 0.4, the phase\nbehavior of the system shows both square-like and disc-like features. The\nresults are also compared with the phase behavior of 3D bulk polyhedra and of\n2D rounded hard squares. Both comparisons reveal key similarities in the number\nand sequence of mesophases and solid phases observed. These insights on 2D\nentropic self-assembly of polyhedral particles is a first step toward\nunderstanding the self-assembly of particles at fluid-fluid interfaces, which\nis driven by a complex interplay of entropic and enthalpic forces."
    },
    {
        "anchor": "Yield stress and shear-banding in granular suspensions: We study the emergence of a yield stress in dense suspensions of non-Brownian\nparticles, by combining local velocity and concentration measurements using\nMagnetic Resonance Imaging with macroscopic rheometric experiments. We show\nthat the competition between gravity and viscous stresses is at the origin of\nthe development of a yield stress in these systems at relatively low volume\nfractions. Moreover, it is accompanied by a shear banding phenomenon that is\nthe signature of this competition. However, if the system is carefully density\nmatched, no yield stress is encountered until a volume fraction of 62.7 0.3%.",
        "positive": "Anisotropic Stick-Slip Behavior of Aqueous Drops on Lubricated\n  Chemically Heterogeneous Slippery Surfaces: Conventional slippery surfaces show isotropic drop mobility in all\ndirections, but many applications require directional drop motion along a\nparticular path only. In previous studies, researchers used topographic\nsubstrates, together with different external stimuli, to demonstrate\nanisotropic drop motion, which is not very efficient and cost-effective.\nHerein, we report a novel approach to smartly control drop motion on\nlubricating fluid coated chemically heterogeneous surfaces composed of\nalternating hydrophobic and hydrophilic stripes. Upon depositing an aqueous\ndrop on such a surface, the underneath lubricating fluid dewets from the\nhydrophilic regions but remains intact on the hydrophobic ones, providing\nsticky and slippery areas for the drop. This results in remarkable anisotropic\ndrop sliding behavior, from uniform motion along parallel to stripes to\nstick-slip motion along the perpendicular to them. Furthermore, we also\ndemonstrate a phase diagram summarizing different dynamic situations exhibited\nby drops, sticking, or moving in one or both directions."
    },
    {
        "anchor": "Dynamics, Rectification, and Fractionalization for Colloids on Flashing\n  Substrates: We show that a rich variety of dynamic phases can be realized for mono- and\nbidisperse mixtures of interacting colloids under the influence of a symmetric\nflashing periodic substrate. With the addition of dc or ac drives, phase\nlocking, jamming, and new types of ratchet effects occur. In some regimes we\nfind that the addition of a non-ratcheting species increases the velocity of\nthe ratcheting particles. We show that these effects occur due to the\ncollective interactions of the colloids.",
        "positive": "Velocity correlations in dense granular flows observed with internal\n  imaging: We show that the velocity correlations in uniform dense granular flows inside\na silo are similar to the hydrodynamic response of an elastic hard-sphere\nliquid. The measurements are made using a fluorescent refractive index matched\ninterstitial fluid in a regime where the flow is dominated by grains in\nenduring contact and fluctuations scale with the distance traveled, independent\nof flow rate. The velocity autocorrelation function of the grains in the bulk\nshows a negative correlation at short time and slow oscillatory decay to zero\nsimilar to simple liquids. Weak spatial velocity correlations are observed over\nseveral grain diameters. The mean square displacements show an inflection point\nindicative of caging dynamics. The observed correlations are qualitatively\ndifferent at the boundaries."
    },
    {
        "anchor": "Understanding Divergent Thermal Conductivity in Single Polythiophene\n  Chains using Modal Analysis and Sonification: We used molecular dynamics simulations, the Green-Kubo Modal Analysis (GKMA)\nmethod and sonification to study the modal contributions to thermal\nconductivity in individual polythiophene chains. The simulations suggest that\nit is possible to achieve divergent thermal conductivity and the GKMA method\nallowed for exact pinpointing of the modes responsible for the anomalous\nbehavior. The analysis showed that transverse vibrations in the plane of the\naromatic rings at low frequencies ~ 0.05 THz are primarily responsible. Further\ninvestigation showed that the divergence arises from persistent correlation\nbetween the three lowest frequency modes on chains. Sonification of the mode\nheat fluxes revealed regions where the heat flux amplitude yields a somewhat\nsinusoidal envelope with a long period similar to the relaxation time. This\ncharacteristic in the divergent mode heat fluxes gives rise to the overall\nthermal conductivity divergence, which strongly supports earlier hypotheses\nthat attribute the divergence to correlated phonon-phonon\nscattering/interactions.",
        "positive": "Intra-Globular Structures in Multiblock Copolymer Chains from a Monte\n  Carlo Simulation: Multiblock copolymer chains in implicit nonselective solvents are studied by\nMonte Carlo method which employs a parallel tempering algorithm. Chains\nconsisting of 120 $A$ and 120 $B$ monomers, arranged in three distinct\nmicroarchitectures: $(10-10)_{12}$, $(6-6)_{20}$, and $(3-3)_{40}$, collapse to\nglobular states upon cooling, as expected. By varying both the reduced\ntemperature $T^*$ and compatibility between monomers $\\omega$, numerous\nintra-globular structures are obtained: diclusters (handshake, spiral, torus\nwith a core, etc.), triclusters, and $n$-clusters with $n>3$ (lamellar and\nother), which are reminiscent of the block copolymer nanophases for spherically\nconfined geometries. Phase diagrams for various chains in the $(T^*,\n\\omega)$-space are mapped. The structure factor $S(k)$, for a selected\nmicroarchitecture and $\\omega$, is calculated. Since $S(k)$ can be measured in\nscattering experiments, it can be used to relate simulation results to an\nexperiment. Self-assembly in those systems is interpreted in term of\ncompetition between minimization of the interfacial area separating different\ntypes of monomers and minimization of contacts between chain and solvent.\nFinally, the relevance of this model to the protein folding is addressed."
    },
    {
        "anchor": "Signatures of a Concentration Dependent Flory chi Parameter: Swelling\n  and Collapse of Coils and Brushes: The quality of solvents of polymers is often described in terms of the Flory\nchi parameter typically assumed to depend only on the temperature, T. In\ncertain polymer-solvent systems fitting the experimental data enforces the\nreplacement of chi(T) by a concentration dependent chieff. In turn, this\nmodifies the swelling and collapse behavior. These effects are studied, in the\nframework of a mean-field theory, for isolated coils and for planar brushes.\nThe phi dependence of chieff gives rise to three main consequences: (i) Shift\nin the cross-over between Gaussian and self-avoidance regimes; (ii) A\npossibility of first-order collapse transition for isolated flexible coils;\n(iii) The possibility of a first-order phase transition leading to a vertical\nphase separation within the brush. The discussion relates these effects\ndirectly to thermodynamic measurements and does not involve a specific\nmicroscopic model. The implementation for the case of\nPoly(N-isopropylacrylamide) (PNIPAM) is discussed.",
        "positive": "Dissipative particle dynamics for interacting systems: We introduce a dissipative particle dynamics scheme for the dynamics of\nnon-ideal fluids. Given a free-energy density that determines the\nthermodynamics of the system, we derive consistent conservative forces. The use\nof these effective, density dependent forces reduces the local structure as\ncompared to previously proposed models. This is an important feature in\nmesoscopic modeling, since it ensures a realistic length and time scale\nseparation in coarse-grained models. We consider in detail the behavior of a\nvan der Waals fluid and a binary mixture with a miscibility gap. We discuss the\nphysical implications of having a single length scale characterizing the\ninteraction range, in particular for the interfacial properties."
    },
    {
        "anchor": "Microscopic theory for the glass transition in a system without static\n  correlations: We study the orientational dynamics of infinitely thin hard rods of length L,\nwith the centers-of-mass fixed on a simple cubic lattice with lattice constant\na.We approximate the influence of the surrounding rods onto dynamics of a pair\nof rods by introducing an effective rotational diffusion constant D(l),l=L/a.\nWe get D(l) ~ [1-v(l)], where v(l) is given through an integral of a\ntime-dependent torque-torque correlator of an isolated pair of rods. A glass\ntransition occurs at l_c, if v(l_c)=1. We present a variational and a\nnumerically exact evaluation of v(l).Close to l_c the diffusion constant\ndecreases as D(l) ~ (l_c-l)^\\gamma, with \\gamma=1. Our approach predicts a\nglass transition in the absence of any static correlations, in contrast to\npresent form of mode coupling theory.",
        "positive": "Elastic models for the non-Arrhenius viscosity of glass-forming liquids: This paper first reviews the shoving model for the non-Arrhenius viscosity of\nviscous liquids. According to this model the main contribution to the\nactivation energy of a flow event is the energy needed for molecules to shove\naside the surrounding, an energy which is proportional to the instantaneous\nshear modulus of the liquid. Data are presented supporting the model. It is\nshown that the fractional Debye-Stokes-Einstein relation, that quantitatively\nexpresses the frequently observed decoupling of, e.g., conductivity from\nviscous flow, may be understood within the model. The paper goes on to review\nseveral related explanations for the non-Arrhenius viscosity. Most of these are\nalso \"elastic models,\" i.e., they express the viscosity activation energy in\nterms of short-time elastic properties of the liquid. Finally, two new\narguments for elastic models are given, a general solid-state defect argument\nand an Occam's razor type argument."
    },
    {
        "anchor": "Universal symmetry of optimal control at the microscale: Optimal control is an important field in thermodynamics, mathematics and\nengineering which searches for strategies e.g. to move an object to a target\nposition within a given time with minimal energetic effort. Especially for\nmicro- and nanomachines, for which power supply is often limited, knowledge of\noptimal control protocols is crucial for their operation under realistic\nconditions. Here we investigate experimentally and theoretically the optimal\nprotocol for transporting a microscopic colloidal particle with an optical trap\nin such a way that the required work is minimal. The experiments were conducted\nin viscous and viscoelastic media, which represent typical environments for\nsynthetic and biological nanomachines. Despite marked differences between the\nprotocols in both fluids, we find that the optimal transport protocol and the\ncorresponding average particle trajectory always obeys time-reversal symmetry.\nThis symmetry, which surprisingly appears here for a class of processes far\naway from thermal equilibrium, is moreover expected to hold universally for\ne.g. active, granular and long-range correlated media in their linear regimes.\nThe uncovered symmetry provides a rigorous and versatile criterion for optimal\ncontrol which greatly facilitates the search of energy-efficient transport\nstrategies in a wide range of systems.",
        "positive": "Hyperbolic Interfaces: Fluid interfaces, such as soap films, liquid droplets or lipid membranes, are\nknown to give rise to several special geometries, whose complexity and beauty\ncontinue to fascinate us, as observers of the natural world, and challenge us\nas scientists. Here I show that a special class of surfaces of constant\nnegative Gaussian curvature can be obtained in fluid interfaces equipped with\nan orientational ordered phase. These arise in various soft and biological\nmaterials, such as nematic liquid crystals, cytoskeletal assemblies, or hexatic\ncolloidal suspensions. The purely hyperbolic morphology originates from the\ncompetition between surface tension, that reduces the area of the interface at\nthe expense of increasing its Gaussian curvature, and the orientational\nelasticity of the ordered phase, that in turn suffers for the distortion\ninduced by the underlying curvature."
    },
    {
        "anchor": "Lattice model of linear telechelic polymer melts. I. Inclusion of chain\n  semiflexibility in the lattice cluster theory: The lattice cluster theory (LCT) for the thermodynamics of polymer systems\nhas recently been reformulated to treat strongly interacting self-assembling\npolymers composed of fully flexible linear telechelic chains [J. Dudowicz and\nK. F. Freed, J. Chem. Phys. \\textbf{136}, 064902 (2012)]. Here, we further\nextend the LCT for linear telechelic polymer melts to include a description of\nchain semiflexibility, which is treated by introducing a bending energy penalty\nwhenever a pair of consecutive bonds from a single chain lies along orthogonal\ndirections. An analytical expression for the Helmholtz free energy is derived\nfor the model of semiflexible linear telechelic polymer melts. The extension\nprovides a theoretical tool for investigating the influence of chain stiffness\non the thermodynamics of self-assembling telechelic polymers, and for further\nexploring the influence of self-assembly on glass formation in such systems.",
        "positive": "Hydration, Ion Distribution, and Ionic Network Formation in Sulfonated\n  Poly(arylene ether sulfones): We use molecular dynamics simulations to probe hydration, ion spacing, and\ncation-anion interaction in two sulfonated polysulfones with different ion\ndistributions along the polymer backbone. At room temperature, these polymers\nremain in a glassy state even with water contents more than 10%. At the\nequilibrium water uptake, the ions exhibit a similar level of hydration as they\nwould in their saturated aqueous solution. The framework of Manning's limiting\nlaw for counterion condensation is used to examine ionic interactions in the\nsimulated polysulfones. The dielectric constant that the ions experience can be\nwell approximated by a volume-weighted average of the dielectric constants of\nthe polymer backbone and water. Our results show that a reasonable estimate of\nthe average inter-ion distance, b, is obtained by using the distance where the\nsulfonate-sulfonate coordination number reaches 1. The spacing of the sulfonate\nions along the polysulfone backbone plays a role in determining their spatial\ndistribution inside the hydrated polymer. As a result, the value of b is\nslightly larger for polymers where the sulfonate ions are more evenly spaced\nalong the backbone, which is consistent with experimental evidence. The\nsimulations reveal that the sulfonate ions and sodium counterions form\nfibrillar aggregates at water contents below the equilibrium water uptake. Such\nextensive ionic aggregates are expected to facilitate ion transport in\nsulfonated polysulfone membranes, without the need for long-range chain motion\nas in the case of traditional rubbery ionic polymers. Our estimates for the\ndielectric constant and b are used in conjunction with Manning's theory to\nestimate the fraction of counterions condensed to the fixed ions. The\nprediction of Manning's theory agrees well with the simulation result."
    },
    {
        "anchor": "Bragg spectroscopy of the multi-branch Bogoliubov spectrum of elongated\n  Bose-Einstein condensates: We measure the response of an elongated Bose-Einstein condensate to a\ntwo-photon Bragg pulse. If the duration of the pulse is long, the total\nmomentum transferred to the condensate exhibits a nontrivial behavior which\nreflects the structure of the underlying Bogoliubov spectrum. It is thus\npossible to perform a spectroscopic analysis in which axial phonons with\ndifferent number of radial nodes are resolved. The local density approximation\nis shown to fail in this regime, while the observed data agrees well with the\nresults of simulations based on the numerical solution of the Gross-Pitaevskii\nequation.",
        "positive": "Depletion forces on circular and elliptical obstacles induced by active\n  matter: Depletion forces exerted by self-propelled particles on circular and\nelliptical passive objects are studied using numerical simulations. We show\nthat a bath of active particles can induce repulsive and attractive forces\nwhich are sensitive to the shape and orientation of the passive objects (either\nhorizontal or vertical ellipses). The resultant force on the passive objects\ndue to the active particles is studied as a function of the shape and\norientation of the passive objects, magnitude of the angular noise, distance\nbetween the passive objects. By increasing the distance between obstacles the\nmagnitude of the repulsive depletion force increases, as long as such a\ndistance is less than one active particle diameter. For longer distances, the\nmagnitude of the force always decrease with increasing distance. We also found\nthat attractive forces may arise for vertical ellipses at high enough area\nfraction."
    },
    {
        "anchor": "Analytical classical density functionals from an equation learning\n  network: We explore the feasibility of using machine learning methods to obtain an\nanalytic form of the classical free energy functional for two model fluids,\nhard rods and Lennard--Jones, in one dimension . The Equation Learning Network\nproposed in Ref. 1 is suitably modified to construct free energy densities\nwhich are functions of a set of weighted densities and which are built from a\nsmall number of basis functions with flexible combination rules. This setup\nconsiderably enlarges the functional space used in the machine learning\noptimization as compared to previous work 2 where the functional is limited to\na simple polynomial form. As a result, we find a good approximation for the\nexact hard rod functional and its direct correlation function. For the\nLennard--Jones fluid, we let the network learn (i) the full excess free energy\nfunctional and (ii) the excess free energy functional related to interparticle\nattractions. Both functionals show a good agreement with simulated density\nprofiles for thermodynamic parameters inside and outside the training region.",
        "positive": "Droplet tilings in precessive fields: hysteresis, elastic defects, and\n  annealing: Two-component Marangoni contracted droplets can be arranged into arbitrary\ntwo-dimensional tiling patterns where they display rich dynamics due to vapor\nmediated long-range interactions. Recent work has characterized the centered\nhexagonal honeycomb lattice, showing it to be a highly frustrated system with\nmany metastable states and relaxation occurring over multiple timescales\n[Molina et al., PNAS, 2021, 18, 34]. Here, we study this system under the\ninfluence of a rotating gravitational field. High amplitudes are able to\ncompletely disrupt droplet-droplet interactions, making it possible to identify\na transition between field-dominated to interaction-dominated regimes. The\nsystem displays complex hysteresis behavior, the details of which are connected\nto the emergence of linear mesoscale structures. These mesoscale features\ndisplay an elasticity that is governed by the balance between gravity and\nlong-ranged vapor-mediated attractions. We find that disorder plays an\nimportant role in determining the dynamics of these features. Finally, we\ndemonstrate the ability to anneal the system by progressively reducing the\nfield amplitude, a process that reduces configurational energy compared to a\nrapid quench. The ability to manipulate vapor-mediated interactions in\ndeliberately designed droplet tilings provides a novel platform for table-top\nexplorations of multi-body interactions."
    },
    {
        "anchor": "Morphological transitions of block copolymer micelles: implications for\n  isoporous membrane ordering: Isoporous membranes made from diblock copolymers have numerous applications,\nincluding water treatment and protein separation, and are successfully produced\nat a laboratory scale under controlled conditions. However, achieving optimal\nconditions for membrane preparation remains a challenge due to the complexity\nof the involved phenomena. Experimental studies have shown that the\nself-assembly of block copolymers in solution significantly affects the final\nmembrane structure. Despite extensive research, understanding the multiscale\nphenomena leading to the characteristic morphology is still elusive. We address\nthis gap by using mesoscale computational simulations to investigate the\nself-assembly of block copolymers in selective solvents, consistent with\nisoporous membrane preparation. We focus on the interplay between entropic and\nenthalpic interactions and their effects on the morphology of the micellar\naggregates in solution. Our computational results are consistent with\nexperimental evidence, revealing a morphological transition of the aggregates\nas the polymer concentration and solvent affinity change. We propose different\nphase parameters to characterize the emergence of monodisperse-spherical\nmicelles in solution and describe the order of crew-cut micelles using a\nrigid-sphere approximation. Our study provides valuable insights into the\nself-assembly of diblock copolymers to optimize the preparation of isoporous\nmembranes.",
        "positive": "Bistable colloidal orientation near a charged surface: Anisotropic particles oriented in a specific direction can act as artificial\natoms and molecules, and their controlled assembly can result in a wide variety\nof ordered structures. Towards this, we demonstrate the orientation transitions\nof uncharged peanut-shaped polystyrene colloids, suspended in a non-ionic\naprotic polar solvent, near a flat surface whose potential is static or\ntime-varying. The charged surface is coated with an insulating dielectric layer\nto suppress electric currents. The transition between several orientation\nstates such as random, normal or parallel orientation with respect to the\nsurface, is examined for two different colloid sizes at low-frequency ($\\sim\n10-350$ kHz) or static fields, and at small electric potentials. In\ntime-varying (AC) field, a detailed phase diagram in the potential-frequency\nplane indicating the transition between particles parallel or normal to the\nsurface is reported. We next present the first study of orientation switching\nin static (DC) fields, where no electro-osmotic or other flow is present. A\nreversible change between the two colloidal states is explained by a theory\nshowing that the sum of electrostatic and gravitational energies of the colloid\nis bistable. The number of colloids in each of the two states depends on the\nexternal potential, particle and solvent permittivities, particle aspect ratio,\nand distance from the electrode."
    },
    {
        "anchor": "Nanodrop impact on solid surfaces: The impact of nanometer sized drops on solid surfaces is studied using\nmolecular dynamics simulations. Equilibrated floating drops consisting of short\nchains of Lennard-Jones liquids with adjustable volatility are directed\nnormally onto an atomistic solid surface where they are observed to bounce,\nstick, splash or disintegrate, depending on the initial velocity and the nature\nof the materials involved. Drops impacting at low velocity bounce from\nnon-wetting surfaces but stick and subsequently spread slowly on wetting\nsurfaces. Higher velocity impacts produce an prompt splash followed by\ndisintegration of the drop, while at still higher velocity drops disintegrate\nimmediately. The disintegration can be understood as either a loss of coherence\nof the liquid or as the result of a local temperature exceeding the\nliquid-vapor coexistence value. In contrast to macroscopic drops, the presence\nof vapor outside the drop does not effect the behavior in any significant way.\nNonetheless, the transition between the splashing and bouncing/sticking regimes\noccur at Reynolds and Weber numbers similar to those found for larger drops.",
        "positive": "Ring DNA confers enhanced bulk elasticity and restricted macromolecular\n  diffusion in DNA-dextran blends: Polymer architecture plays critical roles in both bulk rheological properties\nand microscale macromolecular dynamics in entangled polymer solutions and\ncomposites. Ring polymers, in particular, have been the topic of much debate\ndue to the inability of the celebrated reptation model to capture their\nobserved dynamics. Macrorheology and differential dynamic microscopy (DDM) are\npowerful methods to determine entangled polymer dynamics across scales, yet\nthey typically require different samples under different conditions, preventing\ndirect coupling of bulk rheological properties to the underlying macromolecular\ndynamics. Here, we perform macrorheology on composites of highly-overlapping\nDNA and dextran polymers, focusing on the role of DNA topology (rings versus\nlinear chains) as well as the relative volume fractions of DNA and dextran. On\nthe same samples under the same conditions, we perform DDM and single-molecule\ntracking on embedded fluorescent-labeled DNA molecules immediately before and\nafter bulk measurements. We show DNA-dextran composites exhibit unexpected\nnon-monotonic dependences of bulk viscoelasticity and molecular-level transport\nproperties on the fraction of DNA comprising the composites, with\ncharacteristics that are strongly dependent on the DNA topology. We rationalize\nour results as arising from stretching and bundling of linear DNA versus\ncompaction, swelling, and threading of rings driven by dextran-mediated\ndepletion interactions."
    },
    {
        "anchor": "The effect of internal and global modes on the radial distribution\n  function of confined semiflexible polymers: The constraints imposed by nano- and microscale confinement on the\nconformational degrees of freedom of thermally fluctuating biopolymers are\nutilized in contemporary nano-devices to specifically elongate and manipulate\nsingle chains. A thorough theoretical understanding and quantification of the\nstatistical conformations of confined polymer chains is thus a central concern\nin polymer physics. We present an analytical calculation of the radial\ndistribution function of harmonically confined semiflexible polymers in the\nweakly bending limit. Special emphasis has been put on a proper treatment of\nglobal modes, i.e. the possibility of the chain to perform global movements\nwithin the channel. We show that the effect of these global modes significantly\nimpacts the chain statistics in cases of weak and intermediate confinement.\nComparing our analytical model to numerical data from Monte Carlo simulations\nwe find excellent agreement over a broad range of parameters.",
        "positive": "Evidence for a disorder driven phase transition in the condensation of\n  4He in aerogels: We report on thermodynamic and optical measurements of the condensation\nprocess of $^4$He in three silica aerogels of different microstructures. For\nthe two base-catalysed aerogels, the temperature dependence of the shape of\nadsorption isotherms and of the morphology of the condensation process show\nevidence of a disorder driven transition, in agreement with recent theoretical\npredictions. This transition is not observed for a neutral-catalysed aerogel,\nwhich we interpret as due to a larger disorder in this case."
    },
    {
        "anchor": "Polarization of Dielectrics by Acceleration: We argue that acceleration induces electric polarization in usual\ndielectrics. Both accelerations in superfluid participate in the medium\npolarization. Excitations contribution to the polarization is calculated at low\ntemperatures. Estimates of the effect show order of magnitude agreement with\nrecent experimental results on electric effect of superflow.",
        "positive": "Diffusing-Wave Spectroscopy in a Standard Dynamic Light Scattering Setup: Diffusing-Wave Spectroscopy (DWS) treats the transport of photons through\nturbid samples as a diffusion process, thereby making it possible to extract\nthe dynamics of scatterers from measured correlation functions. The analysis of\nDWS data requires knowledge of the path length distribution of photons\ntraveling through the sample. While for flat sample cells this path length\ndistribution can be readily expressed in analytical form, no such expression is\navailable for cylindrical sample cells. DWS measurements have therefore\ntypically relied on dedicated setups that use flat sample cells. Here we show\nhow DWS measurements, in particular DWS-based microrheology measurements, can\nbe performed in standard dynamic light scattering setups that use cylindrical\nsample cells. To do so we perform simple random walk simulations which yield\nnumerical predictions of the path length distribution as a function of both the\ntransport mean free path and the detection angle. This information is used in\nexperiments to extract the mean-square displacement of tracer particles in the\nmaterial, as well as the resulting frequency-dependent viscoelastic response.\nAn important advantage of our approach is that by measuring at different\ndetection angles, the average photon path length can be varied. Using a single\nsample cell, this gives access to a wider range of length and time scales than\nobtained in a conventional DWS setup. Such angle-dependent measurements also\noffer an important consistency check, as for all detection angles the DWS\nanalysis should yield the same tracer dynamics, even though the respective path\nlength distributions are very different. We validate our approach by performing\nmeasurements both on aqueous suspensions of tracer particles and on solid-like\ngelatin samples, for which we find our DWS-based microrheology data to be in\nexcellent agreement with rheological measurements."
    },
    {
        "anchor": "Langevin simulations of a model for ultrathin magnetic films: We show results from simulations of the Langevin dynamics of a\ntwo-dimensional scalar model with competing interactions for ultrathin magnetic\nfilms. We find a phase transition from a high temperature disordered phase to a\nlow temperature phase with both positional and orientational orders. Both kinds\nof order emerge at the same temperature, probably due to the isotropy of the\nmodel Hamiltonian. In the low temperature phase orientational correlations show\nlong range order while positional correlations show only quasi-long-range order\nin a wide temperature range. The orientational correlation length and the\nassociated susceptibility seem to diverge with power laws at the transition.\nWhile at zero temperature the system exhibits stripe long range order, as\ntemperature grows we observe the proliferation of different kinds of\ntopological defects that ultimately drive the system to the disordered phase.\nThe magnetic structures observed are similar to experimental results on\nultrathin ferromagnetic films.",
        "positive": "Melting transition in lipid vesicles functionalised by mobile DNA\n  linkers: We study phase behaviours of lipid--bilayer vesicles functionalised by\nligand--receptor complexes made of synthetic DNA by introducing a modelling\nframework and a dedicated experimental platform. In particular, we perform\nMonte Carlo simulations that combine a coarse grained description of the lipid\nbilayer with state of art analytical models for multivalent ligand--receptor\ninteractions. Using density of state calculations, we derive the partition\nfunction in pairs of vesicles and compute the number of ligand--receptor bonds\nas a function of temperature. Numerical results are compared to microscopy and\nfluorimetry experiments on Large Unilamellar Vesicles decorated by DNA linkers\ncarrying complementary overhangs. We find that vesicle aggregation is\nsuppressed when the total number of linkers falls below a threshold value.\nWithin the model proposed here, this is due to the higher configurational costs\nrequired to form inter--vesicle bridges as compared to intra-vesicle loops,\nwhich are in turn related to membrane deformability. Our findings and our\nnumerical/experimental methodologies are applicable to the rational design of\nliposomes used as functional materials and drug delivery applications, as well\nas to study inter-membrane interactions in living systems, such as cell\nadhesion."
    },
    {
        "anchor": "Phase transitions study of the liquid crystal DIO with a ferroelectric\n  nematic, a nematic and an intermediate phase and of mixtures with the\n  ferroelectric nematic compound RM734 by adiabatic scanning calorimetry: Adiabatic scanning calorimetry (ASC) is capable of providing simultaneously\nthe specific enthalpy h(T) and the specific heat capacity cp(T), and is an\nimportant tool to determine the order of transitions and to render\nhigh-resolution information on pretransitional thermal behavior. Here we report\non ASC results on the compound DIO and on mixtures with RM734. Both compounds\nexhibit a low-temperature ferroelectric nematic phase (NF) and a\nhigh-temperature paraelectric nematic (N). In DIO these two phases are\nseparated by an intermediate phase (Nx). Detailed data of h(T) and cp(T),\nindicated that the intermediate phase was present in all mixtures over the\ncomplete composition range, albeit with strongly decreasing temperature width\nwith decreasing mole fraction of DIO (xDIO). The xDIO dependence of the two\ntransitions could be well described by a quadratic function and both\ntransitions were weakly first order. The true latent heat of the Nx-N\ntransition of DIO was as low as 0.0075 +/- 0.0005 J/g and 0.23 +/- 0.03 J/g for\nthe NF-Nx transition, about twice the previously reported value of 0.115 J/g\nfor the NF-N transition in RM734. In the mixtures both transition latent heats\ndecrease gradually with decreasing xDIO. At all the Nx-N transitions\npretransition fluctuation effects are absent and these transitions are purely\nbut very weakly first order. As in RM734 the transition from the NF to the\nhigher temperature phase exhibits substantial pretransitional behaviour. Power\nlaw analysis of cp(T) resulted in an effective critical exponent of 0.88 +/-\n0.10 for DIO and this value decreased in mixtures with decreasing xDIO towards\n0.50 +/- 0.05 reported for RM734. Ideal mixture analysis of the phase diagram\nwas consistent with ideal mixture behavior for the total transition enthalpy\nchange",
        "positive": "Vesicle dynamics in elongation flow: Wrinkling instability and bud\n  formation: We present experimental results on the relaxation dynamics of vesicles\nsubjected to a time-dependent elongation flow. We observed and characterized a\nnew instability, which results in the formation of higher order modes of the\nvesicle shape (wrinkles), after a switch in the direction of the gradient of\nthe velocity. This surprising generation of membrane wrinkles can be explained\nby the appearance of a negative surface tension during the vesicle deflation,\ndue to compression in a sign-switching transient. Moreover, the formation of\nbuds in the vesicle membrane has been observed in the vicinity of the dynamical\ntransition point."
    },
    {
        "anchor": "Mathematical Modeling of Electrolyte Flow Dynamic Patterns and\n  Volumetric Flow Penetrations in the Flow Channel over Porous Electrode\n  Layered System in Vanadium Flow Battery with Serpentine Flow Field Design: In this work, a two-dimensional mathematical model is developed to study the\nflow patterns and volumetric flow penetrations in the flow channel over the\nporous electrode layered system in vanadium flow battery with serpentine flow\nfield design. The flow distributions at the interface between the flow channel\nand porous electrode are examined. It is found that the non-linear pressure\ndistributions can distinguish the interface flow distributions under the ideal\nplug flow and ideal parabolic flow inlet boundary conditions. However, the\nvolumetric flow penetration within the porous electrode beneath the flow\nchannel through the integration of interface flow velocity reveals that this\nvalue is identical under both ideal plug flow and ideal parabolic flow inlet\nboundary conditions. The volumetric flow penetrations under the advection\neffects of flow channel and landing/rib are estimated. The maximum current\ndensity achieved in the flow battery can be predicted based on the 100% amount\nof electrolyte flow reactant consumption through the porous electrode beneath\nboth flow channel and landing channel. The corresponding theoretical maximum\ncurrent densities achieved in vanadium flow battery with one and three layers\nof SGL 10AA carbon paper electrode have reasonable agreement with experimental\nresults under a proper permeability.",
        "positive": "Mapping continuous potentials to discrete forms: The optimal conversion of a continuous inter-particle potential to a discrete\nequivalent is considered here. Existing and novel algorithms are evaluated to\ndetermine the best technique for creating accurate discrete forms using the\nminimum number of discontinuities. This allows the event-driven molecular\ndynamics technique to be efficiently applied to the wide range of continuous\nforce models available in the literature, and facilitates a direct comparison\nof event-driven and time-driven molecular dynamics. The performance of the\nproposed conversion techniques are evaluated through application to the\nLennard-Jones model. A surprising linear dependence of the computational cost\non the number of discontinuities is found, allowing accuracy to be traded for\nspeed in a controlled manner. Excellent agreement is found for static and\ndynamic properties using a relatively low number of discontinuities. For the\nLennard-Jones potential, the optimized discrete form outperforms the original\ncontinuous form at gas densities but is significantly slower at higher\ndensities."
    },
    {
        "anchor": "Two-dimensional hydrodynamic lattice-gas simulations of binary\n  immiscible and ternary amphiphilic fluid flow through porous media: The behaviour of two dimensional binary and ternary amphiphilic fluids under\nflow conditions is investigated using a hydrodynamic lattice gas model. After\nthe validation of the model in simple cases (Poiseuille flow, Darcy's law for\nsingle component fluids), attention is focussed on the properties of binary\nimmiscible fluids in porous media. An extension of Darcy's law which explicitly\nadmits a viscous coupling between the fluids is verified, and evidence of\ncapillary effects are described. The influence of a third component, namely\nsurfactant, is studied in the same context. Invasion simulations have also been\nperformed. The effect of the applied force on the invasion process is reported.\nAs the forcing level increases, the invasion process becomes faster and the\nresidual oil saturation decreases. The introduction of surfactant in the\ninvading phase during imbibition produces new phenomena, including\nemulsification and micellisation. At very low fluid forcing levels, this leads\nto the production of a low-resistance gel, which then slows down the progress\nof the invading fluid. At long times (beyond the water percolation threshold),\nthe concentration of remaining oil within the porous medium is lowered by the\naction of surfactant, thus enhancing oil recovery. On the other hand, the\nintroduction of surfactant in the invading phase during drainage simulations\nslows down the invasion process -- the invading fluid takes a more tortuous\npath to invade the porous medium -- and reduces the oil recovery (the residual\noil saturation increases).",
        "positive": "Which Interactions Dominate in Active Colloids?: Despite a mounting evidence that the same gradients which active colloids use\nfor swimming, induce important cross-interactions (phoretic interaction), they\nare still ignored in most many-body descriptions, perhaps to avoid complexity\nand a zoo of unknown parameters. Here we derive a simple model, which reduces\nphoretic far-field interactions to a pair-interaction whose strength is mainly\ncontrolled by one genuine parameter (swimming speed). The model suggests that\nphoretic interactions are generically important for autophoretic colloids\n(unless effective screening of the phoretic fields is strong) and should\ndominate over hydrodynamic interactions for the typical case of half-coating\nand moderately nonuniform surface mobilities. Unlike standard minimal models,\nbut in accordance with canonical experiments, our model generically predicts\ndynamic clustering in active colloids at low density. This suggests that\ndynamic clustering can emerge from the interplay of screened phoretic\nattractions and active diffusion."
    },
    {
        "anchor": "First-order phase transition in the tethered surface model on a sphere: We show that the tethered surface model of Helfrich and Polyakov-Kleinert\nundergoes a first-order phase transition separating the smooth phase from the\ncrumpled one. The model is investigated by the canonical Monte Carlo\nsimulations on spherical and fixed connectivity surfaces of size up to N=15212.\nThe first-order transition is observed when N>7000, which is larger than those\nin previous numerical studies, and a continuous transition can also be observed\non small-sized surfaces. Our results are, therefore, consistent with those\nobtained in previous studies on the phase structure of the model.",
        "positive": "Fluctuation spectrum of quasispherical membranes with force-dipole\n  activity: The fluctuation spectrum of a quasi-spherical vesicle with active membrane\nproteins is calculated. The activity of the proteins is modeled as the proteins\npushing on their surroundings giving rise to non-local force distributions.\nBoth the contributions from the thermal fluctuations of the active protein\ndensities and the temporal noise in the individual active force distributions\nof the proteins are taken into account. The noise in the individual force\ndistributions is found to become significant at short wavelengths."
    },
    {
        "anchor": "Wettability and Swelling Behavior of a Weak Polybasic Brush: Influence\n  of Divalent Salts in the Environment: We have studied the response of surface properties and swelling behaviors of\nannealed poly(2-vinyl pyridine) (P2VP) brushes covalently tethered to solid\nplanar surfaces to divalent salts in aqueous solutions at varied pH values.\nResults derived from the quartz crystal microbalance technique, atomic force\nmicroscope and contact angle goniometry indicate that annealed polybase brushes\nundergo conformational transitions upon addition of divalent salts over a wide\nrange of pH values below pKa: at low ionic strength, polybase brushes swell\nupon salts addition; at high ionic strength, polybase brushes collapse with\nsalts addition. The extent and sensitive range of brushes conformational\ntransition induced by divalent ions are found to be grater and broader than\nthat caused by monovalent ions at similar ionic strength, indicating stronger\neffects on screening, osmotic pressure and bridging interaction. In addition,\nwetting measurements indicate that polybase-divalent counterions interactions\ncan be used to switch surface characteristics from hydrophilic to hydrophobic\nin a predictable manner. The immediate implications of these experimental\nresults are related to design of \"smart\" surfaces with controllable charge\ndistribution, membrane thickness and wettability.",
        "positive": "Transverse excitations and zigzag transition in quasi-1D hard-disk\n  system: Molecular dynamics computer simulations of collective excitations in a system\nof hard disks confined to a narrow channel of the specific width, that\nresembles 2D triangular lattice at disk close packing, are performed. We found\nthat transverse excitations, which for hard-disk system are absent in the limit\nof 1D and are of acoustic nature in the limit of 2D, in the case of q1D\nhard-disk system emerge in the form of transverse optical excitations and could\nbe considered as a tool to detect the structural transition to a zigzag\nordering. By analyzing density evolution of longitudinal static structure\nfactor and pair distribution function we have shown that driving force of\nzigzag ordering is caging phenomenon that in the case of hard-disk system is\ngoverned by excluded volume interaction with first and second neighbors and is\nof entropic origin."
    },
    {
        "anchor": "Topologically Protected Steady Cycles in an Ice-Like Mechanical\n  Metamaterial: Competing ground states may lead to topologically constrained excitations\nsuch as domain walls or quasiparticles, which govern metastable states and\ntheir dynamics. Domain walls and more exotic topological excitations are well\nstudied in magnetic systems such as artificial spin ice, in which nanoscale\nmagnetic dipoles are placed on geometrically frustrated lattices, giving rise\nto highly degenerate ground states. We propose a mechanical spin-ice\nconstructed from a lattice of floppy, bistable square unit cells. We compare\nthe domain wall excitations that arise in this metamaterial to their magnetic\ncounterparts, finding that new behaviors emerge in this overdamped mechanical\nsystem. By tuning the ratios of the internal elements of the unit cell, we\ncontrol the curvature and propagation speed of internal domain walls. We change\nthe domain wall morphology from a binary, strictly spin-like regime, to a more\ncontinuous, elastic regime. In the elastic regime, we inject, manipulate, and\nexpel domain walls via textured forcing at the boundaries. The system exhibits\ndynamical hysteresis, and we find a first-order dynamical transition as a\nfunction of the driving frequency. We demonstrate a forcing protocol that\nproduces multiple, topologically-distinct steady cycles, which are protected by\nthe differences in their internal domain wall arrangements. These distinct\nsteady cycles rapidly proliferate as the complexity of the applied forcing\ntexture is increased, thus suggesting that such mechanical systems could serve\nas useful model systems to study multistability, glassiness, and memory in\nmaterials.",
        "positive": "Rhythmic cluster generation in strongly driven colloidal dispersions: We study the response of a nematic colloidal dispersion of rods to a driven\nprobe particle which is dragged with high speed through the dispersion\nperpendicular to the nematic director. In front of the dragged particle,\nclusters of rods are generated which rhythmically grow and dissolve by\nrotational motion. We find evidence for a mesoscopic cluster-cluster\ncorrelation length, {\\em independent} of the imposed drag speed. Our results\nare based on non-equilibrium Brownian dynamics computer simulations and in line\nwith a dynamical scaling theory."
    },
    {
        "anchor": "Microswimmers knead nematic into cholesteric: The hydrodynamic stresses created by active particles can destabilise\norientational order present in the system. This is manifested, for example, by\nthe appearance of a bend instability in active nematics or in\nquasi-2-dimensional living liquid crystals consisting of swimming bacteria in\nthin nematic films. Using large-scale scale hydrodynamics simulations, we study\na system consisting of spherical microswimmers within a 3-dimensional nematic\nliquid crystal. We observe a spontaneous chiral symmetry breaking, where the\nuniform nematic state is kneaded into a continously twisting state,\ncorresponding to a helical director configuration akin to a cholesteric liquid\ncrystal. The transition arises from the hydrodynamic coupling between the\nliquid crystalline elasticity and the swimmer flow fields, leading to a\ntwist-bend instability of the nematic order. It is observed for both pusher\n(extensile) and puller (contractile) swimmers. Further, we show that the liquid\ncrystal director and particle trajectories are connected: in the cholesteric\nstate the particle trajectories become helicoidal.",
        "positive": "Motor-driven advection competes with crowding to drive spatiotemporally\n  heterogeneous transport in cytoskeleton composites: The cytoskeleton -- a composite network of biopolymers, molecular motors, and\nassociated binding proteins -- is a paradigmatic example of active matter.\nParticle transport through the cytoskeleton can range from anomalous and\nheterogeneous subdiffusion to superdiffusion and advection. Yet, recapitulating\nand understanding these properties -- ubiquitous to the cytoskeleton and other\nout-of-equilibrium soft matter systems -- remains challenging. Here, we combine\nlight sheet microscopy with differential dynamic microscopy and single-particle\ntracking to elucidate anomalous and advective transport in\nactomyosin-microtubule composites. We show that particles exhibit multi-mode\ntransport that transitions from pronounced subdiffusion to superdiffusion at\ntunable crossover timescales. Surprisingly, while higher actomyosin content\nenhances superdiffusivity, it also markedly increases the degree of\nsubdiffusion at short timescales and generally slows transport. Corresponding\ndisplacement distributions display unique combinations of non-Gaussianity,\nasymmetry, and non-zero modes, indicative of directed advection coupled with\ncaged diffusion and hopping. At larger spatiotemporal scales, particles undergo\nsuperdiffusion which generally increases with actomyosin content, in contrast\nto normal, yet faster, diffusion without actomyosin. Our specific results shed\nimportant new light on the interplay between non-equilibrium processes,\ncrowding and heterogeneity in active cytoskeletal systems. More generally, our\napproach is broadly applicable to active matter systems to elucidate transport\nand dynamics across scales."
    },
    {
        "anchor": "Collective waves in dense and confined microfluidic droplet arrays: Excitation mechanisms for collective waves in confined dense one-dimensional\nmicrofluidic droplet arrays are investigated by experiments and computer\nsimulations. We demonstrate that distinct modes can be excited by creating\nspecific `defect' patterns in flowing droplet trains. Excited longitudinal\nmodes exhibit a short-lived cascade of pairs of laterally displacing droplets.\nTransversely excited modes obey the dispersion relation of microfluidic phonons\nand induce a coupling between longitudinal and transverse modes, whose origin\nis the hydrodynamic interaction of the droplets with the confining walls.\nMoreover, we investigate the long-time behaviour of the oscillations and\ndiscuss possible mechanisms for the onset of instabilities. Our findings\ndemonstrate that the collective dynamics of microfluidic droplet ensembles can\nbe studied particularly well in dense and confined systems. Experimentally, the\nability to control microfluidic droplets may allow to modulate the refractive\nindex of optofluidic crystals which is a promising approach for the production\nof dynamically programmable metamaterials.",
        "positive": "Surface layering of liquids: The role of surface tension: Recent measurements show that the free surfaces of liquid metals and alloys\nare always layered, regardless of composition and surface tension; a result\nsupported by three decades of simulations and theory. Recent theoretical work\nclaims, however, that at low enough temperatures the free surfaces of all\nliquids should become layered, unless preempted by bulk freezing. Using x-ray\nreflectivity and diffuse scattering measurements we show that there is no\nobservable surface-induced layering in water at T=298 K, thus highlighting a\nfundamental difference between dielectric and metallic liquids. The\nimplications of this result for the question in the title are discussed."
    },
    {
        "anchor": "Soret driven convection in a colloidal solution heated from above at\n  very large solutal Rayleigh number: Convection in a colloidal suspension with a large negative separation ratio\nis studied experimentally by heating from above. Shadowgraph observation at\nvery large solutal Rayleigh numbers are reported as a function of time. Fast\nrelaxation oscillations are reported for the root mean square value of the\nshadowgraph intensity. While pure fluids exhibit a transition to turbulent\nconvection for Rayleigh number of about 10^6, stable spoke-pattern planform\nwith up and down columnar flows are observed up to solutal Rayleigh numbers of\nthe order of 10^9. It is suggested that the surprising stability of the\nplanform against turbulence is due to nonlinear focusing arising from the\nconcentration dependence of the diffusion coefficient.",
        "positive": "Molecular Dynamics Study of Polarizable Ion Models for Molten AgBr: Three different polarizable ion models for molten AgBr have been studied by\nmolecular dynamics simulations. The three models are based on a rigid ion model\n(RIM) with a pair potential of the type proposed by Vashishta and Rahman for\nalpha-AgI, to which the induced dipole polarization of the ions is added. In\nthe first (PIM1), the dipole moments are only induced by the local electric\nfield; while in the other two (PIM1s and PIM2s), a short-range overlap induced\npolarization opposes the electrically induced dipole moments. In the PIM1 and\nthe PIM1s only the anions are assumed polarizable, while in the PIM2s both\nspecies are polarizable. Long molecular dynamics simulations show that the\nPIM2s is an unphysical model since, for some improbable but possible critical\nconfigurations, the ions become infinitely polarized. The results of using the\nPIM1, the PIM1s, as well as those of the simple RIM, have been compared for the\nstatic structure and ionic transport properties. The PIM1 reproduces the broad\nmain peak of the total structure factor present in the neutron diffraction\ndata, although the smoothed three-peak feature of this broad peak is slightly\noverestimated. The structural results for the PIM1s are intermediate between\nthose for the RIM and the PIM1, but fail to reproduce the experimental features\nwithin the broad principal peak. Concerning the ionic transport properties, the\nvalue of the conductivity obtained using PIM1 is in good agreement with\nexperimental values, while the self-diffusion coefficients and the conductivity\nfor the PIM1s are lower than the corresponding values using the PIM1 and the\nRIM."
    },
    {
        "anchor": "Interaction from Structure using Machine Learning: in and out of\n  Equilibrium: Prediction of pair potential given a typical configuration of an interacting\nclassical system is a difficult inverse problem. There exists no exact result\nthat can predict the potential given the structural information. We demonstrate\nthat using machine learning (ML) one can get a quick but accurate answer to the\nquestion: which pair potential lead to the given structure (represented by pair\ncorrelation function)? We use artificial neural network (NN) to address this\nquestion and show that this ML technique is capable of providing very accurate\nprediction of pair potential irrespective of whether the system is in a\ncrystalline, liquid or gas phase. We show that the trained network works well\nfor sample system configurations taken from both equilibrium and out of\nequilibrium simulations (active matter systems) when the later is mapped to an\neffective equilibrium system with a modified potential. We show that the ML\nprediction about the effective interaction for the active system is not only\nuseful to make prediction about the MIPS (motility induced phase separation)\nphase but also identifies the transition towards this state.",
        "positive": "Low Voltage Reversible Electrowetting Exploiting Lubricated Polymer\n  Honeycomb Substrates: Low-voltage electrowetting-on-dielectric scheme realized with lubricated\nhoneycomb polymer surfaces is reported. Polycarbonate honeycomb reliefs\nmanufactured with the breath-figures self-assembly were impregnated with\nsilicone and castor oils. The onset of the reversible electrowetting for\nsilicone oil impregnated substrates occurred at 35 V, whereas for castor oil\nimpregnated ones it took place at 80 V. The semi-quantitative analysis of\nelectrowetting of impregnated surfaces is proposed."
    },
    {
        "anchor": "J-shaped stress-strain diagram of collagen fibers: Frame tension of\n  triangulated surfaces with fixed boundaries: We present Monte Carlo data of the stress-strain diagrams obtained using two\ndifferent triangulated surface models. The first is the canonical surface model\nof Helfrich and Polyakov (HP), and the second is a Finsler geometry (FG) model.\nThe shape of the experimentally observed stress-strain diagram is called\nJ-shaped. Indeed, the diagram has a plateau for the small strain region and\nbecomes linear in the relatively large strain region. Because of this highly\nnon-linear behavior, the J-shaped diagram is far beyond the scope of the\nordinary theory of elasticity. Therefore, the mechanism behind the J-shaped\ndiagram still remains to be clarified, although it is commonly believed that\nthe collagen degrees of freedom play an essential role. We find that the FG\nmodeling technique provides a coarse-grained picture for the interaction\nbetween the collagen and the bulk material. The role of the directional degrees\nof freedom of collagen molecules or fibers can be understood in the context of\nFG modeling. We also discuss the reason for why the J-shaped diagram cannot\n(can) be explained by the HP (FG) model.",
        "positive": "Shape characteristics of the aggregates formed by amphiphilic stars in\n  water: dissipative particle dynamics study: We study the effect of the molecular architecture of amphiphilic star\npolymers on the shape of aggregates they form in water. Both solute and solvent\nare considered at a coarse-grained level by means of dissipative particle\ndynamics simulations. Four different molecular architectures are considered:\nthe miktoarm star, two different diblock stars and a group of linear diblock\ncopolymers, all of the same composition and molecular weight. Aggregation is\nstarted from a closely packed bunch of $N_{\\text a}$ molecules immersed into\nwater. In most cases, a single aggregate is observed as a result of\nequilibration, and its shape characteristics are studied depending on the\naggregation number $N_{\\text a}$. Four types of aggregate shape are observed:\nspherical, rod-like and disc-like micelle and a spherical vesicle. We estimate\n\"phase boundaries\" between these shapes depending on the molecular\narchitecture. Sharp transitions between aspherical micelle and a vesicle are\nfound in most cases. The pretransition region shows large amplitude\noscillations of the shape characteristics with the oscillation frequency\nstrongly dependent on the molecular architecture."
    },
    {
        "anchor": "New type of microengine using internal combustion of hydrogen and oxygen: Microsystems become part of everyday life but their application is restricted\nby lack of strong and fast motors (actuators) converting energy into motion.\nFor example, widespread internal combustion engines cannot be scaled down\nbecause combustion reactions are quenched in a small space. Here we present an\nactuator with the dimensions 100x100x5 um^3 that is using internal combustion\nof hydrogen and oxygen as part of its working cycle. Water electrolysis driven\nby short voltage pulses creates an extra pressure of 0.5-4 bar for a time of\n100-400 us in a chamber closed by a flexible membrane. When the pulses are\nswitched off this pressure is released even faster allowing production of\nmechanical work in short cycles. We provide arguments that this unexpectedly\nfast pressure decrease is due to spontaneous combustion of the gases in the\nchamber. This actuator is the first step to truly microscopic combustion\nengines.",
        "positive": "Elasticity-driven collective motion in active solids and active crystals: We introduce a simple model of self-propelled agents connected by linear\nsprings, with no explicit alignment rules. Below a critical noise level, the\nagents self-organize into a collectively translating or rotating group. We\nderive analytical stability conditions for the translating state in an elastic\nsheet approximation. We propose an elasticity-based mechanism that drives\nconvergence to collective motion by cascading self-propulsion energy towards\nlower-energy modes. Given its simplicity and ubiquity, such mechanism could\nplay a relevant role in various biological and robotic swarms."
    },
    {
        "anchor": "Onset of glassiness in two-dimensional ring polymers: interplay of\n  stiffness and crowding: The effect of ring stiffness and pressure on the glassy dynamics of a thermal\nassembly of two-dimensional ring polymers is investigated using extensive\ncoarse-grained molecular dynamics simulations. In all cases, dynamical slowing\ndown is observed with increasing pressure and thereby a phase space for\nequilibrium dynamics is identified in the plane of obtained monomer density and\nring stiffness. When the rings are highly flexible, i.e. low ring stiffness,\nglassiness sets in via crowding of crumpled polymers which take a globular\nform. In contrast, at large ring stiffness, when the rings tend to have large\nasphericity under compaction, we observe the emergence of local domains having\norientational ordering, at high pressures. Thus, our simulations highlight how\nvarying the deformability of rings leads to contrasting mechanisms in driving\nthe system towards the glassy regime.",
        "positive": "Threading the spindle: a geometric study of chiral liquid crystal\n  polymer microparticles: Polymeric particles are strong candidates for designing artificial materials\ncapable of emulating the complex twisting-based functionality observed in\nbiological systems. In this letter, we provide the first detailed investigation\nof the swelling behavior of bipolar polymer liquid crystalline microparticles.\nDeswelling from the spherical bipolar configuration causes the microparticle to\ncontract anisotropically and twist in the process, resulting in a twisted\nspindle shaped structure. We propose a model to describe the observed spiral\npatterns and twisting behavior."
    },
    {
        "anchor": "Far-From-Equilibrium Physics: An Overview: Isolated systems tend to evolve towards equilibrium, a special state that has\nbeen the focus of many-body research for a century. Yet much of the richness of\nthe world around us arises from conditions far from equilibrium. Phenomena such\nas turbulence, earthquakes, fracture, and life itself occur only far from\nequilibrium. Subjecting materials to conditions far from equilibrium leads to\notherwise unattainable properties. For example, rapid cooling is a key process\nin manufacturing the strongest metallic alloys and toughest plastics. Processes\nthat occur far from equilibrium also create some of the most intricate\nstructures known, from snowflakes to the highly organized structures of life.\nWhile much is understood about systems at or near equilibrium, we are just\nbeginning to uncover the basic principles governing systems far from\nequilibrium.",
        "positive": "Probing non-affine expansion with light scattering: In disordered materials under mechanical stress, the produced deformation can\ndeviate from the affine one already in the elastic regime. The nonaffine\ncontribution was observed and characterized in numerical simulations for\nvarious systems. However, low amplitude of nonaffinity and its local character\nmakes the experimental study challenging. We present a novel method on the\nbased on a phase compensation of the wave scattered from a dilated amorphous\nmaterial using fine wavelength tuning of the optical probe beam. Using a glass\nfrit as a sample, we provide complete reversibility of the material deformation\nwhich enables to confirm the occurrence of nonaffinity in the elastic regime.\nWe develop a model for the coupled effect of the thermal expansion/contraction\nof the material and the dilatation of the incident wavelength which allows us\nto estimate the magnitude of the nonaffine displacement and the spatial extent\nof its correlation domain."
    },
    {
        "anchor": "Spontaneous symmetry breaking induced unidirectional rotation of\n  chain-grafted colloid in the active bath: Exploiting the energy of randomly moving active agents such as bacteria is a\nfascinating way to power a microdevice. Here we show, by simulations, that a\nchain-grafted disk-like colloid can rotate unidirectionally when immersed in a\nthin film of active particle suspension. The spontaneous symmetry breaking of\nchain configurations is the origin of the unidirectional rotation. Long\npersistence time, large propelling force and/or small rotating friction are\nkeys to keeping the broken symmetry and realizing the rotation. In the rotating\nstate, we find very simple linear relations, e.g. between mean angular speed\nand propelling force. The time-evolving asymmetry of chain configurations\nreveals that there are two types of non-rotating state. Our findings provide\nnew insights into the phenomena of spontaneous symmetry breaking in active\nsystems with flexible objects and also open the way to conceive new\nsoft/deformable microdevices.",
        "positive": "NMR Experiments on a Three-Dimensional Vibrofluidized Granular Medium: A three-dimensional granular system fluidized by vertical container\nvibrations was studied using pulsed field gradient (PFG) NMR coupled with\none-dimensional magnetic resonance imaging (MRI). The system consisted of\nmustard seeds vibrated vertically at 50 Hz, and the number of layers N_ell <= 4\nwas sufficiently low to achieve a nearly time-independent granular fluid. Using\nNMR, the vertical profiles of density and granular temperature were directly\nmeasured, along with the distributions of vertical and horizontal grain\nvelocities. The velocity distributions showed modest deviations from\nMaxwell-Boltzmann statistics, except for the vertical velocity distribution\nnear the sample bottom which was highly skewed and non-Gaussian. Data taken for\nthree values of N_ell and two dimensionless accelerations Gamma=15,18 were fit\nto a hydrodynamic theory, which successfully models the density and temperature\nprofiles including a temperature inversion near the free upper surface."
    },
    {
        "anchor": "Non-affine bending mode of thin cylindrical tubes: We discuss the response of thin cylindrical tubes to small indentations. The\nstretching-free embedding of these surfaces is completely determined by the\nembedding of one edge curve, thus reducing their bending response to an\neffectively one dimensional problem. We obtain that in general thin cylindrical\ntubes will bend non-uniformly in response to an indentation normal to their\nsurface. As a consequence, their local bending stiffness, as measured by\nindenting at various locations along their axis, is predicted to peak at the\ncenter and decrease by a universal factor of 4 at either end of the tube. This\ncharacteristic spatial profile of the bending stiffness variation allows a\ndirect determination of the bending modulus of very thin tubes that are shorter\nthan their pinch persistence length, $l_{p}\\propto R^{3/2}/t^{1/2}$, where $R$\nis the tube diameter and $t$ its wall thickness. We compare our results with\nexperiments performed on rolled-up stainless steel sheets.",
        "positive": "Rigidity and fracture of fibrous double networks: Tunable mechanics and fracture resistance are hallmarks of biological tissues\nand highly desired in engineered materials. To elucidate the underlying\nmechanisms, we study a rigidly percolating double network (DN) made of a stiff\nand a flexible network. The DN shows remarkable tunability in mechanical\nresponse when the stiff network is just above its rigidity percolation\nthreshold and minimal changes far from this threshold. Further, the DN can be\nmodulated to either be extensible, breaking gradually, or stronger, breaking in\na more brittle fashion by varying the flexible network's concentration."
    },
    {
        "anchor": "Quantitative prediction of the phase diagram of DNA-functionalized\n  nano-colloids: We present a coarse-grained model of DNA-functionalized colloids that is\ncomputationally tractable. Importantly, the model parameters are solely based\non experimental data. Using this highly simplified model, we can predict the\nphase behavior of DNA-functionalized nano-colloids without assuming pairwise\nadditivity of the inter-colloidal interactions. Our simulations show that for\nnano-colloids, the assumption of pairwise additivity leads to substantial\nerrors in the estimate of the free energy of the crystal phase. We compare our\nresults with available experimental data and find that the simulations predict\nthe correct structure of the solid phase and yield a very good estimate of the\nmelting temperature. Current experimental estimates for the contour length and\npersistence length of single-stranded DNA sequences are subject to relatively\nlarge uncertainties. Using the best available estimates, we obtain predictions\nfor the crystal lattice constants that are off by a few percent: this indicates\nthat more accurate experimental data on ssDNA are needed to exploit the full\npower of our coarse-grained approach.",
        "positive": "A Monte Carlo density functional theory for the competition between\n  inter and intramolecular association in inhomogeneous fluids: A monte carlo density functional theory is developed for chain molecules\nwhich both intra and intermolecularly associate. The approach can be applied\nover a range of chain lengths. The theory is validated for the case of an\nassociating 4-mer fluid in a planar hard slit pore. Once validated the new\ntheory is used to study the effect of chain length and temperature on the\ncompetition between intra and intermolecular association near a hard wall. We\nshow that this competition enhances intramolecular association near wall\ncontact and inverts the chain length dependence of the fraction bonded\nintermolecularly in the inhomogeneous region."
    },
    {
        "anchor": "Inverse Design of Simple Pair Potentials for the Self-Assembly of\n  Complex Structures: The synthesis of complex materials through the self-assembly of particles at\nthe nanoscale provides opportunities for the realization of novel material\nproperties. However, the inverse design process to create experimentally\nfeasible interparticle interaction strategies is uniquely challenging. Standard\nmethods for the optimization of isotropic pair potentials tend toward\noverfitting, resulting in solutions with too many features and length scales\nthat are challenging to map to mechanistic models. Here we introduce a method\nfor the optimization of simple pair potentials that minimizes the relative\nentropy of the complex target structure while directly considering only those\nlength scales most relevant for self-assembly. Our approach maximizes the\nrelative information of a target pair distribution function with respect to an\nansatz distribution function via an iterative update process. During this\nprocess, we filter high frequencies from the Fourier spectrum of the pair\npotential, resulting in interaction potentials that are smoother and simpler in\nreal space, and therefore likely easier to make. We show that pair potentials\nobtained by this method assemble their target structure more robustly with\nrespect to optimization method parameters than potentials optimized without\nfiltering.",
        "positive": "Universal catastrophe time distributions of dynamically unstable\n  polymers: Dynamic instability -- the growth, catastrophe, and shrinkage of\nquasi-one-dimensional filaments -- has been observed in multiple biopolymers.\nScientists have long understood the catastrophic cessation of growth and\nsubsequent depolymerization as arising from the interplay of hydrolysis and\npolymerization at the tip of the polymer. Here, we show that for a broad class\nof catastrophe models, the expected catastrophe time distribution is\nexponential. We show that the distribution shape is insensitive to noise, but\nthat depletion of monomers from a finite pool can dramatically change the\ndistribution shape by reducing the polymerization rate. We derive a form for\nthis finite-pool catastrophe time distribution and show that finite-pool\neffects can be important even when the depletion of monomers does not greatly\nalter the polymerization rate."
    },
    {
        "anchor": "Epithelial-substrate coupling strength regulates the landscape of the\n  traction in cohesive monolayers: a parametric study and a revisit to \"size\n  effect\": Epithelial cells can assemble into cohesive colonies and collectively\ninteract with substrates by generating extracellular forces through focal\nadhesions. Recently, a molecularly based thermodynamic model, which integrates\nboth the monolayer elasticity and force-mediated focal adhesion formation, has\nbeen developed to elucidate the regulation of the cellular force landscape\ninduced by the active epithelial-substrate coupling. However, how\nepithelial-substrate coupling strength mediate the landscapes of the traction,\nthe cellular displacement, and the focal adhesion distribution in a cohesive\nmonolayer remains unexamined in details. In this work, we follow the procedures\nby the previous work to re-formulate the free energy of the\nepithelial-substrate system and obtain the thermodynamic steady-state\nequations. We then derive a simplified form of the complete equation system,\nand solve it both semi-analytically and numerically. We find that the parameter\nwhich characterizes the epithelial-substrate coupling strength can\nsignificantly affect the landscapes of the traction the cellular displacement,\nand the focal adhesion distribution. We also revisit the \"size effect\"\naddressed by previous works and demonstrate that such effect is the natural\noutcome of a strong epithelial-substrate coupling without introducing any extra\nfactors. For epithelial-substrate coupling which is not strong enough, the\ncurrently observed \"size effect\" does not hold. A scaling law that determines\nwhether the previously observed \"size effect\" holds is proposed based on our\nmodel.",
        "positive": "Hybrid plasmonic-photonic crystal formed on gel-immobilized colloidal\n  crystal via solvent substitutio: Gel-immobilized colloidal crystals were prepared to obtain hybrid\nplasmonic-photonic crystals, in which electric field enhancement to a greater\nextent than that due to localized surface plasmons (LSP) alone was expected due\nto coupling between LSP and the photonic band. Polystyrene colloidal crystals\nimmobilized by the N-(hydroxymethyl)acrylamide gel were immersed in an aqueous\ndispersion of gold nanoparticles (AuNPs). Then, the gel-immobilized colloidal\ncrystals were picked out and immersed in an ionic liquid mixture. The surfaces\nof the gel-immobilized colloidal crystals immersed in the AuNP dispersion were\nobserved via scanning electron microscopy after this solvent substitution. The\nlattice spacing of the colloidal crystal varied as the composition of the ionic\nliquid mixture was changed. The composition was determined so that the photonic\nband gap wavelength coincided with the LSP wavelength. Further, the reflection\nspectra were measured. Thus, we successfully prepared a hybrid\nplasmonic-photonic crystal."
    },
    {
        "anchor": "Direct measurement of thermophoretic forces: We study the thermophoretic motion of a micron sized single colloidal\nparticle in front of a flat wall by evanescent light scattering. To quantify\nthermophoretic effects we analyse the nonequilibrium steady state (NESS) of the\nparticle in a constant temperature gradient perpendicular to the confining\nwalls. We propose to determine thermophoretic forces from a 'generalized\npotential' associated with the probability distribution of the particle\nposition in the NESS. Experimentally we demonstrate, how this spatial\nprobability distribution is measured and how thermophoretic forces can be\nextracted with 10 fN resolution. By varying temperature gradient and ambient\ntemperature, the temperature dependence of Soret coefficient $S_T(T)$ is\ndetermined for $r = 2.5 \\mu m$ polystyrene and $r = 1.35 \\mu m$ melamine\nparticles. The functional form of $S_T(T)$ is in good agreement with findings\nfor smaller colloids. In addition, we measure and discuss hydrodynamic effects\nin the confined geometry. The theoretical and experimental technique proposed\nhere extends thermophoresis measurements to so far inaccessible particle sizes\nand particle solvent combinations.",
        "positive": "Interference pattern of Bose-condensed gas in a 2D optical lattice: For the Bose-condensed gas confined in a magnetic trap and in a\ntwo-dimensional optical lattice, the non-uniform distribution of atoms in\ndifferent lattice sites is considered based on Gross-Pitaevskii equation. A\npropagator method is used to investigate the time evolution of 2D interference\npatterns after (i)only the optical lattice is swithed off, and (ii)both the\noptical lattice and the magnetic trap are swithed off. An analytical\ndescription on the motion of side peaks in the interference patterns is\npresented by using the density distribution in a momentum space."
    },
    {
        "anchor": "Structural properties of dense hard sphere packings: The structural properties of dense random packings of identical hard spheres\n(HS) are investigated. The bond order parameter method is used to obtain\ndetailed information on the local structural properties of the system for\ndifferent packing fractions $\\phi$, in the range between $\\phi=0.53$ and\n$\\phi=0.72$. A new order parameter, based on the cumulative properties of\nspheres distribution over the rotational invariant $w_6$, is proposed to\ncharacterize crystallization of randomly packed HS systems. It is shown that an\nincrease in the packing fraction of the crystallized HS system first results in\nthe transformation of the individual crystalline clusters into the global\nthree-dimensional crystalline structure, which, upon further densification,\ntransforms into alternating planar layers formed by different lattice types.",
        "positive": "Tagged active particle: probability distribution in a slowly varying\n  external potential is determined by effective temperature obtained from the\n  Einstein relation: We derive a distribution function for the position of a tagged active\nparticle in a slowly varying in space external potential, in a system of\ninteracting active particles. The tagged particle distribution has the form of\nthe Boltzmann distribution but with an effective temperature that replaces the\ntemperature of the heat bath. We show that the effective temperature that\nenters the tagged particle distribution is the same as the effective\ntemperature defined through the Einstein relation, i.e. it is equal to the\nratio of the self-diffusion and tagged particle mobility coefficients. This\nshows that this effective temperature, which is defined through a\nfluctuation-dissipation ratio, is relevant beyond the linear response regime.\nWe verify our theoretical findings through computer simulations. Our theory\nfails when an additional large length scale appears in our active system. This\nlength scale is associated with long-wavelength density fluctuations that\nemerge upon approaching motility-induced phase separation."
    },
    {
        "anchor": "Effective Medium Theory for Mechanical Phase Transitions of Fiber\n  Networks: Networks of stiff fibers govern the elasticity of biological structures such\nas the extracellular matrix of collagen. These networks are known to stiffen\nnonlinearly under shear or extensional strain. Recently, it has been shown that\nsuch stiffening is governed by a strain-controlled athermal but critical phase\ntransition, from a floppy phase below the critical strain to a rigid phase\nabove the critical strain. While this phase transition has been extensively\nstudied numerically and experimentally, a complete analytical theory for this\ntransition remains elusive. Here, we present an effective medium theory (EMT)\nfor this mechanical phase transition of fiber networks. We extend a previous\nEMT appropriate for linear elasticity to incorporate nonlinear effects via an\nanharmonic Hamiltonian. The mean-field predictions of this theory, including\nthe critical exponents, scaling relations and non-affine fluctuations\nqualitatively agree with previous experimental and numerical results.",
        "positive": "Microscopic Picture of Cooperative Processes in Restructuring Gel\n  Networks: Colloidal gel networks are disordered elastic solids that can form even in\nextremely dilute particle suspensions. With interaction strengths comparable to\nthe thermal energy, their stress-bearing network can locally restructure via\nbreaking and reforming interparticle bonds. This allows for yielding,\nself-healing, and adaptive mechanics under deformation. Designing such features\nrequires controlling stress transmission through the complex structure of the\ngel and this is challenging because the link between local restructuring and\noverall response of the network is still missing. Here, we use a space resolved\nanalysis of dynamical processes and numerical simulations of a model gel to\ngain insight into this link. We show that consequences of local bond breaking\npropagate along the gel network over distances larger than the average mesh\nsize. This provides the missing microscopic explanation for why nonlocal\nconstitutive relations are necessary to rationalize the nontrivial mechanical\nresponse of colloidal gels."
    },
    {
        "anchor": "Active Bound States Arise From Transiently Nonreciprocal Pair\n  Interactions: Static nonreciprocal forces between particles generically drive persistent\nmotion reminiscent of self-propulsion. Here, we demonstrate that\nreciprocity-breaking fluctuations about a reciprocal mean coupling strength are\nsufficient to generate this behavior in a minimal two-particle model, with the\nvelocity of the ensuing \\textit{active} bound state being modulated in time\naccording to the nature of these fluctuations. To characterize the ensuing\nnonequilibrium dynamics, we derive exact results for the time-dependent center\nof mass mean-squared displacement and average rate of entropy production for\ntwo simple examples of discrete- and continuous-state fluctuations. We find\nthat the resulting dimer can exhibit unbiased persistent motion akin to that of\nan active particle, leading to a significantly enhanced effective diffusivity.",
        "positive": "Wetting morphologies on an array of fibers of different radii: We investigate the equilibrium morphology of a finite volume of liquid placed\non two parallel rigid fibers of different radii. As observed for identical\nradii fibers, the liquid is either in a column morphology or adopts a drop\nshape depending on the inter-fiber distance. However the cross-sectional area\nand the critical inter-fiber distance at which the transition occurs are both\nmodified by the polydispersity of the fibers. Using energy considerations, we\nanalytically predict the critical inter-fiber distance corresponding to the\ntransition between the column and the drop morphologies occurs. This distance\ndepends both on the radii of the fibers and on the contact angle of the liquid.\nWe perform experiments using a perfectly wetting liquid on two parallel nylon\nfibers: the results are in good agreement with our analytical model. The\nmorphology of the capillary bridges between fibers of different radii is\nrelevant to the modeling of large arrays of polydisperse fibers."
    },
    {
        "anchor": "Buckling of rods with spontaneous twist and curvature: We analyze stability of a thin inextensible elastic rod which has\nnon-vanishing spontaneous generalized torsions in its stress-free state. Two\nclassical problems are studied, both involving spontaneously twisted rods: a\nrectilinear beam compressed by axial forces, and a circular ring subjected to\nuniform radial pressure on its outer perimeter. It is demonstrated that while\nspontaneous twist stabilizes a rectilinear rod against buckling, its presence\nhas an opposite effect on a closed ring.",
        "positive": "Hysteresis and nonequilibrium work theorem for DNA unzipping: We study by using Monte Carlo simulations the hysteresis in unzipping and\nrezipping of a double stranded DNA (dsDNA) by pulling its strands in opposite\ndirections in the fixed force ensemble. The force is increased, at a constant\nrate from an initial value $g_0$ to some maximum value $g_m$ that lies above\nthe phase boundary and then decreased back again to $g_{0}$. We observed\nhysteresis during a complete cycle of unzipping and rezipping. We obtained\nprobability distributions of work performed over a cycle of unzipping and\nrezipping for various pulling rates. The mean of the distribution is found to\nbe close (the difference being within 10%, except for very fast pulling) to the\narea of the hysteresis loop. We extract the equilibrium force versus separation\nisotherm by using the work theorem on repeated non-equilibrium force\nmeasurements. Our method is capable of reproducing the equilibrium and the\nnon-equilibrium force-separation isotherms for the spontaneous rezipping of\ndsDNA."
    },
    {
        "anchor": "Nonlinear response and axisymmetric wave propagation in functionally\n  graded soft electro-active tubes: Soft electro-active (SEA) materials can be designed and manufactured with\ngradients in their material properties, to modify and potentially improve their\nmechanical response in service. Here, we investigate the nonlinear response of,\nand axisymmetric wave propagation in a soft circular tube made of a\nfunctionally graded SEA material and subject to several biasing fields,\nincluding axial pre-stretch, internal/external pressure, and through-thickness\nelectric voltage. We take the energy density function of the material to be of\nthe Mooney-Rivlin ideal dielectric type, with material parameters changing\nlinearly along the radial direction. We employ the general theory of nonlinear\nelectro-elasticity to obtain explicitly the nonlinear response of the tube to\nthe applied fields. To study wave propagation under inhomogeneous biasing\nfields, we formulate the incremental equations of motion within the state-space\nformalism. We adopt the approximate laminate technique to derive the analytical\ndispersion relations for the small-amplitude torsional and longitudinal waves\nsuperimposed on a finitely deformed state. Comprehensive numerical results then\nillustrate that the material gradients and biasing fields have significant\ninfluences on the static nonlinear response and on the axisymmetric wave\npropagation in the tube. This study lays the groundwork for designing SEA\nactuators with improved performance, for tailoring tunable SEA waveguides, and\nfor characterizing non-destructively functionally graded tubular structures.",
        "positive": "Softening of DNA near Melting as Disappearance of an Emergent Property: Near the melting transition the bending elastic constant, $\\kappa$, an\nemergent property of double-stranded DNA (dsDNA), is shown not to follow the\nrod-like scaling for small length $N$. The reduction in $\\kappa$ with\ntemperature is determined by the denatured bubbles for a continuous transition,\ne.g., when the two strands are gaussian, but by the broken bonds near the open\nend in a Y-like configuration for a first-order transition as for strands with\nexcluded volume interactions. In the latter case, a lever rule is operational\nimplying a phase coexistence although dsDNA is known to be a single phase."
    },
    {
        "anchor": "Ferroelectric nematic liquid crystal thermo-motor: A thermal gradient-induced circular motion of particles placed on\nferroelectric nematic liquid crystal sessile drops is demonstrated and\nexplained. Unlike hurricanes and tornadoes that are the prime examples for\nthermal motors and where turbulent flows are apparent, here the texture without\ntracer particles appears completely steady indicating laminar flow. We provide\na simple model showing that the tangential arrangement of the ferroelectric\npolarization combined with the vertical thermal gradient and the\npyroelectricity of the fluid drives the rotation of the tracer particles that\nbecome electrically charged in the fluid. These observations provide a\nfascinating example of the unique nature of fluid ferroelectric liquid\ncrystals.",
        "positive": "Effect of anisotropy on the formation of active particle films: Active colloids belong to a class of non-equilibrium systems where energy\nuptake, conversion and dissipation occurs at the level of individual colloidal\nparticles, which can lead to particles self-propelled motion and surprising\ncollective behavior. Examples include coexistence of vapor and liquid-like\nsteady states for active particles with repulsive interactions only, phenomena\nknown as motility induced phase transition. Similarly to motile unicellular\norganisms, active colloids tend to accumulate at confining surfaces forming\ndense adsorbed films. In this work, we study the structure and dynamics of\naggregates of self-propelled particle near confining solid surfaces, focusing\non the effects of the particle anisotropic interactions. We performed Langevin\ndynamics simulations of two complementary models for active particles:\nellipsoidal particles interacting through Gay-Berne potential, and rod-like\nparticles composed of several repulsive Lennard-Jones beads. We observe a\nnon-monotonic behavior of the structure of clusters formed along the confining\nsurface as a function of the particle aspect ratio, with a film spreading when\nparticles are near spherical, compact clusters with hedgehog-like particle\norientation for more elongated active particles, and a complex dynamical\nbehavior for intermediate aspect ratio. The stabilization time of cluster\nformation along the confining surface also displays a non-monotonic dependence\non the aspect ratio, with a local minimum at intermediate values. Additionally,\nwe demonstrate that the hedgehog-like aggregates formed by Gay-Berne ellipsoids\nexhibit higher structural stability as compared to the ones formed by purely\nrepulsive active rods, which are stable due to the particle activity only."
    },
    {
        "anchor": "Motility of active nematic films driven by \"active anchoring\": We provide a minimal model for an active nematic film in contact with both a\nsolid substrate and a passive isotropic fluid, and explore its dynamics in one\nand two dimensions using a combination of hybrid Lattice Boltzmann simulations\nand analytical calculations. By imposing nematic anchoring at the substrate\nwhile active flows induce a preferred alignment at the interface (\"active\nanchoring\"), we demonstrate that directed fluid flow spontaneously emerges in\ncases where the two anchoring types are opposing. In one dimension, our model\nreduces to an analogue of a loaded elastic column. Here, the transition from a\nstationary to a motile state is akin to the buckling bifurcation, but offers\nthe possilibity to reverse the flow direction for a given set of parameters and\nboundary conditions solely by changing initial conditions. The two-dimensional\nvariant of our model allows for additional tangential instabilities, leading to\nself-assembled propagating surface waves for intermediate activity and for a\ncontinously deforming irregular surface at high activity. Our results might be\nrelevant for designing active microfluidic geometries, but also for\ncurvature-guided self-assembly or switchable diffraction gratings.",
        "positive": "Self-Consistent Field Model Simulations for Statistics of Amorphous\n  Polymer Chains in Crystalline Lamellar Structures: We calculate statistical properties of amorphous polymer chains between\ncrystalline lamellae by self-consistent field model simulations. In our model,\nan amorphous subchain is modelled as a polymer chain of which ends are grafted\nonto the crystal-amorphous interfaces. The crystal-amorphous interfaces are\nexpressed as impenetrable surfaces. We incorporate the interaction between\nsegments to satisfy the incompressible condition for the segment density field.\nThe simulation results show that amorphous polymer chains feel thin potential\nlayers, which are mainly repulsive, near the crystal-amorphous interfaces. The\nimpenetrable and incompressible conditions affect the statistics of polymer\nchains and the chain statistics becomes qualitatively different from the ideal\nGaussian chain statistics without any constraints. We show the effects of the\nsystem size and the graft density to statistical quantities. We also show that\nthe tie subchain statistics obey rather simple statistics."
    },
    {
        "anchor": "Controlling liquid-liquid phase behavior with an active fluid: Demixing of binary liquids is a ubiquitous transition, which is explained\nusing a well-established thermodynamic formalism that requires equality of\nintensive thermodynamics parameters across the phase boundaries. Demixing\ntransitions also occur when binary fluid mixtures are driven away from\nequilibrium, for example, by external shear flow. Predicting demixing\ntransition under non-equilibrium non-potential conditions remains, however, a\nchallenge. We drive liquid-liquid phase separation (LLPS) of attractive DNA\nnanostar molecules away from equilibrium using an internally driven\nmicrotubule-based active fluid. Activity lowers the critical temperature and\nnarrows the coexistence concentrations, but only when there are mechanical\nbonds between the liquid droplets and the reconfiguring active fluid. Similar\nbehaviors are observed in numerical simulations, suggesting that activity\nsuppression of liquid-liquid phase separation is a generic feature of active\nLLPS. Our work describes a platform for building soft active materials with\nfeedback control while also providing insight into cell biology, where phase\nseparation emerged as a ubiquitous self-organizational principle.",
        "positive": "Comment on the paper entitled Limited surface mobility inhibits stable\n  glass formation for 2-ethyl-1-hexanol, published in J. Chem. Phys. 146,\n  203317 (2017): The authors of the paper, Limited surface mobility inhibits stable glass\nformation for 2-ethyl-1-hexanol, J. Chem. Phys. 146, 203317 (2017), encountered\ntwo problems in considering applicability of the Coupling Model. We show in\nthis Comment that these problems do not exist."
    },
    {
        "anchor": "Observation of the Density Minimum in Deeply Supercooled Confined Water: Small angle neutron scattering (SANS) is used to measure the density of heavy\nwater contained in 1-D cylindrical pores of mesoporous silica material\nMCM-41-S-15, with pores of diameter of 15+-1 A. In these pores the homogenous\nnucleation process of bulk water at 235 K does not occur and the liquid can be\nsupercooled down to at least 160 K. The analysis of SANS data allows us to\ndetermine the absolute value of the density of D2O as a function of\ntemperature. We observe a density minimum at 210+-5 K with a value of\n1.041+-0.003 g/cm3. We show that the results are consistent with the\npredictions of molecular dynamics simulations of supercooled bulk water. This\nis the first experimental report of the existence of the density minimum in\nsupercooled water.",
        "positive": "Dynamics of active particles with translational and rotational inertia: Inertial effects affecting both the translational and rotational dynamics are\ninherent to a broad range of active systems at the macroscopic scale. Thus,\nthere is a pivotal need for proper models in the framework of active matter to\ncorrectly reproduce experimental results, hopefully achieving theoretical\ninsights. For this purpose, we propose an inertial version of the active\nOrnstein-Uhlenbeck particle (AOUP) model accounting for particle mass\n(translational inertia) as well as its moment of inertia (rotational inertia)\nand derive the full expression for its steady-state properties. The inertial\nAOUP dynamics introduced in this paper is designed to capture the basic\nfeatures of the well-established inertial active Brownian particle (ABP) model,\ni.e., the persistence time of the active motion and the long-time diffusion\ncoefficient. For a small or moderate rotational inertia, these two models\npredict similar dynamics at all timescales and, in general, our inertial AOUP\nmodel consistently yields the same trend upon changing the moment of inertia\nfor various dynamical correlation functions."
    },
    {
        "anchor": "Lift force on an asymmetrical obstacle immersed in a dilute granular\n  flow: This paper investigates the lift force exerted on an elliptical obstacle\nimmersed in a granular flow through analytical calculations and computer\nsimulations. The results are shown as a function of the obstacle size,\norientation with respect to the flow direction (tilt angle), the restitution\ncoefficient and ellipse eccentricity. The theoretical argument, based on the\nforce exerted on the obstacle due to inelastic, frictionless collisions of a\nvery dilute flow, captures the qualitative features of the lift, but fails to\nreproduce the data quantitatively. The reason behind this disagreement is that\nthe dilute flow assumption on which this argument is built breaks down as a\ngranular shock wave forms in front of the obstacle. More specifically, the\nshock wave change the grains impact velocity at the obstacle, decreasing the\noverall net lift obtained from a very dilute flow.",
        "positive": "Nonlinear response theory for Markov processes III: Stochastic models\n  for dipole reorientations: The nonlinear response of molecular systems undergoing Markovian stochastic\nreorientations is calculated up to fifth order in the amplitude of the external\nfield. Time-dependent perturbation theory is used to compute the relevant\nresponse functions as in earlier treatments (G. Diezemann, Phys. Rev. E{\\bf\n85}, 051502 (2012), Phys. Rev. E{\\bf 96}, 022150 (2017)). Here, we consider the\nreorientational motion of isolated molecules and extend the existing\ncalculations for the model of isotropic rotational diffusion to the model of\nanisotropic rotational diffusion and to the model of rotational random jumps.\nDepending on the values of some model parameters, we observe a hump in the\nmodulus of the nonlinear susceptibility for either of these models.\nInterestingly, for the model of rotational random jumps, the appearance of this\nhump depends on the way the coupling to the external field is modelled in the\nmaster equation approach. If the model of anisotropic rotational diffusion is\nconsidered, the orientation of the diffusion tensor relative to the molecular\ndipole moment and additionally the amount of anisotropy in the rotational\ndiffusion constants determine the detailed shape of the nonlinear response. In\nthis case, the height of the observed hump is found to increase with increasing\n'diffusional anisotropy'. We discuss our results in relation to the features\nobserved experimentally in supercooled liquids."
    },
    {
        "anchor": "An intrinsic route to melt fracture in polymer extrusion: a weakly\n  nonlinear subcritical instability of viscoelastic Poiseuille flow: As is well known, the extrusion rate of polymers from a cylindrical tube or\nslit (a ``die'') is in practice limited by the appearance of ``melt fracture''\ninstabilities which give rise to unwanted distortions or even fracture of the\nextrudate. We present the results of a weakly nonlinear analysis which gives\nevidence for an intrinsic generic route to melt fracture via a weakly nonlinear\nsubcritical instability of viscoelastic Poiseuille flow. This instability and\nthe onset of associated melt fracture phenomena appear at a fixed ratio of the\nelastic stresses to viscous stresses of the polymer solutionte",
        "positive": "A Navier Stokes Phase Field Crystal Model for Colloidal Suspensions: We develop a fully continuous model for colloidal suspensions with\nhydrodynamic interactions. The Navier Stokes Phase Field Crystal (NS-PFC) model\ncombines ideas of dynamic density functional theory with particulate flow\napproaches and is derived in detail and related to other dynamic density\nfunctional theory approaches with hydrodynamic interactions. The derived system\nis numerically solved using adaptive finite elements and used to analyse\ncolloidal crystallization in flowing environments demonstrating a strong\ncoupling in both directions between the crystal shape and the flow field. We\nfurther validate the model against other computational approaches for\nparticulate flow systems for various colloidal sedimentation problems."
    },
    {
        "anchor": "Partial osmotic pressures of ions in electrolyte solutions: The concept of the partial osmotic pressure of ions in an electrolyte\nsolution is critically examined. In principle these can be defined by\nintroducing a solvent-permeable wall and measuring the force per unit area\nwhich can certainly be attributed to individual ions. Here I demonstrate that\nalthough the total wall force balances the bulk osmotic pressure as required by\nmechanical equilibrium, the individual partial osmotic pressures are\nextra-thermodynamic quantities dependent on the electrical structure at the\nwall, and as such they resemble attempts to define individual ion activity\ncoefficients. The limiting case where the wall is a barrier to only one species\nof ion is also considered, and with ions on both sides the classic Gibbs-Donnan\nmembrane equilibrium is recovered thus providing a unifying treatment. The\nanalysis can be extended to illustrate how the electrical state of the bulk is\naffected by the nature of the walls and the sample handling history, thus\nsupporting the 'Gibbs-Guggenheim uncertainty principle' (the notion that the\nelectrical state is unmeasurable and usually accidentally determined). Since\nthis uncertainty is conferred also onto individual ion activities, it has\nimplications for the current (2002) IUPAC definition of pH.",
        "positive": "Dissipative particle dynamics: systematic parametrization using\n  water-octanol partition coefficients: We present a systematic, top-down, thermodynamic parametrization scheme for\ndissipative particle dynamics (DPD) using water-octanol partition coefficients,\nsupplemented by water-octanol phase equilibria and pure liquid phase density\ndata. We demonstrate the feasibility of computing the required partition\ncoefficients in DPD using brute-force simulation, within an adaptive\nsemi-automatic staged optimization scheme. We test the methodology by fitting\nto experimental partition coefficient data for twenty one small molecules in\nfive classes comprising alcohols and poly-alcohols, amines, ethers and simple\naromatics, and alkanes (i.e. hexane). Finally, we illustrate the\ntransferability of a subset of the determined parameters by calculating the\ncritical micelle concentrations of selected alkyl ethoxylate surfactants, in\ngood agreement with reported experimental values."
    },
    {
        "anchor": "Direct measurement of yield stress of discrete materials: We present a novel computational method for direct measurement of yield\nstress of discrete materials. The method is well-suited for the measurement of\njamming phase diagram of a wide range of discrete particle systems such as\ngranular materials, foams, and colloids. We further successfully apply the\nmethod to evaluate the jamming phase diagram of wet granular material in order\nto demonstrates the applicability of the model.",
        "positive": "Comment on \"Flocking without Alignment Interactions in Attractive Active\n  Brownian Particles [arXiv:2303.07746]\": In a recent Letter, Caprini and L\\\"owen argue that attractive active Brownian\nparticles can flock even in the absence of explicit aligning interactions of\ntheir velocities. In this comment, I show that the phenomenology described in\n[Phys. Rev. Lett. {\\bf 130}, 148202 (2023)] in fact lacks several defining\nfeatures of flocking, such as long-range correlations and large-scale directed\nmotion."
    },
    {
        "anchor": "Collective motion of macroscopic spheres floating on capillary ripples:\n  Dynamic heterogeneity and dynamic criticality: When a dense monolayer of macroscopic slightly polydisperse spheres floats on\nchaotic capillary Faraday waves, a coexistence of large scale convective motion\nand caging dynamics typical for jammed systems is observed. We subtract the\nconvective mean flow using a coarse graining and reveal subdiffusion for the\ncaging time scales followed by a diffusive regime at later times. To test the\nsystem in the light of dynamic criticality, we apply the methods of dynamic\nheterogeneity to obtain the power-law divergent time and length scales as the\nfloater concentration approaches the jamming point. We find that these are\nindependent of the application of the coarse graining procedure. The critical\nexponents are consistent with those found in dense suspensions of colloids\nindicating universal stochastic dynamics.",
        "positive": "Direct reconstruction of the two-dimensional pair distribution function\n  in systems with angular correlations: An x-ray scattering approach to determine the two-dimensional (2D) pair\ndistribution function (PDF) in partially ordered 2D systems is proposed. We\nderive relations between the structure factor and PDF that enable quantitative\nstudies of positional and bond-orientational (BO) order in real space. We apply\nthis approach in the x-ray study of a liquid crystal (LC) film undergoing the\nsmectic-hexatic phase transition, to analyze the interplay between the\npositional and BO order during the temperature evolution of the LC film. We\nanalyze the positional correlation length in different directions in real\nspace."
    },
    {
        "anchor": "Nonlinear modes disentangle glassy and Goldstone modes in structural\n  glasses: One outstanding problem in the physics of glassy solids is understanding the\nstatistics and properties of the low-energy excitations that stem from the\ndisorder that characterizes these systems' microstructure. In this work we\nintroduce a family of algebraic equations whose solutions represent collective\ndisplacement directions (modes) in the multi-dimensional configuration space of\na structural glass. We explain why solutions of the algebraic equations, coined\nnonlinear glassy modes, are quasi-localized low-energy excitations. We present\nan iterative method to solve the algebraic equations, and use it to study the\nenergetic and structural properties of a selected subset of their solutions\nconstructed by starting from a normal mode analysis of the potential energy of\na model glass. Our key result is that the structure and energies associated\nwith harmonic glassy vibrational modes and their nonlinear counterparts\nconverge in the limit of very low frequencies. As nonlinear modes never suffer\nhybridizations, our result implies that the presented theoretical framework\nconstitutes a robust alternative definition of `soft glassy modes' in the\nthermodynamic limit, in which Goldstone modes overwhelm and destroy the\nidentity of low-frequency harmonic glassy modes.",
        "positive": "Scaling exponents of star polymers: We review recent results of the field theoretical renormalization group\nanalysis on the scaling properties of star polymers. We give a brief account of\nhow the numerical values of the exponents governing the scaling of star\npolymers were obtained as well as provide some examples of the phenomena\ngoverned by these exponents. In particular we treat the interaction between\nstar polymers in a good solvent, the Brownian motion near absorbing polymers,\nand diffusion-controlled reactions involving polymers."
    },
    {
        "anchor": "The effect of a nucleating agent on lamellar growth in\n  melt-crystallizing polyethylene oxide: The effects of a (non co-crystallizing) nucleating agent on secondary\nnucleation rate and final lamellar thickness in isothermally melt-crystallizing\npolyethylene oxide are considered. SAXS reveals that lamellae formed in\nnucleated samples are thinner than in the pure samples crystallized at the same\nundercoolings. These results are in quantitative agreement with growth rate\ndata obtained by calorimetry, and are interpreted as the effect of a local\ndecrease of the basal surface tension, determined mainly by the nucleant\nmolecules diffused out of the regions being about to crystallize. Quantitative\nagreement with a simple lattice model allows for some interpretation of the\nmechanism.",
        "positive": "E. coli \"super-contaminates\" narrow ducts fostered by broad run-time\n  distribution: One striking feature of bacterial motion is their ability to swim upstream\nalong corners and crevices, by leveraging hydrodynamic interactions. This\nmotion through anatomic ducts or medical devices might be at the origin of\nserious infections. However, it remains unclear how bacteria can maintain\npersistent upstream motion while exhibiting run-and-tumble dynamics. Here we\ndemonstrate that E. coli can travel upstream in microfluidic devices over\ndistances of 15 millimeters in times as short as 15 minutes. Using a stochastic\nmodel relating the run times to the time bacteria spend on surfaces, we\nquantitatively reproduce the evolution of the contamination profiles when\nconsidering a broad distribution of run times. Interestingly, the experimental\ndata cannot be reproduced using the usually accepted exponential distribution\nof run times. Our study demonstrates that the run-and-tumble statistics\ndetermine macroscopic bacterial transport properties. This effect, that we name\n\"super-contamination\", could explain the fast onset of some life-threatening\nmedical emergencies."
    },
    {
        "anchor": "Anomalous dynamics of an elastic membrane in an active fluid: Using numerical simulations, we characterized the behavior of an elastic\nmembrane immersed in an active fluid. Our findings reveal a nontrivial folding\nand re-expansion of the membrane that is controlled by the interplay of its\nresistance to bending and the self-propulsion strength of the active components\nin solution. We show how flexible membranes tend to collapse into multi-folded\nstates, whereas stiff membranes oscillates between an extended configuration\nand a singly folded state. This study provides a simple example of how to\nexploit the random motion of active particles to perform mechanical work at the\nmicro-scale.",
        "positive": "Hydrodynamic anomalies in supercritical fluid: Using the molecular dynamics simulations we investigate properties of\nvelocity autocorrelation function of Lennard-Jones fluid at long and\nintermediate time scales in wide ranges of temperature and density. We show\nthat the amplitudes of the leading and subleading VAF time asymptotes, $a_1$\nand $a_2$, show essentially non monotonous temperature and density dependence.\nThere are two lines on temperature-density plain corresponding to maxima of\n$a_1$ ($a_2$) along isochors and isotherms situated in the supercritical fluid\n(hydrodynamic anomalies). These lines give insight into the stages of the fluid\nevolution into gas."
    },
    {
        "anchor": "Cross-linker effect on solute adsorption in swollen thermoresponsive\n  polymer networks: The selective solute partitioning within a polymeric network is of key\nimportance to applications in which controlled release or uptake of solutes in\na responsive hydrogel is required. In this work we investigate the impact of\ncross-links on solute adsorption in a swollen polymer network by means of\nall-atom, explicit-water molecular dynamics simulations. We focus on a\nrepresentative network subunit consisting of poly($N$-isopropylacrylamide)\n(PNIPAM) and $N$,$N'$-methylenebisacrylamide (BIS/MBA) cross-linker types. Our\nstudied system consists of one BIS-linker with four atactic PNIPAM chains\nattached in a tetrahedral geometry. The adsorption of several representative\nsolutes of different polarity in the low concentration limit at the linker\nregion is examined. We subdivide the solute adsorption regions and distinguish\nbetween contributions stemming from polymer chains and cross-link parts. In\ncomparison to a single polymer chain, we observe that the adsorption of the\nsolutes to the cross-link region can significantly differ, with details\ndepending on the specific compounds' size and polarity. In particular, for\nsolutes that have already a relatively large affinity to PNIPAM chains the\ndense cross-link region (where many-body attractions are at play) amplifies the\nlocal adsorption by an order of magnitude. We also find that the cross-link\nregion can serve as a seed for the aggregation of mutually attractive solutes\nat higher solute concentrations. Utilizing the microscopic adsorption\ncoefficients in a mean-field model of an idealized macroscopic polymer network,\nwe extrapolate these results to the global solute partitioning in a swollen\nhydrogel and predict that these adsorption features may lead to non-monotonic\npartition ratios as a function of the cross-link density.",
        "positive": "Measurement of surface deformation and cohesion of a granular pile under\n  the effect of centrifugal force: An experimental apparatus measuring free-surface deformation of a centrifuged\ngranular pile is developed. By horizontally rotating a quasi two-dimensional\ngranular pile whose apex is located at the vertical rotation axis, the\nresultant force of gravity and centrifuge yields the deformation of the\ngranular pile. In this setup, centrifugal force depends on distance from the\nrotation axis whilst gravitational force is constant everywhere. Therefore,\nfree-surface deformation by various centrifuge degrees can be systematically\nexamined using this apparatus. In the system, a small unit consisting of a\ncamera and computer is rotated with the granular sample to record the\nrotation-induced deformation. To evaluate the validity of the system,\ndeformation of a rotated water surface is first measured and analyzed. The\nobtained data are properly explained by the theoretical parabolas without any\nfitting parameter. Next, we measure the deformation of non-cohesive and\ncohesive granular piles using the developed apparatus. Both granular samples\nshow the significant deformation of granular pile and finally develop steep\ngranular slopes on the side walls. However, details of the deformation\nprocesses depend on the cohesion strength. To quantitatively characterize the\ndifference, the effective strength by cohesion and granular local-slope\nvariations are analyzed based on the experimental results."
    },
    {
        "anchor": "Wedge covariance for 2D filling and wetting: A comprehensive theory of interfacial fluctuation effects occurring at 2D\nwedge (corner) filling transitions in pure (thermal disorder) and impure\n(random bond-disorder) systems is presented. Scaling theory and the explicit\nresults of transfer matrix and replica trick studies of interfacial Hamiltonian\nmodels reveal that, for almost all examples of intermolecular forces, the\ncritical behaviour at filling is fluctuation-dominated, characterised by\nuniversal critical exponents and scaling functions that depend only on the\nwandering exponent $\\zeta$. Within this filling fluctuation (FFL) regime, the\ncritical behaviour of the mid-point interfacial height, probability\ndistribution function, local compressibility and wedge free energy are\nidentical to corresponding quantities predicted for the strong-fluctuation\n(SFL) regime for critical wetting transitions at planar walls. In particular\nthe wedge free energy is related to the SFL regime point tension which is\ncalculated for systems with random-bond disorder using the replica trick. The\nconnection with the SFL regime for all these quantities can be expressed\nprecisely in terms of special wedge covariance relations which complement\nstandard scaling theory and restrict the allowed values of the critical\nexponents for both FFL filling and SFL critical wetting.",
        "positive": "Protein Folding as a Physical Stochastic Process: We model protein folding as a physical stochastic process as follows. The\nunfolded protein chain is treated as a random coil described by SAW\n(self-avoiding walk). Folding is induced by hydrophobic forces and other\ninteractions, such as hydrogen bonding, which can be taken into account by\nimposing conditions on SAW. The resulting model is termed CSAW (conditioned\nself-avoiding walk. Conceptually, the mathematical basis is a generalized\nLangevin equation. In practice, the model is implemented on a computer by\ncombining SAW and Monte Carlo. To illustrate the flexibility and capabilities\nof the model, we consider a number of examples, including folding pathways,\nelastic properties, helix formation, and collective modes."
    },
    {
        "anchor": "The induced permittivity increment of electrorheological fluids in an\n  applied electric field in association with chain formation: A Brownian\n  Dynamics simulation study: We report Brownian Dynamics simulation results for the relative permittivity\nof electrorheological (ER) fluids in an applied electric field. The relative\npermittivity of an ER fluid can be calculated from the Clausius-Mosotti (CM)\nequation in the small applied field limit. When a strong field is applied,\nhowever, the ER spheres are organized into chains and assemblies of chains in\nwhich case the ER spheres are polarized not only by the external field but by\neach other. This manifests itself in an enhanced dielectric response, e.g., in\nan increase in the relative permittivity. The correction to the relative\npermittivity and the time dependence of this correction is simulated on the\nbasis of a model in which the ER particles are represented as polarizable\nspheres. In this model, the spheres are also polarized by each other in\naddition to the applied field. Our results are qualitatively similar to those\nobtained by Horv\\'ath and Szalai experimentally (\\textit{Phys. Rev. E},\n\\textbf{86}, 061403, 2012). We report characteristic time constants obtained\nfrom bi-exponential fits that can be associated with formation of pairs and\nshort chains as well as with aggregation of chains. The electric field\ndependence of the induced dielectric increment reveals the same qualitative\nbehavior that experiments did: three regions with different slopes\ncorresponding to different aggregation processes are identified.",
        "positive": "A Simulation Algorithm for Brownian Dynamics on Complex Curved Surfaces: Brownian dynamics of colloidal particles on complex surfaces has found\nimportant applications in diverse physical, chemical and biological processes.\nHowever, current Brownian dynamics simulation algorithms mostly work for\nrelatively simple surfaces that can be analytically parameterized. In this\nwork, we develop an algorithm to enable Brownian dynamics simulation on\nextremely complex surfaces. We approximate complex surfaces with triangle mesh\nsurfaces and employ a novel scheme to perform particle simulation on these\ntriangle mesh surfaces. Our algorithm computes forces and velocities of\nparticles in global coordinates but updates their positions in local\ncoordinates, which benefits from the advantages of simulation schemes in both\nglobal and local coordinate alone. We benchmark the proposed algorithm with\ntheory and then simulate Brownian dynamics of both single and multiple\nparticles on torus and knot surfaces. The results show that our method captures\nwell diffusion, transport, and crystallization of colloidal particles on\ncomplex surfaces with non-trivial topology. This study offers an efficient\nstrategy for elucidating the impact of curvature, geometry, and topology on\nparticle dynamics and microstructure formation in complex environments."
    },
    {
        "anchor": "One- and two-particle microrheology: We study the dynamics of rigid spheres embedded in viscoelastic media and\naddress two questions of importance to microrheology. First we calculate the\ncomplete response to an external force of a single bead in a homogeneous\nelastic network viscously coupled to an incompressible fluid. From this\nresponse function we find the frequency range where the standard assumptions of\nmicrorheology are valid. Second we study fluctuations when embedded spheres\nperturb the media around them and show that mutual fluctuations of two\nseparated spheres provide a more accurate determination of the complex shear\nmodulus than do the fluctuations of a single sphere.",
        "positive": "Nonlinear buckling and symmetry breaking of a soft elastic sheet sliding\n  on a cylindrical substrate: We consider the axial compression of a thin sheet wrapped around a rigid\ncylindrical substrate. In contrast to the wrinkling-to-fold transitions\nexhibited in similar systems, we find that the sheet always buckles into a\nsingle symmetric fold, while periodic solutions are unstable. Upon further\ncompression, the solution breaks symmetry and stabilizes into a recumbent fold.\nUsing linear analysis and numerics, we theoretically predict the buckling force\nand energy as a function of the compressive displacement. We compare our theory\nto experiments employing cylindrical neoprene sheets and find remarkably good\nagreement."
    },
    {
        "anchor": "The Hydrodynamic Interaction in Polymer Solutions Simulated with\n  Dissipative Particle Dynamics: We analyzed extensively the dynamics of polymer chains in solutions simulated\nwith dissipative particle dynamics (DPD), with a special focus on the potential\ninfluence of a low Schmidt number of a typical DPD fluid on the simulated\npolymer dynamics. It has been argued that a low Schmidt number in a DPD fluid\ncan lead to underdevelopment of the hydrodynamic interaction in polymer\nsolutions. Our analyses reveal that equilibrium polymer dynamics in dilute\nsolution, under a typical DPD simulation conditions, obey the Zimm model very\nwell. With a further reduction in the Schmidt number, a deviation from the Zimm\nmodel to the Rouse model is observed. This implies that the hydrodynamic\ninteraction between monomers is reasonably developed under typical conditions\nof a DPD simulation. Only when the Schmidt number is further reduced, the\nhydrodynamic interaction within the chains becomes underdeveloped. The\nscreening of the hydrodynamic interaction and the excluded volume interaction\nas the polymer volume fraction is increased are well reproduced by the DPD\nsimulations. The use of soft interaction between polymer beads and a low\nSchmidt number do not produce noticeable problems for the simulated dynamics at\nhigh concentrations, except that the entanglement effect which is not captured\nin the simulations.",
        "positive": "Wrinkling of soft magneto-active plates: Coupled magneto-mechanical wrinkling has appeared in many scenarios of\nengineering and biology. Hence, soft magneto-active (SMA) plates buckle when\nsubject to critical uniform magnetic field normal to their wide surface. Here,\nwe provide a systematic analysis of the wrinkling of SMA plates subject to an\nin-plane mechanical load and a transverse magnetic field?. We consider two\nloading modes: plane-strain loading and uni-axial loading, and two models of\nmagneto-sensitive plates: the neo-Hookean ideal magneto-elastic model and the\nneo-Hookean magnetization saturation Langevin model. Our analysis relies on the\ntheory of nonlinear magneto-elasticity and the associated linearized theory for\nsuperimposed perturbations. We derive the Stroh formulation of the governing\nequations of wrinkling, and combine it with the surface impedance method to\nobtain explicitly the bifurcation equations identifying the onset of symmetric\nand antisymmetric wrinkles. We also obtain analytical expressions of\ninstability in the thin- and thick-plate limits. For thin plates, we make the\nlink with classical Euler buckling solutions. We also perform an exhaustive\nnumerical analysis to elucidate the effects of loading mode, load amplitude,\nand saturation magnetization on the nonlinear static response and bifurcation\ndiagrams. We find that antisymmetric wrinkling modes always occur before\nsymmetric modes. Increasing the pre-compression or heightening the magnetic\nfield has a destabilizing effect for SMA plates, while the saturation\nmagnetization enhances their stability. We show that the Euler buckling\nsolutions are a good approximation to the exact bifurcation curves for thin\nplates."
    },
    {
        "anchor": "Designed Interaction Potentials via Inverse Methods for Self-Assembly: We formulate statistical-mechanical inverse methods in order to determine\noptimized interparticle interactions that spontaneously produce target\nmany-particle configurations. Motivated by advances that give experimentalists\ngreater and greater control over colloidal interaction potentials, we propose\nand discuss two computational algorithms that search for optimal potentials for\nself-assembly of a given target configuration. The first optimizes the\npotential near the ground state and the second near the melting point. We begin\nby applying these techniques to assembling open structures in two dimensions\n(square and honeycomb lattices) using only circularly symmetric pair\ninteraction potentials ; we demonstrate that the algorithms do indeed cause\nself-assembly of the target lattice. Our approach is distinguished from\nprevious work in that we consider (i) lattice sums, (ii) mechanical stability\n(phonon spectra), and (iii) annealed Monte Carlo simulations. We also devise\ncircularly symmetric potentials that yield chain-like structures as well as\nsystems of clusters.",
        "positive": "A Model for Transits in Dynamic Response Theory: The first goal of Vibration-Transit (V-T) theory was to construct a tractable\napproximate Hamiltonian from which the equilibrium thermodynamic properties of\nmonatomic liquids can be calculated. The Hamiltonian for vibrations in an\ninfinitely extended harmonic random valley, together with the universal\nmultiplicity of such valleys, gives an accurate first-principles account of the\nmeasured thermodynamic properties of the elemental liquids at melt. In the\npresent paper, V-T theory is extended to non-equilibrium properties, through an\napplication to the dynamic structure factor S(q,w). It was previously shown\nthat the vibrational contribution alone accurately accounts for the Brillouin\npeak dispersion curve for liquid sodium, as compared both with MD calculations\nand inelastic x-ray scattering data. Here it is argued that the major effects\nof transits will be to disrupt correlations within the normal mode vibrational\nmotion, and to provide an additional source of inelastic scattering. We\nconstruct a parameterized model for these effects, and show that it is capable\nof fitting MD results for S(q,w) in liquid sodium. A small discrepancy between\nmodel and MD at large q is attributed to multimode vibrational scattering. In\ncomparison, mode coupling theory formulates S(q,w) in terms of processes\nthrough which density fluctuations decay. While mode coupling theory is also\ncapable of modeling S(q,w) very well, V-T theory is the more universal since it\nexpresses all statistical averages, thermodynamic functions and time\ncorrelation functions alike, in terms of the same motional constituents,\nvibrations and transits."
    },
    {
        "anchor": "Convergent resummed linear delta expansion in the critical O(N)\n  (\u03c6_i^2)^2_{3d} model: The nonperturbative linear delta expansion (LDE) method is applied to the\ncritical O(N) phi^4 three-dimensional field theory which has been widely used\nto study the critical temperature of condensation of dilute weakly interacting\nhomogeneous Bose gases. We study the higher order convergence of the LDE as it\nis usually applied to this problem. We show how to improve both, the large-N\nand finite N=2, LDE results with an efficient resummation technique which\naccelerates convergence. In the large N limit, it reproduces the known exact\nresult within numerical integration accuracy. In the finite N=2 case, our\nimproved results support the recent numerical Monte Carlo estimates for the\ncritical transition temperature of Bose-Einstein condensation.",
        "positive": "Inertial Force Transmission in Dense Granular Flows: Dense granular flows are well described by several continuum models, however,\ntheir internal dynamics remain elusive. This study explores the contact force\ndistributions in simulated steady and homogenous shear flows. Results\ndemonstrate the existence of high magnitude contact forces in faster flows with\nstiffer grains. A proposed physical mechanism explains this rate-dependent\nforce transmission. This analysis establishes a relation between contact forces\nand grain velocities, providing an entry point to unify a range of continuum\nmodels derived from either contact forces or grain velocity."
    },
    {
        "anchor": "Controlling the folding and substrate-binding of proteins using polymer\n  brushes: The extent of coupling between the folding of a protein and its binding to a\nsubstrate varies from protein to protein. Some proteins have highly structured\nnative states in solution, while others are natively disordered and only fold\nfully upon binding. In this Letter, we use Monte Carlo simulations to\ninvestigate how disordered polymer chains grafted around a binding site affect\nthe folding and binding of three model proteins. The protein that approaches\nthe substrate fully folded is more hindered during the binding process than\nthose whose folding and binding are cooperative. The polymer chains act as\nlocalized crowding agents and can select correctly folded and bound\nconfigurations in favor of non-specifically adsorbed states. The free energy\nchange for forming all intra-protein and protein-substrate contacts can depend\nnon-monotonically on the polymer length.",
        "positive": "Pattern Competition in the Photorefractive Semiconductors: We analytically study the photorefractive Gunn effect in n-GaAs subjected to\ntwo external laser beams which form a moving interference pattern (MIP) in the\nsemiconductor. When the intensity of the spatially independent part of the MIP,\ndenoted by $I_0$, is small, the system has a periodic domain train (PDT),\nconsistent with the results of linear stability analysis. When $I_0$ is large,\nthe space-charge field induced by the MIP will compete with the PDT and result\nin complex dynamics, including driven chaos via quasiperiodic route."
    },
    {
        "anchor": "Design of eco-friendly fabric softeners: structure, rheology and\n  interaction with cellulose nanocrystals: Concentrated fabric softeners are water-based formulations containing around\n10 - 15 wt. % of double tailed esterquat surfactants primarily synthesized from\npalm oil. In recent patents, it was shown that a significant part of the\nsurfactant contained in today formulations can be reduced by circa 50 % and\nreplaced by natural guar polymers without detrimental effects on the deposition\nand softening performances. We presently study the structure and rheology of\nthese softener formulations and identify the mechanisms at the origin of these\neffects.\n  The polymer additives used are guar gum polysaccharides, one cationic and one\nmodified through addition of hydroxypropyl groups. Formulations with and\nwithout guar polymers are investigated using optical and cryo-transmission\nelectron microscopy, small-angle light and Xray scattering and finally\nrheology. Similar techniques are applied to study the phase behavior of\nsoftener and cellulose nanocrystals considered here as a model for cotton.\n  The esterquat surfactants are shown to assemble into micron-sized vesicles in\nthe dilute and concentrated regimes. In the former, guar addition in small\namounts does not impair the vesicular structure and stability. In the\nconcentrated regime, cationic guars induce a local crowding associated to\ndepletion interactions and leads to the formation of a local lamellar order. In\nrheology, adjusting the polymer concentration at one tenth that of the\nsurfactant is sufficient to offset the decrease of the elastic property\nassociated with the surfactant reduction. In conclusion, we have shown that\nthrough an appropriate choice of natural additives it is possible to lower the\nconcentration of surfactants in fabric conditioners by about half, a result\nthat could represent a significant breakthrough in current home care\nformulations.",
        "positive": "Molecular aggregation in liquid water: Laplace spectra and spectral\n  clustering of H-bonded network: Application of the spectral clustering method based on the analyses of the\nLaplace matrix is an acceptable indicator of the global properties of H-bonded\nnetwork. The first peak of the Laplace spectra contains six eigenvalues. These\nresults suggest that six communities are always formed in our simulated systems\nindependently of the number of molecules in the cubic box. We showed that the\nH-bonded environment on the surface of the clusters is different from what can\nbe found inside of the clusters. The fraction of four-coordinated molecules is\nsignificantly larger in the case of surface molecules. Our work emphasizes that\nthe periodic boundary conditions always cause clustering in the system."
    },
    {
        "anchor": "Chiral tilt texture domains in two dimensions: We study the shape and texture of finite domains comprising chiral/achiral\nmolecules carrying a tilt field embedded in a 2-dimensional surface. Using a\ncombination of simulations and {\\it exact} variational calculations, we\ndetermine the equilibrium (mean field) phase diagram in the achiral and chiral\ncases. We find a variety of novel shapes and textures including a {\\it\nspontaneously broken chiral texture} when the molecules are achiral. We show\nthat chiral tilt-domains nucleating in a region of two-phase coexistence, {\\it\nrepel} each other, thereby preventing coalescence and further growth. Our work\nhas implications for tilt texture domains in phospholipid monolayers and giant\nunilamellar vesicles (GUVs), nucleating domains of Sm-C$^*$ in Sm-A films, and\nchiral emulsions in Sm-A films.",
        "positive": "Electrochemistry meets polymer physics: polymerized ionic liquids on an\n  electrified electrode: Polymeric ionic liquids are emerging polyelectrolyte materials for modern\nelectrochemical applications. In this paper, we propose a self-consistent field\ntheory of the polymeric ionic liquid on a charged conductive electrode. Taking\ninto account the conformation entropy of rather long polymerized cations within\nthe Lifshitz theory and electrostatic and excluded volume interactions of ionic\nspecies within the mean-field approximation, we obtain a system of\nself-consistent field equations for the local electrostatic potential and\naverage concentrations of monomeric units and counterions. We solve these\nequations in the linear approximation for the cases of a point-like charge and\na flat infinite uniformly charged electrode immersed in a polymeric ionic\nliquid and derive analytical expressions for local ionic concentrations and\nelectrostatic potential, and derive an analytical expression for the linear\ndifferential capacitance of the electric double layer. We also find a numerical\nsolution to the self-consistent field equations for two types of boundary\nconditions for the local polymer concentration on the electrode, corresponding\nto the cases of the specific adsorption absence (indifferent surface) and\nstrong short-range repulsion of the monomeric units near the charged surface\n(hard wall case). For both cases, we investigate the behavior of differential\ncapacitance as a function of applied voltage for a pure polymeric ionic liquid\nand a polymeric ionic liquid dissolved in a polar organic solvent. We observe\nthat the differential capacitance profile shape is strongly sensitive to the\nadopted boundary condition for the local polymer concentration on the\nelectrode."
    },
    {
        "anchor": "Universality of breath figures on two-dimensional surfaces: an\n  experimental study: Droplet condensation on surfaces produces patterns, called breath figures.\nTheir evolution into self-similar structures is a classical example of\nself-organization. It is described by a scaling theory with scaling functions\nwhose universality has recently been challenged by numerical work. Here, we\nprovide a thorough experimental testing, where we inspect substrates with\nvastly different chemical properties, stiffness, and condensation rates. We\ncritically survey the size distributions, and the related time-asymptotic\nscaling of droplet number and surface coverage. In the time-asymptotic regime\nthey admit a data collapse: the data for all substrates and condensation rates\nlie on universal scaling functions.",
        "positive": "Hyperuniformity in deterministic anti-aligning active matter: We highlight the importance of long-range correlations in active matter\nsystems of dilute self-propelling particles even in the absence of global order\nby demonstrating that long-range density fluctuations are suppressed. We show\nthis analytically for a one-dimensional lattice process employing Poisson\nrepresentation. Numerically, we corroborate the relevance of these findings for\noff-lattice Vicsek-type models with anti-aligning interactions."
    },
    {
        "anchor": "Threading-Induced Dynamical Transition in Tadpole-Shaped Polymers: The relationship between polymer topology and bulk rheology remains a key\nquestion in soft matter physics. Architecture-specific constraints (or\nthreadings) are thought to control the dynamics of ring polymers in ring-linear\nblends, which thus affects the viscosity to range between that of the pure\nrings and a value larger, but still comparable to, that of the pure linear\nmelt. Here we consider qualitatively different systems of linear and ring\npolymers, fused together in \"chimeric\" architectures. The simplest example of\nthis family is a \"tadpole\"-shaped polymer - a single ring fused to the end of a\nsingle linear chain. We show that polymers with this architecture display a\nthreading-induced dynamical transition that substantially slows chain\nrelaxation. Our findings shed light on how threadings control dynamics and may\ninform design principles for chimeric polymers with topologically-tunable bulk\nrheological properties.",
        "positive": "Static and dynamic properties of a particle-based algorithm for\n  non-ideal fluids and binary mixtures: A recently introduced particle-based model for fluid dynamics with effective\nexcluded volume interactions is analyzed in detail. The interactions are\nmodeled by means of stochastic multiparticle collisions which are biased and\ndepend on local velocities and densities. Momentum and energy are exactly\nconserved locally. The isotropy and relaxation to equilibrium are analyzed and\nmeasured. It is shown how a discrete-time projection operator technique can be\nused to obtain Green-Kubo relations for the transport coefficients. Because of\na large viscosity no long-time tails in the velocity auto-correlation and\nstress correlation functions were seen. Strongly reduced self-diffusion due to\ncaging and an order/disorder transition is found at high collision frequency,\nwhere clouds consisting of at least four particles form a cubic phase. These\nstructures were analyzed by measuring the pair-correlation function above and\nbelow the transition. Finally, the algorithm is extended to binary mixtures\nwhich phase-separate above a critical collision rate."
    },
    {
        "anchor": "Melting a granular glass by cooling: Driven granular systems readily form glassy phases at high particle volume\nfractions and low driving amplitudes. We use computer simulations of a driven\ngranular glass to evidence a re-entrance melting transition into a fluid state,\nwhich, contrary to intuition, occurs by \\emph{reducing} the amplitude of the\ndriving. This transition is accompanied by anomalous particle dynamics and\nsuper-diffusive behavior on intermediate time-scales. We highlight the special\nrole played by frictional interactions, which help particles to escape their\nglassy cages. Such an effect is in striking contrast to what friction is\nexpected to do: reduce particle mobility by making them stick.",
        "positive": "Phase Separation and Aggregation in Multiblock Chains: This article focuses on phase and aggregation behavior for linear chains\ncomposed of blocks of hydrophilic and hydrophobic segments. Phase and\nconformational transitions of patterned chains are relevant for understanding\nliquid-liquid separation of biomolecular condensates, which play a prominent\nrole in cellular biophysics, but also for surfactant and polymer applications.\nPrevious studies of simple models for multiblock chains have shown that,\ndepending on the sequence pattern and chain length, such systems can fall into\none of two categories: displaying either phase separation or aggregation into\nfinite-size clusters. The key new result of the present study is that both\nformation of finite-size aggregates and phase separation can be observed for\ncertain chain architectures at appropriate conditions of temperature and\nconcentration. For such systems, a bulk dense liquid condenses from a dilute\nphase that already contains multi-chain finite-size aggregates. The\ncomputational approach involves several distinct steps using\nhistogram-reweighting grand canonical Monte Carlo simulations, which are\ndescribed here in some level of detail."
    },
    {
        "anchor": "Imprinted Networks as Chiral Pumps: We investigate the interaction between a chirally imprinted network and a\nsolvent of chiral molecules. We find, a liquid crystalline polymer network is\npreferentially swollen by one component of a racemic solvent. This ability to\nseparate is linked to the chiral order parameter of the network, and can be\nreversibly controlled via temperature or a mechanical deformation. It is\nmaximal near the point at which the network loses its imprinted structure. One\npossible practical application of this effect would be a mechanical device for\nsorting mixed chiral molecules.",
        "positive": "Self-organized dynamics and the transition to turbulence of confined\n  active nematics: We study how confinement transforms the chaotic dynamics of bulk\nmicrotubule-based active nematics into regular spatiotemporal patterns. For\nweak confinements, multiple continuously nucleating and annihilating\ntopological defects self-organize into persistent circular flows of either\nhandedness. Increasing confinement strength leads to the emergence of distinct\ndynamics, in which the slow periodic nucleation of topological defects at the\nboundary is superimposed onto a fast procession of a pair of defects. A defect\npair migrates towards the confinement core over multiple rotation cycles, while\nthe associated nematic director field evolves from a distinct double spiral\ntowards a nearly circularly symmetric configuration. The collapse of the defect\norbits is punctuated by another boundary-localized nucleation event, that sets\nup long-term doubly-periodic dynamics. Comparing experimental data to a\ntheoretical model of an active nematic, reveals that theory captures the fast\nprocession of a pair of $+\\frac{1}{2}$ defects, but not the slow spiral\ntransformation nor the periodic nucleation of defect pairs. Theory also fails\nto predict the emergence of circular flows in the weak confinement regime. The\ndeveloped confinement methods are generalized to more complex geometries,\nproviding a robust microfluidic platform for rationally engineering\ntwo-dimensional autonomous flows."
    },
    {
        "anchor": "Efficient algorithms for the dense packing of congruent circles inside a\n  square: We study dense packings of a large number of congruent non-overlapping\ncircles inside a square by looking for configurations which maximize the\npacking density, defined as the ratio between the area occupied by the disks\nand the area of the square container. The search for these configurations is\ncarried out with the help of two algorithms that we have devised: a first\nalgorithm is in charge of obtaining sufficiently dense configurations starting\nfrom a random guess, while a second algorithm improves the configurations\nobtained in the first stage. The algorithms can be used sequentially or\nindependently. The performance of these algorithms is assessed by carrying out\nnumerical tests for configurations with a large number of circles.",
        "positive": "Effective interactions between inclusions in a chiral active bath inside\n  a channel: Colloidal inclusions suspended in a bath of smaller particles experience an\neffective bath-mediated attraction at small intersurface separations, which is\nknown as the depletion interaction. In an active bath of nonchiral\nself-propelled particles, the effective force changes from attraction to\nrepulsion; an effect that is suppressed, when the active bath particles are\nchiral. Using Brownian Dynamics simulations, we study the effects of channel\nconfinement and bath chirality on the effective forces and torques that are\nmediated between two inclusions that may be fixed within the channel or may be\nallowed to rotate freely as a rigid dimer around its center of mass. We show\nthat the confinement has a strong effect on the effective interactions,\ndepending on the orientation of the dimer relative to the channel walls. The\nactive particle chirality leads to a force imbalance and, hence, a net torque\non the inclusion dimer, which we investigate as a function of the bath\nchirality strength and the channel height."
    },
    {
        "anchor": "Buckling of stiff polymer rings in weak spherical confinement: Confinement is a versatile and well-established tool to study the properties\nof polymers either to understand biological processes or to develop new\nnano-biomaterials. We investigate the conformations of a semiflexible polymer\nring in weak spherical confinement imposed by an impenetrable shell. We develop\nan analytic argument for the dominating polymer trajectory depending on polymer\nflexibility considering elastic and entropic contributions. Monte Carlo\nsimulations are performed to assess polymer ring conformations in probability\ndensities and by the shape measures asphericity and nature of asphericity.\nComparison of the analytic argument with the mean asphericity and the mean\nnature of asphericity confirm our reasoning to explain polymer ring\nconformations in the stiff regime, where elastic response prevails.",
        "positive": "Topological and non-topological mechanisms of loops formation in\n  chromosomes: effects on the contact probability: Chromosomes are crumpled polymer chains further folded into a sequence of\nstochastic loops via loop extrusion. While extrusion has been verified\nexperimentally, the particular means by which the extruding complexes bind DNA\npolymer remains controversial. Here we analyze the behaviour of the contact\nprobability function for a crumpled polymer with loops for the two possible\nmodes of cohesin binding, topological and non-topological mechanisms. As we\nshow, in the non-topological model the chain with loops resembles a comb-like\npolymer that can be solved analytically using the quenched disorder approach.\nIn contrast, in the topological binding case the loop constraints are\nstatistically coupled due to long-range correlations present in a non-ideal\nchain, which can be described by the perturbation theory in the limit of small\nloop densities. As we show, the quantitative effect of loops on a crumpled\nchain in the case of topological binding should be stronger, which is\ntranslated into a larger amplitude of the log-derivative of the contact\nprobability. Our results highlight a physically different organization of a\ncrumpled chain with loops by the two mechanisms of loops formation."
    },
    {
        "anchor": "Exact Calculations of Membrane Areas with Simple Models: The distinction between the true total area and the projected area is\nelucidated with soluble models which represent the membrane as a self-avoiding\nstring on a plane. Constraining the total area to a predetermined value changes\nthe averages very significantly. The latter are calculated exactly from the\ngenerating functions of self-avoiding walks and are shown as functions of\nactivities $q$ and $r$ related to temperature $T=\\pm 1/\\log (q)$ and lateral\nforce $f=-\\log (r)$. The constraint makes the partition functions and averages\nvalid for all $q,r >0$ and reduces the ratio of $A_{tot}$ to the projected area\n$L$. High temperature divergences are supressed. Possible applications to\nsimulated bilayers/membranes are discussed.",
        "positive": "Hard Sphere Dynamics for Normal and Granular Fluids: A fluid of N smooth, hard spheres is considered as a model for normal\n(elastic collisions) and granular (inelastic collisions) fluids. The potential\nenergy is discontinuous for hard spheres so the pairwise forces are singular\nand the usual forms of Newtonian and Hamiltonian mechanics do not apply.\nNevertheless, particle trajectories in the N particle phase space are well\ndefined and the generators for these trajectories can be identified. The first\npart of this presentation is a review of the generators for the dynamics of\nobservables and probability densities. The new results presented in the second\npart refer to applications of these generators to the Liouville dynamics for\ngranular fluids. A set of eigenvalues and eigenfunctions of the generator for\nthis Liouville dynamics is identified in a special \"stationary representation\".\nThis provides a class of exact solutions to the Liouville equation that are\nclosely related to hydrodynamics for granular fluids."
    },
    {
        "anchor": "Hidden scale invariance in the Gay-Berne model: This paper presents a numerical study of the Gay-Berne liquid crystal model\nwith parameters corresponding to calamitic (rod-shaped) molecules. The focus is\non the isotropic and nematic phases at temperatures above unity. There we find\nstrong correlations between the virial and potential-energy thermal\nfluctuations, reflecting the hidden-scale invariance symmetry. This implies the\nexistence of isomorphs, which are curves in the thermodynamic phase diagram of\napproximately invariant physics. We study numerically one isomorph in the\nisotropic phase and one in the nematic phase. In both cases, good invariance of\nthe dynamics is demonstrated via data for the reduced-unit time-autocorrelation\nfunctions of the mean-square displacement, angular velocity, force, torque, and\nfirst- and second-order Legendre polynomial orientational order parameters.\nDeviations from isomorph invariance are observed at short times for the\norientational time-autocorrelation functions, which reflects the fact that the\nmoment of inertia is assumed to be constant and thus not isomorph invariant in\nreduced units. Structural isomorph invariance is demonstrated from data for the\nradial distribution functions of the particles and their orientations. For\ncomparison, all quantities were also simulated along an isochore of similar\ntemperature variation in which case invariance is not observed. We conclude\nthat the thermodynamic phase diagram of the calamitic Gay-Berne model is\nessentially one-dimensional in the studied regions as predicted by isomorph\ntheory, a fact that potentially allows for simplifications of future theories\nand numerical studies.",
        "positive": "Ferronematics in confinement: The behavior of a uniformly magnetized ferronematic slab is investigated\nnumerically in a situation in which an external magnetic field is applied\nparallel and antiparallel, respectively, to its initial magnetization\ndirection. The employed numerical method allows one to determine hysteresis\ncurves, from which a critical magnetic field strength (i.e., the one at which\nthe ferronematic sample becomes distorted) as function of the system parameters\ncan be inferred. Two possible mechanisms of switching the magnetization by\napplying a magnetic field in the antiparallel direction are observed and\ncharacterized in terms of the coupling constant between the magnetization and\nthe nematic director as well as in terms of the coupling strength of the\nnematic liquid crystal and the walls of the slab. Suitably prepared walls allow\none to combine both switching mechanisms in one setup, such that one can\nconstruct a cell the magnetization of which can be reversibly switched off."
    },
    {
        "anchor": "Disjoining Pressure of an Electrolyte Film Confined between\n  Semipermeable Membranes: We consider an electrolyte solution confined by semipermeable membranes in\ncontact with a salt-free solvent. Membranes are uncharged, but since small\ncounter-ions leak-out into infinite salt-free reservoirs, we observe a\ndistance-dependent membrane potential, which generates a repulsive\nelectrostatic disjoining pressure. We obtain the distribution of the potential\nand of ions, and derive explicit formulas for the disjoining pressure, which\nare validated by computer simulations. We predict a strong short-range\npower-law repulsion, and a weaker long-range exponential decay. Our results\nalso demonstrate that an interaction between membranes does strongly depend on\nthe screening lengths, valency of an electrolyte solution, and an\ninter-membrane film thickness. Finally, our analysis can be directly extended\nto the study of more complex situations and some biological problems.",
        "positive": "Freezing of a Liquid Marble: In this study, we present for the first time the observations of a freezing\nliquid marble. In the experiment, liquid marbles are gently placed on the cold\nside of a Thermo-Electric Cooler (TEC) and the morphological changes are\nrecorded and characterized thereafter. These liquid marbles are noticed to\nundergo a shape transition from a spherical to a flying-saucer shaped\nmorphology. The freezing dynamics of liquid marbles is observed to be very\ndifferent from that of a freezing water droplet on a superhydrophobic surface.\nFor example, the pointy tip appearing on a frozen water drop could not be\nobserved for a frozen liquid marble. In the end, we highlight a possible\nexplanation for the observed morphology."
    },
    {
        "anchor": "Spatial modulation of the composition of a binary liquid near a\n  repulsive wall: When a binary liquid is confined by a strongly repulsive wall, the local\ndensity is depleted near the wall and an interface similar to that between the\nliquid and its vapor is formed. This analogy suggests that the composition of\nthe binary liquid near this interface should exhibit spatial modulation similar\nto that near a liquid-vapor interface even if the interactions of the wall with\nthe two components of the liquid are the same. The Guggenheim adsorption\nrelation quantifies the concentrations of two components of a binary mixture\nnear a liquid-vapor interface and qualitatively states that the majority\n(minority) component enriches the interface for negative (positive) mixing\nenergy if the surface tensions of the two components are not very different.\nFrom molecular dynamics simulations of binary mixtures with different\ncompositions and interactions, we find that the Guggenheim relation is\nqualitatively satisfied at wall-induced interfaces for systems with negative\nmixing energy at all state points considered. For systems with positive mixing\nenergy, this relation is found to be qualitatively valid at low densities,\nwhile it is violated at state points with high density where correlations in\nthe liquid are strong. This observation is validated by a calculation of the\ndensity profiles of the two components of the mixture using density functional\ntheory with the Ramakrishnan-Yussouff free-energy functional. Possible reasons\nfor the violation of the Guggenheim relation are discussed.",
        "positive": "Conformation-Induced Stiffening Effect of Crosslinked Polymer Thin Films: Nanoscale polymeric thin films are widely used in diverse applications such\nas energy devices, flexible electronics and biosensors, where a satisfactory\nmechanical performance is of vital importance to realize their full\nfunctionality. It has been evidenced that the elastic properties of polymer\nfilms are often strongly affected by their thickness; however, the underlying\nmechanism of this phenomenon, especially a thorough understanding at the\nmicroscopic level, has yet to be achieved. Here we established a coarse-grained\nmolecular dynamics (CGMD) based computational framework, combining with\nexperimental verifications, aiming to reveal the conformational origin of the\nstiffening behavior of crosslinked polymeric thin films. By imposing systematic\ncontrols over the polymer network structures, we found that the bi-axial\nmodulus changes are essentially consequent of the alteration of polymer\nconformations. A unified theory was then proposed, to quantitatively clarify\nthe correlation between the elastic properties of the system and the\ndistributional variations of the chain end-to-end distances, with predicting a\nsignificant hardening effect on top of the conventional entropic elasticity\nwith largely uncoiled chains. Adopting processing protocols inspired by the\nmodeling, our experiments showed that PDMS films at approximately the same\nthickness may exhibit a two order of magnitude difference in their moduli. The\ngood agreement between experiments and simulations illustrated our findings as\nan effective guideline for tailoring the elastic properties of polymer films at\nnanoscale."
    },
    {
        "anchor": "Diffusion and multistage kinetics of macromolecular adsorption: We derive the equations that describe adsorption of diffusing particles onto\na surface followed by additional surface kinetic steps before being transported\nacross the interface. Multistage surface kinetics occurs during membrane\nprotein insertion, cell signaling, and the infection of cells by virus\nparticles. For example, after nonspecific binding, additional kinetic steps,\nsuch as binding of receptors and coreceptors, must occur before virus particle\nfusion can occur. We couple the diffusion of particles in the bulk phase with\nthe surface kinetics and derive an effective, integro-differential boundary\ncondition that contains a memory kernel describing the delay induced by the\nsurface reactions. This boundary condition takes the form of a singular\nperturbation problem in the limit where particle-surface interactions are\nshort-ranged. Moreover, depending on the surface kinetics, the delay kernel\ninduces a nonmonotonic, transient replenishment of the bulk particle\nconcentration near the interface. Our approach generalizes that of Ward and\nTordai, and Diamant and Andelman, to include surface kinetics, giving rise to\nqualitatively new behaviors.",
        "positive": "Structural properties of additive binary hard-sphere mixtures. III.\n  Direct correlation functions: An analysis of the direct correlation functions $c_{ij} (r)$ of binary\nadditive hard-sphere mixtures of diameters $\\sigma_s$ and $\\sigma_b$ (where the\nsubscripts $s$ and $b$ refer to the \"small\" and \"big\" spheres, respectively),\nas obtained with the rational-function approximation method and the WM scheme\nintroduced in previous work [S.\\ Pieprzyk \\emph{et al.}, Phys.\\ Rev.\\ E {\\bf\n101}, 012117 (2020)], is performed. The results indicate that the functions\n$c_{ss}(r<\\sigma_s)$ and $c_{bb}(r<\\sigma_b)$ in both approaches are monotonic\nand can be well represented by a low-order polynomial, while the function\n$c_{sb}(r<\\frac{1}{2}(\\sigma_b+\\sigma_s))$ is not monotonic and exhibits a well\ndefined minimum near $r=\\frac{1}{2}(\\sigma_b-\\sigma_s)$, whose properties are\nstudied in detail. Additionally, we show that the second derivative\n$c_{sb}''(r)$ presents a jump discontinuity at\n$r=\\frac{1}{2}(\\sigma_b-\\sigma_s)$ whose magnitude satisfies the same\nrelationship with the contact values of the radial distribution function as in\nthe Percus-Yevick theory."
    },
    {
        "anchor": "Structural relaxation of porous glasses due to internal stresses and\n  deformation under tensile loading at constant pressure: The time evolution of the pore size distributions and mechanical properties\nof amorphous solids at constant pressure is studied using molecular dynamics\nsimulations. The porous glasses were initially prepared at constant volume\nconditions via a rapid thermal quench from the liquid state to the glassy\nregion and allowing for simultaneous phase separation and material\nsolidification. We found that at constant pressure and low temperature, the\nporous network becomes more compact and the glassy systems relocate to\nprogressively lower levels of the potential energy. Although the elastic\nmodulus and the average glass density both increase with the waiting time,\ntheir dependence is described by the power-law function with the same exponent.\nMoreover, the results of numerical simulations demonstrated that under tensile\nloading at constant pressure, low-density porous samples become significantly\ndeformed and break up into separate domains at high strain, while dense glasses\nform a nearly homogeneous solid material.",
        "positive": "Regimes of wrinkling in pressurized elastic shells: We consider the point-indentation of a pressurized elastic shell. It has\npreviously been shown that such a shell is subject to a wrinkling instability\nas the indentation depth is quasi-statically increased. Here we present\ndetailed analysis of this wrinkling instability using a combination of\nanalytical techniques and finite element simulations. In particular, we study\nhow the number of wrinkles observed at the onset of instability grows with\nincreasing pressurization. We also study how, for fixed pressurization, the\nnumber of wrinkles changes both spatially and with increasing indentation depth\nbeyond onset. This `Far from threshold' analysis exploits the largeness of the\nwrinkle wavenumber that is observed at high pressurization and leads to\nquantitative differences with the standard `Near threshold' stability analysis."
    },
    {
        "anchor": "Cluster and conquer: The morphodynamics of invasion of a compliant\n  substrate by active rods: The colonisation of a soft passive material by motile cells such as bacteria\nis common in biology. The resulting colonies of the invading cells are often\nobserved to exhibit intricate patterns whose morphology and dynamics can depend\non a number of factors, particularly the mechanical properties of the substrate\nand the motility of the individual cells. We use simulations of a minimal 2D\nmodel of self-propelled rods moving through with a passive compliant medium\nconsisting of particles that offer elastic resistance before being plastically\ndisplaced from their equilibrium positions. It is observed that the\nmotility-induced clustering of active (self-propelled) particles is crucial for\nunderstanding the morphodynamics of colonisation. Clustering enables motile\ncolonies to spread faster than they would have as isolated particles. The\ncolonisation rate depends non-monotonically on substrate stiffness with a\ndistinct maximum at a non-zero value of substrate stiffness. This is observed\nto be due to a change in the morphology of clusters. Furrow networks created by\nthe active particles have a fractal-like structure whose dimension varies\nsystematically with substrate stiffness but is less sensitive to particle\nactivity. The power-law growth exponent of the furrowed area is smaller than\nunity, suggesting that, to sustain such extensive furrow networks, colonies\nmust regulate their overall growth rate.",
        "positive": "Directional depletion interactions in shaped particles: Entropic forces in colloidal suspensions and in polymer-colloid systems are\nof long-standing and continuing interest. Experiments show how entropic forces\ncan be used to control the self-assembly of colloidal particles. Significant\nadvances in colloidal synthesis made in the past two decades have enabled the\npreparation of high quality nano-particles with well-controlled sizes, shapes,\nand compositions, indicating that such particles can be utilized as \"artificial\natoms\" to build new materials. To elucidate the effects of the shape of\nparticles upon the magnitude of entropic interaction, we analyse the entropic\ninteractions of two cut-spheres. We show that the solvent induces a strong\ndirectional depletion attraction among flat faces of the cut-spheres. Such an\neffect highlights the possibility of using the shape of particles to control\ndirectionality and strength of interaction."
    },
    {
        "anchor": "Isotropic-Cholesteric Transition of a Weakly Chiral Elastomer Cylinder: When a chiral isotropic elastomer is brought to low temperature cholesteric\nphase, the nematic degree of freedom tends to order and form a helix. Due to\nthe nemato-elastic coupling, this also leads to elastic deformation of the\npolymer network that is locally coaxial with the nematic order. However, the\nhelical structure of nematic order is incompatible with the energetically\npreferred elastic deformation. The system is therefore frustrated and\nappropriate compromise has to be achieved between the nematic ordering and the\nelastic deformation. For a strongly chiral elastomer whose pitch is much\nsmaller than the system size, this problem has been studied by Pelcotivs and\nMeyer, as well as by Warner. In this work, we study the isotropic-cholesteric\ntransition in the weak chirality limit, where the pitch is comparable or much\nlarger than system size. We compare two possible solutions: a helical state as\nwell as a double twist state. We find that the double twist state very\nefficiently minimizes both the elastic free energy and the chiral nematic free\nenergy. On the other hand, the pitch of the helical state is strongly affected\nby the nemato-elastic coupling. As a result this state is not efficient in\nminimizing the chiral nematic free energy.",
        "positive": "Strongly localized anharmonic modes in perfect and imperfect crystals: Localized modes of large amplitudes in nonlinear lattices are considered. The\napplied method allows the reduction of nonlinear problem to a linear inverse\nproblem of phonons scattering on a local potential. The method is efficient in\nthe case of strongly localized modes. Analytical description of such modes in\nmonatomic chain is given. Results of numerical calculations of anharmonic local\nvibrations of light ions in pure and impure alkali halide crystal are\npresented. It is found that, in the case of amplitudes ~0.5A, the vibrations\ndepend very strongly on the crystallographic directions."
    },
    {
        "anchor": "Shapes and textures of ferromagnetic liquid droplets: Theoretical calculations, computer simulations and experiments indicate the\npossible existence of a ferromagnetic liquid state. Should such a state exist,\ndemagnetization effects would force a nontrivial magnetization texture governed\nby the shape of the liquid droplet. Since liquid droplets are deformable, the\ndroplet shape couples to the magnetization texture. This paper solves the joint\nshape/texture problem subject to the assumption of cylindrical droplet\nsymmetry. The shape undergoes a change in topology from spherical to toroidal\nas exchange energy grows or surface tension decreases.",
        "positive": "Crosslinker mobility governs fracture behavior of catch-bonded networks: While most chemical bonds weaken under the action of mechanical force (called\nslip bond behavior), nature has developed bonds that do the opposite: their\nlifetime increases as force is applied. While such catch bonds have been\nstudied quite extensively at the single molecule level and in adhesive\ncontacts, recent work has shown that they are also abundantly present as\ncrosslinkers in the actin cytoskeleton. However, their role and the mechanism\nby which they operate in these networks have remained unclear. Here, we present\ncomputer simulations that show how polymer networks crosslinked with either\nslip or catch bonds respond to mechanical stress. Our results reveal that catch\nbonding may be required to protect dynamic networks against fracture, in\nparticular for mobile linkers that can diffuse freely after unbinding. While\nmobile slip bonds lead to networks that are very weak at high stresses, mobile\ncatch bonds accumulate in high stress regions and thereby stabilize cracks,\nleading to a more ductile fracture behavior. This allows cells to combine\nstructural adaptivity at low stresses with mechanical stability at high\nstresses."
    },
    {
        "anchor": "Coarse-Grained Modeling of Charged Colloidal Suspensions: From\n  Poisson-Boltzmann Theory to Effective Interactions: Electrostatic interactions between macroions largely govern the equilibrium\nthermodynamic and dynamical properties of charge-stabilized colloidal\nsuspensions and polyelectrolyte solutions. Predicting the properties of such\ncomplex, multicomponent systems with accuracy sufficient to guide and interpret\nexperiments requires realistic modeling of the interparticle interactions and\ncollective behavior of many-particle systems. While the fundamental\ninteractions may be simple, the sheer number of particles and the broad ranges\nof length and time scales confront the modeler with significant computational\nchallenges. A general strategy for mitigating such challenges is to \"coarse\ngrain\" or \"integrate out\" the degrees of freedom of some components, reducing\nthe original multicomponent model to a simpler model of fewer components. The\ntrade-off for so reducing complexity is that the simpler model is governed by\nmodified (effective) interparticle interactions. This chapter is a \"how-to\"\nmanual for implementing coarse-graining methods to derive effective\nelectrostatic interactions in systems of charged macroions. After reviewing the\ncell model implementation of the Poisson-Boltzmann theory of charged colloids\nand polyelectrolytes, we describe an alternative implementation, based on\nperturbation theory. From a linear response approximation, we derive effective\nelectrostatic interactions for charge-stabilized suspensions of spherical\ncolloids.",
        "positive": "Spectral statistics of the quenched normal modes of a network-forming\n  molecular liquid: We evaluate the density of states of the quenched normal modes of ST2 water,\nand their statistical fluctuations, for a range of densities spanning three\nregimes of behavior of a hydrogen bonded liquid: a lower-density regime of\nrandom tetrahedral network formation; in the vicinity of a liquid-liquid\ncritical point; and in a higher-density regime of fragile glass-forming\nbehavior. For all cases we find that the fluctuations around the mean spectral\ndensities obey the predictions of the Gaussian orthogonal ensemble of random\nmatrix theory. We also measure the participation ratio of the normal modes\nacross the entire frequency range, and find behavior consistent with the\nmajority of modes being of an extended nature, rather than localized."
    },
    {
        "anchor": "Local dielectric response in 1-propanol: $\u03b1$-relaxation versus\n  relaxation of mesoscale structures: The dielectric Debye relaxation in monohydroxy alcohols has been subject of\nlong-standing scientific interest and is presently believed to arise from the\nrelaxation of transiently H-bonded supramolecular structures. Therefore, its\nmanifestation might be expected to differ from a local dielectric probe as\ncompared to the standard macroscopic dielectric experiment. In this work we\npresent such local dielectric measurements obtained by triplet state solvation\ndynamics (TSD) and compare the results with macroscopic dielectric and light\nscattering data. In particular, with data from an improved TSD setup, a\ndetailed quantitative comparison reveals that the Debye process does not\nsignificantly contribute to the local Stokes shift response function, while\n$\\alpha$- and $\\beta$-relaxations are clearly resolved. Furthermore, this\ncomparison reveals that the structural relaxation has almost identical time\nconstants and shape parameters in all three measurement techniques. Altogether\nour findings support the notion that the transiently bound chain structures\nlead to a strong cross-correlation contribution in macroscopic dielectric\nexperiments, to which both light scattering and TSD are insensitive, the latter\ndue to its local character and the former due to the molecular optical\nanisotropy being largely independent of the OH bonded suprastructures.",
        "positive": "A threshold model of plastic waste fragmentation: New insights into the\n  distribution of microplastics in the ocean and its evolution over time: Plastic pollution in the aquatic environment has been assessed for many years\nby ocean waste collection expeditions around the globe or by river sampling.\nWhile the total amount of plastic produced worldwide is well documented, the\namount of plastic found in the ocean, the distribution of particles on its\nsurface and its evolution over time are still the subject of much debate. In\nthis article, we propose a general fragmentation model, postulating the\nexistence of a critical size below which particle fragmentation becomes\nextremely unlikely. In the frame of this model, an abundance peak appears for\nsizes around 1mm, in agreement with real environmental data. Using, in\naddition, a realistic exponential waste feed to the ocean, we discuss the\nrelative impact of fragmentation and feed rates, and the temporal evolution of\nmicroplastics (MP) distribution. New conclusions on the temporal trend of MP\npollution are drawn."
    },
    {
        "anchor": "Chiral Self-Assembly of Cellulose Nanocrystals is Driven by Crystallite\n  Bundles: The transfer of chirality across length-scales is an intriguing and universal\nnatural phenomenon. However, connecting the properties of individual building\nblocks to the emergent features of their resulting large-scale structure\nremains a challenge. In this work, we investigate the origins of mesophase\nchirality in cellulose nanocrystal suspensions, whose self-assembly into chiral\nphotonic films has attracted significant interest. By correlating the ensemble\nbehaviour in suspensions and films with a quantitative morphological analysis\nof the individual nanoparticles, we reveal an inverse relationship between the\ncholesteric pitch and the abundance of laterally-bound composite particles.\nThese bundles thus act as colloidal chiral dopants, analogous to those used in\nmolecular liquid crystals, providing the missing link in the hierarchical\ntransfer of chirality from the molecular to the colloidal scale.",
        "positive": "Ultrafast Spontaneous Motion of Nanodroplets: Making liquid droplets move spontaneously on solid surfaces is a key\nchallenge in lab-on-chip and heat exchanger technologies. The best-known\nmechanism, a wettability gradient, does not generally move droplets rapidly\nenough and cannot drive droplets smaller than a critical size. Here we report\nhow a curvature gradient is particularly effective at accelerating small\ndroplets, and works for both hydrophilic and hydrophobic surfaces. Experiments\nfor water droplets on tapered surfaces with curvature radii in the\nsub-millimeter range show a maximum speed of 0.28 m/s, two orders of magnitude\nhigher than obtained by wettability gradient. We show that the force exerted on\na droplet scales as the surface curvature gradient. Using molecular dynamics\nsimulations, we observe nanoscale droplets moving spontaneously at over 100 m/s\non tapered surfaces."
    },
    {
        "anchor": "Condensation of Silica Nanoparticles on a Phospholipid Membrane: The structure of the transient layer at the interface between air and the\naqueous solution of silica nanoparticles with the size distribution of\nparticles that has been determined from small-angle scattering has been studied\nby the X-ray reflectometry method. The reconstructed depth profile of the\npolarizability of the substance indicates the presence of a structure\nconsisting of several layers of nanoparticles with the thickness that is more\nthan twice as large as the thickness of the previously described structure. The\nadsorption of 1,2-distearoyl-sn-glycero-3-phosphocholine molecules at the\nhydrosol/air interface is accompanied by the condensation of anion silica\nnanoparticles at the interface. This phenomenon can be qualitatively explained\nby the formation of the positive surface potential due to the penetration and\naccumulation of Na+ cations in the phospholipid membrane.",
        "positive": "Depth-dependent resistance of granular media to vertical penetration: We measure the quasi-static friction force acting on intruders moving\ndownwards into a granular medium. By utilizing different intruder geometries,\nwe demonstrate that the force acts locally normal to the intruder surface. By\naltering the hydrostatic loading of grain contacts by a sub-fluidizing airflow\nthrough the bed, we demonstrate that the relevant frictional contacts are\nloaded by gravity rather than by the motion of the intruder itself. Lastly, by\nmeasuring the final penetration depth versus airspeed and using an earlier\nresult for inertial drag, we demonstrate that the same quasi-static friction\nforce acts during impact. Altogether this force is set by a friction\ncoefficient, hydrostatic pressure, projectile size and shape, and a\ndimensionless proportionality constant. The latter is the same in nearly all\nexperiments, and is surprisingly greater than one."
    },
    {
        "anchor": "Elastic response of colloidal smectics: insights from microscopic theory: Elongated colloidal rods at sufficient packing conditions are known to form\nstable lamellar or smectic phases. Using a simplified volume-exclusion model,\nwe propose a generic equation-of-state for hard-rod smectics that is robust\nagainst simulation results and is independent of the rod aspect ratio. We then\nextend our theory by exploring the elastic properties of a hard-rod smectic,\nincluding the layer compressibility ($B$) and bending modulus ($K_{1}$). By\nintroducing weak backbone flexibility we are able to compare our predictions\nwith experimental results on smectics of filamentous virus rods and find\nquantitative agreement between the smectic layer spacing, the out-of-plane\nfluctuation strength, as well as the smectic penetration length $\\lambda =\n\\sqrt{K_{1}/B}$. We demonstrate that the layer bending modulus is dominated by\ndirector splay and depends sensitively on lamellar out-of-plane fluctuations\nthat we account for on the single-rod level. We find that the ratio between the\nsmectic penetration length and the lamellar spacing is about two orders of\nmagnitude smaller than typical values reported for thermotropic smectics. We\nattribute this to the fact that colloidal smectics are considerably softer in\nterms of layer compression than their thermotropic counterparts while the cost\nof layer bending is of comparable magnitude.",
        "positive": "Influence of thermal fluctuations on active diffusion at large\n  P\u00e9clet numbers: Wavelet Monte Carlo dynamics simulations are used to study the dynamics of\npassive particles in the presence of microswimmers, taking account of the\noften-omitted thermal motion alongside the hydrodynamic flows generated by the\nswimmers. Although the P\\'{e}clet numbers considered are large, we find the\nthermal motion to have a significant effect on the dynamics of our passive\nparticles, and can be included as a decorrelation factor in the velocity\nautocorrelation with a decay time proportional to the P\\'{e}clet number.\nSimilar decorrelation factors come from swimmer rotations, e.g.~run and tumble\nmotion, and apply to both entrainment and far field loop contributions. These\ndecorrelation factors lead to active diffusivity having a weak apparent power\nlaw close to $Pe^{0.2}$ for small tracer-like particles at P\\'{e}clet numbers\nappropriate for E. coli swimmers at room temperature. Meanwhile, the reduced\nhydrodynamic response of large particles to nearby forces has a corresponding\nreduction in active diffusivity in that regime. Together, they lead to a\nnon-monotonic dependence of active diffusivity on particle size that can shed\nlight on similar behaviour observed in experiments by Patteson et al."
    },
    {
        "anchor": "Single particle fluctuations dominate the long-time dynamic\n  susceptibility in glass-forming liquids: Liquids near the glass transition exhibit dynamical heterogeneity, i.e.\ncorrelated regions in the liquid relax at either a much faster rate or a much\nslower rate than the average. This collective phenomenon has been characterized\nby measurements of a dynamic susceptibility $\\chi_4(t)$, which are sometimes\ninterpreted in terms of the size of those relaxing regions and the intensity of\nthe fluctuations. We show that the results of those measurements can be\naffected not only by the collective fluctuations in the relaxation rate, but\nalso by density fluctuations in the initial state and by single-particle\nfluctuations. We also show that at very long times the average overlap $C(t)$\nprobing the similarity between an initial and a final state separated by a time\ninterval $t$ decays as a power law $C(t) \\sim t^{-d/2}$. This is much slower\nthan the stretched exponential behavior $C(t) \\sim {\\rm e}^{-(t/\\tau)^{\\beta}}$\npreviously observed at times within one or two orders of magnitude of the\n$\\alpha$-relaxation time $\\tau_{\\alpha}$. We find that for times longer than\n$10-100 \\tau_{\\alpha}$, the dynamic susceptibility $\\chi_4(t)$ is dominated by\nsingle particle fluctuations, and that $\\chi_4(t) \\approx C(t) \\sim t^{-d/2}$.\nFinally, we introduce a method to extract the collective relaxation\ncontribution to the dynamic susceptibility $\\chi_4(t)$ by subtracting the\neffects of single-particle fluctuations and initial state density fluctuations.\nWe apply this method to numerical simulations of two glass forming models: a\nbinary hard sphere system and a Kob-Andersen Lennard-Jones system. This allows\nus to extend the analysis of numerical data to timescales much longer than\npreviously possible, and opens the door for further future progress in the\nstudy of dynamic heterogeneities, including the determination of the exchange\ntime.",
        "positive": "Confined colloidal crystals in and out of equilibrium: Recent studies on confined crystals of charged colloidal particles are\nreviewed, both in equilibrium and out of equilibrium. We focus in particular on\ndirect comparisons of experiments (light scattering and microscopy) with\nlattice sum calculations and computer simulations. In equilibrium we address\nbuckling and crystalline multilayering of charged systems in hard and soft slit\nconfinement. We discuss also recent crystalline structures obtained for charged\nmixtures. Moreover, we put forward possibilities to apply external\nperturbations, in order to drive the system out of equilibrium. These include\nelectrolyte gradients as well as the application of shear and electric fields."
    },
    {
        "anchor": "DNA versus RNA -- which shows higher electronic conduction?: In this study, we compare the charge transport properties of multiple (double\nstranded) dsRNA sequences with corresponding dsDNA sequences. Recent studies\nhave presented a contradictory picture of relative charge transport\nefficiencies in A-form DNA:RNA hybrids and dsDNA. Using a multiscale modelling\nframework, we compute conductance of dsDNA and dsRNA using Landauer formalism\nin coherent limit and Marcus-Hush theory in the incoherent limit. We find that\ndsDNA conducts better than dsRNA in both the charge transport regimes. Our\nanalysis shows that the structural differences in the twist angle and slide of\ndsDNA and dsRNA are the main reasons behind the higher conductance of dsDNA in\nthe incoherent hopping regime. In the coherent limit however, for the same base\npair length, the conductance of dsRNA is higher than that of dsDNA for the\nmorphologies where dsRNA has smaller end-to-end length relative to that of\ndsDNA.",
        "positive": "Post-buckling Dynamics of Spherical Shells: We explore the intrinsic dynamics of spherical shells immersed in a fluid in\nthe vicinity of their buckled state, through experiments and 3D axisymmetric\nsimulations. The results are supported by a theoretical model that accurately\ndescribes the buckled shell as a two-variable-only oscillator. We quantify the\neffective \"softening\" of shells above the buckling threshold, as observed in\nrecent experiments on interactions between encapsulated microbubbles and\nacoustic waves. The main dissipation mechanism in the neighboring fluid is also\nevidenced."
    },
    {
        "anchor": "Equilibrium route to colloidal gellation: mixtures of hard sphere-like\n  colloids: The binodals and the non-ergodicity lines of a binary mixture of hard\nsphere-like particles with large size ratio are computed for studying the\ninterplay between dynamic arrest and phase separation in depletion-driven\ncolloidal mixtures. Contrarily to the case of hard core plus short range\neffective attraction, physical gellation without competition with the\nfluid-phase separation can occur in such mixtures. This behavior due to the\noscillations in the depletion potential should concern all simple mixtures with\nnon-ideal depletant, justifying further studies of their dynamic properties.",
        "positive": "Spontaneous aggregation and global polar ordering in squirmer\n  suspensions: We have developed numerical simulations of three dimensional suspensions of\nactive particles to characterize the capabilities of the hydrodynamic stresses\ninduced by active swimmers to promote global order and emergent structures in\nactive suspensions. We have considered squirmer suspensions embedded in a fluid\nmodeled under a Lattice Boltzmann scheme. We have found that active stresses\nplay a central role to decorrelate the collective motion of squirmers and that\ncontractile squirmers develop significant aggregates."
    },
    {
        "anchor": "Light scattering by a metallic nanoparticle coated with a nematic liquid\n  crystal: We study the optical properties of gold nanoparticles coated with a nematic\nliquid crystal whose director field is distributed around the nanoparticle\naccording to the anchoring conditions at the surface of the nanoparticle. The\ndistribution of the nematic liquid crystal is obtained by minimization of the\ncorresponding Frank free-energy functional whilst the optical response is\ncalculated by the discrete-dipole approximation. We find, in particular, that\nthe anisotropy of the nematic liquid-crystal coating does not affect much the\n(isotropic) optical response of the nanoparticle. However, for strong anchoring\nof the nematic liquid-crystal molecules on the surface of nanoparticle, the\ninhomogeneity of the coating which is manifested by a ring-type singularity\n(disclination or Saturn ring), produces an enhancement of the extinction cross\nspectrum over the entire visible spectrum.",
        "positive": "Bimodal molecular mass distribution in surfactant-free emulsion\n  polymerization as a consequence of coagulative nucleation: It is demonstrated that the often observed broadness of the molecular weight\ndistribution obtained from latex particles synthesized by means of\nsurfactant-free emulsion polymerization results from the multistage kinetics.\nThe initial stage of the polymerization, by which the primary particles are\nformed, is of the 01-kind which means that it can be assumed that the particles\nare so small that at any moment of time there is no more than one radical chain\nper particle. After the aggregation of primary particles into secondary\nparticles, the so called coagulative nucleation step, the polymerization\nkinetics in the subsequently coalesced secondary particles is of the\npseudo-bulk kind which means that there are so many radicals in the particles\nthat the polymerization process proceeds as in bulk. The important consequence\nis that the molecular weight of the 01-process is about one order of magnitude\nlarger than that of the pseudo-bulk process. Hence, each of these\npolymerization modes and the aggregation stage in-between leave their traces in\nthe molecular weight distribution as is shown by experiments aimed at\nprolonging the initial formation kinetics. Bimodal molecular weight\ndistributions are found both for ionic and non-ionic initiators."
    },
    {
        "anchor": "Electrophoresis of colloidal dispersions in the low-salt regime: We study the electrophoretic mobility of spherical charged colloids in a\nlow-salt suspension as a function of the colloidal concentration. Using an\neffective particle charge and a reduced screening parameter, we map the data\nfor systems with different particle charges and sizes, including numerical\nsimulation data with full electrostatics and hydrodynamics and experimental\ndata for latex dispersions, on a single master curve. We observe two different\nvolume fraction-dependent regimes for the electrophoretic mobility that can be\nexplained in terms of the static properties of the ionic double layer.",
        "positive": "Fluctuations in Symmetric Diblock Copolymers: Testing A Recent Theory: Composition fluctuations in disordered melts of symmetric diblock copolymers\nare studied by Monte Carlo simulation over a range of chain lengths and\ninteraction strengths. Results are used to test three theories: (1) the random\nphase approximation (RPA), (2) the Fredrickson-Helfand (FH) theory, which was\ndesigned to describe large fluctuations near an order-disorder transition\n(ODT), and (3) a more recent renormalized one-loop (ROL) theory, which reduces\nto FH theory near the ODT, but which is found to be accurate over a much wider\nrange of parameters."
    },
    {
        "anchor": "Pressure evolution and deformation of confined granular media during\n  pneumatic fracturing: By means of digital image correlation, we experimentally characterize the\ndeformation of a dry granular medium confined inside a Hele-Shaw cell due to\nair injection at a constant overpressure high enough to deform it (from 50 to\n250 kPa). Air injection at these overpressures leads to the formation of so\ncalled pneumatic fractures, i.e. channels empty of beads, and we discuss the\ntypical deformations of the medium surrounding these structures. In addition we\nsimulate the diffusion of the fluid overpressure into the medium, comparing it\nwith the Laplacian solution over time, and relating pressure gradients with\ncorresponding granular displacements. In the compacting medium we show that the\ndiffusing pressure field becomes similar to the Laplace solution on the order\nof a characteristic time given by properties of the pore fluid, granular medium\nand the system size. However, before the diffusing pressure approaches the\nLaplace solution on system scale, we find that it resembles the Laplacian field\nnear the channels, with the highest pressure gradients on the most advanced\nchannel tips and a screened pressure gradient behind them. We show that the\ngranular displacements more or less always move in the direction against the\nlocal pressure gradients, and when comparing granular velocities with pressure\ngradients in the zone ahead of channels, we observe a Bingham type of rheology\nfor the granular paste (the mix of air and beads), with an effective viscosity\n$\\mu\\_B$ and displacement thresholds $\\nabla P\\_c$ evolving during mobilization\nand compaction of the medium. Such a rheology, with disorder in the\ndisplacement thresholds, could be responsible for placing the pattern growth at\nmoderate injection pressures in a universality class like the Dielectric\nBreakdown Model with $\\eta=2$, where fractal dimensions are found between 1.5\nand 1.6 for the patterns.",
        "positive": "Filament actuation by an active colloid at low Reynolds number: Active colloids and externally actuated semi-flexible filaments provide basic\nbuilding blocks for designing autonomously motile micro-machines. Here, we show\nthat a passive semi-flexible filament can be actuated and transported by\nattaching an active colloid to its terminus. We study the dynamics of this\nassembly when it is free, tethered, or clamped using overdamped equations of\nmotion that explicitly account for active fluid flow and the forces it\nmediates. Linear states are destabilized by buckling instabilities to produce\nstable states of non-zero curvature and writhe. We demarcate boundaries of\nthese states in the two-dimensional parameter space representing dimensionless\nmeasures of polar and apolar activity. Our proposed assembly can be used as a\nnovel component in the design of micro-machines at low Reynolds number and to\nstudy elastic instabilities driven by \"follower\" forces."
    },
    {
        "anchor": "Bridge-mediated Donor-Acceptor Effective Coupling: Exact theoretical\n  description: An exact expression of the bridge-mediated donor-acceptor effective coupling,\nis derived. For systems represented by a tight-binding Hamiltonian with\nnearest-neighbor interactions, we show that the effective coupling, is equal to\nthe product over all square of nearest-neighbor couplings divided by an\nappropriate product of level spacing of eigen energies of the Hamiltonian.\nResults of this calculation are compared to those obtained by perturbative\napproaches and some drawbacks of the latter are pointed out.",
        "positive": "Onset of thermal convection in a horizontal layer of granular gas: The Navier-Stokes granular hydrodynamics is employed for determining the\nthreshold of thermal convection in an infinite horizontal layer of granular\ngas. The dependence of the convection threshold, in terms of the inelasticity\nof particle collisions, on the Froude and Knudsen numbers is found. A simple\nnecessary condition for convection is formulated in terms of the\nSchwarzschild's criterion, well-known in thermal convection of (compressible)\nclassical fluids. The morphology of convection cells at the onset is\ndetermined. At large Froude numbers, the Froude number drops out of the\nproblem. As the Froude number goes to zero, the convection instability turns\ninto a recently discovered phase separation instability."
    },
    {
        "anchor": "Deformable self-propelled particles: A theory of self-propelled particles is developed in two dimensions assuming\nthat the particles can be deformed from a circular shape when the propagating\nvelocity is increased. A coupled set of equations in terms of the velocity and\na tensor variable to represent the deformation is introduced to show that there\nis a bifurcation from a straight motion to a circular motion of a single\nparticle. Dynamics of assembly of the particles is studied numerically where\nthere is a global interaction such that the particles tend to cause an\norientational order.",
        "positive": "Kinetic dielectric decrement revisited: phenomenology of finite ion\n  concentrations: With the help of a recently developed non-equilibrium approach, we\ninvestigate the ionic strength dependence of the Hubbard--Onsager dielectric\ndecrement. We compute the depolarization of water molecules caused by the\nmotion of ions in sodium chloride solutions from the dilute regime (0.035 M) up\nclose to the saturation concentration (4.24 M), and find that the kinetic\ndecrement displays a strong nonmonotonic behavior, in contrast to the\nprediction of available models. We introduce a phenomenological modification of\nthe Hubbard--Onsager continuum theory, that takes into account the screening\ndue to the ionic cloud at mean field level, and, is able to describe the\nkinetic decrement at high concentrations including the presence of a pronounced\nminimum."
    },
    {
        "anchor": "Strongly correlating liquids and their isomorphs: This paper summarizes the properties of strongly correlating liquids, i.e.,\nliquids with strong correlations between virial and potential energy\nequilibrium fluctuations at constant volume. We proceed to focus on the\nexperimental predictions for strongly correlating glass-forming liquids. These\npredictions include i) density scaling, ii) isochronal superposition, iii) that\nthere is a single function from which all frequency-dependent viscoelastic\nresponse functions may be calculated, iv) that strongly correlating liquids are\napproximately single-parameter liquids with close to unity Prigogine-Defay\nratio, and v) that the fictive temperature initially decreases for an isobaric\ntemperature up jump. The \"isomorph filter\", which allows one to test for\nuniversality of theories for the non-Arrhenius temperature dependence of the\nrelaxation time, is also briefly discussed.",
        "positive": "Multivalent ion effects on electrostatic stability of virus-like\n  nano-shells: Electrostatic properties and stability of charged virus-like nano-shells are\nexamined in ionic solutions with monovalent and multivalent ions. A theoretical\nmodel based on a thin charged spherical shell and multivalent ions within the\n\"dressed multivalent ion\" approximation, yielding their distribution across the\nshell and the corresponding electrostatic (osmotic) pressure acting on the\nshell, is compared with extensive implicit Monte-Carlo simulations. It is found\nto be accurate for positive or low negative surface charge densities of the\nshell and for sufficiently high (low) monovalent (multivalent) salt\nconcentrations. Phase diagrams involving electrostatic pressure exhibit\npositive and negative values, corresponding to an outward and an inward facing\nforce on the shell, respectively. This provides an explanation for the high\nsensitivity of viral shell stability and self-assembly of viral capsid shells\non the ionic environment."
    },
    {
        "anchor": "How do dynamic heterogeneities evolve in time?: We present simulations of a hard disc system and analyze the time evolution\nof the dynamic heterogeneities. We characterize the time evolution of slow\nregions and slow particles individually. The motion of slow clusters turns out\nto be very restricted, i.e. a cluster is generated and annihilated in a spatial\nregion four times the size of its maximum extent. The residual motion of the\ncluster can be traced back to subdiffusive motion of the constituent particles\nand the process of absorption and loss of adjacent particles. The subdiffusive\ndynamics is independent of how long the particles remain slow. Clusters of fast\nparticles show an even smaller reach, which seems to be due to their short life\ntime.",
        "positive": "Transport of active ellipsoidal particles in ratchet potentials: Rectified transport of active ellipsoidal particles is numerically\ninvestigated in a two-dimensional asymmetric potential. The out-of-equilibrium\ncondition for the active particle is an intrinsic property, which can break\nthermodynamical equilibrium and induce the directed transport. It is found that\nthe perfect sphere particle can facilitate the rectification, while the\nneedlelike particle destroys the directed transport. There exist optimized\nvalues of the parameters (the self-propelled velocity, the torque acting on the\nbody) at which the average velocity takes its maximal value. For the\nellipsoidal particle with not large asymmetric parameter, the average velocity\ndecreases with increasing the rotational diffusion rate, while for the\nneedlelike particle (very large asymmetric parameter), the average velocity is\na peaked function of the rotational diffusion rate. By introducing a finite\nload, particles with different shapes (or different self-propelled velocities)\nwill move to the opposite directions, which is able to separate particles of\ndifferent shapes (or different self-propelled velocities)."
    },
    {
        "anchor": "Experimental measurements of stress redistribution in flowing emulsions: We study how local rearrangements alter droplet stresses within flowing dense\nquasi-two-dimensional emulsions at area fractions $\\phi \\geq 0.88$. Using\nmicroscopy, we measure droplet positions while simultaneously using their\ndeformed shape to measure droplet stresses. We find that rearrangements alter\nnearby stresses in a quadrupolar pattern: stresses on neighboring droplets tend\nto either decrease or increase depending on location. The stress redistribution\nis more anisotropic with increasing $\\phi$. The spatial character of the stress\nredistribution influences where subsequent rearrangements occur. Our results\nprovide direct quantitative support for rheological theories of dense amorphous\nmaterials that connect local rearrangements to changes in nearby stress.",
        "positive": "Molecular Correlation Functions for Uniaxial Ellipsoids in the Isotropic\n  State: We perform event-driven molecular dynamics simulations of a system composed\nby uniaxial hard ellipsoids for different values of the aspect-ratio and\npacking fraction . We compare the molecular orientational-dependent structure\nfactors previously calculated within the Percus-Yevick approximation with the\nnumerical results. The agreement between theoretical and numerical results is\nrather satisfactory. We also show that, for specific orientational quantities,\nthe molecular structure factors are sensitive to the particle shape and can be\nused to distinguish prolate from oblate ellipsoids. A first-order theoretical\nexpansion around the spherical shape and a geometrical analysis of the\nconfigurations confirms and explains such an observation."
    },
    {
        "anchor": "Harnessing entropy to enhance toughness in reversibly crosslinked\n  polymer networks: Reversible crosslinking is a design paradigm for polymeric materials, wherein\nthey are microscopically reinforced with chemical species that form transient\ncrosslinks between the polymer chains. Besides the potential for self-healing,\nrecent experimental work suggests that freely diffusing reversible crosslinks\nin polymer networks, such as gels, can enhance the toughness of the material\nwithout substantial change in elasticity. This presents the opportunity for\nmaking highly elastic materials that can be strained to a large extent before\nrupturing. Here, we employ Gaussian chain theory, molecular simulation, and\npolymer self-consistent field theory for networks to construct an equilibrium\npicture for how reversible crosslinks can toughen a polymer network without\naffecting its linear elasticity. Maximisation of polymer entropy drives the\nreversible crosslinks to bind preferentially near the permanent crosslinks in\nthe network, leading to local molecular reinforcement without significant\nalteration of the network topology. In equilibrium conditions, permanent\ncrosslinks share effectively the load with neighbouring reversible crosslinks,\nforming multi-functional crosslink points. The network is thereby globally\ntoughened, while the linear elasticity is left largely unaltered. Practical\nguidelines are proposed to optimise this design in experiment, along with a\ndiscussion of key kinetic and timescale considerations.",
        "positive": "Scalar evolution equations for shear waves in incompressible solids: A\n  simple derivation of the Z, ZK, KZK, and KP equations: We study the propagation of two-dimensional finite-amplitude shear waves in a\nnonlinear pre-strained incompressible solid, and derive several asymptotic\namplitude equations in a simple, consistent, and rigorous manner. The scalar\nZabolotskaya (Z) equation is shown to be the asymptotic limit of the equations\nof motion for all elastic generalized neo-Hookean solids (with strain energy\ndepending only on the first principal invariant of Cauchy-Green strain).\nHowever, we show that the Z equation cannot be a scalar equation for the\npropagation of two-dimensional shear waves in general elastic materials (with\nstrain energy depending on the first and second principal invariants of\nstrain). Then we introduce dispersive and dissipative terms to deduce the\nscalar Kadomtsev-Petviashvili (KP), Zabolotskaya-Khokhlov (ZK) and\nKhokhlov-Zabolotskaya-Kuznetsov (KZK) equations of incompressible solid\nmechanics."
    },
    {
        "anchor": "Modeling silo clogging with nonlocal granular rheology: Granular flow in a silo demonstrates multiple nonlocal rheological phenomena\ndue to the finite size of grains. We solve the Nonlocal Granular Fluidity (NGF)\ncontinuum model in quasi-2D silo geometries and evaluate its ability to predict\nthese nonlocal effects, including flow spreading and, importantly, clogging\n(arrest) when the opening is small enough. The model is augmented to include a\nfree-separation criterion and is implemented numerically with an extension of\nthe trans-phase granular flow solver described in arXiv:1411.5447, to produce\nfull-field solutions. The implementation is validated against analytical\nresults of the model in the inclined chute geometry, such as the solution for\nthe $H_{\\mathrm{stop}}$ curve for size-dependent flow arrest, and the velocity\nprofile as a function of layer height. We then implement the model in the silo\ngeometry and vary the apparent grain size. The model predicts a jamming\ncriterion when the opening competes with the scale of the mean grain size,\nwhich agrees with previous experimental studies, marking the first time to our\nknowledge that silo jamming has been achieved with a continuum model. For\nlarger openings, the flow within the silo obtains a diffusive characteristic\nwhose spread depends on the model's nonlocal amplitude and the mean grain size.\nThe numerical tests are controlled for grid effects and a comparison study of\ncoarse vs refined numerical simulations shows agreement in the pressure field,\nthe shape of the arch in a jammed silo configuration, and the velocity field in\na flowing configuration.",
        "positive": "Capillary condensation for fluids in spherical cavities: The capillary condensation for fluids into spherical nano-cavities is\nanalyzed within the frame of two theoretical approaches. One description is\nbased on a widely used simplified version of the droplet model formulated for\nstudying atomic nuclei. The other, is a more elaborated calculation performed\nby applying a density functional theory. The agreement between both models is\nexamined and it is shown that a small correction to the simple fluid model\nimproves the predictions. A connection to results previously obtained for\nplanar slits and cylindrical pores is done."
    },
    {
        "anchor": "Migration of Active Rings in Porous Media: Inspired by how the shape deformations in active organisms help them to\nmigrate through disordered porous environments, we simulate active ring\npolymers in two-dimensional random porous media. Flexible and inextensible\nactive ring polymers navigate smoothly through the disordered media. In\ncontrast, semiflexible rings undergo transient trapping inside the pore space;\nthe degree of trapping is inversely correlated with the increase in activity.\nWe discover that flexible rings swell while inextensible and semiflexible rings\nmonotonically shrink upon increasing the activity. Together, our findings\nidentify the optimal migration of active ring polymers through porous media.",
        "positive": "Super-Hydrophobic Multi-Walled Carbon Nanotube Coatings for Stainless\n  Steel: We have taken advantage of the native surface roughness and the iron content\nof AISI 316 stainless steel to direct grow multi-walled carbon nanotube (MWCNT)\nrandom networks by chemical vapor deposition (CVD) at low-temperature ($<\n1000^{\\circ}$C), without the addition of any external catalysts or\ntime-consuming pre-treatments. In this way, super-hydrophobic MWCNT films on\nstainless steel sheets were obtained, exhibiting high contact angle values\n($154^{\\circ}$) and high adhesion force (high contact angle hysteresis).\nFurthermore, the investigation of MWCNT films at scanning electron microscopy\n(SEM) reveals a two-fold hierarchical morphology of the MWCNT random networks\nmade of hydrophilic carbonaceous nanostructures on the tip of hydrophobic\nMWCNTs. Owing to the Salvinia effect, the hydrophobic and hydrophilic composite\nsurface of the MWCNT films supplies a stationary super-hydrophobic coating for\nconductive stainless steel. This biomimetical inspired surface not only may\nprevent corrosion and fouling but also could provide low-friction and\ndrag-reduction."
    },
    {
        "anchor": "Nonlinear Elasticity, Fluctuations and Heterogeneity of Nematic\n  Elastomers: Liquid crystal elastomers realize a fascinating new form of soft matter that\nis a composite of a conventional crosslinked polymer gel (rubber) and a liquid\ncrystal. These {\\em solid} liquid crystal amalgams, quite similarly to their\n(conventional, fluid) liquid crystal counterparts, can spontaneously partially\nbreak translational and/or orientational symmetries, accompanied by novel soft\nGoldstone modes. As a consequence, these materials can exhibit unconventional\nelasticity characterized by symmetry-enforced vanishing of some elastic moduli.\nThus, a proper description of such solids requires an essential modification of\nthe classical elasticity theory. In this work, we develop a {\\em rotationally\ninvariant}, {\\em nonlinear} theory of elasticity for the nematic phase of ideal\nliquid crystal elastomers. We show that it is characterized by soft modes,\ncorresponding to a combination of long wavelength shear deformations of the\nsolid network and rotations of the nematic director field. We study thermal\nfluctuations of these soft modes in the presence of network heterogeneities and\nshow that they lead to a large variety of anomalous elastic properties, such as\nsingular length-scale dependent shear elastic moduli, a divergent elastic\nconstant for splay distortion of the nematic director, long-scale\nincompressibility, universal Poisson ratios and a nonlinear stress-strain\nrelation fo arbitrary small strains. These long-scale elastic properties are\n{\\em universal}, controlled by a nontrivial zero-temperature fixed point and\nconstitute a qualitative breakdown of the classical elasticity theory in\nnematic elastomers. Thus, nematic elastomers realize a stable ``critical\nphase'', characterized by universal power-law correlations, akin to a critical\npoint of a continuous phase transition, but extending over an entire phase.",
        "positive": "Critical-like behavior of ionic-related, low-frequency dielectric\n  properties in compressed liquid crystalline 8OCB and its nanocolloid: The report presents pressure-related broadband dielectric spectroscopy (BDS)\nstudies in liquid crystalline octyloxycyanbiphenyl and its nanocolloid with\nBaTiO3 nanoparticles, focused on the low-frequency ionic domain and the impact\nof pretransitional fluctuations. Hence basic exogenic (pressure) and endogenic\n(nanoparticles) impacts on dielectric properties are addressed. The innovative\nderivative-based analysis revealed functional 'critical-like' descriptions of\nionic contributions to dielectric permittivity and electric conductivity. The\nsupplementary dielectric constant scan, yielding insight into dipole-diple\narrangements, is also presented. Studies cover the puzzling case of complex\nliquid (SmA) - Solid crystal phase transition, revealing relatively strong\ncritical-like premelting effects, which have hardly been observed for the\ndiscontinuous 'melting transition' so far."
    },
    {
        "anchor": "Extracting mechanical work from a scalar field potential via dissipative\n  structures: Further thermodynamic investigations into the behaviour of a polar dielectric\nworking fluid under non-equilibrium and negative pressure conditions are\nreported. The establishment of a long-range van der Waals interaction between\nclathrate hydrates and their former guest molecules is revisited. The\ndissipative nature of these inclusion compounds appears responsible for\nsecond-order phase changes that maintain a constant Hamiltonian function\ndespite distinct changes in phase symmetry. A scalar field potential, as\nderived from the Lagrangian function, is deemed responsible for the flow of\nenergy within the system. The inclusion compounds are embedded in a\ngeometrically frustrated fluid lattice which together form a spin ice material.\nThe effective magnetic monopoles of the spin ice appear to exchange energy with\nthe long-range van der Waals interaction on a hyperbolic manifold to produce\nmechanical work. For expansion work, the exchange of energy continues up to a\ntransition point where the auxiliary magnetic field is deemed reach zero\npotential. However, expansion work continues well beyond this transition point,\ndriven by a gradient energy that now exceeds the expression of curvature on the\nhyperbolic manifold. Emergent geometry associated with vacuum energy is\nproposed as the most likely source for the missing energy contribution.",
        "positive": "Low-energy vibrational density of states of plasticized poly(methyl\n  methacrylate): The low-energy vibrational density of states (VDOS)of hydrogenated or\ndeuterated poly(methyl methacrylate)(PMMA)plasticized by dibutyl phtalate (DBP)\nis determined by inelastic neutron scattering.From experiment, it is equal to\nthe sum of the ones of the PMMA and DBP components.However, a partition of the\ntotal low-energy VDOS among PMMA and DBP was observed.Contrary to Raman\nscattering, neutron scattering does not show enhancement of the boson peak due\nto plasticization."
    },
    {
        "anchor": "Defying the Gibbs Phase Rule: Evidence for an Entropy-Driven Quintuple\n  Point in Colloid-Polymer Mixtures: Using a minimal algebraic model for the thermodynamics of binary rod--polymer\nmixtures, we provide evidence for a quintuple phase equilibrium; an observation\nthat seems to be at odds with the Gibbs phase rule for two-component systems.\nOur model is based on equations of state for the relevant liquid crystal phases\nthat are in quantitative agreement with computer simulations. We argue that the\nappearance of a quintuple equilibrium, involving an isotropic fluid, a nematic\nand smectic liquid crystal, and two solid phases can be reconciled with a\ngeneralized Gibbs phase rule in which the two intrinsic length scales of the\nathermal colloid--polymer mixture act as additional field variables.",
        "positive": "Unjamming dynamics: the micromechanics of a seismic fault model: The unjamming transition of granular systems is investigated in a seismic\nfault model via three dimensional Molecular Dynamics simulations. A two--time\nforce--force correlation function, and a susceptibility related to the system\nresponse to pressure changes, allow to characterize the stick--slip dynamics,\nconsisting in large slips and microslips leading to creep motion. The\ncorrelation function unveils the micromechanical changes occurring both during\nmicroslips and slips. The susceptibility encodes the magnitude of the incoming\nmicroslip."
    },
    {
        "anchor": "Glass transitions of freely suspended polymer films: We present a modified version of our \"sliding model\", where chain arcs,\nbetween two contacts at the surface, may move if all the barriers along the arc\nare weaker than a certain threshold.An important advance of the revised model\nis that the high limiting chain lengths N* observed in the experiments are\nnaturally accoundted for. In this model, a film of thickness h, smaller than\nthe coil size, can show either a \"sandwich\" structure with two mobile sublayers\n(at low temperatures T<T(h)), or a single mobile layer at T>T(h). But the\naccident occurring at T=T(h), does not necessarily coincide with the apparent\nglass transition, determined by the intersection of two tangents in a plot of\nthickness versus temperature.",
        "positive": "Coupled dynamics of flow, microstructure, and conductivity in sheared\n  suspensions: We propose a model for the evolution of the conductivity tensor for a flowing\nsuspension of electrically conductive particles. We use discrete particle\nnumerical simulations together with a continuum physical framework to construct\nan evolution law for the suspension microsutructure during flow. This model is\nthen coupled with a relationship between the microstructure and the electrical\nconductivity tensor. The parameters of the joint model are fit experimentally\nusing rheo- electrical conductivity measurements of carbon black suspensions\nunder flow over a range of shear rates. The model is applied to the case of\nsteady shearing as well as time-varying conductivity of unsteady flow\nexperiments. We find that the model prediction agrees closely with the measured\nexperimental data in all cases."
    },
    {
        "anchor": "Dynamics of end-linked star polymer structures: In this work we focus on the dynamics of macromolecular networks formed by\nend-linking identical polymer stars. The resulting macromolecular network can\nthen be viewed as consisting of spacers which connect branching points (the\ncores of the stars). We succeed in analyzing exactly, in the framework of the\ngeneralized Gaussian model, the eigenvalue spectrum of such networks. As\napplications we focus on several topologies, such as regular networks and\ndendrimers; furthermore, we compare the results to those found for regular\nhyperbranched structures. In so doing, we also consider situations in which the\nbeads of the cores differ from the beads of the spacers. The analytical\nprocedure which we use involves an exact real-space renormalization, which\nallows to relate the star-network to a (much simpler) network, in which each\nstar is reduced to its core. It turns out that the eigenvalue spectrum of the\nstar-polymer structure consists of two parts: One follows in terms of\npolynomial equations from the relaxation spectrum of the corresponding\nrenormalized structure, while the second part involves the motion of the spacer\nchains themselves. Finally, we show exemplarily the situation for copolymeric\ndendrimers, calculate their spectra, and from them their storage and the loss\nmoduli.",
        "positive": "Direct Coupling of Free Diffusion Models to Microscopic Models of\n  Confined Crystal Growth and Dissolution: We couple a free solute diffusion model to a model of crystal surface growth\nrepresented by, but not limited to, a (2 + 1)-dimensional solid-on-solid (SOS)\nmodel confined by a flat surface. We use kinetic Monte Carlo (KMC) with\ndissolution rates based on nearest-neighbor interactions to solve the Master\nequation for the surface dynamics, and we use an offlattice random walk to\nmodel the Fickian diffusion of the solute particles. The two solvers are\ncoupled directly through deposition rates of the free particles calculated\nusing the mean first passage time (MFPT) of deposition that is found to scale\nas $r^{-4}$. Two variants are studied: ignoring (radial) and not ignoring the\nline of sight (pathfinding). Reference models such as uniform concentration\n(random deposition) and lattice diffusion (crystal lattice extended into the\nliquid) are used for comparison. We find that the macroscopic limit of the\nsurface dynamics is reproduced by all models. The free diffusion models produce\na lower equilibrium roughness and a smaller height autocorrelation length than\nthe reference models, and are found to behave very well in tight confinements.\nIt is also demonstrated that lattice diffusion does not work well in tight\nconfinements. The two MFPT models behave very similarly close to equilibrium\nand for dissolution, but becomes increasingly different with increasing surface\ngrowth speed. The model is put to use by simulating a cavity with a flux\nboundary condition at one side. The conclusion is that the new model excels in\nconfinement, and line of sight can in practice be ignored since the dominant\ndeposition sites likely are in line of sight, which minimizes the CPU-time\nneeded in the coupling."
    },
    {
        "anchor": "Reentrant phase behaviour for systems with competition between phase\n  separation and self-assembly: In patchy particle systems where there is competition between the\nself-assembly of finite clusters and liquid-vapour phase separation, reentrant\nphase behaviour is observed, with the system passing from a monomeric vapour\nphase to a region of liquid-vapour phase coexistence and then to a vapour phase\nof clusters as the temperature is decreased at constant density. Here, we\npresent a classical statistical mechanical approach to the determination of the\ncomplete phase diagram of such a system. We model the system as a van der Waals\nfluid, but one where the monomers can assemble into monodisperse clusters that\nhave no attractive interactions with any of the other species. The resulting\nphase diagrams show a clear region of reentrance. However, for the most\nphysically reasonable parameter values of the model, this behaviour is\nrestricted to a certain range of density, with phase separation still\npersisting at high densities.",
        "positive": "Rheological model for the alpha relaxation of glass-forming liquids and\n  its comparison to data for DC704 and DC705: Dynamic shear-modulus data are presented for the two silicone oils DC704 and\nDC705 for frequencies between 1 mHz and 10 kHz at temperatures covering more\nthan five decades of relaxation-time variation. The data are fitted to the\nalpha part of a phenomenological model previously shown to describe well the\ndynamic shear modulus of squalane, which has a large beta process [Hecksher\n\\textit{et al.}, J. Chem. Phys. \\textbf{146}, 154504 (2017)]; that model is\ncharacterized by additivity of the alpha and beta shear compliance and by a\nhigh-frequency decay of the alpha process in proportion to $\\omega^{-1/2}$ in\nwhich $\\omega$ is the angular frequency. The fits of the alpha part of this\nmodel to the DC704 and DC705 data are compared to fits by a Havriliak-Negami\ntype model, the Barlow-Erginsav-Lamb model, and a Cole-Davidson type model. At\nall temperatures the best fit is obtained by the alpha part of the squalane\nmodel. This strengthens the conjecture that so-called $\\sqrt{t}$-relaxation,\nleading to high-frequency decays proportional to $\\omega^{-1/2}$, is a general\ncharacteristic of the alpha relaxation of supercooled liquids [Dyre, Phys. Rev.\nE {\\bf 74}, 021502 (2006); Nielsen \\textit{et al.}, J. Chem. Phys.\n\\textbf{130}, 154508 (2009); Pabst \\textit{et al.}, J. Phys. Chem. Lett.\n\\textbf{12}, 3685 (2021)]."
    },
    {
        "anchor": "Impact of random obstacles on the dynamics of a dense colloidal fluid: Using molecular dynamics simulations we study the slow dynamics of a\ncolloidal fluid annealed within a matrix of obstacles quenched from an\nequilibrated colloidal fluid. We choose all particles to be of the same size\nand to interact as hard spheres, thus retaining all features of the porous\nconfinement while limiting the control parameters to the packing fraction of\nthe matrix, {\\Phi}m, and that of the fluid, {\\Phi}f. We conduct detailed\ninvestigations on several dynamic properties, including the tagged-particle and\ncollective intermediate scattering functions, the mean-squared displacement,\nand the van Hove function. We show the confining obstacles to profoundly impact\nthe relaxation pattern of various quantifiers pertinent to the fluid. Varying\nthe type of quantifier (tagged-particle or collective) as well as {\\Phi}m and\n{\\Phi}f, we unveil both discontinuous and continuous arrest scenarios.\nFurthermore, we discover subdiffusive behavior and demonstrate its close\nconnection to the matrix structure. Our findings partly confirm the various\npredictions of a recent extension of mode-coupling theory to the\nquenched-annealed protocol.",
        "positive": "ATP hydrolysis stimulates large length fluctuations in single actin\n  filaments: Polymerization dynamics of single actin filaments is investigated\ntheoretically using a stochastic model that takes into account the hydrolysis\nof ATP-actin subunits, the geometry of actin filament tips, the lateral\ninteractions between the monomers as well as the processes at both ends of the\npolymer. Exact analytical expressions are obtained for a mean growth velocity\nand for dispersion in length fluctuations. It is found that the ATP hydrolysis\nhas a strong effect on dynamic properties of single actin filaments. At high\nconcentrations of free actin monomers the mean size of unhydrolyzed ATP-cap is\nvery large, and the dynamics is governed by association/dissociation of\nATP-actin subunits. However, at low concentrations the size of the cap becomes\nfinite, and the dissociation of ADP-actin subunits makes a significant\ncontribution to overall dynamics. Actin filament length fluctuations reach the\nmaximum at the boundary between two dynamic regimes, and this boundary is\nalways larger than the critical concentration. Random and vectorial mechanisms\nof hydrolysis are compared, and it is found that they predict qualitatively\nsimilar dynamic properties. The possibility of attachment and detachment of\noligomers is also discussed. Our theoretical approach is successfully applied\nto analyze the latest experiments on the growth and length fluctuations of\nindividual actin filaments."
    },
    {
        "anchor": "Morphologies and flow patterns in quenching of lamellar systems with\n  shear: We study the behavior of a fluid quenched from the disordered into the\nlamellar phase under the action of a shear flow. The dynamics of the system is\ndescribed by Navier-Stokes and convection-diffusion equations with pressure\ntensor and chemical potential derived by the Brazovskii free-energy. Our\nsimulations are based on a mixed numerical method with Lattice Boltzmann\nequation and finite difference scheme for Navier-Stokes and order parameter\nequations, respectively. We focus on cases where banded flows are observed with\ntwo different slopes for the component of velocity in the direction of the\napplied flow. Close to the walls the system reaches a lamellar order with very\nfew defects and the slope of the horizontal velocity is higher than the imposed\nshear rate. In the middle of the system the local shear rate is lower than the\nimposed one and the system looks as a mixture of tilted lamellae, droplets and\nsmall elongated domains. We refer to this as to a region with a Shear Induced\nStructures (SIS) configuration. The local behavior of the stress shows that the\nsystem with the coexisting lamellar and SIS regions is in mechanical\nequilibrium. This phenomenon occurs, at fixed viscosity, for shear rates under\na certain threshold; when the imposed shear rate is sufficiently large,\nlamellar order develops in the whole system. Effects of different viscosities\nhave been also considered: The SIS region is observed only at low enough\nviscosity. We compare the above scenario with the usual one of shear banding.\nIn particular, we do not find evidence for a plateau of the stress at varying\nimposed shear rates in the region with banded flow. We interpret our results as\ndue to a tendency of the lamellar system to oppose to the presence of the\napplied flow.",
        "positive": "Macromolecular theory of solvation and structure in mixtures of colloids\n  and polymers: The structural and thermodynamic properties of mixtures of colloidal spheres\nand non-adsorbing polymer chains are studied within a novel general\ntwo-component macromolecular liquid state approach applicable for all size\nasymmetry ratios. The dilute limits, when one of the components is at infinite\ndilution but the other concentrated, are presented and compared to field theory\nand models which replace polymer coils with spheres. Whereas the derived\nanalytical results compare well, qualitatively and quantitatively, with\nmean-field scaling laws where available, important differences from ``effective\nsphere'' approaches are found for large polymer sizes or semi-dilute\nconcentrations."
    },
    {
        "anchor": "Bioprotectant glassforming solutions confined in porous silicon\n  nanocapillaries: Glycerol and trehalose-glycerol binary solutions are glass-forming liquids\nwith remarkable bioprotectant properties. In this paper, we address the effects\nof confining of these solutions in straight channels of diameter D=8 nm formed\nby porous silicon. Neutron diffraction and incoherent quasielastic neutron\nscattering are used to reveal the different effects of nanoconfinement and\naddition of trehalose on the intermolecular structure and molecular dynamics of\nthe liquid and glassy phases, on a nanosecond timescale.",
        "positive": "Snap-induced morphing: From a single bistable shell to the origin of\n  shape bifurcation in interacting shells: The bistability of embedded elements provides a natural route through which\nto introduce reprogrammability to elastic meta-materials. One example of this\nis the soft morphable sheet, in which bistable elements that can be snapped up\nor down, are embedded within a soft sheet. The state of the sheet can then be\nprogrammed by snapping particular elements up or down, resulting in different\nglobal shapes. However, attempts to leverage this programmability have been\nlimited by the tendency for the deformations induced by multiple elastic\nelements to cause large global shape bifurcations. We study the root cause of\nthis bifurcation in the soft morphable sheet by developing a detailed\nunderstanding of the behaviour of a single bistable element attached to a flat\n'skirt' region. We study the geometrical limitations on the bistability of this\nsingle element, and show that the structure of its deformation can be\nunderstood using a boundary layer analysis. Moreover, by studying the\ncompressive strains that a single bistable element induces in the surrounding\nskirt we show that the shape bifurcation in the soft morphable sheet can be\ndelayed by an appropriate design of the lattice on which bistable elements are\nplaced."
    },
    {
        "anchor": "Polymer translocation through pores with complex geometries: We propose a method for the theoretical investigation of polymer\ntranslocation through composite pore structures possessing arbitrarily\nspecified geometries. Translocation through each constituent part of the\ncomposite is treated as being analogous to the diffusion of the translocation\ncoordinate over the free energy landscape derived from the chain configurations\nwithin the pore. The proposed method accounts for possible reverse motions of\nthe leading chain end at the interface between constituent parts of a composite\npore, a possibility that has been neglected in prior studies. As an\nillustration of our method, we study the translocation of a Gaussian chain\nbetween two spherical compartments connected by a cylindrical pore, and by a\ncomposite pore consisting of two connected cylinders of different diameters,\nwhich is structurally similar to the $\\alpha$-hemolysin membrane channel. We\ndemonstrate that reverse chain motions between the pore constituents may\ncontribute significantly to the total translocation time. Our results further\nestablish that translocation through a two-cylinder composite pore is faster\nwhen the chain is introduced into the pore on the cis (wide) side of the\nchannel rather than the trans (narrow) side.",
        "positive": "Local ice-like structure at the liquid water surface: Experiments and computer simulations have established that liquid water's\nsurfaces can deviate in important ways from familiar bulk behavior. Even in the\nsimplest case of an air-water interface, distinctive layering, orientational\nbiases, and hydrogen bond arrangements have been reported, but an overarching\npicture of their origins and relationships has been incomplete. Here we show\nthat a broad set of such observations can be understood through an analogy with\nthe basal face of crystalline ice. Using simulations, we specifically\ndemonstrate that water and ice surfaces share a set of structural features\nsuggesting the presence of nanometer-scale ice-like domains at the air-water\ninterface. Most prominent is a shared characteristic layering of molecular\ndensity and orientation perpendicular to the interface. Similarities in\ntwo-point correlations of hydrogen bond network geometry point to shared\nice-like intermolecular structure in the parallel direction as well. Our\nresults bolster and significantly extend previous conceptions of ice-like\nstructure at the liquid's boundary, and suggest that the much-discussed\nquasi-liquid layer on ice evolves subtly above the melting point into a\nquasi-ice layer at the surface of liquid water."
    },
    {
        "anchor": "Tortuosity in the Brick and Mortar Model Based on Chemical Conduction: Diffusion is a reoccurring phenomena in many fields and is affected by the\ngeometry in which it takes place. Here we investigate the effects of geometry\non diffusion in a Brick and Mortar model system. The tortuous effects are\nevaluated based on generalized Fick's law, i.e. diffusion driven by differences\nin chemical potential. The presented formalism gives a general (semi-)exact\nanalytic expression for the tortuosity using impermeable Bricks, which is\nsuccessfully validated against standard techniques and finite element method\nresults. The approach allows for anisotropic properties of the Mortar, which we\nshow can be significant and is not captured with known analytic techniques.\nBased on the introduced concept of chemical conductivity we also find\ngeneralized Fick's law consistent with Ohm's and Fourier's law in terms of\ntheir constituent parts, which further makes the main results for brick and\nmortar structures directly applicable to diffusion of either charge, heat, or\nmass.",
        "positive": "Redundancy and cooperativity in the mechanics of compositely crosslinked\n  filamentous networks: The actin cytoskeleton in living cells has many types of crosslinkers. The\nmechanical interplay between these different crosslinker types is an open issue\nin cytoskeletal mechanics. We develop a framework to study the cooperativity\nand redundancy in the mechanics of filamentous networks with two types of\ncrosslinkers: crosslinkers that allow free rotations of filaments and\ncrosslinkers that do not. The framework consists of numerical simulations and\nan effective medium theory on a percolating triangular lattice. We find that\nthe introduction of angle-constraining crosslinkers significantly lowers the\nfilament concentrations required for these networks to attain mechanical\nintegrity. This cooperative effect also enhances the stiffness of the network\nand suppresses non-affine deformations at a fixed filament concentration. We\nfurther find that semiflexible networks with only freely-rotating crosslinks\nare mechanically very similar to compositely crosslinked flexible networks with\nboth networks exhibiting the same scaling behavior. We show that the network\nmechanics can either be redundant or cooperative depending on the relative\nenergy scale of filament bending to the energy stored in the angle-constraining\ncrosslinkers, and the relative concentration of crosslinkers. Our results may\nhave implications for understanding the role of multiple crosslinkers even in a\nsystem without bundle formation or other structural motifs."
    },
    {
        "anchor": "Dynamic solid surface tension causes droplet pinning and depinning: The contact line of a liquid drop on a solid exerts a nanometrically sharp\nsurface traction. This provides an unprecedented tool to study highly localised\nand dynamic surface deformations of soft polymer networks. One of the\noutstanding problems in this context is the stick-slip instability, observed\nabove a critical velocity, during which the contact line periodically depins\nfrom its own wetting ridge. Time-resolved measurements of the solid deformation\nare challenging, and the mechanism of dynamical depinning has remained elusive.\nHere we present direct visualisations of the dynamic wetting ridge formed by\nwater spreading on a PDMS gel. Unexpectedly, it is found that the opening angle\nof the wetting ridge increases with speed, which cannot be attributed to bulk\nrheology, but points to a dynamical increase of the solid's surface tensions.\nFrom this we derive the criterion for depinning that is confirmed\nexperimentally. Our findings reveal a deep connection between stick-slip\nprocesses and newly identified dynamical surface effects.",
        "positive": "Spontaneous knotting and unknotting of flexible linear polymers:\n  equilibrium and kinetic aspects: We report on a computational study of the statics and dynamics of long\nflexible linear polymers that spontaneously knot and unknot. Specifically, the\nequilibrium self-entanglement properties, such as the knotting probability,\nknot length and position, are investigated with extensive Monte Carlo sampling\nof chains of up to 15,000 beads. Tens of such equilibrated chains of up to 4,\n096 beads are next used as starting points for Langevin dynamics simulations.\nThe complex interplay of chain dynamics and self-knotting is addressed by\nmonitoring the time evolution of various metric and entanglement properties. In\nparticular, the extensive duration of the simulations allows for observing the\nspontaneous formation and disappearance of prime and composite physical knots\nin linear chains. Notably, a sizeable fraction of self-knotting and unknotting\nevents is found to involve regions that are far away from the chain termini. To\nthe best of our knowledge this represents the first instance where spontaneous\nchanges in knotting for linear homopolymers are systematically characterized\nusing unbiased dynamics simulations."
    },
    {
        "anchor": "How to capture active particles: For many applications, it is important to catch collections of autonomously\nnavigating microbes and man-made microswimmers in a controlled way. Here we\npropose an efficient trap to collectively capture self-propelled colloidal\nrods. By means of computer simulation in two dimensions, we show that a static\nchevron-shaped wall represents an optimal boundary for a trapping device. Its\ncatching efficiency can be tuned by varying the opening angle of the trap. For\nincreasing angles, there is a sequence of three emergent states corresponding\nto partial, complete, and no trapping. A trapping `phase diagram' maps out the\ntrap conditions under which the capture of self-propelled particles at a given\ndensity is rendered optimal.",
        "positive": "Entropy Basis for the Thermodynamic Scaling of the Dynamics of OTP: Structural relaxation times and viscosities for non-associated liquids and\npolymers are a unique function of the product of temperature, T, times specific\nvolume, V, with the latter raised to a constant, g_tau. Similarly, for both\nneat o-terphenyl (OTP) and a mixture the entropy for different T and pressures,\nP, collapse to a single curve when expressed versus TV^g_s, with the scaling\nexponent for the entropy, g_s, essentially equal to the thermodynamic Gruneisen\nparameter. Since the entropy includes contributions from motions, such as\nvibrations and secondary relaxations, which do not affect structural\nrelaxation, g_s < g_tau. We show herein that removal of these contributions\ngives a satisfactory accounting for the magnitude of g_tau. Moreover, the\nrelaxation times of OTP are found to be uniquely defined by the entropy, after\nsubtraction from the latter of a V-independent component."
    },
    {
        "anchor": "Nonlinear dielectric susceptibilities in supercooled liquids: a toy\n  model: The dielectric response of supercooled liquids is phenomenologically modeled\nby a set of Asymmetric Double Wells (ADW), where each ADW contains a dynamical\nheterogeneity of $N_{corr}$ molecules. We find that the linear macroscopic\nsusceptibility $\\chi_1$ does not depend on $N_{corr}$ contrary to all higher\norder susceptibilities $\\chi_{2k+1}$. We show that $\\chi_{2k+1}$ is\nproportional to the $k^{th}$ moment of $N_{corr}$, which could pave the way for\nnew experiments on glass transition. In particular, as predicted by Bouchaud\nand Biroli on general grounds [Phys. Rev. B, {\\bf 72}, 064204 (2005)], we find\nthat $\\chi_3$ is proportional to the average value of $N_{corr}$. We fully\ncalculate $\\chi_3$ and, with plausible values of few parameters our model\naccounts for the salient features of the experimental behavior of $\\chi_3$ of\nsupercooled glycerol.",
        "positive": "Melting and Freezing Lines for a Mixture of Charged Colloidal Spheres\n  with Spindle-Type Phase Diagram: We have measured the phase behavior of a binary mixture of like-charged\ncolloidal spheres with a size ratio of 0.9 and a charge ratio of 0.96 as a\nfunction of particle number density n and composition p. Under exhaustively\ndeionized conditions the aqueous suspension forms solid solutions of body\ncentered cubic structure for all compositions. The freezing and melting lines\nas a function of composition show opposite behavior and open a wide, spindle\nshaped coexistence region. Lacking more sophisticated treatments, we model the\ninteraction in our mixtures as an effective one-component pair energy\naccounting for number weighted effective charge and screening constant. Using\nthis description, we find that within experimental error the location of the\nexperimental melting points meets the range of melting points predicted for\nmonodisperse, one component Yukawa systems made in several theoretical\napproaches. We further discuss that a detailed understanding of the exact phase\ndiagram shape including the composition dependent width of the coexistence\nregion will need an extended theoretical treatment."
    },
    {
        "anchor": "Tracer Dynamics in Crowded Active-Particle Suspensions: We derive equations of motion for the mean-squared displacement (MSD) of an\nactive Brownian particle (ABP) in a crowded environment modeled by a dense\nsystem of passive Brownian particles, and of a passive tracer particle in a\ndense active-Brownian particle system, using a projection-operator scheme. The\ninteraction of the tracer particle with the dense host environment gives rise\nto strong memory effects. Evaluating these approximately in the framework of a\nrecently developed mode-coupling theory for the glass transition in active\nBrownian particles (ABP-MCT), we discuss the various regimes of\nactivity-induced super-diffusive motion and density-induced sub-diffusive\nmotion. The predictions of the theory are shown to be in good agreement with\nresults from an event-driven Brownian dynamics simulation scheme for the\ndynamics of two-dimensional active Brownian hard disks.",
        "positive": "Sequence transferable coarse-grained model of amphiphilic copolymer: Polymer properties are inherently multi-scale in nature, where delicate local\ninteraction details play a key role in describing their global conformational\nbehavior. In this context, deriving coarse-grained (CG) multi-scale models for\npolymeric liquids is a non-trivial task. Further complexities arise when\ndealing with copolymer systems with varying microscopic sequences, especially\nwhen they are of an amphiphilic nature. In this work, we derive a segment-based\ngeneric CG model for amphiphilic copolymers consisting of repeat units of\nhydrophobic (methylene) and hydrophilic (ethylene oxide) monomers. The system\nis a simulation analogue of polyacetal copolymers [Samanta et al.,\nMacromolecules 49, 1858 (2016)]. The CG model is found to be transferable over\na wide range of copolymer sequences and also to be consistent with existing\nexperimental data."
    },
    {
        "anchor": "One-dimensional transport in polymer nanofibers: We report our transport studies in quasi one-dimensional (1D) conductors -\nhelical polyacetylene fibers doped with iodine and the data analysis for other\npolymer single fibers and tubes. We found that at 30 K < T < 300 K the\nconductance and the current-voltage characteristics follow the power law: G(T)\n~ T^alpha with alpha ~ 2.2-7.2 and I(V) ~ V^betta with betta ~ 2-5.7. Both G(T)\nand I(V) show the features characteristic of 1D systems such as Luttinger\nliquid or Wigner crystal. The relationship between our results and theories for\ntunneling in 1D systems is discussed.",
        "positive": "Dynamic Monte Carlo Simulations of Inhomogeneous Colloidal Suspensions: The Dynamic Monte Carlo (DMC) method is an established molecular simulation\ntechnique for the analysis of the dynamics in colloidal suspensions. An\nexcellent alternative to Brownian Dynamics or Molecular Dynamics simulation,\nDMC is applicable to systems of spherical and/or anisotropic particles and to\nequilibrium or out-of-equilibrium processes. In this work, we present a\ntheoretical and methodological framework to extend DMC to the study of\nheterogeneous systems, where the presence of an interface between coexisting\nphases introduces an additional element of complexity in determining the\ndynamic properties. In particular, we simulate a Lennard-Jones fluid at the\nliquid-vapor equilibrium and determine the diffusion coefficients in the bulk\nof each phase and across the interface. To test the validity of our DMC\nresults, we also perform Brownian Dynamics simulations and unveil an excellent\nquantitative agreement between the two simulation techniques."
    },
    {
        "anchor": "High-resolution three-dimensional imaging of topological textures in\n  single-diamond networks: Highly periodic structures are often said to convey the beauty of nature.\nHowever, most material properties are strongly influenced by the defects they\ncontain. On the mesoscopic scale, molecular self-assembly exemplifies this\ninterplay; thermodynamic principles determine short-range order, but long-range\norder is mainly impeded by the kinetic history of the material and by thermal\nfluctuations. For the development of self-assembly technologies, it is\nimperative to characterise and understand the interplay between self-assembled\norder and defect-induced disorder. Here we used synchrotron-based hard X-ray\nnanotomography to reveal a pair of extended topological defects within a\nself-assembled single-diamond network morphology. These defects are\nmorphologically similar to the comet and trefoil patterns of equal and opposite\nhalf-integer topological charges observed in liquid crystals and appear to\nmaintain a constant separation across the thickness of the sample, resembling\npairs of full vortices in superconductors and other hard condensed matter\nsystems. These results are expected to open new windows to study defect\nformation in soft condensed matter, particularly in biological systems where\nmost structures are formed by self-assembly.",
        "positive": "Static self-induced heterogeneity in glass-forming liquids: Overlap as a\n  microscope: We propose and numerically implement a local probe of the static self-induced\nheterogeneity characterizing glass-forming liquids. The method relies on the\nequilibrium statistics of the overlap between pairs of configurations measured\nin mesoscopic cavities with unconstrained boundaries. By systematically\nchanging the location of the probed cavity, we directly detect spatial\nvariations of the overlap fluctuations. We provide a detailed analysis of the\nstatistics of a local estimate of the configurational entropy and we infer an\nestimate of the surface tension between amorphous states, ingredients that are\nboth at the basis of the random first-order transition theory of glass\nformation. Our results represent the first direct attempt to visualize and\nquantify the self-induced heterogeneity underpinning the thermodynamics of\nglass formation. They pave the way for the development of coarse-grained\neffective theories and for a direct assessment of the role of thermodynamics in\nthe activated dynamics of deeply supercooled liquids."
    },
    {
        "anchor": "Numerical investigation of the influence of the history on the local\n  structure of glasses: By means of molecular dynamics simulations and the Voronoi tessellation, we\nstudy the influence of the history on the low temperature characteristics of\nsoft sphere and silica glasses. The quench from the liquid is interrupted at an\nintermediate temperature $T_i$ for a given relaxation time, and then the\ncooling process is continued down to 0K. The local structure at 0K depends on\nthe temperature $T_i$ and the effect is larger for $T_i$ close to the glass\ntransition temperature $T_g$. This dependence, coherent with recent results, is\nexpected in the strong glass former where the characteristics of a particular\nstate depend on its history. In the soft-sphere case, because of\ncrystallization effects, the dependence of the local structure of the glassy\nsamples on their history can only be detected in the supercooled liquid region.",
        "positive": "Frustration of nanoconfined liquid crystals due to hybrid substrate\n  anchoring: We present Monte Carlo simulations of liquid-crystalline material confined to\na nanoscopic slit-pore. The simulations are carried out under isothermal\nconditions in a specialized isostress ensemble in which N fluid molecules are\nexposed to a compressional stress acting on the fluid in directions parallel\nwith the substrate planes. Fluid-fluid and fluid-substrate interactions are\nmodelled as in our previous work [M. Greschek et al., Soft Matter, 2010,\nDOI:10.1039/B924417D). We study several anchoring mechanisms at the solid\nsubstrate by introducing an anchoring function (0<g(u)<1) that depends on the\norientation of a fluid molecule relative to the substrate plane; g(u)\n\"switches\" the fluid-substrate attraction on or off. Here we focus on various\nheterogeneous (i.e., hybrid) anchoring scenarios imposing different anchoring\nfunctions at the opposite substrates. As in our previous study we compute the\nisostress heat capacity which allows us to identify states at which the\nconfined fluid undergoes a structural transformation. The isotropic-nematic\ntransformation turns out to be nearly independent of the specific anchoring\nscenario. This is because the director in the nematic phase assumes a direction\nthat is a compromise between the directions enforced by the competing anchoring\nscenarios at either substrate. On the contrary, at lower compressional stresses\nmolecules prealign in specific directions that depend on details of the\nanchoring scenario."
    },
    {
        "anchor": "End exclusion zones in strongly stretched, molten polymer brushes of\n  arbitrary shape: Theories of strongly stretched polymer brushes, particularly the parabolic\nbrush theory, are valuable for providing analytically tractable predictions for\nthe thermodynamic behavior of surface-grafted polymers in a wide range of\nsettings. However, the parabolic brush limit fails to describe polymers grafted\nto convex, curved substrates, such as the surfaces of spherical nanoparticles\nor the interfaces of strongly segregated block copolymers. It has been\npreviously shown that strongly-stretched, curved brushes require a boundary\nlayer devoid of free chain ends, requiring modifications of the theoretical\nanalysis. While this \"end exclusion zone\" has been successfully incorporated\ninto descriptions of brushes grafted onto the outer surfaces of cylinders and\nspheres, the behavior of brushes on surfaces of arbitrary curvature has not yet\nbeen studied. We present a formulation of the strong-stretching theory for\nmolten brushes on surfaces of arbitrary curvature and identify four distinct\nregimes of interest for which brushes are predicted to possess end exclusion\nzones, notably including regimes of positive mean curvature but negative\nGaussian curvature. Through numerical solutions of the strong-stretching brush\nequations, we report predicted scaling of the size of the end exclusion zone,\nthe chain end distribution, the chain polarization, and the free energy of\nstretching with mean and Gaussian surface curvatures. Through these results, we\npresent a comprehensive picture of how brush geometry influences the end\nexclusions zones and exact strong-stretching free energies, which can be\napplied, for example, to model the full spectrum of brush geometries\nencountered in block copolymer melt assembly.",
        "positive": "In search of invariants for viscous liquids in the density scaling\n  regime: Investigations of dynamic and thermodynamic moduli: In this paper, we report on nontrivial results of our investigations of\ndynamic and thermodynamic moduli in search of invariants for viscous liquids in\nthe density scaling regime by using selected supercooled van der Waals liquids\nas representative materials. Previously, the dynamic modulus $M_{p-T}$ (defined\nin the pressure-temperature representation by the ratio of isobaric activation\nenergy and activation volume) as well as the ratio $B_{T}/M_{p-T}$ (where $B_T$\nis the thermodynamic modulus defined as the inverse isothermal compressibility)\nhave been suggested as some kind of material constants. We have established\nthat they are not valid in the explored wide range of temperatures $T$ over\ndozen decades of structural relaxation times $\\tau $. The temperature\ndependences of $M_{p-T}$ and $B_T/M_{p-T}$ have been elucidated by comparison\nwith the well-known measure of the relative contribution of temperature and\ndensity fluctuations to molecular dynamics near the glass transition, i.e., the\nratio of the isochoric and isobaric activation energies,\n$E^{act}_{V}/E^{act}_{p}$. Then, we have implemented an idea to transform the\ndefinition of the dynamic modulus $M_{p-T}$ from the p-T representation to the\nV-T one. This idea relied on the disentanglement of combined temperature and\ndensity fluctuations involved in isobaric parameters has resulted in finding an\ninvariant for viscous liquids in the density scaling regime, which is the ratio\nof the thermodynamic and dynamic moduli, $B_{T}/M_{V-T}$. In this way, we have\nconstituted a characteristic of thermodynamics and molecular dynamics, which\nremains unchanged in the supercooled liquid state for a given material, the\nmolecular dynamics of which obeys the power density scaling law."
    },
    {
        "anchor": "Equilibrium and out-of-equilibrium dynamics in a molecular layer of\n  azopolymer floating on water studied by Interfacial Shear Rheology: We report the details of the construction and calibration of an ultra\nsensitive surface rheometer, inspired by the setup described in [C.F. Brooks et\nal Langmuir 15, 2450 (1999)], which makes use of high resolution video tracking\nof the motion of a floating magnetized needle and is capable of measuring the\nviscoelastic response of a Langmuir monolayer with an accuracy of 10^-5 N/m.\nThis instrument is then employed for the rheological characterization of a\nLangmuir monolayer of a photosensitive azobenzene polymer, which can be brought\nout of equilibrium by a suitable photoperturbation. The complex dynamic shear\nmodulus G= G' + i G\" is measured as a function of temperature and illumination\npower and wavelength. The reversible rheological ch anges induced in the film\nby photo-perturbation are monitored during time, observing a transition from a\npredominantly elastic (G' > G'') to a viscoelastic (G' \\approx G'') regime.\nThese results are confirmed by comparison with independent measurements\nperformed by us using other rheological techniques. Finally a discussion is\nmade, taking into account the results of a recent x-ray photon correlation\nspectroscopy experiment on the same polymer in equilibrium and out of\nequilibrium.",
        "positive": "Hydrodynamic lift of a two-dimensional liquid domain with odd viscosity: We discuss hydrodynamic forces acting on a two-dimensional liquid domain that\nmoves laterally within a supported fluid membrane in the presence of odd\nviscosity. Since active rotating proteins can accumulate inside the domain, we\nfocus on the difference in odd viscosity between the inside and outside of the\ndomain. Taking into account the momentum leakage from a two-dimensional\nincompressible fluid to the underlying substrate, we analytically obtain the\nfluid flow induced by the lateral domain motion, and calculate the drag and\nlift forces acting on the moving liquid domain. In contrast to the passive case\nwithout odd viscosity, the lateral lift arises in the active case only when the\nin/out odd viscosities are different. The in/out contrast in the odd viscosity\nleads to nonreciprocal hydrodynamic responses of an active liquid domain."
    },
    {
        "anchor": "Kinetics of Surfactant Adsorption: The Free Energy Approach: We review the free energy approach to the kinetics of surfactant adsorption\nat fluid/fluid interfaces. The formalism is applied to several systems. For\nnon-ionic surfactant solutions the results coincide with previous models while\nindicating their limits of validity. We study the case of surfactant mixtures,\nfocusing on the relation between the mixture kinetics and the properties of its\nindividual constituents. Strong electrostatic interactions in salt-free ionic\nsurfactant solutions drastically modify the adsorption kinetics. In this case\nthe theory accounts for experimental results which could not be previously\nunderstood. The effect of screening by added salt is studied as well. Our\ntheoretical predictions are compared with available experiments.",
        "positive": "Filaments in the TGBA phase: A model of filaments of the TGBA phase arising from the homeotropic smectic A\nphase and nucleating on the sample surface is proposed. The model is based on\nthe concept of finite blocks of parallel smectic layers forming a helical\nstructure. The blocks are surrounded by dislocation loops. The model describes\nthe filament structure near the sample surface and explains the observed\ninclination of the filament axis with respect to the easy direction of the\nmolecular anchoring on the surface. The model is based on the observations of\nfilament textures of the TGBA phase in a new chiral liquid crystalline\ncompound, but can be applied for forming of TGBA filaments in any compound. The\ncompression modulus of the compound has been estimated using such parameters as\nanchoring energy, estimated from the field necessary to transform the structure\ninto the homeotropic smectic A, and the observed filament width."
    },
    {
        "anchor": "Active Microrheology in Active Matter Systems: Mobility, Intermittency\n  and Avalanches: We examine the mobility and velocity fluctuations of a driven particle moving\nthrough an active matter bath of self-mobile disks for varied density or area\ncoverage and varied activity. We show that the driven particle mobility can\nexhibit non-monotonic behavior that is correlated with distinct changes in the\nspatial-temporal structures that arise in the active media. We demonstrate that\nthe probe particle velocity distributions exhibit specific features in the\ndifferent dynamic regimes, and identify an activity-induced uniform\ncrystallization that occurs for moderate activity levels and that is distinct\nfrom the previously observed higher activity cluster phase. The velocity\ndistribution in the cluster phase has telegraph noise characteristics produced\nwhen the probe particle moves alternately through high mobility areas that are\nin the gas state and low mobility areas that are in the dense phase. For higher\ndensities and large activities, the system enters what we characterize as an\nactive jamming regime. Here the probe particle moves in intermittent jumps or\navalanches which how power-law distributed sizes that are similar to the\navalanche distributions observed for non-active disk systems near the jamming\ntransition.",
        "positive": "Partition function of a bubble formed in double stranded DNA: We calculate the entropic part of partition function of a bubble embedded in\na double stranded DNA (dsDNA) by considering the total weights of possible\nconfigurations of a system of two single stranded DNA (ssDNA) of given length\nwhich start from a point along the contour of dsDNA and reunite at a position\nvector {\\bf r} measured from the first point and the distribution function of\nthe position vector {\\bf r} which separates the two zipper forks of the bubble\nin dsDNA. For the distribution function of position vector {\\bf r} we use the\ndistribution of the end-to-end vector {\\bf r} of strands of given length of\ndsDNA found from the wormlike chain model. We show that when the chains forming\nthe bubble are assumed to be Gaussian the so called loop closure exponent $c$\nis 3 and when we made correction by including self avoidence in each chain the\nvalue of $c$ becames 3.2."
    },
    {
        "anchor": "A New Paradigm Integrating the Concepts of Particle Abrasion and\n  Breakage: This paper introduces a new paradigm that integrates the concepts of particle\nabrasion and breakage. Both processes can co-occur under loading as soil\nparticles are subjected to friction as well as collisions between particles.\nTherefore, the significance of this integrating paradigm lies in its ability to\naddress both abrasion and breakage in a single framework. The new paradigm is\nmapped out in a framework called the 'particle geometry space.' The x-axis\ncorresponds to the surface-area-to-volume ratio ($A/V$), while the y-axis\nrepresents volume ($V$). This space facilitates a holistic characterization of\nthe four-particle geometry features, i.e., shape (${\\beta}$) and size ($D$) as\nwell as surface area ($A$) and volume ($V$). Three distinct paths (abrasion,\nbreakage, and equally-occurring abrasion and breakage processes), three limit\nlines (breakage line, sphere line, and average shape-conserving line), and five\ndifferent zones are defined in the particle geometry space. Consequently, this\napproach enables us to systematically relate the extent of co-occurring\nabrasion and breakage to the particle geometry evolution.",
        "positive": "Counter-intuitive results in acousto-elasticity: We present examples of body wave and surface wave propagation in deformed\nsolids where the slowest and the fastest waves do not travel along the\ndirections of least and greatest stretch, respectively. These results run\ncounter to commonly accepted theory, practice, and implementation of the\nprinciples of acousto-elasticity in initially isotropic solids. For instance we\nfind that in nickel and steel, the fastest waves are along the direction of\ngreatest compression, not greatest extension (and vice-versa for the slowest\nwaves), as soon as those solids are deformed. Further, we find that when some\nmaterials are subject to a small-but-finite deformations, other extrema of wave\nspeeds appear in non-principal directions. Examples include nickel, steel,\npolystyrene, and a certain hydrogel. The existence of these ``oblique'',\nnon-principal extremal waves complicates the protocols for the non-destructive\ndetermination of the directions of extreme strains."
    },
    {
        "anchor": "Marginal intermediate statistics in the excited spectra of E\\otimes\n  (b_1+b_2) Jahn-Teller systems: The long-range spectral density correlations (spectral rigidities\n$\\bar{\\Delta}_3(\\bar n)$ and related spectral compressibilities) of the\n$E\\otimes (b_1+b_2)$ Jahn-Teller model are found strongly nonuniversal with\nrespect to the Hamiltonian parameters and inhomogeneous with respect to the\nchoice of a partial energy segment. However, the spectral compressibilities\nfound for the partial spectral segments and averaged over a whole relevant part\nof the spectrum cumulate close to a well-defined limit pertaining to the\nsemi-Poisson statistics. This is in accordance with similar tendencies revealed\nin the short-range averaged statistical characteristics of this model\ninvestigated in our previous paper [1]. We ascribe the nonuniversal and\ninhomogeneous nonintegrability behaviour to the changing degree of the\nbrokening of the rotation symmetry when changing parameters of our effectively\ntwo-dimensional model. It results in a random distribution of the respective\nlocalized wave functions at all scales up to the size of an available state\nspace. The multifractal behaviour of the wave functions is implied from the\nanalysis of their (averaged) fractal dimensions which range up to $1.5\\pm 0.1$\n(for $\\bar{D}_2$). This might imply the concept of the chaos-assisted\ntunnelling between the regions of reduced degree of stochasticity through\nregions of high degree of stochasticity. It supports the analogy with the\ntwo-dimensional Anderson model with marginal-asymptotically far metal-insulator\ntransition. The features found allow us to classify the present model as a\nmember of the class with a multifractal eigenfunction statistics characteristic\nfor the spectra with weakened level repulsion similar to the Anderson model\nclose to the metal-insulator transition.",
        "positive": "Anisotropic Young-Laplace-equation provides insight into tissue growth: Growing tissues are highly dynamic, flowing on sufficiently long time-scales\ndue to cell proliferation, migration and tissue remodeling. As a consequence,\nliving tissues can be approximated as liquids. This means the shape of\nmicrotissues is governed by a surface stress state as in fluid droplets. Recent\nwork showed that cells in the near-surface region of fibroblastic or\nosteoblastic microtissues contract with highly oriented actin filaments, thus\nmaking the surface stress state anisotropic, in contrast to what is expected\nfor an isotropic fluid. Here, we extend the Young-Laplace law to include\nmechanical anisotropy of the surface. We then take this into account to\ndetermine equilibrium shapes of rotationally symmetric bodies subjected to\nanisotropic surface stress states and derive a family of surfaces of revolution\nin analogy to the Delaunay surfaces. A comparison with recently published\nshapes of microtissues shows that this theory accurately predicts both the\nsurface shape and the direction of the actin filaments in the surface. The\nanisotropic version of the Young-Laplace law might help describing the growth\nof microtissues and also predicts the shape of fluid bodies with highly\nanisotropic surface properties."
    },
    {
        "anchor": "Anomaly of the non-ergodicity parameter and crossover to white noise in\n  the fast relaxation spectrum of a simple glass former: We present quasi-elastic light scattering (LS) and dielectric (DS) spectra of\nthe glass former alpha-picoline (13K < T < 320K). At high temperatures the\nevolution of the susceptibility minimum is well described by mode coupling\ntheory (MCT) yielding a critical temperature T_c = 162K +- 5K. At T_c > T > T_g\nthe excess wing of the alpha-process identified in the DS spectra and\ncharacterized by a power-law exponent c is rediscovered in the LS spectra.\nIntroducing a universal evolution for c = c[lg(tau_{alpha})] as suggested by DS\ndata of several glass formers, the fast dynamics spectrum is singled out,\nallowing to determine the non-ergodicity parameter f(T). The latter shows the\npredicted cusp-like anomaly identifying T_c as well. Another discontinuous\nchange of f(T) is observed at T_g. The fast dynamics spectra exhibit a\ncrossover to ``white noise'' (T < T_c). Concerning the fast dynamics, we\nconclude that idealized MCT predictions hold even below T_c.",
        "positive": "Orientational transition in nematic liquid crystals under oscillatory\n  Poiseuille flow: We investigate the orientational behaviour of a homeotropically aligned\nnematic liquid crystal subjected to an oscillatory plane Poiseuille flow\nproduced by an alternating pressure gradient. For small pressure amplitudes the\ndirector oscillates within the flow plane around the initial homeotropic\nposition, whereas for higher amplitudes a spatially homogeneous transition to\nout-of-plane director motion was observed for the first time. The orientational\ntransition was found to be supercritical and the measured frequency dependence\nof the critical pressure amplitude in the range between 2 and 20 Hz was in\nquantitative agreement with a recent theory."
    },
    {
        "anchor": "Interplay between Kinetics and Dynamics of Liquid-Liquid Phase\n  Separation in a Protein Solution Revealed by Coherent X-ray Spectroscopy: Microscopic dynamics of complex fluids in the early stage of spinodal\ndecomposition (SD) is strongly intertwined with the kinetics of structural\nevolution, which makes a quantitative characterization challenging. In this\nwork, we use x-ray photon correlation spectroscopy to study the dynamics and\nkinetics of a protein solution undergoing liquid-liquid phase separation\n(LLPS). We demonstrate that in the early stage of SD, the structural relaxation\nkinetics is up to 40 times slower than the dynamics and thus can be decoupled.\nThe kinetic decay rate is inversely proportional to time in the early stage,\nfollowed by a nearly constant behavior during the coarsening stage. The\nmicroscopic dynamics can be well described by hyper-diffusive ballistic motions\nwith a relaxation time exponentially growing with time in the early stage\nfollowed by a power-law increase with fluctuations. These experimental results\nare further supported by simulations based on the Cahn-Hilliard equation. The\nestablished framework is applicable to other condensed matter and biological\nsystems undergoing phase transitions and may also inspire further theoretical\nwork.",
        "positive": "Self-Dual Bending Theory for Vesicles: We present a self-dual bending theory that may enable a better understanding\nof highly nonlinear global behavior observed in biological vesicles. Adopting\nthis topological approach for spherical vesicles of revolution allows us to\ndescribe them as frustrated sine-Gordon kinks. Finally, to illustrate an\napplication of our results, we consider a spherical vesicle globally distorted\nby two polar latex beads."
    },
    {
        "anchor": "Persistent motion of a Brownian particle subject to repulsive feedback\n  with time delay: Based on analytical and numerical calculations we study the dynamics of an\noverdamped colloidal particle moving in two dimensions under time-delayed,\nnon-linear feedback control. Specifically, the particle is subject to a force\nderived from a repulsive Gaussian potential depending on the difference between\nits instantaneous position, $\\mathbf{r}(t)$, and its earlier position\n$\\mathbf{r}(t-\\tau)$, where $\\tau$ is the delay time. Considering first the\ndeterministic case, we provide analytical results for both, the case of small\ndisplacements and the dynamics at long times. In particular, at appropriate\nvalues of the feedback parameters, the particle approaches a steady state with\na constant, non-zero velocity whose direction is constant as well. In the\npresence of noise, the direction of motion becomes randomized at long times,\nbut the (numerically obtained) velocity autocorrelation still reveals some\npersistence of motion. Moreover, the mean-squared displacement (MSD) reveals a\nmixed regime at intermediate times with contributions of both, ballistic motion\nand diffusive translational motion, allowing us to extract an estimate for the\neffective propulsion velocity in presence of noise. We then analyze the data in\nterms of exact, known results for the MSD of active Brownian particles. The\ncomparison indeed indicates a strong similarity between the dynamics of the\nparticle under repulsive delayed feedback and active motion. This relation\ncarries over to the behavior of the long-time diffusion coefficient\n$D_\\mathrm{eff}$ which, similarly to active motion, is strongly enhanced\ncompared to the free case. Finally we show that, for small delays,\n$D_\\mathrm{eff}$ can be estimated analytically.",
        "positive": "Nanoparticle Translocation through Conical Nanopores: A Finite Element\n  Study of Electrokinetic Transport: Recent years have seen a surge of interest in nanopores because such\nstructures show a strong potential for characterizing nanoparticles, proteins,\nDNA, and even single molecules. These systems have been extensively studied in\nexperiment as well as by all-atom and coarse-grained simulations, with a strong\nfocus on DNA translocation. However, the equally interesting problem of\nparticle characterization using nanopores has received far less attention.\nHere, we theoretically investigate the translocation of a nanoparticle through\na conical nanocapillary. We use a model based on numerically solving the\ncoupled system of electrokinetic continuum equations, which we introduce in\ndetail. Based on our findings, we formulate basic guidelines for obtaining the\nmaximum current signal during the translocation event, which should be\ntransferable to other nanopore geometries. In addition, the dependence of the\nsignal strength on particle properties, such as surface charge and size, is\nevaluated. Finally, we identify conditions under which the translocation is\nprevented by the formation of a strong electro-osmotic barrier and show that\nthe particle may even become trapped at the pore orifice, without imposing an\nexternal hydrostatic pressure difference."
    },
    {
        "anchor": "How to impose stick boundary conditions in coarse-grained hydrodynamics\n  of Brownian colloids and semi-flexible fiber rheology: Long-range hydrodynamics between colloidal particles or fibers is modelled by\nthe Fluid Particle Model. Two methods are considered to impose the fluid\nboundary conditions at colloidal surfaces. In the first method radial and\ntransverse friction forces between particle and solvent are applied such that\nthe correct friction and torque follows for moving or rotating particles. The\nforce coefficients are calculated analytically and checked by numerical\nsimulation. In the second method a collision rule is used between colloidal\nparticle and solvent particle that imposes the stick boundary conditions\nexactly. The collision rule comprises a generalisation of the Lowe-Anderson\nthermostat to radial and transverse velocity differences.",
        "positive": "Mean-field models for the chemical fueling of transient soft matter\n  states: The chemical fueling of transient states (CFTS) is a powerful process to\ncontrol the nonequilibrium structuring and the homeostatic function of adaptive\nsoft matter systems. Here, we introduce a mean-field model of CFTS based on the\nactivation of metastable equilibrium states in a tilted Landau bistable energy\nlandscape along a coarse-grained reaction coordinate (or order parameter)\ntriggered by a nonmonotonic two-step chemical fueling reaction. Evaluation of\nthe model in the quasi-static (QS) limit - valid for fast system relaxation -\nallows us to extract useful analytical laws for the critical activation\nconcentration and duration of the transient states in dependence of physical\nparameters, such as rate constants, fuel concentrations, and the system's\ndistance to its equilibrium transition point. We apply our model in the QS\nlimit to recent experiments of CFTS of collapsing responsive microgels and find\na very good performance with only a few global and physically interpretable\nfitting parameters, which can be employed for programmable material design.\nMoreover, our model framework also allows a thermodynamic analysis of the\nenergy and performed work in the system. Finally, we go beyond the QS limit,\nwhere the system's response is slow and retarded versus the chemical reaction,\nusing an overdamped Smoluchowski approach. The latter demonstrates how internal\nsystem time scales can be used to tune the time-dependent behavior and\nprogrammed delay of the transient states in full nonequilibrium."
    },
    {
        "anchor": "Compression of finite size polymer brushes: We consider edge effects in grafted polymer layers under compression. For a\nsemi-infinite brush, the penetration depth of edge effects $\\xi\\propto\nh_0(h_0/h)^{1/2}$ is larger than the natural height $h_0$ and the actual height\n$h$. For a brush of finite lateral size $S$ (width of a stripe or radius of a\ndisk), the lateral extension $u_S$ of the border chains follows the scaling law\n$u_S = \\xi \\phi (S/\\xi)$. The scaling function $\\phi (x)$ is estimated within\nthe framework of a local Flory theory for stripe-shaped grafting surfaces. For\nsmall $x$, $\\phi (x)$ decays as a power law in agreement with simple arguments.\nThe effective line tension and the variation with compression height of the\nforce applied on the brush are also calculated.",
        "positive": "Absence of anomalous underscreening in highly concentrated aqueous\n  electrolytes confined between smooth silica surfaces: Recent experiments and a series of subsequent theoretical studies suggest the\noccurrence of universal underscreening in highly concentrated electrolyte\nsolutions. We performed a set of systematic Atomic Force Spectroscopy\nmeasurements for aqueous salt solutions in a concentration range from 1 mM to 5\nM using chloride salts of various alkali metals as well as mixed concentrated\nsalt solutions (involving both mono- and divalent cations and anions), that\nmimic concentrated brines typically encountered in geological formations.\nExperiments were carried out using flat substrates and submicrometer-sized\ncolloidal probes made of smooth oxidized silicon immersed in salt solutions at\npH values of 6 and 9 and temperatures of 25 {\\deg}C and 45 {\\deg}C. While\nstrong repulsive forces were observed for the smallest tip-sample separations,\nnone of the conditions explored displayed any indication of anomalous long\nrange electrostatic forces as reported for macroscopic mica surfaces. Instead,\nforces are universally dominated by attractive van der Waals interactions at\ntip-sample separations of $\\approx$2nm and beyond for salt concentrations of 1\nM and higher. Complementary calculations based on classical density functional\ntheory for the primitive model support these experimental observations and\ndisplay a consistent decrease in screening length with increasing ion\nconcentration."
    },
    {
        "anchor": "Molecular Dynamics Simulations of Binary Sphere Mixtures: Explicit simulations of fluid mixtures of highly size-dispersed particles are\nconstrained by numerical challenges associated with identifying\npair-interaction neighbors. Recent algorithmic developments have ameliorated\nthese difficulties to an extent, permitting more efficient simulations of\nsystems with many large and small particles of disperse sizes. We leverage\nthese capabilities to perform molecular dynamics simulations of binary sphere\nmixtures with elastically stiff particles approaching the hard sphere limit and\nparticle size ratios of up to 50, approaching the colloidal limit. The systems\nconsidered consist of 500 large particles and up to nearly 3.6 million small\nparticles with total particle volume fractions up to 0.51. Our simulations\nconfirm qualitative predictions for correlations between large particles\npreviously obtained analytically and for simulations employing effective\ndepletion interactions, but also reveal additional insights into the\nnear-contact structure that result from the explicit treatment of the small\nparticle solvent. No spontaneous crystal nucleation was observed during the\nsimulations, suggesting that nucleation rates in the fluid-solid coexistence\nregion are too small to observe crystal nucleation for feasible simulation\nsystem sizes and timescales.",
        "positive": "Influence of Particle Size Distribution on Random Close Packing: The densest amorphous packing of rigid particles is known as random close\npacking. It has long been appreciated that higher densities are achieved by\nusing collections of particles with a variety of sizes. The variety of sizes is\noften quantified by the polydispersity of the particle size distribution: the\nstandard deviation of the radius divided by the mean radius. Several prior\nstudies quantified the increase of the packing density as a function of\npolydispersity. Of course, a particle size distribution is also characterized\nby its skewness, kurtosis, and higher moments, but the influence of these\nparameters has not been carefully quantified before. In this work, we\nnumerically generate many packings with different particle radii distributions,\nvarying polydispersity and skewness independently of one another. We find two\nsignificant results. First, the skewness can have a significant effect on the\npacking density and in some cases can have a larger effect than polydispersity.\nSecond, the packing fraction is relatively insensitive to the value of the\nkurtosis. We present a simple empirical formula for the value of the random\nclose packing density as a function of polydispersity and skewness."
    },
    {
        "anchor": "Density Dependent Cohesion Leads to Controlled Phase Separation in\n  Brownian Suspensions: Mechanical interactions between biological cells may be mediated by secreted\nproducts, making them dependent on the local particle density. Here, we explore\nthe generic physics of density-dependent attractive interactions. We show using\nBrownian dynamics simulations that density-dependent interactions can produce\ninteresting phase separation behaviour including control of aggregate size\nduring a spinodal decomposition-like separation process. We show that these\nresults are generic using continuum modelling of the appropriate Cahn-Hilliard\nequation. Our study suggests that density-dependent interactions can provide a\ngeneric mechanism for control of aggregate size during phase separation.",
        "positive": "Effects of three-body interactions on the structure and thermodynamics\n  of liquid krypton: Large-scale molecular dynamics simulations are performed to predict the\nstructural and thermodynamic properties of liquid krypton using a potential\nenergy function based on the two-body potential of Aziz and Slaman plus the\ntriple-dipole Axilrod-Teller (AT) potential. By varying the strength of the AT\npotential we study the influence of three-body contribution beyond the\ntriple-dipole dispersion. It is seen that the AT potential gives an overall\ngood description of liquid Kr, though other contributions such as higher order\nthree-body dispersion and exchange terms cannot be ignored."
    },
    {
        "anchor": "Twisted domains in ferroelectric nematic liquid crystals: Ferroelectric nematics present properties promising for applications, which\nstrongly depend on the confinement conditions and the presence of defects. In\nthis work, we have observed and analysed textures in the cells with homogeneous\ngeometry for a ferroelectric nematogen. The studied compound reveals the\nferroelectric nematic phase, NF, directly on cooling from the isotropic phase.\nThe NF phase is stable and persists down to the room temperatures. Textures in\nthe homogeneous cell with antiparallel alignment prefer to be arranged in\ntwisted domains with borderlines oriented preferentially in the perpendicular\ndirection with respect to the surface alignment (rubbing direction). We have\ndescribed these domains and developed a model of 2/pi disclinations, which are\nseparating the areas with an opposite twist sense. We discussed the character\nof disclination charge and explained why these disclination lines prefer to be\noriented perpendicularly to the rubbing direction.",
        "positive": "Interacting Brownian particles exhibiting enhanced rectification in an\n  asymmetric channel: Rectification of interacting Brownian particles is investigated in a\ntwo-dimensional asymmetric channel in the presence of an external periodic\ndriving force. The periodic driving force can break the thermodynamic\nequilibrium and induces rectification of particles (or finite average\nvelocity). The spatial variation in the shape of the channel leads to entropic\nbarriers, which indeed control the rectification of particles. We find that by\nsimply tunning the driving frequency, driving amplitude, and shape of the\nasymmetric channel, the average velocity can be reversed. Moreover, a short\nrange interaction force between the particles further enhances the\nrectification of particles greatly. This interaction force is modeled as the\nlubrication interaction. Interestingly, it is observed that there exists a\ncharacteristic critical frequency $\\Omega_c$ below which the rectification of\nparticles greatly enhances in the positive direction with increasing the\ninteraction strength; whereas, for the frequency above this critical value, it\ngreatly enhances in the negative direction with increasing the interaction\nstrength. Further, there exists an optimal value of the asymmetric parameter of\nthe channel for which the rectification of interacting particles is maximum.\nThese findings are useful in sorting out the particles and understanding the\ndiffusive behavior of small particles or molecules in microfluidic channels,\nmembrane pores, etc."
    },
    {
        "anchor": "Power Law Rheology of Folded Protein Hydrogels: Folded protein hydrogels are prime candidates as tuneable biomaterials but it\nis unclear to what extent their mechanical properties have mesoscopic, as\nopposed to molecular origins. To address this, we probe hydrogels of the\nmuscle-derived protein $I27_5$, using a multimodal rheology approach. Across\nmultiple protocols, the hydrogels consistently exhibit power-law\nviscoelasticity in the linear viscoelastic regime with an exponent $\\beta =\n0.03$, suggesting a dense fractal meso-structure, with predicted fractal\ndimension $d_f = 2.48$. In the nonlinear viscoelastic regime, the hydrogel\nundergoes stiffening and energy dissipation, indicating simultaneous alignment\nand unfolding of the folded proteins. Remarkably, this behaviour is highly\nreversible, as the value of $\\beta$, $d_f$ and the viscoelastic moduli return\nto their equilibrium value, even after multiple cycles of deformation. This\nhighlights a previously unrevealed diversity of viscoelastic properties that\noriginate on the mesoscopic scale. These considerations are likely to be key to\ncontrolling the viscoelasticity of folded protein hydrogels.",
        "positive": "Transport coefficients of multi-particle collision algorithms with\n  velocity-dependent collision rules: Detailed calculations of the transport coefficients of a recently introduced\nparticle-based model for fluid dynamics with a non-ideal equation of state are\npresented. Excluded volume interactions are modeled by means of biased\nstochastic multiparticle collisions which depend on the local velocities and\ndensities. Momentum and energy are exactly conserved locally. A general scheme\nto derive transport coefficients for such biased, velocity dependent collision\nrules is developed. Analytic expressions for the self-diffusion coefficient and\nthe shear viscosity are obtained, and very good agreement is found with\nnumerical results at small and large mean free paths. The viscosity turns out\nto be proportional to the square root of temperature, as in a real gas. In\naddition, the theoretical framework is applied to a two-component version of\nthe model, and expressions for the viscosity and the difference in diffusion of\nthe two species are given."
    },
    {
        "anchor": "Bulk structural informations from density functionals for patchy\n  particles: We investigate bulk structural properties of tetravalent associating\nparticles within the framework of classical density functional theory, building\nupon Wertheim's thermodynamic perturbation theory. To this end, we calculate\ndensity profiles within an effective test-particle geometry and compare to\nradial distribution functions obtained from computer simulations. We\ndemonstrate that a modified version of the functional proposed by Yu and Wu [J.\nChem. Phys. 116, 7094 (2002)] based on fundamental measure theory for hard\nspheres produces accurate results, although the functional does not satisfy the\nexactly known low-density limit. However, at low temperatures where particles\nstart to form an amorphous tetrahedral network, quantitative differences\nbetween simulations and theory emerge due to the absence of geometrical\ninformations regarding the patch arrangement in the latter. Indeed, here we\nfind that the theory fits better to simulations of the floating-bond model [J.\nChem. Phys. 127, 174501 (2007)], which exhibits a weaker tetrahedral order due\nto more flexible bonds between particles. We also demonstrate that another\ncommon density functional approach by Segura \\textit{et al.} [Mol. Phys. 90,\n759 (1997)] fails to capture fundamental structural properties.",
        "positive": "Effective interactions between inclusions in an active bath: We study effective two- and three-body interactions between non-active\ncolloidal inclusions in an active bath of chiral or non-chiral particles, using\nBrownian Dynamics simulations within a standard, two-dimensional model of\ndisk-shaped inclusions and active particles. In a non-chiral active bath, we\nfirst corroborate previous findings on effective two-body repulsion mediated\nbetween the inclusions by elucidating the detailed non-monotonic features of\nthe two-body force profiles, including a primary maximum, and a secondary hump\nat larger separations that was not previously reported. We then show that these\nfeatures arise directly from the formation, and sequential overlaps, of\ncircular layers (or 'rings') of active particles around the inclusions, as the\nlatter are brought to small surface separations. These rings extend to radial\ndistances of a few active-particle radii from the surface of inclusions, giving\nthe hard-core inclusions relatively thick, soft, repulsive 'shoulders', whose\nmultiple overlaps then enable significant (non-pairwise) three-body forces in\nboth non-chiral and chiral active baths. The resulting three-body forces can\neven exceed the two-body forces in magnitude and display distinct repulsive and\nattractive regimes at intermediate to large self-propulsion strengths. In a\nchiral active bath, we show that, while active particles still tend to\naccumulate at the immediate vicinity of the inclusions, they exhibit strong\ndepletion from the intervening region between the inclusions, and partial\ndepletion from relatively thick, circular, zones further away from the\ninclusions. In this case, the effective, predominantly repulsive, interactions\nbetween the inclusions turn to active, chirality-induced, depletion-type\nattractions, acting over an extended range of separations."
    },
    {
        "anchor": "Fluctuation-Facilitated Charge Migration along DNA: We propose a model Hamiltonian for charge transfer along the DNA double helix\nwith temperature driven fluctuations in the base pair positions acting as the\nrate limiting factor for charge transfer between neighboring base pairs. We\ncompare the predictions of the model with the recent work of J.K. Barton and\nA.H. Zewail (Proc.Natl.Acad.Sci.USA, {\\bf 96}, 6014 (1999)) on the unusual\ntwo-stage charge transfer of DNA.",
        "positive": "Double-Slit Interferometry with a Bose-Einstein Condensate: A Bose-Einstein \"double-slit\" interferometer has been recently realized\nexperimentally by (Y. Shin et. al., Phys. Rev. Lett. 92 50405 (2004)). We\nanalyze the interferometric steps by solving numerically the time-dependent\nGross-Pitaevski equation in three-dimensional space. We focus on the\nadiabaticity time scales of the problem and on the creation of spurious\ncollective excitations as a possible source of the strong dephasing observed\nexperimentally. The role of quantum fluctuations is discussed."
    },
    {
        "anchor": "A geometrical framework for thinking about proteins: We present a model, based on symmetry and geometry, for proteins. Using\nelementary ideas from mathematics and physics, we derive the geometries of\ndiscrete helices and sheets. We postulate a compatible solvent-mediated\nemergent pairwise attraction that assembles these building blocks, while\nrespecting their individual symmetries. Instead of seeking to mimic the\ncomplexity of proteins, we look for a simple abstraction of reality that yet\ncaptures the essence of proteins. We employ analytic calculations and detailed\nMonte Carlo simulations to explore some consequences of our theory. The\npredictions of our approach are in accord with experimental data. Our framework\nprovides a rationalization for understanding the common characteristics of\nproteins. Our results show that the free energy landscape of a globular protein\nis pre-sculpted at the backbone level, sequences and functionalities evolve in\nthe fixed backdrop of the folds determined by geometry and symmetry, and that\nprotein structures are unique in being simultaneously characterized by\nstability, diversity, and sensitivity.",
        "positive": "Microscopically grounded constitutive model for dense suspensions of\n  soft particles below jamming: We derive from particle-level dynamics a constitutive model describing the\nrheology of two-dimensional dense soft suspensions below the jamming\ntransition, in a regime where hydrodynamic interactions between particles are\nscreened. Based on a statistical description of particle dynamics, we obtain\nthrough a set of physically plausible approximations a non-linear tensorial\nevolution equation for the deviatoric part of the stress tensor, involving the\nstrain-rate and vorticity tensors. This tensorial evolution equation involves\nsingular terms usually not taken into account in phenomenological constitutive\nmodels, which most often assume a regular expansion in terms of the stress\ntensor. All coefficients appearing in the equation have known expressions in\nterms of the microscopic parameters of the model. The predictions of this\nmicroscopically grounded constitutive model have several qualitative features\nthat are specific to the rheology of soft suspensions measured in experiments\nor simulations. The model shows a typical behavior of polymeric visco-elastic\nmaterials, such as normal stress differences quadratic in the shear rate\n$\\dot\\gamma$, as well as typical behaviors of suspensions of stiff particles,\nsuch as a particle pressure linear in $\\dot\\gamma$ and a zero-shear viscosity\ndiverging at the jamming transition. The model also predicts a sharper shear\nthinning than other visco-elastic models at small shear rates, in qualitative\nagreement with experimental observations. Furthermore the shear thinning\nfollows a critical scaling close to the jamming transition."
    },
    {
        "anchor": "Information Bottleneck in Peptide Conformation Determination by X-ray\n  Absorption Spectroscopy: We apply a recently developed technique utilizing machine learning for\nstatistical analysis of computational nitrogen K-edge spectra of aqueous\ntriglycine. This method, the emulator-based component analysis, identifies\nspectrally relevant structural degrees of freedom from a data set filtering\nirrelevant ones out. Thus tremendous reduction in the dimensionality of the\nill-posed nonlinear inverse problem of spectrum interpretation is achieved.\nStructural and spectral variation across the sampled phase space is notable.\nUsing these data, we train a neural network to predict the intensities of\nspectral regions of interest from the structure. These regions are defined by\nthe temperature-difference profile of the simulated spectra, and the analysis\nyields a structural interpretation for their behavior. Even though the utilized\nlocal many-body tensor representation implicitly encodes the secondary\nstructure of the peptide, our approach proves that this information is\nirrecoverable from the spectra. A hard X-ray Raman scattering experiment\nconfirms the overall sensibility of the simulated spectra, but the predicted\ntemperature-dependent effects therein remain beyond the achieved statistical\nconfidence level.",
        "positive": "The critical compressibility factor of fluids from the Global\n  Isomorphism approach: The relation between the critical compressibility factors $Z_{c}$ of the\nLennard-Jones fluid and the Lattice Gas (Ising model) is derived within the\nglobal isomorphism approach. On this basis we obtain the alternative form for\nthe value of the critical compressibility factor which is different from widely\nused phenomenological Timmermans relation. The estimates for the critical\npressure $P_c$ and $Z_c$ of the Lennard-Jones fluid are obtained in case of two\nand three dimensions. The extension of the formalism is proposed to include the\nPitzer's acentric factor into consideration."
    },
    {
        "anchor": "Light control of the flow of phototactic microswimmer suspensions: Some micro-algae are sensitive to light intensity gradients. This property is\nknown as phototaxis: the algae swim toward a light source (positive\nphototaxis). We use this property to control the motion of micro-algae within a\nPoiseuille flow using light. The combination of flow vorticity and phototaxis\nresults in a concentration of algae around the center of the flow. Intermittent\nlight exposure allows analysis of the dynamics of this phenomenon and its\nreversibility. With this phenomenon, we hope to pave the way toward new algae\nconcentration techniques (a bottleneck challenge in hydrogen algal production)\nand toward the improvement of pollutant bio-detector technology.",
        "positive": "Schwinger-Dyson equations for composite electrolytes governed by mixed\n  electrostatic couplings strengths: The electrostatic Schwinger-Dyson equations are derived and solved for an\nelectrolyte mixture composed of mono- and multivalent ions confined to a\nnegatively charged nanoslit. The closure of these equations is based on an\nasymmetric treatment of the ionic species with respect to their electrostatic\ncoupling strength; the weakly coupled monovalent ions are treated within a\ngaussian approximation while the multivalent counterions of high coupling\nstrength are incorporated with a strong-coupling approach. The resulting\nself-consistent formalism includes explicitly the interactions of the\nmultivalent counterions with the monovalent salt. In highly charged membranes\ncharacterized by a pronounced multivalent counterion adsorption, these\ninteractions take over the salt-membrane charge coupling. As a result, the\nincrement of the negative membrane charge brings further salt anions into the\npore and excludes salt cations from the pore into the reservoir. The\ncorresponding like-charge attraction and opposite-charge repulsion effect is\namplified by the pore confinement but suppressed by salt addition into the\nreservoir. The effect is particularly pronounced in high dielectric membranes\nwhere the attractive polarization forces lead to a dense multivalent cation\nlayer at the membrane walls. These cation layers act as an effective positive\nsurface charge, resulting in a total monovalent cation exclusion and a strong\nanion excess even in the case of neutral membrane walls."
    },
    {
        "anchor": "Normal force controlled rheology applied to agar gelation: A wide range of thermoreversible gels are prepared by cooling down to ambient\ntemperature hot aqueous polymer solutions. During the sol-gel transition, such\nmaterials may experience a volume contraction which is traditionally overlooked\nas rheological measurements are usually performed in geometries of constant\nvolume. In this article, we revisit the formation of 1.5\\% wt. agar gels\nthrough a series of benchmark rheological experiments performed with a\nplate-plate geometry. We demonstrate on that particular gel of polysaccharides\nthat the contraction associated with the sol/gel transition cannot be\nneglected. Indeed, imposing a constant gap width during the gelation results in\nthe strain hardening of the sample, as evidenced by the large negative normal\nforce that develops. Such hardening leads to the slow drift in time of the gel\nelastic modulus $G'$ towards ever larger values, and thus to an erroneous\nestimate of $G'$. As an alternative, we show that imposing a constant normal\nforce equals to zero during the gelation, instead of a constant gap width,\nsuppresses the hardening as the decrease of the gap compensates for the sample\ncontraction. Using normal force controlled rheology, we then investigate the\nimpact of thermal history on 1.5\\% wt. agar gels. We show that neither the\nvalue of the cooling rate, nor the introduction of a constant temperature stage\nduring the cooling process influence the gel elastic properties. Instead, $G'$\nonly depends on the terminal temperature reached at the end of the cooling\nramp, as confirmed by direct imaging of the gel microstructure by cryoelectron\nmicroscopy. The present work offers an extensive review of the technical\ndifficulties associated with the rheology of hydrogels and paves the way for a\nsystematic use of normal force controlled rheology to monitor non-isochoric\nprocesses.",
        "positive": "An orbital-free self-consistent field approach for molecular clusters\n  and liquids: We present an ``orbital'' free density functional theory for computing the\nquantum ground state of atomic clusters and liquids. Our approach combines the\nBohm hydrodynamical description of quantum mechanics with an information\ntheoretical approach to determine an optimal quantum density function in terms\nof density approximates to a statistical sample. The ideas of Bayesian\nstatistical analysis and an expectation-maximization procedure are combined to\ndevelop approximations to the quantum density and thus find the approximate\nquantum force. The quantum force is then combined with a Lennard-Jones force to\nsimulate clusters of Argon atoms and to obtain the ground state configurations\nand energies.\n  As demonstration of the utility and flexibility of the approach, we compute\nthe lowest energy structures for small rare-glass clusters. Extensions to many\natom systems is straightforward."
    },
    {
        "anchor": "Glassy dynamics of a model of bacterial cytoplasm with metabolic\n  activities: Recent experiments have revealed that cytoplasms become glassy when their\nmetabolism is suppressed, while they maintain fluidity in a living state. The\nmechanism of this active fluidization is not clear, especially for bacterial\ncytoplasms, since they lack traditional motor proteins, which can cause\ndirected motions. We introduce a model of bacterial cytoplasm focusing on the\nimpact of conformational change in proteins due to metabolism. In the model,\nproteins are treated as particles under thermal agitation, and conformation\nchanges are treated as changes in particle volume. Simulations revealed that a\nsmall change in volume fluidizes the glassy state, accompanied by a change in\nfragility, as observed experimentally.",
        "positive": "Lateral phase separation of confined membranes: We consider membranes interacting via short, intermediate and long stickers.\nThe effects of the intermediate stickers on the lateral phase separation of the\nmembranes are studied via mean-field approximation. The critical potential\ndepth of the stickers increases in the presence of the intermediate sticker.\nThe lateral phase separation of the membrane thus suppressed by the\nintermediate stickers. Considering membranes interacting with short and long\nstickers, the effect of confinement on the phase behavior of the membranes is\nalso investigated analytically."
    },
    {
        "anchor": "Heated gas bubbles enrich, crystallize, dry, phosphorylate and\n  encapsulate prebiotic molecules: Non-equilibrium conditions must have been crucial for the assembly of the\nfirst informational polymers of early life, but supporting their formation and\ncontinuous enrichment in a long-lasting environment. Here, we explore how gas\nbubbles in water subjected to a thermal gradient, a likely scenario within\ncrustal mafic rocks on the early Earth, drive a complex, continuous enrichment\nof prebiotic molecules. NRA precursors, monomers, active ribozymes,\noligonucleotides and lipids are shown to (1) cycle between dry and wet states,\nenabling the central step of RNA phosphorylation, (2) accumulate at the\ngas-water interface to drastically increase ribozymatic activity, (3) condense\ninto hydrogels, (4) form pure crystals and (5) encapsulate into protecting\nvesicle aggregates that subsequently undergo fission. These effects occur\nwithin less than 30 min. The findings unite, in one location, the physical\nconditions that were crucial for the chemical emergence of biopolymers. They\nsuggest that heated microbubbles could have hosted the first cycles of\nmolecular evolution.",
        "positive": "Exciton Regeneration at Polymeric Semiconductor Heterojunctions: Control of the band-edge offsets at heterojunctions between organic\nsemiconductors allows efficient operation of either photovoltaic or\nlight-emitting diodes. We investigate systems where the exciton is marginally\nstable against charge separation, and show via E-field-dependent time-resolved\nphotoluminescence spectroscopy that excitons that have undergone charge\nseparation at a heterojunction can be efficiently regenerated. This is because\nthe charge transfer produces a geminate electron-hole pair (separation\n2.2-3.1nm) which may collapse into an exciplex and then endothermically\n(E=100-200meV) back-transfer towards the exciton."
    },
    {
        "anchor": "Pressure-driven flow of oligomeric fluid in nano-channel with complex\n  structure. A dissipative particle dynamics study: We develop a simulational methodology allowing for simulation of the\npressure-driven flow in the pore with flat and polymer-modified walls. Our\napproach is based on dissipative particle dynamics and we combine earlier ideas\nof fluid-like walls and reverse flow. As a test case we consider the oligomer\nflow through the pore with flat walls and demonstrate good thermostatting\nqualities of the proposed method. We found the inhomogeneities in both oligomer\nshape and alignment across the pore leading to a non-parabolic velocity\nprofiles. The method is subsequently applied to a nano-channel decorated with a\npolymer brush stripes arranged perpendicularly to the flow direction. At\ncertain threshold value of a flow force we find a pillar-to-lamellar\nmorphological transition, which leads to the brush enveloping the pore wall by\na relatively smooth layer. At higher flow rates, the flow of oligomer has\nsimilar properties as in the case of flat walls, but for the narrower effective\npore size. We observe stretching and aligning of the polymer molecules along\nthe flow near the pore walls.",
        "positive": "Jamming in Granular Polymers: We examine the jamming transition in a two-dimensional granular polymer\nsystem using compressional simulations. The jamming density \\phi_c decreases\nwith increasing length of the granular chain due to the formation of loop\nstructures, in excellent agreement with recent experiments. The jamming density\ncan be further reduced in mixtures of granular chains and granular rings, also\nas observed in experiment. We show that the nature of the jamming in granular\npolymer systems has pronounced differences from the jamming behavior observed\nfor polydisperse two-dimensional disk systems at Point J. This result provides\nfurther evidence that there is more than one type of jamming transition."
    },
    {
        "anchor": "Non-equilibrium first order transition marks the mechanical failure of\n  glasses: Glasses acquire their solid-like properties by cooling from the supercooled\nliquid via a continuous transition known as the glass transition. Recent\nresearch on soft glasses indicates that besides temperature, another route to\nliquify glasses is by application of stress that forces relaxation and flow.\nHere we provide experimental evidence that the stress-induced onset of flow of\nglasses occurs via a sharp first order-like transition. Using simultaneous\nx-ray scattering during the oscillatory rheology of a colloidal glass, we\nidentify a sharp symmetry change from anisotropic solid to isotropic liquid\nstructure at the transition from the linear to the nonlinear regime.\nConcomitantly, intensity fluctuations sharply acquire liquid distributions.\nThese observations identify the yielding of glasses to increasing stress as\nsharp affine-to-nonaffine transition, providing a new conceptual paradigm of\nthe yielding of this technologically important class of materials, and offering\nnew perspectives on the glass transition.",
        "positive": "Virtual surfaces, director domains and the Freedericksz transition in\n  polymer stabilized nematic liquid crystals: The critical field of the Freedericksz transition and switching dynamics are\ninvestigated for polymer stabilized nematic liquid crystals as a function of\npolymer concentration. A simple phenomenological model is proposed to describe\nthe observed critical field and dynamic response time behaviors as a function\nof concentration. In this model the polymer fibrils form director domains,\nwhich are bounded by virtual surfaces with a finite anchoring energy. The\nFreedericksz transition occurs independently within each of these domains."
    },
    {
        "anchor": "Electrowetting on dielectrics on lubricating fluid based slippery\n  surfaces with negligible hysteresis: Low voltage electrowetting on dielectrics on substrates with thin layer of\nlubricating fluid to reduce contact angle hysteresis is reported here. On\nsmooth and homogeneous solid surfaces, it is extremely difficult to reduce\ncontact angle hysteresis (contact angle difference between advancing and\nreceding drop volume cycle) and the electrowetting hysteresis (contact angle\ndifference between advancing and receding voltage cycle) below 10{\\deg}. On the\nother hand, electrowetting hysteresis on rough surfaces can be relatively large\n(>30{\\deg}) therefore they are of no use for most of the fluidic devices. In\nthe present report we demonstrate that using a thin layer of dielectric\nlubricating fluid on top of the solid dielectric surface results in drastic\nreduction in contact angle hysteresis as well as electrowetting hysteresis (<\n2{\\deg}) on smooth as well as rough surfaces. Subsequently fitting the\nLippmann-Young electrowetting equation to the experimental electrowetting data\nreveal that the dielectric lubricating fluid layer is only responsible for\nsmooth movement of the three phase contact line of the liquid drop and does not\naffect the effective specific capacitance of the system.",
        "positive": "The second and third Sonine coefficients of a freely cooling granular\n  gas revisited: In its simplest statistical-mechanical description, a granular fluid can be\nmodeled as composed of smooth inelastic hard spheres (with a constant\ncoefficient of normal restitution $\\alpha$) whose velocity distribution\nfunction obeys the Enskog-Boltzmann equation. The basic state of a granular\nfluid is the homogeneous cooling state, characterized by a homogeneous,\nisotropic, and stationary distribution of scaled velocities, $F(\\mathbf{c})$.\nThe behavior of $F(\\mathbf{c})$ in the domain of thermal velocities ($c\\sim 1$)\ncan be characterized by the two first non-trivial coefficients ($a_2$ and\n$a_3$) of an expansion in Sonine polynomials. The main goals of this paper are\nto review some of the previous efforts made to estimate (and measure in\ncomputer simulations) the $\\alpha$-dependence of $a_2$ and $a_3$, to report new\ncomputer simulations results of $a_2$ and $a_3$ for two-dimensional systems,\nand to investigate the possibility of proposing theoretical estimates of $a_2$\nand $a_3$ with an optimal compromise between simplicity and accuracy."
    },
    {
        "anchor": "Microscopic determination of correlations in the fluid interfacial\n  region in the presence of liquid-gas asymmetry: In a recent article, we showed how the properties of the density-density\ncorrelation function and its integral, the local structure factor, in the fluid\ninterfacial region, in systems with short-ranged forces, can be understood\nmicroscopically by considering the resonances of the local structure factor\n[Nat.Phys.~{\\bf 15}, 287 (2019)]. Here we illustrate, using mean-field\nsquare-gradient theory and the more microscopic Sullivan density functional\nmodel, how this approach generalises when there is liquid-gas asymmetry, i.e.\nwhen the bulk correlation lengths of the coexisting liquid and gas phases are\ndifferent. In particular, we are able to express the correlation function\n\\textit{exactly} as a simple average of contributions arising from two\neffective Ising-symmetric systems referred to as the symmetric gas and\nsymmetric liquid. When combined with our earlier results, this generates\nanalytical approximations for the correlation function and the local structure\nfactor, which are near indistinguishable from the numerical solution to the\nOrnstein-Zernike equations over the whole range of wave-vectors. Our results\nhighlight how asymmetry affects the correlation function structure, and\ndescribes the crossover from a long-ranged Goldstone mode to short-ranged\nproperties determined by the local density, as the wave-vector increases.",
        "positive": "Equilibration of a Polycation-Anionic Surfactant Mixture at the\n  Water-Vapor Interface: The adsorption of concentrated polydiallyldimethylammonium chloride,\nPDADMAC-sodium lauryl ether sulfate (SLES) mixtures at the water-vapor\ninterface has been studied by different surface tension techniques and\ndilational viscoelasticity measurements. This work tries to shed light on the\nway in which the formation of polyelectrolyte-surfactant complexes in the bulk\naffects the interfacial properties of mixtures formed by a polycation and an\noppositely charged surfactant. The results are discussed in terms of a two-step\nadsorption-equilibration of PDADMAC-SLES complexes at the interface, with the\ninitial stages involving the diffusion of kinetically trapped aggregates formed\nin the bulk to the interface followed by the dissociation and spreading of such\naggregates at the interface. This latter process becomes the main contribution\nto the surface tension decrease. This work aids our understanding of the most\nfundamental basis of the physicochemical behavior of concentrated\npolyelectrolyte-surfactant mixtures which present complex bulk and interfacial\ninteractions with interest in both basic and applied sciences."
    },
    {
        "anchor": "The Structure of Liquid Water Emerging from the Vibrational\n  Spectroscopy: Interpretation with QED Theory: We report an analysis of the stretching peak appearing in the IR experimental\nspectra of liquid water. In the literature, ATR-IR spectroscopic measurements\nwere repeatedly performed in a wide range of temperature and gave rise to a\nlively debate among scientists. In particular a two components model related to\nH-bond complexes of different strength have been proposed in order to justify\nthe existence of two types of molecules as it appears from the spectroscopic\ndata. At the opposite, Molecular Dynamics simulations support a multistate\n(continuum) system of H bond having different strength giving rise to a\n(locally) tetrahedral description of liquid water. We will show that liquid\nwater is a quantum two-level system according to the predictions of Quantum\nElectrodynamics (QED) and that several features (the asymmetric band profile,\nthe existence of an isosbestic point and the modifications of the vibrational\nstretching band with the temperature) cannot be fully justified in the realm of\na classical picture. In particular the differences of energy and entropy\nbetween the two phases are estimated from the experimental data and compared\nwith the prediction of QED showing a remarkable agreement. The behavior of\nwater near hydrophilic surfaces is also discussed and several feature of the so\ncalled Exclusion Zone observed by several authors are evaluated according to\nthe two level system model.",
        "positive": "Chiral self-sorting of active semiflexible filaments with intrinsic\n  curvature: Many-body interactions in systems of active matter can cause particles to\nmove collectively and self-organize into dynamic structures with long-range\norder. In cells, the self-assembly of cytoskeletal filaments is critical for\ncellular motility, structure, intracellular transport, and division.\nSemiflexible cytoskeletal filaments driven by polymerization or motor-protein\ninteractions on a two-dimensional substrate, such as the cell cortex, can\ninduce filament bending and curvature leading to interesting collective\nbehavior. For example, the bacterial cell-division filament FtsZ is known to\nhave intrinsic curvature that causes it to self-organize into rings and\nvortices, and recent experiments reconstituting the collective motion of\nmicrotubules driven by motor proteins on a surface have observed chiral\nsymmetry breaking of the collective behavior due to motor-induced curvature of\nthe filaments. Previous work on the self-organization of driven filament\nsystems have not studied the effects of curvature and filament structure on\ncollective behavior. In this work, we present Brownian dynamics simulation\nresults of driven semiflexible filaments with intrinsic curvature and\ninvestigate how the interplay between filament rigidity and radius of curvature\ncan tune the self-organization behavior in homochiral systems and heterochiral\nmixtures. We find a curvature-induced phase transition from polar flocks to\nself-sorted chiral clusters, which is modified by filament flexibility. This\nphase transition changes filament transport from ballistic to diffusive at long\ntimescales."
    },
    {
        "anchor": "Chaotic oscillation in attractive Bose-Einstein condensate under an\n  impulsive force: For an attractive trapped Bose-Einstein condensate an imaginary three-body\nrecombination loss term and an imaginary linear source term are usually\nincluded in the Gross-Pitaevskii (GP) equation for a proper account of\ndynamics. Under the action of an impulsive force, generated by suddenly\nchanging the atomic interaction or the trapping potential, the solution of this\ncomplex GP equation for attractive interaction is found to lead to a very long\nterm chaotic oscillation.",
        "positive": "Strong-coupling theory for a polarizable planar colloid: We propose a strong-coupling analysis of a polarizable planar interface, in\nthe spirit of a recently introduced Wigner-Crystal formulation. The system is\nmade up of two moieties: a semi-infinite medium (z<0) with permittivity\nepsilon' while the other half space in z>0 is occupied by a solution with\npermittivity epsilon, and mobile counter-ions (no added electrolyte). The\ninterface at z=0 bears a uniform surface charge. The counter-ion density\nprofile is worked out explicitly for both repulsive and attractive dielectric\nimage cases."
    },
    {
        "anchor": "Non-Hookean statistical mechanics of clamped graphene ribbons: Thermally fluctuating sheets and ribbons provide an intriguing forum in which\nto investigate strong violations of Hooke's Law: large distance elastic\nparameters are in fact not constant, but instead depend on the macroscopic\ndimensions. Inspired by recent experiments on free-standing graphene\ncantilevers, we combine the statistical mechanics of thin elastic plates and\nlarge-scale numerical simulations to investigate the thermal renormalization of\nthe bending rigidity of graphene ribbons clamped at one end. For ribbons of\ndimensions $W\\times L$ (with $L\\geq W$), the macroscopic bending rigidity\n$\\kappa_R$ determined from cantilever deformations is independent of the width\nwhen $W<\\ell_\\textrm{th}$, where $\\ell_\\textrm{th}$ is a thermal length scale,\nas expected. When $W>\\ell_\\textrm{th}$, however, this thermally renormalized\nbending rigidity begins to systematically increase, in agreement with the\nscaling theory, although in our simulations we were not quite able to reach the\nsystem sizes necessary to determine the fully developed power law dependence on\n$W$. When the ribbon length $L > \\ell_p$, where $\\ell_p$ is the $W$-dependent\nthermally renormalized ribbon persistence length, we observe a scaling collapse\nand the beginnings of large scale random walk behavior.",
        "positive": "Instability patterns in ultrathin nematic films: comparison between\n  theory and experiment: Motivated by recent experimental observations [U. Delabre et al, Langmuir 24,\n3998, 2008] we reconsider an instability of ultrathin nematic films, spread on\nliquid substrates. Within a continuum elastic theory of liquid crystals, in the\nharmonic approximation, we find an analytical expressions for the critical\nthickness as well as for the critical wavenumber, characterizing the onset of\ninstability towards the stripe phase. Comparing theoretical predictions with\nexperimental observations, we establish the utility of surface-like term such\nas an azimuthal anchoring."
    },
    {
        "anchor": "Importance of transverse dipoles in the stability of biaxial nematic\n  phase: A Monte Carlo study: Monte Carlo simulation performed on a lattice system of biaxial molecules\npossessing $D_{2h}$ symmetry and interacting with a second rank anisotropic\ndispersion potential yields three distinct macroscopic phases depending on the\nbiaxiality of the constituent molecules. The phase diagram of such a system as\na function of molecular biaxiality is greatly modified when a transverse dipole\nis considered to be associated with each molecule so that the symmetry is\nreduced to $C_{2v}$. Our results indicate the splitting of the Landau point\ni.e. the point in the phase diagram where a direct transition from the\nisotropic phase to the biaxial nematic phase occurs, into a Landau line for a\nsystem of biaxial molecules with strong transverse dipoles. The width of the\nLandau line becomes maximum for an optimal value of the relative dipolar\nstrength. The presence of transverse dipoles leads to the stabilization of the\nthermotropic biaxial nematic phase at higher temperature and for a range of\nvalues of molecular biaxiality. The structural properties in the uniaxial and\nbiaxial phases are investigated by evaluating the first rank and second rank\norientational correlation functions. The dipole induced long range order of the\nanti-ferroelectric structure in the biaxial nematic phase, is revealed.",
        "positive": "Rheology of Attractive Emulsions: We show how attractive interactions dramatically influence emulsion rheology.\nUnlike the repulsive case, attractive emulsions below random close packing,\nRCP, can form soft gel-like elastic solids. However, above RCP, attractive and\nrepulsive emulsions have similar elasticities. Such compressed attractive\nemulsions undergo an additional shear-driven relaxation process during\nyielding. Our results suggest that attractive emulsions begin to yield at weak\npoints through the breakage of bonds, and, above RCP, also undergo droplet\nconfigurational rearrangements."
    },
    {
        "anchor": "Modeling induction period of polymer crystallization: We study the possibility of the spinodal decomposition in the induction\nperiod of the polymer crystallization. This phenomenon was first reported in an\nX-ray scattering experiment, and has still been controversial due to various\nexperiments and theories that support or deny the phenomenon. In this article,\nwe explain the condition for the spinodal decomposition to occur in polymer\nmelts by deriving a Ginzburg-Landau model of the free energy as a functional of\nthe density and the orientation of the segments, where we introduce the\nexcluded volume and the nematic interactions through a combination of the\nrandom phase approximation and the transfer matrix for the polymer\nconformation. We show that, upon elimination of the degrees of freedom of the\norientation, the nematic interaction reduces to an effective attraction whose\nstrength increases with the stiffness of the polymer chain. Such an attraction\ninduces spinodal decomposion especially for stiff polymer chain case.",
        "positive": "Microphase separation as the cause of structural complexity in 2D\n  liquids: Complex behavior in glassforming liquids is associated with formation of a\nmosaic of different structures. Using bond order parameters together with\ntopological characteristics of the bond network, we show that in the mosaic of\ncrystalline and amorphous clusters found in a 2D liquid the difference between\nstructural sub- components translates into a difference between two coexisting\nphases. We suggest that the observed microphase separated mosaic is a 2D\nrealization of what is usually invoked to explain special features found in 3D\ncomplex liquids. Conditions favoring mosaic stability are discussed; these\nconditions include a new type of critical behavior and long-range correlations\nbetween sub-component clusters."
    },
    {
        "anchor": "Inhomogeneous DNA: conducting exons and insulating introns: Parts of DNA sequences known as exons and introns play very different role in\ncoding and storage of genetic information. Here we show that their conducting\nproperties are also very different. Taking into account long-range correlations\namong four basic nucleotides that form double-stranded DNA sequence, we\ncalculate electron localization length for exon and intron regions. Analyzing\ndifferent DNA molecules, we obtain that the exons have narrow bands of extended\nstates, unlike the introns where all the states are well localized. The band of\nextended states is due to a specific form of the binary correlation function of\nthe sequence of basic DNA nucleotides.",
        "positive": "Behavior of colloidal particles at an air/nematic liquid crystal\n  interface: We examine the behavior of spherical silica particles trapped at an\nair-nematic liquid crystal interface. When a strong normal anchoring is\nimposed, the beads spontaneously form various structures depending on their\narea density and the nematic thickness. Using optical tweezers, we determine\nthe pair potential and explain the formation of these patterns. The energy\nprofile is discussed in terms of capillary and elastic interactions. Finally,\nwe detail the mechanisms that control the formation of an hexagonal lattice and\nanalyze the role of gravity for curved interfaces."
    },
    {
        "anchor": "Friction of the micron-scale silica under various behaviors of the shape\n  and the orientation of the coarse-grained particle in adaptive smoothed\n  particle hydrodynamics: The paper investigates dry sliding friction of the coarse-grained micronscale\n{\\alpha}-SiO2 oxide. Adaptive smoothed particle approach is used to consider\nvarious shapes and orientations of the particles. It is found that because of\nthe stable system the friction characteristics almost do not depend on the\nshape and the orientation of the particle. The friction coefficient of 0.1376\nobserved in the present work is in accordance with that found in previously\nexperimental reports. The friction coefficient steady maintains in the applied\nload range of 5-80 {\\mu}N, showing a very slightly linear drop from 0.1379 to\n0.1341 in this load range. This observation is also consistent with the applied\nload-friction coefficient relationship mentioned in previously experimental\nstudies.",
        "positive": "Microfluidic probing of the complex interfacial rheology of multilayer\n  capsules: Encapsulation of chemicals using polymer membranes enables to control their\ntransport and delivery for applications such as agrochemistry or detergency. To\nrationalize the design of polymer capsules, it is necessary to understand how\nthe membranes' mechanical properties control the transport and release of the\ncargo. In this article, we use microfluidics to produce model polymer capsules\nand study in situ their behavior in controlled elongational flows. Our model\ncapsules are obtained by assembling polymer mono and hydrogen-bonded bilayers\nat the surface of an oil droplet in water. We also use microfluidics to probe\nin situ the mechanical properties of the membranes in a controlled elongational\nflow generated by introducing the capsules through a constriction and then in a\nlarger chamber. The deformation and relaxation of the capsules depend on their\ncomposition and especially on the molecular interactions between the polymer\nchains that form the membranes and the anchoring energy of the first layer. We\ndevelop a model and perform numerical simulations to extract the main\ninterfacial properties of the capsules from the measurement of their\ndeformations in the microchannels."
    },
    {
        "anchor": "Parametrization of the Charge-Carrier Mobility in Organic Disordered\n  Semiconductors. APAE against EGDM: An appropriately parameterized compact analytical equation (APAE) is\nsuggested to account for charge carrier mobility in organic disordered\nsemiconductors (ODSs). This equation correctly reproduces the effects of\ntemperature $T$, carrier concentration $n$, and electric field $F$ on the\ncarrier mobility $\\mu(T,F,n)$, as evidenced by comparison with analytical\ntheories and Monte Carlo simulations. The set of material parameters\nresponsible for charge transport is proven to be at varience to those used in\nthe so-called extended Gaussian disorder model (EGDM) approach, which is widely\nexploited in commercially distributed device--simulation algorithms. While EGDM\nis only valid for cubic lattices with a specific choice of parameters, APAE\ndescribes charge transport in systems with spatial disorder in a wide range of\nparameters. APAE is user-friendly and, thus, suitable for incorporation into\ndevice-simulation algorithms.",
        "positive": "Sudden chain energy transfer events in vibrated granular media: In a mixture of two species of grains of equal size but different mass,\nplaced in a vertically vibrated shallow box, there is spontaneous segregation.\nOnce the system is at least partly segregated and clusters of the heavy\nparticles have formed, there are sudden peaks of the horizontal kinetic energy\nof the heavy particles, that is otherwise small. Together with the energy peaks\nthe clusters rapidly expand and the segregation is partially lost. The process\nrepeats once segregation has taken place again. Depending on the experimental\nor numerical parameters, the energy bursts can occur either randomly or with\nsome regularity in time. An explanation for these events is provided based on\nthe existence of a fixed point for an isolated particle bouncing with only\nvertical motion. The horizontal energy peaks occur when the energy stored in\nthe vertical motion is partly transferred into horizontal energy through a\nchain reaction of collisions between heavy particles. A necessary condition for\nthe observed regularity of the events is that chain reactions involve most of\nthe heavy particles."
    },
    {
        "anchor": "Freezing and collapse of flexible polymers: We analyze the freezing and collapse transition of a simple model for\nflexible polymer chains on simple cubic and face-centered cubic lattices by\nmeans of sophisticated chain-growth methods. In contrast to bond-fluctuation\npolymer models in certain parameter ranges, where these two conformational\ntransitions were found to merge in the thermodynamic limit, we conclude from\nour results that the two transitions remain well-separated in the limit of\ninfinite chain lengths. The reason for this qualitatively distinct behavior is\npresumably due to the ultrashort attractive interaction range in the lattice\nmodels considered here.",
        "positive": "Translational Dynamics of Rod-like Particles in Supercooled Liquids:\n  Probing Dynamic Heterogeneity and Amorphous Order: The use of probe molecules to extract the local dynamical and structural\nproperties of complex dynamical systems is an age-old technique both in\nsimulations and experiments. A lot of important information which is not\nimmediately accessible from the bulk measurements can be accessed via these\nlocal measurements. Still, a detailed understanding of how a probe particle's\ndynamics are affected by the surrounding liquid medium is not very well\nunderstood, especially in the supercooled temperature regime. This work shows\nhow translational dynamics of a rod-like particle immersed in a supercooled\nliquid can give us information on the growth of the correlation length scale\nassociated with dynamical heterogeneity and the multi-body static correlations\nin the medium. A unified scaling theory rationalizes all the observed results\nleading to the development of a novel yet simple method that is accessible in\nexperiments to measure the growth of these important length-scales in molecular\nglass-forming liquids."
    },
    {
        "anchor": "Experimental and computer simulation studies of the micelles formed by\n  comb-like PEG-containing polymeric surfactants as potential enzyme scaffolds: The industrial implementation of biofuel production from lignocellulosic\nbiomass faces a number of economic obstacles. One of these is the cost of\nenzymes, typically used for cellulose hydrolysis. Nature provides some hints\ntowards the efficiency of this process, exampled in natural enzyme complexes -\ncellulosomes, produced by some microorganisms. Therefore, many research groups\ntarget synthetic routes to mimic such cellulosomes with synthetic structures\nwhen many questions remain to be addressed: the optimal chemical structure and\nsize of such synthetic scaffolds, their adsorption on the cellulosic biomass\nparticles, combinations, and best practices arrangement of enzymes in the\ncomplex. In this work, polyethylene glycol (PEG) copolymers that form micelles\nand accommodate enzymes in the micellar structures are systematically studied\nusing both experimental and computer simulation techniques. Preliminary results\nindicate that the micelles are efficient polymer - enzymes structures for\ncellulose hydrolysis. While the direct quantitative comparison between the real\nand model systems is not always straightforward, both approaches agree on the\nrole of the molecular architecture of the copolymers on micelle formation and\ntheir structural characteristics.",
        "positive": "Dewetting, partial wetting and spreading of a two-dimensional monolayer\n  on solid surface: We study the behavior of a semi-infinite monolayer, which is placed initially\non a half of an infinite in both directions, ideal crystalline surface, and\nthen evolves in time due to random motion of the monolayer particles. Particles\ndynamics is modeled as the Kawasaki particle-vacancy exchange process in the\npresence of long-range attractive particle-particle interactions. In terms of\nan analytically solvable mean-field-type approximation we calculate the mean\ndisplacement X(t) of the monolayer edge and discuss the conditions under which\nsuch a monolayer spreads (X(t) > 0), partially wets (X(t) = 0) or dewets from\nthe solid surface (X(t) < 0)."
    },
    {
        "anchor": "Pattern transition of flow dynamics in a highly water-absorbent granular\n  bed: An aqueous sodium chloride solution was injected at a controlled rate into a\ngranular bed in a quasi-two-dimensional cell. The granular bed was made of\ndried, highly water-absorbent gel particles whose swelling rate was controlled\nby the salinity of the injected fluid. At a high salinity level (low swelling\nrate), high injection rate, and short timescale, the injected fluid percolated\nbetween the gel particles in an isotropic manner. Meanwhile, at a low salinity\nlevel (high swelling rate), low injection rate, and long timescale, the gel\nparticles clogged the flow path, resulting in anisotropic branch-like\nstructures of the injected fluid front. The transition of the injection pattern\ncould be understood based on the ratio of the characteristic timescales of\nswelling and injection. Moreover, the clogged pattern showed an oscillatory\npressure drop whose amplitude was increased with higher salinity. Such an\noscillatory behavior observed in an injection process in a swelling gel\nparticle may be relevant in geological situation; i.e., such as fluid migration\nunderground.",
        "positive": "The planar interface instability during freezing of a polymer solution:\n  Diffusion-controlled or not?: Freezing of polymer solutions has been extensively investigated from many\naspects, especially the complex pattern formation. The cell/dendrite\nmicro-structures are believed to be in the type of diffusion-induced M-S\ninstability. However, the presence of polymer as an impurity in water is\nsignificantly different from that of small ions. The quantitative transient\ninvestigation on directional freezing of polymer solutions remains lack due to\nsome challenges. For the first time, we observed the planar instability\nbehaviors during unidirectional freezing of a polymer solution together with a\ntypical ionic solution with manipulated ice orientation, and their pattern\nformation of S/L interface morphology as a function of time in the transient\nplanar instability process has been revealed and compared to each other. It is\nfound with real-time observation that the polymer solution exhibits a global\ninstability mode instead of a local instability mode that is common in ionic\nsolution during planar instability. W-L model was applied to quantitatively\naddress the variation of solute recoil of ionic/polymer solution. And it is\nfound that the W-L model can only reproduce the solute recoil of ionic solution\ninstead of polymer solution, which indicates the complex physics behind\nfreezing of a polymer solution. The paper provides a spectacular contrast of\ndirectional freezing process between polymer solution and ionic solution and is\nbelieved to promote relevant investigations in terms of the theoretical\napproach to describing the freezing behavior of polymer solution."
    },
    {
        "anchor": "Vegetable oil hybrid films cross-linked at the air-water interface:\n  formation kinetics and physical characterization: Vegetable oil based hybrid films were developed thanks to a novel solvent-\nand heating- free method at the air-water interface using silylated castor oil\ncross-linked via a sol-gel reaction. To understand the mechanism of the hybrid\nfilm formation, the reaction kinetics was studied in detail by using\ncomplementary techniques: rheology, thermogravimetric analysis, and infrared\nspectroscopy. The mechanical properties of the final films were investigated by\nnano-indentation, whereas their structure was studied using a combination of\nwide-angle X-ray scattering, electron diffraction, and atomic force microscopy.\nWe found that solid and transparent films form in 24 hours and, by changing the\nsilica precursor to castor oil ratio, their mechanical properties are tunable\nin the MPa-range by about a factor of twenty. In addition to that, a possible\noptimization of the cross-linking reaction with different catalysts was\nexplored and finally, cytotoxicity tests were performed on fibroblasts proving\nthe absence of film toxicity. The results of this work pave the way to a\nstraightforward synthesis of castor-oil films with tunable mechanical\nproperties: hybrid films cross-linked at the air-water interface combine an\neasy and cheap spreading protocol with the features of their thermal history\noptimized for possible future micro/nano drug loading, thus representing\nexcellent candidates for the replacement of non-environment friendly\npetroleum-based materials.",
        "positive": "Nonlinear ER effects in an ac applied field: The electric field used in most electrorheological (ER) experiments is\nusually quite high, and nonlinear ER effects have been theoretically predicted\nand experimentally measured recently. A direct method of measuring the\nnonlinear ER effects is to examine the frequency dependence of the same\neffects. For a sinusoidal applied field, we calculate the ac response which\ngenerally includes higher harmonics. In is work, we develop a multiple image\nformula, and calculate the total dipole moments of a pair of dielectric\nspheres, embedded in a nonlinear host. The higher harmonics due to the\nnonlinearity are calculated systematically."
    },
    {
        "anchor": "A Novel Method for Studying the Dynamics of Confined Polymers in\n  Nanoparticles in Nanoblends: The advances in new technologies have prompted the need for functional\nsystems smaller than the gyration radius of polymer chains. Thus, understanding\nhow nanoconfinement affects polymer properties has been the focus of a lot of\nresearch for over a decade. Polystyrene in particular has been reported to be\nstrongly affected when nanoconfined as a thin film and specifically its glass\ntransition temperature (Tg) is reported to decrease with decreasing film\nthickness. Tremendous effort has been dedicated to developing methods for\nquantifying the large-scale dynamic of nanoconfined polymers: film dewetting,\nfilm contraction, nanobubble inflation, nanoparticle imbedding and healing of\ndeformed surfaces etc. In this work we describe a novel method to study the\nlarge scale dynamic and nanomechanical properties of nanoconfined polymers in\nnanoparticles in nanoblends. Nanoblends of dPS/PBMA were prepared from a\nmixture of colloidal suspensions of cross-linked PBMA and traces of dPS\nnanoparticles via water evaporation. The polymer blends were prepared at\ntemperatures well below the glass transition of PS (TgPS) and above the Tg of\ncross-linked PBMA particles (TgPBMA). In these conditions we expect the PBMA\nparticles to deform under capillary pressure to fill the interstices between\nthem and the glassy PS nanoparticles to remain spherical. During the\npreparation of the nanoblends the elastic energy is stored within the deformed\ncross-linked PBMA nanoparticles. Upon annealing the films above TgPS, the PBMA\nnanoparticles regain their spherical shape and release the stored elastic\nenergy, which induces the deformation of the PS nanoparticles. Small angle\nneutron scattering is then used to monitor the shape evolution of the PS\nnanoparticles and to quantify the relaxation dynamics of the polystyrene\nnanoparticles.",
        "positive": "Analysis of Two-State Folding Using Parabolic Approximation II:\n  Temperature-Dependence: Equations that govern the temperature-dependence of the rate constants, Gibbs\nenergies,enthalpies, entropies and heat capacities of activation for folding\nand unfolding of spontaneously-folding fixed two-state systems have been\nderived using a procedure that treats the denatured and the native conformers\nas being confined to harmonic Gibbs energy wells. The notion that a two-state\nsystem is physically defined only for a set temperature range is introduced.\nThe implications of this novel treatment for protein folding are discussed."
    },
    {
        "anchor": "Virial coefficients and demixing of athermal nonadditive mixtures: We compute the fourth virial coefficient of a binary nonadditive hard-sphere\nmixture over a wide range of deviations from diameter additivity and size\nratios. Hinging on this knowledge, we build up a $y$ expansion [B. Barboy and\nW. N. Gelbart, J. Chem. Phys. {\\bf 71}, 3053 (1979)] in order to trace the\nfluid-fluid coexistence lines which we then compare with the available\nGibbs-ensemble Monte Carlo data and with the estimates obtained through two\nrefined integral-equation theories of the fluid state. We find that in a regime\nof moderately negative nonadditivity and largely asymmetric diameters, relevant\nto the modelling of sterically and electrostatically stabilized colloidal\nmixtures, the fluid-fluid critical point is unstable with respect to\ncrystallization.",
        "positive": "Resonances arising from hydrodynamic memory in Brownian motion - The\n  colour of thermal noise: Observation of the Brownian motion of a small probe interacting with its\nenvironment is one of the main strategies to characterize soft matter.\nEssentially two counteracting forces govern the motion of the Brownian\nparticle. First, the particle is driven by the rapid collisions with the\nsurrounding solvent molecules, referred to as thermal noise. Second, the\nfriction between the particle and the viscous solvent damps its motion.\nConventionally, the thermal force is assumed to be random and characterized by\na white noise spectrum. Friction is assumed to be given by the Stokes drag,\nimplying that motion is overdamped. However, as the particle receives momentum\nfrom the fluctuating fluid molecules, it also displaces the fluid in its\nimmediate vicinity. The entrained fluid acts back on the sphere and gives rise\nto long-range correlation. This hydrodynamic memory translates to thermal\nforces, which display a coloured noise spectrum. Even 100 years after Perrin's\npioneering experiments on Brownian motion, direct experimental observation of\nthis colour has remained elusive. Here, we measure the spectrum of thermal\nnoise by confining the Brownian fluctuations of a microsphere by a strong\noptical trap. We show that due to hydrodynamic correlations the power spectral\ndensity of the spheres positional fluctuations exhibits a resonant peak in\nstrong contrast to overdamped systems. Furthermore, we demonstrate that peak\namplification can be achieved through parametric excitation. In analogy to\nMicrocantilever-based sensors our results demonstrate that the\nparticle-fluid-trap system can be considered as a nanomechanical resonator,\nwhere the intrinsic hydrodynamic backflow enhances resonance. Therefore,\ninstead of being a disturbance, details in thermal noise can be exploited for\nthe development of new types of sensors and particle-based assays for\nlab-on-a-chip applications."
    },
    {
        "anchor": "Selective solute adsorption and partitioning around single PNIPAM chains: Thermoresponsive polymer architectures have become integral building blocks\nof 'smart' functional materials in modern applications. For a large range of\ndevelopments, e.g., for drug delivery or nanocatalytic carrier systems, the\nselective adsorption and partitioning of molecules (ligands or reactants)\ninside the polymeric matrix are key processes that have to be controlled and\ntuned for the desired material function. In order to gain insights into the\nnanoscale structure and binding details in such systems, we here employ\nmolecular dynamics simulations of the popular poly(N-isopropylacrylamide)\n(PNIPAM) polymer in explicit water in the presence of various representative\nsolute types with focus on aromatic model reactants. We model a PNIPAM polymer\nchain and explore the influence of its elongation, stereochemistry, and\ntemperature on the solute binding affinities. While we find that the excess\nadsorption generally raises with the size of the solute, the temperature-\ndependent affinity to the chains is highly solute specific and has a\nconsiderable dependence on the polymer elongation (i.e., polymer swelling\nstate). We elucidate the molecular mechanisms of the selective binding in\ndetail and eventually present how the results can be extrapolated to\nmacroscopic partitioning of the solutes in swollen polymer architectures, such\nas hydrogels.",
        "positive": "Detecting and characterizing phase transitions in active matter using\n  entropy: A major challenge in the study of active matter lies in quantitative\ncharacterization of phases and transitions between them. We show how the\nentropy of a collection of active objects can be used to classify regimes and\nspatial patterns in their collective behavior. Specifically, we estimate the\ncontributions to the total entropy from correlations between the degrees of\nfreedom of position and orientation. This analysis pin-points the flocking\ntransition in the Vicsek model while clarifying the physical mechanism behind\nthe transition. When applied to experiments on swarming Bacillus subtilis with\ndifferent cell aspect ratios and overall bacterial area fractions, the entropy\nanalysis reveals a rich phase diagram with transitions between qualitatively\ndifferent swarm statistics. We discuss physical and biological implications of\nthese findings."
    },
    {
        "anchor": "Effects of orientational order on modulated cylindrical interfaces: Cylindrical interfaces occur in sheared or deformed emulsions and as\nbiological or technological lipid monolayer or bilayer tubules. Like the\ncorresponding spherical droplets and vesicles, these cylinder-like surfaces may\nhost orientaional order with $n$-fold rotational symmetry, for example in the\npositions of lipid molecules or of spherical nanoparticles. We examine how that\norder interacts with and induces shape modulations of cylindrical interfaces.\nWhile on spherical droplets $2n$ topological defects necessarily exist and can\ninduce icosahedral droplet shapes, the cylindrical topology is compatible with\na defect-free patterning. Nevertheless, once a modulation is introduced by a\nmechanism such as spontaneous curvature, nontrivial patterns of order,\nincluding ones with excess defects, emerge and have nonlinear effects on the\nshape of the tube. Examining the equilibrium energetics of the system\nanalytically and with a lattice-based Markov chain Monte Carlo simulation, we\npredict low-temperature morphologies of modulated cylindrical interfaces\nhosting orientational order. A shape modulation induces a banded pattern of\nalternatingly isotropic and ordered interfacial material. Furthermore\ncylindrical systems can be divided into Type I, without defects, and Type II,\nwhich go through a spectrum of defect states with up to $4n$ excess defects.\nThe character of the curvature-induced shape transition from unmodulated to\nmodulated cylinders is continuous or discontinuous accordingly.",
        "positive": "Finite size effects in critical fiber networks: Fibrous networks such as collagen are common in physiological systems. One\nimportant function of these networks is to provide mechanical stability for\ncells and tissues. At physiological levels of connectivity, such networks would\nbe mechanically unstable with only central-force interactions. While networks\ncan be stabilized by bending interactions, it has also been shown that they\nexhibit a critical transition from floppy to rigid as a function of applied\nstrain. Beyond a certain strain threshold, it is predicted that\nunderconstrained networks with only central-force interactions exhibit a\ndiscontinuity in the shear modulus. We study the finite-size scaling behavior\nof this transition and identify both the mechanical discontinuity and critical\nexponents in the thermodynamic limit. We find both non-mean-field behavior and\nevidence for a hyperscaling relation for the critical exponents, for which the\nnetwork stiffness is analogous to the heat capacity for thermal phase\ntransitions. Further evidence for this is also found in the self-averaging\nproperties of fiber networks."
    },
    {
        "anchor": "Monte Carlo simulations of a coarse grained model for an athermal\n  all-polystyrene nanocomposite system: The structure of a polystyrene matrix filled with tightly cross-linked\npolystyrene nanoparticles, forming an athermal nanocomposite system, is\ninvestigated by means of a Monte Carlo sampling formalism. The polymer chains\nare represented as random walks and the system is described through a coarse\ngrained Hamiltonian. This approach is related to self-consistent-field theory\nbut does not invoke a saddle point approximation and is suitable for treating\nlarge three-dimensional systems. The local structure of the polymer matrix in\nthe vicinity of the nanoparticles is found to be different in many ways from\nthat of the corresponding bulk, both at the segment and the chain level. The\nlocal polymer density profile near to the particle displays a maximum and the\nbonds develop considerable orientation parallel to the nanoparticle surface.\nThe depletion layer thickness is also analyzed. The chains orient with their\nlongest dimension parallel to the surface of the particles. Their intrinsic\nshape, as characterized by spans and principal moments of inertia, is found to\nbe a strong function of position relative to the interface. The dispersion of\nmany nanoparticles in the polymeric matrix leads to extension of the chains\nwhen their size is similar to the radius of the dispersed particles.",
        "positive": "Mesoscopic simulations of polyelectrolyte electrophoresis in\n  nanochannels: We present the results of mesoscopic dissipative particle dynamics (DPD)\nsimulations of coupled electrohydrodynamic phenomena on the micro- and\nnanoscale. The effects of electroosmotic flow and slippage combined with\npolyelectrolyte electrophoresis are investigated in detail, taking full account\nof hydrodynamic and electrostatic interactions. Our numerical results are in\nexcellent agreement with analytical calculations."
    },
    {
        "anchor": "Soft channel formation and symmetry breaking in exotic active emulsions: We use computer simulations to study the morphology and rheological\nproperties of a bidimensional emulsion resulting from a mixture of a passive\nisotropic fluid and an active contractile polar gel, in the presence of a\nsurfactant that favours the emulsification of the two phases. By varying the\nintensity of the contractile activity and of an externally imposed shear flow,\nwe find three possible morphologies. For low shear rates, a simple lamellar\nstate is obtained. For intermediate activity and shear rate, an asymmetric\nstate emerges, which is characterized by shear and concentration banding at the\npolar/isotropic interface. A further increment in the active forcing leads to\nthe self-assembly of a soft channel where an isotropic fluid flows between two\nlayers of active material. We characterize the stability of this state by\nperforming a dynamical test varying the intensity of the active forcing and\nshear rate. Finally, we address the rheological properties of the system by\nmeasuring the effective shear viscosity, finding that this increases as active\nforcing is increased, so that the fluid thickens with activity.",
        "positive": "Characteristic time and length scales in melts of Kremer-Grest\n  bead-spring polymers with wormlike bending stiffness: The Kremer-Grest (KG) model is a standard for studying generic polymer\nproperties. Here we have equilibrated KG melts up to and beyond $200$\nentanglements per chain for varying chain stiffness. We present methods for\nestimating the Kuhn length corrected for incompressibility effects, for\nestimating the entanglement length corrected for chain stiffness, for\nestimating bead frictions and Kuhn times taking into account entanglement\neffects. These are the key parameters for enabling quantitative, accurate, and\nparameter free comparisons between theory, experiment and simulations of KG\npolymer models with varying stiffness. We demonstrate this for the mean-square\nmonomer displacements in moderately to highly entangled melts as well as for\nthe shear relaxation modulus for unentangled melts, which are found to be in\nexcellent agreement with the predictions from standard theories of polymer\ndynamics."
    },
    {
        "anchor": "Phase behaviour of hard cylinders: Using isobaric Monte Carlo simulations, we map out the entire phase diagram\nof a system of hard cylindrical particles of length $L$ and diameter $D$, using\nan improved algorithm to identify the overlap condition between two cylinders.\nBoth the prolate $L/D>1$ and the oblate $L/D<1$ phase diagrams are reported\nwith no solution of continuity. In the prolate $L/D>1$ case, we find\nintermediate nematic \\textrm{N} and smectic \\textrm{SmA} phases in addition to\na low density isotropic \\textrm{I} and a high density crystal \\textrm{X} phase,\nwith \\textrm{I-N-SmA} and \\textrm{I-SmA-X} triple points. An apparent columnar\nphase \\textrm{C} is shown to be metastable as in the case of spherocylinders.\nIn the oblate $L/D<1$ case, we find stable intermediate cubatic \\textrm{Cub},\nnematic \\textrm{N}, and columnar \\textrm{C} phases with \\textrm{I-N-Cub},\n\\textrm{N-Cub-C}, and \\textrm{I-Cub-C} triple points. Comparison with previous\nnumerical and analytical studies is discussed. The present study, accounting\nfor the explicit cylindrical shape, paves the way to more sophisticated models\nwith important biological applications, such as viruses and nucleosomes.",
        "positive": "Signatures of motor susceptibility in the dynamics of a tracer particle\n  in an active gel: We study a model for the motion of a tracer particle inside an active gel,\nexposing the properties of the van Hove distribution of the particle\ndisplacements. Active events of a typical force magnitude give rise to\nnon-Gaussian distributions, having exponential tails or side-peaks. The\nside-peaks appear when the local bulk elasticity of the gel is large enough and\nfew active sources are dominant. We explain the regimes of the different\ndistributions, and study the structure of the peaks for active sources that are\nsusceptible to the elastic stress that they cause inside the gel. We show how\nthe van Hove distribution is altered by both the duty cycle of the active\nsources and their susceptibility, and suggest it as a sensitive probe to\nanalyze microrheology data in active systems with restoring elastic forces."
    },
    {
        "anchor": "Optimizing the Accuracy of Viscoelastic Characterization with AFM\n  Force-Distance Experiments in the Time and Frequency Domains: We demonstrate that the method of characterizing viscoelastic materials with\nAtomic Force Microscopy (AFM) by fitting analytical models to force-distance\n(FD) curves often yields conflicting and physically unrealistic results.\nBecause this method involves specifying a constitutive time-dependent\nviscoelastic model and then fitting said model to the experimental data, we\nshow that the inconsistencies in this method are due to a lack of sensitivity\nof the model with respect to its parameters. Using approaches from information\ntheory, this lack of sensitivity can be interpreted as a narrowed distribution\nof information which is obtained from the experiment. Furthermore, the\nequivalent representation of the problem in the frequency domain, achieved via\nmodified Fourier transformation, offers an enhanced sensitivity through a\nwidening of the information distribution. Using these distributions, we then\ndefine restrictions for the timescales which can be reliably accessed in both\nthe time and frequency domains, which leads to the conclusion that the analysis\nof experiments in the time domain can frequently lead to inaccuracies. Finally,\nwe provide an example where we use these restrictions as a guide to optimally\ndesign an experiment to characterize a polydimethylsiloxane (PDMS) polymer\nsample.",
        "positive": "From plastic flow to brittle fracture: role of microscopic friction in\n  amorphous solids: Plasticity in soft amorphous materials typically involves collective\ndeformation patterns that emerge upon intense shearing. The microscopic basis\nof amorphous plasticity has been commonly established through the notion of\n\"Eshelby\"-type events, localized abrupt rearrangements that induce flow in the\nsurrounding material via non-local elastic-type interactions. This universal\nmechanism in flowing disordered solids has been proposed despite their\ndiversity in terms of scales, microscopic constituents, or interactions.\nHowever, we argue that the presence of frictional interactions in granular\nsolids alters the dynamics of flow by nucleating micro shear cracks that\ncontinually coalesce to build up system-spanning fracture-like formations on\napproach to failure. The plastic-to-brittle failure transition is uniquely\ncontrolled by the degree of frictional resistance which is in essence similar\nto the role of heterogeneities that separate the abrupt and smooth yielding\nregimes in glassy structures."
    },
    {
        "anchor": "The Nonequilibrium Crystallization Force: The forces exerted by growing crystals on the surrounding materials play a\nmajor role in many geological processes, from diagenetic replacement to rock\nweathering and uplifting of rocks and soils. Although crystallization is a\nnonequilibrium process, the available theoretical prediction for these forces\nare based on equilibrium thermodynamics. Here we show that nonequilibrium\neffects can lead to a drop of the crystallization force in large pores where\nthe crystal surface dissociates from the surrounding walls during growth. The\ncritical pore size above which such detachment can be observed depends only on\nthe ratio of kinetic coefficients and cannot be predicted from thermodynamics.\nOur conclusions are based on a physical model which accounts for the\nnonequilibrium kinetics of mass transport, and disjoining pressure effects\nwithin the thin liquid film separating the crystal and the surrounding walls.\nOur results suggest that the maximum size of the pores that can sustain\ncrystallization forces close to the equilibrium prediction ranges from\nmicrometers for salts to a millimetre for low solubility minerals such as\ncalcite. These results are discussed in the light of recent experimental\nobservations of the growth of confined salt crystals.",
        "positive": "Design of Liquid Impregnated Surface with Stable Lubricant layer in\n  Mixed Water/Oil Environment for Low Hydrate Adhesion: Clathrate hydrate is a naturally occurring ice-like solid which forms in\nwater phase under suitable temperature and pressure conditions, in the presence\nof one or more hydrophobic molecules. It also forms inside the oil and gas\npipes leading to higher pumping cost, flow blockage and even catastrophic\naccidents. Engineered surfaces with low hydrate adhesion can provide an\neffective solution to this problem. Liquid impregnated surfaces is one such\nexample of engineered surfaces which has already shown tremendous potential in\nreducing the nucleation and adhesion of solids. Here we report the design and\nsynthesis of liquid impregnated surfaces with extremely low hydrate adhesion\nunder the mixed environment of oil and water. The most challenging aspect of\ndesigning these surfaces was to stabilize a lubricant layer simultaneously\nunder the water and oil. A detailed methodology to make such lubricant stable\nsurfaces from theoretical perspective was described and experimentally\nvalidated for lubricant stability. Experimental measurements on such surfaces\nshowed extremely low hydrate accumulation and one order of magnitude or more\nreduction in hydrate adhesion force."
    },
    {
        "anchor": "Single active particle engine utilizing a non-reciprocal coupling\n  between particle's position and self-propulsion: We recently argued that a self-propelled particle is formally equivalent to a\nsystem consisting of two subsystems coupled by a non-reciprocal interaction\n[Phys. Rev. E 100, 050603(R) (2019)]. Here we show that this non-reciprocal\ncoupling allows to extract useful work from a single self-propelled particle\nmaintained at constant temperature, by using an aligning interaction to\ninfluence correlations between the particle's position and self-propulsion.",
        "positive": "Semi-Flexible Polymer in a Uniform Force Field in Two Dimensions: The conformational properties of a semi-flexible polymer chain, anchored at\none end in a uniform force field, are studied in a simple two-dimensional\nmodel. Recursion relations are derived for the partition function and then\niterated numerically. We calculate the angular fluctuations of the polymer\nabout the direction of the force field and the average polymer configuration as\nfunctions of the bending rigidity, chain length, chain orientation at the\nanchoring point, and field strength."
    },
    {
        "anchor": "Quantum Mechanics, Path Integrals and Option Pricing: Reducing the\n  Complexity of Finance: Quantum Finance represents the synthesis of the techniques of quantum theory\n(quantum mechanics and quantum field theory) to theoretical and applied\nfinance. After a brief overview of the connection between these fields, we\nillustrate some of the methods of lattice simulations of path integrals for the\npricing of options. The ideas are sketched out for simple models, such as the\nBlack-Scholes model, where analytical and numerical results are compared.\nApplication of the method to nonlinear systems is also briefly overviewed. More\ngeneral models, for exotic or path-dependent options are discussed.",
        "positive": "Interpreting Holographic Molecular Binding Assays with Effective Medium\n  Theory: Holographic molecular binding assays use holographic video microscopy to\ndirectly detect molecules binding to the surfaces of micrometer-scale colloidal\nbeads by monitoring associated changes in the beads' light-scattering\nproperties. Holograms of individual spheres are analyzed by fitting to a\ngenerative model based on the Lorenz-Mie theory of light scattering. Each fit\nyields an estimate of a probe bead's diameter and refractive index with\nsufficient precision to watch the beads grow as molecules bind. Rather than\nmodeling the molecular-scale coating, however, these fits use effective medium\ntheory, treating the coated sphere as if it were homogeneous. This\neffective-sphere analysis is rapid and numerically robust and so is useful for\npractical implementations of label-free immunoassays. Here, we assess how\neffective-sphere properties reflect the properties of molecular-scale coatings\nby modeling coated spheres with the discrete-dipole approximation and analyzing\ntheir holograms with the effective-sphere model."
    },
    {
        "anchor": "Shear-induced laning transition in a confined colloidal film: Using Brownian dynamics (BD) simulations we investigate a dense system of\ncharged colloids exposed to shear flow in a confined (slit-pore) geometry. The\nequilibrium system at zero flow consists of three, well-pronounced layers with\nsquare-like crystalline in-plane structure. We demonstrate that, for\nsufficiently large shear rates, the middle layer separates into two sublayers\nwhere the particles organize into moving lanes with opposite velocities. The\nformation of this micro-laned state results in a destruction of the applied\nshear profile. It has a strong impact not only on the structure of the system,\nbut also on its rheology as measured by the stress tensor. At higher shear\nrates we observe a disordered state and finally a recrystallization reminiscent\nof the behavior of bilayer films. We expect the shear-induced laning to be a\ngeneric feature of thin films with three or more layers.",
        "positive": "Dense granular flow at the critical state: maximum entropy and\n  topological disorder: After extensive quasi-static shearing, dense dry granular flows attain a\nsteady-state condition of porosity and deviatoric stress, even as particles are\ncontinually rearranged. The paper considers two-dimensional flow and derives\nthe probability distributions of two topological measures of particle\narrangement---coordination number and void valence---that maximize topological\nentropy. By only considering topological dispersion, the method closely\npredicts the distribution of void valences, as measured in discrete element\n(DEM) simulations. Distributions of coordination number are also derived by\nconsidering packings that are geometrically and kinetically consistent with the\nparticle sizes and friction coefficient. A cross-entropy principle results in a\ndistribution of coordination numbers that closely fits DEM simulations."
    },
    {
        "anchor": "Strong orientational coupling of block copolymer microdomains to smectic\n  layering revealed by magnetic field alignment: We elucidate the roles of the isotropic-nematic (I-N) and nematic-smectic A\n(N-SmA) transitions in magnetic field directed self-assembly of a liquid\ncrystalline block copolymer (BCP), using \\textit{in situ} x-ray scattering.\nCooling into the nematic from the disordered melt yields poorly ordered and\nweakly aligned BCP microdomains. Continued cooling into the SmA however results\nin an abrupt increase in BCP orientational order with microdomain alignment\ntightly coupled to the translational order parameter of the smectic layers.\nThese results underscore the significance of the N-SmA transition in generating\nhighly aligned states under magnetic fields in these hierarchically ordered\nmaterials.",
        "positive": "'Rocket propulsion' of Janus micro-swimmers: We report simulations of a spherical Janus particle undergoing exothermic\nsurface reactions around one pole only. Our model excludes self-phoretic\ntransport by design. Nevertheless, net motion occurs from direct momentum\ntransfer between solvent and colloid, with speed scaling as the square root of\nthe energy released during the reaction. We find that such propulsion is\ndominated by the system's short-time response, when neither the time dependence\nof the flow around the colloid nor the solvent compressibility can be ignored.\nOur simulations agree reasonably well with previous experiments."
    },
    {
        "anchor": "Mode expansion for the density profile of crystal-fluid interfaces: Hard\n  spheres as a test case: We present a technique for analyzing the full three-dimensional density\nprofiles of a planar crystal-fluid interface in terms of density modes. These\ndensity modes can also be related to crystallinity order parameter profiles\nwhich are used in coarse-grained, phase field type models of the statics and\ndynamics of crystal-fluid interfaces and are an alternative to crystallinity\norder parameters extracted from simulations using local crystallinity criteria.\nWe illustrate our results for the hard sphere system using finely-resolved,\nthree-dimensional density profiles from density functional theory of\nfundamental measure type.",
        "positive": "Kinetics of actin networks formation measured by time resolved\n  particle-tracking microrheology: Actin is one of the most studied cytoskeleton proteins showing a very rich\nspan of structures. It can self-assemble actively into dynamical structures\nthat govern the mechanical properties of the cell, its motility and its\ndivision. However, only very few studies characterize the kinetics of the\nactive actin self-assembly process beyond the formation of an entangled\nnetwork. Here, we follow actin polymerization kinetics and organization into\nentangled networks using time resolved passive microrheology. We establish a\nrelationship between the initial concentration of monomers, the active\npolymerization and network formation kinetics, and the viscoelastic properties\nfrom the onset of actin polymerization upto the formation of a steady state\nentangled network. Surprisingly, we find that at high enough initial monomer\nconcentrations the elastic modulus of the forming actin networks overshoots and\nthen relaxes with a -2/5 power law, that we attribute to rearrangements of the\nnetwork into a steady state structure."
    },
    {
        "anchor": "Homogeneous nucleation of ice: Ice nucleation is a process of great relevance in physics, chemistry,\ntechnology and environmental sciences, much theoretical and experimental\nefforts have been devoted to its understanding, but still it remains a topic of\nintense research. We shed light on this phenomenon by performing atomistic\nbased simulations. Using metadynamics and a carefully designed set of\ncollective variables, reversible transitions between water and ice are able to\nbe simulated. We find that water freezes into a stacking disordered structure\nwith the all-atom TIP4P/Ice model, and the features of the critical nucleus of\nnucleation at the microscopic level are revealed. Our results are in agreement\nwith recent experimental and other theoretical works and confirm that\nnucleation is preceded by a large increase in tetrahedrally coordinated water\nmolecules.",
        "positive": "Programmable Mechanical Metamaterials: We create mechanical metamaterials whose response to uniaxial compression can\nbe programmed by lateral confinement, allowing monotonic, non-monotonic and\nhysteretic behavior. These functionalities arise from a broken rotational\nsymmetry which causes highly nonlinear coupling of deformations along the two\nprimary axes of these metamaterials. We introduce a soft mechanism model which\ncaptures the programmable mechanics, and outline a general design strategy for\nconfined mechanical metamaterials. Finally, we show how inhomogeneous\nconfinement can be explored to create multi stability and giant hysteresis."
    },
    {
        "anchor": "Applications of controlled-flow laser-polarized xenon gas to porous and\n  granular media study: We report initial NMR studies of continuous flow laser-polarized xenon gas,\nboth in unrestricted tubing, and in a model porous media. The study uses Pulsed\nGradient Spin Echo-based techniques in the gas-phase, with the aim of obtaining\nmore sophisticated information than just translational self-diffusion\ncoefficients. Pulsed Gradient Echo studies of continuous flow laser-polarized\nxenon gas in unrestricted tubing indicate clear diffraction minima resulting\nfrom a wide distribution of velocities in the flow field. The maximum velocity\nexperienced in the flow can be calculated from this minimum, and is seen to\nagree with the information from the complete velocity spectrum, or motion\npropagator, as well as previously published images. The susceptibility of gas\nflows to parameters such as gas mixture content, and hence viscosity, are\nobserved in experiments aimed at identifying clear structural features from\necho attenuation plots of gas flow in porous media. Gas-phase NMR scattering,\nor position correlation flow-diffraction, previously clearly seen in the echo\nattenuation data from laser-polarized xenon flowing through a 2 mm glass bead\npack is not so clear in experiments using a different gas mixture. A propagator\nanalysis shows most gas in the sample remains close to static, while a small\nportion moves through a presumably near-unimpeded path at high velocities.",
        "positive": "Effect of dielectric discontinuity on a spherical polyelectrolyte brush: In this paper we perform molecular dynamics simulations of a spherical\npolyelectrolyte brush and counterions in a salt-free medium. The dielectric\ndiscontinuity on the grafted nanoparticle surface is taken into account by the\nmethod of image charges. Properties of the polyelectrolyte brush are obtained\nfor different parameters, including valency of the counterions, radius of the\nnanoparticle, and the brush total charge. The monovalent counterions density\nprofiles are obtained and compared with a simple mean-field theoretical\napproach. The theory allows us to obtain osmotic properties of the system."
    },
    {
        "anchor": "Contact line stability of ridges and drops: Within the framework of a semi-microscopic interface displacement model we\nanalyze the linear stability of sessile ridges and drops of a non-volatile\nliquid on a homogeneous, partially wet substrate, for both signs and arbitrary\namplitudes of the three-phase contact line tension. Focusing on perturbations\nwhich correspond to deformations of the three-phase contact line, we find that\ndrops are generally stable while ridges are subject only to the long-wavelength\nRayleigh-Plateau instability leading to a breakup into droplets, in contrast to\nthe predictions of capillary models which take line tension into account. We\nargue that the short-wavelength instabilities predicted within the framework of\nthe latter macroscopic capillary theory occur outside its range of validity and\nthus are spurious.",
        "positive": "Dynamic coarse-graining of polymer systems using mobility functions: We propose a dynamic coarse-graining (CG) scheme for mapping heterogeneous\npolymer fluids onto extremely CG models in a dynamically consistent manner. The\nidea is to use as target function for the mapping a wave-vector dependent\nmobility function derived from the single-chain dynamic structure factor, which\nis calculated in the microscopic reference system. In previous work, we have\nshown that dynamic density functional calculations based on this mobility\nfunction can accurately reproduce the order/disorder kinetics in polymer melts,\nthus it is a suitable starting point for dynamic mapping. To enable the mapping\nover a range of relevant wave vectors, we propose to modify the CG dynamics by\nintroducing internal friction parameters that slow down the CG monomer dynamics\non local scales, without affecting the static equilibrium structure of the\nsystem. We illustrate and discuss the method using the example of infinitely\nlong linear Rouse polymers mapped onto ultrashort CG chains. We show that our\nmethod can be used to construct dynamically consistent CG models for\nhomopolymers with CG chain length N=4, whereas for copolymers, longer CG chain\nlengths are necessary"
    },
    {
        "anchor": "Perspectives on opportunities in experimental soft-matter science: Soft materials consist of basic units that are significantly larger than an\natom but much smaller than the overall dimensions of the sample. The label\n\"soft condensed matter\" emphasizes that the large basic building blocks of\nthese materials produce low elastic moduli that govern a material's ability to\nwithstand deformations. Aside from softness, there are many other properties\nthat are also caused by the large size of the constituent building blocks. Soft\nmatter is dissipative, disordered, far-from-equilibrium, non-linear, thermal\nand entropic, slow, observable, gravity-affected, patterned, non-local,\ninterfacially elastic and active. This is only a partial list of how matter\ncreated from large component particles is distinct from \"hard matter\" composed\nof constituents at an atomic scale. Issues inherent in soft matter raise\nproblems that are broadly important in diverse areas of science and require\nmultiple modes of attack. For example, far-from-equilibrium behavior is\nconfronted in biology, chemistry, geophysics, astrophysics and nuclear physics.\nSimilarly, issues dealing with disorder appear broadly throughout many branches\nof inquiry wherever rugged landscapes are invoked. This article reviews the\ndiscussions that occurred during a workshop held on January 30-31, 2016 in\nwhich opportunities in soft-matter experiment were surveyed. Soft matter has\nhad an exciting history of discovery and continues to be a fertile ground for\nfuture research.",
        "positive": "Electrooptic response of chiral nematic with oblique helicoidal director: Electrically induced reorientation of liquid crystals (LCs) is a fundamental\nphenomenon widely used in modern technologies. We observe experimentally an\nelectro-optic effect in a cholesteric LC with a distinct oblique-helicoidal\ndirector deformation. The oblique helicoid, predicted in late 1960-ies, is made\npossible by recently developed dimer materials with an anomalously small bend\nelastic constant. Theoretical, numerical, and experimental analysis establishes\nthat both the pitch and the cone angle of the oblique helicoid increase as the\nelectric field decreases. At low fields, the oblique helicoid with the axis\nparallel to the field transforms into a right-angle helicoid (the ground state\nof field-free cholesteric) with the axis perpendicular to the field."
    },
    {
        "anchor": "Rubber Elasticity: Solution of the James-Guth Model: The solution of the many-body statistical mechanical theory of elasticity\nformulated by James and Guth in the 1940s is presented. The remarkable aspect\nof the solution is that it gives an elastic free energy that is essentially\nequivalent to that developed by Flory over a period of several decades.",
        "positive": "Glass Transition in Supercooled Liquids with Medium Range Crystalline\n  Order: The origins of rapid dynamical slow down in glass forming liquids in the\ngrowth of static length scales, possibly associated with identifiable\nstructural ordering, is a much debated issue. Growth of medium range\ncrystalline order (MRCO) has been observed in various model systems to be\nassociated with glassy behaviour. Such observations raise the question about\nthe eventual state reached by a glass former, if allowed to relax for\nsufficiently long times. Is a slowly growing crystalline order responsible for\nslow dynamics? Are the molecular mechanisms for glass transition in liquids\nwith and without MRCO the same? If yes, glass formers with MRCO provide a\nparadigm for understanding glassy behaviour generically. If not, systems with\nMRCO form a new class of glass forming materials whose molecular mechanism for\nslow dynamics may be easier to understand in terms of growing crystalline\norder, and should be approached in that manner, even while they will not\nprovide generic insights. In this study we perform extensive molecular dynamics\nsimulations of a number of glass forming liquids in two dimensions and show\nthat the static and dynamic properties of glasses with MRCO are different from\nother glass forming liquids with no predominant local order. We also resolve an\nimportant issue regarding the so-called Point-to-set method for determining\nstatic length scales, and demonstrate it to be a robust, order agnostic, method\nfor determining static correlation lengths in glass formers."
    },
    {
        "anchor": "Structural (dis)order and dynamic propensity in a mildly undercooled\n  glass-forming liquid: Spatial correlations and the role of crystalline\n  environments: We use the isoconfigurational (IC) ensemble to show the connection between\nemerging heterogeneities in the tetrahedral order parameter and the dynamic\npropensity in a mildly undercooled glass-forming liquid. We observe that\nspatially correlated tetrahedrally-(dis)ordered clusters of molecules are\nobservable on the time scale of structural relaxation. The heterogeneities of\ntetrahedrally-(dis)ordered clusters correlate with dynamical heterogeneities\n(DH) and these correlations reach peaks at similar time scales. We discover\nthat the angular component of the tetrahedral order parameter is strongly\ncorrelated to the dynamics compared to the radial component. Moreover, these\ncorrelations between the dynamics and tetrahedrally-(dis)ordered regions\nenormously influence the system, with spatial correlations being observable for\na prolonged period beyond the peaks of maximum DH. Further, we discover that\nthe crystalline particle environments in our water model (as identified by the\nIC ensemble) may be the origin for slow dynamics of dynamical heterogeneity in\nour undercooled model water system.",
        "positive": "Theory of Charge Regulation of Colloidal Particles in Electrolyte\n  Solutions: We present a theory that enables us to calculate the effective surface charge\nof colloidal particles and to efficiently obtain titration curves for different\nsalt concentrations. The theory accounts for the shift of pH of solution due to\nthe presence of 1:1 electrolyte. It also accounts self-consistently for the\nelectrostatic potential produced by the deprotonated surface groups. To examine\nthe accuracy of the theory we have performed extensive reactive Monte Carlo\nsimulations, which show excellent agreement between theory and simulations\nwithout any adjustable parameters."
    },
    {
        "anchor": "Fluids with quenched disorder: Scaling of the free energy barrier near\n  critical points: In the context of Monte Carlo simulations, the analysis of the probability\ndistribution $P_L(m)$ of the order parameter $m$, as obtained in simulation\nboxes of finite linear extension $L$, allows for an easy estimation of the\nlocation of the critical point and the critical exponents. For Ising-like\nsystems without quenched disorder, $P_L(m)$ becomes scale invariant at the\ncritical point, where it assumes a characteristic bimodal shape featuring two\noverlapping peaks. In particular, the ratio between the value of $P_L(m)$ at\nthe peaks ($P_{L, max}$) and the value at the minimum in-between ($P_{L, min}$)\nbecomes $L$-independent at criticality. However, for Ising-like systems with\nquenched random fields, we argue that instead $\\Delta F_L := \\ln (P_{L, max} /\nP_{L, min}) \\propto L^\\theta$ should be observed, where $\\theta>0$ is the\n\"violation of hyperscaling\" exponent. Since $\\theta$ is substantially non-zero,\nthe scaling of $\\Delta F_L$ with system size should be easily detectable in\nsimulations. For two fluid models with quenched disorder, $\\Delta F_L$ versus\n$L$ was measured, and the expected scaling was confirmed. This provides further\nevidence that fluids with quenched disorder belong to the universality class of\nthe random-field Ising model.",
        "positive": "Hydrodynamics of a disk in a thin film of weakly nematic fluid subject\n  to linear friction: To make progress towards the development of a theory on the motion of\ninclusions in thin structured films and membranes, we here consider as an\ninitial step a circular disk in a two-dimensional, uniaxially anisotropic fluid\nlayer. We assume overdamped dynamics, incompressibility of the fluid, and\nglobal alignment of the axis of anisotropy. Motion within this layer is\naffected by additional linear friction with the environment, for instance, a\nsupporting substrate. We investigate the induced flows in the fluid when the\ndisk is translated parallel or perpendicular to the direction of anisotropy.\nMoreover, expressions for corresponding mobilities and resistance coefficients\nof the disk are derived. Our results are obtained within the framework of a\nperturbative expansion in the parameters that quantify the anisotropy of the\nfluid. Good agreement is found for moderate anisotropy when compared to\nassociated results from finite-element simulations. At pronounced anisotropy,\nthe induced flow fields are still predicted qualitatively correctly by the\nperturbative theory, although quantitative deviations arise. We hope to\nstimulate with our investigations corresponding experimental analyses, for\nexample, concerning fluid flows in anisotropic thin films on uniaxially rubbed\nsupporting substrates."
    },
    {
        "anchor": "Internal structure and swelling behaviour of in silico microgel\n  particles: Microgels are soft colloids that, in virtue of their polymeric nature, can\nreact to external stimuli such as temperature or pH by changing their size. The\nresulting swelling/deswelling transition can be exploited in fundamental\nresearch as well as for many diverse practical applications, ranging from art\nrestoration to medicine. Such an extraordinary versatility stems from the\ncomplex internal structure of the individual microgels, each of which is a\ncrosslinked polymer network. Here we employ a recently-introduced computational\nmethod to generate realistic microgel configurations and look at their\nstructural properties, both in real and Fourier space, for several temperatures\nacross the volume phase transition as a function of the crosslinker\nconcentration and of the confining radius employed during the `in-silico'\nsynthesis. We find that the chain-length distribution of the resulting networks\ncan be analytically predicted by a simple theoretical argument. In addition, we\nfind that our results are well-fitted to the fuzzy-sphere model, which\ncorrectly reproduces the density profile of the microgels under study.",
        "positive": "Activation Volume in the Density Scaling Regime: Equation of State and\n  Its Test by Using Experimental and Simulation Data: In this paper, a formalism for the activation volume of glass forming\nmaterials is suggested. An isothermal equation of state for the activation\nvolume is formulated, which is extended to a generalized equation of state that\ndescribes the activation volume as a function of temperature and pressure. Both\nthe equations of state are very successfully validated by using experimental\nand simulation data collected for supercooled Kob-Andersen binary Lennard-Jones\nliquid and materials from various material groups such as van der Waals\nliquids, polymers, protic ionic liquids, and strongly hydrogen bonded liquids.\nSome predictions based on these equations of state for the activation volume\nare also very satisfactorily verified in case of each considered system,\nespecially a kind of the activation volume scaling with the scaling exponent\nthat also constitutes the slope of the expected linear pressure dependence of\nthe isothermal bulk modulus for the activation volume is confirmed. The until\nrecently unexpected negative value of the slope are explained in case of the\nsystems that obey the thermodynamic scaling law at least to a good\napproximation."
    },
    {
        "anchor": "Scissors mode and superfluidity of a trapped Bose-Einstein condensed gas: We investigate the oscillation of a dilute atomic gas generated by a sudden\nrotation of the confining trap (scissors mode). This oscillation reveals the\neffects of superfluidity exhibited by a Bose-Einstein condensate. The scissors\nmode is investigated also in a classical gas above T_c in various collisional\nregimes. The crucial difference with respect to the superfluid case arises from\nthe occurence of low frequency components, which are responsible for the rigid\nvalue of the moment of inertia. Different experimental procedures to excite the\nscissors mode are discussed.",
        "positive": "Microbial range expansions on liquid substrates: Despite the importance that fluid flow plays in transporting and organizing\npopulations, few laboratory systems exist to systematically investigate the\nimpact of advection on their spatial evolutionary dynamics. To address this\nproblem, we study the morphology and genetic spatial structure of microbial\ncolonies growing on the surface of a nutrient-laden fluid $10^4$ to $10^5$\ntimes more viscous than water in Petri dishes, the extreme but finite viscosity\ninhibits undesired thermal convection and allows populations to effectively\nlive at the air-liquid interface due to capillary forces. We discover that S.\ncerevisiae (baker's yeast) growing on a viscous liquid behave like \"active\nmatter\": they metabolically generate fluid flows many times larger than their\nunperturbed colony expansion speed, and that flow, in return, can dramatically\nimpact their colony morphology and spatial population genetics. We show that\nyeast cells generate fluid flows by consuming surrounding nutrients and\ndecreasing the local substrate density, leading to misaligned fluid pressure\nand density contours, which ultimately generates vorticity via a thresholdless\nbaroclinic instability. Numerical simulations demonstrate that an intense\nvortex ring is produced below the colony's edge and quantitatively predict the\nobserved flow. As the viscosity of the substrate is lowered and the\nself-induced flow intensifies, we observe three distinct morphologies: at the\nhighest viscosity,compact circular colonies similar to those grown on hard agar\nplates except with a stretched regime of exponential expansion, intermediate\nviscosities give rise to compact colonies with \"fingers\" that are ripped away\nto break into smaller cell clusters, and at the lowest viscosity, the expanding\ncolony breaks up into many genetically-diverse, mutually repelling, island-like\nfragments of yeast colonies."
    },
    {
        "anchor": "Crystallization mechanism in melts of short n-alkane chains: We study crystallization in a model system for eicosane (C20) by means of\nmolecular dynamics simulation and we identify the microscopic mechanisms of\nhomogeneous crystal nucleation and growth. For the nucleation process, we\nobserve that chains first align and then straighten. Then the local density\nincreases and finally the monomer units become ordered positionally. The\nsubsequent crystal growth process is characterized by a sliding-in motion of\nthe chains. Chains preferably attach to the crystalline cluster with one end\nand then move along the stems of already crystallized chains towards their\nfinal position. This process is cooperative, i.e. neighboring chains tend to\nget attached in clusters rather than independently",
        "positive": "Impact of elastic heterogeneity on the propagation of vibrations at\n  finite temperatures in glasses: Some aspects of how sound waves travel through disordered solids are still\nunclear. Recent work has characterized a feature of disordered solids which\nseems to influence vibrational excitations at the mesoscales, local elastic\nheterogeneity. Sound waves propagation has been demonstrated to be strongly\naffected by inhomogeneous mechanical features of the materials which add to the\nstandard anharmonic couplings, amounting to extremely complex transport\nproperties at finite temperatures. Here, we address these issues for the case\nof a simple atomic glass former, by Molecular Dynamics computer simulation. In\nparticular, we focus on the transverse components of the vibrational\nexcitations in terms of dynamic structure factors, and characterize the\ntemperature dependence of sound dispersion and attenuation in an extended\nfrequency range. We provide a complete picture of how elastic heterogeneity\ndetermines transport of vibrational excitations, also based on a direct\ncomparison of the numerical data with the predictions of the heterogeneous\nelastic theory."
    },
    {
        "anchor": "Small membranes under negative surface tension: We use computer simulations and a simple free energy model to study the\nresponse of a bilayer membrane to the application of a negative (compressive)\nmechanical tension. Such a tension destabilizes the long wavelength undulation\nmodes of giant vesicles, but it can be sustained when small membranes and\nvesicles are considered. Our negative tension simulation results reveal two\nregimes - (i) a weak negative tension regime characterized by\nstretching-dominated elasticity, and (ii) a strong negative tension regime\nfeaturing bending-dominated elastic behavior. This resembles the findings of\nthe classic Evans and Rawicz micropipette aspiration experiment in giant\nunilamellar vesicles (GUVs) [Phys, Rev. Lett. {\\bf 64}, 2094 (1990)]. However,\nwhile in GUVs the crossover between the two elasticity regimes occurs at a\nsmall positive surface tension, in smaller membranes it takes place at a\nmoderate negative tension. Another interesting observation concerning the\nresponse of a small membrane to negative surface tension is related to the\nrelationship between the mechanical and fluctuation tensions, which are equal\nto each other for non-negative values. When the tension decreases to negative\nvalues, the fluctuation tension $\\gamma$ drops somewhat faster than $\\tau$ in\nthe small negative tension regime, before it saturates (and becomes larger than\n$\\tau$) for large negative tensions. The bending modulus exhibit an \"opposite\"\ntrend. It remains almost unchanged in the stretching-dominated elastic regime,\nand decreases in the bending-dominated regime. Both the amplitudes of the\nthermal height undulations and the projected area variations diverge at the\nonset of mechanical instability.",
        "positive": "Transverse viscous transport in classical solids: The transverse velocity time correlation function ${\\tilde C}_{\\rm\nT}(k,\\omega)$ with $k$ and $\\omega$ being the wavenumber and the frequency,\nrespectively, is a fundamental quantity in determining the transverse\nmechanical and transport properties of materials. In ordinary liquids, a\nnonzero value of ${\\tilde C}_{\\rm T}(k,0)$ is inevitably associated with\nviscous material flows. Curiously, even in solids where significant material\nflows are precluded due to frozen positional degrees of freedom, molecular\ndynamics simulations reveal that ${\\tilde C}_{\\rm T}(k,0)$ certainly takes a\nnonzero value, and in consequence, the time integration of the velocity field\nshows definite diffusive behavior with diffusivity ${\\tilde C}_{\\rm T}(k,0)/3$.\nWe demonstrate that this diffusive behavior can be attributed to a\nsolid-specific viscous transport. The resultant viscosity is interpreted as the\nrenormalized viscosity accounting for the nonlinear inertia effect."
    },
    {
        "anchor": "Topological edge floppy modes in disordered fiber networks: Disordered fiber networks are ubiquitous in a broad range of natural (e.g.,\ncytoskeleton) and manmade (e.g., aerogels) materials. In this paper, we discuss\nthe emergence of topological floppy edge modes in these fiber networks as a\nresult of deformation or active driving. It is known that a network of straight\nfibers exhibits bulk floppy modes which only bend the fibers without stretching\nthem. We find that, interestingly, with a perturbation in geometry, these bulk\nmodes evolve into edge modes. We introduce a topological index for these edge\nmodes and discuss their implications in biology.",
        "positive": "Extending the analogy between intracellular motion in mammalian cells\n  and glassy dynamics: The physics of how molecules, organelles, and foreign objects move within\nliving cells has been extensively studied in organisms ranging from bacteria to\nhuman cells. In mammalian cells, in particular, cellular vesicles move across\nthe cell using motor proteins that carry the vesicle down the cytoskeleton to\ntheir destination. We have recently noted several similarities between the\nmotion of such vesicles and that in disordered, \"glassy\", systems, but it\nremains unclear whether that is a general observation or something specific to\ncertain vesicles in one particular cell type. Here we follow the motion of\nmitochondria, the organelles responsible for cell energy production, in several\nmammalian cell types over timescales ranging from 50 ms up to 70 s. Qualitative\nobservations show that single mitochondria remain stalled, remaining within a\nspatially limited region, for extended periods of time, before moving longer\ndistances relatively quickly. Analysing this motion quantitatively, we observe\na displacement distribution that is roughly Gaussian for shorter distances\n($\\lesssim$ 0.05 $\\mu$m) but which exhibits exponentially decaying tails at\nlonger distances (up to 0.40 $\\mu$m). We show that this behaviour is\nwell-described by a model originally developed to describe the motion in glassy\nsystems. These observations are extended to in total 3 different objects\n(mitochondria, lysosomes and nano-sized beads enclosed in vesicles), 3\ndifferent mammalian cell types, from 2 different organisms (human and mouse).\nWe provide further evidence that supports glass-like characteristics of the\nmotion by showing a difference between the time it takes to move a longer\ndistance for the first time and subsequent times, as well as a weak ergodicity\nbreaking of the motion. Overall, we demonstrate the ubiquity of glass-like\nmotion in mammalian cells, providing a different perspective on intracellular\nmotion."
    },
    {
        "anchor": "Collective motion of driven semiflexible filaments tuned by soft\n  repulsion and stiffness: In active matter systems, self-propelled particles can self-organize to\nundergo collective motion, leading to persistent dynamical behavior out of\nequilibrium. In cells, cytoskeletal filaments and motor proteins self-organize\ninto complex structures important for cell mechanics, motility, and division.\nCollective dynamics of cytoskeletal systems can be reconstituted using filament\ngliding experiments, in which cytoskeletal filaments are propelled by\nsurface-bound motor proteins. These experiments have observed diverse dynamical\nstates, including flocks, polar streams, and single-filament spirals. Recent\nexperiments with microtubules and kinesin motor proteins found that the\ncollective behavior of filaments can be tuned by altering the concentration of\nthe crowding macromolecule methylcellulose in solution. Increasing the\nmethycellulose concentration reduced filament crossing, promoted alignment, and\nled to a transition from active, isotropically oriented filaments to locally\naligned polar streams. This emergence of collective motion is typically\nexplained as an increase in alignment interactions by Vicsek-type models of\nactive polar particles. However, it is not yet understood how steric\ninteractions and bending stiffness modify the collective behavior of active\nfilaments. We use simulations of driven filaments with tunable soft repulsion\nand rigidity in order to better understand how the interplay between filament\nflexibility and steric effects can lead to different active dynamic states. We\nfind that increasing filament stiffness decreases the probability of filament\nalignment, yet increases collective motion and long-range order, in contrast to\nthe assumptions of a Vicsek-type model. In addition to repulsion and driving,\ntuning filament stiffness can promote collective behavior, and controls the\ntransition between active isotropic filaments, locally aligned flocks, and\npolar streams.",
        "positive": "Mixing Twist-Bend and Ferroelectric nematic liquid crystals: Twist-bend (Ntb) and ferroelectric (NF) nematic liquid crystals exhibit\nseveral novel effects and new physical properties. The question of what happens\nin binary mixtures is interesting as a matter of curiosity and pure science.\nHere, we report experimental studies on the phase diagram and some physical\nproperties of binary mixtures of the above-mentioned nematic liquid crystals.\nBoth N-Ntb and N-NF phase transition temperatures and the corresponding\nenthalpies decrease significantly and eventually, these transitions disappear\nin some intermediate compositions. Temperature dependent birefringence above\nthe N-Ntb phase transition temperature shows critical behaviour, and the\ncritical range of the tilt fluctuations becomes wider in the mixtures. The\nmagnitudes and the temperature dependence of the splay elastic constant of the\nmixtures' high-temperature nematic (N) phase strikingly differ from that of the\npristine twist-bend and ferroelectric nematic liquid crystals. The study shows\nthat Ntb and NF liquid crystals are incompatible."
    },
    {
        "anchor": "General elastic interaction in nematic liquid crystals colloids: The new free energy functional that describes general elastic interaction\nbetween colloidal particles and nematic liquid crystal has been proposed. It\ngeneralizes results of the paper \\cite{lupe} on the case of arbitrary\norientation of colloidal particles and is valid for arbitrary surface anchoring\nstrength. Formal analogies and differences between electric particles and\ncolloidal particles in LC are found. It is first time shown that spur of the\nquadrupole moment tensor is different from zero $Sp\\hat{Q}_{\\mu}\\neq 0$ in the\ncase of axial symmetry breaking of the director field around colloidal particle\nin contrast to electrostatics. New general presentation for the elastic\ninteraction between arbitrary colloids is obtained which contains new multipole\nterms connected with $Sp\\hat{Q}_{\\mu}\\neq 0$ that are absent in the standard\nelectrostatics.",
        "positive": "On the density of shear transformation zones in amorphous solids: We study the stability of amorphous solids, focusing on the distribution P(x)\nof the local stress increase x that would lead to an instability. We argue that\nthis distribution is singular P(x)x^{\\theta}, where the exponent {\\theta} is\nnon-zero if the elastic interaction between rearranging regions is\nnon-monotonic, and increases with the interaction range. For a class of finite\ndimensional models we show that stability implies a lower bound on {\\theta},\nwhich is found to lie near saturation. For quadrupolar interactions these\nmodels yield {\\theta} ~ 0.6 for d=2 and \\theta ~ 0.4 in d=3 where d is the\nspatial dimension, accurately capturing previously unresolved observations in\natomistic models, both in quasi-static flow and after a fast quench."
    },
    {
        "anchor": "Biaxial nematic and smectic phases of parallel particles with different\n  cross sections: We have calculated the phase diagrams of one--component fluids made of five\ntypes of biaxial particles differing in their cross sections. The orientation\nof the principal particle axis is fixed in space, while the second axis is\nallowed to freely rotate. We have constructed a free-energy density functional\nbased on fundamental--measure theory to study the relative stability of nematic\nand smectic phases with uniaxial, biaxial and tetratic symmetries. Minimization\nof the density functional allows us to study the phase behavior of the biaxial\nparticles as a function of the cross-section geometry. For low values of the\naspect ratio of the particle cross section, we obtain smectic phases with\ntetratic symmetry, although metastable with respect to the crystal, as our MC\nsimulation study indicates. For large particle aspect ratios and in analogy\nwith previous work [Phys. Chem. Chem. Phys. 5, 3700 (2003)], we have found a\nfour--phase point where four spinodals, corresponding to phase transitions\nbetween phases with different symmetries, meet together. The location of this\npoint is quite sensitive to particle cross section, which suggests that\noptimizing the particle geometry could be a useful criterion in the design of\ncolloidal particles that can exhibit an increased stability of the biaxial\nnematic phase with respect to other competing phases with spatial order.",
        "positive": "Dynamical Effective Field Model for Interacting Ferrofluids: I.\n  Derivations for homogeneous, inhomogeneous, and polydisperse cases: Quite recently I have proposed a nonperturbative dynamical effective field\nmodel (DEFM) to quantitatively describe the dynamics of interacting\nferrofluids. Its predictions compare very well with the results from\nsimulations. In this paper I put the DEFM on firm theoretical ground by\nderiving it within the framework of dynamical density functional theory (DDFT),\nin which the relevant part of correlation-induced free energy is approximated\nby a function of the instantaneous magnetization. The DEFM is generalized to\ninhomogeneous finite-size samples for which the macroscopic and mesoscopic\nscale separation is nontrivial due to the presence of long-range dipole-dipole\ninteractions. The demagnetizing field naturally emerges from microscopic\nconsiderations and is consistently accounted for. The resulting particle\ndynamics on the mesoscopic scale only involves macroscopically local quantities\nsuch as local magnetization and Maxwell field. Nevertheless, the local\ndemagnetizing field essentially couples to magnetization at distant macroscopic\nlocations. Thus, a two-scale parallel algorithm, involving information transfer\nbetween different macroscopic locations, can be applied to fully resolve\nparticle rotational dynamics in an inhomogeneous sample. I also derive the DEFM\nfor polydisperse ferrofluids, in which the dynamics of particles belonging to\ndifferent species can be strongly coupled to each other. I discuss the\nunderlying assumptions in obtaining a thermodynamically consistent polydisperse\nmagnetization relaxation equation, which is of the same generic form as that\nfor monodisperse ferrofluids. The theoretical advances presented in this paper\nare important for both qualitative understanding and quantitative modeling of\nferrofluid dynamics."
    },
    {
        "anchor": "Glass transition in systems without static correlations: a microscopic\n  theory: We present a first step toward a microscopic theory for the glass transition\nin systems with trivial static correlations. As an example we have chosen N\ninfinitely thin hard rods with length L, fixed with their centers on a periodic\nlattice with lattice constant a. Starting from the N-rod Smoluchowski equation\nwe derive a coupled set of equations for fluctuations of reduced k-rod\ndensities. We approximate the influence of the surrounding rods onto the\ndynamics of a pair of rods by introduction of an effective rotational diffusion\ntensor D and in this way we obtain a self-consistent equation for D. This\nequation exhibits a feedback mechanism leading to a slowing down of the\nrelaxation. It involves as an input the Laplace transform v_0(l/r) at z=0,\nl=L/a, of a torque-torque correlator of an isolated pair of rods with distance\nR=ar. Our equation predicts the existence of a continuous ergodicity-breaking\ntransition at a critical length l_c=L_c/a. To estimate the critical length we\nperform an approximate analytical calculation of v_0(l/r) based on a\nvariational approach and obtain l_c^{var}=5.68, 4.84 and 3.96 for an sc, bcc\nand fcc lattice. We also evaluate v_0(l/r) numerically exactly from a two-rod\nsimulation. The latter calculation leads to l_c^{num}=3.45, 2.78 and 2.20 for\nthe corresponding lattices. Close to l_c the rotational diffusion constant\ndecreases as D(l) ~ (l_c - l)^\\gamma with \\gamma=1 and a diverging time scale\nt_\\epsilon ~ |l_c - l|^{-\\delta}, \\delta=2, appears. On this time scale the t-\nand l-dependence of the 1-rod density is determined by a master function\ndepending only on t/t_\\epsilon. In contrast to present microscopic theories our\napproach predicts a glass transition despite the absence of any static\ncorrelations.",
        "positive": "High-resolution structure of coexisting nanoscopic and microscopic lipid\n  domains: We advanced a previously reported model for the \\textit{in situ} scattering\ndata analysis of coexisting lipid domains in free-floating multilamellar\nvesicles. Based on the scattering density profile of the individual domains we\nconsidered in particular modifications due to positionally anticorrelated\ndomains or the presence of cholesterol. The latter aspect can be easily\nextended to any other lipophilic molecule. This allowed us to retrieve elastic\nand structural details (bending fluctuations, domain thickness, area per lipid)\nof coexisting liquid-ordered/liquid-disordered domains, including the\npartitioning of cholesterol from small-angle x-ray scattering experiments.\nMoreover, the model also successfully fitted data of multilamellar vesicles\nexhibiting nanoscopic domains, which displayed unlike coexisting micron-sized\ndomains no clear signal for two lamellar lattices. Our results indicate a\npreviously not observed translation of cholesterol toward the bilayer center of\nnanoscopic liquid-ordered domains."
    },
    {
        "anchor": "A hybrid particle-continuum method for hydrodynamics of complex fluids: A previously-developed hybrid particle-continuum method [J. B. Bell, A.\nGarcia and S. A. Williams, SIAM Multiscale Modeling and Simulation,\n6:1256-1280, 2008] is generalized to dense fluids and two and three dimensional\nflows. The scheme couples an explicit fluctuating compressible Navier-Stokes\nsolver with the Isotropic Direct Simulation Monte Carlo (DSMC) particle method\n[A. Donev and A. L. Garcia and B. J. Alder, ArXiv preprint 0908.0510]. To\nachieve bidirectional dynamic coupling between the particle (microscale) and\ncontinuum (macroscale) regions, the continuum solver provides state-based\nboundary conditions to the particle subdomain, while the particle solver\nprovides flux-based boundary conditions for the continuum subdomain. The\nequilibrium diffusive (Brownian) motion of a large spherical bead suspended in\na particle fluid is examined, demonstrating that the hybrid method correctly\nreproduces the velocity autocorrelation function of the bead but only if\nthermal fluctuations are included in the continuum solver. Finally, the hybrid\nis applied to the well-known adiabatic piston problem and it is found that the\nhybrid correctly reproduces the slow non-equilibrium relaxation of the piston\ntoward thermodynamic equilibrium but, again, only the continuum solver includes\nstochastic (white-noise) flux terms. These examples clearly demonstrate the\nneed to include fluctuations in continuum solvers employed in hybrid multiscale\nmethods.",
        "positive": "Structural dynamics of a model of amorphous silicon: We perform extensive simulations and systematic statistical analyses of the\nstructural dynamics of amorphous silicon. The simulations follow the dynamics\nintroduced by Wooten, Winer and Weaire: the energy is obtained with the Keating\npotential, and the dynamics consists of bond transpositions proposed at random\nlocations and accepted with the Metropolis acceptance ratio. The structural\nquantities we track are the variations in time of the lateral lengths\n($L_x$,$L_y$,$L_z$) of the cuboid simulation cell. We transform these\nquantities into the volume $V$ and two aspect ratios $B_1$ and $B_2$. Our\nanalysis reveals that at short times, the mean squared displacement (MSD) for\nall of them exhibits normal diffusion. At longer times, they cross over to\nanomalous diffusion, with a temperature-dependent anomalous exponent\n$\\alpha<1$. We analyze our findings in the light of two standard models in\nstatistical physics that feature anomalous dynamics, $viz.$, continuous time\nrandom walker (CTRW) and fractional Brownian motion (fBm). We obtain the\ndistribution of waiting times, and find that the data are consistent with a\nstretched-exponential decay. We also show that the three quantities, $V$, $B_1$\nand $B_2$ exhibit negative velocity autocorrelation functions. These\nobservations together suggest that the dynamics of the material belong to the\nfBm class."
    },
    {
        "anchor": "Rotation and propulsion in 3d active chiral droplets: Chirality is a recurrent theme in the study of biological systems, in which\nactive processes are driven by the internal conversion of chemical energy into\nwork. Bacterial flagella, acto-myosin filaments and microtubule bundles are\nactive systems which are also intrinsically chiral. Despite some exploratory\nattempt to capture the relations between chirality and motility, no\nintrinsically chiral system has ever been analyzed so far. To address this gap\nin knowledge, here we study the effects of internal active forces and torques\non a three-dimensional droplet of cholesteric liquid crystal (CLC) embedded in\nan isotropic liquid. We consider tangential anchoring of the liquid crystal\ndirector at the droplet surface. Contrary to what happens in nematics, where\nmoderate extensile activity leads to droplet rotation, cholesteric active\ndroplets exhibit a lot more complex and variegated behaviors. We find that\nextensile force dipole activity stabilises complex defect configurations whose\norbiting dynamics couples to thermodynamic chirality to propel screw-like\ndroplet motion. Instead, dipolar torque activity may either tighten or unwind\nthe cholesteric helix, and if tuned can power rotations with an oscillatory\nangular velocity of zero mean.",
        "positive": "The SIRAH force-field and interactions between short DNA duplexes: In recent years, short DNA duplexes have been studied as an interesting\nself-assembling system and a building block for DNA-based nanotechnologies.\nNumerical simulation studies for the determination of the full phase diagram of\nshort duplexes require, as an input ingredient, a simplified but reliable\nforce-field able to capture the main features of duplex-duplex interaction. We\nused the coarse-grained SIRAH force field in the implicit solvent approximation\nto study the interaction between two short duplexes of double-strand DNA as a\nfunction of the relative positions and orientations and the salt concentration,\nin the cases of 8 and 20 base pairs. We discuss the consequences of our study\nto determine new simple but qualitatively reliable model potentials."
    },
    {
        "anchor": "Concentration-Temperature Superposition of Helix Folding Rates in\n  Gelatin: We study the kinetics of helix-coil transition in water solutions of gelatin\n(collagen protein) by optical rotation techniques combined with thermal\ncharacterization. By examining the rates of secondary helix folding, and\ncovering a very wide range of solution concentrations, we are able to identify\na universal exponential dependence of folding rate on concentration and quench\ntemperature. We demonstrate a new concentration-temperature superposition of\ndata at all temperatures and concentrations, and build the corresponding master\ncurve. The results support the concept of a diffuse helix-coil transition. We\nfind no concentration dependance of the normalized rate constant, suggesting\nfirst order (single) kinetics of secondary helix folding dominate in the early\nstages of renaturation.",
        "positive": "Diffusion of Chiral Janus Particles in Convection Rolls: The diffusion of an artificial active particle in a two-dimensional periodic\npattern of stationary convection cells is investigated by means of extensive\nnumerical simulations. In the limit of large P\\'eclet numbers, i.e., for\nself-propulsion speeds below a certain depinning threshold and weak\nroto-translational fluctuations, the particle undergoes asymptotic normal\ndiffusion with diffusion constant proportional to the square root of its\ndiffusion constant at zero flow. Chirality effects in the propulsion mechanism,\nmodeled here by a tunable applied torque, favors particle's jumping between\nadjacent convection rolls. Roll jumping is signaled by an excess diffusion\npeak, which appears to separate two distinct active diffusion regimes for low\nand high chirality. A qualitative interpretation of our simulation results is\nproposed as a first step toward a fully analytical study of this phenomenon."
    },
    {
        "anchor": "Director precession and nonlinear waves in nematic liquid crystals under\n  elliptic shear: Elliptic shear applied to a homeotropically oriented nematic above the\nelectric bend Freedericks transition (FT) generates slow precession of the\ndirector. The character of the accompanying nonlinear waves changes from\ndiffusive phase waves to dispersive ones exhibiting spirals and spatio-temporal\nchaos as the FT is approached from above. An exact solution of the flow\nalignment equations captures the observed precession and predicts its reversal\nfor non-flow aligning materials. The FT transforms into a Hopf bifurcation\nopening the way to understand the wave phenomena.",
        "positive": "Statistical field theory for a multicomponent fluid: The collective\n  variables approach: Using the collective variables (CV) method the basic relations of statistical\nfield theory of a multicomponent non-homogeneous fluids are reconsidered. The\ncorresponding CV action depends on two sets of scalar fields - fields\n$\\rho_{\\alpha}$ connected to the local density fluctuations of the $\\alpha$th\nspecies of particles and fields $\\omega_{\\alpha}$ conjugated to\n$\\rho_{\\alpha}$. The explicit expressions for the CV field correlations and\ntheir relation to the density correlation functions are found. The perturbation\ntheory is formulated and a mean field level (MF) of the theory is considered in\ndetail."
    },
    {
        "anchor": "Surveying the Free Energy Landscapes of Continuum Models: Application to\n  Soft Matter Systems: A variety of methods are developed for characterising the free energy\nlandscapes of continuum, Landau-type free energy models. Using morphologies of\nlipid vesicles and a multistable liquid crystal device as examples, I show that\nthe methods allow systematic study of not only the most relevant minimum energy\nconfigurations, but also the transition pathways between any two minima, as\nwell as their corresponding energy barriers and transition state\nconfigurations. A global view of the free energy landscapes can then be\nvisualized using either a disconnectivity graph or a network representation.\nDifferent forms of free energy functionals and boundary conditions can be\nreadily implemented, thus allowing these tools to be utilised for a broad range\nof problems.",
        "positive": "Shape instabilities in vesicles: a phase-field model: A phase field model for dealing with shape instabilities in fluid membrane\nvesicles is presented. This model takes into account the Canham-Helfrich\nbending energy with spontaneous curvature. A dynamic equation for the\nphase-field is also derived. With this model it is possible to see the vesicle\nshape deformation dynamically, when some external agent instabilizes the\nmembrane, for instance, inducing an inhomogeneous spontaneous curvature. The\nnumerical scheme used is detailed and some stationary shapes are shown together\nwith a shape diagram for vesicles of spherical topology and no spontaneous\ncurvature, in agreement with known results."
    },
    {
        "anchor": "A graph theoretical analysis of the energy landscape of model polymers: In systems characterized by a rough potential energy landscape, local\nenergetic minima and saddles define a network of metastable states whose\ntopology strongly influences the dynamics. Changes in temperature, causing the\nmerging and splitting of metastable states, have non trivial effects on such\nnetworks and must be taken into account. We do this by means of a recently\nproposed renormalization procedure. This method is applied to analyze the\ntopology of the network of metastable states for different polypeptidic\nsequences in a minimalistic polymer model. A smaller spectral dimension emerges\nas a hallmark of stability of the global energy minimum and highlights a\nnon-obvious link between dynamic and thermodynamic properties.",
        "positive": "Evaluating the Laplace pressure of water nanodroplets from simulations: We calculate the components of the microscopic pressure tensor as a function\nof radial distance r from the centre of a spherical water droplet, modelled\nusing the TIP4P/2005 potential. To do so, we modify a coarse-graining method\nfor calculating the microscopic pressure [T. Ikeshoji, B. Hafskjold, and H.\nFuruholt, Mol. Simul. 29, 101 (2003)] in order to apply it to a rigid molecular\nmodel of water. As test cases, we study nanodroplets ranging in size from 776\nto 2880 molecules at 220 K. Beneath a surface region comprising approximately\ntwo molecular layers, the pressure tensor becomes approximately isotropic and\nconstant with r. We find that the dependence of the pressure on droplet radius\nis that expected from the Young-Laplace equation, despite the small size of the\ndroplets."
    },
    {
        "anchor": "Interactions between Silica Particles in the Presence of Multivalent\n  Coions: Forces between charged silica particles in solutions of multivalent coions\nare measured with colloidal probe technique based on atomic force microscopy.\nThe concentration of 1:z electrolytes is systematically varied to understand\nthe behavior of electrostatic interactions and double-layer properties in these\nsystems. Although the coions are multivalent the Derjaguin, Landau, Verwey, and\nOverbeek (DLVO) theory perfectly describes the measured force profiles. The\ndiffuse-layer potentials and regulation properties are extracted from the\nforces profiles by using the DLVO theory. The dependencies of the diffuse-layer\npotential and regulation parameter shift to lower concentration with increasing\ncoion valence when plotted as a function of concentration of 1:z salt.\nInterestingly, these profiles collapse to a master curve if plotted as a\nfunction of monovalent counterion concentration.",
        "positive": "A Force-Level Theory of the Rheology of Entangled Rod and Chain Polymer\n  Liquids. I. Tube Deformation, Microscopic Yielding and the Nonlinear Elastic\n  Limit: We employ a first principles, force-level approach to self-consistently\nconstruct the anharmonic tube confinement field for entangled fluids of rigid\nneedles and for primitive-path (PP) level chains in two limiting situations\nwhere chain stretching is assumed to either completely relax or remain\nunrelaxed. The influence of shear and extensional deformation and polymer\norientation is determined in a nonlinear elastic limit where dissipative\nrelaxation processes are intentionally neglected. For needles and PP-level\nchains, a Gaussian analysis of transverse polymer dynamical fluctuations\npredicts that deformation-induced orientation leads to tube dilation. In\ncontrast, for deformed polymers in which chain stretch does not relax we find\ntube compression. For all three systems, a finite maximum transverse\nentanglement force localizing the polymers in effective tubes is predicted. The\nconditions when this entanglement force can be overcome (a force imbalance) by\nan externally applied force associated with macroscopic deformation can be\ncrisply defined in the nonlinear elastic limit, and the possibility of a\n\"microscopic absolute yielding\" event destroying the tube confinement can be\nanalyzed. For needles and contour-relaxed PP chains, this force imbalance is\nfound to occur at a stress of order the equilibrium shear modulus and thus a\nstrain of order unity, corresponding to a mechanically fragile entanglement\ntube field. However, for unrelaxed stretched chains, tube compression\nstabilizes transverse polymer confinement, and there appears to be no force\nimbalance. These results collectively suggest that the crossover from elastic\nto irreversible viscous response requires chain retraction to initiate\ndisentanglement. We qualitatively discuss comparisons with existing\nphenomenological models for nonlinear startup shear, step strain, and creep\nrheology experiments."
    },
    {
        "anchor": "The standard mean-field treatment of inter-particle attraction in\n  classical DFT is better than one might expect: In classical density functional theory (DFT) the part of the Helmholtz free\nenergy functional arising from attractive inter-particle interactions is often\ntreated in a mean-field or van der Waals approximation. On the face of it, this\nis a somewhat crude treatment as the resulting functional generates the simple\nrandom phase approximation (RPA) for the bulk fluid pair direct correlation\nfunction. We explain why using standard mean-field DFT to describe\ninhomogeneous fluid structure and thermodynamics is more accurate than one\nmight expect based on this observation. By considering the pair correlation\nfunction $g(x)$ and structure factor $S(k)$ of a one-dimensional model fluid,\nfor which exact results are available, we show that the mean-field DFT,\nemployed within the test-particle procedure, yields results much superior to\nthose from the RPA closure of the bulk Ornstein-Zernike equation. We argue that\none should not judge the quality of a DFT based solely on the approximation it\ngenerates for the bulk pair direct correlation function.",
        "positive": "Driven transport of active particles through arrays of symmetric\n  obstacles: We numerically examine the driven transport of an overdamped self-propelled\nparticle through a two-dimensional array of circular obstacles. A detailed\nanalysis of transport quantifiers (mobility and diffusivity) has been performed\nfor two types of channels, {\\it channel I} and {\\it channel II}, that\nrespectively correspond to the parallel and diagonal drives with respect to the\narray axis. Our simulation results show that the signatures of pinning actions\nand depinning processes in the array of obstacles are manifested through excess\ndiffusion peaks or sudden drops in diffusivity, and abrupt jumps in mobility\nwith varying amplitude of the drive. The underlying depinning mechanisms and\nthe associated threshold driving strength largely depend on the persistent\nlength of self-propulsion. For low driving strength, both diffusivity and\nmobility are noticeably suppressed by the array of obstacles, irrespective of\nthe self-propulsion parameters and direction of the drive. When self-propulsion\nlength is larger than a channel compartment size, transport quantifiers are\ninsensitive to the rotational relaxation time. Transport with diagonal drives\nfeatures self-propulsion-dependent negative differential mobility. The\namplitude of the negative differential mobility of an active particle is much\nlarger than that of a passive one. The present analysis aims at understanding\nthe driven transport of active species like, bacteria, virus, Janus Particle\netc. in porous medium."
    },
    {
        "anchor": "Dynamics of particles with \"key-lock\" interactions: The dynamics of particles interacting by key-lock binding of attached\nbiomolecules are studied theoretically. Examples of such systems include\nDNA-functionalized colloids as well as nanoparticles grafted with antibodies to\ncell membrane proteins. Depending on the coverage of the functional groups, we\npredict two distinct regimes separated by a percolation transition. In the\nlocalized regime at low coverage, the system exhibits a broad, power law like\ndistribution of particle departure times. At higher coverage, there is an\ninterplay between departure dynamics and particle diffusion. This interplay\nleads to a sharp increase of the departure times, a phenomenon qualitatively\nsimilar to aging in glassy systems. This diffusive regime is analogous to\ndispersive transport in disordered semiconductors: depending on the interaction\nparameters, the diffusion behavior ranges from standard diffusion to anomalous,\nsubdiffusive behavior. The connection to recent experiments and implications\nfor future studies are discussed.",
        "positive": "A mesoscopic field theoretical approach for active systems: We introduce a mesocopic modeling approach for active systems. The continuum\nmodel allows to consider microscopic details as well as emerging macroscopic\nbehavior and can be considered as a minimal continuum model to describe generic\nproperties of active systems with isotropic agents. The model combines aspects\nfrom phase field crystal (PFC) models and Toner-Tu models. The results are\nvalidated by reproducing results obtained with corresponding agent-based\nmicroscopic models. We consider binary collisions, collective motion and vortex\nformation. For larger numbers of particles we analyze the coarsening process in\nactive crystals and identify giant number fluctuation in the cluster formation\nprocess."
    },
    {
        "anchor": "Short note: Transformation between different solution methods for\n  general axisymmetric tangential contact problems in Hertz-Mindlin\n  approximation: The transition between two conceptionally different solution procedures for\ngeneral axisymmetric tangential contact problems with arbitrary laoding\nhistories under Hertz-Mindlin assumptions is demonstrated, namely J\\\"ager's\nsuperposition solution and the method of dimensionality reduction. Both finite\nand ininite superpositions of Cattaneo-Mindlin basis functions are considered.\nIt is shown how the weights in the superposition solution can be easily\nobtained from the displacements in the MDR model.",
        "positive": "Elusive Unfoldability: Learning a Contact Potential to Fold Crambin: We investigate the extent to which the commonly used standard pairwise\ncontact potential can be used to identify the native fold of a protein. Ideally\none would hope that a universal energy function exists, for which the native\nfolds of all proteins are the respective ground states. Here we pose a much\nmore restricted question: is it possible to find a set of contact parameters\nfor which the energy of the native contact map of a single protein (crambin) is\nlower than that of all possible physically realizable decoy maps. We seek such\na set of parameters by perceptron learning, a procedure which is guaranteed to\nfind such a set if it exists. We found that it is extremely hard (and most\nprobably, impossible) to fine tune contact parameters that will assign all\nalternative conformations higher energy than that of the native map. This\nfinding clearly indicates that it is impossible to derive a general pairwise\ncontact potential that can be used to fold any given protein. Inclusion of\nadditional energy terms, such as hydrophobic (solvation), hydrogen bond or\nmulti-body interactions may help to attain foldability within specific\nstructural families."
    },
    {
        "anchor": "Transport of flexible chiral objects in a uniform shear flow: The transport of slightly deformable chiral objects in a uniform shear flow\nis investigated. Depending on the equilibrium configuration one finds up to\nfour different asymptotic states that can be distinguished by a lateral drift\nvelocity of their center of mass, a rotational motion about the center of mass\nand deformations of the object. These deformations influence the magnitudes of\nthe principal axes of the second moment tensor of the considered object and\nalso modify a scalar index characterizing its chirality. Moreover, the\ndeformations induced by the shear flow are essential for the phenomenon of\ndynamical symmetry breaking: Objects that are achiral under equilibrium\nconditions may dynamically acquire chirality and consequently experience a\ndrift in the lateral direction.",
        "positive": "Stability of a Vortex in Spinor Bose-Einstein Condensate: We propose a method to create a vortex in BEC utilizing the spin degree of\nfreedom. We consider the optical plug at the center of the vortex, which makes\nthe vortex-creation process stable. We also investigate the instability of the\nhalfway state to complete vortex state without the optical plug."
    },
    {
        "anchor": "Sculpting the Vertex: Manipulating the Configuration Space Topography\n  and Topology of Origami Vertices to Design Mechanical Robustness: The geometric, aesthetic, and mathematical elegance of origami is being\nrecognized as a powerful pathway to self-assembly of micro and nano-scale\nmachines with programmable mechanical properties. The typical approach to\ndesigning the mechanical response of an ideal origami machine is to include\nmechanisms where mechanical constraints transform applied forces into a desired\nmotion along a narrow set of degrees of freedom. In fact, to date, most design\napproaches focus on building up complex mechanisms from simple ones in ways\nthat preserve each individual mechanism's degree of freedom (DOF), with\nexamples ranging from simple robotic arms to homogenous arrays of identical\nvertices, such as the well-known Miura-ori. However, such approaches typically\nrequire tight fabrication tolerances, and often suffer from parasitic\ncompliance. In this work, we demonstrate a technique in which\nhigh-degree-of-freedom mechanisms associated with single vertices are\nheterogeneously combined so that the coupled phase spaces of neighboring\nvertices are pared down to a controlled range of motions. This approach has the\nadvantage that it produces mechanisms that retain the DOF at each vertex, are\nrobust against fabrication tolerances and parasitic compliance, but\nnevertheless effectively constrain the range of motion of the entire machine.\nWe demonstrate the utility of this approach by mapping out the configuration\nspace for the modified Miura-ori vertex of degree 6, and show that when strung\ntogether, their combined configuration spaces create mechanisms that isolate\ndeformations, constrain the configuration topology of neighboring vertices, or\nlead to sequential bistable folding throughout the entire origami sheet.",
        "positive": "A Comprehensive and Versatile Multimodal Deep Learning Approach for\n  Predicting Diverse Properties of Advanced Materials: We present a multimodal deep learning (MDL) framework for predicting physical\nproperties of a 10-dimensional acrylic polymer composite material by merging\nphysical attributes and chemical data. Our MDL model comprises four modules,\nincluding three generative deep learning models for material structure\ncharacterization and a fourth model for property prediction. Our approach\nhandles an 18-dimensional complexity, with 10 compositional inputs and 8\nproperty outputs, successfully predicting 913,680 property data points across\n114,210 composition conditions. This level of complexity is unprecedented in\ncomputational materials science, particularly for materials with undefined\nstructures. We propose a framework to analyze the high-dimensional information\nspace for inverse material design, demonstrating flexibility and adaptability\nto various materials and scales, provided sufficient data is available. This\nstudy advances future research on different materials and the development of\nmore sophisticated models, drawing us closer to the ultimate goal of predicting\nall properties of all materials."
    },
    {
        "anchor": "Lattices of hydrodynamically interacting flapping swimmers: Fish schools and bird flocks exhibit complex collective dynamics whose\nself-organization principles are largely unknown. The influence of\nhydrodynamics on such collectives has been relatively unexplored theoretically,\nin part due to the difficulty in modeling the temporally long-lived\nhydrodynamic interactions between many dynamic bodies. We address this through\na novel discrete-time dynamical system (iterated map) that describes the\nhydrodynamic interactions between flapping swimmers arranged in one- and\ntwo-dimensional lattice formations. Our 1D results exhibit good agreement with\npreviously published experimental data, in particular predicting the\nbistability of schooling states and new instabilities that can be probed in\nexperimental settings. For 2D lattices, we determine the formations for which\nswimmers optimally benefit from hydrodynamic interactions. We thus obtain the\nfollowing hierarchy: while a side-by-side single-row \"phalanx\" formation offers\na small improvement over a solitary swimmer, 1D in-line and 2D rectangular\nlattice formations exhibit substantial improvements, with the 2D diamond\nlattice offering the largest hydrodynamic benefit. Generally, our\nself-consistent modeling framework may be broadly applicable to active systems\nin which the collective dynamics is primarily driven by a fluid-mediated\nmemory.",
        "positive": "Mechanical Properties of Warped Membranes: We explore how a frozen background metric affects the mechanical properties\nof planar membranes with a shear modulus. We focus on a special class of\n\"warped membranes\" with a preferred random height profile characterized by\nrandom Gaussian variables $h({\\bf q})$ in Fourier space with zero mean and\nvariance $<|h({\\bf q})|^2> \\sim q^{-d_h}$ and show that in the linear response\nregime the mechanical properties depend dramatically on the system size $L$ for\n$d_h \\ge 2$. Membranes with $d_h=4$ could be produced by flash polymerization\nof lyotropic smectic liquid crystals. Via a self consistent screening\napproximation we find that the renormalized bending rigidity increases as\n$\\kappa_R \\sim L^{(d_h-2)/2}$ for membranes of size $L$, while the Young and\nshear modulii decrease according to $Y_R,\\ \\mu_R \\sim L^{-(d_h-2)/2}$ resulting\nin a universal Poisson ratio. Numerical results show good agreement with\nanalytically determined exponents."
    },
    {
        "anchor": "Emergence of a Barchan Belt in a Unidirectional Flow: Experiment and\n  Numerical Simulation: We observed time evolution of dune fields in a water tank experiment and\nsimulated it by using a simple model without taking complex fluid dynamics into\naccount. The initial sand bed changed its form into transverse ripples, that\nis, dunes with straight crest lines perpendicular to the flow direction. Then\nthe crescentic shaped dunes called barchans emerged from transverse ripples.",
        "positive": "Compression-induced stiffness in the buckling of a one fiber composite: We study the buckling of a one fiber composite whose matrix stiffness is\nslightly dependent on the compressive force. We show that the equilibrium\ncurves of the system exhibit a limit load when the induced stiffness parameter\ngets bigger than a threshold. This limit load increases when increasing the\nstiffness parameter and is related to a possible localized path in the\npost-buckling domain. Such a change in the maximum load may be very desirable\nfrom a structural stand point."
    },
    {
        "anchor": "A series representation of the nonlinear equation for axisymmetrical\n  fluid membrane shape: Whatever the fluid lipid vesicle is modeled as the spontaneous-curvature,\nbilayer-coupling, or the area-difference elasticity, and no matter whether a\npulling axial force applied at the vesicle poles or not, a universal shape\nequation presents when the shape has both axisymmetry and up-down symmetry.\nThis equation is a second order nonlinear ordinary differential equation about\nthe sine $sin\\psi (r)$ of the angle $\\psi (r)$ between the tangent of the\ncontour and the radial axis $r$. However, analytically there is not a generally\napplicable method to solve it, while numerically the angle $\\psi (0)$ can not\nbe obtained unless by tricky extrapolation for $r=0$ is a singular point of the\nequation. We report an infinite series representation of the equation, in which\nthe known solutions are some special cases, and a new family of shapes related\nto the membrane microtubule formation, in which $sin\\psi (0)$ takes values from\n0 to $\\pi /2$, is given.",
        "positive": "Molecular dynamics simulations of active entangled polymers reptating\n  through a passive mesh: In this work, we explore the dynamics of active entangled chains using\nmolecular dynamics simulations of a modified Kremer-Grest model. The active\nchains are diluted in a mesh of very long passive linear chains, to avoid\nconstraint release effects, and an active force is applied to the monomers in a\nway that it imparts a constant polar drift velocity along the primitive path.\nThe simulation results show that, over a wide range of activity values, the\nconformational properties of the chains and the tubes are not affected, but the\ndynamics of the chains are severely modified. Despite not having an explicit\ntube, the simulations verify all the predictions of the theory about all\npossible observables very accurately, including a diffusion coefficient that\nbecomes independent of the molecular weight at moderate values of the activity.\nOverall, this work provides novel information on the study of active entangled\npolymers, giving a route map for studying this phenomenon and an efficient way\nof obtaining a polar activity that reproduces the physics of the active\nreptation theory."
    },
    {
        "anchor": "Landau-Levich Enhanced Cheerios Effect: We study the capillary attraction force between two fibers dynamically\nwithdrawn from a bath. We propose an experimental method to measure this force\nand show that its magnitude strongly increases with the retraction speed by up\nto a factor ten compared to the static case. We show that this remarkable\nincrease stems from the shape of the dynamical meniscus between the two fibers.\nWe first study the dynamical meniscus around one fiber, and obtain experimental\nand numerical scaling of its size increase with the capillary number, which is\nnot captured by the classical Landau-Levich-Derjaguin theory. We then show that\nthe shape of the deformed air-liquid interface around two fibers can be\ninferred from the linear superposition of the interface around a single fiber.\nThese results yield an analytical expression for the attraction which compares\nwell with the experimental data. Our study reveals the critical role of the\nretraction speed to create stronger capillary interactions, with potential\napplications in industry or biology.",
        "positive": "Current rectification, switching, polarons, and defects in molecular\n  electronic devices: Devices for nano- and molecular size electronics are currently a focus of\nresearch aimed at an efficient current rectification and switching. A few\ngeneric molecular scale devices are reviewed here on the basis of\nfirst-principles and model approaches. Current rectification by (ballistic)\nmolecular quantum dots can produce the rectification ratio ~100. Current\nswitching due to conformational changes in the molecules is slow, on the order\nof a few kHz. Fast switching (~1THz) may be achieved, at least in principle, in\na degenerate molecular quantum dot with strong coupling of electrons with\nvibrational excitations. We show that the mean-field approach fails to properly\ndescribe intrinsic molecular switching and present an exact solution to the\nproblem. Defects in molecular films result in spurious peaks in conductance,\napparent negative differential resistance, and may also lead to unusual\ntemperature and bias dependence of current. The observed switching in many\ncases is_extrinsic_, caused by changes in molecule-electrode geometry, molecule\nreconfiguration, metallic filament formation through, and/or changing amount of\ndisorder in a molecular film. We give experimental examples of telegraph\n\"switching\" and \"hot spot\" formation in the molecular films."
    },
    {
        "anchor": "Waves, Algebraic Growth and Clumping in Sedimenting Disk Arrays: An array of spheres descending slowly through a viscous fluid always clumps\n[J.M. Crowley, J. Fluid Mech. {\\bf 45}, 151 (1971)]. We show that anisotropic\nparticle shape qualitatively transforms this iconic instability of collective\nsedimentation. In experiment and theory on disks, aligned facing their\nneighbours in a horizontal one-dimensional lattice and settling at Reynolds\nnumber $\\sim 10^{-4}$ in a quasi-two-dimensional slab geometry, we find that\nfor large enough lattice spacing the coupling of disk orientation and\ntranslation rescues the array from the clumping instability. Despite the\nabsence of inertia the resulting dynamics displays the wavelike excitations of\na mass-and-spring array, with a conserved \"momentum\" in the form of the\ncollective tilt of the disks and an emergent spring stiffness from the viscous\nhydrodynamic interaction. However, the non-normal character of the dynamical\nmatrix leads to algebraic growth of perturbations even in the linearly stable\nregime. Stability analysis demarcates a phase boundary in the plane of\nwavenumber and lattice spacing, separating the regimes of algebraically growing\nwaves and clumping, in quantitative agreement with our experiments. Anisotropic\nshape thus suppresses the classic linear instability of sedimenting sphere\narrays, introduces a new conserved variable, and opens a window to the physics\nof transient growth of linearly stable modes.",
        "positive": "Study of the Liquid/Vapor Interfacial Properties of Concentrated\n  Polyelectrolyte-Surfactant Mixtures Using Surface Tensiometry and Neutron\n  Reflectometry: Equilibrium, Adsorption Kinetics and Dilational Rheology: The adsorption of mixtures of poly(diallyldimethylammonium chloride)\n(PDADMAC) and sodium N-lauroyl-N-methyltaurate (SLMT) at the water / vapor\ninterface has been studied using drop profile tensiometry and neutron\nreflectometry. This study sheds light on the mechanisms involved in the\nadsorption of polyelectrolyte-oppositely charged surfactants by the\ncharacterization of both equilibrium and dynamics features associated with the\nlayer formation at the fluid interface. The results are discussed in terms of\nan adsorption-equilibration of the interfacial layers as a two-step process:\nthe initial stages involve the adsorption of polyelectrolyte-surfactant\ncomplexes formed in the bulk, and a subsequent stage involves reorganization of\nthe interface. This work contributes to the understanding of the\nphysico-chemical features of systems that undergo complex bulk and interfacial\ninteractions with importance in science and technology."
    },
    {
        "anchor": "Universal Fast Mode and Potential-dependent Regimes in Wetting Kinetics: We present simulation results from a comprehensive molecular dynamics (MD)\nstudy of surface-directed spinodal decomposition (SDSD) in unstable symmetric\nbinary mixtures at wetting surfaces. We consider long-ranged and short-ranged\nsurface fields to investigate the early-stage wetting kinetics. The attractive\npart of the long-ranged potential is of the form $V(z) \\sim z^{-n}$, where $z$\nis the distance from the surface and $n$ is the power-law exponent. We find\nthat the wetting-layer thickness $R_1(t)$ at very early times exhibits a\npower-law growth with an exponent $\\alpha = 1/(n+2)$. It then crosses over to a\nuniversal fast-mode regime with $\\alpha=3/2$. In contrast, for the short-ranged\nsurface potential, a logarithmic behavior in $R_1(t)$ is observed at initial\ntimes. Remarkably, similar rapid growth is seen in this case too. We provide\nphenomenological arguments to understand these growth laws. Our MD results\nfirmly establish the existence of universal fast-mode kinetics and settle the\nrelated controversy.",
        "positive": "Self-sustained oscillations of active viscoelastic matter: Models of active nematics in biological systems normally require complexity\narising from the hydrodynamics involved at the microscopic level as well as the\nviscoelastic nature of the system. Here we show that a minimal,\nspace-independent, model based on the temporal alignment of active and\npolymeric particles provides an avenue to predict and study their coupled\ndynamics within the framework of dynamical systems. In particular, we examine,\nusing analytical and numerical methods, how such a simple model can display\nself-sustained oscillations in an activity-driven viscoelastic shear flow."
    },
    {
        "anchor": "The Meniscus on the Outside of a Circular Cylinder: from Microscopic to\n  Macroscopic Scales: We systematically study the meniscus on the outside of a small circular\ncylinder vertically immersed in a liquid bath in a cylindrical container that\nis coaxial with the cylinder. The cylinder has a radius $R$ much smaller than\nthe capillary length, $\\kappa^{-1}$, and the container radius, $L$, is varied\nfrom a small value comparable to $R$ to $\\infty$. In the limit of $L \\ll\n\\kappa^{-1}$, we analytically solve the general Young-Laplace equation\ngoverning the meniscus profile and show that the meniscus height, $\\Delta h$,\nscales approximately with $R\\ln (L/R)$. In the opposite limit where $L \\gg\n\\kappa^{-1}$, $\\Delta h$ becomes independent of $L$ and scales with $R\\ln\n(\\kappa^{-1}/R)$. We implement a numerical scheme to solve the general\nYoung-Laplace equation for an arbitrary $L$ and demonstrate the crossover of\nthe meniscus profile between these two limits. The crossover region has been\ndetermined to be roughly $0.4\\kappa^{-1} \\lesssim L \\lesssim 4\\kappa^{-1}$. An\napproximate analytical expression has been found for $\\Delta h$, enabling its\naccurate prediction at any values of $L$ that ranges from microscopic to\nmacroscopic scales.",
        "positive": "Nonlinear screening and gas-liquid separation in suspensions of charged\n  colloids: We calculate phase diagrams of charged colloidal spheres (valency $Z$ and\nradius $a$) in a 1:1 electrolyte from multi-centered nonlinear\nPoisson-Boltzmann theory. Our theory takes into account charge-renormalization\nof the colloidal interactions and volume terms due to many-body effects. For\nvalencies as small as Z=1 and as large as $10^4$ we find a gas--liquid spinodal\ninstability in the colloid-salt phase diagram provided $Z\\lB/a\\gtrsim24\\pm1$,\nwhere $\\lB$ is the Bjerrum length."
    },
    {
        "anchor": "Comment on \"Explicit Analytical Solution for Random Close Packing in\n  $d=2$ and $d=3$\": In this short commentary we provide our comment on the article \"Explicit\nAnalytical Solution for Random Close Packing in $d=2$ and $d=3$\" and its\nsubsequent Erratum that are recently published in Physical Review Letters. In\nthat Letter, the author presented an explicit analytical derivation of the\nvolume fractions $\\phi_{\\rm RCP}$ for random close packings (RCP) in both $d=2$\nand $d=3$. Here we first briefly show the key parts of the derivation in\nRef.~\\cite{Za22}, and then provide arguments on why we think the derivation of\nthe analytical results is problematic and unjustified, and why the Erratum does\nnot address or clarify the concerns raised previously by us.",
        "positive": "Phase Behavior and Emulsion Stability of the Aot/Decane/ Water/NaCl\n  System at Very Low Volume Fractions of Oil: The stability of a ternary system composed of decane/water/Aerosol-OT and\nsalt is revisited. Phase diagrams and emulsions similar in composition to those\npreviously studied by Hofman and Stein [Hofman, 1991] were made. Ac- cording to\nour results, and contrary to the common experience, these systems exhibit a\nmaximum of stability very close to the balance zone."
    },
    {
        "anchor": "Bound states of interacting helium atoms: We study the possibility of existence of bound states for two interacting\nHe-4 atoms. It is shown that for some potentials, there exist not only discrete\nlevels but also bands akin to those in the Kronig--Penney model.",
        "positive": "Three-step melting of hard superdisks in two dimensions: We explore the link between the melting scenarios of two-dimensional systems\nof hard disks and squares through replica-exchange Monte Carlo simulations of\nhard superdisks. The well-known melting scenarios are observed in the disk and\nsquare limits, while we observe an unusual three-step scenario for dual-shapes.\nWe find that two mesophases mediate the melting: a hexatic phase and another\nfluid phase with a $D_2$ local symmetry, we call it rhombatic, where both bond\nand particle orientational orders are quasi-long-range. Our results show that\nnot only can the melting process of liquid-crystal forming molecules be\ncomplicated, where elongated shapes stabilize several mesophases, but also that\nof anisotropic quasispherical molecules."
    },
    {
        "anchor": "Phase diagrams of confined square lattice links: We study by Monte Carlo simulations and scaling analysis two models of pairs\nof confined and dense ring polymers in two dimensions. The pair of ring\npolymers are modelled by squared lattice polygons confined within a square\ncavity and they are placed in relation to each other to be either unlinked or\nlinked in the plane. The observed rich phase diagrams of the two models reveal\nseveral equilibrium phases separated by first order and continuous phase\nboundaries whose critical nature depend on this reciprocal placements. We\nestimate numerically the critical exponents associated with the phase\nboundaries and with the multicritical points where first order and continuous\nphase boundaries meet.",
        "positive": "Drop tower setup for dynamic light scattering in dense gas-fluidized\n  granular media: Investigation of dynamics in dense granular media is challenging. Here we\npresent a setup that facilitates gas fluidization of dense granular media in\nmicrogravity. The dynamics is characterized using diffusing wave spectroscopy.\nWe demonstrate that agitated granular media reach a steady state within\nfractions of a second in drop tower flights. The intensity autocorrelation\nfunctions obtained in microgravity show a remarkable dependence on sample\nvolume fraction and driving strength. A plateau in correlation merges at low\nvolume fractions and strong driving, while correlation decays only very slowly\nbut continuously at high packing fractions. The setup allows to independently\nset sample volume fraction and driving strength, and thus extends the\npossibilities for investigations on dynamics in dense granular on ground."
    },
    {
        "anchor": "Drag induced lift in granular media: Laboratory experiments and numerical simulation reveal that a submerged\nintruder dragged horizontally at constant velocity within a granular medium\nexperiences a lift force whose sign and magnitude depend on the intruder shape.\nComparing the stress on a flat plate at varied inclination angle with the local\nsurface stress on the intruders at regions with the same orientation\ndemonstrates that intruder lift forces are well approximated as the sum of\ncontributions from flat-plate elements. The plate stress is deduced from the\nforce balance on the flowing media near the plate.",
        "positive": "Phase diagram for morphological transitions of wetting films on\n  chemically structured substrates: Using an interface displacement model we calculate the shapes of thin\nliquidlike films adsorbed on flat substrates containing a chemical stripe. We\ndetermine the entire phase diagram of morphological phase transitions in these\nfilms as function of temperature, undersaturation, and stripe width"
    },
    {
        "anchor": "Topological defect launches 3D mound in the active nematic sheet of\n  neural progenitors: Cultured stem cells have become a standard platform not only for regenerative\nmedicine and developmental biology but also for biophysical studies. Yet, the\ncharacterization of cultured stem cells at the level of morphology and\nmacroscopic patterns resulting from cell-to-cell interactions remain largely\nqualitative, even though they are the simplest features observed in everyday\nexperiments. Here we report that neural progenitor cells (NPCs), which are\nmultipotent stem cells that give rise to cells in the central nervous system,\nrapidly glide and stochastically reverse its velocity while locally aligning\nwith neighboring cells, thus showing features of an active nematic system.\nWithin the two-dimensional nematic pattern, we find interspaced topological\ndefects with +1/2 and -1/2 charges. Remarkably, we identified rapid cell\naccumulation leading to three-dimensional mounds at the +1/2 topological\ndefects. Single-cell level imaging around the defects allowed quantification of\nthe evolving cell density, clarifying that not only cells concentrate at +1/2\ndefects, but also escape from -1/2 defects. We propose the mechanism of\ninstability around the defects as the interplay between the anisotropic\nfriction and the active force field, thus addressing a novel universal\nmechanism for local cell density control.",
        "positive": "Finite-Difference Lattice Boltzmann Methods for binary fluids: We investigate two-fluid BGK kinetic methods for binary fluids. The developed\ntheory works for asymmetric as well as symmetric systems. For symmetric systems\nit recovers Sirovich's theory and is summarized in models A and B. For\nasymmetric systems it contributes models C, D and E which are especially useful\nwhen the total masses and/or local temperatures of the two components are\ngreatly different. The kinetic models are discretized based on an octagonal\ndiscrete velocity model. The discrete-velocity kinetic models and the\ncontinuous ones are required to describe the same hydrodynamic equations. The\ncombination of a discrete-velocity kinetic model and an appropriate\nfinite-difference scheme composes a finite-difference lattice Boltzmann method.\nThe validity of the formulated methods is verified by investigating (i) uniform\nrelaxation processes, (ii) isothermal Couette flow, and (iii) diffusion\nbehavior."
    },
    {
        "anchor": "Geometric percolation of colloids in shear flow: We combine a heuristic theory of geometric percolation and the Smoluchowski\ntheory of colloid dynamics to predict the impact of shear flow on the\npercolation threshold of hard spherical colloidal particles, and verify our\nfindings by means of molecular dynamics simulations. It appears that the impact\nof shear flow is subtle and highly non-trivial, even in the absence of\nhydrodynamic interactions between the particles. The presence of shear flow can\nboth increase and decrease the percolation threshold, depending on the\ncriterion used for determining whether or not two particles are connected and\non the P\\'{e}clet number. Our approach opens up a route to quantitatively\npredict the percolation threshold in nanocomposite materials that, as a rule,\nare produced under non-equilibrium conditions, making comparison with\nequilibrium percolation theory tenuous. Our theory can be adapted\nstraightforwardly for application in other types of flow field, and particles\nof different shape or interacting via other than hard-core potentials.",
        "positive": "Is directed percolation in colloid-polymer mixtures linked to dynamic\n  arrest?: Using computer simulations, we study the dynamic arrest in a schematic model\nof colloid-polymer mixtures combining short-ranged attractions with long-ranged\nrepulsions. The arrested gel is a dilute rigid network of colloidal particles\nbonded due to the strong attractions. Without repulsions, the gel forms at the\nspinodal through arrested phase separation. In the ergodic suspension at\nsufficiently high densities, colloidal clusters form temporary networks that\npercolate space. Recently [Nat. Commun. 7, 11817 (2016)], it has been proposed\nthat the transition of these networks to directed percolation coincides with\nthe onset of the dynamic arrest, thus linking structure to dynamics. Here, we\nevaluate for various screening lengths the underlying gas-liquid binodal and\nthe percolation transitions. We find that directed percolation shifts the\ncontinuous percolation line to larger densities, but even beyond this line the\nsuspension remains ergodic. Only when approaching the spinodal does dynamic\narrest occur. Competing repulsions thus do not modify the qualitative scenario\nfor non-equilibrium gelation, although the structure of the emerging\npercolating network shows some differences."
    },
    {
        "anchor": "Capillary and winding transitions in a confined cholesteric liquid\n  crystal: We consider a Lebwohl-Lasher model of chiral particles confined in a planar\ncell (slit pore) with different boundary conditions, and solve it using\nmean-field theory. The phase behaviour of the system with respect to\ntemperature and pore width is studied. Two phenomena are observed: (i) an\nisotropic-cholesteric transition which exhibits an oscillatory structure with\nrespect to pore width, and (ii) an infinite set of winding transitions caused\nby commensuration effects between cholesteric pitch and pore width. The latter\ntransitions have been predicted and analysed by other authors for cholesterics\nconfined in a fixed pore and subject to an external field promoting the\nuniaxial nematic phase; here we induce winding transitions solely from geometry\nby changing the pore width at zero external field (a setup recently explored in\nAtomic-Force Microscopy experiments). In contrast with previous studies, we\nobtain the phase diagrams in the temperature vs pore width plane, including the\nisotropic-cholesteric transition, the winding transitions and their complex\nrelationship. In particular, the structure of winding transitions terminates at\nthe capillary isotropic-cholesteric transition via triple points where the\nconfined isotropic phase coexists with two cholesterics with different helix\nindices. For symmetric and asymmetric monostable plate anchorings the phase\ndiagram are qualitatively similar.",
        "positive": "High accuracy Monte Carlo study of dispersion model of biaxial liquid\n  crystals: We present a high accuracy Monte Carlo simulation study of the Isotropic -\nNematic phase transition of a lattice dispersion model of biaxial liquid\ncrystals. The NI coexistence curve terminating at the Landau critical point\nhave been determined using multiple histogram reweighting technique. A close\ninvestigation reveals a sharp departure in the nature of the $N$-$I$\ncoexistence curve in temperature- biaxiality parameter phase diagram in\ncomparison to the earlier theoretical (either mean-field or computer\nsimulation) predictions.The coexitence curve shows a change in curvature with\nincreasing value of the degree molecular biaxiality."
    },
    {
        "anchor": "Discrete fluidization of dense monodisperse emulsions in neutral wetting\n  microchannels: The rheology of pressure-driven flows of two-dimensional dense monodisperse\nemulsions in neutral wetting microchannels is investigated by means of\nmesoscopic lattice simulations, capable of handling large collections of\ndroplets, in the order of several hundreds. The simulations reveal that the\nfluidization of the emulsion proceeds through a sequence of discrete steps,\ncharacterized by yielding events whereby layers of droplets start rolling over\neach other, thus leading to sudden drops of the relative effective viscosity.\nIt is shown that such discrete fluidization is robust against loss of\nconfinement, namely it persists also in the regime of small ratios of the\ndroplet diameter over the microchannel width. We also develop a simple\nphenomenological model which predicts a linear relation between the relative\neffective viscosity of the emulsion and the product of the confinement\nparameter (global size of the device over droplet radius) and the viscosity\nratio between the disperse and continuous phases. The model shows excellent\nagreement with the numerical simulations. The present work offers new insights\nto enable the design of microfluidic scaffolds for tissue engineering\napplications and paves the way to detailed rheological studies of soft-glassy\nmaterials in complex geometries.",
        "positive": "Filter-feeding, near-field flows, and the morphologies of colonial\n  choanoflagellates: Efficient uptake of nutrients from the environment is an important component\nin the fitness of all microorganisms, and its dependence on size may reveal\nclues to the origins of evolutionary transitions to multicellularity. Because\npotential benefits in uptake rates must be viewed in the context of other costs\nand benefits of size, such as varying predation rates and the increased\nmetabolic costs associated with larger and more complex body plans, the uptake\nrate itself is not necessarily that which is optimized by evolution. Uptake\nrates can be strongly dependent on local organism geometry and its swimming\nspeed, providing selective pressure for particular arrangements. Here we\nexamine these issues for choanoflagellates, filter-feeding microorganisms that\nare the closest relatives of the animals. We explore the different\nmorphological variations of the choanoflagellete $Salpingoeca~rosetta$, which\ncan exist as a swimming cell, a sessile thecate cell, and as colonies of cells\nin various shapes. In the absence of other requirements and in a homogeneously\nnutritious environment, we find that the optimal strategy to maximize filter\nfeeding by the collar of microvilli is to swim fast, which favours swimming\nunicells. In large external flows, the sessile thecate cell becomes\nadvantageous. Effects of prey diffusion are discussed and also found to be to\nthe advantage of the swimming unicell."
    },
    {
        "anchor": "Formation and transportation of sand-heap in an inclined and vertically\n  vibrated container: We report the experimental findings of formation and motion of heap in\ngranular materials in an inclined and vertically vibrated container. We show\nexperimentally how the transport velocity of heap up container is related to\nthe driving acceleration as well as the driving frequency of exciter. An\nanalogous experiment was performed with a heap-shaped Plexiglas block. We\npropose that cohesion force resulted from pressure gradient in ambient gas\nplays a crucial role in enhancing and maintaining a heap, and ratchet effect\ncauses the movement of the heap. An equation which governs the transport\nvelocity of the heap is presented.",
        "positive": "Micron-sized atom traps made from magneto-optical thin films: We have produced magnetic patterns suitable for trapping and manipulating\nneutral atoms on a $1 \\mu$m length scale. The required patterns are made in\nCo/Pt thin films on a silicon substrate, using the heat from a focussed laser\nbeam to induce controlled domain reversal. In this way we draw lines and\n\"paint\" shaped areas of reversed magnetization with sub-micron resolution.\nThese structures produce magnetic microtraps above the surface that are\nsuitable for holding rubidium atoms with trap frequencies as high as ~1 MHz."
    },
    {
        "anchor": "Propagation of a Thermo-mechanical Perturbation on a Lipid Membrane: The propagation of sound waves on lipid monolayers supported on water has\nbeen studied during the melting transition. Since changes in volume, area, and\ncompressibility in lipid membranes have biological relevance, the observed\nsound propagation is of paramount importance. However, it is unknown what would\noccur on a lipid bilayer, which is a more approximate model of a cell membrane.\nWith the aim to answer this relevant question, we built an experimental setup\nto assemble long artificial lipid membranes. We found that if these membranes\nare heated in order to force local melting, a thermo-mechanical perturbation\npropagates a long distance. Our findings may support the existence of solitary\nwaves, postulated to explain the propagation of isentropic signals together\nwith the action potential in neurons.",
        "positive": "On phases in weakly interacting finite Bose systems: We study precursors of thermal phase transitions in finite systems of\ninteracting Bose gases. For weakly repulsive interactions there is a phase\ntransition to the one-vortex state. The distribution of zeros of the partition\nfunction indicates that this transition is first order, and the precursors of\nthe phase transition are already displayed in systems of a few dozen bosons.\nSystems of this size do not exhibit new phases as more vortices are added to\nthe system."
    },
    {
        "anchor": "Sieving and clogging in PEG-PEGDA hydrogel membranes: Hydrogels are promising systems for separation applications due to their\nstructural characteristics (i.e. hydrophilicity and porosity). In our study, we\ninvestigate the permeation of suspensions of rigid latex particles of different\nsizes through free-standing hydrogel membranes prepared by photopolymerization\nof a mixture of poly (ethylene glycol) diacrylate (PEGDA) and large poly\n(ethylene glycol) (PEG) chains of 300 000 g.mol-1 in the presence of a\nphotoinitiator. Atomic force microscopy (AFM) and cryoscanning electron\nmicroscopy (cryoSEM) were employed to characterize the structure of the\nhydrogel membranes. We find that the 20 nm particle permeation depends on both\nthe PEGDA/PEG composition and the pressure applied during filtration. In\ncontrast, we do not measure a significant permeation of the 100 nm and 1 $\\mu$m\nparticles, despite the presence of large cavities of 1 $\\mu$m evidenced by\ncryoSEM images. We suggest that the PEG chains induce local nanoscale defects\nin the cross-linking of PEGDA-rich walls separating the micron size cavities,\nthat control the permeation of particles and water. Moreover, we discuss the\ndecline of the permeation flux observed in the presence of latex particles,\ncompared to that of pure water. We suggest that a thin layer of particles forms\non the surface of the hydrogels.",
        "positive": "Effective interactions between a pair of nanoparticles: We investigate the effective interactions between two nanoparticles (or\ncolloids) immersed in a solvent exhibiting two-phase separation. Using a\nnon-local density functional theory, we determine the dependence of the\neffective potential on the separation of the nanoparticles when the solvent is\nnear bulk two-phase coexistence. If identical nanoparticles preferentially\nadsorbing phase $\\alpha$ are inserted into phase $\\beta$, thick wetting layers\nof the preferable phase $\\alpha$ develop at their surfaces. At some particular\nseparation $h_b$ of the nanoparticles, the wetting layers connect to form a\nsingle bridge, and the induced effective potential becomes strongly attractive\nfor all distances $h<h_b$. The bridging is a first order capillary condensation\nlike transition for all radii of the nanoparticles greater than the critical\nradius $R_c$, the value of which was estimated to be approximately\n$R_c\\approx20\\sigma$ for a temperature $T/T_c\\approx0.9$, where $\\sigma$ is the\nsize of the solvent (square-well) particles. For radii $R<R_c$ the process of\nbridging is continuous. If the same particles are inserted into the preferable\nphase $\\alpha$, the only effective interaction between them is induced by the\nshort-ranged depletion potential. If the nanoparticles have opposite adsorption\npreferences, only a single wetting layer forms around one of the nanoparticles\nand the effective interaction is strongly repulsive in both phases. The\nrepulsion, induced by a disruption of the wetting film by the presence of the\nsecond particle, is larger and slightly longer-ranged in a low density state."
    },
    {
        "anchor": "Observation of Spontaneous Helielectric Nematic Fluids: Electric Analogy\n  to Helimagnets: About a century ago, Born proposed a possible matter of state, ferroelectric\nfluid, might exist if the dipole moment is strong enough. The experimental\nrealisation of such states needs magnifying molecular polar nature to\nmacroscopic scales in liquids. Here, we report on the discovery of a novel\nchiral liquid matter state, dubbed chiral ferronematic, stabilized by the local\nferroelectric ordering coupled to the chiral helicity. It carries the polar\nvector rotating helically, corresponding to a helieletric structure, analogous\nto the magnetic counterpart of helimagnet. The state can be retained down to\nroom-temperature and demonstrates gigantic dielectric and nonlinear optical\nresponses. The novel matter state opens a new chapter for exploring the\nmaterial space of the diverse ferroelectric liquids.",
        "positive": "A potential inversion study of liquid CuBr: Hard electromagnetic radiation diffraction experiments on copper(I)-bromide\nmelt are presented. Combining the result of this experiment with earlier\nneutron diffraction experiments the partial pair distribution functions of CuBr\nhave been determined. The differing results for two of these functions obtained\nrecently by various techniques are discussed. A potential inversion scheme has\nbeen applied to generate three dimensional structures from the partial pair\ndistribution function. The angular correlations between near neighbor atoms\nhave been determined. These show characteristic differences with the\nglass-forming ZnCl2 melt. While in ZnCl2 melt the angle joining adjacent ZnCl4\ntetrahedra has been found - as in silica glass - well defined and the +-+\n(ZnClZn) angle distribution peaked the corresponding distribution function in\nCuBr is broad. This is probably a key to understand, why ZnCl2 but not CuBr\nmelt can be easily supercooled into a glassy state."
    },
    {
        "anchor": "Membrane tubule formation by banana-shaped proteins with or without\n  transient network structure: In living cells, membrane morphology is regulated by various proteins. Many\nmembrane reshaping proteins contain a Bin/Amphiphysin/Rvs (BAR) domain, which\nconsists of a banana-shaped rod. The BAR domain bends the biomembrane along the\nrod axis and the features of this anisotropic bending have recently been\nstudied. Here, we report on the role of the BAR protein rods in inducing\nmembrane tubulation, using large-scale coarse-grained simulations. We reveal\nthat a small spontaneous side curvature perpendicular to the rod can\ndrastically alter the tubulation dynamics at high protein density, whereas no\nsignificant difference is obtained at low density. A percolated network is\nintermediately formed depending on the side curvature. This network suppresses\ntubule protrusion, leading to the slow formation of fewer tubules. Thus, the\nside curvature, which is generated by protein--protein and membrane--protein\ninteractions, plays a significant role in tubulation dynamics. We also find\nthat positive surface tensions and the vesicle membrane curvature can stabilize\nthis network structure by suppressing the tubulation.",
        "positive": "Smart Polymeric Recognition of a Hexagonal Monolayer: We investigate the adsorption of a flexible polymer at a hexagonally\npatterned monolayer. All conformational polymer phases are identified, which\nenables the construction of a hyperphase diagram, parameterized by temperature\nand monolayer adsorption strength. The energy scale associated with the\nadsorption strength is a material parameter of the hybrid system that\ngenerically accommodates the behavior of entire classes of polymers interacting\nwith hexagonal substrates. We also discuss a bridge-building mechanism for the\nformation of unique layered polymer structures with potential for applications\nin nanoscale transport. High-quality data sets necessary for the statistical\nanalysis of the structural phase behavior of the system were obtained in\nextensive generalized-ensemble Monte Carlo computer simulations."
    },
    {
        "anchor": "Elastic property of single double-stranded DNA molecules: Theoretical\n  study and comparison with experiments: This paper aims at a comprehensive understanding on the novel elastic\nproperty of double-stranded DNA (dsDNA) discovered very recently through\nsingle-molecule manipulation techniques. A general elastic model for\ndouble-stranded biopolymers is proposed and a new structural parameter called\nthe folding angle $\\phi$ is introduced to characterize their deformations. The\nmechanical property of long dsDNA molecules is then studied based on this\nmodel, where the base-stacking interactions between DNA adjacent nucleotide\nbasepairs, the steric effects of basepairs, and the electrostatic interactions\nalong DNA backbones are taken into account. Quantitative results are obtained\nby using path integral method, and excellent agreement between theory and the\nobservations reported by five major experimental groups are attained. The\nstrong intensity of the base-stacking interactions ensures the structural\nstability of DNA, while the short-ranged nature of such interactions makes\nexternally-stimulated large structural fluctuations possible. The entropic\nelasticity, highly extensibility, and supercoiling property of DNA are all\nclosely related to this account. The present work also suggests the possibility\nthat negative torque can induce structural transitions in highly extended DNA\nfrom right-handed B-form to left-handed configurations similar with Z-form\nconfiguration. Some formulae concerned with the application of path integral\nmethod to polymeric systems are listed in the Appendix.",
        "positive": "Softness, anomalous dynamics, and fractal-like energy landscape in model\n  cell tissues: Epithelial cell tissues have a slow relaxation dynamics resembling that of\nsupercooled liquids. Yet, they also have distinguishing features. These include\nan extended short-time sub-diffusive transient, as observed in some experiments\nand recent studies of model systems, and a sub-Arrhenius dependence of the\nrelaxation time on temperature, as reported in numerical studies. Here we\ndemonstrate that the anomalous glassy dynamics of epithelial tissues originates\nfrom the emergence of a fractal-like energy landscape, particles becoming\nvirtually free to diffuse in specific phase space directions up to a small\ndistance. Furthermore, we clarify that the stiffness of the cells tunes this\nanomalous behaviour, tissues of stiff cells having conventional glassy\nrelaxation dynamics."
    },
    {
        "anchor": "Shear Banding of Soft Glassy Materials in Large Amplitude Oscillatory\n  Shear: We study shear banding in soft glassy materials subject to a large amplitude\noscillatory shear flow (LAOS). By numerical simulations of the widely used soft\nglassy rheology model, supplemented by more general physical arguments, we\ndemonstrate strong banding over an extensive range of amplitudes and\nfrequencies of the imposed shear rate\n$\\dot{\\gamma}(t)=\\dot{\\gamma}_0\\cos(\\omega t)$, even in materials that do not\npermit banding as their steady state response to a steady imposed shear flow\n$\\dot{\\gamma}=\\dot{\\gamma}_0=$const. Highly counterintuitively, banding\npersists in LAOS even in the limit of zero frequency $\\omega\\to 0$, where one\nmight a priori have expected a homogeneous flow response (consistent with the\nrequirement of homogeneous flow for a strictly zero frequency steady imposed\nshear flow). We explain this finding in terms of an alternating competition\nwithin each cycle between glassy aging and flow rejuvenation. Our predictions\nhave far-reaching implications for the flow behavior of aging yield stress\nfluids, suggesting a generic expectation of shear banding in flows of even\narbitrarily slow time variation.",
        "positive": "A study of structural organization of water and aqueous solutions by\n  means of optical microscopy: It is shown that structuring at the microlevel, a previously not described in\ndetail phenomenon, is the intrinsic property of water and aqueous solutions. At\nroom conditions water (including \"ultrapure\" one) and aqueous solutions are\ndispersed systems in which microcrystals of NaCl, surrounded by a layer of\nhydrated water (average diameter - 10-15 microns), are \"elementary\nmicroparticles\", which form the basis of the dispersed phase. Possible ways of\nformation of these microparticles and their evolution in the process of\nevaporation of unstructured part of water - dispersion medium - are considered.\nIt is shown, in particular, that they are present in the air as aerosol\ncontaminants. When the ionic strength of the solution increases, the water-salt\nparticles aggregate, forming a new phase - coacervates, remaining on the\nsubstrate after evaporation of the liquid part of the water. The aggregates of\ncoacervate structures, formed in a liquid medium, are disordered during\nheating, which can cause a change in a number of physicochemical properties of\nwater at the temperatures of 50{\\deg}-60{\\deg}C range that have not been\ncorrectly explained in the framework of atomic-molecular concepts."
    },
    {
        "anchor": "Effective Electrostatic Interactions in Solutions of Polyelectrolyte\n  Stars with Rigid Rodlike Arms: In solutions of star-branched polyelectrolytes, electrostatic interactions\nbetween charged arms on neighboring stars can compete with intra-star\ninteractions and rotational entropy to induce anisotropy in the orientational\ndistribution of arms. For model stars comprising rigid rodlike arms with evenly\nspaced charged monomers interacting via an effective screened-Coulomb (Yukawa)\npotential, we explore the influence of arm orientational anisotropy on\neffective star-star interactions. Monte Carlo simulation and density-functional\ntheory are used to compute arm orientational distributions and effective pair\npotentials between weakly charged stars. The degree of anisotropy is found to\nincrease with the strength of electrostatic interactions and proximity of the\nstars. As two stars begin to overlap, the forward arms are pushed back by\ninter-star arm-arm repulsion, but partially interdigitate due to rotational\nentropy. At center-center separations approaching complete overlap, the arms\nrelax to an isotropic distribution. For nonoverlapping stars,\nanisotropy-induced changes in intra- and inter-star arm-arm interactions\nlargely cancel and the effective pair interactions are then well approximated\nby a simple Yukawa potential, as predicted by linear response theory for a\ncontinuum model of isotropic stars [A. R. Denton, Phys. Rev. E 67, 11804\n(2003)]. For overlapping stars, the effective pair interactions in the simple\nrigid-arm-Yukawa model agree closely with simulations of a molecular model that\nincludes flexible arms and explicit counterions [A. Jusufi, C. N. Likos, and H.\nLowen, Phys. Rev. Lett. 88, 018301 (2002); J. Chem. Phys. 116, 11011 (2002)].",
        "positive": "Phase behavior of wormlike rods: By employing Molecular Dynamics computer simulations, the phase behavior of\nsystems of rodlike particles with varying degree of internal flexibility has\nbeen traced from the perfectly rigid rod limit till very flexible particles,\nand from the high density region till the isotropic phase. From the perfectly\nrigid rod limit and enhancing the internal flexibility, the range of the\nsmectic A phase is squeezed out by the concomitant action of the scarcely\naffected crystalline phase at higher density and the nematic phase at lower\ndensity, until it disappears. These results confirm the supposition, drawn from\nprevious theoretical, simulational and experimental studies, that the smectic A\nphase is destabilized by introducing and enhancing the degree of particle\ninternal flexibility. However, no significant changes in the order of\nnematic--to--smectic A phase transition, which appears always first order, nor\nin the value of the layer spacing, are observed upon varying the degree of\nparticle internal flexibility. Moreover, no evidence of a columnar phase, which\nwas tought of as a possible superseder of the smectic A phase in flexible rods,\nhas been obtained."
    },
    {
        "anchor": "A numerical renormalization group study of laser induced freezing: We study the phenomenon of laser induced freezing, within a numerical\nrenormalization scheme which allows explicit comparison with a recent defect\nmediated melting theory. Precise values for the `bare' dislocation fugacities\nand elastic moduli of the 2-d hard disk system are obtained from a constrained\nMonte Carlo simulation sampling only configurations {\\em without} dislocations.\nThese are used as inputs to appropriate renormalization flow equations to\nobtain the equilibrium phase diagram which shows excellent agreement with\nearlier simulation results. We show that the flow equations need to be correct\nat least up to third order in defect fugacity to reproduce meaningful results.",
        "positive": "The effects of added salt on the second virial coefficients of the\n  complete proteome of E. coli: Bacteria typically have a few thousand different proteins. The number of\nproteins with a given charge is a roughly Gaussian function of charge - centred\nnear zero, and with a width around ten (in units of the charge on the proton).\nWe have used the charges on E. coli's proteins to estimate the changes in the\nsecond virial coefficients of all its proteins as the concentration of a 1:1\nsalt is increased. The second virial coefficient has dimensions of volume and\nwe find that on average it decreases by about twice the average volume of a\nprotein when the salt concentration is increased from 0.2 to 1 Molar. The\nstandard deviation of the decrease is of the same order. The consequences of\nthis for the complex mixture of proteins inside an E. coli cell, are briefly\ndiscussed."
    },
    {
        "anchor": "Controlling cell motion and microscale flow with polarized light fields: We investigate how light polarization affects the motion of photo-responsive\nalgae, \\textit{Euglena gracilis}. In a uniformly polarized field, cells swim\napproximately perpendicular to the polarization direction and form a nematic\nstate with zero mean velocity. When light polarization varies spatially, cell\nmotion is modulated by local polarization. In such light fields, cells exhibit\ncomplex spatial distribution and motion patterns which are controlled by\ntopological properties of the underlying fields; we further show that ordered\ncell swimming can generate directed transporting fluid flow. Experimental\nresults are quantitatively reproduced by an active Brownian particle model in\nwhich particle motion direction is nematically coupled to local light\npolarization.",
        "positive": "Optical correlation techniques for the investigation of colloidal\n  systems: This review aims to provide a simple introduction to the application of\noptical correlation methods in colloidal science. In particular, I plan to show\nthat full appraisal of the intimate relation between light scattering and\nmicroscopy allows designing novel powerful investigation techniques that\ncombine their powers. An extended version of this paper will appear in\n\"ColloidalFoundations of Nanoscience\", edited by D. Berti and G. Palazzo,\nElsevier (ISBN 978-0-444-59541-6). I am very grateful to the publisher for\nhaving granted me the permission to post this preprint on arXiv."
    },
    {
        "anchor": "Quantifying the relevance of long-range forces for crystal nucleation in\n  water: Understanding nucleation from aqueous solutions is of fundamental importance\nin a multitude of fields, ranging from materials science to biophysics. The\ncomplex solvent-mediated interactions in aqueous solutions hamper the\ndevelopment of a simple physical picture elucidating the roles of different\ninteractions in nucleation processes. In this work we make use of three\ncomplementary techniques to disentangle the role played by short and long-range\ninteractions in solvent mediated nucleation. Specifically, the first approach\nwe utilize is the local molecular field (LMF) theory to renormalize long-range\nCoulomb electrostatics. Secondly, we use well-tempered metadynamics to speed up\nrare events governed by short-range interactions. Thirdly, deep learning-based\nState Predictive Information Bottleneck approach is employed in analyzing the\nreaction coordinate of the nucleation processes obtained from LMF treatment\ncoupled with well-tempered metadynamics. We find that the two-step nucleation\nmechanism can largely be captured by the short-range interactions, while the\nlong-range interactions further contribute to the stability of the primary\ncrystal state at ambient conditions. Furthermore, by analyzing the reaction\ncoordinate obtained from combined LMF-metadynamics treatment, we discern the\nfluctuations on different time scales, highlighting the need for long-range\ninteractions when accounting for metastability.",
        "positive": "Counterions at Charged Cylinders: Criticality and universality beyond\n  mean-field: The counterion-condensation transition at charged cylinders is studied using\nMonte-Carlo simulation methods. Employing logarithmically rescaled radial\ncoordinates, large system sizes are tractable and the critical behavior is\ndetermined by a combined finite-size and finite-ion-number analysis. Critical\ncounterion localization exponents are introduced and found to be in accord with\nmean-field theory both in 2 and 3 dimensions. In 3D the heat capacity shows a\nuniversal jump at the transition, while in 2D, it consists of discrete peaks\nwhere single counterions successively condense."
    },
    {
        "anchor": "Athermal granular creep in a quenched sandpile: Creep is a generic descriptor of slow motions -- in the context of materials,\nit describes quasi-static deformation of a solid when subjected to stresses\nbelow the global yield, at which all rigidity collapses and the material flows.\nHere, we experimentally investigate creep, flow, and the transition between the\ntwo states in a granular heap flow. Within the surface flowing layer the\ndimensionless strain rate diminishes with depth, there is an absence of spatial\ncorrelations, and there is no aging dynamics. Beneath this layer, the bulk\ncreeps via localized avalanches of plasticity, and there is significant aging.\nThe transition between fast surface flow and slow bulk creep and aging is\nobserved to be in the vicinity of a critical inertial number of $I = 10^{-5}$.\nSurprisingly, at the cessation of surface flow and the `quenching' of the pile,\ncreep persists in the absence of the flowing layer; albeit with significant\ndifferences for a pile that experiences a long duration of surface flow\n(strongly annealed) and one where flow during preparation does not last long\n(weakly annealed). Our results contribute to an emerging view of athermal\ngranular creep, showing similarities across dry and submerged systems. Quenched\nquiescent heaps that creep indefinitely, however, present a challenge to\ngranular rheology, and open new possibilities for interpreting and casting\ncreep and deformation of soils in nature.",
        "positive": "Comment on: `Pipe Network Model for Scaling of Dynamic Interfaces in\n  Porous Media': We argue that a proposed exponent identity [Phys. Rev. Lett 85, 1238 (2000)]\nfor interface roughening in spontaneous imbibition is wrong. It rests on the\nassumption that the fluctuations are controlled by a single time scale, but\nliquid conservation imposes two distinct time scales."
    },
    {
        "anchor": "Enhanced Elasticity and Soft Glassy Rheology of a Smectic in a Random\n  Porous Environment: We report studies of the frequency dependent shear modulus,\n$G^*(\\omega)=G'(\\omega)+iG''(\\omega)$, of the liquid crystal octylcyanobiphenyl\n(8CB) confined in a colloidal aerosil gel. With the onset of smectic order,\n$G'$ grows approximately linearly with decreasing temperature, reaching values\nthat exceed by more than three orders of magnitude the values for pure 8CB. The\nmodulus at low temperatures possesses a power-law component, $G^*(\\omega) \\sim\n\\omega^\\alpha$, with exponent $\\alpha$ that approaches zero with increasing gel\ndensity. The amplitude of $G'$ and its variation with temperature and gel\ndensity indicate that the low temperature response is dominated by a dense\npopulation of defects in the smectic. In contrast, when the 8CB is isotropic or\nnematic, the modulus is controlled by the elastic behavior of the colloidal\ngel.",
        "positive": "Anomalous Power Law Decay in Solvation Dynamics of DNA: A Mode Coupling\n  Theory Analysis of Ion Contribution: Several time domain fluorescence Stokes shift (TDFSS) experiments have\nreported a slow power law decay in the hydration dynamics of a DNA molecule.\nSuch a power law has neither been observed in computer simulations nor in some\nother TDFSS experiments. Here we observe that a slow decay may originate from\ncollective ion contribution because in experiments DNA is immersed in a buffer\nsolution, and also from groove bound water and lastly from DNA dynamics itself.\nIn this work we first express the solvation time correlation function in terms\nof dynamic structure factors of the solution. We use mode coupling theory to\ncalculate analytically the time dependence of collective ionic contribution. A\npower law decay in seen to originate from an interplay between long range\nprobe-ion direct correlation function and ion-ion dynamic structure factor.\nAlthough the power law decay is reminiscent of Debye-Falkenhagen effect yet\nsolvation dynamics is dominated by ion atmosphere relaxation times at longer\nlength scales (small wave number) than in electrolyte friction. We further\ndiscuss why this power law may not originate from water motions which have been\ncomputed by molecular dynamics simulations. Lastly, we propose several\nexperiments to check the prediction of the present theoretical work."
    },
    {
        "anchor": "Multi-Ring Deposition Pattern of Drying Droplets: We propose a theory for the multi-ring pattern of the deposits that are\nformed when droplets of suspension are dried on a substrate. Assuming a\nstandard model for the stick-slip motion of the contact line, we show that as\ndroplets evaporate, many concentric rings of deposits are formed, but are taken\nover by a solid-circle pattern in the final stage of drying. An analytical\nexpression is given to indicate when ring-pattern changes to solid-circle\npattern during an evaporation process. The results are in qualitative agreement\nwith existing experiments, and the other predictions on how the evaporation\nrate, droplet radius and receding contact angle affect the pattern are all\nsubject to experimental test.",
        "positive": "Encoding Mechano-Memories in Actin Networks: Understanding the response of complex materials to external force is central\nto fields ranging from materials science to biology. Here, we describe a novel\ntype of mechanical adaptation in cross-linked networks of F-actin, a\nubuiquitous protein found in eukaryotic cells. We show that shear stress\nchanges its nonlinear mechanical response even long after that stress is\nremoved. The duration, magnitude and direction of forcing history all impact\nchanges in mechanical response. The `memory' of the forcing history is\nlong-lived, but can be erased by force application in the opposite direction.\nWe further show that the observed mechanical adaptation is consistent with\nstress-dependent changes in the nematic order of the constituent filaments.\nThus, this mechano-memory is a type of nonlinear hysteretic response in which\nan applied, \"training\" strain modifies the nonlinear elasticity. This\ndemonstrates that F-actin networks can encode analog read-write\nmechano-memories, which can be used for adaptation to mechanical stimuli."
    },
    {
        "anchor": "Three dimensional hysdrodynamic lattice-gas simulations of binary\n  immiscible and ternary amphiphilic flow through porous media: We report the results of a study of multiphase flow in porous media. A\nDarcy's law for steady multiphase flow was investigated for both binary and\nternary amphiphilic flow. Linear flux-forcing relationships satisfying Onsager\nreciprocity were shown to be a good approximation of the simulation data. The\ndependence of the relative permeability coefficients on water saturation was\ninvestigated and showed good qualitative agreement with experimental data.\nNon-steady state invasion flows were investigated, with particular interest in\nthe asymptotic residual oil saturation. The addition of surfactant to the\ninvasive fluid was shown to significantly reduce the residual oil saturation.",
        "positive": "Onset of mechanical stability in random packings of frictional spheres: Using sedimentation to obtain precisely controlled packings of noncohesive\nspheres, we find that the volume fraction $\\phi_{\\rm RLP}$ of the loosest\nmechanically stable packing is in an operational sense well defined by a limit\nprocess. This random loose packing volume fraction decreases with decreasing\npressure $p$ and increasing interparticle friction coefficient $\\mu$. Using\nX-ray tomography to correct for a container boundary effect that depends on\nparticle size, we find for rough particles in the limit $p \\to 0$ a new lower\nbound, $\\phi_{\\rm RLP} = 0.550 \\pm 0.001$."
    },
    {
        "anchor": "Extreme softness of brain matter in simple shear: We show that porcine brain matter can be modelled accurately as a very soft\nrubber-like material using the Mooney-Rivlin strain energy function, up to\nstrains as high as 60\\%. This result followed from simple shear experiments\nperformed on small rectangular fresh samples ($2.5$ cm$^3$ and $1.1$ cm$^3$) at\nquasi-static strain rates. They revealed a linear shear stress--shear strain\nrelationship ($R^2> 0.97 $), characteristic of Mooney-Rivlin materials at large\nstrains. We found that porcine brain matter is about 30 times less resistant to\nshear forces than a silicone gel. We also verified experimentally that brain\nmatter exhibits the positive Poynting effect of nonlinear elasticity, and\nnumerically that the stress and strain fields remain mostly homogeneous\nthroughout the thickness of the samples in simple shear.",
        "positive": "Anisotropic Hydrodynamic Mean-Field Theory for Semiflexible Polymers\n  under Tension: We introduce an anisotropic mean-field approach for the dynamics of\nsemiflexible polymers under intermediate tension, the force range where a chain\nis partially extended but not in the asymptotic regime of a nearly straight\ncontour. The theory is designed to exactly reproduce the lowest order\nequilibrium averages of a stretched polymer, and treats the full complexity of\nthe problem: the resulting dynamics include the coupled effects of long-range\nhydrodynamic interactions, backbone stiffness, and large-scale polymer contour\nfluctuations. Validated by Brownian hydrodynamics simulations and comparison to\noptical tweezer measurements on stretched DNA, the theory is highly accurate in\nthe intermediate tension regime over a broad dynamical range, without the need\nfor additional dynamic fitting parameters."
    },
    {
        "anchor": "Fluctuation interaction of particles in a fluid: The interaction of bodies in a fluid, mediated by hydrodynamic fluctuations\nand proposed by Dzyaloshinskii, Lifshitz, and Pitaevskii, is calculated exactly\nfor parallel infinite planes and is shown to be attractive. The second\nmechanism of fluctuation interaction, proposed in the present work, is due to\nfluctuations of linear and angular velocities of bodies in a hydrodynamic\nmedium and leads to a repulsion. The both mechanisms provide an interaction\nenergy of two particles in a fluid of the order of temperature for the\ninter-particle distance of the micron scale, where the interaction mediated by\nelectromagnetic fluctuations is small. When two particles approaches a wall,\nplaced inside a fluid, the first (attractive) interaction is violated a little,\nbut the second (repulsive) weakens. This behavior correlates with the\nexperimentally observed attraction of particles which appears when they\napproach a wall.",
        "positive": "Stability of DNA molecule in conical shaped cellular environment: DNA inside the cellular environment works under a confined space. An intense\nresearch of the transcription and replication of DNA in the confined state is\nstructurally significant to command the self assembly of DNA in a chamber or\nchannel. In this work, we consider double stranded DNA (dsDNA) molecules of\ndifferent length and sequence and study the thermal stability of the molecule\nin a confined space of conical geometry. Using the Peyrard-Bishop-Dauxois (PBD)\nmodel, we evaluate the melting profile of dsDNA that is confined on one side of\nthe conical wall that mimics cellular boundary. Our results show that not only\nthe confinement, but also the geometry of the confined space plays a prominent\nrole in the stability of the molecule."
    },
    {
        "anchor": "Understanding the scaling of boson peak through insensitivity of elastic\n  heterogeneity to bending rigidity in polymer glasses: Amorphous materials exhibit peculiar mechanical and vibrational properties,\nincluding non-affine elastic responses and excess vibrational states, i.e., the\nso-called boson peak. For polymer glasses, these properties are considered to\nbe affected by the bending rigidity of the constituent polymer chains. In our\nrecent work [Tomoshige, et al., Sci. Rep. 9 19514 (2019)], we have revealed\nsimple relationships between the variations of vibrational properties and the\nglobal elastic properties: the response of the boson peak scales only with that\nof the global shear modulus. This observation suggests that the spatial\nheterogeneity of the local shear modulus distribution is insensitive to changes\nin the bending rigidity. Here, we demonstrate the insensitivity of elastic\nheterogeneity by directly measuring the local shear modulus distribution. We\nalso study transverse sound wave propagation, which is also shown to scale only\nwith the global shear modulus. Through these analyses, we conclude that the\nbending rigidity does not alter the spatial heterogeneity of the local shear\nmodulus distribution, which yields vibrational and acoustic properties that are\ncontrolled solely by the global shear modulus of a polymer glass.",
        "positive": "Response of a polymer network to the motion of a rigid sphere: In view of recent microrheology experiments we re-examine the problem of a\nrigid sphere oscillating inside a dilute polymer network. The network and its\nsolvent are treated using the two-fluid model. We show that the dynamics of the\nmedium can be decomposed into two independent incompressible flows. The first,\ndominant at large distances and obeying the Stokes equation, corresponds to the\ncollective flow of the two components as a whole. The other, governing the\ndynamics over an intermediate range of distances and following the Brinkman\nequation, describes the flow of the network and solvent relative to one\nanother. The crossover between these two regions occurs at a dynamic length\nscale which is much larger than the network's mesh size. The analysis focuses\non the spatial structure of the medium's response and the role played by the\ndynamic crossover length. We examine different boundary conditions at the\nsphere surface. The large-distance collective flow is shown to be independent\nof boundary conditions and network compressibility, establishing the robustness\nof two-point microrheology at large separations. The boundary conditions that\nfit the experimental results for inert spheres in entangled F-actin networks\nare those of a free network, which does not interact directly with the sphere.\nClosed-form expressions and scaling relations are derived, allowing for the\nextraction of material parameters from a combination of one- and two-point\nmicrorheology. We discuss a basic deficiency of the two-fluid model and a way\nto bypass it when analyzing microrheological data."
    },
    {
        "anchor": "Mass changes the diffusion coefficient of particles with ligand-receptor\n  contacts in the overdamped limit: Inertia does not generally affect the long-time diffusion of passive\noverdamped particles in fluids. Yet a model starting from the Langevin equation\npredicts a surprising property of particles coated with ligands, that bind\nreversibly to surface receptors -- heavy particles diffuse more slowly than\nlight ones of the same size. We show this by simulation and by deriving an\nanalytic formula for the mass-dependent diffusion coefficient in the overdamped\nlimit. We estimate the magnitude of this effect for a range of biophysical\nligand-receptor systems, and find it is potentially observable for tailored\nmicronscale DNA-coated colloids.",
        "positive": "Rheology and microstructure of unsaturated granular materials:\n  Experiments and simulations: When dealing with unsaturated wet granular materials, a fundamental question\nis: what is the effect of capillary cohesion on the bulk flow and yield\nbehavior? We inwestigate the dense flow rheology of unsaturated granular\nmaterials through experiments and discrete element simulations of homogeneous,\nsimple annular shear flows of frictional, cohesive, spherical particles."
    },
    {
        "anchor": "High frequency poroelastic waves in hydrogels: In this work a continuum model for high frequency poroelastic longitudinal\nwaves in hydrogels is presented. A viscoelastic force describing the\ninteraction between the polymer network and the bounded water present in such\nmaterials is introduced. The model is tested by means of ultrasound wave speed\nand attenuation measurements in polyvinylalcohol hydrogel samples. The theory\nand experiments show that ultrasound attenuation decreases linearly with the\nincrease of the water volume fraction \"{\\beta}\" of the hydrogel. The\nintroduction of the viscoelastic force between the bounded water and the\npolymer network leads to a bi-phasic theory showing an ultrasonic fast wave\nattenuation that can vary as a function of the frequency with a non-integer\nexponent in agreement with the experimental data in literature. When {\\beta}\ntends to 1 (100% of interstitial water) due to the presence of bounded water in\nthe hydrogel, the ultrasound phase velocity acquires higher value than that of\npure water. The ultrasound speed gap at {\\beta} = 1 is confirmed by the\nexperimental results that show that it increases in less cross-linked gel\nsamples that own a higher concentration of bounded water.",
        "positive": "Learning minimal representations of stochastic processes with\n  variational autoencoders: Stochastic processes have found numerous applications in science, as they are\nbroadly used to model a variety of natural phenomena. Due to their intrinsic\nrandomness and uncertainty, they are however difficult to characterize. Here,\nwe introduce an unsupervised machine learning approach to determine the minimal\nset of parameters required to effectively describe the dynamics of a stochastic\nprocess. Our method builds upon an extended $\\beta$-variational autoencoder\narchitecture. By means of simulated datasets corresponding to paradigmatic\ndiffusion models, we showcase its effectiveness in extracting the minimal\nrelevant parameters that accurately describe these dynamics. Furthermore, the\nmethod enables the generation of new trajectories that faithfully replicate the\nexpected stochastic behavior. Overall, our approach enables for the autonomous\ndiscovery of unknown parameters describing stochastic processes, hence\nenhancing our comprehension of complex phenomena across various fields."
    },
    {
        "anchor": "Energy flow between two hydrodynamically coupled particles kept at\n  different effective temperatures: We measure the energy exchanged between two hydrodynamically coupled\nmicron-sized Brownian particles trapped in water by two optical tweezers. The\nsystem is driven out of equilibrium by random forcing the position of one of\nthe two particles. The forced particle behaves as it has an \"effective\ntemperature\" higher than that of the other bead. This driving modifies the\nequilibrium variances and cross-correlation functions of the bead positions: we\nmeasure an energy flow between the particles and an instantaneous\ncross-correlation, proportional to the effective temperature difference between\nthe two particles. A model of the interaction which is based on classical\nhydrodynamic coupling tensors is proposed. The theoretical and experimental\nresults are in excellent agreement.",
        "positive": "The Effects of Inter-particle Attractions on Colloidal Sedimentation: We use a mesoscopic simulation technique to study the effect of short-ranged\ninter-particle attraction on the steady-state sedimentation of colloidal\nsuspensions. Attractions increase the average sedimentation velocity $v_s$\ncompared to the pure hard-sphere case, and for strong enough attractions, a\nnon-monotonic dependence on the packing fraction $\\phi$ with a maximum velocity\nat intermediate $\\phi$ is observed. Attractions also strongly enhance\nhydrodynamic velocity fluctuations, which show a pronounced maximum size as a\nfunction of $\\phi$. These results are linked to a complex interplay between\nhydrodynamics and the formation and break-up of transient many-particle\nclusters."
    },
    {
        "anchor": "Nanoscale Rigidity in Cross-Linked Micelle Networks Revealed by XPCS\n  Nanorheology: Solutions of wormlike micelles can form cross-linked networks on microscopic\nlength scales. The unique mechanical properties of these complex fluids are\ndriven by the interplay between the network structure and dynamics which are\ninvestigated by plate-plate rheometry and X-ray photon correlation\nspectroscopy~(XPCS) nanorheology. Intensity auto-correlation functions of\ntracer nanoparticles~(NPs) dispersed in micelle solutions were recorded which\ncaptured both the slow structural network relaxation and the short-time\ndynamics of NPs trapped in the network. The results are indicative of a\nresonance-like dynamic behavior of the network on the nanoscale that develops\nas a consequence of the intrinsic short-range rigidity of individual micelle\nchains.",
        "positive": "Self-assembly of two-dimensional binary quasicrystals: A possible route\n  to a DNA quasicrystal: We use Monte Carlo simulations and free-energy techniques to show that binary\nsolutions of penta- and hexavalent two-dimensional patchy particles can form\nthermodynamically stable quasicrystals even at very narrow patch widths,\nprovided their patch interactions are chosen in an appropriate way. Such patchy\nparticles can be thought of as a coarse-grained representation of DNA multi-arm\n`star' motifs, which can be chosen to bond with one another very specifically\nby tuning the DNA sequences of the protruding arms. We explore several possible\ndesign strategies and conclude that DNA star tiles that are designed to\ninteract with one another in a specific but not overly constrained way could\npotentially be used to construct soft quasicrystals in experiment. We verify\nthat such star tiles can form stable dodecagonal motifs using oxDNA, a\nrealistic coarse-grained model of DNA."
    },
    {
        "anchor": "Wetting hysteresis induced by nanodefects: Wetting of actual surfaces involves diverse hysteretic phenomena stemming\nfrom ever-present imperfections. Here we clarify the origin of wetting\nhysteresis for a liquid front advancing or receding across an isolated defect\nof nanometric size. Various kinds of chemical and topographical nanodefects are\ninvestigated which represent salient features of actual heterogeneous surfaces.\nThe most probable wetting path across surface heterogeneities is identified by\ncombining, within an innovative approach, microscopic classical density\nfunctional theory and the string method devised for the study of rare events.\nThe computed rugged free energy landscape demonstrates that hysteresis emerges\nas a consequence of metastable pinning of the liquid front at the defects; the\nbarriers for thermally activated defect crossing, the pinning force, and\nhysteresis are quantified and related to the geometry and chemistry of the\ndefects allowing for the occurrence of nanoscopic effects. The main result of\nour calculations is that even weak nanoscale defects, which are difficult to\ncharacterize in generic microfluidic experiments, can be the source of a\nplethora of hysteretical phenomena, including the pinning of nanobubbles.",
        "positive": "Effective elasticity of a flexible filament bound to a deformable\n  cylindrical surface: We use numerical simulations to show how a fully flexible filament binding to\na deformable cylindrical surface may acquire a macroscopic persistence length\nand a helical conformation. This is a result of the nontrivial elastic response\nto deformations of elastic sheets. We find that the filament's helical pitch is\ncompletely determined by the mechanical properties of the surface, and can be\ntuned by varying the filament binding energy. We propose simple scaling\narguments to understand the physical mechanism behind this phenomenon and\npresent a phase diagram indicating under what conditions one should expect a\nfully flexible chain to behave as a helical semi-flexible filament. Finally, we\ndiscuss the implications of our results."
    },
    {
        "anchor": "Proteins in solution: Fractal surfaces in solutions: The concept of the surface of a protein in solution, as well of the interface\nbetween protein and 'bulk solution', is introduced. The experimental technique\nof small angle X-ray and neutron scattering is introduced and described\nbriefly. Molecular dynamics simulation, as an appropriate computational tool\nfor studying the hydration shell of proteins, is also discussed. The concept of\nprotein surfaces with fractal dimensions is elaborated. We finish by exposing\nan experimental (using small angle X-ray scattering) and a computer simulation\ncase study, which are meant as demonstrations of the possibilities we have at\nhand for investigating the delicate interfaces that connect (and divide)\nprotein molecules and the neighboring electrolyte solution.",
        "positive": "Can amphiphile architecture directly control vesicle size?: Bilayer membranes self-assembled from simple amphiphiles in solution always\nhave a planar ground-state shape. This is a consequence of several internal\nrelaxation mechanisms of the membrane and prevents the straightforward control\nof vesicle size. Here, we show that this principle can be circumvented and that\ndirect size control by molecular design is a realistic possibility. Using\ncoarse-grained calculations, we design tetrablock copolymers that form\nmembranes with a preferred curvature, and demonstrate how to form\nlow-polydispersity vesicles while suppressing micellization."
    },
    {
        "anchor": "Wall slip and bulk yielding in soft particle suspensions: We simulate a dense athermal suspension of soft particles sheared between\nhard walls of a prescribed roughness profile, using a method that fully\naccounts for the fluid mechanics of the solvent between the particles, and\nbetween the particles and the walls, as well as for the solid mechanics of\nchanges in the particle shapes. We thus capture the widely observed phenomenon\nof elastohydrodynamic wall slip, in which the soft particles become deformed in\nshear and lift away from the wall slightly, leaving behind a thin lubricating\nsolvent layer of high shear. For imposed stresses below the material's bulk\nyield stress, we show the observed wall slip to be dominated by this thin\nsolvent layer. At higher stresses, it is augmented by an additional\ncontribution arising from a fluidisation of the first few layers of particles\nnear the wall. By systematically varying the roughness of the walls, we\nquantify a suppression of slip with increasing wall roughness. For smooth\nwalls, slip radically changes the steady state bulk flow curve of shear stress\nas a function of shear rate, by conferring a branch of apparent (slip-induced)\nflow even for $\\sigma<\\sigma_y$, as seen experimentally. We also elucidate the\neffects of slip on the dynamics of yielding following the imposition of a\nconstant shear stress, characterising the timescales at which bulk yielding\narises, and at which slip first sets in.",
        "positive": "Engineering the geometry of stripe-patterned surfaces towards efficient\n  wettability switching: The ability to control wettability is important for a wide range of\ntechnological applications in which precise microfluidic handling is required.\nIt is known that predesigned roughness at a micro- or nano- scale enhances the\nwetting properties of solid materials giving rise to super-hydrophobic or\nsuper-hydrophilic behavior. In this work, we study the dependence of the\napparent wettability of a stripe-patterned solid surface on the stripe\ngeometry, utilizing systems level analysis and mesoscopic Lattice-Boltzmann\n(LB) simulations. Through the computation of both stable and unstable states we\nare able to determine the energy barriers separating distinct metastable\nwetting states that correspond to the well-known Cassie and Wenzel states. This\nway the energy cost for inducing certain wetting transitions is computed and\nits dependence on geometric features of the surface pattern is explored."
    },
    {
        "anchor": "Coiling Instabilities in Multilamellar Tubes: Myelin figures are densely packed stacks of coaxial cylindrical bilayers that\nare unstable to the formation of coils or double helices. These myelin figures\nappear to have no intrinsic chirality. We show that such cylindrical membrane\nstacks can develop an instability when they acquire a spontaneous curvature or\nwhen the equilibrium distance between membranes is decreased. This instability\nbreaks the chiral symmetry of the stack and may result in coiling. A\nunilamellar cylindrical vesicle, on the other hand, will develop an\naxisymmetric instability, possibly related to the pearling instability.",
        "positive": "Single particle motion and collective dynamics in Janus motor systems: The single-particle and collective dynamics of systems comprising Janus\nmotors, solvent and reactive solute species maintained in nonequilibrium states\nare investigated. Reversible catalytic reactions with the solute species take\nplace on the catalytic faces of the motors, and the nonequilibrium states are\nestablished by imposing either constant-concentration reservoirs that feed and\nremove reactive species, or through out-of-equilibrium fluid phase reactions.\nWe consider general intermolecular interactions between the Janus motor\nhemispheres and the reactive species. For single motors, we show that the\nreaction rate depends nonlinearly on an applied external force when the system\nis displaced far from equilibrium. We also show that a finite-time fluctuation\nformula derived for fixed catalytic particles describes the nonequilibrium\nreactive fluctuations of moving Janus motors. Simulation of the collective\ndynamics of small ensembles of Janus motors with reversible kinetics under\nnonequilibrium conditions are carried out and the spatial and orientational\ncorrelations of dynamic cluster states are discussed. The conditions leading to\nthe instability of the homogeneous motor distribution and the onset of\nnonequilibrium dynamical clustering are described."
    },
    {
        "anchor": "Macroscopic charge segregation in driven polyelectrolyte solutions: Understanding the behavior of charged complex fluids is crucial for a\nplethora of important industrial, technological, and medical applications.\nUsing coarse-grained molecular dynamics simulations, here we investigate the\nproperties of a polyelectrolyte solution, with explicit counterions and\nimplicit solvent, that is driven by a steady electric field. By properly tuning\nthe interplay between interparticle electrostatics and the applied electric\nfield, we uncover two nonequilibrium continuous phase transitions as a function\nof the driving field. The first transition occurs from a homogeneously mixed\nphase to a macroscopically charge segregated phase, in which the\npolyelectrolyte solution self-organizes to form two lanes of like-charges,\nparallel to the applied field. We show that the fundamental underlying factor\nresponsible for the emergence of this charge segregation in the presence of\nelectric field is the excluded volume interactions of the drifting\npolyelectrolyte chains. As the drive is increased further, a re-entrant\ntransition is observed from a charge segregated phase to a homogeneous phase.\nThe re-entrance is signaled by the decrease in mobility of the monomers and\ncounterions, as the electric field is increased. Furthermore, with multivalent\ncounterions, a counterintuitive regime of negative differential mobility is\nobserved, in which the charges move progressively slower as the driving field\nis increased. We show that all these features can be consistently explained by\nan intuitive trapping mechanism that operates between the oppositely moving\ncharges, and present numerical evidence to support our claims. Parameter\ndependencies and phase diagrams are studied to better understand charge\nsegregation in such driven polyelectrolyte solutions.",
        "positive": "Collapse and cavitation during drying of water-saturated PDMS sponges\n  with closed porosity: In this paper, we study the drying of water-saturated porous\npolydimethylsiloxane (PDMS) elastomers with closed porosity in which the\nevaporation of water is possible only via the diffusion across the PDMS.\nStarting from water/PDMS emulsions, we fabricate soft macroporous samples with\ndifferent pore diameter distributions and average diameters ranging from 10 to\n300 $\\mu$m. In these materials, the drying may lead either to a collapsed state\nwith low porosity or to the cavitation and reopening of a fraction of the\npores. Using optical microscopy and porosity measurements, we showed the\nimportance of the pore diameters and interactions on the result of drying. At\npore diameters lower than 30 $\\mu$m, the majority of pores remain collapsed. We\nattribute the permanence of the collapse of most small pores to a low\nprobability of cavitation and to the adhesion of the pore walls. Pores with\ndiameters larger than 100 $\\mu$m tend to reopen after the water they contain\ncavitates. The behavior of pores with diameters ranging from 30 to 100 $\\mu$m\ndepends on the porosity and drying temperature. We also visualize collective\ncavitation upon drying of sponges initially saturated with a sodium chloride\nsolution. In this case, the cavitation in the largest pores leads to reopening\nof small pores in a neighboring zone of the sample. To our knowledge, our\nresults present the first experimental proof of the pore-size-dependent and\ncooperative nature of the response of soft sponges with closed porosity to\ndrying."
    },
    {
        "anchor": "Stress overshoot in a simple yield stress fluid: an extensive study\n  combining rheology and velocimetry: We report a large amount of experimental data on the stress overshoot\nphenomenon which takes place during start-up shear flows in a simple yield\nstress fluid, namely a carbopol microgel. A combination of classical\nrheological measurements and ultrasonic velocimetry makes it possible to get\nphysical insights on the transient dynamics of both the stress $\\sigma(t)$ and\nthe velocity field across the gap of a rough cylindrical Couette cell during\nthe start-up of shear under an applied shear rate $\\dot\\gamma$. (i) At small\nstrains ($\\gamma <1$), $\\sigma(t)$ increases linearly and the microgel\nundergoes homogeneous deformation. (ii) At a time $t_m$, the stress reaches a\nmaximum value $\\sigma_m$ which corresponds to the failure of the microgel and\nto the nucleation of a thin lubrication layer at the moving wall. (iii) The\nmicrogel then experiences a strong elastic recoil and enters a regime of total\nwall slip while the stress slowly decreases. (iv) Total wall slip gives way to\na transient shear-banding phenomenon, which occurs on timescales much longer\nthan that of the stress overshoot and has been described elsewhere [Divoux\n\\textit{et al., Phys. Rev. Lett.}, 2010, \\textbf{104}, 208301]. This whole\nsequence is very robust to concentration changes in the explored range ($0.5\n\\le C \\le 3%$ w/w). We further demonstrate that the maximum stress $\\sigma_m$\nand the corresponding strain $\\gamma_m=\\dot\\gamma t_m$ both depend on the\napplied shear rate $\\dot \\gamma$ and on the waiting time $t_w$ between preshear\nand shear start-up: they remain roughly constant as long as $\\dot\\gamma$ is\nsmaller than some critical shear rate $\\dot\\gamma_w\\sim 1/t_w$ and they\nincrease as weak power laws of $\\dot \\gamma$ for $\\dot\\gamma> \\dot\\gamma_w$\n[...].",
        "positive": "Microparticle transport networks with holographic optical tweezers and\n  cavitation bubbles: Optical transport networks for active absorbing microparticles are made with\nholographic optical tweezers. The particles are powered by the optical\npotentials that make the network and transport themselves via random vapor\npropelled hops to different traps without the requirement for external forces\nor microfabricated barriers. The geometries explored for the optical traps are\nsquare lattices, circular arrays and random arrays. The degree distribution for\nthe connections or possible paths between the traps are localized like in the\ncase of random networks. The commute times to travel across $n$ different traps\nscale as $n^2$, in agreement with random walks on connected networks. Once a\nparticle travels the network, others are attracted as a result of the vapor\nexplosions."
    },
    {
        "anchor": "Adhesion and non-linear rheology of adhesives with supramolecular\n  crosslinking points: Soft supramolecular materials are promising for the design of innovative and\nhighly tunable adhesives. These materials are composed of polymer chains\nfunctionalized by strongly interacting moieties, sometimes called \"stickers\".\nIn order to systematically investigate the effect of the presence of\nassociative groups on the debonding properties of a supramolecular adhesive, a\nseries of supramolecular model systems has been characterized by probe-tack\ntests. These model materials, composed of linear and low dispersity\npoly(butylacrylate) chains functionalized in the middle by a single tri-urea\nsticker, are able to self-associate by six hydrogen bonds and range in\nmolecular weight (M n) between 5 and 85 kg/mol. The linear rheology and the\nnanostructure of the same materials (called \"PnBA3U\") was the object of a\nprevious study 1,2. At room temperature, the association of polymers via\nhydrogen bonds induces the formation of rod-like aggregates structured into\nbundles for M n \\textless{} 40kg/mol and the behavior of a soft elastic\nmaterial was observed (G'\\textgreater{}\\textgreater{}G \"and G'~$\\omega$ 0). For\nhigher M n , the filaments were randomly oriented and polymers displayed a\ncrossover towards viscous behavior although terminal relaxation was not reached\nin the experimental frequency window. All these materials show however similar\nadhesive properties characterized by a cohesive mode of failure and low\ndebonding energies (W adh \\textless{}40J/m 2 for a debonding speed of\n100$\\mu$m/s). The debonding mechanisms observed during the adhesion tests have\nbeen investigated in detail with an Image tools analysis developed by our group\n3. The measure of the projected area covered by cavities growing in the\nadhesive layer during debonding can be used to estimate the true stress in the\nwalls of the cavities and thus, to characterize the in-situ large strain\ndeformation of the thin layer during the adhesion test itself. This analysis\nrevealed in particular that the PnBA3U materials with M n \\textless{} 40 kg/mol\nsoften very markedly at large deformation like yield stress fluids, explaining\nthe low adhesion energies measured for these viscoelastic gels. 2",
        "positive": "Spreading, shrinking and fingering instability of polymer films in glow\n  discharge: Spontaneous spreading of a polymer drop on a solid substrate can be forced by\na low pressure gaseous discharge applied between the cathode that supports the\ndrop and a remote electrode. We prone to think that the driving force for this\nplasma driven spreading is the spatial distribution of the electric field at\nthe cathode. Two distinct effects caused by the gas plasma are observed:\nspreading of a thin film and shrinking of the rest liquid into a spherical drop\nupon its own film. The last effect, never reported before, can be addressed to\nthe effect of the electric stresses developed in the ionic double layer formed\nat the polymer/plasma interface. The spreading front displays a fingering\ninstability similar to that observed earlier in various experimental conditions\n\\cite{troian,melo}. Theoretical analysis shows that the Marangoni stress acts\nas the driving force for the finger growth."
    },
    {
        "anchor": "Rapid accumulation of colloidal microspheres flowing over\n  microfabricated barriers: Accumulation of particles while flowing past constrictions is a ubiquitous\nphenomenon observed in diverse systems. Some of the common examples are jamming\nof salt crystals near the orifice of salt shakers, clogging of filter systems,\ngridlock in traffics etc. For controlled studies, accumulation events are often\nexamined as clogging process in microfluidic channels. Experimental studies\nthus far have provided with various physical insights, however, they fail to\naddress commonly encountered accumulation events relevant to human health such\nas dental and arterial plaques. We simulate arterial plaque like accumulation\nevents by flowing colloidal microspheres over micro-structured barriers in\nmicrofluidic environment. Our experiments reveal the role of electrostatic,\ncontact and hydrodynamic forces in facilitating plaque-like build up events. A\ndecrease in Debye length (electrostatic repulsion) between interacting surface\nby two orders leads to only a minor increase in accumulation. In contrast, an\nincrease in the roughness by 3 times results in dramatic rise of accumulation.",
        "positive": "Thermodynamic scaling of vibrational dynamics and relaxation: We investigate by thorough Molecular Dynamics simulations the thermodynamic\nscaling (TS) of a polymer melt. Two distinct models, with strong and weak\nvirial-energy correlations, are considered. Both evidence the joint TS with the\nsame characteristic exponent $\\gamma_{ts}$ of the fast mobility - the mean\nsquare amplitude of the picosecond rattling motion inside the cage -, and the\nmuch slower structural relaxation and chain reorientation. If the cage effect\nis appreciable, the TS master curves of the fast mobility are nearly linear,\ngrouping in a bundle of approximately concurrent lines for different\nfragilities. An expression of the TS master curve of the structural relaxation\nwith one adjustable parameter less than the available three-parameters\nalternatives is derived. The novel expression fits well with the experimental\nTS master curves of thirty-four glassformers and, in particular, their slope at\nthe glass transition, i.e. the isochoric fragility. For the glassformer OTP the\nisochoric fragility allows to satisfactorily predict the TS master curve of the\nfast mobility with no adjustments."
    },
    {
        "anchor": "Demixing behavior in two-dimensional mixtures of anisotropic hard bodies: Scaled particle theory for a binary mixture of hard discorectangles and for a\nbinary mixture of hard rectangles is used to predict possible liquid-crystal\ndemixing scenarios in two dimensions. Through a bifurcation analysis from the\nisotropic phase, it is shown that isotropic-nematic demixing is possible in\ntwo-dimensional liquid-crystal mixtures composed of hard convex bodies. This\nbifurcation analysis is tested against exact calculations of the phase diagrams\nin the framework of the restricted-orientation two-dimensional model (Zwanzig\nmodel). Phase diagrams of a binary mixture of hard discorectangles are\ncalculated through the parametrization of the orientational distribution\nfunctions. The results show not only isotropic-nematic, but also\nnematic-nematic demixing ending in a critical point, as well as an\nisotropic-nematic-nematic triple point for a mixture of hard disks and hard\ndiscorectangles.",
        "positive": "Disclination motion in hexatic and smectic-C films: We present theoretical study of a single disclination motion in a thin free\nstanding hexatic (or smectic-C) film, driven by a large-scale inhomogeneity in\nthe bond (or director) angle. Back-flow effects and own dynamics of the bond\nangle are included. We find the angle and hydrodynamic velocity distributions\naround the moving disclination, what allows us to relate the disclination\nvelocity to the angle gradient far from the disclination. Different cases are\nexamined depending on the ratio of the rotational and shear viscosity\ncoefficients."
    },
    {
        "anchor": "L\u00e9vy Fluctuations and Tracer Diffusion in Dilute Suspensions of Algae\n  and Bacteria: Swimming microorganisms rely on effective mixing strategies to achieve\nefficient nutrient influx. Recent experiments, probing the mixing capability of\nunicellular biflagellates, revealed that passive tracer particles exhibit\nanomalous non-Gaussian diffusion when immersed in a dilute suspension of\nself-motile Chlamydomonas reinhardtii algae. Qualitatively, this observation\ncan be explained by the fact that the algae induce a fluid flow that may\noccasionally accelerate the colloidal tracers to relatively large velocities. A\nsatisfactory quantitative theory of enhanced mixing in dilute active\nsuspensions, however, is lacking at present. In particular, it is unclear how\nnon-Gaussian signatures in the tracers' position distribution are linked to the\nself-propulsion mechanism of a microorganism. Here, we develop a systematic\ntheoretical description of anomalous tracer diffusion in active suspensions,\nbased on a simplified tracer-swimmer interaction model that captures the\ntypical distance scaling of a microswimmer's flow field. We show that the\nexperimentally observed non-Gaussian tails are generic and arise due to a\ncombination of truncated L\\'evy statistics for the velocity field and\nalgebraically decaying time correlations in the fluid. Our analytical\nconsiderations are illustrated through extensive simulations, implemented on\ngraphics processing units to achieve the large sample sizes required for\nanalyzing the tails of the tracer distributions.",
        "positive": "Effect of plasticity and dimensionality on crumpling of a thin sheet: The process of crumpling a sheet and compacting it into a ball is dependent\non many parameters that are difficult to disentangle. We study the effect of\nplasticity on the crumpling process, and disentangle the effects of plasticity\nand dimensionality of compaction by performing isotropic compaction experiments\non various materials with different elastoplasticities. The force required to\ncrumple a sheet into a ball as well as the number of layers inside the ball\nhave a power-law dependence on the size of the crumpled ball, each with its own\npower-law exponent. We experimentally determine both exponents and find that\nthey are linearly proportional to and decrease with increasing plasticity of\nthe material. Finally we provide a scaling argument predicting a linear\nrelation between the two exponents with a coefficient of 3.5 in excellent\nagreement with our experimental results."
    },
    {
        "anchor": "Recent advances in structural and dynamical propertiesof simplified\n  industrial nanocomposites: A large body of experimental work on the microstructure and dynamics of\nsimplifiedindustrial nanocomposites made of disordered silica filler in a\nstyrene-butadiene matrixby solid-phase mixing is regrouped and critically\ndiscussed in this feature article. Recentresults encompass systems with varying\npolymer mass, grafting functionality, and fillercontent. They have been\nobtained by simulation-based structural modelling of nanoparticleaggregate size\nand mass deduced from small-angle scattering and transmission\nelectronmicroscopy. Our model has been validated by independent swelling\nexperiments.Comparison of structurally-close nanocomposites of widely different\nchain mass led tothe identification of a unique structure-determining\nparameter, the grafting density, aswell as to a unified picture of aggregate\nformation mechanisms in complex nanocompositesduring mixing. In addition,\nlow-field proton NMR allowed for the characterization ofdynamically slowed-down\n('glassy') polymer layers, which were shown not to dominatethe rheological\nresponse, unlike the structural contribution. Finally, broadband\ndielectricspectroscopy was used in an innovative manner to identify filler\npercolation -- also identifiedby rheology -- via dynamics along filler\nsurfaces.",
        "positive": "Kinetics Of Vapor-Liquid And Vapor-Solid Phase Separation Under Gravity: We study the kinetics of vapor-liquid and vapor-solid phase separation of a\nhydrodynamics preserving three-dimensional one component Lennard Jones system\nin the presence of external gravitational field using extensive molecular\ndynamic simulation. A bicontinuous domain structure is formed when the\nhomogeneous system near the critical density is quenched inside the coexistence\nregion. In the absence of gravity, the domain morphology is statistically\nself-similar and the length scale grows as per the existing laws. However, the\npresence of gravity destroys the isotropy of the system and affects the scaling\nlaws. We observe an accelerated domain growth in the direction of the field at\nlate time which resembles sedimentation process. Consequently, a new length\nscale emerges which strongly depends on the field strength. Similar behavior is\nobserved in the direction perpendicular to the applied field, with a different\ngrowth rate. Finally, the validity of Porod's law and Superuniversality in such\nanisotropic systems is verified in terms of two-point equal time order\nparameter correlation function and static structure factor."
    },
    {
        "anchor": "Topological protection can arise from thermal fluctuations and\n  interactions: Topological quantum and classical materials can exhibit robust properties\nthat are protected against disorder, for example for noninteracting particles\nand linear waves. Here, we demonstrate how to construct topologically protected\nstates that arise from the combination of strong interactions and thermal\nfluctuations inherent to soft materials or miniaturized mechanical structures.\nSpecifically, we consider fluctuating lines under tension (e.g., polymer or\nvortex lines), subject to a class of spatially modulated substrate potentials.\nAt equilibrium, the lines acquire a collective tilt proportional to an integer\ntopological invariant called the Chern number. This quantized tilt is robust\nagainst substrate disorder, as verified by classical Langevin dynamics\nsimulations. This robustness arises because excitations in this system of\nthermally fluctuating lines are gapped by virtue of inter-line interactions. We\nestablish the topological underpinning of this pattern via a mapping that we\ndevelop between the interacting-lines system and a hitherto unexplored\ngeneralization of Thouless pumping to imaginary time. Our work points to a new\nclass of classical topological phenomena in which the topological signature\nmanifests itself in a structural property observed at finite temperature rather\nthan a transport measurement.",
        "positive": "Jerky active matter: a phase field crystal model with translational and\n  orientational memory: Most field theories for active matter neglect effects of memory and inertia.\nHowever, recent experiments have found inertial delay to be important for the\nmotion of self-propelled particles. A major challenge in the theoretical\ndescription of these effects, which makes the application of standard methods\nvery difficult, is the fact that orientable particles have both translational\nand orientational degrees of freedom which do not necessarily relax on the same\ntime scale. In this work, we derive the general mathematical form of a field\ntheory for soft matter systems with two different time scales. This allows to\nobtain a phase field crystal model for polar (i.e., nonspherical or active)\nparticles with translational and orientational memory. Notably, this theory is\nof third order in temporal derivatives and can thus be seen as a spatiotemporal\njerky dynamics. We obtain the phase diagram of this model, which shows that,\nunlike in the passive case, the linear stability of the liquid state depends on\nthe damping coefficients. Moreover, we investigate sound waves in active\nmatter. It is found that, in active fluids, there are two different mechanisms\nfor sound propagation. For certain parameter values and sufficiently high\nfrequencies, sound mediated by polarization waves experiences less damping than\nusual passive sound mediated by pressure waves of the same frequency. By\ncombining the different modes, acoustic frequency filters based on active\nfluids could be realized."
    },
    {
        "anchor": "In search of a precursor for crystal nucleation of hard and charged\n  colloids: The interplay between crystal nucleation and the structure of the metastable\nfluid has been a topic of significant debate over recent years. In particular,\nit has been suggested that even in simple model systems such as hard or charged\ncolloids, crystal nucleation might be foreshadowed by significant fluctuations\nin local structure around the location where the first nucleus arises. We\ninvestigate this using computer simulations of spontaneous nucleation events in\nboth hard and charged colloidal particles. To detect local structural\nvariations, we use both standard and unsupervised machine learning methods\ncapable of finding hidden structures in the metastable fluid phase. We track\nnumerous nucleation events for the face-centered cubic and body-centered cubic\ncrystal on a local level, and demonstrate that all signs of crystallinity\nemerge simultaneously from the very start of the nucleation process. We thus\nconclude that there is no precursor for the nucleation of charged colloids.",
        "positive": "Formation of dodecagonal quasicrystals in two-dimensional systems of\n  patchy particles: The behaviour of two-dimensional patchy particles with 5 and 7\nregularly-arranged patches is investigated by computer simulation. For higher\npressures and wider patch widths, hexagonal crystals have the lowest enthalpy,\nwhereas at lower pressures and for narrower patches, lower-density crystals\nwith five nearest neighbours and that are based on the (3^2,4,3,4) tiling of\nsquares and triangles become lower in enthalpy. Interestingly, in regions of\nparameter space near to that where the hexagonal crystals become stable,\nquasicrystalline structures with dodecagonal symmetry form on cooling from high\ntemperature. These quasicrystals can be considered as tilings of squares and\ntriangles, and are probably stabilized by the large configurational entropy\nassociated with all the different possible such tilings. The potential for\nexperimentally realizing such structures using DNA multi-arm motifs are\ndiscussed."
    },
    {
        "anchor": "Thermodynamic and transport anomalies near isotropic-nematic phase\n  transition: A theoretical study of the variation of thermodynamic and transport\nproperties of calamitic liquid crystals across the isotropic-nematic phase\ntransition is carried out by calculating the {\\it wavenumber (k) and time (t)}\ndependent intermediate scattering function of the liquid, via computer\nsimulations of model nematogens. The objective is to understand the\nexperimentally observed anomalies and sharp variation in many thermodynamic and\ntransport properties, namely specific heat $C$, sound attenuation coefficient\n$\\Gamma$, thermal diffusivity $D_T$ and sound velocity $c_s$ are as the I-N\ntransition is approached from the isotropic side. The small wavelength limit of\nthe calculated intermediate scattering function $F(k,t)$ is used to obtain the\nratio of specific heats $\\gamma$ and other properties mentioned above. We find\nthat all of them show non-monotonic variations near the I-N transition, with\n$\\Gamma$ showing a cusp-like behavior. We suggest that the observed anomalous\nfeatures are a direct consequence of the existence of pseudo-nematic domains in\nthe system near the phase boundary and the melting and formation of such\ndomains give rise to sound attenuation and also to the observed specific heat\nanomaly. A theoretical description of these anomalies should invoke\ntranslation-rotation coupling at molecular level. While the heterogeneous\ndynamics observed here bear resemblance to that in deeply supercooled liquids\nnear glass transition, the thermodynamic anomalies articulated here are largely\nabsent in supercooled liquids.",
        "positive": "Decoding chirality in circuit topology of a self entangled chain through\n  braiding: Circuit topology employs fundamental units of entanglement, known as soft\ncontacts, for constructing knots from the bottom up, utilising circuit topology\nrelations, namely parallel, series, cross, and concerted relations. In this\narticle, we further develop this approach to facilitate the analysis of\nchirality, which is a significant quantity in polymer chemistry. To achieve\nthis, we translate the circuit topology approach to knot engineering into a\nbraid-theoretic framework. This enables us to calculate the Jones polynomial\nfor all possible binary combinations of contacts in cross or concerted\nrelations and to show that, for series and parallel relations, the polynomial\nfactorises. Our results demonstrate that the Jones polynomial provides a\npowerful tool for analysing the chirality of molecular knots constructed using\ncircuit topology. The framework presented here can be used to design and\nengineer a wide range of entangled chain with desired chiral properties, with\npotential applications in fields such as materials science and nanotechnology."
    },
    {
        "anchor": "The explicit secular equation for surface acoustic waves in monoclinic\n  elastic crystals: The secular equation for surface acoustic waves propagating on a monoclinic\nelastic half-space is derived in a direct manner, using the method of first\nintegrals. Although the motion is at first assumed to correspond to generalized\nplane strain, the analysis shows that only two components of the mechanical\ndisplacement and of the tractions on planes parallel to the free surface are\nnonzero. Using the Stroh formalism, a system of two second order differential\nequations is found for the remaining tractions. The secular equation is then\nobtained as a quartic for the squared wave speed. This explicit equation is\nconsistent with that found in the orthorhombic case. The speed of subsonic\nsurface waves is then computed for twelve specific monoclinic crystals.",
        "positive": "From ageing to immortality: cluster growth in stirred colloidal\n  solutions: This model describes cluster aggregation in a stirred colloidal solution\nInteracting clusters compete for growth in this 'winner-takes-all' model; for\nfinite assemblies, the largest cluster always wins, i.e. there is a uniform\nsediment. In mean-field, the model exhibits glassy dynamics, with two\nwell-separated time scales, corresponding to individual and collective\nbehaviour; the survival probability of a cluster eventually falls off according\nto a universal law $(\\ln t)^{-1/2}$. In finite dimensions, the glassiness is\nenhanced: the dynamics manifests both {\\it ageing} and metastability, where\npattern formation is manifested in each metastable state by a fraction of {\\it\nimmortal} clusters."
    },
    {
        "anchor": "Efficient creation of molecules from a cesium Bose-Einstein condensate: We report a new scheme to create weakly bound Cs$_2$ molecules from an atomic\nBose-Einstein condensate. The method is based on switching the magnetic field\nto a narrow Feshbach resonance and yields a high atom-molecule conversion\nefficiency of more than 30%, a factor of three higher than obtained with\nconventional magnetic-field ramps. The Cs$_2$ molecules are created in a single\n$g$-wave rotational quantum state. The observed dependence of the conversion\nefficiency on the magnetic field and atom density shows scattering processes\nbeyond two-body coupling to occur in the vicinity of the Feshbach resonance.",
        "positive": "An investigation of the SCOZA for narrow square-well potentials and in\n  the sticky limit: We present a study of the self consistent Ornstein-Zernike approximation\n(SCOZA) for square-well (SW) potentials of narrow width delta. The main purpose\nof this investigation is to elucidate whether in the limit delta --> 0, the\nSCOZA predicts a finite value for the second virial coefficient at the critical\ntemperature B2(Tc), and whether this theory can lead to an improvement of the\napproximate Percus-Yevick solution of the sticky hard-sphere (SHS) model due to\nBaxter [R. J. Baxter, J. Chem. Phys. 49, 2770 (1968)]. For SW of non vanishing\ndelta, the difficulties due to the influence of the boundary condition at high\ndensity already encountered in an earlier investigation [E. Schoell-Paschinger,\nA. L. Benavides, and R. Castaneda-Priego, J. Chem. Phys. 123, 234513 (2005)]\nprevented us from obtaining reliable results for delta < 0.1. In the sticky\nlimit this difficulty can be circumvented, but then the SCOZA fails to predict\na liquid-vapor transition. The picture that emerges from this study is that for\ndelta --> 0, the SCOZA does not fulfill the expected prediction of a constant\nB2(Tc) [M. G. Noro and D. Frenkel, J. Chem. Phys. 113, 2941 (2000)], and that\nfor thermodynamic consistency to be usefully exploited in this regime, one\nshould probably go beyond the Ornstein-Zernike ansatz."
    },
    {
        "anchor": "Electrostatic interaction between colloids with constant surface\n  potentials at fluid interfaces: In this thesis, the electrostatic interaction between two chemically\nidentical colloids, both carrying constant surface potential is studied in the\nlimit of short inter-particle separation at the interface of two immiscible\nfluids. Using an appropriate model system, the problem is solved analytically\nwithin the framework of linearized Poisson-Boltzmann theory and classical\ndensity functional theory. The governing equation of the electrostatic problem\nis derived by minimization of the corresponding density functional, which leads\nto the Debye-H\\\"uckel equation. Subsequently, the Debye-H\\\"uckel equation is\nsolved by exact calculations as well as by applying the widely used\nsuperposition approximation, each providing expressions for the electrostatic\npotential distribution inside the system. Furthermore, the obtained results of\nthe electrostatic problem are used to calculate surface and line interaction\nenergy densities between the colloidal particles. In all cases, the\nsuperposition approximation fails to predict the interaction energies correctly\nfor both small and large separations. Additionally, analytic expressions for\nthe surface tensions, line tension, and interfacial tension, which are all\nindependent of the inter-particle separation, are obtained. The results of this\nthesis are expected to enrich the description of electrostatic interaction\nbetween colloids at fluid interfaces.",
        "positive": "Slow dynamic nonlinearity in unconsolidated glass bead packs: Slow dynamic nonlinearity describes a poorly understood, creep-like phenomena\nthat occurs in brittle composite materials such as rocks and cement. It is\ncharacterized by a drop in stiffness induced by a mechanical conditioning,\nfollowed by a log(time) recovery. A consensus theoretical understanding of the\nbehavior has not been developed. Here we introduce an alternative experimental\nvenue with which to inform theory. Unconsolidated glass bead packs are studied\nrather than rocks or cement because the structure and internal contacts of bead\npacks are less complex and better understood. Slow dynamics has been observed\nin such systems previously. However, the measurements to date tend to be\nirregular. Particular care is used here in the experimental design to overcome\nthe difficulties inherent in bead pack studies. This includes the design of the\nbead pack support, the use of low frequency conditioning, and the use of\nultrasonic waves as a probe with coda wave interferometry to assess changes.\nSlow dynamics is observed in our system after three different methods for\nlow-frequency conditioning, one of which has not been reported in the\nliterature previously."
    },
    {
        "anchor": "Ground state lost but degeneracy found: the effective thermodynamics of\n  artificial spin ice: We analyze the rotational demagnetization of artificial spin ice, a recently\nrealized array of nanoscale single-domain ferromagnetic islands.\nDemagnetization does not anneal this model system into its anti-ferromagnetic\nground state: the moments have a static disordered configuration similar to the\nfrozen state of the spin ice materials. We demonstrate that this athermal\nsystem has an effective extensive degeneracy and we introduce a formalism that\ncan predict the populations of local states in this ice-like system with no\nadjustable parameters.",
        "positive": "A correlation-hole approach to the electric double layer with\n  counter-ions only: We study a classical system of identically charged counter-ions near a planar\nwall carrying a uniform surface charge density. The equilibrium statistical\nmechanics of the system depends on a single dimensionless coupling parameter. A\nnew self-consistent theory of the correlation-hole type is proposed which leads\nto a modified Poisson-Boltzmann integral equation for the density profile,\nconvenient for analytical progress and straightforward to solve numerically.\nThe exact density profiles are recovered in the limits of weak and strong\ncouplings. In contrast to previous theoretical attempts of the test-charge\nfamily, the density profiles fulfill the contact-value theorem at all values of\nthe coupling constant, and exhibit the mean-field decay at asymptotically large\ndistances from the wall, as expected. We furthermore show that the density\ncorrections at large couplings exhibit the proper dependence on coupling\nparameter and distance to the charged wall. The numerical results for\nintermediate values of the coupling provide accurate density profiles which are\nin good agreement with those obtained by Monte-Carlo simulations. The crossover\nto mean-field behavior at large distance is studied in detail."
    },
    {
        "anchor": "Pattern selection and the route to turbulence in incompressible polar\n  active fluids: Active fluids, such as suspensions of microswimmers, are known to\nself-organize into complex spatio-temporal flow patterns. An intriguing example\nis mesoscale turbulence, a state of dynamic vortex structures exhibiting a\ncharacteristic length scale. Here, we employ a minimal model for the effective\nmicroswimmer velocity field to explore how the turbulent state develops from\nregular vortex patterns when the strength of activity resp. related parameters\nsuch as nonlinear advection or polar alignment strength - is increased. First,\nwe demonstrate analytically that the system, without any spatial constraints,\ndevelops a stationary square vortex lattice in the absence of nonlinear\nadvection. Subsequently, we perform an extended stability analysis of this\nnonuniform \"ground state\" and uncover a linear instability, which follows from\nthe mutual excitement and simultaneous growth of multiple perturbative modes.\nThis extended analysis is based on linearization around an approximation of the\nanalytical vortex lattice solution and allows us to calculate critical activity\nparameters. Above these critical values, the vortex lattice develops into\nmesoscale turbulence in numerical simulations. Utilizing the numerical\napproach, we uncover an extended region of hysteresis where both patterns are\npossible depending on the initial condition. Here, we find that turbulence\npersists below the instability of the vortex lattice. We further determine the\nstability of square vortex patterns as a function of their wavenumber and\nrepresent the results analogous to the well-known Busse balloons known from\nclassical pattern-forming systems. Here, the region of stable periodic patterns\nshrinks and eventually disappears with increasing activity parameters. Our\nresults show that the strength of activity plays a similar role for active\nturbulence as the Reynolds number does in driven flow exhibiting inertial\nturbulence.",
        "positive": "Slippery and mobile hydrophobic electrokinetics: from single walls to\n  nanochannels: We discuss how the wettability of solid walls impacts electrokinetic\nproperties, from large systems to a nanoscale. We show in particular how could\nthe hydrophobic slippage, coupled to confinement effects, be exploited to\ninduce novel electrokinetic properties, such as a salt-dependent giant\namplification of zeta potential and conductivity, and a much more efficient\nenergy conversion. However, the impact of slippage is dramatically reduced if\nsome surface charges migrate along the hydrophobic wall under an applied field."
    },
    {
        "anchor": "Rotation Control, Interlocking and Self-positioning of Active Cogwheels: Gears and cogwheels restrain degrees of freedom and channel power into a\nspecified motion. They are fundamental components of macroscopic machines.\nInterlocking microrotors similarly constitute key elements toward feasible\nmicromachinery. Their assembly, positioning and control is a challenge at\nmicroscale, where noise is ubiquituous. Here, we show the assembly and control\nof a family of self-spinning cogwheels with varying teeth numbers and study\ninterlocking mechanisms in systems of multiple cogwheels. The cogwheels are\nautonomous and active, with teeth formed by colloidal microswimmers that power\nthe structure, and control its rotation rate. Leveraging the angular momentum\nof light with optical vortices, we control the direction of rotation of the\ncogwheels. We study pairs of interlocking cogwheels, that roll over each other\nin a random walk and curvature-dependent mobility. We leverage this feature to\nachieve self-positioning of cogwheels on structures with variable curvature and\nprogram microbots, notably demonstrating the ability to pick up, displace and\nrelease a load. This work highlights untapped opportunities of manufacturing at\nmicroscale using self-positioning components and constitutes an important step\ntowards autonomous and programmable microbots.",
        "positive": "Confined crowded polymers near attractive surfaces: We present results from molecular dynamics simulations of a spherically\nconfined neutral polymer in the presence of crowding agents, studying polymer\nshapes and conformations as a function of the confining potential, solvent\nquality and the density of crowders. The conformations of the polymer under\ngood solvent conditions are largely independent of crowder density, even when\nthe polymer is strongly confined. However, for poor solvents and attractive\nwalls, the polymer shows a transition between an adsorbed extended state to a\nglobular conformation on the surface as a function of crowder particle density.\nThis state differs from both the desorbed globular conformation in the absence\nof any wall interactions and the adsorbed globular conformation at low values\nof the attractive wall interactions. We revisit the earlier understanding of\nthe adsorption of confined polymers on curved, attractive surfaces in the light\nof these results."
    },
    {
        "anchor": "Two dimensional self-assembly of inverse patchy colloids: We report on the self-assembly of inverse patchy colloids (IPC) using Monte\nCarlo simulations in two-dimensions. The IPC model considered in this work\ncorresponds to either bipolar colloids or colloids decorated with complementary\nDNA on their surfaces, where only patch and non-patch parts attract. The patch\ncoverage is found to be a dominant factor in deciding equilibrium\nself-assembled structures. In particular, both regular square and triangular\ncrystals are found to be stable at 0.5 patch coverage. Upon decreasing the\npatch coverage to 0.33, the regular square crystal is destablized; instead\nrhombic and triangular crystals are found to be stable. At low patch coverages\nsuch as 0.22 and 0.12, only triangular crystal is stabilized at high density.\nParticles of all the patch coverages show kinetically stable cluster phases of\ndifferent shape and size, and the average cluster sizes are found to strongly\ndepend on the patch coverage and particle density. State-diagrams showing all\nthe stable phases for each patch coverage are presented. Ordered phases are\ncharacterized by bond order parameters {\\psi}4, {\\psi}6 and radial distribution\nfunction. The effect on patch coverage on polarization of the stable structures\nare also studied. The study demonstrates that inverse patchy colloids are\npotential candidates to form various ordered two-dimensional structures by\ntuning the size of the patch.",
        "positive": "Dynamical Crystallites of Active Chiral Particles: One of the intrinsic characteristics of far-from-equilibrium systems is the\nnonrelaxational nature of the system dynamics, which leads to novel properties\nthat cannot be understood and described by conventional pathways based on\nthermodynamic potentials. Of particular interest are the formation and\nevolution of ordered patterns composed of active particles that exhibit\ncollective behavior. Here we examine such a type of nonpotential active system,\nfocusing on effects of coupling and competition between chiral particle\nself-propulsion and self-spinning. It leads to the transition between three\nbulk dynamical regimes dominated by collective translative motion,\nspinning-induced structural arrest, and dynamical frustration. In addition, a\npersistently dynamical state of self-rotating crystallites is identified as a\nresult of a localized-delocalized transition induced by the crystal-melt\ninterface. The mechanism for the breaking of localized bulk states can also be\nutilized to achieve self-shearing or self-flow of active crystalline layers."
    },
    {
        "anchor": "Integral equation study of soft-repulsive dimeric fluids: We study fluid structure and water-like anomalies of a system constituted by\ndimeric particles interacting via a purely repulsive core-softened potential by\nmeans of integral equation theories. In our model, dimers interact through a\nrepulsive pair potential of inverse-power form with a softened repulsion\nstrength. By employing the Ornstein-Zernike approach and the reference\ninteraction site model (RISM) theory, we study the behavior of water-like\nanomalies upon progressively increasing the elongation {\\lambda} of the dimers\nfrom the monomeric case ({\\lambda} = 0) to the tangent configuration ({\\lambda}\n= 1). For each value of the elongation we consider two different values of the\ninteraction potential, corresponding to one and two length scales, with the aim\nto provide a comprehensive description of the possible fluid scenarios of this\nmodel. Our theoretical results are systematically compared with already\nexisting or newly generated Monte Carlo data: we find that theories and\nsimulations agree in providing the picture of a fluid exhibiting density and\nstructural anomalies for low values of {\\lambda} and for both the two values of\nthe interaction potential. Integral equation theories give accurate predictions\nfor pressure and radial distribution functions, whereas the temperatures where\nanomalies occur are underestimated. Upon increasing the elongation, the RISM\ntheory still predicts the existence of anomalies; the latter are no longer\nobserved in simulations, since their development is likely precluded by the\nonset of crystallization. We discuss our results in terms of the reliability of\nintegral equation theories in predicting the existence of water-like anomalies\nin core-softened fluids.",
        "positive": "Distinguishing failure modes at the molecular level by examining\n  heterogeneity in local structures and dynamics: Brittle failure is ubiquitous in amorphous materials that are sufficiently\ncooled below their glass transition temperature, $T_g$. This catastrophic\nfailure mode is limiting for amorphous materials in many applications, and many\nfundamental questions surrounding it remain poorly understood. Two challenges\nthat prevent a more fundamental understanding of the transition between a\nductile response at temperatures near $T_g$ to brittle failure at lower\ntemperatures are i) a lack of computationally inexpensive molecular models that\ncapture the failure modes observed in experiments and ii) the lack of\nquantitative metrics that can distinguish various failure mechanisms. In this\nwork, we use molecular dynamics simulations to capture ductile-to-brittle\ntransition in glass-forming short-chain polymer systems by using a modified\nLennard-Jones potential to describe non-bonded interactions between the\nmonomers. We characterized the effects of this new potential on macroscopic\nmechanical properties as well as microscopic structural and dynamical\ndifferences during deformation. Lastly, we present quantitative metrics that\ndistinguish between different failure modes."
    },
    {
        "anchor": "Finite wavelength surface-tension driven instabilities in soft solids,\n  including instability in a cylindrical channel through an elastic solid: We deploy linear stability analysis to find the threshold wavelength\n($\\lambda$) and surface tension ($\\gamma$) of Rayleigh-Plateau type\n\"peristaltic\" instabilities in incompressible neo-Hookean solids in a range of\ncylindrical geometries with radius $R_0$. First we consider a solid cylinder,\nand recover the well-known, infinite wavelength instability for $\\gamma\\ge6 \\mu\nR_0$, where $\\mu$ is the solid's shear modulus. Second, we consider a\nvolume-conserving (e.g.\\ fluid filled and sealed) cylindrical cavity through an\ninfinite solid, and demonstrate infinite wavelength instability for $\\gamma\\ge\n2 \\mu R_0$. Third, we consider a solid cylinder embedded in a different\ninfinite solid, and find a finite wavelength instability with $\\lambda\\propto\nR_0$, at surface tension $\\gamma \\propto \\mu R_0$, where the constants depend\non the two solids' modulus ratio. Finally, we consider an empty cylindrical\nchannel (or filled with expellable fluid) through an infinite solid, and find\nan instability with finite wavelength, $\\lambda \\approx2 R_0$, for $\\gamma\\ge\n2.543... \\mu R_0$. Using finite-strain numerics, we show such a channel jumps\nat instability to a highly peristaltic state, likely precipitating it's\nblockage or failure. We argue that finite wavelengths are generic for\nelasto-capillary instabilities, with the simple cylinder's infinite wavelength\nbeing the exception rather than the rule.",
        "positive": "Multi-scale microrheology using fluctuating filaments as stealth probes: The mechanical properties of soft materials can be probed on small length\nscales by various microrheology methods. A common approach tracks fluctuations\nof micrometer-sized beads embedded in the medium to be characterized. This\napproach yields results that depend on the probe size when the medium has\nstructure on length scales comparable to or larger than this size. Here, we\nintroduce a filament-based microrheology (FMR) method using high-aspect-ratio\nsemi-flexible filaments as probes. Such quasi-1D probes are much less invasive\ndue to the nanometer-scale cross section of the probes. Moreover, by imaging\nthe transverse bending modes, we are able to simultaneously determine the\nmicromechanical response of the medium on multiple length scales corresponding\nbending wavelengths. Here, we use single-walled carbon nanotubes (SWNT) as\nprobes that can be accurately and rapidly imaged based on their stable\nfluorescence. We model SWNTs as semi-flexible filaments. We find that the\nviscoelastic properties of sucrose and polymeric hyaluronic acid solutions\nmeasured in this way are in good agreement with those measured by conventional\nmicro- and macrorheology."
    },
    {
        "anchor": "Disentanglement Effects on the Welding Behaviour of Polymer Melts during\n  the Fused-Filament-Fabrication Method for Additive Manufacturing: Although 3D printing has the potential to transform manufacturing processes,\nthe strength of printed parts often does not rival that of\ntraditionally-manufactured parts. The fused-filament fabrication method\ninvolves melting a thermoplastic, followed by layer-by-layer extrusion of the\nmolten viscoelastic material to fabricate a three-dimensional object. The\nstrength of the welds between layers is controlled by interdiffusion and\nentanglement of the melt across the interface. However, diffusion slows down as\nthe printed layer cools towards the glass transition temperature. Diffusion is\nalso affected by high shear rates in the nozzle, which significantly deform and\ndisentangle the polymer microstructure prior to welding. In this paper, we\nmodel non-isothermal polymer relaxation, entanglement recovery, and diffusion\nprocesses that occur post-extrusion to investigate the effects that typical\nprinting conditions and amorphous (non-crystalline) polymer rheology have on\nthe ultimate weld structure. Although we find the weld thickness to be of the\norder of the polymer size, the structure of the weld is anisotropic and\nrelatively disentangled; reduced mechanical strength at the weld is attributed\nto this lower degree of entanglement.",
        "positive": "Coalescence Model for Crumpled Globules Formed in Polymer Collapse: The rapid collapse of a polymer, due to external forces or changes in\nsolvent, yields a long-lived `crumpled globule.' The conjectured fractal\nstructure shaped by hierarchical collapse dynamics has proved difficult to\nestablish, even with large simulations. To unravel this puzzle, we study a\ncoarse-grained model of in-falling spherical blobs that coalesce upon contact.\nDistances between pairs of monomers are assigned upon their initial\ncoalescence, and do not `equilibrate' subsequently. Surprisingly, the model\nreproduces quantitatively the dependence of distance on segment length,\nsuggesting that the slow approach to scaling is related to the wide\ndistribution of blob sizes."
    },
    {
        "anchor": "Digital Microfluidics? How Magnetically Driven Orientation of Pillars\n  Influences Droplet Positioning: Interfaces between a water droplet and a network of pillars produce\neventually superhydrophobic, self-cleaning properties. Considering the surface\nfraction of the surface in interaction with water, it is possible to tune\nprecisely the contact angle hysteresis (CAH) to low values, which is at the\norigin of the poor adhesion of water droplets, inducing their high mobility on\nsuch a surface. However, if one wants to move and position a droplet, the lower\nthe CAH, the less precise will be the positioning on the surface. While rigid\nsurfaces limit the possibilities of actuation, smart surfaces have been devised\nwith which a stimulus can be used to trigger the displacement of a droplet.\nLight, electron beam, mechanical stimulation like vibration, or magnetism can\nbe used to induce a displacement of droplets on surfaces and transfer them from\none position to the targeted one. Among these methods, only few are reversible,\nleading to anisotropy-controlled orientation of the structured interface with\nwater. Magnetically driven superhydrophobic surfaces are the most promising\nreprogramming surfaces that can lead to the control of wettability and droplet\nguidance.",
        "positive": "Fragile to strong crossover coupled to liquid-liquid transition in\n  hydrophobic solutions: Using discrete molecular dynamics simulations we study the relation between\nthe thermodynamic and diffusive behaviors of a primitive model of aqueous\nsolutions of hydrophobic solutes consisting of hard spheres in the Jagla\nparticles solvent, close to the liquid-liquid critical point of the solvent. We\nfind that the fragile-to-strong dynamic transition in the diffusive behavior is\nalways coupled to the low-density/high-density liquid transition. Above the\nliquid-liquid critical pressure, the diffusivity crossover occurs at the Widom\nline, the line along which the thermodynamic response functions show maxima.\nBelow the liquid-liquid critical pressure, the diffusivity crossover occurs\nwhen the limit of mechanical stability lines are crossed, as indicated by the\nhysteresis observed when going from high to low temperature and vice versa.\nThese findings show that the strong connection between dynamics and\nthermodynamics found in bulk water persists in hydrophobic solutions for\nconcentrations from low to moderate, indicating that experiments measuring the\nrelaxation time in aqueous solutions represent a viable route for solving the\nopen questions in the field of supercooled water."
    },
    {
        "anchor": "Copolymer at a selective interface and two dimensional wetting: a grand\n  canonical approach: We consider two different problems involving the localization of a single\npolymer chain: (i) a periodic $AB$ copolymer at a selective fluid-fluid\ninterface, with the upper (resp. lower) fluid attracting $A$ (resp. $B$)\nmonomers (ii) a homopolymer chain attracted to a hard wall (wetting). Self\navoidance is neglected in both models, which enables us to study their\nlocalization transition in a grand canonical approach. We recover the results\nobtained in previous studies via transfer matrix methods. Moreover, we\ncalculate in this way the loop length distribution functions in the localized\nphase. Some finite size effects are also determined and tested numerically.",
        "positive": "Entropy change due to stochastic state transitions of odd Langevin\n  system: Active microscopic objects, e.g., an enzyme molecule, are modeled by the odd\nLangevin system, in which energy injection from the substrate to the enzyme is\ndescribed by the antisymmetric part of the elastic matrix. By applying the\nOnsager-Machlup integral and large deviation theory to the odd Langevin system,\nwe can calculate the cumulant generating function of the entropy change of a\nthermal bath due to the state transition. For an $N$-component system, we\nobtain a formal expression of the cumulant generating function and demonstrate\nthat the oddness $\\lambda$, which quantifies the antisymmetric part of the\nelastic matrix, leads to higher-order cumulants that do not appear in a passive\nelastic system. To demonstrate the effect of the oddness under the concrete\nparameter, we analyze the simplest two-component system and obtain the optimal\ntransition path and cumulant generating function. The cumulants obtained from\nexpansion of the cumulant generating function increase monotonically with the\noddness. This implies that the oddness causes the uncertainty of stochastic\nstate transitions."
    },
    {
        "anchor": "Fluidic Endogenous Magnetism and Magnetic Monopole Clues from Liquid\n  Metal Droplet Machine: Magnetism and magnetic monopole are classical issues in basic physics.\nConventional magnets are generally composed of rigid materials with shapes and\nstructures unchangeable which may face challenges sometimes to answer the above\nquestions. Here, from an alternative other than rigid magnet, we disclosed an\nunconventional way to generate endogenous magnetism and then construct magnetic\nmonopole through tuning liquid metal machine. Through theoretical\ninterpretation and conceptual experiments, we illustrated that when gallium\nbase liquid metal in solution rotates under actuation of an external electric\nfield, it forms an endogenous magnetic field inside which well explains the\nphenomenon that two such discrete metal droplets could easily fuse together,\nindicating their reciprocal attraction via N and S poles. Further, we conceived\nthat the self-driving liquid metal motor was also an endogenous magnet owning\nthe electromagnetic homology. When liquid metal in solution swallowed aluminum\ninside, it formed a spin motor and dynamically variable charge distribution\nwhich produced an endogenous magnetic field. This finding explains the\nphenomena that there often happened reflection collision and attraction fusion\nbetween running liquid metal motors which were just caused by the dynamic\nadjustment of their N and S polarities. Finally, we conceived that such\nendogenous magnet could lead to magnetic monopole and four technical routes\nwere suggested as: 1. Matching the interior flow field of liquid metal\nmachines; 2. Superposition between external electric effect and magnetic field;\n3. Composite construction between magnetic particles and liquid metal motor; 4.\nChemical ways such as via galvanic cell reaction. Overall, the fluidic\nendogenous magnet and the promising magnetic monopole it enabled may lead to\nunconventional magnetoelectric devices and applications in the near future.",
        "positive": "Potential Energy in a Three-Dimensional Vibrated Granular Medium\n  Measured by NMR Imaging: Fast NMR imaging was used to measure the density profile of a\nthree-dimensional granular medium fluidized by vertical vibrations of the\ncontainer. For container acceleration much larger than gravity, the rise in\ncenter of mass of the granular medium is found to scale as (v0^alpha)/(N^beta)\nwith alpha = 1.0 +/-0.2 and beta = 0.5 +/- 0.1, where v0 is the vibration\nvelocity and N is the number of grains in the container. This value for alpha\nis significantly less than found previously for experiments and simulations in\none dimension (alpha = 2) and two dimensions (alpha = 1.3-1.5)."
    },
    {
        "anchor": "Dynamin recruitment by clathrin coats: a physical step?: Recent structural findings have shown that dynamin, a cytosol protein playing\na key-role in clathrin-mediated endocytosis, inserts partly within the lipid\nbilayer and tends to self-assemble around lipid tubules. Taking into account\nthese observations, we make the hypothesis that individual membrane inserted\ndynamins imprint a local cylindrical curvature to the membrane. This imprint\nmay give rise to long-range mechanical forces mediated by the elasticity of the\nmembrane. Calculating the resulting many-body interaction between a collection\nof inserted dynamins and a membrane bud, we find a regime in which the dynamins\nare elastically recruited by the bud to form a collar around its neck, which is\nreminiscent of the actual process preempting vesicle scission. This physical\nmechanism might therefore be implied in the recruitment of dynamins by clathrin\ncoats.",
        "positive": "Behavior of grains in contact with the wall of a silo during the initial\n  instants of a discharge-driven collapse: We study experimentally gravity-driven granular discharges of laboratory\nscale silos, during the initial instants of the discharge. We investigate\ndeformable wall silos around their critical collapse height, as well as rigid\nwall silos. We propose a criterion to determine a maximum time for the onset of\nthe collapse and find that the onset of collapse always occurs before the\ngrains adjacent to the wall are sliding down. We conclude that the evolution of\nthe static friction toward a state of maximum mobilization plays a crucial role\nin the collapse of the silo."
    },
    {
        "anchor": "Discriminating between individual-based models of collective cell motion\n  in a benchmark flow geometry using standardised spatiotemporal patterns: Collectively coordinated cell migration plays a role in tissue embryogenesis,\ncancer, homeostasis and healing. To study these processes, different cell-based\nmodelling approaches have been developed, ranging from lattice-based cellular\nautomata to lattice-free models that treat cells as point-like particles or\nextended detailed cell shape contours. In the spirit of what Osborne et al.\n[PLOS Computational Biology, (2017) 13, 1-34] did for cellular tissue structure\nsimulation models, we here compare five simulation models of collective cell\nmigration, chosen to be representative in increasing order of included detail.\nThey are Vicsek-Gr\\'egoire particles, Szab\\'o-like particles, self-propelled\nVoronoi model, cellular Potts model, and multiparticle cells, where each model\nincludes cell motility. We examine how these models compare when applied to the\nsame biological problem, and what differences in behaviour are due to different\nmodel assumptions and abstractions. For that purpose, we use a benchmark that\ndiscriminates between complex material flow models, and that can be\nexperimentally approached using cell cultures: the flow within a channel around\na circular obstacle, that is, the geometry Stokes used in his historical 1851\nexperiment. For each model we explain how to best implement it; vary cell\ndensity, attraction force and alignment interaction; draw the resulting maps of\nvelocity, density and deformation fields; and eventually discuss its respective\nadvantages and limitations. We thus provide a recommendation on how to select a\nmodel to answer a given question, and we examine whether models of motile\nparticles and motile cells display similar collective effects.",
        "positive": "Active colloids in liquid crystals: Active colloids in liquid crystals (ACLCs) is an active matter with\nqualitatively new facets of behavior as compared to active matter that becomes\nisotropic when relaxed into an equilibrium state. We discuss two classes of\nACLCs: (i) externally driven ACLCs, in which the motion of colloidal particles\nis powered by an externally applied electric field, and (ii) internally driven\nACLCs, formed by self-propelled particles such as bacteria. The liquid crystal\n(LC) medium is of a thermotropic type in the first case and lyotropic (water\nbased) in the second case. In the absence of external fields and self-propelled\nparticles, the ACLCs are inactive, with the equilibrium LC state exhibiting\nlong-range orientational order. The external electric field causes ACLCs of\ntype (i) to experience translations, rotations, and orbiting, powered by\nmechanisms such as LC-enabled electrokinetics, Quincke rotations and entrapment\nat the defects of LC order. A dense system of Quincke rotators, orbiting along\ncircularly shaped smectic defects, undergoes a transition into a collective\ncoherent orbiting when their activity increases. An example of internally\ndriven ACLCs of type (ii) is living liquid crystals, representing swimming\nbacteria placed in an otherwise passive lyotropic chromonic LC. The LC strongly\naffects many aspects of bacterial behavior, most notably by shaping their\ntrajectories. As the concentration of bacteria and their activity increase, the\norientational order of living liquid crystals experiences two-stage\ninstability: first, the uniform steady equilibrium director is replaced with a\nperiodic bend deformation, then, at higher activity, pairs of positive and\nnegative disclinations nucleate, separate, and annihilate in dynamic patterns\nof topological turbulence. The ACLCs are contrasted to their isotropic\ncounterparts."
    },
    {
        "anchor": "Effects of geometric confinement on a droplet between two parallel\n  planes: When a droplet (which size is characterized by R) is confined between two\nparallel planes, its morphology will change accordingly to either varying the\nvolume of the droplet or the separation (characterized by h) between the\nplanes. We are aiming at investigating how such a geometric confinement affects\nthe wetting behaviours of a droplet. Our focus lies on two distinguished\nregimes: (1) a pancake shape in a Hele-Shaw cell when the droplet is highly\ncompressed (i.e. h/R << 1), in which particular attention is paid on nonwetting\nand wetting cases, respectively; and (2) a liquid Hertzian contact rendered by\na slight confinement (i.e. h/(2R) --> 1) in a nonwetting case. To realize this\naim, we first develop strict analytical expressions of the shape of the droplet\nwhich are available for arbitrary contact angles between the liquid and the\nsolid planes, but in which the elliptic integrals indicate that these solutions\nare implicit. By employing asymptotic methods, we are able to give expressions\nof relevant geometrical and physical parameters (the Laplace pressure, droplet\nvolume, surface energy and external force) in terms of sole functions of R and\nh in an explicit manner. Comparisons suggest that over a large range of h/R,\nour asymptotic results quantitatively agree well with the numerical solutions\nof the analytical expressions. This systematic study of the parameter space\nallows a comprehensive understanding of the geometric confinement on wetting,\nespecially a wide existence of logarithmic behaviours in a liquid Hertzian\ncontact, to be identified.",
        "positive": "The Influence of Particle Softness on Active Glassy Dynamics: Active matter studies are increasingly geared towards the high-density or\nglassy limit. This is mainly inspired by the remarkable resemblance between\nactive glassy materials and conventional passive glassy matter. Interestingly,\nwithin this limit it has recently been shown that the relaxation dynamics of\nactive quasi-hard spheres is non-monotonic and most enhanced by activity when\nthe intrinsic active length scale (e.g., the persistence length) is equal to\nthe cage length, i.e. the length scale of local particle caging. This optimal\nenhancement effect is claimed to result from the most efficient scanning of\nlocal particle cages. Here we demonstrate that this effect and its physical\nexplanation are fully retained for softer active spheres. We perform extensive\nsimulations of athermal active Brownian particles (ABPs) and show that the\nnon-monotonic change of the relaxation dynamics remains qualitatively similar\nfor varying softness. We explain quantitative differences by relating them to\nthe longer range of the softer interaction potential, which decreases the cage\nlength and obscures the intrinsic active motion. Moreover, we observe that only\nwhen the persistence length surpasses the cage length, distinct qualitative\nchanges with respect to an equivalent passive Brownian particle system start to\nmanifest themselves. Overall, our results further strengthen the importance of\nthe cage length and its relation to the relevant active length scale in the\ncontext of active glassy materials."
    },
    {
        "anchor": "Analyzing Collective Motion Using Graph Fourier Analysis: Collective motion in animal groups, such as swarms of insects, flocks of\nbirds, and schools of fish, are some of the most visually striking examples of\nemergent behavior. Empirical analysis of these behaviors in experiment or\ncomputational simulation primarily involves the use of \"swarm-averaged\" metrics\nor order parameters such as velocity alignment and angular momentum. Recently,\ntools from computational topology have been applied to the analysis of swarms\nto further understand and automate the detection of fundamentally different\nswarm structures evolving in space and time. Here, we show how the field of\ngraph signal processing can be used to fuse these two approaches by\ncollectively analyzing swarm properties using graph Fourier harmonics that\nrespect the topological structure of the swarm. This graph Fourier analysis\nreveals hidden structure in a number of common swarming states and forms the\nbasis of a flexible analysis framework for collective motion.",
        "positive": "Mixing-demixing in a trapped degenerate fermion-fermion mixture: We use a time-dependent dynamical mean-field-hydrodynamic model to study\nmixing-demixing in a degenerate fermion-fermion mixture (DFFM). It is\ndemonstrated that with the increase of interspecies repulsion and/or trapping\nfrequencies, a mixed state of DFFM could turn into a fully demixed state in\nboth three-dimensional spherically-symmetric as well as quasi-one-dimensional\nconfigurations. Such a demixed state of a DFFM could be experimentally realized\nby varying an external magnetic field near a fermion-fermion Feshbach\nresonance, which will result in an increase of interspecies fermion-fermion\nrepulsion, and/or by increasing the external trap frequencies."
    },
    {
        "anchor": "Positional ordering of hard adsorbate particles in tubular nanopores: The phase behaviour and structural properties of a monolayer of hard\nparticles is examined in such a confinement, where the adsorbed particles are\nconstrained to the surface of a narrow hard cylindrical pore. The diameter of\nthe pore is chosen such that only first and second neighbour interactions occur\nbetween the hard particles. The transfer operator method of Percus and Zhang\n[Mol. Phys., 69, 347 (1990)] is reformulated to obtain information about the\nstructure of the monolayer. We have found that a true phase transition is not\npossible in the examined range of pore diameters. The monolayer of hard spheres\nundergoes a structural change from fluid-like order to a zigzag-like solid one\nwith increasing surface density. The case of hard cylinders is different in the\nsense that a layering takes place continuously between a low density one-row\nand a high density two-row monolayer. Our results reveal a clear discrepancy\nwith classical density functional theories, which do not distinguish\nsmectic-like ordering in bulk from that in narrow periodic pores.",
        "positive": "Impact of Charged Surfaces on the Structure and Dynamics of Polymer\n  Electrolytes: Insights from Atomistic Simulations: Polymer electrolytes are intensely investigated for use as solid electrolytes\nin next generation lithium-ion and lithium-metal batteries. However, little is\nknown about the structural and dynamical properties of polymer electrolytes\nclose to electrode surfaces. Here, a PEO-LiTFSI polymer electrolyte, confined\nbetween two oppositely charged graphite-like electrodes, is studied via\nmolecular dynamics simulations. Three different surface charges of $\\sigma_S =\n0$, $\\pm 0.5$ and $\\pm 1$ $e$/nm$^2$ are considered. Upon charging, a very\nstrong and component-specific layering is observed. Only for the highest\nsurface charge, lithium ions get desolvated and come into direct contact with\nthe negative electrode. The layer structure goes along with the emergence of\nfree energy barriers, which lead to a reduction of the lithium-ion dynamics, as\nquantified by spatially resolved mean square displacements, corrected for a\ndrift component. Interchain transfers that are known to be very important for\nlong-range lithium-ion transport in polymer electrolytes play no significant\nrole for transitions of lithium ions between different layers."
    },
    {
        "anchor": "Complex Dynamics of an Acoustically Levitated Fluid Droplet Captured by\n  a Low-Order Immersed Boundary Method: We present a novel immersed boundary method that implements acoustic\nperturbation theory to model an acoustically levitated droplet. Instead of\nresolving sound waves numerically, our hybrid method solves acoustic scattering\nsemi-analytically and models the corresponding time-averaged acoustic forces on\nthe droplet. This framework allows the droplet to be simulated on inertial\ntimescales of interest, and thereby admit a much larger time resolution than\ntraditional compressible flow solvers. To benchmark this technique and\ndemonstrate its utility, we implement the hybrid IBM for a single droplet in a\nstanding wave. Simulated droplet shape deformations and streaming profile agree\nwith theoretical predictions. Our simulations also yield new insights on the\nstreaming profiles for elliptical droplets, for which a comprehensive analytic\nsolution does not exist.",
        "positive": "Effect of instantaneous and continuous quenches on the density of\n  vibrational modes in model glasses: Computational studies of supercooled liquids often focus on various analyses\nof their \"underlying inherent states\" --- the glassy configurations at zero\ntemperature obtained by an infinitely-fast (instantaneous) quench from\nequilibrium supercooled states. Similar protocols are also regularly employed\nin investigations of the unjamming transition at which the rigidity of\ndecompressed soft-sphere packings is lost. Here we investigate the statistics\nand localization properties of low-frequency vibrational modes of glassy\nconfigurations obtained by such instantaneous quenches. We show that the\ndensity of vibrational modes grows as $\\omega^\\beta$ with $\\beta$ depending on\nthe parent temperature $T_{0}$ from which the glassy configurations were\ninstantaneously quenched. For quenches from high temperature liquid states we\nfind $\\beta\\!\\approx\\!3$, whereas $\\beta$ appears to approach the\npreviously-observed value $\\beta\\!=\\!4$ as $T_0$ approaches the glass\ntransition temperature. We discuss the consistency of our findings with the\ntheoretical framework of the Soft Potential Model, and contrast them with\nsimilar measurements performed on configurations obtained by continuous\nquenches at finite cooling rates. Our results suggest that any physical quench\nat rates sufficiently slower than the inverse vibrational timescale ---\nincluding all physically-realistic quenching rates of molecular or atomistic\nglasses --- would result in a glass whose density of vibrational modes is\nuniversally characterized by $\\beta\\!=\\!4$."
    },
    {
        "anchor": "Controlled Nanoparticle Formation by Diffusion Limited Coalescence: Polymeric nanoparticles (NPs) have a great application potential in science\nand technology. Their functionality strongly depends on their size. We present\na theory for the size of NPs formed by precipitation of polymers into a bad\nsolvent in the presence of a stabilizing surfactant. The analytical theory is\nbased upon diffusion-limited coalescence kinetics of the polymers.\n  Two relevant time scales, a mixing and a coalescence time, are identified and\ntheir ratio is shown to determine the final NP diameter. The size is found to\nscale in a universal manner and is predominantly sensitive to the mixing time\nand the polymer concentration if the surfactant concentration is sufficiently\nhigh. The model predictions are in good agreement with experimental data. Hence\nthe theory provides a solid framework for tailoring nanoparticles with a priori\ndetermined size.",
        "positive": "Flocking at a distance in active granular matter: The self-organised motion of vast numbers of creatures in a single direction\nis a spectacular example of emergent order. We recreate this phenomenon using\nactuated non-living components. We report here that millimetre-sized tapered\nrods, rendered motile by contact with an underlying vibrated surface and\ninteracting through a medium of spherical beads, undergo a phase transition to\na state of spontaneous alignment of velocities and orientations above a\nthreshold bead area fraction. Guided by a detailed simulation model, we\nconstruct an analytical theory of this flocking transition, with two\ningredients: a moving rod drags beads; neighbouring rods reorient in the\nresulting flow like a weathercock in the wind. Theory and experiment agree on\nthe structure of our phase diagram in the plane of rod and bead concentrations\nand power-law spatial correlations near the phase boundary. Our discovery\nsuggests possible new mechanisms for the collective transport of particulate or\ncellular matter."
    },
    {
        "anchor": "Liquid Flow Reversibly Creates a Macroscopic Surface Charge Gradient: The charging and dissolution of mineral surfaces in contact with flowing\nliquids are ubiquitous in nature, as most minerals in water spontaneously\nacquire charge and dissolve. Mineral dissolution has been studied extensively\nunder equilibrium conditions, even though non-equilibrium phenomena are\npervasive and substantially affect the mineral-water interface. Here we\ndemonstrate using interface-specific spectroscopy that liquid flow along a\ncalcium fluoride surface creates a reversible, spatial charge gradient, with\ndecreasing surface charge downstream of the flow. The surface charge gradient\ncan be quantitatively accounted for by a reaction-diffusion-advection model,\nwhich reveals that the charge gradient results from a delicate interplay\nbetween diffusion, advection, dissolution, and desorption/adsorption. The\nunderlying mechanism is expected to be valid for a wide variety of systems,\nincluding groundwater flows in nature and microfluidic systems.",
        "positive": "Contribution of internal degree of freedom of soft molecules to Soret\n  effect: We studied the Soret effect in binary dimer-monomer mixtures using\nnon-equilibrium molecular dynamics simulations and investigated the pure\ncontribution of the internal degree of freedom of flexible molecules to the\nSoret effect. We observed that the thermal diffusion factor tends to decrease\nand change its sign as the molecules become softer. We proposed two possible\nmechanisms of our observations: change of the molecule structures with the\ntemperature, causing bulkier molecules to migrate to the hotter region;\nasymmetry of the restitution between rigid and flexible molecules, due to which\nflexible molecules show larger restitution when placed at the hotter region."
    },
    {
        "anchor": "Hierarchical cross-linking in physical alginate gels: a rheological and\n  dynamic light scattering investigation: We investigate the dynamics of alginate gels, an important class of\nbiopolymer-based viscoelastic materials, by combining mechanical tests and\nnon-conventional, time-resolved light scattering methods. Two relaxation modes\nare observed upon applying a compressive or shear stress. Dynamic light\nscattering and diffusive wave spectroscopy measurements reveal that these modes\nare associated with discontinuous rearrangement events that restructure the gel\nnetwork via anomalous, non-diffusive microscopic dynamics. We show that these\ndynamics are due to both thermal activation and internal stress stored during\ngelation and propose a scenario where a hierarchy of cross-links with different\nlife times is responsible for the observed complex behavior. Measurements at\nvarious temperatures and sample ages are presented to support this scenario.",
        "positive": "Emergent helicity in free-standing semiflexible, charged polymers: Helical motifs are ubiquitious in macromolecular systems. The mechanism of\nspontaneous emergence of helicity is unknown, especially in cases where\ntorsional interactions are absent. Emergence of helical order needs coordinated\norganization over long distances in polymeric macromolecules. We establish a\nvery generic mechanism to obtain spontaneous helicity by inducing screened\nCoulomb interactions between monomers in a semiflexible heteropolymer. Due to\nchanges in solvent conditions, different segments (monomers) of a polymeric\nchain can get locally charged with charges of differing polarities and\nmagnitudes along the chain contour. This in turn leads to spontaneous emergence\nof transient helical structures along the chain contour for a wide range of\nDebye-lengths. We have avoided using torsional potentials to obtain helical\nstructures and rely only on radially symmetric interactions. Lastly, transient\nhelices can be made long-lived when they are subjected to geometric\nconfinement, which can emerge in experimental realizations through a variety of\nconditions."
    },
    {
        "anchor": "A Force-Level Theory of the Rheology of Entangled Rod and Chain Polymer\n  Liquids. II. Perturbed Reptation, Stress Overshoot, Emergent Convective\n  Constraint Release and Steady State Flow: We numerically and analytically analyze the startup continuous shear rheology\nof heavily entangled rigid rod polymer fluids based on our self-consistent,\nforce-level theory of anharmonic tube confinement. The approach is simplified\nby neglecting stress-assisted transverse barrier hopping, and irreversible\nrelaxation proceeds solely via deformation-perturbed reptation. This process is\nself-consistently coupled to tube dilation and macroscopic rheological\nresponse. We predict that with increasing strain the tube strongly dilates,\nentanglements are lost, and reptation speeds up. As a consequence, a stress\novershoot emerges not due to affine over-orientation, but rather to strong\nweakening of the entanglement network. Just beyond the stress overshoot the\nlongest relaxation time is predicted to scale as the inverse shear rate,\ncorresponding to the emergence of a generic form of convective constraint\nrelease (CCR). Its origin is a stress-induced local force that\nself-consistently couples the mesoscopic tube-scale physics with macroscopic\nmechanical response. Tube weakening at the overshoot occurs via the same\nqualitative mechanism that leads to microscopic absolute yielding in the\nnonlinear elastic scenario analyzed in the preceding paper. The stress\novershoot and emergent CCR thus correspond to an elastic-viscous crossover due\nto deformation-induced disentanglement, which at long times and high shear\nrates results in a quantitatively sensible flow stress plateau and shear\nthinning behavior. We suggest that the predicted behavior for needles is\nrelevant to flexible chain melts at low Rouse Weissenberg numbers if contour\nlength equilibration is fast. Quantitative predictions for tube dilation in the\nsteady state flow of chains melts are favorably compared to a recent\nsimulation.",
        "positive": "Gravitational Annealing of Colloidal Crystals: A silica colloidal crystal obtained by centrifugation at 9 G for 2 days in\nwater was annealed by additional stronger centrifugation at 50 G for 5 days.\nThe number of the striations observed in the colloidal crystal under crossed\npolarized light decreased at some parts in a growth container after additional\ncentrifugation, while the number alse increase at the other parts. The decrease\nprobably shows the shrinkage of the stacking disorders under high gravity,\nwhile the increase probably shows the production of new stacking disorder."
    },
    {
        "anchor": "Reply to Comment on \"Anomalous Discontinuity at the Percolation Critical\n  Point of Active Gels\": In this reply we discuss definition and estimation of the Fisher exponent in\nthe no-enclaves percolation (NEP) model.",
        "positive": "Comparison of Shear and Compression Jammed Packings of Frictional Disks: We compare the structural and mechanical properties of mechanically stable\n(MS) packings of frictional disks in two spatial dimensions (2D) generated with\nisotropic compression and simple shear protocols from discrete element modeling\n(DEM) simulations. We find that the average contact number and packing fraction\nat jamming onset are similar (with relative deviations $< 0.5\\%$) for MS\npackings generated via compression and shear. In contrast, the average stress\nanisotropy $\\langle {\\hat \\Sigma}_{xy} \\rangle = 0$ for MS packings generated\nvia isotropic compression, whereas $\\langle {\\hat \\Sigma}_{xy} \\rangle >0$ for\nMS packings generated via simple shear. To investigate the difference in the\nstress state of MS packings, we develop packing-generation protocols to first\nunjam the MS packings, remove the frictional contacts, and then rejam them.\nUsing these protocols, we are able to obtain rejammed packings with nearly\nidentical particle positions and stress anisotropy distributions compared to\nthe original jammed packings. However, we find that when we directly compare\nthe original jammed packings and rejammed ones, there are finite stress\nanisotropy deviations $\\Delta {\\hat \\Sigma}_{xy}$. The deviations are smaller\nthan the stress anisotropy fluctuations obtained by enumerating the force\nsolutions within the null space of the contact networks generated via the DEM\nsimulations. These results emphasize that even though the compression and shear\njamming protocols generate packings with the same contact networks, there can\nbe residual differences in the normal and tangential forces at each contact,\nand thus differences in the stress anisotropy."
    },
    {
        "anchor": "Soft repulsive mixtures under gravity: brazil-nut effect, depletion\n  bubbles, boundary layering, nonequilibrium shaking: A binary mixture of particles interacting via long-ranged repulsive forces is\nstudied in gravity by computer simulation and theory. The more repulsive\nA-particles create a depletion zone of less repulsive B-particles around them\nreminiscent to a bubble. Applying Archimedes' principle effectively to this\nbubble, an A-particle can be lifted in a fluid background of B-particles. This\n\"depletion bubble\" mechanism explains and predicts a brazil-nut effect where\nthe heavier A-particles float on top of the lighter B-particles. It also\nimplies an effective attraction of an A-particle towards a hard container\nbottom wall which leads to boundary layering of A-particles. Additionally, we\nhave studied a periodic inversion of gravity causing perpetual mutual\npenetration of the mixture in a slit geometry. In this nonequilibrium case of\ntime-dependent gravity, the boundary layering persists. Our results are based\non computer simulations and density functional theory of a two-dimensional\nbinary mixture of colloidal repulsive dipoles. The predicted effects also occur\nfor other long-ranged repulsive interactions and in three spatial dimensions.\nThey are therefore verifiable in settling experiments on dipolar or charged\ncolloidal mixtures as well as in charged granulates and dusty plasmas.",
        "positive": "Undulation textures at the phase transitions of some alkyloxybenzoic\n  acids: We observed undulated smectic textures for some compounds of the\n4,n-alkyloxybenzoic (nOBAC) acid series, at transitions between the smectic and\nthe isotropic phase and between the smectic and nematic phase. Studied\ncompounds were 12OBAC, 16OBAC and a binary mixture of 12- and 16OBAC. The\nundulations are dressing a usual Schlieren texture. In the case of the binary\nmixture, an interesting fingerprint pattern is observed too."
    },
    {
        "anchor": "Chain-Assisted Charge Transport in Semicrystalline Conjugated Polymers: Charge-carrier transport in a paradigmatic semicrystalline polymer\nsemiconductor (P3HT) is important for both fundamental understanding and\napplications. In samples with enhanced structural disorder due to ad-hoc point\ndefects, the mobility displays rich behavior as a function of electric field\n(F) and temperature (T). At low T, the mobility increases with the applied\nfield, but upon further increasing T, the field-dependence becomes shallower.\nEventually, at the highest T considered, the slope changes sign and the\nmobility then decreases with the field. This phenomenon can be interpreted with\nour model as a result of the competition between intrachain conductive-like\ntransport (which slows on increasing F) and interchain activated transport\n(which is faster at higher F). The former is controlling at high T where\ninterchain hops are strictly limited to nearest-neighbor monomers on adjacent\nchains. At low T, instead, interchain hops to distant sites are allowed and\ncontrol the positive correlation of the mobility with the field.",
        "positive": "Energy trapping and shock disintegration in a composite granular medium: Granular materials demonstrate a strongly nonlinear behavior influencing the\nwave propagation in the medium. We report the first experimental observation of\nimpulse energy confinement and the resultant disintegration of shock and\nsolitary waves. The medium consists of alternating ensambles of high-modulus vs\norders of magnitude lower modulus chains of different masses. The trapped\nenergy is contained within the \"softer\" portions of the composite chain and is\nslowly released in the form of weak, separated pulses over an extended period\nof time. This effect is enhanced by using a specific group assembly and\nsuperimposed force."
    },
    {
        "anchor": "Spontaneous assembly of colloidal vesicles driven by active swimmers: We explore the self-assembly process of colloidal structures immersed in\nactive baths. By considering low-valence particles we numerically investigate\nthe irreversible aggregation dynamics originated by the presence of\nrun-and-tumble swimmers. We observe the formation of long closed chains --\nvesicles -- densely filled by active swimmers. On the one hand the active bath\ndrives the self-assembly of closed colloidal structures, and on the other hand\nthe vesicles formation fosters the self-trapping of swimmers, suggesting new\nways both to build structured nanomaterials and to trap microorganisms.",
        "positive": "Dynamic behavior of elastic strips near shape transition: Elastic strips provide a canonical system for studying the mechanisms\ngoverning elastic shape transitions. Buckling, linear snap-through, and\nnonlinear snap-through have been observed in boundary-actuated strips and\nlinked to the type of bifurcation the strip undergoes at the transition. For\nnonlinear snap-through, previous work obtained the normal form at the\nbifurcation. However, to date, there is no methodology for extending this\nanalysis to other types of transition. Here, we study a set of three systems\nwhere a buckled elastic strip is actuated through rotation of its boundaries.\nDepending on the direction of rotation, the system exhibits all three types of\nshape transitions. We introduce a simple method to analyse the dynamic\ncharacteristics of an elastic structure near a transition. This method allows\nus to extend, in a straightforward manner, the asymptotic analysis proposed for\nnonlinear snap-through to the two other types of transition. We obtain the\nnormal forms of these bifurcations, and show how they dictate all the dynamic\ncharacteristics of the elastic strip. This analysis provides a profound\nunderstanding of the physical mechanisms governing elastic shape transitions\nand reliable tools to diagnose and anticipate these transitions."
    },
    {
        "anchor": "Quantum Buckling: We study the mechanical buckling of a two dimensional membrane coated with a\nthin layer of superfluid. It is seen that a singularity (vortex or anti-vortex\ndefect) in the phase of the quantum order parameter, distorts the membrane\nmetric into a negative conical singularity surface, irrespective of the defect\nsign. The defect-curvature coupling and the observed instability is in striking\ncontrast with classical elasticity where, the in-plane strain induced by\npositive (negative) disclinations is screened by a corresponding positive\n(negative) conical singularity surface. Defining a dimensionless ratio between\nsuperfluid stiffness and membrane bending modulus, we derive conditions under\nwhich the quantum buckling instability occurs. An ansatz for the resulting\nshape of the buckled membrane is analytically and numerically confirmed.",
        "positive": "Predicting Rubisco:Linker Condensation from Titration in the Dilute\n  Phase: The condensation of Rubisco holoenzymes and linker proteins into 'pyrenoids',\na crucial super-charger of photosynthesis in algae, is qualitatively understood\nin terms of 'sticker-and-spacer' theory. We derive semi-analytical partition\nsums for small Rubisco:linker aggregates, which enable the calculation of both\ndilute-phase titration curves and dimerisation diagrams. By fitting the\ntitration curves to Surface Plasmon Resonance and Single-Molecule Fluorescence\nMicroscopy data, we extract the molecular properties needed to predict\ndimerisation diagrams. We use these to estimate typical concentrations for\ncondensation, and successfully compare these to microscopy observations."
    },
    {
        "anchor": "A three-sphere microswimmer in a structured fluid: We discuss the locomotion of a three-sphere microswimmer in a viscoelastic\nstructured fluid characterized by typical length and time scales. We derive a\ngeneral expression to link the average swimming velocity to the sphere\nmobilities. In this relationship, a viscous contribution exists when the\ntime-reversal symmetry is broken, whereas an elastic contribution is present\nwhen the structural symmetry of the microswimmer is broken. As an example of a\nstructured fluid, we consider a polymer gel, which is described by a\n\"two-fluid\" model. We demonstrate in detail that the competition between the\nswimmer size and the polymer mesh size gives rise to the rich dynamics of a\nthree-sphere microswimmer.",
        "positive": "Lipid exchange enhances geometric pinning in multicomponent membranes on\n  patterned substrates: Experiments on supported lipid bilayers featuring liquid ordered/disordered\ndomains have shown that the spatial arrangement of the lipid domains and their\nchemical composition are strongly affected by the curvature of the substrate.\nFurthermore, theoretical predictions suggest that both these effects are\nintimately related with the closed topology of the bilayer. In this work, we\ntest this hypothesis by fabricating supported membranes consisting of colloidal\nparticles of various shapes lying on a flat substrate. A single lipid bilayer\ncoats both colloids and substrate, allowing local lipid exchange between them,\nthus rendering the system thermodynamically open, i.e. able to exchange heat\nand molecules with an external reservoir in the neighborhood of the colloid. By\nreconstructing the Gibbs phase diagram for this system, we demonstrate that the\nfree-energy landscape is directly influenced by the geometry of the colloid. In\naddition, we find that local lipid exchange enhances the pinning of the liquid\ndisordered phase in highly curved regions. This allows us to provide estimates\nof the bending moduli difference of the domains. Finally, by combining\nexperimental and numerical data, we forecast the outcome of possible\nexperiments on catenoidal and conical necks and show that these geometries\ncould greatly improve the precision of the current estimates of the bending\nmoduli."
    },
    {
        "anchor": "Stick slip motion in grain grain friction in a humid atmosphere: We set up an original apparatus to measure the grain grain friction stress\ninside a granular medium composed of sodo-silicate-glass beads surrounded by a\nwater vapor atmosphere.We analyze here the influence of the physico chemistry\nof water on our glass beads and its consequences on our shear experiment. We\nfound two scales in the analysis of the shear stress signal. On the microscopic\nscale of one bead, the experimental results show a dependence on the size of\nbeads, on the shear rate and on humidity for the resulting stick slip signal.\nOn the macroscopic scale of the whole assembly of beads, the behavior of the\ntotal amplitude of the shear stress depends on the size of the beads and is\nhumidity dependent only for relative humidity larger than 80%. For high degrees\nof humidity, on the microscopic scale, water lubricates the surface of the\nbeads leading to a decrease in the microscopic resistance to shear while on the\nmacroscopic scale the resistance to shear is increased: the assembly of very\nhumid grains behaves as a non Newtonian fluid.",
        "positive": "Glassy Aging with Modified Kohlrausch-Williams-Watts Form: In this report we address the question whether aging in the non equilibrium\nglassy state is controlled by the equilibrium alpha-relaxation process which\noccur at temperatures above Tg. Recently Lunkenheimer et. al. [Phys. Rev. Lett.\n95, 055702 (2005)] proposed a model for the glassy aging data of dielectric\nrelaxation using a modified Kohlrausch-Williams-Watts (KWW) form. The aging\ntime dependence of the relaxation time is defined by these authors through a\nfunctional relation involving the corresponding frequency but the stretching\nexponent is same as the alpha-relaxation stretching exponent. We present here\nan alternative functional form directly involving the relaxation time itself.\nThe proposed model fits the data of Lunkenheimer et. al. perfectly with a\nstretching exponent different from the alpha-relaxation stretching exponent."
    },
    {
        "anchor": "Hierarchical self-assembly of anisotropic colloidal platelets: Anisotropy at the level of the inter-particle interaction provides the\nparticles with specific instructions for the self-assembly of target\nstructures. The ability to synthesize non-spherical colloids, together with the\npossibility of controlling the particle bonding pattern via suitably placed\ninteraction sites, is nowadays enlarging the playfield for materials design. We\nconsider a model of anisotropic colloidal platelets with regular rhombic shape\nand two attractive sites placed along adjacent edges and we run Monte Carlo\nsimulations in two-dimensions to investigate the two-stage assembly of these\nunits into clusters with well-defined symmetries and, subsequently, into\nextended lattices. Our focus is on how the site positioning and site-site\nattraction strength can be tuned to obtain micellar aggregates that are robust\nenough to successively undergo to a second-stage assembly from sparse clusters\ninto a stable hexagonal lattice.",
        "positive": "Theoretical modeling of catalytic self-propulsion: Self-propelling particles or microswimmers have opened a new field of\ninvestigation with both fundamental and practical perspectives. They represent\nvery convenient model objects for experimental studies of active matter, and\nhave implications in nano-robotics, drug delivery, and more. Here, we summarize\nrecent advances in theoretical description of the self-propulsion of catalytic\nmicroswimmers that non-uniformly release ions, including its physical origins\nand the current switch in focus to non-linear effects, geometric tuning and\nmore. In particular, we show that the ionic self-propulsion always includes\nboth diffusiophoretic and electrophoretic contributions, and that non-linear\neffects are physical causes of a number of intriguing phenomena, such as the\nreverse in the direction of the particle motion in response to variations of\nthe salt concentration or self-propulsion of electro-neutral particles. We\nfinally suggest several remaining theoretical challenges in the field."
    },
    {
        "anchor": "Bubble kinematics in a sheared foam: We characterize the kinematics of bubbles in a sheared two-dimensional foam\nusing statistical measures. We consider the distributions of both bubble\nvelocities and displacements. The results are discussed in the context of the\nexpected behavior for a thermal system and simulations of the bubble model.\nThere is general agreement between the experiments and the simulation, but\nnotable differences in the velocity distributions point to interesting elements\nof the sheared foam not captured by prevalent models.",
        "positive": "Anomalous lateral diffusion in a viscous membrane surrounded by\n  viscoelastic media: We investigate the lateral dynamics in a purely viscous lipid membrane\nsurrounded by viscoelastic media such as polymeric solutions. We first obtain\nthe generalized frequency-dependent mobility tensor and focus on the case when\nthe solvent is sandwiched by hard walls. Due to the viscoelasticity of the\nsolvent, the mean square displacement of a disk embedded in the membrane\nexhibits an anomalous diffusion. An useful relation which connects the mean\nsquare displacement and the solvent modulus is provided. We also calculate the\ncross-correlation of the particle displacements which can be applied for\ntwo-particle tracking experiments."
    },
    {
        "anchor": "Spin-dependent magnetism and superparamagnetic contribution to the\n  magnetocaloric effect of non-stoichiometric manganite nanoparticles: Despite extensive researches on manganites owing to widespread use in modern\nelectronics, this class of metal oxides does not cease to surprise with its\nunique properties and new phenomena. Here we have studied structural and\nmagnetic properties of non-Heisenberg manganite nanoparticles with a strong\nspin-electron coupling. During transition from low temperature ferromagnetic to\nhigh temperature paramagnetic state, the change in charge, valence and spin\n(magnetic moment) with the localization of eg-electrons on the manganese ions\nhave been detected. With decrease in a temperature, the overstated effective\nmagnetic moment of Mn ions in paramagnetic phase is reduced dramatically\ntestifying to spin-dependent magnetism. The critical behavior of magnetization\nwith determination of critical parameters near second-order phase transition\nhas been studied comprehensively. Based on unusual behavior of temperature and\nfield dependences of magnetic entropy change under different magnetic field, an\nadditional influence of superparamagnetism of nanoparticles on the\nmagnetocaloric effect has been found.",
        "positive": "A closed form for the electrostatic interaction between two rod-like\n  charged objects: We have calculated the electrostatic interaction between two rod-like charged\nobjects with arbitrary orientations in three dimensions. we obtained a closed\nform formula expressing the interaction energy in terms of the separation\ndistance between the centers of the two rod-like objects, $r$, their lengths\n(denoted by $2l_1$ and $2l_2$), and their relative orientations (indicated by\n$\\theta$ and $\\phi$). When the objects have the same length ($2l_1=2l_2=l$),\nfor particular values of separations, i.e for $r\\leq0.8 l$, two types of\nminimum are appeared in the interaction energy with respect to $\\theta$. By\nemploying the closed form formula and introducing a scaled temperature $t$, we\nhave also studied the thermodynamic properties of a one dimensional system of\nrod-like charged objects. For different separation distances, the dependence of\nthe specific heat of the system to the scaled temperature has been studied. It\nis found that for $r<0.8 l$, the specific heat has a maximum."
    },
    {
        "anchor": "Solvent free model for self-assembling fluid bilayer membranes:\n  Stabilization of the fluid phase based on broad attractive tail potentials: We present a simple and highly adaptable method for simulating coarse-grained\nlipid membranes without explicit solvent. Lipids are represented by one\nhead-bead and two tail-beads, with the interaction between tails being of key\nimportance in stabilizing the fluid phase. Two such tail-tail potentials were\ntested, with the important feature in both cases being a variable range of\nattraction. We examined phase diagrams of this range versus temperature for\nboth functional forms of the tail-tail attraction and found that a certain\nthreshold attractive width was required to stabilize the fluid phase. Within\nthe fluid phase region we find that material properties such as area per lipid,\norientational order, diffusion constant, inter-leaflet flip-flop rate and\nbilayer stiffness all depend strongly and monotonically on the attractive\nwidth. For three particular values of the potential width we investigate the\ntransition between gel and fluid phases via heating or cooling and find that\nthis transition is discontinuous with considerable hysteresis. We also\ninvestigated the stretching of a bilayer to eventually form a pore and found\nexcellent agreement with a recently published analytic theory.",
        "positive": "Gaussian approximation for finitely extensible bead-spring chains with\n  hydrodynamic interaction: The Gaussian Approximation, proposed originally by Ottinger [J. Chem. Phys.,\n90 (1) : 463-473, 1989] to account for the influence of fluctuations in\nhydrodynamic interactions in Rouse chains, is adapted here to derive a new\nmean-field approximation for the FENE spring force. This \"FENE-PG\" force law\napproximately accounts for spring-force fluctuations, which are neglected in\nthe widely used FENE-P approximation. The Gaussian Approximation for\nhydrodynamic interactions is combined with the FENE-P and FENE-PG spring force\napproximations to obtain approximate models for finitely-extensible bead-spring\nchains with hydrodynamic interactions. The closed set of ODE's governing the\nevolution of the second-moments of the configurational probability distribution\nin the approximate models are used to generate predictions of rheological\nproperties in steady and unsteady shear and uniaxial extensional flows, which\nare found to be in good agreement with the exact results obtained with Brownian\ndynamics simulations. In particular, predictions of coil-stretch hysteresis are\nin quantitative agreement with simulations' results. Additional simplifying\ndiagonalization-of-normal-modes assumptions are found to lead to considerable\nsavings in computation time, without significant loss in accuracy."
    },
    {
        "anchor": "The encapsulation of hydrophobic drugs in Pluronic F127 micelles: the\n  effects of drug hydrophobicity, solution temperature and pH: Three drugs, Ibuprofen, Aspirin and Erythromycin, are encapsulated in\nspherical Pluronic F127 micelles. The shapes and the size distributions of the\nmicelles in dilute, aqueous solutions, with and without drugs, are ascertained\nusing cryo- Scanning Electron Microscopy and Dynamic Light Scattering (DLS)\nexperiments, respectively. Uptake of drugs above a threshold concentration is\nseen to reduce the critical micellization temperature of the solution. The mean\nhydrodynamic radii and polydispersities of the micelles are found to increase\nwith decrease in temperature and in the presence of drug molecules. The\nhydration of the micellar core at lower temperatures is verified using\nfluorescence measurements. Increasing solution pH leads to the ionization of\nthe drugs incorporated in the micellar cores. This causes rupture of the\nmicelles and release of the drugs into the solution at the highest solution pH\nvalue of 11.36 investigated here and is studied using DLS and fluorescence\nspectrocopy.",
        "positive": "Tagged-particle dynamics in confined colloidal liquids: We present numerical results for the tagged-particle dynamics by solving the\nmode-coupling theory in confined geometry for colloidal liquids (cMCT). We show\nthat neither the microscopic dynamics nor the type of intermediate scattering\nfunction qualitatively changes the asymptotic dynamics in vicinity of the glass\ntransition. In particular, we find similar characteristics of confinement in\nthe low-frequency susceptibility spectrum which we interpret as footprints of\nparallel relaxation. We derive predictions for the localization length and the\nscaling of the diffusion coefficient in the supercooled regime and discover a\npronounced non-monotonic dependence on the confinement length. For dilute\nliquids in the hydrodynamic limit we calculate an analytical expression for the\nintermediate scattering functions, which is in perfect agreement with\nevent-driven Brownian dynamics simulations. From this, we derive an expression\nfor persistent anti-correlations in the velocity autocorrelation function\n(VACF) for confined motion. Using numerical results of the cMCT equations for\nthe VACF we also identify a cross-over between different scalings corresponding\nto a transition from unconfined to confined behaviour."
    },
    {
        "anchor": "Low-Temperature and High-Pressure Induced Swelling of a Hydrophobic\n  Polymer-Chain in Aqueous Solution: We report molecular dynamics simulations of a hydrophobic polymer-chain in\naqueous solution between $260 {K}$ and $420 {K}$ at pressures of $1 {bar}$,\n$3000 {bar}$, and $4500 {bar}$. The simulations reveal a hydrophobically\ncollapsed state at low pressures and high temperatures. At $3000 {bar}$ and\nabout $260 {K}$ and at $4500 {bar}$ and about $260 {K}$, however, a transition\nto a swelled state is observed. The transition is driven by a smaller volume\nand a remarkably strong lower enthalpy of the swelled state, indicating a steep\npositive slope of the corresponding transition line. The swelling is stabilized\nalmost completely by the energetically favorable state of water in the polymers\nhydrophobic first hydration shell at low temperatures. Although surprising,\nthis finding is consistent with the observation of a positive heat capacity of\nhydrophobic solvation. Moreover, the slope and location of the observed\nswelling transition for the collapsed hydrophobic chain coincides remarkably\nwell with the cold denaturation transition of proteins.",
        "positive": "Giant slip length at a supercooled liquid-solid interface: The effect of temperature on friction and slip at the liquid-solid interface\nhas attracted attention over the last twenty years, both numerically and\nexperimentally. However, the role of temperature on slip close to the glass\ntransition has been less explored. Here, we use molecular dynamics to simulate\na bi-disperse atomic fluid, which can remain liquid below its melting point\n(supercooled state), to study the effect of temperature on friction and slip\nlength between the liquid and a smooth apolar wall, in a broad range of\ntemperatures. At high temperatures, an Arrhenius law fits well the temperature\ndependence of viscosity, friction and slip length. In contrast, when the fluid\nis supercooled, the viscosity becomes super-Arrhenian, while interfacial\nfriction can remain Arrhenian or even drastically decrease when lowering the\ntemperature, resulting in a massive increase of the slip length. We rationalize\nthe observed superlubricity by the surface crystallization of the fluid, and\nthe incommensurability between the structures of the fluid interfacial layer\nand of the wall. This study calls for experimental investigation of the slip\nlength of supercooled liquids on low surface energy solids."
    },
    {
        "anchor": "An approximate model for the adhesive contact of rough viscoelastic\n  surfaces: Surface roughness is known to easily suppress the adhesion of elastic\nsurfaces. Here a simple model for the contact of \\emph{viscoelastic} rough\nsurfaces with significant levels of adhesion is presented. This approach is\nderived from our previous model [E. Barthel and G. Haiat {\\em Langmuir}, 18\n9362 2002] for the adhesive contact of viscoelastic spheres. For simplicity a\nsimple loading/unloading history (infinitely fast loading and constant pull-out\nvelocity) is assumed. The model provides approximate analytical expressions for\nthe asperity response and exhibits the full viscoelastic adhesive contact\nphenomenology such as stress relaxation inside the contact zone and creep at\nthe contact edges. Combining this model with a Greenwood-Williamson statistical\nmodeling of rough surfaces, we propose a quantitative assessment of the\nadhesion to rough viscoelastic surfaces. We show that moderate viscoelasticity\nefficiently restores adhesion on rough surfaces over a wide dynamic range.",
        "positive": "Vibrational spectroscopies in liquid water: on temperature and\n  coordination effects in Raman and infrared spectroscopies: Water is an ubiquitous liquid that has several exotic and anomalous\nproperties. Despite its apparent simple chemical formula, its capability of\nforming a dynamic network of hydrogen bonds leads to a rich variety of physics.\nHere we study the vibrations of water using molecular dynamics simulations,\nmainly concentrating on the Raman and infrared spectroscopic signatures. We\ninvestigate the consequences of the temperature on the vibrational frequencies,\nand we enter the details of the hydrogen bonding coordination by using\nrestrained simulations in order to gain quantitative insight on the dependence\nof the frequencies on the neighbouring molecules. Further we consider the\ndifferences due to the different methods of solving the electronic structure to\nevaluate the forces on the ions, and report results on the angular\ncorrelations, isotopic mixtures HOD in H$_2$O/D$_2$O and and the dielectric\nconstants in water."
    },
    {
        "anchor": "Universal behavior of the apparent fragility and the structural\n  relaxation time for the high pressure previtreous effect: This report shows the universal previtreous behavior of the pressure related\napparent fragility, i.e. the steepness index Basing on this finding, the\n3-parameter relation for portraying the previtreous behavior of the primary\n(structural) relaxation time is derived. The fair portrayal of experimental\ndata was shown for glass forming 8*OCB (liquid crystal), EPON 828 (resin) and\ndiisobutyl phthalate, propylene carbonate (low molecular weight liquids). On\ndecompressing, the dynamic crossover dynamic domains is clearly detected. All\nthese recalls the mode-coupling-theory behavior, but for the pressure path. It\nis notable, the discussed description offers the fair portrayal of experimental\ndata even in the extreme pressure range P up to 2.2 GPa.",
        "positive": "Quenching of lamellar ordering in an n-alkane embedded in nanopores: We present an X-ray diffraction study of the normale alkane nonadecane\nC_{19}H_{40} embedded in nanoporous Vycor glass. The confined molecular crystal\naccomplishes a close-packed structure by alignment of the rod-like molecules\nparallel to the pore axis while sacrificing one basic principle known from the\nbulk state, i.e. the lamellar ordering of the molecules. Despite this disorder,\nthe phase transitions observed in the confined solid mimic the phase behavior\nof the 3D unconfined crystal, though enriched by the appearance of a true\nrotator phase known only from longer alkane chains."
    },
    {
        "anchor": "The dynamics of polymers in solution with hydrodynamic memory: The theory of the dynamics of polymers in solution is developed coming from\nthe hydrodynamic theory of the Brownian motion (BM) and the Rouse-Zimm (RZ)\nmodel. It is shown that the time correlation functions describing the polymer\nmotion essentially differ from those in the previous RZ models based on the\nEinstein theory of BM. The MSD of the polymer coil is at short times\nproportional to t^2 (instead of t). At long times it contains additional (to\nthe Einstein term) contributions, the leading of which is ~ t^{1/2}. The\nrelaxation of the internal normal modes of the polymer differs from the\ntraditional exponential decay. This is displayed in the tails of their\ncorrelation functions, the longest-lived being ~ t^{-3/2} in the Rouse limit\nand t^{-5/2} in the Zimm case when the hydrodynamic interaction is strong. It\nis discussed that the found peculiarities, in particular a slower diffusion of\nthe coil, should be observable in dynamic scattering experiments. The dynamic\nstructure factor and the first cumulant of the polymer coil are calculated. The\ntheory is extended to the situation when the dynamics of the studied polymer is\ninfluenced by the presence of other polymers in dilute solution.",
        "positive": "AI-assisted inverse design of sequence-ordered high intrinsic thermal\n  conductivity polymers: Artificial intelligence (AI) promotes the polymer design paradigm from a\ntraditional trial-and-error approach to a data-driven style. Achieving high\nthermal conductivity (TC) for intrinsic polymers is urgent because of their\nimportance in the thermal management of many industrial applications such as\nmicroelectronic devices and integrated circuits. In this work, we have proposed\na robust AI-assisted workflow for the inverse design of high TC polymers. By\nusing 1144 polymers with known computational TCs, we construct a surrogate deep\nneural network model for TC prediction and extract a polymer-unit library with\n32 sequences. Two state-of-the-art multi-objective optimization algorithms of\nunified non-dominated sorting genetic algorithm III (U-NSGA-III) and q-noisy\nexpected hypervolume improvement (qNEHVI) are employed for sequence-ordered\npolymer design with both high TC and synthetic possibility. For triblock\npolymer design, the result indicates that qNHEVI is capable of exploring a\ndiversity of optimal polymers at the Pareto front, but the uncertainty in\nQuasi-Monte Carlo sampling makes the trials costly. The performance of\nU-NSGA-III is affected by the initial random structures and usually falls into\na locally optimal solution, but it takes fewer attempts with lower costs. 20\nparallel U-NSGA-III runs are conducted to design the pentablock polymers with\nhigh TC, and half of the candidates among 1921 generated polymers achieve the\ntargets (TC > 0.4 W/(mK) and SA < 3.0). Ultimately, we check the TC of 50\npromising polymers through molecular dynamics simulations and reveal the\nintrinsic connections between microstructures and TCs. Our developed\nAI-assisted inverse design approach for polymers is flexible and universal, and\ncan be extended to the design of polymers with other target properties."
    },
    {
        "anchor": "The criticality of self-assembled rigid rods on triangular lattices: The criticality of self-assembled rigid rods on triangular lattices is\ninvestigated using Monte Carlo simulation. We find a continuous transition\nbetween an ordered phase, where the rods are oriented along one of the three\n(equivalent) lattice directions, and a disordered one. We conclude that\nequilibrium polydispersity of the rod lengths does not affect the critical\nbehavior, as we found that the criticality is the same as that of monodisperse\nrods on the same lattice, in contrast with the results of recently published\nwork on similar models.",
        "positive": "A Data-Driven Statistical Description for the Hydrodynamics of Active\n  Matter: Modeling living systems at the collective scale can be very challenging\nbecause the individual constituents can themselves be complex and the\nrespective interactions between the constituents are not fully understood. With\nthe advent of high throughput experiments and in the age of big data,\ndata-driven methods are on the rise to overcome these challenges. To directly\nuncover the underlying physical principles, we present a data-driven method for\nobtaining the phase-space density such that the solution to the stochastic\ndynamic equation for active matter readily emerges, from which time and space\ndependence of physical order parameters can be readily extracted. If the system\nis near a steady state, we illuminate how to construct a field theory to\nsubsequently make physical predictions about the system. The method is first\ndeveloped analytically and subsequently calibrated using simulated data. The\nmethod is then applied to an experimental system of particles actively driven\nby a {\\it Serratia marcescens} bacterial swarm and in the presence of spatially\nlocalized UV light. The analysis demonstrates that the particles are in the\nsteady-state before and sometime after the UV light and obey a Gaussian field\ntheory with a spatially-varying \"mass\" in those regimes. This novel, yet\nsimple, finding is surprising given the complex dynamics of the bacterial\nswarm. In response to the UV light, we demonstrate that there is a net flow of\nthe particles away from the UV light and that the entropy of the particles\nincreases away from the light. We conclude with a discussion of additional\npotential applications of our data-driven method such as when the internal\nstructure of the individual constituents dynamically changes to result in a\nmodified stochastic dynamic equation governing the system."
    },
    {
        "anchor": "Dense random packing with a power-law size distribution: the structure\n  factor, mass-radius relation, and pair distribution function: We consider dense random packing of disks with a power-law distribution of\nradii and investigate their correlation properties. We study the corresponding\nstructure factor, mass-radius relation and pair distribution function of the\ndisk centers. A toy model of dense segments in one dimension (1d) is solved\nexactly. It is shown theoretically in 1d and numerically in 1d and 2d that such\npacking exhibits fractal properties. It is found that the exponent of the\npower-law distribution and the fractal dimension coincide. An approximate\nrelation for the structure factor in arbitrary dimension is derived, which can\nbe used as a fitting formula in small-angle scattering. The findings can be\nuseful for understanding microstructural properties of various systems like\nultra-high performance concrete, high-internal-phase ratio emulsions or\nbiological systems.",
        "positive": "Transfer Free Energies and Partitioning of Small Molecules in Collapsed\n  PNIPAM Polymers: A central quantity in the design of functional hydrogels used as nanocarrier\nsystems, for instance for drug delivery or adaptive nanocatalysis, is the\npartition ratio, which quantifies the uptake of a molecular substance by the\npolymer matrix. By employing all-atom molecular dynamics simulations, we study\nthe solvation and partitioning (with respect to bulk water) of small\nsubnanometer-sized solutes in a dense matrix of collapsed\nPoly(N-isopropylacrylamide) (PNIPAM) polymers above the lower critical solution\ntemperature (LCST) in aqueous solution. We examine the roles of the solute's\npolarity and its size on the solubility properties in the thermoresponsive\npolymer. We show that the transfer free energies of nonpolar solutes from bulk\nwater into the polymer are favorable and scale in a good approximation with the\nsolute's surface area. Even for small solute size variation, partitioning can\nvary over orders of magnitude. A polar nature of the solute, on the other hand,\ngenerally opposes the transfer, at least for alkyl solutes. Finally, we find a\nstrong correlation between the transfer free energies in the gel and the\nadsorption free energies on a single extended polymer chain, which enables us\nto relate the partition ratios in the swollen and collapsed state of a PNIPAM\ngel."
    },
    {
        "anchor": "Modeling the large-scale structure of a barchan dune field: In nature, barchan dunes typically exist as members of larger fields that\ndisplay striking, enigmatic structures that cannot be readily explained by\nexamining the dynamics at the scale of single dunes, or by appealing to\npatterns in external forcing. To explore the possibility that observed\nstructures emerge spontaneously as a collective result of many dunes\ninteracting with each other, we built a numerical model that treats barchans as\ndiscrete entities that interact with one another according to simplified rules\nderived from theoretical and numerical work and from field observations: (1)\nDunes exchange sand through the fluxes that leak from the downwind side of each\ndune and are captured on their upstream sides; (2) when dunes become\nsufficiently large, small dunes are born on their downwind sides (`calving');\nand (3) when dunes collide directly enough, they merge. Results show that these\nrelatively simple interactions provide potential explanations for a range of\nfield-scale phenomena including isolated patches of dunes and heterogeneous\narrangements of similarly sized dunes in denser fields. The results also\nsuggest that (1) dune field characteristics depend on the sand flux fed into\nthe upwind boundary, although (2) moving downwind, the system approaches a\ncommon attracting state in which the memory of the upwind conditions vanishes.\nThis work supports the hypothesis that calving exerts a first-order control on\nfield-scale phenomena; it prevents individual dunes from growing without bound,\nas single-dune analyses suggest, and allows the formation of roughly realistic,\npersistent dune field patterns.",
        "positive": "The Behavior of Cyclohexane Confined in Slit Carbon Nanopore: It is well known that confining a liquid into a pore strongly alters the\nliquid behavior. Investigations of the effect of confinement are of great\nimportance for many scientific and technological applications. Here we present\na molecular dynamics study of the behavior of cyclohexane confined in carbon\nslit pores. The local structure and orientational ordering of cyclohexane\nmolecules are investigated. It is shown that the system freezes with decreasing\nthe pore width, and the freezing temperature of nanoconfined cyclohenae is\nhigher than the bulk one."
    },
    {
        "anchor": "Dynamics of Low Anisotropy Morphologies in Directional Solidification: We report experimental results on quasi-two-dimensional diffusion limited\ngrowth in directionally solidified succinonitrile with small amounts of\npoly(ethylene oxide), acetone, or camphor as a solute. Seaweed growth, or dense\nbranching morphology, is selected by growing grains close to the $\\{111\\}$\nplane, where the in-plane surface tension is nearly isotropic. The observed\ngrowth morphologies are very sensitive to small anisotropies in surface tension\ncaused by misorientations from the $\\{111\\}$ plane. Different seaweed\nmorphologies are found, including the degenerate, the stabilized, and the\nstrongly tilted seaweeds. The degenerate seaweeds show a limited fractal\nscaling range and, with increased undercooling, suggests a transition from\n\"fractal\" to \"compact\" seaweed. Strongly tilted seaweeds demonstrate a\nsignificant twofold anisotropy. In addition, seaweed-dendrite transitions are\nobserved in low anisotropy growth.",
        "positive": "Spectral method for the time-dependent Gross-Pitaevskii equation with a\n  harmonic trap: We study the numerical resolution of the time-dependent Gross-Pitaevskii\nequation, a non-linear Schroedinger equation used to simulate the dynamics of\nBose-Einstein condensates. Considering condensates trapped in harmonic\npotentials, we present an efficient algorithm by making use of a spectral\nGalerkin method, using a basis set of harmonic oscillator functions, and the\nGauss-Hermite quadrature. We apply this algorithm to the simulation of\ncondensate breathing and scissors modes."
    },
    {
        "anchor": "Salt parameterization can drastically affect the results from classical\n  atomistic simulations of water desalination by MoS$_2$ nanopores: Water scarcity is a reality in our world, and scenarios predicted by leading\nscientists in this area indicate that it will worsen in the next decades.\nHowever, new technologies based in low-cost seawater desalination can prevent\nthe worst scenarios, providing fresh water for humanity. With this goal,\nmembranes based in nanoporous materials have been suggested in recent years.\nOne of the materials suggested is MoS$_2$, and classical Molecular Dynamics\n(MD) simulation is one of the most powerful tools to explore these\nnanomaterials. However, distinct Force Fields employed in MD simulations are\nparameterized based on distinct experimental quantities. In this paper, we\ncompare two models of salt that were build based on distinct properties of\nwater-salt mixtures. One model fits the hydration free energy and lattice\nproperties, the second fits the crystal density and the density and the\ndielectric constant of water and salt mixtures. To compare the models, MD\nsimulations for salty water flow through two nanopores sizes were used -- one\npore big enough to accommodate hydrated ions, and one smaller in which the ion\nhas to dehydrate to enter, and two rigid water models from the TIP4P family --\nthe TIP4P/2005 and TIP4P/$\\epsilon$. Our results indicate that the water\npermeability and salt rejection by the membrane are more influenced by the salt\nmodel than by the water model, especially for the narrow pore. In fact,\ncompletely distinct mechanisms were observed, and they are related to the\ncharacteristics employed in the ion model parameterization. The results show\nthat not only the water model can influence the outcomes, but the ion model\nplays a crucial role.",
        "positive": "Lateral pressure profile in lipid membranes with finite curvature and\n  mechanosensitive channel gating: This review describes the analytical calculation of lateral pressure profile\nin lipid membrane with finite curvature. The derivation is based on the\npreviously developed microscopic model of flexible strings [1,2]. According to\nthis theory the energy per unit chain is considered as energy of flexible\nstring (Euler's elastic beam of finite thickness) and interaction between\nchains is considered as an entropic repulsion. This microscopic theory allows\nto obtain expression for lateral pressure distribution in bent lipid membrane\nif treating a bending as a small deviation from the flat membrane conformation\nand using perturbation theory with small parameter L0J, where L0 is the\nmonolayer thickness, J is mean curvature of membrane. Because lateral pressure\ndistribution is related to the elastic properties of lipid bilayer [3] then\nfirst spontaneous moment of lateral pressure and the expression for bending\nmodulus may be derived from this theoretical model. Finally, based on\nanalytical expression for the lateral pressure distribution in bent lipid\nmembrane one can obtain analytically the energy difference between two states\nof mechanosensitive channel, particularly MscL [4, 5, 6]. Calculated expression\ndepends on inter-facial surface tension, the channel area change in region\nbetween hydrophobic interior and the aqueous surroundings and the bending\nmodulus and spontaneous bending moment values."
    },
    {
        "anchor": "Matched asymptotic solutions for the steady banded flow of the diffusive\n  Johnson-Segalman model in various geometries: We present analytic solutions for steady flow of the Johnson-Segalman (JS)\nmodel with a diffusion term in various geometries and under controlled strain\nrate conditions, using matched asymptotic expansions. The diffusion term\nrepresents a singular perturbation that lifts the continuous degeneracy of\nstable, banded, steady states present in the absence of diffusion. We show that\nthe stable steady flow solutions in Poiseuille and cylindrical Couette\ngeometries always have two bands. For Couette flow and small curvature, two\ndifferent banded solutions are possible, differing by the spatial sequence of\nthe two bands.",
        "positive": "Swinging Motion of Active Deformable Particles in Poiseuille Flow: Dynamics of active deformable particles in an external Poiseuille flow is\ninvestigated. In order to make the analysis general, we employ time-evolution\nequations derived from symmetry considerations that take into account an\nelliptical shape deformation. First, we clarify the relation of our model to\nthat of rigid active particles. Then, we study the dynamical modes that active\ndeformable particles exhibit by changing the strength of the external flow. We\nemphasize the difference between the active particles that tend to self-propel\nparallel to the elliptical shape deformation and those self-propelling\nperpendicularly. In particular, a swinging motion around the centerline far\nfrom the channel walls is discussed in detail."
    },
    {
        "anchor": "Onset of anomalous diffusion in colloids confined to quasi-monolayers: It has been recently shown that a colloidal monolayer, e.g., formed at a\nfluid interface or by means of a suitable confining potential, exhibits\nanomalous collective diffusion. This is a consequence of the hydrodynamic\ninteractions mediated by the three-dimensional (3D) ambient fluid when the\nparticles are confined to reside on a two-dimensional (2D) manifold. We study\ntheoretically and with numerical simulations the crossover from normal to\nanomalous diffusion as the particles are, in real systems, confined by a 3D\nexternal potential and thus have the possibility to fluctuate out of the 2D\nmanifold, thus forming actually a quasi-monolayer.",
        "positive": "Influence of the backward propagating waves on the threshold in planar\n  nematic liquid crystal films: We analyze theoretically the influence of backward propagating waves on the\nprimary threshold when a linearly polarized light impinges at normal incidence\non a planarly aligned nematic liquid crystal films. We show, that the primary\nthreshold, as a function of the phase delay induced by the nematic layer,\nexhibits oscillations. The amplitude of oscillations depends strongly on the\ndrop of the refractivity indices of the nematic and outer media at the\nboundaries."
    },
    {
        "anchor": "A Brownian Dynamics Model of Kinesin in Three Dimensions Incorporating\n  the Force-Extension Profile of the Coiled-Coil Cargo Tether: The Kinesin family of motor proteins are involved in a variety of cellular\nprocesses that transport materials and generate force. With recent advances in\nexperimental techniques, such as optical tweezers which can probe individual\nmolecules, there has been an increasing interest in understanding the\nmechanisms by which motor proteins convert chemical energy into mechanical\nwork. Here we present a mathematical model for the chemistry and three\ndimensional mechanics of the Kinesin motor protein which captures many of the\nforce dependent features of the motor. For the elasticity of the tether that\nattaches cargo to the motor we develop a method for deriving the non-linear\nforce-extension relationship from optical trap data. For the Kinesin heads,\ncargo, and microscope stage we formulate a three dimensional Brownian Dynamics\nmodel that takes into account excluded volume interactions. To efficiently\ncompute statistics from the model an algorithm is proposed that uses a two step\nprotocol that separates the simulation of the mechanical features of the model\nfrom the chemical kinetics of the model. Using this approach for a bead\ntransported by the motor, the force dependent average velocity and randomness\nparameter are computed and compared with the experimental data.",
        "positive": "The stability limit of polydisperse sticky hard spheres: It has been shown by Stell [J. Stat. Phys. 63, 1203 (1991)] that at low\ntemperature monodisperse sticky spheres collapse to form coexisting\nclose-packed solid and infinitely dilute gases. We show that polydisperse\nsticky spheres also collapse and calculate the collapse temperature. The\npolydisperse spheres separate into fractions with narrower polydispersities\nwhich can then solidify. This is the first example of a single-peaked\npolydisperse mixture phase separating. It implies that a mixture of\npolydisperse large hard spheres with much smaller hard spheres does not show\nfluid--fluid coexistence."
    },
    {
        "anchor": "Structural fluctuations and quantum transport through DNA molecular\n  wires: a combined molecular dynamics and model Hamiltonian approach: Charge transport through a short DNA oligomer (Dickerson dodecamer) in\npresence of structural fluctuations is investigated using a hybrid\ncomputational methodology based on a combination of quantum mechanical\nelectronic structure calculations and classical molecular dynamics simulations\nwith a model Hamiltonian approach. Based on a fragment orbital description, the\nDNA electronic structure can be coarse-grained in a very efficient way. The\ninfluence of dynamical fluctuations arising either from the solvent\nfluctuations or from base-pair vibrational modes can be taken into account in a\nstraightforward way through time series of the effective DNA electronic\nparameters, evaluated at snapshots along the MD trajectory. We show that charge\ntransport can be promoted through the coupling to solvent fluctuations, which\ngate the onsite energies along the DNA wire.",
        "positive": "Smectic-$A$ elastomers with weak director anchoring: Experimentally it is possible to manipulate the director in a (chiral)\nsmectic-$A$ elastomer using an electric field. This suggests that the director\nis not necessarily locked to the layer normal, as described in earlier papers\nthat extended rubber elasticity theory to smectics. Here, we consider the case\nthat the director is weakly anchored to the layer normal assuming that there is\na free energy penalty associated with relative tilt between the two. We use a\nrecently developed weak-anchoring generalization of rubber elastic approaches\nto smectic elastomers and study shearing in the plane of the layers, stretching\nin the plane of the layers, and compression and elongation parallel to the\nlayer normal. We calculate, inter alia, the engineering stress and the tilt\nangle between director and layer normal as functions of the applied\ndeformation. For the latter three deformations, our results predict the\nexistence of an instability towards the development of shear accompanied by\nsmectic-$C$-like order."
    },
    {
        "anchor": "Simulating nanoscale dielectric response: We introduce a constrained energy functional to describe dielectric response.\nWe demonstrate that the local functional is a generalization of the long ranged\nMarcus energy. Our re-formulation is used to implement a cluster Monte Carlo\nalgorithm for the simulation of dielectric media. The algorithm avoids solving\nthe Poisson equation and remains efficient in the presence of spatial\nheterogeneity, nonlinearity and scale dependent dielectric properties.",
        "positive": "A discrete model of water with two distinct glassy phases: We investigate a minimal model for non-crystalline water, defined on a Husimi\nlattice. The peculiar random-regular nature of the lattice is meant to account\nfor the formation of a random 4-coordinated hydrogen-bond network. The model\nturns out to be consistent with most thermodynamic anomalies observed in liquid\nand supercooled-liquid water. Furthermore, the model exhibits two glassy phases\nwith different densities, which can coexist at a first-order transition. The\nonset of a complex free-energy landscape, characterized by an exponentially\nlarge number of metastable minima, is pointed out by the cavity method, at the\nlevel of 1-step replica symmetry breaking."
    },
    {
        "anchor": "Statistical mechanics of two-dimensional foams: Physical foundations of\n  the model: In a recent series of papers [1--3], a statistical model that accounts for\ncorrelations between topological and geometrical properties of a\ntwo-dimensional shuffled foam has been proposed and compared with experimental\nand numerical data. Here, the various assumptions on which the model is based\nare exposed and justified: the equiprobability hypothesis of the foam\nconfigurations is argued. The range of correlations between bubbles is\ndiscussed, and the mean field approximation that is used in the model is\ndetailed. The two self-consistency equations associated with this mean field\ndescription can be interpreted as the conservation laws of number of sides and\nbubble curvature, respectively. Finally, the use of a '' Grand-Canonical ''\ndescription, in which the foam constitutes a reservoir of sides and curvature,\nis justified.",
        "positive": "The intertwined roles of particle shape and surface roughness in\n  controlling the shear strength of a granular material: Both the shape of individual particles and their surface properties\ncontribute to the strength of a granular material under shear. Here we show the\ndegree to which these two aspects can be intertwined. In experiments on\nassemblies of 3D printed, convex lens-shaped particles, we measure the\nstress-strain response under repeated compressive loading and find that the\naggregate's shear strength falls rapidly when compared to other particle\nshapes. We probe the granular material at mm-scales with X-ray computed\ntomography and $\\mu$m-scales with high-resolution surface metrology to look for\nthe cause of the degradation. We find that wear due to accumulated deformation\nsmooths out the lens surfaces in a controlled and systematic manner that\ncorrelates with a significant loss of shear strength observed for the assembly\nas a whole. The sensitivity of lenses to changes in surface properties\ncontrasts with results for assemblies of 3D printed tetrahedra and spheres,\nwhich under the same load cycling are found to exhibit only minor degradation\nin strength. This case study provides insight into the relationship between\nparticle shape, surface wear, and the overall material response, and suggests\nnew strategies when designing a granular material with desired evolution of\nproperties under repeated deformation."
    },
    {
        "anchor": "Alignment of colloidal rods in crowded environments: Understanding the hydrodynamic alignment of colloidal rods in polymer\nsolutions is pivotal for manufacturing structurally ordered materials. How\npolymer crowding influences the flow-induced alignment of suspended colloidal\nrods remains unclear when rods and polymers share similar length-scales. We\ntackle this problem by analyzing the alignment of colloidal rods suspended in\ncrowded polymer solutions, and comparing against the case where crowding is\nprovided by additional colloidal rods in a pure solvent. We find that the\npolymer dynamics govern the onset of shear-induced alignment of colloidal rods\nsuspended in polymer solutions, and the control parameter for the alignment of\nrods is the Weissenberg number, quantifying the elastic response of the polymer\nto an imposed flow. Moreover, we show that the increasing colloidal alignment\nwith the shear rate follows a universal trend that is independent of the\nsurrounding crowding environment. Our results indicate that colloidal rod\nalignment in polymer solutions can be predicted based on the critical shear\nrate at which polymer coils are deformed by the flow, aiding the synthesis and\ndesign of anisotropic materials.",
        "positive": "Elastic shakedown and roughness evolution in repeated elastic-plastic\n  contact: Surface roughness emerges naturally during mechanical removal of material,\nfracture, chemical deposition, plastic deformation, indentation, and other\nprocesses. Here, we use continuum simulations to show how roughness which is\nneither Gaussian nor self-affine emerges from repeated elastic-plastic contact\nof rough and rigid surfaces on a flat elastic-plastic substrate. Roughness\nprofiles change with each contact cycle, but appear to approach a steady-state\nlong before the substrate stops deforming plastically and has hence\n\"shaken-down\" elastically. We propose a simple dynamic collapse for the\nemerging power-spectral density, which shows that the multi-scale nature of the\nroughness is encoded in the first few indentations. In contrast to macroscopic\nroughness parameters, roughness at small scales and the skewness of the height\ndistribution of the resulting roughness do not show a steady-state, with the\nlatter vanishing asymptotically with contact cycle."
    },
    {
        "anchor": "Steady shear magnetorheology in Co0.9Ni0.1 nanocluster-based MR fluids\n  at elevated temperatures: In this paper, we present the study of magnetorheological properties of\nmagnetic fluids containing Co0.9Ni0.1 nanocluster that have been measured as a\nfunction of both magnetic field and temperature. Co-rich nanoclusters were\nsynthesized by conventional homogeneous nucleation in liquid polyol.\nMorphological characterization using FESEM revealed the non-aggregated nature\nof nanoclusters with an average diameter of 450 nm. Crystal structure and room\ntemperature magnetization measurements were performed by powder XRD and\nvibrating sample magnetometry (VSM). Two MR samples of different particle\nvolume fractions were prepared. Temperature-dependent steady shear MR\ncharacterizations for both the samples in the range of 250C-550C demonstrated\nsystematic decline of MR parameters with increasing temperatures. The\ntemperature-induced thinning of shear stress and viscosity was explained in\nterms of change in effective volume fraction and magnetic saturation. To\nanalyze the measured variation in MR response with increasing temperature,\nsuitable temperature-sensitive scaling parameters were also constructed.\nFinally to generalize the trend, rheological master curves were constructed by\nusing time-temperature-field superposition method.",
        "positive": "Swelling kinetics of the onion phase: A theory is presented for the behavior of an array of multi-lamellar vesicles\n(the onion phase) upon addition of solvent. A unique feature of this system is\nthe possibility to sustain pressure gradients by tension in the lamellae.\nTension enables the onions to remain stable beyond the unbinding point of a\nflat lamellar stack. The model accounts for various concentration profiles and\ninterfaces developing in the onion as it swells. In particular, densely packed\n`onion cores' are shown to appear, as observed in experiments. The formation of\ninterfaces and onion cores may represent an unusual example of stabilization of\ncurved interfaces in confined geometry."
    },
    {
        "anchor": "A model for the generic alpha relaxation of viscous liquids: Dielectric measurements on molecular liquids just above the glass transition\nindicate that alpha relaxation is characterized by a generic high-frequency\nloss varying as $\\omega^{-1/2}$, whereas deviations from this come from one or\nmore low-lying beta processes [Olsen et al, Phys. Rev. Lett. {\\bf 86} (2001)\n1271]. Assuming that long-wavelength fluctuations dominate the dynamics, a\nmodel for the dielectric alpha relaxation based on the simplest coupling\nbetween the density and dipole density fields is proposed here. The model,\nwhich is solved in second order perturbation theory in the Gaussian\napproximation, reproduces the generic features of alpha relaxation.",
        "positive": "Ion-sensitive phase transitions driven by Debye-H\u00fcckel non-ideality: We find that the Debye-H\\\"uckel nonideality of dilute aqueous electrolytes is\nsufficient to drive volume phase transitions and criticality, even in the\nabsence of a self-attracting or elastic network. Our result follows from a\nLandau mean-field theory for a system of confined ions in an external solution\nof mixed-valence counterions, where the ratio of squared monovalent to divalent\nion concentration provides a temperature-like variable for the phase\ntransition. Our analysis was motivated by long-studied volume phase transitions\nvia ion exchange in ionic gels, but our findings agree with existing theory for\nvolume-temperature phase transitions in charged hard-sphere models and other\nsystems by Fisher and Levin, and McGahay and Tomozawa. Our mean-field model\npredicts a continuous line of gas-liquid-type critical points connecting a\npurely monovalent, divalent-sensitive critical point at one extreme with a\ndivalent, monovalent-sensitive critical point at the other; an alternative\nrepresentation of the Landau functional handles this second limit. It follows\nthat critical sensitivity to ion valence is tunable to any desired valence\nratio. The critical or discontinuous dependent variable can be the confinement\nvolume; alternatively the internal electrical potential may be more convenient\nin applications. Our simplified conditions for ionic phase transitions to\noccur, together with our relatively simple theory to describe them, may\nfacilitate exploration of tunable critical sensitivity in areas such as ion\ndetection technology, biological switches and osmotic control."
    },
    {
        "anchor": "Strong deformation of ferrofluid-filled elastic alginate capsules in\n  inhomogenous magnetic fields: We present a new system based on alginate gels for the encapsulation of a\nferrofluid drop, which allows us to create millimeter-sized elastic capsules\nthat are highly deformable by inhomogeneous magnetic fields. We use a\ncombination of experimental and theoretical work in order to characterize and\nquantify the deformation behavior of these ferrofluid-filled capsules. We\nintroduce a novel method for the direct encapsulation of unpolar liquids by\nsodium alginate. The addition of polar alcohol molecules allows us to\nencapsulate a ferrofluid as a single phase. This encapsulation method increases\nthe amount of encapsulated magnetic nanoparticles resulting in high\ndeformations and offers possible applications of capsules as actuators,\nswitches, or valves in confined spaces like microfluidic devices. We determine\nboth elastic moduli of the capsule shell, Young's modulus and Poisson's ratio,\nby employing two independent mechanical methods, spinning capsule measurements\nand capsule compression between parallel plates. We then show that the observed\nmagnetic deformation can be fully understood from magnetic forces exerted by\nthe ferrofluid on the capsule shell if the magnetic field distribution and\nmagnetization properties of the ferrofluid are known. Using an iterative\nsolution scheme that couples a finite element / boundary element method for the\nmagnetic field calculation to the solution of the elastic shape equations, we\nachieve quantitative agreement between theory and experiment for deformed\ncapsule shapes using the Young modulus from mechanical characterization and the\nsurface Poisson ratio as a fit parameter. This detailed analysis confirms the\nresults from mechanical characterization that the surface Poisson ratio of the\nalginate shell is close to unity, that is, deformations of the alginate shell\nare almost area conserving.",
        "positive": "Energy production rates in fluid mixtures of inelastic rough hard\n  spheres: The aim of this work is to explore the combined effect of polydispersity and\nroughness on the partial energy production rates and on the total cooling rate\nof a granular fluid mixture. We consider a mixture of inelastic rough hard\nspheres of different number densities, masses, diameters, moments of inertia,\nand mutual coefficients of normal and tangential restitution. Starting from the\nfirst equation of the BBGKY hierarchy, the collisional energy production rates\nassociated with the translational and rotational temperatures ($T_i^\\text{tr}$\nand $T_i^\\text{rot}$) are expressed in terms of two-body average values. Next,\nthose average values are estimated by assuming a velocity distribution function\nbased on maximum-entropy arguments, allowing us to express the energy\nproduction rates and the total cooling rate in terms of the partial\ntemperatures and the parameters of the mixture. Finally, the results are\napplied to the homogeneous cooling state of a binary mixture and the influence\nof inelasticity and roughness on the temperature ratios\n$T_1^\\text{tr}/T_1^\\text{rot}$, $T_2^\\text{tr}/T_1^\\text{tr}$, and\n$T_2^\\text{rot}/T_1^\\text{rot}$ is analyzed."
    },
    {
        "anchor": "Phase behavior and mesoscale solubilization in aqueous solutions of\n  hydrotropes: Hydrotropes are amphiphilic molecules that are too small to spontaneously\nform equilibrium structures in aqueous solutions, but form dynamic, noncovalent\nassemblies, referred to as clusters. In the presence of a hydrophobic compound,\nthese clusters seem to get stabilized leading to the formation of long-lived,\nhighly stable mesoscopic droplets, a phenomenon that we call mesoscale\nsolubilization. In this work, we focus on the unusual mesoscopic properties of\naqueous solutions of a nonionic hydrotrope, namely tertiary butyl alcohol\n(TBA), on addition of various hydrophobic compounds. Aqueous TBA solutions, in\nabout 3 to 8 mol percent TBA concentration range and about 0 to 25 deg. C\ntemperature range, show the presence of short-ranged (0.5 nm), short-lived\n(tens of picoseconds) molecular clusters which result in anomalies of the\nthermodynamic properties. These clusters are transient but do not relax by\ndiffusion, thus distinctly different from conventional concentration\nfluctuations. In this concentration and temperature range, upon the addition of\na third (more hydrophobic) component to TBA-water solutions, long-lived\nmesoscopic droplets of about 100 nm size are observed. In this work, we clarify\nthe ambiguity behind the definition of solubility and elucidate the phenomenon\nof mesoscale solubilization. A systematic study of the macro and meso phase\nbehavior of three ternary systems TBA-water-propylene oxide, TBA-water-isobutyl\nalcohol, and TBA-water-cyclohexane has been carried out. We differentiate\nbetween molecular solubility, mesoscale solubilization, and macroscopic phase\nseparation. We have confirmed that practically stable aqueous colloids can be\ncreated from small molecules, without addition of surfactants or polymers. Such\nkind of novel materials may find applications in the design of various\nprocesses and products, ranging from pharmaceuticals to cosmetics and\nagrochemicals.",
        "positive": "Thrust force is tuned by the rigidity distribution in insect-inspired\n  flapping wings: We study the aerodynamics of a flapping flexible wing with a two-vein pattern\nthat mimics the elastic response of insect wings in a simplified manner. The\nexperiments reveal a non-monotonic variation of the thrust force produced by\nthe wings when the angle between the two veins is varied. An optimal\nconfiguration is consistently reached when the two veins are spaced at an angle\nof about 20 degrees. This value is in the range of what has been measured in\nthe literature for several insect species. The deformation of the wings is\nmonitored during the experiment using video recordings, which allows to\npinpoint the physical mechanism behind the non-monotonic behaviour of the force\ncurve and the optimal distribution of the vein network in terms of propulsive\nforce."
    },
    {
        "anchor": "Dipole fluid as a basic model for the equation of state of ionic liquid\n  in the vicinity of their critical point: The model of dipole fluid for the ionic liquids similar to the molten NaCl is\nproposed. The estimates for the critical parameters are obtained with the help\nof the van der Waals equation of state. The influence of the rotation on the\ncharacteristics of a dipole pair and the location of the critical point is\ndiscussed. The dissociation of such fluid near the critical point is\nconsidered.",
        "positive": "Determination of Interaction Potentials of Amino Acids from Native\n  Protein Structures: Test on Simple Lattice Models: We propose a novel method for the determination of the effective interaction\npotential between the amino acids of a protein. The strategy is based on the\ncombination of a new optimization procedure and a geometrical argument, which\nalso uncovers the shortcomings of any optimization procedure. The strategy can\nbe applied on any data set of native structures such as those available from\nthe Protein Data Bank (PDB). In this work, however, we explain and test our\napproach on simple lattice models, where the true interactions are known a\npriori. Excellent agreement is obtained between the extracted and the true\npotentials even for modest numbers of protein structures in the PDB.\nComparisons with other methods are also discussed."
    },
    {
        "anchor": "Active prestress leads to an apparent stiffening of cells through\n  geometrical effects: Tuning of active prestress e.g. through activity of molecular motors\nconstitutes a powerful cellular tool to adjust cellular stiffness through\nnonlinear material properties. Understanding this tool is an important\nprerequisite for our comprehension of cellular force response, cell shape\ndynamics and tissue organisation. Experimental data obtained from\ncell-mechanical measurements often show a simple linear dependence between\nmechanical prestress and measured differential elastic moduli. While these\nexperimental findings could point to stress-induced structural changes in the\nmaterial, we propose here a surprisingly simple alternative explanation in a\ntheoretical study. We show how geometrical effects can give rise to increased\ncellular force response of cells in the presence of active prestress. The\nassociated effective stress-stiffening is disconnected from actual\nstress-induced changes of the elastic modulus and should therefore be regarded\nas an apparent stiffening of the material. We argue that new approaches in\nexperimental design are necessary to separate this apparent stress-stiffening\ndue to geometrical effects from actual nonlinearities of the elastic modulus in\nprestressed cellular material.",
        "positive": "Phase separation kinetics of binary mixture in the influence of bond\n  disorder: Sensitivity to quench temperature: Morphologies in phase separating systems can significantly influence the\nfinal properties of materials. We present extensive Monte Carlo (MC) simulation\nresults on the segregation kinetics of the critical binary (AB) mixture with a\nfraction of bond disorder (BD) introduced in a regular manner. We focus on\nstudying the effect of various quench temperatures on the growth kinetics and\nscaling properties of evolving morphologies. The two-dimensional (2d) kinetic\nIsing system with conserved spin exchange kinetics is used to model the system.\nWe observe that domain morphologies change from their usual interconnected\nbicontinuous isotropic patterns at zero BD to short strips and lamellar\npatterns (anisotropy) with increasing BD at shallow quench. The domain\nevolution remains extremely slow at deep quench and for lower fractions of BD,\nand thus, morphologies appear very similar; however, we observed lamellar\npatterns at high BD. The scaling behavior represented by the correlation\nfunction and the structure factor changes significantly with quench depths for\na higher fraction of BD. In contrast, a tiny deviation from the scaling is\nobserved at a lower fraction of disorder for shallow quenches. The growth law\nis consistent with the Lifshitz-Slyozov (LS) growth law (\\phi->1/3) for shallow\nquench and at low fractions of BD studied here. At a high fraction of BD, the\nlength scale crossovers gradually from an early time LS growth to the diffusion\ndynamics (\\phi->1/2) during intermediate times for both deep and shallow\nquenches. The domain growth freezes (\\phi->0) to a finite size when the system\nevolves to an equilibrium (stable) lamellar morphology in the asymptotic time\nlimit on the time scale of our simulation. However, no significant changes are\nobserved in the scaling behavior at lower fractions of BD for the deep quench."
    },
    {
        "anchor": "Finite-size corrections for confined polymers in the extended de Gennes\n  regime: Theoretical results for the extension of a polymer confined to a channel are\nusually derived in the limit of infinite contour length. But experimental\nstudies and simulations of DNA molecules confined to nanochannels are not\nnecessarily in this asymptotic limit. We calculate the statistics of the span\nand the end-to-end distance of a semiflexible polymer of finite length in the\nextended de Gennes regime, exploiting the fact that the problem can be mapped\nto a one-dimensional weakly self-avoiding random walk. The results thus\nobtained compare favourably with pruned-enriched Rosenbluth method (PERM)\nsimulations of a three-dimensional discrete wormlike chain model of DNA\nconfined in a nanochannel. We discuss the implications for experimental studies\nof linear $\\lambda$-DNA confined to nanochannels at the high ionic strengths\nused in many experiments.",
        "positive": "Bubble Growth Rate in Superheated Droplets: Calculations are presented to describe the dynamic of a growing bubble in a\nsingle and simple formulation for R(t). The calculations show clearly that the\nbehavior of the growing bubble is exponentially increasing with the time\nconstant {\\tau} showing a universal behavior as a function of the reduced\nsuperheat. Experimental data from other researchers are used to verify the\ndescription and are in good agreement with the results. The main motivation for\nthis study was to find R(t)that is accurate and at the same time uncomplicated\nenough in solving the dynamic of the bubble growth to calculate the far-field\npressure for superheated liquids."
    },
    {
        "anchor": "The building blocks of dynamical heterogeneities in dense granular media: We investigate experimentally the connection between short time dynamics and\nlong time dynamical heterogeneities within a dense granular media under cyclic\nshear. We show that dynamical heterogeneities result from a two timescales\nprocess. Short time but already collective events consisting in clustered cage\njumps concentrate most of the non affine displacements. On larger timescales\nsuch clusters appear aggregated both temporally and spatially in avalanches\nwhich eventually build the large scales dynamical heterogeneities. Our results\nindicate that facilitation plays an important role in the relaxation process\nalthough it does not appear to be conserved as proposed in many models studied\nin the literature.",
        "positive": "Cerium oxide catalyzed disproportionation of hydrogen peroxide: a closer\n  look at the reaction intermediate: Cerium oxide nanoparticles (CNPs) have recently gained increasing interest as\nredox enzyme-mimetics to scavenge the intracellular excess of reactive oxygen\nspecies, including hydrogen peroxide (H2O2). Despite the extensive exploration\nof CNP scavenging activity, there remains a notable knowledge gap regarding the\nfundamental mechanism underlying the CNP catalyzed disproportionation of H2O2.\nIn this Letter, we present evidence demonstrating that H2O2 adsorption at CNP\nsurface triggers the formation of stable intermediates known as ceriumperoxo\ncomplexes (Ce-O2 2-). The cerium-peroxo complexes can be resolved by Raman\nscattering and UV-Visible spectroscopy. We further demonstrate that the\ncatalytic reactivity of CNPs in the H2O2 disproportionation reaction increases\nwith the Ce(III) fraction. The developed approach using UV-Visible spectroscopy\nfor the characterization of Ce-O2 2-complexes can potentially serve as a\nfoundation for determining the catalytic reactivity of CNPs in the\ndisproportionation of H2O2."
    },
    {
        "anchor": "Hydrodynamic shocks in microroller suspensions: We combine experiments, large scale simulations and continuum models to study\nthe emergence of coherent structures in a suspension of magnetically driven\nmicrorollers sedimented near a floor. Collective hydrodynamic effects are\npredominant in this system, leading to strong density-velocity coupling. We\ncharacterize a uniform suspension and show that density waves propagate freely\nin all directions in a dispersive fashion. When sharp density gradients are\nintroduced in the suspension, we observe the formation of a shock. Unlike\nBurgers' shock-like structures observed in other active and driven confined\nhydrodynamic systems, the shock front in our system has a well-defined finite\nwidth and moves rapidly compared to the mean suspension velocity. We introduce\na continuum model demonstrating that the finite width of the front is due to\nfar-field nonlocal hydrodynamic interactions and governed by a geometric\nparameter: the average particle height above the floor.",
        "positive": "Water-mediated ordering of nanoparticles in electric field: Interfacial polar molecules feature a strongly anisotropic response to\napplied electric field, favoring dipole orientations parallel to the interface.\nIn water, in particular, this effect combines with generic orientational\npreferences induced by spatial asymmetry of water hydrogen bonding under\nconfined geometry, which may give rise to a Janus interface. The two effects\nmanifest themselves in considerable dependence of water polarization on both\nthe field direction relative to the interface, and the polarity (sign) of the\nfield. Using molecular simulations, we demonstrate strong field-induced\norientational forces acting on apolar surfaces through water mediation. At a\nfield strength comparable to electric fields around a DNA polyion, the torques\nwe predict to act on an adjacent nanoparticle are sufficient to overcome\nthermal fluctuations. These torques can align a particle with surface as small\nas 1 nm2. The mechanism can support electrically controlled ordering of\nsuspended nanoparticles as a means of tuning their properties, and can find\napplication in electro-nanomechanical devices."
    },
    {
        "anchor": "Necklace-Cloverleaf Transition in Associating RNA-like Diblock\n  Copolymers: We consider a ${\\rm A}_m{\\rm B}_n$ diblock copolymer, whose links are capable\nof forming local reversible bonds with each other. We assume that the resulting\nstructure of the bonds is RNA--like, i.e. topologically isomorphic to a tree.\nWe show that, depending on the relative strengths of A--A, A--B and B--B\ncontacts, such a polymer can be in one of two different states. Namely, if a\nself--association is preferable (i.e., A--A and B--B bonds are comparatively\nstronger than A--B contacts) then the polymer forms a typical randomly branched\ncloverleaf structure. On the contrary, if alternating association is preferable\n(i.e. A--B bonds are stronger than A--A and B--B contacts) then the polymer\ntends to form a generally linear necklace structure (with, probably, some rear\nside branches and loops, which do not influence the overall characteristics of\nthe chain). The transition between cloverleaf and necklace states is studied in\ndetails and it is shown that it is a 2nd order phase transition.",
        "positive": "Yield Stress Fluids Solidifying in Capillary Imbibition: When subjected to an external stress that exceeds the yield stress\n($\\sigma_\\mathrm{Y}$), yield stress fluids (YSFs) undergo a solid-to-liquid\ntransition. Despite the extensive studies, there has been limited attention to\nthe process of liquid-to-solid transition. This work examines the\nsolidification of YSFs through capillary imbibition, easily observed in the\nprocesses of wetting, coating, spreading, and wicking. During gradual\ndeceleration of the capillary rise, YSFs display an unexpected flowing\nbehavior, even when subjected to stresses below the $\\sigma_\\mathrm{Y}$. We\npropose a model with numerical solutions based on rheological properties of\nYSFs and slip to capture this unusual, yet universal behavior."
    },
    {
        "anchor": "Orientational instability of the director in a nematic cell caused by\n  electro-induced anchoring modification: We theoretically investigate the threshold for the director reorientation\nfrom the homeotropic state to the hybrid homeotropic-planar state and vice\nversa in a cell filled with a flexoelectric nematic liquid crystal (NLC)\nsubjected to an electric field. The liquid crystal is doped by a CTAB-like\nsubstance, a part of molecules of which dissociates into positive and negative\nions. The anchoring on one of the cell surfaces is assumed to be strong and\nhomeotropic, while the other surface can adsorb positive ions which play the\nrole of an orienting surfactant for NLC molecules on this surface. At certain\nvoltages, the orientational transitions in the bulk of the NLC are possible due\nto the changing conditions for the director on the adsorbing surface. We\ncalculate respective threshold voltages as functions of anchoring parameters.\nThe existence of the critical values of these parameters, beyond which the\norientational transitions do not take place, is established.",
        "positive": "Dynamics of active liquid interfaces: Controlling interfaces of phase separating fluid mixtures is key to creating\ndiverse functional soft materials. Traditionally, this is accomplished with\nsurface-modifying chemical agents. Using experiment and theory, we study how\nmechanical activity shapes soft interfaces that separate an active and a\npassive fluid. Chaotic flows in the active fluid give rise to giant interfacial\nfluctuations and non-inertial propagating active waves. At high activities,\nstresses disrupt interface continuity and drive droplet generation, producing\nan emulsion-like active state comprised of finite-sized droplets. When in\ncontact with a solid boundary, active interfaces exhibit non-equilibrium\nwetting transitions, wherein the fluid climbs the wall against gravity. These\nresults demonstrate the promise of mechanically driven interfaces for creating\na new class of soft active matter."
    },
    {
        "anchor": "Self-Induced Rayleigh-Taylor Instability in Segregating Dry Granular\n  Flows: Dry granular material flowing on rough inclines can experience a self-induced\nRayleigh-Taylor (RT) instability followed by the spontaneous emergence of\nconvection cells. For this to happen, particles are different in size and\ndensity, the larger particles are the denser but still segregate toward the\nsurface. When the flow is, as usual, initially made of two layers, dense\nparticles above, a Rayleigh-Taylor instability develops during the flow. When\nthe flow is initially made of one homogeneous layer mixture, the granular\nsegregation leads to the formation of an unstable layer of large-dense\nparticles at the surface which subsequently destabilizes in a RT plume pattern.\nThe unstable density gradient has been only induced by the motion of the\ngranular matter. This self-induced Rayleigh-Taylor instability and the\ntwo-layer RT instability are studied using two different methods, experiments\nand simulations. At last, contrarily to the usual fluid behavior where the RT\ninstability relaxes into two superimposed stable layers of fluid, the granular\nflow evolves to a pattern of alternated bands corresponing to recirculation\ncells analogous to Rayleigh-B{\\'e}nard convection cells where segregation\nsustains the convective motion.",
        "positive": "The Frequency Response Function of the Creep Compliance: Motivated from the need to convert time-dependent rheometry data into complex\nfrequency response functions, this paper studies the frequency response\nfunction of the creep compliance that is coined the complex creep function.\nWhile for any physically realizable viscoelastic model the Fourier transform of\nthe creep compliance diverges in the classical sense, the paper shows that the\ncomplex creep function, in spite of exhibiting strong singularities, it can be\nconstructed with the calculus of generalized functions. The mathematical\nexpressions of the real and imaginary parts of the Fourier transform of the\ncreep compliance of simple rheological networks derived in this paper are shown\nto be Hilbert pairs; therefore, returning back in the time domain a causal\ncreep compliance. The paper proceeds by showing how a measured creep compliance\nof a solid-like or a fluid-like viscoelastic material can be decomposed into\nelementary functions with parameters that can be identified from best fit of\nexperimental data. The proposed technique allows for a direct determination of\nthe parameters of the corresponding viscoelastic models and leads to dependable\nexpressions of their complex-frequency response functions."
    },
    {
        "anchor": "Density-Temperature-Softness Scaling of the Dynamics of Glass-forming\n  Soft-sphere Liquids: The principle of dynamic equivalence between soft-sphere and hard-sphere\nfluids [Phys. Rev. E \\textbf{68}, 011405 (2003)] is employed to describe the\ninterplay of the effects of varying the density n, the temperature T, and the\nsoftness (characterized by a softness parameter {\\nu}^{-1}) on the dynamics of\nglass-forming soft-sphere liquids in terms of simple scaling rules. The main\nprediction is that the dynamic parameters of these systems, such as the\n{\\alpha}-relaxation time and the long-time self-diffusion coefficient, depend\non n, T, and {\\nu} only through the reduced density n^\\ast \\equiv\nn{\\sigma}^{3}_{HS}(T, {\\nu}),where the effective hard-sphere diameter\n{\\sigma}_{HS}(T, {\\nu}) is determined, for example, by the\nAndersen-Weeks-Chandler condition for soft-sphere-hard-sphere structural\nequivalence. A number of scaling properties observed in recent simulations\ninvolving glass-forming fluids with repulsive short range interactions are\nfound to be a direct manifestation of this general dynamic equivalence\nprinciple. The self-consistent generalized Langevin equation (SCGLE) theory of\ncolloid dynamics is shown to accurately capture these scaling rules",
        "positive": "Morphology of Nematic and Smectic Vesicles: Recent experiments on vesicles formed from block copolymers with\nliquid-crystalline side-chains reveal a rich variety of vesicle morphologies.\nThe additional internal order (\"structure\") developed by these self-assembled\nblock copolymer vesicles can lead to significantly deformed vesicles as a\nresult of the delicate interplay between two-dimensional ordering and vesicle\nshape. The inevitable topological defects in structured vesicles of spherical\ntopology also play an essential role in controlling the final vesicle\nmorphology. Here we develop a minimal theoretical model for the morphology of\nthe membrane structure with internal nematic/smectic order. Using both analytic\nand numerical approaches, we show that the possible low free energy\nmorphologies include nano-size cylindrical micelles (nano-fibers), faceted\ntetrahedral vesicles, and ellipsoidal vesicles, as well as cylindrical\nvesicles. The tetrahedral vesicle is a particularly fascinating example of a\nfaceted liquid-crystalline membrane. Faceted liquid vesicles may lead to the\ndesign of supra-molecular structures with tetrahedral symmetry and new classes\nof nano-carriers."
    },
    {
        "anchor": "Synchronization and Collective Dynamics in a Carpet of Microfluidic\n  Rotors: We study synchronization of an array of rotors on a substrate that are\ncoupled by hydrodynamic interaction. The rotors that are modeled by an\neffective rigid body, are driven by an internal torque and exerts an active\nforce on the surrounding fluid. The long-ranged nature of the hydrodynamic\ninteraction between the rotors causes a rich pattern of dynamical behaviors\nincluding phase ordering and turbulent spiral waves. The model provides a novel\nexample of coupled oscillators with long-range interaction. Our results suggest\nstrategies for designing controllable microfluidic mixers using the emergent\nbehavior of hydrodynamically coupled active components.",
        "positive": "A Thermal Resistance Network Model for Heat Conduction of Amorphous\n  Polymers: Thermal conductivities (TCs) of the vast majority of amorphous polymers are\nin a very narrow range, 0.1 $\\sim$ 0.5 Wm$^{-1}$K$^{-1}$, although single\npolymer chains possess TC of orders-of-magnitude higher. Entanglement of\npolymer chains plays an important role in determining the TC of bulk polymers.\nWe propose a thermal resistance network (TRN) model for TC in amorphous\npolymers taking into account the entanglement of molecular chains. Our model\nexplains well the physical origin of universally low TC observed in amorphous\npolymers. The empirical formulae of pressure and temperature dependence of TC\ncan be successfully reproduced from our model not only in solid polymers but\nalso in polymer melts. We further quantitatively explain the anisotropic TC in\noriented polymers."
    },
    {
        "anchor": "Probing temperature-responsivity of microgels and its interplay with a\n  solid surface by superresolution microscopy and numerical simulations: Superresolution microscopy has become a powerful tool to investigate the\ninternal structure of complex colloidal and polymeric systems, such as\nmicrogels, at the nanometer scale. The ability to monitor microgels response to\ntemperature changes in situ opens new and exciting opportunities to design and\nprecisely control their behaviour for various applications. When performing\nadvanced microscopy experiments, interactions between the particle and the\nenvironment can be important. Often microgels are deposited on a substrate\nsince they have to remain still for several minutes during the experiment. This\nstudy uses dSTORM microscopy and advanced coarse-grained molecular dynamics\nsimulations to investigate, for the first time, how individual microgels\nanchored on hydrophilic and hydrophobic surfaces undergo their volume phase\ntransition in temperature. We find that, in the presence of a hydrophilic\nsubstrate, the structure of the microgel is unperturbed and the resulting\ndensity profiles quantitatively agree with simulations performed in bulk\nconditions. Instead, when a hydrophobic surface is used, the microgel spreads\nat the interface and an interesting competition between the two hydrophobic\nstrengths -- monomer-monomer vs monomer-surface -- comes into play at high\ntemperatures. The remarkable agreement between experiments and simulations\nmakes the present study a fundamental step to establish this high-resolution\nmonitoring technique as a platform for investigating more complex systems,\nbeing these either macromolecules with peculiar internal structure or\nnanocomplexes where molecules of interest can be encapsulated in the microgel\nnetwork and controllably released with temperature.",
        "positive": "Surface Kinetics and Generation of Different Terms in a Conservative\n  Growth Equation: A method based on the kinetics of adatoms on a growing surface under\nepitaxial growth at low temperature in (1+1) dimensions is proposed to obtain a\nclosed form of local growth equation. It can be generalized to any growth\nproblem as long as diffusion of adatoms govern the surface morphology. The\nmethod can be easily extended to higher dimensions. The kinetic processes\ncontributing to various terms in the growth equation (GE) are identified from\nthe analysis of in-plane and downward hops. In particular, processes\ncorresponding to the (h -> -h) symmetry breaking term and curvature dependent\nterm are discussed. Consequence of these terms on the stable and unstable\ntransition in (1+1) dimensions is analyzed. In (2+1) dimensions it is shown\nthat an additional (h -> -h) symmetry breaking term is generated due to the\nin-plane curvature associated with the mound like structures. This term is\nindependent of any diffusion barrier differences between in-plane and out\nof-plane migration. It is argued that terms generated in the presence of\ndownward hops are the relevant terms in a GE. Growth equation in the closed\nform is obtained for various growth models introduced to capture most of the\nprocesses in experimental Molecular Beam Epitaxial growth. Effect of\ndissociation is also considered and is seen to have stabilizing effect on the\ngrowth. It is shown that for uphill current the GE approach fails to describe\nthe growth since a given GE is not valid over the entire substrate."
    },
    {
        "anchor": "Prescribed pattern transformation in swelling gel tubes by elastic\n  instability: We present a study on swelling-induced circumferential buckling of tubular\nshaped gels. Inhomogeneous stress develops as gel swells under mechanical\nconstraints, which gives rise to spontaneous buckling instability without\nexternal force. Full control over the post-buckling pattern is experimentally\ndemonstrated. A simple analytical model is developed using elastic energy to\npredict stability and post-buckling patterns upon swelling. Analysis reveals\nthat height to diameter ratio is the most critical design parameter to\ndetermine buckling pattern, which agrees well with experimental and numerical\nresults.",
        "positive": "Dressed Counterions: Strong Electrostatic Coupling in the Presence of\n  Salt: We reformulate the theory of strong electrostatic coupling in order to\ndescribe an asymmetric electrolyte solution of monovalent salt ions and\npolyvalent counterions using field-theoretical techniques and Monte-Carlo\nsimulations. The theory is based on an asymmetric treatment of the different\ncomponents of the electrolyte solution. The weak coupling Debye-Huckel approach\nis used in order to describe the monovalent salt ions while a strong coupling\napproach is used to tackle the polyvalent counterions. This combined\nweak-strong coupling approach effectively leads to dressed interactions between\npolyvalent counterions and thus directly affects the correlation attraction\nmediated by polyvalent counterions between like-charged objects. The general\ntheory is specifically applied to a system composed of two uniformly charged\nplane-parallel surfaces in the presence of salt and polyvalent counterions. In\nthe strong coupling limit for polyvalent counterions the comparison with\nMonte-Carlo simulations shows good agreement for large enough values of the\nelectrostatic coupling parameter. We delineate two limiting laws that in fact\nencompass all the Monte-Carlo data."
    },
    {
        "anchor": "Radial fingering in a Hele-Shaw cell: a weakly nonlinear analysis: The Saffman-Taylor viscous fingering instability occurs when a less viscous\nfluid displaces a more viscous one between narrowly spaced parallel plates in a\nHele-Shaw cell. Experiments in radial flow geometry form fan-like patterns, in\nwhich fingers of different lengths compete, spread and split. Our weakly\nnonlinear analysis of the instability predicts these phenomena, which are\nbeyond the scope of linear stability theory. Finger competition arises through\nenhanced growth of sub-harmonic perturbations, while spreading and splitting\noccur through the growth of harmonic modes. Nonlinear mode-coupling enhances\nthe growth of these perturbations with appropriate relative phases, as we\ndemonstrate through a symmetry analysis of the mode coupling equations. We\ncontrast mode coupling in radial flow with rectangular flow geometry.",
        "positive": "Effective Interactions and Volume Energies in Charged Colloids: Linear\n  Response Theory: Interparticle interactions in charge-stabilized colloidal suspensions, of\narbitrary salt concentration, are described at the level of effective\ninteractions in an equivalent one-component system. Integrating out from the\npartition function the degrees of freedom of all microions, and assuming linear\nresponse to the macroion charges, general expressions are obtained for both an\neffective electrostatic pair interaction and an associated microion volume\nenergy. For macroions with hard-sphere cores, the effective interaction is of\nthe DLVO screened-Coulomb form, but with a modified screening constant that\nincorporates excluded volume effects. The volume energy -- a natural\nconsequence of the one-component reduction -- contributes to the total free\nenergy and can significantly influence thermodynamic properties in the limit of\nlow-salt concentration. As illustrations, the osmotic pressure and bulk modulus\nare computed and compared with recent experimental measurements for deionized\nsuspensions. For macroions of sufficient charge and concentration, it is shown\nthat the counterions can act to soften or destabilize colloidal crystals."
    },
    {
        "anchor": "Universal Scaling of Wave Propagation Failure in Arrays of Coupled\n  Nonlinear Cells: We study the onset of the propagation failure of wave fronts in systems of\ncoupled cells. We introduce a new method to analyze the scaling of the critical\nexternal field at which fronts cease to propagate, as a function of\nintercellular coupling. We find the universal scaling of the field throughout\nthe range of couplings, and show that the field becomes exponentially small for\nlarge couplings. Our method is generic and applicable to a wide class of\ncellular dynamics in chemical, biological, and engineering systems. We confirm\nour results by direct numerical simulations.",
        "positive": "Discontinuous liquid rise in capillaries with nonuniform cross-sections: We consider theoretically liquid rise against gravity in capillaries with\nheight-dependent cross-section. For a conical capillary made from a hydrophobic\nsurface and dipped in a liquid reservoir, the equilibrium liquid height depends\non the cone opening angle $\\alpha$, the Young-Dupr\\'{e} contact angle $\\theta$,\nthe cone radius at the reservoir's level $R_0$ and the capillary length\n$\\kappa^{-1}$. As $\\alpha$ is increased from zero, the meniscus' position\nchanges continuously until, when $\\alpha$ attains a critical value, the\nmeniscus jumps to the bottom of the capillary. For hydrophilic surfaces the\nmeniscus jumps to the top. The same liquid height discontinuuity can be\nachieved with electrowetting with no mechanical motion. Essentially the same\nbehavior is found for two tilted surfaces. We further consider capillaries with\nperiodic radius modulations, and find that there are few competing minima for\nthe meniscus location. A transition from one to another can be performed by the\nuse of electrowetting. The phenomenon discussed here may find uses in\nmicrofluidic applications requiring the transport small amounts of water\n``quanta'' (volume$<1$ nL) in a regular fashion."
    },
    {
        "anchor": "A variational approach to the liquid-vapor phase transition for hardcore\n  ions in the bulk and in nanopores: We employ a field-theoretical variational approach to study the behavior of\nionic solutions in the grand canonical ensemble. To describe properly the\nhardcore interactions between ions, we use a cutoff in Fourier space for the\nelectrostatic contribution of the grand potential and the Carnahan-Starling\nequation of state with a modified chemical potential for the pressure one. We\nfirst calibrate our method by comparing its predictions at room temperature\nwith Monte Carlo results for excess chemical potential and energy. We then\nvalidate our approach in the bulk phase by describing the classical \"ionic\nliquid-vapor\" phase transition induced by ionic correlations at low\ntemperature, before applying it to electrolytes at room temperature confined to\nnanopores embedded in a low dielectric medium and coupled to an external\nreservoir of ions. The ionic concentration in the nanopore is then correctly\ndescribed from very low bulk concentrations, where dielectric exclusion shifts\nthe transition up to room temperature for sufficiently tight nanopores, to high\nconcentrations where hardcore interactions dominate which, as expected, modify\nonly slightly this ionic \"capillary evaporation\".",
        "positive": "Dilute dispersion of compound particles: deformation dynamics and\n  rheology: Compound particles are a class of composite systems in which solid particles\nencapsulated in a fluid droplet are suspended in another fluid. They are\nencountered in various natural and biological processes, for e.g., nucleated\ncells, hydrogels, microcapsules etc. In this work, we analyze the flow in and\naround a concentric compound particle and investigate the deformation and\nreorientation dynamics of the confining drop and its stability against breakup\nin imposed linear flows. We obtain analytical expressions for the flow fields\nupto O(Ca) (capillary number) and the deformed shape of the confining drop upto\nO(Ca^2) using a domain perturbation technique. Further, we develop an O(Ca)\nconstitutive equation for the volume-averaged stress for a dilute dispersion of\ncompound particles. Compared to linear theory, O(Ca^2) calculations are found\nto be important as they make qualitatively different predictions in some linear\nflows. We find that the strong hydrodynamic interaction between the\nencapsulated particle and the confining interface results in an increased\ndeformation of the confining drop compared to that of a simple drop, and\nenhances the rheological quantities such as the effective shear viscosity,\nextensional viscosity, and normal stress differences in a dilute dispersion.\nThese measures pertaining to particles, drops, and particles coated with a\nfluid film are also derived as limiting cases of compound particles. Moreover,\nlinear viscoelastic behavior of a dilute dispersion of compound particles is\ncharacterized in terms of complex modulus by subjecting the dispersion to a\nsmall amplitude oscillatory shear flow."
    },
    {
        "anchor": "Molecular Structure and Multi-Body Potential of Mean Force in\n  Silica-Polystyrene Nanocomposites: We perform a systematic application of the hybrid particle-field molecular\ndynamics technique [Milano et al, J. Chem. Phys. 2009, 130, 214106] to study\ninterfacial properties and potential of mean force (PMF) for separating\nnanoparticles (NPs) in a melt. Specifically, we consider Silica NPs bare or\ngrafted with Polystyrene chains, aiming to shed light on the interactions among\nfree and grafted chains affecting the dispersion of NPs in the nanocomposite.\nThe proposed hybrid models show good performances in catching the local\nstructure of the chains, and in particular their density profiles, documenting\nthe existence of the \"wet-brush-to-dry-brush\" transition. By using these\nmodels, the PMF between pairs of ungrafted and grafted NPs in Polystyrene\nmatrix are calculated. Moreover, we estimate the three-particle contribution to\nthe total PMF and its role in regulating the phase separation on the nanometer\nscale. In particular, the multi-particle contribution to the PMF is able to\ngive an explanation of the complex experimental morphologies observed at low\ngrafting densities. More in general, we propose this approach and the models\nutilized here for a molecular understanding of specific systems and the impact\nof the chemical nature of the systems on the composite final properties.",
        "positive": "The Maxwell crossover and the van der Waals equation of state: The well-known Maxwell construction[1] (the equal-area rule, EAR) was devised\nfor vapor liquid equilibrium (VLE) calculation with the van der Waals (vdW)\nequation of state (EoS)[2]. The EAR generates an intermediate volume between\nthe saturated liquid and vapor volumes. The trajectory of the intermediate\nvolume over the coexistence region is defined here as the Maxwell crossover,\ndenoted as the M-line, which is independent of EoS. For the vdW or any cubic[3]\nEoS, the intermediate volume corresponds to the unphysical root, while other\ntwo corresponding to the saturated volumes of vapor and liquid phases,\nrespectively. Due to its unphysical nature, the intermediate volume has always\nbeen discarded. Here we show that the M-line, which turns out to be strictly\nrelated to the diameter[4] of the coexistence curve, holds the key to solving\nseveral major issues. Traditionally the coexistence curve with two branches is\nconsidered as the extension of the Widom line[5,6-9]. This assertion causes an\ninconsistency in three planes of temperature, pressure and volume. It is found\nthat the M-line is the natural extension of the Widom line into the\nvapor-liquid coexistence region. As a result, the united single line coherently\ndivides the entire phase space, including the coexistence and supercritical\nfluid regions, into gas-like and liquid-like regimes in all the planes.\nMoreover, along the M-line the vdW EoS finds a new perspective to access the\nsecond-order transition in a way better aligning with observations and modern\ntheory[10]. Lastly, by using the feature of the M-line, we are able to derive a\nhighly accurate and analytical proximate solution to the VLE problem with the\nvdW EoS."
    },
    {
        "anchor": "Chiral ground states of ferroelectric liquid crystals: Ferroelectric nematic liquid crystals are formed by achiral molecules with\nlarge dipole moments. Its three-dimensional orientational order is universally\ndescribed as unidirectionally polar. We demonstrate that the ground state of\nferroelectric nematic unconstrained by externally imposed alignment directions\nis chiral, with left- and right-hand twists of polarization. Although the\nhelicoidal deformations and defect walls separating domains of opposite\nhandedness increase the elastic energy, the twists reduce the electrostatic\nenergy and become weaker when the material is doped with ions. The study shows\nthat the polar orientational order of molecules could trigger chirality in the\nsoft matter with no chemically induced chiral centers.",
        "positive": "Capacitive energy storage in single-file pores: Exactly-solvable models\n  and simulations: Understanding charge storage in low-dimensional electrodes is crucial for\ndeveloping novel ecologically friendly devices for capacitive energy storage\nand conversion, water desalination, etc. Exactly-solvable models allow in-depth\nanalyses and essential physical insights into the charging mechanisms. So far,\nhowever, such analytical approaches have been mainly limited to lattice models.\nHerein, we develop a versatile, exactly-solvable, one-dimensional off-lattice\nmodel for charging single-file pores. Unlike the lattice model, this model\nshows an excellent quantitative agreement with three-dimensional Monte Carlo\nsimulations. With analytical calculations and simulations, we show that the\ndifferential capacitance can be bell-shaped (one peak), camel-shaped (two\npeaks), or have four peaks. Transformations between these capacitance shapes\ncan be induced by changing pore ionophilicity, cation-anion size asymmetry, or\nby adding solvent. We find that the camel-shaped capacitance, characteristic of\ndilute electrolytes, appears for strongly ionophilic pores with high ion\ndensities, which we relate to charging mechanisms specific to narrow pores. We\nalso derive a large-voltage asymptotic expression for the capacitance, showing\nthat the capacitance decays to zero as the inverse square of the voltage, $C\n\\sim u^{-2}$. This dependence follows from hard-core interactions and is not\ncaptured by the lattice model."
    },
    {
        "anchor": "Continuum modeling of mechanically-induced creep in dense granular\n  materials: Recently, a new nonlocal granular rheology was successfully used to predict\nsteady granular flows, including grain-size-dependent shear features, in a wide\nvariety of flow configurations, including all variations of the split-bottom\ncell. A related problem in granular flow is that of mechanically-induced creep,\nin which shear deformation in one region of a granular medium fluidizes its\nentirety, including regions far from the sheared zone, effectively erasing the\nyield condition everywhere. This enables creep deformation when a force is\napplied in the nominally quiescent region through an intruder such as a\ncylindrical or spherical probe. We show that the nonlocal fluidity model is\ncapable of capturing this phenomenology. Specifically, we explore creep of a\ncircular intruder in a two-dimensional annular Couette cell and show that the\nmodel captures all salient features observed in experiments, including both the\nrate-independent nature of creep for sufficiently slow driving rates and the\nfaster-than-linear increase in the creep speed with the force applied to the\nintruder.",
        "positive": "Molecular simulation of thermosetting polymer hardening: reactive events\n  enabled by controlled topology transfer: We present a quantum mechanical / molecular mechanics (QM/MM) to tackle\nchemical reactions with substantial molecular reorganization. For this,\nmolecular dynamics simulations with smoothly switched interaction models are\nused to suggest suitable product states, whilst a Monte Carlo algorithm is\nemployed to assess the reaction likeliness subject to energetic feasibility. As\na demonstrator, we study the cross-linking of bisphenol F diglycidyl ether\n(BFDGE) and 4,6-diethyl-2-methylbenzene-1,3-diamine (DETDA). The modeling of\nepoxy curing was supplemented by Differential Scanning Calorimetry (DSC)\nmeasurements, which confirms the degrees of cross-linking as a function of\ncuring temperature. Likewise, the heat of formation and the mechanical\nproperties of the resulting thermosetting polymer are found to be in good\nagreement with previous experiments."
    },
    {
        "anchor": "The potential energy landscape of a model glass former: thermodynamics,\n  anharmonicities, and finite size effects: It is possible to formulate the thermodynamics of a glass forming system in\nterms of the properties of inherent structures, which correspond to the minima\nof the potential energy and build up the potential energy landscape in the\nhigh-dimensional configuration space. In this work we quantitatively apply this\ngeneral approach to a simulated model glass-forming system. We systematically\nvary the system size between N=20 and N=160. This analysis enables us to\ndetermine for which temperature range the properties of the glass former are\ngoverned by the regions of the configuration space, close to the inherent\nstructures. Furthermore, we obtain detailed information about the nature of\nanharmonic contributions. Moreover, we can explain the presence of finite size\neffects in terms of specific properties of the energy landscape. Finally,\ndetermination of the total number of inherent structures for very small systems\nenables us to estimate the Kauzmann temperature.",
        "positive": "Self-Assembly and Waterlike Anomalies in Janus Nanoparticles: We explore the pressure versus temperature phase diagram of dimeric Janus\nnanoparticles using Molecular Dynamics simulations. The nanoparticle was\nmodeled as a dumbbells particle, and have one monomer that interacts by a\nstandard Lennard Jones potential and another monomer that is modeled using a\ntwo-length scale shoulder potential. Monomeric and dimeric systems modeled by\nthis shoulder potential show waterlike anomalies, and we investigate if a Janus\nnanoparticle composed by one anomalous monomer will exhibit anomalous behavior\nand self-assembly structures. The influence of the non-anomalous monomer in the\ndimeric system properties was explored. We show that the diffusion anomaly is\nmaintained, while the density anomaly can disappear depending on the\nnon-anomalous monomer characteristics. As well, the self-assembled structures\nare affected. Our results are discussed in the basis of the distinct\nmonomer-monomer interactions and on the two-length scale fluid characteristics."
    },
    {
        "anchor": "Monitoring spatially heterogeneous dynamics in a drying colloidal thin\n  film: We report on a new type of experiment that enables us to monitor spatially\nand temporally heterogeneous dynamic properties in complex fluids. Our approach\nis based on the analysis of near-field speckles produced by light diffusely\nreflected from the superficial volume of a strongly scattering medium. By\nperiodic modulation of an incident speckle beam we obtain pixel-wise ensemble\naverages of the structure function coefficient, a measure of the dynamic\nactivity. To illustrate the application of our approach we follow the different\nstages in the drying process of a colloidal thin film. We show that we can\naccess ensemble averaged dynamic properties on length scales as small as ten\nmicrometers over the full field of view.",
        "positive": "Viscous-poroelastic interaction as mechanism to create adhesion in\n  frogs' toe pads: The toe pads of frogs consist of soft hexagonal structures and a viscous\nliquid contained between and within the hexagonal structures. It has been\nhypothesized that this configuration creates adhesion by allowing for long\nrange capillary forces, or alternatively, by allowing for exit of the liquid\nand thus improving contact of the toe pad. In this work we suggest interaction\nbetween viscosity and elasticity as a mechanism to create temporary adhesion,\neven in the absence of capillary effects or van der Waals forces. We initially\nillustrate this concept experimentally by a simplified configuration consisting\nof two surfaces connected by a liquid bridge and elastic springs. We then\nutilize poroelastic mixture theory and model frog's toe pads as an elastic\nporous medium, immersed within a viscous liquid and pressed against a rigid\nrough surface. The flow between the surface and the toe pad is modeled by the\nlubrication approximation. Inertia is neglected and analysis of the\nelastic-viscous dynamics yields a governing partial differential equation\ndescribing the flow and stress within the porous medium. Several solutions of\nthe governing equation are presented and show a temporary adhesion due to\nstress created at the contact surface between the solids. This work thus may\nexplain how some frogs (such as the torrent frog) maintain adhesion underwater\nand the reason for the periodic repositioning of frogs' toe pads during\nadhesion to surfaces."
    },
    {
        "anchor": "Effect of Particle Size on the Suction Mechanism in Granular Grippers: Granular grippers are highly adaptable end-effectors that exploit the\nreversible jamming transition of granular materials to hold and manipulate\nobjects. Their holding force comes from the combination of three mechanisms:\nfrictional forces, geometrical constraints, and suction effects. In this work,\nwe experimentally study the effect of particle size on the suction mechanism.\nThrough X-ray computed tomography, we show that small particles (average\ndiameter d = 120 micrometers) achieve higher conformation around the object\nthan larger particles (d = 4mm), thus allowing the formation of air-tight\nseals. When the gripper is pulled off, mimicking lifting of an object, vacuum\npressure is generated in the sealed cavity at the interface gripper--object. If\nthe particles used as filling material are too large, the gripper does not\nconform closely around the object, leaving gaps between the gripper's membrane\nand the object. These gaps prevent the formation of sealed vacuum cavities\nbetween the object and the gripper and in turn hinder the suction mechanism\nfrom operating.",
        "positive": "Forced vibrations and wave propagation in multilayered solid spheres\n  using a one-dimensional semi-analytical finite element method: A numerical model is proposed to compute the eigenmodes and the forced\nresponse of multilayered elastic spheres. The main idea is to describe\nanalytically the problem along the angular coordinates with spherical harmonics\nand to discretize the radial direction with one-dimensional finite elements.\nThe proper test function must be carefully chosen so that both vector and\ntensor spherical harmonics orthogonality relationships can be used. The\nproposed approach yields a general one-dimensional formulation with a fully\nanalytical description of the angular behaviour, suitable for any interpolating\ntechnique. A linear eigenvalue problem, simple and fast to solve, is then\nobtained. The eigensolutions are the spheroidal and torsional modes. They are\nfavourably compared with literature results for a homogeneous sphere. The\neigensolutions are superposed to compute explicitly the forced response. The\nlatter is used to reconstruct the propagation of surfaces waves. In particular,\nthe collimation of a Rayleigh wave (non-diffracted surface wave propagating\nwith a quasi-constant width) excited by a line source in a homogeneous sphere\nis recovered with the model. Based on the vibration eigenmodes, a modal\nanalysis shows that such a wave is a superposition of fundamental spheroidal\nmodes with a displacement confined at the equator of the sphere. These modes\nare the so-called Rayleigh modes, of sectoral type and high polar wavenumbers.\nWhen a thin viscoelastic coating is added to the sphere, the Rayleigh mode\nbehaviour is recovered in a limited frequency range, allowing the generation of\na collimating wave at the interface between the sphere and the coating."
    },
    {
        "anchor": "Unification of classical nucleation theories via unified\n  It\u00f4-Stratonovich stochastic equation: Classical nucleation theory (CNT) is the most widely used framework to\ndescribe the early stage of first-order phase transitions. Unfortunately the\ndifferent points of view adopted to derive it yield different kinetic equations\nfor the probability density function, e.g. Zeldovich-Frenkel or\nBecker-D\\\"oring-Tunitskii equations. Starting from a phenomenological\nstochastic differential equation a unified equation is obtained in this work.\nIn other words, CNT expressions are recovered by selecting one or another\nstochastic calculus. Moreover, it is shown that the unified CNT thus obtained\nproduces the same Fokker-Planck equation as that from a recent update of CNT\n[J.F. Lutsko and M.A. Dur\\'an-Olivencia, J. Chem. Phys., 2013, 138, 244908]\nwhen mass transport is governed by diffusion. Finally, we derive a general\ninduction-time expression along with specific approximations of it to be used\nunder different scenarios. In particular, when the mass-transport mechanism is\ngoverned by direct impingement, volume diffusion, surface diffusion or\ninterface transfer.",
        "positive": "Wetting of ferrofluids: phenomena and control: Ferrofluids are liquids exhibiting remarkably strong response to magnetic\nfields, which leads to fascinating properties useful in various applications.\nUnderstanding the wetting properties and spreading of ferrofluids is important\nfor their use in microfluidics and magnetic actuation. However, this is\nchallenging as magnetically induced deformation of the ferrofluid surface can\naffect contact angles, which are commonly used to characterize wetting\nproperties in other systems. In addition, interaction of the magnetic\nnanoparticles and solid surface at nanoscale can have surprising effects on\nferrofluid spreading. In this review we discuss these issues with focus on\ninterpretation of ferrofluid contact angles. We review recent literature\nexamining ferrofluid wetting phenomena and outline novel wetting related\nferrofluid applications. To better understand wetting of ferrofluids, more\ncareful experimental work is needed."
    },
    {
        "anchor": "Droplet transport in a nanochannel coated by hydrophobic semiflexible\n  polymer brushes: the effect of chain stiffness: We study the influence of chain stiffness on droplet flow in a nano-channel,\ncoated with semiflexible hydrophobic polymers by means of non-equilibrium\nmolecular-dynamics simulations. The studied system is then a moving droplet in\nthe slit channel, coexisting with its vapor and subjected to periodic boundary\nconditions in the flow direction. The polymer chains, grafted by the terminal\nbead to the confining walls, are described by a coarse-grained model that\naccounts for chain connectivity, excluded volume interactions and local chain\nstiffness. The rheological, frictional and dynamical properties of the brush\nare explored over a wide range of persistence lengths. We find a rich behavior\nof polymer conformations and concomitant changes in the friction properties\nover the wide range of studied polymer stiffnesses. A rapid decrease in the\ndroplet velocity was observed as the rigidity of the chains is increased for\npolymers whose persistence length is smaller than their contour length. We find\na strong relation between the internal dynamics of the brush and the droplet\ntransport properties, which could be used to tailor flow properties by surface\nfunctionalization. The monomers of the brush layer, under the droplet, present\na collective \"treadmill belt\" like dynamics which can only be present due the\nthe existence of grafted chains. We describe its changes in spatial extension\nupon variations of polymer stiffness, with bidimensional velocity and density\nprofiles. The deformation of the polymer brushes due to the presence of the\ndroplet is analyzed in detail. Lastly, the droplet-gas interaction is studied\nby varying the liquid to gas ratio, observing a 16% speed increase for droplets\nthat flow close to each other, compared to a train of droplets that present a\nlarge gap between consecutive droplets.",
        "positive": "Weakly nonlinear analysis of two dimensional sheared granular flow: Weakly nonlinear analysis of a two dimensional sheared granular flow is\ncarried out under the Lees-Edwards boundary condition. We derive the time\ndependent Ginzburg-Landau (TDGL) equation of a disturbance amplitude starting\nfrom a set of granular hydrodynamic equations and discuss the bifurcation of\nthe steady amplitude in the hydrodynamic limit."
    },
    {
        "anchor": "Active restructuring of cytoskeleton composites leads to increased\n  mechanical stiffness, memory, and heterogeneity: The composite cytoskeleton, comprising interacting networks of semiflexible\nactin and rigid microtubules, actively generates forces and restructures using\nmotor proteins such as myosins to enable key mechanical processes including\ncell motility and mitosis. Yet, how motor-driven activity alters the mechanics\nof cytoskeleton composites remains an open challenge. Here, we perform optical\ntweezers microrheology on actin-microtubule composites driven by myosin II\nmotors to show that motor activity increases the linear viscoelasticity and\nelastic storage of the composite by active restructuring to a network of\ntightly-packed filament clusters and bundles. Our nonlinear microrheology\nmeasurements performed hours after cessation of activity show that the\nmotor-contracted structure is stable and robust to nonlinear forcing. Unique\nfeatures of the nonlinear response include increased mechanical stiffness,\nmemory and heterogeneity, coupled with suppressed filament bending following\nmotor-driven restructuring. Our results shed important new light onto the\ninterplay between viscoelasticity and non-equilibrium dynamics in active\npolymer composites such as the cytoskeleton.",
        "positive": "Amplitude dependent frequency, desynchronization, and stabilization in\n  noisy metapopulation dynamics: The enigmatic stability of population oscillations within ecological systems\nis analyzed. The underlying mechanism is presented in the framework of two\ninteracting species free to migrate between two spatial patches. It is shown\nthat that the combined effects of migration and noise cannot account for the\nstabilization. The missing ingredient is the dependence of the oscillations'\nfrequency upon their amplitude; with that, noise-induced differences between\npatches are amplified due to the frequency gradient. Migration among\ndesynchronized regions then stabilizes a \"soft\" limit cycle in the vicinity of\nthe homogenous manifold. A simple model of diffusively coupled oscillators\nallows the derivation of quantitative results, like the functional dependence\nof the desynchronization upon diffusion strength and frequency differences. The\noscillations' amplitude is shown to be (almost) noise independent. The results\nare compared with a numerical integration of the marginally stable\nLotka-Volterra equations. An unstable system is extinction-prone for small\nnoise, but stabilizes at larger noise intensity."
    },
    {
        "anchor": "Droplets on liquids and their long way into equilibrium: The morphological paths towards equilibrium droplets during the late stages\nof the dewetting process of a liquid film from a liquid substrate is\ninvestigated experimentally and theoretically. As liquids, short chained\npolystyrene (PS) and polymethyl-methacrylate (PMMA) are used, which can be\nconsidered as Newontian liquids well above their glass transition temperatures.\nCareful imaging of the PS/air interface of the droplets during equilibration by\n\\emph{in situ} scanning force microscopy and the PS/PMMA interface after\nremoval of the PS droplets reveal a surprisingly deep penetration of the PS\ndroplets into the PMMA layer. Droplets of sufficiently small volumes develop\nthe typical lens shape and were used to extract the ratio of the PS/air and\nPS/PMMA surface tensions and the contact angles by comparison to theoretical\nexact equilibrium solutions of the liquid/liquid system. Using these results in\nour dynamical thin-film model we find that before the droplets reach their\nequilibrium they undergo several intermediate stages each with a well-defined\nsignature in shape. Moreover, the intermediate droplet shapes are independent\nof the details of the initial configuration, while the time scale they are\nreached depend strongly on the droplet volume. This is shown by the numerical\nsolutions of the thin-film model and demonstrated by quantitative comparison to\nexperimental results.",
        "positive": "Self-mixing in microtubule-kinesin active fluid from nonuniform to\n  uniform distribution of activity: Active fluids have applications in micromixing, but little is known about the\nmixing kinematics of systems with spatiotemporally-varying activity. To\ninvestigate, UV-activated caged ATP was used to activate controlled regions of\nmicrotubule-kinesin active fluid and the mixing process was observed with\nfluorescent tracers and molecular dyes. At low P\\'eclet numbers (diffusive\ntransport), the active-inactive interface progressed toward the inactive area\nin a diffusion-like manner that was described by a simple model combining\ndiffusion with Michaelis-Menten kinetics. At high P\\'eclet numbers (convective\ntransport), the active-inactive interface progressed in a superdiffusion-like\nmanner that was qualitatively captured by an active-fluid hydrodynamic model\ncoupled to ATP transport. Results showed that active fluid mixing involves\ncomplex coupling between distribution of active stress and active transport of\nATP and reduces mixing time for suspended components with decreased impact of\ninitial component distribution. This work will inform application of active\nfluids to promote micromixing in microfluidic devices."
    },
    {
        "anchor": "Rheological properties of a dilute suspension of self-propelled\n  particles: With a detail microscopic model for a self-propelled swimmer, we derive the\nrheological properties of a dilute suspension of such particles at small Peclet\nnumbers. It is shown that, in addition to the Einstein's like contribution to\nthe effective viscosity, that is proportional to the volume fraction of the\nswimmers, a contribution due to the activity of self-propelled particles\ninfluences the viscosity. As a result of the activity of swimmers, the\neffective viscosity would be a lower (higher) than the viscosity of the\nsuspending medium when the particles are pushers (pullers). Such activity\ndependent contribution, will also results to a non-Newtonian behavior of the\nsuspension in the form of normal stress differences.",
        "positive": "Ring closure in actin polymers: We present an analysis for the ring closure probability of semiflexible\npolymers within the pure bend Worm Like Chain (WLC) model. The ring closure\nprobability predicted from our analysis can be tested against fluorescent actin\ncyclization experiments.We also discuss the effect of ring closure on bend\nangle fluctuations in actin polymers."
    },
    {
        "anchor": "Dynamics of cylindrical domain walls in nematic liquid crystals: Analytical calculations of the dynamics of a curved domain wall in a nematic\nliquid crystal are performed. The core of the wall is assumed to form a\ncylinder, whose axis coincides with the direction of an external magnetic\nfield. The equation of motion for the nematic director field is solved in a\ncomoving coordinate frame by applying a polynomial expansion of the tilt angle\nwith respect to the radial distance from the wall core. Starting from a\ncylindrical domain wall at rest as initial conditions, the shrinking of the\ncylinder and the change of the wall width is analysed in detail. In particular,\nwe find that the Neel wall decays faster than the Bloch wall, in agreement with\nenergy considerations.",
        "positive": "Self-Sustained Density Oscillations of Swimming Bacteria Confined in\n  Microchambers: We numerically study the dynamics of run-and-tumble particles confined in two\nchambers connected by thin channels. Two dominant dynamical behaviors emerge:\n(i) an oscillatory pumping state, in which particles periodically fill the two\nvessels and (ii) a circulating flow state, dynamically maintaining a near\nconstant population level in the containers when connected by two channels. We\ndemonstrate that the oscillatory behaviour arises from the combination of a\nnarrow channel, preventing bacteria reorientation, and a density dependent\nmotility inside the chambers."
    },
    {
        "anchor": "On the pressure exerted by a bundle of independent living filaments: The properties of a bundle of grafted semi-flexible living filaments in ideal\nsolution facing an obstacle wall, under supercritical conditions, are explored.\nFor this purpose, we make use of the discrete wormlike chain model\ncharacterized by the monomer size $d$, a size dependent contour length $L_{\\rm\nc}$ and a persistence length $l_{\\rm p}$. The calculation of the equilibrium\nfilament size distribution and the average equilibrium force require the\nknowledge of the wall effect on the single filament partition function of any\nsize, which can be computed by Metropolis Monte-Carlo methods. The force\nexerted by a living filament on a fixed wall turns out to be the weighted\naverage of the dead grafted filament forces computed for sizes hitting the\nwall, multiplied by the probability of occurrence of the corresponding filament\nsize. As the distance to the wall is varied, the resultant force shows large\nvariations whose amplitude decrease with increasing gap sizes and/or with\ndecreasing persistence length. Also, its average over a gap interval of precise\nsize $d$ gives an average force close to what is expected by the ratchet model\nfor actin growth against a wall. The osmotic pressure exerted by $N_f$\nfilaments is the average equilibrium force per filament times the grafting\nsurface density.",
        "positive": "Mechanically induced helix-coil transition in biopolymer networks: The quasi-equilibrium evolution of the helical fraction occurring in a\nbiopolymer network (gelatin gel) under an applied stress has been investigated\nby observing modulation in its optical activity. Its variation with the imposed\nchain extension is distinctly non-monotonic and corresponds to the transition\nof initially coiled strands to induced left-handed helices. The experimental\nresults are in qualitative agreement with theoretical predictions of helices\ninduced on chain extension. This new effect of mechanically stimulated\nhelix-coil transition has been studied further as a function of the elastic\nproperties of the polymer network: crosslink density and network aging."
    },
    {
        "anchor": "3D Spectroscopic Tracking of Individual Brownian Nanoparticles during\n  Galvanic Exchange: Monitoring chemical reactions in solutions at the scale of individual\nentities is challenging: single particle detection requires small confocal\nvolumes which are hardly compatible with Brownian motion, particularly when\nlong integration times are necessary. Here, we propose a real-time (10 Hz)\nholography-based nm-precision 3D tracking of single moving nanoparticles. Using\nthis localization, the confocal collection volume is dynamically adjusted to\nfollow the moving nanoparticle and allow continuous spectroscopic monitoring.\nThis concept is applied to the study galvanic exchange in freely-moving\ncollo{\\\"i}dal silver nanoparticles with gold ions generated in-situ. While the\nBrownian trajectory reveals particle size, spectral shifts dynamically reveal\ncomposition changes and transformation kinetics at the single object level,\npointing at different transformation kinetics for free and tethered particles.",
        "positive": "Role of inertia in two-dimensional deformation and breakup of a droplet: We investigate by Lattice Boltzmann methods the effect of inertia on the\ndeformation and break-up of a two-dimensional fluid droplet surrounded by fluid\nof equal viscosity (in a confined geometry) whose shear rate is increased very\nslowly. We give evidence that in two dimensions inertia is {\\em necessary} for\nbreak-up, so that at zero Reynolds number the droplet deforms indefinitely\nwithout breaking. We identify two different routes to breakup via two-lobed and\nthree-lobed structures respectively, and give evidence for a sharp transition\nbetween these routes as parameters are varied."
    },
    {
        "anchor": "Intermittent relaxation and avalanches in extremely persistent active\n  matter: We use numerical simulations to study the dynamics of dense assemblies of\nself-propelled particles in the limit of extremely large, but finite,\npersistence times. In this limit, the system evolves intermittently between\nmechanical equilibria where active forces balance interparticle interactions.\nWe develop an efficient numerical strategy allowing us to resolve the\nstatistical properties of elastic and plastic relaxation events caused by\nactivity-driven fluctuations. The system relaxes via a succession of scale-free\nelastic events and broadly distributed plastic events that both depend on the\nsystem size. Correlations between plastic events lead to emergent dynamic\nfacilitation and heterogeneous relaxation dynamics. Our results show that\ndynamical behaviour in extremely persistent active systems is qualitatively\nsimilar to that of sheared amorphous solids, yet with some important\ndifferences.",
        "positive": "Anisotropic line tension of lipid domains in monolayers: We formulate a simple effective model to describe molecular interactions in a\nlipid monolayer. The model represents lipid molecules in terms of\ntwo-dimensional anisotropic particles on the plane of the monolayer. These\nparticles interact through forces that are believed to be relevant for the\nunderstanding of fundamental properties of the monolayer: van der Waals\ninteractions originating from lipid chain interaction, and dipolar forces\nbetween the dipole groups of the molecular heads. Thermodynamic and phase\nbehaviour properties of the model are explored using density-functional theory.\nInterfacial properties, such as the line tension and the structure of the\nregion between ordered and disordered coexisting regions, are also calculated.\nThe line tension turns out to be highly anisotropic, mainly as a result of the\nlipid chain tilt, and to a lesser extent of dipolar interactions perpendicular\nto the monolayer. The role of the two dipolar components, parallel and\nperpendicular to the monolayer, is assessed by comparing with computer\nsimulation results for lipid monolayers."
    },
    {
        "anchor": "What controls thermo-osmosis? Molecular simulations show the critical\n  role of interfacial hydrodynamics: Thermo-osmotic and related thermo-phoretic phenomena can be found in many\nsituations from biology to colloid science, but the underlying molecular\nmechanisms remain largely unexplored. Using molecular dynamics simulations, we\nmeasured the thermo-osmosis coefficient by both mechano-caloric and\nthermo-osmotic routes, for different solid-liquid interfacial energies. The\nsimulations reveal in particular the crucial role of nanoscale interfacial\nhydrodynamics. For non-wetting surfaces , thermo-osmotic transport is largely\namplified by hydrodynamic slip at the interface. For wetting surfaces, the\nposition of the hydrodynamic shear plane plays a key role in determining the\namplitude and sign of the thermo-osmosis coefficient. Finally, we measure a\ngiant thermo-osmotic response of the water-graphene interface, which we relate\nto the very low interfacial friction displayed by this system. These results\nopen new perspectives for the design of efficient functional interfaces for,\ne.g., waste heat harvesting.",
        "positive": "Geometric theory of topological defects: methodological developments and\n  new trends: Liquid crystals generally support orientational singularities of the director\nfield known as topological defects. These latter modifiy transport properties\nin their vicinity as if the geometry was non-Euclidean. We present a state of\nthe art of the differential geometry of nematic liquid crystals, with a special\nemphasis on linear defects. We then discuss unexpected but deep connections\nwith cosmology and high-energy-physics, and conclude with a review on defect\nengineering for transport phenomena."
    },
    {
        "anchor": "A Ternary Lattice Boltzmann Model for Amphiphilic Fluids: A lattice Boltzmann model for amphiphilic fluid dynamics is presented. It is\na ternary model, in that it conserves mass separately for each chemical species\npresent (water, oil, amphiphile), and it maintains an orientational degree of\nfreedom for the amphiphilic species. Moreover, it models fluid interactions at\nthe microscopic level by introducing self-consistent forces between the\nparticles, rather than by positing a Landau free energy functional. This\ncombination of characteristics fills an important need in the hierarchy of\nmodels currently available for amphiphilic fluid dynamics, enabling efficient\ncomputer simulation and furnishing new theoretical insight. Several\ncomputational results obtained from this model are presented and compared to\nexisting lattice-gas model results. In particular, it is noted that lamellar\nstructures, which are precluded by the Peierls instability in two-dimensional\nsystems with kinetic fluctuations, are not observed in lattice-gas models, but\nare easily found in the corresponding lattice Boltzmann models. This points out\na striking difference in the phenomenology accessible to each type of model.",
        "positive": "Relation of vibrational excitations and thermal conductivity to elastic\n  heterogeneities in disordered solids: In crystals, molecules thermally vibrate around the periodic lattice sites.\nVibrational motions are well understood in terms of phonons, which carry heat\nand control heat transport. The situation is notably different in disordered\nsolids, where vibrational excitations are not phonons and can be even\nlocalized. Recent numerical work has established the concept of elastic\nheterogeneity: disordered solids show inhomogeneous local mechanical response.\nClearly, the heterogeneous nature of elastic properties strongly influences\nvibrational and thermal properties, and it is expected to be the origin of\nanomalous features, including boson peak, vibrational localization, and\ntemperature dependence of thermal conductivity. These are all crucial\nlong-standing problems in materials physics, which we address in the present\nwork. We have considered a toy model able to stabilize different states of\nmatter, by introducing an increasing amount of size disorder. The phase diagram\ngenerated by molecular dynamics simulations encompasses the perfect crystalline\nstate with a spatially homogeneous elastic moduli distribution, multiple\ndefective phases with increasing moduli heterogeneities, and eventually a\nseries of amorphous states. We have established clear correlations among the\nheterogeneous local mechanical response, vibrational states, and thermal\nconductivity. We provide evidence that elastic heterogeneity controls both\nvibrational and thermal properties, and is a key concept to understand the\nanomalous puzzling features of disordered solids."
    },
    {
        "anchor": "Rate-dependent adhesion of viscoelastic contacts. Part I: contact area\n  and contact line velocity within model multi-asperity contacts with rubber: In this work, we investigate dissipative effects involved during the\ndetachment of a smooth spherical glass probe from a viscoelastic silicone\nsubstrate patterned with micro-asperities. As a baseline, the pull-off of a\nsingle asperity, millimeter-sized contact between a glass lens and a smooth\npoly(dimethylsiloxane) (PDMS) rubber is first investigated as a function of the\nimposed detachment velocity. From a measurement of the contact radius a(t) and\nnormal load during unloading, the dependence of the strain energy relase rate G\non the velocity of the contact line vc = da/dt is determined under the\nassumption that viscoelastic dissipation is localized at the edge of the\ncontact. These data are incorporated into Muller's model (V.M. Muller J Adh Sci\nTech (1999) 13 999-1016) in order to predict the time-dependence of the contact\nsize. Similar pull-off experiments are carried out with the same PDMS substrate\npatterned with spherical micro-asperities with a prescribed height\ndistribution. From in situ optical measurements of the micro-contacts, scaling\nlaws are identified for the contact radius a and the contact line velocity vc.\nOn the basis of the observed similarity between macro and microscale contacts,\na numerical solution is developed to predict the reduction of the contact\nradius during unloading.",
        "positive": "Effects of Particle Shape on Growth Dynamics at Edges of Evaporating\n  Colloidal Drops: We study the influence of particle shape on growth processes at the edges of\nevaporating drops. Aqueous suspensions of colloidal particles evaporate on\nglass slides, and convective flows during evaporation carry particles from drop\ncenter to drop edge, where they accumulate. The resulting particle deposits\ngrow inhomogeneously from the edge in two-dimensions, and the deposition front,\nor growth line, varies spatio-temporally. Measurements of the fluctuations of\nthe deposition front during evaporation enable us to identify distinct growth\nprocesses that depend strongly on particle shape. Sphere deposition exhibits a\nclassic Poisson like growth process; deposition of slightly anisotropic\nparticles, however, belongs to the Kardar-Parisi-Zhang (KPZ) universality\nclass, and deposition of highly anisotropic ellipsoids appears to belong to a\nthird universality class, characterized by KPZ fluctuations in the presence of\nquenched disorder."
    },
    {
        "anchor": "Swirling and snaking, 3D oscillatory bifurcations of vesicle dynamics in\n  microcirculation: Vesicles are soft elastic bodies with distinctive mechanical properties such\nas bending resistance, membrane fluidity, and their strong ability to deform,\nmimicking some properties of biological cells. While previous three-dimensional\n(3D) studies have identified stationary shapes such as slipper and axisymmetric\nones, we report a complete phase diagram of 3D vesicle dynamics in a bounded\nPoiseuille flow with two more oscillatory dynamics, 3D snaking and swirling. 3D\nsnaking is characterized by planar oscillatory motion of the mass center and\nshape deformations, which is unstable and leads to swirling or slipper.\nSwirling emerges from supercritical pitchfork bifurcation. The mass center\nmoves along a helix, the preserved shape rolls on itself and spins around the\nflow direction. Swirling can coexist with slipper.",
        "positive": "Collapse of Flexible Polyelectrolytes in Multivalent Salt Solutions: The collapse of flexible polyelectrolytes in a solution of multivalent\ncounterions is studied by means of a two state model. The states correspond to\nrod-like and spherically collapsed conformations respectively. We focus on the\nvery dilute monomer concentration regime where the collapse transition is found\nto occur when the charge of the multivalent salt is comparable (but smaller) to\nthat of the monomers. The main contribution to the free energy of the collapsed\nconformation is linear in the number of monomers $N$, since the internal state\nof the collapsed polymer approaches that of an amorphous ionic solid. The free\nenergy of the rod-like state grows as $N\\ln N$, due to the electrostatic energy\nassociated with that shape. We show that practically all multivalent\ncounterions added to the system are condensed into the polymer chain, even\nbefore the collapse."
    },
    {
        "anchor": "Structures and pathways for clathrin self-assembly in the bulk and on\n  membranes: We present a coarse-grained model of clathrin that is simple enough to be\ncomputationally tractable yet includes key observed qualitative features: a\ntriskelion structure with excluded volume between legs; assembly of polymorphic\ncages in the bulk; formation of buds on a membrane. We investigate the assembly\nof our model using both Monte Carlo simulations and molecular dynamics with\nhydrodynamic interactions, in the latter employing a new membrane boundary\ncondition. In the bulk, a range of known clathrin structures are assembled. A\nmembrane budding pathway involving the coalescence of multiple small clusters\nis identified.",
        "positive": "Self-assembly of monodisperse clusters: Dependence on target geometry: We apply a simple model system of patchy particles to study monodisperse\nself-assembly, using the Platonic solids as target structures. We find marked\ndifferences between the assembly behaviours of the different systems.\nTetrahedra, octahedra and icosahedra assemble easily, while cubes are more\nchallenging and dodecahedra do not assemble. We relate these differences to the\nkinetics and thermodynamics of assembly, with the formation of large disordered\naggregates a particular important competitor to correct assembly. In\nparticular, the free energy landscapes of those targets that are easy to\nassemble are funnel-like, whereas for the dodecahedral system the landscape is\nrelatively flat with little driving force to facilitate escape from disordered\naggregates."
    },
    {
        "anchor": "In-silico modeling of the micromechanics of fibrous scaffolds and\n  stiffness sensing by cells: Mechanical properties of the tissue engineering scaffolds are known to play a\ncrucial role in tissue regeneration. Here, we have utilized discrete network\nand finite element models to study fibrous scaffold mechanics and its\ndependence on structure. We have considered two loading conditions, first,\nuniaxial elongation (macroscopic), and second, localized cellular forces\n(microscopic). Using these two scenarios, we have tried to establish a link\nbetween scaffold micromechanics and its macroscopic mechanical properties. We\nhave demonstrated that the macroscopic elastic modulus of fibrous scaffold is\ndependent on the sample shape, size and the degree of fiber fusion. Under\nmicroscopic loading conditions the deformation of the fibrous scaffolds is\nanisotropic with an orientation dependent decay with distance. Further, we\nexplored the stiffness sensing under the conditions of fixed stress or fixed\nstrain application by the cells. With fixed strain, we found that the stiffness\nsensed by a cell is proportional to scaffold's macroscopic Young's modulus.\nHowever, for fixed stress application, it also depends on cell's elasticity\nwith stiffness experienced by stiff and soft cells differing by an order of\nmagnitude. The analyses demonstrate that there exists a gap between mechanical\nproperties of the fibrous scaffolds as measured from the macroscopic testings\nand those sensed by the cells. This warrants a need for extreme care during the\ndesigning and reporting of experiments involving cell-scaffold interactions.\nThe insights from this work will help in the designing of tissue engineering\nscaffolds for applications where mechanical stimuli are a critical factor",
        "positive": "Translational and orientational glass transitions in the\n  large-dimensional limit : a generalized replicated liquid theory and an\n  application to patchy colloids: We developed a generalized replicated liquid theory for glassy phases of\nnon-spherical uniaxial molecules and colloids, which becomes exact in the large\ndimensional limit $d\\to\\infty$. We then applied the scheme to patchy colloids\nwith sticky patches at their heads and tails. The system exhibits rich phase\nbehaviors involving the translational and orientational degrees of freedom. We\nfound a novel glass-glass transition between glasses with large/small\norientational fluctuations."
    },
    {
        "anchor": "Numerical insights on ionic microgels: structure and swelling behaviour: Recent progress has been made in the numerical modelling of neutral microgel\nparticles with a realistic, disordered structure. In this work we extend this\napproach to the case of co-polymerised microgels where a thermoresponsive\npolymer is mixed with acidic groups. We compare the cases where counterions\ndirectly interact with microgel charges or are modelled implicitly through a\nDebye-H\\\"uckel description. We do so by performing extensive numerical\nsimulations of single microgels across the volume phase transition (VPT)\nvarying the temperature and the fraction of charged monomers. We find that the\npresence of charges considerably alters the microgel structure, quantified by\nthe monomer density profiles and by the form factors of the microgels,\nparticularly close to the VPT. We observe significant deviations between the\nimplicit and explicit models, with the latter comparing more favourably to\navailable experiments. In particular, we observe a shift of the VPT temperature\nto larger values as the amount of charged monomers increases. We also find that\nbelow the VPT the microgel-counterion complex is almost neutral, while it\ndevelops a net charge above the VPT. Interestingly, under these conditions the\ncollapsed microgel still retains a large amount of counterions inside its\nstructure. Since these interesting features cannot be captured by the implicit\nmodel, our results show that it is crucial to explicitly include the\ncounterions in order to realistically model ionic thermoresponsive microgels.",
        "positive": "Local Changes in Protein Filament Properties Drive Large-Scale Membrane\n  Transformations Involved in Endosome Tethering and Fusion: Large-scale cellular transformations are triggered by subtle physical and\nstructural changes in individual biomacromolecular and membrane components. A\nprototypical example of such an event is the orchestrated fusion of membranes\nwithin an endosome that enables transport of cargo and processing of\nbiochemical moieties. In this work, we demonstrate how protein filaments on the\nendosomal membrane surface can leverage a rigid-to-flexible transformation to\nelicit a large-scale change in membrane flexibility to enable membrane fusion.\nWe develop a polymer field-theoretic model that captures molecular alignment\narising from nematic interactions with varying surface density and fraction of\nflexible filaments, which are biologically controlled within the endosomal\nmembrane. We then predict the collective elasticity of the filament brush in\nresponse to changes in the filament alignment, predicting a greater than\n20-fold increase of the effective membrane elasticity over the bare membrane\nelasticity that is triggered by filament alignment. These results show that the\nendosome can modulate the filament properties to orchestrate membrane\nfluidization that facilitates vesicle fusion, providing an example of how\nactive processes that modulate local molecular properties can result in\nlarge-scale transformations that are essential to cellular survival."
    },
    {
        "anchor": "Non-Gaussian statistics for the motion of self-propelled Janus\n  particles: experiment versus theory: Spherical Janus particles are one of the most prominent examples for active\nBrownian objects. Here, we study the diffusiophoretic motion of such\nmicroswimmers in experiment and in theory. Three stages are found: simple\nBrownian motion at short times, super-diffusion at intermediate times, and\nfinally diffusive behavior again at long times. These three regimes observed in\nthe experiments are compared with a theoretical model for the Langevin dynamics\nof self-propelled particles with coupled translational and rotational motion.\nBesides the mean square displacement also higher displacement moments are\naddressed. In particular, theoretical predictions regarding the non-Gaussian\nbehavior of self-propelled particles are verified in the experiments.\nFurthermore, the full displacement probability distribution is analyzed, where\nin agreement with Brownian dynamics simulations either an extremely broadened\npeak or a pronounced double-peak structure is found depending on the\nexperimental conditions.",
        "positive": "Lifetime of oil drops pressed by buoyancy against a planar interface:\n  Large drops: In a previous report [10] it was shown that emulsion stability simulations\nare able to reproduce the lifetime of micrometer-size drops of hexadecane\npressed by buoyancy against a planar water-hexadecane interface. It was\nconfirmed that small drops (ri<10 {\\mu}m) stabilized with {\\beta}-casein behave\nas nondeformable particles, moving with a combination of Stokes and Taylor\ntensors as they approach the interface. Here, a similar methodology is used to\nparametrize the potential of interaction of drops of soybean oil stabilized\nwith bovine serum albumin. The potential obtained is then employed to study the\nlifetime of deformable drops in the range 10 \\leq ri \\leq 1000 {\\mu}m. It is\nestablished that the average lifetime of these drops can be adequately\nreplicated using the model of truncated spheres. However, the results depend\nsensibly on the expressions of the initial distance of deformation and the\nmaximum film radius used in the calculations. The set of equations adequate for\nlarge drops is not satisfactory for medium-size drops (10 \\leq ri \\leq 100\n{\\mu}m), and vice versa. In the case of large particles, the increase in the\ninterfacial area as a consequence of the deformation of the drops generates a\nvery large repulsive barrier which opposes coalescence. Nevertheless, the\nbuoyancy force prevails. As a consequence, it is the hydrodynamic tensor of the\ndrops which determine the characteristic behavior of the lifetime as a function\nof the particle size. While the average values of the coalescence time of the\ndrops can be justified by the mechanism of film thinning, the scattering of the\nexperimental data of large drops cannot be rationalized using the methodology\npreviously described. A possible explanation of this phenomenon required\nelaborate simulations which combine deformable drops, capillary waves,\nrepulsive interaction forces, and a time-dependent surfactant adsorption."
    },
    {
        "anchor": "Nonreciprocal collective dynamics in a mixture of phoretic Janus\n  colloids: A multicomponent mixture of Janus colloids with distinct catalytic coats and\nphoretic mobilities is a promising theoretical system to explore the collective\nbehavior arising from nonreciprocal interactions. An active colloid produces\n(or consumes) chemicals, self-propels, drifts along chemical gradients, and\nrotates its intrinsic polarity to align with a gradient. As a result the\nconnection from microscopics to continuum theories through coarse-graining\ncouples densities and polarization fields in unique ways. Focusing on a binary\nmixture, we show that these couplings render the unpatterned reference state\nunstable to small perturbations through a variety of instabilities including\noscillatory ones which arise on crossing an exceptional point or through a Hopf\nbifurcation. For fast relaxation of the polar fields, they can be eliminated in\nfavor of the density fields to obtain a microscopic realization of the\nNonreciprocal Cahn-Hilliard model for two conserved species with two distinct\nsources of non-reciprocity, one in the interaction coefficient and the other in\nthe interfacial tension. Our work establishes Janus colloids as a versatile\nmodel for a bottom-up approach to both scalar and polar active mixtures.",
        "positive": "Low-frequency vibrations of jammed packings in large spatial dimensions: Amorphous packings prepared in the vicinity of the jamming transition play a\ncentral role in theoretical studies of the vibrational spectrum of glasses. Two\nmean-field theories predict that the vibrational density of states $g(\\omega)$\nobeys a characteristic power law, $g(\\omega)\\sim\\omega^2$, called the non-Debye\nscaling in the low-frequency region. Numerical studies have however reported\nthat this scaling breaks down at low frequencies, due to finite dimensional\neffects. In this study, we prepare amorphous packings of up to $128000$\nparticles in spatial dimensions from $d=3$ to $d=9$ to characterise the range\nof validity of the non-Debye scaling. Our numerical results suggest that the\nnon-Debye scaling is obeyed down to a frequency that gradually decreases as $d$\nincreases, and possibly vanishes for large $d$, in agreement with mean-field\npredictions. We also show that the prestress is an efficient control parameter\nto quantitatively compare packings across different spatial dimensions."
    },
    {
        "anchor": "Connections of activated hopping processes with the breakdown of the\n  Stokes-Einstein relation and with aspects of dynamical heterogeneities: We develop a new extended version of the mode-coupling theory (MCT) for glass\ntransition, which incorporates activated hopping processes via the dynamical\ntheory originally formulated to describe diffusion-jump processes in crystals.\nThe dynamical-theory approach adapted here to glass-forming liquids treats\nhopping as arising from vibrational fluctuations in quasi-arrested state where\nparticles are trapped inside their cages, and the hopping rate is formulated in\nterms of the Debye-Waller factors characterizing the structure of the\nquasi-arrested state. The resulting expression for the hopping rate takes an\nactivated form, and the barrier height for the hopping is ``self-generated'' in\nthe sense that it is present only in those states where the dynamics exhibits a\nwell defined plateau. It is discussed how such a hopping rate can be\nincorporated into MCT so that the sharp nonergodic transition predicted by the\nidealized version of the theory is replaced by a rapid but smooth crossover. We\nthen show that the developed theory accounts for the breakdown of the\nStokes-Einstein relation observed in a variety of fragile glass formers. It is\nalso demonstrated that characteristic features of dynamical heterogeneities\nrevealed by recent computer simulations are reproduced by the theory. More\nspecifically, a substantial increase of the non-Gaussian parameter, double-peak\nstructure in the probability distribution of particle displacements, and the\npresence of a growing dynamic length scale are predicted by the extended MCT\ndeveloped here, which the idealized version of the theory failed to reproduce.\nThese results of the theory are demonstrated for a model of the Lennard-Jones\nsystem, and are compared with related computer-simulation results and\nexperimental data.",
        "positive": "Theory of liquid crystal anchoring at a porous surface: Using classical density functional theory (DFT) the effect of bringing a\nliquid crystal (LC) into contact with a porous substrate or matrix is\ninvestigated. The DFT used is a combination of the Onsager approximation to\nevaluate the excess free energy of the LC fluid and quenched annealed DFT to\nevaluate the interaction between the fluid and the porous substrate. When the\nfluid alignment far from the substrate is held perpendicular to its surface\nthere is a thin layer of fluid aligned parallel to the substrate surface for\nlow matrix densities. For higher matrix densities this director deformation\npropagates into the bulk of the fluid. Consideration of a system without\nconfining walls suggests that for low matrix densities normal alignment is\nmetastable compared to parallel alignment, while for higher matrix densities it\nis unstable."
    },
    {
        "anchor": "A platform for nanomagnetism - assembled ferromagnetic and\n  antiferromagnetic dipolar tubes: We report an interesting case where magnetic phenomena can transcend\nmesoscopic scales. Our system consists of tubes created by assembly of dipolar\nspheres. The cylindrical topology results in the breakup of degeneracy observed\nin the planar square and triangular packings. As far as the ground state is\nconcerned, tubes switch from circular to axial magnetization with increasing\ntube length. All magnetostatic properties found in magnetic nanotubes, in which\nthe dipolar interaction is comparable or dominate over the exchange\ninteraction, are reproduced by the dipolar tubes including an intermediary\nhelically magnetized state. Besides, we discuss antiferromagnetic phases and an\ninteresting intermediary vortex state resulting from the square arrangement of\nthe dipolar spheres.",
        "positive": "Effects of Alignment Activity on the Collapse Kinetics of a Flexible\n  Polymer: Dynamics of various biological filaments can be understood within the\nframework of active polymer models. Here we consider a bead-spring model for a\nflexible polymer chain in which the active interaction among the beads is\nintroduced via an alignment rule adapted from the Vicsek model. Following a\nquench from the high-temperature coil phase to a low-temperature state point,\nwe study the coarsening kinetics via molecular dynamics (MD) simulations using\nthe Langevin thermostat. For the passive polymer case the low-temperature\nequilibrium state is a compact globule. Results from our MD simulations reveal\nthat though the globular state is also the typical final state in the active\ncase, the nonequilibrium pathways to arrive at such a state differ from the\npassive picture due to the alignment interaction among the beads. We notice\nthat deviations from the intermediate \"pearl-necklace\"-like arrangement, that\nis observed in the passive case, and the formation of more elongated\ndumbbell-like structures increase with increasing activity. Furthermore, it\nappears that while a small active force on the beads certainly makes the\ncoarsening process much faster, there exists nonmonotonic dependence of the\ncollapse time on the strength of active interaction. We quantify these\nobservations by comparing the scaling laws for the collapse time and growth of\npearls with the passive case."
    },
    {
        "anchor": "On the Apparent Yield Stress in Non-Brownian Magnetorheological Fluids: We use simulations to probe the flow properties of dense two-dimensional\nmagnetorheological fluids. Prior results from both experiments and simulations\nreport that the shear stress $\\sigma$ scales with strain rate $\\dot \\gamma$ as\n$\\sigma \\sim \\dot \\gamma^{1-\\Delta}$, with values of the exponent ranging\nbetween $2/3 <\\Delta \\le 1$. However it remains unclear what properties of the\nsystem select the value of $\\Delta$, and in particular under what conditions\nthe system displays a yield stress ($\\Delta = 1$). To address these questions,\nwe perform simulations of a minimalistic model system in which particles\ninteract via long ranged magnetic dipole forces, finite ranged elastic\nrepulsion, and viscous damping. We find a surprising dependence of the apparent\nexponent $\\Delta$ on the form of the viscous force law. For experimentally\nrelevant values of the volume fraction $\\phi$ and the dimensionless Mason\nnumber (which quantifies the competition between viscous and magnetic\nstresses), models using a Stokes-like drag force show $\\Delta \\approx 0.75$ and\nno apparent yield stress. When dissipation occurs at the contact, however, a\nclear yield stress plateau is evident in the steady state flow curves. In\neither case, increasing $\\phi$ towards the jamming transition suffices to\ninduce a yield stress. We relate these qualitatively distinct flow curves to\nclustering mechanisms at the particle scale. For Stokes-like drag, the system\nbuilds up anisotropic, chain-like clusters as the Mason number tends to zero\n(vanishing strain rate and/or high field strength). For contact damping, by\ncontrast, there is a second clustering mechanism due to inelastic collisions.",
        "positive": "Microrheology of viscoelastic solutions studied by magnetic rotational\n  spectroscopy: Magnetic rotational spectroscopy is based on the use of magnetic micron-size\nwires for viscosity measurements. Submitted to a rotational magnetic field with\nincreasing frequency, the wires undergo a hydrodynamic instability between a\nsynchronous and an asynchronous regime. From a comparison between predictions\nand experiments, the static shear viscosity and elastic modulus of wormlike\nmicellar solutions are here determined. The values agree with the determination\nby cone-and-plate rheometry."
    },
    {
        "anchor": "Constructing thermodynamically consistent models with a non-ideal\n  equation of state: A recently introduced particle-based model for fluid dynamics with continuous\nvelocities is generalized to model fluids with excluded volume effects. This is\nachieved through the use of biased stochastic multi-particle collisions which\ndepend on local velocities and densities and conserve momentum and kinetic\nenergy. The equation of state is derived and criteria for the correct choice of\ncollision probabilities are discussed. In particular, it is shown how a naive\nimplementation can lead to inconsistent density fluctuations.",
        "positive": "Dynamics of Snapping Beams and Jumping Poppers: We consider the dynamic snapping instability of elastic beams and shells.\nUsing the Kirchhoff rod and F\\\"{o}ppl-von K\\'{a}rm\\'{a}n plate equations, we\nstudy the stability, deformation modes, and snap-through dynamics of an elastic\narch with clamped boundaries and subject to a concentrated load. For parameters\ntypical of everyday and technological applications of snapping, we show that\nthe stretchability of the arch plays a critical role in determining not only\nthe post-buckling mode of deformation but also the timescale of snapping and\nthe frequency of the arch's vibrations about its final equilibrium state. We\nshow that the growth rate of the snap-through instability and its subsequent\nringing frequency can both be interpreted physically as the result of a sound\nwave in the material propagating over a distance comparable to the length of\nthe arch. Finally, we extend our analysis of the ringing frequency of indented\narches to understand the `pop' heard when everted shell structures snap-through\nto their stable state. Remarkably, we find that not only are the scaling laws\nfor the ringing frequencies in these two scenarios identical but also the\nrespective prefactors are numerically close; this allows us to develop a master\ncurve for the frequency of ringing in snapping beams and shells."
    },
    {
        "anchor": "Collective Variables for the Study of Crystallization: The phenomenon of solidification of a substance from its liquid phase is of\nthe greatest practical and theoretical importance, and atomistic simulations\ncan provide precious information towards its understanding and control.\nUnfortunately, the time scale for crystallization is much larger than what can\nbe explored in standard simulations. Enhanced sampling methods can overcome\nthis time scale hurdle. Here we employ the on-the-fly probability enhanced\nsampling method that is a recent evolution of metadynamics. This method, like\nmany others, relies on the definition of appropriate collective variables able\nto capture the slow degrees of freedom. To this effect we introduce collective\ncoordinates of general applicability to crystallization simulations. They are\nbased on the peaks of the three-dimensional structure factor that are combined\nnon-linearly via the Deep Linear Discriminant Analysis machine learning method.\nWe apply the method to the study of crystallization of a multicomponent system,\nSodium Chloride and a molecular system, Carbon Dioxide.",
        "positive": "Proper formulation of viscous dissipation for nonlinear waves in solids: In order to model nonlinear viscous dissipative motions in solids, acoustical\nphysicists usually add terms linear in dot{E}, the material time derivative of\nthe Lagrangian strain tensor E, to the elastic stress tensor sigma derived from\nthe expansion to the third- (sometimes fourth-) order of the strain energy\ndensity e=e(trace(E), trace(E^2), trace(E^3)). Here, it is shown that this\npractice, which has been widely used in the past three decades or so, is\nphysically wrong for at least two reasons, and that it should be corrected. One\nreason is that the elastic stress tensor sigma is not symmetric while dot{E) is\nsymmetric, so that motions for which sigma + sigma^T <> 0 will give rise to\nelastic stresses which have no viscous pendant. Another reason is that dot{E}\nis frame-invariant, while sigma is not, so that an observer transformation\nwould alter the elastic part of the total stress differently than it would\nalter the dissipative part, thereby violating the fundamental principle of\nmaterial frame-indifference. These problems can have serious consequences for\nnonlinear shear wave propagation in soft solids, as seen here with an example\nof a kink in almost incompressible soft solids."
    },
    {
        "anchor": "Interaction between random heterogeneously charged surfaces in an\n  electrolyte solution: We study, using Monte Carlo simulations, the interaction between infinite\nheterogeneously charged surfaces inside an electrolyte solution. The surfaces\nare overall neutral with quenched charged domains. An average over the quenched\ndisorder is performed to obtain the net force. We find that the interaction\nbetween the surfaces is repulsive at short distances and is attractive for\nlarger separations.",
        "positive": "Supercoil formation in DNA denaturation: We generalize the Poland-Scheraga (PS) model to the case of a circular DNA,\ntaking into account the twisting of the two strains around each other. Guided\nby recent single-molecule experiments on DNA strands, we assume that the\ntorsional stress induced by denaturation enforces formation of supercoils whose\nwrithe absorbs the linking number expelled by the loops. Our model predicts\nthat, when the entropy parameter of a loop satisfies $c \\le 2$, denaturation\ntransition does not take place. On the other hand for $c>2$ a first-order\ndenaturation transition is consistent with our model and may take place in the\nactual system, as in the case with no supercoils. These results are in contrast\nwith other treatments of circular DNA melting where denaturation is assumed to\nbe accompanied by an increase in twist rather than writhe on the bound\nsegments."
    },
    {
        "anchor": "Self-assembly near Ground State: Randomly Pack Granular Spheres and\n  Cubes into Crystal: Self-assembly of granular particles is of great interest in both applied and\nbasic research. It is commonly observed that when randomly packed into a\ncontainer, granular particles form disordered structures like glass. As the\nparticles are athermal, the self-assembly of such packings can normally be\ndirected with energy input via vibration or shear. However, here we show that\nin particular containers, mono-sized spheres and cubes can self-assemble into\nperfect crystals when randomly dropped in. This is because the favourable\nmicrostates for new particles are jammed in the ordered structure by the\nexisting particles and the boundary synergistically. Such a self-assembly\nmethod has not been reported in the literature. It indicates that disordered\npacking structure may result from the conflict between the internal structure\nand the structure shaped by the boundary. Therefore, to bridge such\ninconsistency could be a general principle for directing self-assembly for\ndifferent kinds of particles in emerging areas.",
        "positive": "Simulations of viscous shape relaxation in shuffled foam clusters: We simulate the shape relaxation of foam clusters and compare them with the\ntime exponential expected for Newtonian fluid. Using two-dimensional Potts\nModel simulations, we artificially create holes in a foam cluster and shuffle\nit by applying shear strain cycles. We reproduce the experimentally observed\ntime exponential relaxation of cavity shapes in the foam as a function of the\nnumber of strain steps. The cavity rounding up results from local rearrangement\nof bubbles, due to the conjunction of both a large applied strain and local\nbubble wall fluctuations."
    },
    {
        "anchor": "Tracer diffusivity in a time or space dependent temperature field: The conventional assumption that the self-diffusion coefficient of a small\ntracer can be obtained by a local and instantaneous application of Einstein's\nrelation in a temperature field with spatial and temporal heterogeneity is\nrevisited. It is shown that hydrodynamic fluctuations contribute to the\nself-diffusion tensor in a universal way, i.e. independent of the size and\nshape of the tracer. The hydrodynamic contribution is anisotropic--it reflects\nknowledge of the global anisotropy in the temperature profile, leading to\nanisotropic self-diffusion tensor for a spherical tracer. It is also\nretarded--it creates memory effects during the diffusion process due to\nhydrodynamic interactions.",
        "positive": "Quasi long-ranged order in two-dimensional active liquid crystals: Quasi-long ranged order is the hallmark of two-dimensional liquid crystals.\nAt equilibrium, this property implies that the correlation function of the\nlocal orientational order parameter decays with distance as a power law: i.e.\n$\\sim|\\boldsymbol{r}|^{-\\eta_{p}}$, with $\\eta_{p}$ a temperature-dependent\nexponent. While in general non-universal, $\\eta_{p}=1/4$ universally at the\nBerezinskii-Kosterlitz-Thouless transition, where orientational order is lost\nbecause of the unbinding of disclinations. Motivated by recent experimental\nfindings of liquid crystal order in confluent cell monolayers, here we\ndemonstrate that, in {\\em active} liquid crystals, the notion of quasi-long\nranged order fundamentally differs from its equilibrium counterpart and is\nultimately dictated by the interplay between translational and orientational\ndynamics. As a consequence, the exponent $\\eta_{p}$ is allowed to vary in the\nrange $0<\\eta_{p}\\le 2$, with the upper bound corresponding to the isotropic\nphase. Our theoretical predictions are supported by a survey of recent\nexperimental data, reflecting a wide variety of different realization of\norientational order in two dimensions."
    },
    {
        "anchor": "Numerical and Experimental Investigation of Static Wetting Morphologies\n  of Aqueous Drops on Lubricated Slippery Surfaces Using a Quasi-Static\n  Approach: Due to the slow dynamics of the wetting ridge, it is challenging to predict\nthe wetting morphology of liquid drops on thin lubricant coated surfaces. It is\nhypothesized that when a drop sinks on a lubricated surface, quasi-static\nwetting morphology can be numerically computed only from the knowledge of\ninterfacial energies, lubricant thickness, and drop volume. We used Surface\nEvolver software for the numerical computation of the interface profiles for a\nfour-phase system. For the experiments, we used drops of 80 wt% formamide on\nsilicone oil coated substrates with varying lubricant thickness, substrate\nwettability and drop volume. Optical images of drops were used to compare the\nexperimental interfacial profiles and apparent contact angles with the\nnumerically computed ones. We found good agreement between the experiments and\nthe simulations for the interfacial profiles and apparent contact angles as a\nfunction of various systems parameters except for very thin lubricating films.\nApparent contact angles varied non-linearly as a function of substrate\nwettability and lubricant thickness, however, were found constant with the drop\nvolume.",
        "positive": "Aging mechanism in tunable Pickering emulsion: We study the stability of a model Pickering emulsion system. A special\ncounter-flow microfluidics set-up was used to prepare monodisperse Pickering\nemulsions, with oil droplets in water. The wettability of the monodisperse\nsilica nanoparticles (NPs) could be tuned by surface grafting and the surface\ncoverage of the droplets was controlled using the microfluidics setup. A\nsurface coverage as low as 23$\\%$ is enough to stabilize the emulsions and we\nevidence a new regime of Pickering emulsion stability where the surface\ncoverage of emulsion droplets of constant size increases in time, in\ncoexistence with a large amount of dispersed phase. Our results demonstrate\nthat the previously observed limited coalescence regime where surface coverage\ntends to control the average size of the final droplets must be put in a\nbroader perspective."
    },
    {
        "anchor": "Periodic motion of sedimenting flexible knots: We study the dynamics of knotted deformable closed chains sedimenting in a\nviscous fluid. We show experimentally that trefoil and other torus knots often\nattain a remarkably regular horizontal toroidal structure while sedimenting,\nwith a number of intertwined loops, oscillating periodically around each other.\nWe then recover this motion numerically and find out that it is accompanied by\na very slow rotation around the vertical symmetry axis. We analyze the\ndependence of the characteristic time scales on the chain flexibility and\naspect ratio. It is observed in the experiments that this oscillating mode of\nthe dynamics can spontaneously form even when starting from a qualitatively\ndifferent initial configuration. In numerical simulations, the oscillating\nmodes are usually present as transients or final stages of the evolution,\ndepending on chain aspect ratio and flexibility, and the number of loops.",
        "positive": "Making soft solids flow: microscopic bursts and conga lines in jammed\n  emulsions: It is well known that jammed soft materials will flow if sheared above their\nyield stress - think mayonnaise spread on bread - but a complete microscopic\ndescription of this seemingly sim- ple process has yet to emerge. What remains\nelusive is a microscopic framework that explains the macroscopic flow, derived\nfrom a 3-D spatially resolved analysis of the dynamics of the droplets or\nparticles that compose the soft material. By combining confocal-rheology\nexperiments on compressed emulsions and numerical simulations, we unravel that\nthe primary microscopic mechanisms for flow are strongly influenced by the rate\nof the imposed deformation. When shearing fast, small coordinated clusters of\ndroplets move collectively as in a conga line, while at low rates the flow\nemerges from bursts of droplet rearrangements, correlated over large domains.\nThese regions exhibit complex spatio-temporal correlation patterns that reflect\nthe long range elasticity embedded in the jammed material. These results\nidentify the three-dimensional structure of microscopic rearrangements within\nsheared soft solids, revealing that the characteristic shape and dynamics of\nthese structures are strongly determined by the rate of the external shear."
    },
    {
        "anchor": "Polymorphism in tubulin assemblies: a mechanical model: We investigate the mechanical origin of polymorphic structures in\ntwo-dimensional tubulin assemblies, of which microtubules are the best known\nexample. These structures feature twisted ribbons, flat tubulin sheets,\nmacrotubules, and hoops, and they spontaneously assemble depending on the\nchemical environment. Upon modelling tubulin aggregates as minimally\nanisotropic elastic shells and using a combination of numerical simulations and\nanalytical work, we show that the mechanical strain in tubulin lattices,\noriginating from asymmetries at the single dimer level, naturally gives rise to\npolymorphic assemblies, among which cylinders and other tubular structures are\npredominant for a wide range of values of spontaneous curvature. Furthermore,\nour model suggests that switching the sign of the sheets' spontaneous Gaussian\ncurvature from positive (i.e. sphere-like) to negative (i.e. saddle-like),\ncould provide a possible route to microtubules disassembly.",
        "positive": "Cluster-induced deagglomeration in dilute gravity-driven gas-solid flows\n  of cohesive grains: Clustering is often presumed to lead to enhanced agglomeration between\ncohesive grains due to the reduced relative velocities of particles within a\ncluster. Our discrete-particle simulations on gravity-driven, gas-solid flows\nof cohesive grains exhibit the opposite trend, revealing a new mechanism we\ncoin \"cluster-induced deagglomeration.\" Specifically, we examine relatively\ndilute gas-solid flows and isolate agglomerates of cohesive origin from overall\nheterogeneities in the system, i.e., agglomerates of cohesive origin and\nclusters of hydrodynamic origin. We observe enhanced clustering with an\nincreasing system size (as is the norm for noncohesive systems) as well as\nreduced agglomeration. The reduced agglomeration is traced to the increased\ncollisional impact velocities of particles at the surface of a cluster; i.e.,\nhigher levels of clustering lead to larger relative velocities between the\nclustered and nonclustered regions, thereby serving as an additional source of\ngranular temperature. This physical picture is further evidenced by a\ntheoretical model based on a balance between the generation and breakage rates\nof agglomerates. Finally, cluster-induced deagglomeration also provides an\nexplanation for a surprising saturation of agglomeration levels in\ngravity-driven, gas-solid systems with increasing levels of cohesion, as\nopposed to the monotonically increasing behavior seen in free-evolving or\ndriven granular systems in the absence of gravity. Namely, higher cohesion\nleads to more energy dissipation, which is associated with competing effects:\nenhanced agglomeration and enhanced clustering, the latter of which results in\nmore cluster-induced deagglomeration."
    },
    {
        "anchor": "Effects of strain stiffening and electrostriction on tunable elastic\n  waves in compressible dielectric elastomer laminates: This paper presents an electromechanical analysis of the nonlinear static\nresponse and the superimposed small-amplitude wave characteristics in an\ninfinite periodic compressible dielectric elastomer (DE) laminate subjected to\nelectrostatic excitations and prestress in the thickness direction. The\nenriched Gent material model is employed to account for the effects of strain\nstiffening and electrostriction of the DE laminate. The theory of nonlinear\nelectroelasticity and related linearized incremental theory are exploited to\nderive the governing equations of nonlinear response and the dispersion\nrelations of incremental shear and longitudinal waves. Numerical results reveal\nthat the snap-through instability of a Gent DE laminate resulting from\ngeometrical and material nonlinearities can be used to achieve a sharp\ntransition in the position and width of wave band gaps. Furthermore, the\ninfluence of material properties (including Gent constants, the second strain\ninvariant and electrostrictive parameters) and that of prestress on the\nsnap-through instability and the electrostatic tunability of band gaps for both\nshear and longitudinal waves are discussed in detail. The electrostrictive\neffect and prestress are beneficial to stabilizing the periodic DE laminate.\nDepending on whether the snap-through instability occurs or not, a continuous\nvariation or a sharp transition in wave band gaps can be realized by varying\nthe electric stimuli. Our numerical findings are expected to provide a solid\nguidance for the design and manufacture of soft DE wave devices with tunable\nband structures.",
        "positive": "The partition of energy for air-fluidized grains: The dynamics of one and two identical spheres rolling in a nearly-levitating\nupflow of air obey the Langevin Equation and the Fluctuation-Dissipation\nRelation [Ojha et al. Nature 427, 521 (2004) and Phys. Rev. E 71, 01631\n(2005)]. To probe the range of validity of this statistical mechanical\ndescription, we perturb the original experiments in four ways. First, we break\nthe circular symmetry of the confining potential by using a stadium-shaped\ntrap, and find that the velocity distributions remain circularly symmetric.\nSecond, we fluidize multiple spheres of different density, and find that all\nhave the same effective temperature. Third, we fluidize two spheres of\ndifferent size, and find that the thermal analogy progressively fails according\nto the size ratio. Fourth, we fluidize individual grains of aspherical shape,\nand find that the applicability of statistical mechanics depends on whether or\nnot the grain chatters along its length, in the direction of airflow."
    },
    {
        "anchor": "Screened Coulomb interactions of general macroions with nonzero particle\n  volume: A semianalytical approach is developed to calculate the effective pair\npotential of rigid arbitrarily shaped macroions with a nonvanishing particle\nvolume, valid within linear screening theory and the mean-field approximation.\nThe essential ingredient for this framework is a mapping of the particle to a\nsingular charge distribution with adjustable effective charge and shape\nparameters determined by the particle surface electrostatic potential. For\ncharged spheres this method reproduces the well-known\nDerjaguin-Landau-Verwey-Overbeek (DLVO) potential. Further exemplary benchmarks\nof the method for more complicated cases, like tori, triaxial ellipsoids, and\nadditive torus-sphere mixtures, leads to accurate closed-form integral\nexpressions for all particle separations and orientations. The findings are\nrelevant for determining the phase behaviour of macroions with experiments and\nsimulations for various particle shapes.",
        "positive": "Computational Simulations of Solvation Force and Squeeze Out of Dodecane\n  Chain Molecules in Atomic Force Microscopy: There is a growing interest since the 1990s to understand the squeezing and\nshear behaviors of liquid films at nanometer scale by the atomic force\nmicroscope (AFM) measurement. We carry out all-atom contact-mode AFM\nsimulations in a liquid-vapor molecular dynamics ensemble to investigate the\nsolvation force oscillation and squeeze out mechanisms of a confined linear\ndodecane fluid between a gold AFM tip and a mica substrate. Solvation force\noscillations are found to be associated with the layering transition of liquid\nfilm and unstable jumps of AFM tip position. Detailed structural analyses and\nmolecular animations show that the local permeation of chain molecules and the\nsqueeze out of molecules near the edge of contact promote the layering\ntransition under compression. The confinement-induced slow down dynamics is\nmanifested by the decrease in diffusivity and increase in rotational relaxation\ntimes. However, the persistent diffusive behavior of dodecane chain molecules\neven in the single-monolayer film is attributed to the chain sliding motions,\ngiven the fact that substantial vacancy space exists in the film due to thermal\nfluctuations."
    },
    {
        "anchor": "Disordered Solids Without Well-Defined Transverse Phonons: The Nature of\n  Hard Sphere Glasses: We probe the Ioffe-Regel limits of glasses with repulsions near the\nzero-temperature jamming transition by measuring the dynamical structure\nfactors. At zero temperature, the transverse Ioffe-Regel frequency vanishes at\nthe jamming transition with a diverging length, but the longitudinal one does\nnot, which excludes the existence of a diverging length associated with the\nlongitudinal excitations. At low temperatures, the transverse and longitudinal\nIoffe-Regel frequencies approach zero at the jamming-like transition and glass\ntransition, respectively. As a consequence, glasses between the glass\ntransition and jamming-like transition, which are hard sphere glasses in the\nlow temperature limit, can only carry well-defined longitudinal phonons and\nhave an opposite pressure dependence of the ratio of the shear modulus to the\nbulk modulus from glasses beyond the jamming-like transition.",
        "positive": "Vacancy diffusion in colloidal crystals as determined by dynamical\n  density-functional theory and the phase-field-crystal model: A two-dimensional crystal of repulsive dipolar particles is studied in the\nvicinity of its melting transition by using Brownian dynamics computer\nsimulation, dynamical density functional theory and phase-field crystal\nmodelling. A vacancy is created by taking out a particle from an equilibrated\ncrystal and the relaxation dynamics of the vacancy is followed by monitoring\nthe time-dependent one-particle density. We find that the vacancy is quickly\nfilled up by diffusive hopping of neighbouring particles towards the vacancy\ncenter. We examine the temperature dependence of the diffusion constant and\nfind that it decreases with decreasing temperature in the simulations. This\ntrend is reproduced by the dynamical density functional theory. Conversely, the\nphase field crystal calculations predict the opposite trend. Therefore, the\nphase-field model needs a temperature-dependent expression for the mobility to\npredict trends correctly."
    },
    {
        "anchor": "Evaporation effects in elastocapillary aggregation: We consider the effect of evaporation on the aggregation of a number of\nelastic objects due to a liquid's surface tension. In particular, we consider\nan array of spring--block elements in which the gaps between blocks are filled\nby thin liquid films that evaporate during the course of an experiment. Using\nlubrication theory to account for the fluid flow within the gaps, we study the\ndynamics of aggregation. We find that a non-zero evaporation rate causes the\nelements to aggregate more quickly and, indeed, to contact within finite time.\nHowever, we also show that the number of elements within each cluster decreases\nas the evaporation rate increases. We explain these results quantitatively by\ncomparison with the corresponding two-body problem and discuss their relevance\nfor controlling pattern formation in elastocapillary systems.",
        "positive": "Time-domain Brillouin Scattering as a Local Temperature Probe in Liquids: We present results of time-domain Brillouin scattering (TDBS) to determine\nthe local temperature of liquids in contact to an optical transducer. TDBS is\nbased on an ultrafast pump-probe technique to determine the light scattering\nfrequency shift caused by the propagation of coherent acoustic waves in a\nsample. Since the temperature influences the Brillouin scattering frequency\nshift, the TDBS signal probes the local temperature of the liquid. Results for\nthe extracted Brillouin scattering frequencies recorded at different liquid\ntemperatures and at different laser powers - i.e. different steady state\nbackground temperatures- are shown to demonstrate the usefulness of TDBS as a\ntemperature probe. This TDBS experimental scheme is a first step towards the\ninvestigation of ultrathin liquids measured by GHz ultrasonic probing."
    },
    {
        "anchor": "Poly-dispersity and deformation effects on pore throat size in granular\n  beds: Static granular packings play a central role in numerous industrial\napplications and natural settings. In these situations, fluid or fine particle\nflow through a bed of static particles is heavily influenced by the narrowest\npassage connecting the pores of the packing, commonly referred to as pore\nthroats or constrictions. Existing studies predominantly assume monodisperse\nrigid particles, but this is an oversimplification of the problem. In this\nwork, we illustrate the connection between pore throat size, polydispersity,\nand particle deformation. Simple analytical expressions are provided to link\nthese properties of the packing, followed by examples from Discrete Element\nMethod (DEM) simulations of fine particle percolation demonstrating the impact\nof polydispersity and particle deformation. Our intent is to emphasize the\nsubstantial impact of polydispersity and particle deformation on constriction\nsize, underscoring the importance of accounting for these effects in particle\ntransport in granular packings.",
        "positive": "Stability of Soft Quasicrystals in a Coupled-Mode Swift-Hohenberg Model\n  for Three-Component Systems: In this article, we discuss the stability of soft quasicrystalline phases in\na coupled-mode Swift-Hohenberg model for three-component systems, where the\ncharacteristic length scales are governed by the positive-definite gradient\nterms. Classic two-mode approximation method and direct numerical minimization\nare applied to the model. In the latter approach, we apply the projection\nmethod to deal with the potentially quasiperiodic ground states. A variable\ncell method of optimizing the shape and size of higher-dimensional periodic\ncell is developed to minimize the free energy with respect to the order\nparameters. Based on the developed numerical methods, we rediscover decagonal\nand dodecagonal quasicrystalline phases, and find diverse periodic phases and\ncomplex modulated phases. Furthermore, phase diagrams are obtained in various\nphase spaces by comparing the free energies of different candidate structures.\nIt does show not only the important roles of system parameters, but also the\neffect of optimizing computational domain. In particular, the optimization of\ncomputational cell allows us to capture the ground states and phase behavior\nwith higher fidelity. We also make some discussions on our results and show the\npotential of applying our numerical methods to a larger class of mean-field\nfree energy functionals."
    },
    {
        "anchor": "Multiple dynamic regimes in a coarsening foam: We use differential dynamic microscopy and particle tracking to determine the\ndynamical characteristics of a coarsening foam in reciprocal and direct space.\nAt all wavevectors $q$ investigated, the intermediate scattering function\nexhibits a compressed exponential decay. However, the access to unprecedentedly\nsmall $q$s highlights the existence of two distinct regimes for the\n$q$-dependence of the foam relaxation rate $\\Gamma (q)$. At any given foam age,\n$\\Gamma (q)\\sim q$ at high $q$, consistent with directionally-persistent and\nintermittent bubble displacements. At low $q$, we find $\\Gamma (q) \\sim\nq^{1.6}$. We show that such change in $q$-dependence of $\\Gamma (q)$ relates to\na bubble displacement distribution exhibiting a cut-off length of the order of\nthe bubble diameter. Investigations of the $q$-dependence of $\\Gamma (q)$ at\ndifferent foam ages reveal that foam dynamics is not only governed by the\nbubble length scale, but also by the strain rate imposed by the bubble growth;\nnormalizing $\\Gamma (q)$ by this strain rate and multiplying $q$ with the\nage-dependent bubble radius leads to a collapse of all data sets onto a unique\nmaster-curve.",
        "positive": "The van Hove distribution function for Brownian hard spheres: dynamical\n  test particle theory and computer simulations for bulk dynamics: We describe a test particle approach based on dynamical density functional\ntheory (DDFT) for studying the correlated time evolution of the particles that\nconstitute a fluid. Our theory provides a means of calculating the van Hove\ndistribution function by treating its self and distinct parts as the two\ncomponents of a binary fluid mixture, with the `self' component having only one\nparticle, the `distinct' component consisting of all the other particles, and\nusing DDFT to calculate the time evolution of the density profiles for the two\ncomponents. We apply this approach to a bulk fluid of Brownian hard spheres and\ncompare to results for the van Hove function and the intermediate scattering\nfunction from Brownian dynamics computer simulations. We find good agreement at\nlow and intermediate densities using the very simple Ramakrishnan-Yussouff\n[Phys. Rev. B 19, 2775 (1979)] approximation for the excess free energy\nfunctional. Since the DDFT is based on the equilibrium Helmholtz free energy\nfunctional, we can probe a free energy landscape that underlies the dynamics.\nWithin the mean-field approximation we find that as the particle density\nincreases, this landscape develops a minimum, while an exact treatment of a\nmodel confined situation shows that for an ergodic fluid this landscape should\nbe monotonic. We discuss possible implications for slow, glassy and arrested\ndynamics at high densities."
    },
    {
        "anchor": "Nanofluidic charge transport under strong electrostatic coupling\n  conditions: The comprehensive depiction of the many-body effects governing nanoconfined\nelectrolytes is an essential step for the conception of nanofluidic devices\nwith optimized performance. By incorporating self-consistently multivalent\ncharges into the Poisson-Boltzmann equation dressed by a background monovalent\nsalt, we investigate the impact of strong-coupling electrostatics on the\nnanofluidic transport of electrolyte mixtures. We find that the experimentally\nobserved negative streaming currents in anionic nanochannels originate from the\ncollective effect of the Cl attraction by the interfacially adsorbed\nmultivalent cations, and the no-slip layer reducing the hydrodynamic\ncontribution of these cations to the net current. The like-charge current\ncondition emerging from this collective mechanism is shown to be the reversal\nof the average potential within the no-slip zone. Applying the formalism to\nsurface-coated membrane nanoslits located in the giant dielectric permittivity\nregime, we reveal a new type of streaming current activated by attractive\npolarization forces. Under the effect of these forces, the addition of\nmultivalent ions into the KCl solution sets a charge separation and generates a\ncounterion current between the neutral slit walls. The adjustability of the\ncurrent characteristics solely via the valency and amount of the added\nmultivalent ions identifies the underlying process as a promising mechanism for\nnanofluidic ion separation purposes.",
        "positive": "Mixing and segregation of ring polymers: spatial confinement and\n  molecular crowding effects: During the life cycle of bacterial cells the non-mixing of the two\nring-shaped daughter genomes is an important prerequisite for the cell division\nprocess. Mimicking the environments inside highly crowded biological cells, we\nstudy the dynamics and statistical behaviour of two flexible ring polymers in\nthe presence of cylindrical confinement and crowding molecules. From extensive\ncomputer simulations we determine the degree of ring-ring overlap and the\nnumber of inter-monomer contacts for varying volume fractions $\\phi$ of\ncrowders. We also examine the entropic de-mixing of polymer rings in the\npresence of mobile crowders and determine the characteristic times of the\ninternal polymer dynamics. Effects of the ring length on ring-ring overlap are\nalso analysed. In particular, on systematic variation of the fraction of\ncrowding molecules a $(1-\\phi)$-scaling is found for the ring-ring overlap\nlength along the cylinder axis, and a non-monotonic dependence of the 3D\nring-ring contact number is predicted. Our results help to rationalise the\nimplications of macromolecular crowding for circular DNA molecules in confined\nspaces inside bacteria as well as in localised cellular compartments inside\neukaryotic cells."
    },
    {
        "anchor": "Why do Thin Polymer Films Melt at Lower Temperature? A Continuum\n  Approach: We have investigated the reduction of the glass transition temperature,\n$T_g$, for thin supported films of particularly small molecular weight ($M_W$ =\n2 kg/mol) polystyrene, and found good agreement with earlier studies on larger\nmolecules. By combining the eigenmodes of the films with mode coupling theory,\nwe arrive at a simple and predictive model which is in quantitative agreement\nwith the data. Its only fitting parameter is the shear modulus governing the\nrelevant fluctuations. The weak dependence of the latter upon the molecular\nweight of the polymer is in accordance with the general observation that the\nreduction of $T_g$ is largely independent of chain length at sufficiently low\nmolecular weight.",
        "positive": "Exotic liquid crystalline phases in monolayers of vertically vibrated\n  granular particles: Vibrated monolayers of granular particles confined into horizontal cavities\nform a variety of fluid patterns with orientational order that resemble\nequilibrium liquid-crystal phases. In some cases one can identify nematic and\nsmectic patters that can be understood in terms of classical statistical\nmechanics of hard bodies. Low aspect ratio cylinders project as rectangles and\nform uniaxial, or 2-atic, and tetratic, or 4-atic, nematic phases. Other\npolygonal particles may exhibit different liquid-crystal phases, in general\n$p$-atic phases, of higher symmetries. We give a brief summary of theoretical\nwork on rectangles and triangles, and provide some experimental results on\nvibrated monolayers. In the case of equilateral triangles, the theory predicts\nan exotic triatic phase, or 6-atic phase, with six-fold symmetry and three\nequivalent directors. Right-angled triangles exhibit a 4-atic phase with strong\noctatic (8-atic) correlations. Experiments on cylinders show 4-atic textures\nand, even more remarkable, geometric frustration caused by confinement excites\ntopological defects, which seem to follow the same topological rules as\nstandard liquid crystals. Some of our findings can be understood with the help\nof simulations of hard particles subject to thermal equilibrium, although\nstandard Density-Functional Theories fail to account for the correct\nequilibrium phases in some cases."
    },
    {
        "anchor": "Polymer Detachment Kinetics from Adsorbing Surface: Theory, Simulation\n  and Similarity to Infiltration into Porous Medium: The force-assisted desorption kinetics of a macromolecule from adhesive\nsurface is studied theoretically, using the notion of tensile (Pincus) blobs,\nas well as by means of Monte-Carlo (MC) and Molecular Dynamics (MD)\nsimulations. We show that the change of detached monomers with time is governed\nby a differential equation which is equivalent to the nonlinear porous medium\nequation (PME), employed widely in transport modeling of hydrogeological\nsystems. Depending on the pulling force and the strength of adsorption, three\nkinetic regimes can be distinguished: (i) \"trumpet\" (weak adsorption and small\npulling force), (ii) \"stem-trumpet\" (weak adsorption and moderate force), and\n(iii) \"stem\" (strong adsorption and large force). Interestingly, in all regimes\nthe number of desorbed beads $M(t)$, and the height of the first monomer (which\nexperiences a pulling force) $R(t)$ above the surface follow an universal\nsquare-root-of-time law. Consequently, the total time of detachment $<\\tau_d>$,\nscales with polymer length $N$ as $<\\tau_d> \\propto N^2$. Our main theoretical\nconclusions are tested and found in agreement with data from extensive MC- and\nMD-simulations.",
        "positive": "Curvature Induced Activation of a Passive Tracer in an Active Bath: We use numerical simulations to study the motion of a large asymmetric tracer\nimmersed in a low density suspension of self-propelled nanoparticles in two\ndimensions. Specifically, we analyze how the curvature of the tracer affects\nits translational and rotational motion in an active environment. We find that\neven very small amounts of curvature are sufficient for the active bath to\nimpart directed motion to the tracer which results in its effective activation.\nWe propose simple scaling arguments to characterize this induced activity in\nterms of the curvature of the tracer and the strength of the self-propelling\nforce. Our results suggest new ways of controlling the transport properties of\npassive tracers in an active medium by carefully tailoring their geometry."
    },
    {
        "anchor": "Are better conducting molecules more rigid?: We investigate the electronic origin of the bending stiffness of conducting\nmolecules. It is found that the bending stiffness associated with electronic\nmotion, which we refer to as electro-stiffness, $\\kappa_{e}$, is governed by\nthe molecular orbital overlap $t$ and the gap width $u$ between HOMO and LUMO\nlevels, and behaves as $\\kappa_{e}\\sim t^{2}/\\sqrt{u^2+t^{2}}$. To study the\neffect of doping, we analyze the electron filling-fraction dependence on\n$\\kappa_{e}$ and show that doped molecules are more flexible. In addition, to\nestimate the contribution of $\\kappa_{e}$ to the total stiffness, we consider\nmolecules under a voltage bias, and study the length contraction ratio as a\nfunction of the voltage. The molecules are shown to be contracted or dilated,\nwith $\\kappa_{e}$ increasing nonlinearly with the applied bias.",
        "positive": "Compression stiffening in biological tissues: on the possibility of\n  classic elasticity origins: Compression stiffening, or an increase in shear modulus with increasing\ncompressive strain, has been observed in recent rheometry experiments on brain,\nliver, and fat tissues. Here, we extend the known types of biomaterials\nexhibiting this phenomenon to include agarose gel and fruit flesh. Further, we\nshow that two different results from classic elasticity theory can account for\nthe phenomenon of linear compression stiffening. One result is due to Barron\nand Klein, extended here to the relevant geometry and pre-stresses; the other\nis due to Birch. For incompressible materials, there are no adjustable\nparameters in either theory. Which one applies to a given situation is a matter\nof reference state, suggesting that the reference state is determined by the\ntendency of the material to develop, or not develop, axial stress (in excess of\nthe applied pre-stress) when subjected to torsion at constant axial strain. Our\nexperiments and analysis also strengthen the notion that seemingly distinct\nanimal and plant tissues can have mechanically similar behavior under certain\nconditions."
    },
    {
        "anchor": "Elastic Property of Membranes Self-assembled from Diblock and Triblock\n  Copolymers: The elastic property of membranes self-assembled from AB diblock and ABA\ntriblock copolymers, as coarse-grained model of lipids and the bolalipids, are\nstudied using the self-consistent field theory (SCFT). Specifically, solutions\nof the SCFT equations, corresponding to membranes in different geometries\n(planar, cylindrical, spherical, and pore) have been obtained for a model\nsystem composed of amphiphilic AB diblock copolymers and ABA triblock\ncopolymers dissolved in A homopolymers. The free energy of the membranes with\ndifferent geometries is then used to extract the bending modulus, Gaussian\nmodulus, and line tension of the membranes. The results reveal that the bending\nmodulus of the triblock membrane is greater than that of the diblock membrane.\nFurthermore, the Gaussian modulus and line tension of the triblock membrane\nindicate that the triblock membranes have higher pore formation energy than\nthat of the diblock membranes. The equilibrium bridging and looping fractions\nof the triblock copolymers are also obtained. Implications of the theoretical\nresults on the elastic properties of biologically equivalent lipid bilayers and\nthe bolalipid membranes are discussed.",
        "positive": "Shape induced segregation and anomalous particle transport under\n  spherical confinement: Colloid or nanoparticle mobility under confinement is of central importance\nto a wide range of physical and biological processes. Here, we introduce a\nminimal model of particles in a hydrodynamic continuum to examine how particle\nshape and concentration affect the transport of particles in spherical\nconfinement. Specifically, an immersed boundary-General geometry Ewald-like\napproach is adopted to simulate the dynamics of spheres and cylinders under the\ninfluence of short-and long-range fluctuating hydrodynamic interactions with\nappropriate non-slip conditions at the confining walls. An efficient\n$\\it{O(N)}$ parallel finite element algorithm is used, thereby allowing\nsimulations at high concentrations, while a Chebyshev polynomial approximation\nis implemented in order to satisfy the fluctuation-dissipation theorem. A\nconcentration-dependent anomalous diffusion is observed for suspended\nparticles. It is found that introducing cylinders in a background of spheres,\ni.e. particles with a simple degree of anisotropy, has a pronounced influence\non the structure and dynamics of the particles. First, increasing the fraction\nof cylinders induces a particle segregation effect, where spheres are pushed\ntowards the wall and cylinders remain near the center of the cavity. This\nsegregation leads to lower mobility for the spheres relative to that\nencountered in a system of pure spheres at the same volume fraction. Second,\nthe diffusive-to-anomalous transition and the degree of anomaly--quantified by\nthe power-law exponent in the mean square displacement vs. time relation-both\nincrease as the fraction of cylinders becomes larger. These findings are of\nrelevance for studies of diffusion in the cytoplasm, where proteins exhibit a\ndistribution of size and shapes that could lead to some of the effects\nidentified in the simulations reported here."
    },
    {
        "anchor": "Effective boundary conditions for dense granular flows: We derive an effective boundary condition for granular flow taking into\naccount the effect of the heterogeneity of the force network on sliding\nfriction dynamics. This yields an intermediate boundary condition which lies in\nthe limit between no-slip and Coulomb friction; two simple functions relating\nwall stress, velocity, and velocity variance are found from numerical\nsimulations. Moreover, we show that this effective boundary condition\ncorresponds to Navier slip condition when GDR MiDi's model is assumed to be\nvalid, and that the slip length depends on the length scale that characterises\nthe system, \\emph{viz} the particle diameter.",
        "positive": "Universal $L^{-3}$ finite-size effects in the viscoelasticity of\n  confined amorphous systems: We present a theory of viscoelasticity of amorphous media, which takes into\naccount the effects of confinement along one of three spatial dimensions. The\nframework is based on the nonaffine extension of lattice dynamics to amorphous\nsystems, or nonaffine response theory. The size effects due to the confinement\nare taken into account via the nonaffine part of the shear storage modulus\n$G'$. The nonaffine contribution is written as a sum over modes in $k$-space.\nWith a rigorous argument based on the analysis of the $k$-space integral over\nmodes, it is shown that the confinement size $L$ in one spatial dimension, e.g.\nthe $z$ axis, leads to a infrared cut-off for the modes contributing to the\nnonaffine (softening) correction to the modulus that scales as $L^{-3}$.\nCorrections for finite sample size $D$ in the two perpendicular dimensions\nscale as $\\sim (L/D)^4$, and are negligible for $L \\ll D$. For liquids it is\npredicted that $G'\\sim L^{-3}$ in agreement with a previous more approximate\nanalysis, whereas for amorphous materials $G' \\sim G'_{bulk} + \\beta L^{-3}$.\nFor the case of liquids, four different experimental systems are shown to be\nvery well described by the $L^{-3}$ law."
    },
    {
        "anchor": "Dissipative dynamics of superfluid vortices at non-zero temperatures: We consider the evolution and dissipation of vortex rings in a condensate at\nnon-zero temperature, in the context of the classical field approximation,\nbased on the defocusing nonlinear Schr\\\"odinger equation. The temperature in\nsuch a system is fully determined by the total number density and the number\ndensity of the condensate. A vortex ring is introduced into a condensate in a\nstate of thermal equilibrium, and interacts with non-condensed particles. These\ninteractions lead to a gradual decrease in the vortex line density, until the\nvortex ring completely disappears. We show that the square of the vortex line\nlength changes linearly with time, and obtain the corresponding universal decay\nlaw. We relate this to mutual friction coefficients in the fundamental equation\nof vortex motion in superfluids.",
        "positive": "Magnetization of Planar Four-Fermion Systems: We consider a planar system of fermions, at finite temperature and density,\nunder a static magnetic field parallel to the two-dimensional plane. This\nmagnetic field generates a Zeeman effect and, then, a spin polarization of the\nsystem. The critical properties are studied from the Landau's free energy. The\npossible observable consequences of the magnetization of planar systems such as\npolymer films and graphene are discussed."
    },
    {
        "anchor": "Dynamically controlled double-well optical potential for colloidal\n  particles: This preliminary study presents a simple modulation scheme to dynamically\ncreate time-averaged optical potentials to trap colloidal particles using\nacousto-optical modulation. The method provides access to control\nexperimentally relevant parameters of a tunable double-well potential. We show\nexperimental data successfully adjusting the trapping distance in the range\n20-2000 nm and discuss situations arising when reconstructing time-averaged\noptical potentials from trapped particle data. This is the first step towards\nstudying colloidal particles in dynamically modulated optical potentials to\nexplore the stochastic thermodynamics of mesoscopic systems and small-scale\nthermo-mechanical machines.",
        "positive": "Athermal Activation in Glassy Fluid: In this article, the mechanism of the unexpected high fluidity in SiOx\nnanowire under modest irradiation was proposed, the high fluidity is attributed\nto the long lifetime of irradiation-induced holes, which arise from formation\nof small polarons. The holes created in irradiation could have a long lifetime,\nand localized in space, such missing of bonding electron could suppress the\nenergy barrier(athermal activation effect) for a Pachner move of the network.\nThe atomic level dynamics of the system is proposed by interaction of phonon\nand local configuration, the activation effect was then studied with passing\nrate of corresponding stochastic dynamic equation, calculation shows an\nexponential dependent of the time-lapse of Pachner move to lifetime of the\nactivation, furthermore, connection between the local configuration time and\nviscosity of the fluid indicates a strong sensitivity of viscosity to lifetime\nof the athermal activation, such mechanism would give an effective\ninterpretation to the unexpected high fluidity together with the passivation\neffect of the conductor on the material."
    },
    {
        "anchor": "Quantifying the Reversible Association of Thermosensitive Nanoparticles: Under many conditions, biomolecules and nanoparticles associate by means of\nattractive bonds, due to hydrophobic attraction. Extracting the microscopic\nassociation or dissociation rates from experimental data is complicated by the\ndissociation events and by the sensitivity of the binding force to temperature\n(T). Here we introduce a theoretical model that combined with light-scattering\nexperiments allows us to quantify these rates and the reversible binding energy\nas a function of T. We apply this method to the reversible aggregation of\nthermoresponsive polystyrene/poly(N-isopropylacrylamide) core-shell\nnanoparticles, as a model system for biomolecules. We find that the binding\nenergy changes sharply with T, and relate this remarkable switchable behavior\nto the hydrophobic-hydrophilic transition of the thermosensitive nanoparticles.",
        "positive": "Monte Carlo simulation of defects in hard-sphere crystal grown on a\n  square pattern: Monte Carlo simulations of hard-sphere (HS) crystal grown on a square\npatterned wall under gravity have been performed. While previous simulations\nwere performed with step-wise controlled gravity, in the present simulations\nconstant gravity has been applied from the first. In the case in which a flat\nwall is used as the bottom wall, if a large gravity is suddenly applied, the\nsystem does polycrystallize. On the other hand, in the present simulations,\ndespite the sudden application of gravity, the system has not polycrystallize.\nCrystalline nucleation on the square pattern and successive crystal growth\nupward are suggested to overcome the homogeneous nucleation inside and result\nin. Defect disappearance, which has been essentially the same as that for the\ncase with step-wise controlled gravity, has also observed for the present case.\nThe characteristic of the square patterned bottom wall simulation with a large\nhorizontal system size has been existence of triangular defects suggesting\nstacking tetrahedra."
    },
    {
        "anchor": "Reply to W. T. Kranz on \"Explicit analytical solution for random close\n  packing in $d=2$ and $d=3$\": A recent Comment by W. T. Kranz is shown to be plagued by a serious\nmathematical error which makes its conclusions invalid.",
        "positive": "Beating to rotational transition of a clamped active ribbon-like\n  filament: We present a detailed study of a clamped ribbon-like filament under a\ncompressive active force using Brownian dynamics simulations. We show that a\nclamped ribbon-like filament is able to capture beating as well as a rotational\nmotion under the compressive force. The nature of oscillation is governed by\nthe torsional rigidity of the filament. The frequency of oscillation is almost\nindependent of the torsional rigidity. The beating of the filament gives\nbutterfly shape trajectory of the free-end monomer, whereas rotational motion\nyields a circular trajectory on a plane. The binormal correlation and the\nprincipal component analysis reveal the butterfly, elliptical, and circular\ntrajectories of the free end monomer. We present a phase diagram for different\nkinds of motion in the parameter regime of compressive force and torsional\nrigidity."
    },
    {
        "anchor": "Probing DNA conformational changes with high temporal resolution by\n  Tethered Particle Motion: The Tethered Particle Motion (TPM) technique informs about conformational\nchanges of DNA molecules, e.g. upon looping or interaction with proteins, by\ntracking the Brownian motion of a particle probe tethered to a surface by a\nsingle DNA molecule and detecting changes of its amplitude of movement. We\ndiscuss in this context the time resolution of TPM, which strongly depends on\nthe particle-DNA complex relaxation time, i.e. the characteristic time it takes\nto explore its configuration space by diffusion. By comparing theory,\nsimulations and experiments, we propose a calibration of TPM at the dynamical\nlevel: we analyze how the relaxation time grows with both DNA contour length\n(from 401 to 2080 base pairs) and particle radius (from 20 to 150~nm). Notably\nwe demonstrate that, for a particle of radius 20~nm or less, the hydrodynamic\nfriction induced by the particle and the surface does not significantly slow\ndown the DNA. This enables us to determine the optimal time resolution of TPM\nin distinct experimental contexts which can be as short as 20~ms.",
        "positive": "Critical Casimir forces and colloidal aggregation: A numerical study: We present a numerical study of the effective potential $V_\\mathrm{eff}$\nbetween two hard-sphere colloids dispersed in a solvent of interacting\nparticles, for several values of temperature and solvent density, approaching\nthe solvent gas-liquid critical point. We investigate the stability of a system\nof particles interacting via $V_\\mathrm{eff}$ to evaluate the locus of\ncolloidal aggregation in the solvent phase-diagram, and its dependence on the\ncolloid size. We assess how the excluded volume depletion forces are modified\nby solvent attraction and discuss under which conditions solvent critical\nfluctuations, in the form of critical Casimir forces, can be used to\neffectively manipulate colloidal aggregation."
    },
    {
        "anchor": "An Extreme Toughening Mechanism for Soft Materials: Soft yet tough materials are ubiquitous in nature and everyday life. The\nratio between fracture toughness and intrinsic fracture energy of a soft\nmaterial defines its toughness enhancement. Soft materials' toughness\nenhancement has been long attributed to their bulk stress-stretch hysteresis\ninduced by dissipation mechanisms such as Mullins effect and viscoelasticity.\nWith a combination of experiments and theory, here we show that the bulk\ndissipation mechanisms significantly underestimate the toughness enhancement of\nsoft tough materials. We propose a new mechanism and scaling law to account for\nthe extreme toughening of diverse soft materials. We show that the toughness\nenhancement of soft materials relies on both bulk hysteric dissipation, and\nnear-crack dissipation due to mechanisms such as polymer-chain entanglement.\nUnlike the bulk hysteric dissipation, the near-crack dissipation does not\nnecessarily induce large stress-stretch hysteresis of the bulk material. The\nextreme toughening mechanism can be universally applied to various soft tough\nmaterials, ranging from double-network hydrogels, interpenetrating-network\nhydrogels, entangled-network hydrogels and slide-ring hydrogels, to unfilled\nand filled rubbers.",
        "positive": "Ginzburg-Landau theory of polar nematic monolayers: This paper has been withdrawn by the author due to the need for further\nrevision."
    },
    {
        "anchor": "Active cage model of glassy dynamics: We build up a phenomenological picture in terms of the effective dynamics of\na tracer confined in a cage experiencing random hops to capture somec\nharacteristics of glassy systems. This minimal description exhibits scale\ninvariance properties for the small-displacement distribution that echo\nexperimental observations. We predict the existence of exponential tails as a\ncross-over between two Gaussian regimes. Moreover, we demonstrate that the\nonset of glassy behavior is controlled only by two dimensionless numbers: the\nnumber of hops occurring during the relaxation of the particle within a local\ncage, and the ratio of the hopping length to the cage size.",
        "positive": "The probability analysis of opening of DNA: We have studied the separation of a double stranded DNA (dsDNA), which is\ndriven either by the temperature or force. By monitoring the probability of\nopening of entire base pairs along the chain, we show that the opening of a\ndsDNA depends not only on the sequence but also on the constraints on the chain\nin the experimental setups. Our results clearly demonstrate that the force\ninduced melting of dsDNA, whose one of the ends is constrained, is\nsignificantly different from the thermal melting, when both ends free."
    },
    {
        "anchor": "The Excess Wing in the Dielectric Loss of Glass-Formers: A\n  Johari-Goldstein beta-Relaxation?: Dielectric loss spectra of glass-forming propylene carbonate and glycerol at\ntemperatures above and below T_g are presented. By performing aging experiments\nlasting up to five weeks, equilibrium spectra below T_g have been obtained.\nDuring aging, the excess wing, showing up as a second power law at high\nfrequencies, develops into a shoulder. The results strongly suggest that the\nexcess wing, observed in a variety of glass formers, is the high-frequency\nflank of a beta-relaxation.",
        "positive": "Induced stresses in quasi-spherical elastic vesicles: local and global\n  Laplace-Young law: On elastic spherical membranes, there is no stress induced by the bending\nenergy and the corresponding Laplace-Young law does not involve the elastic\nbending stiffness. However, when considering an axially symmetrical\nperturbation that pinches the sphere, it induces nontrivial stresses on the\nentire membrane. In this paper we introduce a theoretical framework to examine\nthe stress induced by perturbations of geometry around the sphere. We find the\nlocal balance force equations along the normal direction to the vesicle, and\nalong the unit binormal, tangent to the membrane; likewise, the global balance\nforce equation on closed loops is also examined. We analyze the distribution of\nstresses on the membrane as the budding transition occurs. For closed membranes\nwe obtain the modified Young-Laplace law that appears as a consequence of this\nperturbation."
    },
    {
        "anchor": "Modeling the isotropic/smectic-C tilted lamellar liquid crystalline\n  transition: Extensions of a previously presented Landau-de Gennes type liquid crystalline\nphase transition model for the direct isotropic/smectic-A (lamellar) a phase\ntransition to the direct isotropic/smectic-C (tilted lamellar) transition are\nstudied. Two different proposed extensions to the model are studied both in the\ncontext of ideal ordering (point volume) and full three-dimensional uniaxial\nscalar/vector decomposition. Recommendations based upon the inclusion of\nessential physics and computational feasibility are made, distinguishing each\nof the two proposed extensions based upon these criteria. Additionally, it is\nfound that the approach used for the isotropic/smectic-A model to\ndeterministically compute phase diagram data is not possible for either of the\ntwo proposed isotropic/smectic-C models.",
        "positive": "The Influence of Motility on Bacterial Accumulation in a Microporous\n  Channel: We study the transport of bacteria in a porous media modeled by a square\nchannel containing one cylindrical obstacle via molecular dynamics simulations\ncoupled to a lattice Boltzmann fluid. Our bacteria model is a rod-shaped rigid\nbody which is propelled by a force-free mechanism. To account for the behavior\nof living bacteria, the model also incorporates a run-and-tumble process. The\nmodel bacteria are capable of hydrodynamically interacting with both of the\nchannel walls and the obstacle. This enables the bacteria to get reoriented\nwhen experiencing a shear-flow. We demonstrate that this model is capable of\nreproducing the bacterial accumulation on the rear side of an obstacle, as has\nrecently been experimentally observed by [G. L. Mino, et al., Advances in\nMicrobiology 8, 451 (2018)] using E.coli bacteria. By systematically varying\nthe external flow strength and the motility of the bacteria, we resolve the\ninterplay between the local flow strength and the swimming characteristics that\nlead to the accumulation. Moreover, by changing the geometry of the channel, we\nalso reveal the important role of the interactions between the bacteria and the\nconfining walls for the accumulation process."
    },
    {
        "anchor": "Effect of Composition Changes on the Structural Relaxation of a Binary\n  Mixture: Within the mode-coupling theory for idealized glass transitions, we study the\nevolution of structural relaxation in binary mixtures of hard spheres with size\nratios $\\delta$ of the two components varying between 0.5 and 1.0. We find two\nscenarios for the glassy dynamics. For small size disparity, the mixing yields\na slight extension of the glass regime. For larger size disparity, a\nplasticization effect is obtained, leading to a stabilization of the liquid due\nto mixing. For all $\\delta$, a decrease of the elastic moduli at the transition\ndue to mixing is predicted. A stiffening of the glass structure is found as is\nreflected by the increase of the Debye-Waller factors at the transition points.\nThe critical amplitudes for density fluctuations at small and intermediate wave\nvectors decrease upon mixing, and thus the universal formulas for the\nrelaxation near the plateau values describe a slowing down of the dynamics upon\nmixing for the first step of the two-step relaxation scenario. The results\nexplain the qualitative features of mixing effects reported by Williams and van\nMegen [Phys. Rev. E \\textbf{64}, 041502 (2001)] for dynamical light-scattering\nmeasurements on binary mixtures of hard-sphere-like colloids with size ratio\n$\\delta=0.6$.",
        "positive": "Long-term memory and delayed shear localisation in soft glassy materials: We study theoretically the dynamics of soft glassy materials during the\nprocess of stress relaxation following the rapid imposition of a shear strain.\nBy detailed numerical simulations of a mesoscopic soft glassy rheology model\nand three different simplified continuum fluidity models, we show that a\ndramatic shear localisation instability arises, in which the strain field\nsuddenly becomes heterogeneous within the sample, accompanied by a precipitous\ndrop in the stress. Remarkably, this instability can arise at extremely long\ndelay times after the strain was applied, due to the long-term memory inherent\nto glassy systems. The finding that a catastrophic mechanical instability can\narise long after any deformation could have far reaching consequences for\nmaterial processing and performance, and potentially also for delayed\ngeophysical phenomena."
    },
    {
        "anchor": "Pattern formation and phase transitions in systems with non-monotonic\n  interaction: We analyzed pattern formation and identified different phases in a system of\nparticles interacting through a non-monotonic short-range repulsive (r<r_c) and\nlong-range attractive (r>r_c) potential, using molecular-dynamics simulations.\nDepending on parameters, the interaction potential models the interparticle\ninteraction in various physical systems ranging from atoms, molecules and\ncolloids to neutron stars and vortices in low-kappa type-II superconductors and\nin recently discovered \"type-1.5\" superconductors. We constructed the phase\ndiagram \"critical radius r_c - density n\" and proposed a new approach to\ncharacterization of the phases. Namely, we elaborated a set of quantitative\ncriteria in order to identify the different phases using the Radial\nDistribution Function (RDF), the local density function, and the occupation\nfactor.",
        "positive": "Phototaxis of synthetic microswimmers in optical landscapes: Many microorganisms, with phytoplankton and zooplankton as prominent\nexamples, display phototactic behaviour, that is, the ability to perform\ndirected motion within a light gradient. Here we experimentally demonstrate\nthat sensing of light gradients can also be achieved in a system of synthetic\nphoto-activated microparticles being exposed to an inhomogeneous laser field.\nWe observe a strong orientational response of the particles because of\ndiffusiophoretic torques, which in combination with an intensity-dependent\nparticle motility eventually leads to phototaxis. Since the aligning torques\nsaturate at high gradients, a strongly rectified particle motion is found even\nin periodic asymmetric intensity landscapes. Our results are in excellent\nagreement with numerical simulations of a minimal model and should similarly\napply to other particle propulsion mechanisms. Because light fields can be\neasily adjusted in space and time, this also allows to extend our approach to\ndynamical environments."
    },
    {
        "anchor": "The Information Capacity of Specific Interactions: Specific interactions are a hallmark feature of self-assembly and\nsignal-processing systems in both synthetic and biological settings.\nSpecificity between components may arise from a wide variety of physical and\nchemical mechanisms in diverse contexts, from DNA hybridization to\nshape-sensitive depletion interactions. Despite this diversity, all systems\nthat rely on interaction specificity operate under the constraint that\nincreasing the number of distinct components inevitably increases off-target\nbinding. Here we introduce `capacity', the maximal information encodable using\nspecific interactions, to compare specificity across diverse experimental\nsystems, and to compute how specificity changes with physical parameters. Using\nthis framework, we find that `shape'-coding of interactions has higher capacity\nthan chemical (`color') coding because the strength of off-target binding is\nstrongly sublinear in binding site size for shapes while being linear for\ncolors. We also find that different specificity mechanisms, such as shape and\ncolor, can be combined in a synergistic manner, giving a capacity greater than\nthe sum of the parts.",
        "positive": "Lifetimes and Lengthscales of Structural Motifs in a Model Glassformer: We use a newly-developed method to identify local structural motifs in a\npopular model glassformer, the Kob-Andersen binary Lennard-Jones mixture. By\nmeasuring the lifetimes of a zoo of clusters, we find that 11-membered bicapped\nsquare antiprisms, denoted as 11A, have longer lifetimes on average than other\nstructures considered. Other long-lived clusters are similar in structure to\nthe 11A cluster. These clusters group into ramified networks that are\ncorrelated with slow particles and act to retard the motion of neighbouring\nparticles. The structural lengthscale associated with these networks does not\ngrow as fast as the dynamical lengthscale $\\xi_4$ as the system is cooled, in\nthe range of temperatures our molecular dynamics simulations access. Thus we\nfind a strong, but indirect, correlation between static structural ordering and\nslow dynamics."
    },
    {
        "anchor": "Aggregation of colloidal nanoparticles in polymer matrices: Some of our recent studies of the structure and mechanical properties of a\nspecial type of nanocomposite are reviewed here. In silica-latex systems, a\nlatex film with silica inclusions is formed from a colloidal solution of both\ncomponents. During drying of the solution, the formation of silica domains can\nbe controlled via the physico-chemical properties of the solution. Well-defined\nsilica aggregates embedded in a polymer matrix can be generated, and the\nmechanical properties of the resulting nanocomposite have been shown to be\ndirectly correlated to the average structure.",
        "positive": "Phase separation in binary colloids with charge asymmetry: We report that binary dispersions of like-charged colloidal particles with\nlarge charge asymmetry but similar size exhibit phase separation into crystal\nand fluid phases under very low salt conditions. This is unexpected because the\neffective colloid-colloid pair interactions are accurately described by a\nYukawa model which is stable to demixing. We show that colloid-ion interactions\nprovide an energetic driving force for phase separation, which is initiated by\ncrystallization of one species."
    },
    {
        "anchor": "Dynamic buckling of an inextensible elastic ring: Linear and nonlinear\n  analyses: Slender elastic objects such as a column tend to buckle under loads. While\nstatic buckling is well understood as a bifurcation problem, the evolution of\nshapes during dynamic buckling is much harder to study. Elastic rings under\nnormal pressure have emerged as a theoretical and experimental paradigm for the\nstudy of dynamic buckling with controlled loads. Experimentally, an elastic\nring is placed within a soap film. When the film outside the ring is removed,\nsurface tension pulls the ring inward, mimicking an external pressurization.\nHere we present a theoretical analysis of this process by performing a\npost-bifurcation analysis of an elastic ring under pressure. This analysis\nallows us to understand how inertia, material properties, and loading affect\nthe observed shape. In particular, we combine direct numerical solutions with a\npost-bifurcation asymptotic analysis to show that inertia drives the system\ntowards higher modes that cannot be selected in static buckling. Our\ntheoretical results explain experimental observations that cannot be captured\nby a standard linear stability analysis.",
        "positive": "Finite-Size Scaling at the Jamming Transition: We present an analysis of finite-size effects in jammed packings of N soft,\nfrictionless spheres at zero temperature. There is a 1/N correction to the\ndiscrete jump in the contact number at the transition so that jammed packings\nexist only above isostaticity. As a result, the canonical power-law scalings of\nthe contact number and elastic moduli break down at low pressure. These\nquantities exhibit scaling collapse with a non-trivial scaling function,\ndemonstrating that the jamming transition can be considered a phase transition.\nScaling is achieved as a function of N in both 2 and 3 dimensions, indicating\nan upper critical dimension of 2."
    },
    {
        "anchor": "Origin of the extremely high elasticity of bulk emulsions, stabilized by\n  Yucca Schidigera saponins: We found experimentally that the elasticity of sunflower oil-in-water\nemulsions (SFO-in-W) stabilized by Yucca Schidigera Roezl saponin extract, is\nby more than 50 times higher as compared to the elasticity of common emulsions.\nWe revealed that strong specific interactions between the phytosterols from the\nnon-purified oil and the saponins from the Yucca extract lead to the formation\nof nanostructured adsorption layers which are responsible for the very high\nelasticity of the oil-water interface and of the respective bulk emulsions.\nRemarkably, this extra high emulsion elasticity inhibits the emulsion syneresis\neven at 65 vol % of the oil drops. These emulsions remain homogeneous and\nstable even after 30 days of shelf-storage. These results demonstrate that the\ncombination of saponin and phytosterols is a powerful new approach to structure\noil-in-water emulsions with potential applications for formulating healthier\nfunctional food.",
        "positive": "Colloidal electro-phoresis in the presence of symmetric and asymmetric\n  electro-osmotic flow: We characterize the electro-phoretic motion of charged sphere suspensions in\nthe presence of substantial electro-osmotic flow using a recently introduced\nsmall angle super-heterodyne dynamic light scattering instrument (ISASH-LDV).\nOperation in integral mode gives access to the particle velocity distribution\nover the complete cell cross-section. Obtained Doppler spectra are evaluated\nfor electro-phoretic mobility, wall electro-osmotic mobility and particle\ndiffusion coefficient. Simultaneous measurements of differing electro-osmotic\nmobilities leading to asymmetric solvent flow are demonstrated in a custom made\nelectro-kinetic cell fitting standard microscopy slides as exchangeable\nsidewalls. Scope and range of our approach are discussed demonstrating the\npossibility of an internal calibration standard and using the simultaneously\nmeasured electro-kinetic mobilities in the interpretation of microfluidic\npumping experiment involving an inhomogeneous electric field and a complex\nsolvent flow pattern."
    },
    {
        "anchor": "Effects of Translation-Rotation Coupling on the Displacement Probability\n  Distribution Functions of Boomerang Colloidal Particles: Prior studies have shown that low symmetry particles such as micro-boomerangs\nexhibit behaviour of Brownian motion rather different from that of high\nsymmetry particles because convenient tracking points (TPs) are usually\ninconsistent with the center of hydrodynamic stress (CoH) where the\ntranslational and rotational motions are decoupled. In this paper we study the\neffects of the translation-rotation coupling on the displacement probability\ndistribution functions (PDFs) of the boomerang colloid particles with symmetric\narms. By tracking the motions of different points on the particle symmetry\naxis, we show that as the distance between the TP and the CoH is increased, the\neffects of translation-rotation coupling becomes pronounced, making the\nshort-time 2D PDF for fixed initial orientation to change from elliptical to\ncrescent shape and the angle averaged PDFs from ellipsoidal-particle-like PDF\nto a shape with a Gaussian top and long displacement tails. We also observed\nthat at long times the PDFs revert to Gaussian. This crescent shape of 2D PDF\nprovides a clear physical picture of the non-zero mean displacements observed\nin boomerangs particles.",
        "positive": "The interplay between hydrodynamic and Brownian fluctuations in\n  sedimenting colloidal suspensions: We apply a hybrid Molecular Dynamics and mesoscopic simulation technique to\nstudy the steady-state sedimentation of hard sphere particles for Peclet\nnumbers (Pe) ranging from 0.08 to 12. Hydrodynamic back-flow causes a reduction\nof the average sedimentation velocity relative to the Stokes velocity. We find\nthat this effect is independent of Pe number. Velocity fluctuations show the\nexpected effects of thermal fluctuations at short correlation times. At longer\ntimes, non-equilibrium hydrodynamic fluctuations are visible, and their\ncharacter appears to be independent of the thermal fluctuations. The\nhydrodynamic fluctuations dominate the diffusive behavior even for modest Pe\nnumber, while conversely the short-time fluctuations are dominated by thermal\neffects for a surprisingly large Pe numbers. Inspired by recent experiments, we\nalso study finite sedimentation in a horizontal planar slit. In our simulations\ndistinct lateral patterns emerge, in agreement with observations in the\nexperiments."
    },
    {
        "anchor": "Surface-Directed Spinodal Decomposition on Chemically Patterned\n  Substrates: {\\it Surface-directed spinodal decomposition} (SDSD) is the kinetic interplay\nof phase separation and wetting at a surface. This process is of great\nscientific and technological importance. In this paper, we report results from\na numerical study of SDSD on a chemically patterned substrate. We consider\nsimple surface patterns for our simulations, but most of the results apply for\narbitrary patterns. In layers near the surface, we observe a dynamical\ncrossover from a {\\it surface-registry regime} to a {\\it phase-separation\nregime}. We study this crossover using layer-wise correlation functions and\nstructure factors, and domain length scales.",
        "positive": "Effective charge and free energy of DNA inside an ion channel: Translocation of a single stranded DNA (ssDNA) through an alpha-hemolysin\nchannel in a lipid membrane driven by applied transmembrane voltage V was\nextensively studied recently. While the bare charge of the ssDNA piece inside\nthe channel is approximately 12 (in units of electron charge) measurements of\ndifferent effective charges resulted in values between one and two. We explain\nthese challenging observations by a large self-energy of a charge in the narrow\nwater filled gap between ssDNA and channel walls, related to large difference\nbetween dielectric constants of water and lipid, and calculate effective\ncharges of ssDNA. We start from the most fundamental stall charge $q_s$, which\ndetermines the force $F_s= q_s V/L$ stalling DNA against the voltage V (L is\nthe length of the channel). We show that the stall charge $q_s$ is proportional\nto the ion current blocked by DNA, which is small due to the self-energy\nbarrier. Large voltage V reduces the capture barrier which DNA molecule should\novercome in order to enter the channel by $|q_c|V$, where $q_c$ is the\neffective capture charge. We expressed it through the stall charge $q_s$. We\nalso relate the stall charge $q_s$ to two other effective charges measured for\nssDNA with a hairpin in the back end: the charge $q_u$ responsible for\nreduction of the barrier for unzipping of the hairpin and the charge $q_e$\nresponsible for DNA escape in the direction of hairpin against the voltage. At\nsmall V we explain reduction of the capture barrier with the salt\nconcentration."
    },
    {
        "anchor": "Modelling the formation of structured deposits at receding contact lines\n  of evaporating solutions and suspensions: When a film of a liquid suspension of nanoparticles or a polymer solution is\ndeposited on a surface, it may dewet from the surface and as the solvent\nevaporates the solute particles/polymer can be deposited on the surface in\nregular line patterns. In this paper we explore a hydrodynamic model for the\nprocess that is based on a long-wave approximation that predicts the deposition\nof irregular and regular line patterns. This is due to a self-organised\npinning-depinning cycle that resembles a stick-slip motion of the contact line.\nWe present a detailed analysis of how the line pattern properties depend on\nquantities such as the evaporation rate, the solute concentration, the P\\'eclet\nnumber, the chemical potential of the ambient vapour, the disjoining pressure,\nand the intrinsic viscosity. The results are related to several experiments and\nto depinning transitions in other soft matter systems.",
        "positive": "Elastic Properties of Liquid Surfaces Coated with Colloidal Particles: The physical mechanism of elasticity of liquid surfaces coated with colloidal\nparticles is proposed. It is suggested that particles are separated by water\nclearings and the capillary interaction between them is negligible. The case is\ntreated when the colloidal layer is deformed normally to its surface. The\nelasticity arises as an interfacial effect. The effective Young modulus of a\nsurface depends on the interfacial tension, equilibrium contact angle, radius\nof colloidal particles and their surface density. For the nanometrically scaled\nparticles the line tension becomes essential and has an influence on the\neffective Young modulus."
    },
    {
        "anchor": "Elastic capsules in shear flow: Analytical solutions for constant and\n  time-dependent shear rates: We investigate the dynamics of microcapsules in linear shear flow within a\nreduced model with two degrees of freedom. In previous work for steady shear\nflow, the dynamic phases of this model, i.e. swinging, tumbling and\nintermittent behaviour, have been identified using numerical methods. In this\npaper, we integrate the equations of motion in the quasi-spherical limit\nanalytically for time-constant and time-dependent shear flow using matched\nasymptotic expansions. Using this method, we find analytical expressions for\nthe mean tumbling rate in general time-dependent shear flow. The capsule\ndynamics is studied in more detail when the inverse shear rate is harmonically\nmodulated around a constant mean value for which a dynamic phase diagram is\nconstructed. By a judicious choice of both modulation frequency and phase,\ntumbling motion can be induced even if the mean shear rate corresponds to the\nswinging regime. We derive expressions for the amplitude and width of the\nresonance peaks as a function of the modulation frequency.",
        "positive": "Polar active liquids: a universal classification rooted in\n  nonconservation of momentum: We study the spatially homogeneous phases of polar active particles in the\nlow density limit, and specifically the transition from the isotropic phase to\ncollective polar motion. We show that the fundamental quantity of interest for\nthe stability of the isotropic phase is the forward component of the momentum\nchange induced by binary scattering events. Building on the Boltzmann\nformalism, we introduce an ansatz for the one-particle distribution and derive\na closed-form evolution equation for the order parameter. This approach yields\na very intuitive and physically meaningful criterion for the destabilization of\nthe isotropic phase, where the ansatz is exact. The criterion also predicts\nwhether the transition is continuous or discontinuous, as illustrated in three\ndifferent classes of models. The theoretical predictions are in excellent\nagreement with numerical results."
    },
    {
        "anchor": "An Infinite Set of Integral Formulae for Polar, Nematic, and Higher\n  Order Structures at the Interface of Motility-Induced Phase Separation: Motility-induced phase separation (MIPS) is a purely non-equilibrium\nphenomenon in which self-propelled particles phase separate without any\nattractive interactions. One surprising feature of MIPS is the emergence of\npolar, nematic, and higher order structures at the interfacial region, whose\nunderlying physics remains poorly understood. Starting with a model of MIPS in\nwhich all many-body interactions are captured by an effective speed function\nand an effective pressure function that depend solely on the local particle\ndensity, I derive analytically an infinite set of integral formulae (IF) for\nthe ordering structures at the interface. I then demonstrate that half of these\nIF are in fact exact for a wide class of active Brownian particle systems.\nFinally, I test the IF by applying them to numerical data from direct particle\ndynamics simulation and find that all the IF remain valid to a great extent.",
        "positive": "Stochastic Eulerian Lagrangian Methods for Fluid-Structure Interactions\n  with Thermal Fluctuations: We present approaches for the study of fluid-structure interactions subject\nto thermal fluctuations. A mixed mechanical description is utilized combining\nEulerian and Lagrangian reference frames. We establish general conditions for\noperators coupling these descriptions. Stochastic driving fields for the\nformalism are derived using principles from statistical mechanics. The\nstochastic differential equations of the formalism are found to exhibit\nsignificant stiffness in some physical regimes. To cope with this issue, we\nderive reduced stochastic differential equations for several physical regimes.\nWe also present stochastic numerical methods for each regime to approximate the\nfluid-structure dynamics and to generate efficiently the required stochastic\ndriving fields. To validate the methodology in each regime, we perform analysis\nof the invariant probability distribution of the stochastic dynamics of the\nfluid-structure formalism. We compare this analysis with results from\nstatistical mechanics. To further demonstrate the applicability of the\nmethodology, we perform computational studies for spherical particles having\ntranslational and rotational degrees of freedom. We compare these studies with\nresults from fluid mechanics. The presented approach provides for\nfluid-structure systems a set of rather general computational methods for\ntreating consistently structure mechanics, hydrodynamic coupling, and thermal\nfluctuations."
    },
    {
        "anchor": "Dynamics of Active Polar Ring Polymers: The conformational and dynamical properties of isolated semiflexible active\npolar ring polymers are investigated analytically. A ring is modeled as\ncontinuous Gaussian polymer exposed to tangential active forces. The analytical\nsolution of the linear non-Hermitian equation of motion in terms of an\neigenfunction expansion shows that ring conformations are independent of\nactivity. In contrast, activity strongly affects the internal ring dynamics and\nyields characteristic time regimes, which are absent in passive rings. On\nintermediate time scales, flexible rings show an activity-enhanced diffusive\nregime, while semiflexible rings exhibit ballistic motion. Moreover, a second\nactive time regime emerges on longer time scales, where rings display a\nsnake-like motion, which is reminiscent to a tank-treading rotational dynamics\nin shear flow, dominated by the mode with the longest relaxation time.",
        "positive": "A Model of Electrowetting, Reversed Electrowetting and Contact Angle\n  Saturation: While electrowetting has many applications, it is limited at large voltages\nby contact angle saturation - a phenomenon that is still not well understood.\nWe propose a generalized approach for electrowetting that, among other results,\ncan shed new light on contact angle saturation. The model assumes the existence\nof a minimum (with respect to the contact angle) in the electric energy and\naccounts for a quadratic voltage dependence ~U^2 in the low-voltage limit,\ncompatible with the Young-Lippmann formula, and a ~1/U^2 saturation at the\nhigh-voltage limit. Another prediction is the surprising possibility of a\nreversed electrowetting regime, in which the contact angle increases with\napplied voltage. By explicitly taking into account the effect of the\ncounter-electrode, our model is shown to be applicable to several AC and DC\nexperimental electrowetting-on-dielectric (EWOD) setups. Several features seen\nin experiments compare favorably with our results. Furthermore, the AC\nfrequency dependence of EWOD agrees quantitatively with our predictions. Our\nnumerical results are complemented with simple analytical expressions for the\nsaturation angle in two practical limits."
    },
    {
        "anchor": "Time-resolved X-ray microscopy of nanoparticle aggregates under\n  oscillatory shear: Of all current detection techniques with nanometer resolution, only X-ray\nmicroscopy allows imaging nanoparticles in suspension. Can it also be used to\ninvestigate structural dynamics? When studying response to mechanical stimuli,\nthe challenge lies in applying them with precision comparable to spatial\nresolution. In the first shear experiments performed in an X-ray microscope, we\naccomplished this by inserting a piezo actuator driven shear cell into the\nfocal plane of a scanning transmission X-ray microscope (STXM). Thus\nshear-induced reorganization of magnetite nanoparticle aggregates could be\ndemonstrated in suspension. As X-ray microscopy proves suitable for studying\nstructural change, new prospects open up in physics at small length scales.",
        "positive": "Viscosity ratio across interfaces controls the stability and\n  self-assembly of microrollers: We investigate the individual and collective dynamics of torque-driven\nparticles, called microrollers, near fluid-fluid interfaces. We find that the\nviscosity ratio across the interface controls the speed and direction of the\nparticles, their relative motion, the growth of a fingering instability, and\nthe self-assembled motile structures that emerge from it. By combining theory\nand large scale numerical simulations, we show how the viscosity ratio across\nthe interface governs the long-range hydrodynamic interactions between\nparticles and thus their collective behavior."
    },
    {
        "anchor": "Unfolding Collapsed Polyelectrolytes in Alternating-Current Electric\n  Fields: We investigate the unfolding of single polyelectrolyte (PE) chains collapsed\nby trivalent salt under the action of alternating-current (AC) electric fields\nthrough computer simulations and theoretical scaling. The results show that a\ncollapsed chain can be unfolded by an AC field when the field strength exceeds\nthe direct-current (DC) threshold and the frequency is below a critical value,\ncorresponding to the inverse charge relaxation/dissociation time of condensed\ntrivalent counterions at the interface of the collapsed electrolyte. This\nrelaxation time is also shown to be identical to the DC chain fluctuation time,\nsuggesting that the dissociation of condensed polyvalent counterion on the\ncollapsed PE interface controls the polyelectrolyte dipole formation and\nunfolding dynamics under an AC electric field.",
        "positive": "Novel Phases and Reentrant Melting of Two Dimensional Colloidal Crystals: We investigate two-dimensional (2d) melting in the presence of a\none-dimensional (1d) periodic potential as, for example, realized in recent\nexperiments on 2d colloids subjected to two interfering laser beams. The\ntopology of the phase diagram is found to depend primarily on two factors: the\nrelative orientation of the 2d crystal and the periodic potential troughs,\nwhich select a set of Bragg planes running parallel to the troughs, and the\ncommensurability ratio p= a'/d of the spacing a' between these Bragg planes to\nthe period d of the periodic potential. The complexity of the phase diagram\nincreases with the magnitude of the commensurabilty ratio p. Rich phase\ndiagram, with ``modulated liquid'', ``floating'' and ``locked floating'' solid\nand smectic phases are found. Phase transitions between these phases fall into\ntwo broad universality classes, roughening and melting, driven by the\nproliferation of discommensuration walls and dislocations, respectively. We\ndiscuss correlation functions and the static structure factor in these phases\nand make detailed predictions of the universal features close to the phase\nboundaries. We predict that for charged systems with highly screened\nshort-range interactions these melting transitions are generically reentrant as\na function of the strength of the periodic potential, prediction that is in\naccord with recent 2d colloid experiments. Implications of our results for\nfuture experiments are also discussed."
    },
    {
        "anchor": "Contact of a spherical probe with a stretched rubber substrate: We report on a theoretical and experimental investigation of the normal\ncontact of stretched neo-Hookean substrates with rigid spherical probes.\nStarting from a published formulation of surface Green's function for\nincremental displacements on a pre-stretched, neo-Hookean, substrate (L.H. Lee\n\\textit{J. Mech. Phys. Sol.} \\textbf{56} (2008) 2957-2971), a model is derived\nfor both adhesive and non-adhesive contacts. The shape of the elliptical\ncontact area together with the contact load and the contact stiffness are\npredicted as a function of the in-plane stretch ratios $\\lambda_x$ and\n$\\lambda_y$ of the substrate. The validity of this model is assessed by contact\nexperiments carried out using an uniaxally stretched silicone rubber. for\nstretch ratio below about 1.25, a good agreement is observed between theory and\nexperiments. Above this threshold, some deviations from the theoretical\nprediction are induced as a result of the departure of the mechanical response\nof the silicone rubber from the neo-Hokeean description embedded in the model.",
        "positive": "Substrate Specificity of Peptide Adsorption: A Model Study: Applying the contact density chain-growth algorithm to lattice\nheteropolymers, we identify the conformational transitions of a nongrafted\nhydrophobic-polar heteropolymer with 103 residues in the vicinity of a polar, a\nhydrophobic, and a uniformly attractive substrate. Introducing only two system\nparameters, the numbers of surface contacts and intrinsic hydrophobic contacts,\nrespectively, we obtain surprisingly complex temperature and solvent dependent,\nsubstrate-specific pseudo-phase diagrams."
    },
    {
        "anchor": "Shear banding, discontinuous shear thickening, and rheological phase\n  transitions in athermally sheared frictionless disks: We report on numerical simulations of simple models of athermal, bidisperse,\nsoft-core, massive disks in two dimensions, as a function of packing fraction\n$\\phi$, inelasticity of collisions as measured by a parameter $Q$, and applied\nuniform shear strain rate $\\dot\\gamma$. Our particles have contact interactions\nconsisting of normally directed elastic repulsion and viscous dissipation, as\nwell as tangentially directed viscous dissipation, but no inter-particle\nCoulombic friction. Mapping the phase diagram in the $(\\phi,Q)$ plane for small\n$\\dot\\gamma$, we find a sharp first-order rheological phase transition from a\nregion with Bagnoldian rheology to a region with Newtonian rheology, and show\nthat the system is always Newtonian at jamming. We consider the rotational\nmotion of particles and demonstrate the crucial importance that the coupling\nbetween rotational and translational degrees of freedom has on the phase\nstructure at small $Q$ (strongly inelastic collisions). At small $Q$ we show\nthat, upon increasing $\\dot\\gamma$, the sharp Bagnoldian-to-Newtonian\ntransition becomes a coexistence region of finite width in the\n$(\\phi,\\dot\\gamma)$ plane, with coexisting Bagnoldian and Newtonian shear\nbands. Crossing this coexistence region by increasing $\\dot\\gamma$ at fixed\n$\\phi$, we find that discontinuous shear thickening can result if $\\dot\\gamma$\nis varied too rapidly for the system to relax to the shear-banded steady state\ncorresponding to the instantaneous value of $\\dot\\gamma$.",
        "positive": "Melting a stretched DNA: We study the melting of a double stranded DNA in the presence of stretching\nforces, via 3D Monte-Carlo simulations, exactly solvable models and heuristic\narguments. The resulting force-temperature phase diagram is dramatically\ndifferent for the cases where the force is applied to only one strand or to\nboth. Different assumptions on the monomer size of single and double stranded\nDNA lead to opposite conclusions as to whether DNA melts or not as it\noverstretches."
    },
    {
        "anchor": "Soft Interaction Between Dissolved Dendrimers: Theory and Experiment: Using small-angle neutron scattering and liquid integral equation theory, we\nrelate the structure factor of flexible dendrimers of 4th generation to their\naverage shape. The shape is measured as a radial density profile of monomers\nbelonging to a single dendrimer. From that, we derive an effective interaction\nof Gaussian form between pairs of dendrimers and compute the structure factor\nusing the hypernetted chain approximation. Excellent agreement with the\ncorresponding experimental results is obtained, without the use of adjustable\nparameters. The present analysis thus strongly supports the previous finding\nthat flexible dendrimers of low generation present fluctuating structures akin\nto star polymers.",
        "positive": "The analytical solution to the migration of an epithelial monolayer with\n  a circular spreading front and its implications in the gap closure process: The coordinated behaviors of epithelial cells are widely observed in tissue\ndevelopment, such as re-epithelialization, tumor growth, and morphogenesis. In\nthese processes, cells either migrate collectively or organize themselves into\nspecific structures to serve certain purposes. In this work, we study a\nspreading epithelial monolayer whose migrating front encloses a circular gap in\nthe monolayer center. Such tissue is usually used to mimic the wound healing\nprocess in Virto. We model the epithelial sheet as a layer of active viscous\npolar fluid. With an axisymmetric assumption, the model can be analytically\nsolved under two special conditions, suggesting two possible spreading modes\nfor the epithelial monolayer. Based on these two sets of analytical solutions,\nwe assess the velocity of the spreading front affected by the gap size, the\nactive intercellular contractility, and the purse-string contraction acting on\nthe spreading edge. Several critical values exist in the model parameters for\nthe initiation of the gap closure process, and the purse-string contraction\nplays a vital role in governing the gap closure kinetics. Finally, the\ninstability of the morphology of the spreading front was studied. Numerical\ncalculations show how the perturbated velocities and the growth rates vary with\nrespect to different model parameters."
    },
    {
        "anchor": "Controlling cargo trafficking in multicomponent membranes: Biological membranes typically contain a large number of different components\ndispersed in small concentrations in the main membrane phase, including\nproteins, sugars, and lipids of varying geometrical properties. Most of these\ncomponents do not bind the cargo. Here, we show that such `inert' components\ncan be crucial for precise control of cross-membrane trafficking. Using a\nstatistical mechanics model and molecular dynamics simulations, we demonstrate\nthat the presence of inert membrane components of small isotropic curvatures\ndramatically influences cargo endocytosis, even if the total spontaneous\ncurvature of such a membrane remains unchanged. Curved lipids, such as\ncholesterol, as well as asymmetrically included proteins and tethered sugars\ncan hence all be actively participating in controlling membrane trafficking of\nnanoscopic cargo. We find that even a low-level expression of curved inert\nmembrane components can determine the membrane selectivity towards the cargo\nsize, and can be used to selectively target membranes of certain compositions.\nOur results suggest a robust and general way to control cargo trafficking by\nadjusting the membrane composition without needing to alter the concentration\nof receptors nor the average membrane curvature. This study indicates that\ncells can prepare for any trafficking event by incorporating curved inert\ncomponents in either of the membrane leaflets.",
        "positive": "Glassy dynamics in thin films of polystyrene: Glassy dynamics was investigated for thin films of atactic polystyrene by\ncomplex electric capacitance measurements using dielectric relaxation\nspectroscopy. During the isothermal aging process the real part of the electric\ncapacitance increased with time, whereas the imaginary part decreased with\ntime. It follows that the aging time dependences of real and imaginary parts of\nthe electric capacitance were primarily associated with change in volume (film\nthickness) and dielectric permittivity, respectively. Further, dielectric\npermittivity showed memory and rejuvenation effects in a similar manner to\nthose observed for poly(methyl methacrylate) thin films. On the other hand,\nvolume did not show a strong rejuvenation effect."
    },
    {
        "anchor": "General theory of the viscosity of liquids and solids from nonaffine\n  particle motions: A new microscopic formula for the viscosity of liquids and solids is derived\nrigorously from a first-principles (microscopically reversible) Hamiltonian for\nparticle-bath atomistic motion. The derivation is done within the framework of\nnonaffine linear response theory. The new formula may lead to a valid\nalternative to the Green-Kubo approach to describe the viscosity of condensed\nmatter systems from molecular simulations without having to fit long-time\ntails. Furthermore, it provides a direct link between the viscosity, the\nvibrational density of states of the system, and the zero-frequency limit of\nthe memory kernel.",
        "positive": "Statistics of Bubble Rearrangements in a Slowly Sheared Two-dimensional\n  Foam: Many physical systems exhibit plastic flow when subjected to slow steady\nshear. A unified picture of plastic flow is still lacking; however, there is an\nemerging theoretical understanding of such flows based on irreversible motions\nof the constituent ``particles'' of the material. Depending on the specific\nsystem, various irreversible events have been studied, such as T1 events in\nfoam and shear transformation zones (STZ's) in amorphous solids. This paper\npresents an experimental study of the T1 events in a model, two-dimensional\nfoam: bubble rafts. In particular, I report on the connection between the\ndistribution of T1 events and the behavior of the average stress and average\nvelocity profiles during both the initial elastic response of the bubble raft\nand the subsequent plastic flow at sufficiently high strains."
    },
    {
        "anchor": "Avalanches and Dynamical Correlations in supercooled liquids: We identify the pattern of microscopic dynamical relaxation for a two\ndimensional glass forming liquid. On short timescales, bursts of irreversible\nparticle motion, called cage jumps, aggregate into clusters. On larger time\nscales, clusters aggregate both spatially and temporally into avalanches. This\npropagation of mobility, or dynamic facilitation, takes place along the soft\nregions of the systems, which have been identified by computing\nisoconfigurational Debye-Waller maps. Our results characterize the way in which\ndynamical heterogeneity evolves in moderately supercooled liquids and reveal\nthat it is astonishingly similar to the one found for dense glassy granular\nmedia.",
        "positive": "Undulation Amplitude of a Fluid Membrane in a Near-Critical Binary Fluid\n  Mixture Calculated beyond the Gaussian Model Supposing Weak Preferential\n  Attraction: We calculate the mean square amplitude of the shape fluctuation -- an\nequal-time correlation -- of an almost planar fluid membrane immersed in a\nnear-critical binary fluid mixture. One fluid component is usually\npreferentially attracted by the membrane, and becomes more concentrated around\nit because of the near criticality. This generates osmotic pressure, which\ninfluences the amplitude. The amplitude is also affected by the reversible\ndynamics of the mixture, which moves with the membrane. By assuming the\nGaussian free-energy functional and weak preferential attraction, the author\npreviously showed that a new term is added to the restoring force of the\nmembrane and tends to suppress the amplitude. Not assuming both of them, but\nstill focusing on modes with wavelength longer than the correlation length, we\nhere calculate the amplitude of a tensionless membrane. First, within the\nGaussian model, we solve the governing equations to show that, for long\nwavelength, the additional term becomes predominant, although decreased\nhydrodynamic effects make its numerical factor approximately half that of the\nprevious result. The change in the term turns out not to be monotonic with the\nwavelength, which is mainly caused by the change in the induced mass. Second,\nassuming the critical composition far from the membrane, we calculate the\namplitude beyond the regime of the Gaussian model. The result coincides roughly\nwith the corresponding result in the Gaussian model if the correlation length\nis interpreted as one close to the membrane."
    },
    {
        "anchor": "Reply to the comment from Ikeda, Berthier, and Sollich: This is a reply to the recent comment from Ikeda, Berthier, and Sollich\n(arXiv:1602.04796) on \"Constant stress and pressure rheology of colloidal\nsuspensions\", Phys. Rev. Lett. 115, 158301 (2015).",
        "positive": "Simulations of Blood Flow in Plain Cylindrical and Constricted Vessels\n  with Single Cell Resolution: Understanding the physics of blood is challenging due to its nature as a\nsuspension of soft particles and the fact that typical problems involve\ndifferent scales. This is valid also for numerical investigations. In fact,\nmany computational studies either neglect the existence of discrete cells or\nresolve relatively few cells very accurately. The authors recently developed a\nsimple and highly efficient yet still particulate model with the aim to bridge\nthe gap between currently applied methods. The present work focuses on its\napplicability to confined flows in vessels of diameters up to 100 micrometres.\nFor hematocrit values below 30 percent, a dependence of the apparent viscosity\non the vessel diameter in agreement with experimental literature data is found."
    },
    {
        "anchor": "Long-Range Electron Transfer and Electronic Transport Through\n  Macromolecules: A theory of electrical transport through molecular wires is used to estimate\nthe electronic factor in the intramolecular electron transfer (ET) in\nporphyrin-nitrobenzene supermolecules, and to analyze its structure. The chosen\nmolecules have complex donor and acceptor configurations, and relatively simple\nstructure of the bridge, which enables us to concentrate our studies on the\ndonor/acceptor coupling to the bridge. We present analytical and numerical\nresults concerning the effect of donor/acceptor coupling to the bridge on the\nET process in molecules with complex donor/acceptor subsystems.\n  PACS 05.60.Gg, 36.20.-r",
        "positive": "Dynamics and interactions of particles in a thermophoretic trap: We investigate dynamics and interactions of particles levitated and trapped\nby the thermophoretic force in a vacuum cell. Our analysis is based on footage\ntaken by orthogonal cameras that are able to capture the three dimensional\ntrajectories of the particles. In contrast to spherical particles, which remain\nstationary at the center of the cell, here we report new qualitative features\nof the motion of particles with non-spherical geometry. Singly levitated\nparticles exhibit steady spinning around their body axis and rotation around\nthe symmetry axis of the cell. When two levitated particles approach each\nother, repulsive or attractive interactions between the particles are observed.\nOur levitation system offers a wonderful platform to study interaction between\nparticles in a microgravity environment."
    },
    {
        "anchor": "Effect of different geometrically nonlinear strain measures on the\n  static nonlinear response of isotropic and composite shells with constant\n  curvature: The structural analysis of ultra-lightweight flexible shells and membranes\nmay require the adoption of complex nonlinear strain-displacement relations.\nThese may be approximated and simplified in some circumstances, e.g., in the\ncase of moderately large displacements and rotations, in some others may be\nnot. In this paper, the effectiveness of various geometrically nonlinear strain\napproximations such as the von Karman strains is investigated by making use of\nrefined shell formulations based on the Carrera Unified Formulation (CUF).\nFurthermore, geometrical nonlinear equations are written in a total Lagrangian\nframework and solved with an opportune Newton-Raphson method. Test cases\ninclude the study of shells subjected to pinched loadings, combined flexure and\ncompression, and post-buckling including snap-through problems. It is\ndemonstrated that full geometrically nonlinear analysis accounting for full\nGreen-Lagrange strains shall be performed whenever displacements are higher\nthan the order of magnitude of the thickness and if compressive loads are\napplied.",
        "positive": "Binding Energies in Benzene Dimers: Nonlocal Density Functional\n  Calculations: The interaction energy and minimum energy structure for different geometries\nof the benzene dimer has been calculated using the recently developed nonlocal\ncorrelation energy functional for calculating dispersion interactions. The\ncomparison of this straightforward and relatively quick density functional\nbased method with recent calculations can elucidate how the former, quicker\nmethod might be exploited in larger more complicated biological, organic,\naromatic, and even infinite systems such as molecules physisorbed on surfaces,\nand van der Waals crystals."
    },
    {
        "anchor": "A Study on the Wetting Properties of Broccoli Leaf Surfaces and their\n  Time Dependent Self-Healing After Mechanical Damage: Plants are protected from the elements by a complex hierarchical epicuticular\nwax layer which has inspired the creation of super-hydrophobic and\nself-cleaning surfaces. Although many studies have been conducted on different\nplant wax systems to determine the mechanisms of water repulsion hardly any\nhave studied the recovery of the epicuticular wax layer. In the current study\nthe wetting properties and crystallographic nature of the wax surface of\nBrassica oleracea var. Italica (broccoli) has been studied, as well as the\ntime-dependent recovery of the surface after mechanical damage. It was found\nthat the surface of the broccoli leaves is not only super-repulsive and\nself-cleaning in regards to water but also in regards to glycerol and formamide\nboth of which have considerably lower surface tension values. Furthermore, it\nwas shown that the surface properties do indeed recover after damage and that\nthis recovery is multi-steped and strongly dependent on the recovery of the\nroughness of the surface",
        "positive": "Hydrodynamic and contact contributions to shear thickening in colloidal\n  suspensions: Shear thickening is a widespread phenomenon in suspension flow that, despite\nsustained study, is still the subject of much debate. The longstanding view\nthat shear thickening is due to hydrodynamic clusters has been challenged by\nrecent theory and simulations suggesting that contact forces dominate, not only\nin discontinuous, but also in continuous shear thickening. Here, we settle this\ndispute using shear reversal experiments on micron-sized silica and latex\ncolloidal particles to measure directly the hydrodynamic and contact force\ncontributions to shear thickening. We find that contact forces dominate even\ncontinuous shear thickening. Computer simulations show that these forces most\nlikely arise from frictional interactions."
    },
    {
        "anchor": "Emergence of synchronised rotations in dense active matter with disorder: We consider the rich variety of collective motion patterns emerging when\naligning active particles move in the presence of randomly distributed\nobstacles - representing quenched noise in two dimensions. In order to get\ninsight into the involved complex flows and the transitions between them we use\na simple model allowing the observation and analysis of behaviors that are less\nstraightforwardly accessible by experiments or analytic calculations. We find a\nseries of symmetry breaking states in spite of the applied disorder being\nisotropic. In particular, as the level of perturbations is increased, the\nsystem of self-propelled particles changes its collective motion patterns from\ni) directed flow ii) through a mixed state of locally directed or locally\nrotating flow to iii) a novel, globally synchronized rotating state thereby the\nsystem violating overall chiral symmetry. Finally, this phase crosses over to a\nstate in which iv) clusters of locally synchronized rotations are observed. The\nway of change from polar flow to overall synchronization can be interpreted as\nindicating a non-reciprocal phase transition. Our simulations suggest that when\nboth present, quenched rather than shot noise dominates the behaviors.",
        "positive": "Effect of the granular material on the maximum holding force of a\n  granular gripper: A granular gripper is a device used to hold objects by taking advantage of\nthe phenomenon of Reynold's dilatancy. A membrane containing a granular sample\nis allowed to deform around the object to be held and then vacuum is used to\njam the granular material inside the membrane. This allows to hold the object\nagainst external forces since deformation of the granular material is prevented\nby not allowing the system to increase its volume. The maximum holding force\nsupported by the gripper depends on a number of variables. In this work, we\nshow that in the regime of frictional holding (where the gripper does not\ninterlock with the object), the maximum holding force does not depend on the\ngranular material used to fill the membrane. Results for a variety of granular\nmaterials can be collapsed into a single curve if maximum holding force is\nplotted against the penetration depth achieved. The results suggest that the\nmost important feature in selecting a particular granular material is its\ndeformability to ensure an easy flow during the initial phase of the gripping\nprocess."
    },
    {
        "anchor": "Thermal Conductivity Minimum: A New Water Anomaly: We report a new anomaly of water, a minimum in the thermal conductivity in\nthe supercooled region. Our findings are consistent with the presence of a\nliquid-liquid phase transition in water",
        "positive": "Advanced eco-friendly formulations of guar biopolymer-based textile\n  conditioners: Fabric conditioners are household products used to impart softness and\nfragrance to tex-tiles. They are colloidal dispersions of cationic double chain\nsurfactants that self-assemble in vesicles. These surfactants are primarily\nderived from palm oil chemical modification. Reducing the content of these\nsurfactants allows to obtain products with lower environmental impact. Such a\nreduction, without adverse effects on the characteristics of the softener and\nits performance, can be achieved by adding hydrophilic biopolymers. Here, we\nreview the role of guar biopolymers modified with cationic or hydroxyl-propyl\ngroups on the physicochemical properties of the formulation. Electronic and\noptical microscopy, dynamic light scattering, X-ray scattering and rheology of\nvesicles dispersion in absence and in presence of guar biopolymers are\nanalyzed. Finally, the deposition of the new formulation on cotton fabrics is\nexamined through scanning electron microscopy and a new protocol based on\nfluorescent microscopy. With this methodology it is possible to quantify the\ndeposition of surfactants on cotton fibers. The results show that the approach\nfollowed here can facilitate the design of sustainable home-care products."
    },
    {
        "anchor": "Mesoscopic wave physics in fish shoals: Ultrasound scattered by a dense shoal of fish undergoes mesoscopic\ninterference, as is typical of low-temperature electrical transport in metals\nor light scattering in colloidal suspensions. Through large-scale measurements\nin open sea, we show a set of striking deviations from classical wave diffusion\nmaking fish shoals good candidates to study mesoscopic wave phenomena. The very\ngood agreement with theories enlightens the role of fish structure on such a\nstrong scattering regime that features slow energy transport and brings\nacoustic waves close to the Anderson localization transition.",
        "positive": "Coarse-Grained Kinetic Computations for Rare Events: Application to\n  Micelle Formation: We discuss a coarse-grained approach to the computation of rare events in the\ncontext of grand canonical Monte Carlo (GCMC) simulations of self-assembly of\nsurfactant molecules into micelles. The basic assumption is that the {\\it\ncomputational} system dynamics can be decomposed into two parts -- fast (noise)\nand slow (reaction coordinates) dynamics, so that the system can be described\nby an effective, coarse grained Fokker-Planck (FP) equation. While such an\nassumption may be valid in many circumstances, an explicit form of FP equation\nis not always available. In our computations we bypass the analytic derivation\nof such an effective FP equation. The effective free energy gradient and the\nstate-dependent magnitude of the random noise, which are necessary to formulate\nthe effective Fokker-Planck equation, are obtained from ensembles of short\nbursts of microscopic simulations {\\it with judiciously chosen initial\nconditions}. The reaction coordinate in our micelle formation problem is taken\nto be the size of a cluster of surfactant molecules. We test the validity of\nthe effective FP description in this system and reconstruct a coarse-grained\nfree energy surface in good agreement with full-scale GCMC simulations. We also\nshow that, for very small clusters, the cluster size seizes to be a good\nreaction coordinate for a one-dimensional effective description. We discuss\npossible ways to improve the current model and to take higher-dimensional\ncoarse-grained dynamics into account."
    },
    {
        "anchor": "Effect of the alkyl chain length of the alcohols on the nematic\n  uniaxial-to-biaxial phase transitions in the potassium\n  laurate/alcohol/K2SO4/water lyotropic mixture: Lyotropic liquid crystalline quaternary mixtures of potassium laurate (KL),\npotassium sulphate (K2SO4)/alcohol (n-OH)/water, with the alcohols having\ndifferent number of carbon atoms in the alkyl chain (n), from 1 octanol to\n1-hexadecanol, were investigated by optical techniques (optical microscopy and\nlaser conoscopy). The biaxial nematic phase domain is present in a window of\nvalues of n = nKL \\pm 2, where nKL = 11 is the number of carbon atoms in the\nalkyl chain of KL. The biaxial phase domain got smaller and the\nuniaxial-to-biaxial phase transition temperatures shifted to the relatively\nhigher temperatures on going from 1-nonanol to 1-tridecanol. Moreover, these\nnew mixtures present high values of the birefringences comparing to other\nlyotropic mixtures. This result is expected to be related to the micellar shape\nanisotropy. Our results are interpreted assuming that alcohol molecules tend to\nsegregate in the micelles in a way that depends on the relative value of n with\nrespect to nKL . The larger the value of n, the more alcohol molecules tend to\nbe located in the curved parts of the micelle, favoring the uniaxial nematic\ncalamitic phase with respect to the biaxial and uniaxial discotic nematic\nphases.",
        "positive": "Active rotational dynamics of a self-diffusiophoretic colloidal motor: The dynamics of a spherical chemically-powered synthetic colloidal motor that\noperates by a self-diffusiophoretic mechanism and has a catalytic domain of\narbitrary shape is studied using both continuum theory and particle-based\nsimulations. The motor executes active rotational motion when self-generated\nconcentration gradients and interactions between the chemical species and\ncolloidal motor surface break spherical symmetry. Local variations of chemical\nreaction rates on the motor catalytic surface with catalytic domain sizes and\nshapes provide such broken symmetry conditions. A continuum theoretical\ndescription of the active rotational motion is given, along with the results of\nparticle-based simulations of the active dynamics. From these results a\ndetailed description of the factors responsible for the active rotational\ndynamics can be given. Since active rotational motion often plays a significant\npart in the nature of the collective dynamics of many-motor systems and can be\nused to control motor motion in targeted cargo transport, our results should\nfind applications beyond those considered here."
    },
    {
        "anchor": "Dispersions of ellipsoidal particles in a nematic liquid crystal: Colloidal particles dispersed in a partially ordered medium, such as a liquid\ncrystal (LC) phase, disturb its alignment and are subject to elastic forces.\nThese forces are long-ranged, anisotropic and tunable through temperature or\nexternal fields, making them a valuable asset to control colloidal assembly.\nThe latter is very sensitive to the particle geometry since it alters the\ninteractions between the colloids. We here present a detailed numerical\nanalysis of the energetics of elongated objects, namely prolate ellipsoids,\nimmersed in a nematic host. The results, complemented with qualitative\nexperiments, reveal novel LC configurations with peculiar topological\nproperties around the ellipsoids, depending on their aspect ratio and the\nboundary conditions imposed on the nematic order parameter. The latter also\ndetermine the preferred orientation of ellipsoids in the nematic field, because\nof elastic torques, as well as the morphology of particles aggregates.",
        "positive": "Simple models for granular force networks: A remarkable feature of static granular matter is the distribution of force\nalong intricate networks. Even regular inter-particle contact networks produce\nwildly inhomogeneous force networks where certain \"chains\" of particles carry\nforces far larger than the mean. In this paper, we briefly review past\ntheoretical approaches to understanding the geometry of force networks. We then\ninvestigate the structure of experimentally-obtained granular force networks\nusing a simple algorithm to obtain corresponding graphs. We compare our\nobservations with the results of geometric models, including random bond\npercolation, which show similar spatial distributions without enforcing vector\nforce balance. Our findings suggest that some aspects of the mean geometry of\ngranular force networks may be captured by these simple descriptions."
    },
    {
        "anchor": "Effect of Polymerization on the Boson Peak, from the Liquid to Glassy\n  Phase: Raman scattering measurements are used to follow the modification of the\nvibrational density of states in a reactive epoxy{amine mixture during\nisothermal polymerization. Combining with Brillouin light and inelastic x-ray\nscattering measurements, we analyze the variations of the boson peak and of the\nDebye level while the system passes from the uid to a glassy phase upon\nincreasing the number of covalent bonds among the constituent molecules. We\nfind that the shift and the intensity decrease of the boson peak are fully\nexplained by the modification of the elastic medium throughout the reaction.\nSurprisingly, bond-induced modifications of the structure do not affect the\nrelative excess of states over the Debye level.",
        "positive": "Measuring granular flow through a funnel with a force sensor: This paper presents an apparatus to measure the flow of granular matter\nthrough a funnel with a force sensor. In addition to being easily reproducible,\nour proposed method enhances measurement accuracy from the popular method that\nuses a stopwatch. We notice, however, that our proposed setup induces an\nunwelcome force that confounds force sensor readings. This issue is discussed,\nand its significance on measurement accuracy is evaluated through theoretical\nand experimental work."
    },
    {
        "anchor": "The self-assembly of DNA Holliday junctions studied with a minimal model: In this paper, we explore the feasibility of using coarse-grained models to\nsimulate the self-assembly of DNA nanostructures. We introduce a simple model\nof DNA where each nucleotide is represented by two interaction sites\ncorresponding to the phosphate-sugar backbone and the base. Using this model,\nwe are able to simulate the self-assembly of both DNA duplexes and Holliday\njunctions from single-stranded DNA. We find that assembly is most successful in\nthe temperature window below the melting temperatures of the target structure\nand above the melting temperature of misbonded aggregates. Furthermore, in the\ncase of the Holliday junction, we show how a hierarchical assembly mechanism\nreduces the possibility of becoming trapped in misbonded configurations. The\nmodel is also able to reproduce the relative melting temperatures of different\nstructures accurately, and allows strand displacement to occur.",
        "positive": "Splay and polar order in a system of hard pear-like molecules:\n  confrontation of Monte Carlo numerical simulations with density functional\n  theory calculations: Recent experimental discoveries of novel nematic types with polar order,\nincluding ferroelectric nematic and splay nematic have brought the resurgence\nof the interest in polar and modulated phases. One of the most important\nfactors that is widely believed to be crucial for the formation of the new\nphases is the pear-like shape of the mesogenic molecules. Such molecules were\ntreated using second-virial density functional theory in [De Gregorio, P\n\\textit{et al.}, \\textit{Soft Matter}, 2016, \\textbf{12(23)}, 5188-5198], where\nthe authors showed that the $K_{11}$ splay elastic constant can become negative\ndue to solely entropic reasons leading to long-range splay and polar\ncorrelations. To verify whether the predictions are correct, we performed Monte\nCarlo simulations of the same hard-core molecules used in the DFT study. As our\nresults suggest, no polar or modulated liquid crystalline phases emerge; polar\nand splay correlations are at most short-range or completely absent. On the\nother hand, a polar ferroelectric splay crystal was observed."
    },
    {
        "anchor": "Early stages of aggregation in fluid mixtures of dimers and spheres: a\n  theoretical and simulation study: We use Monte Carlo simulation and the Reference Interaction Site Model (RISM)\ntheory of molecular fluids to investigate a simple model of colloidal mixture\nconsisting of dimers, made up of two tangent hard monomers of different size,\nand hard spheres. In addition to steric repulsion, the two species interact via\na square-well attraction only between small monomers and spheres. Recently, we\nhave characterized the low-temperature regime of this mixture by Monte Carlo,\nreporting on the spontaneous formation of a wide spectrum of supramolecular\naggregates [Prestipino et al, J. Phys. Chem. B, 2019, 123, 9272]. Here we focus\non a regime of temperatures where, on cooling, the appearance of local\ninhomogeneties first, and the early stages of aggregation thereafter, are\nobserved. In particular, we find signatures of aggregation in the onset of a\nlow-wavevector peak in the structure factors of the mixture, as computed by\nboth theory and simulation. Then, we link the structural information to the\nmicroscopic arrangement through a detailed cluster analysis of Monte Carlo\nconfigurations. In this regard, we devise a novel method to compute the maximum\ndistance for which two spheres can be regarded as bonded together, a crucial\nissue in the proper identification of fluid aggregates. The RISM theory\nprovides relatively accurate structural and thermodynamic predictions in\ncomparison with Monte Carlo, but with slightly degrading performances as the\nfluid progresses inside the locally inhomogeneous phase. Our study certifies\nthe efficacy of the RISM approach as a useful complement to numerical\nsimulation for a reasoned analysis of aggregation properties in colloidal\nmixtures.",
        "positive": "Spin Probe ESR Signature of Freezing in Water: Is it Global or Local?: First systematic spin probe ESR study of water freezing has been conducted\nusing TEMPOL and TEMPO as the probes. The spin probe signature of the water\nfreezing has been described in terms of the collapse of narrow triplet spectrum\ninto a single broad line. This spin probe signature of freezing has been\nobserved at an anomalously low temperature when a milimoler solution of TEMPOL\nis slowly cooled from room temperature. A systematic observation has revealed a\nspin probe concentration dependence of these freezing and respective melting\npoints. These results can be explained in terms of localization of spin probe\nand liquid water, most probably in the interstices of ice grains, in an ice\nmatrix. The lowering of spin probe freezing point, along with the secondary\nevidences, like spin probe concentration dependence of peak-to-peak width in\nfrozen limit signal, indicates a possible size dependence of these\nlocalizations/entrapments with spin probe concentration. A weak concentration\ndependence of spin probe assisted freezing and melting points, which has been\nobserved for TEMPO in comparison to TEMPOL, indicates different natures of\ninteractions with water of these two probes. This view is also supported by the\nrelaxation behavior of the two probes."
    },
    {
        "anchor": "Average Evolution and Size-Topology Relations for Coarsening 2d Dry\n  Foams: Two-dimensional dry foams coarsen according to the von Neumann law as $dA/dt\n\\propto (n-6)$ where $n$ is the number of sides of a bubble with area $A$. Such\nfoams reach a self-similar scaling state where area and side-number\ndistributions are stationary. Combining self-similarity with the von Neumann\nlaw, we derive time derivatives of moments of the bubble area distribution and\na relation connecting area moments with averages of the side-number\ndistribution that are weighted by powers of bubble area. To test these\npredictions, we collect and analyze high precision image data for a large\nnumber of bubbles squashed between parallel acrylic plates and allowed to\ncoarsen into the self-similar scaling state. We find good agreement for moments\nranging from two to twenty.",
        "positive": "Exactly isochoric deformations of soft solids: Many materials of contemporary interest, such as gels, biological tissues and\nelastomers, are easily deformed but essentially incompressible. Traditional\nlinear theory of elasticity implements incompressibility only to first order\nand thus permits some volume changes, which become problematically large even\nat very small strains. Using a mixed coordinate transformation originally due\nto Gauss, we enforce the constraint of isochoric deformations exactly to\ndevelop a linear theory with perfect volume conservation that remains valid\nuntil strains become geometrically large. We demonstrate the utility of this\napproach by calculating the response of an infinite soft isochoric solid to a\npoint force that leads to a nonlinear generalization of the Kelvin solution.\nOur approach naturally generalizes to a range of problems involving\ndeformations of soft solids and interfaces in 2 dimensional and axisymmetric\ngeometries, which we exemplify by determining the solution to a distributed\nload that mimics muscular contraction within the bulk of a soft solid."
    },
    {
        "anchor": "Restructuring of colloidal aggregates in shear flow: Coupling\n  interparticle contact models with Stokesian dynamics: A method to couple interparticle contact models with Stokesian dynamics (SD)\nis introduced to simulate colloidal aggregates under flow conditions. The\ncontact model mimics both the elastic and plastic behavior of the cohesive\nconnections between particles within clusters. Owing to this, clusters can\nmaintain their structures under low stress while restructuring or even breakage\nmay occur under sufficiently high stress conditions. SD is an efficient method\nto deal with the long-ranged and many-body nature of hydrodynamic interactions\nfor low Reynolds number flows. By using such a coupled model, the restructuring\nof colloidal aggregates under stepwise increasing shear flows was studied.\nIrreversible compaction occurs due to the increase of hydrodynamic stress on\nclusters. Results show that the greater part of the fractal clusters are\ncompacted to rod-shaped packed structures, while the others show isotropic\ncompaction.",
        "positive": "Velocity Fluctuations in a Slowly Sheared Bubble Raft: A surprising feature of flow in slowly sheared model foam (bubble raft) is a\nmeasured discontinuity in the rate of strain as a function of position such\nthat part of the system is ``flowing'' and the rest is undergoing ``elastic''\ndeformations [J. Lauridsen, G. Chanan, and M. Dennin, Phys. Rev. Lett. v. 93,\n018303 (2004)]. Detailed measurements of the distribution of nonlinear bubble\nrearrangements have been reported in connection with this discontinuity. In\nthis paper, measurements of the fluctuations in velocity under the same\nconditions are reported. The fluctuations are characterized by the second and\nthird moments of the velocity distribution. A surprising feature is the\nqualitative behavior of these moments as a function of position in the system,\nespecially across the discontinuity in rate of strain. In addition, the\nmeasured dependence of the second moment of the velocity fluctuations on rate\nof strain is compared with predictions of simulations of the bubble model and\nreasonable agreement is found."
    },
    {
        "anchor": "Modular approach to microswimming: The field of active matter in general and microswimming in particular has\nexperienced a rapid and ongoing expansion over the last decade. A particular\ninteresting aspect is provided by artificial autonomous microswimmers\nconstructed from individual active and inactive functional components into\nself-propelling complexes. Such modular microswimmers may exhibit directed\nmotion not seen for each individual component. In this review, we focus on the\nestablishment and recent developments in the modular approach to microswimming.\nWe introduce the bound and dynamic prototypes, show mechanisms and types of\nmodular swimming and discuss approaches to control the direction and speed of\nmodular microswimmers. We conclude by highlighting some challenges faced by\nresearchers as well as promising directions for future research in the realm of\nmodular swimming.",
        "positive": "Diverse Spreading Behavior of Binary Polymer Nanodroplets: Molecular dynamics simulations are used to study the spreading of binary\npolymer nanodroplets in a cylindrical geometry. The polymers, described by the\nbead-spring model, spread on a flat surface with a surface-coupled Langevin\nthermostat to mimic the effects of a corrugated surface. Each droplet consists\nof chains of length 10 or 100 monomers with ~350,000 monomers total. The\nqualitative features of the spreading dynamics are presented for differences in\nchain length, surface interaction strength, and composition. When the\ncomponents of the droplet differ only in surface interaction strength, the more\nstrongly wetting component forms a monolayer film on the surface even when both\nmaterials are above or below the wetting transition. In the case where the only\ndifference is the polymer chain length, the monolayer film beneath the droplet\nis composed of an equal amount of short chain and long chain monomers even when\none component (the shorter chain length) is above the wetting transition and\nthe other is not. The fraction of short and long chains in the precursor foot\ndepends on whether or not both the short and long chains are in the wetting\nregime. Diluting the concentration of the strongly wetting component in a\nmixture with a weakly wetting component decreases the rate of diffusion of the\nwetting material to the surface and limits the spreading rate of the precursor\nfoot, but the bulk spreading rate is not affected until the more strongly\nwetting component is removed completely."
    },
    {
        "anchor": "Smoluchowski equations for linker-mediated irreversible aggregation: In order to study linker-mediated aggregation of colloidal particles with\nlimited valence, we combine kinetic Monte Carlo simulations and an approximate\ntheory based on the Smoluchowski equations. We found that aggregation depends\nstrongly on two parameters, the ratio of the number of linkers and particles\nand the ratio of their diffusion coefficients. These control parameters are\nabsent in single-species aggregation and provide a much greater variety and\ncontrol of the resulting structures. We show that aggregation is non-trivial\nwhen two time scales of aggregation are present. Our aggregation dynamics\ntheory is in qualitative and quantitative agreement with kinetic Monte Carlo\nsimulations. Our results show how the optimal aggregation may be tuned through\nthe ratio of the linkers and particles and that of the diffusion coefficients.",
        "positive": "The Role of Ionization in Thermal Transport of Solid Polyelectrolytes: Amorphous polymers are known as thermal insulators, increasing their thermal\nconductivities have not been guided by fully understood physics. In this work,\nwe use molecular dynamics simulations to study the thermal transport mechanism\nof solid polyelectrolytes, poly(acrylic acid) (PAA) and its ionized forms. The\nthermal conductivity of PAA increases monotonically with the ionization\nstrength. Although stronger ionization induces larger Coulombic interactions,\nthe Coulombic interaction does not directly contribute to the thermal\nconductivity enhancement. Instead, it enhances thermal transport through the\nLennard-Jones (LJ) interaction. The strong Coulombic force between the\ncounterion and the ionized carboxylic group shifts the LJ force to the stronger\nLJ repulsive regime, which is mainly responsible for the improved thermal\nconductivity. Applying a high pressure can further reduce the inter-atomic\ndistance and trigger the thermal transport through the LJ interaction. A\nthermal conductivity of 1.09 W/m.K can be achieved at 11.2 GPa in an ionized\nPAA."
    },
    {
        "anchor": "Dynamical noise and avalanches in quasi-static plastic flow of amorphous\n  solids: We build a mean-field model of plasticity of amorphous solids, based on the\ndynamics of an ensemble shear transformation zones, interacting via intrinsic\ndynamical noise generated by the zone flips themselves. We compare the\nquasi-static, steady-state properties for two types of noise spectrum: (G)\nGaussian; (E) broad distribution derived from quadrupolar elastic interactions.\nWe find that the plastic flow proceeds via avalanches whose scaling properties\nwith system size are highly sensitive to noise tails. Comparison with available\ndata suggests that non-affine strain fields might be of paramount importance in\nthe small systems accessible to molecular simulations.",
        "positive": "Magnetostriction in elastomers with mixtures of magnetically hard and\n  soft microparticles: effects of non-linear magnetization and matrix rigidity: In this contribution a magnetoactive elastomer (MAE) of mixed content, i.e.,\na polymer matrix filled with a mixture of magnetically soft and magnetically\nhard spherical particles, is considered. The object we focus at is an\nelementary unit of this composite, for which we take a set consisting of a\npermanent spherical micromagnet surrounded by an elastomer layer filled with\nmagnetically soft microparticles. We present a comparative treatment of this\nunit from two essentially different viewpoints. The first one is a\ncoarse-grained molecular dynamics simulation model, which presents the\ncomposite as a bead-spring assembly and is able to deliver information of all\nthe microstructural changes of the assembly. The second approach is entirely\nbased on the continuum magnetomechanical description of the system, whose\ndirect yield is the macroscopic field-induced response of the MAE to external\nfield, as this model ignores all the microstructural details of the\nmagnetization process. We find that, differing in certain details, both\nframeworks are coherent in predicting that a unit comprising magnetically soft\nand hard particles may display a non-trivial re-entrant\n(prolate/oblate/prolate) axial deformation under variation of the applied field\nstrength.\n  The flexibility of the proposed combination of the two complementary\nframeworks enables us to look deeper into the manifestation of the magnetic\nresponse: with respect to the magnetically soft particles, we compare the\nlinear regime of magnetization to that with saturation, which we describe by\nthe Fr\\\"{o}hlich-Kennelly approximation; with respect to the polymer matrix, we\nanalyze the dependence of the re-rentrant deformation on its rigidity."
    },
    {
        "anchor": "Self-organization in systems of self-propelled particles: We investigate a discrete model consisting of self-propelled particles that\nobey simple interaction rules. We show that this model can self-organize and\nexhibit coherent localized solutions in one- and in two-dimensions.In\none-dimension, the self-organized solution is a localized flock of finite\nextent in which the density abruptly drops to zero at the edges.In\ntwo-dimensions, we focus on the vortex solution in which the particles rotate\naround a common center and show that this solution can be obtained from random\ninitial conditions, even in the absence of a confining boundary. Furthermore,\nwe develop a continuum version of our discrete model and demonstrate that the\nagreement between the discrete and the continuum model is excellent.",
        "positive": "How moving cracks in brittle solids choose their path: While we fundamentally understand the dynamics of 'simple' cracks propagating\nin brittle solids within perfect (homogeneous) materials, we do not understand\nhow paths of moving cracks are determined. We experimentally study strongly\nperturbed cracks that propagate between 10-95\\% of their limiting velocity\nwithin a brittle material. These cracks are deflected by either interaction\nwith sparsely implanted defects or via an intrinsic oscillatory instability in\ndefect-free media. Dense, high-speed measurements of the strain fields\nsurrounding the crack tips reveal that crack paths are governed by the\ndirection of maximal strain energy density. This fundamentally important result\nmay be utilized to either direct or guide running cracks."
    },
    {
        "anchor": "Interfacial fluid rheology of soft particles: In situ interfacial rheology and numerical simulations are used to\ninvestigate microgel monolayers in a wide range of packing fractions,\n$\\zeta_{2D}$. The heterogeneous particle compressibility determines two flow\nregimes characterized by distinct master curves. To mimic the microgel\narchitecture and reproduce experiments, an interaction potential combining a\nsoft shoulder with the Hertzian model is introduced. In contrast to bulk\nconditions, the elastic moduli vary non-monotonically with $\\zeta_{2D}$ at the\ninterface, confirming long-sought predictions of reentrant behavior for\nHertzian-like systems.",
        "positive": "The stochastic flow rule: A multi-scale model for granular plasticity: In spite of many attempts to model dense granular flow, there is still no\ngeneral theory capable of describing different types of flows, such as\ngravity-driven drainage in silos and wall-driven shear flows in Couette cells.\nHere, we summarize our recent proposal of the Stochastic Flow Rule (SFR), which\nis able to describe these cases in good agreement with experiments, and we\nfocus on testing the theory in more detail against brute-force simulations with\nthe discrete-element method (DEM). The SFR is a general rate-independent\nconstitutive law for plastic flow, based on diffusing spots of fluidization. In\nthe case of quasi-2D granular materials, we assume limit-state stresses from\nMohr-Coulomb plasticity and postulate that spots undergo biased random walks\nalong slip-lines, driven by local stress imbalances. We compare analytical\npredictions of the SFR against DEM simulations for silos and Couette cells,\ncarrying out several parametric studies in the latter case, and find good\nagreement."
    },
    {
        "anchor": "Geometrical properties of mechanically annealed systems near the jamming\n  transition: Geometrical properties of two-dimensional mixtures near the jamming\ntransition point are numerically investigated using harmonic particles under\nmechanical training. The configurations generated by the quasi-static\ncompression and oscillatory shear deformations exhibit anomalous suppression of\nthe density fluctuations, known as hyperuniformity, below and above the jamming\ntransition. For the jammed system trained by compression above the transition\npoint, the hyperuniformity exponent increases. For the system below the\ntransition point under oscillatory shear, the hyperuniformity exponent also\nincreases until the shear amplitude reaches the threshold value. The threshold\nvalue matches with the transition point from the point-reversible phase where\nthe particles experience no collision to the loop-reversible phase where the\nparticles' displacements are non-affine during a shear-cycle before coming back\nto an original position. The results demonstrated in this paper are explained\nin terms of neither of universal criticality of the jamming transition nor the\nnonequilibrium phase transitions.",
        "positive": "Landau kinetic equation for dry aligning active models: The Landau equation is a kinetic equation based on the weak coupling\napproximation of the interaction between the particles. In the framework of dry\nactive matter this new kinetic equation relies on the weak coupling\napproximation of both the alignment strength and the magnitude of the angular\nnoise, instead of the hypothesis of diluteness. Therefore, it is a kinetic\nequation bridging between the Boltzmann [3], and the Smoluchowski [2]\napproximations, and allowing analytical descriptions at moderate densities. The\nform of the equation presents non-linear and density dependent diffusions and\nadvections fully derived by the microscopic equations of motions. Finally,\nimplementing the BGL procedure [25], the parameters of the Toner-Tu equations\nare derived showing the appearance of linearly stable homogeneous ordered\nsolutions and mimicking the results obtained from the Boltzmann approach."
    },
    {
        "anchor": "Quantitative Tube Model for Semiflexible Polymer Solutions: We develop a analytical and quantitative theory of the tube model concept for\nentangled networks of semiflexible polymers. The absolute value of the tube\ndiameter L_perp is derived as a function of the polymers' persistence length\nl_p and mesh size xi of the network. To leading order we find L_\\perp = 0.32\nxi^{6/5} l_p^{-1/5}, which is consistent with known asymptotic scaling laws.\nAdditionally, our theory provides corrections to scaling that account for\nfinite polymer length effects and are dominated by the mesh size to polymer\nlength ratio. We support our analytical studies by extensive computer\nsimulations. These allow to verify assumptions essential to our theoretical\ndescription and provide an excellent agreement with the analytically calculated\ntube diameter. Furthermore, we present simulation data for the distribution\nfunction of tube widths in the network.",
        "positive": "Dilatancy in dense suspensions of model hard-sphere-like colloids under\n  shear and extensional flow: Dense suspensions of model hard-sphere-like colloids, with different particle\nsizes, are examined experimentally in the glass state, under shear and\nextensional rheology. Under steady shear flow we detect Discontinuous Shear\nThickening (DST) above a critical shear rate. Start-up shear experiments show\nstress overshoots in the vicinity of the onset of DST related with a change in\nmicroscopic morphology, as the sample shows dilatancy effects. The analysis of\nthe normal stress together with direct sample observation by high speed camera,\nindicates the appearance of positive N1 and dilation behavior at the shear\nthickening onset. Dilatancy effects are detected also under extensional flow.\nThe latter was studied through capillary breakup and filament stretching\nexperimental setups, where liquid-like response is seen for strain rate lower\nthan a critical strain rate and solid like-behavior for higher strain rates.\nMonitoring the filament thinning processes under different conditions (volume\nfractions and strain rates) we have created a state diagram where all responses\nof a hard-sphere suspension (Newtonian, shear thinning, shear thickening,\ndilatant) are shown. We finally compare the shear thickening response of these\nhard-sphere-like suspensions and glasses in shear with that in extensional\nflow."
    },
    {
        "anchor": "How does the first water shell fold proteins so fast ?: First shells of hydration and bulk solvent plays a crucial role in the\nfolding of proteins. Here, the role of water in the dynamics of proteins has\nbeen investigated using a theoretical protein-solvent model and a statistical\nphysics approach. We formulate a hydration model where the hydrogen bonds\nbetween water molecules pertaining to the first shell of the protein\nconformation may be either mainly formed or broken. At thermal equilibrium,\nhydrogen bonds are formed at low temperature and are broken at high\ntemperature. To explore the solvent effect, we follow the folding of a large\nsampling of protein chains, using a master-equation evolution. The dynamics\nshows a clear mechanism. Above the glass-transition temperature, a large ratio\nof chains fold very rapidly into the native structure irrespective of the\ntemperature, following pathways of high transition rates through structures\nsurrounded by the solvent with broken hydrogen bonds. Although these states\nhave an infinitesimal probability, they act as strong dynamical attractors and\nfast folding proceeds along these routes rather than pathways with small\ntransition rates between configurations of much higher equilibrium\nprobabilities. At a given low temperature, a broad jump in the folding times is\nobserved. Below this glass temperature, the pathways where hydrogen bonds are\nmainly formed become those of highest rates although with conformational\nchanges of huge relaxation times. The present results reveal that folding obeys\na double-funnel mechanism.",
        "positive": "Generic elasticity of thermal, under-constrained systems: Athermal (i.e. zero-temperature) under-constrained systems are typically\nfloppy, but they can be rigidified by the application of external strain, which\nis theoretically well understood. Here and in the companion paper, we extend\nthis theory to finite temperatures for a very broad class of under-constrained\nsystems. In the vicinity of the athermal transition point, we derive from first\nprinciples expressions for elastic properties such as isotropic tension $t$ and\nshear modulus $G$ on temperature $T$, isotropic strain $\\varepsilon$, and shear\nstrain $\\gamma$, which we confirm numerically. These expressions contain only\nthree phenomenological parameters, entropic rigidity $\\kappa_S$, energetic\nrigidity $\\kappa_E$, and a parameter $b_\\varepsilon$ describing the interaction\nbetween isotropic and shear strain. Our results imply that in under-constrained\nsystems, entropic and energetic rigidity interact like two springs in series.\nThis also allows for a simple explanation of the previously numerically\nobserved scaling relation $t\\sim G\\sim T^{1/2}$ at $\\varepsilon=\\gamma=0$. Our\nwork unifies the physics of systems as diverse as polymer fibers & networks,\nmembranes, and vertex models for biological tissues."
    },
    {
        "anchor": "Phase behavior and far-from-equilibrium gelation of charged attractive\n  colloids: In this Rapid Communication we demonstrate the applicability of an augmented\nGibbs ensemble Monte Carlo approach for the phase behavior determination of\nmodel colloidal systems with short-ranged depletion attraction and long-ranged\nrepulsion. This technique allows for a quantitative determination of the phase\nboundaries and ground states in such systems. We demonstrate that gelation may\noccur in systems of this type as the result of arrested microphase separation,\neven when the equilibrium state of the system is characterized by compact\nmicrophase structures.",
        "positive": "Log it: How to fit an active Brownian particle's mean squared\n  displacement with improved parameter estimation: The active Brownian particle (ABP) model is widely used to describe the\ndynamics of active matter systems, such as Janus microswimmers. In particular,\nthe analytical expression for an ABP's mean-squared-displacement (MSD) is\nuseful as it provides a means to describe the essential physics of a\nself-propelled, spherical Brownian particle. However, the truncated or\n'short-time' form of the MSD equation is typically fitted, which can lead to\nsignificant problems in parameter estimation. Furthermore, heteroscedasticity\nand the often statistically dependent observations of an ABP's MSD lead to a\nsituation where standard ordinary least squares (OLS) regression will obtain\nbiased estimates and unreliable confidence intervals. Here, we propose to\nrevert to always fitting the full expression of an ABP's MSD at short\ntimescales, using bootstrapping to construct confidence intervals of the fitted\nparameters. Additionally, after comparison between different fitting\nstrategies, we propose to extract the physical parameters of an ABP using its\nmean logarithmic squared displacement (MLSD). These steps improve the\nestimation of an ABP's physical properties, and provide more reliable\nconfidence intervals, which are critical in the context of a growing interest\nin the interactions of microswimmers with confining boundaries and the\ninfluence on their motion."
    },
    {
        "anchor": "Common mechanism of thermodynamic and mechanical origin for ageing and\n  crystallisation of glasses: The glassy state is known to undergo slow structural relaxation, where the\nsystem progressively explores lower free-energy minima which are either\namorphous (ageing) or crystalline (devitrification). Recently, there is growing\ninterest in the unusual intermittent collective displacements of a large number\nof particles known as \"avalanches\". However, their structural origin and\ndynamics are yet to be fully addressed. Here, we study hard-sphere glasses\nwhich either crystallise or age depending on the degree of size polydispersity,\nand show that a small number of particles are thermodynamically driven to\nrearrange in regions of low density and bond orientational order. This causes a\ntransient loss of mechanical equilibrium which facilitates a large cascade of\nmotion. Combined with previously identified phenomenology, we have a complete\nkinetic pathway for structural change which is common to both ageing and\ncrystallisation. Furthermore, this suggests that transient force balance is\nwhat distinguishes glasses from supercooled liquids.",
        "positive": "Effective forces between colloids at interfaces induced by capillary\n  wave-like fluctuations: We calculate the effective force mediated by thermally excited capillary\nwaves between spherical or disklike colloids trapped at a fluid interface. This\nCasimir type interaction is shown to depend sensitively on the boundary\nconditions imposed at the three-phase contact line. For large distances between\nthe colloids an unexpected cancellation of attractive and repulsive\ncontributions is observed leading to a fluctuation force which decays\nalgebraically very rapidly. For small separations the resulting force is rather\nstrong and it may play an important role in two-dimensional colloid aggregation\nif direct van der Waals forces are weak."
    },
    {
        "anchor": "Flow curves of colloidal dispersions close to the glass transition:\n  Asymptotic scaling laws in a schematic model of mode coupling theory: The flow curves, viz. the curves of stationary stress under steady shearing,\nare obtained close to the glass transition in dense colloidal dispersions using\nasymptotic expansions in a schematic model of mode coupling theory. The shear\nthinning of the viscosity in fluid states and the yielding of glassy states is\ndiscussed. At the transition between fluid and shear-molten glass, simple and\ngeneralized Herschel-Bulkley laws are derived with power law exponents that can\nbe computed for different particle interactions from the equilibrium structure\nfactor.",
        "positive": "Surface nanobubbles: Seeing is believing: The existence of surface nanobubbles has been previously suggested using\nvarious experimental techniques, including attenuated total reflection\nspectroscopy, quartz crystal microbalance, neutron reflectometry, and x-ray\nreflectivity, but all of these techniques provide a sole number to quantify the\nexistence of gas over (usually) hundreds of square microns. Thus `nanobubbles'\nare indistinguishable from a `uniform gassy layer' between surface and liquid.\nAtomic force microscopy, on the other hand, does show the existence of surface\nnanobubbles, but the highly intrusive nature of the technique means that a\nuniform gassy layer could break down into nanobubbles \\textit{due to} the\nmotion of the microscope's probe. Here we demonstrate \\textit{optical}\nvisualisation of surface nanobubbles, thus validating their individual\nexistence non-intrusively."
    },
    {
        "anchor": "Characterizing Structure Through Shape Matching and Applications to Self\n  Assembly: Structural quantities such as order parameters and correlation functions are\noften employed to gain insight into the physical behavior and properties of\ncondensed matter systems. While standard quantities for characterizing\nstructure exist, often they are insufficient for treating problems in the\nemerging field of nano and microscale self-assembly, where the structures\nencountered may be complex and unusual. The computer science field of \"shape\nmatching\" offers a robust solution to this problem by defining diverse methods\nfor quantifying the similarity between arbitrarily complex shapes. Most order\nparameters and correlation functions used in condensed matter apply a specific\nmeasure of structural similarity within the context of a broader scheme. By\nsubstituting shape matching quantities for traditional quantities, we retain\nthe essence of the broader scheme, but extend its applicability to more complex\nstructures. Here we review some standard shape matching techniques and discuss\nhow they might be used to create highly flexible structural metrics for diverse\nsystems such as self-assembled matter. We provide three proof-of-concept\nexample problems applying shape matching methods to identifying local and\nglobal structures, and tracking structural transitions in complex assembled\nsystems. The shape matching methods reviewed here are applicable to a wide\nrange of condensed matter systems, both simulated and experimental, provided\nparticle positions are known or can be accurately imaged.",
        "positive": "Jamming of frictional spheres and random loose packing: The role of friction coefficient, $\\mu$, on the jamming properties of\ndisordered, particle packings is studied using computer simulations.\nCompressed, soft-sphere packings are brought towards the jamming transition -\nthe point where a packing loses mechanical stability - by decreasing the\npacking fraction. The values of the packing fraction at the jamming transition,\n$\\phi^{\\mu}_{c}$, gradually decrease from the random close packing point for\nzero friction, to a value coincident with random loose packing as the friction\ncoefficient is increased over several orders of magnitude. This is accompanied\nby a decrease in the coordination number at the jamming transition,\n$z^{\\mu}_{c}$, which varies from approximately six to four with increasing\nfriction. Universal power law scaling is observed in the pressure and\ncoordination number as a function of distance from the generalised,\nfriction-dependent jamming point. Various power laws are also reported between\nthe $\\phi^{\\mu}_{\\rm c}$, $z^{\\mu}_{\\rm c}$, and $\\mu$. Dependence on\npreparation history of the packings is also investigated."
    },
    {
        "anchor": "Selection of defect structures in twist-grain-boundary-A phase of chiral\n  liquid crystals: We study the structure of the twist grain boundary in chiral smectic liquid\ncrystals using the Landau-de Gennes model. By considering spatial variation of\nthe smectic order, we distinguish the Melted-Grain-Boundary-A (MGBA) structure\nwith cholesteric-like domains and the Twist-Grain-Boundary-A (TGBA) structure\nconsisting of screw dislocations. The MGBA structure becomes stable near the\ntransition to the cholesteric phase. On approaching the transition, the\ncholesteric-like domain grows outside the grain boundary. Also, the dislocation\nspacings of the TGBA structure agree better with experimental results than\nprevious theories.",
        "positive": "Triangular lattice models for pattern formation by core-shell particles\n  with different shell thicknesses: Triangular lattice models for pattern formation by hard-core soft-shell\nparticles at interfaces are introduced and studied in order to determine the\neffect of the shell thickness and structure. In model I, we consider particles\nwith hard-cores covered by shells of cross-linked polymeric chains. In model\nII, such inner shell is covered by a much softer outer shell. In both models,\nthe hard cores can occupy sites of the triangular lattice, and nearest-neighbor\nrepulsion following from overlapping shells is assumed. The capillary force is\nrepresented by the second- or the fifth neighbor attraction in model I or II,\nrespectively. Ground states with fixed chemical potential $\\mu$ or with fixed\nfraction of occupied sites c are thoroughly studied. For T > 0, the $\\mu(c)$\nisotherms, compressibility and specific heat are calculated by Monte Carlo\nsimulations. In model II, 6 ordered periodic patterns occur in addition to 4\nphases found in model I. These additional phases, however, are stable only at\nthe phase coexistence lines, i.e. in regions of zero measure at the $(\\mu,T)$\ndiagram which otherwise looks like the diagram of model I. In the canonical\nensemble, these 6 phases and interfaces between them appear in model II for\nlarge intervals of c, and the number of possible patterns is much larger than\nin model I. We calculated surface tensions for different interfaces and found\nthat the favorable orientation of the interface corresponds to its smoothest\nshape in both models."
    },
    {
        "anchor": "Temperature as an external field for colloid-polymer mixtures :\n  \"quenching\" by heating and \"melting\" by cooling: We investigate the response to temperature of a well-known colloid-polymer\nmixture. At room temperature, the critical value of the second virial\ncoefficient of the effective interaction for the Asakura-Oosawa model predicts\nthe onset of gelation with remarkable accuracy. Upon cooling the system, the\neffective attractions between colloids induced by polymer depletion are\nreduced, because the polymer radius of gyration is decreases as the\ntheta-temperature is approached. Paradoxically, this raises the effective\ntemperature, leading to \"melting\" of colloidal gels. We find the Asakura-Oosawa\nmodel of effective colloid interactions with a simple description of the\npolymer temperature response provides a quantitative description of the\nfluid-gel transition. Further we present evidence for enhancement of\ncrystallisation rates near the metastable critical point.",
        "positive": "Modelling the non-steady peeling of viscoelastic tapes: We present a model to study the non-steady V-shaped peeling of a viscoelastic\nthin tape adhering to a rigid flat substrate. Geometry evolution and\nviscoelastic creep in the tape are the main features involved in the process,\nwhich allows to derive specific governing equations in the framework of energy\nbalance. Finally, these are numerically integrated following an iterative\nscheme to calculate the process evolution assuming different controlling\nconditions (peeling front velocity, peeling force, tape tip velocity). Results\nshow that the peeling behavior is strongly affected by viscoelasticity.\nSpecifically, for a given applied force, the peeling can either be prevented,\nstart and stop after some while, or endlessly propagate, depending on the\noriginal undeformed tape geometry. Viscoelasticity also entails that the\ninterface toughness strongly increases when the tape tip is fast pulled, which\nagrees to recent experimental observations on tougher adhesion of natural\nsystems under impact loads, such as see waves and wind gusts."
    },
    {
        "anchor": "Polar state memory in active fluids: Spontaneous emergence of correlated states such as flocks and vortices are\nprime examples of remarkable collective dynamics and self-organization observed\nin active matter. The formation of globally correlated polar states in\ngeometrically confined systems proceeds through the emergence of a macroscopic\nsteadily rotating vortex that spontaneously selects a clockwise or\ncounterclockwise global chiral state. Here, we reveal that a global vortex\nformed by colloidal rollers exhibits state memory. The information remains\nstored even when the energy injection is ceased and the activity is terminated.\nWe show that a subsequent formation of the collective states upon re-energizing\nthe system is not random. We combine experiments and simulations to elucidate\nhow a combination of hydrodynamic and electrostatic interactions leads to\nhidden asymmetries in the local particle positional order encoding the chiral\nstate of the system. The stored information can be accessed and exploited to\nsystematically command subsequent polar states of active liquid through\ntemporal control of the activity. With the chirality of the emergent collective\nstates controlled on-demand, active liquids offer new possibilities for flow\nmanipulation, transport, and mixing at the microscale.",
        "positive": "Pattern formation of phase-separated lipid domains in bilayer membranes: Giant unilamellar vesicles (GUVs) composed of as few as three lipid species\ncan phase separate into small-scale lipid domains with stripes and dots\npatterns. These patterns have been experimentally characterized in terms of how\ntheir size and morphology depend on temperature, membrane composition, and\nsurface tension, which revealed inconsistencies with existing theoretical\nmodels. Here, we demonstrate that the experiments can be explained with a\ntheory that considers both the elastic deformation of the membrane and the\nphase separation of lipids, which are coupled by a preferred bilayer curvature.\nWe combine analytical and numerical approaches to elucidate how characteristic\npattern size and morphology emerge from these interactions. The results agree\nwith existing experiments and offer testable predictions such as non-monotonic\ndependence of the domain size on osmotic pressure and pattern hysteresis upon\ncycling external stimuli. These predictions motivate new directions for\nunderstanding the spatial patterning and organization mechanisms of biological\nmembranes."
    },
    {
        "anchor": "Role of plasticity in the universal scaling of shear thickening dense\n  suspensions: Increase in viscosity under increasing shear stress, known as shear\nthickening (ST), is one of the most striking properties of dense particulate\nsuspensions. Under appropriate conditions, they exhibit discontinuous shear\nthickening (DST), where the viscosity increases dramatically and can also\ntransform into a solid-like state due to shear induced jamming (SJ). The\nmicroscopic mechanism giving rise to such interesting phenomena is still a\ntopic of intense research. A phenomenological model proposed by Wyart and Cates\nshows that the proliferation of stress-activated interparticle frictional\ncontacts can give rise to such striking flow properties. Building on this\nmodel, a recent work proposes and verifies a universal scaling relation for ST\nsystems where two different power-law regimes with a well-defined crossover\npoint is obtained. Nonetheless, the difference in the nature of the flow in\nthese two scaling regimes remains unexplored. Here, using rheology in\nconjugation with high-speed optical imaging, we study the flow and local\ndeformations in various ST systems. We observe that with increasing applied\nstress, the smooth flow changes into a spatio-temporally varying flow across\nthe scaling-crossover. We show that such fluctuating flow is associated with\nintermittent dilatancy, shear band plasticity and fracture induced by system\nspanning frictional contacts.",
        "positive": "A unified field theory of topological defects and non-linear local\n  excitations: Topological defects and smooth excitations determine the properties of\nsystems showing collective order. We introduce a generic non-singular field\ntheory that comprehensively describes defects and excitations in systems with\n$O(n)$ broken rotational symmetry. Within this formalism, we explore fast\nevents, such as defect nucleation/annihilation and dynamical phase transitions\nwhere the interplay between topological defects and non-linear excitations is\nparticularly important. To highlight its versatility, we apply this formalism\nin the context of Bose-Einstein condensates, active nematics, and crystal\nlattices."
    },
    {
        "anchor": "Free energy and extension of a semiflexible polymer in cylindrical\n  confining geometries: We consider a long, semiflexible polymer, with persistence length $P$ and\ncontour length $L$, fluctuating in a narrow cylindrical channel of diameter\n$D$. In the regime $D\\ll P\\ll L$ the free energy of confinement $\\Delta F$ and\nthe length of the channel $R_\\parallel$ occupied by the polymer are given by\nOdijk's relations $\\Delta F/R_\\parallel=A_\\circ k_BTP^{-1/3}D^{-2/3}$ and\n$R_\\parallel=L[1-\\alpha_\\circ(D/P)^{2/3}]$, where $A_\\circ$ and $\\alpha_\\circ$\nare dimensionless amplitudes. Using a simulation algorithm inspired by PERM\n(Pruned Enriched Rosenbluth Method), which yields results for very long\npolymers, we determine $A_\\circ$ and $\\alpha_\\circ$ and the analogous\namplitudes for a channel with a rectangular cross section. For a semiflexible\npolymer confined to the surface of a cylinder, the corresponding amplitudes are\nderived with an exact analytic approach. The results are relevant for\ninterpreting experiments on biopolymers in microchannels or microfluidic\ndevices.",
        "positive": "Shear hardening in frictionless amorphous solids near the jamming\n  transition: The jamming transition, generally manifested by a rapid increase of rigidity\nunder compression (i.e., compression hardening), is ubiquitous in amorphous\nmaterials. Here we study shear hardening in deeply annealed frictionless\npackings generated by numerical simulations, reporting critical scalings absent\nin compression hardening. We demonstrate that hardening is a natural\nconsequence of shear-induced memory destruction. Based on an elasticity theory,\nwe reveal two independent microscopic origins of shear hardening: (i) the\nincrease of the interaction bond number and (ii) the emergence of anisotropy\nand long-range correlations in the orientations of bonds, the latter highlights\nthe essential difference between compression and shear hardening. Through the\nestablishment of physical laws specific to anisotropy, our work completes the\ncriticality and universality of jamming transition, and the elasticity theory\nof amorphous solids."
    },
    {
        "anchor": "Collective and non-collective molecular dynamics in a ferroelectric\n  nematic liquid crystal studied by broadband dielectric spectroscopy: A great deal of effort has been recently devoted to the study of dielectric\nrelaxation processes in ferroelectric nematic liquid crystals, yet their\ninterpretation remains unclear. In this work, we present the results of\nbroadband dielectric spectroscopy experiments of a prototypical ferroelectric\nnematogen in the frequency range 10 Hz-110 MHz at different electrode\nseparations and under the application of DC bias fields. The results evidence a\ncomplex behavior in all phases due to the magnitude of polar correlations in\nthese systems. The observed modes have been assigned to different relaxation\nmechanisms based on existing theoretical frameworks.",
        "positive": "Bi-axial shear of confined colloidal suspensions: the structure and\n  rheology of the vorticity-aligned string phase: Using a novel bi-axial confocal rheoscope, we investigate the structure and\nrheology of sheared colloidal suspensions under confinement. Consistent with\nprevious work [X. Cheng \\textit{et al., Proc. Natl. Acad. Sci. U. S. A.}, 2011,\n109, 63], we observe a vorticity-aligned string phase in moderate concentrated\ncolloidal suspensions under uniaxial shear. Using bi-axial shear protocols, we\ndirectly manipulate the orientation and morphology of the string structures.\nSimultaneously, we measure the suspension rheology along both the flow and\nvorticity directions with a bi-axial force measurement device. Our results\ndemonstrate that despite the highly anisotropic microstructure, the suspension\nviscosity remains isotropic and constant over the shear rates explored. These\nresults suggest that hydrodynamic contributions dominate the suspension\nresponse. In addition they highlight the capabilities of bi-axial confocal\nrheoscopes for elucidating the relationship between microstructure and rheology\nin complex fluids."
    },
    {
        "anchor": "A Machine Learning Approach to Robustly Determine Director Fields and\n  Analyze Defects in Active Nematics: Active nematics are dense systems of rodlike particles that consume energy to\ndrive motion at the level of the individual particles. They exist in natural\nsystems like biological tissues and artificial materials such as suspensions of\nself-propelled colloidal particles or synthetic microswimmers. Active nematics\nhave attracted significant attention in recent years due to their spectacular\nnonequilibrium collective spatiotemporal dynamics, which may enable\napplications in fields such as robotics, drug delivery, and materials science.\nThe director field, which measures the direction and degree of alignment of the\nlocal nematic orientation, is a crucial characteristic of active nematic and is\nessential for studying topological defects. However, determining the director\nfield is a significant challenge in many experimental systems. Although\ndirector fields can be derived from images of active nematics using traditional\nimaging processing methods, the accuracy of such methods are highly sensitive\nto the settings of the algorithms. These settings must be tuned from\nimage-to-image due to experimental noise, intrinsic noise of the imaging\ntechnology, and perturbations caused by changes in experimental conditions.\nThis sensitivity currently limits automatic analysis of active nematics. To\naddress this, we developed a machine learning model for extracting reliable\ndirector fields from raw experimental images, which enables accurate analysis\nof topological defects. Application of the algorithm to experimental data\ndemonstrates that the approach is robust and highly generalizable to\nexperimental settings that are different from those in the training data. It\ncould be a promising tool for investigating active nematics and may be\ngeneralized to other active matter systems.",
        "positive": "Nematic-Isotropic Spinodal Decomposition Kinetics of Rod-like Viruses: We investigate spinodal decomposition kinetics of an initially nematic\ndispersion of rod-like viruses (fd virus). Quench experiments are performed\nfrom a flow-stabilized homogeneous nematic state at high shear rate into the\ntwo-phase isotropic-nematic coexistence region at zero shear rate. We present\nexperimental evidence that spinodal decomposition is driven by orientational\ndiffusion, in accordance with a very recent theory."
    },
    {
        "anchor": "Correlation between flexibility of chain-like polyelectrolyte and\n  thermodynamic properties of its solution: Structural and thermodynamic properties of the model solution containing\ncharged oligomers and the equivalent number of counterions were studied by\nmeans of the canonical Monte Carlo simulation technique. The oligomers are\nrepresented as (flexible) freely jointed chains or as a linear (rigid) array of\ncharged hard spheres. In accordance with the primitive model of electrolyte\nsolutions, the counterions are modeled as charged hard spheres and the solvent\nas dielectric continuum. Significant differences in the pair distribution\nfunctions, obtained for the rigid (rod-like) and flexible model are found but\nthe differences in thermodynamic properties, such as, enthalpy of dilution and\nexcess chemical potential, are less significant. The results are discussed in\nlight of the experimental data an aqueous polyelectrolyte solutions. The\nsimulations suggest that deviations from the fully extended (rod-like)\nconformation yield slightly stronger binding of counterions. On the other hand,\nthe flexibility of polyions, even when coupled with the ion-size effects,\ncannot be blamed for qualitative differences between the theoretical results\nand experimental data for enthalpy of dilution.",
        "positive": "Interplay of inertia and deformability on rheological properties of a\n  suspension of capsules: The interplay of inertia and deformability has a substantial impact on the\ntransport of soft particles suspended in a fluid. However, to date a thorough\nunderstanding of these systems is still missing and only a limited number of\nexperimental and theoretical studies is available. We combine the\nfinite-element, immersed-boundary and lattice-Boltzmann methods to simulate\nthree-dimensional suspensions of soft particles subjected to planar Poiseuille\nflow at finite Reynolds numbers. Our findings confirm that the particle\ndeformation and inclination increase when inertia is present. We observe that\nthe Segr\\'e-Silberberg effect is suppressed with respect to the particle\ndeformability. Depending on the deformability and strength of inertial effects,\ninward or outward lateral migration of the particles takes place. In\nparticular, for increasing Reynolds numbers and strongly deformable particles,\na hitherto unreported distinct flow focusing effect emerges which is\naccompanied by a non-monotonic behaviour of the apparent suspension viscosity\nand thickness of the particle-free layer close to the channel walls. This\neffect can be explained by the behaviour of a single particle and the change of\nthe particle collision mechanism when both deformability and inertia effects\nare relevant."
    },
    {
        "anchor": "A polyurethane-urea elastomer at low to extreme strain rates: A finite strain nonlinear constitutive model is presented to study the\nextreme mechanical behavior of a polyurethane-urea well suited for many\nengineering applications. The micromechanically- and thermodynamically based\nconstitutive model captures salient features in resilience and dissipation in\nthe material at low to high strain rate. The extreme deformation features are\nfurther elucidated by laser-induced micro-particle impact tests for the\nmaterial, where an ultrafast strain rate ($>10^6$ s$^{-1}$) incurs. Numerical\nsimulations for the strongly inhomogeneous deformation events are in good\nagreement with the experimental data, supporting the predictive capabilities of\nthe constitutive model for the extreme deformation features of the PUU material\nover at least 9 orders of magnitude in strain rates ($10^{-3}$ to $10^{6}$\ns$^{-1}$).",
        "positive": "Realization of the Najafi-Golestanian microswimmer: A paradigmatic microswimmer is the three-linked-spheres model, which follows\na minimalist approach for propulsion by shape shifting. As such, it has been\nthe subject of numerous analytical and numerical studies. In this Rapid\nCommunication, an experimental three-linked-spheres swimmer is created by\nself-assembling ferromagnetic particles at an air-water interface. It is\npowered by a uniform oscillating magnetic field. A model, using two harmonic\noscillators, reproduces the experimental findings. Because the model remains\ngeneral, the same approach could be used to design a variety of efficient\nmicroswimmers."
    },
    {
        "anchor": "On the nature of Thermal Diffusion in binary Lennard-Jones liquids: The aim of this study is to understand deeper the thermal diffusion transport\nprocess (Ludwig-Soret effect) at the microscopic level. For that purpose, the\nrecently developed reverse nonequilibrium molecular dynamics method was used to\ncalculate Soret coefficients of various systems in a systematic fashion. We\nstudied binary Lennard-Jones (LJ) fluids near the triple point (of one of the\ncomponents) in which we separately changed the ratio of one of the LJ\nparameters mass, atomic diameter and interaction strength while keeping all\nother parameters fixed and identical. We observed that the magnitude of the\nSoret coefficient depends on all three ratios. Concerning its sign we found\nthat heavier species, smaller species and species with higher interaction\nstrengths tend to accumulate in the cold region whereas the other ones\n(lighter, bigger or weaker bound) migrate to the hot region of our simulation\ncell. Additionally, the superposition of the influence of the various\nparameters was investigated as well as more realistic mixtures. We found that\nin the experimentally relevant parameter range the contributions are nearly\nadditive and that the mass ratio often is the dominating factor.",
        "positive": "Mechanical properties of simple computer glasses: Recent advances in computational glass physics enable the study of computer\nglasses featuring a very wide range of mechanical and kinetic stabilities. The\ncurrent literature, however, lacks a comprehensive data set against which\ndifferent computer glass models can be quantitatively compared on the same\nfooting. Here we present a broad study of the mechanical properties of several\npopular computer glass forming models. We examine how various dimensionless\nnumbers that characterize the glasses' elasticity and elasto-plasticity vary\nunder different conditions --- in each model and across models --- with the aim\nof disentangling the model-parameter-, external-parameter- and\npreparation-protocol-dependencies of these observables. We expect our data set\nto be used as an interpretive tool in future computational studies of\nelasticity and elasto-plasticity of glassy solids."
    },
    {
        "anchor": "Geometric and Dynamic Properties of Entangled Polymer Chains in Athermal\n  Solvents: A Coarse-Grained Molecular Dynamics Study: We used a coarse-grained model to study the geometric and dynamic properties\nof flexible entangled polymer chains dissolved in explicit athermal solvents.\nOur simulations successfully reproduced the geometrical properties including\nthe scaling relationships between mean-square end-to-end distance $<R_{ee}^2>$,\nchain entanglement lengths $N_{e}$ and concentration $\\Phi$. Specifically, we\nfind that $<R_{ee}^2>\\sim N*\\Phi^{-1/4}$,$N_{e} = 30.01\\Phi^{-5/4}+31.23$.\nDynamically, our model confirmed the ratio of the dynamic critical entanglement\n$N_{c}$ and the geometric entanglement length $N_{e}$ is constant, with\n$N_{c}/N_{e} = 5\\sim 6$. To account for the local swelling effect for chains\nconfined in athermal solvents, we treated the chains using the concept of blobs\nwhere each blob occupies a volume $\\Omega_{b}$, with length $g$. Direct MD\nsimulations and scaling analysis showed that $g \\sim \\Phi^{-25/36}$,\n$\\Omega_{b}\\sim\\Phi^{-5/4}$. Using these together with the concentration\ndependent packing length $p \\sim \\Phi^{-5/12}$, we obtained a modified the\nLin-Noolandi ansatz for concentrated flexible polymer chains in athermal\nsolvents: $G \\sim \\frac{\\Phi}{\\left(N_{e} / g\\right) \\Omega_{b}} \\sim\n\\Phi^{-2.28}$. We demonstrate this modified ansatz agrees well with our\ncoarse-grained numerical simulations.",
        "positive": "A Deep Potential model for liquid-vapor equilibrium and cavitation rates\n  of water: Computational studies of liquid water and its phase transition into vapor\nhave traditionally been performed using classical water models. Here we utilize\nthe Deep Potential methodology -- a machine learning approach -- to study this\nubiquitous phase transition, starting from the phase diagram in the\nliquid-vapor coexistence regime. The machine learning model is trained on ab\ninitio energies and forces based on the SCAN density functional which has been\npreviously shown to reproduce solid phases and other properties of water. Here,\nwe compute the surface tension, saturation pressure and enthalpy of\nvaporization for a range of temperatures spanning from 300 to 600 K, and\nevaluate the Deep Potential model performance against experimental results and\nthe semi-empirical TIP4P/2005 classical model. Moreover, by employing the\nseeding technique, we evaluate the free energy barrier and nucleation rate at\nnegative pressures for the isotherm of 296.4 K. We find that the nucleation\nrates obtained from the Deep Potential model deviate from those computed for\nthe TIP4P/2005 water model, due to an underestimation in the surface tension\nfrom the Deep Potential model. From analysis of the seeding simulations, we\nalso evaluate the Tolman length for the Deep Potential water model, which is\n(0.091 $\\pm$ 0.008) nm at 296.4 K. Lastly, we identify that water molecules\ndisplay a preferential orientation in the liquid-vapor interface, in which H\natoms tend to point towards the vapor phase to maximize the enthalpic gain of\ninterfacial molecules. We find that this behaviour is more pronounced for\nplanar interfaces than for the curved interfaces in bubbles. This work\nrepresents the first application of Deep Potential models to the study of\nliquid-vapor coexistence and water cavitation."
    },
    {
        "anchor": "Strain-stiffening elastomers fail from the edge: The accurate measurement of fracture resistance in elastomers is essential\nfor predicting the mechanical limits of soft devices. Usually, this is achieved\nby performing tearing or peeling experiments on thin-sheet samples. Here, we\nshow that these tests can be surprisingly thickness-dependent, with thicker\nsamples being significantly stronger than thinner ones. Even for a simple\ngeometry, direct imaging of the fracture surface shows that the fracture\nprocess actually involves three distinct cracks: an inner crack, and two edge\ncracks. Ultimately, samples fail when two edge cracks meet at the sample's\nmid-plane. The opening angle of edge crack, $2 \\theta$, determines how far the\nsample has to be stretched before the edge cracks meet. Conveniently, $\\theta$\nis a material property that can be inferred from the elastomer's non-linear\nelastic response. To yield thickness-independent fracture-test results, sample\nthickness should be much smaller than the smallest lateral sample dimension\ndivided by $\\tan \\theta$. Our results have direct implications for\ncharacterizing, understanding, and modelling fracture in soft elastomers.",
        "positive": "Slow regions percolate near glass transition: A nano-second scale in situ probe reveals that a bulk linear polymer\nundergoes a sharp phase transition as a function of the degree of conversion,\nas it nears the glass transition. The scaling behaviour is in the same\nuniversality class as percolation. The exponents \\gamma and \\beta are found to\nbe 1.7 \\pm .1 and 0.41\\pm 0.01 in agreement with the best percolation results\nin three dimensions."
    },
    {
        "anchor": "Comment on ``Adsorption of Polyelectrolyte onto a Colloid of Opposite\n  Charge'': In a recent Letter, Gurovitch and Sens studied the adsorption of a weakly\ncharged polyelectrolyte chain onto an oppositely charged colloidal particle. By\nusing a variational technique they found that the colloidal particle can adsorb\na polymer of higher charge than its own, and thus be ``overcharged.'' I argue\nthat the observed overcharging by a factor of 16/5 is indeed an artifact of the\napproximations involved in the study. Moreover, I show that the existence of\novercharging depends crucially on the choice of the trial wave function,\ncontrary to their claim.",
        "positive": "Density Functional Theory for Hard Particles in N Dimensions: Recently it has been shown that the heuristic Rosenfeld functional derives\nfrom the virial expansion for particles which overlap in one center. Here, we\ngeneralize this approach to any number of intersections. Starting from the\nvirial expansion in Ree-Hoover diagrams, it is shown in the first part that\neach intersection pattern defines exactly one infinite class of diagrams.\nDetermining their automorphism groups, we sum over all its elements and derive\na generic functional. The second part proves that this functional factorizes\ninto a convolute of integral kernels for each intersection center. We derive\nthis kernel for N dimensional particles in the N dimensional, flat Euclidean\nspace. The third part focuses on three dimensions and determines the\nfunctionals for up to four intersection centers, comparing the leading order to\nRosenfeld's result. We close by proving a generalized form of the Blaschke,\nSantalo, Chern equation of integral geometry."
    },
    {
        "anchor": "Role of spatial heterogeneity on the collective dynamics of cilia\n  beating in a minimal 1D model: Cilia are elastic hairlike protuberances of the cell membrane found in\nvarious unicellular organisms and in several tissues of most living organisms.\nIn some tissues such as the airway tissues of the lung, the coordinated beating\nof cilia induce a fluid flow of crucial importance as it allows the continuous\ncleaning of our bronchia, known as mucociliary clearance. While most of the\nmodels addressing the question of collective dynamics and metachronal wave\nconsider homogeneous carpets of cilia, experimental observations rather show\nthat cilia clusters are heterogeneously distributed over the tissue surface.\nThe purpose of this paper is to investigate the role of spatial heterogeneity\non the coherent beating of cilia using a very simple one dimensional model for\ncilia known as the rower model. We systematically study systems consisting of a\nfew rowers to hundreds of rowers and we investigate the conditions for the\nemergence of collective beating. When considering a small number of rowers, a\nphase drift occurs, hence a bifurcation in beating frequency is observed as the\ndistance between rowers clusters is changed. In the case of many rowers, a\ndistribution of frequencies is observed. We found in particular the pattern of\nthe patchy structure that shows the best robustness in collective beating\nbehavior, as the density of cilia is varied over a wide range.",
        "positive": "Spatial resolution of spin waves in an ultra-cold gas: We present the first spatially resolved images of spin waves in a gas. The\ncomplete longitudinal and transverse spin field as a function of time and space\nis reconstructed. Frequencies and damping rates for a standing-wave mode are\nextracted and compared with theory."
    },
    {
        "anchor": "Permeation Instabilities in Active, Polar Gels: We present a theory of active, permeating, polar gels, based on a two-fluid\nmodel. An active relative force between the gel components creates a\nsteady-state current. We analyze its stability, while considering two polar\ncoupling terms to the relative current: a permeation-deformation term, which\ndescribes network deformation by the solvent flow, and a permeation-alignment\nterm, which describes the alignment of the polarization field by the network\ndeformation and flow. Novel instability mechanisms emerge at finite wave\nvectors, suggesting the formation of periodic domains and mesophases. Our\nresults can be used to determine the physical conditions required for various\ntypes of multicellular migration across tissues.",
        "positive": "Polyelectrolytes in Solution - Recent Computer Simulations: We present a short overview over recent MD simulations of systems of fully\nflexible polyelectrolyte chains with explicitly treated counter ions using the\nfull Coulomb potential. The main emphasis is given on the conformational\nproperties of the polymers, with a short discussion on counter ion\ncondensation."
    },
    {
        "anchor": "A route to explain water anomalies from results on an aqueous solution\n  of salt: In this paper we investigate the possibility to detect the hypothesized\nliquid-liquid critical point of water in supercooled aqueous solutions of\nsalts. Molecular dynamics computer simulations are conducted on bulk TIP4P\nwater and on an aqueous solution of sodium chloride in TIP4P water, with\nconcentration c = 0.67 mol/kg. The liquid-liquid critical point is found both\nin the bulk and in the solution. Its position in the thermodynamic plane shifts\nto higher temperature and lower pressure for the solution. Comparison with\navailable experimental data allowed us to produce the phase diagrams of both\nbulk water and the aqueous solution as measurable in experiments. Given the\nposition of the liquid-liquid critical point in the solution as obtained from\nour simulations, the experimental determination of the hypothesized\nliquid-liquid critical point of water in aqueous solutions of salts appears\npossible.",
        "positive": "Probability densities of a forced probe particle in glass: results from\n  mode coupling theory and simulations of active microrheology: We investigate the displacements of a probe particle inside a glass, when a\nstrong external force is applied to the probe (active nonlinear microrheology).\nCalculations within mode coupling theory are presented for glasses of hard\nspheres and compared to Langevin and Brownian dynamics simulations. Under not\ntoo strong forces where the probe remains trapped, the probe density\ndistribution becomes anisotropic. It is shifted towards the direction of the\nforce, develops an enhanced tail in that direction (signalled by a positive\nskewness), and exhibits different variances along and perpendicular to the\nforce direction. A simple model of an harmonically trapped probe rationalizes\nthe low force limit, with strong strain softening setting in at forces of the\norder of a few thermal energies per particle radius."
    },
    {
        "anchor": "Effects of interparticle friction on the response of 3D cyclically\n  compressed granular material: We numerically study the effect of inter-particle friction coefficient on the\nresponse to cyclical pure shear of spherical particles in three dimensions. We\nfocus on the rotations and translations of grains and look at the spatial\ndistribution of these displacements as well as their probability distribution\nfunctions. We find that with increasing friction, the shear band becomes\nthinner and more pronounced. At low friction, the amplitude of particle\nrotations is homogeneously distributed in the system and is therefore mostly\nindependent from both the affine and non-affine particle translations. In\ncontrast, at high friction, the rotations are strongly localized in the shear\nzone. This work shows the importance of studying the effects of inter-particle\nfriction on the response of granular materials to cyclic forcing, both for a\nbetter understanding of how rotations correlate to translations in sheared\ngranular systems, and due to the relevance of cyclic forcing for most\nreal-world applications in planetary science and industry.",
        "positive": "Stabilization and Destabilization of Semiflexible Polymers Induced by\n  Spherical Confinement: Spherical confinement can act either stabilizing or destabilizing on the\ncollapsed state of a semi-flexible polymer. General free-energy arguments\nsuggest that the order of the unconstrained collapse transition is the\ndistinguishing factor: First order implies stabilization, second order causes\ndestabilization. We confirm this conjecture by Monte Carlo simulations of a\ncoarse-grained model for semiflexible polymers whose chain stiffness tunes the\ntransition order. The resulting physical picture is potentially relevant for\nother systems under strong confinement such as proteins and DNA."
    },
    {
        "anchor": "Memory-based mediated interactions between rigid particulate inclusions\n  in viscoelastic environments: Many practically relevant materials combine properties of viscous fluids and\nelastic solids to viscoelastic behavior. Our focus is on the induced dynamic\nbehavior of damped finite-sized particulate inclusions in such substances. We\nexplicitly describe history-dependent interactions that emerge between the\nembedded particles. These interactions are mediated by the viscoelastic\nsurroundings. They result from the flows and distortions of the viscoelastic\nmedium when induced by the rigid inclusions. Both, viscoelastic environments of\nterminal fluid-like flow or of completely reversible damped elastic behavior,\nare covered. For illustration and to highlight the role of the formalism in\npotential applications, we briefly address the relevant examples of dragging a\nrigid sphere through a viscoelastic environment together with subsequent\nrelaxation dynamics, the switching dynamics of magnetic fillers in elastic gel\nmatrices, and the swimming behavior of active microswimmers in viscoelastic\nsolutions. The approach provides a basis for more quantitative and extended\ninvestigations of these and related systems in the future.",
        "positive": "Finite-temperature buckling of an extensible rod: Thermal fluctuations can play an important role in the buckling of elastic\nobjects at small scales, such as polymers or nanotubes. In this paper, we study\nthe finite-temperature buckling transition of an extensible rod by analyzing\nfluctuation corrections to the elasticity of the rod. We find that, in both two\nand three dimensions, thermal fluctuations delay the buckling transition, and\nnear the transition, there is a critical regime in which fluctuations are\nprominent and make a contribution to the effective force that is of order\n$\\sqrt{T}$. We verify our theoretical prediction of the phase diagram with\nMonte Carlo simulations."
    },
    {
        "anchor": "Evolution of shock instability in granular gases with viscoelastic\n  collisions: Shocks in granular media have been shown to develop instabilities. We address\nthe role that early stages of shock development have on this type of\ninstability. We look at the evolution of shock waves driven by a piston in a\ndilute system of smooth inelastic disks, using both discrete-particle and\ncontinuum modelling. To mimic a realistic granular gas, viscoelastic collisions\nare approximated with an impact velocity threshold $u^*$ needed for inelastic\ncollisions to occur. We show that behaviour of the shock evolution is dependent\non the ratio of piston velocity to impact velocity threshold $u_p/u^*$, and the\ncoefficient of restitution $\\varepsilon$. For $u_p/u^*=2.0$, we recover shock\nevolution behaving similar to that observed in purely inelastic media. This is\ncharacterized by a short period where the shock front pulls towards the piston\nbefore attaining a developed structure. No pullback is seen for $u_p/u^*=1.0$.\nResults show the onset of instability for these stronger shocks during this\nevolving stage. These results suggest that the early stages of shock evolution\nplay an important role in the shock instability.",
        "positive": "Probing the spatiotemporal dynamics of catalytic Janus particles with\n  single-particle tracking and differential dynamic microscopy: We demonstrate differential dynamic microscopy and particle tracking for the\ncharacterization of the spatiotemporal behavior of active Janus colloids in\nterms of the intermediate scattering function (ISF). We provide an analytical\nsolution for the ISF of the paradigmatic active Brownian particle model and\nfind striking agreement with experimental results from the smallest length\nscales, where translational diffusion and self-propulsion dominate, up to the\nlargest ones, which probe effective diffusion due to rotational Brownian\nmotion. At intermediate length scales, characteristic oscillations resolve the\ncrossover between directed motion to orientational relaxation and allow us to\ndiscriminate active Brownian motion from other reorientation processes, e.g.,\nrun-and-tumble motion. A direct comparison to theoretical predictions reliably\nyields the rotational and translational diffusion coefficients of the\nparticles, the mean and width of their speed distribution, and the temporal\nevolution of these parameters."
    },
    {
        "anchor": "Spreading of Fluids on Solids Under Pressure: Effect of Slip: Spreading of different types of fluid on substrates under an impressed force\nis an interesting problem. Here we study spreading of four fluids, having\ndifferent hydrophilicity and viscosity on two substrates - glass and perspex,\nunder an external force. The area of contact of fluid and solid is\nvideo-photographed and its increase with time is measured. The results for\ndifferent external forces can be scaled onto a common curve. We try to explain\nthe nature of this curve on the basis of existing theoretical treatment where\neither the no-slip condition is used or slip between fluid and substrate is\nintroduced. We find that of the eight cases under study, in five cases\nquantitative agreement is obtained using a slip coefficient.",
        "positive": "Instrinsic oscillations of treadmilling microtubules in a motor bath: We analyse the dynamics of overlapping antiparallel treadmilling microtubules\nin the presence of crosslinking processive motor proteins that counterbalance\nan external force. We show that coupling the force-dependent velocity of motors\nand the kinetics of motor exchange with a bath in the presence of treadmilling\nleads generically to oscillatory behavior. In addition we show that coupling\nthe polymerization kinetics to the external force through the kinetics of the\ncrosslinking motors can stabilize the oscillatory instability into\nfinite-amplitude nonlinear oscillations and may lead to other scenarios,\nincluding bistability."
    },
    {
        "anchor": "Incorporation of excluded volume correlations into Poisson-Boltzmann\n  theory: We investigate the effect of excluded volume interactions on the electrolyte\ndistribution around a charged macroion. First, we introduce a criterion for\ndetermining when hard-core effects should be taken into account beyond standard\nmean field Poisson-Boltzmann (PB) theory. Next, we demonstrate that several\ncommonly proposed local density functional approaches for excluded volume\ninteractions cannot be used for this purpose. Instead, we employ a non-local\nexcess free energy by using a simple constant weight approach. We compare the\nion distribution and osmotic pressure predicted by this theory with Monte Carlo\nsimulations. They agree very well for weakly developed correlations and give\nthe correct layering effect for stronger ones. In all investigated cases our\nsimple weighted density theory yields more realistic results than the standard\nPB approach, whereas all local density theories do not improve on the PB\ndensity profiles but on the contrary, deviate even more from the simulation\nresults.",
        "positive": "Asymmetric Nucleation Processes in Spontaneous Mode Switch of Active\n  Matter: Flocking and vortical are two typical motion modes in active matter. Although\nit is known that the two modes can spontaneously switch between each other in a\nfinite-size system, the switching dynamics remain elusive. In this work, by\ncomputer simulation of a two-dimensional Vicsek-like system with 1000\nparticles, we find from the perspective of classical nucleation theory that the\nforward and backward switching dynamics are asymmetric: from flocking to\nvortical is a one-step nucleation process, while the opposite is a two-step\nnucleation process with the system staying in a metastable state before\nreaching the final flocking state."
    },
    {
        "anchor": "Branching, Capping, and Severing in Dynamic Actin Structures: Branched actin networks at the leading edge of a crawling cell evolve via\nprotein-regulated processes such as polymerization, depolymerization, capping,\nbranching, and severing. A formulation of these processes is presented and\nanalyzed to study steady-state network morphology. In bulk, we identify several\nscaling regimes in severing and branching protein concentrations and find that\nthe coupling between severing and branching is optimally exploited for\nconditions {\\it in vivo}. Near the leading edge, we find qualitative agreement\nwith the {\\it in vivo} morphology.",
        "positive": "Root growth and force chains in a granular soil: Roots provide basic functions to plants such as water/nutrient uptake and\nanchoring in soil. The growth and development of root systems contribute to\ncolonizing the surrounding soil and optimizing the access to resources. It is\nusually admitted that the variability of plant root architecture results from\nthe combination of genetic, physiological and environmental factors, in\nparticular soil mechanical impedance. However this last factor has never been\ninvestigated at the soil grain scale. In this paper, we are interested in the\neffect of the disordered texture of granular soils on the evolution of external\nforces experienced by root cap. We introduce a numerical model in which the\nroot is modeled as a flexible self-elongating tube that probes a soil composed\nof solid particles. By means of extensive simulations, we show that the forces\nexerted on the root cap during its growth reflect interparticle force chains.\nOur extensive simulations also show that the mean force declines exponentially\nwith root flexibility, the highest force corresponding to the soil hardness.\nFurthermore, we find that this functional dependence is characterized by a\nsingle parameter that combines the granular structure and root bending\nstiffness. This finding will be useful to further address the biological issues\nof mechanosensing and thigmomorphogenesis in plant roots."
    },
    {
        "anchor": "Complex Self-Assembly from Simple Interaction Rules in Model Colloidal\n  Mixtures: Building structures with hierarchical order through the self-assembly of\nsmaller blocks is not only a prerogative of nature, but also a strategy to\ndesign artificial materials with tailored functions. We explore in simulation\nthe spontaneous assembly of colloidal particles into extended structures, using\nspheres and size-asymmetric dimers as solute particles, while treating the\nsolvent implicitly. Besides rigid cores for all particles, we assume an\neffective short-range attraction between spheres and small monomers to promote,\nthrough elementary rules, dimer-mediated aggregation of spheres. Starting from\na completely disordered configuration, we follow the evolution of the system at\nlow temperature and density, as a function of the relative concentration of the\ntwo species. When spheres and large monomers are of same size, we observe the\nonset of elongated aggregates of spheres, either disconnected or cross-linked,\nand a crystalline bilayer. As spheres grow bigger, the self-assembling scenario\nchanges, getting richer overall, with the addition of flexible membrane sheets\nwith crystalline order and monolayer vesicles. With this wide assortment of\nstructures, our model can serve as a viable template to achieve a better\ncontrol of self-assembly in dilute suspensions of microsized particles.",
        "positive": "Asymmetrical free diffusion with orientation-dependence of molecules in\n  finite timescales: Using molecular dynamics simulations, we show that free diffusion of a\nnanoscale particle (molecule) with asymmetric structure critically depends on\nthe orientation in a finite timescale of picoseconds to nanoseconds. In a\ntimescale of ~100 ps, there are ~10% more possibilities for the particle moving\nalong the initial orientation than moving opposite to the orientation; and the\ndiffusion distances of the particle reach ~1 nm. We find that the key to this\nobservation is the orientation-dependence of the damping force to the moving of\nthe nanoscale particle and a finite time is required to regulate the particle\norientation. This finding extends the work of Einstein to nano-world beyond\nrandom Brownian motion, thus will have a critical role in the understanding of\nthe nanoscale world."
    },
    {
        "anchor": "Method of image charges for describing linear deformation of bounded 2D\n  solid structures with circular holes and inclusions: We present a method for predicting the linear response deformation of finite\nand semi-infinite 2D solid structures with circular holes and inclusions by\nemploying the analogies with image charges and induction in electrostatics.\nCharges in electrostatics induce image charges near conductive boundaries and\nan external electric field induces polarization (dipoles, quadrupoles, and\nother multipoles) of conductive and dielectric objects. Similarly, charges in\nelasticity induce image charges near boundaries and external stress induces\npolarization (quadrupoles and other multipoles) inside holes and inclusions.\nStresses generated by these induced elastic multipoles as well as stresses\ngenerated by their images near boundaries then lead to interactions between\nholes and inclusions and with their images, which induce additional\npolarization and thus additional deformation of holes and inclusions. We\npresent a method that expands induced polarization in a series of elastic\nmultipoles, which systematically takes into account the interactions of\ninclusions and holes with the external field, between them, and with their\nimages. The results of our method for linear deformation of circular holes and\ninclusions near straight and curved boundaries show good agreement with both\nlinear finite element simulations and experiments.",
        "positive": "Topological versus rheological entanglement length in primitive path\n  analysis protocols: Primitive path analysis algorithms are now routinely employed to analyze\nentanglements in computer simulations of polymeric systems, but different\nanalysis protocols result in different estimates of the entanglement length,\nN_e. Here we argue that standard PPA measures the rheological entanglement\nlength, typically employed by tube models and relevant to quantitative\ncomparisons with experiment, while codes like Z or CReTA also determine the\ntopological entanglement length. For loosely entangled systems, a simple\nanalogy between between phantom networks and the mesh of entangled primitive\npaths suggests a factor of two between the two numbers. This result is in\nexcellent agreement with reported values for poly-ethylene, poly-butadiene and\nbead-spring polymer melts."
    },
    {
        "anchor": "Rheology of a supercooled polymer melt near an oscillating plate: an\n  application of multiscale modeling: The behavior of a supercooled polymer melt composed of short chains with ten\nbeads near an oscillating plate are simulated by using a hybrid simulation of\nmolecular dynamics (MD) and computational fluid dynamics (CFD). In the method,\nthe macroscopic dynamics are solved by using CFD, but, instead of using any\nconstitutive equations, a local stress is calculated by using a non-equilibrium\nMD simulation associated at each lattice node in the CFD calculation. It is\nseen that the local rheology of the melt varies considerably in a thin viscous\ndiffusion layer that arises near an oscillating plate. It is also found that\nthe local rheology of the melt is divided into the three different regimes,\ni.e., the viscous fluid, viscoelastic liquid, and viscoelastic solid regimes,\naccording to the local Deborah number $De$, which is defined with the Rouse or\n$\\alpha$ relaxation time, $\\tau_R$ or $\\tau_\\alpha$, and the angular frequency\nof the plate $\\omega$ as $De^R$=$\\omega\\tau_R$ or\n$De^\\alpha$=$\\omega\\tau_\\alpha$. The melt behaves as a viscous fluid when\n$De^R\\lesssim 1$, and the crossover between the liquid-like and solid-like\nregime takes place around $De^\\alpha\\simeq 1$.",
        "positive": "Dynamics of magnetic self-propelled particles in a harmonic trap: Artificial active particles, exemplified by Hexbugs (HB), serve as valuable\ntools for investigating the intricate dynamics of active matter systems.\nLeveraging their stochastic motion, Hexbugs provides an excellent experimental\nmodel. In this study, we utilize Hexbugs equipped with disk-like armor and\nembedded magnetic dipoles, transforming them into Magnetic Self-Propelled\nParticles (MSPP). We explore the emergence of collective and stationary states\nnumerically and experimentally by confining these MSPPs within a parabolic\ndomain acting as a harmonic potential. Our findings unveil a diverse range of\nmetastable configurations intricately linked to the complex dynamics inherent\nin the system. We discern that particle number, activity, and the balance\nbetween magnetic and harmonic potential strengths predominantly influence the\nmetastability of these structures. By employing these parameters as control\nfactors, we compare and contrast the behavior of MSPPs with disk-like magnetic\nActive Brownian Particles (ABPs) in the overdamped limit of vanishing inertia.\nOur numerical predictions reproduce most of the experimental observations,\nhighlighting the crucial role of magnetic dipole interactions in developing\nnovel configurations for active particles within parabolic domains. These\nconfigurations include chains, clusters, and vortex formations characterized by\na specific pattern in the particle spatial distribution. Notably, we observe\nthat the influence of inertia is not fundamental in generating metastable\nconfigurations in these confined systems. Instead, the particle's shape,\nactivity, and orientation are dominant factors. This comparative analysis\nprovides insights into the distinctive features and dynamics of MSPP within\nconfined environments, shedding light on the role of short-range polar\ninteractions."
    },
    {
        "anchor": "Polymer translocation: Effects of confinement: We investigate the influence of varying confinement on the dynamics of\npolymer translocation through a cone shaped channel. For this, a linear polymer\nchain is modeled by a self voiding walks (SAWs) on a square lattice. The\ncis-side of a cone-shaped channel has a finite volume, whereas the trans-side\nhas a semi-infinite space. The confining environment is varied either by\nchanging the position of the back wall while keeping the apex angle fixed or\naltering the apex angle while keeping the position of the back wall fixed. In\nboth cases, the effective space {\\phi}, which represents the number of monomers\nin a chain relative to the total number of accessible sites within the cone, is\nreduced due to the imposed confinement. Consequently, the translocation\ndynamics are affected. We analyze the entropy of the confined system as a\nfunction {\\phi}, which exhibits non-monotonic behaviour. We also calculate the\nfree energy associated with the confinement as a function of a virtual\ncoordinate for different positions of the back wall (base of the cone) along\nthe conical axis for various apex angles.Employing the Fokker-Planck equation,\nwe calculate the translocation time as a function of {\\phi} for different\nsolvent conditions across the pore. Our findings indicate that the\ntranslocation time decreases as {\\phi} increases, but it eventually reaches a\nsaturation point at a certain value of {\\phi}. Moreover, we highlight the\npossibility to control the translocation dynamics by manipulating the solvent\nquality across the pore. Furthermore, our investigation delves into the\nintricacies of polymer translocation through a cone-shaped channel, considering\nboth repulsive and neutral interactions with the pore wall. This exploration\nunveils nuanced dynamics and sheds light on the factors that significantly\nimpact translocation within confined channels.",
        "positive": "Energetics of single active diffusion trajectories: The fundamental insight into Brownian motion by Einstein is that all\nsubstances exhibit continual fluctuations due to thermal agitation balancing\nwith the frictional resistance. However, even at thermal equilibrium,\nbiological activity can give rise to non-equilibrium fluctuations that cause\n``active diffusion\" in living cells. Because of the non-stationary and\nnon-equilibrium nature of such fluctuations, mean square displacement analysis,\nrelevant only to a steady state ensemble, may not be the most suitable choice\nas it depends on the choice of the ensemble; hence, a new analytical method for\ndescribing active diffusion is desired. Here we discuss the stochastic\nenergetics of a thermally fluctuating single active diffusion trajectory driven\nby non-thermal random forces. Heat dissipation, usually difficult to measure,\ncan be estimated from the active diffusion trajectory; guidelines on the\nanalysis such as criteria for the time resolution and driving force intensity\nare shown by a statistical test. This leads to the concept of an\n``instantaneous diffusion coefficient\" connected to heat dissipation that may\nbe used to analyse the activity and molecular transport mechanisms of living\nsystems."
    },
    {
        "anchor": "Phase diagram of two-dimensional hard rods from fundamental mixed\n  measure density functional theory: A density functional theory for the bulk phase diagram of two-dimensional\norientable hard rods is proposed and tested against Monte Carlo computer\nsimulation data. In detail, an explicit density functional is derived from\nfundamental mixed measure theory and freely minimized numerically for hard\ndiscorectangles. The phase diagram, which involves stable isotropic, nematic,\nsmectic and crystalline phases, is obtained and shows good agreement with the\nsimulation data. Our functional is valid for a multicomponent mixture of hard\nparticles with arbitrary convex shapes and provides a reliable starting point\nto explore various inhomogeneous situations of two-dimensional hard rods and\ntheir Brownian dynamics.",
        "positive": "Hidden symmetries in jammed systems: There are deep, but hidden, geometric structures within jammed systems,\nassociated with hidden symmetries. These can be revealed by repeated\ntransformations under which these structures lead to fixed points. These\ngeometric structures can be found in the Voronoi tesselation of space defined\nby the packing. In this paper we examine two iterative processes: maximum\ninscribed sphere (MIS) inversion and a real-space coarsening scheme. Under\nrepeated iterations of the MIS inversion process we find invariant systems in\nwhich every particle is equal to the maximum inscribed sphere within its\nVoronoi cell. Using a real-space coarsening scheme we reveal behavior in\ngeometric order parameters which is length-scale invariant."
    },
    {
        "anchor": "Stalled phase transition model of high-elastic polymer: The microscopic model of semi-crystalline polymer in high-elastic state is\nproposed. The model is based on the assumption that, below the melting\ntemperature, the semi-crystalline polymer comprises crystal nuclei connected by\nstretched chain segments (SCS) with random configuration of monomers. The key\nfactor that stalls the phase transition below the melting temperature is the\ntension of the SCS. External stress applied to the polymer also shifts the\nequilibrium and causes unfolding of the nuclei, which enables large reversible\ndeformation of the polymer without loss of integrity. The simple 1D model\npredicts plateau in stress-strain curve of high-elastic polymer above the yield\nstress, which agrees with experimental observations. The model prediction for\nthe temperature dependence of polytetrafluoroethylene (PTFE) yield stress in\nhigh-elastic state is in satisfactory agreement with experiment.",
        "positive": "Cooperative effects driving the multi-periodic dynamics of cyclically\n  sheared amorphous solids: Plasticity in amorphous materials, such as glasses, colloids, or granular\nmaterials, is mediated by local rearrangements called \"soft spots\". Experiments\nand simulations have shown that soft spots are two-state entities interacting\nvia quadrupolar displacement fields generated when they switch states. When the\nsystem is subjected to cyclic strain driving, the soft spots can return to\ntheir original state after one or more forcing cycles. In this case, the system\nhas periodic dynamics and will always repeat the same microscopic states. Here\nwe focus on multi-periodic dynamics, i.e. dynamics that has periodicity larger\nthan the periodicity of the drive, and use a graph-theoretical approach to\nanalyze the dynamics obtained from numerical simulations. In this approach,\nmechanically stable configurations that transform purely elastically into each\nother over a range of applied strains, are represented by vertices, and plastic\nevents leading from one stable configuration to the other, are represented by\ndirected edges. An algorithm based on the graph topology and the displacement\nfields of the soft spots reveals that multi-periodic behavior results from the\nstates of some soft spots repeating after more than one period and provides\ninformation regarding the mechanisms that allow for such dynamics. To better\nunderstand the physical mechanisms behind multi-periodicity, we use a model of\ninteracting hysterons. Each hysteron is a simplified two-state element\nrepresenting hysteretic soft-spot dynamics. We identify several mechanisms for\nmulti-periodicity in this model, some involving direct interactions between\nmulti-periodic hysterons and another resulting from cooperative dynamics\ninvolving several hysterons. These cooperative events are naturally more common\nwhen more hysterons are present, thus explaining why multi-periodicity is more\nprevalent at large drive amplitudes."
    },
    {
        "anchor": "Transonic and supershear crack propagation driven by geometric\n  nonlinearities: Linear elastic fracture mechanics theory predicts that the speed of crack\ngrowth is limited by the Rayleigh wave speed. Although many experimental\nobservations and numerical simulations have supported this prediction, some\nexceptions have raised questions about its validity. The underlying reasons for\nthese discrepancies and the precise limiting speed of dynamic cracks remain\nunknown. Here, we demonstrate that tensile (mode~I) cracks can exceed the\nRayleigh wave speed and propagate at supershear speeds. We show that taking\ninto account geometric non-linearities, inherent in most materials, is\nsufficient to enable such propagation modes. These geometric non-linearities\nmodify the crack-tip singularity, resulting in different crack-tip opening\ndisplacements, cohesive zone behavior, and energy flows towards the crack tip.",
        "positive": "Feasibility of rational shape design of single-polymer micelle using\n  spontaneous surface curvature: Polymeric micelles are used in a variety of applications, with the micelle's\nshape often playing an important role. Consequently, a scheme to design\nmicelles of arbitrary shape is desirable. In this paper, we consider micelles\nformed from a single, linear, multiblock copolymer, and we study how easily the\nmicelle's shape can be controlled by altering the copolymer block lengths.\nUsing a rational design scheme, we identify a few aspects of the multiblock\ncomposition that are expected to have a well-behaved, predictable effect on\nmicelle shape. Starting from a reference micelle composition, itself already\nexhibiting a nonstandard shape having a moderately sized dimple, we alter these\naspects of the multiblock composition and observe the regularity of the micelle\nshape response. The response of the shape is found to be somewhat smooth, but\nsignificantly nonlinear and sometimes nonmonotonic, suggesting that\nsophisticated techniques may be required to aid in micelle design."
    },
    {
        "anchor": "Self-assembly in soft matter with multiple length scales: Spontaneous self-assembly in molecular systems is a fundamental route to both\nbiological and engineered soft matter. Simple micellisation, emulsion\nformation, and polymer mixing principles are well understood. However, the\nprinciples behind emergence of structures with competing length scales in soft\nmatter systems remain an open question. Examples include the\ndroplet-inside-droplet assembly in many biomacromolecular systems undergoing\nliquid-liquid phase separation, analogous multiple emulsion formation in\noil-surfactant-water formulations, and polymer core-shell particles with\ninternal structure. We develop here a microscopic theoretical model based on\neffective interactions between the constituents of a soft matter system to\nexplain self-organization both at single and multiple length scales. The model\nidentifies how spatial ordering at multiple length scales emerges due to\ncompeting interactions between the system components, e.g. molecules of\ndifferent sizes and different chemical properties. As an example of single and\nmultiple-length-scale assembly, we map out a generic phase diagram for a\nsolution with two solute species differing in their mutual and solvent\ninteractions. By performing molecular simulations on a block-copolymer system,\nwe further demonstrate how the phase diagram can be connected to a molecular\nsystem that has a transition from regular single-core polymer particles to\nmulti-core aggregates that exhibit multiple structural length scales. The\nfindings provide guidelines to understanding the length scales rising\nspontaneously in biological self-assembly, but also open new venues to the\ndevelopment and engineering of biomolecular and polymeric functional materials.",
        "positive": "The influence of water interfacial potentials on ion hydration free\n  energies and density profiles near the surface: The surface or contact potential at the water liquid-vapor interface is\ndiscussed in relation to determinations of absolute ion hydration free energies\nand distributions of ions near the interface. It is shown that, rather than the\nsurface potential itself, the net electrostatic potential at the center of an\nuncharged solute can aid both in relating differences between tabulations of\nhydration free energies and in explaining differing classical and quantum\nsurface potential estimates. Quantum mechanical results are consistent with\nconclusions from classical simulations that there is a net driving force that\nenhances anion density at the surface relative to cations."
    },
    {
        "anchor": "Energy surface and minimum energy paths for Fr\u00e9edericksz transitions\n  in bistable cholesteric liquid crystals: The multidimensional energy surface of a cholesteric liquid crystal in a\nplanar cell is investigated as a function of spherical coordinates determining\nthe director orientation. Minima on the energy surface correspond to the stable\nstates with particular director distribution. External electric and magnetic\nfields deform the energy surface and positions of minima. It can lead to the\ntransitions between states, known as the Fr\\'{e}edericksz effect. Transitions\ncan be continuous or discontinuous depending on parameters of the liquid\ncrystal which determine an energy surface. In a case of discontinuous\ntransition when a barrier between stable states is comparable with the thermal\nenergy, the activation transitions may occur and it leads to the modification\nof characteristics of the Fr\\'{e}edericksz effect with temperature without\nexplicit temperature dependencies of liquid crystal parameters. Minimum energy\npath between stable states on the energy surface for the Fr\\'{e}edericksz\ntransition is found using geodesic nudged elastic band method. Knowledge of\nthis path, which has maximal statistical weight among all other paths, gives\nthe information about a barrier between stable states and configuration of\ndirector orientation during the transition. It also allows one to estimate the\nstability of states with respect to the thermal fluctuations and their lifetime\nwhen the system is close to the Fr\\'{e}edericksz transition.",
        "positive": "Cascade process of vortex tangle dynamics in superfluid $^4$He without\n  mutual friction: Recently the Kelvin wave cascade process in superfluid $^4$He at very low\ntemperatures was discussed. In this mechanism, the dynamics of the waves on the\nvortex lines plays an important role. In order to investigate this mechanism,\nwe study numerically the dynamics of the waves on the reconnected vortex lines\nusing the full Biot-Savart law. This work shows the reconnection of two\nvortices leads to the waves on the reconnected vortex lines. To discuss the\nenergy of the waves on the vortex lines, the energy spectrum of the superflow\nbefore and after the reconnection is calculated."
    },
    {
        "anchor": "Ballistic propagation of density correlations and excess wall forces in\n  quenched granular media: We investigate a granular gas in a shaken quasi-two-dimensional box in\nmolecular dynamics computer simulations. After a sudden change (quench) of the\nshaking amplitude, transient density correlations are observed orders of\nmagnitude beyond the steady-state correlation length scale. Propagation of the\ncorrelations is ballistic, in contrast to recently investigated quenches of\nBrownian particles that show diffusive propagation [Rohwer et al., Phys. Rev.\nLett., 118, 015702 (2017), Rohwer et al., Phys. Rev. E, 97, 032125 (2018)]. At\nsufficiently strong cooling of the fluid the effect is overlaid by clustering\ninstability of the homogeneous cooling state with different scaling behavior.\nWe are able to identify different quench regimes. In each regime correlations\nexhibit remarkably universal position dependence. In simulations performed with\nside walls we find confinement effects for temperature and pressure in\nsteady-state simulations, and an additional transient wall pressure\ncontribution upon changing the shaking amplitude. The transient contribution is\nascribed to enhanced relaxation of the fluid in the presence of walls. From\nincompatible scaling behavior we conclude that the observed effects with and\nwithout side walls constitute distinct phenomena.",
        "positive": "Consistent treatment of hydrophobicity in protein lattice models\n  accounts for cold denaturation: The hydrophobic effect stabilizes the native structure of proteins by\nminimizing the unfavourable interactions between hydrophobic residues and water\nthrough the formation of a hydrophobic core. Here we include the entropic and\nenthalpic contributions of the hydrophobic effect explicitly in an implicit\nsolvent model. This allows us to capture two important effects: a length-scale\ndependence and a temperature dependence for the solvation of a hydrophobic\nparticle. This consistent treatment of the hydrophobic effect explains cold\ndenaturation and heat capacity measurements of solvated proteins."
    },
    {
        "anchor": "Hot Microswimmers: Hot microswimmers are self-propelled Brownian particles that exploit local\nheating for their directed self-thermophoretic motion. We provide a pedagogical\noverview of the key physical mechanisms underlying this promising new\ntechnology. It covers the hydrodynamics of swimming, thermophoresis and\n-osmosis, hot Brownian motion, force-free steering, and dedicated experimental\nand simulation tools to analyze hot Brownian swimmers.",
        "positive": "The linear viscoelastic fracture theory applies to soft solids better\n  when they are... viscoelastic: Over the last half-century, linear viscoelastic models for crack growth in\nsoft solids have flourished but comparisons of these models to experiments have\nremained scarce. In fact, most available models are either very approximate or\ncast in forms which are quite unsuitable for the analysis of actual data. Here\nwe propose a version of the linear viscoelastic rupture theory which is quite\namenable to data analysis. We then apply this approach to four sets of data\ndocumenting fracture in soft solids. For elastomers, the results reproduce the\nknown process zone size inconsistency. However, in two more viscoelastic\nsystems, the linear viscoelastic prediction was found to consistently match the\nmeasured velocity dependence of the rupture energy with physically acceptable\nprocess zone sizes. They even reasonably match the measured damage zone size.\nConsequences for more insightful analyzes of rupture data in soft solids are\ndiscussed."
    },
    {
        "anchor": "Steady-State Probe-Partitioning FRET: A Simple and Robust Tool for the\n  Study of Membrane Phase Behavior: An experimental strategy has been developed specifically for the study of\ncomposition-dependent phase behavior in multi-component artificial membranes.\nThe strategy is based on steady-state measurements of fluorescence resonance\nenergy transfer between freely diffusing membrane probe populations, and it is\nwell suited for the rapid generation of large data sets. Presented in this\npaper are the basic principles that guide the experiment's design, the\nderivation of an underlying mathematical model that serves to interpret the\ndata, and experimental results that confirm the model's predictive power.",
        "positive": "The Influence of Surface Topography and Surface Chemistry on the\n  Anti-Adhesive Performance of Nanoporous Monoliths: We designed spongy monoliths allowing liquid delivery to their surfaces\nthrough continuous nanopore systems (mean pore diameter ca. 40 nm). These\nnanoporous monoliths were flat or patterned with microspherical structures a\nfew 10 microns in diameter, and their surfaces consisted of aprotic polymer or\nof TiO2 coatings. Liquid may reduce adhesion forces FAd; possible reasons\ninclude screening of solid-solid interactions and poroelastic effects.\nSoftening-induced deformation of flat polymeric monoliths upon contact\nformation in the presence of liquids enhanced the work of separation WSe. On\nflat TiO2-coated monoliths, WSe was under wet conditions smaller than under dry\nconditions, possibly because of liquid-induced screening of solid-solid\ninteractions. Under dry conditions, WSe is larger on flat TiO2-coated monoliths\nthan on flat monoliths with polymeric surface. However, under wet conditions\nliquid-induced softening results in larger WSe on flat monoliths with polymeric\nsurface than on flat monoliths with oxidic surface. Monolithic microsphere\narrays show anti-adhesive properties; FAd and WSe are reduced by at least one\norder of magnitude as compared to flat nanoporous counterparts. On nanoporous\nmonolithic microsphere arrays, capillarity (WSe is larger under wet than under\ndry conditions) and solid-solid interactions (WSe is larger on oxide than on\npolymer) dominate contact mechanics. Thus, the microsphere topography reduces\nthe impact of softening-induced surface deformation and screening of\nsolid-solid interactions associated with liquid supply. Overall, simple\nmodifications of surface topography and chemistry combined with delivery of\nliquid to the contact interface allow adjusting WSe and FAd over at least one\norder of magnitude. (...)"
    },
    {
        "anchor": "Some observations on variational elasticity and its application to\n  plates and membranes: Energies and equilibrium equations for thin elastic plates are discussed,\nwith emphasis on several issues pertinent to recent approaches in soft\ncondensed matter. Consequences of choice of basis, choice of invariant strain\nmeasures, and of approximating material energies as purely geometric in nature,\nare detailed. Ambiguities in the definitions of energies based on small-strain\nexpansions, and in a typical informal process of dimensional reduction, are\nnoted. A simple example serves to demonstrate that a commonly used bending\nenergy has undesirable features, and it is suggested that a new theory based on\nBiot strains be developed. A compact form of the variation of a plate energy is\npresented. Throughout, the divergence form of equations is emphasized. An\nappendix relates the naive approach adopted in the main text with standard\nquantities in continuum mechanics.",
        "positive": "Frozen Cheerios effect: Particle-particle interaction induced by an\n  advancing solidification front: Particles at liquid interfaces have the tendency to cluster due to long-range\ncapillary interactions. This is known as the Cheerios effect. Here we\nexperimentally and theoretically study the interaction between two submerged\nparticles near an advancing water-ice interface during the freezing process.\nParticles that are more thermally conductive than water are observed to attract\neach other and form clusters once frozen. We call this feature the frozen\nCheerios effect. On the other hand, particles less conductive than water\nseparate, highlighting the importance of thermal conduction during freezing.\nBased on existing models for single particle trapping in ice, we develop an\nunderstanding of multiple particle interaction. We find that the overall\nstrength of the particle-particle interaction critically depends on the\nsolidification front velocity. Our theory explains why the thermal conductivity\nmismatch between the particles and water dictates the attractive/repulsive\nnature of the particle-particle interaction."
    },
    {
        "anchor": "Structure and thermodynamics of platelet dispersions: Various properties of fluids consisting of platelike particles differ from\nthe corresponding ones of fluids consisting of spherical particles because\ninteractions between platelets depend on their mutual orientations. One of the\nmain issues in this topic is to understand how structural properties of such\nfluids depend on factors such as the shape of the platelets, the size\npolydispersity, the orientational order, and the platelet number density. A\nstatistical mechanics approach to the problem is natural and in the last few\nyears there has been a lot of work on the study of properties of platelet\nfluids. In this contribution some recent theoretical developments in the field\nare discussed and experimental investigations are described.",
        "positive": "Soret Motion of a Charged Spherical Colloid: The thermophoretic motion of a charged spherical colloidal particle and its\naccompanying cloud of counterions and co-ions in a temperature gradient is\nstudied theoretically. Using the Debye-Huckel approximation, the Soret drift\nvelocity of a weakly charged colloid is calculated analytically. For highly\ncharged colloids, the nonlinear system of electrokinetic equations is solved\nnumerically, and the effects of high surface potential, dielectrophoresis, and\nconvection are examined. Our results are in good agreement with some of the\nrecent experiments on highly charged colloids without using adjustable\nparameters."
    },
    {
        "anchor": "Non-equilibrium dynamics of isostatic spring networks: Marginally stable systems exhibit rich critical mechanical behavior. Such\nisostatic assemblies can be driven out of equilibrium by internal activity, but\nit remains unclear how the isostatic and critical nature of such systems\naffects their non-equilibrium dynamics. Here, we investigate the influence of\nthe isostatic threshold on the non-equilibrium dynamics of active diluted\nspring networks. In our model, heterogeneously distributed active noise sources\ndrive the system into a non-equilibrium steady state. We quantify the\nnon-equilibrium dynamics of nearest-neighbor network nodes by the\ncharacteristic cycling frequency $\\omega$---a measure of the circulation of the\nassociated phase space currents. The distribution of these nearest-neighbor\ncycling frequencies exhibits critical scaling, which we describe using a\nmean-field approach. Overall, our work provides a theoretical approach to\nelucidate the role of marginality in active disordered systems.",
        "positive": "Thermodynamically Stable Knots in Semiflexible Polymers: Semiflexible polymers are widely used as a paradigm for understanding\nstructural phases in biomolecules including folding of proteins. Here, we\ncompare bead-spring and bead-stick variants of coarse-grained semiflexible\npolymer models that cover the whole range from flexible to stiff by conducting\nextensive replica-exchange Monte Carlo computer simulations. In the data\nanalysis we focus on knotted conformations whose stability is shown to depend\non the ratio $r_b/r_{\\rm min}$ with $r_b$ denoting the equilibrium bond length\nand $r_{\\rm min}$ the distance of the strongest nonbonded interactions. For\nboth models, our results provide evidence that at low temperatures for\n$r_b/r_{\\rm min}$ outside a small range around unity one always encounters\nknots as generic stable phases along with the usual frozen and bent-like\nstructures. By varying the bending stiffness, we observe rather strong\nfirst-order-like structural transitions between the coexisting phases\ncharacterized by these geometrically different motifs. Through analyses of the\nenergy distributions close to the transition point, we present exploratory\nestimates of the free-energy barriers between the coexisting phases."
    },
    {
        "anchor": "Constructing explicit magnetic analogies for the dynamics of glass\n  forming liquids: By defining a spatially varying replica overlap parameter for a supercooled\nliquid referenced to an ensemble of fiducial liquid state configurations we\nexplicitly construct a constrained replica free energy functional that maps\ndirectly onto an Ising Hamiltonian with both random fields and random\ninteractions whose statistics depend on liquid structure. Renormalization group\nresults for random magnets when combined with these statistics for the\nLennard-Jones glass suggest that discontinuous replica symmetry breaking would\noccur if a liquid with short range interactions could be equilibrated at a\nsufficiently low temperature where its mean field configurational entropy would\nvanish, even though the system strictly retains a finite configurational\nentropy.",
        "positive": "Curvature-driven stability of defects in nematic textures over spherical\n  disks: Stabilizing defects in liquid-crystal systems is crucial for many physical\nprocesses and applications ranging from functionalizing liquid-crystal textures\nto recently reported command of chaotic behaviors of active matters. In this\nwork, we perform analytical calculations to study the curvature driven\nstability mechanism of defects based on the isotropic nematic disk model that\nis free of any topological constraint. We show that in a growing spherical disk\ncovering a sphere the accumulation of curvature effect can prevent typical +1\nand +1/2 defects from forming boojum textures where the defects are repelled to\nthe boundary of the disk. Our calculations reveal that the movement of the\nequilibrium position of the +1 defect from the boundary to the center of the\nspherical disk occurs in a very narrow window of the disk area, exhibiting the\nfirst-order phase-transition-like behavior. For the pair of +1/2 defects by\nsplitting a +1 defect, we find the curvature driven alternating repulsive and\nattractive interactions between the two defects. With the growth of the\nspherical disk these two defects tend to approach and finally recombine towards\na +1 defect texture. The sensitive response of defects to curvature and the\ncurvature driven stability mechanism demonstrated in this work in nematic disk\nsystems may have implications towards versatile control and engineering of\nliquid crystal textures in various applications."
    },
    {
        "anchor": "Control of Stratification in Drying Particle Suspensions via Temperature\n  Gradients: A potential strategy for controlling stratification in a drying suspension of\nbidisperse particles is studied using molecular dynamics simulations. When the\nsuspension is maintained at a constant temperature during fast drying, it can\nexhibit \"small-on-top\" stratification with an accumulation (depletion) of\nsmaller (larger) particles in the top region of the drying film, consistent\nwith the prediction of current theories based on diffusiophoresis. However,\nwhen only the region near the substrate is thermalized at a constant\ntemperature, a negative temperature gradient develops in the suspension because\nof evaporative cooling at the liquid-vapor interface. Since the associated\nthermophoresis is stronger for larger nanoparticles, a higher fraction of\nlarger nanoparticles migrate to the top of the drying film at fast evaporation\nrates. As a result, stratification is converted to \"large-on-top\". Very strong\n\"small-on-top\" stratification can be produced with a positive thermal gradient\nin the drying suspension. Here we explore a way to produce a positive thermal\ngradient by thermalizing the vapor at a temperature higher than that of the\nsolvent. Possible experimental approaches to realize various thermal gradients\nin a suspension undergoing solvent evaporation, and thus to produce different\nstratification states in the drying film, are suggested.",
        "positive": "Cloaking by coating: How effectively does a thin, stiff coating hide a\n  soft substrate?: From human tissue to fruits, many soft materials are coated by a thin layer\nof a stiffer material. While the primary role of such a coating is often to\nprotect the softer material, the thin, stiff coating also has an important\neffect on the mechanical behaviour of the composite material, making it appear\nsignificantly stiffer than the underlying material. We study this cloaking\neffect of a coating for the particular case of indentation tests, which measure\nthe `firmness' of the composite solid: we use a combination of theory and\nexperiment to characterize the firmness quantitatively. We find that the\nindenter size plays a key role in determining the effectiveness of cloaking:\nsmall indenters feel a mixture of the material properties of the coating and of\nthe substrate, while large indenters sense largely the unadulterated substrate."
    },
    {
        "anchor": "On the stress and torque tensors in fluid membranes: We derive the membrane elastic stress and torque tensors using the standard\nHelfrich model and a direct variational method in which the edges of a membrane\nare infinitesimally translated and rotated. We give simple expressions of the\nstress and torque tensors both in the local tangent frame and in projection\nonto a fixed frame. We recover and extend the results of Capovilla and Guven\n[J. Phys. A, 2002, \\textbf{35}, 6233], which were obtained using covariant\ngeometry and Noether's theorem: we show that the Gaussian rigidity contributes\nto the torque tensor and we include the effect of a surface potential in the\nstress tensor. Many interesting situations may be investigated directly using\nforce and torque balances instead of full energy minimization. As examples, we\nconsider the force exerted at the end of a membrane tubule, membrane adhesion\nand domain contact conditions.",
        "positive": "Structure and Stability of Charged Colloid-Nanoparticle Mixtures: Physical properties of colloidal materials can be modified by addition of\nnanoparticles. Within a model of like-charged mixtures of particles governed by\neffective electrostatic interactions, we explore the influence of charged\nnanoparticles on the structure and thermodynamic phase stability of\ncharge-stabilized colloidal suspensions. Focusing on salt-free mixtures of\nparticles of high size and charge asymmetry, interacting via repulsive Yukawa\neffective pair potentials, we perform molecular dynamics simulations and\ncompute radial distribution functions and static structure factors. Analysis of\nthese structural properties indicates that increasing the charge and\nconcentration of nanoparticles progressively weakens correlations between\ncharged colloids. We show that addition of charged nanoparticles to a\nsuspension of like-charged colloids can induce a colloidal crystal to melt and\ncan facilitate aggregation of a fluid suspension due to attractive van der\nWaals interactions. We attribute the destabilizing influence of charged\nnanoparticles to enhanced screening of electrostatic interactions, which\nweakens repulsion between charged colloids. This interpretation is consistent\nwith recent predictions of an effective interaction theory of charged\ncolloid-nanoparticle mixtures."
    },
    {
        "anchor": "Strain fluctuations and elastic moduli in disordered solids: Recently there has been a surge in interest in using video-microscopy\ntechniques to infer the local mechanical properties of disordered solids. One\ncommon approach is to minimize the difference between particle vibrational\ndisplacements in a local coarse-graining volume and the displacements that\nwould result from a best-fit affine deformation. Effective moduli are then be\ninferred under the assumption that the components of this best-fit affine\ndeformation tensor have a Boltzmann distribution. In this paper, we combine\ntheoretical arguments with experimental and simulation data to demonstrate that\nthe above does not reveal information about the true elastic moduli of jammed\npackings and colloidal glasses.",
        "positive": "Differential equation for the flow rate of discharging silos based on\n  energy balance: Since the early work of Hagen in 1852 and Beverloo et al. in 1961, the flow\nrate of granular material discharging through a circular orifice from a silo\nhas been described by means of dimensional analysis and experimental fits, and\nexplained through the \"free fall arch\" model. Here, in contrast with the\ntraditional approach, we derive a differential equation based on the energy\nbalance of the system. This equation is consistent with the well known Beverloo\nrule thanks to a compensation of energy terms. Moreover, this new equation can\nbe used to explore new conditions for silo discharges. In particular, we show\nhow the effect of friction on the flow rate can be predicted. The theory is\nvalidated using discrete element method simulations."
    },
    {
        "anchor": "Effects of the Carnahan-Starling free energy within theories of fluids\n  with short-range attraction: Within the Free-Volume Asakura-Oosawa-Vrij (FVAO) theory of colloid-polymer\nmixtures, we show that unphysical gas-liquid binodals predicted in the regime\nof small attraction range (i.e. polymer size) are caused in part by the use of\nthe Carnahan-Starling (CS) hard sphere (HS) reference free energy. Replacement\nof the CS expression with an alternative dramatically affects predicted phase\nbehaviour and, for polydisperse colloid, the resultant fractionation\npredictions. Although short-range attractions render FVAO, as a perturbative\nHS-based theory, less accurate anyway, we argue that the particular effects of\nCS in this regime are an important consideration -- usually ignored -- in the\nevaluation of such theories. We refer to a variety of literature exhibiting\nsimilarly inaccurate gas-liquid binodals, and suggest CS's status as the de\nfacto choice of hard sphere reference should be carefully considered where\nshort-range attractions are present.",
        "positive": "Elastic energy of polyhedral bilayer vesicles: In recent experiments [M. Dubois, B. Dem\\'e, T. Gulik-Krzywicki, J.-C.\nDedieu, C. Vautrin, S. D\\'esert, E. Perez, and T. Zemb, Nature (London) Vol.\n411, 672 (2001)] the spontaneous formation of hollow bilayer vesicles with\npolyhedral symmetry has been observed. On the basis of the experimental\nphenomenology it was suggested [M. Dubois, V. Lizunov, A. Meister, T.\nGulik-Krzywicki, J. M. Verbavatz, E. Perez, J. Zimmerberg, and T. Zemb, Proc.\nNatl. Acad. Sci. U.S.A. Vol. 101, 15082 (2004)] that the mechanism for the\nformation of bilayer polyhedra is minimization of elastic bending energy.\nMotivated by these experiments, we study the elastic bending energy of\npolyhedral bilayer vesicles. In agreement with experiments, and provided that\nexcess amphiphiles exhibiting spontaneous curvature are present in sufficient\nquantity, we find that polyhedral bilayer vesicles can indeed be energetically\nfavorable compared to spherical bilayer vesicles. Consistent with experimental\nobservations we also find that the bending energy associated with the vertices\nof bilayer polyhedra can be locally reduced through the formation of pores.\nHowever, the stabilization of polyhedral bilayer vesicles over spherical\nbilayer vesicles relies crucially on molecular segregation of excess\namphiphiles along the ridges rather than the vertices of bilayer polyhedra.\nFurthermore, our analysis implies that, contrary to what has been suggested on\nthe basis of experiments, the icosahedron does not minimize elastic bending\nenergy among arbitrary polyhedral shapes and sizes. Instead, we find that, for\nlarge polyhedron sizes, the snub dodecahedron and the snub cube both have lower\ntotal bending energies than the icosahedron."
    },
    {
        "anchor": "Crack Propagation in Bone on the Scale of Mineralized Collagen Fibrils :\n  Role of Polymers with Sacrificial Bonds and Hidden Length: Sacrificial bonds and hidden length (SBHL) in structural molecules provide a\nmechanism for energy dissipation at the nanoscale. It is hypothesized that\ntheir presence leads to greater fracture toughness than what is observed in\nmaterials without such features. Here, we investigate this hypothesis using a\nsimplified model of a mineralized collagen fibril sliding on a polymeric\ninterface with SBHL systems. A 1D coarse-grained nonlinear spring-mass system\nis used to model the fibril. Rate-and-displacement constitutive equations are\nused to describe the mechanical properties of the polymeric system. The model\nquantifies how the interface toughness increases as a function of polymer\ndensity and number of sacrificial bonds. Other characteristics of the SBHL\nsystem, such as the length of hidden loops and the strength of the bonds, are\nfound to influence the results. The model also gives insight into the\nvariations in the mechanical behavior in response to physiological changes,\nsuch as the degree of mineralization of the collagen fibril and polymer density\nin the interfibrillar matrix. The model results provide constraints relevant\nfor bio-mimetic material design and multiscale modeling of fracture in human\nbone.",
        "positive": "On the thickness of the double layer in ionic liquids: In this study, we examined the thickness of the electrical double layer (EDL)\nin ionic liquids using density functional theory (DFT) calculations and\nmolecular dynamics (MD) simulations. We focused on the BF4- anion adsorption\nfrom 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) ionic liquid on\nthe Au(111) surface. At both DFT and MD levels, we evaluated the\ncapacitance-potential dependence for the Helmholtz model of the interface.\nUsing MD simulations, we also explored a more realistic, multilayer EDL model\naccounting for the ion layering. Concurrent analysis of the DFT and MD results\nprovides a ground for thinking whether the electrical double layer in ionic\nliquids is one- or multi-ionic-layer thick."
    },
    {
        "anchor": "Athermal shearing of frictionless cross-shaped particles of varying\n  aspect ratio: We use numerical simulations to study the shear-driven steady-state flow of\nathermal, frictionless, overdamped, two dimensional cross-shaped particles of\nvarying aspect ratios, and make comparison with the behavior of rod-shaped and\nstaple-shaped particles. We find that the extent of non-convexity of the\nparticle shape plays an important role in determining both the value of the\njamming packing fraction as well as the rotational motion and orientational\nordering of the particles.",
        "positive": "Matter-wave interferometry in periodic and quasi-periodic arrays: We calculate within a Bose-Hubbard tight-binding model the matter-wave flow\ndriven by a constant force through a Bose-Einstein condensate of Rb 87 atoms in\nvarious types of quasi-onedimensional arrays of potential wells. Interference\npatterns are obtained when beam splitting is induced by creating energy\nminigaps either through period doubling or through quasi-periodicity governed\nby the Fibonacci series. The generation of such condensate modulations by means\nof optical-laser structures is also discussed."
    },
    {
        "anchor": "Swimming Efficiently by Wrapping: Single flagellated bacteria are ubiquitous in nature. They exhibit various\nswimming modes using their flagella to explore complex surroundings such as\nsoil and porous polymer networks. Some single-flagellated bacteria swim with\ntwo distinct modes, one with its flagellum extended away from its body and\nanother with its flagellum wrapped around it. The wrapped mode has been\nobserved when the bacteria swim under tight confinements or in highly viscous\npolymeric melts. In this study we investigate the hydrodynamics of these two\nmodes inside a circular pipe. We find that the wrap mode is slower than the\nextended mode in bulk but more efficient under strong confinement due to a\nhydrodynamic increased of its flagellum translation-rotation coupling.",
        "positive": "Osmosis, from molecular insights to large-scale applications: Osmosis is a universal phenomenon occurring in a broad variety of processes\nand fields. It is the archetype of entropic forces, both trivial in its\nfundamental expression - the van 't Hoff perfect gas law - and highly subtle in\nits physical roots. While osmosis is intimately linked with transport across\nmembranes, it also manifests itself as an interfacial transport phenomenon: the\nso-called diffusio-osmosis and -phoresis, whose consequences are presently\nactively explored for example for the manipulation of colloidal suspensions or\nthe development of active colloidal swimmers. Here we give a global and\nunifying view of the phenomenon of osmosis and its consequences with a\nmulti-disciplinary perspective. Pushing the fundamental understanding of\nosmosis allows to propose new perspectives for different fields and we\nhighlight a number of examples along these lines, for example introducing the\nconcepts of osmotic diodes, active separation and far from equilibrium osmosis,\nraising in turn fundamental questions in the thermodynamics of separation. The\napplications of osmosis are also obviously considerable and span very diverse\nfields. Here we discuss a selection of phenomena and applications where osmosis\nshows great promises: osmotic phenomena in membrane science (with recent\ndevelopments in separation, desalination, reverse osmosis for water\npurification thanks in particular to the emergence of new nanomaterials);\napplications in biology and health (in particular discussing the kidney\nfiltration process); osmosis and energy harvesting (in particular, osmotic\npower and blue energy as well as capacitive mixing); applications in detergency\nand cleaning, as well as for oil recovery in porous media."
    },
    {
        "anchor": "Depletion potential in the infinite dilution limit: The depletion force and depletion potential between two in principle unequal\n\"big\" hard spheres embedded in a multicomponent mixture of \"small\" hard spheres\nare computed using the Rational Function Approximation method for the\nstructural properties of hard-sphere mixtures [S. B. Yuste, A. Santos, and M.\nL\\'opez de Haro, J. Chem. Phys. {\\bf 108}, 3683 (1998)]. The cases of equal\nsolute particles and of one big particle and a hard planar wall in a background\nmonodisperse hard-sphere fluid are explicitly analyzed. An improvement over the\nperformance of the Percus-Yevick theory and good agreement with available\nsimulation results are found",
        "positive": "Temporally heterogeneous dynamics in granular flows: Granular simulations are used to probe the particle scale dynamics at short,\nintermediate, and long time scales for gravity driven, dense granular flows\ndown an inclined plane. On approach to the angle of repose, where motion\nceases, the dynamics become intermittent over intermediate times, with strong\ntemporal correlations between particle motions -- temporally heterogeneous\ndynamics. This intermittency is characterised through large scale structural\nevents whereby the contact network periodically spans the system. A\ncharacteristic time scale associated with these processes increases as the\nstopped state is approached. These features are discussed in the context of the\ndynamics of supercooled liquids near the glass transition."
    },
    {
        "anchor": "The Surface Electroclinic Effect near the First Order\n  Smectic-A*--Smectic-C* transition: We analyze the surface electroclinic effect (SECE) in a material that\nexhibits a first order bulk smectic-$A^*$ (Sm-$A^*$) -- smectic-$C^*$\n(Sm-$C^*$) transition. The effect of a continuously varying degree of\nenantiomeric excess on the SECE is also investigated. We show that due to the\nfirst order nature of the bulk Sm-$A^*$ -- Sm-$C^*$ transition, the SECE can be\nunusually strong and that as enantiomeric excess is varied, a jump in surface\ninduced tilt is expected. A theoretical state map, in enantiomeric excess -\ntemperature space, features a critical point which terminates a line of first\norder discontinuities in the surface induced tilt. This critical point is\nanalogous to that found for the phase diagram (in electric field - temperature\nspace) for the bulk electroclinic effect. Analysis of the decay of the surface\ninduced tilt, as one moves from surface into bulk shows that for sufficiently\nhigh surface tilt the decay will exhibit a well defined spatial kink within\nwhich it becomes especially rapid. We also propose that the SECE is\nadditionally enhanced by the de Vries nature (i.e. small layer shrinkage at the\nbulk Sm-A* -- Sm-C* transition) of the material. As such the SECE provides a\nnew means to characterize the de Vries nature of a material. We discuss the\nimplications for using these materials in device applications and propose ways\nto investigate the predicted features experimentally.",
        "positive": "Mechanosensitive Channel Activation by Diffusio-Osmotic Force: For ion channel gating, the appearance of two distinct conformational states\nand the discrete transitions between them is essential, and therefore of\ncrucial importance to all living organisms. We show that the physical interplay\nbetween two structural elements that are commonly present in bacterial\nmechanosensitive channels, namely a charged vestibule and a hydrophobic\nconstriction, creates two distinct conformational states, open and closed, as\nwell as the gating between them. We solve the nonequilibrium\nStokes-Poisson-Nernst-Planck equations, extended to include a molecular\npotential of mean force, and show that a first order transition between the\nclosed and open states arises naturally from the diffusio-osmotic stress caused\nby the ions and water inside the channel and the elastic restoring force from\nthe membrane. Our proposed gating mechanism is likely to be important for a\nbroad range of ion channels, as well as for biomimetic channels and ion\nchannel-targeting therapeutics."
    },
    {
        "anchor": "Kohn's theorem in a superfluid Fermi gas with a Feshbach resonance: We investigate the dipole mode in a superfluid gas of Fermi atoms trapped in\na harmonic potential. According to Kohn's theorem, the frequency of this\ncollective mode is not affected by an interaction between the atoms and is\nalways equal to the trap frequency. This remarkable property, however, does not\nnecessarily hold in an approximate theory. We explicitly prove that the\nHartree-Fock-Bogoliubov generalized random phase approximation (HFB-GRPA),\nincluding a coupling between fluctuations in the density and Cooper channels,\nis consistent with both Kohn's theorem as well as Goldstone's theorem. This\nproof can be immediately extended to the strong-coupling superfluid theory\ndeveloped by Nozi\\'eres and Schmitt-Rink (NSR), where the effect of superfluid\nfluctuations is included within the Gaussian level. As a result, the NSR-GRPA\nformalism can be used to study collective modes in the BCS-BEC crossover region\nin a manner which is consistent with Kohn's theorem. We also include the effect\nof a Feshbach resonance and a condensate of the associated molecular bound\nstates. A detailed discussion is given of the unusual nature of the Kohn mode\neigenfunctions in a Fermi superfluid, in the presence and absence of a Feshbach\nresonance. When the molecular bosons feel a different trap frequency from the\nFermi atoms, the dipole frequency is shown to {\\it depend} on the strength of\neffective interaction associated with the Feshbach resonance.",
        "positive": "Short-time diffusion in concentrated bidisperse hard-sphere suspensions: Diffusion in bidisperse Brownian hard-sphere suspensions is studied by\nStokesian Dynamics (SD) computer simulations and a semi-analytical theoretical\nscheme for colloidal short-time dynamics, based on Beenakker and Mazur's method\n[Physica 120A, 388 (1983) & 126A, 349 (1984)]. Two species of hard spheres are\nsuspended in an overdamped viscous solvent that mediates the salient\nhydrodynamic interactions among all particles. In a comprehensive parameter\nscan that covers various packing fractions and suspension compositions, we\nemploy numerically accurate SD simulations to compute the initial diffusive\nrelaxation of density modulations at the Brownian time scale, quantified by the\npartial hydrodynamic functions. A revised version of Beenakker and Mazur's\n$\\delta\\gamma$-scheme for monodisperse suspensions is found to exhibit\nsurprisingly good accuracy, when simple rescaling laws are invoked in its\napplication to mixtures. The so-modified $\\delta\\gamma$ scheme predicts\nhydrodynamic functions in very good agreement with our SD simulation results,\nfor all densities from the very dilute limit up to packing fractions as high as\n$40\\%$."
    },
    {
        "anchor": "Roughness induced boundary slip in microchannel flows: Surface roughness becomes relevant if typical length scales of the system are\ncomparable to the scale of the variations as it is the case in microfluidic\nsetups. Here, an apparent boundary slip is often detected which can have its\norigin in the assumption of perfectly smooth boundaries. We investigate the\nproblem by means of lattice Boltzmann (LB) simulations and introduce an\n``effective no-slip plane'' at an intermediate position between peaks and\nvalleys of the surface. Our simulations show good agreement with analytical\nresults for sinusoidal boundaries, but can be extended to arbitrary geometries\nand experimentally obtained surface data. We find that the detected apparent\nslip is independent of the detailed boundary shape, but only given by the\ndistribution of surface heights. Further, we show that the slip diverges as the\namplitude of the roughness increases.",
        "positive": "Competition brings out the best: Modeling the frustration between\n  curvature energy and chain stretching energy of lyotropic liquid crystals in\n  bicontinuous cubic phases: It is commonly considered that the frustration between the curvature energy\nand the chain stretching energy plays an important role in the formation of\nlyotropic liquid crystals in bicontinuous cubic phases. Theoretic and numeric\ncalculations were performed for two extreme cases: Parallel surfaces eliminate\nthe variance of the chain length; constant mean curvature surfaces eliminate\nthe variance of the mean curvature. We have implemented a model with Brakke's\nSurface Evolver which allows a competition between the two variances. The\nresult shows a compromise of the two limiting geometries. With data from real\nsystems, we are able to recover the G--D--P phase sequence which was observed\nin experiments."
    },
    {
        "anchor": "The segregation of sheared binary fluids in the Bray-Humayun model: The phase separation process which follows a sudden quench inside the\ncoexistence region is considered for a binary fluid subjected to an applied\nshear flow. This issue is studied in the framework of the convection-diffusion\nequation based on a Ginzburg-Landau free energy functional in the approximation\nscheme introduced by Bray and Humayun [{\\it Phys.Rev.Lett.} {\\bf 68}, 1559,\n(1992)]. After an early stage where domains form and shear effects become\neffective the system enters a scaling regime where the typical domains sizes\n$L_\\parallel $, $L_\\perp$ along the flow and perpendicular to it grow as\n$t^{5/4}$ and $t^{1/4}$. The structure factor is characterized by the existence\nof four peaks, similarly to previous theoretical and experimental observations,\nand by exponential tails at large wavevectors.",
        "positive": "An Anisotropic Effective Model for the Simulation of Semiflexible Ring\n  Polymers: We derive and introduce anisotropic effective pair potentials to coarse-grain\nsolutions of semiflexible rings polymers of various lengths. The system has\nbeen recently investigated by means of full monomer-resolved computer\nsimulations, revealing a host of unusual features and structure formation,\nwhich, however, cannot be captured by a rotationally-averaged effective pair\npotential between the rings' centers of mass [M. Bernabei et al., Soft Matter\n9, 1287 (2013)]. Our new coarse-graining strategy is to picture each ring as a\nsoft, penetrable disc. We demonstrate that for the short- and\nintermediate-length rings the new model is quite capable of capturing the\nPhysics in a quantitative fashion, whereas for the largest rings, which\nresemble flexible ones, it fails at high densities. Our work opens the way for\nthe physical justification of general, anisotropic penetrable interaction\npotentials."
    },
    {
        "anchor": "Active interaction switching controls the dynamic heterogeneity of soft\n  colloidal dispersions: We employ Reactive Dynamical Density Functional Theory (R-DDFT) and Reactive\nBrownian Dynamics (R-BD) simulations to investigate the dynamics of a\nsuspension of active soft Gaussian colloids with binary interaction switching,\ni.e., a one-component colloidal system in which every particle stochastically\nswitches at predefined rates between two interaction states with different\nmobility. Using R-DDFT we extend a theory previously developed to access the\ndynamics of inhomogeneous liquids to study the influence of the switching\nactivity on the self and distinct part of the Van Hove function in bulk\nsolution, and determine the corresponding mean squared displacement of the\nswitching particles. Our results demonstrate that, even though the average\ndiffusion coefficient is not affected by the switching activity, it\nsignificantly modifies the non-equilibrium dynamics and diffusion coefficients\nof the individual particles, leading to a crossover from short to long times,\nwith a regime for intermediate times showing anomalous diffusion. In addition,\nthe self-part of the van Hove function has a Gaussian form at short and long\ntimes, but becomes non-Gaussian at intermediates ones, having a crossover\nbetween short and large displacements. The corresponding self-intermediate\nscattering function shows the two-step relaxation patters typically observed in\nsoft materials with heterogeneous dynamics such as glasses and gels. We also\nintroduce a phenomenological Continuous Time Random Walk (CTRW) theory to\nunderstand the heterogeneous diffusion of this system. R-DDFT results are in\nexcellent agreement with R-BD simulations and the analytical predictions of\nCTRW theory, thus confirming that R-DDFT constitutes a powerful method to\ninvestigate not only the structure and phase behavior, but also the dynamical\nproperties of non-equilibrium active switching colloidal suspensions.",
        "positive": "Ratchet effects for paramagnetic beads above striped ferrite-garnet\n  films: We calculate the motion of a small paramagnetic bead which is manipulated by\nthe stripe domain pattern of a ferrite-garnet film. A model for the bead's\nmotion in a liquid above the film is developed and used to look for ratchet\nsolutions, where the bead acquires net coherent motion in one direction when\nthe external field is modulated periodically. We consider three cases. First,\nthe ratchet, where the beads all go in the same direction. Second, the height\ndependent ratchet, where beads at different heights go in opposite direction.\nThis case can be used to separate beads of different sizes, as considered in J.\nPhys. Chem. B 112, 3833 (2008). Third, we describe how the separation threshold\ncan be tuned by changing the amplitude of the applied field. Finally, we\ndescribe a pseudo ratchet, where the external modulation is not periodic and\nthe ratchet changes direction periodically."
    },
    {
        "anchor": "A geometric-Structure Theory for maximally Random Jammed Packings: Maximally random jammed (MRJ) particle packings can be viewed as prototypical\nglasses in that they are maximally disordered while simultaneously being\nmechanically rigid. The prediction of the MRJ packing density phi, among other\npacking properties of frictionless particles, still poses many theoretical\nchallenges, even for congruent spheres or disks. Using the geometric-structure\napproach, we derive for the first time a highly accurate formula for MRJ\ndensities for a very wide class of twodimensional frictionless packings,\nnamely, binary convex superdisks, with shapes that continuously interpolate\nbetween circles and squares.",
        "positive": "Surface waves in deformed Bell materials: Small amplitude inhomogeneous plane waves are studied as they propagate on\nthe free surface of a predeformed semi-infinite body made of Bell constrained\nmaterial. The predeformation corresponds to a finite static pure homogeneous\nstrain. The surface wave propagates in a principal direction of strain and is\nattenuated in another principal direction, orthogonal to the free surface. For\nthese waves, the secular equation giving the speed of propagation is\nestablished by the method of first integrals. This equation is not the same as\nthe secular equation for incompressible half-spaces, even though the Bell\nconstraint and the incompressibility constraint coincide in the isotropic\ninfinitesimal limit."
    },
    {
        "anchor": "Static and Dynamic Properties of Block-Copolymer Based Grafted\n  Nanoparticles Across the Non-Ergodicity Transition: We present a systematic investigation of static and dynamic properties of\nblock copolymer micelles with crosslinked cores, representing model\npolymer-grafted nanoparticles, over a wide concentration range from dilute\nregime to an arrested (crystalline) state, by means of light and neutron\nscattering, complemented by linear viscoelasticity. We have followed the\nevolution of their scattering intensity and diffusion dynamics throughout the\nnon-ergodicity transition and the observed results have been contrasted against\nappropriately coarse-grained Langevin Dynamics simulations. These stable model\nsoft particles of the core-shell type are situated between ultrasoft stars and\nhard spheres, and the well-known star pair interaction potential is not\nappropriate to describe them. Instead, we have found that an effective brush\ninteraction potential provides very satisfactory agreement between experiments\nand simulations, offering insights into the interplay of softness and dynamics\nin spherical colloidal suspensions.",
        "positive": "Persistence length of a polyelectrolyte in salty water: a Monte-Carlo\n  study: We address the long standing problem of the dependence of the electrostatic\npersistence length $l_e$ of a flexible polyelectrolyte (PE) on the screening\nlength $r_s$ of the solution within the linear Debye-Huckel theory. The\nstandard Odijk, Skolnick and Fixman (OSF) theory suggests $l_e \\propto r_s^2$,\nwhile some variational theories and computer simulations suggest $l_e \\propto\nr_s$. In this paper, we use Monte-Carlo simulations to study the conformation\nof a simple polyelectrolyte. Using four times longer PEs than in previous\nsimulations and refined methods for the treatment of the simulation data, we\nshow that the results are consistent with the OSF dependence $l_e \\propto\nr_s^2$. The linear charge density of the PE which enters in the coefficient of\nthis dependence is properly renormalized to take into account local\nfluctuations."
    },
    {
        "anchor": "The ordered and orientationally disordered crystalline phases of the\n  flexible C4F8 molecule: There is ample experimental evidence on the existence of several crystalline\nphases of C4F8, although they still have been not clearly identified. In this\npaper we perform a series of molecular dynamics (MD) simulations using a\npartially flexible molecular model, which takes into account the mixing of the\nlow frequency intramolecular modes and lattice modes. The calculations are\ncarried on in the constant pressure- constant temperature ensemble and the\nalgorithm employed allows volume and symmetry changes of the MD sample as a\nfunction of thermodynamic variables. Although several stable crystalline phases\nare found, their number is still less than found by experiments.",
        "positive": "Rupture processes in fiber bundle models: Fiber bundles with statistically distributed thresholds for breakdown of\nindividual fibers are interesting models of the static and dynamics of failures\nin materials under stress. They can be analyzed to an extent that is not\npossible for more complex materials. During the rupture process in a fiber\nbundle avalanches, in which several fibers fail simultaneously, occur. We study\nby analytic and numerical methods the statistics of such avalanches, and the\nbreakdown process for several models of fiber bundles. The models differ\nprimarily in the way the extra stress caused by a fiber failure is\nredistributed among the surviving fibers."
    },
    {
        "anchor": "Non-monotonic electrophoretic mobility of rod-like polyelectrolytes by\n  multivalent coions in added salt: It is well established that when multivalent counterions or salts are added\nto a solution of highly-charged polyelectrolytes (PEs), correlation effects can\ncause charge inversion of the PE, leading to electrophoretic mobility (EM)\nreversal. In this work, we use coarse-grained molecular dynamics simulations to\nunravel the less understood effect of coion valency on EM reversal for rigid\nDNA-like PEs. We find that EM reversal induced by multivalent counterions is\nsuppressed with increasing coion valency in the salt added and eventually\nvanishes. Further, we find that EM is enhanced at fixed low salt concentrations\nfor salts with monovalent counterions when multivalent coions with increasing\nvalency are introduced. However, increasing the salt concentration causes a\ncrossover that leads to EM reversal which is enhanced by increasing coion\nvalency at high salt concentration. Remarkably, this multivalent coion-induced\nEM reversal persists even for low values of PE linear charge densities where\nmultivalent counterions alone cannot induce EM reversal. These results\nfacilitate tuning PE-PE interactions and self-assembly with both coion and\ncounterion valencies.",
        "positive": "Density effects in entangled solutions of linear and ring polymers: In this paper, we employ Molecular Dynamics computer simulations to study and\ncompare the statics and dynamics of linear and circular (ring) polymer chains\nin entangled solutions of different densities. While we confirm that linear\nchain conformations obey Gaussian statistics at all densities, rings tend to\ncrumple becoming more and more compact as density increases. Conversely,\ncontact frequencies between chain monomers are shown to depend on solution\ndensity for both chain topologies. Relaxation of chains at equilibrium is also\nshown to depend on topology, with ring polymers relaxing faster than their\nlinear counterparts. Finally, we discuss the local viscoelastic properties of\nthe solutions by showing that diffusion of dispersed colloid-like particles is\nmarkedly faster in the rings case."
    },
    {
        "anchor": "Universal Scaling Behaviors of Entangled Polymer Melts at High-stress\n  Shear: In addition to the terminal flow (the region I) and the shear thinning (the\nregion II), we discover two new flow regions in capillary flow at the wall\nstress higher than the plateau modulus of the polymer. The region III violates\nthe empirical Cox-Merz rule with a significantly weaker shear thinning than the\nregion II, and the region IV exhibits unexpected shear thickening. Moreover,\nthe crossover shear rates between the regions II and III and between the\nregions III and IV scale with the number of entanglement per chain, Z=M_w/M_e,\nas Z^(-2.0) and Z^(-1.2) respectively. We attribute the weakening in shear\nthinning and the emergence of shear thickening to the deformation-induced\nnon-Gaussian stretching of polymers. These observations offer the first\nexperimental quantification of the deformation behaviors of polymer melts at\nhigh-stress shear.",
        "positive": "Scaling law of the drag force in dense granular media: Making use of the system of pulling a spherical intruder in static\nthree-dimensional granular media, we numerically study the scaling law for the\ndrag force $F_{\\rm drag}$ acting on the moving intruder under the influence of\nthe gravity. Suppose if the intruder of diameter $D$ immersed in a granular\nmedium consisting of grains of average diameter $d$ is located at a depth $h$\nand moves with a speed $V$, we find that $F_{\\rm drag}$ can be scaled as\n$(D+d)^{\\phi_\\mu} h^{\\alpha_\\mu}$ with two exponents $\\phi_\\mu$ and\n$\\alpha_\\mu$, which depend on the friction coefficient $\\mu$ and satisfy an\napproximate sum rule $\\phi_\\mu+\\alpha_\\mu\\approx 3$. This scaling law is valid\nfor the arbitrary Froude number (defined by $\\mathrm{Fr}={2\nV}\\sqrt{{2D}/{g}}\\big/(D+d)$), if $h$ is sufficiently deep. We also identify\nthe existence of three regimes (quasistatic, linear, and quadratic) at least\nfor frictional grains in the velocity dependence of drag force. The crossovers\ntake place at $\\mathrm{Fr}\\approx 1$ between the quasistatic to the linear\nregimes and at $\\mathrm{Fr}\\approx 5$ between the linear to the quadratic\nregimes. We also observe that Froude numbers at which these crossovers between\nthe regimes happen are independent of the depth $h$ and the diameter of the\nintruder $D$. We also report the numerical results on the average coordination\nnumber of the intruder and average contact angle as functions of intruder\nvelocity."
    },
    {
        "anchor": "Long-ranged order and flow alignment in sheared $p-$atic liquid crystals: We formulate a hydrodynamic theory of $p-$atic liquid crystals, namely\ntwo-dimensional anisotropic fluids endowed with generic $p-$fold rotational\nsymmetry. Our approach, based on an order parameter tensor that directly\nembodies the discrete rotational symmetry of $p-$atic phases, allows us to\nunveil several unknown aspects of flowing $p-$atics, that previous theories,\ncharacterized by ${\\rm O(2)}$ rotational symmetry, could not account for. This\nincludes the onset of long-ranged orientational order in the presence of a\nsimple shear flow of arbitrary shear rate, as opposed to the standard\nquasi-long-ranged order of two-dimensional liquid crystals, and the possibility\nof flow alignment at large shear rates.",
        "positive": "Macroscopic behavior of bidisperse suspensions of noncolloidal particles\n  in yield stress fluids: We study both experimentally and theoretically the rheological behavior of\nisotropic bidisperse suspensions of noncolloidal particles in yield stress\nfluids. We focus on materials in which noncolloidal particles interact with the\nsuspending fluid only through hydrodynamical interactions. We observe that both\nthe elastic modulus and yield stress of bidisperse suspensions are lower than\nthose of monodisperse suspensions of same solid volume fraction. Moreover, we\nshow that the dimensionless yield stress of such suspensions is linked to their\ndimensionless elastic modulus and to their solid volume fraction through the\nsimple equation of Chateau et al.[J. rheol. 52, 489-506 (2008)]. We also show\nthat the effect of the particle size heterogeneity can be described by means of\na packing model developed to estimate random loose packing of assemblies of dry\nparticles. All these observations finally allow us to propose simple closed\nform estimates for both the elastic modulus and the yield stress of bidisperse\nsuspensions: while the elastic modulus is a function of the reduced volume\nfraction $\\phi/\\phi_m$ only, where $\\phi_m$ is the estimated random loose\npacking, the yield stress is a function of both the volume fraction $\\phi$ and\nthe reduced volume fraction."
    },
    {
        "anchor": "Distinguishing nanobubbles from nanodroplets with AFM: the influence of\n  vertical and lateral imaging forces: The widespread application of surface-attached nanobubbles and nanodroplets\nin biomedical engineering and nanotechnology is limited by numerous\nexperimental challenges, in particular, the possibility of contamination in\nnucleation experiments. These challenges are complicated by recent reports that\nit can be difficult to distinguish between nanoscale drops and bubbles. Here we\nidentify clear differences in the mechanical responses of nanobubbles and\nnanodroplets under various modes of AFM imaging which subject the objects to\npredominantly vertical or lateral forces. This allows to distinguish between\nnanodroplets, nanobubbles, and oil covered nanobubbles in water.",
        "positive": "Reversible gelation and dynamical arrest of dipolar colloids: We use molecular dynamics simulations of a simple model to show that\ndispersions of slightly elongated colloidal particles with long-range dipolar\ninteractions, like ferrofluids, can form a physical (reversible) gel at low\nvolume fractions. On cooling, the particles first self-assemble into a\ntransient percolating network of cross-linked chains, which, at much lower\ntemperatures, then undergoes a kinetic transition to a dynamically arrested\nstate with broken ergodicity. This transition from a transient to a frozen gel\nis characterised by dynamical signatures reminiscent of jamming in much denser\ndispersions."
    },
    {
        "anchor": "Ab-initio Structure and Thermodynamics of the RPBE-D3 Water/Vapor\n  Interface by Neural-Network Molecular Dynamics: Aided by a neural network representation of the density functional theory\n(DFT) potential energy landscape of water in the RPBE approximation corrected\nfor dispersion, we calculate several structural and thermodynamic properties of\nits liquid/vapor interface. The neural network speed allows us to bridge the\nsize and time scale gaps required to sample the properties of water along its\nliquid/vapor coexistence line with unprecedented precision.",
        "positive": "Motion-reversal in a simple microscopic swimmer: We study the motion of a microscopic swimmer composed of a semiflexible\npolymer anchored at the surface of a magnetic sphere using hydrodynamic\nsimulations and scaling arguments. The swimmer is driven by a rotating magnetic\nfield, and displays forward and backward motion depending on the value of the\nrotational frequency. In particular, the system exhibits forward thrust for\nfrequencies below a critical frequency $\\omega^*$, while above $\\omega^*$ the\nmotion is reversed."
    },
    {
        "anchor": "Understanding the shear modulus of dense microgel suspensions: Polymer microgels exhibit intriguing macroscopic flow properties arising from\ntheir unique microscopic structure. Microgel colloids comprise a crosslinked\npolymer network with a radially decaying density profile, resulting in a dense\ncore surrounded by a fuzzy corona. Notably, microgels synthesized from\npoly(N-isopropylacrylamide) (PNIPAM) are thermoresponsive, capable of adjusting\ntheir size and density profile based on temperature. Above the lower critical\nsolution temperature ($T_\\text{LCST}\\sim 33$ $^\\circ$C), the microgel's polymer\nnetwork collapses, leading to the expulsion of water through a reversible\nprocess. Conversely, below $33$ $^\\circ$C, the microgel's network swells,\nbecoming highly compressible and allowing overpacking to effective volume\nfractions exceeding one. Under conditions of dense packing, microgels undergo\ndeformation in distinct stages: corona compression and faceting,\ninterpenetration, and finally, isotropic compression. Each stage exhibits a\ncharacteristic signature in the yield stress and elastic modulus of the dense\nmicrogel suspensions. Here, we introduce a model for the linear elastic shear\nmodulus through the minimization of a quasi-equilibrium free energy,\nencompassing all relevant energetic contributions. We validate our model by\ncomparing its predictions to experimental results from oscillatory shear\nrheology tests on microgel suspensions at different densities and temperatures.\nOur findings demonstrate that combining macroscopic rheological measurements\nwith the model allows for temperature-dependent characterization of polymer\ninteraction parameters.",
        "positive": "Surface tension and the strain-dependent topography of soft solids: When stretched in one direction, most solids shrink in the transverse\ndirections. In soft silicone gels, however, we observe that small-scale\ntopographical features grow upon stretching. A quantitative analysis of the\ntopography shows that this counter-intuitive response is nearly linear,\nallowing us to tackle it through a small-strain analysis. We find that the\nsurprising increase of small-scale topography with stretch is due to a delicate\ninterplay of the bulk and surface responses to strain. Specifically, we find\nthat surface tension changes as the material is deformed. This response is\nexpected on general grounds for solid materials, but challenges the standard\ndescription of gel- and elastomer-surfaces."
    },
    {
        "anchor": "Long-Range Anomalous Decay of the Correlation in Jammed Packings: We numerically study the structure of the interactions occurring in\nthree-dimensional systems of hard spheres at jamming, focusing on the\nlarge-scale behavior. Given the fundamental role they play in the configuration\nof jammed packings, we analyze the propagation through the system of the weak\nforces and of the variation of the coordination number with respect to the\nisostaticity condition $\\Delta Z$. We show that these correlations can be\nsuccessfully probed by introducing a correlation function weighted on the\ndensity-density fluctuations. The results of this analysis can be further\nimproved by introducing a representation of the system based on the contact\npoints between particles. In particular, we find evidence that the weak forces\nand the $\\Delta Z$ fluctuations support the hypothesis of randomly jammed\npackings of spherical particles being hyperuniform by exhibiting an anomalous\nlong-range decay. Moreover, we find that the large-scale structure of the\ndensity-density correlation exhibits a complex behavior due to the\nsuperimposition of two exponentially damped oscillating signals propagating\nwith linearly depending frequencies.",
        "positive": "Stability of Pinned Surface Nanobubbles Against Expansion: Insights from\n  Theory and Simulation: While growth and dissolution of surface nanobubbles has been widely studied\nin recent years, their stability under pressure changes or a temperature\nincrease has not received the same level of scrutiny. Here, we present\ntheoretical predictions based on classical theory for pressure and temperature\nthresholds ($p_c$ and $T_c$) at which unstable growth occurs for the case of\nair nanobubbles on a solid surface in water. We show that bubbles subjected to\npinning have much lower $p_c$ and higher $T_c$ compared to both unpinned and\nbulk bubbles of similar size, indicating that pinned bubbles can withstand a\nlarger tensile stress (negative pressure) and higher temperatures. The values\nof $p_c$ and $T_c$ obtained from many-body dissipative particle dynamics (MDPD)\nsimulations of quasi-two-dimensional (quasi-2D) surface nanobubbles are\nconsistent with the theoretical predictions, provided that the lateral\nexpansion during growth is taken into account. This suggests that the modified\nclassical thermodynamic description is valid for pinned bubbles as small as\nseveral nanometers. While some discrepancies still exist between our\ntheoretical results and previous experiments, further experimental data is\nneeded before a comprehensive understanding of the stability of surface\nnanobubbles can be achieved."
    },
    {
        "anchor": "Local Order Metrics for Two-Phase Media Across Length Scales: The capacity to devise order metrics for microstructures of multiphase\nheterogeneous media is a highly challenging task, given the richness of the\npossible geometries and topologies of the phases that can arise. This\ninvestigation initiates a program to formulate order metrics to characterize\nthe degree of order/disorder of the microstructures of two-phase media in\n$d$-dimensional Euclidean space $\\mathbb{R}^d$ across length scales. In\nparticular, we propose the use of the local volume-fraction variance\n$\\sigma^2_{_V}(R)$ associated with a spherical window of radius $R$ as an order\nmetric. We determine $\\sigma^2_{_V}(R)$ as a function of $R$ for 22 different\nmodels across the first three space dimensions, including both hyperuniform and\nnonhyperuniform systems with varying degrees of short- and long-range order. We\nfind that the local volume-fraction variance as well as asymptotic coefficients\nand integral measures derived from it provide reasonably robust and sensitive\norder metrics to categorize disordered and ordered two-phase media across all\nlength scales.",
        "positive": "Internal friction controls active ciliary oscillations near the\n  instability threshold: Ciliary oscillations driven by molecular motors cause fluid motion at micron\nscale. Stable oscillations require a substantial source of dissipation to\nbalance the energy input of motors. Conventionally, it stems from external\nfluid. We show, in contrast, that external fluid friction is negligible\ncompared to internal elastic stress through a simultaneous measurement of\nmotion and flow field of an isolated and active Chlamydomonas cilium beating\nnear the instability threshold. Consequently, internal friction emerges as the\nsole source of dissipation for ciliary oscillations. We combine these\nexperimental insights with theoretical modeling of active filaments to show\nthat an instability to oscillations takes place when active stresses are strain\nsoftening and shear thinning. Together, our results reveal a counterintuitive\nmechanism of ciliary beating and provide a general experimental and theoretical\nmethodology to analyze other active filaments, both biological and synthetic\nones."
    },
    {
        "anchor": "Shear modulus of simulated glass-forming model systems: Effects of\n  boundary condition, temperature and sampling time: The shear modulus G of two glass-forming colloidal model systems in d=3 and\nd=2 dimensions is investigated by means of, respectively, molecular dynamics\nand Monte Carlo simulations. Comparing ensembles where either the shear strain\ngamma or the conjugated (mean) shear stress tau are imposed, we compute G from\nthe respective stress and strain fluctuations as a function of temperature T\nwhile keeping a constant normal pressure P. The choice of the ensemble is seen\nto be highly relevant for the shear stress fluctuations mu_F(T) which at\nconstant tau decay monotonously with T following the affine shear elasticity\nmu_A(T), i.e. a simple two-point correlation function. At variance,\nnon-monotonous behavior with a maximum at the glass transition temperature T_g\nis demonstrated for mu_F(T) at constant gamma. The increase of G below T_g is\nreasonably fitted for both models by a continuous cusp singularity, G(T) is\nproportional to (1-T/T_g)^(1/2), in qualitative agreement with some recent\nreplica calculations. It is argued, however, that longer sampling times may\nlead to a sharper transition. The additive jump discontinuity predicted by\nmode-coupling theory and other replica calculations thus cannot ultimately be\nruled out.",
        "positive": "Precursor films in wetting phenomena: The spontaneous spreading of non-volatile liquid droplets on solid substrates\nposes a classic problem in the context of wetting phenomena. It is well known\nthat the spreading of a macroscopic droplet is in many cases accompanied by a\nthin film of macroscopic lateral extent, the so-called precursor film, which\nemanates from the three-phase contact line region and spreads ahead of the\nlatter with a much higher speed. Such films have been usually associated with\nliquid-on-solid systems, but in the last decade similar films have been\nreported to occur in solid-on-solid systems. While the situations in which the\nthickness of such films is of mesoscopic size are rather well understood, an\nintriguing and yet to be fully understood aspect is the spreading of\nmicroscopic, i.e., molecularly thin films. Here we review the available\nexperimental observations of such films in various liquid-on-solid and\nsolid-on-solid systems, as well as the corresponding theoretical models and\nstudies aimed at understanding their formation and spreading dynamics. Recent\ndevelopments and perspectives for future research are discussed."
    },
    {
        "anchor": "Liquid morphologies and capillary forces between three spherical beads: Equilibrium shapes of coalesced pendular bridges in a static assembly of\nspherical beads are computed by numerical minimization of the interfacial\nenergy. Our present study focuses on generic bead configurations involving\nthree beads, one of which is in contact to the two others while there is a gap\nof variable size between the latter. In agreement with previous experimental\nstudies, we find interfacial `trimer' morphologies consisting of three\ncoalesced pendular bridges, and `dimers' of two coalesced bridges. In a certain\nrange of the gap opening we observe a bistability between the dimer and trimer\nmorphology during shrinking and growth. The magnitude of the corresponding\ncapillary forces in presence of a trimer or dimer depends, besides the gap\nopening only on the volume or Laplace pressure of liquid. For a given Laplace\npressure, the capillary forces in presence of a trimer are slightly larger than\nthe force of a single bridges at the same gap opening, which could explain the\nshallow maximum and plateau of the capillary cohesion of a wetting liquid for\nsaturations in the funicular regime.",
        "positive": "Frequency-dependent fluctuation-dissipation relations in granular gases: The Green-Kubo relation for two models of granular gases is discussed. In the\nMaxwell model in any dimension, the effective temperature obtained from the\nGreen-Kubo relation is shown to be frequency independent, and equal to the\naverage kinetic energy, known as the granular temperature. In the second model\nanalyzed, a mean-field granular gas, the collision rate of a particle is taken\nto be proportional to its velocity. The Green-Kubo relation in the high\nfrequency limit is calculated for this model, and the effective temperature in\nthis limit is shown to be equal to the granular temperature. This result, taken\ntogether with previous results, showing a difference between the effective\ntemperature at zero frequency (the Einstein relation) and the granular\ntemperature, shows that the Green-Kubo relation for granular gases is violated."
    },
    {
        "anchor": "Extreme Contractility and Torsional Compliance of Soft Ribbons under\n  High Twist: We investigate experimentally and model the mechanical response of a soft\nHookean ribbon submitted to large twist $\\eta$ and longitudinal tension $T$,\nunder clamped boundary conditions. We derive a formula for the torque $M$ using\nthe \\FvK equations up to third order in twist, incorporating a twist-tension\ncoupling. In the stable helicoid regime, quantitative agreement with\nexperimental data is obtained. When twisted above a critical twist $\\eta_L(T)$,\nribbons develop wrinkles and folds which modify qualitatively the mechanical\nbehavior. We show a surprisingly large longitudinal contraction upon twist,\nreminiscent of a Poynting effect, and a much lower torsional stiffness. Far\nfrom threshold, we identify two regimes depending on the applied $T$. In a\nhigh-$T$ regime, we find that the torque scales as $\\eta\\cdot T$ and the\ncontraction as $\\eta^2$, in agreement with a far from threshold analysis where\ncompression and bending stresses are neglected. In a low-$T$ regime, the\ncontraction still scales as $\\eta^2$ but the torque appears $T$-independent and\nlinear with $\\eta$. We argue that the large curvature of the folds now\ncontribute significantly to the torque. This regime is discussed in the context\nof asymptotic isometry for very thin plates submitted to vanishing tension but\nlarge change of shape, as in crumpling.",
        "positive": "Meta-stable nematic pre-ordering in smectic liquid crystalline phase\n  transitions: Modeling and simulation studies using a high-order Landau-de Gennes type\nmodel for the direct isotropic/smectic-A liquid crystal transition are\npresented showing the existence of meta-stable nematic pre-ordering under\ncertain conditions, in agreement with experimental observations (Tokita, M. et\nal. Macromolecules 2006, 39, 2021-2023)"
    },
    {
        "anchor": "Mode-coupling theory for the steady-state dynamics of active Brownian\n  particles: We present a theory for the steady-state dynamics of a two-dimensional system\nof spherically symmetric active Brownian particles. The derivation of the\ntheory consists of two steps. First, we integrate out the self-propulsions and\nobtain a many-particle evolution equation for the probability distribution of\nthe particles' positions. Second, we use projection operator technique and a\nmode-coupling-like factorization approximation to derive an equation of motion\nfor the density correlation function. The nonequilibrium character of the\nactive system manifests itself through the presence of a steady-state\ncorrelation function that quantifies spatial correlations of microscopic\nsteady-state currents of the particles. This function determines the dependence\nof the short-time dynamics on the activity. It also enters into the expression\nfor the memory matrix and thus influences the long-time glassy dynamics.",
        "positive": "Shear thickening in granular suspensions: inter-particle friction and\n  dynamically correlated clusters: We consider the shear rheology of concentrated suspensions of non-Brownian\nfrictional particles. The key result of our study is the emergence of a\npronounced shear-thickening regime, where frictionless particles would normally\nundergo shear-thinning. We clarify that shear thickening in our simulations is\ndue to enhanced energy dissipation via frictional inter-particle forces.\nMoreover, we evidence the formation of dynamically correlated particle-clusters\nof size $\\xi$, which contribute to shear thickening via an increase in\n\\emph{viscous} dissipation. A scaling argument gives $\\eta\\sim \\xi^2$, which is\nin very good agreement with the data."
    },
    {
        "anchor": "Reply to Comment on \"Circular Motion of Asymmetric Self-Propelling\n  Particles\": In a Comment [Phys. Rev. Lett. 113, 029801 (2014)] on our Letter on\nself-propelled asymmetric particles [Phys. Rev. Lett. 110, 198302 (2013);\narXiv:1302.5787], Felderhof claims that our theory based on Langevin equations\nwould be conceptually wrong. In this Reply we show that our theory is\nappropriate, consistent, and physically justified.",
        "positive": "Anomalous energetics and dynamics of moving vortices: Motivated by the general problem of moving topological defects in an\notherwise ordered state and specifically, by the anomalous dynamics observed in\nvortex-antivortex annihilation and coarsening experiments in freely-suspended\nsmectic-C films by Clark, et al., I study the deformation, energetics and\ndynamics of moving vortices in an overdamped xy-model and show that their\nproperties are significantly and qualitatively modified by the motion."
    },
    {
        "anchor": "Translocation of an Active Polymer into a Circular Cavity: Translocation dynamics of an active semi-flexible polymer through a nano-pore\ninto a rigid two dimensional circular cavity, and the polymer packing dynamics\nhave been studied by using Langevin dynamics (LD) simulations. The results show\nthat the force exponent $\\beta$, for regime of small cavity radius, i.e. $R \\ll\nR_{\\textrm{g}}$, where $R_{\\textrm{g}}$ is the gyration radius of the passive\nsemi-flexible polymer in two dimensional free space, is $\\beta=-1$, while for\nlarge values of $R \\gg R_{\\textrm{g}}$ the asymptotic value of the force\nexponent is $\\beta \\approx -0.92$. The force exponent is defined by the scaling\nform of the average translocation time $\\langle \\tau \\rangle \\propto\nF_{\\textrm{sp}}^{\\beta}$, where $F_{\\textrm{sp}}$ is the self-propelling force.\nMoreover, using the definition of the turning number for the polymer inside the\ncavity, it has been found that at the end of translocation process for small\nvalue of $R$ and in the strong force limit the polymer configuration is more\nregular than the case in which the value of $R$ is large or the force is weak.",
        "positive": "A ribbon model for nematic polymer networks: We present a theory of deformation of ribbons made of nematic polymer\nnetworks (NPNs). These materials exhibit properties of rubber and nematic\nliquid crystals, and can be activated by external stimuli of heat and light. A\ntwo-dimensional energy for a sheet of such a material has already been derived\nfrom the celebrated neo-classical energy of nematic elastomers in three space\ndimensions. Here, we use a dimension reduction method to obtain the appropriate\nenergy for a ribbon from the aforementioned sheet energy. We also present an\nillustrative example of a rectangular NPN ribbon that undergoes in-plane\nserpentine deformations upon activation under an appropriate set of boundary\nconditions."
    },
    {
        "anchor": "Stability of discoidal high-density lipoprotein particles: Motivated by experimental and numerical studies revealing that discoidal\nhigh-density lipoprotein (HDL) particles may adopt flat elliptical and\nnonplanar saddle-like configurations, it is hypothesized that these might\nrepresent stabilized configurations of initially unstable flat circular\nparticles. A variational description is developed to explore the stability of a\nflat circular discoidal HDL particle. While the lipid bilayer is modeled as\ntwo-dimensional fluid film endowed with surface tension and bending elasticity,\nthe apoA-I belt is modeled as one-dimensional inextensible twist-free chain\nendowed with bending elasticity. Stability is investigated using the second\nvariation of the underlying energy functional. Various planar and nonplanar\ninstability modes are predicted and corresponding nondimensional critical\nvalues of salient dimensionless parameters are obtained. The results predict\nthat the first planar and nonplanar unstable modes occur due to in-plane\nelliptical and transverse saddle-like perturbations. Based on available data,\ndetailed stability diagrams indicate the range of input parameters for which a\nflat circular discoidal HDL particle is linearly stable or unstable.",
        "positive": "Microscopic Density Functional Theory for Dendrimers: Density functional theory for a simple model of dendrimers is proposed. The\ntheory is based on fundamental measure theory which accounts for the\nhard-sphere repulsion of the segments and on the Wertheim first-order\nperturbation theory for the correlations due to connectivity. Set of the\nrecurrence formulae for the ideal chain contribution involving simple integrals\nis derived. By using perturbation theory dispersion forces can be easily\nincluded."
    },
    {
        "anchor": "Stress percolation criticality of glass to fluid transition in active\n  cell layers: Using three-dimensional representation of confluent cell layers, we map the\namorphous solid to fluid phase transition in active cell layers onto the\ntwo-dimensional (2D) site percolation universality class. Importantly, we unify\ntwo distinct, predominant, pathways associated with this transition; namely (i)\ncell-cell adhesion and (ii) active traction forces. For each pathway, we\nindependently vary the corresponding control parameter and focus on the\nemergent mechanical stress patterns as the monolayer transitions from a glassy-\nto a fluid-like state. Through finite-size scaling analyses, our results lead\nus to establish the glassy- to fluid-like transition as a critical phenomena in\nterms of stress development in the cell layer and show that the associated\ncriticality belongs to the 2D site percolation universality class. Our findings\noffer a fresh perspective on solid (glass-like) to fluid phase transition in\nactive cell layers and can bridge our understanding of glassy behaviors in\nactive matter with potential implications in biological processes such as wound\nhealing, development, and cancer progression.",
        "positive": "Dynamical collective memory in fluidized granular materials: Recent experiments with rotational diffusion of a probe in a vibrated\ngranular media revealed a rich scenario, ranging from the dilute gas to the\ndense liquid with cage effects and an unexpected superdiffusive behavior at\nlarge times. Here we setup a simulation that reproduces quantitatively the\nexperimental observations and allows us to investigate the properties of the\nhost granular medium, a task not feasible in the experiment. We discover a\npersistent collective rotational mode which emerges at high density and low\ngranular temperature: a macroscopic fraction of the medium slowly rotates,\nrandomly switching direction after very long times. Such a rotational mode of\nthe host medium is the origin of probe's superdiffusion. Collective motion is\naccompanied by a kind of dynamical heterogeneity at intermediate times (in the\ncage stage) followed by a strong reduction of fluctuations at late times, when\nsuperdiffusion sets in."
    },
    {
        "anchor": "Mesoscale Organization and Dynamics in Binary Ionic Liquid Mixtures: The impact of mesoscale organization on dynamics and ion transport in binary\nionic liquid mixtures is investigated by broadband dielectric spectroscopy,\ndynamic-mechanical spectroscopy, x-ray scattering, and molecular dynamics\nsimulations. The mixtures are found to form distinct liquids with macroscopic\nproperties that significantly deviate from weighted contributions of the neat\ncomponents. For instance, it is shown that the mesoscale morphologies in ionic\nliquids can be tuned by mixing to enhance the static dielectric permittivity of\nthe resulting liquid by as high as 100$\\%$ relative to the neat ionic liquid\ncomponents. This enhancement is attributed to the intricate role of interfacial\ndynamics associated with the changes in the mesoscopic aggregate morphologies\nin these systems. These results demonstrate the potential to design the\nphysicochemical properties of ionic liquids through control of solvophobic\naggregation",
        "positive": "Joint effect of advection, diffusion, and capillary attraction on the\n  spatial structure of particle depositions from evaporating droplets: A simplified model is developed, which allows us to perform computer\nsimulations of the particles transport in an evaporating droplet with a contact\nline pinned to a hydrophilic substrate. The model accounts for advection in the\ndroplet, diffusion and particle attraction by capillary forces. On the basis of\nthe simulations, we analyze the physical mechanisms of forming of individual\nchains of particles inside the annular sediment. The parameters chosen\ncorrespond to the experiments of Park and Moon [Langmuir 22, 3506 (2006)],\nwhere an annular deposition and snakelike chains of colloid particles have been\nidentified. The annular sediment is formed by advection and diffusion\ntransport. We find that the close packing of the particles in the sediment is\npossible if the evaporation time exceeds the characteristic time of\ndiffusion-based ordering. We show that the chains are formed by the end of the\nevaporation process due to capillary attraction of particles in the region\nbounded by a fixing radius, where the local droplet height is comparable to the\nparticle size. At the beginning of the evaporation, the annular deposition is\nshown to expand faster than the fixing radius moves. However, by the end of the\nprocess, the fixing radius rapidly outreaches the expanding inner front of the\nring. The snakelike chains are formed at this final stage when the fixing\nradius moves toward the symmetry axis."
    },
    {
        "anchor": "Importance of Varying Permittivity on the Conductivity of\n  Polyelectrolyte Solutions: Dissolved ions can alter the local permittivity of water, nevertheless most\ntheories and simulations ignore this fact. We present a novel algorithm for\ntreating spatial and temporal variations in the permittivity and use it to\nmeasure the equivalent conductivity of a salt-free polyelectrolyte solution.\nOur new approach quantitatively reproduces experimental results unlike\nsimulations with a constant permittivity that even qualitatively fail to\ndescribe the data. We can relate this success to a change in the ion\ndistribution close to the polymer due to the built-up of a permittivity\ngradient.",
        "positive": "Aggregation Dynamics of Rigid Polyelectrolytes: Similarly-charged polyelectrolytes are known to attract each other and\naggregate into bundles when the charge density of the polymers exceeds a\ncritical value that depends on the valency of the counterions. The dynamics of\naggregation of such rigid polyelectrolytes are studied using large scale\nmolecular dynamics simulations. We find that the morphology of the aggregates\ndepends on the value of the charge density of the polymers. For values close to\nthe critical value, the shape of the aggregates is cylindrical with height\nequal to the length of a single polyelectrolyte chain. However, for larger\nvalues of charge, the linear extent of the aggregates increases as more and\nmore polymers aggregate.In both the cases, we show that the number of\naggregates decrease with time as power laws with exponents that are not\nnumerically distinguishable from each other, and are independent of charge\ndensity of the polymers, valency of the counterions, density, and length of the\npolyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski\ncoagulation equation with kernels determined from the molecular dynamics\nsimulations, and justify the numerically obtained value of the exponent. Our\nresults suggest that, once counterions condense, effective interactions between\npolyelectrolyte chains short-ranged and the aggregation of polyelectrolytes is\ndiffusion-limited."
    },
    {
        "anchor": "Fluctuation effects in the theory of microphase separation of diblock\n  copolymers in the presence of an electric field: We generalize the Fredrickson-Helfand theory of the microphase separation in\nsymmetric diblock copolymer melts by taking into account the influence of a\ntime-independent homogeneous electric field on the composition fluctuations\nwithin the self-consistent Hartree approximation. We predict that electric\nfields suppress composition fluctuations, and consequently weaken the\nfirst-order transition. In the presence of an electric field the critical\ntemperature of the order-disorder transition is shifted towards its mean-field\nvalue. The collective structure factor in the disordered phase becomes\nanisotropic in the presence of the electric field. Fluctuational modulations of\nthe order parameter along the field direction are strongest suppressed. The\nlatter is in accordance with the parallel orientation of the lamellae in the\nordered state.",
        "positive": "The role of sample height in the stacking diagram of colloidal mixtures\n  under gravity: Bulk phase separation is responsible for the occurrence of stacks of\ndifferent layers in sedimentation of colloidal mixtures. A recently proposed\ntheory (de las Heras and Schmidt 2013 Soft Matter 9 8636) establishes a unique\nconnection between the bulk phase behaviour and\nsedimentation-diffusion-equilibrium. The theory constructs a stacking diagram\nof all possible sequences of stacks under gravity in the limit of very high\n(infinite) sample heights. Here, we study the stacking diagrams of colloidal\nmixtures at finite sample height, h. We demonstrate that h plays a vital role\nin sedimentation-diffusion-equilibrium of colloidal mixtures. The region of the\nstacking diagram occupied by a given sequence of stacks depends on h. Hence,\ntwo samples with different heights but identical colloidal concentrations can\ndevelop different stacking sequences. In addition, the stacking diagrams for\ndifferent heights can be qualitatively different since some stacking sequences\noccur only in a given interval of sample heights. We use the theory to\ninvestigate the stacking diagrams of both model bulk systems and mixtures of\npatchy particles that differ either by the number or by the types of patches."
    },
    {
        "anchor": "Monte-Carlo simulations of star-branched polyelectrolyte micelles: The concentration profiles of monomers and counterions in star-branched\npolyelectrolyte micelles are calculated through Monte-Carlo simulations, using\nthe simplest freely-jointed chain model. We have investigated the onset of\ndifferent regimes corresponding to the spherical and Manning condensation of\ncounterions as a function of the strength of the Coulomb coupling. The\nMonte-Carlo results are in fair agreement with the predictions of\nSelf-Consistent-Field analytical models. We have simulated a real system of\ndiblock copolymer micelles of (sodium-polystyrene-sulfonate)(NaPSS)--\n(polyethylene-- propylene)(PEP) with f=54 hydrophilic branches of N=251\nmonomers at room temperature in salt-free solution and compared the calculated\nform factor with our neutron-scattering data.",
        "positive": "Incremental response of granular materials: DEM results: We systematically investigate the incremental response of various equilibrium\nstates of dense 2D model granular materials, along the biaxial compression path\n(\\sigma 11 < \\sigma 22, \\sigma 12 = 0). Stress increments are applied in\narbitrary directions in 3- dimensional stress space (\\sigma 11, \\sigma 22,\n\\sigma 12). In states with stable contact networks we compute the stiffness\nmatrix and the elastic moduli, and separate elastic and irreversible strains in\nthe range in which the latter are homogeneous functions of degree one of stress\nincrements. Without principal stress axis rotation, the response abides by\nelastoplasticity with a Mohr-Coulomb criterion and a non-associated flow rule.\nHowever a nonelastic shear strain is also observed for increments of \\sigma 12,\nand shear and in-plane responses couple. This behavior correlates to the\ndistribution of friction mobilization and sliding at contacts."
    },
    {
        "anchor": "Transport and bistable kinetics of a Brownian particle in a\n  nonequilibrium environment: A system reservoir model, where the associated reservoir is modulated by an\nexternal colored random force, is proposed to study the transport of an\noverdamped Brownian particle in a periodic potential. We then derive the\nanalytical expression for the average velocity, mobility, and diffusion rate.\nThe bistable kinetics and escape rate from a metastable state in the overdamped\nregion are studied consequently. By numerical simulation we then demonstrate\nthat our analytical escape rate is in good agreement with that of numerical\nresult.",
        "positive": "Acoustic emission associated with the bursting of a gas bubble at the\n  free surface of a non-newtonian fluid: We report experimental measurements of the acoustic emission associated with\nthe bursting of a gas bubble at the free surface of a non-newtonian fluid. On\naccount of the viscoelastic properties of the fluid, the bubble is generally\nelongated. The associated frequency and duration of the acoustic signal are\ndiscussed with regard to the shape of the bubble and successfully accounted for\nby a simple linear model. The acoustic energy exhibits a high sensitivity to\nthe dynamics of the thin film bursting, which demonstrates that, in practice,\nit is barely possible to deduce from the acoustic measurements the total amount\nof energy released by the event. Our experimental findings provide clues for\nthe understanding of the signals from either volcanoes or foams, where one\nobserves respectively, the bursting of giant bubbles at the free surface of\nlava and bubble bursting avalanches."
    },
    {
        "anchor": "A nematic liquid crystal with an immersed body: equilibrium, stress, and\n  paradox: We examine the equilibrium configurations of a nematic liquid crystal with an\nimmersed body in two-dimensions. A complex variables formulation provides a\nmeans for finding analytical solutions in the case of strong anchoring. Local\ntractions, forces, and torques on the body are discussed in a general setting.\nFor weak (finite) anchoring strengths, an effective boundary technique is\nproposed which is used to determine asymptotic solutions. The energy-minimizing\nlocations of topological defects on the body surface are also discussed. A\nnumber of examples are provided, including circular and triangular bodies, and\na Janus particle with hybrid anchoring conditions. Analogues to classical\nresults in fluid dynamics are identified, including d'Alembert's paradox,\nStokes' paradox, and the Kutta condition for circulation selection.",
        "positive": "Surface effects in nucleation and growth of smectic B crystals in thin\n  samples: We present an experimental study of the surface effects (interactions with\nthe container walls) during the nucleation and growth of smectic B crystals\nfrom the nematic in free growth and directional solidification of a mesogenic\nmolecule ($C_4H_9-(C_6H_{10})_2CN$) called CCH4 in thin (of thickness in the 10\n$\\mu$m range) samples. We follow the dynamics of the system in real time with a\npolarizing microscope. The inner surfaces of the glass-plate samples are coated\nwith polymeric films, either rubbed polyimid (PI) films or monooriented\npoly(tetrafluoroethylene) (PTFE) films deposited by friction at high\ntemperature. The orientation of the nematic and the smectic B is planar. In\nPI-coated samples, the orientation effect of SmB crystals is mediated by the\nnematic, whereas, in PTFE-coated samples, it results from a homoepitaxy\nphenomenon occurring for two degenerate orientations. A recrystallization\nphenomenon partly destroys the initial distribution of crystal orientations. In\ndirectional solidification of polycrystals in PTFE-coated samples, a particular\ndynamics of faceted grain boundary grooves is at the origin of a dynamical\nmechanism of grain selection. Surface effects also are responsible for the\nnucleation of misoriented terraces on facets and the generation of lattice\ndefects in the solid."
    },
    {
        "anchor": "On the improvement of SPT2 approach in the theory of a hard sphere fluid\n  in disordered porous media: The SPT2 approach is based on the scaled particle theory and developed for\nthe description of thermodynamic properties of hard sphere (HS) fluids in\ndisordered porous media. Using this approach a porous medium is modelled as a\nquenched matrix of hard spheres (HS) or overlapping hard spheres (OHS). A hard\nsphere fluid immersed in a matrix can move in a void between matrix particles.\nA number of approximations were previously proposed within the SPT2 approach.\nAmong these approximations, the SPT2b1 has been considered as the most\nsuccessful and accurate one in a large range of fluid densities and for\ndifferent matrix parameters. However, at high densities, it can lack accuracy,\nsince it does not take into account that the maximum packing fraction of a HS\nfluid in a matrix is limited, not by the geometrical porosity of a matrix\n$\\phi_{0}$ and the probe particle porosity $\\phi$, but by another type of\nporosity $\\phi^{*}$ introduced in our previous studies. The porosity $\\phi^{*}$\nis related to the maximal adsorption capacity of a matrix and it is lower than\n$\\phi_{0}$ and larger than $\\phi$. This can be crucial for a fluid in matrices\nof low porosities and at high fluid density, especially in the region near\nclose-packing conditions. Therefore, the approximations SPT2b2 and SPT2b3\ntaking into account this feature were suggested, although they still needed a\ncorrection because of their poor accuracy. In the present study, we improved\nthe versions of these approximations, named as SPT2b2$^*$ and SPT2b3$^*$. We\ncompare these different approximations with the results of computer simulations\nperformed in the Monte Carlo grand-canonical ensemble. We test the SPT2\napproach both for the one- and three-dimensional cases. We show that the\nSPT2b3$^*$ provides a very good description of the chemical potential of a\nconfined fluid, which is better than others.",
        "positive": "Interface geometry of binary mixtures on curved substrates: Motivated by recent experimental work on multicomponent lipid membranes\nsupported by colloidal scaffolds, we report an exhaustive theoretical\ninvestigation of the equilibrium configurations of binary mixtures on curved\nsubstrates. Starting from the J\\\"ulicher-Lipowsky generalization of the\nCanham-Helfrich free energy to multicomponent membranes, we derive a number of\nexact relations governing the structure of an interface separating two lipid\nphases on arbitrarily shaped substrates and its stability. We then restrict our\nanalysis to four classes of surfaces of both applied and conceptual interest:\nthe sphere, axisymmetric surfaces, minimal surfaces and developable surfaces.\nFor each class we investigate how the structure of the geometry and topology of\nthe interface is affected by the shape of the substrate and we make various\ntestable predictions. Our work sheds light on the subtle interaction mechanism\nbetween membrane shape and its chemical composition and provides a solid\nframework for interpreting results from experiments on supported lipid\nbilayers."
    },
    {
        "anchor": "Optomechanics of liquid crystals for dynamical optical response of\n  photonic structures: We show that the mechanical effect of light on the orientational ordering of\nthe crystalline axis of a mesophase can be used to control the dynamics of the\noptical response of liquid crystal infiltrated photonic structures. The\ndemonstration is made using a one-dimensional periodic structure whose\nperiodicity is broken by the presence of a nematic liquid crystal defect layer.\nIn this study we report on output light polarization and/or intensity dynamics\nthat depends on the initial molecular ordering and incident light wavelength\nand intensity.",
        "positive": "Topological Defects and Defects-free states in toroidal nematics: We investigated the nematic ordering on a torus by means of analytic method\nand the method of simulated annealing, the Frank free energy, both in the\nstandard form and covariant form, were used in the study. The defect free state\nwas found to be the ground state in both cases. However, in the case of the\nstandard model, there are two kinds of defective free ordering and a transition\nbetween the two occurs at a critical value of radius ratio $k=\\frac{r}{R}$. The\nfirst one is $\\theta=0$ in the small $k$ regime and the second one is a\nvariable $\\theta$ with position of the torus. In the case of the covariant\nmodel the ground state is confirmed to be the infinitely degenerate of $\\theta$\nequals to a random constant. The states with defects are the excited states,\nwhere the pairs of defects excited and, duo to the barrier between positive and\nnegative defects, have pretty long life. The behavior of the defect state\nbasically the same for both of the two models."
    },
    {
        "anchor": "Induced phase transformation in ionizable colloidal nanoparticles: Acid-base equilibria directly influence the functionality and behavior of\nparticles in a system. Due to the ionizing effects of acid-base functional\ngroups, particles will undergo charge exchange. The degree of ionization and\ntheir intermolecular and electrostatic interactions are controlled by varying\nthe pH and salt concentration of the solution in a system. Although the pH can\nbe tuned in experiments, it is hard to model this effect using simulations or\ntheoretical approaches. This is due to the difficulty in treating charge\nregulation and capturing the cooperative effects in a colloidal suspension with\nCoulombic interaction. In this work, we analyze a suspension of ionizable\ncolloidal particles via Brownian simulations and derive a phase diagram of the\nsystem as a function of pH. It is observed that as pH increases, particles\nfunctionalized with acid groups change their arrangement from face-centered\ncubic (FCC) packing to a disordered state. We attribute these transitions to an\nincrease in the degree of charge polydispersity arising from an increase in pH.\nOur work shows that charge regulation leads to amorphous solids in colloids\nwhen the mean nanoparticle charge is sufficiently high.",
        "positive": "Rejuvenation and overaging in a colloidal glass under shear: We report the modifications of the microscopic dynamics of a colloidal glass\nsubmitted to shear. We use multispeckle diffusing wave spectroscopy to monitor\nthe evolution of the spontaneous slow relaxation processes after the sample\nhave been submitted to various straining. We show that high shear rejuvenates\nthe system and accelerates its dynamics whereas moderate shear overage the\nsystem. We analyze this phenomena within the frame of the Bouchaud's trap\nmodel."
    },
    {
        "anchor": "Active crystallization from power functional theory: We address the gas, liquid, and crystal phase behaviour of active Brownian\nparticles in three dimensions. The nonequilibrium force balance at coexistence\nleads to equality of state functions for which we use power functional\napproximations. Motility-induced phase separation starts at a critical point\nand quickly becomes metastable against active freezing for P\\'eclet numbers\nabove a nonequilibrium triple point. The mean swim speed acts as a state\nvariable, similar to the density of depletion agents in colloidal demixing. We\nobtain agreement with recent simulation results and correctly predict the\nstrength of particle number fluctuations in active fluids.",
        "positive": "Free energy calculations for atomic solids through the Einstein\n  crystal/molecule methodology using GROMACS and LAMMPS: In this work the free energy of solid phases is computed for the\nLennard-Jones potential and for a model of NaCl. The free energy is evaluated\nthrough the Einstein crystal/molecule methodologies using the Molecular\nDynamics programs: GROMACS and LAMMPS. The obtained results are compared with\nthe results obtained from Monte Carlo. Good agreement between the different\nprograms and methodologies was found. The procedure to perform the free energy\ncalculations for the solid phase in the Molecular Dynamic programs is\ndescribed. Since these programs allow to study any continuous intermolecular\npotential (when given in a tabulated form) this work shows that for isotropic\npotentials (describing for instance atomic solids or colloidal particles) free\nenergy calculations can be performed on a routinely basis using GROMACS and/or\nLAMMPS."
    },
    {
        "anchor": "Deformation of a biconcave-discoid capsule in extensional flow and\n  electric field: Biconcave-discoid (empirical shape of a red blood cell) capsule finds\nnumerous applications in the field of bio-fluid dynamics and rheology, apart\nfrom understanding the behavior of red blood cells (RBC) in blood flow. A\ndetailed analysis is, therefore, carried out to understand the effects of the\nuniaxial extensional flow and electric field on the deformation of a RBC and\nbiconcave-discoid polymeric capsule in the axisymmetric regime. The transient\ndeformation is computed numerically using axisymmetric boundary integral method\nfor Stokes flow considering the Skalak membrane constitutive law as the model\nfor the area incompressible RBC/biconcave-discoid capsule membrane. A\nremarkable biconcave-discoid to prolate spheroid transition is observed when\nthe elastic energy is overcome by the viscous or Maxwell electric stresses.\nMoreover, the significance of membrane stresses developed during the\ndeformation and at steady state and different modes of deformation are\npresented. This study should be useful in designing an artificial system\ninvolving biological cells under an electric field.",
        "positive": "Dynamic phase coexistence in glass-forming liquids: One of the most controversial hypotheses for explaining the heterogeneous\ndynamics of glasses postulates the temporary coexistence of two phases\ncharacterized by a high and by a low diffusivity. In this scenario, two phases\nwith different diffusivities coexist for a time of the order of the relaxation\ntime and mix afterwards. Unfortunately, it is difficult to measure the\nsingle-particle diffusivities to test this hypothesis. Indeed, although the\nnon-Gaussian shape of the van-Hove distribution suggests the transient\nexistence of a diffusivity distribution, it is not possible to infer from this\nquantity whether two or more dynamical phases coexist. Here we provide the\nfirst direct observation of the dynamical coexistence of two phases with\ndifferent diffusivities, by showing that in the deeply supercooled regime the\ndistribution of the single-particle diffusivities acquires a transient bimodal\nshape. We relate this distribution to the heterogeneity of the dynamics and to\nthe breakdown of the Stokes-Einstein relation, and we show that the coexistence\nof two dynamical phases occurs up to a timescale growing faster than the\nrelaxation time on cooling, for some of the considered models. Our work offers\na basis for rationalizing the dynamics of supercooled liquids and for relating\ntheir structural and dynamical properties."
    },
    {
        "anchor": "Dynamics of the molecular orientation field coupled to ions in\n  two-dimensional ferroelectric liquid crystals: Molecular orientation fluctuations in ferroelectric smectic liquid crystals\nproduce space charges, due to the divergence of the spontaneous polarization.\nThese space charges interact with mobile ions, so that one must consider the\ncoupled dynamics of the orientation and ionic degrees of freedom. Previous\ntheory and light scattering experiments on thin free-standing films of\nferroelectric liquid crystals have not included this coupling, possibly\ninvalidating their quantitative conclusions. We consider the most important\ncase of very slow ionic dynamics, compared to rapid orientational fluctuations,\nand focus on the use of a short electric field pulse to quench orientational\nfluctuations. We find that the resulting change in scattered light intensity\nmust include a term due to the quasistatic ionic configuration, which has\npreviously been ignored. In addition to developing the general theory, we\npresent a simple model to demonstrate the role of this added term.",
        "positive": "Drag of Two Cylindrical Intruders in a Two-Dimensional Granular\n  Environment: The drag of two cylindrical intruders in a two-dimensional granular\nenvironment is numerically studied by the discrete element method. We find the\nyield force, below which the intruders cannot move because of interactions with\nthe surrounding particles. Above the yield force, on the other hand, the\nintruders can move at a constant speed. We investigate the relationship between\nthe drag force and the steady speed of the intruders, where the speed becomes\nhigher as the distance between the intruders decreases. We confirm that the\norigin of the yield is the Coulombic friction between the particles and the\nbottom plate by changing the value of the friction coefficient. We also find\nthat the yield force is almost proportional to the friction coefficient, which\nmeans that the number of particles determining the yield force is almost\nconstant. On the other hand, the two-dimensional elasticity is applicable to\ndetermine the stress fields around the intruders. We confirm that fields\nasymmetric with respect to the drag direction are reproduced by using the\ninformation of the stresses on the surfaces of the intruders by introducing\nbipolar coordinates."
    },
    {
        "anchor": "Snap buckling of bistable beams under combined mechanical and magnetic\n  loading: We investigate the mechanics of bistable, hard-magnetic, elastic beams,\ncombining experiments, finite element modeling (FEM), and a reduced-order\ntheory. The beam is made of a hard magneto-rheological elastomer, comprising\ntwo segments with antiparallel magnetization along the centerline, and is set\ninto a bistable curved configuration by imposing an end-to-end shortening.\nReversible snapping is possible between these two stable states. First, we\nexperimentally characterize the critical field strength for the onset of\nsnapping, at different levels of end-to-end shortening. Second, we perform 3D\nFEM simulations using the Riks method to analyze high-order deformation modes\nduring snapping. Third, we develop a reduced-order centerline-based beam theory\nto rationalize the observed magneto-elastic response. The theory and\nsimulations are validated against experiments, with an excellent quantitative\nagreement. Finally, we consider the case of combined magnetic and\nmechanical-indentation loading, examining how the applied field affects the\nbistability and quantifying the maximum load-bearing capacity. Our work\nprovides a set of predictive tools for the rational design of one-dimensional,\nbistable, magneto-elastic structural elements.",
        "positive": "The effect of flexibility and bend angle on the phase diagram of hard\n  colloidal boomerangs: We study the effect of flexibility and bend angle on systems of hard\nsemiflexible boomerangs. These are modelled as two rodlike segments joined at\none end with an angle that can fluctuate about a preferred angle. We use a\nsecond-virial theory for semiflexible chains with two segments, and numerically\nsolve for the full orientation distribution function as a function of the four\nangles that determine the boomerang's orientation. We plot the single segment\ndistributions as a function of two angles as well as the interarm angle\ndistribution. For stiff boomerangs, we find prolate, oblate, and biaxial\nnematic phases depending on the bend angle and density, in partial agreement\nwith previous results on rigid boomerangs. For the case that the preferred\ninterarm angle is $90^\\circ$, however, we find that the biaxial nematic phase\nhas four-fold rather than two-fold rotational symmetry, and thus requires\nfourth-rank order parameters to describe it. In addition, we find that\nflexibility drastically reduces the region of stability for the biaxial nematic\nphase, with the prolate nematic becoming more favourable."
    },
    {
        "anchor": "Anomalous structure and dynamics of the Gaussian-core fluid: It is known that there are thermodynamic states for which the Gaussian-core\n(GC) fluid displays anomalous properties such as expansion upon isobaric\ncooling (density anomaly) and increased single-particle mobility upon\nisothermal compression (self-diffusivity anomaly). We investigate how\ntemperature and density affect its short-range translational structural order,\nas characterized by the two-body excess entropy. We find that there is a wide\nrange of conditions for which the short-range translational order of the GC\nfluid decreases upon isothermal compression (structural order anomaly). The\norigin of the structural anomaly is qualitatively similar to that of other\nanomalous fluids and is connected to how compression affects static\ncorrelations at different length scales. We find that the self-diffusivity of\nthe GC fluid obeys a scaling relationship with the two-body excess entropy that\nis very similar to the one observed for a variety of simple liquids. One\nconsequence of this relationship is that the state points for which structural,\nself-diffusivity, and density anomalies of the Gaussian-core fluid occur appear\nas cascading regions on the temperature-density plane, a phenomenon observed\nearlier for models of waterlike fluids. There are, however, key differences\nbetween the anomalies of GC and waterlike fluids, and we discuss how those can\nbe qualitatively understood by considering the respective interparticle\npotentials of these models. Finally, we note that the self-diffusivity of the\nGaussian-core fluid obeys different scaling laws depending on whether the\ntwo-body or total excess entropy is considered. This finding, which deserves\nmore comprehensive future study, appears to underscore the significance of\nhigher-body correlations for the behavior of fluids with bounded interactions.",
        "positive": "Temperature dependence of elastocaloric effect in natural rubber: The temperature dependence of the elastocaloric (eC) effect in natural rubber\n(NR) is studied adiabatically and isothermally. A broad temperature span for eC\neffect from 0 oC to 49 oC is observed. The maximum adiabatic temperature change\n({\\Delta}T) is 12 K at strain of 6 and occurs at 10 oC. These behaviors can be\npredicted by the temperature dependence of strain-induced crystallization (SIC)\nand temperature-induced crystallization (TIC). In isothermal condition, the\ndeduced {\\Delta}T from Clausius-Clapeyron factor can agree with the direct\nmeasurement at different temperatures. The eC performance of NR is compared\nwith shape memory alloys (SMAs). The potential of NR for a near room\ntemperature cooing application is primarily proved. This will open the SIC\nresearch of NR towards eC cooling direction."
    },
    {
        "anchor": "Soft Matrix: Extracting Inherent Length Scales in Sheared Amorphous\n  Solids: Amorphous solids yield upon crossing a strain threshold, after an initial\nelastic response, when subjected to mechanical deformation. The yielding\nprocess is characterized by local plastic events leading to non-affine\ndisplacements, and their interactions. Despite the lack of long-range\nstructural order, these disordered materials exhibit long-range spatial\ncorrelations in the non-affine displacement fields, which stems from the\nunderlying elasticity. Measuring a correlation length scale in deformed\namorphous solids, during the plastic process, is a non-trivial challenge, often\nrequiring an ad-hoc definition of localized regions. In this paper, we\nintroduce a novel computational approach called the \"soft matrix\" that enables\nsystematic analysis of mechanical response of local regions within a disordered\nsolid. In this method, we subject the amorphous solid to a quasistatic shear\nand allow a local region of interest to relax freely while allowing for elastic\nrelaxation of the background. The dependence of the yield strain upon the size\nof the probe region naturally reveals the existence of an intrinsic length\nscale ($\\zeta$) that governs the elasto-plastic properties, as observed in four\ndistinct model amorphous solids. This finding demonstrates the universality of\nthis characteristic length scale across a wide range of materials. We\ninvestigate the dependence of this length scale on the material's preparation\nhistory and find that $\\zeta$ increases with better annealing. Furthermore, the\nlocal mechanical properties measured within this framework provide more\naccurate estimates compared to existing techniques. Our study paves the way for\na comprehensive understanding of amorphous solids and facilitates improved\ncharacterization and design of these materials.",
        "positive": "Molecular Dynamics Simulation of Smaller Granular Particles Deposition\n  on a Larger One Due to Velocity Sequence Dependent Electrical Charge\n  Distribution: Deposition of smaller granular particles on a larger nucleus particle has\nbeen simulated in two-dimension using molecular dynamics method. Variation of\nsequences of velocity of deposited particles is conducted and reported in this\nwork. The sequences obey a normal distribution function of velocity with the\nsame parameters. It has been observed that for velocity in range of 0 to 0.02\nthe densest deposited site (15-17 % number of grains) is located at about angle\n{\\pi}/4 where location of injection point is {\\pi}/4. And the less dense is\nabout {\\pi}/4 + {\\pi}/2. Different sequences give similar result."
    },
    {
        "anchor": "Propagating front in an excited granular layer: A partial monolayer of ~ 20000 uniform spherical steel beads, vibrated\nvertically on a flat plate, shows remarkable ordering transitions and\ncooperative behavior just below 1g maximum acceleration. We study the stability\nof a quiescent disordered or ``amorphous'' state formed when the acceleration\nis switched off in the excited ``gaseous'' state. The transition from the\namorphous state back to the gaseous state upon increasing the plate's\nacceleration is generally subcritical: An external perturbation applied to one\nbead initiates a propagating front that produces a rapid transition. We measure\nthe front velocity as a function of the applied acceleration. This phenomenon\nis explained by a model based on a single vibrated particle with multiple\nattractors that is perturbed by collisions. A simulation shows that a\nsufficiently high rate of interparticle collisions can prevent trapping in the\nattractor corresponding to the nonmoving ground state.",
        "positive": "A hybrid bio-organic interface for neuronal photo-activation: Interfacing artificial functional materials and living neuronal tissues is at\nthe forefront of bio-nano-technology. Attempts have been so far based onto\nmicroscale processing of metals and inorganic semiconductors as electrodes or\nphotoactive layers in biased devices. More recently, also nanomaterials\nproperties have been investigated. In spite of extensive research however, the\ncommunication between biological tissues and artificial sensors is still a\nchallenge. Constraints consist in the complexity of the fabrication processes\n(i.e. metal and semiconductor lithography), the mechanical properties (e.g.\nflexibility and mechanical invasiveness) and chemical influence (e.g.\ninflammatory reactions). In addition, electrodes have fixed geometries that\nlimit the location in space of the stimulus and often electrical currents are\ndetrimental for the overall system. To this respect organic soft matter offers\na chance in terms of biological affinity and mechanical properties. In\nparticular conjugated polymers have appealing optoelectronic features which\ncould lead to a new generation of neuronal communication and photo-manipulation\ntechniques. So far conjugated polymers have being only tested as coatings of\nelectrodes for neuronal activity recording. Here we report an up-scale of their\nuse: the successful interfacing of an organic semiconductor to a network of\ncultured primary neurons, through optical excitation. This allows to a new\nparadigm for the optical stimulation of neurons which could have important\nimplications for the development of an artificial retina based on organic\nphotodetectors."
    },
    {
        "anchor": "A mechanically-derived contact model for adhesive elastic-perfectly\n  plastic particles. Part I: Utilizing the method of dimensionality reduction: In this two part series, we present a contact model able to capture the\nresponse of interacting adhesive elastic-perfectly plastic particles under a\nvariety of loadings. In Part I, we focus on elastic through fully-plastic\ncontact with and without adhesion. For these contact regimes the model is built\nupon the method of dimensionality reduction which allows the problem of a 3D\naxisymmetric contact to be mapped to a semi-equivalent problem of a 1D rigid\nindenter penetrating a bed of independent Hookean springs. Plasticity is\naccounted for by continuously varying the 1D indenter profile subject to a\nconstraint on the contact pressure. Unloading falls out naturally, and simply\nrequires lifting the 1D indenter out of the springs and tracking the force. By\naccounting for the incompressible nature of this plastic deformation, the\ncontact model is able to capture multi-neighbor dependent effects such as\nincreased force and formation of new contacts. JKR type adhesion is recovered\nseamlessly within the method of dimensionality reduction by simply allowing the\nsprings to stick to the 1D indenter's surface. Because of the mechanics-focused\nformulation of the contact model, only a few physical inputs describing the\ninteracting particles are needed: particle radius, Young's modulus, Poisson\nratio, yield stress, and effective surface energy. The contact model is\nvalidated against finite element simulations and analytic theory, including\nHertz's contact law and the JKR theory of adhesion. These comparisons show that\nthe proposed contact model is able to accurately capture plastic displacement,\naverage contact pressure, contact area, and force as a function of displacement\nfor contacts as well as particle volume within the elastic to fully-plastic\nregimes.",
        "positive": "Strength and energy consumption of inherently anisotropic rocks at\n  failure: Using a discrete-element approach and a bonding interaction law, we model and\ntest crushable inherently anisotropic structures reminiscent of the layering\nfound in sedimentary and metamorphic rocks. By systematically modifying the\nlevel of inherent anisotropy, we characterize the evolution of the failure\nstrength of circular rock samples discretized using a modified Voronoi\ntesselation under diametral point loading at different orientations relative to\nthe sample's layers. We characterize the failure strength, which can\ndramatically increase as the loading becomes orthogonal to the rock layers. We\nalso describe the evolution of the macroscopic failure modes as a function of\nthe loading orientation and the energy consumption at fissuring. Our simulation\nstrategy let us conclude that the length of bonds between Voronoi cells\ncontrols the energy being consumed in fissuring the rock sample, although\nfailure modes and strength are considerably changing. We end up this work\nshowing that the microstructure is largely afected by the level of inherent\nanisotropy and loading orientation."
    },
    {
        "anchor": "The elixir phase of chain molecule: A phase of matter is a familiar notion for inanimate physical matter. The\nnature of a phase of matter transcends the microscopic material properties. For\nexample, materials in the liquid phase have certain common properties\nindependent of the chemistry of the constituents: liquids take the shape of the\ncontainer; they flow; and they can be poured -- alcohol, oil and water as well\nas a Lennard-Jones computer model exhibit similar behavior when poised in the\nliquid phase. Here we identify a hitherto unstudied `phase' of matter, the\nelixir phase, in a simple model of a polymeric chain whose backbone has the\ncorrect local cylindrical symmetry induced by the tangent to the chain. The\nelixir phase appears on breaking the cylindrical symmetry by adding side\nspheres along the negative normal direction, as in proteins. This phase,\nnestled between other phases, has multiple ground states made up of building\nblocks of helices and almost planar sheets akin to protein native folds. We\ndiscuss the similarities of this `phase' of a finite size system to the liquid\ncrystal and spin glass phases. Our findings are relevant for understanding\nproteins; the creation of novel bio-inspired nano-machines; and also may have\nimplications for life elsewhere in the cosmos.",
        "positive": "Colloidomers: freely-jointed polymers made of droplets: An important goal of self-assembly is to achieve a preprogrammed structure\nwith high fidelity. Here, we control the valence of DNA-functionalized\nemulsions to make linear and branched model polymers, or `colloidomers'. The\ndistribution of cluster sizes is consistent with a polymerization process in\nwhich the droplets achieve their prescribed valence. Conformational dynamics\nreveals that the chains are freely-jointed, such that the end-to-end length\nscales with the number of bonds $N$ as $N^{\\nu}$, where $\\nu\\approx3/4$, in\nagreement with the Flory theory in 2D. The chain diffusion coefficient $D$\napproximately scales as $D\\propto N^{-\\nu}$, as predicted by the Zimm model.\nUnlike molecular polymers, colloidomers can be repeatedly assembled and\ndisassembled under temperature cycling, allowing for reconfigurable, responsive\nmatter."
    },
    {
        "anchor": "Solvent Exchange in a Hele-Shaw Cell Universality of Surface Nanodroplet\n  Nucleation: Solvent exchange (also called solvent shifting or Ouzo effect) is a generally\nused bottom-up process to mass-produce nanoscale droplets. In this process, a\ngood solvent for some oil is displaced by a poor one, leading to oil\nnanodroplet nucleation and subsequent growth. Here we perform this process on a\nhydrophobic substrate so that sessile droplets so-called surface\nnanodroplets-develop, following the work of Zhang et al. [Zhang, X.; Lu, Z.;\nTan, H.; Bao, L.; He, Y.; Sun, C.; Lohse, D. Proc. Natl. Acad. Sci. U.S.A.\n2015, 122, 9253-9257]. In contrast to what was done in that paper, we chose a\nvery well-controlled Hele-Shaw geometry with negligible gravitational effects,\ninjecting the poor solvent in the center of the Hele-Shaw cell, and\ncharacterize the emerging nanodroplets as a function of radial distance and\nflow rates. We find that the mean droplet volume per area <Vol>_area strongly\ndepends on the local Peclet number Pe and follows a universal scaling law\n<Vol>_area~Pe^(3/4). Moreover, the probability distribution function of the\ndroplet volume strongly depends on the local Pe as well, regardless of the flow\nrates and radial distance, giving strong support to the theoretical model of\nthe solvent exchange process developed in Zhang et al.'s work.",
        "positive": "Relaxation Behavior by Time-Salt and Time-Temperature Superpositions of\n  Polyelectrolyte Complexes from Coacervate to Precipitate: Complexation between anionic and cationic polyelectrolytes results in\nsolid-like precipitates or liquid-like coacervate depending on the added salt\nin the aqueous medium. However, the boundary between these polymer-rich phases\nis quite broad and the associated changes in the polymer relaxation in the\ncomplexes across the transition regime are poorly understood. In this work, the\nrelaxation dynamics of complexes across this transition is probed over a wide\ntimescale by measuring viscoelastic spectra and zero-shear viscosities at\nvarying temperatures and salt concentrations for two different salt types. We\nfind that the complexes exhibit time-temperature superposition (TTS) at all\nsalt concentrations, while the range of overlapped-frequencies for\ntime-temperature-salt superposition (TTSS) strongly depends on the salt\nconcentration (Cs) and gradually shifts to higher frequencies as Cs is\ndecreased. The sticky-Rouse model describes the relaxation behavior at all Cs.\nHowever, collective relaxation of polyelectrolyte complexes gradually\napproaches a rubbery regime and eventually exhibits a gel-like response as Cs\nis decreased and limits the validity of TTSS."
    },
    {
        "anchor": "Long-range hydrodynamic response of particulate liquids and liquid-laden\n  solids: In viscous particulate liquids, such as suspensions and polymer solutions,\nthe large-distance steady-state flow due to a local disturbance is commonly\ndescribed in terms of hydrodynamic screening -- beyond a correlation length\n$\\xi$ the response drops from that of the pure solvent, characterized by its\nviscosity $\\eta_0$, to that of the macroscopic liquid with viscosity $\\eta$.\nFor cases where $\\eta>>\\eta_0$ we show, based on general conservation\narguments, that this screening picture, while being asymptotically correct,\nshould be refined in an essential way. The crossover between the microscopic\nand macroscopic behaviors occurs gradually over a wide range of distances,\n$\\xi<<r<<\\xi\\sqrt{eta/\\eta_0}$. In liquid-laden solids, such as colloidal\nglasses, gels and liquid-filled porous media, where $\\eta-->\\infty$, this\nintermediate behavior takes over the entire large-distance response. The\nintermediate flow field, arising from the effect of mass displacement rather\nthan momentum diffusion, has several unique characteristics: (i) It has a\ndipolar shape with a $1/r^3$ spatial decay, negative transverse components, and\nvanishing angular average. (ii) Its amplitude depends on the liquid properties\nthrough $\\eta_0$ and $\\xi$ alone; thus, in cases where $\\xi$ is fixed by\ngeometry (e.g., for particulate liquids tightly confined in solid matrices),\nthe large-distance response is independent of particle concentration. (iii) The\nintermediate field builds up non-diffusively, with a distance-independent\nrelaxation rate, making it dominant at large distances before steady state has\nbeen reached. We demonstrate these general properties in three model systems.",
        "positive": "A polyconvex transversely-isotropic invariant-based formulation for\n  electro-mechanics: stability, minimisers and computational implementation: The fabrication of evermore sophisticated miniaturised soft robotic\ncomponents made up of Electro-Active Polymers (EAPs) is constantly demanding\nparallel development from the in-silico simulation point of view. The\nincorporation of crystallographic anisotropic micro-architectures, within an\notherwise nearly uniform isotropic soft polymer matrix, has shown great\npotential in terms of advanced three-dimensional actuation (i.e. stretching,\nbending, twisting), especially at large strains, that is, beyond the onset of\ngeometrical pull-in instabilities. To accommodate for this in-silico response,\nthis paper presents a phenomenological invariant-based polyconvex transversely\nisotropic framework for the simulation of EAPs at large strains. This research\nexpands previous work developed by Gil and Ortigosa for isotropic EAPs with the\nhelp of the pioneering work by Schr\\\"{o}eder and Neff in the context of\npolyconvexity for materials endowed with crystallographic architectures in\nsingle physics mechanics. The paper also summarises key important results both\nin terms of the existence of minimisers and material stability. In addition, a\nseries of numerical examples is presented in order to demonstrate the effect\nthat the anisotropic orientation and the contrast of material properties, as\nwell as the level of deformation and electric field, have upon the response of\nthe EAP when subjected to large three-dimensional stretching, bending and\ntorsion, including the possible development of wrinkling."
    },
    {
        "anchor": "Enhanced Dip Coating on a Soft Substrate: A solid, withdrawn from a liquid bath, entrains a thin liquid film. This\nsimple process, first described by Landau, Levich and Derjaguin (LLD), is\ncommonly observed in everyday life. It also plays a central role in liquid\ncapture by animals, and is widely used for surface-coating purposes in\nindustry. Motivated by the emerging interest in the mechanics of very soft\nmaterials, and in particular the resulting elastocapillary coupling, we develop\na dip-coating model that accounts for the additional presence of a soft solid\nlayer atop the rigid plate. The elastic response of this soft layer is\ndescribed by a Winkler's foundation. Using a combination of numerical, scaling\nand asymptotic-matching methods, we find a new softness-dependent power-law\nregime for the thickness of entrained liquid at small capillary number, which\ncorresponds to a modified physics at play in the dynamic meniscus. The\ncrossover between this regime and the classical dip-coating one occurs when the\nsubstrate's deformation is comparable to the thickness of the entrained liquid\nfilm.",
        "positive": "Short DNA persistence length in a mesoscopic helical model: The flexibility of short DNA chains is investigated via computation of the\naverage correlation function between dimers which defines the persistence\nlength. Path integration techniques have been applied to confine the phase\nspace available to base pair fluctuations and derive the partition function.\nThe apparent persistence lengths of a set of short chains have been computed as\na function of the twist conformation both in the over-twisted and the untwisted\nregimes, whereby the equilibrium twist is selected by free energy minimization.\nThe obtained values are significantly lower than those generally attributed to\nkilo-base long DNA. This points to an intrinsic helix flexibility at short\nlength scales, arising from large fluctuational effects and local bending, in\nline with recent experimental indications. The interplay between helical\nuntwisting and persistence length has been discussed for a heterogeneous\nfragment by weighing the effects of the sequence specificities through the\nnon-linear stacking potential."
    },
    {
        "anchor": "Coarse-graining DNA: Symmetry, non-local elasticity and persistence\n  length: While the behavior of double stranded DNA at mesoscopic scales is fairly well\nunderstood, less is known about its relation to the rich mechanical properties\nin the base-pair scale, which is crucial, for instance, to understand\nDNA-protein interactions and the nucleosome diffusion mechanism. Here, by\nemploying the rigid base pair model, we connect its microscopic parameters to\nthe persistence length. Combined with all-atom molecular dynamic simulations,\nour scheme identifies relevant couplings between different degrees of freedom\nat each coarse-graining step. This allows us to clarify how the scale\ndependence of the elastic moduli is determined in a systematic way encompassing\nthe role of previously unnoticed off site couplings between deformations with\ndifferent parity.",
        "positive": "Pitch tuning induced by optical torque in heliconical cholesteric liquid\n  crystals: Heliconical cholesteric liquid crystals are expected to be more sensitive to\ntorque induced by light field since their structure allows both bend and twist\nin molecular orientations, differently from the conventional cholesterics in\nwhich only twist deformation is involved, requiring much higher fields. We\nreport here a demonstration of tuning the helical pitch in heliconical\ncholesterics induced by an optical torque. Experimental observations are in\nagreement with expectations of the classical theory extended to include the\neffect of the optical field. A dual control of the helical pitch is achieved\nincluding both the low-frequency electric field applied along the helix axis\nand the optical field orthogonal to it."
    },
    {
        "anchor": "Colloidal analogues of charged and uncharged polymer chains with tunable\n  stiffness: Herein, we describe new methods to produce colloidal particle chains of three\nstiffness regimes that can be observed on a single-particle level, that is, on\nthe level of the monomers that make up the chain; the chains can even be\nobserved in concentrated systems without using molecular tracers. These methods\nrely on the following: dipolar interactions induced by external electric fields\nin combination with long-range charge repulsion to assemble the particles into\nchains only, and a bonding step to ensure that the particles remain assembled\nas chains even after the external field is switched off. We can control the\nlength and the flexibility of the chains. Additionally, we demonstrate that our\nmethod is generally applicable by using it to prepare several other colloidal\npolymers, such as block-copolymer chains, which are formed by combining rigid\nand flexible chains, spherocylinders, which are formed by heating rigid chains,\nand both atactic and isotactic chains, which are formed from\nheterodimericparticle monomer units. We demonstrate that the flexibility of the\ncharged chains can be tuned from very rigid (rod-like) to semiflexible (as in\nthe simplified polymer model of beads on a string) by changing the ionic\nstrength. This method can, in principle, be used with any type of colloidal\nparticle. Moreover, our systems can be matched in terms of refractive index and\ndensity, so that bulk measurements in real space are possible.",
        "positive": "Geometric signatures of tissue surface tension in a three-dimensional\n  model of confluent tissue: In dense biological tissues, cell types performing different roles remain\nsegregated by maintaining sharp interfaces. To better understand the mechanisms\nfor such sharp compartmentalization, we study the effect of an imposed\nheterotypic tension at the interface between two distinct cell types in a fully\n3D model for confluent tissues. We find that cells rapidly sort and\nself-organize to generate a tissue-scale interface between cell types, and\ncells adjacent to this interface exhibit signature geometric features including\nnematic-like ordering, bimodal facet areas, and registration, or alignment, of\ncell centers on either side of the two-tissue interface. The magnitude of these\nfeatures scales directly with the magnitude of imposed tension, suggesting that\nbiologists can estimate the magnitude of tissue surface tension between two\ntissue types simply by segmenting a 3D tissue. To uncover the underlying\nphysical mechanisms driving these geometric features, we develop two minimal,\nordered models using two different underlying lattices that identify an\nenergetic competition between bulk cell shapes and tissue interface area. When\nthe interface area dominates, changes to neighbor topology are costly and occur\nless frequently, which generates the observed geometric features."
    },
    {
        "anchor": "Effect of bond lifetime on the dynamics of a short-range attractive\n  colloidal system: We perform molecular dynamics simulations of short-range attractive colloid\nparticles modeled by a narrow (3% of the hard sphere diameter) square well\npotential of unit depth. We compare the dynamics of systems with the same\nthermodynamics but different bond lifetimes, by adding to the square well\npotential a thin barrier at the edge of the attractive well. For permanent\nbonds, the relaxation time $\\tau$ diverges as the packing fraction $\\phi$\napproaches a threshold related to percolation, while for short-lived bonds, the\n$\\phi$-dependence of $\\tau$ is more typical of a glassy system. At intermediate\nbond lifetimes, the $\\phi$-dependence of $\\tau$ is driven by percolation at low\n$\\phi$, but then crosses over to glassy behavior at higher $\\phi$. We also\nstudy the wavevector dependence of the percolation dynamics.",
        "positive": "Modeling and simulation of coagulation according to DLVO-theory in a\n  continuum model for electrolyte solutions: This paper presents a model of coagulation in electrolyte solutions. In this\npaper, the coagulation process is modeled according to DLVO-theory, which is an\natomistic theory. On the other hand, we describe the dynamics in the\nelectrolyte solutions by the Poisson-Nernst-Planck system, which is a continuum\nmodel. The contribution of this paper is to include the atomistic description\nof coagulation based on DLVO-theory in the continuum Poisson-Nernst-Planck\nsystem. Thereby, we involve information from different spatial scales. For this\nreason, the presented model accounts for the short-range interactions and the\nlong-range interactions, which drive the coagulation process. Furthermore,\nmany-body effects are naturally included as the resulting model is a continuum\nmodel."
    },
    {
        "anchor": "Role of shape on the forces on an intruder moving through a dense\n  granular medium: We use numerical simulation to investigate the effect an intruder's shape has\non the drag and lift forces that it experiences while moving through a granular\nmedium composed of polydisperse disks of mean diameter d. The intruder\nvelocity,v, was varied from 0.1 \\sqrt(dg) to 20 \\sqrt(dg). For frictionless\nparticles (\\mu= 0.0)there is a gradual increase in drag force with increasing\nv, whereas for frictional systems (\\mu= 0.1,0.5) a constant drag regime appears\nat low velocities. The drag force depends weakly on the shape of the object\nprovided that the cross-section is same. The drag force depends linearly on the\nimmersion depth, while there is very little variation in lift force with depth\nfor certain shapes. The lift experienced by the object is a strong function of\nits shape at a given velocity. Shape has an effect on the distribution of\ncontacts around the surface of the intruder which may result in a strong lift\nfor certain shapes. We also show the force profiles around the intruder\nsurface.",
        "positive": "Coalescence of sessile aqueous droplets laden with surfactant: With most of the focus to date having been on the coalescence of freely\nsuspended droplets, much less is known about the coalescence of sessile\ndroplets, especially in the case of droplets laden with surfactant. Here, we\nemploy large-scale molecular dynamics simulations to investigate this\nphenomenon on substrates with different wettability. In particular, we unravel\nthe mass transport mechanism of surfactant during coalescence, thus explaining\nthe key mechanisms present in the process. Close similarities are found between\nthe coalescence of sessile droplets with equilibrium contact angles above\n90{\\deg} and that of freely suspended droplets, being practically the same when\nthe contact angle of the sessile droplets is above 140{\\deg}. Here, the initial\ncontact point is an area that creates an initial contact film of surfactant\nthat proceeds to break into engulfed aggregates. A major change in the physics\nappears below the 90{\\deg} contact angle, when the initial contact point\nbecomes small and line-like, strongly affecting many aspects of the process and\nallowing water to take part in the coalescence from the beginning. We find\ngrowth exponents consistent with a 2/3 power law on strongly wettable\nsubstrates but no evidence of linear growth. Overall bridge growth speed\nincreases with wettability for all surfactant concentrations, but the speeding\nup effect becomes weaker as surfactant concentration grows, along with a\ngeneral slowdown of the coalescence compared to pure water. Concurrently, the\nduration of the initial thermally limited regime increases strongly by almost\nan order of magnitude for strongly wettable substrates."
    },
    {
        "anchor": "Renormalization Group Limit Cycle for Three-Stranded DNA: We show that there exists an Efimov-like three strand DNA bound state at the\nduplex melting point and it is described by a renormalization group limit\ncycle. A nonperturbative RG is used to obtain this result in a model involving\nshort range pairing only. Our results suggest that Efimov physics can be tested\nin polymeric systems.",
        "positive": "DNA melting in poor solvent: The melting phase diagram of a double-stranded DNA in poor solvent is studied\nusing the pruned and enriched Rosenbluth method on a simple cubic lattice. As\nthe solvent quality is changed from good to poor, there is a non-monotonic\nchange in the melting temperature. First-order melting transition, as in good\nsolvent, gives way to continuous transition and then to further broadened\ntransitions where the order parameter smoothly becomes zero for sufficiently\npoor solvent. This change in the melting behavior is accompanied by a\ncontinuously varying critical exponent along the melting curve, hinting at a\nnon-universal nature of the melting transition. Further, we show that an\nunbound phase can be achieved just by changing the solvent quality.\nImportantly, our results conform to the experimental findings qualitatively."
    },
    {
        "anchor": "Domain and droplet sizes in emulsions stabilized by colloidal particles: Particle-stabilized emulsions are commonly used in various industrial\napplications. These emulsions can present in different forms, such as Pickering\nemulsions or bijels, which can be distinguished by their different topologies\nand rheology. We numerically investigate the effect of the volume fraction and\nthe uniform wettability of the stabilizing spherical particles in mixtures of\ntwo fluids. For this, we use the well-established three-dimensional lattice\nBoltzmann method, extended to allow for the added colloidal particles with\nnon-neutral wetting properties. We obtain data on the domain sizes in the\nemulsions by using both structure functions and the Hoshen-Kopelman (HK)\nalgorithm, and demonstrate that both methods have their own (dis-)advantages.\nWe confirm an inverse dependence between the concentration of particles and the\naverage radius of the stabilized droplets. Furthermore, we demonstrate the\neffect of particles detaching from interfaces on the emulsion properties and\ndomain size measurements.",
        "positive": "Comment on \"Edge-Induced Shear Banding in Entangled Polymeric Fluids\"\n  [arXiv: 1801.08798]: Based on numerical modeling with the diffusive Giesekus constitutive\nequation, a recent Letter [Phys. Rev. Lett. 120, 138002 (2018),\narXiv:1801.08798] claimed that the experimental reports of shear banding in\nentangled polymeric fluids were due to the disturbances from the sample edge.\nThe conclusion that true bulk shear banding is precluded in the presence of\nedge effects is at odds with many past experimental, theoretical, numerical,\nand computer simulation studies. We briefly discuss some problems of this work."
    },
    {
        "anchor": "Dynamics of colloidal particles in ice: We use X-ray Photon Correlation Spectroscopy (XPCS) to probe the dynamics of\ncolloidal particles in polycrystalline ice. During freezing, the dendritic ice\nmorphology and rejection of particles from the ice created regions of\nhigh-particle-density, where some of the colloids were forced into contact and\nformed disordered aggregates. We find that the particles in these high density\nregions underwent ballistic motion coupled with both stretched and compressed\nexponential decays of the intensity autocorrelation function, and that the\nparticles' characteristic velocity increased with temperature. We explain this\nbehavior in terms of ice grain boundary migration.",
        "positive": "Complex coacervation: A field theoretic simulation study of\n  polyelectrolyte complexation: Using the complex Langevin sampling strategy, field theoretic simulations are\nperformed to study the equilibrium phase behavior and structure of symmetric\npolycation-polyanion mixtures without salt in good solvents. Static structure\nfactors for the segment density and charge density are calculated and used to\nstudy the role of fluctuations in the electrostatic and chemical potential\nfields beyond the random phase approximation. We specifically focus on the role\nof charge density and molecular weight on the structure and complexation\nbehavior of polycation-polyanion solutions. A demixing phase transition to form\na ``complex coacervate'' is observed in strongly charged systems, and the\ncorresponding spinodal and binodal boundaries of the phase diagram are\ninvestigated."
    },
    {
        "anchor": "General Non-equilibrium Theory of Colloid Dynamics: A non-equilibrium extension of Onsager's canonical theory of thermal\nfluctuations is employed to derive a self-consistent theory for the description\nof the statistical properties of the instantaneous local concentration profile\nn(r,t) of a colloidal liquid in terms of the coupled time evolution equations\nof its mean value n(r,t) and of the covariance {\\sigma}(r,r';t) \\equiv\n<{\\delta}n(r,t){\\delta}n(r',t)> of its fluctuations {\\delta}n(r, t) = n(r, t) -\nn(r, t). These two coarse-grained equations involve a local mobility function\nb(r, t) which, in its turn, is written in terms of the memory function of the\ntwo-time correlation function C(r, r' ; t, t') \\equiv <{\\delta}n(r,\nt){\\delta}n(r',t')>. For given effective interactions between colloidal\nparticles and applied external fields, the resulting self-consistent theory is\naimed at describing the evolution of a strongly correlated colloidal liquid\nfrom an initial state with arbitrary mean and covariance n^0(r) and\n{\\sigma}^0(r,r') towards its equilibrium state characterized by the equilibrium\nlocal concentration profile n^(eq)(r) and equilibrium covariance\n{\\sigma}^(eq)(r,r').\n  This theory also provides a general theoretical framework to describe\nirreversible processes associated with dynamic arrest transitions, such as\naging, and the effects of spatial heterogeneities.",
        "positive": "Local size segregation in polydisperse hard sphere fluids: The structure of polydisperse hard sphere fluids, in the presence of a wall,\nis studied by the Rosenfeld density functional theory. Within this approach,\nthe local excess free energy depends on only four combinations of the full set\nof density fields. The case of continuous polydispersity thereby becomes\ntractable. We predict, generically, an oscillatory size segregation close to\nthe wall, and connect this, by a perturbation theory for narrow distributions,\nwith the reversible work for changing the size of one particle in a\nmonodisperse reference fluid."
    },
    {
        "anchor": "Collective motion of run-and-tumble particles drives aggregation in\n  one-dimensional systems: Active matter deals with systems whose particles consume energy at the\nindividual level in order to move. To unravel features such as the emergence of\ncollective structures several models have been suggested, such as the\non-lattice model of run-and-tumble particles implemented via the Persistent\nExclusion Process (PEP). In our work, we study a one dimensional system of\nrun-and-tumble repulsive or attractive particles, both on and off lattice.\nAdditionally, we implement a cluster motility dynamics in the on-lattice case\n(since in the off-lattice case cluster motility arises from the individual\nparticle dynamics). While we observe important differences between discrete and\ncontinuous dynamics, few common features are of particular importance.\nIncreasing particle density drives aggregation across all different systems\nexplored. For non-attractive particles, the effects of particle activity on\naggregation are largely independent of the details of the dynamics. On the\ncontrary, once attractive interactions are introduced, the steady state, which\nis completely determined by the interplay between these and the particles'\nactivity, becomes highly dependent on the details of the dynamics.",
        "positive": "Spontaneous spirals in vibrated granular chains: We present experimental measurements on the spontaneous formation of compact\nspiral structures in vertically-vibrated granular chains. Under weak vibration,\nwhen the chain is quasi two-dimensional and self-avoiding, spiral structures\nemerge from generic initial configurations. We compare geometrical\ncharacteristics of the spiral with that of an ideal tight spiral. Globally, the\nspiral undergoes a slow rotation such that to keep itself wound, while\ninternally, fast vibrational modes are excited along the backbone with\ntransverse oscillations dominating over longitudinal ones. Spirals have an\nextremely small volume in phase space, and hence, their formation demonstrates\nhow nonequilibrium dynamics can result in a nonuniform sampling of phase space."
    },
    {
        "anchor": "Random First Order Phase Transition Theory of the Structural Glass\n  Transition: We describe our perspective on the Structural Glass Transition (SGT) problem\nbuilt on the premise that a viable theory must provide a consistent picture of\nthe dynamics and statics, which are manifested by large increase in shear\nviscosity and thermodynamic anamolies respectively. For the static and dynamic\ndescription to be consistent we discovered, using a density functional\ndescription without explicit inclusion of quenched random interactions and a\nmean-field theory, that there be an exponentially large number of metastable\nstates at temperatures less than a critical transition temperature, $T_A$. At a\nlower temperature ($T_K < T_A$), which can be associated with the Kauzmann\ntemperature, the number of glassy states is non-extensive. Based on this theory\nwe formulated an entropic droplet picture to describe transport in finite\ndimensions in the temperature range $T_K < T < T_A$. From the finding that\nglasses are trapped in one of many metastable states below $T_A$ we argue that\nduring the SGT law of large numbers is violated. As a consequence in glasses\nthere are sub sample to sub sample fluctuations provided the system is observed\nfor times longer than the typical relaxation time in a liquid. These\nconsiderations, which find support in computer simulations and experiments,\nalso link the notion of dynamic heterogeneity to the violation of law of large\nnumbers. Thus, the finding that there is an extensive number of metastable\nstates in the range $T_K < T < T_A$ offers a coherent explanation of many of\nthe universal features of glass forming materials.",
        "positive": "Direct evidence of plastic events and dynamic heterogeneities in\n  soft-glasses: By using fluid-kinetic simulations of confined and concentrated emulsion\ndroplets, we investigate the nature of space non-homogeneity in soft-glassy\ndynamics and provide quantitative measurements of the statistical features of\nplastic events in the proximity of the yield-stress threshold. Above the yield\nstress, our results show the existence of a finite stress correlation scale,\nwhich can be mapped directly onto the {\\it cooperativity scale}, recently\nintroduced in the literature to capture non-local effects in the soft-glassy\ndynamics. In this regime, the emergence of a separate boundary (wall) rheology\nwith higher fluidity than the bulk, is highlighted in terms of near-wall\nspontaneous segregation of plastic events. Near the yield stress, where the\ncooperative scale cannot be estimated with sufficient accuracy, the system\nshows a clear increase of the stress correlation scale, whereas plastic events\nexhibit intermittent clustering in time, with no preferential spatial location.\nA quantitative measurement of the space-time correlation associated with the\nmotion of the interface of the droplets is key to spot the long-range amorphous\norder at the yield stress threshold."
    },
    {
        "anchor": "Coiling of an elastic beam inside a disk: A model for spider-capture\n  silk: Motivated by recent experimental observations of capillary-induced spooling\nof fibers inside droplets both in spider capture silk and in synthetic systems,\nwe investigate the behavior of a fiber packed in a drop. Using a simplified 2D\nmodel, we provide analytical predictions for the buckling threshold and the\ndeep post-buckling asymptotic behavior. The threshold for spooling is found to\nbe in particularly good agreement with experimental results. We further solve\nthe Elastica equations for a fiber confined in a soft potential, and track the\nequilibrium paths using numerical continuation techniques. A wealth of\ndifferent paths corresponding to different symmetries is uncovered, and their\nstability is finally discussed.",
        "positive": "Molecular Dynamics simulation of evaporation processes of fluid bridges\n  confined in slit-like pore: A simple fluid, described by point-like particles interacting via the\nLennard-Jones potential, is considered under confinement in a slit geometry\nbetween two walls at distance Lz apart for densities inside the vapor-liquid\ncoexistence curve. Equilibrium then requires the coexistence of a liquid\n\"bridge\" between the two walls, and vapor in the remaining pore volume. We\nstudy this equilibrium for several choices of the wall-fluid interaction\n(corresponding to the full range from complete wetting to complete drying, for\na macroscopically thick film), and consider also the kinetics of state changes\nin such a system. In particular, we study how this equilibrium is established\nby diffusion processes, when a liquid is inserted into an initially empty\ncapillary (partial or complete evaporation into vacuum), or when the volume\navailable for the vapor phase increases. We compare the diffusion constants\ndescribing the rates of these processes in such inhomogeneous systems to the\ndiffusion constants in the corresponding bulk liquid and vapor phases."
    },
    {
        "anchor": "Onsager reciprocal relations and chemo-mechanical coupling for\n  chemically-active colloids: Similar to cells, bacteria, and other microorganisms, synthetic\nchemically-active colloids can harness the energy from their environment\nthrough a surface chemical reaction and use its energy to self-propel in\nfluidic environments. In this paper, we study the chemo-mechanical coupling\nthat leads to the self-propulsion of chemically active colloids. The coupling\nbetween chemical reactions and momentum transport is a consequence of the\nOnsager reciprocal relations. They state that the velocity and the surface\nreaction rate are related to the mechanical and chemical affinities through a\nsymmetric matrix. A consequence of the Onsager reciprocal relations is that, if\na chemical reaction drives the motion of the colloid, then an external force\ngenerates a reaction rate. Here, we investigate the Onsager reciprocal\nrelations for a spherical active colloid that catalyzes a reversible surface\nchemical reaction between two species. We solve the relevant transport\nequations using a perturbation expansion and numerical simulations to\ndemonstrate the validity of the reciprocal relations around the equilibrium.\nOur results are consistent with previous studies and highlight the key role of\nsolute advection in preserving the symmetry of the Onsager matrix. Finally, we\nshow that the Onsager reciprocal relations break down around a nonequilibrium\nsteady state, which has implications for the thermal fluctuations of the active\ncolloids used in experiments.",
        "positive": "Off-equilibrium dynamics in the energy landscape of a simple model glass: The aging dynamics of a simple model glass is numerically investigated\nobserving how it takes place in the potential energy landscape $V$.\nPartitioning the landscape in basins of minima of $|\\nabla V|^2$, we are able\nto elucidate some interesting topological properties of the aging process. The\nmain result is the characterization of the long time behavior as a jump\ndynamics between basins of attraction of minima. Moreover we extract some\ninformation about the landscape itself, determining quantitatively few\nparameters describing it, such as the mean energy barrier value and the mean\nsquare distance between adjacent minima."
    },
    {
        "anchor": "Structural Origin of the Two-Step Glass Transition: The glass transition is a long-standing problem in physics. Identifying the\nstructural origin of the transition may lead to the ultimate solution to the\nproblem. Here, for the first time, we discover such a structural origin by\nproposing a novel method to analyze structure-dynamics relation in glasses. An\ninteresting two-step glass transition, with rotational glass transition\npreceding translational one, is identified experimentally in 2D colloidal rod\nsystems. During the transition, parallel and perpendicularly packed rods are\nfound to form local free energy minima in configurational space, separated by\nan activation barrier. This barrier increases significantly when rotational\nglass transition is approached; thereby the rotational motion is frozen while\nthe translational one remains diffusive. We argue that the activation barrier\nfor rotation is the origin of the two-step glass transition. Such an activation\nbarrier between well-defined local configurations holds the key to understand\nthe two-step glass transition in general.",
        "positive": "The first jamming crossover: geometric and mechanical features: The jamming transition characterizes athermal systems of particles\ninteracting via finite range repulsive potentials, and occurs on increasing the\ndensity when particles cannot avoid making contacts with those of their first\ncoordination shell. We have recently shown [M. Pica Ciamarra and P. Sollich,\narXiv:1209.3334] that the same systems are also characterized by a series of\njamming crossovers. These occur at higher volume fractions as particles are\nforced to make contact with those of subsequent coordination shells. At finite\ntemperature, the crossovers give rise to dynamic and thermodynamic density\nanomalies, including a diffusivity anomaly and a negative thermal expansion\ncoefficient. Density anomalies may therefore be related to structural changes\noccurring at the jamming crossovers. Here we elucidate these structural\nchanges, investigating the evolution of the structure and of the mechanical\nproperties of a jammed system as its volume fraction varies from the jamming\ntransition to and beyond the first jamming crossover. We show that the first\njamming crossover occurs at a well defined volume fraction, and that it induces\na rearrangement of the force network causing a softening of the system. It also\ncauses qualitative changes in the normal mode density of states and the spatial\nproperties of the normal mode vectors."
    },
    {
        "anchor": "Bidirectional cooperative motion of myosin-II motors on actin tracks\n  with randomly alternating polarities: The cooperative action of many molecular motors is essential for dynamic\nprocesses such as cell motility and mitosis. This action can be studied by\nusing motility assays in which the motion of cytoskeletal filaments over a\nsurface coated with motor proteins is tracked. In previous studies of\nactin-myosin II systems, fast directional motion was observed, reflecting the\ntendency of myosin II motors to propagate unidirectionally along actin\nfilaments. Here, we present a motility assay with actin bundles consisting of\nshort filamentous segments with randomly alternating polarities. These actin\ntracks exhibit bidirectional motion with macroscopically large time intervals\n(of the order of several seconds) between direction reversals. Analysis of this\nbidirectional motion reveals that the characteristic reversal time,\n$\\tau_{rev}$, does not depend on the size of the moving bundle or on the number\nof motors, $N$. This observation contradicts previous theoretical calculations\nbased on a two-state ratchet model [Badoual et al., Proc. Natl. Acad. Sci. USA,\nvol. 99, p. 6696 (2002)], predicting an exponential increase of $\\tau_{rev}$\nwith $N$. We present a modified version of this model that takes into account\nthe elastic energy due to the stretching of the actin track by the myosin II\nmotors. The new model yields a very good quantitative agreement with the\nexperimental results.",
        "positive": "The Knudsen temperature jump and the Navier-Stokes hydrodynamics of\n  granular gases driven by thermal walls: Thermal wall is a convenient idealization of a rapidly vibrating plate used\nfor vibrofluidization of granular materials. The objective of this work is to\nincorporate the Knudsen temperature jump at thermal wall in the Navier-Stokes\nhydrodynamic modeling of dilute granular gases of monodisperse particles that\ncollide nearly elastically. The Knudsen temperature jump manifests itself as an\nadditional term, proportional to the temperature gradient, in the boundary\ncondition for the temperature. Up to a numerical pre-factor of order unity,\nthis term is known from kinetic theory of elastic gases. We determine the\npreviously unknown numerical pre-factor by measuring, in a series of molecular\ndynamics (MD) simulations, steady-state temperature profiles of a gas of\nelastically colliding hard disks, confined between two thermal walls kept at\ndifferent temperatures, and comparing the results with the predictions of a\nhydrodynamic calculation employing the modified boundary condition. The\nmodified boundary condition is then applied, without any adjustable parameters,\nto a hydrodynamic calculation of the temperature profile of a gas of inelastic\nhard disks driven by a thermal wall. We find the hydrodynamic prediction to be\nin very good agreement with MD simulations of the same system. The results of\nthis work pave the way to a more accurate hydrodynamic modeling of driven\ngranular gases."
    },
    {
        "anchor": "Intrinsic profiles and capillary waves at homopolymer interfaces: a\n  Monte Carlo study: A popular concept which describes the structure of polymer interfaces by\n``intrinsic profiles'' centered around a two dimensional surface, the ``local\ninterface position'', is tested by extensive Monte Carlo simulations of\ninterfaces between demixed homopolymer phases in symmetric binary (AB)\nhomopolymer blends, using the bond fluctuation model. The simulations are done\nin an LxLxD geometry. The interface is forced to run parallel to the LxL planes\nby imposing periodic boundary conditions in these directions and fixed boundary\nconditions in the D direction, with one side favoring A and the other side\nfavoring B. Intrinsic profiles are calculated as a function of the ``coarse\ngraining length'' B by splitting the system into columns of size BxBxD and\naveraging in each column over profiles relative to the local interface\nposition. The results are compared to predictions of the self-consistent field\ntheory. It is shown that the coarse graining length can be chosen such that the\ninterfacial width matches that of the self-consistent field profiles, and that\nfor this choice of B the ``intrinsic'' profiles compare well with the\ntheoretical predictions.",
        "positive": "On the accurate computation of the true contact-area in mechanical\n  contact of random rough surfaces: We introduce a corrective function to compensate errors in contact area\ncomputations coming from mesh discretization. The correction is based on\ngeometrical arguments and requires only one additional quantity to be computed:\nthe length of contact/non-contact interfaces. The new technique enables us to\nevaluate accurately the true contact area using a coarse mesh for which the\nshortest wavelength in the surface spectrum reaches the grid size. The validity\nof the approach is demonstrated for surfaces with different fractal dimensions\nand different spectral content using a properly designed mesh convergence test.\nIn addition, we use a topology preserving smoothing technique to adjust the\nmorphology of contact clusters obtained with a coarse grid."
    },
    {
        "anchor": "Structural Transitions and Soft Modes in Frustrated DNA Crystals: Relying on symmetry considerations appropriate for helical biopolymers such\nas DNA and filamentous actin, we argue that crystalline packings of mutually\nrepulsive helical macromolecules fall principally into two categories:\nunfrustrated (hexagonal) and frustrated (rhombohedral). For both cases, we\nconstruct the Landau-Ginzburg free energy for the 2D columnar-hexagonal to 3D\ncrystalline phase transition, including the coupling between molecular\ndisplacements {\\it along} biopolymer backbone to displacements in the plane of\nhexagonal order. We focus on the distinct elastic properties that emerge upon\ncrystallization of helical arrays due to this coupling. Specifically, we\ndemonstrate that frustrated states universally exhibit a highly anisotropic\nin-plane elastic response, characterized by an especially soft compliance to\nsimple-shear deformations and a comparatively large resistance to those\ndeformations that carry the array from the low- to high-density crystalline\nstates of DNA.",
        "positive": "Nontrivial rheological exponents in sheared yield stress fluids: In this work we discuss possible physical origins for non-trivial exponents\nin the athermal rheology of soft materials at low but finite driving rates. A\nkey ingredient in our scenario is the presence of a self-consistent mechanical\nnoise that stems from the spatial superposition of long-range elastic responses\nto localized plastically deforming regions. We study analytically a mean-field\nmodel, in which this mechanical noise is accounted for by a stress diffusion\nterm coupled to the plastic activity. Within this description we show how a\ndependence of the shear modulus and/or the local relaxation time on the shear\nrate introduces corrections to the usual mean-field prediction, concerning the\nHerschel-Bulkley-type rheological response of exponent 1/2. This feature of the\nmean-field picture is then shown to be robust with respect to structural\ndisorder and partial relaxation of the local stress. We test this prediction\nnumerically on a mesoscopic lattice model that implements explicitly the\nlong-range elastic response to localized shear transformations, and we conclude\non how our scenario might be tested in rheological experiments."
    },
    {
        "anchor": "Thermodynamics of Charge Regulation Near Surface Neutrality: The interaction between two adjacent charged surfaces immersed in aqueous\nsolution is known to be affected by charge regulation - the modulation of\nsurface charge as two charged surfaces approach each other. This phenomenon is\nparticularly important near surface neutrality where the stability of objects\nsuch as colloids or biomolecules is jeopardized. Focusing on this ubiquitous\ncase, we elucidate the underlying thermodynamics and show that charge\nregulation is governed in this case by surface entropy. We derive explicit\nexpressions for charge regulation and formulate a new universal limiting law\nfor the free energy of ion adsorption to the surfaces. The latter turns out to\nbe proportional to $k_{B}T$, and independent of the association energy of ions\nto surface groups. These new results are applied to the analysis of unipolar as\nwell as amphoteric surfaces such as oxides near their point of zero charge or\nproteins near their isoelectric point.",
        "positive": "Tension, rigidity and preferential curvature of interfaces between\n  coexisting polymer solutions: The properties of the interface in a phase-separated solution of polymers\nwith different degrees of polymerization and Kuhn segment lengths are\ncalculated. The starting point is the planar interface, the profile of which is\ncalculated in the so-called 'blob model', which incorporates the solvent in an\nimplicit way. The next step is the study of a metastable droplet phase formed\nby imposing a chemical potential different from that at coexistence. The\npressure difference across the curved interface, which corresponds to this\nhigher chemical potential, is used to calculate the curvature properties of the\ndroplet. Interfacial tensions, Tolman lengths and rigidities are calculated and\nused for predictions for a realistic experimental case. The results suggest\nthat interfaces between phase-separated solutions of polymers exhibit, in\ngeneral, a preferential curvature, which stabilizes droplets of low molecular\nmass polymer in a high molecular mass macroscopic phase."
    },
    {
        "anchor": "Age dependent modes of extensional necking instability in soft glassy\n  materials: We study the instability to necking of an initially cylindrical filament of\nsoft glassy material subject to extensional stretching. By numerical simulation\nof the soft glassy rheology model and a simplified fluidity model, and by\nanalytical predictions within a highly generic toy description, we show that\nthe mode of instability is set by the age of the sample relative to the inverse\nof the applied extensional strain rate. Young samples neck gradually via a\nliquid-like mode, the onset of which is determined by both the elastic loading\nand plastic relaxation terms in the stress constitutive equation. Older samples\nfail at smaller draw ratios via a more rapid mode, the onset of which is\ndetermined only by the solid-like elastic loading terms (though plastic effects\narise later, once appreciable necking develops). We show this solid-like mode\nto be the counterpart, for elastoplastic materials, of the Consid\\`ere mode of\nnecking in strain-rate-independent solids.",
        "positive": "Master curve of boosted diffusion for ten catalytic enzymes: Molecular agitation more rapid than thermal Brownian motion is reported for\ncellular environments, motor proteins, synthetic molecular motors, enzymes, and\ncommon chemical reactions, yet that chemical activity couples to molecular\nmotion contrasts with generations of accumulated knowledge about diffusion at\nequilibrium. To test the limits of this idea, a critical testbed is mobility of\ncatalytically active enzymes. Sentiment is divided about reality of enhanced\nenzyme diffusion with evidence for and against. Here a master curve shows that\nenzyme diffusion coefficient increases in proportion to the energy release\nrate, the product of Michaelis-Menten reaction rate and Gibbs free energy\nchange with the highly satisfactory correlation coefficient of 0.97. For ten\ncatalytic enzymes (urease, acetylcholinesterase, seven enzymes from the glucose\ncascade cycle, and another), our measurements span from roughly 40% enhanced\ndiffusion coefficient at high turnover rate and negative Gibbs free energy to\nno enhancement at slow turnover rate and positive Gibbs free energy. Moreover,\ntwo independent measures of mobility show consistency, provided that one avoids\nundesirable fluorescence photophysics. The master curve presented here\nquantifies the limits of both ideas, that enzymes display enhanced diffusion\nand that they do not within instrumental resolution, and has possible\nimplications for understanding enzyme mobility in cellular environments. The\nstriking linear dependence for the exergonic enzymes (negative Gibbs free\nenergy) together with the vanishing effect for endergonic enzyme (positive\nGibbs free energy) are consistent with a physical picture where the mechanism\nboosting the diffusion is an active one, utilizing the available work from the\nchemical reaction."
    },
    {
        "anchor": "Cellular and Developmental Basis of Avian Structural Coloration: Vivid structural colors in birds are a conspicuous and vital part of their\nphenotype. They are produced by a rich diversity of integumentary photonic\nnanostructures in skin and feathers. Unlike pigmentary coloration, whose\nmolecular genetic basis is being elucidated, little is known regarding the\npathways underpinning organismal structural coloration. Here, we review\navailable data on the development of avian structural colors. In particular,\nfeather photonic nanostructures are understood to be intracellularly\nself-assembled by physicochemical forces typically seen in soft colloidal\nsystems. We identify promising avenues for future research that can address\ncurrent knowledge gaps, which is also highly relevant for the sustainable\nengineering of advanced bioinspired and biomimetic materials.",
        "positive": "Modelling approaches to the dewetting of evaporating thin films of\n  nanoparticle suspensions: We review recent experiments on dewetting thin films of evaporating colloidal\nnanoparticle suspensions (nanofluids) and discuss several theoretical\napproaches to describe the ongoing processes including coupled transport and\nphase changes. These approaches range from microscopic discrete stochastic\ntheories to mesoscopic continuous deterministic descriptions. In particular, we\ndescribe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density\nfunctional theory and (iii) a hydrodynamic thin film model.\n  Models (i) and (ii) are employed to discuss the formation of polygonal\nnetworks, spinodal and branched structures resulting from the dewetting of an\nultrathin 'postcursor film' that remains behind a mesoscopic dewetting front.\nWe highlight, in particular, the presence of a transverse instability in the\nevaporative dewetting front, which results in highly branched fingering\nstructures. The subtle interplay of decomposition in the film and contact line\nmotion is discussed.\n  Finally, we discuss a simple thin film model (iii) of the hydrodynamics on\nthe mesoscale. We employ coupled evolution equations for the film thickness\nprofile and mean particle concentration. The model is used to discuss the\nself-pinning and depinning of a contact line related to the 'coffee-stain'\neffect.\n  In the course of the review we discuss the advantages and limitations of the\ndifferent theories, as well as possible future developments and extensions."
    },
    {
        "anchor": "Elasticity from the Force Network Ensemble in Granular Media: Transmission of forces in static granular materials are studied within the\nframework of the force network ensemble, by numerically evaluating the\nmechanical response of hexagonal packings of frictionless grains and\nrectangular packings of frictional grains. In both cases, close to the point of\napplication of the overload, the response is non-linear and displays two peaks,\nwhile at larger length-scales it is linear and elastic-like. The cross-over\nbetween these two behaviors occurs at a depth that increases with the magnitude\nof the overload, and decreases with increasing friction.",
        "positive": "Achievements and challenges of nanostructured Titania Eco-materials\n  derived from Sol-Gel Processing: Nanostructured titania derived from the sol-gel processing requires a\ndetailed study to clarify state-of-art of every process step starting from\ncolloidal sol, peptization, gelation to the final sintering. The applied\nparameters such as peptization temperature and time in the current\ninvestigation of sol during the early stage of processing were characterized by\ndynamic light scattering (DLS) and compared to other parameters found in the\nliterature. Upon gelation, the resulting anatase was calcined to study the\nphase transformation to rutile as well as to discriminate the effect of\npeptized and unpeptized in which the characterizations were carried out by\nusing XRD, Nitrogen adsorption-desorption isotherm and HRTEM. It shows that\npeptizing the titania sol at 80oC for at least 12 h resulted in a small and\nuniform anatase crystallite with size of 4.6 nm."
    },
    {
        "anchor": "Test of a scaling hypothesis for the structure factor of disordered\n  diblock copolymer melts: Coarse-grained theories of dense polymer liquids such as block copolymer\nmelts predict a universal dependence of equilibrium properties on a few\ndimensionless parameters. For symmetric diblock copolymer melts, such theories\npredict a universal dependence on only chi N and Nbar, where chi is an\neffective interaction parameter, N is a degree of polymerization, and Nbar is a\nmeasure of overlap. We test whether simulation results for the structure factor\nS(q) obtained from several different simulation models are consistent with this\ntwo-parameter scaling hypothesis. We compare results from three models: (1) a\nlattice Monte Carlo model, the bond-fluctuation model, (2) a bead-spring model\nwith harsh repulsive interactions, similar to that of Kremer and Grest, and (3)\na bead-spring model with very soft repulsion between beads, and strongly\noverlapping beads. We compare results from pairs of simulations of different\nmodels that have been designed to have matched values of Nbar, over a range of\nvalues of chi N and N, and devise methods to test the scaling hypothesis\nwithout relying on any prediction for how the phenomenological interaction\nparameter chi depends on more microscopic parameters. The results strongly\nsupport the scaling hypothesis, even for rather short chains, confirming that\nit is indeed possible to give an accurate universal description of simulation\nmodels that differ in many details.",
        "positive": "Dynamics of magnetic nanoparticle suspensions: We study the dynamics of a suspension of magnetic nanoparticles. Their\nrelaxation times are strongly size-dependent. The dominant mode of relaxation\nis also governed by the size of the particles. As a result the dynamics is\ngreatly altered due to polydispersity in the sample. We study the effect of\npolydispersity on the response functions. These exhibit significant changes as\nthe parameters characterizing polydispersity are varied. We also provide a\nprocedure to extract the particle size distribution in a polydisperse sample\nusing Cole-Cole plots. Further the presence of attractive interactions causes\naggregation of particles leading to the formation of clusters. Repulsive\ninteractions along with thermal disorder not only hinder aggregation, but also\nintroduce the possibility of removal of particles or \"fragmentation\" from\nclusters. The competing mechanisms of aggregation and fragmentation yield a\ndistribution of cluster sizes in the steady-state. We attempt to understand the\nformation of clusters and their distributions using a model incorporating the\nphenomena of aggregation and fragmentation. Scaling forms for quantities of\ninterest have been obtained. Finally we compare our numerical results with\nexperimental data. These comparisons are satisfactory."
    },
    {
        "anchor": "Magnetically powered metachronal waves induce locomotion in\n  self-assemblies: When tiny soft ferromagnetic particles are placed along a liquid interface\nand exposed to a vertical magnetic field, the balance between capillary\nattraction and magnetic repulsion leads to self-organization into well-defined\npatterns. Here, we demonstrate experimentally that precessing magnetic fields\ninduce metachronal waves on the periphery of these assemblies, similar to the\nones observed in ciliates and some arthropods. The outermost layer of particles\nbehaves like an array of cilia or legs whose sequential movement causes a net\nand controllable locomotion. This bioinspired many-particle swimming strategy\nis effective even at low Reynolds number, using only spatially uniform fields\nto generate the waves.",
        "positive": "Orientational relaxation in a discotic liquid crystal: We investigate orientational relaxation of a model discotic liquid crystal,\nconsists of disc-like molecules, by molecular dynamics simulations along two\nisobars starting from the high temperature isotropic phase. The two isobars\nhave been so chosen that (A) the phase sequence isotropic (I)-nematic\n(N)-columnar (C) appears upon cooling along one of them and (B) the sequence\nisotropic (I)-columnar (C) along the other. While the orientational relaxation\nin the isotropic phase near the I-N phase transition in system (A) shows a\npower law decay at short to intermediate times, such power law relaxation is\nnot observed in the isotropic phase near the I-C phase boundary in system (B).\nIn order to understand this difference (the existence or the absence of the\npower law decay), we calculated the the growth of the orientational pair\ndistribution functions (OPDF) near the I-N phase boundary and also near the I-C\nphase boundary. We find that OPDF shows a marked growth in long range\ncorrelation as the I-N phase boundary is approached in the I-N-C system (A),\nbut such a growth is absent in the I-C system, which appears to be consistent\nwith the result that I-N phase transition in the former is weakly first order\nwhile the the I-C phase transition in the later is not weak. As the system\nsettles into the nematic phase, the decay of the single-particle second-rank\norientational OTCF follows a pattern that is similar to what is observed with\ncalamitic liquid crystals and supercooled molecular liquids."
    },
    {
        "anchor": "Structural relaxation of polydisperse hard spheres: comparison of the\n  mode-coupling theory to a Langevin dynamics simulation: We analyze the slow, glassy structural relaxation as measured through\ncollective and tagged-particle density correlation functions obtained from\nBrownian dynamics simulations for a polydisperse system of quasi-hard spheres\nin the framework of the mode-coupling theory of the glass transition (MCT).\nAsymptotic analyses show good agreement for the collective dynamics when\npolydispersity effects are taken into account in a multi-component calculation,\nbut qualitative disagreement at small $q$ when the system is treated as\neffectively monodisperse. The origin of the different small-$q$ behaviour is\nattributed to the interplay between interdiffusion processes and structural\nrelaxation. Numerical solutions of the MCT equations are obtained taking\nproperly binned partial static structure factors from the simulations as input.\nAccounting for a shift in the critical density, the collective density\ncorrelation functions are well described by the theory at all densities\ninvestigated in the simulations, with quantitative agreement best around the\nmaxima of the static structure factor, and worst around its minima. A\nparameter-free comparison of the tagged-particle dynamics however reveals large\nquantiative errors for small wave numbers that are connected to the well-known\ndecoupling of self-diffusion from structural relaxation and to dynamical\nheterogeneities. While deviations from MCT behaviour are clearly seen in the\ntagged-particle quantities for densities close to and on the liquid side of the\nMCT glass transition, no such deviations are seen in the collective dynamics.",
        "positive": "Emergence of interparticle friction in attractive colloidal matter: Interparticle friction plays a governing role in the mechanics of particulate\nmaterials. However, virtually all experimental studies to date rely on\nmeasuring macroscopic responses, and as such it remains largely unknown how\nfrictional effects emerge at the microscopic level. This is particularly\nchallenging in systems subject to thermal fluctuations due to the transient\nnature of interparticle contacts. Here, we directly relate particle-level\nfrictional arrest to local coordination in an attractive colloidal model\nsystem. We reveal that the orientational dynamics of particles slows down\nexponentially with increasing coordination number due to the emergence of\nfrictional interactions, the strength of which can be tuned simply by varying\nthe attraction strength. Using a simple computer simulation model, we uncover\nhow the interparticle interactions govern the formation of frictional contacts\nbetween particles. Our results establish quantitative relations between\nfriction, coordination and interparticle interactions. This is a key step\ntowards using interparticle friction to tune the mechanical properties of\nparticulate materials."
    },
    {
        "anchor": "Wetting of cholesteric liquid crystals: We investigate theoretically the wetting properties of cholesteric liquid\ncrystals at a planar substrate. If the properties of substrate and of the\ninterface are such that the cholesteric layers are not distorted the wetting\nproperties are similar to those of a nematic liquid crystal. If, on the other\nhand, the anchoring conditions force the distortion of the liquid crystal\nlayers the wetting properties are altered, the free cholesteric-isotropic\ninterface is non-planar and there is a layer of topological defects close to\nthe substrate. These deformations can either promote or hinder the wetting of\nthe substrate by a cholesteric, depending on the properties of the cholesteric\nliquid crystal.",
        "positive": "Diffusion coefficient for reptation of polymers with kinematic disorder: We give a lower bound on the diffusion coefficient of a polymer chain in an\nentanglement network with kinematic disorder, which is obtained from an exact\ncalculation in a modified Rubinstein-Duke lattice gas model with periodic\nboundary conditions. In the limit of infinite chain length we show the\ndiffusive motion of the polymer to be slowed down by kinematic disorder by the\nsame factor as for a single particle in a random barrier model."
    },
    {
        "anchor": "Prescribing patterns in growing tubular soft matter by initial residual\n  stress: Initial residual stress is omnipresent in biological tissues and soft matter,\nand can affect growth-induced pattern selection significantly. Here we\ndemonstrate this effect experimentally by letting soft tubes grow in the\npresence or absence of initial residual stress and by observing different\ngrowth pattern evolutions. These experiments motivate us to model the\nmechanisms at play when a growing bilayer tubular organ spontaneously displays\nbuckling patterns on its inner surface. We demonstrate that not only\ndifferential growth, geometry and elasticity, but also initial residual stress\ndistribution, exert a notable influence on these pattern phenomena. Prescribing\nan initial residual stress distribution offers an alternative or a more\neffective way to implement pattern selection for growable bio-tissues or soft\nmatter. The results also show promise for the design of 4D bio-mimic printing\nprotocols or for controlling hydrogel actuators.",
        "positive": "Gelation as condensation frustrated by hydrodynamics and mechanical\n  isostaticity: Colloidal gels have unique mechanical and transport properties that stem from\ntheir bicontinous nature, in which a colloidal network is intertwined with a\nviscous solvent, and have found numerous applications in foods, cosmetics,\nconstruction materials, and for medical applications, such as cartilage\nreplacements. So far, our understanding of the process of colloidal gelation is\nlimited to long-time dynamical effects, where gelation is viewed as a phase\nseparation process interrupted by the glass transition. However, this picture\nneglects two important effects: the influence of hydrodynamic interactions, and\nthe emergence of mechanical stability. With confocal microscopy experiments,\nhere we successfully follow the entire process of gelation with a\nsingle-particle resolution, yielding time-resolved measures of internal stress\nand viscoelasticity from the very beginning of the aggregation process. First,\nwe demonstrate that the incompressible nature of a liquid component constrains\nthe initial stage of phase separation, assisting the formation of a percolated\nnetwork. Then we show that this network is not mechanically stable and\nundergoes rearrangements driven by self-generated internal stress. Finally, we\nshow that mechanical metastability is reached only after percolation of locally\nisostatic environments, proving isostaticity a necessary condition for the\nstability and load bearing ability of gels rather than the glass transition.\nOur work reveals the crucial roles of momentum conservation in gelation in\naddition to the conventional purely out-of-equilibrium thermodynamic picture."
    },
    {
        "anchor": "Jamming of 3D Prolate Granular Materials: We have found that the ability of long thin rods to jam into a solid-like\nstate in response to a local perturbation depends upon both the particle aspect\nratio and the container size. The dynamic phase diagram in this parameter space\nreveals a broad transition region separating granular stick-slip and solid-like\nbehavior. In this transition region the pile displays both solid and stick-slip\nbehavior. We measure the force on a small object pulled through the pile, and\nfind the fluctuation spectra to have power law tails with an exponent\ncharacteristic of the region. The exponent varies from $\\beta=-2$ in the\nstick-slip region to $\\beta=-1$ in the solid region. These values reflect the\ndifferent origins -- granular rearrangements vs. dry friction -- of the\nfluctuations. Finally, the packing fraction shows only a slight dependence on\ncontainer size, but depends on aspect ratio in a manner predicted by a mean\nfield theory and implies an aspect-ratio independent contact number of $<c > =\n5.25 \\pm 0.03$.",
        "positive": "Elucidating the Role of Filament Turnover in Cortical Flow using\n  Simulations and Representation Learning: Cell polarization relies on long-range cortical flows, which are driven by\nactive stresses and resisted by the cytoskeletal network. While the general\nmechanisms that contribute to cortical flows are known, a quantitative\nunderstanding of the factors that tune flow speeds has remained lacking. Here,\nwe combine physical simulation, representation learning, and theory to\nelucidate the role of actin turnover in cortical flows. We show how turnover\ntunes the actin density and filament curvature and use representation learning\nto demonstrate that these quantities are sufficient to predict cortical flow\nspeeds. We extend a recent theory for contractility to account for filament\ncurvature in addition to the nonuniform distribution of crosslinkers along\nactin filaments due to turnover. We obtain formulas that can be used to fit\ndata from simulations and microscopy experiments. Our work provides insights\ninto the mechanisms of contractility that contribute to cortical flows and how\nthey can be controlled quantitatively."
    },
    {
        "anchor": "Pulling a polymer out of a potential well and the mechanical unzipping\n  of DNA: Motivated by the experiments on DNA under torsion, we consider the problem of\npulling a polymer out of a potential well by a force applied to one of its\nends. If the force is less than a critical value, then the process is activated\nand has an activation energy proportinal to the length of the chain. Above this\ncritical value, the process is barrierless and will occur spontaneously. We use\nthe Rouse model for the description of the dynamics of the peeling out and\nstudy the average behaviour of the chain, by replacing the random noise by its\nmean. The resultant mean-field equation is a nonlinear diffusion equation and\nhence rather difficult to analyze. We use physical arguments to convert this in\nto a moving boundary value problem, which can then be solved exactly. The\nresult is that the time $t_{po}$ required to pull out a polymer of $N$ segments\nscales like $N^2$. For models other than the Rouse, we argue that $t_{po}\\sim\nN^{1+\\nu}$",
        "positive": "Role of attractive forces in the relaxation dynamics of supercooled\n  liquids: The attractive tail of the intermolecular interaction affects very weakly the\nstructural properties of liquids, while it affects dramatically their dynamical\nones. Via the numerical simulations of model systems not prone to\ncrystallization, both in three and in two spatial dimensions, here we\ndemonstrate that the non-perturbative dynamical effects of the attractive\nforces are tantamount to a rescaling of the activation energy by the glass\ntransition temperature $T_g$: systems only differing in their attractive\ninteraction have the same structural and dynamical properties if compared at\nthe same value of $T/T_g$."
    },
    {
        "anchor": "Convective dispersion without molecular diffusion: A method-of-moments scheme is invoked to compute the asymptotic, long-time\nmean (or composite) velocity and dispersivity (effective diffusivity) of a\ntwo-state particle undergoing one-dimensional convective-diffusive motion\naccompanied by a reversible linear transition (``chemical reaction'' or\n``change in phase'') between these states. The instantaneous state-specific\nparticle velocity is assumed to depend only upon the instantaneous state of the\nparticle, and the transition between states is assumed to be governed by\nspatially-independent, first-order kinetics. Remarkably, even in the absence of\nmolecular diffusion, the average transport of the ``composite'' particle\nexhibits gaussian diffusive behavior in the long-time limit, owing to the\neffectively stochastic nature of the overall transport phenomena induced by the\ninterstate transition. The asymptotic results obtained are compared with\nnumerical computations.",
        "positive": "Relaxation dynamics in amorphous alloys under asymmetric cyclic shear\n  deformation: The influence of cyclic loading and glass stability on structural relaxation\nand yielding transition in amorphous alloys was investigated using molecular\ndynamics simulations. We considered a binary mixture cooled deep into the glass\nphase and subjected to cyclic shear deformation where strain varies\nperiodically but remains positive. We found that rapidly cooled glasses under\nasymmetric cyclic shear gradually evolve towards states with lower potential\nenergy and finite stress at zero strain. At the strain amplitude just below a\ncritical value, the rescaled distributions of nonaffine displacements converge\nto a power-law decay with an exponent of about -2 upon increasing number of\ncycles. By contrast, more stable glasses yield at lower strain amplitudes, and\nthe yielding transition can be delayed for hundreds of cycles when the strain\namplitude is near a critical value. These results can be useful for the design\nof novel thermo-mechanical processing methods to improve mechanical and\nphysical properties of metallic glasses."
    },
    {
        "anchor": "Cleaning ability of mixed solutions of sulfonated fatty acid methyl\n  esters: Here, we present results from a systematic study on cleaning of oily deposits\nfrom solid surfaces (porcelain and stainless steel) by solutions of fatty acid\nsulfonated methyl esters (SME), sodium salts. The zwitterionic\ndodecyldimethylamine oxide (DDAO) has been used as a cosurfactant. As\nrepresentatives of the vegetable and mineral oils, sunflower seed oil and light\nmineral oil have been used. The process of oil drop detachment from the solid\nsubstrates (roll-up mechanism) has been monitored. In the case of porcelain,\nexcellent cleaning of oil is achieved by mixed solutions of SME and DDAO. In\nthe case of stainless steel, excellent cleaning (superior than that by linear\nalkylbenzene sulfonate and sodium lauryl ether sulfate) is provided by binary\nand ternary mixtures of SMEs, which may contain also DDAO. For the studied\nsystems, the good cleaning correlates neither with the oil/water interfacial\ntension, nor with the surfactant chainlength and headgroup type. The data imply\nthat governing factors might be the thickness and morphology of admicelle\nlayers formed on the solid/water interface. The results indicate that the SME\nmixtures represent a promising system for formulations in house-hold\ndetergency, having in mind also other useful properties of SME, such as\nbiodegradability, skin compatibility and hard water tolerance.",
        "positive": "Splay--density coupling in semiflexible main-chain nematic polymers with\n  hairpins: We establish a macroscopic description of the splay--density coupling in\nsemiflexible main-chain nematic polymers with hairpins, using a vectorial\ncontinuity constraint for the \"recovered\" polar order of the chain tangents and\nintroducing chain backfolds (hairpins) as its new type of sources besides chain\nends. We treat both types of sources on a unified basis as a mixture of two\nideal gases with fixed composition. Performing detailed Monte Carlo simulations\nof nematic monodomain melts of \"soft\" worm-like chains with variable length and\nflexibility, we show via their structure factors that the chain backfolding\nweakens the splay--density coupling, and demonstrate how this weakening can be\nconsistently quantified on the macroscopic level. We also probe and discuss the\ndeviations from the noninteracting gas idealization of the chain ends and\nbackfolds."
    },
    {
        "anchor": "Topological waves in fluids with odd viscosity: Fluids in which both time-reversal and parity are broken can display a\ndissipationless viscosity that is odd under each of these symmetries. Here, we\nshow how this odd viscosity has a dramatic effect on topological sound waves in\nfluids, including the number and spatial profile of topological edge modes. Odd\nviscosity provides a short-distance cutoff that allows us to define a bulk\ntopological invariant on a compact momentum space. As the sign of odd viscosity\nchanges, a topological phase transition occurs without closing the bulk gap.\nInstead, at the transition point, the topological invariant becomes ill-defined\nbecause momentum space cannot be compactified. This mechanism is unique to\ncontinuum models and can describe fluids ranging from electronic to chiral\nactive systems.",
        "positive": "Entropy production in an elementary, light driven micro-machine: We consider the basic, thermodynamic properties of an elementary\nmicro-machine operating at colloidal length scales. In particular, we track and\nanalyse the driven stochastic motion of a carefully designed micro-propeller\nrotating unevenly in an optical tweezers, in water. In this intermediate\nregime, the second law of macroscopic thermodynamics is satisfied only as an\nensemble average, and individual trajectories can be temporarily associated\nwith decreases in entropy. We show that our light driven micro-propeller\nsatisfies an appropriate fluctuation theorem that constrains the probability\nwith which these apparent violations of the second law occur. Implications for\nthe development of more complex micro-machines are discussed."
    },
    {
        "anchor": "Double Helical Conformation and Extreme Rigidity in a Rodlike\n  Polyelectrolyte: The ubiquitous biomacromolecule DNA has an axial rigidity persistence length\nof ~50 nm, driven by its elegant double helical structure. While double and\nmultiple helix structures appear widely in nature, only rarely are these found\nin synthetic non-chiral macromolecules. Here we describe a double helical\nconformation in the densely charged aromatic polyamide\npoly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) or PBDT. This double helix\nmacromolecule represents one of the most rigid simple molecular structures\nknown, exhibiting an extremely high axial persistence length (~1 micrometer).\nWe present X-ray diffraction, NMR spectroscopy, and molecular dynamics (MD)\nsimulations that reveal and confirm the double helical conformation. The\ndiscovery of this extreme rigidity in combination with high charge density\ngives insight into the self-assembly of molecular ionic composites with high\nmechanical modulus (~1 GPa) yet with liquid-like ion motions inside, and\nprovides fodder for formation of new 1D-reinforced composites.",
        "positive": "Protein sizing with Differential Dynamic Microscopy: Introduced more than fifty years ago, dynamic light scattering is routinely\nused to determine the size distribution of colloidal suspensions, as well as of\nmacromolecules in solution, such as proteins, nucleic acids, and their\ncomplexes. More recently, differential dynamic microscopy has been proposed as\na way to perform dynamic light scattering experiments with a microscope, with\nmuch less stringent constraints in terms of cleanliness of the optical\nsurfaces, but a potentially lower sensitivity due to the use of camera-based\ndetectors. In this work, we push bright-field differential dynamic microscopy\nbeyond known limits and show it to be sufficiently sensitive to size small\nmacromolecules in diluted solutions. By considering solutions of three\ndifferent proteins (Bovine Serum Albumin, Lysozyme, and Pepsin), we accurately\ndetermine the diffusion coefficient and hydrodynamic radius of both single\nproteins and small protein aggregates down to concentrations of a few\nmilligrams per milliliter. In addition, we present preliminary results showing\nunexplored potential for the determination of virial coefficients. Our results\nare in excellent agreement with the ones obtained in parallel with a\nstate-of-the-art commercial dynamic light scattering setup, showing that\ndifferential dynamic microscopy represents a valuable alternative for rapid,\nlabel-free protein sizing with an optical microscope."
    },
    {
        "anchor": "Hard rectangles near curved hard walls: tuning the sign of the Tolman\n  length: Combining analytic calculations, computer simulations, and classical density\nfunctional theory we determine the interfacial tension of orientable\ntwo-dimensional hard rectangles near a curved hard wall. Both a circular cavity\nholding the particles and a hard circular obstacle surrounded by particles are\nconsidered. We focus on moderate bulk densities (corresponding to area\nfractions up to 50 percent) where the bulk phase is isotropic and vary the\naspect ratio of the rectangles and the curvature of the wall. The Tolman\nlength, which gives the leading curvature correction of the interfacial\ntension, is found to change sign at a finite density, which can be tuned via\nthe aspect ratio of the rectangles.",
        "positive": "Density Functional approach to Nonlinear Rheology: We present a density functional based closure of the pair Smoluchowski\nequation for Brownian particles under shear flow. Given an equilibrium free\nenergy functional as input the theory provides first-principles predictions for\nthe flow-distorted pair correlation function and associated rheological\nquantities over a wide range of volume fractions and flow rates. Taking\ntwo-dimensional hard-disks under shear flow as an illustrative model we\ncalculate the pair correlation function, viscosity and normal stress difference\nunder both steady and start-up shear."
    },
    {
        "anchor": "Self-organized Archimedean Spiral Pattern: Regular Bundling of Fullerene\n  through Solvent Evaporation: We report the spontaneous generation of an Archimedean spiral pattern of\nfullerene via the evaporation of solvent. The self-organized spiral pattern\nexhibited equi-spacing on the order of micrometer between neighboring stripes.\nThe characteristics of the spirals, such as the spacing between stripes, the\nnumber of stripes and the band width of stripes, could be controlled by tuning\nthe thickness of the liquid bridge and the concentration of solution. The\nmechanism of pattern formation is interpreted in terms of a specific traveling\nwave on the liquid-solid interface accompanied by a stick-slip process of the\ncontact line.",
        "positive": "Formation of solitons in atomic Bose-Einstein condensates by dark-state\n  adiabatic passage: We propose a new method of creating solitons in elongated Bose-Einstein\nCondensates (BECs) by sweeping three laser beams through the BEC. If one of the\nbeams is in the first order (TEM10) Hermite-Gaussian mode, its amplitude has a\ntransversal phase slip which can be transferred to the atoms creating a\nsoliton. Using this method it is possible to circumvent the restriction set by\nthe diffraction limit inherent to conventional methods such as phase\nimprinting. The method allows one to create multicomponent (vector) solitons of\nthe dark-bright form as well as the dark-dark combination. In addition it is\npossible to create in a controllable way two or more dark solitons with very\nsmall velocity and close to each other for studying their collisional\nproperties."
    },
    {
        "anchor": "Computational Indentation in Highly Cross-linked Polymer Networks: Indentation is a common experimental technique to study the mechanics of\npolymeric materials. The main advantage of using indentation is because this\nprovides a direct correlation between the microstructure and the small-scale\nmechanical response, which is otherwise difficult within the standard tensile\ntesting. Here, majority of studies have investigated hydrogels, microgels\nand/or elastomers. However, a lesser investigated system is the indentation in\nhighly cross-linked polymer (HCP) networks, where the complex network structure\nplays a key role in dictating their physical properties. In this work, we\ninvestigate the structure-property relationship in HCP networks using the\ncomputational indentation of a generic model. We establish a correlation\nbetween the local bond breaking, the network rearrangement, and the small-scale\nmechanics. The results are compared with the elastic-plastic deformation model.\nHCPs harden upon indentation.",
        "positive": "Ultrasound-propelled nano- and microspinners: We study nonhelical nano- and microparticles that, through a particular\nshape, rotate when they are exposed to ultrasound. Employing acoustofluidic\ncomputer simulations, we investigate the flow field that is generated around\nthese particles in the presence of a planar traveling ultrasound wave as well\nas the resulting propulsion force and torque of the particles. We study how the\nflow field and the propulsion force and torque depend on the particles'\norientation relative to the propagation direction of the ultrasound wave.\nFurthermore, we show that the orientation-averaged propulsion force vanishes\nwhereas the orientation-averaged propulsion torque is nonzero. Thus, we reveal\nthat these particles can constitute nano- and microspinners that persistently\nrotate in isotropic ultrasound."
    },
    {
        "anchor": "Evaporation of tiny water aggregation on solid surfaces of different\n  wetting properties: The evaporation of a tiny amount of water on the solid surface with different\nwettability has been studied by molecular dynamics simulations. We found that,\nas the surface changed from hydrophobicity to hydrophility, the evaporation\nspeed did not show a monotonically decrease from intuition, but increased\nfirst, and then decreased after reached a maximum value. The competition\nbetween the number of the water molecules on the water-gas surface from where\nthe water molecules can evaporate and the potential barrier to prevent those\nwater molecules from evaporating results in the unexpected behavior of the\nevaporation. A theoretical model based on those two factors can fit the\nsimulation data very well. This finding is helpful in understanding the\nevaporation on the biological surfaces, designing artificial surface of ultra\nfast water evaporating or preserving water in soil.",
        "positive": "Potential Energy Landscape of a Flexible Water Model: Equation-of-State,\n  Configurational Entropy, and Adam-Gibbs Relationship: The potential energy landscape (PEL) formalism is a tool within statistical\nmechanics that has been used in the past to calculate the equation of states\n(EOS) of classical rigid model liquids at low temperatures, where computer\nsimulations may be challenging. In this work, we use classical molecular\ndynamics (MD) simulations and the PEL formalism to calculate the EOS of the\nflexible q-TIP4P/F water model. This model exhibits a liquid-liquid critical\npoint (LLCP) in the supercooled regime, at ($P_c = 150$ MPa, $T_c = 190$ K,\n$\\rho_c = 1.04$ g/cm$^3$) [using the reaction field technique]. The PEL-EOS of\nq-TIP4P/F water, and the corresponding location of the LLCP, are in very good\nagreement with the MD simulations. We show that the PEL of q-TIP4P/F water is\nGaussian which allows us to calculate the configurational entropy of the\nsystem, $S_{conf}$. The $S_{conf}$ of q-TIP4P/F water is surprisingly similar\nto that reported previously for rigid water models, suggesting that\nintramolecular flexibility does not necessarily add roughness to the PEL. We\nalso show that the Adam-Gibbs relation, which relates the diffusion coefficient\n$D$ with $S_{conf}$, holds for the flexible q-TIP4P/F water model. Overall, our\nresults indicate that the PEL formalism can be used to study molecular systems\nthat include molecular flexibility, the common case in standard force fields.\nThis is not trivial since the introduction of large bending/stretching mode\nfrequencies is problematic in classical statistical mechanics. For example, as\nshown previously, we find that such high-frequencies lead to an unphysical\n(negative) entropy for q-TIP4P/F water (yet the PEL formalism can be applied\nsuccessfully)."
    },
    {
        "anchor": "Elongation of discotic liquid crystal strands and lubricant effects: After a short review on the physics of pulled threads and their mechanical\nproperties, the paper reports and discusses on the strand elongation of\ndisordered columnar phases, hexagonal or lamello-columnar, of small molecules\nor polymers. The mechanical properties appear to be relevant to the length of\nthe columns of molecules compared to the thread length, instead of the usual\ncorrelation length. When short, the column entanglement being taken into\naccount, the strand exhibits rather fluid properties that may even look like\nnematic at a macroscopic scale. Then, the Plateau-Rayleigh instability soon\nbreaks the thread. However, the hydrodynamic objects being the columns instead\nof the molecules, the viscosity is anomalously large. The observations show\nthat the strands of columnar phases are made of filaments, or fibrils, that\nindeed are bundles of columns of molecules. They both explain the grooves and\nrings observed on the antenna or bamboo-like strand profiles. On pulling a\nstrand, the elongation stress eventually exceeds the plasticity threshold, thus\nbreaking columns and filaments. Cracks, more exactly, giant dislocations are\nthus formed. They change the strand thickness by steps of different\nbirefringence colours. Interestingly, adding a solute may drastically change\nthe effective viscosity of the columnar phase and its mechanical properties.\nSome solutes as alcanes, exhibit lubricant and detangling properties, while\nothers as triphenylene, are quite anti-lubricant.",
        "positive": "Low-Reynolds-number, bi-flagellated Quincke swimmers with multiple forms\n  of motion: In the limit of zero Reynolds number (Re), swimmers propel themselves\nexploiting a series of non-reciprocal body motions. For an artificial swimmer,\na proper selection of the power source is required to drive its motion, in\ncooperation with its geometric and mechanical properties. Although various\nexternal fields (magnetic, acoustic, optical, etc.) have been introduced,\nelectric fields are rarely utilized to actuate such swimmers experimentally in\nunbounded space. Here we use uniform and static electric fields to demonstrate\nlocomotion of a bi-flagellated sphere at low Re via Quincke rotation. These\nQuincke swimmers exhibit three different forms of motion, including a\nself-oscillatory state due to elasto-electro-hydrodynamic interactions. Each\nform of motion follows a distinct trajectory in space. Our experiments and\nnumerical results demonstrate a new method to generate, and potentially\ncontrol, the locomotion of artificial flagellated swimmers."
    },
    {
        "anchor": "Modifying Fragility and Collective Motion in Polymer Melts with\n  Nanoparticles: We investigate the impact of nanoparticles (NP) on the fragility and\ncooperative string-like motion in a model glass-forming polymer melt by\nmolecular dynamics simulation. The NP cause significant changes to both the\nfragility and the average length of string-like motion, where the effect\ndepends on the NP-polymer interaction and the NP concentration. We interpret\nthese changes via the Adam-Gibbs (AG) theory, assuming the strings can be\nidentified with the \"cooperatively rearranging regions\" of AG. Our findings\nindicate fragility is primarily a measure of the temperature dependence of the\ncooperativity of molecular motion.",
        "positive": "Emergent dynamics due to chemo-hydrodynamic self-interactions in active\n  polymers: We create freely-jointed active polymers using self-propelled droplets as\nmonomeric units, and show that self-shaping chemo-hydrodynamic interactions\nwithin the polymer result in novel dissipative structures and steady-states.\nOur experiments reveal that the interactions between the monomeric droplets\ngive rise to ballistic propulsion of the active polymers and is associated with\nrigidity and stereotypical shapes of the polymers. These traits, quantified by\nthe curvatures and speeds of the active polymers, vary systematically with the\nchain length. Using simulations of a minimal model, we establish that the\nemergent propulsion and rigidity are a generic consequence of quasi\ntwo-dimensional confinement and auto-repulsive chemical interactions between\nthe freely jointed active droplets. Finally, we tune the interplay between the\nchemical and hydrodynamic fields to experimentally demonstrate oscillatory\ndynamics of the rigid polymer propulsion. Altogether, our work highlights the\npossible first steps towards synthetic self-morphic active matter."
    },
    {
        "anchor": "Ionic mixtures in two dimensions: from crystals to chain and dipole\n  gases: The ground state of a two-dimensional ionic mixture composed of oppositely\ncharged spheres is determined as a function of the size asymmetry by using a\npenalty method. The cascade of stable structures includes square, triangular\nand rhombic crystals as well as a dipolar pair gas and a gas of one-dimensional\ncrystalline chains. Thereby we confirm the square structure, found\nexperimentally on charged granulates, and predict new phases detectable in\nexperiments on granular and colloidal matter.",
        "positive": "Sculpting liquid crystal skyrmions with external flows: We investigate, using experiments and numerical simulations, the distortions\nand the alignment of skyrmions in the liquid crystal under external flows for a\nrange of average flow velocities. The simulations are based on the Landau-de\nGennes $Q$ tensor theory both for isolated as well as for systems with many\nskyrmions. We found striking flow-driven elongation of an isolated skyrmion and\nflow alignment of skyrmions in the many-skyrmion system, both of which are also\nobserved in the experiments. In the simulations, particular attention was given\nto the dissipation rate and to the various dissipation channels for a single\nskyrmion under external flow. This analysis provides insight on the observed\nscaling regime of the elongation of isolated flowing skyrmions and revealed a\nsurprising plastic response at very short times, which may be relevant in\napplications based on the alignment of soft structures such as liquid crystal\nskyrmions."
    },
    {
        "anchor": "Efimov like phase of a three stranded DNA (Efimov-DNA) and the\n  renormalization group limit cycle: A three-stranded DNA with short range base pairings only is known to exhibit\na classical analog of the quantum Efimov effect, viz., a three chain bound\nstate at the two chain melting point where no two are bound. By using a\nnon-perturbative renormalization group method for a rigid duplex DNA and a\nflexible third strand, with base pairings and strand exchange, we show that the\nEfimov-DNA is associated with a limit cycle type behavior of the flow of an\neffective three chain interaction. The analysis also shows that thermally\ngenerated bubbles play an essential role in producing the effect. A toy model\nfor the flow equations shows the limit cycle in an extended three dimensional\nparameter space of the two-chain coupling and a complex three chain\ninteraction.",
        "positive": "Chiral stresses in nematic cell monolayers: Recent experiments on monolayers of spindle-like cells plated on adhesive\nstripe-shaped domains have provided a convincing demonstration that certain\ntypes of collective phenomena in epithelia are well described by active nematic\nhydrodynamics. While recovering some of the hallmark predictions of this\nframework, however, these experiments have also revealed a number of unexpected\nfeatures that could be ascribed to the existence of chirality over length\nscales larger than the typical size of a cell. In this article we elaborate on\nthe microscopic origin of chiral stresses in nematic cell monolayers and\ninvestigate how chirality affects the motion of topological defects, as well as\nthe collective motion in stripe-shaped domains. We find that chirality\nintroduces a characteristic asymmetry in the collective cellular flow, from\nwhich the ratio between chiral and non-chiral active stresses can be inferred\nby particle-image-velocimetry measurements. Furthermore, we find that chirality\nchanges the nature of the spontaneous flow transition under confinement and\nthat, for specific anchoring conditions, the latter has the structure of an\nimperfect pitchfork bifurcation."
    },
    {
        "anchor": "Nanoscale Liquid Crystal Lubrication Controlled by Surface Structure and\n  Film Composition: Liquid crystals have emerged as potential candidates for next-generation\nlubricants due to their tendency to exhibit long-range ordering. Here, we\nconstruct a full atomistic model of 4-cyano-4-hexylbiphenyl (6CB) nematic\nliquid crystal lubricants mixed with hexane and confined by mica surfaces. We\nexplore the effect of the surface structure of mica, as well as lubricant\ncomposition and thickness, on the nanoscale friction in the system. Our results\ndemonstrate the key role of the structure of the mica surfaces, specifically\nthe positions of potassium ($\\mathrm{K}^+$) ions, in determining the nature of\nsliding friction with monolayer lubricants, including the presence or absence\nof stick-slip dynamics. With the commensurate setup of confining surfaces, when\nthe grooves created between the periodic $\\mathrm{K}^+$ ions are parallel to\nthe sliding direction we observe a lower friction force as compared to the\nperpendicular situation. Random positions of ions exhibit even smaller friction\nforces with respect to the previous two cases. For thicker lubrication layers\nthe surface structure becomes less important and we observe a good agreement\nwith the experimental data on bulk viscosity of 6CB and the additive hexane. In\ncase of thicker lubrication layers, friction may still be controlled by tuning\nthe relative concentrations of 6CB and hexane in the mixture.",
        "positive": "Flow heterogeneities in supercooled liquids and glasses under shear: Using extensive non-equilibrium molecular dynamics simulations, we\ninvestigate a glassforming binary Lennard-Jones mixture under shear. Both\nsupercooled liquids and glasses are considered. Our focus is on the\ncharacterization of inhomogeneous flow patterns such as shear bands that appear\nas a transient response to the external shear. For the supercooled liquids, we\nanalyze the crossover from Newtonian to non-Newtonian behavior with increasing\nshear rate $\\dot{\\gamma}$. Above a critical shear rate $\\dot{\\gamma}_c$ where a\nnon-Newtonian response sets in, the transient dynamics are associated with the\noccurrence of short-lived vertical shear bands, i.e. bands of high mobility\nthat form perpendicular to the flow direction. In the glass states, long-lived\nhorizontal shear bands, i.e. bands of high mobility parallel to the flow\ndirection, are observed in addition to vertical ones. The systems with shear\nbands are characterized in terms of mobility maps, stress-strain relations,\nmean-squared displacements, and (local) potential energies. The initial\nformation of a horizontal shear band provides an efficient stress release,\ncorresponds to a local minimum of the potential energy, and is followed by a\nslow broadening of the band towards the homogeneously flowing fluid in the\nsteady-state. Whether a horizontal or a vertical shear band forms cannot be\npredicted from the initial undeformed sample. Furthermore, we show that with\nincreasing system size the probability for the occurrence of horizontal shear\nbands increases."
    },
    {
        "anchor": "The Breakdown of Kinetic Theory in Granular Shear Flows: We examine two basic assumptions of kinetic theory-- binary collisions and\nmolecular chaos-- using numerical simulations of sheared granular materials. We\ninvestigate a wide range of densities and restitution coefficients and\ndemonstrate that kinetic theory breaks down at large density and small\nrestitution coefficients. In the regimes where kinetic theory fails, there is\nan associated emergence of clusters of spatially correlated grains.",
        "positive": "Excitation spectra of a 3He impurity on 4He clusters: The diffusion Monte Carlo technique is used to calculate and analyze the\nexcitation spectrum of a single 3He atom bound to a cluster with N 4He atoms,\nwith the aim of establishing the most adequate filling ordering of\nsingle-fermion orbits to the mixed clusters with a large number of 3He atoms.\nThe resulting ordering looks like the rotational spectrum of a diatomic\nmolecule, being classified only by the angular momentum of the level, although\nvibrational-like excitations appear at higher energies for sufficiently large\nN."
    },
    {
        "anchor": "Image-based Analysis of Patterns Formed in Drying Drops: Image processing and pattern recognition offer a useful and versatile method\nfor optically characterizing drops of a colloidal solution during the drying\nprocess and in its final state. This paper exploits image processing techniques\napplied to cross-polarizing microscopy to probe birefringence and the\nbright-field microscopy to examine the morphological patterns. The\nbio-colloidal solution of interest is a mixture of water, liquid crystal (LC)\nand three different proteins [lysozyme (Lys), myoglobin (Myo), and bovine serum\nalbumin (BSA)], all at a fixed relative concentration. During the drying\nprocess, the LC phase separates and becomes optically active detectable through\nits birefringence. Further, as the protein concentrates, it forms cracks under\nstrain due to the evaporation of water. The mean intensity profile of the\ndrying process is examined using an automated image processing technique that\nreveals three unique regimes: a steady upsurge, a speedy rise, and an eventual\nsaturation. The high values of standard deviation show the complexity, the\nroughness, and inhomogeneity of the image surface. A semi-automated image\nprocessing technique is proposed to quantify the distance between the\nconsecutive cracks by converting those into high contrast images. The outcome\nof the image analysis correlates with the initial state of the mixture, the\nnature of the proteins, and the mechanical response of the final patterns. The\npaper reveals new insights on the self-assembly of the macromolecules during\nthe drying mechanism of any aqueous solution.",
        "positive": "Lessons of Slicing Membranes: Interplay of Packing, Free Area, and\n  Lateral Diffusion in Phospholipid/Cholesterol Bilayers: We employ 100 ns molecular dynamics simulations to study the influence of\ncholesterol on structural and dynamic properties of\ndipalmitoylphosphatidylcholine (DPPC) bilayers in the fluid phase. The effects\nof the cholesterol content on the bilayer structure are considered by varying\nthe cholesterol concentration between 0 and 50%. We concentrate on the free\narea in the membrane and investigate quantities that are likely to be affected\nby changes in the free area and free volume properties. It is found that\ncholesterol has a strong impact on the free area properties of the bilayer. The\nchanges in the amount of free area are shown to be intimately related to\nalterations in molecular packing, ordering of phospholipid tails, and\ncompressibility. Further, the behavior of the lateral diffusion of both DPPC\nand cholesterol molecules with an increasing amount of cholesterol can in part\nbe understood in terms of free area. Summarizing, our results highlight the\ncentral role of free area in comprehending the structural and dynamic\nproperties of membranes containing cholesterol."
    },
    {
        "anchor": "Heterogeneous relaxation dynamics in amorphous materials under cyclic\n  loading: Molecular dynamics simulations are performed to investigate heterogeneous\ndynamics in amorphous glassy materials under oscillatory shear strain. We\nconsider three-dimensional binary Lennard-Jones mixture well below the glass\ntransition temperature. The structural relaxation and dynamical heterogeneity\nare quantified by means of the self-overlap order parameter and the dynamic\nsusceptibility. We found that at sufficiently small strain amplitudes, the mean\nsquare displacement exhibits a broad sub-diffusive plateau and the system\nundergoes nearly reversible deformation over about $10^4$ cycles. Upon\nincreasing strain amplitude, the transition to the diffusive regime occurs at\nshorter time intervals and the relaxation process involves intermittent bursts\nof large particle displacements. The detailed analysis of particle hopping\ndynamics and the dynamic susceptibility indicates that mobile particles\naggregate into clusters whose sizes increase at larger strain amplitudes.\nFinally, the correlation between particle mobilities in consecutive time\nintervals demonstrates that dynamic facilitation becomes increasingly\npronounced at larger strain amplitudes.",
        "positive": "High yield, shell-stabilized, narrow-sized C3F8 nanobubbles with\n  different shell properties and precisely controllable response to acoustic\n  excitations: experimental observations and numerical simulations: Understanding the pressure dependence of the nonlinear behavior of\nultrasonically excited phospholipid (PL)-stabilized NBs is important for\noptimizing US exposure parameters for implementations of contrast enhanced\nultrasound, critical to molecular imaging. The viscoelastic properties of the\nshell can be controlled by introduction of membrane additives, such as\npropylene glycol as a membrane softener or glycerol as a membrane stiffener. We\nreport for the first time, the production of high yield NBs with narrow\ndispersity and different shell properties. Through precise control over size\nand shell structure, we show how these shell components interact with the\nphospholipid membrane, change its structure, affect their viscoelastic\nproperties, and consequently change their acoustic response. A two-photon\nmicroscopy technique through a polarity-sensitive fluorescent dye, C-laurdan,\nwas utilized to gain insights on the effect of membrane additives to the\nmembrane structure. We report how the shell stiffness of NBs affects the\npressure threshold (Pt) for the sudden amplification in the scattered acoustic\nsignal from NBs. For narrow size NBs with 200 nm mean size, we find Pt to be\nbetween 123-245 kPa for the NBs with the most flexible membrane as assessed\nusing C-Laurdan, 465-588 kPa for the NBs with intermediate stiffness and\n588-710 kPa for the NBs with stiff membranes. Numerical simulations of the NB\ndynamics are in good agreement with the experimental observations confirming\nthe dependence of acoustic response to shell properties, thereby substantiating\nfurther the development in engineering the shell of UCAs. The viscoelastic\ndependent threshold behavior can be utilized for significantly and selectively\nenhancing the diagnostic and therapeutic ultrasound applications of potent\nnarrow size NBs."
    },
    {
        "anchor": "Self-similar chain conformations in polymer gels: We use molecular dynamics simulations to study the swelling of randomly\nend-cross-linked polymer networks in good solvent conditions. We find that the\nequilibrium degree of swelling saturates at Q_eq = N_e**(3/5) for mean strand\nlengths N_s exceeding the melt entanglement length N_e. The internal structure\nof the network strands in the swollen state is characterized by a new exponent\nnu=0.72. Our findings are in contradiction to de Gennes' c*-theorem, which\npredicts Q_eq proportional N_s**(4/5) and nu=0.588. We present a simple Flory\nargument for a self-similar structure of mutually interpenetrating network\nstrands, which yields nu=7/10 and otherwise recovers the classical Flory-Rehner\ntheory. In particular, Q_eq = N_e**(3/5), if N_e is used as effective strand\nlength.",
        "positive": "Wrinkling of a thin film on a nematic liquid crystal elastomer: Wrinkles commonly develop in a thin film deposited on a soft elastomer\nsubstrate when the film is subject to compression. Motivated by recent\nexperiments [Agrawal et al., Soft Matter 8, 7138 (2012)] that show how wrinkle\nmorphology can be controlled by using a nematic elastomer substrate, we develop\nthe theory of small-amplitude wrinkles of an isotropic film atop a nematic\nelastomer. The directors of the nematic elastomer are assumed to lie in a plane\nparallel to the plane of the undeformed film. For uniaxial compression of the\nfilm along the direction perpendicular to the elastomer directors, the system\nbehaves as a compressed film on an isotropic substrate. When the uniaxial\ncompression is along the direction of nematic order, we find that the soft\nelasticity characteristic of liquid crystal elastomers leads to a critical\nstress for wrinkling which is very small compared to the case of an isotropic\nsubstrate. We also determine the wavelength of the wrinkles at the critical\nstress, and show how the critical stress and wavelength depend on substrate\ndepth and the anisotropy of the polymer chains in the nematic elastomer."
    },
    {
        "anchor": "Dynamics of a polymer in an active and crowded environment: We study the dynamics of an ideal polymer chain in a crowded, viscoelastic\nmedium and in the presence of active forces. The motion of the centre of mass\nand of individual monomers is calculated. On time scales that are comparable to\nthe persistence time of the active forces, monomers can move superdiffusively\nwhile on larger time scales subdiffusive behaviour occurs. The difference\nbetween this subdiffusion and that in absence of active forces is quantified.\nWe show that the polymer swells in response to active processes and determine\nhow this swelling depends on the viscoelastic properties of the environment.\nOur results are compared to recent experiments on the motion of chromosomal\nloci in bacteria.",
        "positive": "Device-spectroscopy of magnetic field effects in a polyfluorene organic\n  light-emitting diode: We perform charge-induced absorption and electroluminescence spectroscopy in\na polyfluorene organic magnetoresistive device. Our experiments allow us to\nmeasure the singlet exciton, triplet exciton and polaron densities in a live\ndevice under an applied magnetic field, and to distinguish between three\ndifferent models that were proposed to explain organic magnetoresistance. These\nmodels are based on different spin-dependent interactions, namely exciton\nformation, triplet exciton-polaron quenching and bipolaron formation. We show\nthat the singlet exciton, triplet exciton and polaron densities and\nconductivity all increase with increasing magnetic field. Our data are\ninconsistent with the exciton formation and triplet-exciton polaron quenching\nmodels."
    },
    {
        "anchor": "Detailed analysis of Rouse mode and dynamic scattering function of\n  highly entangled polymer melts in equilibrium: We present large-scale molecular dynamics simulations for a coarse-grained\nmodel of polymer melts in equilibrium. From detailed Rouse mode analysis we\nshow that the time-dependent relaxation of the autocorrelation function (ACF)\nof modes $p$ can be well described by the effective stretched exponential\nfunction due to the crossover from Rouse to reptation regime. The ACF is\nindependent of chain sizes $N$ for $N/p<N_e$ ($N_e$ is the entanglement\nlength), and there exists a minimum of the stretching exponent as $N/p\n\\rightarrow N_e$. As $N/p$ increases, we verify the crossover scaling behavior\nof the effective relaxation time $\\tau_{{\\rm eff},p}$ from the Rouse regime to\nthe reptation regime. We have also provided evidence that the incoherent\ndynamic scattering function follows the same crossover scaling behavior of the\nmean square displacement of monomers at the corresponding characteristic time\nscales. The decay of the coherent dynamic scattering function is slowed down\nand a plateau develops as chain sizes increase at the intermediate time and\nwave length scales. The tube diameter extracted from the coherent dynamic\nscattering function is equivalent to the previous estimate from the mean square\ndisplacement of monomers.",
        "positive": "A versatile and robust microfluidic device for capillary-sized simple or\n  multiple emulsions production: Ultrasound-vaporizable microdroplets can be exploited for targeted drug\ndelivery. However, it requires customized microfluidic techniques able to\nproduce monodisperse, capillary-sized and biocompatible multiple emulsions.\nRecent development of microfluidic devices led to the optimization of\nmicrodroplet production with high yields, low polydispersity and well-defined\ndiameters. So far, only few were shown to be efficient for simple droplets or\nmultiple emulsions production below 5 microns in diameter, which is required to\nprevent microembolism after intravenous injection. Here, we present a versatile\nmicrochip for both simple and multiple emulsion production. This parallelized\nsystem based on microchannel emulsification was designed to produce\nperfluorocarbon in water or water within perfluorocarbon in water emulsions\nwith capillary sizes (<5 $\\mu$m) and polydispersity index down to 5 % for in\nvivo applications such as spatiotemporally-triggered drug delivery using\nUltrasound. We show that droplet production at this scale is mainly controlled\nby interfacial tension forces, how capillary and viscosity ratios influence\ndroplet characteristics and how different production regimes may take place.\nThe better understanding of droplet formation and its relation to applied\npressures is supported by observations with a high-speed camera. Compared to\nprevious microchips, this device opens perspectives to produce injectable and\nbiocompatible droplets with a reasonable yield in order to realize preclinical\nstudies in mice."
    },
    {
        "anchor": "Curvature capillary repulsion: Directed assembly of colloids is an exciting field in materials science to\nform structures with new symmetries and responses. Fluid interfaces have been\nwidely exploited to make densely packed ordered structures. We have been\nstudying how interface curvature can be used in new ways to guide structure\nformation. On a fluid interface, the area of the deformation field around\nadsorbed microparticles depends on interface curvature; particles move to\nminimize the excess area of the distortions that they make in the interface.\nFor particles that are sufficiently small, this area decreases as particles\nmove along principle axes to sites of high deviatoric curvature. We have\nstudied this migration for microparticles on a curved host interface with zero\nmean curvature created by pinning an oil-water interface around a micropost.\nHere, on a similar interface, we demonstrate capillary curvature repulsion,\nthat is, we identify conditions in which microparticles migrate away from high\ncurvature sites. Using theory and experiment, we discuss the origin of these\ninteractions and their relationship to the particle's undulated contact line.\nWe discuss the implications of this new type of interaction in various contexts\nfrom materials science to microrobotics.",
        "positive": "On the formation of caveolae and similar membrane invaginations: We study a physical model for the formation of bud-like invaginations on\nfluid membranes under tension, and apply this model to caveolae formation. We\ndemonstrate that budding can be driven by membrane-bound inclusions (proteins)\nprovided that they exert asymmetric forces on the membrane that give rise to\nbending moments. In particular, Caveolae formation may not necessarily require\nforces to be applied by the cytoskeleton. Our theoretical model is able to\nexplain several features observed experimentally in caveolae, where proteins in\nthe caveolin family are known to play a crucial role in the formation of\ncaveolae buds. These include (i) the formation of caveolae buds with sizes in\nthe 100nm range (ii) that a fairly large variation of bud shape is expected\n(iii) that certain N and C termini deletion mutants result in vesicles that are\nan order of magnitude larger. Finally, we discuss the possible origin of the\nmorphological striations that are observed on the surfaces of the caveolae."
    },
    {
        "anchor": "In-silico modeling of early-stage biofilm formation: Several bacteria and bacteria strands form biofilms in different\nenvironmental conditions, e.g. pH, temperature, nutrients, etc. Biofilm growth,\ntherefore, is an extremely robust process. Because of this, while biofilm\ngrowth is a complex process affected by several variables, insights into\nbiofilm formation could be obtained studying simple schematic models. In this\nmanuscript, we describe a hybrid molecular dynamics and Monte Carlo model for\nthe simulation of the early stage formation of a biofilm, to explicitly\ndemonstrate that it is possible to account for most of the processes expected\nto be relevant. The simulations account for the growth and reproduction of the\nbacteria, for their interaction and motility, for the synthesis of\nextracellular polymeric substances and Psl trails. We describe the effect of\nthese processes on the early stage formation of biofilms, in two dimensions,\nand also discuss preliminary three-dimensional results.",
        "positive": "Viscoelasticity and Stokes-Einstein relation in repulsive and attractive\n  colloidal glasses: We report a numerical investigation of the visco-elastic behavior in models\nfor steric repulsive and short-range attractive colloidal suspensions, along\ndifferent paths in the attraction-strength vs packing fraction plane. More\nspecifically, we study the behavior of the viscosity (and its frequency\ndependence) on approaching the repulsive glass, the attractive glass and in the\nre-entrant region where viscosity shows a non monotonic behavior on increasing\nattraction strength. On approaching the glass lines, the increase of the\nviscosity is consistent with a power-law divergence with the same exponent and\ncritical packing fraction previously obtained for the divergence of the density\nfluctuations. Based on mode-coupling calculations, we associate the increase of\nthe viscosity with specific contributions from different length scales. We also\nshow that the results are independent on the microscopic dynamics by comparing\nnewtonian and brownian simulations for the same model. Finally we evaluate the\nStokes-Einstein relation approaching both glass transitions, finding a clear\nbreakdown which is particularly strong for the case of the attractive glass."
    },
    {
        "anchor": "Evaporation of dilute sodium dodecyl sulfate droplets on a hydrophobic\n  substrate: Evaporation of surfactant laden sessile droplets is omnipresent in nature and\nindustrial applications such as inkjet printing. Soluble surfactants start to\nform micelles in an aqueous solution for surfactant concentrations exceeding\nthe critical micelle concentration (CMC). Here, the evaporation of aqueous\nsodium dodecyl sulfate (SDS) sessile droplets on hydrophobic surfaces were\nexperimentally investigated for SDS concentrations ranging from 0.025 to 1 CMC.\nIn contrast to the constant contact angle of an evaporating sessile water\ndroplet, we observed that, at the same surface the contact angle of an SDS\nladen droplet with a concentration below 0.5 CMC first decreases, then\nincreases, and finally decreases resulting in a local contact angle minimum.\nSurprisingly, the minimum contact angle was found to be substantially lower\nthan the static receding contact angle and it decreased with decreasing initial\nSDS concentration. Furthermore, the bulk SDS concentration at the local contact\nangle minimum was found to decrease with a decrease in the initial SDS\nconcentration. The location of the observed contact angle minimum relative to\nthe normalized evaporation time and its minimum value proved to be independent\nof both the relative humidity and the droplet volume and thus, of the total\nevaporation time. We discuss the observed contact angle dynamics in terms of\nthe formation of a disordered layer of SDS molecules on the substrate at\nconcentrations below 0.5 CMC. The present work underlines the complexity of the\nevaporation of sessile liquid-surfactant droplets and the influence of\nsurfactant-substrate interactions on the evaporation process.",
        "positive": "Percolation with trapping mechanism drives active gels to the critically\n  connected state: Cell motility and tissue morphogenesis depend crucially on the dynamic\nremodelling of actomyosin networks. An actomyosin network consists of an actin\npolymer network connected by crosslinker proteins and motor protein myosins\nthat generate internal stresses on the network. A recent discovery shows that\nfor a range of experimental parameters, actomyosin networks contract to\nclusters with a power-law size distribution [Alvarado J. et al. (2013) Nature\nPhysics 9 591]. Here, we argue that actomyosin networks can exhibit robust\ncritical signature without fine-tuning because the dynamics of the system can\nbe mapped onto a modified version of percolation with trapping (PT), which is\nknown to show critical behaviour belonging to the static percolation\nuniversality class without the need of fine-tuning of a control parameter. We\nfurther employ our PT model to generate experimentally testable predictions."
    },
    {
        "anchor": "Surface Tensions between Active Fluids and Solid Interfaces: bare vs\n  dressed: We analyze the surface tension exerted at the interface between an active\nfluid and a solid boundary in terms of tangential forces. Focusing on active\nsystems known to possess an equation of state for the pressure, we show that\ninterfacial forces are of a more complex nature. Using a number of macroscopic\nsetups, we show that the surface tension is a combination of an\nequation-of-state abiding part and of setup-dependent contributions. The latter\narise from generic setup-dependent steady currents which \"dress\" the\nmeasurement of the \"bare\" surface tension. The former shares interesting\nproperties with its equilibrium counterpart, and can be used to generalize the\nYoung-Laplace law to active systems. We finally show how a suitably designed\nprobe can directly access this bare surface tensions, which can also be\ncomputed using a generalized Virial formula.",
        "positive": "Sedimentation of binary mixtures of like- and oppositely charged\n  colloids: the primitive model or effective pair potentials?: We study sedimentation equilibrium of low-salt suspensions of binary mixtures\nof charged colloids, both by Monte Carlo simulations of an effective\ncolloids-only system and by Poisson-Boltzmann theory of a colloid-ion mixture.\nWe show that the theoretically predicted lifting and layering effect, which\ninvolves the entropy of the screening ions and a spontaneous macroscopic\nelectric field [J. Zwanikken and R. van Roij, Europhys. Lett. {\\bf 71}, 480\n(2005)], can also be understood on the basis of an effective colloid-only\nsystem with pairwise screened-Coulomb interactions. We consider, by theory and\nby simulation, both repelling like-charged colloids and attracting oppositely\ncharged colloids, and we find a re-entrant lifting and layering phenomenon when\nthe charge ratio of the colloids varies from large positive through zero to\nlarge negative values."
    },
    {
        "anchor": "The effect of premature wall yield on creep testing of\n  strongly-flocculated suspensions: Measuring yielding in cohesive suspensions is often hampered by slip at\nmeasurement surfaces. This paper presents creep data for strongly-flocculated\nsuspensions obtained using vane-in-cup tools with differing cup-to-vane\ndiameter ratios. The three suspensions were titania and alumina aggregated at\ntheir isoelectric points and polymer-flocculated alumina. The aim was to find\nthe diameter ratio where slip or premature yielding at the cup wall had no\neffect on the transient behaviour. The large diameter ratio results showed\nreadily understandable material behaviour comprising linear viscoelasticity at\nlow stresses, strain-softening close to yielding, time-dependent yield across a\nrange of stresses and then viscous flow. Tests in small ratio geometries\nhowever showed more complex responses. Effects attributed to the cup wall\nincluded delayed softening, slip, multiple yielding and stick-slip events, and\nunsteady flow. The conclusion was that cups have to be relatively large to\neliminate wall artefacts. A diameter ratio of three was sufficient in practice,\nalthough the minimum ratio must be material dependent.",
        "positive": "Ribbon polymers in poor solvents: layering transitions in annular and\n  tubular condensates: We study the structures of a ribbon or ladder polymer immersed in poor\nsolvents. The anisotropic bending rigidity coupled with the surface tension\nleads ribbon polymers to spontaneous formation of highly anisotropic\ncondensates in poor solvents. Unlike ordinary flexible polymers these\ncondensates undergo a number of distinct layering transitions as a function of\nchain length or solvent quality, and the size of condensates becomes\nnon-monotonic function of chain length. We show that the fluctuations of the\ncondensates are in general small and these condensates are stable."
    },
    {
        "anchor": "Thermodynamic control and dynamical regimes in protein folding: Monte Carlo simulations of a simple lattice model of protein folding show two\ndistinct regimes depending on the chain length. The first regime well describes\nthe folding of small protein sequences and its kinetic counterpart appears to\nbe single exponential in nature, while the second regime is typical of\nsequences longer than 80 amino acids and the folding performance achievable is\nsensitive to target conformation. The extent to which stability, as measured by\nthe energy of a sequence in the target, is an essential requirement and affects\nthe folding dynamics of protein molecules in the first regime is investigated.\nThe folding dynamics of sequences whose design stage was restricted to a\ncertain fraction of randomly selected amino acids shows that while some degree\nof stability is a necessary and sufficient condition for successful folding,\ndesigning sequences that provide the lowest energy in the target seems to be a\nsuperfluous constraint. By studying the dynamics of under annealed but\notherwise freely designed sequences we explore the relation between stability\nand kinetic accessibility. We find that there is no one-to-one correspondence\nbetween having low energy and folding quickly to the target, as only a small\nfraction of the most stable sequences were also found to fold relatively\nquickly.",
        "positive": "Dynamical properties of heterogeneous nucleation of parallel hard\n  squares: We use the Dynamic Density-Functional Formalism and the Fundamental Measure\nTheory as applied to a fluid of parallel hard squares to study the dynamics of\nheterogeneous growth of non-uniform phases with columnar and crystalline\nsymmetries. The hard squares are (i) confined between soft repulsive walls with\nsquare symmetry, or (ii) exposed to external potentials that mimic the presence\nof obstacles with circular, square, rectangular or triangular symmetries. For\nthe first case the final equilibrium profile of a well commensurated cavity\nconsists of a crystal phase with highly localized particles in concentric\nsquare layers at the nodes of a slightly deformed square lattice. We\ncharacterize the growth dynamics of the crystal phase by quantifying the\ninterlayer and intralayer fluxes and the non-monotonicity of the former, the\nsaturation time, and other dynamical quantities. The interlayer fluxes are much\nmore monotonic in time, and dominant for poorly commensurated cavities, while\nthe opposite is true for well commensurated cells: although smaller, the time\nevolution of interlayer fluxes are much more complex, presenting strongly\ndamped oscillations which dramatically increase the saturation time. We also\nstudy how the geometry of the obstacle affects the symmetry of the final\nequilibrium non-uniform phase (columnar vs. crystal). For obstacles with\nfourfold symmetry, (circular and square) the crystal is more stable, while the\ncolumnar phase is stabilized for obstacles without this symmetry (rectangular\nor triangular). We find that, in general, density waves of columnar symmetry\ngrow from the obstacle. However, additional particle localization along the\nwavefronts gives rise to a crystalline structure which is conserved for\ncircular and square obstacles, but destroyed for the other two obstacles where\ncolumnar symmetry is restored."
    },
    {
        "anchor": "Machine learning understands knotted polymers: Simulated configurations of flexible knotted rings confined inside a\nspherical cavity are fed into long-short term memory neural networks (LSTM NNs)\ndesigned to distinguish knot types. The results show that they perform well in\nknot recognition even if tested against flexible, strongly confined and\ntherefore highly geometrically entangled rings. In agreement with the\nexpectation that knots are delocalized in dense polymers, a suitable\ncoarse-graining procedure on configurations boosts the performance of the LSTMs\nwhen knot identification is applied to rings much longer than those used for\ntraining. Notably, when the NNs fail, usually the wrong prediction still\nbelongs to the same topological family of the correct one. The fact that the\nLSTMs are able to grasp some basic properties of the ring's topology is\ncorroborated by a test on knot types not used for training. We also show that\nthe choice of the NN architecture is important: simpler convolutional NNs do\nnot perform so well. Finally, all results depend on the features used for\ninput: surprisingly, coordinates or bond directions of the configurations\nprovide the best accuracy to the NNs, even if they are not invariant under\nrotations (while the knot type is invariant). Other rotational invariant\nfeatures we tested are based on distances, angles, and dihedral angles.",
        "positive": "MRI Investigations of Particle Motion within a Three-Dimensional\n  Vibro-Fluidized Granular Bed: The unique ability of magnetic resonance imaging (MRI) to provide spatial and\ntemporal information from optically opaque systems, in three dimensions, make\nit an ideal tool to study the internal motion of rapid granular flows. This\npaper will focus on the use of ultra-fast velocity compensated MRI measurements\nto study particle velocity and density distributions in a granular gas,\nproduced by vibrating vertically a bed of mustard seeds at 40 Hz. Specifically,\na velocity compensated, double spin-echo, triggered, one-dimensional MRI\nprofiling pulse sequence was developed. This gives an MRI temporal resolution\nof approximately 2 ms and also minimises MRI velocity artefacts. 12 phase\nmeasurements per vibration cycle were used. The data can be used to extract\nvalues of the mustard seed average velocity and velocity propagators\n(probability distributions functions) as a function of the phase of the\nvibration cycle and vertical height within the cell. The data show strong\ntransient effects during the impact phase of the vibration. A detailed\ndiscussion of the temporal passage of the individual phase resolved, height\nresolved velocity distributions, along with seed velocity propagators at a fix\nheight from the vibrating base is presented."
    },
    {
        "anchor": "Swinging and Synchronized Rotations of Red Blood Cells in Simple Shear\n  Flow: The dynamics of red blood cells (RBCs) in simple shear flow was studied using\na theoretical approach based on three variables: a shape parameter, the\ninclination angle $\\theta$, and phase angle $\\phi$ of the membrane rotation. At\nhigh shear rate and low viscosity contrast of internal fluid, RBCs exhibit\ntank-treading motion, where $\\phi$ rotates with swinging oscillation of shape\nand $\\theta$. At low shear rate, tumbling motion occurs and $\\theta$ rotates.\nIn the middle region between these two phases, it is found that synchronized\nrotation of $\\phi$ and $\\theta$ with integer ratios of the frequencies occurs\nin addition to intermittent rotation. These dynamics are robust to the\nmodification of the potential of the RBC shape and membrane rotation.\n  Our results agree well with recent experiments.",
        "positive": "Olfactory receptors for a smell sensor: A comparative study of the\n  electrical responses of rat I7 and human 17-40: In this paper we explore relevant electrical properties of two olfactory\nreceptors (ORs), one from rat OR I7 and the other from human OR 17-40, which\nare of interest for the realization of smell nanobiosensors. The investigation\ncompares existing experiments, coming from electrochemical impedance\nspectroscopy, with the theoretical expectations obtained from an impedance\nnetwork protein analogue, recently developed. The changes in the response due\nto the sensing action of the proteins are correlated with the conformational\nchange undergone by the single protein. The satisfactory agreement between\ntheory and experiments points to a promising development of a new class of\nnanobiosensors based on the electrical properties of sensing proteins."
    },
    {
        "anchor": "Average negative heat in a non-Markovian bath: We experimentally study the motion of a colloidal particle, translated back\nand forth within a viscoelastic, i.e. non-Markovian bath. The particle starts\nin equilibrium before the forward motion, but only partially relaxes at the\nturning point. During the backward motion, we measure a systematic (negative)\nheat flow from the bath to the particle. Our observations are in good agreement\nwith a simple model that describes the time-delayed response of the fluid. We\nexpect our results to be important for the realization and optimization of\nnovel types of micro-engines in non-Markovian surroundings.",
        "positive": "Dynamical Diagram and Scaling in Polymer Driven Translocation: By analyzing the real space nonequilibrium dynamics of polymers, we elucidate\nthe physics of driven translocation and propose its dynamical scaling scenario\nanalogous to that in the surface growth phenomena. We provide a detailed\naccount of the previously proposed tension-propagation formulation and extend\nit to cover the broader parameter space relevant to real experiments; In\naddition to a near-equilibrium regime, we identify three distinct\nnonequilibrium regimes reflecting the steady-state property of a dragged\npolymer with the finite extensibility. Finite size effects are also pointed\nout. These elements are shown to be crucial for the appropriate comparison with\nexperiments and simulations."
    },
    {
        "anchor": "Transient fluctuation-induced forces in driven electrolytes after an\n  electric field quench: Understanding how electrolyte solutions behave out of thermal equilibrium is\na long-standing endeavor in many areas of chemistry and biology. Although\nmean-field theories are widely used to model the dynamics of electrolytes, it\nis also important to characterize the effects of fluctuations in these systems.\nIn a previous work, we showed that the dynamics of the ions in a strong\nelectrolyte that is driven by an external electric field can generate\nlong-ranged correlations manifestly different from the equilibrium screened\ncorrelations; in the nonequilibrium steady state, these correlations give rise\nto a novel long-range fluctuation-induced force (FIF). Here, we extend these\nresults by considering the dynamics of the strong electrolyte after it is\nquenched from thermal equilibrium upon the application of a constant electric\nfield. We show that the asymptotic long-distance limit of both charge and\ndensity correlations is generally diffusive in time. These correlations give\nrise to long-ranged FIFs acting on the neutral confining plates with long-time\nregimes that are governed by power-law temporal decays toward the steady-state\nvalue of the force amplitude. These findings show that nonequilibrium\nfluctuations have nontrivial implications on the dynamics of objects immersed\nin a driven electrolyte, and they could be useful for exploring new ways of\ncontrolling long-distance forces in charged solutions.",
        "positive": "Actomyosin contraction induces droplet motility: While cell crawling on a solid surface is relatively well understood, and\nrelies on substrate adhesion, some cells can also swim in the bulk, through\nmechanisms that are still largely unclear. Here, we propose a minimal model for\nin-bulk self-motility of a droplet containing an isotropic and compressible\ncontractile gel, representing a cell extract containing a disordered actomyosin\nnetwork. In our model, contraction mediates a feedback loop between\nmyosin-induced flow and advection-induced myosin accumulation, which leads to\nclustering and a locally enhanced flow. Interactions of the emerging clusters\nwith the droplet membrane break flow symmetry and set the whole droplet into\nmotion. Depending mainly on the balance between contraction and diffusion, this\nmotion can be either straight or circular. Our simulations and analytical\nresults provide a framework allowing to study in-bulk myosin-driven cell\nmotility in living cells and to design synthetic motile active matter droplets."
    },
    {
        "anchor": "Two-dimensional lattice-fluid model with water-like anomalies: We investigate a lattice-fluid model defined on a two-dimensional triangular\nlattice, with the aim of reproducing qualitatively some anomalous properties of\nwater. Model molecules are of the \"Mercedes Benz\" type, i.e., they possess a D3\n(equilateral triangle) symmetry, with three bonding arms. Bond formation\ndepends both on orientation and local density. We work out phase diagrams,\nresponse functions, and stability limits for the liquid phase, making use of a\ngeneralized first order approximation on a triangle cluster, whose accuracy is\nverified, in some cases, by Monte Carlo simulations. The phase diagram displays\none ordered (solid) phase which is less dense than the liquid one. At fixed\npressure the liquid phase response functions show the typical anomalous\nbehavior observed in liquid water, while, in the supercooled region, a\nreentrant spinodal is observed.",
        "positive": "Large deformation and instability of soft hollow cylinder with surface\n  effects: Surface stress, which is always neglected in classical elastic theories, has\nrecently emerged as a key role in the mechanics of highly deformable soft\nsolids. In this paper, the effect of surface stress on the deformation and\ninstability of soft hollow cylinder are analyzed. By incorporating surface\nenergy density function into the constitutive model of a hyper-elastic theory,\nexplicit solutions are obtained for the deformation of soft hollow cylinder\nunder the conditions of uniform pressure loading and geometric everting. It is\nfound that surface tension evidently alters the deformation of the soft\ncylinder. Specifically, the surface stiffness resists the deformation, but the\nresidual surface stress is inclined to larger deformation. Effects of surface\nstress on the instability of the soft hollow cylinder is also explored. For\nboth the pressure loading and geometric everting conditions, significant\nchanges in critical condition of the creases are found by varying the surface\nparameter. The results in this work reveal that surface energy obviously\ninfluences both the deformation and the instability of soft hollow cylinder at\nfinite deformation. The obtained results will be helpful for understanding and\npredicting the mechanical behavior of soft structures accurately."
    },
    {
        "anchor": "Feedback Microrheology in Soft Matter: Soft matter consists of meso-scale (nm~{\\mu}m) structures that are formed by\nweak interactions and reorganized under thermal fluctuations. The resulting\ncomplex relaxation phenomena may be probed with microrheology, by observing the\nmovement of embedded probe particles. Because of the softness of the material,\nhowever, perturbations to the probe that are inevitably added during\nmicrorheology experiments prevent direct translation of those movements to\nrheological properties. In this study, we conducted optical-trap-based\nmicrorheology with significantly reduced mechanical perturbations; dual\nfeedback technology allowed us to apply well-determined optical-trapping forces\nto a fluctuating embedded probe and precisely measure its response and\nfluctuations with high spatiotemporal resolution. We demonstrate the improved\nperformance of this technique by studying an reconstituted network of actin\ncytoskeletal filaments, observing their slow dynamics, homogeneous thermal\nfluctuations as well as activated hopping between mesoscale microenvironments.",
        "positive": "Unraveling the Role of Frictional Contacts and Particle Orientational\n  Order During Shear-thickening in Suspensions of Colloidal Rods: There is now convincing evidence that inter-particle frictional contacts are\nessential for observing shear-thickening in concentrated suspensions of compact\nparticles. While this has inspired many strategies to tailor the rheology in\nthese systems, in the more general case, viz-a-viz suspensions of anisotropic\nparticles, the mechanism of shear-thickening remains unclear. Here through\nsimultaneous measurements of the bulk viscosity and the first Normal stress\ndifference, we show that strong shear thickening in suspensions of colloidal\nrods is accompanied by large positive normal stresses, indicating the formation\nof a system-spanning frictional contact network. We also find that flow in the\nshear-thickening regime is unsteady and shows a rather rich time-dependence. By\ncarrying out single particle-resolved confocal rheology measurements, we\nprovide compelling evidence that this rheological chaos arises from a strong\ncoupling between the imposed flow and particle orientational order. Building on\nthese observations, we designed colloidal rods with temperature-tunable\ntribological properties and demonstrate the feasibility of achieving in-situ\ncontrol over suspension rheology. These findings show that the interplay\nbetween orientational order and frictional interactions plays a critical role\nin the shear thickening of dense suspensions of colloidal rods."
    },
    {
        "anchor": "Hydrodynamic effects in driven soft matter: Recent theoretical works exploring the hydrodynamics of soft material in\nnon-equilibrium situations are reviewed. We discuss the role of hydrodynamic\ninteractions for three different systems: i) the deformation and orientation of\nsedimenting semiflexible polymers, ii) the propulsion and force-rectification\nwith a nano-machine realized by a rotating elastic rod, and iii) the\ndeformation of a brush made of grafted semiflexible polymers in shear flows. In\nall these examples deformable polymers are subject to various hydrodynamic\nflows and hydrodynamic interactions. Perfect stiff nano-cylinders are known to\nshow no orientational effects as they sediment through a viscous fluid, but it\nis the coupling between elasticity and hydrodynamic torques that leads to an\norientation perpendicular to the direction of sedimentation. Likewise, a\nrotating stiff rod does not lead to a net propulsion in the Stokes limit, but\nif bending is allowed an effective thrust develops whose strength and direction\nis independent of the sense of rotation and thus acts as a rectification\ndevice. Lastly, surface-anchored polymers are deformed by shear flows, which\nmodifies the effective hydrodynamic boundary condition in a non-linear fashion.\nAll these results are obtained with hydrodynamic Brownian dynamics simulation\ntechniques, as appropriate for dilute systems. Scaling analyses are presented\nwhen possible. The common theme is the interaction between elasticity of soft\nmatter and hydrodynamics, which can lead to qualitatively new effects.",
        "positive": "Generic folding and transition hierarchies for surface adsorption of\n  hydrophobic-polar lattice model proteins: The thermodynamic behavior and structural properties of hydrophobic-polar\n(HP) lattice proteins interacting with attractive surfaces are studied by means\nof Wang-Landau sampling. Three benchmark HP sequences (48mer, 67mer, and\n103mer) are considered with different types of surfaces, each of which attract\neither all monomers, only hydrophobic (H) monomers, or only polar (P) monomers,\nrespectively. The diversity of folding behavior in dependence of surface\nstrength is discussed. Analyzing the combined patterns of various structural\nobservables, such as, e.g., the derivatives of the numbers of surface contacts,\ntogether with the specific heat, we are able to identify generic categories of\nfolding and transition hierarchies. We also infer a connection between these\ntransition categories and the relative surface strengths, i.e., the ratio of\nthe surface attractive strength to the interchain attraction among H monomers.\nThe validity of our proposed classification scheme is reinforced by the\nanalysis of additional benchmark sequences. We thus believe that the folding\nhierarchies and identification scheme are generic for HP proteins interacting\nwith attractive surfaces, regardless of chain length, sequence, or surface\nattraction."
    },
    {
        "anchor": "Geometrically-controlled twist transitions in nematic cells: We study geometrically-controlled twist transitions of a nematic confined\nbetween a sinusoidal grating and a flat substrate. In these cells the\ntransition to the twisted state is driven by surface effects. We have\nidentified the mechanisms responsible for the transition analytically and used\nexact numerical calculations to study the range of surface parameters where the\ntwist instability occurs. Close to these values the cell operates under minimal\nexternal fields or temperature variations.",
        "positive": "Antipolar ordering of topological defects in active liquid crystals: ATP-driven microtubule-kinesin bundles can self-assemble into two-dimensional\nactive liquid crystals (ALCs) that exhibit a rich creation and annihilation\ndynamics of topological defects, reminiscent of particle-pair production\nprocesses in quantum systems. This recent discovery has sparked considerable\ninterest but a quantitative theoretical description is still lacking. We\npresent and validate a minimal continuum theory for this new class of active\nmatter systems by generalizing the classical Landau-de Gennes free-energy to\naccount for the experimentally observed spontaneous buckling of motor-driven\nextensile microtubule bundles. The resulting model agrees with recently\npublished data and predicts a regime of antipolar order. Our analysis implies\nthat ALCs are governed by the same generic ordering principles that determine\nthe non-equilibrium dynamics of dense bacterial suspensions and elastic bilayer\nmaterials. Moreover, the theory manifests an energetic analogy with strongly\ninteracting quantum gases. Generally, our results suggest that complex\nnon-equilibrium pattern-formation phenomena might be predictable from a few\nfundamental symmetry-breaking and scale-selection principles."
    },
    {
        "anchor": "Multiple Types of Aging in Active Glass: Recent experiments and simulations have revealed glassy features in the\ncytoplasm, living tissues as well as dense assemblies of self propelled\ncolloids. This leads to a fundamental question: how do these non-equilibrium\n(active) amorphous materials differ from conventional passive glasses, created\neither by lowering temperature or by increasing density? To address this we\ninvestigate the aging behaviour after a quench to an almost arrested state of a\nmodel active glass former, a Kob-Andersen glass in two dimensions. Each\nconstituent particle is driven by a constant propulsion force whose direction\ndiffuses over time. Using extensive molecular dynamics simulations we reveal\nrich aging behaviour of this dense active matter system: short persistence\ntimes of the active forcing lead to effective thermal aging; in the opposite\nlimit we find a two-step aging process with active athermal aging at short\ntimes followed by activity-driven aging at late times. We develop a dedicated\nsimulation method that gives access to this long-time scaling regime for highly\npersistent active forces.",
        "positive": "The Geometry of Soft Materials: A Primer: We present an overview of the differential geometry of curves and surfaces\nusing examples from soft matter as illustrations. The presentation requires a\nbackground only in vector calculus and is otherwise self-contained."
    },
    {
        "anchor": "Equilibrium and out of equilibrium thermodynamics in supercooled liquids\n  and glasses: We review the inherent structure thermodynamical formalism and the\nformulation of an equation of state for liquids in equilibrium based on the\n(volume) derivatives of the statistical properties of the potential energy\nsurface. We also show that, under the hypothesis that during aging the system\nexplores states associated to equilibrium configurations, it is possible to\ngeneralize the proposed equation of state to out-of-equilibrium conditions. The\nproposed formulation is based on the introduction of one additional parameter\nwhich, in the chosen thermodynamic formalism, can be chosen as the local minima\nwhere the slowly relaxing out-of-equilibrium liquid is trapped.",
        "positive": "Spontaneous chiralization of polar active colloids: Polar active particles constitute a wide class of synthetic colloids that are\nable to propel along a preferential direction, given by their polar axis. Here,\nwe demonstrate a generic self-phoretic mechanism that leads to their\nspontaneous chiralization through a symmetry breaking instability. We find that\nthe transition of an active particle from a polar to a chiral symmetry is\ncharacterized by the emergence of active rotation and of circular trajectories.\nWe show that the instability is driven by the advection of a solute that\ninteracts differently with the two portions of the particle surface and it\noccurs through a supercritical pitchfork bifurcation."
    },
    {
        "anchor": "Pore-scale Modelling of Gravity-driven Drainage in Disordered Porous\n  Media: Multiphase flow through a porous medium involves complex interactions between\ngravity, wettability and capillarity during drainage process. In contrast to\nthese factors, the effect of pore distribution on liquid retention is less\nunderstood. In particular, the quantitative correlation between the fluid\ndisplacement and level of disorder has not yet been established. In this work,\nwe employ direct numerical simulation by solving the Navier-Stokes equations\nand using volume of fluid method to track the liquid-liquid interface during\ndrainage in disordered porous media. The disorder of pore configuration is\ncharacterized by an improved index to capture small microstructural\nperturbation, which is pivotal for fluid displacement in porous media. Then, we\nfocus on the residual volume and morphological characteristics of saturated\nzones after drainage and compare the effect of disorder under different\nwettability (i.e., the contact angle) and gravity (characterized by a modified\nBond number) conditions. Pore-scale simulations reveal that the\nhighly-disordered porous medium is favourable to improve liquid retention and\nprovide various morphologies of entrapped saturated zones. Furthermore, the\ndisorder index has a positive correlation to the characteristic curve index (n)\nin van Genuchten equation, controlling the shape of the retention\ncharacteristic curves. It is expected that the findings will benefit to a broad\nrange of industrial applications involving drainage processes in porous media,\ne.g., drying, carbon sequestration, and underground water remediation.",
        "positive": "Dynamic density functional theory for drying colloidal suspensions:\n  Comparison of hard-sphere free-energy functionals: Dynamic density functional theory (DDFT) is a promising approach for\npredicting the structural evolution of a drying suspension containing one or\nmore types of colloidal particles. The assumed free-energy functional is a key\ncomponent of DDFT that dictates the thermodynamics of the model and, in turn,\nthe density flux due to a concentration gradient. In this work, we compare\nseveral commonly used free-energy functionals for drying hard-sphere\nsuspensions including local-density approximations based on the ideal-gas,\nvirial, and Boubl\\'{i}k-Mansoori-Carnahan-Starling-Leland (BMCSL) equations of\nstate as well as a weighted-density approximation based on fundamental measure\ntheory (FMT). To determine the accuracy of each functional, we model one- and\ntwo-component hard-sphere suspensions in a drying film with varied initial\nheights and compositions, and we compare the DDFT-predicted volume-fraction\nprofiles to particle-based Brownian dynamics (BD) simulations. FMT accurately\npredicts the structure of the one-component suspensions even at high\nconcentrations and when significant density gradients develop, but the virial\nand BMCSL equations of state provide reasonable approximations for smaller\nconcentrations at a reduced computational cost. In the two-component\nsuspensions, FMT and BMCSL are similar to each other but modestly overpredict\nthe extent of stratification by size compared to BD simulations. This work\nprovides helpful guidance for selecting thermodynamic models for soft materials\nin nonequilibrium processes such as solvent drying, solvent freezing, and\nsedimentation."
    },
    {
        "anchor": "The steady state partial slip problem for half plane contacts subject to\n  a constant normal load using glide dislocations: A new solution for general half-plane contact problems subject to a constant\nnormal load together with alternating shear loads and tension in the steady\nstate is presented. The method uses a formulation where a displacement\ncorrection is made to the fully stuck contact solution. There will be two outer\nregions of slip and a central permanent stick zone, which is explicitly\nestablished. Thereby, the maximum extent of the slip zones is effectively\nspecified. Cases of small and large tension are studied, that is when the\ndirection of slip is the same or opposing at the ends of the contact,\nrespectively.",
        "positive": "An effective long-range attraction between protein molecules in\n  solutions studied by small angle neutron scattering: Small angle neutron scattering intensity distributions taken from cytochrome\nC and lysozyme protein solutions show a rising intensity at very small wave\nvector, Q, which can be interpreted in terms of the presence of a weak\nlong-range attraction between protein molecules. This interaction has a range\nseveral times that of the diameter of the protein molecule, much greater than\nthe range of the screened electrostatic repulsion. We show evidence that this\nlong-range attraction is closely related to the type of anion present and ion\nconcentration in the solution."
    },
    {
        "anchor": "The interplay between activity and filament flexibility determines the\n  emergent properties of active nematics: Active nematics are microscopically driven liquid crystals that exhibit\ndynamical steady states characterized by the creation and annihilation of\ntopological defects. Motivated by experimental realizations of such systems\nmade of biopolymer filaments and motor proteins, we describe a large-scale\nsimulation study of a particle-based computational model that explicitly\nincorporates the semiflexibility of the biopolymers. We find that energy\ninjected into the system at the particle scale preferentially excites bend\ndeformations, renormalizing the filament bend modulus to smaller values. The\nemergent characteristics of the active nematic depend on activity and\nflexibility only through this activity-renormalized bend modulus, demonstrating\nthat material parameters such as the Frank `constants' must explicitly depend\non activity in a continuum hydrodynamic description of an active nematic.\nFurther, we present a systematic way to estimate these material parameters from\nobservations of deformation fields and defect shapes in experimental or\nsimulation data.",
        "positive": "Deformation and flow of a two-dimensional foam under continuous shear: We investigate the flow properties of a two-dimensional aqueous foam\nsubmitted to a quasistatic shear in a Couette geometry. A strong localization\nof the flow (shear banding) at the edge of the moving wall is evidenced,\ncharacterized by an exponential decay of the average tangential velocity.\nMoreover, the analysis of the rapid velocity fluctuations reveals self-similar\ndynamical structures consisting of clusters of bubbles rolling as rigid bodies.\nTo relate the instantaneous (elastic) and time-averaged (plastic) components of\nthe strain, we develop a stochastic model where irreversible rearrangements are\nactivated by local stress fluctuations originating from the rubbing of the\nwall. This model gives a complete description of our observations and is also\nconsistent with data obtained on granular shear bands by other groups."
    },
    {
        "anchor": "Diffusing-wave spectroscopy of nonergodic media: We introduce an elegant method which allows the application of diffusing-wave\nspectroscopy (DWS) to nonergodic, solid-like samples. The method is based on\nthe idea that light transmitted through a sandwich of two turbid cells can be\nconsidered ergodic even though only the second cell is ergodic. If absorption\nand/or leakage of light take place at the interface between the cells, we\nestablish a so-called \"multiplication rule\", which relates the intensity\nautocorrelation function of light transmitted through the double-cell sandwich\nto the autocorrelation functions of individual cells by a simple\nmultiplication. To test the proposed method, we perform a series of DWS\nexperiments using colloidal gels as model nonergodic media. Our experimental\ndata are consistent with the theoretical predictions, allowing quantitative\ncharacterization of nonergodic media and demonstrating the validity of the\nproposed technique.",
        "positive": "Impact of size effects on photopolymerization and its optical monitoring\n  in-situ: Photopolymerization processes are exploited in light exposure-based 3D\nprinting technologies, where either a focused laser beam or a patterned light\nsheet allows layers of a UV curable, liquid pre-polymer to be solidified. Here\nwe focus on the crucial, though often neglected, role of the layer thickness on\nphotopolymerization. The temporal evolution of polymerization reactions\noccurring in droplets of acrylate-based oligomers and in photoresist films with\nvaried thickness is investigated by means of an optical system, which is\nspecifically designed for in-situ and real-time monitoring. The time needed for\ncomplete curing is found to increase as the polymerization volume is decreased\nbelow a characteristic threshold that depends on the specific reaction pathway.\nThis behavior is rationalized by modelling the process through a size-dependent\npolymerization rate. Our study highlights that the formation of\nphotopolymerized networks might be affected by the involved volumes regardless\nof the specific curing mechanisms, which could play a crucial role in\noptimizing photocuring-based additive manufacturing."
    },
    {
        "anchor": "Frictional Impacts in Multibody Systems: A unifying slipping and sticking frictional impact model for multibody\nsystems in contact with a frictional surface is presented. It is shown that the\nmodel can lead to energetic consistency in both slip state and stick state upon\nimposing specific constraints on the coefficient of friction (CoF) and the\ncoefficient of restitution (CoR). A discriminator in the form of a quadratic\nfunction of the pre-impact velocity is introduced based on isotropic Coulomb\nconstraint such that its sign determines whether the impact occurs in the\nsticking mode or in the slipping mode just prior to the contact. Solving the\nzero-crossings of such a function in terms of the CoF and the CoR variables\nleads to another discriminator called Critical CoF, which is the lowest static\nCoF required to prevent the subsequent impulse vector violating the isotropic\nfriction cone constraint. Investigating conditions for the energetically\nconsistent impact model reveals that the maximum values of either CoR or CoF\nshould be limited depending on stick state or slip state. Furthermore, it is\nshown that these upper-bound limits in conjunction with the introduced Critical\nCoF variable can be used to specify the admissible set of CoR and CoF\nparameters, which can be represented by two distinct regions in the plan of CoF\nversus CoR.",
        "positive": "Formation and structure of the microemulsion phase in two-dimensional\n  ternary AB+A+B polymeric emulsions: We present an analysis of the structure of the fluctuation-induced\nmicroemulsion phase in a ternary blend of balanced AB diblock copolymers with\nequal amounts of A and B homopolymers. To this end, graphical analysis methods\nare employed to characterize two-dimensional configuration snapshots obtained\nwith the recently introduced Field-Theoretic Monte Carlo (FTMC) method. We find\nthat a microemulsion forms when the mean curvature diameter of the lamellar\nphase coincides roughly with the periodicity of the lamellar phase. Further, we\nprovide evidence to the effect of a subclassification of the microemulsion into\na genuine and a defect-driven region."
    },
    {
        "anchor": "A Random Loop Model for Long Polymers: While the structure of chromatin has been studied in great detail on length\nscales below 30 nm, amazingly little is known about the higher-order folding\nmotifs of chromatin in interphase. Recent experiments give evidence that the\nfolding may depend locally on gene density and transcriptional activity and\nshow a leveling-off at long distances where approximately $<R^2> \\sim O(1)$. We\npropose a new model that can explain this leveling-off by the formation of\nrandom loops. We derive an analytical expression for the mean square\ndisplacement between two beads where the average is taken over the thermal\nensemble with a fixed but random loop configuration, while quenched averaging\nover the ensemble of different loop configurations -- which turns out to be\nequivalent to averaging over an ensemble of random matrices -- is performed\nnumerically. A detailed investigation of this model shows that loops on all\nscales are necessary to fit experimental data.",
        "positive": "A Renormalization Group Procedure for Fiber Bundle Models: We introduce two versions of a renormalization group scheme for the equal\nload sharing fiber bundle model. The renormalization group is based on\nformulating the fiber bundle model in the language of damage mechanics. A\ncentral concept is the work performed on the fiber bundle to produce a given\ndamage. The renormalization group conserves this work. In the first version of\nthe renormalization group, we take advantage of ordering the strength of the\nindividual fibers. This procedure, which is the simpler one, gives EXACT\nresults -but cannot be generalized to other fiber bundle models such as the\nlocal load sharing one. The second renormalization group scheme based on the\nphysical location of the individual fibers may be generalized to other fiber\nbundle models."
    },
    {
        "anchor": "Rethinking Ductility -- A Study Into the Size-Affected Fracture of\n  Polymers: Ductility quantifies a material's capacity for plastic deformation, and it is\na key property for preventing fracture driven failure in engineering parts.\nWhile some brittle materials exhibit improved ductility at small scales, the\nprocesses underlying this phenomenon are not well understood. This work\nestablishes a mechanism for the origin of ductility via an investigation of\nsize-affected fracture processes and polymer degree of conversion (DC) in\ntwo-photon lithography (TPL) fabricated materials. Microscale single edge notch\nbend ($\\mu$SENB) specimens were written with widths from 8 to 26 $\\mu$m and\nwith different laser powers and post-write thermal annealing to control the DC\nbetween 17\\% and 80\\%. We find that shifting from low to high DC predictably\ncauses a $\\sim$3x and $\\sim$4x increase in strength and bending stiffness,\nrespectively, but that there is a corresponding $\\sim$6x decrease in fracture\nenergy from 180 $J/m^2$ to 30 $J/m^2$. Notably, this reduced fracture energy is\naccompanied by a ductile-to-brittle transition (DBT) in the failure behavior.\nUsing finite element analysis, we demonstrate that the DBT occurs when the\nfracture yielding zone size ($r_p$) approaches the sample width, corresponding\nwith a known fracture size-affected transition from flaw-based to\nstrength-based failure. This finding provides a crucial insight that ductility\nis a size-induced property that occurs when features are reduced below a\ncharacteristic fracture length scale and that strength, stiffness, and\ntoughness alone are insufficient predictors of ductility.",
        "positive": "Sedimentation of a two-dimensional colloidal mixture exhibiting\n  liquid-liquid and gas-liquid phase separation: a dynamical density functional\n  theory study: We present dynamical density functional theory results for the time evolution\nof the density distribution of a sedimenting model two-dimensional binary\nmixture of colloids. The interplay between the bulk phase behaviour of the\nmixture, its interfacial properties at the confining walls, and the\ngravitational field gives rise to a rich variety of equilibrium and\nnon-equilibrium morphologies. In the fluid state, the system exhibits both\nliquid-liquid and gas-liquid phase separation. As the system sediments, the\nphase separation significantly affects the dynamics and we explore situations\nwhere the final state is a coexistence of up to three different phases. Solving\nthe dynamical equations in two-dimensions, we find that in certain situations\nthe final density profiles of the two species have a symmetry that is different\nfrom that of the external potentials, which is perhaps surprising, given the\nstatistical mechanics origin of the theory. The paper concludes with a\ndiscussion on this."
    },
    {
        "anchor": "Softening of the Hertz indentation contact in nematic elastomers: Polydomain liquid crystalline (nematic) elastomers have highly unusual\nmechanical properties, dominated by the dramatically non-linear stress-strain\nresponse that reflects stress-induced evolution of domain patterns. Here, we\nstudy the classical Hertz indentation problem in such a material.\nExperimentally, we find that polydomain nematic elastomers display a smaller\nexponent than the classical 3/2 in the load vs. indentation depth response.\nThis is puzzling: asymptotically a softer stress-strain response requires a\nlarger exponent at small loads. We resolve this by theory where three regimes\nare identified -- an initial elastic regime for shallow indentation that is\nobscured in experiment, an intermediate regime where local domain pattern\nevolution leads to a smaller scaling in agreement with experiments, and a final\nstiffening regime where the completion of local domain evolution returns the\nresponse to elastic. This three-regime structure is universal, but the\nintermediate exponent is not. We discuss how our work reveals a new mechanism\nof enhanced adhesion for pressure-sensitive adhesion of nematic elastomers.",
        "positive": "Insights on the local dynamics induced by thermal cycling in granular\n  matter: In this letter, we report results on the effect of temperature variations on\na granular assembly through Molecular Dynamic simulations of a 2D granular\ncolumn. Periodic dilation of the grains are shown to perfectly mimic such\nthermal cycling, and allows to rationalize the link between the compaction\nprocess, the local grains dynamics and finite size effects. Here we show that\nthe individual grain properties, namely their roughness and elastic modulus\ndefine a minimal cycling amplitude of temperature \\Delta Tc below which the\ndynamics is intermittent and spatially heterogeneous while confined into\nlocalized regions recently coined \"hot spot\" [Amon et al., Phys. Rev. Lett.\n108, 135502 (2012)]. Above \\Delta Tc, the whole column flows while the grains\ndynamics ranges continuously from cage-like at the bottom of the column to\npurely diffusive at the top. Our results provide a solid framework for the\nfutur use of thermal cycling as an alternate driving method for soft glassy\nmaterials."
    },
    {
        "anchor": "Interevent time distributions of avalanche dynamics: Physical systems characterized by stick-slip dynamics often display\navalanches. Regardless of the diversity of their microscopic structure, these\nsystems are governed by a power-law distribution of avalanche size and\nduration. Here we focus on the interevent times between avalanches and show\nthat, unlike their distributions of size and duration, the interevent time\ndistributions are able to distinguish different mechanical states of the\nsystem, characterized by different volume fractions or confining pressures. We\nuse experiments on granular systems and numerical simulations of emulsions to\nshow that systems having the same probability distribution for avalanche size\nand duration can have different interevent time distributions. Remarkably, for\nlarge packing ratios, these interevent time distributions look similar to those\nfor earthquakes and are indirect evidence of large space-time correlations in\nthe system. Our results therefore indicate that interevent time statistics are\nmore informative to characterize the dynamics of avalanches.",
        "positive": "Helical locomotion in granular media: The physical mechanisms that bring about the propulsion of a rotating helix\nin a granular medium are considered. A propulsive motion along the axis of the\nrotating helix is induced by both symmetry breaking due to the helical shape,\nand the anisotropic frictional forces undergone by all segments of the helix in\nthe medium. Helix dynamics is studied as a function of helix rotation speed and\nits geometrical parameters. The effect of the granular pressure and the applied\nexternal load were also investigated. A theoretical model is developed based on\nthe anisotropic frictional force experienced by a slender body moving in a\ngranular material, to account for the translation speed of the helix. A good\nagreement with experimental data is obtained, which allows for predicting the\nhelix design to propel optimally within granular media. These results pave the\nway for the development of an efficient sand-robot operating according to this\nmode of locomotion."
    },
    {
        "anchor": "Effect of pH on the complex coacervation and on the formation of layers\n  of sodium alginate and PDADMAC: In this study, we investigated the thermodynamic features of a system based\non oppositely charged polyelectrolytes, sodium alginate, and\npoly(diallyldimethylammonium chloride) (PDADMAC) at different pH values.\nAdditionally, a comparison of the effects of the thermodynamic parameters on\nthe growth of the layers based on the same polymers is presented. For this\ninvestigation, different techniques were combined to compare results from the\nassociation in solution and co-assembled layers at the silicon surface. Dynamic\nlight scattering (DLS) and isothermal titration calorimetry (ITC) were used for\nstudies in solution, and the layer-by-layer technique was employed for the\npreparation of the polymer layers. Ellipsometry and atomic force microscopy\n(AFM) were used to characterize the layer thickness growth as a function of the\nsolution pH, and interferometric confocal microscopy was employed to analyze\nthe topography and roughness of the films. The layers grown for the\nPDADMAC/sodium alginate system demonstrated pH sensitivity with either linear\nor exponential behavior, depending on the pH values of the polyelectrolyte\nsolutions. The layer thicknesses measured using ellipsometry and AFM data were\nin good agreement. Additionally, a pH influence on the roughness and topography\nof the films was observed. Films from basic dipping solutions resulted in\nsurfaces that were more homogeneous with less roughness; in contrast, films\nwith more layers and those formed in a low-pH dipping solution were rougher and\nless homogeneous.",
        "positive": "Mechanochemical action of the dynamin protein: Dynamin is a ubiquitous GTPase that tubulates lipid bilayers and is\nimplicated in many membrane severing processes in eukaryotic cells. Setting the\ngrounds for a better understanding of this biological function, we develop a\ngeneralized hydrodynamics description of the conformational change of large\ndynamin-membrane tubes taking into account GTP consumption as a free energy\nsource. On observable time scales, dissipation is dominated by an effective\ndynamin/membrane friction and the deformation field of the tube has a simple\ndiffusive behavior, which could be tested experimentally. A more involved,\nsemi-microscopic model yields complete predictions for the dynamics of the tube\nand possibly accounts for contradictory experimental results concerning its\nchange of conformation as well as for plectonemic supercoiling."
    },
    {
        "anchor": "Depinning of semiflexible polymers in (1+1) dimensions: We present a theoretical analysis of a simple model of the depinning of an\nanchored semiflexible polymer from a fixed planar substrate in (1+1)\ndimensions. We consider a polymer with a discrete sequence of pinning sites\nalong its contour. Using the scaling properties of the conformational\ndistribution function in the stiff limit and applying the necklace model of\nphase transitions in quasi-one-dimensional systems, we obtain a melting\ncriterion in terms of the persistence length, the spacing between pinning\nsites, a microscopic effective length which characterizes a bond, and the bond\nenergy. The limitations of this and other similar approaches are also\ndiscussed. In the case of force-induced unbinding, it is shown that the bending\nrigidity favors the unbinding through a ``lever-arm effect''.",
        "positive": "How superlocalization affects Vibrational Energy Exchange process in\n  proteins: Recent experimental findings on a protein showed the diffusion of vibrational\nenergy does not occur along the backbone interaction,as it might be expected,\nbut prevalently on non-bonded contacts. These results are explained presenting\na theoretical picture, supported by computational calculations, that accounts\nfor these different behaviors in vibrational energy exchange process showing\nthe collective motions on the backbone present a $superlocalized$ nature as\ntheir decay with the distance $r$ is $exp(-r^{d})$ with $d \\sim 1.8$, whereas\nthose associated to non-bonded contacts result simply localized with $d \\sim\n1$."
    },
    {
        "anchor": "The swelling and shrinking of spherical thermo-responsive hydrogels: Thermo-responsive hydrogels are a promising material for creating\ncontrollable actuators for use in micro-scale devices, since they expand and\ncontract significantly (absorbing or expelling fluid) in response to relatively\nsmall temperature changes. Understanding such systems can be difficult because\nof the spatially- and temporally-varying properties of the gel, and the complex\nrelationships between the fluid dynamics, elastic deformation of the gel and\nchemical interaction between the polymer and fluid. We address this using a\nporo-elastic model, considering the dynamics of a thermo-responsive spherical\nhydrogel after a sudden change in the temperature that should result in\nsubstantial swelling or shrinking. We focus on two model examples, with\nequilibrium parameters extracted from data in the literature. We find a range\nof qualitatively different behaviours when swelling and shrinking, including\ncases where swelling and shrinking happen smoothly from the edge, and other\nsituations which result in the formation of an inwards-travelling spherical\nfront that separates a core and shell with markedly different degrees of\nswelling. We then characterise when each of these scenarios is expected to\noccur. An approximate analytical form for the front dynamics is developed, with\ntwo levels of constant porosity, that well-approximates the numerical\nsolutions. This system can be evolved forward in time, and is simpler to solve\nthan the full numerics, allowing for more efficient predictions to be made,\nsuch as when deciding dosing strategies for drug-laden hydrogels.",
        "positive": "Correlations and Freezing in Steadily Settling Suspensions: We study the liquid-solid transition in a collection of interacting particles\nmoving through a dissipative medium under the action of a constant, spatially\nuniform external force, e.g. a charge-stabilized suspension in a fluidized bed\nor a flux-point lattice moving through a thin, current-carrying slab of type II\nsuperconductor. The mobility of a given region in these systems is in general a\nfunction of the local concentration. We show that the structure factor peak is\nsuppressed in an anisotropic manner as a result of this effect, resulting in a\nshift of the crystal-liquid phase boundary towards the crystal side. A\nnonequilibrium phase diagram is presented."
    },
    {
        "anchor": "Maximum Valency Lattice Gas Models: We study lattice gas models with the imposition of a constraint on the\nmaximum number of bonds (nearest neighbor interactions) that particles can\nparticipate in. The critical parameters, as well as the coexistence region are\nstudied using the mean field approximation and the Bethe-Peierls approximation.\nWe find that the reduction of the number of interactions suppresses the\ntemperature-density region where the liquid and gas phases coexist. We confirm\nthese results from simulations using the histogram reweighting method employing\ngrand Canonical Monte Carlo simulations.",
        "positive": "Elastocapillary coiling of an elastic rod inside a drop: Capillary forces acting at the surface of a liquid drop can be strong enough\nto deform small objects and recent studies have provided several examples of\nelastic instabilities induced by surface tension. We present such an example\nwhere a liquid drop sits on a straight fiber, and we show that the liquid\nattracts the fiber which thereby coils inside the drop. We derive the\nequilibrium equations for the system, compute bifurcation curves, and show the\npacked fiber may adopt several possible configurations inside the drop. We use\nthe energy of the system to discriminate between the different configurations\nand find a intermittent regime between two-dimensional and three-dimensional\nsolutions as more and more fiber is driven inside the drop."
    },
    {
        "anchor": "Comb-like polymers inside nanoscale pores: A new method of polymer characterization, based on permeation studies using\nnanoscale pores, was recently proposed by Brochard and de Gennes. In the\npresent paper, we study how this method, initially developped for star polymers\ncan be extended to comb-like polymers.",
        "positive": "Edwards entropy and compactivity in a model of granular matter: Formulating a statistical mechanics for granular matter remains a significant\nchallenge, in part, due to the difficulty associated with a complete\ncharacterization of the systems under study. We present a fully characterized\nmodel of a granular material consisting of $N$ two-dimensional, frictionless,\nhard discs, confined between hard walls, including a complete enumeration of\nall possible jammed structures. We show the properties of the jammed packings\nare independent of the distribution of defects within the system and that all\nthe packings are isostatic. This suggests the assumption of equal probability\nfor states of equal volume, which provides one possible way of constructing the\nequivalent of a microcanonical ensemble, is likely to be vaild for our model.\nAn application of the second law of thermodynamics involving two subsystems in\ncontact shows that the expected spontaneous equilibration of defects between\nthe two is accompanied by an increase in entropy and that the equilibirum,\nobtained by entropy maximization, is characterized by the equality of\ncompactivities. Finally, we explore the properties of the equivalent to the\ncanonical ensemble for this system."
    },
    {
        "anchor": "Structure of vortices in two-component Bose-Einstein condensates: We develop a three-dimensional analysis of the phase separation of\ntwo-species Bose-Einstein condensates in the presence of vorticity within the\nThomas-Fermi approximation. We find different segregation features according to\nwhether the more repulsive component is in a vortex or in a vortex-free state.\nAn application of this study is aimed at describing systems formed by two\nalmost immiscible species of rubidium-87 that are commonly used in\nBose-Einstein condensation experiments. In particular, in this work we\ncalculate the density profiles of condensates for the same conditions as the\nstates prepared in the experiments performed at JILA [Matthews et al., Phys.\nRev. Lett. 83, 2498 (1999)]",
        "positive": "Transition from turbulent to coherent flows in confined\n  three-dimensional active fluids: Transport of fluid through a pipe is essential for the operation of\nmacroscale machines and microfluidic devices. Conventional fluids only flow in\nresponse to external pressure. We demonstrate that an active isotropic fluid,\ncomprised of microtubules and molecular motors, autonomously flows through\nmeter-long three-dimensional channels. We establish control over the magnitude,\nvelocity profile and direction of the self-organized flows, and correlate these\nto the structure of the extensile microtubule bundles. The inherently\nthree-dimensional transition from bulk-turbulent to confined-coherent flows\noccurs concomitantly with a transition in the bundle orientational order near\nthe surface, and is controlled by a scale-invariant criterion related to the\nchannel profile. The non-equilibrium transition of confined isotropic active\nfluids can be used to engineer self-organized soft machines."
    },
    {
        "anchor": "Unexpected swelling of stiff DNA in a polydisperse crowded environment: We investigate the conformations of DNA-like stiff chains, characterized by\ncontour length ($L$) and persistence length ($l_p$), in a variety of crowded\nenvironments containing mono disperse soft spherical (SS) and spherocylindrical\n(SC) particles, mixture of SS and SC, and a milieu mimicking the composition of\nproteins in $E. coli.$ cytoplasm. The stiff chain, whose size modestly\nincreases in SS crowders up to $\\phi\\approx 0.1$, is considerably more compact\nat low volume fractions ($\\phi \\leq 0.2$) in monodisperse SC particles than in\na medium containing SS particles. A 1:1 mixture of SS and SC crowders induces\ngreater chain compaction than the pure SS or SC crowders at the same $\\phi$\nwith the effect being highly non-additive. We also discover a counter-intuitive\nresult that polydisperse crowding environment, mimicking the composition of a\ncell lysate, swells the DNA-like polymer, which is in stark contrast to the\nsize reduction of flexible polymer in the same milieu. Trapping of the stiff\nchain in a fluctuating tube-like environment created by large-sized crowders\nexplains the dramatic increase in size and persistence length of the stiff\nchain. In the polydisperse medium, mimicking the cellular environment, the size\nof the DNA (or related RNA) is determined by $L/l_p$. At low $L/l_p$ the size\nof the polymer is unaffected whereas there is a dramatic swelling at\nintermediate value of $L/l_p$. We use these results to provide insights into\nrecent experiments on crowding effects on RNA, and also make testable\npredictions.",
        "positive": "Rapid local compression in active gels is caused by nonlinear network\n  response: The actin cytoskeleton in living cells generates forces in conjunction with\nmyosin motor proteins to directly and indirectly drive essential cellular\nprocesses. The semiflexible filaments of the cytoskeleton can respond\nnonlinearly to the collective action of motors. We here investigate mechanics\nand force generation in a model actin cytoskeleton, reconstituted in vitro, by\nobserving the response and fluctuations of embedded micron-scale probe\nparticles. Myosin mini-filaments can be modelled as force dipoles and give rise\nto deformations in the surrounding network of cross-linked actin. Anomalously\ncorrelated probe fluctuations indicate the presence of rapid local compression\nof the network that emerges in addition to the ordinary linear shear elastic\n(incompressible) response to force dipoles. The anomalous propagation of\ncompression can be attributed to the nonlinear response of actin filaments to\nthe microscopic forces, and is quantitatively consistent with motor-generated\nlarge-scale stiffening of the gels."
    },
    {
        "anchor": "3D Brownian Diffusion of Submicron-Sized Particle Clusters: We report on the translation and rotation of particle clusters made through\nthe combination of spherical building blocks. These clusters present ideal\nmodel systems to study the motion of objects with complex shape. Because they\ncould be separated into fractions of well-defined configurations on a\nsufficient scale and their overall dimensions were below 300 nm, the\ntranslational and rotational diffusion coefficients of particle duplets,\ntriplets and tetrahedrons could be determined by a combination of polarized\ndynamic light scattering (DLS) and depolarized dynamic light scattering (DDLS).\nThe use of colloidal clusters for DDLS experiments overcomes the limitation of\nearlier experiments on the diffusion of complex objects near surfaces because\nthe true 3D diffusion can be studied. When the exact geometry of the complex\nassemblies is known, different hydrodynamic models for calculating the\ndiffusion coefficient for objects with complex shapes could be applied. Because\nhydrodynamic friction must be restricted to the cluster surface the so-called\nshell model, in which the surface is represented as a shell of small friction\nelements, was most suitable to describe the dynamics. A quantitative comparison\nof the predictions from theoretical modeling with the results obtained by DDLS\nshowed an excellent agreement between experiment and theory.",
        "positive": "Runaway electrification of friable self-replicating granular matter: We establish that the nonlinear dynamics of collisions between particles\nfavors the charging of a insulating, friable, self-replicating granular\nmaterial that undergoes nucleation, growth, and fission processes; we\ndemonstrate with a minimal dynamical model that secondary nucleation produces a\npositive feedback in an electrification mechanism that leads to runaway\ncharging. We discuss ice as an example of such a self-replicating granular\nmaterial: We confirm with laboratory experiments in which we grow ice from the\nvapor phase in situ within an environmental scanning electron microscope that\ncharging causes fast-growing and easily breakable palm-like structures to form,\nwhich when broken off may form secondary nuclei. We propose that thunderstorms,\nboth terrestrial and on other planets, and lightning in the solar nebula are\ninstances of such runaway charging arising from this nonlinear dynamics in\nself-replicating granular matter."
    },
    {
        "anchor": "Studies on binary mixtures of nematic liquid crystals made of strongly\n  polar molecules with identical cores and antagonistic orientation of\n  permanent dipoles: We report experimental studies on optical (birefringence, $\\Delta n$),\ndielectric $(\\Delta \\varepsilon)$ and bend-splay elastic anisotropies ($\\Delta\nK=K_{33}-K_{11})$ of a few mixtures of two nematic liquid crystals, namely\nCCH-7 and CCN-47, made of highly polar molecules with identical cores and\nantagonistic orientation of permanent dipoles. In particular, the polar group\n(-CN) attached to the bicyclohexane core of CCH-7 is oriented along the\nlongitudinal direction whereas, in CCN-47, it is oriented along the transverse\ndirection. We show that apart from the significant contribution to the optical\nand dielectric anisotropies, the antagonistic orientation of strongly polar\ngroups plays a crucial role in determining the bend-splay elastic anisotropy.\nThe elastic properties are explained based on a model proposed by Priest,\nconsidering the effect of intermolecular association and the resulting\nlength-to-width ratio of the molecules.",
        "positive": "Bouncing behavior and dissipative characterization of a chain-filled\n  granular damper: We have experimentally investigated the bouncing behavior and damping\nperformance of a container partially filled with granular chains, namely a\nchain-filled damper. The motion of the chain-filled damper, recorded by a\nparticle tracing technology, demonstrates that the granular chains can\nefficiently absorb the collisional energy of the damper. We extract both the\nrestitution coefficient of the first collision and the total flight time to\ncharacterize the dissipation ability of the damper. Two containers and three\ntypes of granular chains, different in size, stiffness and restitution\ncoefficient, are used to examine the experimental results. We find that the\nrestitution coefficient of the first collision of a single-chain-filled damper\ncan linearly tend to vanish with increasing the chain length and obtain a\nminimum filling mass required to cease the container at the first collision (no\nrebound). When the strong impact occurs, the collisional absorption efficiency\nof a chain-filled damper is superior to a monodisperse-particle-filled damper.\nFurthermore, the longer the chains are, the better the dissipative effect is."
    },
    {
        "anchor": "Exploiting anisotropic particle shape to electrostatically assemble\n  colloidal molecules with high yield and purity: Hypothesis: Colloidal molecules with anisotropic shapes and interactions are\npowerful model systems for deciphering the behavior of real molecules and\nbuilding units for creating materials with designed properties. While many\nstrategies for their assembly have been developed, they typically yield a broad\ndistribution or are limited to a specific type. We hypothesize that the shape\nand relative sizes of colloidal particles can be exploited to efficiently\ndirect their assembly into colloidal molecules of desired valence.\n  Experiments: We exploit electrostatic self-assembly of negatively charged\nspheres made from either polystyrene or silica onto positively charged hematite\ncubes. We thoroughly analyze the role of the shape and size ratio of particles\non the cluster size and yield of colloidal molecules.\n  Findings: Using a combination of experiments and simulations, we demonstrate\nthat cubic particle shape is crucial to generate high yields of distinct\ncolloidal molecules over a wide variety of size ratios. We find that\nelectrostatic repulsion between the satellite spheres is important to leverage\nthe templating effect of the cubes, leading the spheres to preferentially\nassemble on the facets rather than the edges and corners of the cube.\nFurthermore, we reveal that our protocol is not affected by the specific choice\nof the material of the colloidal particles. Finally, we show that the permanent\nmagnetic dipole moment of the hematite cubes can be utilized to separate\ncolloidal molecules from non-assembled satellite particles. Our simple and\neffective strategy might be extended to other templating particle shapes,\nthereby greatly expanding the library of colloidal molecules that can be\nachieved with high yield and purity.",
        "positive": "Nonlinear rheological properties of dense colloidal dispersions close to\n  a glass transition under steady shear: The nonlinear rheological properties of dense colloidal suspensions under\nsteady shear are discussed within a first principles approach. It starts from\nthe Smoluchowski equation of interacting Brownian particles in a given shear\nflow, derives generalized Green-Kubo relations, which contain the transients\ndynamics formally exactly, and closes the equations using mode coupling\napproximations. Shear thinning of colloidal fluids and dynamical yielding of\ncolloidal glasses arise from a competition between a slowing down of structural\nrelaxation, because of particle interactions, and enhanced decorrelation of\nfluctuations, caused by the shear advection of density fluctuations. The\nintegration through transients approach takes account of the dynamic\ncompetition, translational invariance enters the concept of wavevector\nadvection, and the mode coupling approximation enables to quantitatively\nexplore the shear-induced suppression of particle caging and the resulting\nspeed-up of the structural relaxation. Extended comparisons with shear stress\ndata in the linear response and in the nonlinear regime measured in model\nthermo-sensitive core-shell latices are discussed. Additionally, the single\nparticle motion under shear observed by confocal microscopy and in computer\nsimulations is reviewed and analysed theoretically."
    },
    {
        "anchor": "Characteristics of Respiratory Microdroplet Nuclei on Common Substrates: To evaluate the role of common substrates in the transmission of respiratory\nviruses, uniformly distributed microdroplets of artificial saliva were\ngenerated using an advanced inkjet printing technology to replicate the aerosol\ndroplets, and subsequently deposited on five substrates, including glass, PTFE,\nstainless steel, ABS, and melamine. The droplets were found to evaporate within\na short timeframe, which is consistent with previous reports concerning the\ndrying kinetics of picolitre droplets. Using fluorescence microscopy and atomic\nforce microscopy, we found that the surface deposited microdroplet nuclei\npresent two distinctive morphological features as the result of their drying\nmode, which is controlled by both interfacial energy and surface roughness.\nNanomechanical measurements confirm that the nuclei deposited on all substrates\npossess similar surface adhesion and Youngs modulus, supporting the proposed\ncoreshell structure of the nuclei. We suggest that appropriate antiviral\nsurface strategies, e.g. functionalisation, chemical deposition, could be\ndeveloped to modulate the evaporation process of microdroplet nuclei, and\nsubsequently mitigate the possible surface viability and transmissibility of\nrespiratory virus.",
        "positive": "Visualization by optical fluorescence of two-phase flow in a\n  three-dimensional porous medium: Slow flow of a single fluid through a porous medium is well understood on a\nmacroscopic level through Darcy's law, a linear relation between flow rate and\na combination of pressure differences, viscosity, and gravitational forces.\nTwo-phase flow is complicated by the interface separating the fluids, but\nunderstanding of two-dimensional, two-phase flow has been obtained from\nexperiments using transparent cells. In most three-dimensional media, however,\nvisual observation is difficult. Here, we present preliminary results of\nexperiments on a model medium consisting of randomly packed glass spheres, in\nwhich one fluorescent liquid invades another. By refractive index matching and\nscanning with a sheet-shaped laser beam, we obtain slices of the flow patterns,\nwhich we combine into three-dimensional pictures. We observe a compact region\nof invading fluid, surrounded by finger-like protrusions. The compact region\nbecomes more dominant with increasing invader flow rate. The patterns are\ntheoretically analyzed in terms of the interplay between gravitational,\nviscous, and capillary forces."
    },
    {
        "anchor": "Hydrodynamic Effects in Kinetics of Phase Separation in Binary Fluids:\n  Critical versus off-critical compositions: Via hydrodynamics preserving molecular dynamics simulations we study growth\nphenomena in a phase separating symmetric binary mixture model. We quench\nhigh-temperature homogeneous configurations to state points inside the\nmiscibility gap, for various mixture compositions. For compositions around the\nsymmetric or critical value we capture the rapid linear viscous hydrodynamic\ngrowth due to advective transport of material through tube-like interconnected\ndomains. The focus of the work, however, is on compositions close to any of the\nbranches of the coexistence curve. In this case, the growth in the system,\nfollowing nucleation of droplets of the minority species, occurs via\ncoalescence mechanism. Using state-of-the-art techniques we have identified\nthat these droplets, between collisions, exhibit diffusive motion. The value of\nthe exponent for the power-law growth, related to this diffusive coalescence\nmechanism, as the composition keeps departing from the critical value, has been\nestimated. This nicely agrees with a theoretical number. These results are\ncompared with the growth that occurs via particle diffusion mechanism, in\nnon-hydrodynamic environment.",
        "positive": "Bilayer sheet protrusions and budding from bilayer membranes induced by\n  hydrolysis and condensation reactions: Shape transformations of flat bilayer membranes and vesicles induced by\nhydrolysis and condensation reactions of amphiphilic molecules are studied\nusing coarse-grained molecular dynamics simulations. The hydrolysis and\ncondensation reactions result in the formation and dissociation of amphiphilic\nmolecules, respectively. Asymmetric reactions between the inner and outer\nleaflets of a vesicle can transport amphiphilic molecules between the leaflets.\nIt is found that the resulting area difference between the two leaflets induces\nbilayer sheet protrusion~(BP) and budding at low reduced volumes of the\nvesicles, whereas BP only occurs at high reduced volumes. The probabilities of\nthese two types of transformations depend on the shear viscosity of the\nsurrounding fluids compared to the membrane as well as the reaction rates. A\nhigher surrounding fluid viscosity leads to more BP formation. The\ninhomogeneous spatial distribution of the hydrophobic reaction products forms\nthe nuclei of BP formation, and faster diffusion of the products enhances BP\nformation. Our results suggest that adjustment of the viscosity is important to\ncontrol membrane shape transformations in experiments."
    },
    {
        "anchor": "Elastic Properties, Yield Surface and Flow Rule of Nanopowder Compacts: Different compaction processes of the nanosized granular system, which is a\nprototype of an alumina nanopowder, are studied by the granular dynamics\nmethod. For all processes: compaction curves ''density vs. pressure'' of the\npowder compact are calculated, the elastic and the plastic parts are extracted\nfrom the total deformation, the body elastic moduli are determined within the\nisotropic solid approximation. The inadequacy of the isotropy approximation is\nestablished. The nanopowder yield surface is constructed in the space of stress\ntensor invariants. The inapplicability of the traditional associated flow rule\nfor description of oxide nanopowders compaction processes is revealed. An\nalternative flow rule is suggested.",
        "positive": "Optimal motion of triangular magnetocapillary swimmers: A system of ferromagnetic particles trapped at a liquid-liquid interface and\nsubjected to a set of magnetic fields (magnetocapillary swimmers) is studied\nnumerically using a hybrid method combining the pseudopotential lattice\nBoltzmann method and the discrete element method. After investigating the\nequilibrium properties of a single, two and three particles at the interface,\nwe demonstrate a controlled motion of the swimmer formed by three particles. It\nshows a sharp dependence of the average center-of-mass speed on the frequency\nof the time-dependent external magnetic field. Inspired by experiments on\nmagnetocapillary microswimmers, we interpret the obtained maxima of the swimmer\nspeed by the optimal frequency centered around the characteristic relaxation\ntime of a spherical particle. It is also shown that the frequency corresponding\nto the maximum speed grows and the maximum average speed decreases with\nincreasing inter-particle distances at moderate swimmer sizes. The findings of\nour lattice Boltzmann simulations are supported by bead-spring model\ncalculations."
    },
    {
        "anchor": "Generalizing Rosenfeld's excess-entropy scaling to predict long-time\n  diffusivity in dense fluids of Brownian particles: From hard to ultrasoft\n  interactions: Computer simulations are used to test whether a recently introduced\ngeneralization of Rosenfeld's excess-entropy scaling method for estimating\ntransport coefficients in systems obeying molecular dynamics can be extended to\npredict long-time diffusivities in fluids of particles undergoing Brownian\ndynamics in the absence of interparticle hydrodynamic forces. Model fluids with\ninverse-power-law, Gaussian-core, and Hertzian pair interactions are\nconsidered. Within the generalized Rosenfeld scaling method, long-time\ndiffusivities of ultrasoft Gaussian-core and Hertzian particle fluids, which\ndisplay anomalous trends with increasing density, are predicted (to within 20%)\nbased on knowledge of interparticle interactions, excess entropy, and scaling\nbehavior of simpler inverse-power-law fluids.",
        "positive": "Liquid metals: early contributions and some recent developments: We illustrate in this contribution the progress in the theoretical study of\nliquid metals made in the last decades, starting from the example of liquid\ngallium and the early work in Jean-Pierre Badiali's group. This was based on\nthe combination of the perturbation theory with pseudo-potentials for the\nelectrons and the liquid state theory for the ions. More recent developments\ncombining ab initio and classical molecular dynamics simulations are finally\nillustrated on the example of glass forming alloys."
    },
    {
        "anchor": "Switch of lamellae orientation in slits: Effect of hydrophilicity of the confining walls on lamellar phases in\noil-water-surfactant mixtures is studied in a slit geometry. In contrast to\nstrongly hydrophilic or hydrophobic walls, which induce parallel orientation of\nlamellae, the lamellae can be oriented perpendicularly to the neutral walls\nwhen the material properties and the termodynamical state of the sample are\nsuitably chosen. When the elastic energy associated with compression or\ndecompression of the lamellae parallel to very weakly hydrophilic walls is\nsufficiently large, then changes of the film thickness lead to a switch from\nthe parallel to the perpendicular orientation of the lamellae. Our general\narguments are confirmed by explicit mean-field calculations in a lattice vector\nmodel.",
        "positive": "Microstructure, morphology and lifetime of armored bubbles exposed to\n  surfactants: We report the behavior of particle-stabilized bubbles (armored bubbles) when\nexposed to various classes and concentrations of surfactants. The bubbles are\nnon-spherical due to the jamming of the particles on the interface and are\nstable to dissolution prior to the addition of surfactant. We find that the\ndissolving bubbles exhibit distinct morphological, microstructural, and\nlifetime changes, which correlate with the concentration of surfactant\nemployed. For low concentrations of surfactant an armored bubble remains\nnon-spherical while dissolving, while for concentrations close to and above the\nsurfactant CMC a bubble reverts to a spherical shape before dissolving. We\npropose a microstructural interpretation, supported by our experimental\nobservations of particle dynamics on the bubble interface, that recognizes the\nrole of interfacial jamming and stresses in particle stabilization and\nsurfactant-mediated destabilization of armored bubbles."
    },
    {
        "anchor": "The Jamming Transition in Granular Systems: Recent simulations have predicted that near jamming for collections of\nspherical particles, there will be a discontinuous increase in the mean contact\nnumber, Z, at a critical volume fraction, phi_c. Above phi_c, Z and the\npressure, P are predicted to increase as power laws in phi-phi_c. In\nexperiments using photoelastic disks we corroborate a rapid increase in Z at\nphi_c and power-law behavior above phi_c for Z and P. Specifically we find\npower-law increase as a function of phi-phi_c for Z-Z_c with an exponent beta\naround 0.5, and for P with an exponent psi around 1.1. These exponents are in\ngood agreement with simulations. We also find reasonable agreement with a\nrecent mean-field theory for frictionless particles.",
        "positive": "Electronic Excitation Response of DNA to High-energy Proton Radiation in\n  Water: The lack of molecular-level understanding for the electronic excitation\nresponse of DNA to charged particle radiation, such as high-energy protons,\nremains a fundamental scientific bottleneck in advancing proton and other ion\nbeam cancer therapies. In particular, the dependence of different types of DNA\ndamage on high-energy protons represents a significant knowledge void. Here we\nemploy first-principles real-time time-dependent density functional theory\nsimulation, using a massively-parallel supercomputer, to unravel the\nquantum-mechanical details of the energy transfer from high-energy protons to\nDNA in water. The calculations reveal that protons deposit significantly more\nenergy onto the DNA sugar-phosphate side chains than onto the nucleobases, and\ngreater energy transfer is expected onto the DNA side chains than onto water.\nAs a result of this electronic stopping process, highly energetic holes are\ngenerated on the DNA side chains as a source of oxidative damage."
    },
    {
        "anchor": "Reverse Janssen effect in narrow granular columns: When grains are added to a cylinder, the weight at the bottom is smaller than\nthe total weight of the column, which is partially supported by the lateral\nwalls through wall/grain frictional forces. This is known as the Janssen\neffect. Via a combined experimental and numerical investigation, here we\ndemonstrate a reverse Jansen effect whereby the fraction of the weight\nsupported by the base overcomes one. We characterize the dependence of this\nphenomenon on the various control parameters involved, rationalize the physical\nprocess responsible for the emergence of the compressional frictional forces\nresponsible for the anomaly, and introduce a model to reproduce our findings.\nContrary to prior assumptions, our results demonstrate that the constitutive\nrelation on a material element can depend on the applied stress.",
        "positive": "Interaction-motif-based classification of self-organizing metabolic\n  cycles: Particles that are catalytically-active and chemotactic can interact through\nthe concentration fields upon which they act, which in turn may lead to\nwide-scale spatial self-organization. When these active particles interact\nthrough several fields, these interactions gain an additional structure, which\ncan result in new forms of collective behaviour. Here, we study a mixture of\nactive species which catalyze the conversion of a substrate chemical into a\nproduct chemical, and chemotax in concentration gradients of both substrate and\nproduct. Such species develop non-reciprocal, specific interactions that we\ncoarse-grain into attractive and repulsive, which can lead to a potentially\ncomplex interaction network. We consider the particular case of a metabolic\ncycle of three species, each of which interacts with itself and both other\nspecies in the cycle. We find that the stability of a cycle of species that\nonly chemotax in gradients of their substrate is piloted by a set of two\nparameter-free conditions, which we use to classify the low number of\ncorresponding interaction networks. In the more general case of substrate- and\nproduct-chemotactic species, we can derive a set of two high-dimensional\nstability conditions, which can be used to classify the stability of all the\npossible interaction networks based on the self- and pair-interaction motifs\nthey contain. The classification scheme that we introduce can help guide future\nstudies on the dynamics of complex interaction networks and explorations of the\ncorresponding large parameter spaces in such metabolically active complex\nsystems."
    },
    {
        "anchor": "Fibonacci numbers in phyllotaxis : a simple model: A simple model is presented which explains the occurrence of high order\nFibonacci number parastichies in asteracae flowers by two distinct steps. First\nlow order parastichies result from the fact that a new floret, at its\nappearance is repelled by two former ones, then, in order to accommodate for\nthe increase of the radius, parastichies numbers have to evolve and can do it\nonly by applying the Fibonacci recurrence formula.",
        "positive": "Packing of soft asymmetric dumbbells: We use numerical simulations to study the phase behavior of a system of\npurely repulsive soft dumbbells as a function of size ratio of the two\ncomponents and their relative degree of deformability. We find a plethora of\ndifferent phases which includes most of the mesophases observed in\nself-assembly of block copolymers, but also crystalline structures formed by\nasymmetric, hard binary mixtures. Our results detail the phenomenological\nbehavior of these systems when softness is introduced in terms of two different\nclasses of inter-particle interactions: (a) the elastic Hertz potential, that\nhas a finite energy cost for complete overlap of any two components, and (b) a\ngeneric power-law repulsion with tunable exponent. We discuss how simple\ngeometric arguments can be used to account for the large structural variety\nobserved in these systems, and detail the similarities and differences in the\nphase behavior for the two classes of potentials under consideration."
    },
    {
        "anchor": "Normal-stress coefficients and rod climbing in colloidal dispersions: We calculate tractable microscopic expressions for the low-shear\nnormal-stress coefficients of colloidal dispersions. Although restricted to the\nlow rate regime, the presented formulas are valid for all volume fractions\nbelow the glass transition and for any interaction potential. Numerical results\nare presented for a system of colloids interacting via a hard-core attractive\nYukawa potential, for which we explore the interplay between attraction\nstrength and volume fraction. We show that the normal-stress coefficients\nexhibit nontrivial features close to the critical point and at high volume\nfractions in the vicinity of the reentrant glass transition. Finally, we\nexploit our formulas to make predictions about rod-climbing effects in\nattractive colloidal dispersions.",
        "positive": "Effective potentials in polyelectrolyte solutions: Using Poisson-Boltzmann equation and linear response theory, we derive an\neffective interaction potential due to a fixed charge distribution in a\nsolution containing polyelectrolytes and point salt. We obtain an expression\nfor the effective potential in terms of static structure factor using the\nintegral equation theories. To demonstrate the theory we apply it to Gaussian\nand rod-like polyelectrolytes and make connections to earlier theoretical works\nin some exact limits. We explore the role of both intra and inter polymer\ncorrelations, and the geometry of the polymers in the development of attractive\nregions in the effective potential as well as their effects on the screening\nlengths."
    },
    {
        "anchor": "Colloidal hard-rod fluids near geometrically structured substrates: Density functional theory is used to study colloidal hard-rod fluids near an\nindividual right-angled wedge or edge as well as near a hard wall which is\nperiodically patterned with rectangular barriers. The Zwanzig model, in which\nthe orientations of the rods are restricted to three orthogonal orientations\nbut their positions can vary continuously, is analyzed by numerical\nminimization of the grand potential. Density and orientational order profiles,\nexcess adsorptions, as well as surface and line tensions are determined. The\ncalculations exhibit an enrichment [depletion] of rods lying parallel and close\nto the corner of the wedge [edge]. For the fluid near the geometrically\npatterned wall, complete wetting of the wall -- isotropic liquid interface by a\nnematic film occurs as a two-stage process in which first the nematic phase\nfills the space between the barriers until an almost planar isotropic --\nnematic liquid interface has formed separating the higher-density nematic fluid\nin the space between the barriers from the lower-density isotropic bulk fluid.\nIn the second stage a nematic film of diverging film thickness develops upon\napproaching bulk isotropic -- nematic coexistence.",
        "positive": "Glassy Dynamics in Models of Confluent Tissue with Mitosis and Apoptosis: Recent work on particle-based models of tissues has suggested that any finite\nrate of cell division and cell death is sufficient to fluidize an epithelial\ntissue. At the same time, experimental evidence has indicated the existence of\nglassy dynamics in some epithelial layers despite continued cell cycling. To\naddress this discrepancy, we quantify the role of cell birth and death on\nglassy states in confluent tissues using simulations of an active vertex model\nthat includes cell motility, cell division, and cell death. Our simulation data\nis consistent with a simple ansatz in which the rate of cell-life cycling and\nthe rate of relaxation of the tissue in the absence of cell cycling contribute\nindependently and additively to the overall rate of cell motion. Specifically,\nwe find that a glass-like regime with caging behavior indicated by subdiffusive\ncell displacements can be achieved in systems with sufficiently low rates of\ncell cycling."
    },
    {
        "anchor": "Density anomaly in water-alcohol mixtures: minimum model for structure\n  makers and breakers: We modeled the change in the temperature of maximum density (TMD) of a\nwater-like solvent when small amounts of solute are added to the mixture. The\nsolvent is modeled as a two length scales potential, which is known to exhibit\nwater-like characteristic anomalies, while the solute is chosen to have an\nattractive interaction with the solvent which is tuned from small to large\nattractive potential. We show that if the solute exhibits high attraction with\nthe solvent it behaves as a structure maker and the TMD increases with the\naddition of solute, while if the solute shows a low attraction with the solvent\nthe TMD decreases, with the solute behaving as a structure breaker.",
        "positive": "Anomalous increase in nematic-isotropic transition temperature in dimer\n  molecules induced by magnetic field: We have determined the nematic-isotropic transition temperature as a function\nof applied magnetic field in three different thermotropic liquid crystalline\ndimers. These molecules are comprised of two rigid calamitic moieties joined\nend to end by flexible spacers with odd numbers of methylene groups. They show\nan unprecedented magnetic field enhancement of nematic order in that the\ntransition temperature is increased by up to 15K when subjected to 22T magnetic\nfield. The increase is conjectured to be caused by a magnetic field-induced\ndecrease of the average bend angle in the aliphatic spacers connecting the\nrigid mesogenic units of the dimers."
    },
    {
        "anchor": "Experimental evidence of detailed balance in granular systems: The principle of detailed balance (DB) states that every kinetic transition\nin a system with many micro-states, $\\mu$, is balanced, on average, with the\nopposite transition, $\\mu_i\\leftrightharpoons\\mu_j$. Since its introduction by\nBoltzmann, this principle has been used by luminaries, such as Einstein,\nEddington, Kramers, Pauli, Ehrenfest, Dirac, Onsager, and many others to derive\nsignificant results that underpin much of our scientific understanding. The\ncurrent belief is that DB is satisfied only in equilibrium systems, while\nnon-equilibrium steady states can only be balanced by cycles, such as $A\\to\nB\\to C\\to A$. We show here experimentally that DB can exist and is commonly and\nrobustly satisfied in a family of quasi-statically cyclically sheared granular\nsystems. We further study the approach to DB as a function of system size and\ntime. Given the significant impact that this principle has had on equilibrium\nsystems, we believe that this discovery paves the way for better models of the\ndynamics of non-equilibrium systems.",
        "positive": "Heat capacity of liquids: A hydrodynamic approach: We study autocorrelation functions of energy, heat and entropy densities\nobtained by molecular dynamics simulations of supercritical Ar and compare them\nwith the predictions of the hydrodynamic theory. It is shown that the predicted\nby the hydrodynamic theory single-exponential shape of the entropy density\nautocorrelation functions is perfectly reproduced for small wave numbers by the\nmolecular dynamics simulations and permits the calculation of the\nwavenumber-dependent specific heat at constant pressure. The estimated\nwavenumber-dependent specific heats at constant volume and pressure, $C_{v}(k)$\nand $C_{p}(k)$, are shown to be in the long-wavelength limit in good agreement\nwith the macroscopic experimental values of $C_{v}$ and $C_{p}$ for the studied\nthermodynamic points of supercritical Ar."
    },
    {
        "anchor": "Inhomogeneous Relaxation Dynamics and Phase Behaviour of a Liquid\n  Crystal Confined in a Nanoporous Solid: We report filling-fraction dependent dielectric spectroscopy measurements on\nthe relaxation dynamics of the rod-like nematogen 7CB condensed in 13 nm silica\nnanochannels. In the film-condensed regime, a slow interface relaxation\ndominates the dielectric spectra, whereas from the capillary-condensed state up\nto complete filling an additional, fast relaxation in the core of the channels\nis found. The temperature-dependence of the static capacitance, representative\nof the averaged, collective molecular orientational ordering, indicates a\ncontinuous, paranematic-to-nematic (P-N) transition, in contrast to the\ndiscontinuous bulk behaviour. It is well described by a Landau-de-Gennes free\nenergy model for a phase transition in cylindrical confinement. The large\ntensile pressure of 10 MPa in the capillary-condensed state, resulting from the\nYoung-Laplace pressure at highly curved liquid menisci, quantitatively accounts\nfor a downward-shift of the P-N transition and an increased molecular mobility\nin comparison to the unstretched liquid state of the complete filling. The\nstrengths of the slow and fast relaxations provide local information on the\norientational order: The thermotropic behaviour in the core region is\nbulk-like, i.e. it is characterized by an abrupt onset of the nematic order at\nthe P-N transition. By contrast, the interface ordering exhibits a continuous\nevolution at the P-N transition. Thus, the phase behaviour of the entirely\nfilled liquid crystal-silica nanocomposite can be quantitatively described by a\nlinear superposition of these distinct nematic order contributions.",
        "positive": "Supercooled Lennard-Jones Liquids and Glasses: a Kinetic Monte Carlo\n  Approach: A kinetic Monte Carlo (KMC) method is used to study the structural properties\nand dynamics of a supercooled binary Lennard-Jones liquid around the glass\ntransition temperature. This technique permits us to explore the potential\nenergy surface and barrier distributions without suffering the exponential\nslowing down at low temperature that affects molecular dynamics simulations. In\nagreement with previous studies we observe a distinct change in behaviour\naround $T=0.45$, close to the dynamical transition temperature $T_c$ of mode\ncoupling theory (MCT). Below this temperature the number of different local\nminima visited by the system for the same number of KMC steps decreases by more\nthan an order of magnitude. The mean number of atoms involved in each jump\nbetween local minima and the average distance they move also decreases\nsignificantly, and new features appear in the partial structure factor. Above\n$T~0.45$ the probability distribution for the magnitude of the atomic\ndisplacement per KMC step exhibits an exponential decay, which is only weakly\ntemperature dependent."
    },
    {
        "anchor": "Strain-Rate Frequency Superposition in Large-Amplitude Oscillatory Shear: In a recent work, Wyss, {\\it et.al.} [Phys. Rev. Lett., {\\bf 98}, 238303\n(2007)] have noted a property of `soft solids' under oscillatory shear, the\nso-called strain-rate frequency superposition (SRFS). We extend this study to\nthe case of soft solids under large-amplitude oscillatory shear (LAOS). We show\nresults from LAOS studies in a monodisperse hydrogel suspension, an aqueous\ngel, and a biopolymer suspension, and show that constant strain-rate frequency\nsweep measurements with soft solids can be superimposed onto master curves for\nhigher harmonic moduli, with the {\\it same} shift factors as for the linear\nviscoelastic moduli. We show that the behavior of higher harmonic moduli at low\nfrequencies in constant strain-rate frequency sweep measurements is similar to\nthat at large strain amplitudes in strain-amplitude sweep tests. We show\nsurface plots of the harmonic moduli and the energy dissipation rate per unit\nvolume in LAOS for soft solids, and show experimentally that the energy\ndissipated per unit volume depends on the first harmonic loss modulus alone, in\nboth the linear and the nonlinear viscoelastic regime.",
        "positive": "Is superhydrophobicity robust with respect to disorder?: We consider theoretically the Cassie-Baxter and Wenzel states describing the\nwetting contact angles for rough substrates. More precisely, we consider\ndifferent types of periodic geometries such as square protrusions and disks in\n2D, grooves and nanoparticles in 3D and derive explicitly the contact angle\nformulas. We also show how to introduce the concept of surface disorder within\nthe problem and, inspired by biomimetism, study its effect on\nsuperhydrophobicity. Our results, quite generally, prove that introducing\ndisorder, at fixed given roughness, will lower the contact angle: a disordered\nsubstrate will have a lower contact angle than a corresponding periodic\nsubstrate. We also show that there are some choices of disorder for which the\nloss of superhydrophobicity can be made small, making superhydrophobicity\nrobust."
    },
    {
        "anchor": "Wall slip across the jamming transition of soft thermoresponsive\n  particles: Flows of suspensions are often affected by wall slip, that is the fluid\nvelocity $v_{f}$ in the vicinity of a boundary differs from the wall velocity\n$v_{w}$ due to the presence of a lubrication layer. While the slip velocity\n$v_s=\\vert v_{f}-v_{w}\\vert$ robustly scales linearly with the stress $\\sigma$\nat the wall in dilute suspensions, there is no consensus regarding denser\nsuspensions that are sheared in the bulk, for which slip velocities have been\nreported to scale as a $v_s\\propto\\sigma^p$ with exponents $p$ inconsistently\nranging between 0 and 2. Here we focus on a suspension of soft thermoresponsive\nparticles and show that $v_s$ actually scales as a power law of the viscous\nstress $\\sigma-\\sigma_c$, where $\\sigma_c$ denotes the yield stress of the bulk\nmaterial. By tuning the temperature across the jamming transition, we further\ndemonstrate that this scaling holds true over a large range of packing\nfractions $\\phi$ on both sides of the jamming point and that the exponent $p$\nincreases continuously with $\\phi$, from $p=1$ in the case of dilute\nsuspensions to $p=2$ for jammed assemblies. These results allow us to\nsuccessfully revisit inconsistent data from the literature and paves the way\nfor a continuous description of wall slip above and below jamming.",
        "positive": "Optimal control of interacting active particles on complex landscapes: Active many-body systems composed of many interacting degrees of freedom\noften operate out of equilibrium, giving rise to non-trivial emergent behaviors\nwhich can be functional in both evolved and engineered contexts. This naturally\nsuggests the question of control to optimize function. Using navigation as a\nparadigm for function, we deploy the language of stochastic optimal control\ntheory to formulate the inverse problem of shepherding a system of interacting\nactive particles across a complex landscape. We implement a solution to this\nhigh-dimensional problem using an Adjoint-based Path Integral Control (APIC)\nalgorithm that combines the power of recently introduced continuous-time\nback-propagation methods and automatic differentiation with the classical\nFeynman-Kac path integral formulation in statistical mechanics. Numerical\nexperiments for controlling individual and interacting particles in complex\nlandscapes show different classes of successful navigation strategies as a\nfunction of landscape complexity, as well as the intrinsic noise and drive of\nthe active particles. However, in all cases, we see the emergence of paths that\ncorrespond to traversal along the edges of ridges and ravines, which we can\nunderstand using a variational analysis. We also show that the work associated\nwith optimal strategies is inversely proportional to the length of the time\nhorizon of optimal control, a result that follows from scaling considerations.\nAll together, our approach serves as a foundational framework to control active\nnon-equilibrium systems optimally to achieve functionality, embodied as a path\non a high-dimensional manifold."
    },
    {
        "anchor": "Theoretical and experimental study of the stability of a soap film\n  spanning a flexible loop: A variational model is used to study the stability of a soap film spanning a\nflexible loop. The film is modeled as a fluid surface endowed with constant\ntension and the loop is modeled as an elastic rod resistant to both bending and\ntwist. The first and second energy variations of the underlying energy\nfunctional are derived, leading to governing equilibrium equations and\nstability criteria. The latter criteria are employed to explore the stability\nof flat circular configurations with respect to planar and transverse\nperturbations. Experiments are performed to study post-buckled configurations\nand to explore the validity of the theoretical predictions. Imparting a twist\nto the bounding loop destabilizes flat circular loops which are short-enough to\nbe stable when twist-free. Nevertheless, when the circular disk is perturbed\nmerely radially or merely transversely, the stability condition is indifferent\nto twist. By the equilibrium equations, the twisting angle of a planar\nequilibrium configuration should be distributed uniformly along the loop. The\nstability criteria guarantee that this uniformity is preserved after buckling.\nThe stability with respect to increasing the surface tension of the film or the\nlength of the loop is sensitive to the cross-sectional thickness of the\nbounding loop. However, stability with respect to increasing the total twist is\nindifferent to that thickness.",
        "positive": "Nanoscale Seebeck effect at hot metal nanostructures: We theoretically study the electrolyte Seebeck effect in the vicinity of a\nheated metal nanostructure, such as the cap of an active Janus colloid in an\nelectrolyte, or gold- coated interfaces in optofluidic devices. The\nthermocharge accumulated at the surface varies with the local temperature, thus\nmodulating the diffuse part of the electric double layer. On a conducting\nsurface with non-uniform temperature, the isopotential condition imposes a\nsignificant polarization charge within the metal. Surprisingly, this does not\naffect the slip velocity, which takes the same value on insulating and\nconducting surfaces. Our results for specific-ion effects agree qualitatively\nwith recent observations for Janus colloids in different electrolyte solutions.\nComparing the thermal, hydrodynamic, and ion diffusion time scales, we expect a\nrich transient behavior at the onset of thermally powered swimming, extending\nto microseconds after switching on the heating."
    },
    {
        "anchor": "A Twist On Active Membranes: Odd Mechanics, Spontaneous Flows and Shape\n  Instabilities: Living systems are chiral on multiple scales, from constituent biopolymers to\nlarge scale morphology, and their active mechanics is both driven by chiral\ncomponents and serves to generate chiral morphologies. We describe the\nmechanics of active fluid membranes in coordinate-free form, with focus on\nchiral contributions to the stress. These generate geometric `odd elastic'\nforces in response to mean curvature gradients but directed perpendicularly. As\na result, they induce tangential membrane flows that circulate around maxima\nand minima of membrane curvature. When the normal viscous force amplifies\nperturbations the membrane shape can become linearly unstable giving rise to\nshape instabilities controlled by an active Scriven-Love number. We describe\nexamples for spheroids, membranes tubes and helicoids, discussing the relevance\nand predictions such examples make for a variety of biological systems from the\nsub-cellular to tissue level.",
        "positive": "Stick-Slip Sliding of Water Drops on Chemically Heterogeneous Surfaces: We present a comprehensive study of water drops sliding down chemically\nheterogeneous surfaces formed by a periodic pattern of alternating hydrophobic\nand hydrophilic stripes. Drops are found to undergo a stick-slip motion whose\naverage speed is an order of magnitude smaller than that measured on a\nhomogeneous surface having the same static contact angle. This motion is the\nresult of the periodic deformations of the drop interface when crossing the\nstripes. Numerical simulations confirm this view and are used to elucidate the\nprinciples underlying the experimental observations."
    },
    {
        "anchor": "Modeling Equilibrium Clusters in Lysozyme Solutions: We present a combined experimental and numerical study of the equilibrium\ncluster formation in globular protein solutions under no-added salt conditions.\nWe show that a cluster phase emerges as a result of a competition between a\nlong-range screened Coulomb repulsion and a short-range attraction. A simple\neffective potential, in which only depth and width of the attractive part of\nthe potential are optimized, accounts in a remarkable way for the wavevector\ndependence of the X-ray scattering structure factor.",
        "positive": "Rings in Random Environments: Sensing Disorder Through Topology: In this paper we study the role of topology in DNA gel electrophoresis\nexperiments via molecular dynamics simulations. The gel is modelled as a 3D\narray of obstacles from which half edges are removed at random with probability\np, thereby generating a disordered environment. Changes in the microscopic\nstructure of the gel are captured by measuring the electrophoretic mobility of\nring polymers moving through the medium, while their linear counterparts\nprovide a control system as we show they are insensitive to these changes. We\nshow that ring polymers provide a novel non-invasive way of exploiting topology\nto sense microscopic disorder. Finally, we compare the results from the\nsimulations with an analytical model for the non-equilibrium differential\nmobility, and find a striking agreement between simulation and theory"
    },
    {
        "anchor": "Dynamical Behaviour of Fine Granular Glass/Bronze Mixtures under\n  Vertical Vibration: We report the behaviour of mixtures of fine bronze and glass spheres under\nsinusoidal vertical vibration. Depending upon the ratio of their diameters and\nthe amplitude and frequency of the vibration, we observe the formation of sharp\nseparation boundaries between glass-rich and bronze-rich phases, the absence of\ngross convection which would mix these phases, and a number of oscillatory and\nnon-periodic behaviours. These phenomena are related to the differential air\ndamping of the glass and bronze grains, disappearing completely in the absence\nof air.",
        "positive": "DEM simulation of the powder application in powder bed fusion: The packing behavior of powders is significantly influenced by various types\nof inter-particle attractive forces, including adhesion and non-bonded van der\nWaals forces [1, 2, 3, 4, 5, 6]. Alongside particle size and shape\ndistributions, the inter-particle interactions, in particular frictional and\nadhesive forces, play a crucial role in determining the flow behavior and\nconsequently the packing density of the powder layer. The impact of various\ntypes of attractive forces on the packing density of powders with different\nmaterials and particle size distributions remains largely unexplored and\nrequires further investigation. Accurately comprehending these effects through\nexperiments while considering specific particle size distributions and material\nproperties poses significant challenges. To address these challenges, we employ\nDiscrete Element Method (DEM) simulations to characterize the packing behavior\nof fine powders. We can demonstrate quantitative agreement with experimental\nresults by incorporating the appropriate particle size distribution and using\nan adequate model of attractive particle interactions. Furthermore, our\nfindings indicate that both adhesion, which is modeled using the\nJohnson-Kendall-Roberts (JKR) model [7], and van der Waals interactions are\ncrucial factors that must be taken into account in DEM simulations."
    },
    {
        "anchor": "Driven polymer translocation into a channel: Iso-flux tension\n  propagation theory and Langevin dynamics simulations: Iso-flux tension propagation (IFTP) theory and Langevin dynamics (LD)\nsimulations are employed to study the dynamics of channel-driven polymer\ntranslocation in which a polymer translocates into a narrow channel and the\nmonomers in the channel experience a driving force $f_{\\rm c}$. In the high\ndriving force limit, regardless of the channel width, IFTP theory predicts\n$\\tau\\propto f_{\\textrm{c}}^{\\beta}$ for the translocation time, where\n$\\beta=-1$ is the force scaling exponent. Moreover, LD data show that for a\nvery narrow channel fitting only a single file of monomers, the entropic force\ndue to the subchain inside the channel does not play a significant role in the\ntranslocation dynamics, and the force exponent $\\beta= -1$ regardless of the\nforce magnitude. As the channel width increases the number of possible spatial\nconfigurations of the subchain inside the channel becomes significant, and the\nresulting entropic force causes the force exponent to drop below unity.",
        "positive": "Following your nose: Autochemotaxis and other mechanisms for spinodal\n  decomposition in flocks: We develop the hydrodynamic theory of dry, polar ordered, active matter\n(``flocking\") with autochemotaxis; i.e., self-propelled entities moving in the\nsame direction, each emitting a substance which attracts the others (e.g.,\nants). We find that sufficiently strong autochemotaxis leads to an instability\nto phase separation into one high and one low density band. This is very\nanalogous to both equilibrium phase separation, and ``motility induced phase\nseparation\" (``MIPS\") and can occur in flocks due to any microscopic mechanism\n(e.g., sufficiently strong attractive interactions) that makes the entities\ncohere."
    },
    {
        "anchor": "Collective modes of trapped gases at the BEC-BCS crossover: The collective mode frequencies in isotropic and deformed traps are\ncalculated for general polytropic equation of states, $P\\propto n^{\\gamma+1}$,\nand expressed in terms of $\\gamma$ and the trap geometry. For molecular and\nstandard Bose-Einstein condensates and Fermi gases near Feshbach resonances,\nthe effective power $\\gamma\\simeq0.5-1.3$ is calculated from Jastrow type\nwave-function ans\\\"atze, and from the crossover model of Leggett. The resulting\nmode frequencies are calculated for these phases around the BCS-BEC crossover.",
        "positive": "The effect of active fluctuations on the dynamics of particles, motors\n  and hairpins: Inspired by recent experiments on the dynamics of particles and polymers in\nartificial cytoskeletons and in cells, we introduce a modified Langevin\nequation for a particle in an environment that is a viscoelastic medium and\nthat is brought out of equilibrium by the action of active fluctuations caused\nby molecular motors. We show that within such a model, the motion of a free\nparticle crosses over from superdiffusive to subdiffusive as observed for\ntracer particles in an {\\it in vitro} cytoskeleton or in a cell. We investigate\nthe dynamics of a particle confined by a harmonic potential as a simple model\nfor the motion of the tethered head of kinesin-1. We find that the probability\nthat the head is close to its binding site on the microtubule can be enhanced\nby a factor of two due to active forces. Finally, we study the dynamics of a\nparticle in a double well potential as a model for the dynamics of\nDNA-hairpins. We show that the active forces effectively lower the potential\nbarrier between the two minima and study the impact of this phenomenon on the\nzipping/unzipping rate."
    },
    {
        "anchor": "Screening in Ionic Systems: Simulations for the Lebowitz Length: Simulations of the Lebowitz length, $\\xi_{\\text{L}}(T,\\rho)$, are reported\nfor t he restricted primitive model hard-core (diameter $a$) 1:1 electrolyte\nfor densi ties $\\rho\\lesssim 4\\rho_c$ and $T_c \\lesssim T \\lesssim 40T_c$.\nFinite-size eff ects are elucidated for the charge fluctuations in various\nsubdomains that serve to evaluate $\\xi_{\\text{L}}$. On extrapolation to the\nbulk limit for $T\\gtrsim 10T_c$ the low-density expansions (Bekiranov and\nFisher, 1998) are seen to fail badly when $\\rho > {1/10}\\rho_c$ (with $\\rho_c\na^3 \\simeq 0.08$). At highe r densities $\\xi_{\\text{L}}$ rises above the Debye\nlength, $\\xi_{\\text{D}} \\prop to \\sqrt{T/\\rho}$, by 10-30% (upto $\\rho\\simeq\n1.3\\rho_c$); the variation is portrayed fairly well by generalized\nDebye-H\\\"{u}ckel theory (Lee and Fisher, 19 96). On approaching criticality at\nfixed $\\rho$ or fixed $T$, $\\xi_{\\text{L}}(T, \\rho)$ remains finite with\n$\\xi_{\\text{L}}^c \\simeq 0.30 a \\simeq 1.3 \\xi_{\\text {D}}^c$ but displays a\nweak entropy-like singularity.",
        "positive": "Nontrivial electrophoresis of silica micro and nanorods in a nematic\n  liquid crystal: We study DC and AC electrophoresis of silica micro and nanorods in a thin\nfilm of a nematic liquid crystal. These particles induce virtual topological\ndefects and also demonstrate nontrivial electrophoresis in a nematic liquid\ncrystal. We measure several nonlinear electrophoretic mobility coefficients and\ncompare with those calculated theoretically. We demonstrate a competing effect\nof the elastic and electrostatic torques that arises due to tilting of the rods\nwith respect to the liquid crystal director. A basic theory describing this\neffect allows us to measure the effective polarizability of the rods. Our\napproach is simple and applicable to a wide variety of asymmetric and\npolarizable particles."
    },
    {
        "anchor": "Statistical Mechanics of Membrane Protein Conformation: A Homopolymer\n  Model: The conformation and the phase diagram of a membrane protein are investigated\nvia grand canonical ensemble approach using a homopolymer model. We discuss the\nnature and pathway of $\\alpha$-helix integration into the membrane that results\ndepending upon membrane permeability and polymer adsorptivity. For a membrane\nwith the permeability larger than a critical value, the integration becomes the\nsecond order transition that occurs at the same temperature as that of the\nadsorption transition. For a nonadsorbing membrane, the integration is of the\nfirst order due to the aggregation of $\\alpha$-helices.",
        "positive": "Polydisperse hard spheres: Crystallization kinetics in small systems and\n  role of local structure: We study numerically the crystallization of a hard-sphere mixture with 8\\%\npolydispersity. Although often used as a model glass former, for small system\nsizes we observe crystallization in molecular dynamics simulations. This opens\nthe possibility to study the competition between crystallization and structural\nrelaxation of the melt, which typically is out of reach due to the disparate\ntimescales. We quantify the dependence of relaxation and crystallization times\non density and system size. For one density and system size we perform a\ndetailed committor analysis to investigate the suitability of local structures\nas order parameters to describe the crystallization process. We find that local\nstructures are strongly correlated with generic bond order and add little\ninformation to the reaction coordinate."
    },
    {
        "anchor": "Homogeneous Alignment of Liquid Crystalline Dendrimers Confined in a\n  Slit-Pore: Computational Simulation Study: In this work we present results from NPT(isobaric-isothermal) Monte Carlo\nSimulation studies of Liquid Crystalline Dendrimer (LCDr) systems confined in a\nslit-pore made of two parallel flat walls. We investigate the substrate induced\nconformational and alignment properties of the system at different\nthermodynamic state points under uniform (unidirectional) anchoring condition.\nTractable coarse grained force fields to model both monomer-monomer and\nmonomer-substrate interaction potentials have been used from our previous work.\nIn this anchoring condition, at lower pressure almost all the monomers are\nanchored to the substrates and mesogens are perfectly aligned with the aligning\ndirection. This alignment is not uniformly transmitted to the bulk region as\nthe pressure grows, instead, it decays with distance from the surface to the\nbulk region. Due to this reason, the global orintational order parameter\ndecreases with increasing pressure (density). In the neighborhood (2-3\nmesogenic diameter) of upper and lower walls, mesogenic units form smectic A\nlike structure whose layers are separated by layers of spherical beads. In this\nregion individual LCDrs possess a rod like shape.",
        "positive": "Modelling of artefacts in estimations of particle size of needle-like\n  particles from laser diffraction measurements: Manufacturing of particulate products across many industries relies on\naccurate measurements of particle size distributions in dispersions or powders.\nLaser diffraction (or small angle light scattering) is commonly used, usually\noff-line, for particle size measurements. The estimation of particle sizes by\nthis method requires the solution of an inverse problem using a suitable\nscattering model that takes into account size, shape and optical properties of\nthe particles. However, laser diffraction instruments are usually accompanied\nby software that employs a default scattering model for spherical particles,\nwhich is then used to solve the inverse problem even though a significant\nnumber of particulate products occur in strongly non-spherical shapes such as\nneedles. In this work, we demonstrate that using the spherical model for the\nestimation of sizes of needle-like particles can lead to the appearance of\nartefacts in the form of multimodal populations of particles with size modes\nmuch smaller than those actually present in the sample. This effect can result\nin a significant under-estimation of the mean particle size and in false modes\nin estimated particles size distributions."
    },
    {
        "anchor": "Spatiotemporal order and emergent edge currents in active spinner\n  materials: Collections of interacting, self-propelled particles have been extensively\nstudied as minimal models of many living and synthetic systems from bird flocks\nto active colloids. However, the influence of active rotations in the absence\nof self-propulsion i.e. spinning without walking) remains less explored. Here,\nwe numerically and theoretically investigate the behaviour of ensembles of\nself-spinning dimers. We find that geometric frustration of dimer rotation by\ninteractions yields spatiotemporal order and active melting with no equilibrium\ncounterparts. At low density, the spinning dimers self-assemble into a\ntriangular lattice with their orientations phase-locked into spatially periodic\nphases. The phase-locked patterns form dynamical analogues of the ground states\nof various spin models, transitioning from the 3-state Potts antiferromagnet at\nlow densities to the striped herringbone phase of planar quadrupoles at higher\ndensities. As the density is raised further, the competition between active\nrotations and interactions leads to melting of the active spinner crystal.\nEmergent edge currents, whose direction is set by the chirality of the active\nspinning, arise as a non-equilibrium signature of the transition to the active\nspinner liquid and vanish when the system eventually undergoes kinetic arrest\nat very high densities. Our findings may be realized in systems ranging from\nliquid crystal and colloidal experiments to tabletop realizations using\nmacroscopic chiral grains.",
        "positive": "Polarisation-driven magneto-optical and nonlinear-optical behaviour of a\n  room-temperature ferroelectric nematic phase: Nematics with a broken polar symmetry is one of the fascinating recent\ndiscoveries in the field of soft matter. High spontaneous polarisation and the\nfluidity of the ferroelectric nematic $N_{\\mathrm{F}}$ phase make such\nmaterials attractive for future applications and interesting for fundamental\nresearch. Here we explore the polar and mechanical properties of a\nroom-temperature ferroelectric nematic and its behaviour in a magnetic field.\nWe show that $N_{\\mathrm{F}}$ is much less susceptible to the splay deformation\nthan to the twist. The strong splay rigidity can be attributed to the\nelectrostatic self-interaction of the polarisation avoiding the polarisation\nsplay."
    },
    {
        "anchor": "Kinetics of transfer of volatile amphiphiles (fragrances) from vapors to\n  aqueous drops and vice versa: Interplay of diffusion and barrier mechanisms: Subject of this work is to investigate the kinetics of mass transfer of\nvolatile amphiphiles from their vapors to aqueous drops, and from the saturated\naqueous drop solutions to air. The used amphiphiles are benzyl acetate,\nlinalool, and citronellol. The adequate theoretical processing of the\nequilibrium surface tension isotherms is applied to construct the\ntwo-dimensional equation of state, which relates the surface tension to the\nadsorption at the interface. The measured surface tension relaxations with time\nin the regimes of adsorption from vapor and evaporation from drop combined with\nthe equations of state provide quantitative information on the change of\nadsorption because of the volatile amphiphile mass transfer across the surface.\nThe theoretical analysis of the diffusion and barrier mechanisms in the case of\nadsorption from vapor to the aqueous drop shows that the mixed\nbarrier-diffusion control in the vapor and diffusion control in the drop\ndescribe experimental data. The obtained values of the adsorption rate\nconstants are six orders of magnitude larger than those for hexane and\ncyclohexane reported in the literature. The regime of evaporation from aqueous\namphiphile solution drop follows the convection-enhanced adsorption mechanism\nwith desorption rate constant in the vapor affected by the simultaneous water\nevaporation and amphiphile desorption. The water evaporation suppresses the\nevaporation of linalool and accelerates desorption of benzyl acetate and\ncitronellol. From viewpoint of applications, the obtained physicochemical\nparameters of the studied three fragrances can help for better understanding of\ntheir performance in shampoo systems and perfumes. From theoretical viewpoint,\nthe result show that by introducing an effective amphiphile desorption rate\nconstant it is possible to quantify the complex volatile amphiphile desorption\naccompanied with the water evaporation.",
        "positive": "Radial Distribution Function for Semiflexible Polymers Confined in\n  Microchannels: An analytic expression is derived for the distribution $G(\\vec{R})$ of the\nend-to-end distance $\\vec{R}$ of semiflexible polymers in external potentials\nto elucidate the effect of confinement on the mechanical and statistical\nproperties of biomolecules. For parabolic confinement the result is exact\nwhereas for realistic potentials a self-consistent ansatz is developed, so that\n$G(\\vec{R})$ is given explicitly even for hard wall confinement. The\ntheoretical result is in excellent quantitative agreement with fluorescence\nmicroscopy data for actin filaments confined in rectangularly shaped\nmicrochannels. This allows an unambiguous determination of persistence length\n$L_P$ and the dependence of statistical properties such as Odijk's deflection\nlength $\\lambda$ on the channel width $D$. It is shown that neglecting the\neffect of confinement leads to a significant overestimation of bending\nrigidities for filaments."
    },
    {
        "anchor": "Lateral and normal forces between patterned substrates induced by\n  nematic fluctuations: We consider a nematic liquid crystal confined by two parallel flat substrates\nwhose anchoring conditions vary periodically in one lateral direction. Within\nthe Gaussian approximation, we study the effective forces between the patterned\nsubstrates induced by the thermal fluctuations of the nematic director. The\nshear force oscillates as function of the lateral shift between the patterns on\nthe lower and the upper substrates. We compare the strength of this\nfluctuation-induced lateral force with the lateral van der Waals force arising\nfrom chemically structured adsorbed monolayers. The fluctuation-induced force\nin normal direction is either repulsive or attractive, depending on the model\nparameters.",
        "positive": "Dynamics of a period-three pattern loaded Bose-Einstein condensate in an\n  optical lattice: We discuss the dynamics of a Bose-Einstein condensate initially loaded into\nevery third site of an optical lattice using a description based upon the\ndiscrete nonlinear Schrodinger equation. An analytic solution is developed for\nthe case of a periodic initial condition and is compared with numerical\nsimulations for more general initial configurations.\n  We show that mean field effects in this system can cause macroscopic quantum\nself-trapping, a phenomenon already predicted for double well systems. In the\npresence of a uniform external potential, the atoms exhibit generalized Bloch\noscillations which can be interpreted in terms of the interference of three\ndifferent Bloch states. We also discuss how the momentum distribution of the\nsystem can be used as experimental signature of the macroscopic self trapping\neffect."
    },
    {
        "anchor": "Local determination of the constitutive law of a dense suspension of\n  non-colloidal particles through MRI: We investigate the flowing behavior of dense suspensions of non-colloidal\nparticles, by coupling macroscopic rheometric experiments and local velocity\nand concentration measurements through MRI techniques. We find that the flow is\nlocalized at low velocities, and that the material is inhomogeneous; the local\nlaws inferred from macroscopic rheometric observations must then be\nreinterpreted in the light of these local observations. We show that the short\ntime response to a velocity step allows to characterize dense suspensions\nlocally: they have a purely viscous behavior, without any observable influence\nof friction. In the jammed zone, there may be a contact network, whereas in the\nsheared zone there are only hydrodynamic interactions: localization consists in\na change in configuration at the grain scale. From the concentration and\nvelocity profiles, we have provided for the first time local measurements of\nthe concentration dependence of viscosity; we find a Krieger-Dougherty law\n$\\eta(\\phi)=\\eta_0(1-\\phi/0.605)^{-2}$. Shear induced migration is almost\ninstantaneous and seems inconsistent with most observations: it would imply\nthat the diffusion coefficients strongly depend on the concentration. We\nfinally propose a simple constitutive law for dense suspensions, based on a\npurely viscous behavior, that accounts for all the macroscopic and local\nobservations.",
        "positive": "Accelerated simulation method for charge regulation effects: The net charge of solvated entities, ranging from polyelectrolytes and\nbiomolecules to charged nanoparticles and membranes, depends on the local\ndissociation equilibrium of individual ionizable groups. Incorporation of this\nphenomenon, \\emph{charge regulation}, in theoretical and computational models\nrequires dynamic, configuration-dependent recalculation of surface charges and\nis therefore typically approximated by assuming constant net charge on\nparticles. Various computational methods exist that address this. We present an\nalternative, particularly efficient charge regulation Monte Carlo method\n(CR-MC), which explicitly models the redistribution of individual charges and\naccurately samples the correct grand-canonical charge distribution. In\naddition, we provide an open-source implementation in the LAMMPS molecular\ndynamics (MD) simulation package, resulting in a hybrid MD/CR-MC simulation\nmethod. This implementation is designed to handle a wide range of\nimplicit-solvent systems that model discreet ionizable groups or surface sites.\nThe computational cost of the method scales linearly with the number of\nionizable groups, thereby allowing accurate simulations of systems containing\nthousands of individual ionizable sites. By matter of illustration, we use the\nCR-MC method to quantify the effects of charge regulation on the nature of the\npolyelectrolyte coil--globule transition and on the effective interaction\nbetween oppositely charged nanoparticles."
    },
    {
        "anchor": "Proportional Paths, Barodesy, and Granular Solid Hydrodynamics: Propotional paths as summed up by the Goldscheider Rule (GR) -- stating that\ngiven a constant strain rate, the evolution of the stress maintains the ratios\nof its components -- is a characteristics of elasto-plastic motion in granular\nmedia. Barodesy, a constitutive relation proposed recently by Kolymbas, is a\nmodel that, with GR as input, successfully accounts for data from soil\nmechanical experiments. Granular solid hydrodynamics (GSH), a theory derived\nfrom general principles of physics and two assumptions about the basic behavior\nof granular media, is constructed to qualitatively account for a wide range of\nobservation -- from elastic waves over elasto-plastic motion to rapid dense\nflow. In this paper, showing the close resemblance of results from Barodesy and\nGSH, we further validate GSH and provide an understanding for GR.",
        "positive": "Study of Active Brownian Particle Diffusion in Polymer Solutions: The diffusion behavior of an active Brownian particle (ABP) in polymer\nsolutions is studied using Langevin dynamics simulations. We find that the long\ntime diffusion coefficient $D$ can show a non-monotonic dependence on the\nparticle size $R$ if the active force $F_{a}$ is large enough, wherein a bigger\nparticle would diffuse faster than a smaller one which is quite\ncounterintuitive. By analyzing the short time dynamics in comparison to the\npassive one, we find that such non-trivial dependence results from the\ncompetition between persistence motion of the ABP and the length-scale\ndependent effective viscosity that the particle experienced in the polymer\nsolution. \\textcolor{black}{We have also introduced an effective viscosity\n$\\eta_{\\text{eff}}$ experienced by the ABP phenomenologically. Such an active\n$\\eta_{\\text{eff}}$ is found to be larger than a passive one and strongly\ndepends on $R$ and $F_{a}$}\\textcolor{magenta}{.} In addition, we find that the\ndependence of $D$ on propelling force $F_{a}$ presents a well scaling form at a\nfixed $R$ and the scaling factor changes non-monotonically with $R$. Such\nresults demonstrate that active issue plays rather subtle roles on the\ndiffusion of nano-particle in complex solutions."
    },
    {
        "anchor": "Hybrid simulations of lateral diffusion in fluctuating membranes: In this paper we introduce a novel method to simulate lateral diffusion of\ninclusions in a fluctuating membrane. The regarded systems are governed by two\ndynamic processes: the height fluctuations of the membrane and the diffusion of\nthe inclusion along the membrane. While membrane fluctuations can be expressed\nin terms of a dynamic equation which follows from the Helfrich Hamiltonian, the\ndynamics of the diffusing particle is described by a Langevin or Smoluchowski\nequation. In the latter equations, the curvature of the surface needs to be\naccounted for, which makes particle diffusion a function of membrane\nfluctuations. In our scheme these coupled dynamic equations, the membrane\nequation and the Langevin equation for the particle, are numerically integrated\nto simulate diffusion in a membrane. The simulations are used to study the\nratio of the diffusion coefficient projected on a flat plane and the\nintramembrane diffusion coefficient for the case of free diffusion. We compare\nour results with recent analytical results that employ a preaveraging\napproximation and analyze the validity of this approximation. A detailed\nsimulation study of the relevant correlation functions reveals a surprisingly\nlarge range where the approximation is applicable.",
        "positive": "Oscillations of atomic fermions in a one dimensional optical lattice: A semiclassical model is used to investigate oscillations of atomic fermions\nin a combined magnetic trap and one dimensional optical lattice potential\nfollowing axial displacement of the trap. The oscillations are shown to have a\ncharacteristic small amplitude, damped behavior in the collisionless regime.\nThe presence of a separatrix in the semiclassical Brillouin zone phase space is\npredicted and shown to produce a strongly asymmetric phase space distribution\nfunction."
    },
    {
        "anchor": "Hydrodynamics calculations of clusters of drops using the finite volume\n  method: In this paper is described a numerical scheme that is used to simulate the\ncoalescence process between clusters of water drops immersed in a continuous\nhydrocarbon phase (n-heptane). Two different values for the initial velocity of\nthe drops were chosen. Depending of the initial velocity of collision some\nscenarios emerge, such as: permanent coalescence, formation of satellite drops\netc. For some snap shots the streamlines are calculated for the different\nprocess of permanent coalescence. These streamlines allow the understanding of\nthe dynamics of the droplets immersed on the n-heptane phase.",
        "positive": "The pair potential of colloidal stars: We report on the construction of colloidal stars: 1 micrometer polystyrene\nbeads grafted with a dense brush of 1 micrometer long and 10 nm wide\nsemi-flexible filamentous viruses. The pair interaction potentials of colloidal\nstars are measured using an experimental implementation of umbrella sampling, a\ntechnique originally developed in computer simulations in order to probe rare\nevents. The influence of ionic strength and grafting density on the interaction\nis measured. Good agreements are found between the measured interactions and\ntheoretical predictions based upon the osmotic pressure of counterions."
    },
    {
        "anchor": "Point defects in two-dimensional colloidal crystals: simulation vs.\n  elasticity theory: Using numerical and analytical calculations we study the structure of\nvacancies and interstitials in two-dimensional colloidal crystals. In\nparticular, we compare the displacement fields of the defect obtained\nnumerically with the predictions of continuum elasticity theory for a simple\ndefect model. In such a comparison it is of crucial importance to employ\ncorresponding boundary conditions both in the particle and in the continuum\ncalculations. Here, we formulate the continuum problem in a way that makes it\nanalogous to the electrostatics problem of finding the potential of a point\ncharge in periodic boundary conditions. The continuum calculations can then be\ncarried out using the technique of Ewald summation. For interstitials, the\ndisplacement fields predicted by elasticity theory are accurate at large\ndistances, but large deviations occur near the defect for distances of up to 10\nlattice spacings. For vacancies, the elasticity theory predictions obtained for\nthe simple model do not reproduce the numerical results even far away from the\ndefect.",
        "positive": "Forced translocation of a polymer: dynamical scaling vs. MD-simulation: We suggest a theoretical description of the force-induced translocation\ndynamics of a polymer chain through a nanopore. Our consideration is based on\nthe tensile (Pincus) blob picture of a pulled chain and the notion of\npropagating front of tensile force along the chain backbone, suggested recently\nby T. Sakaue. The driving force is associated with a chemical potential\ngradient that acts on each chain segment inside the pore. Depending on its\nstrength, different regimes of polymer motion (named after the typical chain\nconformation, \"trumpet\", \"stem-trumpet\", etc.) occur. Assuming that the local\ndriving and drag forces are equal (i.e., in a quasi-static approximation), we\nderive an equation of motion for the tensile front position $X(t)$. We show\nthat the scaling law for the average translocation time $<\\tau>$ changes from\n$<\\tau> \\sim N^{2\\nu}/f^{1/\\nu}$ to $<\\tau> \\sim N^{1+\\nu}/f$ (for the\nfree-draining case) as the dimensionless force ${\\widetilde f}_{R} = a N^{\\nu}f\n/T$ (where $a$, $N$, $\\nu$, $f$, $T$ are the Kuhn segment length, the chain\nlength, the Flory exponent, the driving force, and the temperature,\nrespectively) increases. These and other predictions are tested by Molecular\nDynamics (MD) simulation. Data from our computer experiment indicates indeed\nthat the translocation scaling exponent $\\alpha$ grows with the pulling force\n${\\widetilde f}_{R}$) albeit the observed exponent $\\alpha$ stays\nsystematically smaller than the theoretically predicted value. This might be\nassociated with fluctuations which are neglected in the quasi-static\napproximation."
    },
    {
        "anchor": "Finite-amplitude inhomogeneous plane waves in a deformed Mooney-Rivlin\n  material: The propagation of finite-amplitude linearly-polarized inhomogeneous\ntransverse plane waves is considered for a Mooney-Rivlin material maintained in\na state of finite static homogeneous deformation. It is shown that such waves\nare possible provided that the directions of the normal to the planes of\nconstant phase and of the normal to the planes of constant amplitude are\northogonal and conjugate with respect to the B-ellipsoid, where B is the left\nCauchy-Green strain tensor corresponding to the initial deformation. For these\nwaves, it is found that even though the system is non-linear, results on energy\nflux are nevertheless identical with corresponding results in the classical\nlinearized elasticity theory. Byproducts of the results are new exact static\nsolutions for the Mooney-Rivlin material.",
        "positive": "Unexpectedly super strong paramagnetism of aromatic peptides due to\n  cations of divalent metals: The magnetism of most biological systems has not been characterized, which\ndirectly impedes our understanding of many magnetic field-related phenomena,\nincluding magnetoreception and magnetic bio-effects. Here we measured the\nmagnetic susceptibility of aromatic peptide AYFFF self-assemblies in the\npresence or absence of divalent metal cations in liquid phase at room\ntemperature. Unexpectedly, the magnetic susceptibilities of AYFFF\nself-assemblies in the chloride solution of various divalent cations (Mg2+,\nZn2+, and Cu2+) show super strong paramagnetism. We attribute the super strong\nparamagnetism to existence of the magnetic moments on the cations adsorbed on\naromatic rings in the AYFFF assemblies through hydrated cation-{\\pi}\ninteractions, where the adsorbed cations display non-divalent behavior with\nunpaired electron spins. Our results indicate the super strong paramagnetism or\npotential ferromagnetism in the aromatic ring-enriched biomolecules when there\nare enough cations of divalent metals adsorbed. The findings not only provide\nfundamental information for understanding the magnetism of biological systems,\nprovoke insights for investigating the origin of magnetoreception and\nbio-effects of magnetic fields, but also help developing future\nmagnetic-control techniques on aromatic ring-enriched biomolecules and drugs in\nliving organisms, as well as biomaterial fabrication and manipulation."
    },
    {
        "anchor": "Structure of polydisperse inverse ferrofluids: Theory and computer\n  simulation: By using theoretical analysis and molecular dynamics simulations, we\ninvestigate the structure of colloidal crystals formed by nonmagnetic\nmicroparticles (or magnetic holes) suspended in ferrofluids (called inverse\nferrofluids), by taking into account the effect of polydispersity in size of\nthe nonmagnetic microparticles. Such polydispersity often exists in real\nsituations. We obtain an analytical expression for the interaction energy of\nmonodisperse, bidisperse, and polydisperse inverse ferrofluids. Body-centered\ntetragonal (bct) lattices are shown to possess the lowest energy when compared\nwith other sorts of lattices and thus serve as the ground state of the systems.\nAlso, the effect of microparticle size distributions (namely, polydispersity in\nsize) plays an important role in the formation of various kinds of structural\nconfigurations. Thus, it seems possible to fabricate colloidal crystals by\nchoosing appropriate polydispersity in size.",
        "positive": "Is the Molecular Weight Dependence of the Glass Transition Temperature\n  Caused by a Chain End Effect?: The immense dependence of the glass transition temperature $T_g$ on molecular\nweight $M$ is one of the most fundamentally and practically important features\nof polymer glass formation. Here, we report on molecular dynamics simulation of\nthree model linear polymers of substantially different complexity demonstrating\nthat the 70-year-old canonical explanation of this dependence (a simple chain\nend dilution effect) is likely incorrect at leading order. Our data shows that\nend effects are present only in relatively stiff polymers and, furthermore,\nthat the magnitude of this end effect diminishes on cooling. Instead, we find\nthat $T_g(M)$ trends are instead dominated by shifts in $T_g$ throughout the\nentire polymer chain rather than through a chain end effect. We show that these\ndata are consistent with a generic two-barrier model of $T_g$ and its\n$M$-dependence, motivated by the Elastically Collective Nonlinear Langevin\nEquation (ECNLE) theory. More broadly, this work indicates both a need to\nreassess the canonical understanding of $T_g(M)$ in linear polymers (and\nmacromolecules at large) and an opportunity to reveal new glass formation\nphysics with renewed study of $M$ effects on $T_g$."
    },
    {
        "anchor": "Topological properties and shape of proliferative and non-proliferative\n  cell monolayers: During embryonic development, structures with complex geometry can emerge\nfrom planar epithelial monolayers and to study these shape transitions is of\nkey importance for revealing the biophysical laws involved in the morphogenesis\nof biological systems. Here, using the example of normal proliferative monkey\nkidney (COS) cell monolayers, we investigate global and local topological\ncharacteristics of this model system in dependence on its shape. The obtained\ndistributions of cells by their valence demonstrate a previously undetected\ndifference between the spherical and planar monolayers. In addition, in both\nspherical and planar monolayers, the probability to observe a pair of\nneighboring cells with certain valences depends on the topological charge of\nthe pair. The zero topological charge of the cell pair can increase the\nprobability for the cells to be the nearest neighbors. We then test and confirm\nthat analogous relationships take place in a more ordered spherical system with\na larger fraction of 6-valent cells, namely in the non-proliferative epithelium\n(follicular system) of ascidian species oocytes. However, unlike spherical COS\ncell monolayers, ascidian monolayers are prone to non-random agglomeration of\n6-valent cells and have linear topological defects called scars and pleats. The\nreasons for this difference in morphology are discussed. The morphological\npeculiarities found are compared with predictions of widely used vertex model\nof epithelium.",
        "positive": "Many-Body Force and Mobility Measurements in Colloidal Systems: We demonstrate a technique for simultaneously measuring each component of the\nforce vectors and mobility tensor of a small collection of colloidal particles\nbased on observing a set of particle trajectories. For a few-body system of\nmicron-sized polymer beads in oil separated by several particle radii, we find\nthat the mobility tensor is well-described by a pairwise Stokeslet model. This\nstands in contrast to the electrostatic interactions, which were found to\ndeviate significantly from a pairwise model. The measurement technique\npresented here should be simple to extend to systems of heterogeneous,\nnon-spherical particles arranged in arbitrary 3D geometries."
    },
    {
        "anchor": "Spontaneous Phase Separation of Ternary Fluid Mixtures: We computationally study the spontaneous phase separation of ternary fluid\nmixtures using the lattice Boltzmann method, both when all the surface tensions\nare equal and when they have different values. Previous theoretical works\ntypically rely on analysing the sign of the eigenvalues resulting from a simple\nlinear stability analysis, but we find this does not explain the fluid\nmorphologies observed. Here, by combining systematic computer simulations over\nthe full range of the composition space and theoretical analysis on the\neigenvalues and eigenvectors of the unstable modes, we identify four\nfundamental phase separation pathways. In particular, we highlight a dominant\nbut so-far overlooked mechanism involving enrichment and instability of the\nminor component at the fluid-fluid interface",
        "positive": "Mode-coupling theory for mixtures of athermal self-propelled particles: Dense or glassy active matter, as a result of its remarkable resemblance to\npassive glass-forming materials, is enjoying increasing scientific interest. To\nbetter grasp the subtle effect of active motion on the process of\nvitrification, a number of active mode-coupling theories (MCTs) have recently\nbeen developed. These have proven capable of qualitatively predicting important\nparts of the active glassy phenomenology. However, most efforts so far have\nonly considered single-component materials, and their derivations are arguably\nmore complex than the standard MCT case, which might hinder broader usage. Here\nwe present a detailed derivation of a distinct active MCT for mixtures of\nathermal self-propelled particles that is more transparent than previously\nintroduced versions. The key insight is that we can follow a similar strategy\nfor our overdamped active system as is typically used for passive underdamped\nMCT. Interestingly, when only considering one particle species, our theory\ngives the exact same result as the one obtained in previous work which employed\na highly different mode-coupling strategy. Moreover, we assess the quality of\nthe theory and its novel extension to multi-component materials by using it to\npredict the dynamics of a Kob-Andersen mixture of athermal active Brownian\nquasi-hard spheres. We demonstrate that our theory is able to capture all\nqualitative features, most notably the location of the optimum of the dynamics\nwhen the persistence length and cage length coincide, for each combination of\nparticle types."
    },
    {
        "anchor": "Ion correlation driven like-charge attraction in multivalent salt\n  solutions: The electrostatic double layer force is key to determining the stability and\nself-assembly of charged colloids and many other soft matter systems. Fully\nunderstanding the attractive force between two like-charged surfaces remains a\ngreat challenge. Here we apply the modified Gaussian renormalized fluctuation\ntheory to study ion correlation-driven like-charge attraction in multivalent\nsalt solutions. The effects of spatially varying ion correlations on the\nstructure of overlapping double layers and their free energy are\nself-consistently accounted for. In the presence of multivalent salts,\nincreasing surface charge or counterion valency leads to a short-range\nattraction. We demonstrate that although both overcharging and like-charge\nattraction are outcomes of ion correlation, there is no causal relationship\nbetween them. Our theory also captures the non-monotonic dependence of\nlike-charge attraction on multivalent salt concentration. The reduction of\nattraction at high salt concentrations could be a contributing factor towards\nthe reentrant stability of charged colloidal suspensions. Our theoretical\npredictions are consistent with the observations reported in experiments and\nsimulations.",
        "positive": "Considerations on the relaxation time in shear-driven jamming: We study the jamming transition in a model of elastic particles under shear\nat zero temperature, with a focus on the relaxation time $\\tau_1$. This\nrelaxation time is from two-step simulations where the first step is the\nordinary shearing simulation and the second step is the relaxation of the\nenergy after stopping the shearing. $\\tau_1$ is determined from the final\nexponential decay of the energy. Such relaxations are done with many different\nstarting configuration generated by a long shearing simulation in which the\nshear varible $\\gamma$ slowly increases. We study the correlations of both\n$\\tau_1$, determined from the decay, and the pressure, $p_1$, from the starting\nconfigurations as a function of the difference in $\\gamma$. We find that the\ncorrelations of $p_1$ are more long lived than the ones of $\\tau_1$ and find\nthat the reason for this is that the individual $\\tau_1$ is controlled both by\n$p_1$ of the starting configuration and a random contribution which depends on\nthe relaxation path length -- the average distance moved by the particles\nduring the relaxation. We further conclude that it is $\\gammatau$, determined\nfrom the correlations of $\\tau_1$, which is the relevant one when the aim is to\ngenerate data that may be used for determining the critical exponent that\ncharacterizes the jamming transition."
    },
    {
        "anchor": "Shear-induced reaction-limited aggregation kinetics of Brownian\n  particles at arbitrary concentrations: The aggregation of interacting Brownian particles in sheared concentrated\nsuspensions is an important issue in colloid and soft matter science per se.\nAlso, it serves as a model to understand biochemical reactions occurring in\nvivo where both crowding and shear play an important role. We present an\neffective medium approach within the Smoluchowski equation with shear which\nallows one to calculate the encounter kinetics through a potential barrier\nunder shear at arbitrary colloid concentrations. Experiments on a model\ncolloidal system in simple shear flow support the validity of the model in the\nrange considered. By generalizing Kramers' rate theory to the presence of\ncollective hydrodynamics, our model explains the significant increase in the\nshear-induced reaction-limited aggregation kinetics upon increasing the colloid\nconcentration.",
        "positive": "Stratification of polymer mixtures in drying droplets: hydrodynamics and\n  diffusion: We study the evaporation-induced stratification of a mixture of short and\nlong polymer chains in a drying droplet using molecular simulations. We\nsystematically investigate the effects of hydrodynamic interactions (HI) on\nthis process by comparing hybrid simulations accounting for HI between polymers\nthrough the multiparticle collision dynamics technique with free-draining\nLangevin dynamics simulations neglecting the same. We find that the dried\nsupraparticle morphologies are homogeneous when HI are included but are\nstratified in core--shell structures (with the short polymers forming the\nshell) when HI are neglected. The simulation methodology unambiguously\nattributes this difference to the treatment of the solvent in the two models.\nWe rationalize the presence (or absence) of stratification by measuring\nphenomenological multicomponent diffusion coefficients for the polymer\nmixtures. The diffusion coefficients show the importance of not only solvent\nbackflow but also HI between polymers in controlling the dried supraparticle\nmorphology."
    },
    {
        "anchor": "Snaking of a fluid in two dimensions: The nature of physical processes can depend substantially on the\ndimensionality of a system. One such example are buckling instabilities, which\narise from the competition between axial compression and bending in elastic\nfilaments. Thus, coiling of a jet of viscous fluid falling on a substrate\n(honey poured on a toast) \\cite{maha1,griffiths} behaves quite differently from\nthe coiling of viscous sheets (volcanous lava sliding on a crust)\n\\cite{johnson,ramberg}. Here we consider a novel effect of coiling of a fluid\njet confined to a two dimensional film.",
        "positive": "The interplay of sedimentation and crystallization in hard-sphere\n  suspensions: We study crystal nucleation under the influence of sedimentation in a model\nof colloidal hard spheres via Brownian Dynamics simulations. We introduce two\nexternal fields acting on the colloidal fluid: a uniform gravitational field\n(body force), and a surface field imposed by pinning a layer of equilibrium\nparticles (rough wall). We show that crystal nucleation is suppressed in\nproximity of the wall due to the slowing down of the dynamics, and that the\nspatial range of this effect is governed by the static length scale of bond\norientational order. For distances from the wall larger than this length scale,\nthe nucleation rate is greatly enhanced by the process of sedimentation, since\nit leads to a higher volume fraction, or a higher degree of supercooling, near\nthe bottom. The nucleation stage is similar to the homogeneous case, with\nnuclei being on average spherical and having crystalline planes randomly\noriented in space. The growth stage is instead greatly affected by the symmetry\nbreaking introduced by the gravitation field, with a slowing down of the\nattachment rate due to density gradients, which in turn cause nuclei to grow\nfaster laterally. Our findings suggest that the increase of crystal nucleation\nin higher density regions might be the cause of the large discrepancy in the\ncrystal nucleation rate of hard spheres between experiments and simulations, on\nnoting that the gravitational effects in previous experiments are not\nnegligible."
    },
    {
        "anchor": "Spiral wave drift in an electric field and scroll wave instabilities: I present the numerical computation of speed and direction of the drift of a\nspiral wave in an excitable medium in the presence of an electric field. In\ncontrast to earlier results, the drift speed presents a strong variation close\nto the parameter value where the drift speed component along the field changes\ndirection. Using a simple phenomenological model and results from a numerical\nlinear stability analysis of scroll waves, I show this behavior can be\nattributed to a resonance of the meander modes with the translation modes of\nthe spiral wave. Extending this phenomenological model to scroll waves also\nclarifies the link between the drift and long wavelength instabilities of\nscroll waves.",
        "positive": "Extreme bendability of DNA double helix due to bending asymmetry: Experimental data of the DNA cyclization (J-factor) at short length scales,\nas a way to study the elastic behavior of tightly bent DNA, exceed the\ntheoretical expectation based on the wormlike chain (WLC) model by several\norders of magnitude. Here, we propose that asymmetric bending rigidity of the\ndouble helix in the groove direction can be responsible for extreme bendability\nof DNA at short length scales and it also facilitates DNA loop formation at\nthese lengths. To account for the bending asymmetry, we consider the asymmetric\nelastic rod (AER) model which has been introduced and parametrized in an\nearlier study (B. Eslami-Mossallam and M. Ejtehadi, Phys. Rev. E 80, 011919\n(2009)). Exploiting a coarse grained representation of DNA molecule at base\npair (bp) level, and using the Monte Carlo simulation method in combination\nwith the umbrella sampling technique, we calculate the loop formation\nprobability of DNA in the AER model. We show that, for DNA molecule has a\nlarger J-factor compared to the WLC model which is in excellent agreement with\nrecent experimental data."
    },
    {
        "anchor": "Inferring the effective thickness of polyelectrolytes from stretching\n  measurements at various ionic strengths: applications to DNA and RNA: By resorting to the thick-chain model we discuss how the stretching response\nof a polymer is influenced by the self-avoidance entailed by its finite\nthickness. The characterization of the force versus extension curve for a thick\nchain is carried out through extensive stochastic simulations. The\ncomputational results are captured by an analytic expression that is used to\nfit experimental stretching measurements carried out on DNA and single-stranded\nRNA (poly-U) in various solutions. This strategy allows us to infer the\napparent diameter of two biologically-relevant polyelectrolytes, namely DNA and\npoly-U, for different ionic strengths. Due to the very different degree of\nflexibility of the two molecules, the results provide insight into how the\napparent diameter is influenced by the interplay between the\n(solution-dependent) Debye screening length and the polymers' ``bare''\nthickness. For DNA, the electrostatic contribution to the effective radius,\n$\\Delta$, is found to be about 5 times larger than the Debye screening length,\nconsistently with previous theoretical predictions for highly-charged stiff\nrods. For the more flexible poly-U chains the electrostatic contribution to\n$\\Delta$ is found to be significantly smaller than the Debye screening length.",
        "positive": "Quantum Chaos of Bogoliubov Waves for a Bose-Einstein Condensate in\n  Stadium Billiards: We investigate the possibility of quantum (or wave) chaos for the Bogoliubov\nexcitations of a Bose-Einstein condensate in billiards. Because of the mean\nfield interaction in the condensate, the Bogoliubov excitations are very\ndifferent from the single particle excitations in a non-interacting system.\nNevertheless, we predict that the statistical distribution of level spacings is\nunchanged by mapping the non-Hermitian Bogoliubov operator to a real symmetric\nmatrix. We numerically test our prediction by using a phase shift method for\ncalculating the excitation energies."
    },
    {
        "anchor": "Universal solvent quality crossover of the zero shear rate viscosity of\n  semidilute DNA solutions: The scaling behaviour of the zero shear rate viscosity of semidilute\nunentangled DNA solutions, in the double crossover regime driven by temperature\nand concentration, is mapped out by systematic experiments. The viscosity is\nshown to have a power law dependence on the scaled concentration $c/c^*$, with\nan effective exponent that depends on the solvent quality parameter $z$. The\ndetermination of the form of this universal crossover scaling function requires\nthe estimation of the $\\theta$ temperature of dilute DNA solutions in the\npresence of excess salt, and the determination of the solvent quality parameter\nat any given molecular weight and temperature. The $\\theta$ temperature is\ndetermined to be $T_\\theta \\approx 15^\\circ$ C using static light scattering,\nand the solvent quality parameter has been determined by dynamic light\nscattering.",
        "positive": "Equilibrium and kinetics at the coil-to-globule transition of star and\n  comb heteropolymers in infinitely dilute solutions: By means of continuous space Monte Carlo simulation we study conformational\nstructures formed by star and comb heteropolymers during kinetics of folding\nfrom the coil to the globule, as well as the corresponding equilibrium states\non going from the good to the poor solution. Particular examples of combs with\nhydrophobic backbone and hydrophilic side-groups (and vice versa), as well as\nstars with flexible and semi-stiff arms are studied. It is interesting to note\nthat star-like conformations naturally appear for a comb polymer with a\nstrongly hydrophobic backbone. We emphasise the crucial difference in the\nspatial distribution of hydrophobic and hydrophilic monomers within the\nglobular states for the above mentioned two types of combs. In case of stars,\nthe non-equilibrium states during kinetics of the coil-to-globule transition\ncorrespond to formation of localised pearls within flexible arms, whereas\nsemi-stiff arms prefer to join with each other remaining essentially extended.\nThese studies present natural extension of our previous works on the\nequilibrium and kinetic properties of linear and ring heteropolymers based on\nthe Gaussian self-consistent method and lattice Monte Carlo technique. However,\nin studying polymers with more nontrivial topology continuous space simulation\nhas some essential advantages."
    },
    {
        "anchor": "Topography and instability of monolayers near domain boundaries: We theoretically study the topography of a biphasic surfactant monolayer in\nthe vicinity of domain boundaries. The differing elastic properties of the two\nphases generally lead to a nonflat topography of ``mesas'', where domains of\none phase are elevated with respect to the other phase. The mesas are steep but\nlow, having heights of up to 10 nm. As the monolayer is laterally compressed,\nthe mesas develop overhangs and eventually become unstable at a surface tension\nof about K(dc)^2 (dc being the difference in spontaneous curvature and K a\nbending modulus). In addition, the boundary is found to undergo a\ntopography-induced rippling instability upon compression, if its line tension\nis smaller than about K(dc). The effect of diffuse boundaries on these features\nand the topographic behavior near a critical point are also examined. We\ndiscuss the relevance of our findings to several experimental observations\nrelated to surfactant monolayers: (i) small topographic features recently found\nnear domain boundaries; (ii) folding behavior observed in mixed phospholipid\nmonolayers and model lung surfactants; (iii) roughening of domain boundaries\nseen under lateral compression; (iv) the absence of biphasic structures in\ntensionless surfactant films.",
        "positive": "The interaction between colloids in polar mixtures above Tc: We calculate the interaction potential between two colloids immersed in an\naqueous mixture containing salt near or above the critical temperature. We find\nan attractive interaction far from the coexistence curve due to the combination\nof preferential solvent adsorption at the colloids' surface and preferential\nion solvation. We show that the ion-specific interaction strongly depends on\nthe amount of salt added as well as on the mixture composition. Our results are\nin accord with recent experiments. For a highly antagonistic salt of\nhydrophilic anions and hydrophobic cations, a repulsive interaction at an\nintermediate inter-colloid distance is predicted even though both the\nelectrostatic and adsorption forces alone are attractive."
    },
    {
        "anchor": "Wrinkling of freely floating smectic films: We demonstrate spontaneous wrinkling as a transient dynamical pattern in thin\nfreely floating smectic liquid-crystalline films. The peculiarity of such films\nis that, while flowing liquid-like in the film plane, they cannot quickly\nexpand in the direction perpendicular to that plane. At short time scales they\ntherefore behave in two dimensions like quasi-incompressible membranes. Such\nfilms can develop a transient undulation instability or form bulges in response\nto lateral compression. Optical experiments with freely floating bubbles on\nparabolic flights and in ground lab experiments are reported. The\ncharacteristic wavelengths of the wrinkles are in the submillimeter range. We\ndemonstrate the dynamic nature of the pattern formation mechanism and develop a\nbasic model for the wavelength selection and wrinkle orientation.",
        "positive": "Modelling of strain fields in sheared colloidal glasses using Eshelby\n  inclusions: When amorphous solids are strained they display elastic deformation at small\nstrain, however, beyond a critical strain they yield and begin to flow\nplastically. The origin of this plasticity lies in the irreversible\nrearrangement of particles. Such rearrangements have been shown to give rise to\na long-ranged quadrupolar strain field, similar to Eshebly's spherical\ninclusions. However, their spatio-temporal organisation at finite temperatures\nand finite shear rate remains unclear. Here, we have investigated the strain\nfield in sheared colloidal glasses. We show that the strain field in\nhomogeneous flows can be modelled using a distribution of Eshelby inclusions.\nIn particular, we show that the non-trivial decay of spatial strain\ncorrelations in sheared colloidal glasses is a result of elastic interactions\nbetween plastic rearrangements that form at spatially correlated locations."
    },
    {
        "anchor": "Non-equilibrium surface growth in a hybrid inorganic-organic system: Using kinetic Monte Carlo simulations, we show that molecular morphologies\nfound in non-equilibrium growth can be strongly different from those at\nequilibrium. We study the prototypical hybrid inorganic-organic system 6P on\nZnO(10-10) during thin film adsorption, and find a wealth of phenomena\nincluding re-entrant growth, a critical adsorption rate and observables that\nare non-monotonous with the adsorption rate. We identify the transition from\nlying to standing molecules with a critical cluster size and discuss the\ncompetition of time scales during growth in terms of a rate equation approach.\nOur results form a basis for understanding and predicting collective\norientational ordering during growth in hybrid material systems.",
        "positive": "Relaxation functions and dynamical heterogeneities in a model of\n  chemical gel interfering with glass transition: We investigate the heterogeneous dynamics in a model, where chemical gelation\nand glass transition interplay, focusing on the dynamical susceptibility. Two\nindependent mechanisms give raise to the correlations, which are manifested in\nthe dynamical susceptibility: one is related to the presence of permanent\nclusters, while the other is due to the increase of particle crowding as the\nglass transition is approached. The superposition of these two mechanisms\noriginates a variety of different behaviours. We show that these two mechanisms\ncan be unentangled considering the wave vector dependence of the dynamical\nsusceptibility."
    },
    {
        "anchor": "Calorimetric evidence for the existence of an intermediate phase between\n  the ferroelectric nematic phase and the nematic phase in the liquid crystal\n  RM734: The idea that rod-like molecules possessing an electric dipole moment could\nexhibit a ferroelectric nematic phase was suggested more than a century ago.\nHowever, only recently such a phase has been reported for two quite different\nliquid crystals: RM734 (4-[(4-nitrophenoxy)carbonyl)]phenyl\n2,4-dimethoxybenzoate) and DIO (2.3',4',5'-tetrafluoro[1,1'-biphenyl]-4-yl\n2.6-difluoro-4-(5-propyl-1,3-dioxan-2-yl) benzoate). For RM734 a direct\nferroelectric nematic (NF) to classical nematic N transition was reported,\nwhereas for DIO an intermediate phase Nx was discovered between the NF and the\nN phases. Here we present high-resolution calorimetric evidence that an\nintermediate Nx phase also exists in RM734 along a narrow temperature range\nbetween the NF and the N phases.",
        "positive": "Unveiling the influence of device stiffness in single macromolecule\n  unfolding: Single-molecule stretching experiments on DNA, RNA, and other biological\nmacromolecules opened up the possibility of an impressive progress in many\nfields of Life and Medical sciences. The reliability of such experiments may be\ncrucially limited by the possibility of determining the influence of the\napparatus on the experimental outputs. Here we deduce an analytical model that\nwe show to be coherent with previous numerical results and that quantitively\nreproduce AFM experimental tests on titin macromolecules and P-selectin AFM\nexperiments with variable probe stiffnesses. We believe that the obtained\nanalytical description can represent an important step forward in the\ninterpretation of Single Molecule Force Spectroscopy experiments and\nintermolecular interactions phenomena."
    },
    {
        "anchor": "Dynamics of noncohesive confined granular media: Despite the ubiquitousness and technological and scientific importance of\ngranular matter, our understanding is still very poor compared to molecular\nfluids and solids. Until today, there is no unified description, which indeed\nseems unreachable. However, it has been proposed that important advances could\nbe attained for noncohesive, hard-sphere like systems, by combining fluid\ndynamics with phase-field modeling through an appropriate order parameter\n(Aranson and Tsimring, 2006). Here, we present a review of the dynamics of\nconfined granular matter, for which this systematic approach has proven its\nvalue. Motivated by the pioneering work of Olafsen and Urbach (1998), many\nexperimental, theoretical and numerical studies of model confined granular\nsystems have been realized, which have unveiled a very large variety of\nfundamental phenomena. In this review, we focus on few of these fundamental\naspects, namely phase coexistence, effective surface tension, and a detailed\ndescription of the liquid state.",
        "positive": "Simultaneous Phase Separation and Pattern Formation in Chiral Active\n  Mixtures: Chiral active particles, or self-propelled circle swimmers, from sperm cells\nto asymmetric Janus colloids, form a rich set of patterns, which are different\nfrom those seen in linear swimmers. Such patterns have mainly been explored for\nidentical circle swimmers, while real-world circle swimmers, typically possess\na frequency distribution. Here we show that even the simplest mixture of\n(velocity-aligning) circle swimmers with two different frequencies, hosts a\ncomplex world of superstructures: The most remarkable example comprises a\nmicroflock pattern, formed in one species, while the other species phase\nseparates and forms a macrocluster, coexisting with a gas phase. Here, one\nspecies microphase-separates and selects a characteristic length scale, whereas\nthe other one macrophase separates and selects a density. A second notable\nexample, here occurring in an isotropic system, are patterns comprising two\ndifferent characteristic length scales, which are controllable via frequency\nand swimming speed of the individual particles."
    },
    {
        "anchor": "Formation of a strong negative wake behind a helical swimmer in a\n  viscoelastic fluid: We investigate the effects of helical swimmer shape (i.e., helical pitch\nangle and tail thickness) on swimming dynamics in a constant viscosity\nviscoelastic (Boger) fluid via a combination of particle tracking velocimetry,\nparticle image velocimetry and 3D simulations of the FENE-P model. The 3D\nprinted helical swimmer is actuated in a magnetic field using a custom-built\nrotating Helmholtz coil. Our results indicate that increasing the swimmer tail\nthickness and pitch angle enhances the normalized swimming speed (i.e., ratio\nof swimming speed in the Boger fluid to that of the Newtonian fluid).\nStrikingly, unlike the Newtonian fluid, the viscoelastic flow around the\nswimmer is characterized by formation of a front-back flow asymmetry that is\ncharacterized by a strong negative wake downstream of the swimmer. Evidently,\nthe strength of the negative wake is inversely proportional to the normalized\nswimming speed. Three-dimensional simulations of the swimmer with FENE-P model\nwith conditions that match those of experiments, confirm formation of a similar\nfront-back flow asymmetry around the swimmer. Finally, by developing an\napproximate force balance in the streamwise direction, we show that the\ncontribution of polymer stresses in the interior region of the helix may\nprovide a mechanism for swimming enhancement or diminution in the viscoelastic\nfluid.",
        "positive": "Generalized Lorentz reciprocal theorem in complex fluids and in\n  non-isothermal systems: The classical Lorentz reciprocal theorem (LRT) was originally derived for\nslow viscous flows of incompressible Newtonian fluids under the isothermal\ncondition. In the present work, we extend the LRT from simple to complex fluids\nwith open or moving boundaries that maintain non-equilibrium stationary states.\nIn complex fluids, the hydrodynamic flow is coupled with the evolution of\ninternal degrees of freedom such as the solute concentration in two-phase\nbinary fluids and the spin in micropolar fluids. The dynamics of complex fluids\ncan be described by local conservation laws supplemented with local\nconstitutive equations satisfying Onsager's reciprocal relations (ORR). We\nconsider systems in quasi-stationary states close to equilibrium, controlled by\nthe boundary variables whose evolution is much slower than the relaxation in\nthe system. For these quasi-stationary states, we derive the generalized\nLorentz reciprocal theorem (GLRT) and global Onsager's reciprocal relations\n(GORR) for the slow variables at boundaries. This establishes the connection\nbetween ORR for local constitutive equations and GORR for constitutive\nequations at boundaries. Finally, we show that the LRT can be further extended\nto non-isothermal systems by considering as an example the thermal conduction\nin solids and still fluids."
    },
    {
        "anchor": "Anomalous fluxes in overdamped Brownian dynamics with Lorentz force: We study the stochastic motion of a particle subject to spatially varying\nLorentz force in the small-mass limit. The limiting procedure yields an\nadditional drift term in the overdamped equation that cannot be obtained by\nsimply setting mass to zero in the velocity Langevin equation. We show that\nwhereas the overdamped equation of motion accurately captures the position\nstatistics of the particle, it leads to unphysical fluxes in the system that\npersist in the long time limit; an anomalous result inconsistent with thermal\nequilibrium. These fluxes are calculated analytically from the overdamped\nequation of motion and found to be in quantitative agreement with Brownian\ndynamics simulations. Our study suggests that the overdamped approximation,\nthough perfectly suited for position statistics, can yield unphysical values\nfor velocity-dependent variables such as flux and entropy production.",
        "positive": "Correlation functions in ionic liquid at coexistence with ionic crystal.\n  Results of the Brazovskii-type field theory: Correlation functions in the restricted primitive model are calculated within\na field-theoretic approach in the one-loop self-consistent Hartree\napproximation. The correlation functions exhibit damped oscillatory behavior as\nfound before in the Gaussian approximation [Ciach at. al., J. Chem. Phys. {\\bf\n118}, 3702 (2003)]. The fluctuation contribution leads to a renormalization of\nboth the amplitude and the decay length of the correlation functions. The\nrenormalized quantities show qualitatively different behavior than their\nmean-field (MF) counterparts. While the amplitude and the decay length both\ndiverge in MF when the $\\lambda$-line is approached, the renormalized\nquantities remain of order of unity in the same dimensionless units down to the\ncoexistence with the ionic crystal. Along the line of the phase transition the\ndecay length and the period of oscillations are independent of density, and\ntheir values in units of the diameter of the ions are $\\alpha_0^{-1}\\approx 1$\nand $2\\pi/\\alpha_1\\approx 2.8$ respectively."
    },
    {
        "anchor": "Highly localized clustering states in a granular gas driven by a\n  vibrating wall: An ensemble of inelastically colliding grains driven by a vibrating wall in\n2D exhibits density clustering. Working in the limit of nearly elastic\ncollisions and employing granular hydrodynamics, we predict, by a marginal\nstability analysis, a spontaneous symmetry breaking of the extended clustering\nstate (ECS). 2D steady-state solutions found numerically describe localized\nclustering state (LCSs). Time-dependent granular hydrodynamic simulations show\nthat LCSs can develop from natural initial conditions. The predicted\ninstability should be observable in experiment.",
        "positive": "Shape-Driven Caging Dynamics of Hard Polygons: The fundamentals of Brownian motion have been largely well understood since\nthe early 20th century, with most recent additions focusing on understanding\nanomalous diffusion via rescaling of drag coefficents. That focus emphasizes\nlong-time dynamic behavior, but recent results indicate that additional,\nsecondary modes are also present at short and intermediate times in fluids of\nanisotropic particles. Here, we study the dynamics of a representative family\nof nearly-hard n-gons. Using molecular dynamics simulations, we study a\ndistinct form of caging only present in anisotropic systems. We show that this\ncaging behavior emerges in the mean squared displacement of n-gons at\nintermediate particle volume fractions. We then develop an extended Langevin\ntheory directly coupling translational and rotational motion as a function of\nthe relative anisotropy for different n-gons that predicts the observed caging\nbehavior. Extending our theory to incorporate secondary, off-phase\ncross-correlations between particles further enables the prediction of both\ntranslational and rotational relaxation times of the system."
    },
    {
        "anchor": "Polyelectrolyte and polyampholyte effects in synthetic and biological\n  macromolecules: The nature of electrostatic interactions involving polyanions modulate the\nproperties of both synthetic and biological macromolecules. Although intensely\nstudied for decades the interplay of many length scales has prevented a\ncomplete resolution of some of the basic questions such as how the\nelectrostatic persistence length ($l_e$) varies with ionic strength ($I$). In\nthis review we describe certain characteristics of polyelectrolytes (PAs) and\npolyampholytes (PAs), which are polymers whose monomers have a random\ndistribution of opposite charges. After reviewing the current theoretical\nunderstanding of the dependence of $l_e$ on $I$ we present experimental data\nthat conform to two distinct behavior. For RNA and DNA it is found that that\n$l_e \\sim I^{-1}$ whereas for some proteins and other polyelectrolytes $l_e\n\\sim i^{-1/2}$. A scaling type theory, which delineates charge correlation and\npure polyelectrolyte effects for the shape of PAs that is valid over a wide\nrange of salt concentration is described. We also use theory and simulations to\nargue that the distinct stages in the kinetics of collapse of PAs (with a net\ncharge that is small enough to induce globule formation) and PEs (relevant for\nRNA folding) are similar. In both cases the major initial conformation change\ninvolves formation of metastable pearl-necklace structures. In the coarsening\nprocess large clusters (pearls) grow at the expense of smaller ones by a\nprocess that is reminiscent of Lifshitz-Slyozov mechanism. Finally, recent\ntheories and single molecule experiments on stretching of single stranded DNA\nand PEs further sheds insights into the complex behavior of charged\nmacromolecules. The survey, which is limited to very few topics, shows the\nimportance of polyelectrolyte effects in a wide range of disciplines.",
        "positive": "Slow dynamics, aging, and glassy rheology in soft and living matter: We explore the origins of slow dynamics, aging and glassy rheology in soft\nand living matter. Non-diffusive slow dynamics and aging in materials\ncharacterised by crowding of the constituents can be explained in terms of\nstructural rearrangement or remodelling events that occur within the jammed\nstate. In this context, we introduce the jamming phase diagram proposed by Liu\nand Nagel to understand the ergodic-nonergodic transition in these systems, and\ndiscuss recent theoretical attempts to explain the unusual,\nfaster-than-exponential dynamical structure factors observed in jammed soft\nmaterials. We next focus on the anomalous rheology (flow and deformation\nbehaviour) ubiquitous in soft matter characterised by metastability and\nstructural disorder, and refer to the Soft Glassy Rheology (SGR) model that\nquantifies the mechanical response of these systems and predicts aging under\nsuitable conditions. As part of a survey of experimental work related to these\nissues, we present x-ray photon correlation spectroscopy (XPCS) results of the\naging of laponite clay suspensions following rejuvenation. We conclude by\nexploring the scientific literature for recent theoretical advances in the\nunderstanding of these models and for experimental investigations aimed at\ntesting their predictions."
    },
    {
        "anchor": "Electric field induced birefringence in non-aqueous dispersions of\n  mineral nanorods: Lanthanum phosphate (LaPO4) nanorods dispersed in the non-aqueous solvent of\nethylene glycol form a system exhibiting large intrinsic birefringence, high\ncolloidal stability and the ability to self-organize into liquid crystalline\nphases. In order to probe the electro-optical response of these rod dispersions\nwe study here the electric-field-induced birefringence, also called Kerr\neffect, for a concentrated isotropic liquid state with an in-plane a.c.\nsinusoidal electric field, in conditions of directly applied (electrodes in\ncontact with the sample) or externally applied (electrodes outside the sample\ncell) fields. Performing an analysis of the electric polarizability of our\nrod-like particles in the framework of Maxwell-Wagner-OKonski theory, we\naccount quantitatively for the coupling between the induced steady-state\nbirefringence and the electric field as a function of the voltage frequency for\nboth sample geometries. The switching time of this non-aqueous transparent\nsystem has been measured, and combined with its high Kerr coefficients and its\nfeatures of optically isotropic offstate and athermal phase behavior, this\nrepresents a promising proof-of-concept for the integration of anisotropic\nnanoparticle suspensions into a new generation of electro-optical devices.",
        "positive": "Trajectories of a droplet driven by an internal active device: We consider a liquid droplet which is propelled solely by internal flow. In a\nsimple model, this flow is generated by an autonomous actuator, which moves on\na prescribed trajectory inside the droplet. In a biological system, the device\ncould represent a motor, carrying cargo and moving on a filamentary track. We\nwork out the general framework to compute the self-propulsion of the droplet as\na function of the actuating forces and the trajectory. The simplest autonomous\ndevice is composed of three point forces. Such a device gives rise to linear,\ncircular or spiraling motion of the droplet, depending on whether the device is\nstationary or moving along a radial track. As an example of a more complex\ntrack we study in detail a spherical looped helix, inspired by recent studies\non the propulsion of Synechococcus1 and Myxobacteria2. The droplet trajectories\nare found to depend strongly on the orientation of the device and the direction\nof the forces relative to the track with the posibility of unbounded motion\neven for time independent forcing."
    },
    {
        "anchor": "Segregation by membrane rigidity in flowing binary suspensions of\n  elastic capsules: Spatial segregation in the wall normal direction is investigated in\nsuspensions containing a binary mixture of Neo-Hookean capsules subjected to\npressure driven flow in a planar slit. The two components of the binary mixture\nhave unequal membrane rigidities. The problem is studied numerically using an\naccelerated implementation of the boundary integral method. The effect of a\nvariety of parameters was investigated, including the capillary number,\nrigidity ratio between the two species, volume fraction, confinement ratio, and\nthe number fraction of the more floppy particle $X_f$ in the mixture. It was\nobserved that in suspensions of pure species, the mean wall normal positions of\nthe stiff and the floppy particles are comparable. In mixtures, however, the\nstiff particles were found to be increasingly displaced towards the walls with\nincreasing $X_f$, while the floppy particles were found to increasingly\naccumulate near the centerline with decreasing $X_f$. The origins of this\nsegregation is traced to the effect of the number fraction $X_f$ on the\nlocalization of the stiff and the floppy particles in the near wall region --\nthe probability of escape of a stiff particle from the near wall region to the\ninterior is greatly reduced with increasing $X_f$, while the exact opposite\ntrend is observed for a floppy particle with decreasing $X_f$. Simple model\nstudies on heterogeneous pair collisions involving a stiff and a floppy\nparticle mechanistically explain this observation. The key result in these\nstudies is that the stiff particle experiences much larger cross-stream\ndisplacement in heterogeneous collisions than the floppy particle. A unified\nmechanism incorporating the wall-induced migration of deformable particles and\nthe particle fluxes associated with heterogeneous and homogeneous pair\ncollisions is presented.",
        "positive": "Ordered clusters and dynamical states of particles in a vibrated fluid: Fluid-mediated interactions between particles in a vibrating fluid lead to\nboth long range attraction and short range repulsion. The resulting patterns\ninclude hexagonally ordered micro-crystallites, time-periodic structures, and\nchaotic fluctuating patterns with complex dynamics. A model based on streaming\nflow gives a good quantitative account of the attractive part of the\ninteraction."
    },
    {
        "anchor": "Equilibrium and non-equilibrium molecular dynamics approaches for the\n  linear viscoelasticity of polymer melts: Viscoelastic properties of polymer melts are particularly challenging to\ncompute due to the intrinsic stress fluctuations in molecular dynamics (MD). We\ncompared equilibrium and non-equilibrium MD approaches for extracting the\nstorage (G') and loss moduli (G\") over a wide frequency range from a\nbead-spring chain model, in both unentangled and entangled regimes. We found\nthat, with properly chosen data processing and noise reduction procedures,\ndifferent methods render quantitatively equivalent results. In equilibrium MD\n(EMD), applying the Green-Kubo relation with a multi-tau correlator method for\nnoise filtering generates smooth stress relaxation modulus profiles, from which\naccurate G' and G\" can be obtained. For unentangled chains, combining the Rouse\nmodel with a short-time correction provides a convenient option that\ncircumvents the stress fluctuation challenge altogether. For non-equilibrium MD\n(NEMD), we found that combining a stress pre-averaging treatment with discrete\nFourier transform analysis reliably computes G' and G\" with much shorter\nsimulation length than previously reported. Comparing the efficiency and\nstatistical accuracy of these methods, we concluded that EMD is both reliable\nand efficient, and is suitable when the whole spectrum of linear viscoelastic\nproperties is desired, whereas NEMD offers flexibility when only some frequency\nranges are of interest.",
        "positive": "Note: Equation of state and the freezing point in the hard-sphere model: The merits of different analytical equations of state for the hard-sphere\nsystem with respect to the recently computed high-accuracy value of the\nfreezing-point packing fraction are assessed. It is found that the\nCarnahan-Starling-Kolafa and the branch-point approximant equations of state\nyield the best performance."
    },
    {
        "anchor": "Comment on Bilayer aggregate microstructure determines viscoelasticity\n  of lung surfactant suspensions by C.O. Ciutara and J.A. Zasadzinski, Soft\n  Matter, 2021, 17, 5170-5182: For applications of pulmonary surfactant delivery to the lungs, the question\nof rheology of the existing clinical formulations is of upmost importance.\nRecently, Ciutara and Zasadsinky (Soft Matter, 2021, 17, 5170-5182) measured\nthe rheological properties of Infasurf, Survanta and Curosurf, three of the\nmost used pulmonary surfactant substitutes. This study revealed that these\nfluids are shear-thinning and characterized by a yield stress. The results\nobtained by Ciutara et al. on Curosurf differ from our results published in\nColloids and Surfaces B: Biointerfaces, 2019, 178, 337-345 and in ACS Nano,\n2020, 14, 466 - 475. In contrast, we found that Curosurf suspensions are\nviscous Newtonian or slightly shear-thinning fluids, with no evidence of yield\nstress. The purpose of this Comment is to discuss possible causes for the\ndiscrepancy between the two studies, and to suggest that for biological fluids\nsuch as surfactant substitutes, the microrheology technique of rotational\nmagnetic spectroscopy (MRS) can provide valuable results.",
        "positive": "Dynamic Regimes for Driven Colloidal Particles on a Periodic Substrate\n  at Commensurate and Incommensurate Fillings: We examine colloidal particles driven over a periodic muffin tin substrate\nusing numerical simulations. In the absence of a driving force this system\nexhibits a rich variety of commensurate and incommensurate static phases in\nwhich topological defects can form domain walls, ordered stripes,\nsuperlattices, and disordered patchy regimes as a function of the filling\nfraction. When an external drive is applied, these different static phases\ngenerate distinct dynamical responses. At incommensurate fillings the flow\ngenerally occurs in the form of localized pulses or solitons correlated with\nthe motion of the topological defect structures. We also find dynamic\ntransitions between different types of moving states that are associated with\nchanges in the velocity force curves, structural transitions in the topological\ndefect arrangements, and modifications of the velocity distributions and\nparticle trajectories. We find that the dynamic transitions between ordered and\ndisordered flows exhibit hysteresis, while in strongly disordered regimes there\nis no hysteresis and the velocity force curves are smooth. When stripe patterns\nare present, transport can occur along the stripe direction rather than along\nthe driving direction. Structural dynamic transitions can also occur within the\npinned regimes when the applied drive causes distortions of the interstitially\npinned particles while the particles trapped at pinning sites remain immobile."
    },
    {
        "anchor": "Ionic Coulomb Blockade in Nanopores: Understanding the dynamics of ions in nanopores is essential for applications\nranging from single-molecule detection to DNA sequencing. We show both\nanalytically and by means of molecular dynamics simulations that under specific\nconditions ion-ion interactions in nanopores lead to the phenomenon of ionic\nCoulomb blockade, namely the build-up of ions inside a nanopore with specific\ncapacitance impeding the flow of additional ions due to Coulomb repulsion. This\nis the counterpart of electronic Coulomb blockade observed in mesoscopic\nsystems. We discuss the analogies and differences with the electronic case as\nwell as experimental situations in which this phenomenon could be detected.",
        "positive": "Dynamic scaling in entangled mean-field gelation polymers: We present a simple reaction kinetics model to describe the polymer synthesis\nused by Lusignan et al. (PRE, 60, 5657, 1999) to produce randomly branched\npolymers in the vulcanization class. Numerical solution of the rate equations\ngives probabilities for different connections in the final product, which we\nuse to generate a numerical ensemble of representative molecules. All\nstructural quantities probed by Lusignan et al. are in quantitative agreement\nwith our results for the entire range of molecular weights considered. However,\nwith detailed topological information available in our calculations, our\nestimate of the `rheologically relevant' linear segment length is smaller than\nthat estimated by them. We use a numerical method based on tube model of\npolymer melts to calculate the rheological properties of such molecules.\nResults are in good agreement with experiment, except that in the case of the\nlargest molecular weight samples our estimate of the zero-shear viscosity is\nsignificantly lower than the experimental findings. Using acid concentration as\nan indicator for closeness to the gelation transition, we show that the\nhigh-molecular-weight polymers considered are at the limit of mean-field\nbehavior - which possibly is the reason for this disagreement. For a truly\nmean-field gelation class of model polymers, we numerically calculate the\nrheological properties for a range of segment lengths. Our calculations show\nthat the tube theory with dynamical dilation predicts that, very close to the\ngelation limit, contribution to viscosity for this class of polymers is\ndominated by the contribution from constraint-release Rouse motion and the\nfinal viscosity exponent approaches Rouse-like value."
    },
    {
        "anchor": "Molecular Dynamics simulations and Kelvin Probe Force microscopy to\n  study of cholesterol-induced electrostatic nanodomains in complex lipid\n  mixtures: The molecular arrangement of lipids and proteins within biomembranes and\nmonolayers gives rise to complex film morphologies as well as regions of\ndistinct electrical surface potential, topographical and electrostatic\nnanoscale domains. To probe these nanodomains in soft matter is a challenging\ntask both experimentally and theoretically. This work addresses the effects of\ncholesterol, lipid composition, lipid charge, and lipid phase on the monolayer\nstructure and the electrical surface potential distribution. Atomic Force\nMicroscopy (AFM) was used to resolve topographical nanodomains and Kelvin Probe\nForce Microscopy (KPFM) to resolve electrical surface potential of these\nnanodomains in lipid monolayers. Model monolayers composed of\ndipalmitoylphosphatidylcholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine\n(DOPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC),\n1,2-dioleoyl-sn-glycero-3-[phospho-rac-(3-lysyl(1-glycerol))] (DOPG),\nsphingomyelin, and cholesterol were studied. It is shown that cholesterol\nchanges nanoscale domain formation, affecting both topography and electrical\nsurface potential. The molecular basis for differences in electrical surface\npotential was addressed with atomistic molecular dynamics (MD). MD simulations\nqualitatively match the experimental results, with 100s of mV difference in\nelectrostatic potential between liquid-disordered bilayer (Ld, less cholesterol\nand lower chain order) and a liquid-ordered bilayer (Lo, more cholesterol and\nhigher chain order). Importantly, the difference in electrostatic properties\nbetween Lo and Ld phases suggests a new mechanism by which membrane composition\ncouples to membrane function.",
        "positive": "Shear induced alignment and dynamics of elongated granular particles: The alignment, ordering and rotation of elongated granular particles was\nstudied in shear flow. The time evolution of the orientation of a large number\nof particles was monitored in laboratory experiments by particle tracking using\noptical imaging and x-ray computed tomography. The experiments were\ncomplemented by discrete element simulations. The particles develop an\norientational order. In the steady state the time and ensemble averaged\ndirection of the main axis of the particles encloses a small angle with the\nstreamlines. This shear alignment angle is independent of the applied shear\nrate, and it decreases with increasing grain aspect ratio. At the grain level\nthe steady state is characterized by a net rotation of the particles, as\ndictated by the shear flow. The distribution of particle rotational velocities\nwas measured both in the steady state and also during the initial transients.\nThe average rotation speed of particles with their long axis perpendicular to\nthe shear alignment angle is larger, while shear aligned particles rotate\nslower. The ratio of this fast/slow rotation increases with particle aspect\nratio. During the initial transient starting from an unaligned initial\ncondition, particles having an orientation just beyond the shear alignment\nangle rotate opposite to the direction dictated by the shear flow."
    },
    {
        "anchor": "Evolution of shear-induced melting in dusty plasma: The spatiotemporal development of melting is studied experimentally in a 2D\ndusty plasma suspension. Starting with an ordered lattice, and then suddenly\napplying localized shear, a pair of counter-propagating flow regions develop. A\ntransition between two melting stages is observed before a steady state is\nreached. Melting spreads with a front that propagates at the transverse sound\nspeed. Unexpectedly, coherent longitudinal waves are excited in the flow\nregion.",
        "positive": "Mechanosensitive bonds induced complex cell motility patterns: The one-dimensional crawling movement of a cell is considered in this\ntheoretical study. Our active gel model shows that for a cell with weakly\nmechanosensitive adhesion complexes, as myosin contractility increases, a cell\nstarts to move at a constant velocity. As the mechanosensitivity of the\nadhesion complexes increases, a cell can exhibit stick-slip motion. Finally, a\ncell with highly mechanosensitive adhesion complexes exhibits periodic\nback-and-forth migration. A simplified model which assumes that the cell\ncrawling dynamics are controlled by the evolution of the myosin density dipole\nand the asymmetry of adhesion complex distribution captures the motility\nbehaviors of crawling cells qualitatively. It suggests that the complex cell\ncrawling behaviors observed in the experiments could result from the interplay\nbetween the distribution of contractile force and mechanosensitive bonds."
    },
    {
        "anchor": "Slow Steady-Shear of Plastic Bead Rafts: Experimental measurements of the response of a two dimensional system of\nplastic beads subjected to steady shear are reported. The beads float at the\nsurface of a fluid substrate and are subjected to a slow, steady-shear in a\nCouette geometry. The flow consists of irregular intervals of solid-like,\njammed behavior, followed by stress relaxations. We report on statistics that\ncharacterize the stress fluctuations as a function of several parameters\nincluding shear-rate and packing density. Over a range of densities between the\nonset of flow to the onset of buckling (overpacking) of the system, the\nprobability distribution for stress fluctuations is essentially independent of\nthe packing density, particle dispersity, and interaction potential (varied by\nchanging the substrate). Finally, we compare the observed stress fluctuations\nwith those observed in other complex fluids.",
        "positive": "Selectivity in binary fluid mixtures: static and dynamical properties: Selectivity of particles in a region of space can be achieved by applying\nexternal potentials to influence the particles in that region. We investigate\nstatic and dynamical properties of size selectivity in binary fluid mixtures of\ntwo particles sizes. We find that by applying an external potential that is\nattractive to both kinds of particles, due to crowding effects, this can lead\nto one species of particles being expelled from that region, whilst the other\nspecies is attracted into the region where the potential is applied. This\nselectivity of one species of particle over the other in a localized region of\nspace depends on the density and composition of the fluid mixture. Applying an\nexternal potential that repels both kinds of particles leads to selectivity of\nthe opposite species of particles to the selectivity with attractive\npotentials. We use equilibrium and dynamical density functional theory to\ndescribe and understand the static and dynamical properties of this striking\nphenomenon. Selectivity by some ion-channels is believed to be due to this\neffect."
    },
    {
        "anchor": "Production Of Multiple 87Rb Condensates And Atom Lasers By Rf Coupling: We have investigated the rf output coupling of a 87Rb condensate from a\nIoffe-Pritchard magnetic trap. Multiple condensates in different Zeeman states\nare produced, their population being varied by playing with the duration and\nthe amplitude of the rf pulse. Both pulsed and continuous outputs (atom laser)\nhave been observed.",
        "positive": "Active fluids at circular boundaries: Swim pressure and anomalous\n  droplet ripening: We investigate the swim pressure exerted by non-chiral and chiral active\nparticles on convex or concave circular boundaries. Active particles are\nmodeled as non-interacting and non-aligning self-propelled Brownian particles.\nThe convex and concave circular boundaries are used as models representing a\nfixed inclusion immersed in an active bath and a cavity (or container)\nenclosing the active particles, respectively. We first present a detailed\nanalysis of the role of convex versus concave boundary curvature and of the\nchirality of active particles on their spatial distribution, chirality-induced\ncurrents, and the swim pressure they exert on the bounding surfaces. The\nresults will then be used to predict the mechanical equilibria of suspended\nfluid enclosures (generically referred to as 'droplets') in a bulk with active\nparticles being present either inside the bulk fluid or within the suspended\ndroplets. We show that, while droplets containing active particles and\nsuspended in a normal bulk behave in accordance with standard capillary\nparadigms, those containing a normal fluid exhibit anomalous behaviors when\nsuspended in an active bulk. In the latter case, the excess swim pressure\nresults in non-monotonic dependence of the inside droplet pressure on the\ndroplet radius. As a result, we find a regime of anomalous capillarity for a\nsingle droplet, where the inside droplet pressure increases upon increasing the\ndroplet size. In the case of two interconnected droplets, we show that\nmechanical equilibrium can occur also when they have different sizes. We\nfurther identify a regime of anomalous ripening, where two unequal-sized\ndroplets can reach a final state of equal sizes upon interconnection, in stark\ncontrast with the standard Ostwald ripening phenomenon, implying shrinkage of\nthe smaller droplet in favor of the larger one."
    },
    {
        "anchor": "Simulation of Equilibrated States via Molecular Monte Carlo Method of\n  Systems Connected to 3 Reservoirs: Metastable structures in macromolecular and colloidal systems are\nnon-equilibrium states that often have long lifetimes and cause difficulties in\nsimulating equilibrium. In order to escape from the long-lived metastable\nstates, we propose a newly devised method, molecular Monte-Carlo simulation of\nsystems connected to 3 reservoirs: chemical potential $\\mu$, pressure $P$, and\ntemperature $T$. One of these reservoirs is adjusted for the thermodynamic\nequilibrium condition according to Gibbs-Duhem equation, so that this adjusted\n3rd reservoir does not thermodynamically affect phases and states. Additional\ndegrees of freedom, i.e. system volume $V$ and the number of particles $N$,\nreduce kinetic barriers of non-equilibrium states and facilitate quick\nequilibration. We show globally-anisotropic defect-free ordered structures,\ne.g. string-like colloidal assembly, are obtained via our method.",
        "positive": "Prediction of creep failure time using machine learning: A subcritical load on a disordered material can induce creep damage. The\ncreep rate in this case exhibits three temporal regimes viz. an initial\ndecelerating regime followed by a steady-state regime and a stage of\naccelerating creep that ultimately leads to catastrophic breakdown. Due to the\nstatistical regularities in the creep rate, the time evolution of creep rate\nhas often been used to predict residual lifetime until catastrophic breakdown.\nHowever, in disordered samples, these efforts met with limited success.\nNevertheless, it is clear that as the failure is approached, the damage become\nincreasingly spatially correlated, and the spatio-temporal patterns of acoustic\nemission, which serve as a proxy for damage accumulation activity, are likely\nto mirror such correlations. However, due to the high dimensionality of the\ndata and the complex nature of the correlations it is not straightforward to\nidentify the said correlations and thereby the precursory signals of failure.\nHere we use supervised machine learning to estimate the remaining time to\nfailure of samples of disordered materials. The machine learning algorithm uses\nas input the temporal signal provided by a mesoscale elastoplastic model for\nthe evolution of creep damage in disordered solids. Machine learning algorithms\nare well-suited for assessing the proximity to failure from the time series of\nthe acoustic emissions of sheared samples. We show that materials are\nrelatively more predictable for higher disorder while are relatively less\npredictable for larger system sizes. We find that machine learning predictions,\nin the vast majority of cases, perform substantially better than other\nprediction approaches proposed in the literature."
    },
    {
        "anchor": "Knotty knits are tangles on tori: In this paper we outline a topological framework for constructing 2-periodic\nknitted stitches and an algebra for joining stitches together to form more\ncomplicated textiles. Our topological framework can be constructed from certain\ntopological \"moves\" which correspond to \"operations\" that knitters make when\nthey create a stitch. In knitting, unlike Jacquard weaves, a set of $n$ loops\nmay be combined in topologically nontrivial ways to create $n$ stitches that\nare not pairwise associated. We define a \\emph{swatch} as a construction that\nallows for these knitable knots.",
        "positive": "Steady-state, effective-temperature dynamics in a glassy material: We present an STZ-based analysis of numerical simulations by Haxton and Liu\n(HL). The extensive HL data sharply test the basic assumptions of the STZ\ntheory, especially the central role played by the effective disorder\ntemperature as a dynamical state variable. We find that the theory survives\nthese tests, and that the HL data provide important and interesting constraints\non some of its specific ingredients. Our most surprising conclusion is that,\nwhen driven at various constant shear rates in the low-temperature glassy\nstate, the HL system exhibits a classic glass transition, including\nsuper-Arrhenius behavior, as a function of the effective temperature."
    },
    {
        "anchor": "Two-stage melting induced by dislocations and grain boundaries in\n  Monolayers of Hard Spheres: Melting in two-dimensional systems has remained controversial as theory,\nsimulations, and experiments show contrasting results. One issue that obscures\nthis discussion is whether or not theoretical predictions on strictly 2D\nsystems describe those of quasi-2D experimental systems, where out-of-plane\nfluctuations may alter the melting mechanism. Using event-driven Molecular\nDynamics simulations, we find that the peculiar two-stage melting scenario of a\ncontinuous solid-hexatic and a first-order hexatic-liquid transition as\nobserved for a truly 2D system of hard disks [Bernard and Krauth, Phys. Rev.\nLett. 107, 155704 (2011)] persists for a quasi-2D system of hard spheres with\nout-of-plane particle motions as high as half the particle diameter. By\ncalculating the renormalized Young's modulus, we show that the solid-hexatic\ntransition is of the Kosterlitz-Thouless type, and occurs via dissociation of\nbound dislocation pairs. In addition, we find a first-order hexatic-liquid\ntransition that seems to be driven by a spontaneous proliferation of grain\nboundaries.",
        "positive": "Structure and coarsening at the surface of a dry three-dimensional\n  aqueous foam: We utilize total-internal reflection to isolate the two-dimensional `surface\nfoam' formed at the planar boundary of a three-dimensional sample. The\nresulting images of surface Plateau borders are consistent with Plateau's laws\nfor a truly two-dimensional foam. Samples are allowed to coarsen into a\nself-similar scaling state where statistical distributions are independent of\ntime, except for an overall scale factor. There we find that statistical\nmeasures of side number distributions, size-topology correlations, and bubble\nshapes, are all very similar to those for two-dimensional foams. However the\nsize number distribution is slightly broader and the shapes are slightly more\nelongated. A more obvious difference is that T2 processes now include the\ncreation of surface bubbles, due to rearrangement in the bulk. And von\nNeumann's law is dramatically violated for individual bubbles. But\nnevertheless, our most striking finding is that von Neumann's law appears to\nholds on average. Namely the average rate of area change for surface bubbles\nappears to be proportional to the number of sides minus six, but with\nindividual bubbles showing a distribution of deviations from this average\nbehavior."
    },
    {
        "anchor": "Dynamical Entanglement and Cooperative Dynamics in Entangled Solutions\n  of Ring and Linear Polymers: Understanding how entanglements affect the behaviour of polymeric complex\nfluids is an open challenge in many fields. To elucidate the nature and\nconsequence of entanglements in dense polymer solutions, we propose a novel\nmethod: a \"dynamical entanglement analysis\" (DEA) to extract spatio-temporal\nentanglement structures from the pair-wise displacement correlation of\nentangled chains. By applying this method to large-scale Molecular Dynamics\nsimulations of linear and unknotted, nonconcatenated ring polymers, we find a\nstrong and unexpected cooperative dynamics: the footprint of mutual entrainment\nbetween entangled chains. We show that DEA is a powerful and sensitive probe\nthat reveals previously unnoticed, and architecture-dependent, spatio-temporal\nstructures of dynamical entanglement in polymeric solutions. We also propose a\nmean-field approximation of our analysis which provides previously\nunder-appreciated physical insights into the dynamics of generic entangled\npolymers. We envisage DEA will be useful to analyse the dynamical evolution of\nentanglements in generic polymeric systems such as blends and composites.",
        "positive": "Anomalous diffusion coefficient in disordered media from NMR relaxation: Application of fractional calculus to the description of anomalous diffusion\nand relaxation processes in complex media provided one of the most impressive\nimpulses to the development of statistical physics during the last decade. In\nparticular the so-called fractional diffusion equation enabled one to capture\nthe main features of anomalous diffusion. However the price for this\nachievement is rather high - the fractional diffusion coefficient becomes an\ninvolved function of a characteristic of the media (e.g., that of the radius of\npores in the case of the porous one). Revealing this dependence from the first\nprinciples is one of the main problems in this field of science. Another one\nstill remains that of extracting this dependence from the experiment. The\nlatter problem is tackled in the present paper. Our aim is to provide detailed\nand pedagogical deriving the relationship of the fractional diffusion\ncoefficient with experimentally observable value from nuclear magnetic\nresonance (NMR) spin-lattice relaxation data. The result obtained promotes the\nNMR relaxation method to become a powerful tool in solving the problem of\nexperimental measuring the fractional diffusion coefficient. Also the merits\nand limitations of NMR relaxation method and pulsed-field gradient (PFG) NMR\nfor the research of anomalous diffusion are compared and discussed."
    },
    {
        "anchor": "Understanding the effect of the base oil on the physical adsorption\n  process of organic additives using molecular dynamics: Organic friction modifiers (OFMs) are widely added to oil to reduce the\nboundary friction in many kinds of lubricants such as vehicle engine oils. At\nthe contact area in machine elements, the OFMs form a self-assembled organic\nmonolayer. Although the friction properties of the monolayer are widely studied\non a molecular level, the formation process is not well-known. In this study,\nthe initial adsorbing process of additive molecules in explicit base oil\nmolecules are calculated using molecular dynamics. The adsorption time depends\non the structure of the base oils. Another effect of the base oil other than\n\"chain matching\" is found.",
        "positive": "The role of the energy gap in protein folding dynamics: The dynamics of folding of proteins is studied by means of a phenomenological\nmaster equation. The energy distribution is taken as a truncated exponential\nfor the misfolded states plus a native state sitting below the continuum. The\ninfluence of the gap on the folding dynamics is studied, for various models of\nthe transition probabilities between the different states of the protein. We\nshow that for certain models, the relaxation to the native state is accelerated\nby increasing the gap, whereas for others it is slowed down ."
    },
    {
        "anchor": "Momentum-Transfer to and Elementary-Excitations of a Bose-Einstein\n  Condensate by a Time-Dependent Optical Potential: We present results of calculations on Bose-Einstein condensed $^{87}$Rb atoms\nsubjected to a moving standing-wave light-potential of the form $V_L(z,t) =\nV_0(t) \\cos(q z-\\omega t)$. We calculate the mean-field dynamics (the order\nparamter) of the condensate and determine the resulting condensate momentum in\nthe $z$ direction, $P_z(q,\\omega,V_0,t_p)$, where $V_0$ is the peak optical\npotential strength and $t_p$ is the pulse duration. Although the local density\napproximation for the Bogoliubov excitation spectral distribution is a good\napproximation for very low optical intensities, long pulse duration and\nsufficiently large values of the wavevector $q$ of the light-potential, for\nsmall $q$, short duration pulses, or for not-so-low intensities, the local\ndensity perturbative description of the excitation spectrum breaks down badly,\nas shown by our results.",
        "positive": "Toward an anisotropic atom-atom model for the crystalline phases of the\n  molecular S8 compound: We analize two anisotropic atom-atom models used to describe the crystalline\nalpha,beta and gamma phases of S8 crystals, the most stable compound of\nelemental sulfur in solid phases, at ambient pressure and T<=400 K. The\ncalculations are performed via a series of classical molecular dynamics (MD)\nsimulations, with flexible molecular models and using a constant\npressure-constant temperature algorithm for the numerical simulations. All\nintramolecular modes that mix with lattice modes, and are therefore relevant on\nthe onset of structural phase transitions, are taken into account. Comparisons\nwith experimental data and previous results obtained with an isotropic\natom-atom molecular model are also performed."
    },
    {
        "anchor": "Non-conformal coarse-grained potentials for water: Water is a notoriously difficult substance to model both accurately and\nefficiently. Here, we focus on descriptions with a single coarse-grained\nparticle per molecule using the so-called Approximate Non-Conformal (ANC) and\ngeneralized Stockmayer potentials as the starting points. They are fitted using\nthe radial density function and the density of the atomistic SPC/E model by\ndownhill simplex optimization. We compare the results with monatomic water\n(mW), ELBA, as well as with direct Iterative Boltzmann Inversion (IBI) of\nSPC/E. The results show that symmetrical potentials result in non-transferable\nmodels, that is, they need to be reparametrized for new state-points. This\nindicates that transferability may require more complex models. Furthermore,\nthe results also show that the addition of a point dipole is not sufficient to\nmake the potentials accurate and transferable to different temperatures (300\nK-500 K) and pressures without an appropriate choice of properties as targets\nduring model optimization.",
        "positive": "Velocity profiles in shear-banding wormlike micelles: Using Dynamic Light Scattering in heterodyne mode, we measure velocity\nprofiles in a much studied system of wormlike micelles (CPCl/NaSal) known to\nexhibit both shear-banding and stress plateau behavior. Our data provide\nevidence for the simplest shear-banding scenario, according to which the\neffective viscosity drop in the system is due to the nucleation and growth of a\nhighly sheared band in the gap, whose thickness linearly increases with the\nimposed shear rate. We discuss various details of the velocity profiles in all\nthe regions of the flow curve and emphasize on the complex, non-Newtonian\nnature of the flow in the highly sheared band."
    },
    {
        "anchor": "DNA breathing dynamics: Analytic results for distribution functions of\n  relevant Brownian functionals: We investigate DNA breathing dynamics by suggesting and examining several\ndifferent Brownian functionals associated with bubble lifetime and reactivity.\nBubble dynamics is described as an overdamped random walk in the number of\nbroken base pairs. The walk takes place on the Poland-Scheraga free energy\nlandscape. We suggest several probability distribution functions that\ncharacterize the breathing process, and adopt the recently studied backward\nFokker-Planck method and the path decomposition method as elegant and flexible\ntools for deriving these distributions. In particular, for a bubble of an\ninitial size $x_0$, we derive analytical expressions for (i) the distribution\n$P(t_f|x_0)$ of the first-passage time $t_f$, characterizing the bubble\nlifetime, (ii) the distribution $P(A|x_0)$ of the area $A$ till the\nfirst-passage time, providing information about the effective reactivity of the\nbubble to processes within the DNA, (iii) the distribution $P(M)$ of the\nmaximum bubble size $M$ attained before the first-passage time, and (iv) the\njoint probability distribution $P(M,t_m)$ of the maximum bubble size $M$ and\nthe time $t_m$ of its occurrence before the first-passage time. These\ndistributions are analyzed in the limit of small and large bubble sizes. We\nsupplement our analytical predictions with direct numerical simulations of the\nrelated Langevin equation, and obtain a very good agreement in the appropriate\nlimits. The nontrivial scaling behavior of the various quantities analyzed here\ncan, in principle, be explored experimentally.",
        "positive": "Effective charge of cylindrical and spherical colloids immersed in an\n  electrolyte: the quasi-planar limit: We consider the non-linear Poisson-Boltzmann theory for a single cylindrical\nor spherical macro-ion in symmetric 1:1, together with asymmetric 1:2 and 2:1\nelectrolytes. We focus on the regime where $\\kappa a $, the ratio of the\nmacro-ion radius $a$ over the inverse Debye length in the bulk electrolyte, is\nlarge. Analyzing the structure of the analytical expansion emerging from a\nmultiple scale analysis, we uncover a hidden structure for the electrostatic\npotential. This structure, which appears after a heuristic resummation,\nsuggests a new and convenient expansion scheme that we present and work out in\ndetail. We show that novel exact results can thereby be obtained, in particular\npertaining to effective charge properties, in complete agreement with the\ndirect numerical solution to the problem."
    },
    {
        "anchor": "Margination regimes and drainage transition in confined multicomponent\n  suspensions: A mechanistic theory is developed to describe segregation in confined\nmulticomponent suspensions such as blood. It incorporates the two key phenomena\narising in these systems at low Reynolds number: hydrodynamic pair collisions\nand wall-induced migration. In simple shear flow, several regimes of\nsegregation arise, depending on the value of a \"margination parameter\" M. Most\nimportantly, there is a critical value of M below which a sharp \"drainage\ntransition\" occurs: one component is completely depleted from the bulk flow to\nthe vicinity of the walls. Direct simulations also exhibit this transition as\nthe size or flexibility ratio of the components changes.",
        "positive": "Shear thinning and thickening in spherical nanoparticle dispersions: We present a molecular dynamics study of the flow of rigid spherical\nnanoparticles in a simple fluid. We evaluate the viscosity of the dispersion as\na function of shear rate and nanoparticle volume fraction. We observe shear\nthinning behavior at low volume fractions, as the shear rate increases, the\nshear forces overcome the brownian forces, resulting in more frequent and more\nviolent collisions between the nanoparticles. This in turn results in more\ndissipation. We show that in order to be in the shear thinning regime the\nnanoparticle have to order themselves into layers longitudinal to the flow to\nminimize the collisions. As the nanoparticle volume fraction increases there is\nless room to form the ordered layers, consequently as the shear rate increases\nthe nanoparticles collide more which results in turn in shear thickening. Most\ninterestingly, we show that at intermediate volume fractions the system\nexhibits metastability, with successions of ordered and disordered states along\nthe same trajectory. Our results suggest that for nanoparticles in a simple\nfluid the hydro-clustering phenomenon is not present, instead the\norder-disorder transition is the leading mechanism for the transition from\nshear thinning to shear thickening."
    },
    {
        "anchor": "Critical shear rate and torque stability condition for a particle\n  resting on a surface in a fluid flow: We advance a quantitative description of the critical shear rate\n$\\dot{\\gamma_c}$ needed to dislodge a spherical particle resting on a surface\nwith a model asperity in laminar and turbulent fluid flows. We have built a\ncone-plane experimental apparatus which enables measurement of $\\dot{\\gamma_c}$\nover a wide range of particle Reynolds number $Re_p$ from $10^{-3}$ to $1.5\n\\times 10^3$. The condition to dislodge the particle is found to be consistent\nwith the torque balance condition, which { yields a lower $\\dot{\\gamma_c}$\ncompared with} force balance because of the torque component due to drag about\nthe particle center. The data for $Re_p < 0.5$ is in good agreement with\nanalytical calculations of the drag and lift coefficients in the $Re_p\n\\rightarrow 0$ limit. For higher $Re_p$, where analytical results are\nunavailable, the hydrodynamic coefficients are found to approach a constant for\n$Re_p > 1000$. We show that a linear combination of the hydrodynamic\ncoefficients found in the viscous and inertial limits can describe the observed\n$\\dot{\\gamma_c}$ as a function of the particle and fluid properties.",
        "positive": "Bond disorder enhances the information transfer in polar flock: Collection of self-propelled particles (SPPs) exhibit coherent motion and\nshow true long-range order in two-dimensions. Inhomogeneity, in general\ndestroys the usual long-range order of the polar SPPs. We model a system of\npolar self-propelled particles with inhomogeneous interaction strength or bond\ndisorder. The system is studied near the order-to-disorder transition for\ndifferent strengths of the disorder. The nature of phase transition changes\nfrom discontinuous to continuous type by tuning the strength of the disorder.\nThe bond disorder also enhances the ordering near the transition due to the\nformation of a homogeneous flock state for the large disorder. It leads to\nfaster information transfer in the system and enhances the system information\nentropy. Our study gives a new understanding of the effect of intrinsic\ninhomogeneity in the self-propelled particle system."
    },
    {
        "anchor": "Kerr effect as a tool for the investigation of dynamic heterogeneities: We propose a dynamic Kerr effect experiment for the distinction between\ndynamic heterogeneous and homogeneous relaxation in glassy systems. The\npossibility of this distinction is due to the inherent nonlinearity of the Kerr\neffect signal. We model the slow reorientational molecular motion in\nsupercooled liquids in terms of non-inertial rotational diffusion. The Kerr\neffect response, consisting of two terms, is calculated for heterogeneous and\nfor homogeneous variants of the stochastic model. It turns out that the\nexperiment is able to distinguish between the two scenarios. We furthermore\nshow that exchange between relatively 'slow' and 'fast' environments does not\naffect the possibility of frequency-selective modifications. It is demonstrated\nhow information about changes in the width of the relaxation time distribution\ncan be obtained from experimental results.",
        "positive": "Differences of interface and bulk transport properties in polymer\n  field-effect devices: The influence of substrate treatment with self-assembled monolayers and\nthermal annealing was analysed by electrical and structural measurements on\nfield-effect transistors (FETs) and metal-insulator-semiconductor (MIS) diodes\nusing poly(3-hexylthiophene) (P3HT) as a semiconducting polymer and Si/SiO2\nwafers as a substrate. It is found that surface treatment using silanising\nagents like hexamethyldisilazane (HMDS) and octadecyltrichlorosi-lane (OTS) can\nincrease the field-effect mobility by up to a factor of 50, reaching values in\nsaturation of more than 4E-2 cm^2/Vs at room temperature. While there is a\nclear correlation between the obtained field-effect mobility and the contact\nangle of water on the treated substrates, X-ray diffraction and capacitance\nmeasurements on MIS diodes show that structural and electrical properties in\nthe bulk of the P3HT films are not influenced by the surface treatment. On the\nother hand, thermal annealing is found to cause an increase of grain size, bulk\nrelaxation frequency and thereby of the mobility perpendicular to the SiO2/P3HT\ninterface, but has very little influence on the field-effect mobility.\nTemperature dependent investigations on MIS diodes and FETs show that the\ntransport perpendicular to the substrate plane is thermally activated and can\nbe described by hopping in a Gaussian density of states, whereas the\nfield-effect mobility in the substrate plane is almost temperature independent\nover a wide range. This investigations reveal significant differ-ences between\ninterface and bulk transport properties in polymer field-effect devices."
    },
    {
        "anchor": "Particle-resolved topological defects of smectic colloidal liquid\n  crystals in extreme confinement: Confined samples of liquid crystals are characterized by a variety of\ntopological defects and can be exposed to external constraints such as extreme\nconfinements with nontrivial topology. Here we explore the intrinsic structure\nof smectic colloidal layers dictated by the interplay between entropy and an\nimposed external topology. Considering an annular confinement as a basic\nexample, a plethora of competing states is found with nontrivial defect\nstructures ranging from laminar states to multiple smectic domains and arrays\nof edge dislocations which we refer to as Shubnikov states in formal analogy to\nthe characteristic of type-II superconductors. Our particle-resolved results,\ngained by a combination of real-space microscopy of thermal colloidal rods and\nfundamental-measure-based density functional theory of hard anisotropic bodies,\nagree on a quantitative level.",
        "positive": "Comment on \"Probing the equilibrium dynamics of colloidal hard spheres\n  above the mode-coupling glass transition\": In the Letter [PRL 102, 085703 (2009)] Brambilla, et al. claimed to observe\nactivated dynamics in colloidal hard spheres above the critical packing\nfraction of mode coupling theory (MCT). By performing microscopic MCT\ncalculations, we show that polydispersity in their system shifts the critical\npacking fraction above the value determined by van Megen et al. for less\npolydisperse samples, and that the data agree with theory except for, possibly,\nthe highest packing fraction."
    },
    {
        "anchor": "An Improved Process for Fabricating High-Mobility Organic Molecular\n  Crystal Field-Effect Transistors: In this paper we present an improved process for producing elastomer\ntransistor stamps and high-mobility organic field-effect transistors (FETs)\nbased on semiconducting acene molecular crystals. In particular, we have\nremoved the need to use a silanized Si wafer for curing the stamps and to\nhandle a fragile micron-thickness polydimethylsiloxane (PDMS) insulating film\nand laminate it, bubble free, against the PDMS transistor stamp. We find that\ndespite the altered design, rougher PDMS surface, and lamination and\nmeasurement of the device in air, we still achieve electrical mobilities of\norder 10 cm^2/Vs, comparable to the current state of the art in organic FETs.\nOur device shows hole conduction with a threshold voltage of order -9V, which\ncorresponds to a trap density of 1.4 x 10^10 cm^-2.",
        "positive": "Interface relaxation in electrophoretic deposition of polymer chains:\n  Effects of segmental dynamics, molecular weight, and field: Using different segmental dynamics and relaxation, characteristics of the\ninterface growth is examined in an electrophoretic deposition of polymer chains\non a three (2+1) dimensional discrete lattice with a Monte Carlo simulation.\nIncorporation of faster modes such as crankshaft and reptation movements along\nwith the relatively slow kink-jump dynamics seems crucial in relaxing the\ninterface width. As the continuously released polymer chains are driven (via\nsegmental movements) and deposited, the interface width $W$ grows with the\nnumber of time steps $t$, $W \\propto t^{\\beta},$ ($\\beta \\sim 0.4$--$0.8)$,\nwhich is followed by its saturation to a steady-state value $W_s$. Stopping the\nrelease of additional chains after saturation while continuing the segmental\nmovements relaxes the saturated width to an equilibrium value ($W_s \\to W_r$).\nScaling of the relaxed interface width $W_r$ with the driving field $E$, $W_r\n\\propto E^{-1/2}$ remains similar to that of the steady-state $W_s$ width. In\ncontrast to monotonic increase of the steady-state width $W_s$, the relaxed\ninterface width $W_r$ is found to decay (possibly as a stretched exponential)\nwith the molecular weight."
    },
    {
        "anchor": "Slow Dynamics of the High Density Gaussian Core Model: We numerically study crystal nucleation and glassy slow dynamics of the\none-component Gaussian core model (GCM) at high densities. The nucleation rate\nat a fixed supersaturation is found to decrease as the density increases. At\nvery high densities, the nucleation is not observed at all in the time window\naccessed by long molecular dynamics (MD) simulation. Concomitantly, the system\nexhibits typical slow dynamics of the supercooled fluids near the glass\ntransition point. We compare the simulation results of the supercooled GCM with\nthe predictions of mode-coupling theory (MCT) and find that the agreement\nbetween them is better than any other model glassformers studied numerically in\nthe past. Furthermore, we find that a violation of the Stokes-Einstein relation\nis weaker and the non-Gaussian parameter is smaller than canonical\nglassformers. Analysis of the probability distribution of the particle\ndisplacement clearly reveals that the hopping effect is strongly suppressed in\nthe high density GCM. We conclude from these observations that the GCM is more\namenable to the mean-field picture of the glass transition than other models.\nThis is attributed to the long-ranged nature of the interaction potential of\nthe GCM in the high density regime. Finally, the intermediate scattering\nfunction at small wavevectors is found to decay much faster than its self part,\nindicating that dynamics of the large-scale density fluctuations decouples with\nthe shorter-ranged caging motion.",
        "positive": "Evaporation-driven assembly of colloidal particles: Colloidal particles absorbed at the interface of a liquid droplet arrange\ninto unique packings during slow evaporation (Manoharan et al. Science 301 pp\n483-487). We present a numerical and theoretical analysis of the packing\nselection problem. The selection of a unique packing arises almost entirely\nfrom geometrical constraints during the drying."
    },
    {
        "anchor": "Temperature (de)activated patchy colloidal particles: We present a new model of patchy particles in which the interaction sites can\nbe activated or deactivated by varying the temperature of the system. We study\nthe thermodynamics of the system by means of Wertheim's first order\nperturbation theory, and use Flory-Stockmayer theory of polymerization to\nanalyse the percolation threshold. We find a very rich phase behaviour\nincluding lower critical points and reentrant percolation.",
        "positive": "Mapping out the glassy landscape of a mesoscopic elastoplastic model: We develop a mesoscopic model to study the plastic behavior of an amorphous\nmaterial under cyclic loading. The model is depinning-like and driven by a\ndisordered thresholds dynamics which are coupled by long-range elastic\ninteractions. We propose a simple protocol of \"glass preparation\" which allows\nus to mimic thermalisation at high temperature, as well as aging at vanishing\ntemperature. Various levels of glass stabilities (from brittle to ductile) can\nbe achieved by tuning the aging duration. The aged glasses are then immersed\ninto a quenched disorder landscape and serve as initial configurations for\nvarious protocols of mechanical loading by shearing. The dependence of the\nplastic behavior upon monotonous loading is recovered. The behavior under\ncyclic loading is studied for different ages and system sizes. The size and age\ndependence of the irreversibility transition is discussed. A thorough\ncharacterization of the disorder-landscape is achieved through the analysis of\nthe transition graphs, which describe the plastic deformation pathways under\nathermal quasi-static shear. In particular, the analysis of the stability\nranges of the strongly connected components of the transition graphs reveals\nthe emergence of a phase-separation like process associated with the aging of\nthe glass. Increasing the age and hence stability of the initial glass, results\nin a gradual break-up of the landscape of dynamically accessible stable states\ninto three distinct regions: one region centered around the initially prepared\nglass phase, and two additional regions, characterized by well-separated ranges\nof positive and negative plastic strains, each of which is accessible only from\nthe initial glass phase by passing through the stress peak in the forward,\nrespectively, backward shearing directions."
    },
    {
        "anchor": "Integration and characterization of solid wall electrodes in\n  microfluidic devices fabricated in a single photolithography step: We describe the fabrication and characterization of solid 3-dimensional\nelectrodes in direct contact with microfluidic channels, implemented using a\nsingle photolithography step, allowing operation in high-dielectric constant\nmedia. Incorporation and self-alignment of electrodes is achieved by combining\nmicrosolidic approaches with exploitation of the surface tension of low melting\npoint alloys. Thus the metal forms the walls flanking the channel. We show that\nthis approach yields electrodes with a well-defined, reproducible morphology\nand stable electronic properties when in contact with biochemical buffers. By\ncombining calibration of the electric field with free-flow electrophoresis we\nquantify the net solvated charges of small molecules.",
        "positive": "Nonequilibrium and morphological characterizations of Kelvin-Helmholtz\n  instability in compressible flows: We investigate the effects of viscosity and heat conduction on the onset and\ngrowth of Kelvin-Helmholtz instability (KHI) via an efficient discrete\nBoltzmann model. Technically, two effective approaches are presented to\nquantitatively analyze and understand the configurations and kinetic processes.\nOne is to determine the thickness of mixing layers through tracking the\ndistributions and evolutions of the thermodynamic nonequilibrium (TNE)\nmeasures; the other is to evaluate the growth rate of KHI from the slopes of\nmorphological functionals. Physically, it is found that the time histories of\nwidth of mixing layer, TNE intensity, and boundary length show high correlation\nand attain their maxima simultaneously. The viscosity effects are twofold,\nstabilize the KHI, and enhance both the local and global TNE intensities.\nContrary to the monotonically inhibiting effects of viscosity, the heat\nconduction effects firstly refrain then enhance the evolution afterwards. The\nphysical reasons are analyzed and presented."
    },
    {
        "anchor": "Brownian Dynamics Studies on DNA Gel Electrophoresis. I. Numerical\n  Method and Quasi-Periodic Behavior of Elongation-Contraction Motions: Dynamics of individual DNA undergoing constant field gel electrophoresis\n(CFGE) is studied by a Brownian dynamics (BD) simulation method which we have\ndeveloped. The method simulates electrophoresis of DNA in a 3 dimensional (3D)\nspace by a chain of electrolyte beads of hard spheres. Under the constraint\nthat the separation of each pair of bonded beads is restricted to be less than\na certain fixed value, as well as with the excluded volume effect, the Langevin\nequation of motion for the beads is solved by means of the Lagrangian\nmultiplier method. The resultant mobilities, $\\mu$, as a function of the\nelectric field coincide satisfactorily with the corresponding experimental\nresults, once the time, the length and the field of the simulation are properly\nscaled. In relatively strong fields quasi-periodic behavior is found in the\nchain dynamics, and is examined through the time evolution of the radius of the\nlonger principal axis, $R_l(t)$. It is found that the mean width of a peak in\n$R_l(t)$, or a period of one elongation-contraction process of the chain, is\nproportional to the number of beads in the chain, $M$, while the mean period\nbetween two such adjacent peaks is proportional to $M^0$ for large $M$. These\nresults, combined with the observation that the chain moves to the field\ndirection by the distance proportional to $M$ in each elongation-contraction\nmotion, yield $\\mu \\propto M^0$. This explains why CFGE cannot separate DNA\naccording to their size $L (\\propto M)$ for large $L$.",
        "positive": "Dynamic tuning of the director field in liquid crystal shells using\n  block copolymers: When a nematic liquid crystal (LC) is confined on a self-closing spherical\nshell, topological constraints arise with intriguing consequences that depend\ncritically on how the LC is aligned in the shell. We demonstrate reversible\ndynamic tuning of the alignment, and thereby the topology, of nematic LC shells\nstabilized by the nonionic amphiphilic block copolymer Pluronic F127. Deep in\nthe nematic phase, the director is tangential to the interface, but upon\napproaching the temperature TNI of the nematic-isotropic transition, the\ndirector realigns to normal. We link this to a delicate interplay between an\ninterfacial tension that is nearly independent of director orientation, and the\nconfiguration-dependent elastic deformation energy of an LC confined in a\nshell. The process is primarily triggered by the heating-induced reduction of\nthe nematic order parameter, hence realignment temperatures differ by several\ntens of degrees between LCs with high and low TNI, respectively. The\ntemperature of realignment is always lower on the positive-curved shell outside\nthan at the negative-curved inside, yielding a complex topological\nreconfiguration on heating. Complementing experimental investigations with\nmathematical modeling and computer simulations, we identify and investigate\nthree different trajectories, distinguished by their configurations of\ntopological defects in the initial tangential-aligned shell. Our results\nuncover a new aspect of the complex response of LCs to curved confinement,\ndemonstrating that the order of the LC itself can influence the alignment and\nthereby the topology of the system. They also reveal the potential of\namphiphilic block copolymer stabilizers for enabling continuous tunability of\nLC shell configuration, opening doors for in-depth studies of topological\ndynamics as well as novel applications in, e.g., sensing and programmed soft\nactuators."
    },
    {
        "anchor": "Molecular simulation study of the heat capacity of metastable water\n  between 100K and 300K: Molecular simulation study of the heat capacity of metastable water between\n100K and 300K Molecular simulations have been used to study the heat capacity\nof metastable liquid water at low temperature adsorbed on a smooth surface.\nThese calculations aim at modelling water properties measured by experiments\nperformed on water films adsorbed on Vycor nanoporous silica at low\ntemperature. In particular, the study focuses on the non-monotonous variation\nof the heat capacity around between 100 and 300 K.",
        "positive": "Spreading of a granular droplet: The influence of controlled vibrations on the granular rheology is\ninvestigated in a specifically designed experiment. We study experimentally a\nthin granular film spreading under the action of horizontal vibrations. A\nnonlinear diffusion equation is derived theoretically that describes the\nevolution of the deposit shape. A self-similar parabolic shape (the``granular\ndroplet'') and a spreading dynamics are predicted that both agree\nquantitatively with the experimental results. The theoretical analysis is used\nto extract effective dynamic friction coefficients between the base and the\ngranular layer under sustained and controlled vibrations. We derive an\nempirical friction law involving external driving parameters and the layer\nheight to represent our data."
    },
    {
        "anchor": "Crystallization and phase-separation in non-additive binary hard-sphere\n  mixtures: We calculate for the first time the full phase-diagram of an asymmetric\nnon-additive hard-sphere mixture. The non-additivity strongly affects the\ncrystallization and the fluid-fluid phase-separation. The global topology of\nthe phase-diagram is controlled by an effective size-ratio y_{eff}, while the\nfluid-solid coexistence scales with the depth of the effective potential well.",
        "positive": "Flow of lubricated granular material on an inclined plane: We have studied the gravity driven flow of spherical shaped, millimetric\nsized granular material coated with aspherical, micron-sized, near frictionless\nlubricant particles. Experiments were performed on an inclined plane using two\ndifferent sized particles for varying concentrations of the lubricant. The\nparticle volumetric flow rate exhibits a non-monotonic behavior with increasing\nlubricant concentration. It shows an increase at lower lubricant concentration\nfollowed by a decrease at higher lubricant concentration. The lubricant\nparticles adhere to the granular particle surface thereby reducing the\ninter-particle friction. However, presence of lubricant particles at higher\nconcentration damps out inter-particle collision thereby reducing the\ninterparticle momentum transfer. Non-monotonicity in the observed behavior is\nthen conjectured to arise due to competing effects of inter-particle friction\nand inter-particle collision. The present work and the overall observed\nbehavior therein provides a simple experimental system to characterize the\neffects of added lubricant material in pharmaceutical and other relevant\nindustrial applications."
    },
    {
        "anchor": "Directed Paths in a Wedge: Directed paths have been used extensively in the scientific literature as a\nmodel of a linear polymer. Such paths models in particular the conformational\nentropy of a linear polymer and the effects it has on the free energy. These\ndirected models are simplified versions of the self-avoiding walk, but they do\nnevertheless give insight into the phase behaviour of a polymer, and also serve\nas a tool to study the effects of conformational degrees of freedom in the\nbehaviour of a linear polymer. In this paper we examine a directed path model\nof a linear polymer in a confining geometry (a wedge). The main focus of our\nattention is $c_n$, the number of directed lattice paths of length $n$ steps\nwhich takes steps in the North-East and South-East directions and which is\nconfined to the wedge $Y=\\pm X/p$, where $p$ is an integer. In this paper we\nexamine the case $p=2$ in detail, and we determine the generating function\nusing the iterated kernel method. We also examine the asymtotics of $c_n$. In\nparticular, we show that $$ c_n = [0.67874...]\\times 2^{n-1}(1+(-1)^n) +\nO((4/3^{3/4})^{n+o(n)}) + o((4/3^{3/4})^n) $$ where we can determine the\nconstant $0.67874...$ to arbitrary accuracy with little effort.",
        "positive": "Domain growth in cholesteric blue phases: hybrid lattice Boltzmann\n  simulations: Here we review a hybrid lattice Boltzmann algorithm to solve the equations of\nmotion of cholesteric liquid crystals. The method consists in coupling a\nlattice Boltzmann solver for the Navier-Stokes equation to a finite difference\nmethod to solve the dynamical equations governing the evolution of the liquid\ncrystalline order parameter. We apply this method to study the growth of\ncholesteric blue phase domains, within a cholesteric phase. We focus on the\ngrowth of blue phase II and on a thin slab geometry in which the domain wall is\nflat. Our results show that, depending on the chirality, the growing blue phase\nis either BPII with no or few defects, or another structure with hexagonal\nordering. We hope that our simulations will spur further experimental\ninvestigations on quenches in micron-size blue phase samples. The computational\nsize that our hybrid lattice Boltzmann scheme can handle suggest that large\nscale simulations of new generation of blue phase liquid crystal device are\nwithin reach."
    },
    {
        "anchor": "Propagation of interacting force chains in the continuum limit: We study the effect of mergers in the force chain model describing the stress\nprofile in static granular materials. Combining numerical and analytical\ncalculations we show that granular materials do not generally behave in an\nelastic-like manner, however they may under specific conditions, which are\nelaborated. Non-elastic behavior resulting from the non-linearity of the full\nforce chain model is discussed.",
        "positive": "Dynamic oscillatory cluster ordering of self-propelled droplets: We report here a peculiar dynamically ordered state of clustering droplets of\na mixture of organic solvent. There droplets are driven by the solutal\nMarangoni effect on the surface of aqueous surfactant solution. They form\ntemporal ring clusters which start collapsing immediately after its formation.\nThis process is repeated for more than several hours with the period of 5--20\nminutes. We propose an inhomogeneous force model to phenomenologically\nunderstand the basic mechanism of this dynamics, where the forces acting on\neach particle are controlled differently. This droplet system offers a simple,\nnon-biological experimental model for the study of complex dynamical states\nrealized by a group of self-propelled particles."
    },
    {
        "anchor": "Screened electrostatic interactions between clay platelets: An effective pair potential for systems of uniformly charged lamellar\ncolloids in the presence of an electrolytic solution of microscopic co- and\ncounterions is derived. The charge distribution on the discs is expressed as a\ncollection of multipole moments, and the tensors which determine the\ninteractions between these multipoles are derived from a screened Coulomb\npotential. Unlike previous studies of such systems, the interaction energy may\nnow be expressed for discs at arbitrary mutual orientation. The potential is\nshown to be exactly equivalent to the use of linearized Poisson-Boltzmann\ntheory.",
        "positive": "Amino acid characteristics in protein native state structures: We present a geometrical analysis of the protrusion statistics of side chains\nin more than 4,000 high-resolution protein structures. We employ a\ncoarse-grained representation of the protein backbone viewed as a linear chain\nof C{\\alpha} atoms and consider just the heavy atoms of the side chains. We\nstudy the large variety of behaviors of the amino acids based on both\nrudimentary structural chemistry as well as geometry. Our geometrical analysis\nuses a backbone Frenet coordinate system for the common study of all amino\nacids. Our analysis underscores the richness of the repertoire of amino acids\nthat is available to nature to design protein sequences that fit within the\nputative native state folds."
    },
    {
        "anchor": "Orientational Ordering and Dynamics of Rodlike Polyelectrolytes: The interplay between electrostatic interactions and orientational\ncorrelations is studied for a model system of charged rods positioned on a\nchain, using Monte Carlo simulation techniques. It is shown that the coupling\nbrings about the notion of {\\em electrostatic frustration}, which in turn\nresults in: (i) a rich variety of novel orientational orderings such as chiral\nphases, and (ii) an inherently slow dynamics characterized by\nstretched-exponential behavior in the relaxation functions of the system.",
        "positive": "Does the Chapman--Enskog expansion for sheared granular gases converge?: The fundamental question addressed in this paper is whether the partial\nChapman--Enskog expansion $P_{xy}=-\\sum_{k=0}^\\infty \\eta_k ({\\partial\nu_x}/{\\partial y})^{2k+1}$ of the shear stress converges or not for a gas of\ninelastic hard spheres. By using a simple kinetic model it is shown that, in\ncontrast to the elastic case, the above series does converge, the radius of\nconvergence increasing with inelasticity. It is argued that this paradoxical\nconclusion is not an artifact of the kinetic model and can be understood in\nterms of the time evolution of the scaled shear rate in the uniform shear flow."
    },
    {
        "anchor": "Characterization of invariant patterns in a slowly rotated granular\n  tumbler: We report experimental results of the pattern developed by a mixture of two\ntypes of grains in a triangular rotating tumbler operating in the avalanche\nregime. At the centroid of the triangular tumbler an invariant zone appears\nwhere the grains do not move relative to the tumbler. We characterize this\ninvariant zone by its normalized area, $A_i$, and its circularity index as a\nfunction of the normalized filling area $A$. We find a critical filling area so\nthat only for $A>A_c$ invariant zones are obtained. These zones scale as\n$A_i\\sim (A-A_c)^2$ near $A_c$. We have obtained a maximum in the circularity\nindex for $A\\approx 0.8$, for which the shape of the invariant zone is closer\nto a circular one. The experimental results are reproduced by a simple model\nwhich, based on the surface position, accounts for all the possible straight\nlines within the triangle that satisfy the condition of constant $A$. We have\nobtained an analytic expression for the contour of the invariant zone.",
        "positive": "Shear Destruction of Frictional Aging and Memory: We simultaneously measure the static friction and the real area of contact\nbetween two solid bodies. Under static conditions both quantities increase\nlogarithmically in time, a phenomenon coined aging. Indeed, frictional strength\nis traditionally considered equivalent to the real area of contact. Here we\nshow that this equivalence breaks down when a static shear load is applied\nduring aging. The addition of such a shear load accelerates frictional aging\nwhile the aging rate of the real area of contact is unaffected. Moreover, a\nnegative static shear - pulling instead of pushing - slows frictional aging,\nbut similarly does not affect the aging of contacts. The origin of this shear\neffect on aging is geometrical. When shear load is increased, minute relative\ntilts between the two blocks prematurely erase interfacial memory prior to\nsliding, negating the effect of aging. Modifying the loading point of the\ninterface eliminates these tilts and as a result frictional aging rate becomes\ninsensitive to shear. We also identify a secondary memory-erasure effect that\nremains even when all tilts are eliminated and show that this effect can be\nleveraged to accelerate aging by cycling between two static shear loads."
    },
    {
        "anchor": "Dynamics of wrinkles on a vesicle in external flow: Recent experiments by Kantsler et. al. (2007) have shown that the\nrelaxational dynamics of a vesicle in external elongation flow is accompanied\nby the formation of wrinkles on a membrane. Motivated by these experiments we\npresent a theory describing the dynamics of a wrinkled membrane. Formation of\nwrinkles is related to the dynamical instability induced by negative surface\ntension of the membrane. For quasi-spherical vesicles we perform analytical\nstudy of the wrinkle structure dynamics. We derive the expression for the\ninstability threshold and identify three stages of the dynamics. The scaling\nlaws for the temporal evolution of wrinkling wavelength and surface tension are\nestablished and confirmed numerically.",
        "positive": "DEM simulation of soil-tool interaction under extraterrestrial\n  environmental effects: In contrast to terrestrial environment, the harsh lunar environment\nconditions include lower gravity acceleration, ultra-high vacuum and high (low)\ntemperature in the daytime (night-time). This paper focuses on the effects of\nthose mentioned features on soil cutting tests, a simplified excavation test,\nto reduce the risk of lunar excavation missions. Soil behavior and blade\nperformance were analyzed under different environmental conditions. The results\nshow that: (1) the cutting resistance and the energy consumption increase\nlinearly with the gravity. The bending moment has a bigger increasing rate in\nlow gravity fields due to a decreasing moment arm; (2) the cutting\nresistance,energy consumption and bending moment increase significantly because\nof the raised soil strength on the lunar environment, especially in low gravity\nfields. Under the lunar environment, the proportions of cutting resistance,\nbending moment and energy consumption due to the effect of the van der Waals\nforces are significant. Thus, they should be taken into consideration when\nplanning excavations on the Moon. Therefore, considering that the maximum\nfrictional force between the excavator and the lunar surface is proportional to\nthe gravity acceleration, the same excavator that works efficiently on the\nEarth may not be able to work properly on the Moon."
    },
    {
        "anchor": "Unsaturated wet granular flows over a rough incline: frictional and\n  cohesive rheology: Multi-phase flows encountered in nature or in industry, exhibit non trivial\nrheological properties, that can be understood better thanks to model materials\nand appropriate rheometers. Here, we use model unsaturated granular materials:\nassemblies of frictional spherical particles bonded by a small quantity of a\nwetting liquid, over a rough inclined plane. Our results show steady uniform\nflows for a wide range of parameters (the inclination angle and the mass\nflow-rate). A theoretical model, based on the Mohr-Coulomb yield criterion\nextended to inertial flows: $\\tau$ = $\\tau$c + $\\mu$(I)P, in which $\\tau$c and\n$\\mu$(I) are the cohesion stress and the internal friction coefficient\nrespectively, gives predictions in quantitative agreement with experimental\nmeasurements only when one considers that dry and wet samples have\nstraightforwardly different internal friction commonly described by the\nso-called $\\mu$(I)-rheology. The liquid bridges bounding grains not only induce\ncohesion, but modify the internal friction of the wet assemblies.",
        "positive": "Irrational mode locking in quasiperiodic systems: A model for ac-driven systems, based on the\nTang-Wiesenfeld-Bak-Coppersmith-Littlewood automaton for an elastic medium,\nexhibits mode-locked steps with frequencies that are irrational multiples of\nthe drive frequency, when the pinning is spatially quasiperiodic. Detailed\nnumerical evidence is presented for the large-system-size convergence of such a\nmode-locked step. The irrational mode locking is stable to small thermal noise\nand weak disorder. Continuous time models with irrational mode locking and\npossible experimental realizations are discussed."
    },
    {
        "anchor": "Stabilization of straight longitudinal dune under bimodal wind with\n  large directional variation: It has been observed that the direction in which a sand dune extends its\ncrest line depends on seasonal variation of wind direction; when the variation\nis small, the crest line develops more or less perpendicularly to the mean wind\ndirection to form a transverse dune with some undulation. In the case of\nbimodal wind with a large relative angle, however, the dune extends its crest\nalong the mean wind direction and evolves into an almost straight longitudinal\ndune. Motivated by these observations, we investigate the dynamical stability\nof isolated dunes using the crest line model, where the dune dynamics is\nrepresented by its crest line motion. First, we extend the previous linear\nstability analysis under the unidirectional wind to the case with non-zero\nslant angle between the wind direction and the normal direction of the crest\nline, and show that the stability diagram does not depend on the slant angle.\nSecondly, we examine how the linear stability is affected by the seasonal\nchanges of wind direction in the case of bimodal wind with equal strength and\nduration. For the transverse dune, we find that the stability is virtually the\nsame with that for the unidirectional wind as long as the dune evolution during\na season is small. On the other hand, in the case of the longitudinal dune, the\ndispersions of the growth rates for the perturbation are drastically different\nfrom those of the unidirectional wind, and we find that the largest growth rate\nis always located at $k = 0$. This is because the growth of the perturbation\nwith $k \\ne 0$ is canceled by the alternating wind from opposite sides of the\ncrest line even though it grows during each duration period of the bimodal\nwind.",
        "positive": "Green-Kubo approach to the average swim speed in active Brownian systems: We develop an exact Green-Kubo formula relating nonequilibrium averages in\nsystems of interacting active Brownian particles to equilibrium\ntime-correlation functions. The method is applied to calculate the\ndensity-dependent average swim speed, which is a key quantity entering coarse\ngrained theories of active matter. The average swim speed is determined by\nintegrating the equilibrium autocorrelation function of the interaction force\nacting on a tagged particle. Analytical results are validated using Brownian\ndynamics simulations."
    },
    {
        "anchor": "Elastic and viscous properties of nematic dimer CB7CB: We present a comprehensive set of measurements of optical, dielectric,\ndiamagnetic, elastic and viscous properties in the nematic (N) phase formed by\na liquid crystalline dimer. The studied dimer, 1,7-bis-4-(4-cyanobiphenyl)\nheptane (CB7CB), is composed of two rigid rod-like cyanobiphenyl segments\nconnected by a flexible aliphatic link with seven methyl groups. CB7CB and\nother nematic dimers are of interest due to their tendency to adopt bent\nconfigurations and to form two states possessing a modulated nematic director\nstructure, namely, the twist bend nematic, NTB, and the oblique helicoidal\ncholesteric, ChOH, which occurs when the achiral dimer is doped with a chiral\nadditive and exposed to an external electric or magnetic field. We characterize\nthe material parameters as functions of temperature in the entire temperature\nrange of the N phase, including the pre-transitional regions near the N-NTB and\nN-to-isotropic (I) transitions. The splay constant K11 is determined by two\ndirect and independent techniques, namely, detection of the Frederiks\ntransition and measurement of director fluctuation amplitudes by dynamic light\nscattering (DLS). The bend K33 and twist K22 constants are measured by DLS. K33\nbeing the smallest of the three constants, shows a strong non-monotonous\ntemperature dependence with a negative slope in both N-I and N-NTB\npretransitional regions. The measured ratio K11/K22 is larger than 2 in the\nentire nematic temperature range. The orientational viscosities associated with\nsplay, twist and bend fluctuations in the N phase are comparable to those of\nnematics formed by rod-like molecules. All three show strong temperature\ndependence, increasing sharply near the N-NTB transition.",
        "positive": "The depletion force in a bi-disperse granular layer: We demonstrate the effect of the depletion force in experiments and\nsimulations of vertically vibrated mixtures of large and small steel spheres.\nThe system exhibits size segregation and a large increase in the pair\ncorrelation function of the large spheres for short distances that can be\naccurately described using a combination of the depletion potential derived for\nequilibrium colloidal systems and a Boltzmann factor. The Boltzmann factor\ndefines an effective temperature for the system, which we compare to other\nmeasures of the temperature."
    },
    {
        "anchor": "Formation and field-driven dynamics of nematic spheroids: Emerging technologies based on liquid crystal (LC) materials increasingly\nleverage the presence of nanoscale defects, unlike the canonical application of\nLCs -- LC displays. The inherent nanoscale characteristics of LC defects\npresent both significant opportunities and barriers for the application of this\nfascinating class of materials. Simulation-based approaches to the study of the\neffects of confinement and interface anchoring conditions on LC domains has\nresulted in significant progress over the past decade, where simulations are\nnow able to access experimentally-relevant micron-scales while simultaneously\ncapturing nanoscale defect structures. In this work, continuum simulations were\nperformed in order to study the dynamics of micron-scale nematic LC droplets of\nvarying spheroidal geometry. Nematic droplets are one of the simplest\ninherently defect-containing LC structures and are also relevant to\npolymer-dispersed LC-based \"smart\" window technology. Simulation results\ninclude nematic phase formation and external field-switching dynamics of\ndroplets ranging in shape from oblate to prolate. Results include both\nqualitative and quantitative insight into the complex coupling of nanoscale\ndefect dynamics and structure transitions to micron-scale reorientation.\nDynamic mechanisms are presented and related to structural transitions in LC\ndefects present in the droplet. Droplet-scale metrics including order\nparameters and response times are determined for a range of\nexperimentally-accessible electric field strengths. These results have both\nfundamental and technological relevance, in that increased understanding of LC\ndynamics in the presence of defects is a key barrier to continued advancement\nin the field.",
        "positive": "Absorption/Expulsion of Oligomers and Linear Macromolecules in a Polymer\n  Brush: The absorption of free linear chains in a polymer brush was studied with\nrespect to chain size $L$ and compatibility $\\chi$ with the brush by means of\nMonte Carlo (MC) simulations and Density Functional Theory (DFT) /\nSelf-Consistent Field Theory (SCFT) at both moderate, $\\sigma_g = 0.25$, and\nhigh, $\\sigma_g = 1.00$, grafting densities using a bead-spring model.\nDifferent concentrations of the free chains $0.0625 \\le \\phi_o \\le 0.375$ are\nexamined. Contrary to the case of $\\chi = 0$ when all species are almost\ncompletely ejected by the polymer brush irrespective of their length $L$, for\n$\\chi < 0$ we find that the degree of absorption (absorbed amount) $\\Gamma(L)$\nundergoes a sharp crossover from weak to strong ($\\approx 100%$) absorption,\ndiscriminating between oligomers, $1\\le L\\le 8$, and longer chains. For a\nmoderately dense brush, $\\sigma_g = 0.25$, the longer species, $L > 8$,\npopulate predominantly the deep inner part of the brush whereas in a dense\nbrush $\\sigma_g = 1.00$ they penetrate into the \"fluffy\" tail of the dense\nbrush only. Gyration radius $R_g$ and end-to-end distance $R_e$ of absorbed\nchains thereby scale with length $L$ as free polymers in the bulk. Using both\nMC and DFT/SCFT methods for brushes of different chain length $32 \\le N \\le\n256$, we demonstrate the existence of unique {\\em critical} value of\ncompatibility $\\chi = \\chi^{c}<0$. For $\\chi^{c}(\\phi_o)$ the energy of free\nchains attains the {\\em same} value, irrespective of length $L$ whereas the\nentropy of free chain displays a pronounced minimum. At $\\chi^{c}$ all density\nprofiles of absorbing chains with different $L$ intersect at the same distance\nfrom the grafting plane. The penetration/expulsion kinetics of free chains into\nthe polymer brush after an instantaneous change in their compatibility $\\chi$\ndisplays a rather rich behavior. We find three distinct regimes of penetration\nkinetics of free chains regarding the length $L$: I ($1\\le L\\le 8$), II ($8 \\le\nL \\le N$), and III ($L > N$), in which the time of absorption $\\tau$ grows with\n$L$ at a different rate. During the initial stages of penetration into the\nbrush one observes a power-law increase of $\\Gamma \\propto t^\\alpha$ with power\n$\\alpha \\propto -\\ln \\phi_o$ whereby penetration of the free chains into the\nbrush gets {\\em slower} as their concentration rises."
    },
    {
        "anchor": "Statistics of non-affine defect precursors: tailoring defect densities\n  in colloidal crystals using external fields: Coarse-graining atomic displacements in a solid produces both local affine\nstrains and \"non-affine\" fluctuations. Here we study the equilibrium dynamics\nof these coarse grained quantities to obtain space-time dependent correlation\nfunctions. We show how a subset of these thermally excited, non-affine\nfluctuations act as precursors for the nucleation of lattice defects and\nsuggest how defect probabilities may be altered by an {\\it experimentally\nrealisable} \"external\" field conjugate to the global non-affinity parameter.\nOur results are amenable to verification in experiments on colloidal crystals\nusing commonly available holographic laser tweezer and video microscopy\ntechniques, and may lead to simple ways of controlling the defect density of a\ncolloidal solid.",
        "positive": "Metabolically Efficient Codes in The Retina: We tested the hypothesis that the neural code of retinal ganglion cells is\noptimized to transmit visual information at minimal metabolic cost. Under a\nbroad ensemble of light patterns, ganglion cell spike trains consisted of\nsparse, precise bursts of spikes. These bursts were viewed as independent\nneural symbols. The noise in each burst was measured via repeated presentation\nof the visual stimulus, and the energy cost was estimated from the total charge\nflow in a biophysically realistic model of ganglion cell spiking. Given these\ncosts and noise, the theory of efficient codes predicts an optimal distribution\nof symbol usage. Symbols that are either noisy or metabolically costly are\nsuppressed in this optimal code. We found excellent qualitative and\nquantitative agreement with the measured distribution of burst sizes for\nganglion cells in the tiger salamander retina."
    },
    {
        "anchor": "Granular materials composed of shape-anisotropic grains: Granulate physics has made considerable progress during the past decades in\nthe understanding of static and dynamic properties of large ensembles of\ninteracting macroscopic particles, including the modeling of phenomena like\njamming, segregation and pattern formation, the development of related\nindustrial applications or traffic flow control. The specific properties of\nsystems composed of shape-anisotropic (elongated or flattened) particles have\nattracted increasing interest in recent years. Orientational order and\nself-organization are among the characteristic phenomena that add to the\nspecial features of granular matter of spherical or irregular particles. An\noverview of this research field is given.",
        "positive": "Coarse Graining Nonisothermal Microswimmer Suspensions: We investigate coarse-grained models of suspended self-thermophoretic\nmicroswimmers. Upon heating, the Janus spheres, with hemispheres made of\ndifferent materials, induce a heterogeneous local solvent temperature that\ncauses the self-phoretic particle propulsion.\n  Starting from atomistic molecular dynamics simulations, we verify the\ncoarse-grained description of the fluid in terms of a local molecular\ntemperature field, and its role for the particle's thermophoretic\nself-propulsion and hot Brownian motion.\n  The latter is governed by effective nonequilibrium temperatures, which are\nmeasured from simulations by confining the particle position and orientation.\nThey are theoretically shown to remain relevant for any further spatial\ncoarse-graining towards a hydrodynamic description of the entire suspension as\na homogeneous complex fluid."
    },
    {
        "anchor": "Flow pattern in the vicinity of self-propelling hot Janus particles: We study the temperature field and the resulting flow pattern in the vicinity\nof a heated metal-capped Janus particle. If its thickness exceeds about 10 nm,\nthe cap forms an isotherm and the flow pattern comprises a quadrupolar term\nthat decays with the square of the inverse distance 1/r^2. For much thinner\ncaps the velocity varies as 1/r^3. These findings could be relevant for\ncollective effects in dense suspensions and for the circular tracer motion\nobserved recently in the vicinity of a tethered Janus particle.",
        "positive": "Estimation of Persistence Lengths of Semiflexible Polymers: Insight from\n  Simulations: The persistence length of macromolecules is one of their basic\ncharacteristics, describing their intrinsic local stiffness. However, it is\ndifficult to extract this length from physical properties of the polymers,\ndifferent recipes may give answers that disagree with each other. Monte Carlo\nsimulations are used to elucidate this problem, giving a comparative discussion\nof two lattice models, the self-avoiding walk model extended by a bond bending\nenergy, and bottle-brush polymers described by the bond fluctuation model. The\nconditions are discussed under which a description of such macromolecules by\nKratky-Porod worm-like chains holds, and the question to what extent the\npersistence length depends on external conditions (such as solvent quality) is\nconsidered. The scattering function of semiflexible polymers is discussed in\ndetail, a comparison to various analytic treatments is given, and an outlook to\nexperimental work is presented."
    },
    {
        "anchor": "Variation of ionic conductivity in a plastic-crystalline mixture: Ionically-conducting plastic crystals are possible candidates for solid-state\nelectrolytes in energy-storage devices. Interestingly, the admixture of larger\nmolecules to the most prominent molecular PC electrolyte, succinonitrile, was\nshown to drastically enhance its ionic conductivity. Therefore, binary mixtures\nseem to be a promising way to tune the conductivity of such solid-state\nelectrolytes. However, to elucidate the general mechanisms of ionic charge\ntransport in plastic crystals and the influence of mixing, a much broader data\nbase is needed. In the present work, we investigate mixtures of two well-known\nplastic-crystalline systems, cyclohexanol and cyclooctanol, to which 1 mol% of\nLi ions were added. Applying differential scanning calorimetry and dielectric\nspectroscopy, we present a thorough investigation of the phase behavior and the\nionic and dipolar dynamics of this system. All mixtures reveal\nplastic-crystalline phases with corresponding orientational glass-transitions.\nMoreover, their conductivity seems to be dominated by the \"revolving-door\"\nmechanism, implying a close coupling between the ionic translational and the\nmolecular reorientational dynamics of the surrounding plastic-crystalline\nmatrix. In contrast to succinonitrile-based mixtures, there is no strong\nvariation of this coupling with the mixing ratio.",
        "positive": "Double-mode relaxation of highly deformed vesicles: Lipid vesicles are known to undergo complex conformational transitions, but\nit remains challenging to systematically characterize non-equilibrium membrane\nshape dynamics. Here, we report the direct observation of lipid vesicle\nrelaxation from highly deformed shapes using a Stokes trap. Vesicle shape\nrelaxation is described by two distinct characteristic time scales governed by\nthe bending modulus and membrane tension. Interestingly, experimental results\nare consistent with a viscoelastic model of a deformed membrane. Overall, these\nresults show that vesicle relaxation is governed by an interplay between\nmembrane elastic moduli, surface tension, and vesicle deflation."
    },
    {
        "anchor": "Glassy dynamics in thermally-activated list sorting: Sorting the integers 1 through $N$ into an ordered list is a simple task that\ncan be done rapidly. However, using an algorithm based on the\nthermally-activated pairwise exchanges of neighboring list elements, we find\nsorting can display many features of a glass, even for lists as small as $N =\n5$. This includes memory and rejuvenation effects during aging --- two\nhallmarks of glassy dynamics that have been difficult to reproduce in standard\nglass simulations.",
        "positive": "Thermal dephasing and the echo effect in a confined Bose-Einstein\n  condensate: It is shown that thermal fluctuations of the normal component induce\ndephasing -- reversible damping of the low energy collective modes of a\nconfined Bose-Einstein condensate. The dephasing rate is calculated for the\nisotropic oscillator trap, where Landau damping is expected to be suppressed.\nThis rate is characterized by a steep temperature dependence, and it is weakly\namplitude dependent.\n  In the limit of large numbers of bosons forming the condensate, the rate\napproaches zero. However, for the numbers employed by the JILA group, the\ncalculated value of the rate is close to the experimental one. We suggest that\na reversible nature of the damping caused by the thermal dephasing in the\nisotropic trap can be tested by the echo effect. A reversible nature of Landau\ndamping is also discussed, and a possibility of observing the echo effect in an\nanisotropic trap is considered as well. The parameters of the echo are\ncalculated in the weak echo limit for the isotropic trap. Results of the\nnumerical simulations of the echo are also presented."
    },
    {
        "anchor": "Model of coarsening and vortex formation in vibrated granular rods: Neicu and Kudrolli observed experimentally spontaneous formation of the\nlong-range orientational order and large-scale vortices in a system of vibrated\nmacroscopic rods. We propose a phenomenological theory of this phenomenon,\nbased on a coupled system of equations for local rods density and tilt. The\ndensity evolution is described by modified Cahn-Hilliard equation, while the\ntilt is described by the Ginzburg-Landau type equation. Our analysis shows\nthat, in accordance to the Cahn-Hilliard dynamics, the islands of the ordered\nphase appear spontaneously and grow due to coarsening. The generic vortex\nsolutions of the Ginzburg-Landau equation for the tilt correspond to the\nvortical motion of the rods around the cores which are located near the centers\nof the islands.",
        "positive": "Formation of molecules in an expanding Bose-Einstein condensate: A mean field theory of expanding hybrid atom-molecule Bose-Einstein\ncondensates is applied to the recent MPI experiments on ${}^{87}$Rb that\ndemonstrated the formation of ultracold molecules due to Feshbach resonance.\nThe subsequent dissociation of the molecules is treated using a non-mean-field\nparametric approximation. The latter method is also used in determining optimal\nconditions for the formation of molecular BEC"
    },
    {
        "anchor": "Defect-Mediated Relaxation in the Random Tiling Phase of a Binary\n  Mixture: Birth, Death and Mobility of an Atomic Zipper: This paper describes the mechanism of defect-mediated relaxation in a\ndodecagonal square-triangle random tiling phase exhibited by a simulated binary\nmixture of soft discs in 2D. We examine the internal transitions within the\nelementary mobile defect (christened the 'zipper') that allow it to move, as\nwell as the mechanisms by which the zipper is created and annihilated. The\nstructural relaxation of the random tiling phase is quantified and we show that\nthis relaxation is well described by a model based on the distribution of\nwaiting times for each atom to be visited by the diffusing zipper. This system,\nrepresenting one of the few instances where a well defined mobile defect is\ncapable of structural relaxation, can provide a valuable test case for general\ntheories of relaxation in complex and disordered materials.",
        "positive": "Structural changes in block copolymers: coupling of electric field and\n  mobile ions: We consider the coupling between an external electric field and dissociated\nions embedded in anisotropic polarizable media such as block copolymers. We\nargue that the presence of such ions can induce strong morphological changes\nand even lead to a structural phase transition. We investigate, in particular,\ndiblock copolymers in the body centered cubic (bcc) phase. In pure dielectric\nmaterials (no free charges), a dielectric breakdown is expected to occur for\nlarge enough electric fields, preempting any structural phase transition. On\nthe other hand, dissociated ions can induce a phase transition for fields of\nabout 10 V/$\\mu$m or even lower. This transition is from an insulator state,\nwhere charges are preferentially localized inside bcc spherical domains, to a\nconducting state where charges can move along the long axis of oriented\ncylinders (forming a hexagonal phase). The cylinders diameter is small and is\ndetermined by the volume fraction of the minority copolymer component. The\nstrength of this mechanism can be tuned by controlling the amount of free ions\npresent as is observed by our experiments. These theoretical predictions\nsupport recent experimental findings on the bcc to hexagonal phase transition\nin copolymer systems."
    },
    {
        "anchor": "Conservation Laws for Crystal of Topological Defects: Stable array of point defects was generated in nematic liquid crystal. Point\ndefects with topological charge of +1 and -1 (hedgehogs) were generated in\nvertically aligned liquid crystal cell. The hedgehogs were arranged in square\nor hexagonal arrays, and the shape of defect, such as radial or circular\nhedgehogs, were under the control of delicately patterned electrodes. Base on\nthe two-dimensional defect array discovered in experiments, three-dimensional\ncrystals of defects were postulated. The flux of the liquid crystal director\nfield was summarized for each unit cell. The analysis showed that the crystal\nstructure is periodic and stable if the total flux in a unit cell is zero. The\nsurface and bulk topological charges of each unit cells were analyzed. The\nsummation of topological charges of a unit cell obeys the topological rules of\na homeotropic droplet. The hidden conservation laws of flux and topological\ncharges in a soft crystal of defects were discovered, which can be implemented\nin templates for self-assembled micro-structure and tissue design. Most\nimportant of all, the conservation laws may answer why natural structures and\ntissues grow in to a particular shape and form.",
        "positive": "Lane formation in a driven attractive fluid: We investigate non-equilibrium lane formation in a generic model of a fluid\nwith attractive interactions, that is, a two-dimensional Lennard-Jones (LJ)\nfluid composed of two particle species driven in opposite directions.\nPerforming Brownian Dynamics (BD) simulations for a wide range of parameters,\nsupplemented by a stability analysis based on dynamical density functional\ntheory (DDFT), we identify generic features of lane formation in presence of\nattraction, including structural properties. In fact, we find a variety of\nstates (as compared to purely repulsive systems), as well as a close relation\nbetween laning and long wavelength instabilities of the homogeneous phase such\nas demixing and condensation."
    },
    {
        "anchor": "Collective states of active particles with elastic dipolar interactions: Many types of mammalian cells exert active contractile forces and\nmechanically deform their elastic substrate, to accomplish biological functions\nsuch as cell migration. These substrate deformations provide a mechanism by\nwhich cells can sense other cells, leading to long range mechanical intercell\ninteractions and possible self organization. Here, we treat cells as noisy\nmotile particles that exert contractile dipolar stresses on elastic substrates\nas they move. By combining this minimal model for the motility of individual\ncells with a linear elastic model that accounts for substrate mediated cell\ncell interactions, we examine emergent collective states that result from the\ninterplay of cell motility and long range elastic dipolar interactions. In\nparticular, we show that particles self assemble into flexible, motile chains\nwhich can cluster to form diverse larger scale compact structures with polar\norder. By computing key structural and dynamical metrics, we distinguish\nbetween the collective states at weak and strong elastic interactions, as well\nas at low and high motility. We also show how these states are affected by\nconfinement, an important characteristic of the complex mechanical\nmicroenvironment inhabited by cells. Our model predictions are generally\napplicable to active matter with dipolar interactions ranging from biological\ncells to synthetic colloids endowed with electric or magnetic dipole moments.",
        "positive": "Sensitivity of the stress response function to packing preparation: A granular assembly composed of a collection of identical grains may pack\nunder different microscopic configurations with microscopic features that are\nsensitive to the preparation history. A given configuration may also change in\nresponse to external actions such as compression, shearing etc. We show using a\nmechanical response function method developed experimentally and numerically,\nthat the macroscopic stress profiles are strongly dependent on these\npreparation procedures. These results were obtained for both two and three\ndimensions. The method reveals that, under a given preparation history, the\nmacroscopic symmetries of the granular material is affected and in most cases\nsignificant departures from isotropy should be observed. This suggests a new\npath toward a non-intrusive test of granular material constitutive properties."
    },
    {
        "anchor": "Defects in Crystalline Packings of Twisted Filament Bundles: II.\n  Dislocations and Grain Boundaries: Twisted and rope-like assemblies of filamentous molecules are common and\nvital structural elements in cells and tissue of living organisms. We study the\nintrinsic frustration occurring in these materials between the two-dimensional\norganization of filaments in cross section and out-of-plane interfilament twist\nin bundles. Using non-linear continuum elasticity theory of columnar materials,\nwe study the favorable coupling of twist-induced stresses to the presence of\nedge dislocations in the lattice packing of bundles, which leads to a\nrestructuring of the ground-state order of these materials at intermediate\ntwist. The stability of dislocations increases as both the degree of twist and\nlateral bundle size grow. We show that in ground states of large bundles,\nmultiple dislocations pile up into linear arrays, radial grain boundaries,\nwhose number and length grows with bundle twist, giving rise to a rich class of\n\"polycrystalline\" packings.",
        "positive": "Phase separation on the sphere: Patchy particles and self-assembly: Motivated by observations of heterogeneous domain structure on the surface of\ncells, we consider a minimal model to describe the dynamics of phase separation\non the surface of a spherical particle. Finite-size effects on the curved\nparticle surface lead to the formation of long-lived, metastable states for\nwhich the density is distributed in patches over the particle surface. We study\nthe time evolution and stability of these states as a function of both the\nparticle size and the thermodynamic parameters. Finally, by connecting our\nfindings with studies of patchy particles, we consider the implications for\nself-assembly in many-particle systems."
    },
    {
        "anchor": "Modelling imbibition processes in heterogeneous porous media: Imbibition is a commonly encountered multiphase problem in various fields,\nand exact prediction of imbibition processes is a key issue for better\nunderstanding capillary flow in heterogeneous porous media. In this work, a\nnumerical framework for describing imbibition processes in porous media with\nmaterial heterogeneity is proposed to track the moving wetting front with the\nhelp of a partially saturated region at the front vicinity. A new interface\ntreatment, named the interface integral method, is developed here, combined\nwith which the proposed numerical model provides a complete framework for\nimbibition problems. After validation of the current model with existing\nexperimental results of one-dimensional imbibition, simulations on a series of\ntwo-dimensional cases are analysed with the presences of multiple porous\nphases. The simulations presented here not only demonstrate the suitability of\nthe numerical framework on complex domains but also present its feasibility and\npotential for further engineering applications involving imbibition in\nheterogeneous media.",
        "positive": "Internal lipid bilayer friction coefficient from equilibrium canonical\n  simulations: A fundamental result in the theory of Brownian motion is the\nEinstein-Sutherland relation between mobility and diffusion constant. Any\nclassical linear response transport coefficient obeys a similar\nEinstein-Helfand relation. We show in this work how to derive the interleaflet\nfriction coefficient of lipid bilayer by means of an adequate generalisation of\nthe Einstein relation. Special attention must be paid in practical cases to the\nconstraints on the system center of mass position that must be enforced when\ncoupling the system to thermostat."
    },
    {
        "anchor": "Fluid mechanics of mosaic ciliated tissues: In tissues as diverse as amphibian skin and the human airway, the cilia that\npropel fluid are grouped in sparsely distributed multiciliated cells (MCCs). We\ninvestigate fluid transport in this \"mosaic\" architecture, with emphasis on the\ntrade-offs that may have been responsible for its evolutionary selection. Live\nimaging of MCCs in embryos of the frog $Xenopus~laevis$ shows that cilia\nbundles behave as active vortices that produce a flow field accurately\nrepresented by a local force applied to the fluid. A coarse-grained model that\nself-consistently couples bundles to the ambient flow reveals that hydrodynamic\ninteractions between MCCs limit their rate of work so that when the system size\nis large compared to a single MCC, they best shear the tissue at low area\ncoverage, a result that mirrors findings for other sparse distributions such as\ncell receptors and leaf stomata.",
        "positive": "Mean-field model of interaction between bright vortex solitons in\n  Bose-Einstein condensates: Using the explicit numerical solution of the axially-symmetric\nGross-Pitaevskii equation we study the dynamics of interaction among vortex\nsolitons in a rotating matter-wave bright soliton train in a radially trapped\nand axially free Bose-Einstein condensate to understand certain features of the\nexperiment by Strecker et al.[2002 Nature 417 150]. In a soliton train,\nsolitons of opposite phase (phase delta = pi) repel and stay apart without\nchanging shape; solitons with delta = 0 attract, interact and coalesce, but\neventually come out; solitons with a general delta usually repel but interact\ninelastically by exchanging matter. We study and suggest future experiments\nwith vortex solitons."
    },
    {
        "anchor": "Homogenization of elastomers filled with liquid inclusions: The\n  small-deformation limit: This paper presents the derivation of the homogenized equations that describe\nthe macroscopic mechanical response of elastomers filled with liquid inclusions\nin the setting of small quasistatic deformations. The derivation is carried out\nfor materials with periodic microstructure by means of a two-scale asymptotic\nanalysis. The focus is on the non-dissipative case when the elastomer is an\nelastic solid, the liquid making up the inclusions is an elastic fluid, the\ninterfaces separating the solid elastomer from the liquid inclusions are\nelastic interfaces featuring an initial surface tension, and the inclusions are\ninitially $n$-spherical ($n=2,3$) in shape. Remarkably, in spite of the\npresence of local residual stresses within the inclusions due to an initial\nsurface tension at the interfaces, the macroscopic response of such filled\nelastomers turns out to be that of a linear elastic solid that is free of\nresidual stresses and hence one that is simply characterized by an effective\nmodulus of elasticity $\\bar{\\textbf{L}}$. What is more, in spite of the fact\nthat the local moduli of elasticity in the bulk and the interfaces do not\npossess minor symmetries (due to the presence of residual stresses and the\ninitial surface tension at the interfaces), the resulting effective modulus of\nelasticity $\\bar{\\textbf{L}}$ does possess the standard minor symmetries of a\nconventional linear elastic solid, that is,\n$\\bar{L}_{ijkl}=\\bar{L}_{jikl}=\\bar{L}_{ijlk}$. As a first application,\nnumerical results are worked out and analyzed for the effective modulus of\nelasticity of isotropic suspensions of incompressible liquid $2$-spherical\ninclusions of monodisperse size embedded in an isotropic incompressible\nelastomer.",
        "positive": "Timed material self-assembly controlled by circadian clock proteins: Active biological molecules present a powerful, yet largely untapped,\nopportunity to impart autonomous regulation to materials. Because these systems\ncan function robustly to regulate when and where chemical reactions occur, they\nhave the ability to bring complex, life-like behavior to synthetic materials.\nHere, we achieve this design feat by using functionalized circadian clock\nproteins, KaiB and KaiC, to engineer time-dependent crosslinking of colloids.\nThe resulting material self-assembles with programmable kinetics, producing\nmacroscopic changes in material properties, via molecular assembly of KaiB-KaiC\ncomplexes. We show that colloid crosslinking depends strictly on the\nphosphorylation state of KaiC, with kinetics that are synced with KaiB-KaiC\ncomplexing. Our microscopic image analyses and computational models indicate\nthat the stability of colloidal super-structures depends sensitively on the\nnumber of Kai complexes per colloid connection. Consistent with our model\npredictions, a high concentration stabilizes the material against dissolution\nafter a robust self-assembly phase, while a low concentration allows circadian\noscillation of material structure. This work introduces the concept of\nharnessing biological timers to control synthetic materials; and, more\ngenerally, opens the door to using protein-based reaction networks to endow\nsynthetic systems with life-like functional properties."
    },
    {
        "anchor": "Field-driven dynamical demixing of binary mixtures: We consider mixtures of two species of spherical colloidal particles that\ndiffer in their hydrodynamic radii, but are otherwise identical, in the\npresence of an external field. Since the particle-particle and particle-field\ninteractions are the same for both species, they are completely mixed in the\nthermodynamic limit in the presence of any static field. Here, we combine\nBrownian Dynamics and Dynamic Density Functional theory of fluids to show that\nfor sufficiently large differences in the hydrodynamic radius of the particles\n(and corresponding differences in their electrophoretic mobilities) dynamical\ndemixing is observed. These demixed states are transient but, under certain\nconditions, packing effects compromise the relaxation towards the thermodynamic\nstates and the lifetime of the demixed phases increases significantly.",
        "positive": "Effect of Variable Surrounding on Species Creation: We construct a model of speciation from evolution in an ecosystem consisting\nof a limited amount of energy recources. The species posses genetic\ninformation, which is inherited according to the rules of the Penna model of\ngenetic evolution. The increase in number of the individuals of each species\ndepends on the quality of their genotypes and the available energy resources.\nThe decrease in number of the individuals results from the genetic death or\nreaching the maximum age by the individual. The amount of energy resources is\nrepresented by a solution of the differential logistic equation, where the\ngrowth rate of the amount of the energy resources has been modified to include\nthe number of individuals from all species in the ecosystem under\nconsideration. We observe that small evolutionary changes of the inherited\ngenetic information lead to spontaneous bursts of the evolutionary activity\nwhen many new species may appear in a short period."
    },
    {
        "anchor": "The dynamics of colloids in a narrow channel driven by a non-uniform\n  force: Using Brownian dynamics simulations, we investigate the dynamics of colloids\nconfined in two-dimensional narrow channels driven by a non-uniform force F(y).\nWe considered linear-gradient, parabolic and delta-like driving-force profiles.\nThis driving force induces melting of the colloidal solid (i.e., shear-induced\nmelting), and the colloidal motion experiences a transition from elastic to\nplastic regime with increasing F. For intermediate F (i.e., in the transition\nregion) the response of the system, i.e., the distribution of the velocities of\nthe colloidal chains, in general does not coincide with the profile of the\ndriving force F(y), and depends on the magnitude of F, the width of the channel\nand the density of colloids. For example, we show that the onset of plasticity\nis first observed near the boundaries while the motion in the central region is\nelastic. This is explained by: (i) (in)commensurability between the chains due\nto the larger density of colloids near the boundaries, and (ii) the gradient in\nF. Our study provides a deeper understanding of the dynamics of colloids in\nchannels and could be accessed in experiments on colloids (or in dusty plasma)\nwith, e.g., asymmetric channels or in the presence of a gradient potential\nfield.",
        "positive": "Development of anomalous diffusion among crowding proteins: In cell membranes, proteins and lipids diffuse in a highly crowded and\nheterogeneous landscape, where aggregates and dense domains of proteins or\nlipids obstruct the path of diffusing molecules. In general, hindered motion\ngives rise to anomalous transport, though the nature of the onset of this\nbehavior is still under debate and difficult to investigate experimentally.\nHere, we present a systematic study where proteins bound to supported lipid\nmembranes diffuse freely in two dimensions, but are increasingly hindered by\nthe presence of other like proteins. In our model system, the surface coverage\nof the protein avidin on the lipid bilayer is well controlled by varying the\nconcentration of biotinylated lipid anchors. Using fluorescence correlation\nspectroscopy (FCS), we measure the time correlation function over long times\nand convert it to the mean-square displacement of the diffusing proteins. Our\napproach allows for high precision data and a clear distinction between\nanomalous and normal diffusion. It enables us to investigate the onset of\nanomalous diffusion, which takes place when the area coverage of membrane\nproteins increases beyond approximately 5%. This transition region exhibits\npronounced spatial heterogeneities. Increasing the packing fraction further,\ntransport becomes more and more anomalous, manifested in a decrease of the\nexponent of subdiffusion."
    },
    {
        "anchor": "Topological Order in Densely Packed Anisotropic Colloids: The existence of topological order is frequently associated with strongly\ncoupled quantum matter. Here, we demonstrate the existence of topological\nphases in classical systems of densely packed, hard, anisotropic polyhedrally\nshaped colloidal particles. We show that previously reported transitions in\ndense packings lead to the existence of topologically ordered thermodynamic\nphases, which we show are stable away from the dense packing limit. Our work\nexpands the library of known topological phases, whose experimental realization\ncould provide new means for constructing plasmonic materials that are robust in\nthe presence of fluctuations.",
        "positive": "Compacting an assembly of soft balls far beyond the jammed state:\n  insights from 3D imaging: Very soft grain assemblies have unique shape-changing capabilities that allow\nthem to be compressed far beyond the rigid jammed state by filling void spaces\nmore effectively. However, accurately following the formation of these systems\nby monitoring the creation of new contacts, the changes in grain shape, and\nmeasuring grain-scale stresses is challenging. We developed an experimental\nmethod overtaking these challenges and connecting their microscale behavior to\ntheir macroscopic response. By tracking the local strain energy during\ncompression, we reveal a transition from granular-like to continuous-like\nmaterial. Mean contact geometry is shown to vary linearly with the packing\nfraction, which is supported by a mean field approximation. We also validate a\ntheoretical framework which describes the compaction from a local view. Our\nexperimental framework provides insights into the granular micro-mechanisms and\nopens new perspectives for rheological analysis of highly deformable grain\nassemblies in various fields ranging from biology to engineering."
    },
    {
        "anchor": "Supercoiling Enhances DNA Mobility by Reducing Threadings and\n  Entanglements: DNA is increasingly employed for bio and nanotechnology thanks to its\nexquisite versatility and designability. Most of its use is limited to\nlinearised and torsionally relaxed DNA but non-trivial architectures and\ntorsionally constrained -- or supercoiled -- DNA plasmids are largely\nneglected; this is partly due to the limited understanding of how supercoiling\naffects the rheology of entangled DNA. To address this open question we perform\nlarge scale Molecular Dynamics (MD) simulations of entangled solutions of DNA\nplasmids modelled as twistable chains. We discover that, contrarily to what\ngenerally assumed in the literature, larger supercoiling increases the average\nsize of plasmids in the entangled regime. At the same time, we discover that\nthis is accompanied by an unexpected increase of diffusivity. We explain our\nfindings as due to a decrease in inter-plasmids threadings and entanglement",
        "positive": "Geometric approach to mechanical design principles in continuous elastic\n  sheets: Using a geometric formalism of elasticity theory we develop a systematic\ntheoretical method for controlling and manipulating the mechanical response of\nslender solids to external loads. We formally express global mechanical\nproperties associated with non-euclidean thin sheets, and interpret the\nexpressions as inverse problem for designing desired mechanical properties. We\nshow that by wisely designing geometric frustration, extreme mechanical\nproperties can be encoded into a material using accessible experimental\ntechniques. To test the methodology we derive a family of geometries that\nresult with anomalous mechanical behavior such as tunable, an-harmonic, and\neven vanishing rigidities. The presented formalism can be discretized and thus\nopens a new pathway for the design of both continuum and discrete solids and\nstructures."
    },
    {
        "anchor": "LCPOM: Precise Reconstruction of Polarized Optical Microscopy Images of\n  Liquid Crystals: When viewed with a cross-polarized optical microscope (POM), liquid crystals\ndisplay interference colors and complex patterns that depend on the material's\nmicroscopic orientation. That orientation can be manipulated by application of\nexternal fields, which provides the basis for applications in optical display\nand sensing technologies. The color patterns themselves have a high information\ncontent. Traditionally, however, calculations of the optical appearance of\nliquid crystals have been performed by assuming that a single-wavelength light\nsource is employed, and reported in a monochromatic scale. In this work, the\noriginal Jones matrix method is extended to calculate the colored images that\narise when a liquid crystal is exposed to a multi-wavelength source. By\naccounting for the material properties, the visible light spectrum and the CIE\ncolor matching functions, we demonstrate that the proposed approach produces\ncolored POM images that are in quantitative agreement with experimental data.\nResults are presented for a variety of systems, including radial, bipolar, and\ncholesteric droplets, where results of simulations are compared to experimental\nmicroscopy images. The effects of droplet size, topological defect structure,\nand droplet orientation are examined systematically. The technique introduced\nhere generates images that can be directly compared to experiments, thereby\nfacilitating machine learning efforts aimed at interpreting LC microscopy\nimages, and paving the way for the inverse design of materials capable of\nproducing specific internal microstructures in response to external stimuli.",
        "positive": "A rationale for mesoscopic domain formation in biomembranes: Cell plasma membranes display a dramatically rich structural complexity\ncharacterized by functional sub-wavelength domains with specific lipid and\nprotein composition. Under favorable experimental conditions, patterned\nmorphologies can also be observed in vitro on model systems such as supported\nmembranes or lipid vesicles. Lipid mixtures separating in liquid-ordered and\nliquid-disordered phases below a demixing temperature play a pivotal role in\nthis context. Protein-protein and protein-lipid interactions also contribute to\nmembrane shaping by promoting small domains or clusters. Such phase separations\ndisplaying characteristic length-scales falling in-between the nanoscopic,\nmolecular scale on the one hand and the macroscopic scale on the other hand,\nare named mesophases in soft condensed matter physics. In this review, we\npropose a classification of the diverse mechanisms leading to mesophase\nseparation in biomembranes. We distinguish between mechanisms relying upon\nequilibrium thermodynamics and those involving out-of-equilibrium mechanisms,\nnotably active membrane recycling. In equilibrium, we especially focus on the\nmany mechanisms that dwell on an up-down symmetry breaking between the upper\nand lower bilayer leaflets. Symmetry breaking is an ubiquitous mechanism in\ncondensed matter physics at the heart of several important phenomena. In the\npresent case, it can be either spontaneous (domain buckling) or explicit, i.e.,\ndue to an external cause (global or local vesicle bending properties). Whenever\npossible, theoretical predictions and simulation results are confronted to\nexperiments on model systems or living cells, which enables us to identify the\nmost realistic mechanisms from a biological perspective."
    },
    {
        "anchor": "Deformations of the geometry of lipid vesicles: Consider a closed lipid membrane (vesicle), modeled as a two-dimensional\nsurface, described by a geometrical hamiltonian that depends on its extrinsic\ncurvature. The vanishing of its first variation determines the equilibrium\nconfigurations for the system. In this paper, we examine the second variation\nof the hamiltonian about any given equilibrium, using an explicitly surface\ncovariant geometrical approach. We identify the operator which determines the\nstability of equilibrium configurations.",
        "positive": "Rational design and fabrication of versatile active colloidal molecules: Active colloids, also known as artificial microswimmers, are self-propelled\nmicro and nanoparticles that convert uniform sources of fuel (e.g. chemical) or\nuniform external driving fields (e.g. magnetic or electric) into directed\nmotion by virtue of asymmetry in their shape or composition. These materials\nare currently attracting enormous scientific attention for two main end uses.\nFirst, active colloids are prototypical internally driven, out-of-equilibrium\nsystems and their study has led to new emergent material properties, such as\nswarming and living crystallization. Secondly, they hold the promise to be used\nas micro- and nanoscale devices with tremendous potential from medical to\nenvironmental applications. However, the current fabrication of active colloids\nis limited in the programmability of materials, geometry, and modes of motion.\nHere, we use sequential capillarity- assisted particle assembly (sCAPA) to link\nmicrospheres of different materials into clusters of prescribed shapes\n(\"colloidal molecules\") that can actively translate, circulate and rotate\npowered by asymmetric electro-hydrodynamic flows. Further engineering of the\ngeometry and composition provides active colloids that switch motion under\nexternal triggers or perform simple pick-up and transport tasks. Our\nfabrication strategy enables both physicists and engineers to design and create\ncustomized active colloids to explore novel fundamental phenomena in active\nmatter and to investigate materials and propulsion schemes that are compatible\nwith future applications."
    },
    {
        "anchor": "Kinetics of Interior Loop Formation in Semiflexible Chains: Loop formation between monomers in the interior of semiflexible chains\ndescribes elementary events in biomolecular folding and DNA bending. We\ncalculate analytically the interior distance distribution function for\nsemiflexible chains using a mean-field approach. Using the potential of mean\nforce derived from the distance distribution function we present a simple\nexpression for the kinetics of interior looping by adopting Kramers theory. For\nthe parameters, that are appropriate for DNA, the theoretical predictions in\ncomparison to the case are in excellent agreement with explicit Brownian\ndynamics simulations of worm-like chain (WLC) model. The interior looping times\n($\\tau_{IC}$) can be greatly altered in cases when the stiffness of the loop\ndiffers from that of the dangling ends. If the dangling end is stiffer than the\nloop then $\\tau_{IC}$ increases for the case of the WLC with uniform\npersistence length. In contrast, attachment of flexible dangling ends enhances\nrate of interior loop formation. The theory also shows that if the monomers are\ncharged and interact via screened Coulomb potential then both the cyclization\n($\\tau_c$) and interior looping ($\\tau_{IC}$) times greatly increase at low\nionic concentration. Because both $\\tau_c$ and $\\tau_{IC}$ are determined\nessentially by the effective persistence length ($l_p^{(R)}$) we computed\n$l_p^{(R)}$ by varying the range of the repulsive interaction between the\nmonomers. For short range interactions $l_p^{(R)}$ nearly coincides with the\nbare persistence length which is determined largely by the backbone chain\nconnectivity. This finding rationalizes the efficacy of describing a number of\nexperimental observations (response of biopolymers to force and cyclization\nkinetics) in biomolecules using WLC model with an effective persistence length.",
        "positive": "Numerical study of surface-induced reorientation and smectic layering in\n  a nematic liquid crystal: Surface-induced profiles of both nematic and smectic order parameters in a\nnematic liquid crystal, ranging from an orienting substrate to \"infinity\", were\nevaluated numerically on base of an extended Landau theory. In order to obtain\na smooth behavior of the solutions at \"infinity\" a boundary energy functional\nwas derived by linearizing the Landau energy around its equilibrium solutions.\nWe find that the intrinsic wave number of the smectic structure, which plays\nthe role of a coupling between nematic and smectic order, strongly influences\nthe director reorientation. Whereas the smectic order is rapidly decaying when\nmoving away from the surface, the uniaxial nematic order parameter shows an\noscillatory behavior close to the substrate, accompanied by a non-zero local\nbiaxiality."
    },
    {
        "anchor": "Life in the coffee-ring: how evaporation-driven density gradients\n  dictate the outcome of inter-bacterial competition: When a drop dries, it often leaves a ring-shaped stain through a ubiquitous\nphenomenon known as the coffee-ring effect. This also occurs when the liquid\ncontains suspended microbes; evaporation leaves cells at higher concentrations\nin the ring than the drop interior. Using biofilm experiments and cellular\nautomata simulations, we show that the physical structure created by the\ncoffee-ring effect can dramatically alter the outcome of inter-bacterial\ncompetition. We experimentally study this effect using two strains of\n$\\textit{Vibrio cholerae}$ that compete using a contact-dependent killing\nmechanism termed the type 6 secretion system. By creating a heterogeneous\ndensity profile, the coffee-ring effect changes the outcome of competition: the\nbacterial strain that wins in the low-density interior loses in the far denser\nring. Through simulations parameterized with experimentally-determined density\nprofiles, we recapitulate our experimental findings. We examine the role of a\n$\\textit{V. cholerae}$ strain's frequency, its relative efficacy at killing\ncompetitors, and the initial concentration of cells in the droplet in\ndetermining the outcome of competition. By scaling from individual cellular\ninteractions to overall changes in strain frequency, our work demonstrates how\nthe coffee-ring effect plays a powerful role in structuring microbial\ncommunities, indirectly driving ecological changes in community composition.",
        "positive": "Granular flow through an aperture: influence of the packing fraction: For the last 50 years, the flow of a granular material through an aperture\nhas been intensely studied in gravity-driven vertical systems (e.g. silos and\nhoppers). Nevertheless, in many industrial applications, grains are\nhorizontally transported at constant velocity, lying on conveyor belts or\nfloating on the surface of flowing liquids. Unlike fluid flows, that are\ncontrolled by the pressure, granular flow is not sensitive to the local\npressure but rather to the local velocity of the grains at the outlet. We can\nalso expect the flow rate to depend on the local density of the grains. Indeed,\nvertical systems are packed in dense configurations by gravity but, in\ncontrast, in horizontal systems the density can take a large range of values,\npotentially very small, which may significantly alter the flow rate. In the\npresent article, we study, for different initial packing fractions, the\ndischarge through an orifice of monodisperse grains driven at constant velocity\nby a horizontal conveyor belt. We report how, during the discharge, the packing\nfraction is modified by the presence of the outlet and we analyze how changes\nin the packing fraction induce variations in the flow rate. We observe that\nvariations of packing fraction do not affect the velocity of the grains at the\noutlet and, therefore, we establish that flow-rate variations are directly\nrelated to changes in the packing fraction."
    },
    {
        "anchor": "Mesoscopic Modelling and Simulation of Soft Matter: The deformability of soft condensed matter often requires modelling of\nhydrodynamical aspects to gain quantitative understanding. This, however,\nrequires specialised methods that can resolve the multiscale nature of soft\nmatter systems. We review a number of the most popular simulation methods that\nhave emerged, such as Langevin dynamics, dissipative particle dynamics,\nmulti-particle collision dynamics, sometimes also referred to as stochastic\nrotation dynamics, and the lattice-Boltzmann method. We conclude this review\nwith a short glance at current compute architectures for high-performance\ncomputing and community codes for soft matter simulation.",
        "positive": "Quasi-particle properties and Cooper pairing in trapped Fermi gases: The possibility for the particles in a Fermi gas to emit and reabsorb density\nand spin fluctuations gives rise to an effective mass and to a lifetime of the\nquasi-particles, as well as to an effective pairing interaction which affect in\nan important way the BCS critical temperature. We calculate these effects for a\nspherically symmetric trapped Fermi gas of $\\sim$ 1000 particles. The\ncalculation provides insight on the many-body physics of finite Fermi gases and\nis closely related to similar problems recently considered in the case of\natomic nuclei and neutron stars."
    },
    {
        "anchor": "Magnetically Localizing Heat or Enhancing Equilibration in a Quasi 1D\n  Magnetic Fluid: Using two different configurations of temperature and magnetic field\ngradients, we observed that, in a quasi one-dimensional magnetic fluid,\nmagnetic force either reduces the temperature difference across the sample when\nthe two gradients are parallel to each other (PL), or increase the temperature\ndifference when the two gradients are antiparallel (AP), where the single\nconvection roll in zero field was replaced by two localized flows at the two\nends of the sample cell. This flow structure stops the heat flow of approaching\nto thermal equilibrium in the system, causing the temperature at hot side of\nthe sample cell getting hotter and cold side becoming colder. None of these\nphenomena can be described by the existing theories of magnetically-induced\ninstabilities. The underlying physics for observed results for AP configuration\nhas been proposed as the mechanism to drive a new type of heat engines that has\nmuch higher efficiency than Carnot engines and has no pollution to the\nenvironment, our results point to the potential feasibility of this proposed\nmechanism.",
        "positive": "Activated dynamics and effective temperature in a steady state sheared\n  glass: We conduct nonequilibrium molecular dynamics simulations to measure the shear\nstress, the average inherent structure energy, and the effective temperature\n$T_{eff}$ of a sheared model glass as a function of bath temperature $T$ and\nshear strain rate. For $T$ above the glass transition temperature $T_0$, the\nrheology approaches a Newtonian limit and $T_{eff}$ approaches $T$ as the\nstrain rate approaches zero, while for $T<T_0$, the shear stress approaches a\nyield stress and $T_{eff}$ approaches a limiting value near $T_0$. In the\nshear-dominated regime at high $T$, high strain rate or at low $T$, we find\nthat the shear stress and the average inherent structure energy each collapse\nonto a single curve as a function of $T_{eff}$. This indicates that $T_{eff}$\nis controlling behavior in this regime."
    },
    {
        "anchor": "Rotational dynamics, ionic conductivity, and glass formation in a\n  ZnCl2-based deep eutectic solvent: Glass formation and reorientational motions are widespread, but\noften-neglected features of deep eutectic solvents, although both can be\nrelevant for the technically important ionic conductivity at room temperature.\nHere we investigate these properties for two mixtures of ethylene glycol and\nZnCl2, which were recently considered as superior electrolyte materials for\napplication in zinc-ion batteries. For this purpose, we employed dielectric\nspectroscopy performed in a broad temperature range, extending from the\nsupercooled state at low temperatures up to the liquid phase around room\ntemperature and beyond. We find evidence for a relaxation process arising from\ndipolar reorientation dynamics, which reveals the clear signatures of glassy\nfreezing. This freezing also governs the temperature dependence of the ionic dc\nconductivity. We compare the obtained results with those for deep eutectic\nsolvents that are formed by the same hydrogen-bond donor, ethylene glycol, but\nby two different salts, choline chloride and lithium triflate. The four\nmaterials reveal significantly different ionic and reorientational dynamics.\nMoreover, we find varying degrees of decoupling of rotational dipolar and\ntranslational ionic motions, which partly can be described by a fractional\nDebye-Stokes-Einstein relation. The typical glass-forming properties of these\nsolvents strongly affect their room-temperature conductivity.",
        "positive": "Statistical mechanics of specular reflections from fluctuating membranes\n  and interfaces: We study the density of specular reflection points in the geometrical optics\nlimit when light scatters off fluctuating interfaces and membranes in\nthermodynamic equilibrium. We focus on the statistical mechanics of both\ncapillary-gravity interfaces (characterized by a surface tension) and fluid\nmembranes (controlled by a bending rigidity) in thermodynamic equilibrium in\ntwo dimensions. Building on work by Berry, Nye, Longuet-Higgins and others, we\nshow that the statistics of specular points is fully characterized by three\nfundamental length scales, namely, a correlation length $\\xi$, a microscopic\nlength scale $\\ell$ and the overall size $L$ of the interface or membrane. By\ncombining a scaling analysis with numerical simulations, we confirm the\nexistence of a scaling law for the density of specular reflection points,\n$n_{spec}$, in two dimensions, given by $n_{spec}\\propto\\ell^{-1}$ in the limit\nof thin fluctuating interfaces with the interfacial thickness $\\ell\\ll\\xi_I$.\nThe density of specular reflections thus diverges for fluctuating interfaces in\nthe limit of vanishing thickness and shows no dependance on the interfacial\ncapillary-gravity correlation length $\\xi_I$. Although fluid membranes under\ntension also exhibit a divergence in\n$n_{spec}\\propto\\left(\\xi_M\\ell\\right)^{-1/2}$, the number of specular\nreflections in this case can grow by decreasing the membrane correlation length\n$\\xi_{M}$."
    },
    {
        "anchor": "Superfluid-insulator transition in a moving system of interacting bosons: We analyze stability of superfluid currents in a system of strongly\ninteracting ultra-cold atoms in an optical lattice. We show that such a system\nundergoes a dynamic, irreversible phase transition at a critical phase gradient\nthat depends on the interaction strength between atoms. At commensurate\nfilling, the phase boundary continuously interpolates between the classical\nmodulation instability of a weakly interacting condensate and the equilibrium\nquantum phase transition into a Mott insulator state at which the critical\ncurrent vanishes. We argue that quantum fluctuations smear the transition\nboundary in low dimensional systems. Finally we discuss the implications to\nrealistic experiments.",
        "positive": "Collective enhancement and suppression in dilute Bose-Einstein\n  condensates: The coherent and collective nature of a Bose-Einstein condensate can enhance\nor suppress physical processes. Bosonic stimulation enhances scattering in\nalready occupied states which leads to matter wave amplification, and the\nsuppression of dissipation leads to superfluidity. In this summer school notes\nwe present several experiments where enhancement and suppression have been\nobserved and discuss the common roots of and differences between these\nphenomena."
    },
    {
        "anchor": "Basal force fluctuations and granular rheology: Linking macroscopic\n  descriptions of granular flows to bed forces with implications for monitoring\n  signals: Granular flows are ubiquitous in nature with single flows traversing a wide\nrange of dynamic conditions from initiation to deposition. Basal forces exerted\nby environmental granular flows are responsible for the generation of\nobservable seismic signals. To fully realize the benefit of seismic\nmeasurements, basal granular forces must be linked to macroscopic internal flow\ndynamics across a wide range of flow conditions. We utilize discrete element\nsimulations to observe dry and submerged granular flows under plane-shear and\ninclined flow configurations, relating bulk kinematics and rheology to basal\nforcing signals. We find that regardless of the flow geometry/initiation the\nvariance in basal forcing scales with a local non-dimensional shear-rate (or\ninertial number I), and this scaling tracks four different flow regimes spanned\nby our simulations: (1) an unsteady particle rearrangement regime when\n$I<10^{-3}$, where basal forces are dominated by low frequencies; (2) an\nintermediate regime when $10^{-3}< I<10^{-2}$, where granular temperature is\nisotropic and basal forces start to become noise-like, (3) a transitional\nregime at $10^{-2}<I<10^{-1}$, where the increase in basal tractions with\nincreasing shear-rates stalls as the granular bed dilates, partially destroying\nthe contact network and configurational memory, and (4) a fully collisional\nregime when $I>10^{-1}$, where granular temperature is anisotropic in the\nstream-wise direction, and the signal becomes white noise-like up to a cutoff\nfrequency that is dependent on particle size and shear-rate. This effort\nsuggests that basal forces, recorded in instrumented channels or inverted from\nseismic signals, can be used to interpret complex granular processes in\ngeophysical flows.",
        "positive": "Bulk phase behaviour of binary hard platelet mixtures from density\n  functional theory: We investigate isotropic-isotropic, isotropic-nematic and nematic-nematic\nphase coexistence in binary mixtures of circular platelets with vanishing\nthickness, continuous rotational degrees of freedom and radial size ratios\n$\\lambda$ up to 5. A fundamental measure density functional theory, previously\nused for the one-component model, is proposed and results are compared against\nthose from Onsager theory as a benchmark. For $\\lambda \\leq 1.7$ the system\ndisplays isotropic-nematic phase coexistence with a widening of the biphasic\nregion for increasing values of $\\lambda$. For size ratios $\\lambda \\geq 2$, we\nfind demixing into two nematic states becomes stable and an\nisotropic-nematic-nematic triple point can occur. Fundamental measure theory\ngives a smaller isotropic-nematic biphasic region than Onsager theory and\nlocates the transition at lower densities. Furthermore, nematic-nematic\ndemixing occurs over a larger range of compositions at a given value of\n$\\lambda$ than found in Onsager theory. Both theories predict the same\ntopologies of the phase diagrams. The partial nematic order parameters vary\nstrongly with composition and indicate that the larger particles are more\nstrongly ordered than the smaller particles."
    },
    {
        "anchor": "Vector Formalism for Active Nematics in Two Dimensions: Specific features of two-dimensional nematodynamics give rise to shortfalls\nof the tensor representation of the nematic order parameter commonly used in\ncomputations, especially in theory of active matter. The alternative\nrepresentation in terms of the vector order parameter follows with small\nadjustments the classical director-based theory, but is applicable to 2D\nproblems where both nematic alignment and deviation from the isotropic state\nare variable. Stability analysis of nematic alignment and flow is used as a\ntesting ground. A director-based analysis demonstrates a shortfall of the\nstandard theory, which does not ensure relaxation to equilibrium in a passive\nsystem. It also demonstrates the inadequacy of the director-based description,\nwhich misses a stabilizing effect of perturbations of the modulus ensuring\nstability of a passive system on scales far exceeding the healing length.",
        "positive": "Force heterogeneities in particle assemblies: From order to disorder: The effect of increasing structural disorder on the distribution of contact\nforces P(f), inside three dimensional particle assemblies is systematically\nstudied using computer simulations of model granular packings. Starting from a\nface-centred cubic array, where all contact forces are identical, an increasing\nnumber of defects is introduced into the assembly, after which the system is\nthen allowed to relax into a new mechanically stable state. Three distinct\nprotocols for imposing disorder are compared. A quantitative measure of the\ndisorder is obtained from distributions of the coordination number and\nthree-particle contact angle. The distribution of normal contact forces show\ndramatic qualitative changes with increasing disorder. In the regime where the\ndisorder is relatively weak, the pressure and the lowest normal mode frequency\nscale approximately linearly in the coordination number, with distance from the\ncrystalline state. These results for P(f) are discussed in the context of\njamming phenomena in glassy and granular materials."
    },
    {
        "anchor": "Role of slip between a probe particle and a gel in microrheology: In the technique of microrheology, macroscopic rheological parameters as well\nas information about local structure are deduced from the behavior of\nmicroscopic probe particles under thermal or active forcing. Microrheology\nrequires knowledge of the relation between macroscopic parameters and the force\nfelt by a particle in response to displacements. We investigate this response\nfunction for a spherical particle using the two-fluid model, in which the gel\nis represented by a polymer network coupled to a surrounding solvent via a drag\nforce. We obtain an analytic solution for the response function in the limit of\nsmall volume fraction of the polymer network, and neglecting inertial effects.\nWe use no-slip boundary conditions for the solvent at the surface of the\nsphere. The boundary condition for the network at the surface of the sphere is\na kinetic friction law, for which the tangential stress of the network is\nproportional to relative velocity of the network and the sphere. This boundary\ncondition encompasses both no-slip and frictionless boundary conditions as\nlimits. Far from the sphere there is no relative motion between the solvent and\nnetwork due to the coupling between them. However, the different boundary\nconditions on the solvent and network tend to produce different far-field\nmotions. We show that the far field motion and the force on the sphere are\ncontrolled by the solvent boundary conditions at high frequency and by the\nnetwork boundary conditions at low frequency. At low frequencies compression of\nthe network can also affect the force on the sphere. We find the crossover\nfrequencies at which the effects of sliding of the sphere past the polymer\nnetwork and compression of the gel become important.",
        "positive": "Active Brownian particles can mimic the pattern of the substrate: Active Brownian particles (ABPs) are termed out to be a successful way of\nmodeling the moving microorganism on the substrate. In recent studies, it is\nshown that such organisms can sense the characteristics of the substrate.\nMotivated by such work, we studied the dynamics and the steady state of ABP\nmoving on a substrate with space-dependent activity. On the substrate, some\nregions are marked as high in activity, and other regions are such that\nparticles behave as passive Brownian particles. The system is studied in two\ndimensions with step, sigmoid, Gaussian and cone shape distribution of activity\nprofile on the substrate. The whole interface of the activity profile is\nsymmetrically divided into two regions. This lead to the flow of particles from\nthe active region to the passive region. The final steady state of particle\ndensity profile, polarisation and flux very much follows the structure of the\ninhomogeneous activity and the density in high activity region is lower,\nmaximum at the interface and nearly constant with mean density in the passive\nregion. Further, the steady state density profile for various shapes and\ndesigns on two-dimensional substrates. Hence the collection of ABPs on an\ninhomogeneous substrate can mimic the inhomogeneity of the substrate."
    },
    {
        "anchor": "Structure Formation of Amphiphilic Nanocubes at Rest and Under Shear: We investigate the self-assembly of amphiphilic nanocubes under rest and\nshear using molecular dynamics (MD) simulations and kinetic Monte Carlo (KMC)\ncalculations. These particles combine both interaction and shape anisotropy,\nmaking them valuable models for studying folded proteins and DNA-functionalized\nnanoparticles. The nanocubes can self-assemble into various finite-sized\naggregates ranging from rods to self-avoiding random walks, depending on the\nnumber and placement of the hydrophobic faces. Our study focuses on suspensions\ncontaining multi- and one-patch cubes, with their ratio systematically varied.\nWhen the binding energy is comparable to the thermal energy, the aggregates\nconsist of only few cubes that spontaneously associate/dissociate. However,\nhighly stable aggregates emerge when the binding energy exceeds the thermal\nenergy. Generally, the mean aggregation number of the self-assembled clusters\nincreases with the number of hydrophobic faces and decreases with the fraction\nof one-patch cubes. In sheared suspensions, the more frequent collisions\nbetween nanocube clusters lead to faster aggregation dynamics but also to\nsmaller terminal steady-state mean cluster sizes. The MD and KMC simulations\nare in excellent agreement, and the analysis of the rate kernels enables the\nidentification of the primary mechanisms responsible for the (shear-induced)\ncluster growth and breakup.",
        "positive": "A natural ionic liquid: low molecular mass compounds of aggregate glue\n  droplets on spider orb webs: The aggregate glue of spider orb web is an excellent natural adhesive.\nOrb-weaver spiders use micron-scale aggregate glue droplets to retain prey in\nthe capture spiral silks of their orb web. In aggregate glue droplets, highly\nglycosylated and phosphorylated proteins dissolve in low molecular mass\ncompounds. The aggregate glue droplets show a heterogeneous structural\ndistribution after attaching to the substrate. Although components of the\naggregate glue droplets have been well analyzed and determined in past studies,\nvisualization of the spatial distribution of their chemical components before\nand after their attachment is the key to exploring their adhesion mechanisms.\nHere, we investigated the distribution of low molecular mass compounds and\nglycoproteins in aggregate glue droplets using the in situ measurement methods\nand visualized the role of specific low molecular mass compounds in promoting\nglycoprotein modification in the aggregate glue. The results of the analysis\nsuggest that the constituents of aggregate glue droplets include at least one\nionic liquid: hydrated choline dihydrogen phosphate, while the modification of\nglycoproteins in aggregate glue depends on the concentration of this ionic\nliquid. This natural ionic liquid does not affect the fluorescence activity of\nfluorescent proteins, indicating that proteins of aggregate glue droplets can\nbe dissolved well and maintain the stability of their higher-order structures\nin that ionic liquid. As a natural ionic liquid, aggregate glue droplets from\nthe spider orb webs may be an excellent ionic liquid material model."
    },
    {
        "anchor": "Shape transition from elliptical to cylindrical membrane tubes induced\n  by chiral crescent-shaped protein rods: Proteins often form chiral assembly structures on a biomembrane. However, the\nrole of the chirality in the interaction with an achiral membrane is poorly\nunderstood. Here, the differential behavior between chiral and achiral\ncrescent-shaped protein rods was investigated using meshless membrane\nsimulations. The achiral rods deformed the membrane tube into an elliptical\nshape by stabilizing the edges of the ellipse. In contrast, the chiral rods\nformed a helical assembly that generated a cylindrical membrane tube with a\nconstant radius in addition to the elliptical tube. This helical assembly could\nbe further stabilized by the direct side-to-side attraction between the protein\nrods. These results agree with experimental findings of the constant radius of\nmembrane tubules induced by the Bin/Amphiphysin/Rvs (BAR) superfamily proteins.",
        "positive": "State transition graph of the Preisach model and the role of return\n  point memory: The Preisach model has been useful as a null-model for understanding memory\nformation in periodically driven disordered systems. In amorphous solids for\nexample, the athermal response to shear is due to localized plastic events\n(soft spots). As shown recently by one of us, the plastic response to applied\nshear can be rigorously described in terms of a directed network whose\ntransitions correspond to one or more soft spots changing states. The topology\nof this graph depends on the interactions between soft-spots and when such\ninteractions are negligible, the resulting description becomes that of the\nPreisach model. A first step in linking transition graph topology with the\nunderlying soft-spot interactions is therefore to determine the structure of\nsuch graphs in the absence of interactions. Here we perform a detailed analysis\nof the transition graph of the Preisach model. We highlight the important role\nplayed by return point memory in organizing the graph into a hierarchy of loops\nand sub-loops. Our analysis reveals that the topology of a large portion of\nthis graph is actually not governed by the values of the switching fields that\ndescribe the individual hysteretic behavior of the individual elements, but by\na coarser parameter, a permutation $\\rho$ which prescribes the sequence in\nwhich the individual hysteretic elements change their states as the main\nhysteresis loop is traversed. This in turn allows us to derive combinatorial\nproperties, such as the number of major loops in the transition graph as well\nas the number of states $| \\mathcal{R} |$ constituting the main hysteresis loop\nand its nested subloops. We find that $| \\mathcal{R} |$ is equal to the number\nof increasing subsequences contained in the permutation $\\rho$."
    },
    {
        "anchor": "Diversity of knot solitons in liquid crystals manifested by linking of\n  preimages in torons and hopfions: Topological solitons are knots in continuous physical fields classified by\nnon-zero Hopf index values. Despite arising in theories that span many branches\nof physics, from elementary particles to condensed matter and cosmology, they\nremain experimentally elusive and poorly understood. We introduce a method of\nexperimental and numerical analysis of such localized structures in liquid\ncrystals that, similar to the mathematical Hopf maps, relates all points of the\nmedium's order parameter space to their closed-loop preimages within the\nthree-dimensional solitons. We uncover a surprisingly large diversity of\nnaturally occurring and laser-generated topologically nontrivial solitons with\ndifferently knotted nematic fields, which previously have not been realized in\ntheories and experiments alike. We discuss the implications of the liquid\ncrystal's non-polar nature on the knot soliton topology and how the medium's\nchirality, confinement and elastic anisotropy help to overcome the constrains\nof the Hobart-Derrick theorem, yielding static three-dimensional solitons\nwithout or with additional defects. Our findings will establish chiral nematics\nas a model system for experimental exploration of topological solitons and may\nimpinge on understanding of such nonsingular field configurations in other\nbranches of physics, as well as may lead to technological applications",
        "positive": "Mirror symmetry breaking through an internal degree of freedom leading\n  to directional motion: We analyze here the minimal conditions for directional motion (net flow in\nphase space) of a molecular motor placed on a mirror-symmetric environment and\ndriven by a center-symmetric and time-periodic force field. The complete\ncharacterization of the deterministic limit of the dissipative dynamics of\nseveral realizations of this minimal model, reveals a complex structure in the\nphase diagram in parameter space, with intertwined regions of pinning (closed\norbits) and directional motion. This demonstrates that the mirror-symmetry\nbreaking which is needed for directional motion to occur, can operate through\nan internal degree of freedom coupled to the translational one."
    },
    {
        "anchor": "Non-equilibrium cluster-cluster aggregation in the presence of anchoring\n  sites: Non-equilibrium cluster-cluster aggregation of particles diffusing in or at\nthe cell membrane has been hypothesized to lead to domains of finite size in\ndifferent biological contexts such as lipid rafts, cell adhesion complexes, or\npostsynaptic domains in neurons. In this scenario, the desorption of particles\nbalances a continuous flux to the membrane, imposing a cut-off on possible\naggregate sizes and giving rise to a stationary size distribution. Here, we\ninvestigate the case of non-equilibrium cluster-cluster aggregation in two\ndimensions where diffusing particles and/or clusters remain fixed in space at\nspecific anchoring sites, which should be particularly relevant for synapses\nbut may also be present in other biological or physical systems. Using an\neffective mean-field description of the concentration field around anchored\nclusters, we derive an expression for their average size as a function of\nparameters such as the anchoring site density. We furthermore propose and solve\nappropriate rate equations that allow us to predict the size distributions of\nboth diffusing and fixed clusters. We confirm our results with particle-based\nsimulations, and discuss potential implications for biological and physical\nsystems.",
        "positive": "Non-equilibrium self-assembly of a filament coupled to ATP/GTP\n  hydrolysis: We study the stochastic dynamics of growth and shrinkage of single actin\nfilaments or microtubules taking into account insertion, removal, and ATP/GTP\nhydrolysis of subunits. The resulting phase diagram contains three different\nphases: a rapidly growing phase, an intermediate phase and a bound phase. We\nanalyze all these phases, with an emphasis on the bound phase. We also discuss\nhow hydrolysis affects force-velocity curves. The bound phase shows features of\ndynamic instability, which we characterize in terms of the time needed for the\nATP/GTP cap to disappear as well as the time needed for the filament to reach a\nlength of zero, i.e., (to collapse) for the first time. We obtain exact\nexpressions for all these quantities, which we test using Monte Carlo\nsimulations."
    },
    {
        "anchor": "Detection of nanobubbles between two liquid layers using atomic force\n  microscopy meniscus force-distance measurements: The presence of nanobubbles on lubricant-infused surfaces (LIS) has so far\nbeen overlooked due to the difficulty in detecting them in such a complex\nsystem. We recently showed that anomalously large interfacial slip measured on\nLIS is explained by the presence of nanobubbles. Crucial to drawing this\nconclusion was the use of atomic force microscopy (AFM) force-distance\nspectroscopy to directly image nanobubbles on LIS. This technique provided\nvital direct evidence of the spontaneous nucleation of nanobubbles on\nlubricant-infused hydrophobic surfaces. In this paper, we describe in detail\nthe data collection and analysis of AFM meniscus force measurements on LIS and\nshow how these powerful measurements can quantify both the thickness and\ndistribution of multiple coexisting fluid layers (i.e. gas and oil) over a\nnanostructured surface.",
        "positive": "Lattice Boltzmann simulations of spontaneous flow in active liquid\n  crystals: the role of boundary conditions: Active liquid crystals or active gels are soft materials which can be\nphysically realised e.g. by preparing a solution of cytoskeletal filaments\ninteracting with molecular motors. We study the hydrodynamics of an active\nliquid crystal in a slab-like geometry with various boundary conditions, by\nsolving numerically its equations of motion via lattice Boltzmann simulations.\nIn all cases we find that active liquid crystals can sustain spontaneous flow\nin steady state contrarily to their passive counterparts, and in agreement with\nrecent theoretical predictions. We further find that conflicting anchoring\nconditions at the boundaries lead to spontaneous flow for any value of the\n'activity' parameter, while with unfrustrated anchoring at all boundaries\nspontaneous flow only occurs when the activity exceeds a critical threshold. We\nfinally discuss the dynamic pathway leading to steady state in a few selected\ncases."
    },
    {
        "anchor": "The role of polymer structure on water confinement in\n  poly(N-isopropylacrylamide) dispersions: Poly(N-isopropylacrylamide) (PNIPAM) is a synthetic polymer that is widely\nstudied for its thermoresponsive character. However, recent works also reported\nevidence of a low temperature (protein-like) dynamical transition around 225 K\nin concentrated PNIPAM suspensions, independently of the polymer architecture,\ni.e., both for linear chains and for microgels. In this work, we investigate\nwater-polymer interactions by extensive differential scanning calorimetry (DSC)\nmeasurements of both systems, in order to understand the effect of the\ndifferent topological structures on the solution behaviour, in particular\nregarding crystallization and melting processes. In addition, we compare\nprotiated and deuterated microgels, in both water and deuterated water. The DSC\nresults are complemented by dynamic light scattering experiments, which confirm\nthat the selective isotopic substitution differently affects the solution\nbehaviour. Our findings highlight the important role played by the polymer\narchitecture on the solution behaviour: indeed, microgels turn out to be more\nefficient confining agents, able to avoid water crystallization in a wider\nconcentration range with respect to linear chains. Altogether, the present data\nwill be valuable to interpret future low-temperature investigations of PNIPAM\ndispersions, particularly by neutron scattering experiments.",
        "positive": "Run-and-Tumble-Like Motion of Active Colloids in Viscoelastic Media: Run-and-tumble (RNT) motion is a prominent locomotion strategy employed by\nmany living microorganisms. It is characterized by straight swimming intervals\n(runs), which are interrupted by sudden reorientation events (tumbles). In\ncontrast, directional changes of synthetic microswimmers (active particles,\nAPs) are caused by rotational diffusion, which is superimposed with their\ntranslational motion and thus leads to rather continuous and slow particle\nreorientations. Here we demonstrate that active particles can also perform a\nswimming motion where translational and orientational changes are disentangled,\nsimilar to RNT. In our system, such motion is realized by a viscoelastic\nsolvent and a periodic modulation of the self-propulsion velocity.\nExperimentally, this is achieved using light-activated Janus colloids, which\nare illuminated by a time-dependent laser field. We observe a strong\nenhancement of the effective translational and rotational motion when the\nmodulation time is comparable to the relaxation time of the viscoelastic fluid.\nOur findings are explained by the relaxation of the elastic stress, which\nbuilds up during the self-propulsion, and is suddenly released when the\nactivity is turned off. In addition to a better understanding of active motion\nin viscoelastic surroundings, our results may suggest novel steering strategies\nfor synthetic microswimmers in complex environments."
    },
    {
        "anchor": "Parameterization of hydrodynamic friction in a model for sheared\n  suspensions of rough particles: We propose a method to parameterize a coarse grained model for the\nhydrodynamic friction between nearly touching rough spheres in suspension\nflows. The frictional resistance due to surface roughness primarily alters the\nsliding and rolling modes of motion of rough particles. Stokesian dynamics\nsimulations incorporating a near-field pairwise resistance model accounting for\nthese enhanced frictional modes were employed to compute particle trajectories\nin shear flow. In this model, the resistance to sliding and rolling modes of\nmotion are augmented from a weakly diverging log$(1/h)$ form for smooth spheres\nto a strongly diverging $1/h$ form for rough spheres to account for the\nadditional resistance due to squeezing flows between surface asperities, where\n$h$ is the mean surface separation between particles. We determine new bounds\non the relative magnitude of the augmentations to the resistance to different\nmodes of motion using inequality constraints reflecting the positive\ndefiniteness of the Stokes resistance tensor for a pair of rough particles.\nUsing the simulations of a particle pair in a shear flow, a simple model for\nangular rotation rate of the pair centerline is computed as a function of its\norientation in the shear flow and the free parameters of the hydrodynamic\nresistance model: the friction coupling strength, $\\alpha$, and friction\ncoupling range, $h_0$. Values of $\\alpha$ and $h_0$ for real-world rough\nparticles can then be inferred by matching the pair rotation rate in the model\nto experimental observations when a dilute rough particle suspension is\nsubjected to a linear shear flow. The same model is used to calculate the\nhydrodynamic contribution to the high frequency viscosity of rough particle\nsuspensions. For different $\\alpha$ and $h_0$, we observe that the viscosity\ndiverges differently depending on $h_0$.",
        "positive": "Persistence-Speed Coupling Enhances the Search Efficiency of Migrating\n  Immune Cells: Migration of immune cells within the human body allows them to fulfill their\nmain function of detecting pathogens. Adopting an optimal navigation and search\nstrategy by these cells is of crucial importance to achieve an efficient immune\nresponse. Analyzing the dynamics of dendritic cells in our in vitro experiments\nreveals that the directional persistence of these cells is highly correlated\nwith their migration speed, and that the persistence-speed coupling enables the\nmigrating cells to reduce their search time. We introduce theoretically a new\nclass of random search optimization problems by minimizing the mean\nfirst-passage time (MFPT) with respect to the strength of the coupling between\ninfluential parameters such as speed and persistence length. We derive an\nanalytical expression for the MFPT in a confined geometry and verify that the\ncorrelated motion improves the search efficiency if the mean persistence length\nis sufficiently shorter than the confinement size. In contrast, a positive\npersistence-speed correlation even increases the MFPT at long persistence\nlength regime, thus, such a strategy is disadvantageous for highly persistent\nactive agents."
    },
    {
        "anchor": "Aging is a log-Poisson Process, not a Renewal Process: Aging is a ubiquitous relaxation dynamic in disordered materials. It ensues\nafter a rapid quench from an equilibrium \"fluid\" state into a non-equilibrium,\nhistory-dependent jammed state. We propose a physically motivated description\nthat contrasts sharply with a continuous-time random walk (CTRW) with broadly\ndistributed trapping times commonly used to fit aging data. A renewal process\nlike CTRW proves irreconcilable with the log-Poisson statistic exhibited, for\nexample, by jammed colloids as well as by disordered magnets. A log-Poisson\nprocess is characteristic of the intermittent and decelerating dynamics of\njammed matter usually activated by record-breaking fluctuations (\"quakes\"). We\nshow that such a record dynamics (RD) provides a universal model for aging,\nphysically grounded in generic features of free-energy landscapes of disordered\nsystems.",
        "positive": "Electrical Detection of Self-Assembled Polyelectrolyte Multilayers by a\n  Thin Film Resistor: The build up of polyelectrolyte multilayers (PEMs) was observed by a\nsilicon-on-insulator (SOI) based thin film resistor. Differently charged\npolyelectrolytes adsorbing to the sensor surface result in defined potential\nshifts, which decrease with the number of layers deposited. We model the\nresponse of the device assuming electrostatic screening of polyelectrolyte\ncharges by mobile ions within the PEMs. The Debye screening length inside the\nPEMs was found to be increased compared to the value corresponding to the bulk\nsolution. Furthermore the partitioning of mobile ions between the bulk phase\nand the polyelectrolyte film was employed to calculate the dielectric constant\nof the PEMs and the concentration of mobile charges."
    },
    {
        "anchor": "Capillary-driven flow induced by a stepped perturbation atop a viscous\n  film: Thin viscous liquid films driven by capillarity are well described in the\nlubrication theory through the thin film equation. In this article, we present\nan analytical solution of this equation for a particular initial profile: a\nstepped perturbation. This initial condition allows a linearization of the\nproblem making it amenable to Fourier analysis. The solution is obtained and\ncharacterized. As for a temperature step in the heat equation, self-similarity\nof the first kind of the full evolution is demonstrated and a long-term\nexpression for the excess free energy is derived. In addition, hydrodynamical\nfields are described. The solution is then compared to experimental profiles\nfrom a model system: a polystyrene nanostep above the glass transition\ntemperature which flows due to capillarity. The excellent agreement enables a\nprecise measurement of the capillary velocity for this polymeric liquid,\nwithout involving any numerical simulation. More generally, as these results\nhold for any viscous system driven by capillarity, the present solution may\nprovide a useful tool in hydrodynamics of thin viscous films.",
        "positive": "Absence of `fragility' and mechanical response of jammed granular\n  materials: We perform molecular dynamic (MD) simulations of frictional non-thermal\nparticles driven by an externally applied shear stress. After the system jams\nfollowing a transient flow, we probe its mechanical response in order to\nclarify whether the resulting solid is 'fragile'. We find the system to respond\nelastically and isotropically to small perturbations of the shear stress,\nsuggesting absence of fragility. These results are interpreted in terms of the\nenergy landscape of dissipative systems. For the same values of the control\nparameters, we check the behaviour of the system during a stress cycle.\nIncreasing the maximum stress value, a crossover from a visco-elastic to a\nplastic regime is observed."
    },
    {
        "anchor": "Microscopic processes controlling the Herschel-Bulkley exponent: The flow curve of various yield stress materials is singular as the strain\nrate vanishes, and can be characterized by the so-called Herschel-Bulkley\nexponent $n=1/\\beta$. A mean-field approximation due to Hebraud and Lequeux\n(HL) assumes mechanical noise to be Gaussian, and leads to $\\beta=2$ in rather\ngood agreement with observations. Here we prove that the improved mean-field\nmodel where the mechanical noise has fat tails instead leads to $\\beta=1$ with\nlogarithmic correction. This result supports that HL is not a suitable\nexplanation for the value of $\\beta$, which is instead significantly affected\nby finite dimensional effects. From considerations on elasto-plastic models and\non the limitation of speed at which avalanches of plasticity can propagate, we\nargue that $\\beta=1+1/(d-d_f)$ where $d_f$ is the fractal dimension of\navalanches and $d$ the spatial dimension. Measurements of $d_f$ then supports\nthat $\\beta\\approx 2.1$ and $\\beta\\approx 1.7$ in two and three dimensions\nrespectively. We discuss theoretical arguments leading to approximations of\n$\\beta$ in finite dimensions.",
        "positive": "Short Pulse Dynamics in Strongly Nonlinear Dissipative Granular Chains: We study the energy decay properties of a pulse propagating in a strongly\nnonlinear granular chain with damping proportional to the relative velocity of\nthe grains. We observe a wave disturbance that at low viscosities consists of\ntwo parts exhibiting two entirely different time scales of dissipation. One\npart is an attenuating solitary wave, is dominated by discreteness and\nnonlinearity effects as in a dissipationless chain, and has the shorter\nlifetime. The other is a purely dissipative shocklike structure with a much\nlonger lifetime and exists only in the presence of dissipation. The range of\nviscosities and initial configurations that lead to this complex wave\ndisturbance are explored."
    },
    {
        "anchor": "Energy transfer in nonlinear network models of proteins: We investigate how nonlinearity and topological disorder affect the energy\nrelaxation of local kicks in coarse-grained network models of proteins. We find\nthat nonlinearity promotes long-range, coherent transfer of substantial energy\nto specific, functional sites, while depressing transfer to generic locations.\nRemarkably, transfer can be mediated by the self-localization of discrete\nbreathers at distant locations from the kick, acting as efficient\nenergy-accumulating centers.",
        "positive": "Polymer Complexation: Partially Ionizable Asymmetric Polyelectrolytes: Studies of the thermodynamics of complex coacervation of pairs of symmetric,\nstrongly ionizable, oppositely charged polyelectrolyte chains are abundant. To\ngeneralize such understanding to asymmetric chain lengths and variable\nionizability (chemical charge density), frequently observed in experiments, we\npresent a theoretical framework to analyze the effective charge and size of the\ncomplex and the thermodynamics of complexation of two polyions as a function of\nsuch asymmetries. The free energy ensuing from the Edwards' Hamiltonian\nundergoes variational extremization, and explicitly accounts for the screened\nCoulomb and non-electrostatic interactions among monomers within individual\npolyions and between two polyions. Assuming maximal ion-pair formation of the\ncomplexed part, the system free energy comprising configurational entropy of\nthe polyions and free-ion entropy of the small ions is minimized. The\nthermodynamic drive for complexation is found to increase with the ionizability\nof the symmetric polyions and to be maximum for symmetric chain lengths for\nequally ionizable polyions. The effective charge and size of the complex\nincrease with asymmetry in charge density, where the size can be substantially\nlarger than a collapsed globule found for symmetric chains. The regimes of\nenthalpy- and entropy-driven complexation are found, respectively, for low and\nhigh Coulomb strengths. The crossover strength is found to be strongly\ndependent on the dielectric environment and salt, but marginally dependent on\nthe charge density, thus implying an entropy-driven process at moderate\nstrengths. The key results match the trends in simulations and experiments, and\nare expected to provide insight for asymmetric complexation in real systems."
    },
    {
        "anchor": "Enhanced dispersion in an oscillating array of harmonic traps: Experiment, theory, and simulation are employed to understand the dispersion\nof colloidal particles in a periodic array of oscillating harmonic traps\ngenerated by optical tweezers. In the presence of trap oscillation, a\nnon-monotonic and anisotropic dispersion is observed. Surprisingly, the\nstiffest traps produce the largest dispersion at a critical frequency, and the\nparticles diffuse significantly faster in the direction of oscillation than\nthose undergoing passive Stokes-Einstein-Sutherland diffusion. Theoretical\npredictions for the effective diffusivity of the particles as a function of\ntrap stiffness and oscillation frequency are developed using generalized Taylor\ndispersion theory and Brownian dynamics simulations. Both theory and simulation\ndemonstrate excellent agreement with the experiments, and reveal a new\n``slingshot'' mechanism that predicts a significant enhancement of colloidal\ndiffusion in dynamic external fields.",
        "positive": "Anisotropic elasticity in confocal studies of colloidal crystals: We consider the theory of fluctuations of a colloidal solid observed in a\nconfocal slice. For a cubic crystal we study the evolution of the projected\nelastic properties as a function of the anisotropy of the crystal using\nnumerical methods based on the fast Fourier transform. In certain situations of\nhigh symmetry we find exact analytic results for the projected fluctuations."
    },
    {
        "anchor": "Vorticity phase separation and defect lattices in the isotropic phase of\n  active liquid crystals: We use numerical simulations and linear stability analysis to study the\ndynamics of an active liquid crystal film on a substrate in the regime where\nthe passive system would be isotropic. Extensile activity builds up local\norientational order and destabilizes the quiescent isotropic state above a\ncritical activity value, eventually resulting in spatiotemporal chaotic\ndynamics akin to the one observed ubiquitously in the nematic state. Here we\nshow that tuning substrate friction yields a variety of emergent structures at\nintermediate activity, including lattices of flow vortices with associated\nregular arrangements of topological defects and a new state where flow vortices\ntrap pairs of $+1/2$ defect that chase each other tail. These chiral units\nspontaneously pick the sense of rotation and organize in a hexagonal lattice,\nsurrounded by a diffuse flow of opposite rotation to maintain zero net\nvorticity. The length scale of these emergent structures is set by the\nscreening length $l_\\eta=\\sqrt{\\eta/\\Gamma}$ of the flow, controlled by the\nshear viscosity $\\eta$ and the substrate friction $\\Gamma$, and can be captured\nby simple mode selection of the vortical flows. We demonstrate that the\nemergence of coherent structures can be interpreted as a phase separation of\nvorticity, where friction plays a role akin to that of birth/death processes in\nbreaking conservation of the phase separating species and selecting a\ncharacteristic scale for the patterns. Our work shows that friction provides an\nexperimentally accessible tuning parameter for designing controlled active\nflows.",
        "positive": "Centrifugal compression of soft particle packings - theory and\n  experiment: An exact method is developed for computing the height of an elastic medium\nsubjected to centrifugal compression, for arbitrary constitutive relation\nbetween stress and strain. Example solutions are obtained for power-law media\nand for cases where the stress diverges at a critical strain -- for example as\nrequired by packings composed of deformable but incompressible particles.\nExperimental data are presented for the centrifugal compression of\nthermo-responsive N-isopropylacrylamide (NIPA) microgel beads in water. For\nsmall radial acceleration, the results are consistent with Hertzian elasticity,\nand are analyzed in terms of the Young elastic modulus of the bead material.\nFor large radial acceleration, the sample compression asymptotes to a value\ncorresponding to a space-filling particle volume fraction of unity. Therefore\nwe conclude that the gel beads are incompressible, and deform without\ndeswelling. In addition, we find that the Young elastic modulus of the\nparticulate gel material scales with cross-link density raised to the power\n3.3+-0.8, somewhat larger than the Flory expectation."
    },
    {
        "anchor": "The Radial Hedgehog Solution in the Landau-de Gennes Theory: Effects of\n  the Bulk Potentials: We study equilibrium configurations in spherical droplets of nematic liquid\ncrystal with strong radial anchoring, within the Landau-de Gennes theory with a\nsixth-order bulk potential. The sixth-order potential predicts a bulk biaxial\nphase for sufficiently low temperatures, which the conventional fourth-order\npotential cannot predict. We prove the existence of a radial hedgehog solution,\nwhich is a uniaxial solution with a single isotropic point defect at the\ndroplet centre, for all temperatures and droplet sizes, and prove that there is\na unique radial hedgehog solution for moderately low temperatures, but not deep\nin the nematic phase. We numerically compute critical points of the Landau-de\nGennes free energy with the sixth order bulk potential, with rotational and\nmirror symmetry, and find at least two competing stable critical points: the\nbiaxial torus and split core solutions, which have biaxial regions around the\ncentre, for low temperatures. The size of the biaxial regions increases with\ndecreasing temperature. We also compare the properties of the radial hedgehog\nsolution with the fourth-order and sixth-order potentials respectively, in\nterms of the Morse indices as a function of the temperature and droplet radius;\nthe role of the radial hedgehog solution as a transition state in switching\nprocesses; and compare the bifurcation plots with temperature, with the fourth-\nand sixth-order potentials. Overall, the sixth-order potential has a\nstabilising effect on biaxial critical points and a de-stabilising effect on\nuniaxial critical points and we discover an altogether novel bulk biaxial\ncritical point of the Landau-de Gennes energy with the sixth-order potential,\nfor which the bulk biaxiality is driven by the sixth-order potential.",
        "positive": "Drainage of foam films: A brief review of the classical theory of foam film drainage is presented as\nwell as a new theory accounting for the effect of thickness non-homogeneities\nin the film developed by the film drainage."
    },
    {
        "anchor": "Shear-banding and superdiffusivity in entangled polymer solutions: Using high-resolution confocal rheometry, we study the shear profiles of\nwell-entangled DNA solutions under large amplitude oscillatory shear (LAOS) in\na rectilinear planar shear cell. With increasing Weissenberg number (Wi), we\nobserve successive transitions from normal Newtonian linear shear profiles to\nwall-slip dominant shear profiles and finally to shear-banding profiles at high\nWi. To investigate the microscopic origin of the observed shear banding, we\nstudy the dynamics of micron-sized tracers embedded in DNA solutions.\nSurprisingly, tracer particles in the shear frame exhibit transient\nsuper-diffusivity and strong dynamic heterogeneity. The probability\ndistribution functions of particle displacements follow a power-law scaling at\nlarge displacements, indicating a Levy-walk-type motion, reminiscent of tracer\ndynamics in entangled wormlike micelle solutions and sheared colloidal glasses.\nWe further characterize the length and time scales associated with the abnormal\ndynamics of tracer particles. We hypothesize that the unusual particle dynamics\narise from localized shear-induced chain disentanglement.",
        "positive": "Importance of the ion-pair lifetime in polymer electrolytes: Ion-pairing is commonly considered as a culprit for the reduced ionic\nconductivity in polymer electrolyte systems. However, this simple thermodynamic\npicture should not be taken literally, as ion-pairing is a dynamical\nphenomenon. Here we construct model PEO-LiTFSI systems with different degree of\nion-pairing by tuning solvent polarity, and examine the relation between the\ncation-anion distinct conductivity $\\sigma^\\rm{d}_{+-}$ and the lifetime of\nion-pairs $\\tau_{+-}$ using molecular dynamics simulations. It is found that\nthere exist two distinct regimes where $\\sigma^\\rm{d}_{+-}$ scales with\n$1/\\tau_{+-}$ and $\\tau_{+-}$ respectively, and the latter is a signature of\nlonger-lived ion-pairs which contribute negatively to the total ionic\nconductivity. This suggests that ion-pairs are kinetically different depending\non the solvent polarity, which renders the ion-pair lifetime highly important\nwhen discussing its effect on ion transport in polymer electrolyte systems."
    },
    {
        "anchor": "Structural Color from Solid-State Polymerization-Induced Phase\n  Separation: Structural colors are produced by wavelength-dependent scattering of light\nfrom nanostructures. While living organisms often exploit phase separation to\ndirectly assemble structurally colored materials from macromolecules, synthetic\nstructural colors are typically produced in a two-step process involving the\nsequential synthesis and assembly of building blocks. Phase separation is\nattractive for its simplicity, but applications are limited due to a lack of\nrobust methods for its control. A central challenge is to arrest phase\nseparation at the desired length scale. Here, we show that solid-state\npolymerization-induced phase separation can produce stable structures at\noptical length scales. In this process, a polymeric solid is swollen and\nsoftened with a second monomer. During its polymerization, the two polymers\nbecome immiscible and phase separate. As free monomer is depleted, the host\nmatrix resolidifies and arrests coarsening. The resulting PS-PMMA composites\nhave a blue or white appearance. We compare these biomimetic nanostructures to\nthose in structurally-colored feather barbs, and demonstrate the flexibility of\nthis approach by producing structural color in filaments and large sheets.",
        "positive": "Driven spheres, ellipsoids and rods in explicitly modeled polymer\n  solutions: Understanding the transport of driven nano- and micro-particles in complex\nfluids is of relevance for many biological and technological applications. Here\nwe perform hydrodynamic multiparticle collision dynamics simulations of\nspherical and elongated particles driven through polymeric fluids containing\ndifferent concentrations of polymers. We determine the mean particle velocities\nwhich are larger than expected from Stokes law for all particle shapes and\npolymer densities. Furthermore we measure the fluid flow fields and local\npolymer density and polymer conformation around the particles. We find that\npolymer-depleted regions close to the particles are responsible for an apparent\ntangential slip velocity which accounts for the measured flow fields and\ntransport velocities. A simple two-layer fluid model gives a good match to the\nsimulation results."
    },
    {
        "anchor": "Diffusion in mesoscopic lattice models of amorphous plasticity: We present results on tagged particle diffusion in a meso-scale lattice model\nfor sheared amorphous material in athermal quasi-static conditions. We find a\nshort time diffusive regime and a long time diffusive regime whose diffusion\ncoefficients depend on system size in dramatically different ways. At short\ntime, we find that the diffusion coefficient, $D$, scales roughly linearly with\nsystem length, $D\\sim L^{1.05}$. This short time behavior is consistent with\nparticle-based simulations. The long-time diffusion coefficient scales like\n$D\\sim L^{1.6}$, close to previous studies which found $D\\sim L^{1.5}$.\nFurthermore, we show that the near-field details of the interaction kernel do\nnot affect the short time behavior, but qualitatively and dramatically affect\nthe long time behavior, potentially causing a saturation of the mean-squared\ndisplacement at long times. Our finding of a $D\\sim L^{1.05}$ short time\nscaling resolves a long standing puzzle about the disagreement between the\ndiffusion coefficient measured in particle-based models and meso-scale lattice\nmodels of amorphous plasticity.",
        "positive": "Locally favoured structures and dynamic length scales in a simple\n  glass-former: We investigate the static and dynamic properties of a weakly polydisperse\nhard sphere system in the deeply supercooled state, i.e. at densities higher\nthan that corresponding to the mode-coupling transition. The structural\nanalysis reveals the emergence of icosahedral locally favoured structures,\npreviously only found in trace quantities. We present a new approach to probe\nthe shape of dynamically heterogeneous regions, which is insensitive to\nparticle packing effects that can hamper such analysis. Our results indicate\nthat the shape of the dynamically heterogeneous regions changes only weakly and\nmoreover hint that the often-used four-point correlation length may exhibit a\ngrowth in excess of that which our method identifies. The growth of the size of\nthe dynamically heterogeneous regions appears instead to be in line with the\none of structural and dynamic propensity correlations."
    },
    {
        "anchor": "Mechanical characterization of brain tissue in tension at dynamic strain\n  rates: Mechanical characterization of brain tissue at high loading velocities is\ncrucial for modeling Traumatic Brain Injury (TBI). During severe impact\nconditions, brain tissue experiences compression, tension and shear. Limited\nexperimental data is available for brain tissue in extension at dynamic strain\nrates. In this research, a High Rate Tension Device (HRTD) was developed to\nobtain dynamic properties of brain tissue in extension at strain rates of <\n90/s. In vitro tensile tests were performed to obtain properties of brain\ntissue at strain rates of 30, 60 and 90/s up to 30% strain. The brain tissue\nshowed a stiffer response with increasing strain rates, showing that\nhyperelastic models are not adequate. Specifically, the tensile engineering\nstress at 30% strain was 3.1 +/- 0.49 kPa, 4.3 +/- 0.86 kPa, 6.5 +/- 0.76 kPa\n(mean +/- SD) at strain rates of 30, 60 and 90/s, respectively. Force\nrelaxation tests in tension were also conducted at different strain magnitudes\n(10-60% strain) with the average rise time of 24 ms, which were used to derive\ntime dependent parameters. One-term Ogden, Fung and Gent models were used to\nobtain material parameters from the experimental data. Numerical simulations\nwere performed using a one-term Ogden model to analyze hyperelastic behavior of\nbrain tissue up to 30% strain. The material parameters obtained in this study\nwill help to develop biofidelic human brain finite element models, which can\nsubsequently be used to predict brain injuries under impact conditions and as a\nreconstruction and simulation tool for forensic investigations.",
        "positive": "Visco-elastic drag forces and crossover from no-slip to slip boundary\n  conditions for flow near air-water interfaces: The \"free\" water surface is generally prone to contamination with surface\nimpurities be they surfactants, particles or other surface active agents. The\npresence of such impurities can modify flow boundary near such interfaces in a\ndrastic manner. Here we show that vibrating a small sphere mounted on an AFM\ncantilever near a gas bubble immersed in water, is an excellent probe of\nsurface contamination. Both viscous and elastic forces are exerted by an\nair-water interface on the vibrating sphere even when very low doses of\ncontaminants are present. The viscous drag forces show a cross-over from\nno-slip to slip boundary conditions while the elastic forces show a nontrivial\nvariation as the vibration frequency changes. We provide a simple model to\nrationalize these results and propose a simple way of evaluating the\nconcentration of such surface impurities."
    },
    {
        "anchor": "Tunable dynamics of microtubule based active isotropic gels: We investigate the dynamics of an active gel of bundled microtubules that is\ndriven by clusters of kinesin molecular motors. Upon the addition of ATP, the\ncoordinated action of thousands of molecular motors drives the gel to a highly\ndynamical turbulent-like state that persists for hours and is only limited by\nthe stability of constituent proteins and the availability of the chemical\nfuel. We characterize how enhanced transport and emergent macroscopic flows of\nactive gels depend on relevant molecular parameters, including ATP, kinesin\nmotor, and depletant concentrations, microtubule volume fraction, as well as\nthe stoichiometry of the constituent motor clusters. Our results show that the\ndynamical and structural properties of microtubule based active gels are highly\ntunable. They also indicate existence of an optimal concentration of molecular\nmotors that maximize far-from-equilibrium activity of active isotropic MT gels.",
        "positive": "The $\u03bc(I)$ model and extensions applied to granular material in silo\n  with inserts: Granular material is often handled using silos with inserts in industrial\nprocesses to prevent \"rat-holing\" and similar behaviour, optimise mixing\nbehaviour, and prevent segregation. We study the mass flow rate and the static\nzones of granular silos using the $\\mu(I)$ rheology in the incompressible\nNavier-Stokes equations. We also extend the $\\mu(I)$ model to incorporate\npseudo-dilatancy and nonlocal fluidity. We find that insert shape has a\nsignificant effect on flow rate and static material. We also find that the\neffect of inserts on flow rate is not strongly affected by the extensions,\nwhile the amount of static material is highly dependent on the interactions\nbetween insert shape and extensions. Finally, we find that the effect on flow\nrate varies with insert size, while the amount of static material is not\nsignificantly affected by increasing insert size. These results could provide\nimportant insights for optimising silo design."
    },
    {
        "anchor": "Three dimensional diffusion with helical persistence: We formulate the the problem of persistent diffusion in three dimensions from\nthe perspective of the Frenet--Serret equations. In contrast to one and two\ndimensional systems, in three dimensions persistent diffusion is, in general, a\nthird order process. In this paper we derive a Fokker--Planck equation for the\nprocess and we calculate its effective diffusion constant. We also provide\nexpressions for the asymptotic average displacement of the walk, as well as\nexplicit expressions for the Fourier--Laplace transform of the correlations\nbetween the tangent, normal and binormal vectors of the motion.",
        "positive": "Strongly nonlinear wave dynamics in a chain of polymer coated beads: Strongly nonlinear phononic crystals were assembled from a chain of\nParylene-C coated steel spheres in a polytetrafluoroethylene (PTFE) holder.\nThis system exhibits strongly nonlinear properties and extends the range of\nmaterials supporting \"sonic vacuum\" type behavior. The combination of a high\ndensity core and a soft (low elastic modulus) coating ensures a relatively low\nvelocity of wave propagation. The beads contact interaction caused by the\ndeformation of the Parylene coating can be described as classical nonlinear\nHertz theory despite the viscoelastic nature of the polymer and the high strain\nrate deformation of the contact area. Strongly nonlinear solitary waves excited\nby impacts were investigated experimentally and compared to chains composed of\nuniform steel beads. Fracture of the polumer coating was detected under\nrelatively large pulse amplitude."
    },
    {
        "anchor": "The size and shape of snowflake star polymers in dilute solutions:\n  analytical and numerical approaches: We investigate the conformational properties of a multi-branched polymer\nstructure with a dendrimer-like topology, known as a snowflake polymer. This\npolymer is characterized by two parameters: $f_s$, which represents the\nfunctionality of the central star-like core, and $f$, which represents the\nfunctionality of the side branching points. To analyze the conformational\nproperties, we have employed various approaches, including analytical methods\nbased on direct polymer renormalization and the Wei's approach as well as\nnumerical molecular dynamics simulations. These methods have allowed us to\nestimate a size and shape characteristics of the snowflake polymer as functions\nof $f$ and $f_s$. Our findings consistently demonstrate the effective\ncompactification of the typical polymer conformation as the number of branching\npoints increases. Overall, our study provides valuable insights into the\nconformational behavior of the snowflake polymer and highlights the impact of\nbranching parameters on its overall compactness.",
        "positive": "Effects of partial charge-transfer solute -- solvent interactions in\n  absorption spectra of aromatic hydrocarbons in aqueous and alcoholic\n  solutions: A method for study of charge-transfer interactions between solute molecules\nand solvent based on the comparison of the ratios of spectral shifts of\ndifferent electronic transitions in solute molecules in chemically inert\nsolvent is proposed. The method is applicable to molecules that do not change\ntheir dipole moment on excitation. As an example, a presence of charge transfer\ninteractions in higher electronic states of aromatic hydrocarbons (benzene,\nphenanthrene, and naphthalene) dissolved in water and alcohols was\ndemonstrated."
    },
    {
        "anchor": "Scale invariance in coarsening of binary and ternary fluids: Phase separation in binary and ternary fluids is studied using a two\ndimensional Lattice Gas Automata. The lengths, given by the the first zero\ncrossing point of the correlation function and the total interface length is\nshown to exhibit power law dependence on time. In binary mixtures, our data\nclearly indicate the existence of a regime having more than one length scale\nwhere the coarsening process proceeds through the rupture and reassociation of\ndomains. In ternary fluids; in the case of symmetric mixtures there exists a\nregime with a single length scale having dynamic exponent 1/2, while in\nasymmetric mixtures our data establish the break down of scale invariance.",
        "positive": "Complex scaling approach to the decay of Bose-Einstein condensates: The mean-field dynamics of a Bose-Einstein condensate is studied in presence\nof a microscopic trapping potential from which the condensate can escape via\ntunneling through finite barriers. We show that the method of complex scaling\ncan be used to obtain a quantitative description of this decay process. A\nreal-time propagation approach that is applied to the complex-scaled\nGross-Pitaevskii equation allows us to calculate the chemical potentials and\nlifetimes of the metastably trapped Bose-Einstein condensate. The method is\napplied to a one-dimensional harmonic confinement potential combined with a\nGaussian envelope, for which we compute the lowest symmetric and antisymmetric\nquasibound states of the condensate. A comparison with alternative approaches\nusing absorbing boundary conditions as well as complex absorbing potentials\nshows good agreement."
    },
    {
        "anchor": "Rubber friction: role of the flash temperature: When a rubber block is sliding on a hard rough substrate, the substrate\nasperities will exert time-dependent deformations of the rubber surface\nresulting in viscoelastic energy dissipation in the rubber, which gives a\ncontribution to the sliding friction. Most surfaces of solids have roughness on\nmany different length scales, and when calculating the friction force it is\nnecessary to include the viscoelastic deformations on all length scales. The\nenergy dissipation will result in local heating of the rubber. Since the\nviscoelastic properties of rubber-like materials are extremely strongly\ntemperature dependent, it is necessary to include the local temperature\nincrease in the analysis. At very low sliding velocity the temperature increase\nis negligible because of heat diffusion, but already for velocities of order\n0.01 m/s the local heating may be very important. Here I study the influence of\nthe local heating on the rubber friction, and I show that in a typical case the\ntemperature increase results in a decrease in rubber friction with increasing\nsliding velocity for v > 0.01 m/s. This may result in stick-slip instabilities,\nand is of crucial importance in many practical applications, e.g., for the\ntire-road friction, and in particular for ABS-breaking systems.",
        "positive": "Ideal glass-glass transitions and logarithmic decay of correlations in a\n  simple system: We calculate the ideal-glass-transition line for adhesive hard spheres in the\ntemperature-volume-fraction plane within the framework of the mode-coupling\ntheory. We find two intersecting lines, controlled by the hard-core and the\nadhesive part of the potential respectively, giving rise to two different\nmechanisms for structural arrest. In the glass region we identify the presence\nof a glass-glass-transition line ending in a cusp bifurcation which causes,\neven in the close by liquid region, a logarithmic decay of correlations."
    },
    {
        "anchor": "Anomalous diffusion from Brownian motion with random confinement: We present a model of anomalous diffusion consisting of an ensemble of\nparticles undergoing homogeneous Brownian motion except for confinement by\nrandomly placed reflecting boundaries. For power-law distributed compartment\nsizes, we calculate exact and asymptotic values of the ensemble averaged mean\nsquared displacement and find that it increases subdiffusively, as either a\npower or the logarithm of time. Numerical simulations show that the probability\ndensity function of the displacement is non-Gaussian. We discuss the relevance\nof the model for the analysis of single-particle tracking experiments and its\nrelation to other sources of subdiffusion. In particular we discuss an intimate\nconnection with diffusion on percolation processes.",
        "positive": "Insights from Single-File Diffusion into Cooperativity in Higher\n  Dimensions: Diffusion in colloidal suspensions can be very slow due to the cage effect,\nwhich confines each particle within a short radius on one hand, and involves\nlarge-scale cooperative motions on the other. In search of insight into this\ncooperativity, here the authors develop a formalism to calculate the\ndisplacement correlation in colloidal systems, mainly in the two-dimensional\ncase. To clarify the idea for it, studies are reviewed on cooperativity among\nthe particles in the one-dimensional case, i.e. the single-file diffusion\n(SFD). As an improvement over the celebrated formula by Alexander and Pincus on\nthe mean-square displacement (MSD) in SFD, it is shown that the displacement\ncorrelation in SFD can be calculated from Lagrangian correlation of the\nparticle interval in the one-dimensional case, and also that the formula can be\nextended to higher dimensions. The improved formula becomes exact for large\nsystems. By combining the formula with a nonlinear theory for correlation, a\ncorrection to the asymptotic law for the MSD in SFD is obtained. In the\ntwo-dimensional case, the linear theory gives description of vortical\ncooperative motion."
    },
    {
        "anchor": "Ion pump activity generates fluctuating electrostatic forces in\n  biomembranes: We study the non-equilibrium dynamics of lipid membranes with proteins that\nactively pump ions across the membrane. We find that the activity leads to a\nfluctuating force distribution due to electrostatic interactions arising from\nvariation in dielectric constant across the membrane. By applying a multipole\nexpansion we find effects on both the tension and bending rigidity dominated\nparts of the membranes fluctuation spectrum. We discuss how our model compares\nwith previous studies of force-multipole models.",
        "positive": "Glassiness and Heterogeneous Dynamics in Dense Solutions of Ring\n  Polymers: Understanding how topological constraints affect the dynamics of polymers in\nsolution is at the basis of any polymer theory and it is particularly needed\nfor melts of rings. These polymers fold as crumpled and space-filling objects\nand, yet, they display a large number of topological constraints. To understand\ntheir role, here we systematically probe the response of solutions of rings at\nvarious densities to \"random pinning\" perturbations. We show that these\nperturbations trigger non-Gaussian and heterogeneous dynamics, eventually\nleading to non-ergodic and glassy behaviours. We then derive universal scaling\nrelations for the values of solution density and polymer length marking the\nonset of vitrification in unperturbed solutions. Finally, we directly connect\nthe heterogeneous dynamics of the rings with their spatial organisation and\nmutual interpenetration. Our results suggest that deviations from the typical\nbehaviours observed in systems of linear polymers may originate from\narchitecture-specific (threading) topological constraints."
    },
    {
        "anchor": "Gelling by Heating: We introduce a simple model, a binary mixture of patchy particles, which has\nbeen designed to form a gel upon heating. Due to the specific nature of the\nparticle interactions, notably the number and geometry of the patches as well\nas their interaction energies, the system is a fluid both at high and at low\ntemperatures, whereas at intermediate temperatures the system forms a\nsolid-like disordered open network structure, i.e. a gel. Using molecular\ndynamics we investigate the static and dynamic properties of this system.",
        "positive": "A hard-sphere quasicrystal stabilized by configurational entropy: Due to their aperiodic nature, quasicrystals are one of the least understood\nphases in statistical physics. One significant complication they present in\ncomparison to their periodic counterparts is the fact that any quasicrystal can\nbe realized as an exponentially large number of different tilings, resulting in\na significant contribution to the quasicrystal entropy. Here, we use\nfree-energy calculations to demonstrate that it is this configurational entropy\nwhich stabilizes a dodecagonal quasicrystal in a binary mixture of hard spheres\non a plane. Our calculations also allow us to quantitatively confirm that in\nthis system all tiling realizations are essentially equally likely, with\nfree-energy differences less than 0.0001$k_BT$ per particle -- an observation\nthat could be the related to the observation of only random tilings in soft\nmatter quasicrystals. Owing to the simplicity of the model and its available\ncounterparts in colloidal experiments, we believe that this system is a\nexcellent candidate to achieve the long-awaited quasicrystal self-assembly on\nthe micron scale."
    },
    {
        "anchor": "Equilibrium structures of anisometric, quadrupolar particles confined to\n  a monolayer: We investigate the structural properties of a two-dimensional system of\nellipsoidal particles carrying a linear quadrupole moment in their center.\nThese particles represent a simple model for a variety of uncharged, non-polar\nconjugated organic molecules. Using optimization tools based on ideas of\nEvolutionary Algorithms, we first examine the ground state structures as we\nvary the aspect ratio of the particles and the pressure. Interestingly, we\nfind, besides the intuitively expected T-like configurations, a variety of\ncomplex structures, characterized with up to three different particle\norientations. In an effort to explore the impact of thermal fluctuations, we\nperform constant-pressure Molecular Dynamics simulations within a range of\nrather low temperatures. We observe that ground state structures formed by\nparticles with a large aspect ratio are in particular suited to withstand\nfluctuations up to rather high temperatures. Our comprehensive investigations\nallow for a deeper understanding of molecular or colloidal monolayer\narrangements under the influence of a typical electrostatic interaction on a\ncoarse-grained level.",
        "positive": "State, rate and temperature-dependent sliding friction of elastomers: We present an experimental investigation of the non stationary frictional\nproperties of multicontact interfaces between rough elastomers and rough hard\nglass at low velocities (<= 200 mu m s^{-1}). These systems, for which the\ndeformation contribution to friction is negligible, are shown to exhibit a\nphenomenology which is similar to what is observed for non elastomeric\nmaterials in the same multi-contact configuration, and which are quantitatively\ndescribed by the state- and rate-dependent friction laws. This permits to\nidentify clearly the two contributions to adhesive friction which are mixed in\nsteady sliding: the interfacial shear stress which appears as thermally\nactivated formation and breaking of molecular bonds, and the real area of\ncontact which evolves through viscoelastic creep of the load bearing\nasperities."
    },
    {
        "anchor": "Anisotropic Particles Strengthen Granular Pillars under Compression: We probe the effects of particle shape on the global and local behavior of a\ntwo-dimensional granular pillar, acting as a proxy for a disordered solid,\nunder uniaxial compression. This geometry allows for direct measurement of\nglobal material response, as well as tracking of all individual particle\ntrajectories. In general, drawing connections between local structure and local\ndynamics can be challenging in amorphous materials due to lower precision of\natomic positions, so this study aims to elucidate such connections. We vary\nlocal interactions by using three different particle shapes: discrete circular\ngrains (monomers), pairs of grains bonded together (dimers), and groups of\nthree bonded in a triangle (trimers). We find that dimers substantially\nstrengthen the pillar and the degree of this effect is determined by\norientational order in the initial condition. In addition, while the three\nparticle shapes form void regions at distinct rates, we find that anisotropies\nin the local amorphous structure remain robust through the definition of a\nmetric that quantifies packing anisotropy. Finally, we highlight connections\nbetween local deformation rates and local structure.",
        "positive": "Shear-induced overaging in a polymer glass: A phenomenon recently coined as ``overaging'' implies a slowdown in the\ncollective (slow) relaxation modes of a glass when a transient shear strain is\nimposed. We are able to reproduce this behavior in simulations of a supercooled\npolymer melt by imposing instantaneous shear deformations. The increases in\nrelaxation times $\\Delta \\tau_{1/2}$ rise rapidly with deformation, becoming\nexponential in the plastic regime. This ``overaging'' is distinct from standard\naging. We find increases in pressure, bond-orientational order and in the\naverage energy of the inherent structures ($<e_{IS}>$) of the system, all\ndependent on the size of the deformation. The observed change in behavior from\nelastic to plastic deformation suggests a link to the physics of the ``jammed\nstate''"
    },
    {
        "anchor": "Diffusive Dynamics of Water inside Hydrophobic Carbon Micropores Studied\n  by Neutron Spectroscopy and Molecular Dynamics Simulation: When water molecules are confined to nanoscale spacings, such as in the\nnanometer size pores of activated carbon fiber (ACF), their freezing point gets\nsuppressed down to very low temperatures ($\\sim$ 150 K), leading to a\nmetastable liquid state with remarkable physical properties. We have\ninvestigated the ambient pressure diffusive dynamics of water in microporous\nKynol\\texttrademark ACF-10 (average pore size $\\sim$11.6 {\\AA}, with primarily\nslit-like pores) from temperature $T=$ 280 K in its stable liquid state down to\n$T=$ 230 K into the metastable supercooled phase. The observed characteristic\nrelaxation times and diffusion coefficients are found to be respectively higher\nand lower than those in bulk water, indicating a slowing down of the water\nmobility with decreasing temperature. The observed temperature-dependent\naverage relaxation time $<\\tau>$ when compared to previous findings indicate\nthat it is the size of the confining pores - not their shape - that primarily\naffects the dynamics of water for pore sizes larger than 10 {\\AA}. The\nexperimental observations are compared to complementary molecular dynamics\nsimulations of a model system, in which we studied the diffusion of water\nwithin the 11.6 {\\AA} gap of two parallel graphene sheets. We find generally a\nreasonable agreement between the observed and calculated relaxation times at\nthe low momentum transfer $Q$ ($Q\\le 0.9$ \\AA${^{-1}}$). At high $Q$ however,\nwhere localized dynamics becomes relevant, this ideal system does not\nsatisfactorily reproduce the measurements. The best agreement is obtained for\nthe diffusion parameter $D$ associated with the hydrogen-site when a\nrepresentative stretched exponential function, rather than the standard\nbi-modal exponential model, is used to parameterize the self-correlation\nfunction $I(Q,t)$.",
        "positive": "The plane stress state of residually stressed bodies: a stress function\n  approach: The stressed state of flattened thin elastic sheet, as well as that of\ntranslationally symmetric 3D solids, are effectively 2D problems. This paper\nstudy equilibrium state-of-stress in metrically-incompatible 2D elastic\nmaterials. The solution is represented by a scalar stress function,\ngeneralizing the Airy stress function, which is determined by geometric\ncompatibility conditions. We develop a perturbative approximation method for\nsolving this stress function, valid for any constitutive relation. We apply the\nmethod for the case of a Hookean solid to solve prototypical examples in which\nthe classical Airy approach is either inaccurate or inapplicable. Results are\nshown to agree well with numerical results obtained in previous works."
    },
    {
        "anchor": "Initiation of fluid-induced fracture in a thick-walled hollow permeable\n  sphere: The initiation of fluid-induced fracture in formations of permeable\ngeomaterials subjected to quasi-stationary flow processes (drained response)\ncan be strongly affected by Biot's coefficient and the size of the formation.\nThe aim of this paper is to analyse the influence of these parameters on the\ninitial fracture process of a thick-walled hollow permeable sphere subjected to\nfluid injection in the hole. Assuming that fracture patterns are distributed\nuniformly during the hardening stage of the fracture initiation process, the\ncoupled fluid-solid problem is described by a nonlinear ordinary differential\nequation, which is solved numerically by means of finite differences combined\nwith shooting and Newton methods. The finite difference code has also been\nvalidated in the elastic range, i.e., before initiation of fracture, against an\noriginal closed-form analytical solution of the above differential equation.\nThe results show that the nominal strength of the sphere increases with\nincreasing Biot's coefficient and decreases with increasing size.",
        "positive": "Phase transitions of non-Abelian charged nodal links in a spring-mass\n  system: Although a large class of topological materials have uniformly been\nidentified using symmetry properties of wave functions, the past two years have\nseen the rise of multi-gap topologies beyond this paradigm. Given recent\nreports of unexplored features of such phases, platforms that are readily\nimplementable to realize them are therefore desirable. Here, we demonstrate\nthat multi-gap topological phase transitions of non-Abelian charged nodal lines\narise in classical phonon waves. By adopting a simple spring-mass system, we\nconstruct nodal lines of a three-band system. The braiding process of the nodal\nlines is readily performed by adjusting the spring constants. The generation\nand annihilation of the nodal lines are then analyzed using Euler class.\nFinally, we retrieve topological transitions from trivial nodal lines to a\nnodal link. Our work provides a simple platform that can offer diverse insights\nto not only theoretical but also experimental studies on multi-gap topology."
    },
    {
        "anchor": "Geometrical guidance and trapping transition of human sperm cells: The guidance of human sperm cells under confinement in quasi 2D microchambers\nis investigated using a purely physical method to control their distribution.\nTransport property measurements and simulations are performed with dilute sperm\npopulations, for which effects of geometrical guidance and concentration are\nstudied in detail. In particular, a trapping transition at convex angular wall\nfeatures is identified and analyzed. We also show that highly efficient\nmicroratchets can be fabricated by using curved asymmetric obstacles to take\nadvantage of the spermatozoa specific swimming strategy.",
        "positive": "Buckling dynamics of a solvent-stimulated stretched elastomeric sheet: When stretched uniaxially, a thin elastic sheet may exhibit buckling. The\noccurrence of buckling depends on the geometrical properties of the sheet and\nthe magnitude of the applied strain. Here we show that an elastomeric sheet\ninitially stable under uniaxial stretching can destabilize when exposed to a\nsolvent that swells the elastomer. We demonstrate experimentally and\ncomputationally that the features of the buckling pattern depend on the\nmagnitude of stretching, and this observation offers a new way for controlling\nthe shape of a swollen homogeneous thin sheet."
    },
    {
        "anchor": "Stability and collapse of a hybrid Bose-Einstein condensate of atoms and\n  molecules: The dynamics of stability and collapse of a trapped atomic Bose-Einstein\ncondensate (BEC) coupled to a molecular one is studied using the time-dependent\nGross-Pitaevskii (GP) equation including a nonlinear interaction term which can\ntransform two atoms into a molecule and vice versa. We find interesting\noscillation of the number of atoms and molecules for a BEC of fixed mass. This\noscillation is a consequence of continuous transformation in the condensate of\ntwo atoms into a molecule and vice versa. For the study of collapse an\nabsorptive contact interaction and an imaginary quartic three-body\nrecombination term are included in the GP equation. It is possible to have a\ncollapse of one or both components when one or more of the nonlinear terms in\nthe GP equation are attractive in nature, respectively.",
        "positive": "Flexible hydrogels connecting adhesion and wetting: Raindrops falling on window panes spread upon contact, whereas hail can cause\ndents or scratches on the same glass window upon contact. While the former\nphenomenon resembles classical wetting, the latter is dictated by contact and\nadhesion theories. The classical Young-Dupre law applies to the wetting of pure\nliquids on rigid solids, whereas conventional contact mechanics theories\naccount for rigid-on-soft or soft-on-rigid contacts with small deformations in\nthe elastic limit. However, the crossover between adhesion and wetting is yet\nto be fully resolved. The key lies in the study of soft-on-soft interactions\nwith material properties intermediate between liquids and solids. In this work,\nwe translate from adhesion to wetting by experimentally probing the static\nsignature of hydrogels in contact with soft PDMS of varying elasticity of both\nthe components. Consequently, we probe this transition across six orders of\nmagnitude in terms of the characteristic elasto-adhesive parameter of the\nsystem. In doing so, we reveal previously unknown phenomenology and a\ntheoretical model which smoothly bridges adhesion of glass spheres with total\nwetting of pure liquids on any given substrate. Lastly, we highlight how solid\nlike hydrogels can be treated as potential candidates for cleaning impurities\nfrom conventionally sticky PDMS substrates."
    },
    {
        "anchor": "\"Soft\" Anharmonic Vortex Glass in Ferromagnetic Superconductors: Ferromagnetic order in superconductors can induce a {\\em spontaneous} vortex\n(SV) state. For external field ${\\bf H}=0$, rotational symmetry guarantees a\nvanishing tilt modulus of the SV solid, leading to drastically different\nbehavior than that of a conventional, external-field-induced vortex solid. We\nshow that quenched disorder and anharmonic effects lead to elastic moduli that\nare wavevector-dependent out to arbitrarily long length scales, and non-Hookean\nelasticity. The latter implies that for weak external fields $H$, the magnetic\ninduction scales {\\em universally} like $B(H)\\sim B(0)+ c H^{\\alpha}$, with\n$\\alpha\\approx 0.72$. For weak disorder, we predict the SV solid is a\ntopologically ordered vortex glass, in the ``columnar elastic glass''\nuniversality class.",
        "positive": "Oblique helicoidal state of the twist-bend nematic doped by chiral\n  azo-compound: A novel light-sensitive chiral dopant ChD-3816 (an azo compound containing\n4-hexanoyloxyphenyl and 2-isopropyl-5-methylcyclohexylbenzoate moieties) was\nused for inducing helical twisting in Ntb-forming mixtures of CB7CB/CB6OCB with\n5CB added to decrease the phase transition temperatures. The effects of\nChD-3816 upon phase transition temperatures, as well as effects of its\nconcentration on the measured values of helical twisting were determined. Most\nof the measured parameters could be varied due to light-induced trans-cis\nisomerization of ChD-3816. Under electric field, selective reflection spectra\nin the visible range were obtained for the emerging ChOH structures, with the\nwavelengths controllable both by electric field and appropriate UV irradiation.\nPossible applications for dynamic formation of contrast images are discussed."
    },
    {
        "anchor": "Pressure Raman effects and internal stress in network glasses: Raman scattering from binary GexSe1-x glasses under hydrostatic pressure\nshows onset of a steady increase in the frequency of modes of corner-sharing\nGeSe4 tetrahedral units when the external pressure P exceeds a threshold value\nPc. The threshold pressure Pc(x) decreases with x in the 0.15 < x < 0.20 range,\nnearly vanishes in the 0.20 < x < 0.25 range, and then increases in the 0.25 <\nx < 1/3 range. These Pc(x) trends closely track those in the non-reversing\nenthalpy, DHnr(x), near glass transitions (Tgs), and in particular, both\nDHnr(x) and Pc(x) vanish in the reversibility window (0.20 < x < 0.25). It is\nsuggested that Pc provides a measure of stress at the Raman active units; and\nits vanishing in the reversibility window suggests that these units are part of\nan isostatically rigid backbone. Isostaticity also accounts for the non-aging\nbehavior of glasses observed in the reversibility window.",
        "positive": "Phase diagram and critical properties of Yukawa bilayers: We study the ground-state Wigner bilayers of pointlike particles with Yukawa\npairwise interactions, confined to the surface of two parallel hard walls at\ndimensionless distance $\\eta$. The model involves as limiting cases the\nunscreened Coulomb potential and hard spheres. The phase diagram of Yukawa\nparticles, studied numerically by Messina and L\\\"owen [Phys. Rev. Lett. 91\n(2003) 146101], exhibits five different staggered phases as $\\eta$ varies from\n0 to intermediate values. We present a lattice summation method using the\ngeneralized Misra functions which permits us to calculate the energy per\nparticle of the phases with a precision much higher than usual in computer\nsimulations. This allows us to address some tiny details of the phase diagram.\nGoing from the hexagonal phase I to phase II is shown to occur at $\\eta=0$,\nwhich resolves a longtime controversy. We find a tricritical point where\nMessina and L\\\"owen suggested a coexistence domain of several phases which was\nsuggested to divide the staggered rhombic phase into two separate regions. Our\ncalculations reveal one continuous region for this rhombic phase with a very\nnarrow connecting channel. Further we show that all second-order phase\ntransitions are of mean-field type. We also derive the asymptotic shape of\ncritical lines close to the Coulomb and hard-spheres limits. In and close to\nthe hard-spheres limit, the dependence of the internal parameters of the\npresent phases on $\\eta$ is determined exactly."
    },
    {
        "anchor": "Nonlinear elastic stress response in granular packings: We study the nonlinear elastic response of a two-dimensional material to a\nlocalized boundary force, with the particular goal of understanding the\ndifferences observed between isotropic granular materials and those with\nhexagonal anisotropy. Corrections to the classical Boussinesq result for the\nstresses in an infinite half-space of a linear, isotropic material are\ndeveloped in a power series in inverse distance from the point of application\nof the force. The breakdown of continuum theory on scales of order of the grain\nsize is modeled with phenomenological parameters characterizing the strengths\nof induced multipoles near the point of application of the external force. We\nfind that the data of Geng et al. on isotropic and hexagonal packings of\nphotoelastic grains can be fit within this framework. Fitting the hexagonal\npackings requires a choice of elastic coefficients with hexagonal anisotropy\nstronger than that of a simple ball and spring model. For both the isotropic\nand hexagonal cases, induced dipole and quadrupole terms produce propagation of\nstresses away from the vertical direction over short distances. The scale over\nwhich such propagation occurs is significantly enhanced by the nonlinearities\nthat generate hexagonal anisotropy.",
        "positive": "Band Formation during Gaseous Diffusion in Aerogels: We study experimentally how gaseous HCl and NH_3 diffuse from opposite sides\nof and react in silica aerogel rods with porosity of 92 % and average pore size\nof about 50 nm. The reaction leads to solid NH_4Cl, which is deposited in thin\nsheet-like structures. We present a numerical study of the phenomenon. Due to\nthe difference in boundary conditions between this system and those usually\nstudied, we find the sheet-like structures in the aerogel to differ\nsignificantly from older studies. The influence of random nucleation centers\nand inhomogeneities in the aerogel is studied numerically."
    },
    {
        "anchor": "Mechanics and energetics of electromembranes: The recent discovery of electro-active polymers has shown great promises in\nthe field of soft robotics, and was logically followed by experimental,\nnumerical and theoretical developments. Most of these studies were concerned\nwith systems entirely covered by electrodes. However, there is a growing\ninterest for partially active polymers, in which the electrode covers only one\npart of the membrane. Indeed, such actuation can trigger buckling instabilities\nand so represents a route toward the control of 3D shapes. Here, we study\ntheoretically the behaviour of such partially active electro-active polymer. We\naddress two problems: (i) the electrostatic elastica including geometric\nnon-linearities and partially electro-active strip using a variational\napproach. We propose a new interpretation of the equations of deformation, by\ndrawing analogies with biological growth, in which the effect of the electric\nvoltage is seen as a change in the reference stress-free state. (ii) we explain\nthe nature of the distribution of electrostatic forces on this simple system,\nwhich is not trivial. In particular we find that edge effects are playing a\nmajor role in this problem.",
        "positive": "Modelling of thermosensitive stereoregular polymers within MARTINI\n  coarse-grained force-field: poly(N-isopropylacrylamide) as a benchmark case: In this article we introduce the MARTINI model of a widely used\nthermoresponsive polymer, Poly(N-isopropylacrylamide). Importantly, our model\ntakes into account polymer's stereoregularity (i.e. tacticity). We highlight\nthe effect of changing the polarity of coarse-grained particles comprising the\npolymer on its ability to exhibit a temperature-dependent coil-to-globule\ntransition. Our approach allows to study the behavior of thermoresponsive\npolymers at large time and length scales."
    },
    {
        "anchor": "Sedimentation stacking diagram of binary colloidal mixtures and bulk\n  phases in the plane of chemical potentials: We give a full account of a recently proposed theory that explicitly relates\nthe bulk phase diagram of a binary colloidal mixture to its phase stacking\nphenomenology under gravity [Soft Matter 9, 8636 (2013)]. As we demonstrate,\nthe full set of possible phase stacking sequences in sedimentation-diffusion\nequilibrium originates from straight lines (sedimentation paths) in the\nchemical potential representation of the bulk phase diagram. From the analysis\nof various standard topologies of bulk phase diagrams, we conclude that the\ncorresponding sedimentation stacking diagrams can be very rich, even more so\nwhen finite sample height is taken into account. We apply the theory to obtain\nthe stacking diagram of a mixture of nonadsorbing polymers and colloids. We\nalso present a catalog of generic phase diagrams in the plane of chemical\npotentials in order to facilitate the practical application of our concept,\nwhich also generalizes to multi component mixtures.",
        "positive": "Toughening elastomers via microstructured thermoplastic fibers with\n  sacrificial bonds and hidden lengths: Soft materials capable of large inelastic deformation play an essential role\nin high-performance nacre-inspired architectured materials with a combination\nof stiffness, strength and toughness. The rigid \"building blocks\" made from\nglass or ceramic in these architectured materials lack inelastic deformation\ncapabilities and thus rely on the soft interface material that bonds together\nthese building blocks to achieve large deformation and high toughness. Here, we\ndemonstrate the concept of achieving large inelastic deformation and high\nenergy dissipation in soft materials by embedding microstructured thermoplastic\nfibers with sacrificial bonds and hidden lengths in a widely used elastomer.\nThe microstructured fibers are fabricated by harnessing the fluid-mechanical\ninstability of a molten polycarbonate (PC) thread on a commercial 3D printer.\nPolydimethylsiloxane (PDMS) resin is infiltrated around the fibers, creating a\nsoft composite after curing. The failure mechanism and damage tolerance of the\ncomposite are analyzed through fracture tests. The high energy dissipation is\nfound to be related to the multiple fracture events of both the sacrificial\nbonds and elastomer matrix. Combining the microstructured fibers and straight\nfibers in the elastomer composite results in a ~ 17 times increase in stiffness\nand a ~ 7 times increase in total energy to failure compared to the neat\nelastomer. Our findings in applying the sacrificial bonds and hidden lengths\ntoughening mechanism in soft materials at the microscopic scale will facilitate\nthe development of novel bioinspired laminated composite materials with high\nmechanical performance."
    },
    {
        "anchor": "Cooperative melting in double-stranded peptide chains through local\n  mechanical interactions: Under an external field a double-stranded peptide chain can separate in a\nfragile or ductile transition. It is usually believed that these two regimes\nare driven either by chemical and thermal fields, or through non-local\nmechanical interactions. Here, we show explicitly that local mechanical\ninteractions regulates the stability and reversibility of the\ncooperative/non-cooperative melting transition, which is described by a single\nparameter depending on an internal length scale. Our theory is applicable to a\nwide range of biological examples such as DNA, protein secondary structures,\nand the microtubules and tau proteins, for which we are able to predict the\ncritical melting force as a function of the chain length.",
        "positive": "Dynamics of Protein Hydration Water: We present the frequency- and temperature-dependent dielectric properties of\nlysozyme solutions in a broad concentration regime, measured at subzero\ntemperatures and compare the results with measurements above the freezing point\nof water and on hydrated lysozyme powder. Our experiments allow examining the\ndynamics of unfreezable hydration water in a broad temperature range including\nthe so-called No Man's Land (160 - 235 K). The obtained results prove the\nbimodality of the hydration shell dynamics and are discussed in the context of\nthe highly-debated fragile-to-strong transition of water."
    },
    {
        "anchor": "Highly Confined Stacks of Graphene Oxide Sheets in Water: Since the discovery of graphene oxide (GO), the most accessible of the\nprecursors of graphene, this material has been widely studied for applications\nin science and technology. In this work, we describe a procedure to obtain GO\ndispersions in water at high concentrations, these highly dehydrated\ndispersions being in addition fully redispersible by dilution. With the\navailability of such concentrated samples, it was possible to investigate the\nstructure of hydrated GO sheets in a previously unexplored range of\nconcentrations, and to evidence a structural phase transition. Tentatively\napplying models designed for describing the small-angle scattering curve in the\nSmectic A (or L$_{\\alpha}$) phase of lyotropic systems, it was possible to\nextract elastic parameters characterising the system on the dilute side of the\ntransition, thereby evidencing the relevance of both electrostatic and steric\n(Helfrich) interactions in stabilising aqueous lamellar stacks of GO sheets",
        "positive": "Computer simulations of the restricted primitive model at very low\n  temperature and density: The problem of successfully simulating ionic fluids at low temperature and\nlow density states is well known in the simulation literature: using\nconventional methods, the system is not able to equilibrate rapidly due to the\npresence of strongly associated cation-anion pairs. In this manuscript we\npresent a numerical method for speeding up computer simulations of the\nrestricted primitive model (RPM) at low temperatures (around the critical\ntemperature) and at very low densities (down to $10^{-10}\\sigma^{-3}$, where\n$\\sigma$ is the ion diameter). Experimentally, this regime corresponds to\ntypical concentrations of electrolytes in nonaqueous solvents. As far as we are\naware, this is the first time that the RPM has been equilibrated at such\nextremely low concentrations. More generally, this method could be used to\nequilibrate other systems that form aggregates at low concentrations."
    },
    {
        "anchor": "Capillary rupture of suspended polymer concentric rings: We present the first experimental study on the simultaneous capillary\ninstability amongst viscous concentric rings suspended atop an immiscible\nmedium. The rings ruptured upon annealing, with three types of phase\ncorrelation between neighboring rings. In the case of weak substrate\nconfinement, the rings ruptured independently when they were sparsely\ndistanced, but via an out-of-phase mode when packed closer. If the substrate\nconfinement was strong, the rings would rupture via an in-phase mode, resulting\nin radially aligned droplets. The concentric ring geometry caused a competition\nbetween the phase correlation of neighboring rings and the kinetically\nfavorable wavelength, yielding an intriguing, recursive surface pattern. This\nfrustrated pattern formation behavior was accounted for by a scaling analysis.",
        "positive": "Driving rate dependence of avalanche statistics and shapes at the\n  yielding transition: We study stress time series caused by plastic avalanches in athermally\nsheared disordered materials. Using particle-based simulations and a mesoscopic\nelasto-plastic model, we analyze size and shear-rate dependence of the\nstress-drop durations and size distributions together with their average\ntemporal shape. We find critical exponents different from mean-field\npredictions, and a clear asymmetry for individual avalanches. We probe scaling\nrelations for the rate dependency of the dynamics and we report a crossover\ntowards mean-field results for strong driving."
    },
    {
        "anchor": "Peak Effect and Dynamics of Stripe and Pattern Forming Systems on a\n  Periodic One Dimensional Substrate: We examine the ordering, pinning, and dynamics of two-dimensional pattern\nforming systems interacting with a periodic one-dimensional substrate. In the\nabsence of the substrate, particles with competing long-range repulsion and\nshort-range attraction form anisotropic crystal, stripe, and bubble states.\nWhen the system is tuned across the stripe transition in the presence of a\nsubstrate, we find that there is a peak effect in the critical depinning force\nwhen the stripes align and become commensurate with the substrate. Under an\napplied drive, the anisotropic crystal and stripe states can exhibit soliton\ndepinning and plastic flow. When the stripes depin plastically, they\ndynamically reorder into a moving stripe state that is perpendicular to the\nsubstrate trough direction. We also find that when the substrate spacing is\nsmaller than the widths of the bubbles or stripes, the system forms pinned\nstripe states that are perpendicular to the substrate trough direction. The\nsystem exhibits multiple reentrant pinning effects as a function of increasing\nattraction, with the anisotropic crystal and large bubble states experiencing\nweak pinning but the stripe and smaller bubble states showing stronger pinning.\nWe map out the different dynamic phases as a function of filling, the strength\nof the attractive interaction term, the substrate strength, and the drive, and\ndemonstrate that the different phases produce identifiable features in the\ntransport curves and particle orderings.",
        "positive": "Driven active matter: fluctuations and a hydrodynamic instability: Wet active matter in the presence of an imposed temperature gradient, or\nchemical potential gradient, is considered. It is shown that there is a new\ntype of convective instability that is caused by a (negative) activity\nparameter. Physically this corresponds to active fluids with contractual\nstress. In this non-equilibrium steady state the singular generic long-ranged\ncorrelations are computed and compared with the analogous results in a passive\nfluid. In addition, the singular non-equlibirum Casimir pressure or force is\ndetermined. The fluid motion above the instability is determined by\ngeneralizing the Lorenz equations for the Rayleigh-Benard instability in a\npassive fluid to Lorenz-like equations to describe this new instability."
    },
    {
        "anchor": "Translocation energy of ions in nano-channels of cell membranes: Translocation properties of ionic channels are investigated, on the basis of\nclassical electrostatics, with an emphasis on asymptotic formulas for the\npotential and field associated with a point charge in the channel. Due to image\ncharges in the membrane, we show that ions in an infinite length channel\ninteract via a one-dimensional (1D) Coulomb potential. The corresponding\nelectrostatic barrier $\\Sigma$ is characterized by a \"geometric mean\" screening\n$\\Sigma \\propto e^2 / \\sqrt{\\epsilon_w \\epsilon_m}R$ ($R$ being the radius of\nthe pore, and $\\epsilon_m \\approx 2$ and $\\epsilon_w \\approx 80$ the room\ntemperature dielectric constants of membrane and water, respectively). There\nexists a crossover length, $x_0 \\propto R \\sqrt{\\epsilon_w / \\epsilon_m} \\sim\n6.3 R$, below which the 1D potential governs the electrostatics and beyond\nwhich the three-dimensional (3D) Coulomb potential screened by the membrane\ntakes over. Knowledge of this length enables us to discriminate between long\nchannels, the length $L$ of which satisfies: $L \\gg 2 x_0$, and short channels\nfor which $L \\ll 2 x_0$. The latter condition is satisfied by most realistic\nchannels ({\\it e.g.}, gramicidin A where $R \\approx 3 {\\mathrm{\\AA}}$, $L\n\\approx 2.5 {\\mathrm{nm}}$ and $2x_0 \\approx 3.8 {\\mathrm{nm}}$) whose\ntranslocation energy is therefore controlled by the part of the self-energy,\n$\\Sigma$, arising from the 1D potential. On this basis, we derive an expression\nfor $\\Sigma$, with no fitting parameter, which applies to a generic\nnano-channel of length $L$ and radius $R$.",
        "positive": "Scattering of signal in vertical granular chain with impurities: We investigate the scattering process of impulse from impurities in vertical\ngranular chain system under gravity. Most of the studies are focused on the\ncase of light impurities. The reflection rates follow power laws with the\nimpuity depth. There is a valley in the curve of reflection rate versus the\ninitial perturbation strength and the curve is not symmetric. Some results on\nthe scattering process from heavy impurities are also presented. There is a\ntransition region in the initial velocity space. Through this region the\nexponent for leading peak changes smoothly from its saturant value in small $\nv_i$ side to its saturant value in large $v_i$ side; the exponent for signal\nspeed changes smoothly from its saturant value in small $v_i$ side to its\nsaturant value in large $v_i$ side. Both the peak of the exponent for\nreflection rate and the valley for the reflection rate versus $v_i$ also locate\nwithin this transition region."
    },
    {
        "anchor": "Finite-size excess-entropy scaling for simple liquids: We introduce and validate a finite-size two-body excess entropy integral\nequation. By using analytical arguments and computer simulations of\nprototypical simple liquids, we show that the excess entropy $s_2$ exhibits a\nfinite-size scaling with the inverse of the linear size of the simulation box.\nSince the self-diffusivity coefficient $D^*$ displays a similar finite-size\neffect, we show that the scaling entropy relation $D^*=A\\exp(\\alpha s_2)$ also\ndepends on the simulation box size. By extrapolating to the thermodynamic\nlimit, we report values for the coefficients $A$ and $\\alpha$ that agree well\nwith values available in the literature. Finally, we find a power law relation\nbetween the scaling coefficients for $D^*$ and $s_2$, suggesting a constant\nviscosity to entropy ratio.",
        "positive": "Dynamic Equivalence between Soft Star Polymers and Hard Spheres: Understanding the dynamics of soft colloids, such as star polymers,\ndendrimers, and microgels, is of scientific and practical importance. It is\nknown that the excluded volume effect plays a key role in colloidal dynamics.\nHere, we propose a condition of compressibility equivalence that provides a\nsimple method to experimentally evaluate the excluded volume of soft colloids\nfrom a thermodynamic view. We apply this condition to survey the dynamics of a\nseries of star polymer dispersions. It is found that as the concentration\nincreases, the slowing of the long-time self-diffusivity of the star polymer,\nnormalized by the short-time self-diffusivity, can be mapped onto the\nhard-sphere behavior. This phenomenon reveals the dynamic equivalence between\nsoft colloids and hard spheres, despite the apparent complexity of the\ninterparticle interaction of the soft colloids. The methods for measuring the\nosmotic compressibility and the self-diffusivities of soft colloidal\ndispersions are also presented."
    },
    {
        "anchor": "Correlation functions in liquids and crystals : Free energy functional\n  and liquid - crystal transition: A free energy functional for a crystal that contains both the symmetry\nconserved and symmetry broken parts of the direct pair correlation function has\nbeen used to investigate the crystallization of fluids in three-dimensions. The\nsymmetry broken part of the direct pair correlation function has been\ncalculated using a series in ascending powers of the order parameters and which\ncontains three- and higher-bodies direct correlation functions of the isotropic\nphase. It is shown that a very accurate description of freezing transitions for\na wide class of potentials is found by considering the first two terms of this\nseries. The results found for freezing parameters including structure of the\nfrozen phase for fluids interacting via the inverse power potential u(r) =\n\\epsilon (\\sigma/r)^{n} for n ranging from 4 to \\infty are in very good\nagreement with simulation results. It is found that for n > 6.5 the fluid\nfreezes into a face centred cubic (fcc) structure while for n \\leq 6 the body\ncentred cubic (bcc) structure is preferred. The fluid-bcc-fcc triple point is\nfound to be at 1/n = 0.158 which is in good agreement with simulation result.",
        "positive": "A sheet-like structure in the proximity of compact DNA: We determine the phase diagram of DNA with inter- and intra-strand\nnative-pair interactions that mimic the compaction of DNA. We show that DNA\ntakes an overall sheet-like structure in the region where an incipient\ntransition to a compact phase would have occurred. The stability of this phase\nis due to the extra entropy from the folding of the sheet, which is absent in\nthe remaining polymer-like states of the phase diagram."
    },
    {
        "anchor": "Activity-induced asymmetric dispersion in confined channels with\n  constriction: Microorganisms, such as E.Coli, are known to display upstream behavior and\nrespond rheotactically to shear flows. In particular, E.Coli suspensions have\nbeen shown to display strong sensitivity to spatial constrictions, leading to\nan anomalous densification past the constriction for incoming fluid velocities\ncomparable to the microoganism's self propulsion speed. We introduce a Brownian\ndynamics model for ellipsoidal self-propelling particles in a confined channel\nsubject to a constriction. The model allows to identify the relevant parameters\nthat characterize the relevant dynamical regimes of the accumulation of the\nactive particles at the constriction, and clarify the mechanisms underlying the\nexperimental observations. We find that particles are trapped in butterfly-like\nattractors in front of the constriction, which is the origin of the symmetry\nbreaking in the emerging density profiles of active particles passing the\nconstriction. In addition, the probability of trapping and thus the strength of\nasymmetry is affected by size of the particles and geometry of the channel, as\nwell as the ratio of fluid velocity to propulsion speed.",
        "positive": "The Anatomy of Plastic Events in Magnetic Amorphous Solids: Plastic events in amorphous solids can be much more than just \"shear\ntransformation zones\" when the positional degrees of freedom are coupled\nnon-trivially to other degrees of freedom. Here we consider magnetic amorphous\nsolids where mechanical and magnetic degrees of freedom interact, leading to\nrather complex plastic events whose nature must be disentangled. In this paper\nwe uncover the anatomy of the various contributions to some typical plastic\nevents. These plastic events are seen as Barkhausen Noise or other \"serrated\nnoises\". Using theoretical considerations we explain the observed statistics of\nthe various contributions to the considered plastic events. The richness of\ncontributions and their different characteristics imply that in general the\nstatistics of these \"serrated noises\" cannot be universal, but rather highly\ndependent on the state of the system and on its microscopic interactions."
    },
    {
        "anchor": "Simple shear flow in inelastic Maxwell models: The Boltzmann equation for inelastic Maxwell models is considered to\ndetermine the velocity moments through fourth degree in the simple shear flow\nstate. First, the rheological properties (which are related to the\nsecond-degree velocity moments) are {\\em exactly} evaluated in terms of the\ncoefficient of restitution $\\alpha$ and the (reduced) shear rate $a^*$. For a\ngiven value of $\\alpha$, the above transport properties decrease with\nincreasing shear rate. Moreover, as expected, the third-degree and the\nasymmetric fourth-degree moments vanish in the long time limit when they are\nscaled with the thermal speed. On the other hand, as in the case of elastic\ncollisions, our results show that, for a given value of $\\alpha$, the scaled\nsymmetric fourth-degree moments diverge in time for shear rates larger than a\ncertain critical value $a_c^*(\\alpha)$ which decreases with increasing\ndissipation. The explicit shear-rate dependence of the fourth-degree moments\nbelow this critical value is also obtained.",
        "positive": "The Role of Solid Friction in the Sedimentation of Strongly Attractive\n  Colloidal Gels: We study experimentally and theoretically the sedimentation of gels made of\nstrongly aggregated colloidal particles, focussing on the long time behavior,\nwhen mechanical equilibrium is asymptotically reached. The asymptotic gel\nheight is found to vary linearly with the initial height, a finding in stark\ncontrast with a recent study on similar gels [Manley \\textit{et al.} 2005\n\\textit{Phys. Rev. Lett.} \\textbf{94} 218302]. We show that the asymptotic\ncompaction results from the balance between gravity pull, network elasticity,\nand solid friction between the gel and the container walls. Based on these\ningredients, we propose a simple model to account for the dependence of the\nheight loss on the initial height and volume fraction. As a result of our\nanalysis, we show that the static friction coefficient between the gel and the\ncontainer walls strongly depends on volume fraction: the higher the volume\nfraction, the weaker the solid friction. This nonintuitive behavior is\nexplained using simple scaling arguments."
    },
    {
        "anchor": "Granular Structure Determined by Terahertz Scattering: Light-scattering in the terahertz region is demonstrated for granular matter.\nA quantum-cascade laser is used in a benchtop setup to determine the\nangle-dependent scattering of spherical grains as well as coffee powder and\nsugar grains. For the interpretation of the form factors for the scattering\nfrom single particles one has to go beyond the usual Rayleigh-Gans-Debye theory\nand apply calculations within Mie theory. In addition to single scattering also\ncollective correlations can be identified and extracted as a static structure\nfactor.",
        "positive": "Manifestation of nonequilibrium initial conditions in molecular\n  rotation: the generalized J-diffusion model: In order to adequately describe molecular rotation far from equilibrium, we\nhave generalized the J-diffusion model by allowing the rotational relaxation\nrate to be angular momentum dependent. The calculated nonequilibrium rotational\ncorrelation functions (CFs) are shown to decay much slower than their\nequilibrium counterparts, and orientational CFs of hot molecules exhibit\ncoherent behavior, which persists for several rotational periods. As distinct\nfrom the results of standard theories, rotational and orientational CFs are\nfound to dependent strongly on the nonequilibrium preparation of the molecular\nensemble. We predict the Arrhenius energy dependence of rotational relaxation\ntimes and violation of the Hubbard relations for orientational relaxation\ntimes. The standard and generalized J-diffusion models are shown to be almost\nindistinguishable under equilibrium conditions. Far from equilibrium, their\npredictions may differ dramatically."
    },
    {
        "anchor": "Stirring by Periodic Arrays of Microswimmers: The interaction between swimming microorganisms or artificial self-propelled\ncolloids and passive (tracer) particles in a fluid leads to enhanced diffusion\nof the tracers. This enhancement has attracted strong interest, as it could\nlead to new strategies to tackle the difficult problem of mixing on a\nmicrofluidic scale. Most of the theoretical work on this topic has focused on\nhydrodynamic interactions between the tracers and swimmers in a bulk fluid.\nHowever, in simulations, periodic boundary conditions (PBCs) are often imposed\non the sample and the fluid. Here, we theoretically analyze the effect of PBCs\non the hydrodynamic interactions between tracer particles and microswimmers. We\nformulate an Ewald sum for the leading-order stresslet singularity produced by\na swimmer to probe the effect of PBCs on tracer trajectories. We find that\nintroducing periodicity into the system has a surprisingly significant effect,\neven for relatively small swimmer-tracer separations. We also find that the\nbulk limit is only reached for very large system sizes, which are challenging\nto simulate with most hydrodynamic solvers.",
        "positive": "A scalable method to model large suspensions of colloidal phoretic\n  particles with arbitrary shapes: Phoretic colloids self-propel thanks to surface flows generated in response\nto surface gradients (thermal, electrical, or chemical), that are self-induced\nand/or generated by other particles. Here we present a scalable and versatile\nframework to model chemical and hydrodynamic interactions in large suspensions\nof arbitrarily shaped phoretic particles, accounting for thermal fluctuations\nat all Damkholer numbers. Our approach, inspired by the Boundary Element Method\n(BEM), employs second-layer formulations, regularised kernels and a grid\noptimisation strategy to solve the coupled Laplace-Stokes equations with\nreasonable accuracy at a fraction of the computational cost associated with\nBEM. As demonstrated by our large-scale simulations, the capabilities of our\nmethod enable the exploration of new physical phenomena that, to our knowledge,\nhave not been previously addressed by numerical simulations."
    },
    {
        "anchor": "How Close to Two Dimensions Does a Lennard-Jones System Need to Be to\n  Produce a Hexatic Phase?: We report on a computer simulation study of a Lennard-Jones liquid confined\nin a narrow slit pore with tunable attractive walls. In order to investigate\nhow freezing in this system occurs, we perform an analysis using different\norder parameters. Although some of the parameters indicate that the system goes\nthrough a hexatic phase, other parameters do not. This shows that to be certain\nwhether a system has a hexatic phase, one needs to study not only a large\nsystem, but also several order parameters to check all necessary properties. We\nfind that the Binder cumulant is the most reliable one to prove the existence\nof a hexatic phase. We observe an intermediate hexatic phase only in a\nmonolayer of particles confined such that the fluctuations in the positions\nperpendicular to the walls are less then 0.15 particle diameters, i. e. if the\nsystem is practically perfectly 2d.",
        "positive": "Twist and Measure: Characterizing the Effective Radius of Strings and\n  Bundles under Twisting Contraction: We test the standard model for the length contraction of a bundle of strings\nunder twist, and find deviation that is significantly greater than typically\nappreciated and that has a different nature at medium and large twist angles.\nBy including volume conservation, we achieve better fits to data for single-,\ndouble-, and triple-stranded bundles of Nylon monofilament as an ideal test\ncase. This gives a well-defined procedure for extracting an effective twist\nradius that characterizes contraction behavior. While our approach accounts for\nthe observed faster-than-expected contraction up to medium twist angles, we\nalso find that the contraction is nevertheless slower than expected at large\ntwist angles for both Nylon monofilament bundles and several other string\ntypes. The size of this effect varies with the individual-string braid\nstructure and with the number of strings in the bundle. We speculate that it\nmay be related to elastic deformation within the material. However, our first\nmodeling attempt does not fully capture the observed behavior."
    },
    {
        "anchor": "$\u03bc$-model for the statics of dry granular medium: We propose the description of the granular matter which is based on\ndistribution of dry friction coefficients. Using such a concept and a simple\none-dimensional packing of grains we solve the silo problem. The friction\ncoefficients at contacts are determined both by geometry of packing\nconfiguration and the stress distribution in a medium. Within such an approach\nthe Janssen coefficient is determined and its dependence on the\nparticle-particle and boundary-particle friction coefficients is obtained. Also\nwe investigate the conditions for the appearance of the maximum in the pressure\ndistribution with the depth with overweight on top. As an outcome of our work\nwe propose the general framework to the description of the granular matter as a\ncontinual medium which is characterized by the field of the dry friction\ntensor.",
        "positive": "A close look into the excluded volume effects within a double layer: We explore the effect of steric interaction on the ionic density distribution\nnear a charged hard wall. For weakly charged walls, small particles, and\nmonovalent ions the mean-field Poisson-Boltzmann equation provides an excellent\ndescription of the density profiles. For large ions and large surface charges,\nhowever, deviations appear. To explore these, we use the density functional\ntheory. We find that local density functionals are not able to account for\nsteric interactions near a wall. Based on the weighted density approximation we\nderive a simple analytical expression for the contact electrostatic potential\nwhich allows us to analytically calculate the differential capacitance of the\ndouble layer."
    },
    {
        "anchor": "Movers and shakers: Granular damping in microgravity: The response of an oscillating granular damper to an initial perturbation is\nstudied using experiments performed in microgravity and granular dynamics\nmulations. High-speed video and image processing techniques are used to extract\nexperimental data. An inelastic hard sphere model is developed to perform\nsimulations and the results are in excellent agreement with the experiments.\nThe granular damper behaves like a frictional damper and a linear decay of the\namplitude is bserved. This is true even for the simulation model, where\nfriction forces are absent. A simple expression is developed which predicts the\noptimal damping conditions for a given amplitude and is independent of the\noscillation frequency and particle inelasticities.",
        "positive": "Distinct aggregation patterns and fluid porous phase in a 2D model for\n  colloids with competitive interactions: In this paper we explore the self-assembly patterns in a two dimensional\ncolloidal system using extensive Langevin Dynamics simulations. The pair\npotential proposed to model the competitive interaction have a short range\nlength scale between first neighbors and a second characteristic length scale\nbetween third neighbors. We investigate how the temperature and colloidal\ndensity will affect the assembled morphologies. The potential shows aggregate\npatterns similar to observed in previous works, as clusters, stripes and porous\nphase. Nevertheless, we observe at high densities and temperatures a porous\nmesophase with a high mobility, which we name fluid porous phase, while at\nlower temperatures the porous structure is rigid. triangular packing was\nobserved for the colloids and pores in both solid and fluid porous phases. Our\nresults show that the porous structure is well defined for a large range of\ntemperature and density, and that the fluid porous phase is a consequence of\nthe competitive interaction and the random forces from the Langevin Dynamics."
    },
    {
        "anchor": "Random organization and non-equilibrium hyperuniform fluids on a sphere: Random organizing hyperuniform fluid induced by reciprocal activation is a\nnon-equilibrium fluid with vanishing density fluctuations at large length\nscales like crystals. Here we extend this new state of matter to a closed\nmanifold, namely a spherical surface. We find that the random organization on a\nspherical surface behaves similar to that in two dimensional Euclidean space,\nand the absorbing transition on a sphere also belongs to the conserved directed\npercolation universality class. Moreover, the reciprocal activation can also\ninduce a non-equilibrium hyperuniform fluid on a sphere. The spherical\nstructure factor at the absorbing transition and the non-equilibrium\nhyperuniform fluid phases are scaled as $S(l \\rightarrow 0) \\sim (l/R)^{0.45}$\nand $S(l \\rightarrow 0) \\sim l(l+1)/R^2$, respectively, which are both\nhyperuniform according to the definition of hyperuniformity on a sphere with\n$l$ the wave number and $R$ the radius of the spherical surface. We also\nconsider the impact of inertia in realistic hyperuniform fluids, and it is\nfound only adding an extra length-scale, above which hyperuniform scaling\nappears. Our finding suggests a new method for creating non-equilibrium\nhyperuniform fluids on closed manifolds to avoid boundary effects.",
        "positive": "Reversible self-assembly of patchy particles into monodisperse\n  icosahedral clusters: We systematically study the design of simple patchy sphere models that\nreversibly self-assemble into monodisperse icosahedral clusters. We find that\nthe optimal patch width is a compromise between structural specificity (the\npatches must be narrow enough to energetically select the desired clusters) and\nkinetic accessibility (they must be sufficiently wide to avoid kinetic traps).\nSimilarly, for good yields the temperature must be low enough for the clusters\nto be thermodynamically stable, but the clusters must also have enough thermal\nenergy to allow incorrectly formed bonds to be broken. Ordered clusters can\nform through a number of different dynamic pathways, including direct\nnucleation and indirect pathways involving large disordered intermediates. The\nlatter pathway is related to a reentrant liquid-to-gas transition that occurs\nfor intermediate patch widths upon lowering the temperature. We also find that\nthe assembly process is robust to inaccurate patch placement up to a certain\nthreshold, and that it is possible to replace the five discrete patches with a\nsingle ring patch with no significant loss in yield."
    },
    {
        "anchor": "Nematic Films and Radially Anisotropic Delaunay Surfaces: We develop a theory of axisymmetric surfaces minimizing a combination of\nsurface tension and nematic elastic energies which may be suitable for\ndescribing simple film and bubble shapes. As a function of the elastic constant\nand the applied tension on the bubbles, we find the analogues of the unduloid,\nsphere, and nodoid in addition to other new surfaces.",
        "positive": "Relaxation dynamics of glasses along a wide stability and temperature\n  range: While lot of measurements describe the relaxation dynamics of the liquid\nstate, experimental data of the glass dynamics at high temperatures are much\nscarcer. We use ultrafast scanning calorimetry to expand the timescales of the\nglass to much shorter values than previously achieved. Our data show that the\nrelaxation time of glasses follows a super-Arrhenius behaviour in the\nhigh-temperature regime above the conventional devitrification temperature\nheating at 10 K/min. The liquid and glass states can be described by a common\nVFT-like expression that solely depends on temperature and limiting fictive\ntemperature. We apply this common description to nearly-isotropic glasses of\nindomethacin, toluene and to recent data on metallic glasses. We also show that\nthe dynamics of indomethacin glasses obey density scaling laws originally\nderived for the liquid. This work provides a strong connection between the\ndynamics of the equilibrium supercooled liquid and non-equilibrium glassy\nstates."
    },
    {
        "anchor": "Limitations of atomistic modeling to reveal ejection of proteins from\n  charged nanodroplets: Molecular dynamics using atomistic modeling is frequently used to unravel the\nmechanisms of macroion release from electrosprayed droplets. However, atomistic\nmodeling is currently feasible for only the smallest window of droplet sizes\nappearing at the end of a disintegrating droplet's lifetime. The relevance of\nthe observations made to the actual droplet evolution, which is much longer\nthat the simulated sizes, has not been addressed. Here, we perform a systematic\nstudy of desolvation mechanisms of poly(ethylene glycol) (PEG), protonated\npeptides of different compositions and proteins in order to (a) examine whether\natomistic modeling can establish the extrusion mechanism of proteins from\ndroplets and (b) obtain insight for the charging mechanism in larger droplets\nthan those simulated. Atomistic modeling of PEG charging shows that above a\ncritical droplet size charging occurs transiently by transfer of ions from the\nsolvent to the macroion, while below the critical size, the capture of the ion\nfrom PEG has a lifetime sufficiently long for extrusion of the charged PEG from\nan aqueous droplet. This is the first report of the role of droplet curvature\nin the conformations and charging of macroions. Simulations with highly\nhydrophobic peptides show that partial extrusion of a peptide from the droplet\nsurface is rare relative to desolvation by drying-out. Differently from what\nhas been presented in the literature we argue that atomistic simulations have\nnot sufficiently established extrusion mechanism of proteins from droplets and\ntheir charging mechanism. Moreover, we argue that release of highly charged\nproteins can occur at an earlier stage of a droplet's lifetime than predicted\nby atomistic modeling. In this earlier stage, we emphasize the key role of jets\nemanating from a droplet at the point of charge-induced instability in the\nrelease of proteins.",
        "positive": "Overcurvature induced multistability of linked conical frusta: How a\n  `bendy straw' holds its shape: We study the origins of multiple mechanically stable states exhibited by an\nelastic shell comprising multiple conical frusta, a geometry common to\nreconfigurable corrugated structures such as `bendy straws'. This\nmultistability is characterized by mechanical stability of axially extended and\ncollapsed states, as well as a partially inverted `bent' state that exhibits\nstability in any azimuthal direction. To understand the origin of this\nbehavior, we study how geometry and internal stress affect the stability of\nlinked conical frusta. We find that tuning geometrical parameters such as the\nfrustum heights and cone angles can provide axial bistability, whereas\nstability in the bent state requires a sufficient amount of internal\npre-stress, resulting from a mismatch between the natural and geometric\ncurvatures of the shell. We analyze the latter effect through curvature\nanalysis during deformation using X-ray computed tomography (CT), and with a\nsimple mechanical model that captures the qualitative behavior of these highly\nreconfigurable systems."
    },
    {
        "anchor": "Multiphase Field Model of Cells on a Substrate: Multiphase field models have emerged as an important computational tool for\nunderstanding biological tissue while resolving single-cell properties. While\nthey have successfully reproduced many experimentally observed behaviors of\nliving tissue, the theoretical underpinnings have not been fully explored. We\nshow that a two-dimensional version of the model, which is commonly employed to\nstudy tissue monolayers, can be derived from a three-dimensional version in the\npresence of a substrate. We also show how viscous forces, which arise from\nfriction between different cells, can be included in the model. Finally, we\nnumerically simulate a tissue monolayer, and find that intercellular friction\ntends to solidify the tissue.",
        "positive": "From Frictional to Viscous Behavior: Three Dimensional Imaging and\n  Rheology of Gravitational Suspensions: We probe the three dimensional flow structure and rheology of gravitational\n(non-density matched) suspensions for a range of driving rates in a\nsplit-bottom geometry. We establish that for sufficiently slow flows, the\nsuspension flows as if it were a dry granular medium, and confirm recent\ntheoretical modeling on the rheology of split-bottom flows. For faster driving,\nthe flow behavior is shown to be consistent with the rheological behavior\npredicted by the recently developed \"inertial number approaches for suspension\nflows."
    },
    {
        "anchor": "Traction chain networks: Insights beyond force chain networks for\n  non-spherical particle systems: Force chain networks are generally applied in granular materials to gain\ninsight into inter-particle granular contact. For conservative spherical\nparticle systems, i.e. frictionless and undamped, force chains are information\ncomplete due to symmetries resulting from isotropy and constant curvature of a\nsphere. In fact, for conservative spherical particle systems, given the\ngeometry and material, the force chain network uniquely defines the contact\nstate that includes elastic forces, penetration distance, overlap volume,\ncontact areas and contact pressures in a particle system. This is, however, not\nthe case for conservative non-spherical particle systems. The reason is that a\nforce chain network is not sufficient to uniquely define the contact state in a\nconservative non-spherical particle system. Additional information is required\nto define the contact state of non-spherical granular systems. Traction chain\nnetworks are proposed to complement force chain networks for the improved\nquantification of the state of contact of a granular system.",
        "positive": "Crushing modes of aluminium tubes under axial compression: A numerical study of the crushing of circular aluminium tubes with and\nwithout aluminium foam fillers has been carried out to investigate their\nbuckling behaviours under axial compression. A crushing mode classification\nchart has been established for empty tubes. The influence of boundary\nconditions on crushing mode has also been investigated. The effect of foam\nfiller on the crushing mode of tubes filled with foam was then examined. The\npredicted results would assist the design of crashworthy tube components with\nthe preferred crushing mode with the maximum energy absorption."
    },
    {
        "anchor": "Packing Confined Hard Spheres Denser with Adaptive Prism Phases: We show that hard spheres confined between two parallel hard plates pack\ndenser with periodic adaptive prismatic structures which are composed of\nalternating prisms of spheres. The internal structure of the prisms adapts to\nthe slit height which results in close packings for a range of plate\nseparations, just above the distance where three intersecting square layers fit\nexactly between the plates. The adaptive prism phases are also observed in\nreal-space experiments on confined sterically stabilized colloids and in Monte\nCarlo simulations at finite pressure.",
        "positive": "Observation of magnetic structural universality using transverse NMR\n  relaxation: Transverse NMR relaxation from spins diffusing through a random magnetic\nmedium is sensitive to its structure on a mesoscopic scale. In particular, this\nresults in the time-dependent relaxation rate. We show analytically and\nnumerically that this rate approaches the long-time limit in a power-law\nfashion, with the exponent reflecting the disorder class of mesoscopic magnetic\nstructure. The spectral line shape acquires a corresponding non-analytic power\nlaw singularity at zero frequency. We experimentally detect a change in the\ndynamical exponent as a result of the transition into a maximally random jammed\nstate characterized by hyperuniform correlations."
    },
    {
        "anchor": "Crystallization in a sheared colloidal suspension: We study numerically the crystallization process in a supersaturated\nsuspension of repulsive colloidal particles driven by simple shear flow. The\neffect of the shear flow on crystallization is two-fold: while it suppresses\nthe initial nucleation, once a large enough critical nucleus has formed its\ngrowth is enhanced by the shear flow. Combining both effects implies an optimal\nstrain rate at which the overall crystallization rate has a maximum. To gain\ninsight into the underlying mechanisms, we employ a discrete state model\ndescribing the transitions between the local structural configurations around\nsingle particles. We observe a time-scale separation between these transitions\nand the overall progress of the crystallization allowing for an effective\nMarkovian description. By using this model, we demonstrate that the suppression\nof nucleation is due to the inhibition of a pre-structured liquid.",
        "positive": "Quantifying `local softness' in a simple liquid: Mutual information between local stress and local non-affine deformation is\nproposed as a collective field variable quantifying the {\\em local softness} of\nsoft materials. The liquid-solid transition in a simple liquid is considered as\na generic example of mechanical transformation through varying correlation\nbetween stress and deformation at the microscopic level. Probing through this\nnew measure, a liquid appears as a spatially heterogeneous medium of\ninteracting interconnected regions of varying softness. In contrast, the soft\nregions shrink to isolated spots in the background of a negligible mean\nsoftness in the case of solids. In this view, the thermodynamic transition\nbecomes purely geometric while keeping the essential mechanical information\nintact. Besides offering a general framework for understanding the mechanics of\nmaterials, this new approach can complement recent machine learning efforts by\nassigning physical meaning to their findings. Further, this collective variable\ncan be used on the fly during material characterization as both of its\ningredient variables are experimentally accessible."
    },
    {
        "anchor": "Manipulating bubbles with secondary Bjerknes forces: Gas bubbles in a sound field are submitted to a radiative force, known as the\nsecondary Bjerknes force. We propose an original experimental setup that allows\nus to investigate in details this force between two bubbles, as a function of\nthe sonication frequency, as well as the bubbles radii and distance. We report\nthe observation of both attractive and, more interestingly, repulsive Bjerknes\nforce, when the two bubbles are driven in antiphase. Our experiments show the\nimportance of taking multiple scattering into account, which leads to a strong\nacoustic coupling of the bubbles when their radii are similar. Our setup\ndemonstrates the accuracy of secondary Bjerknes forces for attracting or\nrepealing a bubble, and could lead to new acoustic tools for non contact\nmanipulation in microfluidic devices.",
        "positive": "Collective Transport of Magnetic Microparticles at a Fluid Interface\n  through Dynamic Self-Assembled Lattices: The transport of motile entities across modulated energy landscapes plays an\nimportant role in a range of phenomena in biology, colloidal science and\nsolid-state physics. Here, an easily implementable strategy that allows for the\ncollective and monitored transport of microparticles at fluid-fluid interfaces\nis introduced. Adsorbed magnetic microparticles are carried on time-dependent\nmagnetic potentials, generated by a dynamic self-assembled lattice of\ndifferent-sized magnetic particles. In such binary systems, the sudden\nreorientation of the applied field triggers the rapid exchange between\nattractive and repulsive configurations, enabling for the ballistic transfer of\nthe carriers through the lattice. As the number of motile entities increases,\nthe induced current increases, before reaching a maximum, while the loaded\ninterface gradually displays bidirectional transport. The described methodology\ncan be tuned through the applied field and exploited for the monitored guidance\nof adsorbed molecules on liquid surfaces, the segregation of colloidal\nmixtures, the induced motion of defects in photonic crystals or the design of\nnew self-assembled microrobots."
    },
    {
        "anchor": "Capillary filling of polymer chains in nanopores: We performed molecular dynamics simulations with a coarse-grained model to\ninvestigate the capillary filling dynamics of polymer chains in nanopores.\nShort chains fill slower than predicted by the Lucas-Washburn equation but long\nchains fill faster. The analysis shows that the combination of the confinement\neffect on the free energy of chains and the reduction of the effective radius\ndue to the \"dead zone\" slow down the imbibition. Reduction of the entanglements\nis the main factor behind the reversing dynamics because of the lower effective\nviscosity, which leads to a faster filling. This effect is enhanced in the\nsmaller capillary and more profound for longer chains. The observed increase in\nthe mean square radius of gyration during capillary filling provides a clear\nevidence of chain orientation, which leads to the decrease in the number of\nentanglements. For the scaling relation between the effective viscosity and the\ndegree of polymerization, we find the exponent will increase in the larger\nnanopore.",
        "positive": "The dynamics of a collapsing polyelectrolyte gel: We analyse the dynamics of different routes to collapse of a constrained\npolyelectrolyte gel in contact with an ionic bath. The evolution of the gel is\ndescribed by a model that incorporates non-linear elasticity, Stefan-Maxwell\ndiffusion and interfacial gradient free energy to account for phase separation\nof the gel. A bifurcation analysis of the homogeneous equilibrium states\nreveals three solution branches at low ion concentrations in the bath, giving\nway to only one above a critical ion concentration. We present numerical\nsolutions that capture both the spatial heterogeneity and the multiple\ntime-scales involved in the process of collapse. These solutions are\ncomplemented by two analytical studies. Firstly, a phase-plane analysis that\nreveals the existence of a depletion front for the transition from the highly\nswollen to the new collapsed equilibrium state. This depletion front is\ninitiated after the fast ionic diffusion has set the initial condition for this\ntime regime. Secondly, we perform a linear stability analysis about the\nhomogeneous states that show that for a range of ion concentrations in the\nbath, spinodal decomposition of the swollen state gives rise to localized\nsolvent-rich(poor) and, due to the electro-neutrality condition, ion-poor(rich)\nphases that coarsen on the route to collapse. This dynamics of a collapsing\npolyelectrolyte gel has not been described before."
    },
    {
        "anchor": "Impurity mediated nucleation in hexadecane-in-water emulsions: We report detailed nucleation studies on the liquid-to-solid transition of\nhexadecane using nearly monodisperse hexadecane-in-water emulsions. A careful\nconsideration of the kinetics of isothermal and nonisothermal freezing show\ndeviations from predictions of classical nucleation theory, if one assumes that\nthe emulsion droplet population is homogeneous. Similar deviations have been\nobserved previously. As an explanation, we propose a novel argument based on\nthe dynamic generation of droplet heterogeneity mediated by mobile impurities.\nThis proposal is in excellent agreement with existing data.",
        "positive": "Quantitative imaging of the complexity in liquid bubbles' evolution\n  reveals the dynamics of film retraction: The dynamics and stability of thin liquid films have fascinated scientists\nover many decades. Thin film flows are central to numerous areas of\nengineering, geophysics, and biophysics and occur over a wide range of length,\nvelocity, and liquid properties scales. In spite of many significant\ndevelopments in this area, we still lack appropriate quantitative experimental\ntools with the spatial and temporal resolution necessary for a comprehensive\nstudy of film evolution. We propose tackling this problem with a holographic\ntechnique that combines quantitative phase imaging with a custom setup designed\nto form and manipulate bubbles. The results, gathered on a model aqueous\npolymeric solution, provide an unparalleled insight into bubble dynamics\nthrough the combination of full-field thickness estimation, three-dimensional\nimaging, and fast acquisition time. The unprecedented level of detail offered\nby the proposed methodology will promote a deeper understanding of the\nunderlying physics of thin film dynamics."
    },
    {
        "anchor": "The Smectic Phase of Spherical-Fan Shaped Molecules. A Computer\n  Simulation Study: We have used Monte Carlo NPT computer simulations to study a system of\nspherical fan shaped particles made of three hard discs fused along a common\ndiameter. The calculated equation of state indicates a strong, entropy driven,\nfirst order transition from the isotropic phase to a layered phase that has the\nbasic characteristics of the usual smectic A mesophase but with strongly\ncorrelated rotations about the symmetry axes of neighbouring molecules.",
        "positive": "Discrete rearranging disordered patterns, part I: Robust statistical\n  tools in two or three dimensions: Discrete rearranging patterns include cellular patterns, for instance liquid\nfoams, biological tissues, grains in polycrystals; assemblies of particles such\nas beads, granular materials, colloids, molecules, atoms; and interconnected\nnetworks. Such a pattern can be described as a list of links between\nneighbouring sites. Performing statistics on the links between neighbouring\nsites yields average quantities (hereafter \"tools\") as the result of direct\nmeasurements on images. These descriptive tools are flexible and suitable for\nvarious problems where quantitative measurements are required, whether in two\nor in three dimensions. Here, we present a coherent set of robust tools, in\nthree steps. First, we revisit the definitions of three existing tools based on\nthe texture matrix. Second, thanks to their more general definition, we embed\nthese three tools in a self-consistent formalism, which includes three\nadditional ones. Third, we show that the six tools together provide a direct\ncorrespondence between a small scale, where they quantify the discrete\npattern's local distortion and rearrangements, and a large scale, where they\nhelp describe a material as a continuous medium. This enables to formulate\nelastic, plastic, fluid behaviours in a common, self-consistent modelling using\ncontinuous mechanics. Experiments, simulations and models can be expressed in\nthe same language and directly compared. As an example, a companion paper\n(Marmottant, Raufaste and Graner, joint paper) provides an application to foam\nplasticity."
    },
    {
        "anchor": "Proton spin dynamics in polymer melts: new perspectives for experimental\n  investigations of polymer dynamics: Significant progress was made in recent years in the understanding of the\nproton spin kinetics in polymer melts. Generally, the proton spin kinetics is\ndetermined by intramolecular and intermolecular magnetic dipole-dipole\ncontributions of proton spins. During many decades it was postulated that the\nmain contribution is a result of intramolecular magnetic dipole-dipole\ninteractions of protons belonging to the same polymer segment. It appears that\nthis postulate is far from reality. The relative weights of intra- and\nintermolecular contributions are time dependent and sensitive to details of\npolymer chain dynamics. It is shown that for isotropic models of polymer\ndynamics the influence of the intermolecular magnetic dipole-dipole\ninteractions increases faster with increasing evolution time (i.e. decreasing\nfrequency) than the corresponding influence of the intramolecular counterpart.\nOn the other hand, an inverted situation is predicted by the tube-reptation\nmodel: here the influence of the intramolecular magnetic dipole-dipole\ninteractions increases faster with time than the contribution from\nintermolecular interactions. The intermolecular contribution in the proton\nrelaxation of polymer melts can experimentally be isolated using the isotope\ndilution technique and this opens a new perspective for experimental\ninvestigations of polymer dynamics by proton NMR.",
        "positive": "Static and dynamic properties of large polymer melts in equilibrium: We present a detailed study of the static and dynamic behavior of long\nsemiflexible polymer chains in a melt. Starting from previously obtained fully\nequilibrated high molecular weight polymer melts [{\\it Zhang et al.} ACS Macro\nLett. 3, 198 (2014)] we investigate their static and dynamic scaling behavior\nas predicted by theory. We find that for semiflexible chains in a melt, results\nof the mean square internal distance, the probability distributions of the\nend-to-end distance, and the chain structure factor are well described by\ntheoretical predictions for ideal chains. We examine the motion of monomers and\nchains by molecular dynamics simulations using the ESPResSo++ package. The\nscaling predictions of the mean squared displacement of inner monomers, center\nof mass, and relations between them based on the Rouse and the reptation theory\nare verified, and related characteristic relaxation times are determined.\nFinally we give evidence that the entanglement length $N_{e,PPA}$ as determined\nby a primitive path analysis (PPA) predicts a plateau modulus,\n$G_N^0=\\frac{4}{5}(\\rho k_BT/N_e)$, consistent with stresses obtained from the\nGreen-Kubo relation. These comprehensively characterized equilibrium\nstructures, which offer a good compromise between flexibility, small $N_e$,\ncomputational efficiency, and small deviations from ideality provide ideal\nstarting states for future non-equilibrium studies."
    },
    {
        "anchor": "Normal viscosity and Viscous resuspension of non-Brownian suspensions: Normal stresses in sheared suspensions of non-Brownian particles are obtained\nfrom numerical simulations. The stresses are determined in homogeneous shear of\nnon-buoyant particles and by analyzing shear-induced resuspension of buoyant\nparticles in the framework of the suspension balance model (SBM). The\nconsistency of both approaches indicates that the SBM describes the steady\nstate properly. Though in agreement with most available experimental results,\nnone of previous empirical expressions for the normal stress can describe the\ndata in the whole range of volume fraction, and in particular in the\nsemi-dilute regime (25-35\\%) where the normal stress is less than expected. New\nexpressions are proposed. The results also highlight that the normal stress\nanisotropy depends on the volume fraction, and that lubrication interactions\nsignificantly contribute to the normal stress in the semi-dilute regime.",
        "positive": "Hydrodynamic lift of vesicles under shear flow in microgravity: The dynamics of a vesicle suspension in a shear flow between parallel plates\nhas been investigated under microgravity conditions, where vesicles are only\nsubmitted to hydrodynamic effects such as lift forces due to the presence of\nwalls and drag forces. The temporal evolution of the spatial distribution of\nthe vesicles has been recorded thanks to digital holographic microscopy, during\nparabolic flights and under normal gravity conditions. The collected data\ndemonstrates that vesicles are pushed away from the walls with a lift velocity\nproportional to $\\dot{\\gamma} R^3/z^2$ where $\\dot{\\gamma}$ is the shear rate,\n$R$ the vesicle radius and $z$ its distance from the wall. This scaling as well\nas the dependence of the lift velocity upon vesicle aspect ratio are consistent\nwith theoretical predictions by Olla [J. Phys. II France {\\bf 7}, 1533--1540\n(1997)]."
    },
    {
        "anchor": "Opto-mechanical system for the controlled growth of granular piles: The formation of sandpiles is a subject if interest in the field of granular\nmatter, but most experiments are unable to control the kinetic energy of the\ngrains added to the apex of the growing pile. In this short article, we\ndescribe an opto-mechanical system to grow granular piles by adding sand from a\nfixed distance above the apex of the pile. To achieve that, we use a laser beam\nthat detects the position of the apex and, as the pile grows, sends a feedback\nsignal to a mechanical device able to control the height of the sand delivey\nsystem above the pile.",
        "positive": "Multipolar expansion of the electrostatic interaction between charged\n  colloids at interfaces: The general form of the electrostatic potential around an arbitrarily charged\ncolloid at an interface between a dielectric and a screening phase (such as air\nand water, respectively) is analyzed in terms of a multipole expansion. The\nleading term is isotropic in the interfacial plane and varies with $d^{-3}$\nwhere $d$ is the in--plane distance from the colloid. The electrostatic\ninteraction potential between two arbitrarily charged colloids is likewise\nisotropic and $\\propto d^{-3}$, corresponding to the dipole--dipole interaction\nfirst found for point charges at water interfaces. Anisotropic interaction\nterms arise only for higher powers $d^{-n}$ with $n \\ge 4$."
    },
    {
        "anchor": "Entropic forces stabilize diverse emergent structures in colloidal\n  membranes: The depletion interaction mediated by non-adsorbing polymers promotes\ncondensation and assembly of repulsive colloidal particles into diverse\nhigher-order structures and materials. One example, with particularly rich\nemergent behaviors, is the formation of two-dimensional colloidal membranes\nfrom a suspension of filamentous $\\it{fd}$ viruses, which act as rods with\neffective repulsive interactions, and dextran, which acts as a condensing,\ndepletion-inducing agent. Colloidal membranes exhibit chiral twist even when\nthe constituent virus mixture lacks macroscopic chirality, change from a\ncircular shape to a striking starfish shape upon changing the chirality of\nconstituent rods, and partially coalesce via domain walls through which the\nviruses twist by $180^\\circ$. We formulate an entropically-motivated theory\nthat can quantitatively explain these experimental structures and measurements,\nboth previously published and newly performed, over a wide range of\nexperimental conditions. Our results elucidate how entropy alone, manifested\nthrough the viruses as Frank elastic energy and through the depletants as an\neffective surface tension, drives the formation and behavior of these diverse\nstructures. Our generalizable principles propose the existence of analogous\neffects in molecular membranes and can be exploited in the design of\nreconfigurable colloidal structures.",
        "positive": "Fluctuation induced interactions between domains in membranes: We study a model lipid bilayer composed of a mixture of two incompatible\nlipid types which have a natural tendency to segregate in the absence of\nmembrane fluctuations. The membrane is mechanically characterized by a local\nbending rigidity $\\kappa(\\phi)$ which varies with the average local lipid\ncomposition $\\phi$. We show, in the case where $\\kappa$ varies weakly with\n$\\phi$, that the effective interaction between lipids of the same type can\neither be everywhere attractive or can have a repulsive component at\nintermediate distances greater than the typical lipid size. When this\ninteraction has a repulsive component, it can prevent macro-phase separation\nand lead to separation in mesophases with a finite domain size. This effect\ncould be relevant to certain experimental and numerical observations of\nmesoscopic domains in such systems."
    },
    {
        "anchor": "Equation of State of Wet Granular Matter: A theory is derived for the nonequilibrium probability currents of the\ncapillary interaction which determines the pair correlation function near\ncontact. This yields an analytic expression for the equation of state, P =\nP(N/V,T), of wet granular matter for D=2 dimensions, valid in the complete\ndensity range from gas to jamming. Driven wet granular matter exhibits a\nvan-der-Waals-like unstable branch at granular temperatures T<T_c corresponding\nto a first order segregation transition of clusters. For the realistic rupture\nlength of the liquid bridge, s_crit=0.07 d, the critical point is located at\nT_c = 0.274 E_cb. While the critical temperature weakly depends on the rupture\nlength, the critical density phi_c is shown to scale with s_crit according to\ns_crit = 4d (sqrt(phi_J / phi_c) -1). The segregation transition is closely\nrelated to the precipitation of granular droplets reported for the free cooling\nof one-dimensional wet granular matter [Phys. Rev. Lett. 97, 078001 (2006)],\nand extends the effect to higher dimensional systems. Since the limiting case\nof sticky bonds, E_cb >> T, is of relevance for aggregation in general,\nsimulations have been performed which show very good agreement with the\ntheoretically predicted coordination K of capillary bonds as a function of the\nbond length s_crit. This result implies that particles that stick at the\nsurface, s_crit=0, form isostatic clusters.",
        "positive": "Sympathetic cooling and growth of a Bose-Einstein condensate: We study two sets of rate equations for sympathetic cooling of harmonically\ntrapped Bose gases. Calculations for mixtures of Na-Rb and Li-Cs show that both\nsets yield similar results for the cooling times. The equilibration rates are\nin fair agreement with each other and differ considerably from classical rates.\nThe onset of Bose-Einstein condensation is rather sudden and non-exponential in\ntime, and the growth of the condensate differs for the two different mixtures\nwe studied."
    },
    {
        "anchor": "Hierarchical defect-induced condensation in active nematics: Topological defects play a central role in the formation and organization of\nvarious biological systems. Historically, such nonequilibrium defects have been\nmainly studied in the context of homogeneous active nematics. Phase-separated\nsystems, in turn, are known to form dense and dynamic nematic bands, but\ntypically lack topological defects. In this paper, we use agent-based\nsimulations of weakly aligning, self-propelled polymers and demonstrate that\ncontrary to the existing paradigm phase-separated active nematics form ${-1/2}$\ndefects. Moreover, these defects, emerging due to interactions among dense\nnematic bands, constitute a novel second-order collective state. We investigate\nthe morphology of defects in detail and find that their cores correspond to a\nstrong increase in density, associated with a condensation of nematic fluxes.\nUnlike their analogs in homogeneous systems, such condensed defects form and\ndecay in a different way and do not involve positively charged partners. We\nadditionally observe and characterize lateral arc-like structures that separate\nfrom a band's bulk and move in transverse direction. We show that the key\ncontrol parameters defining the route from stable bands to the coexistence of\ndynamic lanes and defects are the total density of particles and their path\npersistence length. We introduce a hydrodynamic theory that qualitatively\nrecapitulates all the main features of the agent-based model, and use it to\nshow that the emergence of both defects and arcs can be attributed to the same\nanisotropic active fluxes. Finally, we present a way to artificially engineer\nand position defects, and speculate about experimental verification of the\nprovided model.",
        "positive": "Mapping Disorder in Entropically Ordered Crystals: Systems of hard shapes crystallize due to entropy. How is entropy distributed\namong translational and rotational microscopic contributions? We answer this\nquestion by decomposing thermal fluctuation of crystals of hard hexagons into\ncollective modes, a generalization and quantification of the Onsager picture of\nhard rod liquid crystals. We show that at densities both near densest packing\nand near the solid-hexatic melting transition, solids of hard regular hexagons\nhold most of their entropy in translational degrees of freedom."
    },
    {
        "anchor": "Transient nanobubbles in short-time electrolysis: Water electrolysis in a microsystem is observed and analyzed on a short-time\nscale ~10 us. Very unusual properties of the process are stressed. An extremely\nhigh current density is observed because the process is not limited by the\ndiffusion of electroactive species. The high current is accompanied by a high\nrelative supersaturation S>1000 that results in homogeneous nucleation of\nbubbles. On the short-time scale only nanobubbles can be formed. These\nnanobubbles densely cover the electrodes and aggregate at a later time to\nmicrobubbles. The effect is significantly intensified with a small increase of\ntemperature. Application of alternating polarity voltage pulses produces\nbubbles containing a mixture of hydrogen and oxygen. Spontaneous reaction\nbetween gases is observed for stoichiometric bubbles with the size smallaer\nthan 150 nm. Such bubbles disintegrate violently affecting the surface of\nelectrodes.",
        "positive": "Comment on \"Nonlocal statistical field theory of dipolar particles in\n  electrolyte solutions\" by Y.A. Budkov: The article by Budkov introduces a nonlocal field-theoretic model of\nsolvent-explicit electrostatics. Despite giving a detailed introduction to the\nearly literature on the topic, the article misses out on a series of articles\nthat we published several years ago. Consequently, the manuscript essentially\nrederives without mention several results that were derived by us for the first\ntime."
    },
    {
        "anchor": "Random blisters on stickers: metrology through defects: Blisters are commonly observed when an adhesive sheet is carelessly deposited\non a plate. Although such blisters are usually not desired for practical\napplications, we show through model experiments on angular blisters how\nmaterial properties can be deduced from height profile measurements. In\nparticular the typical curvature of the crests is found proportional to an\nelasto-capillary length that compares the bending stiffness of the sheet with\nadhesion energy. In addition, the radius of the tip allows to estimate the\nproduct of this length with the thickness of the sheet. The relevance of these\nresults to realistic random configurations is finally confirmed.",
        "positive": "Spontaneous Demixing of Binary Colloidal Flocks: Population heterogeneity is ubiquitous among active living systems, but\nlittle is known about its role in determining their spatial organization and\nlarge-scale dynamics. Combining evidence from synthetic active fluids assembled\nfrom self-propelled colloidal particles along with theoretical predictions at\nthe continuum scale, we demonstrate the spontaneous demixing of binary polar\nliquids within circular confinement. Our analysis reveals how both active speed\nheterogeneity and non-reciprocal repulsive interactions lead to self-sorting\nbehavior. By establishing general principles for the self-organization of\nbinary polar liquids, our findings highlight the specificity of multi-component\nactive systems."
    },
    {
        "anchor": "Dynamics of Internal Stresses and Scaling of Strain Recovery in an Aging\n  Colloidal Gel: We monitor the relaxation of internal stresses in a fractal colloidal gel on\ncessation of flow and find a weak power law decay, $\\sigma_i \\sim t^{-\\alpha}$\nover 5 decades of time where $\\alpha \\approx 0.07$. The system exhibits\nphysical aging of the elastic modulus, $G' \\sim t^{\\beta}$, with $\\beta \\approx\n\\alpha$. Imposition of zero stress after waiting time $t_w$ results in strain\nrecovery as the system relaxes without constraint. Remarkably, recoveries at\ndifferent $t_w$ can be shifted to construct a master curve where data are\nscaled vertically by $1/\\sigma_i(t_w)$ and plotted horizontally as\n$(t-t_w)/t_w^{\\mu}$ where $\\mu\\approx 1.25$, indicative of a super-aging\nresponse.",
        "positive": "Enhanced contact flexibility from nanoparticles in capillary suspensions: Hypothesis: Sample-spanning particle networks are used to induce structure\nand a yield stress, necessary for 3D printing of porous ceramics and paints. In\ncapillary suspensions, a small quantity of immiscible secondary fluid is\nincorporated into a suspension. By further adding nanoparticles with a range of\nhydrophobicities, the structure of the bridges and microparticle-microparticle\ncontacts should be modified, resulting in a tunable yield stress and shear\nmoduli. Moreover, the compressibility of these samples, important in many\nprocessing and application steps, should be sensitive to these changes.\n  Experiment: The nanoparticle hydrophobicity was altered and their position\nrelative to the microparticles and the bridges was examined using confocal\nmicroscopy where the correlation between bridge size and network structure was\nobserved. A step-wise uniaxial compression test on the confocal was conducted\nto monitor the microparticle movement and structural changes between capillary\nsuspension networks with and without nanoparticles.\n  Findings: Our observation suggests that nanoparticles induce the formation of\nthin liquid films on the surface of the microparticles, mitigating contact line\npinning and promoting internal liquid exchange. Additionally, nanoparticles at\nmicroparticle contact regions further diminish Hertzian contact, enhancing the\ncapacity for rearrangement. These effects enhance microparticle movement,\nnarrowing the bridge size distribution."
    },
    {
        "anchor": "Shape-induced pairing of spheroidal squirmers: The \"squirmer model\" is a classical hydrodynamic model for the motion of\ninterfacially-driven microswimmers, such as self-phoretic colloids or volvocine\ngreen algae. To date, most studies using the squirmer model have considered\nspherical particles with axisymmetric distribution of surface slip. Here, we\ndevelop a general approach to the pairing and scattering dynamics of two\nspheroidal squirmers. We assume that the direction of motion of the squirmers\nis restricted to a plane, which is approximately realized in many experimental\nsystems. In the framework of an analytically tractable kinetic model, we\npredict that, for identical squirmers, an immotile \"head-to-head\" configuration\nis stable only when the particles have oblate shape and a non-axisymmetric\ndistribution of surface slip. We also obtain conditions for stability of a\nmotile \"head-to-tail\" configuration: for instance, the two particles must have\nunequal self-propulsion velocities. Our analytical predictions are compared\nagainst detailed numerical calculations obtained using the boundary element\nmethod.",
        "positive": "Critical Temperature and Condensate Fraction of the Trapped Interacting\n  Bose Gas with Finite-size Effects: The critical temperature and condensate fraction of a trapped interacting\nBose gas are investigated when both atom-atom interaction and finite-size\neffects are taken into account. Canonical ensemble is used to obtain the\nequations on the condensate fraction for the trapped interacting Bose gas near\nand below the critical temperature. In our approaches corrections due to\natom-atom interaction and finite-size effects are obtained simultaneously for\nthe critical temperature and condensate fraction of the system. Analytical\nhigh-order correction to the condensate fraction is given in this work."
    },
    {
        "anchor": "Soft beams: when capillarity induces axial compression: We study the interaction of an elastic beam with a liquid drop in the case\nwhere bending and extensional effects are both present. We use a variational\napproach to derive equilibrium equations and constitutive relation for the\nbeam. This relation is shown to include a term due to surface energy in\naddition of the classical Young's modulus term, leading to a modification of\nHooke's law. At the triple point where solid, liquid, and vapor phases meet we\nfind that the external force applied on the beam is parallel to the\nliquid-vapor interface. Moreover, in the case where solid-vapor and\nsolid-liquid interface energies do not depend on the extension state of the\nbeam, we show that the extension in the beam is continuous at the triple point\nand that the wetting angle satisfy the classical Young-Dupr\\'e relation.",
        "positive": "Characterization of active matter in dense suspensions with heterodyne\n  laser Doppler velocimetry: We present a novel approach for characterizing the properties and performance\nof active matter in dilute suspension as well as in crowded environments. We\nuse Super-Heterodyne Laser-Doppler-Velocimetry (SH-LDV) to study large\nensembles of catalytically active Janus particles moving under UV-illumination.\nSH-LDV facilitates a model-free determination of the swimming speed and\ndirection, with excellent ensemble averaging. In addition we obtain\nin-formation on the distribution of the catalytic activity. Moreover, SH-LDV\noperates away from walls and permits a facile correction for multiple\nscattering contributions. It thus allows for stud-ies of concentrated\nsuspensions of swimmers or of systems where swimmers propel actively in an\nenvironment crowded by passive particles. We demonstrate the versatility and\nthe scope of the method with a few selected examples. We anticipate that SH-LDV\ncomplements estab-lished methods and paves the way for systematic measurements\nat previously inaccessible boundary conditions."
    },
    {
        "anchor": "Dissipation-consistent modelling and classification of extended\n  plasticity formulations: A unified classification framework for models of extended plasticity is\npresented. The models include well known micromorphic and strain gradient\nplasticity formulations. A unified treatment is possible due to the\nrepresentation of strain gradient plasticity as an Eringen-type micromorphic\ncontinua. The classification is based on the form of the energetic and\ndissipative model structures and exploits the framework of\ndissipation-consistent modelling to elucidate the flow relation and yield\ncondition. Models are identified as either serial or parallel. This designation\nis also applicable to familiar models of classical plasticity. Particular\nattention is paid to the rate-dependent problem arising from the choice of a\nsmooth dissipation potential. The inability to locally determine the region of\nadmissible stresses for the non-smooth (rate-independent) parallel models of\nplasticity is made clear.",
        "positive": "Avalanches, loading and finite size effects in 2D amorphous plasticity:\n  results from a finite element model: Crystalline plasticity is strongly interlinked with dislocation mechanics and\nnowadays is relatively well understood. Concepts and physical models of plastic\ndeformation in amorphous materials on the other hand - where the concept of\nlinear lattice defects is not applicable - still are lagging behind. We\nintroduce an eigenstrain-based finite element lattice model for simulations of\nshear band formation and strain avalanches. Our model allows us to study the\ninfluence of surfaces and finite size effects on the statistics of avalanches.\nWe find that even with relatively complex loading conditions and open boundary\nconditions, critical exponents describing avalanche statistics are unchanged,\nwhich validates the use of simpler scalar lattice-based models to study these\nphenomena."
    },
    {
        "anchor": "Sampling efficiency of transverse forces in dense liquids: Sampling the Boltzmann distribution using forces that violate detailed\nbalance can be faster than with the equilibrium evolution, but the acceleration\ndepends on the nature of the nonequilibrium drive and the physical situation.\nHere, we study the efficiency of forces transverse to energy gradients in dense\nliquids through a combination of techniques: Brownian dynamics simulations,\nexact infinite-dimensional calculation and a mode-coupling approximation. We\nfind that the sampling speedup varies non-monotonically with temperature, and\ndecreases as the system becomes more glassy. We characterize the interplay\nbetween the distance to equilibrium and the efficiency of transverse forces by\nmeans of odd transport coefficients.",
        "positive": "Soft quasicrystals - Why are they stable?: In the last two years we have witnessed the exciting experimental discovery\nof soft matter with nontrivial quasiperiodic long-range order - a new form of\nmatter termed a soft quasicrystal. Two groups have independently discovered\nsuch order in soft matter: Zeng et al. [Nature 428 (2004) 157] in a system of\ndendrimer liquid crystals; and Takano et al. [J. Polym. Sci. Polym. Phys. 43\n(2005) 2427] in a system of ABC star-shaped polymers. These newly discovered\nsoft quasicrystals not only provide exciting platforms for the fundamental\nstudy of both quasicrystals and of soft matter, but also hold the promise for\nnew applications based on self-assembled nanomaterials with unique physical\nproperties that take advantage of the quasiperiodicity, such as complete and\nisotropic photonic band-gap materials. Here we provide a concise review of the\nemerging field of soft quasicrystals, suggesting that the existence of two\nnatural length-scales, along with 3-body interactions, may constitute the\nunderlying source of their stability."
    },
    {
        "anchor": "Differential Variance Analysis of soft glassy materials: a direct method\n  to quantify and visualize dynamic heterogeneities: Many amorphous materials show spatially heterogenous dynamics, as different\nregions of the same system relax at different rates. Such a signature, known as\nDynamic Heterogeneity, has been crucial to understand the jamming transition in\nsimple model systems and, currently, is considered very promising to\ncharacterize more complex fluids of industrial and biological relevance.\nUnfortunately, measurements of dynamic heterogeneities typically require\nsophysticated experimental set-ups and are performed by few specialized groups.\nIt is now possible to quantitatively characterize the relaxation process and\nthe emergence of dynamic heterogeneities using a straightforward method, here\nvalidated on video microscopy data of hard-sphere colloidal glasses. We call\nthis method Differential Variance Analysis (DVA), since it focuses on the\nvariance of the differential frames, obtained subtracting images at different\nlag-times. Moreover, direct visualization of dynamic heterogeneities naturally\nappears in the differential frames, when the lag-time is set to the one\ncorresponding to the maximum dynamic susceptibility. This approach opens the\nway to effectively characterize and tailor a wide variety of soft materials,\nfrom complex formulated products to biological tissues.",
        "positive": "Harmonically confined, semiflexible polymer in a channel: response to a\n  stretching force and spatial distribution of the endpoints: We consider an inextensible, semiflexible polymer or worm-like chain which is\nconfined in the transverse direction by a parabolic potential and subject to a\nlongitudinal force at the ends, so that the polymer is stretched out and\nbackfolding is negligible. Simple analytic expressions for the partition\nfunction, valid in this regime, are obtained for chains of arbitrary length\nwith a variety of boundary conditions at the ends. The spatial distribution of\nthe end points or radial distribution function is also analyzed."
    },
    {
        "anchor": "Two-phase crystallisation in a carpet of inertial spinners: We study the dynamics of torque driven spherical spinners settled on a\nsurface, and demonstrate that hydrodynamic interactions at finite Reynolds\nnumbers can lead to a concentration dependent and non-uniform crystallisation.\nAt semi-dilute concentrations, we observe a rapid formation of a uniform\nhexagonal structure in the spinner monolayer. We attribute this to repulsive\nhydrodynamic interactions created by the secondary flow of the spinning\nparticles. Increasing the surface coverage leads to a state with two\nco-existing spinner densities. The uniform hexagonal structure deviates into a\nhigh density crystalline structure surrounded by a continuous lower density\nhexatically ordered state. We show that this phase separation occurs due to a\nnon-monotonic hydrodynamic repulsion, arising from a concentration dependent\nspinning frequency.",
        "positive": "Orientations of the lamellar phase of block copolymer melts under\n  oscillatory shear flow: We develop a theory to describe the reorientation phenomena in the lamellar\nphase of block copolymer melt under reciprocating shear flow. We show that\nsimilar to the steady-shear, the oscillating flow anisotropically suppresses\nfluctuations and gives rise to the parallel-perpendicular orientation\ntransition. The experimentally observed high-frequency reverse transition is\nexplained in terms of interaction between the melt and the shear-cell walls."
    },
    {
        "anchor": "Kibble-Zurek mechanism in curved elastic surface crystals: Topological defects shape the material and transport properties of physical\nsystems. Examples range from vortex lines in quantum superfluids,\ndefect-mediated buckling of graphene, and grain boundaries in ferromagnets and\ncolloidal crystals, to domain structures formed in the early universe. The\nKibble-Zurek (KZ) mechanism describes the topological defect formation in\ncontinuous non-equilibrium phase transitions with a constant finite quench\nrate. Universal KZ scaling laws have been verified experimentally and\nnumerically for second-order transitions in planar Euclidean geometries, but\ntheir validity for discontinuous first-order transitions in curved and\ntopologically nontrivial systems still poses an open question. Here, we use\nrecent experimentally confirmed theory to investigate topological defect\nformation in curved elastic surface crystals formed by stress-quenching a\nbilayer material. Studying both spherical and toroidal crystals, we find that\nthe defect densities follow KZ-type power laws independent of surface geometry\nand topology. Moreover, the nucleation sequences agree with recent experimental\nobservations for spherical colloidal crystals. These results suggest that KZ\nscaling laws hold for a much broader class of dynamical phase transitions than\npreviously thought, including non-thermal first-order transitions in non-planar\ngeometries.",
        "positive": "Run-and-tumble in a crowded environment: persistent exclusion process\n  for swimmers: The effect of crowding on the run-and-tumble dynamics of swimmers such as\nbacteria is studied using a discrete lattice model of mutually excluding\nparticles that move with constant velocity along a direction that is randomized\nat a rate $\\alpha$. In stationary state, the system is found to break into\ndense clusters in which particles are trapped or stopped from moving. The\ncharacteristic size of these clusters predominantly scales as $\\alpha^{-0.5}$\nboth in 1D and 2D. For a range of densities, due to cooperative effects, the\nstopping time scales as ${\\cal T}_{1d}^{0.85}$ and as ${\\cal T}_{2d}^{0.8}$,\nwhere ${\\cal T}_d$ is the diffusive time associated with the motion of cluster\nboundaries. Our findings might be helpful in understanding the early stages of\nbiofilm formation."
    },
    {
        "anchor": "The measurement of Navier slip on individual nanoparticles in liquid: The Navier slip condition describes the motion of a liquid, relative to a\nneighboring solid surface, with its characteristic Navier slip length being a\nconstitutive property of the solid-liquid interface. Measurement of this slip\nlength is complicated by its small magnitude, expected in the nanometer range\nbased on molecular simulations. Here, we report an experimental technique that\ninterrogates the Navier slip length on individual nanoparticles immersed in\nliquid, with sub-nanometer precision. Proof-of-principle experiments on\nindividual, citrate-stabilized, gold nanoparticles in water give a constant\nslip length of 2.7$\\pm$0.6 nm (95% C.I.) - independent of particle size.\nAchieving this feature of size independence is central to any measurement of\nthis constitutive property, which is facilitated through the use of individual\nparticles of varying radii. This demonstration motivates studies that can now\nvalidate the wealth of existing molecular simulation data on slip.",
        "positive": "Substrate Adhesion of a Nongrafted Flexible Polymer in a Cavity: In a contact density chain-growth study we investigate the\nsolubility-temperature pseudo-phase diagram of a lattice polymer in a cavity\nwith an attractive surface. In addition to the main phases of adsorbed and\ndesorbed conformations we find numerous subphases of collapsed and expanded\nstructures."
    },
    {
        "anchor": "Ordered domains in sheared dense suspensions: the link to viscosity and\n  the disruptive effect of friction: Monodisperse suspensions of Brownian colloidal spheres crystallize at high\ndensities, and ordering under shear has been observed at densities below the\ncrystallization threshold. We perform large-scale simulations of a model\nsuspension containing over $10^5$ particles to quantitatively study the\nordering under shear and to investigate its link to the rheological properties\nof the suspension. We find that at high rates, for $Pe>1$, the shear flow\ninduces an ordering transition that significantly decreases the measured\nviscosity. This ordering is analyzed in terms of the development of layering\nand planar order, and we determine that particles are packed into hexagonal\ncrystal layers (with numerous defects) that slide past each other. By computing\nlocal $\\psi_6$ and $\\psi_4$ order parameters, we determine that the defects\ncorrespond to chains of particles in a square-like lattice. We compute the\nindividual particle contributions to the stress tensor and discover that the\nlargest contributors to the shear stress are primarily located in these lower\ndensity, defect regions. The defect structure enables the formation of\ncompressed chains of particles to resist the shear, but these chains are\ntransient and short-lived. The inclusion of a contact friction force allows the\nstress-bearing structures to grow into a system-spanning network, thereby\ndisrupting the order and drastically increasing the suspension viscosity.",
        "positive": "Growth of aqueous foam on flexible membranes: In this paper, I study the coarsening dynamics of two-dimensional dry foam\nsandwiched by deformable membranes. The time-varying deformation of the\nconfining membranes gives rise to a significant alteration in the evolution of\npolygonal cells of bubbles when compared to the case of rigid membranes. This\nalteration is attributed to the correlation between the rate of inter-cell gas\ntransfer and temporal fluctuation in surface curvature within a cell domain.\nThe existing material constants are referred to understand the utility of the\ncorrelation effect toward the artificial control of the coarsening dynamics."
    },
    {
        "anchor": "Unwinding Dynamics of a Helically Wrapped Polymer: We study the rotational dynamics of a flexible polymer initially wrapped\naround a rigid rod and unwinding from it. This dynamics is of interest in\nseveral problems in biology and constitutes a fundamental instance of polymer\nrelaxation from a state of minimal entropy. We investigate the dynamics of\nseveral quantities such as the total and local winding angles and metric\nquantities. The results of simulations performed in two and three dimensions,\nwith and without self-avoidance, are explained by a theory based on scaling\narguments and on a balance between frictional and entropic forces. The early\nstage of the dynamics is particularly rich, being characterized by three\ncoexisting phases.",
        "positive": "Peierls-Nabarro Barrier and Protein Loop Propagation: When a self-localized quasiparticle excitation propagates along a discrete\none dimensional lattice, it becomes subject to a dissipation that converts the\nkinetic energy into lattice vibrations. Eventually the kinetic energy does no\nlonger enable the excitation to cross over the minimum energy barrier between\nneighboring sites, and the excitation becomes localized within a lattice cell.\nIn the case of a protein, the lattice structure consists of the C-alpha\nbackbone. The self-localized quasiparticle excitation is the elemental building\nblock of loops. It can be modeled by a kink which solves a variant of the\ndiscrete non-linear Schroedinger equation (DNLS). We study the propagation of\nsuch a kink in the case of protein G related albumin-binding domain, using the\nUNRES coarse-grained molecular dynamics force field. We estimate the height of\nthe energy barriers the kink needs to cross over, in order to propagate along\nthe backbone lattice. We analyse how these barriers gives rise to both stresses\nand reliefs which control the kink movement. For this, we deform a natively\nfolded protein structure by parallel translating the kink along the backbone\naway from its native position. We release the transposed kink, and we follow\nhow it propagates along the backbone towards the native location. We observe\nthat the dissipative forces which are exerted on the kink by the various energy\nbarriers, have a pivotal role in determining how a protein folds towards its\nnative state."
    },
    {
        "anchor": "Sequence determines degree of knottedness in a coarse-grained protein\n  model: Knots are abundant in globular homopolymers but rare in globular proteins. To\nshed new light on this long-standing conundrum, we study the influence of\nsequence on the formation of knots in proteins under native conditions within\nthe framework of the hydrophobic-polar (HP) lattice protein model. By employing\nlarge scale Wang-Landau simulations combined with suitable Monte Carlo trial\nmoves we show that, even though knots are still abundant on average, sequence\nintroduces large variability in the degree of self-entanglements. Moreover, we\nare able to design sequences which are either almost always or almost never\nknotted. Our findings serve as proof of concept that the introduction of just\none additional degree of freedom per monomer (in our case sequence) facilitates\nevolution towards a protein universe in which knots are rare.",
        "positive": "Effect of Branching on Phase Behaviors of ABC Triblock Copolymers in\n  Nonfrustrated Systems: The phase behavior of linear dendritic triblock copolymer melts(AB2C4) is\nstudied by self-consistent-field theory (SCFT) in order to find the effects of\nbranching on the phase behavior of ABC linear triblock copolymer melts. We\nfocus on a nonfrustrated parameters that \\c{hi}NAB=\\c{hi}NBC=\\c{hi}NAC=40 where\nA/C interface will not form. Frank-Kasper phases, asymmetric alternative sphere\nas well as traditional phases observed in diblock copolymer melts are found to\nbe stable in the calculation."
    },
    {
        "anchor": "Room temperature study of a strain-induced electronic superstructure on\n  a magnetite (111) surface: A magnetite (Fe3O4) single crystal (111) surface has been studied at various\noxygen-iron surface stoichiometries. The stoichiometry was modified by\ncontrolling the in-situ sample anneal conditions. We have found the conditions\nthat lead to the formation of an oxygen-rich surface that forms a\nquasi-hexagonal superstructure with a 42A periodicity. The superstructure is\nhighly regular and was observed by both LEED and STM. The superstructure\nconsists of three regions, two of which have identical atomic scale structures\nwith a periodicity of 2.8A, and a third having a periodicity that is about 10%\nlarger (3.1A). The subtle difference in the atomic periodicities between the\nthree areas results from the modulation of intrinsic strain developed along the\nsurface. The superstructure results from electronic effects rather than being a\nmosaic of different iron oxide terminations. The onset of the superstructure is\nsensitive to the surface stoichiometry. From our results we could estimate the\ncritical density of defects leading to the disappearance of the superstructure.\nWe have modelled the experimental results and calculated the electron density\nusing a DFT algorithm. The model clearly shows the development of strain along\nthe surface.",
        "positive": "Relaxation and Recovery in Hydrogel Friction on Smooth Surfaces: \\textbf{Background} Hydrogels are crosslinked polymer networks that can\nabsorb and retain a large fraction of liquid. Near a critical sliding velocity,\nhydrogels pressed against smooth surfaces exhibit time-dependent frictional\nbehavior occurring over multiple timescales, yet the origin of these dynamics\nis unresolved. \\textbf{Objective} Here, we characterize this time-dependent\nregime and show that it is consistent with two distinct molecular processes:\nsliding-induced relaxation and quiescent recovery. \\textbf{Methods} Our\nexperiments use a custom pin-on-disk tribometer to examine poly(acrylic acid)\nhydrogels on smooth poly(methyl methacrylate) surfaces over a variety of\nsliding conditions, from minutes to hours. \\textbf{Results} We show that at a\nfixed sliding velocity, the friction coefficient decays exponentially and\nreaches a steady-state value. The time constant associated with this decay\nvaries exponentially with the sliding velocity, and is sensitive to any\nprecedent frictional shearing of the interface. This process is reversible;\nupon cessation of sliding, the friction coefficient recovers to its original\nstate. We also show that the initial direction of shear can be imprinted as an\nobservable \"memory\", and is visible after 24 hrs of repeated frictional\nshearing. \\textbf{Conclusions} We attribute this behavior to nanoscale\nextension and relaxation dynamics of the near-surface polymer network, leading\nto a model of frictional relaxation and recovery with two parallel timescales."
    },
    {
        "anchor": "The role of structure and entropy in determining differences in dynamics\n  for glass formers with different interaction potentials: We present a study of two model liquids with different interaction\npotentials, exhibiting similar structure but significantly different dynamics\nat low temperatures. By evaluating the configurational entropy, we show that\nthe differences in the dynamics of these systems can be understood in terms of\ntheir thermodynamic differences. Analyzing their structure, we demonstrate that\ndifferences in pair correlation functions between the two systems, through\ntheir contribution to the entropy, dominate the differences in their dynamics,\nand indeed overestimate the differences. Including the contribution of higher\norder structural correlations to the entropy leads to smaller estimates for the\nrelaxation times, as well as smaller differences between the two studied\nsystems.",
        "positive": "Finite-Thickness and Charge Relaxation in Double-Layer Interactions: We extend the classical Gouy-Chapman model of two planar parallel interacting\ndouble-layers, which is used as a first approximation to describe the force\nbetween colloidal particles, by considering the finite-thickness of the\ncolloids. The formation of two additional double layers due to this finite\nthickness, modifies the interaction force compared to the Gouy-Chapman case, in\nwhich the colloids are semi-infinite objects. In this paper we calculate this\ninteraction force and some other size-dependent properties using a mean field\nlevel of description, based on the Poisson-Boltzmann (PB) equation. We show\nthat in the case of finite-size colloids, this equation can be set in a closed\nform depending on the geometrical parameters and on their surface charge. The\ncorresponding linear (Debye-Huckel) theory and the well-known results for\nsemi-infinite colloids are recovered from this formal solution after taking\nappropriate limits. We use a density functional corresponding to the PB level\nof description to show how in the case when the total colloidal charge is\nfixed, it redistribute itself on their surfaces to minimize the energy of the\nsystem depending on the afore mentioned parameters. We study how this charge\nrelaxation affects the colloidal interactions."
    },
    {
        "anchor": "Stress-induced ordering of two-dimensional packings of elastic spheres: Packing of particles in confined environments is a common problem in multiple\nfields. Here, based on the two-dimensional Hertzian particle model, we study\nthe packing of deformable spherical particles under compression, and reveal the\ncrucial role of stress as an ordering field in regulating particle arrangement.\n  Specifically, under increasing compression, the squeezed particles\nspontaneously organize into regular packings in the sequence of triangular and\nsquare lattices, pentagonal tessellation, and the reentrant triangular lattice.\nThe rich ordered patterns and complex structures revealed in this work suggest\na fruitful organizational strategy based on the interplay of external stress\nand intrinsic elastic instability of particle arrays.",
        "positive": "A theory for the dynamics of dense systems of athermal self-propelled\n  particles: We present a derivation of a recently proposed theory for the time dependence\nof density fluctuations in stationary states of strongly interacting, athermal,\nself-propelled particles. The derivation consists of two steps. First, we start\nfrom the equation of motion for the joint distribution of particles' positions\nand self-propulsions and we integrate out the self-propulsions. In this way we\nderive an approximate, many-particle evolution equation for the probability\ndistribution of the particles' positions. Second, we use this evolution\nequation to describe the time dependence of steady-state density correlations.\nWe derive a memory function representation of the density correlation function\nand then we use a factorization approximation to obtain an approximate\nexpression for the memory function. In the final equation of motion for the\ndensity correlation function the non-equilibrium character of the active system\nmanifests itself through the presence of a new steady-state correlation\nfunction that quantifies spatial correlations of the velocities of the\nparticles. This correlation function enters into the frequency term, and thus\nit describes the dependence of the short-time dynamics on the properties of the\nself-propulsions. More importantly, the correlation function of particles'\nvelocities enters into the vertex of the memory function and through the vertex\nit modifies the long-time glassy dynamics."
    },
    {
        "anchor": "Applying GSH to a Wide Range of Experiments in Granular Media: Granular solid hydrodynamics (GSH) is a continuum-mechanical theory for\ngranular media, the range of which is shown in this paper. Simple, frequently\nanalytic solutions are related to classic observations at different shear\nrates, including: (i)~static stress distribution, clogging; (ii)~elasto-plastic\nmotion: loading and unloading, approach to the critical state, angle of\nstability and repose; (iii)~rapid dense flow: the $\\mu$-rheology, Bagnold\nscaling and the stress minimum; (iv)~elastic waves, compaction, wide and narrow\nshear band. Less conventional experiments have also been considered: shear\njamming, creep flow, visco-elastic behavior and nonlocal fluidization. With all\nthese phenomena ordered, related, explained and accounted for, though\nfrequently qualitatively, we believe that GSH may be taken as a unifying\nframework, providing the appropriate macroscopic vocabulary and mindset that\nhelp one coming to terms with the breadth of granular physics.",
        "positive": "Soft swimming: Exploiting deformable interfaces for low-Reynolds number\n  locomotion: Reciprocal movement cannot be used for locomotion at low-Reynolds number in\nan infinite fluid or near a rigid surface. Here we show that this limitation is\nrelaxed for a body performing reciprocal motions near a deformable interface.\nUsing physical arguments and scaling relationships, we show that the\nnonlinearities arising from reciprocal flow-induced interfacial deformation\nrectify the periodic motion of the swimmer, leading to locomotion. Such a\nstrategy can be used to move toward, away from, and parallel to any deformable\ninterface as long as the length scales involved are smaller than intrinsic\nscales, which we identify. A macro-scale experiment of flapping motion near a\nfree surface illustrates this new result."
    },
    {
        "anchor": "Polyelectrolyte Condensation Induced by Linear Cations: We examine the role of the condensing agent in the formation of\npolyelectrolyte bundles, via grand-canonical Monte Carlo simulations. Following\nrecent experiments we use linear, rigid divalent cations of various lengths to\ninduce condensation. Our results clarify and explain the experimental results\nfor short cations. For longer cations we observe novel condensation behavior\nowing to alignment of the cations. We also study the role of the\npolyelectrolyte surface charge density, and find a nonmonotonic variation in\nbundle stability. This nonmonotonicity captures two trends that have been\nobserved in separate experiments.",
        "positive": "DNA nanotechnology: understanding and optimisation through simulation: DNA nanotechnology promises to provide controllable self-assembly on the\nnanoscale, allowing for the design of static structures, dynamic machines and\ncomputational architectures. In this article I review the state-of-the art of\nDNA nanotechnology, highlighting the need for a more detailed understanding of\nthe key processes, both in terms of theoretical modelling and experimental\ncharacterisation. I then consider coarse-grained models of DNA, mesoscale\ndescriptions that have the potential to provide great insight into the\noperation of DNA nanotechnology if they are well designed. In particular, I\ndiscuss a number of nanotechnological systems that have been studied with\noxDNA, a recently developed coarse-grained model, highlighting the subtle\ninterplay of kinetic, thermodynamic and mechanical factors that can determine\nbehaviour. Finally, new results highlighting the importance of mechanical\ntension in the operation of a two-footed walker are presented, demonstrating\nthat recovery from an unintended `overstepped' configuration can be accelerated\nby three to four orders of magnitude by application of a moderate tension to\nthe walker's track. More generally, the walker illustrates the possibility of\nbiasing strand-displacement processes to affect the overall rate."
    },
    {
        "anchor": "Bending elasticity of a curved amphiphilic film decorated anchored\n  copolymers: a small angle neutron scattering study: Microemulsion droplets (oil in water stabilized by a surfactant film) are\nprogressively decorated with increasing amounts of poly ethylene- oxide (PEO)\nchains anchored in the film by the short aliphatic chain grafted at one end of\nthe PEO chain . The evolution of the bending elasticity of the surfactant film\nwith increasing decoration is deduced from the evolution in size and\npolydispersity of the droplets as reflected by small angle neutron scattering.\nThe optimum curvature radius decreases while the bending rigidity modulus\nremains practically constant. The experimental results compare well with the\npredictions of a model developed for the bending properties of a curved film\ndecorated by non-adsorbing polymer chains, which takes into account, the finite\ncurvature of the film and the free diffusion of the chains on the film.",
        "positive": "Dilational Viscosity of Langmuir monolayers: The dilational viscosity $\\epsilon'$ of Langmuir monolayer is considered in a\ntheoretical model taking into account an orientational effect of the dilational\nwave on surface molecules. This orientational order is described by the surface\norder parameter Q; the orientational part of the free surface energy is given\nby Landau's expansion in powers of Q. The magnitude of surface viscosity,\ndriven by the surface tension derivative $\\partial\\gamma/\\partial Q$, is in\ngood accord with the experimentally observed $\\epsilon'$. The sign of\n$\\epsilon'$ is positive that indicates that increased in-plane ordering\nincreases the surface tension."
    },
    {
        "anchor": "Control of colloidal placement by modulated molecular orientation in\n  nematic cells: Colloids self-assemble into various organized superstructures determined by\nparticle interactions. There is a tremendous progress in both the scientific\nunderstanding and applications of self-assemblies of single-type identical\nparticles. Forming superstructures in which the colloidal particles occupy\npredesigned sites and remain in these sites despite thermal fluctuations\nrepresents a major challenge of the current state-of-the art. Here we propose a\nversatile approach to direct placement of colloids using nematic liquid\ncrystals with spatially varying molecular orientation pre-imposed by substrate\nphotoalignment. Colloidal particles in nematic environment are subject to the\nlong-range elastic forces originating in the orientational order of the\nnematic. Gradients of the orientational order create an elastic energy\nlandscape that drives the colloids into locations with preferred type of\ndeformations. As an example, we demonstrate that colloidal spheres with\nperpendicular surface anchoring are driven into the regions of maximum splay,\nwhile spheres with tangential surface anchoring settle into the regions of\nbend. Elastic forces responsible for preferential placement are measured by\nexploring overdamped dynamics of the colloids. Control of colloidal\nself-assembly through patterned molecular orientation opens new opportunities\nfor design of materials and devices in which particles should be placed in\npre-designed locations.",
        "positive": "Determining the thickness and modulus of the nano-metric interphase\n  region using macroscopic modulus data in exfoliated polymer-clay\n  nanocomposites: This paper is an attempt to predict the thickness and modulus at the\nnanometric interphase region with the knowledge on the macroscopic Young's\nmodulus in the polymer-clay nanocomposites. First, a systematic design of 20160\nlinear elastic finite element simulations are used to derive an analytical\nequation between the interphase thickness, the interphase modulus, the nanoclay\ncontent and the macroscopic Young's modulus of the nanocomposite. Four\ncalibration parameters in this equation are calculated based on the reported\ndata about NYLON6-MMT nanocomposite. Next, an analytical nanoscale equation is\ndeveloped to satisfy the necessary boundary conditions at the nanometric\ninterphase. Finally, the interphase thickness and modulus are calculated by the\nintersection between the two equations. The validity of predictions are\nexamined using two distant data sets in literature. The predicted interphase\nthicknesses are consistent with the experimental reports which situate around\n2-8 nm in this nanocomposite. The presented approach can be used in design and\nprediction of mechanical properties in wide range of isotropic triple-phasic\nsystems with structural features similar to polymer clay nanocomposites."
    },
    {
        "anchor": "Wettability alteration in thiolene-based polymer microfluidics: surface\n  characterization and advanced fabrication techniques: Wettability plays a significant role in controlling multiphase flow in porous\nmedia for many industrial applications, including geologic carbon dioxide\nsequestration, enhanced oil recovery, and fuel cells. Microfluidics is a\npowerful tool to study the complexities of interfacial phenomena involved in\nmultiphase flow in well-controlled geometries. Recently, the thiolene-based\npolymer called NOA81 emerged as an ideal material in the fabrication of\nmicrofluidic devices, since it combines the versatility of conventional soft\nphotolithography with a wide range of achievable wettability conditions.\nSpecifically, the wettability of NOA81 can be continuously tuned through\nexposure to high-energy UV. Despite its growing popularity, the exact physical\nand chemical mechanisms behind the wettability alteration have not been fully\ncharacterized.\n  Here, we apply different characterization techniques, including contact angle\nmeasurements, X-ray photoelectron spectroscopy (XPS), and atomic force\nmicroscopy (AFM) to investigate the impact of high-energy UV on the chemical\nand physical properties of NOA81 surfaces. We find that high-energy UV exposure\nincreases the oxygen-containing polar functional groups, which enhances the\nsurface energy and hydrophilicity of NOA81. Additionally, our AFM measurements\nshow that spin-coated NOA81 surfaces have a roughness less than a nanometer,\nwhich is further reduced after high-energy UV irradiation. Lastly, we advance\nthe state-of-the-art of NOA81-based microfluidic systems by creating i) a 2D\nsurface with controlled wettability gradient and ii) a 3D column packed with\nmonodisperse NOA81 beads of controlled size and wettability.",
        "positive": "Twist dynamics and buckling instability of ring DNA: Effect of groove\n  asymmetry and anisotropic bending: By combining analytical theory and Molecular Dynamics simulations we study\nthe relaxation dynamics of DNA circular plasmids that initially undergo a local\ntwist perturbation. We identify three distinctive time scales; (I) a rapid\nrelaxation of local bending, (II) the slow twist spreading, and (III) the\nbuckling transition taking place in a much longer time scale. In all of these\nstages, the twist-bend coupling arising from the groove asymmetry in DNA double\nhelix clearly manifests. In particular, the separation of time scales allows to\ndeduce an effective diffusion equation in stage (II), with a diffusion\ncoefficient influenced by the twist-bend coupling. We also discuss the mapping\nof the realistic DNA model to the simplest isotropic twistable worm-like chain\nusing the renormalized bending and twist moduli; although useful in many cases,\nit fails to make a quantitative prediction on the instability mode of buckling\ntransition."
    },
    {
        "anchor": "Speeding up dynamics by tuning the non-commensurate size of rod-like\n  particles in a smectic phase: Using simulations, we study the diffusion of rod-like guest particles in a\nsmectic environment of rod-like host particles. We find that the dynamics of\nguest rods across smectic layers changes from a fast nematic-like diffusion to\na slow hopping-type dynamics via an intermediate switching regime by varying\nthe length of the guest rods with respect to the smectic layer spacing. We\ndetermine the optimal rod length that yields the fastest and the slowest\ndiffusion in a lamellar environment. We show that this behavior can be\nrationalized by a complex 1D effective periodic potential exhibiting two energy\nbarriers, resulting in a varying preferred mean position of the guest particle\nin the smectic layer. The interplay of these two barriers controls the dynamics\nof the guest particles yielding a slow, an intermediate and a fast diffusion\nregime depending on the particle length.",
        "positive": "Deformation of an Elastic Substrate Due to a Resting Sessile Droplet: On a sufficiently-soft substrate, a resting fluid droplet will cause\nsignificant deformation of the substrate. This deformation is driven by a\ncombination of capillary forces at the contact line and the fluid pressure at\nthe solid surface. These forces are balanced at the surface by the solid\ntraction stress induced by the substrate deformation. Young's Law, which\npredicts the equilibrium contact angle of the droplet, also indicates an a\npriori radial force balance for rigid substrates, but not necessarily for soft\nsubstrates which deform under loading. It remains an open question whether the\ncontact line transmits a non-zero radial force to the substrate surface in\naddition to the conventional vertical force. We present an analytic Fourier\ntransform solution technique that includes general interfacial energy\nconditions which govern the contact angle of a 2D droplet. This includes\nevaluating the effect of gravity on the droplet shape in order to determine the\ncorrect fluid pressure at the substrate surface for larger droplets.\nImportantly, we find that in order to avoid a strain singularity at the contact\nline under a nonzero radial contact line force, it is necessary to include a\npreviously-neglected radial traction boundary condition. To quantify the\neffects of the contact line and identify key quantities that will be\nexperimentally-accessible for testing the model, we evaluate solutions for the\nsubstrate surface displacement field as a function of Poisson's ratio and\nzero/non-zero radial contact line forces."
    },
    {
        "anchor": "Diffusiophoresis and medium structure control macroscopic particle\n  transport in porous media: In this letter, we show that pore-scale diffusiophoresis of colloidal\nparticles along local salt gradients manifests in the macroscopic dispersion of\nparticles in a porous medium. Despite is transient character, this microscopic\nphenomenon controls large-scale particle transport by altering their\npartitioning between transmitting and dead-end pores. It determines the\ndistribution of residence and arrival times in the medium. Depending on the\ndiffusiophoretic mobility, particles can be mobilized from or trapped in\ndead-end pores, which provides a means for the controlled manipulation of\nparticles in porous media.",
        "positive": "Deterministic Deposition of Nanoparticles with Sub-10 nm Resolution: Accurate deposition of nanoparticles at defined positions on a substrate is\nstill a challenging task, because it requires simultaneously stable long-range\ntransport and attraction to the target site and precise short-range orientation\nand deposition. Here we present a method based on geometry-induced energy\nlandscapes in a nanofluidic slit for particle manipulation: Brownian motors or\nelectro-osmotic flows are used for particle delivery to the target area. At the\ntarget site, electrostatic trapping localizes and orients the particles.\nFinally, reducing the gap distance of the slit leads sequentially to a focusing\nof the particle position and a jump into adhesive contact by several\nnanometers. For 60 nm gold spheres, we obtain a placement accuracy of 8 nm. The\nversatility of the method is demonstrated further by a stacked assembly of\nnanorods and the directed deposition of InAs nanowires."
    },
    {
        "anchor": "Gas-liquid critical point in ionic fluids: Based on the method of collective variables we develop the statistical field\ntheory for the study of a simple charge-asymmetric $1:z$ primitive model (SPM).\nIt is shown that the well-known approximations for the free energy, in\nparticular DHLL and ORPA, can be obtained within the framework of this theory.\nIn order to study the gas-liquid critical point of SPM we propose the method\nfor the calculation of chemical potential conjugate to the total number density\nwhich allows us to take into account the higher order fluctuation effects. As a\nresult, the gas-liquid phase diagrams are calculated for $z=2-4$. The results\ndemonstrate the qualitative agreement with MC simulation data: critical\ntemperature decreases when $z$ increases and critical density increases rapidly\nwith $z$.",
        "positive": "Effects of mechanical strain on thermal denaturation of DNA: As sections of a strand duplexed DNA denature when exposed to high\ntemperature, the excess linking number is taken up by the undenatured portions\nof the molecule. The mechanical energy that arises because of the overwinding\nof the undenatured sections can, in principle, alter the nature of the thermal\ndenaturation process. Assuming that the strains associated with this\noverwinding are not relieved, we find that a simple model of strain-altered\nmelting leads to a suppression of the melting transition when the unaltered\ntransition is continuous. When the melting transition is first order in the\nabsence of strain associated with overwinding, the modification is to a third\norder phase transition."
    },
    {
        "anchor": "Stopping and reversing sound via dynamic dispersion tuning in a phononic\n  metamaterial: Slowing down, stopping, and reversing a signal is a core functionality for\ninformation processing. Here, we show that this functionality can be realized\nby tuning the dispersion of a periodic system through a dispersionless, or\nflat, band. Specifically, we propose a phononic metamaterial based on plate\nresonators, in which the phonon band dispersion can be modified from an\nacoustic-like to an optical character by modulating a uniform prestress. The\nswitch is enabled by the change in sign of an effective coupling between\nfundamental modes, which generically leads to a nearly dispersion-free band at\nthe transition point. We demonstrate how adiabatic tuning of the band\ndispersion can immobilize and reverse the propagation of a sound pulse in\nsimulations of a one-dimensional resonator chain. Our study relies on the basic\nprinciples of thin-plate elasticity independently of any specific material,\nmaking our results applicable across varied length scales and experimental\nplatforms. More broadly, our approach could be metamaterials and electronic\nheterostructures.",
        "positive": "Stabilizing $\u03b1-$helicity of polypeptide in aqueous urea: Dipole\n  orientation or hydrogen bonding?: Urea denatures proteins due to its strong tendency to dehydrate the first\nsolvation shell via urea-residue preferential binding. However, even after\nextensive experimental and computational investigations, the influence of urea\non the stability of secondary structures remains elusive. For example, contrary\nto the common understanding, experimental studies have indicated that specific\npolypeptides, such as poly-alanine or alanine-rich systems, may even show an\nimproved tendency to form secondary structures in aqueous urea. We investigate\nthis seemingly counter-intuitive behaviour using over 15$\\mu$s long all-atom\nsimulations. These results show how a delicate balance between the localized\ndipole orientations and hydrogen bonding dictates polypeptide solvation in\naqueous urea. Our work establishes a structure-property relationship that\nhighlights the importance of microscopic dipole-dipole\norientations/interactions for the operational understanding of macroscopic\nprotein solvation."
    },
    {
        "anchor": "Pattern formation of skin cancers: Effects of cancer proliferation and\n  hydrodynamic interactions: We study pattern formation of skin cancers by means of numerical simulation\nof a binary system consisting of cancer and healthy cells. We extend the\nconventional Model H for macrophase separations by considering a logistic\ngrowth of cancer cells and also a mechanical friction between dermis and\nepidermis. Importantly, our model exhibits a microphase separation due to the\nproliferation of cancer cells. By numerically solving the time evolution\nequations of the cancer composition and its velocity, we show that the phase\nseparation kinetics strongly depends on the cell proliferation rate as well as\non the strength of hydrodynamic interactions. A steady state diagram of cancer\npatterns is established in terms of these two dynamical parameters and some of\nthe patterns correspond to clinically observed cancer patterns. Furthermore, we\nexamine in detail the time evolution of the average composition of cancer cells\nand the characteristic length of the microstructures. Our results demonstrate\nthat different sequence of cancer patterns can be obtained by changing the\nproliferation rate and/or hydrodynamic interactions.",
        "positive": "Polymer chains in confined geometries: Massive field theory approach: The massive field theory approach in fixed space dimensions $d=3$ is applied\nto investigate a dilute solution of long-flexible polymer chains in a good\nsolvent between two parallel repulsive walls, two inert walls and for the mixed\ncase of one inert and one repulsive wall. The well known correspondence between\nthe field theoretical $\\phi^4$ O(n)-vector model in the limit $n\\to 0$ and the\nbehavior of long-flexible polymer chains in a good solvent is used to calculate\nthe depletion interaction potential and the depletion force up to one-loop\norder. Our investigations include modification of renormalization scheme for\nthe case of two inert walls. The obtained results confirm that the depletion\ninteraction potential and the resulting depletion force between two repulsive\nwalls are weaker for chains with excluded volume interaction (EVI) than for\nideal chains, because the EVI effectively reduces the depletion effect near the\nwalls. Our results are in qualitative agreement with previous theoretical\ninvestigations, experimental results and with results of Monte Carlo\nsimulations."
    },
    {
        "anchor": "A Particle-Water Based Model for Water Retention Hysteresis: A particle-water discrete element based approach to describe water movement\nin partially saturated granular media is presented and tested. Water potential\nis governed by both capillary bridges, dominant at low saturations, and the\npressure of entrapped air, dominant at high saturations. The approach captures\nthe hysteresis of water retention during wetting and drainage by introducing\nthe local evolution of liquid-solid contact angles at the level of pores and\ngrains. Extensive comparisons against experimental data are presented. While\nthese are made without the involvement of any fitting parameters, the method\ndemonstrates relative high success by achieving a correlation coefficient of at\nleast 82%, and mostly above 90%. For the tested materials with relatively\nmono-disperse grain size, the hysteresis of water retention during cycles of\nwetting and drainage has been shown to arise from the dynamics of solid-liquid\ncontact angles as a function of local liquid volume changes.",
        "positive": "Non-mean-field theory of anomalously large double-layer capacitance: Mean-field theories claim that the capacitance of the double-layer formed at\na metal/ionic conductor interface cannot be larger than that of the Helmholtz\ncapacitor, whose width is equal to the radius of an ion. However, in some\nexperiments the apparent width of the double-layer capacitor is substantially\nsmaller. We propose an alternate, non-mean-field theory of the ionic\ndouble-layer to explain such large capacitance values. Our theory allows for\nthe binding of discrete ions to their image charges in the metal, which results\nin the formation of interface dipoles. We focus primarily on the case where\nonly small cations are mobile and other ions form an oppositely-charged\nbackground. In this case, at small temperature and zero applied voltage dipoles\nform a correlated liquid on both contacts. We show that at small voltages the\ncapacitance of the double-layer is determined by the transfer of dipoles from\none electrode to the other and is therefore limited only by the weak\ndipole-dipole repulsion between bound ions, so that the capacitance is very\nlarge. At large voltages the depletion of bound ions from one of the capacitor\nelectrodes triggers a collapse of the capacitance to the much smaller\nmean-field value, as seen in experimental data. We test our analytical\npredictions with a Monte Carlo simulation and find good agreement. We further\nargue that our ``one-component plasma\" model should work well for strongly\nasymmetric ion liquids. We believe that this work also suggests an improved\ntheory of pseudo-capacitance."
    },
    {
        "anchor": "Evolution of a coherent array of Bose-Einstein Condensates in a magnetic\n  trap: We investigate the evolution process of the interference pattern for a\ncoherent array of Bose-Einstein condensates in a magnetic trap after the\noptical lattices are switched off. It is shown that there is a decay and\nrevival of the density oscillation for the condensates confined in the magnetic\ntrap. We find that, due to the confinement of the magnetic trap, the\ninterference effect is much stronger than that of the experiment induced by\nPedri et al. (Phys. Rev. Lett, {\\bf 87}, 220401), where the magnetic trap is\nswitched off too. The interaction correction to the interference effect is also\ndiscussed for the density distribution of the central peak.",
        "positive": "Nonlinear waves in double-stranded DNA: We propose a nonlinear model derived from first principles, to describe\nbubble dynamics of DNA. Our model equations include a term derived from the\ndissipative effect of intermolecular vibrational modes. Such modes are excited\nby the propagating bubble, and we term it \"curvature dissipation\". The\nequations we derive allow for stable pinned localized kinks which form the\nbubble. We perform the stability analysis and specify the energy requirements\nfor the motion of the localized solutions. Our findings are consistent with\nproperties of DNA dynamics, and can be used in models for denaturation bubbles,\nRNA and DNA transcription, nucleotide excision repair and meiotic\nrecombination."
    },
    {
        "anchor": "Active matter, microreversibility, and thermodynamics: Active matter, comprising many active agents interacting and moving in fluids\nor more complex environments, is a commonly occurring state of matter in\nbiological and physical systems. By its very nature active matter systems exist\nin nonequilibrium states. In this paper the active agents are small Janus\ncolloidal particles that use chemical energy provided by chemical reactions\noccurring on their surfaces for propulsion through a diffusiophoretic\nmechanism. As a result of interactions among these colloids, either directly or\nthrough fluid velocity and concentration fields, they may act collectively to\nform structures such as dynamic clusters. A general nonequilibrium\nthermodynamics framework for the description of such systems is presented that\naccounts for both self-diffusiophoresis and diffusiophoresis due to external\nconcentration gradients, and is consistent with microreversibility. It predicts\nthe existence of a reciprocal effect of diffusiophoresis back onto the reaction\nrate for the entire collection of colloids in the system, as well as the\nexistence of a clustering instability that leads to nonequilibrium\ninhomogeneous system states.",
        "positive": "Statistics of bubble rearrangement dynamics in a coarsening foam: We use speckle-visibility spectroscopy to measure the time-dependence of\nbubble rearrangement events that are driven by coarsening in an aqueous foam.\nThis technique gives the time-trace for the average scattering site speed\nwithin a prescribed volume of the sample. Results are analyzed in terms of\ndistributions of event times, event speeds, and event displacements. The\ndistribution of rest times between successive events is also measured;\ncomparison with diffusing-wave spectroscopy results shows that the spatial\nstructure of a typical event consists of a core of only a few bubbles which\nundergo topology change plus a surrounding halo of bubbles which shift by an\namount that decays to one wavelength at four to five bubbles away. No\ncorrelations are found between the durations, speeds, and rest times between\nsuccessive events."
    },
    {
        "anchor": "Pressure sensitivity in non-local flow behaviour of dense hydrogel\n  particle suspensions: Slowly sheared particulate media like sand and suspensions flow\nheterogeneously as they yield via narrow shear bands where most of the strain\nis accumulated. Understanding shear band localization from microscopics is\nstill a major challenge. One class of so-called non-local theories identified\nthat the width of the shearing zone should depend on the stress field. We\nexplicitly test this picture by using a uniquely stress-sensitive suspension\nwhile probing its flow behavior in a classic geometry in which shear bands can\nbe well-tuned: the Split-Bottom Shear Cell (SBSC). The stress-sensitive\nsuspension is composed of mildly polydisperse soft, slippery hydrogel spheres\nsubmersed in water. We measure their flow profiles and rheology while\ncontrolling the confinement stress via hydrostatic effects and compression. We\ndetermine the average angular velocity profiles in the quasi-static flow regime\nusing Magnetic Resonance Imaging based particle image velocimetry (MRI-PIV) and\ndiscrete element method (DEM) simulations. We explicitly match a\npressure-sensitive non-local granular fluidity (NGF) model to observed flow\nbehavior. We find that shear bands for this type of suspension become extremely\nbroad under the low confining stresses from the almost density-matched fluid\nparticle mixture, while collapsing to a narrow shear zone under finite,\nexternally imposed compression levels. The DEM and NGF results match the\nobservations quantitatively, confirming the conjectured pressure sensitivity\nfor suspensions and its role in NGF. Our results indicate that pressure\nsensitivity should be part of non-local flow rules to describe slow flows of\ngranular media.",
        "positive": "Synchrotron-based UV resonance Raman scattering for investigating ionic\n  liquid-water solutions: This work shows that bulk ionic liquids (ILs) and their water solution can be\nconveniently investigated by synchrotron-based UV resonance Raman (UVRR)\nspectroscopy. The main advantages of this technique for the investigation of\nthe local structure and intermolecular interactions in imidazolium-based ILs\nare presented and discussed. The unique tunability of synchrotron source allows\none to selectively enhance in the Raman spectra the vibrational signals arising\nfrom the imidazolium ring. Such signals showed good sensitivity to the\nmodifications induced in the local structure of ILs by i) the change of anion\nand ii) the progressively longer alkyl chain substitution on the imidazolium\nring. Moreover, some UVRR signals are specifically informative on the effect\ninduced by addition of water on the strength of cation-anion H-bonds in\nIL-water solutions. All of these results corroborate the potentiality of UVRR\nto retrieve information on the intermolecular interactions in IL-water\nsolutions, besides the counterpart obtained by employing on these systems the\nspontaneous Raman scattering technique."
    },
    {
        "anchor": "A Study of Sequence Distribution of a Painted Globule as a Model for\n  Proteins with Good Folding Properties: In this paper we present a method to study the folding structure of a simple\nmodel consisting of two kinds of monomers, hydrophobic and hydrophilic. This\nmethod has three main steps: an efficient simulation method to bring an open\nsequence of homopolymer to a folded state, the application of a painting method\ncalled (regular hull) to the folded globule and the refolding process of the\nobtained copolymer sequence. This study allows us to suggest a theoretical\nfunction of disorder distribution for copolymer sequences that give rise to a\ncompacted and well micro-phase separated globule.",
        "positive": "Element- and enantiomer-selective visualization of ibuprofen dimer\n  vibrations: In chemistry, biology and materials science, the ability to access\ninteratomic interactions and their dynamical evolution has become possible with\nthe advent of femtosecond lasers. In particular, the observation of vibrational\nwave packets via optical (UV-visible-IR) spectroscopies has been a major\nachievement as it can track the motion of nuclei within the system. However,\noptical spectroscopies only detect the effect of the interatomic vibrations on\nthe global electronic surfaces. New tuneable, pulsed and polarized sources of\nshort-wavelength radiation, such as X-Ray Free electron lasers, can overcome\nthis limitation, allowing for chemical and, of primary importance in\nbiochemistry, enantiomeric selectivity. This selectivity may be complemented by\ntaking into account the chemical shifts of atoms belonging to different\nmolecular moieties"
    },
    {
        "anchor": "Equilibrium and dynamic pleating of a crystalline bonded network: We describe a phase transition that gives rise to structurally non-trivial\nstates in a two-dimensional ordered network of particles connected by harmonic\nbonds. Monte Carlo simulations reveal that the network supports, apart from the\nhomogeneous phase, a number of heterogeneous \"pleated\" phases, which can be\nstabilised by an external field. This field is conjugate to a global collective\nvariable quantifying \"non-affineness\", i.e.~the deviation of local particle\ndisplacements from local affine deformation. In the pleated phase, stress is\nlocalised in ordered rows of pleats and eliminated from the rest of the\nlattice. The {\\em kinetics} of the phase transition is unobservably slow in\nmolecular dynamics simulation near coexistence, due to very large free energy\nbarriers. When the external field is increased further to lower these barriers,\nthe network exhibits rich dynamic behaviour: it transforms into a {\\em\nmetastable} phase with the stress now localised in a {\\em disordered}\narrangement of pleats. The pattern of pleats shows ageing dynamics and slow\nrelaxation to equilibrium. Our predictions may be checked by experiments on\ntethered colloidal solids in dynamic laser traps.",
        "positive": "Tube width fluctuations of entangled stiff polymers: The tube-like cages of stiff polymers in entangled solutions have been shown\nto exhibit characteristic spatial heterogeneities. We explain these\nobservations by a systematic theory generalizing previous work by D. Morse\n(Phys. Rev. E 63:031502, 2001). With a local version of the binary collision\napproximation (BCA), the distribution of confinement strengths is calculated,\nand the magnitude and the distribution function of tube radius fluctuations are\npredicted. Our main result is a unique scaling function for the tube radius\ndistribution, in good agreement with experimental and simulation data."
    },
    {
        "anchor": "Lattice Boltzmann Approach to High-Speed Compressible Flows: We present an improved lattice Boltzmann model for high-speed compressible\nflows. The model is composed of a discrete-velocity model by Kataoka and\nTsutahara [Phys. Rev. E \\textbf{69}, 056702 (2004)] and an appropriate\nfinite-difference scheme combined with an additional dissipation term. With the\ndissipation term parameters in the model can be flexibly chosen so that the von\nNeumann stability condition is satisfied. The influence of the various model\nparameters on the numerical stability is analyzed and some reference values of\nparameter are suggested. The new scheme works for both subsonic and supersonic\nflows with a Mach number up to 30 (or higher), which is validated by well-known\nbenchmark tests. Simulations on Riemann problems with very high ratios\n($1000:1$) of pressure and density also show good accuracy and stability.\nSuccessful recovering of regular and double Mach shock reflections shows the\npotential application of the lattice Boltzmann model to fluid systems where\nnon-equilibrium processes are intrinsic. The new scheme for stability can be\neasily extended to other lattice Boltzmann models.",
        "positive": "Coiling Instability of Multilamellar Membrane Tubes with Anchored\n  Polymers: We study experimentally a coiling instability of cylindrical multilamellar\nstacks of phospholipid membranes, induced by polymers with hydrophobic anchors\ngrafted along their hydrophilic backbone. Our system is unique in that coils\nform in the absence of both twist and adhesion. We interpret our experimental\nresults in terms of a model in which local membrane curvature and polymer\nconcentration are coupled. The model predicts the occurrence of maximally tight\ncoils above a threshold polymer occupancy. A proper comparison between the\nmodel and experiment involved imaging of projections from simulated coiled\ntubes with maximal curvature and complicated torsions."
    },
    {
        "anchor": "Development of a confocal rheometer for soft and biological materials: We discuss the design and operation of a confocal rheometer, formed by\nintegrating an Anton Paar MCR301 stress-controlled rheometer with a Leica SP5\nlaser scanning confocal microscope. Combining two commercial instruments\nresults in a system which is straightforward to assemble that preserves the\nperformance of each component with virtually no impact on the precision of\neither device. The instruments are configured so that the microscope can\nacquire time-resolved, three-dimensional volumes of a sample whose bulk\nviscoelastic properties are being measured simultaneously. We describe several\naspects of the design and, to demonstrate the system's capabilities, present\nthe results of a few common measurements in the study of soft materials.",
        "positive": "Discontinuous change from thermally- to geometrically- dominated\n  effective interactions in colloidal solutions: We report numerical results for the effective potential arising between two\ncolloids immersed in a self-assembling cosolute which forms reversible\nclusters. The potential is evaluated at cosolute state points with different\ndensities and temperatures but with the same connectivity properties. We find\nthat the range of the resulting effective potential is controlled only by the\ncosolute thermal correlation length rather than by its connectivity length. We\ndiscuss the significant differences with previous results focused on cosolute\nforming irreversible clusters and we show that irreversible bond case\nrepresents a singular limit which cannot be accessed in equilibrium by\ncontinuously increasing the bond lifetime."
    },
    {
        "anchor": "Impurity in a granular gas under nonlinear Couette flow: We study in this work the transport properties of an impurity immersed in a\ngranular gas under stationary nonlinear Couette flow. The starting point is a\nkinetic model for low-density granular mixtures recently proposed by the\nauthors [Vega Reyes F et al. 2007 Phys. Rev. E 75 061306]. Two routes have been\nconsidered. First, a hydrodynamic or normal solution is found by exploiting a\nformal mapping between the kinetic equations for the gas particles and for the\nimpurity. We show that the transport properties of the impurity are\ncharacterized by the ratio between the temperatures of the impurity and gas\nparticles and by five generalized transport coefficients: three related to the\nmomentum flux (a nonlinear shear viscosity and two normal stress differences)\nand two related to the heat flux (a nonlinear thermal conductivity and a cross\ncoefficient measuring a component of the heat flux orthogonal to the thermal\ngradient). Second, by means of a Monte Carlo simulation method we numerically\nsolve the kinetic equations and show that our hydrodynamic solution is valid in\nthe bulk of the fluid when realistic boundary conditions are used. Furthermore,\nthe hydrodynamic solution applies to arbitrarily (inside the continuum regime)\nlarge values of the shear rate, of the inelasticity, and of the rest of\nparameters of the system. Preliminary simulation results of the true Boltzmann\ndescription show the reliability of the nonlinear hydrodynamic solution of the\nkinetic model. This shows again the validity of a hydrodynamic description for\ngranular flows, even under extreme conditions, beyond the Navier-Stokes domain.",
        "positive": "Dynamics of membranes with immobile inclusions: Cell membranes are anchored to the cytoskeleton via immobile inclusions. We\ninvestigate the effect of such anchors on the in-plane dynamics of a fluid\nmembrane and mobile inclusions (proteins) embedded in it. The immobile\nparticles lead to a decreased diffusion coefficient of mobile ones and suppress\nthe correlated diffusion of particle pairs. Due to the long-range,\nquasi-two-dimensional nature of membrane flows, these effects become\nsignificant at a low area fraction (below one percent) of immobile inclusions."
    },
    {
        "anchor": "Comparative analysis of machine learning models for Ammonia Capture of\n  Ionic Liquids: Industry uses various solvents in the processes of refrigeration and\nventilation. Among them, the Ionic liquids (ILs) as the relatively new\nsolvents, are known for their proven eco-friendly characteristics. In this\nresearch, a comprehensive literature review was carried out to deliver an\ninsight into the ILs and the prediction models used for estimating the ammonia\nsolubility in ILs. Furthermore, a number of advanced machine learning methods,\ni.e. multilayer perceptron (MLP) and a combination of particle swarm\noptimization (PSO) and adaptive neuro-fuzzy inference system (ANFIS) models are\nused to estimate the solubility of ammonia in various ionic liquids. Affecting\nparameters were molecular weight, critical temperature and pressure of ILs.\nFurthermore, the salability is also predicted using the two-equation of states.\nDown the line, some comparisons were drawn between experimental and modeling\nresults which is rarely done. The study shows that the equations of states are\nnot able estimate the solubility of ammonia accurately, by contrast, artificial\nintelligence methods have produced promising results.",
        "positive": "Kinetic Theory and Memory Effects of Homogeneous Inelastic Granular\n  Gases under Nonlinear Drag: We study a dilute granular gas immersed in a thermal bath made of smaller\nparticles with masses not much smaller than the granular ones in this work.\nGranular particles are assumed to have inelastic and hard interactions, losing\nenergy in collisions as accounted by a constant coefficient of normal\nrestitution. The interaction with the thermal bath is modeled by a nonlinear\ndrag force plus a white-noise stochastic force. The kinetic theory for this\nsystem is described by an Enskog--Fokker--Planck equation for the one-particle\nvelocity distribution function. To get explicit results of the temperature\naging and steady states, Maxwellian and first Sonine approximations are\ndeveloped. The latter takes into account the coupling of the excess kurtosis\nwith the temperature. Theoretical predictions are compared with direct\nsimulation Monte Carlo and event-driven molecular dynamics simulations. While\ngood results for the granular temperature are obtained from the Maxwellian\napproximation, a much better agreement, especially as inelasticity and drag\nnonlinearity increase, is found when using the first Sonine approximation. The\nlatter approximation is, additionally, crucial to account for memory effects\nsuch as Mpemba and Kovacs-like ones."
    },
    {
        "anchor": "Lattice cluster theory for polymer melts with specific interactions: Despite the long-recognized fact that chemical structure and specific\ninteractions greatly influence the thermodynamic properties of polymer systems,\na predictive molecular theory that enables systematically addressing the role\nof chemical structure and specific interactions has been slow to develop even\nfor polymer melts. While the lattice cluster theory (LCT) provides a powerful\nvehicle for understanding the influence of various molecular factors, such as\nmonomer structure, on the thermodynamic properties of polymer melts and blends,\nthe application of the LCT has heretofore been limited to the use of the\nsimplest polymer model in which all united atom groups within the monomers of a\nspecies interact with a common monomer averaged van der Waals energy. Thus, the\ndescription of a compressible polymer melt involves a single van der Waals\nenergy. As a first step towards developing more realistic descriptions to aid\nin the analysis of experimental data and the design of new materials, the LCT\nis extended here to treat models of polymer melts in which the backbone and\nside groups have different interaction strengths, so three energy parameters\nare present, namely, backbone-backbone, side group-side group, and\nbackbone-side group interaction energies. Because of the great algebraic\ncomplexity of this extension, we retain maximal simplicity within this class of\nmodels by further specializing this initial study to models of polymer melts\ncomprising chains with poly($n$-$\\alpha$-olefin) structures where only the end\nsegments on the side chains may have different, specific van der Waals\ninteraction energies with the other united atom groups. An analytical\nexpression for the LCT Helmholtz free energy is derived for the new model.\nIllustrative calculations are presented to demonstrate the degree to which the\nthermodynamic properties of polymer melts can be controlled by specific\ninteractions.",
        "positive": "Sliding Columnar Phase of DNA-Lipid Complexes: We introduce a simple model for DNA-cationic-lipid complexes in which\ngalleries between planar bilayer lipid lamellae contain DNA 2D smectic lattices\nthat couple orientationally and positionally to lattices in neighboring\ngalleries. We identify a new equilibrium phase in which there are long-range\norientational but not positional correlations between DNA lattices. We discuss\nproperties of this new phase such as its X-ray structure factor S(r), which\nexhibits unusual exp(- const.ln^2 r) behavior as a function of in-plane\nseparation r."
    },
    {
        "anchor": "Physical Questions Posed by DNA Condensation: When multivalent salts are added to dilute DNA solution, the DNA chains\ncondense into bundles of a well-defined size. We explore two physical problems\nmotivated by this phenomenon: the origin of the attractive interactions between\nthe highly-negatively charged DNA chains that cause them to concentrate into\nbundles, and the mechanism that provents the bundles from growing indefinitely\nlarge.",
        "positive": "Work probability distribution in single molecule experiments: We derive and solve a differential equation satisfied by the probability\ndistribution of the work done on a single biomolecule in a mechanical unzipping\nexperiment. The unzipping is described as a thermally activated escape process\nin an energy landscape. The Jarzynski equality is recovered as an identity,\nindependent of the pulling protocol. This approach allows one to evaluate\neasily, by numerical integration, the work distribution, once a few parameters\nof the energy landscape are known."
    },
    {
        "anchor": "Bijels Containing Magnetic Particles: A Simulation Study: Bicontinuous, interfacially jammed emulsion gels (bijels) represent a class\nof soft solid materials in which interpenetrating domains of two immiscible\nfluids are stabilized by an interfacial colloidal monolayer. Such structures\ncan be formed by arrested spinodal decomposition from an initially single-phase\ncolloidal suspension. Here we explore by lattice Boltzmann simulation the\npossible effects of using magnetic colloids in bijels. This may allow\nadditional control over the structure, during or after formation, by\napplication of a magnetic field or field gradient. These effects are modest for\ntypical parameters based on the magnetic nanoparticles used in conventional\nferrofluids, although significantly larger particles might be appropriate here.\nField gradient effects, which are cumulative across a sample, could then allow\na route for controlled breakdown of bijels as they do for particle-stabilized\ndroplet emulsions.",
        "positive": "Low-speed impact craters in loose granular media: We report on craters formed by balls dropped into dry, non-cohesive, granular\nmedia. By explicit variation of ball density $\\rho_{b}$, diameter $D_{b}$, and\ndrop height $H$, the crater diameter is confirmed to scale as the 1/4 power of\nthe energy of the ball at impact:\n  $D_{c}\\sim(\\rho_{b}{D_{b}}^{3}H)^{1/4}$. Against expectation, a different\nscaling law is discovered for the crater depth:\n  $d\\sim({\\rho_{b}}^{3/2}{D_{b}}^{2}H)^{1/3}$. The scaling with properties of\nthe medium is also established. The crater depth has significance for granular\nmechanics in that it relates to the stopping force on the ball."
    },
    {
        "anchor": "Kinetic roughening of aggregates of patchy colloids with strong and weak\n  bonds: We study the irreversible aggregation of films of patchy spherical colloids\nwith directional and selective interactions. We report a crossover of the\ninterfacial roughening from the Kardar-Parisi-Zhang (KPZ) to the KPZ with\nquenched disorder (KPZQ) universality class when the difference between the\nstrong and weak bonds is sufficiently large. We calculate the critical\nexponents and identify the crossover between the two regimes.",
        "positive": "Orientation-dependent propulsion of active Brownian spheres: from\n  self-advection to programmable cluster shapes: Applications of active particles require a method for controlling their\ndynamics. While this is typically achieved via direct interventions, indirect\ninterventions based, e.g., on an orientation-dependent self-propulsion speed of\nthe particles, become increasingly popular. In this work, we investigate\nsystems of interacting active Brownian spheres in two spatial dimensions with\norientation-dependent propulsion using analytical modeling and Brownian\ndynamics simulations. It is found that the orientation-dependence leads to\nself-advection, circulating currents, and programmable cluster shapes."
    },
    {
        "anchor": "A comprehensive framework for hard-magnetic beams: reduced-order theory,\n  3D simulations, and experiments: Thin beams made of magnetorheological elastomers embedded with hard magnetic\nparticles (hard-MREs) are capable of large deflections under an applied\nmagnetic field. We propose a comprehensive framework, comprising a beam model\nand 3D finite element modeling (FEM), to describe the behavior of hard-MRE\nbeams under both uniform and constant gradient magnetic fields. First, based on\nthe Helmholtz free energy of bulk (3D) hard-MREs, we perform dimensional\nreduction to derive a 1D description and obtain the equilibrium equation of the\nbeam through variational methods. In parallel, we extend the existing 3D\ncontinuum theory for hard-MREs to the general case of non-uniform fields by\nincorporating the magnetic body force induced by the field gradient and\nimplementing it in FEM. The beam model and FEM are first validated using\nexperiments and then employed to predict the deflection of a cantilever beam in\neither a uniform or a constant gradient field. The corresponding parameters\ngoverning the magneto-elastic coupling are identified. Then, a set of\ncomparative numerical studies for actuation in different configurations yields\nadditional insight into the beam response. Our study builds on previous work on\nhard-MRE beams, while providing a more complete framework, both in terms of the\nmethodologies used and the configurations considered, to serve as a valuable\npredictive toolbox for the rational design of beam-like hard-magnetic\nstructures.",
        "positive": "Polyelectrolyte multilayer formation: electrostatics and short-range\n  interactions: We investigate the phenomenon of multilayer formation via layer-by-layer\ndeposition of alternating charge polyelectrolytes. Using mean-field theory, we\nfind that a strong short-range attraction between the two types of polymer\nchains is essential for the formation of multilayers. The dependence of the\nrequired short-range attraction on the polymer charge fraction and salt\nconcentration is calculated. For weak short-range attraction between any two\nadjacent layers, the adsorbed amount (per added layer) decays as the distance\nfrom the surface increases, until the chains stop adsorbing altogether. For\nstrong short-range attraction, the adsorbed amount per layer increases after an\ninitial decrease, and finally it stabilizes in the form of a polyelectrolyte\nmultilayer that can be repeated many times."
    },
    {
        "anchor": "Complexation of DNA with positive spheres: phase diagram of charge\n  inversion and reentrant condensation: The phase diagram of a water solution of DNA and oppositely charged spherical\nmacroions is studied. DNA winds around spheres to form beads-on-a-string\ncomplexes resembling the chromatin 10 nm fiber. At small enough concentration\nof spheres these \"artificial chromatin\" complexes are negative, while at large\nenough concentrations of spheres the charge of DNA is inverted by the adsorbed\nspheres. Charges of complexes stabilize their solutions. In the plane of\nconcentrations of DNA and spheres the phases with positive and negative\ncomplexes are separated by another phase, which contains the condensate of\nneutral DNA-spheres complexes. Thus when the concentration of spheres grows,\nDNA-spheres complexes experience condensation and resolubilization (or\nreentrant condensation). Phenomenological theory of the phase diagram of\nreentrant condensation and charge inversion is suggested. Parameters of this\ntheory are calculated by microscopic theory. It is shown that an important part\nof the effect of a monovalent salt on the phase diagram can be described by the\nnontrivial renormalization of the effective linear charge density of DNA wound\naround a sphere, due to the Onsager-Manning condensation. We argue that our\nphenomenological phase diagram or reentrant condensation is generic to a large\nclass of strongly asymmetric electrolytes. Possible implication of these\nresults for the natural chromatin are discussed.",
        "positive": "Electrostatic effect due to patch potentials between closely spaced\n  surfaces: The spatial variation and temporal variation in surface potential are\nimportant error sources in various precision experiments and deserved to be\nconsidered carefully. In the former case, the theoretical analysis shows that\nthis effect depends on the surface potentials through their spatial\nautocorrelation functions. By making some modification to the quasi-local\ncorrelation model, we obtain a rigorous formula for the patch force, where the\nmagnitude is proportional to ${\\frac{1}{{{a}^{2}}}{{(\\frac{a}{w})}^{\\beta\n(a/w)+2}}}$ with ${a}$ the distance between two parallel plates, ${w}$ the mean\npatch size, and ${\\beta}$ the scaling coefficient from ${-2}$ to ${-4}$. A\ntorsion balance experiment is then conducted, and obtain a 0.4 mm effective\npatch size and 20 mV potential variance. In the latter case, we apply an adatom\ndiffusion model to describe this mechanism and predicts a ${f^{-3/4}}$\nfrequency dependence above 0.01 ${\\rm mHz}$. This prediction meets well with a\ntypical experimental results. Finally, we apply these models to analyze the\npatch effect for two typical experiments. Our analysis will help to investigate\nthe properties of surface potentials."
    },
    {
        "anchor": "A fractal approach to the rheology of concentrated cell suspensions: Results on the rheological behavior of novel CHO cell suspensions in a large\nrange of concentrations are reported. The concentration dependent yield stress\nand elastic plateau modulus are formalized in the context of fractal aggregates\nunder shear, and quite different exponents are found as compared to the case of\nred blood cell suspensions. This is explained in terms of intrinsic microscopic\nparameters such as the cell-cell adhesion energy and cell elasticity but also\nthe cell individual dynamic properties, found to correlate well with\nviscoelastic data at large concentrations (phi>0.5).",
        "positive": "Contact theorems for anisotropic fluids near a hard wall: In this paper, starting from the Born-Green-Yvon (BGY) equation, we derive a\ngeneral expression for the contact value of the singlet distribution function\nnear a hard wall for anisotropic fluids. This relation includes two separate\ncontributions. One is connected to the partial bulk pressure relative to a\ngiven orientation of the molecules. The second one is connected to the\nanchoring phenomena and is characterized by the direct interaction between the\nmolecules and the wall. From this relation, we then formulate the contact\ntheorem for the density and the order parameter profiles. The results are\nillustrated on the case of a nematic fluid near a hard wall."
    },
    {
        "anchor": "Confocal microscopy of colloidal particles: towards reliable, optimum\n  coordinates: Over the last decade, the light microscope has become increasingly useful as\na quantitative tool for studying colloidal systems. The ability to obtain\nparticle coordinates in bulk samples from micrographs is particularly\nappealing. In this paper we review and extend methods for optimal image\nformation of colloidal samples, which is vital for particle coordinates of the\nhighest accuracy, and for extracting the most reliable coordinates from these\nimages. We discuss in depth the accuracy of the coordinates, which is sensitive\nto the details of the colloidal system and the imaging system. Moreover, this\naccuracy can vary between particles, particularly in dense systems. We\nintroduce a previously unreported error estimate and use it to develop an\niterative method for finding particle coordinates. This individual-particle\naccuracy assessment also allows comparison between particle locations obtained\nfrom different experiments. Though aimed primarily at confocal microscopy\nstudies of colloidal systems, the methods outlined here should transfer readily\nto many other feature extraction problems, especially where features may\noverlap one another.",
        "positive": "Dipolar Poisson-Boltzmann Approach to Ionic Solutions: A Mean Field and\n  Loop Expansion Analysis: We study the variation of the dielectric response of ionic aqueous solutions\nas function of their ionic strength. The effect of salt on the dielectric\nconstant appears through the coupling between ions and dipolar water molecules.\nOn a mean-field level, we account for any internal charge distribution of\nparticles. The dipolar degrees of freedom are added to the ionic ones and\nresult in a generalization of the Poisson-Boltzmann (PB) equation called the\nDipolar PB (DPB). By looking at the DPB equation around a fixed point-like ion,\na closed-form formula for the dielectric constant is obtained. We express the\ndielectric constant using the \"hydration length\" that characterizes the\nhydration shell of dipoles around ions, and thus the strength of the dielectric\ndecrement. The DPB equation is then examined for three additional cases:\nmixture of solvents, polarizable medium and ions of finite size. Employing\nfield-theoretical methods we expand the Gibbs free-energy to first order in a\nloop expansion and calculate self-consistently the dielectric constant. For\npure water, the dipolar fluctuations represent an important correction to the\nmean-field value and good agreement with the water dielectric constant is\nobtained. For ionic solutions we predict analytically the dielectric decrement\nthat depends on the ionic strength in a non-linear way. Our prediction fits\nrather well a large range of concentrations for different salts using only one\nfit parameter related to the size of ions and dipoles. A linear dependence of\nthe dielectric constant on the salt concentration is observed at low salinity,\nand a noticeable deviation from linearity can be seen for ionic strength above\n1\\,M, in agreement with experiments."
    },
    {
        "anchor": "Measurement of correlations between low-frequency vibrational modes and\n  particle rearrangements in quasi-two-dimensional colloidal glasses: We investigate correlations between low-frequency vibrational modes and\nrearrangements in two-dimensional colloidal glasses composed of thermosensitive\nmicrogel particles which readily permit variation of sample packing fraction.\nAt each packing fraction, the particle displacement covariance matrix is\nmeasured and used to extract the vibrational spectrum of the \"shadow\" colloidal\nglass (i.e., the particle network with the same geometry and interactions as\nthe sample colloid but absent damping). Rearrangements are induced by\nsuccessive, small reductions in packing fraction. The experimental results\nsuggest that low-frequency quasi-localized phonon modes in colloidal glasses,\ni.e., modes that present low energy barriers for system rearrangements, are\nspatially correlated with rearrangements in this thermal system.",
        "positive": "Sculpting liquids with ultrathin shells: Thin elastic films can spontaneously attach to liquid interfaces, offering a\nplatform for tailoring their physical, chemical, and optical properties.\nCurrent understanding of the elastocapillarity of thin films is based primarily\non studies of planar sheets. We show that curved shells can be used to\nmanipulate interfaces in qualitatively different ways. We elucidate a regime\nwhere an ultrathin shell with vanishing bending rigidity imposes its own rest\nshape on a liquid surface, using experiment and theory. Conceptually, the\npressure across the interface \"inflates\" the shell into its original shape. The\nsetup is amenable to optical applications as the shell is transparent, free of\nwrinkles, and may be manufactured over a range of curvatures."
    },
    {
        "anchor": "Non-equilibrium steady states of electrolyte interfaces: The non-equilibrium steady states of a semi-infinite quasi-one-dimensional\nunivalent binary electrolyte solution, characterised by non-vanishing electric\ncurrents, are investigated by means of Poisson-Nernst-Planck (PNP) theory.\nExact analytical expressions of the electric field, the charge density and the\nnumber density are derived, which depend on the electric current density as a\nparameter. From a non-equilibrium version of the Grahame equation, which\nrelates the total space charge per cross-sectional area and the corresponding\ncontribution of the electric potential drop, the current-dependent differential\ncapacitance of the diffuse layer is derived. In the limit of vanishing electric\ncurrent these results reduce to those within Gouy-Chapman theory. It is shown\nthat improperly chosen boundary conditions lead to non-equilibrium steady state\nsolutions of the PNP equations with negative ion number densities. A necessary\nand sufficient criterion on surface conductivity constitutive relations is\nformulated which allows one to detect such unphysical solutions.",
        "positive": "S-Shaped Flow Curves of Shear Thickening Suspensions: Direct Observation\n  of Frictional Rheology: We study the rheological behavior of concentrated granular suspensions of\nsimple spherical particles. Under controlled stress, the system exhibits an\nS-shaped flow curve (stress vs. shear rate) with a negative slope in between\nthe low-viscosity Newtonian regime and the shear thickened regime. Under\ncontrolled shear rate, a discontinuous transition between the two states is\nobserved. Stress visualization experiments with a novel fluorescent probe\nsuggest that friction is at the origin of shear thickening. Stress\nvisualization shows that the stress in the system remains homogeneous (no shear\nbanding) if a stress is imposed that is intermediate between the high and\nlow-stress branches. The S-shaped shear thickening is then due to the\ndiscontinuous formation of a frictional force network between particles upon\nincreasing the stress."
    },
    {
        "anchor": "Hard sphere packings within cylinders: The packing of hard spheres (HS) of diameter $\\sigma$ in a cylinder has been\nused to model experimental systems, such as fullerenes in nanotubes and\ncolloidal wire assembly. Finding the densest packings of HS under this type of\nconfinement, however, grows increasingly complex with the cylinder diameter,\n$D$. Little is thus known about the densest achievable packings for\n$D>2.873\\sigma$. In this work, we extend the identification of the packings up\nto $D=4.00\\sigma$ by adapting Torquato-Jiao's adaptive-shrinking-cell\nformulation and sequential-linear-programming (SLP) technique. We identify 17\nnew structures, almost all of them chiral. Beyond $D\\approx2.85\\sigma$, most of\nthe structures consist of an outer shell and an inner core that compete for\nbeing close packed. In some cases, the shell adopts its own maximum density\nconfiguration, and the stacking of core spheres within it is quasiperiodic. In\nother cases, an interplay between the two components is observed, which may\nresult in simple periodic structures. In yet other cases, the very distinction\nbetween core and shell vanishes, resulting in more exotic packing geometries,\nincluding some that are three-dimensional extensions of structures obtained\nfrom packing hard disks in a circle.",
        "positive": "Shear thickening and jamming of dense suspensions: the \"roll\" of\n  friction: Particle-based simulations of discontinuous shear thickening (DST) and shear\njamming (SJ) suspensions are used to study the role of stress-activated\nconstraints, with an emphasis on resistance to gear-like rolling. Rolling\nfriction decreases the volume fraction required for DST and SJ, in quantitative\nagreement with real-life suspensions with adhesive surface chemistries and\n\"rough\" particle shapes. It sets a distinct structure of the frictional force\nnetwork compared to only sliding friction, and from a dynamical perspective\nleads to an increase in the velocity correlation length, in part responsible\nfor the increased viscosity. The physics of rolling friction is thus a key\nelement in achieving a comprehensive understanding of strongly shear-thickening\nmaterials."
    },
    {
        "anchor": "Glassy correlations and microstructures in randomly crosslinked\n  homopolymer blends: We consider a microscopic model of a polymer blend that is prone to phase\nseparation. Permanent crosslinks are introduced between randomly chosen pairs\nof monomers, drawn from the Deam-Edwards distribution. Thereby, not only\ndensity but also concentration fluctuations of the melt are quenched-in in the\ngel state, which emerges upon sufficient crosslinking. We derive a Landau\nexpansion in terms of the order parameters for gelation and phase separation,\nand analyze it on the mean-field level, including Gaussian fluctuations. The\nmixed gel is characterized by thermal as well as time-persistent (glassy)\nconcentration fluctuations. Whereas the former are independent of the\npreparation state, the latter reflect the concentration fluctuations at the\ninstant of crosslinking, provided the mesh size is smaller than the correlation\nlength of phase separation. The mixed gel becomes unstable to microphase\nseparation upon lowering the temperature in the gel phase. Whereas the length\nscale of microphase separation is given by the mesh size, at least close to the\ntransition, the emergent microstructure depends on the composition and\ncompressibility of the melt. Hexagonal structures, as well as lamellae or\nrandom structures with a unique wavelength, can be energetically favorable.",
        "positive": "A numerical study of stretched smectic-A elastomer sheets: We present a numerical study of stretching monodomain smectic-A elastomer\nsheets, computed using the finite element method. When stretched parallel to\nthe layer normal the microscopic layers in smectic elastomers are unstable to a\ntransition to a buckled state. We account for the layer buckling by replacing\nthe microscopic energy with a coarse grained effective free energy that\naccounts for the fine scale deformation of the layers. We augment this model\nwith a term to describe the energy of deforming buckled layers, which is\nnecessary to reproduce the experimentally observed Poisson's ratios\npost-buckling. We examine the spatial distribution of the microstructure phases\nfor various stretching angles relative to the layer normal, and for different\nlength-to-width aspect ratios. When stretching parallel to the layer normal the\nmajority of the sample forms a bi-directionally buckled microstructure, except\nat the clamps where uni-directional microstructure is predicted. When\nstretching at small inclinations to the layer normal the phase of the sample is\nsensitive to the aspect ratio of the sample, with the bi-directionally buckled\nphase persistent to large angles only for small aspect ratios. We relate these\ntheoretical results to experiments on smectic-A elastomers."
    },
    {
        "anchor": "MFU-type metal-organic frameworks as host materials of confined\n  supercooled liquids: In this work we examine the use of metal-organic framework (MOF) systems as\nhost materials for the investigation of glassy dynamics in confined geometry.\nWe investigate the confinement of the molecular glass former glycerol in three\nMFU-type MOFs with different pore sizes and study the dynamics of the confined\nliquid via dielectric spectroscopy. In accord with previous reports on confined\nglass formers, we find different degrees of deviations from bulk behavior\ndepending on pore size, demonstrating that MOFs are well-suited host systems\nfor confinement investigations.",
        "positive": "Avalanche statistics during coarsening dynamics: We study the coarsening dynamics of a two dimensional system via lattice\nBoltzmann numerical simulations. The system under consideration is a biphasic\nsystem consisting of domains of a dispersed phase closely packed together in a\ncontinuous phase and separated by thin interfaces. Such system is elastic and\ntypically out of equilibrium. The equilibrium state is attained via the\ncoarsening dynamics, wherein the dispersed phase slowly diffuses through the\ninterfaces, causing domains to change in size and eventually rearrange\nabruptly. The effect of rearrangements is propagated throughout the system via\nthe intrinsic elastic interactions and may cause rearrangements elsewhere,\nresulting in intermittent bursts of activity and avalanche behaviour. Here we\naim at quantitatively characterizing the corresponding avalanche statistics\n(i.e. size, duration, inter-avalanche time). Despite the coarsening dynamics is\ntriggered by an internal driving mechanism, we find quantitative indications\nthat such avalanche statistics displays scaling-laws very similar to those\nobserved in the response of disordered materials to external loads."
    },
    {
        "anchor": "Conservation of the Stokes-Einstein Relation in Supercooled Water: The Stokes-Einstein (SE) relation is commonly regarded as being breakdown in\nsupercooled water. However, this conclusion is drawn upon testing the\nvalidities of some variants of the SE relation rather than its original form,\nand it appears conflicting with the fact that supercooled water is in its local\nequilibrium. In this work, we show by molecular dynamics simulation that both\nthe Einstein and Stokes relations are indeed conserved in supercooled water.\nThe inconsistency between the original SE relation and its variants comes from\ntwo facts: (1) the substitutes of the shear viscosity in the SE variants are\nwavevector-dependent, so it is only a cursory approximation; (2) the effective\nhydrodynamic radius actually decreases with decreasing temperature, instead of\nbeing a constant as assumed in the SE variants. Besides supercooled water, this\ninconsistency may also exist in other supercooled liquids.",
        "positive": "Revealing the three-component structure of water with principal\n  component analysis (PCA) on X-ray spectrum: Combining the principal component analysis (PCA) of X-ray spectrum with MD\nsimulations, we experimentally reveal the existence of three basic components\nin water. These components exhibit distinct structures, densities, and\ntemperature dependencies. Among the three, two major components correspond to\nthe low-density liquid (LDL) and the high-density liquid (HDL) predicted by the\ntwo-component model, and the third component exhibits a unique 5-hydrogen-bond\nconfiguration with an ultra-high local density. As the temperature increases,\nthe LDL component decreases and the HDL component increases, while the third\ncomponent varies non-monotonically with a peak around 20 $^{\\circ}$C to 30\n$^{\\circ}$C. The 3D structure of the third component is further illustrated as\nthe uniform distribution of five hydrogen-bonded neighbors on a spherical\nsurface. Our study reveals experimental evidence for water's unique\nthree-component structure, which provides a fundamental basis for understanding\nwater's special properties and anomalies."
    },
    {
        "anchor": "Thawed Matrix method for computing Local Mechanical Properties of\n  Amorphous Solids: We present a method for computing locally varying nonlinear mechanical\nproperties in particle simulations of amorphous solids. Plastic rearrangements\noutside a probed region are suppressed by introducing an external field that\ndirectly penalizes large nonaffine displacements. With increasing strength of\nthe field, plastic deformation can be localized. We characterize the\ndistribution of local plastic yield stresses (residual local stresses to\ninstability) with our approach, and assess the correlation of their spatial\nmaps with plastic activity in a model two-dimensional amorphous solid. Our\napproach reduces artefacts inherent in a previous method known as the \"frozen\nmatrix\" approach that enforces fully affine deformation, and improves the\nprediction of plastic rearrangements from structural information.",
        "positive": "Near-zero surface pressure assembly of rectangular lattices of microgels\n  at fluid interfaces for colloidal lithography: Understanding and engineering the self-assembly of soft colloidal particles\n(microgels) at liquid-liquid interfaces is broadening their use in colloidal\nlithography. Here, we present a new route to assemble rectangular lattices of\nmicrogels at near zero surface pressure relying on the balance between\nattractive quadrupolar capillary interactions and steric repulsion among the\nparticles at water/oil interfaces. These self-assembled rectangular lattices\nare obtained for a broad range of particles and, after deposition, can be used\nas lithography masks to obtain regular arrays of vertically aligned nanowires\nvia wet and dry etching processes."
    },
    {
        "anchor": "Onsager's missing steps retraced: Onsager's paper on phase transition and phase coexistence in anisotropic\ncolloidal systems is a landmark in the theory of lyotropic liquid crystals.\nHowever, an uncompromising scrutiny of Onsager's original derivation reveals\nthat it would be rigorously valid only for ludicrous values of the system's\nnumber density (of the order of the reciprocal of the number of particles)\nBased on Penrose's tree identity and an appropriate variant of the mean-field\napproach for purely repulsive, hard-core interactions, our theory shows that\nOnsager's theory is indeed valid for a reasonable range of densities.",
        "positive": "Ion-induced transient potential fluctuations facilitate pore formation\n  and cation transport through lipid membranes: Unassisted ion transport through lipid membranes plays a crucial role in many\ncell functions without which life would not be possible, yet the precise\nmechanism behind the process remains unknown due to its molecular complexity.\nHere, we demonstrate a direct link between membrane potential fluctuations and\ndivalent ion transport. High-throughput wide-field second harmonic (SH)\nmicroscopy shows that membrane potential fluctuations are universally found in\nlipid bilayer systems. Molecular dynamics simulations reveal that such\nvariations in membrane potential reduce the free energy cost of transient pore\nformation and increase the ion flux across an open pore. These transient pores\ncan act as conduits for ion transport, which we SH image for a series of\ndivalent cations (Cu$^{2+}$, Ca$^{2+}$, Ba$^{2+}$, Mg$^{2+}$) passing through\nGUV membranes. Combining the experimental and computational results, we show\nthat permeation through pores formed via an ion-induced electrostatic field is\na viable mechanism for unassisted ion transport."
    },
    {
        "anchor": "Unusual liquid phases for indented colloids with depletion interactions: We study indented spherical colloids, interacting via depletion forces. These\nsystems exhibit liquid-vapor phase transitions whose properties are determined\nby a combination of strong \"lock-and-key\" bonds and weaker non-specific\ninteractions. As the propensity for lock-and-key binding increases, the\ncritical point moves to significantly lower density, and the coexisting phases\nchange their structure. In particular, the liquid phase is \"porous\", exhibiting\nlarge percolating voids. The properties of this system depend strongly on the\ntopological structure of an underlying bond network: we comment on the\nimplications of this fact for the assembly of equilibrium states with\ncontrolled porous structures.",
        "positive": "Predicting phase equilibria in polydisperse systems: Many materials containing colloids or polymers are polydisperse: They\ncomprise particles with properties (such as particle diameter, charge, or\npolymer chain length) that depend continuously on one or several parameters.\nThis review focusses on the theoretical prediction of phase equilibria in\npolydisperse systems; the presence of an effectively infinite number of\ndistinguishable particle species makes this a highly nontrivial task. I first\ndescribe qualitatively some of the novel features of polydisperse phase\nbehaviour, and outline a theoretical framework within which they can be\nexplored. Current techniques for predicting polydisperse phase equilibria are\nthen reviewed. I also discuss applications to some simple model systems\nincluding homopolymers and random copolymers, spherical colloids and\ncolloid-polymer mixtures, and liquid crystals formed from rod- and plate-like\ncolloidal particles; the results surveyed give an idea of the rich\nphenomenology of polydisperse phase behaviour. Extensions to the study of\npolydispersity effects on interfacial behaviour and phase separation kinetics\nare outlined briefly."
    },
    {
        "anchor": "Effects of surface charge and environmental factors on the electrostatic\n  interaction of fiber with virus-like particle: A case of coronavirus: We propose a theoretical model to elucidate intermolecular electrostatic\ninteractions between a virus and a substrate. Our model treats the virus as a\nhomogeneous particle having surface charge and the polymer fiber of the\nrespirator as a charged plane. Electric potentials surrounding the virus and\nfiber are influenced by the surface charge distribution of the virus. We use\nPoisson-Boltzmann equations to calculate electric potentials. Then, Derjaguin's\napproximation and a linear superposition of the potential function are extended\nto determine the electrostatic force. In this work, we apply this model for\ncoronavirus or SARS-CoV-2 case and numerical results quantitatively agree with\nprior simulation. We find that the influence of fiber's potential on the\nsurface charge of the virus is important and is considered in interaction\ncalculations to obtain better accuracy. The electrostatic interaction\nsignificantly decays with increasing separation distance, and this curve\nbecomes steeper when adding more salt. Although the interaction force increases\nwith heating, one can observe the repulsive-attractive transition when the\nenvironment is acidic.",
        "positive": "Hydrodynamic fluctuation forces: Two interaction mechanisms of particles in a fluid are proposed on base of\nforces, mediated by hydrodynamic thermal fluctuations. The first one is similar\nto the conventional van der Waals interaction, but instead of been mediated by\nelectromagnetic fluctuations, it is mediated by fluctuations of hydrodynamic\nsound waves. The second one is due to a thermal drift of particles to the\nregion with a bigger effective mass, which is formed by the involved\nsurrounding fluid and depends on an inter-particle distance. The both\nmechanisms likely can be relevant in interpretation of the observed long-range\nattraction of colloidal particles, since a set different experiments shows the\nattraction energy of the order of kT and, perhaps, only a fluctuation mechanism\nof attarction provides this universality."
    },
    {
        "anchor": "A minimal model for liquid-liquid phase separation and aging of\n  chemically reactive macromolecular mixtures: Mixtures of several macromolecular species can lead to the formation of\nhigher-order structures that often display non-ideal mixing behavior. In this\nwork, we propose a minimal model of a quaternary system which considers the\nformation of a complex via a chemical reaction involving two macromolecular\nspecies; the complex may then phase separate from the buffer and undergo a\nfurther transition into a gel-like state over time. First, a ternary phase\ndiagram that captures the volume fraction of each species and phases at\nequilibrium is constructed. Specifically, we investigate how physical\nparameters such as stoichiometric coefficients, molecular sizes and interaction\nparameters affect LLPS and aging. Finally, we analyze the thermodynamic\nstability of the two-phase system and identify the spinodal regions, and\noutline the generalization of our approach to reactive biomolecular systems\nwith an arbitrary number of components.",
        "positive": "Single Active Ring Model: Cellular tissue behavior is a multiscale problem. At the cell level, out of\nequilibrium, biochemical reactions drive physical cell-cell interactions in a\ntypical active matter process. Cell modeling computer simulations are a robust\ntool to explore the countless possibilities and test hypotheses. Here, we\nintroduce a two dimensional, extended active matter model for biological cells.\nA ring of interconnected self-propelled particles represents the cell.\nTranslational modes, rotational modes, and mixtures of these appear as\ncollective states. Using analytic results derived from active Brownian\nparticles, we identify effective characteristic time scales for ballistic and\ndiffusive movements. Finite-size scale investigation shows that the ring\ndiffusion increases linearly with its size when in collective movement. A study\non the ring shape reveals that all collective states are present even when\nbending forces are weak. In that case, when in translational mode, the\ncollective velocity aligns with the largest ring's direction in a spontaneous\npolarization emergence."
    },
    {
        "anchor": "The Electric Double Layer Structure Around Charged Spherical Interfaces: We derive a formally simple approximate analytical solution to the\nPoisson-Boltzmann equation for the spherical system via a geometric mapping.\nIts regime of applicability in the parameter space of the spherical radius and\nthe surface potential is determined, and its superiority over the linearized\nsolution is demonstrated.",
        "positive": "Transient coarsening and the motility of optically heated Janus colloids\n  in a binary liquid mixture: A gold-capped Janus particle suspended in a near-critical binary liquid\nmixture can self-propel under illumination. We have immobilized such a particle\nin a narrow channel and studied the nonequilibrium dynamics of a binary solvent\naround it, using experiment and numerical simulations. For the latter we\nconsider both a purely diffusive and a hydrodynamic model. All approaches\nindicate that the early time dynamics is purely diffusive and characterized by\ncomposition layers traveling with a constant speed from the surface of the\ncolloid into the bulk. Subsequently, hydrodynamic effects set in and the\ntransient state is destroyed by strong nonequilibrium concentration\nfluctuations, which arise as a result of the temperature gradient and the\nvicinity of the critical point of the binary liquid mixture. They give rise to\na complex, permanently changing coarsening patterns. For a mobile particle, the\ntransient dynamics results in propulsion in the direction opposite to that\nobserved after the steady state is attained."
    },
    {
        "anchor": "Motion of active tracer in a lattice gas with cross-shaped particles: We analyze the dynamics of an active tracer particle embedded in a thermal\nlattice gas. All particles are subject to exclusion up to third nearest\nneighbors on the square lattice, which leads to slow dynamics at high\ndensities. For the case with no rotational diffusion of the tracer, we derive\nan analytical expression for the resulting drift velocity v of the tracer in\nterms of non-equilibrium density correlations involving the tracer particle and\nits neighbors, which we verify using numerical simulations. We show that the\nproperties of the passive system alone do not adequately describe even this\nsimple system of a single non-rotating active tracer. For large activity and\nlow density, we develop an approximation for v. For the case where the tracer\nundergoes rotational diffusion independent of its neighbors, we relate its\ndiffusion coefficient to the thermal diffusion coefficient and v. Finally we\nstudy dynamics where the rotation of the tracer is limited by the presence of\nneighboring particles. We find that the effect of this rotational locking may\nbe quantitatively described in terms of a reduction of the rotation rate.",
        "positive": "Intrusion into granular media beyond the quasi-static regime: The drag force exerted on an object intruding into granular media can depend\non the object's velocity as well as the depth penetrated. We report on\nintrusion experiments at constant speed over four orders in magnitude together\nwith systematic molecular dynamics simulations well beyond the quasi-static\nregime. We find that velocity dependence crosses over to depth dependence at a\ncharacteristic time after initial impact. This crossover time scale, which\ndepends on penetration speed, depth, gravity and intruder geometry, challenges\ncurrent models that assume additive contributions to the drag."
    },
    {
        "anchor": "A combined experimental and numerical study of stab-penetration forces: The magnitude of force used in a stabbing incident can be difficult to\nquantify, although the estimate given by forensic pathologists is often seen as\n`critical' evidence in medico-legal situations. The main objective of this\nstudy is to develop a quantitative measure of the force associated with a knife\nstabbing biological tissue, using a combined experimental and numerical\ntechnique. A series of stab-penetration tests were performed to quantify the\nforce required for a blade to penetrate skin at various speeds and using\ndifferent `sharp' instruments. A computational model of blade penetration was\ndeveloped using ABAQUS/EXPLICIT, a non-linear finite element analysis (FEA)\ncommercial package. This model, which incorporated element deletion along with\na suitable failure criterion, is capable of systematically quantifying the\neffect of the many variables affecting a stab event. This quantitative data\ncould, in time, lead to the development of a predictive model that could help\nindicate the level of force used in a particular stabbing incident.",
        "positive": "A slime mold inspired local adaptive mechanism for flow networks: In the realm of biological flow networks, the ability to dynamically adjust\nto varying demands is paramount. Drawing inspiration from the remarkable\nadaptability of Physarum polycephalum, we present a novel physical mechanism\ntailored to optimize flow networks. Central to our approach is the principle\nthat each network component -- specifically, the tubes -- harnesses locally\navailable information to collectively minimize a global cost function. Our\nfindings underscore the scalability of this mechanism, making it feasible for\nlarger, more complex networks. We construct a comprehensive phase diagram,\npinpointing the specific network parameters under which successful adaptation,\nor tuning, is realized. There exists a phase boundary in the phase diagram,\nrevealing a distinct satisfiability-unsatisfiability (SAT-UNSAT) phase\ntransition delineating successful and unsuccessful adaptation."
    },
    {
        "anchor": "Accretion-Ablation Mechanics: In this paper we formulate a geometric nonlinear theory of the mechanics of\naccreting-ablating bodies. This is a generalization of the theory of accretion\nmechanics of Sozio and Yavari (2019). More specifically, we are interested in\nlarge deformation analysis of bodies that undergo a continuous and simultaneous\naccretion and ablation on their boundaries while under external loads. In this\nformulation the natural configuration of an accreting-ablating body is a\ntime-dependent Riemannian 3-manifold with a metric that is an unknown a priori\nand is determined after solving the accretion-ablation initial-boundary-value\nproblem. In addition to the time of attachment map, we introduce a time of\ndetachment map that along with the time of attachment map, and the accretion\nand ablation velocities describes the time-dependent reference configuration of\nthe body. The kinematics, material manifold, material metric, constitutive\nequations, and the balance laws are discussed in detail. As a concrete example\nand application of the geometric theory, we analyze a thick hollow circular\ncylinder made of an arbitrary incompressible isotropic material that is under a\nfinite time-dependent extension while undergoing continuous ablation on its\ninner cylinder boundary and accretion on its outer cylinder boundary. The state\nof deformation and stress during the accretion-ablation process, and the\nresidual stretch and stress after the completion of the accretion-ablation\nprocess are computed.",
        "positive": "An analytical coarse-graining method which preserves the free energy,\n  structural correlations, and thermodynamic state of polymer melts from the\n  atomistic to the mesoscale: Structural and thermodynamic consistency of coarse-graining models across\nmultiple length scales is essential for the predictive role of multi-scale\nmodeling and molecular dynamic simulations that use mesoscale descriptions. Our\napproach is a coarse-grained model based on integral equation theory, which can\nrepresent polymer chains at variable levels of chemical details. The model is\nanalytical and depends on molecular and thermodynamic parameters of the system\nunder study, as well as on the direct correlation function in the k --> 0\nlimit, c0. A numerical solution to the PRISM integral equations is used to\ndetermine c0, by adjusting the value of the effective hard sphere diameter, d,\nto agree with the predicted equation of state. This single quantity\nparameterizes the coarse-grained potential, which is used to perform mesoscale\nsimulations that are directly compared with atomistic-level simulations of the\nsame system. We test our coarse-graining formalism by comparing structural\ncorrelations, isothermal compressibility, equation of state, Helmholtz and\nGibbs free energies, and potential energy and entropy using both united atom\nand coarse-grained descriptions. We find quantitative agreement between the\nanalytical formalism for the thermodynamic properties, and the results of\nMolecular Dynamics simulations, independent of the chosen level of\nrepresentation. In the mesoscale description, the potential energy of the\nsoft-particle interaction becomes a free energy in the coarse-grained\ncoordinates which preserves the excess free energy from an ideal gas across all\nlevels of description. The structural consistency between the united-atom and\nmesoscale descriptions means the relative entropy between descriptions has been\nminimized without any variational optimization parameters. The approach is\ngeneral and applicable to any polymeric system in different thermodynamic\nconditions."
    },
    {
        "anchor": "Molecular-Dynamics Simulation of a Glassy Polymer Melt: Rouse Model and\n  Cage Effect: We report results of molecular-dynamics simulations for a glassy polymer melt\nconsisting of short, linear bead-spring chains. It was shown in previous work\nthat this onset of the glassy slowing down is compatible with the predictions\nof the mode coupling theory. The physical process of `caging' of a monomer by\nits spatial neighbors leads to a distinct two step behavior in the particle\nmean square displacements. In this work we analyze the effects of this caging\nprocess on the Rouse description of the melt's dynamics. We show that the Rouse\ntheory is applicable for length and time scales above the typical scales for\nthe caging process. Futhermore, the monomer displacement is compared with\nsimulation results for a binary Lennard-Jones mixture to point out the\ndifferences which are introduced by the connectivity of the particles.",
        "positive": "Shear-induced memory effects in boehmite gels: Colloidal gels are formed by the aggregation of Brownian particles into\nclusters that are, in turn, part of a space-spanning percolated network. In\npractice, the microstructure of colloidal gels, which dictates their mechanical\nproperties, strongly depends on the particle concentration and on the nature of\ntheir interactions. Yet another critical control parameter is the shear history\nexperienced by the sample, which controls the size and density of the cluster\npopulation, via particle aggregation, cluster breakup, and restructuring. Here\nwe investigate the impact of shear history on acid-induced gels of boehmite, an\naluminum oxide. We show that following a primary gelation, these gels display a\ndual response depending on the shear rate $\\dot\\gamma_{\\rm p}$ used to\nrejuvenate their microstructure. We identify a critical shear rate\n$\\dot\\gamma_{\\rm c}$, above which boehmite gels display a gel-like viscoelastic\nspectrum upon flow cessation, similar to that obtained following the primary\ngelation. However, upon flow cessation after shear rejuvenation below\n$\\dot\\gamma_{\\rm c}$, boehmite gels display a glassy-like viscoelastic spectrum\ntogether with enhanced elastic properties. Moreover, the nonlinear rheological\nproperties of boehmite gels also differ on both sides of $\\dot\\gamma_{\\rm c}$:\nweak gels obtained after rejuvenation at $\\dot\\gamma_{\\rm p}>\\dot\\gamma_{\\rm\nc}$ show a yield strain that is constant, independent of $\\dot\\gamma_{\\rm p}$,\nwhereas strong gels obtained with $\\dot\\gamma_{\\rm p}<\\dot\\gamma_{\\rm c}$\ndisplay a yield strain that significantly increases with $\\dot\\gamma_{\\rm p}$.\nOur results can be interpreted in light of previous literature on shear-induced\nanisotropy, while we rationalize the critical shear rate in terms of a\ndimensionless quantity, the Mason number, comparing the strength of the shear\nflow to the interparticle bond force."
    },
    {
        "anchor": "A Facile Approach to Prepare Self-Assembled, Nacre-Inspired Clay/Polymer\n  Nano-Composites: Nature provides many paradigms for the design and fabrication of artificial\ncomposite materials. Inspired by the relationship between the well-ordered\narchitecture and biopolymers found in natural nacre, we present a facile\nstrategy to construct large-scale organic/inorganic nacre-mimetics with\nhierarchical structure via a water-evaporation self-assembly process. Through\nhydrogen bonding, we connect Laponite-nanoclay platelets with each other using\nnaturally abundant cellulose creating thin, flexible films with a local\nbrick-and-mortar architecture. While the aqueous solution displays liquid\ncrystalline textures, the dried films show a pronounced Young's modulus (9.09\nGPa) with a maximum strength of 298.02 MPa and toughness of 16.63 MJm-3. In\nterms of functionalities, we report excellent glass-like transparency along\nwith exceptional shape-persistent flame shielding. We also demonstrate that\nthrough metal ion-coordination we can further strengthen the interactions\nbetween the polymers and the nanoclays. These ion-treated hybrid films exhibit\nfurther enhanced mechanical, and thermal properties as well as resistance\nagainst swelling and dissolution in aqueous environments. We believe that our\nsimple pathway to fabricate such versatile polymer/clay nanocomposites can open\navenues for inexpensive production of environmentally friendly, biomimetic\nmaterials in aerospace, wearable electrical devices, artificial muscle, and\nfood packaging industry.",
        "positive": "Ewald summation for ion-dipole mixture under dielectric confinement: A modified 3D-Ewald summation is presented for accurately simulating the\nion-dipole mixture under dielectric confinement. The method is based on the\ncombination of image charges and image dipoles with the conventional Ewald\nsummation and has a scaling O(^3/2). The accuracy and efficiency of our\nalgorithm are examined through numerical examples."
    },
    {
        "anchor": "Impact of Interaction Range and Curvature on Crystal Growth of Particles\n  Confined to Spherical Surfaces: When colloidal particles form a crystal phase on a spherical template, their\npacking is governed by the effective interaction between them and the elastic\nstrain of bending the growing crystal. For example, if growth commences under\nappropriate conditions, and the circular crystal that forms reaches a critical\nsize, growth continues by incorporation of defects to alleviate elastic strain.\nRecently it was found experimentally that, if defect formation is somehow not\npossible, the crystal instead continues growing in ribbons that protrude from\nthe original crystal. Here we report on computer simulations in which we\nobserve both the formation of ribbons at short interaction ranges and packings\nthat incorporate defects if the interaction is longer-ranged. The ribbons only\nform above some critical crystal size, below which the nucleus is roughly\nspherically shaped. We find that the scaling of the critical crystal size\ndiffers slightly from the one proposed by the Manoharan group, and reason this\nis because the actual process is a two-step heterogeneous nucleation of ribbons\non top of roughly circular crystals.",
        "positive": "Thin-thick coexistence behavior of 8CB liquid crystalline films on\n  silicon: The wetting behavior of thin films of 4'-n-octyl-4-cyanobiphenyl (8CB) on Si\nis investigated via optical and x-ray reflectivity measurement. An experimental\nphase diagram is obtained showing a broad thick-thin coexistence region\nspanning the bulk isotropic-to-nematic ($T_{IN}$) and the nematic-to-smectic-A\n($T_{NA}$) temperatures. For Si surfaces with coverages between 47 and $72\\pm3$\nnm, reentrant wetting behavior is observed twice as we increase the\ntemperature, with separate coexistence behaviors near $T_{IN}$ and $T_{NA}$.\nFor coverages less than 47 nm, however, the two coexistence behaviors merge\ninto a single coexistence region. The observed thin-thick coexistence near the\nsecond-order NA transition is not anticipated by any previous theory or\nexperiment. Nevertheless, the behavior of the thin and thick phases within the\ncoexistence regions is consistent with this being an equilibrium phenomenon."
    },
    {
        "anchor": "Semi-classical buckling of stiff polymers: A quantitative theory of the buckling of a worm like chain based on a\nsemi-classical approximation of the partition function is presented. The\ncontribution of thermal fluctuations to the force-extension relation that\nallows to go beyond the classical Euler buckling is derived in the linear and\nnon-linear regime as well. It is shown that the thermal fluctuations in the\nnonlinear buckling regime increase the end-to-end distance of the semiflexible\nrod if it is confined to 2 dimensions as opposed to the 3 dimensional case. Our\napproach allows a complete physical understanding of buckling in D=2 and in D=3\nbelow and above the Euler transition.",
        "positive": "New approach to Monte Carlo calculation of buckling of supercoiled DNA\n  loops: The short supercoiled circular DNA molecules are shown to be glassy systems\nand canonical Metropolis Monte Carlo simulations of the systems tend to get\nstuck in local metastable energy basins. A novel Monte Carlo algorithm is\ndeveloped to alleviate the problem of ``ergodicity breaking'' of the glassy\nsystems, in which the Markov process is driven by an explicitly analytic weight\nfactor with enhanced probability in both low- and high-energy regions. To\ncharacterize the degree of puckering of the supercoiled DNA loops, a new\nquantity of aplanarity is introduced as the shortest principal axis of\nconfigurational ellipsoid of DNA. With the suggested Monte Carlo method, the\nquantitative correlation between supercoiling degree and buckling of DNA is\nattained. With supercoiling stress increasing, the conformational transition\nfrom a circle to mono-, diplo- or triple interwound superhelical structure will\ntake place in a successive but decreasingly abrupt mode."
    },
    {
        "anchor": "Controlling polymer translocation with crowded medium and polymer length\n  asymmetry: Polymer translocation in crowded environments is a ubiquitous phenomenon in\nbiological systems. We studied polymer translocation through a pore in free,\none-sided (asymmetric), and two-sided (symmetric) crowded environments.\nExtensive Langevin dynamics simulation is employed to model the dynamics of the\nflexible polymer and crowding particles. We studied how crowding size and\npacking fraction play a crucial role in the translocation process. After\ndetermining the standard scaling properties of the translocation probability,\ntime, and MSD, we observed that the translocation rate and bead velocities are\nlocation-dependent as we move along the polymer backbone, even in a crowd-free\nenvironment. Counter-intuitively, translocation rate and bead velocities showed\nthe opposite behavior; for example, middle monomers near the pore exhibit\nmaximum bead velocity and minimum translocation rate. Free energy calculation\nfor asymmetrically placed polymer indicates there exists a critical number of\nsegments that make the polymer to prefer the receiver side for translocation.\nFor one-sided crowding, we have identified a critical crowding size above which\nthere exists a non-zero probability to translocate into the crowding side\ninstead of the free side. Moreover, we have observed that shifting the polymer\ntowards the crowded side compensates for one-sided crowding, yielding an equal\nprobability akin to a crowder-free system. Under two-sided crowding, the\nmechanism of how a slight variation in crowder size and packing fraction can\nforce a polymer to switch its translocation direction is proposed, which has\nnot been explored before. Using this control we achieved an equal translocation\nprobability like a crowd-free scenario. These conspicuous yet counter-intuitive\nphenomena are rationalized by simple theoretical arguments based on osmotic\npressure and radial entropic forces.",
        "positive": "Surface melting of a colloidal glass: Despite their technological relevance, a full microscopic understanding of\nglasses is still lacking. This applies even more to their surfaces whose\nproperties largely differ from that of the bulk material. Here, we\nexperimentally investigate the surface of a two-dimensional glass as a function\nof the effective temperature. To yield a free surface, we use an attractive\ncolloidal suspension of micron-sized particles interacting via tunable critical\nCasimir forces. Similar to crystals, we observe surface melting of the glass,\ni.e., the formation of a liquid film at the surface well below the glass\ntemperature. Underneath, however, we find an unexpected region with bulk\ndensity but much faster particle dynamics. It results from connected clusters\nof highly mobile particles which are formed near the surface and deeply\npercolate into the underlying material. Because its thickness can reach several\ntens of particle diameters, this layer may elucidate the poorly understood\nproperties of thin glassy films which find use in many technical applications"
    },
    {
        "anchor": "Molecular Weight Dependence of Spreading Rates of Ultrathin Polymeric\n  Films: We study experimentally the molecular weight $M$ dependence of spreading\nrates of molecularly thin precursor films, growing at the bottom of droplets of\npolymer liquids. In accord with previous observations, we find that the radial\nextension R(t) of the film grows with time as R(t) = (D_{exp} t)^{1/2}. Our\ndata substantiate the M-dependence of D_{exp}; we show that it follows D_{exp}\n\\sim M^{-\\gamma}, where the exponent \\gamma is dependent on the chemical\ncomposition of the solid surface, determining its frictional properties with\nrespect to the molecular transport. In the specific case of hydrophilic\nsubstrates, the frictional properties can be modified by the change of the\nrelative humidity (RH). We find that \\gamma \\approx 1 at low RH and tends to\nzero when RH gets progressively increased. We propose simple theoretical\narguments which explain the observed behavior in the limits of low and high RH.",
        "positive": "Electrical, elastic properties and defect structures of isotactic\n  polypropylene composites doped with nanographite and graphene nanoparticles: Conducting polymers have wide technological applications in sensors,\nactuators, electric and optical devices, solar cells etc. To improve their\noperational performance, mechanical, thermal, electrical and optical\nproperties, such polymers are doped with carbon allotrope nanofillers.\nFunctionality of the novel nanocomposite polymers may be stipulated by size\ncharacteristics of nanoparticles and the polymer, different physical effects\nlike charge transfer in such objects etc. We characterize and analyze\nstructure, elastic, electric properties and of novel polymer nanocomposites,\nisotactic polypropylene (iPP) with high crystallinity, doped with graphene\nnanoplates (GNP) and nanographite particles at different concentrations and\nsizes about 100 nm, basing on the results of dynamic mechanical analysis (DMA),\ndielectric spectroscopy, small-angle neutron scattering (SANS) and theoretical\nmodeling. Carbon NPs aggregated in fractal objects in the bulk of iPP change\nits mechanical plastic, elastic and electric properties comparing with pristine\npolymer. We study modification of nanofiller morphology with the concept of\nCosserat elasticity which involves description of the behavior of linear\ntopological defects caused aggregation of nanographite and GNPs. We supply our\nexperimental data with numerical simulations on the lattice in frames of the\nmodel of Cosserat elasticity to estimate some mechanical characteristics of the\nwhole composite iPP."
    },
    {
        "anchor": "Scaling between structural relaxation and caged dynamics in\n  Ca_{0.4}K_0.6(NO_{3})_{1.4} and glycerol: free volume, time scales and\n  implications for the pressure-energy correlations: The scaling of the slow structural relaxation with the fast caged dynamics is\nevidenced in the molten salt Ca_{0.4}K_{0.6}(NO_{3}$)_{1.4} (CKN) over about\nthirteen decades of the structural relaxation time. Glycerol caling was\nanalyzed in detail. In glycerol, the short-time mean-square displacement <u^2>,\na measure of the caged dynamics, is contributed by free-volume. It is seen\nthat, in order to evidence the scaling, the observation time of the fast\ndynamics must be shorter than the time scales of the relaxation processes.\nSystems with both negligible (like CKN, glycerol and network glassformers) and\nhigh (like van der Waals liquids and polymers) pressure-energy correlations\nexhibit the scaling between the slow relaxation and the fast caged dynamics.\nAccording to the available experiments, an isomorph-invariant expression of the\nmaster curve of the scaled data is not distinguishable from a simpler\nnot-invariant expression. Instead, the latter grees better with the simulations\non a wide class of model polymers.",
        "positive": "Effective mass analysis of Bose-Einstein condensates in optical lattices\n  -- stabilization and levitation: We investigate the time evolution of a Bose-Einstein condensate in a periodic\noptical potential. Using an effective mass formalism, we study the equation of\nmotion for the envelope function modulating the Bloch states of the lattice\npotential. In particular, we show how the negative effective mass affects the\ndynamics of the condensate."
    },
    {
        "anchor": "Polymer glass transition occurs at the marginal rigidity point with\n  connectivity z*=4: We re-examine the physical origin of the polymer glass transition from the\npoint of view of marginal rigidity, which is achieved above a certain number of\nintermolecular contacts. In the case of polymer chains in a melt / poor\nsolvent, each monomer has two neighbors bound by covalent bonds and also a\nnumber of central-force contacts modelled by the Lennard-Jones (LJ) potential.\nWe find that when the average number of contacts per monomer (covalent and\nnon-covalent) exceeds the critical value z*=4, the system becomes solid and the\ndynamics arrested - a state that we declare the glass. Coarse-grained Brownian\ndynamics simulations show that at sufficient strength of LJ attraction (which\neffectively represents the depth of quenching, or the quality of solvent) the\npolymer globule indeed crosses the threshold of z*=4, and does become a glass.\nWe verify this by showing the distinction between the `liquid' polymer droplet\nat z<z*, which changes shape and adopts the spherical conformation in\nequilibrium, and the `glassy' droplet at z>z*, which retains its shape frozen\nat the moment of z* crossover. These results provide a robust working criterion\nto tell the liquid apart from the glass for the linear polymers.",
        "positive": "Emergence of Accurate Atomic Energies from Machine Learned Noble Gas\n  Potentials: The quantum theory of atoms in molecules (QTAIM) gives access to well-defined\nlocal atomic energies. Due to their locality, these energies are potentially\ninteresting in fitting atomistic machine learning models as they inform about\nphysically relevant properties. However, computationally, quantum-mechanically\naccurate local energies are notoriously difficult to obtain for large systems.\nHere, we show that by employing semi-empirical correlations between different\ncomponents of the total energy, we can obtain well-defined local energies at a\nmoderate cost. We employ this methodology to investigate energetics in noble\nliquids or argon, krypton, and their mixture. Instead of using these local\nenergies to fit atomistic models, we show how well these local energies are\nreproduced by machine-learned models trained on the total energies. The results\nof our investigation suggest that smaller neural networks, trained only on the\ntotal energy of an atomistic system, are more likely to reproduce the\nunderlying local energy partitioning faithfully than larger networks.\nFurthermore, we demonstrate that networks more capable of this energy\ndecomposition are, in turn, capable of transferring to previously unseen\nsystems. Our results are a step towards understanding how much physics can be\nlearned by neural networks and where this can be applied, particularly how a\nbetter understanding of physics aids in the transferability of these neural\nnetworks."
    },
    {
        "anchor": "Foaming and antifoaming in non-aqueous liquids: Investigation into the physics of foaming has traditionally been focused on\naqueous systems. Non-aqueous foams, by contrast, are not well understood, but\nhave been the subject of a recent surge in interest motivated by the need to\nmanage foaming across industrial applications. In this review, we provide a\ncomprehensive discussion of the current state-of-the-art methods for\ncharacterizing non-aqueous foams, with a critical evaluation of the advantages\nand limitations of each. Subsequently we present a concise overview of the\ncurrent understanding of the mechanisms and methods used for stabilizing and\ndestabilizing non-aqueous foams. We conclude the review by discussing open\nquestions to guide future investigations.",
        "positive": "Double Asymptotic Structures of Topologically Interlocked Molecules: The mean square size of topologically interlocked molecules (TIMs) is\npresented as a linear combination of contributions from the backbone and\nsubcomponents. Using scaling analyses and extensive molecular dynamics\nsimulations of polycatenanes, as a typical example of TIMs, we show that the\neffective exponent $\\nu(m)$ for the size dependence of the backbone on the\nmonomer number of subcomponent $m$ is asymptotic to a value $\\nu$\n(approximately 0.588 in good solvents) with a correction of $m^{-0.47}$, which\nis the same as for the covalently linked polymer. However, the effective\nexponent for the size dependence of subcomponents on $m$ is asymptotic to the\nsame value $\\nu$ but with a new correction of $m^{-1.0}$. The different\ncorrections to the scaling on the backbone and subcomponent structure induce a\nsurprising double asymptotic behavior for the architecture of the TIMs. The\nscaling model that takes into account the double asymptotic behavior is in good\nquantitative agreement with the simulation result that the effective exponent\nfor the size dependence of TIMs on $m$ increases with the subcomponent number\n$n$. The full scaling functional form of the size dependence on $m$ and $n$ for\npolycatenanes in a good solvent is well described by a simple sum of two\nlimiting behaviors with different corrections."
    },
    {
        "anchor": "Surfactant concentration modulates the motion and placement of\n  microparticles in an inhomogeneous electric field: This study examined the effects of surfactants on the motion and positioning\nof microparticles in an inhomogeneous electric field. The microparticles were\nsuspended in oil with a surfactant and the electric field was generated using\nsawtooth-patterned electrodes. The microparticles were trapped, oscillated, or\nattached to the electrodes. The proportion of microparticles in each state was\ndefined by the concentration of surfactant and the voltage applied to the\nelectrodes. Based on the trajectory of the microparticles in the electric\nfield, a newly developed physical model in which the surfactant was adsorbed on\nthe microparticles allowed the microparticles to be charged by contact with the\nelectrodes, with either positive or negative charges, while the non-adsorbed\nsurfactant micellizing in the oil contributed to charge relaxation. A\nsimulation based on this model showed that the charging and charge relaxation,\nas modulated by the surfactant concentration, can explain the trajectories and\nproportion of the trapped, oscillating, and attached microparticles. These\nresults will be useful for the development of novel self-assembly and transport\ntechnologies and colloids sensitive to electricity.",
        "positive": "Ground-state properties of tubelike flexible polymers: In this work we investigate structural properties of native states of a\nsimple model for short flexible homopolymers, where the steric influence of\nmonomeric side chains is effectively introduced by a thickness constraint. This\ngeometric constraint is implemented through the concept of the global radius of\ncurvature and affects the conformational topology of ground-state structures. A\nsystematic analysis allows for a thickness-dependent classification of the\ndominant ground-state topologies. It turns out that helical structures,\nstrands, rings, and coils are natural, intrinsic geometries of such tubelike\nobjects."
    },
    {
        "anchor": "Effect of surface-active contaminants on radial thermocapillary flows: We study the thermocapillary creeping flow induced by a thermal gradient at\nthe liquid-air interface in the presence of insoluble surfactants (impurities).\nConvective sweeping of the surfactants causes density inhomogeneities that\nconfers in-plane elastic features to the interface. This mechanism is discussed\nfor radially symmetric temperature fields, in both the deep and shallow water\nregimes. When mass transport is controlled by convection, it is found that\nsurfactants are depleted from a region whose size is inversely proportional to\nthe interfacial elasticity. Both the concentration and the velocity fields\nfollow power laws at the border of the depleted region. Finally, it is shown\nthat this singular behavior is smeared out when molecular diffusion is\naccounted for.",
        "positive": "Liquid droplets act as \"compass needles\" for the stresses in a\n  deformable membrane: We examine the shape of droplets atop deformable thin elastomeric films\nprepared with an anisotropic tension. As the droplets generate a deformation in\nthe taut film through capillary forces, they assume a shape that is elongated\nalong the high tension direction. By measuring the contact line profile, the\ntension in the membrane can be completely determined. Minimal theoretical\narguments lead to predictions for the droplet shape and membrane deformation\nthat are in excellent agreement with the data. On the whole, the results\ndemonstrate that droplets can be used as probes to map out the stress field in\na membrane."
    },
    {
        "anchor": "Free energy of sheared colloidal glasses: We develop a free energy framework to describe the response of glasses to\napplied stress. Unlike crystals, for which the free energy increases\nquadratically with strain due to affine displacements, for glasses, the\nnonequilibrium free energy decreases due to complex interplay of non-affine\ndisplacements and dissipation. We measure this free energy directly in strained\ncolloidal glasses, and use mean-field theory to relate it to affine and\nnonaffine displacements. Nonaffine displacements grow with applied shear due to\nshear-induced loss of structural connectivity. Our mean-field model allows for\nthe first time to disentangle the complex contributions of affine and nonaffine\ndisplacements and dissipation in the transient deformation of glasses.",
        "positive": "Rheology of hydrating cement paste: crossover between two aging\n  processes: The roles of applied strain and temperature on the hydration dynamics of\ncement paste are uncovered in the present study. We find that the system\nhardens over time through two different aging processes. The first process\ndominates the initial period of hydration and is characterized by the shear\nstress $\\sigma$ varying sub-linearly with the strain-rate $\\dot{\\gamma}$;\nduring this process the system is in a relatively low-density state and the\ninter-particle interactions are dominated by hydrodynamic lubrication. At a\nlater stage of hydration the system evolves to a high-density state where the\ninteractions become frictional, and $\\sigma$ varies super-linearly with\n$\\dot{\\gamma}$; this is identified as the second process. An instability,\nindicated by a drop in $\\sigma$, that is non-monotonic with $\\dot{\\gamma}$ and\ncan be tuned by temperature, separates the two processes. Both from rheology\nand microscopy studies we establish that the observed instability is related to\nfracture mechanics of space-filling structure."
    },
    {
        "anchor": "Structure and thermodynamics of two dimensional Yukawa liquids: The thermodynamic and structural properties of two dimensional dense Yukawa\nliquids are studied with molecular dynamics simulations. The \"exact\"\nthermodynamic properties are simultaneously employed in an advanced scheme for\nthe determination of an equation of state that shows an unprecedented level of\naccuracy for the internal energy, pressure and isothermal compressibility. The\n\"exact\" structural properties are utilized to formulate a novel empirical\ncorrection to the hypernetted-chain approach that leads to a very high accuracy\nlevel in terms of static correlations and thermodynamics.",
        "positive": "Orientational Ordering of Passivating Ligands on CdS Nanorods in\n  Solution Generates Strong Rod-Rod Interactions: We present the first nearly atomistic molecular dynamics study of\nnanorod-nanorod association in explicit solvent, showing that inter-rod forces\ncan be dominated by microscopic factors absent in common continuum\ndescriptions. Specifically, we find that alkane ligands on faceted CdS nanorods\nin n-hexane undergo a temperature-dependent order-disorder transition akin to\nthat of self-assembled monolayers on macroscopic substrates. This collective\nligand alignment organizes nearby solvent molecules, strongly influencing the\nstatistics of rod-rod separation. The strong temperature-dependence of this\nmechanism could be exploited in the laboratory to manipulate and optimize the\nassembly of ordered structures."
    },
    {
        "anchor": "Static and dynamic properties of the interface between a polymer brush\n  and a melt of identical chains: Molecular dynamics simulations of a short-chain polymer melt between two\nbrush-covered surfaces under shear have been performed. The end-grafted\npolymers which constitute the brush have the same chemical properties as the\nfree chains in the melt and provide a soft deformable substrate. Polymer chains\nare described by a coarse-grained bead-spring model with Lennard-Jones\ninteractions between the beads and a FENE potential between nearest neighbors\nalong the backbone of the chains. The grafting density of the brush layer\noffers a way of controlling the behavior of the surface without altering the\nmolecular interactions. We perform equilibrium and non-equilibrium Molecular\nDynamics simulations at constant temperature and volume using the Dissipative\nParticle Dynamics thermostat. The equilibrium density profiles and the behavior\nunder shear are studied as well as the interdigitation of the melt into the\nbrush, the orientation on different length scales (bond vectors, radius of\ngyration, and end-to-end vector) of free and grafted chains, and velocity\nprofiles. The viscosity and slippage at the interface are calculated as\nfunctions of grafting density and shear velocity.",
        "positive": "Critical exponents for random knots: The size of a zero thickness (no excluded volume) polymer ring is shown to\nscale with chain length $N$ in the same way as the size of the excluded volume\n(self-avoiding) linear polymer, as $N^{\\nu}$, where $\\nu \\approx 0.588$. The\nconsequences of that fact are examined, including sizes of trivial and\nnon-trivial knots."
    },
    {
        "anchor": "Magnetic Resonance Imaging study of sheared granular matter: We introduce a Magnetic Resonance Imaging technique to study the geometry of\nshear zones of soft, low-frictional and hard, frictional granular materials and\ntheir mixtures. Hydrogel spheres serve as the soft, low-frictional material\ncomponent, while mustard seeds represent rigid, frictional grains. Some of the\nhydrogel spheres are doped with CuSO4 salt to serve as tracers. A split-bottom\nshear cell is sheared stepwise and the shear profiles are determined from the\ndifferences of tomograms after successive shear steps, using Particle Imaging\nVelocimetry.We find that the shear zone geometry differs considerably between\nsoft grains submersed in water and the same material without the embedding\nfluid.",
        "positive": "Microscopic model for spreading of a two-dimensional monolayer: We study the behavior of a monolayer, which occupies initially a bounded\nregion on an ideal crystalline surface and then evolves in time due to random\nhopping motion of the monolayer particles. In the case when the initially\noccupied region is the half-plane $X \\leq 0$, we determine explicitly, in terms\nof an analytically solvable mean-field-type approximation, the mean\ndisplacement $X(t)$ of the monolayer edge. We find that $X(t) \\approx A\n\\sqrt{D_{0} t}$, in which law $D_{0}$ denotes the bare diffusion coefficient\nand the prefactor $A$ is a function of the temperature and of the\nparticle-particle interactions parameters. We show that $A$ can be greater,\nequal or less than zero, and specify the critical parameter which distinguishes\nbetween the regimes of spreading ($A > 0)$, partial wetting ($A = 0$) and\ndewetting ($A < 0$)."
    },
    {
        "anchor": "Scaling of relaxation and excess entropy in plastically deformed\n  amorphous solids: When stressed sufficiently, solid materials yield and deform plastically via\nreorganization of microscopic constituents. Indeed, it is possible to alter the\nmicro-structure of materials by judicious application of stress, an empirical\npro- cess utilized in practice to enhance the mechanical properties of metals.\nUn- derstanding the interdependence of plastic flow and microscopic structure\nin these non-equilibrium states, however, remains a major challenge. Here, we\nex- perimentally investigate this relationship, between the relaxation dynamics\nand microscopic structure of disordered colloidal solids during plastic\ndeformation. We apply oscillatory shear to solid colloidal monolayers and study\ntheir particle trajectories as a function of shear rate in the plastic regime.\nUnder these cir- cumstances, the strain rate, the relaxation rate associated\nwith plastic flow, and the sample microscopic structure oscillate together but\nwith different phases. Interestingly, the experiments reveal that the\nrelaxation rate associated with plastic flow at time t is correlated with the\nstrain rate and sample microscopic structure measured at earlier and later\ntimes, respectively. The relaxation rate, in this non-stationary condition,\nexhibits power-law shear-thinning behavior and scales exponentially with sample\nexcess entropy. Thus, measurement of sample static structure (excess entropy)\nprovides insight about both strain-rate and constituent rearrangement dynamics\nin the sample at earlier times.",
        "positive": "Stochastic dynamics of adhesion catch-slip bond cluster: We present a general stochastic dynamic model of a cluster of biological\ncomplexes with fluctuating dissociation and association rates. The master\nequation has analytical solutions in two limiting cases: the vanishing force\nwith reflecting boundary condition and slow reaction limit. In particular, the\nlatter can describe the dynamics of a catch-slip bond cluster under a constant\nforce. We find that if the rebinding rate vanishes, the size of the cluster\nmatters little to the cluster lifetime within the whole catch force regime. The\nlarge cluster rapidly decays and single catch bond governs the final dynamic\nbehaviors of the cluster. The catch behavior would be further amplified in the\npresence of large nonvanishing rebinding rates."
    },
    {
        "anchor": "Structural Characterization of Many-Particle Systems on Approach to\n  Hyperuniform States: We explore quantitative descriptors that herald when a many-particle system\nin $d$-dimensional Euclidean space $\\mathbb{R}^d$ approaches a hyperuniform\nstate as a function of the relevant control parameter. We establish\nquantitative criteria to ascertain the extent of hyperuniform and\nnonhyperuniform distance-scaling regimes n terms of the ratio $B/A$, where $A$\nis \"volume\" coefficient and $B$ is \"surface-area\" coefficient associated with\nthe local number variance $\\sigma^2(R)$ for a spherical window of radius $R$.\nTo complement the known direct-space representation of the coefficient $B$ in\nterms of the total correlation function $h({\\bf r})$, we derive its\ncorresponding Fourier representation in terms of the structure factor $S({\\bf\nk})$, which is especially useful when scattering information is available\nexperimentally or theoretically. We show that the free-volume theory of the\npressure of equilibrium packings of identical hard spheres that approach a\nstrictly jammed state either along the stable crystal or metastable disordered\nbranch dictates that such end states be exactly hyperuniform. Using the ratio\n$B/A$, the hyperuniformity index $H$ and the direct-correlation function length\nscale $\\xi_c$, we study three different exactly solvable models as a function\nof the relevant control parameter, either density or temperature, with end\nstates that are perfectly hyperuniform. We analyze equilibrium hard rods and\n\"sticky\" hard-sphere systems in arbitrary space dimension $d$ as a function of\ndensity. We also examine low-temperature excited states of many-particle\nsystems interacting with \"stealthy\" long-ranged pair interactions as the\ntemperature tends to zero. The capacity to identify hyperuniform scaling\nregimes should be particularly useful in analyzing experimentally- or\ncomputationally-generated samples that are necessarily of finite size.",
        "positive": "Resummed Green-Kubo relations for a fluctuating fluid-particle model: A recently introduced stochastic model for fluid flow can be made Galilean\ninvariant by introducing a random shift of the computational grid before\ncollisions. This grid shifting procedure accelerates momentum transfer between\ncells and leads to a collisional contribution to transport coefficients. By\nresumming the Green-Kubo relations derived in a previous paper, it is shown\nthat this collisional contribution to the transport coefficients can be\ndetermined exactly. The resummed Green-Kubo relations also show that there are\nno mixed kinetic-collisional contributions to the transport coefficients. The\nleading correlation corrections to the transport coefficients are discussed,\nand explicit expressions for the transport coefficients are presented and\ncompared with simulation data."
    },
    {
        "anchor": "Three-dimensional imaging of colloidal glasses under steady shear: Using fast confocal microscopy we image the three-dimensional dynamics of\nparticles in a yielded hard-sphere colloidal glass under steady shear. The\nstructural relaxation, observed in regions with uniform shear, is nearly\nisotropic but is distinctly different from that of quiescent metastable\ncolloidal fluids. The inverse relaxation time $\\tau_\\alpha^{-1}$ and diffusion\nconstant $D$, as functions of the {\\it local} shear rate $\\dot{\\gamma}$, show\nmarked shear thinning with $\\tau_\\alpha^{-1} \\propto D \\propto\n\\dot{\\gamma}^{0.8}$ over more than two decades in $\\dot{\\gamma}$. In contrast,\nthe {\\it global} rheology of the system displays Herschel-Bulkley behavior. We\ndiscuss the possible role of large scale shear localization and other\nmechanisms in generating this difference.",
        "positive": "The evolution of the structure and mechanical properties of fully\n  bioresorbable polymer-glass composites during degradation: Fully bioresorbable polymer matrix composites have long been considered as\npotential orthopaedic implant materials, however their combination of\nmechanical strength, stiffness, ductility and bioresorbability is also\nattractive for cardiac stent applications. This work investigated reinforcement\nof polylactide-based polymers with phosphate glasses, addressing key drawbacks\nof current polymer stents, and examined the often-neglected evolution of\nstructure and mechanical properties during degradation. Incorporation of 15 -\n30wt.% phosphate glass led to modulus increases of up to 80% under simulated\nbody conditions, and 15wt.% glass composites retained comparable ductility to\npure polymers, crucial for stent applications where ductility and stiffness are\nrequired. Two-stage degradation was observed, dominated by interfacial water\nabsorption and glass dissolution. Polymer embrittlement mechanisms\n(crystallisation, enthalpy relaxation) were suppressed by glass addition,\nallowing composites to achieve a more controlled loss of mechanical properties\nduring degradation, which could allow gradual transfer of loading to newly\nhealed tissue. These results provide a valuable new system for understanding\nthe structural and mechanical changes occurring during degradation of fully\nbioresorbable polymer matrix composites, providing important new data to\nunderpin the design of effective cardiac stent materials."
    },
    {
        "anchor": "Switching hydrodynamics in multi-domain, twisted nematic, liquid crystal\n  devices: We study the switching dynamics in two-domain and four-domain twisted nematic\nliquid crystal devices. The equilibrium configuration of these devices involves\nthe coexistence of regions characterised by different handedness of the\ninherent director twist. At the boundaries between these regions there are\ntypically disclinations lines. The dynamics of the disclination lines controls\nthe properties, and in particular the switching speed, of the devices. We\ndescribe their motion using a numerical solution of the Beris-Edwards equations\nof liquid crystal hydrodynamics. Hence we are able to explain why a\nconventional two-domain device switches off slowly and to propose a device\ndesign which circumvents this problem. We also explain the patterns of\ndisclination creation and annihilation that lead to switching in the\nfour-domain twisted nematic device.",
        "positive": "Polymer translocation across a corrugated channel: Fick-Jacobs\n  approximation extended beyond the mean first passage time: Polymer translocation across a corrugated channel is a paradigmatic\nstochastic process encountered in diverse systems.\n  The instance of time when a polymer first arrives to some prescribed location\ndefines an important characteristic time scale for various phenomena, which are\ntriggered or controlled by such an event.\n  Here we discuss the translocation dynamics of a Gaussian polymer in a\nperiodically-corrugated channel using an appropriately generalized Fick-Jacobs\napproach.\n  Our main aim is to probe an effective broadness of the first passage time\ndistribution (FPTD), by determining the so-called coefficient of variation\n$\\gamma$ of the FPTD, defined as the ratio of the standard deviation versus the\nmean first passage time (MFPT).\n  We present a systematic analysis of $\\gamma$ as a function of a variety of\nsystem's parameters. We show that $\\gamma$ never significantly drops below 1\nand, in fact, can attain very large values, implying that the MFPT alone cannot\ncharacterize the first-passage statistics of the translocation process\nexhaustively well."
    },
    {
        "anchor": "Acoustic measurement of a granular density of modes: In glasses and other disordered materials, measurements of the vibrational\ndensity of states reveal that an excess number of long-wavelength\n(low-frequency) modes, as compared to the Debye scaling seen in crystalline\nmaterials, is associated with a loss of mechanical rigidity. In this paper, we\npresent a novel technique for measuring the density of modes (DOM) in a real\ngranular material, in which we mimic thermal excitations using white noise\nacoustic waves. The resulting vibrations are detected with piezoelectric\nsensors embedded inside a subset of the particles, from which we are able to\ncompute the DOM via the spectrum of the velocity autocorrelation function, a\ntechnique previously applied in thermal systems. The velocity distribution for\nindividual particles is observed to be Gaussian, but the ensemble distribution\nis non-Gaussian due to varying widths of the individual distributions. In spite\nof this deviation from a true thermal system, we find that the DOM exhibits\nseveral thermal-like features, including Debye scaling in a compressed\nhexagonally ordered packing, and an increase in low-frequency modes as the\nconfining pressure is decreased. In disordered packings, we find that a\ncharacteristic frequency $f_c$ increases with pressure, but more weakly than\nhas been observed in simulations of frictionless packings.",
        "positive": "Extreme self-organization in networks constructed from gene expression\n  data: We study networks constructed from gene expression data obtained from many\ntypes of cancers. The networks are constructed by connecting vertices that\nbelong to each others' list of K-nearest-neighbors, with K being an a priori\nselected non-negative integer. We introduce an order parameter for\ncharacterizing the homogeneity of the networks. On minimizing the order\nparameter with respect to K, degree distribution of the networks shows\npower-law behavior in the tails with an exponent of unity. Analysis of the\neigenvalue spectrum of the networks confirms the presence of the power-law and\nsmall-world behavior. We discuss the significance of these findings in the\ncontext of evolutionary biological processes."
    },
    {
        "anchor": "Crystallization Kinetics of Colloidal Spheres under Stationary Shear\n  Flow: A systematic experimental study of dispersions of charged colloidal spheres\nis presented on the effect of steady shear flow on nucleation and\ncrystal-growth rates. In addition, the non-equilibrium phase diagram as far as\nthe melting line is concerned is measured. Shear flow is found to strongly\naffect induction times, crystal growth rates and the location of the melting\nline. The main findings are that (i) the crystal growth rate for a given\nconcentration exhibits a maximum as a function of the shear rate, (ii) contrary\nto the monotonous increase of the growth rate with increasing concentration in\nthe absence of flow, a maximum of the crystal growth rate as a function of\nconcentration is observed for sheared systems, and (iii) the induction time for\na given concentration exhibits a maximum as a function of the shear rate. These\nfindings will be partly explained on a qualitative level.",
        "positive": "Effect of shear flow on the transverse thermal conductivity of polymer\n  melts: The effect of shear flows on the thermal conductivity of polymer melts is\ninvestigated using a reversed nonequilibrium molecular dynamics (RNEMD) method.\nWe extended the original RNEMD method to simultaneously produce spatial\ngradients of temperature and flow velocity in a single direction. This method\nenables the accurate measurement of thermal conductivity in the transverse\ndirection to shear flow.\n  Our main finding is that the stress-thermal rule (STR) (i.e., the linear\nrelationship between anisotropic parts of the stress tensor and the thermal\nconductivity tensor) holds for entangled polymer melts even under shear flows\nbut not for unentangled polymer melts. Furthermore, once entanglements form in\npolymer chains, the coefficient of the STR (i.e., the stress-thermal\ncoefficient) remains independent of the polymer chain length.\n  These observations align with the theoretical foundation of the STR, which\nfocuses on energy transmission along the network structure of entangled polymer\nchains [Brule, Rheol. Acta \\textbf{28}, 257 (1989)]. However, under driven\nshear flows, the stress-thermal coefficient is notably smaller than that\nmeasured in the literature for a quasi-quiescent state without external forces.\nAlthough the mechanism of the STR in shear flows has yet to be fully\nelucidated, our study confirmed the validity of the STR in shear flows. This\nallows us to use the STR as a constitutive equation for computational\nthermo-fluid dynamics of polymer melts, thus offering broad engineering\napplications."
    },
    {
        "anchor": "Investigation of Soft and Living Matter using a Micro-Extensional\n  Rheometer: Rheological properties of a material often require to be probed under\nextensional deformation. Examples include fibrous materials such as\nspider-silk, high-molecular weight polymer melts, and the contractile response\nof living cells. Such materials have strong molecular-level anisotropies which\nare either inherent or are induced by an imposed extension. However, unlike\nshear rheology, which is well-established, techniques to perform extensional\nrheology are currently under development and setups are often custom-designed\nfor the problem under study. In this article, we present a versatile device\nthat can be used to conduct extensional deformation studies of samples at\nmicroscopic scales with simultaneous imaging. We discuss the operational\nfeatures of this device and present a number of applications.",
        "positive": "Rotational microrheology of Maxwell fluids using micron-sized wires: We demonstrate a simple method for rotational microrheology in complex\nfluids, using micrometric wires. The three-dimensional rotational Brownian\nmotion of the wires suspended in Maxwell fluids is measured from their\nprojection on the focal plane of a microscope. We analyze the mean-squared\nangular displacement of the wires of length between 1 and 40 microns. The\nviscoelastic properties of the suspending fluids are extracted from this\nanalysis and found to be in good agreement with macrorheology data. Viscosities\nof simple and complex fluids between 0.01 and 30 Pa.s could be measured. As for\nthe elastic modulus, values up to ~ 5 Pa could be determined. This simple\ntechnique, allowing for a broad range of probed length scales, opens new\nperspectives in microrheology of heterogeneous materials such as gels, glasses\nand cells."
    },
    {
        "anchor": "Entropy-driven impurity-induced nematic-isotropic transition of liquid\n  crystals: Phase behavior of liquid crystals is of long-standing interest due to\nnumerous applications, with one of the key issues being how the presence of\nimpurities affects the liquid crystalline order. Here we study the\norientational order of 4-cyano-4$^{'}$-pentylbiphenyl (5CB) and\n4-cyano-4$^{'}$-hexylbiphenyl (6CB) nematic liquid crystals in the presence of\nvarying concentrations of water and n-hexane molecules serving as impurities,\nby carrying out both fully atomistic simulations and experiments. Our results\nreveal that mixing of the impurities (in case of hexane) with the host liquid\ncrystals causes a nematic-to-isotropic phase transition with hexane\nconcentration as the control parameter while demixing (in case of water)\nresults in only weak impurity-induced perturbations to the nematic\nliquid-crystalline order. We develop a coarse-grained model illustrating the\ngeneral nature and entropic origin of the mixing-induced phase transition.",
        "positive": "Behavior of nanoparticle clouds around a magnetized microsphere under\n  magnetic and flow fields: When a micron-sized magnetizable particle is introduced into a suspension of\nnanosized magnetic particles, the nanoparticles accumulate around the\nmicroparticle and form thick anisotropic clouds extended in the direction of\nthe applied magnetic field. This phenomenon promotes colloidal stabilization of\nbimodal magnetic suspensions and allows efficient magnetic separation of\nnanoparticles used in bioanalysis and water purification. In the present work,\nsize and shape of nanoparticle clouds under the simultaneous action of an\nexternal uniform magnetic field and the flow have been studied in details. In\nexperiments, dilute suspension of iron oxide nanoclusters (of a mean diameter\nof 60 nm) was pushed through a thin slit channel with the nickel microspheres\n(of a mean diameter of 50$\\mu$m) attached to the channel wall. The behavior of\nnanocluster clouds was observed in the steady state using an optical\nmicroscope. In the presence of strong enough flow, the size of the clouds\nmonotonically decreases with increasing flow speed in both longitudinal and\ntransverse magnetic fields. This is qualitatively explained by enhancement of\nhydrodynamic forces washing the nanoclusters away from the clouds. In the\nlongitudinal field, the flow induces asymmetry of the front and the back\nclouds. To explain the flow and the field effects on the clouds, we have\ndeveloped a simple model based on the balance of the stresses and particle\nfluxes on the cloud surface. This model, applied to the case of the magnetic\nfield parallel to the flow, captures reasonably well the flow effect on the\nsize and shape of the cloud and reveals that the only dimensionless parameter\ngoverning the cloud size is the ratio of hydrodynamic-to-magnetic forces - the\nMason number. At strong magnetic interactions considered in the present work\n(dipolar coupling parameter $\\alpha \\geq 2$), the Brownian motion seems not to\naffect the cloud behavior."
    },
    {
        "anchor": "Relaxation in yield stress systems through elastically interacting\n  activated events: We study consequences of long-range elasticity in thermally assisted dynamics\nof yield stress materials. Within a two-dimensinal mesoscopic model we\ncalculate the mean-square displacement and the dynamical structure factor for\ntracer particle trajectories. The ballistic regime at short time scales is\nassociated with a compressed exponential decay in the dynamical structure\nfactor, followed by a subdiffusive crossover prior to the onset of diffusion.\nWe relate this crossover to spatiotemporal correlations and thus go beyond\nestablished mean field predictions.",
        "positive": "On the accuracy of one-way approximate models for nonlinear waves in\n  soft solids: Simple strain-rate viscoelasticity models of isotropic soft solid are\nintroduced. The constitutive equations account for finite strain,\nincompressibility, material frame-indifference, nonlinear elasticity, and\nviscous dissipation. A nonlinear viscous wave equation for the shear strain is\nobtained exactly, and corresponding one-way Burgers-type equations are derived\nby making standard approximations. Analysis of the travelling wave solutions\nshows that these partial differential equations produce distinct solutions, and\nthat deviations are exacerbated when wave amplitudes are not arbitrarily small.\nIn the elastic limit, the one-way approximate wave equation can be linked to\nsimple wave theory and shock wave theory, thus allowing direct error\nmeasurements."
    },
    {
        "anchor": "Superhydrophobicity on hairy surfaces: We investigate the wetting properties of surfaces patterned with fine elastic\nhairs, with an emphasis on identifying superhydrophobic states on hydrophilic\nhairs. We formulate a two dimensional model of a large drop in contact with a\nrow of equispaced elastic hairs and, by minimising the free energy of the\nmodel, identify the stable and metastable states. In particular we concentrate\non \"partially suspended\" states, where the hairs bend to support the drop --\nsinglet states where all hairs bend in the same direction, and doublet states\nwhere neighbouring hairs bend in opposite directions -- and find the limits of\nstability of these configurations in terms of material contact angle, hair\nflexibility, and system geometry. The drop can remain suspended in a singlet\nstate at hydrophilic contact angles, but doublets exist only when the hairs are\nhydrophobic. The system is more likely to evolve into a singlet state if the\nhairs are inclined at the root. We discuss how, under limited circumstances,\nthe results can be modified to describe an array of hairs in three dimensions.\nWe find that now both singlets and doublets can exhibit superhydrophobic\nbehaviour on hydrophilic hairs. We discuss the limitations of our approach and\nthe directions for future work.",
        "positive": "The equilibrium structure of self-assembled protein nano-cages: Understanding how highly symmetric, robust, monodisperse protein cages\nself-assemble can have major applications in various areas of\nbio-nanotechnology, such as drug delivery, biomedical imaging and gene therapy.\nWe develop a model to investigate the assembly of protein subunits into the\nstructures with different size and symmetry. Using Monte Carlo simulation, we\nobtain the global minimum energy structures. Our results suggest that the\nphysical properties of building blocks including the spontaneous curvature,\nflexibility and bending rigidity of coat proteins are sufficient to predict the\nsize of the assembly products and that the symmetry and shape selectivity of\nnano-cages can be explained, at least in part, on a thermodynamic basis. The\npolymorphism of nano-cages observed in vitro assembly experiments are also\ndiscussed."
    },
    {
        "anchor": "Osmotic stress and pore nucleation in charged biological nanoshells and\n  capsids: A model system is proposed to investigate the chemical equilibrium and\nmechanical stability of biological spherical-like nanoshells in contact with an\naqueous solution with added dissociated electrolyte of a given concentration.\nThe ionic chemical equilibrium across the permeable shell is investigated in\nthe framework of an accurate Density Functional Theory (DFT) that incorporates\nelectrostatic and hardcore correlations beyond the traditional mean-field ({\\it\ne. g.}, Poisson-Boltzmann) limit. The accuracy of the theory is tested by a\ndirect comparison with Monte Carlo (MC) simulations. A simple analytical\nexpression is then deduced which clearly highlights the entropic,\nelectrostatic, and self-energy contributions to the osmotic stress over the\nshell in terms of the calculated ionic profiles. By invoking a continuum\nmean-field elastic approach to account for the shell surface stress upon\nosmotic stretching, the mechanical equilibrium properties of the shell under a\nwide variety of ionic strengths and surface charges are investigated. The model\nis further coupled to a continuum mechanical approach similar in structure to a\nClassical Nucleation Theory (CNT) to address the question of mechanical\nstability of the shells against a pore nucleation. This allows us to construct\na phase diagram which delimits the mechanical stability of capsids for\ndifferent ionic strengths and shell surface charges.",
        "positive": "Starting to move through a granular medium: We explore the process of initiating motion through a granular medium by\nmeasuring the force required to push a flat circular plate upward from\nunderneath the medium. In contrast to previous measurements of the drag and\npenetration forces, which were conducted during steady state motion, the\ninitiation force has a robust dependence on the diameter of the grains in the\nmedium. We attribute this dependence to the requirement for local dilation of\nthe grains around the circumference of the plate, as evidenced by an observed\nlinear dependence of the initiation force on the plate diameter."
    },
    {
        "anchor": "Hydration lubrication of polyzwitterionic brushes leads to nearly\n  friction- and adhesion-free droplet motion: Recently, there has been much progress in the design and application of\noil-repellent superoleophobic surfaces. Polyzwitterionic brush surfaces are of\nparticular interest, because of their ability to repel oil under water, even in\nthe absence of micro-/nano-structures. The origin of this underwater\nsuperoleophobicity is attributed to the presence of a stable water film beneath\nthe oil droplet, but this had not been demonstrated experimentally. Here, using\noptical interferometric techniques, we show that an oil droplet effectively\nhydroplanes over a water film, whose thickness is between one hundred and\nhundreds of nanometres. In addition, using a custom-built Droplet Force\nApparatus, we measured the friction and adhesion forces to be in the nN range\nfor millimetric-sized droplets. These forces are much lower than for other\nclasses of well-known liquid-repellent surfaces, including the lotus-effect and\nlubricant-infused surfaces, where the typical force is on the order of $\\mu$N",
        "positive": "Origami launcher: The article studies the elastic and locomotive properties of Miura-ori-type\npaper origami. The mechanics of a single paper crease is studied\nexperimentally, and its non-elastic properties turn out to be crucial. The\nentire origami construction is then described as a collection of individual\ncreases, its capability to launch small objects is evaluated, and the equation\nof motion is found. Thus, the height of the launched ball is studied\ntheoretically and experimentally as a function of governing parameters."
    },
    {
        "anchor": "Pickering emulsions stabilized by oppositely charged colloids: stability\n  and pattern formation: Binary mixture of oppositely charged of colloids can be used to stabilize\nwater-in-oil or oil-in-water emulsions. A Monte Carlo simulation study to\naddress the effect of charge ratio of colloids on the stability of Pickering\nemulsions is presented. The colloidal particles at the interface are modeled as\naligned dipolar hard spheres, with attractive interactions between\nunlike-charged and repulsive interaction between like-charged particles. The\noptimum composition (fraction of positively charged particles) required for the\nstabilization corresponds to a minimum in the interaction energy per particle.\nIn addition, for each charge ratio, there is a range of compositions where\nemulsions can be stabilized. The structural arrangement of particles or the\npattern formation at the emulsion interface is strongly influenced by the\ncharge ratio. We find well-mixed isotropic, square and hexagonal arrangement of\nparticles on emulsion surface for different compositions at a given charge\nratio. Distribution of coordination numbers is calculated to characterize\nstructural features. The simulation study is useful for rational design of\nPickering emulsifications wherein oppositely charged colloids are used, and for\nthe control of pattern formation that can be useful for the synthesis of\ncolloidosomes and porous-shells derived from thereof.",
        "positive": "Flow of asymmetric elongated particles: Shear induced orientational ordering of asymmetric elongated particles is\ninvestigated experimentally. Corn grains and pegs with one end sharpened are\nstudied using X-ray Computed Tomography (CT) during quasistatic shearing and\nsilo discharge. We show that asymmetries can be detected in the orientational\ndistributions of the particles, which are related to the modulated rotation of\nthe particles during shear flow. Namely, when the particles rotate in a plane\nthat is not horizontal, they spend more time with the sharper (lighter) end\npointing up, which can be explained using energetic arguments. We quantify the\nresulting asymmetry of the orientational distribution in a split bottom Couette\ncell and in a silo discharge process."
    },
    {
        "anchor": "The Plateau-Rayleigh instability in solids is a simple phase separation: A long elastic cylinder, radius $a$ and shear-modulus $\\mu$, becomes unstable\ngiven sufficient surface tension $\\gamma$. We show this instability can be\nsimply understood by considering the energy, $E(\\lambda)$, of such a cylinder\nsubject to a homogenous longitudinal stretch $\\lambda$. Although $E(\\lambda)$\nhas a unique minimum, if surface tension is sufficient\n($\\Gamma\\equiv\\gamma/(a\\mu)>\\sqrt{32}$) it looses convexity in a finite region.\nWe use a Maxwell construction to show that, if stretched into this region, the\ncylinder will phase separate into two segments with different stretches\n$\\lambda_1$ and $\\lambda_2$. Our model thus explains why the instability has\ninfinite wavelength, and allows us to calculate the instability's sub-critical\nhysteresis loop (as a function of imposed stretch), showing that instability\nproceeds with constant amplitude and at constant (positive) tension as the\ncylinder is stretched between $\\lambda_1$ and $\\lambda_2$. We use full\nnonlinear finite-element calculations to verify these predictions, and to\ncharacterize the interface between the two phases. Near $\\Gamma=\\sqrt{32}$ the\nlength of such an interface diverges introducing a new length-scale and\nallowing us to construct a 1-D effective theory. This treatment yields an\nanalytic expression for the interface itself, revealing its characteristic\nlength grows as $l_{wall}\\sim a/\\sqrt{\\Gamma-\\sqrt{32}}$.",
        "positive": "Thermodynamic Equivalence of Cyclic Shear and Deep Cooling in\n  Glass-Formers: The extreme slowing down associated with glass formation in experiments and\nin simulations results in serious difficulties to prepare deeply quenched, well\nannealed, glassy material. Recently, methods to achieve such deep quenching\nwere proposed, including vapor deposition on the experimental side and \"Swap\nMonte Carlo\" and oscillatory shearing on the simulation side. The relation\nbetween the resulting glasses under different protocols remains unclear. Here\nwe show that oscillatory shear and \"Swap Monte Carlo\" result in\nthermodynamically equivalent glasses sharing the same statistical mechanics and\nsimilar mechanical responses under external strain."
    },
    {
        "anchor": "Geometrical complexity of conformations of ring polymers under\n  topological constraints: One measure of geometrical complexity of a spatial curve is the number of\ncrossings in a planar projection of the curve.\n  For $N$-noded ring polymers with a fixed knot type, we evaluate numerically\nthe average of the crossing number over some directions. We find that the\naverage crossing number under the topological constraint are less than that of\nno topological constraint for large $N$. The decrease of the geometrical\ncomplexity is significant when the thickness of polymers is small.\n  The simulation with or without a topological constraint also shows that the\naverage crossing number and the average size of ring polymers are independent\nmeasures of conformational complexity.",
        "positive": "Viscosity critical behaviour at the gel point in a 3d lattice model: Within a recently introduced model based on the bond-fluctuation dynamics we\nstudy the viscoelastic behaviour of a polymer solution at the gelation\nthreshold. We here present the results of the numerical simulation of the model\non a cubic lattice: the percolation transition, the diffusion properties and\nthe time autocorrelation functions have been studied. From both the diffusion\ncoefficients and the relaxation times critical behaviour a critical exponent k\nfor the viscosity coefficient has been extracted: the two results are\ncomparable within the errors and are in close agreement with the Rouse model\nprediction and with some experimental results. In the critical region below the\ntransition threshold the time autocorrelation functions show a long time tail\nwhich is well fitted by a stretched exponential decay."
    },
    {
        "anchor": "Three Dimensional Flow of Colloidal Glasses: Recent experiments performed on a variety of soft glassy materials have\ndemonstrated that any imposed shear flow serves to simultaneously fluidize\nthese systems in all spatial directions [Ovarlez \\textit{et al.} (2010)]. When\nprobed with a second shear flow, the viscous response of the experimental\nsystem is determined by the rate of the primary, fluidizing flow. Motivated by\nthese findings, we employ a recently developed schematic mode-coupling theory\n[Brader \\textit{et al.} (2009)] to investigate the three dimensional flow of a\ncolloidal glass, subject to a combination of simple shear and uniaxial\ncompression. Despite differences in the specific choice of superposed flow, the\nflow curves obtained show good qualitative agreement with the experimental\nfindings and recover the observed power law describing the decay of the scaled\nviscosity as a function of the dominant rate. We then proceed to perform a more\nformal analysis of our constitutive equation for different kind of `mixed'\nflows consisting of a dominant primary flow subject to a weaker perturbing\nflow. Our study provides further evidence that the theory of Brader \\textit{et\nal.} (2009) reliably describes the dynamic arrest and mechanical fluidization\nof dense particulate suspensions.",
        "positive": "Giant fluctuations and structural effects in a flocking epithelium: Epithelial cells cultured in a monolayer are very motile in isolation but\nreach a near-jammed state when mitotic division increases their number above a\ncritical threshold. We have recently shown that a monolayer can be reawakened\nby over-expression of a single protein, RAB5A, a master regulator of\nendocytosis. This reawakening of motility was explained in term of a flocking\ntransition that promotes the emergence of a large-scale collective migratory\npattern. Here we focus on the impact of this reawakening on the structural\nproperties of the monolayer. We find that the unjammed monolayer is\ncharacterised by a fluidisation at the single cell level and by enhanced\nnon-equilibrium large-scale number fluctuations at a larger length scale. Also\nwith the help of numerical simulations, we trace back the origin of these\nfluctuations to the self-propelled active nature of the constituents and to the\nexistence of a local alignment mechanism, leading to the spontaneous breaking\nof the orientational symmetry."
    },
    {
        "anchor": "Stiffness pathologies in discrete granular systems: bifurcation, neutral\n  equilibrium, and instability in the presence of kinematic constraints: The paper develops the stiffness relationship between the movements and\nforces among a system of discrete interacting grains. The approach is similar\nto that used in structural analysis, but the stiffness matrix of granular\nmaterial is inherently non-symmetric because of the geometrics of particle\ninteractions and of the frictional behavior of the contacts. Internal geometric\nconstraints are imposed by the particles' shapes, in particular, by the surface\ncurvatures of the particles at their points of contact. Moreover, the stiffness\nrelationship is incrementally non-linear, and even small assemblies require the\nanalysis of multiple stiffness branches, with each branch region being a\npointed convex cone in displacement-space. These aspects of the particle-level\nstiffness relationship gives rise to three types of micro-scale failure:\nneutral equilibrium, bifurcation and path instability, and instability of\nequilibrium. These three pathologies are defined in the context of four types\nof displacement constraints, which can be readily analyzed with certain\ngeneralized inverses. That is, instability and non-uniqueness are investigated\nin the presence of kinematic constraints. Bifurcation paths can be either\nstable or unstable, as determined with the Hill-Bazant-Petryk criterion.\nExamples of simple granular systems of three, sixteen, and sixty four disks are\nanalyzed. With each system, multiple contacts were assumed to be at the\nfriction limit. Even with these small systems, micro-scale failure is expressed\nin many different forms, with some systems having hundreds of micro-scale\nfailure modes. The examples suggest that micro-scale failure is pervasive\nwithin granular materials, with particle arrangements being in a nearly\ncontinual state of instability.",
        "positive": "Reply to Comment on: \"Are stress-free membranes really 'tensionless'?\": This is a reply to a comment on the paper arXiv:1204.2075 \"Are stress-free\nmembranes really tensionless ?\" (EPL 95,28008 (2011))."
    },
    {
        "anchor": "Topological Methods for Polymeric Materials: Characterizing the\n  Relationship Between Polymer Entanglement and Viscoelasticity: We develop topological methods for characterizing the relationship between\npolymer chain entanglement and bulk viscoelastic responses. We introduce\ngeneralized Linking Number and Writhe characteristics that are applicable to\nopen linear chains. We investigate the rheology of polymeric chains entangled\ninto weaves with varying topologies and levels of chain density. To investigate\nviscoelastic responses, we perform non-equilibrium molecular simulations over a\nrange of frequencies using sheared Lees-Edwards boundary conditions. We show\nhow our topological characteristics can be used to capture key features of the\npolymer entanglements related to the viscoelastic responses. We find there is a\nlinear relation over a significant range of frequencies between the mean\nabsolute Writhe $Wr$ and the Loss Tangent $\\tan(\\delta)$. We also find an\napproximate inverse linear relationship between the mean absolute Periodic\nLinking Number $LK_P$ and the Loss Tangent $\\tan(\\delta)$. Our results show\nsome of the ways topological methods can be used to characterize chain\nentanglements to better understand the origins of mechanical responses in\npolymeric materials.",
        "positive": "Dynamics of Vesicle Formation from Lipid Droplet: Mechanism and\n  Controllability: A coarse-grained model developed by Marrink et al. [J. Phys. Chem. B 111,\n7812 (2007)] is applied to investigate vesiculation of lipid\n[dipalmitoylphosphatidylcholine (DPPC)] droplets in water. Three kinds of\nmorphologies of micelles are found with increasing lipid droplet size. When the\ninitial lipid droplet is smaller, the equilibrium structure of the droplet is a\nspherical micelle. When the initial lipid droplet is larger, the lipid ball\nstarts to transform into a disk micelle or vesicle. The mechanism of vesicle\nformation from a lipid ball is analyzed from the self-assembly of DPPC on the\nmolecular level, and the morphological transition from disk to vesicle with\nincreasing droplet size is demonstrated. Importantly, we discover that the\ntransition point is not very sharp, and for a fixed-size lipid ball, the disk\nand vesicle appear with certain probabilities. The splitting phenomenon, i.e.,\nthe formation of a disk/vesicle structure from a lipid droplet, is explained by\napplying a hybrid model of the Helfrich membrane theory. The elastic module of\nthe DPPC bilayer and the smallest size of a lipid droplet for certain formation\nof a vesicle are successfully predicted."
    },
    {
        "anchor": "Elastic properties of cellular polypropylene films: Finite element\n  simulations and their comparison with experiments: The Young's modulus of a two-dimensional truss-like structure is simulated by\nusing the finite element method. A power-law expression is proposed for the\neffective Young's modulus of the system. The obtained numerical results are\ncompared with the experimental data of the {\\em anisotropic thin cellular\npolypropylene films}. At high solid volume fractions ($>0.4$), the average\nshape of the cells are lateral, and their dimensions have around one-to-five\nratio. As the samples are inflated further, volume fraction of the solid is\ndecreased, the average shape approach a diamond-like structure with one-to-two\nratio. In addition the effective Young's modulus of the system increases. It is\nconcluded that valuable structural information can be obtained by analyzing the\nexperimental data and the numerical simulations, which take into account the\nmaterial's micro-structural information, simultaneously.",
        "positive": "Three-Dimensional Spontaneous Flow Transition in a Homeotropic Active\n  Nematic: We study the three-dimensional spontaneous flow transition of an active\nnematic in an infinite slab geometry using a combination of numerics and\nanalytics. We show that it is determined by the interplay of two eigenmodes --\ncalled S- and D-mode -- that are unstable at the same activity threshold and\nspontaneously breaks both rotational symmetry and chiral symmetry. The onset of\nthe unstable modes is described by a non-Hermitian integro-differential\noperator, which we determine their exponential growth rates from using\nperturbation theory. The S-mode is the fastest growing. After it reaches a\nfinite amplitude, the growth of the D-mode is anisotropic, being promoted\nperpendicular to the S-mode and suppressed parallel to it, forming a steady\nstate with a full three-dimensional director field and a well-defined\nchirality. Lastly, we derive a model of the leading-order time evolution of the\nsystem close to the activity threshold."
    },
    {
        "anchor": "Short-time Rheology and Diffusion in Suspensions of Yukawa-type\n  Colloidal Particles: A comprehensive study is presented on the short-time dynamics in suspensions\nof charged colloidal spheres. The explored parameter space covers the major\npart of the fluid-state regime, with colloid concentrations extending up to the\nfreezing transition. The particles are assumed to interact directly by a\nhard-core plus screened Coulomb potential, and indirectly by solvent-mediated\nhydrodynamic interactions (HIs). By comparison with accurate accelerated\nStokesian Dynamics (ASD) simulations of the hydrodynamic function H(q), and the\nhigh-frequency viscosity, we investigate the accuracy of two fast and\neasy-to-implement analytical schemes. The first scheme, referred to as the\npairwise additive (PA) scheme, uses exact two-body hydrodynamic mobility\ntensors. It is in good agreement with the ASD simulations of H(q) and the\nhigh-frequency viscosity, for smaller volume fractions up to about 10% and 20%,\nrespectively. The second scheme is a hybrid method combining the virtues of the\n\\delta\\gamma-scheme by Beenakker and Mazur with those of the PA scheme. It\nleads to predictions in good agreement with the simulation data, for all\nconsidered concentrations, combining thus precision with computational\nefficiency. The hybrid method is used to test the accuracy of a generalized\nStokes-Einstein (GSE) relation proposed by Kholodenko and Douglas, showing its\nsevere violation in low salinity systems. For hard spheres, however, this GSE\nrelation applies decently well.",
        "positive": "Highly Parallel Acoustic Assembly of Microparticles into Well-Ordered\n  Colloidal Crystallites: The precise arrangement of microscopic objects is critical to the development\nof functional materials and ornately patterned surfaces. Here, we present an\nacoustics-based method for the rapid arrangement of microscopic particles into\norganized and programmable architectures, which are periodically spaced within\na square assembly chamber. This macroscale device employs two-dimensional bulk\nacoustic standing waves to propel particles along the base of the chamber\ntoward pressure nodes or antinodes, depending on the acoustic contrast factor\nof the particle, and is capable of simultaneously creating thousands of\nsize-limited, isotropic and anisotropic assemblies within minutes. We pair\nexperiments with Brownian dynamics simulations to model the migration kinetics\nand assembly patterns of spherical microparticles. We use these insights to\npredict and subsequently validate the onset of buckling of the assemblies into\nthree-dimensional clusters by experiments upon increasing the acoustic pressure\namplitude and the particle concentration. The simulations are also used to\ninform our experiments for the assembly of non-spherical particles, which are\nthen recovered via fluid evaporation and directly inspected by electron\nmicroscopy. This method for assembly of particles offers several notable\nadvantages over other approaches (e.g., magnetics, electrokinetics and optical\ntweezing) including simplicity, speed and scalability and can also be used in\nconcert with other such approaches for enhancing the types of assemblies\nachievable."
    },
    {
        "anchor": "Reduced-Order Computational Model for the Molecular Dynamics Simulation\n  of Entangled Polymers: We present a new reduced-order computational method for the molecular\ndynamics simulation of entangled polymer systems. The polymer chains are\nmodeled as continuous Gaussian chains. Our algorithm is based on the\napplication of the molecular dynamics simulation method to the pseudospectral\nrepresentation of the Fourier modes of the chains.",
        "positive": "Phase separation and aging dynamics of binary liquid in porous media: We employ the state-of-the-art molecular dynamics simulations to study the\nkinetics of phase separation and aging phenomena of segregating binary fluid\nmixtures imbibed in porous materials. Different random porous structures are\nconsidered to understand the effect of pore morphology on coarsening dynamics.\nWe find the effect of complex geometrical confinement resulting in the dramatic\nslowing down in the phase separation dynamics. The domain growth follows the\npower law with an exponent dependent on the porous host structure. After the\ntransient period, a crossover to a slower domain growth is observed when the\ndomain size becomes comparable to the pore size. Due to the geometric\nconfinement, the correlation function and structure factor modify to a\nnon-Porod behavior and violate the superuniversality hypothesis. The role of\nporous host structure on the nonequilibrium aging dynamics is studied\nqualitatively by computing the two-time order-parameter autocorrelation\nfunction. This quantity exhibits scaling laws with respect to the ratio of the\ndomain length at the observation time and the age of the system. We find the\nscaling laws hold good for such confined segregating fluid mixtures."
    },
    {
        "anchor": "Solvated Membrane Nanodiscoids: A Probe For The Effects Of Gaussian\n  Curvature: Several methods now exist to solvate lipid bilayer discoids at the scale of\ntens of nanometres. Due to their size, such nanodiscoids have a comparatively\nlarge boundary-to-area ratio, making them unusually well-suited to probing the\neffects of Gaussian curvature. Arguing that fluctuations in discoid size and\nshape are quenched on formation, we quantify the stability, in terms of size\nand shape, of near-solvation discoid-like flaps that are subject to thermal\nfluctuations. Using cryo-Electron Microscopy images of Styrene Maleic Acid\nstabilised discoids, we deduce that stable, saddle-like discoids (with high\nGaussian curvature) can likely be solvated from bulk lamellar ($L_\\alpha$)\nphase at moderate-to-high surface tensions ($>10^{-4}$ N/m). We then describe\nhow such tension-controlled solvation can be used for both measuring, and\nfractionating membrane components according-to, the modulus of Gaussian\nrigidity $\\bar{\\kappa}$. Opportunities for investigating the effects of\nGaussian curvature on membrane-embedded proteins, which can be co-solvated\nduring the formation process, are also discussed.",
        "positive": "Bicontinuous soft solids with a gradient in channel size designed for\n  energy storage applications: We present examples of bicontinuous interfacially jammed emulsion gels\n(\"bijels\") with a designed gradient in the channel size along the sample. These\nsamples are created by quenching binary fluids which have a gradient in\nparticle concentration along the sample, since the channel size is determined\nby the local particle concentration. A gradient in local particle concentration\nis achieved using a two-stage loading process, with different particle volume\nfractions in each stage. Confocal microscopy and image analysis were used to\nquantitatively measure the channel size of the bijels. Bijels with a gradient\nin channel size of up to 2.8%/mm have been created. Such tailored soft\nmaterials could act as templates for energy materials optimised for both high\nionic transport rates (high power) and high interfacial area (high energy\ndensity), potentially making them useful in novel energy applications."
    },
    {
        "anchor": "Jamming and the onset of granulation in a model particle system: Granulation is a ubiquitous process crucial for many products ranging from\nfood and care products to pharmaceuticals. Granulation is the process in which\na powder is mixed with a small amount of liquid (binder) to form solid\nagglomerates surrounded by air. By contrast, at low solid volume fractions\n{\\phi}, the mixing of solid and liquid produces suspensions. At intermediate\n{\\phi}, either granules or dense suspensions are produced, depending on the\napplied stress. We address the question of how and when high shear mixing can\nlead to the formation of jammed, non-flowing granules as {\\phi} is varied. In\nparticular, we measure the shear rheology of a model system - a suspension of\nglass beads with an average diameter of $\\sim$ 7 {\\mu}m - at solid volume\nfractions {\\phi} $\\gtrsim$ 0.40. We show that recent insights into the role of\ninter-particle friction in suspension rheology allow us to use flow data to\npredict some of the boundaries between different types of granulation as {\\phi}\nincreases from $\\sim$ 0.4 towards and beyond the maximum packing point of\nrandom close packing.",
        "positive": "Synergy of Topoisomerase and Structural-Maintenance-of-Chromosomes\n  Proteins Creates a Universal Pathway to Simplify Genome Topology: Topological entanglements severely interfere with important biological\nprocesses. For this reason, genomes must be kept unknotted and unlinked during\nmost of a cell cycle. Type II Topoisomerase (TopoII) enzymes play an important\nrole in this process but the precise mechanisms yielding systematic\ndisentanglement of DNA in vivo are not clear. Here we report computational\nevidence that Structural Maintenance of Chromosomes (SMC) proteins -- such as\ncohesins and condensins -- can cooperate with TopoII to establish a synergistic\nmechanism to resolve topological entanglements. SMC-driven loop extrusion (or\ndiffusion) induces the spatial localisation of essential crossings in turn\ncatalysing the simplification of knots and links by TopoII enzymes even in\ncrowded and confined conditions. The mechanism we uncover is universal in that\nit does not qualitatively depend on the specific substrate, whether DNA or\nchromatin, or on SMC processivity; we thus argue that this synergy may be at\nwork across organisms and throughout the cell cycle."
    },
    {
        "anchor": "Mesoscopic model for the fluctuating hydrodynamics of binary and ternary\n  mixtures: A recently introduced particle-based model for fluid dynamics with continuous\nvelocities is generalized to model immiscible binary mixtures. Excluded volume\ninteractions between the two components are modeled by stochastic multiparticle\ncollisions which depend on the local velocities and densities. Momentum and\nenergy are conserved locally, and entropically driven phase separation occurs\nfor high collision rates. An explicit expression for the equation of state is\nderived, and the concentration dependence of the bulk free energy is shown to\nbe the same as that of the Widom-Rowlinson model. Analytic results for the\nphase diagram are in excellent agreement with simulation data. Results for the\nline tension obtained from the analysis of the capillary wave spectrum of a\ndroplet agree with measurements based on the Laplace's equation. The\nintroduction of \"amphiphilic\" dimers makes it possible to model the phase\nbehavior and dynamics of ternary surfactant mixtures.",
        "positive": "Saffman-Delbr\u00fcck and beyond: a pointlike approach: We show that a very good analytical approximation of Saffman-Delbr\\\"uck's\n(SD) law (mobility of a bio-membrane inclusion) can be obtained easily from the\nvelocity field produced by a pointlike force in a 2D fluid embedded in a\nsolvent, by using a small wavelength cutoff of the order of the particle's\nradius~$a$. With this method, we obtain analytical generalizations of the SD\nlaw that take into account the bilayer nature of the membrane and the\nintermonolayer friction $b$. We also derive, in a calculation that consistently\ncouples the quasi-planar two-dimensional (2D) membrane flow with the 3D solvent\nflow, the correction to the SD law arising when the inclusion creates a local\nspontaneous curvature. For an inclusion spanning a flat bilayer, the SD law is\nfound to hold simply upon replacing the 2D viscosity $\\eta_2$ of the membrane\nby the sum of the monolayer viscosities, without influence of $b$ as long as\n$b$ is above a threshold in practice well below known experimental values. For\nan inclusion located in only one of the two monolayers (or adhering to one\nmonolayer), the SD law is influenced by $b$ when $b<\\eta_2/(4a^2)$. In this\ncase, the mobility can be increased by up to a factor of two, as the opposite\nmonolayer is not fully dragged by the inclusion. For an inclusion creating a\nlocal spontaneous curvature, we show that the total friction is the sum of the\nSD friction and that due to the pull-back created by the membrane deformation,\na point that was assumed without demonstration in the literature."
    },
    {
        "anchor": "Effect of dipolar moments in domain sizes of lipid bilayers and\n  monolayers: Lipid domains are found in systems such as multi-component bilayer membranes\nand single component monolayers at the air-water interface. It was shown by\nAndelman et al. (Comptes Rendus 301, 675 (1985)) and McConnell et al. (Phys.\nChem. {\\bf 91}, 6417 (1987)) that in monolayers, the size of the domains\nresults from balancing the line tension, which favors the formation of a large\nsingle circular domain, against the electrostatic cost of assembling the\ndipolar moments of the lipids. In this paper, we present an exact analytical\nexpression for the electric potential, ion distribution and electrostatic free\nenergy for different problems consisting of three different slabs with\ndifferent dielectric constants and Debye lengths, with a circular homogeneous\ndipolar density in the middle slab. From these solutions, we extend the\ncalculation of domain sizes for monolayers to include the effects of finite\nionic strength, dielectric discontinuities (or image charges) and the\npolarizability of the dipoles and further generalize the calculations to\naccount for domains in lipid bilayers. In monolayers, the size of the domains\nis dependent on the different dielectric constants but independent of ionic\nstrength. In asymmetric bilayers, where the inner and outer leaflets have\ndifferent dipolar densities, domains show a strong size dependence with ionic\nstrength, with molecular-sized domains that grow to macroscopic phase\nseparation with increasing ionic strength. We discuss the implications of the\nresults for experiments and briefly consider their relation to other two\ndimensional systems such as Wigner crystals or heteroepitaxial growth.",
        "positive": "Investigating the source of hysteresis in the Soil-Water Characteristic\n  Curve using the multiphase lattice Boltzmann method: The soil-water characteristic curve (SWCC) is the most fundamental\nrelationship in unsaturated soil mechanics, relating the amount of water in the\nsoil to the corresponding matric suction. From experimental evidence, it is\nknown that SWCC exhibits hysteresis (i.e. wetting/drying path dependence).\nVarious factors have been proposed as contributors to SWCC hysteresis,\nincluding air entrapment, contact angle hysteresis, ink-bottle effect, and\nchange of soil fabric due to swelling and shrinkage, however, the significance\nof their contribution is debated. From our pore-scale numerical simulations,\nusing the multiphase lattice Boltzmann method, we see that even when\ncontrolling for all these factors SWCC hysteresis still occurs, indicating that\nthere is some underlying source that is not accounted for in these factors. We\nfind this underlying source by comparing the liquid/gas phase distributions for\nsimulated wetting and drying experiments of 2D and 3D granular packings. We see\nthat during wetting (i.e. pore filling) many liquid bridges expand\nsimultaneously and join together to fill the pores from the smallest to the\nlargest, allowing menisci with larger radii of curvature (lower matric\nsuction). Whereas, during drying (i.e. pore emptying), only the limited\nexisting gas clusters can expand, which become constrained by the size of the\npore openings surrounding them and result in menisci with smaller radii of\ncurvature (higher matric suction)."
    },
    {
        "anchor": "Texture changes during thermal processing of food: experiments and\n  modelling: Texture is an important attribute in the quality assessment of processed food\nproducts. Youngs modulus is an indirect measure of texture. During thermal\ntreatment of hygroscopic foods, parameters such as moisture content\nsignificantly affect Youngs modulus. However, the sensitivity to these\nparameters has not yet been quantified in terms of the stress strain behaviour.\nWe have built an experimentally validated model to address this gap. This paper\npresents the stress strain behaviour and its sensitivity towards various\nparameters. Experiments are conducted with potato samples for stress strain\nbehaviour, parametric sensitivity analysis, estimation of initial and critical\nvalues of moisture content and Youngs modulus. We found that the Youngs modulus\nand the ultimate strength vary by as much as 54 percent and 29 percent\ndepending on the rate of applied strain, indicating the need for test\nstandards. Further, we propose a model to predict the local Youngs moduli as a\nfunction of moisture content, and a relationship between these and the\neffective Youngs modulus. While model results agree well for drying, they\ndeviate by as much as 16 percent from experiments for frying, indicating the\nnecessity of incorporating additional physics. We expect this work to serve as\na crucial step towards the physics based prediction modelling of local and\neffective Youngs moduli during thermal processing of food products.",
        "positive": "Bayesian Committee Machine Potential for Isothermal-Isobaric Molecular\n  Dynamics Simulations: In recent advancements in material simulations, the utilization of Sparse\nGaussian Process Regression (SGPR)-based machine learning potentials (MLPs) has\nproven to be highly successful in diverse applications such as catalysis,\nbatteries, and solar cells. In the context of isothermal and isobaric molecular\ndynamics simulations, achieving precise pressure estimates is crucial for an\naccurate understanding of the system behavior under constant pressure\nconditions. In this study, we introduce a novel kernel function designed for\nestimating the virial term, a critical component for pressure calculations in\nmaterials simulations. Our study reveals that the inclusion of a virial\nprediction in the kernel function leads to significantly improved accuracy in\ncalculating the stress of a system. We present a kernel-based ML potential that\ncan be estimated via the Bayesian Committee Machine without the need for\nadditional training. This improvement allows us to calculate the melting\ntemperature of ice through Isobaric-Isenthalpy $NpH$ molecular dynamics\nsimulations of ice-liquid coexisting phases, employing the BCM potential."
    },
    {
        "anchor": "A Bayesian Surrogate Constitutive Model to Estimate Failure Probability\n  of Rubber-Like Materials: In this study, a stochastic constitutive modeling approach for elastomeric\nmaterials is developed to consider uncertainty in material behavior and its\nprediction. This effort leads to a demonstration of the deterministic\napproaches error compared to probabilistic approaches in order to calculate the\nprobability of failure. First, the Bayesian linear regression model calibration\napproach is employed for the Carroll model representing a hyperelastic\nconstitutive model. The developed model is calibrated based on the Maximum\nLikelihood Estimation (MLE) and Maximum a Priori (MAP) estimation. Next, a\nGaussian process (GP) as a non-parametric approach is utilized to estimate the\nprobabilistic behavior of elastomeric materials. In this approach,\nhyper-parameters of the radial basis kernel in GP are calculated using L-BFGS\nmethod. To demonstrate model calibration and uncertainty propagation, these\napproaches are conducted on two experimental data sets for silicon-based and\npolyurethane-based adhesives, with four samples from each material. These\nuncertainties stem from model, measurement, to name but a few. Finally, failure\nprobability calculation analysis is conducted with First Order Reliability\nMethod (FORM) analysis and Crude Monte Carlo (CMC) simulation for these data\nsets by creating a limit state function based on the stochastic constitutive\nmodel at failure stretch. Furthermore, sensitivity analysis is used to show the\nimportance of each parameter in the probability of failure. Results show the\nperformance of the proposed approach not only for uncertainty quantification\nand model calibration but also for failure probability calculation of\nhyperelastic materials.",
        "positive": "Kinetics of fragmentation and dissociation of two-strand protein\n  filaments: Coarse-grained simulations and experiments: While a significant body of investigations have been focused on the process\nof protein self-assembly, much less is understood about the reverse process of\na filament breaking due to thermal motion into smaller fragments, or\ndepolymerization of subunits from the filament ends. Indirect evidence for\nactin and amyloid filament fragmentation has been reported, although the\nphenomenon has never been directly observed either experimentally or in\nsimulations. Here we report the direct observation of filament depolymerization\nand breakup in a minimal, calibrated model of coarse-grained molecular\nsimulation. We quantify the orders of magnitude by which the depolymerization\nrate from the filament ends $k_\\mathrm{off}$ is larger than fragmentation rate\n$k_{-}$ and establish the law $k_\\mathrm{off}/k_- = \\exp [( \\varepsilon_\\| -\n\\varepsilon_\\bot) / k_\\mathrm{B}T ] = \\exp [0.5 \\varepsilon / k_\\mathrm{B}T ]$,\nwhich accounts for the topology and energy of bonds holding the filament\ntogether. This mechanism and the order-of-magnitude predictions are well\nsupported by direct experimental measurements of depolymerization of insulin\namyloid filaments."
    },
    {
        "anchor": "Burst dynamics during drainage displacements in porous media:\n  Simulations and experiments: We investigate the burst dynamics during drainage going from low to high\ninjection rate at various fluid viscosities. The bursts are identified as\npressure drops in the pressure signal across the system. We find that the\nstatistical distribution of pressure drops scales according to other systems\nexhibiting self-organized criticality. The pressure signal was calculated by a\nnetwork model that properly simulates drainage displacements. We compare our\nresults with corresponding experiments.",
        "positive": "Bioinspired multi-asymmetric magnetized surfaces for tailoring\n  energy-free liquid manipulation and 3-DOF solid transportation: Through the utilization of smart materials and well-designed structures,\nfunctional surfaces have been developed to enable small-scale liquid/solid\nmanipulation tasks, thereby facilitating crucial applications in the fields of\nmicrofluidics, soft robotics, and biomedical engineering. However, the design\nof functional systems with flexible, tunable, and multimodal liquid/solid\nmanipulation capabilities remains a challenging endeavor. Here, inspired by\nasymmetric structural features in natural plants and metachrony in cross-scale\nbiological systems, I report a magnetic-responsive functional surface that can\nachieve rich liquid operations under static magnetic fields, while also\nenabling the transportation of solids with multiple degrees of freedom (DOFs)\nunder dynamic magnetic fields. The presence of curvature pillars on the\nsurface, combined with their magnetic-driven tilt/gradient arrangement, imparts\nliquids with multi-directional spreading modes based on the asymmetry of\nLaplace pressure. I elucidate the mechanisms governing these liquid spreading\nmodes and subsequently develop compelling liquid operations, such as adjustable\nanti-gravity climbing, spontaneous modal shifts in liquid transport, and liquid\nmixing. Furthermore, the dynamic metachronal motion of the magnetic pillars can\nbe harnessed for solid object transportation. I illustrate the\nsynchronous/asynchronous transport modes of the surface and propose a novel\nstrategy for achieving 3-DOF solid transportation by coordinating the\narrangement of objects and employing magnetic actuation strategies. This study\npresents a new design concept for application-oriented manipulation surfaces,\nwhich hold significant potential for extensive engineering applications."
    },
    {
        "anchor": "Structure and rheological properties of soft-hard nanocomposites:\n  Influence of aggregation and interfacial modification: A study of the reinforcement effect of a soft polymer matrix by hard\nnanometric filler particles is presented. In the main part of this article, the\nstructure of the silica filler in the matrix is studied by Small Angle Neutron\nScattering (SANS), and stress-strain isotherms are measured to characterize the\nrheological properties of the composites. Our analysis allows us to quantify\nthe degree of aggregation of the silica in the matrix, which is studied as a\nfunction of pH (4-10), silica volume fraction (3-15%) and silica bead size\n(average radius 78 A and 96 A). Rheological properties of the samples are\nrepresented in terms of the strain-dependent reinforcement factor, which\nhighlights the contribution of the filler. Combining the structural information\nwith a quantitative analysis of the reinforcement factor, the aggregate size\nand compacity (10%-40%) as a function of volume fraction and pH can be deduced.\nIn a second, more explorative study, the grafting of polymer chains on\nnanosilica beads for future reinforcement applications is followed by SANS. The\nstructure of the silica and the polymer are measured separately by contrast\nvariation, using deuterated material. The aggregation of the silica beads in\nsolution is found to decrease during polymerization, reaching a rather low\nfinal aggregation number (less than ten).",
        "positive": "Efficacy of self-phoretic colloids and microswimmers: Within a unified formulation, encompassing self-electrophoresis,\nself-diffusiophoresis, and self-thermophoresis, we provide a simple integral\nkernel transforming the relevant surface flux to particle velocity for any\nspheroid with axisymmetric surface activity and uniform phoretic mobility. We\ndefine efficacy, a dimensionless efficiency-like quantity expressing the speed\nresulting from unit absolute flux density on the surface, which allows a\nmeaningful comparison of the performance of different motor designs. For\nbipartite designs with piecewise uniform flux over complementary surface\nregions, the efficacy is mapped out over the entire range of geometry (discotic\nthrough sphere to rod-like) and of bipartitioning, and intermediate aspect\nratios that maximize efficacy are identified. Comparison is made to\nexperimental data from the literature."
    },
    {
        "anchor": "Universality and identity ordering in heteropolymer coil-globule\n  transition: The coil-globule transition of an energy polydisperse chain, a model\nheteropolymer system where the number of monomer species is as large as the\ntotal number of monomers, is studied by means of computer simulations. In this\nstudy, we systematically explore the consequences of having different\nfunctional form and variance of the energy distribution on the coil-globule\ntransition in general. In particular, considering Gaussian (G) and uniform (U)\ndistributions, the effect of varying polydispersity index, $\\delta$, on the\ntransition temperature $\\theta^\\ast$, chain size, internal structure and\nspatial organization of monomers in the globule, and kinetics of the folding\nare addressed. It is found that the transition temperature of the model\nheteropolymer is lower than that of the homopolymer counterpart, and\n$\\theta^\\ast$ increases with $\\delta$ (both G and U) and $\\theta^\\ast({\\rm U})\n< \\theta^\\ast({\\rm G})$ consistently. The results of our study suggest that\n$\\theta^\\ast$ is governed by the most probable value (rather than the width) of\nthe pair-wise energy distribution. Interestingly, the nature of the collapse\ntransition turns out to be universal, i.e., when scaled properly (irrespective\nof the functional form and variance) all the swelling curves fall on a master\ncurve and it is well described by the same scaling form of the homopolymer\ncounterpart. However, following quenching, the transition from coil to globule\nis relatively fast for heteropolymer (with no significant difference between G\nand U systems, and no significant $\\delta$ dependence within the considered\nrange). On the other hand, internal organization in the collapsed state,\nquantified through mean contact probability, show distinct scaling regimes.\nAlso we observe segregation of monomers based on their identities which is more\npronounced in the case of uniform distribution.",
        "positive": "Thermodiffusion in binary liquids: the role of irreversibility: We study thermal diffusion in binary mixtures in the framework of\nnon-equilibrium thermodynamics. Our formal result displays the role of partial\nenthalpies and Onsager's generalized mobilities. The mobility ratio provides a\nmeasure for the irreversible character of thermal diffusion. Comparison with\nexperimental data on benzene, cyclohexane, toluene and alkanes shows that\nirreversibility is essential for thermal diffusion, and in particular for the\nisotope effect."
    },
    {
        "anchor": "Do Machine-Learning Atomic Descriptors and Order Parameters Tell the\n  Same Story? The Case of Liquid Water: Machine-learning (ML) has become a key workhorse in molecular simulations.\nBuilding an ML model in this context, involves encoding the information of\nchemical environments using local atomic descriptors. In this work, we focus on\nthe Smooth Overlap of Atomic Positions (SOAP) and their application in studying\nthe properties of liquid water both in the bulk and at the hydrophobic\nair-water interface. By using a statistical test aimed at assessing the\nrelative information content of different distance measures defined on the same\ndata space, we investigate if these descriptors provide the same information as\nsome of the common order parameters that are used to characterize local water\nstructure such as hydrogen bonding, density or tetrahedrality to name a few.\nOur analysis suggests that the ML description and the standard order parameters\nof local water structure are not equivalent. In particular, a combination of\nthese order parameters probing local water environments can predict SOAP\nsimilarity only approximately, and viceversa, the environments that are similar\naccording to SOAP are not necessarily similar according to the standard order\nparameters. We also elucidate the role of some of the metaparameters entering\nin the SOAP definition in encoding chemical information.",
        "positive": "Controlling Chirality of Entropic Crystals: Colloidal crystal structures with complexity and diversity rivaling atomic\nand molecular crystals have been predicted and obtained for hard particles by\nentropy maximization. However, so far homochiral colloidal crystals, which are\ncandidates for photonic metamaterials, are absent. Using Monte Carlo\nsimulations we show that chiral polyhedra exhibiting weak directional entropic\nforces self-assemble either an achiral crystal or a chiral crystal with limited\ncontrol over the crystal handedness. Building blocks with stronger faceting\nexhibit higher selectivity and assemble a chiral crystal with handedness\nuniquely determined by the particle chirality. Tuning the strength of\ndirectional entropic forces by means of particle rounding or the use of\ndepletants allows for reconfiguration between achiral and homochiral crystals.\nWe rationalize our findings by quantifying the chirality strength of each\nparticle, both from particle geometry and potential of mean force and torque\ndiagrams."
    },
    {
        "anchor": "Effect of cohesion on shear banding in quasi-static granular material: It is widely recognized in particle technology that adhesive powders show a\nwide range of different bulk behavior due to the peculiarity of the particle\ninteraction. We use Discrete Element simulations to investigate the effect of\ncontact cohesion on the steady state of dense powders in a slowly sheared\nsplit-bottom Couette cell, which imposes a wide stable shear band. The\nintensity of cohesive forces can be quantified by the {\\em granular Bond\nnumber} ($Bo$), namely the ratio between maximum attractive force and average\nforce due to external compression. We find that the shear banding phenomenon is\nalmost independent of cohesion for Bond numbers $Bo<1$, but for $Bo \\ge 1$\ncohesive forces start to play an important role, as both width and center\nposition of the band increase for $Bo > 1$. Inside the shear band, the mean\nnormal contact force is always independent of cohesion and depends only on the\nconfining stress. In contrast, when the behavior is analyzed focusing on the\neigen-directions of the local strain rate tensor, a dependence on cohesion\nshows up. Forces carried by contacts along the compressive and tensile\ndirections are symmetric about the mean force (larger and smaller\nrespectively), while the force along the third, neutral direction follows the\nmean force. This anisotropy of the force network increases with cohesion, just\nlike the heterogeneity in all (compressive, tensile and neutral) directions.",
        "positive": "Pinning Dislocations in Colloidal Crystals with Active Particles that\n  Seek Stacking Faults: There is growing interest in functional, adaptive devices built from\ncolloidal subunits of micron size or smaller. A colloidal material with dynamic\nmechanical properties could facilitate such microrobotic machines. Here we\nstudy via computer simulation how active interstitial particles in small\nquantities can be used to modify the bulk mechanical properties of a colloidal\ncrystal. Passive interstitial particles are known to pin dislocations in\nmetals, thereby increasing resistance to plastic deformation. We extend this\ntactic by employing anisotropic active interstitials that travel\nsuper-diffusively and bind strongly to stacking faults associated with partial\ndislocations. We find that: 1) interstitials that are effective at reducing\nplasticity compromise between strong binding to stacking faults and high\nmobility in the crystal bulk. 2) Reorientation of active interstitials in the\ncrystal depends upon rotational transitions between high-symmetry crystal\ndirections. 3) The addition of certain active interstitial shapes at\nconcentrations as low as $60$ per million host particles ($0.006\\%$) can create\na shear threshold for dislocation migration."
    },
    {
        "anchor": "Structure of force networks in tapped particulate systems of disks and\n  pentagons (Part 1): Clusters and Loops: The force network of a granular assembly, defined by the contact network and\nthe corresponding contact forces, carries valuable information about the state\nof the packing. Simple analysis of these networks based on the distribution of\nforce strengths is rather insensitive to the changes in preparation protocols\nor to the types of particles. In this paper we consider two dimensional\nsimulations of tapped systems built from frictional disks and pentagons, and\nstudy the structure of the force networks of granular packings by considering\nnetwork's topology as force thresholds are varied. We show that the number of\nclusters and loops observed in the force networks as a function of the force\nthreshold are markedly different for disks and pentagons if the tangential\ncontact forces are considered, whereas they are surprisingly similar for the\nnetwork defined by the normal forces. In particular, the results indicate that,\noverall, the force network is more heterogeneous for disks than for pentagons.\nAdditionally, we show that the states obtained by tapping with different\nintensities that display similar packing fraction are difficult to distinguish\nbased on simple topological invariants.",
        "positive": "Patterns in Flowing Sand: Understanding the Physics of Granular Flow: Dense granular flows are often unstable and form inhomogeneous structures.\nAlthough significant advances have been recently made in understanding simple\nflows, instabilities of such flows are often not understood. We present\nexperimental and numerical results that show the formation of longitudinal\nstripes that arise from instability of the uniform flowing state of granular\nmedia on a rough inclined plane. The form of the stripes depends critically on\nthe mean density of the flow with a robust form of stripes at high density that\nconsists of fast sliding plug-like regions (stripes) on top of highly agitated\nboiling material - a configuration reminiscent of the Leidenfrost effect when a\ndroplet of liquid lifted by its vapor is hovering above a hot surface."
    },
    {
        "anchor": "Models of Synthesis of Uniform Colloids and Nanocrystals: We present modeling approaches to explain mechanisms of control of uniformity\n(narrow distribution) of sizes and shapes in synthesis of nanosize crystals and\nmicron-size colloids. We consider those situations when the nanocrystals are\nformed by burst nucleation. The colloids are then self-assembled by aggregation\nof nanocrystals. The coupled kinetic processes are both controlled by\ndiffusional transport, yielding well-defined colloid dispersions used in many\napplications. We address aspects of modeling of particle structure selection,\nranging from nucleation to growth by aggregation and to mechanisms of emergence\nof particle shapes.",
        "positive": "Giant drag reduction due to interstitial air in sand: When an object impacts onto a bed of very loose, fine sand, the drag it\nexperiences depends on the ambient pressure in a surprising way: Drag is found\nto increase significantly with decreasing pressure. We use a modified\npenetrometer experiment to investigate this effect and directly measure the\ndrag on a sphere as a function of both velocity and pressure. We observe a drag\nreduction of over 90% and trace this effect back to the presence of air in the\npores between the sand grains. Finally, we construct a model based on the\nmodification of grain-grain interactions that is in full quantitative agreement\nwith the experiments."
    },
    {
        "anchor": "Ring polymers in melts and solutions: scaling and crossover: We propose a simple mean-field theory for the structure of ring polymer\nmelts. By combining the notion of topological volume fraction and a classical\nvan der Waals theory of fluids, we take into account many body effects of\ntopological origin in dense systems. We predict that although the compact\nstatistics with the Flory exponent $\\nu=1/3$ is realized for very long chains,\nmost practical cases fall into the crossover regime with the apparent exponent\n$\\nu = 2/5$ during which the system evolves toward a topological dense-packed\nlimit.",
        "positive": "Angle-resolved effective potentials for disk-shaped molecules: We present an approach for calculating coarse-grained angle-resolved\neffective pair potentials for uniaxial molecules. For integrating out the\nintramolecular degrees of freedom we apply umbrella sampling and steered\ndynamics techniques in atomistically-resolved molecular dynamics (MD) computer\nsimulations. Throughout this study we focus on disk-like molecules such as\ncoronene. To develop the methods we focus on integrating out the van-der-Waals\nand intramolecular interactions, while electrostatic charge contributions are\nneglected. The resulting coarse-grained pair potential reveals a strong\ntemperature and angle dependence. In the next step we fit the numerical data\nwith various Gay-Berne-like potentials to be used in more efficient simulations\non larger scales. The quality of the resulting coarse-grained results is\nevaluated by comparing their pair and many-body structure as well as some\nthermodynamic quantities self-consistently to the outcome of atomistic MD\nsimulations of many-particle systems. We find that angle-resolved potentials\nare essential not only to accurately describe crystal structures but also for\nfluid systems where simple isotropic potentials start to fail already for low\nto moderate packing fractions. Further, in describing these states it is\ncrucial to take into account the pronounced temperature dependence arising in\nselected pair configurations due to bending fluctuations."
    },
    {
        "anchor": "Tension and solute depletion in multilamellar vesicles: We show that a metastable multilamellar vesicle (`onion'), in contact with\nexcess solvent, can spontaneously deplete solute molecules from its interior\nthrough an unusual, entropy-driven mechanism. Fluctuation entropy is gained as\nthe uneven partition of solute molecules helps the onion relieve tension in its\nlamellae. This mechanism accounts for recent experiments on the interaction\nbetween uncharged phospholipid onions and dissolved sugars.",
        "positive": "Hyperuniform structures formed by shearing colloidal suspensions: In periodically sheared suspensions there is a dynamical phase transition\ncharacterized by a critical strain amplitude $\\gamma_c$ between an absorbing\nstate where particle trajectories are reversible and an active state where\ntrajectories are chaotic and diffusive. Repulsive non-hydrodynamic interactions\nbetween \"colliding\" particles' surfaces have been proposed as a source of this\nbroken time reversal symmetry. A simple toy model called Random Organization\nqualitatively reproduces the dynamical features of this transition. Random\nOrganization and other absorbing state models exhibit hyperuniformity, a strong\nsuppression of density fluctuations on long length-scales quantified by a\nstructure factor $S(q \\rightarrow 0) \\sim q^\\alpha$ with $\\alpha > 0$, at\ncriticality. Here we show experimentally that the particles in periodically\nsheared suspensions organize into structures with anisotropic short-range order\nbut isotropic, long-range hyperuniform order when oscillatory shear amplitudes\napproach $\\gamma_c$."
    },
    {
        "anchor": "Symmetries and Elasticity of Nematic Gels: A nematic liquid-crystal gel is a macroscopically homogeneous elastic medium\nwith the rotational symmetry of a nematic liquid crystal. In this paper, we\ndevelop a general approach to the study of these gels that incorporates all\nunderlying symmetries. After reviewing traditional elasticity and clarifying\nthe role of broken rotational symmetries in both the reference space of points\nin the undistorted medium and the target space into which these points are\nmapped, we explore the unusual properties of nematic gels from a number of\nperspectives. We show how symmetries of nematic gels formed via spontaneous\nsymmetry breaking from an isotropic gel enforce soft elastic response\ncharacterized by the vanishing of a shear modulus and the vanishing of stress\nup to a critical value of strain along certain directions. We also study the\nphase transition from isotropic to nematic gels. In addition to being fully\nconsistent with approaches to nematic gels based on rubber elasticity, our\ndescription has the important advantages of being independent of a microscopic\nmodel, of emphasizing and clarifying the role of broken symmetries in\ndetermining elastic response, and of permitting easy incorporation of spatial\nvariations, thermal fluctuations, and gel heterogeneity, thereby allowing a\nfull statistical-mechanical treatment of these novel materials.",
        "positive": "A nano polymer aggregate on a substrate: A Theoretical study: We consider the lattice model for an ideal-linear polymer chain to mimic the\nconformations of the semi-flexible homo-polymer chain. The polymer chain is\nassumed to confine in the fairly small area, such that the flexible chain\nconformations are easily polymerized in the nano-area. It has been described\nusing analytical calculations that such a situation may lead to interesting and\ndistinct theoretical findings of the thermodynamics of semi-flexible\nhomo-polymeric macromolecules where the macromolecules are confined in the\nnano-length scale. We also discuss the characteristics of the persistent length\nand the elastic force due to the nano scale confinement of an infinitely long\nideal polymer chain."
    },
    {
        "anchor": "Microphase separation in cross-linked polymer blends: Efficient replica\n  RPA post-processing of simulation data for homopolymer networks: We investigate the behaviour of randomly cross-linked (co)polymer blends\nusing a combination of replica theory and large-scale molecular dynamics\nsimulations. In particular, we derive the analogue of the random phase\napproximation for systems with quenched disorder and show how the required\ncorrelation functions can be calculated efficiently. By post-processing\nsimulation data for homopolymer networks we are able to describe neutron\nscattering measurements in heterogeneous systems without resorting to\nmicroscopic detail and otherwise unphysical assumptions. We obtain structure\nfunction data which illustrate the expected microphase separation and contain\nsystem-specific information relating to the intrinsic length scales of our\nnetworks.",
        "positive": "To the concept of the elastic interaction: A general description of elastic matter and the long-range elastic\ninteraction is propose. The type of the far-field interaction is determined by\nthe way of breaking in the continuum distribution of the elastic field produced\nby topological defects, which can present isolated inclusions. To provide an\nadequate description of the inter-inclusion interaction. Thus we can determine\nthe size of inclusion as core topological defect in elastic field. In this\ndescription the charge in electrodynamic and mass in gravity present\npeculiarity of elastic filed and determined in term this field. The interaction\nis a direct and immediate result of the field deformation. Exist two type\ninteraction. Interaction through change the ground state of elastic matter and\ninteraction with the help of the carrier of interaction, which can present as\nsmall changing of deformations."
    },
    {
        "anchor": "Scalable 3D printing for topological mechanical metamaterials: Mechanical metamaterials are structures designed to exhibit an exotic\nresponse, such as topological soft modes at a surface. Here we explore\nsingle-material 3D prints of these topological structures by translating a\nball-and-spring model into a physical prototype. By uniaxially compressing the\n3D-printed solid having marginal rigidity, we observe that the surfaces are\nconsistently softer than the bulk. However, we also find that either of two\nopposite surfaces can be the softest, in contrast to the topologically robust\npredictions of the linear model. Finite-element simulations allow us to bridge\nthis gap. We explore how the printing geometry and deformation amplitude could\naffect surface softness. For small strains, we find qualitative agreement with\nthe ball-and-spring model but, surprisingly, nonlinear deformations can select\nwhich side is softest. Our work contextualizes the predictions of topological\nmechanics for real 3D materials and their potential for cushioning\napplications.",
        "positive": "Probing lipid membrane bending mechanics using gold nanorod tracking: Lipid bilayer membranes undergo rapid bending undulations with wavelengths\nfrom tens of nanometers to tens of microns due to thermal fluctuations. Here,\nwe probe such undulations and the membranes' mechanics by measuring the\ntime-varying orientation of single gold nanorods (GNRs) adhered to the\nmembrane, using high-speed dark field microscopy. In a lipid vesicle, such\nmeasurements allow the determination of the membrane's viscosity, bending\nrigidity and tension as well as the friction coefficient for sliding of the\nmonolayers over one another. The in-plane rotation of the GNR is hindered by\nundulations in a membrane tension dependent manner, consistent with\nsimulations. The motion of single GNRs adhered to the plasma membrane of living\ncultured cells similarly reveals that membrane's complex physics and coupling\nto the cell's actomyosin cortex."
    },
    {
        "anchor": "Short-wavelength collective modes in a binary hard-sphere mixture: We use hard-sphere generalized hydrodynamic equations to discuss the extended\nhydrodynamic modes of a binary mixture. The theory presented here is analytic\nand it provides us with a simple description of the collective excitations of a\ndense binary mixture at molecular length scales. The behavior we predict is in\nqualitative agreement with molecular-dynamics results for soft-sphere mixtures.\nThis study provides some insight into the role of compositional disorder in\nforming glassy configurations.",
        "positive": "Exact results for sheared polar active suspensions with variable liquid\n  crystalline order: We consider a confined sheared active polar liquid crystal with a uniform\norientation and study the effect of variations in the magnitude of\npolarization. Restricting our analysis to one-dimensional geometries, we\ndemonstrate that with asymmetric boundary conditions, this system is\ncharacterized, macroscopically, by a linear shear stress vs. shear strain\nrelationship that does not pass through the origin: At a zero strain rate, the\nfluid sustains a non-zero stress. Analytic solutions for the polarization,\ndensity, and velocity fields are derived for asymptotically large or small\nsystems and are shown by comparison with precise numerical solutions to be good\napproximations for finite-size systems."
    },
    {
        "anchor": "Deep learning-based computational method for soft matter dynamics: Deep\n  Onsager-Machlup method: A deep learning-based computational method has been proposed for soft matter\ndynamics -- the deep Onsager-Machlup method (DOMM), which combines the brute\nforces of deep neural networks (DNNs) with the fundamental physics principle --\nOnsager-Machlup variational principle (OMVP). In the DOMM, the trial solution\nto the dynamics is constructed by DNNs that allow us to explore a rich and\ncomplex set of admissible functions. It outperforms the Ritz-type variational\nmethod where one has to impose carefully-chosen trial functions. This\ncapability endows the DOMM with the potential to solve rather complex problems\nin soft matter dynamics that involve multiple physics with multiple slow\nvariables, multiple scales, and multiple dissipative processes. Actually, the\nDOMM can be regarded as an extension of the deep Ritz method constructed using\nvariational formulations of physics models to solve static problems in physics\nas discussed in our former work [Wang et al, Soft Matter, 2022, 18, 6015-6031].\nIn this work, as the first step, we focus on the validation of the DOMM as a\nuseful computational method by using it to solve several typical soft matter\ndynamic problems: particle diffusion in dilute solutions, and two-phase\ndynamics with and without hydrodynamics. The predicted results agree very well\nwith the analytical solution or numerical solution from traditional\ncomputational methods. These results show the accuracy and convergence of DOMM\nand justify it as an alternative computational method for solving soft matter\ndynamics.",
        "positive": "Vanishing in Fractal Space: Thermal Melting and Hydrodynamic Collapse: Fractals emerge everywhere in nature, exhibiting intricate geometric\ncomplexities through the self-organizing patterns that span across multiple\nscales. Here, we investigate beyond steady-states the interplay between this\ngeometry and the vanishing dynamics, through phase-transitional thermal melting\nand hydrodynamic void collapse, within fractional continuous models. We present\ngeneral analytical expressions for estimating vanishing times with their\napplicability contingent on the fractality of space. We apply our findings on\nthe fractal environments crucial for plant growth: natural soils. We focus on\nthe transport phenomenon of cavity shrinkage in incompressible fluid,\nconducting a numerical study beyond the inviscid limit. We reveal how a minimal\ncollapsing time can emerge through a non-trivial coupling between the fluid\nviscosity and the surface fractal dimension."
    },
    {
        "anchor": "Microstructure and Aging Dynamics of Fluorescent Nanoclay Co-gels of\n  Laponite and Montmorillonite: The phenomenon of aging in soft matter systems is an intriguing and\ninteresting. In his study we investigate the microstructure and aging dynamics\nof fluorescent nanoclay gels formed from the mixture of small (~25) and large\n(~250) aspect ratio nanodiscs using various experimental techniques. We examine\nhow the presence of one kind of clay in other clay of different nature affect\nthe aging dynamics, microstructure and the final resulting phase. Viscosity of\nthe dispersions grows as a power-law with waiting time of the system and the\ndispersions initially show Maxwellian behaviour but deviated as the time\nprogressed. Fractal dimension, df of the gels is found to be 2.5. Confocal\nmicrographs revealed clear grain boundaries in the nanoclay gels, since\nNa-Montmorillonite exhibit fluorescence. We also report for the first time that\nthe gels containing sodium MMT gives a bright green-yellow fluorescence in\nultra violet light. These fluorescent gels may be useful in industry and\nacademic research.",
        "positive": "Formation of shear-bands in drying colloidal dispersions: In directionally-dried colloidal dispersions regular bands can appear behind\nthe drying front, inclined at $\\pm45^\\circ$ to the drying line. Although these\nfeatures have been noted to share visual similarities to shear bands in metal,\nno physical mechanism for their formation has ever been suggested, until very\nrecently. Here, through microscopy of silica and polystyrene dispersions, dried\nin Hele-Shaw cells, we demonstrate that the bands are indeed associated with\nlocal shear strains. We further show how the bands form, that they scale with\nthe thickness of the drying layer, and that they are eliminated by the addition\nof salt to the drying dispersions. Finally, we reveal the origins of these\nbands in the compressive forces associated with drying, and show how they\naffect the optical properties (birefringence) of colloidal films and coatings."
    },
    {
        "anchor": "Nonlinear Force Propagation during Granular Impact: We experimentally study nonlinear force propagation into granular material\nduring impact from an intruder, and we explain our observations in terms of the\nnonlinear grain-scale force relation. Using high-speed video and photoelastic\nparticles, we determine the speed and spatial structure of the force response\njust after impact. We show that these quantities depend on a dimensionless\nparameter, $M'=t_c v_0/d$, where $v_0$ is the intruder speed at impact, $d$ is\nthe particle diameter, and $t_c$ is the collision time for a pair of grains\nimpacting at relative speed $v_0$. The experiments access a large range of $M'$\nby using particles of three different materials. When $M' \\ll 1$, force\npropagation is chain-like with a speed, $v_f$, satisfying $v_f \\propto d/t_c$.\nFor larger $M'$, the force response becomes spatially dense and the force\npropagation speed departs from $v_f\\propto d/t_c$, corresponding to collective\nstiffening of a strongly compressed packing of grains.",
        "positive": "Spontaneous Vibrations and Stochastic Resonance of Short Oligomeric\n  Springs: There is growing interest in molecular structures that exhibit dynamics\nsimilar to bistable mechanical systems. These structures have the potential to\nbe used as nanodevices with two distinct states. Particularly intriguing are\nstructures that display spontaneous vibrations and stochastic resonance.\nPreviously, through molecular dynamics simulations, it was discovered that\nshort pyridine-furan springs, when subjected to force loading, exhibit the\nbistable dynamics of a Duffing oscillator. In this study, we extend these\nsimulations to include short pyridine-pyrrole and pyridine-furan springs in a\nhydrophobic solvent. Our findings demonstrate that these systems also display\nthe bistable dynamics of a Duffing oscillator, accompanied by spontaneous\nvibrations and stochastic resonance activated by thermal noise."
    },
    {
        "anchor": "Strong coupling electrostatics for randomly charged surfaces:\n  Antifragility and effective interactions: We study the effective interaction mediated by strongly coupled Coulomb\nfluids between dielectric surfaces carrying quenched, random monopolar charges\nwith equal mean and variance, both when the Coulomb fluid consists only of\nmobile multivalent counterions and when it consists of an asymmetric ionic\nmixture containing multivalent and monovalent (salt) ions in equilibrium with\nan aqueous bulk reservoir. We analyze the consequences that follow from the\ninterplay between surface charge disorder, dielectric and salt image effects,\nand the strong electrostatic coupling that results from multivalent counterions\non the distribution of these ions and the effective interaction pressure they\nmediate between the surfaces. In a dielectrically homogeneous system, we show\nthat the multivalent counterions are attracted towards the surfaces with a\nsingular, disorder-induced potential that diverges logarithmically on approach\nto the surfaces, creating a singular counterion density profile with an\nalgebraic divergence at the surfaces. This effect drives the system towards a\nstate of lower thermal \"disorder\", one that can be described by a renormalized\ntemperature, exhibiting thus a remarkable antifragility. The interaction\npressure acting on the surfaces displays in general a highly non-monotonic\nbehavior as a function of the inter-surface separation with a prominent regime\nof attraction at small to intermediate separations. This attraction is caused\ndirectly by the combined effects from charge disorder and strong coupling\nelectrostatics of multivalent counterions, which can be quite significant even\nwith a small degree of surface charge disorder relative to the mean surface\ncharge. The strong coupling, disorder-induced attraction is typically far more\nstronger than the van der Waals interaction between the surfaces, especially\nwithin a range of several nanometers for the inter-surface separation.",
        "positive": "Three-body non-additive forces between spin-polarized alkali atoms: Three-body non-additive forces in systems of three spin-polarized alkali\natoms (Li, Na, K, Rb and Cs) are investigated using high-level ab initio\ncalculations. The non-additive forces are found to be large, especially near\nthe equilateral equilibrium geometries. For Li, they increase the three-atom\npotential well depth by a factor of 4 and reduce the equilibrium interatomic\ndistance by 0.9 A. The non-additive forces originate principally from chemical\nbonding arising from sp mixing effects."
    },
    {
        "anchor": "Cluster Formation and Percolation in Ethanol-Water mixtures: Results of systematic molecular dynamics studies of ethanol-water mixtures,\nover the entire concentration range, were reported previously to agree with\nexperimental X-ray diffraction data. These simulated systems are analyzed in\nthis work to examine cluster formation and percolation, using four different\nhydrogen bond definitions. Percolation analyses revealed that each mixture\n(even the one containing 80 mol % ethanol) is above the 3D percolation\nthreshold, with fractal dimensions, df, between 2.6 to 2.9, depending on\nconcentration. Monotype water cluster formation was also studied in the\nmixtures: 3D water percolation can be found in systems with less than 40 mol %\nethanol, with fractal dimensions between 2.53 and 2.84. These observations can\nbe put in parallel with experimental data on some thermodynamic quantities,\nsuch as the excess partial molar enthalpy and entropy.",
        "positive": "Inertial effects on rectification and diffusion of active Brownian\n  particles in an asymmetric channel: Micro- and nano-swimmers moving in a fluid solvent confined by structures\nthat produce entropic barriers are often described by overdamped active\nBrownian particle dynamics, where viscous effects are large and inertia plays\nno role. However, inertial effects should be considered for confined swimmers\nmoving in media where viscous effects are no longer dominant. Here, we study\nhow inertia affects the rectification and diffusion of self-propelled particles\nin a two-dimensional asymmetric channel. We show that most of the particles\naccumulate at the channel walls as the masses of the particles increase.\nFurthermore, the average particle velocity has a maximum as a function of the\nmass, indicating that particles with an optimal mass $M^{*}_{\\rm op}$ can be\nsorted from a mixture with particles of other masses. In particular, we find\nthat the effective diffusion coefficient exhibits an enhanced diffusion peak as\na function of the mass, which is a signature of the accumulation of most of the\nparticles at the channel walls. The dependence of $M^{*}_{\\rm op}$ on the\nrotational diffusion rate, self-propulsion force, aspect ratio of the channel,\nand active torque is also determined. The results of this study could stimulate\nthe development of strategies for controlling the diffusion of self-propelled\nparticles in entropic ratchet systems."
    },
    {
        "anchor": "Tuning the Topology of a Two-Dimensional Catenated DNA Network: Molecular topology of polymers plays a key role in determining their physical\nproperties. We studied herein the topological effects on the static and dynamic\nproperties of a 2D catenated network of DNA rings called a kinetoplast.\nRestriction enzymes, that cleave DNA at sequence-specific sites, are used to\nselectively cut and remove rings from the network and hence tune the molecular\ntopology while maintaining overall structural integrity. We find that topology\nhas minimal effects over the spatial extension of the 2D network, however, it\nsignificantly affects the relaxation behavior. The shape fluctuations of the\nnetwork are governed by two distinct characteristic time scales attributed to\nthe thermal fluctuations and confinement of the network. The relationship\nbetween the time constant of thermal relaxation and the amplitude of anisotropy\nfluctuations yields a universal scaling. Interestingly, this scaling is\nindependent of the detailed arrangements of rings and/or perforation within the\ncatenated networks. This study provides a route to tune the elastic properties\nof 2D catenated DNA networks by modifying the underlying topology in a rational\nand highly controllable manner.",
        "positive": "Energies for elastic plates and shells from quadratic-stretch elasticity: We derive stretching and bending energies for isotropic elastic plates and\nshells. Through the dimensional reduction of a bulk elastic energy quadratic in\nBiot strains, we obtain two-dimensional bending energies quadratic in bending\nmeasures featuring a bilinear coupling of stretches and geometric curvatures.\nFor plates, the bending measure is invariant under spatial dilations and\nnaturally extends primitive bending strains for straight rods. For shells or\nnaturally-curved rods, the measure is not dilation invariant, and contrasts\nwith previous \\emph{ad hoc} postulated forms. The corresponding field equations\nand boundary conditions feature moments linear in the bending measures, and a\ndecoupling of stretching and bending such that application of a pure moment\nresults in isometric deformation of a unique neutral surface, primitive\nbehaviors in agreement with classical linear response but not displayed by\ncommonly used analytical models. We briefly comment on relations between our\nenergies, those derived from a neo-Hookean bulk energy, and a commonly used\ndiscrete model for flat membranes. Although the derivation requires\nconsideration of stretch and rotation fields, the resulting energy and field\nequations can be expressed entirely in terms of metric and curvature components\nof deformed and reference surfaces."
    },
    {
        "anchor": "Bulk elastic fingering instability in Hele-Shaw cells: We demonstrate experimentally the existence of a purely elastic fingering\ninstability which arises when air penetrates into an elastomer confined in a\nHele-Shaw cell. Fingers appear sequentially and propagate within the bulk of\nthe material as soon as a critical strain, independent of the elastic modulus,\nis exceeded. Their width depends non-linearly on the distance between the\nconfining glass plates. A key element in the driving force of the instability\nis the adhesion of layers of gels to the plates, which results in a\nconsiderable expense of elastic energy during the growth of the air bubble.",
        "positive": "Elastic Moduli and Vibrational Modes in Jammed Particulate Packings: When we elastically impose a homogeneous, affine deformation on amorphous\nsolids, they also undergo an inhomogeneous, non-affine deformation, which can\nhave a crucial impact on the overall elastic response. To correctly understand\nthe elastic modulus $M$, it is therefore necessary to take into account not\nonly the affine modulus $M_A$, but also the non-affine modulus $M_N$ that\narises from the non-affine deformation. In the present work, we study the bulk\n($M=K$) and shear ($M=G$) moduli in static jammed particulate packings over a\nrange of packing fractions $\\varphi$. One novelty of this work is to elucidate\nthe contribution of each vibrational mode to the non-affine $M_N$ through a\nmodal decomposition of the displacement and force fields. In the vicinity of\nthe (un)jamming transition, $\\varphi_{c}$, the vibrational density of states,\n$g(\\omega)$, shows a plateau in the intermediate frequency regime above a\ncharacteristic frequency $\\omega^\\ast$. We illustrate that this unusual feature\napparent in $g(\\omega)$ is reflected in the behavior of $M_N$: As $\\varphi\n\\rightarrow \\varphi_c$, where $\\omega^\\ast \\rightarrow 0$, those modes for\n$\\omega < \\omega^\\ast$ contribute less and less, while contributions from those\nfor $\\omega > \\omega^\\ast$ approach a constant value which results in $M_N$ to\napproach a critical value $M_{Nc}$, as $M_N-M_{Nc} \\sim \\omega^\\ast$. At\n$\\varphi_c$ itself, the bulk modulus attains a finite value $K_c=K_{Ac}-K_{Nc}\n> 0$, such that $K_{Nc}$ has a value that remains below $K_{Ac}$. In contrast,\nfor the critical shear modulus $G_c$, $G_{Nc}$ and $G_{Ac}$ approach the same\nvalue so that the total value becomes exactly zero, $G_c = G_{Ac}-G_{Nc} =0$.\nWe explore what features of the configurational and vibrational properties\ncause such the distinction between $K$ and $G$, allowing us to validate\nanalytical expressions for their critical values."
    },
    {
        "anchor": "Thermodynamic size control in curvature-frustrated tubules:\n  Self-limitation with open boundaries: We use computational modeling to investigate the assembly thermodynamics of a\nparticle-based model for geometrically frustrated assembly, in which the local\npacking geometry of subunits is incompatible with uniform, strain-free\nlarge-scale assembly. The model considers discrete triangular subunits that\ndrive assembly towards a closed, hexagonal-ordered tubule, but have geometries\nthat locally favor negative Gaussian curvature. We use dynamical Monte Carlo\nsimulations and enhanced sampling methods to compute the free energy landscape\nand corresponding self-assembly behavior as a function of experimentally\naccessible parameters that control assembly driving forces and the magnitude of\nfrustration. The results determine the parameter range where finite-temperature\nself-limiting assembly occurs, in which the equilibrium assembly size\ndistribution is sharply peaked around a well-defined finite size. The\nsimulations also identify two mechanisms by which the system can escape\nfrustration and assemble to unlimited size, and determine the particle-scale\nproperties of subunits that suppress unbounded growth.",
        "positive": "Strong pressure-energy correlations in liquids as a configuration space\n  property: Simulations of temperature down jumps and crystallization: Computer simulations recently revealed that several liquids exhibit strong\ncorrelations between virial and potential energy equilibrium fluctuations in\nthe NVT ensemble [U. R. Pedersen {\\it et al.}, Phys. Rev. Lett. {\\bf 100},\n015701 (2008)]. In order to investigate whether these correlations are present\nalso far from equilibrium constant-volume aging following a temperature down\njump from equilibrium was simulated for two strongly correlating liquids, an\nasymmetric dumbbell model and Lewis-Wahnstr{\\\"o}m OTP, as well as for SPC water\nthat is not strongly correlating. For the two strongly correlating liquids\nvirial and potential energy follow each other closely during the aging towards\nequilibrium. For SPC water, on the other hand, virial and potential energy vary\nwith little correlation as the system ages towards equilibrium. Further proof\nthat strong pressure-energy correlations express a configuration space property\ncomes from monitoring pressure and energy during the crystallization (reported\nhere for the first time) of supercooled Lewis-Wahnstr{\\\"o}m OTP at constant\ntemperature."
    },
    {
        "anchor": "Effects of surface functional groups on the formation of\n  nanoparticle-protein corona: Herein, we examined the dependence of protein adsorption on the nanoparticle\nsurface in the presence of functional groups. Our UV-visible spectrophotometry,\ntransmission electron microscopy, infrared spectroscopy and dynamic light\nscattering measurements evidently suggested that the functional groups play an\nimportant role in the formation of nanoparticle-protein corona. We found that\nuncoated and surfactant-free silver nanoparticles derived from a laser ablation\nprocess promoted a maximum protein (bovine serum albumin) coating due to\nincreased changes in entropy. On the other hand, BSA displayed a lower affinity\nfor electrostatically stabilized nanoparticles due to the constrained entropy\nchanges.",
        "positive": "Uncovering the dynamic precursors to motor-driven contraction of active\n  gels: Cells and tissues have the remarkable ability to actively generate the forces\nrequired to change their shape. This active mechanical behavior is largely\nmediated by the actin cytoskeleton, a crosslinked network of actin filaments\nthat is contracted by myosin motors. Experiments and active gel theories have\nestablished that the length scale over which gel contraction occurs is governed\nby a balance between molecular motor activity and crosslink density. By\ncontrast, the dynamics that govern the contractile activity of the cytoskeleton\nremain poorly understood. Here we investigate the microscopic dynamics of\nreconstituted actin-myosin networks using simultaneous real-space video\nmicroscopy and Fourier-space dynamic light scattering. Light scattering reveals\nrich and unanticipated microscopic dynamics that evolve with sample age. We\nuncover two dynamical precursors that precede macroscopic gel contraction. One\nis characterized by a progressive acceleration of stress-induced\nrearrangements, while the other consists of sudden rearrangements that depend\non network adhesion to the boundaries and are highly heterogeneous. Our\nfindings reveal an intriguing analogy between self-driven rupture and collapse\nof active gels to the delayed rupture of passive gels under external loads."
    },
    {
        "anchor": "Quantum fluctuations in one-dimensional arrays of condensates: The effects of quantum and thermal fluctuations upon the fringe structure\npredicted to be observable in the momentum distribution of coupled\nBose-Einstein condensates are studied by the effective-potential method. For a\ndouble-well trap, the coherence factor recently introduced by Pitaevskii and\nStringari [Phys. Rev. Lett. 87, 180402 (2001)] is calculated using the\neffective potential approach and is found in good agreement with their result.\nThe calculations are extended to the case of a one-dimensional array of\ncondensates, showing that quantum effects are essentially described through a\nsimple renormalization of the energy scale in the classical analytical\nexpression for the fringe structure. The consequences for the experimental\nobservability are discussed.",
        "positive": "Local NMR Relaxation of Dendrimers in the Presence of Hydrodynamic\n  Interactions: We study the role of hydrodynamic interactions for the relaxation of\nsegments' orientations in dendrimers. The dynamics is considered in the Zimm\nframework. It is shown that inclusion of correlations between segments'\norientations plays a major role for the segments' mobility, that reveals itself\nin the NMR relaxation functions. The enhancement of the reorientation dynamics\nof segments due to the hydrodynamic interactions is more significant for the\ninner segments. This effect is clearly pronounced in the reduced spectral\ndensity $\\omega J(\\omega)$, whose maximum shifts to higher frequencies when the\nhydrodynamic interactions are taken into account."
    },
    {
        "anchor": "Efficacy of face coverings in reducing transmission of COVID-19:\n  calculations based on models of droplet capture: In the COVID--19 pandemic, among the more controversial issues is the use of\nmasks and face coverings. Much of the concern boils down to the question --\njust how effective are face coverings? One means to address this question is to\nreview our understanding of the physical mechanisms by which masks and\ncoverings operate -- steric interception, inertial impaction, diffusion and\nelectrostatic capture. We enquire as to what extent these can be used to\npredict the efficacy of coverings. We combine the predictions of the models of\nthese mechanisms which exist in the filtration literature and compare the\npredictions with recent experiments and lattice Boltzmann simulations, and find\nreasonable agreement with the former and good agreement with the latter.\nBuilding on these results, we explore the parameter space for woven cotton\nfabrics to show that three-layered cloth masks can be constructed with\ncomparable filtration performance to surgical masks under ideal conditions.\nReusable cloth masks thus present an environmentally friendly alternative to\nsurgical masks so long as the face seal is adequate enough to minimise leakage.",
        "positive": "Networks of helix-forming polymers: Biological molecules can form hydrogen bonds between nearby residues, leading\nto helical secondary structures. The associated reduction of configurational\nentropy leads to a temperature dependence of this effect: the \"helix-coil\ntransition\". Since the formation of helices implies a dramatic shortening of\nthe polymer dimensions, an externally imposed end-to-end distance R affects the\nequilibrium helical fraction of the polymer and the resulting force- extension\ncurves show anomalous plateau regimes. In this article, we investigate the\nbehaviour of a cross-linked network of such helicogenic molecules,\nparticularly, focusing on the coupling of the (average) helical content present\nin a network to the externally imposed strain. We show that both an elongation\nand compression can lead to an increase in helical domains under appropriate\nconditions."
    },
    {
        "anchor": "Critical splay fluctuations and colossal flexoelectric effect above\n  non-polar to polar nematic phase transition: The recent discovery of nematic liquid crystals with polar order\n(ferroelectric nematic) has created immense interest. Despite intensive\nresearch, several physical properties of this liquid crystal are yet to be\ninvestigated and understood. Here, we report experimental studies on the\nbirefringence and exoelectric coefficient of a polar nematic (NF) liquid\ncrystal. Our experiments directly reveal that the splay fluctuations influence\nthe birefringence several degrees above the nonpolar (N) to polar-nematic (NF)\nphase transition temperature and the heat capacity exponent obtained from the\ntilt angle fluctuations is close to the value reported in adiabatic scanning\ncalorimetry measurements. The flexoelectric coefficient of the nonpolar nematic\nphase shows a power-law dependence on temperature. Our results demonstrate a\nstrong coupling of splay fluctuations with electric polarization that reduces\nthe splay elastic constant and consequently enhances the flexoelectric\ncoefficient. These results are important for forthcoming applications as well\nas for understanding all pretransitional effects in ferroelectric nematic\nliquid crystals.",
        "positive": "Annihilation dynamics of stringlike topological defects in a nematic\n  lyotropic liquid crystal: Topological defects can appear whenever there is some type of ordering. Its\nubiquity in nature has been the subject of several studies, from early Universe\nto condensed matter. In this work, we investigated the annihilation dynamics of\ndefects and antidefects in a lyotropic nematic liquid crystal (ternary mixture\nof potassium laurate, decanol and deionized-destilated water) using the\npolarized optical light microscopy technique. We analyzed Schlieren textures\nwith topological defects produced due to a symmetry breaking in the transition\nof the isotropic to nematic calamitic phase after a temperature quench. As\nresult, we obtained for the distance D between two annihilating defects\n(defect-antidefect pair), as a function of time t remaining for the\nannihilation, the scaling law D ~ t^{\\alpha}, with \\alpha = 0.390 and standard\ndeviation \\sigma = 0.085. Our findings go in the direction to extend\nexperimental results related to dynamics of defects in liquid crystals since\nonly thermotropic and polymerics ones had been investigated. In addition, our\nresults are in good quantitative agreement with previous investigations on the\nsubject."
    },
    {
        "anchor": "Dynamics of swelling and drying in a spherical gel: Swelling is a volumetric-growth process in which a porous material expands by\nspontaneous imbibition of additional pore fluid. Swelling is distinct from\nother growth processes in that it is inherently poromechanical: Local expansion\nof the pore structure requires that additional fluid be drawn from elsewhere in\nthe material, or into the material from across the boundaries. Here, we study\nthe swelling and subsequent drying of a sphere of hydrogel. We develop a\ndynamic model based on large-deformation poromechanics and the theory of ideal\nelastomeric gels, and we compare the predictions of this model with a series of\nexperiments performed with polyacrylamide spheres. We use the model and the\nexperiments to study the complex internal dynamics of swelling and drying, and\nto highlight the fundamentally transient nature of these strikingly different\nprocesses. Although we assume spherical symmetry, the model also provides\ninsight into the transient patterns that form and then vanish during swelling\nas well as the risk of fracture during drying.",
        "positive": "Towards Better Integrators for Dissipative Particle Dynamics Simulations: Coarse-grained models that preserve hydrodynamics provide a natural approach\nto study collective properties of soft-matter systems. Here, we demonstrate\nthat commonly used integration schemes in dissipative particle dynamics give\nrise to pronounced artifacts in physical quantities such as the compressibility\nand the diffusion coefficient. We assess the quality of these integration\nschemes, including variants based on a recently suggested self-consistent\napproach, and examine their relative performance. Implications of\nintegrator-induced effects are discussed."
    },
    {
        "anchor": "Raman scattering as a probe of intermediate phases in glassy networks: Bulk glass formation occurs over a very small part of phase space, and \"good\"\nglasses (which form even at low quench rates ~ 10K/sec) select an even smaller\npart of that accessible phase space. An axiomatic theory provides the physical\nbasis of glass formation, and identifies these sweet spots of glass formation\nwith existence of rigid but stress-free networks for which experimental\nevidence is rapidly emerging. Recently, theory and experiment have come\ntogether to show that these sweet spots of glass formation occur over a range\nof chemical compositions identified as Intermediate Phases. These ranges appear\nto be controlled by elements of local and medium range molecular structures\nthat form isostatically rigid networks. Intermediate Phase glasses possess\nnon-hysteretic glass transitions (Tgs) that do not age much. Raman scattering\nhas played a pivotal role in elucidating molecular structure of glasses in\ngeneral, and in identifying domains of Intermediate Phases. Experiments reveal\nthese phases to possess sharp phase boundaries and to be characterized by an\noptical elasticity that varies with network mean coordination number, r, as\npower-law. In this review, we provide examples in chalcogenide and oxide glass\nsystems where these phases along with optical elasticity power-laws have been\nestablished. Intermediate Phase glasses represent self-organized nanostructured\nfunctional materials optimized by nature.",
        "positive": "Direct observation of homogeneous cavitation in nanopores: We report on the evaporation of hexane from porous alumina and silicon\nmembranes. These membranes contain billions of independent nanopores tailored\nto an ink-bottle shape, where a cavity several tens of nanometers in diameter\nis separated from the bulk vapor by a constriction. For alumina membranes with\nnarrow enough constrictions, we demonstrate that cavity evaporation proceeds by\ncavitation. Measurements of the pressure dependence of the cavitation rate\nfollow the predictions of the bulk, homogeneous, classical nucleation theory,\ndefinitively establishing the relevance of homogeneous cavitation as an\nevaporation mechanism in mesoporous materials. Our results imply that porous\nalumina membranes are a promising new system to study liquids in a deeply\nmetastable state."
    },
    {
        "anchor": "Viscoelasticity of a colloidal gel during dynamical arrest: evolution\n  through the critical gel and comparison with a soft colloidal glass: We consider gelation of colloidal particles in suspension after cessation of\nshear flow. Particle aggregation is driven by a temperature-tunable attractive\npotential which controls the growth of clusters under isothermal conditions. A\nseries of frequency resolved time sweeps is used to systematically reconstruct\nthe frequency dependent dynamic moduli as a function of time and temperature or\nattraction strength. The data display typical hallmarks of gelation with an\nabrupt transition from a fluid state into a dynamically arrested gel state\nafter a characteristic gelation time $t_g$ that varies exponentially with\ntemperature and serves to collapse the evolution of the system onto a universal\ncurve. We observe the viscoelastic properties of the critical gel where we find\nthat $G'(\\omega)\\approxeq G''(\\omega)\\sim \\omega^{n_c}$ where $n_c=0.5$ in a\nnarrow time window across all attraction strengths. We measure a dynamic\ncritical exponent of $\\kappa=0.25$ which is similar to that observed in\ncrosslinked polymer gels. The approach to the critical gel is therefore\ngoverned by $\\eta_0\\sim-\\epsilon^{-s}$ and $G_e\\sim\\epsilon^z$ with $s=z=2$\nwhere $\\epsilon=p/p_c-1$ is the distance to the gel point. Remarkably, the\nrelaxation moduli of the near-critical gels are identical across the\ntemperatures considered, with $G(t)\\approx0.33t^{-0.5}$. This suggests an\nunderlying strong similarity in gel structure in the regime of attraction\nstrengths considered, despite the differences in aggregation kinetics. We\ncontrast these findings with the behavior of a colloidal glass undergoing\ndynamical arrest where no critical state is observed and where the arrest time\nof the system displays a marked frequency dependence. These findings highlight\nthe underlying structural differences between colloidal gels and glasses which\nare manifest in their dynamic properties in the vicinity of the liquid-to-solid\ntransition.",
        "positive": "Modern Definition of Bioactive Glasses and Glass-Ceramics: Bioactive glasses (BGs) and glass-ceramics (BGCs) have become a diverse\nfamily of materials being applied for treatment of many medical conditions. The\ntraditional understanding of bioactive glasses and glass-ceramics pins them to\nbone-bonding capability without considering the other fields where they excel,\nsuch as soft tissue repair. We attempt to provide an updated definition of BGs\nand BGCs by comparing their structure, processing, and properties to those of\nother biomaterials. The proposed modern definition allows for consideration of\nall applications where the BGs and BGCs are currently used in the clinic and\nwhere the future of these promising biomaterials will grow. The new proposed\ndefinition of a bioactive glass is \"a non-equilibrium, non-crystalline material\nthat has been designed to induce specific biological activity\". The proposed\ndefinition of a bioactive glass-ceramic is \"an inorganic, non-metallic material\nthat contains at least one crystalline phase within a glassy matrix and has\nbeen designed to induce specific biological activity.\" BGs and BGCs can bond to\nbone and soft tissues or contribute to their regeneration. They can deliver a\nspecified concentration of inorganic therapeutic ions, heat for\nmagnetic-induced hyperthermia or laser-induced phototherapy, radiation for\nbrachytherapy, and drug delivery to combat pathogens and cancers."
    },
    {
        "anchor": "Unilateral interactions in granular packings: A model for the anisotropy\n  modulus: Unilateral interparticle interactions have an effect on the elastic response\nof granular materials due to the opening and closing of contacts during\nquasi-static shear deformations. A simplified model is presented, for which\nconstitutive relations can be derived. For biaxial deformations the elastic\nbehavior in this model involves three independent elastic moduli: bulk, shear,\nand anisotropy modulus. The bulk and the shear modulus, when scaled by the\ncontact density, are independent of the deformation. However, the magnitude of\nthe anisotropy modulus is proportional to the ratio between shear and\nvolumetric strain. Sufficiently far from the jamming transition, when\ncorrections due to non-affine motion become weak, the theoretical predictions\nare qualitatively in agreement with simulation results.",
        "positive": "Thermoosmosis of a near-critical binary fluid mixture: a general\n  formulation and universal flow direction: We consider a binary fluid mixture, which lies in the one-phase region near\nthe demixing critical point, and study its transport through a capillary tube\nlinking two large reservoirs. We assume that short-range interactions cause\npreferential adsorption of one component on the tube's wall. The adsorption\nlayer can become much thicker than the molecular size, which enables us to\napply hydrodynamics based on a coarse-grained free-energy functional. For\nlinear transport phenomena induced by gradients of the pressure, composition,\nand temperature along a cylindrical tube, we obtain the formulas of the Onsager\ncoefficients to extend our previous results on isothermal transport, assuming\nthe critical composition in the middle of each reservoir in the reference\nequilibrium state. Among the linear transport phenomena, we focus on\nthermoosmosis -- mass flow due to a temperature gradient. We explicitly derive\na formula for the thermal force density, which is nonvanishing in the\nadsorption layer and causes thermoosmosis. This formula for a near-critical\nbinary fluid mixture is an extension of the conventional formula for a\none-component fluid, expressed in terms of local excess enthalpy. We predict\nthat the direction of thermoosmotic flow of a mixture near the upper (lower)\nconsolute point is the same as (opposite to) that of the temperature gradient,\nirrespective of which component is adsorbed on the wall. Our procedure would\nalso be applied to dynamics of a soft material, whose mesoscopic inhomogeneity\ncan be described by a coarse-grained free-energy functional."
    },
    {
        "anchor": "Critical Casimir Forces and Colloidal Phase Transitions in a\n  Near-Critical Solvent : A Simple Model Reveals a Rich Phase Diagram: From experimental studies it is well-known that colloidal particles suspended\nin a near-critical binary solvent exhibit interesting aggregation phenomena,\noften associated with colloidal phase transitions, and assumed to be driven by\nlong-ranged solvent mediated (SM) interactions (critical Casimir forces), set\nby the (diverging) correlation length of the solvent. We present the first\nsimulation and theoretical study of an explicit model of a ternary mixture that\nmimics this situation. Both the effective SM pair interactions and the full\nternary phase diagram are determined for Brownian discs suspended in an\nexplicit two-dimensional supercritical binary liquid mixture. Gas-liquid and\nfluid-solid transitions are observed in a region that extends well-away from\ncriticality of the solvent reservoir. We discuss to what extent an effective\npair-potential description can account for the phase behavior we observe. Our\nstudy provides a fresh perspective on how critical fluctuations of the solvent\nmight influence colloidal self-assembly.",
        "positive": "Understanding coil-to-globule transition of polymers with the aid of a\n  novel cluster analysis technique: In this article, a novel cluster analysis algorithm was employed in the study\nof polymer coil to globule transition via single chain Monte Carlo simulations.\nThe algorithm, which has been recently applied in Molecular Dynamics\nsimulations of atomistic systems that tend to phase separate [arXiv: 1307.7366\n[cond-mat.soft]], provides us with a convenient means to map out the dynamics\nof \"pearls\" formation along the backbone chain together with extracting\nmeaningful quantitative information about their shape and size distribution.\nPreliminary findings tend to favour a two-stage model of collapse kinetics,\nalthough a more complicated picture emerges when looking at the details of\ncluster formation along the chain."
    },
    {
        "anchor": "Ion steric effect induces giant enhancement of thermoelectric conversion\n  in electrolyte-filled nanochannels: Ionic thermoelectricity in nanochannels has received increasing attention\nbecause of its advantages such as high Seebeck coefficient and low cost.\nHowever, most studies have focused on dilute simple electrolytes that neglect\nthe effects of finite ion sizes and short-range electrostatic correlation.\nHere, we reveal a new thermoelectric mechanism arising from the coupling of ion\nsteric effect due to finite ion sizes and ion thermodiffusion in electric\ndouble layers, using both theoretical and numerical methods. We show that this\nmechanism can significantly enhance the thermoelectric response in nanoconfined\nelectrolytes, depending on the properties of electrolytes and nanochannels.\nCompared to the previously known mechanisms, the new mechanism can increase the\nSeebeck coefficient by 100\\% or even one order of magnitude enhancement under\noptimal conditions. Moreover, we demonstrate that the short-range electrostatic\ncorrelation can help preserve the Seebeck coefficient enhancement in weaker\nconfinement or in more concentrated electrolytes.",
        "positive": "Randomly stacked open-cylindrical shells as a functional mechanical\n  device: Structures with artificial mechanical properties, often called mechanical\nmetamaterials, exhibit divergent yet tunable performance. Various types of\nmechanical metamaterials have been proposed, which harness light or magnetic\ninteractions, structural instabilities in slender or hollow structures, and\ncontact friction. However, most of the designs are precisely engineered without\nany imperfections, in order to perform as programmed. Here, we study the\nmechanical performance of randomly stacked cylindrical-shells, which act as a\ndisordered mechanical metamaterial. Combining experiments and simulations, we\ndemonstrate that the stacked shells can absorb and store mechanical energy upon\ncompression by exploiting large deformation and relocation of shells,\nsnap-fits, and friction. Although shells are oriented randomly, the system\nexhibits robust mechanical performance controlled by friction and geometry. Our\nresults demonstrate that the rearrangement of flexible components could yield\nversatile but predictive mechanical responses."
    },
    {
        "anchor": "Stacking Interactions in Denaturation of DNA Fragments: A mesoscopic model for heterogeneous DNA denaturation is developed in the\nframework of the path integral formalism. The base pair stretchings are treated\nas one-dimensional, time dependent paths contributing to the partition\nfunction. The size of the paths ensemble, which measures the degree of\ncooperativity of the system, is computed versus temperature consistently with\nthe model potential physical requirements. It is shown that the ensemble size\nstrongly varies with the molecule backbone stiffness providing a quantitative\nrelation between stacking and features of the melting transition. The latter is\nan overall smooth crossover which begins from the \\emph{adenine-thymine} rich\nportions of the fragment. The harmonic stacking coupling shifts, along the\n$T$-axis, the occurrence of the multistep denaturation but it does not change\nthe character of the crossover. The methods to compute the fractions of open\nbase pairs versus temperature are discussed: by averaging the base pair\ndisplacements over the path ensemble we find that such fractions signal the\nmultisteps of the transition in good agreement with the indications provided by\nthe specific heat plots.",
        "positive": "Dynamic Phases, Clustering, and Lane Formation for Driven Disk Systems\n  in the Presence of Quenched Disorder: We numerically examine the dynamic phases and pattern formation of\ntwo-dimensional monodisperse repulsive disks driven over random quenched\ndisorder. We show that there is a series of distinct dynamic regimes as a\nfunction of increasing drive, including a clogged or pile-up phase near\ndepinning, a homogeneous disordered flow state, and a dynamically phase\nseparated regime consisting of high density crystalline regions surrounded by a\nlow density of disordered disks. At the highest drives the disks arrange into\none-dimensional moving lanes. The phase separated regime has parallels with\nphase separation observed in active matter systems, and arises in the disk\nsystem due to the combination of nonequilibrium fluctuations and density\ndependent mobility. We discuss how this system exhibits pronounced differences\nfrom previous studies of driven particles moving over random substrates where\nthe particles, such as superconducting vortices or electron crystals, have\nlonger range repulsive interactions, and where dynamical phase separation and\nstrong one-dimensional moving chain effects are not observed. The system we\nconsider could be realized experimentally using sterically interacting colloids\ndriven over random pinning arrays or quasi-two-dimensional granular matter\nflowing over rough landscapes."
    },
    {
        "anchor": "Electric double layer for spherical particles in salt-free concentrated\n  suspensions including ion size effects: The equilibrium electric double layer (EDL) that surrounds the colloidal\nparticles is determinant for the response of a suspension under a variety of\nstatic or alternating external fields. An ideal salt-free suspension is\ncomposed by the charged colloidal particles and the ionic countercharge\nreleased by the charging mechanism. The existing macroscopic theoretical models\ncan be improved by incorporating different ionic effects usually neglected in\nprevious mean-field approaches, which are based on the Poisson-Boltzmann\nequation (PB). The influence of the finite size of the ions seems to be quite\npromising because it has been shown to predict phenomena like charge reversal,\nwhich has been out of the scope of classical PB approximations. In this work we\nnumerically obtain the surface electric potential and the counterions\nconcentration profiles around a charged particle in a concentrated salt-free\nsuspension corrected by the finite size of the counterions. The results show\nthe large importance of such corrections for moderate to high particle charges\nat every particle volume fraction, specially, when a region of closest approach\nof the counterions to the particle surface is considered. We conclude that\nfinite ion size considerations are obeyed for the development of new\ntheoretical models to study nonequilibrium properties in concentrated colloidal\nsuspensions, particularly the salt-free ones with small and highly charged\nparticles.",
        "positive": "Conformational properties of polymers in anisotropic environments: We analyze the conformational properties of polymer macromolecules in\nsolutions in presence of extended structural obstacles of (fractal) dimension\n$\\varepsilon_d$ causing the anisotropy of environment. Applying the\npruned-enriched Rosenbluth method (PERM), we obtain numerical estimates for\nscaling exponents and universal shape parameters of polymers in such\nenvironments for a wide range $0<\\varepsilon_d<2$ in space dimension $d=3$. An\nanalytical description of the model is developed within the des Cloizeaux\ndirect polymer renormalization scheme. Both numerical and analytical studies\nqualitatively confirm the existence of two characteristic length scales of\npolymer chain in directions parallel and perpendicular to the extended defects."
    },
    {
        "anchor": "Entropic stress of grafted polymer chains in shear flow: We analyze the shear response of grafted polymer chains in shear flow via\ncoarse-grained molecular dynamics simulations. Our simulations confirm that the\nshear response is dominated by the brush's outermost correlation volume, which\ndepends on shear rate at high Weissenberg number. The system's shear stress can\nbe approximated by the brush's entropic stress. The simulations further reveal\nthat at low Weissenberg number, the entropic shear stress of grafted chains is\nindependent of the Weissenberg number. Increasing the Weissenberg number leads\nto Wi-dependent behavior: chains first reorient along the shear direction and\nelongate at higher Wi. The entropic shear stress increases linearly with\nWeissenberg number in this regime. We relate these calculations to experimental\nobservations on the velocity dependence of brush and hydrogel friction.",
        "positive": "Rodlike counterions at heterogeneously charged surfaces: We study the spatial and orientational distribution of rodlike counterions\n(such as mobile nanorods) as well as the effective interaction mediated by them\nbetween two plane-parallel surfaces that carry fixed (quenched) heterogeneous\ncharge distributions. The rodlike counterions are assumed to have an internal\ncharge distribution, specified by a multivalent monopolar moment and a finite\nquadrupolar moment, and the quenched surface charge is assumed to be randomly\ndistributed with equal mean and variance on the two surfaces. While equally\ncharged surfaces are known to repel within the traditional mean-field theories,\nthe presence of multivalent counterions has been shown to cause attractive\ninteractions between uniformly charged surfaces due to the prevalence of strong\nelectrostatic couplings that grow rapidly with the counterion valency. We show\nthat the combined effects due to electrostatic correlations (caused by the\ncoupling between the mean surface field and the multivalent, monopolar, charge\nvalency of counterions) as well as the disorder-induced interactions (caused by\nthe coupling between the surface disorder field and the quadrupolar moment of\ncounterions) lead to much stronger attractive interactions between two randomly\ncharged surfaces. The interaction profile turns out to be a nonmonotonic\nfunction of the intersurface separation, displaying an attractive minimum at\nrelatively small separations, where the ensuing attraction can exceed the\nmaximum strong-coupling attraction (produced by multivalent monopolar\ncounterions between uniformly charged surfaces) by more than an order of\nmagnitude."
    },
    {
        "anchor": "Screening in Yukawa fluid mixtures: The effective pair potential between mesoscopic charged particles in a\nneutralising background medium takes a Yukawa form $\\exp(-\\lambda r)/r$ with\nscreening length $\\lambda^{-1}$. We consider a dilute suspension of such Yukawa\nparticles dispersed in a solvent with correlation length $\\xi<\\lambda^{-1}$ and\nshow that the Yukawa interaction is `screened' if the pair potentials between\nsolvent particles exhibit Yukawa decay with the same screening length\n$\\lambda^{-1}$. However, if the solvent pair potentials are shorter ranged than\nthe solute Yukawa potentials, then the effective potential between pairs of\nsolute particles is `unscreened', i.e. the effective potential between the\nsolute particles is equal to the bare potential at large particle separations.",
        "positive": "Elasto-capillary circumferential buckling of soft tubes under axial\n  loading: existence and competition with localised beading and periodic axial\n  modes: We provide an extension to previous analysis of the localised beading\ninstability of soft slender tubes under surface tension and axial stretching.\nThe primary questions pondered here are: under what loading conditions, if any,\ncan bifurcation into circumferential buckling modes occur, and do such\nsolutions dominate localisation and periodic axial modes? Three distinct\nboundary conditions are considered; in case 1 the tube's curved surfaces are\ntraction free and under surface tension, whilst in cases 2 and 3 the inner and\nouter surfaces (respectively) are fixed to prevent radial displacement and\nsurface tension. A linear bifurcation analysis is conducted to determine\nnumerically the existence of circumferential mode solutions. In case 1 we focus\non the tensile stress regime given the preference of slender compressed tubes\ntowards Euler buckling over axial wrinkling. We show that tubes under several\nloading paths are highly sensitive to circumferential modes; in contrast,\nlocalised and periodic axial modes are absent, suggesting that the\ncircumferential buckling is dominant by default. In case 2, circumferential\nmode solutions are associated with negative surface tension values and thus are\nphysically implausible. Circumferential buckling solutions are shown to exist\nin case 3 for tensile and compressive axial loads, and we demonstrate for\nmultiple loading scenarios their dominance over localisation and periodic axial\nmodes within specific parameter regimes."
    },
    {
        "anchor": "Defect Loops in Three-Dimensional Active Nematics as Active Multipoles: We develop a description of defect loops in three-dimensional active nematics\nbased on a multipole expansion of the far-field director and show how this\nleads to a self-dynamics dependent on the loop's geometric type. The dipole\nterm leads to active stresses that generate a global self-propulsion for splay\nand bend loops. The quadrupole moment is non-zero only for non-planar loops and\ngenerates a net `active torque', such that defect loops are both self-motile\nand self-orienting. Our analysis identifies right- and left-handed twist loops\nas the only force and torque free geometries, suggesting a mechanism for\ngenerating an excess of twist loops. Finally, we determine the Stokesian flows\ncreated by defect loops and describe qualitatively their hydrodynamics.",
        "positive": "Anharmonic transitions in nearly dry L-cysteine I: Two special dynamical transitions of universal character have been recently\nobserved in macromolecules at $T_{D}\\sim 180 - 220$ K and $T^{*}\\sim 100$ K.\nDespite their relevance, a complete understanding of the nature of these\ntransitions and their consequences for the bio-activity of the macromolecule is\nstill lacking. Our results and analysis concerning the temperature dependence\nof structural, vibrational and thermodynamical properties of the orthorhombic\npolymorph of the amino acid L-cysteine (at a hydration level of 3.5%) indicated\nthat the two referred temperatures define the triggering of very simple and\nspecific events that govern all the biochemical interactions of the\nbiomolecule: activation of rigid rotors ($T<T^{*}$), phonon-phonon interactions\nwith phonons of water dimer ($T^{*}<T<T_{D}$), and water rotational barriers\nsurpassing ($T>T_{D}$)."
    },
    {
        "anchor": "Microhydrodynamics of an autophoretic particle near a plane interface: We study the autophoretic motion of a spherical active particle interacting\nchemically and hydrodynamically with its fluctuating environment in the limit\nof rapid diffusion and slow viscous flow. Then, the chemical and hydrodynamic\nfields can be expressed in terms of integrals over boundaries. The resulting\nboundary-domain integral equations provide a direct way of obtaining the\ntraction on the particle, requiring the solution of linear integral equations.\nAn exact solution for the chemical and hydrodynamic problems is obtained for a\nparticle in an unbounded domain. For motion near boundaries, we provide\ncorrections to the unbounded solutions in terms of chemical and hydrodynamic\nGreen's functions, preserving the dissipative nature of autophoresis in a\nviscous fluid for all physical configurations. Using this, we give the fully\nstochastic update equations for the Brownian trajectory of an autophoretic\nparticle in a complex environment. Finally, we demonstrate our method by\nstudying autophoresis near a plane interface of fixed viscosity ratio and\nsolute permeability. We provide explicit solutions to the chemical and\nhydrodynamic problems with high accuracy for this system geometry. We apply our\ntheoretical results in numerical simulations of the dynamics of a bottom-heavy\nBrownian Janus particle near a wall.",
        "positive": "Universal thermal response of the multiscale nanodomains formed in\n  trans-anethol/ethanol/water surfactant-free microemulsion: Hypothesis: Surfactant-free microemulsion (SFME), an emerging phenomenology\nthat occurs in the monophasic zone of a broad category of ternary mixtures\n'hydrophobe/hydrotrope/water', has attracted extensive interests due to their\nunique physicochemical properties. The potential of this kind of ternary fluid\nfor solubilization and drug delivery make them promising candidates in many\nindustrial scenarios. Experiments: Here the thermodynamic behavior of these\nmultiscale nanodomains formed in the ternary trans-anethol/ethanol/water system\nover a wide range of temperatures is explored. The macroscopic physical\nproperties of the ternary solutions are characterized, with revealing the\ntemperature dependence of refractive index and dynamic viscosity. Findings:\nWith increasing temperature, the ternary system shows extended areas in the\nmonophasic zone. We demonstrate that the phase behavior and the multiscale\nnanodomains formed in the monophasic zone can be precisely and reversibly tuned\nby altering the temperature. Increasing temperature can destroy the stability\nof the multiscale nanodomains in equilibrium, with an exponential decay in the\nscattering light intensity. Nevertheless, molecular-scale aggregates and\nmesoscopic droplets exhibit significantly different response behaviors to\ntemperature stimuli. The temperature-sensitive nature of the ternary SFME\nsystem provides a crucial step forward exploring and industrializing its\nstability."
    },
    {
        "anchor": "Remarks on Flory theory of a self-avoiding chain under cylindrical\n  confinement: Despite its limitations, mainly due to its simplicity, Flory theory has been\nextended to many other important cases, e.g., linear chains with stiffness and\npolymers of various topology in a confined space. Surprisingly, the severe\nlimitations of the applicability of the Flory-type free energy for cylindrical\nconfinement have not been well noticed. In this note, we present a simple\n\"renormalized\" form of Flory energy for 1D system, from which one can obtain\nthe following three quantities consistently: the equilibrium end-to-end\ndistance of the chain, the confinement free energy, and the effective \"Hookian\"\nspring constant of the chain. Our result has practical implications for many\nexperimental studies concerning DNA molecules in nano-/micro-channels.",
        "positive": "Fast DNA Sequencing via Transverse Electronic Transport: A rapid and low-cost method to sequence DNA would usher in a revolution in\nmedicine. We propose and theoretically show the feasibility of a protocol for\nsequencing based on the distributions of transverse electrical currents of\nsingle-stranded DNA while it translocates through a nanopore. Our estimates,\nbased on the statistics of these distributions, reveal that sequencing of an\nentire human genome could be done with very high accuracy in a matter of hours\nwithout parallelization, e.g., orders of magnitude faster than present\ntechniques. The practical implementation of our approach would represent a\nsubstantial advancement in our ability to study, predict and cure diseases from\nthe perspective of the genetic makeup of each individual."
    },
    {
        "anchor": "Pair Interaction of Catalytically Active Colloids: From Assembly to\n  Escape: The dynamics and pair trajectory of two self-propelled colloids are reported.\nThe autonomous motions of the colloids are due to a catalytic chemical reaction\ntaking place asymmetrically on their surfaces that generates a concentration\ngradient of interactive solutes around the particles and actuate particle\npropulsion. We consider two spherical particles with symmetric catalytic caps\nextending over the local polar angles $\\theta^1_{cap}$ and $\\theta^2_{cap}$\nfrom the centers of active sectors in an otherwise quiescent fluid. A combined\nanalytical-numerical technique was developed to solve the coupled mass transfer\nequation and the hydrodynamics in the Stokes flow regime. The ensuing pair\ntrajectory of the colloids is controlled by the reacting coverages\n$\\theta^j_{cap}$ and their initial relative orientation with respect to each\nother. Our analysis indicates two possible scenarios for pair trajectories of\ncatalytic self-propelled particles: either the particles approach, come into\ncontact and assemble or they interact and move away from each other (escape).\nFor arbitrary motions of the colloids, it is found that the direction of\nparticle rotations is the key factor in determining the escape or assembly\nscenario. Based on the analysis, a phase diagram is sketched for the pair\ntrajectory of the catalytically active particles as a function of active\ncoverages and their initial relative orientations. We believe this study has\nimportant implications in elucidation of collective behaviors of\nauotophoretically self-propelled colloids.",
        "positive": "pH-Dependent Selective Protein Adsorption into Mesoporous Silica: The adsorption of lysozyme, cytochrome c and myoglobin, similar-sized\nglobular proteins of approximately 1.5 nm radius, into the mesoporous silica\nmaterial Santa Barbara Amorphous-15 (SBA-15) with 3.3 nm mean pore radius has\nbeen studied photometrically for aqueous solutions containing a single protein\ntype and for binary protein mixtures. Distinct variations in the absolute and\nrelative adsorption behavior are observed as a function of the solution's\npH-value, and thus pore wall and protein charge. The proteins exhibit the\nstrongest binding below their isoelectric points pI, which indicates the\ndominance of electrostatic interactions between charged amino acid residues and\nthe -OH groups of the silica surface in the mesopore adsorption process.\nMoreover, we find for competitive adsorption in the restricted, tubular pore\ngeometry that the protein type which shows the favoured binding to the pore\nwall can entirely suppress the adsorption of the species with lower binding\naffinity, even though the latter would adsorb quite well from a single\ncomponent mixture devoid of the strongly binding protein. We suggest that this\ndifferent physicochemical behavior along with the large specific surface and\nthus adsorption capability of mesoporous glasses can be exploited for\nseparation of binary mixtures of proteins with distinct pI by adjusting the\naqueous solution's pH."
    },
    {
        "anchor": "Continuity and discontinuity of kirigami's high-extensibility\n  transition: a statistical-physics viewpoint: Recently, kirigami's high extensibility has been understood as a transition\nin the force-elongation curve. In this paper, we consider a model, which\nmodifies our previous model, to show a striking analogy between the present\ntheory and Landau theory of continuous thermodynamic transitions, if we regard\na rotation angle and elongation of kirigami as the order parameter and the\ninverse temperature, respectively. The present study opens a new avenue in\nphysics, pointing out the importance of the distinction between discontinuity\nand continuity of the high-extensibility transition in an elementary kirigami\nstructure, and showing that the mechanical response of kirigami can be\nunderstood using the tools of statistical physics, which have been proved to be\nuseful in many fields of physics.",
        "positive": "Peeling dynamics of fluid membranes bridged by molecular bonds: moving\n  or breaking: Biological adhesion is a critical mechanical function of complex organisms\noperating at multiple scales. At the cellular scale, cell-cell adhesion is\nremarkably tunable to enable both cohesion and malleability during development,\nhomeostasis and disease. Such adaptable adhesion is physically supported by\ntransient bonds between laterally mobile molecules embedded in fluid membranes.\nThus, unlike specific adhesion at solid-solid or solid-fluid interfaces,\npeeling at fluid-fluid interfaces can proceed by breaking bonds, by moving\nbonds, or by a combination of both. How the additional degree of freedom\nprovided by bond mobility changes the mechanics of peeling is not understood.\nTo address this, we develop a theoretical model coupling self-consistently\ndiffusion, reactions and mechanics. Lateral mobility and reaction rates\ndetermine distinct peeling regimes. In a diffusion-dominated Stefan-like\nregime, bond motion establishes self-stabilizing dynamics that increase the\neffective adhesion fracture energy. A reaction-dominated regime exhibits\ntraveling peeling solutions where small-scale diffusion and marginal unbinding\ncontrol peeling speed. In a mixed reaction-diffusion regime, strengthening by\nbond motion competes with weakening by bond breaking in a force-dependent\nmanner, defining the strength of the adhesion patch. In turn, patch strength\ndepends on molecular properties such as bond stiffness, force sensitivity, or\ncrowding. We thus establish the physical rules enabling tunable cohesion in\ncellular tissues and in engineered biomimetic systems."
    },
    {
        "anchor": "Resolving distribution of relaxation times in Poly(propylene glycol) on\n  the crossover region: In this paper, a recently developed numerical technique [{\\em Tuncer E and\nGuba{\\'n}ski S M, IEEE Trans Diel El Insul {\\bf 8}(3)(2001) 310-320}] is\napplied to poly(propylene glycol) complex dielectric data to extract more\ninformation about the molecular relaxation processes. The method is based on a\nconstrained-least-squares (\\clsq) data fitting procedure together with the\nMonte Carlo (\\mc) method. We preselect the number of relaxation times with no\n{\\em a-priori} physical assumption, and use the Debye single relaxation as\n``kernel'', then the obtained weighting factors at each \\mc step from the \\clsq\nmethod builds up a relaxation time spectrum. When the analysis is repeated for\ndata at different temperatures a {\\em relaxation-image} is created. The\nobtained relaxation are analyzed using the Lorentz (Cauchy) distribution, which\nis a special form of the L{\\'e}vy statistics. In the present report the $\\beta$\nand $\\alpha$ relaxations are resolved for the \\ppg. A comparison of the\nrelaxations to those earlier reported in the literature indicate that the\npresented method provides additional information compared to methods based on\nempirical formulas. The distribution of relaxation times analysis is especially\nuseful to probe the crossover region where the $\\alpha$- and $\\beta$-\nrelaxations merge and the results show that the relaxation after the crossover\nregion at higher temperatures is Arrhenius-type as the $\\beta$-relaxation.\nMoreover, this relaxation is more likely to be the continuation of the\n$\\beta$-relaxation, but with a different activation energy.",
        "positive": "Microscopic calculations on Raman scattering from acousitc phonons\n  confined in Si nanocrystals: Raman scattering from the acoustic phonons confied in si nanocrystals is\ninvestigated by a microscopic lattice-dynamical calculation. Polarized and\ndepolarized spectra are found to be rather different, indicated from different\nacoustic phonons. The polarized scattering is more pronounced than the\ndepolarized one. The calculated results are compared with the recent\nexperimental data. The matrix effects are discussed."
    },
    {
        "anchor": "Unified rheology of vibro-fluidized dry granular media: From slow dense\n  flows to fast gas-like regimes: Granular media take on great importance in industry and geophysics, posing a\nsevere challenge to materials science. Their response properties elude known\nsoft rheological models, even when the yield-stress discontinuity is blurred by\nvibro-fluidization. Here we propose a broad rheological scenario where average\nstress sums up a frictional contribution, generalizing conventional\n$\\mu(I)$-rheology, and a kinetic collisional term dominating at fast\nfluidization. Our conjecture fairly describes a wide series of experiments in a\nvibrofluidized vane setup, whose phenomenology includes velocity weakening,\nshear thinning, a discontinuous thinning transition, and gaseous shear\nthickening. The employed setup gives access to dynamic fluctuations, which\nexhibit a broad range of timescales. In the slow dense regime the frequency of\ncage-opening increases with stress and enhances, with respect to\n$\\mu(I)$-rheology, the decrease of viscosity. Diffusivity is exponential in the\nshear stress in both thinning and thickening regimes, with a huge growth near\nthe transition.",
        "positive": "Slip flow over structured surfaces with entrapped microbubbles: On hydrophobic surfaces, roughness may lead to a transition to a\nsuperhydrophobic state, where gas bubbles at the surface can have a strong\nimpact on a detected slip. We present two-phase lattice Boltzmann simulations\nof a Couette flow over structured surfaces with attached gas bubbles. Even\nthough the bubbles add slippery surfaces to the channel, they can cause\nnegative slip to appear due to the increased roughness. The simulation method\nused allows the bubbles to deform due to viscous stresses. We find a decrease\nof the detected slip with increasing shear rate which is in contrast to some\nrecent experimental results implicating that bubble deformation cannot account\nfor these experiments. Possible applications of bubble surfaces in microfluidic\ndevices are discussed."
    },
    {
        "anchor": "Depletion-induced biaxial nematic states of boardlike particles: With the aim of investigating the stability conditions of biaxial nematic\nliquid crystals, we study the effect of adding a non-adsorbing ideal depletant\non the phase behavior of colloidal hard boardlike particles. We take into\naccount the presence of the depletant by introducing an effective depletion\nattraction between a pair of boardlike particles. At fixed depletant fugacity,\nthe stable liquid crystal phase is determined through a mean-field theory with\nrestricted orientations. Interestingly, we predict that for slightly elongated\nboardlike particles a critical depletant density exists, where the system\nundergoes a direct transition from an isotropic liquid to a biaxial nematic\nphase. As a consequence, by tuning the depletant density, an easy experimental\ncontrol parameter, one can stabilize states of high biaxial nematic order even\nwhen these states are unstable for pure systems of boardlike particles.",
        "positive": "The polymer theta-point as a knot delocalisation transition: We study numerically the tightness of prime flat knots in a model of\nself-attracting polymers with excluded volume. We find that these knots are\nlocalised in the high temperature swollen regime, but become delocalised in the\nlow temperature globular phase. Precisely at the collapse transition, the knots\nare weakly localised. Some of our results can be interpreted in terms of the\ntheory of polymer networks, which allows to conjecture exact exponents for the\nknot length probability distributions."
    },
    {
        "anchor": "Transition to spatially periodic patterns in nematics under oscillatory\n  shear flow: linear analysis: We consider the orientational instabilities, both homogeneous and spatially\nperiodic, developing in a nematic liquid crystal under rectilinear oscillatory\nCouette flow for director alignment perpendicular to the flow plane. Using\nnumerical and analytical approaches we determine the critical amplitude of\noscillatory flow instabilities, the critical wave number and the symmetry of\nthe destabilizing mode. It was found, that by varying of the oscillatory flow\nfrequency the instability changes its temporal symmetry. The mechanism of this\ntransition is coupled with the inertia of the nematic fluid. We also shown that\nan electric field applied to the nematic layer can induce switching between\ninstabilities with different spatial and temporal symmetries. The complete\nphase diagram of the flow instabilities is presented",
        "positive": "Thermal fluctuations and osmotic stability of lipid vesicles: Biological membranes constantly change their shape in response to external\nstimuli, and understanding the remodeling and stability of vesicles in\nheterogeneous environments is therefore of fundamental importance for a range\nof cellular processes. One crucial question is how vesicles respond to external\nosmotic stresses, imposed by differences in solute concentrations between the\nvesicle interior and exterior. Previous analyses of the membrane bending energy\nhave predicted that micron-sized giant unilamellar vesicles (GUVs) should\nbecome globally deformed already for nanomolar concentration differences, in\ncontrast to experimental findings that find deformations at much higher osmotic\nstresses. In this article, we analyze the mechanical stability of a spherical\nvesicle exposed to an external osmotic pressure in a statistical-mechanical\nmodel, including the effect of thermally excited membrane bending modes. We\nfind that the inclusion of thermal fluctuations of the vesicle shape changes\nrenders the vesicle deformation continuous, in contrast to the abrupt\ntransition in the athermal picture. Crucially, however, the predicted critical\npressure associated with global vesicle deformation remains the same as when\nthermal fluctuations are neglected, approximately six orders of magnitude\nsmaller than the typical collapse pressure recently observed experimentally for\nGUVs. We conclude by discussing possible sources of this persisting dissonance\nbetween theory and experiments."
    },
    {
        "anchor": "Steady-State Luminescence of Polymers: Effects of Flow and of\n  Hydrodynamic Interactions: We consider a simple model for steady-state luminescence of single polymer\nchains in a dilute solution in the case when excitation quenching is due to\nenergy transfer between a donor and an acceptor attached to the ends of the\nchain. We present numerical results for Rouse chains without or with\nhydrodynamic interactions, which are taken into account in a perturbative\nmanner. We consider the situations of a quiescent solvent as well as the chain\nin a shear flow and discuss the dependence of the steady-state luminescence\nintensity on the strength of hydrodynamic interaction and on the shear rate in\nthe flow.",
        "positive": "Scaling of liquid-drop impact craters in wet granular media: Combining high-speed photography with laser profilometry, we study the\ndynamics and the morphology of liquid-drop impact cratering in wet granular\nmedia---a ubiquitous phenomenon relevant to many important geological,\nagricultural, and industrial processes. By systematically investigating\nimportant variables such as impact energy, the size of impinging drops and the\ndegree of liquid saturation in granular beds, we uncover a novel scaling for\nthe size of impact craters. We show that this scaling can be explained by\nconsidering the balance between the inertia of impinging drops and the strength\nof impacted surface. Such a theoretical understanding confirms that the unique\nenergy partition originally proposed for liquid-drop impact cratering in dry\ngranular media also applies for impact cratering in wet granular media.\nMoreover, we demonstrate that compressive stresses, instead of shear stresses,\ncontrol granular impact cratering. Our study enriches the picture of generic\ngranular impact cratering and sheds light on the familiar phenomena of raindrop\nimpacts in granular media."
    },
    {
        "anchor": "Entangled quantum tunneling of two-component Bose-Einstein condensates: We examine the quantum tunneling process in Bose condensates of two\ninteracting species trapped in a double well configuration. We discover the\ncondition under which particles of different species can tunnel as pairs\nthrough the potential barrier between two wells in opposition directions. This\nnovel form of tunneling is due to the interspecies interaction that eliminates\nthe self- trapping effect. The correlated motion of tunneling atoms leads to\nthe generation of quantum entanglement between two macroscopically coherent\nsystems.",
        "positive": "Susceptibility functions for slow relaxation processes in supercooled\n  liquids and the search for universal relaxation patterns: In order to describe the slow response of a glass former we discuss some\ndistribution of correlation times, e.g., the generalized gamma distribution\n(GG) and an extension thereof (GGE), the latter allowing to reproduce a simple\npeak susceptibility such as of Cole-Davidson type as well as a susceptibility\nexhibiting an additional high frequency power law contribution (excess wing).\nApplying the GGE distribution to the dielectric spectra of glass formers\nexhibiting no beta-process peak (glycerol, propylene carbonate and picoline) we\nare able to reproduce the salient features of the slow response (1e-6 Hz - 1e9\nHz). A line shape analysis is carried out either in the time or frequency\ndomain and in both cases an excess wing can be identified. The latter evolves\nin a universal way while cooling and shows up for correlation times tau_alpha >\n1e-8 s. It appears that its first emergence marks the break down of the high\ntemperature scenario of mode coupling theory. - In order to describe a glass\nformer exhibiting a beta-process peak we have introduced a distribution\nfunction which is compatible with assuming a thermally activated process in\ncontrast to some commonly used fit functions. Together with the GGE\ndistribution this function allows in the frame of the Williams-Watts approach\nto completely interpolate the spectra, e.g. of fluoro aniline (1e-6 Hz - 1e9\nHz). The parameters obtained indicate an emergence of both the excess wing and\nthe beta-process again at tau_alpha > 1e-8s."
    },
    {
        "anchor": "A Conditionally Cubic-Gaussian Stochastic Lagrangian Model for\n  Acceleration in Isotropic Turbulence: The modelling of fluid particle accelerations in homogeneous, isotropic\nturbulence in terms of second-order stochastic models for the Lagrangian\nvelocity is considered. The basis for the Reynolds model (A. M. Reynolds,\n\\textit{Phys. Rev. Lett.} $\\mathbf{91}(8)$, 084503 (2003)) is reviewed and\nexamined by reference to DNS data. In particular, we show DNS data that support\nstochastic modelling of the logarithm of pseudo-dissipation as an\nOrnstein-Uhlenbeck process (Pope and Chen 1990) and reveal non-Gaussianity of\nthe conditional acceleration PDF. The DNS data are used to construct a simple\nstochastic model that is exactly consistent with Gaussian velocity and\nconditionally cubic-Gaussian acceleration statistics. This model captures the\neffects of intermittency of dissipation on acceleration and the conditional\ndependence of acceleration on pseudo-dissipation (which differs from that\npredicted by the refined Kolmogorov (1962) hypotheses). Non-Gaussianity of the\nconditional acceleration PDF is accounted for in terms of model nonlinearity.\nThe diffusion coefficient for the new model is chosen based on DNS data for\nconditional two-time velocity statistics. The resulting model predictions for\nconditional and unconditional velocity statistics and timescales are shown to\nbe in good agreement with DNS data.",
        "positive": "Reaction-limited Colloidal Aggregation Induced by Salt and Inert\n  Polymers: Salt-induced aggregation of 20 nm colloidal silica is followed by light\ntransmission, which shows an a kinetic form exp[-(t/t_0)^{\\alpha}], where\n\\alpha = 2.6 and t_0 is an empirical time constant which reflects the colloidal\nstability. We found a power law dependence of t_0 on ionic strength, which can\nbe explained by the classical DLVO theory. The neutral polymers polyethylene\nglycol (PEG) accelerate the aggregation rate, and those with higher molecular\nweight are more effective in inducing the aggregation with similar stretched\nexponential form of kinetics. Current theories of polymer-mediated interactions\nprovide a reasonable interpretation of the effect of PEG. The stretched\nexponential kinetics of the light transmission is found to be consistent with a\ncluster-size dynamic scaling model of aggregation."
    },
    {
        "anchor": "Creating equilibrium glassy states via random particle bonding: Creating amorphous solid states by randomly bonding an ensemble of dense\nliquid monomers is a common procedure which is applied to create a variety of\nmaterials such as epoxy resins, colloidal gels, and vitrimers. The properties\nof the resulting solid do, however, {\\it a priori} strongly depend on the\npreparation history. This can lead to substantial aging of the material, i.e.,\nproperties such as mechanical moduli and transport coefficients depend on the\ntime elapsed since solidification, which can lead to a slow degradation of the\nmaterial in technological applications. It is therefore important to understand\nunder which conditions random monomer bonding can lead to stable solid states,\ni.e., long-lived metastable states whose properties do not change over time. In\nthis work, we present a theoretical and computational analysis of this problem,\nand introduce a random bonding procedure that guarantees the proper\nequilibration of the resulting amorphous states. Our procedure also provides a\nnew route to investigate the fundamental properties of glassy energy landscapes\nby producing translationally-invariant ultrastable glassy states of simple\nparticle models.",
        "positive": "Non-Kramers Freezing and Unfreezing of Tunneling in the Biaxial Spin\n  Model: The ground state tunnel splitting for the biaxial spin model in the magnetic\nfield, H = -D S_{x}^2 + E S_{z}^2 - g \\mu_B S_z H_z, has been investigated\nusing an instanton approach. We find a new type of spin instanton and a new\nquantum interference phenomenon associated with it: at a certain field, H_2 =\n2SE^{1/2}(D+E)^{1/2}/(g \\mu_B), the dependence of the tunneling splitting on\nthe field switches from oscillations to a monotonic growth. The predictions of\nthe theory can be tested in Fe_8 molecular nanomagnets."
    },
    {
        "anchor": "Plasmonic Microbubble Dynamics in Binary Liquids: The growth of surface plasmonic microbubbles in binary water/ethanol\nsolutions is experimentally studied. The microbubbles are generated by\nilluminating a gold nanoparticle array with a continuous wave laser. Plasmonic\nbubbles exhibit ethanol concentration-dependent behaviors. For low ethanol\nconcentrations (f_e) of < 67.5%, bubbles do not exist at the solid-liquid\ninterface. For high f_e values of >80%, the bubbles behave as in pure ethanol.\nOnly in an intermediate window of 67.5% < f_e < 80% do we find sessile\nplasmonic bubbles with a highly nontrivial temporal evolution, in which as a\nfunction of time three phases can be discerned. (1) In the first phase, the\nmicrobubbles grow, while wiggling. (2) As soon as the wiggling stops, the\nmicrobubbles enter the second phase in which they suddenly shrink, followed by\n(3) a steady reentrant growth phase. Our experiments reveal that the sudden\nshrinkage of the microbubbles in the second regime is caused by a depinning\nevent of the three phase contact line. We systematically vary the ethanol\nconcentration, laser power, and laser spot size to unravel water recondensation\nas the underlying mechanism of the sudden bubble shrinkage in phase 2.",
        "positive": "Elasticity of semiflexible polymers in two dimensions: We study theoretically the entropic elasticity of a semi-flexible polymer,\nsuch as DNA, confined to two dimensions. Using the worm-like-chain model we\nobtain an exact analytical expression for the partition function of the polymer\npulled at one end with a constant force. The force-extension relation for the\npolymer is computed in the long chain limit in terms of Mathieu characteristic\nfunctions. We also present applications to the interaction between a\nsemi-flexible polymer and a nematic field, and derive the nematic order\nparameter and average extension of the polymer in a strong field."
    },
    {
        "anchor": "Construction of nuclear envelope shape by a high-genus vesicle with\n  pore-size constraint: Nuclear pores have an approximately uniform distribution in the nuclear\nenvelope of most living cells. Hence, the morphology of the nuclear envelope is\na spherical stomatocyte with a high genus. We have investigated the morphology\nof high-genus vesicles under pore-size constraint using dynamically\ntriangulated membrane simulations. Bending-energy minimization without volume\nor other constraints produces a circular-cage stomatocyte, where the pores are\naligned in a circular line on an oblate bud. As the pore radius is reduced, the\ncircular-pore alignment is more stabilized than a random pore distribution on a\nspherical bud. However, we have clarified the conditions for the formation of a\nspherical stomatocyte: a small perinuclear volume, osmotic pressure within\nnucleoplasm, and repulsion between the pores. When area-difference elasticity\nis taken into account, the formation of cylindrical or budded tubules from the\nstomatocyte and discoidal stomatocyte is found.",
        "positive": "Structure formation of surfactant membranes under shear flow: Shear-flow-induced structure formation in surfactant-water mixtures is\ninvestigated numerically using a meshless-membrane model in combination with a\nparticle-based hydrodynamics simulation approach for the solvent. At low shear\nrates, uni-lamellar vesicles and planar lamellae structures are formed at small\nand large membrane volume fractions, respectively. At high shear rates,\nlamellar states exhibit an undulation instability, leading to rolled or\ncylindrical membrane shapes oriented in the flow direction. The spatial\nsymmetry and structure factor of this rolled state agree with those of\nintermediate states during lamellar-to-onion transition measured by\ntime-resolved scatting experiments. Structural evolution in time exhibits a\nmoderate dependence on the initial condition."
    },
    {
        "anchor": "A mechanism for air induced fluidization in vibrated granular beds: We present a new mechanism for the fluidization of a vibrated granular bed in\nthe presence of interstitial air. We show that the air flow induced across the\nbed, as the gap in the bottom of the cell evolves, can fluidize the bed in a\nsimilar way as in gas-fluidized {\\it static} beds. We use the model of Kroll to\nquantify the relevant variables suggested by the mechanism proposed. The\nrelevance of the above fluidization for segregation phenomena is discussed.",
        "positive": "Hidden Complexity in the Isomerization Dynamics of Holliday Junctions: A plausible consequence of rugged energy landscapes of biomolecules is that\nfunctionally competent folded states may not be unique, as is generally\nassumed. Indeed, molecule-to-molecule variations in the dynamics of enzymes and\nribozymes under folding conditions have recently been identified in single\nmolecule experiments. However, systematic quantification and the structural\norigin of the observed complex behavior remain elusive. Even for a relatively\nsimple case of isomerization dynamics in Holliday Junctions (HJs), molecular\nheterogeneities persist over a long observation time (Tobs ~ 40 sec). Here,\nusing concepts in glass physics and complementary clustering analysis, we\nprovide a quantitative method to analyze the smFRET data probing the\nisomerization in HJ dynamics. We show that ergodicity of HJ dynamics is\neffectively broken; as a result, the conformational space of HJs is partitioned\ninto a folding network of kinetically disconnected clusters. While\nisomerization dynamics in each cluster occurs rapidly as if the associated\nconformational space is fully sampled, distinct patterns of time series\nbelonging to different clusters do not interconvert on Tobs. Theory suggests\nthat persistent heterogeneity of HJ dynamics is a consequence of internal\nmultiloops with varying sizes and flexibilities frozen by Mg2+ ions. An\nannealing experiment using Mg2+ pulse that changes the Mg2+ cocentration from\nhigh to low to high values lends support to this idea by explicitly showing\nthat interconversions can be driven among trajectories with different patterns."
    },
    {
        "anchor": "Hard competition: stabilizing the elusive biaxial nematic phase in\n  suspensions of colloidal particles with extreme lengths: We use computer simulations to study the existence and stability of a biaxial\nnematic $N_b$ phase in systems of hard polyhedral cuboids, triangular prisms,\nand rhombic platelets, characterized by a long ($L$), medium ($M$), and short\n($S$) particle axis. For all three shape families, we find stable $N_b$ states\nprovided the shape is not only close to the so-called dual shape with $M =\n\\sqrt{LS}$ but also sufficiently anisotropic with $L/S>9,11,14, 23$ for rhombi,\nprisms, and cuboids, respectively, corresponding to anisotropies not considered\nbefore. Surprisingly, a direct isotropic-$N_b$ transition does not occur in\nthese systems due to a destabilization of $N_b$ by a smectic (for cuboids and\nprisms) or a columnar (for platelets) phase at small $L/S$, or by an\nintervening uniaxial nematic phase at large $L/S$. Our results are confirmed by\na density functional theory provided the third virial coefficient is included\nand a continuous rather than a discrete (Zwanzig) set of particle orientations\nis taken into account.",
        "positive": "Density Fluctuations in Granular Piles Traversing the Glass Transition:\n  A Grain-Scale Characterization of the Transition via the Internal Energy: The transition into a glassy state of the ensemble of static, mechanically\nstable configurations of a tapped granular pile is explored using extensive\nmolecular dynamics simulations. We show that different horizontal sub-regions\n(\"layers\") along the height of the pile traverse this transition in a similar\nmanner but at distinct tap intensities. We supplement the conventional approach\nbased purely on properties of the static configurations with investigations of\nthe grain-scale dynamics by which the tap energy is transmitted throughout the\npile. We find that the effective energy that particles dissipate is a function\nof each particle's location in the pile and, moreover, that its value plays a\ndistinctive role in the transformation between configurations. This internal\nenergy provides a \"temperature-like\" parameter that allows us to align the\ntransition into the glassy state for all layers, as well as different annealing\nschedules, at a critical value."
    },
    {
        "anchor": "Interparticle friction leads to non-monotonic flow curves and hysteresis\n  in viscous suspensions: Hysteresis is a major feature of the solid-liquid transition in granular\nmaterials. This property, by allowing metastable states, can potentially yield\ncatastrophic phenomena such as earthquakes or aerial landslides. The origin of\nhysteresis in granular flows is still debated. However, most mechanisms put\nforward so far rely on the presence of inertia at the particle level. In this\npaper, we study the avalanche dynamics of non-Brownian suspensions in slowly\nrotating drums and reveal large hysteresis of the avalanche angle even in the\nabsence of inertia. By using micro-silica particles whose interparticle\nfriction coefficient can be turned off, we show that microscopic friction,\nconversely to inertia, is key to triggering hysteresis in granular suspensions.\nTo understand this link between friction and hysteresis, we use the rotating\ndrum as a rheometer to extract the suspension rheology close to the flow onset\nfor both frictional and frictionless suspensions. This analysis shows that the\nflow rule for frictionless particles is monotonous and follows a power law of\nexponent $\\alpha \\!= \\! 0.37 \\pm 0.05$, in close agreement with the previous\ntheoretical prediction, $\\alpha\\!=\\! 0.35$. By contrast, the flow rule for\nfrictional particles suggests a velocity-weakening behavior, thereby explaining\nthe flow instability and the emergence of hysteresis. These findings show that\nhysteresis can also occur in particulate media without inertia, questioning the\nintimate nature of this phenomenon. By highlighting the role of microscopic\nfriction, our results may be of interest in the geophysical context to\nunderstand the failure mechanism at the origin of undersea landslides.",
        "positive": "The mechanics and thermodynamics of tubule formation in biological\n  membranes: Membrane tubulation is a ubiquitous process that occurs both at the plasma\nmembrane and on the membranes of intracellular organelles. These tubulation\nevents are known to be mediated by forces applied on the membrane either due to\nmotor proteins, by polymerization of the cytoskeleton, or due to the\ninteractions between membrane proteins binding onto the membrane. The numerous\nexperimental observations of tube formation have been amply supported by\nmathematical modeling of the associated membrane mechanics and have provided\ninsights into the force-displacement relationships of membrane tubes. Recent\nadvances in quantitative biophysical measurements of membrane-protein\ninteractions and tubule formation have necessitated the need for advances in\nmodeling that will account for the interplay of multiple aspects of physics\nthat occur simultaneously. Here, we present a comprehensive review of\nexperimental observations of tubule formation and provide context from the\nframework of continuum modeling. Finally, we explore the scope for future\nresearch in this area with an emphasis on iterative modeling and experimental\nmeasurements that will enable us to expand our mechanistic understanding of\ntubulation processes in cells."
    },
    {
        "anchor": "Active Membrane Fluctuations Studied by Micropipet Aspiration: We present a detailed analysis of the micropipet experiments recently\nreported in J-B. Manneville et al., Phys. Rev. Lett. 82, 4356--4359 (1999),\nincluding a derivation of the expected behaviour of the membrane tension as a\nfunction of the areal strain in the case of an active membrane, i.e.,\ncontaining a nonequilibrium noise source. We give a general expression, which\ntakes into account the effect of active centers both directly on the membrane,\nand on the embedding fluid dynamics, keeping track of the coupling between the\ndensity of active centers and the membrane curvature. The data of the\nmicropipet experiments are well reproduced by the new expressions. In\nparticular, we show that a natural choice of the parameters quantifying the\nstrength of the active noise explains both the large amplitude of the observed\neffects and its remarkable insensitivity to the active-center density in the\ninvestigated range. [Submitted to Phys Rev E, 22 March 2001]",
        "positive": "A structurally frame-indifferent model for anisotropic\n  visco-hyperelastic materials: One of the main theoretical issues in developing a theory of anisotropic\nviscoelastic media at finite strains lies in the proper definition of the\nmaterial symmetry group and its evolution with time. In this paper the matter\nis discussed thoroughly and addressed by introducing a novel anisotropic\nremodelling equation compatible with the principle of structural frame\nindifference, a requirement that every inelastic theory based on the\nmultiplicative decomposition of the deformation gradient must obey to. The\nevolution laws of the dissipative process are %obtained by introducing a novel\n(remodelling) balance equation which is completely determined by two scalar\nfunctions, the elastic strain energy and the dissipation densities. The proper\nchoice of the dissipation function allows us to reduce the proposed model to\nthe Ericksen anisotropic fluid, when deformation is sufficiently slow, or to\nthe anisotropic hyperelastic solid for fast deformations. Finally, a few\nprototype examples are discussed to highlight the role of the relaxation times\nin the constitutive response."
    },
    {
        "anchor": "Fluctuations of particle motion in granular avalanches - from the\n  microscopic to the macroscopic scales: In this study, we have investigated the fluctuations of particle motion, i.e.\nthe non-affine motion, during the avalanche process, discovering a rich\ndynamics from the microscopic to the macroscopic scales. We find that there is\nstrong correlation between the magnitude of the velocity fluctuation and the\nvelocity magnitude in the spatial and temporal domains. The possible connection\nbetween this finding and STZ is discussed based on the direct measurement of\nthe T1 events. In addition, the velocity magnitude of the system and the stress\nfluctuations of the system are strongly correlated temporally. Our finding will\npose challenges to the development of more rigorous theories to describe the\navalanche dynamics based on the microscopic approach. Moreover, our finding\npresents a plausible mechanism of the particle entrainment in a simple system.",
        "positive": "Critical adsorption and critical Casimir forces for geometrically\n  structured confinements: We study the behavior of fluids, confined by geometrically structured\nsubstrates, upon approaching a critical point at T = Tc in their bulk phase\ndiagram. As generic substrate structures periodic arrays of wedges and ridges\nare considered. Based on general renormalization group arguments we calculate,\nwithin mean field approximation, the universal scaling functions for order\nparameter profiles of a fluid close to a single structured substrate and\ndiscuss the decay of its spatial variation into the bulk. We compare the excess\nadsorption at corrugated substrates with the one at planar walls. The\nconfinement of a critical fluid by two walls generates effective critical\nCasimir forces between them. We calculate corresponding universal scaling\nfunctions for the normal critical Casimir force between a flat and a\ngeometrically structured substrate as well as the lateral critical Casimir\nforce between two identically patterned substrates."
    },
    {
        "anchor": "Single-Trajectory Characterization of Active Swimmers in a Flow: We develop a maximum likelihood method to infer relevant physical properties\nof elongated active particles. Using individual trajectories of advected\nswimmers as input, we are able to accurately determine their rotational\ndiffusion coefficients and an effective measure of their aspect ratio, also\nproviding reliable estimators for the uncertainties of such quantities. We\nvalidate our theoretical construction using numerically generated active\ntrajectories upon no-flow, simple shear, and Poiseuille flow, with excellent\nresults. Being designed to rely on single-particle data, our method eases\napplications in experimental conditions where swimmers exhibit a strong\nmorphological diversity. We briefly discuss some of such ongoing experimental\napplications, specifically, in the characterization of swimming E.coli in a\nflow.",
        "positive": "Elastic turbulence in shear banding wormlike micelles: We study the dynamics of the Taylor-Couette flow of shear banding wormlike\nmicelles. We focus on the high shear rate branch of the flow curve and show\nthat for sufficiently high Weissenberg numbers, this branch becomes unstable.\nThis instability is strongly sub-critical and is associated with a shear stress\njump. We find that this increase of the flow resistance is related to the\nnucleation of turbulence. The flow pattern shows similarities with the elastic\nturbulence, so far only observed for polymer solutions. The unstable character\nof this branch led us to propose a scenario that could account for the recent\nobservations of Taylor-like vortices during the shear banding flow of wormlike\nmicelles."
    },
    {
        "anchor": "Driven translocation of a semi-flexible polymer through a nanopore: We study the driven translocation of a semi-flexible polymer through a\nnanopore by means of a modified version of the iso-flux tension propagation\ntheory (IFTP), and extensive molecular dynamics (MD) simulations. We show that\nin contrast to fully flexible chains, for semi-flexible polymers with a finite\npersistence length $\\tilde{\\ell}_p$ the {\\it trans} side friction must be\nexplicitly taken into account to properly describe the translocation process.\nIn addition, the scaling of the end-to-end distance $R_N$ as a function of the\nchain length $N$ must be known. To this end, we first derive a semi-analytic\nscaling form for $R_N$, which reproduces the limits of a rod, an ideal chain,\nand an excluded volume chain in the appropriate limits. We then quantitatively\ncharacterize the nature of the {\\it trans} side friction based on MD\nsimulations of semi-flexible chains. Augmented with these two factors, the\nmodified IFTP theory shows that there are three main regimes for the scaling of\nthe average translocation time $\\tau \\propto N^{\\alpha}$. In the stiff chain\n(rod) limit $N/\\tilde{\\ell}_p \\ll 1$, {$\\alpha = 2$}, which continuously\ncrosses over in the regime $ 1 < N/\\tilde{\\ell}_p < 4$ towards the ideal chain\nbehavior with {$\\alpha = 3/2$}, which is reached in the regime\n$N/\\tilde{\\ell}_p \\sim 10^2$. Finally, in the limit $N/\\tilde{\\ell}_p \\gg 10^6$\nthe translocation exponent approaches its symptotic value $1+\\nu$, where $\\nu$\nis the Flory exponent. Our results are in good agreement with available\nsimulations and experimental data.",
        "positive": "Applications of computational geometry to the molecular simulation of\n  interfaces: The identification of the interfacial molecules in fluid-fluid equilibrium is\na long-standing problem in the area of simulation. We here propose a new point\nof view, making use of concepts taken from the field of computational geometry,\nwhere the definition of the \"shape\" of a set of point is a well-known problem.\nIn particular, we employ the $\\alpha$-shape construction which, applied to the\npositions of the molecules, selects a shape and identifies its boundary points,\nwhich we will take to define our interfacial molecules. A single parameter\nneeds to be fixed (the \"$\\alpha$\" of the $\\alpha$-shape), and several proposals\nare examined, all leading to very similar choices. Results of this methodology\nare evaluated against previous proposals, and seen to be reasonable."
    },
    {
        "anchor": "Flow-injection of branched polymers inside nanopores: Flexible chains (linear or branched) can be forced to enter into a narrow\ncapillary by using a hydrodynamic flow. Here, we correct our earlier\ndescription of this problem by considering the progressive nature of the\nsuction process. We find that the critical current for penetration, $J\\_c$, is\ncontrolled by the entry of a single blob of the capillary size, and that its\nscaling structure is the same for branched and linear chains.",
        "positive": "Short pitch structures in smectics with interactions over more than two\n  layers: Phenomenological model of chiral polar smectics is introduced with\ninteractions up to the fourth neighboring layers. The minimization of the free\nenergy gives three stable structures: the ferroelectric Sm C$^*$ phase, the\nantiferroelectric Sm C$^*_A$ phase and the hellicoidally modulated structure of\nthe Sm C$^*_H$ phase. The phase Sm C$^*_\\alpha$ can be recognized as the Sm\nC$^*_H$ phase below Sm A phase and as the Sm C$^*_{FI2}$ phase or as the Sm\nC$^*_{FI1}$ phase when appearing between the Sm C$^*$ phase and the Sm C$^*_A$\nphase. Stability of these phases is analyzed and the phase diagram in the space\nof model parameters is presented."
    },
    {
        "anchor": "Emergent Probability - A directed Scale-Free Network Approach to\n  Lonergan's Generic Model of Development: An intriguing heuristic model of development, decline, and change conceived\nby Bernard J.F. Lonergan (BL) in the late 1940's was laid out in a manner now\nrecognizable as representing an early model of complexity. This report is a\nfirst effort toward eventually translating that qualitative vision, designated\nEmergent Probability, into a viable network computer program.\n  In his study of human understanding, Lonergan saw the task of constructing a\ncohesive body of explanatory knowledge as a convoluted building process of\nschemes of recurrence that act as foundational elements to further growth.\nAlthough BL's kernal recurrent scheme was composed of the cognitional dynamics\nsurrounding Insight, other examples abound in nature: resource cycles, motor\nskills, biological routines, autocatalytic processes, etc. The corresponding\ngrowing generic World Process can alternatively be thought of as chemical,\nenvironmental, evolutionary, social, organizational, economical, psychological,\nor ethical, and its generality might be of particular interest to complex\nsystems researchers.",
        "positive": "The kinetics of the ice-water interface from ab initio machine learning\n  simulations: Molecular simulations employing empiric force fields have provided valuable\nknowledge about the ice growth process in the last decade. The development of\nnovel computational techniques allows us to study this process, which requires\nlong simulations of relatively large systems, with ab initio accuracy. In this\nwork, we use a neural-network potential for water trained on the Revised\nPerdew-Burke-Ernzerhof functional to describe the kinetics of the ice-water\ninterface. We study both ice melting and growth processes. Our results for the\nice growth rate are in reasonable agreement with previous experiments and\nsimulations. We find that the kinetics of ice melting presents a different\nbehavior (monotonic) than that of ice growth (non-monotonic). In particular, a\nmaximum in the ice growth rate of 6.5 {\\AA}/ns is found at 14 K of\nsupercooling. The effect of the surface structure is explored by investigating\nthe basal and primary and secondary prismatic facets. We use the Wilson-Frenkel\nrelation to explain these results in terms of the mobility of molecules and the\nthermodynamic driving force. Moreover, we study the effect of pressure by\ncomplementing the standard isobar with simulations at negative pressure (-1000\nbar) and at high pressure (2000 bar). We find that prismatic facets grow faster\nthan the basal one, and that pressure does not play an important role when the\nspeed of the interface is considered as a function of the difference between\nthe melting temperature and the actual one, i.e. to the degree of either\nsupercooling or overheating."
    },
    {
        "anchor": "Bistable anchoring of nematics on rough substrates: We analyze the interplay between wetting and anchoring of nematic liquid\ncrystals on disordering, e.g., rough substrates in the framework of the\nLandau-de Gennes theory, in situations of competing homeotropic and planar easy\naxes on the substrate and the nematic-isotropic (NI) interface. The phase\ndiagram for azimuthally symmetric substrates is calculated. We identify two\nregimes - a strongly coupled regime, where the wetting transition coincides\nwith an anchoring transition, and a weakly coupled regime, where the two are\nseparated. The anchoring transition is first order and switches between\nhomeotropic and planar anchoring. The two competing orientations are metastable\nover a broad parameter range. Hence such surfaces can be used to generate\nbistable surfaces.",
        "positive": "On measuring colloidal volume fractions: Hard-sphere colloids are popular as models for testing fundamental theories\nin condensed matter and statistical physics, from crystal nucleation to the\nglass transition. A single parameter, the volume fraction (phi), characterizes\nan ideal, monodisperse hard-sphere suspension. In comparing experiments with\ntheories and simulation, researchers to date have paid little attention to\nlikely uncertainties in experimentally-quoted phi values. We critically review\nthe experimental measurement of phi in hard-sphere colloids, and show that\nwhile statistical uncertainties in comparing relative values of phi can be as\nlow as 0.0001, systematic errors of 3-6% are probably unavoidable. The\nconsequences of this are illustrated by way of a case study comparing\nliterature data sets on hard-sphere viscosity and diffusion."
    },
    {
        "anchor": "Dynamics of biomembranes with active multiple-state inclusions: Nonequilibrium dynamics of biomembranes with active inclusions is considered.\nThe inclusions represent protein molecules which perform cyclic internal\nconformational motions driven by the energy brought with ATP ligands. As\nprotein conformations cyclically change, this induces hydrodynamical flows and\nalso directly affects the local curvature of a membrane. On the other hand,\nvariations in the local curvature of the membrane modify the transitions rates\nbetween conformational states in a protein, leading to a feedback in the\nconsidered system. Moreover, active inclusions can move diffusively through the\nmembrane so that surface concentration varies. The kinetic description of this\nsystem is constructed and the stability of the uniform stationary state is\nanalytically investigated. We show that, as the rate of supply of chemical\nenergy is increased above a certain threshold, this uniform state becomes\nunstable and stationary or traveling waves spontaneously develop in the system.\nSuch waves are accompanied by periodic spatial variation of membrane curvature\nand inclusion density. For typical parameter values, their characteristic\nwavelengths are of the order of hundreds of nanometers. For traveling waves,\nthe characteristic frequency is of the order of a thousand Hz or less.",
        "positive": "A coil-globule transition of a semiflexible polymer driven by the\n  addition of spherical particles: The phase behaviour of a single large semiflexible polymer immersed in a\nsuspension of spherical particles is studied. All interactions are simple\nexcluded volume interactions and the diameter of the spherical particles is an\norder of magnitude larger than the diameter of the polymer. The spherical\nparticles induce a quite long ranged depletion attraction between the segments\nof the polymer and this induces a continuous coil-globule transition in the\npolymer. This behaviour gives an indication of the condensing effect of\nmacromolecular crowding on DNA."
    },
    {
        "anchor": "A framework for analyzing hyper-viscoelastic polymers: Hyper-viscoelastic polymers have multiple areas of application including\naerospace, biomedicine, and automotive. Their mechanical responses are\ntherefore extremely important to understand, particularly because they exhibit\nstrong rate and temperature dependence, including a low temperature brittle\ntransition. Relationships between the response at various strain rates and\ntemperatures are investigated and a framework developed to predict large strain\nresponse at rates of c. 1000 s$^{-1}$ and above where experiments are\nunfeasible. A master curve of the storage modulus's rate dependence at a\nreference temperature is constructed using a DMA test of the polymer. A\nfrequency sweep spanning two decades and a temperature range from pre-glass\ntransition to pre-melt is used. A fractional derivative model is fitted to the\nexperimental data, and this model's parameters are used to derive stress-strain\nrelationships at a desired strain rate.",
        "positive": "Bose-Einstein condensates in `giant' toroidal magnetic traps: The experimental realisation of gaseous Bose-Einstein condensation (BEC) in\n1995 sparked considerable interest in this intriguing quantum fluid. Here we\nreport on progress towards the development of an 87Rb BEC experiment in a large\n(~10cm diameter) toroidal storage ring. A BEC will be formed at a localised\nregion within the toroidal magnetic trap, from whence it can be launched around\nthe torus. The benefits of the system are many-fold, as it should readily\nenable detailed investigations of persistent currents, Josephson effects, phase\nfluctuations and high-precision Sagnac or gravitational interferometry."
    },
    {
        "anchor": "Coexistence between fluid and crystalline phases of proteins in\n  photosynthetic membranes: Photosystem II (PSII) and its associated light-harvesting complex II (LHCII)\nare highly concentrated in the stacked grana regions of photosynthetic\nthylakoid membranes. Within the membrane, PSII-LHCII supercomplexes can be\narranged in disordered packings, ordered arrays, or mixtures thereof. The\nphysical driving forces underlying array formation are unknown, complicating\nattempts to determine a possible functional role for arrays in regulating light\nharvesting or energy conversion efficiency. Here we introduce a coarse-grained\nmodel of protein interactions in coupled photosynthetic membranes, focusing on\njust two particle types that feature simple shapes and potential energies\nmotivated by structural studies. Reporting on computer simulations of the\nmodel's equilibrium fluctuations, we demonstrate its success in reproducing\ndiverse structural features observed in experiments, including extended\nPSII-LHCII arrays. Free energy calculations reveal that the appearance of\narrays marks a phase transition from the disordered fluid state to a\nsystem-spanning crystal, which can easily be arrested by thermodynamic\nconstraints or slow dynamics. The region of fluid-crystal coexistence is broad,\nencompassing much of the physiologically relevant parameter regime. Our results\nsuggest that grana membranes lie at or near phase coexistence, conferring\nsignificant structural and functional flexibility to this densely packed\nmembrane protein system.",
        "positive": "Thickness-dependent secondary structure formation of tubelike polymers: By means of sophisticated Monte Carlo methods, we investigate the\nconformational phase diagram of a simple model for flexible polymers with\nexplicit thickness. The thickness constraint, which is introduced geometrically\nvia the global radius of curvature of a polymer conformation, accounts for the\nexcluded volume of the polymer and induces cooperative effects supporting the\nformation of secondary structures. In our detailed analysis of the temperature\nand thickness dependence of the conformational behavior for classes of short\ntubelike polymers, we find that known secondary-structure segments like helices\nand turns, but also ringlike conformations and stiff rods are dominant\nintrinsic topologies governing the phase behavior of such cooperative tubelike\nobjects. This shows that the thickness constraint is indeed a fundamental\nphysical parameter that allows for a classification of generic polymer\nstructures."
    },
    {
        "anchor": "Stability of liquid ridges on chemical micro- and nanostripes: We analyze the stability of sessile filaments (ridges) of nonvolatile liquids\nversus pearling in the case of externally driven flow along a chemical stripe\nwithin the framework of the thin film approximation. The ridges can be stable\nwith respect to pearling even if the contact line is not completely pinned. A\ngeneralized stability criterion for moving contact lines is provided. For large\nwavelengths and no drive, within perturbation theory, an analytical expression\nof the growth rate of pearling instabilities is derived. A numerical analysis\nshows that drive further stabilizes the ridge by reducing the growth rate of\nunstable perturbations, even though there is no complete stabilization. Hence\nthe stability criteria established without drive ensure overall stability.",
        "positive": "Chain morphology, swelling exponent, persistence length, like-charge\n  attraction, and charge distribution around a chain in polyelectrolyte\n  solutions: effects of salt concentration and ion size studied by molecular\n  dynamics simulations: Properties of polyelectrolytes in tetravalent salt solutions are intensively\ninvestigated by a coarse-grained model. The concentration of salt and the size\nof tetravalent counterions are found playing a decisive role on chain\nproperties. If the size of tetravalent counterions is compatible with the one\nof monomers, the chains show extended structures at low and at high salt\nconcentrations, whereas at intermediate salt concentrations, they acquire\ncompact and prolate structures. The swelling exponent of a chain against salt\nconcentration behaves in an analogous way as the morphological quantities.\nUnder certain condition, the electrostatics gives a negative contribution to\nthe persistence length, in companion with a salt-induced mechanical instability\nof polyelectrolytes. Nearly at the same moment, it appears like-charge\nattraction between chains. The equal size of the tetravalent ions and the\nmonomers is the optimal condition to attain the strongest attraction between\nchains and the most compact chain structure. Moreover, the ions form a\nmulti-layer organization around a chain and, thus, the integrated charge\ndistribution reveals an oscillatory behavior. The results suggest that charge\ninversion has no direct connection with redissolution of polyelectrolytes at\nhigh salt concentrations."
    },
    {
        "anchor": "Generalization of Clausius-Mossotti approximation in application to\n  short-time transport properties of suspensions: In 1983 Felderhof, Ford and Cohen gave microscopic explanation of the famous\nClausius-Mossotti formula for the dielectric constant of nonpolar dielectric.\nThey based their considerations on the cluster expansion of the dielectric\nconstant, which relates this macroscopic property with the microscopic\ncharacteristics of the system. In this article, we analyze the cluster\nexpansion of Felderhof, Ford and Cohen by performing its resummation\n(renormalization). Our analysis leads to the ring expansion for the macroscopic\ncharacteristic of the system, which is an expression alternative to the cluster\nexpansion. Using similarity of structures of the cluster expansion and the ring\nexpansion, we generalize (renormalize) the Clausius-Mossotti approximation. We\napply our renormalized Clausius-Mossotti approximation to the case of the\nshort-time transport properties of suspensions, calculating the effective\nviscosity and the hydrodynamic function with the translational self-diffusion\nand the collective diffusion coefficient. We perform calculations for\nmonodisperse hard-sphere suspensions in equilibrium with volume fraction up to\n45%. To assess the renormalized Clausius-Mossotti approximation, it is compared\nwith numerical simulations and the Beenakker-Mazur method. The results of our\nrenormalized Clausius-Mossotti approximation lead to comparable or much less\nerror (with respect to the numerical simulations), than the Beenakker-Mazur\nmethod for the volume fractions below $ \\phi \\approx 30\\% $ (apart from a small\nrange of wave vectors in hydrodynamic function). For volume fractions above\n$\\phi \\approx 30 \\%$, the Beenakker-Mazur method gives in most cases lower\nerror, than the renormalized Clausius-Mossotti approximation.",
        "positive": "Vortex nucleation by collapsing bubbles in Bose-Einstein condensates: The nucleation of vortex rings accompanies the collapse of ultrasound bubbles\nin superfluids. Using the Gross-Pitaevskii equation for a uniform condensate we\nelucidate the various stages of the collapse of a stationary spherically\nsymmetric bubble and establish conditions necessary for vortex nucleation. The\nminimum radius of the stationary bubble, whose collapse leads to vortex\nnucleation, was found to be about 28 healing lengths. The time after which the\nnucleation becomes possible is determined as a function of bubble's radius. We\nshow that vortex nucleation takes place in moving bubbles of even smaller\nradius if the motion made them sufficiently oblate."
    },
    {
        "anchor": "Glassy behavior of a homopolymer from molecular dynamics simulations: We study at- and out-of-equilibrium dynamics of a single homopolymer chain at\nlow temperature using molecular dynamics simulations. The main quantities of\ninterest are the average root mean square displacement of the monomers below\nthe theta point, and the structure factor, as a function of time. The\nobservation of these quantities show a close resemblance to those measured in\nstructural glasses and suggest that the polymer chain in its low temperature\nphase is in a glassy phase, with its dynamics dominated by traps. In\nequilibrium, at low temperature, we observe the trapping of the monomers and a\nslowing down of the overall motion of the polymer as well as non-exponential\nrelaxation of the structure factor. In out-of-equilibrium, at low temperatures,\nwe compute the two-time quantities and observe breaking of ergodicity in a\nrange of waiting times, with the onset of aging.",
        "positive": "The Extreme Mechanics of Viscoelastic Metamaterials: Mechanical metamaterials made of flexible building blocks can exhibit a\nplethora of extreme mechanical responses, such as negative elastic constants,\nshape-changes, programmability and memory. To date, dissipation has largely\nremained overlooked for such flexible metamaterials. As a matter of fact,\nextensive care has often been devoted in the constitutive materials' choice to\navoid strong dissipative effects. However, in an increasing number of\nscenarios, where metamaterials are loaded dynamically, dissipation can not be\nignored. In this review, we show that the interplay between mechanical\ninstabilities and viscoelasticity can be crucial and can be harnessed to obtain\nnew functionalities. We first show that this interplay is key to understanding\nthe dynamical behaviour of flexible dissipative metamaterials that use buckling\nand snapping as functional mechanisms. We further discuss the new opportunities\nthat spatial patterning of viscoelastic properties offer for the design of\nmechanical metamaterials with properties that depend on loading rate."
    },
    {
        "anchor": "Universal size properties of \"star-ring\" polymer structure in disordered\n  environment: We consider the complex polymer system, consisting of ring polymer connected\nto the $f_1$-branched star-like structure, in good solvent in presence of\nstructural inhomogeneities. We assume, that structural defects are correlated\nat large distances $x$ according to a power law $~x^{-a}$. Applying the direct\npolymer renormalization approach, we evaluate the universal size\ncharacteristics such as the ratio of the radii of gyration of star-ring and\nstar topologies, and compare the effective sizes of single branches in complex\nstructures and isolated polymers of the same total molecular weight. The\nnon-trivial impact of disorder on these quantities is analyzed.",
        "positive": "Pulling adsorbed polymers from surfaces with the AFM: stick versus slip,\n  peeling versus gliding: We consider the response of an adsorbed polymer that is pulled by an AFM\nwithin a simple geometric framework. We separately consider the cases of i)\nfixed polymer-surface contact point, ii) sticky case where the polymer is\npeeled off from the substrate, and iii) slippery case where the polymer glides\nover the surface. The resultant behavior depends on the value of the surface\nfriction coefficient and the adsorption strength. Our resultant force profiles\nin principle allow to extract both from non-equilibrium force-spectroscopic\ndata."
    },
    {
        "anchor": "Conformational landscape of long semiflexible linear and ring polymers\n  near attractive surfaces: Conformations of a crowded neutral semiflexible polymer under confinement\nnear an attractive wall are studied via coarse-grained simulations. We study\nthe effects of the interplay of the length of the polymer, bending rigidity,\nand the repulsive crowder density on such equilibrium semiflexible polymer\nconformations. The length of the polymer dictates the number of distinct\nconformations of the adsorbed semiflexible polymer, suggesting that previous\nstudies of short polymers are limited. The crowder density is shown to\neffectively reduce the bending rigidity of the polymers and at the highest\ncrowder density considered, a crumpled wall-adsorbed polymer conformation is\nseen regardless of the semiflexibility. In addition, we study the role of the\ntopology of the semiflexible polymer by comparing the results of linear\nsemiflexible polymers with those of ring polymers. The conformational landscape\nof crowded ring polymers shows less diversity than that of a linear polymer and\ncrowders are seen to affect the ring polymers differently than their linear\ncounterparts.",
        "positive": "Quantitative differentiation of protein aggregates from other subvisible\n  particles in viscous mixtures through holographic characterization: We demonstrate the use of holographic video microscopy to detect individual\nsubvisible particles dispersed in biopharmaceutical formulations and to\ndifferentiate them based on material characteristics measured from their\nholograms. The result of holographic analysis is a precise and accurate\nmeasurement of the concentrations and size distributions of multiple classes of\nsubvisible contaminants dispersed in the same product simultaneously. We\ndemonstrate this analytical technique through measurements on model systems\nconsisting of human IgG aggregates in the presence of common contaminants such\nas silicone oil emulsion droplets and fatty acids. Holographic video microscopy\nalso clearly identifies metal particles and air bubbles. Being able to\ndifferentiate and characterize the individual components of such heterogeneous\ndispersions provides a basis for tracking other factors that influence the\nstability of protein formulations including handling and degradation of\nsurfactant and other excipients."
    },
    {
        "anchor": "Thermally Driven Elastic Micromachines: We discuss the directional motion of an elastic three-sphere micromachine in\nwhich the spheres are in equilibrium with independent heat baths having\ndifferent temperatures. Even in the absence of prescribed motion of springs,\nsuch a micromachine can gain net motion purely because of thermal fluctuations.\nA relation connecting the average velocity and the temperatures of the spheres\nis analytically obtained. This velocity can also be expressed in terms of the\naverage heat flows in the steady state. Our model suggests a new mechanism for\nthe locomotion of micromachines in nonequilibrium biological systems.",
        "positive": "Statistical Analysis of Structural Transitions in Small Systems: We discuss general thermodynamic properties of molecular structure formation\nprocesses like protein folding by means of simplified, coarse-grained models.\nThe conformational transitions accompanying these processes exhibit\nsimilarities to thermodynamic phase transitions, but also significant\ndifferences as the systems that we investigate here are very small. The\nusefulness of a microcanonical statistical analysis of these transitions in\ncomparison with a canonical interpretation is emphasized. The results are\nobtained by employing sophisticated generalized-ensemble Markov-chain Monte\nCarlo methodologies."
    },
    {
        "anchor": "Edges control clustering in levitated granular matter: The properties of small clusters depend dramatically on the interactions\nbetween their constituent particles. However, it remains challenging to design\nand tune the interactions between macroscopic particles, such as in a granular\nmaterial. Here, we use acoustic levitation to trap macroscopic grains and\ninduce forces between them. Our main results show that particles levitated in\nan acoustic field prefer to make contact along sharp edges. The radius of\ncurvature of the edges directly controls the magnitude of these forces. These\nhighly directional interactions, combined with local contact forces, give rise\nto a diverse array of cluster shapes. Our results open up new possibilities for\nthe design of specific forces between macroscopic particles, directing their\nassembly, and actuating their motion.",
        "positive": "Predicting plasticity with soft vibrational modes: from dislocations to\n  glasses: We show that quasi localized low-frequency modes in the vibrational spectrum\ncan be used to construct soft spots, or regions vulnerable to rearrangement,\nwhich serve as a universal tool for the identification of flow defects in\nsolids. We show that soft spots not only encode spatial information, via their\nlocation, but also directional information, via directors for particles within\neach soft spot. Single crystals with isolated dislocations exhibit\nlow-frequency phonon modes that localize at the core, and their polarization\npattern predicts the motion of atoms during elementary dislocation glide in\nexquisite detail. Even in polycrystals and disordered solids, we find that the\ndirectors associated with particles in soft spots are highly correlated with\nthe direction of particle displacements in rearrangements."
    },
    {
        "anchor": "Experimental evidence of thermal-like behaviour in dense granular\n  suspensions: We experimentally investigate the statistical behaviour of a model\ntwo-dimensional granular system undergoing stationary sedimentation. Buoyant\ncylindrical particles are rotated in liquid-filled drum, thus confined in a\nharmonic centripetal potential with tunable curvature, which competes with\ngravity to produce various stationary states: though heterogeneous, the packing\nfraction of the system can be tuned to be fully dispersed to fully crystallised\nas the rotation rate is increased. We show that this dynamical system is in\nmechanical equilibrium in the confining potential and exhibits a thermal-like\nbehaviour, where the granular pressure and the packing fraction are related\nthrough an equation of state. We obtain a semi-analytical expression of the\nequation of state allowing to probe the nature of the hydrodynamic interactions\nbetween the particles. This description is valid in the whole range of the\nphysical parameters we investigated and reveals a buoyant energy scale that we\ninterpret as an effective temperature. We finally discuss the behaviour of our\nsystem at high packing fractions and the relevance of the equation of state to\nthe liquid-solid phase transition.",
        "positive": "Flow reactor for preparation of lipid nanoparticles via temperature\n  variations: Lipid nanoemulsions and nanosuspensions are used as flavor carriers and\nbubble stabilizers in soft drinks and foods, as well as delivery vehicles for\nlipophilic drugs in pharmaceutics. Common techniques for their formation are\nthe high-pressure and ultrasonic homogenizers. These techniques dissipate most\nof the input energy, which results in excessive heating and generation of free\nradicals that might modify sensitive ingredients. Low energy methods are also\nused in some applications, but they have specific limitations restricting their\nuniversal use. In the current study, we propose an alternative approach - a\nflow reactor with a variable temperature, which utilizes the lipids'\npolymorphic transitions to induce spontaneous fragmentation of the lipid\nmicroparticles into nanoparticles. The reactor allows us to obtain emulsions or\nsuspensions with particle diameters tunable between 20 and 800 nm when\nappropriate surfactants, temperature profiles, and flow rates are applied. The\nfragmentation is comparable to that in a high-pressure homogenizer at ca. 500\nbars or higher, without creating emulsion overheating or cavitation typical for\nthe conventional methods. The flow reactor can be scaled up to industrial\napplications using simple scaling rules."
    },
    {
        "anchor": "Hydrogen Bonds, Hydrophobicity Forces and the Character of the Collapse\n  Transition: We study the thermodynamic behavior of a model protein with 54 amino acids\nthat is designed to form a three-helix bundle in its native state. The model\ncontains three types of amino acids and five to six atoms per amino acid, and\nhas the Ramachandran torsion angles as its only degrees of freedom. The force\nfield is based on hydrogen bonds and effective hydrophobicity forces. We study\nhow the character of the collapse transition depends on the strengths of these\nforces. For a suitable choice of these two parameters, it is found that the\ncollapse transition is first-order-like and coincides with the folding\ntransition. Also shown is that the corresponding one- and two-helix segments\nmake less stable secondary structure than the three-helix sequence.",
        "positive": "Clustering and heterogeneous dynamics in a kinetic Monte-Carlo model of\n  self-propelled hard disks: We introduce a kinetic Monte-Carlo model for self-propelled hard disks to\ncapture with minimal ingredients the interplay between thermal fluctuations,\nexcluded volume and self-propulsion in large assemblies of active particles. We\nanalyze in detail the resulting (density, self-propulsion) nonequilibrium phase\ndiagram over a broad range of parameters. We find that purely repulsive hard\ndisks spontaneously aggregate into fractal clusters as self-propulsion is\nincreased, and rationalize the evolution of the average cluster size by\ndeveloping a kinetic model of reversible aggregation. As density is increased,\nthe nonequilibrium clusters percolate to form a ramified structure reminiscent\nof a physical gel. We show that the addition of a finite amount of noise is\nneeded to trigger a nonequilibrium phase separation, showing that demixing in\nactive Brownian particles results from a delicate balance between noise,\ninterparticle interactions and self-propulsion. We show that self-propulsion\nhas a profound influence on the dynamics of the active fluid. We find that the\ndiffusion constant has a nonmonotonic behaviour as self-propulsion is increased\nat finite density and that activity produces strong deviations from Fickian\ndiffusion that persist over large time scales and length scales, suggesting\nthat systems of active particles generically behave as dynamically\nheterogeneous systems."
    },
    {
        "anchor": "Structure of a liquid crystalline fluid around a macroparticle: Density\n  functional theory study: The structure of a molecular liquid, in both the nematic liquid crystalline\nand isotropic phases, around a cylindrical macroparticle, is studied using\ndensity functional theory. In the nematic phase the structure of the fluid is\nhighly anisotropic with respect to the director, in agreement with results from\nsimulation and phenomenological theories. On going into the isotropic phase the\nstructure becomes rotationally invariant around the macroparticle with an\noriented layer at the surface.",
        "positive": "Statistical Image Analysis of Drying Bovine Serum Albumin Droplets in\n  Phosphate Buffered Saline: A bio-colloidal drying droplet can be used as a pre-diagnostic technique.\nHowever, a successful clinical setting requires a fundamental understanding of\nthe final morphology and the way it is related to the initial state of the\nconstituents present in the droplet. This chapter focuses on the physics\nassociated with different pattern formations in the globular protein, bovine\nserum albumin (BSA) at different phosphate-buffered saline concentrations. The\nstudy reports that the first-order statistics (FOS) and the gray level\nco-occurrence matrix (GLCM) analysis are capable of capturing structural\nchanges of the droplets. While the FOS of the image depends on the individual\npixels, the GLCM summarizes both tonal and structural relationships between the\nneighboring pixels. The horizontal and the vertical orientations of the GLCM\nparameters show a non-significant effect when the pixel displacement is $\\leq$\n1. Interestingly, two local equilibrium-like regions (the rim and the central\nregions) appear when these droplets approach the steady-state. The bimodal\ndistribution confirms that the BSA-BSA interactions are dominant (recessive)\nover the BSA-saline interactions in the rim (central) regions that result in\nthe phase-separated aggregation of the BSA particles in the presence of the\nsalts."
    },
    {
        "anchor": "Theory of viscoelastic adhesion and friction: We present a novel theory of the adhesive contact of linear viscoelastic\nmaterials against rigid substrates moving at constant velocity. Despite the\nnon-conservative behavior of the system, the closure equation of the contact\nproblem can be rigorously formulated in the form of a local energy balance. In\nthe case of adhesiveless contacts, this is equivalent to enforce the\nstationarity of the total energy stored into the viscoelastic material.\nHowever, in the presence of interfacial adhesion, the appearance of\nnon-conservative terms leads to different values of the energy release rates G1\nand G2 at the contact trailing and leading edges, respectively. Specifically,\nthe present theory predicts a non-monotonic trend of G1 and G2 as function of\nthe indenter velocity, as well as a very significant enhancement of hysteretic\nfriction due to the coupling between adhesion and viscoelasticity, compared to\nthe adhesiveless case. Both predictions are in very good agreement with\nexisting experimental data.",
        "positive": "Nano-scale brushes: How to build a smart surface coating: Via computer simulations, we demonstrate how a densely grafted layer of\npolymers, a {\\it brush}, could be turned into an efficient switch through\nchemical modification of some of its end-monomers. In this way, a surface\ncoating with reversibly switchable properties can be constructed. We analyze\nthe fundamental physical principle behind its function, a recently discovered\nsurface instability, and demonstrate that the combination of a high grafting\ndensity, an inflated end-group size and a high degree of monodispersity are\nconditions for an optimal functionality of the switch."
    },
    {
        "anchor": "Entropy driven aggregation of adhesion sites of supported membranes: We study, by means of mean field calculations and Monte Carlo simulations of\na lattice-gas model, the distribution of adhesion sites of a bilayer membrane\nand a supporting flat surface. Our model accounts for the many-body character\nof the attractive interactions between adhesion points induced by the membrane\nthermal fluctuations. We show that while the fluctuation-mediated interactions\nalone are not sufficient to allow the formation of aggregation domains, they\ngreatly reduce the strength of the direct interactions required to facilitate\ncluster formation. Specifically, for adhesion molecules interacting via a short\nrange attractive potential, the strength of the direct interactions required\nfor aggregation is reduced by about a factor of two to below the thermal energy\n$k_BT$.",
        "positive": "Viscoelasticity near the gel-point: a molecular dynamics study: We report on extensive molecular dynamics simulations on systems of soft\nspheres of functionality f, i.e. particles that are capable of bonding\nirreversibly with a maximum of f other particles. These bonds are randomly\ndistributed throughout the system and imposed with probability p. At a critical\nconcentration of bonds, p_c approximately equal to 0.2488 for f=6, a gel is\nformed and the shear viscosity \\eta diverges according to \\eta ~ (p_c-p)^{-s}.\nWe find s is approximately 0.7 in agreement with some experiments and with a\nrecent theoretical prediction based on Rouse dynamics of phantom chains. The\ndiffusion constant decreases as the gel point is approached but does not\ndisplay a well-defined power law."
    },
    {
        "anchor": "Tuning Jammed Frictionless Disk Packings from Isostatic to Hyperstatic: We perform extensive computational studies of two-dimensional static\nbidisperse disk packings using two distinct packing-generation protocols. The\nfirst involves thermally quenching equilibrated liquid configurations to zero\ntemperature over a range of thermal quench rates $r$ and initial packing\nfractions followed by compression and decompression in small steps to reach\npacking fractions $\\phi_J$ at jamming onset. For the second, we seed the system\nwith initial configurations that promote micro- and macrophase-separated\npackings followed by compression and decompression to $\\phi_J$. We find that\namorphous, isostatic packings exist over a finite range of packing fractions\nfrom $\\phi_{\\rm min} \\le \\phi_J \\le \\phi_{\\rm max}$ in the large-system limit,\nwith $\\phi_{\\rm max} \\approx 0.853$. In agreement with previous calculations,\nwe obtain $\\phi_{\\rm min} \\approx 0.84$ for $r > r^*$, where $r^*$ is the rate\nabove which $\\phi_J$ is insensitive to rate. We further compare the structural\nand mechanical properties of isostatic versus hyperstatic packings. The\nstructural characterizations include the contact number, bond orientational\norder, and mixing ratios of the large and small particles. We find that the\nisostatic packings are positionally and compositionally disordered, whereas\nbond-orientational and compositional order increase with contact number for\nhyperstatic packings. In addition, we calculate the static shear modulus and\nnormal mode frequencies of the static packings to understand the extent to\nwhich the mechanical properties of amorphous, isostatic packings are different\nfrom partially ordered packings. We find that the mechanical properties of the\npackings change continuously as the contact number increases from isostatic to\nhyperstatic.",
        "positive": "Adhesive Release via Elasto-Osmotic Stress Driven Surface Instability: Recent studies demonstrated that an elastomer containing hygroscopic\ninclusions absorbs moisture and swell. Here we show that a thin film of such an\nelastomer bonded to a rigid substrate undergoes morphological instability upon\nabsorption of water, the wavelength of which increases linearly with its\nthickness. As the driving force for such a morphological instability arises\nfrom the difference of the chemical potential of water between its source and\nthat in the film, its development is slowed down as the salinity of the water\nincreases. Nonetheless, the wavelength of the fully developed morphology, but\nnot its amplitude, is independent of the salinity. We also demonstrate that if\na domed disk shaped adherent is attached to the hygro-elastomeric film before\nmoisture absorption, the elastic force generated during the morphological\ntransition is able to dislodge it completely without the need of any external\nforce. These patterns, once developed in pure water, is subdued when the\nsalinity of water increases or if it is exposed to dry air. They re-emerge when\nthe film is immersed in water again. Such an active response could be important\nin fouling release when a ship coated with such a hygro-elastomer changes its\nlocation during its long travel through sea, where salinity varies from place\nto place."
    },
    {
        "anchor": "A new setup for giant soap films characterization: Artists, using an empirical knowledge, manage to generate and play with giant\nsoap films and bubbles. Until now, scientific studies of soap films generated\nat a controlled velocity and without any feeding from the top, studied films of\na few square centimeters. The present work aims to present a new setup to\ngenerate and characterize giant soap films (2~m $\\times$ 0.7~m). Our setup is\nenclosed in a humidity-controlled box of 2.2~m high, 1~m long and 0.75~m large.\nSoap films are entrained by a fishing line withdrawn out of a bubbling solution\nat various velocities. We measure the maximum height of the generated soap\nfilms, as well as their lifetime, thanks to an automatic detection. This is\nallowed by light-sensitive resistors collecting the light reflected on the soap\nfilms and ensures robust statistical measurements. In the meantime, thickness\nmeasurements are performed with a UV-VIS-spectrometer, allowing us to map the\nsoap films thickness over time.",
        "positive": "Structural Transitions, Melting, and Intermediate Phases for Stripe and\n  Clump Forming Systems: We numerically examine the properties of a two-dimensional system of\nparticles which have competing long range repulsive and short range attractive\ninteractions as a function of density and temperature. For increasing density,\nthere are well defined transitions between a low density clump phase, an\nintermediate stripe phase, an anticlump phase, and a high density uniform\nphase. To characterize the transitions between these phases we propose several\nmeasures which take into account the different length scales in the system. For\nincreasing temperature, we find an intermediate phase that is liquid-like on\nthe short length scale of interparticle spacing but solid-like on the larger\nlength scale of the clump, stripe, or anticlump pattern. This intermediate\nphase persists over the widest temperature range in the stripe state when the\nlocal particle lattice within an individual stripe melts well below the\ntemperature at which the entire stripe structure breaks down, and is\ncharacterized by intra-stripe diffusion of particles without inter-stripe\ndiffusion. This is followed at higher temperatures by the onset of inter-stripe\ndiffusion in an anisotropic diffusion phase, and then by breakup of the stripe\nstructure. We identify the transitions between these regimes through diffusion,\nspecific heat, and energy fluctuation measurements, and find that within the\nintra-stripe liquid regime, the excess entropy goes into disordering the\nparticle arrangements within the stripe rather than affecting the stripe\nstructure itself. The clump and anticlump phases also show multiple\ntemperature-induced diffusive regimes which are not as pronounced as those of\nthe stripe phase."
    },
    {
        "anchor": "Direct measurement of the intermolecular forces confining a single\n  molecule in an entangled polymer solution: We use optical tweezers to directly measure the intermolecular forces acting\non a single polymer imposed by surrounding entangled polymers (115 kbp DNA, 1\nmg/ml). A tube-like confining field was measured in accord with the key\nassumption of reptation models. A time-dependent harmonic potential opposed\ntransverse displacement, in accord with recent simulation findings. A tube\nradius of 0.8 microns was determined, close to the predicted value (0.5\nmicrons). Three relaxation modes (~0.4, 5 and 30 s) were measured following\ntransverse displacement, consistent with predicted relaxation mechanisms.",
        "positive": "Configurational temperature in active matter. I. Lines of invariant\n  physics in the phase diagram of the Ornstein-Uhlenbeck model: This paper shows that the configurational temperature of liquid-state theory,\n$\\Tc$, defines an energy scale, which can be used for adjusting model\nparameters of active Ornstein-Uhlenbeck particle (AOUP) models in order to\nachieve approximately invariant structure and dynamics upon a density change.\nThe required parameter changes are calculated from the variation of a single\nconfiguration's $\\Tc$ for a uniform scaling of all particle coordinates. The\nresulting equations are justified theoretically for models involving a\npotential-energy function with hidden scale invariance. The validity of the\nprocedure is illustrated by computer simulations of the Kob-Andersen binary\nLennard-Jones AOUP model, demonstrating lines of approximate reduced-unit\ninvariance of the radial distribution function and time-dependent mean-square\ndisplacement."
    },
    {
        "anchor": "Elongational viscosity of weakly entangled polymer melt via\n  coarse-grained molecular dynamics simulation: We investigated the elongational flows of the weakly entangled linear polymer\nmelt using a coarse-grained molecular dynamics simulation. We extended the\nuniform extensional flow (UEF) method developed by Nicholson and Rutledge (D.\nA. Nicholson and G. C. Rutledge, J. Chem. Phys., 145, 244903 (2016)) for\napplication to Langevin dynamics. We succeeded in observing the elongational\nviscosity of the weakly entangled linear polymer melt from the equilibrium\nstate to the steady state using the extended UEF method, whereas the\nconventional rectangular parallelepiped shape technique for extensional flows\nhas failed to do so for over 20 years.",
        "positive": "Diffusiophoretic manipulation of particles in a drop deposited on a\n  hydrogel: We report an experimental study on the manipulation of colloidal particles in\na drop sitting on a hydrogel. The manipulation is achieved by diffusiophoresis,\nwhich describes a directed motion of particles induced by solute gradients. By\nletting the solute concentrations for the drop and the hydrogel be different,\nwe control the motion of particles in a stable suspension, which is otherwise\ndifficult to achieve. We show that diffusiophoresis can cause the particles to\nmove either toward or away from the liquid-air interface depending on the\ndirection of the solute gradient and the surface charge of the particles. We\nmeasure the particle adsorption experimentally and rationalize the results with\na one-dimensional numerical model. We show that diffusiophoretic motion is\nsignificant at the lengthscale of a drop deposited on a hydrogel, which\nsuggests a simple method for the deposition of particles on hydrogels."
    },
    {
        "anchor": "Versatile coating platform for metal oxide nanoparticles: applications\n  to materials and biological science: In this feature article, we provide an overview of our research on\nstatistical copolymers as a coating material for metal oxide nanoparticles and\nsurfaces. These copolymers contain functional groups enabling non-covalent\nbinding to oxide surfaces and poly(ethylene glycol) (PEG) polymers for\ncolloidal stability and stealthiness. The functional groups are organic\nderivatives of phosphorous acid compounds R-H$_2$PO$_3$, also known as\nphosphonic acids that have been screened for their strong affinity to metals\nand their ability to build multidentate binding. Herein we develop a\npolymer-based coating platform that shares features with the techniques of\nself-assembled monolayers (SAM) and Layer-by-Layer (L-b-L) deposition. The\nmilestones of this endeavor are the synthesis of PEG-based copolymers\ncontaining multiple phosphonic acid groups, the implementation of simple\nprotocols combining versatility with high particle production yields and the\nexperimental demonstration of the colloidal stability of the coated particles.\nAs a demonstration, coating studies are conducted on cerium (CeO$_2$), iron\n($\\gamma$-Fe$_2$O$_3$), aluminum (Al$_2$O$_3$) and titanium (TiO$_2$) oxides of\ndifferent sizes and morphologies. We finally discuss applications in the domain\nof nanomaterials and nanomedicine. We evaluate the beneficial effects of\ncoating on redispersible nanopowders, contrast agents for In Vitro/Vivo assays\nand stimuli-responsive particles.",
        "positive": "Jaming and Geometry of Two-Dimensional Foams: We experimentally probe the vicinity of the jamming point J, located at a\ndensity $\\phi$ corresponding to random close packing ($\\phi_{rcp} = 0.842$), in\ntwo dimensional, bidisperse packings of foam bubbles. We vary the density of\nthe foam layer and extract geometrical measures by image analysis. We confirm\nthe predicted scaling of the average contact number Z with $\\phi$ and compare\nthe distribution of local contact numbers to a simple model. We further\nestablish that the distribution of areas $p(A)$ strongly depends on $\\phi$.\nFinally, we find that the distribution of contact forces $p(f)$ systematically\nvaries with density."
    },
    {
        "anchor": "Healing Length and Bubble Formation in DNA: We have recently suggested that the probability for the formation of\nthermally activated DNA bubbles is, to a very good approximation, proportional\nto the number of soft AT pairs over a length L(n) that depend on the size $n$\nof the bubble and on the temperature of the DNA. Here we clarify the physical\ninterpretation of this length by relating it to the (healing) length that is\nrequired for the effect of a base-pair defect to become neligible. This\nprovides a simple criteria to calculate L(n) for bubbles of arbitrary size and\nfor any temperature of the DNA. We verify our findings by exact calculations of\nthe equilibrium statistical properties of the Peyrard-Bishop-Dauxois model. Our\nmethod permits calculations of equilibrium thermal openings with several order\nof magnitude less numerical expense as compared with direct evaluations.",
        "positive": "Liquid drops on a surface: using density functional theory to calculate\n  the binding potential and drop profiles and comparing with results from\n  mesoscopic modelling: The contribution to the free energy for a film of liquid of thickness $h$ on\na solid surface, due to the interactions between the solid-liquid and\nliquid-gas interfaces is given by the binding potential, $g(h)$. The precise\nform of $g(h)$ determines whether or not the liquid wets the surface. Note that\ndifferentiating $g(h)$ gives the Derjaguin or disjoining pressure. We develop a\nmicroscopic density functional theory (DFT) based method for calculating\n$g(h)$, allowing us to relate the form of $g(h)$ to the nature of the molecular\ninteractions in the system. We present results based on using a simple lattice\ngas model, to demonstrate the procedure. In order to describe the static and\ndynamic behaviour of non-uniform liquid films and drops on surfaces, a\nmesoscopic free energy based on $g(h)$ is often used. We calculate such\nequilibrium film height profiles and also directly calculate using DFT the\ncorresponding density profiles for liquid drops on surfaces. Comparing\nquantities such as the contact angle and also the shape of the drops, we find\ngood agreement between the two methods. We also study in detail the effect on\n$g(h)$ of truncating the range of the dispersion forces, both those between the\nfluid molecules and those between the fluid and wall. We find that truncating\ncan have a significant effect on $g(h)$ and the associated wetting behaviour of\nthe fluid."
    },
    {
        "anchor": "Investigation of the stability and charge states of vacancy in clusters\n  Si$_{29}$ and Si$_{38}$: Stability and charge states of vacancy in Si$_{29}$ and Si$_{38}$ clusters\nhave been calculated by non-conventional tight-binding method and molecular\ndynamics. Based on the theoretical calculations, it was shown that the vacancy\nin pure dimerized clusters is unstable, while in hydrogenated Si$_{29}$H$_{24}$\nand Si$_{38}$H$_{30}$ clusters it is stable, but leads to a distortion of its\ncentral part with the transition of symmetry from Td to $C_{3v}$ and a change\nin the forbidden gap. The charges of cluster atoms in the presence of a vacancy\nare distributed so that all silicon atoms acquire a stable negative charge,\nwhich occurs due to the outflow of electrons of the central atom to the\nneighboring spheres.",
        "positive": "Analytic model for the ballistic adsorption of polydisperse mixtures: We study the ballistic adsorption of a polydisperse mixture of spheres onto a\nline. Within a mean-field approximation, the problem can be analytically solved\nby means of a kinetic equation for the gap distribution. In the mean-field\napproach, the adsorbed substrate as approximated as composed by {\\em effective}\nparticles with the {\\em same} size, equal to the average diameter of the\nspheres in the original mixture. The analytic solution in the case of binary\nmixtures agrees quantitatively with direct Monte Carlo simulations of the\nmodel, and qualitatively with previous simulations of a related model in $d=2$."
    },
    {
        "anchor": "Systematic coarse-graining of the dynamics of entangled polymer melts:\n  the road from chemistry to rheology: For optimal processing and design of entangled polymeric materials it is\nimportant to establish a rigorous link between the detailed molecular\ncomposition of the polymer and the viscoelastic properties of the macroscopic\nmelt. We review current and past computer simulation techniques and critically\nassess their ability to provide such a link between chemistry and rheology. We\ndistinguish between two classes of coarse-graining levels, which we term\ncoarse-grained molecular dynamics (CGMD) and coarse-grained stochastic dynamics\n(CGSD). In CGMD the coarse-grained beads are still relatively hard, thus\nautomatically preventing bond crossing. This also implies an upper limit on the\nnumber of atoms that can be lumped together and therefore on the longest chain\nlengths that can be studied. To reach a higher degree of coarse-graining, in\nCGSD many more atoms are lumped together, leading to relatively soft beads. In\nthat case friction and stochastic forces dominate the interactions, and actions\nmust be undertaken to prevent bond crossing. We also review alternative methods\nthat make use of the tube model of polymer dynamics, by obtaining the\nentanglement characteristics through a primitive path analysis and by\nsimulation of a primitive chain network. We finally review super-coarse-grained\nmethods in which an entire polymer is represented by a single particle, and\ncomment on ways to include memory effects and transient forces.",
        "positive": "Free-energy barrier to melting of single-chain polymer crystallite: We report Monte Carlo simulations of the melting of a single-polymer\ncrystallite. We find that, unlike most atomic and molecular crystals, such\ncrystallites can be heated appreciably above their melting temperature before\nthey transform to the disordered \"coil\" state. The surface of the superheated\ncrystallite is found to be disordered. The thickness of the disordered layer\nincreases with superheating. However, the order-disorder transition is not\ngradual but sudden. Free-energy calculations reveal the presence of a large\nfree-energy barrier to melting."
    },
    {
        "anchor": "Morphology of Proliferating Epithelial Cellular Tissue: We investigate morphologies of proliferating cellular tissue using a newly\ndeveloped numerical simulation model for mechanical cell division. The model\nreproduces structures of simple multi-cellular organisms via simple rules for\nselective division and division plane orientation. The model is applied to a\nbimodal mixture of stiff cells with a low growth potential and soft cells with\na high growth potential. In an even mixture, the soft cells develop into a\ntissue matrix and the stiff cells into a dendrite-like network structure. For\nsoft cell inclusion in a stiff cellular matrix, the soft cells develop to a\nfast growing tumour like structure that gradually evacuates the stiff cell\nmatrix. With increasing inter-cell friction, the tumour growth slows down and\nparts of it is driven to self-inflicted cell death.",
        "positive": "Rotational motion of dimers of Janus particles: We theoretically study the motion of a rigid dimer of self-propelling Janus\nparticles. In a simple kinetic approach without hydrodynamic interactions, the\ndimer moves on a helical trajectory and, at the same time, it rotates about its\ncenter of mass. Inclusion of the effects of mutual advection using\nsuperposition approximation does not alter the qualitative features of the\nmotion but merely changes the parameters of the trajectory and the angular\nvelocity."
    },
    {
        "anchor": "A modified Ehlers model for the description of inelastic behavior of\n  porous structures: This paper describes a modification of Ehlers' model for the inelastic\nbehavior of granular media. The modified model can be applied for describing\nthe inelastic behavior of porous media. The key feature is a subtle change of\nthe yield potential, which allows the correct orientation of the\ntriangular-shaped yield surface cross sections depending on the hydrostatic\nstress state. The model is incorporated into a general framework for isotropic\nplasticity. An elastic predictor/corrector algorithm is employed to solve the\nconstitutive equations. The necessary derivatives for a Newton update are also\ngiven in detail. The model is calibrated using stress, and strain data obtained\nfrom finite element simulations of a generic highly porous open-cell\nWheire-Phelan foam.",
        "positive": "The Effect of Particle Strength on the Ballistic Resistance of Shear\n  Thickening Fluids: The response of shear thickening fluids (STFs) under ballistic impact has\nreceived considerable attention due to its field-responsive nature. While\nefforts have primarily focused on the response of traditional ballistic fabrics\nimpregnated with fluids, the response of pure STFs to penetration has received\nlimited attention. In the present study, the ballistic response of pure STFs is\ninvestigated and the effect of fluid density and particle strength on ballistic\nperformance is isolated. The loss of ballistic resistance of STFs at higher\nimpact velocities is governed by particle strength, indicating the range of\nvelocities over which they may provide effective armor solutions."
    },
    {
        "anchor": "Three-Particle Correlations in Simple Liquids: We use video microscopy to follow the phase-space trajectory of a\ntwo-dimensional colloidal model liquid and calculate three-point correlation\nfunctions from the measured particle configurations. Approaching the\nfluid-solid transition by increasing the strength of the pair-interaction\npotential, one observes the gradual formation of a crystal-like local order due\nto triplet correlations, while being still deep inside the fluid phase.\nFurthermore, we show that in a strongly interacting system the Born-Green\nequation can be satisfied only with the full triplet correlation function but\nnot with three-body distribution functions obtained from superposing\npair-correlations (Kirkwood superposition approximation).",
        "positive": "Twist-induced crossover from 2D to 3D turbulence in active nematics: While studies of active nematics in two dimensions have shed light on various\naspects of the flow regimes and topology of active matter, three-dimensional\nproperties of topological defects and chaotic flows remain unexplored. By\nconfining a film of active nematics between two parallel plates, we use\ncontinuum simulations and analytical arguments to demonstrate that the\ncrossover from quasi-2D to 3D chaotic flows is controlled by the morphology of\nthe disclination lines. For small plate separations, the active nematic behaves\nas a quasi-2D material, with straight topological disclination lines spanning\nthe height of the channel and exhibiting effectively 2D active turbulence. Upon\nincreasing channel height, we find a crossover to 3D chaotic flows due to the\ncontortion of disclinations above a critical activity. We further show that\nthese contortions are engendered by twist perturbations producing a sharp\nchange in the curvature of disclinations."
    },
    {
        "anchor": "Lifetime of sessile saliva droplets in the context of SARS-CoV-2: Spreading of respiratory diseases, such as COVID-19, from contaminated\nsurfaces is dependent on the drying time of the deposited droplets containing\nthe virus. The evaporation rate depends on environmental conditions, such as\nambient temperature and relative humidity and physical properties (e.g.,\ndroplet volume, contact angle and composition). The respiratory droplets\ncontain salt (NaCl), protein (mucin), and surfactant\n(dipalmitoylphosphatidylcholine) in addition to water, which are expected to\ninfluence the evaporation in a big way. A diffusion-based theoretical model for\nestimating the drying time is developed which takes into account the dynamic\ncontact angle of saliva droplets laden with salt and insoluble surfactants. The\neffect of the initial volume, contact angle, salinity, surfactant\nconcentration, ambient temperature and relative humidity on the drying time of\ndroplets is investigated.",
        "positive": "Transformation between elastic dipoles, quadrupoles, octupoles and\n  hexadecapoles driven by surfactant self-assembly in nematic emulsion: Emulsions comprising isotropic fluid drops within a nematic host are of\ninterest for applications ranging from biodetection to smart windows, which\nrely on changes of molecular alignment structures around the drops in response\nto chemical, thermal, electric and other stimuli. We show that absorption or\ndesorption of trace amounts of common surfactants can drive continuous\ntransformations of elastic multipoles induced by the droplets within the\nuniformly aligned nematic host. Out-of-equilibrium dynamics of director\nstructures emerge from a controlled self-assembly or desorption of different\nsurfactants at the drop-nematic interfaces, with ensuing forward and reverse\ntransformations between elastic dipoles, quadrupoles, octupoles and\nhexadecapoles. We characterize inter-transformations of droplet-induced surface\nand bulk defects, probe elastic pair interactions and discuss emergent\nprospects for fundamental science and applications of the reconfigurable\nnematic emulsions."
    },
    {
        "anchor": "Optimized Large Hyperuniform Binary Colloidal Suspensions in Two\n  Dimensions: The creation of disordered hyperuniform materials with potentially\nextraordinary optical properties requires a capacity to synthesize large\nsamples that are effectively hyperuniform down to the nanoscale. Motivated by\nthis challenge, we propose a fabrication protocol using binary\nsuperparamagnetic colloidal particles confined in a 2D plane. The strong and\nlong-ranged dipolar interaction induced by a tunable magnetic field is free\nfrom screening effects that attenuates long-ranged electrostatic interactions\nin charged colloidal systems. Specifically, we find a family of optimal size\nratios that makes the two-phase system effectively hyperuniform. We show that\nhyperuniformity is a general consequence of low isothermal compressibilities,\nwhich makes our protocol suitable to systems with other long-ranged soft\ninteractions, dimensionalities and/or polydispersity. Our methodology paves the\nway to synthesize large photonic hyperuniform materials that function in the\nvisible to infrared range and hence may accelerate the discovery of novel\nphotonic materials.",
        "positive": "Scaling in soft spheres: fragility invariance on the repulsive potential\n  softness: We address the question of the dependence of the fragility of glass forming\nsupercooled liquids on the softness of an interacting potential by performing\nnumerical simulation of a binary mixture of soft spheres with different power n\nof the interparticle repulsive potential. We show that the temperature\ndependence of the diffusion coefficients for various $n$ collapses onto a\nuniversal curve, supporting the unexpected view that fragility is not related\nto the hard core repulsion. We also find that the configurational entropy\ncorrelates with the slowing down of the dynamics for all studied n."
    },
    {
        "anchor": "Smooth waves and shocks of finite amplitude in soft materials: Recently developed soft materials exhibit nonlinear wave propagation with\npotential applications for energy trapping, shock mitigation and wave focusing.\nWe address finitely deformed materials subjected to combined transverse and\naxial impacts, and study the resultant nonlinear waves. We determine the\ndependency of the induced motion on the impact, pre-deformation and the\nemployed constitutive models. We analyze the neo-Hookean constitutive model and\nshow it cannot capture shear shocks and tensile-induced shocks, in contrast\nwith experimental results on soft materials. We find that the Gent constitutive\nmodel predicts that compressive impact may not be sufficient to induce a\nquasi-pressure shock---yet it may induce a quasi-shear shock, where tensile\nimpact can trigger quasi-pressure shock ---and may simultaneously trigger a\nquasi-shear shock, in agreement with experimental data. We show that the\ntensile impact must be greater than a calculated threshold value to induce\nshock, and demonstrate that this threshold is lowered by application of\npre-shear.",
        "positive": "Cumulative geometric frustration in physical assemblies: Geometric frustration arises whenever the constituents of a physical assembly\nlocally favor an arrangement that cannot be realized globally. Recently, such\nfrustrated assemblies were shown to exhibit filamentation, size limitation,\nlarge morphological variations and other exotic response properties. While\nthese unique characteristics can be shown to be a direct outcome of the\ngeometric frustration, some geometrically frustrated systems do not exhibit any\nof the above phenomena. In this work we exploit the intrinsic approach to\nprovide a framework for directly addressing the frustration in physical\nassemblies. The framework highlights the role of the compatibility conditions\nassociated with the intrinsic fields describing the physical assembly. We show\nthat the structure of the compatibility conditions determines the behavior of\nsmall assemblies, and in particular predicts their super-extensive energy\ngrowth exponent. We illustrate the use of this framework to several well known\nfrustrated assemblies."
    },
    {
        "anchor": "Interaction network analysis in shear thickening suspensions: Dense, stabilized, frictional particulate suspensions in a viscous liquid\nundergo increasingly strong continuous shear thickening (CST) as the solid\npacking fraction, $\\phi$, increases above a critical volume fraction, and\ndiscontinuous shear thickening (DST) is observed for even higher packing\nfractions. Recent studies have related shear thickening to a transition from\nmostly lubricated to predominantly frictional contacts with the increase in\nstress. The rheology and networks of frictional forces from two and\nthree-dimensional simulations of shear-thickening suspensions are studied.\nThese are analyzed using measures of the topology of the network, including\ntools of persistent homology. We observe that at low stress the frictional\ninteraction networks are predominantly quasi-linear along the compression axis.\nWith an increase in stress, the force networks become more isotropic, forming\nloops in addition to chain-like structures. The topological measures of Betti\nnumbers and total persistence provide a compact means of describing the mean\nproperties of the frictional force networks and provide a key link between\nmacroscopic rheology and the microscopic interactions. A total persistence\nmeasure describing the significance of loops in the force network structure, as\na function of stress and packing fraction, shows behavior similar to that of\nrelative viscosity and displays a scaling law near the jamming fraction for\nboth dimensionalities simulated.",
        "positive": "Dielectric anisotropy in polar solvents under external fields: We investigate dielectric saturation and increment in polar liquids under\nexternal fields. We couple a previously introduced dipolar solvent model to a\nuniform electric field and derive the electrostatic kernel of interacting\ndipoles. This procedure allows an unambiguous definition of the liquid\ndielectric permittivity embodying non-linear dielectric response and\ncorrelation effects.We find that the presence of the external field results in\na dielectric anisotropy characterized by a two-component dielectric\npermittivity tensor. The increase of the electric field amplifies the\npermittivity component parallel to the field direction, i.e. dielectric\nincrement is observed along the field. However, the perpendicular component is\nlowered below the physiological permittivity, indicating dielectric saturation\nperpendicular to the field. By comparison with Molecular Dynamics simulations\nfrom the literature, we show that the mean-field level dielectric response\ntheory underestimates dielectric saturation. The inclusion of dipolar\ncorrelations at the weak-coupling level intensify the mean-field level\ndielectric saturation and improves the agreement with simulation data at weak\nelectric fields. The correlation-corrected theory predicts as well the presence\nof a metastable configuration corresponding to the antiparallel alignment of\ndipoles with the field. This prediction can be verified by solvent-explicit\nsimulations where solvent molecules are expected to be trapped transiently in\nthis metastable state."
    },
    {
        "anchor": "Drying and percolation in spatially correlated porous media: We study how the dynamics of a drying front propagating through a porous\nmedium are affected by small-scale correlations in material properties. For\nthis, we first present drying experiments in micro-fluidic micro-models of\nporous media. Here, the fluid pressures develop more intermittent dynamics as\nlocal correlations are added to the structure of the pore spaces. We also\nconsider this problem numerically, using a model of invasion percolation with\ntrapping, and find that there is a crossover in invasion behaviour associated\nwith the length-scale of the disorder in the system. The critical exponents\nassociated with large enough events are similar to the classic invasion\npercolation problem, whereas the addition of a finite correlation length\nsignificantly affects the exponent values of avalanches and bursts, up to some\ncharacteristic size. This implies that the even a weak local structure can\ninterfere with the universality of invasion percolation phenomena.",
        "positive": "A Microscopic Field Theory for the Universal Shift of Sound Velocity and\n  Dielectric Constant in Low-Temperature Glasses: In low-temperature glasses, the sound velocity changes as the logarithmic\nfunction of temperature below $10$K: $[c(T) - c(T_0)]/c(T_0) =\n\\mathcal{C}\\ln(T/T_0)$. With increasing temperature starting from $T=0$K, the\nsound velocity does not increase monotonically, but reaches a maximum at a few\nKelvin and decreases at higher temperatures. Tunneling-two-level-system (TTLS)\nmodel explained the $\\ln T$ dependence of sound velocity shift. In TTLS model\nthe slope ratio of $\\ln T$ dependence of sound velocity shift between lower\ntemperature increasing regime (resonance regime) and higher temperature\ndecreasing regime (relaxation regime) is $\\mathcal{C}^{\\rm res\n}:\\mathcal{C}^{\\rm rel }=1:-\\frac{1}{2}$. In this paper we develop the generic\ncoupled block model to prove the slope ratio of sound velocity shift between\ntwo regimes is $\\mathcal{C}^{\\rm res }:\\mathcal{C}^{\\rm rel }=1:-1$ rather than\n$1:-\\frac{1}{2}$, which agrees with the majority of the measurements. The\ndielectric constant shift in low-temperature glasses,\n$[\\epsilon_r(T)-\\epsilon_r(T_0)]/\\epsilon_r(T_0)$, has a similar logarithmic\ntemperature dependence below $10$K: $[\\epsilon(T)-\\epsilon(T_0)]/\\epsilon(T_0)\n= \\mathcal{C}\\ln(T/T_0)$. In TTLS model the slope ratio of dielectric constant\nshift between resonance and relaxation regimes is $\\mathcal{C}^{\\rm\nres}:\\mathcal{C}^{\\rm rel}=-1:\\frac{1}{2}$. In this paper we apply the electric\ndipole-dipole interaction, to prove that the slope ratio between two regimes is\n$\\mathcal{C}^{\\rm res}:\\mathcal{C}^{\\rm rel} = -1:1$ rather than\n$-1:\\frac{1}{2}$. Our result agrees with the dielectric constant measurements.\nBy developing a real space renormalization technique for glass non-elastic and\ndielectric susceptibilities, we show that these universal properties\nessentially come from the $1/r^3$ long range interactions, independent of the\nmaterials' microscopic properties."
    },
    {
        "anchor": "Towards the description of water adsorption in slit-like nanochannels\n  with grafted molecular brushes. Density functional theory: We have explored a model for adsorption of water into slit-like nanochannels\nwith two walls chemically modified by grafted polymer layers forming brushes. A\nversion of density functional method is used as theoretical tools. The\nwater-like fluid model adopted from the work of Clark et al. [Mol. Phys., 2006,\n104, 3561] adequately reproduces the bulk vapour-liquid coexistence envelope.\nThe polymer layer consists of chain molecules in the framework of\npearl-necklace model. Each chain molecule is chemically bonded to the pore\nwalls by a single terminating segment. Our principal focus is in the study of\nthe dependence of polymer layer height on grafting density and in the\nmicroscopic structure of the interface between adsorbed fluid and brushes.\nThermal response of these properties upon adsorption is investigated in detail.\nThe results are of importance to understand shrinking and swelling of the\nmolecular brushes in the nanochannels.",
        "positive": "Chaoticity of the Wet Granular Gas: In this work we derive an analytic expression for the Kolmogorov-Sinai\nentropy of dilute wet granular matter, valid for any spatial dimension. The\ngrains are modelled as hard spheres and the influence of the wetting liquid is\ndescribed according to the Capillary Model, in which dissipation is due to the\nhysteretic cohesion force of capillary bridges. The Kolmogorov-Sinai entropy is\nexpanded in a series with respect to density. We find a rapid increase of the\nleading term when liquid is added. This demonstrates the sensitivity of the\ngranular dynamics to humidity, and shows that the liquid significantly\nincreases the chaoticity of the granular gas."
    },
    {
        "anchor": "Volume and porosity thermal regulation in lipid mesophases by coupling\n  mobile ligands to soft membranes: Short DNA linkers are increasingly being exploited for driving specific\nself-assembly of Brownian objects. DNA-functionalised colloids can assemble\ninto ordered or amorphous materials with tailored morphology. Recently, the\nsame approach has been applied to compliant units, including emulsion droplets\nand lipid vesicles. The liquid structure of these substrates introduces new\ndegrees of freedom: the tethers can diffuse and rearrange, radically changing\nthe physics of the interactions. Unlike droplets, vesicles are extremely\ndeformable and DNA-mediated adhesion causes significant shape adjustments. We\ninvestigate experimentally the thermal response of pairs and networks of\nDNA-tethered liposomes and observe two intriguing and possibly useful\ncollective properties: negative thermal expansion and tuneable porosity of the\nliposome networks. A model providing a thorough understanding of this\nunexpected phenomenon is developed, explaining the emergent properties out of\nthe interplay between the temperature-dependent deformability of the vesicles\nand the DNA-mediated adhesive forces.",
        "positive": "Hydrodynamics of Active Defects: from order to chaos to defect ordering: Topological defects play a prominent role in the physics of two-dimensional\nmaterials. When driven out of equilibrium in active nematics, disclinations can\nacquire spontaneous self-propulsion and drive self-sustained flows upon\nproliferation. Here we construct a general hydrodynamic theory for a\ntwo-dimensional active nematic interrupted by a large number of such defects.\nOur equations describe the flows and spatio-temporal defect chaos\ncharacterizing active turbulence, even close to the defect unbinding\ntransition. At high activity, nonequilibrium torques combined with many-body\nscreening cause the active disclinations to spontaneously break rotational\nsymmetry forming a collectively moving defect ordered polar liquid. By\nrecognizing defects as the relevant quasiparticle excitations, we construct a\ncomprehensive phase diagram for two-dimensional active nematics. Using our\nhydrodynamic approach, we additionally show that activity gradients can act\nlike \"electric fields\", driving the sorting of topological charge. This\ndemonstrates the versatility of our continuum model and its relevance for\nquantifying the use of spatially inhomogeneous activity for controlling active\nflows and for the fabrication of active devices with targeted transport\ncapabilities."
    },
    {
        "anchor": "Domain formation in membranes with quenched protein obstacles: Lateral\n  heterogeneity and the connection to universality classes: We show that lateral fluidity in membranes containing quenched protein\nobstacles belongs to the universality class of the two-dimensional random-field\nIsing model. The main feature of this class is the absence of a phase\ntransition: there is no critical point, and macroscopic domain formation does\nnot occur. Instead, there is only one phase. This phase is highly\nheterogeneous, with a structure consisting of micro-domains. The presence of\nquenched protein obstacles thus provides a mechanism to stabilize lipid rafts\nin equilibrium. Crucial for two-dimensional random-field Ising universality is\nthat the obstacles are randomly distributed, and have a preferred affinity to\none of the lipid species. When these conditions are not met, standard Ising or\ndiluted Ising universality apply. In these cases, a critical point does exist,\nmarking the onset toward macroscopic demixing.",
        "positive": "Sufficient minimal model for DNA denaturation: Integration of harmonic\n  scalar elasticity and bond energies: We study DNA denaturation by integrating elasticity -- as described by the\nGaussian network model -- with bond binding energies, distinguishing between\ndifferent base-pair and stacking energies. We use exact calculation, within the\nmodel, of the Helmholtz free-energy of any partial denaturation state, which\nimplies that the entropy of all formed bubbles (\"loops\") is accounted for.\nConsidering base-pair bond removal single events, the bond designated for\nopening is chosen by minimizing the free-energy difference for the process,\nover all remaining base-pair bonds. Despite of its great simplicity, for\nseveral known DNA sequences our results are in accord with available\ntheoretical and experimental studies. Moreover, we report free-energy profiles\nalong the denaturation pathway, which allow to detect stable or meta-stable\npartial denaturation states, composed of \"bubbles\", as local free-energy minima\nseparated by barriers. Our approach allows to study very long DNA strands with\ncommonly available computational power, as we demonstrate for a few random\nsequences in the range 200-800 base-pairs. For the latter we also elucidate the\nself-averaging property of the system. Implications for the well known\nbreathing dynamics of DNA are elucidated."
    },
    {
        "anchor": "Driven Anomalous Diffusion: An example from Polymer Stretching: The way tension propagates along a chain is a key to govern many of anomalous\ndynamics in macromolecular systems. After introducing the weak and the strong\nforce regimes of the tension propagation, we focus on the latter, in which the\ndynamical fluctuations of a segment in a long polymer during its stretching\nprocess is investigated. We show that the response, i.e., average drift, is\nanomalous, which is characterized by the nonlinear memory kernel, and its\nrelation to the fluctuation is nontrivial. These features are discussed on the\nbasis of the generalized Langevin equation, in which the role of the temporal\nchange in spring constant due to the stress hardening is pinpointed. We carried\nout the molecular dynamics simulation, which supports our theory.",
        "positive": "Rosenfeld functional for non-additive hard spheres: The fundamental measure density functional theory for hard spheres is\ngeneralized to binary mixtures of arbitrary positive and moderate negative\nnon-additivity between unlike components. In bulk the theory predicts\nfluid-fluid phase separation into phases with different chemical compositions.\nThe location of the accompanying critical point agrees well with previous\nresults from simulations over a broad range of non-additivities and both for\nsymmetric and highly asymmetric size ratios. Results for partial pair\ncorrelation functions show good agreement with simulation data."
    },
    {
        "anchor": "Non-Gaussian statistics of electrostatic fluctuations of hydration\n  shells: We report the statistics of electric field fluctuations produced by SPC/E\nwater inside a Kihara solute given as a hard-sphere core with a Lennard-Jones\nlayer at its surface. The statistics of electric field fluctuations, obtained\nfrom numerical simulations, are studied as a function of the magnitude of a\npoint dipole placed close to the solute-water interface. The free energy\nsurface as a function of the electric field projected on the dipole direction\nshows a cross-over with the increasing dipole magnitude. While it is a\nsingle-well harmonic function at low dipole values, it becomes a double-well\nsurface at intermediate dipole moment magnitudes, transforming to a single-well\nsurface, with a non-zero minimum position, at still higher dipoles. A broad\nintermediate region where the interfacial waters fluctuate between the two\nminima is characterized by intense field fluctuations, with non-Gaussian\nstatistics and the variance far exceeding the linear-response expectations. The\nexcited state of the surface water is found to be lifted above the ground state\nby the energy required to break approximately two hydrogen bonds. This state is\npulled down in energy by the external electric field of the solute dipole,\nmaking it readily accessible to thermal excitations. The excited state is a\nlocalized surface defect in the hydrogen-bond network creating a stress in the\nnearby network, but otherwise relatively localized in the region closest to the\nsolute dipole.",
        "positive": "The crucial role of adhesion in the transmigration of active droplets\n  through interstitial orifices: Active fluid droplets are a class of soft materials exhibiting autonomous\nmotion sustained by an energy supply. Such systems have been shown to capture\nmotility regimes typical of biological cells and are ideal candidates as\nbuilding-block for the fabrication of soft biomimetic materials of interest in\npharmacology, tissue engineering and lab on chip devices. While their behavior\nis well established in unconstrained environments, much less is known about\ntheir dynamics under strong confinement. Here, we numerically study the physics\nof a droplet of active polar fluid migrating within a microchannel hosting a\nconstriction with adhesive properties, and report evidence of a striking\nvariety of dynamic regimes and morphological features, whose properties\ncrucially depend upon droplet speed and elasticity, degree of confinement\nwithin the constriction and adhesiveness to the pore. Our results suggest that\nnon-uniform adhesion forces are instrumental in enabling the crossing through\nnarrow orifices, in contrast to larger gaps where a careful balance between\nspeed and elasticity is sufficient to guarantee the transition. These\nobservations may be useful for improving the design of artificial\nmicro-swimmers, of interest in material science and pharmaceutics, and\npotentially for cell sorting in microfluidic devices."
    },
    {
        "anchor": "Non-uniform localised distortions in generalised elasticity for liquid\n  crystals: We analyse a recent generalised free-energy for liquid crystals posited by\nVirga and falling in the class of quartic functionals in the spatial gradients\nof the nematic director. We review some known interesting solutions, i. e.,\nuniform heliconical structures, and we find new liquid crystal configurations,\nwhich closely resemble some novel, experimentally detected, structures called\nSkyrmion tubes. These new configurations are characterised by a localised\npattern given by the variation of the conical angle. We study the equilibrium\ndifferential equations and find numerical solutions and analytical\napproximations.",
        "positive": "Optimal strengthening of particle-loaded liquid foams: Foams made of complex fluids such as particle suspensions have a great\npotential for the development of advanced aerated materials. In this paper we\nstudy the rheological behavior of liquid foams loaded with granular\nsuspensions. We focus on the effect of small particles, i.e. particle-to-bubble\nsize ratio smaller than 0.1, and we measure the complex modulus as a function\nof particle size and particle volume fraction. With respect to previous work,\nthe results highlight a new elastic regime characterized by unequaled modulus\nvalues as well as independence of size ratio. A careful investigation of the\nmaterial microstructure reveals that particles organize through the network\nbetween the gas bubbles and form a granular skeleton structure with tightly\npacked particles. The latter is proven to be responsible for the reported new\nelastic regime. Rheological probing performed by strain sweep reveals a\ntwo-step yielding of the material: the first one occurs at small strain and is\nclearly attributed to yielding of the granular skeleton; the second one\ncorresponds to the yielding of the bubble assembly, as observed for\nparticle-free foams. Moreover the elastic modulus measured at small strain is\nquantitatively described by models for solid foams in assuming that the\ngranular skeleton possesses a bulk elastic modulus of order 100 kPa. Additional\nrheology experiments performed on the bulk granular material indicate that this\nsurprisingly high value can be understood as soon as the magnitude of the\nconfinement pressure exerted by foam bubbles on packed grains is considered."
    },
    {
        "anchor": "Are the contemporary financial fluctuations sooner converging to normal?: Based on the tick-by-tick price changes of the companies from the U.S. and\nfrom the German stock markets over the period 1998-99 we reanalyse several\ncharacteristics established by the Boston Group for the U.S. market in the\nperiod 1994-95, which serves to verify their space and time-translational\ninvariance. By increasing the time scales we find a significantly more\naccelerated crossover from the power-law (alpha approximately 3) asymptotic\nbehaviour of the distribution of returns towards a Gaussian, both for the U.S.\nas well as for the German stock markets. In the latter case the crossover is\neven faster. Consistently, the corresponding autocorrelation functions of\nreturns and of the time averaged volatility also indicate a faster loss of\nmemory with increasing time. This route towards efficiency may reflect a\nsystematic increase of the information processing when going from past to\npresent.",
        "positive": "Controlled Propagation and Jamming of a Delamination Front: We study the birth and propagation of a delamination front in the peeling of\na soft, weakly adhesive layer. In a controlled-displacement setting, the layer\npartially detaches via a subcritical instability and the motion continues until\narrested, by jamming of the two lobes. Using numerical solutions and scaling\nanalysis, we quantitatively describe the equilibrium shapes and obtain\nconstitutive sensitivities of jamming process to material and interface\nproperties. We conclude with a way to delay or avoid jamming altogether by\ntunable interface properties."
    },
    {
        "anchor": "Scaling properties of soft matter in equilibrium and under stationary\n  flow: A brief review is presented of the scaling of complex fluids, polymers and\npolyelectrolytes in solution and in confined geometry, in thermodynamical,\nstructural and rheology properties using equilibrium and nonequilibrium\ndissipative particle dynamics simulations. All simulations were carried out on\nhigh performance computational facilities using parallelized algorithms, solved\non computers using both central and graphical processing units. The scaling\napproach is shown to be a unifying axis around which general trends and basic\nknowledge can be gained, illustrated through a series of case studies.",
        "positive": "Screening-Limited Response of NanoBiosensors: Despite tremendous potential of highly sensitive electronic detection of\nbio-molecules by nanoscale biosensors for genomics and proteomic applications,\nmany aspects of experimentally observed sensor response (S) are unexplained\nwithin consistent theoretical frameworks of kinetic response or electrical\nscreening. In this paper, we combine analytic solutions of Poisson-Boltzmann\nand reaction-diffusion equations to show that the electrical response of\nnanobiosensor varies logarithmically with the concentration of target\nmolecules, time, the salt concentration, and inversely with the fractal\ndimension of sensor surface. Our analysis provides a coherent theoretical\ninterpretation of wide variety of puzzling experimental data that have so far\ndefied intuitive explanation."
    },
    {
        "anchor": "In-drop capillary spooling of spider capture thread inspires highly\n  extensible fibres: Spiders' webs and gossamer threads are often paraded as paradigms for\nlightweight structures and outstanding polymers. Probably the most intriguing\nof all spider silks is the araneid capture thread, covered with tiny\nglycoprotein glue droplets. Even if compressed, this thread remains\nsurprisingly taut, a property shared with pure liquid films, allowing both\nthread and web to be in a constant state of tension. Vollrath and Edmonds\nproposed that the glue droplets would act as small windlasses and be\nresponsible for the tension, but other explanations have also been suggested,\ninvolving for example the macromolecular properties of the flagelliform silk\ncore filaments. Here we show that the nanolitre glue droplets of the capture\nthread indeed induce buckling and coiling of the core filaments: microscopic\nin-vivo observations reveal that the slack fibre is spooled into and within the\ndroplets. We model windlass activation as a structural phase transition, and\nshow that fibre spooling essentially results from the interplay between\nelasticity and capillarity. This is demonstrated by reproducing artificially\nthe mechanism on a synthetic polyurethane thread/silicone oil droplet system.\nFibre size is the key in natural and artificial setups which both require\nmicrometer-sized fibres to function. The spools and coils inside the drops are\nfurther shown to directly affect the mechanical response of the thread,\nevidencing the central role played by geometry in spider silk mechanics. Beside\nshedding light on araneid capture thread functionality, we argue that the\nproperties of this biological system provide novel insights for bioinspired\nsynthetic actuators.",
        "positive": "Rheology and Shear Band Suppression in Particle and Chain Mixtures: Using numerical simulations, we consider an amorphous particle mixture which\nexhibits shear banding, and find that the addition of even a small fraction of\nchains strongly enhances the material strength, creating pronounced overshoot\nfeatures in the stress-strain curves. The strengthening occurs in the case\nwhere the chains are initially perpendicular to the shear direction, leading to\na suppression of the shear band. For large strain, the chains migrate to the\nregion where a shear band forms, resulting in a stress drop. The alignment of\nthe chains by the shear bands results in a Bauschinger-like effect for\nsubsequent reversed shear. Many of these features are captured in a simple\nmodel of a single chain being pulled through a viscous material. Our results\nare also useful for providing insights into methods of controlling and\nstrengthening granular materials against failure."
    },
    {
        "anchor": "Calcium Rubidium Nitrate: Mode-Coupling $\u03b2$ Scaling without\n  Factorization: The fast dynamics of viscous calcium rubidium nitrate is investigated by\ndepolarized light scattering, neutron scattering and dielectric loss. Fast\n$\\beta$ relaxation evolves as in calcium potassium nitrate. The dynamic\nsusceptibilities can be described by the asymptotic scaling law of\nmode-coupling theory with a shape parameter $\\lambda = 0.79$; the temperature\ndependence of the amplitudes extrapolates to $T_c\\simeq 378$ K. However, the\nfrequencies of the minima of the three different spectroscopies never coincide,\nin conflict with the factorization prediction, indicating that the true\nasymptotic regime is unreachable.",
        "positive": "Ground-state properties of hard core bosons in one-dimensional harmonic\n  traps: The one-particle density matrices for hard core bosons in a one-dimensional\nharmonic trap are computed numerically for systems with up to 160 bosons.\nDiagonalization of the density matrix shows that the many-body ground state is\nnot Bose-Einstein condensed. The ground state occupation, the amplitude of the\nlowest natural orbital, and the zero momentum peak height scale as powers of\nthe particle number, and the corresponding exponents are related to each other.\nClose to its diagonal, the density matrix for hard core bosons is similar to\nthe one of noninteracting fermions."
    },
    {
        "anchor": "Slow dynamics under gravity: a nonlinear diffusion model: We present an analytical and numerical study of a nonlinear diffusion model\nwhich describes density relaxation of loosely packed particles under gravity\nand weak random (thermal) vibration, and compare the results with Monte Carlo\nsimulations of a lattice gas under gravity. The dynamical equation can be\nthought of as a local density functional theory for a class of lattice gases\nused to model slow relaxation of glassy and granular materials. The theory\npredicts a jamming transition line between a low density fluid phase and a high\ndensity glassy regime, characterized by diverging relaxation time and\nlogarithmic or power-law compaction according to the specific form of the\ndiffusion coefficient. In particular, we show that the model exhibits history\ndependent properties, such as quasi reversible-irreversible cycle and memory\neffects -- as observed in recent experiments, and dynamical heterogeneities.",
        "positive": "Anomalous vibrational properties in the continuum limit of glasses: The low-temperature thermal properties of glasses are anomalous with respect\nto those of crystals. These thermal anomalies indicate that the low-frequency\nvibrational properties of glasses differ from those of crystals. Recent studies\nrevealed that, in the simplest model of glasses, i.e., the harmonic potential\nsystem, phonon modes coexist with soft localized modes in the low-frequency\n(continuum) limit. However, the nature of low-frequency vibrational modes of\nmore realistic models is still controversial. In the present work, we study the\nLennard-Jones (LJ) system using large-scale molecular-dynamics (MD) simulation\nand establish that the vibrational property of the LJ glass converges to\ncoexistence of the phonon modes and the soft localized modes in the continuum\nlimit as in the case of the harmonic potential system. Importantly, we find\nthat the low-frequency vibrations are rather sensitive to the numerical scheme\nof potential truncation which is usually implemented in the MD simulation, and\nthis is the reason why contradictory arguments have been reported by previous\nworks. We also discuss the physical origin of this sensitiveness by means of a\nlinear stability analysis."
    },
    {
        "anchor": "Gaussian excitations model for glass-former dynamics and thermodynamics: We describe a model for the thermodynamics and dynamics of glass-forming\nliquids in terms of excitations from an ideal glass state to a Gaussian\nmanifold of configurationally excited states. The quantitative fit of this\nthree parameter model to the experimental data on excess entropy and heat\ncapacity shows that ``fragile'' behavior, indicated by a sharply rising excess\nheat capacity as the glass transition is approached from above, occurs in\nanticipation of a first-order transition -- usually hidden below the glass\ntransition -- to a ``strong'' liquid state of low excess entropy. The dynamic\nmodel relates relaxation to a hierarchical sequence of excitation events each\ninvolving the probability of accumulating sufficient kinetic energy on a\nseparate excitable unit. Super-Arrhenius behavior of the relaxation rates, and\nthe known correlation of kinetic with thermodynamic fragility, both follow from\nthe way the rugged landscape induces fluctuations in the partitioning of energy\nbetween vibrational and configurational manifolds. A relation is derived in\nwhich the configurational heat capacity, rather than the configurational\nentropy of the Adam Gibbs equation, controls the temperature dependence of the\nrelaxation times, and this gives a comparable account of the experimental\nobservations.",
        "positive": "Optimal Actuation of Flagellar Magnetic Micro-Swimmers: We present an automated procedure for the design of optimal actuation for\nflagellar magnetic microswimmers based on numerical optimization. Using this\nmethod, a new magnetic actuation method is provided which allows these devices\nto swim significantly faster compared to the usual sinusoidal actuation. This\nleads to a novel swimming strategy which makes the swimmer perform a 3D\nfigure-8 trajectory. This shows that a faster propulsion is obtained when the\nswimmer is allowed to go out-of-plane. This approach is experimentally\nvalidated on a scaled-up flexible swimmer."
    },
    {
        "anchor": "Relaxation dynamics in fluids of platelike colloidal particles: The relaxation dynamics of a model fluid of platelike colloidal particles is\ninvestigated by means of a phenomenological dynamic density functional theory.\nThe model fluid approximates the particles within the Zwanzig model of\nrestricted orientations. The driving force for time-dependence is expressed\ncompletely by gradients of the local chemical potential which in turn is\nderived from a density functional -- hydrodynamic interactions are not taken\ninto account. These approximations are expected to lead to qualitatively\nreliable results for low densities as those within the isotropic-nematic\ntwo-phase region. The formalism is applied to model an initially spatially\nhomogeneous stable or metastable isotropic fluid which is perturbed by\nswitching a two-dimensional array of Gaussian laser beams. Switching on the\nlaser beams leads to an accumulation of colloidal particles in the beam\ncenters. If the initial chemical potential and the laser power are large enough\na preferred orientation of particles occurs breaking the symmetry of the laser\npotential. After switching off the laser beams again the system can follow\ndifferent relaxation paths: It either relaxes back to the homogeneous isotropic\nstate or it forms an approximately elliptical high-density core which is\nelongated perpendicular to the dominating orientation in order to minimize the\nsurface free energy. For large supersaturations of the initial isotropic fluid\nthe high-density cores of neighboring laser beams of the two-dimensional array\nmerge into complex superstructures.",
        "positive": "Sub-wavelength Lithography of Complex 2D and 3D Nanostructures without\n  Dyes: One-photon or two photon absorption by dye molecules in photopolymers enable\ndirect 2D & 3D lithography of micro/nano structures with high spatial\nresolution and can be used effectively in fabricating artificially structured\nnanomaterials. However, the major bottleneck in unleashing the potential of\nthis useful technique is the indispensable usage of dyes that are extremely\nexpensive, highly toxic and usually insoluble in commercially available\nphotopolymers. Here we report a simple, inexpensive and one-step technique for\ndirect-writing of micro/nanostructures, with sub-wavelength resolution at\nextremely high speeds without using any one photon or two photon absorbing dye.\nWe incorporated large amount (20 weight %) of inexpensive photoinitiator into\nthe photopolymer and utilized its two-photon absorbing property for\nsub-wavelength patterning. Complex 2D and 3D patterns were fabricated with\nsub-micron resolution, in commercially available liquid photopolymer to show\nthe impact/versatility of this technique."
    },
    {
        "anchor": "On elliptical soft colloids in smectic-C films: We investigate theoretically the elliptical shapes of soft colloids in freely\nstanding smectic C films, that have been reported recently. The colloids favour\nparallel alignment of the liquid crystal molecules at their surfaces and, for\nsufficiently strong anchoring, will generate a pair of defects at the poles of\nthe colloidal particles. The elastic free energy of the liquid crystal matrix\nwill, in turn, affect the shape of the colloids. In this study we will focus on\nelliptical soft colloids and determine how their equilibrium shapes depend on\nthe elastic constants of the liquid crystal, the anchoring strength, the\nsurface tension and the size of the colloids. A shape diagram is obtained\nanalytically, by minimizing the Frank elastic free energy, in the limit of\nsmall eccentricities. The analytical results are verified, and generalized to\narbitrary eccentricities, by numerical minimization of an appropriate Landau\nfree energy. The latter is required for an adequate description of the\ntopological defects when the liquid crystal correlation length is comparable to\nthe size of the colloidal particles.",
        "positive": "Statistical mechanics of DNA-nanotube adsorption: Attraction between the polycyclic aromatic surface elements of carbon\nnanotubes (CNT) and the aromatic nucleotides of deoxyribonucleic acid (DNA)\nleads to reversible adsorption (physisorption) between the two, a phenomenon\nrelated to hybridization. We propose a Hamiltonian formulation for the zipper\nmodel that accounts for the DNA-CNT interactions and allows for the processing\nof experimental data, which has awaited an available theory for a decade."
    },
    {
        "anchor": "Conching chocolate: A prototypical transition from frictionally jammed\n  solid to flowable suspension with maximal solid content: The mixing of a powder of 10-50{\\mu}m primary particles into a liquid to form\na dispersion with the highest possible solid content is a common industrial\noperation. Building on recent advances in the rheology of such 'granular\ndispersions', we study a paradigmatic example of such powder incorporation: the\nconching of chocolate, in which a homogeneous, flowing suspension is prepared\nfrom an inhomogeneous mixture of particulates, triglyceride oil and\ndispersants. Studying the rheology of a simplified formulation, we find that\nthe input of mechanical energy and staged addition of surfactants combine to\neffect a considerable shift in the jamming volume fraction of the system, thus\nincreasing the maximum flowable solid content. We discuss the possible\nmicroscopic origins of this shift, and suggest that chocolate conching\nexemplifies a ubiquitous class of powder-liquid mixing.",
        "positive": "Active control of transport through nanopores: Passive particle transport through narrow channels is well studied, while for\nactive particle systems, it is not well understood. Here, we demonstrate the\nactive control of the transport through a nanopore via mean-field analysis and\nmolecular dynamics simulations. We prove that the active force enhances the\ntransport efficiency with an effective diffusion coefficient $D_{eff} = D_t (1\n+ Pe^2/6)$, where $D_t$ is the translational diffusion coefficient, and $Pe$ is\nthe P\\'{e}clet number that determines the strength of the active force. For the\nnumber of particles inside the channel, it experiences subdiffusion at short\ntimes and then turns to normal at longer times. Finally, we extend our research\nfor several sinusoidal shapes of the channel surface. More particles are\ntrapped in the channel if the roughness of the channel surface is increased,\nresulting in fewer particles are transported from one side of the channel to\nthe other."
    },
    {
        "anchor": "Instabilities and Solitons in Minimal Strips: We show that highly twisted minimal strips can undergo a non-singular\ntransition, unlike the singular transitions seen in the M\\\"obius strip and the\ncatenoid. If the strip is non-orientable this transition is topologically\nfrustrated, and the resulting surface contains a helical defect. Through a\ncontrolled analytic approximation the system can be mapped onto a scalar\n$\\phi^4$ theory on a non-orientable line bundle over the circle, where the\ndefect becomes a topologically protected kink soliton or domain wall, thus\nestablishing their existence in minimal surfaces. Experimental studies of soap\nfilms confirm these results and demonstrate how the position of the defect can\nbe controlled through boundary deformation.",
        "positive": "Modelling of active contraction pulses in epithelial cells using the\n  vertex model: Several models have been proposed to describe the dynamics of epithelial\ntissues undergoing morphogenetic changes driven by apical constriction pulses,\nwhich differ in where the constriction is applied, either at the perimeter or\nmedial regions. To help discriminate between these models, using the vertex\nmodel for epithelial dynamics, we analysed the impact of where the constriction\nis applied on the final geometry of the active cell that is reducing its apical\nsize. We find that medial activity, characterised by a reduction in the\nreference area in the vertex model, induces symmetry breaking and generates\nanisotropic cell shapes, while isotropic cell shapes and larger contractions\noccur when the reference perimeter in the model is reduced. When plasticity is\nincluded, sufficiently slow processes of medial contractile activity, compared\nwith typical apical constriction pulses, can also achieve significant cell\ncontraction. Finally, we apply the model to describe the active apical\ncontractile pulses observed during cellular mitotic events within the\nepithelial enveloping cell layer in the developing annual killifish\nAustrolebias nigripinnis, being able to quantitatively describe the temporal\nevolution of cell shape changes when perimeter activity and area plasticity are\nincluded. A global fit of all parameters of the vertex model is provided."
    },
    {
        "anchor": "Lagrange Instability of Geodesics in Curved Double Twisted Liquid\n  Crystals: It is shown that curved and flat helical double twisted liquid crystal (DTLC)\nin blue phase, can be unstable (stable) depending of the sign, negative\n(positive) of sectional curvature, depending on the pitch of the helix of the\nnematic crystal. In both cases Cartan torsion is presented. It is also shown\nthat the instability or stability depends on the value of the pitch of the\nhelix in nematic crystals. Frank energy stability A similar result using the\nmethod of Frank energy stability in the twist of cholesteric liquid crystal was\ngiven by Kiselev and Sluckin [PRE 71(2005)], where the free twist number\ndetermines the equilibrium value of the cholesteric liquid crystals (CLC) pitch\nof the helix. As a final example we solve the geodesic equations in twisted\nnematics with variable pitch helix and non-constant torsion. This\nnon-Riemannian geometrical approach, also seems to unify two recent analysis of\ncylindrical columns given by Santangelo et al [PRL 99,(2007)] and the curved\ncrystal endowed with torsion, given by Vitelli et al [Proc Nat Acad Sci\n(2006)]. Stability of toroidal curved surfaces were also previously considered\nby Bowick et al [PRE 69,(2004)], as an example of curvature-induced defect.\nInvestigation of the Lagrangean instability may be useful in the investigation\nof HIV viruses and proteins.",
        "positive": "No unjamming transition in a marginal vertex model of biological tissue: Vertex models are a popular approach to modeling the mechanical and dynamical\nproperties of dense biological tissues, describing the tissue as a network of\nconnected polygons representing the cells. Recently a class of two-dimensional\nvertex models was shown to exhibit a disordered rigidity transition controlled\nby the preferred cellular geometry, echoing experimental findings. An\nattractive variant of these models uses a Voronoi tessellation to describe the\ncells and endows them with a non-equilibrium model of cellular motility,\nleading to rich, glassy behavior. This glassy behavior was suggested to be\ninextricably linked to an underlying jamming transition. We test this\nconjecture, exploring the low-effective-temperature limit of the Voronoi model\nby studying cell trajectories from detailed dynamical simulations in\ncombination with rigidity measurements of energy-minimized disordered cell\nconfigurations. We find that the zero-temperature limit of this model has no\nunjamming transition."
    },
    {
        "anchor": "Topological instabilities of spherical vesicles: Within the framework of the Helfrich elastic theory of membranes and of\ndifferential geometry we study the possible instabilities of spherical vesicles\ntowards double bubbles. We find that not only temperature, but also magnetic\nfields can induce topological transformations between spherical vesicles and\ndouble bubbles and provide a phase diagram for the equilibrium shapes.",
        "positive": "Oscillatory motion of a droplet in an active poroelastic two-phase model: We investigate flow-driven amoeboid motility as exhibited by microplasmodia\nof Physarum polycephalum. A poroelastic two-phase model with rigid boundaries\nis extended to the case of free boundaries and substrate friction. The\ncytoskeleton is modeled as an active viscoelastic solid permeated by a fluid\nphase describing the cytosol. A feedback loop between a chemical regulator,\nactive mechanical deformations, and induced flows gives rise to oscillatory and\nirregular motion accompanied by spatio-temporal contraction patterns. We cover\nextended parameter regimes of active tension and substrate friction by\nnumerical simulations in one spatial dimension and reproduce experimentally\nobserved oscillation periods and amplitudes. In line with experiments, the\nmodel predicts alternating forward and backward ectoplasmatic flow at the\nboundaries with reversed flow in the center. However, for all cases of periodic\nand irregular motion, we observe practically no net motion. A simple\ntheoretical argument shows that directed motion is not possible with a\nspatially independent substrate friction."
    },
    {
        "anchor": "Mesoscale modelling of polymer aggregate digestion: We use mesoscale simulations to gain insight into the digestion of\nbiopolymers by studying the break-up dynamics of polymer aggregates (boluses)\nbound by physical cross-links. We investigate aggregate evolution, establishing\nthat the linking bead fraction and the interaction energy are the main\nparameters controlling stability with respect to diffusion. We show\n$\\textit{via}$ a simplified model that chemical breakdown of the constituent\nmolecules causes aggregates that would otherwise be stable to disperse. We\nfurther investigate breakdown of biopolymer aggregates in the presence of fluid\nflow. Shear flow in the absence of chemical breakdown induces three different\nregimes depending on the flow Weissenberg number ($Wi$). i) At $Wi \\ll 1$,\nshear flow has a negligible effect on the aggregates. ii) At $Wi \\sim 1$, the\naggregates behave approximately as solid bodies and move and rotate with the\nflow. iii) At $Wi \\gg 1$, the energy input due to shear overcomes the\nattractive cross-linking interactions and the boluses are broken up. Finally,\nwe study bolus evolution under the combined action of shear flow and chemical\nbreakdown, demonstrating a synergistic effect between the two at high reaction\nrates.",
        "positive": "Capillary Adhesion at the Nanometer Scale: Molecular dynamics simulations are used to study the capillary adhesion from\na nonvolatile liquid meniscus between a spherical tip and a flat substrate. The\natomic structure of the tip, the tip radius, the contact angles of the liquid\non the two surfaces, and the volume of the liquid bridge are varied. The\ncapillary force between the tip and substrate is calculated as a function of\ntheir separation h. The force agrees with continuum predictions for h down to ~\n5 to 10nm. At smaller h, the force tends to be less attractive than predicted\nand has strong oscillations. This oscillatory component of the capillary force\nis completely missed in the continuum theory, which only includes contributions\nfrom the surface tension around the circumference of the meniscus and the\npressure difference over the cross section of the meniscus. The oscillation is\nfound to be due to molecular layering of the liquid confined in the narrow gap\nbetween the tip and substrate. This effect is most pronounced for large tip\nradii and/or smooth surfaces. The other two components considered by the\ncontinuum theory are also identified. The surface tension term, as well as the\nmeniscus shape, is accurately described by the continuum prediction for h down\nto ~ 1nm, but the capillary pressure term is always more positive than the\ncorresponding continuum result. This shift in the capillary pressure reduces\nthe average adhesion by a factor as large as 2 from its continuum value and is\nfound to be due to an anisotropy in the pressure tensor. The cross-sectional\ncomponent is consistent with the capillary pressure predicted by the continuum\ntheory (i.e., the Young-Laplace equation), but the normal pressure that\ndetermines the capillary force is always more positive than the continuum\ncounterpart."
    },
    {
        "anchor": "Structural investigation of the liquid crystalline phases of three\n  homologues from the series of 4-pentylphenyl-4'-n-alkyloxythiobenzoates (n =\n  9, 10, 11): Polarizing optical microscopy and differential scanning calorimetry are used\nto determine the phase sequence of three liquid crystalline\n4-pentylphenyl-4'-n-alkyloxythiobenzoates with n = 9, 10, 11. The X-ray\ndiffraction method is applied for structural characterization of the liquid\ncrystalline phases. The smectic layer spacing, tilt angle, average distance\nbetween the long axes of molecules and correlation length of the short-range\norder are determined as a function of temperature. For the crystal-like smectic\nphases with hexagonal or herring-bone packing, the unit cell parameters are\nobtained. The presence of the tilted hexagonal phase for n = 10, 11 and tilted\nherring-bone phase for n = 9, 10 is indicated, although the direction of the\ntilt cannot be determined.",
        "positive": "Phase equilibria and interfacial properties of two-dimensional Yukawa\n  fluids: Molecular dynamics simulations of two-dimensional soft Yukawa fluids are\nperformed to analyze the effect that the range of interaction has on coexisting\ndensities and line tension. The attractive one-component fluid and equimolar\nmixtures containing positive and negative particles are studied at different\ntemperatures to locate the region where the vapor-solid and vapor-liquid phases\nare stable. When the range of interaction decreases, the critical temperature\nof the attractive one-component systems decreases. However, for the charged\nmixtures it increases, and this opposite behaviour is understood in terms of\nthe repulsive interactions which are dominant for these systems. The stable\nphase diagram of two-dimensional fluids is defined for smaller values of the\ndecay parameter \\lambda\\ than that of fluids in three dimensions. The\ntwo-dimensional attractive one-component fluid has stable liquid-vapor phase\ndiagram for values of \\lambda<3, in contrast to the three-dimensional case,\nwhere stability has been observed even for values of \\lambda<15. The same trend\nis observed in equimolar mixtures of particles carrying opposite charges."
    },
    {
        "anchor": "Active Solids Model: Rigid Body Motion and Shape-changing Mechanisms: Active solids such as cell collectives, colloidal clusters, and active\nmetamaterials exhibit diverse collective phenomena, ranging from rigid body\nmotion to shape-changing mechanisms. The nonlinear dynamics of such active\nmaterials remains however poorly understood when they host zero-energy\ndeformation modes and when noise is present. Here, we show that stress\npropagation in a model of active solids induces the spontaneous actuation of\nmultiple soft floppy modes, even without exciting vibrational modes. By\nintroducing an adiabatic approximation, we map the dynamics onto an effective\nLandau free energy, predicting mode selection and the onset of collective\ndynamics. These results open new ways to study and design living and robotic\nmaterials with multiple modes of locomotion and shape-change.",
        "positive": "Nonlinear optical refraction of the dye-doped E7 thermotropic liquid\n  crystal at the nematic-isotropic phase transition: It is known that the doping of liquid crystal with dyes usually changes the\nphysical properties of the host, like the transition temperatures and the\noptical absorption among others. In this work we report a study of the\nnonlinear optical refraction of a dye doped sample of the E7 thermotropic\nliquid crystal by the Z-scan technique. It was found that the nonlinear\nrefraction of the sample is higher than the undoped one, diverging at the\nclearing point. Close to the N-I transition, the nonlinear birefringence is\ncharacterized by a critical exponent that seams to confirm the tricritical\nhypothesis of the nature of the N-I phase transition, being independent of the\ndoping."
    },
    {
        "anchor": "Surface Phase Transition in Anomalous Fluid in Nanoconfinement: We explore by molecular dynamic simulations the thermodynamical behavior of\nan anomalous fluid confined inside rigid and flexible nanopores. The fluid is\nmodeled by a two length scale potential. In the bulk this system exhibits the\ndensity and diffusion anomalous behavior observed in liquid water. We show that\nthe anomalous fluid confined inside rigid and flexible nanopores forms layers.\nAs the volume of the nanopore is decreased the rigid surface exhibits three\nconsecutive first order phase transitions associated with the change in the\nnumber of layers. These phase transitions are not present for flexible\nconfinement. Our results indicate that the nature of confinement is relevant\nfor the properties of the confined liquid what suggests that confinement in\ncarbon nanotubes should be quite different from confinement in biological\nchannels.",
        "positive": "Slow Relaxation, Spatial Mobility Gradients and Vitrification in\n  Confined Films: Two decades of experimental research indicates that spatial confinement of\nglass-forming molecular and polymeric liquids results in major changes of their\nslow dynamics beginning at large confinement distances. A fundamental\nunderstanding remains elusive given the generic complexity of activated\nrelaxation in supercooled liquids and the major complications of geometric\nconfinement, interfacial effects and spatial inhomogeneity. We construct a\npredictive, quantitative, force-level theory of relaxation in free-standing\nfilms for the central question of the nature of the spatial mobility gradient.\nThe key new idea is that vapor interfaces speed up barrier hopping in two\ndistinct, but coupled, ways by reducing near surface local caging constraints\nand spatially long range collective elastic distortion. Effective vitrification\ntemperatures, dynamic length scales, and mobile layer thicknesses naturally\nfollow. Our results provide a unified basis for central observations of dynamic\nand pseudo-thermodynamic measurements."
    },
    {
        "anchor": "A comparative study on bulk and nanoconfined water by time-resolved\n  optical Kerr effect spectroscopy: The low frequency vibrational spectra of hydrated porous silica are\nspecifically sensitive to the hydrogen bond interactions and provides a wealth\nof information on the structural and dynamical properties of the water\ncontained in the pores of the matrix. We investigate systematically this\nspectral region of Vycor porous silica (pore size about 4 nm) for a series of\nsamples at different levels of hydration, from the dry matrix to completely\nfilled pores. The spectra are obtained as the Fourier transforms of\ntime-resolved heterodyne detected optical Kerr effect (HD- OKE) measurements.\nThe comparison of these spectra with that of bulk water allows us to extract\nand analyze separately the spectral contributions of the first and second\nhydration layers, as well as that of bulk-like inner water. We conclude that\nthe extra water entering the pores above 10 % water/silica weight ratio behaves\nvery similarly to bulk water. At lower levels of hydration, corresponding to\ntwo complete superficial water layers or less, the H-bond bending and\nstretching bands, characteristic of the tetrahedral coordination of water in\nthe bulk phase, progressively disappear: clearly in these conditions the H-bond\nconnectivity is very different from that of liquid water. A similar behavior is\nobserved for the structural relaxation times, measured from the decay of the\ntime-dependent HD-OKE signal. The value for the inner water is very similar to\nthat of the bulk liquid; that of the first two water layers is definitely\nlonger by about a factor 4. These findings should be carefully taken into\naccount when employing pore confinement to extend towards lower temperatures\nthe accessible temperature range of supercooled water.",
        "positive": "Density functional theory for the freezing of soft-core fluids: We present a simple density functional theory for the solid phases of systems\nof particles interacting via soft-core potentials. In particular, we apply the\ntheory to particles interacting via repulsive point Yukawa and Gaussian pair\npotentials. We find qualitative agreement with the established phase diagrams\nfor these systems. The theory is able to account for the bcc-fcc solid\ntransitions of both systems and the re-entrant melting that the Gaussian system\nexhibits."
    },
    {
        "anchor": "Mechanical fluctuations suppress the threshold of soft-glassy solids :\n  the secular drift scenario: We propose a dynamical mechanism leading to the fluidization of soft-glassy\namorphous mate-rial driven below the yield-stress by external mechanical\nfluctuations. The model is based on the combination of memory effect and\nnon-linearity, leading to an accumulation of tiny effects over a long-term. We\ntest this scenario on a granular packing driven mechanically below the Coulomb\nthreshold. We bring evidences for an effective viscous response directly\nrelated to small stress modulations in agreement with the theoretical\nprediction of a generic secular drift.",
        "positive": "Theory of active particle penetration through a planar elastic membrane: With the rapid advent of biomedical and biotechnological innovations, a deep\nunderstanding of the nature of interaction between nanomaterials and cell\nmembranes, tissues, and organs, has become increasingly important. Active\npenetration of nanoparticles through cell membranes is a fascinating phenomenon\nthat may have important implications in various biomedical and clinical\napplications. Using a fully analytical theory supplemented by particle-based\ncomputer simulations, the penetration process of an active particle through a\nplanar two-dimensional elastic membrane is studied. The membrane is modeled as\na self-assembled sheet of particles, uniformly arranged on a square lattice. A\ncoarse-grained model is introduced to describe the mutual interactions between\nthe membrane particles. The active penetrating particle is assumed to interact\nsterically with the membrane particles. State diagrams are presented to fully\ncharacterize the system behavior as functions of the relevant control\nparameters governing the transition between different dynamical states. Three\ndistinct scenarios are identified. These compromise trapping of the active\nparticle, penetration through the membrane with subsequent self-healing, in\naddition to penetration with permanent disruption of the membrane. The latter\nscenario is accompanied by a partial fragmentation of the membrane and creation\nof a hole of a size exceeding the interaction range of the membrane components.\nOur analytical theory is based on a combination of a perturbative expansion\ntechnique and a discrete-to-continuum formulation. Our approach might be\nhelpful for the prediction of the transition threshold between the trapping and\npenetration in real-space experiments involving motile swimming bacteria or\nartificial active particles."
    },
    {
        "anchor": "Colloidal smectics in button-like confinements: experiment and theory: Liquid crystals can self-organize into a layered smectic phase. While the\nsmectic layers are typically straight forming a lamellar pattern in bulk,\nexternal confinement may drastically distort the layers due to the boundary\nconditions imposed on the orientational director field. Resolving this\ndistortion leads to complex structures with topological defects. Here, we\nexplore the configurations adopted by two-dimensional colloidal smectics made\nfrom nearly hard rod-like particles in complex confinements, characterized by a\nbutton-like structure with two internal boundaries (inclusions): a two-holed\ndisk and a double annulus. The topology of the confinement generates new\nstructures which we classify in reference to previous work as generalized\nlaminar and generalized Shubnikov states. To explore these configurations, we\ncombine particle-resolved experiments on colloidal rods with three\ncomplementary theoretical approaches: Monte-Carlo simulation, first-principles\ndensity functional theory and phenomenological $\\mathbf{Q}$-tensor modeling.\nThis yields a consistent and comprehensive description of the structural\ndetails. In particular, we characterize a nontrivial tilt angle between the\ndirection of the layers and symmetry axes of the confinement.",
        "positive": "Thermal Dendrites on the Surface of Water and Water Solution: Thermal dendrites (fractal-like structures) on the surface of water and some\nwater solutions are found with an infrared camera. They are observed with\nspecific sizes and temperature differences in the liquid and are not associated\nwith the movement of the liquid."
    },
    {
        "anchor": "Lattice Boltzmann study of chemically-driven self-propelled droplets: We numerically study the behavior of self-propelled liquid droplets whose\nmotion is triggered by a Marangoni-like flow. This latter is generated by\nvariations of surfactant concentration which affect the droplet surface tension\npromoting its motion. In the present paper a model for droplets with a third\namphiphilic component is adopted. The dynamics is described by Navier-Stokes\nand convection-diffusion equations, solved by lattice Boltzmann method coupled\nwith finite-difference schemes. We focus on two cases. First the study of\nself-propulsion of an isolated droplet is carried on and, then, the interaction\nof two self-propelled droplets is investigated. In both cases, when the\nsurfactant migrates towards the interface, a quadrupolar vortex of the velocity\nfield forms inside the droplet and causes the motion. A weaker dipolar field\nemerges instead when the surfactant is mainly diluted in the bulk. The dynamics\nof two interacting droplets is more complex and strongly depends on their\nreciprocal distance. If, in a head-on collision, droplets are close enough, the\nvelocity field initially attracts them until a motionless steady state is\nachieved. If the droplets are vertically shifted, the hydrodynamic field leads\nto an initial reciprocal attraction followed by a scattering along opposite\ndirections. This hydrodynamic interaction acts on a separation of some droplet\nradii otherwise it becomes negligible and droplets motion is only driven by\nMarangoni effect. Finally, if one of the droplets is passive, this latter is\ngenerally advected by the fluid flow generated by the active one.",
        "positive": "Spontaneous stable rotation of flocking flexible active matter: In nature, active matter, such as worms or dogs, tend to spontaneously form a\nstable rotational cluster when they flock to the same food source on an\nunregulated and unconfined surface. {In this paper we present an $n$-node\nflexible active matter model to study the collective motion due to the flocking\nof individual agents on a two-dimensional surface, and confirm that there\nexists a spontaneous stable cluster rotation synchronizing with a chirality\nproduced by the alignment of their bodies under the impetus of the active\nforce.} A prefactor of 1.86 is obtained for the linear relationship between\nnormalized angular velocity and chirality. The angular velocity of such a\nrotation is found to be dependent on the individual flexibility, the number of\nnodes in each individual, and the magnitude of the active force. The\nconclusions well explain the spontaneous stable rotation of clusters that\nexists in many flexible active matter, like worms or {dogs}, when they flock to\nthe same single source."
    },
    {
        "anchor": "Classifying the age of a glass based on structural properties: A machine\n  learning approach: It is well established that physical aging of amorphous solids is governed by\na marked change in dynamical properties as the material becomes older.\nConversely, structural properties such as the radial distribution function\nexhibit only a very weak age dependence, usually deemed negligible with respect\nto the numerical noise. Here we demonstrate that the extremely weak\nage-dependent changes in structure are in fact sufficient to reliably assess\nthe age of a glass with the support of machine learning. We employ a supervised\nlearning method to predict the age of a glass based on the system's\ninstantaneous radial distribution function. Specifically, we train a multilayer\nperceptron for a model glassformer quenched to different temperatures, and find\nthat this neural network can accurately classify the age of our system across\nat least four orders of magnitude in time. Our analysis also reveals which\nstructural features encode the most useful information. Overall, this work\nshows that through the aid of machine learning, a simple structure-dynamics\nlink can indeed be established for physically aged glasses.",
        "positive": "Absorbing-state transitions in particulate systems under spatially\n  varying driving: We study the absorbing state transition in particulate systems under\nspatially inhomogeneous driving using a modified random organization model. For\nsmoothly varying driving the steady state results map onto the homogeneous\nabsorbing state phase diagram, with the position of the boundary between\nabsorbing and diffusive states being insensitive to the driving wavelength.\nHere the phenomenology is well-described by a one-dimensional continuum model\nthat we pose. For discontinuously varying driving the position of the absorbing\nphase boundary and the exponent characterising the fraction of active particles\nare altered relative to the homogeneous case."
    },
    {
        "anchor": "Rods are less fragile than spheres: Structural relaxation in dense\n  liquids composed of anisotropic particles: We perform extensive molecular dynamics simulations of dense liquids composed\nof bidisperse dimer- and ellipse-shaped particles in 2D that interact via\nrepulsive contact forces. We measure the structural relaxation times obtained\nfrom the long-time decay of the self-part of the intermediate scattering\nfunction for the translational and rotational degrees of freedom (DOF) as a\nfunction of packing fraction \\phi, temperature T, and aspect ratio \\alpha. We\nare able to collapse the \\phi and T-dependent structural relaxation times for\ndisks, and dimers and ellipses over a wide range of \\alpha, onto a universal\nscaling function {\\cal F}_{\\pm}(|\\phi-\\phi_0|,T,\\alpha), which is similar to\nthat employed in previous studies of dense liquids composed of purely repulsive\nspherical particles in 3D. {\\cal F_{\\pm}} for both the translational and\nrotational DOF are characterized by the \\alpha-dependent scaling exponents \\mu\nand \\delta and packing fraction \\phi_0(\\alpha) that signals the crossover in\nthe scaling form {\\cal F}_{\\pm} from hard-particle dynamics to super-Arrhenius\nbehavior for each aspect ratio. We find that the fragility at \\phi_0,\nm(\\phi_0), decreases monotonically with increasing aspect ratio for both\nellipses and dimers. Moreover, the results for the slow dynamics of dense\nliquids composed of dimer- and ellipse-shaped particles are qualitatively the\nsame, despite the fact that zero-temperature static packings of dimers are\nisostatic, while static packings of ellipses are hypostatic.",
        "positive": "Fluctuation tension and shape transition of vesicles: renormalisation\n  calculations and Monte Carlo simulations: It has been known for long that the fluctuation surface tension of membranes\n$r$, computed from the height fluctuation spectrum, is not equal to the bare\nsurface tension $\\sigma$ introduced in the Helfrich theory. In this work we\nrelate these two surface tensions both analytically and numerically and compare\nthem to the Laplace tension $\\gamma$, and the mechanical frame tension $\\tau$.\nUsing one-loop renormalisation calculations, we obtain, in addition to the\neffective bending modulus $\\kappa_{\\rm eff}$, a new expression for the\neffective surface tension $\\sigma_{\\rm eff}=\\sigma - \\epsilon k_{\\rm\nB}T/(2a_p)$ where $a_p$ the projected cut-off area, and $\\epsilon=3$ or 1\naccording to the allowed configurations. Moreover we show that the crumpling\ntransition for an infinite planar membrane occurs for $\\sigma_{\\rm eff}=0$, and\nalso that it coincides with vanishing Laplace and frame tensions. Using\nextensive Monte Carlo (MC) simulations, triangulated membranes of vesicles made\nof $N=100-2500$ vertices are simulated. No local constraint is applied. It is\nshown that the numerical $r$ is equal to $\\sigma_{\\rm eff}$ both with radial MC\nmoves ($\\epsilon=3$) and with corrected MC moves locally normal to the\nfluctuating membrane ($\\epsilon=1$). For finite vesicles of typical size $R$,\ntwo different regimes are defined: a tension regime for $\\hat \\sigma_{\\rm\neff}=\\sigma_{\\rm eff}R^2/\\kappa_{\\rm eff}>0$ and a bending one for $-1<\\hat\n\\sigma_{\\rm eff}<0$. A shape transition from a quasi-spherical shape imposed by\nthe large surface energy, to more deformed shapes only controlled by the\nbending energy, is observed numerically at $\\hat \\sigma_{\\rm eff}\\simeq 0$. We\npropose that the buckling transition, observed for planar supported membranes\nin the literature, occurs for $\\hat \\sigma_{\\rm eff}\\simeq-1$, the associated\nnegative frame tension playing the role of a compressive force."
    },
    {
        "anchor": "Controlled gel expansion through colloid oscillation: We model the behaviour of a single colloid embedded in a cross-linked polymer\ngel, immersed in a viscous background fluid. External fields actuate the\nparticle into a periodic motion, which deforms the embedding matrix and creates\na local micro-cavity, containing the particle and any free volume created by\nits motion. This cavity exists only as long as the particle is actuated and,\nwhen present, reduces the local density of the material, leading to swelling.\nWe show that the model exhibits rich resonance features, but is overall\ncharacterised by clear scaling laws at low and high driving frequencies, and a\npronounced resonance at intermediate frequencies. Our model predictions suggest\nthat both the magnitude and position of the resonance can be varied by varying\nthe material's elastic modulus or cross-linking density, whereas the local\nviscosity primarily has a dampening effect. Our work implies appreciable\nfree-volume generation is possible by dispersing a collection of colloids in\nthe medium, even at the level of a simple superposition approximation.",
        "positive": "Using single nanoparticle tracking obtained by nanophotonic force\n  microscopy to simultaneously characterize nanoparticle size distribution and\n  nanoparticle-surface interactions: Comprehensive characterization of nanomaterials for medical applications is a\nchallenging and complex task due to the multitude of parameters which need to\nbe taken into consideration in a broad range of conditions. Routine methods\nsuch as dynamic light scattering or nanoparticle tracking analysis provide some\ninsight into the physicochemical properties of particle dispersions. For\nnanomedicine applications the information they supply can be of limited use.\nFor this reason, there is a need for new methodologies and instruments that can\nprovide additional data on nanoparticle properties such as their interactions\nwith surfaces. Nanophotonic force microscopy has been shown as a viable method\nfor measuring the force between surfaces and individual particles in the\nnano-size range. Here we outline a further application of this technique to\nmeasure the size of single particles and based on these measurement build the\ndistribution of a sample. We demonstrate its efficacy by comparing the size\ndistribution obtained with nanophotonic force microscopy to established\ninstruments, such as dynamic light scattering and differential centrifugal\nsedimentation. Our results were in good agreement to those observed with all\nother instruments. Furthermore, we demonstrate that the methodology developed\nin this work can be used to study complex particle mixtures and the surface\nalteration of materials. For all cases studied, we were able to obtain both the\nsize and the interaction potential of the particles with a surface in a single\nmeasurement."
    },
    {
        "anchor": "Membrane stress tensor in the presence of lipid density and composition\n  inhomogeneities: We derive the expression of the stress tensor for one and two-component lipid\nmembranes with density and composition inhomogeneities. We first express the\nmembrane stress tensor as a function of the free-energy density by means of the\nprinciple of virtual work. We then apply this general result to a monolayer\nmodel which is shown to be a local version of the area-difference elasticity\n(ADE) model. The resulting stress tensor expression generalizes the one\nassociated with the Helfrich model, and can be specialized to obtain the one\nassociated with the ADE model. Our stress tensor directly gives the force\nexchanged through a boundary in a monolayer with density and composition\ninhomogeneities. Besides, it yields the force density, which is also directly\nobtained in covariant formalism. We apply our results to study the forces\ninduced in a membrane by a local perturbation.",
        "positive": "Monodisperse cluster crystals: classical and quantum dynamics: We study the phases and dynamics of a gas of monodisperse particles\ninteracting via soft-core potentials in two spatial dimensions, which is of\ninterest for soft-matter colloidal systems and quantum atomic gases. Using\nexact theoretical methods, we demonstrate that the equilibrium low-temperature\nclassical phase simultaneously breaks continuous translational symmetry and\ndynamic space-time homogeneity, whose absence is usually associated with\nout-of-equilibrium glassy phenomena. This results in an exotic self-assembled\ncluster crystal with coexisting liquid-like long-time dynamical properties,\nwhich corresponds to a classical analog of supersolid behavior. We demonstrate\nthat the effects of quantum fluctuations and bosonic statistics on\ncluster-glassy crystals are separate and competing: zero-point motion tends to\ndestabilize crystalline order, which can be restored by bosonic statistics."
    },
    {
        "anchor": "Transport in polymer membranes beyond linear response: Controlling\n  permselectivity by the driving force: In the popular solution-diffusion picture, the membrane permeability is\ndefined as the product of the partition ratio and the diffusivity of\npenetrating solutes inside the membrane in the linear response regime, i.e., in\nequilibrium. However, of practical importance is the penetrants' flux across\nthe membrane driven by external forces. Here, we study nonequilibrium membrane\npermeation orchestrated by a uniform external driving field using molecular\ncomputer simulations and continuum (Smoluchowski) theory in the stationary\nstate. In the simulations, we explicitly resolve the penetrants' transport\nacross a finite monomer-resolved polymer network, addressing one-component\npenetrant systems and mixtures. We introduce and discuss possible definitions\nof nonequilibrium, force-dependent permeability, representing `system' and\n`membrane' permeability. In particular, we present for the first time a\ndefinition of the differential permeability response to the force. We\ndemonstrate that the latter turns out to be significantly nonlinear for\nlow-permeable systems, leading to a high amount of selectiveness in\npermeability, called `permselectivity', and is tunable by the driving force.\nOur continuum-level analytical solutions exhibit remarkable qualitative\nagreement with the penetrant- and polymer-resolved simulations, thereby\nallowing us to characterize the underlying mechanism of permeabilities and\nsteady-state transport beyond the linear response level.",
        "positive": "Shannon entropy analysis of the stretched exponential process :\n  application to various shear induced multilamellar vesicles system: The stretched exponential function, $\\exp[-(t/\\tau_{K})^{\\beta}]$, describes\nvarious relaxation processes while it has been suggested that the power\nexponent, $\\beta$ is derived from the non-uniformity of the process. In this\npaper, we attempted to estimate this non-uniformity by introducing Shannon\nentropy. Shannon entropy evaluates the average information contents of the\ndistribution function, which reflects statistical homogeneity. We investigated\nthe relaxation process of shear induced multilamellar system, which is\ndescribed with the stretched exponential function. Three types of shear\n(constant, square, sine) at different frequencies are attempted in order to\ndetermine their effects on the relaxation process. We found that the Shannon\nentropy to which the first moment was introduced is maximized at $\\beta~=~1$ :\na single exponential. The Shannon entropy of sine shear experiments exhibited\nthe frequency dependence. Thus it is interpreted that the increase of the\nintensity of shearing and the thermodynamic entropy are reflected on the\nShannon entropy. We discussed the meaning of the maximum Shannon entropy in\nterms of various points of view, it was found that it corresponds to the\ndiffusion process free from the restriction such as geometrical constraints.\nThe constraints and the non-uniformity of process were successfully estimated\nby Shannon entropy. This study gives a new insight of entropy in general."
    },
    {
        "anchor": "Field-induced layer thinning transition on free-standing smectic films: Strongly anchored free-standing smectic films usually present a stepwise\nreduction of the number of layers when the temperature is raised above the\nsmectic-isotropic bulk transition temperature. Here, we demonstrate that a\nfield-induced layer thinning transition can take place in smectic films with a\nnegative dielectric anisotropy even below the bulk transition temperature.\nUsing an extended McMillan's model, we provide the phase diagram of this\nlayering transition and show that, when the field is raised above the bulk\ntransition field, the film thickness reduction is well described by a power-law\nwith an exponent that depends on the temperature and the aspect ratio of the\nliquid crystal molecule.",
        "positive": "Role of Hydrodynamic Drainage in Adhesion to Wet Surfaces: Tree frogs possess soft structured toe pads with channels that help squeeze\nout fluid from the region between the toe pad and the contacting surfaces. This\nstructure enables them to walk on wet and rough surfaces. We present our\npreliminary result aiming at understanding the role of surface structure on\nhydrodynamic drainage forces. We have used the surface forces apparatus to\nmeasure the drainage forces (approach and retraction) in silicone oil. We\ncompare the drainage force measured between two smooth PMMA surfaces with the\none measure when one of the two surfaces has a structure with channels. We have\nobserved that the presence of channels reduces the hydrodynamic drainage forces\nwhen the surfaces come together and reduces the adhesion when the surfaces are\npulled apart. Our force measurements were compared to Reynolds theory and we\ndiscuss the possible role of elastohydrodynamic deformation in tree frog\nadhesion."
    },
    {
        "anchor": "Granular gases in mechanical engineering: on the origin of heterogeneous\n  ultrasonic shot peening: The behavior of an ultrasonic shot peening process is observed and analyzed\nby using a model of inelastic hard spheres in a gravitational field that are\nfluidized by a vibrating bottom wall (sonotrode) in a cylindrical chamber. A\nmarked heterogeneous distribution of impacts appears when the collision between\nthe shot and the side wall becomes inelastic with constant dissipation. This\neffect is one order of magnitude larger than the simple heterogeneity arising\nfrom boundary collision on the cylinder. Variable restitution coefficients\nbring the simulation closer to the general observation and allows the\ninvestigation of peening regimes with changing shot density. We compute within\nthis model other physical quantities (impact velocities, impact angle,\ntemperature and density profile) that are influenced by the number $N$ of\nspheres.",
        "positive": "Stress-controlled medium-amplitude oscillatory shear (MAOStress) of\n  PVA-Borax: We report the first-ever complete measurement of MAOStress material\nfunctions, which reveal that stress can be more fundamental than strain or\nstrain rate for understanding linearity limits as a function of Deborah number.\nThe material used is a canonical viscoelastic liquid with a single dominant\nrelaxation time: Polyvinyl alcohol (PVA) polymer solution crosslinked with\ntetrahydroborate (Borax) solution. We outline experimental limit lines and\ntheir dependence on geometry and test conditions. These MAOStress measurements\nenable us to observe the frequency dependence of the weakly nonlinear deviation\nas a function of stress amplitude. The observed features of MAOStress material\nfunctions are distinctly simpler than MAOStrain, where the frequency dependence\nis much more dramatic. The strain-stiffening transient network model (SSTNM)\nwas used to derive a model-informed normalization of the nonlinear material\nfunctions that accounts for their scaling with the linear material properties.\nMoreover, we compare the frequency-dependence of the critical stress, strain,\nand strain-rate for the linearity limit, which are rigorously computed from the\nMAOStress and MAOStrain material functions. While critical strain and\nstrain-rate change by orders of magnitude throughout the Deborah number range,\nthe critical stress changes by a factor of about two, showing that stress is a\nmore fundamental measure of nonlinearity strength. This work extends the\nexperimental accessibility of the weakly nonlinear regime to stress-controlled\ninstruments and deformations, which reveal material physics beyond linear\nviscoelasticity but at conditions that are accessible to theory and detailed\nsimulation."
    },
    {
        "anchor": "Phase Separation in Symmetric Mixtures of Oppositely Charged Rodlike\n  Polyelectrolytes: Phase separation in salt-free symmetric mixtures of oppositely charged\nrodlike polyelectrolytes is studied using quasi-analytical calculations.\nStability analyses for the isotropic-isotropic and the isotropic-nematic phase\ntransitions in the mixtures are carried out and demonstrate that electrostatic\ninteractions favor nematic ordering. Coexistence curves for the symmetric\nmixtures are also constructed and are used to examine the effects of linear\ncharge density and electrostatic interaction strength on rodlike\npolyelectrolyte complexation. It is found that the counterions are uni- formly\ndistributed in the coexisting phases for low electrostatic interaction\nstrengths dictated by the linear charge density of the polyelectrolytes and\nBjerrum's length. However, the counterions also partition along with the\nrodlike polyelectrolytes with an increase in the electrostatic interaction\nstrength. It is shown that the number density of the counterions is higher in\nthe concentrated (or \"coacervate\") phase than in the dilute (or supernatant)\nphase. In contrast to such rodlike mixtures, flexible polyelectrolyte mixtures\ncan undergo only isotropic-isotropic phase separation. A comparison of the\ncoexistence curves for weakly-charged rodlike mixtures with those of analogous\nflexible polyelectrolyte mixtures reveals that the electrostatic driving force\nfor the isotropic-isotropic phase separation is stronger in the flexible\nmixtures.",
        "positive": "Comparing kinetic Monte Carlo and Thin-Film Modeling of Transversal\n  Instabilities of Ridges on Patterned Substrates: We employ kinetic Monte Carlo (KMC) simulations and a thin-film continuum\nmodel to comparatively study the transverse (i.e., Plateau-Rayleigh)\ninstability of ridges formed by molecules on pre-patterned substrates. It is\ndemonstrated that the evolution of the occurring instability qualitatively\nagrees between the two models for a single ridge as well as for two weakly\ninteracting ridges. In particular, it is shown for both models that the\ninstability occurs on well defined length and time scales which are, for the\nKMC model, significantly larger than the intrinsic scales of thermodynamic\nfluctuations. This is further evidenced by the similarity of dispersion\nrelations characterising the linear instability modes."
    },
    {
        "anchor": "Electric-field-induced topological changes in multilamellar and in\n  confined lipid membranes: It is well known that lipid membranes respond to a threshold transmembrane\nelectric field through a reversible mechanism called electroporation, where\nhydrophilic water pores form across the membrane, an effect widely used in\nbiological systems. The effect of such fields on interfacially-confined\n(stacked or supported) lipid membranes, on the other hand, which may strongly\nmodulate interfacial properties, has not to our knowledge been previously\nstudied. Motivated by recent surface forces experiments showing a striking\neffect of electric fields on lubrication by confined lipid bilayers, we carried\nout all-atom molecular dynamics simulations of such membranes under transverse\nelectric fields. We find that in addition to electroporation, a new feature\nemerges of locally merged bilayers which act to bridge the confining\ninterfaces. These features shed light on the remodelling of confined lipid\nmembrane stacks by electric fields, and provides insight into how such fields\nmay modulate frictional and more generally surface interactions in the presence\nof lipid-based boundary layers.",
        "positive": "Elastic interactions in damage models of brittle failure: The failure of brittle solids involves, before macroscopic rupture, power-law\ndistributed avalanches of local rupture events whereby microcracks nucleate and\ngrow, which are also observed in for an elastic interface evolving in a\nnon-homogeneous medium. For this reason, it is tempting to relate failure to\nthe depinning of an elastic interface. Here we compute the elastic kernel of\nthe interface representing the damage field of a brittle solid. In the case of\na damage model of rupture under compression, which implements the Mohr-Coulomb\ncriterion at the local scale, we show that the elastic kernel is unstable, and\nhence is very different from the kernels of usual interfaces. We show that the\nunstable modes are responsible for the localization of damage along a\nmacroscopic fault observed in numerical simulations. At low disorder, the most\nunstable mode gives the orientation of the macroscopic fault that we measure in\nnumerical simulations. The orientation of the fault changes when the level of\ndisorder is increased, suggesting a complex interplay of the unstable modes and\nthe disorder."
    },
    {
        "anchor": "Constraints, Histones, and the 30 Nanometer Spiral: We investigate the mechanical stability of a segment of DNA wrapped around a\nhistone in the nucleosome configuration. The assumption underlying this\ninvestigation is that the proper model for this packaging arrangement is that\nof an elastic rod that is free to twist and that writhes subject to mechanical\nconstraints. We find that the number of constraints required to stabilize the\nnuclesome configuration is determined by the length of the segment, the number\nof times the DNA wraps around the histone spool, and the specific constraints\nutilized. While it can be shown that four constraints suffice, in principle, to\ninsure stability of the nucleosome, a proper choice must be made to guarantee\nthe effectiveness of this minimal number. The optimal choice of constraints\nappears to bear a relation to the existence of a spiral ridge on the surface of\nthe histone octamer. The particular configuration that we investigate is\nrelated to the 30 nanometer spiral, a higher-order organization of DNA in\nchromatin.",
        "positive": "Universal Scaling of Polygonal Desiccation Crack Patterns: Polygonal desiccation crack patterns are commonly observed in natural\nsystems. Despite their quotidian nature, it is unclear whether similar crack\npatterns which span orders of magnitude in length scales share the same\nunderlying physics. In thin films, the characteristic length of polygonal\ncracks is known to monotonically increase with the film thickness, however,\nexisting theories that consider the mechanical, thermodynamic, hydrodynamic,\nand statistical properties of cracking often lead to contradictory predictions.\nHere we experimentally investigate polygonal cracks in drying suspensions of\nmicron-sized particles by varying film thickness, boundary adhesion, packing\nfraction, and solvent. Although polygonal cracks were observed in most systems\nabove a critical film thickness, in cornstarch-water mixtures, multi-scale\ncrack patterns were observed due to two distinct desiccation mechanisms.\nLarge-scale, primary polygons initially form due to capillary-induced film\nshrinkage, whereas small-scale, secondary polygons appear later due to the\ndeswelling of the hygroscopic particles. In addition, we find that the\ncharacteristic area of the polygonal cracks, $A_p$, obeys a universal power\nlaw, $A_p=\\alpha h^{4/3}$, where $h$ is the film thickness. By quantitatively\nlinking $\\alpha$ with the material properties during crack formation, we\nprovide a robust framework for understanding multi-scale polygonal crack\npatterns from microscopic to geologic scales."
    },
    {
        "anchor": "Dynamic scaling for the growth of non-equilibrium fluctuations during\n  thermophoretic diffusion in microgravity: Diffusion processes are widespread in biological and chemical systems, where\nthey play a fundamental role in the exchange of substances at the cellular\nlevel and in determining the rate of chemical reactions. Recently, the\nclassical picture that portrays diffusion as random uncorrelated motion of\nmolecules has been revised, when it was shown that giant non-equilibrium\nfluctuations develop during diffusion processes. Under microgravity conditions\nand at steady-state, non-equilibrium fluctuations exhibit scale invariance and\ntheir size is only limited by the boundaries of the system. In this work, we\ninvestigate the onset of non-equilibrium concentration fluctuations induced by\nthermophoretic diffusion in microgravity, a regime not accessible to analytical\ncalculations but of great relevance for the understanding of several natural\nand technological processes. A combination of state of the art simulations and\nexperiments allows us to attain a fully quantitative description of the\ndevelopment of fluctuations during transient diffusion in microgravity. Both\nexperiments and simulations show that during the onset the fluctuations exhibit\nscale invariance at large wave vectors. In a broader range of wave vectors\nsimulations predict a spinodal-like growth of fluctuations, where the amplitude\nand length-scale of the dominant mode are determined by the thickness of the\ndiffuse layer.",
        "positive": "Complex electric double layers in charged topological colloids: Charged surfaces in contact with liquids containing ions are accompanied in\nequilibrium by an electric double layer consisting of a layer of electric\ncharge on the surface that is screened by a diffuse ion cloud in the bulk\nfluid. This screening cloud determines not only the interactions between\ncharged colloidal particles or polyelectrolytes and their self-assembly into\nordered structures, but it is also pivotal in understanding energy storage\ndevices, such as electrochemical cells and supercapacitors. However, little is\nknown to what spatial complexity the electric double layers can be designed.\nHere, we show that electric double layers of non-trivial topology and geometry\n-including tori, multi-tori and knots- can be realised in charged topological\ncolloidal particles, using numerical modelling within a mean-field\nPoisson-Boltzmann theory. We show that the complexity of double layers\n-including geometry and topology- can be tuned by changing the Debye screening\nlength of the medium, or by changing the shape and topology of the (colloidal)\nparticle. More generally, this work is an attempt to introduce concepts of\ntopology in the field of charged colloids, which could lead to novel exciting\nmaterial design paradigms."
    },
    {
        "anchor": "What buoyancy really is. A Generalized Archimedes Principle for\n  sedimentation and ultracentrifugation: Particle settling is a pervasive process in nature, and centrifugation is a\nmuch versatile separation technique. Yet, the results of settling and\nultracentrifugation experiments often appear to contradict the very law on\nwhich they are based: Archimedes Principle - arguably, the oldest Physical Law.\nThe purpose of this paper is delving at the very roots of the concept of\nbuoyancy by means of a combined experimental-theoretical study on sedimentation\nprofiles in colloidal mixtures. Our analysis shows that the standard\nArchimedes' principle is only a limiting approximation, valid for mesoscopic\nparticles settling in a molecular fluid, and we provide a general expression\nfor the actual buoyancy force. This \"Generalized Archimedes Principle\" accounts\nfor unexpected effects, such as denser particles floating on top of a lighter\nfluid, which in fact we observe in our experiments.",
        "positive": "Uniaxial and biaxial structures in the elastic Maier-Saupe model: We perform statistical mechanics calculations to analyze the global phase\ndiagram of a fully-connected version of a Maier-Saupe-Zwanzig lattice model\nwith the inclusion of couplings to an elastic strain field. We point out the\npresence of uniaxial and biaxial nematic structures, depending on temperature\n$T$ and on the applied stress $\\sigma$. Under uniaxial extensive tension,\napplied stress favors uniaxial orientation, and we obtain a first-order\nboundary, along which there is a coexistence of two uniaxial paranematic\nphases, and which ends at a simple critical point. Under uniaxial compressive\ntension, stress favors biaxial orientation; for small values of the coupling\nparameters, the first-order boundary ends at a tricritical point, beyond which\nthere is a continuous transition between a paranematic and a biaxially ordered\nstructure. For some representative choices of the model parameters, we obtain a\nnumber of analytic results, including the location of critical and tricritical\npoints and the line of stability of the biaxial phase."
    },
    {
        "anchor": "A Stochastic Immersed Boundary Method for Fluid-Structure Dynamics at\n  Microscopic Length Scales: In this work it is shown how the immersed boundary method of (Peskin2002) for\nmodeling flexible structures immersed in a fluid can be extended to include\nthermal fluctuations. A stochastic numerical method is proposed which deals\nwith stiffness in the system of equations by handling systematically the\nstatistical contributions of the fastest dynamics of the fluid and immersed\nstructures over long time steps. An important feature of the numerical method\nis that time steps can be taken in which the degrees of freedom of the fluid\nare completely underresolved, partially resolved, or fully resolved while\nretaining a good level of accuracy. Error estimates in each of these regimes\nare given for the method. A number of theoretical and numerical checks are\nfurthermore performed to assess its physical fidelity. For a conservative\nforce, the method is found to simulate particles with the correct Boltzmann\nequilibrium statistics. It is shown in three dimensions that the diffusion of\nimmersed particles simulated with the method has the correct scaling in the\nphysical parameters. The method is also shown to reproduce a well-known\nhydrodynamic effect of a Brownian particle in which the velocity\nautocorrelation function exhibits an algebraic tau^(-3/2) decay for long times.\nA few preliminary results are presented for more complex systems which\ndemonstrate some potential application areas of the method.",
        "positive": "How to Study a Persistent Active Glassy System?: We explore glassy dynamics of dense assemblies of soft particles that are\nself-propelled by active forces. These forces have a fixed amplitude and a\npropulsion direction that varies on a timescale tau_p, the persistence\ntimescale. Numerical simulations of such active glasses are computationally\nchallenging when the dynamics is governed by large persistence times. We\ndescribe in detail a recently proposed scheme that allows one to study directly\nthe dynamics in the large persistence time limit, on timecales around and well\nabove the persistence time. We discuss the idea behind the proposed scheme,\nwhich we call activity-driven dynamics, as well as its numerical\nimplementation. We establish that our prescription faithfully reproduces all\ndynamical quantities in the appropriate limit tau_p goes to infinity. We deploy\nthe approach to explore in detail the statistics of Eshelby-like plastic events\nin the steady state dynamics of a dense and intermittent active glass."
    },
    {
        "anchor": "Nonequilibrium continuous phase transition in colloidal gelation with\n  short-range attraction: The dynamical arrest of attractive colloidal particles into\nout-of-equilibrium structures, known as gelation, is central to biophysics,\nmaterials science, nanotechnology, and food and cosmetic applications, but a\ncomplete understanding is lacking. In particular, for intermediate particle\ndensity and attraction, the structure formation process remains unclear. Here,\nwe show that the gelation of short-range attractive particles is governed by a\nnonequilibrium percolation process. We combine experiments on critical Casimir\ncolloidal suspensions, numerical simulations, and analytical modeling with a\nmaster kinetic equation to show that cluster sizes and correlation lengths\ndiverge with exponents 1.6 and 0.8, respectively, consistent with percolation\ntheory, while detailed balance in the particle attachment and detachment\nprocesses is broken. Cluster masses exhibit power-law distributions with\nexponents -3/2 and -5/2 before and after percolation, as predicted by solutions\nto the master kinetic equation. These results revealing a nonequilibrium\ncontinuous phase transition unify the structural arrest and yielding into\nrelated frameworks.",
        "positive": "Tetrahedral entropy captures non-monotonicity of electrical conductivity\n  in aqueous monatomic ions: The intriguing relationship between entropy and diffusion is a subject of\nmuch current interest. However, the experimentally observed unusual\nnon-monotonic dependence of limiting ionic conductivity on inverse ion size is\nneither described by the Adam-Gibbs entropy crisis theory nor by the Rosenfeld\nentropy scaling. This failure is obvious because throughout the size variation\nthe bulk entropy of the solvent remains the same, or undergoes infinitesimal\nchange. We show that it is the entropy experienced by the tagged ion that needs\nto be calculated. This entropy can be quantified, at least partly, by the\nchange in the tetrahedral ordering of water molecules in the hydration layer of\nthe ions which exhibits a nonmonotonic size dependence."
    },
    {
        "anchor": "Trapping Instability of an Active Particle in Steering Potential Fields: A particle driven by active self-propulsion can be subject to inhomogeneous\npotential fields, steering its orientation and leading to confinement and\neventual trapping. Analytical treatment of capture and/or release dynamics for\ngeneral steering potentials presents a challenge due to its coupling between\nexternal potential fields and intrinsic active noise. By using the projection\noperator method we obtain the coarse-grained Dynkin equations with orientation\nintegrated out in the large fluctuations limit, and derive explicit analytical\nsolutions for the mean first passage time in radially symmetric point source\ntrapping potentials. We analyze the ensuing trapping instabilities related to a\ncritical value of the steering potential strength below which the particle\neither cannot be lured into the trap, or above which it is unable to leave the\ntrap after being lured into it.",
        "positive": "Anomalous Melting Scenario of the Two-Dimensional Core-Softened System: We consider the phase behavior of two-dimensional ($2D$)system of particles\nwith an isotropic core-softened potential introduced in our previous\npublications. As one can expect from the qualitative consideration for the\nthree dimensional case, the system demonstrates a reentrant-melting transition\nat low densities along with waterlike anomalies in the fluid phase near the\nmelting maximum. In contrast with the three dimensional case, in two dimensions\nmelting is a continuous two-stage transition in the low density part of the\nphase diagram with an intermediate hexatic phase corresponding to the\nKosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) scenario. At the same time,\nat high densities the system melts through one first-order transition. We also\nshow, that the order of the region of anomalous diffusion and the regions of\ndensity and structural anomalies are inverted in comparison with the $3D$ case\nand have silicalike sequence."
    },
    {
        "anchor": "Apparent molar volume anomaly in water-dimethyl sulfoxide liquid\n  mixtures. Molecular dynamics computer simulations: We have studied the composition dependence of density of liquid water-DMSO\nmixtures at different temperatures by using the isobaric-isothermal (NPT)\nmolecular dynamics computer simulations. The non-polarizable semi-flexible, P1\nand P2 models for the DMSO molecule combined with the TIP4P-2005 water model\nare considered. The excess mixing volume and the apparent molar volumes of the\nspecies are reported. We have established that the P1-TIP4P-2005 model for the\nmixture provides a very good description of the location of the minimum of\napparent molar volume for DMSO species indicating the anomaly. Most important\nis that the temperature interval where the hydrophobic effect exists, is\ncorrectly captured with this modelling, in contrast to the P2-TIP4P-2005 model.",
        "positive": "The glass transition of glycerol in the volume-temperature plane: We assess the relative importance of spatial congestion and lowered\ntemperature in the slowing dynamics of supercooled glycerol near the glass\ntransition. We independently vary both volume, V, and temperature, T, by\napplying high pressure and monitor the dynamics by measuring the dielectric\nsusceptibility. Our results demonstrate that both variables are control\nvariables of comparable importance. However, a generalization of the concept of\nfragility of a glass-former shows that the dynamics are quantitatively more\nsensitive to fractional changes in V than T. We identify a connection between\nthe fragility and a recently proposed density-temperature scaling which\nindicates that this conclusion holds for other liquids and polymers."
    },
    {
        "anchor": "Interfacial transport with mobile surface charges and consequences for\n  ionic transport in carbon nanotubes: In this paper, we explore the effect of a finite surface charge mobility on\nthe interfacial transport: conductance, streaming currents, electro- and\ndiffusio-osmotic flows. We first show that the surface charge mobility modifies\nthe hydrodynamic boundary condition for the fluid, which introduces a\nsupplementary term depending on the applied electric field. In particular, the\nresulting slip length is found to decrease inversely with the surface charge.\nWe then derive expressions for the various transport mobilities, high-lighting\nthat the surface charge mobility merely moderates the amplification effect of\ninterfacial slippage, to the noticeable exception of diffusio-osmosis and\nsurface conductance. Our calculations, obtained within Poisson-Boltzmann\nframework, highlight the importance of non-linear electrostatic contributions\nto predict the small concentration/large charge limiting regimes for the\ntransport mobilities. We discuss these predictions in the context of recent\nelectrokinetic experiments with carbon nanotubes.",
        "positive": "$\\mathcal {C}-$IBI: Targeting cumulative coordination within an\n  iterative protocol to derive coarse-grained models of (multi-component)\n  complex fluids: We present a coarse-graining strategy that we test for aqueous mixtures. The\nmethod uses pair-wise cumulative coordination as a target function within an\niterative Boltzmann inversion (IBI) like protocol. We name this method\ncoordination iterative Boltzmann inversion ($\\mathcal {C}-$IBI). While the\nunderlying coarse-grained model is still structure based and, thus, preserves\npair-wise solution structure, our method also reproduces solvation\nthermodynamics of binary and/or ternary mixtures. Additionally, we observe much\nfaster convergence within $\\mathcal {C}-$IBI compared to IBI. To validate the\nrobustness, we apply $\\mathcal {C}-$IBI to study test cases of solvation\nthermodynamics of aqueous urea and a triglycine solvation in aqueous urea."
    },
    {
        "anchor": "Correlations in a polymeric structure immersed in a magnetic solution: Polymers are among the most important materials in the modern society being\nfound almost in every activity of our daily life. Understanding their chemical\nand physical properties lead to improvements of their usage. The correlation\nfunctions are one of most important quantities to understand a physical system.\nThe characteristic way it behaves describe how the system fluctuates, and much\nof the progress achieved to understand complex systems has been due to their\nstudy. Of particular interest in polymer science are the space correlations\nwhich describe its mechanical behavior. In this work I study the stiffness of a\npolymer immersed in a magnetic medium and trapped in an optical tweezers. Using\nMonte Carlo simulations the correlation function along the chain and the force\nin the tweezers are obtained as a function of temperature and density of\nmagnetic particles. The results show that the correlation decay has two\nregimes: an initial very fast decay of order the monomer-monomer spacing and a\npower law in the long distance regime. The power law exponent has a minimum at\na temperature $T_{min}$ for any non zero density of magnetic particles\nindicating that the system is more correlated in this region. Using a formula\nfor the persistence length derived from the WLC theory one observed that it has\na maximum at the same temperature. These results suggest that the correlations\nin the system may be a combination of exponential and power law.",
        "positive": "Transient electrophoretic current in a nonpolar solvent: The transient electric current of surfactants dissolved in a nonpolar solvent\nis investigated both experimentally and theoretically in the parallel-plate\ngeometry. Due to a low concentration of free charges the cell can be completely\npolarized by an external voltage of several volts. In this state, all the\ncharged micelles are compacted against the electrodes. After the voltage is set\nto zero the reverse current features a sharp discharge spike and a broad peak.\nThis shape and its variation with the compacting voltage are reproduced in a\none-dimensional drift-diffusion model. The model reveals the broad peak is\nformed by a competition between an increasing number of charges drifting back\nto the middle of the cell and a decreasing electric field that drives the\nmotion. After complete polarization is achieved, the shape of the peak stops\nevolving with further increase of the compacting voltage. The spike-peak\nseparation time grows logarithmically with the charge content in the bulk. The\ntime peak is a useful measure of the micelle mobility. Time integration of the\npeak yields the total charge in the system. By measuring its variation with\ntemperature, the activation energy of bulk charge generation has been found to\nbe 0.126 eV."
    },
    {
        "anchor": "Friction law and hysteresis in granular materials: The macroscopic friction of particulate materials often weakens as the flow\nrate is increased, leading to potentially disastrous intermittent phenomena\nincluding earthquakes and landslides. We theoretically and numerically study\nthis phenomenon in simple granular materials. We show that velocity-weakening,\ncorresponding to a non-monotonic behavior in the friction law $\\mu(I)$, is\npresent even if the dynamic and static microscopic friction coefficients are\nidentical, but disappears for softer particles. We argue that this instability\nis induced by endogenous acoustic noise, which tends to make contacts slide,\nleading to faster flow and increased noise. We show that soft spots, or\nexcitable regions in the materials, correspond to rolling contacts that are\nabout to slide, whose density is described by a nontrivial exponent $\\theta_s$.\nWe build a microscopic theory for the non-monotonicity of $\\mu(I)$, which also\npredicts the scaling behavior of acoustic noise, the fraction of sliding\ncontacts $\\chi$ and the sliding velocity, in terms of $\\theta_s$. Surprisingly,\nthese quantities have no limit when particles become infinitely hard, as\nconfirmed numerically. Our analysis rationalizes previously unexplained\nobservations and makes new experimentally testable predictions.",
        "positive": "Phase-field model for Hele-Shaw flows with arbitrary viscosity contrast.\n  II. Numerical study: We implement a phase-field simulation of the dynamics of two fluids with\narbitrary viscosity contrast in a rectangular Hele-Shaw cell. We demonstrate\nthe use of this technique in different situations including the linear regime,\nthe stationary Saffman-Taylor fingers and the multifinger competition dynamics,\nfor different viscosity contrasts. The method is quantitatively tested against\nanalytical predictions and other numerical results. A detailed analysis of\nconvergence to the sharp interface limit is performed for the linear dispersion\nresults. We show that the method may be a useful alternative to more\ntraditional methods."
    },
    {
        "anchor": "Polymer Solutions: The article provides a brief general introduction into the concepts of\nscaling, universality, and crossover scaling, plus the blob concept that\nprovides an intuitive picture of crossover phenomena. We present the most\nimportant static and dynamic scaling laws for unentangled uncharged polymer\nsolutions, together with their test and refinement by careful computer\nsimulations. A hoard of simulation methods has been developed for these\nsystems, and these will be briefly discussed as well.",
        "positive": "Transport coefficients of soft sphere fluids at high densities: Molecular dynamics computer simulation has been used to compute the\nself-diffusion coefficient, and shear viscosity of soft-sphere fluids, in which\nthe particles interact through the soft-sphere or inverse power pair potential.\nThe calculations have been made along the melting line in a wide range of\npressures and temperatures. The validity of scaling relations for thermodynamic\nparameters and kinetic coefficients was checked. It was shown that the\nStokes-Einstein relationship is obeyed if the Barker diameter is used as a\ncharacteristic length scale. It was also shown that the viscosity is\nnon-monotonic along the isochores as predicted by Ya. Rosenfeld. It was shown\nthat the viscosity is strongly growing along the melting line, however, this\nincrease does not stimulate the glass transition because the relaxation time is\ndecreasing."
    },
    {
        "anchor": "Flocking by turning away: Flocking, as paradigmatically exemplified by birds, is the coherent\ncollective motion of active agents. As originally conceived, flocking emerges\nthrough alignment interactions between the agents. Here, we report that\nflocking can also emerge through interactions that turn agents away from each\nother. Combining simulations, kinetic theory, and experiments, we demonstrate\nthis mechanism of flocking in self-propelled Janus colloids with stronger\nrepulsion on the front than on the rear. The polar state is stable because\nparticles achieve a compromise between turning away from left and right\nneighbors. Unlike for alignment interactions, the emergence of polar order from\nturn-away interactions requires particle repulsion. At high concentration,\nrepulsion produces flocking Wigner crystals. Whereas repulsion often leads to\nmotility-induced phase separation of active particles, here it combines with\nturn-away torques to produce flocking. Therefore, our findings bridge the\nclasses of aligning and non-aligning active matter. Our results could help to\nreconcile the observations that cells can flock despite turning away from each\nother via contact inhibition of locomotion. Overall, our work shows that\nflocking is a very robust phenomenon that arises even when the orientational\ninteractions would seem to prevent it.",
        "positive": "The distribution function of a semiflexible polymer and random walks\n  with constraints: In studying the end-to-end distribution function $G(r,N)$ of a worm like\nchain by using the propagator method we have established that the combinatorial\nproblem of counting the paths contributing to $G(r,N)$ can be mapped onto the\nproblem of random walks with constraints, which is closely related to the\nrepresentation theory of the Temperley-Lieb algebra. By using this mapping we\nderive an exact expression of the Fourier-Laplace transform of the distribution\nfunction, $G(k,p)$, as a matrix element of an inverse of an infinite rank\nmatrix. Using this result we also derived a recursion relation permitting to\ncompute $G(k,p)$ directly. We present the results of the computation of\n$G(k,N)$ and its moments. The moments $<r^{2n}>$ of $% G(r,N)$ can be\ncalculated \\emph{exactly} by calculating the (1,1) matrix element of $2n$-th\npower of a truncated matrix of rank $n+1$."
    },
    {
        "anchor": "Model of graphene nanobubble: combining classical density functional and\n  elasticity theories: A graphene nanobubble consists of a graphene sheet, an atomically flat\nsubstrate and a substance enclosed between them. Unlike conventional\nconfinement with rigid walls and a fixed volume, the graphene nanobubble has\none stretchable wall, which is the graphene sheet, and its volume can be\nadjusted by changing the shape. In this study, we developed a model of a\ngraphene nanobubble based on classical density functional theory and the\nelastic theory of membranes. The proposed model takes into account the\ninhomogeneity of the enclosed substance, the nonrigidity of the wall and the\nalternating volume. As an example application, we utilize the developed model\nto investigate fluid argon inside graphene nanobubbles at room temperature. We\nobserved a constant height-to-radius ratio over the whole range of radii\nconsidered, which is in agreement with the results from experiments and\nmolecular dynamics simulations. The developed model provides a theoretical tool\nto study both the inner structure of the confined substance and the shape of\nthe graphene nanobubble. The model can be easily extended to other types of\nnonrigid confinement.",
        "positive": "Universal shape characteristics for the mesoscopic polymer chain via\n  dissipative particle dynamics: In this paper we study the shape characteristics of a polymer chain in a good\nsolvent using a mesoscopic level of modelling. The dissipative particle\ndynamics simulations are performed in the $3D$ space at a range of chain\nlengths $N$. The scaling laws for the end-to-end distance and gyration radius\nare examined first and found to hold for $N\\geq 10$ yielding reasonably\naccurate value for the Flory exponent $\\nu$. Within the same interval of chain\nlengths, the asphericity, prolateness, size ratio and other shape\ncharacteristics of the chain are found to become independent of $N$. Their mean\nvalues are found to agree reasonably well with the respective theoretical\nresults and lattice Monte Carlo simulations. Broad probability distributions\nfor the shape characteristics are found resembling in form the results of\nlattice Monte Carlo simulations. By means of analytic fitting of these\ndistributions the most probable values for the shape characteristics are found\nto supplement their mean values."
    },
    {
        "anchor": "Long-Lived Non-Equilibrium Interstitial-Solid-Solutions in Binary\n  Mixtures: We perform particle resolved experimental studies on the heterogeneous\ncrystallisation process of two compo- nent mixtures of hard spheres. The\ncomponents have a size ratio of 0.39. We compared these with molecular dynamics\nsimulations of homogenous nucleation. We find for both experiments and\nsimulations that the final assemblies are interstitial solid solutions, where\nthe large particles form crystalline close-packed lattices, whereas the small\nparticles occupy random interstitial sites. This interstitial solution\nresembles that found at equilibrium when the size ratios are 0.3 [Filion et\nal., Phys. Rev. Lett. 107, 168302 (2011)] and 0.4 [Filion, PhD Thesis, Utrecht\nUniversity (2011)]. However, unlike these previous studies, for our system sim-\nulations showed that the small particles are trapped in the octahedral holes of\nthe ordered structure formed by the large particles, leading to long-lived\nnon-equilibrium structures in the time scales studied and not the equilibrium\ninterstitial solutions found earlier. Interestingly, the percentage of small\nparticles in the crystal formed by the large ones rapidly reaches a maximum of\naround 14% for most of the packing fractions tested, unlike previous\npredictions where the occupancy of the interstitial sites increases with the\nsystem concentration. Finally, no further hopping of the small particles was\nobserved.",
        "positive": "Influence of Rough and Smooth Walls on Macroscale Flows in Tumblers: Walls in discrete element method simulations of granular flows are sometimes\nmodeled as a closely packed monolayer of fixed particles, resulting in a rough\nwall rather than a geometrically smooth wall. An implicit assumption is that\nthe resulting rough wall differs from a smooth wall only locally at the\nparticle scale. Here we test this assumption by considering the impact of the\nwall roughness at the periphery of the flowing layer on the flow of\nmonodisperse particles in a rotating spherical tumbler. We find that varying\nthe wall roughness significantly alters average particle trajectories even far\nfrom the wall. Rough walls induce greater poleward axial drift of particles\nnear the flowing layer surface, but decrease the curvature of the trajectories.\nIncreasing the volume fill level in the tumbler has little effect on the axial\ndrift for rough walls, but increases the drift while reducing curvature of the\nparticle trajectories for smooth walls. The mechanism for these effects is\nrelated to the degree of local slip at the bounding wall, which alters the\nflowing layer thickness near the walls, affecting the particle trajectories\neven far from the walls near the equator of the tumbler. Thus, the proper\nchoice of wall conditions is important in the accurate simulation of granular\nflows, even far from the bounding wall."
    },
    {
        "anchor": "Experimental evidence of ageing and slow restoration of the weak-contact\n  configuration in tilted 3D granular packings: Granular packings slowly driven towards their instability threshold are\nstudied using a digital imaging technique as well as a nonlinear acoustic\nmethod. The former method allows us to study grain rearrangements on the\nsurface during the tilting and the latter enables to selectively probe the\nmodifications of the weak-contact fraction in the material bulk. Gradual ageing\nof both the surface activity and the weak-contact reconfigurations is observed\nas a result of repeated tilt cycles up to a given angle smaller than the angle\nof avalanche. For an aged configuration reached after several consecutive tilt\ncycles, abrupt resumption of the on-surface activity and of the weak-contact\nrearrangements occurs when the packing is subsequently inclined beyond the\nprevious maximal tilting angle. This behavior is compared with literature\nresults from numerical simulations of inclined 2D packings. It is also found\nthat the aged weak-contact configurations exhibit spontaneous restoration\ntowards the initial state if the packing remains at rest for tens of minutes.\nWhen the packing is titled forth and back between zero and near-critical\nangles, instead of ageing, the weak-contact configuration exhibits \"internal\nweak-contact avalanches\" in the vicinity of both the near-critical and zero\nangles. By contrast, the stronger-contact skeleton remains stable.",
        "positive": "Out-of-equilibrium microrheology using optical tweezers to probe\n  directional viscoelastic properties under shear: Many wormlike micellar systems exhibit appreciable shear thinning due to\nshear induced alignment. As the micelles get aligned introducing directionality\nin the system, the viscoelastic properties are no longer expected to be\nisotropic. An optical tweezers based active microrheology technique enables us\nto probe the out-of-equilibrium rheological properties of a wormlike micellar\nsystem simultaneously along two orthogonal directions - parallel to the applied\nshear, as well as perpendicular to it. While the displacements of a trapped\nbead - in response to active drag force carry signature of conventional shear\nthinning, its spontaneous position fluctuations along the perpendicular\ndirection manifest an orthogonal shear thickening, an effect hitherto\nunobserved."
    },
    {
        "anchor": "Equilibrium configurations of hard spheres in a cylindrical harmonic\n  potential: A line of hard spheres confined by a transverse harmonic potential, with hard\nwalls at its ends, exhibits a variety of buckled structures as it is compressed\nlongitudinally. Here we show that these may be conveniently observed in a\nrotating liquid-filled tube (originally introduced by Lee et al. [T. Lee, K.\nGizynski, and B. Grzybowski, Adv. Mater. 29, 1704274 (2017)] to assemble\nordered three dimensional structures at higher compressions). The corresponding\ntheoretical model is transparent and easily investigated numerically, as well\nas by analytic approximations. Hence we explore a wide range of predicted\nstructures occurring via bifurcation, of which the stable ones are also\nobserved in our experiments. Qualitatively similar structures have previously\nbeen found in trapped ion systems.",
        "positive": "Swelling of asymmetric pom-pom polymers in dilute solutions: In this paper we continue our recent analysis [K. Haydukivska et al., J. Mol.\nLiq., 2021, 328, 115456] of complex molecules with two branching points at both\nends of the linear backbone with $f_1$ and $f_2$ side arms starting from them,\nknown as the pom-pom polymers. Here, we analyze the asymmetric case, $f_1 \\neq\nf_2$, by applying both the analytical approach, based on the direct polymer\nrenormalization, and computer simulations using both dissipative particle\ndynamics and Monte Carlo methods. We study the role played by the molecular\nasymmetry of average polymer conformations, considering the infinite dilution\nregime and good solvent conditions.The quantitative estimates are reported for\nthe set of universal size and shape characteristics of such molecules and for\ntheir individual branches, all the functions of $f_1$ and $f_2$. In particular,\nwe evaluate the size ratio of the gyration radii of symmetric and asymmetric\npom-pom topologies with the same molecular weight and quantitatively reveal an\nincrease of the effective size of a molecule caused by its asymmetry. We also\nintroduce and analyse the asymmetry factor and estimate the shift of the center\nof mass caused by the presence of side stars, which can serve as another\ncharacteristic of the asymmetry of pom-pom structure."
    },
    {
        "anchor": "Unified physical framework for stretched-exponential,\n  compressed-exponential, and logarithmic relaxation phenomena in glassy\n  polymers: We develop a simple yet comprehensive nonlinear model to describe relaxation\nphenomena in amorphous glass-formers near the glass transition temperature. The\nmodel is based on the two-state, two-(time)scale (TS2) framework, and describes\nthe isothermal relaxation of specific volume, enthalpy, or shear stress via a\nsimple first-order nonlinear differential equation (the Trachenko-Zaccone [TZ]\nequation) for local cooperative events. These nonlinear dynamics of\ncooperatively rearranging regions (CRR) naturally arise from the TS2 framework.\nWe demonstrate that the solutions of the TZ equation comprehensively encompass\nthe Debye exponential relaxation, the Kohlrausch-Williams-Watts (KWW) stretched\nand compressed relaxations, and the Guiu-Pratt logarithmic relaxation.\nFurthermore, for the case of stress relaxation modeling, our model recovers, as\none of its limits, the Eyring law for plastic flow, where the Eyring activation\nvolume is related to thermodynamic parameters of the material. Using the\nexample of polystyrene (PS), we demonstrate how our model successfully\ndescribes the Kovacs \"asymmetry of approach\" specific volume and enthalpy\nexperiments, as well as the stress relaxation. Other potential applications of\nthe model, including the dielectric relaxation, are also discussed. The\npresented approach disentangles the physical origins of different relaxation\nlaws within a single general framework based on the underlying physics.",
        "positive": "Collective drifts in vibrated granular packings: the interplay of\n  friction and structure: We simulate vertically shaken dense granular packings with horizontal\nperiodic boundary conditions. A coordinated translating motion of the whole\nmedium emerges when the horizontal symmetry is broken by disorder or defects in\nthe packing and the shaking is weak enough to conserve the structure. We argue\nthat such a drift originates in the interplay between structural symmetry\nbreaking and frictional forces transmitted by the vibrating plate. A non-linear\nratchet model with stick-slips reproduces many faces of the phenomenon. The\ncollective motion discussed here underlies phenomena observed recently with\nvibrofluidized granular materials, such as persistent rotations and anomalous\ndiffusion."
    },
    {
        "anchor": "Compatibility between shape equation and boundary conditions of lipid\n  membranes with free edges: Only some special open surfaces satisfying the shape equation of lipid\nmembranes can be compatible with the boundary conditions. As a result of this\ncompatibility, the first integral of the shape equation should vanish for\naxisymmetric lipid membranes, from which two theorems of non-existence are\nverified: (i) There is no axisymmetric open membrane being a part of torus\nsatisfying the shape equation; (ii) There is no axisymmetric open membrane\nbeing a part of a biconcave discodal surface satisfying the shape equation.\nAdditionally, the shape equation is reduced to a second-order differential\nequation while the boundary conditions are reduced to two equations due to this\ncompatibility. Numerical solutions to the reduced shape equation and boundary\nconditions agree well with the experimental data [A. Saitoh \\emph{et al.},\nProc. Natl. Acad. Sci. USA \\textbf{95}, 1026 (1998)].",
        "positive": "Microscopic Description of Entanglements in Polyethylene Networks and\n  Melts: Strong, Weak, Pairwise, and Collective Attributes: We present atomistic molecular dynamics simulations of two Polyethylene\nsystems where all entanglements are trapped: a perfect network, and a melt with\ngrafted chain ends. We examine microscopically at what level topological\nconstraints can be considered as a collective entanglement effect, as in tube\nmodel theories, or as certain pairwise uncrossability interactions, as in\nslip-link models. A pairwise parameter, which varies between these limiting\ncases, shows that, for the systems studied, the character of the entanglement\nenvironment is more pairwise than collective.\n  We employ a novel methodology, which analyzes entanglement constraints into a\ncomplete set of pairwise interactions, similar to slip links. Entanglement\nconfinement is assembled by a plethora of links, with a spectrum of confinement\nstrengths, from strong to weak. The strength of interactions is quantified\nthrough a link `persistence', which is the fraction of time for which the links\nare active. By weighting links according to their strength, we show that\nconfinement is imposed mainly by the strong ones, and that the weak, trapped,\nuncrossability interactions cannot contribute to the low frequency modulus of\nan elastomer, or the plateau modulus of a melt.\n  A self-consistent scheme for mapping topological constraints to specific,\nstrong binary links, according to a given entanglement density, is proposed and\nvalidated. Our results demonstrate that slip links can be viewed as the\nstrongest pairwise interactions of a collective entanglement environment. The\nmethodology developed provides a basis for bridging the gap between atomistic\nsimulations and mesoscopic slip link models."
    },
    {
        "anchor": "Event-chain Monte Carlo: foundations, applications, and prospects: This review treats the mathematical and algorithmic foundations of\nnon-reversible Markov chains in the context of event-chain Monte Carlo (ECMC),\na continuous-time lifted Markov chain that employs the factorized Metropolis\nalgorithm. It analyzes a number of model applications, and then reviews the\nformulation as well as the performance of ECMC in key models in statistical\nphysics. Finally, the review reports on an ongoing initiative to apply the\nmethod to the sampling problem in molecular simulation, that is, to real-world\nmodels of peptides, proteins, and polymers in aqueous solution.",
        "positive": "A plate theory for nematic liquid crystalline solids: We derive a F\\\"{o}ppl-von K\\'{a}rm\\'{a}n-type constitutive model for solid\nliquid crystalline plates where the nematic director may or may not rotate\nfreely relative to the elastic network. To obtain the reduced two-dimensional\nmodel, we rely on the deformation decomposition of a nematic solid into an\nelastic deformation and a natural shape change. The full solution to the\nresulting equilibrium equations consists of both the deformation displacement\nand stress fields. The model equations are applicable to a wide range of thin\nnematic bodies subject to optothermal stimuli and mechanical loads. For\nillustration, we consider certain reversible natural shape changes in simple\nsystems which are stress free, and their counterparts, where the natural\ndeformations are blocked and internal stresses appear. More general problems\ncan be addressed within the same framework."
    },
    {
        "anchor": "How the overlap of excluded volume determines the configurational energy\n  landscape and \"thermodynamics\" in the \"one to five hard disks in a box\"\n  system: In this work, the effects of excluded volume are studied in the \"one to five\nhard disks in a box\" system. For one and two disks in different types of cages,\nthe attractive and repulsive forces are calculated analytically. Attractive\nforces are due to excluded volume overlap, and thus allows to understand that\nin hard-core systems, second neighbors have an effective interaction, a fact\nthat is usually neglected when considering only collisions with\nfirst-neighbors. The same effects are observed for numerical computations with\nfive-disks in a box, as the distributions of distances between disks and disks\nto walls suggest. The results indicate that first and second-neighbor excluded\nvolume interactions are essential to determine the energy landscape topology.\nThis work supports previous observations that suggests that second-neighbor\nexcluded volume interactions in hard-core systems are related with phase\ntransitions.",
        "positive": "The Mnemosyne Number and the Rheology of Remembrance: The concept of a Deborah number is widely used in study of viscoelastic\nmaterials and to represent the ratio of a material relaxation time to the\ntimescale of observation, and to demarcate transitions between predominantly\nviscous or elastic material responses. However, this construct does not help\nquantify the importance of long transients and non-monotonic stress jumps that\nare often observed in more complex time-varying systems. Many of these\nnon-intuitive effects are lumped collectively under the term thixotropy;\nhowever, no proper nouns are associated with the key phenomena observed in such\nmaterials. Thixotropy arises from the ability of a complex structured fluid to\nremember its prior deformation history, so it is natural to name the\ndimensionless group representing such behavior with respect to the ability to\nremember. In Greek mythology, Mnemosyne was mother of the nine Muses and the\ngoddess of memory. We thus propose the definition of a Mnemosyne number as the\ndimensionless product of the thixotropic time scale and the imposed rate of\ndeformation. The Mnemosyne number is thus a measure of the flow strength\ncompared to the thixotropic timescale. Since long transients responses are\nendemic to thixotropic materials, one also needs to consider the duration of\nflow. The relevant dimensionless measure of this duration can be represented in\nterms of a mutation number which compares the timescale of\nexperiment/observation to the thixotropic timescale. Collating the mutation\nnumber and the Mnemosyne number, we construct a general two-dimensional map of\nthixotropic behavior, and quantify these ideas using canonical thixotropic\nmodels."
    },
    {
        "anchor": "Towards a general definition of gelation for adhesive hard-sphere\n  dispersions: One major goal in condensed matter physics is identifying the physical\nmechanisms that lead to arrested states of matter, especially gels and glasses.\nThe complex nature and microscopic details of each particular system are\nrelevant. However, from both scientific and technological viewpoints, a\ngeneral, consistent and unified definition is of paramount importance. Through\nMonte Carlo computer simulations of states identified in experiments, we\ndemonstrate that adhesive hard-sphere dispersions are the result of rigidity\npercolation with average number of bonds, $<n_b>$, equals to 2.4. This\ncorresponds to an established mechanism leading to phase transitions in\nnetwork-forming materials. Our findings connect the concept of critical gel\nformation in colloidal suspensions with short-range attractive interactions to\nthe universal concept of rigidity percolation. Furthermore, the bond, angular\nand local distributions along the gelation line are explicitly studied in order\nto determine the topology of the structure of the critical gel state.",
        "positive": "Transport properties of Lennard-Jones fluids: Freezing density scaling\n  along isotherms: It is demonstrated that properly reduced transport coefficients\n(self-diffusion, shear viscosity, and thermal conductivity) of Lennard-Jones\nfluids along isotherms exhibit quasi-universal scaling on the density divided\nby its value at the freezing point. Moreover, this scaling is closely related\nto the density scaling of transport coefficients of hard-sphere fluids. The\nStokes-Einstein relation without the hydrodynamic diameter is valid in the\ndense fluid regime. The lower density boundary of its validity can serve as a\npractical demarcation line between gas-like and liquid-like regimes."
    },
    {
        "anchor": "Experimental verification of democratic particle motions by direct\n  imaging of glassy colloidal systems: We analyze data from confocal microscopy experiments of a colloidal\nsuspension to validate predictions of rapid sporadic events responsible for\nstructural relaxation in a glassy sample. The trajectories of several thousand\ncolloidal particles are analyzed, confirming the existence of rapid sporadic\nevents responsible for the structural relaxation of significant regions of the\nsample, and complementing prior observations of dynamical heterogeneity. The\nemergence of relatively compact clusters of mobility allows the dynamics to\ntransition between the large periods of local confinement within its potential\nenergy surface, in good agreement with the picture envisioned long ago by Adam\nand Gibbs and Goldstein.",
        "positive": "Dynamic Transitions in a Two Dimensional Associating Lattice Gas Model: Using Monte Carlo simulations we investigate some new aspects of the phase\ndiagram and the behavior of the diffusion coefficient in an associating lattice\ngas (ALG) model on different regions of the phase diagram. The ALG model\ncombines a two dimensional lattice gas where particles interact through a soft\ncore potential and orientational degrees of freedom. The competition between\nsoft core potential and directional attractive forces results in a high density\nliquid phase, a low density liquid phase, and a gas phase. Besides anomalies in\nthe behavior of the density with the temperature at constant pressure and of\nthe diffusion coefficient with density at constant temperature are also found.\nThe two liquid phases are separated by a coexistence line that ends in a\nbicritical point. The low density liquid phase is separated from the gas phase\nby a coexistence line that ends in tricritical point. The bicritical and\ntricritical points are linked by a critical $\\lambda$-line. The high density\nliquid phase and the fluid phases are separated by a second $\\tau$ critical\nline. We then investigate how the diffusion coefficient behaves on different\nregions of the chemical potential-temperature phase diagram. We find that\ndiffusivity undergoes two types of dynamic transitions: a fragile-to-strong\ntrans ition when the critical $\\lambda$-line is crossed by decreasing the\ntemperature at a constant chemical potential; and a strong-to-strong transition\nwhen the $\\tau$-critical line is crossed by decreasing the temperature at a\nconstant chemical potential."
    },
    {
        "anchor": "Elastohydrodynamics of swimming helices: effects of flexibility and\n  confinement: Motivated by bacterial transport through porous media, here we study the\nswimming of an actuated, flexible helical filament in both three-dimensional\nfree space and within a cylindrical tube whose diameter is much smaller than\nthe length of the helix. The filament, at rest, has a native helical shape\nmodeled after the geometry of a typical bacterial flagellar bundle. The finite\nlength filament is a free swimmer, and is driven by an applied torque as well\nas a counter-torque (of equal strength and opposite direction) that represents\na virtual cell body. We use a regularized Stokeslet framework to examine the\nshape changes of the flexible filament in response to the actuation as well as\nthe swimming performance as a function of the nondimensional Sperm number that\ncharacterizes the elastohydrodynamic system. We also show that a modified Sperm\nnumber may be defined to characterize the swimming progression within a tube.\nFinally, we demonstrate that a helical filament whose axis is not aligned with\nthe tube axis can exhibit centering behavior in the narrowest tubes.",
        "positive": "Emergent smectic order in simple active particle models: Novel \"smectic-P\" behavior, in which self-propelled particles form rows and\nmove on average along them, occurs generically within the\norientationally-ordered phase of simple models that we simulate. Both apolar\n(head-tail symmetric) and polar (head-tail asymmetric) models with aligning and\nrepulsive interactions exhibit slow algebraic decay of smectic order with\nsystem size up to some finite length scale, after which faster decay occurs. In\nthe apolar case, this scale is that of an undulation instability of the rows.\nIn the polar case, this instability is absent, but traveling fluctuations\ndisrupt the rows in large systems and motion and smectic order may\nspontaneously globally rotate. These observations agree with a new hydrodynamic\ntheory which we present here. Variants of our models also exhibit active\nsmectic \"A\" and \"C\" order, with motion orthogonal and oblique to the layers\nrespectively."
    },
    {
        "anchor": "Defect structures and torque on an elongated colloidal particle immersed\n  in a liquid crystal host: Combining molecular dynamics and Monte Carlo simulation we study defect\nstructures around an elongated colloidal particle embedded in a nematic liquid\ncrystal host. By studying nematic ordering near the particle and the\ndisclination core region we are able to examine the defect core structure and\nthe difference between two simulation techniques. In addition, we also study\nthe torque on a particle tilted with respect to the director, and modification\nof this torque when the particle is close to the cell wall.",
        "positive": "Determine the strength of soft bonds: The strength of a simple soft bond under constant loading rate is studied\ntheoretically. We find a scaling regime where rebinding is negligible and the\nrupture force of the bond scales as $const. + (\\ln (kv))^{2/3}$, where $kv$ is\nthe loading rate. The scaling regime is smaller for weaker bonds and broader\nfor stronger bonds. For loading rate beyond the upper limit of the scaling\nregime, bond rupture is deterministic and thermal effects are negligible. For\nloading rate below the lower limit of the scaling regime, contribution from\nrebinding becomes important, and there is no simple scaling relation between\nrupture force and loading rate. When we extend the theory to include the effect\nof rebinding we find good agreement between theory and simulation even below\nthe scaling regime."
    },
    {
        "anchor": "Water affects morphogenesis of growing aquatic plant leaves: Lotus leaves floating on water usually experience short-wavelength edge\nwrinkling that decays toward the center, while the leaves growing above water\nnormally morph into a global bending cone shape with long rippled waves near\nthe edge. Observations suggest that the underlying water (liquid substrate)\nsignificantly affects the morphogenesis of leaves. To understand the\nbiophysical mechanism under such phenomena, we develop mathematical models that\ncan effectively account for inhomogeneous differential growth of floating and\nfree-standing leaves, to quantitatively predict formation and evolution of\ntheir morphology. We find, both theoretically and experimentally, that the\nshort-wavelength buckled configuration is energetically favorable for growing\nmembranes lying on liquid, while the global buckling shape is more preferable\nfor suspended ones. Other influencing factors such as stem/vein, heterogeneity\nand dimension are also investigated. Our results provide a fundamental insight\ninto a variety of plant morphogenesis affected by water foundation and suggest\nthat such surface instabilities can be harnessed for morphology control of\nbiomimetic deployable structures using substrate or edge actuation.",
        "positive": "Dense packing crystal structures of physical tetrahedra: We present a method for discovering dense packings of general convex hard\nparticles and apply it to study the dense packing behavior of a one-parameter\nfamily of particles with tetrahedral symmetry representing a deformation of the\nideal mathematical tetrahedron into a less ideal, physical, tetrahedron and all\nthe way to the sphere. Thus, we also connect the two well studied problems of\nsphere packing and tetrahedron packing on a single axis. Our numerical results\nuncover a rich optimal-packing behavior, compared to that of other continuous\nfamilies of particles previously studied. We present four structures as\ncandidates for the optimal packing at different values of the parameter,\nproviding an atlas of crystal structures which might be observed in systems of\nnano-particles with tetrahedral symmetry."
    },
    {
        "anchor": "Polymers as compressible soft spheres: We consider a coarse-grained model in which polymers under good-solvent\nconditions are represented by soft spheres whose radii, which should be\nidentified with the polymer radii of gyrations, are allowed to fluctuate. The\ncorresponding pair potential depends on the sphere radii. This model is a\nsingle-sphere version of the one proposed in Vettorel et al., Soft Matter 6,\n2282 (2010), and it is sufficiently simple to allow us to determine all\npotentials accurately from full-monomer simulations of two isolated polymers\n(zero-density potentials). We find that in the dilute regime (which is the\nexpected validity range of single-sphere coarse-grained models based on\nzero-density potentials) this model correctly reproduces the density dependence\nof the radius of gyration. However, for the thermodynamics and the\nintermolecular structure, the model is largely equivalent to the simpler one in\nwhich the sphere radii are fixed to the average value of the radius of gyration\nand radiiindependent potentials are used: for the thermodynamics there is no\nadvantage in considering a fluctuating sphere size.",
        "positive": "Electrostatic correlations: from Plasma to Biology: Electrostatic correlations play an important role in physics, chemistry and\nbiology. In plasmas they lead to thermodynamic instability similar to the\nliquid-gas phase transition of simple molecular fluids. For charged colloidal\nsuspensions the electrostatic correlations are responsible for screening and\ncolloidal charge renormalization. In aqueous solutions containing multivalent\ncounterions they can lead to charge inversion and flocculation. In biological\nsystems the correlations account for the organization of cytoskeleton and the\ncompaction of genetic material. In spite of their ubiquity, the true importance\nof electrostatic correlations has become fully appreciated only quite recently.\nIn this paper, I will review the thermodynamic consequences of electrostatic\ncorrelations in a variety of systems ranging from classical plasmas to\nmolecular biology."
    },
    {
        "anchor": "Self-Polarizing Microswimmers in Active Density Waves: An artificial microswimmer drifts in response to spatio-temporal modulations\nof an activating suspension medium. We consider two competing mechanisms\ncapable of influencing its tactic response: angular fluctuations, which help it\nexplore its surroundings and thus diffuse faster toward more active regions,\nand self-polarization, a mechanism inherent to self-propulsion, which tends to\norient the swimmer's velocity parallel or antiparallel to the local activation\ngradients. We investigate, both numerically and analytically, the combined\naction of such two mechanisms. By determining their relative magnitude, we\ncharacterize the selective transport of artificial microswimmers in\ninhomogeneous activating media.",
        "positive": "Distinct signature of two local structural motifs of liquid water in the\n  scattering function: Liquids generally become more ordered upon cooling. However, it has been a\nlong-standing debate on whether such structural ordering in liquid water takes\nplace continuously or discontinuosly: continuum vs. mixture models. Here, by\ncomputer simulations of three popular water models and analysis of recent\nscattering experiment data, we show that, in the structure factor of water,\nthere are two overlapped peaks hidden in the apparent \"first diffraction peak\",\none of which corresponds to the neighboring O-O distance as in ordinary liquids\nand the other to the longest periodicity of density waves in a tetrahedral\nstructure. This unambiguously proves the coexistence of two local structural\nmotifs. Our findings not only provide key clues to settle long-standing\ncontroversy on the water structure but also allow experimental access to the\ndegree and range of structural ordering in liquid water."
    },
    {
        "anchor": "An external potential dynamic study on the formation of interface in\n  polydisperse polymer blends: The formation of interface from an initial sharp interface in polydisperse\nA/B blends is studied using the external potential dynamic method. The present\nmodel is a nonlocal coupling model as we take into account the correlation\nbetween segments in a single chain. The correlation is approximately expressed\nby Debye function and the diffusion dynamics are based on the Rouse chain\nmodel. The chain length distribution is described by the continuous Schulz\ndistribution. Our numerical calculation indicates that the broadening of\ninterface with respect to time obeys a power law at early times, and the power\nlaw indexes are the same for both monodisperse and polydisperse blend. The\npower law index is larger than that in the local coupling model. However there\nis not a unified scaling form of the broadening of the interface width if only\nthe interfacial width at equilibrium is taken into account as the\ncharacteristic length of the system, because the correlation makes an extra\ncharacteristic length in the system, and the polydispersity is related to this\nlength.",
        "positive": "A Mean Field Model of Layering Instability in Shearing Suspensions: Concentrated suspensions may shear-thin when the suspended particles form\nplanar sheets that slide over one another with less friction than if the\nparticles are randomly distributed. In a na\\\"ive model the suspension is\ndescribed by a mean effective viscosity, and particles that collide with each\nother redistribute the mean density in the shearing direction. This leads to a\ndiffusion equation for the particle density. If the viscosity in the unthinned\nstate is a steeply increasing function of particle density the effective\ndiffusion coefficient is negative and the diffusion equation, meaningful only\non scales larger than the particle separation, is ill-posed. This singularity\ncorresponds to the formation of planar sheets of particles and defines a\ncritical particle density for the onset of shear thinning."
    },
    {
        "anchor": "A theory of magneto-elastic nanorods obtained through rigorous dimension\n  reduction: Starting from a two-dimensional theory of magneto-elasticity for\nfiber-reinforced magnetic elastomers we carry out a rigorous dimension\nreduction to derive a rod model that describes a thin magneto-elastic strip\nundergoing planar deformations. The main features of the theory are the\nfollowing: a magneto-elastic interaction energy that manifests itself through a\ndistributed torque; a penalization term that prevent local interpenetration of\nmatter; a regularization that depends on the second gradient of the deformation\nand models microstructure-induced size effects. As an application, we study a\nproblem involving magnetically-induced buckling and we show that the intensity\nof the field at the onset of the instability increases if the length of the rod\nis decreased. Finally, we assess the accuracy of the deduced model by\nperforming numerical simulations where we compare the two-dimensional and the\none-dimensional theory in some special cases and we observe excellent\nagreement.",
        "positive": "Phase separation of self-propelled disks with ferromagnetic and nematic\n  alignment: We present a comprehensive study of a model system of repulsive\nself-propelled disks in two dimensions with ferromagnetic and nematic velocity\nalignment interactions. We characterize the phase behavior of the system as a\nfunction of the alignment and self-propulsion strength, featuring orientational\norder for strong alignment and Motility-Induced Phase Separation (MIPS) at\nmoderate alignment but high enough self-propulsion. We derive a microscopic\ntheory for these systems yielding a close set of hydrodynamic equations from\nwhich we perform a linear stability analysis of the homogenous disordered\nstate. This analysis predicts MIPS in the presence of aligning torques. The\nnature of the continuum theory allows for an explicit quantitative comparison\nwith particle-based simulations, which consistently shows that ferromagnetic\nalignment fosters phase separation, while nematic alignment does not alter\neither the nature or the location of the instability responsible for it. In the\nferromagnetic case, such behavior is due to an increase of the imbalance of the\nnumber of particle collisions along different orientations, giving rise to the\nself-trapping of particles along their self-propulsion direction. On the\ncontrary, the anisotropy of the pair correlation function, which encodes this\nself-trapping effect, is not significantly affected by nematic torques. Our\nwork shows the predictive power of such microscopic theories to describe\ncomplex active matter systems with different interaction symmetries and sheds\nlight on the impact of velocity-alignment interactions in Motility-Induced\nPhase Separation."
    },
    {
        "anchor": "Active pulsatile gels: from chemical microreactor to polymeric actuator: We report on a synthesis protocol, experimental characterization and\ntheoretical modeling of active pulsatile Belousov-Zhabotinsky (BZ) hydrogels.\nOur two-step synthesis technique allows independent optimization of the\ngeometry, the chemical, and the mechanical properties of BZ gels. We identify\nthe role of the surrounding medium chemistry and gel radius for the occurrence\nof BZ gel oscillations, quantified by the Damkohler number, ratio of chemical\nreaction to diffusion rates. Tuning the BZ gel size to maximize its\nchemomechanical oscillation amplitude, we find that its oscillatory strain\namplitude is limited by the timescale of gel swelling relative to the chemical\noscillation period. Our experimental findings are in good agreement with a\nVanag-Epstein model of BZ chemistry and a Tanaka Fillmore theory of gel\nswelling dynamics.",
        "positive": "Effect of rigid top surface on the onset of phototactic bioconvection: Phototaxis is the movement of microorganisms towards or away from light. In\npresence of dim (intense) light, microorganisms move towards (away from) the\nlight sources, which is known as positive (negative) phototaxis. In this study,\nwe present a model in which isotropic scattering algae suspension is\nilluminated by both diffuse and collimated irradiation, and the top surface is\nassumed to be rigid. Bimodal steady states result from the scattering Effect\n(for almost purely scattering suspension), which transits into a unimodal\nsteady state as diffuse light intensity increases. The linear stability of the\nsame suspension is also examined using the linear perturbation theory, which\npredicts the solutions' stable and oscillatory nature for specific parameter\nvalues. Here, we also observe that suspension becomes more stable in a rigid\ntop surface and diffuse irradiation."
    },
    {
        "anchor": "Multiphase imaging of freezing particle suspensions by confocal\n  microscopy: Ice-templating is a well-established processing route for porous ceramics.\nBecause of the structure/properties relationships, it is essential to better\nunderstand and control the solidification microstructures. Ice-templating is\nbased on the segregation and concentration of particles by growing ice\ncrystals. What we understand so far of the process is based on either\nobservations by optical or X-ray imaging techniques, or on the characterization\nof ice-templated materials. However, in situ observations at particle-scale are\nstill missing. Here we show that confocal microscopy can provide multiphase\nimaging of ice growth and the segregation and organization of particles. We\nillustrate the benefits of our approach with the observation of particles and\npore ice in the frozen structure, the dynamic evolution of the freeze front\nmorphology, and the impact of PVA addition on the solidification\nmicrostructures. These results prove in particular the importance of\ncontrolling both the temperature gradient and the growth rate during\nice-templating.",
        "positive": "Chiral liquid crystal colloids: Colloidal particles disturb the alignment of rod-like molecules of liquid\ncrystals, giving rise to long-range interactions that minimize the free energy\nof distorted regions. Particle shape and topology are known to guide this\nself-assembly process. However, how chirality of colloidal inclusions affects\nthese long-range interactions is unclear. Here we study the effects of\ndistortions caused by chiral springs and helices on the colloidal\nself-organization in a nematic liquid crystal using laser tweezers, particle\ntracking and optical imaging. We show that chirality of colloidal particles\ninteracts with the nematic elasticity to predefine chiral or racemic colloidal\nsuperstructures in nematic colloids. These findings are consistent with\nnumerical modelling based on the minimization of Landau-de Gennes free energy.\nOur study uncovers the role of chirality in defining the mesoscopic order of\nliquid crystal colloids, suggesting that this feature may be a potential tool\nto modulate the global orientated self-organization of these systems."
    },
    {
        "anchor": "Nucleation of the crystalline phase of proteins in the presence of\n  semidilute non-adsorbing polymer: Starting from a protein solution which is metastable with respect to the\ncrystalline phase, the effect of adding semidilute non-adsorbing polymer is\nconsidered. It is found to increase the chemical potential of the protein by a\nfew tenths of kT, which may be enough to lower the barrier to nucleation of the\ncrystalline phase by enough to allow crystallisation. It is also shown that\nassuming that the polymer induces a pairwise additive attraction leads to\nqualitatively incorrect results.",
        "positive": "Designing metainterfaces with specified friction laws: Many devices, including touchscreens and robotic hands, involve frictional\ncontacts. Optimizing these devices requires fine control of the interface's\nfriction law. We lack systematic methods to create dry contact interfaces whose\nfrictional behavior satisfies preset specifications. We propose a generic\nsurface design strategy to prepare dry rough interfaces that have predefined\nrelationships between normal and friction forces. Such metainterfaces\ncircumvent the usual multiscale challenge of tribology by considering\nsimplified surface topographies as assemblies of spherical asperities.\nOptimizing the individual asperities' heights enables specific friction laws to\nbe targeted. Through various centimeter-scaled elastomer-glass metainterfaces,\nwe illustrate three types of achievable friction laws, including linear laws\nwith a specified friction coefficient and unusual nonlinear laws. This design\nstrategy represents a scale- and material-independent, chemical-free pathway\ntoward energy-saving and adaptable smart interfaces."
    },
    {
        "anchor": "An index-resolved fixed-point homotopy and potential energy landscapes: Stationary points (SPs) of the potential energy landscapes can be classified\nby their Morse index, i.e., the number of negative eigenvalues of the Hessian\nevaluated at the SPs. In understanding chemical clusters through their\npotential energy landscapes, only SPs of a particular Morse index are needed.\nWe propose a modification of the \"fixed-point homotopy\" method which can be\nused to directly target stationary points of a specified Morse index. We\ndemonstrate the effectiveness of our approach by applying it to the\nLennard-Jones clusters.",
        "positive": "Faceted wrinkling by contracting a curved boundary: Single-mode deformations of two-dimensional materials, such as the Miura-ori\nzig-zag fold, are important to the design of deployable structures because of\ntheir robustness; these usually require careful pre-patterning of the material.\nHere we show that inward contraction of a curved boundary produces a fine\nwrinkle pattern with a novel structure that suggests similar single-mode\ncharacteristics, but with minimal pre-patterning. Using finite-element\nrepresentation of the contraction of a thin circular annular sheet, we show\nthat these sheets wrinkle into a structure well approximated by an isometric\nstructure composed of conical sectors and flat, triangular facets. Isometry\nfavours the restriction of such deformations to a robust low-bending energy\nchannel that avoids stretching. This class of buckling offers a novel way to\nmanipulate sheet morphology via boundary forces."
    },
    {
        "anchor": "Correlation lengths in hydrodynamic models of active nematics: We examine the scaling with activity of the emergent length scales that\ncontrol the nonequilibrium dynamics of an active nematic liquid crystal, using\ntwo popular hydrodynamic models that have been employed in previous studies. In\nboth models we find that the chaotic spatio-temporal dynamics in the regime of\nfully developed active turbulence is controlled by a single active scale\ndetermined by the balance of active and elastic stresses, regardless of whether\nthe active stress is extensile or contractile in nature. The observed scaling\nof the kinetic energy and enstropy with activity is consistent with our\nsingle-length scale argument and simple dimensional analysis. Our results\nprovide a unified understanding of apparent discrepancies in the previous\nliterature and demonstrate that the essential physics is robust to the choice\nof model.",
        "positive": "Monte Carlo simulations of copolymers at homopolymer interfaces:\n  Interfacial structure as a function of the copolymer density: By means of extensive Monte Carlo simulations of the bond fluctuation model,\nwe study the effect of adding AB diblock copolymers on the properties of an\ninterface between demixed homopolymer phases. The parameters are chosen such\nthat the homopolymers are strongly segregated, and the whole range of copolymer\nconcentrations in the two phase coexistence region is scanned. We compare the\n``mushroom'' regime, in which copolymers are diluted and do not interact with\neach other, with the ``wet brush'' regime, where copolymers overlap and\nstretch, but are still swollen by the homopolymers. A ``dry brush'' regime is\nnever entered for our choice of chain lengths. ``Intrinsic'' profiles are\ncalculated using a block analysis method introduced by us in earlier work. We\ndiscuss density profiles, orientational profiles and contact number profiles.\nIn general, the features of the profiles are similar at all copolymer\nconcentrations, however, the profiles in the concentrated regime are much\nbroader than in the dilute regime. The results compare well with\nself-consistent field calculations."
    },
    {
        "anchor": "Statistical mechanics of elastica for the shape of supercoiled DNA:\n  hyperelliptic elastica of genus three: This article studies the statistical mechanics of elastica as a model of the\nshapes of the supercoiled DNA, and shows that its excited states can be\ncharacterized by the focusing modified KdV (MKdV) equation due to thermal\nfluctuation. Following the previous paper (Matsutani and Previato, Physica D\n430 (2022) 133073), the hyperelliptic solutions of the focusing modified KdV\n(MKdV) equation of genus three are considered. There appears a pattern as a\nrepetition of the modulation of figure-eight and the inverse 'S' as a thermal\nfluctuation of elastica, called the S-eight mode. Our model states that the\nexcited states of elastica due to the thermal effect have the S-eight mode,\nwhich reproduces the shapes of the AFM image of the supercoiled DNAs observed\nby Japaridze et al. (Nano Lett. 17 3, (2017) 1938).",
        "positive": "Colloids electrophoresis for strong and weak ion diffusivity: We study the electrophoretic flow of suspensions of charged colloids with a\nmesoscopic method that allows to model generic experimental conditions. We show\nthat for highly charged colloids their electrophoretic mobility increases\nsignificantly and displays a mobility maximum on increasing the colloidal\ncharge for all salt concentrations. The electrophoretic mobility of highly\ncharged colloids is also enhanced significantly when ion advection is dominant,\nleading to a strong heterogeneity in the local electrophoretic response\nespecially at low salt concentration, when ion diffuse layers overlap."
    },
    {
        "anchor": "Relative entropy of freely cooling granular gases. A molecular dynamics\n  study: Whereas the original Boltzmann's $H$-theorem applies to elastic collisions,\nits rigorous generalization to the inelastic case is still lacking.\nNonetheless, it has been conjectured in the literature that the relative\nentropy of the velocity distribution function with respect to the homogeneous\ncooling state (HCS) represents an adequate nonequilibrium entropy-like\nfunctional for an isolated freely cooling granular gas. In this work, we\npresent molecular dynamics results reinforcing this conjecture and rejecting\nthe choice of the Maxwellian over the HCS as a reference distribution. These\nresults are qualitatively predicted by a simplified theoretical toy model.\nAdditionally, a Maxwell-demon-like velocity-inversion simulation experiment\nhighlights the microscopic irreversibility of the granular gas dynamics,\nmonitored by the relative entropy, where a short ``anti-kinetic'' transient\nregime appears for nearly elastic collisions only.",
        "positive": "Lateral Separation of Macromolecules and Polyelectrolytes in\n  Microlithographic Arrays: A new approach to separation of a variety of microscopic and mesoscopic\nobjects in dilute solution is presented. The approach takes advantage of unique\nproperties of a specially designed separation device (sieve), which can be\nreadily built using already developed microlithographic techniques. Due to the\nbroken reflection symmetry in its design, the direction of motion of an object\nin the sieve varies as a function of its self-diffusion constant, causing\nseparation transverse to its direction of motion. This gives the device some\nsignificant and unique advantages over existing fractionation methods based on\ncentrifugation and electrophoresis."
    },
    {
        "anchor": "A geometrical description of charge distribution on the disordered\n  conductor surfaces: This paper considers the distribution of charge over the surface of a\nconductor, and specifically the old rule-of-thumb that charge accumulates near\nsharp points and more generally in regions of high curvature. The discussion is\nalmost entirely qualitative. Various conductors with different geometric shapes\nhave been considered and the charge density on their points has been compared.\nOur discussion shows that the statement \"surface charge density is higher at\npoints with greater curvature\" does not seem to be true and at least it can be\nmodified. We have avoided unnecessary relationships as much as possible and\ntried to follow the discussion qualitatively.",
        "positive": "Rheological consequences of wet and dry friction in a dumbbell model\n  with hydrodynamic interactions and internal viscosity: The effect of fluctuating internal viscosity and hydrodynamic interactions on\na range of rheological properties of dilute polymer solutions is examined using\na finitely extensible dumbbell model for a polymer. Brownian dynamics\nsimulations are used to compute both transient and steady state viscometric\nfunctions in shear flow. The results enable a careful differentiation of the\ninfluence, on rheological properties, of solvent-mediated friction from that of\na dissipative mechanism that is independent of solvent viscosity. In\nparticular, hydrodynamic interactions have a significant influence on the\nmagnitude of the stress jump at the inception of shear flow, and on the\ntransient viscometric functions, but a negligible effect on the steady state\nviscometric functions at high shear rates. Zero-shear rate viscometric\nfunctions of free-draining dumbbells remain essentially independent of the\ninternal viscosity parameter, as predicted by the Gaussian approximation, but\nthe inclusion of hydrodynamic interactions induces a dependence on both the\nhydrodynamic interaction and the internal viscosity parameter. Large values of\nthe internal viscosity parameter lead to linear viscoelastic predictions that\nmimic the behavior of rigid dumbbell solutions. On the other hand, steady-shear\nviscometric functions at high shear rates differ in general from those for\nrigid dumbbells, depending crucially on the finite extensibility of the\ndumbbell spring."
    },
    {
        "anchor": "Cell dynamics simulation of droplet and bridge formation within striped\n  nano-capillaries: The kinetics of droplet and bridge formation within striped nano-capillaries\nis studied when the wetting film grows via interface-limited growth. The\nphenomenological time-dependent Ginzburg-Landau (TDGL)-type model with thermal\nnoise is used and numerically solved using the cell dynamics method. The model\nis two-dimensional and consists of undersaturated vapor confined within a\nnano-capillary made of two infinitely wide flat substrates. The surface of the\nsubstrate is chemically heterogeneous with a single stripe of lyophilic domain\nthat exerts long-range attractive potential to the vapor molecule. The dynamics\nof nucleation and subsequent growth of droplet and bridge can be simulated and\nvisualized. In particular, the evolution of the morphology from droplet or bump\nto bridge is clearly identified. Crucial role played by the substrate potential\non the morphology of bridge of nanoscopic size is clarified. Nearly\ntemperature-independent evolution of capillary condensation is predicted when\nthe interface-limited growth dominates. In addition, it is shown that the\ndynamics of capillary condensation follows the scenario of capillary\ncondensation proposed by Everett and Haynes three decades ago.",
        "positive": "Noether-Constrained Correlations in Equilibrium Liquids: Liquid structure carries deep imprints of an inherent thermal invariance\nagainst a spatial transformation of the underlying classical many-body\nHamiltonian. At first order in the transformation field the Noether theorem\nyields the local force balance. Three distinct two-body correlation functions\nemerge at second order, namely the standard two-body density, the localized\nforce-force correlation function, and the localized force gradient. An exact\nNoether sum rule interrelates these correlators. Simulations of Lennard-Jones,\nYukawa, soft-sphere dipolar, Stockmayer, Gay-Berne and Weeks-Chandler-Andersen\nliquids, of monatomic water and of a colloidal gel former demonstrate their\nfundamental role in the characterization of spatial structure."
    },
    {
        "anchor": "Observation of ultra-slow shock waves in a tunable magnetic lattice: The combination of fast propagation speeds and highly localized nature has\nhindered the direct observation of the evolution of shock waves at the\nmolecular scale. To address this limitation, an experimental system is designed\nby tuning a one-dimensional magnetic lattice to evolve benign wave forms into\nshock waves at observable spatial and temporal scales, thus serving as a\n'magnifying glass' to illuminate shock processes. An accompanying analysis\nconfirms that the formation of strong shocks is fully captured. The exhibited\nlack of a steady state induced by indefinite expansion of a disordered\ntransition zone points to the absence of local thermodynamic equilibrium, and\nresurfaces lingering questions on the validity of continuum assumptions in\npresence of strong shocks.",
        "positive": "On the Adsorption of Two-State Polymers: Monte Carlo(MC) simulations produce evidence that annealed copolymers\nincorporating two interconverting monomers, P and H, adsorb as homopolymers\nwith an effective adsorption energy per monomer, $\\epsilon_{eff}$, that depends\non the PH equilibrium constants in the bulk and at the surface. The cross-over\nexponent, $\\Phi,$ is unmodified. The MC results on the overall PH ratio, the PH\nratio at the surface and in the bulk as well as the number of adsorbed monomers\nare in quantitative agreement with this hypothesis and the theoretically\nderived $\\epsilon_{eff}$. The evidence suggests that the form of surface\npotential does not affect $\\Phi$ but does influence the PH equilibrium."
    },
    {
        "anchor": "Modelling segregation of flowing bidisperse granular mixtures varying\n  simultaneously in size and density: Flowing granular materials segregate due to differences in particle size\n(driven by percolation) and density (driven by buoyancy). Modelling the\nsegregation of mixtures of large/heavy particles and small/light particles is\nchallenging due to the opposing effects of the two segregation mechanisms.\nUsing discrete element method (DEM) simulations of combined size and density\nsegregation we show that the segregation velocity is well described by a model\nthat depends linearly on the local shear rate and quadratically on the species\nconcentration. Concentration profiles predicted by incorporating this\nsegregation velocity model into a continuum advection-diffusion-segregation\ntransport model match DEM simulation results well for a wide range of particle\nsize and density ratios. Most surprisingly, the DEM simulations and the\nsegregation velocity model both show that the segregation direction for a range\nof size and density ratios depends on the local species concentration. This\nleads to a methodology to determine the combination of particle size ratio,\ndensity ratio, and particle concentration for which a bidisperse mixture will\nnot segregate.",
        "positive": "Computational design of armored nanodroplets as nanocarriers for\n  encapsulation and release under flow conditions: Nanocarriers are nanosized materials commonly used for targeted-oriented\ndelivery of active compounds, including antimicrobials and small-molecular\ndrugs. They equally represent fundamental and engineering challenges since\nsophisticated nanocarriers must show adequate structure, stability, and\nfunction in complex ambients. Here, we report on the computational design of a\ndistinctive class of nanocarriers, built from buckled armored nanodroplets,\nable to selectively encapsulate or release a probe load under specific flow\nconditions. Mesoscopic simulations offer detailed insight into the interplay\nbetween the characteristics of laden surface coverage and evolution of the\ndroplet morphology. First, we describe in detail the formation of\n\\textit{pocket-like} structures in Pickering emulsion nanodroplets and their\nstability under external flow. Then we use that knowledge to test the capacity\nof these emulsion-based pockets to yield flow-assisted encapsulation or\nexpulsion of a probe load. Finally, the rheological properties of our model\ncarrier are put into perspective with those of delivery systems employed in\npharmaceutical and cosmetic technology."
    },
    {
        "anchor": "Loose packings of frictional spheres: We have produced loose packings of cohesionless, frictional spheres by\nsequential deposition of highly-spherical, monodisperse particles through a\nfluid. By varying the properties of the fluid and the particles, we have\nidentified the Stokes number (St) - rather than the buoyancy of the particles\nin the fluid - as the parameter controlling the approach to the loose packing\nlimit. The loose packing limit is attained at a threshold value of St at which\nthe kinetic energy of a particle impinging on the packing is fully dissipated\nby the fluid. Thus, for cohesionless particles, the dynamics of the deposition\nprocess, rather than the stability of the static packing, defines the random\nloose packing limit. We have made direct measurements of the interparticle\nfriction in the fluid, and present an experimental measurement of the loose\npacking volume fraction, \\phi_{RLP}, as a function of the friction coefficient\n\\mu_s.",
        "positive": "Patterning droplets with durotaxis: Numerous cell-types have shown a remarkable ability to detect and move along\ngradients in stiffness of an underlying substrate -- a process known as\ndurotaxis. The mechanisms underlying durotaxis are still unresolved, but\ngenerally believed to involve active sensing and locomotion. Here, we show that\nsimple liquid droplets also undergo durotaxis. By modulating substrate\nstiffness, we obtain fine control of droplet position on soft, flat substrates.\nUnlike other control mechanisms, droplet durotaxis works without imposing\nchemical, thermal, electrical or topographical gradients. This enables a new\napproach to large-scale droplet patterning and is potentially useful for many\napplications, such as microfluidics, thermal control and microfabrication."
    },
    {
        "anchor": "A hackable, multi-functional, and modular extrusion 3D printer for soft\n  materials: Three-dimensional (3D) printing has emerged as a powerful tool for material,\nfood, and life science research and development, where the technology\ndemocratization necessitates the advancement of open-source platforms. Herein,\nwe developed a hackable, multi-functional, and modular extrusion 3D printer for\nsoft materials, nicknamed Printer.HM. Multi-printhead modules are established\nbased on a robotic arm for heterogeneous construct creation, where ink\nprintability can be tuned by accessories such as heating and UV modules.\nSoftware associated with Printer.HM were designed to accept geometry inputs\nincluding computer-aided design models, coordinates, equations, and pictures,\nto create prints of distinct characteristics. Printer.HM could further perform\nversatile operations, such as liquid dispensing, non-planar printing, and\npick-and-place of meso-objects. By mix-and-match software and hardware\nsettings, Printer.HM demonstrated printing of pH-responsive soft actuators,\nplant-based functional hydrogels, and organ macro-anatomical models.\nIntegrating affordability and open design, we envisage the Printer.HM concept\nto widen open innovations for soft, biological, and sustainable material\narchitectures.",
        "positive": "Balance of enthalpy and entropy in depletion forces: Solutes added to solutions often dramatically impact molecular processes\nranging from the suspension or precipitation of colloids to biomolecular\nassociations and protein folding. Here we revisit the origins of the effective\nattractive interactions that emerge between and within macromolecules immersed\nin solutions containing cosolutes that are preferentially excluded from the\nmacromolecular interfaces. Until recently, these depletion forces were\nconsidered to be entropic in nature, resulting primarily from the tendency to\nincrease the space available to the cosolute. However, recent experimental\nevidence indicates the existence of additional, energetically-dominated\nmechanisms. In this review we follow the emerging characteristics of these\ndifferent mechanisms. By compiling a set of available thermodynamic data for\nprocesses ranging from protein folding to protein-protein interactions, we show\nthat excluded cosolutes can act through two distinct mechanisms that correlate\nto a large extent with their molecular properties. For many polymers at low to\nmoderate concentrations the steric interactions and molecular crowding effects\ndominate, and the mechanism is entropic. To contrast, for many small excluded\nsolutes, such as naturally occurring osmolytes, the mechanism is dominated by\nfavorable enthalpy, whereas the entropic contribution is typically unfavorable.\nWe review the available models for these thermodynamic mechanisms, and comment\non the need for new models that would be able to explain the full range of\nobserved depletion forces."
    },
    {
        "anchor": "Minimal Model for Hydrodynamic Synchronization: Motivated by the observed coordination of nearby beating cilia, we use a\nscale model experiment to show that hydrodynamic interactions can cause\nsynchronization between rotating paddles driven at constant torque in a very\nviscous fluid. Synchronization is only observed when the shafts supporting the\npaddles have some flexibility. The phase difference in the synchronized state\ndepends on the symmetry of the paddles. We use the method of regularized\nstokeslets to model the paddles and find excellent agreement with the\nexperimental observations. We also use a simple analytic theory based on\nfar-field approximations to derive scaling laws for the synchronization time as\na function of paddle separation.",
        "positive": "Limits of the equivalence of time and ensemble averages in shear flows: In equilibrium systems, time and ensemble averages of physical quantities are\nequivalent due to ergodic exploration of phase space. In driven systems, it is\nunknown if a similar equivalence of time and ensemble averages exists. We\nexplore effective limits of such convergence in a sheared bubble raft using\naverages of the bubble velocities. In independent experiments, averaging over\ntime leads to well converged velocity profiles. However, the time-averages from\nindependent experiments result in distinct velocity averages. Ensemble averages\nare approximated by randomly selecting bubble velocities from independent\nexperiments. Increasingly better approximations of ensemble averages converge\ntoward a unique velocity profile. Therefore, the experiments establish that in\npractical realizations of non-equilibrium systems, temporal averaging and\nensemble averaging can yield convergent (stationary) but distinct\ndistributions."
    },
    {
        "anchor": "Evolution of instabilities in filament buckling processes: In this work we study the dynamical buckling process of a thin filament\nimmersed in a high viscous medium. We perform an experimental study to track\nthe shape evolution of the filament during a constant velocity compression.\nNumerical simulations reproduce the dynamical features observed for the\nexperimental data and allow quantifying the filament's load.\n  We observe that both the filament's load and the wavenumber evolve in a\nstep-wise manner. To achieve a physical insight of the process we apply a\ntheoretical model to describe the buckling of a filament in a viscous medium.\nWe solve a hydrodynamic equation in terms of normal modes for clamped-clamped\nboundary conditions and applied constant load. We find a good agreement with\nexperimental data and simulations, suggesting that the proposed mechanistic\nmodel captures the essential features underlying the dynamical buckling\nprocess.",
        "positive": "Mixtures of self-propelled particles interacting with asymmetric\n  obstacles: In the presence of an obstacle, active particles condensate into a surface\n\"wetting\" layer due to persistent motion. If the obstacle is asymmetric, a\nrectification current arises in addition to wetting. Asymmetric geometries are\ntherefore commonly used to concentrate microorganisms like bacteria and sperms.\nHowever, most studies neglect the fact that biological active matter is\ndiverse, composed of individuals with distinct self-propulsions. Using\nsimulations, we study a mixture of \"fast\" and \"slow\" active Brownian disks in\ntwo dimensions interacting with large half-disk obstacles. With this\nprototypical obstacle geometry, we analyze how the stationary collective\nbehavior depends on the degree of self-propulsion \"diversity\", defined as\nproportional to the difference between the self-propulsion speeds, while\nkeeping the average self-propulsion speed fixed. A wetting layer rich in fast\nparticles arises. The rectification current is amplified by speed diversity due\nto a superlinear dependence of rectification on self-propulsion speed, which\narises from cooperative effects. Thus, the total rectification current cannot\nbe obtained from an effective one-component active fluid with the same average\nself-propulsion speed, highlighting the importance of considering diversity in\nactive matter. Finally, rectification alters particle evaporation and\nabsorption by the layer, making the density of the dilute phase increase with\nthe global density. Therefore, the steady state violates the lever rule, a\nresult which is valid even for systems of identical particles."
    },
    {
        "anchor": "Migration and separation of polymers in non-uniform active baths: Polymer-like structures are ubiquitous in nature and synthetic materials.\nTheir configurational and migration properties are often affected by crowded\nenvironments leading to non-thermal fluctuations. Here, we study an ideal Rouse\nchain in contact with a non-homogeneous active bath, characterized by the\npresence of active self-propelled agents which exert time-correlated forces on\nthe chain. By means of a coarse-graining procedure, we derive an effective\nevolution for the center of mass of the chain and show its tendency to migrate\ntowards and preferentially localize in regions of high/low bath activity\ndepending on the model parameters. In particular, we demonstrate that an active\nbath with non-uniform activity can be used to separate efficiently polymeric\nspecies with different lengths and/or connectivity.",
        "positive": "Frictional Active Brownian Particles: Frictional forces affect the rheology of hard-sphere colloids, at high shear\nrate. Here we demonstrate, via numerical simulations, that they also affect the\ndynamics of active Brownian particles, and their motility induced phase\nseparation. Frictional forces increase the angular diffusivity of the\nparticles, in the dilute phase, and prevent colliding particles from resolving\ntheir collision by sliding one past to the other. This leads to qualitatively\nchanges of motility-induced phase diagram in the volume-fraction motility\nplane. While frictionless systems become unstable towards phase separation as\nthe motility increases only if their volume fraction overcomes a threshold,\nfrictional system become unstable regardless of their volume fraction. These\nresults suggest the possibility of controlling the motility induced phase\ndiagram by tuning the roughness of the particles."
    },
    {
        "anchor": "Fluid transport at low Reynolds number with magnetically actuated\n  artificial cilia: By numerical modeling we investigate fluid transport in low-Reynolds-number\nflow achieved with a special elastic filament or artifical cilium attached to a\nplanar surface. The filament is made of superparamagnetic particles linked\ntogether by DNA double strands. An external magnetic field induces dipolar\ninteractions between the beads of the filament which provides a convenient way\nof actuating the cilium in a well-controlled manner. The filament has recently\nbeen used to successfully construct the first artificial micro-swimmer [R.\nDreyfus at al., Nature 437, 862 (2005)]. In our numerical study we introduce a\nmeasure, which we call pumping performance, to quantify the fluid transport\ninduced by the magnetically actuated cilium and identify an optimum stroke\npattern of the filament. It consists of a slow transport stroke and a fast\nrecovery stroke. Our detailed parameter study also reveals that for\nsufficiently large magnetic fields the artificial cilium is mainly governed by\nthe Mason number that compares frictional to magnetic forces. Initial studies\non multi-cilia systems show that the pumping performance is very sensitive to\nthe imposed phase lag between neighboring cilia, i.e., to the details of the\ninitiated metachronal wave.",
        "positive": "Colloidal Directional Structures at a Nematic Liquid Crystal-Air\n  Interface: We present a variety of structures formed by colloidal droplets at a nematic\nliquid crystal-air interface, where the elastic dipole-dipole,\nquadrupole-quadrupole, and dipole-quadrupole interactions are all essentially\ninvolved. The colloidal structures observed not only include chains with kinks\nor clusters, but also comprise directional structures, such as directional\nchains and branches, whose direction is associated with the tilting director in\nthe liquid crystal layer. The dipole-quadrupole interaction, originating from\nthe polydispersity of the droplets, plays a central role for the formation of\nthese directional structures. Clusters consisting of directional branches and\nchains are also observed and found to be fractal statistically."
    },
    {
        "anchor": "Active crystals on a sphere: Two-dimensional crystals on curved manifolds exhibit nontrivial defect\nstructures. Here, we consider \"active crystals\" on a sphere, which are composed\nof self-propelled colloidal particles. Our work is based on a new\nphase-field-crystal-type model that involves a density and a polarization field\non the sphere. Depending on the strength of the self-propulsion, three\ndifferent types of crystals are found: a static crystal, a self-spinning\n\"vortex-vortex\" crystal containing two vortical poles of the local velocity,\nand a self-translating \"source-sink\" crystal with a source pole where\ncrystallization occurs and a sink pole where the active crystal melts. These\ndifferent crystalline states as well as their defects are studied theoretically\nhere and can in principle be confirmed in experiments.",
        "positive": "Ultrasoft classical systems at zero temperature: At low temperatures ultrasoft particle systems develop interesting phases via\nthe self-assembly of particle clusters. In this study we develop a general\nzero-temperature analysis fully characterizing the ground state of such models\nin two and three dimensions, considering the classical system with the\nrestriction of a constant integer number of particles per cluster. We show that\nthis methodology allows for an exact prediction of the actual density values at\nwhich the different phases emerge, including the zones of uneven cluster\noccupation, which are studied as coexistence regions of two pure phases. Beyond\nthe method itself, designed to produce exact phase diagrams from general\nultrasoft potentials, we reach analytical expressions for the energy and\nlocation of the different phases in the large occupancy limit."
    },
    {
        "anchor": "Motility of Colonial Choanoflagellates and the Statistics of Aggregate\n  Random Walkers: We illuminate the nature of the three-dimensional random walks of\nmicroorganisms composed of individual organisms adhered together. Such\n$aggregate~random~walkers$ are typified by choanoflagellates, eukaryotes that\nare the closest living relatives of animals. In the colony-forming species\n$Salpingoeca~rosetta$ we show that the beating of each flagellum is stochastic\nand uncorrelated with others, and the vectorial sum of the flagellar propulsion\nmanifests as stochastic helical swimming. A quantitative theory for these\nresults is presented and species variability discussed.",
        "positive": "Analysis of a growing dynamic length scale in a glass-forming binary\n  hard-sphere mixture: We examine a length scale that characterizes the spatial extent of\nheterogeneous dynamics in a glass-forming binary hard-sphere mixture up to the\nmode-coupling volume fraction phi_c. First, we characterize the system's\ndynamics. Then, we utilize a new method [Phys. Rev. Lett. 105, 217801 (2010)]\nto extract and analyze the ensemble independent dynamic susceptibility chi_4(t)\nand the dynamic correlation length xi(t) for a range of times between the beta\nand alpha relaxation times. We find that in this time range the dynamic\ncorrelation length follows a volume fraction independent curve xi(t) ~ ln(t).\nFor longer times, xi(t) departs from this curve and remains constant up to the\nlargest time at which we can determine the length accurately. In addition to\nthe previously established correlation tau_alpha ~ exp[xi(tau_alpha)] between\nthe alpha relaxation time, tau_alpha, and the dynamic correlation length at\nthis time, xi(tau_alpha), we also find a similar correlation for the diffusion\ncoefficient D ~ exp[xi(tau_alpha)^theta] with theta approximately 0.6. We\ndiscuss the relevance of these findings for different theories of the glass\ntransition."
    },
    {
        "anchor": "Nonlinear analysis of the fluid-solid transition in a model for ordered\n  biological tissues: The rheology of biological tissues is important for their function, and we\nwould like to better understand how single cells control global tissue\nproperties such as tissue fluidity. A confluent tissue can fluidize when cells\ndiffuse by executing a series of cell rearrangements, or T1 transitions. In a\ndisordered 2D vertex model, the tissue fluidizes when the T1 energy barriers\ndisappear as the target shape index approaches a critical value ($s^*_{0} \\sim\n3.81$), and the shear modulus describing the linear response also vanishes at\nthis same critical point. However, the ordered ground states of 2D vertex\nmodels become linearly unstable at a lower value of the target shape index\n(3.72) [1,2]. We investigate whether the ground states of the 2D vertex model\nare fluid-like or solid-like between 3.72 and 3.81 $-$ does the \"equation of\nstate\" for these systems have two branches, like glassy particulate matter, or\nonly one? Using four-cell and many-cell numerical simulations, we demonstrate\nthat for a hexagonal ground state, T1 energy barriers only vanish at $\\sim\n3.81$, indicating that ordered systems have the same critical point as\ndisordered systems. We also develop a simple geometric argument that correctly\npredicts how non-linear stabilization disappears at $s^*_{0}$ in ordered\nsystems.",
        "positive": "Viscosity and Diffusion: Crowding and Salt Effects in Protein Solutions: We report on a joint experimental-theoretical study of collective diffusion\nin, and static shear viscosity of solutions of bovine serum albumin (BSA)\nproteins, focusing on the dependence on protein and salt concentration. Data\nobtained from dynamic light scattering and rheometric measurements are compared\nto theoretical calculations based on an analytically treatable spheroid model\nof BSA with isotropic screened Coulomb plus hard-sphere interactions. The only\ninput to the dynamics calculations is the static structure factor obtained from\na consistent theoretical fit to a concentration series of small-angle X-ray\nscattering (SAXS) data. This fit is based on an integral equation scheme that\ncombines high accuracy with low computational cost. All experimentally probed\ndynamic and static properties are reproduced theoretically with an at least\nsemi-quantitative accuracy. For lower protein concentration and low salinity,\nboth theory and experiment show a maximum in the reduced viscosity, caused by\nthe electrostatic repulsion of proteins. The validity range of a generalized\nStokes-Einstein (GSE) relation connecting viscosity, collective diffusion\ncoefficient, and osmotic compressibility, proposed by Kholodenko and Douglas\n[PRE 51, 1081 (1995)] is examined. Significant violation of the GSE relation is\nfound, both in experimental data and in theoretical models, in semi-dilute\nsystems at physiological salinity, and under low-salt conditions for arbitrary\nprotein concentrations."
    },
    {
        "anchor": "The electrical double layer for a fully asymmetric electrolyte around a\n  spherical colloid: an integral equation study: The hypernetted chain/mean spherical approximation (HNC/MSA) integral\nequation is obtained and solved numerically for a totally asymmetric primitive\nmodel electrolyte around a spherical macroparticle. The ensuing radial\ndistribution functions show a very good agreement when compared to our Monte\nCarlo and molecular dynamics simulations for spherical geometry and with\nrespect to previous anisotropic reference HNC calculations in the planar limit.\nWe report an analysis of the potential vs charge relationship, radial\ndistribution functions, mean electrostatic potential and cumulative reduced\ncharge for representative cases of 1:1 and 2:2 salts with a size asymmetry\nratio of 2. Our results are collated with those of the Modified Gouy-Chapman\n(MGC) and unequal radius Modified Gouy-Chapman (URMGC) theories and with those\nof HNC/MSA in the restricted primitive model (RPM) to assess the importance of\nsize asymmetry effects. One of the most striking characteristics found is\nthat,\\textit{contrary to the general belief}, away from the point of zero\ncharge the properties of an asymmetric electrical double layer (EDL) are not\nthose corresponding to a symmetric electrolyte with the size and charge of the\ncounterion, i.e. \\textit{counterions do not always dominate}. This behavior\nsuggests the existence of a new phenomenology in the EDL that genuinely belongs\nto a more realistic size-asymmetric model where steric correlations are taken\ninto account consistently. Such novel features can not be described by\ntraditional mean field theories like MGC, URMGC or even by enhanced formalisms,\nlike HNC/MSA, if they are based on the RPM.",
        "positive": "X-Ray Study of Thermotropic Mesophases of an n-Triacontanol Adsorption\n  Film at the n-Hexadecane - Water Interface: Using synchrotron radiation with a photon energy of 15 keV, the molecular\nstructure of an adsorbed n-triacontanol layer at the n-hexadecane - water\ninterface in different its phase states has been studied by the method of\ndiffuse X-ray scattering. The analysis of the experimental data shows that a\ntransition to the multilayer adsorption occurs at a temperature below the\ntwo-dimensional vapor - liquid transition at the interface. This transition has\nbeen attributed to a feature in the temperature dependence of the concentration\nof micelles in a surface layer 100 - 200 {\\AA} thick."
    },
    {
        "anchor": "Criticality in an imidazolium ionic liquid fully wetting a sapphire\n  support: Hypothesis: Ionic liquids have various applications in catalytic reaction\nenvironments. In those systems, their interaction with interfaces is key to\ntheir performance as a liquid phase. We hypothesize that the way a monolayer\nionic liquid phase interacts with interfaces like a sapphire substrate is\nsignificantly dependent on temperature and that critical behavior can be\nobserved in the structural properties of the liquid film.\n  Methods and simulations: We perform molecular dynamics simulations of\nimidazolium-based ionic liquid monolayers deposited on a sapphire substrate at\ntemperatures from 200K to 400K. We develop computational tools to analyze\nstructural properties of molecular arrangement in the monolayer, the structure\nof the film and the defects spontaneously forming and healing.\n  Findings: We observe a clear structural phase transition at around 300K from\na solid-like to a liquid-like behavior of a film. Below the critical point an\nalternating crystalline structure of cations and anions with alignment of\nperiodic vectors with the underlying substrate grid is observed, with frozen\ndefects. Above the critical temperature, the pattern becomes isotropic within\nthe contact layer that displays dynamic defects of a characteristic size. Our\nresults highlight the importance of confinement to the phase behavior of the\nsystem.",
        "positive": "Challenges in theoretical investigations on configurations of lipid\n  membranes: This review reports some key results in theoretical investigations on\nconfigurations of lipid membranes and presents several challenges in this field\nwhich involve (i) exact solutions to the shape equation of lipid vesicles; (ii)\nexact solutions to the governing equations of open lipid membranes; (iii) neck\ncondition of two-phase vesicles in the budding state; (iv) nonlocal theory of\nmembrane elasticity; (v) relationship between symmetry and the magnitude of\nfree energy."
    },
    {
        "anchor": "Superfluid vs Ferromagnetic Behaviour in a Bose Gas of Spin-1/2 Atoms: We study the thermodynamic phases of a gas of spin-1/2 atoms in the\nHartree-Fock approximation. Our main result is that, for repulsive or\nweakly-attractive inter-component interaction strength, the superfluid and\nferromagnetic phase transitions occur at the same temperature. For\nstrongly-attractive inter-component interaction strength, however, the\nferromagnetic phase transition occurs at a higher temperature than the\nsuperfluid phase transition. We also find that the presence of a condensate\nacts as an effective magnetic field that polarizes the normal cloud. We finally\ncomment on the validity of the Hartree-Fock approximation in describing\ndifferent phenomena in this system.",
        "positive": "Breakdown of Stokes-Einstein relation in supercooled water: Water displays breakdown of the Stokes-Einstein relation at low temperatures.\nWe hypothesize that the breakdown is a result of the structural changes and a\nsharp rise in dynamic heterogeneities that occurs low T upon crossing the Widom\nline."
    },
    {
        "anchor": "Hydrodynamics of an inelastic gas with implications for sonochemistry: The hydrodynamics for a gas of hard-spheres which sometimes experience\ninelastic collisions resulting in the loss of a fixed, velocity-independent,\namount of energy $\\Delta $ is investigated with the goal of understanding the\ncoupling between hydrodynamics and endothermic chemistry. The homogeneous\ncooling state of a uniform system and the modified Navier-Stokes equations are\ndiscussed and explicit expressions given for the pressure, cooling rates and\nall transport coefficients for D-dimensions. The Navier-Stokes equations are\nsolved numerically for the case of a two-dimensional gas subject to a circular\npiston so as to illustrate the effects of the enegy loss on the structure of\nshocks found in cavitating bubbles. It is found that the maximal temperature\nachieved is a sensitive function of $\\Delta $ with a minimum occuring near the\nphysically important value of $\\Delta \\sim 12,000K \\sim 1eV$",
        "positive": "Hard convex lens-shaped particles: Characterization of dense disordered\n  packings: Among the family of hard convex lens-shaped particles (lenses), the one with\naspect ratio equal to 2/3 is `optimal' in the sense that the maximally random\njammed (MRJ) packings of such lenses achieve the highest packing fraction\n$\\phi_{\\rm MRJ} \\simeq 0.73$. This value is only a few percent lower than\n$\\phi_{\\rm DKP} = 0.76210\\dots$, the packing fraction of the corresponding\ndensest-known crystalline (degenerate) packings. By exploiting the appreciably\nreduced propensity that a system of such optimal lenses has to positionally and\norientationally order, disordered packings of them are progressively generated\nby a Monte Carlo method-based procedure from the dilute equilibrium isotropic\nfluid phase to the dense nonequilibrium MRJ state. This allows one to closely\nmonitor how the (micro)structure of these packings changes in the process of\nformation of the MRJ state. The gradual changes undergone by the many\nstructural descriptors calculated can coherently and consistently be traced\nback to the gradual increase in contacts between the hard particles until the\nisostatic mean value of 10 contact neighbors per lens is reached at the\neffectively hyperuniform MRJ state. Compared to the MRJ state of hard spheres,\nthe MRJ state of such optimal lenses is denser (less porous), more disordered,\nand rattler-free. This set of characteristics makes them good glass formers. It\nis possible that this conclusion may also hold for other hard convex uniaxial\nparticles with a correspondingly similar aspect ratio, be they oblate or\nprolate, and that, by using suitable biaxial variants of them, that set of\ncharacteristics might further improve."
    },
    {
        "anchor": "Rapid Stabilization of Droplets by Particles in Microfluidics: Role of\n  Droplet Formation: Droplet-based microfluidics has emerged as a powerful technology for the\nminiaturization and automation of biochemical assays. The replacement of\nsurfactants by nanoparticles as interfacial stabilizers has gained increasing\ninterest. However, the stabilization mechanism of droplets by nanoparticles in\nmicrochannels is poorly understood, drastically hindering the development of\npractical applications. Current methods for droplet stabilization involve a\ntrade-off between low droplet production throughput and waste of large number\nof nanoparticles. Here, we introduce a modification to the droplet production\njunction that reduces the droplet stabilization time by an order of magnitude,\nand at the same time significantly reduces the particle waste. Our results show\nthat the limiting step in the kinetics of stabilization is the initial time\nwhere both phases come into contact and offer a guideline for the design of\nparticle-stabilized droplet production devices.",
        "positive": "Fickian yet non-Gaussian behaviour: A dominant role of the intermittent\n  dynamics: We present a study of the dynamics of small solute particles in a solvent\nmedium where the solute is much smaller in size, mimicking the diffusion of\nsmall particles in crowded environment. The solute exhibits Fickian diffusion\narising from non-Gaussian Van Hove correlation function. Our study shows that\nthere are at least two possible origins of this non-Gaussian behaviour: the\ndecoupling of the solute-solvent dynamics and the intermittency in the solute\nmotion, the latter playing a dominant role. In the former scenario when\naveraged over time long enough to explore different solvent environments, the\ndynamics recovers the Gaussian nature. In the case of intermittent dynamics the\nnon-Gaussianity remains even after long averaging and the Gaussian behaviour is\nobtained at a much longer time. Our study further shows that only for an\nintermediate attractive solute-solvent interaction the dynamics of the solute\nis intermittent. The intermittency disappears for weaker or stronger\nattractions."
    },
    {
        "anchor": "Relative Evaporation Probabilities of 3He and 4He from the Surface of\n  Superfluid 4He: We report a preliminary experiment which demonstrates that 3He atoms in\nAndreev states are evaporated by high-energy (E/k_B ~ 10.2 K) phonons in a\nquantum evaporation process similar to that which occurs in pure 4He. Under\nconditions of low 3He coverage, high-energy phonons appear to evaporate 3He and\n4He atoms with equal probability. However, we have not managed to detect any\n3He atoms that have been evaporated by rotons, and conclude that the\nprobability of a roton evaporating a 3He atom is less than 2% of the\nprobability that it evaporates a 4He atom.",
        "positive": "Cascade or not cascade? Energy transfer and elastic effects in active\n  nematics: We numerically study the multi-scale properties of a 2d active gel to address\nthe energy transfer mechanism. We find that activity is able to excite\nlong-ranged distortions of the nematic pattern giving rise to spontaneous\nlaminar flows and to a chaotic regime by further increasing the rate of active\nenergy injection. By means of a scale-to-scale spectral analysis we find that\nthe gel is basically driven by the local balancing between active injection and\nviscous dissipation, without any signal of non-linear hydrodynamical transfer\nand turbulent cascades. Furthermore, elasticity may qualitatively play an\nimportant role by transferring energy from small to larger scales through\nnemato-hydrodynamic interactions."
    },
    {
        "anchor": "Profiles of electrostatic potential across the water-vapor, ice-vapor\n  and ice-water interfaces: Ice-water, water-vapor interfaces and ice surface are studied by molecular\ndynamics simulations with the SPC/E model of water molecules having the purpose\nto estimate the profiles of electrostatic potential across the interfaces. We\nhave proposed a methodology for calculating the profiles of electrostatic\npotential based on a trial particle, which showed good agreement for the case\nof electrostatic potential profile of the water-vapor interface of TIP4P model\ncalculated in another way. The measured profile of electrostatic potential for\nthe pure ice-water interface decreases towards the liquid bulk region, which is\nin agreement with simulations of preferential direction of motion of Li$^{+}$\nand F$^{-}$ solute ions at the liquid side of the ice-water interface. These\nresults are discussed in connection with the Workman-Reynolds effect.",
        "positive": "Tuning the permeability of dense membranes by shaping nanoscale\n  potentials: The permeability is one of the most fundamental transport properties in soft\nmatter physics, material engineering, and nanofluidics. Here we report by means\nof Langevin simulations of ideal penetrants in a nanoscale membrane made of a\nfixed lattice of attractive interaction sites, how the permeability can be\nmassively tuned, even minimized or maximized, by tailoring the potential energy\nlandscape for the diffusing penetrants, depending on the membrane attraction,\ntopology, and density. Supported by limiting scaling theories we demonstrate\nthat the observed non-monotonic behavior and the occurrence of extreme values\nof the permeability is far from trivial and triggered by a strong\nanti-correlation and substantial (orders of magnitude) cancellation between\npenetrant partitioning and diffusivity, especially within dense and highly\nattractive membranes."
    },
    {
        "anchor": "Molecular layers in thin supported films exhibit the same scaling as the\n  bulk between slow relaxation and vibrational dynamics: We perform molecular dynamics simulations of a supported molecular thin film.\nBy varying thickness and temperature, we observe anisotropic mobility as well\nas strong gradients of both the vibrational motion and the structural\nrelaxation through film layers with monomer size thickness. We show that the\ngradients of the fast and the slow dynamics across the layers (except the\nadherent layer to the substrate) comply, without any adjustment, with the same\nscaling between the structural relaxation time and the Debye Waller factor\noriginally observed in the bulk [Larini et al., Nat. Phys., 2008, 4, 42]. The\nscaling is not observed if the average dynamics of the film is inspected. Our\nresults suggest that the solidification process of each layer may be tracked by\nknowing solely the vibrational properties of the layer and the bulk.",
        "positive": "Shear profile in a dense packing of large grains: We investigate the shear of a dense bed of refracting supermillimetric grains\nconfined within a transparent horizontal annular cell with a rotating top. The\nlocal time correlation functions of interferometric images allow to\ncharacterize the shear profile close to the wall, with a spatial resolution\nwell below the grain diameter. For increasing shear, we observe a transition in\nthe system response and the manifestations of anisotropies in the force chains.\nThe employed technique is of easy implementation and is especially suitable for\nthe study of stationary processes."
    },
    {
        "anchor": "Understanding three-body contributions to coarse-grained force-fields: Coarse-graining (CG) is a systematic reduction of the number of degrees of\nfreedom (DOF) used to describe a system of interest. CG can be thought of as a\nprojection on coarse-grained DOF and is therefore dependent on the functions\nused to represent the CG force field. In this work, we show that naive\nextensions of the coarse-grained force-field can result in unphysical\nparametrizations of the CG potential energy surface (PES). This issue can be\nelevated by coarse-graining the two- and three-body forces separately, which\nalso helps to evaluate the importance of many-body interactions for a given\nsystem. The approach is illustrated on liquid water, where three-body\ninteractions are essential to reproduce the structural properties, and liquid\nmethanol, where two-body interactions are sufficient to reproduce the main\nfeatures of the atomistic system.",
        "positive": "Anankeon theory and viscosity of liquids: a toy model: A simplistic model, based on the concept of anankeon, is proposed to predict\nthe value of the viscosity of a material in its liquid phase. As a result,\nwithin the simplifications and hypothesis made to define the model, it is\npossible to predict (a) the existence of a difference between strong and\nfragile liquids, (b) a fast variation of the viscosity near the glass\ntransition temperature for fragile liquids. The model is a mechanical analog of\nthe Drude model for the electric transport in metal."
    },
    {
        "anchor": "Role of structure in the alpha and beta dynamics of a simple\n  glass-forming liquid: The elusive connection between dynamics and local structure in supercooled\nliquids is an important piece of the puzzle in the unsolved problem of the\nglass transition. The Johari-Goldstein beta relaxation, ubiquitous in\nglass-forming liquids, exhibits mean properties that are strongly correlated to\nthe long-time alpha dynamics. However, the former comprises simpler, more\nlocalized motion, and thus has perhaps a more straightforward connection to\nstructure. Molecular dynamics simulations were carried out on a\ntwo-dimensional, rigid diatomic molecule (the simplest structure exhibiting a\ndistinct beta process) to assess the role of the local liquid structure on both\nthe Johari-Goldstein beta and the alpha relaxation. Although the average\nproperties for these two relaxations are correlated, there is no connection\nbetween the beta and alpha properties of a given (single) molecule. The\npropensity for motion at long times is independent of the rate or strength of a\nmolecule's beta relaxation. The mobility of a molecule averaged over many\ninitial energies, a measure of the influence of structure, was found to be\nheterogeneous, with clustering at both the beta and alpha timescales. This\nheterogeneity is less extended spatially for the beta than for the alpha\ndynamics, as expected; however, the local structure is the more dominant\ncontrol parameter for the beta prcoess. In the glassy state, the arrangement of\nneighboring molecules determines entirely the relaxation properties, with no\ndiscernible effect from the particle momenta.",
        "positive": "Theory of Interfacial Tension of Partially Miscible Liquids: The aim of this work is to study the problem of the existence of a\nfundamental relation between the interfacial tension of a system of two\npartially miscible liquids and the surface tensions of the pure substances. It\nis shown that these properties cannot be correlated from the physical point of\nview. However, an accurate relation between them may be developed using a\nmathematical artifact. In the light of this work, the basis of the empirical\nformula of Girifalco and Good is examined. The weakness of this formula as well\nas the approximation leading to it are exposed and discussed and, a new\nequation connecting interfacial and surface tensions is proposed."
    },
    {
        "anchor": "Spinodal decomposition of off-critical quenches with a viscous phase\n  using dissipative particle dynamics in two and three spatial dimensions: We investigate the domain growth and phase separation of\nhydrodynamically-correct binary immiscible fluids of differing viscosity as a\nfunction of minority phase concentration in both two and three spatial\ndimensions using dissipative particle dynamics. We also examine the behavior of\nequal-viscosity fluids and compare our results to similar lattice-gas\nsimulations in two dimensions.",
        "positive": "Dynamical Scaling and Phase Coexistence in Topologically-Constrained DNA\n  Melting: There is a long-standing experimental observation that the melting of\ntopologically constrained DNA, such as circular-closed plasmids, is less abrupt\nthan that of linear molecules. This finding points to an intriguing role of\ntopology in the physics of DNA denaturation, which is however poorly\nunderstood. Here, we shed light on this issue by combining large-scale Brownian\nDynamics simulations with an analytically solvable phenomenological Landau mean\nfield theory. We find that the competition between melting and supercoiling\nleads to phase coexistence of denatured and intact phases at the single\nmolecule level. This coexistence occurs in a wide temperature range, thereby\naccounting for the broadening of the transition. Finally, our simulations show\nan intriguing topology-dependent scaling law governing the growth of\ndenaturation bubbles in supercoiled plasmids, which can be understood within\nthe proposed mean field theory."
    },
    {
        "anchor": "Entry of Microparticles into Giant Lipid Vesicles by Optical Tweezers: Entry of micro- or nano-sized objects into cells or vesicles made of lipid\nmembranes occur in many processes such as entry of viruses in host cells,\nmicroplastics pollution, drug delivery or biomedical imaging. Here, we\ninvestigated the microparticle crossing of lipid membranes in giant unilamellar\nvesicles in the absence of strong binding interactions (e.g.\nstreptavidin-biotin binding). In these conditions, we observed that organic and\ninorganic particles can always penetrate inside the vesicles provided that an\nexternal picoNewton force is applied and for relatively low membrane tensions.\nIn the limit of a vanishing adhesion, we pointed out the role of the membrane\narea reservoir and show that a force minimum exists when the particle size is\ncomparable to the bendocapillary length.",
        "positive": "Propagation of Rarefaction Pulses in Discrete Materials with\n  Strain-Softening Behavior: Discrete materials composed of masses connected by strongly nonlinear links\nwith anomalous behavior (reduction of elastic modulus with strain) have very\ninteresting wave dynamics. Such links may be composed of materials exhibiting\nrepeatable softening behavior under loading and unloading. These discrete\nmaterials will not support strongly nonlinear compression pulses due to\nnonlinear dispersion but may support stationary rarefaction pulses or\nrarefaction shock-like waves. Here we investigate rarefaction waves in\nnonlinear periodic systems with a general power-law relationship between force\nand displacement $F \\propto \\delta^{n}$, where $0 < n < 1$. An exact solution\nof the long-wave approximation is found for the special case of $n = 1/2$,\nwhich agrees well with numerical results for the discrete chain. Theoretical\nand numerical analysis of stationary solutions are discussed for different\nvalues of $n$ in the interval $0 < n < 1$. The leading solitary rarefaction\nwave followed by a dispersive tail was generated by impact in numerical\ncalculations."
    },
    {
        "anchor": "Gelation and Re-entrance in Mixtures of Soft Colloids and Linear\n  Polymers of Equal Size: Liquid mixtures composed of colloidal particles and much smaller\nnon-adsorbing linear homopolymers can undergo a gelation transition due to\npolymer-mediated depletion forces. We now show that the addition of linear\npolymers to suspensions of soft colloids having the same hydrodynamic size\nyields a liquid-to-gel-to-re-entrant liquid transition. In particular, the\ndynamic state diagram of 1,4-polybutadiene star-linear polymer mixtures was\ndetermined with the help of linear viscoelastic and small angle X-ray\nscattering experiments. While keeping the star polymers below their nominal\noverlap concentration, a gel was formed upon increasing the linear polymer\ncontent. Further addition of linear chains yielded a re-entrant liquid. This\nunexpected behavior was rationalized by the interplay of three possible\nphenomena: (i) depletion interactions, driven by the size disparity between the\nstars and the polymer length scale which is the mesh size of this entanglement\nnetwork; (ii) colloidal deswelling due to the increased osmotic pressure\nexerted onto the stars; and (iii) a concomitant progressive suppression of\ndepletion efficiency on increasing polymer concentration due to reduced mesh\nsize, hence a smaller range of attraction. Our results unveil an exciting new\nway to tailor the flow of soft colloids and highlight a largely unexplored path\nto engineer soft colloidal mixtures.",
        "positive": "Emergent vortices in populations of colloidal rollers: Coherent vortical motion has been reported in a wide variety of populations\nincluding living organisms (bacteria, fishes, human crowds) and synthetic\nactive matter (shaken grains, mixtures of biopolymers), yet a unified\ndescription of the formation and structure of this pattern remains lacking.\nHere we report the self-organization of motile colloids into a macroscopic\nsteadily rotating vortex. Combining physical experiments and numerical\nsimulations, we elucidate this collective behavior. We demonstrate that the\nemergent-vortex structure lives on the verge of a phase separation, and single\nout the very constituents responsible for this state of polar active matter.\nBuilding on this observation, we establish a continuum theory and lay out a\nstrong foundation for the description of vortical collective motion in a broad\nclass of motile populations constrained by geometrical boundaries."
    },
    {
        "anchor": "Zonal flows and reversals of cortically confined active suspensions: At sufficiently high concentrations, motile bacteria suspended in fluids\nexhibit a range of ordered and disordered collective motions. Here we explore\nthe combined effects of confinement, periodicity and curvature induced by the\nactive motion of E. coli bacteria in a thin spherical shell (cortex) of an\noil-water-oil (O/B/O) double emulsion drop. Confocal microscopy of the\nbacterial flow fields shows that at high density and activity, they exhibit\nazimuthal zonal flows which oscillate between counterclockwise and clockwise\ncirculating states. We characterize these oscillatory patterns via their\nFourier spectra and the distributions of their circulation persistence times.\nTo explain our observations, we used numerical simulations of active particles\nand characterize the two-dimensional phase space of bacterial packing fraction\nand activity associated with persistent collective motions. All together, our\nstudy shows how geometric effects lead to new types of collective dynamics.",
        "positive": "Dynamics of wet granular hexagons: The collective behavior of vibrated hexagonal disks confined in a monolayer\nis investigated experimentally. Due to the broken circular symmetry, hexagons\nprefer to rotate upon sufficiently strong driving. Due to the formation of\nliquid bridges, short-ranged cohesive interactions are introduced upon wetting.\nConsequently, a nonequilibrium stationary state with the rotating disks\nself-organized in a hexagonal structure arises. The bond length of the\nhexagonal structure is slightly smaller than the circumdiameter of a hexagon,\nindicating geometric frustration. This investigation provides an example where\nthe collective behavior of granular matter is tuned by the shape of individual\nparticles."
    },
    {
        "anchor": "Machine-learning free-energy functionals using density profiles from\n  simulations: The formally exact framework of equilibrium Density Functional Theory (DFT)\nis capable of simultaneously and consistently describing thermodynamic and\nstructural properties of interacting many-body systems in arbitrary external\npotentials. In practice, however, DFT hinges on approximate (free-)energy\nfunctionals from which density profiles (and hence the thermodynamic potential)\nfollow via an Euler-Lagrange equation. Here we explore a relatively simple\nMachine Learning (ML) approach to improve the standard mean-field approximation\nof the excess Helmholtz free energy functional of a 3D Lennard-Jones system at\na supercritical temperature. The learning set consists of density profiles from\ngrand-canonical Monte Carlo simulations of this system at varying chemical\npotentials and external potentials in a planar geometry only. Using the DFT\nformalism we nevertheless can extract not only very accurate 3D bulk equations\nof state but also radial distribution functions using the Percus test-particle\nmethod. Unfortunately, our ML approach did not provide very reliable\nOrnstein-Zernike direct correlation functions for small distances.",
        "positive": "Phase transitions in single macromolecules: loop-stretch transition\n  versus loop adsorption transition in end-grafted polymer chains: We use Brownian dynamics simulations and analytical theory to compare two\nprominent types of single molecule transitions. One is the adsorption\ntransition of a loop (a chain with two ends bound to an attractive substrate)\ndriven by an attraction parameter $\\varepsilon$, and the other is the\nloop-stretch transition in a chain with one end attached to a repulsive\nsubstrate, driven by an external end-force $F$ applied to the free end.\nSpecifically, we compare the behavior of the respective order parameters of the\ntransitions, i.e., the mean number of surface contacts in the case of the\nadsorption transition, and the mean position of the chain end in the case of\nthe loop-stretch transition. Close to the transition points, both the static\nand the dynamic behavior of chains with different length $N$ are very well\ndescribed by a scaling Ansatz with the scaling parameters $(\\varepsilon -\n\\varepsilon^*) N^\\phi$ (adsorption transition) and $(F-F^*) N^\\nu$\n(loop-stretch transition), respectively, where $\\phi$ is the crossover exponent\nof the adsorption transition, and $\\nu$ the Flory exponent. We show that both\nthe loop-stretch and the loop adsorption transitions provide an exceptional\nopportunity to construct explicit analytical expressions for the crossover\nfunctions which perfectly describe all simulation results on static properties\nin the finite-size scaling regime. Explicit crossover functions are based on\nthe Ansatz for the analytical form of the order parameter distributions at the\nrespective transition points. In contrast to the close similarity in\nequilibrium static behavior, the dynamic relaxation at the two transitions\nshows qualitative differences, especially in the strongly ordered regimes."
    },
    {
        "anchor": "Instabilities and geometry of growing tissues: We derive a course grained, continuum model of the 2D vertex model,\napplicable for different underlying geometries, and allowing for analytical\nanalysis of an otherwise numerical model. Using a geometric approach and\nout--of--equilibrium statistical mechanics, we calculate both mechanical and\ndynamical instabilities within a tissue, and their dependence on different\nvariables, including activity, and disorder. Most notably, the tissue's\nresponse depends on the existence of mechanical residual stresses in the\ntissue. Thus, even freely growing tissues may exhibit a growth instability\ndepending on food consumption. Using this geometric model we can readily\ndistinct between elasticity and plasticity in a growing, flowing, tissue.",
        "positive": "Microscopic and macroscopic compaction of cohesive powders: A novel method to investigate the compaction behaviour of cohesive powders is\npresented. As a sample, a highly porous agglomerate formed by random ballistic\ndeposition (RBD) of micron sized spherical particles is used. A nanomanipulator\ndeforms this small structure under scanning electron microscope observation,\nallowing for the tracking of individual particle motion. Defined forces are\napplied and the resulting deformations are measured. The hereby obtained\nresults are compared to results from threedimensional discrete element\nsimulations as well as macroscopic compaction experiments. Relevant simulation\nparameters are determined by colloidal probe measurements."
    },
    {
        "anchor": "'Flow & Jam' of frictional athermal systems under shear stress: We report recent results of molecular dynamics simulations of frictional\nathermal particles at constant volume fraction and constant applied shear\nstress, focusing on a range of control parameters where the system first flows,\nbut then jams after a time tjam. On decreasing the volume fraction, the mean\njamming time diverges, while its sample fluctuations become so large that the\njamming time probability distribution P(tjam) becomes a power-law. We obtain an\ninsight on the origin of this phenomenology focusing on the flowing regime,\nwhich is characterized by the presence of a clear correlation between the shear\nvelocity and the mean number of contacts per particles Z, whereby small\nvelocities occur when Z acquires higher values.",
        "positive": "The Dielectric Constant of Ionic Solutions: A Field-Theory Approach: We study the variation of the dielectric response of a dielectric liquid\n(e.g. water) when a salt is added to the solution. Employing field-theoretical\nmethods we expand the Gibbs free-energy to first order in a loop expansion and\ncalculate self-consistently the dielectric constant. We predict analytically\nthe dielectric decrement which depends on the ionic strength in a complex way.\nFurthermore, a qualitative description of the hydration shell is found and is\ncharacterized by a single length scale. Our prediction fits rather well a large\nrange of concentrations for different salts using only one fit parameter\nrelated to the size of ions and dipoles."
    },
    {
        "anchor": "Efficient structural color from pigment-loaded nanostructures: Color can originate from wavelength-dependence in the absorption of pigments\nor the scattering of nanostructures. While synthetic colors are dominated by\nthe former, vivid structural colors found in nature have inspired much research\non the latter. However, many of the most vibrant colors in nature involve the\ninteractions of structure and pigment. Here, we demonstrate that pigment can be\nexploited to efficiently create bright structural color at wavelengths outside\nits absorption band. We created pigment-enhanced Bragg reflectors by\nsequentially spin-coating layers of poly-vinyl alcohol (PVA) and polystyrene\n(PS) loaded with $\\beta$-carotene (BC). With only 10 double layers, we acheived\na peak reflectance over $0.8$ at 550 nm and normal incidence. A pigment-free\nmultilayer made of the same materials would require 25 double layers to achieve\nthe same reflectance. Further, pigment loading suppressed the Bragg reflector's\ncharacteristic iridescence. Using numerical simulations, we further show that\nsimilar pigment loadings could significantly expand the gamut of non-iridescent\ncolors addressable by photonic glasses.",
        "positive": "Following microscopic motion in a two dimensional glass-forming binary\n  fluid: The dynamics of a binary mixture of large and small discs are studied at\ntemperatures approaching the glass transition using an analysis based on the\ntopology of the Voronoi polygon surrounding each atom. At higher temperatures\nwe find that dynamics is dominated by fluid-like motion that involves particles\nentering and exiting the nearest-neighbour shells of nearby particles. As the\ntemperature is lowered, the rate of topological moves decreases and motion\nbecomes localised to regions of mixed pentagons and heptagons. In addition we\nfind that in the low temperature state particles may translate significant\ndistances without undergoing changes in their nearest neig hbour shell. These\nresults have implications for dynamical heterogeneities in glass forming\nliquids."
    },
    {
        "anchor": "Tensor Electromagnetism and Emergent Elasticity in Jammed Solids: The theory of mechanical response and stress transmission in disordered,\njammed solids poses several open questions of how non-periodic networks --\napparently indistinguishable from a snapshot of a fluid -- sustain shear. We\npresent a stress-only theory of emergent elasticity for a non-thermal amorphous\nassembly of grains in a jammed solid, where each grain is subjected to\nmechanical constraints of force and torque balance. These grain-level\nconstraints lead to the Gauss's law of an emergent $U(1)$ tensor\nelectromagnetism, which then accounts for the mechanical response of such\nsolids. This formulation of amorphous elasticity has several immediate\nconsequences. The mechanical response maps exactly to the static, dielectric\nresponse of this tensorial electromagnetism with the polarizability of the\nmedium mapping to emergent elastic moduli. External forces act as vector\nelectric charges whereas the tensorial magnetic fields are sourced by momentum\ndensity. The dynamics in the electric and magnetic sectors, naturally translate\ninto the dynamics of the rigid jammed network and ballistic particle motion\nrespectively. The theoretical predictions for both stress-stress correlations\nand responses are borne out by the results of numerical simulations of\nfrictionless granular packings in the static limit of the theory in both 2D and\n3D.",
        "positive": "Spectral Analysis of Inhomogeneities Shows that the Elastic Stiffness of\n  Random Composites Decreases with Increasing Heterogeneity: Investigation of inhomogeneities has wide applications in different areas of\nmechanics including the study of composite materials. Here, we analytically\nstudy an arbitrarily-shaped isotropic inhomogeneity embedded in a finite-sized\nheterogeneous medium. By modal decomposition of the influence of the\ninhomogeneity on the deformation of the composite, a relation is presented that\ndetermines the variation of effective elastic stiffness caused by the presence\nof the inhomogeneity. This relation indicates that the effective elastic\nstiffness of a composite is always a concave function of the properties of the\ninhomogeneity, embedded inside the composite. Therefore, as the heterogeneity\nof elastic random composites increases, the rate of increase in effective\nstiffness caused by the stiffer constituents is smaller than the rate of its\ndecrease due to the softer constitutions. So, weakly heterogeneous random\ncomposites become softer and less conductive with increasing heterogeneity at\nthe same mean of constituent properties. We numerically evaluated the effective\nproperties of about ten thousand composites to empirically support these\nresults and extend them to conductive materials. This article presents a\ngeneralization of our recent theoretical study on the influence of the\nstiffness of a single fiber on the elastic stiffness of a network of fibers to\narbitrarily-shaped inhomogeneities and different transport phenomena."
    },
    {
        "anchor": "Lattice-Boltzmann Model of Amphiphilic Systems: A lattice-Boltzmann model for the study of the dynamics of\noil-water-surfactant mixtures is constructed. The model, which is based on a\nGinzburg-Landau theory of amphiphilic systems with a single, scalar order\nparameter, is then used to calculate the spectrum of undulation modes of an\noil-water interface and the spontaneous emulsification of oil and water after a\nquench from two-phase coexistence into the lamellar phase. A comparison with\nsome analytical results shows that the model provides an accurate description\nof the static and dynamic behavior of amphiphilic systems.",
        "positive": "Ordered Phases of Diblock Copolymer Micelles in Selective Solvent: We propose a mean-field model to explore the equilibrium coupling between\nmicelle aggregation and lattice choice in neutral copolymer and selective\nsolvent mixtures. We find both thermotropic and lyotropic transitions from\nface-centered cubic to body-centered cubic ordered phases of spherical\nmicelles, in agreement with experimental observations of these systems over a\nbroad range of conditions. Stability of the non-closed packed phase can be\nattributed to two physical mechanisms: the large entropy of lattice phonons\nnear crystal melting and the preference of the inter-micelle repulsions for the\nbody-centered cubic structure when the lattice becomes sufficiently dense at\nhigher solution concentrations. Both mechanisms are controlled by the decrease\nof micelle aggregation and subsequent increase of lattice density as solvent\nselectivity is reduced. These results shed new light on the relationship\nbetween micelle structure -- \"crewcut\" or \"hairy\" -- and long-range order in\nmicelle solutions."
    },
    {
        "anchor": "Fracture Toughness and Maximum Stress in a Disordered Lattice System: Fracture in a disordered lattice system is studied. In our system, particles\nare initially arranged on the triangular lattice and each nearest-neighbor pair\nis connected with a randomly chosen soft or hard Hookean spring. Every spring\nhas the common threshold of stress at which it is cut. We make an initial crack\nand expand the system perpendicularly to the crack. We find that the maximum\nstress in the stress-strain curve is larger than those in the systems with soft\nor hard springs only (uniform systems). Energy required to advance fracture is\nalso larger in some disordered systems, which indicates that the fracture\ntoughness improves. The increase of the energy is caused by the following two\nfactors. One is that the soft spring is able to hold larger energy than the\nhard one. The other is that the number of cut springs increases as the fracture\nsurface becomes tortuous in disordered systems.",
        "positive": "Nonlinear Dynamics of Spherical Shells Buckling under Step Pressure: Dynamic buckling is addressed for complete elastic spherical shells subject\nto a rapidly applied step in external pressure. Insights from the perspective\nof nonlinear dynamics reveal essential mathematical features of the buckling\nphenomena. To capture the strong buckling imperfection-sensitivity, initial\ngeometric imperfections in the form of an axisymmetric dimple at each pole are\nintroduced. Dynamic buckling under the step pressure is related to the\nquasi-static buckling pressure. Both loadings produce catastrophic collapse of\nthe shell for conditions in which the pressure is prescribed. Damping plays an\nimportant role in dynamic buckling because of the time-dependent nonlinear\ninteraction among modes, particularly the interaction between the spherically\nsymmetric 'breathing' mode and the buckling mode. In this paper we argue that\nthe precise frequency dependence of the damping does not matter as most of the\ndamping happens at a single frequency (the breathing frequency). In general,\nthere is not a unique step pressure threshold separating responses associated\nwith buckling from those that do not buckle. Instead there exists a cascade of\nbuckling thresholds, dependent on the damping and level of imperfection,\nseparating pressures for which buckling occurs from those for which it does not\noccur. For shells with small and moderately small imperfections the dynamic\nstep buckling pressure can be substantially below the quasi-static buckling\npressure."
    },
    {
        "anchor": "Hidden complexities in the unfolding mechanism of a cytosine-rich DNA\n  strand: We investigate the unfolding pathway of a cytosine-rich DNA hairpin structure\nvia Molecular Dynamics simulations. Our results indicate a hidden complexity\npresent in the unfolding process. W e show that this complex behavior arises\ndue to non-stochastic contributions which have an important impact on the\ndescription of the dynamics in terms of collective variables.",
        "positive": "Torque-Induced Rotational Dynamics in Polymers: Torsional Blobs and\n  Thinning: By using the blob theory and computer simulations, we investigate the\nproperties of a linear polymer performing a stationary rotational motion around\na long impenetrable rod. In particular, in the simulations the rotation is\ninduced by a torque applied to the end of the polymer that is tethered to the\nrod. Three different regimes are found, in close analogy with the case of\npolymers pulled by a constant force at one end. For low torques the polymer\nrotates maintaining its equilibrium conformation. At intermediate torques the\npolymer assumes a trumpet shape, being composed by blobs of increasing size. At\neven larger torques the polymer is partially wrapped around the rod. We derive\nseveral scaling relations between various quantities as angular velocity,\nelongation and torque. The analytical predictions match the simulation data\nwell. Interestingly, we find a \"thinning\" regime where the torque has a very\nweak (logarithmic) dependence on the angular velocity. We discuss the origin of\nthis behavior, which has no counterpart in polymers pulled by an applied force."
    },
    {
        "anchor": "Plastic Deformation of 2D Crumpled Wires: When a single long piece of elastic wire is injected trough channels into a\nconfining two-dimensional cavity, a complex structure of hierarchical loops is\nformed. In the limit of maximum packing density, these structures are described\nby several scaling laws. In this paper it is investigated this packing process\nbut using plastic wires which give origin to completely irreversible structures\nof different morphology. In particular, it is studied experimentally the\nplastic deformation from circular to oblate configurations of crumpled wires,\nobtained by the application of an axial strain. Among other things, it is shown\nthat in spite of plasticity, irreversibility, and very large deformations,\nscaling is still observed.",
        "positive": "Virial series for inhomogeneous fluids applied to the Lennard-Jones\n  wall-fluid surface tension at planar and curved walls: We formulate a straightforward scheme of statistical mechanics for\ninhomogeneous systems that includes the virial series in powers of the activity\nfor the grand free energy and density distributions. There, cluster integrals\nformulated for inhomogeneous systems play a main role. We center on second\norder terms that were analyzed in the case of hard-wall confinement, focusing\nin planar, spherical and cylindrical walls. Further analysis was devoted to the\nLennard-Jones system and its generalization the 2k-k potential. For this\ninteraction potentials the second cluster integral was evaluated analytically.\nWe obtained the fluid-substrate surface tension at second order for the planar,\nspherical and cylindrical confinement. Spherical and cylindrical cases were\nanalyzed using a series expansion in the radius including higher order terms.\nWe detected a $\\ln R^{-1}/R^{2}$ dependence of the surface tension for the\nstandard Lennard-Jones system confined by spherical and cylindrical walls, no\nmatter if particles are inside or outside of the hard-walls. The analysis was\nextended to bending and Gaussian curvatures, where exact expressions were also\nobtained."
    },
    {
        "anchor": "Computer simulation of three dimensional shearing of granular materials:\n  Formation of shear bands: We used computer simulations to study spontaneous strain localization in\ngranular materials, as a result of symmetry breaking non-homogeneous\ndeformations. Axisymmetric triaxial shear tests were simulated by means of\nstandard three-dimensional Distinct Element Method (DEM) with spherical grains.\nCarefully prepared dense specimens were compressed between two platens and, in\norder to mimic the experimental conditions, stress controlled, (initially)\naxisymmetric boundary conditions were constructed. Strain localization gave\nrise to visible shear bands, previously found experimentally under similar\nconditions by several groups, and different morphologies could be reproduced.\nWe examined the stress-strain relation during the process and found good\nagreement with experiments. Formation mechanism of shear bands is discussed.",
        "positive": "Theory of rheology in confinement: The viscosity of fluids is generally understood in terms of kinetic\nmechanisms, i.e., particle collisions, or thermodynamic ones as imposed through\nstructural distortions upon e.g. applying shear. Often the former is less\nrelevant, and (damped) Brownian particles are considered good fluid model\nsystems. We formulate a general theoretical approach for rheology in\nconfinement, based on the many particle diffusion equation, evaluated via\nclassical density functional theory. We discuss the viscosity for the situation\nof two parallel walls in relative motion as a function of wall-to-wall\ndistance."
    },
    {
        "anchor": "Ion Solvation in Dipolar Poisson models in a dual view: We study the classic problem of ion solvation within the continuum theory of\nDipolar-Poisson models. In this approach an ion is treated as a point charge\nwithin a sea of point dipoles. Both the standard Dipolar-Poisson model as well\nas the Dipolar-Poisson-Langevin model, which keeps the dipolar density fixed,\nare non-convex functionals of the scalar electrostatic potential $\\phi$.\nApplying the Legendre transform approach introduced by A.C. Maggs [A.C. Maggs,\nEurophys. Lett. 98, 16012 (2012)], the dual functionals of these models are\nderived and are given by convex vector-field functionals of the dielectric\ndisplacement and the polarization field. We show that the\nDipolar-Poisson-Langevin functional generalizes the harmonic polarization\nfunctional used in the theory of Marcus for electron transfer rate to nonlinear\nregimes and can be quantitatively parametrized by molecular dynamics\nsimulations for SPC/E-water.",
        "positive": "Free-energy landscapes and insertion pathways for peptides in membrane\n  environment: Free-energy landscapes for short peptides -- specifically for variants of the\npH Low Insertion Peptide (pHLIP) -- in the heterogeneous environment of a lipid\nbilayer or cell membrane are constructed, taking into account a set of dominant\ninteractions and the conformational preferences of the peptide backbone. Our\nmethodology interprets broken internal H-bonds along the backbone of a\npolypeptide as statistically interacting quasiparticles, activated from the\nhelix reference state. The favored conformation depends on the local\nenvironment (ranging from polar to nonpolar), specifically on the availability\nof external H-bonds (with $\\mathrm{H_2O}$ molecules or lipid headgroups) to\nreplace internal H-bonds. The dominant side-chain contribution is accounted for\nby residue-specific transfer free energies between polar and nonpolar\nenvironments. The free-energy landscape is sensitive to the level of pH in the\naqueous environment surrounding the membrane. For high pH, we identify pathways\nof descending free energy that suggest a coexistence of membrane-adsorbed\npeptides with peptides in solution. A drop in pH raises the degree of\nprotonation of negatively charged residues and thus increases the\nhydrophobicity of peptide segments near the C terminus. For low pH, we identify\ninsertion pathways between the membrane-adsorbed state and a stable\ntrans-membrane state with the C terminus having crossed the membrane."
    },
    {
        "anchor": "Dynamics of a Liquid Crystal close to the Fr\u00e9edericksz transition: We report experimental and numerical evidences that the dynamics of the\ndirector of a liquid crystal driven by an electric field close to the critical\npoint of the Fr\\'eedericksz Transition(FT) is not described by a\nLandau-Ginzburg (LG) equation as it is usually done in literature. The reasons\nare related to the very crude approximations done to obtain this equation, to\nthe finite value of the anchoring energy and to small asymmetries on boundary\nconditions. We also discuss the difference between the use of LG equation for\nthe statics and the dynamics. These results are useful in all cases where FT is\nused as an example for other orientational transitions.",
        "positive": "Screening by symmetry of long-range hydrodynamic interactions of\n  polymers confined in sheets: Hydrodynamic forces may significantly affect the motion of polymers. In\nsheet-like cavities, such as the cell's cytoplasm and microfluidic channels,\nthe hydrodynamic forces are long-range. It is therefore expected that that\nhydrodynamic interactions will dominate the motion of polymers in sheets and\nwill be manifested by Zimm-like scaling. Quite the opposite, we note here that\nalthough the hydrodynamic forces are long-range their overall effect on the\nmotion of polymers vanishes due to the symmetry of the two-dimensional flow. As\na result, the predicted scaling of experimental observables such as the\ndiffusion coefficient or the rotational diffusion time is Rouse-like, in accord\nwith recent experiments. The effective screening validates the use of the\nnon-interacting blobs picture for polymers confined in a sheet."
    },
    {
        "anchor": "Strong and Highly Switchable Soft Sticky Adhesives: Many biological systems can form strong adhesion to various materials with\ncomplex shapes. The adhesion is further switchable between strongly adhering\nand completely non-adhering in a simple and fast manner. By contrast, no\nengineering system has yet achieved the same robust adherence and switching.\nThis limitation severely hinders the advancement of several emerging\ntechnologies including biomimetic robots, assembly-based manufacturing,\nprecision medicine, wearable and implantable devices, as well as on-demand\nmaterial dismantling and recycling for sustainability. Here we present a design\napproach for strong and highly switchable adhesion by synergizing the surface\nstickiness, bulk energy dissipation, and stimuli-responsive polymer chains in a\nthermo-switchable soft sticky adhesive. The adhesive has a high adhesion\nstrength of about 80 kPa with diverse materials at room temperature. The\nadhesion is highly switchable to near-vanishing (about 0.6 kPa) at an elevated\ntemperature due to the thermo-responsive surface polymer chain retraction. This\nadhesion switching is reversible and repeatable for many cycles, enabling\nselective pick-and-release of objects with various materials, shapes, sizes,\nand weights. The switching time is around 10 s with an adhesive layer of 1 mm,\ngoverned by thermal conduction through the adhesive, faster than or comparable\nto most state-of-the-art methods. The adhesive is self-healing, and can be\nrecycled, dried, stored, reswollen, and reused with nearly intact adhesion and\nswitching properties. The synergistic design combining strong adhesion and\nstimuli-responsive switching can be potentially extended to various polymer\nsystems, and further enhanced by optimized surface architectures.",
        "positive": "Experimental growth law for bubbles in a \"wet\" 3D liquid foam: We used X-ray tomography to characterize the geometry of all bubbles in a\nliquid foam of average liquid fraction $\\phi_l\\approx 17 %$ and to follow their\nevolution, measuring the normalized growth rate\n$\\mathcal{G}=V^{-{1/3}}\\frac{dV} {dt}$ for 7000 bubbles. While $\\mathcal{G}$\ndoes not depend only on the number of faces of a bubble, its average over\n$f-$faced bubbles scales as $G_f\\sim f-f_0$ for large $f$s at all times. We\ndiscuss the dispersion of $\\mathcal{G}$ and the influence of $V$ on\n$\\mathcal{G}$."
    },
    {
        "anchor": "Experimental velocity fields and forces for a cylinder penetrating into\n  a granular medium: We present here a detailed granular flow characterization together with force\nmeasurements for the quasi-bidimensional situation of a horizontal cylinder\npenetrating vertically at a constant velocity in dry granular matter between\ntwo parallel glass walls. In the velocity range studied here, the drag force on\nthe cylinder does not depend on the velocity V_0 and is mainly proportional to\nthe cylinder diameter d. Whereas the force on the cylinder increases with its\npenetration depth, the granular velocity profile around the cylinder is found\nstationary with fluctuations around a mean value leading to the granular\ntemperature profile. Both mean velocity profile and temperature profile exhibit\nstrong localization near the cylinder. The mean flow perturbation induced by\nthe cylinder decreases exponentially away from the cylinder on a characteristic\nlength \\lambda, that is mainly governed by the cylinder diameter for large\nenough cylinder/grain size ratio d/d_g: \\lambda ~ d/4 + 2d_g. The granular\ntemperature exhibits a constant plateau value T_0 in a thin layer close to the\ncylinder of extension \\delta_{T_0} ~ \\lambda/2 and decays exponentially far\naway with a characteristic length \\lambda_T of a few grain diameters (\\lambda_T\n~ 3d_g). The granular temperature plateau T_0 that scales as (V_0^2 d_g/d) is\ncreated by the flow itself from the balance between the \"granular heat\"\nproduction by the shear rate V_0/\\lambda over \\delta_{T_0} close to the\ncylinder and the granular dissipation far away.",
        "positive": "Defect-driven shape transitions in elastic active nematic shells: Active matter is characterized by its ability to induce motion by\nself-generated stress. In the case of a solid, such motion can lead to shape\ntransformations. The stress-generating components can be anisotropic endowing\nthe material with mesoscopic orientational order. It is currently unknown how\nthe specific postions and orientations of these active constituents influence\nmorphological changes. We study theoretically the effects of imposing\ntopological point defects in the arrangements of the stress-generating\ncomponents on the morphology of elastic active nematic shells. We show that\ntopological defects of charge +1 are uniquely capable of increasing, reducing\nor maintaining the intrinsic curvature of the shell. These changes depend on\nthe nature of the active stress and the phase angle of the defect. We apply our\ntheory to experiments conducted on contracting actomyosin sheets. By combining\ndefects of different charges, we can generate shells with arbitrary complexity.\nWe confirm this flexibility by reproducing the shape of the freshwater polyp\nHydra, in which topological defects have been associated with morphological\nfeatures of the animal. In addition to understanding morphogenetic processes,\nthese principles can be applied to the design of programmable active mechanical\nmetamaterials that form the basis of autonomous soft robots."
    },
    {
        "anchor": "Fracture of granular materials composed of arbitrary grain shapes: A new\n  cohesive interaction model: Discrete Element Methods (DEM) are a useful tool to model the fracture of\ncohesive granular materials. For this kind of application, simple particle\nshapes (discs in 2D, spheres in 3D) are usually employed. However, dealing with\nmore general particle shapes allows to account for the natural heterogeneity of\ngrains inside real materials. We present a discrete model allowing to mimic\ncohesion between contacting or non-contacting particles whatever their shape in\n2D and 3D. The cohesive interactions are made of cohesion points placed on\ninteracting particles, with the aim of representing a cohesive phase lying\nbetween the grains. Contact situations are solved according to unilateral\ncontact and Coulomb friction laws. In order to test the developed model, 2D\nunixial compression simulations are performed. Numerical results show the\nability of the model to mimic the macroscopic behavior of an aggregate grain\nsubject to axial compression, as well as fracture initiation and propagation. A\nstudy of the influence of model and sample parameters provides important\ninformation on the ability of the model to reproduce various behaviors.",
        "positive": "Brittle and Non-Brittle Events in a Continuum-Granular Earthquake\n  Experiment: We report moment distribution results from a laboratory earthquake fault\nexperiment consisting of sheared elastic plates separated by a narrow gap\nfilled with a two dimensional granular medium. Local measurement of strain\ndisplacements of the plates at over 800 spatial points located adjacent to the\ngap allows direct determination of the moments and their spatial and temporal\ndistributions. We show that events consist of localized, larger brittle motions\nand spatially-extended, smaller non-brittle events. The non-brittle events have\na probability distribution of event moment consistent with an $M^{-3/2}$ power\nlaw scaling. Brittle events have a broad, peaked moment distribution and a mean\nrepetition time. As the applied normal force increases, there are more brittle\nevents, and the brittle moment distribution broadens. Our results are\nconsistent with mean field descriptions of statistical models of earthquakes\nand avalanches."
    },
    {
        "anchor": "Langevin equation of collective modes of Bose-Einstein condensates in\n  traps: A quantum Langevin equation for the amplitudes of the collective modes in\nBose-Einstein condensate is derived. The collective modes are coupled to a\nthermal reservoir of quasi-particles, whose elimination leads to the quantum\nLangevin equation. The dissipation rates are determined via the correlation\nfunction of the fluctuating force and are evaluated in the local-density\napproximation for the spectrum of quasi-particles and the Thomas-Fermi\napproximation for the condensate. I take great pleasure in dedicating this\npaper to Gregoire Nicolis on the occasion of his sixtieth birthday.",
        "positive": "Microscopic Theory of Protein Folding Rates.II: Local Reaction\n  Coordinates and Chain Dynamics: The motion involved in barrier crossing for protein folding are investigated\nin terms of the chain dynamics of the polymer backbone, completing the\nmicroscopic description of protein folding presented in the previous paper.\nLocal reaction coordinates are identified as collective growth modes of the\nunstable fluctuations about the saddle-points in the free energy surface. The\ndescription of the chain dynamics incorporates internal friction (independent\nof the solvent viscosity) arising from the elementary isomerizations of the\nbackbone dihedral angles. We find that the folding rate depends linearly on the\nsolvent friction for high viscosity, but saturates at low viscosity because of\ninternal friction. For $\\lambda$-repressor, the calculated folding rate\nprefactor, along with the free energy barrier from the variational theory,\ngives a folding rate that agrees well with the experimentally determined rate\nunder highly stabilizing conditions, but the theory predicts too large a\nfolding rate at the transition midpoint. This discrepancy obtained using a\nfairly complete quantitative theory inspires a new set of questions about chain\ndynamics, specifically detailed motions in individual contact formation."
    },
    {
        "anchor": "Single-collision statistics reveal a global mechanism driven by sample\n  history for contact electrification in granular media: Models for same-material contact electrification in granular media often rely\non a local charge-driving parameter whose spatial variations lead to a\nstochastic origin for charge exchange. Measuring the charge transfer from\nindividual granular spheres after contacts with substrates of the same\nmaterial, we find that the charge-driving parameter is global, not local.\nCleaning and baking samples fully resets their charging behavior, which\nindicates the underlying global parameter is not intrinsic to the material, but\nacquired from its history. Charging behavior is randomly and irreversibly\naffected by changes in relative humidity, pointing to a mechanism where\nadsorbates, in particular water, are fundamental to the charge-transfer\nprocess.",
        "positive": "The Generic Unfolding of a Biomimetic Polymer during Force Spectroscopy: With the help of force spectroscopy, several analytical theories aim at\nestimating the rate coefficient of folding for various proteins. Nevertheless,\na chief bottleneck lies in the fact that there is still no perfect consensus on\nhow does a force generally perturb the crystal-coil transition. Consequently,\nthe goal of our work is in clarifying the generic behavior of most proteins in\nforce spectroscopy; in other words, what general signature does an arbitrary\nprotein exhibit for its rate coefficient as a function of the applied force? By\nemploying a biomimetic polymer in molecular simulations, we focus on evaluating\nits respective activation energy for unfolding, while pulling on various pairs\nof its monomers. Above all, we find that in the vicinity of the force-free\nscenario, this activation energy possesses a negative slope and a negative\ncurvature as a function of the applied force. Our work is in line with the most\nrecent theories for unfolding, which suggest that such a signature is expected\nfor most proteins, and thus, we further reiterate that many of the classical\nformulae, that estimate the rate coefficient of the crystal-coil transition,\nare inadequate. Besides, we also present here an analytical expression which\nexperimentalists can use for approximating the activation energy for unfolding;\nimportantly, it is based on measurements for the mean and variance of the\ndistance between the beads which are being pulled. In summary, our work\npresents an interesting view for protein folding in force spectroscopy."
    },
    {
        "anchor": "Transport in polymer-gel composites: Response to a bulk concentration\n  gradient: This paper examines the response of electrolyte-saturated polymer gels,\nembedded with charged spherical inclusions, to a weak gradient of electrolyte\nconcentration. These composites present a model system to study microscale\nelectrokinetic transport processes, and a rigorous theoretical prediction of\nthe bulk properties will benefit novel diagnostic applications. An\nelectrokinetic model was presented in an earlier publication, and the response\nof homogeneous composites to a weak electric field was calculated. In this\nwork, the influence of the inclusions on bulk ion fluxes and the strength of an\nelectric field (or membrane diffusion potential) induced by the bulk\nelectrolyte concentration gradient are computed. Effective ion diffusion\ncoefficients are significantly altered by the inclusions, so--depending on the\ninclusion surface charge or $\\zeta$-potential--asymmetric electrolytes can\nbehave as symmetrical electrolytes, and vice versa. The theory also quantifies\nthe strength of flow driven by concentration-gradient-induced perturbations to\nthe equilibrium diffuse double layers. Similarly to diffusiophoresis, the flow\nmay be either up or down the applied concentration gradient.",
        "positive": "Light-switchable propulsion of active particles with reversible\n  interactions: Active systems such as microorganisms and self-propelled particles show a\nplethora of collective phenomena, including swarming, clustering, and phase\nseparation. Control over the propulsion direction and switchability of the\ninteractions between the individual self-propelled units may open new avenues\nin designing of materials from within. Here, we present a self-propelled\nparticle system, consisting of half-gold coated titania ($\\mathrm{TiO}_2$)\nparticles, in which we can fast and on-demand reverse the propulsion direction,\nby exploiting the different photocatalytic activities on both sides. We\ndemonstrate that the reversal in propulsion direction changes the nature of the\nhydrodynamic interaction from attractive to repulsive and can drive the\nparticle assemblies to undergo both fusion and fission transitions. Moreover,\nwe show these active colloids can act as nucleation sites, and switch rapidly\nthe interactions between active and passive particles, leading to\nreconfigurable assembly and disassembly. Our experiments are qualitatively\ndescribed by a minimal hydrodynamic model."
    },
    {
        "anchor": "Electrokinetic Janus micromotors moving on topographically flat chemical\n  patterns: Ionic and molecular selectivity is considered unique for the nanoscale and\nnot realizable in microfluidics. This is due to the scale-matching problem -- a\ndifficulty to match the dimensions of ions and electrostatic potential\nscreening lengths with the micron-sized confinements. Here, we demonstrate a\nmicroscale realization of the ionic transport processes closely resembling\nthose specific to ionic channels or in nanofluidic junctions, including\nselectivity, guidance through complex geometries and flow focusing. As a model\nsystem, we explore electrokinetic spherical Janus micromotors moving over\ncharged surfaces with a complex spatial charge distribution and without any\ntopographical wall. We discuss peculiarities of the long-range electrostatic\ninteraction on the behavior of the system including interface crossing and\nreflection of positively charged particles from negatively charged interfaces.\nThese results are crucial for understanding the electrokinetic transport of\nbiochemical species under confinement, have the potential to increase the\nprecision of lab-on-chip-based assays, as well as broadening use cases and\ncontrol strategies of nano-/micromachinery.",
        "positive": "Effect of polydispersity and soft interactions on the nematic vs.\n  smectic phase stability in platelet suspensions: We discuss theoretically, using density-functional theory, the phase\nstability of nematic and smectic ordering in a suspension of platelets of the\nsame thickness but with a high polydispersity in diameter, and study the\ninfluence of polydispersity on this stability. The platelets are assumed to\ninteract like hard objects, but additional soft attractive and repulsive\ninteractions, meant to represent the effect of depletion interactions are also\nconsidered. The aspect (diameter to thickness) ratio is taken to be very high,\nin order to model solutions of mineral platelets recently explored\nexperimentally. In this regime a high degree of orientational ordering occurs;\ntherefore the model platelets can be taken as completely parallel and are\namenable to analysis via a fundamental-measure theory. Our focus is on the\nnematic vs. smectic phase interplay, since a high degree of polydispersity in\ndiameter suppresses the formation of the columnar phase. When interactions are\npurely hard, the theory predicts a continuous nematic-to-smectic transition,\nregardless of the degree of diameter polydispersity. However, polydispersity\nenhances the stability of the smectic phase against the nematic phase.\nPredictions for the case where an additional soft interaction is added are\nobtained using mean-field perturbation theory. In the case of the one-component\nfluid, the transition remains continuous for repulsive forces, and the smectic\nphase becomes more stable as the range of the interaction is decreased. The\nopposite behaviour with respect to the range is observed for attractive forces,\nand in fact the transition becomes of first order below a tricritical point.\nAlso, for attractive interactions, nematic demixing appears, with an associated\ncritical point. When platelet polydispersity is introduced the tricritical\ntemperature shifts to very high values."
    },
    {
        "anchor": "A lattice model of hydrophobic interactions: Hydrogen bonding is modeled in terms of virtual exchange of protons between\nwater molecules. A simple lattice model is analyzed, using ideas and techniques\nfrom the theory of correlated electrons in metals. Reasonable parameters\nreproduce observed magnitudes and temperature dependence of the hydrophobic\ninteraction between substitutional impurities and water within this lattice.",
        "positive": "Classification of point-group-symmetric orientational ordering tensors: The concept of symmetry breaking has been a propelling force in understanding\nphases of matter. While rotational symmetry breaking is one of the most\nprevalent examples, the rich landscape of orientational orders breaking the\nrotational symmetries of isotropic space, i.e. $O(3)$, to a three-dimensional\npoint group remain largely unexplored, apart from simple examples such as\nferromagnetic or uniaxial nematic ordering. Here we provide an explicit\nconstruction, utilizing a recently introduced gauge theoretical framework, to\naddress the three-dimensional point-group-symmetric orientational orders on a\ngeneral footing. This unified approach allows us to enlist order parameter\ntensors for all three dimensional point groups. By construction, these tensor\norder parameters are the minimal set of simplest tensors allowed by the\nsymmetries that uniquely characterize the orientational order. We explicitly\ngive these for the point groups $\\{C_n, D_n, T, O, I\\} \\subset SO(3)$ and\n$\\{C_{nv}, S_n, C_{nh}, D_{nh}, D_{nd}, T_h, T_d, O_h, I_h\\}\\subset O(3)$ for\n$n=\\{1,2,3,4,6, \\infty\\}$. This central result may be perceived as a roadmap\nfor identifying exotic orientational orders that may become more and more in\nreach in view of rapid experimental progress in e.g. nano-colloidal systems and\nnovel magnets."
    },
    {
        "anchor": "Unifying description of the vibrational anomalies of amorphous materials: The vibrational density of states $D(\\omega)$ of solids controls their\nthermal and transport properties. In crystals, the low-frequency modes are\nextended phonons distributed in frequency according to Debye's law, $D(\\omega)\n\\propto \\omega^2$. In amorphous solids, phonons are damped, and at low\nfrequency $D(\\omega)$ comprises extended modes in excess over Debye's\nprediction, leading to the so-called boson peak in $D(\\omega)/\\omega^2$ at\n$\\omega_{\\rm bp}$, and quasi-localized (QLMs) ones. Here we show that boson\npeak and phonon attenuation in the Rayleigh scattering regime are related, as\nsuggested by correlated fluctuating elasticity theory (corr-FET), and that\namorphous materials can be described as homogeneous isotropic elastic media\npunctuated by QLMs acting as elastic heterogeneities. Our numerical results\nresolve the conflict between theoretical approaches attributing amorphous\nsolids' vibrational anomalies to elastic disorder and localized defects.",
        "positive": "Swimmer-microrheology: We discuss a locomotion of a three-sphere microswimmer in a viscoelastic\nmedium and propose a new type of active microrheology. We derive a relation\nwhich connects average swimming velocity and frequency-dependent viscosity of\nthe surrounding medium. In this relation, the viscous contribution can exist\nonly when the time-reversal symmetry is broken, whereas the elastic\ncontribution is present only when the structural symmetry of the swimmer is\nbroken. The Purcell's scallop theorem breaks down for a three-sphere swimmer in\na viscoelastic medium."
    },
    {
        "anchor": "A Molecular Theory of the Nematic-Nematic Phase Transitions in Mesogenic\n  Dimers: We present a simplified molecular model of mesogenic dimers consisting of two\nidentical uniaxial mesogenic cores separated by a fixed-length spacer and\nallowed to assume only two, statistically equivalent, conformations which are\nnon-planar and of opposite handedness. In the mean-field approximation, with\nadditive interactions among the mesogenic cores, the model yields up to three\npositionally disordered phases, one isotropic and two nematic. The low\ntemperature nematic phase ($\\mathrm{N_X}$) has a local two-fold symmetry axis\nwhich is also a direction of molecular polar ordering and is tightly twisted\nabout a macroscopic phase axis. The onset of polar ordering generates\nspontaneous chiral symmetry breaking, manifested primarily by the twisting of\nthe polar director and the formation of chiral domains of opposite handedness.\nWithin these domains the statistical balance between the two enantiomer\nconformations is shifted and the principal axes of the ordering tensors of the\nmolecular segments twist at constant tilt angles with the helix axis. Key\nexperimental results on the $\\mathrm{N_X}$ phase of liquid crystalline dimers\nare discussed in the light of the theoretical predictions of the model, which\nare also contrasted with the predictions of the twist-bend nematic model.",
        "positive": "Symmetric three-particle motion in Stokes flow: equilibrium for heavy\n  spheres in contrast to \"end-of-world\" for point forces: A stationary stable solution of the Stokes equations for three identical\nheavy solid spheres falling in a vertical plane is found. It has no analog in\nthe point-particle approximation. Three spheres aligned horizontally at equal\ndistances evolve towards the equilibrium relative configuration while the point\nparticles collapse onto a single point in a finite time."
    },
    {
        "anchor": "Controllable Capillary Assembly of Magnetic Ellipsoidal Janus Particles\n  into Tunable Rings, Chains and Hexagonal Lattices: Colloidal assembly at fluid interfaces has a great potential for the\nbottom-up fabrication of novel structured materials. However, challenges remain\nin realizing controllable and tunable assembly of particles into diverse\nstructures. Herein, we report the capillary assembly of magnetic ellipsoidal\nJanus particles at a fluid-fluid interface. Depending on their tilt angle, i.e.\nthe angle the particle main axis forms with the fluid interface, these\nparticles deform the interface and generate capillary dipoles or hexapoles.\nDriven by capillary interactions, multiple particles thus assemble into chain-,\nhexagonal lattice- and ring-like structures, which can be actively controlled\nby applying an external magnetic field. We predict a field-strength phase\ndiagram in which various structures are present as stable states. Owing to the\ndiversity, controllability, and tunability of assembled structures, magnetic\nellipsoidal Janus particles at fluid interfaces could therefore serve as\nversatile building blocks for novel materials.",
        "positive": "Frozen states and order-disorder transition in the dynamics of confined\n  membranes: The adhesion dynamics of a membrane confined between two permeable walls is\nstudied using a two-dimensional hydrodynamic model. The membrane morphology\ndecomposes into adhesion patches on the upper and the lower walls and obeys a\nnonlinear evolution equation that resembles that of phase separation dynamics,\nwhich is known to lead to coarsening, i.e. to the endless growth of the\nadhesion patches. However, due to the membrane bending rigidity the system\nevolves towards a frozen state without coarsening. This frozen state exhibits\nan order-disorder transition when increasing the permeability of the walls."
    },
    {
        "anchor": "Coarse-grained theory for motion of solitons and skyrmions in liquid\n  crystals: Recent experiments have found that applied electric fields can induce motion\nof skyrmions in chiral nematic liquid crystals. To understand the magnitude and\ndirection of the induced motion, we develop a coarse-grained approach to\ndescribe dynamics of skyrmions, similar to our group's previous work on the\ndynamics of disclinations. In this approach, we represent a localized\nexcitation in terms of a few macroscopic degrees of freedom, including the\nposition of the excitation and the orientation of the background director. We\nthen derive the Rayleigh dissipation function, and hence the equations of\nmotion, in terms of these macroscopic variables. We demonstrate this\ntheoretical approach for 1D motion of a sine-Gordon soliton, and then extend it\nto 2D motion of a skyrmion. Our results show that skyrmions move in a direction\nperpendicular to the induced tilt of the background director. When the applied\nfield is removed, skyrmions move in the opposite direction but not with equal\nmagnitude, and hence the overall motion may be rectified.",
        "positive": "Concentration Dependence of Elastic and Viscoelastic Properties of\n  Aqueous Solutions of Ficoll and Bovine Serum Albumin by Brillouin Light\n  Scattering Spectroscopy: The cellular environment is crowded with macromolecules of different shapes\nand sizes. The effect of this macromolecular crowding has been studied in a\nvariety of synthetic crowding environments: two popular examples are the\ncompact colloid-like Ficoll macromolecule, and the globular protein bovine\nserum albumin (BSA). Recent studies have indicated a significant component of\nbound or surface-associated water in these crowders reduces the available free\nvolume. In this work, Brillouin light scattering experiments were performed on\naqueous solutions of Ficoll 70 and Ficoll 400 with concentrations ranging from\n1 wt% to 35 wt% and BSA with concentrations of 1 wt% to 27 wt%. From the\ndependence of spectral peak parameters on polymer concentration, we determined\nfundamental solution properties: hypersound velocity, adiabatic bulk modulus\nand compressibility, apparent viscosity, and hypersound attenuation. Existing\ntheory that ignores intermolecular interactions can only capture the observed\nlinear trends in the frequency shift up to a threshold concentration, beyond\nwhich a quadratic term accounting for intermolecular interactions is necessary.\nThis likely indicates a transition from the dilute to semi-dilute regime. In\nthe Ficoll solutions (but not BSA) we see evidence for a central mode, with a\ncharacteristic relaxation time of 20 ps, that we attribute to exchange of the\nbound water."
    },
    {
        "anchor": "Influence of the fluid structure on the binding potential: comparing\n  liquid drop profiles from density functional theory with results from\n  mesoscopic theory: For a film of liquid on a solid surface, the binding potential $g(h)$ gives\nthe free energy as a function of the film thickness $h$ and also the closely\nrelated structural disjoining pressure $\\Pi = - \\partial g / \\partial h$. The\nwetting behaviour of the liquid is encoded in the binding potential and the\nequilibrium film thickness corresponds to the value at the minimum of $g(h)$.\nHere, the method we developed in [J. Chem. Phys. 142, 074702 (2015)], and\napplied with a simple discrete lattice-gas model, is used with continuum\ndensity functional theory (DFT) to calculate the binding potential for a\nLennard-Jones fluid and other simple liquids. The DFT used is based on\nfundamental measure theory and so incorporates the influence of the layered\npacking of molecules at the surface and the corresponding oscillatory density\nprofile. The binding potential is frequently input in mesoscale models from\nwhich liquid drop shapes and even dynamics can be calculated. Here we show that\nthe equilibrium droplet profiles calculated using the mesoscale theory are in\ngood agreement with the profiles calculated directly from the microscopic DFT.\nFor liquids composed of particles where the range of the attraction is much\nless than the diameter of the particles, we find that at low temperatures\n$g(h)$ decays in an oscillatory fashion with increasing $h$, leading to highly\nstructured terraced liquid droplets.",
        "positive": "Colloidal aggregates tested via nanoindentation and simultaneous 3D\n  imaging: The mechanical properties of aggregated colloids depend on the mutual\ninterplay of inter-particle potentials, contact forces, aggregate structure and\nmaterial properties of the bare particles. Owing to this variety of influences\nexperimental results from macroscopic mechanical testings were mostly compared\nto time-consuming, microscopic simulations rather than to analytical theories.\nThe aim of the present paper was to relate both macroscopic and microscopic\nmechanical data with each other and simple analytical models. We investigated\ndense amorphous aggregates made from monodisperse poly-methyl methacrylate\n(PMMA) particles (diameter: 1.6\\mu m) via nanoindentation in combination with\nconfocal microscopy. The resulting macroscopic information were complemented by\nthe three dimensional aggregate structure as well as the microscopic strain\nfield. The strain field was in reasonable agreement with the predictions from\nanalytical continuum theories. As a consequence the measured force-depth curves\ncould be analyzed within a theoretical framework that has frequently been used\nfor nanoindentation of atomic matter such as metals, ceramics and polymers. The\nextracted values for hardness and effective elastic modulus represented average\nvalues characteristic of the aggregate. On base of these parameters we discuss\nthe influence of the strength of particle bonds by introducing polystyrene (PS)\nbetween the particles."
    },
    {
        "anchor": "Dynamical States in Driven Colloidal Liquid Crystals: We study a model colloidal liquid crystal consisting of hard spherocylinders\nunder the influence of an external aligning potential by Langevin dynamics\nsimulation. The external field that rotates in a plane acts on the orientation\nof the individual particles and induces a variety of collective nonequilibrium\nstates. We characterize these states by the time-resolved orientational\ndistribution of the particles and explain their origin using the single\nparticle behavior. By varying the external driving frequency and the packing\nfraction of the spherocylinders we construct the dynamical state diagram.",
        "positive": "Patchy landscapes promote stability of small groups: Group formation and coordination are fundamental characteristics of living\nsystems, essential for performing tasks and ensuring survival. Interactions\nbetween individuals play a key role in group formation, and the impact of\nresource distributions is a vibrant area of research. Using active particles in\na tuneable optical environment as a model system, we demonstrate that\nheterogeneous energy source distributions result in smaller, more stable groups\nwith reduced individual exchange between clusters compared to homogeneous\nconditions. Reduced group sizes can be beneficial to optimise resources in\nheterogeneous environments and to control information flow within populations.\nDevoid of biological complications, our system provides insights into the\nimportance of patchy landscapes in ecological dynamics and holds implications\nfor refining swarm intelligence algorithms and enhancing crowd control\ntechniques."
    },
    {
        "anchor": "Comparison of time reversal symmetric and asymmetric nano-swimmers\n  oriented with an electric field in soft matter: Using molecular dynamics simulations we compare the motion of a nano-swimmer\nbased on Purcell suggested motor with a time asymmetrical cycle with the motion\nof the same molecular motor with a time symmetrical cycle. We show that Purcell\ntheorem still holds at the nanoscale, despite the local structure and the\nmedium fluctuations. Then, with the purpose of both orienting the swimmer\ndisplacement and increasing the breakdown of the theorem, we study the effect\nof an electric field on a polarized version of these swimmers. For small and\nlarge fields, the time asymmetrical swimmer is more efficient, as suggested by\nPurcell. However we find a field range for which Purcell theorem is broken for\nthe time symmetric motor. Results suggest that the breakdown of the theorem is\narising from the competition of the orientation field and Brownian forces,\nwhile for larger fields the field destroys the effect of fluctuations restoring\nthe theorem.",
        "positive": "Hydrodynamic stress correlations in fluid films driven by stochastic\n  surface forcing: We study hydrodynamic fluctuations in a compressible and viscous fluid film\nconfined between two rigid, no-slip, parallel plates, where one of the plates\nis kept fixed, while the other one is driven in small-amplitude, translational,\ndisplacements around its reference position. This jiggling motion is assumed to\nbe driven by a stochastic, external, surface forcing of zero mean and finite\nvariance. Thus, while the transverse (shear) and longitudinal (compressional)\nhydrodynamic stresses produced in the film vanish on average on either of the\nplates, these stresses exhibit fluctuations that can be quantified through\ntheir equal-time, two-point, correlation functions. For transverse stresses, we\nshow that the correlation functions of the stresses acting on the same plate\n(self-correlators) as well as the correlation function of the stresses acting\non different plates (cross-correlators) exhibit universal, decaying, power-law\nbehaviors as functions of the inter-plate separation. At small separations, the\nexponents are given by -1, while at large separations, the exponents are found\nas -2 (self-correlator on the fixed plate), -4 (excess self-correlator on the\nmobile plate) and -3 (cross-correlator). For longitudinal stresses, we find\nmuch weaker power-law decays in the large separation regime, with exponents\n-3/2 (excess self-correlator on the mobile plate) and -1 (cross-correlator).\nThe self-correlator on the fixed plate increases and levels off upon increasing\nthe inter-plate separation, reflecting the non-decaying nature of the\nlongitudinal forces acting on the fixed plate."
    },
    {
        "anchor": "Polymer effects on Karman Vortex: Molecular Dynamics Study: We investigated the Karman vortex behind a circular cylinder in a polymer\nsolution by a molecular dynamics simulation. The vortex characteristics are\ndistinctly different for short and long polymers. The solution with the long\npolymer exhibits a reduction in the vortex shedding frequency and broadening of\nthe lift coefficient spectrum. On the other hand, the characteristics of the\nshort-polymer solution are almost same as those of the Newtonian fluid. These\nfacts are consistent with the experiments. Because the distributions of the\ngyration radius and the orientational order of the long-polymer solution are\nhighly inhomogeneous in the flow field, we conclude that the extensional\nproperty of the polymer plays an important role in changing the flow\ncharacteristics.",
        "positive": "Mobility in immersed granular materials upon cyclic loading: We study the mobility of objects embedded in an immersed granular packing and\nsubjected to cyclic loadings. In this aim, we conducted experiments using glass\nbeads immersed in water and a horizontal plate subjected to a cyclic uplift\nforce. Tests performed at different cyclic force frequencies and amplitudes\nevidence the development of three mobility regimes whereby the plate stays\nvirtually immobile, moves up steadily or slowly creeps upwards. Results show\nthat steady plate uplift can occur at lower force magnitudes when the frequency\nis increased. We propose an interpretation of this frequency-weakening\nbehaviour based on force relaxation experiments and on the analysis of the\nmobility response of theoretical visco-elasto-plastic mechanical analogue.\nThese results and analysis point out inherent differences in mobility response\nbetween steady and cyclic loadings in immersed granular materials."
    },
    {
        "anchor": "On molecular and continuum boundary conditions for a miscible binary\n  fluid: We show that molecular dynamics simulations can furnish useful boundary\nconditions at a solid surface bounding a two-component fluid. In contrast to\nsome previous reports, convective-diffusive flow is consistent with continuum\nequations down to atomic scales. However, concentration gradients can produce\nflow without viscous dissipation that is inconsistent with the commonly used\nNavier slip condition. Also, differential wetting of the two components coupled\nto a concentration gradient can drive convective flows that could be used to\nmake nano-pumps or motors.",
        "positive": "Electric surface potential of dodecane nano-drops in aqueous solutions\n  of low ioinic strength: While the surface charge of solid particles is a direct consequence of their\nsynthesis, the one of suspended oil drops depends on the adsorption equilibrium\nof the surrounding molecules. The presence of salt raises the polarity of the\nwater phase, favoring the salting out of the surfactant from the aqueous\nsolution and increasing its surface excess. Yet, the electrolyte also screens\nthe resulting surface charge of the drops [Debye-H\\\"uckel, 1923]. As a result,\nthe electrostatic surface potential increases with the ionic strength until the\nsaturation of the interface and then decreases. This behavior produces a\nmaximum previously observed in hexadecane-in-water nanoemulsions\n[Urbina-Villalba, 2013; 2015]. Here, the variation of the surface potential of\ntwo dodecane-in-water (d/w) nanoemulsions is evaluated as a function of the\nsodium chloride concentration. As expected, maximum values are obtained for\nconcentrations of 0.5 and 7.5 mM sodium dodecylsulfate (SDS). However, the\nsurface excess of dodecane drops shows an intermediate behavior between the\nadsorption equilibrium predicted by macroscopic adsorption isotherms, and the\none previously found on hexadecane drops. The stability of the prepared\nemulsions was followed monitoring the change in the average radius of the\ndispersions during five minutes, six times the lapse of time employed in a\ntypical evaluation of the aggregation rate. In the case of 7.5 mM SDS, the\nsmallest change in size coincides with the maximum surface potential found (40\nmM NaCl). This is not observed for 0.5 mM SDS. Three regimes of destabilization\nare found to exist depending on the ionic strength of the aqueous phase. They\ncorrespond to the prevalence of: 1) solubilization/ripening, 2) aggregation,\nand 3) crystal precipitation."
    },
    {
        "anchor": "The influence of random pinning on the melting scenario of\n  two-dimensional soft-disk systems: We present the results of a computer simulation study of the melting scenario\nof two-dimensional soft-disk systems with potential\n$U(r)=\\varepsilon(\\sigma/r)^n$, $n=12$ and $n=1024$, both in the presence of\nrandom pinning and without it. The melting parameters have been determined from\nanalysis of the behavior of equations of state, correlation functions of the\norientational and translational order parameters, Young modulus and\nrenormalization group equations. The transition points obtained from these\ncriteria are in good agreement. We have shown that the systems melted in two\nstages - first-order hexatic phase to liquid transition and the continuous\nBerezinskii-Kosterlitz-Thouless type crystal-hexatic phase transition. Random\npinning widened the hexatic phase, but left the melting scenario unchanged.",
        "positive": "Interface Width and Bulk Stability: requirements for the simulation of\n  Deeply Quenched Liquid-Gas Systems: Simulations of liquid-gas systems with extended interfaces are observed to\nfail to give accurate results for two reasons: the interface can get ``stuck''\non the lattice or a density overshoot develops around the interface. In the\nfirst case the bulk densities can take a range of values, dependent on the\ninitial conditions. In the second case inaccurate bulk densities are found. In\nthis communication we derive the minimum interface width required for the\naccurate simulation of liquid gas systems with a diffuse interface. We\ndemonstrate this criterion for lattice Boltzmann simulations of a van der Waals\ngas. When combining this criterion with predictions for the bulk stability we\ncan predict the parameter range that leads to stable and accurate simulation\nresults. This allows us to identify parameter ranges leading to high density\nratios of over 1000. This is despite the fact that lattice Boltzmann\nsimulations of liquid-gas systems were believed to be restricted to modest\ndensity ratios of less than 20."
    },
    {
        "anchor": "Hydrodynamics of granular gases of inelastic and rough hard disks or\n  spheres. I. Transport coefficients: The transport coefficients for dilute granular gases of inelastic and rough\nhard disks or spheres with constant coefficients of normal ($\\alpha$) and\ntangential ($\\beta$) restitution are obtained in a unified framework as\nfunctions of the number of translational ($d_t$) and rotational ($d_r$) degrees\nof freedom. The derivation is carried out by means of the Chapman--Enskog\nmethod with a Sonine-like approximation in which, in contrast to previous\napproaches, the reference distribution function for angular velocities does not\nneed to be specified. The well-known case of purely smooth $d$-dimensional\nparticles is recovered by setting $d_t=d$ and formally taking the limit $d_r\\to\n0$. In addition, previous results [G. M. Kremer, A. Santos, and V. Garz\\'o,\nPhys. Rev. E 90, 022205 (2014)] for hard spheres are reobtained by taking\n$d_t=d_r=3$, while novel results for hard-disk gases are derived with the\nchoice $d_t=2$, $d_r=1$. The singular quasismooth limit ($\\beta\\to -1$) and the\nconservative Pidduck's gas ($\\alpha=\\beta=1$) are also obtained and discussed.",
        "positive": "Step-Bunching Transitions on Vicinal Surfaces and Quantum n-mers: We study vicinal crystal surfaces within the terrace-step-kink model on a\ndiscrete lattice. Including both a short-ranged attractive interaction and a\nlong-ranged repulsive interaction arising from elastic forces, we discover a\nseries of phases in which steps coalesce into bunches of $n_b$ steps each. The\nvalue of $n_b$ varies with temperature and the ratio of short to long range\ninteraction strengths. For bunches with large number of steps, we show that, at\nT=0, our bunch phases correspond to the well known periodic groove structure\nfirst predicted by Marchenko. An extension to $T>0$ is developed. We propose\nthat the bunch phases have been observed in very recent experiments on Si\nsurfaces, and further experiments are suggested. Within the context of a\nmapping of the model to a system of bosons on a 1D lattice, the bunch phases\nappear as quantum n-mers."
    },
    {
        "anchor": "Structural and dynamic properties of SPC/E water: I have investigated the structural and dynamic properties of water by\nperforming a series of molecular dynamic simulations in the range of\ntemperatures from 213 K to 360 K, using the Simple Point Charge-Extended\n(SPC/E) model. I performed isobaric-isothermal simulations (1 bar) of 1185\nwater molecules using the GROMACS package. I quantified the structural\nproperties using the oxygen-oxygen radial distribution functions, order\nparameters, and the hydrogen bond distribution functions, whereas, to analyze\nthe dynamic properties I studied the behavior of the history-dependent bond\ncorrelation functions and the non-Gaussian parameter alpha_2(t) of the mean\nsquare displacement of water molecules. When the temperature decreases, the\ntranslational (tau) and orientational (Q) order parameters are linearly\ncorrelated, and both increase indicating an increasing structural order in the\nsystems. The probability of occurrence of four hydrogen bonds and Q both have a\nreciprocal dependence with T, though the analysis of the hydrogen bond\ndistributions permits to describe the changes in the dynamics and structure of\nwater more reliably. Thus, an increase on the caging effect and the occurrence\nof long-time hydrogen bonds occur below 293 K, in the range of temperatures in\nwhich predominates a four hydrogen bond structure in the system.",
        "positive": "Anomalous Scaling and Solitary Waves in Systems with Non-Linear\n  Diffusion: We study a non-linear convective-diffusive equation, local in space and time,\nwhich has its background in the dynamics of the thickness of a wetting film.\nThe presence of a non-linear diffusion predicts the existence of fronts as well\nas shock fronts. Despite the absence of memory effects, solutions in the case\nof pure non-linear diffusion exhibit an anomalous sub-diffusive scaling. Due to\na balance between non-linear diffusion and convection we, in particular, show\nthat solitary waves appear. For large times they merge into a single solitary\nwave exhibiting a topological stability. Even though our results concern a\nspecific equation, numerical simulations supports the view that anomalous\ndiffusion and the solitary waves disclosed will be general features in such\nnon-linear convective-diffusive dynamics."
    },
    {
        "anchor": "Pair correlation functions and phase separation in a two component point\n  Yukawa fluid: We investigate the structure of a binary mixture of particles interacting via\npurely repulsive (point) Yukawa pair potentials with a common inverse screening\nlength $\\lambda$. Using the hyper-netted chain closure to the Ornstein-Zernike\nequations, we find that for a system with `ideal' (Berthelot mixing rule) pair\npotential parameters for the interaction between unlike species, the asymptotic\ndecay of the total correlation functions crosses over from monotonic to damped\noscillatory on increasing the fluid total density at fixed composition. This\ngives rise to a Kirkwood line in the phase diagram. We also consider a\n`non-ideal' system, in which the Berthelot mixing rule is multiplied by a\nfactor $(1+\\delta)$. For any $\\delta>0$ the system exhibits fluid-fluid phase\nseparation and remarkably the ultimate decay of the correlation functions is\nnow monotonic for all (mixture) state points. Only in the limit of vanishing\nconcentration of either species does one find oscillatory decay extending to $r\n= \\infty$. In the non-ideal case the simple random phase approximation provides\na good description of the phase separation and the accompanying Lifshitz line.",
        "positive": "Discrete elastic model for stretching-induced flagellar polymorphs: Force-induced reversible transformations between coiled and normal polymorphs\nof bacterial flagella have been observed in recent optical-tweezer experiment.\nWe introduce a discrete elastic rod model with two competing helical states\ngoverned by a fluctuating spin-like variable that represents the underlying\nconformational states of flagellin monomers. Using hybrid Brownian dynamics\nMonte-Carlo simulations, we show that a helix undergoes shape transitions\ndominated by domain wall nucleation and motion in response to externally\napplied uniaxial tension. A scaling argument for the critical force is\npresented in good agreement with experimental and simulation results.\nStretching rate-dependent elasticity including a buckling instability are\nfound, also consistent with the experiment."
    },
    {
        "anchor": "Cluster Crystals in Confinement: This paper has been withdrawn by the author(s), due to technical copyright\nproblems with the Royal Society of Chemistry.",
        "positive": "Superfluid-Mott Insulator Transition of Spin-1 Bosons in an Optical\n  Lattice: We have studied superfluid-Mott insulating transition of spin-1 bosons\ninteracting antiferromagnetically in an optical lattice. We have obtained the\nzero-temperature phase diagram by a mean-field approximation and have found\nthat the superfluid phase is to be a polar state as a usual trapped spin-1 Bose\ngas. More interestingly, we have found that the Mott-insulating phase is\nstrongly stabilized only when the number of atoms per site is even."
    },
    {
        "anchor": "Viscosity of protein-stabilised emulsions: contributions of components\n  and development of a semi-predictive model: Protein-stabilised emulsions can be seen as mixtures of unadsorbed proteins\nand of protein-stabilised droplets. To identify the contributions of these two\ncomponents to the overall viscosity of sodium caseinate o/w emulsions, the\nrheological behaviour of pure suspensions of proteins and droplets were\ncharacterised, and their properties used to model the behaviour of their\nmixtures. These materials are conveniently studied in the framework developed\nfor soft colloids. Here, the use of viscosity models for the two types of pure\nsuspensions facilitates the development of a semi-empirical model that relates\nthe viscosity of protein-stabilised emulsions to their composition.",
        "positive": "On the influence of a patterned substrate on crystallization in\n  suspensions of hard spheres: We present a computer simulation study on crystal nucleation and growth in\nsupersaturated suspensions of mono-disperse hard spheres induced by a\ntriangular lattice substrate. The main result is that compressed substrates are\nwet by the crystalline phase (the crystalline phase directly appears without\nany induction time), while for stretched substrates we observe heterogeneous\nnucleation. The shapes of the nucleated crystallites fluctuate strongly. In the\ncase of homogeneous nucleation amorphous precursors have been observed (Phys.\nRev. Lett. {\\bf 105}(2):025701 (2010)). For heterogeneous nucleation we do not\nfind such precursors. The fluid is directly transformed into highly ordered\ncrystallites."
    },
    {
        "anchor": "Diblock copolymer ordering induced by patterned surfaces: We use a Ginzburg-Landau free energy functional to investigate diblock\ncopolymer morphologies when the copolymer melt interacts with one surface or is\nconfined between two chemically patterned surfaces. For temperatures above the\norder-disorder transition a complete linear response description of the\ncopolymer melt is given, in terms of an arbitrary two-dimensional surface\npattern. The appearance of order in the direction parallel to the surface is\nfound as a result of the order in the perpendicular direction. Below the\norder-disorder point and in a thin-film geometry, our procedure enables the\nanalytic calculation of distorted perpendicular and tilted lamellar phases in\nthe presence of uniform or modulated surface fields.",
        "positive": "Surface relaxation of lyotropic lamellar phases: We study the relaxation modes of an interface between a lyotropic lamellar\nphase and a gas or a simple liquid. The response is found to be qualitatively\ndifferent from those of both simple liquids and single-component smectic-A\nliquid crystals. At low rates it is governed by a non-inertial, diffusive mode\nwhose decay rate increases quadratically with wavenumber, $|\\omega|=Aq^2$. The\ncoefficient $A$ depends on the restoring forces of surface tension,\ncompressibility and bending, while the dissipation is dominated by the\nso-called slip mechanism, i.e, relative motion of the two components of the\nphase parallel to the lamellae. This surface mode has a large penetration depth\nwhich, for sterically stabilised phases, is of order $(dq^2)^{-1}$, where $d$\nis the microscopic lamellar spacing."
    },
    {
        "anchor": "Overdamped Stress Relaxation in Buckled Rods: We present a comprehensive theoretical analysis of the stress relaxation in a\nmultiply but weakly buckled incompressible rod in a viscous solvent. In the\nbulk two interesting regimes of generic self--similar intermediate asymptotics\nare distinguished, which give rise to two classes of approximate and exact\npower--law solutions, respectively. For the case of open boundary conditions\nthe corresponding non--trivial boundary--layer scenarios are derived by a\nmultiple--scale perturbation (``adiabatic'') method. Our results compare well\nwith -- and provide the theoretical explanation for -- previous results from\nnumerical simulations, and they suggest new directions for further fruitful\nnumerical and experimental investigations.",
        "positive": "Theory of Polar Blue Phases: In liquid crystals, if flexoelectric couplings between polar order and\ndirector gradients are strong enough, the uniform nematic phase can become\nunstable to formation of a modulated polar phase. Previous theories have\npredicted two types of modulation, twist-bend and splay-bend; the twist-bend\nphase has been found in recent experiments. Here, we investigate other types of\nmodulation, using lattice simulations and Landau theory. In addition to\ntwist-bend and splay-bend, we also find polar blue phases, with 2D or 3D\nmodulations of both director and polar order. We compare polar blue phases with\nchiral blue phases, and discuss opportunities for observing them\nexperimentally."
    },
    {
        "anchor": "Analytical model of atomic-force-microscopy force curves in viscoelastic\n  materials exhibiting power law relaxation: We propose an analytical model for the force-indentation relationship in\nviscoelastic materials exhibiting a power law relaxation described by an\nexponent n, where n = 1 represents the standard viscoelastic solid (SLS) model,\nand n < 1 represents a fractional SLS model. To validate the model, we perform\nnanoindentation measurements of poylacrylamide gels with atomic force\nmicroscopy (AFM) force curves. We found exponents n < 1 that depends on the\nbysacrylamide concentration. We also demonstrate that the fitting of AFM force\ncurves for varying load speeds can reproduce the dynamic viscoelastic\nproperties of those gels measured with dynamic force modulation methods.",
        "positive": "Generalized Director Approach for Liquid-Crystal-Based Reconfigurable RF\n  Devices: This letter presents a closed-form integral-equation formulation that models\nthe director tilting in nematic liquid crystals. The proposed formulation is\ncomputationally efficient compared to numerical methods and provides a physical\ninsight on the matter. Our previous work is generalized from the one-constant\napproach to all the possible cases that cover the elastic constants. These\nconstants determine in great extent the electrical properties of the liquid\ncrystal, and subsequently, the response of the reconfigurable devices that take\nuse of it. Therefore, a more precise but still simple modeling of their\ninfluence is pursued here. Simulations show good agreement with numerical\nimplementations. In comparison, the error in the estimation is considerably\nreduced when using the integral-equation formulation, specially as the\npolarization voltage or the dielectric anisotropy decreases."
    },
    {
        "anchor": "Toughening and asymmetry in peeling of heterogeneous adhesives: The effective adhesive properties of heterogeneous thin films are\ncharacterized through a combined experimental and theoretical investigation. By\nbridging scales, we show how variations of elastic or adhesive properties at\nthe microscale can significantly affect the effective peeling behavior of the\nadhesive at the macroscale. Our study reveals three elementary mechanisms in\nheterogeneous systems involving front propagation: (i) patterning the elastic\nbending stiffness of the film produces fluctuations of the driving force\nresulting in dramatically enhanced resistance to peeling; (ii) optimized\narrangements of pinning sites with large adhesion energy are shown to control\nthe effective system resistance, allowing the design of highly anisotropic and\nasymmetric adhesives; (iii) heterogeneities of both types result in front\nmotion instabilities producing sudden energy releases that increase the overall\nadhesion energy. These findings open potentially new avenues for the design of\nthin films with improved adhesion properties, and motivate new investigation of\nother phenomena involving front propagation.",
        "positive": "Optimal load sharing in bioinspired fibrillar adhesives: Asymptotic\n  solution: We propose here an asymptotic solution defining the optimal compliance\ndistribution for a fibrillar adhesive to obtain maximum theoretical strength.\nThis condition corresponds to that of equal load sharing (ELS) among fibrils,\ni.e. all the fibrils are carrying the same load at detachment, hence they all\ndetach simultaneously. We model the array of fibrils as a continuum of linear\nelastic material that cannot laterally transmit load (analogous to a Winkler\nsoil). Ultimately, we obtain the continuum distribution of fibril's compliance\nin closed-form solution and compare it with previously obtained data for a\ndiscrete model for fibrillar adhesives. The results show improving accuracy for\nan incremental number of fibrils and smaller center-to-center spacing.\nSurprisingly, the approximation introduced by the asymptotic model show reduced\nsensitivity of the adhesive strength with respect to misalignment and improved\nadhesive strength for large misalignment angles."
    },
    {
        "anchor": "Second harmonic light scattering induced by defects in the twist-bend\n  nematic phase of liquid crystal dimers: The nematic twist-bend ($\\mathrm{N_{TB}}$) phase, exhibited by certain\nthermotropic liquid crystalline (LC) dimers, represents a new orientationally\nordered mesophase -- the first distinct nematic variant discovered in many\nyears. The $\\mathrm{N_{TB}}$ phase is distinguished by a heliconical winding of\nthe average molecular long axis (director) with a remarkably short (nanoscale)\npitch and, in systems of achiral dimers, with an equal probability to form\nright- and left-handed domains. The $\\mathrm{N_{TB}}$ structure thus provides\nanother fascinating example of spontaneous chiral symmetry breaking in nature.\nThe order parameter driving the formation of the heliconical state has been\ntheoretically conjectured to be a polarization field, deriving from the bent\nconformation of the dimers, that rotates helically with the same nanoscale\npitch as the director field. It therefore presents a significant challenge for\nexperimental detection. Here we report a second harmonic light scattering\n(SHLS) study on two achiral, $\\mathrm{N_{TB}}$-forming LCs, which is sensitive\nto the polarization field due to micron-scale distortion of the helical\nstructure associated with naturally-occurring textural defects. These defects\nare parabolic focal conics of smectic-like \"pseudo-layers\", defined by planes\nof equivalent phase in a coarse-grained description of the $\\mathrm{N_{TB}}$\nstate. Our SHLS data are explained by a coarse-grained free energy density that\ncombines a Landau-deGennes expansion of the polarization field, the elastic\nenergy of a nematic, and a linear coupling between the two.",
        "positive": "Theory of the splay nematic phase: Single vs. double splay: Recent experiments have reported a novel splay nematic phase, which has\nalternating domains of positive and negative splay. To model this phase,\nprevious studies have considered a 1D splay modulation of the director field,\naccompanied by a 1D modulation of polar order. When the flexoelectric coupling\nbetween splay and polar order becomes sufficiently strong, the uniform nematic\nstate becomes unstable to the formation of a modulated phase. Here, we\nre-examine this theory in terms of a new approach to liquid crystal elasticity,\nwhich shows that pure splay deformation is double splay rather than planar\nsingle splay. Following that reasoning, we propose a structure with a 2D splay\nmodulation of the director field, accompanied by a 2D modulation of polar\norder, and show that the 2D structure generally has a lower free energy than\nthe 1D structure."
    },
    {
        "anchor": "Effect of orientational restriction on monolayers of hard ellipsoids: The effect of out-of-plane orientational freedom on the orientational\nordering properties of a monolayer of hard ellipsoids is studied using\nParsons-Lee scaling approach and replica exchange Monte Carlo computer\nsimulation. Prolate and oblate ellipsoids exhibit very different ordering\nproperties, namely, the axes of revolution of prolate particles tend to lean\nout, while those of oblate ones prefer to lean into the confining plane. The\ndriving mechanism of this is that the particles try to maximize the available\nfree area on the confining surface, which can be achieved by minimizing the\ncross section areas of the particles with the plane. In the lack out-of-plane\norientational freedom the monolayer of prolate particles is identical to a\ntwo-dimensional hard ellipse system, which undergoes an isotropic-nematic\nordering transition with increasing density. With gradually switching on the\nout-of-plane orientational freedom the prolate particles lean out from the\nconfining plane and a destabilisation of the in-plane isotropic-nematic phase\ntransition is observed. The system of oblate particles behaves oppositely to\nthat of prolates. It corresponds to a two-dimensional system of hard disks in\nthe lack of out-of-plane freedom, while it behaves similar to that of hard\nellipses in the freely rotating case.",
        "positive": "\u00c5ngstr\u00f6m-scale chemically powered motors: Like their larger micron-scale counterparts, {\\AA}ngstr\\\"om-scale chemically\nself-propelled motors use asymmetric catalytic activity to produce\nself-generated concentration gradients that lead to directed motion. Unlike\ntheir micron-scale counterparts, the sizes of {\\AA}ngstr\\\"om-scale motors are\ncomparable to the solvent molecules in which they move, they are dominated by\nfluctuations, and they operate on very different time scales. These new\nfeatures are studied using molecular dynamics simulations of small sphere dimer\nmotors. We show that the ballistic regime is dominated by the thermal speed but\nthe diffusion coefficients of these motors are orders of magnitude larger than\ninactive dimers. Such small motors may find applications in nano-confined\nsystems or perhaps eventually in the cell."
    },
    {
        "anchor": "Peristaltic pumps work in nano scales: A design for a pump is suggested which is based on well-known peristaltic\npumps. In order to simply describe the operation of the proposed pump, an\ninnovative interpretation of low Reynolds number swimmers is presented and\nthereafter a similar theoretical model would be suggested to quantify the\nbehavior of the pumps. A coarse-grained molecular dynamic simulation is used to\nexamine the theoretical predictions and measure the efficiency of the pump in\nnano scales. It is shown that this pump with a modest design is capable of\nbeing a good option for transport processes in nano scale.",
        "positive": "Non-linear physical aging of supercooled glycerol induced by large\n  upward ideal temperature steps monitored through cooling experiments: The physical aging of supercooled glycerol induced by upward temperature\nsteps of amplitude reaching 45 K was studied by a new method consisting in\nheating a micrometer-thick liquid film at a rate of up to 60 000 K/s, holding\nit at a constant high temperature for a controlled duration before letting it\nquickly cool down to the initial temperature. By monitoring the final slow\nrelaxation of the dielectric loss, we were able to obtain quantitative\ninformation on the liquid response to the initial upward step. The so-called\nTNM (Tool-Narayanaswamy-Moynihan) formalism provided a good description of our\nobservations despite the large distance from equilibrium, provided that\ndifferent values of the nonlinearity parameter were used for the cooling phase\nand for the (much further from equilibrium) heating phase. In this form, it\nallowed to precisely quantify how to design an ideal temperature step, i.e.,\nwhere no relaxation occurs during the heating phase. It helped bringing a clear\nphysical understanding of how the (kilosecond long) final relaxation is related\nto the (millisecond long) liquid response to the upward step. Finally, it made\npossible the reconstruction of the fictive temperature evolution immediately\nfollowing a step, evidencing the highly non-linear character of the liquid\nresponse to such large amplitude temperature steps. This work illustrates both\nthe strengths and limitations of the TNM approach. This new experimental device\noffers a promising tool to study far-from-equilibrium supercooled liquids\nthrough their dielectric response."
    },
    {
        "anchor": "Kelvin force in a layer of magnetic fluid: The Kelvin force in a layer of magnetic fluid subjected to a homogeneous\nmagnetic field and local heating is studied. The study is motivated by the\nquestion about the corresponding Kelvin force density [M. Liu, Phys. Rev.\nLett., 2762 (2000)]. It is shown that the usual and the newly proposed\nformulation of the Kelvin force are entirely equivalent. It is only when\napproximations are introduced that differences arise.",
        "positive": "Nucleation of a non-critical phase in a fluid near a critical point: Phase diagrams of some globular proteins have a fluid-fluid transition as\nwell as a fluid-crystal transition. Homogeneous nucleation of the crystal from\nthe fluid phase near the critical point of the fluid-fluid transition is\nexamined. As the fluid-fluid critical point is approached, the number of\nmolecules in the critical nucleus, the nucleus at the top of the free energy\nbarrier to nucleation, is found to diverge as the isothermal compressibility.\nThis divergence is due to a layer of the fluid phase of width equal to the\nfluid's correlation length which surrounds the core of the nucleus; the number\nof molecules in a crystalline environment in the nucleus does not diverge. The\nfree energy barrier to nucleation remains finite but its derivative with\nrespect to the chemical potential is equal to minus the number of molecules in\nthe critical nucleus and so diverges."
    },
    {
        "anchor": "Saturated nucleate pool boiling of oxygen under magnetically-enhanced\n  effective gravity: We investigate the effect of enhancing gravity on saturated nucleate pool\nboiling of oxygen for effective gravities of 1g, 6.0g, and 16g (g=9.8 m/s^2) at\na saturation pressure of 760 torr and for heat fluxes of 10 ~ 3000 W/m^2. The\neffective gravity on the oxygen is increased by applying a magnetic body force\ngenerated by a superconducting solenoid. We measure the heater temperature\n(expressed as a reduced superheat) as a function of heat flux and fit this data\nto a piecewise power-law/linear boiling curve. At low heat flux (<400 W/m^2)\nthe superheat is proportional to the cube root of the heat flux. At higher heat\nfluxes, the superheat is a linear function of the heat flux. To within\nstatistical uncertainties, which are limited by variations among experimental\nruns, we find no variation of the boiling curve over our applied gravity range.",
        "positive": "Short and soft: multi-domain organization, tunable dynamics and jamming\n  in suspensions of grafted colloidal cylinders with small aspect ratio: The yet virtually unexplored class of soft colloidal rods with small aspect\nratio is investigated and shown to exhibit a very rich phase and dynamic\nbehavior, spanning from liquid to nearly melt state. Instead of nematic order,\nthese short and soft nanocylinders alter their organization with increasing\nconcentration from isotropic liquid with random orientation to one with\npreferred local orientation and eventually a multi-domain arrangement with\nlocal orientational order. The latter gives rise to a kinetically suppressed\nstate akin to structural glass with detectable terminal relaxation, which, on\nincreasing concentration reveals features of hexagonally packed order as in\nordered block copolymers. The respective dynamic response comprises four\nregimes, all above the overlapping concentration of 0.02 g/ml: I) from 0.03 to\n0.1 g/mol the system undergoes a liquid-to-solid like transition with a\nstructural relaxation time that grows by four orders of magnitude. II) from 0.1\nto 0.2 g/ml a dramatic slowing-down is observed and is accompanied by an\nevolution from isotropic to multi-domain structure. III) between 0.2 and 0.6\ng/mol the suspensions exhibit signatures of shell interpenetration and jamming,\nwith the colloidal plateau modulus depending linearly on concentration. IV) at\n0.74 g/ml in the densely jammed state, the viscoelastic signature of\nhexagonally packed cylinders from microphase-separated block copolymers is\ndetected. These properties set short and soft nanocylinders apart from long\ncolloidal rods (with large aspect ratio) and provide insights for fundamentally\nunderstanding the physics in this intermediate soft colloidal regime, as well\nas and for tailoring the flow properties of non-spherical soft colloids."
    },
    {
        "anchor": "Shape anisotropy and Voids: Numerical simulations on a 2-dimensional model system showed that voids are\ninduced primarily due to shape anisotropy in binary mixtures of interacting\ndisks. The results of such a simple model account for the key features seen in\na variety of flux experiments using liposomes and biological membranes.",
        "positive": "Folding time dependence of the motions of a molecular motor diluted\n  inside an amorphous medium: We investigate the dependence of the displacements of a molecular motor\nembedded inside a glassy material on its folding characteristic time. We\nobserve two different time regimes. For slow foldings (regime I) the diffusion\nevolves very slowly with the folding time, while for rapid foldings (regime II)\nthe diffusion increases strongly with the folding time suggesting two different\nphysical mechanisms. We find that in regime I the motor displacement during the\nfolding process is counteracted by a reverse displacement during the unfolding,\nwhile in regime II this counteraction is much weaker. We notice that regime I\nbehavior is reminiscent of the scallop theorem that holds for larger motors in\na continuous medium. We find that the difference in the efficiency of the motor\nmotion explains most of the observed difference between the two regimes. For\nfast foldings the motor trajectories differ significantly from the opposite\ntrajectories induced by the following unfolding process, resulting in a more\nefficient global motion than for slow foldings. This result agrees with the\nfluctuation theorems expectation for time reversal mechanisms. In agreement\nwith the fluctuation theorems we find that the motors are unexpectedly more\nefficient when they are generating more entropy, a result that can be used to\nincrease dramatically the motor motion."
    },
    {
        "anchor": "Thermodynamic modeling using Extended UNIQUAC and COSMO-RS-ES models:\n  Case study of the cesium nitrate - water system over a large range of\n  temperatures: A comparison of two thermodynamic models is presented using the water-cesium\nnitrate system as case study. Both models were able to model the thermodynamic\nproperties such as the osmotic coefficient, vapor pressure, mean activity\ncoefficient and solubility with good accuracy. We show that it is possible to\nreproduce the temperature dependency of the properties using a simple set of\nparameters in the case of Extended UNIQUAC. Furthermore, COSMO-RS-ES is a\ncompletely predictive model adjusted to data at 298.15 K, which is applied for\nthe first time to other temperatures.",
        "positive": "Design and Folding of Dimeric Proteins: In a similar way in which the folding of single--domain proteins provide an\nimportant test in the study of self--organization, the folding of homodimers\nconstitute a basic challenge in the quest for the mechanisms which are at the\nbasis of biological recognition. Dimerization is studied by following the\nevolution of two identical 20--letter amino acid chains within the framework of\na lattice model and using Monte Carlo simulations. It is found that when design\n(evolution pressure) selects few, strongly interacting (conserved) amino acids\nto control the process, a three--state folding scenario follows, where the\nmonomers first fold forming the halves of the eventual dimeric interface\nindependently of each other, and then dimerize (\"lock and key\" kind of\nassociation). On the other hand, if design distributes the control of the\nfolding process on a large number of (conserved) amino acids, a two--state\nfolding scenario ensues, where dimerization takes place at the beginning of the\nproces, resulting in an \"induced type\" of association. Making use of\nconservation patterns of families of analogous dimers, it is possible to\ncompare the model predictions with the behaviour of real proteins. It is found\nthat theory provides an overall account of the experimental findings."
    },
    {
        "anchor": "Mean field approach of dynamical pattern formation in underdamped active\n  matter with short-ranged alignment and distant anti-alignment interactions: Many active matter systems, especially on the microscopic scale, are well\napproximated as overdamped, meaning that any inertial momentum is immediately\ndissipated by the environment. On the other hand, especially for macroscopic\nactive systems but also for many mesoscopic systems the time scale of inertial\nmotion can become large enough to be relevant for the dynamics. This raises the\nquestion how collective dynamics and the resulting states in active matter are\ninfluenced by inertia. Therefore, we propose a coarsegrained continuum model\nfor underdamped active matter based on a mean field description for passive\nsystems. Furthermore, we apply the model to a system with interactions that\nsupport an alignment on short distances and an antialignment on longer length\nscales as known in the context of pattern formation due to orientational\ninteractions. Our numerical calculations of the underand overdamped dynamics\nboth predict a structured laning state. However, activity induced convective\nflows that are only present in the underdamped model destabilize this state\nwhen the anti-alignment is weakened, leading to a collective motion state which\ndoes not occur in the overdamped limit. A turbulent transition regime between\nthe two states can be characterized by strong density fluctuations and the\nabsence of global ordering.",
        "positive": "Softness suppresses fivefold symmetry and enhances crystallization of\n  binary Laves phases in nearly hard spheres: Colloidal crystals with a diamond and pyrochlore structure display wide\nphotonic band gaps at low refractive index contrasts. However, these\nlow-coordinated and open structures are notoriously difficult to self-assemble\nfrom colloids interacting with simple pair interactions. To circumvent these\nproblems, one can self-assemble both structures in a closely packed MgCu2 Laves\nphase from a binary mixture of colloidal spheres and then selectively remove\none of the sublattices. Although Laves phases have been proven to be stable in\na binary hard-sphere system, they have never been observed to spontaneously\ncrystallize in such a fluid mixture in simulations nor in experiments of\nmicron-sized hard spheres due to slow dynamics. Here we demonstrate, using\ncomputer simulations, that softness in the interparticle potential suppresses\nthe degree of fivefold symmetry in the binary fluid phase and enhances\ncrystallization of Laves phases in nearly hard spheres."
    },
    {
        "anchor": "Beyond icosahedral symmetry in packings of proteins in spherical shells: The formation of quasi-spherical cages from protein building blocks is a\nremarkable self-assembly process in many natural systems, where a small number\nof elementary building blocks are assembled to build a highly symmetric\nicosahedral cage. In turn, this has inspired synthetic biologists to design de\nnovo protein cages. We use simple models, on multiple scales, to investigate\nthe self-assembly of a spherical cage, focusing on the regularity of the\npacking of protein-like objects on the surface. Using building blocks, which\nare able to pack with icosahedral symmetry, we examine how stable these highly\nsymmetric structures are to perturbations that may arise from the interplay\nbetween flexibility of the interacting blocks and entropic effects. We find\nthat, in the presence of those perturbations, icosahedral packing is not the\nmost stable arrangement for a wide range of parameters; rather disordered\nstructures are found to be the most stable. Our results suggest that (i) many\ndesigned, or even natural, protein cages may not be regular in the presence of\nthose perturbations, and (ii) that optimizing those flexibilities can be a\npossible design strategy to obtain regular synthetic cages with full control\nover their surface properties.",
        "positive": "Two-temperature activity induces liquid-crystal phases inaccessible in\n  equilibrium: In equilibrium hard-rod fluids, and in effective hard-rod descriptions of\nanisotropic soft-particle systems, the transition from the isotropic (I) phase\nto the nematic phase (N) is observed above the rod aspect ratio L/D = 3.70 as\npredicted by Onsager. We examine the fate of this criterion in a molecular\ndynamics study of a system of soft repulsive spherocylinders rendered active by\ncoupling half the particles to a heat bath at a higher temperature than that\nimposed on the other half. We show that the system phase separates and\nself-organizes into various liquid-crystalline phases that are not observed in\nequilibrium for the respective aspect ratios. In particular, we find a nematic\nphase for L/D = 3 and a smectic phase for L/D = 2 above a critical activity."
    },
    {
        "anchor": "Tracer diffusion coefficients in a moderately dense granular suspension.\n  Stability analysis and thermal diffusion segregation: The diffusion transport coefficients of a binary granular suspension where\none of the components is present in tracer concentration are determined from\nthe (inelastic) Enskog kinetic equation. The effect of the interstitial gas on\nthe solid particles is accounted for in the kinetic equation through two\ndifferent terms: (i) a viscous drag force proportional to the particle velocity\nand (ii) stochastic Langevin-like term defined in terms of the background\ntemperature. The transport coefficients are obtained as the solutions of a set\nof coupled linear integral equations recently derived for binary granular\nsuspensions with arbitrary concentration [G\\'omez Gonz\\'alez \\emph{et al.},\nPhys. Rev. E \\textbf{101}, 012904 (2020)]. To achieve analytical expressions\nfor the diffusion coefficients, the above integral equations are approximately\nsolved by considering the so-called second Sonine approximation. The\ntheoretical results for the tracer diffusion coefficient $D_0$ (coefficient\nconnecting the mass flux with the gradient of density of tracer particles) are\ncompared with those obtained by numerically solving the Enskog equation by\nmeans of the direct simulation Monte Carlo method. Although the first-Sonine\napproximation to $D_0$ yields in general a good agreement with simulation\nresults, we show that the second-Sonine approximation leads to an improvement\nover the first-Sonine correction, especially when the tracer particles are much\nlighter than the granular gas. The expressions derived here for the diffusion\ncoefficients are also used for two different applications. First, the stability\nof the homogeneous steady state is discussed. Second, segregation induced by a\nthermal gradient is studied. As expected, the results show that the\ncorresponding phase diagrams for segregation clearly differ from those found in\nprevious works when the effect of gas phase on grains is neglected.",
        "positive": "Dynamic depletion in a Bose condensate via a sudden increase of the\n  scattering length: We examine the time-dependent quantum depletion of a trapped Bose condensate\narising from a rapid increase of the scattering length. Our solution indicates\nthat a significant buildup of incoherent atoms can occur within a\ncharacteristic time short compared with the harmonic trap period. We discuss\nhow the depletion density and the characteristic time depend on the physical\nparameters of the condensate."
    },
    {
        "anchor": "Dense granular flows: two-particle argument accounts for friction-like\n  constitutive law with threshold: A scalar constitutive law is obtained for dense granular flows, both in the\ninertial regime where the grain inertia dominates, and in the viscous regime.\nConsidering a pair of grains rather than a single grain, the classical\narguments yield a constitutive law that exhibits a flow threshold expressed as\na finite effective friction at flow onset. The value of the threshold is not\npredicted. The resulting law seems to be compatible with existing data,\nprovided the saturation at high velocity (collisional regime) is added\nempirically. The law is not exactly the same in both regimes, which seems to\nindicate that there is no \"universal\" law.",
        "positive": "Equilibria and Instabilities of a Slinky: Discrete Model: The Slinky is a well-known example of a highly flexible helical spring,\nexhibiting large, geometrically nonlinear deformations from minimal applied\nforces. By considering it as a system of coils that act to resist axial,\nshearing, and rotational deformations, we develop a discretized model to\npredict the equilibrium configurations of a Slinky via the minimization of its\npotential energy. Careful consideration of the contact between coils enables\nthis procedure to accurately describe the shape and stability of the Slinky\nunder different modes of deformation. In addition, we provide simple geometric\nand material relations that describe a scaling of the general behavior of\nflexible, helical springs."
    },
    {
        "anchor": "Explaining the specific heat of liquids based on instantaneous normal\n  modes: The successful prediction of the specific heat of solids is a milestone in\nthe kinetic theory of matter, due to Debye (1912). No such success, however,\nhas ever been obtained for the specific heat of liquids, which has remained a\nmystery for over a century. A theory of specific heat of liquids is derived\nhere using a recently proposed analytical form of the vibrational density of\nstates (DOS) of liquids, which takes into account saddle points in the liquid\nenergy landscape via the so-called instantaneous normal modes (INMs),\ncorresponding to negative eigenvalues (imaginary frequencies) of the Hessian\nmatrix. The theory is able to explain the typical monotonic decrease of\nspecific heat with temperature observed in liquids, in terms of the average INM\nexcitation lifetime decreasing with T (in accordance with Arrehnius law), and\nprovides an excellent single-parameter fitting to several sets of experimental\ndata for atomic and molecular liquids. It also correlates the height of the\nliquid energy barrier with the slope of the specific heat in function of\ntemperature in accordance with the available data. These findings demonstrate\nthat the specific heat of liquids is controlled by the instantaneous normal\nmodes, i.e. by localized, unstable (exponentially decaying) vibrational\nexcitations, and provide the missing connection between anharmonicity, saddle\npoints in the energy landscape, and the thermodynamics of liquids.",
        "positive": "Scaling of the Splash Threshold for Low-Viscosity Fluids: The ambient gas pressure is determined for the onset of splashing of\nlow-viscosity liquid drops on smooth dry surfaces as we change the control\nparameters: drop impact velocity, drop radius, viscosity, surface tension,\ndensity, and gas molecular weight. This threshold pressure indicates that there\nare two distinct regimes when drop impact velocity is varied. By rescaling data\nusing functions of only three dimensionless numbers, the commonly used Reynolds\nand Weber numbers, as well as the ratio of drop radius to gas mean free path,\nall data is collapsed to a single curve that encompasses both regimes."
    },
    {
        "anchor": "Controlling the order of wedge filling transitions: the role of line\n  tension: We study filling phenomena in 3D wedge geometries paying particular attention\nto the role played by a line tension associated with the wedge bottom. Our\nstudy is based on transfer matrix analysis of an effective one dimensional\nmodel of 3D filling which accounts for the breather-mode excitations of the\ninterfacial height. The transition may be first-order or continuous (critical)\ndepending on the strength of the line tension associated with the wedge bottom.\nExact results are reported for the interfacial properties near filling with\nboth short-ranged (contact) forces and also van der Waals interactions. For\nsufficiently short-ranged forces we show the lines of critical and first-order\nfilling meet at a tricritical point. This contrasts with the case of dispersion\nforces for which the lines meet at a critical end-point. Our transfer matrix\nanalysis is compared with generalized random-walk arguments based on a necklace\nmodel and is shown to be a thermodynamically consistent description of\nfluctuation effects at filling. Connections with the predictions of conformal\ninvariance for droplet shapes in wedges is also made.",
        "positive": "Impact of polyelectrolyte adsorption on the rheology of concentrated\n  Poly(N-Isopropylacrylamide) microgel suspensions: We explore the impact of three water-soluble polyelectrolytes (PEs) on the\nflow of concentrated suspensions of poly(N-isopropylacrylamide) (PNIPAm)\nmicrogels with thermoresponsive anionic charge density. By progressively adding\nthe PEs to a jammed suspension of swollen microgels, we show that the rheology\nof the mixtures is remarkably influenced by the sign of the PE charge, PE\nconcentration and hydrophobicity only when the temperature is raised above the\nmicrogel volume phase transition temperature $T_c$, namely when microgels\ncollapse, they are partially hydrophobic and form a volume-spanning colloidal\ngel. We find that the original gel is strengthened close to the isoelectric\npoint, attained when microgels are mixed with cationic PEs, while PE\nhydrophobicity rules the gel strengthening at very high PE concentrations.\nSurprisingly, we find that polyelectrolyte adsorption or partial embedding of\nPE chains inside the microgel periphery occurs also when anionic polymers of\npolystyrene sulfonate with high degree of sulfonation are added. This gives\nrise to colloidal stabilization and to the melting of the original gel network\nabove $T_c$. Contrastingly, the presence of polyelectrolytes in suspensions of\nswollen, jammed microgels results in a weak softening of the original repulsive\nglass, even when an apparent isoelectric condition is met. Our study puts\nforward the crucial role of electrostatics in thermosensitive microgels,\nunveiling an exciting new way to tailor the flow of these soft colloids and\nhighlighting a largely unexplored path to engineer soft colloidal mixtures."
    },
    {
        "anchor": "A unified description of the rheology of hard-particle suspensions: The rheology of suspensions of Brownian, or colloidal, particles (diameter $d\n\\lesssim 1$ $\\mu$m) differs markedly from that of larger grains ($d \\gtrsim 50$\n$\\mu$m). Each of these two regimes has been separately studied, but the flow of\nsuspensions with intermediate particle sizes (1 $\\mu\\textrm{m} \\lesssim d\n\\lesssim 50$ $\\mu$m), which occur ubiquitously in applications, remains poorly\nunderstood. By measuring the rheology of suspensions of hard spheres with a\nwide range of sizes, we show experimentally that shear thickening drives the\ntransition from colloidal to granular flow across the intermediate size regime.\nThis insight makes possible a unified description of the (non-inertial)\nrheology of hard spheres over the full size spectrum. Moreover, we are able to\ntest a new theory of friction-induced shear thickening, showing that our data\ncan be well fitted using expressions derived from it.",
        "positive": "Networks and Hierarchies: How Amorphous Materials Learn to Remember: We consider the slow and athermal deformations of amorphous solids and show\nhow the ensuing sequence of discrete plastic rearrangements can be mapped onto\na directed network. The network topology reveals a set of highly connected\nregions joined by occasional one-way transitions. The highly connected regions\ninclude hierarchically organized hysteresis cycles and sub-cycles. At small to\nmoderate strains this organization leads to near-perfect return point memory.\nThe transitions in the network can be traced back to localized particle\nrearrangements (soft-spots) that interact via Eshelby-type deformation fields.\nBy linking topology to dynamics, the network representations provides new\ninsights into the mechanisms that lead to reversible and irreversible behavior\nin amorphous solids."
    },
    {
        "anchor": "Collective Sliding States for Colloidal Molecular Crystals: We study the driving of colloidal molecular crystals over periodic substrates\nsuch as those created with optical traps. The n-merization that occurs in the\ncolloidal molecular crystal states produces a remarkably rich variety of\ndistinct dynamical behaviors, including polarization effects within the pinned\nphase and the formation of both ordered and disordered sliding phases. Using\ncomputer simulations, we map the dynamic phase diagrams as a function of\nsubstrate strength for dimers and trimers on a triangular substrate, and\ncorrelate features on the phase diagram with transport signatures.",
        "positive": "The yielding of granular matter is marginally stable and critical: The mechanical yield of dense granular materials is a fascinating rheological\nphenomenon, beyond which stress no longer increases with strain at a\nsufficiently large deformation. Understanding the behavior of mechanical\nresponses associated with yielding is a fundamental goal in granular physics,\nand other related fields including glassy physics, material sciences,\ngeophysics, and active matter biophysics. However, despite nearly half a\ncentury of theoretical efforts, the nature of yielding in amorphous solids\nremains largely elusive compared to its crystalline counterpart. Here, we\nexperimentally investigate the mechanical responses of two-dimensional\nbidisperse jammed disks subjected to volume-invariant pure shear, focusing on\nthe behavior of yielding. We show that the microscopic mechanical and\ngeometrical features of configurations under shear can be characterized by two\ncritical exponents of weak-force and small-gap distributions originally\nproposed for the isotropic jamming transition. We find that the yielding\ntransition satisfies the condition of marginal mechanical stability through a\nscaling relationship between the two exponents, and after yielding global\ninstability emerges. The criticality of yielding is revealed by a significant\npeak of susceptibility that quantifies the fluctuation of a glass overlap order\nparameter. Moreover, we find a distinct transition before yielding, which is\nassociated with the onset of structural anisotropy."
    },
    {
        "anchor": "Extreme resistance of super-hydrophobic surfaces to impalement:\n  reversible electrowetting related to the impacting/bouncing drop test: The paper reports on the comparison of the wetting properties of\nsuper-hydrophobic silicon nanowires (NWs), using drop impact impalement and\nelectrowetting (EW) experiments. A correlation between the resistance to\nimpalement on both EW and drop impact is shown. From the results, it is evident\nthat when increasing the length and density of NWs: (i) the thresholds for drop\nimpact and EW irreversibility increase (ii) the contact-angle hysteresis after\nimpalement decreases. This suggests that the structure of the NWs network could\nallow for partial impalement, hence preserving the reversibility, and that EW\nacts the same way as an external pressure. The most robust of our surfaces show\na threshold to impalement higher than 35 kPa, while most of the\nsuper-hydrophobic surfaces tested so far have impalement threshold smaller than\n10 kPa.",
        "positive": "Numerical analysis of Pickering emulsion stability: insights from ABMD\n  simulations: The issue of the stability of Pickering emulsions is tackled at a mesoscopic\nlevel using dissipative particle dynamics simulations within the Adiabatic\nBiased Molecular Dynamics framework. We consider the early stage of the\ncoalescence process between two spherical water droplets in decane solvent. The\ndroplets are stabilized by Janus nanoparticles of different shapes (spherical\nand ellipsoidal) with different three-phase contact angles. Given a\nsufficiently dense layer of particles on the droplets, we show that the\nstabilization mechanism strongly depends on the collision speed. This is\nconsistent with a coalescence mechanism governed by the rheology of the\ninterfacial region. When the system is forced to coalesce sufficiently slowly,\nwe investigate at a mesoscopic level how the ability of the nanoparticles to\nstabilize Pickering emulsions is discriminated by nanoparticle mobility and the\nassociated caging effect. These properties are both related to the\ninterparticle interaction and the hydrodynamic resistance in the liquid film\nbetween the approaching interfaces."
    },
    {
        "anchor": "Polymer brushes with reversibly tunable grafting density: We propose a novel class of responsive polymer brushes, where the effective\ngrafting density can be controlled by external stimuli. This is achieved by\nusing end-grafted polymer chains that have an affinity to the substrate. For\nsufficiently strong surface interactions, a fraction of chains condenses into a\nnear-surface layer, while the remaining ones form the outer brush. The dense\nlayer and the more tenuous outer brush can be seen as coexisting microphases.\nThe effective grafting density of the outer brush is controlled by the\nadsorption strength and can be changed reversibly and in a controlled way as a\nresponse to changes in environmental parameters. The effect is demonstrated by\nnumerical SCF calculations and analyzed by scaling arguments. Since the\nthickness of the denser layer is about a few monomer sizes, its capacity to\nform a microphase is limited by the product of the brush chain length and the\ngrafting density. We explore the range of chain lengths and grafting densities\nwhere the effect is most pronounced. In this range, the SCF studies suggest\nthat individual chains inside the brush show large rapid fluctuations between\ntwo states that are separated by only a small free energy barrier. The behavior\nof the brush as a whole, however, does not reflect these large fluctuations,\nand the effective grafting density varies smoothly as a function of the control\nparameters.",
        "positive": "Charge renormalization and phase separation in colloidal suspensions: We explore the effects of counterion condensation on fluid-fluid phase\nseparation in charged colloidal suspensions. It is found that formation of\ndouble layers around the colloidal particles stabilizes suspensions against\nphase separation. Addition of salt, however, produces an instability which, in\nprinciple, can lead to a fluid-fluid separation. The instability, however, is\nso weak that it should be impossible to observe a fully equilibrated\ncoexistence experimentally."
    },
    {
        "anchor": "Water-induced self-oscillatory processes in colloidal systems by the\n  example of instant coffee: Slow long-lived fluctuations of mechanical properties of drying drops of\ninstant coffee water solutions have been found by means of the Drying Drop\nTechnology developed earlier. Parameters of the fluctuations depended on the\nextent of dilution and were not affected by additional hashing of the solution,\nclosing by a cover and shielding from external electromagnetic fields [1-3].\nHere we compared dynamics of physicochemical and morphological processes in\nbulk. We observed microscopically periodic emergence, growth, aggregation and\ndisappearance of spherical cavities (50-250 micrometers in diameter) in bulk of\ndispersion, which was followed by agreed fluctuations of physicochemical\nparameters of the colloidal system. We have shown that those spheres were huge\nhydrate covers of liquid crystal water around colloidal particles. Phase\ntransitions between free and bound (liquid crystal) water in a bulk of a\ncolloidal system is a pacemaker of fluctuations of its physicochemical\nproperties. These changes are regulated and coordinated by the value of osmotic\npressure. At low osmotic pressure hydrate covers grow, forcing out particles\nand ions into the bulk; at high osmotic pressure they collapse to small size,\nreducing osmotic pressure. Existence of self-oscillatory processes was\nconfirmed by a mathematical model.",
        "positive": "A model for the atomic-scale structure of a dense, nonequilibrium fluid:\n  the homogeneous cooling state of granular fluids: It is shown that the equilibrium Generalized Mean Spherical Model of fluid\nstructure may be extended to nonequilibrium states with equation of state\ninformation used in equilibrium replaced by an exact condition on the two-body\ndistribution function. The model is applied to the homogeneous cooling state of\ngranular fluids and upon comparison to molecular dynamics simulations is found\nto provide an accurate picture of the pair distribution function."
    },
    {
        "anchor": "Characterizing the fluid-matrix affinity in an organogel from the growth\n  dynamics of oil stains on blotting paper: Grease, as used for lubrication of rolling bearings, is a two-phase organogel\nthat slowly releases oil from its gelator matrix. Because the rate of release\ndetermines the operation time of the bearing, we study this release process by\nmeasuring the amount of extracted oil as a function of time, while we use\nabsorbing paper, to speed up the process. The oil concentration in the\nresulting stain is determined by measuring the attenuation of light transmitted\nthrough the paper, using a modified Lambert-Beer law. For grease the timescale\nfor paper imbibition is typically 2 orders of magnitude larger than for a bare\ndrop of the same base oil. This difference results from the high affinity, \\it\ni.e. wetting energy per unit volume, of the oil for the grease matrix. To\nquantify this affinity, we developed a Washburn-like model describing the oil\nflow from the porous grease into the paper pores. The stain radius versus time\ncurves for greases at various levels of oil content collapse onto a single\nmaster curve, which allows us to extract a characteristic spreading time and\nthe corresponding oil-matrix affinity. Lowering the oil content results in a\nsmall increase of the oil-matrix affinity yet in a significant change in the\nspreading timescale. Even an affinity increase by a few per mill doubles the\ntimescale.",
        "positive": "Transport of Brownian particles confined to a weakly corrugated channel: We investigate the average velocity of Brownian particles driven by a\nconstant external force when constrained to move in two-dimensional,\nweakly-corrugated channels. We consider both the geometric confinement of the\nparticles between solid walls as well as the soft confinement induced by a\nperiodic potential. Using perturbation methods we show that the leading order\ncorrection to the marginal probability distribution of particles in the case of\nsoft confinement is equal to that obtained in the case of geometric\nconfinement, provided that the (configuration) integral over the cross-section\nof the confining potential is equal to the width of the solid channel. We then\ncalculate the probability distribution and average velocity in the case of a\nsinusoidal variation in the width of the channels. The reduction on the average\nvelocity is larger in the case of soft channels at small P\\'eclet numbers and\nfor relatively narrow channels and the opposite is true at large P\\'eclet\nnumbers and for wide channels. In the limit of large P\\'eclet numbers the\nconvergence to bulk velocity is faster in the case of soft channels. The\nleading order correction to the average velocity and marginal probability\ndistribution agree well with Brownian Dynamics simulations for the two types of\nconfinement and over a wide range of P\\'eclet numbers."
    },
    {
        "anchor": "Bias extension test on an unbalanced woven composite reinforcement:\n  Experiments and modeling via a second-gradient continuum approach: The classical continuum models used for the woven fabrics do not fully\ndescribe the whole set of phenomena that occur during the testing of those\nmaterials. This incompleteness is partially due to the absence of energy terms\nrelated to some micro-structural properties of the fabric and, in particular,\nto the bending stiffness of the yarns. To account for the most fundamental\nmicrostructure-related deformation mechanisms occurring in unbalanced\ninterlocks, a second-gradient, hyperelastic, initially orthotropic continuum\nmodel is proposed.\n  A constitutive expression for the strain energy density is introduced to\naccount for i) in-plane shear deformations, ii) highly different bending\nstiffnesses in the warp and weft directions and iii) fictive elongations in the\nwarp and weft directions which eventually describe the relative sliding of the\nyarns. Numerical simulations which are able to reproduce the experimental\nbehavior of unbalanced carbon interlocks subjected to a Bias Extension Test are\npresented. In particular, the proposed model captures the macroscopic\nasymmetric S-shaped deformation of the specimen, as well as the main features\nof the associated deformation patterns of the yarns at the mesoscopic scale.",
        "positive": "Entropic Elasticity of Double-Strand DNA Subject to Simple Spatial\n  Constraints: The aim of the present paper is the study of the entropic elasticity of the\ndsDNA molecule, having a cristallographic length L of the order of 10 to 30\npersistence lengths A, when it is subject to spatial obstructions. We have not\ntried to obtain the single molecule partition function by solving a\nSchodringer-like equation. We prefer to stay within a discretized version of\nthe WLC model with an added one-monomer potential, simulating the spatial\nconstraints. We derived directly from the discretized Boltzmann formula the\ntransfer matrix connecting the partition functions relative to adjacent\n\"effective monomers\". We have plugged adequate Dirac delta-functions in the\nfunctional integral to ensure that the monomer coordinate and the tangent\nvector are independent variables. The partition function is, then, given by an\niterative process which is both numerically efficient and physically\ntransparent. As a test of our discretized approach, we have studied two\nconfigurations involving a dsDNA molecule confined between a pair of parallel\nplates."
    },
    {
        "anchor": "How Real are Liquid Groundstates? Ultra-Fast Crystal Growth and the\n  Susceptibility of Energy Minima in Liquids: We calculate the degree to which the final structure of the local groundstate\nin a liquid is a function of the strength of a perturbing potential applied\nduring energy minimization. This structural susceptibility is shown to\ncorrelate well with the observed tendency of liquid adjacent to a crystal\ninterface to exhibit a crystalline groundstate, a feature that has been\nstrongly linked to the observation of ultra-fast crystal growth in pure metals\nand ionic melts. It is shown that the structural susceptibility increases\ndramatically as the interaction potential between atoms is softened.",
        "positive": "Pattern formation in binary fluid mixtures induced by short-range\n  competing interactions: Molecular dynamics simulations and integral equation calculations of a simple\nequimolar mixture of diatomic molecules and monomers interacting via attractive\nand repulsive short-range potentials show the existence of pattern formation\n(microheterogeneity), mostly due to depletion forces away from the demixing\nregion. Effective site-site potentials extracted from the pair correlation\nfunctions using an inverse Monte Carlo approach and an integral equation\ninversion procedure exhibit the features characteristic of a short-range\nattractive and long-range repulsive potential. When charges are incorporated\ninto the model, this becomes a coarse grained representation of a room\ntemperature ionic liquid, and as expected, intermediate range order becomes\nmore pronounced and stable."
    },
    {
        "anchor": "Stress correlations in glasses: We rigorously establish that, in disordered three-dimensional (3D) isotropic\nsolids, the stress autocorrelation function presents anisotropic terms that\ndecay as $1/r^3$ at long-range, with $r$ the distance, as soon as either\npressure or shear stress fluctuations are normal. By normal, we mean that the\nfluctuations of stress, as averaged over spherical domains, decay as the\ninverse domain volume. Since this property is required for macroscopic stress\nto be self-averaging, it is expected to hold generically in all glasses and we\nthus conclude that the presence of $1/r^3$ stress correlation tails is the rule\nin these systems. Our proof follows from the observation that, in an infinite\nmedium, when both material isotropy and mechanical balance hold, (i) the stress\nautocorrelation matrix is completely fixed by just two radial functions: the\npressure autocorrelation and the trace of the autocorrelation of stress\ndeviators; furthermore, these two functions (ii) fix the decay of the\nfluctuations of sphere-averaged pressure and deviatoric stresses for windows of\nincreasing volume. Our conclusion is reached because, due to the precise\nanalytic relation (i) fixed by isotropy and mechanical balance, the constraints\narising via (ii) from the normality of stress fluctuations demand the spatially\nanisotropic stress correlation terms to decay as $1/r^3$ at long-range. For the\nsake of generality, we also examine situations when stress fluctuations are not\nnormal.",
        "positive": "Algae-like Artificial Organic Phototactic Micro-swimmers: Phototaxis is a light driven self-locomotion of mass and a common phenomenon\nin motile organisms with varieties of motility such as in bacteria, algae, etc.\nIn naturally occurring organisms, mechanical force is generated utilising their\nmetabolic energy to propel and swim in presence of light, performing important\nbio-chemical reactions. Herein, we report a new class of micro-swimmers that\nexhibit captivating and complicated micro-swimming mediated colony formation\nproperties resembling green algae. A facile pyrolysis reaction is explored\nleading to homogeneous organic Nano-structures forming patterned\nself-assemblies among themselves. A delicate balance of colloid surface forms\ninteresting architectures such as dynamic colonies, thallus like patterning and\ncilia like micro-arms. In presence of weak light both positive and negative\nphototaxis are seen moving the micro-swimmers propelling towards and away from\nthe light respectively. During swimming helical motion and electrostatic\ninteractions of colloidal micro-swimmers with neighbouring assemblies are\nobserved. The nature of assembly formation is found to be fractal and can be\ndisintegrated using strong light. Strong exposure stimulates predominately fast\nnegative phototaxis leading to directional propulsion along the light path. All\nthese algae life-like behaviour of the colloidal carbonaceous lyophilic\ncolloids are stable in alcohol and can be reversibly discontinued with water\ndue to super-hydrophilicity. We therefore introduce a class of life-like\ncolloidal chemical architecture. Our discovery may entice studies for creation\nof a diverse programmable micro-swimmers for microscopic understanding and\nmanipulating collective effect of the assemblies for bio-mimetic and catalytic\napplications."
    },
    {
        "anchor": "Formation and Dissolution of Bacterial Colonies: Many organisms form colonies for a transient period of time to withstand\nenvironmental pressure. Bacterial biofilms are a prototypical example of such\nbehavior. Despite significant interest across disciplines, physical mechanisms\ngoverning the formation and dissolution of bacterial colonies are still poorly\nunderstood. Starting from a kinetic description of motile and interacting cells\nwe derive a hydrodynamic equation for their density on a surface. We use it to\ndescribe formation of multiple colonies with sizes consistent with experimental\ndata and to discuss their dissolution.",
        "positive": "On the Molecular Origin of the Cooperative Coil-to-globule Transition of\n  Poly(N-isopropylacrylamide) in Water: By means of atomistic molecular dynamics simulations we investigate the\nbehaviour of poly(N-isopropylacrylamide), PNIPAM, in water at temperatures\nbelow and above the lower critical solution temperature (LCST), including the\nundercooled regime. The transition between water soluble and insoluble states\nat the LCST is described as a cooperative process involving an intramolecular\ncoil-to-globule transition preceding the aggregation of chains and the polymer\nprecipitation. In this work we investigate the molecular origin of such\ncooperativity and the evolution of the hydration pattern in the undercooled\npolymer solution. The solution behaviour of an atactic 30-mer at high dilution\nis studied in the temperature interval from 243 to 323 K with a favourable\ncomparison to available experimental data. In the PNIPAM water soluble states\nwe detect a correlation between polymer segmental dynamics and diffusion motion\nof bound water, occurring with the same activation energy. Simulation results\nshow that below the coil-to-globule transition temperature PNIPAM is surrounded\nby a network of hydrogen bonded water molecules and that the cooperativity\narises from the structuring of water clusters in proximity to hydrophobic\ngroups. Differently, the perturbation of the hydrogen bond pattern involving\nwater and amide groups occurs above the transition temperature. Altogether\nthese findings reveal that even above the LCST PNIPAM remains largely hydrated\nand that the coil-to-globule transition is related with a significant\nrearrangement of the solvent in proximity of the surface of the polymer. The\ncomparison between the hydrogen bonding of water in the surrounding of PNIPAM\nisopropyl groups and in bulk displays a decreased structuring of solvent at the\nhydrophobic polymer-water interface across the transition temperature, as\nexpected because of the topological extension along the chain of such\ninterface."
    },
    {
        "anchor": "Charge Renormalization, Effective Interactions, and Thermodynamics of\n  Deionized Colloidal Suspensions: Thermodynamic properties of charge-stabilised colloidal suspensions depend\nsensitively on the effective charge of the macroions, which can be\nsubstantially lower than the bare charge in the case of strong\ncounterion-macroion association. A theory of charge renormalization is\nproposed, combining an effective one-component model of charged colloids with a\nthermal criterion for distinguishing between free and associated counterions.\nThe theory predicts, with minimal computational effort, osmotic pressures of\ndeionized suspensions of highly charged colloids in close agreement with\nlarge-scale simulations of the primitive model.",
        "positive": "Continuum limit of the vibrational properties of amorphous solids: The low-frequency vibrational and low-temperature thermal properties of\namorphous solids are markedly different from those of crystalline solids. This\nsituation is counter-intuitive because any solid material is expected to behave\nas a homogeneous elastic body in the continuum limit, in which vibrational\nmodes are phonons following the Debye law. A number of phenomenological\nexplanations have been proposed, which assume elastic heterogeneities, soft\nlocalized vibrations, and so on. Recently, the microscopic mean-field theories\nhave been developed to predict the universal non-Debye scaling law. Considering\nthese theoretical arguments, it is absolutely necessary to directly observe the\nnature of the low-frequency vibrations of amorphous solids and determine the\nlaws that such vibrations obey. Here, we perform an extremely large-scale\nvibrational mode analysis of a model amorphous solid. We find that the scaling\nlaw predicted by the mean-field theory is violated at low frequency, and in the\ncontinuum limit, the vibrational modes converge to a mixture of phonon modes\nfollowing the Debye law and soft localized modes following another universal\nnon-Debye scaling law."
    },
    {
        "anchor": "Unzipping Dynamics of Long DNAs: The two strands of the DNA double helix can be `unzipped' by application of\n15 pN force. We analyze the dynamics of unzipping and rezipping, for the case\nwhere the molecule ends are separated and re-approached at constant velocity.\nFor unzipping of 50 kilobase DNAs at less than about 1000 bases per second,\nthermal equilibrium-based theory applies. However, for higher unzipping\nvelocities, rotational viscous drag creates a buildup of elastic torque to\nlevels above kBT in the dsDNA region, causing the unzipping force to be well\nabove or well below the equilibrium unzipping force during respectively\nunzipping and rezipping, in accord with recent experimental results of Thomen\net al. [Phys. Rev. Lett. 88, 248102 (2002)]. Our analysis includes the effect\nof sequence on unzipping and rezipping, and the transient delay in buildup of\nthe unzipping force due to the approach to the steady state.",
        "positive": "All-dielectric one-dimensional periodic structures for total\n  omnidirectional reflection and partial spontaneous emission control: A remarkable property of one-dimensional all-dielectric periodic structures\nhas recently been reported, namely a one-dimensional lattice can totally\nreflect electromagnetic wave of any polarization at all angles within a\nprescribed frequency region. Unlike their metallic counterpart, such\nall-dielectric omnidirectional mirrors are nearly free of loss at optical\nfrequencies. Here we discuss the physics, design criteria and applications of\nthe thin-film all-dielectric omnidirectional mirror. The experimental\ndemonstration of the mirror is presented at optical frequencies."
    },
    {
        "anchor": "Precursor of a magnetic-field-induced liquid-liquid transition of oxygen: The acoustic properties of liquid oxygen have been studied up to 90 T by\nmeans of the ultrasound pulse-echo technique. A monotonic decrease of the sound\nvelocity and an asymptotic increase of the acoustic attenuation are observed by\napplying magnetic fields. An unusually large acoustic attenuation, that becomes\n20 times as large as the zero-field value, cannot be explained by the classical\ntheory. These results indicate strong fluctuations of antiferromagnetically\ncoupled local structures. We point out that the observed fluctuations are a\nprecursor of a liquid-liquid transition, from a low-susceptibility to a\nhigh-susceptibility liquid, which is characterized by a local-structure\nrearrangement.",
        "positive": "Medium dependence of asphaltene agglomeration inhibitor efficiency: Applying chemical additives (molecule inhibitors or dispersants) is one of\nthe common ways to control asphaltene agglomeration and precipitation. However,\nit is not clear why at some conditions the synthetic flocculation inhibitors as\nwell as resins not only do not inhibit the asphaltene agglomeration,, they may\nalso promote it, and why the increasing of the additive concentration may lead\nto the diminishing of their efficacy. To clarify this issue, in the present\nwork we have performed a set of vapor preassure osmometry experiments\ninvestigating the asphaltene agglomeration inhibition by commercial and new\ninhibitor molecules in toluene and o-diclorobenzene. Monte Carlo computer\nmodeling has been applied to interpret some unexpected trends of molar mass of\nthe Puerto Ceiba asphaltene clusters at different concentrations of inhibitor,\nassuming that inhibitors efficiency is directly related to their adsorption on\nthe surface of asphaltene or its complexes. It has been found that a\nself-assembly of inhibitor molecules, induced by relative lyophilic or\nlyophobic interactions, may be a reason of the inhibitor efficacy declining."
    },
    {
        "anchor": "Structure and dynamics of hyaluronic acid semidilute solutions: a\n  dielectric spectroscopy study: Dielectric spectroscopy is used to investigate fundamental length scales\ndescribing the structure of hyaluronic acid sodium salt (Na-HA) semidilute\naqueous solutions. In salt-free regime, the length scale of the relaxation mode\ndetected in MHz range scales with HA concentration as $c_\\mathrm{HA}^{-0.5}$\nand corresponds to the de Gennes-Pfeuty-Dobrynin correlation length of\npolyelectrolytes in semidilute solution. The same scaling was observed for the\ncase of long, genomic DNA. Conversely, the length scale of the mode detected in\nkHz range also varies with HA concentration as $c_\\mathrm{HA}^{-0.5}$ which\ndiffers from the case of DNA ($c_\\mathrm{DNA}^{-0.25}$). The observed behavior\nsuggests that the relaxation in the kHz range reveals the de Gennes-Dobrynin\nrenormalized Debye screening length, and not the average size of the chain, as\nthe pertinent length scale. Similarly, with increasing added salt the\nelectrostatic contribution to the HA persistence length is observed to scale as\nthe Debye length, contrary to scaling pertinent to the Odijk-Skolnick-Fixman\nelectrostatic persistence length observed in the case of DNA. We argue that the\nobserved features of the kHz range relaxation are due to much weaker\nelectrostatic interactions that lead to the absence of Manning condensation as\nwell as a rather high flexibility of HA as compared to DNA.",
        "positive": "Mesoscale computational protocols for the design of highly cooperative\n  bivalent macromolecules: The last decade has witnessed a swiftly increasing interest in the design and\nproduction of novel multivalent molecules as powerful alternatives for\nconventional antibodies in the fight against cancer and infectious diseases.\nHowever, while it is widely accepted that large-scale flexibility ($10-100$ nm)\nand free/constrained dynamics (100 ns $- \\mu$s) control the activity of such\nnovel molecules, computational strategies at the mesoscale still lag behind\nexperiments in optimizing the design of crucial features, such as the binding\ncooperativity (a.k.a. avidity).\n  In this study, we introduced different coarse-grained models of a\npolymer-linked, two-nanobody composite molecule, with the aim of laying down\nthe physical bases of a thorough computational drug design protocol at the\nmesoscale. We show that the calculation of suitable potentials of mean force\nallows one to apprehend the nature, range and strength of the thermodynamic\nforces that govern the motion of free and wall-tethered molecules. Furthermore,\nwe develop a simple computational strategy to quantify the\nencounter/dissociation dynamics between the free end of a wall-tethered\nmolecule and the surface, at the roots of binding cooperativity. This procedure\nallows one to pinpoint the role of internal flexibility and weak non-specific\ninteractions on the kinetic constants of the NB-wall encounter and\ndissociation. Finally, we quantify the role and weight of rare events, which\nare expected to play a major role in real-life situations, such as in the\nimmune synapse, where the binding kinetics is likely dominated by fluctuations."
    },
    {
        "anchor": "Analytically approximate solution to the VLE problem with the SRK\n  equation of state: Since a transcendental equation is involved in vapor liquid equilibrium (VLE)\ncalculations with a cubic equation of state (EoS), any exact solution has to be\ncarried out numerically with an iterative approach [1,2]. This causes\nsignificant wastes of repetitive human efforts and computing resources. Based\non a recent study [3] on the Maxwell construction [4] and the van der Waals EoS\n[5], here we propose a procedure for developing analytically approximate\nsolutions to the VLE calculation with the Soave-Redlich-Kwong (SRK) EoS [6] for\nthe entire coexistence curve. This procedure can be applied to any cubic EoS\nand thus opens a new area for the EoS study. For industrial applications, a\nsimple databank can be built containing only the coefficients of a newly\ndefined function and other thermodynamic properties will be obtained with\nanalytical forms. For each system there is only a one-time effort, and\ntherefore, the wastes caused by the repetitive efforts can be avoided. By the\nway, we also show that for exact solutions, the VLE problem with any cubic EoS\ncan be reduced to solving a transcendental equation with one unknown, which can\nsignificantly simplify the methods currently employed [2,7].",
        "positive": "Dissipative particle dynamics simulation plus slip-springs for entangled\n  polymers with various slip-spring densities: Slip-spring models are valuable tools for simulating entangled polymers,\nbridging the gap between bead-spring models with excluded volume and network\nmodels with presumed reptation motion. This study focuses on the DPD-SS\n(Dissipative Particle Dynamics - Slip-Spring) model, which introduces\nslip-springs into the standard DPD polymer model with soft-core interactions.\nBy systematically adjusting the fugacity of slip-springs, the density of\nslip-springs within the system is varied. Simulation results demonstrate the\ncompatibility of models with different slip-spring densities in terms of\ndiffusion and linear relaxation modulus when the average number of slip-springs\nper chain is the same. The conversion between DPD-SS models concerning length\nand time is achieved through Rouse scaling, which utilizes the average number\nof DPD beads between consecutive anchoring points of slip-springs.\nAdditionally, the modulus conversion is accomplished through the plateau\nmodulus that takes account of fluctuations around entanglement. Notably,\ndiffusion and relaxation modulus from the DPD-SS model align with those\nreported for standard Kremer-Grest and DPD models featuring strong repulsive\ninteractions."
    },
    {
        "anchor": "Capillary Sorting of Particles by Dip Coating: In this letter, we describe the capillary sorting of particles by size based\non dip coating. A substrate withdrawn from a liquid bath entrains a coating\nwhose thickness depends on the withdrawal speed and the liquid properties. If\nthe coating material contains particles, they will only be entrained when the\nviscous force pulling them with the substrate overcomes the opposing capillary\nforce at the deformable meniscus. This force threshold occurs at different\nliquid thicknesses for particles of different sizes. Here, we show that this\ndifference can be used to separate small particles from a mixed suspension\nthrough capillary filtration. In a bidisperse suspension, we observe three\ndistinct filtration regimes. At low capillary numbers, Ca, no particles are\nentrained in the liquid coating. At high Ca, all particle sizes are entrained.\nFor a range of capillary numbers between these two extremes, only the smallest\nparticles are entrained while the larger ones remain in the reservoir. We\nexplain how this technique can be applied to polydisperse suspension. We also\nprovide an estimate of the range of capillary number to separate particles of\ngiven sizes. The combination of this technique with the scalability and\nrobustness of dip coating makes it a promising candidate for high-throughput\nseparation or purification of industrial and biomedical suspensions.",
        "positive": "Nanoscale capillary wetting studied with dissipative particle dynamic: We demonstrate that Multi-Body Dissipative Particle Dynamics (MDPD) can be\nused as an efficient computational tool for the investigation of nanoscale\ncapillary impregnation of confined geometries. As an essential prerequisite, a\nnovel model for a solid-liquid interface in the framework of MDPD is\nintroduced, with tunable wetting behaviour and thermal roughening to reduce\nartificial density- and temperature oscillations. Within this model, the\nimpregnation dynamics of a water-like fluid into a nanoscale slit pore has been\nstudied. Despite the coarse graining implied with the model fluid, a sufficient\namount of non-equilibrium averaging can be achieved allowing for the extraction\nof useful information even from transient simulations, such as the dynamic\napparent contact angle. Although it is found to determine the capillary driving\ncompletely, it cannot be intepreted as a simple function of the capillary\nnumber."
    },
    {
        "anchor": "The determinism and boundedness of self-assembling structures: Self-assembly processes are widespread in nature, and lie at the heart of\nmany biological and physical phenomena. The characteristics of self-assembly\nbuilding blocks determine the structures that they form. Two crucial properties\nare the determinism and boundedness of the self-assembly. The former tells us\nwhether the same set of building blocks always generates the same structure,\nand the latter whether it grows indefinitely. These properties are highly\nrelevant in the context of protein structures, as the difference between\ndeterministic protein self-assembly and nondeterministic protein aggregation is\ncentral to a number of diseases. Here we introduce a graph theoretical approach\nthat can determine the determinism and boundedness for several geometries and\ndimensionalities of self-assembly more accurately and quickly than conventional\nmethods. We apply this methodology to a previously studied lattice\nself-assembly model and discuss generalizations to a wide range of other\nself-assembling systems",
        "positive": "Superionic state in double-layer capacitors with nanoporous electrodes: In the recent experiments [Chmiola et al, Science 313, 1760 (2006); Largeot\net al, J. Am. Chem. Soc. 130, 2730 (2008)] an anomalous increase of the\ncapacitance with a decrease of the pore size of a carbon-based porous electric\ndouble-layer capacitor has been observed. We explain this effect by the image\nforces which exponentially screen out the electrostatic interactions of ions in\nthe interior of a pore. Packing of ions of the same sign becomes easier and is\nmainly limited by steric interactions. We call this state `superionic' and\nsuggest a simple model to describe it. The model reveals a possibility of a\nvoltage-induced first-order transition between a cation(anion)-deficient phase\nand a cation(anion)-rich phase which manifests itself in a jump of capacitance\nas a function of voltage."
    },
    {
        "anchor": "Effects of Rotational Symmetry Breaking in Polymer-coated Nanopores: The statistical theory of polymers tethered around the inner surface of a\ncylindrical channel has traditionally employed the assumption that the\nequilibrium density of the polymers is independent of the azimuthal coordinate.\nHowever, simulations have shown that this rotational symmetry can be broken\nwhen there are attractive interactions between the polymers. We investigate the\nphases that emerge in these circumstances, and we quantify the effect of the\nsymmetry assumption on the phase behavior of the system. In the absence of this\nassumption, one can observe large differences in the equilibrium densities\nbetween the rotationally symmetric case and the non-rotationally symmetric\ncase. A simple analytical model is developed that illustrates the driving\nthermodynamic forces responsible for this symmetry breaking. Our results have\nimplications for the current understanding of the polymer behavior in\ncylindrical nanopores.",
        "positive": "Influence of Chain Structure and Swelling on the Elasticity of Rubbery\n  Materials: Localization Model Description: Classical network elasticity theories are based on the concept of flexible\nvolumeless polymers fixed into a network in which there are no excluded volume,\nor even topological interactions, and where the chains explore accessible\nconfigurations by Brownian motion. In this type of model, the elasticity of the\nnetwork derives from the entropic changes arising from a displacement of the\nnetwork junction positions. The shortcoming of this approach is clear from the\nobservation that unswollen rubbery materials are nearly incompressible,\nreflecting the existence of strong intermolecular interactions that restrict\nthe polymer chains to an exploration of their local tube-like molecular\nenvironments. The imposition of a deformation of these solid rubbery materials\nthen necessitates a consideration of how the local molecular packing\nconstraints become modified under deformation and the impact of these changes\non the macroscopic elasticity of the material as a whole. Many researchers have\nstruggled with this difficult problem, in the present paper we focus on the\nsimple localization model of rubber elasticity of Gaylord and Douglas, which\nprovides a simple minimal model for the network elasticity of rubbers having\nstrong intermolecular interactions in the dense polymer state. Particular\nemphasis is given in the implications of this model in describing how network\nelasticity changes with swelling by a solvent, a phenomenon where large\ndeviations from classical elasticity have been observed and a situation\nrelevant to numerous applications involving rubbery materials. We also discuss\nthe nature of entanglement based on the same packing picture and deduce general\nrelationships for entanglement in terms of molecular parameters and we find\nthat our predictions accord with recent experimental correlations relating\nchain molecular structure to the entanglement molecular mass"
    },
    {
        "anchor": "Curvature variation controls particle aggregation on fluid vesicles: Cellular membranes exhibit a large variety of shapes, strongly coupled to\ntheir function. Many biological processes involve dynamic reshaping of\nmembranes, usually mediated by proteins. This interaction works both ways:\nwhile proteins influence the membrane shape, the membrane shape affects the\ninteractions between the proteins. To study these membrane-mediated\ninteractions on closed and anisotropically curved membranes, we use colloids\nadhered to ellipsoidal membrane vesicles as a model system. We find that two\nparticles on a closed system always attract each other, and tend to align with\nthe direction of largest curvature. Multiple particles form arcs, or, at large\nenough numbers, a complete ring surrounding the vesicle in its equatorial\nplane. The resulting vesicle shape resembles a snowman. Our results indicate\nthat these physical interactions on membranes with anisotropic shapes can be\nexploited by cells to drive macromolecules to preferred regions of cellular or\nintracellular membranes, and utilized to initiate dynamic processes such as\ncell division. The same principle could be used to find the midplane of an\nartificial vesicle, as a first step towards dividing it into two equal parts.",
        "positive": "Growth of a bubble cloud in CO2-saturated water in microgravity: The diffusion-driven growth of a dense cloud of bubbles immersed in a\ngas-supersaturated liquid is a problem that finds applications in several\nmodern technologies such as solvent-exchange micro-reactors, nanotechnology or\nthe manufacturing of foamy materials. However, under Earth's gravity\nconditions, these dynamics can only be observed for a very limited time if the\ncloud is not attached to a surface, due to the action of buoyancy, i.e. of\ngravity effects. Here, we present experimental observations of the time\nevolution of dense bubble clouds growing in CO$_2$-supersaturated water in\nmicrogravity conditions. We report the existence of three regimes where the\nbubble cloud exhibits different growth rates. At short times, each bubble grows\nindependently following the Epstein--Plesset equation. Later on, bubbles start\nto interact with each other and their growth rate diminishes as they compete\nfor the available CO$_2$. When this happens, the growth rate slows down. This\noccurs earlier the deeper the bubble is in the cloud. Finally, at long times,\nonly those bubbles on the husk continue growing. These regimes may be\nqualitatively described by a mathematical model where each individual bubble\ngrows in the presence of a constellation of point mass sinks. Despite the model\nbeing only valid for dilute bubble clouds, its predictions are consistent with\nthe experimental observations, even though the bubble clouds we observe are\nrather dense."
    },
    {
        "anchor": "Non-Gaussian energy landscape of a simple model for strong\n  network-forming liquids: accurate evaluation of the configurational entropy: We present a numerical study of the statistical properties of the potential\nenergy landscape of a simple model for strong network-forming liquids. The\nmodel is a system of spherical particles interacting through a square well\npotential, with an additional constraint that limits the maximum number of\nbonds, $N_{\\rm max}$, per particle. Extensive simulations have been carried out\nas a function of temperature, packing fraction, and $N_{\\rm max}$. The dynamics\nof this model are characterized by Arrhenius temperature dependence of the\ntransport coefficients and by nearly exponential relaxation of dynamic\ncorrelators, i.e. features defining strong glass-forming liquids. This model\nhas two important features: (i) landscape basins can be associated with bonding\npatterns; (ii) the configurational volume of the basin can be evaluated in a\nformally exact way, and numerically with arbitrary precision. These features\nallow us to evaluate the number of different topologies the bonding pattern can\nadopt. We find that the number of fully bonded configurations, i.e.\nconfigurations in which all particles are bonded to $N_{\\rm max}$ neighbors, is\nextensive, suggesting that the configurational entropy of the low temperature\nfluid is finite. We also evaluate the energy dependence of the configurational\nentropy close to the fully bonded state, and show that it follows a logarithmic\nfunctional form, differently from the quadratic dependence characterizing\nfragile liquids. We suggest that the presence of a discrete energy scale,\nprovided by the particle bonds, and the intrinsic degeneracy of fully bonded\ndisordered networks differentiates strong from fragile behavior.",
        "positive": "Enhanced Self-organized Dewetting of Ultrathin Polymer Films under\n  Water-organic Solutions: Fabrication of Sub-micron Spherical Lens Arrays: Field-induced self-organized patterning in ultrathin (< 100 nm) polymer films\nproduces resolutions of the order of 10 {\\mu}m or more because of the high\nenergy penalty for the surface deformations on small scales. We propose here a\nvery simple but versatile method to fabricate sub-micron (~100 nm) ordered and\ntunable polymeric structures by self-organized room temperature dewetting of\nultrathin polystyrene films by minimizing the surface tension limitation. We\nillustrate this technique by fabricating sub-micron lens arrays of tunable\ncurvature. This is achieved by switching to controlled room temperature\ndewetting under an optimal mix of water, acetone and methyl-ethyl ketone (MEK).\nOrganic solvents used decrease the glass transition temperature, greatly\ndecrease the interfacial tension, intensify the field and increase the contact\nangle/aspect ratio of the resulting tunable nano-structures, without a\nconcurrent solubilization of PS owing to water being the majority phase in the\noutside mixture."
    },
    {
        "anchor": "Polymer crystal-melt interfaces and nucleation in polyethylene: Kinetic barriers cause polymers to crystallize incompletely, into nanoscale\nlamellae interleaved with amorphous regions. As a result, crystalline polymers\nare full of crystal-melt interfaces, which dominate their physical properties.\nThe longstanding theoretical challenge to understand these interfaces has new\nrelevance, because of accumulating evidence that polymer crystals often\nnucleate via a metastable, partially ordered \"rotator\" phase. To test this idea\nrequires a theory of the bulk and interfacial free energies of the critical\nnucleus. We present a new approach to the crystal-melt interface, which\nrepresents the amorphous region as a grafted brush of loops in a\nself-consistent pressure field. We combine this theory with estimates of bulk\nfree energy differences, to calculate nucleation barriers and rates via rotator\nversus crystal nuclei for polyethylene. We find rotator-phase nucleation is\nindeed favored throughout the temperature range where nucleation is observed.\nOur methods can be extended to other polymers.",
        "positive": "Different pathways in mechanical unfolding/folding cycle of a single\n  semiflexible polymer: Kinetics of conformational change of a semiflexible polymer under mechanical\nexternal field were investigated with Langevin dynamics simulations. It is\nfound that a semiflexible polymer exhibits large hysteresis in mechanical\nfolding/unfolding cycle even with a slow operation, whereas in a flexible\npolymer, the hysteresis almost disappears at a sufficiently slow operation.\nThis suggests that the essential features of the structural transition of a\nsemiflexible polymer should be interpreted at least on a two-dimensional phase\nspace. The appearance of such large hysteresis is discussed in relation to\ndifferent pathways in the loading and unloading processes. By using a minimal\ntwo-variable model, the hysteresis loop is described in terms of different\npathways on the transition between two stable states."
    },
    {
        "anchor": "Time-evolution stability of order parameters and phase diagrams of\n  bosons on optical lattice: Stemming from the Heisenberg equations of motion, we study the time-evolution\nstability of the order parameters for the cold atoms on optical lattices. The\nrequirement of this stability of the order parameters endows the phase diagram\nwith a fruitful structure in the superfluid phase. For the one-component\nBose-Hubbard model, we see that this stability of order parameter leads to a\nphysically receivable phase diagram. For two-component bosons, we show that the\nmolecules are preformed in the atomic superfluid and then condenses into a\nmolecular superfluid phase at a critical repulsive inter-species interaction,\nwhich resembles the pre-pairing mechanism in high $T_c$ superconductor of Cu-O\ncuprates.",
        "positive": "Triply-Periodic Smectics: Twist-grain-boundary phases in smectics are the geometrical analogs of the\nAbrikosov flux lattice in superconductors. At large twist angles, the nonlinear\nelasticity is important in evaluating their energetics. We analytically\nconstruct the height function of a pi/2 twist-grain-boundary phase in smectic-A\nliquid crystals, known as Schnerk's first surface. This construction, utilizing\nelliptic functions, allows us to compute the energy of the structure\nanalytically. By identifying a set of heretofore unknown defects along the\npitch axis of the structure, we study the necessary topological structure of\ngrain boundaries at other angles, concluding that there exist a set of\nprivileged angles and that the \\pi/2 and \\pi/3 grain boundary structures are\nparticularly simple."
    },
    {
        "anchor": "Active microphase separation in mixtures of microtubules and\n  tip-accumulating molecular motors: Mixtures of microtubules and molecular motors form active materials with\ndiverse dynamical behaviors that vary based on their constituents' molecular\nproperties. We map the non-equilibrium phase diagram of microtubules and\ntip-accumulating kinesin-4 molecular motors. We find that kinesin-4 can drive\neither global contractions or turbulent-like extensile dynamics, depending on\nthe concentrations of both microtubules and a bundling agent. We also observe a\nrange of spatially heterogeneous non-equilibrium phases, including finite-sized\nradial asters, 1D wormlike chains, extended 2D bilayers, and system-spanning 3D\nactive foams. Finally, we describe intricate kinetic pathways that yield\nmicrophase separated structures and arise from the inherent frustration between\nthe orientational order of filamentous microtubules and the positional order of\ntip-accumulating molecular motors. Our work shows that the form of active\nstresses and phases in cytoskeletal networks are not solely dictated by the\nproperties of individual motors and filaments, but are also contingent on the\nconstituent's concentrations and spatial arrangement.",
        "positive": "Scaling description of the yielding transition in soft amorphous solids\n  at zero temperature: Yield stress materials flow if a sufficiently large shear stress is ap-\nplied. Although such materials are ubiquitous and relevant for indus- try,\nthere is no accepted microscopic description of how they yield, even in the\nsimplest situations where temperature is negligible and where flow\ninhomogeneities such as shear bands or fractures are ab- sent. Here we propose\na scaling description of the yielding transition in amorphous solids made of\nsoft particles at zero temperature. Our description makes a connection between\nthe Herschel-Bulkley expo- nent characterizing the singularity of the flow\ncurve near the yield stress {\\Sigma}c, the extension and duration of the\navalanches of plasticity observed at threshold, and the density P(x) of soft\nspots, or shear transformation zones, as a function of the stress increment x\nbe- yond which they yield. We argue that the critical exponents of the yielding\ntransition can be expressed in terms of three independent exponents {\\theta},\ndf and z, characterizing respectively the density of soft spots, the fractal\ndimension of the avalanches, and their duration. Our description shares some\nsimilarity with the depinning transition that occurs when an elastic manifold\nis driven through a random potential, but also presents some striking\ndifferences. We test our arguments in an elasto-plastic model, an automaton\nmodel similar to those used in depinning, but with a different interaction\nkernel, and find satisfying agreement with our predictions both in two and\nthree dimensions."
    },
    {
        "anchor": "Reconfigurable Artificial Microswimmers with Internal Feedback: Micron-size self-propelling particles are often proposed as synthetic models\nfor biological microswimmers, yet they lack internally regulated adaptation,\nwhich is central to the autonomy of their biological counterparts. Conversely,\nadaptation and autonomy can be encoded in larger-scale soft-robotic devices,\nbut transferring these capabilities to the colloidal scale remains elusive.\nHere, we create a new class of responsive microswimmers, powered by\ninduced-charge electrophoresis, which can adapt their motility to external\nstimuli via an internal feedback. Using sequential capillary assembly, we\nfabricate deterministic colloidal clusters comprising soft thermoresponsive\nmicroparticles, which, upon spontaneous reconfiguration, induce motility\nchanges, such as adaptation of the clusters' propulsion velocity and reversal\nof its direction. We rationalize the response in terms of a coupling between\nself-propulsion and variations of particle shape and dielectric properties.\nHarnessing those allows for strategies to achieve local dynamical control with\nsimple illumination patterns, revealing exciting opportunities for the\ndevelopment of new tactic active materials.",
        "positive": "Effect of pinning on the yielding transition of amorphous solids: Using numerical simulations, we have studied the yielding response, in the\nathermal quasi static limit, of a model amorphous material having inclusions in\nthe form of randomly pinned particles. We show that, with increasing pinning\nconcentration, the plastic activity becomes more spatially localized, resulting\nin smaller stress drops, and corresponding increase in the magnitude of strain\nwhere yielding occurs. We demonstrate that, unlike the spatially heterogeneous\nand avalanche led yielding in the case of the unpinned glass, for the case of\nlarge pinning concentration, yielding takes place via a spatially homogeneous\nproliferation of localized events."
    },
    {
        "anchor": "Energy dissipation in high speed impact on granular media: In this work, we thoroughly investigate the impact process on the granular\nmedia in the limit when the ratio of the impact velocity to the acoustic speed\nbecomes of the order of 0.01-1, which is far greater than the existing\nliterature (0.0001-0.001). We show that the energy dissipation is largely due\nto the energy cost associated with the exploration between different metastable\nstates via large scale reorganization of the force chain network. In this\nregime, the conventional drag force models break down, and the drag force can\nnot be decomposed into a depth dependent static pressure and a depth\nindependent inertial drag as proposed in the existing literature. The high\ndynamical stress generates acoustic pulses, which propagate longer distances\nrather than decaying exponentially, as observed in the previous works. In the\nlatter stage of the impact process, the boundary also plays an essential role\nin the reorganization of the force chains as the reflected acoustic pulses\ninteract with the original impact pulses. Furthermore, we study the scaling of\nthe early stage peak forces with the impact velocity and find that spatial\ndimensionality strongly influences the scaling.",
        "positive": "Disconnecting structure and dynamics in glassy thin films: Nanometrically thin glassy films depart strikingly from the behavior of their\nbulk counterparts. We investigate whether the dynamical differences between\nbulk and thin film glasses can be understood by differences in local\nmicroscopic structure. We employ machine-learning methods that have previously\nidentified strong correlations between local structure and particle\nrearrangement dynamics in bulk systems. We show that these methods completely\nfail to detect key aspects of thin-film glassy dynamics. Furthermore, we show\nthat no combination of local structural features drawn from a very general set\nof two- and multi-point functions is able to distinguish between particles at\nthe center of film and those in intermediate layers where the dynamics are\nstrongly perturbed."
    },
    {
        "anchor": "Surface Aggregate Structure of Nonionic Surfactants on Silica\n  Nanoparticles: The self-assembly of two nonionic surfactants, pentaethylene glycol\nmonododecyl ether (C12E5) and n-dodecyl-{\\ss}-maltoside ({\\ss}-C12G2), in the\npresence of a purpose-synthesized silica sol of uniform particle size (diameter\n16 nm) has been studied by adsorption measurements, dynamic light scattering\nand small-angle neutron scattering (SANS) using a H2O/D2O mixture matching the\nsilica, in order to highlight the structure of the surfactant aggregates. For\nC12E5 strong aggregative adsorption onto the silica beads, with a high plateau\nvalue of the adsorption isotherm above the CMC was found. SANS measurements\nwere made at a series of loadings, from zero surfactant up to maximum surface\ncoverage. It is found that the spherical core-shell model nicely reproduces the\nSANS data up to and including the local maximum at q = 0.42 nm-1 but not in the\nPorod region of high q, indicating that the surface area of the adsorbed\nsurfactant is underestimated by the model of a uniform adsorbed layer. A\nsatisfactory representation of the entire scattering profiles is obtained with\nthe model of micelle-decorated silica beads, indicating that C12E5 is adsorbed\nas spherical micellar aggregates. This behaviour is attributed to the high\nsurface curvature of the silica which prevents an effective packing of the\nhydrophobic chains of the amphiphile in a bilayer configuration. For the\nmaltoside surfactant {\\ss}-C12G2 very weak adsorption on the silica beads was\nfound. The SANS profile indicates that this surfactant forms oblate ellipsoidal\nmicelles in the silica dispersion, as in the absence of the silica beads.",
        "positive": "Mapping dynamical heterogeneity in structural glasses to correlated\n  fluctuations of the time variables: Dynamical heterogeneities -- strong fluctuations near the glass transition --\nare believed to be crucial to explain much of the glass transition\nphenomenology. One possible hypothesis for their origin is that they emerge\nfrom soft (Goldstone) modes associated with a broken continuous symmetry under\ntime reparametrizations. To test this hypothesis, we use numerical simulation\ndata from four glass-forming models to construct coarse grained observables\nthat probe the dynamical heterogeneity, and decompose the fluctuations of these\nobservables into two transverse components associated with the postulated\ntime-fluctuation soft modes and a longitudinal component unrelated to them. We\nfind that as temperature is lowered and timescales are increased, the time\nreparametrization fluctuations become increasingly dominant, and that their\ncorrelation volumes grow together with the correlation volumes of the dynamical\nheterogeneities, while the correlation volumes for longitudinal fluctuations\nremain small."
    },
    {
        "anchor": "Mean Field Fluid Behavior of the Gaussian Core Model: We show that the Gaussian core model of particles interacting via a\npenetrable repulsive Gaussian potential, first considered by Stillinger (J.\nChem. Phys. 65, 3968 (1976)), behaves like a weakly correlated ``mean field\nfluid'' over a surprisingly wide density and temperature range. In the bulk the\nstructure of the fluid phase is accurately described by the random phase\napproximation for the direct correlation function, and by the more\nsophisticated HNC integral equation. The resulting pressure deviates very\nlittle from a simple, mean-field like, quadratic form in the density, while the\nlow density virial expansion turns out to have an extremely small radius of\nconvergence. Density profiles near a hard wall are also very accurately\ndescribed by the corresponding mean-field free-energy functional. The binary\nversion of the model exhibits a spinodal instability against de-mixing at high\ndensities. Possible implications for semi-dilute polymer solutions are\ndiscussed.",
        "positive": "Salt-induced changes of colloidal interactions in critical mixtures: We report on salt-dependent interaction potentials of a single charged\nparticle suspended in a binary liquid mixture above a charged wall. For\nsymmetric boundary conditions (BC) we observe attractive particle-wall\ninteraction forces which are similar to critical Casimir forces previously\nobserved in salt-free mixtures. However, in case of antisymmetric BC we find a\ntemperature-dependent crossover from attractive to repulsive forces which is in\nstrong contrast to salt-free conditions. Additionally performed small-angle\nx-ray scattering experiments demonstrate that the bulk critical fluctuations\nare not affected by the addition of salt. This suggests that the observed\ncrossover can not be attributed alone to critical Casimir forces. Instead our\nexperiments point towards a possible coupling between the ionic distributions\nand the concentration profiles in the binary mixture which then affects the\ninteraction potentials in such systems."
    },
    {
        "anchor": "Polymer Network Diffusion in Charged Gels: The swelling kinetics of charged polymer gels reflect the complex competition\namong elastic, mixing, and ionic contributions. Here, we used dynamic light\nscattering to investigate the collective diffusion coefficient of model gels,\nwhose polymer network structure was controlled so that the three contributions\nwere comparable. We demonstrate that the collective diffusion coefficient stems\nfrom the sum of elastic, mixing, and ionic contributions, without evident\ncross-correlations. The significant ionic contribution conforms to the Donnan\nequilibrium, which explains equilibrium electrical potential gradients in\nbiological systems.",
        "positive": "The evolution of vibrational excitations in glassy systems: The equations of the mode-coupling theory (MCT) for ideal liquid-glass\ntransitions are used for a discussion of the evolution of the\ndensity-fluctuation spectra of glass-forming systems for frequencies within the\ndynamical window between the band of high-frequency motion and the band of\nlow-frequency-structural-relaxation processes. It is shown that the strong\ninteraction between density fluctuations with microscopic wave length and the\narrested glass structure causes an anomalous-oscillation peak, which exhibits\nthe properties of the so-called boson peak. It produces an elastic modulus\nwhich governs the hybridization of density fluctuations of mesoscopic wave\nlength with the boson-peak oscillations. This leads to the existence of\nhigh-frequency sound with properties as found by X-ray-scattering spectroscopy\nof glasses and glassy liquids. The results of the theory are demonstrated for a\nmodel of the hard-sphere system. It is also derived that certain schematic MCT\nmodels, whose spectra for the stiff-glass states can be expressed by elementary\nformulas, provide reasonable approximations for the solutions of the general\nMCT equations."
    },
    {
        "anchor": "Beads on a string: Structure of bound aggregates of globular particles\n  and long polymer chains: Macroscopic properties of suspensions, such as those composed of globular\nparticles (e.g., colloidal or macromolecular), can be tuned by controlling the\nequilibrium aggregation of the particles. We examine how aggregation -- and,\nhence, macroscopic properties -- can be controlled in a system composed of both\nglobular particles and long, flexible polymer chains that reversibly bind to\none another. We base this on a minimal statistical mechanical model of a single\naggregate in which the polymer chain is treated either as ideal or\nself-avoiding, and, in addition, the globular particles are taken to interact\nwith one another via excluded volume repulsion. Furthermore, each of the\nglobular particles is taken to have one single site to which at most one\npolymer segment may bind. Within the context of this model, we examine the\nstatistics of the equilibrium size of an aggregate and, thence, the structure\nof dilute and semidilute suspensions of these aggregates. We apply the model to\nbiologically relevant aggregates, specifically those composed of macromolecular\nproteoglycan globules and long hyaluronan polymer chains. These aggregates are\nespecially relevant to the materials properties of cartilage and the\nstructure-function properties of perineuronal nets in brain tissue, as well as\nthe pericellular coats of mammalian cells.",
        "positive": "A Micro-mechanical Modelling of the Pressure Dependence of the Void\n  Index of a Granular Assembly:: This paper models the increase of density of a virgin loose granular sample\nsubmitted to a progressive axisymmetric compression (either isotropic or\nanisotropic) as an irreversible process which destroys the larger voids; a\nstatistical mechanics approach similar to the one proposed by Boutreux & de\nGennes is performed which leads to the equation of the density of normally\nconsolidated states as a function of pressure; this equation is in agreement\nwith experimental data and the typical variation of e (void index) or v\n(specific volume) vs. ln(p) ."
    },
    {
        "anchor": "Unzipping DNA by a periodic force: Hysteresis loops, Dynamical order\n  parameter, Correlations and Equilibrium curves: The unzipping of a double stranded DNA whose ends are subjected to a time\ndependent periodic force with frequency $\\omega$ and amplitude $G$ is studied\nusing Monte Carlo simulations. We obtain the dynamical order parameter, $Q$,\ndefined as the time average extension between the end monomers of two strands\nof the DNA over a period, and its probability distributions $P(Q)$ at various\nforce amplitudes and frequencies. We also study the time autocorrelations of\nextension and the dynamical order parameter for various chain lengths. The\nequilibrium force-distance isotherms were also obtained at various frequencies\nby using non-equilibrium work measurements.",
        "positive": "Foams in contact with solid boundaries: equilibrium conditions and\n  conformal invariance: A liquid foam in contact with a solid surface forms a two-dimensional foam on\nthe surface. We derive the equilibrium equations for this 2D foam when the\nsolid surface is curved and smooth, generalising the standard case of flat Hele\nShaw cells. The equilibrium conditions at the vertices in 2D, at the edges in\n3D, are invariant by conformal transformations. Regarding the films, conformal\ninvariance only holds with restrictions, which we explicit for 3D and flat 2D\nfoams. Considering foams confined in thin interstices between two non parallel\nplates, normal incidence and Laplace's law lead to an approximate equation\nrelating the plate profile to the conformal map. Solutions are given for the\nlogarithm and power laws in the case of constant pressure. The paper concludes\non a comparison with available experimental data."
    },
    {
        "anchor": "A general criterion for solid instability and its application to creases: A general force-perturbation-based criterion for solid instability is\nproposed, which can predict instability including crease without priori\nknowledge of instability configuration. The crease instability is analyzed in\ndetail, we found that the occurrence of solid instability does not always\ncorrespond to the non-positive definiteness of global stiffness matrix. An\nelement stiffness-based criterion based on material stiffness is proposed as a\nstronger criterion in order to fast determine the occurrence of instability.\nThis criterion has been shown to degenerate into the criterion for judging\ninstability of certain known phenomena, such as necking and shear band\nphenomena. Besides, instability in strongly anisotropic materials is also\npredicted by the element stiffness-based criterion.",
        "positive": "Elastohydrodynamics for soft solids with surface roughness: transient\n  effects: A huge number of technological and biological systems involves the lubricated\ncontact between rough surfaces of soft solids in relative accelerated motion.\nExamples include dynamical rubber seals and the human joints. In this study we\nconsider an elastic cylinder with random surface roughness in accelerated\nsliding motion on a rigid, perfectly flat (no roughness) substrate in a fluid.\nWe calculate the surface deformations, interface separation and the\ncontributions to the friction force and the normal force from the area of real\ncontact and from the fluid. The driving velocity profile as a function of time\nis assumed to be either a sine-function, or a linear multi-ramp function. We\nshow how the squeeze-in and squeeze-out processes, occurring in accelerated\nsliding, quantitatively affect the Stribeck curve with respect to the steady\nsliding. Finally, the theory results are compared to experimental data."
    },
    {
        "anchor": "Sodium Chloride, NaCl/\u03b5 : New Force Field: A new computational model for Sodium Chloride, the NaCl/{\\epsilon}, is\nproposed. The Force Fields employed here for the description of the NaCl is\nbased on a set of radial particle-particle pair potentials involving\nLennard-Jones (LJ) and Coulombic forces. The parameterization is obtained\nfitting the density of the crystal and the density and the dielectric constant\nof the mixture of salt with water at diluted solution. Our model shows good\nagreement with the experimental values for the density and surface tension for\nthe pure system and for the density, the viscosity, the diffusion, and the\ndielectric constant for the mixture with water at various molal concentrations.\nThe NaCl/{\\epsilon} together with the water TIP4P/{\\epsilon} model provide a\ngood approximation for studying electrolyte solutions.",
        "positive": "Colloidal transport through optical tweezer arrays: Viscously damped particles driven past an evenly spaced array of potential\nenergy wells or barriers may become kinetically locked in to the array, or else\nmay escape from the array. The transition between locked-in and free-running\nstates has been predicted to depend sensitively on the ratio between the\nparticles' size and the separation between wells. This prediction is confirmed\nby measurements on monodisperse colloidal spheres driven through arrays of\nholographic optical traps."
    },
    {
        "anchor": "Nematic textures in spherical shells: The equilibrium texture of nematic shells is studied as a function of their\nthickness. For ultrathin shells the ground state has four short 1/2\ndisclination lines but, as the thickness of the film increases, a three\ndimensional escaped configuration composed of two pairs of half-hedgehogs\nbecomes energetically favorable. We derive an exact solution for the nematic\nground state in the one Frank constant approximation and study the stability of\nthe corresponding texture against thermal fluctuations.",
        "positive": "Sagging Ropes Demonstrate the Transversality Conditions of Variational\n  Problems: An account of the transversality conditions of variational problems gives\nrise to essential results in the analysis of different physical phenomena. This\npowerful and elegant approach has proven to be fruitful in a diversity of\nvariational problems with free endpoints, when the endpoints are free to slip\nalong preset curves. We illustrate the transversality condition by the study of\na heavy inextensible rope sagging both symmetrically and asymmetrically between\ntwo steering variously-shaped guide wires without friction. In this case, the\ntransversality conditions lead to the orthogonality of the rope to the wires at\nendpoints of the rope, which is confirmed experimentally. Freeing the endpoints\nof the rope yields exact and simple analytical equations predicting the tension\nof the rope. Heavy ropes whose endpoints are free to slip between\nvariously-shaped wires are discussed."
    },
    {
        "anchor": "Controlling flow patterns and topology in active emulsions: Active emulsions and liquid crystalline shells are intriguing and\nexperimentally realisable types of topological matter. Here we numerically\nstudy the morphology and spatiotemporal dynamics of a double emulsion, where\none or two passive small droplets are embedded in a larger active droplet. We\nfind activity introduces a variety of rich and nontrivial nonequilibrium states\nin the system. First, a double emulsion with a single active droplet becomes\nself-motile, and there is a transition between translational and rotational\nmotion: both of these regimes remain defect-free, hence topologically trivial.\nSecond, a pair of particles nucleate one or more disclination loops, with\nconformational dynamics resembling a rotor or chaotic oscillator, accessed by\ntuning activity. In the first state a single, topologically charged,\ndisclination loop powers the rotation. In the latter state, this disclination\nstretches and writhes in 3D, continuously undergoing recombination to yield an\nexample of an active living polymer. These emulsions can be self-assembled in\nthe lab, and provide a pathway to form flow and topology patterns in active\nmatter in a controllable way, as opposed to bulk systems that typically yield\nactive turbulence.",
        "positive": "Re-entrant melting and freezing in a model system of charged colloids: We studied the phase behavior of charged and sterically stabilized colloids\nusing confocal microscopy in a less polar solvent (dielectric constant 5.4).\nUpon increasing the colloid volume fraction we found a transition from a fluid\nto a body centered cubic crystal at 0.0415+/-0.0005, followed by re-entrant\nmelting at 0.1165+/-0.0015. A second crystal of different symmetry, random\nhexagonal close-packed, was formed at a volume fraction around 0.5, similar to\nthat of hard spheres. We attribute the intriguing phase behavior to particle\ninteractions that depend strongly on volume fraction, mainly due to changes in\nthe colloid charge. In this low polarity system the colloids acquire charge\nthrough ion adsorption. The low ionic strength leads to fewer ions per colloid\nat elevated volume fractions and consequently a density-dependent colloid\ncharge."
    },
    {
        "anchor": "Fluidization and anomalous density fluctuations in epithelial tissues\n  with pulsating activity: Cells not only can have self-motility by crawling, but also are capable of\nother types of active motions like periodic contraction or pulsation. In this\nwork, by using the Voronoi cell model, we show how this non-motility activity\naffects the structure, dynamic and density fluctuations of cellular monolayers.\nWe found that random cell pulsation can fluidize solid epithelial tissues,\nresulting in a \\emph{hyperuniform} fluid state, while pulsation synchronization\ninhibits the fluidity, causes a reversed solidification. We prove this\nsolidification is BKT-type transition, characterized by strong density/dynamic\nheterogeneity arising from the creation of topological defects in the pulsating\nphase space. The magnitude and length scale of density heterogeneity diverge as\nthe pulsating period increases, resulting in an opposite \\emph{giant} density\nfluctuation. Our findings accord with recent experimental observations and can\nbe quantitatively explained by a proposed fluctuating hydrodynamic theory.",
        "positive": "An Asymmetric Elastic Rod Model for DNA: In this paper we consider the anharmonic corrections to the anisotropic\nelastic rod model for DNA. Our model accounts for the difference between the\nbending energies of positive and negative rolls, which comes from the\nasymmetric structure of the DNA molecule. We will show that the model can\nexplain the high flexibility of DNA at small length scales, as well as kink\nformation at high deformation limit."
    },
    {
        "anchor": "Bending stiff charged polymers: the electrostatic persistence length: Many charged polymers, including nucleic acids, are locally stiff. Their\nbending rigidity -- quantified by the persistence length --, depends crucially\non Coulombic features, such as the ionic strength of the solution which offers\na convenient experimental route for tuning the rigidity. While the classic\nOdijk-Skolnick-Fixman treatment fails for realistic parameter values, we derive\na simple analytical formula for the electrostatic persistence length. It is\nshown to be in remarkable agreement with numerically obtained Poisson-Boltzmann\ntheory results, thereby fully accounting for non-linearities, among which\ncounter-ion condensation effects. Specified to double-stranded DNA, our work\nreveals that the widely used bare persistence length of 500\\,\\AA\\ is\noverestimated by some 20%",
        "positive": "Spontaneous Oscillations of Elastic Filaments Induced by Molecular\n  Motors: It is known from the wave-like motion of microtubules in motility assays that\nthe piconewton forces that motors produce can be sufficient to bend the\nfilaments. In cellular phenomena such as cytosplasmic streaming, molecular\nmotors translocate along cytoskeletal filaments, carrying cargo which entrains\nfluid. When large numbers of such forced filaments interact through the\nsurrounding fluid, as in particular stages of oocyte development in\n$Drosophila~melanogaster$, complex dynamics are observed, but the detailed\nmechanics underlying them has remained unclear. Motivated by these\nobservations, we study here perhaps the simplest model for these phenomena: an\nelastic filament, pinned at one end, acted on by a molecular motor treated as a\npoint force. Because the force acts tangential to the filament, no matter what\nits shape, this \"follower-force\" problem is intrinsically non-variational, and\nthereby differs fundamentally from Euler buckling, where the force has a fixed\ndirection, and which, in the low Reynolds number regime, ultimately leads to a\nstationary, energy-minimizing shape. Through a combination of linear stability\ntheory, analytical study of a solvable simplified \"two-link\" model, and\nnumerical studies of the full elastohydrodynamic equations of motion we\nelucidate the Hopf bifurcation that occurs with increasing forcing of a\nfilament, leading to flapping motion analogous to the high Reynolds number\noscillations of a garden hose with a free end."
    },
    {
        "anchor": "DFT study of ionic liquids adsorption on circumcoronene shaped graphene: Carbon materials have a range of properties such as high electrical\nconductivity, high specific surface area, and mechanical flexibility are\nrelevant for electrochemical applications. Carbon materials are utilised in\nenergy conversion-and-storage devices along with electrolytes of complementary\nproperties. In this work, we study the interaction of highly concentrated\nelectrolytes (ionic liquids) at a model carbon surface (circumcoronene) using\ndensity functional theory methods. Our results indicate the decisive role of\nthe dispersion interactions that noticeably strengthen the circumcoronene-ion\ninteraction. Also, we focus on the adsorption of halide anions as the\nelectrolytes containing these ions are promising for practical use in\nsupercapacitors and solar cells.",
        "positive": "Elasticity of smectic liquid crystals with focal conic domains: We study the elastic properties of thermotropic smectic liquid crystals with\nfocal conic domains (FCDs). After the application of the controlled preshear at\ndifferent temperatures, we independently measured the shear modulus G' and the\nFCD size L. We find out that these quantities are related by the scaling\nrelation G' ~ \\gamma_{eff}/L where \\gamma_{eff} is the effective surface\ntension of the FCDs. The experimentally obtained value of \\gamma_{\\rm eff}\nshows the same scaling as the effective surface tension of the layered systems\n\\sqrt{KB} where K and B are the bending modulus and the layer compression\nmodulus, respectively. The similarity of this scaling relation to that of the\nsurfactant onion phase suggests an universal rheological behavior of the\nlayered systems with defects."
    },
    {
        "anchor": "Self-propulsion against a moving membrane: enhanced accumulation and\n  drag force: Self-propulsion (SP) is a main feature of active particles (AP), such as\nbacteria or biological micromotors, distinguishing them from passive colloids.\nA renowned consequence of SP is accumulation at static interfaces, even in the\nabsence of hydrodynamic interactions. Here we address the role of SP in the\ninteraction between AP and a moving semipermeable membrane. In particular, we\nimplement a model of noninteracting AP in a channel crossed by a partially\npenetrable wall, moving at a constant velocity $c$. With respect to both the\ncases of passive colloids with $c>0$ and AP with $c=0$, the AP with finite $c$\nshow enhancement of accumulation in front of the obstacle and experience a\nlargely increased drag force. This effect is understood in terms of an\neffective potential localised at the interface between particles and membrane,\nof height proportional to $c\\tau/\\xi$, where $\\tau$ is the AP's re-orientation\ntime and $\\xi$ the width characterising the surface's smoothness ($\\xi\\to 0$\nfor hard core obstacles). An approximate analytical scheme is able to reproduce\nthe observed density profiles and the measured drag force, in very good\nagreement with numerical simulations. The effects discussed here can be\nexploited for automatic selection and filtering of AP with desired parameters.",
        "positive": "Shear Viscosity of Clay-like Colloids in Computer Simulations and\n  Experiments: Dense suspensions of small strongly interacting particles are complex\nsystems, which are rarely understood on the microscopic level. We investigate\nproperties of dense suspensions and sediments of small spherical Al_2O_3\nparticles in a shear cell by means of a combined Molecular Dynamics (MD) and\nStochastic Rotation Dynamics (SRD) simulation. We study structuring effects and\nthe dependence of the suspension's viscosity on the shear rate and shear\nthinning for systems of varying salt concentration and pH value. To show the\nagreement of our results to experimental data, the relation between bulk pH\nvalue and surface charge of spherical colloidal particles is modeled by\nDebye-Hueckel theory in conjunction with a 2pK charge regulation model."
    },
    {
        "anchor": "Avalanches, precursors and finite size fluctuations in a mesoscopic\n  model of amorphous plasticity: We discuss avalanche and finite size fluctuations in a mesoscopic model to\ndescribe the shear plasticity of amorphous materials. Plastic deformation is\nassumed to occur through series of local reorganizations. Yield stress criteria\nare random while each plastic slip event induces a quadrupolar long range\nelastic stress redistribution. The model is discretized on a regular square\nlattice. Shear plasticity can be studied in this context as a depinning dynamic\nphase transition. We show evidence for a scale free distribution of avalanches\n$P(s)\\propto S^{-\\kappa}$ with a non trivial exponent $\\kappa \\approx 1.25$\nsignificantly different from the mean field result $\\kappa = 1.5$. Finite size\neffects allow for a characterization of the scaling invariance of the yield\nstress fluctuations observed in small samples. We finally identify a population\nof precursors of plastic activity and characterize its spatial distribution.",
        "positive": "Stable intermediate phase of secondary structures for semiflexible\n  polymers: Systematic microcanonical inflection-point analysis of precise numerical\nresults obtained in extensive generalized-ensemble Monte Carlo simulations\nreveals a bifurcation of the coil-globule transition line for polymers with a\nbending stiffness exceeding a threshold value. The region, enclosed by the\ntoroidal and random-coil phases, is dominated by structures crossing over from\nhairpins to loops upon lowering the energy. Conventional canonical statistical\nanalysis is not sufficiently sensitive to allow for the identification of these\nseparate phases."
    },
    {
        "anchor": "Path integrals for stiff polymers applied to membrane physics: Path integrals similar to those describing stiff polymers arise in the\nHelfrich model for membranes. We show how these types of path integrals can be\nevaluated and apply our results to study the thermodynamics of a minority\nstripe phase in a bulk membrane. The fluctuation induced contribution to the\nline tension between the stripe and the bulk phase is computed, as well as the\neffective interaction between the two phases in the tensionless case where the\ntwo phases have differing bending rigidities.",
        "positive": "Fluidisation of yield stress fluids under vibration: Motivated by the industrial processing of chocolate, we study experimentally\nthe fluidisation of a sessile drop of yield-stress fluid on a pre-existing\nlayer of the same fluid under vertical sinusoidal oscillations. We compare the\nbehaviours of molten chocolate and Carbopol which are both shear-thinning with\na similar yield stress but exhibit very different elastic properties. We find\nthat these materials spread when the forcing acceleration exceeds a threshold\nwhich is determined by the initial deposition process. However, they exhibit\nvery different spreading behaviours: whereas chocolate exhibits slow long-term\nspreading, the Carbopol drop rapidly relaxes its stress by spreading to a new\nequilibrium shape with an enlarged footprint. This spreading is insensitive to\nthe history of the forcing. In addition, the Carbopol drop performs\nlarge-amplitude oscillations with the forcing frequency, both above and below\nthe threshold. We investigate these viscoelastic oscillations and provide\nevidence of complex nonlinear viscoelastic behaviour in the vicinity of the\nspreading threshold. In fact, for forcing accelerations greater than the\nspreading threshold, our drop automatically adjusts its shape to remain at the\nyield stress. We discuss how our vibrated-drop experiment offers a new and\npowerful approach to probing the yield transition in elastoviscoplastic fluids."
    },
    {
        "anchor": "Aggregate Formation of Surface-Modified Nanoparticles in Solvents and\n  Polymer Nanocomposites: A new method based on the combination of small-anglescattering, reverse Monte\nCarlo simulations, and an aggregate recognition algorithm is proposed to\ncharacterize the structure of nanoparticle suspensions in solvents and polymer\nnanocomposites, allowing detailedstudies of the impact of different\nnanoparticle surface modifications.Experimental small-angle scattering is\nreproduced using simulated annealing of configurations of polydisperse\nparticles in a simulation box compatible with the lowest experimental q-vector.\nThen, properties of interest likeaggregation states are extracted from these\nconfigurations and averaged. This approach has been applied to silane\nsurface-modified silica nanoparticles with different grafting groups, in\nsolvents and after casting into polymer matrices.It is shown that the chemistry\nof the silane function, in particular mono- or trifunctionality possibly\nrelated to patch formation, affects the dispersion state in a given medium, in\nspite of an unchanged alkylchain length. Our approach may be applied to study\nany dispersion or aggregation state of nanoparticles. Concerningnanocomposites,\nthe method has potential impact on the design of new formulations allowing\ncontrolled tuning of nanoparticle dispersion.",
        "positive": "Frequency-dependent hydrodynamic finite size correction in molecular\n  simulations reveals the long-time hydrodynamic tail: Finite-size effects are challenging in molecular dynamics simulations because\nthey have significant effects on computed static and dynamic properties, in\nparticular diffusion constants, friction coefficients and time- or\nfrequency-dependent response functions. We investigate the influence of\nperiodic boundary conditions on the velocity autocorrelation function and the\nfrequency-dependent friction of a particle in a fluid and show that the\nlong-time behavior (starting at the picosecond timescale) is significantly\naffected. We develop an analytical correction allowing to subtract the periodic\nboundary condition effects. By this we unmask the power-law long-time tails of\nthe memory kernel and the velocity autocorrelation function in liquid water and\na Lennard-Jones fluid from rather small simulation boxes."
    },
    {
        "anchor": "Experimental study of forces between quasi-two-dimensional emulsion\n  droplets near jamming: We experimentally study the jamming of quasi-two-dimensional emulsions. Our\nexperiments consist of oil-in-water emulsion droplets confined between two\nparallel plates. From the droplet outlines, we can determine the forces between\nevery droplet pair to within 8% over a wide range of area fractions $\\phi$. We\nstudy three bidisperse samples that jam at area fractions $\\phi_c \\approx\n0.86$. Our data show that for $\\phi > \\phi_c$, the contact numbers and pressure\nhave power-law dependence on $\\phi-\\phi_c$ in agreement with the critical\nscaling found in numerical simulations. Furthermore, we see a link between the\ninterparticle force law and the exponent for the pressure scaling, supporting\nprior computational observations. We also observe linear-like force chains\n(chains of large inter-droplet forces) that extend over 10 particle lengths,\nand examine the origin of their linearity. We find that the relative\norientation of large force segments are random and that the tendency for force\nchains to be linear is not due to correlations in the direction of neighboring\nlarge forces, but instead occurs because the directions are biased towards\nbeing linear to balance the forces on each droplet.",
        "positive": "Shear jamming and fragility of suspensions in a continuum model with\n  elastic constraints: Under an applied traction, highly concentrated suspensions of solid particles\nin fluids can turn from a state in which they flow to a state in which they\ncounteract the traction as an elastic solid: a shear-jammed state. Remarkably,\nthe suspension can turn back to the flowing state simply by inverting the\ntraction. A tensorial model is presented and tested in paradigmatic cases. We\nshow that, to reproduce the phenomenology of shear jamming in generic\ngeometries, it is necessary to link this effect to the elastic response\nsupported by the suspension microstructure rather than to a divergence of the\nviscosity."
    },
    {
        "anchor": "Crystalline clusters in mW water: stability, growth, and grain\n  boundaries: With numerical simulations of the mW model of water, we investigate the\nenergetic stability of crystalline clusters for both Ice I (cubic and hexagonal\nice) and for the metastable Ice 0 phase as a function of the cluster size.\nUnder a large variety of forming conditions, we find that the most stable\ncluster changes as a function of size: at small sizes the Ice 0 phase produces\nthe most stable clusters, while at large sizes there is a crossover to Ice I\nclusters. We further investigate the growth of crystalline clusters with the\nseeding technique and study the growth patterns of different crystalline\nclusters. While energetically stable at small sizes, the growth of metastable\nphases (cubic and Ice 0) is hindered by the formation of coherent grain\nboundaries. A five-fold symmetric twin boundary for cubic ice, and a newly\ndiscovered coherent grain boundary in Ice 0, that promotes cross nucleation of\ncubic ice. Our work reveals that different local structures can compete with\nthe stable phase in mW water, and that the low energy cost of particular grain\nboundaries might play an important role in polymorph selection.",
        "positive": "Self-assembly of liquid crystal block copolymer PEG-b-smectic polymer in\n  pure state and in dilute aqueous solution: A series of amphiphilic LC block copolymers, in which the hydrophobic block\nis a smectic polymer poly(4-methoxyphenyl 4-(6-acryloyloxy-hexyloxy)-benzoate)\n(PA6ester1) and the hydrophilic block is polyethyleneglycol (PEG), were\nsynthesized and characterized. The self-assembly of one of them in both the\npure state and the dilute aqueous solution was investigated in detail.\nNano-structures in the pure state were studied by SAXS and WAXS on samples\naligned by a magnetic field. A hexagonal cylindrical micro-segregation phase\nwas observed with a lattice distance of 11.2 nm. The PEG blocks are in the\ncylinder, while the smectic polymer blocks form a matrix with layer spacing 2.4\nnm and layer normal parallel to the long axis of the cylinders. Faceted\nunilamellar polymer vesicles, polymersomes, were formed in water, as revealed\nby cryo-TEM. In the lyotropic bilayer membrane of these polymersomes, the\nthermotropic smectic order in the hydrophobic block is clearly visible with\nlayer normal parallel to the membrane surface."
    },
    {
        "anchor": "Revisiting stress propagation in a two-dimensional elastic circular disk\n  under diametric loading: In this paper, we present a comprehensive investigation of stress propagation\nin a two-dimensional elastic circular disk. To accurately describe the\ndisplacements and stress fields within the disk, we employ a scalar and vector\npotential approach, representing them as sums of Bessel functions. The\ndetermination of the coefficients for these expansions is accomplished in the\nLaplace space, where we compare the boundary conditions. By converting the\ninverse Laplace transforms into complex integrals using residue calculus, we\nsuccessfully derive explicit expressions for the displacements and stress\nfields. Notably, these expressions encompass primary, secondary, and surface\nwaves, providing a thorough characterization of the stress propagation\nphenomena within the disk. Our findings contribute to the understanding of\nmechanical behavior in disk-shaped components and can be valuable in the design\nand optimization of such structures across various engineering disciplines.",
        "positive": "Swelling Dynamics of a Disk-Shaped Gel: When a gel absorbs solvent from surrounding, stress field is created in the\ngel, and this causes complex dynamics of the swelling behavior. Here we study\nthis effect for disk-shaped gel by rigorously solving the diffusio-mechanical\ncoupling equation. We show that (a) while the macroscopic thickness and the\nradius of the gel increases monotonically in time, the gel is compressed near\nthe mid-plane, and that (b) while the swelling time depends on the shear\nmodulus $G$ of the gel, its dependence is weak, and the time is mainly\ndetermined by the friction constant of the gel network and the osmotic bulk\nmodulus of the gel. We also show that these characteristic features are\nreproduced accurately by a simple variational calculation for the gel\ndeformation. An analytical expression is given for the swelling time."
    },
    {
        "anchor": "Mesoscale solubilization and critical phenomena in binary and quasi\n  binary solutions of hydrotropes: Hydrotropes are substances consisting of amphiphilic molecules that are too\nsmall to self assemble in equilibrium structures in aqueous solutions, but can\nform dynamic molecular clusters H bonded with water molecules. Some\nhydrotropes, such as low molecular weight alcohols and amines, can solubilize\nhydrophobic compounds in aqueous solutions at a mesoscopic scale, around 100\nnm, with formation of long lived mesoscale droplets. In this work, we report on\nthe studies of near critical and phase behavior of binary, 2,6-lutidine - H2O,\nand quasibinary, 2,6-lutidine - H2O - D2O, and tert-butanol - 2-butanol - H2O\nsolutions in the presence of a solubilized hydrophobic impurity, cyclohexane.\nIn additional to visual observation of fluid phase equilibria, two experimental\ntechniques were used - light scattering and small - angle neutron scattering.\nIt was found that the increase of the tert-butanol to 2-butanol ratio affects\nthe liquid - liquid equilibria in the quasi-binary system at ambient pressure\nin the same way as the increase of pressure modifies the phase behavior of\nbinary 2-butanol - H2O solutions. The correlation length of critical\nfluctuations near the liquid-liquid separation and the size of mesoscale\ndroplets of solubilized cyclohexane were obtained by dynamic light scattering\nand by small - angle neutron scattering. It is shown that the effect of the\npresence of small amounts of cyclohexane on the near - critical phase behavior\nis twofold - the transition temperature changes towards increasing the\ntwo-phase domain, and long-lived mesoscopic inhomogeneities emerge in the\nmacroscopically homogeneous domain. These homogeneities remain unchanged upon\napproach to the critical point of macroscopic phase separation and do not alter\nthe universal nature of criticality. However, a larger amount of cyclohexane\ngenerates additional liquid-liquid phase separation at lower temperatures.",
        "positive": "Holographic immunoassays: The size of a probe bead reported by holographic particle characterization\ndepends on the proportion of the surface area covered by bound target molecules\nand so can be used as an assay for molecular binding. We validate this\ntechnique by measuring the kinetics of irreversible binding for the antibodies\nimmunoglobulin G (IgG) and immunoglobulin M (IgM) as they attach to\nmicrometer-diameter colloidal beads coated with protein A. These measurements\nyield the antibodies' binding rates and can be inverted to obtain the\nconcentration of antibodies in solution. Holographic molecular binding assays\ntherefore can be used to perform fast quantitative immunoassays that are\ncomplementary to conventional serological tests."
    },
    {
        "anchor": "Metastability of Discrete-Symmetry Flocks: We study the stability of the ordered phase of flocking models with a scalar\norder parameter. Using both the active Ising model and a hydrodynamic\ndescription, we show that droplets of particles moving in the direction\nopposite to that of the ordered phase nucleate and grow. We characterize\nanalytically this self-similar growth and demonstrate that droplets spread\nballistically in all directions. Our results imply that, in the thermodynamic\nlimit, discrete-symmetry flocks -- and, by extension, continuous-symmetry\nflocks with rotational anisotropy -- are metastable in all dimensions.",
        "positive": "Evidence for compact cooperatively rearranging regions in a supercooled\n  liquid: We examine structural relaxation in a supercooled glass-forming liquid\nsimulated by NVE molecular dynamics. Time correlations of the total kinetic\nenergy fluctuations are used as a comprehensive measure of the system's\napproach to the ergodic equilibrium. We find that, under cooling, the total\nstructural relaxation becomes delayed as compared with the decay of the\ncomponent of the intermediate scattering function corresponding to the main\npeak of the structure factor. This observation can be explained by collective\nmovements of particles preserving many-body structural correlations within\ncompact 3D cooperatively rearranging regions."
    },
    {
        "anchor": "Swelling cholesteric liquid crystal shells to direct colloids at the\n  interface: Cholesteric liquid crystals can exhibit spatial patterns in molecular\nalignment at interfaces that can be exploited for particle assembly. These\npatterns emerge from the competition between bulk and surface energies, tunable\nwith the system geometry. In this work, we use the osmotic swelling of\ncholesteric double emulsions to assemble colloidal particles through a\npathway-dependent process. Particles can be repositioned from a\nsurface-mediated to an elasticity-mediated state through dynamically thinning\nthe cholesteric shell at a rate comparable to that of colloidal adsorption. By\ntuning the balance between surface and bulk energies with the system geometry,\ncolloidal assemblies on the cholesteric interface can be molded by the\nunderlying elastic field to form linear aggregates. The transition of adsorbed\nparticles from surface regions with homeotropic anchoring to defect regions is\naccompanied by a reduction in particle mobility. The arrested assemblies\nsubsequently map out and stabilize topological defects. These results\ndemonstrate the kinetic arrest of interfacial particles within definable\npatterns by regulating the energetic frustration within cholesterics. This work\nhighlights the importance of kinetic pathways for particle assembly in liquid\ncrystals, of relevance to optical and energy applications.",
        "positive": "The onset and dynamics of avalanches in a rotating cylinder: From\n  experimental data to a new geometric model: Particle image velocimetry has been applied to measure particle velocities on\nthe free surface of a bed of particles within a rotating cylinder during\navalanching. The particle velocities were used to examine the validity of\nexisting avalanche models and to propose an alternative model. The movement of\nparticles depends on their location on the surface of the bed: particles\nlocated near the center of the bed travel the farthest, while the distance\ntravelled decreases at an increasing rate for particles located farther from\nthe center. The start of an avalanche can be determined to a single initiation\npoint, that can also be located on the bottom half of the bed; the avalanche\nquickly propagates through the entire free surface, with 90% of the surface in\nmotion within 257 ms. The experimental insight is used to formulate a new\ngeometric model, in which three equal sized sections flow down the bed during\nan avalanche. The predictions of the model are confirmed by experimental mixing\nmeasurements."
    },
    {
        "anchor": "The vibrational density of states of a disordered gel model: We investigate the vibrational density of states (vDOS) in harmonic\napproximation of a binary mixture of colloidal patchy particles with two and\nthree patches for different relative compositions $x_2$. At low temperature,\nthis system forms a thermo-reversible gel, i.e. a fully bonded network of\nchains of two-patches particles, in which the branching points are provided by\nthree-patches particles. For all the compositions we find in the vDOS a\npronounced peak at low frequency whose height grows on increasing the fraction\nof two-functional particles, or equivalently with the average length of the\nchains. To identify the various spectral features, we compare the vDOS of the\nwhole system with the one of small representative structures of the network and\nwith the vDOS of a long linear chain of two-patches particles and we find that\nthese structures are indeed able to rationalize the various peaks in the vDOS\nof the full system. At large $x_2$ the vDOS of the gel and of the long chain\nshow remarkable similarities. Analyzing the dispersion relations and the\nspectrum of the linear chain we show that the excess of low frequency modes,\nthe analog of the boson peak in glassy disordered systems, arises from the\nstrong coupling between rotations and translations.",
        "positive": "Computing the Frequency-Dependent NMR Relaxation of $^1$H Nuclei in\n  Liquid Water: It is the purpose of this paper to present a computational framework for\nreliably determining the frequency-dependent intermolecular and intramolecular\nNMR dipole-dipole relaxation rate of spin $1/2$ nuclei from MD simulations. The\napproach avoids alterations caused by well-known finite-size effects of the\ntranslational diffusion. Moreover, a procedure is derived to control and\ncorrect for effects caused by fixed distance-sampling cutoffs and periodic\nboundary conditions. By construction, this approach is capable of accurately\npredicting the correct low-frequency scaling behavior of the intermolecular NMR\ndipole-dipole relaxation rate and thus allows the reliable calculation of the\nfrequency-dependent relaxation rate over many orders of magnitude. Our approach\nis based on the utilisation of the theory of Hwang and Freed for the\nintermolecular dipole-dipole correlation function and its corresponding\nspectral density [J. Chem. Phys. 63, 4017 (1975)] and its combination with data\nfrom molecular dynamics (MD) simulations. The deviations from the Hwang and\nFreed theory caused by periodic boundary conditions and sampling distance\ncutoffs are quantified by means of random walker Monte Carlo simulations. An\nexpression based on the Hwang and Freed theoryis also suggested for correcting\nthose effects. As a proof of principle, our approach is demonstrated by\ncomputing the frequency-dependent inter- and intramolecular dipolar NMR\nrelaxation rate of the $^1$H nuclei in liquid water at $273\\,\\mbox{K}$ and\n$298\\,\\mbox{K}$ based on simulations of the TIP4P/2005 model. Our calculations\nare suggesting that the intermolecular contribution to the $^1$H NMR relaxation\nrate of the TIP4P/2005 model in the extreme narrowing limit has previously been\nsubstantially underestimated."
    },
    {
        "anchor": "Resonant inelastic soft-x-ray scattering spectra at the N1s and C1s\n  edges of poly(pyridine-2,5-diyl): Resonant inelastic scattering measurements of poly(pyridine-2,5-diyl) have\nbeen performed at the N1s and C1s edges using synchrotron radiation. For\ncomparison, molecular orbital calculations of the spectra have been carried out\nwith the repeat unit as a model molecule of the polymer chain. The resonant\nemission spectra show depletion of the p electron bands which is consistent\nwith symmetry selection and momentum conservation rules. The depletion is most\nobvious in the resonant inelastic scattering spectra of carbon while the\nnitrogen spectra are dominated by lone pair n orbital emission of s symmetry\nand are less excitation energy dependent. By comparing the measurements to\ncalculations an isomeric dependence of the resonant spectra is found giving\npreference to two of the four possible isomers in the polymer.",
        "positive": "Mean-field model for the Curie-Weiss temperature dependence of coherence\n  length in metallic liquids: The coherence length of the medium-range order (MRO) in metallic liquids is\nknown to display a Curie-Weiss temperature dependence; its inverse is linearly\nrelated to temperature, and when extrapolated from temperatures above the glass\ntransition, the coherence length diverges at a negative temperature with a\ncritical exponent of unity. We propose a mean-field pseudospin model that\nexplains this behavior. Specifically, we model the atoms and their local\nenvironment as Ising spins with antiferromagnetic exchange interactions. We\nfurther superimpose an exchange interaction between dynamical heterogeneities,\nor clusters of atoms undergoing cooperative motion. The coherence length in the\nmetallic liquid is thus the correlation length between dynamical\nheterogeneities. Our results reaffirm the idea that the MRO coherence length is\na measure of point-to-set correlations, and that local frustrations in the\ninteratomic interactions are prominent in metallic liquids."
    },
    {
        "anchor": "Granular Solid Hydrodynamics: Dense Flow, Fluidization and Jamming: Granular solid hydrodynamics, constructed to describe quasi-elastic and\nplastic motion of granular solid, is shown also capable of accounting for the\nrheology of granular dense flow. This makes it a unified, though still\nqualitative, hydrodynamic description, enabling one to tackle fluidization and\njamming, the hysteretic transition between elasto-plastic motion and uniform\ndense flow.",
        "positive": "Monte Carlo simulations of a tethered membrane model on a disk with\n  intrinsic curvature: A first-order phase transition separating the smooth phase from the crumpled\none is found in a fixed connectivity surface model defined on a disk. The\nHamiltonian contains the Gaussian term and an intrinsic curvature term."
    },
    {
        "anchor": "A Classical Density-Functional Theory for Describing Water Interfaces: We develop a classical density functional for water which combines the White\nBear fundamental-measure theory (FMT) functional for the hard sphere fluid with\nattractive interactions based on the Statistical Associating Fluid Theory\n(SAFT-VR). This functional reproduces the properties of water at both long and\nshort length scales over a wide range of temperatures, and is computationally\nefficient, comparable to the cost of FMT itself. We demonstrate our functional\nby applying it to systems composed of two hard rods, four hard rods arranged in\na square and hard spheres in water.",
        "positive": "On the friction coefficient of straight-chain aggregates: A methodology to calculate the friction coefficient of an aggregate in the\ncontinuum regime is proposed. The friction coefficient and the monomer\nshielding factors, aggregate-average or individual, are related to the\nmolecule-aggregate collision rate that is obtained from the molecular diffusion\nequation with an absorbing boundary condition on the aggregate surface.\nCalculated friction coefficients of straight chains are in very good agreement\nwith previous results, suggesting that the friction coefficients may be\naccurately calculated from the product of the collision rate and an average\nmomentum transfer,the latter being independent of aggregate morphology.\nLangevin-dynamics simulations show that the diffusive motion of straight-chain\naggregates may be described either by a monomer-dependent or an\naggregate-average random force, if the shielding factors are appropriately\nchosen."
    },
    {
        "anchor": "Randomness in self-assembled colloidal crystals can widen photonic band\n  gaps through particle shape and internal structure: Using computer simulations, we explore how thermal noise-induced randomness\nin a self-assembled photonic crystal affects its photonic band gaps (PBGs). We\nconsider a two-dimensional photonic crystal comprised of a self-assembled array\nof parallel dielectric hard rods of infinite length with circular or square\ncross section. We find the PBGs can exist over a large range of intermediate\npacking densities. Counterintuitively, the largest band gap does not always\nappear at the packing density where the crystal is most ordered, despite the\nrandomness inherent in any self-assembled structure. For rods with square cross\nsection at intermediate packing densities, we find that the transverse magnetic\n(TM) band gap of the self-assembled (i.e. thermal) system can be larger than\nthat of identical rods arranged in a perfect square lattice. By considering\nhollow rods, we find the band gap of transverse electric (TE) modes can be\nsubstantially increased while that of TM modes show no obvious improvement over\nsolid rods. Our study suggests that particle shape and internal structure can\nbe used to engineer the PBG of a self-assembled system despite the positional\nand orientational randomness arising from thermal noise.",
        "positive": "Tailoring collective motion of kinesin-driven microtubules via\n  topographic landscapes: Biomolecular motor proteins that generate forces by consuming chemical energy\nobtained from ATP hydrolysis are pivotal for organizing broad cytoskeletal\nstructures in living cells. The control of such cytoskeletal structures\nbenefits programmable protein patterning; however, our current knowledge is\nlimited owing to the underdevelopment of an engineering approach for\ncontrolling pattern formation. Here, we demonstrate the tailoring of assembled\npatterns of microtubules (MTs) driven by kinesin motors by designing the\nboundary shape in fabricated microwells. We found an MT bundle structure along\nthe microwell wall and a bridging structure perpendicular to the wall.\nCorroborated by the theory of self-propelled rods, we further showed that the\nalignment of MTs defined by the boundary shape determined the transition of the\nassembled patterns, providing a blueprint to reconstruct bridge structures in\nmicrochannels. Our findings provide a geometric rule to tailor the\nself-organization of cytoskeletons and motor proteins for nanotechnological\napplications."
    },
    {
        "anchor": "Disordered collective motion in dense assemblies of persistent particles: We explore the emergence of nonequilibrium collective motion in disordered\nnon-thermal active matter when persistent motion and crowding effects compete,\nusing simulations of a two-dimensional model of size polydisperse\nself-propelled particles. In stark contrast with monodisperse systems, we find\nthat polydispersity stabilizes a homogeneous active liquid at arbitrary large\npersistence times, characterized by remarkable velocity correlations and\nirregular turbulent flows. For all persistence values, the active fluid\nundergoes a nonequilibrium glass transition at large density. This is\naccompanied by collective motion, whose nature evolves from near-equilibrium\nspatially heterogeneous dynamics at small persistence, to a qualitatively\ndifferent intermittent dynamics when persistence is large. This latter regime\ninvolves a complex time evolution of the correlated displacement field",
        "positive": "Origin of two distinct stress relaxation regimes in shear jammed dense\n  suspensions: Many dense particulate suspensions show a stress induced transformation from\na liquid-like state to a solid-like shear jammed (SJ) state. However, the\nunderlying particle-scale dynamics leading to such striking, reversible\ntransition of the bulk remains unknown. Here, we study transient stress\nrelaxation behaviour of SJ states formed by a well-characterized dense\nsuspension under a step strain perturbation. We observe a strongly\nnon-exponential relaxation that develops a sharp discontinuous stress drop at\nshort time for high enough peak-stress values. High resolution boundary imaging\nand normal stress measurements confirm that such stress discontinuity\noriginates from the localized plastic events, whereas, system spanning dilation\ncontrols the slower relaxation process. We also find an intriguing correlation\nbetween the nature of transient relaxation and the steady state shear jamming\nphase diagram obtained from the Wyart-Cates Model."
    },
    {
        "anchor": "Beating of grafted chains induced by active Brownian particles: We study the interplay between active Brownian particles (ABPs) and a hairy\nsurface in two dimensional geometry. We find that the increase of propelling\nforce leads to and enhances inhomogeneous accumulation of ABPs inside the brush\nregion. Oscillation of chain bundles (beating like cilia) is found in company\nwith the formation and disassembly of dynamic cluster of ABPs at large\npropelling forces. Meanwhile chains are stretched and pushed down due to the\neffective shear force by ABPs. The decrease of the average brush thickness with\npropelling force reflects the growth of the beating amplitude of chain bundles.\nFurthermore, the beating phenomenon is investigated in a simple single-chain\nsystem. We find that the chain swings regularly with a major oscillatory\nperiod, which increases with chain length and decreases with the increase of\npropelling force. We build a theory to describe the phenomenon and the\npredictions on the relationship between period and amplitude for various chain\nlengths and propelling forces agree very well with simulation data.",
        "positive": "Depletion interaction effects on the tunneling conductivity of nanorod\n  suspensions: We study by simulation and theory how the addition of insulating spherical\nparticles affects the conductivity of fluids of conducting rods, modeled by\nspherocylinders. The electrical connections are implemented as tunneling\nprocesses, leading to a more detailed and realistic description than a\ndiscontinuous percolation approach. We find that the spheres enhance the\ntunneling conductivity for a given concentration of rods and that the\nenhancement increases with rod concentration into the regime where the\nconducting network is well established. By reformulating the network of rods\nusing a critical path analysis, we quantify the effect of depletion-induced\nattraction between the rods due to the spheres. Furthermore, we show that our\nconductivity data are quantitatively reproduced by an effective medium\napproximation, which explicitly relates the system tunneling conductance to the\nstructure of the rod-sphere fluid."
    },
    {
        "anchor": "Crystal Growth Rates from Molecular Liquids: The Kinetics of Entropy\n  Loss: It has been established empirically that the rate of addition of molecules to\nthe crystal during crystal growth from the melt is proportional to\nexp(-|{\\Delta}S_fus|/R) where {\\Delta}S_fus is the entropy of fusion. Here we\nshow that this entropic slowdown arises directly from the separation of the\nentropy loss and energy loss processes associated with the freezing of the\nliquid. We present a theoretical treatment of the kinetics based on a model\nflat energy landscape and derive an explicit expression for the coupling\nmagnitude in terms of the crystal-melt interfacial free energy. The\nimplications of our work for nucleation kinetics are also discussed.",
        "positive": "Bubble propagation in a helicoidal molecular chain: We study the propagation of very large amplitude localized excitations in a\nmodel of DNA that takes explicitly into account the helicoidal structure. These\nexcitations represent the ``transcription bubble'', where the hydrogen bonds\nbetween complementary bases are disrupted, allowing access to the genetic code.\nWe propose these kind of excitations in alternative to kinks and breathers. The\nmodel has been introduced by Barbi et al. [Phys. Lett. A 253, 358 (1999)], and\nup to now it has been used to study on the one hand low amplitude breather\nsolutions, and on the other hand the DNA melting transition. We extend the\nmodel to include the case of heterogeneous chains, in order to get closer to a\ndescription of real DNA; in fact, the Morse potential representing the\ninteraction between complementary bases has two possible depths, one for A-T\nand one for G-C base pairs. We first compute the equilibrium configurations of\na chain with a degree of uncoiling, and we find that a static bubble is among\nthem; then we show, by molecular dynamics simulations, that these bubbles, once\ngenerated, can move along the chain. We find that also in the most unfavourable\ncase, that of a heterogeneous DNA in the presence of thermal noise, the\nexcitation can travel for well more 1000 base pairs."
    },
    {
        "anchor": "New insight into kinetics behavor of the structural formation process in\n  Agar gelation: A time-resolved experimental study on the kinetics and relaxation of the\nstructural formation process in gelling Agar-water solutions was carried out\nusing our custom-built torsion resonator. The study was based on measurements\nof three naturally cooled solutions with agar concentrations of 0.75%, 1.0% and\n2.0% w/w. It was found that the natural-cooling agar gelation process could be\ndivided into three stages, sol stage (Stage I), gelation zone (Stage II) and\ngel stage (Stage III), based on the time/temperature evolutions of the\nstructural development rate (SDR). An interesting fluctuant decaying behavior\nof SDR was observed in Stage II and III, indicative of a sum of multiple\nrelaxation processes and well described by a multiple-order Gaussisn-like\nequation: . More interestingly, the temperature dependences of the fitted\nvalues of Wn in Stage II and Stage III were found to follow the different\nArrhenius laws, with different activation energies of EaII= 39-74 KJ/mol and\nEaIII~7.0 KJ/mol. The two different Arrhenius-like behaviors respectively\nsuggest that dispersions in Stage II be attributed to the relaxation of the\nself-assembly of agar molecules or the growth of junction zones en route to\ngelation, in which the formation or fission of hydrogen bonding interactions\nplays an important role; and that dispersions in Stage III be attributed to the\nrelaxation dynamics of water released from various size domains close to the\ndomain of the viscous flow of water during the syneresis process.",
        "positive": "Constructing Custom Thermodynamics Using Deep Learning: One of the most exciting applications of artificial intelligence (AI) is\nautomated scientific discovery based on previously amassed data, coupled with\nrestrictions provided by known physical principles, including symmetries and\nconservation laws. Such automated hypothesis creation and verification can\nassist scientists in studying complex phenomena, where traditional physical\nintuition may fail. Here we develop a platform based on a generalized Onsager\nprinciple to learn macroscopic dynamical descriptions of arbitrary stochastic\ndissipative systems directly from observations of their microscopic\ntrajectories. Our method simultaneously constructs reduced thermodynamic\ncoordinates and interprets the dynamics on these coordinates. We demonstrate\nits effectiveness by studying theoretically and validating experimentally the\nstretching of long polymer chains in an externally applied field. Specifically,\nwe learn three interpretable thermodynamic coordinates and build a dynamical\nlandscape of polymer stretching, including the identification of stable and\ntransition states and the control of the stretching rate. Our general\nmethodology can be used to address a wide range of scientific and technological\napplications."
    },
    {
        "anchor": "Structure and thermodynamics in the linear modified Poisson-Boltzmann\n  theories in restricted primitive model electrolytes: Structure and thermodynamics in restricted primitive model electrolytes are\nexamined using three recently developed versions of a linear form of the\nmodified Poisson-Boltzmann equation. Analytical expressions for the osmotic\ncoefficient and the electrical part of the mean activity coefficient are\nobtained and the results for the osmotic and the mean activity coefficients are\ncompared with that from the more established mean spherical approximation,\nsymmetric Poisson-Boltzmann, modified Poisson-Boltzmann theories, and available\nMonte Carlo simulation results. The linear theories predict the thermodynamics\nto a remarkable degree of accuracy relative to the simulations and are\nconsistent with the mean spherical approximation and modified Poisson-Boltzmann\nresults. The predicted structure in the form of the radial distribution\nfunctions and the mean electrostatic potential also compare well with the\ncorresponding results from the formal theories. The excess internal energy and\nthe electrical part of the mean activity coefficient are shown to be identical\nanalytically for the mean spherical approximation and the linear modified\nPoisson-Boltzmann theories.",
        "positive": "Towards a 'Thermodynamics' of Active Matter: Self-propulsion allows living systems to display unusual collective behavior.\nUnlike passive systems in thermal equilibrium, active matter systems are not\nconstrained by conventional thermodynamic laws. A question arises however as to\nwhat extent, if any, can concepts from classical thermodynamics be applied to\nnonequilibrium systems like active matter. Here we use the new swim pressure\nperspective to develop a simple theory for predicting phase separation in\nactive matter. Using purely mechanical arguments we generate a phase diagram\nwith a spinodal and critical point, and define a nonequilibrium chemical\npotential to interpret the \"binodal.\" We provide a generalization of\nthermodynamic concepts like the free energy and temperature for nonequilibrium\nactive systems. Our theory agrees with existing simulation data both\nqualitatively and quantitatively and may provide a framework for understanding\nand predicting the behavior of nonequilibrium active systems."
    },
    {
        "anchor": "Influence of material stretchability on the equilibrium shape of a\n  M\u00f6bius band: We use a discrete, lattice-based model for two-dimensional materials to show\nthat M\\\"obius bands made with stretchable materials are less likely to crease\nor tear. This stems a delocalization of twisting strain that occurs if\nstretching is allowed. The associated low-energy configurations provide\nstrategic target shapes for the guided assembly of nanometer and micron scale\nM\\\"obius bands. To predict macroscopic band shapes for a given material, we\nestablish a connection between stretchability and relevant continuum moduli,\nleading to insight regarding the practical feasibility of synthesizing M\\\"obius\nbands from materials with continuum parameters that can be measured\nexperimentally or estimated by upscale averaging. To take advantage of\nstretchability in the case of M\\\"obius bands made of graphene, DNA, and other\neffectively unstretchable materials, we develop and explore a novel\narchitecture that uses the Chinese finger trap as a fundamental building block\nand imparts notable stretchability to otherwise unstretchable materials.",
        "positive": "Effective viscosity of methyl cellulose solutions in phosphate buffered\n  saline in real-time deformability cytometry: Here, we derive the equations to calculate the effective viscosity of\nsolutions of methyl cellulose (MC) dissolved in phosphate buffered saline (PBS)\nin real-time deformability cytometry (RT-DC) experiments. The calculations are\nbased on the rheometer measurements described by B\\\"uy\\\"ukurganci et al.\n(2022). We outline how to get the final equations and compare the results to\nthe current viscosity model from Herold (2017). These viscosity functions will\nbe used to determine the Young's moduli of biological cells and other soft\nmaterials from RT-DC experiments."
    },
    {
        "anchor": "Composition variation and underdamped mechanics near membrane proteins\n  and coats: We study the effect of membrane proteins on the shape, composition and\nthermodynamic stability of the surrounding membrane. When the coupling between\nmembrane composition and curvature is strong enough the nearby composition and\nshape both undergo a transition from over-damped to under-damped spatial\nvariation, well before the membrane becomes unstable in the bulk. This\ntransition is associated with a change in the sign of the thermodynamic energy\nand hence has the unusual features that it can favour the early stages of coat\nassembly necessary for vesiculation (budding), while suppressing the activity\nof mechanosensitive membrane channels and transporters. Our results also\nsuggest an approach to obtain physical parameters that are otherwise difficult\nto measure.",
        "positive": "Stripe formation in horizontally oscillating granular suspensions: We present the results of an experimental study of pattern formation in\nhorizontally oscillating granular suspensions. Starting from a homogeneous\nstate, the suspension turns into a striped pattern within a specific range of\nfrequencies and amplitudes of oscillation. We observe an initial development of\nlayered structures perpendicular to the vibration direction and a gradual\ncoarsening of the stripes. However, both processes gradually slow down and\neventually saturate. The probability distribution of the stripe width\napproaches a nonmonotonic steady-state form which can be approximated by a\nPoisson distribution. We observe similar structures in MD simulations of soft\nspherical particles coupled to the motion of the surrounding fluid."
    },
    {
        "anchor": "The Wigner Strong-Coupling approach: Mini-review on strong coupling approaches in charged soft matter, with\nemphasis on Wigner technique.",
        "positive": "Evolution of network architecture in a granular material under\n  compression: As a granular material is compressed, the particles and forces within the\nsystem arrange to form complex heterogeneous structures. Force chains are a\nprime example and are thought to constrain bulk properties such as mechanical\nstability and acoustic transmission. However, characterizing the dynamic nature\nof mesoscale architectures in granular systems can be challenging. A growing\nbody of work has shown that graph theoretic approaches may provide a useful\nfoundation for tackling these problems. Here, we extend current approaches by\nutilizing multilayer networks as a framework for directly quantifying the\nevolution of mesoscale architecture in a compressed granular system. We examine\na quasi-two-dimensional aggregate of photoelastic disks, subject to biaxial\ncompression through a series of small, quasistatic steps. Treating particles as\nnetwork nodes and inter-particle forces as network edges, we construct a\nmultilayer network by linking together the series of static force networks that\nexist at each strain step. We then extract the inherent mesoscale structure\nfrom the system by using a generalization of community detection methods, and\nwe define quantitative measures to characterize the reconfiguration and\nevolution of this structure throughout compression. By separately considering\nthe network of normal and tangential forces, we find that they display\ndifferent structural evolution. To test the sensitivity of the network model to\nparticle properties, we examine whether the method can distinguish a subsystem\nof low-friction particles within a bath of higher-friction particles. We find\nthat this can be done by considering the network of tangential forces. The\nresults discussed throughout this study suggest that these novel network\nscience techniques may provide a direct way to compare and classify data from\nsystems under different external conditions or with different physical makeup."
    },
    {
        "anchor": "Optimal Control of Active Nematics: In this work we present the first systematic framework to sculpt active\nnematics systems, using optimal control theory and a hydrodynamic model of\nactive nematics. We demonstrate the use of two different control fields, (1)\napplied vorticity and (2) activity strength, to shape the dynamics of an\nextensile active nematic that is confined to a disk. In the absence of control\ninputs, the system exhibits two attractors, clockwise and counterclockwise\ncirculating states characterized by two co-rotating topological $+\\frac{1}{2}$\ndefects. We specifically seek spatiotemporal inputs that switch the system from\none attractor to the other; we also examine phase-shifting perturbations. We\nidentify control inputs by optimizing a penalty functional with three\ncontributions: total control effort, spatial gradients in the control, and\ndeviations from the desired trajectory. This work demonstrates that optimal\ncontrol theory can be used to calculate non-trivial inputs capable of\nrestructuring active nematics in a manner that is economical, smooth, and\nrapid, and therefore will serve as a guide to experimental efforts to control\nactive matter.",
        "positive": "New Phase Transition in Polymer Solutions with Multicomponent Solvent: Considering the density-density correlation function of a concentrated\npolymer solution with multicomponent solvent we find a phase transition due to\nthe heterogeneity of excluded volume constant. This new phase transition\nimplies a strong enhancement of the scattered light intensity in the critical\nregion, which can explain a recent experiment showing strong light scattering\nfrom a ternary polymer system consisting of polyethylene oxide (PEO) dissolved\nin nitroethane and 3methyl-pentane."
    },
    {
        "anchor": "Microscopic origin of nonlinear non-affine deformation and stress\n  overshoot in bulk metallic glasses: The atomic theory of elasticity of amorphous solids, based on the nonaffine\nresponse formalism, is extended into the nonlinear stress-strain regime by\ncoupling with the underlying irreversible many-body dynamics. The latter is\nimplemented in compact analytical form using a qualitative method for the\nmany-body Smoluchowski equation. The resulting nonlinear stress-strain\n(constitutive) relation is very simple, with few fitting parameters, yet\ncontains all the microscopic physics. The theory is successfully tested against\nexperimental data on metallic glasses, and it is able to reproduce the\nubiquitous feature of stress-strain overshoot upon varying temperature and\nshear rate. A clear atomic-level interpretation is provided for the stress\novershoot, in terms of the competition between the elastic instability caused\nby nonaffine deformation of the glassy cage and the stress buildup due to\nviscous dissipation.",
        "positive": "Vibrational modes identify soft spots in a sheared disordered packing: We analyze low-frequency vibrational modes in a two-dimensional,\nzero-temperature, quasistatically sheared model glass to identify a population\nof structural \"soft spots\" where particle rearrangements are initiated. The\npopulation of spots evolves slowly compared to the interval between particle\nrearrangements and the soft spots are structurally different from the rest of\nthe system. Our results suggest that disordered solids flow via localized\nrearrangements that tend to occur at soft spots, which are analogous to\ndislocations in crystalline solids."
    },
    {
        "anchor": "Fractional Brownian motion approach to polymer translocation: the\n  governing equation of motion: We suggest a governing equation which describes the process of polymer chain\ntranslocation through a narrow pore and reconciles the seemingly contradictory\nfeatures of such dynamics: (i) a Gaussian probability distribution of the\ntranslocated number of polymer segments at time $t$ after the process has\nbegun, and (ii) a sub-diffusive increase of the distribution variance $\\Delta\n(t)$ with elapsed time, $\\Delta(t) \\propto t^{\\alpha}$. The latter quantity\nmeasures the mean-squared number $s$ of polymer segments which have passed\nthrough the pore, $\\Delta(t) = <[s(t)-s(t=0)]^2>$, and is known to grow with an\nanomalous diffusion exponent $\\alpha < 1$.\n  Our main assumption - a Gaussian distribution of the translocation velocity\n$v(t)$ - and some important theoretical results, derived recently, are shown to\nbe supported by extensive Brownian dynamics simulation which we performed in\n$3D$. We also numerically confirm the predictions made in ref.\\cite{Kantor_3},\nthat the exponent $\\alpha$ changes from $0.91$ to $0.55$, to $0.91$, for short,\nintermediate and long time regimes, respectively.",
        "positive": "Role of local assembly in the hierarchical crystallization of\n  associating colloidal hard hemispheres: Hierarchical self-assembly consisting of local associations of simple\nbuilding-blocks for the formation of complex structures widely exists in\nnature, while the essential role of local assembly remains unknown. In this\nwork, by using computer simulations, we study a simple model system consisting\nof associating colloidal hemispheres crystallizing into face-centered-cubic\ncrystals comprised of spherical dimers of hemispheres, focusing on the effect\nof dimer formation on the hierarchical crystallization. We found that besides\nassisting the crystal nucleation because of increasing the symmetry of\nbuilding-blocks, the association between hemispheres can also induce both\nre-entrant melting and re-entrant crystallization depending on the range of\ninteraction. Especially when the interaction is highly sticky, we observe a\nnovel re-entrant crystallization of identical crystals, which melt only in\ncertain temperature range. This offers a new axis in fabricating responsive\ncrystalline materials by tuning the fluctuation of local association."
    },
    {
        "anchor": "Nanostructure of edge dislocations in a smectic C* liquid crystal: We report on the first direct nanoscale imaging of elementary edge\ndislocations in a thermotropic chiral smectic C liquid crystal with the Burgers\nvector equal to one smectic layer spacing d. We find two different types of\ndislocation profiles. In the dislocation of type A, the layers deformations\nlack mirror symmetry with respect to the plane perpendicular to the Burgers\nvector; the dislocation core size is on the order of d. In the dislocation of\ntype S, the core is strongly anisotropic, extending along the Burgers vector\nover distances much larger (by a factor of 4) than d. The difference is\nattributed to a different orientation of the molecular tilt plane with respect\nto the dislocation axis; the asymmetric layers distortions are observed when\nthe molecular tilt plane is perpendicular to the axis and the split S core is\nobserved when the molecules are tilted along the line.",
        "positive": "Common anesthetic molecules prefer to partition in liquid disorder phase\n  domain in a composite multicomponent membrane: Despite a vast clinical application of anesthetics, the molecular level of\nunderstanding of general anesthesia is far from our reach. Using atomistic\nmolecular dynamics simulation, we study the effects of common anesthetics:\nethanol, chloroform and methanol in the fully hydrated symmetric multicomponent\nlipid bilayer membrane comprising of an unsaturated\npalmitoyl-oleoyl-phosphatidyl-choline (POPC), a saturated\npalmitoyl-sphingomyelin (PSM) and cholesterol (Chol) which exhibits phase\ncoexistence of liquid-ordered (lo) - liquid disordered (ld) phase domains. We\nfind that the mechanical and physical properties such as the thickness and\nrigidity of the membrane are reduced while the lateral expansion of the\nmembrane is exhibited in presence of anesthetic molecules. Our simulation shows\nboth lateral and transverse heterogeneity of the anesthetics in the composite\nmulticomponent lipid membrane. Both ethanol and chloroform partition in the\nPOPC-rich ld phase domain, while methanol is distributed in both lo-ld phase\ndomains. Chloroform can penetrate deep into the membrane, while methanol\npartitions mostly at the water layer closed to the head-group and ethanol at\nthe neck of the lipids in the membrane."
    },
    {
        "anchor": "Thermalization Calorimetry: A simple method for investigating glass\n  transition and crystallization of supercooled liquids: We present a simple method for fast and cheap thermal analysis on supercooled\nglass-forming liquids. This \"Thermalization Calorimetry\" technique is based on\nmonitoring the temperature and its rate of change during heating or cooling of\na sample for which the thermal power input comes from heat conduction through\nan insulating material, i.e., is proportional to the temperature difference\nbetween sample and surroundings. The monitored signal reflects the sample's\nspecific heat and is sensitive to exo- and endothermic processes. The technique\nis useful for studying supercooled liquids and their crystallization, e.g., for\nlocating the glass transition and melting point(s), as well as for\ninvestigating the stability against crystallization and estimating the relative\nchange in specific heat between the solid and liquid phases at the glass\ntransition.",
        "positive": "Phase separation in a two-dimensional binary colloidal mixture by quorum\n  sensing activity: We present results from Langevin dynamics simulations of a glassy\nactive-passive mixture of soft-repulsive binary colloidal disks. Activity on\nthe smaller particles is applied according to the quorum sensing scheme, in\nwhich a smaller particle will be active for a persistence time if its local\nnearest neighbors are equal to or greater than a certain threshold value. We\nstart with a passive glassy state of the system and apply activity to the\nsmaller particles, which shows a nonmonotonous glassy character of the active\nparticles with the persistence time of the active force, from its passive limit\n(zero activity). On the other hand, passive particles of the active-passive\nmixture phase separate at the intermediate persistence time of the active\nforce, resulting in the hexatic-liquid and solid-liquid phases. Thus, our\nsystem shows three regimes as active glass, phase separation, and active\nliquid, as the persistence time increases from its smaller values. We show that\nthe solidlike and hexatic phases consisting of passive large particles are\nstable due to the smaller momentum transfer from active to passive particles,\ncompared to the higher persistence time where the positional and orientational\nordering vanishes. Our model is relevant to active biological systems, where\nglassy dynamics is present, e.g., bacterial cytoplasm, biological tissues,\ndense quorum sensing bacteria, and synthetic smart amorphous glasses."
    },
    {
        "anchor": "Shock driven jamming and periodic fracture of particulate rafts: A tenuous monolayer of hydrophobic particles at the air-water interface often\nforms a scum or raft. When such a monolayer is disturbed by the localized\nintroduction of a surfactant droplet, a radially divergent surfactant shock\nfront emanates from the surfactant origin and packs the particles into a\njammed, compact, annular band with a packing fraction that saturates at a peak\npacking fraction $\\phi^*$. As the resulting two-dimensional, disordered elastic\nband grows with time and is driven radially outwards by the surfactant, it\nfractures to form periodic triangular cracks with robust geometrical features.\nWe find the number of cracks $N$ and the compaction band radius $R^*$ at\nfracture onset vary monotonically with the initial packing fraction\n($\\phi_{init}$). However, its width $W^*$ is constant for all $\\phi_{init}$. A\nsimple geometric theory that treats the compaction band as an elastic annulus,\nand accounts for mass conservation allows us to deduce that $N \\simeq 2\\pi\nR^*/W^* \\simeq 4\\pi \\phi_{RCP}/\\phi_{init}$, a result we verify both\nexperimentally and numerically. We show the essential ingredients for this\nphenomenon are an initially low enough particulate packing fraction that allows\nsurfactant driven advection to cause passive jamming and eventual fracture of\nthe hydrophobic particulate interface.",
        "positive": "Stabilizing Grafted Colloids in a Polymer Melt: Favorable Enthalpic\n  Interactions: The interactions between spherical colloids covered with end-grafted polymers\n(brushes) immersed in a polymer melt are studied theoretically. We show that\nattractive enthalpic interactions between the two polymer species,\ncharacterized by a negative Flory parameter (chi<0), can stabilize the\ncolloidal dispersion. The stabilizing mechanism is a result of a structural\nchange from a dry brush, where the melt chains do not penetrate deeply into the\nbrush, to a wet brush, where the free chains penetrate the brush and force the\ngrafted chains to extend into the melt."
    },
    {
        "anchor": "Extended sedimentation profiles in charged colloids: the gravitational\n  length, entropy, and electrostatics: We have measured equilibrium sedimentation profiles in a colloidal model\nsystem with confocal microscopy. By tuning the interactions, we have determined\nthe gravitational length in the limit of hard-sphere-like interactions, and\nusing the same particles, tested a recent theory [R.van Roij, J. Phys. Cond.\nMat. 15, S3569, (2003)], which predicts a significantly extended sedimentation\nprofile in the case of charged colloids with long-ranged repulsions, due to a\nspontaneously formed macroscopic electric field. For the hard-sphere-like\nsystem we find that the gravitational length matches that expected. By tuning\nthe buoyancy of the colloidal particles we have shown that a mean field\nhydrostatic equilibrium description even appears to hold in the case that the\ncolloid volume fraction changes significantly on the length scale of the\nparticle size. The extended sedimentation profiles of the colloids with\nlong-ranged repulsions are well-described by theory. Surprisingly, the theory\neven seems to hold at concentrations where interactions between the colloids,\nwhich are not modeled explicitly, play a considerable role.",
        "positive": "Mechanical properties of inclined frictional granular layers: We investigate the mechanical properties of inclined frictional granular\nlayers prepared with different protocols by means of DEM numerical simulations.\nWe perform an orthotropic elastic analysis of the stress response to a\nlocalized overload at the layer surface for several substrate tilt angles. The\ndistance to the unjamming transition is controlled by the tilt angle $\\alpha$\nwith respect to the critical angle $\\alpha_c$. We find that the shear modulus\nof the system decreases with $\\alpha$, but tends to a finite value as $\\alpha\n\\to \\alpha_c$. We also study the behaviour of various microscopic quantities\nwith $\\alpha$, and show in particular the evolution of the contact orientation\nwith respect to the orthotropic axes and that of the distribution of the\nfriction mobilisation at contact."
    },
    {
        "anchor": "Network disorder and nonaffine deformations in marginal solids: The most profound effect of disorder on the elastic response of solids is the\nnonaffinity of local displacements whereby the atoms (particles, network\njunctions) do not simply follow the macroscopic strain, as they do in perfect\ncrystals, but undergo additional displacements which result in a softening of\nresponse. Whether disorder can produce further effects has been an open and\ndifficult question due to our poor understanding of nonaffinity. Here we\npresent a systematic analysis of this problem by allowing both network disorder\nand lattice coordination to vary continuously under account of nonaffinity. In\none of its limits, our theory, supported by numerical simulations, shows that\nin lattices close to the limit of mechanical stability the elastic response\nstiffens proportionally to the degree of disorder. This result has important\nimplications in a variety of areas: from understanding the glass transition\nproblem to the mechanics of biological networks such as the cytoskeleton.",
        "positive": "Hydrodynamic Collective Effects of Active Protein Machines in Solution\n  and Lipid Bilayers: The cytoplasm and biomembranes in biological cells contain large numbers of\nproteins that cyclically change their shapes. They are molecular machines that\ncan function as molecular motors or carry out many other tasks in the cell. We\nanalyze the effects that hydrodynamic flows induced by active proteins have on\nother passive molecules in solution or membranes. We show that the diffusion\nconstants of passive particles are enhanced substantially. Furthermore, when\ngradients of active proteins are present, a chemotaxis-like drift of passive\nparticles takes place. In lipid bilayers, the effects are strongly nonlocal, so\nthat active inclusions in the membrane contribute to diffusion enhancement and\nthe drift. The results indicate that the transport properties of passive\nparticles in systems containing active proteins machines operating under\nnonequilibrium conditions differ from their counterparts in systems at thermal\nequilibrium."
    },
    {
        "anchor": "Bubble Assemblies in Ternary Systems with Long Range Interaction: A nonlocal diffuse interface model is used to study bubble assemblies in\nternary systems. As model parameters vary, a large number of morphological\nphases appear as stable stationary states. One open question related to the\npolarity direction of double bubble assemblies is answered numerically.\nMoreover, the average size of bubbles in a single bubble assembly depends on\nthe sum of the minority constituent areas and the long range interaction\ncoefficients. One identifies the ranges for area fractions and the long range\ninteraction coefficients for double bubble assemblies.",
        "positive": "Temperature-dependent mechanisms for the dynamics of protein-hydration\n  waters: a molecular dynamics simulation study: Molecular dynamics simulations are performed to study the\ntemperature-dependent dynamics and structures of the hydration shells of\nelastin-like and collagen-like peptides. For both model peptides, it is\nconsistently observed that, upon cooling, the mechanisms for water dynamics\ncontinuously change from small-step diffusive motion to large-step jump motion,\nthe temperature dependence of water dynamics shows a weak crossover from\nfragile behavior to strong behavior, and the order of the hydrogen-bond network\nincreases. The temperature of the weak crossover from fragile to strong\nbehavior is found to coincide with the temperature at which maximum possible\norder of the hydrogen-bond network is reached so that the structure becomes\ntemperature independent. In the strong regime, the temperature dependence of\nwater translation and rotational dynamics is characterized by an activation\nenergy of ca. E_a=0.43 eV, consistent with results from previous dielectric\nspectroscopy and nuclear magnetic resonance studies on protein hydration\nwaters. At these temperatures, a distorted pi-flip motion about the twofold\nmolecular symmetry axes, i.e., a water-specific beta process is an important\naspect of water dynamics, at least at the water-peptide interfaces. In\naddition, it is shown that the hydration waters exhibit pronounced dynamical\nheterogeneities, which can be traced back to a strong slowdown of water motion\nin the immediate vicinity of peptide molecules due to formation of\nwater-peptide hydrogen bonds."
    },
    {
        "anchor": "Dynamic stratification in drying films of colloidal mixtures: In simulations and experiments, we study the drying of films containing\nmixtures of large and small colloidal particles in water. During drying, the\nmixture stratifies into a layer of the larger particles at the bottom with a\nlayer of the smaller particles on top. We developed a model to show that a\ngradient in osmotic pressure, which develops dynamically during drying, is\nresponsible for the segregation mechanism behind stratification.",
        "positive": "Theory of sound propagation in superfluid-filled porous media: The theory of sound propagation in macroscopically isotropic and homogeneous\nporous media saturated with superfluid ^4He(so-called He II) has been developed\nneglecting all damping processes. The case when the normal fluid component is\nlocked inside a porous medium by viscous forces is investigated in detail. It\nis shown that in this case one shear wave and two longitudinal, fast and slow,\nwaves exist. Fast wave as well as slow wave is accompanied with temperature\noscillations. The velocities of these waves are obtained."
    },
    {
        "anchor": "Variational bounds and nonlinear stability of an active nematic\n  suspension: We use the entropy method to analyze the nonlinear dynamics and stability of\na continuum kinetic model of an active nematic suspension. From the time\nevolution of the relative entropy -- an energy-like quantity in the kinetic\nmodel -- we derive a variational bound on relative entropy fluctuations that\ncan be expressed in terms of orientational order parameters. From this bound we\nshow isotropic suspensions are nonlinearly stable for sufficiently low\nactivity, and derive upper bounds on spatiotemporal averages in the unstable\nregime that are consistent with fully nonlinear simulations. This work\nhighlights the self-organizing role of activity in particle suspensions, and\nplaces limits on how organized such systems can be.",
        "positive": "Instabilities, defects, and defect ordering in an overdamped active\n  nematic: We consider a phenomenological continuum theory for an extensile, overdamped\nactive nematic liquid crystal, applicable in the dense regime. Constructed from\ngeneral principles, the theory is universal, with parameters independent of any\nparticular microscopic realization. We show that it exhibits a bend instability\nsimilar to that seen in active suspensions, that leads to the proliferation of\ndefects. We find three distinct nonequilibrium steady states: a defect-ordered\nnematic in which $+\\frac{1}{2}$ disclinations develop polar ordering, an\nundulating nematic state with no defects, and a turbulent defective nematic. We\ncharacterize the phenomenology of these phases and identify the relationship of\nthis theoretical description to experimental realizations and other theoretical\nmodels of active nematics."
    },
    {
        "anchor": "Stability of nanoparticle laden aerosol liquid droplets: We develop a model for the thermodynamics and evaporation dynamics of aerosol\ndroplets of a liquid such as water, surrounded by the gas. When the temperature\nand the chemical potential (or equivalently the humidity) are such that the\nvapour phase is the thermodynamic equilibrium state, then of course droplets of\nthe pure liquid evaporate over a relatively short time. However, if the\ndroplets also contain nanoparticles or any other non-volatile solute, then the\ndroplets can become thermodynamically stable. We show that the equilibrium\ndroplet size depends strongly on the amount and solubility of the nanoparticles\nwithin, i.e. on the nature of the particle interactions with the liquid, and of\ncourse also on the vapour temperature and chemical potential. We develop a\nsimple thermodynamic model for such droplets and compare predictions with\nresults from a lattice density functional theory that takes as input the same\nparticle interaction properties, finding very good agreement. We also use\ndynamical density functional theory to study the evaporation/condensation\ndynamics of liquid from/to droplets as they equilibrate with the vapour,\nthereby demonstrating droplet stability.",
        "positive": "Strain-induced alignment in collagen gels: Collagen is the most abundant extracellular-network-forming protein in animal\nbiology and is important in both natural and artificial tissues, where it\nserves as a material of great mechanical versatility. This versatility arises\nfrom its almost unique ability to remodel under applied loads into anisotropic\nand inhomogeneous structures. To explore the origins of this property, we\ndevelop a set of analysis tools and a novel experimental setup that probes the\nmechanical response of fibrous networks in a geometry that mimics a typical\ndeformation profile imposed by cells in vivo. We observe strong fiber alignment\nand densification as a function of applied strain for both uncrosslinked and\ncrosslinked collagenous networks. This alignment is found to be irreversibly\nimprinted in uncrosslinked collagen networks, suggesting a simple mechanism for\ntissue organization at the microscale. However, crosslinked networks display\nsimilar fiber alignment and the same geometrical properties as uncrosslinked\ngels, but with full reversibility. Plasticity is therefore not required to\nalign fibers. On the contrary, our data show that this effect is part of the\nfundamental non-linear properties of fibrous biological networks."
    },
    {
        "anchor": "The relationship between induced fluid structure and boundary slip in\n  nanoscale polymer films: The molecular mechanism of slip at the interface between polymer melts and\nweakly attractive smooth surfaces is investigated using molecular dynamics\nsimulations. In agreement with our previous studies on slip flow of\nshear-thinning fluids, it is shown that the slip length passes through a local\nminimum at low shear rates and then increases rapidly at higher shear rates. We\nfound that at sufficiently high shear rates, the slip flow over atomically flat\ncrystalline surfaces is anisotropic. It is demonstrated numerically that the\nfriction coefficient at the liquid-solid interface (the ratio of viscosity and\nslip length) undergoes a transition from a constant value to the power-law\ndecay as a function of the slip velocity. The characteristic velocity of the\ntransition correlates well with the diffusion velocity of fluid monomers in the\nfirst fluid layer near the solid wall at equilibrium. We also show that in the\nlinear regime, the friction coefficient is well described by a function of a\nsingle variable, which is a product of the magnitude of surface-induced peak in\nthe structure factor and the contact density of the adjacent fluid layer. The\nuniversal relationship between the friction coefficient and induced fluid\nstructure holds for a number of material parameters of the interface: fluid\ndensity, chain length, wall-fluid interaction energy, wall density, lattice\ntype and orientation, thermal or solid walls.",
        "positive": "The effects of forcing and dissipation on phase transitions in thin\n  granular layers: Recent experimental and computational studies of vibrated thin layers of\nidentical spheres have shown transitions to ordered phases similar to those\nseen in equilibrium systems. Motivated by these results, we carry out\nsimulations of hard inelastic spheres forced by homogenous white noise. We find\na transition to an ordered state of the same symmetry as that seen in the\nexperiments, but the clear phase separation observed in the vibrated system is\nabsent. Simulations of purely elastic spheres also show no evidence for phase\nseparation. We show that the energy injection in the vibrated system is\ndramatically different in the different phases, and suggest that this creates\nan effective surface tension not present in the equilibrium or randomly forced\nsystems. We do find, however, that inelasticity suppresses the onset of the\nordered phase with random forcing, as is observed in the vibrating system, and\nthat the amount of the suppression is proportional to the degree of\ninelasticity. The suppression depends on the details of the energy injection\nmechanism, but is completely eliminated when inelastic collisions are replaced\nby uniform system-wide energy dissipation."
    },
    {
        "anchor": "Effects of inhomogeneous partial absorption and the geometry of the\n  boundary on the population evolution of molecules diffusing in general porous\n  media: We consider aspects of the population dynamics, inside a bound domain, of\ndiffusing agents carrying an attribute which is stochastically destroyed upon\ncontact with the boundary. The normal mode analysis of the relevant Helmholtz\nequation under the partially absorbing, but uniform, boundary condition\nprovides a starting framework in understanding detailed evolution dynamics of\nthe attribute in the time domain. In particular, the boundary-localized\ndepletion has been widely employed in practical applications that depend on\ngeometry of various porous media such as rocks, cement, bones, and cheese.\nWhile direct relationship between the pore geometry and the\ndiffusion-relaxation spectrum forms the basis for such applications and has\nbeen extensively studied, relatively less attention has been paid to the\nspatial variation of the boundary condition. In this work, we focus on the way\nthe pore geometry and the inhomogeneous depletion strength of the boundary\nbecome intertwined and thus obscure the direct relationship between the\nspectrum and the geometry. It is often impossible to gauge experimentally the\ndegree to which such interference occur. We fill this gap by perturbatively\nincorporating classes of spatially-varying boundary conditions and derive their\nconsequences that are observable through numerical simulations or controlled\nexperiments on glass bead packs and artificially fabricated porous media. We\nidentify features of the spectrum that are most sensitive to the inhomogeneity\nand apply the method to the spherical pore with a simple hemi-spherical binary\ndistribution of the depletion strength and obtain bounds for the induced change\nin the slowest relaxation mode.",
        "positive": "Scattering of solitary waves in granular media: A detailed numerical study of the scattering of solitary waves by a barrier,\nin a granular media with Hertzian contact, shows the existence of secondary\nmultipulse structures generated at the interface of two \"sonic vacua\", which\nhave a similar structure as the one previously found by Nesterenko and\ncoworkers."
    },
    {
        "anchor": "The glass transition in molecules, colloids and grains: universality and\n  specificity: We highlight certain key achievements in experimental work on molecular,\ncolloidal and granular glassformers. This short review considers these three\nclasses of experimental systems and focusses largely on the work of the authors\nand their coworkers and thus is far from exhaustive. Our goal is rather to\ndiscuss particular experimental results from these classes and to explore\nuniversality and specificity across the broad range of length- and time-scales\nthey span. We emphasize that a variety of phenomena, not least dynamical\nheterogeneity, growing lengthscales and a change in structure, albeit subtle,\nare now well established in these three classes of glassformer. We then review\nsome experimental measurements which depend more specifically on the class of\nglassformer, such as the Gardner transition and some which have been\ninvestigated more in one or two classes than in all, such as configurational\nentropy and evidence for a dynamical phase transition. We finally put forward\nsome open questions and consider what could be done to fill some of the gaps\nbetween theoretical approaches and experiments.",
        "positive": "Pore emptying transition during nucleation in hydrophobic nanopores: Using the 2D Ising model we study the generic properties of nucleation in\nhydrophobic nanopores. To explore the pathways to nucleation of a spin-up phase\nfrom a metastable spin-down phase we perform umbrella sampling and transition\npath sampling simulations. We find that for narrow pores the nucleation occurs\non the surface outside the pore. For wide pores the nucleation starts in the\npore, and continues outside the filled pore. Intriguingly, we observe a pore\nemptying transition for a range of intermediate pore widths: a pre-critical\nnucleus fills the pore, continues to expand outside of the filled pore, but\nthen suddenly gets expelled from the pore before reaching its critical size."
    },
    {
        "anchor": "Probing the micromechanics of a multi-contact interface at the onset of\n  frictional sliding: Digital Image Correlation is used to study the micromechanics of a\nmulti-contact interface formed between a rough elastomer and a smooth glass\nsurface. The in-plane elastomer deformation is monitored during the incipient\nsliding regime, i.e. the transition between static and sliding contact. As the\nshear load is increased, an annular slip region, in coexistence with a central\nstick region, is found to progressively invade the contact. From the\ninterfacial displacement field, the tangential stress field can be further\ncomputed using a numerical inversion procedure. These local mechanical\nmeasurements are found to be correctly captured by Cattaneo and Mindlin (CM)'s\nmodel. However, close comparison reveals significant discrepancies in both the\ndisplacements and stress fields that reflect the oversimplifying hypothesis\nunderlying CM's scenario. In particular, our optical measurements allow us to\nexhibit an elasto-plastic like friction constitutive equation that differs from\nthe rigid-plastic behavior assumed in CM's model. This local constitutive law,\nwhich involves a roughness-related length scale, is consistent with the model\nof Bureau \\textit{et al.} [Proc. R. Soc. London A \\textbf{459}, 2787 (2003)]\nderived for homogeneously loaded macroscopic multi-contact interfaces, thus\nextending its validity to mesoscopic scales.measurements allow for the first\nquantitative test of Cattaneo and Mindlin (CM) classical model of the incipient\nsliding of a smooth interface. Small deviations are observed and interpreted as\na result of the finite compliance of the rough interface, a behavior which\ncontrasts with Amontons' law of friction assumed to be valid locally in CM's\nmodel. We illustrate how these measurements actually provide a method for\nprobing the rheology of the rough interface, which we find to be of the\nelasto-plastic type.",
        "positive": "The Range of Validity for the Kelvin Force: In a recent Letter, Luo, Du and Huang reported a novel convective instability\ndriven by a force rarely studied before -- that exerted by an external magnetic\nfield on a strongly magnetizable liquid. The associated physics is surprisingly\nrich and promises many more interesting results for the future. Unfortunately,\nthe analysis starts from a misconception and employs the Kelvin force outside\nits range of validity. Since few would recognize this as a mistake, and since\nits consequence in the given experiment is particularly direct and critical,\nthis is a point well worth being clarified, and clearly understood."
    },
    {
        "anchor": "The most energetically favorable configurations of hematite cube chains: Hematite at room temperature is a weak ferromagnetic material. Its permanent\nmagnetization is three orders smaller than for magnetite. Thus, hematite\ncolloids allow us to explore a different physical range of particle interaction\nparameters compared to ordinary ferromagnetic particle colloids. In this paper\nwe investigate a colloid consisting of hematite particles with cubic shape. We\nsearch for energetically favorable structures in an external magnetic field\nwith analytical and numerical methods and molecular dynamics simulations and\nanalyze whether it is possible to observe them in experiments. We find that\nenergetically favorable configurations are observable only for short chains.\nLonger chains usually contain kinks which are formed in the process of chain\nformation due to the interplay of energy and thermal fluctuations as an\nindividual cube can be in one of two alignments with an equal probability.",
        "positive": "Equilibration of Concentrated Hard Sphere Fluids: We report a systematic molecular dynamics study of the isochoric\nequilibration of hard-sphere fluids in their metastable regime close to the\nglass transition. The thermalization process starts with the system prepared in\na non-equilibrium state with the desired final volume fraction {\\phi} but with\na prescribed non-equilibrium static structure factor S_0(k; {\\phi}). The\nevolution of the {\\alpha}- relaxation time {\\tau}{\\alpha} (k) and long-time\nself-diffusion coefficient DL as a function of the evolution time tw is then\nmonitored for an array of volume fractions. For a given waiting time the plot\nof {\\tau}{\\alpha} (k; {\\phi}, tw) as a function of {\\phi} exhibits two regimes\ncorresponding to samples that have fully equilibrated within this waiting time\n({\\phi} \\leq {\\phi}(c) (tw)), and to samples for which equilibration is not yet\ncomplete ({\\phi} \\geq {\\phi}(c) (tw)). The crossover volume fraction {\\phi}(c)\n(tw) increases with tw but seems to saturate to a value {\\phi}(a) \\equiv\n{\\phi}(c) (tw \\rightarrow \\infty) \\approx 0.582. We also find that the waiting\ntime t^(eq)_w({\\phi}) required to equilibrate a system grows faster than the\ncorresponding equilibrium relaxation time, t^(eq)({\\phi}) \\approx 0.27 \\times\n[{\\tau}{\\alpha} (k; {\\phi})]^1.43, and that both characteristic times increase\nstrongly as {\\phi} approaches {\\phi}^(a), thus suggesting that the measurement\nof equilibrium properties at and above {\\phi}(a) is experimentally impossible."
    },
    {
        "anchor": "Generalized Einstein's and Brinkman's solutions for the effective\n  viscosity of nanofluids: In this paper, we derive the closed form analytical solutions for the\neffective viscosity of the suspensions of solid spheres that take into account\nthe size effects. This result is obtained using the solution for the effective\nshear modulus of particulate composites developed in the framework of the\nstrain gradient elasticity theory. Assuming incompressibility of matrix and\nrigid behavior of particles and using a mathematical analogy between the theory\nof elasticity and the theory of viscous fluids we derive the generalized\nEinstein's formula for the effective viscosity. Generalized Brinkman's solution\nfor the concentrated suspensions is derived then using differential method.\nObtained solutions contain single additional length scale parameter, which can\nbe related to the interactions between base liquid and solid particles in the\nsuspensions. In the case of the large ratio the between diameter of particles\nand the length scale parameter, developed solutions reduce to the classical\nsolutions, however for the small relative diameter of particles an increase of\nthe effective viscosity is predicted. It is shown that developed models agree\nwell with known experimental data. Solutions for the fibrous suspensions are\nalso derived and validated.",
        "positive": "Polymers pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium\n  with a Pore: We investigate polymer partitioning from polymer mixtures into nanometer size\ncavities by formulating an equation of state for a binary polymer mixture\nassuming that only one (smaller) of the two polymer components can penetrate\nthe cavity. Deriving the partitioning equilibrium equations and solving them\nnumerically allows us to introduce the concept of \"polymers-pushing-polymers\"\nfor the action of non-penetrating polymers on the partitioning of the\npenetrating polymers. Polymer partitioning into a pore even within a very\nsimple model of a binary polymer mixture is shown to depend in a complicated\nway on the composition of the polymer mixture and/or the pore-penetration\npenalty. This can lead to enhanced as well as diminished partitioning, due to\ntwo separate energy scales that we analyse in detail."
    },
    {
        "anchor": "Experimental evidence of the ferroelectric phase transition near the\n  $\u03bb-$point in liquid water: We studied dielectric properties of nano-sized liquid water samples confined\nin polymerized silicates MCM-41 characterized by the porous sizes \\sim 3-10nm.\nWe report the direct measurements of the dielectric constant by the dielectric\nspectroscopy method at frequencies 25Hz-1MHz and demonstrate clear signatures\nof the second-order phase transition of ferroelectric nature at temperatures\nnext to the \\lambda- point in the bulk supercooled water. The presented results\nsupport the previously developed polar liquid phenomenology and hence establish\nits applicability to model actual phenomena in liquid water.",
        "positive": "Chemically reactive thin films: dynamics and stability: Catalyst particles or complexes suspended in liquid films can trigger\nchemical reactions leading to inhomogeneous concentrations of reactants and\nproducts in the film. We demonstrate that the sensitivity of the liquid film's\ngas-liquid surface tension to these inhomogeneous concentrations strongly\nimpacts the film stability. Using linear stability analysis, we identify novel\nscenarios in which the film can be either stabilized or destabilized by the\nreactions. Furthermore, we find so far unrevealed rupture mechanisms which are\nabsent in the chemically inactive case. The linear stability predictions are\nconfirmed by numerical simulations, which also demonstrate that the shape of\nchemically active droplets can depart from the spherical cap and that unsteady\nstates such as traveling and standing waves might appear. Finally, we\ncritically discuss the relevance of our predictions by showing that the range\nof our selected parameters is well accessible by typical experiments."
    },
    {
        "anchor": "Shear-induced structuration of confined carbon black gels: Steady-state\n  features of vorticity-aligned flocs: Various dispersions of attractive particles are known to aggregate into\npatterns of vorticity-aligned stripes when sheared in confined geometries. We\nreport a thorough experimental investigation of such shear-induced vorticity\nalignment through direct visualization of carbon black gels in both simple\nplane shear and rotational shear cells. Control parameters such as the gap\nwidth, the strain rate, and the gel concentration are systematically varied. It\nis shown that in steady states the wavelength of the striped pattern depends\nlinearly on the gap width $h$ while being insensitive to both the gel\nconcentration $C$ and the shear rate $\\gp$. The width of the vorticity-aligned\nflocs coincides with the gap width and is also independent of $C$ and $\\gp$,\nwhich hints to a simple picture in terms of compressible cylindrical flocs.\nFinally, we show that there exists a critical shear rate $\\gp_c$ above which\nstructuration does not occur and that $\\gp_c$ scales as $h^{-\\alpha}$ with\n$\\alpha=1.4\\pm 0.1$ independently of $C$. This extensive data set should open\nthe way to quantitative modelling of the vorticity alignment phenomenon in\nattractive colloidal systems.",
        "positive": "Aging in humid granular media: Aging behavior is an important effect in the friction properties of solid\nsurfaces. In this paper we investigate the temporal evolution of the static\nproperties of a granular medium by studying the aging over time of the maximum\nstability angle of submillimetric glass beads. We report the effect of several\nparameters on these aging properties, such as the wear on the beads, the stress\nduring the resting period, and the humidity content of the atmosphere. Aging\neffects in an ethanol atmosphere are also studied. These experimental results\nare discussed at the end of the paper."
    },
    {
        "anchor": "Improved first order mean spherical approximation for simple fluids: A perturbation approach based on the first-order mean spherical approximation\n(FMSA) is proposed. It consists in adopting a hard-sphere plus short-range\nattractive Yukawa fluid as the novel reference system, over which the\nperturbative solution of the Ornstein-Zernike equation is performed. A choice\nof the optimal range of the reference attraction is discussed. The results are\ncompared against conventional FMSA/HS theory and Monte-Carlo simulation data\nfor compressibility factor and vapor-liquid phase diagrams of the medium-ranged\nYukawa fluid. Proposed theory keeps the same level of simplicity and\ntransparency, as the conventional FMSA/HS approach does, but shows to be more\naccurate.",
        "positive": "Angular dependence of coercivity in magnetic nanotubes: The nucleation field for infinite magnetic nanotubes, in the case of a\nmagnetic field applied parallel to the long axis of the tubes, is calculated as\na function of their geometric parameters and compared with those produced\ninside the pores of anodic alumina membranes by atomic layer deposition. We\nalso extended this result to the case of an angular dependence. We observed a\ntransition from curling-mode rotation to coherent-mode rotation as a function\nof the angle in which the external magnetic field is applied. Finally, we\nobserved that the internal radii of the tubes favors the magnetization curling\nreversal."
    },
    {
        "anchor": "Molecular Rotors for In Situ Viscosity Mapping during Evaporation of\n  Confined Fluid Mixtures: Numerous formulation processes of materials involve a drying step, during\nwhich evaporation of a solvent from a multi-component liquid mixture, often\nconfined in a thin film or in a droplet, lead to concentration and assembly of\nnon volatile compounds. While the basic phenomena ruling evaporation dynamics\nare known, a precise modeling of practical situations is hindered by the lack\nof tools for local and time-resolved mapping of concentration fields in such\nconfined systems. In this article, the use of Fluorescence Lifetime Imaging\nMicroscopy and of Fluorescent Molecular Rotors is introduced as a versatile,\nin-situ and quantitative method to map viscosity and concentration fields in\nconfined, evaporating liquids. More precisely, the cases of drying of a\nsuspended liquid film and of a sessile droplet of mixtures of fructose and\nwater is investigated. Measured viscosity and concentration fields allow to\ncharacterize drying dynamics, in agreement with simple modeling of the\nevaporation process.",
        "positive": "Stresses in non-equilibrium fluids: Exact formulation and coarse grained\n  theory: Starting from the stochastic equation for the density operator, we formulate\nthe exact (instantaneous) stress tensor for interacting Brownian particles,\nwhose average value agrees with expressions derived previously. We analyze the\nrelation between the stress tensor and forces on external potentials, and\nobserve that, out of equilibrium, particle currents give rise to extra forces.\nNext, we derive the stress tensor for a Landau-Ginzburg theory in\nnon-equilibrium situations, finding an expression analogous to that of the\nexact microscopic stress tensor, and discuss the computation of\nout-of-equilibrium (classical) Casimir forces. We use these relations to study\nthe spatio-temporal correlations of the stress tensor in a Brownian fluid,\nwhich we derive exactly to leading order in the interaction potential strength.\nWe observe that, after integration over time, the spatial correlations\ngenerally decay as power laws in space. These are expected to be of importance\nfor driven confined systems. We also show that divergence-free parts of the\nstress tensor do not contribute in the Green-Kubo relation for the viscosity."
    },
    {
        "anchor": "Conservation laws of an electro-active polymer: Ionic electro-active polymers (E.A.P.) is an active material consisting in a\npolyelectrolyte (for example Nafion). Such material is usually used as thin\nfilm sandwiched between two platinum electrodes. The polymer undergoes large\nbending motions when an electric field is applied across the thickness.\nConversely, a voltage can be detected between both electrodes when the polymer\nis suddenly bent. The solvent-saturated polymer is fully dissociated, releasing\ncations of small size. We used a continuous medium approach. The material is\nmodelled by the coexistence of two phases; it can be considered as a porous\nmedium where the deformable solid phase is the polymer backbone with fixed\nanions; the electrolyte phase is made of a solvent (usually water) with free\ncations. The microscale conservation laws of mass, linear momentum and energy\nand the Maxwell's equations are first written for each phase. The physical\nquantities linked to the interfaces are deduced. The use of an average\ntechnique applied to the two-phase medium finally leads to an Eulerian\nformulation of the conservation laws of the complete material. Macroscale\nequations relative to each phase provides exchanges through the interfaces. An\nanalysis of the balance equations of kinetic, potential and internal energy\nhighlights the 2 Mireille Tixier, Jo{\\\"e}l Pouget phenomena responsible of the\nconversion of one kind of energy into another, especially the dissipative ones\n: viscous frictions and Joule effect.",
        "positive": "Effect of polydispersity in concentrated magnetorheological fluids: Magnetorheological fluids (MRF) are smart materials of increasing interest\ndue to their great versatility in mechanical and mechatronic systems. As main\nrheological features, MRFs must present low viscosity in the absence of a\nmagnetic field (0.1 - 1.0 Pa.s) and high yield stress (50 - 100 kPa) when\nmagnetized, in order to optimize the magnetorheological effect. Such\nproperties, in turn, are directly influenced by the composition, volume\nfraction, size, and size distribution (polydispersity) of the particles, the\nlatter being an important piece in the improvement of these main properties. In\nthis context, the present work aims to analyze, through experiments and\nsimulations, the influence of polydispersity on the maximum packing fraction,\non the yield stress under field (on-state), and on the plastic viscosity in the\nabsence of field (off-state) of concentrated MRF (phi = 48.5 vol.%). Three\nblends of carbonyl iron powder in polyalphaolefin oil were prepared. These\nblends have the same mode, but different polydispersity indexes, ranging from\n0.46 to 1.44. Separate simulations show that the random close packing fraction\nincreases from about 68% to 80% as the polydispersity index increases over this\nrange. The on-state yield stress, in turn, is raised from 30 +/- 0.5 kPa to 42\n+/- 2 kPa (B ~ 0.57 T) and the off-state plastic viscosity, is reduced from 4.8\nPa.s to 0.5 Pa.s. Widening the size distributions, as is well known in the\nliterature, increases packing efficiency and reduces the viscosity of\nconcentrated dispersions, but beyond that, it proved to be a viable way to\nincrease the magnetorheological effect of concentrated MRF. The Brouwers model,\nwhich considers the void fraction in suspensions of particles with lognormal\ndistribution, was proposed as a possible hypothesis to explain the increase in\nyield stress under magnetic field."
    },
    {
        "anchor": "Profiles of static liquid-gas interfaces in axisymmetrical containers\n  under different accelerations: Second order perturbation solutions of profiles of bubbles suspended in\nliquid and liquid gas interfaces when liquid all sinks in the bottom under\ndifferent accelerations are derived. Six procedures are developed based on\nthese solutions, and they are divided into two types. One takes coordinates of\nendpoints of profiles as inputs, and the other takes liquid volume or gas\nvolume as inputs. Numerical simulation are performed with the Volume of Fluid\nmethod and numerical results are in good agreement with predictions of these\nprocedures. Besides, the bigger the acceleration, the more flatter the bubble\nwill be until all liquid sinks to the bottom. Effects of accelerations on\nbubbles shape must be considered. When liquid all sinks to the bottom,\npredictions of liquid volume with the same liquid meniscus height as inputs\ndiffers a lot under different accelerations. The most significant change of\nliquid volume is when Bond is much smaller than 1. Effects of accelerations and\nliquid contact angle on liquid gas interfaces must be considered during\nevaluating liquid residue, and these findings will be great helpful for liquid\nresidue measurement and fine management in space.",
        "positive": "Ionic liquid-electrode interface: classification of ions, saturation of\n  layers, and structure-determined potentials: With a single-electrode model, we investigated surface charge screening at an\nionic liquid-electrode interface. Using the obtained geometric packing\ndensities, we estimated structure-determined potentials and capacitance values\nfor 40 studied ions. By comparing the predictions with the empirical data, we\nshow that exact surface charge screening by a monolayer of counter-ions (as\nwell as crowding of ions) is improbable for common ions within their\nelectrochemical stability window. We also predict that theoretically such a\nscreening state is possible for frisbee-shape ions."
    },
    {
        "anchor": "Fluid-fluid versus fluid-solid demixing in mixtures of parallel hard\n  hypercubes: It is well known that the increase of the spatial dimensionality enhances the\nfluid-fluid demixing of a binary mixture of hard hyperspheres, i.e. the\ndemixing occurs for lower mixture size asymmetry as compared to the\nthree-dimensional case. However, according to simulations, in the latter\ndimension the fluid-fluid demixing is metastable with respect to the\nfluid-solid transition. According to the results obtained from approximations\nto the equation of state of hard hyperspheres in higher dimensions, the\nfluid-fluid demixing might becomes stable for high enough dimension. However,\nthis conclusion is rather speculative since none of the above works have taken\ninto account the stability of the crystalline phase (nor by a minimization of a\ngiven density functional, neither spinodal calculations or MC simulations). Of\ncourse, the lack of results is justified by the difficulty for performing\ndensity functional calculations or simulations in high dimensions and, in\nparticular, for highly asymmetric binary mixtures. In the present work, we will\ntake advantage of a well tested theoretical tool, namely the fundamental\nmeasure density functional theory for parallel hard hypercubes (in the\ncontinuum and in the hypercubic lattice). With this, we have calculated the\nfluid-fluid and fluid-solid spinodals for different spatial dimensions. We have\nobtained, no matter of the dimensionality, the mixture size asymmetry nor the\npolydispersity (included as a bimodal distribution function centered around the\nasymmetric edge-lengths), that the fluid-fluid critical point is always located\nabove the fluid-solid spinodal. In conclusion, these results point to the\nexistence of demixing between at least one solid phase rich in large particles\nand one fluid phase rich in small ones, preempting a fluid-fluid demixing,\nindependently of the spatial dimension or the polydispersity.",
        "positive": "Electro-osmosis at surfactant-laden liquid-gas interfaces: beyond\n  standard models: Electro-osmosis (EO) is a powerful tool to manipulate liquids in micro and\nnanofluidic systems. While EO has been studied extensively at liquid-solid\ninterfaces, the case of liquid-vapor interfaces, found e.g. in foam films and\nbubbles, remains to be explored. Here we perform molecular dynamics (MD)\nsimulations of EO in a film of aqueous electrolyte covered with fluid layers of\nionic surfactants and surrounded by gas. Following the experimental procedure,\nwe compute the zeta potential from the EO velocity, defined as the velocity\ndifference between the middle of the liquid film and the surrounding gas. We\nshow that the zeta potential can be smaller or larger than existing predictions\ndepending on the surfactant coverage. We explain the failure of previous\ndescriptions by the fact that surfactants and bound ions move as rigid bodies\nand do not transmit the electric driving force to the liquid locally.\nConsidering the reciprocal streaming current effect, we then develop an\nextended model, which can be used to predict the experimental zeta potential of\nsurfactant-laden liquid-gas interfaces."
    },
    {
        "anchor": "Molecular Dynamics Simulation of Folding and Diffusion of Proteins in\n  Nanopores: A novel combination of discontinuous molecular dynamics and the Langevin\nequation, together with an intermediate-resolution model, are used to carry out\nlong (several $\\mu$s) simulation and study folding transition and transport of\nproteins in slit nanopores. Both attractive ($U^+$) and repulsive ($U^-$)\ninteraction potentials between the proteins and the pore walls are considered.\nNear the folding temperature $T_f$ and in the presence of $U^+$ the proteins\nundergo a repeating sequence of folding/partially-folding/ unfolding\ntransitions, while $T_f$ decreases with decreasing pore sizes. The opposite is\ntrue when $U^-$ is present. The proteins' effective diffusivity $D$ is computed\nas a function of their length (number of the amino acid groups), temperature\n$T$, the pore size, and the interaction potentials $U^\\pm$. Far from $T_f$, $D$\nincreases (roughly) linearly with $T$, but due to the thermal fluctuations and\ntheir effect on the proteins' structure near $T_f$, the dependence of $D$ on\n$T$ in this region is nonlinear. Under certain conditions, transport of\nproteins in smaller pores can be {\\it faster} than that in larger pores.",
        "positive": "Enhanced electro-actuation in dielectric elastomers: the non-linear\n  effect of free ions: Plasticized poly(vinyl chloride) (PVC) is a jelly-like soft dielectric\nmaterial that attracted substantial interest recently as a new type of\nelectro-active polymers. Under electric fields of several hundred Volt/mm, PVC\ngels undergo large deformations. These gels can be used as artificial muscles\nand other soft robotic devices, with striking deformation behavior that is\nquite different from conventional dielectric elastomers. Here, we present a\nsimple model for the electro-activity of PVC gels, and show a non-linear effect\nof free ions on its dielectric behaviors. It is found that their particular\ndeformation behavior is due to an electro-wetting effect and to a change in\ntheir interfacial tension. In addition, we derive analytical expressions for\nthe surface tension as well as for the apparent dielectric constant of the gel.\nThe theory indicates that the size of the mobile free ions has a crucial role\nin determining the electro-induced deformation, opening up the way to novel and\ninnovative designs of electro-active gel actuators."
    },
    {
        "anchor": "Two-step electrical percolation in nematic liquid crystal filled by\n  multiwalled carbon nanotubes: Percolation of carbon nanotubes (CNTs) in liquid crystals (LCs) opens way for\na unique class of anisotropic hybrid materials with a complex dielectric\nconstant widely controlled by CNT concentration. Percolation in such systems is\ncommonly described as a one-step process starting at a very low loading of\nCNTs. In the present study the two-step percolation was observed in the samples\nof thickness 250 $\\mu$m obtained by pressing the suspension between two\nsubstrates. The percolation concentrations for the first and second percolation\nprocesses were $C_n^{p_1}\\approx 0.0002$ wt. \\% and $C_n^{p_2}\\approx 0.5$ wt.\n\\%, respectively. The two-stage nature of percolation was explained on a base\nof mean field theory assuming core-shell structure of CNTs.",
        "positive": "Better than counting: Density profiles from force sampling: Calculating one-body density profiles in equilibrium via particle-based\nsimulation methods involves counting of events of particle occurrences at\n(histogram-resolved) space points. Here we investigate an alternative method\nbased on a histogram of the local force density. Via an exact sum rule the\ndensity profile is obtained with a simple spatial integration. The method\ncircumvents the inherent ideal gas fluctuations. We have tested the method in\nMonte Carlo, Brownian Dynamics and Molecular Dynamics simulations. The results\ncarry a statistical uncertainty smaller than that of the standard, counting,\nmethod, reducing therefore the computation time."
    },
    {
        "anchor": "The Abelian sandpile; a mathematical introduction: We give a simple rigourous treatment of the classical results of the abelian\nsandpile model. Although we treat results which are well-known in the physics\nliterature, in many cases we did not find complete proofs in the literature.\nThe paper tries to fill the gap between the mathematics and the physics\nliterature on this subject, and also presents some new proofs. It can also\nserve as an introduction to the model.",
        "positive": "Sound speed in water-saturated glass beads as a function of frequency\n  and porosity: Sound propagation in water-saturated granular sediments is known to depend on\nthe sediment porosity, but few data in the literature address both the\nfrequency and porosity dependency. To begin to address this deficiency, a\nfluidized bed technique was used to control the porosity of an artificial\nsediment composed of glass spheres of 265 {\\mu}m diameter. Time-of-flight\nmeasurements and the Fourier phase technique were utilized to determine the\nsound speed for frequencies from 300 to 800 kHz and porosities from 0.37 to\n0.43. A Biot-based model qualitatively describes the porosity dependence."
    },
    {
        "anchor": "Phase separation of an asymmetric binary fluid mixture confined in a\n  nanoscopic slit pore: Molecular-dynamics simulations: As a generic model system of an asymmetric binary fluid mixture, hexadecane\ndissolved in carbon dioxide is considered, using a coarse-grained bead-spring\nmodel for the short polymer, and a simple spherical particle with Lennard-Jones\ninteractions for the carbon dioxide molecules. In previous work, it has been\nshown that this model reproduces the real phase diagram reasonable well, and\nalso the initial stages of spinodal decomposition in the bulk following a\nsudden expansion of the system could be studied. Using the parallelized\nsimulation package ESPResSo on a multiprocessor supercomputer, phase separation\nof thin fluid films confined between parallel walls that are repulsive for both\ntypes of molecules are simulated in a rather large system (1356 x 1356 x 67.8\nA^3, corresponding to about 3.2 million atoms). Following the sudden system\nexpansion, a complicated interplay between phase separation in the directions\nperpendicular and parallel to the walls is found: in the early stages the\nhexadecane molecules accumulate mostly in the center of the slit pore, but as\nthe coarsening of the structure in the parallel direction proceeds, the\ninhomogeneity in the perpendicular direction gets much reduced. Studying then\nthe structure factors and correlation functions at fixed distances from the\nwall, the densities are essentially not conserved at these distances, and hence\nthe behavior differs strongly from spinodal decomposition in the bulk. Some of\nthe characteristic lengths show a nonmonotonic variation with time, and simple\ncoarsening described by power-law growth is only observed if the domain sizes\nare much larger than the film thickness.",
        "positive": "Long-range interactions in randomly driven granular fluids: We study the long-range spatial correlations in the nonequilibrium steady\nstate of a randomly driven granular fluid with the emphasis on obtaining the\nexplicit form of the static structure factors. The presence of immobile\nparticles immersed in such a fluidized bed of fine particles leads to the\nconfinement of the fluctuation spectrum of the hydrodynamic fields, which\nresults in effective long-range interactions between the intruders. The\nanalytical predictions are in agreement with the results of discrete element\nmethod simulations. By changing the shape and orientation of the intruders, we\naddress how the effective force is affected by small changes in the boundary\nconditions."
    },
    {
        "anchor": "Local field distribution near corrugated interfaces: Green's function\n  formulation: We have developed a Green's function formalism to compute the local field\ndistribution near an interface separating two media of different dielectric\nconstants. The Maxwell's equations are converted into a surface integral\nequation; thus it greatly simplifies the solutions and yields accurate results\nfor interfaces of arbitrary shape. The integral equation is solved and the\nlocal field distribution is obtained for a periodic interface.",
        "positive": "Emergent spatial structures in flocking models: a dynamical system\n  insight: We show that hydrodynamic theories of polar active matter generically possess\ninhomogeneous traveling solutions. We introduce a unifying dynamical-system\nframework to establish the shape of these intrinsically nonlinear patterns, and\nshow that they correspond to those hitherto observed in experiments and\nnumerical simulations: periodic density waves, and solitonic bands, or\npolar-liquid droplets both cruising in isotropic phases. We elucidate their\nrespective multiplicity and mutual relations, as well as their existence\ndomain."
    },
    {
        "anchor": "The mean-field dividing interface is united with the Widom line: We define a mean-field crossover generated by the Maxwell construction as the\ndividing interface for the vapor-liquid interface area and a highly accurate\ndensity-profile equation is thus derived. By using a mean-field equation of\nsate for the Lennard-Jones fluid incorporated with the density gradient theory,\nwe show that the intrinsic free energy peaks and the isobaric heat capacity\nexhibits local maxima at the interface. We demonstrate that the mean-field\ninterface is the natural extension of the Widom line into the coexistence\nregion, hence the entire space is coherently divided into liquid-like and\ngas-like regions in all three (temperature-pressure-volume) planes. Finally,\nthe mean-field theory is found holding all the information for composing the\nphase diagrams over the entire phase space.",
        "positive": "Monte Carlo Study of Patchy Nanostructures Self-Assembled from a Single\n  Multiblock Chain: We present a lattice Monte Carlo simulation for a multiblock copolymer chain\nof length N=240 and microarchitecture $(10-10)_{12}$.The simulation was\nperformed using the Monte Carlo method with the Metropolis algorithm. We\nmeasured average energy, heat capacity, the mean squared radius of gyration,\nand the histogram of cluster count distribution. Those quantities were\ninvestigated as a function of temperature and incompatibility between segments,\nquantified by parameter {\\omega}. We determined the temperature of the\ncoil-globule transition and constructed the phase diagram exhibiting a variety\nof patchy nanostructures. The presented results yield a qualitative agreement\nwith those of the off-lattice Monte Carlo method reported earlier, with a\nsignificant exception for small incompatibilities,{\\omega}, and low\ntemperatures, where 3-cluster patchy nanostructures are observed in contrast to\nthe 2-cluster structures observed for the off-lattice $(10-10)_{12}$ chain. We\nattribute this difference to a considerable stiffness of lattice chains in\ncomparison to that of the off-lattice chains."
    },
    {
        "anchor": "Stability of topological wall defects on spheres with n-atic order: Topological point defects on orientationally ordered spheres, and on\ndeformable fluid vesicles have been partly motivated by their potential\napplications in creating super-atoms with directional bonds through\nfunctionalization of the \"bald-spots\" created by topological point defects,\nthus paving the way for atomic chemistry at micron scales. We show that\nsingular wall defects, topologically unstable \"bald lines\" in two dimensions,\nare stabilized near the order-disorder transition on a sphere. We attribute\ntheir stability to free-energetic considerations, which override those of\ntopological stability.",
        "positive": "Power-law scaling in granular rheology across flow geometries: Based on discrete element method simulations, we propose a new form of the\nconstitution equation for granular flows independent of packing fraction.\nRescaling the stress ratio $\\mu$ by a power of dimensionless temperature\n$\\Theta$ makes the data from a wide set of flow geometries collapse to a master\ncurve depending only on the inertial number $I$. The basic power-law structure\nappears robust to varying particle properties (e.g. surface friction) in both\n2D and 3D systems. We show how this rheology fits and extends frameworks such\nas kinetic theory and the Nonlocal Granular Fluidity model."
    },
    {
        "anchor": "Alveolar mimics with periodic strain and its effect on the cell layer\n  formation: We report on the development of a new model of alveolar air-tissue interface\non a chip. The model consists of an array of suspended hexagonal monolayers of\ngelatin nanofibers supported by microframes and a microfluidic device for the\npatch integration. The suspended monolayers are deformed to a central\ndisplacement of 40-80 um at the air-liquid interface by application of air\npressure in the range of 200-1000 Pa. With respect to the diameter of the\nmonolayers that is 500 um, this displacement corresponds to a linear strain of\n2-10% in agreement with the physiological strain range in the lung alveoli. The\nculture of A549 cells on the monolayers for an incubation time 1-3 days showed\nviability in the model. We exerted a periodic strain of 5% at a frequency of\n0.2 Hz during 1 hour to the cells. We found that the cells were strongly\ncoupled to the nanofibers, but the strain reduced the coupling and induced\nremodeling of the actin cytoskeleton, which led to a better tissue formation.\nOur model can serve as a versatile tool in lung investigations such as in\ninhalation toxicology and therapy.",
        "positive": "Layering of magnetic nanoparticles at amorphous magnetic templates with\n  perpendicular anisotropy: We reveal the assembly of monodisperse magnetite nanoparticles of sizes 5 nm,\n15 nm and 25 nm from dilute water-based ferrofluids onto an amorphous magnetic\ntemplate with out-of-plane anisotropy. From neutron reflectometry experiments\nwe extract density profiles and show that the particles self-assemble into\nlayers at the magnetic surface. The layers are extremely stable against\ncleaning and rinsing of the substrate. The density of the layers is determined\nby and increases with the remanent magnetic moment of the particles."
    },
    {
        "anchor": "Moving Manifolds in Electromagnetic Fields: We propose dynamic non-linear equations for moving surfaces in\nelectromagnetic field. The field is induced by a material body with a boundary\nof the surface. Correspondingly the potential energy, set by the field at the\nboundary, can be written as an addition of four-potential times four-current to\na contraction of electromagnetic tensor. Proper application of minimal action\nprinciple to the system Lagrangian yields dynamic non-linear equations for\nmoving three dimensional manifolds in electromagnetic fields. The equations, in\ndifferent conditions simplify to Maxwell equations for massless three surfaces,\nto Euler equations for dynamic fluid, to magneto-hydrodynamic equations and to\nPoisson-Boltzmann equation. To illustrate effectiveness of the equations of\nmotion we apply the formalism to analyze dynamics of macro-molecules and\nmembranes.",
        "positive": "Deposit Growth in the Wetting of an Angular Region with Uniform\n  Evaporation: Solvent loss due to evaporation in a drying drop can drive capillary flows\nand solute migration. The flow is controlled by the evaporation profile and the\ngeometry of the drop. We predict the flow and solute migration near a sharp\ncorner of the perimeter under the conditions of uniform evaporation. This\nextends the study of Ref. 6, which considered a singular evaporation profile,\ncharacteristic of a dry surrounding surface. We find the rate of the deposit\ngrowth along contact lines in early and intermediate time regimes. Compared to\nthe dry-surface evaporation profile of Ref. 6, uniform evaporation yields more\nsingular deposition in the early time regime, and nearly uniform deposition\nprofile is obtained for a wide range of opening angles in the intermediate time\nregime. Uniform evaporation also shows a more pronounced contrast between acute\nopening angles and obtuse opening angles."
    },
    {
        "anchor": "Stiffening Thermal Membranes by Cutting: Two-dimensional crystalline membranes have recently been realized\nexperimentally in such systems as graphene and molybdenum disulfide, sparking a\nresurgence in interest in their statistical properties. Thermal fluctuations\ncan significantly affect the effective mechanical properties of properly\nthermalized membranes, renormalizing both bending rigidity and elastic moduli\nso that in particular they become stiffer to bending than their bare bending\nrigidity would suggest. We use molecular dynamics simulations to examine how\nthe mechanical behavior of thermalized two-dimensional clamped ribbons\n(cantilevers) depends on their precise topology and geometry. We find that a\nsimple slit smooths roughness as measured by the variance of height\nfluctuations. This counterintuitive effect may be due to the counter-posed\ncoupling of the lips of the slit to twist in the intact regions of the ribbon.",
        "positive": "Surface tension of bulky colloids, capillarity under gravity and the\n  microscopic origin of the Kardar-Parisi-Zhang equation: Experimental measurements of the surface tension of colloidal interfaces have\nlong been in conflict with computer simulations. In this work we show that the\nsurface tension of colloids as measured by surface fluctuations picks up a\ngravity dependent contribution which removes the discrepancy. The presence of\nthis term puts a strong constraint on the structure of the interface which\nallows one to identify corrections to the fundamental equation of equilibrium\ncapillarity and deduce bottom-up the microscopic origin of a growth model with\nclose relation to the Kardar-Parisi-Zhang equation."
    },
    {
        "anchor": "Wetting and wrapping of a floating droplet by a thin elastic filament: We study the wetting of a thin elastic filament floating on a fluid surface\nby a droplet of another, immiscible fluid. This quasi-2D experimental system is\nthe lower-dimensional counterpart of the wetting and wrapping of a droplet by\nan elastic sheet. The simplicity of this system allows us to study the\nphenomenology of partial wetting and wrapping of the droplet by measuring\nangles of contact as a function of the elasticity of the filament, the applied\ntension and the curvature of the droplet. We find that a purely geometric\ntheory gives a good description of the mechanical equilibria in the system. The\nestimates of applied tension and tension in the filament obey an elastic\nversion of the Young-Laplace-Dupr\\'e relation. However, curvatures close to the\ncontact line are not captured by the geometric theory, possibly because of 3D\neffects at the contact line. We also find that when a highly-bendable filament\ncompletely wraps the droplet, there is continuity of curvature at the\ndroplet-filament interface, leading to seamless wrapping as observed in a 3D\ndroplet.",
        "positive": "Nonequilibrium master kinetic equation modelling of colloidal gelation: We present a detailed study of the kinetic cluster growth process during\ngelation of weakly attractive colloidal particles by means of experiments on\ncritical Casimir attractive colloidal systems, simulations and analytical\ntheory. In the experiments and simulations, we follow the mean coordination\nnumber of the particles during the growth of clusters to identify an\nattractive-strength independent cluster evolution as a function of mean\ncoordination number. We relate this cluster evolution to the kinetic attachment\nand detachment rates of particles and particle clusters. We find that\nsingle-particle detachment dominates in the relevant weak attractive-strength\nregime, while association rates are almost independent of the cluster size.\nUsing the limit of single-particle dissociation and size-independent\nassociation rates, we solve the master kinetic equation of cluster growth\nanalytically to predict power-law cluster mass distributions with exponents\n$-3/2$ and $-5/2$ before and after gelation, respectively, which are consistent\nwith the experimental and simulation data. These results suggest that the\nobserved critical Casimir-induced gelation is a second-order nonequilibrium\nphase transition (with broken detailed balance). Consistent with this scenario,\nthe size of the largest cluster is observed to diverge with power-law exponent\naccording to three-dimensional percolation upon approaching the critical mean\ncoordination number."
    },
    {
        "anchor": "Charged colloids at low ionic strength: macro- or microphase separation?: Phase separation in charged systems may involve the replacement of critical\npoints by microphase separated states, or charge-density-wave states. A density\nfunctional theory for highly charged colloids at low ionic strength is\ndeveloped to examine this possibility. It is found that the lower critical\nsolution point is most susceptible to microphase separation. Moreover the\ntendency can be quantified, and related to the importance of small ion entropy\nin suppressing phase separation at low added salt. The theory also gives\ninsights into the colloid structure factor in these systems.",
        "positive": "An iterative algorithm to improve colloidal particle locating: Confocal microscopy of colloids combined with digital image processing has\nbecome a powerful tool in soft matter physics and materials science. Together,\nthese techniques enable locating and tracking of more than half a million\nindividual colloidal particles at once. However, despite improvements in\nlocating algorithms that improve position accuracy, it remains challenging to\nlocate all particles in a densely-packed, three dimensional colloid without\nerroneously identifying the same particle more than once. We present a simple,\niterative algorithm that mitigates both the \"missed particle\" and \"double\ncounting\" problems while simultaneously reducing sensitivity to the specific\nchoice of input parameters. It is also useful for analyzing images with\nspatially-varying brightness in which a single set of input parameters is not\nappropriate for all particles. The algorithm is easy to implement and\ncompatible with existing particle locating software."
    },
    {
        "anchor": "Simulations of liquid crystal hydrodynamics: We present a lattice Boltzmann algorithm for liquid crystal hydrodynamics.\nThe coupling between the tensor order parameter and the flow is treated\nconsistently allowing investigation of a wide range of non-Newtonian flow\nbehavior. We present results for the effect of hydrodynamics on defect\ncoalescence; of the appearance of the log-rolling and kayaking states in\nPoiseuille flow; and for banding and coexistence of isotropic and nematic\nphases under shear.",
        "positive": "Active Brownian particles near straight or curved walls: Pressure and\n  boundary layers: Unlike equilibrium systems, active matter is not governed by the conventional\nlaws of thermodynamics. Through a series of analytic calculations and Langevin\ndynamics simulations, we explore how systems cross over from equilibrium to\nactive behavior as the activity is increased. In particular, we calculate the\nprofiles of density and orientational order near straight or circular walls,\nand show the characteristic width of the boundary layers. We find a simple\nrelationship between the enhancements of density and pressure near a wall.\nBased on these results, we determine how the pressure depends on wall\ncurvature, and hence make approximate analytic predictions for the motion of\ncurved tracers, as well as the rectification of active particles around small\nopenings in confined geometries."
    },
    {
        "anchor": "Mesoscopic helical models for DNA: Nucleic acids physical properties have been investigated by theoretical\nmethods based both on fully atomistic representations and on coarse grained\nmodels, e.g. the worm-like-chain, taken from polymer physics. In this article,\nI present an intermediate (mesoscopic) approach and show how to build a three\ndimensional Hamiltonian model which accounts for the main interactions\nresponsible for the stability of the helical molecules. While the 3D mesoscopic\nmodel yields a sufficiently detailed description of the helix at the level of\nthe base pair, it also allows one to predict the thermodynamical and structural\nproperties of molecules in solution. Relying on the idea that the base pair\nfluctuations can be conceived as trajectories, I have built a computational\nmethod based on the time dependent path integral formalism to derive the\npartition function. While the main features of the method are presented, I\nfocus here in particular on a newly developed statistical method to set the\nmaximum amplitude of the base pair fluctuations, a key parameter of the theory.\nSome applications to the calculation of DNA flexibility properties are\ndiscussed together with the available experimental data.",
        "positive": "Spacial and temporal dynamics of the volume fraction of the colloidal\n  particles inside a drying sessile drop: Using lubrication theory, drying processes of sessile colloidal droplets on a\nsolid substrate are studied. A simple model is proposed to describe temporal\ndynamics both the shape of the drop and the volume fraction of the colloidal\nparticles inside the drop. The concentration dependence of the viscosity is\ntaken into account. It is shown that the final shapes of the drops depend on\nboth the initial volume fraction of the colloidal particles and the capillary\nnumber. The results of our simulations are in a reasonable agreement with the\npublished experimental data. The computations for the drops of aqueous solution\nof human serum albumin (HSA) are presented."
    },
    {
        "anchor": "Active temperature and velocity correlations produced by a swimmer\n  suspension: The agitation produced in a fluid by a suspension of micro-swimmers in the\nlow Reynolds number limit is studied. In this limit, swimmers are modeled as\nforce dipoles all with equal strength. The agitation is characterized by the\nactive temperature defined, as in kinetic theory, as the mean square velocity,\nand by the equal-time spatial correlations. Considering the phase in which the\nswimmers are homogeneously and isotropically distributed in the fluid, it is\nshown that the active temperature and velocity correlations depend on a single\nscalar correlation function of the dipole-dipole correlation function. By\nmaking a simple medium range oder model, in which the dipole-dipole correlation\nfunction is characterized by a single correlation length $k_0^{-1}$ it is\npossible to make quantitative predictions. It is found that the active\ntemperature depends on the system size, scaling as $L^{4-d}$ at large\ncorrelation lengths $L\\ll k_0^{-1}$, while in the opposite limit it saturates\nin three dimensions and diverges logarithmically with the system size in two\ndimensions. In three dimensions he velocity correlations decay as $1/r$ for\nsmall correlation lengths, while at large correlation lengths the transverse\ncorrelation function becomes negative at maximum separation $r\\sim L/2$, effect\nthat disappears as the system increases in size.",
        "positive": "Theory of colloidal stabilization by unattached polymers: Stable colloidal dispersions with evenly distributed particles are important\nfor many technological applications. Due to Brownian motion colloidal particles\nhave constant collisions with each other which often lead to their aggregation\ndriven by the long range van der Waals attraction. As a result the colloidal\nsystems often tend to precipitate. A number of methods have been devised to\nminimize the effect of long-range van der Waals attraction between colloidal\nparticles or to override the influence of the attraction in order to provide\nthe colloidal stability.In the PhD thesis we investigated the colloidal\nstabilization in solutions of free polymers which is commonly referred to as\ndepletion stabilization. Previous theoretical studies of free-polymer induced\n(FPI) stabilization were based on oversimplified models involving uncontrolled\napproximations. Even the most basic features of the depletion stabilization\nphenomenon were unknown. It was unclear how the PI repulsion depends on the\nsolution parameters, polymer structure and monomer/surface interactions.The\nfree polymer chains were modeled as random walks in a self-consistent molecular\nfield that satisfied to diffusion-like integro-differential equation. As the\nmolecular field we used the chemical potential that for semi-dilute polymer\nsolution can be represented as a virial expansion where we took into account\nonly second and third virial coefficients of the polymer solution. Varying the\nparameters like polymer stiffness, polymer length, polymer concentration and\nsolvent regime (like theta solvent) whether it is for purely repulsive\ncolloidal surface, adsorbed surface or surface with grafted polymer layer we\nwere able to enhance the repulsive barrier due to the free polymers between the\nparticles and therefore found conditions for kinetic stabilization of the\nsystem."
    },
    {
        "anchor": "Euler-Poincar\u00e9 approaches to nematodynamics: Nematodynamics is the orientation dynamics of flowless liquid-crystals. We\nshow how Euler-Poincar\\'e reduction produces a unifying framework for various\ntheories, including Ericksen-Leslie, Luhiller-Rey, and Eringen's micropolar\ntheory. In particular, we show that these theories are all compatible with each\nother and some of them allow for more general configurations involving a non\nvanishing discination density. All results are also extended to flowing liquid\ncrystals.",
        "positive": "On the modulational stability of Gross-Pitaevskii type equations in 1+1\n  dimensions: The modulational stability of the nonlinear Schr{\\\"o}dinger (NLS) equation is\nexamined in the case with a quadratic external potential. This study is\nmotivated by recent experimental studies in the context of matter waves in\nBose-Einstein condensates (BECs). The theoretical analysis invokes a lens-type\ntransformation that converts the Gross-Pitaevskii into a regular NLS equation\nwith an additional growth term. This analysis suggests the particular interest\nof a specific time-varying potential ((t+t*)^{-2}). We examine both this\npotential, as well as the time independent one numerically and conclude by\nsuggesting experiments for the production of solitonic wave-trains in BEC."
    },
    {
        "anchor": "An All-Electric Single-Molecule Hybridisation Detector for short DNA\n  Fragments: In combining DNA nanotechnology and high-bandwidth single-molecule detection\nin nanopipettes, we demonstrate an all-electric, label-free hybridisation\nsensor for short DNA sequences (< 100 nt). Such short fragments are known to\noccur as circulating cell-free DNA in various bodily fluids, such as blood\nplasma and saliva, and have been identified as disease markers for cancer and\ninfectious diseases. To this end, we use as a model system a 88-mer target from\nthe RV1910c gene in Mycobacterium tuberculosis that is associated with\nantibiotic (isoniazid) resistance in TB. Upon binding to short probes attached\nto long carrier DNA, we show that resistive pulse sensing in nanopipettes is\ncapable of identifying rather subtle structural differences, such as the\nhybridisation state of the probes, in a statistically robust manner. With\nsignificant potential towards multiplexing and high-throughput analysis, our\nstudy points towards a new, single-molecule DNA assay technology that is fast,\neasy to use and compatible with point of care environments.",
        "positive": "Landau-deGennes Theory of Biaxial Nematics Re-examined: Recent experiments report that the long looked for thermotropic biaxial\nnematic phase has been finally detected in some thermotropic liquid crystalline\nsystems. Inspired by these experimental observations we concentrate on some\nelementary theoretical issues concerned with the classical sixth-order\nLandau-deGennes free energy expansion in terms of the symmetric and traceless\ntensor order parameter $Q_{\\alpha\\beta}$. In particular, we fully explore the\nstability of the biaxial nematic phase giving analytical solutions for all\ndistinct classes of the phase diagrams that theory allows. This includes\ndiagrams with triple- and (tri-)critical points and with multiple (reentrant)\nbiaxial- and uniaxial phase transitions. A brief comparison with predictions of\nexisting molecular theories is also given."
    },
    {
        "anchor": "Can phoretic particles swim in two dimensions?: Artificial phoretic particles swim using self-generated gradients in chemical\nspecies (self-diffusiophoresis) or charges and currents (self-electrophoresis).\nThese particles can be used to study the physics of collective motion in active\nmatter and might have promising applications in bioengineering. In the case of\nself-diffusiophoresis, the classical physical model relies on a steady solution\nof the diffusion equation, from which chemical gradients, phoretic flows and\nultimately the swimming velocity, may be derived. Motivated by disk-shaped\nparticles in thin films and under confinement, we examine the extension to two\ndimensions. Because the two-dimensional diffusion equation lacks a steady state\nwith the correct boundary conditions, Laplace transforms must be used to study\nthe long-time behavior of the problem and determine the swimming velocity. For\nfixed chemical fluxes on the particle surface, we find that the swimming\nvelocity ultimately always decays logarithmically in time. In the case of\nfinite Peclet numbers, we solve the full advection-diffusion equation\nnumerically and show that this decay can be avoided by the particle moving to\nregions of unconsumed reactant. Finite advection thus regularizes the\ntwo-dimensional phoretic problem.",
        "positive": "Curved Tails in Polymerization-Based Bacterial Motility: The curved actin ``comet-tail'' of the bacterium Listeria monocytogenes is a\nvisually striking signature of actin polymerization-based motility. Similar\nactin tails are associated with Shigella flexneri, spotted-fever Rickettsiae,\nthe Vaccinia virus, and vesicles and microspheres in related in vitro systems.\nWe show that the torque required to produce the curvature in the tail can arise\nfrom randomly placed actin filaments pushing the bacterium or particle. We find\nthat the curvature magnitude determines the number of actively pushing\nfilaments, independent of viscosity and of the molecular details of force\ngeneration. The variation of the curvature with time can be used to infer the\ndynamics of actin filaments at the bacterial surface."
    },
    {
        "anchor": "Interface deformations affect the orientation transition of magnetic\n  ellipsoidal particles adsorbed at fluid-fluid interfaces: Manufacturing new soft materials with specific optical, mechanical and\nmagnetic properties is a significant challenge. Assembling and manipulating\ncolloidal particles at fluid interfaces is a promising way to make such\nmaterials. We use lattice-Boltzmann simulations to investigate the response of\nmagnetic ellipsoidal particles adsorbed at liquid-liquid interfaces to external\nmagnetic fields. We provide further evidence for the first-order orientation\nphase transition predicted by Bresme and Faraudo [Journal of Physics: Condensed\nMatter 19 (2007), 375110]. We show that capillary interface deformations around\nthe ellipsoidal particle significantly affect the tilt-angle of the particle\nfor a given dipole-field strength, altering the properties of the orientation\ntransition. We propose scaling laws governing this transition, and suggest how\nto use these deformations to facilitate particle assembly at fluid-fluid\ninterfaces.",
        "positive": "Quantifying dynamics of the financial correlations: A novel application of the correlation matrix formalism to study dynamics of\nthe financial evolution is presented. This formalism allows to quantify the\nmemory effects as well as some potential repeatable intradaily structures in\nthe financial time-series. The present study is based on the high-frequency\nDeutsche Aktienindex (DAX) data over the time-period between November 1997 and\nDecember 1999 and demonstrates a power of the method. In this way two\nsignificant new aspects of the DAX evolution are identified: (i) the memory\neffects turn out to be sizably shorter than what the standard autocorrelation\nfunction analysis seems to indicate and (ii) there exist short term repeatable\nstructures in fluctuations that are governed by a distinct dynamics. The former\nof these results may provide an argument in favour of the market efficiency\nwhile the later one may indicate origin of the difficulty in reaching a\nGaussian limit, expected from the central limit theorem, in the distribution of\nreturns on longer time-horizons."
    },
    {
        "anchor": "On the origin of order: A cardinal feature common to embryonic development and tissue reorganization,\nas well as to wound healing and cancer cell invasion, is collective cellular\nmigration. During collective migratory events the phenomena of cell jamming and\nunjamming are increasingly recognized, and underlying mechanical, genomic,\ntranscriptional, and signaling events are increasingly coming to light. In this\nbrief perspective I propose a synthesis that brings together for the first time\ntwo key concepts. On the one hand, it has been suggested that the unjammed\nphase of the cellular collective evolved under a selective pressure favoring\nfluid-like migratory dynamics as would be required so as to accommodate\nepisodes of tissue evolution, development, plasticity, and repair. Being\ndynamic, such an unjammed phase is expected to be energetically expensive\ncompared with the jammed phase, which evolved under a selective pressure\nfavoring a solid-like homeostatic regime that, by comparison, is non-migratory\nbut energetically economical and mechanically stable. On the other hand, well\nbefore the discovery of cell jamming Kauffman proposed the general biological\nprinciple that living systems exist in a solid regime near the edge of chaos,\nand that natural selection achieves and sustains such a poised state. Here I\npropose that, in certain systems at least, this poised state as predicted in\nthe abstract by Kaufmann is realized in the particular by the jammed regime\njust at the brink of unjamming.",
        "positive": "Rate Equations for Sympathetic Cooling of Trapped Bosons or Fermions: We derive two different sets of rate equations for sympathetic cooling of\nharmonically trapped Bosons or Fermions. The rate equations are obtained from a\nmaster equation derived earlier by Lewenstein et al. [Phys. Rev. A 51 (1995)\n4617] by means of decoherence and ergodicity arguments. We show analytically\nthat the thermal equilibrium state is a stationary solution of our rate\nequation. We present analytical results for the rate coefficients which are\nneeded to solve the rate equations, and we give approximate formulae that\npermit their computation in practice. We solve the two sets of rate equations\nnumerically and compare the results. The cooling times obtained in both\napproaches agree very well. The equilibration rates show fair agreement."
    },
    {
        "anchor": "Cross-linker mediated compaction and local morphologies in a model\n  chromosome: Chromatin and associated proteins constitute the highly folded structure of\nchromosomes. We consider a self-avoiding polymer model of the chromatin,\nsegments of which may get cross-linked via protein binders that repel each\nother. The binders cluster together via the polymer mediated attraction, in\nturn, folding the polymer. Using molecular dynamics simulations, and a mean\nfield description, we explicitly demonstrate the continuous nature of the\nfolding transition, characterized by unimodal distributions of the polymer size\nacross the transition. At the transition point the chromatin size and\ncross-linker clusters display large fluctuations, and a maximum in their\nnegative cross-correlation, apart from a critical slowing down. Along the\ntransition, we distinguish the local chain morphologies in terms of topological\nloops, inter-loop gaps, and zippering. The topologies are dominated by simply\nconnected loops at the criticality, and by zippering in the folded phase.",
        "positive": "External control strategies for self-propelled particles: optimizing\n  navigational efficiency in the presence of limited resources: We experimentally and numerically study the dependence of different\nnavigation strategies regarding the effectivity of an active particle to reach\na predefined target area. As the only control parameter, we vary the particle's\npropulsion velocity depending on its position and orientation relative to the\ntarget site. By introducing different figures of merit, e.g. the time to target\nor the total consumed propulsion energy, we are able to quantify and compare\nthe efficiency of different strategies. Our results suggest, that each strategy\nto navigate towards a target, has its strengths and weaknesses and none of them\noutperforms the other in all regards. Accordingly, the choice of an ideal\nnavigation strategy will strongly depend on the specific conditions and the\nfigure of merit which should be optimized."
    },
    {
        "anchor": "A comprehensive continuum theory of structured liquids: We develop a comprehensive continuum model capable of treating both\nelectrostatic and structural interactions in liquid dielectrics. Starting from\na two-order parameter description in terms of charge density and polarization,\nwe derive a field-theoretic model generalizing previous theories. Our theory\nexplicitly includes electrostatic and structural interactions in the bulk of\nthe liquid and allows for polarization charges within a Drude model. In\nparticular, we develop a detailed description of the boundary conditions which\ninclude the charge regulation mechanism and surface polarization. The general\nfeatures for solving the saddle-point equations of our model are elucidated and\nfuture applications to predict and validate experimental results are outlined.",
        "positive": "Multiparticle collision dynamics for fluid interfaces with near-contact\n  interactions: We present an extension of the multiparticle collision dynamics method for\nflows with complex interfaces, including supramolecular near-contact\ninteractions mimicking the effect of surfactants. The new method is\ndemonstrated for the case of (i) short range repulsion of droplets in close\ncontact, (ii) arrested phase separation and (iii) different pattern formation\nduring spinodal decomposition of binary mixtures."
    },
    {
        "anchor": "Dynamics of polydisperse multiple emulsions in microfluidic channels: Multiple emulsions are a class of soft fluid in which small drops are\nimmersed within a larger one and stabilized over long periods of time by a\nsurfactant. We recently showed that, if a monodisperse multiple emulsion is\nsubject to a pressure-driven flow, a wide variety of nonequilibrium steady\nstates emerges at late times, whose dynamics relies on a complex interplay\nbetween hydrodynamic interactions and multibody collisions among internal\ndrops. In this work, we use lattice Boltzmann simulations to study the dynamics\nof polydisperse double emulsions driven by a Poiseuille flow within a\nmicrofluidic channel. Our results show that their behavior is critically\naffected by multiple factors, such as initial position, polydispersity index,\nand area fraction occupied within the emulsion. While at low area fraction\ninner drops may exhibit either a periodic rotational motion (at low\npolydispersity) or arrange into nonmotile configurations (at high\npolydispersity) located far from each other, at larger values of area fraction\nthey remain in tight contact and move unidirectionally. This decisively\nconditions their close-range dynamics, quantitatively assessed through a\ntime-efficiency-like factor. Simulations also unveil the key role played by the\ncapsule, whose shape changes can favor the formation of a selected number of\nnonequilibrium states in which both motile and nonmotile configurations are\nfound.",
        "positive": "Doxorubicin Loaded Magnetic Polymersomes: Theranostic Nanocarriers for\n  MR Imaging and Magneto-Chemotherapy: Hydrophobically modified magnetic nanoparticles (MNPs) were encapsulated\nwithin the membrane of poly(trimethylene carbonate)-b-poly(L-glutamic acid)\n(PTMC-b-PGA) block copolymer vesicles using a nanoprecipitation process. This\nformulation method provides a high loading of MNPs (up to 70 wt %) together\nwith a good control over the sizes of the vesicles (100 - 400 nm). The\ndeformation of the vesicle membrane under an applied magnetic field was\nevidenced by anisotropic SANS. These hybrid objects display contrast\nenhancement properties in Magnetic Resonance Imaging, a diagnostic method\nroutinely used for three-dimensional and non-invasive scans of the human body.\nThey can also be guided in a magnetic field gradient. The feasibility of drug\nrelease triggered by magnetic induction was evidenced using the anticancer drug\ndoxorubicin (DOX), which is co-encapsulated in the membrane. Magnetic\npolymersomes are thus proposed as multimodal drug nanocarriers for bio-imaging\nand magneto-chemotherapy."
    },
    {
        "anchor": "Stability of growing vesicles: We investigate the stability of growing vesicles using the formalism of\nnonequilibrium thermodynamics. The vesicles are growing due to the accretion of\nlipids to the bilayer which forms the vesicle membrane. The thermodynamic\ndescription is based on the hydrodynamics of a water{/}lipid mixture together\nwith a model of the vesicle as a discontinuous system in the sense of linear\nnonequilibrium thermodynamics. This formulation allows the forces and fluxes\nrelevant to the dynamic stability of the vesicle to be identified. The method\nis used to analyze the stability of a spherical vesicle against arbitrary\naxisymmetric perturbations. It is found that there are generically two critical\nradii at which changes of stability occur. In the case where the perturbation\ntakes the form of a single zonal harmonic, only one of these radii is physical\nand is given by the ratio $2 L_p / L_\\gamma$, where $L_p$ is the hydraulic\nconductivity and $L_\\gamma$ is the Onsager coefficient related to changes in\nmembrane area due to lipid accretion. The stability of such perturbations is\nrelated to the value of $l$ corresponding to the particular zonal harmonic:\nthose with lower $l$ are more unstable than those with higher $l$. Possible\nextensions of the current work and the need for experimental input are\ndiscussed.",
        "positive": "Coarse-graining dynamics for convection-diffusion of colloids: Taylor\n  dispersion: By applying a hybrid Molecular dynamics and mesoscopic simulation technique,\nwe study the classic convection-diffusion problem of Taylor dispersion for\ncolloidal discs in confined flow. We carefully consider the time and\nlength-scales of the underlying colloidal system. These are, by computational\nnecessity, altered in the coarse-grained simulation method, but as long as this\nis carefully managed, the underlying physics can be correctly interpreted. We\nfind that when the disc diameter becomes non-negligible compared to the\ndiameter of the pipe, there are important corrections to the original Taylor\npicture. For example, the colloids can flow more rapidly than the underlying\nfluid, and their Taylor dispersion coefficient is decreased. The long-time\ntails in the velocity autocorrelation functions are altered by the Poiseuille\nflow. Some of the conclusions about coarse-graining the dynamics of colloidal\nsuspensions are relevant for a wider range of complex fluids."
    },
    {
        "anchor": "Optimal Locomotion for Limbless Crawlers: Limbless crawling is ubiquitous in biology, from cells to organisms. We\ndevelop and analyze a model for the dynamics of one-dimensional elastic\ncrawlers, subject to active stress and deformation-dependent friction with the\nsubstrate. We find that the optimal active stress distribution that maximizes\nthe crawler's center of mass displacement given a fixed amount of energy input\nis a traveling wave. This theoretical optimum corresponds to peristalsis-like\nextension-contraction waves observed in biological organisms, possibly\nexplaining the prevalence of peristalsis as a convergent gait across species.\nOur theory elucidates key observations in biological systems connecting the\nanchoring phase of a crawler to the retrograde and prograde distinction seen in\nperistaltic waves among various organisms. Using our optimal gait solution, we\nderive a scaling relation between the crawling speed and body mass, explaining\nexperiments on earthworms with three orders of magnitude body mass variations.\nOur results offer insights and tools for optimal bioinspired crawling robots\ndesign with finite battery capacity.",
        "positive": "New Insight Into the Size Tuning of Monodispersed Colloidal Gold\n  Obtained by Citrate Method: We study the effect of citrate to gold molar ratio (X) on the size of\ncitrated gold nanoparticles (AuNPs). This dependence is still a matter of\ndebate for X $\\ge$ 3 where the polydispersity is yet minimized. Indeed, there\nis no consensus between experiments proposed so far for comparable experimental\nconditions. Nonetheless, the sole available theoretical prediction has never\nbeen validated experimentally in this range of X. We show unambiguously using 3\ntechniques (UV-Vis spectroscopy, dynamic light scattering and transmission\nelectronic microscopy), 2 different synthetic approaches (Direct, Inverse) and\n10 X values for each approach that AuNPs' size decay as a monoexponential with\nX. This result is, for the first time, in agreement with the sole available\ntheoretical prediction by Kumar et al. on the whole studied range of X."
    },
    {
        "anchor": "Biomimetic Synchronization in biciliated robots: Direct mechanical coupling is known to be critical for establishing\nsynchronization among cilia. However, the actual role of the connections is\nstill elusive - partly because controlled experiments in live samples are\nchallenging. Here, we employ an artificial ciliary system to address this\nissue. Two cilia are formed by chains of self-propelling robots and anchored to\na shared base so that they are purely mechanically-coupled. The system mimics\nbiological ciliary beating but allows fine control over the beating dynamics.\nWe find that the artificial cilia exhibit rich motion behaviors, depending on\nthe mechanical coupling scheme. Particularly, their synchronous beating display\ntwo distinct modes - analogous to those observed in C. reinhardtii, the\nbiciliated model organism for studying synchronization. Close examination\nsuggests that the system evolves towards the most dissipative mode. Using this\nguideline in both simulations and experiments, we are able to direct the system\ninto a desired state by altering the modes' respective dissipation. Our results\nhave significant implications in understanding the synchronization of cilia.",
        "positive": "Forming Long-range Order of Semiconducting Polymers through Liquid-phase\n  Directional Molecular Assemblies: Intermolecular interactions are crucial in determining the morphology of\nsolution-processed semiconducting polymer thin films. However, these random\ninteractions often lead to disordered or short-range ordered structures.\nAchieving long-range order in these films has been a challenge due to limited\ncontrol over microscopic interactions in current techniques. Here, we present a\nmolecular-level methodology that leverages spatial matching of intermolecular\ndynamics among solutes, solvents, and substrates to induce directional\nmolecular assembly in weakly bonded polymers. Within the optimized dynamic\nscale of 2.5 \\r{A} between polymer side chains and self-assembled monolayers\n(SAMs) on nanogrooved substrates, our approach transforms random aggregates\ninto unidirectional fibers with a remarkable increase in the anisotropic\nstacking ratio from 1 to 11. The Flory-Huggins-based molecular stacking model\naccurately predicts the transitioning order on various SAMs, validated by\nmorphologic and spectroscopic observations. The enhanced structural ordering\nspans over 3 orders of magnitude in length, raising from the smallest 7.3 nm\nrandom crystallites to >14 um unidirectional fibers on sub-millimeter areas.\nOverall, this study provides insights into the control of complex\nintermolecular interactions and offers enhanced molecular-level controllability\nin solution-based processes."
    },
    {
        "anchor": "Effects of polymer concentration and chain length on aggregation in\n  physically associating polymer solutions: The effects of polymer concentration and chain length on aggregation in\nassociative polymer solutions, are studied using self-consistent field lattice\nmodel. Only two inhomogenous morphologies, i.e. microfluctuation homogenous\n(MFH) and micelle morphologies, are observed in the systems with different\nchain lengths. The temperatures at which the above two inhomogenous\nmorphologies first appear, which are denoted by T_MFH and T_m, respectively,\nare dependent on polymer concentration and chain length. The variation of the\nlogarithm of critical MFH concentration with the logarithm of chain length\nfulfils a linear-fitting relationship with a slope equaling -1. Furthermore,\nthe variation of the average volume fraction of stickers at the micellar core\n(AVFSM) with polymer concentration and chain length is focused in the system at\nT_m. It is founded by calculations that the above behavior of AVFSM, is\nexplained in terms of intrachain and interchain associations.",
        "positive": "Shear viscosity of pseudo hard-spheres: We present molecular dynamics simulations of pseudo hard sphere fluid\n(generalized WCA potential with exponents (50, 49) proposed by Jover et al. J.\nChem. Phys 137, (2012)) using GROMACS package. The equation of state and radial\ndistribution functions at contact are obtained from simulations and compared to\nthe available theory of true hard spheres (HS) and available data on pseudo\nhard spheres. The comparison shows agreements with data by Jover et al. and the\nCarnahan-Starling equation of HS. The shear viscosity is obtained from the\nsimulations and compared to the Enskog expression and previous HS simulations.\nIt is demonstrated that the PHS potential reproduces the HS shear viscosity\naccurately."
    },
    {
        "anchor": "Nonequilibrium dynamical structure of a dilute suspension of active\n  particles in a viscoelastic fluid: In this work, we investigate the dynamics of the number density fluctuations\nof a dilute suspension of active particles in a linear viscoelastic fluid. We\npropose a model for the frequency-dependent diffusion coefficient of the active\nparticles, which captures the effect of rotational diffusion on the persistence\nof their self-propelled motion and the viscoelasticity of the medium. Using\nfluctuating hydrodynamics, the linearized equations for the active suspension\nare derived, from which we calculate its dynamic structure factor and the\ncorresponding intermediate scattering function. For a Maxwell-type rheological\nmodel, we find an intricate dependence of these functions on the parameters\nthat characterize the viscoelasticity of the solvent and the activity of the\nparticles, which can significantly deviate from those of an inert suspension of\npassive particles and of an active suspension in a Newtonian solvent. In\nparticular, in some regions of the parameter space we uncover the emergence of\noscillations in the intermediate scattering function at certain wave numbers,\nwhich represent the hallmark of the non-equilibrium particle activity in the\ndynamical structure of the suspension and also encode the viscoelastic\nproperties of the medium.",
        "positive": "Modeling intermolecular and intramolecular modes of liquid water using\n  multiple heat baths: Machine learning approach: The vibrational motion of molecules in dissipative environments, such as\nsolvation and protein molecules, is composed of contributions from both\nintermolecular and intramolecular modes. The existence of these collective\nmodes introduces difficulty into quantum simulations of chemical and biological\nprocesses. In order to describe the complex molecular motion of the environment\nin a simple manner, we introduce a system-bath model in which the\nintramolecular modes with anharmonic mode-mode couplings are described by a\nsystem Hamiltonian, while the other degrees of freedom, arising from the\nenvironmental molecules, are described by heat bath. Employing a\nmachine-learning based approach, we determine not only the system parameters of\nthe intramolecular modes but also the spectral distribution of the system-bath\ncoupling to describe the intermolecular modes, using the atomic trajectories\nobtained from molecular dynamics (MD) simulations. The capabilities of the\npresent approach are demonstrated for liquid water using MD trajectories\ncalculated from the SPC/E model and the polarizable water model for\nintramolecular and intermolecular vibrational spectroscopies (POLI2VS) by\ndetermining the system parameters describing the symmetric-stretch,\nasymmetric-stretch and bend modes with intramolecular interactions and the bath\nspectral distribution functions for each intramolecular mode representing the\ninteraction with the intra-molecular modes. From these results, we were able to\nelucidate the energy relaxation pathway between the intramolecular modes and\nthe intermolecular modes in a non-intuitive manner."
    },
    {
        "anchor": "Phase separation of a magnetic fluid: Asymptotic states and\n  non-equilibrium kinetics: We study self-assembly in a colloidal suspension of magnetic particles by\nperforming comprehensive molecular dynamics simulations of the Stockmayer (SM)\nmodel which comprises spherical particles decorated by a magnetic moment. The\nSM potential incorporates dipole-dipole interactions along with the usual\nLennard-Jones interaction and exhibits a gas-liquid phase coexistence observed\nexperimentally in magnetic fluids. When this system is quenched from the\nhigh-temperature homogeneous phase to the coexistence region, the\nnon-equilibrium evolution to the condensed phase proceeds with the development\nof spatial as well as magnetic order. We observe density-dependent coarsening\nmechanisms - a diffusive growth law $\\ell(t)\\sim t^{1/3}$ in the nucleation\nregime, and hydrodynamics-driven inertial growth law $\\ell(t)\\sim t^{2/3}$ in\nthe spinodal regimes. [$\\ell(t)$ is the average size of the condensate at time\n$t$ after the quench.] While the spatial growth is governed by the expected\nconserved order parameter dynamics, the growth of magnetic order in the\nspinodal regime exhibits unexpected non-conserved dynamics. The asymptotic\nmorphologies have density-dependent shapes which typically include the\nisotropic sphere and spherical bubble morphologies in the nucleation region,\nand the anisotropic cylinder, planar slab, cylindrical bubble morphologies in\nthe spinodal region. The structures are robust and nonvolatile and exhibit\ncharacteristic magnetic properties. For example, the oppositely magnetized\nhemispheres in the spherical morphology impart the characteristics of a {\\it\nJanus particle} to it. The observed structures have versatile applications in\ncatalysis, drug delivery systems, memory devices, and magnetic photonic\ncrystals, to name a few.",
        "positive": "Numerical Study of the Correspondence Between the Dissipative and Fixed\n  Energy Abelian Sandpile Models: We consider the Abelian sandpile model (ASM) on the large square lattice with\na single dissipative site (sink). Particles are added by one per unit time at\nrandom sites and the resulting density of particles is calculated as a function\nof time. We observe different scenarios of evolution depending on the value of\ninitial uniform density (height) $h_0=0,1,2,3$. During the first stage of the\nevolution, the density of particles increases linearly. Reaching a critical\ndensity $\\rho_c(h_0)$, the system changes its behavior sharply and relaxes\nexponentially to the stationary state of the ASM with $\\rho_s=25/8$. We found\nnumerically that $\\rho_c(0)=\\rho_s$ and $\\rho_c(h_0>0) \\neq \\rho_s$. Our\nobservations suggest that the equality $\\rho_c=\\rho_s$ holds for more general\ninitial conditions with non-positive heights. In parallel with the ASM, we\nconsider the conservative fixed-energy Abelian sandpile model (FES). The\nextensive Monte-Carlo simulations for $h_0=0,1,2,3$ have confirmed that in the\nlimit of large lattices $\\rho_c(h_0)$ coincides with the threshold density\n$\\rho_{th}(h_0)$ of FES. Therefore, $\\rho_{th}(h_0)$ can be identified with\n$\\rho_s$ if the FES starts its evolution with non-positive uniform height $h_0\n\\leq 0$."
    },
    {
        "anchor": "General model of phospholipid bilayers in fluid phase within the single\n  chain mean field theory: Coarse-grained model for saturated (DCPC, DLPC, DMPC, DPPC, DSPC) and\nunsaturated (POPC, DOPC) phospholipids is introduced within the Single Chain\nMean Field theory. A single set of parameters adjusted for DMPC bilayers gives\nan adequate description of equilibrium and mechanical properties of a range of\nsaturated lipid molecules that differ only in length of their hydrophobic tails\nand unsaturated (POPC, DOPC) phospholipids which have double bonds in the\ntails. A double bond is modeled with a fixed angle of 120 degrees, while the\nrest of the parameters are kept the same as saturated lipids. The thickness of\nthe bilayer and its hydrophobic core, the compressibility and the equilibrium\narea per lipid correspond to experimentally measured values for each lipid,\nchanging linearly with the length of the tail. The model for unsaturated\nphospholipids also fetches main thermodynamical properties of the bilayers.\nThis model is used for an accurate estimation of the free energies of the\ncompressed or stretched bilayers in stacks or multilayers and gives reasonable\nestimates for free energies. The proposed model may further be used for studies\nof mixtures of lipids, small molecule inclusions, interactions of bilayers with\nembedded proteins.",
        "positive": "DNA electrophoresis in designed channels: We present a simple description on the electrophoretic dynamics of\npolyelectrolytes going through designed channels with narrow constrictions of\nslit geometry. By analyzing rheological behaviours of the stuck chain, which is\ncoupled to the effect of solvent flow, three critical electric fields\n(permeation field $E^{(per)} \\sim N^{-1}$, deformation field $E^{(def)} \\sim\nN^{-3/5}$ and injection field $E^{(inj)} \\simeq N^0$, with $N$ polymerization\nindex) are clarified. Between $E^{(per)}$ and $E^{(inj)}$, the chain migration\nis dictated by the driven activation process. In particular, at $E>E^{(def)}$,\nthe stuck chain at the slit entrance is strongly deformed, which enhances the\nrate of the permeation. From these observations, electrophoretic mobility at a\ngiven electric field is deduced, which shows non-monotonic dependence on $N$.\nFor long enough chains, mobility increases with $N$, in good agreement with\nexperiments. An abrupt change in the electrophoretic flow at a threshold\nelectric field is formally regarded as a nonequilibrium phase transition."
    },
    {
        "anchor": "Fully developed and transient concentration profiles of particulate\n  suspensions sheared in a cylindrical Couette: We experimentally investigate particle migration in a non-Brownian suspension\nsheared in a Taylor-Couette configuration and in the limit of vanishing\nReynolds number. Highly resolved index-matching techniques are used to measure\nthe local particulate volume fraction. In this wide-gap Taylor-Couette\nconfiguration, we find that for a large range of bulk volume fraction, $\\phi_b\n\\in [20\\% - 50\\%]$, the fully developed concentration profiles are well\npredicted by the suspension balance model of Nott \\& Brady (J. Fluid Mech.,\nvol. 275, 1994, pp. 157-199). Moreover, we provide systematic measurements of\nthe migration strain scale and of the migration amplitude which highlight the\nlimits of the suspension balance model predictions.",
        "positive": "Fibril elongation mechanisms of HET-s prion-forming domain: Topological\n  evidence for growth polarity: The prion-forming C-terminal domain of the fungal prion HET-s forms\ninfectious amyloid fibrils at physiological pH. The conformational switch from\nthe non-prion soluble form to the prion fibrillar form is believed to have a\nfunctional role, since HET-s in its prion form participates in a recognition\nprocess of different fungal strains. Based on the knowledge of the\nhigh-resolution structure of HET-s(218-289) (the prion forming-domain) in its\nfibrillar form, we here present a numerical simulation of the fibril growth\nprocess which emphasizes the role of the topological properties of the\nfibrillar structure. An accurate thermodynamic analysis of the way an\nintervening HET-s chain is recruited to the tip of the growing fibril suggests\nthat elongation proceeds through a dock and lock mechanism. First, the chain\ndocks onto the fibril by forming the longest $\\beta$-strands. Then, the\nre-arrangement in the fibrillar form of all the rest of molecule takes place.\nInterestingly, we predict also that one side of the HET-s fibril is more\nsuitable for substaining its growth with respect to the other. The resulting\nstrong polarity of fibril growth is a consequence of the complex topology of\nHET-s fibrillar structure, since the central loop of the intervening chain\nplays a crucially different role in favouring or not the attachment of the\nC-terminus tail to the fibril, depending on the growth side."
    },
    {
        "anchor": "The vanishing water/oil interface in the presence of antagonistic salt: Antagonistic salts are salts which consist of hydrophilic and hydrophobic\nions. In a binary mixture of water and organic solvent, these ions\npreferentially dissolve into different phases. We investigate the effect of an\nantagonistic salt, tetraphenylphosphonium chloride PPh$_4$Cl, in a mixture of\nwater and 2,6-lutidine by means of Molecular Dynamics (MD) Simulations. For\nincreasing concentrations of the salt the two-phase region is shrunk and the\ninterfacial tension in reduced, in contrast to what happens when a normal salt\nis added to such a mixture. The MD simulations allow us to investigate in\ndetail the mechanism behind the reduction of the surface tension. We obtain the\nion and composition distributions around the interface and determine the\nhydrogen bonds in the system and conclude that the addition of salt alter the\nhydrogen bonding.",
        "positive": "Steady-State Homogeneous Nucleation and Growth of Water Droplets:\n  Extended Numerical Treatment: The steady-state homogeneous vapor-to-liquid nucleation and the succeeding\nliquid droplet growth process are studied for water system by means of the\ncoarse-grained molecular dynamics simulations with the mW-model suggested\noriginally in [Molinero, V.; Moore, E. B. \\textit{J. Phys. Chem. B}\n\\textbf{2009}, \\textit{113}, 4008-4016]. The investigation covers the\ntemperature range $273 \\leq T/K \\leq 363$ and the system's pressure $p\\simeq 1$\natm. The thermodynamic integration scheme and the extended mean first passage\ntime method as a tool to find the nucleation and cluster growth characteristics\nare applied. The surface tension is numerically estimated and is compared with\nthe experimental data for the considered temperature range. We extract the\nnucleation characteristics such as the steady-state nucleation rate, the\ncritical cluster size, the nucleation barrier, the Zeldovich factor; perform\nthe comparison with the other simulation results and test the treatment of the\nsimulation results within the classical nucleation theory. We found that the\nliquid droplet growth is unsteady and follows the power law. At that, the\ngrowth laws exhibit the features unified for all the considered temperatures.\nThe geometry of the nucleated droplets is also studied."
    },
    {
        "anchor": "A computational study of chemically heterogeneous particles: patchy vs.\n  uniform particles in shear flow: The adhesion of flowing particles and biological cells over fixed collecting\nsurfaces is vitally important in diverse situations and potentially controlled\nby small-scale surface heterogeneity on the particle. Differences in the\nbehavior of patchy particles (flowing over uniform collectors) relative to the\nreverse case of uniform particles (flowing over patchy collectors) are\nquantified. Because a particle rotates more slowly than it translates in the\nshear field near a collecting surface, the effective interaction time of a\npatch on a particle is larger than that of a patch on the collector, suggesting\ndistinct particle capture tendencies in each case. This paper presents a new\ncomputational approach to simulate the near-surface motion (rotation and\ntranslation) of particles having nanoscale surface heterogeneities flowing over\nuniform collectors. Small amounts of ~10 nm cationic patches randomly\ndistributed on a net-negative particle surface produced spatially varying DLVO\ninteractions that were computed via the Grid Surface Integration (GSI)\ntechnique and then combined with hydrodynamic forces in a mobility tensor\nformulation. Statistical analysis of simulated trajectories revealed fewer\nextrema in the fluctuating particle-collector separation of heterogeneous\nparticles, compared with the reverse system geometry of uniform particles\nflowing past a heterogeneous fixed surface. Additionally, the patchy particles\nwere captured to a lesser extent on uniform surfaces compared with the case of\nuniform particles flowing above patchy collectors. Such behavior was dependent\non ionic strength, with the greatest differences obtained near a Debye length\nof $\\kappa^{-1} = 4$ nm for the $2a = 500$ nm simulated particles.",
        "positive": "Uniform line fillings: Deterministic fabrication of random metamaterials requires filling of a space\nwith randomly oriented and randomly positioned chords with an on-average\nhomogenous density and orientation, which is a nontrivial task. We describe a\nmethod to generate fillings with such chords, lines that run from edge to edge\nof the space, in any dimension. We prove that the method leads to random but\non-average homogeneous and rotationally invariant fillings of circles, balls\nand arbitrary-dimensional hyperballs from which other shapes such as rectangles\nand cuboids can be cut. We briefly sketch the historic context of Bertrand's\nparadox and Jaynes' solution by the principle of maximum ignorance. We analyse\nthe statistical properties of the produced fillings, mapping out the density\nprofile and the line-length distribution and comparing them to analytic\nexpressions. We study the characteristic dimensions of the space in between the\nchords by determining the largest enclosed circles and balls in this pore\nspace, finding a lognormal distribution of the pore sizes. We apply the\nalgorithm to the direct-laser-writing fabrication design of optical\nmultiple-scattering samples as three-dimensional cubes of random but\nhomogeneously positioned and oriented chords."
    },
    {
        "anchor": "Transport of heat and mass in a two-phase mixture. From a continuous to\n  a discontinuous description: We present a theory which describes the transport properties of the\ninterfacial region with respect to heat and mass transfer. Postulating the\nlocal Gibbs relation for a continuous description inside the interfacial\nregion, we derive the description of the Gibbs surface in terms of excess\ndensities and fluxes along the surface. We introduce overall interfacial\nresistances and conductances as the coefficients in the force-flux relations\nfor the Gibbs surface. We derive relations between the local resistivities for\nthe continuous description inside the interfacial region and the overall\nresistances of the surface for transport between the two phases for a mixture.\nIt is shown that interfacial resistances depend among other things on the\nenthalpy profile across the interface. Since this variation is substantial the\ncoupling between heat and mass flow across the surface are also substantial. In\nparticular, the surface puts up much more resistance to the heat and mass\ntransfer then the homogeneous phases over a distance comparable to the\nthickness of the surface. This is the case not only for the pure heat\nconduction and diffusion but also for the cross effects like thermal diffusion.\nFor the excess fluxes along the surface and the corresponding thermodynamic\nforces we derive expressions for excess conductances as integrals over the\nlocal conductivities along the surface. We also show that the curvature of the\nsurface affects only the overall resistances for transport across the surface\nand not the excess conductivities along the surface.",
        "positive": "Molecular Dynamics simulations of Doxorubicin in sphingomyelin-based\n  lipid membranes: Doxorubicin (DOX) is one of the most efficient antitumor drugs employed in\nnumerous cancer therapies. Its incorporation into lipid-based nanocarriers,\nsuch as liposomes, improves the drug targeting into tumor cells and reduces\ndrug side effects. The carriers' lipid composition is expected to affect the\ninteractions of DOX and its partitioning into liposomal membranes. To get a\nrational insight into this aspect and determine promising lipid compositions,\nwe use numerical simulations, which provide unique information on DOX-membrane\ninteractions at the atomic level of resolution. In particular, we combine\nclassical molecular dynamics simulations and free energy calculations to\nelucidate the mechanism of penetration of a protonated Doxorubicin molecule\n(DOX+) into potential liposome membranes, here modeled as lipid bilayers based\non mixtures of phosphatidylcholine (PC), sphingomyelin (SM) and cholesterol\nlipid molecules, of different compositions and lipid phases. Moreover, we\nanalyze DOX+ partitioning into relevant regions of SM-based lipid bilayer\nsystems using a combination of free energy methods. Our results show that DOX+\npenetration and partitioning are facilitated into less tightly packed SM-based\nmembranes and are dependent on lipid composition. This work paves the way to\nfurther investigations of optimal formulations for lipid-based carriers, such\nas those associated with pH-responsive membranes."
    },
    {
        "anchor": "Dewetting-controlled binding of ligands to hydrophobic pockets: We report on a combined atomistic molecular dynamics simulation and implicit\nsolvent analysis of a generic hydrophobic pocket-ligand (host-guest) system.\nThe approaching ligand induces complex wetting/dewetting transitions in the\nweakly solvated pocket. The transitions lead to bimodal solvent fluctuations\nwhich govern magnitude and range of the pocket-ligand attraction. A recently\ndeveloped implicit water model, based on the minimization of a geometric\nfunctional, captures the sensitive aqueous interface response to the\nconcave-convex pocket-ligand configuration semi-quantitatively.",
        "positive": "Simulation of crumpled sheets via alternating quasistatic and dynamic\n  representations: In this work, we present a method for simulating the large-scale deformation\nand crumpling of thin, elastoplastic sheets. Motivated by the physical behavior\nof thin sheets during crumpling, two different formulations of the governing\nequations of motion are used: (1) a quasistatic formulation that effectively\ndescribes smooth deformations, and (2) a fully dynamic formulation that\ncaptures large changes in the sheet's velocity. The former is a\ndifferential-algebraic system of equations integrated implicitly in time, while\nthe latter is a set of ordinary differential equations (ODEs) integrated\nexplicitly. We adopt a hybrid integration scheme to adaptively alternate\nbetween the quasistatic and dynamic representations as appropriate. We\ndemonstrate the capacity of this method to effectively simulate a variety of\ncrumpling phenomena. Finally, we show that statistical properties, notably the\naccumulation of creases under repeated loading, as well as the area\ndistribution of facets, are consistent with experimental observations."
    },
    {
        "anchor": "Metastability of lipid necks via geometric triality: \"Necks\" are features of lipid membranes characterized by an uniquley large\ncurvature, functioning as bridges between different compartments. These\nfeatures are ubiquitous in the life-cycle of the cell and instrumental in\nprocesses such as division, extracellular vesicles uptake and cargo transport\nbetween organelles, but also in life-threatening conditions, as in the\nendocytosis of viruses and phages. Yet, the very existence of lipid necks\nchallenges our understanding of membranes biophysics: their curvature, often\norders of magnitude larger than elsewhere, is energetically prohibitive, even\nwith the arsenal of molecular machineries and signalling pathways that cells\nhave at their disposal. Using a geometric triality, namely a correspondence\nbetween three different classes of geometric objects, here we demonstrate that\nlipid necks are in fact metastable, thus can exist for finite, but potentially\nlong times even in the absence of stabilizing mechanisms. This framework allows\nus to explicitly calculate the forces a corpuscle must overcome in order to\npenetrate cellular membranes, thus paving the way for a predictive theory of\nendo/exo-cytic processes.",
        "positive": "Coarsening transitions of wet liquid foams under microgravity conditions: We report foam coarsening studies which were performed in the International\nSpace Station (ISS) to suppress drainage due to gravity. Foams and bubbly\nliquids with controlled liquid fractions $\\phi$ between 15 and 50\\% were\ninvestigated to study the transition between bubble growth laws previously\nreported near the dry limit $\\phi \\rightarrow 0$ and the dilute limit $\\phi\n\\rightarrow 1$ (Ostwald ripening). We determined the coarsening rates; for the\ndriest foams and the bubbly liquids, they are in close agreement with\ntheoretical predictions. We observe a sharp cross-over between the respective\nlaws at a critical value $\\phi^*$. At liquid fractions beyond this transition,\nneighboring bubbles are no longer all in contact, like at a jamming transition.\nRemarkably $\\phi^*$ is significantly larger than the random close packing\nvolume fraction of the bubbles $\\phi_{\\text{rcp}}$ which was determined\nindependently. We attribute the differences between $\\phi^*$ and\n$\\phi_{\\text{rcp}}$ to a weakly adhesive bubble interaction that we have\nstudied in complementary ground-based experiments."
    },
    {
        "anchor": "Microdomains and Stress Distributions in Bacterial Monolayers on Curved\n  Interfaces: Monolayers of growing non-motile rod-shaped bacteria act as active nematic\nmaterials composed of hard particles rather than the flexible components of\nother commonly studied active nematics. The organization of these granular\nmonolayers has been studied on flat surfaces but not on curved surfaces, which\nare known to change the behavior of other active nematics. We use molecular\ndynamics simulations to track alignment and stress in growing monolayers fixed\nto curved surfaces, and investigate how these vary with changing surface\ncurvature and cell aspect ratio. We find that the length scale of alignment\n(measured by average microdomain size) increases with cell aspect ratio and\ndecreases with curvature. Additionally, we find that alignment controls the\ndistribution of extensile stresses in the monolayer by concentrating stress in\nlow-order regions. These results connect active nematic physics to bacterial\nmonolayers and can be applied to model bacteria growing on droplets, such as\nmarine oil-degrading bacteria.",
        "positive": "Structure and Dynamics of the Quasi-Liquid Layer at the Surface of Ice\n  from Molecular Simulations: We characterized the structural and dynamical properties of the quasi-liquid\nlayer (QLL) at the surface of ice by molecular dynamics simulations with a\nthermodynamically consistent water model. Our simulations show that for three\nlow-index ice surfaces only the outermost molecular layer presents short-range\nand mid-range disorder and is diffusive. The onset temperature for normal\ndiffusion is much higher than the glass temperature of supercooled water,\nalthough the diffusivity of the QLL is higher than that of bulk water at the\ncorresponding temperature. The underlying subsurface layers impose an ordered\ntemplate, which produces a regular patterning of the ice/water interface at any\ntemperature, and is responsible for the major differences between QLL and bulk\nwater, especially for what concern the dynamics and the mid-range structure of\nthe hydrogen-bonded network. Our work highlights the need of a holistic\napproach to the characterization of QLL, as a single experimental technique may\nprobe only one specific feature, missing part of the complexity of this\nfascinating system."
    },
    {
        "anchor": "Turbulent heat transport near critical points: Non-Boussinesq effects: This paper has been withdrawn",
        "positive": "Well-posed continuum equations for granular flow with compressibility\n  and $\u03bc(I)$-rheology: Continuum modelling of granular flow has been plagued with the issue of\nill-posed equations for a long time. Equations for incompressible,\ntwo-dimensional flow based on the Coulomb friction law are ill-posed regardless\nof the deformation, whereas the rate-dependent $\\mu(I)$-rheology is ill-posed\nwhen the non-dimensional strain-rate $I$ is too high or too low. Here,\nincorporating ideas from Critical-State Soil Mechanics, we derive conditions\nfor well-posedness of PDEs that combine compressibility with $I$-dependent\nrheology. When the $I$-dependence comes from a specific friction coefficient\n$\\mu(I)$, our results show that, with compressibility, the equations are\nwell-posed for all deformation rates provided that $\\mu(I)$ satisfies certain\nminimal, physically natural, inequalities."
    },
    {
        "anchor": "Size-Sieving Separation of Hard-Sphere Mixtures through Cylindrical\n  Pores: The collision dynamics of hard spheres and cylindrical pores is solved\nexactly, which is the minimal model for a regularly porous membrane.\n  Nonequilibrium event-driven molecular dynamics simulations are used to show\nthat the permeability $P$ of hard spheres of size $\\sigma$ through cylinderical\npores of size $d$ follow the hindered diffusion mechanism due to size exclusion\nas $P \\propto (1-\\sigma/d)^2$. Under this law, the separation of binary\nmixtures of large and small particles exhibits a linear relationship between\n$\\alpha^{-1/2}$ and $P^{-1/2}$, where $\\alpha$ and $P$ are the selectivity and\npermeability of the smaller particle, respectively. The mean permeability\nthrough polydisperse pores is the sum of permeabilities of individual pores,\nweighted by the fraction of the single pore area over the total pore area.",
        "positive": "Unified analytic expressions for the entanglement length, tube diameter,\n  and plateau modulus of polymer melts: By combining molecular dynamics simulations and topological analyses with\nscaling arguments, we obtain analytic expressions that quantitatively predict\nthe entanglement length $N_e$, the plateau modulus $G$, and the tube diameter\n$a$ in melts that span the entire range of chain stiffnesses for which systems\nremain isotropic. Our expressions resolve conflicts between previous scaling\npredictions for the loosely entangled [Lin-Noolandi: $G\\ell_K^3/k_\\textrm{B}T\n\\sim (\\ell_K/p)^3$], semiflexible [Edwards/de Gennes: $G\\ell_K^3/k_\\textrm{B}T\n\\sim (\\ell_K/p)^2$], and tightly-entangled [Morse: $G\\ell_K^3/k_\\textrm{B}T\n\\sim (\\ell_K/p)^{1+\\epsilon}$] regimes, where $\\ell_K$ and $p$ are respectively\nthe Kuhn and packing lengths. We also find that maximal entanglement (minimal\n$N_e$) coincides with the onset of local nematic order."
    },
    {
        "anchor": "Creep motion in a granular pile exhibiting steady surface flow: We investigate experimentally granular piles exhibiting steady surface flow.\nBelow the surface flow, it has been believed exisitence of a `frozen' bulk\nregion, but our results show absence of such a frozen bulk. We report here that\neven the particles in deep layers in the bulk exhibit very slow flow and that\nsuch motion can be detected at an arbitrary depth. The mean velocity of the\ncreep motion decays exponentially with depth, and the characteristic decay\nlength is approximately equal to the particle-size and independent of the flow\nrate. It is expected that the creep motion we have seeen is observable in all\nsheared granular systems.",
        "positive": "Polymorphism, thermodynamic anomalies and network formation in an\n  atomistic model with two internal states: Using molecular dynamics simulations we study the temperature-density phase\ndiagram of a simple model system of particles in two dimensions. In addition to\ntranslational degrees of freedom, each particle has two internal states and\ninteracts with a modified Lennard-Jones potential which depends on relative\npositions as well as the internal states. We find that, despite its simplicity,\nthe model has a rich phase diagram showing many features of common\nnetwork-forming liquids such as water and silica, including polymorphism and\nthermodynamic anomalies. We believe our model may be useful for studies\nconcerning generic features of such complex liquids."
    },
    {
        "anchor": "The nonlinear elastic response of bicontinuous rubber blends: Rubber blends are ubiquitous in countless technological applications. More\noften than not, rubber blends exhibit complex interpenetrating microstructures,\nwhich are thought to have a significant impact on their resulting macroscopic\nmechanical properties. As a first step to understand this potential impact,\nthis paper presents a bottom-up or homogenization study of the nonlinear\nelastic response of the prominent class of bicontinuous rubber blends, that is,\nblends made of two immiscible constituents or phases segregated into an\ninterpenetrating network of two separate but fully continuous domains that are\nperfectly bonded to one another. The focus is on blends that are isotropic and\nthat contain an equal volume fraction (50/50) of each phase. The\nmicrostructures of these blends are idealized as microstructures generated by\nlevel cuts of Gaussian random fields that are suitably constrained to be\nperiodic so as to allow for the construction of unit cells over which periodic\nhomogenization can be carried out. The homogenized or macroscopic elastic\nresponse of such blends are determined both numerically via finite elements and\nanalytically via a nonlinear comparison medium method. The numerical approach\nmakes use of a novel meshing scheme that leads to conforming and periodic\nsimplicial meshes starting from a voxelized representation of the\nmicrostructures. Results are presented for the fundamental case when both\nrubber phases are Neo-Hookean, as well as when they exhibit non-Gaussian\nelasticity. Remarkably, irrespective of the elastic behavior of the phases, the\nresults show that the homogenized response of the blends is largely insensitive\nto the specific morphologies of the phases.",
        "positive": "Confined water in the low hydration regime: Molecular dynamics results on water confined in a silica pore in the low\nhydration regime are presented. Strong layering effects are found due to the\nhydrophilic character of the substrate. The local properties of water are\nstudied as function of both temperature and hydration level. The interaction of\nthe thin films of water with the silica atoms induces a strong distortion of\nthe hydrogen bond network. The residence time of the water molecules is\ndependent on the distance from the surface. Its behavior shows a transition\nfrom a brownian to a non-brownian regime approaching the substrate in agreement\nwith results found in studies of water at contact with globular proteins."
    },
    {
        "anchor": "Reentrant Rigidity Percolation in Structurally Correlated Filamentous\n  Networks: Many biological tissues feature a heterogeneous network of fibers whose\ntensile and bending rigidity contribute substantially to these tissues' elastic\nproperties. Rigidity percolation has emerged as a important paradigm for\nrelating these filamentous tissues' mechanics to the concentrations of their\nconstituents. Past studies have generally considered tuning of networks by\nspatially homogeneous variation in concentration, while ignoring structural\ncorrelation. We here introduce a model in which dilute fiber networks are built\nin a correlated manner that produces alternating sparse and dense regions. Our\nsimulations indicate that structural correlation consistently allows tissues to\nattain rigidity with less material. We further find that the percolation\nthreshold varies non-monotonically with the degree of correlation, such that it\ndecreases with moderate correlation and once more increases for high\ncorrelation. We explain the eventual reentrance in the dependence of the\nrigidity percolation threshold on correlation as the consequence of large,\nstiff clusters that are too poorly coupled to transmit forces across the\nnetwork. Our study offers deeper understanding of how spatial heterogeneity may\nenable tissues to robustly adapt to different mechanical contexts.",
        "positive": "Phase diagram of patchy colloids: towards empty liquids: We report theoretical and numerical evaluations of the phase diagram for\npatchy colloidal particles of new generation. We show that the reduction of the\nnumber of bonded nearest neighbours offers the possibility of generating liquid\nstates (i.e. states with temperature $T$ lower than the liquid-gas critical\ntemperature) with a vanishing occupied packing fraction ($\\phi$), a case which\ncan not be realized with spherically interacting particles. Theoretical results\nsuggest that such reduction is accompanied by an increase of the region of\nstability of the liquid phase in the ($T$-$\\phi$) plane, possibly favoring the\nestablishment of homogeneous disordered materials at small $\\phi$, i.e. stable\nequilibrium gels."
    },
    {
        "anchor": "Spontaneous motion of a droplet coupled with a chemical wave: We propose a novel framework for the spontaneous motion of a droplet coupled\nwith internal dynamic patterns generated in a reaction-diffusion system. The\nspatio-temporal order of the chemical reaction gives rise to inhomogeneous\nsurface tension and results in self-propulsion driven by the surrounding flow\ndue to the Marangoni effect. Numerical calculations of internal patterns\ntogether with theoretical results of the flow fields at low Reynolds number\nwell reproduces the experimental results obtained using a droplet of\nBelousov-Zhabotinsky (BZ) reaction medium.",
        "positive": "Rare-event trajectory ensemble analysis reveals metastable dynamical\n  phases in lattice proteins: We explore the dynamical large-deviations of a lattice heteropolymer model of\na protein by means of path sampling of trajectories. We uncover the existence\nof non-equilibrium dynamical phase-transitions in ensembles of trajectories\nbetween active and inactive dynamical phases, whose nature depends on\nproperties of the interaction potential. When the full heterogeneity of\ninteractions due to the amino-acid sequence is preserved, as in a fully\ninteracting model or in a heterogeneous version of the G\\={o} model where only\nnative interactions are considered, the transition is between the equilibrium\nnative state and a highly native but kinetically trapped state. In contrast,\nfor the homogeneous G\\={o} model, where there is a single native energy and the\nsequence plays no role, the dynamical transition is a direct consequence of the\nstatic bi-stability between unfolded and native states. In the heterogeneous\ncase the native-active and native-inactive states, despite their static\nsimilarity, have widely varying dynamical properties, and the transition\nbetween them occurs even in lattice proteins whose sequences are designed to\nmake them optimal folders."
    },
    {
        "anchor": "Properties of twisted topological defects in 2D nematic liquid crystals: Topological defects are one of the most conspicuous features of liquid\ncrystals. In two dimensional nematics, they have been shown to behave\neffectively as particles with both, charge and orientation, which dictate their\ninteractions. Here, we study \"twisted\" defects that have a radially dependent\norientation. We find that twist can be partially relaxed through the creation\nand annihilation of defect pairs. By solving the equations for defect motion\nand calculating the forces on defects, we identify four distinct elements that\ngovern the relative relaxational motion of interacting topological defects,\nnamely attraction, repulsion, co-rotation and co-translation. The interaction\nof these effects can lead to intricate defect trajectories, which can be\ncontrolled by setting relevant timescales.",
        "positive": "Comment on 'Path Summation Formulation of the Master Equation': Comment on 'Path Summation Formulation of the Master Equation'"
    },
    {
        "anchor": "On local kirigami mechanics II: Stretchable creased solutions: Following on Part I of this work series on local kirigami mechanics, we\npresent a study of a discretely creased mechanism as a model to investigate the\nmechanics of the basic geometric building block of kirigami--the e-cone. We\nconsider an annular disk with a single radial slit discritised by a series of\nradial creases connecting kinematically flat rigid panels. The creases allow\nboth relative rotation and separation between panels, capturing both bending\nand stretching deformations. Admissible equilibrium configurations are obtained\nby penalising these deformations using elastic springs with stiffnesses derived\nfrom compatible continuum plate deformations. This provides a tool to study\nboth inextensible and extensible e-cone configurations due to opening of the\nslit and rotation of its lips. This creased model hence offers the possibility\nto study the e-cone away from its isometric limit, i.e., for plates with finite\nthickness, and explore the full range of post-buckling (far-from-threshold)\nbehaviour as well as initial buckling (near-threshold) instability. Our local\napproach provides a fundamental understanding of kirigami phenomenology,\nunderpinned by a proper theoretical approach to geometry and mechanics.",
        "positive": "Weak non-linearities of amorphous polymer under creep: The creep behavior of an amorphous poly(etherimide) (PEI) polymer is\ninvestigated in the vicinity of its glass transition in a weakly non linear\nregime where the acceleration of the creep response is driven by local\nconfigurational rearrangements. From the time shifts of the creep compliance\ncurves under increasing applied stresses in the range 1-15~\\si{\\mega\\pascal},\nwe determine a macroscopic acceleration factor. At the start of creep, the\nstress is homogeneous and the macroscopic acceleration can be assimilated to\nthat of the local rearrangements which is shown to vary as $f=e^{-(\\sigma/Y)^n}\n$ with $n=2 \\pm 0.2$, where $\\sigma$ is the local stress and $Y$ is a\ndecreasing function of compliance. This experimental result is in agreement\nwith the recent theory of Long \\textit{et al.} (\\textit{Phys. Rev. Mat.} (2018)\n\\textbf{2}, 105601 ) which predicts $n=2$. From a mean field approximation, we\ninterpret the variation of $Y$ with compliance as the result of the development\nof stress heterogneities during creep."
    },
    {
        "anchor": "Finite Phase-separation FRET I: A quantitative model valid for bilayer\n  nanodomains: Multicomponent lipid mixtures exhibit complex phase behavior, including\ncoexistence of nanoscopic fluid phases in ternary mixtures mimicking the\ncomposition of the outer leaflet of mammalian plasma membrane. The physical\nmechanisms responsible for the small size of phase domains are unknown, due in\npart to the difficulty of determining the size and lifetime distributions of\nsmall, fleeting domains. Steady-state FRET provides information about the\nspatial distribution of lipid fluorophores in a membrane, and with an\nappropriate model can be used to determine the size of phase domains. Starting\nfrom a radial distribution function for a binary hard disk fluid, we develop a\ndomain size-dependent model for stimulated acceptor emission. We compare the\nresults of the model to two similar, recently published models.",
        "positive": "The effect of finite pore length on ion structure and charging: Nanoporous supercapacitors play an important role in modern energy storage\nsystems, and their modeling is essential to predict and optimize the charging\nbehaviour. Two classes of models have been developed that consist of finite and\ninfinitely long pores. Here, we show that although both types of models predict\nqualitatively consistent results, there are important differences emerging due\nto the finite pore length. In particular, we find that the ion density inside a\nfinite pore is not constant but increases linearly from the pore entrance to\nthe pore end, where the ions form a strongly layered structure. This hinders a\ndirect quantitative comparison between the two models. In addition, we show\nthat although the ion density between the electrodes changes appreciably with\nthe applied potential, this change has a minor effect on charging. Our\nsimulations also reveal a complex charging behaviour, which is\nadsorption-driven at high voltages, but it is dominated either by co-ion\ndesorption or by adsorption of both types of ions at low voltages, depending on\nthe ion concentration."
    },
    {
        "anchor": "Solution scattering from colloidal curved plates: barrel tiles, scrolls\n  and spherical patches: I provide analytical or semi-analytical expressions for the small-angle\nscattering of colloidal objects that can be described as curved plates. These\nmodels could help characterize a variety of inorganic or biological systems.",
        "positive": "Waterlike Features, Liquid-Crystal Phase and Self-Assembly in Janus\n  Dumbbells: We use Molecular Dynamics simulations to explore the properties of dimmeric\nJanus nanoparticles. The nanoparticles are modeled as dumbbells. One kind of\nmonomer interacts by a Lennard-Jones potential, while the other specie of\nmonomer interacts though a two length scale potential. This specific two length\nscale potential do not present waterlike anomalies in bulk. However, our\nresults shows that, when combined in a dimmer, the Janus nanoparticle will have\nwaterlike anomalies. The self-assembly properties were also explored. We\nobserve several kinds of micelles, and a liquid-crystal phase. This results\nindicates that is possible to create Janus nanoparticles with waterlike\nfeatures using monomers without anomalous behavior. The anomalies and\nstructures are explained with the two length scale potential characteristics."
    },
    {
        "anchor": "Phase transition in the binary mixture of jammed particles with large\n  size dispersity: It has been well established that particulate systems show the jamming\ntransition and critical scaling behaviors associated with it. However, our\nknowledge is limited to (nearly) monodisperse systems. Recently, a binary\nmixture of jammed particles with large size dispersity was studied, and it was\nsuggested that two distinct jammed phases appeared. Here, we conduct a thorough\nnumerical study on this system with a special focus on the statistics of and\nfinite-size effects on the fraction of small particles that participate in the\nrigid network. We present strong evidence that two distinct jammed phases\nappear depending on the pressure and composition of two species, which are\nseparated by the first-order phase transition. In one of two phases, only large\nparticles are jammed, whereas both small and large particles are jammed in the\nother phase. We also describe the phase diagram in the pressure-composition\nplane, where the first-order phase transition line terminates at a critical\npoint. In addition, we investigate the mechanical properties in terms of the\nelastic moduli over the phase diagram and find that discontinuous changes in\nelastic moduli emerge across the phase transition. Remarkably, despite the\ndiscontinuities, the elastic moduli in each jammed phase exhibit identical\nscaling laws to those in the monodisperse systems.",
        "positive": "Probability of loops formation in star polymers in long range correlated\n  disorder: We analyze the statistics of loops formation in $f$-branched star polymers in\nan environment with structural defects, correlated at large distances $r$\naccording to a power law $\\sim r^{-a}$. Applying the direct polymer\nrenormalization approach, we found the values of the set of universal\nexponents, governing the scaling of probabilities of various types of loops in\nmacromolecules."
    },
    {
        "anchor": "Wrapping pathways of anisotropic dumbbell particles by giant unilamellar\n  vesicles: Endocytosis is a key cellular process involved in the uptake of nutrients,\npathogens or the diagnosis and therapy of diseases. Most studies have focused\non spherical objects, whereas biologically relevant shapes can be highly\nanisotropic. In this letter, we use an experimental model system based on Giant\nUnilamellar Vesicles (GUVs) and dumbbell-shaped colloidal particles to mimic\nand investigate the first stage of the passive endocytic process: engulfment of\nan anisotropic object by the membrane. Our model has specific ligand-receptor\ninteractions realized by mobile receptors on the vesicles and immobile ligands\non the particles. Through a series of experiments, theory and molecular\ndynamics simulations, we quantify the wrapping process of anisotropic dumbbells\nby GUVs and identify distinct stages of the wrapping pathway. We find that the\nstrong curvature variation in the neck of the dumbbell as well as membrane\ntension are crucial in determining both the speed of wrapping and the final\nstates.",
        "positive": "Intruders cooperatively interact with a wall into granular matter: When a cylindrical object penetrates granular matter near a vertical\nboundary, it experiences two effects: its center of mass moves horizontally\naway from the wall, and it rotates around its symmetry axis. Here we show\nexperimentally that, if two identical intruders instead of one are released\nside-by-side near the wall, both effects are also detected. However, unexpected\nphenomena appear due to a cooperative dynamics between the intruders. The net\nhorizontal distance traveled by the common center of mass of the twin intruders\nis much larger than that traveled by one intruder released at the same initial\ndistance from the wall, and the rotation is also larger. The experimental\nresults are well described by the Discrete Element Method, which reveals a\nfurther unexpected phenomenon: when four intruders are released as a column\nnear a wall, they penetrate like a chain that \"bends away\" from the wall so its\nlower end is very strongly repelled away from it."
    },
    {
        "anchor": "Self-assembly and glass-formation in a lattice model of telechelic\n  polymer melts: Influence of stiffness of the sticky bonds: The lattice cluster theory (LCT) for strongly interacting, self-assembling\ntelechelic polymers provides a theoretical tool that enables establishing the\nconnections between important microscopic molecular details of self-assembling\npolymers and their bulk thermodynamics. The original LCT for self-assembly of\ntelechelic polymers considers a model of fully flexible linear chains [J.\nDudowicz and K. F. Freed, J. Chem. Phys. \\textbf{136}, 064902 (2012)], while\nour recent work introduces a significant improvement to the LCT by including a\ndescription of chain semiflexibility for the bonds within each individual\ntelecheic chain [W.-S. Xu and K. F. Freed, J. Chem. Phys. \\textbf{143}, 024901\n(2015)], but the physically associative (or called \"sticky\") bonds between the\nends of the telechelics are left as fully flexible. Motivated by the ubiquitous\npresence of steric constraints on the association of real telechelic polymers\nthat impart an additional degree of bond stiffness (or rigidity), the present\npaper further extends the LCT to permit the sticky bonds to be semiflexible but\nto have a stiffness differing from that within each telechelic chain. An\nanalytical expression for the Helmholtz free energy is provided for this model\nof linear telechelic polymer melts, and illustrative calculations demonstrate\nthe significant influence of the stiffness of the sticky bonds on the\nself-assembly and thermodynamics of telechelic polymers. A brief discussion is\nalso provided for the impact of self-assembly on glass-formation by combining\nthe LCT description for this extended model of telechelic polymers with the\nAdam-Gibbs relation between the structural relaxation time and the\nconfigurational entropy.",
        "positive": "Relaxations and rheology near jamming: We determine the form of the complex shear modulus $G^*$ in soft sphere\npackings near jamming. Viscoelastic response at finite frequency is closely\ntied to a packing's intrinsic relaxational modes, which are distinct from the\nvibrational modes of undamped packings. We demonstrate and explain the\nappearance of an anomalous excess of slowly relaxing modes near jamming,\nreflected in a diverging relaxational density of states. From the density of\nstates, we derive the dependence of $G^*$ on frequency and distance to the\njamming transition, which is confirmed by numerics."
    },
    {
        "anchor": "Controlling the configuration space topology of mechanisms: Linkages are mechanical devices constructed from rigid bars and freely\nrotating joints studied both for their utility in engineering and as\nmathematical idealizations in a number of physical systems. Recently, there has\nbeen a resurgence of interest in designing linkages to perform certain tasks\nfrom the physics community. We describe a method to design the topology of the\nconfiguration space of a linkage by first identifying the manifold of critical\npoints, then perturbing around such critical configurations. We then\ndemonstrate our procedure by designing a mechanism to gate the propagation of a\nsoliton in a Kane-Lubensky chain of interconnected rotors.",
        "positive": "Dynamics of a Bose-Einstein condensate at finite temperature in an\n  atomoptical coherence filter: The macroscopic coherent tunneling through the barriers of a periodic\npotential is used as an atomoptical filter to separate the condensate and the\nthermal components of a $^{87}$Rb mixed cloud. We condense in the combined\npotential of a laser standing-wave superimposed on the axis of a cigar-shape\nmagnetic trap and induce condensate dipole oscillation in the presence of a\nstatic thermal component. The oscillation is damped due to interaction with the\nthermal fraction and we investigate the role played by the periodic potential\nin the damping process."
    },
    {
        "anchor": "Nucleation of colloids and macromolecules: does the nucleation pathway\n  matter?: A recent description of diffusion-limited nucleation based on fluctuating\nhydrodynamics that extends classical nucleation theory predicts a very\nnon-classical two-step scenario whereby nucleation is most likely to occur in\nspatially-extended, low-amplitude density fluctuations. In this paper, it is\nshown how the formalism can be used to determine the maximum probability of\nobserving \\emph{any} proposed nucleation pathway, thus allowing one to address\nthe question as to their relative likelihood, including of the newly proposed\npathway compared to classical scenarios. Calculations are presented for the\nnucleation of high-concentration bubbles in a low-concentration solution of\nglobular proteins and it is found that the relative probabilities (new theory\ncompared to classical result) for reaching a critical nucleus containing $N_c$\nmolecules scales as $e^{-N_c/3}$ thus indicating that for all but the smallest\nnuclei, the classical scenario is extremely unlikely.",
        "positive": "Monte Carlo simulation of binary mixtures of hard colloidal cuboids: We perform extensive Monte Carlo simulations to investigate the phase\nbehaviour of colloidal suspensions of hard board-like particles (HBPs). While\ntheories restricting particle orientation or ignoring higher ordered phases\nsuggest the existence of a stable biaxial nematic phase, our recent simulation\nresults on monodisperse systems indicate that this is not necessarily the case,\neven for particle shapes exactly in between prolate and oblate geometries,\nusually referred to as self-dual shape. Motivated by the potentially striking\nimpact of incorporating biaxial ordering into display applications, we extend\nour investigation to bidisperse mixtures of short and long HBPs and analyse\nwhether size dispersity can further enrich the phase behaviour of HBPs,\neventually destabilise positionally ordered phases and thus favour the\nformation of the biaxial nematic phase. Not only do our results indicate that\nbidisperse mixtures of self-dual shaped HBPs cannot self-assemble into biaxial\nnematic phases, but they also show that these particles are not able to form\nuniaxial nematic phases either. This surprising behaviour is also observed in\nmonodisperse systems. Additionally, bidisperse HBPs tend to phase separate in\ncoexisting isotropic and smectic phases or, at relatively large pressures, in a\nsmectic phase of mostly short HBPs and a smectic phase of mostly long HBPs. We\nconclude that limiting the particle orientational degrees of freedom or\nneglecting the presence of positionally ordered (smectic, columnar and crystal)\nphases can dramatically alter the phase behaviour of HBPs and unrealistically\nenlarge the region of stability of the biaxial nematic phase."
    },
    {
        "anchor": "The Physics of the Vicsek Model: In these lecture notes, prepared for the Microswimmers Summer School 2015 at\nForschungszentrum Juelich, I discuss the well known Vicsek model for collective\nmotion and its main properties. In particular, I discuss its algorithmical\nimplementation and the basic properties of its universality class. I present\nresults from numerical simulations and insist on the role played by symmetries\nand conservation laws. Analytical arguments are presented in an accessible and\nsimplified way, but ample references are given for more advanced readings.",
        "positive": "Three-dimensional vibrations of multilayered hollow spheres submerged in\n  a complex fluid: This paper presents a three-dimensional analytical study of the intrinsic\nfree vibration of an elastic multilayered hollow sphere interacting with an\nexterior non-Newtonian fluid medium. The fluid is assumed to be characterized\nby a compressible linear viscoelastic model accounting for both the shear and\ncompressional relaxation processes. For small-amplitude vibrations, the\nequations governing the viscoelastic fluid can be linearized, which are then\nsolved by introducing appropriate potential functions. The solid is assumed to\nexhibit a particular material anisotropy, i.e. spherical isotropy, which\nincludes material isotropy as a special case. The equations governing the\nanisotropic solid are solved in spherical coordinates using the state-space\nformalism, which finally establishes two separate transfer relations\ncorrelating the state vectors at the innermost surface with those at the\noutermost surface of the multilayered hollow sphere. By imposing the continuity\nconditions at the fluid-solid interface, two separate analytical characteristic\nequations are derived, which characterize two independent classes of vibration.\nNumerical examples are finally conducted to validate the theoretical derivation\nas well as to investigate the effects of various factors, including fluid\nviscosity and compressibility, fluid viscoelasticity, solid anisotropy and\nsurface effect, as well as solid intrinsic damping, on the vibration\ncharacteristics of the submerged hollow sphere. Particularly, our theoretically\npredicted vibration frequencies and quality factors of gold nanospheres with\nintrinsic damping immersed in water agree exceptionally well with the available\nexperimentally measured results. The reported analytical solution is truly and\nfully three-dimensional, covering from the purely radial breathing mode to\ntorsional mode to any general spheroidal mode."
    },
    {
        "anchor": "Capillary leveling of stepped films with inhomogeneous molecular\n  mobility: A homogeneous thin polymer film with a stepped height profile levels due to\nthe presence of Laplace pressure gradients. Here we report on studies of\npolymeric samples with precisely controlled, spatially inhomogeneous molecular\nweight distributions. The viscosity of a polymer melt strongly depends on the\nchain length distribution; thus, we learn about thin-film hydrodynamics with\nviscosity gradients. These gradients are achieved by stacking two films with\ndifferent molecular weights atop one another. After a sufficient time these\nsamples can be well described as having one dimensional viscosity gradients in\nthe plane of the film, with a uniform viscosity normal to the film. We develop\na hydrodynamic model that accurately predicts the shape of the experimentally\nobserved self-similar profiles. The model allows for the extraction of a\ncapillary velocity, the ratio of the surface tension and the viscosity, in the\nsystem. The results are in excellent agreement with capillary velocity\nmeasurements of uniform mono- and bi-disperse stepped films and are consistent\nwith bulk polymer rheology.",
        "positive": "Coherence length of an elongated condensate: a study by matter-wave\n  interferometry: We measure the spatial correlation function of Bose-Einstein condensates in\nthe cross-over region between phase-coherent and strongly phase-fluctuating\ncondensates. We observe the continuous path from a gaussian-like shape to an\nexponential-like shape characteristic of one-dimensional phase-fluctuations.\nThe width of the spatial correlation function as a function of the temperature\nshows that the condensate coherence length undergoes no sharp transition\nbetween these two regimes."
    },
    {
        "anchor": "Optical Probe Diffusion in Polymer Solutions: The experimental literature on the motion of mesoscopic probe particles\nthrough polymer solutions is systematically reviewed. The primary focus is the\nstudy of diffusive motion of small probe particles. Comparison is made with\nmeasurements of solution viscosities. A coherent description was obtained,\nnamely that the probe diffusion coefficient generally depends on polymer\nconcentration as D_p = D_0 exp(-alpha c^nu). One finds that alpha depends on\npolymer molecular weights as alpha ~ M^0.8, and \\nu appears to have large-M and\nsmall-M values with a crossover linking them. The probe diffusion coefficient\ndoes not simply track the solution viscosity; instead, D_p eta typically\nincreases markedly with increasing polymer concentration and molecular weight.\nIn some systems, e.g., hydroxypropylcellulose:water, the observed probe spectra\nare bi- or tri-modal. Extended analysis of the full probe phenomenology implies\nthat hydroxypropylcellulose solutions are characterized by a single,\nconcentration-independent, length scale that is approximately the size of a\npolymer coil. In a very few systems, one sees re-entrant or\nlow-concentration-plateau behaviors of uncertain interpretation; from their\nrarity, these behaviors are reasonably interpreted as corresponding to specific\nchemical effects. True microrheological studies examining the motion of\nmesoscopic particles under the influence of a known external force are also\nexamined. Viscosity from true microrheological measurements is in many cases\nsubstantially smaller than the viscosity measured with a macroscopic\ninstrument.",
        "positive": "Phase Transitions In An Implicit Solvent Minimal Model Of Lipids: Role\n  Of Head-Tail Size Ratio: We present Monte Carlo simulations under constant NVT conditions on a minimal\nthree beads coarse grained implicit solvent model of lipid molecules, with the\nhydrophilic head represented by one bead and the hydrophobic tail represented\nby two beads. We consider two lipids, one with the head and tail bead sizes\nequal and the other with the tail beads smaller than the head. When cooled to\nthe ambient temperature from an initial isotropic phase at high temperature,\nthe first lipid transforms spontaneously to a lamellar phase while the second\nlipid transforms to a micellar phase, showing the crucial role of the head and\ntail size ratio on lipid phases."
    },
    {
        "anchor": "Packing Fractions and Maximum Angles of Stability of Granular Materials: In two-dimensional rotating drum experiments, we find two separate influences\nof the packing fraction of a granular heap on its stability. For a fixed grain\nshape, the stability increases with packing fraction. However, in determining\nthe relative stability of different grain shapes, those with the lowest average\npacking fractions tend to form the most stable heaps. We also show that only\nthe configuration close to the surface of the pile figures prominently.",
        "positive": "Electric double layer structure close to the three-phase contact line in\n  an electrolyte wetting a solid substrate: The electric double layer structure in an electrolyte close to a solid\nsubstrate near the three-phase contact line is approximated by considering the\nlinearized Poisson-Boltzmann equation in a wedge geometry. The mathematical\napproach complements the semi-analytical solutions reported in the literature\nby providing easily available characteristic information on the double layer\nstructure. In particular, the model contains a length scale that quantifies the\ndistance from the fluid-fluid interface over which this boundary influences the\nelectric double layer. The analysis is based on an approximation for the\nequipotential lines. Excellent agreement between the model predictions and\nnumerical results is achieved for a significant range of contact angles. The\nlength scale quantifying the influence of the fluid-fluid interface is\nproportional to the Debye length and depends on the wall contact angle. It is\nshown that for contact angles approaching 90{\\deg} there is a finite range of\nboundary influence."
    },
    {
        "anchor": "Single-Molecule Lamellar Hydrogels from Bolaform Microbial Glucolipids: Lipid lamellar hydrogels are rare soft fluids composed of a phospholipid\nlamellar phase instead of fibrillar networks. The mechanical properties of\nthese materials are controlled by defects, induced by local accumulation of a\npolymer or surfactant in a classical lipid bilayer. Herein we report a new\nclass of lipid lamellar hydrogels composed of one single bolaform glycosylated\nlipid obtained by fermentation. The lipid is self-organized into flat\ninterdigitated membranes, stabilized by electrostatic repulsive forces and\nstacked in micrometer-sized lamellar domains. The defects in the membranes and\nthe interconnection of the lamellar domains are responsible, from the nano- to\nthe micrometer scales, for the elastic properties of the hydrogels. The\nlamellar structure is probed by combining small angle x-ray and neutron\nscattering (SAXS, SANS), the defect-rich lamellar domains are visualized by\npolarized light microscopy while the elastic properties are studied by\noscillatory rheology. The latter show that both storage G' and loss G'' moduli\nscale as a weak power-law of the frequency, that can be fitted with fractional\nrheology models. The hydrogels possess rheo-thinning properties with\nsecond-scale recovery. We also show that ionic strength is not only necessary,\nas one could expect, to control the interactions in the lamellar phase but,\nmost importantly, it directly controls the elastic properties of the lamellar\ngels.",
        "positive": "Temperature Dependence of Vortex Nucleation in Gaseous Bose-Einstein\n  Condensates: The formation of quantized vortices in trapped, gaseous Bose-Einstein\ncondensates is considered. The thermodynamic stability of vortex states and the\nessential role of the surface excitations as a route for vortex penetration\ninto the condensate are discussed. Special focus is on finite-temperature\neffects of the vortex nucleation process. It is concluded that the critical\nangular frequencies for exciting surface modes with the relevant\nmultipolarities yield, also at finite temperatures, the appropriate thresholds\nfor the nucleation of vortices in dilute Bose-Einstein condensates, in fair\nagreement with the recent experiments."
    },
    {
        "anchor": "Critical Phenomena of Single and Double Polymer Strands in a Solution: A universality class describing the statistics of the merging of two single\npolymer strands to a double polymer strand and the reverse process is examined.\nThe polymers can have an intrinsic direction, and the simpler case, where only\nsingle strands aligned parallel bind to a double strand is considered in\ndetail. The critical dimension of the universality class is six, there is a\nstable fixed point and critical exponents are calculated with renormalization\ngroup and loop expansion. The corresponding field theory describes polymer\nconfigurations in terms of fields and not in terms of coordinate paths and is\nsecond quantized in this sense.",
        "positive": "Ratio of effective temperature to pressure controls the mobility of\n  sheared hard spheres: Using molecular dynamics simulation, we calculate fluctuations and response\nfor steadily sheared hard spheres over a wide range of packing fractions $\\phi$\nand shear strain rates $\\gamma$, using two different methods to dissipate\nenergy. To a good approximation, shear stress and density fluctuations are\nrelated to their associated response functions by a single effective\ntemperature $T_{eff}$ that is equal to or larger than the kinetic temperature\n$T_{kin}$. We find a crossover in the relationship between the relaxation time\n$\\tau$ and the the nondimensionalized effective temperature\n$T_{eff}/p\\sigma^3$, where $p$ is the pressure and $\\sigma$ is the sphere\ndiameter. In the solid response regime, the behavior at fixed packing fraction\nsatisfies $\\tau\\gamma\\propto \\exp(-cp\\sigma^3/T_{eff})$, where $c$ depends\nweakly on $\\phi$, suggesting that the average local yield strain is controlled\nby the effective temperature in a way that is consistent with shear\ntransformation zone theory. In the fluid response regime, the relaxation time\ndepends on $T_{eff}/p\\sigma^3$ as it depends on $T_{kin}/p\\sigma^3$ in\nequilibrium. This regime includes both near-equilibrium conditions where\n$T_{eff} ~ T_{kin}$ and far-from-equilibrium conditions where $T_{eff} \\ne\nT_{kin}$. We discuss the implications of our results for systems with soft\nrepulsive interactions."
    },
    {
        "anchor": "Metastable Intermediates in the Condensation of Semiflexible Polymers: Motivated by results from an earlier Brownian Dynamics (BD) simulation for\nthe collapse of a single, stiff polymer in a poor solvent [B. Schnurr, F. C.\nMacKintosh, and D. R. M. Williams, Europhys. Lett. 51 (3), 279 (2000)] we\ncalculate the conformational energies of the intermediate (racquet) states\nsuggested by the simulations. In the absence of thermal fluctuations (at zero\ntemperature) the annealed shapes of these intermediates are well-defined in\ncertain limits, with their major structural elements given by a particular case\nof Euler's elastica. In appropriate units, a diagram emerges which displays the\nrelative stability of all states, tori and racquets. We conclude that, in\nmarked contrast to the collapse of flexible polymers, the condensation of\nsemiflexible or stiff polymers generically proceeds via a cascade through\nmetastable intermediates, the racquets, towards a ground state, the torus or\nring, as seen in the dynamical simulations.",
        "positive": "Impact of $BaTiO_3$ nanoparticles on pretransitional effects in liquid\n  crystalline dodecylcyanobiphenyl: The pretransitional behavior of dodecylcyanobiphenyl (12CB)\n(isotropic-smectic-A-solid mesomorphism) with $d = 50$ nm $BaTiO_3$\nnanoparticles (NPs) linked the cubic phase was monitored via temperature\nstudies of dielectric constant. Tests were carried out in the isotropic, liquid\ncrystal mesomorphic and solid phases. For each phase transition the same value\nof the critical exponent $\\alpha=0.5$ was obtained, including nanocolloids. All\nphase transitions show the weakly discontinuous nature. The temperature metric\nof the discontinuity dT notably decreases when adding nanoparticles. The\naddition of nanoparticles first decreases the dielectric constant by approx.\n$50%$ in comparison with pure 12CB, but already for a concentration $x = 0.4%%\nNPs an increase over $50%$ takes place. It is notable that for the latter\nconcentration unique hallmarks of the pretransitional effect emerge also for\nthe solid-mesophase transition. All thease indicate the important impact of\nnanoparticles on multimolecular mesoscale fluctuations."
    },
    {
        "anchor": "Fluids in Extreme Confinement: For extremely confined fluids with two-dimensional density $n$ in slit\ngeometry of accessible width $L$, we prove that in the limit $L\\to 0$ the\nlateral and transversal degrees of freedom decouple, and the latter become\nideal-gas-like. For small wall separation the transverse degrees of freedom can\nbe integrated out and renormalize the interaction potential. We identify $n L^2\n$ as hidden smallness parameter of the confinement problem and evaluate the\neffective two-body potential analytically, which allows calculating the leading\ncorrection to the free energy exactly. Explicitly, we map a fluid of hard\nspheres in extreme confinement onto a 2d-fluid of disks with an effective\nhard-core diameter and a soft boundary layer. Two-dimensional phase transitions\nare robust and the transition point experiences a shift ${\\cal O}(n L^2)$.",
        "positive": "Hydrodynamic interaction in quasi-two-dimensional suspensions: Confinement between two parallel surfaces is found, theoretically and\nexperimentally, to drastically affect the hydrodynamic interaction between\ncolloid particles, changing the sign of the coupling, its decay with distance\nand its concentration dependence. In particular, we show that three-body\neffects do not modify the coupling at large distances as would be expected from\nhydrodynamic screening."
    },
    {
        "anchor": "Elastic chiral Landau level and snake states in origami metamaterials: In this study, we present a method for generating a synthetic gauge field in\norigami metamaterials with continuously varying geometrical parameters. By\nmodulating the mass term in the Dirac equation linearly, we create a synthetic\ngauge field in the vertical direction, which allows for the quantization of\nLandau levels through the generated pseudomagnetic field. Furthermore, we\ndemonstrate the existence and robustness of the chiral zeroth Landau level. The\nunique elastic snake state is realized using the coupling between the zeroth\nand the first Landau levels. Our results, supported by theory and simulations,\nestablish a feasible framework for generating pseudomagnetic fields in origami\nmetamaterials with potential applications in waveguides and cloaking.",
        "positive": "Structural characterization of the interfacial self-assembly of chitosan\n  with oppositely charged surfactant: Controlling the assembly of polyelectrolytes and surfactant at liquid-liquid\ninterfaces offers new ways to fabricate soft materials with specific physical\nproperties. However, little is known of the relationships between the kinetics\nof interfacial assembly, structural and rheological properties of such\ninterfaces. We studied the kinetics at water-oil interface of the assembly of a\npositively charged biopolymer, chitosan, with an anionic fatty acid using a\nmulti-scale approach. The growth kinetics of the membrane was followed by\ninterfacial rheometry and space- and time- resolved dynamic light scattering.\nThis set of techniques revealed that the interfacial complexation was a\nmulti-step process. At short time-scale, the interface was fluid and made of\nheterogeneous patches. At a 'gelation' time, the surface elastic modulus and\nthe correlation between speckles increased sharply meaning that the patches\npercolated. Confocal and electron microscopy confirmed this picture, and\nrevealed that the basic brick of the membrane was sub-micrometric aggregates of\nchitosan / fatty acid."
    },
    {
        "anchor": "Liquid bridging of cylindrical colloids in near-critical solvents: Within mean field theory, we investigate the bridging transition between a\npair of parallel cylindrical colloids immersed in a binary liquid mixture as a\nsolvent which is close to its critical consolute point $T_c$. We determine the\nuniversal scaling functions of the effective potential and of the force between\nthe colloids. For a solvent which is at the critical concentration and close to\n$T_c$, we find that the critical Casimir force is the dominant interaction at\nclose separations. This agrees very well with the corresponding Derjaguin\napproximation for the effective interaction between the two cylinders, while\ncapillary forces originating from the extension of the liquid bridge turn out\nto be more important at large separations. In addition, we are able to infer\nfrom the wetting characteristics of the individual colloids the first-order\ntransition of the liquid bridge connecting two colloidal particles to the\nruptured state. While specific to cylindrical colloids, the results presented\nhere provide also an outline for identifying critical Casimir forces acting on\nbridged colloidal particles as such, and for analyzing the bridging transition\nbetween them.",
        "positive": "Exact polarization energy for clusters of contacting dielectrics: The induced surface charges appear to diverge when dielectric particles form\nclose contacts. Resolving this singularity numerically is prohibitively\nexpensive because high spatial resolution is needed. We show that the strength\nof this singularity is logarithmic in both inter-particle separation and\ndielectric permittivity. A regularization scheme is proposed to isolate this\nsingularity, and to calculate the exact cohesive energy for clusters of\ncontacting dielectric particles. The results indicate that polarization energy\nstabilizes clusters of open configurations when permittivity is high, in\nagreement with the behavior of conducting particles, but stabilizes the compact\nconfigurations when permittivity is low."
    },
    {
        "anchor": "Rheology of Granular Rafts: Rheology of macroscopic particle-laden interfaces, called \"Granular Rafts\"\nhas been experimentally studied, in the simple shear configuration. The\nshear-stress relation obtained from a classical rheometer exhibits the same\nbehavior as a Bingham fluid and the viscosity diverges with the surface\nfraction according to evolutions similar to 2D suspensions. The velocity field\nof the particles that constitute the granular raft has been measured in the\nstationary state. These measurements reveal non-local rheology similar to dry\ngranular materials. Close to the walls of the rheometer cell, one can observe\nregions of large local shear rate while in the middle of the cell a quasistatic\nzone exists. This flowing region, characteristic of granular matter, is\ndescribed in the framework of an extended kinetic theory showing the evolution\nof the velocity profile with the imposed shear stress. Measuring the\nprobability density functions of the elementary strains, we provide evidence of\na balance between positive and negative elementary strains. This behavior is\nthe signature of a quasistatic region inside the granular raft.",
        "positive": "Liquid crystal-enabled electrophoresis of spheres in a nematic medium\n  with negative dielectric anisotropy: We describe electrophoresis of spherical dielectric particles in a uniformly\naligned nematic medium with a negative dielectric anisotropy. A spherical\nparticle that orients the liquid crystal (LC) perpendicularly to its surface\nmoves under the application of the uniform direct current (DC) or alternating\ncurrent (AC) electric field. The electric field causes no distortions of the LC\ndirector far away from the sphere. Electrophoresis in the nematic LC shows two\ntypes of nonlinearity in the velocity vs. field dependence. The velocity\ncomponent parallel to the applied electric field grows linearly with the field,\nbut when the field is high enough, it also shows a cubic dependence. The most\ninteresting is the second type of nonlinear electrophoresis that causes the\nsphere to move perpendicularly to the applied field. This perpendicular\ncomponent of velocity is proportional to the square of the field. The effect\nexists only in a LC and disappears when the material is melted into an\nisotropic fluid. The quadratic effect is caused by the dipolar symmetry of\ndirector distortions around the sphere and is classified as an LC-enabled\nelectrophoresis (LCEEP). The nonlinear electrophoretic mobility of particles in\nLCEEP offers a rich variety of control parameters to design 3D trajectories of\nparticles for microfluidic and optofluidic applications."
    },
    {
        "anchor": "Dimensionality and viscosity exponent in shear-driven jamming: Collections of bidisperse frictionless particles at zero temperature in three\ndimensions are simulated with a shear-driven dynamics with the aim to compare\nwith behavior in two dimensions. Contrary to the prevailing picture, and in\ncontrast to results from isotropic jamming from compression or quench, we find\nthat the critical exponents in three dimensions are different from those in two\ndimensions and conclude that shear-driven jamming in two and three dimensions\nbelong to different universality classes.",
        "positive": "Confinement of knotted polymers in a slit: We investigate the effect of knot type on the properties of a ring polymer\nconfined to a slit. For relatively wide slits, the more complex the knot, the\nmore the force exerted by the polymer on the walls is decreased compared to an\nunknotted polymer of the same length. For more narrow slits the opposite is\ntrue. The crossover between these two regimes is, to first order, at smaller\nslit width for more complex knots. However, knot topology can affect these\ntrends in subtle ways. Besides the force exerted by the polymers, we also study\nother quantities such as the monomer-density distribution across the slit and\nthe anisotropic radius of gyration."
    },
    {
        "anchor": "Influence of particle size on ice nucleation and growth during the\n  freeze-casting process: The solidification behaviour of suspensions of alumina particles during\ndirectional solidification is investigated here by in situ observations using\nX-ray radiography and tomography. The objective of this study is to assess the\ninfluence of particle size on the solidification behaviour of the suspensions\nduring the early stages of solidification. Four powders with particle size in\nthe range 0.2-3.4{\\mu}m (median size) were investigated. Solidification is\nobtained by cooling at a constant rate, starting from room temperature.\nAttention is specifically paid to the nucleation and growth behaviour of the\nice crystals in these suspensions. We propose that the nucleation of ice\ncrystals is controlled by the particle size, the surface of the particles\nacting as nucleation sites. Smaller particle size leads to a lower degree of\nsupercooling since nucleation and growth can proceed at higher temperature than\nwith larger particles. The initial interface velocity is dependent on the\ndegree of supercooling, and controls the extent of the initial structural\ngradient in the resulting porous materials.",
        "positive": "Probing shapes of microbes using liquid crystal textures: We propose a novel technique to probe shape of a single microbe embedded in a\nnematic liquid crystal (NLC) sample by observing geometry of dark brushes with\noptical microscope using a cross-polarizer set up. Assuming certain anchoring\nconditions for the NLC director at the surface of the microbe, we determine the\nresulting shapes of brushes using numerical simulations. Our results suggest\nthat for asymmetrical microbes (such as cylindrical shaped bacteria/viruses),\nresulting brushes may carry the imprints of this asymmetry (e.g. the aspect\nratio of cylindrical shape) at relatively large distances to be able to be seen\nusing simple optical microscopy even for microbe sizes in few tens to few\nhundred nanometer range."
    },
    {
        "anchor": "Effects of Thermal Noise on Pattern Onset in Continuum Simulations of\n  Shaken Granular Layers: The author investigates the onset of patterns in vertically oscillated layers\nof dissipative particles using numerical solutions of continuum equations to\nNavier-Stokes order. Above a critical accelerational amplitude of the cell,\nstanding waves form stripe patterns which oscillate subharmonically with\nrespect to the cell. Continuum simulations neglecting interparticle friction\nyield pattern wavelengths consistent with experiments using frictional\nparticles. However, the critical acceleration for standing wave formation is\napproximately 10% lower in continuum simulations without added noise than in\nmolecular dynamics simulations. This report incorporates fluctuating\nhydrodynamics theory into continuum simulations by adding noise terms with no\nfit parameters; this modification yields a critical acceleration in agreement\nwith molecular dynamics simulations.",
        "positive": "Interaction energy between two charged spheres surrounded by\n  electrolyte. The smaller sphere located inside the larger sphere: By using the recently generalized version of Newton Shell Theorem [3]\nanalytical equations are derived to calculate the electric interaction energy\nbetween two charged spheres, a small one is located within a larger one, and\neach sphere is surrounded outside and inside by electrolyte. This electric\ninteraction energy is calculated as a function of the electrolyte ion\nconcentration, temperature, distance between the centers and size of the\nspheres. At the same distance between the centers of the spheres the absolute\nvalue of the interaction energy decreases with increasing electrolyte ion\nconcentration and increases with increasing temperature. At zero electrolyte\nion concentration the derived analytical equation transforms into the result of\nthe Shell Theorem. Finally, the analytical equation is generalized to calculate\nthe total electric interaction energy between a large charged sphere and N\nsmall charged spheres (located within the large sphere) where the spheres are\nsurrounded by electrolyte."
    },
    {
        "anchor": "Minimal distance transformations between links and polymers: Principles\n  and examples: The calculation of Euclidean distance between points is generalized to\none-dimensional objects such as strings or polymers. Necessary and sufficient\nconditions for the minimal transformation between two polymer configurations\nare derived. Transformations consist of piecewise rotations and translations\nsubject to Weierstrass-Erdmann corner conditions. Numerous examples are given\nfor the special cases of one and two links. The transition to a large number of\nlinks is investigated, where the distance converges to the polymer length times\nthe mean root square distance (MRSD) between polymer configurations, assuming\ncurvature and non-crossing constraints can be neglected. Applications of this\nmetric to protein folding are investigated. Potential applications are also\ndiscussed for structural alignment problems such as pharmacophore\nidentification, and inverse kinematic problems in motor learning and control.",
        "positive": "Quenched disorder and spin-glass correlations in XY nematics: We present a theoretical study of the equilibrium ordering in a 3D XY nematic\nsystem with quenched random disorder. Within this model, treated with the\nreplica trick and Gaussian variational method, the correlation length is\nobtained as a function of the local nematic order parameter and the effective\ndisorder strength. These results clarify what happens in the limiting cases of\ndiminishing order parameter and disorder strength, that is near a phase\ntransition of a pure system. In particular, it is found that quenched disorder\nis irrelevant as the order parameter tends to zero and hence does not change\nthe character of the continuous XY nematic to isotropic phase transition. We\ndiscuss how these results compare with experiments and simulations"
    },
    {
        "anchor": "On the rising and sinking of granular bubbles and droplets: Recently, the existence of so-called granular bubbles and droplets has been\ndemonstrated experimentally. Granular bubbles and droplets are clusters of\nparticles that respectively rise and sink if submerged in an aerated and\nvibrated bed of another granular material of different size and/or density.\nHowever, currently there is no model that explains the coherent motion of these\nclusters and predicts the transition between a rising and sinking motion. Here,\nwe propose an analytical model predicting accurately the neutral buoyancy limit\nof a granular bubble/droplet. This model allows the compilation of a regime map\nidentifying five distinct regimes of granular bubble/droplet motion.",
        "positive": "Avalanches mediate crystallization in a hard-sphere glass: By molecular-dynamics simulations, we have studied the devitrification (or\ncrystallization) of aged hard-sphere glasses. First, we find that the dynamics\nof the particles are intermittent: Quiescent periods, when the particles simply\n\"rattle\" in their nearest-neighbor cages, are interrupted by abrupt\n\"avalanches,\" where a subset of particles undergo large rearrangements. Second,\nwe find that crystallization is associated with these avalanches but that the\nconnection is not straightforward. The amount of crystal in the system\nincreases during an avalanche, but most of the particles that become\ncrystalline are different from those involved in the avalanche. Third, the\noccurrence of the avalanches is a largely stochastic process. Randomizing the\nvelocities of the particles at any time during the simulation leads to a\ndifferent subsequent series of avalanches. The spatial distribution of\navalanching particles appears random, although correlations are found among\navalanche initiation events. By contrast, we find that crystallization tends to\ntake place in regions that already show incipient local order."
    },
    {
        "anchor": "Generalised Einstein Relation for Hot Brownian Motion: The Brownian motion of a hot nanoparticle is described by an effective Markov\ntheory based on fluctuating hydrodynamics. Its predictions are scrutinized over\na wide temperature range using large-scale molecular dynamics simulations of a\nhot nanoparticle in a Lennard-Jones fluid. The particle positions and momenta\nare found to be Boltzmann distributed according to distinct effective\ntemperatures $T_\\mathrm{HBM}$ and $T_\\mathrm{k}$ . For $T_\\mathrm{HBM}$ we\nderive a formally exact theoretical prediction and establish a generalised\nEinstein relation that links it to directly measurable quantities.",
        "positive": "Pattern Formation During Deformation of a Confined Viscoelastic Layer:\n  From a Viscous Liquid to a Soft Elastic Solid: We study pattern formation during tensile deformation of confined\nviscoelastic layers. The use of a model system (PDMS with different degrees of\ncrosslinking) allows us to go continuously from a viscous liquid to an elastic\nsolid. We observe two distinct regimes of fingering instabilities: a regime\ncalled \"elastic\" with interfacial crack propagation where the fingering\nwavelength only scales with the film thickness, and a bulk regime called\n\"viscoelastic\" where the fingering instability shows a Saffman-Taylor-like\nbehavior. We find good quantitative agreement with theory in both cases and\npresent a reduced parameter describing the transition between the two regimes\nand allowing to predict the observed patterns over the whole range of\nviscoelastic properties."
    },
    {
        "anchor": "Inertia suppresses signatures of activity of active Brownian particles\n  in a harmonic potential: A harmonically trapped active Brownian particle exhibits two types of\npositional distributions -- one has a single peak, the other has a single well\n-- that signify steady-state dynamics with low and high activity, respectively.\nAdding inertia to the translational motion preserves this strict single\npeak/well classification of the densities but shifts the dividing boundary\nbetween the states in the parameter space. We characterize this shift for the\ndynamics in one spatial dimension using the static Fokker--Planck equation for\nthe full joint distribution of the state space. We derive local results\nanalytically with a perturbation method for a small rotational velocity and\nthen extend them globally with a numerical approach",
        "positive": "Segregation in desiccated sessile drops of biological fluids: It is shown here that concurrence between advection and diffusion in a drying\nsessile drop of a biological fluid can produce spatial redistribution of\nalbumen and salt. The result gives an explanation for the patterns observed in\nthe dried drops of the biological fluids."
    },
    {
        "anchor": "Designing non-segregating granular mixtures: In bidisperse particle mixtures varying in size or density alone, large\nparticles rise (driven by percolation) and heavy particles sink (driven by\nbuoyancy). When the two particle species differ from each other in both size\nand density, the two segregation mechanisms either enhance (large/light and\nsmall/heavy) or oppose (large/heavy and small/light) each other. In the latter\ncase, an equilibrium condition exists in which the two segregation mechanisms\nbalance and the particles no longer segregate. This leads to a methodology to\ndesign non-segregating particle mixtures by specifying particle size ratio,\ndensity ratio, and mixture concentration to achieve the equilibrium condition.\nUsing DEM simulations of quasi-2D bounded heap flow, we show that segregation\nis significantly reduced for particle mixtures near the equilibrium condition.\nIn addition, the rise-sink transition for a range of particle size and density\nratios matches the combined size and density segregation model predictions.",
        "positive": "Mitigating Density Fluctuations in Particle-based Active Nematic\n  Simulations: Understanding active matter has led to new perspectives on biophysics and\nnon-equilibrium dynamics. However, the development of numerical tools for\nsimulating active fluids capable of incorporating non-trivial boundaries or\ninclusions has lagged behind. Active particle-based methods, which typically\nexcel at this, suffer from large density fluctuations that affect the dynamics\nof inclusions. To this end, we advance the Active-Nematic Multi-Particle\nCollision Dynamics algorithm, a particle-based method for simulating active\nnematics, by addressing the large density fluctuations that arise from\nactivity. This paper introduces three novel activity formulations that mitigate\nthe coupling between activity and local density. Local density fluctuations are\ndecreased to a level comparable to the passive limit while retaining the\nphenomenology of active nematics and increasing the active turbulence regime\nfour-fold. These developments extend the technique into a flexible tool for\nmodeling active systems, including solutes and inclusions, with broad\napplications for the study of biophysical systems."
    },
    {
        "anchor": "Procedure to construct a multi-scale coarse-grained model of DNA-coated\n  colloids from experimental data: We present a quantitative, multi-scale coarse-grained model of DNA coated\ncolloids. The parameters of this model are transferable and are solely based on\nexperimental data. As a test case, we focus on nano-sized colloids carrying\nsingle-stranded DNA strands of length comparable to the colloids' size. We show\nthat in this regime, the common theoretical approach of assuming pairwise\nadditivity of the colloidal pair interactions leads to quantitatively and\nsometimes even qualitatively wrong predictions of the phase behaviour of\nDNA-grafted colloids. Comparing to experimental data, we find that our\ncoarse-grained model correctly predicts the equilibrium structure and melting\ntemperature of the formed solids. Due to limited experimental information on\nthe persistence length of single-stranded DNA, some quantitative discrepancies\nare found in the prediction of spatial quantities. With the availability of\nbetter experimental data, the present approach provides a path for the rational\ndesign of DNA-functionalised building blocks that can self-assemble in complex,\nthree-dimensional structures.",
        "positive": "Engineering Entropy for the Inverse Design of Colloidal Crystals from\n  Hard Shapes: Throughout the physical sciences, entropy stands out as a pivotal but\nenigmatic concept that, in materials design, often takes a backseat to energy.\nHere, we demonstrate how to precisely engineer entropy to achieve desired\ncolloidal crystals. We demonstrate the inverse design of hard particles that\nassemble six different target colloidal crystals due solely to entropy\nmaximization. Our approach efficiently samples $10^8$ particle shapes from 88-\nand 192-dimensional design spaces to discover thermodynamically optimal shapes.\nWe design particle shapes that self assemble known crystals with optimized\nthermodynamic stability, as well as new crystal structures with no known atomic\nor other equivalent."
    },
    {
        "anchor": "Hierarchical porous materials made by stereolithographic printing of\n  photo-curable emulsions: Porous materials are relevant for a broad range of technologies from\ncatalysis and filtration, to tissue engineering and lightweight structures.\nControlling the porosity of these materials over multiple length scales often\nleads to enticing new functionalities and higher efficiency but has been\nlimited by manufacturing challenges and the poor understanding of the\nproperties of hierarchical structures. Here, we report an experimental platform\nfor the design and manufacturing of hierarchical porous materials via the\nstereolithographic printing of stable photo-curable Pickering emulsions. In the\nprinting process, the micron-sized droplets of the emulsified resins work as\nsoft templates for the incorporation of microscale porosity within sequentially\nphoto-polymerized layers. The light patterns used to polymerize each layer on\nthe building stage further generate controlled pores with bespoke\nthree-dimensional geometries at the millimetre scale. Using this combined\nfabrication approach, we create architectured lattices with mechanical\nproperties tuneable over several orders of magnitude and large complex-shaped\ninorganic objects with unprecedented porous designs.",
        "positive": "Direct Assembly of Magnetic Janus Particles at a Droplet Interface: Self-assembly of nanoparticles at fluid-fluid interfaces is a promising route\nto fabricate functional materials from the bottom-up. However, directing and\ncontrolling particles into highly tunable and predictable structures -- while\nessential -- is a challenge. We present a liquid interface assisted approach to\nfabricate nanoparticle structures with tunable properties. To demonstrate its\nfeasibility, we study magnetic Janus particles adsorbed at the interface of a\nspherical droplet placed on a substrate. With an external magnetic field turned\non, a single particle moves to the location where its position vector relative\nto the droplet centre is parallel to the direction of the applied field.\nMultiple magnetic Janus particles arrange into reconfigurable hexagonal lattice\nstructures and can be directed to assemble at desirable locations on the\ndroplet interface by simply varying the magnetic field direction. We develop an\ninterface energy model to explain our observations, finding excellent\nagreement. Finally, we demonstrate that the external magnetic field allows\n\\revisedtext{one} to tune the particle deposition pattern obtained when the\ndroplet evaporates. Our results have implications for the fabrication of varied\nnanostructures on substrates for use in nanodevices, organic electronics, or\nadvanced display, printing and coating applications."
    },
    {
        "anchor": "Hydrophobic Interactions and Dewetting between Plates with Hydrophobic\n  and Hydrophilic Domains: We study by molecular dynamics simulations the wetting/dewetting transition\nand the dependence of the free energy on distance between plates that contain\nboth hydrophobic and hydrophilic particles. We show that dewetting and strength\nof hydrophobic interaction is very sensitive to the distribution of hydrophobic\nand hydrophilic domains. In particular, we find that plates characterized by a\nlarge domain of hydrophobic sites induce a dewetting transition and an\nattractive solvent-induced interaction. On the other hand, a homogeneous\ndistribution of the hydrophobic and hydrophilic particles on the plates\nprevents the dewetting transition and produces a repulsive solvent-induced\ninteraction. We also present results for a kind of Janus interface in which one\nplate consists of hydrophobic particles and the other of hydrophilic particles\nshowing that the inter-plate gap remains wet until steric constraints at small\nseparations eject the water molecules. Our results indicate that the Cassie\nequation, for the contact angle of a heterogeneous plate, can not be used to\npredict the critical distance of dewetting. These results indicate that\nhydrophobic interactions between nanoscale surfaces with strong large\nlength-scale hydrophobicity can be highly cooperative and thus they argue\nagainst additivity of the hydrophobic interactions between different surface\ndomains in these cases. These findings are pertinent to certain protein-protein\ninteractions where additivity is commonly assumed.",
        "positive": "Trimodal Charge Transport in Polar Liquid based Dilute Nanoparticulate\n  Colloidal Dispersions: The dominant modes of charge transport in variant polar liquid based\nnanoparticulate colloidal dispersions (dilute) have been theorized. Theories\nformulating electrical characteristics of colloids have often been found to\nover or under predict charge transport in dilute suspensions of nanoparticles\nin polar fluids owing to grossly different mechanistic behavior of concentrated\nsystems. Three major interacting modes with independent yet simultaneous\nexistence have been proposed and found to be consistent with analyses of\nexperimental data. Electric Double Layer (EDL) formation at nanoparticle fluid\ninterface conjugated electrophoresis under the influence of the electric field\nhas been determined as one important mode of charge transport. Nanoparticle\npolarization due to short range field non-uniformity caused by the EDL with\nconsequent particle motion due to interparticle electrostatic interactions acts\nas another mode of transport. Coupled electrothermal diffusion arising out of\nBrownian randomization in presence of the electric field has been determined as\nthe third dominant mode. An analytical model based on discrete interactions of\nthe charged particle fluid domains explains the various behavioral aspects of\nsuch dispersions, as observed and validated from detailed experimental\nanalysis. The analysis is also predictive of the dominance and behavior of the\nthree modes with important nanocolloid parameters such as temperature and\nconcentration."
    },
    {
        "anchor": "Rapid Sampling of Stochastic Displacements in Brownian Dynamics\n  Simulations: We present a new method for sampling stochastic displacements in Brownian\nDynamics (BD) simulations of colloidal scale particles. The method relies on a\nnew formulation for Ewald summation of the Rotne-Prager-Yamakawa (RPY) tensor,\nwhich guarantees that the real-space and wave-space contributions to the tensor\nare independently symmetric and positive-definite for all possible particle\nconfigurations. Brownian displacements are drawn from a superposition of two\nindependent samples: a wave-space (far-field or long-ranged) contribution,\ncomputed using techniques from fluctuating hydrodynamics and non-uniform Fast\nFourier Transforms; and a real-space (near-field or short-ranged) correction,\ncomputed using a Krylov subspace method. The combined computational complexity\nof drawing these two independent samples scales linearly with the number of\nparticles. The proposed method circumvents the super-linear scaling exhibited\nby all known iterative sampling methods applied directly to the RPY tensor that\nresults from the power law growth of the condition number of tensor with the\nnumber of particles. Calculations for hard sphere dispersions and colloidal\ngels are illustrated and used to explore the role of microstructure on\nperformance of the algorithm. In practice, the logarithmic part of the\npredicted scaling is not observed and the algorithm scales linearly for up to 4\nmillion particles, obtaining speed ups of over an order of magnitude over\nexisting iterative methods, and making the cost of computing Brownian\ndisplacements comparable the cost of computing deterministic displacements in\nBD simulations. A high-performance implementation employing non-uniform fast\nFourier transforms implemented on graphics processing units and integrated with\nthe software package HOOMD-blue is used for benchmarking.",
        "positive": "Intermittent and continuos flows in granular piles: effects of\n  controlling the feeding height: Using a specially designed experimental set up, we have studied the so-called\ncontinuous to intermittent flow transition in sand piles confined in a\nHele-Shaw cell where the deposition height of the sand can be controlled.\nThrough systematic measurements varying the height and the input flow, we have\nestablished, for the first time, how the size of the pile at which the\ntransition takes place depends on the two parameters studied. The results\nobtained allows to explain, at least semi-quantitatively, the observations\ncommonly reported in the literature, carried out in experiments where the\ndeposition height is not controlled."
    },
    {
        "anchor": "The effect of boundary adaptivity on hexagonal ordering and bistability\n  in circularly confined quasi hard discs: The behaviour of materials under spatial confinement is sensitively dependent\non the nature of the confining boundaries. In two dimensions, confinement\nwithin a hard circular boundary inhibits the hexagonal ordering observed in\nbulk systems at high density. Using colloidal experiments and Monte Carlo\nsimulations, we investigate two model systems of quasi hard discs under\ncircularly symmetric confinement. The first system employs an adaptive circular\nboundary, defined experimentally using holographic optical tweezers. We show\nthat deformation of this boundary allows, and indeed is required for, hexagonal\nordering in the confined system. The second system employs a circularly\nsymmetric optical potential to confine particles without a physical boundary.\nWe show that, in the absence of a curved wall, near perfect hexagonal ordering\nis possible. We propose that the degree to which hexagonal ordering is\nsuppressed by a curved boundary is determined by the `strictness' of that wall.",
        "positive": "Interface-templated crystal growth in sodium dodecyl sulfate solutions\n  with NaCl: Many ionic surfactants, such as sodium dodecyl sulphate (SDS) crystallize out\nof solution if the temperature falls below the crystallization boundary. The\ncrystallization temperature is impacted by solution properties, and can be\ndecreased with the addition of salt. We have studied SDS crystallization a t\nthe liquid/vapor interfaces from solutions at high ionic strength (sodium\nchloride). We show that the surfactant crystals at the surface grow from\nadsorbed SDS molecules, as evidenced by the preferential orientation of the\ncrystals identified using grazing incidence X-ray diffraction. We find a unique\ntimescale f or the crystal growth from the evolution of structure, surface\ntension, and visual inspection, which can be controlled through varying the SDS\nor NaCl concentrations."
    },
    {
        "anchor": "Liquid Crystals with Patterned Molecular Orientation as an Electrolytic\n  Active Medium: Transport of fluids and particles at the microscale is an important theme\nboth in fundamental and applied science. One of the most successful approaches\nis to use an electric field, which requires the system to carry or induce\nelectric charges. We describe a versatile approach to generate electrokinetic\nflows by using a liquid crystal (LC) with surface-patterned molecular\norientation as an electrolyte. The surface patterning is produced by\nphoto-alignment. In the presence of an electric field, the spatially varying\norientation induces space charges that trigger flows of the LC. The active\npatterned LC electrolyte converts the electric energy into the LC flows and\ntransport of embedded particles of any type (fluid, solid, gaseous) along a\npredesigned trajectory, posing no limitation on the electric nature (charge,\npolarizability) of these particles and interfaces. The patterned LC electrolyte\nexhibits a quadratic field dependence of the flow velocities; it induces\npersistent vortices of controllable rotation speed and direction that are\nquintessential for micro- and nanoscale mixing applications.",
        "positive": "Shear instabilities in granular mixtures: Dynamical instabilities in fluid mechanics are responsible of a variety of\nimportant common phenomena, such as waves on the sea surface or Taylor vorteces\nin Couette flow. In granular media dynamical instabilities has just begun to be\ndiscovered. Here we show by means of molecular dynamics simulation the\nexistence of a new dynamical instability of a granular mixture under\noscillating horizontal shear, which leads to the formation of a striped pattern\nwhere the components are segregated. We investigate the properties of such a\nKelvin-Helmholtz like instability and show how it is connected to pattern\nformation in granular flow and segregation."
    },
    {
        "anchor": "Adsorbed films of three-patch colloids: Continuous and discontinuous\n  transitions between thick and thin films: We investigate numerically the role of spatial arrangement of the patches on\nthe irreversible adsorption of patchy colloids on a substrate. We consider\nspherical three-patch colloids and study the dependence of the kinetics on the\nopening angle between patches. We show that growth is suppressed below and\nabove minimum and maximum opening angles, revealing two absorbing phase\ntransitions between thick and thin film regimes. While the transition at the\nminimum angle is continuous, in the Directed Percolation class, that at the\nmaximum angle is clearly discontinuous. For intermediate values of the opening\nangle, a rough colloidal network in the Kardar-Parisi-Zhang universality class\ngrows indefinitely. The nature of the transitions was analyzed in detail by\nconsidering bond flexibility, defined as the dispersion of the angle between\nthe bond and the center of the patch. For the range of flexibilities considered\nwe always observe two phase transitions. However, the range of opening angles\nwhere growth is sustained increases with flexibility. At a tricritical\nflexibility, the discontinuous transition becomes continuous. The practical\nimplications of our findings and the relation to other nonequilibrium\ntransitions are discussed.",
        "positive": "Air, helium and water leakage in rubber O-ring seals with application to\n  syringes: We study the leakage of fluids (liquids or gases) in syringes with glass\nbarrel, steel plunger and rubber O-ring stopper. The leakrate depends on the\ninterfacial surface roughness and on the viscoelastic properties of the rubber.\nRandom surface roughness is produced by sandblasting the rubber O-rings. We\npresent a very simple theory for gas flow which takes into account both the\ndiffusive and ballistic flow. The theory shows that the interfacial fluid flow\n(leakage) channels are so narrow that the gas flow is mainly ballistic (the so\ncalled Knudsen limit). We compare the leakrate obtained using air and helium.\nFor barrels filled with water we observe no leakage even if leakage occurs for\ngases. We interpret this as resulting from capillary (Laplace pressure or\nsurface energy) effects."
    },
    {
        "anchor": "Microscopic Theory of Protein Folding Rates.I: Fine Structure of the\n  Free Energy Profile and Folding Routes from a Variational Approach: A microscopic theory of the free energy barriers and folding routes for\nminimally frustrated proteins is presented, greatly expanding on the\npresentation of the variational approach outlined previously [J. J. Portman, S.\nTakada, P. G. Wolynes, Phys. Rev. Lett. {\\bf 81}, 5237 (1998)]. We choose the\n$\\lambda$-repressor protein as an illustrative example and focus on how the\npolymer chain statistics influence free energy profiles and partially ordered\nensembles of structures. In particular, we investigate the role of chain\nstiffness on the free energy profile and folding routes. We evaluate the\napplicability of simpler approximations in which the conformations of the\nprotein molecule along the folding route are restricted to have residues that\nare either entirely folded or unfolded in contiguous stretches. We find that\nthe folding routes obtained from only one contiguous folded region corresponds\nto a chain with a much greater persistence length than appropriate for natural\nprotein chains, while the folding route obtained from two contiguous folded\nregions is able to capture the relatively folded regions calculated within the\nvariational approach. The free energy profiles obtained from the contiguous\nsequence approximations have larger barriers than the more microscopic\nvariational theory which is understood as a consequence of partial ordering.",
        "positive": "The Hydra String Method: A Novel Means to Explore Potential Energy\n  Surfaces and its Application to Granular Materials: Granular materials are a ubiquitous yet ill-understood class of media. Many\ndifferent approaches and techniques have been developed to understand the many\ncomplex behaviors they exhibit but none have been completely successful. We\npresent a novel means to understand granular materials, the Hydra String Method\n(HSM). This is an efficient and autonomous way to trawl an arbitrary potential\nenergy surface (or any similarly high dimensional function) that enumerates the\nsaddle points, minima, and minimum energy paths between them. In doing so, it\ncreates a reduced dimensional network representation of this function. We also\npresent a series of tests to choose optimized parameters for the application of\nthe HSM. We apply this to the potential energy function of a granular system\nconsisting of a bidisperse configuration of frictionless soft spheres. Future\nwork will make use of the found ensemble of transition pathways to\nstatistically predict the dynamics of a system of grains."
    },
    {
        "anchor": "Simple flexible polymers in a spherical cage: We report the results of Monte Carlo simulations investigating the effect of\na spherical confinement within a simple model for a flexible homopolymer. We\nuse the parallel tempering method combined with multi-histogram reweighting\nanalysis and multicanonical simulations to investigate thermodynamical\nobservables over a broad range of temperatures, which enables us to describe\nthe behavior of the polymer and to locate the freezing and collapse\ntransitions. We find a strong effect of the spherical confinement on the\nlocation of the collapse transition, whereas the freezing transition is hardly\neffected.",
        "positive": "Three-Dimensional Active Defect Loops: We describe the flows and morphological dynamics of topological defect lines\nand loops in three-dimensional active nematics and show, using theory and\nnumerical modelling, that they are governed by the local profile of the\norientational order surrounding the defects. Analysing a continuous span of\ndefect loop profiles, ranging from radial and tangential twist to wedge $\\pm\n1/2$ profiles, we show that the distinct geometries can drive material flow\nperpendicular or along the local defect loop segment, whose variation around a\nclosed loop can lead to net loop motion, elongation or compression of shape, or\nbuckling of the loops. We demonstrate a correlation between local curvature and\nthe local orientational profile of the defect loop, indicating dynamic coupling\nbetween geometry and topology. To address the general formation of defect loops\nin three dimensions, we show their creation via bend instability from different\ninitial elastic distortions."
    },
    {
        "anchor": "Separation of long DNA chains using non-uniform electric field: a\n  numerical study: We study migration of DNA molecules through a microchannel with a series of\nelectric traps controlled by an ac electric field. We describe the motion of\nDNA based on Brownian dynamics simulations of a beads-spring chain. Our\nsimulation demonstrates that the chain captured by an electrode escapes from\nthe binding electric field due to thermal fluctuation. We find that the\nmobility of chain would depend on the chain length; the mobility sharply\nincreases when the length of a chain exceeds a critical value, which is\nstrongly affected by the amplitude of the applied ac field. Thus we can adjust\nthe length regime, in which this microchannel well separates DNA molecules,\nwithout changing the structure of the channel. We also present a theoretical\ninsight into the relation between the critical chain length and the field\namplitude.",
        "positive": "Initial rigid response and softening transition of highly stretchable\n  kirigami sheet materials: We study, experimentally and theoretically, the mechanical response of sheet\nmaterials on which line cracks or cuts are arranged in a simple pattern. Such\nsheet materials, often called kirigami (the Japanese words, kiri and gami,\nstand for cut and paper, respectively), demonstrate a unique mechanical\nresponse promising for various engineering applications such as stretchable\nbatteries: kirigami sheets possess a mechanical regime in which sheets are\nhighly stretchable and very soft compared with the original sheets without line\ncracks, by virtue of out-of-plane deformation. However, this regime starts\nafter a transition from an initial stiff regime governed by in-plane\ndeformation. In other words, the softness of the kirigami structure emerges as\na result of a transition from the two-dimensional to three-dimensional\ndeformation, i.e., from stretching to bending. We clarify the physical origins\nof the transition and mechanical regimes, which are revealed to be governed by\nsimple scaling laws. The results could be useful for controlling and designing\nthe mechanical response of sheet materials including cell sheets for medical\nregeneration and relevant to the development of materials with tunable\nstiffness and mechanical force sensors."
    },
    {
        "anchor": "Evaporation-driven ring and film deposition from colloidal droplets: Evaporating suspensions of colloidal particles lead to the formation of a\nvariety of patterns, ranging from a left-over ring of a dried coffee drop to\nuniformly distributed solid pigments left behind wet paint. To characterize the\ntransition between single rings, multiple concentric rings, broad bands, and\nuniform deposits, we investigate the dynamics of a drying droplet via a\nmultiphase model of colloidal particles in a solvent. Our theory couples the\ninhomogeneous evaporation at the evolving droplet interface to the dynamics\ninside the drop, i.e. the liquid flow, local variations of the particle\nconcentration, and the propagation of the deposition front where the solute\nforms an incompressible porous medium at high concentrations. A dimensionless\nparameter combining the capillary number and the droplet aspect ratio captures\nthe formation conditions of different pattern types.",
        "positive": "Mode-coupling theory of the glass transition for confined fluids: We present a detailed derivation of a microscopic theory for the glass\ntransition of a liquid enclosed between two parallel walls relying on a\nmode-coupling approximation. This geometry lacks translational invariance\nperpendicular to the walls, which implies that the density profile and the\ndensity-density correlation function depends explicitly on the distances to the\nwalls. We discuss the residual symmetry properties in slab geometry and\nintroduce a symmetry adapted complete set of two-point correlation functions.\nSince the currents naturally split into components parallel and perpendicular\nto the walls the mathematical structure of the theory differs from the\nestablished mode-coupling equations in bulk. We prove that the equations for\nthe nonergodicity parameters still display a covariance property similar to\nbulk liquids."
    },
    {
        "anchor": "Stochastic Resonance in an Extended FitzHugh-Nagumo System: the Role of\n  Selective Coupling: Here we present a study of stochastic resonance in an extended\nFitzHugh-Nagumo system with a field dependent activator diffusion. We show that\nthe system response (here measured through the output signal-to-noise ratio) is\nenhanced due to the particular form of the non-homogeneous coupling. Such a\nresult supports previous ones obtained in a simpler scalar reaction-diffusion\nsystem and shows that such an enhancement, induced by the field dependent\ndiffusion -or selective coupling-, is a robust phenomenon.",
        "positive": "Symmetry Plays a Key Role in the Erasing of Patterned Surface Features: We report on how the relaxation of patterns prepared on a thin film can be\ncontrolled by manipu- lating the symmetry of the initial shape. The validity of\na lubrication theory for the capillary-driven relaxation of surface profiles is\nverified by atomic force microscopy measurements, performed on films that were\npatterned using focused laser spike annealing. In particular, we observe that\nthe shape of the surface profile at late times is entirely determined by the\ninitial symmetry of the perturba- tion, in agreement with the theory. Moreover,\nin this regime the perturbation amplitude relaxes as a power-law in time, with\nan exponent that is also related to the initial symmetry. The results have\nrelevance in the dynamical control of topographic perturbations for\nnanolithography and high density memory storage."
    },
    {
        "anchor": "Feshbach Resonances in Fermionic Lithium-6: Feshbach resonances in lithium-6 were experimentally studied and\ntheoretically analyzed. In addition to two previously known s-wave resonances,\nwe found three p-wave resonances. Four of these resonances are narrow and yield\na precise value of the singlet scattering length, but do not allow us to\naccurately predict the location of the broad resonance near 83 mT. Its position\nwas previously measured in a molecule-dissociation experiment for which we,\nhere, discuss systematic shifts.",
        "positive": "Electrically tunable selective reflection of light from ultraviolet to\n  visible and infrared by heliconical cholesterics: Cholesteric liquid crystals with helicoidal molecular architecture are known\nfor their ability to selectively reflect light with the wavelength that is\ndetermined by the periodicity of molecular orientations. Here we demonstrate\nthat by using a cholesteric with oblique helicoidal(heliconical) structure, as\nopposed to the classic right-angle helicoid, one can vary the wavelength of\nselectively reflected light in a broad spectral range, from ultraviolet to\nvisible and infrared (360-1520 nm for the same chemical composition) by simply\nadjusting the electric field applied parallel to the helicoidal axis. The\neffect exists in a wide temperature range (including the room temperatures) and\nthus can enable many applications that require dynamically controlled\ntransmission and reflection of electromagnetic waves, from energy-saving smart\nwindows to tunable organic lasers, reflective color display, and transparent\nsee-through displays."
    },
    {
        "anchor": "Hydrodynamic theory of two-dimensional incompressible polar active\n  fluids with quenched and annealed disorder: We study the moving phase of two-dimensional (2D) incompressible polar active\nfluids in the presence of both quenched and annealed disorder. We show that\nlong-range polar order persists even in this defect-ridden two-dimensional\nsystem. We obtain the large-distance, long-time scaling laws of the velocity\nfluctuations using three distinct dynamic renormalization group schemes. These\nare an uncontrolled one-loop calculation in exactly two dimensions, and two\n$d=(d_c-\\epsilon)$-expansions to $O(\\epsilon)$, obtained by two different\nanalytic continuations of our 2D model to higher spatial dimensions: a ``hard\"\ncontinuation which has $d_c={7\\over 3}$, and a ``soft\" continuation with\n$d_c={5\\over 2}$. Surprisingly, the quenched and annealed parts of the velocity\ncorrelation function have the same anisotropy exponent and the relaxational and\npropagating parts of the dispersion relation have the same dynamic exponent in\nthe nonlinear theory even though they are distinct in the linearized theory.\nThis is due to anomalous hydrodynamics. Furthermore, all three renormalization\nschemes yield very similar values for the universal exponents, and, therefore,\nwe expect the numerical values we predict for them to be highly accurate.",
        "positive": "Piezo-Electric Shear Rheometry: Further developments in experimental\n  implementation and data extraction: The Piezo-electric Shear Gauge (PSG) [Christensen & Olsen, Rev. Sci. Instrum.\n66, 5019, 1995] is a rheometric technique developed to measure the complex\nshear modulus of viscous liquids near their glass transition temperature. We\nreport recent advances to the PSG technique: 1) The data extraction procedure\nis optimized which extends the upper limit of the frequency range of the method\nto between 50 and 70 kHz. 2) The measuring cell is simplified to use only one\npiezo-electric ceramic disc instead of three. We present an implementation of\nthis design intended for liquid samples. Data obtained with this design\nrevealed that a soft extra spacer is necessary to allow for thermal contraction\nof the sample in the axial direction. Model calculations show that flow in the\nradial direction is hindered by the confined geometry of the cell when the\nliquid becomes viscous upon cooling. The method is especially well-suited for\n-- but not limited to -- glassy materials."
    },
    {
        "anchor": "Mechanics of cell crawling by means of force-free cyclic motion: The mechanics of crawling cells on a substrate is investigated by using a\nminimal model that satisfies the force-free condition. A cell is described by\ntwo subcellular elements connected by a linear actuator that changes the length\nof the cell cyclically in time, together with periodic alternation of adhesive\ncharacters at the interface between the cell and the substrate. Here the key\nmodel parameters are the phase shifts between the elongation of the actuator\nand the alternation of the adhesion of the two elements. We emphasize that the\nphase shifts determine not only the efficiency of the crawling motion but also\nits direction.",
        "positive": "A Modified Model for Static Friction of a Soft and Hard Solid Interface: We present a modified model based on shear rate and aging time dependent\nstatic friction between a soft solid such as gelatin hydrogel and a hard\nsurface for instance glass surface. Earlier the model for static friction\n(Juvekar and Singh, 2016) considered only the bond rupture process as a result,\nthe friction model over predicts the static friction in the experiment. The\nfriction model now takes into account both formation and rupture of molecular\nchains at the sliding interface. It is also assumed that age of the newly\nformed bonds during the rupture process is the same as the aging time. As a\nresult, the model predicts quite well the experimental data and thus\nhighlighting the significance of bond formation in static friction. Moreover,\nit is also observed that residual stress has no effect on static strength."
    },
    {
        "anchor": "Macroscopic forces in inhomogeneous polyelectrolyte solutions: In this paper, we present a self-consistent field theory of macroscopic\nforces in spatially inhomogeneous flexible chain polyelectrolyte solutions. We\nderive an analytical expression for a stress tensor which consists of three\nterms: isotropic hydrostatic stress, electrostatic (Maxwell) stress, and stress\nrising from conformational entropy of polymer chains -- conformational stress.\nWe apply our theory to the description of polyelectrolyte solutions confined in\na conductive slit nanopore and observe anomalous behavior of disjoining\npressure and electric differential capacitance.",
        "positive": "Stress relaxation through crosslink unbinding in cytoskeletal networks: The mechanical properties of cells are dominated by the cytoskeleton, an\ninterconnected network of long elastic filaments. The connections between the\nfilaments are provided by crosslinking proteins, which constitute, next to the\nfilaments, the second important mechanical element of the network. An important\naspect of cytoskeletal assemblies is their dynamic nature, which allows\nremodeling in response to external cues. The reversible nature of crosslink\nbinding is an important mechanism that underlies these dynamical processes.\nHere, we develop a theoretical model that provides insight into how the\nmechanical properties of cytoskeletal networks may depend on their underlying\nconstituting elements. We incorporate three important ingredients: nonaffine\nfilament deformations in response to network strain; interplay between filament\nand crosslink mechanical properties; reversible crosslink (un)binding in\nresponse to imposed stress. With this we are able to self-consistently\ncalculate the nonlinear modulus of the network as a function of deformation\namplitude and crosslink as well as filament stiffnesses. During loading\ncrosslink unbinding processes lead to a relaxation of stress and therefore to a\nreduction of the network modulus and eventually to network failure, when all\ncrosslink are unbound. This softening due to crosslink unbinding generically\ncompetes with an inherent stiffening response, which may either be due to\nfilament or crosslink nonlinear elasticity."
    },
    {
        "anchor": "The Narrow Pulse Approximation and long length scale determination in\n  xenon gas diffusion NMR studies of model porous media: We report a systematic study of xenon gas diffusion NMR in simple model\nporous media: random packs of mono-sized glass beads, and focus on three\nspecific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion\nof spins on the order of the pore dimensions during the application of the\ndiffusion encoding gradient pulses in a PGSE experiment (breakdown of the\n'narrow pulse approximation' and imperfect background gradient cancellation),\n(ii) the ability to derive long-length scale structural information, and (iii)\neffects of finite sample size. We find that the time-dependent diffusion\ncoefficient, D(t), of the imbibed xenon gas at short diffusion times in small\nbeads is significantly affected by the gas pressure. In particular, as\nexpected, we find smaller deviations between measured D(t) and theoretical\npredictions as the gas pressure is increased, resulting from reduced diffusion\nduring the application of the gradient pulse. The deviations are then\ncompletely removed when water D(t) is observed in the same samples. The use of\ngas also allows us to probe D(t) over a wide range of length scales, and\nobserve the long-time asymptotic limit which is proportional to the inverse\ntortuosity of the sample, as well as the diffusion distance where this limit\ntakes effect (~ 1 - 1.5 bead diameters). The Pade approximation can be used as\na reference for expected xenon D(t) data between the short and long time\nlimits, allowing us to explore deviations from the expected behaviour at\nintermediate times as a result of finite sample size effects. Finally, the\napplication of the Pade interpolation between the long and short time\nasymptotic limits yields a fitted length scale (the \"Pade length\"), which is\nfound to be ~ 0.13b for all bead packs, where b is the bead diameter.",
        "positive": "Structure of interacting aggregates of silica nanoparticles in a polymer\n  matrix: Small-angle scattering and Reverse Monte-Carlo simulations: Reinforcement of elastomers by colloidal nanoparticles is an important\napplication where microstructure needs to be understood - and if possible\ncontrolled - if one wishes to tune macroscopic mechanical properties. Here the\nthree-dimensional structure of big aggregates of nanometric silica particles\nembedded in a soft polymeric matrix is determined by Small Angle Neutron\nScattering. Experimentally, the crowded environment leading to strong\nreinforcement induces a strong interaction between aggregates, which generates\na prominent interaction peak in the scattering. We propose to analyze the total\nsignal by means of a decomposition in a classical colloidal structure factor\ndescribing aggregate interaction and an aggregate form factor determined by a\nReverse Monte Carlo technique. The result gives new insights in the shape of\naggregates and their complex interaction in elastomers. For comparison, fractal\nmodels for aggregate scattering are also discussed."
    },
    {
        "anchor": "Influence of boundary conditions on 2-fluid Systems under horizontal\n  vibration: This paper is concerned with 2-phase systems under vibration in gravity\ncondition, when the gravity is perpendicular to the direction of vibration. It\ntries and demonstrates that, even in such a restricted case, the patterns which\ncan be formed are very sensitive to the cell shape, to the boundary conditions\nand to the direction and the mode of vibration, i.e. linear, rotational,...\nPacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn",
        "positive": "From liquid to solid bonding in cohesive granular media: We study the transition of a granular packing from liquid to solid bonding in\nthe course of drying. The particles are initially wetted by a liquid brine and\nthe cohesion of the packing is ensured by capillary forces, but the\ncrystallization of the solute transforms the liquid bonds into partially\ncemented bonds. This transition is evidenced experimentally by measuring the\ncompressive strength of the samples at regular intervals of times. Our\nexperimental data reveal three regimes: 1) Up to a critical degree of\nsaturation, no solid bonds are formed and the cohesion remains practically\nconstant; 2) The onset of cementation occurs at the surface and a front spreads\ntowards the center of the sample with a nonlinear increase of the cohesion; 3)\nAll bonds are partially cemented when the cementation front reaches the center\nof the sample, but the cohesion increases rapidly due to the consolidation of\ncemented bonds. We introduce a model based on a parametric cohesion law at the\nbonds and a bond crystallization parameter. This model predicts correctly the\nphase transition and the relation between microscopic and macroscopic cohesion."
    },
    {
        "anchor": "Simple dynamical model with history dependence for a sandpile experiment: A lattice dynamics model is proposed for the history dependence observed in\nsandpile experiments. The dependence of the stress distribution on the\npreparation of the sandpile is explained as a dependence of certain attractors\non the preparation of the system. The model has three phases, but the history\ndependence is shown to exist only in the phase where a perturbation is\namplified selectively rather than globally when propagating in the downflow\ndirection. The condition for this history dependence is given in terms of the\nspatial Lyapunov exponent.",
        "positive": "Electrowetting of a nano-suspension on a soft solid: The wetting of solid surfaces can be manoeuvred by altering the energy\nbalance at the interfacial region. While electric field acts favourably to\nspread a droplet on a rigid surface, this tendency may be significantly\nsuppressed over soft surfaces, considering a part of the interfacial energy\nbeing utilized to deform the solid elastically by capillary forces. Here, we\nbring out a unique mechanism by virtue of which addition of nano-particles to\nthe droplet brings in a favourable recovery of the electro-spreading\ncharacteristics of a soft surface, by realizing an alteration in the effective\ndielectric constant of the interfacial region. Our experiments further\ndemonstrate that this mechanism ceases to be operative beyond a threshold\nvolume fraction of the particle suspension, due to inevitable contact line\npinning. We also develop a theory to explain our experimental observations. Our\nfindings provide a non-contact mechanism for meniscus spreading and droplet\ncontrol, bearing far-reaching implications in biology and engineering."
    },
    {
        "anchor": "Colloids in Two-Dimensional Active Nematics: Conformal Cogs and\n  Controllable Spontaneous Rotation: A major challenge in the study of active systems is to harness their\nnon-equilibrium dynamics into useful work. We address this by showing how to\ndesign colloids with controllable spontaneous propulsion or rotation when\nimmersed in active nematics. This is illustrated for discs with tilted\nanchoring and chiral cogs, for which we determine the nematic director through\nconformal mappings. Our analysis identifies two regimes of behaviour for chiral\ncogs: orientation-dependent handedness and persistent active rotation. Finally,\nwe provide design principles for active nematic colloids to achieve desired\nrotational dynamics.",
        "positive": "Diffusion of Globular Macromolecules in Liquid Crystals of Colloidal\n  Cuboids: Macromolecular diffusion in dense colloidal suspensions is an intriguing\ntopic of interdisciplinary relevance in Science and Engineering. While\nsignificant efforts have been undertaken to establish the impact of crowding on\nthe dynamics of macromolecules, less clear is the role played by long-range\nordering. In this work, we perform Dynamic Monte Carlo simulations to assess\nthe importance of ordered crowding on the diffusion of globular macromolecules,\nhere modelled as spherical tracers, in suspensions of colloidal cuboids. We\nfirst investigate the diffusion of such guest tracers in very weakly ordered\nhost phases of cuboids and, by increasing density above the\nisotropic-to-nematic phase boundary, study the influence of long-range\norientational ordering imposed by the occurrence of liquid-crystalline phases.\nTo this end, we analyse a spectrum of dynamical properties that clarify the\nexistence of slow and fast tracers and the extent of deviations from Gaussian\nbehaviour. Our results unveil the existence of randomly oriented clusters of\ncuboids that display a relatively large size in dense isotropic phases, but are\nbasically absent in the nematic phase. We believe that these clusters are\nresponsible for a pronounced non-Gaussian dynamics that is much weaker in the\nnematic phase, where orientational ordering smooths out such structural\nheterogeneities."
    },
    {
        "anchor": "Brownian motion of a circle swimmer in a harmonic trap: We study the dynamics of a Brownian circle swimmer with a time-dependent\nself-propulsion velocity in an external temporally varying harmonic potential.\nFor several situations, the noise-free swimming paths, the noise-averaged mean\ntrajectories, and the mean square displacements are calculated analytically or\nby computer simulation. Based on our results, we discuss optimal swimming\nstrategies in order to explore a maximum spatial range around the trap center.\nIn particular, we find a resonance situation for the maximum escape distance as\na function of the various frequencies in the system. Moreover, the influence of\nthe Brownian noise is analyzed by comparing noise-free trajectories at zero\ntemperature with the corresponding noise-averaged trajectories at finite\ntemperature. The latter reveal various complex self-similar spiral or\nrosette-like patterns. Our predictions can be tested in experiments on\nartificial and biological microswimmers under dynamical external confinement.",
        "positive": "Magnetic chains: From self-buckling to self-assembly: Spherical neodymium-iron-boron magnets are perman-ent magnets that can be\nassembled into a variety of structures due to their high magnetic strength. A\none-dimensional chain of these magnets responds to mechanical loadings in a\nmanner reminiscent of an elastic rod. We investigate the macroscopic mechanical\nproperties of assemblies of ferromagnetic spheres by considering chains, rings,\nand chiral cylinders of magnets. Based on energy estimates and simple\nexperiments, we introduce an effective magnetic bending stiffness for a chain\nof magnets and show that, used in conjunction with classic results for elastic\nrods, it provides excellent estimates for the buckling and vibration dynamics\nof magnetic chains. We then use this estimate to understand the dynamic\nself-assembly of a cylinder from an initially straight chain of magnets."
    },
    {
        "anchor": "The interplay between screening properties and colloid anisotropy:\n  towards a reliable pair potential for disc-like charged particles: The electrostatic potential of a highly charged disc (clay platelet) in an\nelectrolyte is investigated in detail. The corresponding non-linear\nPoisson-Boltzmann (PB) equation is solved numerically, and we show that the\nfar-field behaviour (relevant for colloidal interactions in dilute suspensions)\nis exactly that obtained within linearized PB theory, with the surface boundary\ncondition of a uniform potential. The latter linear problem is solved by a new\nsemi-analytical procedure and both the potential amplitude (quantified by an\neffective charge) and potential anisotropy coincide closely within PB and\nlinearized PB, provided the disc bare charge is high enough. This anisotropy\nremains at all scales; it is encoded in a function that may vary over several\norders of magnitude depending on the azimuthal angle under which the disc is\nseen. The results allow to construct a pair potential for discs interaction,\nthat is strongly orientation dependent.",
        "positive": "Corners in soft solids behave as defects in crystals: All phases of matter, solid, liquid or gas, present some excess energy,\ncompared to their bulk, at their interfaces with other materials. This excess\nof energy, known as the surface energy, is a fundamental property of matter and\nis involved in virtually all interface problems in science, from the shape of\nbubbles, crystals and biological cells to the delicate motion of some insects\non water or the fluttering of red blood cells. Because of their high cohesive\ninternal energies, the surface energies of solids differ fundamentally from\nthose of fluids and depend on the solid deformations. This effect, known as the\nShuttleworth effect, is well established for metals but is highly debated for\namorphous materials such as glasses, elastomers or biological tissues with\nrecent experimental results yielding strictly opposite conclusions with regards\nto its very existence. Using a combination of analytical results and numerical\nsimulations, we show in this paper that those seemingly opposite results can be\nreconciled due to the existence of an analog of the Peach-Koehler force acting\non the elastocapillary ridge and conclude that: i) there is no large\nShuttleworth effect in soft elastomers and ii) the Neumann construction does\nnot hold in elastowetting."
    },
    {
        "anchor": "Deformation-Driven Diffusion and Plastic Flow in Two-Dimensional\n  Amorphous Granular Pillars: We report a combined experimental and simulation study of deformation-induced\ndiffusion in compacted two-dimensional amorphous granular pillars, in which\nthermal fluctuations play negligible role. The pillars, consisting of\nbidisperse cylindrical acetal plastic particles standing upright on a\nsubstrate, are deformed uniaxially and quasistatically by a rigid bar moving at\na constant speed. The plastic flow and particle rearrangements in the pillars\nare characterized by computing the best-fit affine transformation strain and\nnon-affine displacement associated with each particle between two stages of\ndeformation. The non-affine displacement exhibits exponential crossover from\nballistic to diffusive behavior with respect to the cumulative deviatoric\nstrain, indicating that in athermal granular packings, the cumulative\ndeviatoric strain plays the role of time in thermal systems and drives\neffective particle diffusion. We further study the size-dependent deformation\nof the granular pillars by simulation, and find that different-sized pillars\nfollow self-similar shape evolution during deformation. In addition, the yield\nstress of the pillars increases linearly with pillar size. Formation of\ntransient shear lines in the pillars during deformation becomes more evident as\npillar size increases. The width of these elementary shear bands is about twice\nthe diameter of a particle, and does not vary with pillar size.",
        "positive": "Stability of gap solitons in a Bose-Einstein condensate: We analyze the dynamical stability of gap solitons formed in a quasi\none-dimensional Bose-Einstein condensate in an optical lattice. Using two\ndifferent numerical methods we show that, under realistic assumptions for\nexperimental parameters, a gap soliton is stable only in a truly\none-dimensional situation. In two and three dimensions resonant transverse\nexcitations lead to dynamical instability. The time scale of the decay is\nnumerically calculated and shown to be large compared to the characteristic\ntime scale of solitons for realistic physical parameters."
    },
    {
        "anchor": "Tagged particle in a sheared suspension: effective temperature\n  determines density distribution in a slowly varying external potential beyond\n  linear response: We consider a sheared colloidal suspension under the influence of an external\npotential that varies slowly in space in the plane perpendicular to the flow\nand acts on one selected (tagged) particle of the suspension. Using a\nChapman-Enskog type expansion we derive a steady state equation for the tagged\nparticle density distribution. We show that for potentials varying along one\ndirection only, the tagged particle distribution is the same as the equilibrium\ndistribution with the temperature equal to the effective temperature obtained\nfrom the violation of the Einstein relation between the self-diffusion and\ntagged particle mobility coefficients. We thus prove the usefulness of this\neffective temperature for the description of the tagged particle behavior\nbeyond the realm of linear response. We illustrate our theoretical predictions\nwith Brownian dynamics computer simulations.",
        "positive": "Rheology, Structure and Dynamics of Colloid-Polymer Mixtures: from\n  Liquids to Gels: We investigated the viscoelastic properties of colloid-polymer mixtures at\nintermediate colloid volume fraction and varying polymer concentrations,\nthereby tuning the attractive interactions. Within the examined range of\npolymer concentrations, the samples ranged from fluids to gels. Already in the\nliquid phase the viscoelastic properties significantly changed when approaching\nthe gelation boundary, indicating the formation of clusters and transient\nnetworks. This is supported by an increasing correlation length of the density\nfluctuations, observed by static light scattering and microscopy. At the same\ntime, the correlation function determined by dynamic light scattering\ncompletely decays, indicating the absence of dynamical arrest. Upon increasing\nthe polymer concentration beyond the gelation boundary, the rheological\nproperties changed qualitatively again, now they are consistent with the\nformation of colloidal gels. Our experimental results, namely the location of\nthe gelation boundary as well as the elastic (storage) and viscous (loss)\nmoduli, are compared to different theoretical models. These include\nconsideration of the escape time as well as predictions for the viscoelastic\nmoduli based on scaling relations and Mode Coupling Theories (MCT)."
    },
    {
        "anchor": "The Parental Active Model: a unifying stochastic description of\n  self-propulsion: We propose a new overarching model for self-propelled particles that flexibly\ngenerates a full family of \"descendants\". The general dynamics introduced in\nthis paper, which we denote as \"parental\" active model (PAM), unifies two\nspecial cases commonly used to describe active matter, namely active Brownian\nparticles (ABPs) and active Ornstein-Uhlenbeck particles (AOUPs). We thereby\ndocument the existence of a deep and close stochastic relationship between\nthem, resulting in the subtle balance between fluctuations in the magnitude and\ndirection of the self-propulsion velocity. Besides illustrating the relation\nbetween these two common models, the PAM can generate additional offspring,\ninterpolating between ABP and AOUP dynamics, that could provide more suitable\nmodels for a large class of living and inanimate active matter systems,\npossessing characteristic distributions of their self-propulsion velocity. Our\ngeneral model is evaluated in the presence of a harmonic external confinement.\nFor this reference example, we present a two-state phase diagram which sheds\nlight on the transition in the shape of the positional density distribution,\nfrom a unimodal Gaussian for AOUPs to a Mexican-hat-like profile for ABPs.",
        "positive": "Propagation of active nematic-isotropic interfaces on substrates: Motivated by results for the propagation of active-passive interfaces of\nbacterial Serratia marcescens swarms [Nat. Comm., 9, 5373 (2018)] we use a\nhydrodynamic multiphase model to investigate the propagation of interfaces of\nactive nematics on substrates. We characterize the active nematic phase of the\nmodel and discuss its description of the statistical dynamics of the swarms. We\nshow that the velocicity correlation functions and the energy spectrum of the\nactive turbulent phase of the model scale with the active length, for a range\nof activities. In addition, the energy spectrum exhibits two power-law regimes\nwith exponents close to those reported for other models and bacterial swarms.\nAlthough the exponent of the rising branch of the spectrum (small wavevector)\nappears to be independent of the activity, the exponent of the decay changes\nwith activity systematically, albeit slowly. We characterize also the\npropagation of circular and flat active-passive interfaces. We find that the\nclosing time of the circular passive domain decays quadratically with the\nactivity and that the structure factor of the flat interface is similar to that\nreported for swarms, with an activity dependent exponent. Finally, the effect\nof the substrate friction was investigated. We found an activity dependent\nthreshold, above which the turbulent active nematic forms isolated islands that\nshrink until the system becomes isotropic and below which the active nematic\nexpands, with a well defined propagating interface. The interface may be\nstopped by a fricion gradient."
    },
    {
        "anchor": "Identifying structural signatures of shear banding in model polymer\n  nanopillars: Amorphous solids are critical in the design and production of nanoscale\ndevices, but under strong confinement these materials exhibit changes in their\nmechanical properties which are not well understood. Phenomenological models\nexplain these properties by postulating an underlying defect structure in these\nmaterials but do not detail the microscopic properties of these defects. Using\nmachine learning methods, we identify mesoscale defects that lead to shear\nbanding in polymer nanopillars well below the glass transition temperature as a\nfunction of pillar diameter. Our results show that the primary structural\nfeatures responsible for shear banding on this scale are fluctuations in the\ndiameter of the pillar. Surprisingly, these fluctuations are quite small\ncompared to the diameter of the pillar, less than half of a particle diameter\nin size. At intermediate pillar diameters, we find that these fluctuations tend\nto concentrate along the minor axis of shear band planes. We also see the\nimportance of mean softness as a classifier of shear banding grow as a function\nof pillar diameter. Softness is a new field that characterizes local structure\nand is highly correlated with particle-level dynamics such that softer\nparticles are more likely to rearrange. This demonstrates that softness, a\nquantity that relates particle-level structure to dynamics on short time and\nlength scales, can predict large time and length scale phenomena related to\nmaterial failure.",
        "positive": "Role of the ratio of biopolyelectrolyte persistence length to\n  nanoparticle size in the structural tuning of electrostatic complexes: Aggregation of nanoparticles of given size $R$ induced by addition of a\npolymer strongly depends on its degree of rigidity. This is shown here on a\nlarge variety of silica nanoparticle self-assemblies obtained by electrostatic\ncomplexation with carefully selected oppositely charged bio-polyelectrolytes of\ndifferent rigidity. The effective rigidity is quantified by the total\npersistence length $L_T$ representing the sum of the intrinsic ($L_p$) and\nelectrostatic ($L_e$) polyelectrolyte persistence length, which depends on the\nscreening, i.e., on ionic strength due to counter-ions and external salt\nconcentrations. We experimentally show for the first time that the ratio L T /R\nis the main tuning parameter that controls the fractal dimension D f of the\nnanoparticles self-assemblies, which is determined using small-angle neutron\nscattering: (i) For $L_T /R<0.3$ (obtained with flexible poly-L-lysine in the\npresence of an excess of salt), chain flexibility promotes easy wrapping around\nnanoparticles in excess hence ramified structures with $D_f \\sim 2$. (ii) For\n$0.3<L_T /R\\le1$ (semiflexible chitosan or hyaluronan complexes), chain\nstiffness promotes the formation of one-dimensional nanorods (in excess of\nnanoparticles), in good agreement with computer simulations. (iii) For $L_T\n/R>1$, $L_e$ is strongly increased due to the absence of salt and repulsions\nbetween nanoparticles cannot be compensated by the polyelectrolyte wrapping,\nwhich allow a spacing between nanoparticles and the formation of one\ndimensional pearl necklace complexes. (iv) Finally, electrostatic 2 screening,\ni.e. ionic strength, turned out to be a reliable way of controlling $D_f$ and\nthe phase diagram behavior. It finely tunes the short-range interparticle\npotential, resulting in larger fractal dimensions at higher ionic strength."
    },
    {
        "anchor": "Spontaneous autophoretic motion of isotropic particles: Suspended colloidal particles interacting chemically with a solute are able\nto self-propel by autophoretic motion when they are asymmetrically patterned\n(Janus colloids). Here we demonstrate that the chemical anisotropy is not a\nnecessary condition to achieve locomotion. The non linear interplay between\nsurface osmotic flows and solute advection can produce spontaneous, and\nself-sustained motion of isotropic particles. We solve, for a spherical\nparticle, the classical nonlinear autophoretic theoretical framework at\narbitrary P\\'eclet number. For a given set of material parameters, there exists\na critical particle size, or equivalently a critical Peclet number, above which\nspontaneous autophoretic motion occurs. The flow induced by the particle\nfurther displays a hierarchy of instabilities associated with quantized\ncritical Peclet numbers. Using numerical solutions of the full (unsteady)\ndiffusiophoretic problem we confirm our analytical predictions and show that,\nabove the instability threshold, the isotropic particles reach a steady\nswimming state with broken front-back symmetry in the concentration field and\nthe hydrodynamic signature of a \"pusher\" swimmer. This instability to\npropulsion could be relevant to the high-throughput production of\nself-propelled particles.",
        "positive": "Comment on \"Solving the mystery of booming sand dunes\": We show here that the standard physical model used by Vriend et al. to\nanalyse seismograph data, namely a non-dispersive bulk propagation, does not\napply to the surface layer of sand dunes. According to several experimental,\ntheoretical and field results, the only possible propagation of sound waves in\na dry sand bed under gravity is through an infinite, yet discrete, number of\ndispersive surface modes. Besides, we present a series of evidences, most of\nwhich have already been published in the literature, that the frequency of\nbooming avalanches is not controlled by any resonance as argued in this\narticle. In particular, plotting the data provided by Vriend et al. as a table,\nit turns out that they do not present any correlation between the booming\nfrequency and their estimate of the resonant frequency."
    },
    {
        "anchor": "Influence of Inter-Layer Exchanges on Vorticity-Aligned Colloidal String\n  Assembly in a Simple Shear Flow: Hard spheres in Newtonian fluids serve as paradigms for Non-Newtonian\nmaterials phenomena exhibited by colloidal suspensions. A recent experimental\nstudy (Cheng et al. 2011 Science, 333, 1276) showed that upon application of\nshear to such a system, the particles form string-like structures aligned in\nthe vorticity direction. We explore the mechanism underlying this\nout-of-equilibrium organization with Steered Transition Path Sampling, which\nallows us to bias the Brownian contribution to rotations of close pairs of\nparticles and alter the dynamics of the suspension in a controlled fashion. Our\nresults show a strong correlation between the string structures and the\nrotation dynamics. Specifically, the simulations show that accelerating the\nrotations of close pairs of particles, not increasing their frequency, favors\nformation of the strings. This insight delineates the roles of hydrodynamics,\nBrownian motion, and particle packing, and, in turn, informs design strategies\nfor controlling the assembly of large-scale particle structures.",
        "positive": "Hierarchical geometries and adhesion: Bio-inspired designs for stiff\n  interfaces: Throughout biology, hierarchy is a recurrent theme in the geometry of\nstructures where strength is achieved with minimal use of material. Acting over\nvast timescales, evolution has brought about beautiful solutions to problems of\noptimisation that are only now being understood and incorporated into\nengineering design. One particular example of this hierarchy is found in the\njunction between stiff keratinised material and the soft biological matter\nwithin the hooves of ungulates. Using this biological interface as a design\nmotif, we investigate the role of hierarchy in the creation of a stiff, robust\ninterface between two materials. We show that through hierarchical design one\ncan manipulate the scaling laws relating constituent material stiffness and\noverall interface stiffness under both shear and tension loading. Furthermore,\nwe uncover a cascade of scaling laws for the higher order structure and link\ntheir origin with competing deformation modes within the structure. We\ndemonstrate that when joining two materials of different stiffness, under shear\nor tension, hierarchical geometries are linked with beneficial mechanical\nproperties."
    },
    {
        "anchor": "Role of normal stress in the creep dynamics and failure of a biopolymer\n  gel: We investigate the delayed rupture of biopolymer gels under a constant shear\nload by simultaneous dynamic light scattering and rheology measurements. We\nunveil the crucial role of normal stresses built up during gelation: all\nsamples that eventually fracture self-weaken during the gelation process, as\nrevealed by a partial relaxation of the normal stress concomitant to a burst of\nmicroscopic plastic rearrangements. Upon applying a shear stress, weakened gels\nexhibit in the creep regime distinctive signatures in their microscopic\ndynamics, which anticipate macroscopic fracture by up to thousands of seconds.\nThe dynamics in fracturing gels are faster than those of non-fracturing gels\nand exhibit large spatio-temporal fluctuations. A spatially localized region\nwith significant plasticity eventually nucleates, expands progressively, and\nfinally invades the whole sample triggering macroscopic failure.",
        "positive": "Phase behavior of a nematic liquid crystal in contact with a chemically\n  and geometrically structured substrate: A nematic liquid crystal in contact with a grating surface possessing an\nalternating stripe pattern of locally homeotropic and planar anchoring is\nstudied within the Frank--Oseen model. The combination of both chemical and\ngeometrical surface pattern leads to rich phase diagrams, involving a\nhomeotropic, a planar, and a tilted nematic texture. The effect of the groove\ndepth and the anchoring strengths on the location and the order of phase\ntransitions between different nematic textures is studied. A zenithally\nbistable nematic device is investigated by confining a nematic liquid crystal\nbetween the patterned grating surface and a flat substrate with strong\nhomeotropic anchoring."
    },
    {
        "anchor": "A molecular dynamics simulation of polymer crystallization from oriented\n  amorphous state: Molecular process of crystallization from an oriented amorphous state was\nreproduced by molecular dynamics simulation for a realistic polyethylene model.\nInitial oriented amorphous state was obtained by uniaxial drawing an isotropic\nglassy state at 100 K. By the temperature jump from 100 K to 330 K, there\noccurred the crystallization into the fiber structure, during the process of\nwhich we observed the developments of various order parameters. The real space\nimage and its Fourier transform revealed that a hexagonally ordered domain was\ninitially formed, and then highly ordered crystalline state with stacked\nlamellae developed after further adjustment of the relative heights of the\nchains along their axes.",
        "positive": "The designs and deformations of rigidly and flat-foldable quadrilateral\n  mesh origami: Rigidly and flat-foldable quadrilateral mesh origami is the class of\nquadrilateral mesh crease patterns with one fundamental property: the patterns\ncan be folded from flat to fully-folded flat by a continuous one-parameter\nfamily of piecewise affine deformations that do not stretch or bend the\nmesh-panels. In this work, we explicitly characterize the designs and\ndeformations of all possible rigidly and flat-foldable quadrilateral mesh\norigami. Our key idea is a rigidity theorem (Theorem 3.1) that characterizes\ncompatible crease patterns surrounding a single panel and enables us to march\nfrom panel to panel to compute the pattern and its corresponding deformations\nexplicitly. The marching procedure is computationally efficient. So we use it\nto formulate the inverse problem: to design a crease pattern to achieve a\ntargeted shape along the path of its rigidly and flat-foldable motion. The\ninitial results on the inverse problem are promising and suggest a broadly\nuseful engineering design strategy for shape-morphing with origami."
    },
    {
        "anchor": "Schematic Models for Active Nonlinear Microrheology: We analyze the nonlinear active microrheology of dense colloidal suspensions\nusing a schematic model of mode-coupling theory. The model describes the\nstrongly nonlinear behavior of the microscopic friction coefficient as a\nfunction of applied external force in terms of a delocalization transition. To\nprobe this regime, we have performed Brownian dynamics simulations of a system\nof quasi-hard spheres. We also analyze experimental data on hard-sphere-like\ncolloidal suspensions [Habdas et al., Europhys. Lett., 2004, 67, 477]. The\nbehavior at very large forces is addressed specifically.",
        "positive": "Two exchange-correlation functionals compared for first-principles\n  liquid water: The first-principles description of liquid water using ab initio molecular\ndynamics (AIMD) based on Density Functional theory (DFT) has recently been\nfound to require long equilibration times, giving too low diffusivities and a\nclear over-structuring of the liquid.\n  In the light of these findings we compare here the room-temperature\ndescription offered by two different exchange correlation functionals: BLYP,\nthe most popular for liquid water so far, and RPBE, a revision of the widely\nused PBE.\n  We find for RPBE a less structured liquid with radial distribution functions\ncloser to the experimental ones than the ones of BLYP.\n  The diffusivity obtained with RPBE for heavy water is still 20% lower than\nthe corresponding experimental value, but it represents a substantial\nimprovement on the BLYP value, one order of magnitude lower than experiment.\n  These characteristics and the hydrogen-bond (HB) network imperfection point\nto an effective temperature ~3% lower than the actual simulation temperature\nfor the RPBE liquid, as compared with BLYP's ~17% deviation.\n  The too long O--O average nearest-neighbor distance observed points to an\nexcessively weak HB, possibly compensating more fundamental errors in the DFT\ndescription."
    },
    {
        "anchor": "Systematic extension of the Cahn-Hilliard model for motility-induced\n  phase separation: We consider a continuum model for motility-induced phase separation (MIPS) of\nactive Brownian particles [J. Chem. Phys. 142, 224149 (2015)]. Using a recently\nintroduced perturbative analysis [Phys. Rev. E 98, 020604(R) (2018)], we show\nthat this continuum model reduces to the classic Cahn-Hilliard (CH) model near\nthe onset of MIPS. This makes MIPS another example of the so-called active\nphase separation. We further introduce a generalization of the perturbative\nanalysis to the next higher order. This results in a generic higher order\nextension of the CH model for active phase separation. Our analysis establishes\nthe mathematical link between the basic mean-field MIPS model on the one hand,\nand the leading order and extended CH models on the other hand. Comparing\nnumerical simulations of the three models, we find that the leading order CH\nmodel agrees nearly perfectly with the full continuum model near the onset of\nMIPS. We also give estimates of the control parameter beyond which the higher\norder corrections become relevant and compare the extended CH model to recent\nphenomenological models.",
        "positive": "Collaborative behavior of intruders moving amid grains: We investigate the motion of groups of intruders in a two-dimensional\ngranular system by using discrete numerical simulations. By imposing either a\nconstant velocity or a thrusting force on larger disks (intruders) that move\nwithin smaller ones (grains), we obtained instantaneous positions and\ncomponents of forces for each intruder and grain. We found that (i) intruders\ncooperate even when at relatively large distances from each other; (ii) the\ncooperative dynamics is the result of contact chains linking the intruders as\nwell as compaction and expansion of the granular medium in front and behind,\nrespectively, each intruder; (iii) the collaborative behavior depends on the\ninitial arrangement of intruders; and (iv) for some initial arrangements, the\nsame spatial configuration is eventually reached. Finally, we show the\nexistence of an optimal distance for minimum drag for a given set of intruders,\nwhich can prove useful for devices stirring the ground or other granular\nsurfaces."
    },
    {
        "anchor": "Effect of milk fat content on the viscoelasticity of mozzarella-type\n  cheese curds: The effect of fat content in cheese curds on their rheological properties was\nexamined using dynamic shear measurements. Surplus fat addition to milk samples\ncaused two distinct types of changes in the temperature dependence of the\nviscoelastic moduli of resultant curds. The first was a significant reduction\nin the moduli over a wide temperature range, which is attributed to the\npresence of liquefied fat globules within the milk protein network. The second\nwas the excess contribution to the low-temperature moduli owing to the\nreinforcing effect of solidified fat globules. An upward shift in the sol-gel\nphase transition temperature driven by an increased fat content was also\nobserved.",
        "positive": "Density-scaling exponents and virial potential-energy correlation\n  coefficients for the (2n,n) Lennard-Jones system: This paper investigates the relation between the density-scaling exponent\n$\\gamma$ and the virial potential-energy correlation coefficient $R$ at several\nthermodynamic state points in three dimensions for the generalized $(2n,n)$\nLennard-Jones (LJ) system for $n=4, 9, 12, 18$, as well as for the standard\n$n=6$ LJ system in two, three, and four dimensions. The state points studied\ninclude many low-density states at which the virial potential-energy\ncorrelations are not strong. For these state points we find the roughly linear\nrelation $\\gamma\\cong 3nR/d$ in $d$ dimensions. This result is discussed in\nlight of the approximate \"extended inverse power law\" description of\ngeneralized LJ potentials [N. P. Bailey et al., J. Chem. Phys. 129, 184508\n(2008)]. In the plot of $\\gamma$ versus $R$ there is in all cases a transition\naround $R\\approx 0.9$, above which $\\gamma$ starts to decrease as $R$\napproaches unity. This is consistent with the fact that $\\gamma\\rightarrow\n2n/d$ for $R\\rightarrow 1$, a limit that is approached at high densities and/or\ntemperatures at which the repulsive $r^{-2n}$ term dominates the physics."
    },
    {
        "anchor": "Experimental Interpretation of Interfacial Separation and Squeezing\n  Pressure: The logarithmic relation between interfacial separation and squeezing\npressure between randomly rough surfaces, has been predicted by both theory and\nexperiment. However, the experimental slope between interfacial separation and\nlogarithmic squeezing pressure, is slightly bigger than that predicted by\ntheory. Here we present a detailed explanation on the slope difference between\ntheory and experiment.",
        "positive": "Electrostatics of liquid interfaces: The standard Maxwell formulation of the problem of polarized dielectrics\nsuffers from a number of difficulties, both conceptual and practical. These\ndifficulties are particularly significant in the case of liquid interfaces,\nwhere the ability of the interfacial multipoles to change their orientations to\nminimize their free energies leads to interfacial polarization localized within\na thin microscopic layer. A formalism to capture this physical reality of\nlocalized interfacial polarization is proposed and is based on the surface\ncharge as the source of microscopic electric fields in dielectrics. The surface\ncharge density incorporates the local structure of the interface into\nelectrostatic calculations. The corresponding surface susceptibility and\ninterface dielectric constant provide local closures to the electrostatic\nboundary value problem. A robust approach to calculate the surface\nsusceptibility from numerical simulations is proposed. The susceptibility can\nalternatively be extracted from a number of solution experiments, in particular\nthose sensitive to the overall dipole moment of a closed dielectric surface.\nThe theory is applied to the solvent-induced spectral shift and high-frequency\ndielectric response of solutions."
    },
    {
        "anchor": "A maximum-entropy model to predict 3D structural ensembles of chromatins\n  from pairwise distances: Applications to Interphase Chromosomes and\n  Structural Variants: The principles that govern the organization of genomes, which are needed for\na deeper understanding of how chromosomes are packaged and function in\neukaryotic cells, could be deciphered if the three-dimensional (3D) structures\nare known. Recently, single-cell imaging experiments have determined the 3D\ncoordinates of a number of loci in a chromosome. Here, we introduce a\ncomputational method (Distance Matrix to Ensemble of Structures, DIMES), based\non the maximum entropy principle, with experimental pair-wise distances between\nloci as constraints, to generate a unique ensemble of 3D chromatin structures.\nUsing the ensemble of structures, we quantitatively account for the\ndistribution of pair-wise distances, three-body co-localization and\nhigher-order interactions. We demonstrate that the DIMES method can be applied\nto both small length-scale and chromosome-scale imaging data to quantify the\nextent of heterogeneity and fluctuations in the shapes on various length\nscales. We develop a perturbation method that is used in conjunction with DIMES\nto predict the changes in 3D structures from structural variations. Our method\nalso reveals quantitative differences between the 3D structures inferred from\nHi-C and the ones measured in imaging experiments. Finally, the physical\ninterpretation of the parameters extracted from DIMES provides insights into\nthe origin of phase separation between euchromatin and heterochromatin domains.",
        "positive": "Likely equilibria of stochastic hyperelastic spherical shells and tubes: In large deformations, internally pressurised elastic spherical shells and\ntubes may undergo a limit-point, or inflation, instability manifested by a\nrapid transition in which their radii suddenly increase. The possible existence\nof such an instability depends on the material constitutive model. Here, we\nrevisit this problem in the context of stochastic incompressible hyperelastic\nmaterials, and ask the question: what is the probability distribution of stable\nradially symmetric inflation, such that the internal pressure always increases\nas the radial stretch increases? For the classic elastic problem, involving\nisotropic incompressible materials, there is a critical parameter value that\nstrictly separates the cases where inflation instability can occur or not. By\ncontrast, for the stochastic problem, we show that the inherent variability of\nthe probabilistic parameters implies that there is always competition between\nthe two cases. To illustrate this, we draw on published experimental data for\nrubber, and derive the probability distribution of the corresponding random\nshear modulus to predict the inflation responses for a spherical shell and a\ncylindrical tube made of a material characterised by this parameter."
    },
    {
        "anchor": "Optical forces and torques in non-uniform beams of light: The spin angular momentum in an elliptically polarized beam of light plays\nseveral noteworthy roles in optical traps. It contributes to the linear\nmomentum density in a non-uniform beam, and thus to the radiation pressure\nexerted on illuminated objects. It can be converted into orbital angular\nmomentum, and thus can exert torques even on optically isotropic objects. Its\ncurl, moreover, contributes to both forces and torques without spin-to-orbit\nconversion. We demonstrate these effects experimentally by tracking colloidal\nspheres diffusing in elliptically polarized optical tweezers. Clusters of\nspheres circulate deterministically about the beam's axis. A single sphere, by\ncontrast, undergoes stochastic Brownian vortex circulation that maps out the\noptical force field.",
        "positive": "The Electrostatic Screening Length in Concentrated Electrolytes\n  Increases with Concentration: According to classical electrolyte theories interactions in dilute (low ion\ndensity) electrolytes decay exponentially with distance, with the Debye\nscreening length the characteristic length-scale. This decay length decreases\nmonotonically with increasing ion concentration, due to effective screening of\ncharges over short distances. Thus within the Debye model no long-range forces\nare expected in concentrated electrolytes. Here we reveal, using experimental\ndetection of the interaction between two planar charged surfaces across a wide\nrange of electrolytes, that beyond the dilute (Debye-Huuckel) regime the\nscreening length increases with increasing concentration. The screening lengths\nfor all electrolytes studied - including aqueous NaCl solutions, ionic liquids\ndiluted with propylene carbonate, and pure ionic liquids - collapse onto a\nsingle curve when scaled by the dielectric constant. This non-monotonic\nvariation of the screening length with concentration, and its generality across\nionic liquids and aqueous salt solutions, demonstrates an important\ncharacteristic of concentrated electrolytes of substantial relevance from\nbiology to energy storage."
    },
    {
        "anchor": "Pressure dependent friction on granular slopes close to avalanche: We investigate the sliding of objects on an inclined granular surface close\nto the avalanche threshold. Our experiments show that the stability is driven\nby the surface deformations. Heavy objects generate footprint-like deformations\nwhich stabilize the objects on the slopes. Light objects do not disturb the\nsandy surfaces and are also stable. For intermediate weights, the deformations\nof the surface destabilize the objects and generate sliding. A characteristic\npressure for which the solid friction is minimal is evidenced. Applications to\nthe locomotion of devices and animals on sandy slopes as a function of their\nmass are proposed.",
        "positive": "Reply to \"Comment on `Jamming at zero temperature and zero applied\n  stress: The epitome of disorder' \": We answer the questions raised by Donev, Torquato, Stillinger, and Connelly\nin their \"Comment on \"Jamming at zero temperature and zero applied stress: The\nepitome of disorder.' \" We emphasize that we follow a fundamentally different\napproach than they have done to reinterpret random close packing in terms of\nthe \"maximally random jammed\" framework. We define the \"maximally random jammed\npacking fraction\" to be where the largest number of initial states, chosen\ncompletely randomly, have relaxed final states at the jamming threshold in the\nthermodynamic limit. Thus, we focus on an ensemble of states at the jamming\nthreshold, while DTSC are interested in determining the amount of order and\ndegree of jamming for a particular configuration. We also argue that\nsoft-particle systems are as \"clean\" as those using hard spheres for studying\njammed packings and point out the benefits of using soft potentials."
    },
    {
        "anchor": "Structural signatures of ultrastability in a deposited glassformer: Glasses obtained from vapor deposition on a cold substrate have superior\nthermodynamic and kinetic stability with respect to ordinary glasses. Here we\nperform molecular dynamics simulations of vapor deposition of a model\nglass-former and investigate the origin of its high stability compared to that\nof ordinary glasses. We find that the vapor deposited glass is characterized by\nlocally favoured structures (LFS) whose occurrence correlates with its\nstability, reaching a maximum at the optimal deposition temperature. The\nformation of LFS is enhanced near the free surface, hence supporting the idea\nthat the stability of vapor deposited glasses is connected to the relaxation\ndynamics at the surface.",
        "positive": "Turbulence-induced clustering in compressible active fluids: We study a novel phase of active polar fluids, which is characterized by the\ncontinuous creation and destruction of dense clusters due to self-sustained\nturbulence. This state arises due to the interplay of the self-advection of the\naligned swimmers and their defect topology. The typical cluster size is\ndetermined by the characteristic vortex size. Our results are obtained by\ninvestigating a continuum model of compressible polar active fluids, which\nincorporates typical experimental observations in bacterial suspensions by\nassuming a non-monotone dependence of speed on density."
    },
    {
        "anchor": "Flexoelectricity and competition of time scales in electroconvection: Novel behavior in electroconvection (EC) has been detected in nematic liquid\ncrystals (NLCs) under the condition of comparable timescales of the director\nrelaxation and the period of the driving ac voltage. The studied NLCs exhibit\nstandard EC (s-EC) at the onset of the instability, except one compound in\nwhich nonstandard EC (ns-EC) has been detected. In the relevant frequency\nregion, the threshold voltage for conductive s-EC bends down considerably,\nwhile for dielectric s-EC it bends up strongly with the decrease of the driving\nfrequency. We show that inclusion of the flexoelectric effect into the\ntheoretical description of conductive s-EC leads to quantitative agreement,\nwhile for dielectric s-EC a qualitative agreement is achieved. The frequency\ndependence of the threshold voltage for ns-EC strongly resembles that of the\ndielectric s-EC.",
        "positive": "Revealing the co-action of viscous and multistability hysteresis in an\n  adhesive, nominally flat punch: A combined numerical and experimental study: Viscoelasticity is well known to cause significant hysteresis of crack\nclosure and opening when an elastomer is brought in and out of contact with a\nflat, rigid, adhesive counterface. A separate origin of adhesive hysteresis is\nsmall-scale, elastic multistability. Here, we study a system in which both\nmechanisms act concurrently. Specifically, we compare the simulated and\nexperimentally measured time evolution of the interfacial force and the real\ncontact area between a soft elastomer and a rigid, flat punch, to which\nsmall-scale, single-sinusoidal roughness is added. To this end, we further the\nGreen's function molecular dynamics method and extend recently developed\nimaging techniques to elucidate the rate- and preload-dependence of the\npull-off process. Our results reveal that hysteresis is much enhanced when the\nsaddle points of the topography come into contact, which, however, is impeded\nby viscoelastic forces and may require sufficiently large preloads. A similar\ncoaction of viscous- and multistability effects is expected to occur in\nmacroscopic polymer contacts and to be relevant, e.g., for pressure-sensitive\nadhesives and modern adhesive gripping devices."
    },
    {
        "anchor": "Soft and stiff normal modes in floppy colloidal square lattices: Floppy microscale spring networks are widely studied in theory and\nsimulations, but no well-controlled experimental system currently exists. Here,\nwe show that square lattices consisting of colloid-supported lipid bilayers\nfunctionalized with DNA linkers act as microscale floppy spring networks. We\nextract their normal modes by inverting the particle displacement correlation\nmatrix, showing the emergence of a spectrum of soft modes with low effective\nstiffness in addition to stiff modes that derive from linker interactions.\nEvaluation of the softest mode, a uniform shear mode, reveals that shear\nstiffness decreases with lattice size. Experiments match well with Brownian\nparticle simulations and we develop a theoretical description based on mapping\ninteractions onto linear response to describe the modes. Our results reveal the\nimportance of entropic steric effects, and can be used for developing\nreconfigurable materials at the colloidal length scale.",
        "positive": "Intercellular Friction and Motility Drive Orientational Order in Cell\n  Monolayers: Spatiotemporal patterns in multicellular systems are important to\nunderstanding tissue dynamics, for instance, during embryonic development and\ndisease. Here, we use a multiphase field model to study numerically the\nbehavior of a near-confluent monolayer of deformable cells with intercellular\nfriction. Varying friction and cell motility drives a solid-liquid transition,\nand near the transition boundary, we find the emergence of nematic order of\ncell deformation driven by shear-aligning cellular flows. Intercellular\nfriction endows the monolayer with a finite viscosity, which significantly\nincreases the spatial correlation in the flow and, concomitantly, the extent of\nnematic order. We also show that hexatic and nematic order are tightly coupled\nand propose a mechanical-geometric model for the colocalization of +1/2 nematic\ndefects and 5-7 disclination pairs, which are the structural defects in the\nhexatic phase. Such topological defects coincide with regions of high cell-cell\noverlap, suggesting that they may mediate cellular extrusion from the\nmonolayer, as found experimentally. Our results delineate a mechanical basis\nfor the recent observation of nematic and hexatic order in multicellular\ncollectives in experiments and simulations and pinpoint a generic pathway to\ncouple topological and physical effects in these systems."
    },
    {
        "anchor": "Collective behavior of Vicsek particles without and with obstacles: In our work we have studied a two-dimensional suspension of finite-size\nVicsek hard-disks, whose time evolution follows an event-driven dynamics\nbetween subsequent time steps. Having compared its collective behaviour with\nthe one expected for a system of scalar Vicsek point-like particles, we have\nanalysed the effect of considering two possible bouncing rules between the\ndisks: a Vicsek-like rule and a pseudo-elastic one, focusing on the\norder-disorder transition. Next, we have added to the two-dimensional\nsuspension of hard-disk Vicsek particles disk-like passive obstacles of two\ntypes: either fixed in space or moving according to the same event-driven\ndynamics. We have performed a detailed analysis of the particles' collective\nbehaviour observed for both fixed and moving obstacles. In the fixed obstacles\ncase, we have observed formation of clusters at low noise, in agreement with\nprevious studies. When using moving passive obstacles, we found that that order\nof active particles is better destroyed as the drag of obstacles increases. In\nthe no drag limit an interesting result was found: introduction of low drag\npassive particles can lead in some cases to a more ordered state of active\nflocking particles than what they show in bulk.",
        "positive": "Evidence for Unusual Dynamical Arrest Scenario in Short Ranged Colloidal\n  Systems: Extensive molecular dynamics simulation studies of particles interacting via\na short ranged attractive square-well (SW) potential are reported. The\ncalculated loci of constant diffusion coefficient $D$ in the\ntemperature-packing fraction plane show a re-entrant behavior, i.e. an increase\nof diffusivity on cooling, confirming an important part of the high\nvolume-fraction dynamical-arrest scenario earlier predicted by theory for\nparticles with short ranged potentials. The more efficient localization\nmechanism induced by the short range bonding provides, on average, additional\nfree volume as compared to the hard-sphere case and results in faster dynamics."
    },
    {
        "anchor": "Coarse-grained curvature tensor on polygonal surfaces: Using concepts from integral geometry, we propose a definition for a local\ncoarse-grained curvature tensor that is well-defined on polygonal surfaces.\nThis coarse-grained curvature tensor shows fast convergence to the curvature\ntensor of smooth surfaces, capturing with accuracy not only the principal\ncurvatures but also the principal directions of curvature. Thanks to the\nadditivity of the integrated curvature tensor, coarse-graining procedures can\nbe implemented to compute it over arbitrary patches of polygons. When computed\nfor a closed surface, the integrated curvature tensor is identical to a rank-2\nMinkowski tensor. We also provide an algorithm to extend an existing C++\npackage, that can be used to compute efficiently local curvature tensors on\ntriangulated surfaces.",
        "positive": "A Lattice Boltzmann Model of Ternary Fluid Mixtures: A lattice Boltzmann model is introduced which simulates oil-water-surfactant\nmixtures. The model is based on a Ginzburg-Landau free energy with two scalar\norder parameters. Diffusive and hydrodynamic transport is included. Results are\npresented showing how the surfactant diffuses to the oil-water interfaces thus\nlowering the surface tension and leading to spontaneous emulsification. The\nrate of emulsification depends on the viscosity of the ternary fluid."
    },
    {
        "anchor": "Relaxation of a Colloidal Particle into a Nonequilibrium Steady State: We study the relaxation of a single colloidal sphere which is periodically\ndriven between two nonequilibrium steady states. Experimentally, this is\nachieved by driving the particle along a toroidal trap imposed by scanned\noptical tweezers. We find that the relaxation time after which the probability\ndistributions have been relaxed is identical to that obtained by a steady state\nmeasurement. In quantitative agreement with theoretical calculations the\nrelaxation time strongly increases when driving the system further away from\nthermal equilibrium.",
        "positive": "Enhanced motility of a microswimmer in rigid and elastic confinement: We analyse the effect of confining rigid and elastic boundaries on the\nmotility of a model dipolar microswimmer. Flexible boundaries are deformed by\nthe velocity field of the swimmer in such a way that the motility of both\nextensile and contractile swimmers is enhanced. The magnitude of the increase\nin swimming velocity is controlled by the ratio of the swimmer-advection and\nelastic timescales, and the dipole moment of the swimmer. We explain our\nresults by considering swimming between inclined rigid boundaries."
    },
    {
        "anchor": "An Aspect of Granulence in view of Multifractal Analysis: The probability density function of velocity fluctuations of {\\em glanulence}\nobserved by Radjai and Roux in their two-dimensional simulation of a slow\ngranular flow under homogeneous quasistatic shearing is studied by the\nmultifractal analysis for fluid turbulence proposed by the present authors.It\nis shown that the system of granulence and of turbulence have indeed common\nscaling characteristics.",
        "positive": "Highly sticky surfaces made by electrospun polymer nanofibers: We report on a comprehensive study of the unique adhesive properties of mats\nof polymethylmethacrylate (PMMA) nanofibers produced by electrospinning. Fibers\nare deposited on glass, varying the diameter and the relative orientation of\nthe polymer filaments (random vs aligned configuration). While no significant\nvariation is observed in the static contact angle (about 130{\\deg}) of\ndeposited water drops upon changing the average fiber diameter up to the\nmicrometer scale, fibers are found to exhibit unequalled water adhesion. Placed\nvertically, they can hold up water drops as large as 60 microL, more than twice\nthe values typically obtained with hairy surfaces prepared by different\nmethods. For aligned fibers with anisotropic wetting behavior, the maximum\nvolume measured in the direction perpendicular to the fibers goes up to 90\n{\\mu}L. This work suggests new routes to tailor the wetting behavior on\nextended areas by nanofiber coatings, with possible applications in adsorbing\nand catalytic surfaces, microfluidic devices, and filtration technologies."
    },
    {
        "anchor": "Pore-size dependence and characteristics of water diffusion in slit-like\n  micropores: The temperature dependence of the dynamics of water inside microporous\nactivated carbon fibers (ACF) is investigated by means of incoherent elastic\nand quasi- elastic neutron scattering techniques. The aim is to evaluate the\neffect of increasing pore size on the water dynamics in these primarily\nhydrophobic slit-shaped channels. Using two different micropore sizes (\\sim 12\nand 18 {\\AA}, denoted respectively ACF-10 and ACF-20), a clear suppression of\nthe mobility of the water molecules is observed as the pore gap or temperature\ndecreases. This suppression is accompanied by a systematic dependence of the\naverage translational diffusion coefficient Dr and relaxation time <{\\tau}_0>\nof the restricted water on pore size and temperature. The observed Dr values\nare tested against a proposed scaling law, in which the translational diffusion\ncoefficient Dr of water within a nanoporous matrix was found to depend solely\non two single parameters, a temperature independent translational diffusion\ncoefficient Dc associated with the water bound to the pore walls and the ratio\n{\\theta} of this strictly confined water to the total water inside the pore,\nyielding unique characteristic parameters for water transport in these carbon\nchannels across the investigated temperature range.",
        "positive": "Mean-field model for a mixture of biaxial nematogens and dipolar\n  nanoparticles: We analyze a mean-field model for mixtures involving biaxial nematogens and\ndipolar nanoparticles, taking into account orientational and isotropic pair\ninteractions between nematogens, but also orientational nematogen-nanoparticle\ninteractions. We determine bulk equilibrium phase diagrams for a wide range of\ninteraction strengths, identifying in each case the effect of the nanoparticles\non the stability of nematic phases and on the appearance of multicritical\npoints. Special attention is given to the limit of low concentration of\nnanoparticles, in which their effect on the temperatures of both the\nfirst-order uniaxial-isotropic and the continuous biaxial-uniaxial transitions\nis investigated in detail."
    },
    {
        "anchor": "Motor driven microtubule shape fluctuations - force from within the\n  lattice: We develop a general theory of microtubule (MT) deformations by molecular\nmotors generating internal force doublets within the MT lattice. We describe\ntwo basic internal excitations, the S and V shape, and compare them with\nexperimental observations from literature. We explain the special role of\ntubulin vacancies and the dramatic deformation amplifying effect observed for\nkatanin acting at positions of defects. Experimentally observed shapes are used\nto determine the ratio of MT shear and stretch moduli ($\\approx\n6\\times10^{-5}$) and to estimate the forces induced in the MT lattice by\nkatanin (10's of pN). For many motors acting on a single MT we derive\nexpressions for the end-to-end distance reduction and provide criteria for\ndominance of this new effect over thermal fluctuations. We conclude that\nmolecular motors if acting cooperatively can ''animate'' MTs from within the\nlattice and induce slack even without cross-bridging to other structures, a\nscenario very much reminiscent of the motor driven axoneme.",
        "positive": "Geometry of wave propagation on active deformable surfaces: Fundamental biological and biomimetic processes, from tissue morphogenesis to\nsoft robotics, rely on the propagation of chemical and mechanical surface waves\nto signal and coordinate active force generation. The complex interplay between\nsurface geometry and contraction wave dynamics remains poorly understood, but\nwill be essential for the future design of chemically-driven soft robots and\nactive materials. Here, we couple prototypical chemical wave and\nreaction-diffusion models to non-Euclidean shell mechanics to identify and\ncharacterize generic features of chemo-mechanical wave propagation on active\ndeformable surfaces. Our theoretical framework is validated against recent data\nfrom contractile wave measurements on ascidian and starfish oocytes, producing\ngood quantitative agreement in both cases. The theory is then applied to\nillustrate how geometry and preexisting discrete symmetries can be utilized to\nfocus active elastic surface waves. We highlight the practical potential of\nchemo-mechanical coupling by demonstrating spontaneous wave-induced locomotion\nof elastic shells of various geometries. Altogether, our results show how\ngeometry, elasticity and chemical signaling can be harnessed to construct\ndynamically adaptable, autonomously moving mechanical surface wave guides."
    },
    {
        "anchor": "Long-Range Nematic Order in Two-Dimensional Active Matter: Working in two space dimensions, we show that the orientational order\nemerging from self-propelled polar particles aligning nematically is\nquasi-long-ranged beyond $\\ell_{\\rm r}$, the scale associated to induced\nvelocity reversals, which is typically extremely large and often cannot even be\nmeasured. Below $\\ell_{\\rm r}$, nematic order is long-range. We construct and\nstudy a hydrodynamic theory for this de facto phase and show that its structure\nand symmetries differ from conventional descriptions of active nematics. We\ncheck numerically our theoretical predictions, in particular the presence of\n$\\pi$-symmetric propagative sound modes, and provide estimates of all scaling\nexponents governing long-range space-time correlations.",
        "positive": "Wrinkles, folds and plasticity in granular rafts: We investigate the mechanical response of a compressed monolayer of large and\ndense particles at a liquid-fluid interface: a granular raft. Upon compression,\nrafts first wrinkle; then, as the confinement increases, the deformation\nlocalizes in a unique fold. This characteristic buckling pattern is usually\nassociated to floating elastic sheets and as a result, particle laden\ninterfaces are often modeled as such. Here, we push this analogy to its limits\nby comparing the first quantitative measurements of the raft morphology to a\ntheoretical continuous elastic model of the interface. We show that although\npowerful to describe the wrinkle wavelength, the wrinkle-to-fold transition and\nthe fold shape, this elastic description does not capture the finer details of\nthe experiment. We describe an unpredicted secondary wavelength, a compression\ndiscrepancy with the model and a hysteretic behavior during compression cycles,\nall of which are a signature of the intrinsic discrete and frictional nature of\ngranular rafts. It suggests also that these composite materials exhibit both\nplastic transition and jamming dynamics."
    },
    {
        "anchor": "2D nanoporous membrane for cation removal from water: effects of ionic\n  valence, membrane hydrophobicity and pore size: Using molecular dynamic simulations we show that single-layers of molybdenum\ndisulfide (MoS$_2$) and graphene can effectively reject ions and allow high\nwater permeability. Solutions of water and three cations with different valence\n(Na$^+$, Zn$^{2+}$ and Fe$^{3+}$) were investigated in the presence of the two\ntypes of membranes and the results indicate a high dependence of the ion\nrejection on the cation charge. The associative characteristic of ferric\nchloride leads to a high rate of ion rejection by both nanopores, while the\nmonovalent sodium chloride induces lower rejection rates. Particularly, MoS$_2$\nshows 100\\% of Fe$^{3+}$ rejection for all pore sizes and applied pressures. On\nthe other hand, the water permeation did not varies with the cation valence,\nhaving dependence only with the nanopore geometric and chemical characteristic.\nThis study helps to understand the fluid transport through nanoporous membrane,\nessential for the development of new technologies for pollutants removal from\nwater.",
        "positive": "Correlation between surface topography and slippage: a Molecular\n  Dynamics study: Using Molecular Dynamics simulations of a polymer liquid flowing past flat\nand patterned surfaces, we investigate the influence of corrugation,\nwettability and pressure on slippage and friction at the solid-liquid\ninterface. For one-dimensional, rectangular grooves, we observe a gradual\ncrossover between the Wenzel state, where the liquid fills the grooves, and the\nCassie state, where the corrugation supports the liquid and the grooves are\nfilled with vapor. Using two independent flow set-ups, we characterize the\nnear-surface flow by the slip length, $\\delta$, and the position,\n$z_\\textrm{h}$, at which viscous and frictional stresses are balanced according\nto Navier's partial slip boundary condition. This hydrodynamic boundary\nposition depends on the pressure inside the channel and may be located above\nthe corrugated surface. In the Cassie state, we observe that the edges of the\ncorrugation contribute to the friction."
    },
    {
        "anchor": "Microphase separation in linear multiblock copolymers under poor solvent\n  conditions: Molecular dynamics simulations are used to study the phase behavior of linear\nmultiblock copolymers with two types of monomers, A and B, where the length of\nthe polymer blocks $N_{A}$ and $N_{B}$ ($N_{A}=N_{B}=N$), the number of the\nblocks $n_{A}$ and $n_{B}$ ($n_{A}=n_{B}=n$), and the solvent quality varies.\nThe fraction $f$ of A-type monomers is kept constant and equal to 0.5. Whereas\nat high enough temperatures these macromolecules form coil structures, where\neach block A or B forms rather individual clusters, at low enough temperatures\nA and B monomers from different blocks can join together forming clusters of A\nor B monomers. The dependence of the formation of these clusters on the varied\nparameters is discussed in detail, providing a full understanding of the phase\nbehavior of linear multiblock copolymers, at least for this symmetrical case.",
        "positive": "Brownian Thermometry Beyond Equilibrium: Since Albert Einstein's seminal 1905-paper on Brownian motion, the\ntemperature of fluids and gases of known viscosity can be deduced from\nobservations of the fluctuations of small suspended probe particles. We\nsummarize recent generalizations of this standard technique of Brownian\nthermometry to situations involving spatially heterogeneous temperature fields\nand other non-equilibrium conditions in the solvent medium. The notion of\neffective temperatures is reviewed and its scope critically assessed. Our\nemphasis is on practically relevant real-world applications, for which\neffective temperatures have been explicitly computed and experimentally\nconfirmed. We also elucidate the relation to the more general concept of\n(effective) temperature spectra and their measurement by Brownian\nthermospectrometry. Finally, we highlight the conceptual importance of\nnon-equilibrium thermometry for active and biological matter, such as\nmicroswimmer suspensions or biological cells, which often play the role of\nnon-thermal ('active') heat baths for embedded Brownian degrees of freedom."
    },
    {
        "anchor": "Magnetically responsive gourd-shaped colloidal particles in cholesteric\n  liquid crystals: Particle shape and medium chirality are two key features recently used to\ncontrol anisotropic colloidal self-assembly and dynamics in liquid crystals.\nHere, we study magnetically responsive gourd-shaped colloidal particles\ndispersed in cholesteric liquid crystals with periodicity comparable or smaller\nthan the particle's dimensions. Using magnetic manipulation and optical\ntweezers, which allow one to position colloids near the confining walls, we\nmeasured the elastic repulsive interactions of these particles with confining\nsurfaces and found that separation-dependent particle-wall interaction force is\na non-monotonic function of separation and shows oscillatory behavior. We show\nthat gourd-shaped particles in cholesterics reside not on a single\nsedimentation level, but on multiple long-lived metastable levels separated by\na distance comparable to cholesteric periodicity. Finally, we demonstrate\nthree-dimensional laser tweezers assisted assembly of gourd-shaped particles\ntaking advantage of both orientational order and twist periodicity of\ncholesterics, potentially allowing new forms of orientationally and\npositionally ordered colloidal organization in these media.",
        "positive": "Effective free energy for pinned membranes: We consider membranes adhered through specific receptor-ligand bonds. Thermal\nundulations of the membrane induce effective interactions between adhesion\nsites. We derive an upper bound to the free energy that is independent of\ninteraction details. To lowest order in a systematic expansion we obtain\ntwo-body interactions which allow to map the free energy onto a lattice gas\nwith constant density. The induced interactions alone are not strong enough to\nlead to a condensation of individual adhesion sites. A measure of the thermal\nroughness is shown to depend on the inverse square root of the density of\nadhesion sites, which is in good agreement with previous computer simulations."
    },
    {
        "anchor": "Ground State Energy of the Low Density Bose Gas: Now that the properties of low temperature Bose gases at low density, $\\rho$,\ncan be examined experimentally it is appropriate to revisit some of the\nformulas deduced by many authors 4-5 decades ago. One of these is that the\nleading term in the energy/particle is $2\\pi \\hbar^2 \\rho a/m$, where $a$ is\nthe scattering length. Owing to the delicate and peculiar nature of bosonic\ncorrelations, four decades of research have failed to establish this plausible\nformula rigorously. The only known lower bound for the energy was found by\nDyson in 1957, but it was 14 times too small. The correct bound is proved here.",
        "positive": "Onsager's variational principle for nonreciprocal systems with odd\n  elasticity: Using Onsager's variational principle, we derive dynamical equations for a\nnonequilibrium active system with odd elasticity. The elimination of the extra\nvariable that is coupled to the nonequilibrium driving force leads to the\nnonreciprocal set of equations for the material coordinates. The obtained\nnonreciprocal equations manifest the physical origin of the odd elastic\nconstants that are proportional to the nonequilibrium force and the friction\ncoefficients. Our approach offers a systematic and consistent way to derive\nnonreciprocal equations for active matter in which the time-reversal symmetry\nis broken."
    },
    {
        "anchor": "Optimized Constant Pressure Stochastic Dynamics: A recently proposed method for computer simulations in the\nisothermal-isobaric (NPT) ensemble, based on Langevin-type equations of motion\nfor the particle coordinates and the ``piston'' degree of freedom, is\nre-derived by straightforward application of the standard Kramers-Moyal\nformalism. An integration scheme is developed which reduces to a\ntime-reversible symplectic integrator in the limit of vanishing friction. This\nalgorithm is hence expected to be quite stable for small friction, allowing for\na large time step. We discuss the optimal choice of parameters, and present\nsome numerical test results.",
        "positive": "Dilatancy of frictional granular materials under oscillatory shear with\n  constant pressure: We perform numerical simulations of a two-dimensional frictional granular\nsystem under oscillatory shear confined by constant pressure. We found that the\nsystem undergoes dilatancy as the strain increases. We confirmed that\ncompaction also takes place at an intermediate strain amplitude for a small\nmutual friction coefficient between particles. We also found that compaction\ndepends on the confinement pressure while dilatancy little depends on the\npressure."
    },
    {
        "anchor": "Propulsion, deformation, and confinement response of hollow\n  nanocellulose millimotors: Micromotor and nanomotor particles are typically made using dense solid\nparticles that can sediment or be trapped in confined flow environments.\nCreation of much larger motors should be possible if a very low-density system\nis used with sufficient strength to carry liquid and still experience\npropulsive motion. Light, dense millimotors should also be able to deform more\nthan dense solid ones in constrictions. Millimotors are created from permeable\ncapsules of bacterial cellulose that are coated with catalase-containing\nmetal-organic frameworks, enabling reactive propulsion in aqueous hydrogen\nperoxide. The motion of the motors is quantified using particle tracking and\nthe deformation is measured using microcapillary compression and flow through\nconfined channels. Two different propulsion mechanisms are dominant depending\non the motor surface chemistry: oxygen bubbles are expelled from hydrophilic\nmillimotors, driving motion via reaction force and buoyancy. Hydrophobic\nmillimotors remain attached to growing bubbles and move by buoyancy alone.\nDespite their large size, the low-density capsules compress to pass through\ncontractions that would impede and be blocked by solid motors. The sparse\nstructure but relatively large size of the motors enables them to transport\nsignificant volumes of liquid using minimal solid mass as a motor support\nstructure.",
        "positive": "Pattern formation in wet granular matter under vertical vibrations: Experiments on a thin layer of cohesive wet granular matter under vertical\nvibrations reveal kink separated domains that collide with the container at\ndifferent phases. Due to the strong cohesion arising from the formation of\nliquid bridges between adjacent particles, the domains move collectively upon\nvibrations. Depending on the periodicity of this collective motion, the kink\nfronts may propagate, couple with each other and form rotating spiral patterns\nin the case of period tripling, or stay as standing wave patterns in the case\nof period doubling. Moreover, both patterns may coexist with granular `gas\nbubbles' - phase separation into a liquidlike and a gaslike state. Stability\ndiagrams for the instabilities measured with various granular layer mass $m$\nand container height $H$ are presented. The onsets for both types of patterns\nand their dependency on $m$ and $H$ can be quantitatively captured with a model\nconsidering the granular layer as a single particle colliding completely\ninelastically with the container."
    },
    {
        "anchor": "Pair-distribution function of active Brownian spheres in two spatial\n  dimensions: simulation results and analytic representation: We investigate the full pair-distribution function of a homogeneous\nsuspension of spherical active Brownian particles interacting by a\nWeeks-Chandler-Andersen potential in two spatial dimensions. The full\npair-distribution function depends on three coordinates describing the relative\npositions and orientations of two particles, the P\\'eclet number specifying the\nactivity of the particles, and their mean packing density. This\nfive-dimensional function is obtained from Brownian dynamics simulations. We\ndiscuss its structure taking into account all of its degrees of freedom. In\naddition, we present an approximate analytic expression for the product of the\nfull pair-distribution function and the interparticle force. We find that the\nanalytic expression, which is typically needed when deriving analytic models\nfor the collective dynamics of active Brownian particles, is in good agreement\nwith the simulation results. The results of this work can thus be expected to\nbe helpful for the further theoretical investigation of active Brownian\nparticles as well as nonequilibrium statistical physics in general.",
        "positive": "Glasses of dynamically asymmetric binary colloidal mixtures: Quiescent\n  properties and dynamics under shear: We investigate mixing effects on the glass state of binary colloidal\nhard-sphere-like mixtures with large size asymmetry, at a constant volume\nfraction phi = 0.61. The structure, dynamics and viscoelastic response as a\nfunction of mixing ratio reflect a transition between caging by one or the\nother component. The strongest effect of mixing is observed in systems\ndominated by caging of the large component. The possibility to pack a large\nnumber of small spheres in the free volume left by the large ones induces a\npronounced deformation of the cage of the large spheres, which become\nincreasingly delocalised. This results in faster dynamics and a strong\nreduction of the elastic modulus. When the relative volume fraction of small\nspheres exceeds that of large spheres, the small particles start to form their\nown cages, slowing down the dynamics and increasing the elastic modulus of the\nsystem. The large spheres become the minority and act as an impurity in the\nordering beyond the first neighbour shell, i.e. the cage, and do not directly\naffect the particle organisation on the cage level. In such a system, when\nshear at constant rate is applied, melting of the glass is observed due to\nfacilitated out-of-cage diffusion which is associated with structural\nanisotropy induced by shear."
    },
    {
        "anchor": "Effective simulations of interacting active droplets: Droplets form a cornerstone of the spatiotemporal organization of\nbiomolecules in cells. These droplets are controlled using physical processes\nlike chemical reactions and imposed gradients, which are costly to simulate\nusing traditional approaches, like solving the Cahn-Hilliard equation. To\novercome this challenge, we here present an alternative, efficient method. The\nmain idea is to focus on the relevant degrees of freedom, like droplet\npositions and sizes. We derive dynamical equations for these quantities using\nanalytical solutions to simplified situations. We verify our method against\nfully-resolved simulations and show that it can describe interacting droplets\nunder the influence of chemical reactions and external gradients using only a\nfraction of the computational costs of traditional methods. Our method can be\nextended to include other processes in the future and will thus serve as a\nrelevant platform for understanding the dynamics of droplets in cells.",
        "positive": "Johari-Goldstein Relaxation Events Are Metabasin Transitions: We show that by representing quasi-elastic and inelastic neutron scattering\nfrom propylene carbonate (PC) with an explicitly heterogeneous model, we\nrecover two distinct dynamic signatures in addition to diffusive motion. The\nintermediate scattering function provides access to the time-dependence of\nthese two dynamic processes, and they appear to correspond to transitions\nbetween inherent states and between metabasins on a potential energy landscape.\nBy fitting the full q-dependence of inelastic scattering, we confirm that that\nthe Johari-Goldstein ($\\beta_{JG}$) relaxation in PC is indistinguishable from\nmetabasin transitions."
    },
    {
        "anchor": "Brownian Vortexes: A particle diffusing around a point of stable mechanical equilibrium in a\nstatic but non-conservative force field enters into a steady state\ncharacterized by circulation in the probability flux. Circulation in such a\nBrownian vortex is not simply a deterministic response to the solenoidal\ncomponent of the force, but rather reflects an interplay between force-driven\nprobability currents and diffusion. As an example of this previously\nunrecognized class of stochastic heat engines, we consider a colloidal sphere\nstably trapped in a conventional optical tweezer. Rather than coming into\nthermodynamic equilibrium with the surrounding heat bath, the particle's\nBrownian fluctuations are biased into a toroidal roll. We demonstrate both\ntheoretically and experimentally that the circulation in this practical\nrealization of the Brownian vortex can undergo flux reversal.",
        "positive": "Controlling crystal self-assembly using a real-time feedback scheme: We simulate crystallisation of hard spheres with short-ranged attractive\npotentials, as a model self-assembling system. We show how measurements of\ncorrelation and response functions during assembly can be used to tune the\ninteraction parameters as assembly proceeds, in order to obtain high-quality\ncrystals. The method we use is independent of details of the interaction\npotential and of the structure of the final crystal - we propose that it could\nbe applied to a wide range of self-assembling systems."
    },
    {
        "anchor": "Bidisperse micro fluidized beds: Effect of bed inclination on mixing: Micro fluidized beds are basically suspensions of solid particles by an\nascending fluid in a mm-scale tube, with applications in chemical and\npharmaceutical processes involving powders. Although in many applications beds\nare polydisperse, previous works considered only monodisperse beds aligned in\nthe vertical direction. However, introducing an inclination with respect to\ngravity leads to different bed patterns and mixing levels, which can be\nbeneficial for some applications. In this paper, we investigate experimentally\nthe behavior of micro gas-solid beds consisting of bidisperse mixtures under\ndifferent inclinations. In our experiments, mono and bidisperse beds are filmed\nwith a high-speed camera and the images are processed for obtaining\nmeasurements at both the bed and grain scales. We show that the degree of\nsegregation is larger for vertical beds, but mixing varies non-monotonically\nwith inclination, with an optimal angle of 30$^{\\circ}$--50$^{\\circ}$ with\nrespect to gravity. By computing the mean and fluctuation velocities of grains,\nwe reveal that the mixing layer results from the competition between\nsegregation by kinetic sieving and circulation promoted by the fluid flow. We\nalso observe worse fluidization as the angle relative to gravity increases,\naccounting then for the non-monotonic behavior. Our results bring new insights\ninto mixing and segregation in polydisperse beds, which can be explored for\nprocessing powders in industry.",
        "positive": "Self-Assembly of Liquid Crystals in Nanoporous Solids for Adaptive\n  Photonic Metamaterials: Nanoporous media exhibit structures significantly smaller than the\nwavelengths of visible light and can thus act as photonic metamaterials. Their\noptical functionality is not determined by the properties of the base\nmaterials, but rather by tailored, multiscale structures, in terms of precise\npore shape, geometry, and orientation. Embedding liquid crystals in pore space\nprovides additional opportunities to control light-matter interactions at the\nsingle-pore, meta-atomic scale. Here, we present temperature-dependent 3D\nreciprocal space mapping using synchrotron-based X-ray diffraction in\ncombination with high-resolution birefringence experiments on disk-like\nmesogens (HAT6) imbibed in self-ordered arrays of parallel cylindrical pores 17\nto 160 nm across in monolithic anodic aluminium oxide (AAO). In agreement with\nMonte Carlo computer simulations we observe a remarkably rich self-assembly\nbehaviour, unknown from the bulk state. It encompasses transitions between the\nisotropic liquid state and discotic stacking in linear columns as well as\ncircular concentric ring formation perpendicular and parallel to the pore axis.\nThese textural transitions underpin an optical birefringence functionality,\ntuneable in magnitude and in sign from positive to negative via pore size, pore\nsurface-grafting and temperature. Our study demonstrates that the advent of\nlarge-scale, self-organised nanoporosity in monolithic solids along with\nconfinement-controllable phase behaviour of liquid-crystalline matter at the\nsingle-pore scale provides a reliable and accessible tool to design materials\nwith adjustable optical anisotropy, and thus offers versatile pathways to\nfine-tune polarisation-dependent light propagation speeds in materials. Such a\ntailorability is at the core of the emerging field of transformative optics,\nallowing, e.g., adjustable light absorbers and extremely thin metalenses."
    },
    {
        "anchor": "Femtosecond laser produced periodic plasma in a colloidal crystal probed\n  by XFEL radiation: With the rapid development of short-pulse intense laser sources, studies of\nmatter under extreme irradiation conditions enter further unexplored regimes.\nIn addition, an application of X-ray Free- Electron Lasers (XFELs), delivering\nintense femtosecond X-ray pulses allows to investigate sample evolution in IR\npump - X-ray probe experiments with an unprecedented time resolution. Here we\npresent the detailed study of periodic plasma created from the colloidal\ncrystal. Both experimental data and theory modeling show that the periodicity\nin the sample survives to a large extent the extreme excitation and shock wave\npropagation inside the colloidal crystal. This feature enables probing the\nexcited crystal, using the powerful Bragg peak analysis, in contrast to the\nconventional studies of dense plasma created from bulk samples for which\nprobing with Bragg diffraction technique is not possible. X-ray diffraction\nmeasurements of excited colloidal crystals may then lead towards a better\nunderstanding of matter phase transitions under extreme irradiation conditions.",
        "positive": "Predicting dynamic heterogeneity in glass-forming liquids by\n  physics-inspired machine learning: We introduce GlassMLP, a machine learning framework using physics-inspired\nstructural input to predict the long-time dynamics in deeply supercooled\nliquids. We apply this deep neural network to atomistic models in 2D and 3D.\nIts performance is better than the state of the art while being more\nparsimonious in terms of training data and fitting parameters. GlassMLP\nquantitatively predicts four-point dynamic correlations and the geometry of\ndynamic heterogeneity. Transferability across system sizes allows us to\nefficiently probe the temperature evolution of spatial dynamic correlations,\nrevealing a profound change with temperature in the geometry of rearranging\nregions."
    },
    {
        "anchor": "Correlated diffusion of membrane proteins and their effect on membrane\n  viscosity: We extend the Saffman theory of membrane hydrodynamics to account for the\ncorrelated motion of membrane proteins, along with the effect of protein\nconcentration on that correlation and on the response of the membrane to\nstresses. Expressions for the coupling diffusion coefficients of protein pairs\nand their concentration dependence are derived in the limit of small protein\nsize relative to the inter-protein separation. The additional role of membrane\nviscosity as determining the characteristic length scale for membrane response\nleads to unusual concentration effects at large separation -- the transverse\ncoupling increases with protein concentration, whereas the longitudinal one\nbecomes concentration-independent.",
        "positive": "Understanding the approximations of mode-coupling theory for sheared\n  steady states of colloids: The lack of clarity of various mode-coupling theory (MCT) approximations,\neven in equilibrium,makes it hard to understand the relation between various\nMCT approaches for sheared steady states as well as their regime of validity.\nHere we try to understand these approximations indirectly by deriving the MCT\nequations through two different approaches for a colloidal system under shear,\nfirst, through a microscopic approach, as suggested by Zaccarelli et al, and\nsecond, through fluctuating hydrodynamics, where the approximations used in the\nderivation are quite clear. The qualitative similarity of our theory with a\nnumber of existing theories show that linear response theory might play a role\nin various approximations employed in deriving those theories and one needs to\nbe careful while applying them for systems arbitrarily far away from\nequilibrium, such as a granular system or when shear is very strong. As a\nbyproduct of our calculation, we obtain the extension of Yvon-Born-Green (YBG)\nequation for a sheared system and under the assumption of random-phase\napproximation, the YBG equation yields the distorted structure factor that was\nearlier obtained through different approaches."
    },
    {
        "anchor": "Hybrid Dynamic Density Functional Theory for Polymer Melts and Blends: We propose a high-speed and accurate hybrid dynamic density functional theory\nfor the computer simulations of the phase separation processes of polymer melts\nand blends. The proposed theory is a combination of the dynamic self-consistent\nfield (SCF) theory and a time-dependent Ginzburg-Landau type theory with the\nrandom phase approximation (GRPA). The SCF theory is known to be accurate in\nevaluating the free energy of the polymer systems in both weak and strong\nsegregation regions although it has a disadvantage of the requirement of a\nconsiderable amount of computational cost. On the other hand, the GRPA theory\nhas an advantage of much smaller amount of required computational cost than the\nSCF theory while its applicability is limited to the weak segregation region.\nTo make the accuracy of the SCF theory and the high-performance of the GRPA\ntheory compatible, we adjust the chemical potential of the GRPA theory by using\nthe SCF theory every constant time steps in the dynamic simulations. The\nperformance of the GRPA and the hybrid theories is tested by using several\nsystems composed of an A/B homopolymer, an AB diblock copolymer, or an ABC\ntriblock copolymer. Using the hybrid theory, we succeeded in reproducing the\nmetastable complex phase-separated domain structures of an ABC triblock\ncopolymer observed by experiments.",
        "positive": "Phase separation in a binary mixture confined between symmetric parallel\n  plates: Capillary condensation transition near the bulk critical point: We investigate phase separation of near-critical binary mixtures between\nparallel symmetric walls in the strong adsorption regime. We take into account\nthe renormalization effect due to the critical fluctuations using the recent\nlocal functional theory [J. Chem. Phys. 136, 114704 (2012)]. In statics, a van\nder Waals loop is obtained in the relation between the average order parameter\n$<psi>$ in the film and the chemical potential when the temperature $T$ is\nlower than the film critical temperature $T_c^{ca}$ (in the case of an upper\ncritical solution temperature). In dynamics, we lower $T$ below the capillary\ncondensation line from above $T_c^{ca}$. We calculate the subsequent\ntime-development assuming no mass exchange between the film and the reservoir.\nIn the early stage, the order parameter $psi$ changes only in the direction\nperpendicular to the walls. For sufficiently deep quenching, such\none-dimensional profiles become unstable with respect to the fluctuations\nvarying in the lateral directions. The late-stage coarsening is then\naccelerated by the hydrodynamic interaction. A pancake domain of the phase\ndisfavored by the walls finally appears in the middle of the film."
    },
    {
        "anchor": "Capillary assemblies in a rotating magnetic field: Small objects floating on a fluid have a tendency to aggregate due to\ncapillary forces. This effect has been used, with the help of a magnetic\ninduction field, to assemble submillimeter metallic spheres into a variety of\nstructures, whose shape and size can be tuned. Under time-varying fields, these\nassemblies can propel themselves due to a breaking of time reversal symmetry in\ntheir adopted shapes. In this article, we study the influence of an in-plane\nrotation of the magnetic field on these structures. Various rotational modes\nhave been observed with different underlying mechanisms. The magnetic\nproperties of the particles cause them to rotate individually. Dipole-dipole\ninteractions in the assembly can cause the whole structure to align with the\nfield. Finally, non-reciprocal deformations can power the rotation of the\nassembly. Symmetry plays an important role in the dynamics, as well as the\nfrequency and amplitude of the applied field. Understanding the interplay of\nthese effects is essential, both to explain previous observations and to\ndevelop new functions for these assemblies.",
        "positive": "Non-equilibrium clustering of self-propelled rods: Motivated by aggregation phenomena in gliding bacteria, we study collective\nmotion in a twodimensional model of active, self-propelled rods interacting\nthrough volume exclusion. In simulations with individual particles, we find\nthat particle clustering is facilitated by a sufficiently large packing\nfraction (eta) or length-to-width ratio (kappa). The transition to clustering\nin simulations is well captured by a mean-field model for the cluster size\ndistribution, which predicts that the transition values kappa_c of the aspect\nratio for a fixed packing fraction is given by kappa_c = C/eta - 1 where C is a\nconstant."
    },
    {
        "anchor": "Robust Prediction of Force Chains in Jammed Solids using Graph Neural\n  Networks: Force chains, which are quasi-linear self-organised structures carrying large\nstresses, are ubiquitous in jammed amorphous materials, such as granular\nmaterials, foams, emulsions or even assemblies of cells. Predicting where they\nwill form upon mechanical deformation is crucial in order to describe the\nphysical properties of such materials, but remains an open question. Here we\ndemonstrate that graph neural networks (GNN) can accurately infer the location\nof these force chains in frictionless materials from the local structure prior\nto deformation, without receiving any information about the inter-particle\nforces. Once trained on a prototypical system, the GNN prediction accuracy\nproves to be robust to changes in packing fraction, mixture composition, amount\nof deformation, and the form of the interaction potential. The GNN is also\nscalable, as it can make predictions for systems much larger than those it was\ntrained on. Our results and methodology will be of interest for experimental\nrealizations of granular matter and jammed disordered systems, e.g. in cases\nwhere direct visualisation of force chains is not possible or contact forces\ncannot be measured.",
        "positive": "Contact angle saturation in electrowetting: Injection of ions into the\n  surrounding media: We use the Poisson-Boltzmann theory to predict contact angle saturation of\naqueous droplets in electrowetting. Our theory predicts that injection of ions\nfrom the droplet into its surrounding medium is responsible for the deviation\nof the apparent contact angle from the Young-Lippmann equation for large\napplied voltages. The ion injection substantially decreases the Maxwell stress\nand increases the osmotic pressure at the interface between the two media,\nleading to saturation of the apparent contact angle. Moreover, we find that the\ncontact angle does not saturate, but only has a broad minimum that increases\nagain upon further increase of the applied voltage, in agreement with\nexperiments."
    },
    {
        "anchor": "Networks: The two approaches to analyzing the large strain behavior of rubbery networks\nare phenomenologically, using strain energy functions drawn from continuum\nmechanics, and molecular models, which apply statistical mechanics to compute\nthe effect of chain orientation on the entropy. The early rubber elasticity\nmodels ignored intermolecular interactions, whereas later developments\n(\"constraint models\") included the effect of entanglements or steric\nconstraints on the mechanical stress. These constitutive equations for rubber\nelasticity are compared to experimental results, and the connection of network\nelasticity to the relaxation behaviour is discussed. For conventional\nelastomers there is a compromise between stiffness and strength. Different\nmethods to circumvent this limitation are described. Examples are given of the\nproperties obtained with novel network architectures, including\ninterpenetrating networks, double networks, bimodal networks, miscible\nheterogeneous networks, and deswollen networks.",
        "positive": "A new algorithm for contact angle estimation in molecular dynamics\n  simulations: It is important to study contact angle of a liquid on a solid surface to\nunderstand its wetting properties, capillarity and surface interaction energy.\nWhile performing transient molecular dynamics (MD) simulations it requires\ncalculating the time evolution of contact angle. This is a tedious effort to do\nmanually or with image processing algorithms. In this work we propose a new\nalgorithm to estimate contact angle from MD simulations directly and in a\ncomputationally efficient way. This algorithm segregates the droplet molecules\nfrom the vapor molecules using Mahalanobis distance (MND) technique. Then the\ndensity is smeared onto a 2D grid using 4th order B-spline interpolation\nfunction. The vapor liquid interface data is estimated from the grid using\ndensity filtering. With the interface data a circle is fitted using Landau\nmethod. The equation of this circle is solved for obtaining the contact angle.\nThis procedure is repeated by rotating the droplet about the vertical axis. We\nhave applied this algorithm to a number of studies (different potentials and\nthermostat methods) which involves the MD simulation of water."
    },
    {
        "anchor": "On the thermopower of ionic conductor and ionic capacitors: We theoretically study the thermoelectric response of ionic conductors to an\napplied temperaturegradient. As a main result we find that open and closed\nsystems with respect to charge exchange,result in different expressions for the\nthermopower which may even take opposite signs. For theexperimentally most\nrelevant zero-current steady state, we show that the thermopower of ionic\nconductorsdoes not depend on the mobilities, contrary to what is known for\nmetals and semiconductors.The different behavior of ionic and electronic\nconductors is traced back to the unlike conservationlaws for ionic carriers and\nelectron-hole pairs.",
        "positive": "Influence of primary particle density in the morphology of agglomerates: Agglomeration processes occur in many different realms of science such as\ncolloid and aerosol formation or formation of bacterial colonies. We study the\ninfluence of primary particle density in agglomerate structure using\ndiffusion-controlled Monte Carlo simulations with realistic space scales\nthrough different regimes (DLA and DLCA). The equivalence of Monte Carlo time\nsteps to real time scales is given by Hirsch's hydrodynamical theory of\nBrownian motion. Agglomerate behavior at different time stages of the\nsimulations suggests that three indices (fractal exponent, coordination number\nand eccentricity index) characterize agglomerate geometry. Using these indices,\nwe have found that the initial density of primary particles greatly influences\nthe final structure of the agglomerate as observed in recent experimental\nworks."
    },
    {
        "anchor": "Phase diagram of heteronuclear Janus dumbbells: Using Aggregation-Volume-Bias Monte Carlo simulations along with Successive\nUmbrella Sampling and Histogram Re-weighting, we study the phase diagram of a\nsystem of dumbbells formed by two touching spheres having variable sizes, as\nwell as different interaction properties. The first sphere ($h$) interacts with\nall other spheres belonging to different dumbbells with a hard-sphere\npotential. The second sphere ($s$) interacts via a square-well interaction with\nother $s$ spheres belonging to different dumbbells and with a hard-sphere\npotential with all remaining $h$ spheres. We focus on the region where the $s$\nsphere is larger than the $h$ sphere, as measured by a parameter $1\\le\n\\alpha\\le 2 $ controlling the relative size of the two spheres.\n  As $\\alpha \\to 2$ a simple fluid of square-well spheres is recovered, whereas\n$\\alpha \\to 1$ corresponds to the Janus dumbbell limit, where the $h$ and $s$\nspheres have equal sizes. Many phase diagrams falling into three classes are\nobserved, depending on the value of $\\alpha$. The $1.8 \\le \\alpha \\le 2$ is\ndominated by a gas-liquid phase separation very similar to that of a pure\nsquare-well fluid with varied critical temperature and density. When $1.3 \\le\n\\alpha \\le 1.8$ we find a progressive destabilization of the gas-liquid phase\ndiagram by the onset of self-assembled structures, that eventually lead to a\nmetastability of the gas-liquid transition below $\\alpha=1.2$.",
        "positive": "Helical Nanofilaments and the High Chirality Limit of Smectics-A: Liquid crystalline systems exhibiting both macroscopic chirality and smectic\norder experience frustration resulting in mesophases possessing complex\nthree-dimensional order. In the twist-grain-boundary phase, defect lattices\nmediate the propagation of twist throughout the system. We propose a new chiral\nsmectic structure composed of a lattice of chiral bundles as a model of the\nhelical nanofilament (B4) phase of bent core smectics."
    },
    {
        "anchor": "Onset of Plasticity in Thin Polystyrene Films: Polymer glasses have numerous advantageous mechanical properties in\ncomparison to other materials. One of the most useful is the high degree of\ntoughness that can be achieved due to significant yield occurring in the\nmaterial. Remarkably, the onset of plasticity in polymeric materials is very\npoorly quantified, despite its importance as the ultimate limit of purely\nelastic behavior. Here we report the results of a novel experiment which is\nextremely sensitive to the onset of yield and discuss its impact on measurement\nand elastic theory. In particular, we use an elastic instability to locally\nbend and impart a \\textit{local} tensile stress in a thin, glassy polystyrene\nfilm, and directly measure the resulting residual stress caused by the bending.\nWe show that plastic failure is initiated at extremely low strains, of order\n$10^{-3}$ for polystyrene. Not only is this critical strain found to be small\nin comparison to bulk measurement, we show that it is influenced by thin film\nconfinement - leading to an increase in the critical strain for plastic failure\nas film thickness approaches zero.",
        "positive": "Corner singularities and shape of stretched elastic sheets: We investigate the deformation of a longitudinally stretched rectangular\nsheet which is clamped at two opposite boundaries and free otherwise with\nexperiments, numerical analysis and asymptotic analysis of the biharmonic\nelastic equation governing their planar equilibrium configurations. The\ndisplacement field of the sheet is measured by tracking embedded fluorescent\ntracers with a digital image correlation (DIC) technique. The experiments and\nnumerical finite element analysis (FEA) are found to be in overall good\nagreement except at the very corners where large deformations occur. We find\nthat the deformed sheet can be broadly divided into a uniaxially stretched\ncentral region and two clamp dominated side regions. A subregion characterized\nby a diverging stress can be identified at each of the four clamped-free\ncorners within the clamp dominated region. We postulate that the divergence at\nthe corners is regularized by nonlinear elastic deformations occurring in this\nsubregion at the very corners and provide a nontrivial scaling for its size.\nWithin the intermediate corner dominated subregion, measured displacements grow\nwith distance $r$ from the corners as $r^{\\alpha}$, with power $\\alpha < 1$\nconsistent with the development of stress singularities at the intersection of\nthe free and clamped edges."
    },
    {
        "anchor": "Simulation of the RAFT polymerization in 3D: steric restrictions and\n  incompatibility between species: In this work we developed a RAFT polymerization model taking into account the\nmain reactions of the experimental RAFT process and implemented that model in\ndissipative particle dynamics (DPD). With a help of a kinetic model based on\nthe same reaction routine, we investigated the question of how to simulate\nrealistic reactions using such models. We showed that a simultaneous M-fold\nincrease of the initiation probability $p_{i}$ and an M-fold decrease of the\ntermination probability $p_{t}$ does not result in significant changes in the\nchain length distribution. If the RAFT/initiator ratio is small, a simplified\nmodel with no termination and immediate radical formation can be used with good\nenough accuracy. After that we directly compared the reaction behavior within\nthe kinetic model and DPD. We showed that steric restrictions, which were not\npresent in the kinetic model, can introduce noticeable changes in the system\nbehavior. Finally, we studied the influence of the incompatibility on the RAFT\npolymerization process on an example classical implementation of\npolymerization-induced self-assembly (PISA). We showed that in systems with\nincompatible species number of activation-deactivation cycles does not always\nreflect the dispersity of the resulting chain ensemble. Moreover, we\ndemonstrated that specifically the incompatibility between the RAFT end group\nand other species can have a large effect on the polymerization results.",
        "positive": "Polystyrene grafting from silica nanoparticles via\n  Nitroxide-Mediated-Polymerization (NMP): synthesis and SANS analysis with\n  contrast variation method: We present a new convenient and efficient \"grafting from\" method to obtain\nwell defined polystyrene (PS) silica nanoparticles. The method, based on\nNitroxide-Mediated Polymerization (NMP), consists to bind covalently the\nalkoxyamine, which acts as initiator controller agent, at the silica\nnanoparticles surface in two steps. The first step is a reaction between the\naminopropylsilane and the silica particles in order to functionalize the\nparticles surface with amino group. In a second step, the\ninitiating-controlling alkoxyamine moiety is introduced via an over grafting\nreaction between the amino group and the N-hydroxysuccinimide based MAMA-SG1\nactivated ester. To simplify both their chemical transformation and the\npolymerization step, the native silica particles, initially dispersed in water,\nhave been transferred in an organic solvent, the dimethylacetamide, which is\nalso a good solvent for the polystyrene. The synthesis parameters have been\noptimized for grafting density, conversion rates, and synthesis reproducibility\nwhile keeping the colloidal stability and to avoid any aggregation of silica\nparticles induced by the inter-particles interaction evolution during the\nsynthesis. After synthesis, the final grafted objects have been purified and\nthe non-grafted polymer chains formed in the solvent have been washed out by\nultra filtration. Then the particles have been studied using Small angle\nNeutron Scattering (SANS) coupled to neutron contrast variation method. To\noptimize the contrast conditions, both hydrogenated and deuterated monomers\nhave been used for the synthesis. A refined fitting analysis based on the\ncomparison on two models, a basic core-shell and the Gaussian Pedersen model,\nenables us to fit nicely the experimental data for both the hydrogenated and\ndeuterated grafted case. Differences are seen between grafting of normal or\ndeuterated chains which can be due to monomer reactivity or to neutron contrast\neffect variations. The synthesis and the characterization method established in\nthis work constitute a robust and reproducible way to design well defined\ngrafted polymer nanoparticles. These objects will be incorporated in polymer\nmatrices in a further step to create Nanocomposites for polymer reinforcement."
    },
    {
        "anchor": "Rheophysics of dense granular materials : Discrete simulation of plane\n  shear flows: We study the steady plane shear flow of a dense assembly of frictional,\ninelastic disks using discrete simulation and prescribing the pressure and the\nshear rate. We show that, in the limit of rigid grains, the shear state is\ndetermined by a single dimensionless number, called inertial number I, which\ndescribes the ratio of inertial to pressure forces. Small values of I\ncorrespond to the quasi-static regime of soil mechanics, while large values of\nI correspond to the collisional regime of the kinetic theory. Those shear\nstates are homogeneous, and become intermittent in the quasi-static regime.\nWhen I increases in the intermediate regime, we measure an approximately linear\ndecrease of the solid fraction from the maximum packing value, and an\napproximately linear increase of the effective friction coefficient from the\nstatic internal friction value. From those dilatancy and friction laws, we\ndeduce the constitutive law for dense granular flows, with a plastic Coulomb\nterm and a viscous Bagnold term. We also show that the relative velocity\nfluctuations follow a scaling law as a function of I. The mechanical\ncharacteristics of the grains (restitution, friction and elasticity) have a\nvery small influence in this intermediate regime. Then, we explain how the\nfriction law is related to the angular distribution of contact forces, and why\nthe local frictional forces have a small contribution to the macroscopic\nfriction. At the end, as an example of heterogeneous stress distribution, we\ndescribe the shear localization when gravity is added.",
        "positive": "Solvent quality dependent osmotic pressure of polymer solutions in two\n  dimensions: Confined in two dimensional planes, polymer chains comprising dense monolayer\nsolution are segregated from each other due to topological interaction.\nAlthough the segregation is inherent in two dimensions (2D), the solution may\ndisplay different properties depending on the solvent quality. Among others, it\nis well known in both theory and experiment that the osmotic pressure ($\\Pi$)\nin the semi-dilute regime displays solvent quality-dependent increases with the\narea fraction ($\\phi$) (or monomer concentration, $\\rho$), that is, $\\Pi\\sim\n\\phi^3$ for good solvent and $\\Pi\\sim \\phi^8$ for $\\Theta$ solvent. The osmotic\npressure can be associated with the Flory exponent (or the correlation length\nexponent) for the chain size and the pair distribution function of monomers;\nhowever, they do not necessarily offer a detailed microscopic picture leading\nto the difference. To gain microscopic understanding into the different surface\npressure isotherms of polymer solution under the two distinct solvent\nconditions, we study the chain configurations of polymer solution based on our\nnumerical simulations that semi-quantitatively reproduce the expected scaling\nbehaviors. Notably, at the same value of $\\phi$, polymer chains in $\\Theta$\nsolvent occupy the surface in a more \\emph{inhomogeneous} manner than the\nchains in good solvent, yielding on average a greater and more heterogeneous\ninterstitial void size, which is related to the fact that the polymer in\n$\\Theta$ solvent has a greater correlation length. The polymer configurations\nand interstitial voids visualized and quantitatively analyzed in this study\noffer microscopic understanding to the origin of the solvent quality dependent\nosmotic pressure of 2D polymer solutions."
    },
    {
        "anchor": "Controlled motion of Janus particles in periodically phase-separating\n  binary fluids: We numerically investigate the propelled motions of a Janus particle in a\nperiodically phase-separating binary fluid mixture. In this study, the surface\nof the particle tail prefers one of the binary fluid components and the\nparticle head is neutral in the wettability. During the demixing period, the\nmore wettable phase is selectively adsorbed to the particle tail. Growths of\nthe adsorbed domains induce the hydrodynamic flow in the vicinity of the\nparticle tail, and this asymmetric pumping flow drives the particle toward the\nparticle head. During the mixing period, the particle motion almost ceases\nbecause the mixing primarily occurs via diffusion and the resulting\nhydrodynamic flow is negligibly small. Repeating this cycle unboundedly moves\nthe Janus particle toward the head. The dependencies of the composition and the\nrepeat frequency on the particle motion are discussed.",
        "positive": "Polarized Brillouin Scattering in Salol: Effects of Rotation-Translation\n  Coupling: We have studied the 90 degree VV-polarized Brillouin scattering spectrum of\nthe molecular glassformer salol and observed a previously unnoticed VV-dip\nfeature at low frequencies for temperatures above 300K. This new feature is a\nconsequence of rotation-translation coupling, as recently predicted by Pick,\nFranosch et al [Eur. Phys. J. B 31, 217, 229 (2003)], who showed its\nrelationship to the Rytov dip that occurs in the corresponding VH spectrum. The\nanalysis of the spectra shows good agreement with the theoretical predictions."
    },
    {
        "anchor": "Theory of spiral wave dynamics in weakly excitable media: asymptotic\n  reduction to a kinematic model and applications: In a weakly excitable medium, characterized by a large threshold stimulus,\nthe free end of an isolated broken plane wave (wave tip) can either rotate\n(steadily or unsteadily) around a large excitable core, thereby producing a\nspiral pattern, or retract causing the wave to vanish at boundaries. An\nasymptotic analysis of spiral motion and retraction is carried out in this\nweakly excitable large core regime starting from the free-boundary limit of the\nreaction-diffusion models, valid when the excited region is delimited by a thin\ninterface. The wave description is shown to naturally split between the tip\nregion and a far region that are smoothly matched on an intermediate scale.\nThis separation allows us to rigorously derive an equation of motion for the\nwave tip, with the large scale motion of the spiral wavefront slaved to the\ntip. This kinematic description provides both a physical picture and exact\npredictions for a wide range of wave behavior, including: (i) steady rotation\n(frequency and core radius), (ii) exact treatment of the meandering instability\nin the free-boundary limit with the prediction that the frequency of unstable\nmotion is half the primary steady frequency (iii) drift under external actions\n(external field with application to axisymmetric scroll ring motion in\nthree-dimensions, and spatial or/and time-dependent variation of excitability),\nand (iv) the dynamics of multi-armed spiral waves with the new prediction that\nsteadily rotating waves with two or more arms are linearly unstable. Numerical\nsimulations of FitzHug-Nagumo kinetics are used to test several aspects of our\nresults. In addition, we discuss the semi-quantitative extension of this theory\nto finite cores and pinpoint mathematical subtleties related to the thin\ninterface limit of singly diffusive reaction-diffusion models.",
        "positive": "Effects of rigid or adaptive confinement on colloidal self-assembly.\n  Fixed vs. fluctuating number of confined particles: The effects of confinement on colloidal self-assembly in the case of fixed\nnumber of confined particles are studied in the one dimensional lattice model\nsolved exactly in the Grand Canonical Ensemble (GCE) in [J. P\\k{e}kalski et al.\nJ. Chem. Phys. 142, 014903 (2015)]. The model considers a pair interaction\ndefined by a short-range attraction plus a longer-range repulsion. We consider\nthermodynamic states corresponding to self-assembly into clusters. Both, fixed\nand adaptive boundaries are studied. For fixed boundaries, there are particular\nstates in which, for equal average densities, the number of clusters in the GCE\nis larger than in the Canonical Ensemble. The dependence of pressure on density\nhas a different form when the system size changes with fixed number of\nparticles and when the number of particles changes with fixed size of the\nsystem. In the former case the pressure has a nonmonotonic dependence on the\nsystem size. The anomalous increase of pressure for expanding system is\naccompanied by formation of a larger number of smaller clusters. In the case of\nelastic confining surfaces we observe a bistability, i.e. two significantly\ndifferent system sizes occur with almost the same probability. The mechanism of\nthe bistability in the closed system is different to that of the case of\npermeable walls, where the two equilibrium system sizes correspond to a\ndifferent number of particles."
    },
    {
        "anchor": "Structural control of elastic moduli in ferrogels and the importance of\n  non-affine deformations: One of the central appealing properties of magnetic gels and elastomers is\nthat their elastic moduli can reversibly be adjusted from outside by applying\nmagnetic fields. The impact of the internal magnetic particle distribution on\nthis effect has been outlined and analyzed theoretically. In most cases,\nhowever, affine sample deformations are studied and often regular particle\narrangements are considered. Here we challenge these two major simplifications\nby a systematic approach using a minimal dipole-spring model. Starting from\ndifferent regular lattices, we take into account increasingly randomized\nstructures, until we finally investigate an irregular texture taken from a real\nexperimental sample. On the one hand, we find that the elastic tunability\nqualitatively depends on the structural properties, here in two spatial\ndimensions. On the other hand, we demonstrate that the assumption of affine\ndeformations leads to increasingly erroneous results the more realistic the\nparticle distribution becomes. Understanding the consequences of the\nassumptions made in the modeling process is important on our way to support an\nimproved design of these fascinating materials.",
        "positive": "Soft Lithography using Nectar Droplets: In spite of significant advances in replication technologies, methods to\nproduce well-defined three dimensional structures are still at its infancy.\nSuch a limitation would be evident if we were to produce a large array of\nsimple and, especially, compound convex lenses, also guaranteeing that their\nsurfaces would be molecularly smooth. Here, we report a novel method to produce\nsuch structures by cloning the 3D shape of nectar drops, found widely in\nnature, using conventional soft lithography.The elementary process involves\ntransfer of a thin patch of the sugar solution coated on a glass slide onto a\nhydrophobic substrate on which this patch evolves into a microdroplet. Upon the\nabsorption of water vapor, such a microdroplet grows linearly with time and its\nfinal size can be controlled by varying its exposure time to water vapor. At\nany stage of the evolution of the size of the drop, its shape can be cloned\nonto a soft elastomer by following the well-known methods of molding and\ncrosslinking the same. A unique new science that emerges in our attempt to\nunderstand the transfer of the sugar patch and its evolution to a spherical\ndrop is the elucidation of the mechanics underlying the contact of a deformable\nsphere against a solid support intervening a thin liquid film. A unique aspect\nof this work is to demonstrate that higher level structures can also be\ngenerated by transferring even smaller nucleation sites on the surface of the\nprimary lenses and then allowing them to grow by absorption of water vapor.\nWhat results at the end is either a well-controlled distribution of smooth\nhemispherical lenses or compound structures that could have potential\napplications in the fundamental studies of contact mechanics, wettability and\neven in optics."
    },
    {
        "anchor": "Structure and Electrical Properties of DNA Nanotubes Embedded in Lipid\n  Bilayer Membranes: Engineering the synthetic nanopores through lipid bilayer membrane to access\nthe interior of a cell is a long persisting challenge in biotechnology. Here,\nwe demonstrate the stability and dynamics of a tile-based 6-helix DNA nanotube\n(DNT) embedded in POPC lipid bilayer using the analysis of 0.2 microsecond long\nequilibrium MD simulation trajectories. We observe that the head groups of the\nlipid molecules close to the lumen cooperatively tilt towards the hydrophilic\nsugar-phosphate backbone of DNA and form a toroidal structure around the patch\nof DNT protruding in the membrane. Further, we explore the effect of ionic\nconcentrations to the in-solution structure and stability of the lipid-DNT\ncomplex. Transmembrane ionic current measurements for the constant electric\nfield MD simulation provide the I-V characteristics of the water filled DNT\nlumen in lipid membrane. With increasing salt concentrations, the measured\nvalues of transmembrane ionic conductance of the porous DNT lumen vary from 4.3\nnS to 20.6 nS. Simulations of the DNTs with ssDNA and dsDNA overhangs at the\nmouth of the pore show gating effect with remarkable difference in the\ntransmembrane ionic conductivities for open and close state nanopores.",
        "positive": "Probing the nonequilibrium dynamics of stress, orientation and\n  entanglements in polymer melts with orthogonal interrupted shear simulations: Both entangled and unentangled polymer melts exhibit stress overshoots when\nsubject to shearing flow. The size of the overshoot depends on the applied\nshear rate and is related to relaxation mechanisms such as reptation, chain\nstretch and convective constraint release. Previous experimental work shows\nthat melts subjected to interrupted shear flows exhibit a smaller overshoot\nwhen sheared after partial relaxation. This has been shown to be consistent\nwith predictions by constitutive models. Here, we report molecular dynamics\nsimulations of interrupted shear of polymer melts where the shear flow after\nthe relaxation stage is orthogonal to the original applied flow. We observe\nthat, for a given relaxation time, the size of the stress overshoot under\northogonal interrupted shear is larger than observed during parallel\ninterrupted shear, which is not captured by constitutive models. Differences in\nmaxima are also observed for overshoots in the first normal stress and chain\nend-to-end distance. We also show that measurements of the average number of\nentanglements per chain and average orientation at different scales along the\nchain are affected by the change in shear direction, leading to non-monotonic\nrelaxation of the off-diagonal components of orientation and an appearance of a\n'double peak' in the average number of entanglements during the transient. We\npropose that such complex behavior of entanglements is responsible for the\nincrease in the overshoots of stress components, and that models of the\ndynamics of entanglements might be improved upon by considering a tensorial\nmeasurement of entanglements that can be coupled to orientation."
    },
    {
        "anchor": "Universal wrinkling of supported elastic rings: An exactly solvable family of models describing the wrinkling of\nsubstrate-supported inextensible elastic rings under compression is identified.\nThe resulting wrinkle profiles are shown to be related to the buckled states of\nan unsupported ring and are therefore universal. Closed analytical expressions\nfor the resulting universal shapes are provided, including the one-to-one\nrelations between the pressure and tension at which these emerge. The\nanalytical predictions agree with numerical continuation results to within\nnumerical accuracy, for a large range of parameter values, up to the point of\nself-contact.",
        "positive": "Controlling the volume fraction of glass-forming colloidal suspensions\n  using thermosensitive host `mesogels': The key parameter controlling the glass transition of colloidal suspensions\nis $\\varphi$, the fraction of the sample volume occupied by the particles.\nUnfortunately, changing $\\varphi$ by varying an external parameter,\n\\textit{e.g.} temperature $T$ as in molecular glass formers, is not possible,\nunless one uses thermosensitive colloidal particles, like the popular\npoly(N-isopropylacrylamide) (PNiPAM) microgels. These however have several\ndrawbacks, including high deformability, osmotic deswelling and\ninterpenetration, which complicate their use as a model system to study the\ncolloidal glass transition. Here, we propose a new system consisting of a\ncolloidal suspension of non-deformable spherical silica nanoparticles, in which\nPNiPAM hydrogel spheres of ~$100-200 \\mu m$ size are suspended. These\nnon-colloidal `mesogels' allow for controlling the sample volume effectively\navailable to the silica nanoparticles and hence their $\\varphi$, thanks to the\n$T$-induced change in mesogels volume. Using optical microscopy, we first show\nthat the mesogels retain their ability to change size with $T$ when suspended\nin Ludox suspensions, similarly as in water. We then show that their size is\nindependent of the sample thermal history, such that a well-defined, reversible\nrelationship between $T$ and $\\varphi$ may be established. Finally, we use\nspace-resolved dynamic light scattering to demonstrate that, upon varying $T$,\nour system exhibits a broad range of dynamical behaviors across the glass\ntransition and beyond, comparable with those exhibited by a series of distinct\nsilica nanoparticle suspensions of various $\\varphi$."
    },
    {
        "anchor": "Onsager's irreversible thermodynamics of the dynamics of transient pores\n  in spherical lipid vesicles: Onsager's irreversible thermodynamics is used to perform a systematic\ndeduction of the kinetic equations governing the opening and collapse of\ntransient pores in spherical vesicles. We show that the edge tension has to be\ndetermined from the initial stage of the pore relaxation and that in the final\nstate the vesicle membrane is not completely relaxed, since the surface tension\nand the pressure difference are about $25\\%$ of its initial value. We also show\nthat the pore life-time is controlled by the solution viscosity and its opening\nis driven by the solution leak-out and the surface tension drop. The final\ncollapse is due to a non-linear interplay between the edge and the surface\ntensions together with the pressure difference. Also, we discuss the connection\nwith previous models.",
        "positive": "Surfactant Induced Catastrophic Collapse of Carbon Black Suspension used\n  in Flow Battery Application: Carbon black particles act as electronically conductive additives in the\nslurry electrodes used in electrochemical redox flow batteries. Stability and\ndispersion of the carbon black particles in a slurry electrode are critical\nparameters for its storage and the efficient functioning of the battery.\nModifying the carbon black slurry formulation with the addition of a nonionic\nsurfactant could potentially impart desired properties such as good particle\ndispersion, gravitational stability and flowability imparting better\nperformance of the flow battery. Matching the typical slurry electrode\nformulation, we dispersed carbon black particles in 1 M H$_2$SO$_4$ with volume\nfraction $\\phi$ = 0.01 to 0.06 and c$_{surf.}$ = 0, 0.05 and 0.1 M. Rheological\ninvestigation reveals that the carbon black suspensions behave like colloidal\ngels. Sedimentation kinetics of the process was measured by tracking the height\nof the particle bed over time in a cuvette using a custom camera set-up. The\nsedimentation dynamics here clearly resembled that of a gel collapse. At short\ntimes we observe fast sedimentation associated with structural collapse of the\ngel and at long times very slow sedimentation associated with compaction of the\nsediment. Addition of a nonionic surfactant (Triton X-100) to the solvent above\nCMC at $\\alpha$ (= c$_{surf.}$/c$_{CB}$) $<$ 0.7 improves particle dispersion\nand increases gel elasticity. However, for $\\alpha >$ 0.7 leads to the\nformation of a weaker gel that exhibits 'catastrophic collapse' under gravity\nand has a lower viscosity."
    },
    {
        "anchor": "Dynamics of Alpha-Helix Formation in the CSAW Model: We study the folding dynamics of polyalanine (Ala$_{20}$), a protein fragment\nwith 20 residues whose native state is a single alpha helix. We use the CSAW\nmodel (conditioned self-avoiding walk), which treats the protein molecule as a\nchain in Brownian motion, with interactions that include hydrophobic forces and\ninternal hydrogen bonding. We find that large scale structures form before\nsmall scale structures, and obtain the relevant relaxation times. We find that\nhelix nucleation occurs at two separate points on the protein chain. The\nevolution of small and large scale structures involve different mechanisms.\nWhile the former can be describe by rate equations governing the growth of\nhelical content, the latter is akin to the relaxation of an elastic solid.",
        "positive": "Dependence of Sidechain Rotamer Preference on Backbone Conformation:\n  Relative Free Energy Calculations for Valine and Leucine: Three dimensional relative free energy calculations are used to directly\ncalculate the dependence of the preferred sidechain rotamers for valine and\nleucine on the conformation of the backbone. Specifically, umbrella restrained\nmolecular dynamics calculations are used to sample all of Ramachandran space\nfor chi values surrounding the common rotameric states of leucine and valine.\nRelative free enegy slices were calculated from the biased trajectories using\nthe weighted histogram analysis method (WHAM). The slices were connected\ntogether by another set of slices perpendicular to Ramachandran space to\ndetermine the favored rotamer for a given backbone conformation. The calculated\npreferences are quite similar to those seen in the backbone-dependent rotamer\nlibrary of Dunbrack and Karplus, despite the fact that the current calculations\nneglect the effects of neighboring residues. It appears likely that these\ncalculations could be extended to calculate the optimal sidechain conformation\nfor a peptide with known backbone conformation in the context of structure\nrefinement and prediction"
    },
    {
        "anchor": "Tunable Three-Dimensional Architecture of Nematic Disclination Lines: Disclinations lines play a key role in many physical processes, from the\nfracture of materials to the formation of the early universe. Achieving\nversatile control over disclinations is key to developing novel electro-optical\ndevices, programmable origami, directed colloidal assembly, and controlling\nactive matter. Here, we introduce a theoretical framework to tailor\nthree-dimensional disclination architecture in nematic liquid crystals\nexperimentally. We produce quantitative predictions for the connectivity and\nshape of disclination lines found in nematics confined between two thinly\nspaced glass substrates with strong planar anchoring. By drawing an analogy\nbetween nematic liquid crystals and magnetostatics, we find that: i)\ndisclination lines connect defects with the same topological charge on opposite\nsurfaces, and ii) disclination lines are attracted to regions of the highest\ntwist. Using polarized light to pattern the in-plane alignment of liquid\ncrystal molecules, we test these predictions experimentally and identify\ncritical parameters that tune the disclination lines' curvature. We verify our\npredictions with computer simulations and find non-dimensional parameters\nenabling us to match experiments and simulations at different length scales.\nOur work provides a powerful method to understand and practically control\ndefect lines in nematic liquid crystals.",
        "positive": "Active particle dynamics beyond the jamming density: Many biological systems form colonies at high density. Passive granular\nsystems will be jammed at such densities, yet for the survival of biological\nsystems it is crucial that they are dynamic. We construct a phase diagram for a\nsystem of active particles interacting via Vicsek alignment, and vary the\ndensity, self-propulsion force, and orientational noise. We find that the\nsystem exhibits four different phases, characterized by transitions in the\neffective diffusion constant and in the orientational order parameter. Our\nsimulations show that there exists an optimal noise such that particles require\na minimal force to unjam, allowing for rearrangements."
    },
    {
        "anchor": "Adsorption anomalies in a 2D model of cluster-forming systems: Adsorption on a boundary line confining a monolayer of particles\nself-assembling into clusters is studied by MC simulations. We focus on a\nsystem of particles interacting via competing interaction potential in which\neffectively short-range attraction is followed by long-range repulsion,\nmimicking the so called SALR system. For the chemical potential values below\nthe order-disorder phase transition the adsorption isotherms were shown to\nundergo non-standard behavior, i. e. the adsorption exhibits a maximum upon\nstructural transition between structureless and disordered cluster fluid. In\nparticular, we have found that the adsorption decreases for increasing chemical\npotential when (i) clusters dominate over monomers in the bulk, (ii) the\ndensity profile in the direction perpendicular to the confining line exhibits\nan oscillatory decay, (iii) the correlation function in the layer near the\nadsorption wall exhibits an oscillatory decay in the direction parallel to this\nwall. Our report indicates striking differences between simple and complex\nfluid adsorption processes.",
        "positive": "Identifying the Bose glass phase: Introducing disorder into the Bose-Hubbard model at integer fillings leads to\na Bose glass phase, along with the Mott insulator and superfluid phases. We\nsuggest a new order parameter: the determinant of the one body density matrix,\nwhich is nonzero only within the Mott-insulator phase. Alongside the superfluid\nfraction, it is then possible to distinguish the three phases. The Bose glass\nphase is the only phase which has vanishing determinant and superfluid\nfraction. The vanishing of the determinant in the Bose glass phase occurs due\nto the partial fragmentation of the condensate into localized fragments, each\nwith zero superfluid response, which implies the presence of unoccupied sites\nand hence the presence of lines of zeros in the one body density matrix. In the\nsuperfluid phase, the determinant vanish for another reason - due to the\nmacroscopic occupation of a single particle state. Finally, we suggest the\nenhancement of the three body decay rate in the Bose glass phase, as an\nexperimental indicator for the presence of localized fragments."
    },
    {
        "anchor": "Microscopic origin of self-similarity in granular blast waves: The self-similar expansion of a blast wave, well-studied in air, has peculiar\ncounterparts in dense and dissipative media such as granular gases. Recent\nresults have shown that, while the traditional Taylor-von Neumann-Sedov (TvNS)\nderivation is not applicable to such granular blasts, they can nevertheless be\nwell understood via a combination of microscopic and hydrodynamic insights. In\nthis article, we provide a detailed analysis of these methods associating\nMolecular Dynamics simulations and continuum equations, which successfully\npredict hydrodynamic profiles, scaling properties and the instability of the\nself-similar solution. We also present new results for the energy conserving\ncase, including the particle-level analysis of the classic TvNS solution and\nits breakdown at higher densities.",
        "positive": "Active entanglement enables stochastic, topological grasping: Grasping, in both biological and engineered mechanisms, can be highly\nsensitive to the gripper and object morphology, as well as perception, and\nmotion planning. Here we circumvent the need for feedback or precise planning\nby using an array of fluidically-actuated slender hollow elastomeric filaments\nto actively entangle with objects that vary in geometric and topological\ncomplexity. The resulting stochastic interactions enable a unique soft and\nconformable grasping strategy across a range of target objects that vary in\nsize, weight, and shape. We experimentally evaluate the grasping performance of\nour strategy, and use a computational framework for the collective mechanics of\nflexible filaments in contact with complex objects to explain our findings.\nOverall, our study highlights how active collective entanglement of a filament\narray via an uncontrolled, spatially distributed scheme provides new options\nfor soft, adaptable grasping."
    },
    {
        "anchor": "The Chiral Dipolar Hard Sphere Model: A simple molecular model of chiral molecules is presented in this paper : the\nchiral dipolar hard sphere model. The discriminatory interaction between\nenantiomers is represented by electrostatic (or magnetic) dipoles-dipoles\ninteractions : short ranged steric repulsion are represented by hard sphere\npotential and, in each molecule, two point dipoles are located inside the\nsphere. The model is described in detail and some of its elementary properties\nare given ; in particular, it is shown that the that the knowledge of only\nthree multipole spherical components (namely : $Q_{10}$, $Q_{21}$ and $Q_{22}$)\nallows to compute all multipole spherical components of the model. Despite, the\nsimplicity of the model, it is shown also that the energy landscape of the\ninteraction between two enantiomers is quite rich, this renders systems of\nchiral dipolar hard sphere very interesting and complicated to study. Few\npreliminary Monte Carlo simulation results are also reported in the paper.\nLast, but not least, this paper is dedicated to Jean-Jacques Weis.",
        "positive": "Effects of Microstructure Formation on the Stability of Vapor Deposited\n  Glasses: Glasses formed by physical vapor deposition (PVD) are an interesting new\nclass of materials, exhibiting properties thought to be equivalent to those of\nglasses aged for thousands of years. Exerting control over the structure and\nproperties of PVD glasses formed with different types of glass-forming\nmolecules is now an emerging challenge. In this work, we study coarse grained\nmodels of organic glass formers containing fluorocarbon tails of increasing\nlength, corresponding to an increased tendency to form microstructures. We use\nsimulated PVD to examine how the presence of the microphase separated domains\nin the supercooled liquid influences the ability to form stable glasses. This\nmodel suggests that increasing molecule tail length results in decreased\nthermodynamic and kinetic stability of the molecules in PVD films. The reduced\nstability is further linked to the reduced ability of these molecules to\nequilibrate at the free surface during PVD. We find that as the tail length is\nincreased, the relaxation time near the surface of the supercooled equilibrium\nliquid films of these molecules are slowed and become essentially bulk-like,\ndue to the segregation of the fluorocarbon tails to the free surface. Surface\ndiffusion is also markedly reduced due to clustering of the molecules at the\nsurface. Based on these results, we propose a trapping mechanism where tails\nare unable to move between local phase separated domains on the relevant\ndeposition time scales."
    },
    {
        "anchor": "Numerical explorations of solvent borne adhesives: A lattice-based\n  approach to morphology formation: The internal structure of adhesive tapes determines the effective mechanical\nproperties. This holds true especially for blended systems, here consisting of\nacrylate and rubber phases. In this note, we propose a lattice-based model to\nstudy numerically the formation of internal morphologies within a\nfour-component mixture (of discrete particles) where the solvent components\nevaporate. Mimicking numerically the interaction between rubber, acrylate, and\ntwo different types of solvents, relevant for the technology of adhesive tapes,\nwe aim to obtain realistic distributions of rubber ball-shaped morphologies --\nthey play a key role in the overall functionality of those special adhesives.\nOur model incorporates the evaporation of both solvents and allows for tuning\nthe strength of two essentially different solvent-solute interactions and of\nthe temperature of the system.",
        "positive": "Effects of van der Waals forces and salt ions on the growth of water\n  films on ice and the detachment of CO$_2$ bubbles: We study the effect of salts on the thickness of wetting films on melting ice\nand interactions acting on CO$_2$ bubble near ice-water and vapor-water\ninterfaces. Governing mechanisms are the Lifshitz and the double-layer\ninteractions in the respective three-layer geometries. We demonstrate that the\nlatter depend on the Casimir--Polder interaction of the salt ions dissolved in\nwater with the respective ice, vapour and CO$_2$ interfaces, as calculated\nusing different models for their effective polarizability in water. Significant\nvariation in the predicted thickness of the equilibrium water film is observed\nfor different salt ions and when using different models for the ions'\npolarizabilities. We find that CO$_2$ bubbles are attracted towards ice-water\ninterface and repelled from the vapor-water interface"
    },
    {
        "anchor": "Drag coefficient of a liquid domain in a two-dimensional membrane: Using a hydrodynamic theory that incorporates a momentum decay mechanism, we\ncalculate the drag coefficient of a circular liquid domain of finite viscosity\nmoving in a two-dimensional membrane. We derive an analytical expression for\nthe drag coefficient which covers the whole range of domain sizes. Several\nlimiting expressions are discussed. The obtained drag coefficient decreases as\nthe domain viscosity becomes smaller with respect to the outer membrane\nviscosity. This is because the flow induced in the domain acts to transport the\nfluid in the surrounding matrix more efficiently.",
        "positive": "Formation of disclination lines near a free nematic interface: We have studied the nucleation and the physical properties of a -1/2 wedge\ndisclination line near the free surface of a confined nematic liquid crystal.\nThe position of the disclination line has been related to the material\nparameters (elastic constants, anchoring energy and favored anchoring angle of\nthe molecules at the free surface). The use of a planar model for the structure\nof the director field (whose predictions have been contrasted to those of a\nfully three-dimensional model) has allowed us to relate the experimentally\nobserved position of the disclination line to the relevant properties of the\nliquid crystals. In particular, we have been able to observe the collapse of\nthe disclination line due to a temperature-induced anchoring angle transition,\nwhich has allowed us to rule out the presence of a real disclination line near\nthe nematic/isotropic front in directional growth experiments.\n  61.30.Jf,61.30.Gd"
    },
    {
        "anchor": "Viscoelastic effects and anomalous transient levelling exponents in thin\n  films: We study theoretically the profile evolution of a thin viscoelastic film\nsupported onto a no-slip flat substrate. Due to the nonconstant initial\ncurvature at the free surface, there is a flow driven by Laplace pressure and\nmediated by viscoelasticity. In the framework of lubrication theory, we derive\na thin film equation that contains local viscoelastic stress through the\nMaxwell model. Then, considering a sufficiently regular small perturbation of\nthe free surface, we linearise the equation and derive its general solution. We\nanalyse and discuss in details the behaviour of this function. We then use it\nto study the viscoelastic evolution of a Gaussian initial perturbation through\nits transient levelling exponent. For initial widths of the profile that are\nsmaller than a characteristic length scale involving both the film thickness\nand the elastocapillary length, this exponent is shown to reach anomalously\nhigh values at the elastic-to-viscous transition. This prediction should in\nparticular be observed at sufficiently short times in experiments on thin\npolymer films.",
        "positive": "RNAlike polymer model: exact calculation on the Bethe lattice: We consider a lattice polymer model (random walk), in which the walk is\nallowed to visit lattice bonds at most twice. Such a model might have some\nrelevance to describe statistical properties of RNA molecules. In order to\nmimic base pairing, we assign an attractive energy term to each doubly-visited\nbond, and a further contribution to each pair of consecutive doubly-visited\nbonds. The latter term is expected to mimic the stacking effect, whereas no\neffect of sequence, that is, of chemical specificity, is taken into account.\nThe phase diagram is worked out exactly on a Bethe lattice, in a\ngrand-canonical formulation. In the dilute solution (single molecule) limit,\nthe system undergoes two different phase transitions, upon decreasing\ntemperature: a Thetalike collapse from a swollen \"coil\" state to a \"molten\"\nstate, with a low fraction of doubly-visited bonds, and subsequently to a\n\"paired\" state, with empty or doubly-visited bonds only. The stacking effect\ndrives the latter transition from second to first order."
    },
    {
        "anchor": "Geometric Theory of Columnar Phases on Curved Substrates: We study thin self-assembled columns constrained to lie on a curved, rigid\nsubstrate. The curvature presents no local obstruction to equally spaced\ncolumns in contrast to curved crystals for which the crystalline bonds are\nfrustrated. Instead, the vanishing compressional strain of the columns implies\nthat their normals lie on geodesics which converge (diverge) in regions of\npositive (negative) Gaussian curvature, in analogy to the focussing of light\nrays by a lens. We show that the out of plane bending of the cylinders acts as\nan effective ordering field.",
        "positive": "Hard discs under steady shear: comparison of Brownian dynamics\n  simulations and mode coupling theory: Brownian dynamics simulations of bidisperse hard discs moving in two\ndimensions in a given steady and homogeneous shear flow are presented close to\nand above the glasstransition density. The stationary structure functions and\nstresses of shear-melted glass are compared quantitatively to parameter-free\nnumerical calculations of monodisperse hard discs using mode coupling theory\nwithin the integration through transients framework. Theory qualitatively\nexplains the properties of the yielding glass but quantitatively\noverestimatesthe shear-driven stresses and structural anisotropies."
    },
    {
        "anchor": "Energy landscapes, ideal glasses, and their equation of state: Using the inherent structure formalism originally proposed by Stillinger and\nWeber [Phys. Rev. A 25, 978 (1982)], we generalize the thermodynamics of an\nenergy landscape that has an ideal glass transition and derive the consequences\nfor its equation of state. In doing so, we identify a separation of\nconfigurational and vibrational contributions to the pressure that corresponds\nwith simulation studies performed in the inherent structure formalism. We\ndevelop an elementary model of landscapes appropriate to simple liquids which\nis based on the scaling properties of the soft-sphere potential complemented\nwith a mean-field attraction. The resulting equation of state provides an\naccurate representation of simulation data for the Lennard-Jones fluid,\nsuggesting the usefulness of a landscape-based formulation of supercooled\nliquid thermodynamics. Finally, we consider the implications of both the\ngeneral theory and the model with respect to the so-called Sastry density and\nthe ideal glass transition. Our analysis shows that a quantitative connection\ncan be made between properties of the landscape and a simulation-determined\nSastry density, and it emphasizes the distinction between an ideal glass\ntransition and a Kauzmann equal-entropy condition.",
        "positive": "Spontaneous Formation of Double Emulsions at Particle-Laden Interfaces: Double emulsions, due to their compartmental structures, are essential in\nfood, agricultural, and pharmaceutical applications. Traditionally, double\nemulsifications rely on the presence of both oil-soluble and water-soluble\nsurfactants or external stimuli responsive materials and require sequential\ndroplet formation settings or unique fluidic designs. We report on unusual\nphenomenon where double emulsions are spontaneously formed as soon an aqueous\nnanoparticle dispersion is placed in contact with an oleic micellar solution.\nNanoscale water droplets nucleate in oil in the form of swollen micelles.\nNanoparticles form a water-shell encapsulating the saturated oil phase with\nswollen micelles over time. Remarkably, we find that the gradual\nsurface-activation of nanoparticles is key in self-double emulsification and\ncontrolling the emulsion intensity. We build on this new discovery and design a\nnovel system for double emulsion formation. This approach is a scalable\nself-sequential strategy for preparing core-shell double emulsions that\ndisperses nanoparticles in the opposite phase by employing micelles as\ntransport vehicles. Incorporating nanoparticles into spontaneous emulsification\nsystems opens novel routes for designing emulsion-based materials."
    },
    {
        "anchor": "Structure of electrolyte solutions at non-uniformly charged surfaces on\n  a variety of length scales: The structures of dilute electrolyte solutions close to non-uniformly charged\nplanar substrates are systematically studied within the entire spectrum of\nmicroscopic to macroscopic length scales by means of a unified classical\ndensity functional theory (DFT) approach. This is in contrast to previous\ninvestigations, which are applicable either to short or to long length scales.\nIt turns out that interactions with microscopic ranges, e.g., due to the hard\ncores of the fluid molecules and ions, have negligible influence on the\nformation of non-uniform lateral structures of the electrolyte solutions. This\npartly justifies the Debye-H\\\"uckel approximation schemes applied in previous\nstudies of that system. In general, a coupling between the lateral and the\nnormal fluid structures leads to the phenomenology that, upon increasing the\ndistance from the substrate, less details of the lateral non-uniformities\ncontribute to the fluid structure, such that ultimately only large-scale\nsurface features remain relevant. It can be expected that this picture also\napplies to other fluids characterized by several length scales.",
        "positive": "Batch versus microfluidic emulsification processes to produce whey\n  protein microgel beads from thermal or acidic gelation: Producing food-grade soft particles with controlled structure is of interest\nto elucidate the structure-properties relationship in soft-particles\nsuspensions. The aim of this work is to evaluate the ability of two elaboration\nprocesses to produce homogenous and spherical whey protein microgels with\nadjustable diameters in the range 40-100 $\\mu$m. Microgels are formed in two\nsteps: (1) emulsification of a whey protein aqueous solution in oil and (2)\ngelation of the protein solution droplets. We compare a continuous\nemulsification in a home-made microfluidic device, designed on purpose, with a\nmore simple emulsification by mixing. In addition, two gelation processes are\nstudied: a thermal gelation at 80{\\textdegree}C and an acid gelation. Results\nsshow that emulsification controls the size polydispersity (pdI<0.1 for\nmicrofluidics) while gelation controls the microgels structure and assembly.\nAcid gelation in the microfluidic device results in spherical, homogeneous\nmicrogels which properties are controlled by the process parameters."
    },
    {
        "anchor": "Continuous theory of active matter systems with metric-free interactions: We derive a hydrodynamic description of metric-free active matter: starting\nfrom self-propelled particles aligning with neighbors defined by \"topological\"\nrules, not metric zones, -a situation advocated recently to be relevant for\nbird flocks, fish schools, and crowds- we use a kinetic approach to obtain\nwell-controlled nonlinear field equations. We show that the density-independent\ncollision rate per particle characteristic of topological interactions\nsuppresses the linear instability of the homogeneous ordered phase and the\nnonlinear density segregation generically present near threshold in metric\nmodels, in agreement with microscopic simulations.",
        "positive": "Statistical self-organization of a gas of interacting walking drops in a\n  confining potential: A drop bouncing on a vertically-vibrated surface may self-propel forward by\nstanding waves and travels along a fluid interface. This system called walking\ndrop forms a non-quantum wave-particle association at the macroscopic scale.\nThe dynamics of one particle has triggered many investigations and has resulted\nin spectacular experimental results in the last decade. We investigate\nnumerically the dynamics of a gas of walkers, i.e. a large number of walking\ndrops evolving on a unbounded fluid interface in the presence of a confining\npotential acting on the particles. We show that even if the individual\ntrajectories are erratic, the system presents well-defined ordered internal\nstructure that remains invariant to parameter variations such as the number of\ndrops, the memory time and the bath radius. We rationalize such non-stationary\nself-organization in terms of the symmetry of the waves and show that\noscillatory pair potentials form a wavy collective state of active matter."
    },
    {
        "anchor": "Replica-exchange molecular dynamics simulation for supercooled liquids: We investigate to what extend the replica-exchange Monte Carlo method is able\nto equilibrate a simple liquid in its supercooled state. We find that this\nmethod does indeed allow to generate accurately the canonical distribution\nfunction even at low temperatures and that its efficiency is about 10-100 times\nhigher than the usual canonical molecular dynamics simulation.",
        "positive": "When do soft spheres become hard spheres?: The conventional (Zwanzig-Mountain) expressions for instantaneous elastic\nmoduli of simple fluids predict their divergence as the limit of hard sphere\n(HS) interaction is approached. However, elastic moduli of a true HS fluid are\nfinite. Here we demonstrate that this paradox reveals the soft- to hard-sphere\ncrossover in fluid excitations and thermodynamics. With extensive\n\\emph{in-silico} study of fluids with repulsive power-law interactions\n($\\propto r^{-n}$), we locate the crossover at $n\\simeq 10-20$ and develop a\nsimple and accurate model for the HS regime. The results open novel prospects\nto deal with the elasticity and related phenomena in various systems, from\nsimple fluids to melts and glasses."
    },
    {
        "anchor": "Testing quantum correlations in a confined atomic cloud by scattering\n  fast atoms: Direct and time reversed processes: We suggest measuring the one-particle density matrix of a trapped ultracold\natomic cloud by scattering fast atoms in a pure momentum state off the cloud.\nThe lowest-order probability for the process, resulting in a pair of outcoming\nfast atoms for each incoming one, as well as of its time reversed counterpart,\nturns out to be given by the Fourier transform of the density matrix.\nAccordingly, important information about quantum correlations can be deduced\ndirectly from the differential scattering cross-section of these processes.\nSeveral most interesting cases of scattering - from a single condensate\ncontaining a vortex, and from a split condensate characterized by some phase\ndifference - are discussed.",
        "positive": "Static and dynamic response of a fluid-fluid interface to electric point\n  and line charge: We consider the behaviour of a dielectric fluid-fluid interface in the\npresence of a strong electric field from a point charge and line charge,\nrespectively, both statically and, in the latter case, dynamically. The fluid\nsurface is elevated above its undisturbed level until balance is reached\nbetween the electromagnetic lifting force, gravity and surface tension. We\nderive ordinary differential equations for the shape of the fluid-fluid\ninterface which are solved numerically with standard means, demonstrating how\nthe elevation depends on field strength and surface tension coefficient. In the\ndynamic case of a moving line charge, the surface of an inviscid liquid-liquid\ninterface is left to oscillate behind the moving charge after it has been\nlifted against the force of gravity. We show how the wavelength of the\noscillations depends on the relative strength of the forces of gravity and\ninertia, whereas the amplitude of the oscillations is a nontrivial function of\nthe velocity at which the line charge moves."
    },
    {
        "anchor": "A minimal model for acoustic forces on Brownian particles: We present a generalization of the inertial coupling (IC) [Usabiaga et al. J.\nComp. Phys. 2013] which permits the resolution of radiation forces on small\nparticles with arbitrary acoustic contrast factor. The IC method is based on a\nEulerian-Lagrangian approach: particles move in continuum space while the fluid\nequations are solved in a regular mesh (here we use the finite volume method).\nThermal fluctuations in the fluid stress, important below the micron scale, are\nalso taken into account following the Landau-Lifshitz fluid description. Each\nparticle is described by a minimal cost resolution which consists on a single\nsmall kernel (bell-shaped function) concomitant to the particle. The main role\nof the particle kernel is to interpolate fluid properties and spread particle\nforces. Here, we extend the kernel functionality to allow for an arbitrary\nparticle compressibility. The particle-fluid force is obtained from an imposed\nno-slip constraint which enforces similar particle and kernel fluid velocities.\nThis coupling is instantaneous and permits to capture the fast, non-linear\neffects underlying the radiation forces on particles. Acoustic forces arise\neither because an excess in particle compressibility (monopolar term) or in\nmass (dipolar contribution) over the fluid values. Comparison with theoretical\nexpressions show that the present generalization of the IC method correctly\nreproduces both contributions. Due to its low computational cost, the present\nmethod allows for simulations with many particles using a standard Graphical\nProcessor Unit (GPU).",
        "positive": "Anisotropic Random Networks of Semiflexible Polymers: Motivated by the organization of crosslinked cytoskeletal biopolymers, we\npresent a semimicroscopic replica field theory for the formation of anisotropic\nrandom networks of semiflexible polymers. The networks are formed by\nintroducing random permanent crosslinks which fix the orientations of the\ncorresponding polymer segments to align with one another. Upon increasing the\ncrosslink density, we obtain a continuous gelation transition from a fluid\nphase to a gel where a finite fraction of the system gets localized at random\npositions. For sufficiently stiff polymers, this positional localization is\naccompanied by a {\\em continuous} isotropic-to-nematic (IN) transition occuring\nat the same crosslink density. As the polymer stiffness decreases, the IN\ntransition becomes first order, shifts to a higher crosslink density, and is\npreceeded by an orientational glass (statistically isotropic amorphous solid)\nwhere the average polymer orientations freeze in random directions."
    },
    {
        "anchor": "Density-functional theory for fermions in the unitary regime: In the unitary regime, fermions interact strongly via two-body potentials\nthat exhibit a zero range and a (negative) infinite scattering length. The\nenergy density is proportional to the free Fermi gas with a proportionality\nconstant $\\xi$. We use a simple density functional parametrized by an effective\nmass and the universal constant $\\xi$, and employ Kohn-Sham density-functional\ntheory to obtain the parameters from fit to one exactly solvable two-body\nproblem. This yields $\\xi=0.42$ and a rather large effective mass. Our approach\nis checked by similar Kohn-Sham calculations for the exactly solvable Calogero\nmodel.",
        "positive": "How crosslink numbers shape the large-scale physics of cytoskeletal\n  materials: Cytoskeletal networks are the main actuators of cellular mechanics, and a\nfoundational example for active matter physics. In cytoskeletal networks,\nmotion is generated on small scales by filaments that push and pull on each\nother via molecular-scale motors. These local actuations give rise to large\nscale stresses and motion. To understand how microscopic processes can give\nrise to self-organized behavior on larger scales it is important to consider\nwhat mechanisms mediate long-ranged mechanical interactions in the systems. Two\nscenarios have been considered in the recent literature. The first are systems\nwhich are relatively sparse, in which most of the large scale momentum transfer\nis mediated by the solvent in which cytoskeletal filaments are suspended. The\nsecond, are systems in which filaments are coupled via crosslink molecules\nthroughout. Here, we review the differences and commonalities between the\nphysics of these two regimes. We also survey the literature for the numbers\nthat allow us to place a material within either of these two classes."
    },
    {
        "anchor": "Dynamics of evaporative colloidal patterning: Drying suspensions often leave behind complex patterns of particulates, as\nmight be seen in the coffee stains on a table. Here we consider the dynamics of\nperiodic band or uniform solid film formation on a vertical plate suspended\npartially in a drying colloidal solution. Direct observations allow us to\nvisualize the dynamics of the band and film deposition, and the transition in\nbetween when the colloidal concentration is varied. A minimal theory of the\nliquid meniscus motion along the plate reveals the dynamics of the banding and\nits transition to the filming as a function of the ratio of deposition and\nevaporation rates. We also provide a complementary multiphase model of colloids\ndissolved in the liquid, which couples the inhomogeneous evaporation at the\nevolving meniscus to the fluid and particulate flows and the transition from a\ndilute suspension to a porous plug. This allows us to determine the\nconcentration dependence of the bandwidth and the deposition rate. Together,\nour findings allow for the control of drying-induced patterning as a function\nof the colloidal concentration and evaporation rate.",
        "positive": "Surface Shape of Two-Dimensional Granular Piles: We study the surface shape of two-dimensional piles using experiments and a\ncontinuum theory for surface flows of granular materials (the BCRE equations).\nWe first obtain an analytical solution to the BCRE equations with a simple\ntransformation and show that the surface shapes thereby predicted are in good\nagreement with the experimental results. By means of such an analytical\nsolution, we find that the formation of the curved tails at the bottom of such\npiles depends not only on the properties of the granular materials but also on\nthe drift velocity of the grains within the rolling layer."
    },
    {
        "anchor": "Ordering properties of anisotropic hard bodies in one-dimensional\n  channels: The phase behavior and structural properties of hard anisotropic particles\n(prisms and dumbbells) are examined in one-dimensional channels using the\nParsons--Lee (PL) theory, and the transfer-matrix and neighbor-distribution\nmethods. The particles are allowed to move freely along the channel, while\ntheir orientations are constrained such that one particle can occupy only two\nor three different lengths along the channel. In this confinement setting, hard\nprisms behave as an additive mixture, while hard dumbbells behave as a\nnon-additive one. We prove that all methods provide exact results for the phase\nproperties of hard prisms, while only the neighbor-distribution and\ntransfer-matrix methods are exact for hard dumbbells. This shows that\nnon-additive effects are incorrectly included into the PL theory, which is a\nsuccessful theory of the isotropic-nematic phase transition of rod-like\nparticles in higher dimensions. In the one-dimensional channel, the\norientational ordering develops continuously with increasing density, i.e., the\nsystem is isotropic only at zero density, while it becomes perfectly ordered at\nthe close-packing density. We show that there is no orientational correlation\nin the hard prism system, while the hard dumbbells are orientationally\ncorrelated with diverging correlation length at close packing. On the other\nhand, positional correlations are present for all the systems, the associated\ncorrelation length diverging at close packing.",
        "positive": "Constant-force approach to discontinuous potentials: Aiming to approach the thermodynamical properties of hard-core systems by\nstandard molecular dynamics simulation, we propose setting a repulsive\nconstant-force for overlapping particles. That is, the discontinuity of the\npair potential is replaced by a linear function with a large negative slope.\nHence, the core-core repulsion, usually modeled with a power function of\ndistance, yields a large force as soon as the cores slightly overlap. This\nleads to a quasi-hardcore behavior. The idea is tested for a triangle potential\nof short range. The results obtained by replica exchange molecular dynamics for\nseveral repulsive forces are contrasted with the ones obtained for the\ndiscontinuous potential and by means of replica exchange Monte Carlo. We found\nremarkable agreements for the vapor-liquid coexistence densities as well as for\nthe surface tension."
    },
    {
        "anchor": "Clogging and Jamming of Colloidal Monolayers Driven Across a Disordered\n  Landscape: We experimentally investigate the clogging and jamming of interacting\nparamagnetic colloids driven through a quenched disordered landscape of fixed\nobstacles. When the particles are forced to cross a single aperture between two\nobstacles, we find an intermittent dynamics characterized by an exponential\ndistribution of burst size. At the collective level, we observe that quenched\ndisorder decreases the particle ow, but it also greatly enhances the \"faster is\nslower\" effect, that occurs when increasing the particle speed. Further, we\nshow that clogging events may be controlled by tuning the pair interactions\nbetween the particles during transport, such that the colloidal ow decreases\nfor repulsive interactions, but increases for anisotropic attraction. We\nprovide an experimental test-bed to investigate the crucial role of disorder on\nclogging and jamming in driven microscale matter.",
        "positive": "Feasibility of single-order parameter description of equilibrium viscous\n  liquid dynamics: Molecular dynamics results for the dynamic Prigogine-Defay ratio are\npresented for two glass-forming liquids, thus evaluating the experimentally\nrelevant quantity for testing whether metastable-equilibrium liquid dynamics to\na good approximation are described by a single parameter. For the Kob-Andersen\nbinary Lennard-Jones mixture as well as for an asymmetric dumbbell model liquid\na single-parameter description works quite well. This is confirmed by\ntime-domain results where it is found that energy and pressure fluctuations are\nstrongly correlated on the alpha-time scale in the NVT ensemble; in the NpT\nensemble energy and volume fluctuations similarly correlate strongly."
    },
    {
        "anchor": "Positive and Negative Drag, Dynamic Phases, and Commensurability in\n  Coupled One-Dimensional Channels of Particles with Yukawa Interactions: We introduce a simple model consisting of two or three coupled\none-dimensional channels of particles with Yukawa interactions. For the two\nchannel system, when an external drive is applied only to the top or primary\nchannel, we find a transition from locked flow where particles in both channels\nmove together to decoupled flow where the particles in the secondary or\nundriven channel move at a slower velocity than the particles in the primary or\ndriven channel. Pronounced commensurability effects in the decoupling\ntransition occur when the ratio of the number of particles in the top and\nbottom channels is varied, and the coupling of the two channels is enhanced\nwhen this ratio is an integer or a rational fraction. Near the commensurate\nfillings, we find additional features in the velocity-force curves caused by\nthe slipping of individual vacancies or incommensurations in the secondary\nchannels. For three coupled channels, when only the top channel is driven we\nfind a remarkably rich variety of distinct dynamic phases, including multiple\ndecoupling and recoupling transitions. These transitions produce pronounced\nsignatures in the velocity response of each channel. We also find regimes where\na negative drag effect can be induced in one of the non-driven channels. The\nparticles in this channel move in the opposite direction from the particles in\nthe driven channel due to the mixing of the two different periodic frequencies\nproduced by the discrete motion of the particles in the two other channels. In\nthe two channel system, we also demonstrate a ratchet effect for the particles\nin the secondary channel when an asymmetric drive is applied to the primary\nchannel. This ratchet effect is similar to that observed in superconducting\nvortex systems when there is a coupling between two different species of\nvortices.",
        "positive": "Local rules for fabricating allosteric networks: Mechanical properties of disordered networks can be significantly tailored by\nmodifying a small fraction of their bonds. This procedure has been used to\ndesign and build mechanical metamaterials with a variety of responses. A\nlong-range 'allosteric' response, where a localized input strain at one site\ngives rise to a localized output strain at a distant site, has been of\nparticular interest. This work presents a novel approach to incorporating\nallosteric responses in experimental systems by pruning disordered networks\n$\\textit{in-situ}$. Previous work has relied on computer simulations to design\nand predict the response of such systems using a cost function where the\nresponse of the entire network to each bond removal is used at each step to\ndetermine which bond to prune. It is not feasible to follow such a design\nprotocol in experiments where one has access only to local response at each\nsite. This paper presents design algorithms that allow determination of what\nbonds to prune based purely on the local stresses in the network without\nemploying a cost function; using only local information, allosteric networks\nare designed in simulations and then built out of real materials. The results\nshow that some pruning strategies work better than others when translated into\nan experimental system. A method is presented to measure local stresses\nexperimentally in disordered networks. This approach is then used to implement\npruning methods to design desired responses $\\textit{in-situ}$. Results from\nthese experiments confirm that the pruning methods are robust and work in a\nreal laboratory material."
    },
    {
        "anchor": "Plastic Instabilities in Charged Granular Systems: Competition between\n  Elasticity and Electrostatics: Electrostatic theory preserves charges, but allows dipolar excitations.\nElasticity theory preserves dipoles, but allows quadrupolar (Eshelby like)\nplastic events. Charged amorphous granular systems are interesting in their own\nright; here we focus on their plastic instabilities and examine their\nmechanical response to external strain and to external electric field, to\nexpose the competition between elasticity and electrostatics. In this paper a\ngeneric model is offered, its mechanical instabilities are examined and a\ntheoretical analysis is presented. Plastic instabilities are discussed as\nsaddle-node bifurcations that can be fully understood in terms of eigenvalues\nand eigenfunctions of the relevant Hessian matrix. This system exhibits moduli\nthat describe how electric polarization and stress are influenced by strain and\nelectric field. Theoretical expression for these moduli are offered and\ncompared to the measurements in numerical simulations.",
        "positive": "Elastic free-energy of wormlike micellar chains: theory and suggested\n  experiments: The extensive application of surfactants motivates comprehensive and\npredictive theoretical studies that improve our understanding of the behaviour\nof these complex systems. In this study, an expression for the elastic\nfree-energy density of a wormlike micellar chain is derived taking into account\ninteractions between its constituent molecules. The resulting expression\nincorporates the sum of a quadratic term in the curvature and a quadratic term\nin the torsion of the centerline of wormlike micelle and thus resembles\nfree-energy density functions for polymer chains and DNA available in the\nliterature. The derived model is applied on a wormlike micelle in the shape of\na circular arc, open or closed. A detailed application of the derived model on\nwormlike micelles of toroidal shape, along with employing necessary\nstatistical-thermodynamical concepts of self-assembly, is performed, and the\nresults are found to be consistent with the ones available in the literature.\nSteps towards obtaining the material parameters through experiments are\nsuggested and discussed."
    },
    {
        "anchor": "Effect of Confinement and Topology: 2-TIPS vs MIPS: 2-TIPS (Two Temperature induced phase separation) refers to the phase\nseparation phenomenon observed in mixtures of active and passive particles\nwhich are modelled using scalar activity. The active particles are connected to\na thermostat at high temperature while the passive particles are connected to\nthe thermostat at low temperature and the relative temperature difference\nbetween \"hot\" and \"cold\" particles is taken as the measure of the activity of\nthe non-equilibrium system. The study of such binary mixtures of hot and cold\nparticles under various kinds of confinement is an important problem in many\nphysical and biological processes. The nature and extent of phase separation\nare heavily influenced by the geometry of confinement, activity, and density of\nthe non-equilibrium binary mixture. Investigating such 3D binary mixtures\nconfined by parallel walls, we observe that, the active and passive particles\nphase separate, but the extent of phase separation is reduced compared to bulk\nphase separation at high densities and enhanced at low densities. However, when\nthe binary mixture of active and passive particles is confined inside a\nspherical cavity, the phase separation is radial for small radii of the\nconfining sphere and the extent of phase separation is higher compared to their\nbulk counterparts. Confinement leads to interesting properties in the\npassive(cold) region like enhanced layering and high compression in the\ndirection parallel to the confining wall. In 2D, both the bulk and confined\nsystems of the binary mixture show a significant decrement in the extent of\nphase separation at higher densities. This observation is attributed to the\ntrapping of active particles inside the passive cluster, which increases with\ndensity. similar phase co-existence.",
        "positive": "Mean-field theory of the Interaction of the Magnesium Ion with\n  Biopolymers: The Case of Lysozyme: A statistical theory is presented of the magnesium ion interacting with\nlysozyme under conditions where the latter is positively charged. Temporarily\nassuming magnesium is not noncovalently bound to the protein, I solve the\nnonlinear Poisson-Boltzmann equation accurately and uniformly in a perturbative\nfashion. The resulting expression for the effective charge, which is larger\nthan nominal owing to overshooting, is subtle and cannot be asymptotically\nexpanded at high ionic strengths that are practical. An adhesive potential\ntaken from earlier work together with the assumption of possibly bound\nmagnesium is then fitted to be in accord with measurements of the second virial\ncoefficient by Tessier et al. The resulting numbers of bound magnesium ions as\na function of MgBr2 concentration are entirely reasonable compared with\ndensitometry measurements."
    },
    {
        "anchor": "Enhanced diffusion by reciprocal swimming: Purcell's scallop theorem states that swimmers deforming their shapes in a\ntime-reversible manner (\"reciprocal\" motion) cannot swim. Using numerical\nsimulations and theoretical calculations we show here that in a fluctuating\nenvironment, reciprocal swimmers undergo, on time scales larger than that of\ntheir rotational diffusion, diffusive dynamics with enhanced diffusivities,\npossibly by orders of magnitude, above normal translational diffusion.\nReciprocal actuation does therefore lead to a significant advantage over\nnon-motile behavior for small organisms such as marine bacteria.",
        "positive": "Colloids in Cholesterics: Size-Dependent Defects and Non-Stokesian\n  Microrheology: We simulate a colloidal particle (radius R) in a cholesteric liquid crystal\n(pitch p) with tangential order parameter alignment at the particle surface.\nThe local defect structure evolves from a dipolar pair of surface defects\n(boojums) at small R/p to a pair of twisted disclination lines wrapping around\nthe particle at larger values. On dragging the colloid with small velocity v\nthrough the medium along the cholesteric helix axis (an active microrheology\nmeasurement), we find a hydrodynamic drag force that scales linearly with v but\nsuperlinearly with R-in striking violation of Stokes' law, as generally used to\ninterpret such measurements."
    },
    {
        "anchor": "Knots in Macromolecules in Constraint Space: We find a power law for the number of knot-monomers with an exponent $0.39\n\\pm0.13$ in agreement with previous simulations. For the average size of a knot\nwe also obtain a power law $N_m=2.56\\cdot N^{0.20\\pm0.04}$. We further present\ndata on the average number of knots given a certain chain length and confirm a\npower law behaviour for the number of knot-monomers. Furthermore we study the\naverage crossing number for random and self-avoiding walks as well as for a\nmodel polymer with and without geometric constraints. The data confirms the\n$aN\\log N + bN$ law in the case of without excluded volume and determines the\nconstants $a$ and $b$ for various cases. For chains with excluded volume the\ndata for chains up to N=1500 is consistent with $aN\\log N + bN$ rather than the\nproposed $N^{4/3}$ law. Nevertheless our fits show that the $N^{4/3}$ law is a\nsuitable approximation.",
        "positive": "Exact Criterion for Determining Clustering vs. Reentrant Melting\n  Behavior for Bounded Interaction Potentials: We examine in full generality the phase behavior of systems whose constituent\nparticles interact by means of potentials which do not diverge at the origin,\nare free of attractive parts and decay fast enough to zero as the interparticle\nseparation r goes to infinity. By employing a mean field-density functional\ntheory which is shown to become exact at high temperatures and/or densities, we\nestablish a criterion which determines whether a given system will freeze at\nall temperatures or it will display reentrant melting and an upper freezing\ntemperature."
    },
    {
        "anchor": "Ring to Mountain Transition in Deposition Pattern of Drying: When a droplet containing a non-volatile component is dried on a substrate,\nit leaves a ringlike deposit on the substrate. We propose a theory which\npredicts the deposit distribution based on a model of fluid flow and contact\nline motion of the droplet. It is shown that the deposition pattern changes\ncontinuously from coffee-ring to volcano-like and to mountain-like depending on\nthe mobility of the contact line and the evaporation rate. Analytical\nexpression is given for the peak position of the distribution of deposit left\non the substrate.",
        "positive": "Long time behavior of non-autonomous Fokker-Planck equations and the\n  cooling of granular gases: We analyze the asymptotic behavior of linear Fokker-Planck equations with\ntime-dependent coefficients. Relaxation towards a Maxwellian distribution with\ntime-dependent temperature is shown under explicitly computable conditions. We\napply this result to the study of Brownian motion in granular gases as\nintroduced J. J. Brey, J. Dufty and A. Santos (1999), by showing that the\nHomogenous Cooling State attracts any solution at an algebraic rate."
    },
    {
        "anchor": "Phase Transitions in Hardcore Lattice Gases on the Honeycomb Lattice: We study lattice gas systems on the honeycomb lattice where particles exclude\nneighboring sites up to order $k$ ($k=1\\ldots5$) from being occupied by another\nparticle. Monte Carlo simulations were used to obtain phase diagrams and\ncharacterize phase transitions as the system orders at high packing fractions.\nFor systems with first neighbors exclusion (1NN), we confirm previous results\nsuggesting a continuous transition in the 2D-Ising universality class.\nExclusion up to second neighbors (2NN) lead the system to a two-step melting\nprocess where, first, a high density columnar phase undergoes a first order\nphase transition with non-standard scaling to a solid-like phase with short\nrange ordered domains and, then, to fluid-like configurations with no sign of a\nsecond phase transition. 3NN exclusion, surprisingly, shows no phase transition\nto an ordered phase as density is increased, staying disordered even to packing\nfractions up to 0.98. The 4NN model undergoes a continuous phase transition\nwith critical exponents close to the 3-state Potts model. The 5NN system\nundergoes two first order phase transitions, both with non-standard scaling.\nWe, also, propose a conjecture concerning the possibility of more than one\nphase transition for systems with exclusion regions further than 5NN based on\ngeometrical aspects of symmetries.",
        "positive": "High-temperature superfluidity of fermionic atoms in optical lattices: The experimental realizations of degenerate Bose and Fermi atomic samples\nhave stimulated a new wave of studies of quantum many-body systems in the\ndilute and weakly interacting regime. The intriguing prospective of extending\nthese studies into the domain of strongly correlated phenomena is hindered by\nthe apparent relative weakness of atomic interactions. The effects due to\ninteractions can, however, be enhanced if the atoms are confined in optical\npotentials created by standing light waves. The present letter shows that these\ntechniques, when applied to ensembles of cold fermionic atoms, can be used to\ndramatically increase the transition temperature to a superfluid state and thus\nmake it readily observable under current experimental conditions. Depending\nupon carefully controlled parameters, a transition to a superfluid state of\nCooper pairs, antiferromagnetic states or more exotic d-wave pairing states can\nbe induced and probed. The results of proposed experiments can provide a\ncritical insight into the origin of high-temperature superconductivity in\ncuprates."
    },
    {
        "anchor": "Lattice-Boltzmann Method for Non-Newtonian Fluid Flows: We study an ad hoc extension of the Lattice-Boltzmann method that allows the\nsimulation of non-Newtonian fluids described by generalized Newtonian models.\nWe extensively test the accuracy of the method for the case of shear-thinning\nand shear-thickening truncated power-law fluids in the parallel plate geometry,\nand show that the relative error compared to analytical solutions decays\napproximately linear with the lattice resolution. Finally, we also tested the\nmethod in the reentrant-flow geometry, in which the shear-rate is no-longer a\nscalar and the presence of two singular points requires high accuracy in order\nto obtain satisfactory resolution in the local stress near these points. In\nthis geometry, we also found excellent agreement with the solutions obtained by\nstandard finite-element methods, and the agreement improves with higher lattice\nresolution.",
        "positive": "Mechanical and Vibrational Properties of Three-Dimensional Dimer\n  Packings Near the Jamming Transition: We comprehensively study mechanical and vibrational properties of dimer\npackings in three-dimensional space with particular attention on critical\nscaling behaviors near the jamming transition. First, we confirm the dependence\nof the packing fraction at the transition on the aspect ratio, the isostatic\ncontact number at the transition, and the scaling dependence of the excess\ncontact number on the excess density. Second, we study the elastic moduli, bulk\nand shear moduli, and establish power-law scaling of them. Finally, we study\nthe vibrational density of states and its characteristic frequency. The\nvibrational density of states shows two plateaus in the lower- and\nhigher-frequency regions, which are characterized by rotational and\ntranslational vibrational modes, respectively. The onset frequency of the\nlower-frequency plateau scales linearly to the square root of excess density.\nThe scaling laws in the mechanical and vibrational properties are consistent\nbetween two- and three-dimensional dimers, and they are identical to those in\nspheres."
    },
    {
        "anchor": "Effective squirmer models for self-phoretic chemically active spherical\n  colloids: Various aspects of self-motility of chemically active colloids in Newtonian\nfluids can be captured by simple models for their chemical activity plus a\nphoretic slip hydrodynamic boundary condition on their surface. For particles\nof simple shapes (e.g., spheres) -- as employed in many experimental studies --\nwhich move at very low Reynolds numbers in an unbounded fluid, such models of\nchemically active particles effectively map onto the well studied so-called\nhydrodynamic squirmers [S. Michelin and E. Lauga, J. Fluid Mech. \\textbf{747},\n572 (2014)]. Accordingly, intuitively appealing analogies of\n\"pusher/puller/neutral\" squirmers arise naturally. Within the framework of\nself-diffusiophoresis we illustrate the above mentioned mapping and the\ncorresponding flows in an unbounded fluid for a number of choices of the\nactivity function (i.e., the spatial distribution and the type of chemical\nreactions across the surface of the particle). We use the central collision of\ntwo active particles as a simple, paradigmatic case for demonstrating that in\nthe presence of other particles or boundaries the behavior of chemically active\ncolloids may be \\textit{qualitatively} different, even in the far field, from\nthe one exhibited by the corresponding \"effective squirmer\", obtained from the\nmapping in an unbounded fluid. This emphasizes that understanding the\ncollective behavior and the dynamics under geometrical confinement of\nchemically active particles necessarily requires to explicitly account for the\ndependence of the hydrodynamic interactions on the distribution of chemical\nspecies resulting from the activity of the particles.",
        "positive": "Larmor Frequency Depends on Structural Anisotropy in Magnetically\n  Heterogeneous Media: Purpose: To investigate the effect of anisotropic magnetic microstructure on\nthe measurable Larmor frequency offset in media with heterogeneous magnetic\nsusceptibility. Specific objectives were (i) validation of recently developed\ntheory for the case of fast diffusion and (ii) investigation of the transition\nbetween the regimes of fast and slow diffusion. Methods: Monte Carlo\nsimulations in synthetic media. Results: Simulations demonstrate a perfect\nagreement with the previously developed theory for fast diffusion. Beyond this\nregime, the frequency offset shows a pronounced dependence on the medium\nmicroarchitecture and the diffusivity of NMR-reporting spins in relation to the\nmagnitude of the susceptibility-induced magnetic field. Conclusion: While the\neffect of myelin in brain white matter is commonly treated assuming efficient\ndiffusion narrowing, this regime does not hold for larger cells or higher\nmagnetic susceptibility. In such a case, the effect essentially deviates from\nthe prediction based on the assumption of diffusion narrowing."
    },
    {
        "anchor": "Densest vs. jammed packings of 2D bent-core trimers: We identify the maximally dense lattice packings of tangent-disk trimers with\nfixed bond angles ($\\theta = \\theta_0$) and contrast them to both their\nnonmaximally-dense-but-strictly-jammed lattice packings as well as the\ndisordered jammed states they form for a range of compression protocols. While\nonly $\\theta_0 = 0,\\ 60^\\circ,\\ \\rm{and}\\ 120^\\circ$ trimers can form the\ntriangular lattice, maximally-dense maximally-symmetric packings for all\n$\\theta_0$ fall into just two categories distinguished by their bond\ntopologies: half-elongated-triangular for $0 < \\theta_0 < 60^\\circ$ and\nelongated-snub-square for $60^\\circ < \\theta_0 < 120^\\circ$. The presence of\ndegenerate, lower-symmetry versions of these densest packings combined with\nseveral families of less-dense-but-strictly-jammed lattice packings act in\nconcert to promote jamming.",
        "positive": "The microscopic origins of stretched exponential relaxation in two model\n  glass-forming liquids as probed by simulations in the isoconfigurational\n  ensemble: The origin of stretched exponential relaxation in supercooled glass-forming\nliquids is one of the central questions regarding the anomalous dynamics of\nthese fluids. The dominant explanation for this phenomenon has long been the\nproposition that spatial averaging over a heterogeneous distribution of locally\nexponential relaxation processes leads to stretching. Here we perform\nsimulations of model polymeric and small-molecule glass-formers in the\nisoconfigurational ensemble to show that stretching instead emerges from a\ncombination of spatial averaging and locally nonexponential relaxation. Results\nindicate that localities in the fluid exhibiting faster-than-average relaxation\ntend to exhibit locally stretched relaxation, whereas slower-than-average\nrelaxing domains exhibit compressed exponential relaxation. We show that local\nstretching is predicted by loose local caging, as measured by the Debye-Waller\nfactor, and vice versa. This phenomenology in the local relaxation of\nin-equilibrium glasses parallels the dynamics of out of equilibrium under-dense\nand over-dense glasses, which likewise exhibit an asymmetry in their degree of\nstretching vs compression. On the basis of these results, we hypothesize that\nlocal stretching and compression in equilibrium glass-forming liquids results\nfrom evolution of particle mobilities over a single local relaxation time, with\nslower particles tending towards acceleration and vice versa. In addition to\nproviding new insight into the origins of stretched relaxation, these results\nhave implications for the interpretation of stretching exponents as measured\nvia metrologies such as dielectric spectroscopy: measured stretching exponents\ncannot universally be interpreted as a direct measure of the breadth of an\nunderlying distribution of relaxation times."
    },
    {
        "anchor": "On the theory of Double Quantum NMR in polymer systems: the second\n  cumulant approximation for many spin I=1/2 systems: General analytical expressions for Double Quantum Nuclear Magnetic Resonance\n(NMR) kinetic curves of many-spin I=1/2 systems are derived with an accuracy of\nthe second cumulant approximation. The expressions obtained exactly describe\nthe initial part of the kinetic curves and provide a reasonable approximation\nup to times of about twice the effective spin-relaxation time. For the case\nwhen the system contains two isolated spins, this result exactly reproduces\nknown expressions. In the case of polymer melts, the intermolecular magnetic\ndipole-dipole interactions significantly influence the time dependence of the\nDQ NMR kinetic curves.",
        "positive": "Effect of Director Distortions on Polymer-Liquid Crystal Phase\n  Separation: We study photopolymerization in a low-molecular weight liquid crystal with\nnon-uniform director gradients. Phase separation results in spatially\nnon-uniform distribution of polymer density controlled by the distorted nematic\nmatrix. Director-gradient-controlled polymerization provides a new and useful\ntechnique to assemble micron-scale polymer architectures."
    },
    {
        "anchor": "Dynamics of Chainlike Molecules on Surfaces: We consider the diffusion and spreading of chainlike molecules on solid\nsurfaces. We first show that the steep spherical cap shape density profiles,\nobserved in some submonolayer experiments on spreading polymer films, imply\nthat the collective diffusion coefficient $D_C(\\theta)$ must be an increasing\nfunction of the surface coverage $\\theta$ for small and intermediate coverages.\nThrough simulations of a discrete model of interacting chainlike molecules, we\ndemonstrate that this is caused by an entropy-induced repulsive interaction.\nExcellent agreement is found between experimental and numerically obtained\ndensity profiles in this case, demonstrating that steep submonolayer film edges\nnaturally arise due to the diffusive properties of chainlike molecules. When\nthe entropic repulsion dominates over interchain attractions, $D_C(\\theta)$\nfirst increases as a function of $\\theta$ but then eventually approaches zero\nfor $\\theta \\to 1$. The maximum value of $D_C(\\theta)$ decreases for increasing\nattractive interactions, leading to density profiles that are in between\nspherical cap and Gaussian shapes. We also develop an analytic mean field\napproach to explain the diffusive behavior of chainlike molecules. The\nthermodynamic factor in $D_C(\\theta)$ is evaluated using effective free energy\narguments, and the chain mobility is calculated numerically using the recently\ndeveloped dynamic mean field theory. Good agreement is obtained between theory\nand simulations.",
        "positive": "Inertial effects in the Saffman-Taylor instability: For the Saffman-Taylor instability, the inertia of the fluid may become\nimportant for large Reynolds numbers Re. We investigate the effects of inertia\non the width of the viscous fingers experimentally. We find that, due to\ninertia, the finger width can increase with increasing speed, contrary to what\nhappens at small Re. We find that inertial effects need to be considered above\na critical Weber number We. In this case it can be shown that the finger width\nis governed by a balance between viscous forces and inertia. This allows us to\ndefine a modified control parameter 1/B', which takes the corrections due to\ninertia into account; rescaling the experimental data with 1/B', they all\ncollapse onto the universal curve for the classical Saffman-Taylor instability.\nSubsequently, we try and rationalize our observations. Numerical simulations\ntaking into account a modification of Darcy law to include inertia, are found\nto only qualitatively reproduce the experimental findings, pointing to the\nimportance of three-dimensional effects."
    },
    {
        "anchor": "Criteria for shear banding in time-dependent flows of complex fluids: Within a highly generalised theoretical framework for the flow properties of\ncomplex fluids, we study the onset of shear banding in the three most common\ntime-dependent experimental protocols: step stress, step strain and shear\nstartup. By means of a linear stability analysis we derive a fluid-universal\ncriterion for the onset of banding, separately for each protocol, that depends\nonly on the shape of the experimentally measured time-dependent rheological\nresponse function, independent of the constitutive law and internal state\nvariables of the particular fluid in question. Our predictions thus have the\nsame status, in these time-dependent flows, as the widely known criterion for\nbanding in steady state (of negatively sloping shear stress vs. shear rate). We\nsupport them with simulations of the rolie-poly model of polymeric fluids, the\nsoft glassy rheology model, and a fluidity model.",
        "positive": "Cracking Condition of Cohesionless Porous Materials in Drying Processes: The invasion of air into porous systems in drying processes is often\nlocalized in soft materials, such as colloidal suspensions and granular pastes,\nand it typically develops in the form of cracks before ordinary drying begins.\nTo investigate such processes, we construct an invasion percolation model on a\ndeformable lattice for cohesionless elastic systems, and with this model we\nderive the condition under which cracking occurs. A Griffith-like condition\ncharacterized by a dimensionless parameter is proposed, and its validity is\nchecked numerically. This condition indicates that the ease with which cracking\noccurs increases as the particles composing the material become smaller, as the\nrigidity of the system increases, and as the degree of heterogeneity\ncharacterizing the drying processes decreases."
    },
    {
        "anchor": "High-order Harmonic Generation in Thermotropic Liquid Crystals: Thermotropic liquid crystals are versatile optical materials that exhibit a\nstate of matter intermediate between liquids and solids. Their properties can\nchange significantly with temperature, pressure, or other external factors,\nleading to different phases. The transport properties within these materials in\ndifferent phases are still largely unexplored and their understanding would\nenable exciting prospects for innovative technological advancements. High-order\nharmonic spectroscopy proved to be a powerful spectroscopic tool for\ninvestigating the electronic and nuclear dynamics in matter. Here we report the\nfirst experimental observation of high-order harmonic generation in\nthermotropic liquid crystals in two different phase states, nematic and\nisotropic. We found the harmonic emission in the nematic phase to be strongly\ndependent on the relative orientation of the driving field polarization with\nrespect to the liquid crystal alignment. Specifically, the harmonic yield has a\nmaximum when the molecules are aligned perpendicularly to the polarization of\nthe incoming radiation. Our results establish the first step for applying\nhigh-order harmonic spectroscopy as a tool for resolving ultrafast electron\ndynamics in liquid crystals with unprecedented temporal and spatial resolution.",
        "positive": "Statistical Mechanics of Semiflexible Polymers: Theory and Experiment: We review the physical properties of macromolecular networks, consisting of\nsemiflexible polymers such as actin. We start by giving a theoretical analysis\nof the conformational statistics and mechanical response of single filaments.\nExperimentally relevant quantities such as the end-to-end distribution function\nand the force-extension relation are discussed. The results are used to analyze\nthe elastic modulus of an entangled solution of such objects. We also discuss\nthe short time and long time (terminal regime) dynamics and compare our results\nwith recent dynamic light scattering and viscoelastic measurements.\nFurthermore, we analyze the elasticity transition in stochastic models of\ncrosslinked networks."
    },
    {
        "anchor": "Partitioning of energy in highly polydisperse granular gases: A highly polydisperse granular gas is modeled by a continuous distribution of\nparticle sizes, a, giving rise to a corresponding continuous temperature\nprofile, T(a), which we compute approximately, generalizing previous results\nfor binary or multicomponent mixtures. If the system is driven, it evolves\ntowards a stationary temperature profile, which is discussed for several\ndriving mechanisms in dependence on the variance of the size distribution. For\na uniform distribution of sizes, the stationary temperature profile is\nnonuniform with either hot small particles (constant force driving) or hot\nlarge particles (constant velocity or constant energy driving). Polydispersity\nalways gives rise to non-Gaussian velocity distributions. Depending on the\ndriving mechanism the tails can be either overpopulated or underpopulated as\ncompared to the molecular gas. The deviations are mainly due to small\nparticles. In the case of free cooling the decay rate depends continuously on\nparticle size, while all partial temperatures decay according to Haff's law.\nThe analytical results are supported by event driven simulations for a large,\nbut discrete number of species.",
        "positive": "Flow rule, self-channelization and levees in unconfined granular flows: Unconfined granular flows along an inclined plane are investigated\nexperimentally. During a long transient, the flow gets confined by quasistatic\nbanks but still spreads laterally towards a well-defined asymptotic state\nfollowing a nontrivial process. Far enough from the banks a scaling for the\ndepth averaged velocity is obtained, which extends the one obtained for\nhomogeneous steady flows. Close to jamming it exhibits a crossover towards a\nnonlocal rheology. We show that the levees, commonly observed along the sides\nof the deposit upon interruption of the flow, disappear for long flow\ndurations. We demonstrate that the morphology of the deposit builds up during\nthe flow, in the form of an underlying static layer, which can be deduced from\nsurface velocity profiles, by imposing the same flow rule everywhere in the\nflow."
    },
    {
        "anchor": "Power functional theory for Brownian dynamics: Classical density functional theory (DFT) provides an exact variational\nframework for determining the equilibrium properties of inhomogeneous fluids.\nWe report a generalization of DFT to treat the non-equilibrium dynamics of\nclassical many-body systems subject to Brownian dynamics. Our approach is based\nupon a dynamical functional consisting of reversible free energy changes and\nirreversible power dissipation. Minimization of this `free power' functional\nwith respect to the microscopic one-body current yields a closed equation of\nmotion. In the equililibrium limit the theory recovers the standard variational\nprinciple of DFT. The adiabatic dynamical density functional theory is obtained\nwhen approximating the power dissipation functional by that of an ideal gas.\nApproximations to the excess (over ideal) power dissipation yield numerically\ntractable equations of motion beyond the adiabatic approximation, opening the\ndoor to the systematic study of systems far from equilibrium.",
        "positive": "Flow-Switched Bistability in a Colloidal Gel with Non-Brownian Grains: We show that mixing a colloidal gel with larger, non-Brownian grains\ngenerates novel flow-switched bistability. Using a combination of confocal\nmicroscopy and rheology, we find that prolonged moderate shear results in\nliquefaction by collapsing the gel into disjoint globules, whereas fast shear\ngives rise to a yield-stress gel with granular inclusions upon flow cessation.\nWe map out the state diagram of this new `mechanorheological material' with\nvarying granular content and demonstrate that its behavior is also found in\nseparate mixture using different particles and solvents."
    },
    {
        "anchor": "Triple line destabilization -- Tuning film thickness through meniscus\n  curvature: For partially wetting fluids, previous results suggest that the thickness and\nthe dewetting velocity of gravity driven films are uniquely determined by the\ntriple line dynamics. In contrast, when flushing aqueous liquids through\npolymer tubes, our measurements show that the dewetting velocity and thickness\ncan be selected. The control parameter is pressure, i.e. the macroscopic\ncurvature of the meniscus. Our results demonstrate directly the major role\nplayed by the macroscopic geometry in the stability of the triple line in a\ndynamic meniscus as predicted by Eggers (Phys. Rev. Lett. 93, 094502 (2004)).",
        "positive": "Network equilibration and first-principles liquid water: Motivated by the very low diffusivity recently found in ab initio simulations\nof liquid water, we have studied its dependence with temperature, system size,\nand duration of the simulations. We use ab initio molecular dynamics (AIMD),\nfollowing the Born-Oppenheimer forces obtained from density-functional theory\n(DFT). The linear-scaling capability of our method allows the consideration of\nlarger system sizes (up to 128 molecules in this study), even if the main\nemphasis of this work is in the time scale. We obtain diffusivities that are\nsubstantially lower than the experimental values, in agreement with recent\nfindings using similar methods. A fairly good agreement with D(T) experiments\nis obtained if the simulation temperature is scaled down by ~20%. It is still\nan open question whether the deviation is due to the limited accuracy of\npresent density functionals or to quantum fluctuations, but neither technical\napproximations (basis set, localization for linear scaling) nor the system size\n(down to 32 molecules) deteriorate the DFT description in an appreciable way.\nWe find that the need for long equilibration times is consequence of the slow\nprocess of rearranging the H-bond network (at least 20 ps at AIMD's room\ntemperature). The diffusivity is observed to be very directly linked to network\nimperfection. This link does not appear an artefact of the simulations, but a\ngenuine property of liquid water."
    },
    {
        "anchor": "Brownian motion near an elastic cell membrane: A theoretical study: Elastic confinements are an important component of many biological systems\nand dictate the transport properties of suspended particles under flow. In this\nchapter, we review the Brownian motion of a particle moving in the vicinity of\na living cell whose membrane is endowed with a resistance towards shear and\nbending. The analytical calculations proceed through the computation of the\nfrequency-dependent mobility functions and the application of the\nfluctuation-dissipation theorem. Elastic interfaces endow the system with\nmemory effects that lead to a long-lived anomalous subdiffusive regime of\nnearby particles. In the steady limit, the diffusional behavior approaches that\nnear a no-slip hard wall. The analytical predictions are validated and\nsupplemented with boundary-integral simulations.",
        "positive": "Multiple minimum energy paths and scenarios of unwinding transitions in\n  chiral nematic liquid crystals: We apply the minimum energy paths (MEPs) approach to study the helix\nunwinding transition in chiral nematic liquid crystals. A mechanism of the\ntransition is determined by a MEP passing through a first order saddle point on\nthe free energy surface. The energy difference between the saddle point and the\ninitial state gives the energy barrier of the transition. Two starting\napproximations for the paths are used to find the MEPs representing different\ntransition scenarios: (a) the director slippage approximation with in-plane\nhelical structures; and (b) the anchoring breaking approximation that involves\nthe structures with profound out-of-plane director deviations. It is shown\nthat, at sufficiently low voltages, the unwinding transition is solely governed\nby the director slippage mechanism with the planar saddle point structures.\nWhen the applied voltage exceeds its critical value below the threshold of the\nFreedericksz transition, the additional scenario through the anchoring breaking\ntransitions is found to come into play. For these transitions, the saddle point\nstructure is characterized by out-of-plane deformations localized near the\nbounding surface. The energy barriers for different paths of transitions are\ncomputed as a function of the voltage and the anchoring energy strengths."
    },
    {
        "anchor": "A Dynamical Mean Field Theory for the Study of Surface Diffusion\n  Constants: We present a combined analytical and numerical approach based on the Mori\nprojection operator formalism and Monte Carlo simulations to study surface\ndiffusion within the lattice-gas model. In the present theory, the average jump\nrate and the susceptibility factor appearing are evaluated through Monte Carlo\nsimulations, while the memory functions are approximated by the known results\nfor a Langmuir gas model. This leads to a dynamical mean field theory (DMF) for\ncollective diffusion, while approximate correlation effects beyond DMF are\nincluded for tracer diffusion. We apply our formalism to three very different\nstrongly interacting systems and compare the results of the new approach with\nthose of usual Monte Carlo simulations. We find that the combined approach\nworks very well for collective diffusion, whereas for tracer diffusion the\ninfluence of interactions on the memory effects is more prominent.",
        "positive": "The influence of charge and flexibility on smectic phase formation in\n  filamentous virus suspensions: We present experimental measurements of the cholesteric-smectic phase\ntransition of suspensions of charged semiflexible rods as a function of rod\nflexibility and surface charge. The rod particles consist of the bacteriophage\nM13 and closely related mutants, which are structurally identical to this\nvirus, but vary either in contour length and therefore ratio of persistence\nlength to contour length, or vary in surface charge. Surface charge is altered\nin two ways; by changing solution pH and by comparing M13 with {\\it fd} virus,\na mutant which differs from M13 only by the substitution of a single charged\namino acid for a neutral one per viral coat protein. Phase diagrams are\nmeasured as a function of particle length, particle charge and ionic strength.\nThe experimental results are compared with existing theoretical predictions for\nthe phase behavior of flexible rods and charged rods. In contrast to the\nisotropic-cholesteric transition, where theory and experiment agree at high\nionic strength, the nematic-smectic transition exhibits complex charge and\nionic strength dependence significantly different from predicted phase\nbehavior. Possible explanations for these unexpected results are discussed."
    },
    {
        "anchor": "Solution Landscapes of the Simplified Ericksen--Leslie Model and its\n  Comparison with the Reduced Landau--de Gennes Model: We investigate the solution landscapes of a simplified Ericksen--Leslie (sEL)\nvector model for nematic liquid crystals, confined in a two-dimensional square\ndomain with tangent boundary conditions. An efficient numerical algorithm is\ndeveloped to construct the solution landscapes by utilizing the symmetry\nproperties of the model and the domain. Since the sEL model and the reduced\nLandau--de Gennes (rLdG) models can be viewed as Ginzburg--Landau functionals,\nwe systematically compute the solution landscapes of the sEL model, for\ndifferent domain sizes, and compare with the solution landscapes of the\ncorresponding rLdG models. There are many similarities, including the stable\ndiagonal and rotated states, bifurcation behaviors, and sub-solution landscapes\nwith low-index saddle solutions. Significant disparities also exist between the\ntwo models. The sEL vector model exhibits the stable solution $C\\pm$ with\ninterior defects, high-index \"fake defects\" solutions, novel tessellating\nsolutions, and certain types of distinctive dynamical pathways. The solution\nlandscape approach provides a comprehensive and efficient way for model\ncomparison and is applicable to a wide range of mathematical models in physics.",
        "positive": "A variational treatment of material configurations with application to\n  interface motion and microstructural evolution: We present a unified variational treatment of evolving configurations in\ncrystalline solids with microstructure. The crux of our treatment lies in the\nintroduction of a vector configurational field. This field lies in the\nmaterial, or configurational, manifold, in contrast with the traditional\ndisplacement field, which we regard as lying in the spatial manifold. We\nidentify two distinct cases which describe (a) problems in which the\nconfigurational field's evolution is localized to a mathematically sharp\ninterface, and (b) those in which the configurational field's evolution can\nextend throughout the volume. The first case is suitable for describing\nincoherent phase interfaces in polycrystalline solids, and the latter is useful\nfor describing smooth changes in crystal structure and naturally incorporates\ncoherent (diffuse) phase interfaces. For sharp interfaces that are\nout-of-equilibrium, the second law of thermodynamics furnishes restrictions on\nthe kinetic law for the interface velocity. The class of problems in which the\nmaterial undergoes configurational changes between distinct, stable crystal\nstructures are characterized by free energy density functions that are\nnon-convex with respect to configurational strain. For physically meaningful\nsolutions and mathematical well-posedness, it becomes necessary to incorporate\ninterfacial energy. This we have done by introducing a configurational strain\ngradient dependence in the free energy density function following ideas laid\nout by Toupin (Arch. Rat. Mech. Anal. 11, 1962, 385-414). The variational\ntreatment leads to a system of partial differential equations governing the\nconfiguration that is coupled with the traditional equations of nonlinear\nelasticity. Numerical examples are presented to demonstrate interface motion as\nwell as evolving microstructures of crystal structures."
    },
    {
        "anchor": "Self-assembly of short DNA duplexes: from a coarse-grained model to\n  experiments through a theoretical link: Short blunt-ended DNA duplexes comprising 6 to 20 base pairs self-assemble\ninto polydisperse semi-flexible chains due to hydrophobic stacking interactions\nbetween terminal base pairs. Above a critical concentration, which depends on\ntemperature and duplex length, such chains order into liquid crystal phases.\nHere, we investigate the self-assembly of such double-helical duplexes with a\ncombined numerical and theoretical approach. We simulate the bulk system\nemploying the coarse-grained DNA model recently proposed by Ouldridge et al. [\nJ. Chem. Phys. 134, 08501 (2011) ]. Then we evaluate the input quantities for\nthe theoretical framework directly from the DNA model. The resulting\nparameter-free theoretical predictions provide an accurate description of the\nsimulation results in the isotropic phase. In addition, the theoretical\nisotropic-nematic phase boundaries are in line with experimental findings,\nproviding a route to estimate the stacking free energy.",
        "positive": "Shape, connectedness percolation and electrical conductivity of clusters\n  in suspensions of hard platelets: Using Monte Carlo simulations, we investigate how geometric percolation and\nelectrical conductivity in suspensions of hard conducting platelets are\naffected by the addition of platelets and their degree of spontaneous\nalignment. For aspect ratios $10, 25$ and $50$, we consistently observe a\nmonotonically decreasing percolation threshold as a function of volume\nfraction. In the nematic phase, the distribution of particles inside the\npercolating clusters becomes less spherically symmetric and the aspect ratio of\nthe clusters increases. However, the clusters are also anisotropically shaped\nin the isotropic phase, although their aspect ratio remains constant as a\nfunction of volume fraction. Mapping the percolating clusters of platelets to\nlinear resistor networks, and assigning unit conductance to all connections, we\nfind a constant conductivity both across the isotropic-nematic transition and\nin the respective stable phases. This behaviour is consistent with the other\nobserved topological properties of the networks. On the contrary, using an\nanisotropic conductance model, the network conductivity decreases with\nincreasing volume fraction in the isotropic, and further diminishes at the\nonset of the nematic. Hence, our observations consistently suggest that unlike\nfor rod-like fillers, the network structures that arise from platelet\nsuspensions are neither very sensitive to the particle aspect ratio nor to\nalignment, thus rendering platelets less versatile fillers for dispersion in\nconductive composites."
    },
    {
        "anchor": "Exploring the correlation between the folding rates of proteins and the\n  entanglement of their native states: The folding of a protein towards its native state is a rather complicated\nprocess. However there are empirical evidences that the folding time correlates\nwith the contact order, a simple measure of the spatial organisation of the\nnative state of the protein. Contact order is related to the average length of\nthe main chain loops formed by amino acids which are in contact. Here we argue\nthat folding kinetics can be influenced also by the entanglement that loops may\nundergo within the overall three dimensional protein structure. In order to\nexplore such possibility, we introduce a novel descriptor, which we call\n\"maximum intrachain contact entanglement\". Specifically, we measure the maximum\nGaussian entanglement between any looped portion of a protein and any other\nnon-overlapping subchain of the same protein, which is easily computed by\ndiscretized line integrals on the coordinates of the $C_{\\alpha}$ atoms. By\nanalyzing experimental data sets of two-state and multistate folders, we show\nthat also the new index is a good predictor of the folding rate. Moreover,\nbeing only partially correlated with previous methods, it can be integrated\nwith them to yield more accurate predictions.",
        "positive": "Parameter passing between Molecular Dynamics and continuum models for\n  droplets on solid substrates - The static case: We study equilibrium properties of polymer films and droplets on a solid\nsubstrate employing particle-based simulation techniques (Molecular Dynamics)\nand a continuum description. Parameter-passing techniques are explored that\nfacilitate a detailed comparison of the two models. In particular, the\nliquid-vapor, solid-liquid and solid-vapor interface tensions, and the\nDerjaguin or disjoining pressure are determined by Molecular Dynamics\nsimulations. This information is then introduced into continuum descriptions\naccounting for (i) the full curvature and (ii) a long-wave approximation of the\ncurvature (thin film model). A comparison of the dependence of the contact\nangle on droplet size indicates that the theories agree well if the contact\nangles are defined in a compatible manner."
    },
    {
        "anchor": "Protocol-dependent shear modulus of amorphous solids: We investigate the linear elastic response of amorphous solids to a shear\nstrain at zero temperature. We find that the response is characterized by at\nleast two distinct shear moduli. The first one, $\\mu_{\\rm ZFC}$, is associated\nwith the linear response of a single energy minimum. The second, $\\mu_{\\rm\nFC}$, is related to sampling, through plastic events, an ensemble of distinct\nenergy minima. We provide examples of protocols that allow one to measure both\nshear moduli. In agreement with a theoretical prediction based on the exact\nsolution in infinite spatial dimensions, the ratio $\\mu_{\\rm FC}/\\mu_{\\rm ZFC}$\nis found to vanish proportionally to the square root of pressure at the jamming\ntransition. Our results establish that amorphous solids are characterized by a\nrugged energy landscape, on which the infinite-dimensional solution can give\nuseful insight.",
        "positive": "Phase diagram of the adhesive hard sphere fluid: The phase behavior of the Baxter adhesive hard sphere fluid has been\ndetermined using specialized Monte Carlo simulations. We give a detailed\naccount of the techniques used and present data for the fluid-fluid coexistence\ncurve as well as parametrized fits for the supercritical equation of state and\nthe percolation threshold. These properties are compared with the existing\nresults of Percus-Yevick theory for this system."
    },
    {
        "anchor": "Probing anomalous relaxation by coherent multidimensional optical\n  spectroscopy: We propose to study the origin of algebraic decay of two-point correlation\nfunctions observed in glasses, proteins, and quantum dots by their nonlinear\nresponse to sequences of ultrafast laser pulses. Power-law spectral\nsingularities and temporal relaxation in two-dimensional correlation\nspectroscopy (2DCS) signals are predicted for a continuous time random walk\nmodel of stochastic spectral jumps in a two level system with a power-law\ndistribution of waiting times $\\psi (t)\\sim t^{-\\alpha -1}$. Spectroscopic\nsignatures of stationary ensembles for $1<\\alpha <2$ and aging effects in\nnonstationary ensembles with $0<\\alpha <1$ are identified.",
        "positive": "Effects of complex internal structures on rheology of multiple emulsions\n  through a generalized boundary integral method: As fine templates to prepare microcapsules, multiple emulsions with complex\ninternal structures have been generated through microfluidics. To study effects\nof layers, inner droplets and asymmetry of internal structures on rheology of\nmultiple emulsions, a generalized boundary integral method is developed to\ninvestigate multiple emulsions with orderly structures up to n layers and up to\nmi droplets in the i-th layer. Under a modest extensional flow, the\ncomplication of internal structures and the collision among inner droplets will\nsubject the particle to stronger shears. However, the particle will ease the\nadded tension through the simplification of internal structures\n(destabilization) such as coalescence or release of inner droplets. Since the\nrheology of multiple emulsions is sensitive to internal structures and their\nchange, modelling them as the core-shell droplets to obtain viscosity equation\nshould be modified by introducing the variable \"time\". Asymmetric internal\nstructures will induce oriented contact and merging of the outer and inner\ninterface. The start time of the interface merging can be controlled by\nadjusting the viscosity ratio and enhancing the asymmetry, which is promising\nin the controlled release of inner droplets for targeted drug delivery."
    },
    {
        "anchor": "Thermal stiffening of clamped elastic ribbons: We use molecular dynamics to study the vibrations of a thermally fluctuating\ntwo-dimensional elastic membrane clamped at both ends. We directly extract the\neigenmodes from resonant peaks in the frequency domain of the time-dependent\nheight and measure the dependence of the corresponding eigenfrequencies on the\nmicroscopic bending rigidity of the membrane, taking care also of the subtle\nrole of thermal contraction in generating a tension when the projected area is\nfixed. At finite temperatures we show that the effective (macroscopic) bending\nrigidity tends to a constant as the bare bending rigidity vanishes, consistent\nwith theoretical arguments that the large-scale bending rigidity of the\nmembrane arises from a strong thermal renormalization of the microscopic\nbending rigidity. Experimental realizations include covalently-bonded\ntwo-dimensional atomically thin membranes such as graphene and molybdenum\ndisulfide or soft matter systems such as the spectrin skeleton of red blood\ncells or diblock copolymers.",
        "positive": "In situ monitoring of block copolymer self-assembly through controlled\n  dialysis with light and neutron scattering detection: Solution self-assembly of amphiphilic block copolymers (BCs) is typically\nperformed by a solvent-to-water exchange. However, BC assemblies are often\ntrapped in metastable states depending on the mixing conditions such as the\nmagnitude and rate of water addition. BC self-assembly can be performed under\nnear thermodynamic control by dialysis, which accounts for a slow and gradual\nwater addition. In this Letter we report the use of a specifically designed\ndialysis cell to continuously monitor by dynamic light scattering and\nsmall-angle neutron scattering the morphological changes of PDMS-b-PEG BCs\nself-assemblies during THF-to-water exchange. The complete phase diagrams of\nnear-equilibrium structures can then be established. Spherical micelles first\nform before evolving to rod-like micelles and vesicles, decreasing the total\ndeveloped interfacial area of self-assembled structures in response to\nincreasing interfacial energy as the water content increases. The dialysis\nkinetics can be tailored to the time scale of BC self-assembly by modifying the\nmembrane pore size, which is of interest to study the interplay between\nthermodynamics and kinetics in self-assembly pathways."
    },
    {
        "anchor": "Towards a physics-based modelling of the electro-mechanical coupling in\n  EAPs: Due to the increasing number of industrial applications of electro-active\npolymers (EAPs), there is a growing need for electromechanical models which\naccurately capture their behavior. To this end, we compare the predicted\nbehavior of EAPs undergoing homogenous deformations according to three\nelectromechanical models. The first model is a continuum based model composed\nof the mechanical Gent model and a linear relationship between the electric\nfield and the polarization. The electrical and the mechanical responses\naccording to the second model are based on the polymer microstructure, whereas\nthe third model incorporates a neo-Hookean mechanical response and a\nmicrostructural based long-chains model for the electrical behavior. In the\nmicrostructural motivated models the integration from the microscopic to the\nmacroscopic levels is accomplished by the micro-sphere technique. Four types of\nhomogeneous boundary conditions are considered and the behaviors determined\naccording to the three models are compared. The differences between the\npredictions of the models are discussed, highlighting the need for an in-depth\ninvestigation of the relations between the structure and the behaviors of the\nEAPs at microscopic level and their overall macroscopic response.",
        "positive": "Derivation of Two-fluid Model Based on Onsager Principle: Using Onsager variational principle, we study the dynamic coupling between\nthe stress and the composition in polymer solution. In the original derivation\nof the two-fluid model [Doi and Onuki, J. Phys. II France {\\bf 2}, 1631\n(1992)], the polymer stress was introduced \\emph{a priopri}, therefore a\nconstitutive equation is required to close the equations. Based on our previous\nstudy of viscoelastic fluids with homogeneous composition [Phys. Rev. Fluids\n{\\bf 3}, 084004 (2018)], we start with a dumbbell model for the polymer, and\nderive all dynamic equations using the Onsager variational principle."
    },
    {
        "anchor": "Controlling morphology in hybrid isotropic/patchy particle assemblies: Brownian Dynamics is used to study self-assembly in a hybrid system of\nistotropic particles (IPs), combined with anisotropic building blocks that\nrepresent special \"designer particles\". Those are modeled as spherical patchy\nparticles (PPs) with binding only allowed between their patches and IPs. In\nthis study, two types of PPs are considered: Octahedral PPs (Oh-PPs) and Square\nPPs (Sq-PPs), with octahedral and square arrangements of patches, respectively.\nThe self-assembly is additionally facilitated by the simulated annealing\nprocedure. The resultant structures are characterized by a combination of local\ncorrelations in cubatic ordering, and a symmetry-specific variation of bond\norientation order parameters (SymBOPs). By varying the PP/IP size ratio, we\ndetected a sharp crossover between two distinct morphologies, in both types of\nsystems. High symmetry phases, NaCl crystal for Oh-PP and square lattice for\nSq-PP, are observed for larger size ratios. For smaller ones, the dominant\nmorphologies are significantly different, e.g., Oh-PPs form a compact amorphous\nstructure with predominantly Face-to-Face orientation of neighboring PPs.\nUnusually for a morphology without a long range order, it is still possible to\nidentify well organized coherent clusters of this structure, thanks to the\nadoption of our SymBOP-based characterization.",
        "positive": "Topological digestion drives time-varying rheology of entangled DNA\n  fluids: Understanding and controlling the rheology of polymeric complex fluids that\nare pushed out-of-equilibrium is a fundamental problem in both industry and\nbiology. For example, to package, repair, and replicate DNA, cells use enzymes\nto constantly manipulate DNA topology, length, and structure. Inspired by this,\nhere we engineer and study DNA-based complex fluids that undergo\nenzymatically-driven topological and architectural alterations via restriction\nendonuclease (RE) reactions. We show that these systems display time-dependent\nrheological properties that depend on the concentrations and properties of the\ncomprising DNA and REs. Through time-resolved microrheology experiments and\nBrownian Dynamics simulations, we show that conversion of supercoiled to linear\nDNA topology leads to a monotonic increase in viscosity. On the other hand, the\nviscosity of entangled linear DNA undergoing fragmentation displays a universal\ndecrease that we rationalize using living polymer theory. Finally, to showcase\nthe tunability of these behaviours, we design a DNA fluid that exhibits a\ntime-dependent increase, followed by a temporally-gated decrease, of its\nviscosity. Our results present a class of polymeric fluids that leverage\nnaturally occurring enzymes to drive diverse time-varying rheology by\nperforming architectural alterations to the constituents."
    },
    {
        "anchor": "Transverse NMR relaxation as a probe of mesoscopic structure: Transverse NMR relaxation in a macroscopic sample is shown to be extremely\nsensitive to the structure of mesoscopic magnetic susceptibility variations.\nSuch a sensitivity is proposed as a novel kind of contrast in the NMR\nmeasurements. For suspensions of arbitrary shaped paramagnetic objects, the\ntransverse relaxation is found in the case of a small dephasing effect of an\nindividual object. Strong relaxation rate dependence on the objects' shape\nagrees with experiments on whole blood. Demonstrated structure sensitivity is a\ngeneric effect that arises in NMR relaxation in porous media, biological\nsystems, as well as in kinetics of diffusion limited reactions.",
        "positive": "Noise-induced quenched disorder in dense active systems: We report and characterize the emergence of a noise-induced state of quenched\ndisorder in a generic model describing a dense sheet of active polar disks with\nnon-isotropic rotational and translational dynamics. In this state, randomly\noriented self-propelled disks become jammed, only displaying small fluctuations\nabout their mean positions and headings. The quenched disorder phase appears at\nintermediate noise levels, between the two states that typically define the\nflocking transition (a standard disordered state that displays continuously\nchanging headings due to rotational diffusion and a polar order state of\ncollective motion). We find that the angular fluctuations in this dense system\nfollow an Ornstein-Uhlenbeck process leading to retrograde forces that oppose\nself-propulsion, and determine its properties. Using this result, we explain\nthe mechanism behind the emergence of the quenched state and compute\nanalytically its critical noise, showing that it matches our numerical\nsimulations. We argue that this novel type of state could be observed in a\nbroad range of natural and artificial dense active systems with repulsive\ninteractions."
    },
    {
        "anchor": "Chemistry in Motion: Tiny Synthetic Motors: In this Account, we describe how synthetic motors that operate by\nself-diffusiophoresis make use of a self-generated concentration gradient to\ndrive motor motion. A description of propulsion by self-diffusiophoresis is\npresented for Janus particle motors comprising catalytic and noncatalytic\nfaces. The properties of the dynamics of chemically powered motors are\nillustrated by presenting the results of particle-based simulations of\nsphere-dimer motors constructed from linked catalytic and noncatalytic spheres.\nThe geometries of both Janus and sphere-dimer motors with asymmetric catalytic\nactivity support the formation of concentration gradients around the motors.\nBecause directed motion can occur only when the system is not in equilibrium,\nthe nature of the environment and the role it plays in motor dynamics are\ndescribed. Rotational Brownian motion also acts to limit directed motion, and\nit has especially strong effects for very small motors. We address the\nfollowing question: how small can motors be and still exhibit effects due to\npropulsion, even if only to enhance diffusion? Synthetic motors have the\npotential to transform the manner in which chemical dynamical processes are\ncarried out for a wide range of applications.",
        "positive": "Minimal Surfaces, Screw Dislocations and Twist Grain Boundaries: Large twist-angle grain boundaries in layered structures are often described\nby Scherk's first surface whereas small twist-angle grain boundaries are\nusually described in terms of an array of screw dislocations. We show that\nthere is no essential distinction between these two descriptions and that, in\nparticular, their comparative energetics depends crucially on the core\nstructure of their screw-dislocation topological defects."
    },
    {
        "anchor": "Tension dynamics in semiflexible polymers. Part II: Scaling solutions\n  and applications: In Part I of this contribution, a systematic coarse-grained description of\nthe dynamics of a weakly-bending semiflexible polymer was developed. Here, we\ndiscuss analytical solutions of the established deterministic partial\nintegro-differential equation for the spatio-temporal relaxation of the\nbackbone tension. For prototypal experimental situations, such as the sudden\napplication or release of a strong external pulling force, it is demonstrated\nthat the tensile dynamics reflects the self-affine conformational fluctuation\nspectrum in a variety of intermediate asymptotic power laws. Detailed and\nexplicit analytical predictions for the tension propagation and relaxation and\ncorresponding results for common observables, such as the end-to-end distance,\nare obtained.",
        "positive": "Spontaneous order in ensembles of rotating magnetic droplets: Ensembles of elongated magnetic droplets in a rotating field are studied\nexperimentally. In a given range of field strength and frequency the droplets\nform rotating structures with a triangular order - rotating crystals. A model\nis developed to describe ensembles of several droplets, taking into account the\nhydrodynamic interactions between the rotating droplets in the presence of a\nsolid wall below the rotating ensemble. A good agreement with the\nexperimentally observed periodic dynamics for an ensemble of four droplets is\nobtained. During the rotation, the tips of the elongated magnetic droplets\napproach close to one another. An expression is derived that gives the magnetic\ninteraction between such droplets by taking into account the coulombian forces\nbetween magnetic charges on the droplet tips."
    },
    {
        "anchor": "Structure and dynamics of a polymer-nanoparticle composite: Effect of\n  nanoparticle size and volume fraction: We use molecular dynamics simulations to study a semidilute, unentangled\npolymer solution containing well dispersed, weakly attractive nanoparticles\n(NP) of size ($\\sigma_N$) smaller than the polymer radius of gyration $R_g$. We\nfind that if $\\sigma_N$ is larger than the monomer size the polymers swell,\nwhile smaller NPs cause chain contraction. The diffusion coefficient of polymer\nchains ($D_p$) and NPs ($D_N$) decreases if the volume fraction $\\phi_N$ is\nincreased. The decrease of $D_p$ can be well described in terms of a\nconfinement parameter, while $D_N$ shows a more complex dependence on\n$\\sigma_N$, which results from an interplay between energetic and entropic\neffects. When $\\phi_N$ exceeds a $\\sigma_N$-dependent value, the NPs are no\nlonger well dispersed and $D_N$ and $D_p$ increase if $\\phi_N$ is increased.",
        "positive": "Density Functional Theory of Bosons in a Trap: A time-dependent Kohn-Sham (KS) like theory is presented for N bosons in thre\ne and lower-dimensional traps. We derive coupled equations, which allow one to\ncalculate the energies of elementary excitations. A rigorous proof is given to\nshow that the KS like equation correctly describes properties of the\none-dimensional condensate of impenetrable bosons in a general time-dependent\nharmonic trap in the larg N limit."
    },
    {
        "anchor": "Erythrocyte sedimentation: Effect of aggregation energy on gel structure\n  during collapse: The erythrocyte (or red blood cell) sedimentation rate (ESR) is commonly\ninterpreted as a measure of cell aggregation and as a biomarker of\ninflammation. It is well known that an increase of fibrinogen concentration, an\naggregation-inducing protein for erythrocytes, leads to an increase of the\nsedimentation rate of erythrocytes, which is generally explained through the\nformation and faster settling of large disjoint aggregates. However, many\naspects of erythrocyte sedimentation conform well with the collapse of a\ncolloidal gel rather than with the sedimentation of disjoint aggregates. Using\nexperiments and cell-level numerical simulations, we systematically investigate\nthe dependence of ESR on fibrinogen concentration and its relation to the\nmicrostructure of the gel-like erythrocyte suspension. We show that for\nphysiological aggregation interactions, an increase in the attraction strength\nbetween cells results in a cell network with larger void spaces. This\ngeometrical change in the network structure occurs due to anisotropic shape and\ndeformability of erythrocytes and leads to an increased gel permeability and\nfaster sedimentation. Our results provide a comprehensive relation between the\nESR and the cell-level structure of erythrocyte suspensions and support the gel\nhypothesis in the interpretation of blood sedimentation.",
        "positive": "A survey of liquid crystalline oxadiazoles: We propose a survey of those oxadiazole compounds, which are mesogenic. We\nwill see that they can have bend-shaped molecules, a biaxial nematic phase, or\nother interesting peculiarities in the nematic and smectic phase. With large\nelectric dipoles and luminescent properties, these materials are also very\nappealing for technological applications."
    },
    {
        "anchor": "Rotation-induced macromolecular spooling of DNA: Genetic information is stored in a linear sequence of base-pairs; however,\nthermal fluctuations and complex DNA conformations such as folds and loops make\nit challenging to order genomic material for in vitro analysis. In this work,\nwe discover that rotation-induced macromolecular spooling of DNA around a\nrotating microwire can monotonically order genomic bases, overcoming this\nchallenge. We use single-molecule fluorescence microscopy to directly visualize\nlong DNA strands deforming and elongating in shear flow near a rotating\nmicrowire, in agreement with numerical simulations. While untethered DNA is\nobserved to elongate substantially, in agreement with our theory and numerical\nsimulations, strong extension of DNA becomes possible by introducing tethering.\nFor the case of tethered polymers, we show that increasing the rotation rate\ncan deterministically spool a substantial portion of the chain into a fully\nstretched, single-file conformation. When applied to DNA, the fraction of\ngenetic information sequentially ordered on the microwire surface will increase\nwith the contour length, despite the increased entropy. This ability to handle\nlong strands of DNA is in contrast to modern DNA sample preparation\ntechnologies for sequencing and mapping, which are typically restricted to\ncomparatively short strands resulting in challenges in reconstructing the\ngenome. Thus, in addition to discovering new rotation-induced macromolecular\ndynamics, this work inspires new approaches to handling genomic-length DNA\nstrands.",
        "positive": "Snap-off production of monodisperse droplets: We introduce a novel technique to produce monodisperse droplets through the\nsnap-off mechanism. The methodology is simple, versatile, and requires no\nspecialized or expensive components. The droplets produced have polydispersity\n<1% and can be as small as 2.5 $\\mu$m radius. A convenient feature is that the\ndroplet size is constant over a 100-fold change in flow rate, while at higher\nflows the droplet size can be continuously adjusted."
    },
    {
        "anchor": "Avalanches on a conical bead pile: scaling with tuning parameters: Uniform spherical beads were used to explore the behavior of a granular\nsystem near its critical angle of repose on a conical bead pile. We found two\ntuning parameters that could take the system to a critical point where a simple\npower-law described the avalanche size distribution as predicted by\nself-organized criticality, which proposed that complex dynamical systems\nself-organize to a critical point without need for tuning. Our distributions\nwere well described by a simple power-law with the power {\\tau} = 1.5 when\ndropping beads slowly onto the apex of a bead pile from a small height.\nHowever, we could also move the system from the critical point using either of\ntwo tuning parameters: the height from which the beads fell onto the top of the\npile or the region over which the beads struck the pile. As the drop height\nincreased, the system did not reach the critical point yet the resulting\ndistributions were independent of the bead mass, coefficient of friction, or\ncoefficient of restitution. All our apex-dropping distributions for any type of\nbead (glass, stainless steel, zirconium) showed universality by scaling onto a\ncommon curve with {\\tau} = 1.5 and {\\sigma} = 1.0, where 1/{\\sigma} is the\npower of the tuning parameter. From independent calculations using the moments\nof the distribution, we find values for {\\tau} = 1.6 \\pm 0.1 and {\\sigma} =\n0.91 \\pm 0.15. When beads were dropped across the surface of the pile instead\nof solely on the apex, then the system also moved from the critical point and\nagain the avalanche size distributions fell on a common curve when scaled\nsimilarly using the same values of {\\tau} and {\\sigma}. We also observed that\nan hcp structure on the base of the pile caused an emergent structure in the\npile that had six faces with some fcc or hcp structure.",
        "positive": "Fluidisation and plastic activity in a model soft-glassy material\n  flowing in micro-channels with rough walls: By means of mesoscopic numerical simulations of a model soft-glassy material,\nwe investigate the role of boundary roughness on the flow behaviour of the\nmaterial, probing the bulk/wall and global/local rheologies. We show that the\nroughness reduces the wall slip induced by wettability properties and acts as a\nsource of fluidisation for the material. A direct inspection of the plastic\nevents suggests that their rate of occurrence grows with the fluidity field,\nreconciling our simulations with kinetic elasto-plastic descriptions of jammed\nmaterials. Notwithstanding, we observe qualitative and quantitative differences\nin the scaling, depending on the distance from the rough wall and on the\nimposed shear. The impact of roughness on the orientational statistics is also\nstudied."
    },
    {
        "anchor": "Nonlinear Low-to-High Frequency Energy Cascades in Diatomic Granular\n  Crystals: We study wave propagation in strongly nonlinear 1D diatomic granular crystals\nunder an impact load. Depending on the mass ratio of the `light' to `heavy'\nbeads, this system exhibits rich wave dynamics from highly localized traveling\nwaves to highly dispersive waves featuring strong attenuation. We\nexperimentally demonstrate the nonlinear resonant and anti-resonant\ninteractions of particles and verify that the nonlinear resonance results in\nstrong wave attenuation, leading to highly efficient nonlinear energy cascading\nwithout relying on material damping. In this process, mechanical energy is\ntransferred from low to high frequencies, while propagating waves emerge in\nboth ordered and chaotic waveforms via a distinctive spatial cascading. This\nenergy transfer mechanism from lower to higher frequencies and wavenumbers is\nof particular significance towards the design of novel nonlinear acoustic\nmetamaterials with inherently passive energy redistribution properties.",
        "positive": "Lifetime of dynamic heterogeneities in a binary Lennard-Jones mixture: A four-time correlation function was calculated using a computer simulation\nof a binary Lennard-Jones mixture. The information content of the four-time\ncorrelation function is similar to that of four-time correlation functions\nmeasured in NMR experiments. The correlation function selects a sub-ensemble\nand analyzes its dynamics after some waiting time. The lifetime of the\nsub-ensemble selected by the four-time correlation function is calculated, and\ncompared to the lifetimes of slow sub-ensembles selected using two different\ndefinitions of mobility, and to the $\\alpha$ relaxation time."
    },
    {
        "anchor": "Reorientation dynamics of microswimmers at fluid-fluid interfaces: We study the orientational and translational dynamics of spherical\nmicroswimmers trapped at fluid interfaces, in terms of the force dipole and\nsource dipole components of their flow field. Using numerical simulations and\nanalytical calculations, we show that the force dipole exerts a torque,\norienting pushers parallel to the interface, and pullers in normal direction.\nThe source dipole results in particle rotation only for a finite viscosity\ncontrast between the two fluids, in agreement with previous studies. The\nsuperposition of these two contributions leads to an rotational dynamics with a\nsteady-state orientation that depends on the relative magnitudes of the force\nand source dipoles. In the general case, swimmers with weak force dipoles and\nstrong pullers are observed to align perpendicular to the interface and become\nstationary, while strong pushers have a finite inclination angle towards the\nlower viscosity fluid and swim along the interface.",
        "positive": "Rheology of Pseudomonas fluorescens biofilms: from experiments to\n  predictive DPD mesoscopic modelling: Bacterial biofilms mechanically behave as viscoelastic media consisting of\nmicron-sized bacteria crosslinked to a selfproduced network of extracellular\npolymeric substances (EPS) embedded in water. Structural principles for\nnumerical modelling aim at describing mesoscopic viscoelasticity without\nloosing detail on the underlying interactions existing in wide regimes of\ndeformation under hydrodynamic stress. Here we approach the computational\nchallenge to model bacterial biofilms for predictive mechanics in silico under\nvariable stress conditions. Up-to-date models are not entirely satisfactory due\nto the plethora of parameters required to make them functioning under the\neffects of stress. As guided by the structural depiction gained in a previous\nwork with Pseudomonas fluorescens (Jara et al. Front. Microbiol. (2021)), we\npropose a mechanical modeling by means of Dissipative Particle Dynamics (DPD),\nwhich captures the essentials of the topological and compositional interactions\nbetween bacteria particles and crosslinked EPS-embedding under imposed shear.\nThe P. fluorescens biofilms have been modeled under mechanical stress mimicking\nshear stresses as undergone in vitro. The predictive capacity for mechanical\nfeatures in DPD-simulated biofilms has been investigated by varying the\nexternally imposed field of shear strain at variable amplitude and frequency.\nThe parametric map of essential biofilm ingredients has been explored by making\nthe rheological responses to emerge among conservative mesoscopic interactions\nand frictional dissipation in the underlying microscale. The proposed coarse\ngrained DPD simulation qualitatively catches the rheology of the P. fluorescens\nbiofilm over several decades of dynamic scaling."
    },
    {
        "anchor": "Time-Resolved Emission Study of a Thiophene-Modified Fluorescent\n  Nucleoside in Solution and within Multiply-Modified Oligodeoxynucleotides: Steady-state and time-resolved emission techniques were employed to study the\nphotophysical properties of 5-(thien-2-yl)-2'-deoxyuridine (dUTh), an\nisomorphic fluorescent nucleoside analog. We found that the emission lifetime\nof dUTh is dependent upon the solvent viscosity and obeys the F\\\"orster-Hoffman\nrelation over a wide range of temperatures in 1-propanol, a glass-forming\nliquid. Upon incorporation into oligodeoxynucleotides, the average emission\nlifetime significantly increases, and the decay is non-exponential. We use a\nnon-radiative decay model that takes into account the twist angle of the\nthiophene ring to fit the time-resolved emission decay curves.",
        "positive": "Dynamical membrane curvature instability controlled by intermonolayer\n  friction: We study a dynamical curvature instability caused by a local chemical\nmodification of a phospholipid membrane. In our experiments, a basic solution\nis microinjected close to a giant unilamellar vesicle, which induces a local\nchemical modification of some lipids in the external monolayer of the membrane.\nThis modification causes a local deformation of the vesicle, which then\nrelaxes. We present a theoretical description of this instability, taking into\naccount both the change of the equilibrium lipid density and the change of the\nspontaneous membrane curvature induced by the chemical modification. We show\nthat these two types of changes of the membrane properties yield different\ndynamics. In contrast, it is impossible to distinguish them when studying the\nequilibrium shape of a vesicle subjected to a global modification. In our\nmodel, the longest relaxation timescale is related to the intermonolayer\nfriction, which plays an important part when there is a change in the\nequilibrium density in one monolayer. We compare our experimental results to\nthe predictions of our model by fitting the measured time evolution of the\ndeformation height to the solution of our dynamical equations. We obtain good\nagreement between theory and experiments. Our fits enable us to estimate the\nintermonolayer friction coefficient, yielding values that are consistent with\nprevious measurements."
    },
    {
        "anchor": "Low energy states of a semiflexible polymer chain with attraction and\n  the whip-toroid transitions: Based on our previous paper [cond-mat/0507477], we establish a general model\nfor the whip-toroid transitions of a semiflexible homopolymer chain using the\npath integral method and the O(3) nonlinear sigma model on a line segment with\nthe local inextensibility constraint. We exactly solve the energy levels of\nclassical solutions, and show that some of its classical configurations exhibit\ntoroidal forms, and the system has phase transitions from a whip to toroidal\nstates with a conformation parameter $c=\\frac{W}{2 l} (\\frac{L}{2\\pi})^2$. We\nalso discuss the stability of the toroid states and propose the low-energy\neffective Green function. Finally, with the finite size effect on the toroid\nstates, predicted toroidal properties are successfully compared to experimental\nresults of DNA condensation.",
        "positive": "Coalescence in two-dimensional foams: a purely statistical process: While coalescence is ultimately the most drastic destabilization process in\nfoams, its underlying processes are still unclear. To better understand them,\nwe track individual coalescence events in two-dimensional foams at controlled\ncapillary pressure. We obtain statistical information revealing the influence\nof the different parameters which have been previously proposed to explain\ncoalescence. Our main conclusion is that coalescence probability is simply\nproportional to the area of the thin film separating two bubbles, suggesting\nthat coalescence is mostly stochastic."
    },
    {
        "anchor": "Thermotropic Nematic and Smectic Order in Silica Glass Nanochannels: Optical birefringence measurements on a rod-like liquid crystal (8OCB),\nimbibed in silica channels (7 nm diameter), are presented and compared to the\nthermotropic bulk behavior. The orientational and positional order of the\nconfined liquid evolves continuously at the paranematic-to-nematic and sizeably\nbroadened at the nematic-to-smectic order transition, resp., in contrast to the\ndiscontinuous and well-defined second-order character of the bulk transitions.\nA Landau-de-Gennes analysis reveals identical strengths of the nematic and\nsmectic ordering fields (imposed by the walls) and indicates that the smectic\norder is more affected by quenched disorder (originating in channel tortuosity\nand roughness) than the nematic transition.",
        "positive": "Friction and dilatancy in immersed granular matter: The friction of a sliding plate on a thin immersed granular layer obeys\nAmonton-Coulomb law. We bring to the fore a large set of experimental results\nwhich indicate that, over a few decades of values, the effective dynamical\nfriction-coefficient depends neither on the viscosity of the interstitial fluid\nnor on the size of beads in the sheared layer, which bears out the analogy with\nthe solid-solid friction in a wide range of experimental parameters. We\naccurately determine the granular-layer dilatancy, which dependance on the\ngrain size and slider velocity can be qualitatively accounted by considering\nthe rheological behaviour of the whole slurry. However, additional results,\nobtained after modification of the grain surface by a chemical treatment,\ndemonstrate that the theoretical description of the flow properties of granular\nmatter, even immersed, requires the detailed properties of the grain surface to\nbe taken into account."
    },
    {
        "anchor": "Enhanced bacterial swimming speeds in macromolecular polymer solutions: The locomotion of swimming bacteria in simple Newtonian fluids can\nsuccessfully be described within the framework of low Reynolds number\nhydrodynamics. The presence of polymers in biofluids generally increases the\nviscosity, which is expected to lead to slower swimming for a constant\nbacterial motor torque. Surprisingly, however, several experiments have shown\nthat bacterial speeds increase in polymeric fluids, and there is no clear\nunderstanding why. Therefore we perform extensive coarse-grained simulations of\na bacterium swimming in explicitly modeled solutions of macromolecular polymers\nof different lengths and densities. We observe an increase of up to 60% in\nswimming speed with polymer density and demonstrate that this is due to a\ndepletion of polymers in the vicinity of the bacterium leading to an effective\nslip. However this in itself cannot predict the large increase in swimming\nvelocity: coupling to the chirality of the bacterial flagellum is also\nnecessary.",
        "positive": "Ions in mixed dielectric solvents: density profiles and osmotic pressure\n  between charged interfaces: The forces between charged macromolecules, usually given in terms of osmotic\npressure, are highly affected by the intervening ionic solution. While in most\ntheoretical studies the solution is treated as a homogeneous structureless\ndielectric medium, recent experimental studies concluded that, for a bathing\nsolution composed of two solvents (binary mixture), the osmotic pressure\nbetween charged macromolecules is affected by the binary solvent composition.\nBy adding local solvent composition terms to the free energy, we obtain a\ngeneral expression for the osmotic pressure, in planar geometry and within the\nmean-field framework. The added effect is due to the permeability inhomogeneity\nand nonelectrostatic short-range interactions between the ions and solvents\n(preferential solvation). This effect is mostly pronounced at small distances\nand leads to a reduction in the osmotic pressure for macromolecular separations\nof the order 1--2 nm. Furthermore, it leads to a depletion of one of the two\nsolvents from the charged macromolecules (modeled as planar interfaces).\nLastly, by comparing the theoretical results with experimental ones, an\nexplanation based on preferential solvation is offered for recent experiments\non the osmotic pressure of DNA solutions."
    },
    {
        "anchor": "Symplectic algorithms for simulations of rigid body systems using the\n  exact solution of free motion: Elegant integration schemes of second and fourth order for simulations of\nrigid body systems are presented which treat translational and rotational\nmotion on the same footing. This is made possible by a recent implementation of\nthe exact solution of free rigid body motion. The two schemes are\ntime-reversible, symplectic, and exactly respect conservation principles for\nboth the total linear and angular momentum vectors. Simulations of simple test\nsystems show that the second order scheme is stable and conserves all constants\nof the motion to high precision. Furthermore, the schemes are demonstrated to\nbe more accurate and efficient than existing methods, except for high\ndensities, in which case the second order scheme performs at least as well,\nshowing their general applicability. Finally, it is demonstrated that the\nfourth order scheme is more efficient than the second order scheme provided the\ntime step is smaller than a system-dependent threshold value.",
        "positive": "Thermoresponsive stiffening with microgel particles in a semiflexible\n  fibrin network: We report temperature-responsive soft composites of semiflexible biopolymer\nnetworks (fibrin) containing dispersed microgel colloidal particles of\npoly(N-isopropylacrylamide) (pNIPAM) that undergo a thermodynamically driven\nde-swelling transition above a Lower Critical Solution Temperature (LCST).\nUnlike standard polymer-particle composites, decreasing the inclusion volume of\nthe particles (by increasing temperature)is concomitant with a striking\nincrease of the overall elastic stiffness of the composite. We observe such a\nbehavior over a wide composition space. The composite elastic shear modulus\nreversibly stiffens by up to 10-fold over a small change in temperature from\n25-35{\\deg}C. In isolation, the fibrin network and microgel suspension both\nsoften with increased temperature, making the stiffening of the composites\nparticularly significant. We hypothesize that stiffening is caused by\ncontracting microgel particles adsorbing on the fibrin filaments and modifying\nthe structure of the semiflexible network. We develop two phenomenological\nmodels that quantify this hypothesis in physically distinct manners, and the\nderived predictions are qualitatively consistent with our experimental data"
    },
    {
        "anchor": "Formation and Fluctuation of Two-dimensional Dodecagonal Quasicrystal: The self-assembly of two-dimensional dodecagonal quasicrystal (DDQC) from\npatchy particles are investigated by Brownian dynamics simulations. The patchy\nparticle has a five-fold rotational symmetry pattern described by the spherical\nharmonics $Y_{55}$. From the formation of the DDQC obtained by an annealing\nprocess, we find the following mechanism. The early stage of the dynamics is\ndominated by hexagonal structures. Then, nucleation of dodecagonal motifs\nappears by particle rearrangement, and finally the motifs expand whole system.\nThe transition from the hexagonal structure into the dodecagonal motif is made\nby the collective rational motion of the particles. The DDQC consists of\nclusters of dodecagonal motifs, which can be classified into several packing\nstructures. By the analyses of the DDQC under fixed temperature, we find the\nfluctuations are characterised by changes in the network of the dodecagonal\nmotifs. Finally we compare the DDQC assembled from the patchy particle system\nand isotropic particle system. The two systems both share a similar mechanism\nof the formation and fluctuation of DDQC.",
        "positive": "Resolving the relaxation complexity of vitrimers: time-temperature\n  superpositions of a time-temperature non-equivalent system: Vitrimers are polymer networks that, thanks to covalent bond exchange,\ncombine desirable properties of thermoplastic and thermosets, such as\nflowability and insolubility. For this reason, vitrimers are considered to be\ngood candidates for a number of innovative applications from self-healing soft\nrobots to hard reprocessable materials. All these applications are related to\nthe unusual thermomechanical behavior of vitrimers, consequence of the\nnon-trivial interplay between the polymer network dynamics and the thermally\nactivated chemical link exchange. Here we use solid-state rheology to\ninvestigate the properties of a recently developed epoxy-based vitrimer. The\nrheological analysis demonstrates that the mechanical spectrum is composed of\ntwo relaxation processes with distinct activation energies which are associated\nwith glass dynamics and covalent bond exchange, respectively. This makes the\nmaterial thermo-rheologically complex and time temperature equivalence does not\napply. Nonetheless, thanks to mechanical spectral analysis in a wide range of\nstiffness, time and temperature, we are able to depict the\ntime-temperature-relaxation landscape in an enough precise way to account for\nthe two dynamical processes and recombine them to predict the mechanical moduli\nin a wide (virtually unlimited) interval of frequencies, from low temperatures\n(close to room temperature) to high temperatures (above the Tg)."
    },
    {
        "anchor": "Defect Textures in Polygonal Arrangements of Cylindrical Inclusions in\n  Cholesteric Liquid Crystal Matrices: A systematic computational and scaling analysis of defect textures in\npolygonal arrangement of cylindrical particles embedded in a cholesteric (Ch)\nliquid crystal matrix is performed using the Landau de Gennes model for chiral\nself assembly, with strong anchoring at the particles' surface. The defect\ntextures and LC phases observed are investigated as a function of chirality,\nelastic anisotropy, particle polygonal arrangement and particle size. The\npresence of a polygonal network made of N circular inclusions results in defect\ntextures of a net charge of -(N-2)/2 per unit polygonal cell. As the chirality\nincreases, the LC matrix shows the following transition sequence: weakly\ntwisted cholesterics, 2D blue phases with non-singular/ singular defect\nlattices, cholesteric phases with only disclinations, and fingerprint\ncholesteric textures with disclinations and dislocations. For monomeric\nmesogens at concentrations far from the I/Ch phase transition and low\nchirality, for a given symmetry of the LC phase, the particle with weaker\n(stronger) confinement results in a phase with lower (higher) elastic energy,\nwhile at high chirality the elastic energy of a LC phase is proportional to the\nnumber of particles that form the polygonal network. Thus, hexagonal\n(triangular) particle arrangement results in low elastic energy at low (high)\nchirality. For semiflexible polymeric mesogens (high elastic anisotropy),\ndefect textures with fewer disclinations/ dislocations arise but due to layer\ndistortions we find a higher elastic energy than monomeric mesogens. The\ndefects arising in the simulations and the texture rules established are in\nagreement with experimental observations in cellulosic liquid crystal analogues\nsuch as plant cell wall and helical biological polymeric mesophases made of\nDNA, PBLG and xanthan.",
        "positive": "Water under extreme confinement in graphene: Oscillatory dynamics,\n  structure, and hydration pressure explained as a function of the confinement\n  width: Graphene nanochannels are relevant for their possible applications, as in\nwater purification, and for the challenge of understanding how they change the\nproperties of confined liquids. Here, we use all-atom molecular dynamics\nsimulations to investigate water confined in an open graphene slit-pore as a\nfunction of its width $w$, down to sub-nm scale. We find that the water\ntranslational and rotational dynamics exhibits an oscillatory dependence on\n$w$, due to water layering. The oscillations in dynamics correlate with those\nin hydration pressure, which can be negative (hydrophobic attraction), or as\nhigh as $\\sim 1$ GPa, as seen in the experiments. At pore widths commensurable\nwith full layers (around $7.0$ \\AA\\ and $9.5$ \\AA\\ for one and two layers,\nrespectively), the free energy of the system has minima, and the hydration\npressure vanishes. These are the separations at which the dynamics of confined\nwater slows down. Nevertheless, the hydration pressure vanishes also where the\nfree energy has maxima, i.e., for those pore-widths which are incommensurable\nwith the formation of well-separated layers, as $w\\simeq 8.0$ \\AA. Around these\nvalues of $w$, the dynamics is faster than in bulk, with water squeezed out\nfrom the pore. This behavior has not been observed for simple liquids under\nconfinement, either for water in closed nano-pores. The decomposition of the\nfree energy clarifies the origins of the dynamics speedups and slowdowns. In\nparticular, we find that the nature of the slowdown depends on the number of\nwater layers: for two layers, it is due to the internal energy contribution, as\nin simple liquids, while for one layer, it has an entropic origin possibly due\nto the existence of a hydrogen-bond network in water. Our results shed light on\nthe mechanisms ruling the dynamics and thermodynamics of confined water and are\na guide for future experiments."
    },
    {
        "anchor": "Thermodynamics of Blue Phases In Electric Fields: We present extensive numerical studies to determine the phase diagrams of\ncubic and hexagonal blue phases in an electric field. We confirm the earlier\nprediction that hexagonal phases, both 2 and 3 dimensional, are stabilized by a\nfield, but we significantly refine the phase boundaries, which were previously\nestimated by means of a semi-analytical approximation. In particular, our\nsimulations show that the blue phase I -- blue phase II transition at fixed\nchirality is largely unaffected by electric field, as observed experimentally.",
        "positive": "Active and passive microrheology with large tracers in hard colloids: The dynamics of a tracer particle in a bath of quasi-hard colloidal spheres\nis studied by Langevin dynamics simulations and mode coupling theory (MCT); the\ntracer radius is varied from equal to up to 7 times larger than the bath\nparticles radius. In the simulations, two cases are considered: freely\ndiffusing tracer (passive microrheology) and tracer pulled with a constant\nforce (active microrheology). Both cases are connected by linear response\ntheory for all tracer sizes. It links both the stationary and transient regimes\nof the pulled tracer (for low forces) with the equilibrium correlation\nfunctions; the velocity of the pulled tracer and its displacement are obtained\nfrom the velocity auto-correlation function and the mean squared displacement,\nrespectively. The MCT calculations give insight into the physical mechanisms:\nAt short times, the tracer rattles in its cage of neighbours, with the\nfrequency increasing linearly with the tracer radius asymptotically. The\nlong-time tracer diffusion coefficient from passive microrheology, which agrees\nwith the inverse friction coefficient from the active case, arises from the\ntransport of transverse momentum around the tracer. It can be described with\nthe Brinkman equation for the transverse flow field obtained in extension of\nMCT, but cannot be recovered from the MCT kernel coupling to densities only.\nThe dynamics of the bath particles is also studied; for the unforced tracer the\ndynamics is unaffected, irrespective of the distance from the tracer. When the\ntracer is pulled, the velocity field in the bath decays with the distance from\nthe tracer as 1/r3, as predicted by the Brinkman model, but different from the\ncase of a Newtonian fluid."
    },
    {
        "anchor": "Nanoparticle-lipid interaction: Job scattering plots to differentiate\n  vesicle aggregation from supported lipid bilayer formation: The impact of nanomaterials on lung fluids or on the plasma membrane of\nliving cells has prompted researchers to examine the interactions between\nnanoparticles and lipid vesicles. Recent studies have shown that\nnanoparticle-lipid interaction leads to a broad range of structures including\nsupported lipid bilayers (SLB), particles adsorbed at the surface or\ninternalized inside vesicles, and mixed aggregates. Today, there is a need to\nhave simple protocols that can readily assess the nature of structures obtained\nfrom particles and vesicles. Here we apply the method of continuous variation\nfor measuring Job scattering plots and provide analytical expressions for the\nscattering intensity in various scenarios. The result that emerges from the\ncomparison between modeling and experimental measurements is that\nelectrostatics plays a key role in the association, but it is not sufficient to\ninduce the formation of supported lipid bilayers.",
        "positive": "Dynamics of a dielectric droplet suspended in a magnetic fluid in\n  electric and magnetic fields: The behavior of a microdrop of dielectric liquid suspended in a magnetic\nfluid and exposed to the action of electric and magnetic fields is studied\nexperimentally. With increasing electric field, the deformation of droplets\ninto oblate ellipsoid, toroid and curved toroid was observed. At the further\nincrease in the electric field, the bursting of droplets was also revealed. The\nelectrorotation of deformed droplets was observed and investigated. The\ninfluence of an additional magnetic field on the droplet dynamics was studied.\nThe main features of the droplet dynamics were interpreted and theoretically\nexamined."
    },
    {
        "anchor": "Large-scale simulations of fluctuating biological membranes: We present a simple, and physically motivated, coarse-grained model of a\nlipid bilayer, suited for micron scale computer simulations. Each ~25 nm^2\npatch of bilayer is represented by a spherical particle. Mimicking forces of\nhydrophobic association, multi-particle interactions suppress the exposure of\neach sphere's equator to its implicit solvent surroundings. The requirement of\nhigh equatorial density stabilizes two-dimensional structures without\nnecessitating crystalline order, allowing us to match both the elasticity and\nfluidity of natural lipid membranes. We illustrate the model's versatility and\nrealism by characterizing membrane response to a prodding nanorod.",
        "positive": "A formally exact field theory for classical systems at equilibrium: We propose a formally exact statistical field theory for describing classical\nfluids with ingredients similar to those introduced in quantum field theory. We\nconsider the following essential and related problems : i) how to find the\ncorrect field functional (Hamiltonian) which determines the partition function,\nii) how to introduce in a field theory the equivalent of the indiscernibility\nof particles, iii) how to test the validity of this approach. We can use a\nsimple Hamiltonian in which a local functional transposes, in terms of fields,\nthe equivalent of the indiscernibility of particles. The diagrammatic expansion\nand the renormalization of this term is presented. This corresponds to a non\nstandard problem in Feynman expansion and requires a careful investigation.\nThen a non-local term associated with an interaction pair potential is\nintroduced in the Hamiltonian. It has been shown that there exists a mapping\nbetween this approach and the standard statistical mechanics given in terms of\nMayer function expansion. We show on three properties (the chemical potential,\nthe so-called contact theorem and the interfacial properties) that in the field\ntheory the correlations are shifted on non usual quantities. Some perspectives\nof the theory are given."
    },
    {
        "anchor": "On the critical behavior of the specific heat in glass-formers: We show numeric evidence that, at low enough temperatures, the potential\nenergy density of a glass-forming liquid fluctuates over length scales much\nlarger than the interaction range. We focus on the behavior of translationally\ninvariant quantities. The growing correlation length is unveiled by studying\nthe Finite Size effects. In the thermodynamic limit, the specific heat and the\nrelaxation time diverge as a power law. Both features point towards the\nexistence of a critical point in the metastable supercooled liquid phase.",
        "positive": "Decoupled algorithm for the multicomponent potential theory of\n  adsorption of gas mixtures: In this paper, we present a new implementation of the Multicomponent\nPotential Theory of Adsorption model. The proposed interpretation establishes a\nclear cut between parameters that depends on the adsorbent from those depending\non the adsorbate, which leads to a better understanding of the parameters\nsignification. The interdependence between pure isotherms is eliminated, which\nmean that each component can be individually finely adjusted. This new approach\nwas tested against 14 datasets for a total of 510 experimental mixture\nadsorption data of CH4, CO2, N2, H2, O2, H2S, C2H6, C3H6 and C3H8 on activated\ncarbons, MOF and zeolites. A slight improvement of 4.67% on excess adsorption\npredictions was found, leading to an overall average error of 6.97% for total\nexcess adsorption and 15.30% for combined mixtures and components excess\nadsorption predictions."
    },
    {
        "anchor": "Scalar model for frictional precursors dynamics: Recent experiments indicate that frictional sliding occurs by the nucleation\nof detachment fronts at the contact interface that may appear well before the\nonset of global sliding. This intriguing precursory activity is not accounted\nfor by traditional friction theories but is extremely important for friction\ndominated geophysical phenomena such as earthquakes, landslides or avalanches.\nHere we simulate the onset of slip of a three dimensional elastic body resting\non a surface and show that experimentally observed frictional precursors depend\nin a complex non-universal way on the sample geometry and the loading\nconditions. Our model satisfies Archard's law and Amontons' first and second\nlaws, reproducing with remarkable precision the real contact area dynamics, the\nprecursors' envelope dynamics prior to the transition to sliding, and the\nnormal and shear internal stress distributions close to the slider-substrate\ninterface. Moreover, it allows to assess which experimental features can be\nattributed to the elastic equilibrium, and which are attributed to the\nout-of-equilibrium dynamics, suggesting that precursory activity is an\nintrinsically quasi-static physical process. A direct calculation of the\nevolution of the Coulomb stress before and during precursors nucleation shows\nlarge variations across the sample, which helps to explain why earthquake\nforecasting methods based only on accumulated slip and Coulomb stress\nmonitoring are often ineffective.",
        "positive": "Collective photoprotection through light-induced phase separation in a\n  phototactic micro-alga: Light can be harmful for photosynthetic organisms when it exceeds the\ncapacity of photon conversion by the photosynthetic machinery. When light\nintensity is too high, the motile micro-algae Chlamydomonas reinhardtii\nreorients itself to swim away from the source. We recently discovered that a\nsuspension of photophobic algae can be unstable, occasioning a complete phase\nseparation of the system with the emergence of an active liquid phase. Indeed\nhere small spatial fluctuations in cell density influence the phototactic\nbehavior of surrounding cells which tend to join and therefore amplify the\nfluctuations. In a cylindrical geometry, this strong coupling between cell\ndensity and light fields through both negative phototaxis and light absorption\nby the individual cells led to the emergence of dynamic branching patterns\nwhose features depend on the global cell density, light intensity and medium\nviscosity. We developed a simple model based on a drift-diffusion framework\nthat finely reproduces the experimental data on the destabilization. We finally\nshowed that this active phase separation efficiently protects the individual\ncells against the negative effects of light on the integrity of the\nphotosynthetic machinery (photoinhibition of Photosystem II), demonstrating\nthat on short timescales phototaxis efficiently contributes to photoprotection\nthrough collective behaviors at the population level."
    },
    {
        "anchor": "Entropic Interactions in Suspensions of Semi-Flexible Rods: Short-Range\n  Effects of Flexibility: We compute the entropic interactions between two colloidal spheres immersed\nin a dilute suspension of semi-flexible rods. Our model treats the\nsemi-flexible rod as a bent rod at fixed angle, set by the rod contour and\npersistence lengths. The entropic forces arising from this additional\nrotational degree of freedom are captured quantitatively by the model, and\naccount for observations at short range in a recent experiment. Global fits to\nthe interaction potential data suggest the persistence length of fd-virus is\nabout two to three times smaller than the commonly used value of $2.2 \\mu {m}$.",
        "positive": "Shear-Induced Reversibility of quasi-2D Colloids in Presence of Thermal\n  Noise: The effects of thermal noise on particle rearrangements in colloidal\nsuspensions undergoing cyclic shear are experimentally investigated using\nparticle tracking methods. The experimental model system consists of\npolystyrene particles adsorbed at an oil- water interface, in which the\nparticles exhibit small but non-negligible Brownian motion. We perform\nexperiments on bidisperse (1 and 1.2 $\\mu$m in size) colloidal samples with\narea fractions ($\\phi$ ) of 0.20 and 0.32. Reversibility of particle\nrearrangements are characterized, and we show that unlike dense athermal\nsystems, reversible clusters are not stable; once a particle enters into a\nreversible trajectory, it has a nonzero probability of becoming irreversible in\nthe following shearing cycle. This probability was previously found to be\napproximately zero for an analogous athermal system. We demonstrate that the\nstability of reversibility depends both on packing fraction, $\\phi$ , and the\nshearing amplitude, $\\gamma_0$. In addition, we identify hysteresis in the\ndynamics of rearrangements for reversible particles, which indicates that such\nrearrangements are dissipative. At lower packing fractions, this hysteresis\nbecomes less prominent, and the dynamics is moved closer to equilibrium by\nthermal noise."
    },
    {
        "anchor": "Interaction between two polyelectrolytes in monovalent aqueous salt\n  solutions: We use the recently developed soft-potential-enhanced Poisson-Boltzmann (SPB)\ntheory to study the interaction between two parallel polyelectrolytes (PEs) in\nmonovalent ionic solutions in the weak-coupling regime. The SPB theory is\nfitted to ion distributions from coarse-grained molecular dynamics (MD)\nsimulations and benchmarked against all-atom MD modelling for\npoly(diallyldimethylammonium) (PDADMA). We show that the SPB theory is able to\naccurately capture the interactions between two PEs at distances beyond the PE\nradius. For PDADMA positional correlations between the charged groups lead to\nlocally asymmetric PE charge and ion distributions. This gives rise to small\ndeviations from the SPB prediction that appear as short-range oscillations in\nthe potential of mean force. Our results suggest that the SPB theory can be an\nefficient way to model interactions in chemically specific complex PE systems.",
        "positive": "Particle-based model of active skyrmions: Motivated by recent experimental results that reveal rich collective dynamics\nof thousands-to-millions of active liquid crystal skyrmions we have developed a\ncoarse grained particle-based model of the dynamics of skyrmions in dilute\nregime. The basic physical mechanism of the skyrmion motion is related to the\nnon-reciprocal rotational dynamics of the liquid crystal director field when\nthe electric field is turned {\\it on} and {\\it off}. Guided by fine grained\nresults of the Frank-Oseen continuum approach, we have mapped this\nnon-reciprocal director distortions onto an effective force acting\nasymmetrically upon switching the electrical field {\\it on} or {\\it off}. The\ncoarse grained model correctly reproduces the skyrmion dynamics, including the\nvelocity reversal as a function of the frequency of a pulse width modulated\ndriving voltage. We have also obtained approximate analytical expressions for\nthe phenomenological model parameters encoding their dependence upon the\ncholesteric pitch and the strength of the electric field. This has been\nachieved by fitting coarse grained skyrmion trajectories to those determined in\nthe framework of the Frank-Oseen model."
    },
    {
        "anchor": "Ridge approximation for thin nematic polymer networks: Nematic polymer networks (NPNs) are nematic elastomers within which the\nnematic director is enslaved to the elastic deformation. The elastic free\nenergy of a NPN sheet of thickness $h$ has both stretching and bending\ncomponents (the former scaling like h, the latter scaling like $h^3$). NPN\nsheets bear a director field $\\mathbf{m}$ imprinted in them (usually, uniformly\nthroughout their thickness); they can be activated by changing the nematic\norder (e.g. by illumination or heating). This paper illustrates an attempt to\ncompute the bending energy of a NPN sheet and to show which role it can play in\ndetermining the activated shape. Our approach is approximate: the activated\nsurface consists of flat sectors connected by ridges, where the unit normal\njumps and the bending energy is concentrated. By increasing the number of\nridges, we should get closer to the real situation, where the activated surface\nis smooth and the bending energy is distributed on it. The method is applied to\na disk with imprinted a spiraling hedgehog. It is shown that upon activation\nthe disk, like a tiny hand, is able to grab a rigid lamina.",
        "positive": "Diverging viscosity and soft granular rheology in non-Brownian\n  suspensions: We use large scale computer simulations and finite size scaling analysis to\nstudy the shear rheology of dense three-dimensional suspensions of frictionless\nnon-Brownian particles in the vicinity of the jamming transition. We perform\nsimulations of soft repulsive particles at constant shear rate, constant\npressure, and finite system size, and study carefully the asymptotic limits of\nlarge system sizes and infinitely hard particle repulsion. Extending earlier\nanalysis by about two orders of magnitude, we first study the asymptotic\nbehavior of the shear viscosity in the hard particle limit. We confirm its\nasymptotic power law divergence at the jamming transition, but show that a\nprecise determination of the critical density and critical exponent is\ndifficult due to the `multiscaling' behavior of the viscosity. Additionally,\nfinite-size scaling analysis suggests that this divergence is accompanied by a\ngrowing correlation length scale, which also diverges algebraically. We then\nstudy the effect of soft repulsion, and propose a natural extension of the\nstandard granular rheology to account for softness effects, which we validate\nfrom simulations. Close to the jamming transition, this `soft granular\nrheology' offers a detailed description of the non-linear rheology of soft\nparticles, which differs from earlier empirical scaling forms."
    },
    {
        "anchor": "Water-phospholipid interactions at the interface of lipid membranes:\n  comparison of different force fields: Water-phospholipid interactions at the lipid bilayer/water interfaces are of\nessential importance for the dynamics, stability and function of biological\nmembrane, and are also strongly associated with numerous biological processes\nat the interfaces of lipid bilayers. Various force fields, such as the\nunited-atom Berger force field, its two improved versions by Kukol and by\nPoger, and the all-atom Slipid force field developed recently, can be applied\nto simulating the structures of lipid bilayer, with their structural\npredictions in good agreement with experimental data. In this work, we show\nthat despite the similarity in structural predictions of lipid bilayers, there\nare observable differences in formation of hydrogen bonds and the interaction\nenergy profiles between water and phospholipid groups at the lipid\nbilayer/water interfaces, when four force fields for\ndipalmitoylphosphatidylcholine (DPPC) phospholipids are employed in molecular\ndynamics simulations. In particular, the Slipid force field yields more\nhydrogen bonds between water and phospholipids and more symmetrical interaction\nenergy distributions for the two carboxylic groups on their respective acyl\ntails, compared to the Berger and its two improved force fields. These\ndifferences are mainly attributed to the different interfacial water\ndistributions and ability to form hydrogen bonds between interfacial water and\noxygen atoms of the DPPC lipids using different force fields. These results\nwould be helpful in understanding the behaviors of water as well as its\ninteraction with phospholipids at the lipid bilayer/water interfaces, and\nprovide a guide for making the appropriate choice on the force field in\nsimulations of lipid bilayers.",
        "positive": "Induced Charge Anisotropy: a Hidden Variable Affecting Ion Transport\n  through Membranes: The ability of semipermeable membranes to selectively impede the transport of\nundesirable solutes is key to many applications. Yet, obtaining a systematic\nunderstanding of how membrane structure affects selectivity remains elusive due\nto the insufficient spatiotemporal resolution of existing experimental\ntechniques, and the inaccessibility of relevant solute transport timescales to\nconventional molecular simulations. Here, we utilize jumpy forward-flux\nsampling to probe the transport of sodium and chloride ions through a graphitic\nmembrane with sub-nm pores. We find chlorides to traverse the pore at rates\nover two orders of magnitude faster than sodiums. We also identify two major\nimpediments to the transport of both ion types. In addition to the partial\ndehydration of the leading ion, its traversal induces charge anisotropy at its\nrear, which exerts a net restraining force on the ion. Charge anisotropy is\ntherefore a crucial hidden variable controlling the kinetics of ion transport\nthrough nanopores."
    },
    {
        "anchor": "Structure of Multicomponent Coulomb Crystals: Coulomb plasmas crystallize in a number of physical systems, such as dusty\nplasmas, neutron star crusts, and white dwarf cores. The crystal structure of\nthe one component and binary plasma has received significant attention in the\nliterature, though the less studied multicomponent plasma may be most relevant\nfor many physical systems which contain a large range of particle charges. We\nreport on molecular dynamics simulations of multicomponent plasmas near the\nmelting temperature with mixtures taken to be realistic X-ray burst ash\ncompositions. We quantify the structure of the crystal with the bond order\nparameters and radial distribution function. Consistent with past work, low\ncharge particles form interstitial defects and we argue that they are in a\nquasi-liquid state within the lattice. The lattice shows screening effects\nwhich preserves long range order despite the large variance in particle charges\nwhich may impact transport properties relevant to astrophysics.",
        "positive": "Quantifying the efficiency of principal signal transmission modes in\n  proteins: On the microscopic level, biological signal transmission relies on\ncoordinated structural changes in allosteric proteins that involve sensor and\neffector modules. The timescales and microscopic details of signal transmission\nin proteins are often unclear, despite a plethora of structural information on\nsignaling proteins. Based on linear-response theory, we develop a theoretical\nframework to define frequency-dependent force and displacement transmit\nfunctions through proteins and, more generally, viscoelastic media. Transmit\nfunctions quantify the fraction of a local time-dependent perturbation at one\nsite, be it a deformation, a force, or a combination thereof, that survives at\na second site. They are defined in terms of equilibrium fluctuations from\nsimulations or experimental observations. We apply the framework to our\nall-atom molecular dynamics simulation data of a parallel, homodimeric\ncoiled-coil (CC) motif that connects sensor and effector modules of a\nblue-light-regulated histidine kinase from bacterial signaling systems\nextensively studied in experiments. Our analysis reveals that signal\ntransmission through the CC is possible via shift, splay, and twist deformation\nmodes. Based on the results of mutation experiments, we infer that the most\nrelevant mode for the biological function of the histidine kinase protein is\nthe splay deformation."
    },
    {
        "anchor": "Transient shear banding during startup flow: Insights from nonlinear\n  simulations: We study the dynamics of shear startup of the Johnson-Segalman and\nnon-stretching Rolie-Poly models using nonlinear simulations. We consider cases\nwhere the startup is from zero shear rate to shear rates in both the monotonic\nand nonmonotonic regions of the constitutive curve. For the Johnson-Segalman\nmodel, which exhibits a shear stress overshoot during startup, our nonlinear\nsimulations show that transient shear banding is absent regardless of whether\nthe start-up shear rate is in the monotonic or nonmonotonic regions of the\nconstitutive curve. In the latter case, while there is clearly an inhomogeneity\nen route to the banded state, the extent of shear banding is not substantially\nlarge compared to that of the eventual banded state. Marked inhomogeneity in\nthe velocity profile is predicted for the non-stretching Rolie-Poly model only\nif the solvent to solution viscosity ratio is smaller than O(10^(-3), but its\noccurrence does not appear to have any correlation with the stress overshoot\nduring startup. These inhomogeneities are also very sensitive to initial\namplitude of perturbations and the magnitude of Reynolds number. Our nonlinear\nsimulations show that the transient evolution during shear startup is quite\nsensitive to the Reynolds number when the solvent viscosity parameter is much\nsmaller than unity for non-stretching Rolie-Poly model. However, the results of\nthe Johnson-Segalman model are very robust for solvent to solution viscosity\ngreater than O(10^(-3) and do not reveal any transient shear banding during\nshear startup.",
        "positive": "Coupling Transitions in Helical Polymers: The Case of the Helix-Coil and\n  Coil-Globule Transitions: We explore the coupling between the helix-coil and coil-globule transitions\nof a helical polymer using Monte Carlo simulations. A very rich state diagram\nis found. Each state is characterized by a specific configuration of the chain\nwhich could be a helix, a random coil, an amorphous globule or one of various\nother globular states which carry residual helical strands. We study the\nboundaries between states and provide further insight into the physics of the\nsystem with a detailed analysis of the order parameter and other properties."
    },
    {
        "anchor": "New Duality Relations for Classical Ground States: We derive new duality relations that link the energy of configurations\nassociated with a class of soft pair potentials to the corresponding energy of\nthe dual (Fourier-transformed) potential. We apply them by showing how\ninformation about the classical ground states of short-ranged potentials can be\nused to draw new conclusions about the nature of the ground states of\nlong-ranged potentials and vice versa. They also lead to bounds on the T=0\nsystem energies in density intervals of phase coexistence, the identification\nof a one-dimensional system that exhibits an infinite number of ``phase\ntransitions,\" and a conjecture regarding the ground states of purely repulsive\nmonotonic potentials.",
        "positive": "Electrophoresis of metal-dielectric Janus particles with dipolar\n  director symmetry in nematic liquid crystals: We study electrophoretic mobility of metal-dielectric Janus particles with\ndipolar director profile in two nematic liquid crystals (LCs) having same\n(positive) conductivity anisotropy and opposite dielectric anisotropy. The\napplied ac electric field is parallel and perpendicular to the director for the\npositive and negative dielectric anisotropy LCs, respectively. The velocity of\nthe Janus particles in both LCs is significantly higher than that of the\nnon-Janus particles. We map the electroosmotic flow fields surrounding the\nparticles using microparticle image velocimetry ($\\mu$-PIV) and show that the\nflows on the metal hemisphere is stronger than that on the dielectric\nhemisphere and the pumping of LC along the direction of motion of the Janus\nparticles is more than that of the non-Janus particles. For a given liquid\ncrystal, particles with asymmetric surface properties is useful for enhancing\ntheir electrophoretic mobility and activity."
    },
    {
        "anchor": "Molecular Simulations of Dewetting: We have studied the breakup and subsequent fluid flow in very thin films of\npartially wetting liquid on solid substrates, using molecular dynamics\nsimulations. The liquid is made of short chain molecules interacting with\nLennard-Jones interactions, and the solid is modeled as a clean crystal lattice\nwhose atoms have thermal oscillations. Films below a critical thickness are\nfound to exhibit a spontaneous spinodal-like instability leading to dry\npatches, as predicted theoretically and observed in some experiments. Liquid\nwithdrawing from a dry patch collects in a moving rim whose fluid dynamics is\nonly partially in agreement with earlier predictions.",
        "positive": "A polymer-based technique to remove pollutants from soft contact lenses: Purpose: To demonstrate an alternative to the rinse and rub (RR) method for\ncleaning pollutants from the exterior surface of soft contact lenses. This\nproposed technique is termed Polymer on Polymer Pollutant Removal (PoPPR),\nwhich utilizes the elastic properties of polydimethylsiloxane (PDMS) to\nphysically remove contaminants from contact lens surfaces through non-adhesive\nunpeeling.\n  Methods: Three different ratios of setting agent to polymer PDMS (1:30, 1:40,\nand 1:50) were evaluated using the PoPPR method against the control method of\nRR with a commercial multi-purpose lens cleaning solution. Three simulated\npollutants of different sizes: pollen (25-40 {\\mu}m), microbeads (1-5 {\\mu}m),\nand nanoparticles (5-10 nm), were used to test the effectiveness of both\ncleaning methods. The fraction of pollutants removed from each contact lens was\nrecorded and evaluated for significance.\n  Results: PDMS 1:40 was found to be the optimal ratio for lens cleaning using\nthe PoPPR method. For larger particles (>10 {\\mu}m), no difference was observed\nbetween conventional RR and proposed PoPPR method (p > 0.05). However, the new\nPoPPR technique was significantly better at removing small PM2.5 particles\n(<2.5 {\\mu}m) compared to the RR method, specifically for microbeads (p =\n0.006) and nanoparticles (p < 0.001).\n  Conclusion: This proof-of-concept work demonstrates that the PoPPR method of\ncleaning contact lenses is as effective as the conventional cleaning method for\nlarger particles such as pollen. The PoPPR method is more effective at removing\nextremely fine particulate pollutants, including microplastics and\nnanoparticles. This method offers a potentially more efficient cleaning\nprotocol that could enhance the safety, health, and comfort of contact lens\nusers, especially those living in regions with significant air pollution."
    },
    {
        "anchor": "Free Energy Landscape of a Protein-Like Chain in a Fluid with\n  Discontinuous Potentials: The free energy landscape of a protein-like chain in a fluid was studied by\ncombining discontinuous molecular dynamics and parallel tempering. The model\nprotein is a repeating sequence of four different beads, with interactions\nmimicking those in real proteins. Neighbor distances and angles are restricted\nto physical ranges and one out of the four kinds of beads can form hydrogen\nbonds with each other, except if they are too close in the chain. In contrast\nto earlier studies of this model, an explicit square-well solvent is included.\nBeads that can form intra-chain hydrogen bonds, can also form (weaker) hydrogen\nbonds with solvent molecules, while other beads are insoluble. By categorizing\nthe protein configurations according to their intra-chain bonds, one can\ndistinguish unfolded, helical, and collapsed helical structures. Simulations\nfor chains of 15, 20 and 25 beads show that at low temperatures, the most\nlikely structures are helical or collapsed helical, despite the low entropy of\nthese structures. The temperature at which helical structures become dominant\nis higher than in the absence of a solvent. The cooperative effect of the\nsolvent is attributed to the presence of hydrophobic beads. A phase transition\nof the solvent prevented the simulations of the 20-bead and 25-bead chains of\nreaching low enough temperatures to confirm whether the free energy landscape\nis funnel-shaped, although the results do not contradict that possibility.",
        "positive": "On the replica scenario for the glass transition: In this letter we study a lattice gas system that undergoes a glassy\ntransition. When we approach the glass transition we find both a divergence of\na point to set correlation length and the vanishing of the thermodynamic\npotential. These findings are similar to the predictions coming from mean-field\n(replica) theory, but they differ from these predictions in some details: they\nunderline the need of a better theoretical understanding of the glassy\ntransition."
    },
    {
        "anchor": "Numerical study of DNA denaturation with self-avoidance: pseudo-critical\n  temperatures and finite size behaviour: We perform an extensive numerical study of the disordered Poland-Scheraga\n(PS) model for DNA denaturation in which self-avoidance is completely taken\ninto account. In complement to our previous work, we focus here on the finite\nsize scaling in terms of pseudo-critical temperatures. We find notably that the\nmean value and the fluctuations of the pseudo-$T_c$ scale with the same\nexponent, the correlation length exponent $\\nu_r$ (for which we provide the\nrefined evaluation $\\nu_r=2.9 \\pm 0.4$). This result (coherent with the typical\npicture that describes random ferromagnets, when disorder is relevant) is at\nvariance with numerical results reported in the literature for the PS model\nwith self-avoidance, leading to an alternative scenario with a pseudo first\norder transition. We moreover introduce a crossover chain length $N^*$, which\nwe evaluate, appropriate for characterizing the approach to the asymptotic\nregime in this model. Essentially, below $N^*$, the behaviour of the model in\nour study could also agree with such alternative scenario. Based on an\napproximate prediction of the dependence of $N^*$ on the parameters of the\nmodel, we show that following the choice of such parameters it could be not\npossible to reach the asymptotic regime in practice. In such context it becomes\nthen possible to reconcile the apparently contradictory numerical studies.",
        "positive": "Stratification of drying particle suspensions: Comparison of implicit\n  and explicit solvent simulations: Large scale molecular dynamics simulations are used to study drying\nsuspensions of a binary mixture of large and small particles in explicit and\nimplicit solvents. The solvent is first modeled explicitly and then mapped to a\nuniform viscous medium by matching the diffusion coefficients and the pair\ncorrelation functions of the particles. `Small-on-top' stratification of the\nparticles, with an enrichment of the smaller ones at the receding liquid-vapor\ninterface during drying, is observed in both models under the same drying\nconditions. With the implicit solvent model, we are able to model much thicker\nfilms and study the effect of the initial film thickness on the final\ndistribution of particles in the dry film. Our results show that the degree of\nstratification is controlled by the P\\'{e}clet number defined using the initial\nfilm thickness as the characteristic length scale. When the P\\'{e}clet numbers\nof large and small particles are much larger than 1, the degree of\n`small-on-top' stratification is first enhanced and then weakens as the\nP\\'{e}clet numbers are increased."
    },
    {
        "anchor": "Ferroelectric chiral nematic liquid crystals: New photonic materials\n  with multiple bandgaps controllable by low electric fields: We have carried out a spectroscopic study on a prototype ferroelectric\nnematic material (RM7343) doped with a non-polar chiral compound. The mixture\npresents two chiral nematic phases, one conventional (N*) and the other polar\n(NF*), whose behaviours under electric fields E are totally different. On the\none hand, the N* phase shows a single reflection band if E is not very high,\nwhile fields perpendicular to the helix of a few V/mm are already sufficient to\nproduce multiple bands in the NF* phase. On the other hand, the pitch of the\nNF* phase grows notably on increasing fields, however remaining practically\nconstant in the N* phase. Both effects have been explained in terms of the\ndifferent type of interaction with E in each phase (ferroelectric in NF* and\ndielectric in N*). We argue that the NF* phase behaves as a photonic material\nwith multiple gaps tunable by small fields, which presents important\npotentialities for applications. A study of the bandgaps has been carried out\nthrough the analysis of the dispersion relation of the optical eigenmodes in\nthe NF* phase under field. Finally, an example of the potentialities of the NF*\nphase within the field of nonlinear optics is briefly presented.",
        "positive": "A Simple Computer Model for Liquid Lipid Bilayers: We present a simple coarse-grained bead-and-spring model for lipid bilayers.\nThe system has been developed to reproduce the main (gel-liquid) transition of\nbiological membranes on intermediate length scales of a couple of nanometres\nand is very efficient from a computational point of view. For the solvent\nenvironment, two different models are proposed. The first model forces the\nlipids to form bilayers by confining their heads in two parallel planes. In the\nsecond model, the bilayer is stabilised by a surrounding gas of \"phantom\"\nsolvent beads, which do not interact with each other. This model takes only\nslightly more computing time than the first one, while retaining the full\nmembrane flexibility. We calculate the liquid-gel phase boundaries for both\nmodels and find that they are very similar."
    },
    {
        "anchor": "Confinement effects on diffusiophoretic self-propellers: We study theoretically the effects of spatial confinement on the phoretic\nmotion of a dissolved particle driven by composition gradients generated by\nchemical reactions of its solvent, which are active only on certain parts of\nthe particle surface. We show that the presence of confining walls increases in\na similar way both the composition gradients and the viscous friction, and the\noverall result of these competing effects is an increase in the phoretic\nvelocity of the particle. For the case of steric repulsion only between the\nparticle and the product molecules of the chemical reactions, the absolute\nvalue of the velocity remains nonetheless rather small.",
        "positive": "Probing shells against buckling: a non-destructive technique for\n  laboratory testing: This paper addresses testing of compressed structures, such as shells, that\nexhibit catastrophic buckling and notorious imperfection sensitivity. The\ncentral concept is the probing of a loaded structural specimen by a controlled\nlateral displacement to gain quantitative insight into its buckling behaviour\nand to measure the energy barrier against buckling. This can provide design\ninformation about a structure's stiffness and robustness against buckling in\nterms of energy and force landscapes. Developments in this area are relatively\nnew but have proceeded rapidly with encouraging progress. Recent experimental\ntests on uniformly compressed spherical shells, and axially loaded cylinders,\nshow excellent agreement with theoretical solutions. The probing technique\ncould be a valuable experimental procedure for testing prototype structures,\nbut before it can be used a range of potential problems must be examined and\nsolved. The probing response is highly nonlinear and a variety of complications\ncan occur. Here, we make a careful assessment of unexpected limit points and\nbifurcations, that could accompany probing, causing complications and possibly\neven collapse of a test specimen. First, a limit point in the probe\ndisplacement (associated with a cusp instability and fold) can result in\ndynamic buckling as probing progresses, as demonstrated in the buckling of a\nspherical shell under volume control. Second, various types of bifurcations\nwhich can occur on the probing path which result in the probing response\nbecoming unstable are also discussed. To overcome these problems, we outline\nthe extra controls over the entire structure that may be needed to stabilize\nthe response."
    },
    {
        "anchor": "Low-energy quasilocalized excitations in structural glasses: Glassy solids exhibit a wide variety of generic thermomechanical properties,\nranging from universal anomalous specific heat at cryogenic temperatures to\nnonlinear plastic yielding and failure under external driving forces, which\nqualitatively differ from their crystalline counterparts. For a long time, it\nhas been believed that many of these properties are intimately related to\nnonphononic, low-energy quasilocalized excitations (QLEs) in glasses. Indeed,\nrecent computer simulations have conclusively revealed that the\nself-organization of glasses during vitrification upon cooling from a melt\nleads to the emergence of such QLEs. In this Perspective Article, we review\ndevelopments over the past three decades towards understanding the emergence of\nQLEs in structural glasses, and the degree of universality in their statistical\nand structural properties. We discuss the challenges and difficulties that\nhindered progress in achieving these goals, and review the frameworks put\nforward to overcome them. We conclude with an outlook on future research\ndirections and open questions.",
        "positive": "Confined nanorods: jamming due to helical buckling: We investigate a longitudinally loaded elastic nanorod inside a cylindrical\nchannel and show within the context of classical elasticity theory that the\nEuler buckling instability leads to a helical postbuckling form of the rod\nwithin the channel. The local pitch of the confined helix changes along the\nchannel and so does the longitudinal force transmitted along the rod,\ndiminishing away from the loaded end. This creates a possibility of jamming of\nthe nanorod within the channel."
    },
    {
        "anchor": "Microstructure-enabled control of wrinkling in nematic elastomer sheets: Nematic elastomers are rubbery solids which have liquid crystals incorporated\ninto their polymer chains. These materials display many unusual mechanical\nproperties, one such being the ability to form fine-scale microstructure. In\nthis work, we explore the response of taut and appreciably stressed sheets made\nof nematic elastomer. Such sheets feature two potential instabilities -- the\nformation of fine-scale material microstructure and the formation of fine-scale\nwrinkles. We develop a theoretical framework to study these sheets that\naccounts for both instabilities, and we implement this framework numerically.\nSpecifically, we show that these instabilities occur for distinct mesoscale\nstretches, and observe that microstructure is finer than wrinkles for\nphysically relevant parameters. Therefore, we relax (i.e., implicitly but\nrigorously account for) the microstructure while we regularize (i.e., compute\nthe details explicitly) the wrinkles. Using both analytical and numerical\nstudies, we show that nematic elastomer sheets can suppress wrinkling by\nmodifying the expected state of stress through the formation of microstructure.",
        "positive": "Molecular scale contact line hydrodynamics of immiscible flows: From extensive molecular dynamics simulations on immiscible two-phase flows,\nwe find the relative slipping between the fluids and the solid wall everywhere\nto follow the generalized Navier boundary condition, in which the amount of\nslipping is proportional to the sum of tangential viscous stress and the\nuncompensated Young stress. The latter arises from the deviation of the\nfluid-fluid interface from its static configuration. We give a continuum\nformulation of the immiscible flow hydrodynamics, comprising the generalized\nNavier boundary condition, the Navier-Stokes equation, and the Cahn-Hilliard\ninterfacial free energy. Our hydrodynamic model yields interfacial and velocity\nprofiles matching those from the molecular dynamics simulations at the\nmolecular-scale vicinity of the contact line. In particular, the behavior at\nhigh capillary numbers, leading to the breakup of the fluid-fluid interface, is\naccurately predicted."
    },
    {
        "anchor": "Slider on a Driven Substrate: Markovian Competition Between Two Limiting\n  Attractors: We present experimental data of the motion of a rimmed checker's piece on a\npolished horizontal tray, in two specific conditions: with the substrate\nharmonically shaken at 20 Hz, and with a static substrate. The latter\nexperiment immediately yields the dynamic friction coefficient. The harmonic\nexperimental results are very sensitive on the static friction coefficient,\nwhich is not even a percent higher than the dynamic one. Due to the low\nharmonic acceleration of the driver, the static friction has enormous influence\non the slider's motion. We modeled the slider's motion using a discrete\nMarkovian progression model, which at every discrete time-step chooses between\na sticking attempt and a return to the non-sticking trajectory. The present\nmodel does not take into account the driver's acceleration. In the final\nsection, we explain the physical origin of walk-off, in case of periodic but\nasymmetric driving.",
        "positive": "Gel and glass transition in fragile colloidal clays: Dynamic Light Scattering (DLS) measurements were performed on colloidal\nsuspensions of Laponite\\textsuperscript{\\textregistered} at different\nconcentrations in the range $C_\\text{w}= (1.5{\\div}3.0)$%. The slowing down of\nthe dynamics induced by aging was monitored by following the temporal evolution\nof autocorrelation functions at different concentrations towards the gel and\nglass transition. Exploiting analogies with supercooled liquids approaching\ntheir glass transitions, an Angell plot for the structural relaxation times was\ndrawn. Finally, the fragility of Laponite\\textsuperscript{\\textregistered}\nsuspensions at different concentrations, in different solvents, at two salt\nconcentrations and with the addition of a polymer was reported and discussed."
    },
    {
        "anchor": "Test of a simple and flexible molecule model for alpha-, beta- and\n  gamma-S8 crystals: S8 is the most stable compound of elemental sulfur in solid and liquid\nphases, at ambient pressure and below 400K. Three crystalline phases of S8 have\nbeen clearly identified in this range of thermodynamic parameters, although no\ncalculation of its phase diagram has been performed yet. alpha- and gamma-S8\nare orientationally ordered crystals while beta-S8 is measured as\norientationally disordered. In this paper we analyze the phase diagram of S8\ncrystals, as given by a simple and flexible molecule model, via a series of\nmolecular dynamics (MD) simulations.\n  The calculations are performed in the constant pressure- constant temperature\nensemble, using an algorithm that is able to reproduce structural phase\ntransitions.",
        "positive": "Diffusion NMR study of complex formation in membrane-associated peptides: Pulsed-field-gradient nuclear magnetic resonance (PFG-NMR) is used to obtain\nthe true hydrodynamic size of complexes of peptides with sodium dodecyl sulfate\nSDS micelles. The peptide used in this study is a 19-residue antimicrobial\npeptide, GAD-2. Two smaller dipeptides, alanine-glycine (Ala-Gly) and\ntyrosine-leucine (Tyr-Leu), are used for comparison. We use PFG-NMR to\nsimultaneously measure diffusion coefficients of both peptide and surfactant.\nThese two inputs, as a function of SDS concentration, are then fit to a simple\ntwo species model that neglects hydrodynamic interactions between complexes.\nFrom this we obtain the fraction of free SDS, and the hydrodynamic size of\ncomplexes in a GAD-2--SDS system as a function of SDS concentration. These\nresults are compared to those for smaller dipeptides and for peptide-free\nsolutions. At low SDS concentrations ([SDS] $\\leq$ 25 mM), the results\nself-consistently point to a GAD-2--SDS complex of fixed hydrodynamic size R\n=(5.5 $\\pm$ 0.3) nm. At intermediate SDS concentrations (25 mM $<$ [SDS] $<$ 60\nmM), the apparent size of a GAD-2--SDS complex shows almost a factor of two\nincrease without a significant change in surfactant-to-peptide ratio within a\ncomplex, most likely implying an increase in the number of peptides in a\ncomplex. For peptide-free solutions, the self-diffusion coefficients of SDS\nwith and without buffer are significantly different at low SDS concentrations\nbut merge above [SDS]=60 mM. We find that in order to obtain unambiguous\ninformation about the hydrodynamic size of a peptide-surfactant complex from\ndiffusion measurements, experiments must be carried out at or below [SDS] = 25\nmM."
    },
    {
        "anchor": "Factors influencing thermal solidification of bent-core trimers: Bent-core trimers are a simple model system for which the competition between\ncrystallization and glass-formation can be tuned by varying a single\nparameter:\\ the bond angle $\\theta_0$. Using molecular dynamics simulations, we\nexamine how varying $\\theta_0$ affects their thermal solidification. By\nexamining trends with $\\theta_0$, comparing these to trends in trimers' jamming\nphenomenology, and then focusing on the six $\\theta_0$ that are commensurable\nwith close-packed crystalline order, we obtain three key results: \\textbf{(i)}\nthe increase in trimers' solidification temperature $T_s(\\theta_0)$ as they\nstraighten (as $\\theta_0 \\to 0^\\circ$) is driven by the same gradual loss of\n\\textit{effective} configurational freedom that drives athermal trimers'\ndecreasing $\\phi_J(\\theta_0)$; \\textbf{(ii)} $\\theta_0$ that allow formation of\nboth FCC and HCP order crystallize, while $\\theta_0$ that only allow formation\nof HCP order glass-form; \\textbf{(iii)} local cluster-level structure at\ntemperatures slightly \\textit{above} $T_s(\\theta_0)$ is highly predictive of\nwhether trimers will crystallize or glass-form.",
        "positive": "Thermodynamic interpretation of the scaling of the dynamics of\n  supercooled liquids: The recently discovered scaling law for the relaxation times, tau=f(T,V^g),\nwhere T is temperature and V the specific volume, is derived by a revision of\nthe entropy model of the glass transition dynamics originally proposed by\nAvramov [I. Avramov, J. Non-Cryst. Solids 262, 258 (2000).]. In this\nmodification the entropy is calculated by an alternative route, while retaining\nthe approximation that the heat capacity is constant with T and P. The\nresulting expression for the variation of the relaxation time with T and V is\nshown to accurately fit experimental data for several glass-forming liquids and\npolymers over an extended range encompassing the dynamic crossover. From this\nanalysis, which is valid for any model in which the relaxation time is a\nfunction of the entropy. we find that the scaling exponent g can be identified\nwith the Gruneisen constant."
    },
    {
        "anchor": "Coarse-grained modelling of DNA-RNA hybrids: We introduce oxNA, a new model for the simulation of DNA-RNA hybrids which is\nbased on two previously developed coarse-grained models$\\unicode{x2014}$oxDNA\nand oxRNA. The model naturally reproduces the physical properties of hybrid\nduplexes including their structure, persistence length and force-extension\ncharacteristics. By parameterising the DNA-RNA hydrogen bonding interaction we\nfit the model's thermodynamic properties to experimental data using both\naverage-sequence and sequence-dependent parameters. To demonstrate the model's\napplicability we provide three examples of its use$\\unicode{x2014}$calculating\nthe free energy profiles of hybrid strand displacement reactions, studying the\nresolution of a short R-loop and simulating RNA-scaffolded wireframe origami.",
        "positive": "Unconventionally Fast Transport through Sliding Dynamics of Rodlike\n  Particles in Macromolecular Networks: Transport of rodlike particles in confinement environments of macromolecular\nnetworks plays crucial roles in many important biological processes and\ntechnological applications. The relevant understanding has been limited to thin\nrods with diameter much smaller than network mesh size, although the opposite\ncase, of which the dynamical behaviors and underlying physical mechanisms\nremain unclear, is ubiquitous. Here, we solve this issue by combining\nexperiments, simulations and theory. We find a nonmonotonic dependence of\ntranslational diffusion on rod length, characterized by length\ncommensuration-governed unconventionally fast dynamics which is in striking\ncontrast to the monotonic dependence for thin rods. Our results clarify that\nsuch a fast diffusion of thick rods with length of integral multiple of mesh\nsize follows sliding dynamics and demonstrate it to be \"anomalous yet\nBrownian\". Moreover, good agreement between theoretical analysis and\nsimulations corroborates that the sliding dynamics is an intermediate regime\nbetween hopping and Brownian dynamics, and provides a mechanistic\ninterpretation based on the rod-length dependent entropic free energy barrier.\nThe findings yield a principle, that is, length commensuration, for optimal\ndesign of rodlike particles with highly efficient transport in confined\nenvironments of macromolecular networks, and might enrich the physics of the\ndiffusion dynamics in heterogeneous media."
    },
    {
        "anchor": "Surface Tension and the Cosmological Constant: The astronomically observed value of the cosmological constant is small but\nnon-zero. This raises two questions together known as the cosmological constant\nproblem a) why is lambda so nearly zero? b) why is lambda not EXACTLY zero?\nSorkin has proposed that b) can be naturally explained as a one by square root\nN fluctuation by invoking discreteness of spacetime at the Planck scale due to\nquantum gravity. In this paper we shed light on these questions by developing\nan analogy between the cosmological constant and the surface tension of\nmembranes. The ``cosmological constant problem'' has a natural analogue in the\nmembrane context: the vanishingly small surface tension of fluid membranes\nprovides an example where question a) above arises and is answered. We go on to\nfind a direct analogue of Sorkin's proposal for answering question b) in the\nmembrane context, where the discreteness of spacetime translates into the\nmolecular structure of matter. We propose analogue experiments to probe a small\nand fluctuating surface tension in fluid membranes. A counterpart of\ndimensional reduction a la Kaluza-Klein and large extra dimensions also appears\nin the physics of fluid membranes.",
        "positive": "Second Blows in the Head-on Collisions of the Spherical Nano Polymer\n  Droplets: We report observations of weird but interesting phenomenon from the molecular\ndynamics simulations, occurrence of second blows in the head-on collisions of\ntwo equal-sized spherical nano polymer droplets. In the head-on collisions, we\nusually expect a single peak of impact forces between two colliding droplets.\nBut, in the simulations, the second peak of the impact forces is actually\nobserved. Its underlying mechanisms at the molecular scale are also proposed."
    },
    {
        "anchor": "Mechanics of axisymmetric sheets of interlocking and slidable rods: In this work, we study the mechanics of metamaterial sheets inspired by the\npellicle of Euglenids. They are composed of interlocking elastic rods which can\nfreely slide along their edges. We characterize the kinematics and the\nmechanics of these structures using the special Cosserat theory of rods and by\nassuming axisymmetric deformations of the tubular assembly. Through an\nasymptotic expansion, we investigate both structures that comprise a discrete\nnumber of rods and the limit case of a sheet composed by infinitely many rods.\nWe apply our theoretical framework to investigate the stability of these\nstructures in the presence of an axial load. Through a linear analysis, we\ncompute the critical buckling force for both the discrete and the continuous\ncase. For the latter, we also perform a numerical post-buckling analysis,\nstudying the non-linear evolution of the bifurcation through finite elements\nsimulations.",
        "positive": "Magnetization Distribution in the layered CMR Manganite La1.2Sr1.8Mn2O7\n  from Polarized Neutron Diffraction: In the ferromagnetic metallic state of the colossal magnetoresistive (CMR)\nmanganite La1.2Sr1.8Mn2O7, the spin density distribution is essentially in\nagreement with the standard picture in which the unpaired electrons occupy the\nthree t2g orbitals, dxy, dyz, and dxz. However we find a small spin density ~4%\nof the total Mn spin) on the apical O(2) oxygen atom at both 100 K and 220 K\nand we suggest that this is due to covalency effects. Surprisingly we find no\nevidence of spin on the other apical oxygen O(1) suggesting that the Mn eg\nelectron distribution along the c-axis is highly anisotropic."
    },
    {
        "anchor": "Structural dynamics and optimal transport of an active polymer: We study the spontaneous configuration transitions of an active semi-flexible\npolymer between spiral and non-spiral states, and show that the configuration\ndynamics is fully described by a subcritical pitchfork bifurcation. Exploiting\nthe fact that active polymer barely moves in spiral states and exhibits net\ndisplacements in non-spira states, we prove that the motion of the active\npolymer is consistent with a run-and-tumble-like dynamics. Moreover, we find\nthat there exists an optimal self-propelling force, at which the probabilities\nof finding the polymer in the spiral and non-spiral state become equal, that\nmaximizes the diffusion coefficient.",
        "positive": "Long-range translational order and hyperuniformity in two-dimensional\n  chiral active crystal: We numerically study two-dimensional athermal chiral active particles at high\ndensities. The particles in this system perform the circular motion with\nfrequency $\\Omega$. The system is known to undergo a nonequilibrium transition\nfrom the absorbing phase to the diffusing fluid phase that is accompanied by\nthe suppression of density fluctuations called hyperuniformity [Q.-L. Lei et\nal., Sci. Adv. 5, eaau7423 (2019)]. We show that the system in the fluid phase\ncrystallizes with increasing density. Surprisingly, the resulting crystal\npossesses long-range translational order even in two dimensions due to the\nsuppression of the long-wavelength displacement fluctuations associated with\nhyperuniformity. We also find that $\\Omega = 0$ is singular, and the system\nnever crystallizes because, in this limit, the system can be regarded as a\nquenched random system for which the lower critical dimension is known to be\n$4$. Our numerical results are quantitatively explained by a linear elastic\ntheory."
    },
    {
        "anchor": "Cuddling Ellipsoids: Densest local structures of uniaxial ellipsoids: Connecting the collective behavior of disordered systems with local structure\non the particle scale is an important challenge, for example in granular and\nglassy systems. Compounding complexity, in many scientific and industrial\napplications, particles are polydisperse, aspherical or even of varying shape.\nHere, we investigate a generalization of the classical kissing problem in order\nto understand the local building blocks of packings of aspherical grains. We\nnumerically determine the densest local structures of uniaxial ellipsoids by\nminimizing the Set Voronoi cell volume around a given particle. Depending on\nthe particle aspect ratio, different local structures are observed and\nclassified by symmetry and Voronoi coordination number. In extended disordered\npackings of frictionless particles, knowledge of the densest structures allows\nto rescale the Voronoi volume distributions onto the single-parameter family of\n$k$-Gamma distributions. Moreover, we find that approximate icosahedral\nclusters are found in random packings, while the optimal local structures for\nmore aspherical particles are not formed.",
        "positive": "Non-reciprocal topological solitons: From protein motifs to black holes, topological solitons are pervasive\nnonlinear excitations that are robust and that can be driven by external\nfields. So far, existing driving mechanisms all accelerate solitons and\nantisolitons towards opposite directions. Here we introduce a local driving\nmechanism for solitons that accelerates both solitons and antisolitons in the\nsame direction instead: non-reciprocal driving. To realize this mechanism, we\nconstruct an active mechanical metamaterial consisting of non-reciprocally\ncoupled oscillators subject to a bistable potential. We find that such\nnonlinearity coaxes non-reciprocal excitations -- so-called non-Hermitian skin\nwaves, which are typically unstable -- into robust oneway (anti)solitons. We\nrationalize our observations by introducing non-reciprocal generalizations of\nthe Frenkel-Kontorova and sine-Gordon models, and use the latter to predict the\nterminal velocity of the (anti)solitons and determine their stability. Finally,\nwe harness non-reciprocal topological solitons by constructing an active\nwaveguide capable of transmitting and filtering unidirectional information.\nMore broadly, our findings suggest that non-reciprocal driving is a robust\nmechanism to steer nonlinear waves and could be generalized beyond mechanics,\ne.g. quantum mechanics, optics and soft matter."
    },
    {
        "anchor": "Playing with Marbles: Structural and Thermodynamic Properties of\n  Hard-Sphere Systems: These lecture notes present an overview of equilibrium statistical mechanics\nof classical fluids, with special applications to the structural and\nthermodynamic properties of systems made of particles interacting via the\nhard-sphere potential or closely related model potentials. The exact\nstatistical-mechanical properties of one-dimensional systems, the issue of\nthermodynamic (in)consistency among different routes in the context of several\napproximate theories, and the construction of analytical or semi-analytical\napproximations for the structural properties are also addressed.",
        "positive": "A Bounded Rational Driver Model: This paper introduces a car following model where the driving scheme takes\ninto account the deficiencies of human decision making in a general way.\nAditionally, it improves certain shortcomings of most of the models currently\nin use: it is stochastic but has a continuous acceleration. This is achieved at\nthe cost of formulating the model in terms of the time derivative of the\nacceleration, making it non-Newtonian."
    },
    {
        "anchor": "Molecular diffusion and slip boundary conditions at smooth surfaces with\n  periodic and random nanoscale textures: The influence of periodic and random surface textures on the flow structure\nand effective slip length in Newtonian fluids is investigated by molecular\ndynamics (MD) simulations. We consider a situation where the typical pattern\nsize is smaller than the channel height and the local boundary conditions at\nwetting and nonwetting regions are characterized by finite slip lengths. In\ncase of anisotropic patterns, transverse flow profiles are reported for flows\nover alternating stripes of different wettability when the shear flow direction\nis misaligned with respect to the stripe orientation. The angular dependence of\nthe effective slip length obtained from MD simulations is in good agreement\nwith hydrodynamic predictions provided that the stripe width is larger than\nseveral molecular diameters. We found that the longitudinal component of the\nslip velocity along the shear flow direction is proportional to the interfacial\ndiffusion coefficient of fluid monomers in that direction at equilibrium. In\ncase of random textures, the effective slip length and the diffusion\ncoefficient of fluid monomers in the first layer near the heterogeneous surface\ndepend sensitively on the total area of wetting regions.",
        "positive": "Application of Self-Consistent Field Theory to Self-Assembled Bilayer\n  Membranes: Bilayer membranes self-assembled from amphiphilic molecules such as lipids,\nsurfactants and block copolymers are ubiquitous in biological and\nphysiochemical systems. The shape and structure of bilayer membranes depend\ncrucially on their mechanical properties such surface tension, bending moduli\nand line tension. Understanding how the molecular property of the amphiphiles\ndetermine the structure and mechanics of the self-assembled bilayers requires a\nmolecularly detailed theoretical framework. The self-consistent field theory\nprovides such a theoretical framework, which is capable of accurately\npredicting mechanical parameters of self-assembled bilayer membranes. In this\nmini review we summarize the formulation of the self-consistent field theory,\nas exemplified by a model system composed of flexible amphiphilic chains\ndissolved in hydrophilic polymeric solvents, and its application to the study\nof self-assembled bilayer membranes."
    },
    {
        "anchor": "Challenges of interpreting dielectric dilatometry for the study of\n  pressure densification: We report an experimental study documenting the challenge of employing\ndielectric dilatometry for the study of pressure densification in glass-forming\nmaterials. An influence of the dielectric cell geometry on the resulting\ncapacitance of 5-poly-phenyl-ether upon vitrification under different\nthermobaric pathways is documented. The capacitive response is studied for two\ndifferent multilayer capacitors: one with, in principle, fixed plate distance\nand one with Kapton spacers allowing for contraction/expansion. A combination\nof changes in the dielectric permittivity of the material and modifications of\nthe capacitor geometry determines the final capacitance. We conclude that, in\norder to convert the measured capacitance to material density, it is of\nparamount importance to understand the geometry. The data presented do not make\nit possible to conclude on whether or not simple glass formers such as\n5-poly-phenyl-ether can be pressure densified, but our work highlights the\nchallenge of utilizing dielectric spectroscopy to tackle this problem\neffectively.",
        "positive": "Force distribution in a scalar model for non-cohesive granular material: We study a scalar lattice model for inter-grain forces in static,\nnon-cohesive, granular materials, obtaining two primary results. (i) The\napplied stress as a function of overall strain shows a power law dependence\nwith a nontrivial exponent, which moreover varies with system geometry. (ii)\nProbability distributions for forces on individual grains appear Gaussian at\nall stages of compression, showing no evidence of exponential tails. With\nregard to both results, we identify correlations responsible for deviations\nfrom previously suggested theories."
    },
    {
        "anchor": "Four-contact impedance spectroscopy of conductive liquid samples: We present an improved approach to the impedance spectroscopy of conductive\nliquid samples using four-electrode measurements. Our method enables impedance\nmeasurements of conductive liquids down to the sub-Hertz frequencies, avoiding\nthe electrode polarization effects that usually cripple standard impedance\nanalysers. We have successfully tested our apparatus with aqueous solutions of\npotassium chloride and gelatin. The first substance has shown flat spectra from\n$\\sim$100 kHz down to sub-Hz range, while the results on gelatin clearly show\nthe existence of two distinct low frequency conductive relaxations.",
        "positive": "Abrupt grain boundary melting in ice: The effect of impurities on the grain boundary melting of ice is investigated\nthrough an extension of Derjaguin-Landau-Verwey-Overbeek theory, in which we\ninclude retarded potential effects in a calculation of the full frequency\ndependent van der Waals and Coulombic interactions within a grain boundary. At\nhigh dopant concentrations the classical solutal effect dominates the melting\nbehavior. However, depending on the amount of impurity and the surface charge\ndensity, as temperature decreases, the attractive tail of the dispersion force\ninteraction begins to compete effectively with the repulsive screened Coulomb\ninteraction. This leads to a film-thickness/temperature curve that changes\ndepending on the relative strengths of these interactions and exhibits a\ndecrease in the film thickness with increasing impurity level. More striking is\nthe fact that at very large film thicknesses, the repulsive Coulomb interaction\ncan be effectively screened leading to an abrupt reduction to zero film\nthickness."
    },
    {
        "anchor": "A simple catch: thermal fluctuations enable hydrodynamic trapping of\n  microrollers by obstacles: It is known that obstacles can hydrodynamically trap bacteria and synthetic\nmicroswimmers in orbits, where the trapping time heavily depends on the swimmer\nflow field and noise is needed to escape the trap. Here, we use experiments and\nsimulations to investigate the trapping of microrollers by obstacles.\nMicrorollers are rotating particles close to a bottom surface, which have a\nprescribed propulsion direction imposed by an external rotating magnetic field.\nThe flow field that drives their motion is quite different from previously\nstudied swimmers. We found that the trapping time can be controlled by\nmodifying the obstacle size or the colloid-obstacle repulsive potential. We\ndetail the mechanisms of the trapping and find two remarkable features: The\nmicroroller is confined in the wake of the obstacle, and it can only enter the\ntrap with Brownian motion. While noise is usually needed to escape traps in\ndynamical systems, here, we show that it is the only means to reach the\nhydrodynamic attractor.",
        "positive": "Mixing and segregation rates in sheared granular materials: The size-segregation of granular materials, a process colloquially known as\nthe Brazil Nut Effect, has generally been thought to proceed faster the greater\nthe size difference of the particles. We experimentally investigate sheared\nbidisperse granular materials as a function of the size ratio of the two\nspecies, and find that the mixing rate at low confining pressure behaves as\nexpected from percolation-based arguments. However, we also observe an\nanomalous effect for the re-segregation rates, wherein particles of both\ndissimilar and similar sizes segregate more slowly than intermediate particle\nsize ratios. Combined with the fact that increasing the confining pressure\nsignificantly suppresses both mixing and segregation rates of particles of\ndissimilar size, we propose that the anomalous behavior may be attributed to a\nspecies-dependent distribution of forces within the system."
    },
    {
        "anchor": "Random Scalar Fields and Hyperuniformity: Disordered many-particle hyperuniform systems are exotic amorphous states of\nmatter that lie between crystals and liquids. Hyperuniform systems have\nattracted recent attention because they are endowed with novel transport and\noptical properties. Recently, the hyperuniformity concept has been generalized\nto characterize scalar fields, two-phase media and random vector fields. In\nthis paper, we devise methods to explicitly construct hyperuniform scalar\nfields. We investigate explicitly spatial patterns generated from Gaussian\nrandom fields, which have been used to model the microwave background radiation\nand heterogeneous materials, the Cahn-Hilliard equation for spinodal\ndecomposition, and Swift-Hohenberg equations that have been used to model\nemergent pattern formation, including Rayleigh-B{\\' e}nard convection. We show\nthat the Gaussian random scalar fields can be constructed to be hyperuniform.\nWe also numerically study the time evolution of spinodal decomposition patterns\nand demonstrate that these patterns are hyperuniform in the scaling regime.\nMoreover, we find that labyrinth-like patterns generated by the Swift-Hohenberg\nequation are effectively hyperuniform. We show that thresholding a hyperuniform\nGaussian random field to produce a two-phase random medium tends to destroy the\nhyperuniformity of the progenitor scalar field. We then propose guidelines to\nachieve effectively hyperuniform two-phase media derived from thresholded\nnon-Gaussian fields. Our investigation paves the way for new research\ndirections to characterize the large-structure spatial patterns that arise in\nphysics, chemistry, biology and ecology. Moreover, our theoretical results are\nexpected to guide experimentalists to synthesize new classes of hyperuniform\nmaterials with novel physical properties via coarsening processes and using\nstate-of-the-art techniques, such as stereolithography and 3D printing.",
        "positive": "Scaling Law for Cracking in Shrinkable Granular Packings: Hydrated granular packings often crack into discrete clusters of grains when\ndried. Despite its ubiquity, accurate prediction of cracking remains elusive.\nHere, we elucidate the previously overlooked role of individual grain\nshrinkage---a feature common to many materials---in determining crack\npatterning using both experiments and simulations. By extending the classical\nGriffith crack theory, we obtain a scaling law that quantifies how cluster size\ndepends on the interplay between grain shrinkage, stiffness, and\nsize---applicable to a diverse array of shrinkable, granular packings."
    },
    {
        "anchor": "Emergent Kelvin waves in chiral active matter: The phenomenological equations of hydrodynamics describe emergent behavior in\nmany body systems. Their forms and the associated phenomena are well\nestablished when the quiescent state of the system is one of thermodynamic\nequilibrium, yet away from equilibrium relatively little is firmly established.\nHere, we deduce directly from first principles the hydrodynamic equations for a\nsystem far from equilibrium, a chiral active fluid in which both parity and\ntime-reversal symmetries are broken. With our theory, we rationalize the\nemergence of a spontaneous boundary current in the confined fluid, a feature\nforbidden at equilibrium, which allows us to extract estimates of transport\ncoefficients that we favorably compare to forced flows. The hydrodynamic\nsolution reveals that the boundary current is analogous to a quasigeostrophic\ncoastal current, a well known phenomenon in oceanography. Such currents are\nconjugate to a class of chiral waves called Kelvin waves. Motivated by this\nanalogy, we demonstrate that an acoustic chiral Kelvin wave mode also exists in\nconfined chiral active matter in the absence of an imposed rotation,\noriginating from the spontaneous emergence of a Coriolis-like parameter in the\nbound modes of a chiral fluid.",
        "positive": "Frenet algorithm for simulations of fluctuating continuous elastic\n  filaments: We present a new algorithm for generating the equilibrium configurations of\nfluctuating continuous elastic filaments, based on a combination of statistical\nmechanics and differential geometry. We use this to calculate the distribution\nfunction of the end-to-end distance of filaments with nonvanishing spontaneous\ncurvature and show that for small twist and large bending rigidities, there is\nan intermediate temperature range in which the filament becomes nearly\ncompletely stretched. We show that volume interactions can be incorporated into\nour algorithm, demonstrating this through the calculation of the effect of\nexcluded volume on the end-to-end distance of the filament."
    },
    {
        "anchor": "Phase separation of stable colloidal clusters: This Article presents a nonequilibrium thermodynamic theory for the\nmean-field precipitation, aggregation and pattern formation of colloidal\nclusters. A variable gradient energy coefficient and the arrest of particle\ndiffusion upon \"jamming\" of cluster aggregates in the spinodal region predicts\nobservable gel patterns that, at high inter-cluster attraction, form\nsystem-spanning, out-of-equilibrium networks with glass-like, quasi-static\nstructural relaxation. For reactive systems, we incorporate the free energy\nlandscape of stable pre-nucleation clusters into the Allen-Cahn-Reaction\nequation. We show that pattern formation is dominantly controlled by the\nDamk\\\"ohler number and the stability of the clusters, which modifies the\nauto-catalytic rate of precipitation. As clusters individually become more\nstable, bulk phase separation is suppressed.",
        "positive": "Mean-field dynamical density functional theory: We examine the out-of-equilibrium dynamical evolution of density profiles of\nultrasoft particles under time-varying external confining potentials in three\nspatial dimensions. The theoretical formalism employed is the dynamical density\nfunctional theory (DDFT) of Marini Bettolo Marconi and Tarazona [J. Chem. Phys.\n{\\bf 110}, 8032 (1999)], supplied by an equilibrium excess free energy\nfunctional that is essentially exact. We complement our theoretical analysis by\ncarrying out extensive Brownian Dynamics simulations. We find excellent\nagreement between theory and simulations for the whole time evolution of\ndensity profiles, demonstrating thereby the validity of the DDFT when an\naccurate equilibrium free energy functional is employed."
    },
    {
        "anchor": "Quasicrystalline order and a crystal-liquid state in a soft-core fluid: A two-dimensional system of soft particles interacting via a two-length-scale\npotential is studied. Density functional theory and Brownian dynamics\nsimulations reveal a fluid phase and two crystalline phases with different\nlattice spacing. Of these the larger lattice spacing phase can form an exotic\nperiodic state with a fraction of highly mobile particles: a crystal liquid.\nNear the transition between this phase and the smaller lattice spacing phase,\nquasicrystalline structures may be created by a competition between linear\ninstability at one scale and nonlinear selection of the other.",
        "positive": "Nanospheres with Patches Arranged in Polyhedrons from Self-Assembly of\n  Solution-State Diblock Copolymers under Spherical Confinement: Self-assembly of sphere-forming solution-state amphiphilic diblock copolymers\nunder spherical nanopore confinement is investigated using a simulated\nannealing technique. For two types of cases of different pore-surface/copolymer\ninteractions, sequences of self-assembled patchy nanospheres are obtained, and\nphase diagrams are constructed. Self-assembled patchy nanospheres with 1-21\nsolvophobic domains are observed. The outermost solvophobic domains (patches)\nare packed into various polyhedrons when their number is larger than 3, where\nthree Platonic solids of a regular tetrahedron, an octahedron, and an\nicosahedron and seven Johnson solids of J12, J13, J17, J50, J51, J86, and J87\nare identified. In addition, another Johnson solid of J84 is identified in a\nstructure with two categories of B-domains. These polyhedrons have all or most\nof their faces in a triangular shape, and hence, they are closer to spherical\nin shape, which may relieve the chain stretching. Nanospheres with 1, 4, 6, 9,\nand 12 numbers of patches occur in relatively large windows in the phase\ndiagrams of both types of cases. In one of the two types of cases, all\nnanospheres with any number of 1-14 patches occur in the phase diagram, whereas\nin the other type of cases, nanospheres with 2, 3, 5, 11, and 13 numbers of\npatches are absent in the phase diagram. Furthermore, at a given pore size, the\nnumber of patches changes nonmonotonically or is unchanged with an increase in\nthe strength of the pore-surface/copolymer interactions for one type or the\nother type of case, respectively. Quantitative calculations are performed to\nelucidate mechanisms of the window size in the phase diagrams of nanospheres\nwith different numbers of patches and structure details."
    },
    {
        "anchor": "Quasi-static mechanics of granular materials: This textbook in French describes the rheology of granular materials in the\nquasi static regime at a macroscopic scale. It starts defining cohesion,\nfriction and the Coulomb approach, from the large-strain range. Then it focuses\non the range of small and intermediate deformation when the medium can dilate\nif it is dense; different specific typical tests (oedometric, constant\npressure, constant volume) are defined, the behaviours they lead are carefully\ndescribed and their dependences upon initial density recalled. Roles of\nfriction and dilatancy are exemplified and their link with the deviatoric\nstress too. \"Natural\" \"phase space\" is defined, which is (specific volume, mean\npressure, axial or deviatoric stress). Then the \"critical\" state, the\n\"characteristic\" state and the Rowe's law of dilatancy are defined, and the\nprevious behaviours analysed in term of plastic deformation, showing that these\nbehaviours obey a specific rule of dissipation. An isotropic incremental\nmodelling is then proposed and studied, with a pseudo Poisson coefficient that\nevolves with the stress ratio. It shows a good agreement with experimental\ntrends, while the theory keeps simple, which describes in particular the\nisochoric compression and the oedometric compression correctly. Cyclic\nbehaviours are then described, and their link with soil liquefaction, with a\npeculiar attention to the role of stress ratio. Basic concepts on micro-macro\npassage are given, starting with a theoretical approach leading to an\nexponential distribution of forces ; then it proposes a theory for the\ncompaction of the medium with pressure, that predicts the v-log(p) law for the\ncritical state.",
        "positive": "Periodic Droplet Formation in Chemically Patterned Microchannels: Simulations show that when a phase-separated binary AB fluid is driven to\nflow past chemically patterned substrates in a microchannel, the fluid exhibits\nunique morphological instabilities. For the pattern studied, these\ninstabilities give rise to the simultaneous, periodic formation of monodisperse\ndroplets of A-in-B and B-in-A. The system bifurcates between time-independent\nbehavior and different types of regular, non-decaying oscillations in the\nstructural characteristics. The surprisingly complex behavior is observed even\nin the absence of hydrodynamic interactions and arises from the interplay\nbetween the fluid flow and patterned substrate, which introduces non-linearity\ninto the dynamical system."
    },
    {
        "anchor": "Effects of Shape on Interaction Dynamics of Tetrahedral Nanoplastics and\n  the Cell Membrane: Cellular uptake of nanoplastics is instrumental in their environmental\naccumulation and transfer to humans through the food chain. Despite extensive\nstudies using spherical plastic nanoparticles, the influence of the\nmorphological characteristics of environmentally released nanoplastics is\nunderstudied. Using dissipative particle dynamics simulations, we modeled the\ninteractions between a cell membrane and hydrophobic nanotetrahedra, which\nfeature high shape anisotropy and large surface curvature seen for\nenvironmental nanoplastics. We observe robust uptake of nanotetrahedra with\nsharp vertices and edges by the lipid membrane. Two local energy minimum\nconfigurations of nanotetrahedra embedded in the membrane bilayer were\nidentified for particles of large sizes. Further analysis of particle dynamics\nwithin the membrane shows that the two interaction states exhibit distinct\ntranslational and rotational dynamics in the directions normal and parallel to\nthe plane of the membrane. The membrane confinement significantly arrests the\nout-of-plane motion, resulting in caged translation and subdiffusive rotation.\nWhile the in-plane diffusion remains Brownian, we find that the translational\nand rotational modes decouple from each other as the particle size increases.\nThe rotational diffusion decreases by a greater extent compared to the\ntranslational diffusion, deviating from the continuum theory predictions. These\nresults provide fundamental insights into the shape effect on the nanoparticle\ndynamics in crowded lipid membranes.",
        "positive": "Kosterlitz-Thouless and Manning Condensation: A comparison between the Kosterlitz-Thouless theory of metal insulator\ntransition in a two dimensional plasma and a counterion condensation in a\npolyelectrolyte solution is made. It is demonstrated that, unlike some of the\nrecent suggestions, the counterion condensation and the Kosterlitz-Thouless\ntransition are distinct."
    },
    {
        "anchor": "Yielding transition of amorphous solids in the presence of aspherical\n  impurities: Understanding the mechanical properties of amorphous solids has been a field\nof intense research not only for the zoo of interesting phenomena one observes\nonce these solids are subjected to external deformations but also for their\nimportance in industrial applications. Amorphous solids are known to have\nhigher yield strength compared to crystalline solids made with similar\ncompositions. However, they fail catastrophically via shear band formation, and\ntuning their mechanical yielding is of significant importance for designing\nbetter materials. For decades, engineers have been working on ways to improve\nthe ability of amorphous solids to sustain external deformations. One popular\nmethod is micro-alloying, which involves adding small amounts of different\nmaterials to the pure sample; while there are many examples of how\nmicro-alloying can improve the yield strain, the microscopic mechanism behind\nit still needs to be better understood. Via extensive molecular dynamics\nsimulation of model amorphous solids, we have studied the effect of elongated\nimpurity particles on the yielding transition of these solids and show that\nrod-like particles can enhance the yield threshold but can also make these\nmaterials more brittle depending on their sphericity and the concentration. In\nparticular, we show that the rotational relaxation of these impurity particles\nplays a significant role in suppressing or enhancing the occurrence of shear\nband formation, which are the main players for the eventual brittle failure of\nany amorphous solids.",
        "positive": "Random self-propulsion to rotational motion of a microswimmer with\n  inertial memory: We study the motion of an inertial microswimmer in a non-Newtonian\nenvironment with a finite memory and present the theoretical realization of an\nunexpected transition from its random self-propulsion to rotational (circular\nor elliptical) motion. Further, the rotational motion of the swimmer is\nfollowed by spontaneous local direction reversals yet with a steady state\nangular diffusion. Moreover, the advent of this behaviour is observed in the\noscillatory regime of the inertia-memory parameter space of the dynamics. We\nquantify this unconventional rotational motion of microswimmer by measuring the\ntime evolution of direction of its instantaneous velocity or orientation. By\nsolving the generalized Langevin model of non-Markovian dynamics of an inertial\nactive Ornstein-Uhlenbeck particle, we show that the emergence of the\nrotational (circular or elliptical) trajectory is due to the presence of\ninertial memory in the environment or medium."
    },
    {
        "anchor": "The Raspberry model for protein-like particles: ellipsoids and\n  confinement in cylindrical pores: The study of protein mass transport via atomistic simulation requires time\nand length scales beyond the computational capabilities of modern computer\nsystems. The raspberry model for colloidal particles in combination with the\nmesoscopic hydrodynamic method of lattice Boltzmann facilitates coarse-grained\nsimulations that are on the order of microseconds and hundreds of nanometers\nfor the study of diffusive transport of protein-like colloid particles. The\nraspberry model reproduces linearity in resistance to motion versus particle\nsize and correct enhanced drag within cylindrical pores at off-center\ncoordinates for spherical particles. Owing to the high aspect ratio of many\nproteins, ellipsoidal raspberry colloid particles were constructed and\nreproduced the geometric resistance factors of Perrin and of Happel and Brenner\nin the laboratory-frame and in the moving body-frame. Accurate body-frame\nrotations during diffusive motion have been captured for the first time using\nprojections of displacements.",
        "positive": "Mechanical regularization: Training materials through periodic drive allows to endow materials and\nstructures with complex elastic functions. As a result of the driving, the\nsystem explores the high dimensional space of structures, ultimately converging\nto a structure with the desired response. However, increasing the complexity of\nthe desired response results in ultra-slow convergence and degradation. Here,\nwe show that by constraining the search space we are able to increase\nrobustness, extend the maximal capacity, train responses that previously did\nnot converge, and in some cases to accelerate convergence by many orders of\nmagnitude. We identify the geometrical constraints that prevent the formation\nof spurious low-frequency modes, which are responsible for failure. We argue\nthat these constraints are analogous to regularization used in machine\nlearning. Our results present a unified understanding of the relations between\ncomplexity, degradation, convergence, and robustness."
    },
    {
        "anchor": "Determination of pressure-viscosity relation of 2,2,4-trimethylhexane by\n  all-atom molecular dynamics simulations: The Newtonian viscosity of 2,2,4-trimethylhexane at 293K is determined at\npressures from 0.1MPa to 1000MPa. Non-equilibrium molecular dynamics\nsimulations are performed using AIREBO-M, an all-atom potential for\nhydrocarbons especially parameterized for high pressures. The steady-state\nshear stress and viscosity are determined from simple shear simulations at\nrates between $10^7$ and $5\\cdot 10^9\\ \\textrm{s}^{-1}$. At low pressures,\nsimulation rates are low enough to reach the Newtonian regime. At high\npressures, results are extrapolated to the Newtonian limit by fitting\nrate-dependent viscosities to Eyring theory. The resulting pressure dependent\nviscosity is typical of small molecules and fits to a common model are\ndiscussed.",
        "positive": "Stripe phase of two-dimensional core-softened systems: structure\n  recognition: In the present paper we discuss a so called stripe phase of two-dimensional\nsystems which was observed in computer simulation of core-softened system and\nin some experiments with colloidal films. We show that the stripe phase is\nindeed an oblique crystal and find out its unit vectors, i.e. we give a full\ndescription of the structure of this crystalline phase."
    },
    {
        "anchor": "Single-Molecule Observation of Long Jumps in Polymer Adsorption: Single-molecule fluorescence imaging of adsorption onto initially-bare\nsurfaces shows that polymer chains need not localize immediately after arrival.\nIn a system optimized to present limited adsorption sites (quartz surface to\nwhich polyethylene glycol (PEG) is exposed in aqueous solution at pH = 8.2) we\nfind that some chains diffuse back into bulk solution and re-adsorb at some\ndistance away, sometimes multiple times before either they localize at a stable\nposition or else diffuse away into bulk solution. This mechanism of surface\ndiffusion is considerably more rapid than the classical model in which adsorbed\npolymers crawl on surfaces while the entire molecule remains adsorbed. The\ntrajectories with jumps follow a truncated Levy distribution of step size with\nlimiting slope -2.5, consistent with a well-defined, rapid surface diffusion\ncoefficient over the times we observe.",
        "positive": "Electric-field induced shape transition of nematic tactoids: The occurrence of new textures of liquid crystals is an important factor in\ntuning their optical and photonics properties. Here, we show, both\nexperimentally and by numerical computation, that under an electric field\nchitin tactoids (i.e. nematic droplets) can stretch to aspect ratios of more\nthan 15, leading to a transition from a spindle-like to a cigar-like shape. We\nargue that the large extensions occur because the elastic contribution to the\nfree energy is dominated by the anchoring. We demonstrate that the elongation\ninvolves hydrodynamic flow and is reversible, the tactoids return to their\noriginal shapes upon removing the field."
    },
    {
        "anchor": "Towards mechanical characterization of soft digital materials for\n  multimaterial 3D-printing: We study mechanical behavior of soft rubber-like digital materials used in\nPolyjet multi-material 3D-printing to create deformable composite materials and\nflexible structures. These soft digital materials are frequently treated as\nlinear elastic materials in the literature. However, our experiments clearly\nshow that these materials exhibit significant non-linearities under large\nstrain regime. Moreover, the materials demonstrate pronounced rate-dependent\nbehavior. In particular, their instantaneous moduli as well as ultimate strain\nand stress significantly depend on the strain rate. To take into account both\nhyper- and viscoelasticity phenomena, we employ the Quasi-Linear Viscoelastic\n(QLV) model with instantaneous Yeoh strain-energy density function. We show\nthat the QLV-Yeoh model accurately describes the mechanical behavior of the\nmajority of the soft digital materials under uniaxial tension.",
        "positive": "Phase Behaviour of Binary Hard-Sphere Mixtures: Free Volume Theory\n  Including Reservoir Hard-Core Interactions: Comprehensive calculations were performed to predict the phase behaviour of\nlarge spherical colloids mixed with small spherical colloids that act as\ndepletant. To this end, the free volume theory (FVT) of Lekkerkerker et al.\n[Europhys. Lett. 20 (1992) 559] is used as a basis and is extended to\nexplicitly include the hard-sphere character of colloidal depletants into the\nexpression for the free volume fraction. Taking the excluded volume of the\ndepletants into account in both the system and the reservoir provides a\nrelation between the depletant concentration in the reservoir and in the system\nthat accurately matches with computer simulation results of Dijkstra et al.\n[Phys. Rev. E 59 (1999) 5744]. Moreover, the phase diagrams for highly\nasymmetric mixtures with size ratios q . 0:2 obtained by using this new\napproach corroborates simulation results significantly better than earlier FVT\napplications to binary hard-sphere mixtures. The phase diagram of a binary\nhard-sphere mixture with a size ratio of q = 0:4, where a binary interstitial\nsolid solution is formed at high densities, is investigated using a numerical\nfree volume approach. At this size ratio, the obtained phase diagram is\nqualitatively different from previous FVT approaches for hard-sphere and\npenetrable depletants, but again compares well with simulation predictions."
    },
    {
        "anchor": "Granular Shear Flow in Varying Gravitational Environments: Despite their very low surface gravities, asteroids exhibit a number of\ndifferent geological processes involving granular matter. Understanding the\nresponse of this granular material subject to external forces in microgravity\nconditions is vital to the design of a successful asteroid sub-surface sampling\nmechanism, and in the interpretation of the fascinating geology on an asteroid.\nWe have designed and flown a Taylor-Couette shear cell to investigate granular\nflow due to rotational shear forces under the conditions of parabolic flight\nmicrogravity. The experiments occur under weak compression. First, we present\nthe technical details of the experimental design with particular emphasis on\nhow the equipment has been specifically designed for the parabolic flight\nenvironment. Then, we investigate how a steady state granular flow induced by\nrotational shear forces differs in varying gravitational environments. We find\nthat the effect of constant shearing on the granular material, in a direction\nperpendicular to the effective acceleration, does not seem to be strongly\ninfluenced by gravity. This means that shear bands can form in the presence of\na weak gravitational field just as on Earth.",
        "positive": "On-Command Disassembly of Microrobotic Superstructures for Transport and\n  Delivery of Magnetic Micromachines: Magnetic microrobots have been developed for navigating microscale\nenvironments by means of remote magnetic fields. However, limited propulsion\nspeeds at small scales remain an issue in the maneuverability of these devices\nas magnetic force and torque are proportional to their magnetic volume. Here,\nwe propose a microrobotic superstructure, which, as analogous to a\nsupramolecular system, consists of two or more microrobotic units that are\ninterconnected and organized through a physical (transient) component (a\npolymeric frame or a thread). Our superstructures consist of microfabricated\nmagnetic helical micromachines interlocked by a magnetic gelatin nanocomposite\ncontaining iron oxide nanoparticles (IONPs). While the microhelices enable the\nmotion of the superstructure, the IONPs serve as heating transducers for\ndissolving the gelatin chassis via magnetic hyperthermia. In a practical\ndemonstration, we showcase the superstructure's motion with a gradient magnetic\nfield in a large channel, the disassembly of the superstructure and release of\nthe helical micromachines by a high-frequency alternating magnetic field, and\nthe corkscrew locomotion of the released helices through a small channel via a\nrotating magnetic field. This adaptable microrobotic superstructure reacts to\ndifferent magnetic inputs, which could be used to perform complex delivery\nprocedures within intricate regions of the human body."
    },
    {
        "anchor": "Simple models for charge and salt effects in protein crystallisation: A simple extension of existing models for protein crystallisation is\ndescribed, in which salt ions and charge neutrality are explicitly\nincorporated. This provides a straightforward explanation for the shape of\nprotein crystallisation boundaries, the associated scaling properties seen for\nlysozyme, and can also explain much of the salt dependence of the second virial\ncoefficient. The analysis has wider implications for the use of pair potentials\nto understand protein crystallisation.",
        "positive": "Active-matter isomorphs in the size-polydisperse Ornstein-Uhlenbeck\n  Lennard-Jones model: This paper studies size-polydisperse Lennard-Jones systems described by\nactive Ornstein-Uhlenbeck particle dynamics. The focus is on the existence of\nisomorphs (curves of invariant structure and dynamics) in the model's\nthree-dimensional phase diagram. Isomorphs are traced out from a single\nsteady-state configuration by means of the configurational-temperature method.\nGood invariance of the reduced-unit radial distribution function and the\nmean-square displacement as a function of time is demonstrated for three\nuniform-distribution polydispersities, 12%, 23%, and 29%. Comparing to\nactive-matter isomorphs generated by the analytical direct-isomorph-check\nmethod, the latter give somewhat poorer invariance of the structure, but better\ninvariance of the dynamics. We conclude that both methods can be used to\nquickly get an overview of the phase diagram of polydisperse AOUP models\ninvolving a potential-energy function obeying the hidden-scale-invariance\nproperty required for isomorph theory to apply."
    },
    {
        "anchor": "Structural Reorganization of Parallel Actin Bundles by Crosslinking\n  Proteins: Incommensurate States of Twist: We construct a coarse-grained model of parallel actin bundles crosslinked by\ncompact, globular bundling proteins, such as fascin and espin, necessary\ncomponents of filapodial and mechanosensory bundles. Consistent with structural\nobservations of bundles, we find that the optimal geometry for crosslinking is\novertwisted, requiring a coherent structural change of the helical geometry of\nthe filaments. We study the linker-dependent thermodynamic transition of\nbundled actin filaments from their native state to the overtwisted state and\nmap out the \"twist-state'' phase diagram in terms of the availability as well\nas the flexibility of crosslinker proteins. We predict that the transition from\nthe uncrosslinked to fully-crosslinked state is highly sensitive to linker\nflexibility: flexible crosslinking smoothly distorts the twist-state of bundled\nfilaments, while rigidly crosslinked bundles undergo a phase transition,\nrapidly overtwisting filaments over a narrow range of free crosslinker\nconcentrations. Additionally, we predict a rich spectrum of intermediate\nstructures, composed of alternating domains of sparsely-bound (untwisted) and\nstrongly-bound (overtwisted) filaments. This model reveals that subtle\ndifferences in crosslinking agents themselves modify not only the detailed\nstructure of parallel actin bundles, but also the thermodynamic pathway by\nwhich they form.",
        "positive": "Measuring contact angle and meniscus shape with a reflected laser beam: Side-view imaging of the contact angle between an extended planar solid\nsurface and a liquid is problematic. Even when aligning the view perfectly\nparallel to the contact line, focusing one point of the contact line is not\npossible. We describe a new measurement technique for determining contact\nangles with the reflection of a widened laser sheet on a moving contact line.\nWe verified this new technique measuring the contact angle on a cylinder,\nrotating partially immersed in a liquid. A laser sheet is inclined under an\nangle $\\varphi$ to the unperturbed liquid surface and is reflected off the\nmeniscus. Collected on a screen, the reflection image contains information to\ndetermine the contact angle. When dividing the laser sheet into an array of\nlaser rays by placing a mesh into the beam path, the shape of the meniscus can\nbe reconstructed from the reflection image. We verified the method by measuring\nthe receding contact angle versus speed for aqueous cetyltrimethyl ammonium\nbromide solutions on a smooth hydrophobized as well as on a rough polystyrene\nsurface."
    },
    {
        "anchor": "Implicit Chain Particle Model for Polymer Grafted Nanoparticles: Matrix-free nanocomposites made from polymer grafted nanoparticles (PGN)\nrepresent a paradigm shift in materials science because they greatly improve\nnanoparticle dispersion and offer greater tunability over rheological and\nmechanical properties in comparison to neat polymers. Utilizing the full\npotential of PGNs requires a deeper understanding of how polymer graft length,\ndensity, and chemistry influence interfacial interactions between particles.\nThere has been great progress in describing these effects with molecular\ndynamics (MD). However, the limitations of the length and time scales of MD\nmake it prohibitively costly to study systems involving more than a few PGNs.\nHere, we address some of these challenges by proposing a new modeling paradigm\nfor PGNs using a strain-energy mapping framework involving potential of mean\nforce (PMF) calculations. In this approach, each nanoparticle is coarse-grained\ninto a representative particle with chains treated implicitly, namely, the\nimplicit chain particle model (ICPM). Using a chemistry-specific CG-MD model of\nPMMA as a testbed, we derive the effective interaction between particles\narranged in a closed-packed lattice configuration by matching bulk\ndilation/compression strain energy densities. The strain-rate dependence of the\nmechanical work in ICPM is also discussed. Overall, the ICPM model increases\nthe computational speed by approximately 5-6 orders of magnitude compared to\nthe CG-MD models. This novel framework is foundational for particle-based\nsimulations of PGNs and their blends and accelerates the understanding and\npredictions of emergent properties of PGN materials.",
        "positive": "Calculation of the Voronoi boundary for lens-shaped particles and\n  spherocylinders: We have recently developed a mean-field theory to estimate the packing\nfraction of non-spherical particles [A. Baule et al., Nature Commun. (2013)].\nThe central quantity in this framework is the Voronoi excluded volume, which\ngeneralizes the standard hard-core excluded volume appearing in Onsager's\ntheory. The Voronoi excluded volume is defined from an exclusion condition for\nthe Voronoi boundary between two particles, which is usually not tractable\nanalytically. Here, we show how the technical difficulties in calculating the\nVoronoi boundary can be overcome for lens-shaped particles and spherocylinders,\ntwo standard prolate and oblate shapes with rotational symmetry. By decomposing\nthese shapes into unions and intersections of spheres analytical expressions\ncan be obtained."
    },
    {
        "anchor": "Work extraction and performance of colloidal heat engines in\n  viscoelastic baths: A colloidal particle embedded in a fluid can be used as a microscopic heat\nengine by means of a sequence of cyclic transformations imposed by an optical\ntrap. We investigate a model for the operation of such kind of Brownian engines\nwhen the surrounding medium is viscoelastic, which endows the particle dynamics\nwith memory friction. We analyze the effect of the relaxation time of the fluid\non the performance of the colloidal engine under finite-time Stirling cycles.\nWe find that, due to the frequency-dependence of the friction in viscoelastic\nfluids, the mean power delivered by the engine and its efficiency can be highly\nenhanced as compared to those in a viscous environment with the same zero-shear\nviscosity. In addition, with increasing fluid relaxation time the interval of\ncycle times at which positive power output can be delivered by the engine\nbroadens. Our results reveal the importance of the transient behavior of the\nfriction experienced by a Brownian heat engine in a complex fluid, which cannot\nbe neglected when driven by thermodynamic cycles of finite duration.",
        "positive": "Coexistence of active and hydrodynamic turbulence in two dimensional\n  active nematics: In active nematic liquid crystals activity is able to drive chaotic\nspatiotemporal flows referred to as active turbulence. Active turbulence has\nbeen characterized through theoretical and experimental work as a low Reynolds\nnumber phenomenon. We show that, in two-dimensions, the active forcing alone is\nable to trigger hydrodynamic turbulence leading to the coexistence of active\nand inertial turbulence. This type of flows develops for sufficiently active\nand extensile flow-aligning nematics. We observe that the combined effect of an\nextensile nematic and large values of the flow-aligning parameter leads to a\nbroadening of the elastic energy spectrum that promotes a growth of kinetic\nenergy able to trigger an inverse energy cascade."
    },
    {
        "anchor": "Virial expansions and augmented van der Waals approach: Application to\n  Lennard-Jones-like Yukawa fluid: We argue that recently proposed [Melnyk et al., Fluid Phase Equilibr., 2009,\nVol. 279, 1] a criterion to split the pair interaction energy into two parts,\none of which is forced to be responsible the most accurate as possible for\nexcluded volume energy in the system, results in expressions for the virial\ncoefficients that improve the performance of the virial equation of state in\ngeneral, and at subcritical temperatures, in particular. As an example,\napplication to the Lennard-Jones-like hard-core attractive Yukawa fluid is\ndiscussed.",
        "positive": "DNA Self-Assembly and Computation Studied with a Coarse-grained Dynamic\n  Bonded Model: We study DNA self-assembly and DNA computation using a coarse-grained DNA\nmodel within the directional dynamic bonding framework {[}C. Svaneborg, Comp.\nPhys. Comm. 183, 1793 (2012){]}. In our model, a single nucleotide or domain is\nrepresented by a single interaction site. Complementary sites can reversibly\nhybridize and dehybridize during a simulation. This bond dynamics induces a\ndynamics of the angular and dihedral bonds, that model the collective effects\nof chemical structure on the hybridization dynamics. We use the DNA model to\nperform simulations of the self-assembly kinetics of DNA tetrahedra, an\nicosahedron, as well as strand displacement operations used in DNA computation."
    },
    {
        "anchor": "Leidenfrost Gas Ratchets Driven by Thermal Creep: We show that thermal creep is at the origin of the recently discovered\nLeidenfrost ratchet, where liquid droplets float on a vapor layer along a\nheated sawtooth surface and accelerate to velocities of up to 40 cm=s. As the\nactive element, the asymmetric temperature profile at each ratchet summit\nrectifies the vapor flow in the boundary layer. This mechanism works at low\nReynolds number and provides a novel tool for controlling gas flow at\nnanostructured surfaces.",
        "positive": "A minimal coarse-grained model to study the gelation of multi-armed DNA\n  nanostars: DNA is an astonishing material that can be used as a molecular building block\nto construct periodic arrays and devices with nanoscale accuracy and precision.\nHere, we present simple bead-spring model of DNA nanostars having three, four\nand five arms and study their self-assembly using molecular dynamics\nsimulations. Our simulations show that the DNA nanostars form thermodynamically\nstable fully bonded gel phase from an unstructured liquid phase with the\nlowering of temperature. We characterize the phase transition by calculating\nseveral structural features such as radial distribution function and structure\nfactor. The thermodynamics of gelation is quantified by the potential energy\nand translational pair-entropy of the system. The phase transition from the\narrested gel phase to an unstructured liquid phase has been modelled using\ntwo-state theoretical model. We find that this transition is enthalpic driven\nand loss of configuration and translational entropy is counterpoised by\nenthalpic interaction of the DNA sticky-ends which is giving rise to gel phase\nat low temperature. The absolute rotational and translational entropy of the\nsystems, measured using two-phase thermodynamic model, also substantiate the\ngel transition. The slowing down of the dynamics upon approaching the\ntransition temperature from a high temperature, demonstrating the phase\ntransition to the gel phase. The detailed numerical simulation study of the\nmorphology, dynamics and thermodynamics of DNA gelation can provide guidance\nfor future experiments, easily extensible to other polymeric systems, and has\nremarkable implications in the DNA nanotechnology field."
    },
    {
        "anchor": "Potential \"ways of thinking\" about the shear-banding phenomenon: Shear-banding is a curious but ubiquitous phenomenon occurring in soft\nmatter. The phenomenological similarities between the shear-banding transition\nand phase transitions has pushed some researchers to adopt a 'thermodynamical'\napproach, in opposition to the more classical 'mechanical' approach to fluid\nflows. In this heuristic review, we describe why the apparent dichotomy between\nthose approaches has slowly faded away over the years. To support our\ndiscussion, we give an overview of different interpretations of a single\nequation, the diffusive Johnson-Segalman (dJS) equation, in the context of\nshear-banding. We restrict ourselves to dJS, but we show that the equation can\nbe written in various equivalent forms usually associated with opposite\napproaches. We first review briefly the origin of the dJS model and its initial\nrheological interpretation in the context of shear-banding. Then we describe\nthe analogy between dJS and reaction-diffusion equations. In the case of\nanisotropic diffusion, we show how the dJS governing equations for steady shear\nflow are analogous to the equations of the dynamics of a particle in a quartic\npotential. Going beyond the existing literature, we then draw on the Lagrangian\nformalism to describe how the boundary conditions can have a key impact on the\nbanding state. Finally, we reinterpret the dJS equation again and we show that\na rigorous effective free energy can be constructed, in the spirit of early\nthermodynamic interpretations or in terms of more recent approaches exploiting\nthe language of irreversible thermodynamics.",
        "positive": "Directional Wetting of Submerged Gas-entrapping Microtextures: Numerous natural and industrial processes entail the spontaneous entrapment\nof gas/air as rough/patterned surfaces are submerged under water. As the\nwetting transitions ensue, the gas diffuses into the water leading to the\nfully-water-filled state. However, the standard models for wetting do not\naccount for the microtexture's topography. In other words, it is not clear\nwhether the lifetime of n cavities arranged in a I-D line or a II-D (circular\nor square) lattice would be the same or not as a single 0-D cavity. In\nresponse, we tracked the time-dependent fates of gas pockets trapped in I-D and\nII-D lattices and compared them with wetting transitions in commensurate 0-D\ncavities. Interestingly, the wetting transitions in the I-D and the II-D arrays\nhad a directionality such that the gas from the outermost cavities was lost the\nfirst, while the innermost got filled by water the last. In essence,\nmicrotexture's spatial organization afforded shielding to the loss of the gas\nfrom the innermost cavities, which we probed as a function of the\nmicrotexture's pitch, surface density, dimensionality, and hydrostatic\npressure. These findings advance our knowledge of wetting transitions in\nmicrotextures, and inspiring surface textures to protect electronic devices\nagainst liquid ingression."
    },
    {
        "anchor": "Effective Perrin theory for the anisotropic diffusion of a strongly\n  hindered rod: Slender rods in concentrated suspensions constitute strongly interacting\nsystems with rich dynamics: transport slows down drastically and the anisotropy\nof the motion becomes arbitrarily large. We develop a mesoscopic description of\nthe dynamics down to the length scale of the interparticle distance. Our theory\nis based on the exact solution of the Smoluchowski-Perrin equation; it is in\nquantitative agreement with extensive Brownian dynamics simulations in the\ndense regime. In particular, we show that the tube confinement is characterised\nby a power law decay of the intermediate scattering function with exponent 1/2.",
        "positive": "Probing an nonequilibrium Einstein relation in an aging colloidal glass: We present a direct experimental measurement of an effective temperature in a\ncolloidal glass of Laponite, using a micrometric bead as a thermometer. The\nnonequilibrium fluctuation-dissipation relation, in the particular form of a\nmodified Einstein relation, is investigated with diffusion and mobility\nmeasurements of the bead embedded in the glass. We observe an unusual\nnon-monotonic behavior of the effective temperature : starting from the bath\ntemperature, it is found to increase up to a maximum value, and then decreases\nback, as the system ages. We show that the observed deviation from the Einstein\nrelation is related to the relaxation times previously measured in dynamic\nlight scattering experiments."
    },
    {
        "anchor": "Force distributions in a triangular lattice of rigid bars: We study the uniformly weighted ensemble of force balanced configurations on\na triangular network of nontensile contact forces. For periodic boundary\nconditions corresponding to isotropic compressive stress, we find that the\nprobability distribution for single-contact forces decays faster than\nexponentially. This super-exponential decay persists in lattices diluted to the\nrigidity percolation threshold. On the other hand, for anisotropic imposed\nstresses, a broader tail emerges in the force distribution, becoming a pure\nexponential in the limit of infinite lattice size and infinitely strong\nanisotropy.",
        "positive": "Sacrificial bonds and hidden length in biomaterials -- a kinetic,\n  constitutive description of strength and toughness in bone: Sacrificial bonds and hidden length in structural molecules account for the\ngreatly increased fracture toughness of biological materials compared to\nsynthetic materials without such structural features, by providing a\nmolecular-scale mechanism for energy dissipation. One example is in the\npolymeric glue connection between collagen fibrils in animal bone. In this\npaper, we propose a simple kinetic model that describes the breakage of\nsacrificial bonds and the release of hidden length, based on Bell's theory. We\npostulate a master equation governing the rates of bond breakage and formation.\nThis enables us to predict the mechanical behavior of a quasi-one-dimensional\nensemble of polymers at different stretching rates. We find that both the\nrupture peak heights and maximum stretching distance increase with the\nstretching rate. In addition, our theory naturally permits the possibility of\nself-healing in such biological structures."
    },
    {
        "anchor": "Artificial neural networks for predicting the viscosity of\n  lead-containing glasses: The viscosity of lead-containing glasses is of fundamental importance for the\nmanufacturing process, and can be predicted by algorithms such as artificial\nneural networks. The SciGlass database was used to provide training, validation\nand test data of chemical composition, temperature and viscosity for the\nconstruction of artificial neural networks with node variation in the hidden\nlayer. The best model built with training data and validation data was compared\nwith 7 other models from the literature, demonstrating better statistical\nevaluations of mean absolute error and coefficient of determination to the test\ndata, with subsequent sensitivity analysis in agreement with the literature.\nSkewness and kurtosis were calculated and there is a good correlation between\nthe values predicted by the best neural network built with the test data.",
        "positive": "Force-Dependent Folding Kinetics of Single Molecules with Multiple\n  Intermediates and Pathways: Most single-molecule studies derive the kinetic rates of native,\nintermediate, and unfolded states from equilibrium hopping experiments. Here,\nwe apply Kramers kinetic diffusive model to derive the force-dependent kinetic\nrates of intermediate states from non-equilibrium pulling experiments. From the\nkinetic rates, we also extract the force-dependent kinetic barriers and the\nequilibrium folding energies. We apply our method to DNA hairpins with multiple\nfolding pathways and intermediates. The experimental results agree with\ntheoretical predictions. Furthermore, the proposed non-equilibrium\nsingle-molecule approach permits us to characterize kinetic and thermodynamic\nproperties of native, unfolded, and intermediate states that cannot be derived\nfrom equilibrium hopping experiments."
    },
    {
        "anchor": "Gas-Mediated Impact Dynamics in Fine-Grained Granular Materials: Non-cohesive granular media exhibit complex responses to sudden impact that\noften differ from those of ordinary solids and liquids. We investigate how this\nresponse is mediated by the presence of interstitial gas between the grains.\nUsing high-speed x-ray radiography we track the motion of a steel sphere\nthrough the interior of a bed of fine, loose granular material. We find a\ncrossover from nearly incompressible, fluid-like behavior at atmospheric\npressure to a highly compressible, dissipative response once most of the gas is\nevacuated. We discuss these results in light of recent proposals for the drag\nforce in granular media.",
        "positive": "Active Rheology and Anti-Commensuration Effects For Driven Probe\n  Particles on Two Dimensional Periodic Pinning Substrates: For an assembly of particles interacting with a two dimensional periodic\nsubstrate, a series of commensuration effects can arise when the number of\nparticles is an integer multiple of the number of substrate minima. Such\ncommensuration effects can appear for vortices in type-II superconductors with\nperiodic pinning or for colloidal particles on optical landscapes. Under bulk\nexternal driving, the pinning or drag on the particles is strongly enhanced at\ncommensuration. Here we consider the active rheology of a single particle\ndriven through an assembly of particles coupled to a periodic substrate at\ndifferent commensurate conditions. For increasing density at fixed driving\nforce, we observe nonmonotonic drag along with what we call an\nanti-commensuration effect where the drag or pinning effectiveness is reduced\nin commensurate states, opposite from the behavior typically observed under\nbulk driving. The velocity enhancement or drag reduction appears when the\nbackground particles form a crystalline state that is coupled more strongly to\nthe substrate than to the driven particle, while under incommensurate\nconditions, the background particles are disordered and produce enhanced drag\non the probe particle. The velocity noise of the driven particle has a narrow\nband signature at commensuration and a broad band signature away from\ncommensuration. We map out the regions in which viscous flow, periodic flow,\nand a pinned phase appear. We show that the effects we observe are robust on\nboth square and triangular substrate arrays and for both vortices in type-II\nsuperconductors and colloidal particles on optical landscapes."
    },
    {
        "anchor": "Collapse modes in SC and BCC arrangements of elastic beads: Collapse modes in compressed simple cubic (SC) and body-centered cubic (BCC)\nperiodic arrangements of elastic frictionless beads were studied numerically\nusing the discrete element method. Under pure hydrostatic compression, the SC\narrangement tends to transform into a defective hexagonal close-packed or\namorphous structure. The BCC assembly exhibits several modes of collapse, one\nof which, identified as cI16 structure, is consistent with the behavior of BCC\nmetals Li and Na under high pressure. The presence of a deviatoric stress leads\nto the transformation of the BCC structure into face-centered cubic (FCC) one\nvia the Bain path. The observed effects provide important insights on the\norigins of mechanical behavior of atomic systems, while the elastic spheres\nmodel used in our work can become a useful paradigm, expanding the capabilities\nof a hard sphere model widely used in many branches of science.",
        "positive": "Nonlinear smectic elasticity of a helical state in cholesterics and\n  helimagnets: General symmetry arguments, dating back to de Gennes dictate that at scales\nlonger than the pitch, the low-energy elasticity of a chiral nematic liquid\ncrystal (cholesteric) and of a Dzyaloshinskii-Morya (DM) spiral state in a\nhelimagnet with negligible crystal symmetry fields (e.g., MnSi, FeGe) is\nidentical to that of a smectic liquid crystal, thereby inheriting its rich\nphenomenology. Starting with a chiral Frank free-energy (exchange and DM\ninteractions of a helimagnet) we present a transparent derivation of the fully\nnonlinear Goldstone mode elasticity, which involves an analog of the\nAnderson-Higgs mechanism that locks the spiral orthonormal (director/magnetic\nmoment) frame to the cholesteric (helical) layers. This shows explicitly the\nreduction of three orientational modes of a cholesteric down to a single phonon\nGoldstone mode that emerges on scales longer than the pitch. At a harmonic\nlevel our result reduces to that derived many years ago by Lubensky and\ncollaborators."
    },
    {
        "anchor": "Bacteria Through Obstacles: Unifying Fluxes, Entropy Production, and\n  Extractable Work in Living Active Matter: Thermodynamic equilibrium is a unique state characterized by time-reversal\nsymmetry, which enforces zero fluxes and prohibits work extraction from a\nsingle thermal bath. By virtue of being microscopically out of equilibrium,\nactive matter challenges these defining characteristics of thermodynamic\nequilibrium. Although time irreversibility, fluxes, and extractable work have\nbeen observed separately in various non-equilibrium systems, a comprehensive\nunderstanding of these quantities and their interrelationship in the context of\nliving matter remains elusive. Here, by combining experiments, simulations, and\ntheory, we study the correlation between these three quantities in a single\nsystem consisting of swimming Escherichia coli navigating through funnel-shaped\nobstacles. We show that the interplay between geometric constraints and\nbacterial swimming breaks time-reversal symmetry, leading to the emergence of\nlocal mass fluxes. Using an harmonically trapped colloid coupled weakly to\nbacterial motion, we demonstrate that the amount of extractable work depends on\nthe deviation from equilibrium as quantified by fluxes and entropy production.\nWe propose a minimal mechanical model and a generalized mass transfer relation\nfor bacterial rectification that quantitatively explains experimental\nobservations. Our study provides a microscopic understanding of bacterial\nrectification and uncovers the intrinsic relation between time irreversibility,\nfluxes, and extractable work in living systems far from equilibrium.",
        "positive": "Dynamic phase separation of fluid membranes with rigid inclusions: Membrane shape fluctuations induce attractive interactions between rigid\ninclusions. Previous analytical studies showed that the fluctuation-induced\npair interactions are rather small compared to thermal energies, but also that\nmulti-body interactions cannot be neglected. In this article, it is shown\nnumerically that shape fluctuations indeed lead to the dynamic separation of\nthe membrane into phases with different inclusion concentrations. The tendency\nof lateral phase separation strongly increases with the inclusion size. Large\ninclusions aggregate at very small inclusion concentrations and for relatively\nsmall values of the inclusions' elastic modulus."
    },
    {
        "anchor": "Dynamics of a polymer under multi-gradient fields: Effects of multi-gradient fields on the transport of a polymer chain have\nbeen investigated by using generalized Langevin dynamics simulations. We\nobserve that the natural frequency of tumbling follows $Wi^{0.66}$ scaling,\nwhere $Wi$ is the Weissenberg number. Analysis of angular tumbling time\ndistribution reveals that the tail of distribution follows exponential\ndistribution and at high Weissenberg number, deviates from Poisson behaviour.\nCompetition between velocity gradient which results shear flow in the system,\nand solvent quality gradient arising due to the interaction among monomers\nrevealed that there is another scaling associated with the angular tumbling\ntime distribution. Moreover, at low temperature, we observe unusual behaviour\nthat at intermediate shear rates, decay rate $\\nu$ decreases with $Wi$.",
        "positive": "Use of Digital Image Correlation to study the effect of temperature on\n  the development of plastic instabilities in a semi-crystalline polymer: The plastic deformation processes that occur in a tensily deformed High\nDensity Polyethylene specimen were studied from full-field strain and strain\nrate measurements obtained by 3D DIC (Digital Image Correlation).The tensile\ntests were performed every 10{\\textdegree}C from room temperature to\n120{\\textdegree}C . For temperatures below 60{\\textdegree}C , it is shown that\nthe strain localization effect becomes less pronounced when the temperature\nincreases. For temperatures higher than 60{\\textdegree}C , the material is\nfound to exhibit double yielding behavior. By analyzing the DIC data in\nLagrangian representation, it was possible to quantitatively highlight the\nstrain localization effect that is specifically associated with the second\nyield. The second yield strain (E_{Y_2}) was measured and appeared to be\nindependent of temperature. For temperatures smaller than 60{\\textdegree}C , it\nwas found that the threshold strain corresponding to (E_{Y_2}) also marks the\nonset of the deformation process phase during which the volume strain strongly\nincreases. Based on previous studies of our research team and on literature we\nconcluded that the critical strain (E_{Y_2}) corresponds to the onset of the\nlamellar morphology destruction. At high strain levels, the neck stabilization\nphase was shown to proceed according to a strain driven scheme characterized by\nthreshold strains that are temperature independent. The experimental values of\nthe threshold strain marking the onset of the stabilization phase are found to\nbe in good agreement with those found using the Haward-Thackray model."
    },
    {
        "anchor": "Ion Hydration and Associated Defects in Hydrogen Bond Network of Water:\n  Observation of Reorientationally Slow Water Molecules Beyond First Hydration\n  Shell in Aqueous Solutions of MgCl$_2$: Effects of presence of ions, at moderate to high concentrations, on dynamical\nproperties of water molecules are investigated through classical molecular\ndynamics simulations using two well known non-polarizable water models.\nSimulations reveal that the presence of magnesium chloride (MgCl$_2$) induces\nperturbations in the hydrogen bond network of water leading to the formation of\nbulk-like domains with \\textquoteleft defect sites\\textquoteright~on boundaries\nof such domains: water molecules at such defect sites have less number of\nhydrogen bonds than those in bulk water. Reorientational autocorrelation\nfunctions for dipole vectors of such defect water molecules are computed at\ndifferent concentrations of ions and compared with system of pure water.\nEarlier experimental and simulation studies indicate significant differences in\nreorientational dynamics for water molecules in the first hydration shell of\nmany dissolved ions. Results of this study suggest that defect water molecules,\nwhich are beyond the first hydration shells of ions, also experience\nsignificant slowing down of reorientation times as a function of concentration\nin the case of MgCl$_2$. However, addition of cesium chloride(CsCl) to water\ndoes not perturb the hydrogen bond network of water significantly even at\nhigher concentrations. This difference in behavior between MgCl$_2$ and CsCl is\nconsistent with the well-known Hofmeister series.",
        "positive": "Smoothing of sandpile surfaces after intermittent and continuous\n  avalanches: three models in search of an experiment: We present and analyse in this paper three models of coupled continuum\nequations all united by a common theme: the intuitive notion that sandpile\nsurfaces are left smoother by the propagation of avalanches across them. Two of\nthese concern smoothing at the `bare' interface, appropriate to intermittent\navalanche flow, while one of them models smoothing at the effective surface\ndefined by a cloud of flowing grains across the `bare' interface, which is\nappropriate to the regime where avalanches flow continuously across the\nsandpile."
    },
    {
        "anchor": "Intermolecular forces at ice and water interfaces: premelting, surface\n  freezing and regelation: Using Lifshitz theory we assess the role of van der Waals forces at\ninterfaces of ice and water. The results are combined with measured structural\nforces from computer simulations to develop a quantitative model of the surface\nfree energy of premelting films. This input is employed within the framework of\nwetting theory and allows us to predict qualitatively the behavior of\nquasi-liquid layer thickness as a function of ambient conditions. Our results\nemphasizes the significance of vapor pressure. The ice vapor interface is shown\nto exhibit only incomplete premelting, but the situation can shift to a state\nof complete surface melting above water saturation. The results obtained serve\nalso to assess the role of subsurface freezing at the water-vapor interface,\nand we show that intermolecular forces favor subsurface ice nucleation only in\nconditions of water undersaturation. We show ice regelation at ambient pressure\nmay be explained as a process of capillary freezing, without the need to invoke\nthe action of bulk pressure melting. Our results for van der Waals forces are\nexploited in order to gauge dispersion interactions in empirical point charge\nmodels of water.",
        "positive": "How granular materials deform in quasistatic conditions: Based on numerical simulations of quasistatic deformation of model granular\nmaterials, two rheological regimes are distinguished, according to whether\nmacroscopic strains merely reflect microscopic material strains within the\ngrains in their contact regions (type I strains), or result from instabilities\nand contact network rearrangements at the microscopic level (type II strains).\nWe discuss the occurrence of regimes I and II in simulations of model materials\nmade of disks (2D) or spheres (3D). The transition from regime I to regime II\nin monotonic tests such as triaxial compression is different from both the\nelastic limit and from the yield threshold. The distinction between both types\nof response is shown to be crucial for the sensitivity to contact-level\nmechanics, the relevant variables and scales to be considered in\nmicromechanical approaches, the energy balance and the possible occurrence of\nmacroscopic instabilities"
    },
    {
        "anchor": "Diffusion of an ellipsoid in bacterial suspensions: Active matter such as swarming bacteria and motile colloids exhibits exotic\nproperties different from conventional equilibrium materials. Among these\nproperties, the enhanced diffusion of tracer particles is generally deemed as a\nhallmark of active matter. Here, rather than spherical tracers, we investigate\nthe diffusion of isolated ellipsoids in quasi-two-dimensional bacterial bath.\nOur study reveals a nonlinear enhancement of both translational and rotational\ndiffusions. More importantly, we uncover an anomalous coupling between\ntranslation and rotation that is strictly prohibited in the classic Brownian\ndiffusion. Combining experiments with theoretical modeling, we show that such\nan anomaly arises from generic stretching flows induced by swimming bacteria.\nOur work illustrates a universal organizing principle of active matter and\nsheds new light on fundamental transport processes in microbiological systems.",
        "positive": "The Affinity of the Sulfate- and Ether-Containing Surface-Active Ionic\n  Liquids to Carbon Dioxide, Hydrogen Fluoride, Hydrogen Sulfide, and Water: The development of novel task-specific ionic liquids (ILs) represents an\nessential challenge in modern organic and physical chemistries. Recently we\nreported surface-active ILs contained the two well-known organic cations\n(1-butyl-3-methylimidazolium and tetrabutylammonium) and the two surface-active\nanions (lauryl sulfate, lauryl ether sulfate). In the present work, we\ninvestigate the affinity of these ionic compounds to the selected small\nmolecules that exhibit practical implications: water, hydrogen fluoride,\nhydrogen sulfate, and carbon dioxide. We identified that the sulfate group, the\nether groups, and the aromatic imidazole ring make the strongest contributions\nto the physical sorption of the polar gas molecules. In turn, the\ntetrabutylammonium cation, the saturated hydrocarbon chain of the anions, and\nthe alkyl chains of 1-butyl-3-methylimidazolium contribute to a significantly\nsmaller extent. The reported data are interesting in the context of using\nsurface-active ILs in the oil industry to capture and store undesirable and\ntoxic gases."
    },
    {
        "anchor": "Computer Simulations and Mode-Coupling Theory of Glass-Forming Confined\n  Hard-Sphere Fluids: We present mode-coupling theory (MCT) results for densely packed hard-sphere\nfluids confined between two parallel walls and compare them quantitatively to\ncomputer simulations. The numerical solution of MCT is calculated for the first\ntime using the full system of matrix-valued integro-differential equations. We\ninvestigate several dynamical properties of supercooled liquids including\nscattering functions, frequency-dependent susceptibilities and mean-square\ndisplacements. Close to the glass transition, we find quantitative agreement\nbetween the coherent scattering function predicted from theory and evaluated\nfrom simulations, which enables us to make quantitative statements on caging\nand relaxation dynamics of the confined hard-sphere fluid.",
        "positive": "Contact Kinetics in Fractal Macromolecules: We consider the kinetics of first contact between two monomers of the same\nmacromolecule. Relying on a fractal description of the macromolecule, we\ndevelop an analytical method to compute the Mean First Contact Time (MFCT) for\nvarious molecular sizes. In our theoretical description, the non-Markovian\nfeature of monomer motion, arising from the interactions with the other\nmonomers, is captured by accounting for the non-equilibrium conformations of\nthe macromolecule at the very instant of first contact. This analysis reveals a\nsimple scaling relation for the MFCT between two monomers, which involves only\ntheir equilibrium distance and the spectral dimension of the macromolecule,\nindependently of its microscopic details. Our theoretical predictions are in\nexcellent agreement with numerical stochastic simulations."
    },
    {
        "anchor": "Hydrodynamics of Multicomponent Vesicles Under Strong Confinement: We numerically investigate the hydrodynamics and membrane dynamics of\nmulticomponent vesicles in two strongly confined geometries. This serves as a\nsimplified model for red blood cells undergoing large deformations while\ntraversing narrow constrictions. We propose a new parameterization for the\nbending modulus that remains positive for all lipid phase parameter values. For\na multicomponent vesicle passing through a stenosis, we establish connections\nbetween various properties: lipid phase coarsening, size and flow profile of\nthe lubrication layers, excess pressure, and the tank-treading velocity of the\nmembrane. For a multicomponent vesicle passing through a contracting channel,\nwe find that the lipid always phase separates so that the vesicle is stiffer in\nthe front as it passes through the constriction. For both cases of confinement,\nwe find that lipid coarsening is arrested under strong confinement and proceeds\nat a high rate upon relief from extreme confinement. The results may be useful\nfor efficient sorting lipid domains using microfluidic flows by controlled\nrelease of vesicles passing through strong confinement",
        "positive": "Fluorination Increases Hydrophobicity at the Macroscopic Level but not\n  at the Microscopic Level: Hydrophobic interactions have been studied in detail in the past based on\nhydrophobic polymers, such as polystyrene (PS). Because fluorinated materials\nhave relatively low surface energy, they often show both oleophobicity and\nhydrophobicity at the macroscopic level. However, it remains unknown how\nfluorination of hydrophobic polymer influences hydrophobicity at the\nmicroscopic level. In this work, we synthesized PS and fluorine-substituted PS\n(FPS) by reversible addition-fragmentation chain transfer polymerization\nmethod. Contact angle measurements confirmed that FPS is more hydrophobic than\nPS at the macroscopic level due to the introduction of fluorine. However,\nsingle molecule force spectroscopy experiments showed that the forces required\nto unfold the PS and FPS nanoparticles in water are indistinguishable,\nindicating that the strength of the hydrophobic ffect that drives the\nself-assembly of PS and FPS nanoparticles is the same at the microscopic level.\nThe divergence of hydrophobic effect at the macroscopic and microscopic level\nmay hint different underlying mechanisms: the hydrophobicity is dominated by\nthe solvent hydration at the microscopic level and the surface-associated\ninteraction at the macroscopic level."
    },
    {
        "anchor": "Hydrodynamic assembly of active colloids: chiral spinners and dynamic\n  crystals: Active colloids self-organise to a variety of collective states, ranging from\nhighly motile 'molecules' to complex 3D structures. Using large-scale\nsimulations, we show that hydrodynamic interactions, together with a\ngravity-like aligning field, lead to tunable self-assembly of active colloidal\nspheres near a surface. The observed structures depend on the hydrodynamic\ncharacteristics: particles driven at the front, pullers, form small chiral\nspinners consisting of two or three particles, whereas those driven at the\nrear, pushers, assemble to large dynamic aggregates. The rotational motion of\nthe puller spinners, arises from spontaneous breaking of the internal\nchirality. Our results show that the fluid flow mediates chiral transfer\nbetween neighboring spinners. Finally we show that the chirality of the\nindividual spinners controls the topology of the self-assembly in solution:\nhomochiral samples assemble into a hexagonally symmetric 2D crystal lattice\nwhile racemic mixtures show reduced hexatic order with diffusion-like dynamics.",
        "positive": "Seeding Approach to nucleation in the NVT ensemble: the case of bubble\n  cavitation in overstretched Lennard Jones fluids: Simulations are widely used to study nucleation in first order phase\ntransitions due to the fact that they have access to the relevant length and\ntime scales. However, simulations face the problem that nucleation is an\nactivated process. Therefore, rare event simulation techniques are needed to\npromote the formation of the critical nucleus. The Seeding method, where the\nsimulations are started with the nucleus already formed, has proven quite\nuseful in efficiently providing estimates of the nucleation rate for a wide\nrange of orders of magnitude. So far, Seeding has been employed in the NPT\nensemble, where the nucleus either grows or redissolves. Thus, several\ntrajectories have to be run in order to find the thermodynamic conditions that\nmake the seeded nucleus critical. Moreover, the nucleus lifetime is short and\nthe statistics for obtaining its properties is consequently poor. To deal with\nthese shortcomings we extend the Seeding method to the NVT ensemble. We focus\non the problem of bubble nucleation in a mestastable Lennard Jones fluid. We\nshow that, in the NVT ensemble, it is possible to equilibrate and stabilise\ncritical bubbles for a long time. The nucleation rate inferred from NVT-Seeding\nis fully consistent with that coming from NPT-Seeding. The former is quite\nsuitable to obtain the nucleation rate along isotherms, whereas the latter is\npreferable if the dependence of the rate with temperature at constant pressure\nis required. Care should be taken with finite size effects when using\nNVT-Seeding. Further work is required to extend NVT seeding to other sorts of\nphase transitions."
    },
    {
        "anchor": "Structural properties and liquid spinodal of water confined in a\n  hydrophobic environment: We present the results of a computer simulation study of thermodynamical\nproperties of TIP4P water confined in a hydrophobic disordered matrix of soft\nspheres upon supercooling. The hydrogen bond network of water appears preserved\nin this hydrophobic confinement. Nonetheless a reduction in the average number\nof hydrogen bonds due to the geometrical constraints is observed. The liquid\nbranch of the spinodal line is calculated from 350 K down to 210 K. The same\nthermodynamic scenario of the bulk is found: the spinodal curve is\nmonotonically decreasing. The line of maximum density bends avoiding a crossing\nof the spinodal. There is however a shift both of the line of maximum density\nand of the spinodal toward higher pressures and lower temperatures with respect\nto bulk.",
        "positive": "Knotting of linear DNA in nano-slits and nano-channels: a numerical\n  study: The amount and type of self-entanglement of DNA filaments is significantly\naffected by spatial confinement, which is ubiquitous in biological systems.\nMotivated by recent advancements in single DNA molecule experiments based on\nnanofluidic devices, and by the introduction of algorithms capable of detecting\nknots in open chains, we investigate numerically the entanglement of linear,\nopen DNA chains confined inside nano-slits. The results regard the abundance,\ntype and length of occurring knots and are compared with recent findings for\nDNA inside nano-channels. In both cases, the width of the confining region, D,\nspans the 30nm- 1\\mu m range and the confined DNA chains are 1 to 4\\mu m long.\nIt is found that the knotting probability is maximum for slit widths in the\n70-100nm range. However, over the considered DNA contour lengths, the maximum\nincidence of knots remains below 20%, while for channel confinement it tops\n50%. Further differences of the entanglement are seen for the average contour\nlength of the knotted region which drops significantly below D ~100nm for\nchannel-confinement, while it stays approximately constant for slit-like\nconfinement. These properties ought to reverberate in different kinetic\nproperties of linear DNA depending on confinement and could be detectable\nexperimentally or exploitable in nano-technological applications."
    },
    {
        "anchor": "Fatigue and Collapse of Cyclically Bent Strip of Amorphous Solid: Fatigue caused by cyclic bending of a piece of material, resulting in its\nmechanical failure, is a phenomenon that had been studied for ages by engineers\nand physicists alike. In this Letter we study such fatigue in a strip of\nathermal amorphous solid. On the basis of atomistic simulations we conclude\nthat the crucial quantity to focus on is the {\\em accumulated damage}. Although\nthis quantity exhibits large sample-to-sample fluctuations, its dependence on\nthe loading determines the statistics of the number of cycles to failure. Thus\nwe can provide a scaling theory for the W\\\"ohler plots of mean number of cycles\nfor failure as a function of the loading amplitude.",
        "positive": "Theoretical model of viscous friction inside steadily sheared foams and\n  concentrated emulsions: In a recent letter (Denkov et al., Phys. Rev. Lett., vol. 100 (2008) p.\n138301) we calculated theoretically the macroscopic viscous stress of steadily\nsheared foam/emulsion from the energy dissipated inside the transient planar\nfilms, formed between neighboring bubbles/drops in the shear flow. The model\npredicts that the viscous stress in these systems should be a proportional to\nCa^1/2, where Ca is the capillary number and n = 1/2 is the power-law index. In\nthe current paper we explain in detail our model and develop it further in\nseveral aspects: First, we extend the model to account for the effects of\nviscous friction in the curved meniscus regions, surrounding the planar films,\non the dynamics of film formation and on the total viscous stress. Second, we\nconsider the effects of surface forces (electrostatic, van der Waals, etc.)\nacting between the surfaces of the neighboring bubbles/drops and show that\nthese forces could be important in emulsions, due to the relatively small\nthickness of emulsion films (often comparable to the range of action of the\nsurface forces). Third, additional consideration is made for bubbles/drops\nexhibiting high surface viscosity, for which we demonstrate an additional\ncontribution to the macroscopic viscous stress, created by the surface\ndissipation of energy. The new upgraded model predicts that the energy\ndissipation at the bubble/drop surface leads to power-law index n < 1/2,\nwhereas the contribution of the surface forces leads to n > 1/2, which explains\nthe rich variety of foam/emulsion behaviors observed upon steady shear. Various\ncomparisons are made between model predictions and experimental results for\nboth foams and emulsions, and a very good agreement is found."
    },
    {
        "anchor": "Tunable failure: control of rupture through rigidity: We investigate how material rigidity acts as a key control parameter for the\nfailure of solids under stress. In both experiments and simulations, we\ndemonstrate that material failure can be continuously tuned by varying the\nunderlying rigidity of the material while holding the amount of disorder\nconstant. As the rigidity transition is approached, failure due to the\napplication of uniaxial stress evolves from brittle cracking to system-spanning\ndiffuse breaking. This evolution in failure behavior can be parameterized by\nthe width of the crack. As a system becomes more and more floppy, this crack\nwidth increases until it saturates at the system size. Thus, the spatial extent\nof the failure zone can be used as a direct probe for material rigidity.",
        "positive": "Comment on \"Novel Convective Instabilities in a Magnetic Fluid\": Comment on the paper \"Novel Convective Instabilities in a Magnetic Fluid\" by\nW. Luo, T. Du, and J. Huang, Phys. Rev. Lett., v.82, p.4134 (1999)."
    },
    {
        "anchor": "Molecular dynamics study of the thermal conductivity in nanofluids: We evaluate the thermal conductivity of a model nanofluid at various volume\nfractions of nanoparticles with equilibrium (EMD) and non-equilibrium (NEMD)\nmolecular dynamics simulations. The Green-Kubo formalism is used for the EMD\nsimulations while a net heat flux is imposed on the system for the NEMD\nsimulations. The nanoparticle-nanoparticle, fluid-fluid and fluid-nanoparticle\ninteractions are all taken as Lennard-Jones potentials. An empirical parameter\nis added to the attractive part of the potential to control the hydrophilicity\nof the nanoparticles, hence controlling how well dispersed are the\nnanoparticles in the base fluid. The results show that the aggregation of the\nnanoparticles does not have a measurable effect on the conductivity of the\nnanofluid. Nanofluids with volume fractions of 2% and 3% show an enhanced\nconductivity with respect to the bulk fluid. Surprisingly, nanofluids with\nhigher volume fractions did not show any enhancement of the conductivity.",
        "positive": "Structural properties of the Jagla fluid: The structural properties of the Jagla fluid are studied by Monte Carlo (MC)\nsimulations, numerical solutions of integral equation theories, and the\n(semi-analytical) rational-function approximation (RFA) method. In the latter\ncase, the results are obtained from the assumption (supported by our MC\nsimulations) that the Jagla potential and a potential with a hard core plus an\nappropriate piecewise constant function lead to practically the same cavity\nfunction. The predictions obtained for the radial distribution function,\n$g(r)$, from this approach are compared against MC simulations and integral\nequations for the Jagla model, and also for the limiting cases of the\ntriangle-well potential and the ramp potential, with a general good agreement.\nThe analytical form of the RFA in Laplace space allows us to describe the\nasymptotic behavior of $g(r)$ in a clean way and compare it with MC simulations\nfor representative states with oscillatory or monotonic decay. The RFA\npredictions for the Fisher--Widom and Widom lines of the Jagla fluid are\nobtained."
    },
    {
        "anchor": "Statistics of a 2D immersed granular gas magnetically forced in volume: We present an experimental study of the dynamics of a set of magnets within a\nfluid in which a remote torque applied by a vertical oscillating magnetic field\ntransfers angular momentum to individual magnets. This system differs from\nprevious experimental studies of granular gas where the energy is injected by\nvibrating the boundaries. Here, we do not observe any cluster formation,\norientational correlation and equipartition of the energy. The magnets' linear\nvelocity distributions are stretched exponentials, similar to 3D\nboundary-forced dry granular gas systems, but the exponent does not depend on\nthe number of magnets. The value of the exponent of the stretched exponential\ndistributions is close to the value of 3/2 previously derived theoretically.\nOur results also show that the conversion rate of angular momentum into linear\nmomentum during the collisions controls the dynamics of this\nhomogenously-forced granular gas. We report the differences between this\nhomogeneously-forced granular gas, ideal gas, and nonequilibrium\nboundary-forced dissipative granular gas.",
        "positive": "Front-mediated melting of ultrastable glasses: Ultrastable vapor-deposited glasses display uncommon material properties.\nMost remarkably, upon heating they are believed to melt via a liquid front that\noriginates at the free surface and propagates over a mesoscopic crossover\nlength, before crossing over to bulk melting. We combine swap Monte Carlo with\nmolecular dynamics simulations to prepare and melt isotropic amorphous films of\nunprecedendtly high kinetic stability. We are able to directly observe both\nbulk and front melting, and the crossover between them. We measure the front\nvelocity over a broad range of conditions, and a crossover length scale that\ngrows to nearly $400$ particle diameters in the regime accessible to\nsimulations. Our results disentangle the relative roles of kinetic stability\nand vapor deposition in the physical properties of stable glasses."
    },
    {
        "anchor": "Well defined transition to gel-like aggregates of attractive athermal\n  particles: In an attempt to extend the range of model jamming transitions, we simulate\nsystems of athermal particles which attract when slightly overlapping.\nFollowing from recent work on purely repulsive systems, dynamics are neglected\nand relaxation performed via a potential energy minimisation algorithm. Our\ncentral finding is of a transition to a low-density tensile solid which is\nsharp in the limit of infinite system size. The critical density depends on the\nrange of the attractive regime in the pair-potential. Furthermore, solidity is\nshown to be related to the coordination number of the packing according to the\napproximate constraint-counting scheme known as Maxwell counting, although more\ncorrections need to be considered than with the repulsive-only case, as\nexplained. We finish by discussing how the numerical difficulties encountered\nin this work could be overcome in future studies.",
        "positive": "Splitting in the Excitation Spectrum of A Bose-Einstein Condensate\n  Undergoing Strong Rabi Oscillations: We report on a measurement of splitting in the excitation spectrum of a\ncondensate driven by an optical travelling wave. Experimental results are\ncompared to a numerical solution of the Gross Pitaevskii equation, and analyzed\nby a simple two level model and by the more complete band theory, treating the\ndriving beams as an optical lattice. In this picture, the splitting is a\nmanifestation of the energy gap between neighboring bands that opens on the\nboundary of the Brillouin zone."
    },
    {
        "anchor": "Stable nematic droplets with handles: We stabilize nematic droplets with handles against surface-tension-driven\ninstabilities using a yield-stress material as outer fluid and study the\ncomplex nematic textures and defect structures that result from the competition\nbetween topological constraints and the elasticity of the nematic liquid\ncrystal. We uncover a surprisingly persistent twisted configuration of the\nnematic director inside the droplets when tangential anchoring is established\nat their boundaries, which we explain after considering the influence of\nsaddle-splay on the elastic free energy. For toroidal droplets, we find that\nthe saddle-splay energy screens the twisting energy resulting in a spontaneous\nbreaking of mirror symmetry; the chiral twisted state persists for aspect\nratios as large as ~20. For droplets with additional handles, we observe in\nexperiments and computer simulations that there are two additional -1 surface\ndefects per handle; these are located in regions with local saddle geometry to\nminimize the nematic distortions and hence the corresponding elastic free\nenergy.",
        "positive": "Shear-induced organization of forces in dense suspensions: signatures of\n  discontinuous shear thickening: Dense suspensions can exhibit an abrupt change in their viscosity in response\nto increasing shear rate. The origin of this discontinuous shear thickening\n(DST) has been ascribed to the transformation of lubricated contacts to\nfrictional, particle-on-particle contacts. Recent research on the flowing and\njamming behavior of dense suspensions has explored the intersection of ideas\nfrom granular physics and Stokesian fluid dynamics to better understand this\ntransition from lubricated to frictional rheology. DST is reminiscent of\nclassical phase transitions, and a key question is how interactions between the\nmicroscopic constituents give rise to a macroscopic transition. In this paper,\nwe extend a formalism that has proven to be successful in understanding shear\njamming of dry grains to dense suspensions. Quantitative analysis of the\ncollective evolution of the contact-force network accompanying the DST\ntransition demonstrates clear changes in the distribution of microscopic\nvariables, and leads to the identification of an \"order parameter\"\ncharacterizing DST."
    },
    {
        "anchor": "Collective Variables for Crystallization Simulations -- from Early\n  Developments to Recent Advances: Crystallization is one of the most important physicochemical processes which\nhas relevance in material science, biology, and the environment. Decades of\nexperimental and theoretical efforts have been made to understand this\nfundamental symmetry-breaking transition. While experiments provide equilibrium\nstructures and shapes of crystals, they are limited to unraveling how molecules\naggregate to form crystal nuclei that subsequently transform into bulk\ncrystals. Computer simulations, mainly molecular dynamics (MD), can provide\nsuch microscopic details during the early stage of a crystallization event.\nCrystallization is a rare event that takes place in timescales much longer than\na typical equilibrium MD simulation can sample. This inadequate sampling of the\nMD method can be easily circumvented by the use of enhanced sampling (ES)\nsimulations. An ES method enhances the fluctuations of a system's slow degrees\nof freedom, called collective variables (CVs), by applying a bias potential,\nand thereby transforms the system from one state to the other within a short\ntimescale. The most crucial part of an ES method is to find suitable CVs which\noften needs intuition and several trial-and-error optimization steps. Over the\nyears, a plethora of CVs has been developed and applied in the study of\ncrystallization. In this review, we provide a brief overview of CVs that have\nbeen developed and used in ES simulations to study crystallization from melt or\nsolution. These CVs can be categorized mainly into four types: (i) spherical\nparticle-based, (ii) molecular template-based, (iii) physical property-based,\nand (iv) CVs obtained from dimensionality reduction techniques. We present the\ncontext-based evolution of CVs, discuss the current challenges, and propose\nfuture directions to further develop effective CVs for the study of\ncrystallization of complex systems.",
        "positive": "Understanding the Salt Effects on the Liquid-Liquid Phase Separation of\n  Proteins: Protein aggregation via liquid-liquid phase separation (LLPS) is ubiquitous\nin nature and intimately connects to many human diseases. Although it is widely\nknown that the addition of salt has crucial impacts on the LLPS of protein,\nfull understanding of the salt effect remains an outstanding challenge. Here,\nwe develop a molecular theory which systematically incorporates the\nself-consistent field theory for charged macromolecules into the solution\nthermodynamics. The electrostatic interaction, hydrophobicity, ion solvation\nand translational entropy are included in a unified framework. Our theory fully\ncaptures the long-standing puzzles of the non-monotonic salt concentration\ndependence and the specific ion effect. We find that proteins show salting-out\nat low salt concentrations due to ionic screening. The solubility follows the\ninverse Hofmeister series. In the high salt concentration regime, protein\nremains salting-out for small ions but turns to salting-in for larger ions,\naccompanied by the reversal of the Hofmeister series. We reveal that the\nsolubility at high salt concentrations is determined by the competition between\nthe solvation energy and translational entropy of ion. Furthermore, we derive\nan analytical criterion for determining the boundary between the salting-in and\nsalting-out regimes. The theoretical prediction is in quantitative agreement\nwith experimental results for various proteins and salt ions without any\nfitting parameters."
    },
    {
        "anchor": "Polar In-Plane Surface Orientation of a Ferroelectric Nematic Liquid\n  Crystal: Polar Monodomains and Twisted State Electro-Optics: We show that surface interactions can vectorially structure the\nthree-dimensional polariza-tion field of a ferroelectric fluid. The contact\nbetween a ferroelectric nematic liquid crystal and a surface with in-plane\npolarity generates a preferred in-plane orientation of the polarization field\nat that interface. This is a route to the formation of fluid or glassy\nmonodomains of high polarization without the need for electric field poling.\nFor example, unidirectional buffing of polyimide films on planar surfaces to\ngive quadrupolar in-plane anisotropy also induces mac-roscopic in-plane polar\norder at the surfaces, enabling the formation of a variety of azimuthal polar\ndirector structures in the cell interior, including uniform and twisted states.\nIn a {\\pi}-twist cell, obtained with antiparallel, unidirectional buffing on\nopposing surfaces, we demonstrate three distinct modes of ferroelectric nematic\nelectro-optic response: intrinsic, viscosity-limited, field-induced molecular\nreorientation; field-induced motion of domain walls separating twist-ed states\nof opposite chirality; and propagation of polarization reorientation solitons\nfrom the cell plates to the cell center upon field reversal. Chirally doped\nferroelectric nematics in anti-parallel-rubbed cells produce Grandjean textures\nof helical twist that can be unwound via field-induced polar surface\nreorientation transitions. Fields required are in the 3 V/mm range, indicating\nan in-plane polar anchoring energy of wP ~ 3x10-3 J/m2.",
        "positive": "Designer Pair Statistics of Disordered Many-Particle Systems with Novel\n  Properties: Knowledge of exact analytical functional forms for the pair correlation\nfunction $g_2(r)$ and its corresponding structure factor $S(k)$ of disordered\nmany-particle systems is limited. For fundamental and practical reasons, it is\nhighly desirable to add to the existing data base of analytical functional\nforms for such pair statistics. Here, we design a plethora of such pair\nfunctions in direct and Fourier spaces across the first three Euclidean space\ndimensions that are realizable by diverse many-particle systems with varying\ndegrees of correlated disorder across length scales, spanning a wide spectrum\nof hyperuniform, typical nonhyperuniform and antihyperuniform ones. This is\naccomplished by utilizing an efficient inverse algorithm that determines\nequilibrium states with up to pair interactions at positive temperature that\nprecisely match targeted forms for both $g_2(r)$ and $S(k)$. Among other\nresults, we realize an example with the strongest hyperuniform property among\nknown positive-temperature equilibrium states, critical-point systems (implying\nunusual 1D systems with phase transitions) that are not in the Ising\nuniversality class, systems that attain self-similar pair statistics under\nFourier transformation, and an experimentally feasible polymer model. We show\nthat our pair functions enable one to achieve systems with a wide range of\ntranslational order and self-diffusion coefficients $\\cal D$, which are\ninversely related to one another. One can design other realizable pair\nstatistics via linear combinations of our functions or by applying our inverse\nprocedure to other desirable functional forms. Our approach facilitates the\ninverse design of materials with desirable physical and chemical properties by\ntuning their pair statistics."
    },
    {
        "anchor": "Multiscale approaches to protein-mediated interactions between membranes\n  - Relating microscopic and macroscopic dynamics in radially growing adhesions: Macromolecular complexation leading to coupling of two or more cellular\nmembranes is a crucial step in a number of biological functions of the cell.\nWhile other mechanisms may also play a role, adhesion always involves the\nfluctuations of deformable membranes, the diffusion of proteins and the\nmolecular binding and unbinding. Because these stochastic processes couple over\na multitude of time and length scales, theoretical modeling of membrane\nadhesion has been a major challenge. Here we present an effective Monte Carlo\nscheme within which the effects of the membrane are integrated into local rates\nfor molecular recognition. The latter step in the Monte Carlo approach enables\nus to simulate the nucleation and growth of adhesion domains within a system of\nthe size of a cell for tens of seconds without loss of accuracy, as shown by\ncomparison to $10^6$ times more expensive Langevin simulations. To perform this\nvalidation, the Langevin approach was augmented to simulate diffusion of\nproteins explicitly, together with reaction kinetics and membrane dynamics. We\nuse the Monte Carlo scheme to gain deeper insight to the experimentally\nobserved radial growth of micron sized adhesion domains, and connect the\neffective rate with which the domain is growing to the underlying microscopic\nevents. We thus demonstrate that our technique yields detailed information\nabout protein transport and complexation in membranes, which is a fundamental\nstep toward understanding even more complex membrane interactions in the\ncellular context.",
        "positive": "Morphogenesis of filaments growing in flexible confinements: Space-saving design is a requirement that is encountered in biological\nsystems and the development of modern technological devices alike. Many living\norganisms dynamically pack their polymer chains, filaments or membranes inside\nof deformable vesicles or soft tissue like cell walls, chorions, and buds.\nSurprisingly little is known about morphogenesis due to growth in flexible\nconfinements - perhaps owing to the daunting complexity lying in the nonlinear\nfeedback between packed material and expandable cavity. Here we show by\nexperiments and simulations how geometric and material properties lead to a\nplethora of morphologies when elastic filaments are growing far beyond the\nequilibrium size of a flexible thin sheet they are confined in. Depending on\nfriction, sheet flexibility and thickness, we identify four distinct\nmorphological phases emerging from bifurcation and present the corresponding\nphase diagram. Four order parameters quantifying the transitions between these\nphases are proposed."
    },
    {
        "anchor": "Hydrodynamic stress maps on the surface of a flexible fin-like foil: We determine the time dependence of pressure and shear stress distributions\non the surface of a pitching and deforming hydrofoil from measurements of the\nthree dimensional flow field. Period-averaged stress maps are obtained both in\nthe presence and absence of steady flow around the foil. The velocity vector\nfield is determined via volumetric three-component particle tracking\nvelocimetry and subsequently inserted into the Navier-Stokes equation to\ncalculate the total hydrodynamic stress tensor. In addition, we also present a\ncareful error analysis of such measurements, showing that local evaluations of\nstress distributions are possible. The flapping foil used in the experiments is\ndesigned to allow comparison with a small trapezoidal fish fin, in terms of the\nscaling laws that govern the oscillatory flow regime. Unsteady Euler-Bernoulli\nbeam theory is employed to derive instantaneous transversal force distributions\non the deflecting hydrofoil from its deflection and thereby validate the\nspatial distributions of hydrodynamic stresses obtained from the fluid velocity\nfield. The consistency of the force time-dependence is verified using a control\nvolume analysis.",
        "positive": "Laser microfluidics: fluid actuation by light: The development of microfluidic devices is still hindered by the lack of\nrobust fundamental building blocks that constitute any fluidic system. An\nattractive approach is optical actuation because light field interaction is\ncontactless and dynamically reconfigurable, and solutions have been anticipated\nthrough the use of optical forces to manipulate microparticles in flows.\nFollowing the concept of an 'optical chip' advanced from the optical actuation\nof suspensions, we propose in this survey new routes to extend this concept to\nmicrofluidic two-phase flows. First, we investigate the destabilization of\nfluid interfaces by the optical radiation pressure and the formation of liquid\njets. We analyze the droplet shedding from the jet tip and the continuous\ntransport in laser-sustained liquid channels. In the second part, we\ninvestigate a dissipative light-flow interaction mechanism consisting in\nheating locally two immiscible fluids to produce thermocapillary stresses along\ntheir interface. This opto-capillary coupling is implemented in adequate\nmicrochannel geometries to manipulate two-phase flows and propose a contactless\noptical toolbox including valves, droplet sorters and switches, droplet\ndividers or droplet mergers. Finally, we discuss radiation pressure and\nopto-capillary effects in the context of the 'optical chip' where flows,\nchannels and operating functions would all be performed optically on the same\ndevice."
    },
    {
        "anchor": "A Nonlinear Boundary Condition for Continuum Models of Biomolecular\n  Electrostatics: Understanding the behavior of biomolecules such as proteins requires\nunderstanding the critical influence of the surrounding fluid (solvent)\nenvironment--water with mobile salt ions such as sodium. Unfortunately, for\nmany studies, fully atomistic simulations of biomolecules, surrounded by\nthousands of water molecules and ions are too computationally slow. Continuum\nsolvent models based on macroscopic dielectric theory (e.g. the Poisson\nequation) are popular alternatives, but their simplicity fails to capture\nwell-known phenomena of functional significance. For example, standard theories\npredict that electrostatic response is symmetric with respect to the sign of an\natomic charge, even though response is in fact strongly asymmetric if the\ncharge is near the biomolecule surface. In this work, we present an asymmetric\ncontinuum theory that captures the essential physical mechanism--the finite\nsize of solvent atoms--using a nonlinear boundary condition (NLBC) at the\ndielectric interface between the biomolecule and solvent. Numerical\ncalculations using boundary-integral methods demonstrate that the new NLBC\nmodel reproduces a wide range of results computed by more realistic, and\nexpensive, all-atom molecular-dynamics (MD) simulations in explicit water. We\ndiscuss model extensions such as modeling dilute-electrolyte solvents with\nDebye-Huckel theory (the linearized Poisson-Boltzmann equation) and\nopportunities for the electromagnetics community to contribute to research in\nthis important area of molecular nanoscience and engineering.",
        "positive": "Helical buckling in columnar assemblies of soft discotic mesogens: We investigate the emergence of chiral meso-structures in one-dimensional\nfluids consisting of stacked discotic particles and demonstrate that helical\nundulations are generated spontaneously from internal elastic stresses. The\nstability of these helical conformations arises from an interplay between\nlong-ranged soft repulsions and nanopore confinement which is naturally present\nin columnar liquid crystals. Using a simple mean-field theory based on\nmicroscopic considerations we identify generic scaling expressions for the\ntypical buckling radius and helical pitch as a function of the density and\ninteraction potential of the constituent particles."
    },
    {
        "anchor": "Global structure of Bose-Einstein condensates at high rotation: Beyond\n  the lowest Landau level description: We study the global density profile of a rapidly rotating Bose-Einstein\ncondensate in a harmonic trap with transverse frequency $\\omega_{\\perp}$. By\nintroducing an additional variational degree of freedom to the lowest Landau\nlevel wave function, we demonstrate that with increasing strength of the\ninterparticle interaction, the global density profile changes from a Gaussian\nto the inverted parabolic one characteristic of Thomas-Fermi theory. The\ncriterion for the lowest Landau level wave function to be a good approximation\nfor the global structure is that the mean field energy be small compared with\n$\\hbar \\omega_{\\perp}/N_{\\rm v}$, where $N_{\\rm v}$ is the number of vortices\nin the cloud. This condition is more stringent than the requirement that the\nmean field energy be small compared with $\\hbar \\omega_{\\perp}$ which is\nnecessary for the lowest Landau level wave function to be a good approximation\nto the local structure. Our results show that the lowest Landau level wave\nfunction is inappropriate for the global structure of the system realized in\nrecent experiments even though this wave function can describe the local\nstructure well.",
        "positive": "Beliaev damping of quasi-particles in a Bose-Einstein condensate: We report a measurement of the suppression of collisions of quasi-particles\nwith ground state atoms within a Bose-Einstein condensate at low momentum.\nThese collisions correspond to Beliaev damping of the excitations, in the\npreviously unexplored regime of the continuous quasi-particle energy spectrum.\nWe use a hydrodynamic simulation of the expansion dynamics, with the Beliaev\ndamping cross-section, in order to confirm the assumptions of our analysis."
    },
    {
        "anchor": "Fluctuations can induce local nematic order and extensile stress in\n  monolayers of motile cells: Recent experiments in various cell types have shown that two-dimensional\ntissues often display local nematic order, with evidence of extensile stresses\nmanifest in the dynamics of topological defects. Using a mesoscopic model where\ntissue flow is generated by fluctuating traction forces coupled to the nematic\norder parameter, we show that the resulting tissue dynamics can spontaneously\nproduce local nematic order and an extensile internal stress. A key element of\nthe model is the assumption that in the presence of local nematic alignment,\ncells preferentially crawl along the nematic axis, resulting in anisotropy of\nfluctuations. Our work shows that activity can drive either extensile or\ncontractile stresses in tissue, depending on the relative strength of the\ncontractility of the cortical cytoskeleton and tractions by cells on the\nextracellular matrix.",
        "positive": "Separation and fractionation of order and disorder in highly\n  polydisperse systems: Microcanonical Monte Carlo simulations of a polydisperse soft-spheres model\nfor liquids and colloids have been performed for very large polydispersity, in\nthe region where a phase-separation is known to occur when the system (or part\nof it) solidifies. By studying samples of different sizes, from N=256 to N=864,\nwe focus on the nature of the two distinct coexisting phases. Measurements of\ncrystalline order in particles of different size reveal that the solid phase\nsegregates between a crystalline solid with cubic symmetry and a disordered\nphase. This phenomenon is termed fractionation."
    },
    {
        "anchor": "Long-wavelength fluctuations and anomalous dynamics in two-dimensional\n  liquids: Long-wavelength Mermin-Wagner fluctuations prevent the existence of\ntranslational long-range order, in two-dimensional systems at finite\ntemperature. Their dynamical signature, which is the divergence of the\nvibrational amplitude with the system size, also affects disordered solids and\nwashes out the transient solid-like response generally exhibited by liquids\ncooled below their melting temperature. Through a combined numerical and\nexperimental investigation, here we show that long-wavelength fluctuations are\nalso relevant at high temperature, where the liquid dynamics does not reveal a\ntransient solid-like response. In this regime, they induce an unusual but\nubiquitous decoupling between long-time diffusion coefficient $D$ and\nstructural relaxation time $\\tau$, where $D\\propto \\tau^{-\\kappa}$, with\n$\\kappa > 1$. Long-wavelength fluctuations have a negligible influence on the\nrelaxation dynamics only at extremely high temperatures, in molecular liquids,\nor extremely low densities, in colloidal systems.",
        "positive": "Alignment and alignment dynamics of nematic liquid crystals on\n  Langmuir-Blodgett mono-layers: Mono-layers of stearic and behenic acids deposited with the Langmuir-Blodgett\ntechnique, were used as aligning films in nematic liquid crystal cells. During\nthe filling process the liquid crystal adopts a deformed quasi-planar alignment\nwith splay-bend deformation and preferred orientation along the filling\ndirection. This state is metastable and transforms with time into homeotropic\nonce the flow has ceased. The transition is accompanied by formation of\ndisclination lines which nucleate at the edges of the cell. The lifetime of the\nmetastable splay-bend state was found to depend on the cell thickness. On\nheating, anchoring transition from quasi-homeotropic to degenerate tilted\nalignment in form of circular domains takes place near the transition to the\nisotropic phase. The anchoring transition is reversible with a small\nhysteresis."
    },
    {
        "anchor": "Folding Kinetics of a Polymer: By simulating the first order globule-crystal transition of a flexible\nhomopolymer chain, both by collision dynamics and Monte Carlo with non-kinetic\nmoves, we show that the effective and the thermodynamic transition temperatures\nare different and we propose a way of quantifying the kinetic hindering. We\nthen also observe that the top eigenvalue in the spectrum of the dynamical\n(contact or adjacency) matrix provides insight into the ensembles of folding\nand unfolding trajectories, and may be a suitable additional reaction\ncoordinate for the folding transition of chain molecules.",
        "positive": "Metastability on the steady states in a Fermi-like model of\n  counterflowing particles: In this work we propose a two-dimensional extension of a previously defined\none-dimensional version of a model of counterflowing particles, which considers\nan adapted Fermi-Dirac distribution to describe the transition probabilities.\nIn this modified and extended version of the model, we consider that only\nparticles of different species interact and they hop through the cells of a two\ndimensional rectangular lattice with probabilities taking into account\ndiffusive and scattering aspects. We show that for a sufficiently low level of\nrandomness ($\\alpha \\geq 10$), the system can relax to a mobile self-organized\nsteady state of counterflow (lane formation) or to an immobile state (clog)\ndepending sensitively on the initial conditions if the system has an average\ndensity near the crossover value ($\\rho _{c}$). We also show that for certain\nsuitable mixing of the species, we peculiarly have 3 different situations: (i)\nThe immobile,(ii) Mobile organized by lanes, and (iii) Mobile without lane\nformation for the same density value. All of our results were obtained by\nperforming Monte Carlo simulations."
    },
    {
        "anchor": "Counterion Condensation and Fluctuation-Induced Attraction: We consider an overall neutral system consisting of two similarly charged\nplates and their oppositely charged counterions and analyze the electrostatic\ninteraction between the two surfaces beyond the mean-field Poisson-Boltzmann\napproximation. Our physical picture is based on the fluctuation-driven\ncounterion condensation model, in which a fraction of the counterions is\nallowed to ``condense'' onto the charged plates. In addition, an expression for\nthe pressure is derived, which includes fluctuation contributions of the whole\nsystem. We find that for sufficiently high surface charges, the distance at\nwhich the attraction, arising from charge fluctuations, starts to dominate can\nbe large compared to the Gouy-Chapmann length. We also demonstrate that\ndepending on the valency, the system may exhibit a novel first-order binding\ntransition at short distances.",
        "positive": "Jamming under tension in polymer crazes: Molecular dynamics simulations are used to study a unique expanded jammed\nstate. Tension transforms many glassy polymers from a dense glass to a network\nof fibrils and voids called a craze. Entanglements between polymers and\ninterchain friction jam the system after a fixed increase in volume. As in\ndense jammed systems, the distribution of forces is exponential, but they are\ntensile rather than compressive. The broad distribution of forces has important\nimplications for fibril breakdown and the ultimate strength of crazes."
    },
    {
        "anchor": "Elastic wave propagation in simple-sheared hyperelastic materials with\n  different constitutive models: We investigate the elastic wave propagation in various hyperelastic materials\nwhich subjected to simple-shear deformation. Two compressible types of three\nconventional hyperelastic models are considered. We found pure elastic wave\nmodes can be obtained in compressible neo-Hookean materials constructed by\nadding a bulk strain energy term to the incompressible strain energy function.\nWhereas for the compressible hyperelastic models which are reformulate into\ndeviatoric and hydrostatic parts, only quasi modes can propagate, with abnormal\nray directions can be observed for longitudinal waves. Moreover, the influences\nof material constants, material compressibility and external deformations on\nthe propagation and refraction for elastic waves in these hyperelastic models\nare systematically studied. Numerical simulations are carried out to validate\nthe theoretical results. This investigation may open a promising route for the\nrealization of next generation metamaterials and novel wave manipulation\ndevices.",
        "positive": "Equilibrium swelling and universal ratios in dilute polymer solutions:\n  Exact Brownian dynamics simulations for a delta function excluded volume\n  potential: A narrow Gaussian excluded volume potential, which tends to a delta-function\nrepulsive potential in the limit of a width parameter d* going to zero, has\nbeen used to examine the universal consequences of excluded volume interactions\non the equilibrium and linear viscoelastic properties of dilute polymer\nsolutions. Brownian dynamics simulations data, acquired for chains of finite\nlength, has been extrapolated to the limit of infinite chain length to obtain\nmodel independent predictions. The success of the method in predicting well\nknown aspects of static solution properties suggests that it can be used as a\nsystematic means by which the influence of solvent quality on both equilibrium\nand non-equilibrium properties can be studied."
    },
    {
        "anchor": "Multiparameter actuation of a neutrally-stable shell: a flexible\n  gear-less motor: We have designed and tested experimentally a morphing structure consisting of\na neutrally stable thin cylindrical shell driven by a multiparameter\npiezoelectric actuation. The shell is obtained by plastically deforming an\ninitially flat copper disk, so as to induce large isotropic and almost uniform\ninelastic curvatures. Following the plastic deformation, in a perfectly\nisotropic system, the shell is theoretically neutrally stable, owning a\ncontinuous manifold of stable cylindrical shapes corresponding to the rotation\nof the axis of maximal curvature. Small imperfections render the actual\nstructure bistable, giving preferred orientations. A three-parameter\npiezoelectric actuation, exerted through micro-fiber-composite actuators,\nallows us to add a small perturbation to the plastic inelastic curvature and to\ncontrol the direction of maximal curvature. This actuation law is designed\nthrough a geometrical analogy based on a fully non-linear inextensible\nuniform-curvature shell model. We report on the fabrication, identification,\nand experimental testing of a prototype and demonstrate the effectiveness of\nthe piezoelectric actuators in controlling its shape. The resulting motion is\nan apparent rotation of the shell, controlled by the voltages as in a\n\"gear-less motor\", which is, in reality, a precession of the axis of principal\ncurvature.",
        "positive": "Stability of multiquantum vortices in dilute Bose-Einstein condensates: Multiply quantized vortices in trapped Bose-Einstein condensates are studied\nusing the Bogoliubov theory. Suitable combinations of a localized pinning\npotential and external rotation of the system are found to energetically\nstabilize, both locally and globally, vortices with multiple circulation\nquanta. We present a phase diagram for stable multiply quantized vortices in\nterms of the angular rotation frequency and the width of the pinning potential.\nWe argue that multiquantum vortices could be experimentally created using these\ntwo expedients."
    },
    {
        "anchor": "Flow-induced phase separation of active particles is controlled by\n  boundary conditions: Active particles, including swimming microorganisms, autophoretic colloids\nand droplets, are known to self-organize into ordered structures at fluid-solid\nboundaries. The entrainment of particles in the attractive parts of their\nspontaneous flows has been postulated as a possible mechanism underlying this\nphenomenon. Here, combining experiments, theory and numerical simulations, we\ndemonstrate the validity of this flow-induced ordering mechanism in a\nsuspension of active emulsion droplets. We show that the mechanism can be\ncontrolled, with a variety of resultant ordered structures, by simply altering\nhydrodynamic boundary conditions. Thus, for flow in Hele-Shaw cells, metastable\nlines or stable traveling bands can be obtained by varying the cell height.\nSimilarly, for flow bounded by a plane, dynamic crystallites are formed. At a\nno-slip wall the crystallites are characterised by a continuous out-of-plane\nflux of particles that circulate and re-enter at the crystallite edges, thereby\nstabilising them. At an interface where the tangential stress vanishes the\ncrystallites are strictly two-dimensional, with no out-of-plane flux. We\nrationalize these experimental results by calculating, in each case, the slow\nviscous flow produced by the droplets and the dissipative, long-ranged,\nmany-body active forces and torques between them. The results of numerical\nsimulations of motion under the action of the active forces and torques are in\nexcellent agreement with experiments. Our work elucidates the mechanism of\nflow-induced phase separation (FIPS) in active fluids, particularly active\ncolloidal suspensions, and demonstrates its control by boundaries, suggesting\nnew routes to geometric and topological phenomena in active matter.",
        "positive": "Cross-linking patterns and their images in swollen and deformed gels: Using the theory of elasticity of polymer gels we show that large-scale\ncross-link density patterns written into the structure of the network in the\nmelt state, can be revealed upon swelling by monitoring the monomer density\npatterns. We find that while isotropic deformations in good solvent yield\nmagnified images of the original pattern, anisotropic deformations distort the\nimage (both types of deformation yield affinely stretched images in $\\theta$\nsolvents). We show that in ordinary solids with spatially inhomogeneous profile\nof the shear modulus, isotropic stretching leads to distorted density image of\nthis profile under isotropic deformation. Using simple physical arguments we\ndemonstrate that the different response to isotropic stretching stems from\nfundamental differences between the theory of elasticity of solids and that of\ngels. Possible tests of our predictions and some potential applications are\ndiscussed."
    },
    {
        "anchor": "Slip behavior in liquid films on surfaces of patterned wettability:\n  Comparison between continuum and molecular dynamics simulations: We investigate the behavior of the slip length in Newtonian liquids subject\nto planar shear bounded by substrates with mixed boundary conditions. The upper\nwall, consisting of a homogenous surface of finite or vanishing slip, moves at\na constant speed parallel to a lower stationary wall, whose surface is\npatterned with an array of stripes representing alternating regions of no-shear\nand finite or no-slip. Velocity fields and effective slip lengths are computed\nboth from molecular dynamics (MD) simulations and solution of the Stokes\nequation for flow configurations either parallel or perpendicular to the\nstripes. Excellent agreement between the hydrodynamic and MD results is\nobtained when the normalized width of the slip regions, $a/\\sigma \\gtrsim {\\cal\nO}(10)$, where $\\sigma$ is the (fluid) molecular diameter characterizing the\nLennard-Jones interaction. In this regime, the effective slip length increases\nmonotonically with $a/\\sigma$ to a saturation value. For $a/\\sigma \\lesssim\n{\\cal O}(10)$ and transverse flow configurations, the non-uniform interaction\npotential at the lower wall constitutes a rough surface whose molecular scale\ncorrugations strongly reduce the effective slip length below the hydrodynamic\nresults. The translational symmetry for longitudinal flow eliminates the\ninfluence of molecular scale roughness; however, the reduced molecular ordering\nabove the wetting regions of finite slip for small values of $a/\\sigma$\nincreases the value of the effective slip length far above the hydrodynamic\npredictions. The strong inverse correlation between the effective slip length\nand the liquid structure factor representative of the first fluid layer near\nthe patterned wall illustrates the influence of molecular ordering effects on\nslip in non-inertial flows.",
        "positive": "Reversible stepwise condensation polymerization with cyclization:\n  strictly alternating co-polymerization and homopolymerization based upon two\n  orthogonal reactions: In a preceding work [M. Lang, K. Kumar, A simple and general approach for\nreversible condensation polymerization with cyclization, Macromolecules 54\n(2021) 7021], we have introduced a simple recursive scheme that allows to treat\nstepwise linear reversible polymerizations of any kind with cyclization. This\napproach is used to discuss the polymerization of linear Gaussian strands (LGS)\nwith two different reactive groups $A$ and $B$ on either chain end that\nparticipate in two orthogonal reactions and the strictly alternating\ncopolymerization of LGS that carry $A$ reactive groups with LGS equipped with\ntype $B$ reactive groups. The former of these cases has not been discussed\ntheoretically in literature, the latter only regarding some special cases. We\nprovide either analytical expressions or exact numerical solutions for the\ngeneral cases with and without cyclization. Weight distributions, averages,\npolydispersity, and the weight fractions of cyclic and linear species are\ncomputed. All numerical solutions were tested by Monte-Carlo simulations."
    },
    {
        "anchor": "Langevin equations for the run-and-tumble of swimming bacteria: The run and tumble motions of a swimming bacterium are well characterized by\ntwo stochastic variables: the speed $v(t)$ and the change of direction or\ndeflection \\mbox{$x(t)=\\cos\\varphi(t)$}, where $\\varphi(t)$ is the turning\nangle at time $t$. Recently, we have introduced [Soft Matter {\\bf 13}, 3385\n(2017)] a single stochastic model for the deflection $x(t)$ of an {\\sl E. coli}\nbacterium performing both types of movement in isotropic media without taxis,\nbased on available experimental data. In this work we introduce Langevin\nequations for the variables $(v,x)$, which for particular values of a control\nparameter $\\beta$ correspond to run and tumble motions, respectively. These\nLangevin equations have analytical solutions, which make it possible to\ncalculate the statistical properties of both movements in detail. Assuming that\nthe stochastic processes $x$ and $v$ are not independent during the tumble, we\nshow that there are small displacements of the center of mass along the normal\ndirection to the axis of the bacterial body, a consequence of the flagellar\nunbundling during the run-to-tumble transition. Regarding the tumble we show,\nby means of the directional correlation, that the process is not stationary for\ntumble-times of the order of experimentally measured characteristic\ntumble-time. The mean square displacement is studied in detail for both\nmovements even in the non-stationary regime. We determine the diffusion and\nballistic coefficients for tumble- and run-times, establishing their properties\nand relationships.",
        "positive": "Encoding Microreactors with Droplet Chains in Microfluidics: Droplet-based high throughput biomolecular screening and combinatorial\nsynthesis entail a viable indexing strategy to be developed for the\nidentification of each micro-reactor. Here, we propose a novel indexing scheme\nbased on the generation of droplet sequences on demand to form unique encoding\ndroplet chains in fluidic networks. These codes are represented by multiunit\nand multilevel droplets packages, with each code unit possessing several\ndistinct signal levels, potentially allowing large encoding capacity. For proof\nof concept, we use magnetic nanoparticles as the encoding material and a giant\nmagnetoresistance (GMR) sensor-based active sorting system supplemented with an\noptical detector to generate and decode the sequence of one exemplar sample\ndroplet reactor and a 4-unit quaternary magnetic code. The indexing capacity\noffered by 4-unit multilevel codes with this indexing strategy is estimated to\nexceed 104, which holds great promise for large-scale droplet-based screening\nand synthesis."
    },
    {
        "anchor": "Escape configuration lattice near the nematic-isotropic transition: Tilt\n  analogue of blue phases: We predict the possible existence of a new phase of liquid crystals near the\nnematic-isotropic ($ NI $) transition. This phase is an achiral, tilt-analogue\nof the blue phase and is composed of a lattice of {\\em double-tilt},\nescape-configuration cylinders. We discuss the structure and the stability of\nthis phase and provide an estimate of the lattice parameter.",
        "positive": "Chiral Mesophases of DNA: In the hexagonal columnar phase of chiral polymers a bias towards cholesteric\ntwist competes with braiding along an average direction. When the chirality is\nstrong, topological defects proliferate, leading to either a tilt grain\nboundary phase or a new ``moire state'' with twisted bond order. This moire\nphase can melt leading to a new phase: the chiral hexatic. I will discuss some\nrecent experimental results from the NIH on DNA liquid crystals in the context\nof these theories."
    },
    {
        "anchor": "The incompressible limit in linear anisotropic elasticity, with\n  application to surface waves and elastostatics: Incompressibility is established for three-dimensional and two-dimensional\ndeformations of an anisotropic linearly elastic material, as conditions to be\nsatisfied by the elastic compliances. These conditions make it straightforward\nto derive results for incompressible materials from those established for the\ncompressible materials. As an illustration, the explicit secular equation is\nobtained for surface waves in incompressible monoclinic materials with the\nsymmetry plane at x_3=0. This equation also covers the case of incompressible\northotropic materials.\n  The displacements and stresses for surface waves are often expressed in terms\nof the elastic stiffnesses, which can be unbounded in the incompressible limit.\nAn alternative formalism in terms of the elastic compliances presented recently\nby Ting is employed so that surface wave solutions in the incompressible limit\ncan be obtained. A different formalism, also by Ting, is employed to study the\nsolutions to two-dimensional elastostatic problems.\n  In the special case of incompressible monoclinic material with the symmetry\nplane at x_3=0, one of the three Barnett-Lothe tensors S vanishes while the\nother two tensors H and L are the inverse of each other. Moreover, H and L are\ndiagonal with the first two diagonal elements being identical. An interesting\nphysical phenomenon deduced from this property is that there is no\ninterpenetration of the interface crack surface in an incompressible\nbimaterial. When only the inplane deformation is considered, it is shown that\nthe image force due to a line dislocation in a half-space or in a bimaterial\ndepends only on the magnitude, not on the direction, of the Burgers vector.",
        "positive": "A Monte Carlo simulation study on the wetting behavior of water on\n  graphite surface: This paper is an expanded edition of the rapid communication published\nseveral years ago by the author (Phys. Rev. B, v76, 041402(R), 2007) on the\nsimulation of wetting transition of water on graphite, aiming to provide more\ndetails on the methodology, parameters, and results of the study which might be\nof interest to certain readers. We calculate adsorption isotherms of water on\ngraphite using grand canonical Monte Carlo simulations combined with multiple\nhistogram reweighting, based on the empirical potentials of SPC/E for water,\nthe 10-4-3 van der Waals model, and a recently developed induction and\nmultipolar potential for water and graphite. Our results show that wetting\ntransition of water on graphite occurs at 475-480 K, and the prewetting\ncritical temperature lies in the range of 505-510 K. The calculated wetting\ntransition temperature agrees quantitatively with a previously predicted value\nusing a simple model. The observation of the coexistence of stable and\nmetastable states at temperatures between the wetting transition temperature\nand prewetting critical temperature indicates that the transition is first\norder."
    },
    {
        "anchor": "Thick smectic shells: The known ground state of ultrathin smectic films confined to the surface of\na sphere is described by four +1/2 defects assembled on a great circle and a\ndirector which follows geodesic lines. Using a simple perturbative approach we\nshow that for thick smectic films on a sphere with planar anchoring this\nsolution breaks down, distorting the smectic layers. The instability happens\nwhen the bend elastic constant exceeds the anchoring strength times the radius\nof the inner sphere. Above this threshold, the formation of a periodic\nchevron-like structure, observed experimentally as well, relieves geometric\nfrustration. We quantify the effect of thickness and curvature of smectic\nshells and provide insight into the wavelength of the observed texture.",
        "positive": "Acetone as a Polar Cosolvent for Pyridinium-Based Ionic Liquids: The work reports transport and structure properties of the three\npyridinium-based ionic liquids (RTILs) - N-butylpyridinium hexafluorophosphate\n[BPY][PF6], N-butylpyridinium trifluorosulfonate [BPY][TF] and\nN-butylpyridinium bis(trifluoromethanesulfonyl)imide [BPY][TFSI] - in their\nmixtures with acetone (ACET). The ionic conductivity maximum occurs at 10 mol%\nRTIL, irrespective of the anion. The absolute ionic conductivity value of\n[BPY][TF] is higher than those of other RTILs. This is explained by a weaker\ncation-anion binding than that in [BPY][PF6] and smaller anion size than that\nof [BPY][TFSI]. All the investigated RTILs are infinitely miscible with ACET,\nwhich boosts their diffusivity and conductivity. A small viscosity of ACET\nfavors a drastic viscosity decay in the RTIL-ACET mixtures. Structure analysis\n(radial distribution functions, ionic clusters) of the mixtures are in line\nwith their transport properties providing a reliable microscopic interpretation\nof the observed macroscopic properties. As a molecular co-solvent, ACET\nconstitutes an interesting alternative and competitor to more intensively\ninvestigated liquids."
    },
    {
        "anchor": "Adsorption-Induced Deformation of a Nanoporous Material: Influence of\n  the Fluid-Adsorbent Interaction and Surface Freezing on the Pore-Load Modulus\n  Measurement: Liquid adsorption in nanoporous materials induces their deformation due to\nstrong capillary forces. The linear relationship between the liquid pressure\nand the solid strain (pore-load modulus) provides an experimental technique to\ndetermine the mechanical properties of nanosized solids. Puzzling experimental\nresults have often been reported, leading to a severe reconsideration of the\nmechanical properties of the thin walls, the introduction of surface stresses,\nand the suggestion of a mutual influence of fluid adsorption and matrix\ndeformation. This work presents a molecular simulation examination of the\nfundamentals of the pore-load measurement technique. The pore-load protocol is\nreproduced as in experiments by measuring the solid deformation in presence of\nthe liquid (\"numerical experiment\"), and the result is compared to the expected\nmechanical response of the solid. Focusing on a single nanoplatelet mimicking\nsilicon stiffness, we show that the pore-load protocol is valid as long as the\nliquid in the pores remains liquid. However, when an ordered layer can form at\nthe solid surface, it significantly affects the pore-load measurement. It is\nshown that this may happen above the freezing point even for moderately strong\nfluid-solid interactions. This observation could help for the interpretation of\nexperimental data, in particular in porous silicon, where the expected presence\nof atomically smooth surfaces could favor the formation of highly ordered fluid\nlayers.",
        "positive": "Helical Ribbons as Isometric Textures: Deformations that conserve the parallelism and the distances --between\nlayers, in smectic phases; between columns, in columnar phases-- are\ncommonplace in liquid crystals. The resulting deformed textures have the same\nmass density as in the ground state (an expected property in a liquid) and are\nat the same time isogonic and isometric, which imposes specific geometric\nfeatures. The corresponding order parameter singularities extend over rather\nlarge, macroscopic, distances, e.g., cofocal conics in smectics. This\nwell-known picture is modified when, superimposed to the 1D or 2D\nperiodicities, the structure is helical. Isogony is no longer the rule, but\nisometry (and mass density) can be preserved. This paper discusses the case of\na medium whose structure is made of 1D modulated layers (a lamello-columnar\nphase), assuming that the modulations rotate helically from one layer to the\nnext. The price to pay is that any isometric texture is necessarily frustrated;\nit consists of layers folded into a set of parallel helicoids, in the manner of\na screw dislocation (of macroscopic Burgers vector), the modulations being\nalong the helices, i.e. double-twisted. The singularity set is made of two\nhelical disclination lines. We complete this geometric analysis by a crude\ncalculation of the energy of a helical ribbon. It is suggested that the helical\nribbons observed in the B7 phase of banana-like molecules are such isometric\ntextures. As a side result, let us mention that the description of\ndouble-twist, traditionally made in terms of a partition of the director field\ninto nested cylinders, could more than often be profitably tested against a\npartition into nested helicoids."
    },
    {
        "anchor": "Non-equilibrium effects of micelle formation as studied by a minimum\n  particle-based model: The formation of self assembled structures such as micelles has been\nintensively studied and is well understood. The ability of a solution of\namphiphilic molecules to develop micelles is depending on the concentration and\ncharacterized by the critical micelle concentration (cmc), above which micelle\nformation does occur. Recent studies use a lattice approach in order to\ndetermine cmc and show that the correct modelling and analysis of cluster\nformations is highly non-trivial. We developed a minimalistic coarse grained\nmodel for amphiphilic molecules in the continuum and simulated the time\nevolution via dynamic Monte Carlo simulations in the canonical (NVT) ensemble.\nStarting from a homogeneous system we observed and characterized how the\ninitial fluctuations, yielding small aggregates of amphiphilic molecules, end\nup in the growth of complete micelles. Our model is sufficiently versatile to\naccount for different structures of surfactant systems such as membranes,\nmicelles of variable radius and tubes at high particle densities by adjusting\nparticle density and potential properties. Particle densities and micellization\nrates are investigated and an order parameter is introduced, so that the\ndependence of the micellization process on temperature and surfactant density\ncan be studied. The constant density of free particles for concentrations above\ncmc, e. g. as expected from theoretical considerations, can be reproduced when\nchoosing a careful definition of free volumes. In the cmc regime at low\ntemperatures different non-equilibrium effects are reported, occurring even for\nvery long time-scales.",
        "positive": "Relaxation of curvature induced elastic stress by the\n  Asaro-Tiller-Grinfeld instability: A two-dimensional crystal on the surface of a sphere experiences elastic\nstress due to the incompatibility of the crystal axes and the curvature. A\ncommon mechanism to relax elastic stress is the Asaro-Tiller-Grinfeld (ATG)\ninstability. With a combined numerical and analytical approach we demonstrate,\nthat also curvature induced stress in surface crystals can be relaxed by the\nlong wave length ATG instability. The numerical results are obtained using a\nsurface phase-field crystal (PFC) model, from which we determine the\ncharacteristic wave numbers of the ATG instability for various surface\ncoverages corresponding to different curvature induced compressions. The\nresults are compared with an analytic expression for the characteristic wave\nnumber, obtained from a continuum approach which accounts for hexagonal\ncrystals and intrinsic PFC symmetries. We find our numerical results in\naccordance with the analytical predictions."
    },
    {
        "anchor": "Correlation function of random heteropolymer solutions: We study the density-density correlation function of the dense random\nheteropolymer solutions. We show that a phase transition is possible due to the\nheterogeneity of polymers. We also show that the critical behavior of the\nsystem is described by the O(N) model at N=0.",
        "positive": "Coupling between particle shape and long-range interaction in the\n  high-density regime: By using long-range interacting polygons, we experimentally probe the\ncoupling between particle shape and long-range interaction. For two typical\nspace-filling polygons, square and triangle, we find two types of coupling\nmodes that predominantly control the structure formation. Specifically, the\nrotational ordering of squares brings a lattice deformation that produces a\nhexagonal-to-rhombic transition in the high-density regime, whereas the\nalignment of triangles introduces a large geometric frustration that causes an\norder-to-disorder transition. Moreover, the two coupling modes lead to small\nand large \"internal roughness\" of the two systems, and thus predominantly\ncontrol their structure relaxations. Our study thus provides a physical picture\nto the coupling between long-range interaction effect and short-range shape\neffect in the high-density regime unexplored before."
    },
    {
        "anchor": "Short pyridine-furan springs exhibit bistable dynamics of Duffing\n  oscillators: The intensive development of nanodevices acting as two-state systems has\nmotivated the search for nanoscale molecular structures whose dynamics are\nsimilar to those of bistable mechanical systems, such as Euler arches and\nDuffing oscillators. Of particular interest are the molecular structures\ncapable of spontaneous vibrations and stochastic resonance. Recently,\noligomeric molecules that were a few nanometers in size and exhibited the\nbistable dynamics of an Euler arch were identified through molecular dynamics\nsimulations of short fragments of thermo-responsive polymers subject to force\nloading. In this article, we present molecular dynamics simulations of short\npyridine-furan springs a few nanometers in size and demonstrated the bistable\ndynamics of a Duffing oscillator with thermally-activated spontaneous\nvibrations and stochastic resonance.",
        "positive": "Soluble Hydrogen-bonding Interpolymer Complexes in Water: A Small-Angle\n  Neutron Scattering Study: The hydrogen-bonding interpolymer complexation between poly(acrylic acid)\n(PAA) and the poly(N,N-dimethylacrylamide) (PDMAM) side chains of the\nnegatively charged graft copolymer poly(acrylic\nacid-co-2-acrylamido-2-methyl-1-propane sulfonic acid)-graft-poly(N, N\ndimethylacrylamide) (P(AA-co-AMPSA)-g-PDMAM), containing 48 wt % of PDMAM, and\nshortly designated as G48, has been studied by small-angle neutron scattering\nin aqueous solution. Complexation occurs at low pH (pH < 3.75), resulting in\nthe formation of negatively charged colloidal particles, consisting of\nPAA/PDMAM hydrogen-bonding interpolymer complexes, whose radius is estimated to\nbe around 165 A. As these particles involve more than five graft copolymer\nchains, they act as stickers between the anionic chains of the graft copolymer\nbackbone. This can explain the characteristic thickening observed in past\nrheological measurements with these mixtures in the semidilute solution, with\ndecreasing pH. We have also examined the influence of pH and PAA molecular\nweight on the formation of these nanoparticles."
    },
    {
        "anchor": "Nanoparticle ordering in sandwiched polymer brushes: The organization of nano-particles inside grafted polymer layers is governed\nby the interplay of polymer-induced entropic interactions and the action of\nexternally applied fields. Earlier work had shown that strong external forces\ncan drive the formation of colloidal structures in polymer brushes. Here we\nshow that external fields are not essential to obtain such colloidal patterns:\nwe report Monte Carlo and Molecular dynamics simulations that demonstrate that\nordered structures can be achieved by compressing a `sandwich' of two grafted\npolymer layers, or by squeezing a coated nanotube, with nano-particles in\nbetween. We show that the pattern formation can be efficiently controlled by\nthe applied pressure, while the characteristic length--scale, i.e. the typical\nwidth of the patterns, is sensitive to the length of the polymers. Based on the\nresults of the simulations, we derive an approximate equation of state for\nnano-sandwiches.",
        "positive": "Statistical Properties of a 2D Granular Material Subjected to Cyclic\n  Shear: This work focuses on the evolution of structure and stress for an\nexperimental system of 2D photoelastic particles that is subjected to multiple\ncycles of pure shear. Throughout this process, we determine the contact network\nand the contact forces using particle tracking and photoelastic techniques.\nThese data yield the fabric and stress tensors and the distributions of contact\nforces in the normal and tangential directions. We then find that there is, to\na reasonable approximation, a functional relation between the system pressure,\n$P$, and the mean contact number, $Z$. This relationship applies to the shear\nstress $\\tau$, except for the strains in the immediate vicinity of the contact\nnetwork reversal. By contrast, quantities such as $P$, $\\tau$ and $Z$ are\nstrongly hysteretic functions of the strain, $\\epsilon$. We find that the\ndistributions of normal and tangential forces, when expressed in terms of the\nappropriate means, are essentially independent of strain. We close by analyzing\na subset of shear data in terms of strong and weak force networks."
    },
    {
        "anchor": "Long-range Casimir interactions between impurities in nematic liquid\n  crystals and the collapse of polymer chains in such solvents: The elastic interactions between objects embedded in a nematic liquid crystal\nare usually caused by the average distorsion-rather than by the fluctuations-of\nthe nematic orientational field. We argue that for sufficiently small\nparticles, the nematic-mediated interaction originates purely from the\nfluctuations of the nematic director. This Casimir interaction decays as\nd^(-6), d being the distance between the particles, and it dominates van der\nWaals interactions close to the isotropic-to-nematic transition. Considering\nthe nematic as a polymer solvent, we show that the onset of this Casimir\ninteraction at the isotropic-to-nematic transition can discontinuously induce\nthe collapse of a flexible polymer chain from the swollen state to the globular\nstate, without crossing the Theta-point.",
        "positive": "Quantum Monte Carlo calculations of van der Waals interactions between\n  aromatic benzene rings: The magnitude of finite-size effects and Coulomb interactions in quantum\nMonte Carlo simulations of van der Waals interactions between weakly bonded\nbenzene molecules are investigated. To that extent, two trial wave functions of\nthe Slater-Jastrow and Backflow-Slater-Jastrow types are employed to calculate\nthe energy-volume equation of state. We assess the impact of the backflow\ncoordinate transformation on the non-local correlation energy.\n  We found that the effect of finite-size errors in quantum Monte Carlo\ncalculations on energy differences is particularly large and may even be more\nimportant than the employed trial wave function. Beside the cohesive energy,\nthe singlet excitonic energy gap and the energy gap renormalization of\ncrystalline benzene at different densities are computed."
    },
    {
        "anchor": "Statics and Dynamics of the Wormlike Bundle Model: Bundles of filamentous polymers are primary structural components of a broad\nrange of cytoskeletal structures, and their mechanical properties play key\nroles in cellular functions ranging from locomotion to mechanotransduction and\nfertilization. We give a detailed derivation of a wormlike bundle model as a\ngeneric description for the statics and dynamics of polymer bundles consisting\nof semiflexible polymers interconnected by crosslinking agents. The elastic\ndegrees of freedom include bending as well as twist deformations of the\nfilaments and shear deformation of the crosslinks. We show that a competition\nbetween the elastic properties of the filaments and those of the crosslinks\nleads to renormalized effective bend and twist rigidities that become\nmode-number dependent. The strength and character of this dependence is found\nto vary with bundle architecture, such as the arrangement of filaments in the\ncross section and pretwist. We discuss two paradigmatic cases of bundle\narchitecture, a uniform arrangement of filaments as found in F-actin bundles\nand a shell-like architecture as characteristic for microtubules. Each\narchitecture is found to have its own universal ratio of maximal to minimal\nbending rigidity, independent of the specific type of crosslink induced\nfilament coupling; our predictions are in reasonable agreement with available\nexperimental data for microtubules. Moreover, we analyze the predictions of the\nwormlike bundle model for experimental observables such as the tangent-tangent\ncorrelation function and dynamic response and correlation functions. Finally,\nwe analyze the effect of pretwist (helicity) on the mechanical properties of\nbundles. We predict that microtubules with different number of protofilaments\nshould have distinct variations in their effective bending rigidity.",
        "positive": "Stripes polymorphism and water-like anomaly in hard core-soft corona\n  dumbbells: In this paper we investigate the phase diagram of a dumbbell model composed\nof two hard-core soft-corona beads through $NpT$ simulations. This particular\nsystem was chosen due to its ability to exhibit a diverse range of stripe\npatterns. Analyzing the thermodynamic and structural changes along compression\nisotherms, we explore the transition between these distinct patterns. In\naddition to the stripe and Low-Density-Triangular solid phases obtained, we\nobserved a Nematic Anisotropic phase characterized by a polymer-like pattern at\nhigh temperatures and intermediate pressures. Furthermore, we demonstrate the\nsignificant role played by the new characteristic length scale, which arises\nfrom the anisotropic geometry of the dumbbell structure, in the transition\nbetween the stripes patterns. Notably, not only do the structural properties\nexhibit intriguing behavior, but the diffusion and density in the nematic fluid\nphase also displays a water-like anomalous increase under compression. Those\nfindings can be valuable in guiding the design of materials based on\nnanoparticles, with the aim of achieving specific mesopatterns."
    },
    {
        "anchor": "Model of nanocrystal formation in solution by burst nucleation and\n  diffusional growth: The phenomenon of burst nucleation in solution, in which a period of apparent\nchemical inactivity is followed by a sudden and explosive growth of nucleated\nparticles from a solute species, has been given a widely accepted qualitative\nexplanation by LaMer and co-workers. Here, we present a model with the\nassumptions of instantaneous thermalization below the critical nucleus size and\nirreversible diffusive growth above the critical size, which for the first time\nformulates LaMer's explanation of burst nucleation in a manner allowing\nquantitative calculations. The behavior of the model at large times is derived,\nwith the result that the average cluster size, as measured by the number of\natoms, grows linearly with time, while the width of the cluster distribution\ngrows as the square root of time. We develop an effective numerical scheme to\nintegrate the equations of the model and compare the asymptotic expressions to\nresults from numerical simulation. Finally, we discuss the physical effects\nwhich cause real nucleation processes in solution to deviate from the behavior\nof the model.",
        "positive": "Role of temperature and alignment activity on kinetics of coil-globule\n  transition of a flexible polymer: We study the nonequilibrium kinetics during the coil-globule transition of a\nflexible polymer chain with active beads after a quench from good to poor\nsolvent condition using molecular dynamics simulation. Activity for each bead\nis introduced via the well-known Vicsek-like alignment rule due to which the\nvelocity of a bead tries to align towards the average direction of its\nneighbors. We investigate the role of quenching temperature with varying\nactivity during collapse of this polymer. We find that although for lower\nactivities the kinetics remains qualitatively similar for different\ntemperatures, for higher activity noticeable differences can be identified."
    },
    {
        "anchor": "Influence of silicon nanocone on cell membrane self-sealing capabilities\n  for targeted drug delivery -- computer simulation study: Efficient and non-invasive techniques of cargo delivery to biological cells\nare the focus of biomedical research because of their great potential\nimportance for targeted drug therapy. Therefore, much effort is being made to\nstudy the characteristics of using nano-based biocompatible materials as\nsystems that can facilitate this task while ensuring appropriate self-sealing\nof the cell membrane. Here, we study the effects of indentation and withdrawal\nof nanospear on phospholipid membrane by applying steered molecular dynamics\n(SMD) technique. Our results show that the withdrawal process directly depends\non the initial position of the nanocone. The average force and work are\nconsiderably more significant in case of the withdrawal starting from a larger\ndepth. This result is attributed to stronger hydrophobic interactions between\nthe nanocone and lipid tails of the membrane molecules. Furthermore, when the\nindenter was started from the lower initial depth, the number of lipids removed\nfrom the membrane was several times smaller than the deeper indentation. The\nchoice of the least invasive method for nanostructure-assisted drug delivery is\ncrucial for possible applications in medicine. Therefore, the results presented\nin this work might be helpful in efficient and safe drug delivery with\nnanomaterials.",
        "positive": "Emulsification in binary liquids containing colloidal particles: a\n  structure-factor analysis: We present a quantitative confocal-microscopy study of the transient and\nfinal microstructure of particle-stabilised emulsions formed via demixing in a\nbinary liquid. To this end, we have developed an image-analysis method that\nrelies on structure factors obtained from discrete Fourier transforms of\nindividual frames in confocal image sequences. Radially averaging the squared\nmodulus of these Fourier transforms before peak fitting allows extraction of\ndominant length scales over the entire temperature range of the quench. Our\nprocedure even yields information just after droplet nucleation, when the\n(fluorescence) contrast between the two separating phases is scarcely\ndiscernable in the images. We find that our emulsions are stabilised on\nexperimental time scales by interfacial particles and that they are likely to\nhave bimodal droplet-size distributions. We attribute the latter to coalescence\ntogether with creaming being the main coarsening mechanism during the late\nstages of emulsification and we support this claim with (direct)\nconfocal-microscopy observations. In addition, our results imply that the\nobserved droplets emerge from particle-promoted nucleation, possibly followed\nby a free-growth regime. Finally, we argue that creaming strongly affects\ndroplet growth during the early stages of emulsification. Future investigations\ncould clarify the link between quench conditions and resulting microstructure,\npaving the way for tailor-made particle-stabilised emulsions from binary\nliquids."
    },
    {
        "anchor": "Overcomplete free energy functional for D=1 particle systems with next\n  neighbor interactions: We deduce an overcomplete free energy functional for D=1 particle systems\nwith next neighbor interactions, where the set of redundant variables are the\nlocal block densities $\\varrho_i$ of $i$ interacting particles. The idea is to\nanalyze the decomposition of a given pure system into blocks of $i$ interacting\nparticles by means of a mapping onto a hard rod mixture. This mapping uses the\nlocal activity of component $i$ of the mixture to control the local association\nof $i$ particles of the pure system. Thus it identifies the local particle\ndensity of component $i$ of the mixture with the local block density\n$\\varrho_i$ of the given system. Consequently, our overcomplete free energy\nfunctional takes on the hard rod mixture form with the set of block densities\n$\\varrho_i$ representing the sequence of partition functions of the local\naggregates of particle numbers $i$. The system of equations for the local\nparticle density $\\varrho$ of the original system is closed via a subsidiary\ncondition for the block densities in terms of $\\varrho$. Analoguous to the\nuniform isothermal-isobaric technique, all our results are expressible in terms\nof effective pressures. We illustrate the theory with two standard examples,\nthe adhesive interaction and the square-well potential. For the uniform case,\nour proof of such an overcomplete format is based on the exponential\nboundedness of the number of partitions of a positive integer (Hardy-Ramanujan\nformula) and on Varadhan's theorem on the asymptotics of a class of integrals.\nWe also discuss the applicability of our strategy in higher dimensional space,\nas well as models suggested thereof.",
        "positive": "Methodical Fitting for Mathematical Models of Rubber-like Materials: A great variety of models can describe the non-linear response of rubber to\nuni-axial tension. Yet an in-depth understanding of the successive stages of\nlarge extension is still lacking. We show that the response can be broken down\nin three steps, which we delineate by relying on a simple formatting of the\ndata, the so-called Mooney transform. First, the small-to-moderate regime,\nwhere the polymeric chains unfold easily and the Mooney plot is almost linear.\nSecond, the strain-hardening regime, where blobs of bundled chains unfold to\nstiffen the response in correspondence to the \"upturn\" of the Mooney plot.\nThird, the limiting-chain regime, with a sharp stiffening occurring as the\nchains extend towards their limit. We provide strain-energy functions with\nterms accounting for each stage, that (i) give an accurate local and then\nglobal fitting of the data; (ii) are consistent with weak non-linear elasticity\ntheory; and (iii) can be interpreted in the framework of statistical mechanics.\nWe apply our method to Treloar's classical experimental data and also to some\nmore recent data. Our method not only provides models that describe the\nexperimental data with a very low quantitative relative error, but also shows\nthat the theory of non-linear elasticity is much more robust that seemed at\nfirst sight."
    },
    {
        "anchor": "Effect of thermal noise on vesicles and capsules in shear flow: We add thermal noise consistently to reduced models of undeformable vesicles\nand capsules in shear flow and derive analytically the corresponding stochastic\nequations of motion. We calculate the steady-state probability distribution\nfunction and construct the corresponding phase diagrams for the different\ndynamical regimes. For fluid vesicles, we predict that at small shear rates\nthermal fluctuations induce a tumbling motion for any viscosity contrast. For\nelastic capsules, due to thermal mixing, an intermittent regime appears in\nregions where deterministic models predict only pure tank treading or tumbling.",
        "positive": "Universality of Ultrasonic attenuation in amorphous systems at low\n  temperatures: The competition between unretarded dispersion interactions between molecules\nprevailing at medium range order length scales and their phonon induced\ncoupling at larger scales leads to appearance of nano-scale sub structures in\namorphous systems. The complexity of intermolecular interactions gives rise to\nrandomization of their operators. Based on a random matrix modelling of the\nHamiltonian and its linear response to an external strain field, we show that\nthe ultrasonic attenuation coefficient can be expressed as a ratio of two\ncrucial length-scales related to molecular dynamics. A constant value of the\nratio for a wide range of materials then provides a theoretical explanation of\nthe experimentally observed universality of the ultrasonic attenuation\ncoefficient at low temperatures."
    },
    {
        "anchor": "Crystallization in a dense suspension of self-propelled particles: Using Brownian dynamics computer simulations we show that a two-dimensional\nsuspension of self-propelled (\"active\") colloidal particles crystallizes at\nsufficiently high densities. Compared to the equilibrium freezing of passive\nparticles the freezing density is both significantly shifted and depends on the\nstructural or dynamical criterion employed. In non-equilibrium the transition\nis accompanied by pronounced structural heterogeneities. This leads to a\ntransition region between liquid and solid in which the suspension is globally\nordered but unordered liquid-like \"bubbles\" still persist.",
        "positive": "Low energy modes and Debye behavior in a colloidal crystal: withdrawn by the author due to double submission in arXiv:1102.4271 ."
    },
    {
        "anchor": "Impact of Asymmetries in Valences and Diffusivities on the Transport of\n  a Binary Electrolyte in a Charged Cylindrical Pore: Ion transport in porous media is present in a wealth of technologies, e.g.,\nenergy storage devices such as batteries and supercapacitors, and environmental\ntechnologies such as electrochemical carbon capture and capacitive\ndeionization. Recent studies on flat-plate electrodes have demonstrated that\nasymmetries in ion properties, such as valences and diffusivities, lead to\nintriguing and counter-intuitive physical phenomena. Yet, the consequences of\nsuch asymmetries to ion transport have seldom been explored in porous\ngeometries. To bridge this knowledge gap, we conduct a perturbation expansion\nof the Poisson-Nernst-Planck equations in a cylindrical pore in the limit of\nsmall potentials for a binary electrolyte with arbitrary valences and\ndiffusivities. We obtain good agreement between the perturbation analysis and\ndirect numerical simulations. Our analysis reveals that the charge and the salt\ntransport are coupled with each other. Further, the coupling between the charge\nand salt transport processes is enhanced with an increase in valence and\ndiffusivity asymmetries of ions. We observe that the mismatch of the ionic\ndiffusivities induces a non-trivial salt dynamics, producing either transient\ndepletion or enhancement of salt in the pore. In the regime of high static\ndiffusion layer conductance, we obtain an analytical solution to our\nperturbation model. The solution elucidates how electrolyte asymmetry induces\ntwo charging timescales that are set by the relative pore size. In the\noverlapping-double-layer regime, these timescales reduce to the diffusion times\nof each ion such that the transport of the two ions appears to be decoupled.\nOverall, our work underscores that the asymmetry in cation and anion\ndiffusivities fundamentally alters the behavior of ionic transport inside a\ncharged cylindrical pore and opens up new avenues of research on electrolyte\ntransport in porous materials.",
        "positive": "Creep and fluidity of a real granular packing near jamming: We study the internal dynamical processes taking place in a granular packing\nbelow yield stress. At all packing fractions and down to vanishingly low\napplied shear, a logarithmic creep is evidenced. The experiments are analyzed\nunder the scope of a visco-elastic model introducing an internal \"fluidity\"\nvariable. For all experiments, the creep dynamics can be rescaled onto a unique\ncurve which displays jamming at the random-close-packing limit. At each packing\nfraction, a stress value is evidenced, corresponding to the onset of internal\ngranular reorganisation leading to a slowing down the creep dynamics before the\nfinal yield."
    },
    {
        "anchor": "Diffusion of self-propelled Janus tracer in polymeric environment: Artificially synthesized Janus particles have tremendous prospective as\nin-vivo drug-delivery agents due to the possibility of self-propulsion by\nexternal stimuli. Here we report the first ever computational study of\ntranslational and rotational motion of self-propelled Janus tracers in a het-\nerogeneous polymeric environment. The presence of polymers makes the\ntranslational mean square displacement (MSD) of the Janus tracer to grow very\nslowly as compared to that of a free Janus tracer, but surprisingly the mean\nsquare angular displacement (MSAD) is significantly increased as observed in a\nrecent experiment. Moreover, with the increasing propulsion velocity, MSAD\ngrows even faster. However, when the repulsive polymers are replaced with\npolymers with sticky zones, MSD and MSAD both show sharp decline.",
        "positive": "Nonlinear Elasticity in Biological Gels: Unlike most synthetic materials, biological materials often stiffen as they\nare deformed. This nonlinear elastic response, critical for the physiological\nfunction of some tissues, has been documented since at least the 19th century,\nbut the molecular structure and the design principles responsible for it are\nunknown. Current models for this response require geometrically complex ordered\nstructures unique to each material. In this Article we show that a much simpler\nmolecular theory accounts for strain stiffening in a wide range of molecularly\ndistinct biopolymer gels formed from purified cytoskeletal and extracellular\nproteins. This theory shows that systems of semi-flexible chains such as\nfilamentous proteins arranged in an open crosslinked meshwork invariably\nstiffen at low strains without the need for a specific architecture or multiple\nelements with different intrinsic stiffnesses."
    },
    {
        "anchor": "Weak disorder: anomalous transport and diffusion are normal yet again: Particles driven through a periodic potential by an external constant force\nare known to exhibit a pronounced peak of the diffusion around a critical force\nthat defines the transition between locked and running states. It has recently\nbeen shown both experimentally and numerically that this peak is greatly\nenhanced if some amount of spatial disorder is superimposed on the periodic\npotential. Here we show that beyond a simple enhancement lies a much more\ninteresting phenomenology. For some parameter regimes the system exhibits a\nrich variety of behaviors from normal diffusion to superdiffusion, subdiffusion\nand even subtransport.",
        "positive": "Finite-size study of the athermal quasistatic yielding transition in\n  structural glasses: We present a finite-size study of the athermal quasistatic yielding\ntransition in structural glasses featuring a wide range of mechanical disorder.\nWe find a crossover from gradual yielding in small systems, to a macroscopic\ndiscontinuous stress drop as the system size is increased. The crossover size\ngrows significantly as the sample's structural disorder approaches the maximal\nvalue that a glass can attain. Our results suggest an analogy between the\nnature of the athermal quasistatic yielding transition in structural glasses\nand brittle fracture of fuse models and elastic networks. We discuss our\nresults in the context of recent claims in the literature."
    },
    {
        "anchor": "Volume terms for charged colloids: a grand-canonical treatment: We present a study of thermodynamic properties of suspensions of charged\ncolloids on the basis of linear Poisson-Boltzmann theory. We calculate the\neffective Hamiltonian of the colloids by integrating out the ionic degrees of\nfreedom grand-canonically. This procedure not only yields the well-known\npairwise screened-Coulomb interaction between the colloids, but also additional\nvolume terms which affect the phase behavior and the thermodynamic properties\nsuch as the osmotic pressure. These calculations are greatly facilitated by the\ngrand-canonical character of our treatment of the ions, and allow for\nrelatively fast computations compared to earlier studies in the canonical\nensemble. Moreover, the present derivation of the volume terms are relatively\nsimple, make a direct connection with Donnan equilibrium, yield an explicit\nexpression for the effective screening constant, and allow for extensions to\ninclude, for instance, nonlinear effects.",
        "positive": "An Alternative Method to Deduce Bubble Dynamics in Single Bubble\n  Sonoluminescence Experiments: In this paper we present an experimental approach that allows to deduce the\nimportant dynamical parameters of single sonoluminescing bubbles (pressure\namplitude, ambient radius, radius-time curve) The technique is based on a few\npreviously confirmed theoretical assumptions and requires the knowledge of\nquantities such as the amplitude of the electric excitation and the phase of\nthe flashes in the acoustic period. These quantities are easily measurable by a\ndigital oscilloscope, avoiding the cost of expensive lasers, or ultrafast\ncameras of previous methods. We show the technique on a particular example and\ncompare the results with conventional Mie scattering. We find that within the\nexperimental uncertainties these two techniques provide similar results."
    },
    {
        "anchor": "Birth and Death of One-dimensional Domains in Cylindrically Confined\n  Liquid Crystals: Nematic liquid crystal (LC) is a partially ordered matter that has been a\npopular model system for studying a variety of topological behaviors in\ncondensed matter. In this work, utilizing a spontaneously twisting achiral LC,\nwe introduce a one-dimensional (1D) model system to investigate how domains and\ntopological defects arise and annihilate, reminiscing the Kibble-Zurek\nmechanism. Because of the unusual elastic properties, lyotropic chromonic LCs\nform a double-twist structure in a cylindrical capillary with degenerate planar\nanchoring, exhibiting chiral symmetry breaking despite the absence of intrinsic\nchirality. Consequently, the domains of different handedness coexist with equal\nprobabilities, forming the topological defects between them. We experimentally\nmeasure the domain-length distribution and its time evolution, best fitted by a\nthree-parameter log-normal distribution. We propose that the coalescence within\na train of 1D domains having the normal length distribution and randomly\nassigned handedness, may lead to the domains of the log-normal-like length\ndistribution. Our cylindrically confined LC provides a practical model system\nto study the formation and annihilation of domains and defects in 1D.",
        "positive": "Friction and the oscillatory motion of granular flows: This contribution reports on numerical simulations of 2D granular flows on\nerodible beds. The broad aim is to investigate whether simple flows of model\ngranular matter exhibits spontaneous oscillatory motion in generic flow\nconditions, and in this case, whether the frictional properties of the contacts\nbetween grains may affect the existence or the characteristics of this\noscillatory motion. The analysis of different series of simulations show that\nthe flow develops an oscillatory motion with a well-defined frequency which\nincreases like the inverse of the velocity's square root. We show that the\noscillation is essentially a surface phenomena. The amplitude of the\noscillation is higher for lower volume fractions, and can thus be related to\nthe flow velocity and grains friction properties. The study of the influence of\nthe periodic geometry of the simulation cell shows no significant effect. These\nresults are discussed in relation to sonic sands."
    },
    {
        "anchor": "Programming Soft Robots with Flexible Mechanical Metamaterials: The complex behavior of highly deformable mechanical metamaterials can\nsubstantially enhance the performance of soft robots.",
        "positive": "Theory of superlocalized magnetic nanoparticle hyperthermia: rotating\n  versus oscillating fields: The main idea of magnetic hyperthermia is to increase locally the temperature\nof the human body by means of injected superparamagnetic nanoparticles. They\nabsorb energy from a time-dependent external magnetic field and transfer it\ninto their environment. In the so-called superlocalization, the combination of\nan applied oscillating and a static magnetic field gradient provides even more\nfocused heating since for large enough static field the dissipation is\nconsiderably reduced. Similar effect was found in the deterministic study of\nthe rotating field combined with a static field gradient. Here we study\ntheoretically the influence of thermal effects on superlocalization and on\nheating efficiency. We demonstrate that when time-dependent steady state\nmotions of the magnetisation vector are present in the zero temperature limit,\nthen deterministic and stochastic results are very similar to each other. We\nalso show that when steady state motions are absent, the superlocalization is\nseverely reduced by thermal effects. Our most important finding is that in the\nlow frequency range ($\\omega \\to 0$) suitable for hyperthermia, the oscillating\napplied field is shown to result in two times larger intrinsic loss power and\nspecific absorption rate then the rotating one with identical superlocalization\nability which has importance in technical realisation."
    },
    {
        "anchor": "Wetting and cavitation pathways on nanodecorated surfaces: In this contribution we study wetting and nucleation of vapor bubbles on\nnanodecorated surfaces via free energy molecular dynamics simulations. The\nresults shed light on the stability of superhydrophobicity in submerged\nsurfaces with nanoscale corrugations. The re-entrant geometry of the cavities\nunder investigation is capable of sustaining a confined vapor phase within the\nsurface roughness (Cassie state) both for hydrophobic and hydrophilic\ncombinations of liquid and solid. The atomistic system is of nanometric size;\non this scale thermally activated events can play an important role ultimately\ndetermining the lifetime of the Cassie state. Such superhydrophobic state can\nbreak down by full wetting of the texture at large pressures (Cassie-Wenzel\ntransition) or by nucleating a vapor bubble at negative pressures (cavitation).\nSpecialized rare event techniques show that several pathways for wetting and\ncavitation are possible, due to the complex surface geometry. The related free\nenergy barriers are of the order of 100 k_B T and vary with pressure. The\natomistic results are found to be in semi-quantitative accord with macroscopic\ncapillarity theory. However, the latter is not capable of capturing the density\nfluctuations, which determine the destabilization of the confined liquid phase\nat negative pressures (liquid spinodal).",
        "positive": "Fluid-solid transition in unsteady, homogeneous, granular shear flows: Discrete element numerical simulations of unsteady, homogeneous shear flows\nhave been performed by instantly applying a constant shear rate to a random,\nstatic, isotropic assembly of identical, soft, frictional spheres at either\nzero or finite pressure by keeping constant the solid volume fraction until the\nsteady state is reached. If the system is slowly sheared, or, equivalently, if\nthe particles are sufficiently rigid, the granular material exhibits either\nlarge or small fluctuations in the evolving pressure, depending whether the\naverage number of contacts per particle (coordination number) is less or larger\nthan a critical value. The amplitude of the pressure fluctuations is\nrate-dependent when the coordination number is less than the critical and\nrate-independent otherwise, signatures of fluid-like and solid-like behaviour,\nrespectively. The same critical coordination number has been previously found\nto represent the minimum value at which rate-independent components of the\nstresses develop in steady, simple shearing and the jamming transition in\nisotropic random packings. The observed complex behaviour of the measured\npressure in the fluid-solid transition clearly suggests the need for\nincorporating in a nontrivial way the coordination number, the solid volume\nfraction, the particle stiffness and the intensity of the particle agitation in\nconstitutive models for the onset and the arrest of granular flows."
    },
    {
        "anchor": "Segregation and Stability of Binary Granular Mixtures: We measure stability of two-dimensional granular mixtures in a rotating drum\nand relate grain configurations to stability. For our system, the smaller but\nsmoother grains cluster near the center of the drum, while the larger, rougher\ngrains remain near the outer edge. One consequence of the size segregation is\nthat the smaller grains heavily influence the stability of the heap. We find\nthat the maximum angle of stability is a non-linear function of composition,\nchanging particularly rapidly when small grains are first added to a\nhomogeneous pile of large grains. We conclude that the grain configuration\nwithin the central portion of the heap plays a prominent role in stability.",
        "positive": "The effect of configurational complexity in heteropolymers on the\n  coil-globule phase-transition: The coil-globule transition of hetero-polymer chains is studied here. By\nmeans of extensive Molecular Dynamics simulations, we show that the transition\nis directly linked to the complexity of the chain, which depends on the number\nof chemical species defined in the environment and the location of the binding\nsites along the polymer. In addition, when the number of species increases, we\nfind that the distribution of binding sites plays an important role in\ntriggering the transition, beyond the standard control parameters of the\npolymer model, i.e. binders concentration and binding affinity. Overall, our\nresults show that by increasing the system complexity new organizational layers\nemerge, thus allowing a more structured control on the polymer thermodynamic\nstate. This can be potentially applied to the study of chromatin architecture,\nas such polymer models have been broadly used to understand the molecular\nmechanisms of genome folding."
    },
    {
        "anchor": "Periodic boundary conditions for the simulation of uniaxial extensional\n  flow: It is very common with molecular dynamics and other simulation techniques to\napply Lees-Edwards periodic boundary conditions (PBCs) for the simulation of\nshear flow. However the behavior of a complex liquid can be quite different\nunder extensional flow. Simple deformation of a simulation cell and its\nperiodic images only allows for simulations of these flows with short duration.\nFor the simulation of planar extensional flow it was recognized that the PBCs\nof Kraynik and Reinelt [Int. J. Multiphase Flow 18, 1045 (1992)] could be used\nto perform simulations of this flow with arbitrary duration. However, a very\ncommon extensional flow in industrial applications and experiment is uniaxial\nextensional flow. Kraynik and Reinelt found that their method could not be\ndirectly generalized to this flow because of the lack of a lattice which\nreproduces itself during uniaxial extension. PBCs are presented in this article\nwhich solve this problem, by finding a lattice which is compatible with the\nflow, finding the reduced basis to the lattice at all times and using this\nbasis when calculating the position and separation of particles. Using these\nnew PBCs we perform nonequilibrium molecular dynamics simulations of a simple\nliquid and show that the technique gives results which agree with those from\nsimulations using simply deforming PBCs.",
        "positive": "Finite-size effects in the diffusion dynamics of a glass-forming binary\n  mixture with large size ratio: Extensive molecular dynamics (MD) computer simulations of an equimolar\nglass-forming AB mixture with large size ratio are presented. While the large A\nparticles show a glass transition around the critical density of mode coupling\ntheory $\\rho_c$, the small B particles remain mobile with a relatively weak\ndecrease of their self diffusion coefficient $D_{\\rm B}$ with increasing\ndensity. Surprisingly, around $\\rho_c$, the self-diffusion coefficient of the A\nparticles, $D_{\\rm A}$, also starts to follow a rather weak dependence on\ndensity. We show that this is due to finite-size effects that can be understood\nfrom the analysis of the collective interdiffusion dynamics."
    },
    {
        "anchor": "Non-Amontons behavior of friction in single contacts: We report on the frictional properties of a single contact between a glassy\npolymer lens and a flat silica substrate covered either by a disordered or by a\nself-assembled alkylsilane monolayer. We find that, in contrast to common\nbelief, the Amontons proportionality between frictional and normal stresses\ndoes not hold. Besides, we observe that the velocity dependence of the sliding\nstress is strongly sensitive to the structure of the silane layer. Analysis of\nthe frictional rheology observed on both disordered and self-assembled\nmonolayers suggests that dissipation is controlled by the plasticity of a\nglass-like interfacial layer in the former case, and by pinning of polymer\nchains on the substrate in the latter one.",
        "positive": "Percolation induced gel-gel phase separation in a dilute polymer network: Cosmic large-scale structures, animal flocks, and living tissues are\nnon-equilibrium organized systems created by dissipative processes. Despite the\nuniqueness, the realization of dissipative structures is still difficult.\nHerein, we report that a network formation process in a dilute system is a\ndissipative process, leading to percolation induced gel-gel phase separation\n(GGPS) in a prominent miscible polymer-water system. The dilute system, which\nforms a monophase structure at the percolation threshold, eventually separates\ninto two gel phases in a longer time scale as the network formation progresses.\nThe dilute hydrogel with GGPS exhibits an unexpected mesoscale co-continuous\nstructure and induces adipose growth in subcutaneous. The formation mechanism\nof GGPS and a cosmic large-scale structure is analogous, in terms of attractive\ninteractions in a diluted system driving phase separation. This unique\nphenomenon unveils the possibility of dissipative structures enabling advanced\nfunctionalities and will stimulate research fields related to dissipative\nstructures."
    },
    {
        "anchor": "Disclination loop behavior near the nematic-isotropic transition: We investigate the behavior of disclination loops in the vicinity of the\nfirst order nematic-isotropic transition in the Lebwohl-Lasher and related\nmodels. We find that two independent measures of the transition temperature,\nthe free energy and the distribution of disclination line segments, give\nessentially identical values. We also calculate the distribution function D(p)\nof disclination loops of perimeter p and fit it to a quasiexponential form.\nBelow the transition, D(p) falls off exponentially, while in the neighborhood\nof the transition it decays with a power law exponent approximately equal to\n2.5, consistent with a \"blowout\" of loops at the transition. In a modified\nLebwohl-Lasher model with a strongly first-order transition we are able to\nmeasure a jump in the disclination line tension at the transition, which is too\nsmall to be measured in the Lebwohl-Lasher model. We also measure the monopole\ncharge of the disclination loops and find that in both the original and\nmodified Lebwohl-Lasher models, there are large loops which carry monopole\ncharge, while smaller isolated loops do not. Overall the nature of the\ntopological defects in both models is very similar.",
        "positive": "Implementation note on a minimal hybrid lubrication/granular dynamics\n  model for dense suspensions: We describe and summarize a class of minimal numerical models emerged from\nrecent development of simulation methods for dense particle suspensions in\noverdamped linear flows. The main ingredients include (i) a frame-invariant,\nshort-range lubrication model for spherical particles, and (ii) a soft-core,\nstick/slide frictional contact model activated when particles overlap. We\nimplement a version of the model using a modified velocity-Verlet algorithm\nthat explicitly solves the $N$-body dynamical system in $\\mathcal{O}(cN)$\noperations, where $c$ is a kernel constant depending on the cutoff of particle\ninteractions. The implementation is validated against literature results on\njamming transition and shear thickening suspensions from 40% to 64% volume\nfractions. Potential strategies to extend the present methodology to\nnon-spherical particles are also suggested for very concentrated suspensions."
    },
    {
        "anchor": "Defect annihilation and proliferation in active nematics: Liquid crystals inevitably possess topological defect excitations generated\nthrough boundary conditions, applied fields or in quenches to the ordered\nphase. In equilibrium pairs of defects coarsen and annihilate as the uniform\nground state is approached. Here we show that defects in active liquid crystals\nexhibit profoundly different behavior, depending on the degree of activity and\nits contractile or extensile character. While contractile systems enhance the\nannihilation dynamics of passive systems, extensile systems act to drive\ndefects apart so that they swarm around in the manner of topologically\nwell-characterized self-propelled particles. We develop a simple analytical\nmodel for the defect dynamics which reproduces the key features of both the\nnumerical solutions and recent experiments on microtuble-kinesin assemblies.",
        "positive": "Effect of particle size distribution on polydisperse hard disks: Using Monte Carlo simulations, we systematically investigate the effect of\nparticle size distribution on the phase behaviour of polydisperse hard disks.\nCompared with the commonly used Gaussian-like polydisperse hard disks [Commun.\nPhys. 2, 70 (2019)], we find that the phase behaviour of polydisperse hard-disk\nsystems with lognormal and triangle distributions are significantly different.\nIn polydisperse hard-disk systems of lognormal distributions, although the\nphase diagram appears similar to that of Gaussian-like polydisperse hard disks,\nthe re-entrant melting of hexatic or solid phase can not be observed in\nsedimentation experiments. For polydisperse hard-disk systems of triangle\ndistributions, the phase behaviour is qualitatively different from the\nGaussian-like and lognormal distributions, and we can not reach any system of\ntrue polydispersity larger than 0.06, which is due to the special shape of the\ntriangle distribution. Our results suggest that the exact particle size\ndistribution is of primary importance in determining the phase behaviour of\npolydisperse hard disks, and we do not have a universal phase diagram for\ndifferent polydisperse hard-disk systems."
    },
    {
        "anchor": "Use of two-particle simulations for the evaluation of the flocculation\n  rate in the case of insurmountable repulsive barriers: The interaction potential between two colloidal particles typically spans a\nfew nanometers. Hence the correct appraisal of the potential in simulations\nrequires very short time steps. However, it is often possible to combine one\nmany-particle calculation with several two-particle simulations in order to\nestimate a set of aggregation rates. As in the theory of Fuchs, this procedure\ncombines the evaluation of the fastest flocculation rate with the calculation\nof several stability ratios. This methodology was already tested in systems\nwhich exhibit low repulsive barriers for primary minimum flocculation. In this\narticle, the procedure is modified in order to calculate an average rate for\nsecondary minimum flocculation. The technique is then used to estimate the\ninfluence of drop deformation on the aggregation rate of hexadecane-in-water\nnano-emulsions stabilized with sodium dodecylsulfate (SDS).",
        "positive": "Evolving Design Rules for the Inverse Granular Packing Problem: If a collection of identical particles is poured into a container, different\nshapes will fill to different densities. But what is the shape that fills a\ncontainer as close as possible to a pre-specified, desired density? We\ndemonstrate a solution to this inverse-packing problem by framing it in the\ncontext of artificial evolution. By representing shapes as bonded spheres, we\nshow how shapes may be mutated, simulated, and selected to produce particularly\ndense or loose packing aggregates, both with and without friction. Moreover, we\nshow how motifs emerge linking these shapes together. The result is a set of\ndesign rules that function as an effective solution to the inverse packing\nproblem for given packing procedures and boundary conditions. Finally, we show\nthat these results are verified by experiments on 3D-printed prototypes used to\nmake packings in the real world."
    },
    {
        "anchor": "Dynamic Glass Transition in Two Dimensions: The question about the existence of a structural glass transition in two\ndimensions is studied using mode coupling theory (MCT). We determine the\nexplicit d-dependence of the memory functional of mode coupling for\none-component systems. Applied to two dimensions we solve the MCT equations\nnumerically for monodisperse hard discs. A dynamic glass transition is found at\na critical packing fraction phi_c^{d=2} = 0.697 which is above phi_c^{d=3} =\n0.516 by about 35%. phi^d_c scales approximately with phi^d_{\\rm rcp} the value\nfor random close packing, at least for d=2, 3. Quantities characterizing the\nlocal, cooperative 'cage motion' do not differ much for d=2 and d=3, and we\ne.g. find the Lindemann criterion for the localization length at the glass\ntransition. The final relaxation obeys the superposition principle, collapsing\nremarkably well onto a Kohlrausch law. The d=2 MCT results are in qualitative\nagreement with existing results from MC and MD simulations. The mean squared\ndisplacements measured experimentally for a quasi-two-dimensional binary system\nof dipolar hard spheres can be described satisfactorily by MCT for monodisperse\nhard discs over four decades in time provided the experimental control\nparameter Gamma (which measures the strength of dipolar interactions) and the\npacking fraction phi are properly related to each other.",
        "positive": "Programming patchy particles to form complex periodic structures: We introduce a scheme to design patchy particles so that a given target\ncrystal is the global free-energy minimum at sufficiently low temperature. A\nkey feature is a torsional component to the potential that only allows binding\nwhen particles have the correct relative orientations. In all examples studied,\nthe target crystal structures readily assembled on annealing from a low-density\nfluid phase, albeit with the simpler target structures assembling more rapidly.\nThe most complex example was a clathrate with 46 particles in its primitive\nunit cell. We also explored whether the structural information encoded in the\nparticle interactions could be further reduced. For example, removing the\ntorsional restrictions led to the assembly of an alternative crystal structure\nfor the BC8-forming design, but the more complex clathrate design was still\nable to assemble because of the greater remaining specificity."
    },
    {
        "anchor": "Unification of Aeolian and Fluvial Sediment Transport Rate from Granular\n  Physics: One of the physically least understood characteristics of geophysical\ntransport of sediments along sediment surfaces is the well known experimental\nobservation that the sediment transport rate $Q$ is linearly dependent on the\nfluid shear stress $\\tau$ applied onto the surface in air, but is nonlinearly\ndependent on $\\tau$ in water. Using transport simulations for a wide range of\ndriving conditions, we show that the scaling depends on the manner in which the\nkinetic fluctuation energy of transported particles is dissipated: via\npredominantly fluid drag and quasistatic contacts (linear) versus fluid drag\nand quasistatic and collisional contacts (nonlinear). We use this finding to\nderive a scaling law (asymptotically $Q\\sim\\tau^2$) in simultaneous agreement\nwith measurements in water and air streams.",
        "positive": "Study of DMPS Monolayers on a Water Substrate with Laboratory X-ray\n  Reflectometer: The molecular structure of dimyristoyl phosphatidylserine (DMPS) monolayers\non a water substrate in different phase states has been investigated under\nnormal conditions by X-ray reflectometry with a photon energy of ~ 8 keV.\nAccording to the experimental data, the transition from a two-dimensional\nexpanded liquid state to a solid gel state (liquid crystal) accompanied by the\nordering of the hydrocarbon tails of the DMPS molecule occurs in the monolayer\nas the surface pressure rises. The monolayer thickness is (20 +/- 3) Angstrom\nand (28 +/- 2) Angstrom in the liquid and solid phases, respectively, with the\ndeflection angle of the molecular tail axis from the normal to the surface in\nthe gel phase being (26 +/- 8) deg. At least a twofold decrease in the degree\nof hydration of the polar lipid groups also occurs under two-dimensional\nmonolayer compression. The reflectometry data have been analyzed using two\napproaches: under the assumption about the presence of two layers with\ndifferent electron densities in the monolayer and without any assumptions about\nthe transverse surface structure. Both approaches demonstrate satisfactory\nagreement between themselves in describing the experimental results."
    },
    {
        "anchor": "Distribution and pressure of active L\u00e9vy swimmers under confinement: Many active matter systems are known to perform L\\'{e}vy walks during\nmigration or foraging. Such superdiffusive transport indicates long-range\ncorrelated dynamics. These behavior patterns have been observed for\nmicroswimmers such as bacteria in microfluidic experiments, where Gaussian\nnoise assumptions are insufficient to explain the data. We introduce\n\\textit{active L\\'evy swimmers} to model such behavior. The focus is on ideal\nswimmers that only interact with the walls but not with each other, which\nreduces to the classical L\\'evy walk model but now under confinement. We study\nthe density distribution in the channel and force exerted on the walls by the\nL\\'evy swimmers, where the boundaries require proper explicit treatment. We\nanalyze stronger confinement via a set of coupled kinetics equations and the\nswimmers' stochastic trajectories. Previous literature demonstrated that\npower-law scaling in a multiscale analysis in free space results in a\nfractional diffusion equation. We show that in a channel, in the weak\nconfinement limit active L\\'evy swimmers are governed by a modified Riesz\nfractional derivative. Leveraging recent results on fractional fluxes, we\nderive steady state solutions for the bulk density distribution of active\nL\\'evy swimmers in a channel, and demonstrate that these solutions agree well\nwith particle simulations. The profiles are non-uniform over the entire domain,\nin contrast to constant-in-the-bulk profiles of active Brownian and\nrun-and-tumble particles. Our theory provides a mathematical framework for\nL\\'evy walks under confinement with sliding no-flux boundary conditions and\nprovides a foundation for studies of interacting active L\\'evy swimmers.",
        "positive": "Casimir effect between pinned particles in two-dimensional jammed\n  systems: The Casimir effect arises when long-ranged fluctuations are geometrically\nconfined between two surfaces, leading to a macroscopic force. Traditionally,\nthese forces have been observed in quantum systems and near critical points in\nclassical systems. Here we show the existence of Casimir-like forces between\ntwo pinned particles immersed in two-dimensional systems near the jamming\ntransition. We observe two components to the total force: a short-ranged,\ndepletion force and a long-ranged, repulsive Casimir-like force. The\nCasimir-like force dominates as the jamming transition is approached, and when\nthe pinned particles are much larger than the ambient jammed particles. We show\nthat this repulsive force arises due to a clustering of particles with strong\ncontact forces around the perimeter of the pinned particles. As the separation\nbetween the pinned particles decreases, a region of high-pressure develops\nbetween them, leading to a net repulsive force."
    },
    {
        "anchor": "Rigidity of Orientationally Ordered Domains of Short Chain Molecules: By molecular dynamics simulation, discovered is a strange rigid-like nature\nfor a hexagonally packed domain of short chain molecules. In spite of the\nnon-bonded short-range interaction potential (Lennard-Jones potential) among\nchain molecules, the packed domain gives rise to a resultant global moment of\ninertia. Accordingly, as two domains encounter obliquely, they rotate so as to\nbe parallel to each other keeping their overall structures as if they were\nrigid bodies.",
        "positive": "Numerical modelling of non-ionic microgels: an overview: Microgels are complex macromolecules. These colloid-sized polymer networks\npossess internal degrees of freedom and, depending on the polymer(s) they are\nmade of, can acquire a responsiveness to variations of the environment\n(temperature, pH, salt concentration, etc.). Besides being valuable for many\npractical applications, microgels are also extremely important to tackle\nfundamental physics problems. As a result, these last years have seen a rapid\ndevelopment of protocols for the synthesis of microgels, and more and more\nresearch has been devoted to the investigation of their bulk properties.\nHowever, from a numerical standpoint the picture is more fragmented, as the\ninherently multi-scale nature of microgels, whose bulk behaviour crucially\ndepends on the microscopic details, cannot be handled at a single level of\ncoarse-graining. Here we present an overview of the methods and models that\nhave been proposed to describe non-ionic microgels at different length-scales,\nfrom the atomistic to the single-particle level. We especially focus on\nmonomer-resolved models, as these have the right level of details to capture\nthe most important properties of microgels, responsiveness and softness. We\nsuggest that these microscopic descriptions, if realistic enough, can be\nemployed as starting points to develop the more coarse-grained representations\nrequired to investigate the behaviour of bulk suspensions."
    },
    {
        "anchor": "Universality of dilute solutions of ring polymers in the thermal\n  crossover region between $\u03b8$ and athermal solvents: Due to their unique topology of having no chain ends, dilute solutions of\nring polymers exhibit behaviour distinct from their linear chain counterparts.\nThe universality of their static and dynamic properties, as a function of\nsolvent quality $z$ in the thermal crossover regime between $\\theta$ and\nathermal solvents, is studied here using Brownian dynamics simulations. The\nuniversal ratio $U_{\\text{RD}}$ of the radius of gyration $R_g$ to the\nhydrodynamic radius $R_H$ is determined, and a comparative study of the\nswelling ratio $\\alpha_g$ of the radius of gyration, the swelling ratio\n$\\alpha_H$ of the hydrodynamic radius, and the swelling ratio $\\alpha_X$ of the\nmean polymer stretch $X$ along the $x$-axis, for linear and ring polymers, is\ncarried out. The ratio $U_{\\text{RD}}$ for dilute ring polymer solutions is\nfound to converge asymptotically to a constant value as $z \\to \\infty$, which\nis a major difference from the behaviour of solutions of linear chains, where\nno such asymptotic limit exists. Additionally, the ratio of the mean stretch\nalong the $x$-axis to the hydrodynamic radius, $(X/R_H)$, is found to be\nindependent of $z$ for polymeric rings, unlike in the case for linear polymers.\nThese results indicate a fundamental difference in the scaling of static and\ndynamic properties of rings and linear chains in the thermal crossover regime.",
        "positive": "Cluster Glasses of Semiflexible Ring Polymers: We present computer simulations of concentrated solutions of unknotted\nnonconcatenated semiflexible ring polymers. Unlike in their flexible\ncounterparts, shrinking involves a strong energetic penalty, favoring\ninterpenetration and clustering of the rings. We investigate the slow dynamics\nof the centers-of-mass of the rings in the amorphous cluster phase, consisting\nof disordered columns of oblate rings penetrated by bundles of prolate ones.\nScattering functions reveal a striking decoupling of self- and collective\nmotions. Correlations between centers-of-mass exhibit slow relaxation, as\nexpected for an incipient glass transition, indicating the dynamic arrest of\nthe cluster positions. However, self-correlations decay at much shorter time\nscales. This feature is a manifestation of the fast, continuous exchange and\ndiffusion of the individual rings over the matrix of clusters. Our results\nreveal a novel scenario of glass-formation in a simple monodisperse system,\ncharacterized by self-collective decoupling, soft caging and mild dynamic\nheterogeneity."
    },
    {
        "anchor": "The relation between stretched-exponential relaxation and the\n  vibrational density of states in glassy disordered systems: Amorphous solids or glasses are known to exhibit stretched-exponential decay\nover broad time intervals in several of their macroscopic observables:\nintermediate scattering function, dielectric relaxation modulus, time-elastic\nmodulus etc. This behaviour is prominent especially near the glass transition.\nIn this Letter we show, on the example of dielectric relaxation, that\nstretched-exponential relaxation is intimately related to the peculiar lattice\ndynamics of glasses. By reformulating the Lorentz model of dielectric matter in\na more general form, we express the dielectric response as a function of the\nvibrational density of states (DOS) for a random assembly of spherical\nparticles interacting harmonically with their nearest-neighbours. Surprisingly\nwe find that near the glass transition for this system (which coincides with\nthe Maxwell rigidity transition), the dielectric relaxation is perfectly\nconsistent with stretched-exponential behaviour with Kohlrausch exponents $0.56\n< \\beta < 0.65$, which is the range where exponents are measured in most\nexperimental systems. Crucially, the root cause of stretched-exponential\nrelaxation can be traced back to soft modes (boson-peak) in the DOS.",
        "positive": "Model for coiling and meandering instability of viscous threads: A numerical model is presented to describe both the transient and\nsteady-state dynamics of viscous threads falling onto a plane. The steady-state\ncoiling frequency w is calculated as a function of fall height H. In the case\nof weak gravity, w ~ H^{-1} and w ~ H are obtained for lower and higher fall\nheights respectively. When the effect of gravity is significant, the relation w\n~ H^2 is observed. These results agree with the scaling laws previously\npredicted. The critical Reynolds number for coil-uncoil transition is\ndiscussed. When the gravity is weak, the transition occurs with hysteresis\neffects. If the plane moves horizontally at a constant speed, a variety of\nmeandering oscillation modes can be observed experimentally. The present model\nalso can describe this phenomenon. The numerically obtained state diagram for\nthe meandering modes qualitatively agrees with the experiment."
    },
    {
        "anchor": "Peptide Folding Kinetics from Replica Exchange Molecular Dynamics: We show how accurate kinetic information, such as the rates of protein\nfolding and unfolding, can be extracted from replica-exchange molecular\ndynamics (REMD) simulations. From the brief and continuous trajectory segments\nbetween replica exchanges, we estimate short-time propagators in conformation\nspace and use them to construct a master equation. For a helical peptide in\nexplicit water, we determine the rates of transitions both locally between\nmicroscopic conformational states and globally for folding and unfolding. We\nshow that accurate rates in the ~1/(100 ns) to ~1/(1 ns) range can be obtained\nfrom REMD with exchange times of 5 ps, in excellent agreement with results from\nlong equilibrium molecular dynamics.",
        "positive": "Circulating Marangoni flows within droplets in smectic films: We present theoretical study and numerical simulation of Marangoni convection\nwithin ellipsoidal isotropic droplets embedded in free standing smectic films\n(FSSF). The thermocapillary flows are analyzed for both isotropic droplets\nspontaneously formed in FSSF overheated above the bulk smectic-isotropic\ntransition, and oil lenses deposited on the surface of the smectic film. The\nrealistic model, for which the upper drop interface is free from the smectic\nlayers, while at the lower drop surface the smectic layering still persists is\nconsidered in detail. For isotropic droplets and oil lenses this leads\neffectively to a sticking of fluid motion at the border with a smectic shell.\nThe above mentioned asymmetric configuration is realized experimentally when\nthe temperature of the upper side of the film is higher than at the lower one.\nThe full set of stationary solutions for Stokes stream functions describing the\nMarangoni convection flows within the ellipsoidal drops were derived\nanalytically. The temperature distribution in the ellipsoidal drop and the\nsurrounding air was determined in the frames of the perturbation theory. As a\nresult the analytical solutions for the stationary thermocapillary convection\nwere derived for different droplet ellipticity ratios and the heat conductivity\nof the liquid crystal and air. In parallel, the numerical hydrodynamic\ncalculations of the thermocapillary motion in the drops were performed. Both\nthe analytical and numerical simulations predict the axially-symmetric\ncirculatory convection motion determined by the Marangoni effect at the droplet\nfree surface. Due to a curvature of the drop interface a temperature gradient\nalong its free surface always persists. Thus, the thermocapillary convection\nwithin the ellipsoidal droplets in overheated FSSF is possible for the\narbitrarily small Marangoni numbers."
    },
    {
        "anchor": "Pore-blockade Times for Field-Driven Polymer Translocation: We study pore blockade times for a translocating polymer of length $N$,\ndriven by a field $E$ across the pore in three dimensions. The polymer performs\nRouse dynamics, i.e., we consider polymer dynamics in the absence of\nhydrodynamical interactions. We find that the typical time the pore remains\nblocked during a translocation event scales as $\\sim N^{(1+2\\nu)/(1+\\nu)}/E$,\nwhere $\\nu\\simeq0.588$ is the Flory exponent for the polymer. In line with our\nprevious work, we show that this scaling behaviour stems from the polymer\ndynamics at the immediate vicinity of the pore -- in particular, the memory\neffects in the polymer chain tension imbalance across the pore. This result,\nalong with the numerical results by several other groups, violates the lower\nbound $\\sim N^{1+\\nu}/E$ suggested earlier in the literature. We discuss why\nthis lower bound is incorrect and show, based on conservation of energy, that\nthe correct lower bound for the pore-blockade time for field-driven\ntranslocation is given by $\\eta N^{2\\nu}/E$, where $\\eta$ is the viscosity of\nthe medium surrounding the polymer.",
        "positive": "The target problem with evanescent subdiffusive traps: We calculate the survival probability of a stationary target in one dimension\nsurrounded by diffusive or subdiffusive traps of time-dependent density. The\nsurvival probability of a target in the presence of traps of constant density\nis known to go to zero as a stretched exponential whose specific power is\ndetermined by the exponent that characterizes the motion of the traps. A\ndensity of traps that grows in time always leads to an asymptotically vanishing\nsurvival probability. Trap evanescence leads to a survival probability of the\ntarget that may be go to zero or to a finite value indicating a probability of\neternal survival, depending on the way in which the traps disappear with time."
    },
    {
        "anchor": "Experimental Observation of Flow Fields Around Active Janus Spheres: The hydrodynamic flow field around a catalytically active colloid is probed\nusing particle tracking velocimetry both in the freely swimming state and when\nkept stationary with an external force. Our measurements provide information\nabout the fluid velocity in the vicinity of the surface of the colloid, and\nconfirm a mechanism for propulsion that was proposed recently. In addition to\noffering a unified understanding of the nonequilibrium interfacial transport\nprocesses at stake, our results open the way to a thorough description of the\nhydrodynamic interactions between such active particles and understanding their\ncollective dynamics.",
        "positive": "Asymptotic analysis of mode-coupling theory of active nonlinear\n  microrheology: We discuss a schematic model of mode-coupling theory for force-driven active\nnonlinear microrheology, where a single probe particle is pulled by a constant\nexternal force through a dense host medium. The model exhibits both a glass\ntransition for the host, and a force-induced delocalization transition, where\nan initially localized probe inside the glassy host attains a nonvanishing\nsteady-state velocity by locally melting the glass. Asymptotic expressions for\nthe transient density correlation functions of the schematic model are derived,\nvalid close to the transition points. There appear several nontrivial time\nscales relevant for the decay laws of the correlators. For the nonlinear\nfriction coeffcient of the probe, the asymptotic expressions cause various\nregimes of power-law variation with the external force, and two-parameter\nscaling laws."
    },
    {
        "anchor": "Theory of elastic interaction between colloidal particles in the nematic\n  cell in the presence of the external electric or magnetic field: The Green function method developed in Ref.[S. B. Chernyshuk and B. I. Lev,\nPhys. Rev. E \\textbf{81}, 041707 (2010)] is used to describe elastic\ninteractions between axially symmetric colloidal particles in the nematic cell\nin the presence of the external electric or magnetic field. General formulas\nfor dipole-dipole, dipole-quadrupole and quadrupole-quadrupole interactions in\nthe homeotropic and planar nematic cells with parallel and perpendicular field\norientations are obtained. A set of new results has been predicted: 1)\n\\textit{Deconfinement effect} for dipole particles in the homeotropic nematic\ncell with negative dielectric anisotropy $\\Delta\\epsilon<0$ and perpendicular\nto the cell electric field, when electric field is approaching it's Frederiks\nthreshold value $E\\Rightarrow E_{c}$. This means cancellation of the\nconfinement effect found in Ref. [M.Vilfan et al. Phys.Rev.Lett. {\\bf 101},\n237801, (2008)] for dipole particles near the Frederiks transition while it\nremains for quadrupole particles. 2) New effect of \\textit{attraction and\nstabilization} of the particles along the electric field parallel to the cell\nplanes in the homeotropic nematic cell with $\\Delta\\epsilon<0$ . The minimun\ndistance between two particles depends on the strength of the field and can be\nordinary for . 3) Attraction and repulsion zones for all elastic interactions\nare changed dramatically under the action of the external field.",
        "positive": "Following the evolution of metastable glassy states under external\n  perturbations: compression and shear-strain: This thesis sums up the research work I performed as a PhD student in\nSapienza Universit\\`a di Roma, and \\'Ecole Normale Sup\\'erieure, Paris, under\nthe joint supervision of Prof. Giorgio Parisi and Dr. Francesco Zamponi. The\nthesis focuses on the theoretical study of metastable glasses prepared through\nnon-equilibrium protocols. The first two chapters contain a review of the\nphenomenology of equilibrium supercooled liquids and non-equilibrium glasses,\nalong with an exposition of the theoretical tools used up to now to approach\nthe glass problem; the third chapter contains a review of the theoretical tools\nwhich are employed in the following of the thesis; the following two chapters\ncontain our main result, namely a mean-field and first-principles theory of\nmetastable glassy states which, as we show, is both able to reproduce known\nobservations and to formulate new predictions and insights into the very nature\nof the glass phase, with tangible consequences in terms of behavior at high\ndensities (or equivalently, low temperatures) and elasto-plastic response under\nstrain; the last two chapters contain a numerical check of some of the results,\nand our conclusions and proposals for further research. The results I report in\nthe present work have been for the most part already published, but here they\nare presented in a consistent and (as much as possible) self-contained manner."
    },
    {
        "anchor": "Curvature-coupling dependence of membrane protein diffusion coefficients: We consider the lateral diffusion of a protein interacting with the curvature\nof the membrane. The interaction energy is minimized if the particle is at a\nmembrane position with a certain curvature that agrees with the spontaneous\ncurvature of the particle. We employ stochastic simulations that take into\naccount both the thermal fluctuations of the membrane and the diffusive\nbehavior of the particle. In this study we neglect the influence of the\nparticle on the membrane dynamics, thus the membrane dynamics agrees with that\nof a freely fluctuating membrane. Overall, we find that this curvature-coupling\nsubstantially enhances the diffusion coefficient. We compare the ratio of the\nprojected or measured diffusion coefficient and the free intramembrane\ndiffusion coefficient, which is a parameter of the simulations, with analytical\nresults that rely on several approximations. We find that the simulations\nalways lead to a somewhat smaller diffusion coefficient than our analytical\napproach. A detailed study of the correlations of the forces acting on the\nparticle indicates that the diffusing inclusion tries to follow favorable\npositions on the membrane, such that forces along the trajectory are on average\nsmaller than they would be for random particle positions.",
        "positive": "Supramolecule Structure for Amphiphilic Molecule by Dissipative Particle\n  Dynamics Simulation: Meso-scale simulation of structure formation for AB-dimers in solution W\nmonomers was performed by dissipative particle dynamics (DPD) algorithm. As a\nsimulation model, modified Jury Model was adopted Jury, S. et al. \"Simulation\nof amphiphilic mesophases using dissipative particle dynamics,\" Phys. Chem.\nChem. Phys. vol.1(1999) pp. 2051-2056, which represents mechanics of\nself-assembly for surfactant hexaethylene glycol dodecyl ether (C12E6) and\nwater(H2 O). The same phase diagram as Jury's result was obtained. We also\nfound that it takes a longer time to form the hexagonal phase (H1) than to form\nthe lamellar phase (Lalpha)."
    },
    {
        "anchor": "Comment on ``Granular Entropy: Explicit Calculations for Planar\n  Assemblies'': A Comment on the Letter by Raphael Blumenfeld and Sam F. Edwards, [Phys. Rev.\nLett. 90, 114303 (2003)].",
        "positive": "Mesoscale simulation of semiflexible chains. II. Evolution dynamics and\n  stability of fiber bundle networks: Network formation of associative semiflexible fibers and mixtures of fibers\nand colloidal particles is simulated for the Johnson-Kendall-Roberts (JKR)\nmodel of elastic contacts, and a phase diagram in terms of particle elasticity\nand surface energy is presented. When fibers self-assemble they form a network\nfor sufficiently large fiber-solvent surface energy. If the surface energy is\nabove the value where single particles crystallize the adhesion forces drive\ndiffusion-limited aggregation. Two mechanisms contribute to coarsening:\nnon-associated chains joining existing bundles, and fiber bundles merging.\nCoarsening stops when the length of the network connections is roughly the\npersistence length, independent of surface energy.\n  If the surface energy is below the value where single particles crystallize,\na network can still be formed but at a much slower (reaction limited) rate.\nLoose (liquid-like) assemblies between chains form when they happen to run\nmore-or-less parallel. These assemblies grow by diffusion and aggregation and\nform a loose network, which sets in micro-phase separation, i.e. syneresis.\nOnly when the clusters crystallize, the coarsening process stops. In this case\nthe length of the network connections is larger than the persistence length of\na single chain, and depends on the value of the surface energy. All networks of\nsemiflexible homopolymers in this study show syneresis. Mixtures of fibers and\ncolloid particles also form fiber bundle networks, but by choosing the colloid\nvolume fraction sufficiently low, swelling gels are obtained. Applications of\nthis model are in biological systems where fibers self-assemble into cell walls\nand bone tissue."
    },
    {
        "anchor": "Shear Melting at the Crystal-Liquid Interface: Erosion and the\n  Asymmetric Suppression of Interface Fluctuations: The influence of an applied shear on the planar crystal-melt interface is\nmodelled by a nonlinear stochastic partial differential equation of the\ninterface fluctuations. A feature of this theory is the asymmetric destruction\nof interface fluctuations due to advection of the crystal protrusions on the\nliquid side of the interface only. We show that this model is able to\nqualitatively reproduce the nonequilibrium coexistence line found in\nsimulations. The impact of shear on spherical clusters is also addressed.",
        "positive": "Self-avoiding knots: Scaling arguments are used to analyze the size of topologically constrained\nclosed ring polymer with excluded volume. It is found that there exists a\nfinite range of polymer thickness (excluded volume) in which self-avoidance is\nunimportant and polymer swelling compared to the Gaussian size is entirely due\nto the topological constraints."
    },
    {
        "anchor": "Aeolian transport layer: We investigate the airborne transport of particles on a granular surface by\nthe saltation mechanism through numerical simulation of particle motion coupled\nwith turbulent flow. We determine the saturated flux $q_{s}$ and show that its\nbehavior is consistent with a classical empirical relation obtained from wind\ntunnel measurements. Our results also allow to propose a new relation valid for\nsmall fluxes, namely, $q_{s}=a(u_{*}-u_{t})^{\\alpha}$, where $u_{*}$ and\n$u_{t}$ are the shear and threshold velocities of the wind, respectively, and\nthe scaling exponent is $\\alpha \\approx 2$. We obtain an expression for the\nvelocity profile of the wind distorted by the particle motion and present a\ndynamical scaling relation. We also find a novel expression for the dependence\nof the height of the saltation layer as function of the wind velocity.",
        "positive": "Distinguishing thixotropy, anti-thixotropy, and viscoelasticity using\n  hysteresis: Thixotropy, anti-thixotropy, and viscoelasticity are three types of\ntime-dependent dynamics that involve fundamentally different underlying\nphysical processes. Yet distinguishing them can be very challenging, which\nhinders the understanding of structure-property relations. Here we show that\nhysteresis is a promising technique to contrast the three dynamics by exploring\nsignatures of the most basic thixotropic, anti-thixotropic, and nonlinear\nviscoelastic models. From these signatures, using shear-rate controlled ramps\nthat begin and end at high shear rates, we identify two distinguishing features\nin hysteresis loops. The first is the direction of the hysteresis loops:\nclockwise for thixotropy, but counterclockwise for viscoelasticity and\nanti-thixotropy. A second feature is achieved at high ramping rates where all\nresponses lose hysteresis: the viscoelastic response shows a stress plateau at\nlow shear rates (lack of stress relaxation), whereas the thixotropic and\nanti-thixotropic responses are purely viscous with minimal shear thinning or\nthickening. The features are observed independent of the model details. We\nestablish further evidence for these signatures by experimentally measuring the\nhysteresis of thixotropic Laponite suspensions, anti-thixotropic carbon black\nsuspensions, and viscoelastic poly (ethylene oxide) solutions. The protocols\nexplored here can be used to distinguish thixotropy, anti-thixotropy, and\nviscoelasticity, which helps reveal the underlying microstructural physics of\ncomplex fluids."
    },
    {
        "anchor": "Liquid-Gas phase transition in Bose-Einstein Condensates with time\n  evolution: We study the effects of a repulsive three-body interaction on a system of\ntrapped ultra-cold atoms in Bose-Einstein condensed state. The stationary\nsolutions of the corresponding $s-$wave non-linear Schr\\\"{o}dinger equation\nsuggest a scenario of first-order liquid-gas phase transition in the condensed\nstate up to a critical strength of the effective three-body force. The time\nevolution of the condensate with feeding process and three-body recombination\nlosses has a new characteristic pattern. Also, the decay time of the dense\n(liquid) phase is longer than expected due to strong oscillations of the\nmean-square-radius.",
        "positive": "Reversible magnetomechanical collapse: virtual touching and detachment\n  of rigid inclusions in a soft elastic matrix: Soft elastic composite materials containing particulate rigid inclusions in a\nsoft elastic matrix are candidates for developing soft actuators or tunable\ndamping devices. The possibility to reversibly drive the rigid inclusions\nwithin such a composite together to a close-to-touching state by an external\nstimulus would offer important benefits. Then, a significant tuning of the\nmechanical properties could be achieved due to the resulting mechanical\nhardening. For a long time, it has been argued whether a virtual touching of\nthe embedded magnetic particles with subsequent detachment can actually be\nobserved in real materials, and if so, whether the process is reversible. Here,\nwe present experimental results that demonstrate this phenomenon in reality.\nOur system consists of two paramagnetic nickel particles embedded at finite\ninitial distance in a soft elastic polymeric gel matrix. Magnetization in an\nexternal magnetic field tunes the magnetic attraction between the particles and\ndrives the process. We quantify the scenario by different theoretical tools,\ni.e., explicit analytical calculations in the framework of linear elasticity\ntheory, a projection onto simplified dipole-spring models, as well as detailed\nfinite-element simulations. From these different approaches, we conclude that\nin our case the cycle of virtual touching and detachment shows hysteretic\nbehavior due to the mutual magnetization between the paramagnetic particles.\nOur results are important for the design and construction of reversibly tunable\nmechanical damping devices. Moreover, our projection on dipole-spring models\nallows the formal connection of our description to various related systems,\ne.g., magnetosome filaments in magnetotactic bacteria."
    },
    {
        "anchor": "Breakup of dense colloidal aggregates under hydrodynamic stresses: Flow-induced aggregation of colloidal particles leads to aggregates with\nfairly high fractal dimension () which are directly responsible for the\nobserved rheological properties of sheared dispersions. We address the problem\nof the decrease of aggregate size with increasing hydrodynamic stress, as a\nconsequence of breakup, by means of a fracture-mechanics model complemented by\nexperiments in a multi-pass extensional (laminar) flow device. Evidence is\nshown that as long as the inner density decay with linear size within the\naggregate (due to fractality) is not negligible (as for), this imposes a\nsubstantial limitation to the hydrodynamic fragmentation process as compared\nwith non-fractal aggregates (where the critical stress is practically\nsize-independent). This is due to the fact that breaking up a fractal object\nleads to denser fractals which better withstand stress. In turbulent flows,\naccounting for intermittency introduces just a small deviation with respect to\nthe laminar case, while the model predictions are equally in good agreement\nwith experiments from the literature. Our findings are summarized in a diagram\nfor the breakup exponent (governing the size versus stress scaling) as a\nfunction of fractal dimension.",
        "positive": "Time Dependent Ginzburg-Landau Equation for Sheared Granular Flow: The time dependent Ginzburg-Landau equation for a two-dimensional granular\nshear flow is numerically solved, where we study both the transient dynamics\nand the steady state of the order parameter. The structural changes of the\nnumerical solutions are qualitatively similar to the shear bands observed in\nthe discrete element method (DEM) simulation of the two-dimensional granular\nshear flow."
    },
    {
        "anchor": "Static and sliding contact of rough surfaces: effect of asperity-scale\n  properties and long-range elastic interactions: Friction in static and sliding contact of rough surfaces is important in\nnumerous physical phenomena. We seek to understand macroscopically observed\nstatic and sliding contact behavior as the collective response of a large\nnumber of microscopic asperities. We develop an efficient numerical framework\nthat can be used to investigate how the macroscopic response of multiple\nfrictional contacts depends on long-range elastic interactions, different\nconstitutive assumptions about the deforming contacts and their local shear\nresistance, and surface roughness. We approximate the contact between two rough\nsurfaces as that between a regular array of discrete deformable elements\nattached to a elastic block and a rigid rough surface. The deformable elements\nare viscoelastic or elasto/viscoplastic with a range of relaxation times, and\nthe elastic interaction between contacts is long-range. We find that the model\nreproduces main macroscopic features of evolution of contact and friction for a\nrange of constitutive models of the elements, suggesting that macroscopic\nfrictional response is robust with respect to the microscopic behavior.\nViscoelasticity/viscoplasticity contributes to the increase of friction with\ncontact time and leads to a subtle history dependence. Interestingly,\nlong-range elastic interactions only change the results quantitatively compared\nto the meanfield response. We find that sustained increase in the static\nfriction coefficient during long hold times suggests viscoelastic response of\nthe underlying material with multiple relaxation time scales. We also find that\nthe experimentally observed proportionality of the direct effect in velocity\njump experiments to the logarithm of the velocity jump points to a complex\nmaterial-dependent shear resistance at the microscale.",
        "positive": "Modeling DNA beacons at the mesoscopic scale: We report model calculations on DNA single strands which describe the\nequilibrium dynamics and kinetics of hairpin formation and melting. Modeling is\nat the level of single bases. Strand rigidity is described in terms of simple\npolymer models; alternative calculations performed using the freely rotating\nchain and the discrete Kratky-Porod models are reported. Stem formation is\nmodeled according to the Peyrard-Bishop-Dauxois Hamiltonian. The kinetics of\nopening and closing is described in terms of a diffusion-controlled motion in\nan effective free energy landscape. Melting profiles, dependence of melting\ntemperature on loop length, and kinetic time scales are in semiquantitative\nagreement with experimental data obtained from fluorescent DNA beacons forming\npoly(T) loops. Variation in strand rigidity is not sufficient to account for\nthe large activation enthalpy of closing and the strong loop length dependence\nobserved in hairpins forming poly(A) loops. Implications for modeling single\nstrands of DNA or RNA are discussed."
    },
    {
        "anchor": "Thermodynamics of mixtures of patchy and spherical colloids of different\n  sizes: a multi-body association theory with complete reference fluid\n  information: We present a theory to predict the structure and thermodynamics of mixtures\nof colloids of different diameters, building on our earlier work [J. Chem.\nPhys. 145, 074904 (2016)] that considered mixtures with all particles\nconstrained to have the same size. The patchy, solvent particles have\nshort-range directional interactions, while the solute particles have\nshort-range isotropic interactions. The hard-sphere mixture without any\nassociation site forms the reference fluid. An important ingredient within the\nmulti-body association theory is the description of clustering of the reference\nsolvent around the reference solute. Here we account for the physical,\nmulti-body clusters of the reference solvent around the reference solute in\nterms of occupancy statistics in a defined observation volume. These occupancy\nprobabilities are obtained from enhanced sampling simulations, but we also\npresent statistical mechanical models to estimate these probabilities with\nlimited simulation data. Relative to an approach that describes only up to\nthree-body correlations in the reference, incorporating the complete reference\ninformation better predicts the bonding state and thermodynamics of the\nphysical solute for a wide range of system conditions. Importantly, analysis of\nthe residual chemical potential of the infinitely dilute solute from molecular\nsimulation and theory shows that whereas the chemical potential is somewhat\ninsensitive to the description of the structure of the reference fluid the\nenergetic and entropic contributions are not, with the results from the\ncomplete reference approach being in better agreement with particle\nsimulations.",
        "positive": "Growth laws and self-similar growth regimes of coarsening\n  two-dimensional foams: Transition from dry to wet limits: We study the topology and geometry of two dimensional coarsening foams with\narbitrary liquid fraction. To interpolate between the dry limit described by\nvon Neumann's law, and the wet limit described by Marqusee equation, the\nrelevant bubble characteristics are the Plateau border radius and a new\nvariable, the effective number of sides. We propose an equation for the\nindividual bubble growth rate as the weighted sum of the growth through\nbubble-bubble interfaces and through bubble-Plateau borders interfaces. The\nresulting prediction is successfully tested, without adjustable parameter,\nusing extensive bidimensional Potts model simulations. Simulations also show\nthat a selfsimilar growth regime is observed at any liquid fraction and\ndetermine how the average size growth exponent, side number distribution and\nrelative size distribution interpolate between the extreme limits. Applications\ninclude concentrated emulsions, grains in polycrystals and other domains with\ncoarsening driven by curvature."
    },
    {
        "anchor": "Symmetric shear banding and swarming vortices in bacterial \"superfluids\": Bacterial suspensions--a premier example of active fluids--show an unusual\nresponse to shear stresses. Instead of increasing the viscosity of the\nsuspending fluid, the emergent collective motions of swimming bacteria can turn\na suspension into a \"superfluid\" with zero apparent viscosity. Although the\nexistence of active \"superfluids\" has been demonstrated in bulk rheological\nmeasurements, the microscopic origin and dynamics of such an exotic phase have\nnot been experimentally probed. Here, using high-speed confocal rheometry, we\nstudy the dynamics of concentrated bacterial suspensions under simple planar\nshear. We find that bacterial \"superfluids\" under shear exhibit unusual\nsymmetric shear bands, defying the conventional wisdom on shear-banding of\ncomplex fluids, where the formation of steady shear bands necessarily breaks\nthe symmetry of unsheared samples. We propose a simple hydrodynamic model based\non the local stress balance and the ergodic sampling of nonequilibrium shear\nconfigurations, which quantitatively describes the observed symmetric\nshear-banding structure. The model also successfully predicts various\ninteresting features of swarming vortices in stationary bacterial suspensions.\nOur study provides new insights into the physical properties of collective\nswarming in active fluids and illustrates their profound influences on\ntransport processes.",
        "positive": "Nucleation of liquid droplets in a fluid with competing interactions: Using a simple density functional theory (DFT) we determine the height of the\nfree energy barrier for forming a droplet of the liquid phase from the\nmetastable gas phase for a model colloidal fluid exhibiting competing\ninteractions. The pair potential has a hard core of diameter {\\sigma}, is\nattractive Yukawa at intermediate separations, and is repulsive Yukawa at large\nseparations. We find that even a very weak long-range repulsive tail in the\npair potential has a profound effect on nucleation: increasing the amplitude of\nthe repulsive Yukawa tail reduces significantly the free energy barrier height\nand therefore increases the liquid droplet nucleation rate. The method we\nintroduce for calculating the droplet density profile and free energy employs a\nfictitious external potential to stabilize a liquid droplet of the desired\nsize, i.e. with a given excess number of particles. For the critical droplet,\ncorresponding to an extremum of the grand potential, this fictitious potential\nis everywhere zero. We examine the decay of the droplet density profiles into\nthe bulk gas. For a range of nucleation state points the DFT predicts\nexponentially damped, long wavelength oscillatory decay for systems exhibiting\nlong-range repulsion, contrasting sharply with the monotonic decay found when\nthe pair potential has only an attractive Yukawa piece. The changes in\nnucleation properties that we find for small amplitudes of the repulsive Yukawa\ntail reflect the propensity of the fluid to form modulated structures such as\nclusters or stripes."
    },
    {
        "anchor": "Flexible filament in time-periodic viscous flow: shape chaos and period\n  three: We study a single, freely--floating, inextensible, elastic filament in a\nlinear shear flow: $\\mathbf{U}_{0}(x,y) = \\dot{\\gamma} y \\hat{x}$. In our\nmodel: the elastic energy depends only on bending; the rate-of-strain,\n$\\dot{\\gamma} = S \\sin(\\omega t)$ is a periodic function of time, $t$; and the\ninteraction between the filament and the flow is approximated by a local\nisotropic drag force. Based on the shape of the filament we find five different\ndynamical phases: straight, buckled, periodic (with period two, period three,\nperiod four, etc), chaotic, and one with chaotic transients. In the chaotic\nphase, we show that the iterative map for the angle, which the end-to-end\nvector of the filament makes with the tangent its one end, has period three\nsolutions; hence it is chaotic. Furthermore, in the chaotic phase the flow is\nan efficient mixer.",
        "positive": "3D DNA origami crystals: Engineering shape and interactions of nanoscopic building blocks allows for\nthe assembly of rationally designed macroscopic three-dimensional (3D)\nmaterials with spatial accuracy inaccessible to top-down fabrication methods.\nOwing to its sequence-specific interaction, DNA is often used as selective\nbinder to connect metallic nanoparticles into highly ordered lattices.\nMoreover, 3D crystals assembled entirely from DNA have been proposed and\nimplemented with the declared goal to arrange guest molecules in predefined\nlattices. This requires design schemes that provide high rigidity and\nsufficiently large open guest space. We here present a DNA origami-based\ntensegrity triangle structure that assembles into a 3D rhombohedral crystalline\nlattice. We site-specifically place 10 nm and 20 nm gold particles within the\nlattice, demonstrating that our crystals are spacious enough to host e.g.\nribosome-sized macromolecules. We validate the accurate assembly of the DNA\norigami lattice itself as well as the precise incorporation of gold particles\nby electron microscopy and small angle X-ray scattering (SAXS) experiments. Our\nresults show that it is possible to create DNA building blocks that assemble\ninto lattices with customized geometry. Site-specific hosting of nano objects\nin the transparent DNA lattice sets the stage for metamaterial and structural\nbiology applications."
    },
    {
        "anchor": "Electrostatic Interactions in Strongly-Coupled Soft Matter: Charged soft-matter systems--such as colloidal dispersions and charged\npolymers--are dominated by attractive forces between constituent like-charged\nparticles when neutralizing counterions of high charge valency are introduced.\nSuch counter-intuitive effects indicate strong electrostatic coupling between\nlike-charged particles, which essentially results from electrostatic\ncorrelations among counterions residing near particle surfaces. In this paper,\nthe attraction mechanism and the structure of counterionic correlations are\ndiscussed in the limit of strong coupling based on recent numerical and\nanalytical investigations and for various geometries (planar, spherical and\ncylindrical) of charged objects.",
        "positive": "Intermolecular adhesion in conjugated polymers: The role of the band gap\n  and solitonic excitations: Conjugated polymers are soft, one-dimensional conductors that admit complex\ninteractions between their polymeric, conformational degrees of freedom and\ntheir electronic ones. The presence of extended electronic states along their\nbackbone allows for inter-chain electronic tunneling at points where these\npolymers make near passes. Using a combination of analytic modeling and\nHartree-Fock numerical calculations, we study the localized electronic states\nthat form due to such close encounters between semiconducting conjugated\npolymers and explore how these states lead to chain--chain binding. We also\nstudy the interaction of these inter-chain binding sites with solitonic\nexcitations on the chains. From these results and a modified Poland-Scheraga\nmodel, we determine the equilibrium structures of paired-chains formed by\nintermolecular electronic tunneling. We calculate the energetic ground state of\nsuch pairs and show the effective thermal persistence length of the paired\nchains can vary over an order of magnitude due to the intermolecular binding\nmechanism."
    },
    {
        "anchor": "Proteotronics: Electronic devices based on proteins: The convergent interests of different scientific disciplines, from\nbiochemistry to electronics, toward the investigation of protein electrical\nproperties, has promoted the development of a novel bailiwick, the so called\nproteotronics. The main aim of proteotronics is to propose and achieve\ninnovative electronic devices, based on the selective action of specific\nproteins. This paper gives a sketch of the fields of applications of\nproteotronics, by using as significant example the detection of a specific\nodorant molecule carried out by an olfactory receptor. The experiment is\nbriefly reviewed and its theoretical interpretation given. Further experiments\nare envisioned and expected results discussed in the perspective of an\nexperimental validation.",
        "positive": "Effect of Heat Treatment Mode and Aggressive Media on Mechanical\n  Properties of Porous Polytetrafluoroethylene Membranes Fabricated via\n  Electrospinning: Electrospinning is a modern alternative to the expanded method for producing\nporous polytetrafluoroethylene membranes. High strength and relative\nelongation, as well as the ability to maintain these properties for a long time\nwhen exposed to aggressive media at high temperatures, determine the\napplication scope of the electrospun polytetrafluoroethylene membranes. Herein,\nwe report the effect of polytetrafluoroethylene suspension content in the\nspinning solution, heat treatment mode (quenching and annealing) and aggressive\nmedia at high temperatures on the tensile strength and relative elongation of\nelectrospun polytetrafluoroethylene membranes. Membranes fabricated from\nspinning solutions with 50 to 60 wt % polytetrafluoroethylene suspension\ncontent that underwent quenching were characterized by the highest tensile\nstrength and relative elongation. Electrospun polytetrafluoroethylene membranes\nalso demonstrated high chemical resistance to concentrated mineral acids and\nalkalis, a bipolar aprotic solvent, engine oil and deionized water at 100 deg\nfor 48 hours."
    },
    {
        "anchor": "Elastic interface acoustic waves in twinned crystals: A new type of Interface Acoustic Waves (IAW) is presented, for single-crystal\northotropic twins bonded symmetrically along a plane containing only one common\ncrystallographic axis. The effective boundary conditions show that the waves\nare linearly polarized at the interface, either transversally or\nlongitudinally. Then the secular equation is obtained in full analytical form\nusing new relationships for the displacement-traction quadrivector at the\ninterface. For Gallium Arsenide and for Silicon, it is found that the IAWs with\ntransverse (resp. longitudinal) polarization at the interface are of the\nStoneley (resp. leaky) type.",
        "positive": "Critical pore radius and transport properties of disordered hard- and\n  overlapping-sphere models: Descriptors that characterize the geometry and topology of the pore space of\nporous media are intimately linked to their transport properties. We quantify\nsuch descriptors, including pore-size functions and the critical pore radius\n$\\delta_c$, for four different models: maximally random jammed sphere packings,\noverlapping spheres, equilibrium hard spheres, and inherent structures of the\nquantizer energy. For precise estimates of the percolation thresholds, we use a\nstrict relation of the void percolation around sphere configurations to\nweighted bond percolation on the corresponding Voronoi networks. We use the\nNewman-Ziff algorithm to determine the percolation threshold using universal\nproperties of the cluster size distribution. Often, $\\delta_c$ is used as the\nkey characteristic length scale that determines the fluid permeability $k$. A\nrecent study [Torquato. Adv. Wat. Resour. 140, 103565 (2020)] suggested for\nporous media with a well-connected pore space an alternative estimate of $k$\nbased on the second moment of the pore size $\\langle\\delta^2\\rangle$. Here, we\nconfirm that, for all porosities and all models considered, $\\delta_c^2$ is to\na good approximation proportional to $\\langle\\delta^2\\rangle$. However, unlike\n$\\langle\\delta^2\\rangle$, the permeability estimate based on $\\delta_c^2$ does\nnot predict the correct ranking of $k$ for our models. Thus, we confirm\n$\\langle\\delta^2\\rangle$ to be a promising candidate for convenient and\nreliable estimates of $k$ for porous media with a well-connected pore space.\nMoreover, we compare the fluid permeability of our models with varying degrees\nof order, as measured by the $\\tau$ order metric. We find that (effectively)\nhyperuniform models tend to have lower values of $k$ than their nonhyperuniform\ncounterparts. Our findings could facilitate the design of porous media with\ndesirable transport properties via targeted pore statistics."
    },
    {
        "anchor": "Site-Specific Colloidal Crystal Nucleation by Template-enhanced Particle\n  Transport: The monomer surface mobility is the single most important parameter that\ndecides the nucleation density and morphology of islands during thin film\ngrowth. During template-assisted surface growth in particular, low surface\nmobilities can prevent monomers from reaching target sites and this results in\na partial to complete loss of nucleation control. While in atomic systems a\nbroad range of surface mobilities can be readily accessed, for colloids, owing\nto their large size, this window is substantially narrow and therefore imposes\nsevere restrictions in extending template-assisted growth techniques to steer\ntheir self-assembly. Here, we circumvented this fundamental limitation by\ndesigning templates with spatially varying feature sizes, in this case moire\npatterns, which in the presence of short-range depletion attraction presented\nsurface energy gradients for the diffusing colloids. The templates serve a dual\npurpose, first, directing the particles to target sites by enhancing their\nsurface mean free paths and second, dictating the size and symmetry of the\ngrowing crystallites. Using optical microscopy, we directly followed the\nnucleation and growth kinetics of colloidal islands on these surfaces at the\nsingle-particle level. We demonstrate nucleation control, with high fidelity,\nin a regime that has remained unaccessed in theoretical, numerical and\nexperimental studies on atoms and molecules as well. Our findings pave the way\nfor fabricating non-trivial surface architectures composed of complex colloids\nand nanoparticles.",
        "positive": "Hydroelastomers: soft, tough, highly swelling composites: Inspired by the cellular design of plant tissue, we present a new approach to\nmake versatile, tough, highly water-swelling composites. We embed highly\nswelling hydrogel particles inside tough, water-permeable, elastomeric\nmatrices. The resulting composites, which we call \\emph{hydroelastomers}, show\nlittle softening as they swell, and have excellent fracture properties that\nmatch those of the best-performing, tough hydrogels. Our composites are\nstraightforward to fabricate, based on commercial materials, and can easily be\nmolded or extruded to form shapes with complex swelling geometries.\nFurthermore, there is a large design space available for making\nhydroelastomers, since one can use any hydrogel as the dispersed phase in the\ncomposite, including hydrogels with stimuli-responsiveness. These features\nshould make hydroelastomers excellent candidates for use in soft robotics and\nswelling-based actuation, or as shape-morphing materials, while also being\nuseful as hydrogel replacements in a wide range of other fields."
    },
    {
        "anchor": "Forces and fluctuations in planar, spherical and tubular membranes: Lipid membranes constitute very particular materials: on the one hand, they\nbreak very easily under microscopical stretching; on the other hand, they are\nextremely flexible, presenting deformations even at small scales. Consequently,\na piece of membrane has an area excess relative to its optically resolvable\narea, also called projected area. From a mechanical point of view, we can thus\nidentify three tensions associated to lipid membranes: the mechanical effective\ntension $\\tau$, associated to an increase in the projected area and to the\nflattening of the fluctuations; the tension $\\sigma$, associated to the\nmicroscopical area of the membrane and thus non measurable, but commonly used\nin theoretical predictions; and its macroscopical counterpart measured through\nthe fluctuation spectrum, $r$. Up to now, the equality between these quantities\nwas taken for granted when analyzing experimental data. In this dissertation,\nwe have studied, using the projected stress tensor, whether and under which\nconditions it is justified to assume $\\tau = \\sigma$. We studied three\ngeometries (planar, spherical and cylindrical) and obtained the relation $\\tau\n\\approx \\sigma - \\sigma_0$, where $\\sigma_0$ is a constant depending only on\nthe membrane's high frequency cutoff and on the temperature. Accordingly, we\nconclude that neglecting the difference between $\\tau$ and $\\sigma$ is\njustifiable only to membranes under large tensions: in the case of small\ntensions, corrections must be taken into account. We have studied the\nimplications of this result to the interpretation of experiments involving\nmembrane nanotubes. Regarding $r$, we have questioned a former demonstration\nconcerning its equality with $\\tau$. Finally, the force fluctuation for planar\nmembranes and membrane nanotubes was quantified for the first time.",
        "positive": "Microscopic field theory for structure formation in systems of\n  self-propelled particles with generic torques: We derive a dynamical field theory for self-propelled particles subjected to\ngeneric torques and forces by explicitly coarse-graining their microscopic\ndynamics, described by a many-body Fokker-Planck equation. The model includes\nboth intrinsic torques inducing self-rotation, as well as interparticle torques\nleading to, for instance, the local alignment of particles' orientations.\nWithin this approach, although the functional form of the pairwise interactions\ndoes not need to be specified, one can directly map the parameters of the field\ntheory onto the parameters of particle-based models. We perform a linear\nstability analysis of the homogeneous solution of the field equations and find\nboth long-wavelength and short-wavelength instabilities. The former signals the\nemergence of a macroscopic structure, which we associate with motility-induced\nphase separation, while the second one signals the growth of a finite structure\nwith a characteristic size. Intrinsic torques hinder phase separation, pushing\nthe onset of the long-wavelength instability to higher activities. Further,\nthey generate finite-sized structures with a characteristic size proportional\nto both the self-propulsion velocity and the inverse of the self-rotation\nfrequency. Our results show that a general mechanism might explain why\nchirality tends to suppress motility-induced phase separation but instead\npromotes the formation of non-equilibrium patterns."
    },
    {
        "anchor": "Vortex formation in a slowly rotating Bose-Einstein condensate confined\n  in a harmonic-plus-gaussian laser trap: Motivated by the recent experiment at ENS [ V. Bretin, S. Stock, Y. Seurin\nand, J. Dalibard, Phys. Rev. Lett. {\\bf 92}, 050403 (2004)], we study a\nrotating (non-)interacting atomic Bose-Einstein condensate confined in a\nharmonic-plus-gaussian laser trap potential. By adjusting the amplitude of the\nlaser potential, one can make quadratic-plus-quartic potential,purely quartic\npotential, and quartic-minus-quadratic potential. We show that an interacting\nBose-Einstein condensate confined in a harmonic-plus-gaussian laser trap breaks\nthe rotational symmetry of the Hamiltonian when rotational frequency is greater\nthan one-half of the lowest energy surface mode frequency. We also show that by\nincreasing the amplitude of the gaussian laser trap, a vortex appears in a\nslowly rotating Bose-Einstein condensate. Moreover, one can also create a\nvortex in non-interacting Bose-Einstein condensate confined in\nharmonic-plus-gaussian laser potential.",
        "positive": "Using Limited Neural Networks to Assess Relative Mechanistic Influence\n  on Shock Heating in Granular Solids: The rapid compaction of granular media results in localized heating that can\ninduce chemical reactions, phase transformations, and melting. However, there\nare numerous mechanisms in play that can be dependent on a variety of\nmicrostructural features. Machine learning techniques such as neural networks\noffer a ubiquitous method to develop models for physical processes. Limiting\nwhat kinds of microstructural information is used as input and assessing\nnormalized changes in network error, the relative importance of different\nmechanisms can be inferred. Here we utilize binned, initial density information\nas network inputs to predict local shock heating in a granular high explosive\ntrained from large scale, molecular dynamics simulations. The spatial extend of\nthe density field used in the network is altered to assess the importance and\nrelevant length scales of the physical mechanisms in play, where different\nmicrostructural features result in different predictive capability."
    },
    {
        "anchor": "Splay nematic phase: Different liquid crystalline phases with long-range orientational but not\npositional order, so-called nematic phases, are scarce. It rarely occurs that a\nnew nematic phase is discovered and such event is inevitably accompanied by a\ngreat interest. Here, we describe a transition from uniaxial to novel nematic\nphase characterized by a periodic splay modulation of the director. In this new\nnematic phase, defect structures not present in the uniaxial nematic are\nobserved, which indicates that the new phase has lower symmetry than the\nordinary nematic phase. The phase transition is weakly first order with a\nsignificant pretransitional behavior, which manifests as strong splay\nfluctuations. When approaching the phase transition, the splay nematic constant\nis unusually low and goes towards zero. Analogously to the transition from the\nuniaxial nematic to the twist-bend nematic phase, this transition is driven by\ninstability towards splay orientational deformation, resulting in a\nperiodically splayed structure. And, similarly, a Landau-de Gennes type of\nphenomenological theory can be used to describe the phase transition. The\nmodulated splay phase is biaxial and antiferroelectric.",
        "positive": "Experimental investigations on the nonequilibrium dynamics of pattern\n  formation in fluid and granular systems: Patterns are quotidian in nature. Distinct multiscale patterns are generally\na consequence of nonequilibrium dynamical processes associated with mechanical\nor hydrodynamic instabilities. In this thesis, I report experimental\ninvestigations on pattern formation in a few examples of fluid and granular\nsystems, and uncover the underlying mechanisms that give rise to those\npatterns.\n  Leidenfrost drops are known to experience star-shaped oscillations with\nlittle damping. However, the underlying mechanism remains unclear. Here I\nreport that the hydrodynamic coupling between the rapid evaporated vapor flow\nand vapor-liquid interface excites the star-shaped oscillations, suggesting a\npurely hydrodynamic origin.\n  Polygonal desiccation crack patterns are commonly observed in natural\nsystems. However, it is unclear whether similar crack patterns spanning\nmultiple length scales share the same underlying physics. I report experimental\nresults on polygonal cracks in drying suspensions of micron-sized particles. In\ncornstarch-water mixtures, multi-scale crack patterns were observed due to two\ndistinct desiccation mechanisms. We also find the characteristic area of the\npolygonal cracks, and film thickness obey a universal power law.\n  Finally, I report sedimentations of non-Brownian particles in viscous fluids.\nWe observed an effective repulsion between particles with nonuniform density in\nboth two-body and many-body systems in two and three dimensions, in contrast to\nparticles with uniform density. We also characterize the statistical properties\nof the sedimentation patterns of particles in three dimensions.\n  The patterns I report in this thesis represent typical examples in fluid and\ngranular systems that are driven by nonequilibrium dynamics, and the underlying\nmechanisms we uncover are expected to enhance our understanding of how these\nseemingly simple patterns arise in natural systems."
    },
    {
        "anchor": "Molecular Dynamics at Low Time Resolution: The internal dynamics of macro-molecular systems is characterized by widely\nseparated time scales, ranging from fraction of ps to ns. In ordinary molecular\ndynamics simulations, the elementary time step dt used to integrate the\nequation of motion needs to be chosen much smaller of the shortest time scale,\nin order not to cut-off important physical effects. We show that, in systems\nobeying the over-damped Langevin Eq., the fast molecular dynamics which occurs\nat time scales smaller than dt can be analytically integrated out and gives\nraise to a time-dependent correction to the diffusion coefficient, which we\nrigorously compute. The resulting effective Langevin equation describes by\nconstruction the same long-time dynamics, but has a lower time resolution\npower, hence it can be integrated using larger time steps dt. We illustrate and\nvalidate this method by studying the diffusion of a point-particle in a\none-dimensional toy-model and the denaturation of a protein.",
        "positive": "Emergence of stable and fast folding protein structures: The number of protein structures is far less than the number of sequences. By\nimposing simple generic features of proteins (low energy and compaction) on all\npossible sequences we show that the structure space is sparse compared to the\nsequence space. Even though the sequence space grows exponentially with N (the\nnumber of amino acids) we conjecture that the number of low energy compact\nstructures only scales as ln N. This implies that many sequences must map onto\ncountable number of basins in the structure space. The number of sequences for\nwhich a given fold emerges as a native structure is further reduced by the dual\nrequirements of stability and kinetic accessibility. The factor that determines\nthe dual requirement is related to the sequence dependent temperatures,\nT_\\theta (collapse transition temperature) and T_F (folding transition\ntemperature). Sequences, for which \\sigma =(T_\\theta-T_F)/T_\\theta is small,\ntypically fold fast by generically collapsing to the native-like structures and\nthen rapidly assembling to the native state. Such sequences satisfy the dual\nrequirements over a wide temperature range. We also suggest that the functional\nrequirement may further reduce the number of sequences that are biologically\ncompetent. The scheme developed here for thinning of the sequence space that\nleads to foldable structures arises naturally using simple physical\ncharacteristics of proteins. The reduction in sequence space leading to the\nemergence of foldable structures is demonstrated using lattice models of\nproteins."
    },
    {
        "anchor": "Osmotic pressure between arbitrarily charged surfaces: a revisited\n  approach: The properties of ionic solutions between charged surfaces are often studied\nwithin the Poisson-Boltzmann framework, by finding the electrostatic potential\nprofile. For example, the osmotic pressure between two charged planar surfaces\ncan be evaluated by solving coupled equations for the electrostatic potential\nand osmotic pressure. Such a solution relies on symmetry arguments and is\nrestricted to either equally or oppositely charged surfaces. Here, we provide a\ndifferent and more efficient scheme to derive the osmotic pressure\nstraight-forwardly, without the need to find the electrostatic potential\nprofile. We derive analytical expressions for the osmotic pressure in terms of\nthe inter-surface separation, salt concentration, and arbitrary boundary\nconditions. Such results should be useful in force measurement setups, where\nthe force is measured between two differently prepared surfaces, or between two\nsurfaces held at a fixed potential difference. The proposed method can be\nsystematically used for generalized Poisson-Boltzmann theories in planar\ngeometries, as is demonstrated for the sterically modified Poisson-Boltzmann\ntheory.",
        "positive": "On the Extension Behavior of Helicogenic Polypeptides: The force laws governing the extension behavior of homopolypeptides are\nobtained from a phenomenological free energy capable of describing the\nhelix-coil transition. Just above the melting temperature of the free chains,\nT*, the plot of force, f, vs. end-to-end distance, R, exhibits two plateaus\nassociated with coexistence of helical and coil domains. The lower plateau is\ndue to tension induced onset of helix-coil transition. The higher plateau\ncorresponds to the melting of the helices by overextension. Just below T* the\nf-R plot exhibits only the upper plateau. The f-R plots, the helical fraction,\nthe number of domains and their polydispersity are calculated for two models:\nIn one the helical domains are viewed as rigid rods while in the second they\nare treated as worm like chains."
    },
    {
        "anchor": "Liquid exfoliation of multilayer graphene in sheared solvents: a\n  molecular dynamics investigation: Liquid-phase exfoliation, the use of a sheared liquid to delaminate graphite\ninto few-layer graphene, is a promising technique for the large-scale\nproduction of graphene. But the micro and nanoscale fluid-structure processes\ncontrolling the exfoliation are not fully understood. Here we perform\nnon-equilibrium molecular dynamics simulations of a defect-free graphite\nnanoplatelet suspended in a shear flow and measure the critical shear rate\n$\\dot \\gamma_c$ needed for the exfoliation to occur. We compare $\\dot \\gamma_c$\nfor different solvents including water and NMP, and nanoplatelets of different\nlengths. Using a theoretical model based on a balance between the work done by\nviscous shearing forces and the change in interfacial energies upon layer\nsliding, we are able to predict the critical shear rates $\\dot \\gamma_c$\nmeasured in simulations. We find that an accurate prediction of the exfoliation\nof short graphite nanoplatelets is possible only if both hydrodynamic slip and\nthe fluid forces on the graphene edges are considered, and if an accurate value\nof the solid-liquid surface energy is used. The commonly used \"geometric-mean\"\napproximation for the solid-liquid energy leads to grossly incorrect\npredictions.",
        "positive": "Avalanche contribution to shear modulus of granular materials: Shear modulus of frictionless granular materials near the jamming transition\nunder oscillatory shear is numerically investigated. It is found that the shear\nmodulus $G$ satisfies a scaling law to interpolate between $G \\sim (\\phi -\n\\phi_J)^{1/2}$ and $G \\sim \\gamma_0^{-1/2}(\\phi-\\phi_J)$ for a linear spring\nmodel of the elastic interaction between contacting grains, where $\\phi$,\n$\\phi_J$, and $\\gamma_0$ are, respectively, the volume fraction of grains, the\nfraction at the jamming point, and the amplitude of the oscillatory shear. The\nlinear relation between the shear modulus and $\\phi - \\phi_J$ can be understood\nby slip avalanches."
    },
    {
        "anchor": "Collective dynamics and shattering of disturbed two-dimensional\n  Lennard-Jones crystals: Elucidating collective dynamics in crystalline systems is a common scientific\nquestion in multiple fields. In this work, by combination of high-precision\nnumerical approach and analytical normal mode analysis, we systematically\ninvestigate the dynamical response of two-dimensional Lennard-Jones crystal as\na purely classical mechanical system under random disturbance of varying\nstrength, and reveal rich microscopic dynamics. Specifically, we observe highly\nsymmetric velocity field composed of sharply divided coherent and disordered\nregions, and identify the order-disorder dynamical transition of the velocity\nfield. Under stronger disturbance, we reveal the vacancy-driven shattering of\nthe crystal. This featured disruption mode is fundamentally different from the\ndislocation-unbinding scenario in two-dimensional melting. We also examine the\nhealing dynamics associated with vacancies of varying size. The results in this\nwork advance our understanding about the formation of collective dynamics and\ncrystal disruption, and may have implications in elucidating relevant\nnon-equilibrium behaviors in a host of crystalline systems.",
        "positive": "Casimir Effect in Fluids above the Isotropic-Lamellar Transition: We study fluctuation-induced interaction in confined fluids above the\nisotropic-lamellar transition. At an ideal continuous transition, the\ndisjoining pressure has the asymptotic form $\\Pi(d\\to\\infty)\\approx -C k_BT\nq_0^2/d$, where $d$ is the interwall distance, $q_0$ is the wavenumber of the\nscattering peak, and $C= 1/(4\\pi)$ in the strong anchoring limit. The\nlong-rangedness is enhanced due to continuous distribution of soft modes in the\n${\\bf q}$-space. An unconventionally strong Casimir force with a range of\nseveral lamella thicknesses is realistic above the transition. We also find an\noscillatory force profile near a surface-induced transition."
    },
    {
        "anchor": "Colloidal dynamics in polymer solutions: Optical two-point microrheology\n  measurements: We present an extension of the two-point optical microrheology technique\nintroduced by Crocker \\textit{et al.} [Phys. Rev. Lett. \\textbf{85}, 888\n(2000)] to high frequencies. The correlated fluctuations of two probe spheres\nheld by a pair of optical tweezers within a viscoelastic medium are determined\nusing optical interferometry. A theoretical model is developed to yield the\nfrequency-dependent one- and two-particle response functions from the\ncorrelated motion. We demonstrate the validity of this method by determining\nthe one- and two-particle correlations in a semi-dilute solution of polystyrene\nin decalin. We find that the ratio of the one- and two-particle response\nfunctions is anomalous which we interpret as evidence for a slip boundary\ncondition caused by depletion of polymer from the surface of the particle.",
        "positive": "Nonequilibrium dynamics in an amorphous solid: The non-equilibrium dynamics of an amorphous solid is studied with a\nsoft-spin type model. We show that the aging behavior in the glassy state\nfollows a modified Kohlrausch-Williams-Watts (KWW) form similar to that\nobtained in Phys. Rev. Lett. {\\bf 95}, 055702 (2005) from analysis of the\ndielectric loss data. The nature of the fluctuation-dissipation theorem (FDT)\nviolation is also studied in the time as well as correlation windows."
    },
    {
        "anchor": "Fluctuation mediated interactions due to rigidity mismatch and their\n  effect on miscibility of lipid mixtures in multicomponent membranes: We consider how membrane fluctuations can modify the miscibility of lipid\nmixtures, that is to say how the phase diagram of a boundary-constrained\nmembrane is modified when the membrane is allowed to fluctuate freely in the\ncase of zero surface tension. In order for fluctuations to have an effect, the\ndifferent lipid types must have differing Gaussian rigidities. We show,\nsomewhat paradoxically, that fluctuation-induced interactions can be treated\napproximately in a mean-field type theory. Our calculations predict that,\ndepending on the difference in bending and Gaussian rigidity of the lipids,\nmembrane fluctuations can either favor or disfavor mixing.",
        "positive": "How Flow Changes Polymer Depletion in a Slit: A theoretical model is developed for predicting dynamic polymer depletion\neffects under the influence of fluid flow. The results are established by\ncombining the two-fluid model and the self-consistent field theory. We consider\na uniform fluid flow across a slit containing a solution with polymer chains.\nThe two parallel and infinitely long walls are permeable to solvent only and\nthe polymers do not adsorb to these walls. For a weak flow and a narrow slit in\nTheta-solvent conditions, an analytic expression is derived to describe the\nsteady state polymer concentration profiles. In both Theta- and good-solvents,\nwe compute the time evolution of the concentration profiles for various flow\nrates characterized by the Peclet number. The model reveals the interplay of\ndepletion, solvent condition, slit width, and relative strength of the fluid\nflow."
    },
    {
        "anchor": "Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon\n  Gas Diffusion NMR Studies of Porous Media: We have extended the utility of NMR as a technique to probe porous media\nstructure over length scales of ~ 100 - 2000 micron by using the spin 1/2 noble\ngas 129Xe imbibed into the system's pore space. Such length scales are much\ngreater than can be probed with NMR diffusion studies of water-saturated porous\nmedia. We utilized Pulsed Gradient Spin Echo NMR measurements of the\ntime-dependent diffusion coefficient, D(t) of the xenon gas filling the pore\nspace to study further the measurements of both the surface area-pore volume\nratio, S/Vp, and the tortuosity (pore connectivity) of the medium. In\nuniform-size glass bead packs, we observed D(t) decreasing with increasing t,\nreaching an observed asymptote of ~ 0.62 - 0.65D0, that could be measured over\ndiffusion distances extending over multiple bead diameters. Measurements of\nD(t)/D0 at differing gas pressures showed this tortuosity limit was not\naffected by changing the characteristic diffusion length of the spins during\nthe diffusion encoding gradient pulse. This was not the case at the short time\nlimit, where D(t)/D0 was noticeably affected by the gas pressure in the sample.\nIncreasing the gas pressure, and hence reducing D0 and the diffusion during the\ngradient pulse served to reduce the previously observed deviation of D(t)/D0\nfrom the S/Vp relation. The Pade approximation is used to interpolate between\nthe long and short time limits in D(t). While the short time D(t) point lay\nabove the interpolation line in the case of small beads, due to diffusion\nduring the gradient pulse on the order of the pore size, it was also noted that\nthe experimental D(t) data fell below the Pade line in the case of large beads,\nmost likely due to finite size effects.",
        "positive": "Coarse-grained dynamics of transiently-bound fast linkers: Transient bonds between fast linkers and slower particles are widespread in\nphysical and biological systems. In spite of their diverse structure and\nfunction, a commonality is that the linkers diffuse on timescales much faster\ncompared to the overall motion of the particles they bind to. This limits\nnumerical and theoretical approaches that need to resolve these diverse\ntimescales with high accuracy. Many models, therefore, resort to effective, yet\nad-hoc, dynamics, where linker motion is only accounted for when bound. This\npaper provides a mathematical justification for such coarse-grained dynamics\nthat preserves detailed balance at equilibrium. Our derivation is based on\nmultiscale averaging techniques and is broadly applicable. We verify our\nresults with simulations on a minimal model of fast linker binding to a slow\nparticle. We show how our framework can be applied to various systems,\nincluding those with multiple linkers, stiffening linkers upon binding, or slip\nbonds with force-dependent unbinding. Importantly, the preservation of detailed\nbalance only sets the ratio of the binding to the unbinding rates, but it does\nnot constrain the detailed expression of binding kinetics. We conclude by\ndiscussing how various choices of binding kinetics may affect macroscopic\ndynamics."
    },
    {
        "anchor": "Crack patterns in drying protein solution drops: A deposited drop of bovine serum albumin salt solution experiences both\ngelation and fracturation during evaporation. The cracks appearing at the edge\nof the gelling drop are regularly spaced, due to the competition between the\nevaporation-induced and relaxation-induced stress evolution. Subsequently, the\nmean crack spacing evolves in an unexpected way, being inversely proportional\ninstead of proportional to the deposit thickness. This evolution has been\nascribed to the change with time of the average shrinkage stress, the crack\npatterning being purely elastic instead of evaporation-controlled.",
        "positive": "Shape transitions of high-genus fluid vesicles: The morphologies of genus-2 to -8 fluid vesicles are studied by using\ndynamically triangulated membrane simulations with area-difference elasticity.\nIt is revealed that the alignments of the membrane pores alter the vesicle\nshapes and the types of shape transitions for the genus $g \\ge 3$. At a high\nreduced volume, a stomatocyte with a circular alignment of $g+1$ pores\ncontinuously transforms into a discocyte with a line of $g$ pores with\nincreasing intrinsic area difference. In contrast, at a low volume, a\nstomatocyte transforms into a ($g+1$)-hedral shape and subsequently exhibits a\ndiscrete phase transition to a discocyte."
    },
    {
        "anchor": "Elastocapillary deformations on partially-wetting substrates: rival\n  contact-line models: A partially-wetting liquid can deform the underlying elastic substrate upon\nwhich it rests. This situation requires the development of theoretical models\nto describe the wetting forces imparted by the drop onto the solid substrate,\nparticularly those at the contact-line. We construct a general solution using a\ndisplacement potential function for the elastic deformations within a finite\nelastic substrate associated with these wetting forces, and compare the results\nfor several different contact-line models. Our work incorporates internal\ncontributions to the surface stress from both liquid/solid $\\Sigma_{ls}$ and\nsolid/gas $\\Sigma_{sg}$ solid surface tensions (surface stress), which results\nin a non-standard boundary-value problem that we solve using a dual integral\nequation. We compare our results to relevant experiments and conclude that the\ngeneralization of solid surface tension $\\Sigma_{ls} \\neq \\Sigma_{sg}$ is an\nessential feature in any model of partial-wetting. The comparisons also allow\nus to systematically eliminate some proposed contact-line models.",
        "positive": "Self-organization of active colloids mediated by chemical interactions: Self-propelled colloidal particles exhibit rich non-equilibrium phenomena and\nhave promising applications in fields such as drug delivery and self-assembled\nactive materials. Previous experimental and theoretical studies have shown that\nchemically active colloids that consume or produce a chemical can self-organize\ninto clusters with diverse characteristics depending on the effective phoretic\ninteractions. In this paper, we investigate self-organization in systems with\nmultiple chemical species that undergo a network of reactions and multiple\ncolloidal species that participate in different reactions. Active colloids\npropelled by complex chemical reactions with potentially nonlinear kinetics can\nbe realized using enzymatic reactions that occur on the surface of\nenzyme-coated particles. To demonstrate how the self-organizing behavior\ndepends on the chemical reactions active colloids catalyze and their chemical\nenvironment, we consider first a single type of colloid undergoing a simple\ncatalytic reaction, and compare this often-studied case with self-organization\nin binary mixtures of colloids with sequential reactions, and binary mixtures\nwith nonlinear autocatalytic reactions. Our results show that in general active\ncolloids at low particle densities can form localized clusters in the presence\nof bulk chemical reactions and phoretic attractions. The characteristics of the\nclusters, however, depend on the reaction kinetics in the bulk and on the\nparticles and phoretic coefficients. With one or two chemical species that only\nundergo surface reactions, the space for possible self-organizations are\nlimited. By considering the additional system parameters that enter the\nchemical reaction network involving reactions on the colloids and in the fluid,\nthe design space of colloidal self-organization can be enlarged, leading to a\nvariety of non-equilibrium structures."
    },
    {
        "anchor": "Motile dislocations knead odd crystals into whorls: The competition between thermal fluctuations and potential forces is the\nfoundation of our understanding of phase transitions and matter in equilibrium.\nDriving matter out of equilibrium allows for a new class of interactions which\nare neither attractive nor repulsive but transverse. The existence of such\ntransverse forces immediately raises the question of how they interfere with\nbasic principles of material self-organization. Despite a recent surge of\ninterest, this question remains open. Here, we show that activating transverse\nforces by homogeneous rotation of colloidal units generically turns otherwise\nquiescent solids into a crystal whorl state dynamically shaped by\nself-propelled dislocations. Simulations of both a minimal model and a full\nhydrodynamics model establish the generic nature of the chaotic dynamics of\nthese self-kneading polycrystals. Using a continuum theory, we explain how odd\nand Hall stresses conspire to destabilize chiral crystals from within. This\nchiral instability produces dislocations that are unbound by their\nself-propulsion. Their proliferation eventually leads to a crystalline whorl\nstate out of reach of equilibrium matter.",
        "positive": "Sympathetic cooling of trapped fermions by bosons in the presence of\n  particle losses: We study the sympathetic cooling of a trapped Fermi gas interacting with an\nideal Bose gas below the critical temperature of the Bose-Einstein\ncondensation. We derive the quantum master equation, which describes the\ndynamics of the fermionic component, and postulating the thermal distribution\nfor both gases we calculate analytically the rate at which fermions are cooled\nby the bosonic atoms. The particle losses constitute an important source of\nheating of the degenerate Fermi gas. We evaluate the rate of loss-induced\nheating and derive analytical results for the final temperature of fermions,\nwhich is limited in the presence of particle losses."
    },
    {
        "anchor": "Using isosbestic points to extract interactions from structure factors: Inverting scattering experiments to obtain effective interparticle\ninteractions for particles in solution is generally a poorly conditioned\nproblem. More accurate potentials can be obtained through the use of isosbestic\npoints, values of k where the scattering intensity I(k) or the structure factor\nS(k) is invariant to changes in potential well-depth. These points also suggest\na new extended corresponding states principle for particles in solution based\non the particle density or packing fraction, the second osmotic virial\ncoefficient, and a new measure of potential range.",
        "positive": "Melting and re-entrant melting of polydisperse hard disks: Because of long-wavelength fluctuations, the nature of solids and phase\ntransitions in 2D are different from those in 3D systems, and have been heavily\ndebated in past decades, in which the focus was on the existence of hexatic\nphase. Here, by using large scale computer simulations, we investigate the\nmelting transition in 2D systems of polydisperse hard disks. We find that, with\nincreasing the particle size polydispersity, the melting transition can be\nqualitatively changed from the recently proposed two-stage process to the\nKosterlitz-Thouless-Halperin-Nelson-Young scenario with significantly enlarged\nstability range for hexatic phase. Moreover, re-entrant melting transitions are\nfound in high density systems of polydisperse hard disks, which were proven\nimpossible in 3D polydisperse hard-sphere systems. These suggest a new\nfundamental difference between phase transitions in polydisperse systems in 2D\nand 3D."
    },
    {
        "anchor": "Dynamics of poroelastic filaments: We investigate the stability and geometrically non-linear dynamics of slender\nrods made of a linear isotropic poroelastic material. Dimensional reduction\nleads to the evolution equation for the shape of the poroelastica where, in\naddition to the usual terms for the bending of an elastic rod, we find a term\nthat arises from fluid-solid interaction. Using the poroelastica equation as a\nstarting point, we consider the load controlled and displacement controlled\nplanar buckling of a slender rod, as well as the closely related instabilities\nof a rod subject to twisting moments and compression when embedded in an\nelastic medium. This work has applications to the active and passive mechanics\nof thin filaments and sheets made from gels, plant organs such as stems, roots\nand leaves, sponges, cartilage layers and bones.",
        "positive": "Influence of hydrodynamics on many-particle diffusion in 2D colloidal\n  suspensions: We study many-particle diffusion in 2D colloidal suspensions with full\nhydrodynamic interactions through a novel mesoscopic simulation technique. We\nfocus on the behaviour of the effective scaled tracer and collective diffusion\ncoefficients $D_T(\\rho) / D_0$ and $D_C(\\rho) / D_0$, where $D_0$ is the\nsingle-particle diffusion coefficient, as a function of the density of the\ncolloids $\\rho$. At low Schmidt numbers $Sc={\\cal O}(1)$, we find that\nhydrodynamics has essentially no effect on the behaviour of $D_T(\\rho)/D_0$. At\nlarger $Sc$, $D_T(\\rho)/D_0$ is enhanced at all densities, although the\ndifferences compared to the case without hydrodynamics are minor. The\ncollective diffusion coefficient, on the other hand, is much more strongly\ncoupled to hydrodynamical conservation laws and is distinctly different from\nthe purely dissipative case."
    },
    {
        "anchor": "Collective stiffening of soft hair assemblies: Many living systems use assemblies of soft and slender structures whose\ndeflections allow them to mechanically probe their immediate environment. In\nthis work, we study the collective response of artificial soft hair assemblies\nto a shear flow by imaging their deflections. At all hair densities, the\ndeflection is found to be proportional to the local shear stress with a\nproportionality factor that decreases with density. The measured collective\nstiffening of hairs is modeled both with a microscopic elastohydrodynamic model\nthat takes into account long range hydrodynamic hair-hair interactions and a\nphenomenological model that treats the hair assemblies as an effective porous\nmedium. While the microscopic model is in reasonable agreement with the\nexperiments at low hair density, the phenomenological model is found to be\npredictive across the entire density range.",
        "positive": "Universal relaxation dynamics of sphere packings below jamming: We show that non-Brownian suspensions of repulsive spheres below jamming\ndisplay a slow relaxational dynamics with a characteristic time scale that\ndiverges at jamming. This slow time scale is fully encoded in the structure of\nthe unjammed packing and can be readily measured via the vibrational density of\nstates. We show that the corresponding dynamic critical exponent is the same\nfor randomly generated and sheared packings. Our results show that a wide\nvariety of physical situations, from suspension rheology to algorithmic studies\nof the jamming transition are controlled by a unique diverging timescale, with\na universal critical exponent."
    },
    {
        "anchor": "Incorporating tunability into a universal scaling framework for shear\n  thickening: Recently, we proposed a universal scaling framework that shows shear\nthickening in dense suspensions is governed by the crossover between two\ncritical points: one associated with frictionless isotropic jamming and a\nsecond corresponding to frictional shear jamming. Here, we show that orthogonal\nperturbations to the flows, an effective method for tuning shear thickening,\ncan also be folded into this universal scaling framework. Specifically, we show\nthat the effect of adding in orthogonal shear perturbations (OSP) can be\nincorporated by simply altering the scaling variable to include a\nmultiplicative term that decreases with the normalized OSP strain rate. These\nresults demonstrate the broad applicability of our scaling framework, and\nillustrate how it can be modified to incorporate other complex flow fields.",
        "positive": "Hopping in a Supercooled Lennard-Jones Liquid: Metabasins, Waiting Time\n  Distribution, and Diffusion: We investigate the jump motion among potential energy minima of a\nLennard-Jones model glass former by extensive computer simulation. From the\ntime series of minima energies, it becomes clear that the energy landscape is\norganized in superstructures, called metabasins. We show that diffusion can be\npictured as a random walk among metabasins, and that the whole temperature\ndependence resides in the distribution of waiting times. The waiting time\ndistribution exhibits algebraic decays: $\\tau^{-1/2}$ for very short times and\n$\\tau^{-\\alpha}$ for longer times, where $\\alpha\\approx2$ near $T_c$. We\ndemonstrate that solely the waiting times in the very stable basins account for\nthe temperature dependence of the diffusion constant."
    },
    {
        "anchor": "Spectral responses in granular compaction: The slow compaction of a gently tapped granular packing is reminiscent of the\nlow-temperature dynamics of structural and spin glasses. Here, I probe the\ndynamical spectrum of granular compaction by measuring a complex\n(frequency-dependent) volumetric susceptibility $\\tilde{\\chi}_v$. While the\npacking density $\\rho$ displays glass-like slow relaxations (aging) and\nhistory-dependence (memory) at low tapping amplitudes, the susceptibility\n$\\tilde{\\chi}_v$ displays very weak aging effects, and its spectrum shows no\nsign of a rapidly growing timescale. These features place $\\tilde{\\chi}_v$ in\nsharp contrast to its dielectric and magnetic counterparts in structural and\nspin glasses; instead, $\\tilde\\chi_v$ bears close similarities to the complex\nspecific heat of spin glasses. This, I suggest, indicates the glass-like\ndynamics in granular compaction are governed by statistically rare relaxation\nprocesses that become increasingly separated in timescale from the typical\nrelaxations of the system. Finally, I examine the effect of finite system size\non the spectrum of compaction dynamics. Starting from the ansatz that low\nfrequency processes correspond to large scale particle rearrangements, I\nsuggest the observed finite size effects are consistent with the suppression of\nlarge-scale collective rearrangements in small systems.",
        "positive": "A simulational and theoretical study of the spherical electrical double\n  layer for a size-asymmetric electrolyte: the case of big coions: Monte Carlo simulations of a spherical macroion, surrounded by a\nsize-asymmetric electrolyte in the primitive model, were performed. We\nconsidered 1:1 and 2:2 salts with a size ratio of 2 (i.e., with coions twice\nthe size of counterions), for several surface charge densities of the\nmacrosphere. The radial distribution functions, electrostatic potential at the\nHelmholtz surfaces, and integrated charge are reported. We compare these\nsimulational data with original results obtained from the Ornstein-Zernike\nintegral equation, supplemented by the hypernetted chain/hypernetted chain\n(HNC/HNC) and hypernetted chain/mean spherical approximation (HNC/MSA)\nclosures, and with the corresponding calculations using the modified\nGouy-Chapman and unequal-radius modified Gouy-Chapman theories. The HNC/HNC and\nHNC/MSA integral equations formalisms show good concordance with Monte Carlo\n\"experiments\", whereas the notable limitations of point-ion approaches are\nevidenced. Most importantly, the simulations confirm our previous theoretical\npredictions of the non-dominance of the counterions in the size-asymmetric\nspherical electrical double layer [J. Chem. Phys. 123, 034703 (2005)], the\nappearance of anomalous curvatures at the outer Helmholtz plane and the\nenhancement of charge reversal and screening at high colloidal surface charge\ndensities due to the ionic size asymmetry."
    },
    {
        "anchor": "Topological vacancies in spherical crystal clusters: Understanding geometric frustration of ordered phases in two-dimensional\ncondensed matters on curved surfaces is closely related to a host of scientific\nproblems in condensed matter physics and materials science. Here we show how\ntwo-dimensional Lennard-Jones crystal clusters confined on a sphere resolve the\ngeometric frustration and lead to pentagonal vacancy structures. These\nvacancies, originated from the combination of curvature and physical\ninteraction, are found to be topological defects and they can be further\nclassified into dislocational and disclinational types. We analyze the dual\nrole of these crystallographic defects as both vacancies and topological\ndefects, illustrate their formation mechanism, and present the phase diagram.\nThe revealed dual role of the topological vacancies may find applications in\nthe fabrication of robust nanopores. This work also suggests the promising\npotential of exploiting the richness in both physical interactions and\nsubstrate geometries to create new types of crystallographic defects, which\nhave strong connections with the design of crystalline materials.",
        "positive": "Connecting discrete particle mechanics to continuum granular\n  micromechanics: Anisotropic continuum properties under compaction: A systematic and mechanistic connection between granular materials'\nmacroscopic and grain level behaviors is developed for monodisperse systems of\nspherical elastic particles under die compaction. The Granular Micromechanics\nApproach (GMA) with static assumption is used to derive the stiffness tensor of\ntransversely isotropic materials, from the average behavior of\nparticle-particle interactions in all different directions at the microscale.\nTwo particle-scale directional density distribution functions, namely the\ndirectional distribution of a combined mechano-geometrical property and the\ndirectional distribution of a purely geometrical property, are proposed and\nparametrized by five independent parameters. Five independent components of the\nsymmetrized tangent stiffness tensor are also determined from discrete particle\nmechanics (PMA) calculations of nine perturbations around points of the loading\npath. Finally, optimal values for these five GMA parameters were obtained by\nminimizing the error between PMA calculations and GMA closed-form predictions\nof stiffness tensor during the compaction process. The results show that GMA\nwith static assumption is effective at capturing the anisotropic evolution of\nmicrostructure during loading, even without describing contacts independently\nbut rather accounting for them in an average sense."
    },
    {
        "anchor": "The Biaxial Smectic-A* Phase -- A New Phase, Already But Unknowingly\n  Discovered?: The biaxial smectic-A* (Sm-A_B*) phase, appearing in the phase sequence\nSm-A*--Sm-A*_B--Sm-C*, is analyzed using Landau theory. It is found to possess\na helical superstructure with a pitch that is significantly shorter than the\npitch of the Sm-C* helical superstructure. The Sm-A_B*--Sm-C* transition can be\neither 1st or 2nd order, and correspondingly there will be either a jump or\ncontinuous variation in the pitch. The behaviors of the birefringence and\nelectroclinic effect are analyzed and found to be similar to those of a\nSm-C*_alpha phase. As such, it is possible that the Sm-A_B* phase could be\nmisidentified as a Sm-C*alpha phase. Ways to distinguish the two phases are\ndiscussed.",
        "positive": "Fluid-driven traveling waves in soft robots: Many marine creatures, gastropods, and earthworms generate continuous\ntraveling waves in their bodies for locomotion within marine environments,\ncomplex surfaces, and inside narrow gaps. In this work, we study theoretically\nand experimentally the use of embedded pneumatic networks as a mechanism to\nmimic nature and generate bi-directional traveling waves in soft robots. We\napply long-wave approximation to theoretically calculate the required\ndistribution of pneumatic network and inlet pressure oscillations needed to\ncreate desired moving wave patterns. We then fabricate soft robots with\ninternal pneumatic network geometry based on these analytical results. The\nexperimental results agree well with our model and demonstrate the propagation\nof moving waves in soft robots, along with locomotion capabilities. The\npresented results allow fabricating soft robots capable of continuous moving\nwaves via the common approach of embedded pneumatic networks and requiring only\ntwo input controls."
    },
    {
        "anchor": "Permeation through a lamellar stack of lipid mixtures: We study material transport and permeation through a lamellar stack of\nmulti-component lipid membranes by performing Monte Carlo simulations of a\nstacked two-dimensional Ising model in presence of permeants. In the model,\npermeants are transported through the stack via in-plane lipid clusters, which\nare inter-connected in the vertical direction. These clusters are formed\ntransiently by concentration fluctuations of the lipid mixture, and the\npermeation process is affected, especially close to the critical temperature of\nthe binary mixture. We show that the permeation rate decays exponentially as\nfunction of temperature and permeant lateral size, whereas the dependency on\nthe characteristic waiting time obeys a stretched exponential function. The\nmaterial transport through such lipid clusters can be significantly affected\naround physiological temperatures.",
        "positive": "The Rheology of Granular Mixtures with Varying Size, Density, Particle\n  Friction and Flow Geometry: Employing the discrete element method, we study the rheology of dense\ngranular media mixtures, varying in size, density, and frictional properties of\nparticles, across a spectrum from quasi-static to inertial regimes. By\naccounting for the volumetric contribution of each solid phase, we find that\nthe stress ratio, $\\mu$, and concentration $\\phi$, scale with the inertial\nnumber when using volume averaging to calculate mean particle density, friction\nand size. Moreover, the critical packing fraction correlates with skewness,\npolydispersity, and particle friction, irrespective of the size distribution.\nNotably, following the work of Kim and Kamrin [2020] we introduce a rheological\npower-law scaling to collapse all or monodisperse and polydisperse data,\nreliant on concentration, dimensionless granular temperature, and the inertial\nnumber. This model seamlessly merges the $\\mu(I)$-rheology and Kinetic Theory,\nenabling the unification of all local and non-local rheology data onto a single\nmaster curve."
    },
    {
        "anchor": "Analysis of Granular Packing Structure by Scattering of THz Radiation: Scattering methods are widespread used to characterize the structure and\nconstituents of matter on small length scales. This motivates this introductory\ntext on identifying prospective approaches to scattering-based methods for\ngranular media. A survey to light scattering by particles and particle\nensembles is given. It is elaborated why the established scattering methods\nusing X-rays and visible light cannot in general be transferred to granular\nmedia. Spectroscopic measurements using Terahertz radiation are highlighted as\nthey to probe the scattering properties of granular media, which are sensitive\nto the packing structure. Experimental details to optimize spectrometer for\nmeasurements on granular media are discussed. We perform transmission\nmeasurements on static and agitated granular media using Fourier-transform\nspectroscopy at the THz beamline of the BessyII storage ring. The measurements\ndemonstrate the potential to evaluate degrees of order in the media and to\ntrack transient structural states in agitated bulk granular media.",
        "positive": "Laser induced quasicrystalline order in charge stabilised colloidal\n  systems: We have studied the ordering of a two dimensional charge stabilised colloidal\nsystem in the presence of a stationary one dimensionally modulated laser field\nformed by the superposition of two modulations with wavevectors $q_0 \\tau$ and\n$q_0/\\tau$, where $q_0$ is the wavevector corresponding to the first peak of\nthe direct correlation function of the unperturbed liquid, and $\\tau$ is the\ngolden mean. In the framework of the Landau-Alexander-McTague theory we find\nthat a decagonal quasicrystalline phase is stabler than the liquid or the\ntriangular lattice in certain regions of the phase diagram. Our study also\nshows a reentrant melting phenomena for larger laser field strengths. We find\nthat the transition from the modulated liquid to the quasicrystalline phase is\ncontinuous in contrast to a first order transition from the modulated liquid to\nthe triangular crystalline phase."
    },
    {
        "anchor": "Non-Newtonian viscosity of E-coli suspensions: The viscosity of an active suspension of E-Coli bacteria is determined\nexperimentally in the dilute and semi dilute regime using a Y shaped\nmicro-fluidic channel. From the position of the interface between the pure\nsuspending fluid and the suspension, we identify rheo-thickening and\nrheo-thinning regimes as well as situations at low shear rate where the\nviscosity of the bacteria suspension can be lower than the viscosity of the\nsuspending fluid. In addition, bacteria concentration and velocity profiles in\nthe bulk are directly measured in the micro-channel.",
        "positive": "Curvature condensation and bifurcation in an elastic shell: We study the formation and evolution of localized geometrical defects in an\nindented cylindrical elastic shell using a combination of experiment and\nnumerical simulation. We find that as a symmetric localized indentation on a\nsemi-cylindrical shell increases, there is a transition from a global mode of\ndeformation to a localized one which leads to the condensation of curvature\nalong a symmetric parabolic crease. This process introduces a soft mode in the\nsystem, converting a load-bearing structure into a hinged, kinematic mechanism.\nFurther indentation leads to twinning wherein the parabolic crease bifurcates\ninto two creases that move apart on either side of the line of symmetry. A\nqualitative theory captures the main features of the phenomena and leads to\nsharper questions about the nucleation of these defects."
    },
    {
        "anchor": "Mechanisms in the size segregation of a binary granular mixture: A granular mixture of particles of two sizes that is shaken vertically will\nin most cases segregate. If the larger particles accumulate at the top of the\nsample, this is called the Brazil-nut effect (BNE); if they accumulate at the\nbottom, the reverse Brazil-nut effect (RBNE). While this process is of great\nindustrial importance in the handling of bulk solids, it is not well\nunderstood. In recent years ten different mechanisms have been suggested to\nexplain when each type of segregation is observed. However, the dependence of\nthe mechanisms on driving conditions and material parameters and hence their\nrelative importance is largely unknown. In this paper we present experiments\nand simulations where both types of particles are made from the same material\nand shaken under low air pressure, which reduces the number of mechanisms to be\nconsidered to seven. We observe both BNE and RBNE by varying systematically the\ndriving frequency and amplitude, diameter ratio, ratio of total volume of small\nto large particles, and overall sample volume. All our results can be explained\nby a combination of three mechanisms: a geometrical mechanism called void\nfilling, transport of particles in sidewall-driven convection rolls, and\nthermal diffusion, a mechanism predicted by kinetic theory.",
        "positive": "Effects of particle-size ratio on jamming of binary mixtures: We perform a systematic numerical study of the effects of the particle-size\nratio $R \\ge 1$ on the properties of jammed binary mixtures. We find that\nchanging $R$ does not qualitatively affect the critical scaling of the pressure\nand coordination number with the compression near the jamming transition, but\nthe critical volume fraction at the jamming transition varies with $R$.\nMoreover, the static structure factor (density correlation) $S(k)$ strongly\ndepends on $R$ and shows distinct long wave-length behaviors between large and\nsmall particles. Thus the previously reported behavior of $S(k)\\sim k$ in the\nlong wave-length limit is only a special case in the $R\\to 1$ limit, and cannot\nbe simply generalized to jammed systems with $R>1$."
    },
    {
        "anchor": "Confinement of semiflexible polymers: A variational framework is developed to examine the equilibrium states of a\nsemi-flexible polymer that is constrained to lie on a fixed surface. As an\napplication the confinement of a closed polymer loop of fixed length $2\\pi R$\nwithin a spherical cavity of smaller radius, $R_0$, is considered. It is shown\nthat an infinite number of distinct periodic completely attached equilibrium\nstates exist, labeled by two integers: $n=2,3,4,...$ and $p=1,2,3,...$, the\nnumber of periods of the polar and azimuthal angles respectively. Small loops\noscillate about a geodesic circle: $n=2$, $p=1$ is the stable ground state;\nstates with higher $n$ exhibit instabilities. If $R\\ge 2R_0$ new states appear\nas oscillations about a doubly covered geodesic circle; the state $n=3, p=2$\nreplaces the two-fold as the ground state in a finite band of values of $R$.\nWith increasing $R$, loop states alternate between orbital behavior as the\npoles are crossed and oscillatory behavior upon collapse to a multiple cover of\na geodesic circle, (signalled respectively by an increase in $p$ and an\nincrease in $n$). The force transmitted to the surface does not increase\nmonotonically with loop size, but does asymptotically. It behaves\ndiscontinuously where $n$ changes. The contribution to energy from geodesic\ncurvature is bounded. In large loops, the energy becomes dominated by a state\nindependent contribution proportional to the loop size; the energy gap between\nthe ground state and excited states disappears.",
        "positive": "Mixing--Demixing Transition in Polymer-Grafted Spherical Nanoparticles: Polymer-grafted nanoparticles (PGNPs) can provide property profiles than\ncannot be obtained individually by polymers or nanoparticles (NPs). Here, we\nhave studied the mixing--demixing transition of symmetric copolymer melts of\npolymer-grafted spherical nanoparticles by means of coarse-grained molecular\ndynamics simulation and a theoretical mean-field model. We find that a larger\nsize of NPs leads to higher stability for given number of grafted chains and\nchain length reaching a point where demixing is not possible. Most importantly,\nthe increase in the number of grafted chains, $N_g$, can initially favour the\nphase separation of PGNPs, but further increase can lead to more difficult\ndemixing. The reason is the increasing impact of an effective core that forms\nas the grafting density of the tethered polymer chains around the NPs\nincreases. The range and exact values of $N_g$ where this change in behaviour\ntakes place depends on the NP size and the chain length of the grafted polymer\nchains. Our study elucidates the phase behaviour of PGNPs and in particular the\ninfluence of the grafting density on the phase behaviour of the systems\nanticipating that it will open new doors in the understanding of these systems\nwith implications in materials science and medicine."
    },
    {
        "anchor": "Coupling topological defect phase to extrinsic curvature in nematic\n  shells: In two dimensional nematics, topological defects are point like singularities\nwith both a charge and a phase. We study topological defects within curved\nnematic textures on the surface of a cylinder. This allows us to isolate the\neffect of extrinsic curvature on the structure of the topological defect. By\nminimizing the energy associated with distortions in the nematic director\naround the core of a defect we show that the phase of the topological defect is\ncoupled to the orientation of the cylinder. This coupling depends on the\nrelative energetic cost associated with splay, bend and twist distortions of\nthe nematic director. We identify a bistability in the phase of the defects\nwhen twist deformations dominate. Finally, we show a similar effect for integer\ncharge topological defects.",
        "positive": "High order elastic terms, boojums and general paradigm of the elastic\n  interaction between colloidal particles in the nematic liquid crystals: Theoretical description of the elastic interaction between colloidal\nparticles in NLC with incorporation of the higher order elastic terms beyond\nthe limit of dipole and qudrupole interactions is proposed. The expression for\nthe elastic interaction potential between axially symmetric colloidal\nparticles, taking into account of the high order elastic terms, is obtained.\nThe general paradigm of the elastic interaction between colloidal particles in\nNLC is proposed so that every particle with strong anchoring and radius $a$ has\nthree zones surrounding itself. The first zone for $a<r\\lessapprox 1.3a$ is the\nzone of topological defects; the second zone at the approximate distance range\n$1.3a \\lessapprox r \\lessapprox 4a$ is the zone where crossover from\ntopological defects to the main multipole moment takes place. The higher order\nelastic terms are essential nere (from 10% to 60% of the total deformation).\nThe third zone is the zone of the main multipole moment, where higher order\nterms make a contribution of less than 10%. This zone extends to distances\n$r\\gtrapprox 4a=2D$.\n  The case of spherical particles with planar anchoring conditions and boojums\nat the poles is considered as an example. It is found that boojums can be\ndescribed analitically via multipole expansion with accuracy up to $1/r^{7}$\nand the whole spherical particle can be effectively considered as the multipole\nof the order 6 with multipolarity equal $2^{6}=64$. The correspondent elastic\ninteraction with higher order elastic terms gives the angle\n$\\theta_{min}=34.5^{\\circ}$ of minimum energy between two contact beads which\nis close to the experimental value of $\\theta_{min}=30^{\\circ}$."
    },
    {
        "anchor": "Equation of state, structure and diffusion coefficients of Gay-Berne\n  fluids: the cases $\u03ba'$ = 5; 10; 15; 20: We performed extensive molecular dynamics simulations to obtain\npressure-density phase diagram, orientational order parameter, pair correlation\nfunctions and translational diffusion coefficients of Gay-Berne fluids.\nDifferent sets of parameters were employed for the Gay-Berne potential, in\nparticular we studied the cases $\\kappa'=5, 10, 15, 20$ and $\\kappa=3$,\n$\\mu=2$, $\\nu=1$ at different conditions of density and temperature. The\nstructure was analyzed in terms of the order parameter and the pair correlation\nfunctions. We found that for the highest value $\\kappa'=20$ the region where\npressure increases with density is significantly reduced at low temperatures;\nadditionally the pressure shows several decays with density as an indicative\nthat several structural phases can take place. These effects are discussed in\nterms of the pair correlation functions. For higher temperatures the pressure\nshows only two decays for all $\\kappa'$'s studied. As this parameter increases\nits value those decays are shifted to lower densities.",
        "positive": "Wetting, roughness and hydrodynamic slip: The hydrodynamic slippage at a solid-liquid interface is currently at the\ncenter of our understanding of fluid mechanics. For hundreds of years this\nscience has relied upon no-slip boundary conditions at the solid-liquid\ninterface that has been applied successfully to model many macroscopic\nexperiments, and the state of this interface has played a minor role in\ndetermining the flow. However, the problem is not that simple and has been\nrevisited recently. Due to the change in the properties of the interface, such\nas wettability and roughness, this classical boundary condition could be\nviolated, leading to a hydrodynamic slip. In this chapter, we review recent\nadvances in the understanding and expectations for the hydrodynamic boundary\nconditions in different situations, by focussing mostly on key papers from past\ndecade. We highlight mostly the impact of hydrophobicity, roughness, and\nespecially their combination on the flow properties. In particular, we show\nthat hydrophobic slippage can be dramatically affected by the presence of\nroughness, by inducing novel hydrodynamic phenomena, such as giant interfacial\nslip, superfluidity, mixing, and low hydrodynamic drag. Promising directions\nfor further research are also discussed."
    },
    {
        "anchor": "Moment free energies for polydisperse systems: A polydisperse system contains particles with at least one attribute $\\sigma$\n(such as particle size in colloids or chain length in polymers) which takes\nvalues in a continuous range. It therefore has an infinite number of conserved\ndensities, described by a density {\\em distribution} $\\rho(\\sigma)$. The free\nenergy depends on all details of $\\rho(\\sigma)$, making the analysis of phase\nequilibria in such systems intractable. However, in many (especially\nmean-field) models the {\\em excess} free energy only depends on a finite number\nof (generalized) moments of $\\rho(\\sigma)$; we call these models truncatable.\nWe show, for these models, how to derive approximate expressions for the {\\em\ntotal} free energy which only depend on such moment densities. Our treatment\nunifies and explores in detail two recent separate proposals by the authors for\nthe construction of such moment free energies. We show that even though the\nmoment free energy only depends on a finite number of density variables, it\ngives the same spinodals and critical points as the original free energy and\nalso correctly locates the onset of phase coexistence. Results from the moment\nfree energy for the coexistence of two or more phases occupying comparable\nvolumes are only approximate, but can be refined arbitrarily by retaining\nadditional moment densities. Applications to Flory-Huggins theory for\nlength-polydisperse homopolymers, and for chemically polydisperse copolymers,\nshow that the moment free energy approach is computationally robust and gives\nnew geometrical insights into the thermodynamics of polydispersity.",
        "positive": "Extended law of corresponding states for protein solutions: The so-called extended law of corresponding states, as proposed by Noro and\nFrenkel [J. Chem. Phys. 113, 2941 (2000)], involves a mapping of the phase\nbehaviors of systems with short-range attractive interactions. While it has\nalready extensively been applied to various model potentials, here we test its\napplicability to protein solutions with their complex interactions. We\nsuccessfully map their experimentally determined metastable gas--liquid\nbinodals, as available in the literature, to the binodals of short-range\nsquare-well fluids, as determined by previous as well as new Monte Carlo\nsimulations. This is achieved by representing the binodals as a function of the\ntemperature scaled with the critical temperature (or as a function of the\nreduced second virial coefficient) and the concentration scaled by the cube of\nan effective particle diameter, where the scalings take into account the\nattractive and repulsive contributions to the interaction potential,\nrespectively. The scaled binodals of the protein solutions coincide with\nsimulation data of the adhesive hard-sphere fluid. Furthermore, once the\nrepulsive contributions are taken into account by the effective particle\ndiameter, the temperature dependence of the reduced second virial coefficients\nfollows a master curve that corresponds to a linear temperature dependence of\nthe depth of the square-well potential. We moreover demonstrate that, based on\nthis approach and cloud-point measurements only, second virial coefficients can\nbe estimated, which we show to agree with values determined by light scattering\nor by DLVO-based calculations."
    },
    {
        "anchor": "Front speed and pattern selection of a propagating chemical front in an\n  active fluid: Spontaneous pattern formation in living systems is driven by\nreaction-diffusion chemistry and active mechanics. The feedback between\nchemical and mechanical forces is often essential to robust pattern formation,\nyet it remains poorly understood in general. In this analytical and numerical\npaper, we study an experimentally-motivated minimal model of coupling between\nreaction-diffusion and active matter: a propagating front of an autocatalytic\nand stress-generating species. In the absence of activity, the front is\ndescribed by the the well-studied KPP equation. We find that front propagation\nis maintained even in active systems, with crucial differences: an extensile\nstress increases the front speed beyond a critical magnitude of the stress,\nwhile a contractile stress has no effect on the front speed but can generate a\nperiodic instability in the high-concentration region behind the front. We\nexpect our results to be useful in interpreting pattern formation in active\nsystems with mechano-chemical coupling in vivo and in vitro.",
        "positive": "Noninvasive Measurement of Dissipation in Colloidal Systems: According to Harada and Sasa [Phys. Rev. Lett. 95, 130602 (2005)], heat\nproduction generated in a non-equilibrium steady state can be inferred from\nmeasuring response and correlation functions. In many colloidal systems,\nhowever, it is a nontrivial task to determine response functions, whereas\ndetails about spatial steady state trajectories are easily accessible. Using a\nsimple conditional averaging procedure, we show how this fact can be exploited\nto reliably evaluate average heat production. We test this method using\nBrownian dynamics simulations, and apply it to experimental data of an\ninteracting driven colloidal system."
    },
    {
        "anchor": "Complex coupling between surface charge and thermo-osmotic phenomena: Thermo-osmotic flows, generated at liquid-solid interfaces by thermal\ngradients, can be used to produce electric currents from waste heat on charged\nsurfaces. The two key parameters controlling the thermo-osmotic current are the\nsurface charge and the interfacial enthalpy excess due to liquid-solid\ninteractions. While it has been shown that the contribution from water to the\nenthalpy excess can be crucial, how this contribution is affected by surface\ncharge remained to be understood. Here, we start by discussing how\nthermo-osmotic flows and induced electric currents are related to the\ninterfacial enthalpy excess. We then use molecular dynamics simulations to\ninvestigate the impact of surface charge on the interfacial enthalpy excess,\nfor different distributions of the surface charge, and two different wetting\nconditions. We observe that surface charge has a strong impact on enthalpy\nexcess, and that the dependence of enthalpy excess on surface charge depends\nlargely on its distribution. In contrast, wetting has a very small impact on\nthe charge-enthalpy coupling. We rationalize the results with simple analytical\nmodels, and explore their consequences for thermo-osmotic phenomena. Overall,\nthis work provides guidelines to search for systems providing optimal waste\nheat recovery performance.",
        "positive": "Nucleation in a sheared Ising model: effects of external field: Simulations using the Forward Flux Sampling method have shown a nonmonotonic\nde- pendence of the homogeneous nucleation rate on the shear rate for a sheared\ntwo dimensional Ising model [R. J. Allen et al, arXiv cond-mat/0805.3029]. For\nquasi-equilibrium systems (i.e. in the absence of shear), Classical Nucleation\nTheory (CNT) predicts the dependence of the critical cluster size and the\nnucleation rate on the external magnetic field. We investigate the behaviour of\nthe sheared Ising model as a function of the external field. At low exter- nal\nfield strength, the same nonmonotonic behaviour holds and the peak in the\nnucleation rate is remarkably insensitive to the field strength. This suggests\nthat the same external field-dependence holds for the enhancement of nucleation\nby shear at low shear rates and the suppression of shear at high shear rates.\nAt high field strength, the nucleation behaviour is qualitatively different. We\nalso analyse the size and shape of the largest cluster in the transition state\nconfigurations, as a function of the external field. In the sheared system, the\ntransition state cluster becomes larger and more elongated as the field\nstrength decreases. We compare our results for the sheared system to the\npredictions of the CNT for the quasi- equilibrium case, and find that the CNT\ncannot easily be used to describe nucleation in the system under shear."
    },
    {
        "anchor": "Magnetic control of the interaction in ultracold K-Rb mixtures: We predict the presence of several magnetic Feshbach resonances in selected\nZeeman sublevels of the isotopic pairs K(40)-Rb(87) and K(41)-Rb(87) at\nmagnetic fields up to 1000 G. Positions and widths are determined combining a\nnew measurement of the K(40)-Rb(87) inelastic cross section with recent\nexperimental results on both isotopes. The possibility of driving a K-Rb\nmixtures from the weak to the strong interacting regime tuning the applied\nfield should allow to achieve the optimal conditions for boson-induced Cooper\npairing in a multi component K(40)-Rb(87) atomic gas and for the production of\nultracold polar molecules.",
        "positive": "Preaveraging description of polymer nonequilibrium stretching: This article focuses on a preaveraging description of polymer nonequilibrium\nstretching, where a single polymer undergoes a transient process from\nequilibrium to nonequilibrium steady state by pulling one chain end. The\npreaveraging method combined with mode analysis reduces the original Langevin\nequation to a simplified form for both a stretched steady state and an\nequilibrium state, even in the presence of self-avoiding repulsive interactions\nspanning a long range. However, the transient stretching process exhibits\nevolution of a hierarchal regime structure, which means a qualitative temporal\nchange in probabilistic distributions assumed in preaveraging. We investigate\nthe preaveraging method for evolution of the regime structure with\nconsideration of the nonequilibrium work relations and deviations from the\nfluctuation-dissipation relation."
    },
    {
        "anchor": "Ergodic-nonergodic transition in tapped granular systems: The role of\n  persistent contacts: Static granular packs have been studied in the last three decades in the\nframe of a modified equilibrium statistical mechanics that assumes ergodicity\nas a basic postulate. The canonical example on which this framework is tested\nconsists in the series of static configurations visited by a granular column\nsubjected to taps. By analyzing the response of a realistic model of grains, we\ndemonstrate that volume and stress variables visit different regions of the\nphase space at low tap intensities in different realizations of the experiment.\nWe show that the tap intensity beyond which sampling by tapping becomes ergodic\ncoincides with the forcing necessary to break all particle-particle contacts\nduring each tap. These results imply that the well-known \"reversible\" branch of\ntapped granular columns is only valid at relatively high tap intensities.",
        "positive": "Elasticity and mechanical instability of charged lipid bilayers in ionic\n  solutions: We use coarse-grained Monte Carlo simulations to study the elastic properties\nof charged membranes in solutions of monovalent and pentavalent counterions.\nThe simulation results of the two cases reveal trends opposite to each other.\nThe bending rigidity and projected area increase with the membrane charge\ndensity for monovalent counterions, while they decrease for the pentavalent\nions. These observations can be related to the counterion screening of the\nlipid charges. While the monovalent counterions only weakly screen the Coulomb\ninteractions, which implies a repulsive Coulomb system, the multivalent\ncounterions condense on the membrane and, through spatial charge correlations,\nmake the effective interactions due the charged lipids attractive. The\ndifferences in the elastic properties of the charged membranes in monovalent\nand multivalent counterion solutions are reflected in the mechanisms leading to\ntheir mechanical instability at high charge densities. In the former case, the\nmembranes develop pores to relieve the electrostatic tensile stresses, while in\nthe latter case, the membrane exhibit large wavelength bending instability."
    },
    {
        "anchor": "A constraint-based approach to granular dispersion rheology: We present a phenomenological model for granular suspension rheology in which\nparticle interactions enter as constraints to relative particle motion. By\nconsidering constraints that are formed and released by stress respectively, we\nderive a range of experimental flow curves in a single treatment and predict\nsingularities in viscosity and yield stress consistent with literature data.\nFundamentally, we offer a generic description of suspension flow that is\nindependent of bespoke microphysics.",
        "positive": "Extreme heterogeneity in the microrheology of lamellar surfactant gels\n  analyzed with neural networks: The heterogeneity of the viscoelasticity of a lamellar gel network based on\ncetyl-trimethylammonium chloride (CTAC) and ceto-stearyl alcohol was studied\nusing particle tracking microrheology. A recurrent neural network (RNN)\narchitecture was used for estimating the Hurst exponent, $H$, on small sections\nof tracks of probe spheres moving with fractional Brownian motion. Thus dynamic\nsegmentation of tracks via neural networks was used in microrheology for the\nfirst time and it is significantly more accurate than using mean square\ndisplacements. An ensemble of 414 particles produces a mean squared\ndisplacement (MSD) that is subdiffusive in time, $t$, with a power law of the\nform $t^{0.74\\pm0.02}$, indicating power law viscoelasticity. RNN analysis of\nthe probability distributions of $H$, combined with detailed analysis of the\ntime-averaged MSDs of individual tracks, revealed diverse diffusion processes\nbelied by the simple scaling of the ensemble MSD, such as caging phenomena,\nwhich give rise to the complex viscoelasticity of lamellar gels."
    },
    {
        "anchor": "Detachment of fluid membrane from substrate and vesiculation: The detachment dynamics of a fluid membrane with an isotropic spontaneous\ncurvature from a flat substrate are studied by using meshless membrane\nsimulations. The membrane is detached from an open edge leading to vesicle\nformation. With strong adhesion, the competition between the bending and\nadhesion energies determines the minimum value of the spontaneous curvature for\nthe detachment. In contrast, with weak adhesion, a detachment occurs at smaller\nspontaneous curvatures due to the membrane thermal undulation. When parts of\nthe membrane are pinned on the substrate, the detachment becomes slower and a\nremained membrane patch forms straight or concave membrane edges. The edge\nundulation induces vesiculation of long strips and disk-shaped patches.\nTherefore, membrane rolling is obtained only for membrane strips shorter than\nthe wavelength for deformation into unduloid. This suggests that the rolling\nobserved for Ca$^{2+}$-dependent membrane-binding proteins, annexins A3, A4,\nA5, and A13, results from by the anisotropic spontaneous curvature induced by\nthe proteins.",
        "positive": "Theoretical model of membrane protrusions driven by curved active\n  proteins: Eukaryotic cells intrinsically change their shape, by changing the\ncomposition of their membrane and by restructuring their underlying\ncytoskeleton. We present here further studies and extensions of a minimal\nphysical model, describing a closed vesicle with mobile curved membrane protein\ncomplexes. The cytoskeletal forces describe the protrusive force due to actin\npolymerization which is recruited to the membrane by the curved protein\ncomplexes. We characterize the phase diagrams of this model, as function of the\nmagnitude of the active forces, nearest-neighbor protein interactions and the\nproteins' spontaneous curvature. It was previously shown that this model can\nexplain the formation of lamellipodia-like flat protrusions, and here we\nexplore the regimes where the model can also give rise to filopodia-like\ntubular protrusions. We extend the simulation with curved components of both\nconvex and concave species, where we find the formation of complex ruffled\nclusters, as well as internalized invaginations that resemble the process of\nendocytosis and macropinocytosis. We alter the force model representing the\ncytoskeleton to simulate the effects of bundled instead of branched structure,\nresulting in shapes which resemble filopodia."
    },
    {
        "anchor": "Monte Carlo Simulation of a Model of Water: We simulate TIP3P water using a constrained Monte Carlo algorithm to generate\nelectrostatic interactions eliminating the need to sum over long ranged Coulomb\ninteractions. We study discretization errors when interpolating charges using\nsplines and Gaussians. We compare our implementation to molecular dynamics and\nBrownian dynamics codes.",
        "positive": "Dynamics of flexible fibers in shear flow: Dynamics of flexible non-Brownian fibers in shear flow at low-Reynolds-number\nare analyzed numerically for a wide range of the ratios A of the fiber bending\nforce to the viscous drag force. Initially, the fibers are aligned with the\nflow, and later they move in the plane perpendicular to the flow vorticity. A\nsurprisingly rich spectrum of different modes is observed when the value of A\nis systematically changed, with sharp transitions between coiled and\nstraightening out modes, period-doubling bifurcations from periodic to\nmigrating solutions, irregular dynamics and chaos."
    },
    {
        "anchor": "Single Molecule Statistics and the Polynucleotide Unzipping Transition: We present an extensive theoretical investigation of the mechanical unzipping\nof double-stranded DNA under the influence of an applied force. In the limit of\nlong polymers, there is a thermodynamic unzipping transition at a critical\nforce value of order 10 pN, with different critical behavior for homopolymers\nand for random heteropolymers. We extend results on the disorder-averaged\nbehavior of DNA's with random sequences to the more experimentally accessible\nproblem of unzipping a single DNA molecule. As the applied force approaches the\ncritical value, the double-stranded DNA unravels in a series of discrete,\nsequence-dependent steps that allow it to reach successively deeper energy\nminima. Plots of extension versus force thus take the striking form of a series\nof plateaus separated by sharp jumps. Similar qualitative features should\nreappear in micromanipulation experiments on proteins and on folded RNA\nmolecules. Despite their unusual form, the extension versus force curves for\nsingle molecules still reveal remnants of the disorder-averaged critical\nbehavior. Above the transition, the dynamics of the unzipping fork is related\nto that of a particle diffusing in a random force field; anomalous,\ndisorder-dominated behavior is expected until the applied force exceeds the\ncritical value for unzipping by roughly 5 pN.",
        "positive": "Induced Charge-Density Oscillations at Metal Surfaces: Induced charge-density (ICD) oscillations at the Cu(111) surface caused by an\nexternal impurity are studied within linear response theory. The calculation\ntakes into account such properties of the Cu(111) surface electronic structure\nas an energy gap for three-dimensional (3D) bulk electrons and a $s-p_z$\nsurface state that forms two-dimensional (2D) electron system. It is\ndemonstrated that the coexistence of these 2D and 3D electron systems has\nprofound impact on the ICD in the surface region. In the case of a static\nimpurity the characteristic ICD oscillations with the $1/\\rho^2$ decay as a\nfunction of lateral distance, $\\rho$, are established in both electron systems.\nFor the impurity with a periodically time-varying potential, the novel dominant\nICD oscillations which fall off like $\\sim1/\\rho$ are predicted."
    },
    {
        "anchor": "Effect of polydispersity on the dynamics of active Brownian particles: We numerically study the dynamics and the phases of self-propelled\ndisk-shaped particles of different sizes with soft repulsive potential in two\ndimensions. Size diversity is introduced by the polydispersity index (PDI)\n$\\epsilon$, which is the width of the uniform distribution of the particle's\nradius. The self-propulsion speed of the particles controls the activity $v$.\nWe observe enhanced dynamics for large size diversity among the particles. We\ncalculate the effective diffusion coefficient $D_{eff}$ in the steady-state.\nThe system exhibits four distinct phases, jammed phase with small $D_{eff}$ for\nsmall activity and liquid phase with enhanced $D_{eff}$ for large activity. The\nnumber fluctuation is larger and smaller than the equilibrium limit in the\nliquid and jammed phase, respectively. Further, the jammed phase is of two\ntypes: solid-jammed and liquid jammed for small and large PDI. Whereas the\nliquid phase is called motility induced phase separation (MIPS)-liquid for\nsmall PDI and for large PDI, we find enhanced diffusivity and call it the {\\em\npure liquid} phase. The system is studied for three packing densities $\\phi$,\nand the response of the system for polydispersity is the same for all $\\phi$'s.\nOur study can help understand the behavior of cells of various sizes in a\ntissue, artificial self-driven granular particles, or living organisms of\ndifferent sizes in a dense environment.",
        "positive": "Confinement Effects on the Kinetics and Thermodynamics of Protein\n  Dimerization: In the cell, protein complexes form relying on specific interactions between\ntheir monomers. Excluded volume effects due to molecular crowding would lead to\ncorrelations between molecules even without specific interactions. What is the\ninterplay of these effects in the crowded cellular environment? We study\ndimerization of a model homodimer both when the mondimers are free or tethered\nto each other. We consider a structured environment: Two monomers first diffuse\ninto a cavity of size $L$ and then fold and bind within the cavity. The folding\nand binding are simulated using molecular dynamics based on a simplified\ntopology based model. The {\\it confinement} in the cell is described by an\neffective molecular concentration $C \\sim L^{-3}$. A two-state coupled folding\nand binding behavior is found. We show the maximal rate of dimerization\noccurred at an effective molecular concentration $C^{op}\\simeq 1m$M which is a\nrelevant cellular concentration. In contrast, for tethered chains the rate\nkeeps at a plateau when $C<C^{op}$ but then decreases sharply when $C>C^{op}$.\nFor both the free and tethered cases, the simulated variation of the rate of\ndimerization and thermodynamic stability with effective molecular concentration\nagrees well with experimental observations. In addition, a theoretical argument\nfor the effects of confinement on dimerization is also made."
    },
    {
        "anchor": "Distinct stick-slip modes in adhesive polymer interfaces: Stick-slip, manifest as intermittent tangential motion between two solids, is\na well-known friction instability that occurs in a number of natural and\nengineering systems. In the context of adhesive polymer interfaces, this\nphenomenon has often been solely associated with Schallamach waves, which are\ntermed slow waves due to their low propagation speeds. We study the dynamics of\na model polymer interface using coupled force measurements and high speed\n\\emph{in situ} imaging, to explore the occurrence of stick-slip linked to other\nslow wave phenomena. Two new waves---slip pulse and separation pulse---both\ndistinct from Schallamach waves, are described. The slip pulse is a sharp\nstress front that propagates in the same direction as the Schallamach wave,\nwhile the separation pulse involves local interface detachment and travels in\nthe opposite direction. Transitions between these stick-slip modes are easily\neffected by changing the sliding velocity or normal load. The properties of\nthese three waves, and their relation to stick-slip is elucidated. We also\ndemonstrate the important role of adhesion in effecting wave propagation.",
        "positive": "Beyond freezing: amorphous water in biomimetic soft nanoconfinement: Water is a ubiquitous liquid with unique physico-chemical properties, whose\nnature has shaped our planet and life as we know it. Water in restricted\ngeometries has different properties than in bulk. Confinement can prevent\nlow-temperature crystallization into a hexagonal structure, thus creating a\nstate of amorphous water. In this work we introduce a family of synthetic\nlipids with designed cyclopropyl modification in the hydrophobic chains that\nexhibit unique liquid-crystalline behaviour at low temperature, enabling\nmaintenance of amorphous water down to 10 K due to nanoconfinement in a\nbio-mimetic milieu. Small and Wide Angle X-ray Scattering, Elastic and\nInelastic Neutron Scattering, Nuclear Magnetic Resonance Spectroscopy and\nDifferential Scanning Calorimetry, complemented by Molecular Dynamics\nSimulations, unveil a complex lipid/water phase diagram, in which bicontinuous\ncubic and lamellar liquid crystalline phases containing sub-zero liquid,\nglassy, or ice water emerge as a competition between the two components, each\npushing towards its thermodynamically favoured state."
    },
    {
        "anchor": "Designing metachronal waves of cilia: On surfaces with many motile cilia, beats of the individual cilia coordinate\nto form metachronal waves. We present a theoretical framework that connects the\ndynamics of an individual cilium to the collective dynamics of a ciliary carpet\nvia systematic coarse-graining. We uncover the criteria that control the\nselection of frequency and wavevector of stable metchacronal waves of the cilia\nand examine how they depend on the geometric and dynamical characteristics of\nsingle cilia, as well as the geometric properties of the array. We perform\nagent-based numerical simulations of arrays of cilia with hydrodynamic\ninteractions and find quantitative agreement with the predictions of the\nanalytical framework. Our work sheds light on the question of how the\ncollective properties of beating cilia can be determined using information\nabout the individual units, and as such exemplifies a bottom-up study of a rich\nactive matter system.",
        "positive": "Quantifying the performances of SU-8 microfluidic devices: high liquid\n  water tightness, long-term stability, and vacuum compatibility: Despite several decades of development, microfluidics lacks a sealing\nmaterial that can be readily fabricated, leak-tight under high liquid water\npressure, stable over a long time, and vacuum compatible. In this paper, we\nreport the performances of a micro-scale processable sealing material for\nnanofluidic/microfluidics chip fabrication, which enables us to achieve all\nthese requirements. We observed that micrometric walls made of SU-8\nphotoresist, whose thickness can be as low as 35 $\\mu$m, exhibit water pressure\nleak-tightness from 1.5 bar up to 5.5 bar, no water porosity even after 2\nmonths of aging, and are able to sustain under $10^{-5}$ mbar vacuum. This\nsealing material is therefore reliable and versatile for building microchips,\npart of which must be isolated from liquid water under pressure or vacuum.\nMoreover, the fabrication process we propose does not require the use of\naggressive chemicals or high-temperature or high-energy plasma treatment. It\nthus opens a new perspective to seal microchips where delicate surfaces such as\nnanomaterials are present."
    },
    {
        "anchor": "Macroscopic emulation of microscopic magnetic particle systems: In this work we show that macroscopic experiments can be used to investigate\nmicroscopic systems. Such macroscopic experiments enable testing the\nassumptions and results obtained by theoretical considerations or simulations\nthat can not be obtained under microscope (e.g., the orientation of a spherical\nparticle). To emulate the dynamics of a single hematite cube immersed in water\nand subjected to a rotating magnetic field, a cubic magnet is firmly positioned\nin a 3D printed superball shell. The dimensionless parameters of the\nmicroscopic and macroscopic systems can be equalized by using a glycerol-water\nmixture instead of water as well as by the material and infill of the 3D\nprinted shell. The pose of the superball is tracked using ArUco stickers which\nact as fiducial markers. It was found that there is a qualitative agreement\nbetween the macroscopic experiments and theoretical predictions. However, the\nreduced thermal effects in the macroscopic experiments lead to an increase in\nfriction between the superball and the surface, thus shifting the critical\nfrequency of the system. Since the shell is 3D printed, the given method can be\nextended to any shape and magnetization orientation.",
        "positive": "A Simple and Effective Solution to the Constrained QM/MM Simulations: It is a promising extension of the quantum mechanical/molecular mechanical\n(QM/MM) approach to incorporate the solvent molecules surrounding the QM solute\ninto the QM region to ensure the adequate description of the electronic\npolarization of the solute. However, the solvent molecules in the QM region\ninevitably diffuse into the MM bulk during the QM/MM simulation. In this\narticle we developed a simple and efficient method, referred to as boundary\nconstraint with correction (BCC), to prevent the diffusion of the solvent water\nmolecules by means of a constraint po- tential. The point of the BCC method is\nto compensate the error in a statistical property due to the bias potential by\nadding a correction term obtained through a set of QM/MM simulations. The BCC\nmethod is designed so that the effect of the bias potential completely vanishes\nwhen the QM solvent is identical with the MM solvent. Furthermore, the\ndesirable conditions, that is, the continuities of energy and force and the\nconservations of energy and momentum, are fulfilled in principle. We applied\nthe QM/MM-BCC method to a hydronium ion in aqueous solution to construct the\nradial distribution function(RDF) of the solvent around the solute. It was\ndemonstrated that the correction term fairly compensated the error and led the\nRDF in good agreement with the result given by an ab initio molecular dynamics\nsimulation."
    },
    {
        "anchor": "Three Body Fluctuation-Induced Interaction at Fluid Interfaces: A Strong\n  Deviation from the Pairwise Summation: We present a new method based on the scattering technique to investigate\nfluctuation-induced forces at a fluid interface. The scattering approach, well\nsuited to the study of many body systems of arbitrary geometries, is augmented\nto include boundary fluctuations. Using this method, we study the deviation of\nthe total fluctuation-induced interaction from the sum of pairwise energies for\nthree colloidal particles. We consider both frozen and fluctuating colloids and\nobtain a very good agreement between analytical and numerical results. We find\na marked difference in the three body fluctuation-induced free energy between\nthe frozen and fluctuating colloids, both in sign and relative size.",
        "positive": "Response evolution of mechanical metamaterials under architectural\n  transformations: Architectural transformations play a key role in the evolution of complex\nsystems, from design algorithms for metamaterials to flow and plasticity of\ndisordered media. Here, we develop a general framework for the evolution of the\nlinear mechanical response of network structures under discrete architectural\ntransformations via sequential removal and addition of elastic elements. We\nfocus on a class of spatially complex metamaterials, consisting of triangular\nbuilding blocks. Rotations of these building blocks, corresponding to removing\nand adding elastic elements, introduce (topological) architectural defects. We\nshow that the metamaterials' states of self stress play a crucial role, and\nthat the mutually exclusive self stress states between two different network\narchitectures span the difference in their mechanical response. For our class\nof metamaterials, we identify a localized representation of these states of\nself stress, which allows us to capture the evolving response. We use our\ninsights to understand the unusual stress-steering behaviour of topological\ndefects."
    },
    {
        "anchor": "Ludwig: A parallel Lattice-Boltzmann code for complex fluids: This paper describes `Ludwig', a versatile code for the simulation of\nLattice-Boltzmann (LB) models in 3-D on cubic lattices. In fact `Ludwig' is not\na single code, but a set of codes that share certain common routines, such as\nI/O and communications. If `Ludwig' is used as intended, a variety of complex\nfluid models with different equilibrium free energies are simple to code, so\nthat the user may concentrate on the physics of the problem, rather than on\nparallel computing issues. Thus far, `Ludwig''s main application has been to\nsymmetric binary fluid mixtures. We first explain the philosophy and structure\nof `Ludwig' which is argued to be a very effective way of developing large\ncodes for academic consortia. Next we elaborate on some parallel implementation\nissues such as parallel I/O, and the use of MPI to achieve full portability and\ngood efficiency on both MPP and SMP systems. Finally, we describe how to\nimplement generic solid boundaries, and look in detail at the particular case\nof a symmetric binary fluid mixture near a solid wall. We present a novel\nscheme for the thermodynamically consistent simulation of wetting phenomena, in\nthe presence of static and moving solid boundaries, and check its performance.",
        "positive": "Magnetic Field Dependence of Macroscopic Quantum Tunneling and Coherence\n  of Ferromagnetic Particle: We calculate the quantum tunneling rate of a ferromagnetic particle of $\\sim\n100 \\AA$ diameter in a magnetic field of arbitrary angle. We consider the\nmagnetocrystalline anisotropy with the biaxial symmetry and that with the\ntetragonal symmetry. Using the spin-coherent-state path integral, we obtain\napproximate analytic formulas of the tunneling rates in the small $\\epsilon\n(=1- H/H_c)$-limit for the magnetic field normal to the easy axis ($\\theta_H =\n\\pi/2$), for the field opposite to the initial easy axis ($\\theta_H = \\pi$),\nand for the field at an angle between these two orientations ($\\pi/2 <<\n\\theta_H << \\pi$). In addition, we obtain numerically the tunneling rates for\nthe biaxial symmetry in the full range of the angle $\\theta_H$ of the magnetic\nfield ($\\pi/2 < \\theta_H \\leq \\pi$), for the values of \\epsilon =0.01 and\n0.001."
    },
    {
        "anchor": "Minimalistic Hybrid Models for the Adsorption of Polymers and Peptides\n  to Solid Substrates: We have performed chain-growth simulations of minimalistic hybrid lattice\nmodels for polymers interacting with interfaces of attractive solid substrates\nin order to gain insights into the conformational transitions of the polymers\nin the adsorption process. Primarily focusing on the dependence of the\nconformational behavior on temperature and solubility we obtained pseudophase\ndiagrams with a detailed structure of conformational subphases. In the study of\nhydrophobic-polar peptides in the vicinity of different types of substrates, we\nfound a noticeable substrate specificity of the assembly of hydrophobic domains\nin the conformations dominating the adsorption subphases.",
        "positive": "Effect of Ordering on Spinodal Decomposition of Liquid-Crystal/Polymer\n  Mixtures: Partially phase-separated liquid-crystal/polymer dispersions display highly\nfibrillar domain morphologies that are dramatically different from the typical\nstructures found in isotropic mixtures. To explain this, we numerically explore\nthe coupling between phase ordering and phase separation kinetics in model\ntwo-dimensional fluid mixtures phase separating into a nematic phase, rich in\nliquid crystal, coexisting with an isotropic phase, rich in polymer. We find\nthat phase ordering can lead to fibrillar networks of the minority polymer-rich\nphase."
    },
    {
        "anchor": "Mesoscopic Turbulence and Local Order in Janus Particles Self-Propelling\n  under an AC Electric Field: To elucidate mechanisms of mesoscopic turbulence exhibited by active\nparticles, we experimentally study turbulent states of non-living\nself-propelled particles. We realize an experimental system with dense\nsuspensions of asymmetrical colloidal particles (Janus particles)\nself-propelling on a two-dimensional surface under an AC electric field.\nVelocity fields of the Janus particles in the crowded situation can be regarded\nas a sort of turbulence because it contains many vortices and their velocities\nchange abruptly. Correlation functions of their velocity field reveal the\ncoexistence of polar alignment and anti-parallel alignment interactions, which\nis considered to trigger mesoscopic turbulence. Probability distributions of\nlocal order parameters for polar and nematic orders indicate the formation of\nlocal clusters with particles moving in the same direction. A broad peak in the\nenergy spectrum of the velocity field appears at the spatial scales where the\npolar alignment and the cluster formation are observed. Energy is injected at\nthe particle scale and such conserved quantity as energy could be cascading\ntoward the larger clusters.",
        "positive": "Unravelling the Mechanics of Knitted Fabrics Through Hierarchical\n  Geometric Representation: Knitting interloops one-dimensional yarns into three-dimensional fabrics that\nexhibit behaviours beyond their constitutive materials. How extensibility and\nanisotropy emerge from the hierarchical organisation of yarns into knitted\nfabrics has long been unresolved. We sought to unravel the mechanical roles of\ntensile mechanics, assembly and dynamics arising from the yarn level on fabric\nnonlinearity by developing a yarn-based dynamical model. This physically\nvalidated model captures the fundamental mechanical response of knitted\nfabrics, analogous to flexible metamaterials and biological fiber networks due\nto geometric nonlinearity within such hierarchical systems. Fabric anisotropy\noriginates from observed yarn-yarn rearrangements during alignment dynamics and\nis topology-dependent. This yarn-based model also provides a design space of\nknitted fabrics to embed functionalities by varying geometric configuration and\nmaterial property in instructed procedures compatible to machine manufacturing.\nOur hierarchical approach to build up a knitted fabrics computationally\nmodernizes an ancient craft and represents a first step towards mechanical\nprogrammability of knitted fabrics in wide engineering applications."
    },
    {
        "anchor": "A first-order phase transition at the random close packing of hard\n  spheres: Randomly packing spheres of equal size into a container consistently results\nin a static configuration with a density of ~64%. The ubiquity of random close\npacking (RCP) rather than the optimal crystalline array at 74% begs the\nquestion of the physical law behind this empirically deduced state. Indeed,\nthere is no signature of any macroscopic quantity with a discontinuity\nassociated with the observed packing limit. Here we show that RCP can be\ninterpreted as a manifestation of a thermodynamic singularity, which defines it\nas the \"freezing point\" in a first-order phase transition between ordered and\ndisordered packing phases. Despite the athermal nature of granular matter, we\nshow the thermodynamic character of the transition in that it is accompanied by\nsharp discontinuities in volume and entropy. This occurs at a critical\ncompactivity, which is the intensive variable that plays the role of\ntemperature in granular matter. Our results predict the experimental conditions\nnecessary for the formation of a jammed crystal by calculating an analogue of\nthe \"entropy of fusion\". This approach is useful since it maps\nout-of-equilibrium problems in complex systems onto simpler established\nframeworks in statistical mechanics.",
        "positive": "Drying of a Microdroplet of Water Suspension of Nanoparticles: from\n  Surface Aggregates to Microcrystal: The method of formation of nanoparticle aggregates such as high-coverage\nspherical shells of microspheres or 3-D micro crystals grown in the geometry\nunaffected by a substrate is described. In the reported experiment, the\nevaporation of single levitated water droplet containing 200 nm diameter\npolystyrene spheres was studied. Successive stages of the drying process were\ndiscussed by analyzing the intensity of light elastically scattered by the\nevaporating droplet. The numerically simulated self-assembly coincides nicely\nwith the observed morphologies resulting from transformation of a droplet of\nsuspension into a solid microcrystal via kinetically driven self-assembly of\nnanostructures."
    },
    {
        "anchor": "Atomic Transport in Dense, Multi-Component Metallic Liquids: Pd43Ni10Cu27P0 has been investigated in its equilibrium liquid state with\nincoherent, inelastic neutron scattering. As compared to simple liquids, liquid\nPdNiCuP is characterized by a dense packing with a packing fraction above 0.5.\nThe intermediate scattering function exhibits a fast relaxation process that\nprecedes structural relaxation. Structural relaxation obeys a time-temperature\nsuperposition that extends over a temperature range of 540K. The mode-coupling\ntheory of the liquid to glass transition (MCT) gives a consistent description\nof the dynamics which governs the mass transport in liquid PdNiCuP alloys. MCT\nscaling laws extrapolate to a critical temperature Tc at about 20% below the\nliquidus temperature. Diffusivities derived from the mean relaxation times\ncompare well with Co diffusivities from recent tracer diffusion measurements\nand diffsuivities calculated from viscosity via the Stokes-Einstein relation.\nIn contrast to simple metallic liquids, the atomic transport in dense, liquid\nPdNiCuP is characterized by a drastical slowing down of dynamics on cooling, a\nq^{-2} dependence of the mean relaxation times at intermediate q and a\nvanishing isotope effect as a result of a highly collective transport\nmechanism. At temperatures as high as 2Tc diffusion in liquid PdNiCuP is as\nfast as in simple liquids at the melting point. However, the difference in the\nunderlying atomic transport mechanism indicates that the diffusion mechanism in\nliquids is not controlled by the value of the diffusivity but rather by that of\nthe packing fraction.",
        "positive": "Continuum Theory of Tkachenko Modes in Rotating Bose-Einstein Condensate: The present paper suggests the continuum theory of Tkachenko modes in a\nrotating 2D Bose-Einstein condensate taking into account density inhomogeneity\nand compressibility of the condensate. The problem requires solution of coupled\nhydrodynamic equations for vortex and liquid motion with proper boundary\nconditions, which were derived for the condensate described by the Thomas-Fermi\napproximation. Compressibility becomes essential at rapid rotation with angular\nvelocity close to the trap frequency. The theory is in a reasonable agreement\nwith experimental observation of Tkachenko modes."
    },
    {
        "anchor": "Hydrophobicity and Unique Folding of Selected Polymers: In suitable environments, proteins, nucleic acids and certain synthetic\npolymers fold into unique conformations. This work shows that it is possible to\nconstruct lattice models of foldable heteropolymers by expressing the energy\nonly in terms of individual properties of monomers, such as the exposure to the\nsolvent and the steric factor.",
        "positive": "Simulating Copolymeric Nanoparticle Assembly in the Co-solvent Method:\n  How Mixing Rates Control Final Particle Sizes and Morphologies: The self-assembly of copolymeric vesicles and micelles in micromixers is\nstudied by External Potential Dynamics (EPD) simulations -- a dynamic density\nfunctional approach that explicitly accounts for the polymer architecture both\nat the level of thermodynamics and dynamics. Specifically, we focus on the\nco-solvent method, where nanoparticle precipitation is triggered by mixing a\npoor co-solvent into a homogeneous copolymer solution in a micromixer.\nExperimentally, it has been reported that the flow rate in the micromixers\ninfluences the size of the resulting particles as well as their morphology: At\nsmall flow rates, vesicles dominate; with increasing flow rate, more and more\nmicelles form, and the size of the particles decreases. Our simulation model is\nbased on the assumption that the flow rate mainly sets the rate of mixing of\nsolvent and co-solvent. The simulations reproduce the experimental observations\nat an almost quantitative level and provide insight into the underlying\nphysical mechanisms: First, they confirm an earlier conjecture according to\nwhich the size control takes place in the earliest stage of the particle\nself-assembly, during the spinodal decomposition of polymers and solvent.\nSecond, they reveal a crossover between different morphological regimes as a\nfunction of mixing rate. Hence they demonstrate that varying the mixing rate in\na co-solvent setup is an effective way to control two key properties of drug\ndelivery systems, their mean size and their morphology."
    },
    {
        "anchor": "Modeling Market Mechanism with Evolutionary Games: This is an essay solicited by Europhysics News, published in its March/April\n1998 issue with slight modifications. We outline some highlights of the\neconophysics models, especially the so-called Minority model of competition and\nevolution. Even without the usual math, this essay offers an analytical\nsolution to the Minority model, revealing some key features of the solution.",
        "positive": "Record Dynamics: Direct Experimental Evidence from Jammed Colloids: In a broad class of complex materials a quench leads to a multi-scaled\nrelaxation process known as aging. To explain its commonality and the\nastounding insensitivity to most microscopic details, record dynamics (RD)\nposits that a small set of increasingly rare and irreversible events, so called\nquakes, controls the dynamics. While key predictions of RD are known to concur\nwith a number of experimental and simulational results, its basic assumption on\nthe nature of quake statistics has proven extremely difficult to verify\nexperimentally. The careful distinction of rare (\"record\") cage-breaking events\nfrom in-cage rattle accomplished in previous experiments on jammed colloids,\nenables us to extract the first direct experimental evidence for the\nfundamental hypothesis of RD that the rate of quakes decelerates with the\ninverse of the system age. The resulting description shows the predicted growth\nof the particle mean square displacement and of a mesoscopic lengthscale with\nthe logarithm of time."
    },
    {
        "anchor": "Minimalist design of polymer-oligopeptide hybrid as intrinsically\n  disordered protein-mimicking scaffold for artificial membraneless organelle: Liquid-liquid phase separation (LLPS) is an emerging and universal mechanism\nfor intracellular biomolecule organization, particularly, via the formation of\nmembraneless organelles (MOs). Intrinsically disordered proteins (IDPs) are the\nmain constituents of MOs, wherein multivalent interactions and low-complexity\ndomains (LCDs) drive LLPS. Using short oligopeptide derived from LCDs as\n'stickers' and dextran backbones as 'spacers', we designed polymer-oligopeptide\nhybrids to mimic the multivalent FUS protein as represented by the\n'stickers-and-spacers' model. We demonstrated that hybrids underwent LLPS and\nself-assembled into micron-sized (mostly 1-10 micron, resembling LLPS in vitro\nand in living cells) compartments displaying liquid-like properties.\nFurthermore, the droplets formed were capable of recruiting proteins and RNAs,\nwhilst providing a favorable environment for enhanced biochemical reaction,\nthereby mimicking the function of natural MOs. We envision this simple yet\nversatile model system will help elucidate the molecular interactions\nimplicated in MO formation and pave ways to a new type of biomimetic materials.",
        "positive": "Characterizing Large Strain Elasticity of Brittle Elastomeric Networks\n  by Embedding Them in a Soft Extensible Matrix: Here, the general design and properties of new multiple network elastomers\nwith an exceptional combination of stiffness, toughness, and elasticity are\nreported. In this paper, it is reported in more detail how the increase in\nstrain at break resulting from the toughening can be used to provide great\ninsight in the large strain properties of otherwise brittle acrylic well\ncrosslinked networks. The networks have been prepared by sequences of\npolymerization and swelling with monomers. The parameters that have been varied\nare the nature of the base monomers and the degree of crosslinking of the first\nnetwork. Here, the small strain properties, equilibrium swelling, and large\nstrain properties in uniaxial tension are characterized. It is shown here that\nthe large strain properties of the multiple networks are quantitatively\ncontrolled by the large strain properties of the stretched first network which\nacts as a percolating filler, while the small and intermediate properties are\ncontrolled by the entanglement density which can be largely superior to that of\nhomogeneous networks. Different brittle and prestretched elastomer networks are\nembedded at a low volume fraction in a soft extensible matrix. The increase in\ntoughness of the final material is directly controlled by the nonlinear elastic\nproperties of the prestretched network and its volume fraction, providing a\ngeneral design rule for tough soft materials"
    },
    {
        "anchor": "Impact of granular inclusions on the phase behavior of colloidal gels: Colloidal gels formed from small attractive particles are commonly used in\nformulations to keep larger components in suspension. However, despite\nextensive work characterizing unfilled gels, little is known about how larger\ninclusions alter the phase behavior and microstructure of the colloidal system.\nHere we use numerical simulations to examine how larger `granular' particles\ncan alter the gel transition phase boundaries. We find two distinct regimes\ndepending on both the filler size and native gel structure: a `passive' regime\nwhere the filler fits into already-present voids, giving little change in the\ntransition, and an `active' regime where the filler no longer fits in these\nvoids and instead perturbs the native structure. In this second regime the\nphase boundary is controlled by an effective colloidal volume fraction given by\nthe available free volume.",
        "positive": "Emergence of preferred subnetwork for correlated transport in spatial\n  networks: On the ubiquity of force chains in dense disordered granular\n  materials: Stress in dense granular materials and other athermal particle aggregates is\ntransmitted through a visually striking subnetwork of interparticle contacts,\nthe filamentary segments of which are referred to as force chains. The\nemergence of such preferred subnetwork in structurally disordered media with\nconstituents interacting primarily by physical contact is not fully understood.\nIn this work, we study locally correlated transport in Random Geometric Graphs\n(RGGs), and show the spontaneous emergence of preferred subnetwork. Our\nfindings reveal that, despite structural disorder, system spanning localization\nof fluxes transmitted through a spatial network can emerge from short ranged\ncorrelations. The spatial and statistical features of the subnetwork are\nsurprisingly similar to the strong force network in simulated grain assemblies,\nand provides insights on the structure and spatial scale of significance of the\nforce chains."
    },
    {
        "anchor": "Non-spherical shapes of capsules within a fourth-order curvature model: We minimize a discrete version of the fourth-order curvature based Landau\nfree energy by extending Brakke's Surface Evolver. This model predicts\nspherical as well as non-spherical shapes with dimples, bumps and ridges to be\nthe energy minimizers. Our results suggest that the buckling and faceting\ntransitions, usually associated with crystalline matter, can also be an\nintrinsic property of non-crystalline membranes.",
        "positive": "Length scale dependent elasticity in DNA from coarse-grained and\n  all-atom models: The mechanical properties of DNA are typically described by elastic theories\nwith purely local couplings (on-site models). We discuss and analyze\ncoarse-grained (oxDNA) and all-atom simulations, which indicate that in DNA\ndistal sites are coupled. Hence, off-site models provide a more realistic\ndescription of the mechanics of the double helix. We show that off-site\ninteractions are responsible for a length scale dependence of the elasticity,\nand we develop an analytical framework to estimate bending and torsional\npersistence lengths in models including these interactions. Our simulations\nindicate that off-site couplings are particularly strong for certain degrees of\nfreedom, while they are very weak for others. If stiffness parameters obtained\nfrom DNA data are used, the theory predicts large length scale dependent\neffects for torsional fluctuations and a modest effect in bending fluctuations,\nwhich is in agreement with experiments."
    },
    {
        "anchor": "Reactive infiltration: identifying the role of chemical reactions,\n  capillarity, viscosity and gravity: A wealth of experimental data indicate that while capillarity controlled\ninfiltration gives an infiltration length that varies with the square root of\ntime, reactive infiltration is characterised by a linear relationship between\nthe two magnitudes. In addition the infiltration rate in the latter is at least\ntwo orders of magnitude greater than in the former.\n  This work is addressed to investigate imbibition of a non-wetting, albeit\nreactive, liquid into a capillary, within the framework of a simple model that\nincludes capillarity effects, viscosity and gravity. The capillary radius is\nallowed to vary, due to reaction, with both position and time, according to\neither an interface or a diffusion law. The model allows for capillary closure\nwhen reaction kinetics dominates imbibition. At short times, and depending on\nwhether infiltration is capillarity or gravity controlled, the infiltrated\nlength varies either as the square root or linearly with time. This suggest the\nfollowing track for reactive infiltration: i) In most cases, the contact angle\nis initially larger than $90^\\circ$, ii) after some time, reaction gradually\nreplaces the interface liquid/preform by the liquid/reaction product interface\nand, concomitantly, the contact angle gets closer to $90^\\circ$, iii) beyond\nthat time, gravity triggers infiltration (actually the contact angle does not\nneed to be smaller than $90^\\circ$ for the initiation of infiltration due to\nthe metallostatic pressure exerted by the liquid metal on top of the porous\npreform), iv) thereafter infiltration is controlled by viscosity and gravity,\nprovided that, due to reaction, the contact angle remains close to that at\nwhich infiltration was initiated.",
        "positive": "Colloidal Shape Effects in Evaporating Drops: We explore the influence of particle shape on the behavior of evaporating\ndrops. A first set of experiments discovered that particle shape modifies\nparticle deposition after drying. For sessile drops, spheres are deposited in a\nring-like stain, while ellipsoids are deposited uniformly. Experiments\nelucidate the kinetics of ellipsoids and spheres at the drop's edge. A second\nset of experiments examined evaporating drops confined between glass plates. In\nthis case, colloidal particles coat the ribbon-like air-water interface,\nforming colloidal monolayer membranes (CMMs). As particle anisotropy increases,\nCMM bending rigidity was found to increase, which in turn introduces a new\nmechanism that produces a uniform deposition of ellipsoids and a heterogeneous\ndeposition of spheres after drying. A final set of experiments investigates the\neffect of surfactants in evaporating drops. The radially outward flow that\npushes particles to the drop's edge also pushes surfactants to the drop's edge,\nwhich leads to a radially inward flow on the drop surface. The presence of\nradially outward flows in the bulk fluid and radially inward flows at the drop\nsurface creates a Marangoni eddy, among other effects, which also modifies\ndeposition after drying."
    },
    {
        "anchor": "Static properties of quasi-confined hard-sphere fluids: Confined fluids display complex behavior due to layering and local packing.\nHere, we disentangle these effects by confining a hard-sphere fluid to the\nsurface of a cylinder, such the circumference extends only over a few particle\ndiameters. We compare the static structure factor and the pressure measured in\ncomputer simulations to the Percus-Yevick closure in liquid state theory. A\nnon-monotonic evolution of the static-structure-factor peak and the pressure is\nobserved upon variation of the confining length, similar to a liquid confined\nbetween two plates. This indicates that the density profile and the particle\ncorrelations may not be intrinsically connected in real confined liquids.",
        "positive": "Rigidity of Melting DNA: The temperature dependence of DNA flexibility is studied in the presence of\nstretching and unzipping forces. Two classes of models are considered. In one\ncase the origin of elasticity is entropic due to the polymeric correlations,\nand in the other the double-stranded DNA is taken to have an intrinsic rigidity\nfor bending. In both cases single strands are completely flexible. The change\nin the elastic constant for the flexible case due to thermally generated\nbubbles is obtained exactly. For the case of intrinsic rigidity, the elastic\nconstant is found to be proportional to the square root of the bubble number\nfluctuation."
    },
    {
        "anchor": "Biofilm mechanics and patterns: From multicellular tissues to bacterial colonies, three dimensional cellular\nstructures arise through the interaction of cellular activities and mechanical\nforces. Simple bacterial communities provide model systems for analyzing such\ninteraction. Biofilms are bacterial aggregates attached to wet surfaces and\nencased in a self-produced polymeric matrix. Biofilms in flows form filamentary\nstructures that contrast with the wrinkled layers observed on air/solid\ninterfaces. We are able to reproduce both types of shapes through elastic rod\nand plate models that incorporate information from the biomass production and\ndifferentiations process, such as growth rates, growth tensors or inner\nstresses, as well as constraints imposed by the interaction with environment. A\nmore precise study of biofilm dynamics requires tackling water absorption from\nits surroundings and fluid transport within the biological system. This process\nalters the material properties of the biofilm and the overall stresses. We\nanalyze whether poroelastic approaches can provide a suitable combined\ndescription of fluid-like and solid-like biofilm behavior.",
        "positive": "Convective Instability of Magnetized Ferrofluids: Influence of\n  Magnetophoresis and Soret Effect: Convective instability in a ferrofluid layer heated from below or from above\nin the presence of a uniform vertical magnetic field is investigated\ntheoretically. Convection is caused by a magnetic mechanism based on the\ntemperature and concentration dependence of magnetization. An imposed\ntemperature gradient establishes (by the Soret effect) a concentration gradient\nof magnetic particles of which the ferrofluid is composed. Both these gradients\ncause a spatial variation in magnetization, which induces a gradient of\nmagnetic field intensity within the fluid layer. The field gradient induces in\nits turn an additional redistribution of magnetic grains due to\nmagnetophoresis. Resulting self-consistent magnetic force tries to mix the\nfluid. A linear stability analysis predicts oscillatory instability in a\ncertain region of the magnetic field strength and the fluid parameters. The\ninstability owes magneto- and thermophoresis its origin: were the particle\ndiffusion not operative, then only stationary instability would occur. A\ndiscovery of predicted convective oscillations is expected in ferrofluid layers\nabout 1 mm thick, where the buoyancy mechanism is negligible and the\ncharacteristic diffusion time is not too long."
    },
    {
        "anchor": "Corrugation of an unpaved road surface under vehicle weight: Road corrugation refers to the formation of periodic, transverse ripples on\nunpaved road surfaces. It forms spontaneously on an initially flat surface\nunder heavy traffic and can be considered to be a type of unstable growth\nphenomenon, possibly caused by the local volume contraction of the underlying\nsoil due to a moving vehicle's weight. In the present work, we demonstrate a\npossible mechanism for road corrugation using experimental data of soil\nconsolidation and numerical simulations. The results indicate that the vertical\noscillation of moving vehicles, which is excited by the initial irregularities\nof the surface, plays a key role in the development of corrugation.",
        "positive": "Packing Concave Molecules in Crystals and Amorphous Solids: On the\n  Connection between Shape and Local Structure: The structure of the densest crystal packings is determined for a variety of\nconcave shapes in 2D constructed by the overlap of two or three disks. The\nmaximum contact number per particle pair is defined and proposed as a useful\nmeans of categorizing particle shape. We demonstrate that the densest packed\ncrystal exhibits a maximum in the number of contacts per particle but does not\nnecessarily include particle pairs with the maximum contact number. In\ncontrast, amorphous structures, generated by energy minimization of high\ntemperature liquids, typically do include maximum contact pairs. The amorphous\nstructures exhibit a large number of contacts per particle corresponding to\nover-constrained structures. Possible consequences of this over-constraint are\ndiscussed."
    },
    {
        "anchor": "Thermomechanical Modeling of Microstructure Evolution Caused by\n  Strain-Induced Crystallization: The present contribution deals with the thermomechanical modeling of the\nstrain-induced crystallization in unfilled polymers. This phenomenon\nsignificantly influences mechanical and thermal properties of polymers and has\nto be taken into consideration when planning manufacturing processes as well as\napplications of the final product. In order to simultaneously capture both\nkinds of effects, the model proposed starts by introducing a triple\ndecomposition of the deformation gradient and furthermore uses thermodynamic\nframework for material modeling based on the Coleman--Noll procedure and\nminimum principle of the dissipation potential, which requires suitable\nassumptions for the Helmholtz free energy and the dissipation potential. The\nchosen setup yields evolution equations which are able to simulate the\nformation and the degradation of crystalline regions accompanied by the\ntemperature change during a cyclic tensile test. The boundary value problem\ncorresponding to the described process includes the balance of linear momentum\nand balance of energy and serves as a basis for the numerical implementation\nwithin an FEM code. The~paper closes with the numerical examples showing the\nmicrostructure evolution and temperature distribution for different material\nsamples.",
        "positive": "Ideal Glasses and Protein Network Dynamics: Quantitative topological analogies between the flexibilities of optimized\ninorganic glasses, small biological molecules, and proteins suggest that mean\nfield estimates of internal stress are useful in identifying mechanisms\nsupporting living materials and their enzymatic products. These analogies bode\nwell for emerging minimalist flexibility models of protein dynamics.\nApplication to trehalose, the optimal bioprotective material, leads to a\nremarkably simple mechanical model, closely parallel to mechanical effects\nobserved in sandwich-like proteins."
    },
    {
        "anchor": "A wrinkled cylindrical shell as a tunable locking material: A buckled sheet offers a reservoir of material that can be unfurled at a\nlater time. For sufficiently thin yet stiff materials, this geometric process\nhas a striking mechanical feature: when the slack runs out, the material locks\nto further extension. Here we establish a simple route to a tunable locking\nmaterial - a system with an interval where it is freely deformable under a\ngiven deformation mode, and where the endpoints of this interval can be changed\ncontinuously over a wide range. We demonstrate this type of mechanical response\nin a thin cylindrical shell subjected to axial twist and compression, and we\nrationalize our results with a simple geometric model.",
        "positive": "Machine learning for crystal identification and discovery: As computers get faster, researchers -- not hardware or algorithms -- become\nthe bottleneck in scientific discovery. Computational study of colloidal\nself-assembly is one area that is keenly affected: even after computers\ngenerate massive amounts of raw data, performing an exhaustive search to\ndetermine what (if any) ordered structures occur in a large parameter space of\nmany simulations can be excruciating. We demonstrate how machine learning can\nbe applied to discover interesting areas of parameter space in colloidal self\nassembly. We create numerical fingerprints -- inspired by bond orientational\norder diagrams -- of structures found in self-assembly studies and use these\ndescriptors to both find interesting regions in a phase diagram and identify\ncharacteristic local environments in simulations in an automated manner for\nsimple and complex crystal structures. Utilizing these methods allows analysis\nmethods to keep up with the data generation ability of modern high-throughput\ncomputing environments."
    },
    {
        "anchor": "Liquid-Crystal Smectic with Six-Layer Periodic Structure: Recently Wang et al. [Phys. Rev. Lett. 104, 027801 (2010)] discovered a new\npolar smectic phase with six-layer period (SmC*d6). In this manuscript, we\ndemonstrate that the theory [Phys. Rev. E 67, 041716 (2003)] based on the free\nenergy expansion with a two-component order parameter predicted the six-layer\nphase, describes its structure and the phase sequence observed in experiment\n[Phys. Rev. Lett. 104, 027801 (2010)].",
        "positive": "Simulation of dense non-Brownian suspensions with the lattice Boltzmann\n  method: Shear jammed and fragile states: Dense non-Brownian suspensions including both the hydrodynamic interactions\nand the frictional contacts between particles are numerically studied under\nsimple and oscillatory shears in terms of the lattice Boltzmann method. We\nsuccessfully reproduce the discontinuous shear thickening (DST) under a simple\nshear for bulk three-dimensional systems. For our simulation of an oscillatory\nshear in a quasi-two-dimensional system, we measure the mechanical response\nwhen we reduce the strain amplitude after the initial oscillations with a\nlarger strain amplitude. Here, we find the existence of the shear-jammed state\nunder this protocol in which the storage modulus $G^{\\prime}$ is only finite\nfor high initial strain amplitude $\\gamma_0^{I}$. We also find the existence of\nthe fragile state in which both fluid-like and solid-like responses can be\ndetected for an identical area fraction and an initial strain amplitude\n$\\gamma_0^{I}$ depending on the initial phase $\\Theta$ (or the asymmetricity of\nthe applied strain) of the oscillatory shear. We also observe the DST-like\nbehavior under the oscillatory shear in the fragile state. Moreover, we find\nthat the stress anisotropy becomes large in the fragile state. Finally, we\nconfirm that the stress formula based on the angular distribution of the\ncontact force recovers the contact contributions to the stress tensors for both\nsimple and oscillatory shears with large strains."
    },
    {
        "anchor": "An Elastic Quartic Twist Theory for Chromonic Liquid Crystals: Chromonic liquid crystals are lyotropic materials which are attracting\ngrowing interest for their adapatbility to living systems. To describe their\nelastic properties, the classical Oseen-Frank theory requires anomalously small\ntwist constants and (comparatively) large saddle-splay constants, so large as\nto violate one of Ericksen's inequalities, which guarantee that the Oseen-Frank\nstored-energy density is bounded below. While such a violation does not prevent\nthe existence and stability of equilibrium distortions in problems with fixed\ngeometric confinement, the study of free-boundary problems for droplets has\nrevealed a number of paradoxical consequences. Minimizing sequences driving the\ntotal energy to negative infinity have been constructed by employing ever\ngrowing needle-shaped tactoids incorporating a diverging twist [Phy. Rev. E\n106, 044703 (2022)]. To overcome these difficulties, we propose here a novel\nelastic theory that extends for chromonics the classical Oseen-Frank stored\nenergy by adding a quartic twist term. We show that the total energy of\ndroplets is bounded below in the quartic twist theory, so that the known\nparadoxes are ruled out. The quartic term introduces a phenomenological length\n$a$ in the theory; this affects the equilibrium of chromonics confined within\ncapillary tubes. Use of published experimental data allows us to estimate $a$.",
        "positive": "Charging of dielectric surfaces in contact with aqueous electrolyte --\n  the influence of CO$_2$: The charge state of dielectric surfaces in aqueous environments is of\nfundamental and technological importance. Here, we study the influence of\ndissolved molecular CO$_2$ on the charging of three, chemically different\nsurfaces (SiO$_2$, Polystyrene, Perfluorooctadecyltrichlorosilane). We\ndetermine their charge state from electrokinetic experiments. We compare an\nideal, CO$_2$-free reference system to a system equilibrated against ambient\nCO$_2$ conditions. In the reference system, the salt-dependence is weakened for\nSiO$_2$ and inverted for the organic surfaces. We show that screening and\npH-driven charge regulation alone cannot explain the observed effects. As\nadditional cause, we tentatively suggest dielectric regulation of surface\ncharges due to a diffusively adsorbed thin layer of molecular CO$_2$. The\nformation of such a dynamic layer even at the hydrophilic and partially ionized\nsilica surfaces is supported by a minimal theoretical model and results from\nmolecular simulations."
    },
    {
        "anchor": "Polarobreathers in soft potentials: We consider polarons in models of coupled electronic and vibrational degrees\nof freedom, in the presence of a soft nonlinear inter-particle potential (Morse\npotential). In particular, we focus on a a bound state of a polaron with a\nbreather, a so-called ``polarobreather''. We analyze the existence of this\nbranch based on frequency resonance conditions and illustrate its stability\nusing Floquet spectrum techniques. Multi-site solutions of this type are also\nobtained both in the stationary case (two-site polarons) and in the breathing\ncase (two-site polarobreathers). We also obtain a different branch of\nsolutions, namely a polaronic nanopteron.",
        "positive": "Effect of Block Asymmetry on the Crystallization of Double Crystalline\n  Diblock Copolymers: Monte Carlo simulation on the crystallization of double crystalline diblock\ncopolymer unravels an intrinsic relationship between block asymmetry and\ncrystallization behaviour. We model crystalline A-B diblock copolymer, wherein\nthe melting temperature of A-block is higher than that of the B-block. We\nexplore the composition dependent crystallization behaviour by varying the\nrelative block length with weak and strong segregation strength between the\nblocks. In weak segregation limit, we observe that with increasing the\ncomposition of B-block, its crystallization temperature increases accompanying\nwith higher crystallinity. In contrast, A-block crystallizes at a relatively\nlow temperature along with the formation of thicker and larger crystallites\nwith the increase in B-block composition. We attribute this non-intuitive\ncrystallization trend to the dilution effect imposed by B-block. When the\ncomposition of the B-block is high enough, it acts like a 'solvent' during the\ncrystallization of A-block. A-block segments are more mobile and hence less\nfacile to crystallize, resulting depression in crystallization temperature with\nthe formation of thicker crystals. At strong segregation limit, crystallization\nand morphological development are governed by the confinement effect, rather\nthan block asymmetry. Isothermal crystallization reveals that the\ncrystallization follows a homogeneous nucleation mechanism with the formation\nof two dimensional crystals. Two-step, compared to one-step isothermal\ncrystallization leads to the formation of thicker crystals of A-block due to\nthe dilution effect of the B-block."
    },
    {
        "anchor": "Forced flow of granular media: Breakdown of the Beverloo scaling: The Beverloo scaling for the gravity flow of granular materials through\norifices has two distinct universal features. On the one hand, the flow rate is\nindependent of the height of the granular column. On the other hand, less\nwell-known yet more striking, the flow rate is fairly insensitive to the\nmaterial properties of the grains (density, Young's modulus, friction\ncoefficient, etc.). We show that both universal features are lost if work is\ndone on the system at a high rate. In contrast to viscous fluids, the flow rate\nincreases during discharge if a constant pressure is applied to the free\nsurface of a granular column. Moreover, the flow rate becomes sensitive to the\nmaterial properties. Nevertheless, a new universal feature emerges: the\ndissipated power scaled by the mean pressure and the flow rate follows a master\ncurve for forced and unforced conditions and for all material properties\nstudied. We show that this feature can be explained if the granular flow in the\nsilo is assumed to be a quasistatic shear flow under the $\\mu(I)$-rheology.",
        "positive": "Beam combining using Orientational Stimulated Scattering in Liquid\n  Crystals: Possibility of beam combining and clean-up using Orientational Stimulated\nScattering in a Nematic Liquid Crystal is considered. We numerically study the\ndynamics of the process and find that back-conversion process tends to limit\nthe effective interaction strength. Instability of the steady state of\ncross-phase modulation is demonstrated, when both waves have the same\nfrequency. We show that high conversion efficiency can be achieved, and that\nthe shape and wave-front of the amplified output signal are robust with respect\nto amplitude and phase distortions of the input pump."
    },
    {
        "anchor": "Tuning light matter interaction in magnetic nanofluid based field\n  induced photonic crystal-glass structure by controlling optical path length: The ability to control the light matter interaction and simultaneous tuning\nof both structural order and disorder in materials, although are important in\nphotonics, but still remain as major challenges. In this paper, we show that\noptical path length dictates light-matter interaction in the same crystal\nstructure formed by the ordering of magnetic nanoparticle self-assembled\ncolumns inside magnetic nanofluid under applied field. When the optical path\nlength (L=80 {\\mu}m) is shorter than the optical (for wavelength,\n{\\lambda}=632.8 nm) coherence length inside the magnetic nanofluid under\napplied field, a Debye diffraction ring pattern is observed; while for longer\npath length (L=1mm), a corona ring of scattered light is observed. Analysis of\nDebye diffraction ring pattern suggests the formation of 3D hexagonal crystal\nstructure, where the longitudinal and lateral inter-column spacings are 5.281\nand 7.344 microns, respectively. Observation of speckles within the Debye\ndiffraction pattern confirms the presence of certain degree of structural\ndisorder within the crystal structure, which can be tuned by controlling the\napplied field strength, nanoparticle size and particle volume fraction. Our\nresults provide a new approach to develop next generation of tunable photonic\ndevices, based on simultaneous harnessing of the properties of disordered\nphotonic glass and 3D photonic crystal.",
        "positive": "Crossover between Equilibrium and Shear-controlled Dynamics in Sheared\n  Liquids: We present a numerical simulation study of a simple monatomic Lennard-Jones\nliquid under shear flow, as a function of both temperature and shear rate. By\ninvestigating different observables we find that i) It exists a line in the\n(temperature-shear) plane that sharply marks the boarder between an\n``equilibrium'' and a ``shear-controlled'' region for both the dynamic and the\nthermodynamic quantities; and ii) Along this line the structural relaxation\ntime, is proportional to the inverse shear rate, i.e. to the typical time-scale\nintroduced by the shear flow. Above the line the liquid dynamics is unaffected\nby the shear flow, while below it both temperature and shear rate control the\nparticle motion."
    },
    {
        "anchor": "How Do Clusters in Phase-Separating Active Matter Systems Grow? A study\n  for Vicsek activity in systems undergoing vapor-solid transition: Via molecular dynamics simulations we have studied kinetics of vapor-\"solid\"\nphase transition in an active matter model in which self-propulsion is\nintroduced via the well-known Vicsek rule. The overall density of the particles\nis chosen in such a way that the evolution morphology consists of disconnected\nclusters that are defined as regions of high density of particles. Our focus\nhas been on understanding the influence of the above mentioned self-propulsion\non structure and growth of these clusters by comparing the results with those\nfor the passive limit of the model that also exhibits vapor-\"solid\" transition.\nWhile in the passive case the growth occurs due to standard diffusive\nmechanism, the Vicsek activity leads to a very rapid growth, via a process that\nis practically equivalent to the ballistic aggregation mechanism. The emerging\ngrowth law in the latter case has been accurately estimated and explained by\ninvoking information on velocity and structural aspects of the clusters into a\nrelevant theory. Some of these results are also discussed with reference to a\nmodel for the active Brownian particles.",
        "positive": "Hydration of an apolar solute in a two-dimensional waterlike lattice\n  fluid: In a previous work, we investigated a two-dimensional lattice-fluid model,\ndisplaying some waterlike thermodynamic anomalies. The model, defined on a\ntriangular lattice, is now extended to aqueous solutions with apolar species.\nWater molecules are of the \"Mercedes Benz\" type, i.e., they possess a D3\n(equilateral triangle) symmetry, with three equivalent bonding arms. Bond\nformation depends both on orientation and local density. The insertion of inert\nmolecules displays typical signatures of hydrophobic hydration: large positive\ntransfer free energy, large negative transfer entropy (at low temperature),\nstrong temperature dependence of the transfer enthalpy and entropy, i.e., large\n(positive) transfer heat capacity. Model properties are derived by a\ngeneralized first order approximation on a triangle cluster."
    },
    {
        "anchor": "Structures of local rearrangements in soft colloidal glasses: We image local structural rearrangements in soft colloidal glasses under\nsmall periodic perturbations induced by thermal cycling. Local structural\nentropy $S_{2}$ positively correlates with observed rearrangements in colloidal\nglasses. The high $S_{2}$ values of the rearranging clusters in glasses\nindicate that fragile regions in glasses are structurally less correlated,\nsimilar to structural defects in crystalline solids. Slow-evolving high $S_{2}$\nspots are capable of predicting local rearrangements long before the\nrelaxations occur, while fluctuation-created high $S_{2}$ spots best correlate\nwith local deformations right before the rearrangement events. Local free\nvolumes are also found to correlate with particle rearrangements at extreme\nvalues, although the ability to identify relaxation sites is substantially\nlower than $S_{2}$. Our experiments provide an efficient structural identifier\nfor the fragile regions in glasses, and highlight the important role of\nstructural correlations in the physics of glasses.",
        "positive": "Scaling exponents of Forced Polymer Translocation through a nano-pore: We investigate several scaling properties of a translocating homopolymer\nthrough a thin pore driven by an external field present inside the pore only\nusing Langevin Dynamics (LD) simulation in three dimension (3D). Specifically\nmotivated by several recent theoretical and numerical studies that are\napparently at odds with each other, we determine the chain length dependence of\nthe scaling exponents of the average translocation time, the average velocity\nof the center of mass, $<v_{CM}>$, the effective radius of gyration during the\ntranslocation process, and the scaling exponent of the translocation coordinate\n($s$-coordinate) as a function of the translocation time. We further discuss\nthe possibility that in the case of driven translocation the finite pore size\nand its geometry could be responsible that the veclocity scaling exponent is\nless than unity and discuss the dependence of the scaling exponents on the pore\ngeometry for the range of $N$ studied here."
    },
    {
        "anchor": "Critical Phenomenon of the Order-Disorder Transition in Incompressible\n  Flocks: We study incompressible systems of motile particles with alignment\ninteractions. Unlike their compressible counterparts, in which the\norder-disorder (i.e., moving to static) transition, tuned by either noise or\nnumber density, is discontinuous, in incompressible systems this transition can\nbe continuous, and belongs to a new universality class. We calculate the\ncritical exponents to $O(\\epsilon)$in an $\\epsilon=4-d$ expansion, and derive\ntwo exact scaling relations. This is the first analytic treatment of a phase\ntransition in a new universality class in an active system.",
        "positive": "Thermally excited capillary waves at vapor/liquid interfaces of\n  water-alcohol mixtures: The density profiles of liquid/vapor interfaces of water-alcohol (methanol,\nethanol and propanol) mixtures were studied by surface sensitive synchrotron\nX-ray scattering techniques. X-ray reflectivity and diffuse scattering\nmeasurements, from the pure and mixed liquids, were analyzed in the framework\nof capillary-wave theory to address the characteristics length-scales of the\nintrinsic roughness and the shortest capillary-wavelength (alternatively, the\nupper wave-vector cutoff in capillary wave theory). Our results establish that\nthe intrinsic roughness is dominated by average interatomic distances. The\nextracted effective upper wave-vector cutoff indicates capillary wave theory\nbreaks-down at distances on order of bulk correlation lengths."
    },
    {
        "anchor": "Self-Propulsion of a Metallic Superoleophobic Micro-Boat: The self-propulsion of a heavy, superoleophobic, metallic micro-boat carrying\na droplet of various aqueous alcohol solutions as a fuel tank is reported. The\nmicro boat is driven by the solutocapillary Marangoni flow. The jump in the\nsurface tension owing to the condensation of alcohols on the water surface was\nestablished experimentally. Maximal velocities of the self-propulsion were\nregistered as high as 0.05 m/s. The maximal velocity of the center mass of the\nboat correlates with the maximal change in the surface tension, due to the\ncondensation of alcohols. The mechanism of the self-locomotion is discussed.\nThe phenomenological dynamic model describing the self-propulsion is reported.",
        "positive": "Soliton attenuation and emergent hydrodynamics in fragile matter: Disordered packings of soft grains are fragile mechanical systems that loose\nrigidity upon lowering the external pressure towards zero. At zero pressure, we\nfind that any infinitesimal strain-impulse propagates initially as a non-linear\nsolitary wave progressively attenuated by disorder. We demonstrate that the\nparticle fluctuations generated by the solitary-wave decay, can be viewed as a\ngranular analogue of temperature. Their presence is manifested by two emergent\nmacroscopic properties absent in the unperturbed granular packing: a finite\npressure that scales with the injected energy (akin to a granular temperature)\nand an anomalous viscosity that arises even when the microscopic mechanisms of\nenergy dissipation are negligible. Consistent with the interpretation of this\nstate as a fluid-like thermalized state, the shear modulus remains zero.\nFurther, we follow in detail the attenuation of the initial solitary wave\nidentifying two distinct regimes : an initial exponential decay, followed by a\nlonger power law decay and suggest simple models to explain these two regimes."
    },
    {
        "anchor": "Optical and structural properties of starch films formed on drying\n  droplets of gelatinized starch solutions: We report the optical and structural properties of starch films formed on\ndrying droplets of starch solutions on a flat substrate. The starch films\nformed after drying are circular in shape and have an azimuthally symmetric\n\"M-shaped\" height profile along their diameter. These films are found to be\nsemi-crystalline in nature and transparent in visible light. Our experimental\nresults show that these films are optically uniaxial at their center but\nbiaxial away from the center. The variation of birefringence along the radial\ndirection is studied for the films formed after drying droplets with different\nvolumes and starch concentrations. The cryo-SEM studies on the drying droplets\nand the films reveal the micro-structures and the possible origin of\nbirefringence of these films.",
        "positive": "Circularly-polarized plane waves in a deformed Hadamard material: Small amplitude inhomogeneous plane waves propagating in any direction in a\nhomogeneously deformed Hadamard material are considered. Conditions for\ncircular polarization are established. The analysis relies on the use of\ncomplex vectors (or bivectors) to describe the slowness and the polarization of\nthe waves. Generally, homogeneous circularly-polarized plane waves may\npropagate in only two directions, the directions of the acoustic axes, in a\nhomogeneously deformed Hadamard material. For inhomogeneous\ncircularly-polarized plane waves, the number of possibilities is far greater.\nThey include an infinity of \"transverse waves\", as well as \"longitudinal\nwaves\", and the superposition of \"transverse waves\" and \"longitudinal waves\",\nwhere \"transverse\" and \"longitudinal\" are used in the bivector sense. Each and\nevery possibility of circular polarization is examined in turn, and explicit\nexamples of solutions are given in every case."
    },
    {
        "anchor": "Unveiling two types of local order in liquid water using machine\n  learning: Machine learning methods are being explored in many areas of science, with\nthe aim of finding solution to problems that evade traditional scientific\napproaches due to their complexity. In general, an order parameter capable of\nidentifying two different phases of matter separated by a correspond- ing phase\ntransition is constructed based on symmetry arguments. This parameter measures\nthe degree of order as the phase transition proceeds. However, when the two\ndistinct phases are highly disordered it is not trivial to identify broken\nsymmetries with which to find an order parameter. This poses an excellent\nproblem to be addressed using machine learning procedures. Room tem- perature\nliquid water is hypothesized to be a supercritical liquid, with fluctuations of\ntwo different molecular orders associated to two parent liquid phases, one with\nhigh density and another one with low density. The validity of this hypothesis\nis linked to the existence of an order parameter capable of identifying the two\ndistinct liquid phases and their fluctuations. In this work we show how two\ndifferent machine learning procedures are capable of recognizing local order in\nliquid water. We argue that when in order to learn relevant features from this\ncomplexity, an initial, physically motivated preparation of the available data\nis as important as the quality of the data set, and that machine learning can\nbecome a successful analysis tool only when coupled to high level physical\ninformation.",
        "positive": "Complex Dynamics of a Bilamellar Vesicle as a Simple Model for\n  Leukocytes: The influence of the internal structure of a biological cell (e.g., a\nleukocyte) on its dynamics and rheology is not yet fully understood. By using\n2D numerical simulations of a bilamellar vesicle (BLV) consisting of two\nvesicles as a cell model, we find that increasing the size of the inner vesicle\n(mimicking the nucleus) triggers a tank-treading-to-tumbling transition. A new\ndynamical state is observed, the undulating motion: the BLV inclination with\nrespect to the imposed flow oscillates while the outer vesicle develops\nrotating lobes. The BLV exhibits a non-Newtonian behavior with a time-dependent\napparent viscosity during its unsteady motion. Depending on its inclination and\non its inner vesicle dynamical state, the BLV behaves like a solid or a liquid."
    },
    {
        "anchor": "Probing surfactant bilayer interactions by tracking optically trapped\n  single nanoparticles: Single-particle tracking and optical tweezers are powerful techniques for\nstudying diverse processes at the microscopic scale. The stochastic behavior of\na microscopically observable particle contains information about its\ninteraction with surrounding molecules, and an optical tweezer can further\nfacilitate this observation with its ability to constrain the particle to an\narea of interest. Although these techniques found their initial applications in\nbiology, they can also shed new light on colloid and interface phenomena by\nunveiling nanoscale morphologies and molecular-level interactions in real time,\nwhich have been obscured in traditional ensemble analysis. Here we demonstrate\nthe application of single-particle tracking and optical tweezers for studying\nmolecular interactions at solid-liquid interfaces. Specifically, we investigate\nthe behavior of surfactants at the water-glass interface by tracing their\ninteractions with gold nanoparticles that are optically trapped on these\nmolecules. We discover the underlying mechanisms governing the particle motion,\nwhich can be explained by hydrophobic interactions, disruptions, and\nrearrangements among surfactant monomers at the interfaces. Such\ninterpretations are further supported by statistical analysis of an individual\ntrajectory and comparison to theoretical predictions. Our findings provide new\ninsights into the surfactant dynamics in this specific system but also\nillustrate the promise of single-particle tracking and optical manipulation in\nstudying nanoscale physics and chemistry of surfaces and interfaces.",
        "positive": "Charge Fluctuations and Counterion Condensation: We predict a condensation phenomenon in an overall neutral system, consisting\nof a single charged plate and its oppositely charged counterions. Based on the\n``two-fluid'' model, in which the counterions are divided into a ``free'' and a\n``condensed'' fraction, we argue that for high surface charge, fluctuations can\nlead to a phase transition in which a large fraction of counterions is\ncondensed. Furthermore, we show that depending on the valence, the condensation\nis either a first-order or a smooth transition."
    },
    {
        "anchor": "Clustering and gelation of hard spheres induced by the Pickering effect: A mixture of hard-sphere particles and model emulsion droplets is studied\nwith a Brownian dynamics simulation. We find that the addition of nonwetting\nemulsion droplets to a suspension of pure hard spheres can lead to both\ngas-liquid and fluid-solid phase separations. Furthermore, we find a stable\nfluid of hard-sphere clusters. The stability is due to the saturation of the\nattraction that occurs when the surface of the droplets is completely covered\nwith colloidal particles. At larger emulsion droplet densities a percolation\ntransition is observed. The resulting networks of colloidal particles show\ndynamical and mechanical properties typical of a colloidal gel. The results of\nthe model are in good qualitative agreement with recent experimental findings\n[E. Koos and N. Willenbacher, Science 331, 897 (2011)] in a mixture of\ncolloidal particles and two immiscible fluids.",
        "positive": "Craters Formed in Granular Beds by Impinging Jets of Gas: When a jet of gas impinges vertically on a granular bed and forms a crater,\nthe grains may be moved by several different mechanisms: viscous erosion,\ndiffused gas eruption, bearing capacity failure, and/or diffusion-driven\nshearing. The relative importance of these mechanisms depends upon the flow\nregime of the gas, the mechanical state of the granular material, and other\nphysical parameters. Here we report research in two specific regimes: viscous\nerosion forming scour holes as a function of particle size and gravity; and\nbearing capacity failure forming deep transient craters as a function of soil\ncompaction."
    },
    {
        "anchor": "Evidence of a one-dimensional thermodynamic phase diagram for simple\n  glass-formers: The glass transition plays a central role in nature as well as in industry,\nranging from biological systems such as proteins and DNA to polymers and\nmetals. Yet the fundamental understanding of the glass transition which is a\nprerequisite for optimized application of glass formers is still lacking. Glass\nformers show motional processes over an extremely broad range of timescales,\ncovering more than ten orders of magnitude, meaning that a full understanding\nof the glass transition needs to comprise this tremendous range in timescales.\nHere we report on first-time simultaneous neutron and dielectric spectroscopy\ninvestigations of three glass-forming liquids, probing in a single experiment\nthe full range of dynamics. For two van der Waals liquids we locate in the\npressure-temperature phase diagram lines of identical dynamics of the molecules\non both second and picosecond timescales. This confirms predictions of the\nisomorph theory and effectively reduces the phase diagram from two to one\ndimension. The implication is that dynamics on widely different timescales are\ngoverned by the same underlying mechanisms.",
        "positive": "Mixtures of anisotropic and spherical colloids: Phase behavior,\n  confinement, percolation phenomena and kinetics: Purely entropic systems such as suspensions of hard rods, platelets and\nspheres show rich phase behavior. Rods and platelets have successfully been\nused as models to predict the equilibrium properties of liquid crystals for\nseveral decades. Over the past years hard particle models have also been\nstudied in the context of non-equilibrium statistical mechanics, in particular\nregarding the glass transition, jamming, sedimentation and crystallization.\nRecently suspensions of hard anisotropic particles also moved into the focus of\nmaterials scientists who work on conducting soft matter composites. An\ninsulating polymer resin that is mixed with conductive filler particles becomes\nconductive when the filler percolates. In this context the mathematical topic\nof connectivity percolation finds an application in modern nano-technology. In\nthis article, we briefly review recent work on the phase behavior, confinement\neffects, percolation transition and phase transition kinetics in hard particle\nmodels. In the first part, we discuss the effects that particle anisotropy and\ndepletion have on the percolation transition. In the second part, we present\nresults on the kinetics of the liquid-to-crystal transition in suspensions of\nspheres and of ellipsoids."
    },
    {
        "anchor": "Transport in polymer-gel composites: Theoretical methodology and\n  response to an electric field: A theoretical model of electromigrative, diffusive and convectivetransport\npolymer-gel composites is presented. Bulk properties are derived from the\nstandard electrokinetic model with an impenetrable charged sphere embedded in\nan electrolyte-saturated Brinkman medium. Because the microstructure can be\ncarefully controlled, these materials are promising candidates for enhanced\ngel-electrophoresis, chemical sensing, drug delivery, and microfluidic pumping\ntechnologies. The methodology provides `exact' solutions for situations where\nperturbations from equilibrium are induced by gradients of electrostatic\npotential, concentration and pressure. While the volume fraction of the\ninclusions should be small, Maxwell's well-known theory of conduction suggests\nthat the theory may also be accurate at moderate volume fractions. In this\nwork, the model is used to compute ion fluxes, electrical current density, and\nconvective flow induced by an applied electric field. The\nelectric-field-induced (electro-osmotic) flow is a sensitive indicator of the\ninclusion zeta-potential and size, electrolyte concentration, and Darcy\npermeability of the gel, while the electrical conductivity increment is most\noften independent of the polymer gel, and is much less sensitive to particle\nand electrolyte characteristics.",
        "positive": "Persistence in Brownian motion of an ellipsoidal particle in two\n  dimensions: We investigate the persistence probability $p(t)$ of the position of a\nBrownian particle with shape asymmetry in two dimensions. The persistence\nprobability is defined as the probability that a stochastic variable has not\nchanged it's sign in the given time interval. We explicitly consider two cases\n-- diffusion of a free particle and that of harmonically trapped particle. The\nlater is particularly relevant in experiments which uses trapping and tracking\ntechniques to measure the displacements. We provide analytical expressions of\n$p(t)$ for both the scenarios and show that in the absence of the shape\nasymmetry the results reduce to the case of an isotropic particle. The\nanalytical expressions of $p(t)$ are further validated against numerical\nsimulation of the underlying overdamped dynamics. We also illustrate that\n$p(t)$ can be a measure to determine the shape asymmetry of a colloid and the\ntranslational and rotational diffusivities can be estimated from the measured\npersistence probability. The advantage of this method is that it does not\nrequire the tracking of the orientation of the particle."
    },
    {
        "anchor": "Lamellar order, microphase structures and glassy phase in a field\n  theoretic model for charged colloids: In this paper we present a detailed analytical study of the phase diagram and\nof the structural properties of a field theoretic model with a short-range\nattraction and a competing long-range screened repulsion. We provide a full\nderivation and expanded discussion and digression on results previously\nreported briefly in M. Tarzia and A. Coniglio, Phys. Rev. Lett. 96, 075702\n(2006). The model contains the essential features of the effective interaction\npotential among charged colloids in polymeric solutions. We employ the\nself-consistent Hartree approximation and a replica approach, and we show that\nvarying the parameters of the repulsive potential and the temperature yields a\nphase coexistence, a lamellar and a glassy phase. Our results suggest that the\ncluster phase observed in charged colloids might be the signature of an\nunderlying equilibrium lamellar phase, hidden on experimental time scales, and\nemphasize that the formation of microphase structures may play a prominent role\nin the process of colloidal gelation.",
        "positive": "Exploring different regimes in finite-size scaling of the droplet\n  condensation-evaporation transition: We present a finite-size scaling analysis of the droplet\ncondensation-evaporation transition of a lattice gas (in two and three\ndimensions) and a Lennard-Jones gas (in three dimensions) at fixed density.\nParallel multicanonical simulations allow sampling of the required system sizes\nwith precise equilibrium estimates. In the limit of large systems, we verify\nthe theoretical leading-order scaling prediction for both the transition\ntemperature and the finite-size rounding. In addition, we present an emerging\nintermediate scaling regime, consistent in all considered cases and with\nsimilar recent observations for polymer aggregation. While the intermediate\nregime locally may show a different effective scaling, we show that it is a\ngradual crossover to the large-system scaling behavior by including empirical\nhigher-order corrections. This implies that care has to be taken when\nconsidering scaling ranges, possibly leading to completely wrong predictions\nfor the thermodynamic limit. In this study, we consider a crossing of the phase\nboundary orthogonal to the usual fixed temperature studies. We show that this\nis an equivalent approach and, under certain conditions, may show smaller\nfinite-size corrections."
    },
    {
        "anchor": "Interface stability, interface fluctuations, and the Gibbs-Thomson\n  relation in motility-induced phase separations: Minimal models of self-propelled particles with short-range volume exclusion\ninteractions have been shown to exhibit signatures of phase separation. Here I\nshow that the observed interfacial stability and fluctuations in\nmotility-induced phase separations (MIPS) can be explained by modeling the\nmicroscopic dynamics of the active particles in the interfacial region. In\naddition, I demonstrate the validity of the Gibbs-Thomson relation in MIPS,\nwhich provides a functional relationship between the size of a condensed drop\nand its surrounding vapor concentration. As a result, the coarsening dynamics\nof MIPS at vanishing supersaturation follows the classic Lifshitz-Slyozov\nscaling law at the late stage.",
        "positive": "Spherical Polymer Brushes Under Good Solvent Conditions: Molecular\n  Dynamics Results Compared to Density Functional Theory: A coarse grained model for flexible polymers end-grafted to repulsive\nspherical nanoparticles is studied for various chain lengths and grafting\ndensities under good solvent conditions, by Molecular Dynamics methods and\ndensity functional theory. With increasing chain length the monomer density\nprofile exhibits a crossover to the star polymer limit. The distribution of\npolymer ends and the linear dimensions of individual polymer chains are\nobtained, while the inhomogeneous stretching of the chains is characterized by\nthe local persistence lengths. The results on the structure factor of both\nsingle chain and full spherical brush as well as the range of applicability of\nthe different theoretical tools are presented. Eventually an outlook on\nexperiments is given."
    },
    {
        "anchor": "Kinetic theory of binary particles with unequal mean velocities and\n  non-equipartition energies: The hydrodynamic conservation equations and constitutive relations for a\nbinary granular mixture composed of smooth, nearly elastic, hard spheres with\nnon-equipartition energies and different mean velocities are derived. This\nresearch is aimed to build three-dimensional kinetic theory to characterize the\nbehaviors of two species of particles suffering different forces. The standard\nEnskog method is employed assuming a Maxwell velocity distribution for each\nspecies of particles. The collision components of the stress tensor and the\nother parameters are calculated from the zeroth- and first-order approximation.\nOur results demonstrate that three factors, namely the ratios between two\ngranular masses, temperatures and mean velocities all play important roles in\nthe stress-strain relation of the binary mixture. The collision frequency and\nthe solid viscosity escalate with increasing of two granular temperatures and\nare maximized when both of two granular temperatures reach maximums. The first\npart of the energy source varies greatly with the mean velocities of spheres of\ntwo species, and further, it reaches maximum at the maximum of relative\nvelocity between two mean velocities of spheres of two species.",
        "positive": "Glassy swirls of active dumbbells: The dynamics of a dense binary mixture of soft dumbbells, each subject to an\nactive propulsion force and thermal fluctuations, shows a sudden arrest, first\nto a translational then to a rotational glass, as one reduces temperature $T$\nor the self-propulsion force $f$. Is the temperature-induced glass different\nfrom the activity-induced glass? To address this question, we monitor the\ndynamics along an iso-relaxation-time contour in the $(T-f)$ plane. We find\ndramatic differences both in the fragility and in the nature of dynamical\nheterogeneity which characterise the onset of glass formation - the\nactivity-induced glass exhibits large swirls or vortices, whose scale is set by\nactivity, and appears to diverge as one approaches the glass transition. This\nlarge collective swirling movement should have implications for collective cell\nmigration in epithelial layers."
    },
    {
        "anchor": "On few aspects of the dynamics of granular matter: This paper, in French, describes a series of completely different behaviours\nof the mechanics of granular matter, which are obtained experimentally using\nperiodic forcing at different amplitude, frequency and orientation. It starts\nwith the problem of granular dissipative gas which has been investigated in\nmicro-gravity ; it is found that such a gas exists only at very low density ;\nit is shown also that clustering occurs at larger density. Is this a phase\ntransition ? The problem of dissipative Sinai billiard is then investigated\nbriefly ; is it ergodic ? An experiment on propagation of acoustic wave is\nstudied, with peculiar attention paid to scattering and diffusion that occurs\nwhen acoustic wavelength is comparable to the grain size. A third experiment\ndemonstrates that bulk convection can be induced by slow (quasi static)\nhorizontal forcing ; this flow is related to the quasi static rheology of\ngranular matter, but looks rather like convection occurring under \"dynamic\nvibration\". A fourth experiment describes pure inertial effect, making the sand\nbehaving as a perfect (non viscous) fluid ; in particular, it is shown that a\nstatic swell 9that does not propagate) is enforced at the interface between\nliquid and sand by strong periodic horizontal forcing . Pacs # : 5.40 ; 45.70 ;\n62.20 ; 83.70.Fn",
        "positive": "Higher-Order Singularities without Glass-Glass Transitions: Within the framework of mode-coupling theory, the glass-transition scenario\nis investigated for a system of particles interacting with a hard-core\nrepulsion and an additional square-shoulder soft core at larger distances. The\nstatic structure is calculated from the potential in Percus-Yevick\napproximation. For certain widths of the shoulder, the exponent parameter\nlambda along the glass-transition line shows a double peak. At both peaks,\nlambda can reach unity indicating the existence of higher-order\nglass-transition singularities. It is shown that these higher-order\nsingularities originate from a line of avoided glass-glass transitions."
    },
    {
        "anchor": "Polymer electrolytes in strong external electric fields: Modification of\n  structure and dynamics: We present the results from an extensive atomistic molecular dynamics\nsimulation study of poly(ethylene oxide) (PEO) doped with various amounts of\nlithium-bis(trifluoromethane)sulfonimide (LiTFSI) salt under the influence of\nexternal electric field strengths up to $1\\,$V/nm. The motivation stems from\nrecent experimental reports on the nonlinear response of mobilities to the\napplication of an electric field in such electrolyte systems and arising\nspeculations on field-induced alignment of the polymer chains, creating\nchannel-like structures that facilitate ion passage. Hence, we systematically\nexamine the electric field impact on the lithium coordination environment,\npolymer structure as well as ionic transport properties and further present a\nprocedure to quantify the susceptibility of both structural and dynamical\nobservables to the external field. Our investigation reveals indeed a\ncoiled-to-stretched transformation of the PEO strands along with a concurrent\nnonlinear behavior of the dynamic properties. However, from studying the\ntemporal response of the unperturbed electrolyte system to field application we\nare able to exclude a structurally conditioned enhancement of ion transport and\nsurprisingly observe a slowing down. A microscopic understanding is supplied.",
        "positive": "Liquid droplets on a free-standing glassy membrane: deformation through\n  the glass transition: In this study, micro-droplets are placed on thin, glassy, free-standing films\nwhere the Laplace pressure of the droplet deforms the free-standing film,\ncreating a bulge. The film's tension is modulated by changing temperature\ncontinuously from well below the glass transition into the melt state of the\nfilm. The contact angle of the liquid droplet with the planar film as well as\nthe angle of the bulge with the film are measured and found to be consistent\nwith the contact angles predicted by a force balance at the contact line."
    },
    {
        "anchor": "Effect of pressure on the number of dynamically correlated molecules\n  when approaching the glass transition: We characterize the heterogeneous character of the dynamics of liquids\napproaching the glass transition through an experimental determination of the\nnumber of dynamically correlated molecules N_{corr} as obtained from dynamical\nsusceptibilities. To do so, we have obtained a new set of dielectric\nspectroscopy data for liquid dibutyl-phtalate on a fine and extended\ntemperature and pressure grid, and we have used it in conjunction with\nhigh-pressure data from the literature. We have been able to evaluate the\ncontributions to N_{corr} that are due to fluctuations associated with density\nand with temperature separately, thereby improving the estimate of N_{corr}. We\nfind that N_{corr} increases along the glass transition line, and more\ngenerally along any isochronic line, as pressure increases (up to 1 GPa), a\nresult which is at odds with recent reports and theoretical predictions.",
        "positive": "Two-dimensional percolation phenomena of single-component linear\n  homopolymer brushes: Percolation phenomena of homopolymer brushes on a planar substrate are\nsimulated using the molecular Monte Carlo method in 3 dimensions. The grafted\npolymers are isolated from each other at extremely low grafting density,\nwhereas a continuous polymer layer covers the whole substrate when the density\nrises to extremely high values. This indicates that percolation clusters of the\ngrafted polymers, bridging both the edges of the substrate, appear at an\nintermediate density. We construct phase diagrams of this percolation\nphenomenon. Critical phenomena at the transition are also studied."
    },
    {
        "anchor": "Shock-Sensitivity in Shell-Like Structures: with Simulations of\n  Spherical Shell Buckling: Under increasing compression, an unbuckled shell is in a metastable state\nwhich becomes increasingly precarious as the buckling load is approached. So to\ninduce premature buckling a lateral disturbance will have to overcome a\ndecreasing energy barrier which reaches zero at buckling. Two archetypal\nproblems that exhibit a severe form of this behaviour are the\naxially-compressed cylindrical shell and the externally pressurized spherical\nshell. Focussing on the cylinder, a non-destructive technique was recently\nproposed to estimate the 'shock sensitivity' of a laboratory specimen using a\nlateral probe to measure the nonlinear load-deflection characteristic. If a\nsymmetry-breaking bifurcation is encountered on the path, computer simulations\nshowed how this can be suppressed by a controlled secondary probe. Here, we\nextend our understanding by assessing in general terms how a single control can\ncapture remote saddle solutions: in particular how a symmetric probe could\nlocate an asymmetric solution. Then, more specifically, we analyse the\nspherical shell with point and ring probes, to test the procedure under\nchallenging conditions to assess its range of applicability. Rather than a\nbifurcation, the spherical shell offers the challenge of a de-stabilizing fold\n(limit point) under the rigid control of the probe.",
        "positive": "Self diffusion of reversibly aggregating spheres: Reversible diffusion limited cluster aggregation of hard spheres with rigid\nbonds was simulated and the self diffusion coefficient was determined for\nequilibrated systems. The effect of increasing attraction strength was\ndetermined for systems at different volume fractions and different interaction\nranges. It was found that the slowing down of the diffusion coefficient due to\ncrowding is decoupled from that due to cluster formation. The diffusion\ncoefficient could be calculated from the cluster size distribution and became\nzero only at infinite attraction strength when permanent gels are formed. It is\nconcluded that so-called attractive glasses are not formed at finite\ninteraction strength."
    },
    {
        "anchor": "Gravity effects on mixing with magnetic micro-convection in\n  microfluidics: Mixing remains an important problem for development of successful\nmicrofluidic and lab-on-a-chip devices, where simple and predictable systems\nare particularly interesting. One is magnetic micro-convection, an instability\nhappening on the interface of miscible magnetic and non-magnetic fluids in a\nHele-Shaw cell under applied field. Previous work proved that Brinkman model\nquantitatively explains the experiments. However, a gravity caused convective\nmotion complicated the tests. Here we first improve the experimental system to\nexclude the gravitational convective motion. Afterwards, we observe and\nquantify how gravity and laminar flow play an important role in stabilizing the\nperturbations that create the instability. Accordingly, we improve our\ntheoretical model and perform linear analysis. Two dimensionless quantities\nexplain the experimental observations of change in critical field needed for\ninstability and characteristic size of the emerging pattern. Finally, we\ndiscuss the conditions at which gravity plays an important role in microfluidic\nsystems.",
        "positive": "On intermittency in sheared granular systems: We consider a system of granular particles, modeled by two dimensional\nfrictional elastic disks, that is exposed to externally applied time-dependent\nshear stress in a planar Couette geometry. We concentrate on the external\nforcing that produces intermittent dynamics of stick-slip type. In this regime,\nthe top wall remains almost at rest until the applied stress becomes\nsufficiently large, and then it slips. We focus on the evolution of the system\nas it approaches a slip event. Our main finding is that there are two distinct\ngroups of measures describing system behavior before a slip event. The first\ngroup consists of global measures defined as system-wide averages at a fixed\ntime. Typical examples of measures in this group are averages of the normal or\ntangent forces acting between the particles, system size and number of contacts\nbetween the particles. These measures do not seem to be sensitive to an\napproaching slip event. On average, they tend to increase linearly with the\nforce pulling the spring. The second group consists of the time-dependent\nmeasures that quantify the evolution of the system on a micro (particle) or\nmesoscale. Measures in this group first quantify the temporal differences\nbetween two states and only then aggregate them to a single number. For\nexample, Wasserstein distance quantitatively measures the changes of the force\nnetwork as it evolves in time while the number of broken contacts quantifies\nthe evolution of the contact network. The behavior of the measures in the\nsecond group changes dramatically before a slip event starts. They increase\nrapidly as a slip event approaches, indicating a significant increase in\nfluctuations of the system before a slip event is triggered."
    },
    {
        "anchor": "Increasing the magnetic sensitivity of liquid crystals by rod-like\n  magnetic nanoparticles: Magnetic Fr\\'eedericksz transition was studied in ferronematics based on the\nnematic liquid crystal 4-(trans-4'-n-hexylcyclohexyl)-isothiocyanatobenzene\n(6CHBT). 6CHBT was doped with rod-like magnetic particles of different size and\nvolume concentration. The volume concentrations of magnetic particles in the\nprepared ferronematics were $\\phi_1$ = 10$^{-4}$ and $\\phi_2$ = 10$^{-3}$. The\nstructural changes were observed by capacitance measurements that demonstrate a\nsignificant influence of the concentration, the shape anisotropy, and/or the\nsize of the magnetic particles on the magnetic response of these ferronematics.",
        "positive": "Monte Carlo Simulation of Long Hard-Sphere Polymer Chains in Two to Five\n  Dimensions: We perform simulations for long hard-sphere polymer chains using a recently\ndeveloped binary-tree based Monte Carlo method. Systems in two to five\ndimensions with free and periodic boundary conditions and up to $10^7$ repeat\nunits are considered. We focus on the scaling properties of the end-to-end\ndistance and on the entropy and their dependence on the sphere diameter. To\nthis end new methods for measuring entropy and its derivatives are introduced.\nBy determining the Flory exponent $\\nu$ and the weakly universal amplitude\nratio of end-to-end distance to radius of gyration we find that the system\ngenerally reproduces the behavior of self-avoiding lattice walks in strong\nsupport of universality."
    },
    {
        "anchor": "Numerical deflation of beach balls with various Poisson's ratios: from\n  sphere to bowl's shape: We present a numerical study of the shape taken by a spherical elastic\nsurface when the volume it encloses is decreased. For the range of 2D\nparameters where such surface may modelize a thin shell of an isotropic elastic\nmaterial, the mode of deformation that develops a single depression is\ninvestigated in detail. It first occurs via buckling from sphere toward an\naxisymmetric dimple, followed by a second buckling where the depression loses\nits axisymmetry, by folding along portions of meridians. We could exhibit\nunifying master curves for the relative volume variation at which first and\nsecond buckling occur, and clarify the role of the Poisson's ratio. After the\nsecond buckling, the number of folds and inner pressure are investigated,\nallowing to infer shell features from mere observation and/or knowledge of\nexternal constraints.",
        "positive": "Geared topological metamaterials with tunable mechanical stability: The classification of materials into insulators and conductors has been\nshaken up by the discovery of topological insulators that conduct robustly at\nthe edge but not in the bulk. In mechanics, designating a material as\ninsulating or conducting amounts to asking if it is rigid or floppy. Although\nmechanical structures that display topological floppy modes have been proposed,\nthey are all vulnerable to global collapse. Here, we design and build\nmechanical metamaterials that are stable and yet capable of harboring protected\nedge and bulk modes, analogous to those in electronic topological insulators\nand Weyl semimetals. To do so, we exploit gear assemblies that, unlike point\nmasses connected by springs, incorporate both translational and rotational\ndegrees of freedom. Global structural stability is achieved by eliminating\ngeometrical frustration of collective gear rotations extending through the\nassembly. The topological robustness of the mechanical modes makes them\nappealing across scales from engineered macrostructures to networks of toothed\nmicrorotors of potential use in micro-machines."
    },
    {
        "anchor": "Disentangling the role of structure and friction in shear jamming: Amorphous packings of spheres have been intensely investigated in order to\nunderstand the mechanical and flow behaviour of dense granular matter, and to\nexplore universal aspects of the transition from fluid to structurally arrested\nor jammed states. Considerable attention has recently been focussed on\nanisotropic packings of frictional grains generated by shear deformation\nleading to shear jamming, which occurs below the jamming density for isotropic\npackings of frictionless grains. With the aim of disentangling the role of\nshear deformation induced structures and friction in generating shear jamming,\nwe study sheared assemblies of frictionless spheres computationally, over a\nwide range of densities, extending far below the isotropic jamming point. We\ndemonstrate the emergence of a variety of geometric features characteristic of\njammed packings with the increase of shear strain. The average contact number\nand the distributions of contact forces suggest the presence of a threshold\ndensity, well below the isotropic jamming point, above which a qualitative\nchange occurs in the jamming behaviour of sheared configurations. We show that\nabove this threshold density, friction stabilizes the sheared configurations we\ngenerate. Our results thus reveal the emergence of geometric features\ncharacteristic of jammed states as a result of shear deformation alone, while\nfriction is instrumental in stabilising packings over a range of densities\nbelow the isotropic jamming point.",
        "positive": "Structure formation in binary mixtures of lipids and detergents:\n  Self-assembly and vesicle division: Self-assembly dynamics in binary surfactant mixtures and structure changes of\nlipid vesicles induced by detergent solution are studied using coarse-grained\nmolecular simulations. Disk-shaped micelles, the bicelles, are stabilized by\ndetergents surrounding the rim of a bilayer disk of lipids. The self-assembled\nbicelles are considerably smaller than bicelles formed from vesicle rupture,\nand their size is determined by the concentrations of lipids and detergents and\nthe interactions between the two species. The detergent-adsorption induces\nspontaneous curvature of the vesicle bilayer and results in vesicle division\ninto two vesicles or vesicle rupture into worm-like micelles. The division\noccurs mainly via the inverse pathway of the modified stalk model. For large\nspontaneous curvature of the monolayers of the detergents, a pore is often\nopened, thereby leading to vesicle division or worm-like micelle formation."
    },
    {
        "anchor": "Paraboloidal Crystals: The interplay between order and geometry in soft condensed matter systems is\nan active field with many striking results and even more open problems. Ordered\nstructures on curved surfaces appear in multi-electron helium bubbles, viral\nand bacteriophage protein capsids, colloidal self-assembly at interfaces and in\nphysical membranes. Spatial curvature can lead to novel ground state\nconfigurations featuring arrays of topological defects that would be excited\nstates in planar systems. We illustrate this with a sequence of images showing\nthe Voronoi lattice (in gold) and the corresponding Delaunay triangulations (in\ngreen) for ten low energy configurations of a system of classical charges\nconstrained to lie on the surface of a paraboloid and interacting with a\nCoulomb potential. The parabolic geometry is considered as a specific\nrealization of the class of crystalline structures on two-dimensional\nRiemannian manifolds with variable Gaussian curvature and boundary.",
        "positive": "Mesoscopic simulations of anisotropic chemically-powered nanomotors: Chemically powered self-propelled colloids generate a motor force by\nconverting locally a source of energy into directed motion, a process that has\nbeen explored both in experiments and in computational models. The use of\nactive colloids as building blocks for nanotechnology opens the doors to\ninteresting applications, provided we understand the behaviour of these\nelementary constituents. We build a consistent mesoscopic simulation model for\nself-propelled colloids of complex shape with the aim of resolving the coupling\nbetween their translational and rotational motion. Considering a passive\nL-shaped colloidal particle, we study its Brownian dynamics and locate its\ncenter of hydrodynamics, the tracking point at which translation and rotation\ndecouple. The active L particle displays the same circling trajectories that\nhave been found experimentally, a result which we compare with the Brownian\ndynamics model. We put forward the role of hydrodynamics by comparing our\nresults with a fluid model in which the particles' velocities are reset\nrandomly. There, the trajectories only display random orientations. We obtain\nthese original simulation results without any parametrization of the algorithm,\nwhich makes it a useful method for the preliminary study of active colloids,\nprior to experimental work."
    },
    {
        "anchor": "Topology and Geometry of Smectic Order on Compact Curved Substrates: Smectic order on arbitrary curved substrate can be described by a\ndifferential form of rank one (1-form), whose geometric meaning is the\ndifferential of the local phase field of the density modulation. The exterior\nderivative of 1-form is the local dislocation density. Elastic deformations are\ndescribed by superposition of exact differential forms. We use the formalism of\ndifferential forms to systematically classify and characterize all low energy\nsmectic states on torus as well as on sphere. A two dimensional smectic order\nconfined on either manifold exhibits many topologically distinct low energy\nstates. Different states are not accessible from each other by local\nfluctuations. The total number of low energy states scales as the square root\nof the system area. We also address the energetics of 2D smectic on a curved\nsubstrate and calculate the mean field phase diagram of smectic on a thin\ntorus. Finally, we discuss the motion of disclinations for spherical smectics\nas low energy excitations, and illustrate the interesting connection between\nspherical smectic and the theory of elliptic functions.",
        "positive": "Measuring storage and loss moduli using optical tweezers: broadband\n  microrheology: We present an experimental procedure to perform broadband microrheological\nmeasurements with optical tweezers. A generalised Langevin equation is adopted\nto relate the time-dependent trajectory of a particle in an imposed flow to the\nfrequency-dependent moduli of the complex fluid. This procedure allows us to\nmeasure the material linear viscoelastic properties across the widest frequency\nrange achievable with optical tweezers."
    },
    {
        "anchor": "Buckling sheets open a door to understanding self-organization in soft\n  matter: This is an invited commentary on \"Geometrically incompatible confinement of\nsolids\", B. Davidovitch, Y. Sun and G. M. Grason (PNAS,\ndoi:10.1073/pnas.1815507116 , arxiv:1809.06919).",
        "positive": "Autonomous elastic microswimmer: A model of an autonomous three-sphere microswimmer is proposed by\nimplementing a coupling effect between the two natural lengths of an elastic\nmicroswimmer. Such a coupling mechanism is motivated by the previous models for\nsynchronization phenomena in coupled oscillator systems. We numerically show\nthat a microswimmer can acquire a nonzero steady state velocity and a finite\nphase difference between the oscillations in the natural lengths. These\nvelocity and phase difference are almost independent of the initial phase\ndifference. There is a finite range of the coupling parameter for which a\nmicroswimmer can have an autonomous directed motion. The stability of the phase\ndifference is investigated both numerically and analytically in order to\ndetermine its bifurcation structure."
    },
    {
        "anchor": "Molecular dynamics simulation of polymer helix formation using\n  rigid-link methods: Molecular dynamics simulations are used to study structure formation in\nsimple model polymer chains that are subject to excluded volume and torsional\ninteractions. The changing conformations exhibited by chains of different\nlengths under gradual cooling are followed until each reaches a state from\nwhich no further change is possible. The interactions are chosen so that the\ntrue ground state is a helix, and a high proportion of simulation runs succeed\nin reaching this state; the fraction that manage to form defect-free helices is\na function of both chain length and cooling rate. In order to demonstrate\nbehavior analogous to the formation of protein tertiary structure, additional\nattractive interactions are introduced into the model, leading to the\nappearance of aligned, antiparallel helix pairs. The simulations employ a\ncomputational approach that deals directly with the internal coordinates in a\nrecursive manner; this representation is able to maintain constant bond lengths\nand angles without the necessity of treating them as an algebraic constraint\nproblem supplementary to the equations of motion.",
        "positive": "Unbinding transitions of multicomponent membranes and strings: We present a theory of unbinding transitions for membranes that interact via\nshort and long receptor/ligand bonds. The detail of unbinding behavior of the\nmembranes is governed by the binding energies and concentrations of receptors\nand ligands. We investigate the unbinding behavior of these membranes with\nMonte Carlo simulations and via a comparison with strings. We derive the\nscaling laws for strings analytically. The exact analytic results provide\nscaling estimate for membranes in the vicinity of the critical point."
    },
    {
        "anchor": "A simple second order thermodynamic perturbation theory for associating\n  fluids: An approximation within Wertheim's second order perturbation theory is\nproposed which allows for the development of a general solution for pure\ncomponent fluids with an arbitrary number and functionality of association\nsites. The solution is closed, concise and general for all second order effects\nsuch as ring formation, steric hindrance and hydrogen bond cooperativity. The\napproach is validated by comparison to hydrogen bond structure data for liquid\nwater.",
        "positive": "Sliding drops across alternating hydrophobic and hydrophilic stripes: We perform a joint numerical and experimental study to sistematically\ncharacterize the motion of drops sliding over a periodic array of alternating\nhydrophobic and hydrophilic stripes with large wettability contrast, and\ntypical width of hundreds of $\\mu \\textrm{m}$. The fraction of the hydrophobic\nstripes has been varied from about 20% to 80%. The effects of the heterogeneous\npatterning can be described by a renormalized value of the critical Bond\nnumber, i.e. the critical dimensionless force needed to depin the drop before\nit starts to move. Close to the critical Bond number we observe a jerkily\nmotion characterized by an evident stick-slip dynamics. As a result,\ndissipation is strongly localized in time, and the mean velocity of the drops\ncan easily decrease by an order of magnitude compared to the sliding on\nhomogeneous surface. Lattice Boltzmann (LB) numerical simulations are crucial\nfor disclosing to what extent the sliding dynamics can be deduced from the\ncomputed balance of capillary, viscous and body forces at varying the Bond\nnumber, the surface composition and the liquid viscosity. Away from the\ncritical Bond number, we characterize both experimentally and numerically the\ndissipation inside the droplet by studying the relation between the average\nvelocity and the applied volume forces."
    },
    {
        "anchor": "Elasticity of arrested short-ranged attractive colloids: homogeneous and\n  heterogeneous glasses: We evaluate the elasticity of arrested short-ranged attractive colloids by\ncombining an analytically solvable elastic model with a hierarchical arrest\nscheme into a new approach, which allows to discriminate the microscopic\n(primary particle-level) from the mesoscopic (cluster-level) contribution to\nthe macroscopic shear modulus. The results quantitatively predict experimental\ndata in a wide range of volume fractions and indicate in which cases the\nrelevant contribution is due to mesoscopic structures. On this basis we propose\nthat different arrested states of short-ranged attractive colloids can be\nmeaningfully distinguished as homogeneous or heterogeneous colloidal glasses in\nterms of the length-scale which controls their elastic behavior.",
        "positive": "Delayed solidification of soft glasses: New experiments, and a\n  theoretical challenge: When subjected to large amplitude oscillatory shear stress, aqueous Laponite\nsuspensions show an abrupt solidification transition after a long delay time\ntc. We measure the dependence of tc on stress amplitude, frequency, and on the\nage-dependent initial loss modulus. At first sight our observations appear\nquantitatively consistent with a simple soft-glassy rheology (SGR)-type model,\nin which barrier crossings by mesoscopic elements are purely strain-induced.\nFor a given strain amplitude {\\gamma}0 each element can be classified as fluid\nor solid according to whether its local yield strain exceeds {\\gamma}0. Each\ncycle, the barrier heights E of yielded elements are reassigned according to a\nfixed prior distribution {\\rho}(E): this fixes the per-cycle probability\nR({\\gamma}0) of a fluid elements becoming solid. As the fraction of solid\nelements builds up, {\\gamma}0 falls (at constant stress amplitude), so\nR({\\gamma}0) increases. This positive feedback accounts for the sudden\nsolidification after a long delay. The model thus appears to directly link\nmacroscopic rheology with mesoscopic barrier height statistics: within its\nprecepts, our data point towards a power law for {\\rho}(E) rather than the\nexponential form usually assumed in SGR. However, despite this apparent\nsuccess, closer investigation shows that the assumptions of the model cannot be\nreconciled with the extremely large strain amplitudes arising in our\nexperiments. The quantitative explanation of delayed solidification in Laponite\ntherefore remains an open theoretical challenge."
    },
    {
        "anchor": "Induced Diffusion of Tracers in a Bacterial Suspension: Theory and\n  Experiments: The induced diffusion of tracers in a bacterial suspension is studied\ntheoretically and experimentally at low bacterial concentrations. Considering\nthe swimmer-tracer hydrodynamic interactions at low-Reynolds number and using a\nkinetic theory approach, it is shown that the induced diffusion coefficient is\nproportional to the swimmer concentration, their mean velocity and a\ncoefficient $\\beta$, as observed experimentally. The coefficient $\\beta$ scales\nas the tracer-swimmer cross section times the mean square displacement produced\nby single scatterings. The displacements depend on the swimmer propulsion\nforces. Considering simple swimmer models (acting on the fluid as two monopoles\nor as a force dipole) it is shown that $\\beta$ increases for decreasing\nswimming efficiencies. Close to solid surfaces the swimming efficiency degrades\nand, consequently, the induced diffusion increase. Experiments on W wild-type\n{\\em Escherichia coli} in a Hele-Shaw cell under buoyant conditions are\nperformed to measure the induced diffusion on tracers near surfaces. The\nmodification of the suspension pH vary the swimmers' velocity in a wide range\nallowing to extract the $\\beta$ coefficient with precision. It is found that\nthe solid surfaces modify the induced diffusion: decreasing the confinement\nheight of the cell, $\\beta$ increases by a factor 4. The theoretical model\nreproduces this increase although there are quantitative differences, probably\nattributed to the simplicity of the swimmer models.",
        "positive": "Jamming transition in emulsions and granular materials: We investigate the jamming transition in packings of emulsions and granular\nmaterials via molecular dynamics simulations. The emulsion model is composed of\nfrictionless droplets interacting via nonlinear normal forces obtained using\nexperimental data acquired by confocal microscopy of compressed emulsions\nsystems. Granular materials are modeled by Hertz-Mindlin deformable spherical\ngrains with Coulomb friction. In both cases, we find power-law scaling for the\nvanishing of pressure and excess number of contacts as the system approaches\nthe jamming transition from high volume fractions. We find that the\nconstruction history parametrized by the compression rate during the\npreparation protocol has a strong effect on the micromechanical properties of\ngranular materials but not on emulsions. This leads the granular system to jam\nat different volume fractions depending on the histories. Isostaticity is found\nin the packings close to the jamming transition in emulsions and in granular\nmaterials at slow compression rates and infinite friction. Heterogeneity of\ninterparticle forces increases as the packings approach the jamming transition\nwhich is demonstrated by the exponential tail in force distributions and the\nsmall values of the participation number measuring spatial localization of the\nforces. However, no signatures of the jamming transition are observed in\nstructural properties, like the radial distribution functions and the\ndistributions of contacts."
    },
    {
        "anchor": "Guiding self-assembly of active colloids by temporal modulation of\n  activity: Self-organization phenomena in ensembles of self-propelled particles open\npathways to the synthesis of new dynamic states not accessible by traditional\nequilibrium processes. The challenge is to develop a set of principles that\nfacilitate the control and manipulation of emergent active states. Here, we\nreport that dielectric rolling colloids energized by a pulsating electric field\nself-organize into alternating square lattices with a lattice constant\ncontrolled by the parameters of the field. We combine experiments and\nsimulations to examine spatiotemporal properties of the emergent collective\npatterns, and investigate the underlying dynamics of the self-organization.We\nreveal the resistance of the dynamic lattices to compression/expansion stresses\nleading to a hysteretic behavior of the lattice constant. The general mechanism\nof pattern synthesis and control in active ensembles via temporal modulation of\nactivity can be applied to other active colloidal systems.",
        "positive": "Electro-Optic Effects in Colloidal Dispersion of Metal Nano-Rods in\n  Dielectric Fluid: In modern transformation optics, one explores metamaterials with properties\nthat vary from point to point in space and time, suitable for applications in\ndevices such as an \"optical invisibility cloak\" and an \"optical black hole\". We\npropose an approach to construct spatially varying and switchable metamaterials\nthat are based on colloidal dispersions of metal nano-rods (NRs) in dielectric\nfluids, in which dielectrophoretic forces, originating in the electric field\ngradients, create spatially varying configurations of aligned NRs. The electric\nfield controls orientation and concentration of NRs and thus modulates the\noptical properties of the medium. Using gold (Au) NRs dispersed in toluene, we\ndemonstrate electrically induced change in refractive index on the order of\n0.1."
    },
    {
        "anchor": "Beyond Local Structures In Critical Supercooled Water Through\n  Unsupervised Learning: The presence of a second critical point in supercooled water as a scenario to\nexplain its anomalies has been a topic of intense investigation for the last\nfew decades. The molecular origins underlying this phenomenon are typically\nrationalized in terms of the competition between local high-density (HD) and\nlow-density (LD) structures. The physical realization of these local structures\noften requires the design of chemically inspired order parameters that are\ninevitably subject to human intervention. Herein, we use unsupervised learning\nto discover structures in atomistic simulations of liquid water close to its\nputative Liquid-Liquid Critical point (LLCP). Encoding the information of local\nenvironments using machine-learning inspired descriptors, we confirm the\npresence of large heterogeneity in local environments of the water molecules\nmasking a proper identification of LD and HD local configurations. Our agnostic\napproach shows the need to use non-local atomic structural descriptors that\ncharacterize important fluctuations on the nanometer length scale which\nultimately lead to the emergence of LD and HD domains rationalizing the\nmicroscopic origins of long-range density fluctuations close to criticality.",
        "positive": "Constraints and vibrations in static packings of ellipsoidal particles: We numerically investigate the mechanical properties of static packings of\nellipsoidal particles in 2D and 3D over a range of aspect ratio and compression\n$\\Delta \\phi$. While amorphous packings of spherical particles at jamming onset\n($\\Delta \\phi=0$) are isostatic and possess the minimum contact number $z_{\\rm\niso}$ required for them to be collectively jammed, amorphous packings of\nellipsoidal particles generally possess fewer contacts than expected for\ncollective jamming ($z < z_{\\rm iso}$) from naive counting arguments, which\nassume that all contacts give rise to linearly independent constraints on\ninterparticle separations. To understand this behavior, we decompose the\ndynamical matrix $M=H-S$ for static packings of ellipsoidal particles into two\nimportant components: the stiffness $H$ and stress $S$ matrices. We find that\nthe stiffness matrix possesses $N(z_{\\rm iso} - z)$ eigenmodes ${\\hat e}_0$\nwith zero eigenvalues even at finite compression, where $N$ is the number of\nparticles. In addition, these modes ${\\hat e}_0$ are nearly eigenvectors of the\ndynamical matrix with eigenvalues that scale as $\\Delta \\phi$, and thus finite\ncompression stabilizes packings of ellipsoidal particles. At jamming onset, the\nharmonic response of static packings of ellipsoidal particles vanishes, and the\ntotal potential energy scales as $\\delta^4$ for perturbations by amplitude\n$\\delta$ along these `quartic' modes, ${\\hat e}_0$. These findings illustrate\nthe significant differences between static packings of spherical and\nellipsoidal particles."
    },
    {
        "anchor": "Capillary-Gravity Waves on Depth-Dependent Currents: Consequences for\n  the Wave Resistance: We study theoretically the capillary-gravity waves created at the water-air\ninterface by a small two-dimensional perturbation when a depth-dependent\ncurrent is initially present in the fluid. Assuming linear wave theory, we\nderive a general expression of the wave resistance experienced by the\nperturbation as a function of the current profile in the case of an inviscid\nfluid. We then analyze and discuss in details the behavior of the wave\nresistance in the particular case of a linear current, a valid approximation\nfor some wind generated currents.",
        "positive": "Physical aging and relaxation of residual stresses in a colloidal glass\n  following flow cessation: Dilute Laponite suspensions in water at low salt concentration form repulsive\ncolloidal glasses which display physical aging. This phenomenon is still not\ncompletely understood and in particular, little is known about the connection\nbetween the flow history, as a determinant of the initial state of the system,\nand the subsequent aging dynamics. Using a stress controlled rheometer, we\nperform stress jump experiments to observe the elastic component of the flow\nstress that remains on cessation of flow or flow quenching. We investigate the\nconnection between the dynamics of these residual stresses and the rate of\nphysical aging upon quenching from different points on the steady state flow\ncurve. Quenching from high rates produces a fluid state, G\">G', with small,\nfast relaxing residual stresses and rapid, sigmoidal aging of the complex\nmodulus. Conversely, quenching from lower shear rates produces increasingly\njammed states featuring slowly relaxing stresses and a slow increase of the\ncomplex modulus with system age. Flow cessation from a fixed shear rate with\nvarying quench durations shows that slower quenches produce smaller residual\nstresses at short times which relax at long times by smaller extents, by\ncomparison with faster quenches. These smaller stresses are correlated with a\nhigher modulus but slower physical aging of the system. The characteristic time\nfor the residual stress relaxation scales inversely with the quench rate. This\nimplies a frustrated approach to any ideal stress-free state that succinctly\nreflects the frustrated nature of these glassy systems."
    },
    {
        "anchor": "Control of Noise in Chemical and Biochemical Information Processing: We review models and approaches for error-control in order to prevent the\nbuildup of noise when gates for digital chemical and biomolecular computing\nbased on (bio)chemical reaction processes are utilized to realize stable,\nscalable networks for information processing. Solvable rate-equation models\nillustrate several recently developed methodologies for gate-function\noptimization. We also survey future challenges and possible new research\navenues.",
        "positive": "Relation between Lacunarity, Correlation dimension and Euclidean\n  dimension of Systems: Lacunarity is a measure often used to quantify the lack of translational\ninvariance present in fractals and multifractal systems. The generalised\ndimensions, specially the first three, are also often used to describe various\naspects of mass distribution in such systems. In this work we establish that\nthe graph (\\textit{lacunarity curve}) depicting the variation of lacunarity\nwith scaling size, is non-linear in multifractal systems. We propose a\ngeneralised relation between the Euclidean dimension, the Correlation Dimension\nand the lacunarity of a system that lacks translational invariance, through the\nslope of the lacunarity curve. Starting from the basic definitions of these\nmeasures and using statistical mechanics, we track the standard algorithms- the\nbox counting algorithm for the determination of the generalised dimensions, and\nthe gliding box algorithm for lacunarity, to establish this relation. We go on\nto validate the relation on six systems, three of which are deterministically\ndetermined, while three others are real. Our examples span 2- and 3-\ndimensional systems, and euclidean, monofractal and multifractal geometries. We\nfirst determine the lacunarity of these systems using the gliding box\nalgorithm. In each of the six cases studied, the euclidean dimension, the\ncorrelation dimension in case of multifractals, and the lacunarity of the\nsystem, together, yield a value of the slope $S$ of the lacunarity curve at any\nlength scale. The predicted $S$ value matches the slope as determined from the\nactual plot of the lacunarity curves at the corresponding length scales. This\nestablishes that the relation holds for systems of any geometry or dimension."
    },
    {
        "anchor": "Viscosity measurements in pulsed magnetic fields by using a\n  quartz-crystal microbalance: Viscosity measurements in combination with pulsed magnetic fields are\ndeveloped by use of a quartz-crystal microbalance (QCM). When the QCM is\nimmersed in liquid, the resonant frequency, $f_0$, and the quality factor, $Q$,\nof the QCM change depending on $(\\rho\\eta)^{0.5}$, where $\\rho$ is the mass\ndensity and $\\eta$ the viscosity. During the magnetic-field pulse, $f_0$ and\n$Q$ of the QCM are simultaneously measured by a ringdown technique. The typical\nresolution of $(\\rho\\eta)^{0.5}$ is 0.5 %. As a benchmark, the viscosity of\nliquid oxygen is measured up to 55 T.",
        "positive": "Fluctuations of Single Confined Actin Filaments: This paper withdrawn since it has been published in an updated version in\nBiophysical Reviews and Letter Vol. 2, No. 2 (2007) 155-166"
    },
    {
        "anchor": "Electromagnetic-radiation absorption of water: Why does a microwave oven work? How does biological tissue absorb\nelectromagnetic radiation? Astonishingly, we do not have a definite answer to\nthese simple questions because the microscopic processes governing the\nabsorption of electromagnetic waves by water are largely unclarified. This\nabsorption can be quantified by dielectric loss spectra, which reveal a huge\npeak at a frequency of the exciting electric field of about 20 GHz and a\ngradual tailing off towards higher frequencies. The microscopic interpretation\nof such spectra is highly controversial and various superpositions of\nrelaxation and resonance processes ascribed to single-molecule or\nmolecule-cluster motions have been proposed for their analysis. By combining\ndielectric, microwave, THz, and far-infrared spectroscopy, here we provide\nnearly continuous temperature-dependent broadband spectra of water. Moreover,\nwe find that corresponding spectra for aqueous solutions reveal the same\nfeatures as pure water. However, in contrast to the latter, crystallization in\nthese solutions can be avoided by supercooling. As different spectral\ncontributions tend to disentangle at low temperatures, this enables to\ndeconvolute them when approaching the glass transition under cooling. We find\nthat the overall spectral development, including the 20 GHz feature (employed\nfor microwave heating), closely resembles the behavior known for common\nsupercooled liquids. Thus, water's absorption of electromagnetic waves at room\ntemperature is not unusual but very similar to that of glass-forming liquids at\nelevated temperatures, deep in the low-viscosity liquid regime, and should be\ninterpreted along similar lines.",
        "positive": "Structure in Sheared Supercooled Liquids: Dynamical Rearrangements of an\n  Effective System of Icosahedra: We consider a binary Lennard-Jones glassformer whose super-Arrhenius dynamics\nare correlated with the formation of particles organized into icosahedra under\nsimple steady state shear. We recast this glassformer as an effective system of\nicosahedra [Pinney et al. J. Chem. Phys. 143 244507 (2015)]. From the observed\npopulation of icosahedra in each steady state, we obtain an effective\ntemperature which is linearly dependent on the shear rate in the range\nconsidered. Upon shear banding, the system separates into a region of high\nshear rate and a region of low shear rate. The effective temperatures obtained\nin each case show that the low shear regions correspond to a significantly\nlower temperature than the high shear regions. Taking a weighted average of the\neffective temperature of these regions (weight determined by region size)\nyields an estimate of the effective temperature which compares well with an\neffective temperature based on the global mesocluster population of the whole\nsystem."
    },
    {
        "anchor": "Foamability of aqueous solutions: Role of surfactant type and\n  concentration: In this paper we study the main surface characteristics which control the\nfoamability of solutions of various surfactants. Experiments with anionic,\ncationic and nonionic surfactants with different head groups and chain lengths\nare performed in a wide concentration range, from 0.001 mM to 100 mM. The\nelectrolyte concentration is also varied from 0 up to 100 mM. For all\nsurfactants studied, three regions in the dependence of the foamability, VA, on\nthe logarithm of surfactant concentration, lgCS, are observed. In Region 1, VA\nis very low and depends weakly on CS. In Region 2, VA increases steeply with\nCS. In Region 3, VA reaches a plateau. A key new element in our interpretation\nof the foaming data is that we use the surface tension measurements to\ndetermine the dependence of the main surface properties (surfactant adsorption,\nsurface coverage and surface elasticity) on the surface age of the bubbles. In\nthis way we interpret the results from the foaming tests by considering the\nproperties of the dynamic adsorption layers, formed during foaming. The data\nfor the nonionic and ionic surfactants merge around two master curves when\nplotted as a function of the surface coverage, the surface mobility factor, or\nthe Gibbs elasticity of the dynamic adsorption layers. This difference between\nthe ionic and nonionic surfactants is explained with the important contribution\nof the electrostatic repulsion between the foam film surfaces for the ionic\nsurfactants which stabilizes the dynamic foam films even at moderate surface\ncoverage and at relatively high ionic strength. In contrast, the films formed\nfrom solutions of nonionic surfactants are stabilized via steric repulsion\nwhich becomes sufficiently high to prevent bubble coalescence only at rather\nhigh surface coverage (> 90 %) which corresponds to related high Gibbs\nelasticity (> 150 mN/m) and low surface mobility of the dynamic adsorption\nlayers.",
        "positive": "Interplay Between Time-Temperature-Transformation and the Liquid-Liquid\n  Phase Transition in Water: We study the TIP5P water model proposed by Mahoney and Jorgensen, which is\ncloser to real water than previously-proposed classical pairwise additive\npotentials. We simulate the model in a wide range of deeply supercooled states\nand find (i) the existence of a non-monotonic ``nose-shaped'' temperature of\nmaximum density line and a non-reentrant spinodal, (ii) the presence of a low\ntemperature phase transition, (iii) the free evolution of bulk water to ice,\nand (iv) the time-temperature-transformation curves at different densities."
    },
    {
        "anchor": "Harmonic Order Parameters for Characterizing Complex Particle\n  Morphologies: Order parameters based on spherical harmonics and Fourier coefficients\nalready play a significant role in condensed matter research in the context of\nsystems of spherical or point particles. Here, we extend these types of order\nparameter to more complex shapes, such as those encountered in nanoscale\nself-assembly applications. To do so, we build on a powerful set of techniques\nthat originate in the computer science field of \"shape matching.\" We\ndemonstrate how shape matching techniques can be applied to identify unknown\nstructures and create highly-specialized \\textit{ad hoc} order parameters.\nAdditionally, we investigate the special symmetry properties of harmonic\ndescriptors, and demonstrate how they can be exploited to provide optimal\nsolutions to certain classes of problems. Our techniques can be applied to\nparticle systems in general, both simulated and experimental, provided the\nparticle positions are known.",
        "positive": "Hot Particles Attract in a Cold Bath: Controlling interactions out of thermodynamic equilibrium is crucial for\ndesigning addressable and functional self-organizing structures. These active\ninteractions also underpin collective behavior in biological systems. Here we\nstudy a general setting of active particles in a bath of passive particles, and\ndemonstrate a novel mechanism for long range attraction between active\nparticles. The mechanism operates when the translational persistence length of\nthe active particle motion is smaller than the particle diameter. In this\nlimit, the system reduces to particles of higher diffusivity (\"hot\" particles)\nin a bath of particles with lower diffusivity (\"cold\" particles). This\nattractive interaction arises as a hot particle pushes cold particles away to\ncreate a large hole around itself, and the holes interact via a depletion-like\nattraction. Strikingly, the interaction range is more than an order of\nmagnitude larger than the particle radius, well beyond the range of\nconventional depletion force. Although the mechanism occurs outside the\nparameter regime of typical biological swimmers, the mechanism could be\nrealized in the laboratory."
    },
    {
        "anchor": "Chromatin: a tunable spring at work inside chromosomes: This paper focuses on mechanical aspects of chromatin biological functioning.\nWithin a basic geometric modeling of the chromatin assembly, we give for the\nfirst time the complete set of elastic constants (twist and bend persistence\nlengths, stretch modulus and twist-stretch coupling constant) of the so-called\n30-nm chromatin fiber, in terms of DNA elastic properties and geometric\nproperties of the fiber assembly. The computation naturally embeds the fiber\nwithin a current analytical model known as the ``extensible worm-like rope'',\nallowing a straightforward prediction of the force-extension curves. We show\nthat these elastic constants are strongly sensitive to the linker length, up to\n1 bp, or equivalently to its twist, and might locally reach very low values,\nyielding a highly flexible and extensible domain in the fiber. In particular,\nthe twist-stretch coupling constant, reflecting the chirality of the chromatin\nfiber, exhibits steep variations and sign changes when the linker length is\nvaried.\n  We argue that this tunable elasticity might be a key feature for chromatin\nfunction, for instance in the initiation and regulation of transcription.",
        "positive": "Simple Fluids with Complex Phase Behavior: We find that a system of particles interacting through a simple isotropic\npotential with a softened core is able to exhibit a rich phase behavior\nincluding: a liquid-liquid phase transition in the supercooled phase, as has\nbeen suggested for water; a gas-liquid-liquid triple point; a freezing line\nwith anomalous reentrant behavior. The essential ingredient leading to these\nfeatures resides in that the potential investigated gives origin to two\neffective core radii."
    },
    {
        "anchor": "A jamming plane of sphere packings: The concept of jamming has attracted great research interest due to its broad\nrelevance in soft matter such as liquids, glasses, colloids, foams, and\ngranular materials, and its deep connection to the sphere packing problem and\noptimization problems. Here we show that the domain of amorphous jammed states\nof frictionless spheres can be significantly extended, from the well-known\njamming-point at a fixed density, to a jamming-plane that spans the density and\nshear strain axes. We explore the jamming-plane, via athermal and thermal\nsimulations of compression and shear jamming, with a help of an efficient swap\nalgorithm to prepare initial equilibrium configurations. The jamming-plane can\nbe divided into reversible-jamming and irreversible-jamming regimes, based on\nthe reversibility of the route from the initial configuration to jamming. Our\nresults suggest that the irreversible-jamming behavior reflects an escape from\nthe meta-stable glass basin to which the initial configuration belongs to, or\nthe absence of such basins. All jammed states, either compression or shear\njammed, are isostatic, and exhibit jamming criticality of the same universality\nclass. However, the anisotropy of contact networks non-trivially depends on the\njamming density and strain. Among all state points on the jamming-plane, the\njamming-point is a unique one with the minimum jamming density and the maximum\nrandomness. For lattice packings, the jamming-plane shrinks into a single shear\njamming-line that is independent of initial configurations. Our study paves the\nway for solving the long-standing random close packing problem, and provides a\nmore complete framework to understand jamming.",
        "positive": "Comparison of Field Theory Models of Interest Rates with Market Data: We calibrate and test various variants of field theory models of the interest\nrate with data from eurodollars futures. A model based on a simple\npsychological factor are seen to provide the best fit to the market. We make a\nmodel independent determination of the volatility function of the forward rates\nfrom market data."
    },
    {
        "anchor": "Breaking the Reptation Trap: Escape Dynamics of Semi-Flexible Polymers\n  in Crowded Networks: Semi-flexible polymers in crowded environments exhibit complex dynamics that\nplay a crucial role in various biological and material design processes. Based\non the classic reptation theory, it is generally believed that semiflexible\npolymers are trapped within static confinements. Here we demonstrate that\nsemi-flexible polymers are indeed trapped in short-lived kinetic cages. We have\ndeveloped a novel scaling law for rotational diffusion through the examination\nof the polymer network at the level of an individual nanofiber and quantify the\nonset of entanglement and entanglement itself by introducing an effective tube\ndiameter. We also show that understanding these dynamics is critical for\ninterpreting the macroscopic behavior of such systems, as evidenced by our\nmicro-rheology analysis. The insight from our study provides a rectified\nmicroscopic understanding of the dynamics of semi-flexible polymers in complex\nenvironments, yielding new principles to better understand the macroscopic\nbehavior of crowded systems, from biophysics to materials science.",
        "positive": "Paradoxical Coffee-Stain Effect Driven by the Marangoni Flow Observed on\n  Oil-Infused Surfaces: Formation of coffee stain deposits under evaporation of droplets containing\naqueous solution of salts placed on silicone-oil impregnated substrates was\nobserved. The formation of ring-like deposits was registered for various molar\nconcentrations of salts for the droplets of 5-300 microlitres in volume. The\neffect occurred when the contact line was de-pinned, and the evaporation from\nthe edge of a droplet was stopped by the silicone oil. The formation of the\ncoffee stain deposit is related to the soluto-capillary Marangoni flow; the\ninfluence of the thermo-capillary flow taking place in parallel is negligible."
    },
    {
        "anchor": "Local Interactions and Protein Folding: A Model Study on the Square and\n  Triangular Lattices: We study a simple heteropolymer model containing sequence-independent local\ninteractions on both square and triangular lattices. Sticking to a two-letter\ncode, we investigate the model for varying strength $\\kappa$ of the local\ninteractions; $\\kappa=0$ corresponds to the well-known HP model [K.F. Lau and\nK.A. Dill, Macromolecules 22, 3986 (1989)]. By exhaustive enumerations for\nshort chains, we obtain all structures which act as a unique and pronounced\nenergy minimum for at least one sequence. We find that the number of such\ndesignable structures depends strongly on $\\kappa$. Also, we find that the\nnumber of designable structures can differ widely for the two lattices at a\ngiven $\\kappa$. This is the case, for example, at $\\kappa=0$, which implies\nthat the HP model exhibits different behavior on the two lattices. Our findings\nclearly show that sequence-independent local properties of the chains can play\nan important role in the formation of unique minimum energy structures.",
        "positive": "Layering transitions of the spin-1/2 Ising model in a transverse\n  magnetic field: Using mean field theory, the effect of the transverse magnetic field on the\nlayering and wetting transitions of the spin-1/2 Ising model with longitudinal\nmagnetic field is studied. At a fixed value of the temperature smaller than the\nwetting temperature, such system exibits a sequence of layering transitions\nabove a critical value of the transverse magnetic field, wich depends on the\ntemperature and surface magnetic field."
    },
    {
        "anchor": "Dynamics of Strongly Deformed Polymers in Solution: Bead spring models for polymers in solution are nonlinear if either the\nfinite extensibility of the polymer, excluded volume effects or hydrodynamic\ninteractions between polymer segments are taken into account. For such models\nwe use a powerful method for the determination of the complete relaxation\nspectrum of fluctuations at {\\it steady state}. In general, the spectrum and\nmodes differ significantly from those of the linear Rouse model. For a tethered\npolymer in uniform flow the differences are mainly caused by an inhomogeneous\ndistribution of tension along the chain and are most pronounced due to the\nfinite chain extensibility. Beyond the dynamics of steady state fluctuations we\nalso investigate the nonlinear response of the polymer to a {\\em large sudden\nchange} in the flow. This response exhibits several distinct regimes with\ncharacteristic decay laws and shows features which are beyond the scope of\nsingle mode theories such as the dumbbell model.",
        "positive": "Viscous droplet impingement on soft substrates: Viscous droplets impinging on soft substrates may exhibit several distinct\nbehaviours including repeated bouncing, wetting, and hovering, i.e., spreading\nand retracting after impact without bouncing back or wetting. We experimentally\nstudy the conditions enabling these characteristic behaviours by systematically\nvarying the substrate elasticity, impact velocity and the liquid viscosity. For\neach substrate elasticity, the transition to wetting is determined as the\ndependence of the Weber number We, which measures the droplet's kinetic energy\nagainst its surface energy, on the Ohnesorge number Oh, which compares\nviscosity to inertia and capillarity. We find that while We at the wetting\ntransition monotonically decreases with Oh for relatively rigid substrates, it\nexhibits a counter-intuitive behaviour in which it first increases then\ngradually decreases for softer substrates. We experimentally determine the\ndependence of the maximum Weber number allowing non-wetting impacts on the\nsubstrate elasticity and show that it provides an excellent quantitative\nmeasure of liquid repellency for a wide range of surfaces, from liquid to soft\nsurfaces and non-deformable surfaces."
    },
    {
        "anchor": "Ground states of colloidal molecular crystals on periodic substrates: Two dimensional suspensions of spherical colloids subject to periodic\nexternal fields exhibit a rich variety of molecular crystalline phases. We\nstudy in simulations the ground state configurations of dimeric and trimeric\nsystems, that are realized on square and triangular lattices, when either two\nor three macroions are trapped in each external potential minimum. Bipartite\norders of the checkerboard or stripe types are reported together with more\ncomplex quadripartite orderings, and the shortcomings of envisioning the\ncolloids gathered in a single potential minimum as a composite rigid object are\ndiscussed. This work also sheds light on simplifying assumptions underlying\nprevious theoretical treatments and that made possible the mapping onto spin\nmodels.",
        "positive": "Multiple scattering suppression in dynamic light scattering based on a\n  digital camera detection scheme: We introduce a charge coupled device (CCD) camera based detection scheme in\ndynamic light scattering that provides information on the single-scattered\nauto-correlation function even for fairly turbid samples. It is based on the\nsingle focused laser beam geometry combined with the selective cross\ncorrelation analysis of the scattered light intensity. Using a CCD camera as a\nmultispeckle detector we show how spatial correlations in the intensity pattern\ncan be linked to single and multiple scattering processes. Multiple scattering\nsuppression is then achieved by an efficient cross correlation algorithm\nworking in real time with a temporal resolution down to 0.2 seconds. Our\napproach allows access to the extensive range of systems that show low-order\nscattering by selective detection of the singly scattered light. Model\nexperiments on slowly relaxing suspensions of titanium dioxide in glycerol were\ncarried out to establish the validity range of our approach. Successful\napplication of the method is demonstrated up to a scattering coefficient of\nmore than $\\mu_s = 5$ cm$^{-1}$ for the sample size of L=1 cm."
    },
    {
        "anchor": "Numerical studies of aerofractures in porous media / Estudios numericos\n  de aerofractures en medios porosos: During the hydraulically induced compaction of a granular layer fracture\npatterns arise. In numerical simulations we study how these patterns depend on\nthe gas properties as well as on the properties of the porous medium. In\nparticular the relation between the speed of fracture propagation and injection\npressure is here studied in detail.",
        "positive": "Large effect of polydispersity on defect concentrations in colloidal\n  crystals: We compute the equilibrium concentration of stacking faults and point defects\nin polydisperse hard-sphere crystals. We find that, while the concentration of\nstacking faults remains similar to that of monodisperse hard sphere crystals,\nthe concentration of vacancies decreases by about a factor two. Most\nstrikingly, the concentration of interstitials in the maximally polydisperse\ncrystal may be some six orders of magnitude larger than in a monodisperse\ncrystal. We show that this dramatic increase in interstitial concentration is\ndue to the increased probability of finding small particles and that the\nsmall-particle tail of the particle size distribution is crucial for the\ninterstitial concentration in a colloidal crystal."
    },
    {
        "anchor": "Core-softened Fluids, Water-like Anomalies and the Liquid-Liquid\n  Critical Points: Molecular dynamics simulations are used to examine the relationship between\nwater-like anomalies and the liquid-liquid critical point in a family of model\nfluids with multi-Gaussian, core-softened pair interactions. The core-softened\npair interactions have two length scales, such that the longer length scale\nassociated with a shallow, attractive well is kept constant while the shorter\nlength scale associated with the repulsive shoulder is varied from an inflexion\npoint to a minimum of progressively increasing depth.\n  As the shoulder well depth increases, the pressure required to form the high\ndensity liquid decreases and the temperature up to which the high-density\nliquid is stable increases, resulting in the shift of the liquid-liquid\ncritical point to much lower pressures and higher temperatures. The pair\ncorrelation entropy is computed to show that the excess entropy anomaly\ndiminishes when the shoulder well depth increases. Excess entropy scaling of\ndiffusivity in this class of fluids is demonstrated, showing that decreasing\nstrength of the excess entropy anomaly with increasing shoulder depth results\nin the progressive loss of water-like thermodynamic, structural and transport\nanomalies. Instantaneous normal mode analysis was used to index the overall\ncurvature distribution of the fluid and the fraction of imaginary frequency\nmodes was shown to correlate well with the anomalous behaviour of the\ndiffusivity and the pair correlation entropy. The results suggest in the case\nof core-softened potentials, in addition to the presence of two length scales,\nenergetic and entropic effects associated with local minima and curvatures of\nthe pair interaction play an important role in determining the presence of\nwater-like anomalies and the liquid-liquid phase transition.",
        "positive": "Conformational statistics of randomly-branching double-folded ring\n  polymers: The conformations of topologically constrained double-folded ring polymers\ncan be described as wrappings of randomly branched primitive trees. We extend\nprevious work on the tree statistics under different (solvent) conditions to\nexplore the conformational statistics of double-folded rings in the limit of\ntight wrapping. In particular, we relate the exponents characterizing the ring\nstatistics to those describing the primitive trees and discuss the distribution\nfunctions $p(\\vec r | \\ell)$ and $p(L | \\ell)$ for the spatial distance, $\\vec\nr$, and tree contour distance, $L$, between monomers as a function of their\nring contour distance, $\\ell$."
    },
    {
        "anchor": "Investigation of the dynamical slowing down process in soft glassy\n  colloidal suspensions: comparisons with supercooled liquids: The primary and secondary relaxation timescales of aging colloidal\nsuspensions of Laponite are estimated from intensity autocorrelation functions\nobtained in dynamic light scattering (DLS) experiments. The dynamical slowing\ndown of these relaxation processes are compared with observations in fragile\nsupercooled liquids by establishing a one-to-one mapping between the waiting\ntime since filtration of a Laponite suspension and the inverse of the\ntemperature of a supercooled liquid that is rapidly quenched towards its glass\ntransition temperature. New timescales, such as the Vogel time and the Kauzmann\ntime, are extracted to describe the phenomenon of dynamical arrest in Laponite\nsuspensions. In results that are strongly reminiscent of those extracted from\nsupercooled liquids approaching their glass transitions, it is demonstrated\nthat the Vogel time calculated for each Laponite concentration is approximately\nequal to the Kauzmann time, and that a strong coupling exists between the\nprimary and secondary relaxation processes of aging Laponite suspensions.\nFurthermore, the experimental data presented here clearly demonstrates the\nself-similar nature of the aging dynamics of Laponite suspensions within a\nrange of sample concentrations.",
        "positive": "p=constant compression on loose Hostun sand: The case of an anisotropic\n  response: Experimental data from axially symmetric compression test at constant mean\npressure p on Hostun sand from Flavigny experiments on loose sands are used to\nstudy the validity of an \"isotropic\" modelling at different densities . It is\nfound that the material response is not isotropic even at small deviatoric\nstress. As an \"isotropic\" behaviour is found for compression test at constant\nvolume on the same sand, this new result questions the unicity of the\ntrajectory in the classical phase space of soil mechanics (q,p,v), with q being\nthed deviatoric stress, v the specific volume. This asks whether the space\nshall be taken larger than 3d or not. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn"
    },
    {
        "anchor": "Hydrodynamic fluctuations of a liquid with anisotropic molecules: A general theory of hydrodynamic fluctuations of a liquid with anisotropic\nmolecules, in the presence of steady simple shear, has been proposed.",
        "positive": "Revisiting the entropic force between fluctuating biological membranes: The complex interplay between the various attractive and repulsive forces\nthat mediate between biological membranes governs an astounding array of\nbiological functions: cell adhesion, membrane fusion, self-assembly,\nbinding-unbinding transition among others. In this work, the entropic repulsive\nforce between membranes---which originates due to thermally excited\nfluctuations---is critically reexamined both analytically and through\nsystematic Monte Carlo simulations. A recent work by Freund \\cite {Freund13}\nhas questioned the validity of a well-accepted result derived by Helfrich\n\\cite{Helfrich78}. We find that, in agreement with Freund, for small\ninter-membrane separations ($d$), the entropic pressure scales as $p\\sim 1/d $,\nin contrast to Helfrich's result: $p\\sim 1/d^3$. For intermediate separations,\nour calculations agree with that of Helfrich and finally, for large\ninter-membrane separations, we observe an exponentially decaying behavior."
    },
    {
        "anchor": "Stability Against the Odds: the Case of Chromonic Liquid Crystals: The ground state of chromonic liquid crystals, as revealed by a number of\nrecent experiments, is quite different from that of ordinary nematic liquid\ncrystals: it is twisted instead of uniform. The common explanation provided for\nthis state within the classical elastic theory of Frank demands that one\nEricksen's inequality is violated. Since in general such a violation makes\nFrank's elastic free-energy functional unbounded below, the question arises as\nto whether the twisted ground state can be locally stable. We answer this\nquestion in the affirmative. In reaching this conclusion, a central role is\nplayed by the specific boundary conditions imposed in the experiments on the\nboundary of rigid containers and by a general formula that we derive here for\nthe second variation of Frank's elastic free energy.",
        "positive": "Topology of atomically thin soft ferroelectric membranes at finite\n  temperature: One account of two-dimensional (2D) structural transformations in 2D\nferroelectrics predicts an evolution from a structure with Pnm2$_1$ symmetry\ninto a structure with square P4/nmm symmetry and is consistent with\nexperimental evidence, while another argues for a transformation into a\nstructure with rectangular Pnmm symmetry. An analysis of the assumptions made\nin these models is provided here, and six fundamental results concerning these\ntransformations are contributed as follows: (i) Softened phonon modes produce\nrotational modes in these materials. (ii) The transformation to a structure\nwith P4/nmm symmetry occurs at the lowest critical temperature $T_c$. (iii) The\nhypothesis that one unidirectional optical vibrational mode underpins the 2D\ntransformation is unwarranted. (iv) Being successively more constrained, a\nsuccession of critical temperatures ($T_c<T_c'<T_c''$) occurs in going from\nmolecular dynamics calculations with the NPT and NVT ensembles onto the model\nwith unidirectional oscillations. (v) The choice of exchange-correlation\nfunctional impacts the estimate of the critical temperature. (vi) Crucially,\nthe correct physical picture of these transformations is one in which\nrotational modes confer a topological character to the 2D transformation via\nthe proliferation of vortices."
    },
    {
        "anchor": "Deformable active nematic particles and emerging edge currents in\n  circular confinements: We consider a microscopic field theoretical approach for interacting active\nnematic particles. With only steric interactions the self-propulsion strength\nin such systems can lead to different collective behaviour, e.g., synchronized\nself-spinning and collective translation. The different behaviour results from\nthe delicate interplay between internal nematic structure, particle shape\ndeformation and particle-particle interaction. For intermediate active strength\nan asymmetric shape emerges and leads to chirality and self-spinning crystals.\nFor larger active strength the shape is symmetric and translational collective\nmotion emerges. Within circular confinements, depending on the packing\nfraction, the self-spinning regime either stabilizes positional and\norientational order or can lead to edge currents and global rotation which\ndestroys the synchronized self-spinning crystalline structure.",
        "positive": "Stability of adhesion clusters under constant force: We solve the stochastic equations for a cluster of parallel bonds with shared\nconstant loading, rebinding and the completely dissociated state as an\nabsorbing boundary. In the small force regime, cluster lifetime grows only\nlogarithmically with bond number for weak rebinding, but exponentially for\nstrong rebinding. Therefore rebinding is essential to ensure physiological\nlifetimes. The number of bonds decays exponentially with time for most cases,\nbut in the intermediate force regime, a small increase in loading can lead to\nmuch faster decay. This effect might be used by cell-matrix adhesions to induce\nsignaling events through cytoskeletal loading."
    },
    {
        "anchor": "Dynamics of a spherical self-propelled tracer in a polymeric medium:\n  interplay of self-propulsion, stickiness, and crowding: We employ computer simulations to study the dynamics of a self-propelled\nspherical tracer particle in a viscoelastic medium, made of a long polymer\nchain. Here, the interplay between viscoelasticity, stickiness, and activity\n(self-propulsion) brings additional complexity to the tracer dynamics. Our\nsimulation shows that on increasing the stickiness of the tracer particle to\nthe polymer beads, the dynamics of the tracer particle slows down as it gets\nstuck to the polymer chain, and moves along with it. But with increasing the\nself-propulsion velocity, the dynamics gets enhanced. In case of increasing\nstickiness as well as activity, the non-Gaussian parameter (NGP) exhibits\nnon-monotonic behavior, which also shows up in the re-scaled self part of the\nvan-Hove function. Non-Gaussianity results owing to the enhanced binding\nevents, and the sticky motion of the tracer along with the chain with\nincreasing stickiness. On the other hand, with increasing activity, initially\nnon-Gaussianity increases as the tracer moves through the heterogenous\npolymeric environment but for higher activity, escapes resulting negative NGP.\nFor higher values of stickiness, the trapping time distributions of the passive\ntracer particle broadens and have long tails. On the other hand, for a given\nstickiness with increasing self-propulsion force, the same becomes narrower and\nhave short tails. We believe that our current simulation study will be helpful\nin elucidating the complex motion of activity-driven probes in viscoelastic\nmedia.",
        "positive": "Semiflexible Polymer Dynamics with a Bead-Spring Model: We study the dynamical properties of semiflexible polymers with a recently\nintroduced bead-spring model. We focus on double-stranded DNA. The two\nparameters of the model, $T^*$ and $\\nu$, are chosen to match its experimental\nforce-extension curve. The bead-spring Hamiltonian is approximated in the first\norder by the Hessian that is quadratic in the bead positions. The eigenmodels\nof the Hessian provide the longitudinal (stretching) and transverse (bending)\neigenmodes of the polymer, and the corresponding eigenvalues match well with\nthe established phenomenology of semiflexible polymers. Using the longitudinal\nand transverse eigenmodes, we obtain analytical expressions of (i) the\nautocorrelation function of the end-to-end vector, (ii) the autocorrelation\nfunction of a bond (i.e., a spring, or a tangent) vector at the middle of the\nchain, and (iii) the mean-square displacement of a tagged bead in the middle of\nthe chain, as sum over the contributions from the modes. We also perform\nsimulations with the full dynamics of the model. The simulations yield\nnumerical values of the correlation functions (i-iii) that agree very well with\nthe analytical expressions for the linearized dynamics. We also study the\nmean-square displacement of the longitudinal component of the end-to-end vector\nthat showcases strong nonlinear effects in the polymer dynamics, and we\nidentify at least an effective $t^{7/8}$ power-law regime in its\ntime-dependence. Nevertheless, in comparison to the full mean-square\ndisplacement of the end-to-end vector the nonlinear effects remain small at all\ntimes --- it is in this sense we state that our results demonstrate that the\nlinearized dynamics suffices for dsDNA fragments that are shorter than or\ncomparable to the persistence length. Our results are consistent with those of\nthe wormlike chain (WLC) model, the commonly used descriptive tool of\nsemiflexible polymers."
    },
    {
        "anchor": "Size Dependent Phase Transitions: The contributions of heat and work in generating a new surface area are\nconsidered. Unlike the classical theory of vapor/droplet equilibrium, which\nassociates changing surface areas with work done against the surface tension,\nan alternative approach assumes that the droplets grow due to a controllable\ncondensation of vapor and the internal energy of droplets changes due to the\nheat of the phase transition, and not due to the mechanical work. The effect of\nradii on the internal energy is discussed. The theory of the vapor/droplet\nequilibrium is constructed on the basis of the fundamental Clapeyron equation.\nWhen droplet radii exceed about 50 Lennard-Jones' molecular diameters, the\nclassical and new models yield similar values of thermodynamic parameters, but\ndiffer essentially in the range of the finest clusters and nanocapillaries. In\ncontrast to the Kelvin equation, which is not applicable for adsorption in\nmicropores with radii less than 1 nm and fails in its description of hysteresis\nloops in mesopores, the present approach is in reasonably good agreement with\nobservations; the model gives rational explanations to the mechanism of a\ndroplet growth and critical parameters of nucleation.",
        "positive": "Non reciprocal odd viscosity: Coarse graining the kinetic energy and\n  exceptional instability: Odd viscosity couples stress to strain rate in a dissipationless way. It has\nbeen studied in plasmas under magnetic fields, superfluid ${\\rm He}^3$, quantum\nHall fluids, and recently in the context of chiral active matter. In most of\nthese studies odd terms in the viscosity obey Onsager reciprocal relations.\nAlthough this is expected in equilibrium systems, it is not obvious that\nOnsager relations hold in active materials. By directly coarse graining the\nkinetic energy and using both the Poisson-bracket formalism and a kinetic\ntheory derivation, we find that the appearance of a non-vanishing angular\nmomentum density necessarily breaks Onsager reciprocal relations, which leads\nto a non-Hermitian dynamical matrix for the total momentum and to the\nappearance of odd viscosity and other non-dissipative contributions to the\nviscosity. Furthermore, by accounting for both the angular momentum density and\ninteractions that lead to odd viscosity, we find regions in the parameter space\nin which 3D odd mechanical waves propagate and and regions in which they are\nmechanically unstable. The lines separating these regions are continuous lines\nof exceptional points, suggesting of a non-reciprocal phase transition."
    },
    {
        "anchor": "Equivalence between condensation and boiling in a Lennard Jones fluid: Condensation and boiling are phase transitions highly relevant to industry,\ngeology or atmospheric science. These phase transitions are initiated by the\nnucleation of a drop in a supersaturated vapor and of a bubble in an\noverstretched liquid respectively. The surface tension between both phases,\nliquid and vapor, is a key parameter in the development of such nucleation\nstage. Whereas the surface tension can be readily measured for a flat\ninterface, there are technical and conceptual limitations to obtain it for the\ncurved interface of the nucleus. On the technical side, it is quite difficult\nto observe a critical nucleus in experiments. From a conceptual point of view,\nthe interfacial free energy depends on the choice of the dividing surface,\nbeing the surface of tension the one relevant for nucleation. We bypass the\ntechnical limitation by performing simulations of a Lennard Jones fluid where\nwe equilibrate critical nuclei (both drops and bubbles). Regarding the\nconceptual hurdle, we find the relevant cluster size by searching the radius\nthat correctly predicts nucleation rates and nucleation free energy barriers\nwhen combined with Classical Nucleation Theory. With such definition of the\ncluster size we find the same value of the surface tension for drops and\nbubbles of a given radius. Thus, condensation and boiling can be viewed as two\nsides of the same coin. Finally, we combine the data coming from drops and\nbubbles to obtain, via two different routes, estimates of the Tolman length, a\nparameter that allows describing the curvature dependence of the surface\ntension in a theoretical framework.",
        "positive": "Multiple-relaxation-time Finsler-Lagrange dynamics in a compressed\n  Langmuir monolayer: In this paper an information geometric approach has been proposed to describe\nthe two-dimensional (2d) phase transition of the first order in a monomolecular\nlayer (monolayer) of amphiphilic molecules deposited on air/water interface.\nThe structurization of the monolayer was simulated as an entropy evolution of a\nstatistical set of microscopic states with a large number of relaxation times.\nThe electrocapillary forces are considered as information constraints on the\nstatistical manifold. The solution curves of Euler-Lagrange equations and the\nJacobi field equations point out contracting pencils of geodesic trajectories\non the statistical manifold, which may change into spreading ones, and\nconverse. It was shown that the information geometrodynamics of the first-order\nphase transition in the Langmuir monolayer finds an appropriate realization\nwithin the Finsler-Lagrange framework."
    },
    {
        "anchor": "Nematics, Knots and Non-orientable Surfaces: Knots and knotted fields enrich physical phenomena ranging from DNA and\nmolecular chemistry to the vortices of fluid flows and textures of ordered\nmedia. Liquid crystals provide an ideal setting for exploring such topological\nphenomena through control of their characteristic defects. The use of colloids\nin generating defects and knotted configurations in liquid crystals has been\ndemonstrated for spherical and toroidal particles and shows promise for the\ndevelopment of novel photonic devices. Extending this existing work, we\ndescribe the full topological implications of colloids representing\nnon-orientable surfaces and use it to construct torus knots and links of type\n($p$,2) around multiply-twisted M\\\"obius strips.",
        "positive": "Biaxial nematics with C2h symmetry composed of calamitic particles. A\n  molecular field theory: A molecular field theory of biaxial nematics formed by molecules with C2h\npoint group symmetry has been developed by Luckhurst et al. and a Monte Carlo\ncomputer simulation study of this model has been performed by Hashim et al.. In\nthese studies the truncated model pair potential was only applied to molecules\nwhose long axes are taken to be along their C2 rotation axes. The present study\nextends this work by assuming that the molecular long axis is now perpendicular\nto the C2 axis, resulting in there being two possible choices of minor axes. It\nconsiders the phases formed by both cases. The molecular field theory for these\nmodels is formulated and reported here. The theoretical treatment of the\npresent cases gives rise to a new set of order parameters. So as to simplify\nthe pseudo-potentials only the dominant second rank order parameters are\nconsidered and evaluated to give the phase behaviour of these truncated models.\nThe predicted phase behaviour is compared with the results from the molecular\nfield study of the previous model potential."
    },
    {
        "anchor": "Scale-dependent elasticity as a probe of universal heterogeneity in\n  equilibrium amorphous solids: The equilibrium amorphous solid state -- formed, e.g., by adequately randomly\ncrosslinking the constituents of a macromolecular fluid -- is a heterogeneous\nstate characterized by a universal distribution of particle localization\nlengths. Near to the crosslink-density-controlled continuous\namorphous-solidification transition, this distribution obeys a scaling form: it\nhas a single peak at a lengthscale that diverges (along with the width of the\ndistribution) as the transition is approached. The modulus controlling\nmacroscale elastic shear deformations of the amorphous solid does not depend on\nthe distribution of localization lengths. However, it is natural to anticipate\nthat for deformations at progressively shorter lengthscales -- mesoscale\ndeformations -- the effective modulus exhibits a scale-dependence, softening as\nthe deformation lengthscale is reduced. This is because an increasing fraction\nof the localized particles are, in effect, liquid-like at the deformation\nlengthscale, and therefore less effective at contributing to the elastic\nresponse. In this paper, the relationship between the distribution of\nlocalization lengths and the scale-dependent elastic shear modulus is explored,\nand it is shown, within the setting of a replica mean-field theory, that the\neffective modulus does indeed exhibit scale-dependent softening. Through this\nsoftening, mesoscale elasticity provides a probe of the heterogeneity of the\nstate as characterized by the distribution of localization lengths. In\nparticular, the response to short-lengthscale elastic deformations is shown to\nshed light on the asymptotics of the universal localization-length distribution\nat short localization lengths.",
        "positive": "Molecular Interactions in Chiral Nematic Liquid Crystals and\n  Enantiotopic Discrimination through the NMR Spectra of Achiral Molecules I:\n  Rigid Solutes: We have developed a molecular theory for the enantiotopic discrimination in\nprochiral solutes dissolved in chiral nematic solvents by means of NMR\nspectroscopy. The leading rank tensor contributions to the proposed potential\nof mean torque include symmetric as well as antisymmetric terms with respect to\nspatial inversion, these lead to a consistent determination of all the\nprochiral solute symmetries for which enantiotopes are distinguishable by NMR\nand also to excellent quantitative agreement when tested against the available\nexperimental data for the rigid solute acenaphthene and for the moderately\nflexible ethanol."
    },
    {
        "anchor": "Active colloidal suspensions: Clustering and phase behavior: We review recent experimental, numerical, and analytical results on active\nsuspensions of self-propelled colloidal beads moving in (quasi) two dimensions.\nActive colloids form part of the larger theme of active matter, which is noted\nfor the emergence of collective dynamic phenomena away from thermal\nequilibrium. Both in experiments and computer simulations, a separation into\ndense aggregates, i.e., clusters, and a dilute gas phase has been reported even\nwhen attractive interactions and an alignment mechanism are absent. Here, we\ndescribe three experimental setups, discuss the different propelling\nmechanisms, and summarize the evidence for phase separation. We then compare\nexperimental observations with numerical studies based on a minimal model of\ncolloidal swimmers. Finally, we review a mean-field approach derived from first\nprinciples, which provides a theoretical framework for the density instability\ncausing the phase separation in active colloids.",
        "positive": "Cell Dynamic Simulations of Diblock Copolymer/Colloid Systems: The presence of nanoparticles in a diblock copolymer leads to changes in the\nmorphology and properties of the matrix and can produce highly organized hybrid\nmaterials. The resulting material properties depend not only on the polymer\ncomposition but also on the size, shape, and surface properties of the\ncolloids. The dynamics of this kind of systems using a hybrid mesoscopic\napproach has been studied in this work. A continuum description for the polymer\nis used, while colloids are individually resolved. The method allows for a\nvariable preference of the colloids, which can have different sizes, to the\ndifferent components the block copolymer is made of. The impact that the\nnanoparticle preference for either, both, or none of the blocks has on the\ncollective properties of nanoparticle-block copolymer composites can be\nanalyzed. Several experimental results are reproduced covering colloid-induced\nphase transition, particles' placement within the matrix, and the role of\nincompatibilities between colloids and monomers."
    },
    {
        "anchor": "Vertical drying of a suspension of sticks: Monte Carlo simulation for\n  continuous two-dimensional problem: The vertical drying of a two dimensional colloidal film containing\nzero-thickness sticks (lines) was studied by means of kinetic Monte Carlo (MC)\nsimulations. The continuous two-dimensional problem for both the positions and\norientations was considered. The initial state before drying was produced using\na model of random sequential adsorption with isotropic orientations of the\nsticks. During the evaporation, an upper interface falls with a linear velocity\nin the vertical direction and the sticks undergo translational and rotational\nBrownian motions. The MC simulations were run at different initial number\nconcentrations (the numbers of sticks per unit area), $p_i$, and solvent\nevaporation rates, $u$. For completely dried films, the spatial distributions\nof the sticks, the order parameters and the electrical conductivities of the\nfilms in both the horizontal, $x$, and vertical, $y$, directions were examined.\nSignificant evaporation-driven self-assembly and stratification of the sticks\nin the vertical direction was observed. The extent of stratification increased\nwith increasing values of $u$. The anisotropy of the electrical conductivity of\nthe film can be finely regulated by changes in the values of $p_i$ and $u$.",
        "positive": "Entropic Penalties in Circular DNA Assembly: The thermodynamic properties of DNA circular molecules are investigated by a\nnew path integral computational method which treats in the real space the\nfundamental forces stabilizing the molecule. The base pair and stacking\ncontributions to the classical action are evaluated separately by simulating a\nbroad ensemble of twisted conformations. We obtain, for two short sequences, a\nfree energy landscape with multiple wells corresponding to the most convenient\nvalues of helical repeat. Our results point to a intrinsic flexibility of the\ncircular structures in which the base pair fluctuations move the system from\none well to the next thus causing the local unwinding of the helix. The latter\nis more pronounced in the shorter sequence whose cyclization causes a higher\nbending stress. The entropic reductions associated to the formation of the\nordered helicoidal structure are estimated."
    },
    {
        "anchor": "Wetting of a Solid Surface by Active Matter: A lattice model is used to study repulsive active particles at a planar\nsurface. A rejection-free Kinetic Monte Carlo method is employed to\ncharacterize the wetting behaviour. The model predicts a mobility induced phase\nseparation of active particles, and the bulk coexistence of dense liquid-like\nand dilute vapour-like steady states is determined. An \"ensemble\", with a\nvarying number of particles, analogous to a grand canonical ensemble in\nequilibrium, is introduced. The formation and growth of the liquid film between\nthe solid surface and the vapour phase is investigated. For all of the\nactivities considered, the thickness of the adsorbed film exhibits a diverging\nbehaviour as the system is brought towards coexistence from the vapour side,\nsuggesting a complete wetting scenario along the full coexistence curve.",
        "positive": "Polyelectrolyte intelligent gels. Design and applications: In this chapter polyelectrolyte intelligent gels are examined along three\nbroad lines. The effects of different physical, chemical and biological stimuli\non gels response are analysed and mechanisms of response are outlined. The\nbroad range of biomedical applications of smart gels is reviewed and limits and\nperspectives of the proposed techniques and devices are crititically discussed.\nFinally, continuous modelling of gel electromechanochemistry is described,\nproviding quantitative tools to assess swelling equilibrium conditions and\ncoupled kinetics."
    },
    {
        "anchor": "Inverse design of multishape metamaterials: Multishape metamaterials exhibit more than one target shape change, e.g. the\nsame metamaterial can have either a positive or negative Poisson's ratio. So\nfar, multishape metamaterials have mostly been obtained by trial-and-error. The\ninverse design of multiple target deformations in such multishape metamaterials\nremains a largely open problem. Here, we demonstrate that it is possible to\ndesign metamaterials with multiple nonlinear deformations of arbitrary\ncomplexity. To this end, we introduce a novel sequential nonlinear method to\ndesign multiple target modes. We start by iteratively adding local constraints\nthat match a first specific target mode; we then continue from the obtained\ngeometry by iteratively adding local constraints that match a second target\nmode; and so on. We apply this sequential method to design up to 3 modes with\ncomplex shapes and we show that this method yields at least an 85% success\nrate. Yet we find that these metamaterials invariably host additional spurious\nmodes, whose number grows with the number of target modes and their complexity,\nas well as the system size. Our results highlight an inherent trade-off between\ndesign freedom and design constraints and pave the way towards multi-functional\nmaterials and devices.",
        "positive": "Enhanced diffusion and ordering of self-propelled rods: Starting from a minimal physical model of self propelled hard rods on a\nsubstrate in two dimensions, we derive a modified Smoluchowski equation for the\nsystem. Self -propulsion enhances longitudinal diffusion and modifies the mean\nfield excluded volume interaction. From the Smoluchowski equation we obtain\nhydrodynamic equations for rod concentration, polarization and nematic order\nparameter. New results at large scales are a lowering of the density of the\nisotropic-nematic transition and a strong enhancement of boundary effects in\nconfined self-propelled systems."
    },
    {
        "anchor": "Elastic moduli renormalization in self interacting stretchable\n  polyelectrolytes: We study the effect of intersegment interactions on the effective bending and\nstretching moduli of a semiflexible polymer chain with a finite stretching\nmodulus. For an interaction potential of a screened Debye-H\\\" uckel type\nrenormalization of the stretching modulus is derived on the same level of\napproximation as the celebrated Odijk-Skolnick-Fixman result for the bending\nmodulus. The presence of mesoscopic intersegment interaction potentials couples\nthe bending and stretching moduli in a manner different from that predicted by\nthe macroscopic elasticity theory. We advocate a fundamental change in the\nperspective regarding the dependence of elastic moduli of a flexible\npolyelectrolyte on the ionic conditions: stretchability. Not only are the\npersistence length as well as the stretching modulus dependent on the salt\nconditions in the solution, they are fundamentally coupled via the mesoscopic\nintersegment interaction potential. The theory presented here compares\nfavorably with recent experiments on DNA bending and stretching.",
        "positive": "Structural and Microscopic Relaxation Processes in Liquid Hydrogen\n  Fluoride: The high frequency collective dynamics of liquid hydrogen fluoride is studied\nby inelastic x-ray scattering on the coexistence curve at T = 239 K. The\ncomparison with existing molecular dynamics simulations shows the existence of\ntwo active relaxation processes with characteristic time scales in the\nsubpicosecond range. The observed scenario is very similar to that found in\nliquid water. This suggests that hydrogen bonded liquids behave similarly to\nother very different systems as simple and glass forming liquids, thus\nindicating that these two relaxation processes are universal features of the\nliquid state."
    },
    {
        "anchor": "Short- and Long-Term Statistical Properties of Heartbeat Time-Series in\n  Healthy and Pathological Subjects: We analize heartbeat time-series corresponding to several groups of\nindividuals (healthy, heart transplanted, with congestive heart failure (CHF),\nafter myocardial infarction (MI), hypertensive), looking for short- and\nlong-time statistical behaviors. In particular we study the persistency\npatterns of interbeat times and interbeat-time variations. Long-range\ncorrelations are revealed using an information-based technique which makes a\nwise use of the available statistics. The presence of strong long-range time\ncorrelations seems to be a general feature for all subjects, with the exception\nof some CHF individuals. We also show that short time-properties detected in\nhealthy subjects, and seen also in hypertensive and MI patients, and completely\nabsent in the trasplanted, are characterized by a general behavior when we\napply a proper coarse-graining procedure for time series analysis.",
        "positive": "Dense ionic fluids confined in planar capacitors: in- and out-of-plane\n  structure from classical density functional theory: The ongoing scientific interest in the properties and structure of electric\ndouble layers (EDLs) stems from their pivotal role in (super)capacitive energy\nstorage, energy harvesting, and water treatment technologies. Classical density\nfunctional theory (DFT) is a promising framework for the study of the in- and\nout-of-plane structural properties of double layers. Supported by molecular\ndynamics simulations, we demonstrate the adequate performance of DFT for\nanalyzing charge layering in the EDL perpendicular to the electrodes. We\ndiscuss charge storage and capacitance of the EDL and the impact of screening\ndue to dielectric solvents. We further calculate, for the first time, the\nin-plane structure of the EDL within the framework of DFT. While our\nout-of-plane results already hint at structural in-plane transitions inside the\nEDL, which have been observed recently in simulations and experiments, our DFT\napproach performs poorly in predicting in-plane structure in comparison to\nsimulations. However, our findings isolate fundamental issues in the\ntheoretical description of the EDL within the primitive model and point towards\nlimitations in the performance of DFT in describing the out-of-plane structure\nof the EDL at high concentrations and potentials."
    },
    {
        "anchor": "Self-consistent Treatment of Copolymers with Arbitrary Sequences: Using the Gaussian Ansatz for the monomer-monomer correlation functions we\nderive a set of the self-consistent equations for determination of the\nconformational state in the bead-and-spring copolymer model. The latter is\nbased on the Edwards type effective free energy functional with arbitrary\ntwo-body interaction matrix. The rate of conformational changes in kinetics may\nbe expressed via the instantaneous gradients of the variational free energy\nfunctional in the space of the averaged dynamical variables. We study the\nequilibrium and kinetics for some periodic and random aperiodic amphiphilic\nsequences in infinitely diluted solution. Typical equilibrium phase diagrams\nare elucidated and the conformational structure of different states is\ndiscussed. The kinetics of compaction of an amphiphilic copolymer to the\nglobular state proceeds through formation of locally frustrated non-equilibrium\nstructures. This leads to a rather complicated multistep kinetic process. We\nobserve that even a small modification in the primary sequence of a copolymer\nmay significantly change its kinetic folding properties.",
        "positive": "Bending and Base-Stacking Interactions in Double-Stranded Semiflexible\n  Polymer: Simple expressions for the bending and the base-stacking energy of\ndouble-stranded semiflexible biopolymers (such as DNA and actin) are derived.\nThe distribution of the folding angle between the two strands is obtained by\nsolving a Schr\\\"{o}dinger equation variationally. Theoretical results based on\nthis model on the extension versus force and extension versus degree of\nsupercoiling relations of DNA chain are in good agreement with the experimental\nobservations of Cluzel {\\it et al.} [Science {\\bf 271}, 792 (1996)], Smith {\\it\net al.} [{\\it ibid.} {\\bf 271}, 795 (1996)], and Strick {\\it et al.} [{\\it\nibid.} {\\bf 271}, 1835 (1996)]."
    },
    {
        "anchor": "Defects induced polymer aggregates: A theoretical study: . We consider three dimensional model of the Gaussian polymer chain in the\npresence of defects to understand the formation of a polymer aggregate where\nthe aggregate is induced by the defects. The defects are acting as an\nattractive centres of the monomers and it induces aggregation of the monomers\nof the chain around the defects. It has been shown using the analytical\ncalculations that the formation of a polymer aggregates are favoured when the\ndefects have extensions in all the possible three dimensions. We have also\ncalculated relevant other thermo-dynamical parameters (i. e. the average number\nof the monomers and the average size of the chain about the defect line) of the\npolymer aggregates to justify our findings.",
        "positive": "Transport coefficients of off-lattice mesoscale-hydrodynamics simulation\n  techniques: The viscosity and self-diffusion constant of particle-based mesoscale\nhydrodynamic methods, multi-particle collision dynamics (MPC) and dissipative\nparticle dynamics (DPD), are investigated, both with and without\nangular-momentum conservation. Analytical results are derived for fluids with\nan ideal-gas equation of state and a finite-time-step dynamics, and compared\nwith simulation data. In particular, the viscosity is derived in a general form\nfor all variants of the MPC method. In general, very good agreement between\ntheory and simulations is obtained."
    },
    {
        "anchor": "A simple model of the charge transfer in DNA-like substances: We present a very simple model for the study of charge transport in a\nmolecule patterned on B-DNA. In this model we use a discrete non-linear\nSchr\\\"{o}dinger equation to describe electrons propagating along the\nsugar-phosphate backbone of the DNA molecule. We find that in this model, for a\ngiven nonlinearity, the transport is controlled by $J$, a parameter which\nrelates to the electronic coupling between different molecules on the backbone.\nFor smaller values of $J$ we have localised states while at higher values of\n$J$ the soliton field is spread out and through its interaction with the\nlattice it has stronger effects on the distortion of the lattice.",
        "positive": "Universal criterion for designability of heteropolymers: Proteins are an example of heteropolymers able to self-assemble in specific\ntarget structures. The self-assembly of designed artificial heteropolymers is\nstill, to the best of our knowledge, not possible with control over the single\nchain self-assembling properties comparable to what natural proteins can\nachieve. What artificial heteropolymers lacks compared to bio-heteropolymers\nthat grants the latter such a versatility? Is the geometry of the protein\nskeleton the only a particular choice to be designable? Here we introduce a\ngeneral criteria to discriminate which polymer backbones can be designed to\nadopt a predetermined structure. With our approach we can explore different\npolymer backbones and different amino acids alphabets. By comparing the radial\ndistribution functions of designable and not-designable scenarios we identify\nas designability criteria the presence of a particular peak in the radial\ndistribution function that dominates over the random packing of the\nheteropolymer. We show that the peak is a universal feature of all designable\nheteropolymers, as it is dominating also the radial distribution function of\nnatural proteins. Our finding can help in understanding the key features that\nmake proteins a highly designable system. The criteria that we present can be\napplied to engineer new types of self-assembling modular polymers that will\nopen new applications for polymer based material science."
    },
    {
        "anchor": "Interface dynamics in shear-banding flow of giant micelles: We report on a non trivial dynamics of the interface between shear bands\nfollowing a start-up of flow in a semi-dilute wormlike micellar system\ninvestigated using a combination of mechanical and optical measurements. During\nthe building of the banding structure, we observed the stages of formation,\nmigration of the interface between bands and finally the destabilization of\nthis interface along the vorticity axis. The mechanical signature of these\nprocesses has been indentified in the time series of the shear stress. The\ninterface instability occurs all along the stress plateau, the asymptotic\nwavelength of the patterns increasing with the control parameter typically from\na fraction of the gap width to about four times the gap width. Three main\nregimes of dynamics are highlighted : a spatially stable oscillating mode\napproximately at the middle of the coexistence region flanked by two ranges\nwhere the dynamics appears more exotic with propagative and chaotic events\nrespectively at low and high shear rates. The distribution of small particles\nseeded in the solution strongly suggests that the flow is three-dimensional.\nFinally, we demonstrate that the shear-banding scenario described in this paper\nis not specific to our system.",
        "positive": "Role of solvent for globular proteins in solution: The properties of the solvent affect the behavior of the solution. We propose\na model that accounts for the contribution of the solvent free energy to the\nfree energy of globular proteins in solution. For the case of an attractive\nsquare well potential, we obtain an exact mapping of the phase diagram of this\nmodel without solvent to the model that includes the solute-solvent\ncontribution. In particular we find for appropriate choices of parameters upper\ncritical points, lower critical points and even closed loops with both upper\nand lower critical points, similar to one found before [Macromolecules, 36,\n5845 (2003)]. In the general case of systems whose interactions are not\nattractive square wells, this mapping procedure can be a first approximation to\nunderstand the phase diagram in the presence of solvent. We also present\nsimulation results for both the square well model and a modified Lennard-Jones\nmodel."
    },
    {
        "anchor": "Surmounting Barriers: The Benefit of Hydrodynamic Interactions: We experimentally and theoretically investigate the collective behavior of\nthree colloidal particles that are driven by a constant force along a toroidal\ntrap. Due to hydrodynamic interactions, a characteristic limit cycle is\nobserved. When we additionally apply a periodic sawtooth potential, we find a\nnovel caterpillar-like motional sequence that is dominated by hydrodynamic\ninteractions and promotes the surmounting of potential barriers by the\nparticles.",
        "positive": "Lipid membrane deformation in response to a local pH modification:\n  theory and experiments: We study the deformation of a lipid membrane in response to a local pH\nmodification. Experimentally, a basic solution is microinjected close to a\ngiant unilamellar vesicle. A local deformation appears in the zone of the\nmembrane that is closest to the micropipette, and relaxes when the injection is\nstopped. A theoretical description of this phenomenon is provided. It takes\nfully into account the spatiotemporal evolution of the concentration of\nhydroxide ions during and after the microinjection, as well as the linear\ndynamics of the membrane. This description applies to a local injection of any\nsubstance that reacts reversibly with the membrane lipids. We compare\nexperimental data obtained in the domain of small deformations to the results\nof our linear description, and we obtain a good agreement between theory and\nexperiments. In addition, we present direct experimental observations of the pH\nprofile on the membrane during and after the microinjection, using pH-sensitive\nfluorescent lipids."
    },
    {
        "anchor": "Sliding and translational diffusion of molecular phases confined into\n  nanotubes: The remaining dynamical degrees of freedom of molecular fluids confined into\ncapillaries of nano to sub-nanometer diameter are of fundamental relevance for\nfuture developments in the field of nanofluidics. These properties cannot be\nsimply deduced from the bulk one since the derivation of macroscopic\nhydrodynamics most usually breaks down in nanoporous channels and additional\neffects have to be considered. In the present contribution, we review some\ngeneral phenomena, which are expected to occur when manipulating fluids under\nconfinement and ultraconfinement conditions.",
        "positive": "A computational model of self-organized shape dynamics of active\n  surfaces in fluids: Mechanochemical processes on surfaces such as the cellular cortex or\nepithelial sheets, play a key role in determining patterns and shape changes of\nbiological systems. To understand the complex interplay of hydrodynamics and\nmaterial flows on such active surfaces requires novel numerical tools. Here, we\npresent a finite-element method for an active deformable surface interacting\nwith the surrounding fluids. The underlying model couples surface and bulk\nhydrodynamics to surface flow of a diffusible species which generates active\ncontractile forces. The method is validated with previous results based on\nlinear stability analysis and shows almost perfect agreement regarding\npredicted patterning. Away from the linear regime we find rich non-linear\nbehavior, such as the presence of multiple stationary states. We study the\nformation of a contractile ring on the surface and the corresponding shape\nchanges. Finally, we explore mechanochemical pattern formation on various\nsurface geometries and find that patterning strongly adapts to local surface\ncurvature. The developed method provides a basis to analyze a variety of\nsystems that involve mechanochemical pattern formation on active surfaces\ninteracting with surrounding fluids."
    },
    {
        "anchor": "Hydrodynamics defines the stable swimming direction of spherical\n  squirmers in a nematic liquid crystal: We present a study of the hydrodynamics of an active particle, a model\nsquirmer, in an envi- ronment with a broken rotational symmetry: a nematic\nliquid crystal. By combining simulations with analytic calculations, we show\nthat the hydrodynamic coupling between the squirmer flow field and liquid\ncrystalline director can lead to re-orientation of the swimmers. The preferred\norientation depends on the exact details of the squirmer flow field. In a\nsteady state, pushers are shown to swim parallel with the nematic director\nwhile pullers swim perpendicular to the nematic director. This behaviour arises\nsolely from hydrodynamic coupling between the squirmer flow field and\nanisotropic viscosities of the host fluid. Our results suggest that an\nanisotropic swimming medium can be used to characterise and guide spherical\nmicroswimmers in the bulk.",
        "positive": "Testing theories of the glass transition with the same liquid, but many\n  kinetic rules: We study the glass transition by exploring a broad class of kinetic rules\nthat can significantly modify the normal dynamics of super-cooled liquids,\nwhile maintaining thermal equilibrium. Beyond the usual dynamics of liquids,\nthis class includes dynamics in which a fraction $(1-f_R)$ of the particles can\nperform pairwise exchange or 'swap moves', while a fraction $f_P$ of the\nparticles can only move along restricted directions. We find that (i) the\nlocation of the glass transition varies greatly but smoothly as $f_P$ and $f_R$\nchange and (ii) it is governed by a linear combination of $f_P$ and $f_R$.\n(iii) Dynamical heterogeneities are not governed by the static structure of the\nmaterial. Instead, they are similar at the glass transition across the ($f_R$,\n$f_P$) diagram. These observations are negative items for some existing\ntheories of the glass transition, particularly those reliant on growing\nthermodynamic order or locally favored structure, and open new avenues to test\nother approaches."
    },
    {
        "anchor": "Melting of persistent double-stranded polymers: Motivated by recent DNA-pulling experiments, we revisit the Poland-Scheraga\nmodel of melting a double-stranded polymer. We include distinct bending\nrigidities for both the double-stranded segments, and the single-stranded\nsegments forming a bubble. There is also bending stiffness at the branch points\nbetween the two segment types. The transfer matrix technique for single\npersistent chains is generalized to describe the branching bubbles. Properties\nof spherical harmonics are then exploited in truncating and numerically solving\nthe resulting transfer matrix. This allows efficient computation of phase\ndiagrams and force-extension curves (isotherms). While the main focus is on\nexposition of the transfer matrix technique, we provide general arguments for a\nreentrant melting transition in stiff double strands. Our theoretical approach\ncan also be extended to study polymers with bubbles of any number of strands,\nwith potential applications to molecules such as collagen.",
        "positive": "The Early Crystal Nucleation Process in Hard Spheres shows Synchronised\n  Ordering and Densification: We investigate the early part of the crystal nucleation process in the hard\nsphere fluid using data produced by computer simulation. We find that hexagonal\norder manifests continuously in the overcompressed liquid, beginning\napproximately one diffusion time before the appearance of the first\n`solid-like' particle of the nucleating cluster, and that a collective influx\nof particles towards the nucleation site occurs simultaneously to the ordering\nprocess: the density increases leading to nucleation are generated by the same\nindividual particle displacements as the increases in order. We rule out the\npresence of qualitative differences in the early nucleation process between\nmedium and low overcompressions, and also provide evidence against any\nseparation of translational and orientational order on the relevant\nlengthscales."
    },
    {
        "anchor": "A random walk description of the heterogeneous glassy dynamics of\n  attracting colloids: We study the heterogeneous dynamics of attractive colloidal particles close\nto the gel transition using confocal microscopy experiments combined with a\ntheoretical statistical analysis. We focus on single particle dynamics and show\nthat the self part of the van Hove distribution function is not the Gaussian\nexpected for a Fickian process, but that it reflects instead the existence, at\nany given time, of colloids with widely different mobilities. Our confocal\nmicroscopy measurements can be described well by a simple analytical model\nbased on a conventional continuous time random walk picture, as already found\nin several other glassy materials. In particular, the theory successfully\naccounts for the presence of broad tails in the van Hove distributions that\nexhibit exponential, rather than Gaussian, decay at large distance.",
        "positive": "Critical phenomena of RNA-like polymers -- a synopsis: This work examines field theories for RNA-like polymers with single strand\nand double strand polymers and a periodic base sequence. These field theories\noriginate from lattice models, describe polymers in a good solvent, and in\nprinciple exactly describe the critical behavior. A central role is played by\nthe conventional one-component branched polymer and the mapping of the\ncorresponding field theory to the Lee-Yang field theory in two less dimensions.\nCritical phenomena in the context of polymers as well as the Lee-Yang model\nentail pecularities, which we derive in detail. A new result is that the\ncritical point of RNA-like branched polymers (with periodic base sequence)\nlooks like the critical point of the classical one-component branched polymer,\nbut with one more critical exponent for the single strand polymer. A random\nbase sequence generates additional relevant interactions, and invalidates the\nsimple picture."
    },
    {
        "anchor": "How soft repulsion enhances the depletion mechanism: We investigate binary mixtures of large colloids interacting through soft\npotentials with small, ideal depletants. We show that softness has a dramatic\neffect on the resulting colloid-colloid effective potential when the\ndepletant-to-colloid size ratio $q$ is small, with significant consequences on\nthe colloidal phase behaviour. We also provide an exact relation that allows us\nto obtain the effective pair potential for {\\it any} type of colloid-depletant\ninteractions in the case of ideal depletants, without having to rely on\ncomplicated and expensive full-mixture simulations. We also show that soft\nrepulsion among depletants further enhances the tendency of colloids to\naggregate. Our theoretical and numerical results demonstrate that --- in the\nlimit of small $q$ --- soft mixtures cannot be mapped onto hard systems and\nhence soft depletion is not a mere extension of the widely used Asakura-Oosawa\npotential.",
        "positive": "Analytical expression for end-to-end- auto correlation function of a\n  long chain polymer molecule in solution: A diffusion-like theory for real time end-to-end distance of a long polymer\nchain in dilute solution is formulated. We give a detailed analytical\nexpression for the end-to-end distance auto-correlation function of a long\nchain polymer in solution. The physical problem of dynamics of end-to-end\ndistance can be modeled mathematically with the use of a Smoluchowski-like\nequation. Using this equation analytical expression for end-to-end distance\nauto-correlation function is derived. We find that this auto-correlation\nfunction varies with several parameters such as length of the polymer (N), bond\nlength (b) and the relaxation time ${\\tau_R}$."
    },
    {
        "anchor": "Efficiency of surface-driven motion: nano-swimmers beat micro-swimmers: Surface interactions provide a class of mechanisms which can be employed for\npropulsion of micro- and nanometer sized particles. We investigate the related\nefficiency of externally and self-propelled swimmers. A general scaling\nrelation is derived showing that only swimmers whose size is comparable to, or\nsmaller than, the interaction range can have appreciable efficiency. An upper\nbound for efficiency at maximum power is 1/2. Numerical calculations for the\ncase of diffusiophoresis are found to be in good agreement with analytical\nexpressions for the efficiency.",
        "positive": "Sheared phase-separating binary mixtures with surface diffusion: The phase-separation process of a binary mixture with\norder-parameter-dependent mobility under shear flow is numerically studied. The\nordering is characterized by an alternate stretching and bursting of domains\nwhich produce oscillations in the physical observables. The amplitude of such\nmodulations reduce in time when the mobility vanishes in the bulk phase,\ndisfavoring the growth of bubbles coming from bursted domains. We propose two\nequations for the typical sizes $R_x$ and $R_y$ of domains finding the\nlong-time behaviors $R_x \\sim t^{5/4}$ and $R_y \\sim t^{1/4}$ in the flow and\nshear directions, respectively, in the case of surface diffusion. A reduction\nof the excess viscosity with increasing shear rate is observed in simulations."
    },
    {
        "anchor": "Geometrical Properties of Two-Dimensional Interacting Self-Avoiding\n  Walks at the Theta-Point: We perform a Monte Carlo simulation of two-dimensional N-step interacting\nself-avoiding walks at the theta point, with lengths up to N=3200. We compute\nthe critical exponents, verifying the Coulomb-gas predictions, the theta-point\ntemperature T_theta = 1.4986(11), and several invariant size ratios. Then, we\nfocus on the geometrical features of the walks, computing the instantaneous\nshape ratios, the average asphericity, and the end-to-end distribution\nfunction. For the latter quantity, we verify in detail the theoretical\npredictions for its small- and large-distance behavior.",
        "positive": "Micromachined piezoelectric membranes with high nominal quality factors\n  in newtonian liquid media: A Lamb's model validation at the microscale: Although extensively presented as one of the most promising silicon-based\nmicromachined sensor adapted to real-time measurements in liquid media, the\ncantilevered structure still suffers from its quality factor (Q) dramatic\ndependence on the liquid viscosity thus lowering the measurement resolution. In\nthis paper, micromachined piezoelectric membranes are introduced as a potential\nalternative to the cantilevers for biological applications. HighQ-factors (up\nto 150) of micromachined piezoelectric membranes resonating in various liquid\nmixtures (water/glycerol and water/ethanol) are thus reported and a theoretical\nmodel proposed by Lamb [H. Lamb, On the vibrations of an elastic plate in\ncontact with water, Proc. Roy. Soc. Lond. A 98 (1920) 205?216] is validated for\nmicroscale structures proving that the variation of the liquid viscosity (if\nlower than 10 cP) has no effect on the dynamic behavior of the membranes. To\nconclude, two types of experiments were performed in water/glycerol mixtures:\nin-flow (with liquid continuously flowing on the devices) and in-spot (with\nindividual membranes oscillating in a 5 $\\mu$L volume of liquid). The results\ninterestingly showed that for the in-spot configuration the Q-factor values are\nmore than two-fold the ones corresponding to in-flow measurements thus\nproviding alternative insights into the way to conceive ideal configurations\nfor real-time biological measurements in liquid media."
    },
    {
        "anchor": "Normal versus anomalous self-diffusion in two-dimensional fluids: Memory\n  function approach and generalized asymptotic Einstein relation: Based on the generalized Langevin equation for the momentum of a Brownian\nparticle a generalized asymptotic Einstein relation is derived. It agrees with\nthe well-known Einstein relation in the case of normal diffusion but continues\nto hold for sub- and super-diffusive spreading of the Brownian particle's mean\nsquare displacement. The generalized asymptotic Einstein relation is used to\nanalyze data obtained from molecular dynamics simulations of a two-dimensional\nsoft disk fluid. We mainly concentrated on medium densities for which we found\nsuper-diffusive behavior of a tagged fluid particle. At higher densities a\nrange of normal diffusion can be identified. The motion presumably changes to\nsub-diffusion for even higher densities.",
        "positive": "Aqueous Nanoclusters Govern Ion Partitioning in Dense Polymer Membranes: The uptake and sorption of charged molecules by responsive polymer membranes\nand hydrogels in aqueous solutions is of key importance for the development of\nsoft functional materials. Here we investigate the partitioning of simple\nmonoatomic (Na$^+$, K$^+$, Cs$^+$, Cl$^-$, I$^-$) and one molecular ion\n(4-nitrophenolate; NP$^-$) within a dense, electroneutral\npoly($N$-isopropylacrylamide) membrane using explicit-water molecular dynamics\nsimulations. Inside the predominantly hydrophobic environment water distributes\nin a network of polydisperse water nanoclusters. The average cluster size\ndetermines the mean electrostatic self-energy of the simple ions, which\npreferably reside deeply inside them; we therefore find substantially larger\npartition ratios $K\\simeq\\>$10$^{-1}$ than expected from a simple Born picture\nusing a uniform dielectric constant. Despite their irregular shapes we observe\nthat the water clusters possess a universal negative electrostatic potential\nwith respect to their surrounding, as is known for aqueous liquid-vapor\ninterfaces. This potential, which we find concealed in cases of symmetric\nmonoatomic salts, can dramatically impact the transfer free energies of larger\ncharged molecules because of their weak hydration and increased affinity to\ninterfaces. Consequently, and in stark contrast to the simple ions, the\nmolecular ion NP$^-$ can have a partition ratio much larger than unity,\n$K\\simeq\\>$10-30 (depending on the cation type) or even $10^3$ in excess of\nmonovalent salt, which explains recent observations of enhanced reaction\nkinetics of NP$^-$ reduction catalyzed within dense polymer networks. These\nresults also suggest that ionizing a molecule can even enhance the partitioning\nin a collapsed, rather hydrophobic gel, which strongly challenges the\ntraditional simplistic reasoning."
    },
    {
        "anchor": "Finite Phase-separation FRET II: Determination of domain size from\n  simulated data: We have developed a new model to describe FRET efficiency (E FRET) between\nfreely-diffusing membrane probes in phase-separated bilayers (Finite\nPhase-separation FRET, or FP-FRET), that in principle applies to any system\nwhere phase domain dimensions are larger than ~Ro . Here we use Monte Carlo\ntechniques to simulate E FRET for a range of probe partitioning behaviors and\ndomain sizes, and then fit the simulated data to the FP-FRET model to recover\nsimulation parameters. We find that FP-FRET can determine domain size to within\n5% of simulated values for domain diameters up to ~ 5Ro, and to within 15% for\ndiameters up to ~ 20Ro . We also investigated the performance of the model in\ncases where specific model assumptions are not valid.",
        "positive": "Nonlinear Electrophoresis of Highly Charged Nonpolarizable Particles: Nonlinear field dependence of electrophoresis in high fields has been\ninvestigated theoretically, yet experimental studies have failed to reach\nconsensus on the effect. In this work, we present a systematic study on the\nnonlinear electrophoresis of highly charged submicron particles in applied\nelectric fields of up to several kV/cm. First, the particles are characterized\nin the low-field regime at different salt concentrations and the surface charge\ndensity is estimated. Subsequently, we use microfluidic channels and video\ntracking to systematically characterize the nonlinear response over a range of\nfield strengths. Using velocity measurements on the single particle level, we\nprove that nonlinear effects are present at electric fields and surface charge\ndensities that are accessible in practical conditions. Finally, we show that\nnonlinear behavior leads to unexpected particle trapping in channels."
    },
    {
        "anchor": "Defects in nematic membranes can buckle into pseudospheres: A nematic membrane is a sheet with embedded orientational order, which can\noccur in biological cells, liquid crystal films, manufactured materials, and\nother soft matter systems. By formulating the free energy of nematic films\nusing tensor contractions from differential geometry, we elucidate the elastic\nterms allowed by symmetry, and indicate differences from hexatic membranes. We\nfind that topological defects in the orientation field can cause the membrane\nto buckle over a size set by the competition between surface tension and\nin-plane elasticity. In the absence of bending rigidity the resulting shape is\nuniversal, known as a parabolic pseudosphere or a revolved tractrix. Bending\ncosts oppose such buckling and modify the shape in a predictable manner. In\nparticular, the anisotropic rigidities of nematic membranes lead to different\nshapes for aster and vortex defects, in principle enabling measurement of\ncouplings specific to nematic membranes.",
        "positive": "Runaway Transition in Irreversible Polymer Condensation with Cyclisation: The process of polymer condensation, i.e. the formation of bonds between\nreactive end-groups, is ubiquitous in both industry and biology. Here we study\ngeneric systems undergoing polymer condensation in competition with\ncyclisation. Using a generalised Smoluchowski theory, molecular dynamics\nsimulations and experiments using DNA and T4 ligase, we find that this system\ndisplays a transition, from a regime with finite-length chains at infinite time\nand dominated by rings to one dominated by linear polymers that grow in time.\nFinally, we show that fluids prepared close to the transition may have\nprofoundly different compositions and rheology at large condensation times."
    },
    {
        "anchor": "Pulse propagation in discrete systems of coupled excitable cells: Propagation of pulses in myelinated fibers may be described by appropriate\nsolutions of spatially discrete FitzHugh-Nagumo systems. In these systems,\npropagation failure may occur if either the coupling between nodes is not\nstrong enough or the recovery is too fast. We give an asymptotic construction\nof pulses for spatially discrete FitzHugh-Nagumo systems which agrees well with\nnumerical simulations and discuss evolution of initial data into pulses and\npulse generation at a boundary. Formulas for the speed and length of pulses are\nalso obtained.",
        "positive": "First-Principles Experimental Demonstration of Ferroelectricity in a\n  Thermotropic Nematic Liquid Crystal: Spontaneous Polar Domains and Striking\n  Electro-Optics: We report the experimental determination of the structure and response to\napplied electric field of the lower-temperature nematic phase of the previously\nreported calamitic compound\n4-[(4-nitrophenoxy)carbonyl]phenyl2,4-dimethoxybenzoate (RM734). We exploit its\nelectro-optics to visualize the appearance, in the absence of applied field, of\na permanent electric polarization density, manifested as a spontaneously broken\nsymmetry in distinct domains of opposite polar orientation. Polarization\nreversal is mediated by field-induced domain wall movement, making this phase\nferroelectric, a 3D uniaxial nematic having a spontaneous, reorientable,\npolarization locally parallel to the director. This polarization density\nsaturates at a low temperature value of ~ 6 microcoulombs/cm-sqd, the largest\never measured for an organic material or for any fluid. This polarization is\ncomparable to that of solid state ferroelectrics, and is close to the average\nvalue obtained by assuming perfect, polar alignment of molecular long axes in\nthe nematic. We find a host of spectacular optical and hydrodynamic effects\ndriven by ultra-low applied field (E~1V/cm), produced by the coupling of the\nlarge polarization to nematic birefringence and flow. Electrostatic\nself-interaction of the polarization charge renders the transition from the\nnematic phase mean-field-like and weakly first-order, and controls the director\nfield structure of the ferroelectric phase. Atomistic molecular dynamics\nsimulation reveals short-range polar molecular interactions that favor\nferroelectric ordering, including a tendency for head-to-tail association into\npolar, chain-like assemblies having polar lateral correlations. These results\nindicate a significant potential for transformative new nematic science and\ntechnology based on the enhanced understanding, development, and exploitation\nof molecular electrostatic interaction."
    },
    {
        "anchor": "The emergence of supramolecular forces from lattice kinetic models of\n  non ideal fluids: applications to the rheology of soft glassy meterials: A systematic study for a single-specie lattice Boltzmann model with\nfrustrated-short range attractive and mid/long-range repulsive-interactions is\npresented. The equilibrium analysis is performed along the guidelines proposed\nby [X. Shan, Phys. Rev. E 77, 066702 (2008)] and allows us to determine the\nsurface tension density and the resulting disjoining pressure developing in a\nthin film when two interfaces overlap. Numerical simulations of confined flows\nare then performed with a multicomponent model and are successfully tested\nagainst the recent suggestion by Bocquet and coworkers on the existence of a\ncooperative length underlying the non-local rheology of highly confined\nsoft-glassy materials [Goyon et al., Nature 454, 84-87 (2008); Soft Matter 6,\n2668-2678 (2010)].",
        "positive": "Knots are Generic Stable Phases in Semiflexible Polymers: Semiflexible polymer models are widely used as a paradigm to understand\nstructural phases in biomolecules including folding of proteins. Since stable\nknots are not so common in real proteins, the existence of stable knots in\nsemiflexible polymers has not been explored much. Here, via extensive replica\nexchange Monte Carlo simulation we investigate the same for a bead-stick and a\nbead-spring homopolymer model that covers the whole range from flexible to\nstiff. We establish the fact that the presence of stable knotted phases in the\nphase diagram is dependent on the ratio $r_b/r_{\\rm{min}}$ where $r_b$ is the\nequilibrium bond length and $r_{\\rm{min}}$ is the distance for the strongest\nnonbonded contacts. Our results provide evidence for both models that if the\nratio $r_b/r_{\\rm{min}}$ is outside a small window around unity then depending\non the bending stiffness one always encounters stable knotted phases along with\nthe usual frozen and bent-like structures at low temperatures. These findings\nprompt us to conclude that knots are generic stable phases in semiflexible\npolymers."
    },
    {
        "anchor": "Is the friction angle the maximum slope of a free surface of a non\n  cohesive material?: Starting from a symmetric triangular pile with a horizontal basis and\nrotating the basis in the vertical plane, we have determined the evolution of\nthe stress distribution as a function of the basis inclination using Finite\nElements method with an elastic-perfectly plastic constitutive model, defined\nby its friction angle, without cohesion. It is found that when the yield\nfunction is the Drucker-Prager one, stress distribution satisfying equilibrium\ncan be found even when one of the free-surface slopes is larger than the\nfriction angle. This means that piles with a slope larger than the friction\nangle can be (at least) marginally stable and that slope rotation is not always\na destabilising perturbation direction. On the contrary, it is found that the\nslope cannot overpass the friction angle when a Mohr-Coulomb yield function is\nused. Theoretical explanation of these facts is given which enlightens the role\nplaid by the intermediate principal stress in both cases of the Mohr-Coulomb\ncriterion and of the Drucker-Prager one. It is then argued that the\nMohr-Coulomb criterion assumes a spontaneous symmetry breaking, as soon as the\ntwo smallest principal stresses are different ; this is not physical most\nlikely; so this criterion shall be replaced by a Drucker-Prager criterion in\nthe vicinity of the equality, which leads to the previous anomalous behaviour ;\nso these numerical computations enlighten the avalanche process: they show that\nno dynamical angle larger than the static one is needed to understand\navalanching. It is in agreement with previous experimental results.\nFurthermore, these results show that the maximum angle of repose can be\nmodified using cyclic rotations; we propose a procedure that allows to achieve\na maximum angle of repose to be equal to the friction angle .",
        "positive": "Deflection and oscillations of an anchored elastic fiber embedded in a\n  quasistatic two-dimensional foam flow: We study the deflection and fluctuations of a clamped elastic fiber embedded\nin 2D foam under quasistatic flow. At all times, the fiber conformation results\nfrom the elasto-capillary interactions with the foam. We independently measure\nthe action of capillary and pressure forces on the fiber, and show that the\nfiber deformation is adequately described assuming a uniform continuous normal\nforce acting on it. When bending energy exceeds a threshold value, the fiber\nrelaxes to a less deflected shape, generating a cascade of plastic\nrearrangements within the foam, and the process repeats periodically. We\nanalyze the statistical distributions of stored and released energy, and\nestimate the yield stress and shear modulus of the foam, as well as the number\nof elementary plastic events involved in a cascade."
    },
    {
        "anchor": "Bubbles and liquid films resisting drainage, evaporation and\n  nuclei-induced bursting: Soap bubbles are by essence fragile and ephemeral. Depending on their\ncomposition and environment, bubble bursting can be triggered by\ngravity-induced drainage and/or the evaporation of the liquid and/or the\npresence of nuclei. They can also shrink due to the diffusion of the inner gas\nin the outside atmosphere induced by Laplace overpressure. In this paper, we\ndesign bubbles made of a composite liquid film able to neutralize all these\neffects and keep their integrity for more than one year in a standard\natmosphere. The unique properties of this composite film are rationalized with\na nonlinear model and used to design complex objects.",
        "positive": "Dipole-dipole correlations in the nematic phases of symmetric\n  cyanobiphenyl dimers and their binary mixtures with 5CB: We report on the temperature dependence of birefringence and of the static\ndielectric permittivity tensor in a series of binary mixtures between the\nsymmetric, bent-shaped, 1\",9\"-bis(4-cyanobiphenyl-4'-yl) nonane (CB9CB) dimer\nand the monomeric nematogen 5CB. In the studied composition range the mixtures\nexhibit two nematic phases with distinct birefringence and dielectric features.\nBirefringence measurements are used to estimate the temperature dependence of\nthe tilt between the axis defining the nanoscale helical modulation of the low\ntemperature nematic phase with the (local) direction of the maximal alignment\nof the cyanobiphenyl units. Planar as well as magnetically and/or electrically\naligned samples are used to measure the perpendicular and parallel components\nof the dielectric permittivity in both nematic phases. A self-consistent\nmolecular field theory that takes into account flexibility and symmetry of the\nconstituent mesogens is introduced for the calculation of order parameters and\nintra-molecular orientational dipolar correlations of the flexible dimers as a\nfunction of temperature/concentration. Utilising the tilt angle, as calculated\nfrom the birefringence measurements, and the predictions of the molecular\ntheory, dielectric permittivity is modelled in the framework of the anisotropic\nversion of the Kirkwood-Frohlich theory. Using the inter-molecular Kirkwood\ncorrelation factors as adjustable parameters, excellent agreement between\ntheory and permittivity measurements across the whole temperature range and\ncomposition of the mixtures is obtained. The importance of the orientational,\nintra- and inter-molecular, dipolar correlations, their relative impact on the\nstatic dielectric properties, as well as their connection with the local\nstructure of the nematic phases of bent-shaped bimesogens, is discussed."
    },
    {
        "anchor": "New universality class for the fragmentation of plastic materials: We present an experimental and theoretical study of the fragmentation of\npolymeric materials by impacting polypropylene particles of spherical shape\nagainst a hard wall. Experiments reveal a power law mass distribution of\nfragments with an exponent close to 1.2, which is significantly different from\nthe known exponents of three-dimensional bulk materials. A 3D discrete element\nmodel is introduced which reproduces both the large permanent deformation of\nthe polymer during impact, and the novel value of the mass distribution\nexponent. We demonstrate that the dominance of shear in the crack formation and\nthe plastic response of the material are the key features which give rise to\nthe emergence of the novel universality class of fragmentation phenomena.",
        "positive": "Phenomenological Model of Wetting Charged Dielectric Surfaces and its\n  Testing with Plasma-Treated Polymer Films and Inflatable Balloons: Plasma treatment of polymer films results in their electrical charging, which\nin turn gives rise to an increase in their surface energy. The process results\nin pronounced hydrophilization of the polymer surfaces. A phenomenological\ntheory relating the change in the apparent contact angle of charged solids to\nthe surface density of the electrical charge is introduced. Partial wetting,\ninherent for polymer films, becomes possible until the threshold surface\ndensity of the electrical charge is gained. The predictions of the theory are\nillustrated by plasma-treated polymer films and inflatable latex balloons.\nDeflating the plasma treated latex balloons resulted in an essential increase\nin the surface charge density of the latex. This increase switched the wetting\nregime from partial to complete wetting. The kinetics of hydrophobic recovery\nfollows the kinetics of the electrical charge leakage from the surfaces of the\nplasma treated polymers. The characteristic time of the surface charge leakage\ncoincides with the time scale of the decay of the electret response of plasma\ntreated polymer films."
    },
    {
        "anchor": "Entropy production and rectification efficiency in colloids transport\n  along a pulsating channel: We study the current rectification of particles moving in a pulsating channel\nunder the in uence of an applied force. We have shown the existence of diferent\nrectification scenarios in which entropic and energetic effects compete. The\neffect can be quantified by means of a rectification coefficient that is\nanalyzed in terms of the force, the frequency and the diffusion coefficient.\nThe energetic cost of the motion of the particles expressed in terms of the\nentropy production depends on the importance of the entropic contribution to\nthe total force. Rectification is more important at low values of the applied\nforce when entropic effects become dominant. In this regime, the entropy\nproduction is not invariant under reversal of the applied force. The phenomenon\nobserved could be used to optimize transport in microfluidic devices or in\nbiological channels.",
        "positive": "Adsorption of Multi-block and Random Copolymer on a Solid Surface:\n  Critical Behavior and Phase Diagram: The adsorption of a single multi-block $AB$-copolymer on a solid planar\nsubstrate is investigated by means of computer simulations and scaling\nanalysis. It is shown that the problem can be mapped onto an effective\nhomopolymer adsorption problem. In particular we discuss how the critical\nadsorption energy and the fraction of adsorbed monomers depend on the block\nlength $M$ of sticking monomers $A$, and on the total length $N$ of the polymer\nchains. Also the adsorption of the random copolymers is considered and found to\nbe well described within the framework of the annealed approximation. For a\nbetter test of our theoretical prediction, two different Monte Carlo (MC)\nsimulation methods were employed: a) off-lattice dynamic bead-spring model,\nbased on the standard Metropolis algorithm (MA), and b) coarse-grained lattice\nmodel using the Pruned-enriched Rosenbluth method (PERM) which enables tests\nfor very long chains. The findings of both methods are fully consistent and in\ngood agreement with theoretical predictions."
    },
    {
        "anchor": "Active swarms on a sphere: Here we show that coupling to curvature has profound effects on collective\nmotion in active systems, leading to patterns not observed in flat space.\nBiological examples of such active motion in curved environments are numerous:\ncurvature and tissue folding are crucial during gastrulation, epithelial and\nendothelial cells move on constantly growing, curved crypts and vili in the\ngut, and the mammalian corneal epithelium grows in a steady-state vortex\npattern. On the physics side, droplets coated with actively driven microtubule\nbundles show active nematic patterns. We study a model of self-propelled\nparticles with polar alignment on a sphere. Hallmarks of these motion patterns\nare a polar vortex and a circulating band arising due to the incompatibility\nbetween spherical topology and uniform motion - a consequence of the hairy ball\ntheorem. We present analytical results showing that frustration due to\ncurvature leads to stable elastic distortions storing energy in the band.",
        "positive": "Ordering of anisotropic polarizable polymer chains on the full many-body\n  level: We study the effect of dielectric anisotropy of polymers on their equilibrium\nordering within mean-field theory but with a formalism that takes into account\nthe full n-body nature of van der Waals forces. Dielectric anisotropy within\npolymers is to be expected as the electronic properties of the polymer will\ntypically be different along the polymer than across its cross section. It is\ntherefore physically intuitive that larger charge fluctuations can be induced\nalong the chain than perpendicular to it. We show that this dielectric\nanisotropy leads to n-body interactions which can induce an isotropic--nematic\ntransition. The two body and three body components of the full van der Waals\ninteraction are extracted and it is shown how the two body term behaves like\nthe phenomenological self-aligning-pairwise nematic interaction. At the three\nbody interaction level we see that the nematic phase that is energetically\nfavorable is discotic, however on the full n-body interaction level we find\nthat the normal axial nematic phase is always the stable ordered phase. The\nn-body nature of our approach also shows that the key parameter driving the\nnematic-isotropic transition is the bare persistence length of the polymer\nchain."
    },
    {
        "anchor": "Thermally Driven Imbibition and Drainage Induced by Terraced\n  Nanostructures: Theoretical analysis and fully atomistic molecular dynamics simulations\nreveal a Brownian ratchet mechanism by which thermal fluctuations drive the net\ndisplacement of immiscible liquids confined in channels or pores with micro- or\nnanoscale dimensions. The thermally-driven displacement is induced by surface\nnanostructures with directional asymmetry and can occur against the direction\nof action of wetting or capillary forces. Mean displacement rates in molecular\ndynamics simulations are predicted via analytical solution of a Smoluchowski\ndiffusion equation for the position probability density. The proposed physical\nmechanisms and derived analytical expressions can be applied to engineer\nsurface nanostructures for controlling the dynamics of diverse wetting\nprocesses such as capillary filling, wicking, and imbibition in micro- or\nnanoscale systems.",
        "positive": "Membrane separation study for methane-hydrogen gas mixtures by molecular\n  simulations: Direct simulation results for stationary gas transport through pure silica\nzeolite membranes (MFI, LTA and DDR types) are presented using a hybrid,\nnon-equilibrium molecular dynamics simulation methodology introduced recently.\nThe intermolecular potential models for the investigated CH$_{4}$ and H$_{2}$\ngases were taken from literature. For different zeolites, the same atomic (Si\nand O) interaction parameters were used, and the membranes were constructed\naccording to their real (MFI, LTA, or DDR) crystal structures. A realistic\nnature of the applied potential parameters was tested by performing equilibrium\nadsorption simulations and by comparing the calculated results with the data of\nexperimental adsorption isotherms. The results of transport simulations carried\nout at 25$^0$C and 125$^0$C, and at 2.5, 5 or 10 bar clearly show that the\npermeation selectivities of CH$_{4}$ are higher than the corresponding\npermeability ratios of pure components, and significantly differ from the\nequilibrium selectivities in mixture adsorptions. We experienced a transport\nselectivity in favor of CH$_{4}$ in only one case. A large discrepancy between\ndifferent types of selectivity data can be attributed to dissimilar mobilities\nof the components in a membrane, their dependence on the loading of a membrane,\nand the unlike adsorption preferences of the gas molecules."
    },
    {
        "anchor": "Spatial velocity correlations in inertial systems of Active Brownian\n  Particles: Recently, it has been discovered that systems of Active Brownian particles\n(APB) at high density organise their velocities into coherent domains showing\nlarge spatial structures in the velocity field. Such a collective behavior\noccurs spontaneously, i.e. is not caused by any specific interparticle force\nfavoring the alignment of the velocities. This phenomenon was investigated in\nthe absence of thermal noise and in the overdamped regime where inertial forces\ncould be neglected. In this work, we demonstrate through numerical simulations\nand theoretical analysis that the velocity alignment is a robust property of\nABP and persists even in the presence of inertial forces and thermal\nfluctuations. We also show that a single dimensionless parameter, such as the\nP\\'eclet number customarily employed in the description of self-propelled\nparticles, is not sufficient to fully characterize such a phenomenon neither in\nthe regimes of large viscosity nor small mass. Indeed, the size of the velocity\ndomains, measured through the correlation length of the spatial velocity\ncorrelation, remains constant when the swim velocity increases while decreases\nas the rotational diffusion becomes larger. We find that the spatial velocity\ncorrelation depends on the inertia but, contrary to common belief, are\nnon-symmetrically affected by mass and inverse viscosity variations. We\nconclude that in self-propelled systems, at variance with passive systems,\nvariations of the inertial time (mass over solvent viscosity) and mass act as\nindependent control parameters. Finally, we highlight the non-thermal nature of\nthe spatial velocity correlations that are fairly insensitive both to solvent\nand active temperatures.",
        "positive": "Periodic and quasiperiodic motions of many particles falling in a\n  viscous fluid: Dynamics of regular clusters of many non-touching particles falling under\ngravity in a viscous fluid at low Reynolds number are analysed within the\npoint-particle model. Evolution of two families of particle configurations is\ndetermined: 2 or 4 regular horizontal polygons (called `rings') centred above\nor below each other. Two rings fall together and periodically oscillate. Four\nrings usually separate from each other with chaotic scattering. For hundreds of\nthousands of initial configurations, a map of the cluster lifetime is\nevaluated, where the long-lasting clusters are centred around periodic\nsolutions for the relative motions, and surrounded by regions of the chaotic\nscattering,in a similar way as it was observed by Janosi et al. (1997) for\nthree particles only. These findings suggest to consider the existence of\nperiodic orbits as a possible physical mechanism of the existence of unstable\nclusters of particles falling under gravity in a viscous fluid."
    },
    {
        "anchor": "Analytical canonical partition function of a quasi-one dimensional\n  system of hard disks: The exact canonical partition function of a hard disk system in a narrow\nquasi-one dimensional pore of given length and width is derived analytically in\nthe thermodynamic limit. As a result the many body problem is reduced to\nsolving two transcendental equations which can be easily done numerically. The\nlongitudinal and transverse pressures in the whole density range are presented\nfor three different pore widths. The transition from the solidlike zigzag to\nthe liquidlike state is found to be quite sharp in the density scale but shows\nno genuine singularity. This transition is quantitatively described by the\ndistribution of zigzag's windows through which disks exchange their positions\nacross the pore.",
        "positive": "Dynamics of quasi-static collapse process of a binary granular column: The dynamical behavior of the column that made up binary granular beads is\ninvestigated systematically by tracking the displacement of particles in the\ncollapse process. An experimental setup is first devised to control the\nquasi-static collapse of a granular column, and then observe the trajectories\nof tracer particles by using an industrial camera controlled by the image\nacquisition program. It is found that there exist two zones in column: a\nsliding region in which particles are moving in a layered structure; a static\nregion within which particles are stationary. According to this analytical\nresult, a dynamical model is developed to predict the trajectory evolution of\nparticles in the space-time. The calculating result for the trajectories of\nparticles on the selected layers is well consistent with the experimental\nobservation."
    },
    {
        "anchor": "Membrane undulations in a structured fluid: Universal dynamics at\n  intermediate length and time scales: The dynamics of membrane undulations inside a viscous solvent is governed by\ndistinctive, anomalous, power laws. Inside a viscoelastic continuous medium\nthese universal behaviors are modified by the specific bulk viscoelastic\nspectrum. Yet, in structured fluids the continuum limit is reached only beyond\na characteristic correlation length. We study the crossover to this asymptotic\nbulk dynamics. The analysis relies on a recent generalization of the\nhydrodynamic interaction in structured fluids, which shows a slow spatial decay\nof the interaction toward the bulk limit. For membranes which are weakly\ncoupled to the structured medium we find a wide crossover regime characterized\nby different, universal, dynamic power laws. We discuss various systems for\nwhich this behavior is relevant, and delineate the time regime over which it\nmay be observed.",
        "positive": "Quasichemical theory and the description of associating fluids relative\n  to a reference: Multiple bonding of a single site solute: We derive an expression for the chemical potential of an associating solute\nin a solvent relative to the value in a reference fluid using the quasichemical\norganization of the potential distribution theorem. The fraction of times the\nsolute is not associated with the solvent, the monomer fraction, is expressed\nin terms of (a) the statistics of occupancy of the solvent around the solute in\nthe reference fluid and (b) the Widom factors that arise because of turning on\nsolute-solvent association. Assuming pair-additivity, we expand the Widom\nfactor into a product of Mayer f-functions and the resulting expression is\nrearranged to reveal a form of the monomer fraction that is analogous to that\nused within the statistical associating fluid theory (SAFT). The present\nformulation avoids all graph-theoretic arguments and provides a fresh, more\nintuitive, perspective on Wertheim's theory and SAFT. Importantly, multi-body\neffects are transparently incorporated into the very foundations of the theory.\nWe illustrate the generality of the present approach by considering examples of\nmultiple solvent association to a colloid solute with bonding domains that\nrange from a small patch on the sphere, a Janus particle, and a solute whose\nentire surface is available for association."
    },
    {
        "anchor": "Stochastic dynamics of model proteins on a directed graph: A method for reconstructing the energy landscape of simple polypeptidic\nchains is described. We show that we can construct an equivalent representation\nof the energy landscape by a suitable directed graph. Its topological and\ndynamical features are shown to yield an effective estimate of the time scales\nassociated with the folding and with the equilibration processes. This\nconclusion is drawn by comparing molecular dynamics simulations at constant\ntemperature with the dynamics on the graph, defined by a temperature dependent\nMarkov process. The main advantage of the graph representation is that its\ndynamics can be naturally renormalized by collecting nodes into \"hubs\", while\nredefining their connectivity. We show that both topological and dynamical\nproperties are preserved by the renormalization procedure. Moreover, we obtain\nclear indications that the heteropolymers exhibit common topological\nproperties, at variance with the homopolymer, whose peculiar graph structure\nstems from its spatial homogeneity. In order to obtain a clear distinction\nbetween a \"fast folder\" and a \"slow folder\" in the heteropolymers one has to\nlook at kinetic features of the directed graph. We find that the average time\nneeded to the fast folder for reaching its native configuration is two orders\nof magnitude smaller than its equilibration time, while for the bad folder\nthese time scales are comparable. Accordingly, we can conclude that the\nstrategy described in this paper can be successfully applied also to more\nrealistic models, by studying their renormalized dynamics on the directed\ngraph, rather than performing lengthy molecular dynamics simulations.",
        "positive": "Electric properties of supercooled water contained in cylindrical\n  nanopores: The paper provides data on measuring electrical properties of supercooled\nwater in nanoporous silica MCM-41 with 3.5 nm diameter cylindrical pores, using\nthe methods of dielectric spectroscopy and measuring proper electrical\nfluctuations at low frequencies. Occurrence of non-linear media properties at\nthe temperatures below -35 C was determined, which was revealed in the form of\nregistered cell capacity dependence on voltage amplitude in it, as well as\nnoise increase close to -40 C. The effects observed are supposed to be related\nto the earlier predicted ferroelectric phase transition."
    },
    {
        "anchor": "On the decay of the pair correlation function and the line of vanishing\n  excess isothermal compressibility in simple fluids: We re-visit the competition between attractive and repulsive interparticle\nforces in simple fluids and how this governs and connects the macroscopic phase\nbehavior and structural properties as manifest in pair correlation functions.\nWe focus on the asymptotic decay of the total correlation function $h(r)$ which\nis, in turn, controlled by the form of the pair direct correlation function\n$c(r)$. The decay of $r h(r)$ to zero can be either exponential (monotonic) if\nattraction dominates repulsion and exponentially damped oscillatory otherwise.\nThe Fisher-Widom (FW) line separates the phase diagram into two regions\ncharacterized by the two different types of asymptotic decay. We show that\nthere is a new and physically intuitive thermodynamic criterion which\napproximates well the actual FW line. This new criterion defines a line where\nthe isothermal compressibility takes its ideal gas value\n$\\chi_T=\\chi_T^\\text{id}$. We test our hypothesis by considering four commonly\nused models for simple fluids. In all cases the new criterion yields a line in\nthe phase diagram that is close to the actual FW line for the thermodynamic\nstate points that are most relevant. We also investigate (Widom) lines of\nmaximal correlation length, emphasizing the importance of distinguishing\nbetween the true and Ornstein-Zernike correlation lengths",
        "positive": "Rectified Rotational Dynamics of Mobile Inclusions in Two-Dimensional\n  Active Nematics: We investigate the dynamics of mobile inclusions embedded in 2D active\nnematics. The interplay between the inclusion shape, the boundary-induced\nnematic order, and the autonomous flow powers the inclusion motion. Disks and\nachiral gears exhibit unbiased rotational motion, but with distinct dynamics.\nIn comparison, chiral gear-shaped inclusions exhibit long-term rectified\nrotation, which is correlated with dynamics and polarization of nearby +1/2\ntopological defects. The chirality of defect polarities and the active nematic\ntexture around the inclusion correlate with the inclusion's instantaneous\nrotationr ate. Inclusions provide a promising tool for probing the rheological\nproperties of active nematics and extracting ordered motion from the inherently\nchaotic motion of active nematics."
    },
    {
        "anchor": "Geometric Predictors of Knotted and Linked Arcs: Inspired by how certain proteins \"sense\" knots and entanglements in DNA\nmolecules, here we ask if there exist local geometric features that may be used\nas a read-out of the underlying topology of generic polymers. We perform\nmolecular simulations of knotted and linked semiflexbile polymers and study\nfour geometric measures to predict topological entanglements: local curvature,\nlocal density, local 1D writhe and non-local 3D writhe. We discover that local\ncurvature is a poor predictor of entanglements. In contrast, segments with\nmaximum local density or writhe correlate as much as 90% of the time with the\nshortest knotted and linked arcs. We find that this accuracy is preserved\nacross different knot types and also under significant spherical confinement,\nwhich is known to delocalise essential crossings in knotted polymers. We\nfurther discover that non-local 3D writhe is the best geometric read-out of\nknot location. Finally, we discuss how these geometric features may be used to\ncomputationally analyse entanglements in generic polymer melts and gels.",
        "positive": "Dissipation induced transitions in two dimensional elastic membranes: Stochastic thermodynamics provides a useful set of tools to analyze and\nconstrain the behavior of far from equilibrium systems. In this paper, we\nreport an application of ideas from stochastic thermodynamics to the problem of\nmembrane growth. Non-equilibrium forcing of the membrane can cause it to buckle\nand undergo a morphological transformation. We show how ideas from stochastic\nthermodynamics, in particular the recently derived thermodynamic uncertainty\nrelations, can be used to phenomenologically describe and constrain the\nparameters required to excite morphological changes during a non-equilibrium\ngrowth process."
    },
    {
        "anchor": "Characterizing the Rheology of Fluidized Granular Matter: In this study we characterize the rheology of fluidized granular matter\nsubject to secondary forcing. Our approach consists of first fluidizing\ngranular matter in a drum half filled with grains via simple rotation, and then\nsuperimposing oscillatory shear perpendicular to the downhill flow direction.\nThe response of the system is mostly linear, with a phase lag between the grain\nmotion and the oscillatory forcing. The rheology of the system can be well\ncharacterize by the GDR-Midi model if the system is forced with slow\noscillations. The model breaks down when the forcing timescale becomes\ncomparable to characteristic time for energy dissipation in the flow.",
        "positive": "Pinning Susceptibility: The effect of dilute, quenched disorder on\n  jamming: We study the effect of dilute pinning on the jamming transition. Pinning\nreduces the average contact number needed to jam unpinned particles and shifts\nthe jamming threshold to lower densities, leading to a pinning susceptibility,\n$\\chi_p$. Our main results are that this susceptibility obeys scaling form and\ndiverges in the thermodynamic limit as $\\chi_p \\propto |\\phi -\n\\phi_c^\\infty|^{-\\gamma_p}$ where $\\phi_c^\\infty$ is the jamming threshold in\nthe absence of pins. Finite-size scaling arguments yield these values with\nassociated statistical (systematic) errors $\\gamma_p = 1.018 \\pm 0.026 (0.291)\n$ in $d=2$ and $\\gamma_p =1.534 \\pm 0.120 (0.822)$ in $d=3$. Logarithmic\ncorrections raise the exponent in $d=2$ to close to the $d=3$ value, although\nthe systematic errors are very large."
    },
    {
        "anchor": "Recent Progress in Molecular Simulation of Aqueous Electrolytes: Force\n  Fields, Chemical Potentials and Solubility: Although aqueous electrolytes are among the most important solutions, the\nmolecular simulation of their intertwined properties of chemical potentials,\nsolubility and activity coefficients has remained a challenging problem, and\nhas attracted considerable recent interest. In this perspectives review, we\nfocus on the simplest case of aqueous sodium chloride at ambient conditions and\ndiscuss the two main factors that have impeded progress. The first is lack of\nconsensus with respect to the appropriate methodology for force field (FF)\ndevelopment. We examine how most commonly used FFs have been developed, and\nemphasize the importance of distinguishing between \"Training Set Properties\"\nused to fit the FF parameters, and \"Test Set Properties\", which are pure\npredictions of additional properties. The second is disagreement among\nsolubility results obtained, even using identical FFs and thermodynamic\nconditions. Solubility calculations have been approached using both\nthermodynamic--based methods and direct molecular dynamics--based methods\nimplementing coexisting solution and solid phases. Although convergence has\nbeen very recently achieved among results based on the former approach, there\nis as yet no general agreement with simulation results based on the latter\nmethodology. We also propose a new method to directly calculate the electrolyte\nstandard chemical potential in the Henry-Law ideality model. We conclude by\nmaking recommendations for calculating solubility, chemical potentials and\nactivity coefficients, and outline a potential path for future progress.",
        "positive": "Phase and glass transitions in short-range central potential model\n  systems: The case of C60: Extensive molecular dynamics simulations show that a short-range central\npotential, suited to model C60, undergoes a high temperature transition to a\nglassy phase characterized by the positional disorder of the constituent\nparticles. Crystallization, melting and sublimation, which also take place\nduring the simulation runs, are illustrated in detail. It turns out that\nvitrification and the mentioned phase transitions occur when the packing\nfraction of the system - defined in terms of an effective hard-core diameter -\nequals that of hard spheres at their own glass and melting transition,\nrespectively. A close analogy also emerges between our findings and recent mode\ncoupling theory calculations of structural arrest lines in a similar model of\nprotein solutions. We argue that the conclusions of the present study might\nhold for a wide class of potentials currently employed to mimic interactions in\ncomplex fluids (some of which of biological interest), suggesting how to\nachieve at least qualitative predictions of vitrification and crystallization\nin those systems."
    },
    {
        "anchor": "Stiff Polymers, Foams and Fiber Networks: We study the elasticity of fibrous materials composed of generalized stiff\npolymers. It is shown that in contrast to cellular foam-like structures affine\nstrain fields are generically unstable. Instead, a subtle interplay between the\narchitecture of the network and the elastic properties of its building blocks\nleads to intriguing mechanical properties with intermediate asymptotic scaling\nregimes. We present exhaustive numerical studies based on a finite element\nmethod complemented by scaling arguments.",
        "positive": "Excess Vibrational Density of States and the Brittle to Ductile\n  Transition in Crystalline and Amorphous Solids: The conditions which determine whether a material behaves in a brittle or\nductile fashion on mechanical loading are still elusive and comprise a topic of\nactive research among materials physicists and engineers. In this study, we\npresent results of {\\em in silico} mechanical deformation experiments from two\nvery different model solids in two and three dimensions. The first consists of\nparticles interacting with isotropic potentials and the other has strongly\ndirection dependent interactions. We show that in both cases, the excess\nvibrational density of states is the fundamental quantity which characterises\nthe ductility of the material. Our results can be checked using careful\nexperiments on colloidal solids."
    },
    {
        "anchor": "A new restriction for initially stressed elastic solids: We introduce a fundamental restriction on the strain energy function and\nstress tensor for initially stressed elastic solids. The restriction applies to\nstrain energy functions $W$ that are explicit functions of the elastic\ndeformation gradient $\\mathbf{F}$ and initial stress $\\boldsymbol \\tau$, i.e.\n$W:= W(\\mathbf F, \\boldsymbol \\tau)$. The restriction is a consequence of\nenergy conservation and ensures that the predicted stress and strain energy do\nnot depend upon an arbitrary choice of reference configuration. We call this\nrestriction: initial stress reference independence (ISRI). It transpires that\nalmost all strain energy functions found in the literature do not satisfy ISRI,\nand may therefore lead to unphysical behaviour, which we illustrate via a\nsimple example. To remedy this shortcoming we derive three strain energy\nfunctions that do satisfy the restriction. We also show that using initial\nstrain (often from a virtual configuration) to model initial stress leads to\nstrain energy functions that automatically satisfy ISRI. Finally, we reach the\nfollowing important result: ISRI reduces the number of unknowns of the linear\nstress tensor of initially stressed solids. This new way of reducing the linear\nstress may open new pathways for the non-destructive determination of initial\nstresses via ultrasonic experiments, among others.",
        "positive": "Simulating squirmers with multiparticle collision dynamics: Multiparticle collision dynamics is a modern coarse-grained simulation\ntechnique to treat the hydrodynamics of Newtonian fluids by solving the\nNavier-Stokes equations. Naturally, it also includes thermal noise. Initially\nit has been applied extensively to spherical colloids or bead-spring polymers\nimmersed in a fluid. Here, we review and discuss the use of multiparticle\ncollision dynamics for studying the motion of spherical model microswimmers\ncalled squirmers moving in viscous fluids."
    },
    {
        "anchor": "Phase behaviour of charged colloidal sphere dispersions with added\n  polymer chains: We study the stability of mixtures of highly screened repulsive charged\nspheres and non-adsorbing ideal polymer chains in a common solvent using free\nvolume theory. The effective interaction between charged colloids in an aqueous\nsalt solution is described by a screened-Coulomb pair potential, which\nsupplements the pure hard-sphere interaction. The ideal polymer chains are\ntreated as spheres that are excluded from the colloids by a hard-core\ninteraction, whereas the interaction between two ideal chains is set to zero.\nIn addition, we investigate the phase behaviour of charged colloid-polymer\nmixtures in computer simulations, using the two-body (Asakura-Oosawa pair\npotential) approximation to the effective one-component Hamiltonian of the\ncharged colloids. Both our results obtained from simulations and from free\nvolume theory show similar trends. We find that the screened-Coulomb repulsion\ncounteracts the effect of the effective polymer-mediated attraction. For\nmixtures of small polymers and relatively large charged colloidal spheres, the\nfluid-crystal transition shifts to significantly larger polymer concentrations\nwith increasing range of the screened-Coulomb repulsion. For relatively large\npolymers, the effect of the screened-Coulomb repulsion is weaker. The resulting\nfluid-fluid binodal is only slightly shifted towards larger polymer\nconcentrations upon increasing the range of the screened-Coulomb repulsion. In\nconclusion, our results show that the miscibility of dispersions containing\ncharged colloids and neutral non-adsorbing polymers increases, upon increasing\nthe range of the screened-Coulomb repulsion, or upon lowering the salt\nconcentration, especially when the polymers are small compared to the colloids.",
        "positive": "State-and-rate friction in contact-line dynamics: In order to probe the dynamics of contact-line motion, we study the\nmacroscopic properties of sessile drops deposited on and then aspirated from\ncarefully prepared horizontal surfaces. By measuring the contact angle and drop\nwidth simultaneously during droplet removal, we determine the changes in the\nshape of the drop as it depins and recedes. Our data indicate that there is a\nforce which opposes the motion of the contact line that depends both on the\namount of time that the drop has been in contact with the surface and on the\nwithdrawal rate. For water on silanized glass, we capture the experimentally\nobserved behavior with an overdamped dynamical model of contact-line motion in\nwhich the phenomenological drag coefficient and the assumed equilibrium contact\nangle are the only inputs. For other liquid/substrate pairs, the observed\ncontact-line motion suggests that a maximum static friction force is important\nin addition to damping. The dependence on time of contact and withdrawal rate,\nreminiscent of rate-and-state friction between solid surfaces, is qualitatively\nconsistent across three substrate-liquid pairs."
    },
    {
        "anchor": "Stability of additive-free water-in-oil emulsions: We calculate ion distributions near a planar oil-water interface within\nnon-linear Poisson-Boltzmann theory, taking into account the Born self-energy\nof the ions in the two media. For unequal self-energies of cations and anions,\na spontaneous charge separation is found such that the water and oil phase\nbecome oppositely charged, in slabs with a typical thickness of the Debye\nscreening length in the two media. From the analytical solutions, the\ncorresponding interfacial charge density and the contribution to the\ninterfacial tension is derived, together with an estimate for the\nYukawa-potential between two spherical water droplets in oil. The parameter\nregime is explored where the plasma coupling parameter exceeds the\ncrystallization threshold, i.e. where the droplets are expected to form\ncrystalline structures due to a strong Yukawa repulsion, as recently observed\nexperimentally. Extensions of the theory that we discuss briefly include\nnumerical calculations on spherical water droplets in oil, and analytical\ncalculations of the linear PB-equation for a finite oil-water interfacial\nwidth.",
        "positive": "Bending to kinetic energy transfer in adhesive peel front\n  micro-instability: We report an extensive experimental study of a detachment front dynamics\ninstability, appearing at microscopic scales during the peeling of adhesive\ntapes. The amplitude of this instability scales with its period as\n$A_{\\text{mss}} \\propto T_{\\text{mss}}^{1/3}$, with a pre-factor evolving\nslightly with the peel angle $\\theta$, and increasing systematically with the\nbending modulus $B$ of the tape backing. Establishing a local energy budget of\nthe detachment process during one period of this micro-instability, our\ntheoretical model shows that the elastic bending energy stored in the portion\nof tape to be peeled is converted into kinetic energy, providing a quantitative\ndescription of the experimental scaling law."
    },
    {
        "anchor": "Fast Diffusion of Long Guest Rods in a Lamellar Phase of Short Host\n  Particles: We investigate the dynamic behavior of long guest rod-like particles immersed\nin liquid crystalline phases formed by shorter host rods, tracking both guest\nand host particles by fluorescence microscopy. Counter-intuitively, we evidence\nthat long rods diffuse faster than short rods forming the one-dimensional\nordered smectic-A phase. This results from the larger and non-commensurate size\nof the guest particles as compared to the wavelength of the energy landscape\nset by the lamellar stack of liquid slabs. The long guest particles are also\nshown to be still mobile in the crystalline smectic-B phase, as they generate\ntheir own voids in the adjacent layers.",
        "positive": "Acoustic emissions of nearly steady and uniform granular flows: a proxy\n  for flow dynamics and velocity fluctuations: The seismic waves emitted during granular flows are generated by different\nsources: high frequencies by inter-particle shocks and low frequencies by\nglobal motion and large scale deformation. To unravel these different\nmechanisms, an experimental study has been performed on the seismic waves\nemitted by dry quasi steady granular flows. The emitted seismic waves were\nrecorded using shock accelerometers and the flow dynamics were captured with a\nfast camera. The mechanical characteristics of the particle shocks were\nanalyzed, along with the duration between shocks and the correlations in the\nparticle motion. The high-frequency seismic waves (1-50 kHz) were found to\noriginate from particle shocks and waves trapped in the flowing layer. The\nlow-frequency waves (20-60 Hz) were generated by the oscillations of the\nparticles along their trajectories, i.e. from cycles of dilation/compression\nduring the shear. The profiles of granular temperature (i.e. the square of\nparticle velocity fluctuations) and average velocity were measured and related\nto the average properties of the flow as well as to the slope angle and flow\nthickness. These profiles were then used in a simple steady granular flow model\nto predict the radiated seismic energy and the energetic efficiency, i.e. the\nfraction of the flow potential energy converted to seismic energy. Scaling laws\nrelating the seismic power, the shear strain rate and the inertial number were\nderived. In particular, the emitted seismic power is proportional to the\ngranular temperature, which is also related to the mean flow velocity."
    },
    {
        "anchor": "Spontaneous imbibition in porous media: from pore scale to Darcy scale: Spontaneous imbibition has been receiving much attention due to its\nsignificance in many subsurface and industrial applications. Unveiling\npore-scale wetting dynamics, and particularly its upscaling to the Darcy scale\nare still unresolved. In this work, we conduct image-based pore-network\nmodeling of cocurrent spontaneous imbibition and the corresponding quasi-static\nimbibition, in homogeneous sintered glass beads as well as heterogeneous\nEstaillades. A wide range of viscosity ratios and wettability conditions are\ntaken into account. Based on our pore-scale results, we show the influence of\npore-scale heterogeneity on imbibition dynamics and nonwetting entrapment. We\nelucidate different pore-filling mechanisms in imbibition, which helps us\nunderstand wetting dynamics. Most importantly, we develop a non-equilibrium\nmodel for relative permeability of the wetting phase, which adequately\nincorporates wetting dynamics. This is crucial to the final goal of developing\na two-phase imbibition model with measurable material properties such as\ncapillary pressure and relative permeability. Finally, we propose some future\nwork on both numerical and experimental verifications of the developed\nnon-equilibrium permeability model.",
        "positive": "Rational-function approximation for fluids interacting via piece-wise\n  constant potentials: The structural properties of fluids whose molecules interact via potentials\nwith a hard-core plus n piece-wise constant sections of different widths and\nheights are derived using a (semi-analytical) rational-function approximation\nmethod. The results are illustrated for the cases of a square-shoulder plus\nsquare-well potential and a shifted square-well potential and compared both\nwith simulation data and with those that follow from the (numerical) solutions\nof the Percus-Yevick integral equation."
    },
    {
        "anchor": "Variational methods and deep Ritz method for active elastic solids: Variational methods have been widely used in soft matter physics for both\nstatic and dynamic problems. These methods are mostly based on two variational\nprinciples: the variational principle of minimum free energy (MFEVP) and\nOnsager's variational principle (OVP). Our interests lie in the applications of\nthese variational methods to active matter physics. In our former work [Soft\nMatter, 2021, 17, 3634], we have explored the applications of OVP-based\nvariational methods for the modeling of active matter dynamics. In the present\nwork, we explore variational (or energy) methods that are based on MFEVP for\nstatic problems in active elastic solids. We show that MFEVP can be used not\nonly to derive equilibrium equations, but also to develop approximate solution\nmethods, such as Ritz method, for active solid statics. Moreover, the power of\nRitz-type method can be further enhanced using deep learning methods if we use\ndeep neural networks to construct the trial solutions of the variational\nproblems. We then apply these variational methods and the deep Ritz method to\nstudy the spontaneous bending and contraction of a thin active circular plate\nthat is induced by internal asymmetric active contraction. The circular plate\nis found to be bent towards its contracting side. The study of such a simple\ntoy system gives implications for understanding the morphogenesis of solid-like\nconfluent cell monolayers. In addition, we introduce a so-called activogravity\nlength to characterize the importance of gravitational forces relative to\ninternal active contraction in driving the bending of the active plate. When\nthe lateral plate dimension is larger than the activogravity length (about 100\nmicron), gravitational forces become important. Such gravitaxis behaviors at\nmulticellular scales may play significant roles in the morphogenesis and in the\nup-down symmetry broken during tissue development.",
        "positive": "Elastostatics of star-polygon tile-based architectured planar lattices: A panoptic view of architectured planar lattices based on star-polygon\ntilings was developed. Four star-polygon-based lattice sub-families, formed of\nsystematically arranged triangles, squares, or hexagons, were investigated\nnumerically and experimentally. Finite-element-based homogenization allowed\ncomputation of Poisson's ratio, elastic modulus, shear modulus, and planar bulk\nmodulus. A comprehensive understanding of the range of properties and\nmicromechanical deformation mechanisms was developed. Adjusting the\nstar-polygon angle achieved an over 250-fold range in elastic modulus, over a\n10-fold range in density, and a range of $-0.919$ to $+0.988$ for Poisson's\nratio. Additively manufactured lattices, achieved by novel printing strategies,\nshowed good agreement in properties. Parametric additive manufacturing\nprocedures for all lattices are available on\n\\url{www.fullcontrol.xyz/#/models/1d3528}. Three of the four sub-families\nexhibited in-plane elastic isotropy. One showed high stiffness with auxeticity\nat low density and a primarily axial deformation mode as opposed to bending\ndeformation for the other three lattices. The range of achievable properties,\ndemonstrated with property maps, proves the extension of the conventional\nmaterial-property space. Lattice metamaterials with Triangle-Triangle, Kagome,\nHexagonal, Square, Truncated Archimedean, Triangular, and Truncated Hexagonal\ntopologies have been studied in the literature individually. Here, it is shown\nthat these structures belong to the presented overarching lattice family."
    },
    {
        "anchor": "Coexistence of Scale-Invariant States in Incompressible Elastomers: Cavitation and sulcification of soft elastomers are two examples of\nthresholdless, nonlinear instabilities that evade detection by linearization. I\nshow that the onset of such instabilities can be understood as a kind of phase\ncoexistence between multiple scale-invariant states, and I constructively\nenumerate the possible scale-invariant states of incompressible rubber in two\ndimensions. Whereas true phases (like the affine deformations of rubber) are\nhomogeneous, the alternatives are inhomogeneous. In terms of the thermodynamics\nof solids, both classes of states must generally be given equal consideration.",
        "positive": "Tensor decomposition for modified quasi-linear viscoelastic models:\n  towards a fully nonlinear theory: We discuss the decomposition of the tensorial relaxation function for\nisotropic and transversely isotropic Modified Quasi-Linear Viscoelastic models.\nWe show how to formulate the constitutive equation by using a convenient\ndecomposition of the relaxation tensor into scalar components and tensorial\nbases. We show that the bases must be symmetrically additive, i.e they must sum\nup to the symmetric fourth-order identity tensor. This is a fundamental\nproperty both for isotropic and anisotropic bases that ensures the constitutive\nequation is consistent with the elastic limit. We provide two robust methods to\nobtain such bases. Furthermore, we show that, in the transversely isotropic\ncase, the bases are naturally deformation-dependent for deformation modes that\ninduce rotation or stretching of the fibres. Therefore, the Modified\nQuasi-Linear Viscoelastic framework allows to capture the non-linear phenomenon\nof strain-dependent relaxation, which has always been a criticised limitation\nof the original Quasi-Linear Viscoelastic theory. We illustrate this intrinsic\nnon-linear feature, unique to the Modified Quasi-Linear Viscoelastic model,\nwith two examples (uni-axial extension and perpendicular shear)."
    },
    {
        "anchor": "Une br\u00e8ve introduction \u00e0 la mati\u00e8re molle: A short introduction to soft condensed matter (polymers, colloids,\nsurfactants) is presented, with particular emphasis to recent progres and\napplications of small angle scattering. The text is in French.",
        "positive": "Glassy states and microphase separation in cross-linked homopolymer\n  blends: The physical properties of blends of distinct homopolymers, cross-linked\nbeyond the gelation point, are addressed via a Landau approach involving a pair\nof coupled order-parameter fields: one describing vulcanisation, the other\ndescribing local phase separation. Thermal concentration fluctuations, present\nat the time of cross-linking, are frozen in by cross-linking, and the structure\nof the resulting glassy fluctuations is analysed at the Gaussian level in\nvarious regimes, determined by the relative values of certain physical\nlength-scales. The enhancement, due to gelation, of the stability of the blend\nwith respect to demixing is also analysed. Beyond the corresponding stability\nlimit, gelation prevents complete demixing, replacing it by microphase\nseparation, which occurs up to a length-scale set by the rigidity of the\nnetwork, as a simple variational scheme reveals."
    },
    {
        "anchor": "Universal Anisotropy in Force Networks under Shear: Scaling properties of patterns formed by large contact forces are studied as\na function of the applied shear stress, in two-dimensional static packings\ngenerated from the force network ensemble. An anisotropic finite-size-scaling\nanalysis shows that the applied shear does not affect the universal scaling\nproperties of these patterns, but simply induces different length scales in the\nprincipal directions of the macroscopic stress tensor. The ratio of these\nlength scales quantifies the anisotropy of the force networks, and is found not\nto depend on the details of the underlying contact network, in contrast with\nother properties such as the yield stress.",
        "positive": "Calculation of the Phase Field of a Vortex Pair on the Surface of a\n  Multiplly Connected Substrate: The vortex pair phase field is calculated, through a solution of the Laplace\nequation, for a superfluid film adsorbed on the surface of a model 3D connected\nporous medium. A number of different vortex-antivortex pair configurations are\nconsidered as functions of the porosity or an aspect ratio of the model porous\nstructure. The calculated results give the energy of a pair for motion of the\nvortex cores around a pore or a solid rod as well as for the string\nconfiguration corresponding to a linear separation of the vortex pair through\nthe porous medium."
    },
    {
        "anchor": "Correlation between Fragility and the Arrhenius Crossover Phenomenon in\n  Metallic, Molecular, and Network Liquids: We report the observation of a distinct correlation between the kinetic\nfragility index $m$ and the reduced Arrhenius crossover temperature $\\theta_A =\nT_A/T_g$ in various glass-forming liquids, identifying three distinguishable\ngroups. In particular, for 11 glass-forming metallic liquids, we universally\nobserve a crossover in the mean diffusion coefficient from high-temperature\nArrhenius to low-temperature super-Arrhenius behavior at approximately\n$\\theta_A \\approx 2$ which is in the stable liquid phases. In contrast, for\nfragile molecular liquids, this crossover occurs at much lower $\\theta_A\n\\approx 1.4$ and usually in their supercooled states. The $\\theta_A$ values for\nstrong network liquids spans a wide range higher than 2. Intriguingly, the\nhigh-temperature activation barrier $E_\\infty$ is universally found to be $\\sim\n11\\ k_B T_g$ and uncorrelated with the fragility or the reduced crossover\ntemperature $\\theta_A$ for metallic and molecular liquids. These observations\nprovide a way to estimate the low-temperature glassy characteristics ($T_g$ and\n$m$) from the high-temperature liquid quantities ($E_\\infty$ and $\\theta_A$).",
        "positive": "Poisson-Boltzmann thermodynamics of counter-ions confined by curved hard\n  walls: We consider a set of identical mobile point-like charges (counter-ions)\nconfined to a domain with curved hard walls carrying a uniform fixed surface\ncharge density, the system as a whole being electroneutral. Three domain\ngeometries are considered: a pair of parallel plates, the cylinder and the\nsphere. The particle system in thermal equilibrium is assumed to be described\nby the nonlinear Poisson-Boltzmann theory. While the effectively 1D plates and\nthe 2D cylinder have already been solved, the 3D sphere problem is not\nintegrable. It is shown that the contact density of particles at the charged\nsurface is determined by a first-order Abel differential equation of the second\nkind which is a counterpart of Enig's equation in the critical theory of\ngravitation and combustion/explosion. This equation enables us to construct the\nexact series solutions of the contact density in the regions of small and large\nsurface charge densities. The formalism provides, within the mean-field\nPoisson-Boltzmann framework, the complete thermodynamics of counter-ions inside\na charged sphere (salt-free system)."
    },
    {
        "anchor": "Interactions of distinct quadrupolar nematic colloids: The effective interaction between spherical colloids in nematic liquid\ncrystals is investigated in the framework of the Landau-de Gennes theory. The\ncolloids differ through their interaction with the nematic. While both\nparticles induce quadrupolar far-field distortions in the nematic matrix, with\nunlike quadrupole moments, one favours homeotropic and the other degenerate\nplanar anchoring of the nematic director. In the strong anchoring regime the\ncolloids with homeotropic anchoring are accompanied by an equatorial\ndisclination line defect, known as \"Saturn-ring\", while the colloids with\ndegenerate planar anchoring nucleate a pair of antipodal surface defects,\ncalled \"Boojums\". In the linear (large-distance) regime the colloidal\ninteractions are of the quadrupolar type, where the quadrupoles have opposite\nsigns. These are attractive when the colloids are aligned either parallel or\nperpendicular to the far-field director. At short distance, non-linear effects\nincluding \"direct\" interactions between defects give rise to a repulsion\nbetween the particles, which prevents them from touching. This finding supports\nthe stability of nematic colloidal square crystallites the assembly of which\nhas been reported recently.",
        "positive": "Swimming with a friend at low Reynolds number: We investigate the hydrodynamic interactions between microorganisms swimming\nat low Reynolds number. By considering simple model swimmers, and combining\nanalytic and numerical approaches, we investigate the time-averaged flow field\naround a swimmer. At short distances the swimmer behaves like a pump. At large\ndistances the velocity field depends on whether the swimming stroke is\ninvariant under a combined time-reversal and parity transformation. We then\nconsider two swimmers and find that the interaction between them consists of\ntwo parts; a dead term, independent of the motion of the second swimmer, which\ntakes the expected dipolar form and a live term resulting from the simultaneous\nswimming action of both swimmers which does not. We argue that, in general, the\nlatter dominates. The swimmer--swimmer interaction is a complicated function of\ntheir relative displacement, orientation and phase, leading to motion that can\nbe attractive, repulsive or oscillatory."
    },
    {
        "anchor": "On the onset of slip at adhesive elastic interfaces: The transition from static to dynamic friction when an elastic body is slid\nover another is now known to result from the motion of interface rupture\nfronts. These fronts may be either crack-like or pulse-like, with the latter\ninvolving reattachment in the wake of the front. How and why these fronts occur\nremains a subject of active theoretical and experimental investigation, given\nits wide ranging implications for a range of problems in tribology. In this\nwork, we investigate this question using an elastic lattice-network\nrepresentation; bulk and interface bonds are simulated to deform and, in the\nlatter case, break and reform dynamically in response to an applied remote\ndisplacement. We find that, contrary to the oft-cited rigid body scenario with\nCoulomb-type friction laws, the type of rupture front observed depends\nintimately on the location of the applied boundary condition. Depending on\nwhether the sliding solid is pulled, pushed or sheared -- all equivalent\napplications in the rigid case -- distinct interface rupture modes can occur.\nWe quantify these rupture modes, evaluate the interface stresses that lead to\ntheir formation, and and study their subsequent propagation dynamics. A strong\nanalogy between the sliding friction problem and mode II fracture emerges from\nour results, with attendant wave speeds ranging from slow to Rayleigh. We\ndiscuss how these fronts mediate interface motion and implications for the\ngeneral transition mechanism from static to dynamic friction.",
        "positive": "Distribution Functionals for Hard Particles in N Dimensions: The current article completes our investigation of the hard-particle\ninteraction by determining their distribution functionals. Beginning with a\nshort review of the perturbation expansion of the free-energy functional, we\nderive two representations of the correlation functionals in rooted and\nunrooted Mayer diagrams, which are related by a functional derivative. This map\nallows to transfer the mathematical methods, developed previously for unrooted\ndiagrams, to the current representation in rooted graphs. Translating then the\nMayer to Ree-Hoover diagrams and determining their automorphism groups, yields\nthe generic functional for all r-particle distributions. From this we derive\nthe examples of 2- and 3-particle correlations up to four intersection centers\nand show that already the leading order reproduces the Wertheim, Thiele, Baxter\nsolution for the contact probability of spheres. Another calculation shows the\nfailure of the Kirkwood superposition approximation for any r-particle\ncorrelation."
    },
    {
        "anchor": "Dispersion of biased swimming microorganisms in a fluid flowing through\n  a tube: Classical Taylor-Aris dispersion theory is extended to describe the transport\nof suspensions of self-propelled dipolar cells in a tubular flow. General\nexpressions for the mean drift and effective diffusivity are determined exactly\nin terms of axial moments, and compared with an approximation a la Taylor. As\nin the Taylor-Aris case, the skewness of a finite distribution of biased\nswimming cells vanishes at long times. The general expressions can be applied\nto particular models of swimming microorganisms, and thus be used to predict\nswimming drift and diffusion in tubular bioreactors, and to elucidate competing\nunbounded swimming drift and diffusion descriptions. Here, specific examples\nare presented for gyrotactic swimming algae.",
        "positive": "Nanoscale surface relaxation of a membrane stack: Recent measurements of the short-wavelength (~ 1--100 nm) fluctuations in\nstacks of lipid membranes have revealed two distinct relaxations: a fast one\n(decay rate of ~ 0.1 ns^{-1}), which fits the known baroclinic mode of bulk\nlamellar phases, and a slower one (~ 1--10 \\mu s^{-1}) of unknown origin. We\nshow that the latter is accounted for by an overdamped capillary mode,\ndepending on the surface tension of the stack and its anisotropic viscosity. We\nthereby demonstrate how the dynamic surface tension of membrane stacks could be\nextracted from such measurements."
    },
    {
        "anchor": "3D-Printed Surface Architecture Enhancing Superhydrophobicity and\n  Viscous Droplet Repellency: Macro-textured superhydrophobic surfaces can reduce droplet-substrate contact\ntimes of impacting water droplets, however, surface designs with similar\nperformance for significantly more viscous liquids are missing, despite their\nimportance in nature and technology such as for chemical shielding, food\nstaining repellency, and supercooled (viscous) water droplet removal in\nanti-icing applications. Here, we introduce a deterministic, controllable and\nup-scalable method to fabricate superhydrophobic surfaces with a 3D-printed\narchitecture, combining arrays of alternating surface protrusions and\nindentations. We show a more than threefold contact time reduction of impacting\nviscous droplets up to a fluid viscosity of 3.7mPa s, which equals 3.7 times\nthe viscosity of water at room temperature, covering the viscosity of many\nchemicals and supercooled water. Based on the combined consideration of the\nfluid flow within and the simultaneous droplet dynamics above the texture, we\nrecommend future pathways to rationally architecture such surfaces, all\nrealizable with the methodology presented here.",
        "positive": "Evolution of local relaxed states and the modelling of viscoelastic\n  fluids: We introduce a class of continuum mechanical models aimed at describing the\nbehavior of viscoelastic fluids by incorporating concepts originated in the\ntheory of solid plasticity. Within this class, even a simple model with\nconstant material parameters is able to qualitatively reproduce a number of\nexperimental observations in both simple shear and extensional flows, including\nlinear viscoelastic properties, the rate dependence of steady-state material\nfunctions, the stress overshoot in incipient shear flows, and the difference in\nshear and extensional rheological curves. Furthermore, by allowing the\nrelaxation time of the model to depend on the total strain, we can reproduce\nsome experimental observations of the non-attainability of steady flows in\nuniaxial extension, and link this to a concept of polymeric jamming or\neffective solidification. Remarkably, this modelling framework helps in\nunderstanding the interplay between different mechanisms that may compete in\ndetermining the rheology of non-Newtonian materials."
    },
    {
        "anchor": "Hyperbranched polymer stars with Gaussian chain statistics revisited: Conformational properties of regular dendrimers and more general\nhyperbranched polymer stars with Gaussian statistics for the spacer chains\nbetween branching points are revisited numerically. We investigate the scaling\nfor asymptotically long chains especially for fractal dimensions $d_f = 3$\n(marginally compact) and $d_f = 2.5$ (diffusion limited aggregation). Power-law\nstars obtained by imposing the number of additional arms per generation are\ncompared to truly self-similar stars. We discuss effects of weak excluded\nvolume interactions and sketch the regime where the Gaussian approximation\nshould hold in dense solutions and melts for sufficiently large spacer chains.",
        "positive": "Betweenness Centrality as Predictor for Forces in Granular Packings: A load applied to a jammed frictional granular system will be localized into\na network of force chains making inter-particle connections throughout the\nsystem. Because such systems are typically under-constrained, the observed\nforce network is not unique to a given particle configuration, but instead\nvaries upon repeated formation. In this paper, we examine the ensemble of force\nchain configurations created under repeated assembly in order to develop tools\nto statistically forecast the observed force network. In experiments on a\ngently suspended 2D layer of photoelastic particles, we subject the assembly to\nhundreds of repeated cyclic compressions. As expected, we observe the\nnon-unique nature of the force network, which differs for each compression\ncycle, by measuring all vector inter-particle contact forces using our open\nsource PeGS software. We find that total pressure on each particle in the\nsystem correlates to its betweenness centrality value extracted from the\ngeometric contact network. Thus, the mesoscale network structure is a key\ncontrol on individual particle pressures."
    },
    {
        "anchor": "Dynamics of dense Polyelectrolyte Solutions: We investigate a system of dense polyelectrolytes in solution. The Langevin\ndynamics of the system with linearized hydrodynamics is formulated in the\nfunctional integral formalism and a transformation made to collective\ncoordinates. Within a dynamical Random Phase Approximation (RPA) integration\nover the counter- and salt ions produces the Debye-H\\\"uckel-like screening of\nthe Coulomb interactions with dependence on the frequency only as part of a\nmore complicated coupling structure. We investigate the dynamics of the\nstructure factor as well as the collective diffusion coefficient and comment\nupon the viscosity of the whole system of polymers with counterions and fluid\nin the simplest approximation. The coupling of the various components of the\nsystem produces nontrivial diffusive behavior. We draw conclusions about the\nrelationship of the three length scales in the present system, i.e. the static\nscreening length, the hydrodynamic screening length and the Debye length.",
        "positive": "Two plateau moduli for actin gels: Conflicting experimental results have been reported for the plateau modulus\nin actin solutions: Analogies are often made with the viscoelastic behaviour of\nflexible polymers making use of the idea of entanglement as the source of the\nmacroscopic storage modulus. We resolve apparent experimental and theoretical\ncontradictions by pointing out the possibility of two distinct plateau regimes\nas a function of frequency in semidilute solutions of semiflexible polymers. We\nmake the point that longitudinal and transverse hindrance can have very\ndifferent effects at the macroscopic scale."
    },
    {
        "anchor": "Discontinuous Buckling of Wide Beams and Metabeams: We uncover how nonlinearities dramatically alter the buckling of elastic\nbeams. First, we show experimentally that sufficiently wide ordinary elastic\nbeams and specifically designed metabeams ---beams made from a mechanical\nmetamaterial--- exhibit discontinuous buckling, an unstable form of buckling\nwhere the post-buckling stiffness is negative. Then we use simulations to\nuncover the crucial role of nonlinearities, and show that beams made from\nincreasingly nonlinear materials exhibit increasingly negative post-buckling\nslope. Finally, we demonstrate that for sufficiently strong nonlinearity, we\ncan observe discontinuous buckling for metabeams as slender as $1\\%$\nnumerically and $5\\%$ experimentally.",
        "positive": "Rapid Spontaneous Assembly of Single Component Liposomes: We present a mechanism and show two variants of a method where the average\ndiameter of spontaneously (barrier-free) assembled single component unilamellar\nliposomes is intrinsic, in agreement with Helfrich's theory. It depends only on\nthe temperature and the lipid type, eliminating kinetic effects or external\nforcing normally observed. This provides the first pure system to study the\nself-assembly of vesicle forming components, and with a natural length scale it\nmay have an implication for vesicle size selection under pre-biotic conditions."
    },
    {
        "anchor": "Influence of van der Waals interactions on morphology and dynamics in\n  ultrathin liquid films at silicon oxide interfaces: Single molecule tracer diffusion studies of evaporating (thinning) ultrathin\ntetrakis-2-ethyl-hexoxysilane (TEHOS) films on silicon with 100 nm thermal\noxide reveal a considerable slowdown of the molecular mobility within less than\n4 nm above the substrate (corresponding to a few molecular TEHOS layers). This\nis related to restricted mobility and structure formation of the liquid in this\nregion, in agreement with information obtained from a long-time ellipsometric\nstudy of thinning TEHOS films on silicon substrates with 100 nm thermal or 2 nm\nnative oxide. Both show evidence for the formation of up to four layers.\nAdditionally, on thermal oxide, a lateral flow of the liquid is observed, while\nthe film on the native oxide forms an almost flat surface and shows negligible\nflow. Thus, on the 2 nm native oxide the liquid mobility is even more\nrestricted in close vicinity to the substrate as compared to the 100 nm thermal\noxide. In addition, we found a significantly smaller initial film thickness in\ncase of the native oxide under similar dipcoating conditions. We ascribe these\ndifferences to van der Waals interactions with the underlying silicon in case\nof the native oxide, whereas the thermal oxide suffices to shield those\ninteractions.",
        "positive": "A numerical technique for preserving the topology of polymer knots: The\n  case of short-range attractive interactions: The statistical mechanics of single polymer knots is studied using Monte\nCarlo simulations. The polymers are considered on a cubic lattice and their\nconformations are randomly changed with the help of pivot transformations.\nAfter each transformation, it is checked if the topology of the knot is\npreserved by means of a method called pivot algorithm and excluded area (in\nshort PAEA) and described in a previous publication of the authors. As an\napplication of this method the specific energy, the radius of gyration and heat\ncapacity of a few types of knots are computed. The case of attractive\nshort-range forces is investigated. The sampling of the energy states is\nperformed by means of the Wang-Landau algorithm. The obtained results show that\nthe specific energy and heat capacity increase with increasing knot complexity\nas in the case of repulsive interactions. The data about the gyration radius\nallow to estimate the size of the polymer knots at different temperatures."
    },
    {
        "anchor": "Vaporization and Layering of Alkanols at the Oil/Water Interface: This study of adsorption of normal alkanols at the oil/water interface with\nx-ray reflectivity and tensiometry demonstrates that the liquid to gas\nmonolayer phase transition at the hexane/water interface is thermodynamically\nfavorable only for long-chain alkanols. As the alkanol chain length is\ndecreased, the change in excess interfacial entropy per area decreases to zero.\nSystems with small values of excess interfacial entropy form multi-molecular\nlayers at the interface instead of the monolayer formed by systems with much\nlarger excess interfacial entropy. Substitution of n-hexane by n-hexadecane\nsignificantly alters the interfacial structure for a given alkanol surfactant,\nbut this substitution does not change fundamentally the phase transition\nbehavior of the monolayers. These data show that the critical alkanol carbon\nnumber, at which the change in excess interfacial entropy per area decreases to\nzero, is approximately six carbons larger than the number of carbons in the\nalkane solvent molecules.",
        "positive": "Phases and Transitions in Phantom Nematic Elastomer Membranes: Motivated by recently discovered unusual properties of bulk nematic\nelastomers, we study a phase diagram of liquid-crystalline polymerized phantom\nmembranes, focusing on in-plane nematic order. We predict that such membranes\nshould enerically exhibit five phases, distinguished by their conformational\nand in-plane orientational properties, namely isotropic-crumpled,\nnematic-crumpled, isotropic-flat, nematic-flat and nematic-tubule phases. In\nthe nematic-tubule phase, the membrane is extended along the direction of {\\em\nspontaneous} nematic order and is crumpled in the other. The associated\nspontaneous symmetries breaking guarantees that the nematic-tubule is\ncharacterized by a conformational-orientational soft (Goldstone) mode and the\nconcomitant vanishing of the in-plane shear modulus. We show that long-range\norientational order of the nematic-tubule is maintained even in the presence of\nharmonic thermal luctuations. However, it is likely that tubule's elastic\nproperties are ualitatively modified by these fluctuations, that can be studied\nusing a nonlinear elastic theory for the nematic tubule phase that we derive at\nthe end of this paper."
    },
    {
        "anchor": "Capillary fracture of ultrasoft gels: heterogeneity and delayed\n  nucleation: A droplet of surfactant spreading on an ultrasoft ($E \\lesssim 100$ Pa) gel\nsubstrate will produce capillary fractures at the gel surface; these fractures\noriginate at the contact-line and propagate outwards in a starburst pattern.\nThere is an inherent variability in both the number of fractures formed and the\ntime delay before fractures form. In the regime where single fractures form, we\nobserve a Weibull-like distribution of delay times, consistent with a\nthermally-activated process. The shape parameter is close to 1 for softer gels\n(a Poisson process), and larger for stiffer gels (indicative of aging). For\nsingle fractures, the characteristic delay time is primarily set by the\nelastocapillary length of the system, calculated from the differential in\nsurface tension between the droplet and the substrate, rather than the elastic\nmodulus as for stiffer systems. For multiple fractures, all fractures appear\nsimultaneously and long delay times are suppressed. The delay time distribution\nprovides a new technique for probing the energy landscape and fracture\ntoughness of ultrasoft materials.",
        "positive": "Mechanical properties of DNA and DNA nanostructures: comparison of\n  atomistic, martini and oxDNA: The flexibility and stiffness of small DNA play a fundamental role ranging\nfrom several biophysical processes to nano-technological applications. Here, we\nestimate the mechanical properties of short double-stranded DNA (dsDNA) having\nlength ranging from 12 base-pairs (bps) to 56 bps, paranemic crossover (PX)\nDNA, and hexagonal DNA nanotubes (DNTs) using two widely used coarse-grain\nmodels $-$ Martini and oxDNA. To calculate the persistence length ($L_p$) and\nthe stretch modulus ($\\gamma$) of the dsDNA, we incorporate the worm-like chain\nand elastic rod model, while for DNT, we implement our previously developed\ntheoretical framework. We compare and contrast all the results with previously\nreported all-atom molecular dynamics (MD) simulation and experimental results.\nThe mechanical properties of dsDNA ($L_p$ $\\sim$ 50nm, $\\gamma \\sim$ 800-1500\npN), PX DNA ($\\gamma \\sim$ 1600-2000 pN) and DNTs ($L_p \\sim 1-10\\ \\mu$m,\n$\\gamma \\sim$ 6000-8000 pN) estimated using Martini soft elastic network and\noxDNA are in very good agreement with the all-atom MD and experimental values,\nwhile the stiff elastic network Martini reproduces order of magnitude higher\nvalues of $L_p$ and $\\gamma$. The high flexibility of small dsDNA is also\ndepicted in our calculations. However, Martini models proved inadequate to\ncapture the salt concentration effects on the mechanical properties with\nincreasing salt molarity. OxDNA captures the salt concentration effect on small\ndsDNA mechanics. But it is found to be ineffective to reproduce the\nsalt-dependent mechanical properties of DNTs. Also, unlike Martini, the time\nevolved PX DNA and DNT structures from the oxDNA models are comparable to the\nall-atom MD simulated structures. Our findings provide a route to study the\nmechanical properties of DNA nanostructures with increased time and length\nscales and has a remarkable implication in the context of DNA nanotechnology."
    },
    {
        "anchor": "Modulational Instabilities and Domain Walls in Coupled Discrete\n  Nonlinear Schr\u00f6dinger Equations: We consider a system of two discrete nonlinear Schr\\\"{o}dinger equations,\ncoupled by nonlinear and linear terms. For various physically relevant cases,\nwe derive a modulational instability criterion for plane-wave solutions. We\nalso find and examine domain-wall solutions in the model with the linear\ncoupling.",
        "positive": "Crumples as a generic stress-focusing instability in confined sheets: Thin elastic solids are easily deformed into a myriad of three-dimensional\nshapes, which may contain sharp localized structures as in a crumpled candy\nwrapper, or have smooth and diffuse features like the undulating edge of a\nflower. Anticipating and controlling these morphologies is crucial to a variety\nof applications involving textiles, synthetic skins, and inflatable structures.\nHere we show that a \"wrinkle-to-crumple\" transition, previously observed in\nspecific settings, is a ubiquitous response for confined sheets. This unified\npicture is borne out of a suite of model experiments on polymer films confined\nto liquid interfaces with spherical, hyperbolic, and cylindrical geometries,\nwhich are complemented by experiments on macroscopic membranes inflated with\ngas. We use measurements across this wide range of geometries, boundary\nconditions, and lengthscales to quantify several robust morphological features\nof the crumpled phase, and we build an empirical phase diagram for crumple\nformation that disentangles the competing effects of curvature and compression.\nOur results suggest that crumples are a generic microstructure that emerge at\nlarge curvatures due to a competition of elastic and substrate energies."
    },
    {
        "anchor": "Registered and antiregistered phase separation of mixed amphiphilic\n  bilayers: We derive a mean-field free energy for the phase behaviour of coupled bilayer\nleaflets, which is implicated in cellular processes and important to the design\nof artificial membranes. Our model accounts for amphiphile-level structural\nfeatures, particularly hydrophobic mismatch, which promotes antiregistration\n(AR), in competition with the `direct' trans-midplane coupling usually studied,\npromoting registration (R). We show that the phase diagram of coupled leaflets\nallows multiple \\textit{metastable} coexistences, then illustrate the kinetic\nimplications with a detailed study of a bilayer of equimolar overall\ncomposition. For approximate parameters estimated to apply to phospholipids,\nequilibrium coexistence is typically registered, but metastable antiregistered\nphases can be kinetically favoured by hydrophobic mismatch. Thus a bilayer in\nthe spinodal region can require nucleation to equilibrate, in a novel\nmanifestation of Ostwald's `rule of stages'. Our results provide a framework\nfor understanding disparate existing observations, elucidating a subtle\ncompetition of couplings, and a key role for phase transition kinetics in\nbilayer phase behaviour.",
        "positive": "The trousers fracture test for viscoelastic elastomers: Shrimali and Lopez-Pamies (2023) have recently shown that the Griffith\ncriticality condition that governs crack growth in viscoelastic elastomers can\nbe reduced to a fundamental form that involves exclusively the intrinsic\nfracture energy $G_c$ of the elastomer and, in so doing, they have brought\nresolution to the complete description of the historically elusive notion of\ncritical tearing energy $T_c$. The purpose of this paper -- which can be viewed\nas the third installment of the series started by Shrimali and Lopez-Pamies\n(2023) -- is to make use of this fundamental form to explain one of the most\npopular fracture tests for probing the growth of cracks in viscoelastic\nelastomers, the trousers test."
    },
    {
        "anchor": "Kinetics of double stranded DNA overstretching revealed by 0.5-2 pN\n  force steps: A detailed description of the conformational plasticity of double stranded\nDNA (ds) is a necessary framework for understanding protein-DNA interactions.\nUntil now, however structure and kinetics of the transition from the basic\nconformation of ds-DNA (B state) to the 1.7 times longer and partially unwound\nconformation (S state) have not been defined. The force-extension relation of\nthe ds-DNA of lambda-phage is measured here with unprecedented resolution using\na dual laser optical tweezers that can impose millisecond force steps of 0.5-2\npN (25 C). This approach reveals the kinetics of the transition between\nintermediate states of ds-DNA and uncovers the load-dependence of the rate\nconstant of the unitary reaction step. DNA overstretching transition results\nessentially a two-state reaction composed of 5.85 nm steps, indicating\ncooperativity of ~25 base pairs. This mechanism increases the free energy for\nthe unitary reaction to ~94 kBT, accounting for the stability of the basic\nconformation of DNA, and explains the absence of hysteresis in the\nforce-extension relation at equilibrium. The novel description of the kinetics\nand energetics of the B-S transition of ds-DNA improves our understanding the\nbiological role of the S state in the interplay between mechanics and\nenzymology of the DNA-protein machinery.",
        "positive": "Accelerated rejuvenation in metallic glasses subjected to elastostatic\n  compression along alternating directions: The influence of static stress and alternating loading direction on the\npotential energy and mechanical properties of amorphous alloys is investigated\nusing molecular dynamics simulations. The model glass is represented via a\nbinary mixture which is first slowly annealed well below the glass transition\ntemperature and then subjected to elastostatic loading either along a single\ndirection or along two and three alternating directions. We find that at\nsufficiently large values of the static stress, the binary glass becomes\nrejuvenated via collective, irreversible rearrangements of atoms. Upon\nincluding additional orientation of the static stress in the loading protocol,\nthe rejuvenation effect is amplified and the typical size of clusters of atoms\nwith large nonaffine displacements increases. As a result of prolonged\nmechanical loading, the elastic modulus and the peak value of the stress\novershoot during startup continuous compression become significantly reduced,\nespecially for loading protocols with alternating stress orientation. These\nfindings are important for the design of novel processing methods to improve\nmechanical properties of metallic glasses."
    },
    {
        "anchor": "Bridging-induced microphase separation: photobleaching experiments,\n  chromatin domains, and the need for active reactions: We review the mechanism and consequences of the \"bridging-induced\nattraction\", a generic biophysical principle which underpins some existing\nmodels for chromosome organisation in 3-D. This attraction, which was revealed\nin polymer physics-inspired computer simulations, is a generic clustering\ntendency arising in multivalent chromatin-binding proteins, and it provides an\nexplanation for the biogenesis of nuclear bodies and transcription factories\nvia microphase separation. Including post-translational modification reactions\ninvolving these multivalent proteins can account for the fast dynamics of the\nensuing clusters, as is observed via microscopy and photobleaching experiments.\nThe clusters found in simulations also give rise to chromatin domains which\nconform well with the observation of A/B compartments in HiC experiments.",
        "positive": "Heat Transfer between Graphene and Amorphous SiO2: We study the heat transfer between graphene and amorphous SiO2. We include\nboth the heat transfer from the area of real contact, and between the surfaces\nin the non-contact region. We consider the radiative heat transfer associated\nwith the evanescent electromagnetic waves which exist outside of all bodies,\nand the heat transfer by the gas in the non-contact region. We find that the\ndominant contribution to the heat transfer result from the area of real\ncontact, and the calculated value of the heat transfer coefficient is in good\nagreement with the value deduced from experimental data."
    },
    {
        "anchor": "Rheology of dilute polymer solutions with time-dependent screening of\n  hydrodynamic interactions: The screening of hydrodynamic interactions (HI) essentially affects\nmacroscopic properties of polymeric solutions. This screening depends not only\non the polymer concentration but has a dynamic nature. In the present work, a\nbead-spring theory is developed, in which this phenomenon is described for\nsolutions of nonentangled polymer coils. The equation of motion for the beads\nof a test polymer is solved together with the Brinkman's equation for the\nsolvent velocity that takes into account the presence of other coils in\nsolution. The time correlation functions for the polymer normal modes are\nfound. A tendency to the screening of HI is demonstrated on the coil diffusion\nas well as on the relaxation of its internal modes. With the growing\nconcentration of the coils they both show a transition to the exact Rouse\nbehavior. The viscosity of the solution and some other observable quantities\nare calculated. As the time increaes, the time-dependent quantities change\ntheir behavior from the Rouse regime through the Zimm one again to the Rouse\ndynamics at long times.",
        "positive": "Novel Feature of Liquid Dynamics via Improvements in meV-Resolution\n  Inelastic X-Ray Scattering: We describe how improvements in methodology and instrumentation for\nmeV-resolved inelastic x-ray scattering (IXS), coupled with a fresh examination\nof older theory, allow identification of interaction between the quasi-elastic\nand acoustic dynamical modes in liquid water. This helps explain a decades old\ncontroversy about the appearance of additional modes in water spectra, and\nprovides a strong base from which to discuss new phenomena in liquids on the\nmesoscale."
    },
    {
        "anchor": "Multivalent \"Attacker & Guard\" Strategy for Targeting Surfaces with Low\n  Receptor Density: Multivalent particles, i.e. microscopic constructs having multiple ligands,\ncan be used to target surfaces selectively depending on their receptor density.\nTypically, there is a sharp onset of multivalent binding as the receptor\ndensity exceeds a given threshold. However, the opposite case, selectively\nbinding to surfaces with a receptor density below a given threshold, is much\nharder. Here, we present a simple strategy for selectively targeting a surface\nwith a low density of receptors, within a system also having a surface with a\nhigher density of the same receptors. Our strategy exploits competitive\nadsorption of two species. The first species, called \"guards\", are\nreceptor-sized monovalent particles designed to occupy the high-density surface\nat equilibrium, while the second multivalent \"attacker\" species outcompetes the\nguards for binding onto the low-density surface. Surprisingly, the recipe for\nattackers and guards yields more selective binding with stronger\nligand-receptor association constants, in contrast to standard multivalency. We\nderive explicit expressions for the attacker and guard molecular design\nparameters and concentrations, optimised within bounds of what is\nexperimentally accessible, thereby facilitating implementation of the proposed\napproach.",
        "positive": "Exploring the Pattern Formation of Lysozyme Drying Droplets in Phosphate\n  Buffer Saline Solution: The process of drying is a simple physical mechanism that drives a system to\nrelax from one equilibrium point to another. The native states of the\nconstituent particles in the droplets can be linked to the emergent\nmorphological patterns via this drying process. This paper explores the\ninterplay between different initial concentrations of a globular protein\nlysozyme ($\\phi_p$) and the salts ($\\phi_s$) in the phosphate buffer saline\n(PBS). The $\\phi_s$ = 0 wt% embodies the lysozyme solution prepared in\nde-ionized water. The samples at $\\phi_s$ = 0.9 wt% display a dark texture in\nthe central region. We examined the drying evolution and dried morphology by\nextracting the mean gray values (I) and standard deviation (SD). For this,\n$\\phi_p$ was fixed at 9.0 wt%, and only the $\\phi_s$ were varied. The I\ndecreases, and the SD increases as the salt crystals start appearing during the\ndrying process. The phase separation of these salts directly maps with this\ntextural evolution and is influenced by the salts' amount in these droplets.\nThe scanning electron microscopic images of the dried films at $\\phi_s$ = 0.5\nwt% at different $\\phi_p$ show that the lysozyme-salt interactions drop off in\nthe ring region. This ring becomes more apparent with the increasing $\\phi_p$.\nThough all the droplets show \"coffee-ring\" behavior, the leftover lysozyme\nparticles indicated with the mound-like structure diminishes in the salts'\npresence. The alteration of the crack patterns is also found. Therefore, the\nchemistry between multiple salts and lysozyme at various initial concentrations\nreveals that the features are not merely a sum (or average) of individual\nmicroscopic actions. It appears to involve both protein-protein and\nprotein-salt interactions partially averaged over one length/time scale that\nsets the next larger/longer length/time scale in such drying droplets."
    },
    {
        "anchor": "Nematic twist-bend phase of a bent liquid crystal dimer: field-induced\n  deformations of the helical structure, macroscopic polarization and fast\n  switching speeds: The twist-bend nematic (Ntb) phase is a recent addition to the nematic (N)\nphases of liquid crystals (LCs). A net polar order in the Ntb phase under an\nexternal electric field was predicted in several recent theoretical studies but\nyet to be experimentally realized. We investigated the polar nature, dielectric\nproperties, electro-optical switching and optical transmission properties of a\nbent LC dimer CB7CB. The LC showed a relatively high-temperature nematic (N)\nphase and a lower-temperature nematic (NX) phase (also called Ntb in\nliterature). A threshold-dependent polarization current response with large\npolarization values was obtained in the entire mesophase range. The associated\nswitching times were found in sub-millisecond region. This ferroelectric-like\npolarization resulted from collective reorientation of polar cybotactic\nclusters. In NX phase, electric field-induced deformation of twisted helical\nstructures also contributed to net polarization. Dielectric measurements\nconfirmed the presence of cybotactic clusters via relaxation processes with\nlarge activation energies. Deformation of the NX helical structure under\nexternal electric field was corroborated by polarized optical microscopy and\noptical transmission studies. The field-induced deformations, net polar order\nand fast switching will contribute towards greater understanding of the NX (or\nNtb) phase dynamics. It may also find applications in next-generation\nelectro-optic devices.",
        "positive": "Time-temperature superposition in viscous liquids: Dielectric relaxation measurements on supercooled triphenyl phosphite show\nthat at low temperatures time-temperature superposition (TTS) is accurately\nobeyed for the primary (alpha) relaxation process. Measurements on 6 other\nmolecular liquids close to the calorimetric glass transition indicate that TTS\nis linked to an $\\omega^{-1/2}$ high-frequency decay of the alpha loss, while\nthe loss peak width is nonuniversal."
    },
    {
        "anchor": "Fluid-Fluid and Fluid-Solid transitions in the Kern-Frenkel model from\n  Barker-Henderson thermodynamic perturbation theory: We study the Kern-Frenkel model for patchy colloids using Barker-Henderson\nsecond-order thermodynamic perturbation theory. The model describes a fluid\nwhere hard sphere particles are decorated with one patch, so that they interact\nvia a square-well (SW) potential if they are sufficiently close one another,\nand if patches on each particle are properly aligned. Both the gas-liquid and\nfluid-solid phase coexistences are computed and contrasted against\ncorresponding Monte-Carlo simulations results. We find that the perturbation\ntheory describes rather accurately numerical simulations all the way from a\nfully covered square-well potential down to the Janus limit (half coverage). In\nthe region where numerical data are not available (from Janus to hard-spheres),\nthe method provides estimates of the location of the critical lines that could\nserve as a guideline for further efficient numerical work at these low\ncoverages. A comparison with other techniques, such as integral equation\ntheory, highlights the important aspect of this methodology in the present\ncontext.",
        "positive": "Sugar-Pucker Force-Induced Transition in Single-Stranded~DNA: The accurate knowledge of the elastic properties of single-stranded DNA\n(ssDNA) is key to characterize the thermodynamics of molecular reactions that\nare studied by force spectroscopy methods where DNA is mechanically unfolded.\nExamples range from DNA hybridization, DNA ligand binding, DNA unwinding by\nhelicases, etc. To date, ssDNA elasticity has been studied with different\nmethods in molecules of varying sequence and contour length. A dispersion of\nresults has been reported and the value of the persistence length has been\nfound to be larger for shorter ssDNA molecules. We carried out pulling\nexperiments with optical tweezers to characterize the elastic response of ssDNA\nover three orders of magnitude in length (60-14 k bases). By fitting the\nforce-extension curves (FECs) to the Worm-Like Chain model we confirmed the\nabove trend:the persistence length nearly doubles for the shortest molecule (60\nb) with respect to the longest one (14 kb). We demonstrate that the observed\ntrend is due to the different force regimes fitted for long and short\nmolecules, which translates into two distinct elastic regimes at low and high\nforces. We interpret this behavior in terms of a force-induced sugar pucker\nconformational transition (C3'-endo to C2'-endo) upon pulling ssDNA."
    },
    {
        "anchor": "Reaching for the surface: Spheroidal microswimmers in surface gravity\n  waves: Microswimmers (planktonic microorganisms or artificial active particles)\nimmersed in a fluid interact with the ambient flow, altering their\ntrajectories. In surface gravity waves, a common goal for microswimmers is\nvertical migration (e.g., to reach the free surface or to dive to deeper\ndepths). By modelling microswimmers as spheroidal bodies with an intrinsic\nswimming velocity that supplements advection and reorientation by the flow, we\ninvestigate how shape and swimming affect vertical transport of microswimmers\nin waves. We find that it is possible for microswimmers to be initially\nswimming downwards, but to recover and head back to the surface, and vice\nversa. This is because the coupling between swimming and flow-induced\nreorientations introduces a shape dependency in the vertical transport. From a\nwave-averaged analysis of microswimmer trajectories, we show that each\ntrajectory is bounded by critical planes in the position-orientation phase\nspace that depend only on the shape. We also give explicit solutions to these\ntrajectories and determine the fraction of microswimmers that begin within the\nwater column and eventually reach the surface. For microswimmers that are\ninitially randomly oriented, the fraction that reach the surface increases\nmonotonically as the starting depth decreases, as expected, but also varies\nwith shape and swimming speed. In the limit of small swimming speed, the\nfraction of highly prolate microswimmers reaching the surface is 0.5,\nsuggesting that these swimmers would be able to choose direction of vertical\ntransport with small changes in swimming behaviour.",
        "positive": "Adsorption of symmetric random copolymer onto symmetric random surface:\n  the annealed case: Adsorption of a symmetric (AB) random copolymer (RC) onto a symmetric (ab)\nrandom heterogeneous surface (RS) is studied in the annealed approximation by\nusing a two-dimensional partially directed walk model of the polymer. We show\nthat in the symmetric case, the expected a posteriori compositions of the RC\nand the RS have correct values (corresponding to their a priori probabilities)\nand do not change with the temperature, whereas second moments of monomers and\nsites distributions in the RC and RS change. This indicates that monomers and\nsites do not interconvert but only rearrange in order to provide better\nmatching between them and, as a result, a stronger adsorption of the RC on the\nRS. However, any violation of the system symmetry shifts equilibrium towards\nthe major component and/or more favorable contacts and leads to interconversion\nof monomers and sites."
    },
    {
        "anchor": "Hourglass of constant weight: In contrast to a still common belief, a steadily flowing hourglass changes\nits weight in the course of time. We will show that, nevertheless, it is\npossible to construct hourglasses that do not change their weight.",
        "positive": "Rare events and disorder control the brittle yielding of well-annealed\n  amorphous solids: We use atomistic computer simulations to provide a microscopic description of\nthe brittle failure of amorphous materials, and we assess the role of rare\nevents and quenched disorder. We argue that brittle yielding originates at rare\nsoft regions, similarly to Griffiths effects in disordered systems. We\nnumerically demonstrate how localized plastic events in such soft regions\ntrigger macroscopic failure via the propagation of a shear band. This physical\npicture, which no longer holds in poorly annealed ductile materials, allows us\nto discuss the role of finite size effects in brittle yielding and reinforces\nthe similarities between yielding and other disorder-controlled nonequilibrium\nphase transitions."
    },
    {
        "anchor": "Properties of compatible solutes in aqueous solution: We have performed Molecular Dynamics simulations of ectoine, hydroxyectoine\nand urea in explicit solvent. Special attention has been spent on the local\nsurrounding structure of water molecules. Our results indicate that ectoine and\nhydroxyectoine are able to accumulate more water molecules than urea by a\npronounced ordering due to hydrogen bonds. We have validated that the charging\nof the molecules is of main importance resulting in a well defined hydration\nsphere. The influence of a varying salt concentration is also investigated.\nFinally we present experimental results of a DPPC monolayer phase transition\nthat validate our numerical findings.",
        "positive": "On the yielding of a defect-rich model crystal under shear: insights\n  from molecular dynamics simulations: Point defects in real crystals at finite temperatures are inevitable. Their\ndynamics severely influence the mechanical properties of crystals under shear\ngiving rise to nonlinear effects such as ductility. Therefore, it is crucial to\nexplore the interplay of the equilibrium point-defect diffusion timescales and\nshear-induced timescales to understand the plastic deformation of crystals.\nUsing extensive nonequilibrium molecular dynamics simulations, we present a\nstudy on the yielding behavior of cluster crystals (CC), an archetypal model\nfor defect-rich crystals where the crystalline structure is characterized by\nmultiple occupancies (cluster) of particles at a lattice site. In equilibrium,\nparticles diffuse via site-to-site hopping keeping the crystalline structure\nintact. We consider the CCs at a fixed density and different temperatures where\nit remains in the FCC structure, and the diffusion timescales of particles vary\ndepending on the temperature. We choose the range of shear rates, which covers\ntimescales higher and much lower than the equilibrium diffusion timescales at\nhigh temperatures. For the considered range of shear rates and temperatures,\nboth the macro and microscopic responses of CCs to the shear suggest that the\nyielding scenario remains independent of the diffusion of particles. It\ninvolves the plastic deformation of the underlying crystalline structure. The\naveraged local bond order parameters and local angle measurements demonstrate\nthe structural changes and cooperative movement of the center of masses of the\nclusters close to the yield point. A comparison with the soft-sphere (SS) FCC\ncrystal reveals the similarities in the yielding behavior of both systems.\nNonetheless, diffusion of particles influences certain features, such as a less\nprominent increase in the local bond order parameters and local angles close to\nthe yield point."
    },
    {
        "anchor": "Letter for the pressure effects on the electrostatic polarizability and\n  dispersive binding of off-center polarons in ionic and molecular systems: The question is raised about the pressure effects on the polarizability and\ndispersive binding in ionic and molecular systems. As an example we take the\neffect of hydrostatic pressure on the energy gap of phonon-coupled two-level\nsystems. Assuming a positive pressure coefficient for the gap, we predict a\ngradual transition from small vibronic polarons to large polarons as the\npressure is increased at constant coupling energy of a two-level system.\nConcomitantly, the universal dispersive binding degrades from strong at low\npressure to weak at high pressure as the system evolves from soft condensed\nmatter to hard condensed matter. Implications are discussed on the development\nof stellar substance at the early stages of the Universe.",
        "positive": "A Limit of Stability in Supercooled Liquid Clusters: We examine the metastable liquid phase of a supercooled gold nanocluster by\nstudying the free energy landscape using the largest solid-like embryo as an\norder parameter. Just below freezing, the free energy exhibits a local minimum\nat small embryo sizes and a maximum at larger embryo sizes which denotes the\ncritical embryo size. At T=660K the free energy becomes a monotonically\ndecreasing function of the order parameter as the liquid phase becomes\nunstable, indicating we have reached a spinodal. In contrast to the usual\nmean-field theory predictions, the size of the critical embryo remains finite\nas the spinodal is approached. We also calculate the rate of nucleation,\nindependently from our free energy calculations, and observe a rapid increase\nin its temperature dependence when the free energy barrier is in the order of\n$kT$. This supports the idea that freezing becomes a barrierless process around\nthe spinodal temperature."
    },
    {
        "anchor": "Participation in the Johari-Goldstein Process - Molecular Liquids versus\n  Polymers: We show using molecular dynamics simulations that simple diatomic molecules\nin the glassy state exhibit only limited participation in the Johari-Goldstein\n(JG) relaxation process. That is, with sufficient cooling local reorientations\nare essentially frozen for some molecules, while others continue to change\ntheir orientation significantly. Thus, the \"islands of mobility\" concept is\nvalid for these molecular glass-formers; only near the glass transition\ntemperature does every molecule undergo the JG process. In contrast, for a\nlinear polymer this dichotomy in the distribution of JG relaxation strengths is\nabsent - if any segments are changing their local orientation, all segments\nare.",
        "positive": "Topological Defects, Surface Geometry and Cohesive Energy of Twisted\n  Filament Bundles: Cohesive assemblies of filaments are a common structural motif found in\ndiverse contexts, ranging from biological materials such as fibrous proteins,\nto artificial materials such as carbon nanotube ropes and micropatterned\nfilament arrays. In this paper, we analyze the complex dependence of cohesive\nenergy on twist, a key structural parameter of both self-assembled and\nfabricated filament bundles. Based on the analysis of simulated ground states\nof cohesive bundles, we show that the non-linear influence of twist derives\nfrom two distinct geometric features of twisted bundles: (i) the geometrical\nfrustration of inter-filament packing in the bundle cross-section; and (ii) the\nevolution of the surface geometry of bundles with twist, which dictates the\ncohesive cost of non-contacting filaments at the surface. Packing frustration\nin the bundle core gives rise to the appearance of a universal sequence of\ntopological defects, excess 5-fold disclinations, with increasing twist, while\nthe evolution of filament contact at the surface of the bundle generically\nfavors twisted geometries for sufficiently long filaments. Our analysis of both\ncontinuum and discrete models of filament bundles shows that, even in the\nabsence of external torque or intrinsic chirality, cohesive energy universally\nfavors twisted ground states above a critical (length/radius) aspect ratio and\nbelow a critical filament stiffness threshold."
    },
    {
        "anchor": "Stability of thin fluid films characterised by a complex form of\n  structural/effective disjoining pressure: We discuss instabilities of fluid films of nanoscale thickness, with a\nparticular focus on films where the destabilising mechanism allows for linear\ninstability, metastability, and absolute stability. Our study is motivated by\nnematic liquid crystal films; however we note that similar instability\nmechanisms, and forms of the effective disjoining pressure, appear in other\ncontexts, such as the well-studied problem of polymeric films on two-layered\nsubstrates. The analysis is carried out within the framework of the long-wave\napproximation, which leads to a fourth order nonlinear partial different\nequation for the film thickness. Within the considered formulation, the nematic\ncharacter of the film leads to an additional contribution to the disjoining\npressure, changing its functional form. This effective disjoining pressure is\ncharacterised by the presence of a local maximum for non-vanishing film\nthickness. Such a form leads to complicated instability evolution that we study\nby analytical means, including application of marginal stability criteria, and\nby extensive numerical simulations that help us develop a better understanding\nof instability evolution in the nonlinear regime. This combination of\nanalytical and computational techniques allows us to reach novel understanding\nof relevant instability mechanisms, and of their influence on transient and\nfully developed fluid film morphologies.",
        "positive": "Critical behavior of a water monolayer under hydrophobic confinement: The properties of water can have a strong dependence on the confinement.\nHere, we consider a water monolayer nanoconfined between hydrophobic parallel\nwalls under conditions that prevent its crystallization. We investigate, by\nsimulations of a many-body coarse-grained water model, how the properties of\nthe liquid are affected by the confinement. We show, by studying the response\nfunctions and the correlation length and by performing finite-size scaling of\nthe appropriate order parameter, that at low temperature the monolayer\nundergoes a liquid-liquid phase transition ending in a critical point in the\nuniversality class of the two-dimensional (2D) Ising model. Surprisingly, by\nreducing the linear size L of the walls, keeping the walls separation h\nconstant, we find a 2D-3D crossover for the universality class of the\nliquid-liquid critical point for L/h~50, i.e. for a monolayer thickness that is\nsmall compared to its extension. This result is drastically different from what\nis reported for simple liquids, where the crossover occurs for L/h ~ 5, and is\nconsistent with experimental results and atomistic simulations. We shed light\non these findings showing that they are a consequence of the strong\ncooperativity and the low coordination number of the hydrogen bond network that\ncharacterizes water."
    },
    {
        "anchor": "Ultra-Slow Acoustic Energy Transport in Dense Fish Aggregates: A dramatic slowing down of acoustic wave transport in dense fish shoals is\nobserved in open-sea fish cages. By employing a multi-beam ultrasonic antenna,\nwe observe the coherent backscattering (CBS) phenomenon. We extract key\nparameters of wave transport such as the transport mean free path and the\nenergy transport velocity of diffusive waves from diffusion theory fits to the\nexperimental data. The energy transport velocity is found to be about 10 times\nsmaller than the speed of sound in water, a value that is exceptionally low\ncompared with most observations in acoustics. By studying different models of\nthe fish body, we explain the basic mechanism responsible for the observed very\nslow transport of ultrasonic waves in dense fish shoals. Our results show that,\nwhile the fish swim bladder plays an important role in wave scattering, other\norgans have to be considered to explain ultra-low energy transport velocities.",
        "positive": "Benchmark free energies and entropies for saturated and compressed water: We use molecular simulation to compute the thermodynamic properties of 7\nrigid models for water (SPC/E, TIP3P, TIP4P, TIP4P/2005, TIP4P/Ew, TIP5P, OPC)\nover a wide range of temperature and pressure. Carrying out Expanded\nWang-Landau simulations, we obtain a high accuracy estimate for the\ngrand-canonical partition function which, in turn, provides access to all\nproperties, including the free energy and entropy, both at the vapor-liquid\ncoexistence and for compressed water. The results at coexistence highlight the\nclose connection between the behavior of the statistical functions and the\nthermodynamic properties. They show that the subgroup\n(SPC/E,TIP4P/2005,TIP4P/Ew) provides the most accurate account of the\nvapor-liquid equilibrium properties. For compressed water, the comparison of\nthe simulation results to the experimental data establishes that the TIP4P/Ew\nmodel performs best among the 7 models considered here, and captures the\nexperimental trends for the dependence of entropy and molar Gibbs free energy\non pressure."
    },
    {
        "anchor": "Curvature-Driven Morphing of Non-Euclidean Shells: We investigate how thin structures change their shape in response to\nnon-mechanical stimuli that can be interpreted as variations in the structure's\nnatural curvature. Starting from the theory of non-Euclidean plates and shells,\nwe derive an effective model that reduces a three-dimensional stimulus to the\nnatural fundamental forms of the mid-surface of the structure, incorporating\nexpansion, or growth, in the thickness. Then, we apply the model to a variety\nof thin bodies, from flat plates to spherical shells, obtaining excellent\nagreement between theory and numerics. We show how cylinders and cones can\neither bend more or unroll, and eventually snap and rotate. We also study the\nnearly-isometric deformations of a spherical shell and describe how this shape\nchange is ruled by the geometry of a spindle. As the derived results stem from\na purely geometrical model, they are general and scalable.",
        "positive": "Phase separation and dynamical arrest for particles interacting with\n  mixed potentials--the case of globular proteins revisited: We examine the applicability of the extended law of corresponding states\n(ELCS) to equilibrium and non equilibrium features of the state diagram of the\nglobular protein lysozyme. We provide compelling evidence that the ELCS\ncorrectly reproduces the location of the binodal for different ionic strengths,\nbut fails in describing the location of the arrest line. We subsequently use\nMode Coupling Theory (MCT) to gain additional insight into the origin of these\nobservations. We demonstrate that while the critical point and the connected\nbinodal and spinodal are governed by the integral features of the interaction\npotential described by the normalized second virial coefficient, the arrest\nline is mainly determined by the attractive well depth or bond strength. This\narticle is published in Soft Matter. The reference is: DOI: 10.1039/c0sm01175d"
    },
    {
        "anchor": "Signature of multiple glassy states in micellar nanoparticle-polymer\n  composites: We present results of temperature dependent measurements of dynamics of\nmicellar nanoparticle - polymer composites of fixed volume fraction and\nvariable polymer chain grafting density. For nanoparticles with lower grafting\ndensity we observe dynamically arrested state at low temperatures corresponding\nto an attractive glass while at high temperature the same system shows\nrelaxation typical of a repulsive glass. For higher grafting density, the low\ntemperature dynamics resembles more of a gel which crosses over to a repulsive\nglass at high temperature. Possible reasons for such fascinating dynamical\ntransitions is delineated.",
        "positive": "Birefringent Graphene Oxide Liquid Crystals in Micro-channels for\n  Optical Switch: We propose a mechanical-hydrodynamical experimental setup in which the\nmicrofluidic motion manipulates the optical birefringence of levitated graphene\noxide liquid crystal. The birefringence of the sample is changed by flowing\ngraphene oxide liquid crystal in the micro-channel. By measuring the ordinary\nand extraordinary refractive indices at five flow rates, one can determine the\nvalue of the birefringence of the samples, precisely. Our results demonstrate\nthat, by adjusting the concentration and flow rate of dispersion of the\ngraphene oxide nano flakes, the induced birefringence can be controlled. It is\nalso shown that this approach can be used as an optical switch."
    },
    {
        "anchor": "What Caging Force Cells Feel in 3D Hydrogels: A Rheological Perspective: It is established that the mechanical properties of hydrogels control the\nfate of (stem) cells. However, despite its importance, a one-to-one\ncorrespondence between gels' stiffness and cell behaviour is still missing from\nliterature. In this work, the viscoelastic properties of Poly(ethylene-glycol)\n(PEG)-based hydrogels - broadly used in 3D cell cultures and whose mechanical\nproperties can be tuned to resemble those of different biological tissues - are\ninvestigated by means of rheological measurements performed at different length\nscales. When compared with literature values, the outcomes of this work reveal\nthat conventional bulk rheology measurements may overestimate the stiffness of\nhydrogels by up to an order of magnitude. It is demonstrated that this apparent\nstiffening is caused by an induced 'tensional state' of the gel network, due to\nthe application of a compressional normal force during measurements. Moreover,\nit is shown that the actual stiffness of the hydrogels is instead accurately\ndetermined by means of passive-video-particle-tracking (PVPT) microrheology\nmeasurements, which are inherently performed at cells length scales and in\nabsence of any externally applied force. These results underpin a methodology\nfor measuring the linear viscoelastic properties of hydrogels that are\nrepresentative of the mechanical constraints felt by cells in 3D hydrogel\ncultures.",
        "positive": "Investigating molecular mechanism for the stability of ternary systems\n  containing cetrimide, fatty alcohol and water by using computer simulation: Computer simulations using atomistic model are carried out to investigate the\nstability of ternary systems of pure or mixed fatty alcohols, cetrimide, and\nwater. These semi$-$solid oil-in-water systems are used as the main component\nof pharmaceutical creams. Experiments show that the mixed alcohol systems are\nmore stable than pure ones. The current experimental hypothesis is that this is\nthe result of the length mismatch of the alkyl chains. This leads to higher\nconfigurational entropy of the chain tip of the longer alcohol molecules. Our\nsimulation results support this hypothesis. The results also show that the\nshorter alcohol molecules become stiffer with higher values of the deuterium\norder parameters and smaller area per molecule. The magnitude in fluctuations\nin the area per molecule also increases in mixed systems, indicating a higher\nconfigurational entropy. Analysis of the molecular structure of simulated\nsystems also shows good agreements with experimental data."
    },
    {
        "anchor": "Untangling superposed double layer and structural forces across confined\n  nanoparticle suspensions: The description of forces across confined complex fluids still holds many\nchallenges due to the possible overlap of different contributions. Here, an\nattempt is made to untangle the interaction between charged surfaces across\nnanoparticle suspensions. Interaction forces are measured using colloidal-probe\natomic force microscopy. The experimental force profiles are considered as a\nsuperposition of double layer and structural forces. In order to independently\ndescribe the decay of the double layer force, the ionic strength of the\nsuspension is determined by electrolytic conductivity measurements. Jellium\napproximation is used to define the impact of the fluid on screening the\nsurface potential. There, the nanoparticles are considered homogeneously\ndistributed across the fluid and screening is only carried out via the\nparticles counterions and added salt. The structural force follows a damped\noscillatory profile due to the layer-wise expulsion of the nanoparticles upon\napproach of both surfaces. The description of the oscillatory structural force\nis extended by a depletion layer next to the confining surfaces, with no\nnanoparticles present. The thickness of the depletion layer is related to the\nelectrostatic repulsion of the charged nanoparticles from the like-charged\nsurfaces. The results show that the total force profile is a superposition of\nindependent force contributions without any mutual effects. Using this rather\nsimple model describes the complete experimentally determined interaction force\nprofiles very well from surface separations of a few hundred nanometres down to\nthe surfaces being almost in contact.",
        "positive": "How to deform an egg yolk? On the Study of Soft Matter Deformation in a\n  Liquid Environment: In this paper, we report a novel experimental and theoretical study to\nexamine the response of a soft capsule bathed in a liquid environment to sudden\nexternal impacts. Taking an egg yolk as an example, we found that the soft\nmatter is not sensitive to translational impacts, but is very sensitive to\nrotational, especially decelerating-rotational impacts, during which the\ncentrifugal force and the shape of the membrane together play a critical role\ncausing the deformation of the soft object. This finding, as the first study of\nits kind, reveals the fundamental physics behind the motion and deformation of\na membrane-bound soft object, e.g., egg yolk, cells, soft brain matter, etc.,\nin response to external impacts."
    },
    {
        "anchor": "Why the smectic A -- hexatic phase transition does not follow its\n  universality class?: We resolve the old riddle related to the critical behavior of the heat\ncapacity near the smectic A -- hexatic second order phase transition.\nExperiment suggests a \"large\" positive specific heat critical exponent\ninconsistent with the universality class for this phase transition implying the\nvery small negative exponent. We show that essential features of the heat\ncapacity for the smectic A -- hexatic phase transition can be rationalized in\nthe framework of a theoretical model treating jointly fluctuations of the\nhexatic orientational order and of the positional (translational) order\nparameters. Assuming that the positional (translational) correlation length is\nlarger than the hexatic correlation length, we calculate a temperature\ndependence of the specific heat in the critical region near the smectic A --\nhexatic phase transition. Our results are in a quantitative agreement with the\ncalorimetric experimental data.",
        "positive": "Diffusion-influenced reaction rates in the presence of pair interactions: The kinetics of bimolecular reactions in solution depends, among other\nfactors, on intermolecular forces such as steric repulsion or electrostatic\ninteraction. Microscopically, a pair of molecules first has to meet by\ndiffusion before the reaction can take place. In this work, we establish an\nextension of Doi's volume reaction model to molecules interacting via pair\npotentials, which is a key ingredient for interacting-particle-based\nreaction-diffusion (iPRD) simulations. As a central result, we relate model\nparameters and macroscopic reaction rate constants in this situation. We solve\nthe corresponding reaction-diffusion equation in the steady state and derive\nsemi-analytical expressions for the reaction rate constant and the local\nconcentration profiles. Our results apply to the full spectrum from well-mixed\nto diffusion--limited kinetics. For limiting cases, we give explicit formulas,\nand we provide a computationally inexpensive numerical scheme for the general\ncase, including the intermediate, diffusion-influenced regime. The obtained\nrate constants decompose uniquely into encounter and formation rates, and we\ndiscuss the effect of the potential on both subprocesses, exemplified for a\nsoft harmonic repulsion and a Lennard-Jones potential. The analysis is\ncomplemented by extensive stochastic iPRD simulations, and we find excellent\nagreement with the theoretical predictions."
    },
    {
        "anchor": "Stability of Colloidal Quasicrystals: Freezing of charge-stabilized colloidal suspensions and relative stabilities\nof crystals and quasicrystals are studied using thermodynamic perturbation\ntheory. Macroion interactions are modelled by effective pair potentials\ncombining electrostatic repulsion with polymer-depletion or van der Waals\nattraction. Comparing free energies -- counterion terms included -- for\nelementary crystals and rational approximants to icosahedral quasicrystals,\nparameters are identified for which one-component quasicrystals are stabilized\nby a compromise between packing entropy and cohesive energy.",
        "positive": "Bond-orientational ordering and shear rigidity in modulated colloidal\n  liquids: From Landau-Alexander-McTague theory and Monte-Carlo simulation results we\nshow that the modulated liquid obtained by subjecting a colloidal system to a\nperiodic laser modulation has long range bond-orientational order and non-zero\nshear rigidity. From infinite field simulation results we show that in the\nmodulated liquid phase, the translational order parameter correlation function\ndecays to zero exponentially while the correlation function for the\nbond-orientational order saturates to a finite value at large distances."
    },
    {
        "anchor": "Magnetostriction in magnetic gels and elastomers as a function of the\n  internal structure and particle distribution: Magnetic gels and elastomers are promising candidates to construct reversibly\nexcitable soft actuators, triggered from outside by magnetic fields. These\nmagnetic fields induce or alter the magnetic interactions between discrete\nrigid particles embedded in a soft elastic polymeric matrix, leading to overall\ndeformations. It is a major challenge in theory to correctly predict from the\ndiscrete particle configuration the type of deformation resulting for a\nfinite-sized system. Considering an elastic sphere, we here present such an\napproach. The method is in principle exact, at least within the framework of\nlinear elasticity theory and for large enough interparticle distances.\nDifferent particle arrangements are considered. We find, for instance, that\nregular simple cubic configurations show elongation of the sphere along the\nmagnetization if oriented along a face or space diagonal of the cubic unit\ncell. Contrariwise, with the magnetization along the edge of the cubic unit\ncell, they contract. The opposite is true in this geometry for body- and\nface-centered configurations. Remarkably, for the latter configurations but the\nmagnetization along a face or space diagonal of the unit cell, contraction was\nobserved to revert to expansion with decreasing Poisson ratio of the elastic\nmaterial. Randomized configurations were considered as well. They show a\ntendency of elongating the sphere along the magnetization, which is more\npronounced for compressible systems. Our results can be tested against actual\nexperiments for spherical samples. Moreover, our approach shall support the\nsearch of optimal particle distributions for a maximized effect of actuation.",
        "positive": "Rheology of dense suspensions under shear rotation: Dense non-Brownian suspensions exhibit a spectacular and abrupt drop in\nviscosity under change of shear direction, as revealed by shear inversions\n(reversals) or orthogonal superposition. Here, we introduce an experimental\nsetup to systematically explore their response to shear rotations, where one\nsuddenly rotates the principal axes of shear by an angle $\\theta$, and measure\nthe shear stresses with a bi-axial force sensor. Our measurements confirm the\ngenericness of the transient decrease of the resistance to shear under unsteady\nconditions. Moreover, the orthogonal shear stress, which vanishes in steady\nstate, takes non-negligible values with a rich $\\theta$-dependence, changing\nqualitatively with solid volume fraction $\\phi$, and resulting in a force that\ntends to reduce or enhance the direction of flow for small or large $\\phi$.\nThese experimental findings are confirmed and rationalized by particle-based\nnumerical simulations and a recently proposed constitutive model. We show that\nthe rotation angle dependence of the orthogonal stress results from a\n$\\phi$-dependent interplay between hydrodynamic and contact stresses."
    },
    {
        "anchor": "Testing quantum correlations in a confined atomic cloud by scattering\n  fast atoms: We suggest measuring one-particle density matrix of a trapped ultracold\natomic cloud by scattering fast atoms in a pure momentum state off the cloud.\nThe lowest-order probability of the inelastic process, resulting in a pair of\noutcoming fast atoms for each incoming one, turns out to be given by a Fourier\ntransform of the density matrix. Accordingly, important information about\nquantum correlations can be deduced directly from the differential scattering\ncross-section. A possible design of the atomic detector is also discussed.",
        "positive": "Collective dynamics effect transient subdiffusion of inert tracers in\n  gel networks: Based on extensive Brownian dynamics simulations we study the thermally\ndriven motion of a tracer bead in a cross-linked, dynamic gel network in the\nlimit when the tracer bead's size is of the same size or even larger than the\nequilibrium mesh size of the gel. The analysis of long individual trajectories\nof the tracer bead demonstrates the existence of pronounced transient anomalous\ndiffusion, accompanied by a drastic slow-down of the gel-bead relaxation\ndynamics. From the time averaged mean squared displacement and the van Hove\ncross-correlation function we elucidate the many-body origin of the\nnon-Brownian tracer bead dynamics. Our results shed new light on the ongoing\ndebate over the physical origin of sterical tracer interactions with structured\nenvironments."
    },
    {
        "anchor": "Dissociation rates from single-molecule pulling experiments under large\n  thermal fluctuations or large applied force: Theories that are used to extract energy-landscape information from\nsingle-molecule pulling experiments in biophysics are all invariably based on\nKramers' theory of thermally-activated escape rate from a potential well. As is\nwell known, this theory recovers the Arrhenius dependence of the rate on the\nbarrier energy, and crucially relies on the assumption that the barrier energy\nis much larger than $k_{B}T$ (limit of comparatively low thermal fluctuations).\nAs was already shown in Dudko, Hummer, Szabo Phys. Rev. Lett. (2006), this\napproach leads to the unphysical prediction of dissociation time increasing\nwith decreasing binding energy when the latter is lowered to values comparable\nto $k_{B}T$ (limit of large thermal fluctuations). We propose a new theoretical\nframework (fully supported by numerical simulations) which amends Kramers'\ntheory in this limit, and use it to extract the dissociation rate from\nsingle-molecule experiments where now predictions are physically meaningful and\nin agreement with simulations over the whole range of applied forces (binding\nenergies). These results are expected to be relevant for a large number of\nexperimental settings in single-molecule biophysics.",
        "positive": "Molecular dynamics simulation study of the high frequency sound waves in\n  the fragile glass former ortho-terphenyl: Using a realistic flexible molecule model of the fragile glass former\northoterphenyl, we calculate via molecular dynamics simulation the collective\ndynamic structure factor, recently measured in this system by Inelastic X-ray\nScattering. The comparison of the simulated and measured dynamic structure\nfactor, and the study of its properties in an extended momentum, frequency and\ntemperature range allows: i) to conclude that the utilized molecular model\ngives rise to a dynamic structure factor in agreement with the experimental\ndata, for those thermodynamic states and momentum values where the latter are\navailable; ii) to confirm the existence of a slope discontinuity on the\nT-dependence of the sound velocity that, at finite Q, takes place at a\ntemperature T_x higher than the calorimetric glass transition temperature T_g;\niii) to find that the values of T_x is Q-dependent and that its vanishing Q\nlimit is consistent with T_g. The latter finding is interpreted within the\nframework of the current description of the dynamics of supercooled liquids in\nterms of exploration of the potential energy landscape."
    },
    {
        "anchor": "Clustering in vibrated monolayers of granular rods: We investigate the ordering properties of vertically-vibrated monolayers of\ngranular cylinders in a circular container at high packing fraction. In line\nwith previous works by other groups, we identify liquid-crystalline ordering\nbehaviour similar to that of two-dimensional hard rectangular particles subject\nto thermal equilibrium fluctuations. However, due to dissipation, there is a\nmuch stronger tendency for particles to cluster into parallel arrangements in\nthe granular system. These clusters behave as a polydisperse mixture of long\nlife-time `superparticles', and some aspects of the system behaviour can be\nunderstood by applying mean-field theories for equilibrium hard rectangles,\nbased on two-body correlations, to these `superparticles'. Many other features\nof the granular system are different: (i) For small particle length-to-breadth\nratio $\\kappa$, we identify tetratic ordering at moderate packing fractions and\nsmectic fluctuations at higher packing fractions, with no sharp transition\nbetween the two states. Both types of ordering can be explained in terms of\nclustering. (ii) For large $\\kappa$, strong clustering precludes the\nstabilisation of a uniaxial nematic state, and the system exhibits a mixture of\nrandomly-oriented clusters which, as packing fraction is increased, develops\ninto states with smectic fluctuations, again through a diffuse transition.\n(iii) Vorticity excitations of the velocity field compete with smectic\nordering, causing dynamic fluctuations and the absence of steady states at high\ndensities; the tetratic state, by contrast, is very stiff against vorticity,\nand long-standing steady states, spatially and orientationally homogeneous\nexcept for four symmetrical defects located close to the wall, can be observed.",
        "positive": "Growing smooth interfaces with inhomogeneous, moving external fields:\n  dynamical transitions, devil's staircases and self-assembled ripples: We study the steady state structure and dynamics of an interface in a pure\nIsing system on a square lattice placed in an inhomogeneous external field. The\nfield has a profile with a fixed shape designed to stabilize a flat interface,\nand is translated with velocity v_e. For small v_e, the interface is stuck to\nthe profile, is macroscopically smooth, and is rippled with a periodicity in\ngeneral incommensurate with the lattice parameter. For arbitrary orientations\nof the profile, the local slope of the interface locks in to one of infinitely\nmany rational values (devil's staircase) which most closely approximates the\nprofile. These ``lock-in'' structures and ripples dissappear as v_e increases.\nFor still larger v_e the profile detaches from the interface which is now\ncharacterized by standard Kardar-Parisi-Zhang (KPZ) exponents."
    },
    {
        "anchor": "Phantom chain simulations for fracture of polymer networks created from\n  star polymer mixtures of different functionalities: Fujiyabu et al. have experimentally reported that mixing of 3-arm star\nprepolymers into 4-arm analog improves the toughness of the resultant polymer\nnetworks compared to the base network composed of 4-arm star polymers only. For\nthe mechanism of this phenomenon, this study conducted phantom chain\nsimulations for polymer networks composed of mixtures of star branch\nprepolymers with equal arm length and different arm numbers, (f_1,f_2 )=(3,4),\n(3,6) and (3,8), for various f_1=3 prepolymer fractions {\\phi}_3. The networks\nwere created via end-linking reactions between prepolymers traced by a Brownian\ndynamics scheme, and the network structure was stored at different conversion\nratios {\\phi}_c, ranging from 0.6 and 0.9. The cycle rank of the gelated\nnetworks {\\xi} is fully consistent with the mean field theory, demonstrating\nthat the examined network structure is statistically fair. The networks were\nstretched with energy minimization until the break, and fracture\ncharacteristics including strain at break {\\epsilon}_b, stress at break\n{\\sigma}_b, work for fracture W_b, and the ratio of broken strands {\\phi}_bb,\nwere obtained. {\\epsilon}_b, {\\sigma}_b/{\\phi}_bb, and W_b/{\\phi}_bb data\nplotted against {\\xi} roughly follow the master curves reported for the base\nnetworks without mixing, implying that the change of fracture properties by the\nmixing of f_1=3 mainly corresponds to a decrease of {\\xi}. The mixing slightly\nsuppresses {\\sigma}_b/{\\phi}_bb and W_b/{\\phi}_bb for large f_2 cases compared\nto the base networks because of a biased breakage at the network strands\nwithout extenders, which are prepolymers with only two reacted arms. The\nanalysis for broken strands exhibited a new master curve for the\n{\\xi}-dependence of the molecular weight of broken strands.",
        "positive": "Elasticity of Stiff Biopolymers: We present a statistical mechanical study of stiff polymers, motivated by\nexperiments on actin filaments and the considerable current interest in polymer\nnetworks. We obtain simple, approximate analytical forms for the\nforce-extension relations and compare these with numerical treatments. We note\nthe important role of boundary conditions in determining force-extension\nrelations. The theoretical predictions presented here can be tested against\nsingle molecule experiments on neurofilaments and cytoskeletal filaments like\nactin and microtubules. Our work is motivated by the buckling of the\ncytoskeleton of a cell under compression, a phenomenon of interest to biology."
    },
    {
        "anchor": "Optimal navigation strategy of active Brownian particles in\n  target-search problems: We investigate exploration patterns of a microswimmer, modeled as an active\nBrownian particle, searching for a target region located in a well of an energy\nlandscape and separated from the initial position of the particle by high\nbarriers. We find that the microswimmer can enhance its success rate in finding\nthe target by tuning its activity and its persistence in response to features\nof the environment. The target-search patterns of active Brownian particles are\ncounterintuitive and display characteristics robust to changes of the energy\nlandscape. On the contrary, the transition rates and transition-path times are\nsensitive to the details of the specific energy landscape. In striking contrast\nto the passive case, the presence of additional local minima does not\nsignificantly slow down the active target-search dynamics.",
        "positive": "The Stability Balloon for Two-dimensional Vortex Ripple Patterns: Patterns of vortex ripples form when a sand bed is subjected to an\noscillatory fluid flow. Here we describe experiments on the response of regular\nvortex ripple patterns to sudden changes of the driving amplitude a or\nfrequency f. A sufficient decrease of f leads to a \"freezing\" of the pattern,\nwhile a sufficient increase of f leads to a supercritical secondary \"pearling\"\ninstability. Sufficient changes in the amplitude a lead to subcritical\nsecondary \"doubling\" and \"bulging\" instabilities. Our findings are summarized\nin a \"stability balloon\" for vortex ripple pattern formation."
    },
    {
        "anchor": "Polyelectrolyte Multilayering on a Charged Sphere: The adsorption of highly \\textit{oppositely} charged flexible\npolyelectrolytes onto a charged spherical surface is investigated by means of\nMonte Carlo simulations in a fashion which resembles the layer-by-layer\ndeposition technique introduced by Decher. Electroneutrality is insured at each\nstep by the presence of monovalent counterions (anions and cations). We study\nin detail the structure of the \\textit{equilibrium} complex. Our investigations\nof the first few layer formations strongly suggest that multilayering in\nspherical geometry is not possible as an equilibrium process with purely\nelectrostatic interactions. We especially focus on the influence of specific\n(non-electrostatic) short range attractive interactions (e.g., Van der Waals)\non the stability of the multilayers.",
        "positive": "Pancake bouncing on superhydrophobic surfaces: Engineering surfaces that promote rapid drop detachment is of importance to a\nwide range of applications including anti-icing, dropwise condensation6, and\nself-cleaning. Here we show how superhydrophobic surfaces patterned with\nlattices of submillimetre-scale posts decorated with nano-textures can generate\na counter-intuitive bouncing regime: drops spread on impact and then leave the\nsurface in a flattened, pancake shape without retracting. This allows for a\nfour-fold reduction in contact time compared to conventional complete rebound.\nWe demonstrate that the pancake bouncing results from the rectification of\ncapillary energy stored in the penetrated liquid into upward motion adequate to\nlift the drop. Moreover, the timescales for lateral drop spreading over the\nsurface and for vertical motion must be comparable. In particular, by designing\nsurfaces with tapered micro/nanotextures which behave as harmonic springs, the\ntimescales become independent of the impact velocity, allowing the occurrence\nof pancake bouncing and rapid drop detachment over a wide range of impact\nvelocities."
    },
    {
        "anchor": "Evidence of robust, universal conformal invariance in living biological\n  matter: Collective cellular movement plays a crucial role in many processes\nfundamental to health, including development, reproduction, infection, wound\nhealing, and cancer. The emergent dynamics that arise in these systems are\ntypically thought to depend on how cells interact with one another and the\nmechanisms used to drive motility, both of which exhibit remarkable diversity\nacross different biological systems. Here, we report experimental evidence of a\nuniversal feature in the patterns of flow that spontaneously emerges in groups\nof collectively moving cells. Specifically, we demonstrate that the flows\ngenerated by collectively moving dog kidney cells, human breast cancer cells,\nand by two different strains of pathogenic bacteria, all exhibit conformal\ninvariance. Remarkably, not only do our results show that all of these very\ndifferent systems display robust conformal invariance, but we also discovered\nthat the precise form of the invariance in all four systems is described by the\nSchramm-Loewner Evolution (SLE), and belongs to the percolation universality\nclass. A continuum model of active matter can recapitulate both the observed\nconformal invariance and SLE form found in experiments. The presence of\nuniversal conformal invariance reveals that the macroscopic features of living\nbiological matter exhibit universal translational, rotational, and scale\nsymmetries that are independent of the microscopic properties of its\nconstituents. Our results show that the patterns of flows generated by diverse\ncellular systems are highly conserved and that biological systems can\nunexpectedly be used to experimentally test predictions from the theories for\nconformally invariant structures",
        "positive": "Chiral edge currents in confined fibrosarcoma cells: During metastatic dissemination, streams of cells collectively migrate\nthrough a network of narrow channels within the extracellular matrix, before\nentering into the blood stream. This strategy is believed to outperform other\nmigration modes, based on the observation that individual cancer cells can take\nadvantage of confinement to switch to an adhesion-independent form of\nlocomotion. Yet, the physical origin of this behaviour has remained elusive and\nthe mechanisms behind the emergence of coherent flows in populations of\ninvading cells under confinement are presently unknown. Here we demonstrate\nthat human fibrosarcoma cells (HT1080) confined in narrow stripe-shaped regions\nundergo collective migration by virtue of a novel type of topological edge\ncurrents, resulting from the interplay between liquid crystalline (nematic)\norder, microscopic chirality and topological defects. Thanks to a combination\nof in vitro experiments and theory of active hydrodynamics, we show that, while\nheterogeneous and chaotic in the bulk of the channel, the spontaneous flow\narising in confined populations of HT1080 cells is rectified along the edges,\nleading to long-ranged collective cell migration, with broken chiral symmetry.\nThese edge currents are fuelled by layers of +1/2 topological defects,\northogonally anchored at the channel walls and acting as local sources of\nchiral active stress. Our work highlights the profound correlation between\nconfinement and collective migration in multicellular systems and suggests a\npossible mechanism for the emergence of directed motion in metastatic cancer."
    },
    {
        "anchor": "A generalized Young's equation to bridge a gap between the\n  experimentally measured and the theoretically calculated line tensions: A generalized Young's equation, which takes into account two corrections to\nthe line tension by the curvature dependence of the liquid-vapor surface\ntension and by the contact angle dependence of the intrinsic line tension, is\nderived from the thermodynamic free-energy minimization. The correction from\nthe curvature dependence can be qualitatively estimated using Tolman's formula.\nThe correction from the contact angle dependence can be estimated for\nnanometer-scale droplets for which the analytical formula for the intrinsic\nline tension determined from the van der Waals interaction is available. The\ntwo corrections to the apparent line tension of this van der Waals\nnano-droplets are as small as nN, and lead to either a positive or a negative\napparent line tension. The gravitational line tension for millimeter-scale\ndroplets by the gravitational acceleration is also considered. The\ngravitational line tension is of the order of $\\mu$N so that the correction\nfrom the curvature dependence can be neglected. Yet, the contact angle\ndependence is so large that the apparent line tension becomes always negative\nthough the intrinsic line tension without the correction is always positive.\nThese two examples demonstrate clear distinction between the theoretical\ncalculated intrinsic line tension and the experimentally determined apparent\nline tension which includes these two corrections. Naive comparison of the\nexperimentally determined and the theoretically calculated line tension is not\nalways possible.",
        "positive": "Compressed Exponential Relaxation as Superposition of Dual Structure in\n  Pattern Dynamics of Nematic Liquid Crystals: Soft-mode turbulence (SMT) is the spatiotemporal chaos observed in\nhomeotropically aligned nematic liquid crystals, where non-thermal fluctuations\nare induced by nonlinear coupling between the Nambu-Goldstone and convective\nmodes. The net and modal relaxations of the disorder pattern dynamics in SMT\nhave been studied to construct the statistical physics of nonlinear\nnonequilibrium systems. The net relaxation dynamics is well-described by a\ncompressed exponential function and the modal one satisfies a dual structure,\ndynamic crossover accompanied by a breaking of time-reversal invariance.\nBecause the net relaxation is described by a weighted mean of the modal ones\nwith respect to the wave number, the compressed-exponential behavior emerges as\na superposition of the dual structure. Here, we present experimental results of\nthe power spectra to discuss the compressed-exponential behavior and the dual\nstructure from a viewpoint of the harmonic analysis. We also derive a\nrelationship of the power spectra from the evolution equation of the modal\nautocorrelation function. The formula will be helpful to study non-thermal\nfluctuations in experiments such as the scattering methods."
    },
    {
        "anchor": "A note on a weakly singular elliptic equation from theory of elasticity: Qualitative properties of a second order elliptic equation from the\nanisotropic elasticity are investigated. Some explicit solutions for a disk are\npresented. Behaviour of these solutions in dependence of coefficients is\ninvestigated. The problem of presence of singularities of solutions at the\norigin of coordinates is discussed.",
        "positive": "Polymer Physics: Phenomenology of Polymeric Fluid Simulations --\n  Chapter: Collective Coordinates and Collective Models: Polymer Physics: Phenomenology of Polymeric Fluid Simulations is a review\nvolume that I am writing. I anticipate it will take a while to complete, so I\nam supplying individual chapters when each is more-or-less completed.\n  This Chapter considers collective coordinates and collective models for\nisolated polymer chains. Collective coordinates can be effective tools for\nisolating aspects of polymer motion that are less obvious if only the Cartesian\ncoordinates of the individual atoms or monomers are viewed. I treat Fourier,\nRouse, and Haar wavelets as suppliers of collective coordinates. One of the\nsets of collective coordinates that i consider, the Rouse coordinates, follows\nnaturally from the Rouse model of polymer dynamics. We therefore consider the\nRouse model as well as its more important predecessor, the Kirkwood-Riseman\nmodel. Haar wavelets are noteworthy because they allow one to isolate\nindividual regions of a polymer"
    },
    {
        "anchor": "Memory in aged granular media: Stimulated by recent experimental results, we simulate\n``temperature''-cycling experiments in a model for the compaction of granular\nmedia. We report on the existence of two types of memory effects: short-term\ndependence on the history of the sample, and long-term memory for highly\ncompact (aged) systems. A natural interpretation of these results is provided\nby the analysis of the density heterogeneities.",
        "positive": "Micro-mechanical Failure Analysis of Wet Granular Matter: We employ a novel fluid-particle model to study the shearing behavior of\ngranular soils under different saturation levels, ranging from the dry material\nvia the capillary bridge regime to higher saturation levels with percolating\nclusters. The full complexity of possible liquid morphologies is taken into\naccount, implying the formation of isolated arbitrary-sized liquid clusters\nwith individual Laplace pressures that evolve by liquid exchange via films on\nthe grain surface. Liquid clusters can grow in size, shrink, merge and split,\ndepending on local conditions, changes of accessible liquid and the pore space\nmorphology determined by the granular phase. This phase is represented by a\ndiscrete particle model based on Contact Dynamics, where capillary forces\nexerted from a liquid phase add to the motion of spherical particles. We study\nthe macroscopic response of the system due to an external compression force at\nvarious liquid contents with the help of triaxial shear tests. Additionally,\nthe change in liquid cluster distributions during the compression due to the\ndeformation of the pore space is evaluated close to the critical load."
    },
    {
        "anchor": "Free-Energy Functional Method for Inverse Problem of Self Assembly: A new theoretical approach is described for the inverse self-assembly\nproblem, i.e., the reconstruction of the interparticle interaction from a given\nstructure. This theory is based on the variational principle for the functional\nthat is constructed from a free energy functional in combination with Percus's\napproach [J. Percus, Phys. Rev. Lett. vol.8, 462 (1962)]. In this theory, the\ninterparticle interaction potential for the given structure is obtained as the\nfunction that maximizes the functional. As test cases, the interparticle\npotentials for two-dimensional crystals, such as square, honeycomb, and kagome\nlattices, are predicted by this theory. The formation of each target lattice\nfrom an initial random particle configuration in Monte Carlo simulations with\nthe predicted interparticle interaction indicates that the theory is\nsuccessfully applied to the test cases.",
        "positive": "Collective Thermotaxis of Thermally Active Colloids: Colloids with patchy metal coating under laser irradiation could act as local\nsources of heat due to the absorption of light. While for asymmetric colloids\nthis could induce self-propulsion, it also leads to the generation of a slowly\ndecaying temperature profile that other colloids could interact with. The\ncollective behavior of a dilute solution of such thermally active particles is\nstudied using a stochastic formulation. It is found that when the Soret\ncoefficient is positive, the system could be described in stationary-state by\nthe nonlinear Poisson-Boltzmann equation and could adopt density profiles with\nsignificant depletion in the middle region when confined. For colloids with\nnegative Soret coefficient, the system can be described as a dissipative\nequivalent of a gravitational system. It is shown that in this case the\nthermally active colloidal solution could undergo an instability at a critical\nlaser intensity, which has similarities to supernova explosion."
    },
    {
        "anchor": "Flow behavior of colloidal rod-like viruses in the nematic phase: The behavior of a colloidal suspension of rod-like {\\it fd} viruses in the\nnematic phase, subjected to steady state and transient shear flows is studied.\nThe monodisperse nature of these rods combined with relatively small textural\ncontribution to the overall stress make this a suitable model system to\ninvestigate the effects of flow on the non-equilibrium phase diagram. Transient\nrheological experiments are used to determine the critical shear rates at which\ndirector tumbling, wagging and flow-aligning occurs. The present model system\nenables us to study the effect of rod concentration on these transitions. The\nresults are in quantitatively agreement with the Doi-Edwards-Hess model.\nMoreover, we observe that there is a strong connection between the dynamic\ntransitions and structure formation, which is not incorporated in theory.",
        "positive": "Time dependent elastic response to a local shear transformation in\n  amorphous solids: The elastic response of a two-dimensional amorphous solid to induced local\nshear transformations, which mimic the elementary plastic events occurring in\ndeformed glasses, is investigated via Molecular Dynamics simulations. We show\nthat for different spatial realizations of the transformation, despite relative\nfluctuations of order one, the long time equilibrium response averages out to\nthe prediction of the Eshelby inclusion problem for a continuum elastic medium.\nWe characterize the effects of the underlying dynamics on the propagation of\nthe elastic signal. A crossover from a propagative transmission in the case of\nweakly-damped dynamics to a diffusive transmission for strong damping is\nevidenced. In the latter case, the full time dependent elastic response is in\nagreement with the theoretical prediction, obtained by solving the diffusion\nequation for the displacement field in an elastic medium."
    },
    {
        "anchor": "The Geometry of the Cholesteric Phase: We propose a construction of a cholesteric pitch axis for an arbitrary\nnematic director field as an eigenvalue problem. Our definition leads to a\nFrenet-Serret description of an orthonormal triad determined by this axis, the\ndirector, and the mutually perpendicular direction. With this tool we are able\nto compare defect structures in cholesterics, biaxial nematics, and smectics.\nThough they all have similar ground state manifolds, the defect structures are\ndifferent and cannot be, in general, translated from one phase to the other.",
        "positive": "Machine Learning Assisted Characterization of Labyrinthine Pattern\n  Transitions: We present a comprehensive approach to characterizing labyrinthine structures\nthat often emerge as a final steady state in pattern forming systems. We employ\nmachine learning based pattern recognition techniques to identify the types and\nlocations of topological defects of the local stripe ordering to augment\nconventional Fourier analysis. A pair distribution function analysis of the\ntopological defects reveals subtle differences between labyrinthine structures\nwhich are beyond the conventional characterization methods. We utilize our\napproach to highlight a clear morphological transition between two zero-field\nlabyrinthine structures in single crystal Bi substituted Yttrium Iron Garnet\nfilms. An energy landscape picture is proposed to understand the athermal\ndynamics that governs the observed morphological transition. Our work\ndemonstrates that machine learning based recognition techniques enable novel\nstudies of rich and complex labyrinthine type structures universal to many\npattern formation systems."
    },
    {
        "anchor": "Chromatin dynamics: Nucleosomes go mobile through twist defects: We study the spontaneous ''sliding'' of histone spools (nucleosomes) along\nDNA as a result of thermally activated single base pair twist defects. To this\nend we map the system onto a suitably extended Frenkel-Kontorova model.\nCombining results from several recent experiments we are able to estimate the\nnucleosome mobility without adjustable parameters. Our model shows also how the\nlocal mobility is intimately linked to the underlying base pair sequence.",
        "positive": "Using Nonlinear Response to Estimate the Strength of an Elastic Network: Disordered networks of fragile elastic elements have been proposed as a model\nof inner porous regions of large bones [Gunaratne et.al., cond-mat/0009221,\nhttp://xyz.lanl.gov]. It is shown that the ratio $\\Gamma$ of responses of such\na network to static and periodic strain can be used to estimate its ultimate\n(or breaking) stress. Since bone fracture in older adults results from the\nweakening of porous bone, we discuss the possibility of using $\\Gamma$ as a\nnon-invasive diagnostic of osteoporotic bone."
    },
    {
        "anchor": "Anisotropic nonlinear elasticity in a spherical bead pack: influence of\n  the fabric anisotropy: Stress-strain measurements and ultrasound propagation experiments in glass\nbead packs have been simultaneously conducted to characterize the\nstress-induced anisotropy under uniaxial loading. These measurements, realized\nrespectively with finite and incremental deformations of the granular assembly,\nare analyzed within the framework of the effective medium theory based on the\nHertz-Mindlin contact theory. Our work shows that both compressional and shear\nwave velocities and consequently the incremental elastic moduli agree fairly\nwell with the effective medium model by Johnson et al. [J. Appl. Mech. 65, 380\n(1998)], but the anisotropic stress ratio resulting from finite deformation\ndoes not at all. As indicated by numerical simulations, the discrepancy may\narise from the fact that the model doesn't properly allow the grains to relax\nfrom the affine motion approximation. Here we find that the interaction nature\nat the grain contact could also play a crucial role for the relevant prediction\nby the model; indeed, such discrepancy can be significantly reduced if the\nfrictional resistance between grains is removed. Another main experimental\nfinding is the influence of the inherent anisotropy of granular packs, realized\nby different protocols of the sample preparation. Our results reveal that\ncompressional waves are more sensitive to the stress-induced anisotropy,\nwhereas the shear waves are more sensitive to the fabric anisotropy, not being\naccounted in analytical effective medium models.",
        "positive": "Unified study of glass and jamming rheology in soft particle systems: We explore numerically the shear rheology of soft repulsive particles at\nlarge volume fraction. The interplay between viscous dissipation and thermal\nmotion results in multiple rheological regimes encompassing Newtonian,\nshear-thinning and yield stress regimes near the `colloidal' glass transition\nwhen thermal fluctuations are important, crossing over to qualitatively similar\nregimes near the `jamming' transition when dissipation dominates. In the\ncrossover regime, glass and jamming sectors coexist and give complex flow\ncurves. Although glass and jamming limits are characterized by similar\nmacroscopic flow curves, we show that they occur over distinct time and stress\nscales and correspond to distinct microscopic dynamics. We propose a simple\nrheological model describing the glass to jamming crossover in the flow curves,\nand discuss the experimental implications of our results."
    },
    {
        "anchor": "Anisotropy and memory during cage breaking events close to a wall: The slow dynamics in a glassy hard-sphere system is dominated by cage\nbreaking events, i.e., rearrangements where a particle escapes from the cage\nformed by its neighboring particles. We study such events for an overdamped\ncolloidal system by the means of Brownian dynamics simulations. While it is\ndifficult to relate cage breaking events to structural mean field results in\nbulk, we show that the microscopic dynamics of particles close to a wall can be\nrelated to the anisotropic two-particle density. In particular, we study\ncage-breaking trajectories, mean forces on a tracked particle, and the impact\nof the history of trajectories. Based on our simulation results, we further\nconstruct two different one-particle random-walk models - one without and one\nwith memory incorporated - and find the local anisotropy and the\nhistory-dependence of particles as crucial ingredients to describe the escape\nfrom a cage. Finally, our detailed study of a rearrangement event close to a\nwall not only reveals the memory effect of cages, but leads to a deeper insight\ninto the fundamental mechanisms of glassy dynamics.",
        "positive": "Shape Bifurcation of a Spherical Dielectric Elastomer Balloon under the\n  Actions of Internal Pressure and Electric Voltage: Under the actions of internal pressure and electric voltage, a spherical\ndielectric elastomer balloon usually keeps a sphere during its deformation,\nwhich has also been assumed in many previous studies. In this article, using\nlinear perturbation analysis, we demonstrate that a spherical dielectric\nelastomer balloon may bifurcate to a non-spherical shape under certain\nelectromechanical loading conditions. We also show that with a non-spherical\nshape, the dielectric elastomer balloon may have highly inhomogeneous electric\nfield and stress/stretch distributions, which can lead to the failure of the\nsystem. In addition, we conduct stability analysis of the dielectric elastomer\nballoon in different equilibrium configurations by evaluating its second\nvariation of free energy under arbitrary perturbations. Our analyses indicate\nthat under pressure-control and voltage-control mode, non-spherical deformation\nof the dielectric elastomer balloon is energetically unstable. However, under\ncharge-control or ideal gas mass-control mode, non-spherical deformation of the\nballoon is energetically stable."
    },
    {
        "anchor": "Cooperativity and Spatial Correlations near the Glass Transition:\n  Computer Simulation Results for Hard Spheres and Discs: We examine the dynamics of hard spheres and discs at high packing fractions\nin two and three dimensions, modeling the simplest systems exhibiting a glass\ntransition. As it is well known, cooperativity and dynamic heterogeneity arise\nas central features when approaching the glass transition from the liquid\nphase, so an understanding of their underlying physics is of great interest.\nCooperativity implies a reduction of the effective degrees of freedom, and we\ndemonstrate a simple way of quantification in terms of the strength and the\nlength scale of dynamic correlations among different particles. These\ncorrelations are obtained for different dynamical quantities $X_i(t)$ that are\nconstructed from single-particle displacements during some observation time\n$t$. Of particular interest is the dependence on $t$. Interestingly, for\nappropriately chosen $X_i(t)$ we obtain finite cooperativity in the limit $t\n\\to \\infty$.",
        "positive": "Non-equilibrium dynamics of an active colloidal \"chucker\": We report Monte Carlo simulations of the dynamics of a \"chucker\": a colloidal\nparticle which emits smaller solute particles from its surface, isotropically\nand at a constant rate k_c. We find that the diffusion constant of the chucker\nincreases for small k_c, as recently predicted theoretically. At large k_c the\nchucker diffuses more slowly due to crowding effects. We compare our simulation\nresults to those of a \"point particle\" Langevin dynamics scheme in which the\nsolute concentration field is calculated analytically, and in which\nhydrodynamic effects can be included albeit in an approximate way. By\nsimulating the dragging of a chucker, we obtain an estimate of its apparent\nmobility coefficient which violates the fluctuation-dissipation theorem. We\nalso characterise the probability density profile for a chucker which sediments\nonto a surface which either repels or absorbs the solute particles, and find\nthat the steady state distributions are very different in the two cases. Our\nsimulations are inspired by the biological example of\nexopolysaccharide-producing bacteria, as well as by recent experimental,\nsimulation and theoretical work on phoretic colloidal \"swimmers\"."
    },
    {
        "anchor": "Linear hydrodynamics and viscoelasticity of nematic elastomers: We develop a continuum theory of linear viscoelastic response in oriented\nmonodomain nematic elastomers. The expression for dissipation function is\nanalogous to the Leslie-Ericksen version of anisotropic nematic viscosity; we\npropose the relations between the anisotropic rubber moduli and new viscous\ncoefficients. A new dimensionless number is introduced, which describes the\nrelative magnitude of viscous and rubber-elastic torques. In an elastic medium\nwith an independently mobile internal degree of freedom, the nematic director\nwith its own relaxation dynamics, the model shows a dramatic decrease in the\ndynamic modulus in certain deformation geometries. The degree to which the\nstorage modulus does not altogether drop to zero is shown to be both dependent\non frequency and to be proportional to the semi-softness, the non-ideality of a\nnematic network. We consider the most interesting geometry for the\nimplementation of the theory, calculating the dynamic response to an imposed\nsimple shear and making predictions for effective moduli and (exceptionally\nhigh) loss factors.",
        "positive": "Comparative investigations of surface instabilities (\"sharkskin\") of a\n  linear and a long-chain branched polyethylene: An experimental study of the physical origin and the mechanisms of the\nsharkskin instability is presented. Extrusion flows through a slit die are\nstudied for two materials: a linear low density polyethylene (LLDPE) and a low\ndensity polyethylene (LDPE). By combining laser-Doppler velocimetry (LDV) with\nrheological measurements in both uniaxial extension and shear, the\ndistributions of tensile and shear stresses in extrusion flows are measured for\nboth materials."
    },
    {
        "anchor": "Gaussian random waves in elastic media: Similar to the Berry conjecture of quantum chaos we consider elastic analogue\nwhich incorporates longitudinal and transverse elastic displacements with\ncorresponding wave vectors. Based on that we derive the correlation functions\nfor amplitudes and intensities of elastic displacements. Comparison to numerics\nin a quarter Bunimovich stadium demonstrates excellent agreement.",
        "positive": "Comparison of a Microgel Simulation to Poisson-Boltzmann Theory: We have investigated a single charged microgel in aqueous solution with a\ncombined simulational model and Poisson-Boltzmann theory. In the simulations we\nuse a coarse-grained charged bead-spring model in a dielectric continuum, with\nexplicit counterions and full electrostatic interactions under periodic and\nnon-periodic boundary conditions. The Poisson-Boltzmann model is that of a\nsingle charged colloid confined to a spherical cell where the counterions are\nallowed to enter the uniformly charged sphere. We compare the simulational\nresults to those of the Poisson-Boltzmann solution and find good agreement,\ni.e., for the number of confined counterions within the gel. We then proceed to\ninvestigate the origin of the differences between the results these two models\ngive, and performed a variety of simulations which were designed to test for\nthe influence of charge correlations, excluded volume interactions, and thermal\nfluctuations in the strands of the gel. Our results support the applicability\nof the Poisson-Boltzman cell model to study ionic properties of small microgels\nunder dilute conditions."
    },
    {
        "anchor": "Elastic three-sphere microswimmer in a viscous fluid: We discuss the dynamics of a generalized three-sphere microswimmer in which\nthe spheres are connected by two elastic springs. The natural length of each\nspring is assumed to undergo a prescribed cyclic change. We analytically obtain\nthe average swimming velocity as a function of the frequency of the cyclic\nchange in the natural length. In the low-frequency region, the swimming\nvelocity increases with the frequency and its expression reduces to that of the\noriginal three-sphere model by Najafi and Golestanian. In the high-frequency\nregion, conversely, the average velocity decreases with increasing the\nfrequency. Such a behavior originates from the intrinsic spring relaxation\ndynamics of an elastic swimmer moving in a viscous fluid.",
        "positive": "Inertio-elastic instability in Taylor-Couette \u00b0ow of a model\n  wormlike micellar system: In this work, we use flow visualization and rheometry techniques to study the\ndynamics and evolution of secondary flows in a model wormlike micellar solution\nsheared between concentric cylinders, i.e., in a Taylor-Couette (TC) cell. The\nwormlike micellar solution studied in this work contains cetyltrimethylammonium\nbromide (CTAB) and sodium salicylate (NaSal). This system can be shear banding\nand highly elastic, non-shear banding and moderately elastic, or nearly\nNewtonian as the temperature is varied over a narrow range. The effect of\nelasticity on transitions and instabilities is probed by changing the\ntemperature over a wide range of elasticity (El<< 1, El ~1, and El>>1).\nElasticity is defined as the ratio of the Weissenberg number to the Reynolds\nnumber. For shear banding wormlike micelle solutions where El>> 1, a primary\ntransition from the base Couette flow to stationary vortices that are evenly\nspaced in the axial direction of the shear cell and are characterized by an\nasymptotic wave-length is observed. The dimensionless wave- length at the onset\nof this shear banding transition for CTAB/NaSal system turns out to be much\nlarger than those reported for other shear banding wormlike micelle systems.\nFor the same fluid at a temperature where it shear-thins but does not display\nshear banding, El~1, and for slow ramp speeds, the primary transition is to\ndistinct structures that are not stationary but rather travel in the axial\ndirection. At low elasticity (El<< 1), where the fluid behaves as a nearly\nNewtonian fluid, several transitions from purely azimuthal Couette flow to\nmodified Taylor vortex flows and finally chaotic regimes are documented. The\nbehavior in the shear-banding and non-shear-banding regimes are discussed and\ncompared with results in related systems."
    },
    {
        "anchor": "Effect of cross-coupling on the phase behavior in a biaxial nematic:\n  Insights from Monte Carlo studies: Phase sequences of the biaxial nematic liquid crystal in the interior of the\nessential triangle are studied with Wang Landau sampling. The evidence points\nto the existence of an intermediate unixial phase with low biaxiality in the\nisotropic to biaxial nematic phase sequence.",
        "positive": "Phase segregation of passive advective particles in an active medium: Localized contractile configurations or asters spontaneously appear and\ndisappear as emergent structures in the collective stochastic dynamics of\nactive polar actomyosin filaments. Passive parti- cles which (un)bind to the\nactive filaments get advected into the asters, forming transient clusters. We\nstudy the phase segregation of such passive advective scalars in a medium of\ndynamic asters, as a function of the aster density and the ratio of the rates\nof aster remodeling to particle diffusion. The dynamics of coarsening shows\nstrong violation of Porod behaviour, suggesting diffuse interfaces. The phase\nsegregated steady state shows strongly fluctuations characterized by\nmultiscaling and in- termittency. We expect these unique nonequilibrium\nfeatures to manifest in the actin-dependent molecular clustering at the cell\nsurface."
    },
    {
        "anchor": "An optical fiber based interferometer to measure velocity profiles in\n  sheared complex fluids: We describe an optical fiber based interferometer to measure velocity\nprofiles in sheared complex fluids using Dynamic Light Scattering (DLS). After\na review of the theoretical problem of DLS under shear, a detailed description\nof the setup is given. We outline the various experimental difficulties induced\nby refraction when using a Couette cell. We also show that homodyne DLS is not\nwell suited to measure quantitative velocity profiles in narrow-gap Couette\ngeometries. On the other hand, the heterodyne technique allows us to determine\nthe velocity field inside the gap of a Couette cell. All the technical features\nof the setup, namely its spatial resolution ($\\approx 50$--$100 \\mu$m) and its\ntemporal resolution ($\\approx 1$ s per point, $\\approx 1$ min per profile) are\ndiscussed, as well as the calibration procedure with a Newtonian fluid. As\nbriefly shown on oil-in-water emulsions, such a setup permits one to record\nboth velocity profiles and rheological data simultaneously",
        "positive": "Electrophoresis of ions and electrolyte conductivity: from bulk to\n  nanochannels: When electrolyte solutions are confined in micro- and nanochannels their\nconductivity is significantly different from those in a bulk phase. Here we\nrevisit the theory of this phenomenon by focusing attention on the reduction in\nthe ion mobility with the concentration of salt and a consequent impact to the\nconductivity of a monovalent solution, from bulk to confined in a narrow slit.\nWe first give a systematic treatment of electrophoresis of ions and obtain\nequations for their zeta potentials and mobilities. The latter are then used to\nobtain a simple expression for a bulk conductivity, which is valid in a\nconcentration range up to a few molars and more accurate than prior analytic\ntheories. By extending the formalism to the electrolyte solution in the charged\nchannel the equations describing the conductivity in different modes are\npresented. They can be regarded as a generalization of prior work on the\nchannel conductivity to a more realistic case of a nonzero reduction of the\nzeta potential and electrophoretic mobility of ions with salt concentration.\nOur analysis provides a framework for interpreting measurements on the\nconductivity of electrolyte solutions in the bulk and in narrow channels."
    },
    {
        "anchor": "Colloidal Flying Carpets: DNA plays a special role in polymer science not just because of the highly\nselective recognition of complementary single DNA strands but also because\nbacteria can express DNA chains that are very long yet perfectly monodisperse.\nThe latter reason makes long DNA molecules widely used as model systems in\npolymer science. Here, we report the unusual self-assembly that takes place in\nsystems of colloids coated with very long double-stranded DNA. In particular,\nwe find that colloids coated with such long DNA can assemble into unique\nfloating crystalline monolayers. Floating colloidal structures have potentially\ninteresting applications as such ordered structures can be assembled in one\nlocation and then deposited somewhere else. This would open the way to the\nassembly of multi-component, layered colloidal crystals.",
        "positive": "Pattern evolution in bending dielectric-elastomeric bilayers: We propose theoretical and numerical analyses of smart bending deformation of\na dielectric-elastic bilayer in response to a voltage, based on the nonlinear\ntheory of electro-elasticity and the associated linearized incremental field\ntheory. We reveal that the mechanism allowing the bending angle of the bilayer\ncan be tuned by adjusting the applied voltage. Furthermore, we investigate how\nmuch can the bilayer be bent before it loses its stability by buckling when one\nof its faces is under too much compression. We find that the physical\nproperties of the two layers must be selected to be of the same order of\nmagnitude to obtain a consequent bending without encountering buckling. If\nrequired, the wrinkles can be designed to appear on either the inner or the\nouter bent surface of the buckled bilayer. We validate the results through\ncomparison with those of the classical elastic problem."
    },
    {
        "anchor": "Light Scattering from Nonequilibrium Concentration Fluctuations in a\n  Polymer solution: We have performed light-scattering measurements in dilute and semidilute\npolymer solutions of polystyrene in toluene when subjected to stationary\ntemperature gradients. Five solutions with concentrations below and one\nsolution with a concentration above the overlap concentration were\ninvestigated. The experiments confirm the presence of long-range nonequilibrium\nconcentration fluctuations which are proportional to $(\\nabla T)^2/k^4$, where\n$\\nabla T$ is the applied temperature gradient and $k$ is the wave number of\nthe fluctuations. In addition, we demonstrate that the strength of the\nnonequilibrium concentration fluctuations, observed in the dilute and\nsemidilute solution regime, agrees with theoretical values calculated from\nfluctuating hydrodynamics. Further theoretical and experimental work will be\nneeded to understand nonequilibrium fluctuations in polymer solutions at higher\nconcentrations.",
        "positive": "Disclinations, e-cones, and their interactions in extensible sheets: We investigate the nucleation, growth, and spatial organization of\ntopological defects with a ribbon shaped elastic sheet which is stretched and\ntwisted. Singularities are found to spontaneously arrange in a triangular\nlattice in the form of vertices connected by stretched ridges that result in a\nself-rigidified structure. The vertices are shown to be negative disclinations\nor e-cones which occur in sheets with negative Gaussian curvature, in contrast\nwith d-cones in sheets with zero-Gaussian curvature. We find the growth of the\nwrinkled width of the ribbon to be consistent with a far-from-threshold\napproach assuming a compression-free base state. The system is found to show a\ntransition from a regime where the wavelength is given by the ribbon geometry,\nto where it is given by its elasticity as a function of the ratio of the\napplied tension to the elastic modulus and cross-sectional area of the ribbon."
    },
    {
        "anchor": "Dynamics of a massive intruder in a homogeneously driven granular fluid: A massive intruder in a homogeneously driven granular fluid, in dilute\nconfigurations, performs a memory-less Brownian motion with drag and\ntemperature simply related to the average density and temperature of the fluid.\nAt volume fraction $\\sim 10-50%$ the intruder's velocity correlates with the\nlocal fluid velocity field: such situation is approximately described by a\nsystem of coupled linear Langevin equations equivalent to a generalized\nBrownian motion with memory. Here one may verify the breakdown of the\nFluctuation-Dissipation relation and the presence of a net entropy flux - from\nthe fluid to the intruder - whose fluctuations satisfy the Fluctuation\nRelation.",
        "positive": "Particle Diffusivity and Free-Energy Profiles in Inhomogeneous Hydrogel\n  Systems from Time-Resolved Penetration Profiles: A combined experimental/theoretical method to simultaneously determine\ndiffusivity and free-energy profiles of particles that penetrate into\ninhomogeneous hydrogel systems is presented. As the only input, arbitrarily\nnormalized concentration profiles from fluorescence intensity data of labeled\ntracer particles for different penetration times are needed. The method is\napplied to dextran molecules of varying size which penetrate into hydrogels of\npolyethylene-glycol (PEG) chains with different lengths that are covalently\ncross-linked by hyperbranched polyglycerol (hPG) hubs. Extracted dextran bulk\ndiffusivities agree well with fluorescence correlation spectroscopy data\nobtained separately. Scaling laws for dextran diffusivities and free energies\ninside the hydrogel are identified as a function of the dextran mass. An\nelastic free-volume model that includes dextran as well as PEG linker\nflexibility describes the repulsive dextran-hydrogel interaction free energy,\nwhich is of steric origin, quantitatively and furthermore suggests that the\nhydrogel mesh-size distribution is rather broad and particle penetration is\ndominated by large hydrogel pores. Particle penetration into hydrogels is for\nsteric particle-hydrogel interactions thus suggested to be governed by an\nelastic size-filtering mechanism that involves the tail of the hydrogel\npore-size distribution."
    },
    {
        "anchor": "Ratchet Effects in Active Matter Systems: Ratchet effects can arise for single or collectively interacting Brownian\nparticles on an asymmetric substrate when a net dc transport is produced by an\nexternally applied ac driving force or by periodically flashing the substrate.\nRecently, a new class of active ratchet systems has been realized through the\nuse of active matter, which are self-propelled units that can be biological or\nnon-biological in nature. When active materials such as swimming bacteria\ninteract with an asymmetric substrate, a net dc directed motion can arise even\nwithout external driving, opening a wealth of possibilities such as sorting,\ncargo transport, or micromachine construction. We review the current status of\nactive matter ratchets for swimming bacteria, cells, active colloids, and\nswarming models, focusing on the role of particle-substrate interactions. We\ndescribe ratchet reversals produced by collective effects and the use of active\nratchets to transport passive particles. We discuss future directions including\ndeformable substrates or particles, the role of different swimming modes,\nvaried particle-particle interactions, and non-dissipative effects.",
        "positive": "Hydrogen bond dynamics at the glass transition: The glass transition in hydrogen-bonded glass formers differs from the glass\ntransition in other glass formers. The Eshelby rearrangements of the highly\nviscous flow are superimposed by strongly asymmetric hydrogen bond rupture\nprocesses, responsible for the excess wing. Their influence on the shear\nrelaxation spectrum is strong in glycerol and close to zero in PPE, reflecting\nthe strength of the hydrogen bond contribution to the high frequency shear\nmodulus. A recent theory of the highly viscous flow enables a quantitative\ncommon description of the relaxation spectra in shear, linear and non-linear\ndielectrics, and heat capacity."
    },
    {
        "anchor": "Lattice Boltzmann simulations of drying suspensions of soft particles: The ordering of particles in the drying process of a colloidal suspension is\ncrucial in determining the properties of the resulting film. For example,\nmicroscopic inhomogeneities can lead to the formation of cracks and defects\nthat can deteriorate the quality of the film considerably. This type of problem\nis inherently multiscale and here we study it numerically, using our recently\ndeveloped method for the simulation of soft polymeric capsules in\nmulticomponent fluids. We focus on the effect of the particle softness on the\nfilm microstructure during the drying phase and how it relates to the formation\nof defects. We quantify the order of the particles by measuring both the\nVoronoi entropy and the isotropic order parameter. Surprisingly, both\nobservables exhibit a non-monotonic behaviour when the softness of the\nparticles is increased. We further investigate the correlation between the\ninterparticle interaction and the change in the microstructure during the\nevaporation phase. We observe that the rigid particles form chain-like\nstructures that tend to scatter into small clusters when the particle softness\nis increased.",
        "positive": "Elasticity of thin rods with spontaneous curvature and torsion - beyond\n  geometrical lines: We study three-dimensional deformations of thin inextensible elastic rods\nwith non-vanishing spontaneous curvature and torsion. In addition to the usual\ndescription in terms of curvature and torsion which considers only the\nconfiguration of the centerline of the rod, we allow deformations that involve\nthe rotation of the rod's cross-section around its centerline. We derive new\nexpressions for the mechanical energy and for the force and moment balance\nconditions for the equilibrium of a rod under the action of arbitrary external\nloads. Several illustrative examples are studied and the connection between our\nresults and recent experiments on stretching of supercoiled DNA molecules is\ndiscussed."
    },
    {
        "anchor": "Oscillatory chiral flows in confined active fluids with obstacles: An active colloidal fluid comprised of self-propelled spinning particles\ninjecting energy and angular momentum at the microscale demonstrates\nspontaneous collective states that range from flocks to coherent vortices.\nDespite their seeming simplicity, the emergent far-from-equilibrium behavior of\nthese fluids remains poorly understood, presenting a challenge to the design\nand control of next-generation active materials. When confined in a ring, such\nso-called polar active fluids acquire chirality once the spontaneous flow\nchooses a direction. In a perfect ring, this chirality is indefinitely\nlong-lived. Here, we combine experiments on self-propelled colloidal Quincke\nrollers and mesoscopic simulations of continuum Toner-Tu equations to explore\nhow such chiral states can be controlled and manipulated by obstacles. For\ndifferent obstacle geometries three dynamic steady states have been realized:\nlong-lived chiral flow, an apolar state in which the flow breaks up into\ncounter-rotating vortices and an unconventional collective state with flow\nhaving an oscillating chirality. The chirality reversal proceeds through the\nformation of intermittent vortex chains in the vicinity of an obstacle. We\ndemonstrate that the frequency of collective states with oscillating chirality\ncan be tuned by obstacle parameters. We vary obstacle shapes to design chiral\nstates that are independent of initial conditions. Building on our findings, we\nrealize a system with two triangular obstacles that force the active fluid\ntowards a state with a density imbalance of active particles across the ring.\nOur results demonstrate how spontaneous polar active flows in combination with\nsize and geometry of scatterers can be used to control dynamic patterns of\npolar active liquids for materials design.",
        "positive": "Large Mpemba-like effect in a gas of inelastic rough hard spheres: We report the emergence of a giant Mpemba effect in the uniformly heated gas\nof inelastic rough hard spheres: The initially hotter sample may cool sooner\nthan the colder one, even when the initial temperatures differ by more than one\norder of magnitude. In order to understand this behavior, it suffices to\nconsider the simplest Maxwellian approximation for the velocity distribution in\na kinetic approach. The largeness of the effect stems from the fact that the\nrotational and translational temperatures, which obey two coupled evolution\nequations, are comparable. Our theoretical predictions agree very well with\nmolecular dynamics and direct simulation Monte Carlo data."
    },
    {
        "anchor": "High-resolution dielectric study reveals pore size-dependent\n  orientational order of a discotic liquid crystal confined in tubular\n  nanopores: We report a high-resolution dielectric study on a pyrene-based discotic\nliquid crystal (DLC) in the bulk state and confined in parallel tubular\nnanopores of monolithic silica and alumina membranes. The positive dielectric\nanisotropy of the DLC molecule at low frequencies (in the quasi-static case)\nallows us to explore the thermotropic collective orientational order. A face-on\narrangement of the molecular discs on the pore walls and a corresponding radial\narrangement of the molecules is found. In contrast to the bulk, the\nisotropic-to-columnar transition of the confined DLC is continuous, shifts with\ndecreasing pore diameter to lower temperatures and exhibits a pronounced\nhysteresis between cooling and heating. These findings corroborate conclusions\nfrom previous neutron and X-ray scattering experiments as well as optical\nbirefringence measurements. Our study also indicates that the relative simple\ndielectric technique presented here is a quite efficient method in order to\nstudy the thermotropic orientational order of DLC based nanocomposites.",
        "positive": "Absorption spectrum of Ca atoms attached to $^4$He nanodroplets: Within density functional theory, we have obtained the structure of $^4$He\ndroplets doped with neutral calcium atoms. These results have been used, in\nconjunction with newly determined {\\it ab-initio} $^1\\Sigma$ and $^1\\Pi$ Ca-He\npair potentials, to address the $4s4p$ $^1$P$_1 \\leftarrow 4s^2$ $^1$S$_0$\ntransition of the attached Ca atom, finding a fairly good agreement with\nabsorption experimental data. We have studied the drop structure as a function\nof the position of the Ca atom with respect of the center of mass of the helium\nmoiety. The interplay between the density oscillations arising from the helium\nintrinsic structure and the density oscillations produced by the impurity in\nits neighborhood plays a role in the determination of the equilibrium state,\nand hence in the solvation properties of alkaline earth atoms. In a case of\nstudy, the thermal motion of the impurity within the drop surface region has\nbeen analyzed in a semi-quantitative way. We have found that, although the\natomic shift shows a sizeable dependence on the impurity location, the thermal\neffect is statistically small, contributing by about a 10% to the line\nbroadening. The structure of vortices attached to the calcium atom has been\nalso addressed, and its effect on the calcium absorption spectrum discussed. At\nvariance with previous theoretical predictions, we conclude that spectroscopic\nexperiments on Ca atoms attached to $^4$He drops will be likely unable to\ndetect the presence of quantized vortices in helium nanodrops."
    },
    {
        "anchor": "Stochastic Rotation Dynamics simulations of wetting multi-phase flows: Multi-color Stochastic Rotation Dynamics (SRDmc) has been introduced by Inoue\net al. as a particle based simulation method to study the flow of emulsion\ndroplets in non-wetting microchannels. In this work, we extend the multi-color\nmethod to also account for different wetting conditions. This is achieved by\nassigning the color information not only to fluid particles but also to virtual\nwall particles that are required to enforce proper no-slip boundary conditions.\nTo extend the scope of the original SRDmc algorithm to e.g. immiscible\ntwo-phase flow with viscosity contrast we implement an angular momentum\nconserving scheme (SRDmc+). We perform extensive benchmark simulations to show\nthat a mono-phase SRDmc fluid exhibits bulk properties identical to a standard\nSRD fluid and that SRDmc fluids are applicable to a wide range of immiscible\ntwo-phase flows. To quantify the adhesion of a SRDmc+ fluid in contact to the\nwalls we measure the apparent contact angle from sessile droplets in mechanical\nequilibrium. For a further verification of our wettability implementation we\ncompare the dewetting of a liquid film from a wetting stripe to experimental\nand numerical studies of interfacial morphologies on chemically structured\nsurfaces.",
        "positive": "Active particles methods towards modeling in science and society: This paper is a first step to chase the ambitious objective of developing a\nmathmatical theory of living systems. The contents refer modeling large systems\nof interacting living entities with the aim of describing their collective\nbehaviors by differential models. The contents is in three parts. Firstly, we\nderive the mathematical method; subsequently, we show how the method can be\napplied in a number of case studies related to well defined living systems and\nfinally, we look ahead to research perspectives focusing both on mathematical\nmethods and further applications."
    },
    {
        "anchor": "Defects in active nematics: algorithms for identification and tracking: The growing interest in active nematics and the emerging evidence of the\nrelevance of topological defects in biology asks for reliable data analysis\ntools to identify, classify and track such defects in simulation and microscopy\ndata. We here provide such tools and demonstrate on two examples, on an active\nturbulent state in an active nematodynamic model and on emerging nematic order\nin a multi-phase field model, the possibility to compare statistical data on\ndefect velocities with experimental results. The considered tools, which are\nphysics based and data driven, are compared with each other.",
        "positive": "Slow dynamics of salol: a pressure and temperature dependent light\n  scattering study: We study the slow dynamics of salol by varying both temperature and pressure\nusing photon correlation spectroscopy and pressure-volume-temperature\nmeasurements, and compare the behavior of the structural relaxation time with\nequations derived within the Adam-Gibbs entropy theory and the Cohen-Grest free\nvolume theory. We find that pressure dependent data are crucial to assess the\nvalidity of these model equations. Our analysis supports the entropy-based\nequation, and estimates the configurational entropy of salol at ambient\npressure ? 70% of the excess entropy. Finally, we investigate the evolution of\nthe shape of the structural relaxation process, and find that a\ntime-temperature-pressure superposition principle holds over the range\ninvestigated."
    },
    {
        "anchor": "Conformational Collapse of Surface-Bound Helical Filaments: Chiral polymers are ubiquitous in nature and in the cellular context they are\noften found in association with membranes. Here we show that surface bound\npolymers with an intrinsic twist and anisotropic bending stiffness can exhibit\na sharp continuous phase transition between states with very different\neffective persistence lengths as the binding affinity is increased. Above a\ncritical value for the binding strength, determined solely by the torsional\nmodulus and intrinsic twist rate, the filament can exist in a zero twist,\nsurface bound state with a homogeneous stiffness. Below the critical binding\nstrength, twist walls proliferate and function as weak or floppy joints that\nsharply reduce the effective persistence length that is measurable on long\nlengthscales. The existence of such dramatically different conformational\nstates has implications for both biopolymer function {\\it in vivo} and for\nexperimental observations of such filaments {\\it in vitro}.",
        "positive": "Reconnection of vortex filaments and Kolmogorov spectrum: The energy spectrum of the 3D velocity field, induced by collapsing vortex\nfilaments is studied. One of the aims of this work is to clarify the appearance\nof the Kolmogorov type energy spectrum $E(k)\\varpropto k^{-5/3}$, observed in\nmany numerical works on discrete vortex tubes (quantized vortex filaments in\nquantum fluids). Usually, explaining classical turbulent properties of quantum\nturbulence, the model of vortex bundles, is used. This model is necessary to\nmimic the vortex stretching, which is responsible for the energy transfer in\nclassical turbulence. In our consideration we do not appeal to the possible\n\"bundle arrangement\" but explore alternative idea that the turbulent spectra\nappear from singular solution, which describe the collapsing line at moments of\nreconnection. One more aim is related to an important and intensively discussed\ntopic - a role of hydrodynamic collapse in the formation of turbulent spectra.\nWe demonstrated that the specific vortex filament configuration generated the\nspectrum $E(k)$ close to the Kolmogorov dependence and discussed the reason for\nthis as well as the reason for deviation. We also discuss the obtained results\nfrom point of view of the both classical and quantum turbulence."
    },
    {
        "anchor": "Effects of chemical and geometric micro-structures on crystallization of\n  surface droplets during solvent exchange: In this work, we investigate crystallization from droplets formed on\nmicro-patterned surfaces. By solvent exchange in a micro-chamber, a ternary\nsolution consisting of a model compound beta-alanine, water, and isopropanol,\nwas displaced by a flow of isopropanol. In the process, oiling-out droplets\nformed and crystallized. Our results showed that the shape and size of the\ncrystals on micro-patterned surfaces could be simply mediated by the flow\nconditions of solvent exchange. Varying flow rate, concentration, or channel\nheight led to the formation of a thin film with micro-holes, connected network\nof crystals, or small diamond-shaped crystals. Rough micro-structures on the\nsurface allowed the easy detachment of crystals from the surface. Beyond\noiling-out crystallization, we demonstrated that the crystal formation from\nanother solute dissolved in the droplets could be triggered by solvent\nexchange. The length of crystal fibers after the solvent exchange process was\nshorter at a faster flow rate. This study may provide further understanding to\neffectively obtain crystallization from surface droplets through the solvent\nexchange approach.",
        "positive": "Quantum tunneling of three-spine solitons through excentric barriers: Macromolecular protein complexes catalyze essential physiological processes\nthat sustain life. Various interactions between protein subunits could increase\nthe effective mass of certain peptide groups, thereby compartmentalizing\nprotein $\\alpha$-helices. Here, we study the differential effects of applied\nmassive barriers upon the soliton-assisted energy transport within proteins. We\ndemonstrate that excentric barriers, localized onto a single spine in the\nprotein $\\alpha$-helix, reflect or trap three-spine solitons as effectively as\nconcentric barriers with comparable total mass. Furthermore, wider protein\nsolitons, whose energy is lower, require heavier massive barriers for soliton\nreflection or trapping. Regulation of energy transport, delivery and\nutilization at protein active sites could thus be achieved through control of\nthe soliton width, or of the effective mass of the protein subunits."
    },
    {
        "anchor": "First-order virial expansion of short-time diffusion and sedimentation\n  coefficients of permeable particles suspensions: For suspensions of permeable particles, the short-time translational and\nrotational self-diffusion coefficients, and collective diffusion and\nsedimentation coefficients are evaluated theoretically. An individual particle\nis modeled as a uniformly permeable sphere of a given permeability, with the\ninternal solvent flow described by the Debye-Bueche-Brinkman equation. The\nparticles are assumed to interact non-hydrodynamically by their excluded\nvolumes. The virial expansion of the transport properties in powers of the\nvolume fraction is performed up to the two-particle level. The first-order\nvirial coefficients corresponding to two-body hydrodynamic interactions are\nevaluated with very high accuracy by the series expansion in inverse powers of\nthe inter-particle distance. Results are obtained and discussed for a wide\nrange of the ratio, x, of the particle radius to the hydrodynamic screening\nlength inside a permeable sphere. It is shown that for x >= 10, the virial\ncoefficients of the transport properties are well-approximated by the\nhydrodynamic radius (annulus) model developed by us earlier for the effective\nviscosity of porous-particle suspensions.",
        "positive": "Orientational dynamics of anisotropic colloidal particles in a planar\n  extensional flow: Suspensions of anisotropic particles are commonly encountered in a wide\nspectrum of applications, including industrial and architectural coatings,\ntargeted drug delivery and manufacturing of fiber-reinforced composites. A\ngrand challenge in the field of chemical and material processing is robust\nproduction of strongly aligned fibers at the microscopic level, as this is\nroutinely linked with enhanced mechanical properties at the macroscopic level.\nWhile the investigation of the microstructure of anisotropic colloids in shear\nflows has garnered a lot of theoretical and experimental attention, the case of\nextensional flow remains poorly understood due to several experimental\nchallenges. In this article, we present a theoretical framework for predicting\nthe steady and transient orientations of anisotropic particles in a flowing\nliquid undergoing precisely defined steady and time-dependent planar\nextensional flow at the stagnation point of a Stokes trap device. In\nparticular, we analytically solve the Fokker-Planck equation for estimating the\nprobability distribution function describing the orientation dynamics of\nrod-like objects as a function of flow strength (Peclet number, Pe) and probing\nfrequency (Deborah number, De). The theoretical results are compared with\nrecent experiments and reasonable agreement is found. We also discuss the\nchallenges involved in obtaining a full closed-form solution for the transient\ndynamics of anisotropic particles in oscillatory time-dependent extensional\nflow. Overall, our theoretical framework provides a way to compare the\norientation dynamics of rod-like particles with experiments that have been\nperformed using a new experimental technique involving the Stokes trap and\nprecise flow-control over the orientation of particles."
    },
    {
        "anchor": "Study of interdomain boundary in diamagnetic domain structure in\n  beryllium: At low temperatures, in strong magnetic fields, the formation of a\nnon-uniform magnetisation is possible in a single-crystal metal sample whose\ndemagnetising factor along the field is close to unity. Namely, so-called\nCondon diamagnetic domain structure arises and disappears periodically with\nmagnetic field. In this paper, the diamagnetic domain structure in beryllium\nsingle crystalis analysed. Directly, existence of diamagnetic domains in that\nsample was observed earlier by the muon spin precession (mSR) resonance peak\nsplitting. A method is described that allows to calculate quantitative\ncharacteristics of the interdomain boundary using the muon histograms. The\ntechnique is based on the Marquardt minimisation procedure that has been\nmodified in order to reduce the influence of noise on iterations convergence.\nBoundary volume fraction was calculated.",
        "positive": "Shifted forces in molecular dynamics: Simulations involving the Lennard-Jones potential usually employ a cut-off at\n$r=2.5\\sigma$. This paper investigates the possibility of reducing the cut-off.\nTwo different cut-off implementations are compared, the standard shifted\npotential cut-off and the less commonly used shifted forces cut-off. The first\nhas correct forces below the cut-off, whereas the shifted forces cut-off\nmodifies Newton's equations at all distances. The latter is nevertheless\nsuperior; we find that for most purposes realistic simulations may be obtained\nusing a shifted-forces cut-off at $r=1.5\\sigma$, even though the pair force is\nhere 30 times larger than at $r=2.5\\sigma$."
    },
    {
        "anchor": "Roadmap to the morphological instabilities of a stretched twisted ribbon: We address the mechanics of an elastic ribbon subjected to twist and tensile\nload. Motivated by the classical work of Green and a recent experiment that\ndiscovered a plethora of morphological instabilities, we introduce a\ncomprehensive theoretical framework through which we construct a 4D phase\ndiagram of this basic system, spanned by the exerted twist and tension, as well\nas the thickness and length of the ribbon. Different types of instabilities\nappear in various \"corners\" of this 4D parameter space, and are addressed\nthrough distinct types of asymptotic methods. Our theory employs three\ninstruments, whose concerted implementation is necessary to provide an\nexhaustive study of the various parameter regimes: (i) a covariant form of the\nF\\\"oppl-von K\\'arm\\'an (cFvK) equations to the helicoidal state - necessary to\naccount for the large deflection of the highly-symmetric helicoidal shape from\nplanarity, and the buckling instability of the ribbon in the transverse\ndirection; (ii) a far from threshold (FT) analysis - which describes a state in\nwhich a longitudinally-wrinkled zone expands throughout the ribbon and allows\nit to retain a helicoidal shape with negligible compression; (iii) finally, we\nintroduce an asymptotic isometry equation that characterizes the energetic\ncompetition between various types of states through which a twisted ribbon\nbecomes strainless in the singular limit of zero thickness and no tension.",
        "positive": "Quantum Coherent Atomic Tunneling between Two Trapped Bose-Einstein\n  Condensates: We study the coherent atomic tunneling between two zero-temperature\nBose-Einstein condensates (BEC) confined in a double-well magnetic trap. Two\nGross-Pitaevskii equations for the self-interacting BEC amplitudes, coupled by\na transfer matrix element, describe the dynamics in terms of the inter-well\nphase-difference and population imbalance. In addition to the anharmonic\ngeneralization of the familiar $ac$ Josephson effect and plasma oscillations\noccurring in superconductor junctions, the non-linear BEC tunneling dynamics\nsustains a self-maintained population imbalance: a novel \"macroscopic quantum\nself-trapping effect\"."
    },
    {
        "anchor": "Surface Wetting Study via Pseudocontinuum Modeling: Accurate estimation of surface wettability for various degrees of\nhydrophobicity becomes increasingly important in the molecular design of\nmembrane. In this paper, we develop simple yet physically realistic model for\nestimating contact angle via hybridizing molecular dynamics and pseudocontinuum\ntheory. Molecular dynamics simulations were carried out to compute the\nmacro-scale contact angle between a water droplet and smooth walls from the\nnanoscale calculations. A macro-level droplet including countless degrees of\nfreedom due to an infinite number of molecules is impossible to be studied\ndirectly via atomistic simulations. To resolve this issue, we employed two\napproaches consisting of the pseudocontinuum approximation and the modified\nYoung-Laplace equation. The former involves the 9-3 Lennard-Jones (L-J)\npotential and can drastically reduce the degrees of freedom in molecular\nsimulations, while the latter relates the mesoscale contact angle to the\nrealistic one. We altered different parameters including the liquid-surface\npotential characteristics and the temperature, and calculated the water contact\nangle by leveraging the mass density profile fitting method to predict the\nbroad spectrum of hydrophobic and hydrophilic substrates. The computational\nresults were compared with the experimental data for various materials\nincluding graphite, silicon, and metals. This study suggests that\npseudocontinuum modeling is an accurate approach to probe surface wettability\nfor various processes at a low computational cost.",
        "positive": "Flexoelectricity and pattern formation in nematic liquid crystals: We present in this paper a detailed analysis of the flexoelectric instability\nof a planar nematic layer in the presence of an alternating electric field\n(frequency $\\omega$), which leads to stripe patterns (flexodomains) in the\nplane of the layer. This equilibrium transition is governed by the free energy\nof the nematic which describes the elasticity with respects to the\norientational degrees of freedom supplemented by an electric part. Surprisingly\nthe limit $\\omega \\to 0$ is highly singular. In distinct contrast to the\ndc-case, where the patterns are stationary and time-independent, they appear at\nfinite, small $\\omega$ periodically in time as sudden bursts. Flexodomains are\nin competition with the intensively studied electro-hydrodynamic instability in\nnematics, which presents a non-equilibrium dissipative transition. It will be\ndemonstrated that $\\omega$ is a very convenient control parameter to tune\nbetween flexodomains and convection patterns, which are clearly distinguished\nby the orientation of their stripes."
    },
    {
        "anchor": "Entropically Patchy Particles: Engineering Valence through Shape Entropy: Patchy particles are a popular paradigm for the design and synthesis of\nnanoparticles and colloids for self-assembly. In \"traditional\" patchy\nparticles, anisotropic interactions arising from patterned coatings,\nfunctionalized molecules, DNA, and other enthalpic means create the possibility\nfor directional binding of particles into higher-ordered structures. Although\nthe anisotropic geometry of non-spherical particles contributes to the\ninteraction patchiness through van der Waals, electrostatic, and other\ninteractions, how particle shape contributes entropically to self-assembly is\nonly now beginning to be understood. It has been recently demonstrated that,\nfor hard shapes, entropic forces are directional. A newly proposed theoretical\nframework that defines and quantifies directional entropic forces demonstrates\nthe anisotropic--that is, patchy--nature of these emergent, attractive forces.\nHere we introduce the notion of entropically patchy particles as the entropic\ncounterpart to enthalpically patchy particles. Using three example \"families\"\nof shapes, we judiciously modify entropic patchiness by introducing geometric\nfeatures to the particles so as to target specific crystal structures, which\nthen assembled with Monte Carlo simulations. We quantify the emergent entropic\nvalence via a potential of mean force and torque. We generalize these shape\noperations to shape anisotropy dimensions, in analogy with the anisotropy\ndimensions introduced for enthalpically patchy particles. Our findings\ndemonstrate that entropic patchiness and emergent valence provide a way of\nengineering directional bonding into nanoparticle systems, whether in the\npresence or absence of additional, non-entropic forces.",
        "positive": "Topological changes at the jamming and gel transition of a reversible\n  polymeric network: We investigate the network topologies of an ensemble of telechelic polymers.\nThe telechelic polymers serve as links between nodes, which consist of\naggregates of their telechelic endgroups. Our analysis shows that the degree\ndistribution is bimodal and consists of two Poissonian distributions with\ndifferent average degrees. The number of nodes in each of them as well as the\ndistribution of links depends on temperature. By comparing the eigenvalue\nspectra of the simulated network gels with those of reconstructed networks, the\nmost likely ttopology at each temperature is determined."
    },
    {
        "anchor": "Flocking without alignment interactions in attractive active Brownian\n  particles: Within a simple model of attractive active Brownian particles, we predict\nflocking behavior and challenge the widespread idea that alignment interactions\nare necessary to observe this collective phenomenon. Here, we show that even\nnon-aligning attractive interactions can lead to a flocking state. Monitoring\nthe velocity polarization as the order parameter, we reveal the onset of a\nfirst-order transition from a disordered phase, characterized by several small\nclusters, to a flocking phase, where a single flocking cluster is emerging. The\nscenario is confirmed by studying the spatial connected correlation function of\nparticle velocities, which reveals scale-free behavior in flocking states and\nexponential-like decay for non-flocking configurations. Our predictions can be\ntested in microscopic and macroscopic experiments showing flocking, such as\nanimals, migrating cells, and active colloids.",
        "positive": "Boundary layer coupling of solid particles in water in an ultrasonic\n  field: In an ultrasonic field the region around a solid particle experiences small,\nlocalised velocity, pressure, and thermal fluctuations that decay rapidly over\nshort length scales. Herein, we investigate the overlap of the rapidly decaying\nfields between two silica particles in water in the case where the particles\nare aligned with each other in the direction of the applied field. We explore\nthe velocity, pressure, temperature, and vorticity in the region of the\nparticles. We discuss the coupled particle effects in ultrasonic waves as\nparticles begin to agglomerate or become more concentrated. The analysis is\nconducted in the long wavelength regime for particles of diameter 500 nm and\nfrequency 9.7 MHz."
    },
    {
        "anchor": "Electrostatic theory of the acidity of the solution in the lumina of\n  viruses and virus-like particles: Recently, Maassen et al. measured an appreciable pH difference between the\nbulk solution and the solution in the lumen of virus-like particles,\nself-assembled in an aqueous buffer solution containing the coat proteins of a\nsimple plant virus and polyanions. [Maassen, S. J.; et al. Small 2018, 14,\n1802081] They attribute this to the Donnan effect, caused by an imbalance\nbetween the number of negative charges on the encapsulated polyelectrolyte\nmolecules and the number of positive charges on the RNA binding domains of the\ncoat proteins that make up the virus shell or capsid. By applying\nPoisson-Boltzmann theory, we confirm this conclusion and show that simple\nDonnan theory is accurate even for the smallest of viruses and virus-like\nparticles. This, in part, is due to the additional screening caused by the\npresence of a large number of immobile charges in the cavity of the shell. The\npresence of a net charge on the outer surface of the capsid we find in practice\nto not have a large effect on the pH shift. Hence, Donnan theory can indeed be\napplied to connect the local pH and the amount of encapsulated material. The\nlarge shifts up to a full pH unit that we predict must have consequences for\napplications of virus capsids as nanocontainers in bionanotechnology and\nartificial cell organelles.",
        "positive": "Colloidal motility and pattern formation under rectified\n  diffusiophoresis: In this letter, we characterize experimentally the diffusiophoretic motion of\ncolloids and lambda- DNA toward higher concentration of solutes, using\nmicrofluidic technology to build spatially- and temporally-controlled\nconcentration gradients. We then demonstrate that segregation and spatial\npatterning of the particles can be achieved from temporal variations of the\nsolute concentration profile. This segregation takes the form of a strong\ntrapping potential, stemming from an osmotically induced rectification\nmechanism of the solute time-dependent variations. Depending on the spatial and\ntemporal symmetry of the solute signal, localization patterns with various\nshapes can be achieved. These results highlight the role of solute contrasts in\nout-of-equilibrium processes occuring in soft matter."
    },
    {
        "anchor": "Compact Layer of Alkali Ions at the Surface of Colloidal Silica: The forces of electrical imaging strongly polarize the surface of colloidal\nsilica. I used X-ray scattering to study the adsorbed 2-nm-thick compact layer\nof alkali ions at the surface of concentrated solutions of 5-nm, 7-nm, and\n22-nm particles, stabilized either by NaOH or a mixture of NaOH and CsOH, with\nthe total bulk concentration of alkali ions ranging from 0.1- to 0.7-mol/L. The\nobserved structure of the compact layer is almost independent of the size of\nthe particles and concentration of alkali base in the sol; it can be described\nby a two-layer model, i.e., an ~ 8 Angstrom thick layer of directly adsorbed\nhydrated alkali ions with a surface concentration 3x10(18) m(-2), and a ~ 13\nAngstrom thick layer with a surface concentration of sodium ions 8x10(18)\nm(-2). In cesium-enriched sols, Cs+ ions preferentially adsorb in the first\nlayer replacing Na+; their density in the second layer does not depend on the\npresence of cesium in the sol. The difference in the adsorption of Cs+ and Na+\nions can be explained by the ion-size-dependent term in the electrostatic Gibbs\nenergy equation derived earlier by others. I also discuss the surface charge\ndensity and the value of surface tension at the sol's surface.",
        "positive": "A nonlinear theory of non-stationary low Mach number channel flows of\n  freely cooling nearly elastic granular gases: We use hydrodynamics to investigate non-stationary channel flows of freely\ncooling dilute granular gases. We focus on the regime where the sound travel\ntime through the channel is much shorter than the characteristic cooling time\nof the gas. As a result, the gas pressure rapidly becomes almost homogeneous,\nwhile the typical Mach number of the flow drops well below unity. Eliminating\nthe acoustic modes, we reduce the hydrodynamic equations to a single nonlinear\nand nonlocal equation of a reaction-diffusion type in Lagrangian coordinates.\nThis equation describes a broad class of channel flows and, in particular, can\nfollow the development of the clustering instability from a weakly perturbed\nhomogeneous cooling state to strongly nonlinear states. If the heat diffusion\nis neglected, the reduced equation is exactly soluble, and the solution\ndevelops a finite-time density blowup. The heat diffusion, however, becomes\nimportant near the attempted singularity. It arrests the density blowup and\nbrings about novel inhomogeneous cooling states (ICSs) of the gas, where the\npressure continues to decay with time, while the density profile becomes\ntime-independent. Both the density profile of an ICS, and the characteristic\nrelaxation time towards it are determined by a single dimensionless parameter\nthat describes the relative role of the inelastic energy loss and heat\ndiffusion. At large values of this parameter, the intermediate cooling dynamics\nproceeds as a competition between low-density regions of the gas. This\ncompetition resembles Ostwald ripening: only one hole survives at the end."
    },
    {
        "anchor": "Photoactivated Colloidal Dockers for Cargo Transportation: We introduce a self-propelled colloidal hematite docker that can be steered\nto a small particle cargo many times its size, dock, transport the cargo to a\nremote location, and then release it. The self-propulsion and docking are\nreversible and activated by visible light. The docker can be steered either by\na weak uniform magnetic field or by nanoscale tracks in a textured substrate.\nThe light-activated motion and docking originate from osmotic/phoretic particle\ntransport in a concentration gradient of fuel, hydrogen peroxide, induced by\nthe photocatalytic activity of the hematite. The docking mechanism is versatile\nand can be applied to various materials and shapes. The hematite dockers are\nsimple single-component particles and are synthesized in bulk quantities. This\nsystem opens up new possibilities for designing complex micrometer-size\nfactories as well as new biomimetic systems.",
        "positive": "Effects of electromagnetic waves on the electrical properties of\n  contacts between grains: A DC electrical current is injected through a chain of metallic beads. The\nelectrical resistances of each bead-bead contacts are measured. At low current,\nthe distribution of these resistances is large and log-normal. At high enough\ncurrent, the resistance distribution becomes sharp and Gaussian due to the\ncreation of microweldings between some beads. The action of nearby\nelectromagnetic waves (sparks) on the electrical conductivity of the chain is\nalso studied. The spark effect is to lower the resistance values of the more\nresistive contacts, the best conductive ones remaining unaffected by the spark\nproduction. The spark is able to induce through the chain a current enough to\ncreate microweldings between some beads. This explains why the electrical\nresistance of a granular medium is so sensitive to the electromagnetic waves\nproduced in its vicinity."
    },
    {
        "anchor": "Lift induced by slip inhomogeneities in lubricated contacts: Lubrication forces depend to a high degree on elasticity, texture, charge,\nchemistry, and temperature of the interacting surfaces. Therefore, by\nappropriately designing surface properties, we may tailor lubrication forces to\nreduce friction, adhesion and wear between sliding surfaces or control\nrepulsion, assembly, and collision of interacting particles. Here, we show that\nvariations of slippage on one of the contacting surfaces induce a lift force.\nWe demonstrate the consequences of this force on the mobility of a cylinder\ntraveling near a wall and show the emergence of particle oscillation and\nmigration that would not otherwise occur in the Stokes flow regime.Our study\nhas implications for understanding how inhomogeneous biological interfaces\ninteract with their environment; it also reveals a new method of patterning\nsurfaces for controlling the motion of nearby particles.",
        "positive": "Non-affinity and fluid-coupled viscoelastic plateau for immersed fiber\n  networks: We employ a matrix-based solver for the linear rheology of fluid-immersed\ndisordered spring networks to reveal four distinct dynamic response regimes.\nOne regime - completely absent in the known vacuum response - exhibits coupled\nfluid flow and network deformation, with both components responding\nnon-affinely. This regime contains an additional plateau (peak) in the\nfrequency-dependent storage (loss) modulus - features which vanish without full\nhydrodynamic interactions. The mechanical response of immersed networks such as\nbiopolymers and hydrogels is thus richer than previously established, and\noffers additional modalities for design and control through fluid interactions."
    },
    {
        "anchor": "Equilibrium morphologies and force extension behavior for polymers with\n  hydrophobic patches: Role of quenched disorder: Motivated by single molecule experiments on biopolymers we explore\nequilibrium morphologies and force-extension behavior of copolymers with\nhydrophobic segments using Langevin dynamics simulations. We find that the\ninterplay between different length scales, namely, the persistence length\n$\\ell_{p}$, and the disorder correlation length $p$, in addition to the\nfraction of hydrophobic patches $f$ play a major role in altering the\nequilibrium morphologies and mechanical response. In particular, we show a\nplethora of equilibrium morphologies for this system, \\textit{e.g.} core-shell,\nlooped (with hybridised hydrophilic-hydrophobic sections), and extended coils\nas a function of these parameters. A competition of bending energy and\nhybridisation energies between two types of beads determines the equilibrium\nmorphology. Further, mechanical properties of such polymer architectures are\ncrucially dependent on their native conformations, and in turn on the disorder\nrealisation along the chain backbone. Thus, for flexible chains, a globule to\nextended coil transition is effected via a tensile force for all disorder\nrealisations. However, the exact nature of the force-extension curves are\ndifferent for the different disorder realisations. In contrast, we find that\nforce-extension behavior of semi-flexible chains with different equilibrium\nconfigurations \\textit{e.g.} core-shell, looped, \\textit{etc.} reveal a cascade\nof force-induced conformational transitions.",
        "positive": "Viscoelastic control of spatiotemporal order in bacterial active matter: Active matter consists of units that generate mechanical work by consuming\nenergy. Examples include living systems, such as assemblies of bacteria and\nbiological tissues, biopolymers driven by molecular motors, and suspensions of\nsynthetic self-propelled particles. A central question in the field is to\nunderstand and control the self-organization of active assemblies in space and\ntime. Most active systems exhibit either spatial order mediated by interactions\nthat coordinate the spatial structure and the motion of active agents or the\ntemporal synchronization of individual oscillatory dynamics. The simultaneous\ncontrol of spatial and temporal organization is more challenging and generally\nrequires complex interactions, such as reaction-diffusion hierarchies or\ngenetically engineered cellular circuits. Here, we report a novel and simple\nmeans to simultaneously control the spatial and temporal self-organization of\nbacterial active matter. By confining an active bacterial suspension and\nmanipulating a single macroscopic parameter, namely the viscoelasticity of the\nsuspending fluid, we have found that the bacterial fluid first self-organizes\nin space into a millimeter-scale rotating vortex; then displays temporal\norganization as the giant vortex switches its global chirality periodically\nwith tunable frequency, reminiscent of a torsional pendulum - a self-driven\none. Combining experiments with an active matter model, we explain this\nstriking behavior in terms of the interplay between active forcing and\nviscoelastic stress relaxation. Our findings advance the understanding of\nbacterial behavior in complex fluids, and demonstrate experimentally for the\nfirst time that rheological properties can be harnessed to control active\nmatter flows. Coupled with actuation, our tunable self-oscillating bacterial\nvortex may be used as a \"clock\" for locomotion of soft robots and microfluidic\npumping."
    },
    {
        "anchor": "Flagellated bacterial motility in polymer solutions: It is widely believed that the swimming speed, $v$, of many flagellated\nbacteria is a non-monotonic function of the concentration, $c$, of\nhigh-molecular-weight linear polymers in aqueous solution, showing peaked\n$v(c)$ curves. Pores in the polymer solution were suggested as the explanation.\nQuantifying this picture led to a theory that predicted peaked $v(c)$ curves.\nUsing new, high-throughput methods for characterising motility, we have\nmeasured $v$, and the angular frequency of cell-body rotation, $\\Omega$, of\nmotile Escherichia coli as a function of polymer concentration in\npolyvinylpyrrolidone (PVP) and Ficoll solutions of different molecular weights.\nWe find that non-monotonic $v(c)$ curves are typically due to low-molecular\nweight impurities. After purification by dialysis, the measured $v(c)$ and\n$\\Omega(c)$ relations for all but the highest molecular weight PVP can be\ndescribed in detail by Newtonian hydrodynamics. There is clear evidence for\nnon-Newtonian effects in the highest molecular weight PVP solution.\nCalculations suggest that this is due to the fast-rotating flagella `seeing' a\nlower viscosity than the cell body, so that flagella can be seen as\nnano-rheometers for probing the non-Newtonian behavior of high polymer\nsolutions on a molecular scale.",
        "positive": "Salt-induced collapse and reexpansion of highly charged flexible\n  polyelectrolytes: We study the salt-dependent conformations of dilute flexible polyelectrolytes\nin solution via computer simulations. Low concentrations of multivalent salt\ninduce the known conformational collapse of individual polyelectrolyte chains,\nbut as the salt concentration is increased further this is followed by a\nreexpansion. We explicitly demonstrate that multivalent counterions can\novercompensate the bare charge of the chain in the reexpansion regime. Both the\ndegree of reexpansion and the occurrence of overcharging sensitively depend on\nion size. Our findings are relevant for a wide range of salt-induced\ncomplexation phenomena."
    },
    {
        "anchor": "Simplification of protein representation from the contact potentials\n  between residues: Based on the concept of energy landscape a picture of the mismatch between\nthe reduced interaction matrix of residues and the matrix of statistical\ncontact potentials is presented. For the Miyazawa and Jernigan (MJ) matrix,\nrational groupings of 20 kinds of residues with minimal mismatches under the\nconsideration of local minima and statistics on correlation between the\nresidues are studied. A hierarchical tree of groupings relating to different\nnumbers of groups $N$ is obtained, and a plateau around $N=8\\sim 10$ is found,\nwhich may represent the basic degree of freedom of the sequence complexity of\nproteins.",
        "positive": "Local analysis of the history dependence in tetrahedra packings: The mechanical properties of a granular sample depend frequently on the way\nthe packing was prepared. However, is not well understood which properties of\nthe packing store this information. Here we present an X-ray tomography study\nof three pairs of tetrahedra packings prepared with three different tapping\nprotocols. The packings in each pair differs in the number of mechanical\nconstraints $C$ imposed on the particles by their contacts, while their bulk\nvolume fraction $\\phi_{global}$ is approximately the same. We decompose $C$\ninto the contributions of the three different contact types possible between\ntetrahedra -- face-to-face (F2F), edge-to-face (E2F), and point contacts --\nwhich each fix a different amount of constraints. We then perform a local\nanalysis of the contact distribution by grouping the particles together\naccording to their individual volume fraction $\\phi_{local}$ computed from a\nVoronoi tessellation. We find that in samples which have been tapped\nsufficiently long the number of F2F contacts becomes an universal function of\n$\\phi_{local}$. In contrast the number of E2F and point contacts varies with\nthe applied tapping protocol. Moreover, we find that the anisotropy of the\nshape of the Voronoi cells depends on the tapping protocol. This behavior\ndiffers from spheres and ellipsoids and posses a significant constraint for any\nmean-field approach to tetrahedra packings."
    },
    {
        "anchor": "Stabilizing stick-slip friction: Even the most regular stick-slip frictional sliding is always stochastic,\nwith irregularity in both the intervals between slip events and the sizes of\nthe associated stress drops. Applying small-amplitude oscillations to the shear\nforce, we show, experimentally and theoretically, that the stick-slip periods\nsynchronize. We further show that this phase-locking is related to the\ninhibition of slow rupture modes which forces a transition to fast rupture,\nproviding a possible mechanism for observed remote triggering of earthquakes.\nSuch manipulation of collective modes may be generally relevant to extended\nnonlinear systems driven near to criticality.",
        "positive": "Protein folding mediated by solvation: water expelling and formation of\n  the hydrophobic core occurs after the structure collapse: The interplay between structure-search of the native structure and\ndesolvation in protein folding has been explored using a minimalist model.\nThese results support a folding mechanism where most of the structural\nformation of the protein is achieved before water is expelled from the\nhydrophobic core. This view integrates water expulsion effects into the funnel\nenergy landscape theory of protein folding. Comparisons to experimental results\nare shown for the SH3 protein. After the folding transition, a near-native\nintermediate with partially solvated hydrophobic core is found. This transition\nis followed by a final step that cooperatively squeezes out water molecules\nfrom the partially hydrated protein core."
    },
    {
        "anchor": "Solitons in Poly(oxyethylene): We introduce a soliton model to describe conformational structure of\npoly(oxyethylene) in aqueous solution. The model is based on former\ninvestigations for twistons in polyethylene, and the soliton solution\ncorresponds to stable excitation that locally transforms the gauche\nconformation of the O-CH2-CH2-O dihedral angle from the positive (negative)\nconfiguration to its negative (positive) partner. The conformational\ndeformation in the polymer main chain is mediated by the unstable cis\nconformation which changes the physical profile of the chain, contributing to\ntrigger important properties of the polymer. For instance, it may activate the\nprocess for the capture of metallic ions in aqueous solution and it may also\nenlarge solubility of the polymer in water. The soliton solution is used to\nguide a quantum chemistry investigation that examine, and characterize, a chain\ncontaining 40 monomeric units, tracing quantitative correlations with the\nsoliton model.",
        "positive": "Shear-thinning in dense colloidal suspensions and its effect on elastic\n  instabilities: from the microscopic equations of motion to an approximation\n  of the macroscopic rheology: In the vicinity of their glass transition, dense colloidal suspensions\nacquire elastic properties over experimental timescales. We investigate the\npossibility of a visco-elastic flow instability in curved geometry for such\nmaterials. To this end, we first present a general strategy extending a\nfirst-principles approach based on projections onto slow variables (so far\nrestricted to strictly homogeneous flow) in order to handle inhomogeneities. In\nparticular, we separate the advection of the microstructure by the flow, at the\norigin of a fluctuation advection term, from the intrinsic dynamics. On account\nof the complexity of the involved equations, we then opt for a drastic\nsimplification of the theory, in order to establish its potential to describe\ninstabilities. These very strong approximations lead to a constitutive equation\nof the White-Metzner class, whose parameters are fitted with experimental\nmeasurements of the macroscopic rheology of a glass-forming colloidal\ndispersion. The model properly accounts for the shear-thinning properties of\nthe dispersions, but, owing to the approximations, the description is not fully\nquantitative. Finally, we perform a linear stability analysis of the flow in\nthe experimentally relevant cylindrical (Taylor-Couette) geometry and provide\nevidence that shear-thinning strongly stabilises the flow, which can explain\nwhy visco-elastic instabilities are not observed in dense colloidal\nsuspensions."
    },
    {
        "anchor": "Crystalline Order on Catenoidal Capillary Bridges: We study the defect structure of crystalline particle arrays on negative\nGaussian curvature capillary bridges with vanishing mean curvature (catenoids).\nThe threshold aspect ratio for the appearance of isolated disclinations is\nfound and the optimal positions for dislocations determined. We also discuss\nthe transition from isolated disclinations to scars as particle number and\naspect ratio are varied.",
        "positive": "Hysteresis of bond-orientational order in 2D overdamped Yukawa systems: This paper has been withdrawn by the author due to need for more improvement."
    },
    {
        "anchor": "Morphometric description of strength and degradation in porous media: The influence of the microstructural geometry on the behavior of porous media\nis widely recognized, particularly in geomaterials, but also in biomaterials\nand engineered materials. Recent advances in imaging techniques, such as X-ray\nmicrocomputed tomography, and in modeling make it possible to capture the exact\nmorphometry of the microstructure with high precision. However, most existing\ncontinuum theories only partially account for the morphometry. We propose here\na unifying approach to link the strength of porous materials with the necessary\nand sufficient microstructural information, using Minkowski functionals, as per\nHadwiger's theorem. A morphometric strength law is inferred from synthetic\nmicrostructures with a wide range of porosities and heterogeneities, through\nqualitative 2D phase-field simulations. Namely, the damage is modeled at the\nmicrostructural level by tracking the solid-pore interfaces under mechanical\nloading. The strength is found to be best described by an exponential function\nof the morphometers, thus generalizing early works on metals and ceramics. We\nthen show that the predictiveness of this relationship extends to real porous\nmedia, including rocks and bones.",
        "positive": "Dynamic Landau Theory for Supramolecular Self-Assembly: Although pathway-specific kinetic theories are fundamentally important to\ndescribe and under- stand reversible polymerisation kinetics, they come in\nprinciple at a cost of having a large number of system-specific parameters.\nHere, we construct a dynamical Landau theory to describe the kinetics of\nactivated linear supramolecular self-assembly, which drastically reduces the\nnumber of parameters and still describes most of the interesting and generic\nbehavior of the system in hand. This phenomenological approach hinges on the\nfact that if nucleated, the polymerisation transition resembles a phase\ntransition. We are able to describe hysteresis, overshooting, undershooting and\nthe existence of a lag time before polymerisation takes o?, and pinpoint the\nconditions required for observing these types of phenomenon in the assembly and\ndisassembly kinetics. We argue that the phenomenological kinetic parameter in\nour theory is a pathway controller, i.e., it controls the relative weights of\nthe molecular pathways through which self-assembly takes place."
    },
    {
        "anchor": "Free Energy Landscape of Protein-like Chains with Discontinuous\n  Potentials: In this article the configurational space of two simple protein models\nconsisting of polymers composed of a periodic sequence of four different kinds\nof monomers is studied as a function of temperature. In the protein models,\nhydrogen bond interactions, electrostatic repulsion, and covalent bond\nvibrations are modeled by discontinuous step, shoulder and square-well\npotentials, respectively. The protein-like chains exhibit a secondary alpha\nhelix structure in their folded states at low temperatures, and allow a natural\ndefinition of a configuration by considering which beads are bonded. Free\nenergies and entropies of configurations are computed using the parallel\ntempering method in combination with hybrid Monte Carlo sampling of the\ncanonical ensemble of the discontinuous potential system. The probability of\nobserving the most common configuration is used to analyze the nature of the\nfree energy landscape, and it is found that the model with the least number of\npossible bonds exhibits a funnel-like free energy landscape at low enough\ntemperature for chains with fewer than 30 beads. For longer proteins, the\nlandscape consists of several minima, where the configuration with the lowest\nfree energy changes significantly by lowering the temperature and the\nprobability of observing the most common configuration never approaches one due\nto the degeneracy of the lowest accessible potential energy.",
        "positive": "Force-Extension for DNA in a Nanoslit: Using an Effective Dimensionality\n  to Map between the 3D and 2D Limits: The force-extension relation for a semi-flexible polymer such as DNA confined\nin a nanoslit is investigated and it is found that both the effective\npersistence length and the form of the force-extension relation change as the\nchain goes from 3D (very large slit heights) to 2D (very tight confinement).\nGeneralizations of the Marko-Siggia relation appropriate for polymers in\nnanoconfinement are presented. The forms for both strong and weak confinement\nregimes are characterized by an \\textit{effective dimensionality}. At low\nforces, the effective dimensionality is given by the correlations along the\npolymer in the plane of the confining walls. At high forces, the theoretical\nforce must account for reduced conformation space. Together the interpolations\ngive good agreement for all slit heights at all forces. As DNA and other\nsemi-flexible biopolymers are commonly confined \\textit{in situ} to various\ndegrees, both the idea of an effective dimensionality and the associated\ngeneralized Marko-Siggia interpolations are useful for qualitatively\nunderstanding and quantitatively modeling polymers in nanoconfinement."
    },
    {
        "anchor": "STM Studies of Synthetic Peptide Monolayers: We have used scanning probe microscopy to investigate self-assembled\nmonolayers of chemically synthesized peptides. We find that the peptides form a\ndense uniform monolayer, above which is found a sparse additional layer. Using\nscanning tunneling microscopy, submolecular resolution can be obtained,\nrevealing the alpha helices which constitute the peptide. The nature of the\nimages is not significantly affected by the incorporation of redox cofactors\n(hemes) in the peptides.",
        "positive": "Transients in sheared granular matter: As dense granular materials are sheared, a shear band and an anisotropic\nforce network form. The approach to steady state behavior depends on the\nhistory of the packing and the existing force and contact network. We present\nexperiments on shearing of dense granular matter in a 2D Couette geometry in\nwhich we probe the history and evolution of shear bands by measuring particle\ntrajectories and stresses during transients. We find that when shearing is\nstopped and restarted in the same direction, steady state behavior is\nimmediately reached, in agreement with the typical assumption that the system\nis quasistatic. Although some relaxation of the force network is observed when\nshearing is stopped, quasistatic behavior is maintained because the contact\nnetwork remains essentially unchanged. When the direction of shear is reversed,\na transient occurs in which stresses initially decrease, changes in the force\nnetwork reach further into the bulk, and particles far from the wheel become\nmore mobile. This occurs because the force network is fragile to changes\ntransverse to the force network established under previous shear; particles\nmust rearrange before becoming jammed again, thereby providing resistance to\nshear in the reversed direction. The strong force network is reestablished\nafter displacing the shearing surface $\\approx 3d$, where $d$ is the mean grain\ndiameter. Steady state velocity profiles are reached after a shear of $\\leq\n30d$. Particles immediately outside of the shear band move on average less than\n1 diameter before becoming jammed again. We also examine particle rotation\nduring this transient and find that mean particle spin decreases during the\ntransient, which is related to the fact that grains are not interlocked as\nstrongly."
    },
    {
        "anchor": "Finite Size Polyelectrolyte Bundles at Thermodynamic Equilibrium: We present the results of extensive computer simulations performed on\nsolutions of monodisperse charged rod-like polyelectrolytes in the presence of\ntrivalent counterions. To overcome energy barriers we used a combination of\nparallel tempering and hybrid Monte Carlo techniques. Our results show that for\nsmall values of the electrostatic interaction the solution mostly consists of\ndispersed single rods. The potential of mean force between the polyelectrolyte\nmonomers yields an attractive interaction at short distances. For a range of\nlarger values of the Bjerrum length, we find finite size polyelectrolyte\nbundles at thermodynamic equilibrium. Further increase of the Bjerrum length\neventually leads to phase separation and precipitation. We discuss the origin\nof the observed thermodynamic stability of the finite size aggregates.",
        "positive": "Elastic Wave Propagation and Bandgaps in Finitely Stretched Soft Lattice\n  Material: In this study, the in-plane Bloch wave propagation and bandgaps in a finitely\nstretched square lattice were investigated numerically and theoretically. To be\nspecific, the elastic band diagram was calculated for an infinite periodic\nstructure with a cruciform hyperelastic unit cell under uniaxial or biaxial\ntension. In addition, an elastodynamic \"tight binding\" model was proposed to\ninvestigate the formation and evolution of the band structure. The elastic\nwaves were found to propagate largely under \"easy\" modes in the pre-stretched\nsoft lattice, and finite stretch tuned the symmetry of the band structure, but\nalso \"purify\" the propagation modes. Moreover, the uniaxial stretch exhibits\nthe opposite impacts on the two \"easy\" modes. The effect of the biaxial stretch\nwas equated with the superposition of the uniaxial stretches in the\ntessellation directions. The mentioned effects on the band structure could be\nattributed to the competition between the effective shear moduli and lengths\nfor different beam components. Next, the finite stretch could tune the\ndirectional bandgap of the soft lattice, and the broadest elastic wave bandgaps\ncould be anticipated in an equi-biaxial stretch. In this study, an avenue was\nopened to design and implement elastic wave control devices with weight\nefficiency and tunability. Furthermore, the differences between the physical\nsystem and the corresponding simplified theoretical model (e.g., the\ntheoretically predicted flat bands) did not exist in the numerical\ncalculations."
    },
    {
        "anchor": "Decorated Protein Networks: Functional Nanomaterials with Tunable Domain\n  Size: The implementation of natural and artificial proteins with designer\nproperties and functionalities offers unparalleled opportunity for functional\nnanoarchitectures formed through self-assembly. However, to exploit the\nopportunities offered we require the ability to control protein assembly into\nthe desired architecture while avoiding denaturation and therefore retaining\nprotein functionality. Here we address this challenge with a model system of\nfluorescent proteins. Using techniques of self-assembly manipulation inspired\nby soft matter where interactions between components are controlled to yield\nthe desired structure, we show that it is possible to assemble networks of\nproteins of one species which we can decorate with another, whose coverage we\ncan tune. Consequently, the interfaces between domains of each component can\nalso be tuned, with applications for example in energy transfer. Our model\nsystem of fluorescent proteins eGFP and mCherry retain their fluorescence\nthroughout the assembly process, thus demonstrating that functionality is\npreserved.",
        "positive": "The excluded area of two-dimensional hard particles: The excluded area between a pair of two-dimensional hard particles with given\nrelative orientation is the region in which one particle cannot be located due\nto the presence of the other particle. The magnitude of the excluded area as a\nfunction of the relative particle orientation plays a major role in the\ndetermination of the bulk phase behaviour of hard particles. We use principal\ncomponent analysis to identify the different types of excluded area\ncorresponding to randomly generated two-dimensional hard particles modeled as\nnon-self-intersecting polygons and star lines (line segments radiating from a\ncommon origin). Only three principal components are required to have an\nexcellent representation of the value of the excluded area as a function of the\nrelative particle orientation. Independently of the particle shape, the minimum\nvalue of the excluded area is always achieved when the particles are\nantiparallel to each other. The property that affects the value of the excluded\narea most strongly is the elongation of the particle shape. Principal component\nanalysis identifies four limiting cases of excluded areas with one to four\nglobal minima at equispaced relative orientations. We study selected particle\nshapes using Monte Carlo simulations."
    },
    {
        "anchor": "Smectite phase separation is driven by emergent interfacial dynamics: Smectite clay minerals have an outsize impact on the response of clay-rich\nmedia to common stimuli, such as water imbibition and ion exchange, motivating\nextensive effort to understand microscopic behaviors resulting from these\nprocesses such as swelling and exfoliation. Nonetheless, there is no general\nconsensus about the microscopic forces that govern smectite properties, which\nare model systems for understanding colloidal and interfacial phenomena more\ngenerally. We find that the complex free energy surface arising from the\ninterplay of at least four intermolecular forces and their nonlinear couplings\nthat control local particle-particle interactions leads to dynamic, unstable\nequilibria between distinct phases. Mechanical disequilibrium arising from\nosmotic gradients between curved or interacting interfaces drive the dynamic\nexchange of layers and ions between dense and dilute phases via avalanche\ntransitions that are sustained by thermal fluctuations. We suggest that the\nsurprising interfacial dynamics displayed by smectite minerals, arising from\nthe vastly different mobilities of water, ions and mineral, makes them\nfundamentally distinct from non-clay minerals because their structures are\neasily perturbed away from simultaneous chemical and mechanical equilibrium.",
        "positive": "Impact of Local Stiffness on Entropy Driven Microscopic Dynamics of\n  Polythiophene: We exploited the high temporal and spatial resolution of neutron spin echo\nspectroscopy to investigate the large-scale dynamics of semiflexible conjugated\npolymer chains in solutions. We obtained the first experimental demonstration\nof earlier predicted single chain glassy state. We used a generalized approach\nof the well-established Zimm model of flexible polymers to describe the\nrelaxation mode spectra of locally stiff polythiophene chains. The Zimm mode\nanalysis confirms the existence of beads with a finite length that corresponds\nto a reduced number of segmental modes in semiflexible chains. Irrespective of\nthe temperature and the molecular weight of the conjugated polymer, we witness\na universal behavior of the local chain stiffness and invariability of the\nbeads length. Our experimental findings indicate possibly minor role of the\nchange in {\\pi}-electron conjugation length (and therefore conjugated backbone\nplanar to non-planar conformational transition) in the observed thermochromic\nbehavior of polythiophene but instead point on the major role of chain dynamics\nin this phenomenon."
    },
    {
        "anchor": "Mechanism of silica-lysozyme composite formation unravelled by in situ\n  fast SAXS: A quantitative understanding of aggregation mechanisms leading to the\nformation of inorganic nanoparticles (NPs) and protein composites in aqueous\nmedia is of paramount interest for colloid chemistry. In particular, the\ninteractions between silica (SiO2) NPs and lysozyme (LZM) have attracted\nattention, because LZM is well-known to adsorb strongly to silica NPs, while at\nthe same time preserving its enzymatic activity. The inherent nature of the\naggregation processes leading to NP-LZM composites involves structural changes\nat length-scales from few to hundreds of nanometres but also time scales << 1\nsecond. To unravel these we used in situ synchrotron-based small-angle X-ray\nscattering (SAXS) and followed the subtle interparticle interactions in\nsolution at a time resolution of 50 ms/frame (20 fps). We show that if the size\nof silica NPs (~5 nm diameter) is matched by the dimensions of LZM, the\nevolving scattering patterns contain a unique structure factor contribution\noriginating from the presence of LZM. We developed a scattering model and\napplied it to analyse this structure function, which allowed us to extract\nstructural information on the deformation of lysozyme molecules during\naggregation, as well as to derive the mechanisms of composite formation.",
        "positive": "Planar and curved droplet networks: We study how a two-dimensional square sheet of droplets evolves to the\npreferred triangular lattice. The rearrangement can be induced either by an\nimpurity seed for flat sheets or by curving the sheet. We analyze the\npropagation of transformation fronts and the spatial reordering subsequent to\nthe initial perturbation."
    },
    {
        "anchor": "Reshaping and Enzymatic Activity allow Viruses to move through the Mucus: Filamentous viruses like influenza and torovirus often display systematic\nbends and arcs of mysterious physical origin. We propose that such viruses\nundergo an instability from a cylindrically symmetric to a toroidally curved\nstate. This \"toro-elastic\" state emerges via a spontaneous symmetry breaking\nunder prestress, induced via short range spike protein interactions and\nmagnified by the filament's surface topography. Once surface stresses become\nsufficiently large, the filament buckles and the toroidal, curved state\nconstitutes a soft mode that can propagate through the filament's material\nframe around a \"mexican-hat\" potential. In the mucus of our airways, glycan\nchains are omnipresent that influenza's spike proteins can bind to and cut. We\nshow that when coupled to such a non-equilibrium chemical reaction, the curved\ntoro-elastic state can attain a spontaneous rotation for sufficiently strong\nenzymatic activity, leading to a whole body reshaping propulsion similar to --\nbut different from -- eukaryotic flagella and spirochetes.",
        "positive": "Sedimentation path theory for mass-polydisperse colloidal systems: Both polydispersity and the presence of a gravitational field are inherent to\nessentially any colloidal experiment. While several theoretical works have\nfocused on the effect of polydispersity on the bulk phase behavior of a\ncolloidal system, little is known about the effect of a gravitational field on\na polydisperse colloidal suspension. We extend here sedimentation path theory\nto study sedimentation-diffusion-equilibrium of a mass-polydisperse colloidal\nsystem: the particles possess different buoyant masses but they are otherwise\nidentical. The model helps to understand the interplay between gravity and\npolydispersity on sedimentation experiments. Since the theory can be applied to\nany parent distribution of buoyant masses, it can be also used to study\nsedimentation of monodisperse colloidal systems. We find that\nmass-polydispersity has a strong influence in colloidal systems near density\nmatching for which the bare density of the colloidal particles equals the\nsolvent density. To illustrate the theory, we study crystallization in\nsedimentation-diffusion-equilibrium of a suspension of mass-polydisperse hard\nspheres."
    },
    {
        "anchor": "Topological analysis and the recovery of entanglements in polymer melts: The viscous flow of polymer chains in dense melts is dominated by topological\nconstraints whenever the single chain contour length, N, becomes larger than\nthe characteristic scale Ne, defining comprehensively the macroscopic\nrheological properties of the highly entangled polymer systems. Even though the\nlatter are naturally connected to the presence of hard constraints like knots\nand links within the polymer chains, the difficulty of integrating the rigorous\nlanguage of mathematical topology with the physics of polymer melts has limited\nsomehow a genuine topological approach to the problem of classifying these\nconstraints and to how they are related to the rheological entanglements. In\nthis work, we tackle this problem by studying the occurrence of knots and links\nin lattice melts of randomly knotted and randomly concatenated ring polymers of\nvarious bending stiffness. Specifically, by introducing an algorithm which\nshrinks the chains to their minimal shapes which do not violate topological\nconstraints and by analyzing those in terms of suitable topological invariants,\nwe provide a detailed characterization of the topological properties at the\nintra-chain level (knots) and of links between pairs and triplets of distinct\nchains. Then, by employing the Z1-algorithm on the minimal conformations in\norder to extract the entanglement length $N_e$, we show that the ratio $N/N_e$,\nthe number of entanglements per chain, can be remarkably well reconstructed in\nterms of 2-chain links solely.",
        "positive": "Signal propagation through dense granular systems: The manner in which signals propagate through dense granular systems in both\nspace and time is not well understood. In order to learn more about this\nprocess, we carry out discrete element simulations of the system response to\nexcitations where we control the driving frequency and wavelength\nindependently. Fourier analysis shows that properties of the signal depend\nstrongly on the spatial and temporal scales introduced by the perturbation. The\nfeatures of the response provide a test-bed for any continuum theory attempting\nto predict signal properties. We illustrate this connection between micro-scale\nphysics and macro-scale behavior by comparing the system response to a simple\nelastic model with damping."
    },
    {
        "anchor": "Local Coulomb versus Global Failure Criterion for Granular Packings: Contacts at the Coulomb threshold are unstable to tangential perturbations\nand thus contribute to failure at the microscopic level. How is such a local\nproperty related to global failure, beyond the effective picture given by a\nMohr-Coulomb type failure criterion? Here, we use a simulated bed of frictional\ndisks slowly tilted under the action of gravity to investigate the link between\nthe avalanche process and a global generalized isostaticity criterion. The\navalanche starts when the packing as a whole is still stable according to this\ncriterion, underlining the role of large heterogeneities in the destabilizing\nprocess: the clusters of particles with fully mobilized contacts concentrate\nlocal failure. We demonstrate that these clusters, at odds with the pile as a\nwhole, are also globally marginal with respect to generalized isostaticity.\nMore precisely, we observe how the condition of their stability from a local\nmechanical proprety progressively builds up to the generalized isostaticity\ncriterion as they grow in size and eventually span the whole system when\napproaching the avalanche.",
        "positive": "Order and Frustration in Chiral Liquid Crystals: This paper reviews the complex ordered structures induced by chirality in\nliquid crystals. In general, chirality favors a twist in the orientation of\nliquid-crystal molecules. In some cases, as in the cholesteric phase, this\nfavored twist can be achieved without any defects. More often, the favored\ntwist competes with applied electric or magnetic fields or with geometric\nconstraints, leading to frustration. In response to this frustration, the\nsystem develops ordered structures with periodic arrays of defects. The\nsimplest example of such a structure is the lattice of domains and domain walls\nin a cholesteric phase under a magnetic field. More complex examples include\ndefect structures formed in two-dimensional films of chiral liquid crystals.\nThe same considerations of chirality and defects apply to three-dimensional\nstructures, such as the twist-grain-boundary and moire phases."
    },
    {
        "anchor": "Mechanical switching of ferro-electric rubber: At the A to C transition, smectic elastomers have recently been observed to\nundergo $\\sim$35% spontaneous shear strains. We first explicitly describe how\nstrains of up to twice this value could be mechanically or electrically induced\nin Sm-$C$ elastomers by rotation of the director on a cone around the layer\nnormal at various elastic costs depending on constraints. Secondly, for typical\nsample geometries, we give the various microstructures in Sm-$C$ akin to those\nseen in nematic elastomers under distortions with constraints. It is possible\nto give explicit results for the nature of the textures. Chiral Sm-$C$\nelastomers are ferro-electric. We calculate how the polarization could be\nmechanically reversed by large, hard or soft strains of the rubber, depending\nupon sample geometry.",
        "positive": "Phase field model of solid-liquid and liquid-liquid phase transitions in\n  flow and elastic fields in one-component systems: We construct a phase field model including hydrodynamics and elasticity in\none-component systems. It can be used to investigate solid-liquid and\nliquid-liquid phase transitions. Upon first-order phase transition, a velocity\nfield is induced around interfaces in the presence of a density difference\nbetween the two phases even without applied shear flow. As applications, we\npresent simulation results on two cases of melting, where a solid domain is\nplaced on a heated wall in one case and is suspended in a warmer liquid under\nshear flow in the other. We find that the solid domain moves or rotates as a\nwhole due to elasticity, releasing latent heat. We also examine the\nliquid-liquid phase transition of a highly viscous domain into a less viscous\nliquid on a heated wall, where an inhomogeneous velocity field is induced\nwithin a projected part of the domain. In these phase transitions, the\ninterface temperature is nearly equal to the coexisting temperature $T_{\\rm\ncx}(p)$ away from the heated wall in the presence of heat flow in the\nsurrounding liquid."
    },
    {
        "anchor": "Model for Dynamic Self-Assembled Magnetic Surface Structures: We propose a first-principles model for self-assembled magnetic surface\nstructures on the water-air interface reported in earlier experiments\n\\cite{snezhko2,snezhko4}. The model is based on the Navier-Stokes equation for\nliquids in shallow water approximation coupled to Newton equations for\ninteracting magnetic particles suspended on the water-air interface. The model\nreproduces most of the observed phenomenology, including spontaneous formation\nof magnetic snake-like structures, generation of large-scale vortex flows,\ncomplex ferromagnetic-antiferromagnetic ordering of the snake, and\nself-propulsion of bead-snake hybrids. The model provides valuable insights\ninto self-organization phenomena in a broad range of non-equilibrium magnetic\nand electrostatic systems with competing interactions.",
        "positive": "Nonlocal density functional theory of water taking into account\n  many-body dipole correlations: Binodal and surface tension of 'liquid-vapour'\n  interface: In this paper we formulate a nonlocal density functional theory of\ninhomogeneous water. We model a water molecule as a couple of oppositely\ncharged sites. The negatively charged sites interact with each other through\nthe Lennard-Jones potential (steric and dispersion interactions), square-well\npotential (short-range specific interactions due to electron charge transfer),\nand Coulomb potential, whereas the positively charged sites interact with all\ntypes of sites by applying the Coulomb potential only. Taking into account the\nnonlocal packing effects via the fundamental measure theory (FMT), dispersion\nand specific interactions in the mean-field approximation, and electrostatic\ninteractions at the many-body level through the random phase approximation, we\ndescribe the liquid-vapour interface. We demonstrate that our model without\nexplicit account of the association of water molecules due to hydrogen bonding\nand with explicit account of the many-body electrostatic interactions at the\nmany-body level is able to describe the liquid-vapour coexistence curve and the\nsurface tension at the ambient pressures and temperatures. We obtain very good\nagreement with available in the literature MD simulation results for density\nprofile of liquid-vapour interface at ambient state parameters. The formulated\ntheory can be used as a theoretical background for describing of the capillary\nphenomena, occurring in micro- and mesoporous materials."
    },
    {
        "anchor": "Gaussian Memory in Kinematic Matrix Theory for Self-Propellers: We extend the kinematic matrix (\"kinematrix\") formalism [Phys. Rev. E 89,\n062304 (2014)], which via simple matrix algebra accesses ensemble properties of\nself-propellers influenced by uncorrelated noise, to treat Gaussian correlated\nnoises. This extension brings into reach many real-world biological and\nbiomimetic self-propellers for which inertia is significant. Applying the\nformalism, we analyze in detail ensemble behaviors of a 2D self-propeller with\nvelocity fluctuations and orientation evolution driven by an Ornstein-Uhlenbeck\nprocess. On the basis of exact results, a variety of dynamical regimes\ndetermined by the inertial, speed-fluctuation, orientational diffusion, and\nemergent disorientation time scales are delineated and discussed.",
        "positive": "Wide shear zones and the spot model: Implications from the split-bottom\n  geometry: The spot model has been developed by Bazant and co-workers to describe\nquasistatic granular flows. It assumes that granular flow is caused by the\nopposing flow of so-called spots of excess free volume, with spots moving along\nthe slip lines of Mohr-Coulomb plasticity. The model is two-dimensional and has\nbeen successfully applied to a number of different geometries. In this paper we\ninvestigate whether the spot model in its simplest form can describe the wide\nshear zones observed in experiments and simulations of a Couette cell with\nsplit bottom. We give a general argument that is independent of the particular\ndescription of the stresses, but which shows that the present formulation of\nthe spot model in which diffusion and drift terms are postulated to balance on\nlength scales of order of the spot diameter, i.e. of order 3-5 grain diameters,\nis difficult to reconcile with the observed wide shear zones. We also discuss\nthe implications for the spot model of co-axiality of the stress and strain\nrate tensors found in these wide shear flows, and point to possible extensions\nof the model that might allow one to account for the existence of wide shear\nzones."
    },
    {
        "anchor": "The role of the roughness spectral breadth in elastic contact of rough\n  surfaces: We study frictionless and non-adhesive contact between elastic half-spaces\nwith self-affine surfaces. Using a recently suggested corrective technique, we\nensure an unprecedented accuracy in computation of the true contact area\nevolution under increasing pressure. This accuracy enables us to draw\nconclusions on the role of the surface's spectrum breadth (Nayak parameter) in\nthe contact area evolution. We show that for a given normalized pressure, the\ncontact area decreases logarithmically with the Nayak parameter. By linking the\nNayak parameter with the Hurst exponent (or fractal dimension), we show the\neffect of the latter on the true contact area. This effect, undetectable for\nsurfaces with poor spectral content, is quite strong for surfaces with rich\nspectra. Numerical results are compared with analytical models and other\navailable numerical results. A phenomenological equation for the contact area\ngrowth is suggested with coefficients depending on the Nayak parameter. Using\nthis equation, the pressure-dependent friction coefficient is deduced based on\nthe adhesive theory of friction. Some observations on Persson's model of rough\ncontact, whose prediction does not depend on Nayak parameter, are reported.\nOverall, the paper provides a unifying picture of rough elastic contact and\nclarifies discrepancies between preceding results.",
        "positive": "The Influence of the Degree of Heterogeneity on the Elastic Properties\n  of Random Sphere Packings: The macroscopic mechanical properties of colloidal particle gels strongly\ndepend on the local arrangement of the powder particles. Experiments have shown\nthat more heterogeneous microstructures exhibit up to one order of magnitude\nhigher elastic properties than their more homogeneous counterparts at equal\nvolume fraction. In this paper, packings of spherical particles are used as\nmodel structures to computationally investigate the elastic properties of\ncoagulated particle gels as a function of their degree of heterogeneity. The\ndiscrete element model comprises a linear elastic contact law, particle bonding\nand damping. The simulation parameters were calibrated using a homogeneous and\na heterogeneous microstructure originating from earlier Brownian dynamics\nsimulations. A systematic study of the elastic properties as a function of the\ndegree of heterogeneity was performed using two sets of microstructures\nobtained from Brownian dynamics simulation and from the void expansion method.\nBoth sets cover a broad and to a large extent overlapping range of degrees of\nheterogeneity. The simulations have shown that the elastic properties as a\nfunction of the degree of heterogeneity are independent of the structure\ngeneration algorithm and that the relation between the shear modulus and the\ndegree of heterogeneity can be well described by a power law. This suggests the\npresence of a critical degree of heterogeneity and, therefore, a phase\ntransition between a phase with finite and one with zero elastic properties."
    },
    {
        "anchor": "Filamentous Active Matter: Band Formation, Bending, Buckling, and\n  Defects: Motor proteins drive persistent motion and self-organisation of cytoskeletal\nfilaments. However, state-of-the-art microscopy techniques and continuum\nmodelling approaches focus on large length and time scales. Here, we perform\ncomponent-based computer simulations of polar filaments and molecular motors\nlinking microscopic interactions and activity to self-organisation and dynamics\nfrom the two-filament level up to the mesoscopic domain level. Dynamic filament\ncrosslinking and sliding, and excluded-volume interactions promote formation of\nbundles at small densities, and of active polar nematics at high densities. A\nbuckling-type instability sets the size of polar domains and the density of\ntopological defects. We predict a universal scaling of the active diffusion\ncoefficient and the domain size with activity, and its dependence on parameters\nlike motor concentration and filament persistence length. Our results provide a\nmicroscopic understanding of cytoplasmic streaming in cells and help to develop\ndesign strategies for novel engineered active materials.",
        "positive": "Solitons in a discrete model of chiral liquid crystals with competing\n  interactions: Chiral liquid crystals exhibit in-plane spontaneous polarizations, however in\ntheir smectic phase the primary order parameter is a tilt vector associated\nwith molecular rotations around the long molecular axis parallel to the\ndirector. The molecular rotations lead to several distinct phases among which a\ndomain-wall texture with a periodic-kink soliton profile. In this study the\nformation of domain walls in smectic chiral liquid crystals is analyzed, with\nemphasis on the competition between ising-type symmetric and antisymmetric\nnearest-neighbor interactions, and an in-plane electric field. It is found that\nantisymmetric intermolecular interactions, which are of chiral origin, increase\nthe width of kink structures in the domain wall at moderate intensity of the\n$y$ component of the electric field. Increasing the $x$ component of the\nelectric field creates unstable condition for soliton formation irrespective of\nmagnitudes of the symmetric and chiral intermolecular interactions. Stability\ncondition for single-kink domain-wall structures in the discrete molecular\nchain, is discussed by estimating the Peierls stress experienced by the\nsingle-kink soliton. Results suggest that chirality lowers the Peierls-Nabarro\nbarrier, hence increasing the lifetime of single-kink structures in the\ndiscrete medium."
    },
    {
        "anchor": "Activity induced turbulence in driven active matter: Turbulence in driven stratified active matter is considered. The relevant\nparameters characterizing the problem are the Reynolds number Re and an active\nmatter Richardson-like number,R. In the mixing limit,Re>>1, R<<1, we show that\nthe standard Kolmogorov energy spectrum 5/3 law is realized. On the other hand,\nin the stratified limit, Re>>1,R>>1, there is a new turbulence universality\nclass with a 7/5 law. The crossover from one regime to the other is discussed\nin detail. Experimental predictions and probes are also discussed.",
        "positive": "Regular and Chaotic States in a Local Map Description of Sheared Nematic\n  Liquid Crystals: We propose and study a local map capable of describing the full variety of\ndynamical states, ranging from regular to chaotic, obtained when a nematic\nliquid crystal is subjected to a steady shear flow. The map is formulated in\nterms of a quaternion parametrization of rotations of the local frame described\nby the axes of the nematic director, subdirector and the joint normal to these,\nwith two additional scalars describing the strength of ordering. Our model\nyields kayaking, wagging, tumbling, aligned and coexistence states, in\nagreement with previous formulations based on coupled ordinary differential\nequations. Such a map can serve as a building block for the construction of\nlattice models of the complex spatio-temporal states predicted for sheared\nnematics."
    },
    {
        "anchor": "Direct Test of Supercooled Liquid Scaling Relations: Diverse material classes exhibit practically identical behavior when made\nviscous upon cooling toward the glass transition, suggesting a common\ntheoretical basis. The first-principles scaling laws that have been proposed to\ndescribe the evolution with temperature have yet to be appropriately tested due\nto the extraordinary range of time scales involved. We used seven different\nmeasurement methods to determine the structural relaxation kinetics of a\nprototype molecular glass former over a temporal range of 13 decades and over a\ntemperature range spanning liquid to glassy states. For the material studied,\nour results comprise a comprehensive validation of the two scaling relations\nthat are central to the fundamental question of whether supercooled liquid\ndynamics can be described universally. The ultrabroadband mechanical\nmeasurements demonstrated have fundamental and practical applications in\npolymer science, geophysics, multifunctional materials, and other areas.",
        "positive": "Mechanics of cell integration in vivo: During embryonic development, regeneration and homeostasis, cells have to\nphysically integrate into their target tissues, where they ultimately execute\ntheir function. Despite a significant body of research on how mechanical forces\ninstruct cellular behaviors within the plane of an epithelium, very little is\nknown about the mechanical interplay at the interface between migrating cells\nand their surrounding tissue, which has its own dynamics, architecture and\nidentity. Here, using quantitative in vivo imaging and molecular perturbations,\ntogether with a theoretical model, we reveal that multiciliated cell (MCC)\nprecursors in the Xenopus embryo form dynamic filopodia that pull at the\nvertices of the overlying epithelial sheet to probe their stiffness and\nidentify the preferred positions for their integration into the tissue.\nMoreover, we report a novel function for a structural component of vertices,\nthe lipolysis-stimulated lipoprotein receptor (LSR), in filopodia dynamics and\nshow its critical role in cell intercalation. Remarkably, we find that pulling\nforces equip the MCCs to remodel the epithelial junctions of the neighboring\ntissue, enabling them to generate a permissive environment for their\nintegration. Our findings reveal the intricate physical crosstalk at the\ncell-tissue interface and uncover previously unknown functions for mechanical\nforces in orchestrating cell integration."
    },
    {
        "anchor": "Singular dynamics in the failure of soft adhesive contacts: We characterize the mechanical recovery of compliant silicone gels following\nadhesive contact failure. We establish broad, stable adhesive contacts between\nrigid microspheres and soft gels, then stretch the gels to large deformations\nby pulling quasi-statically on the contact. Eventually, the adhesive contact\nbegins to fail, and ultimately slides to a final contact point on the bottom of\nthe sphere. Immediately after detachment, the gel recoils quickly with a\nself-similar surface profile that evolves as a power law in time, suggesting\nthat the adhesive detachment point is singular. The singular dynamics we\nobserve are consistent with a relaxation process driven by surface stress and\nslowed by viscous flow through the porous, elastic network of the gel. Our\nresults emphasize the importance of accounting for both the liquid and solid\nphases of gels in understanding their mechanics, especially under extreme\ndeformation.",
        "positive": "Universality, scaling and collapse in supercritical fluids: The Supercritical Fluid (SCF) is known to exhibit salient dynamic and\nthermodynamic crossovers and inhomogeneous molecular distribution. But the\nquestion as to what basic physics underlies these microscopic and macroscopic\nanomalies remains open. Here, using an order parameter extracted by machine\nlearning, the fraction of gas-like (or liquid-like) molecules, we find\nsimplicity and universality in SCF: First, all isotherms of a given fluid\ncollapse onto a single master curve described by a scaling relation. The\nobserved power law holds from the high-temperature and pressure regime down to\nthe critical point where it diverges. Second, phase diagrams of different\ncompounds collapse onto their master curves by the same scaling exponent,\nthereby demonstrating a putative law of corresponding supercritical states in\nsimple fluids. The reported results support a model of the SCF as a mixture of\ntwo interchangeable microstates, whose spatiotemporal dynamics gives rise to\nunique macroscopic properties."
    },
    {
        "anchor": "A First-Principles Constitutive Equation for Suspension Rheology:\n  Supplementary Material: Additional supplementary material for the paper `A First-Principles\nConstitutive Equation for Suspension Rheology'.",
        "positive": "Coulomb friction in twisting of biomimetic scale-covered substrate: Biomimetic scale-covered substrates provide geometric tailorability via scale\norientation, spacing and also interfacial properties of contact in various\ndeformation modes. No work has investigated the effect of friction in twisting\ndeformation of biomimetic scale-covered beams. In this work, we investigate the\nfrictional effects in the biomimetic scale-covered structure by developing an\nanalytical model verified by the finite element simulations. In this model, we\nconsider dry (Coulomb) friction between rigid scales surfaces, and the\nsubstrate as the linear elastic rectangular beam. The obtained results show\nthat the friction has a dual contribution on the system by advancing the\nlocking mechanism due to change of mechanism from purely kinematic to\ninterfacial behavior, and stiffening the twist response due to increase the\nengagement forces. We also discovered, by increasing the coefficient of\nfriction using engineering scale surfaces to a critical coefficient, the system\ncould reach to an instantaneous post-engagement locking. The developed model\noutlines analytical relationships between geometry, deformation, frictional\nforce and kinematic energy, to design biomimetic scale-covered metamaterials\nfor a wide range of application."
    },
    {
        "anchor": "Water activity in lamellar stacks of lipid bilayers: \"Hydration forces\"\n  revisited: Water activity and its relationship with interactions stabilising lamellar\nstacks of mixed lipid bilayers in their fluid state are investigated by means\nof osmotic pressure measurements coupled with small-angle x-ray scattering. The\n(electrically-neutral) bilayers are composed of a mixture in various\nproportions of lecithin, a zwitterionic phospholipid, and Simulsol, a non-ionic\ncosurfactant with an ethoxylated polar head. For highly dehydrated samples the\nosmotic pressure profile always exhibits the \"classical\" exponential decay as\nhydration increases but, depending on Simulsol to lecithin ratio, it becomes\neither of the \"bound\" or \"unbound\" types for more water-swollen systems. A\nsimple thermodynamic model is used for interpreting the results without\nresorting to the celebrated but elusive \"hydration forces\"",
        "positive": "Multilayered crystals of macroions under slit-confinement: The crystalline ground state of macroions confined between two neutral\nparallel plates in the presence of their homogeneously spread counterions is\ncalculated by lattice-sum minimization of candidate phases involving up to six\nlayers. For increasing macroion density, a cascade of solid-solid transitions\nis found involving various multilayered crystals. The cascade includes\ntriangular monolayer and buckled bilayer as well as rhombic, squared and\ntriangular phase structures."
    },
    {
        "anchor": "Phase transition in a static granular system: We find that a column of glass beads exhibits a well-defined transition\nbetween two phases that differ in their resistance to shear. Pulses of\nfluidization are used to prepare static states with well-defined particle\nvolume fractions $\\phi$ in the range 0.57-0.63. The resistance to shear is\ndetermined by slowly inserting a rod into the column of beads. The transition\noccurs at $\\phi=0.60$ for a range of speeds of the rod.",
        "positive": "Single-file dynamics of colloids in circular channels: time scales,\n  scaling laws and their universality: In colloidal systems, Brownian motion emerges from the massive separation of\ntime and length scales associated to characteristic dynamics of the solute and\nsolvent constituents. This separation of scales produces several temporal\nregimes in the colloidal dynamics when combined with the effects of the\ninteraction between the particles, confinement conditions, and state variables,\nsuch as density and temperature. Some examples are the short- and long-time\nregimes in two- and three-dimensional open systems and the diffusive and\nsub-diffusive regimes observed in the single-file dynamics along a straight\nline. This work studies the way in which a confining geometry induces new time\nscales. We report on the dynamics of interacting colloidal particles moving\nalong a circle by combining a heuristic theoretical analysis of the involved\nscales, Brownian Dynamics computer simulations, and video-microscopy\nexperiments with paramagnetic colloids confined to lithographic circular\nchannels subjected to an external magnetic field. The systems display four\ntemporal regimes in this order: one-dimensional free diffusion, single-file\nsub-diffusion, free-cluster rotational diffusion, and the expected saturation\ndue to the confinement. We also report analytical expressions for the\nmean-square angular displacement and crossover times obtained from scaling\narguments, which accurately reproduce both experiments and simulations. Our\ngeneric approach can be used to predict the long-time dynamics of many other\nconfined physical systems."
    },
    {
        "anchor": "Line tensions, correlation lengths, and critical exponents in lipid\n  membranes near critical points: Membranes containing a wide variety of ternary mixtures of high chain-melting\ntemperature lipids, low chain-melting temperature lipids, and cholesterol\nundergo lateral phase separartion into coexisting liquid phases at a\nmiscibility transition. When membranes are prepared from a ternary lipid\nmixture at a critical composition, they pass through a miscibility critical\npoint at the transition temperature. Since the critical temperature is\ntypically on the order of room temperature, membranes provide an unusual\nopportunity in which to perform a quantitative study of biophysical systems\nthat exhibit critical phenomena in the two-dimensional Ising universality\nclass. As a critical point is approached from either high or low temperature,\nthe scale of fluctuations in lipid composition, set by the correlation length,\ndiverges. In addition, as a critical point is approached from low temperature,\nthe line tension between coexisting phases decreases to zero. Here we\nquantitatively evaluate the temperature dependence of line tension between\nliquid domains and of fluctuation correlation lengths in lipid membranes in\norder to extract a critical exponent, nu. We obtain nu=1.2 plus or minus 0.2,\nconsistent with the Ising model prediction nu=1. We also evaluate the\nprobability distributions of pixel intensities in fluoresence images of\nmembranes. From the temperature dependence of these distributions above the\ncritical temperature, we extract an independent critical exponent beta=0.124\nplus or minus 0.03 which is consistent with the Ising prediction of beta=1/8.",
        "positive": "Shape anisotropy of magnetic nanoparticles in\n  (Co$_{86}$Nb$_{12}$Ta$_2$)$_x$(SiO$_2$)$_{1-x}$ composite films revealed by\n  grazing-incidence small-angle X-ray scattering: Structure of amorphous nangranular composite\n(Co$_{86}$Nb$_{12}$Ta$_2$)$_x$(SiO$_2$)$_{1-x}$ films was studied by means of\ngrazing-incidence small-angle X-ray scattering as a function of atomic\nconcentration $x$ of the metal fraction in vicinity of the percolation\nthreshold. It has been established that the average size of magnetic\nnanoparticles increases with $x$ and this increment exhibit the anisotropic\ncharacter. It was found that in a whole concentration range the particles are\nelongated along the growth direction perpendicular to the film plane. For the\nlowest concentration $x=0.193$ clusters with isotropic shape and average radius\nof 1 nm were observed, while for higher concentrations up to $x=0.665$ the\naverage cluster length along the film normal is $1.5-7$ nm and the\ncross-section is $1-2$ nm."
    },
    {
        "anchor": "On the emergence of large and complex memory effects in nonequilibrium\n  fluids: Control of cooling and heating processes is essential in many industrial and\nbiological processes. In fact, the time evolution of an observable quantity may\ndiffer according to the previous history of the system. For example, a system\nthat is being subject to cooling and then, at a given time $t_{w}$ for which\nthe instantaneous temperature is $T(t_w)=T_{\\mathrm{st}}$, is suddenly put in\ncontact with a temperature source at $T_{\\mathrm{st}}$ may continue cooling\ndown temporarily or, on the contrary, undergo a temperature rebound. According\nto current knowledge, there can be only one \"spurious\" and small peak/low.\nHowever, our results prove that, under certain conditions, more than one\nextremum may appear. Specifically, we have observed regions with two extrema\nand a critical point with three extrema. We have also detected cases where\nextraordinarily large extrema are observed, as large as the order of magnitude\nof the stationary value of the variable of interest. We show this by studying\nthe thermal evolution of a low density set of macroscopic particles that do not\npreserve kinetic energy upon collision, i.e., a granular gas. We describe the\nmechanism that signals in this system the emergence of these complex and large\nmemory effects, and explain why similar observations can be expected in a\nvariety of systems.",
        "positive": "Dynamic Control of Particle Deposition in Evaporating Droplets by an\n  External Point Source of Vapor: The deposition of particles on a surface by an evaporating sessile droplet is\nimportant for phenomena as diverse as printing, thin-film deposition and\nself-assembly. The shape of the final deposit depends on the flows within the\ndroplet during evaporation. These flows are typically determined at the onset\nof the process by the intrinsic physical, chemical and geometrical properties\nof the droplet and its environment. Here, we demonstrate deterministic\nemergence and real-time control of Marangoni flows within the evaporating\ndroplet by an external point-source of vapor. By varying the source location,\nwe can modulate these flows in space and time to pattern colloids on surfaces\nin a controllable manner."
    },
    {
        "anchor": "Instabilities in freely expanding sheets of associating viscoelastic\n  fluids: We use the impact of drops on a small solid target as a tool to investigate\nthe behavior of viscoelastic fluids under extreme deformation rates. We study\ntwo classes of transient networks: semidilute solutions of supramolecular\npolymers and suspensions of spherical oil droplets reversibly linked by\npolymers. The two types of samples display very similar linear viscoelastic\nproperties, which can be described with a Maxwell fluid model, but contrasting\nnonlinear properties due to different network structure. Upon impact, weakly\nviscoelastic samples exhibit a behavior qualitatively similar to that of\nNewtonian fluids: A smooth and regular sheet forms, expands, and then retracts.\nBy contrast, for highly viscoelastic fluids, the thickness of the sheet is\nfound to be very irregular, leading to instabilities and eventually formation\nof holes. We find that material rheological properties rule the onset of\ninstabilities. We first provide a simple image analysis of the expanding sheets\nto determine the onset of instabilities. We then demonstrate that a Deborah\nnumber related to the shortest relaxation time associated to the sample\nstructure following a high shear is the relevant parameter that controls the\nheterogeneities in the thickness of the sheet, eventually leading to the\nformation of holes. When the sheet tears-up, data suggest by contrast that the\nopening dynamics depends also on the expansion rate of the sheet.",
        "positive": "Arrest of Fluid Demixing by Nanoparticles: A Computer Simulation Study: We use lattice Boltzmann simulations to investigate the formation of arrested\nstructures upon demixing of a binary solvent containing neutrally wetting\ncolloidal particles. Previous simulations for symmetric fluid quenches pointed\nto the formation of `bijels': bicontinuous interfacially jammed emulsion gels.\nThese should be created when a glassy monolayer of particles forms at the\nfluid-fluid interface, arresting further demixing, and rigidifying the\nstructure. Experimental work has broadly confirmed this scenario, but shows\nthat bijels can also be formed in volumetrically asymmetric quenches. Here we\npresent new simulation results for such quenches, compare these to the\nsymmetric case, and find a crossover to an arrested droplet phase at strong\nasymmetry. We then make extensive new analyses of the post-arrest dynamics in\nour simulated bijel and droplet structures, on time scales comparable to the\nBrownian time for colloid motion. Our results suggest that, on these\nintermediate time scales, the effective activation barrier to ejection of\nparticles from the fluid-fluid interface is smaller by at least two orders of\nmagnitude than the corresponding barrier for an isolated particle on a flat\ninterface."
    },
    {
        "anchor": "Polymer chain collapse induced by many-body dipole correlations: We present a simple analytical theory of flexible polymer chain dissolved in\na good solvent, carrying permanent freely oriented dipoles on the monomers. We\ntake into account the dipole correlations within the random phase approximation\n(RPA), as well as a dielectric heterogeneity in the internal polymer volume\nrelative to the bulk solution. We demonstrate that the dipole correlations of\nmonomers can be taken into account as pairwise ones only when the polymer chain\nis in a coil conformation. In this case the dipole correlations manifest\nthemselves through the Keesom interactions of the permanent dipoles. On the\nother hand, the dielectric heterogeneity effect (dielectric mismatch effect)\nleads to effective interaction between the monomers of the polymeric coil. Both\nof these effects can be taken into account by the renormalizing the second\nvirial coefficient of the volume interactions monomer-monomer. We establish\nthat in the case when the solvent dielectric permittivity exceeds the\ndielectric permittivity of the polymeric material, the dielectric mismatch\neffect competes with the dipole attractive interactions, leading to polymer\ncoil expansion. In the opposite case, both the dielectric mismatch effect and\nthe dipole attractive interaction lead to the polymer coil collapse. We analyse\nthe coil-globule transition caused by the dipole correlations of monomers\nwithin the many-body theory. We demonstrate that accounting for the dipole\ncorrelations higher than pairwise ones smooths this pure electrostatics driven\ncoil-globule transition of the polymer chain.",
        "positive": "Array of Bose-Einstein condensates under time-periodic\n  Feshbach-resonance management: The dynamics of a discrete soliton in an array of Bose-Einstein condensates\nunder the action of a periodically time-modulated atomic scattering length\n(``Feshbach-resonance management, FRM'') is investigated. The cases of both\nslow and rapid modulation, in comparison with the tunneling frequency, are\nconsidered. We employ a discrete variational approach for the analysis of the\nsystem. The existence of nonlinear resonances and chaos is predicted at special\nvalues of the driving frequency. Soliton splitting is observed in numerical\nsimulations. In the case of the rapid modulation, we derive an averaged\nequation, which is a generalized discrete nonlinear Schroedinger equation,\nincluding higher-order effective nonlinearities and intersite nonlinear\ninteractions. Thus the predicted discrete FRM solitons are a direct matter-wave\nanalog of recently investigated discrete diffraction-managed optical solitons."
    },
    {
        "anchor": "Stationary states and energy cascades in inelastic gases: We find a general class of nontrivial stationary states in inelastic gases\nwhere, due to dissipation, energy is transfered from large velocity scales to\nsmall velocity scales. These steady-states exist for arbitrary collision rules\nand arbitrary dimension. Their signature is a stationary velocity distribution\nf(v) with an algebraic high-energy tail, f(v) ~ v^{-sigma}. The exponent sigma\nis obtained analytically and it varies continuously with the spatial dimension,\nthe homogeneity index characterizing the collision rate, and the restitution\ncoefficient. We observe these stationary states in numerical simulations in\nwhich energy is injected into the system by infrequently boosting particles to\nhigh velocities. We propose that these states may be realized experimentally in\ndriven granular systems.",
        "positive": "Instabilities in Granular Flow: We consider the stability of a system of equations which are a singular\nperturbation of the incompressible rigid-plastic flow equations used to model\ngranular flow. A linear stability analysis shows that solutions of these\nequations are unstable, in general, and that these instabilities may lead to\nill-posedness. However, the analysis suggests that these equations are more\nregular, in a certain sense, than the unperturbed incompressible rigid-plastic\nflow equations. Numerical solutions are presented which illustrate the growth\nof instabilities and the development of shear-bands in the flows."
    },
    {
        "anchor": "What is in a pebble shape?: We propose to characterize the shapes of flat pebbles in terms of the\nstatistical distribution of curvatures measured along the pebble contour. This\nis demonstrated for the erosion of clay pebbles in a controlled laboratory\napparatus. Photographs at various stages of erosion are analyzed, and compared\nwith two models. We find that the curvature distribution complements the usual\nmeasurement of aspect ratio, and connects naturally to erosion processes that\nare typically faster at protruding regions of high curvature.",
        "positive": "Experimental and computational studies of jamming: Jamming is a common feature of out of equilibrium systems showing slow\nrelaxation dynamics. Here we review our efforts in understanding jamming in\ngranular materials using experiments and computer simulations. We first obtain\nan estimation of an effective temperature for a slowly sheared granular\nmaterial very close to jamming. The measurement of the effective temperature is\nrealized in the laboratory by slowly shearing a closely-packed ensemble of\nspherical beads confined by an external pressure in a Couette geometry. All the\nprobe particles, independent of their characteristic features, equilibrate at\nthe same temperature, given by the packing density of the system. This suggests\nthat the effective temperature is a state variable for the nearly jammed\nsystem. Then we investigate numerically whether the effective temperature can\nbe obtained from a flat average over the jammed configuration at a given energy\nin the granular packing, as postulated by the thermodynamic approach to grains."
    },
    {
        "anchor": "A theoretical study on the dynamics of a compound vesicle in linear\n  shear flow: The dynamics of a nucleate cell in shear flow is of great relevance in cancer\ncells and circulatory tumor cells where they dominate the dynamics of blood.\nBuoyed by the success of Giant Unilamellar vesicles in explaining the dynamics\nof anucleate cells such as Red Blood cells, compound vesicles have been\nsuggested as a simple model for nucleate cells. In this work, a theoretical\nmodel is presented to study the deformation and dynamics of a compound vesicle\nin linear shear flow using small deformation theory and spherical harmonics\nwith higher order approximation to the membrane forces. The results indicate\nthat size of the inner vesicle does not affect the tank-treading dynamics of\nthe outer vesicle. The inner vesicle admits a greater inclination angle than\nthe outer vesicle. However, the transition to trembling-swinging and tumbling\nis significantly affected. The inner and outer vesicle exhibit identical\ndynamics in most of the modified viscosity-shear rate parameter space. At\nmoderate size of the inner vesicle, a swinging mode is observed for the inner\nvesicle while the outer vesicle exhibits tumbling. The inner vesicle also\nexhibits modification of the TU mode to IUS-Intermediate Tumbling Swinging\nmode. Moreover, synchronization of the two vesicles at higher inner vesicle\nsize and a capillary number sensitive motion at small inner vesicle size is\nobserved in the tumbling regime. These results are in accordance with the few\nexperimental observations reported by Levant and Steinberg2014. A reduction in\nthe inclination angle is observed with an increase in size of the inner vesicle\nwhen the inner vesicle is a solid inclusion. Additionally a very elaborate\nphase diagram is presented in the modified viscosity-shear rate parameter\nspace, which could be tested in future experiments or numerical simulations",
        "positive": "Quasi-Random Lattice Model for Electrolyte Solutions: State of Art and\n  Future Perspectives: In this work, the Quasi-Random Lattice (QRL) model is summarized and\ncritically discussed, in order to outline its potentialities and limitations,\nin perspective of future developments. QRL primarily focuses on the mean\nactivity coefficient of ionic solutions, the model having first been developed\nin order to provide practical equations, able to involve a minimal number of\nunknown or unpredictable quantities. QRL at present depends on one adjustable\nparameter (at given pressure and temperature), experimentally known for many\ncommon salts either symmetric or asymmetric, and corresponding to a\nwell-defined concentration, which also sets the upper limit of applicability of\nthe model. For aqueous electrolytes, the concentration-parameter ranges from 1\nM to 8 M (about). In the following it will be seen that, although belonging to\nthe class of simplified approaches, QRL can provide very interesting results\nsince its simple parametrisation is more significant, from a theoretical point\nof view, than so far recognized. A general overview of the QRL theory will\nfirst be presented. Then, some preliminary results will be discussed, in\nparticular concerned with volumetric and thermal properties of electrolyte\nsolutions."
    },
    {
        "anchor": "An Abelian Higgs model for disclinations in nematics: Topological defects in elastic media may be described by a geometric field\nakin to three-dimensional gravity. From this point of view, disclinations are\nline defects of zero width corresponding to a singularity of the curvature in\nan otherwise flat background. On the other hand, in two dimensions, the Frank\nfree energy of a nematic liquid crystal may be interpreted as an Abelian Higgs\nLagrangian. In this work, we construct an Abelian Higgs model coupled to\n\"gravity\" for the nematic phase, with the perspective of finding more realistic\ndisclinations. That is, a cylindrically symmetric line defect of finite radius,\ninvariant under translations along its axis. Numerical analysis of the\nequations of motion indeed yield a $+1$ winding number \"thick\" disclination.\nThe defect is described jointly by the gauge and the Higgs fields, that compose\nthe director field, and the background geometry. Away from the defect, the\ngeometry is conical, associated to a dihedral deficit angle. The gauge field,\nconfined to the defect, gives a structure to the disclination while the Higgs\nfield, outside, represents the nematic order.",
        "positive": "Liquid-liquid phase transition model incorporating evidence for\n  ferroelectric state near the lambda-point anomaly in supercooled water: We propose a unified model combining the first-order liquid-liquid and the\nsecond-order ferroelectric phase transitions models and explaining various\nfeatures of the $\\lambda$-point of liquid water within a single theoretical\nframework. It becomes clear within the proposed model that not only does the\nlong-range dipole-dipole interaction of water molecules yield a large value of\ndielectric constant $\\epsilon$ at room temperatures, our analysis shows that\nthe large dipole moment of the water molecules also leads to a ferroelectric\nphase transition at a temperature close to the lambda-point. Our more refined\nmodel suggests that the phase transition occurs only in the low density\ncomponent of the liquid and is the origin of the singularity of the dielectric\nconstant recently observed in experiments with supercooled liquid water at\ntemperature T~233K. This combined model agrees well with nearly every available\nset of experiments and explains most of the well-known and even recently\nobtained results of MD simulations."
    },
    {
        "anchor": "Dynamics of lane formation in driven binary complex plasmas: The dynamical onset of lane formation is studied in experiments with binary\ncomplex plasmas under microgravity conditions. Small microparticles are driven\nand penetrate into a cloud of big particles, revealing a strong tendency\ntowards lane formation. The observed time-resolved lane formation process is in\ngood agreement with computer simulations of a binary Yukawa model with Langevin\ndynamics. The laning is quantified in terms of the anisotropic scaling index,\nleading to a universal order parameter for driven systems.",
        "positive": "Dipolar interactions, molecular flexibility, and flexoelectricity in\n  bent-core liquid crystals: The effects of dipolar interactions and molecular flexibility on the\nstructure and phase behavior of bent-core molecular fluids are studied using\nMonte Carlo computer simulations. Some calculations of flexoelectric\ncoefficients are also reported. The rigid cores of the model molecules consist\nof either five or seven soft spheres arranged in a `V' shape with external bend\nangle $\\gamma$. With purely repulsive sphere-sphere interactions and\n$\\gamma=0^\\circ$ (linear molecules) the seven-sphere model exhibits isotropic,\nuniaxial nematic, smectic-A, and tilted phases. With $\\gamma \\geq 20^\\circ$ the\nsmectic-A phase disappears, while the system with $\\gamma \\geq 40^\\circ$ shows\na direct tilted smectic--isotropic fluid transition. The addition of\nelectrostatic interactions between transverse dipole moments on the apical\nspheres is generally seen to reduce the degree of tilt in the smectic and solid\nphases, destabilize the nematic and smectic-A phases of linear molecules, and\ndestabilize the tilted smectic-B phase of bent-core molecules. The effects of\nadding three-segment flexible tails to the ends of five-sphere bent-core\nmolecules are examined using configurational-bias Monte Carlo simulations. Only\nisotropic and smectic phases are observed. On the one hand, molecular\nflexibility gives rise to pronounced fluctuations in the smectic-layer\nstructure, bringing the simulated system in better correspondence with real\nmaterials; on the other hand, the smectic phase shows almost no tilt. Lastly,\nthe flexoelectric coefficients of various nematic phases -- with and without\nattractive sphere-sphere interactions -- are presented. The results are\nencouraging, but the computational effort required is a drawback associated\nwith the use of fluctuation relations."
    },
    {
        "anchor": "Direct numerical simulations of aeolian sand ripples: Aeolian sand beds exhibit regular patterns of ripples resulting from the\ninteraction between topography and sediment transport. Their characteristics\nhave been so far related to reptation transport caused by the impacts on the\nground of grains entrained by the wind into saltation. By means of direct\nnumerical simulations of grains interacting with a wind flow, we show that the\ninstability turns out to be driven by resonant grain trajectories, whose length\nis close to a ripple wavelength and whose splash leads to a mass displacement\ntowards the ripple crests. The pattern selection results from a compromise\nbetween this destabilizing mechanism and a diffusive downslope transport which\nstabilizes small wavelengths. The initial wavelength is set by the ratio of the\nsediment flux and the erosion/deposition rate, a ratio which increases linearly\nwith the wind velocity. We show that this scaling law, in agreement with\nexperiments, originates from an interfacial layer separating the saltation zone\nfrom the static sand bed, where momentum transfers are dominated by mid-air\ncollisions. Finally, we provide quantitative support for the use the\npropagation of these ripples as a proxy for remote measurements of sediment\ntransport.",
        "positive": "Hydrodynamical random walker with chemotactic memory: A three-dimensional hydrodynamical model for a micro random walker is\ncombined with the idea of chemotactic signaling network of E. coli. Diffusion\nexponents, orientational correlation functions and their dependence on the\ngeometrical and dynamical parameters of the system are analyzed numerically.\nBecause of the chemotactic memory, the walker shows superdiffusing\ndisplacements in all directions with the largest diffusion exponent for a\ndirection along the food gradient. Mean square displacements and orientational\ncorrelation functions show that the chemotactic memory washes out all the\nsignatures due to the geometrical asymmetry of the walker and statistical\nproperties are asymmetric only with respect to the direction of food gradient.\nFor different values of the memory time, the Chemotactic index (CI) is also\ncalculated."
    },
    {
        "anchor": "Dynamics of sliding drops on superhydrophobic surfaces: We use a free energy lattice Boltzmann approach to investigate numerically\nthe dynamics of drops moving across superhydrophobic surfaces. The surfaces\ncomprise a regular array of posts small compared to the drop size. For drops\nsuspended on the posts the velocity increases as the number of posts decreases.\nWe show that this is because the velocity is primarily determined by the\ncontact angle which, in turn, depends on the area covered by posts. Collapsed\ndrops, which fill the interstices between the posts, behave in a very different\nway. The posts now impede the drop behaviour and the velocity falls as their\ndensity increases.",
        "positive": "Modeling Growth Paths of Interacting Crack Pairs in Elastic Media: The problem of predicting the growth of a system of cracks, each crack\ninfluencing the growth of the others, arises in multiple fields. We develop an\nanalytical framework toward this aim, which we apply to the `En-Passant' family\nof crack growth problems, in which a pair of initially parallel, offset cracks\npropagate nontrivially toward each other under far-field opening stress. We\nutilize boundary integral and perturbation methods of linear elasticity, Linear\nElastic Fracture Mechanics, and common crack opening criteria to calculate the\nfirst analytical model for curved En-Passant crack paths. The integral system\nis reduced under a hierarchy of approximations, producing three methods of\nincreasing simplicity for computing crack paths. The last such method is a\nmajor highlight of this work, using an asymptotic matching argument to predict\ncrack paths based on superposition of simple, single-crack fields. Within the\ncorresponding limits of the three methods, all three are shown to agree with\neach other. We provide comparisons to exact results and existing experimental\ndata to verify certain approximation steps."
    },
    {
        "anchor": "Anomalous Diffusion in a Bench-Scale Pulsed Fluidized Bed: We present our analysis on micro-rheology of a bench-scale pulsed fluidized\nbed, which represents a weakly confined system. Non-linear gas-particle and\nparticle-particle interactions resulting from pulsed flow are associated with\nharmonic and sub-harmonic modes. While periodic structured bubble patterns are\nobserved at the meso-scale, particle-scale measurements reveal anomolous\ndiffusion in the driven granular medium. We use single-particle tracks to\nanalyze ergodicity and ageing properties at two pulsing frequencies having\nremarkably different meso-scale features. The scaling of ensemble-averaged mean\nsquared displacement is not unique. The distribution of time-averaged mean\nsquared displacements is non-Gaussian, asymmetric and has a finite trivial\ncontribution from particles in crowded quasi-static surroundings. Results\nindicate weak ergodicity breaking which along with ageing characterize the\nnon-stationary and out-of-equilibrium dynamics.",
        "positive": "Structure of polymer layers grafted to nanoparticles in\n  silica-polystyrene nanocomposites: The structural features of polystyrene brushes grafted on spherical silica\nnanoparticles immersed in polystyrene are investigated by means of a Monte\nCarlo methodology based on polymer mean field theory. The nanoparticle radii\n(either 8 nm or 13 nm) are held constant, while the grafting density and the\nlengths of grafted and matrix chains are varied systematically in a series of\nsimulations. The primary objective of this work is to simulate realistic\nnanocomposite systems of specific chemistry at experimentally accessible length\nscales and study the structure and scaling of the grafted brush. The profiles\nof polymer density around the particles are examined; based on them, the brush\nthickness of grafted chains is estimated and its scaling behavior is compared\nagainst theoretical models and experimental findings. Then, neutron scattering\nspectra are predicted both from single grafted chains and from the entire\ngrafted corona. It is found that increasing both the grafting density and the\ngrafted chain molar mass drastically alters the brush dimensions, affecting the\nwetting behavior of the polymeric brush. On the contrary, especially for\nparticles dispersed in high molecular weight matrix, variation of the matrix\nchain length causes an almost imperceptible change of the density around the\nparticle surface."
    },
    {
        "anchor": "Semidilute Polymer Solutions at Equilibrium and under Shear Flow: The properties of semidilute polymer solutions are investigated at\nequilibrium and under shear flow by mesoscale simulations, which combine\nmolecular dynamics simulations and the multiparticle collision dynamics\napproach. In semidilute solution, intermolecular hydrodynamic and excluded\nvolume interactions become increasingly important due to the presence of\npolymer overlap. At equilibrium, the dependence of the radius of gyration, the\nstructure factor, and the zero-shear viscosity on the polymer concentration is\ndetermined and found to be in good agreement with scaling predictions. In shear\nflow, the polymer alignment and deformation are calculated as a function of\nconcentration. Shear thinning, which is related to flow alignment and finite\npolymer extensibility, is characterized by the shear viscosity and the normal\nstress coefficients.",
        "positive": "Intruder mobility in a vibrated granular packing: We study experimentally the dynamics of a dense intruder sinking under\ngravity inside a vibrated 2D granular packing. The surrounding flow patterns\nare characterized and the falling trajectories are interpreted in terms of an\neffectivive friction coefficient related to the intruder mean descent velocity\n(flow rules). At higher confining pressures i.e. close to jamming, a transition\nto intermittent dynamics is evidenced and displays anomalous \"on-off\" blockade\nstatistics. A systematic analysis of the flow rules, obtained for different\nintruder sizes, either in the flowing regime or averaged over the flowing and\nblockade regimes, strongly suggest the existence of non-local properties for\nthe vibrated packing rheology.}"
    },
    {
        "anchor": "Velocity autocorrelation function of a Brownian particle: In this article, we present molecular dynamics study of the velocity\nautocorrelation function (VACF) of a Brownian particle. We compare the results\nof the simulation with the exact analytic predictions for a compressible fluid\nfrom [6] and an approximate result combining the predictions from hydrodynamics\nat short and long times. The physical quantities which determine the decay were\ndetermined from separate bulk simulations of the Lennard-Jones fluid at the\nsame thermodynamic state point.We observe that the long-time regime of the VACF\ncompares well the predictions from the macroscopic hydrodynamics, but the\nintermediate decay is sensitive to the viscoelastic nature of the solvent.",
        "positive": "Structuring polymer gels via catalytic reactions: We use computer simulations to investigate how a catalytic reaction in a\npolymer sol can induce the formation of a polymer gel. To this aim we consider\na solution of homopolymers in which freely-diffusing catalysts convert the\noriginally repulsive A monomers into attractive B ones. We find that at low\ntemperatures this reaction transforms the polymer solution into a physical gel\nthat has a remarkably regular mesostructure in the form of a cluster phase,\nabsent in the usual homopolymer gels obtained by a quench in temperature. We\ninvestigate how this microstructuring depends on catalyst concentration,\ntemperature, and polymer density and show that the dynamics for its formation\ncan be understood in a semi-quantitative manner using the interaction\npotentials between the particles as input. The structuring of the copolymers\nand the AB sequences resulting from the reactions can be discussed in the\ncontext of the phase behaviour of correlated random copolymers. The location of\nthe spinodal line as found in our simulations is consistent with analytical\npredictions. Finally, we show that the observed structuring depends not only on\nthe chemical distribution of the A and B monomers but also on the mode of\nformation of this distribution."
    },
    {
        "anchor": "Structural transformation in supercooled water controls the\n  crystallization rate of ice: One of water's unsolved puzzles is the question of what determines the lowest\ntemperature to which it can be cooled before freezing to ice. The supercooled\nliquid has been probed experimentally to near the homogeneous nucleation\ntemperature TH{\\approx}232 K, yet the mechanism of ice crystallization -\nincluding the size and structure of critical nuclei - has not yet been\nresolved. The heat capacity and compressibility of liquid water anomalously\nincrease upon moving into the supercooled region according to a power law that\nwould diverge at Ts{\\approx}225 K,(1,2) so there may be a link between water's\nthermodynamic anomalies and the crystallization rate of ice. But probing this\nlink is challenging because fast crystallization prevents experimental studies\nof the liquid below TH. And while atomistic studies have captured water\ncrystallization(3), the computational costs involved have so far prevented an\nassessment of the rates and mechanism involved. Here we report coarse-grained\nmolecular simulations with the mW water model(4) in the supercooled regime\naround TH, which reveal that a sharp increase in the fraction of\nfour-coordinated molecules in supercooled liquid water explains its anomalous\nthermodynamics and also controls the rate and mechanism of ice formation. The\nsimulations reveal that the crystallization rate of water reaches a maximum\naround 225 K, below which ice nuclei form faster than liquid water can\nequilibrate. This implies a lower limit of metastability of liquid water just\nbelow TH and well above its glass transition temperature Tg{\\approx}136 K. By\nproviding a relationship between the structural transformation in liquid water,\nits anomalous thermodynamics and its crystallization rate, this work provides a\nmicroscopic foundation to the experimental finding that the thermodynamics of\nwater determines the rates of homogeneous nucleation of ice.(5)",
        "positive": "Forceless Sadowsky strips are spherical: We show that thin rectangular ribbons, defined as energy-minimising\nconfigurations of the Sadowsky functional for narrow developable elastic\nstrips, have a propensity to form spherical shapes in the sense that forceless\nsolutions lie on a sphere. This has implications for ribbonlike objects in\n(bio)polymer physics and nanoscience that cannot be described by the classical\nwormlike chain model. A wider class of functionals with this property is\nidentified."
    },
    {
        "anchor": "Vesicle propulsion in haptotaxis : a local model: We study theoretically vesicle locomotion due to haptotaxis.\n  Haptotaxis is referred to motion induced by an adhesion gradient on a\nsubstrate. The problem is solved within a local approximation where a\nRayleigh-type dissipation is adopted. The dynamical model is akin to the Rousse\nmodel for polymers. A powerful gauge-field invariant formulation is used to\nsolve a dynamical model which includes a kind of dissipation due to bond\nbreaking/restoring with the substrate. For a stationary situation where the\nvesicle acquires a constant drift velocity, we formulate the propulsion problem\nin terms of a nonlinear eigenvalue (the a priori unknown drift velocity) one of\nBarenblat-Zeldovitch type. A counting argument shows that the velocity belongs\nto a discrete set. For a relatively tense vesicle, we provide an analytical\nexpression for the drift velocity as a function of relevant parameters. We find\ngood agreement with the full numerical solution. Despite the oversimplification\nof the model it allows the identification of a relevant quantity, namely the\nadhesion length, which turns out to be crucial also in the nonlocal model in\nthe presence of hydrodynamics, a situation on which we have recently reported\n[I. Cantat, and C. Misbah, Phys. Rev. Lett. {\\bf 83}, 235 (1999)] and which\nconstitutes the subject of a forthcoming extensive study.",
        "positive": "Spontaneous chiral symmetry breaking in model bacterial suspensions: Chiral symmetry breaking is ubiquitous in biological systems, from DNA to\nbacterial suspensions. A key unresolved problem is how chiral structures may\nspontaneously emerge from achiral interactions. We study a simple model of\nbacterial suspensions in three dimensions that effectively incorporates active\nmotion and hydrodynamic interactions. We perform large-scale molecular dynamics\nsimulations (up to $10^6$ particles) and describe stable (or long-lived\nmetastable) collective states that exhibit chiral organization although the\ninteractions are achiral. We elucidate under which conditions these chiral\nstates will emerge and grow to large scales. We also study a related\nequilibrium model that clarifies the role of orientational fluctuations."
    },
    {
        "anchor": "Microfluidic Thin Film Pressure Balance for the Study of Complex Thin\n  Films: Investigations of free-standing liquid films enjoy an increasing popularity\ndue to their relevance for many fundamental and applied scientific problems.\nThey constitute soap bubbles and foams, serve as membranes for gas transport or\nas model membranes in biophysics. More generally, they provide a convenient\ntool for the investigation of numerous fundamental questions related to\ninterface-and confinement-driven effects in soft matter science. Several\napproaches and devices have been developed in the past to characterise reliably\nthe thinning and stability of such films, which were commonly created from\nlow-viscosity, aqueous solutions/dispersions. With an increasing interest in\nthe investigation of films made from strongly viscoelastic and complex fluids\nthat may also solidify, the development of a new generation of devices is\nrequired to manage reliably the constraints imposed by these formulations. We\ntherefore propose here a microfluidic chip design which allows for the reliable\ncreation, control and characterisation of free-standing films of complex\nfluids. We provide all technical details and we demonstrate the device\nfunctioning for a larger range of systems via a selection of illustrative\nexamples, including films of polymer melts and gelling hydrogels.",
        "positive": "Equivalence between random close packing in granular matter and freezing\n  in the hard sphere model: The notion of random close packings of a bulk static collection of ball\nbearings or sand grains was introduced in the 1960's by G.D. Scott and J.D.\nBernal. There have been numerous attempts to understand the packings. We give a\nshort argument, based on recent experiments and simulations, which explains the\npackings in purely geometric terms."
    },
    {
        "anchor": "Non-locality and viscous drag effects on the shear localisation in\n  soft-glassy materials: We study the Couette flow of a quasi-2d soft-glassy material in a Hele-Shaw\ngeometry. The material is chosen to be above the jamming point, where a yield\nstress $\\sigma_Y$ emerges, below which the material deforms elastically and\nabove which it flows like a complex fluid according to a Herschel-Bulkley (HB)\nrheology. Simultaneously, the effect of the confining plates is modelled as an\neffective linear friction law, while the walls aside the Hele-Shaw cell are\nsufficiently close to each other to allow visible cooperativity effects in the\nvelocity profiles (Goyon et al., Nature 454, 84-87 (2008)). The effects of\ncooperativity are parametrized with a steady-state diffusion-relaxation\nequation for the fluidity field $f = \\dot{\\gamma}/\\sigma$, defined as the ratio\nbetween shear rate $\\dot{\\gamma}$ and shear stress $\\sigma$. For particular\nrheological flow-curves (Bingham fluids), the problem is tackled analytically:\nwe explore the two regimes $\\sigma \\gg \\sigma_Y$ and $\\sigma \\approx \\sigma_Y$\nand quantify the effect of the extra localisation induced by the wall friction.\nOther rheo-thinning fluids are explored with the help of numerical simulations\nbased on lattice Boltzmann models, revealing a robustness of the analytical\nfindings. Synergies and comparisons with other existing works in the literature\n(Barry et al., Phil. Mag. Lett. 91, 432-440 (2011)) are also discussed.",
        "positive": "Boundary behaviours of open vesicles in axisymmetric case: A continuous transformation from a closed vesicle to an open vesicle needs\nthat the area of open hole enlarge from zero. Since the shape equation and\nboundary conditions of lipid open vesicles with free edges have been obtained,\nwe want know whether this process can be archived with valid parameters. By\nstudy the boundary conditions in the axisymmetric case, the analytic expression\nof the boundary edges is obtained generally. It reveals that the radius and\nline tension of boundary edges are confined strongly by bending moduli. In some\ncases, there is the minimal nonzero boundary radius and the line tension needs\nto surmount the maxim following the increase of boundary radius. Without the\nspontaneous curvature, the line tension will trend to infinite when the\nboundary radius shrinks to zero. The continuous opening process from a closed\nvesicle to an open vesicle needs that the spontaneous curvature is nonzero and\nthe ratio between the bending moduli of Gauss curvature and mean curvature\nsatisfies $k\\leq-4$. Besides the line tension, a closed vesicle can be opened\nthrough changing the spontaneous curvature."
    },
    {
        "anchor": "Coarse-grained model of adsorption of blood plasma proteins onto\n  nanoparticles: We present a coarse-grained model for evaluation of interactions of globular\nproteins with nanoparticles. The protein molecules are represented by one bead\nper aminoacid and the nanoparticle by a homogeneous sphere that interacts with\nthe aminoacids via a central force that depends on the nanoparticle size. The\nproposed methodology is used to predict the adsorption energies for six common\nhuman blood plasma proteins on hydrophobic charged or neutral nanoparticles of\ndifferent sizes as well as the preferred orientation of the molecules upon\nadsorption. Our approach allows one to rank the proteins by their binding\naffinity to the nanoparticle, which can be used for predicting the composition\nof the NP-protein corona. The predicted ranking is in good agreement with known\nexperimental data for protein adsorption on surfaces.",
        "positive": "Dynamic correlations in stochastic rotation dynamics: The dynamic structure factor, vorticity and entropy density dynamic\ncorrelation functions are measured for Stochastic Rotation Dynamics (SRD), a\nparticle based algorithm for fluctuating fluids. This allows us to obtain\nunbiased values for the longitudinal transport coefficients such as thermal\ndiffusivity and bulk viscosity. The results are in good agreement with earlier\nnumerical and theoretical results, and it is shown for the first time that the\nbulk viscosity is indeed zero for this algorithm. In addition, corrections to\nthe self-diffusion coefficient and shear viscosity arising from the breakdown\nof the molecular chaos approximation at small mean free paths are analyzed. In\naddition to deriving the form of the leading correlation corrections to these\ntransport coefficients, the probabilities that two and three particles remain\ncollision partners for consecutive time steps are derived analytically in the\nlimit of small mean free path. The results of this paper verify that we have an\nexcellent understanding of the SRD algorithm at the kinetic level and that\nanalytic expressions for the transport coefficients derived elsewhere do indeed\nprovide a very accurate description of the SRD fluid."
    },
    {
        "anchor": "Porous Superhydrophobic Membranes: Hydrodynamic Anomaly in Oscillating\n  Flows: We have fabricated and characterized a novel superhydrophobic system, a\nmesh-like porous superhydrophobic membrane with solid area fraction $\\Phi_s$,\nwhich can maintain intimate contact with outside air and water reservoirs\nsimultaneously. Oscillatory hydrodynamic measurements on porous\nsuperhydrophobic membranes as a function of $\\Phi_s$ reveal surprising effects.\nThe hydrodynamic mass oscillating in-phase with the membranes stays constant\nfor $0.9\\le\\Phi_s\\le1$, but drops precipitously for $\\Phi_s < 0.9$. The viscous\nfriction shows a similar drop after a slow initial decrease proportional to\n$\\Phi_s$. We attribute these effects to the percolation of a stable Knudsen\nlayer of air at the interface.",
        "positive": "Spatially resolved x-ray studies of liquid crystals with strongly\n  developed bond-orientational order: We present an x-ray study of freely suspended hexatic films of the liquid\ncrystal 3(10)OBC. Our results reveal spatial inhomogeneities of the\nbond-orientational (BO) order in the vicinity of the hexatic-smectic phase\ntransition and the formation of large scale hexatic domains at lower\ntemperatures. Deep in the hexatic phase up to 25 successive sixfold BO order\nparameters have been directly determined by means of angular x-ray\ncross-correlation analysis (XCCA). Such strongly developed hexatic order\nallowed us to determine higher order correction terms in the scaling relation\npredicted by the multicritical scaling theory over a full temperature range of\nthe hexatic phase existence."
    },
    {
        "anchor": "Effective Hamiltonian for a liquid-gas interface fluctuating around a\n  corrugated cylindrical substrate in the presence of van der Waals\n  interactions: We investigate liquid layers adsorbed at spherical and corrugated cylindrical\nsubstrates. The effective Hamiltonians for the liquid-gas interfaces\nfluctuating in the presence of such curved substrates are derived via the\nmean-field density functional theory. Their structure is compared with the\nHelfrich Hamiltonian which is parametrized by the bending and Gaussian rigidity\ncoefficients. For long-ranged interparticle interactions of van der Waals type\nthese coefficients turn out to be non-universal functions of interfacial\ncurvatures; their form varies from one interface to another. We discuss\nimplications of the structure of these functions on the effective Hamiltonian.",
        "positive": "On the interplay between activity, elasticity and liquid transport in\n  self-contractile biopolymer gels: Active gels play an important role in biology and in inspiring biomimetic\nactive materials, due to their ability to change shape, size and create their\nown morphology; the relevant mechanics behind these changes is driven by\nself-contraction and liquid flow. Here, we couple contraction and liquid flow\nwithin a nonlinear mechanical model of an active gel disc to discuss how\ncontraction dynamics inherits length scales which are typical of the liquid\nflow processes. The cylindrically symmetric model we present, which\nrecapitulate our previous theoretical modeling in its basic lines, reveals that\nwhen also liquid flow is taken into account, the aspect ratio of the disc is\nnot the only geometrical parameter which characterizes the contraction dynamics\nof the gel. The analyses we present provide important insights into the\ndependence of contraction dynamics on geometry and allow to make some progress\nin designing materials which can be adapted for different applications in soft\nrobotics."
    },
    {
        "anchor": "Universality in quasi-2D granular shock fronts above an intruder: We experimentally study quasi-2d dilute granular flow around intruders whose\nshape, size and relative impact speed are systematically varied. Direct\nmeasurement of the flow field reveals that three in-principle independent\nmeasurements of the non-uniformity of the flow field are in fact all linearly\nrelated: 1) granular temperature, 2) flow field divergence and 3) shear-strain\nrate. The shock front is defined as the local maxima in each of these\nmeasurements. The shape of the shock front is well described by an inverted\ncatenary and is driven by the formation of a dynamic arch during steady flow.\nWe find universality in the functional form of the shock front within the range\nof experimental values probed. Changing the intruder size, concavity and impact\nspeed only results in a scaling and shifting of the shock front. We\nindependently measure the horizontal lift force on the intruder and find that\nit can be understood as a result of the interplay between the shock profile and\nthe intruder shape.",
        "positive": "Fluctuations of the Casimir-like force between two membrane inclusions: Although Casimir forces are inseparable from their fluctuations, little is\nknown about these fluctuations in soft matter systems. We use the membrane\nstress tensor to study the fluctuations of the membrane-mediated Casimir-like\nforce. This method enables us to recover the Casimir force between two\ninclusions and to calculate its variance. We show that the Casimir force is\ndominated by its fluctuations. Furthermore, when the distance d between the\ninclusions is decreased from infinity, the variance of the Casimir force\ndecreases as -1/d^2. This distance dependence shares a common physical origin\nwith the Casimir force itself."
    },
    {
        "anchor": "Reply to \"Failure to replicate long-range tunable attractions in\n  colloidal system\": An arxiv paper, ref. [1] by Cao et al., claimed that the tunable attraction\nreported in our ref. [2] could not be detected. Ref. [1] was submitted to\nNature in Apr. 2016 as a Comment on our ref. [2]. Our reply in May 2016\nresponded to ref. [1] and was reviewed by the editor of Nature and an external\nreferee. Ref. [1] was rejected by Nature in Aug. 2016. We provide our reply,\nwhich answers all of the criticisms in ref. [1], in Appendix I. The main text\ncontains a brief reply to the main criticisms.",
        "positive": "The role of electrostriction on the stability of dielectric elastomer\n  actuators: In the field of soft dielectric elastomers, the notion electrostriction\nindicates the dependency of the permittivity on strain. The present paper is\naimed at investigating the effects of electrostriction onto the stability\nbehaviour of homogeneous electrically activated dielectric elastomer actuators.\nIn particular, three objectives are pursued and achieved: i) the description of\nthe phenomenon within the general nonlinear theory of electroelasticity; ii)\nthe application of the recently proposed theory of bifurcation for\nelectroelastic bodies in order to determine its role on the onset of\nelectromechanical and diffuse-mode instabilities in prestressed or prestretched\ndielectric layers; iii) the analysis of band-localization instability in\nhomogeneous dielectric elastomers. Results for a typical soft acrylic elastomer\nshow that electrostriction is responsible for an enhancement towards\ndiffuse-mode instability, while it represents a crucial property - necessarily\nto be taken into account - in order to provide a solution to the problem of\nelectromechanical band-localization, that can be interpreted as a possible\nreason of electric breakdown. A comparison between the buckling stresses of a\nmechanical compressed slab and the electrically activated counterpart concludes\nthe paper."
    },
    {
        "anchor": "General contact mechanics theory for randomly rough surfaces with\n  application to rubber friction: We generalize the Persson contact mechanics and rubber friction theory to the\ncase where both surfaces have surface roughness. The solids can be rigid,\nelastic or viscoelastic, and can be homogeneous or layered. We calculate the\ncontact area, the viscoelastic contribution to the friction force, and the\naverage interfacial separation as a function of the sliding speed and the\nnominal contact pressure. We illustrate the theory with numerical results for a\nrubber block sliding on a road surface. We find that with increasing sliding\nspeed, the influence of the roughness on the rubber block decreases, and for\ntypical sliding speeds involved in tire dynamics it can be neglected.",
        "positive": "Super-diffusion around the rigidity transition: Levy and the\n  Lilliputians: By analyzing the displacement statistics of an assembly of horizontally\nvibrated bidisperse frictional grains in the vicinity of the jamming transition\nexperimentally studied before, we establish that their superdiffusive motion is\na genuine Levy flight, but with `jump' size very small compared to the diameter\nof the grains. The vibration induces a broad distribution of jumps that are\nrandom in time, but correlated in space, and that can be interpreted as\nmicro-crack events at all scales. As the volume fraction departs from the\ncritical jamming density, this distribution is truncated at a smaller and\nsmaller jump size, inducing a crossover towards standard diffusive motion at\nlong times. This interpretation contrasts with the idea of temporally\npersistent, spatially correlated currents and raises new issues regarding the\nanalysis of the dynamics in terms of vibrational modes."
    },
    {
        "anchor": "Size Exponents of Branched Polymers/ Extension of the Isaacson-Lubensky\n  Formula and the Application to Lattice Trees: Branched polymers can be classified into two categories that obey the\ndifferent formulae: \\begin{equation} \\nu= \\begin{cases}\n\\hspace{1mm}\\displaystyle\\frac{2(1+\\nu_{0})}{d+2} & \\hspace{3mm}\\mbox{for\npolymers\nwith}\\hspace{2mm}\\displaystyle\\nu_{0}\\ge\\frac{1}{d+1}\\hspace{10mm}\\text{(I)}\\\\[3mm]\n\\hspace{5mm}2\\nu_{0}& \\hspace{3mm}\\mbox{for polymers\nwith}\\hspace{2mm}\\displaystyle\\nu_{0}\\le\\frac{1}{d+1}\\hspace{10mm}\\text{(II)}\n\\end{cases}\\notag \\end{equation} for the dilution limit in good solvents. The\ncategory II covers the exceptional polymers having fully expanded\nconfigurations. On the basis of these equalities, we discuss the size exponents\nof the nested architectures and the lattice trees. In particular, we compare\nour preceding result, $\\nu_{d=2}=1/2$, for the $z$=2 polymer having\n$\\nu_{0}=1/4$ with the numerical result, $\\nu_{d=2}\\doteq 0.64115$, for the\nlattice trees generated on the 2-dimensional lattice. Our conjecture is that\nwhile both the conclusions in polymer physics and condensed matter physics are\ncorrect, the discrepancy arises from the fact that the lattice trees are\nconstructed from less branched architectures than the branched polymers having\n$\\nu_{0} = 1/4$ in polymer physics. The present analysis suggests that the\n2-dimensional lattice trees are the mixture of isomers having the mean ideal\nsize exponent of $\\bar{\\nu}_{0}\\doteq0.32$.",
        "positive": "Anomalous Elasticity and Emergent Dipole Screening in Three-Dimensional\n  Amorphous Solids: In recent work, we developed a screening theory for describing the effect of\nplastic events in amorphous solids on its emergent mechanics. The suggested\ntheory uncovered an anomalous mechanical response of amorphous solids where\nplastic events collectively induce distributed dipoles that are analogous to\ndislocations in crystalline solids. The theory was tested against various\nmodels of amorphous solids in two-dimensions, including frictional and\nfriction-less granular media and numerical models of amorphous glass. Here we\nextend our theory to screening in three-dimensional amorphous solids and\npredict the existence of anomalous mechanics similar to the one observed in\ntwo-dimensional systems. We conclude by interpreting the mechanical response as\nthe formation of non-topological distributed dipoles that have no analogue in\nthe crystalline defects literature. Having in mind that the onset of dipole\nscreening is reminiscent of Kosterlitz-Thouless and Hexatic transitions, the\nfinding of dipole screening in three-dimensions is particularly novel."
    },
    {
        "anchor": "Primitive Chain Network Simulations of Entangled Melts of Symmetric and\n  Asymmetric Star Polymers in Uniaxial Elongational Flows: Ianniruberto and Marrucci developed a theory whereby entangled branched\npolymers behave like linear ones in fast elongational flows. In order to test\nsuch prediction, Huang et al. performed elongational measurements on star\npolymer melts, indeed revealing that, in fast flows, the elongational viscosity\nis insensitive to the molecular structure, provided the molecular weight of the\nbackbone is the same. Inspired by these studies, we here report on results\nobtained with multi-chain slip-link simulations for symmetric and asymmetric\nstar polymer melts, as well as calculations of the Rouse time of the examined\nbranched structures. The simulations semi-quantitatively reproduce the\nexperimental data if the Kuhn-segment orientation-induced reduction of friction\n(SORF) is accounted for. The observed insensitivity of the nonlinear\nelongational viscosity to the molecular structure for the same span molar mass\nmay be due to several factors. In the symmetric case, the calculated Rouse time\nof the star marginally differs from that of the linear molecule, so that\npossible differences in the observed stress fall within the experimental\nuncertainty. Secondly, it is possible that the flow-induced formation of hooked\nstar pairs makes the effective Rouse time of the aggregate even closer to that\nof the linear polymer because the friction center moves towards the branchpoint\nof the star molecule. In the asymmetric case, it is shown that the stress\ncontributed by the short arms is negligible with respect to that of the long\nones. However, such stress-reduction is balanced by a dilution effect whereby\nthe unstretched arms reduce SORF as they decrease the Kuhn-segment order\nparameter of the system. As a result of that dilution, the stress contributed\nby the backbone is larger. The two effects compensate one another so that the\noverall stress is virtually the same as the other architectures.",
        "positive": "Bridging particle deformability and collective response in soft solids: Soft, amorphous solids such as tissues, foams, and emulsions are composed of\ndeformable particles. However, the effect of single-particle deformability on\nthe collective behavior of soft solids is still poorly understood. We perform\nnumerical simulations of two-dimensional jammed packings of explicitly\ndeformable particles to study the mechanical response of model soft solids. We\nfind that jammed packings of deformable particles with excess shape degrees of\nfreedom possess low-frequency quartic vibrational modes that stabilize the\npackings even though they possess fewer interparticle contacts than the nominal\nisostatic value. Adding intra-particle constraints can rigidify the particles,\nbut these particles undergo a buckling transition and gain an effective shape\ndegree of freedom when their preferred perimeter is above a threshold value. We\nfind that the mechanical response of jammed packings of deformable particles\nwith shape degrees of freedom differs significantly from that of jammed\npackings of rigid-shape particles, which emphasizes the importance of particle\ndeformability in modelling soft solids."
    },
    {
        "anchor": "Multiple character of non-monotonic size-dependence for relaxation\n  dynamics in polymer-particle and binary mixtures: Adding plasticizers is a well-known procedure to reduce the glass transition\ntemperature in polymers. It has been recently shown that this effect shows a\nnon-monotonic dependence on the size of additive molecules [The Journal of\nChemical Physics 150 (2019) 024903]. In this work, we demonstrate that, as the\nsize of the additive molecules is changed at fixed concentration, multiple\nextrema emerge in the dependence of the system's relaxation time on the size\nratio. The effect occurs on all relevant length scales including single monomer\ndynamics, decay of Rouse modes and relaxation of the chain's end-to-end vector.\nA qualitatively similar trend is found within mode-coupling theoretical results\nfor a binary hard-sphere (HS) mixture. An interpretation of the effect in terms\nof local packing efficiency and coupling between the dynamics of minority and\nmajority species is provided.",
        "positive": "Cell nucleus as a microrheological probe to study the rheology of the\n  cytoskeleton: Mechanical properties of the cell are important biomarkers for probing its\narchitectural changes caused by cellular processes and/or pathologies. The\ndevelopment of microfluidic technologies have enabled measuring cell mechanics\nat high-throughput, so that mechanical phenotyping can be applied to large\nsamples in reasonable time-scales. These studies typically measure the\nstiffness of the cell as the only mechanical biomarker, and cannot disentangle\nthe rheological contribution of different structural components of the cell,\nincluding the cell cortex, the interior cytoplasm and its immersed cytoskeletal\nstructures, and the nucleus. Recent advancements in high-speed fluorescent\nimaging have enabled probing the deformations of the cell cortex, while also\ntracking different intracellular components in rates applicable to microfluidic\nplatforms. We present a novel method to decouple the mechanics of the cell\ncortex and the cytoplasm by analyzing the correlation between the cortical\ndeformations that are induced by external microfluidic flows, and the nucleus\ndisplacements induced by those cortical deformations; i.e. we use the nucleus\nas a high-throughput microrheological probe to study the rheology of the\ncytoplasm, independent of the cell cortex mechanics. To demonstrate the\napplicability of this method, we consider a proof of concept model consisting\nof a rigid spherical nucleus centered in a spherical cell. We obtain analytical\nexpressions for time-dependent nucleus velocity as a function of the cell\ndeformations, when the interior cytoplasm is modeled as a viscous,\nviscoelastic, porous and poroelastic materials, and demonstrate how the nucleus\nvelocity can be used to characterize the linear rheology of the cytoplasm over\na wide range of forces and time-scales/frequencies."
    },
    {
        "anchor": "On the colloidal stability of apolar nanoparticles: The role of particle\n  size and ligand shell structure: Being able to predict and tune the colloidal stability of nanoparticles is\nessential for a wide range of applications, yet our ability to do so is\ncurrently poor due to a lack of understanding of how they interact with one\nanother. Here, we show that the agglomeration of apolar particles is dominated\nby either the core or the ligand shell, depending on the particle size and\nmaterials. We do this by using Small-Angle X-ray Scattering and molecular\ndynamics simulations to characterize the interaction between hexadecanethiol\npassivated gold nanoparticles in decane solvent. For smaller particles, the\nagglomeration temperature and interparticle spacing are determined by ordering\nof the ligand shell into bundles of aligned ligands that attract one another\nand interlock. In contrast, the agglomeration of larger particles is driven by\nvan der Waals attraction between the gold cores, which eventually becomes\nstrong enough to compress the ligand shell. Our results provide a microscopic\ndescription of the forces that determine the colloidal stability of apolar\nnanoparticles and explain why classical colloid theory fails.",
        "positive": "Heat convection and radiation in flighted rotary kilns: A minimal model: We propose a minimal model aiming to describe heat transfer between particles\n(i.e. grains) and gases in a model of flighted rotary kilns. It considers a\nchannel in which a convective gas interacts with a granular suspension and a\ngranular bed. Despite its simplicity it captures the main experimental findings\nin the case of dilute suspension of heavy grains typical of what can be\nobserved in many industrial rotary kilns. Energy balance between each phase\ntakes into account the main heat transfer mechanisms between the transverse\ngranular motion and the convective gas. In the absence of radiation heat\ntransfer, the model predicts exponential variations of the temperatures\ncharacterized by a length which depends on the granular and gas heat flow rates\nas well as on the exchange areas. When radiation is taken into account, the\nmodel can be solved numerically. For this case, the temperature variations can\nbe fitted by stretched exponentials whose parameters are found to be\nindependent of the studied phases. Finally, an efficiency criterion is proposed\nto optimize the length of the system."
    },
    {
        "anchor": "A minimal-length approach unifies rigidity in under-constrained\n  materials: We present a novel approach to understand geometric-incompatibility-induced\nrigidity in under-constrained materials, including sub-isostatic 2D spring\nnetworks and 2D and 3D vertex models for dense biological tissues. We show that\nin all these models a geometric criterion, represented by a minimal length\n$\\bar\\ell_\\mathrm{min}$, determines the onset of prestresses and rigidity. This\nallows us to predict not only the correct scalings for the elastic material\nproperties, but also the precise {\\em magnitudes} for bulk modulus and shear\nmodulus discontinuities at the rigidity transition as well as the magnitude of\nthe Poynting effect. We also predict from first principles that the ratio of\nthe excess shear modulus to the shear stress should be inversely proportional\nto the critical strain with a prefactor of three, and propose that this factor\nof three is a general hallmark of geometrically induced rigidity in\nunder-constrained materials and could be used to distinguish this effect from\nnonlinear mechanics of single components in experiments. Lastly, our results\nmay lay important foundations for ways to estimate $\\bar\\ell_\\mathrm{min}$ from\nmeasurements of local geometric structure, and thus help develop methods to\ncharacterize large-scale mechanical properties from imaging data.",
        "positive": "Kinetics of polymer looping with macromolecular crowding: effects of\n  volume fraction and crowder size: The looping of polymers such as DNA is a fundamental process in the molecular\nbiology of living cells, whose interior is characterised by a high degree of\nmolecular crowding. We here investigate in detail the looping dynamics of\nflexible polymer chains in the presence of different degrees of crowding. From\nthe analysis of the looping-unlooping rates and the looping probabilities of\nthe chain ends we show that the presence of small crowders typically slow down\nthe chain dynamics but larger crowders may in fact facilitate the looping. We\nrationalise these non-trivial and often counterintuitive effects of the crowder\nsize onto the looping kinetics in terms of an effective solution viscosity and\nstandard excluded volume effects. Thus for small crowders the effect of an\nincreased viscosity dominates, while for big crowders we argue that confinement\neffects (caging) prevail. The tradeoff between both trends can thus result in\nthe impediment or facilitation of polymer looping, depending on the crowder\nsize. We also examine how the crowding volume fraction, chain length, and the\nattraction strength of the contact groups of the polymer chain affect the\nlooping kinetics and hairpin formation dynamics. Our results are relevant for\nDNA looping in the absence and presence of protein mediation, DNA hairpin\nformation, RNA folding, and the folding of polypeptide chains under\nbiologically relevant high-crowding conditions."
    },
    {
        "anchor": "Towards automated sampling of polymorph nucleation and free energies\n  with SGOOP and metadynamics: Understanding the driving forces behind the nucleation of different\npolymorphs is of great importance for material sciences and the pharmaceutical\nindustry. This includes understanding the reaction coordinate that governs the\nnucleation process as well as correctly calculating the relative free energies\nof different polymorphs. Here we demonstrate, for the prototypical case of urea\nnucleation from melt, how one can learn such a 1-dimensional reaction\ncoordinate as a function of pre-specified order parameters, and use it to\nperform efficient biased all-atom molecular dynamics simulations. The reaction\ncoordinate is learnt as a function of generic thermodynamic and structural\norder parameters using the \"Spectral Gap Optimization of Order Parameters\n(SGOOP)\" approach [P. Tiwary and B. J. Berne, Proc. Natl. Acad. Sci. (2016)],\nand is biased using well-tempered metadynamics simulations. The reaction\ncoordinate gives insight into the role played by different structural and\nthermodynamics order parameters, and the biased simulations obtain accurate\nrelative free energies for different polymorphs. This includes accurate\nprediction of the approximate pressure at which urea undergoes a phase\ntransition and one of the metastable polymorphs becomes the most stable\nconformation. We believe the ideas demonstrated in thus work will facilitate\nefficient sampling of nucleation in complex, generic systems.",
        "positive": "Pumping and mixing in active pores: We show both numerically and analytically that a chemically patterned active\npore can act as a micro/nano-pump for fluids, even if it is fore-aft symmetric.\nThis is possible due to a spontaneous symmetry breaking which occurs when\nadvection rather than diffusion is the dominant mechanism of solute transport.\nWe further demonstrate that, for pumping and tuning the flow rate, a\ncombination of geometrical and chemical inhomogeneities is required. For\ncertain parameter values, the flow is unsteady, and persistent oscillations\nwith a tunable frequency appear. Finally, we find that the flow may lose its\naxial symmetry and hence promotes mixing in the low Reynolds number regime."
    },
    {
        "anchor": "Spout States in the Selective Withdrawal System: In selective withdrawal, fluid is withdrawn through a nozzle suspended above\nthe flat interface separating two immiscible, density-separated fluids of\nviscosities $\\nu_{upper}$ and $\\nu_{lower} = \\lambda \\nu_{upper}$. At low\nwithdrawal rates, the interface gently deforms into a hump. At a transition\nwithdrawal rate, a spout of the lower fluid becomes entrained with the flow of\nthe upper one into the nozzle. When $\\lambda = 0.005$, the spouts at the\ntransition are very thin with features that are over an order of magnitude\nsmaller than any observed in the humps. When $\\lambda = 20$, there is an\nintricate pattern of hysteresis and a spout appears which is qualitatively\ndifferent from those seen at lower $\\lambda$. No corresponding qualitative\ndifference is seen in the hump shapes.",
        "positive": "Effective interactions between star polymers and colloidal particles: Using monomer-resolved Molecular Dynamics simulations and theoretical\narguments based on the radial dependence of the osmotic pressure in the\ninterior of a star, we systematically investigate the effective interactions\nbetween hard, colloidal particles and star polymers in a good solvent. The\nrelevant parameters are the size ratio q between the stars and the colloids, as\nwell as the number of polymeric arms f (functionality) attached to the common\ncenter of the star. By covering a wide range of q's ranging from zero (star\nagainst a flat wall) up to about 0.75, we establish analytical forms for the\nstar-colloid interaction which are in excellent agreement with simulation\nresults. A modified expression for the star-star interaction for low\nfunctionalities, f < 10 is also introduced."
    },
    {
        "anchor": "Inhomogeneous screening near a dielectric interface: Screening is one of the most important concepts in the study of charged\nsystems. Near a dielectric interface, the ion distribution in a salt solution\ncan be highly nonuniform. Here, we develop a theory that self-consistently\ntreats the inhomogeneous screening effects. At higher concentrations when the\nbulk Debye screening length is comparable to the Bjerrum length, the double\nlayer structure and interfacial properties are significantly affected by the\ninhomogeneous screening. In particular, the depletion zone is considerably\nwider than that predicted by the bulk screening approximation or the WKB\napproximation. For asymmetric salts, the inhomogeneous screening leads to\nenhanced charge separation and surface potential.",
        "positive": "Linear and nonlinear rheology of wormlike micelles: Several surfactant molecules self-assemble in solution to form long,\ncylindrical, flexible wormlike micelles. These micelles can be entangled with\neach other leading to viscoelastic phases. The rheological properties of such\nphases are very interesting and have been the subject of a large number of\nexperimental and theoretical studies in recent years. We shall report on our\nrecent work on the macrorheology, microrheology and nonlinear flow behaviour of\ndilute aqueous solutions of a surfactant CTAT (Cetyltrimethylammonium\nTosilate). This system forms elongated micelles and exhibits strong\nviscoelasticity at low concentrations ($\\sim$ 0.9 wt%) without the addition of\nelectrolytes. Microrheology measurements of $G(\\omega)$ have been done using\ndiffusing wave spectroscopy which will be compared with the conventional\nfrequency sweep measurements done using a cone and plate rheometer. The second\npart of the paper deals with the nonlinear rheology where the measured shear\nstress $\\sigma$ is a nonmonotonic function of the shear rate $\\dot{\\gamma}$. In\nstress-controlled experiments, the shear stress shows a plateau for\n$\\dot{\\gamma}$ larger than some critical strain rate, similar to the earlier\nreports on CPyCl/NaSal system. Cates et al have proposed that the plateau is a\nsignature of mechanical instability in the form of shear bands. We have carried\nout extensive experiments under controlled strain rate conditions, to study the\ntime-dependence of shear stress. The measured time series of shear stress has\nbeen analysed in terms of correlation integrals and Lyapunov exponents to show\nunambiguously that the behaviour is typical of low dimensional dynamical\nsystems."
    },
    {
        "anchor": "Polarity switch of PMMA powder transported through a PMMA duct: During pneumatic conveying, powder electrifies rapidly due to the high flow\nvelocities. In our experiments, the particles even charge if the conveying duct\nis made of the same material, which might be caused by triboelectrification\nbetween two asymmetric contact surfaces. Surprisingly, we found the airflow\nrate to determine the polarity of the overall powder charge. This study\ninvestigates the charging of microscale PMMA particles in turbulent flows\npassing through a square PMMA duct. The particles are spherical and\nmonodisperse. A Faraday at the duct outlet measured the total charge of the\nparticles. At low flow velocities, the particles charged negatively after\npassing through the duct. However, the powder's overall charge switched to a\npositive polarity when increasing the flow velocity.",
        "positive": "Self-consistent mode-coupling theory for the viscosity of rod-like\n  polyelectrolyte solutions: A self-consistent mode-coupling theory is presented for the viscosity of\nsolutions of charged rod-like polymers. The static structure factor used in the\ntheory is obtained from polymer integral equation theory; the Debye-H\\\"{u}ckel\napproximation is inadequate even at low concentrations. The theory predicts a\nnon-monotonic dependence of the reduced excess viscosity, $\\eta_R$, on\nconcentration from the behaviour of the static structure factor in\npolyelectrolyte solutions. The theory predicts that the peak in $\\eta_R$ occurs\nat concentrations slightly lower than the overlap threshold concentration,\n$c^\\ast$. The peak height increases dramatically with increasing molecular\nweight and decreases with increased concentrations of added salt. The position\nof the peak, as a function of concentration divided by $c^\\ast$ is independent\nof salt concentration or molecular weight. The predictions can be tested\nexperimentally."
    },
    {
        "anchor": "Condensation transition in DNA-polyaminoamide dendrimer fibers studied\n  using optical tweezers: When mixed together, DNA and polyaminoamide (PAMAM) dendrimers form fibers\nthat condense into a compact structure. We use optical tweezers to pull\ncondensed fibers and investigate the decondensation transition by measuring\nforce-extension curves (FECs). A characteristic plateau force (around 10 pN)\nand hysteresis between the pulling and relaxation cycles are observed for\ndifferent dendrimer sizes, indicating the existence of a first-order transition\nbetween two phases (condensed and extended) of the fiber. The fact that we can\nreproduce the same FECs in the absence of additional dendrimers in the buffer\nmedium indicates that dendrimers remain irreversibly bound to the DNA backbone.\nUpon salt variation FECs change noticeably confirming that electrostatic forces\ndrive the condensation transition. Finally, we propose a simple model for the\ndecondensing transition that qualitatively reproduces the FECs and which is\nconfirmed by AFM images.",
        "positive": "Influence of surface roughness on superhydrophobicity: Superhydrophobic surfaces, with liquid contact angle theta greater than 150\ndegree, have important practical applications ranging from self-cleaning window\nglasses, paints, and fabrics to low-friction surfaces. Many biological\nsurfaces, such as the lotus leaf, have hierarchically structured surface\nroughness which is optimized for superhydrophobicity through natural selection.\nHere we present a molecular dynamics study of liquid droplets in contact with\nself-affine fractal surfaces. Our results indicate that the contact angle for\nnanodroplets depends strongly on the root-mean-square surface roughness\namplitude but is nearly independent of the fractal dimension D_f of the\nsurface."
    },
    {
        "anchor": "Quantum non-demolition measurements using Bose-Einstein condensates: We study possible scenarios for quantum non-demolition measurements using\nBose-Einstein condensates. We show that the interactions between condensate\natoms makes it possible to measure the atom number with minimal back action on\nthe system. This is an example of atomic nonlinear optics that has significant\nimplications in the quantum state preparation of the Bose condensates.",
        "positive": "Wrapping Transition and Wrapping-Mediated Interactions for Discrete\n  Binding along an Elastic Filament: An Exact Solution: The wrapping equilibria of one and two adsorbing cylinders are studied along\na semi-flexible filament (polymer) due to the interplay between elastic\nrigidity and short-range adhesive energy between the cylinder and the filament.\nWe show that statistical mechanics of the system can be solved exactly using a\npath integral formalism which gives access to the full effect of thermal\nfluctuations, going thus beyond the usual Gaussian approximations which take\ninto account only the contributions from the minimal energy configuration and\nsmall fluctuations about this minimal energy solution. We obtain the free\nenergy of the wrapping-unwrapping transition of the filament around the\ncylinders as well as the effective interaction between two wrapped cylinders\ndue to thermal fluctuations of the elastic filament. A change of entropy due to\nwrapping of the filament around the adsorbing cylinders as they move closer\ntogether is identified as an additional source of interactions between them.\nSuch entropic wrapping effects should be distinguished from the usual entropic\nconfiguration effects in semi-flexible polymers. Our results may be applicable\nto the problem of adsorption of proteins as well as synthetic nano-particles on\nsemi-flexible polymers such as DNA."
    },
    {
        "anchor": "Coalescence of sessile polymer droplets: A molecular dynamics study: Droplet coalescence is ubiquitous in nature and the same time key to various\ntechnologies, such as inkjet printing. Here, we report on the coalescence of\npolymer droplets with different chain lengths coalescing on substrates of\ndifferent wettability. By means of molecular dynamics simulations of a\ncoarse-grained model, it is found that the rate of bridge growth is higher in\nthe case of droplets with smaller contact angles (more wettable substrates) and\ndecreases with the increase of the chain length of the polymers. Different\nbehavior has also been identified in the dynamics of the approach of the two\ndroplets during coalescence with the substrate wettability playing a more\nimportant role compared to the chain length of the polymers. While the dynamics\nof the droplet are greatly affected by the latter parameters, the density\nprofile and flow patterns remain the same for the different cases. Thus, we\nanticipate that our work provides further insights into the coalescence of\nliquid polymer droplets on solid substrates with implications for relevant\ntechnologies.",
        "positive": "Minimal numerical ingredients describe chemical microswimmers's 3D\n  motion: The underlying mechanisms and physics of catalytic Janus microswimmers is\nhighly complex, requiring details of the associated phoretic fields and the\nphysiochemical properties of catalyst, particle, boundaries, and the fuel used.\nTherefore, developing a minimal (and more general) model capable of capturing\nthe overall dynamics of these autonomous particles is highly desirable. In the\npresented work, we demonstrate that a coarse-grained dissipative\nparticle-hydrodynamics model is capable of describing the behaviour of various\nchemical microswimmer systems. Specifically, we show how a competing balance\nbetween hydrodynamic interactions experienced by a squirmer in the presence of\na substrate, gravity, and mass and shape asymmetries can reproduce a range of\ndynamics seen in different experimental systems. We hope that our general model\nwill inspire further synthetic work where various modes of swimmer motion can\nbe encoded via shape and mass during fabrication, helping to realise the still\noutstanding goal of microswimmers capable of complex 3-D behaviour"
    },
    {
        "anchor": "The spontaneous emergence of ordered phases in crumpled sheets: X-ray tomography is performed to acquire 3D images of crumpled aluminum\nfoils. We develop an algorithm to trace out the labyrinthian paths in the three\nperpendicular cross sections of the data matrices. The tangent-tangent\ncorrelation function along each path is found to decay exponentially with an\neffective persistence length that shortens as the crumpled ball becomes more\ncompact. In the mean time, we observed ordered domains near the crust, similar\nto the lamellae phase mixed by the amorphous portion in lyotropic liquid\ncrystals. The size and density of these domains grow with further compaction,\nand their orientation favors either perpendicular or parallel to the radial\ndirection. Ordering is also identified near the core with an arbitrary\norientation, exemplary of the spontaneous symmetry breaking.",
        "positive": "Multi-component generalized mode-coupling theory: Predicting dynamics\n  from structure in glassy mixtures: The emergence of glassy dynamics and the glass transition in dense disordered\nsystems is still not fully understood theoretically. Mode-coupling theory (MCT)\nhas shown to be effective in describing some of the non-trivial features of\nglass formation, but it cannot explain the full glassy phenomenology due to the\nstrong approximations on which it is based. Generalized mode-coupling theory\n(GMCT) is a hierarchical extension of the theory, which is able to outclass MCT\nby carefully describing the dynamics of higher order correlations in its\ngeneralized framework. Unfortunately, the theory has so far only been developed\nfor single component systems and as a result works poorly for highly\npolydisperse materials. In this paper, we solve this problem by developing GMCT\nfor multi-component systems. We use it to predict the glassy dynamics of the\nbinary Kob-Andersen Lennard-Jones mixture, as well as its purely repulsive\nWeeks-Chandler-Andersen analogue. Our results show that each additional level\nof the GMCT hierarchy gradually improves the predictive power of GMCT beyond\nits previous limit. This implies that our theory is able to harvest more\ninformation from the static correlations, thus being able to better understand\nthe role of attraction in supercooled liquids from a first-principles\nperspective."
    },
    {
        "anchor": "Nanoemulsion stability above the critical micelle concentration: A\n  contest between solubilization, flocculation and Krafft precipitation: The relative importance of micelle solubilization and Krafft temperature on\nthe appraisal of the flocculation rate is studied using a dodecane-in-water\nnanoemulsion as a model system. In 0.5 mM solutions of sodium dodecylsulfate\n(SDS), neither the critical micelle concentration (CMC) nor the Krafft point of\nthe surfactant are attained between 300 and 700 mM NaCl and 20 < T < 25\n{\\deg}C. Hence, the addition of salt to a SDS-stabilized nanoemulsion only\ninduces aggregation. Conversely, a surfactant concentration of 7.5 mM SDS\npromotes micelle solubilization or crystal precipitation depending on the\nphysicochemical conditions. Solubilization decreases the absorbance of the\nsystem while flocculation and Krafft precipitation increase it. In this paper,\nthe actual variation of the absorbance above the CMC was followed during five\nminutes for 300, 500 and 700 mM NaCl. The initial 60-second changes were used\nto determine apparent aggregation rates. The solubilization capacity of the\nsystems was appraised using plots of absorbance vs. volume fraction of oil for\ndifferent salt concentrations and observation times. The variation of the\nKrafft point as a function of the salt concentration was also studied using\nsurfactant solutions and emulsions. Finally, small-scale simulations accounting\nfor micelle solubilization were implemented in order to advance in the\ncomprehension of the problem.",
        "positive": "Modeling of Magnetostriction of Soft Elastomer: Small magnetic particles placed in a relatively soft polymer (with elastic\nmodulus E ~ 10-100 kPa) are magnetically soft elastomers. The external magnetic\nfield acts on each particle which leads to microscopic deformation of the\nmaterial and consequently to changing of its shape - magnetostriction. For\npurposes of studying of magnetostriction the model of movable cellular automata\n(MCA), in which a real heterogeneous material is an ensemble of interacting\nelements of finite size - automata, is used. It is supposed to be that the\nmotion of each automata can be described by Newton's Second law. The force\nacting on the i-th automata consists of the following components:\nvolume-dependent force acting on the automata i which is caused by pressure\nfrom the surrounding automata; force of an external magnetic field acting on\nthe i-th automata with some magnetic moment; and normal and tangential\ninteraction force between a pair of i and j automata. This approach was used\nfor modeling of magnetostriction elastomer."
    },
    {
        "anchor": "Jamming by growth: Growth in confined spaces can drive cellular populations through a jamming\ntransition from a fluid-like state to a solid-like state. Experiments have\nfound that jammed budding yeast populations can build up extreme compressive\npressures (over 1MPa), which in turn feed back onto cellular physiology by\nslowing or even stalling cell growth. Using extensive numerical simulations, we\ninvestigate how this feedback impacts the mechanical properties of model jammed\ncellular populations. We find that feedback directs growth toward\npoorly-coordinated regions, resulting in an excess number of cell-cell contacts\nthat rigidify cell packings. Cell packings posses anomalously large shear and\nbulk moduli that depend sensitively on the strength of feedback. These results\ndemonstrate that mechanical feedback on the single-cell level is a simple\nmechanism by which living systems can tune their population-level mechanical\nproperties.",
        "positive": "Acceleration of the condensational growth of water droplets in an\n  external electric field: The condensational growth of spherical water microdroplets is studied in a\nlaboratory setup and with a mathematical model. In the experiment, droplet\nclusters are kept in a freely levitated state within an upward-oriented flow of\nwater vapor. In the presence of an electrostatic field of 1.5 * 10^5 V / m,\ndroplet growth is accelerated by factors 1.5 to 2.0 as compared to conditions\nwithout any external electric field. Presumably water molecules in the ambient\nair are accelerated through the presence of the electric field. A kinetic model\nto predict the acceleration of condensational growth confirms this hypothesis\nto be feasible. The droplets themselves are polarized so that the deposition of\nsteam molecules is facilitated in the electric field. The simplifications and\nlimitations of the model are discussed."
    },
    {
        "anchor": "A full-chain tube-based constitutive model for living linear polymers: We present a new strategy for introducing population balances into full-chain\nconstitutive models of living polymers with linear chain architectures. We\nprovide equations to describe a range of stress relaxation processes covering\nboth unentangled systems (Rouse-like motion) and well entangled systems\n(reptation, contour length fluctuations, chain retraction, and constraint\nrelease). Special attention is given to the solutions that emerge when the\n'breaking time' of the chain becomes fast compared to various stress relaxation\nprocesses. In these 'fast breaking' limits, we reproduce previously known\nresults (with some corrections) and also present new results for nonlinear\nstress relaxation dynamics. Our analysis culminates with a fully developed\nconstitutive model for the fast breaking regime in which stress relaxation is\ndominated by contour length fluctuations. Linear and nonlinear rheology\npredictions of the model are presented and discussed.",
        "positive": "Modeling capsid self-assembly: Design and analysis: A series of simulations aimed at elucidating the self-assembly dynamics of\nspherical virus capsids is described. This little-understood phenomenon is a\nfascinating example of the complex processes that occur in the simplest of\norganisms. The fact that different viruses adopt similar structural forms is an\nindication of a common underlying design, motivating the use of simplified,\nlow-resolution models in exploring the assembly process. Several versions of a\nmolecular dynamics approach are described. Polyhedral shells of different sizes\nare involved, the assembly pathways are either irreversible or reversible, and\nan explicit solvent is optionally included. Model design, simulation\nmethodology and analysis techniques are discussed. The analysis focuses on the\ngrowth pathways and the nature of the intermediate states, properties that are\nhard to access experimentally. Among the key observations are that efficient\ngrowth proceeds by means of a cascade of highly reversible stages, and that\nwhile there are a large variety of possible partial assemblies, only a\nrelatively small number of strongly bonded configurations are actually\nencountered."
    },
    {
        "anchor": "Hard core-soft shell particles near repulsive interfaces: interplay\n  between adsorption, aggregation and diffusion: The behavior of colloidal particles with a hard core and a soft shell has\nattracted the attention for researchers in the physical-chemistry interface not\nonly due the large number of applications, but due the unique properties of\nthese systems in bulk and at interfaces. The adsorption at the boundary of two\nphases can provide information about the molecular arrangement. In this way, we\nperform Langevin Dynamics simulations of polymer-grafted nanoparticles. We\nemployed a recently obtained core-softened potential to analyze the relation\nbetween adsorption, structure and dynamic properties of the nanoparticles near\na solid repulsive surface. Two cases were considered: flat or structured walls.\nAt low temperatures, a maxima is observed in the adsorption. It is related to a\nfluid to clusters transition and with a minima in the contact layer diffusion -\nand is explained by the competition between the scales in the core-softened\ninteraction. Due the long range repulsion, the particles stay at the distance\ncorrespondent to this length scale at low densities, and overcome the repulsive\nbarrier as the packing increases, However, increasing the temperature, the gain\nin kinetic energy allows the colloids to overcome the long range repulsion\nbarrier even at low densities. As consequence, there is no competition and no\nmaxima was observed in the adsorption.",
        "positive": "Effective Potential for Cellular Size Control: For various species of biological cells, experimental observations indicate\nthe existence of universal distributions of the cellular size, scaling\nrelations between the cell-size moments and simple rules for the cell-size\ncontrol. We address a class of models for the control of cell division, and\npresent the steady state distributions. By introducing concepts such as\neffective force and potential, we are able to address the appearance of scaling\ncollapse of different distributions and the connection between various moments\nof the cell-size. Our approach allows us to derive strict bounds which a\npotential cell-size control scenario must meet in order to yield a steady state\ndistribution. The so-called \"adder\" model for cell-size control exhibits the\nweakest control that still enables the existence of stable size distribution, a\nfact that might explain the relative \"popularity\" of this scenario for\ndifferent cells."
    },
    {
        "anchor": "Bacterial chromosome organization II: few special cross-links, cell\n  confinement, and molecular crowders play the pivotal roles: Using a bead-spring model of bacterial DNA polymers of {\\em C. crescentus}\nand {\\em E. coli} we show that just $33$ and $38$ effective cross-links at\nspecial positions along the chain contour of the DNA can lead to the\nlarge-scale organization of the DNA polymer, where confinement effects of the\ncell walls play a key role in the organization. The positions of the $33$\ncross-links along the chain contour are chosen from the contact map data of\n{\\em C. crescentus}. We represent $1000$ base pairs as a coarse-grained monomer\nin our bead-spring flexible ring polymer model of the DNA. Thus a $4017$ beads\non a flexible ring polymer represents the {\\em C. crescentus} DNA with $4017$\nkilo-base pairs. Choosing suitable parameters from our preceding study, we also\nincorporate the role of molecular crowders and the ability of the chain to\nrelease topological constraints. We validate our prediction of the organization\nof the {\\em C. crescentus} with available experimental contact map data and\nalso give a prediction of the approximate positions of different segments\nwithin the cell in 3D. For the {\\em E. coli} chromosome with $4.6$ million base\npairs, we need around $38$ effective cross-links with cylindrical confinement\nto organize the chromosome. We also predict the 3D organization of the {\\em E.\ncoli} chromosome segments within the cylinder which represents the cell wall.",
        "positive": "Controlling drop size and polydispersity using chemically patterned\n  surfaces: We explore numerically the feasibility of using chemical patterning to\ncontrol the size and polydispersity of micron-scale drops. The simulations\nsuggest that it is possible to sort drops by size or wetting properties by\nusing an array of hydrophilic stripes of different widths. We also demonstrate\nthat monodisperse drops can be generated by exploiting the pinning of a drop on\na hydrophilic stripe. Our results follow from using a lattice Boltzmann\nalgorithm to solve the hydrodynamic equations of motion of the drops and\ndemonstrate the applicability of this approach as a design tool for micofluidic\ndevices with chemically patterned surfaces."
    },
    {
        "anchor": "Scaling Laws for the Slip Velocity in Dense Granular Flows: In this Letter, the 2-dimensional dense flow of polygonal particles on an\nincline with a flat frictional inferior boundary is analyzed by means of\ncontact dynamics discrete element simulations, in order to develop boundary\nconditions for continuum models of dense granular flows. We show the evidence\nthat the global slip phenomenon deviates significantly from simple sliding: a\nfinite slip velocity is generally found for shear forces lower than the sliding\nthreshold for particle-wall contacts. We determined simple scaling laws for the\ndependence of the slip velocity on shear rate, normal and shear stresses, and\nmaterial parameters.The importance of a correct determination of the slip at\nthe base of the incline, which is crucial for the calculation of flow rates, is\ndiscussed in relation to natural flows.",
        "positive": "Theoretical modelling of Langmuir monolayers: We study coarse grained, continuum models for Langmuir monolayers by self\nconsistent field theory and by Monte Carlo simulations. Amphiphilic molecules\nare represented by stiff chains of monomers with one end grafted to a planar\nsurface. In particular, we discuss the origin of successive fluid-fluid\ntransitions, the possible origin of tilt order and the factors which determine\nthe direction of tilt."
    },
    {
        "anchor": "Structural Arrangements of Polymers Adsorbed at Nanostrings: We study ground states of a hybrid system consisting of a polymer and an\nattractive nanowire by means of computer simulations. Depending on structural\nand energetic properties of the substrate, we find different adsorbed polymer\nconformations, amongst which are spherical droplets attached to the wire and\nmonolayer tubes surrounding it. We construct the complete conformational phase\ndiagram and analyze in more detail particularly interesting polymer-tube\nconformations.",
        "positive": "Entropy Production Rate is Maximized in Non-Contractile Actomyosin: The actin cytoskeleton is an active semi-flexible polymer network whose\nnon-equilibrium properties coordinate both stable and contractile behaviors to\nmaintain or change cell shape. While myosin motors drive the actin cytoskeleton\nout-of-equilibrium, the role of myosin-driven active stresses in the\naccumulation and dissipation of mechanical energy is unclear. To investigate\nthis, we synthesize an actomyosin material in vitro whose active stress content\ncan tune the network from stable to contractile. Each increment in activity\ndetermines a characteristic spectrum of actin filament fluctuations which is\nused to calculate the total mechanical work and the production of entropy in\nthe material. We find that the balance of work and entropy does not increase\nmonotonically and, surprisingly, the entropy production rate is maximized in\nthe non-contractile, stable state. Our study provides evidence that the origins\nof system entropy production and activity-dependent dissipation arise from\ndisorder in the molecular interactions between actin and myosin"
    },
    {
        "anchor": "Liquid-Gas phase transition in Bose-Einstein Condensates: We study the effects of a repulsive three-body interaction on a system of\ntrapped ultra-cold atoms in a Bose-Einstein condensed state. The corresponding\n$s-$wave non-linear Schr\\\"{o}dinger equation is solved numerically and also by\na variational approach. A first-order liquid-gas phase transition is observed\nfor the condensed state up to a critical strength of the effective three-body\nforce.",
        "positive": "Buckling Thin Disks and Ribbons with Non-Euclidean Metrics: I consider the problem of a thin membrane on which a metric has been\nprescribed, for example by lithographically controlling the local swelling\nproperties of a polymer thin film. While any amount of swelling can be\naccommodated locally, geometry prohibits the existence of a global strain-free\nconfiguration. To study this geometrical frustration, I introduce a\nperturbative approach. I compute the optimal shape of an annular, thin ribbon\nas a function of its width. The topological constraint of closing the ribbon\ndetermines a relationship between the mean curvature and number of wrinkles\nthat prevents a complete relaxation of the compression strain induced by\nswelling and buckles the ribbon out of the plane. These results are then\napplied to thin, buckled disks, where the expansion works surprisingly well. I\nidentify a critical radius above which the disk in-plane strain cannot be\nrelaxed completely."
    },
    {
        "anchor": "Shear Thickening in Polymer Stabilized Colloidal Suspensions: This paper adopts a previously developed activation model of shear\nthickening, published by the authors, to sterically stabilized colloidal\nsuspensions. When particles arranged along the compression axis of a sheared\nsuspension, they may overcome the repulsive interaction and form hydroclusters\nassociated with shear thickening. Taking advantage of the total interaction\npotential of polymeric brush coating and van der Waals attraction, the\napplicability of the activation model is shown within the validity range of a\ncontinuum theory. For the comparison with an extensive experimental\ninvestigation, where some parameters are not available, the onset of shear\nthickening can be predicted with realistic assumptions of the model parameters.",
        "positive": "Polarizability of microemulsion droplets: Spheroidal fluid droplets immersed in another fluid and thermally fluctuating\nin the shape are considered. The polarizability of the droplet is evaluated up\nto the second order in the fluctuation amplitudes and also the previous\nfirst-order calculations from the literature are corrected. The correlation\nfunctions of the polarizability tensor components are found and used to\ndescribe the polarized and depolarized scattering of light, and the Kerr effect\non microemulsions in the limit of small concentration of the droplets. An\nalternative simple derivation of the Kerr constant is also given assuming that\nthe droplet in a weak electric field becomes a prolate ellipsoid. We consider\nboth the case when the thickness of the surface layer is neglected and when the\ndroplet is covered by a layer of nonzero thickness. The result differs\nsignificantly from that used in the literature to describe the Kerr-effect\nmeasurements on droplet microemulsions. Due to the difference the bending\nrigidity constant of the layer should be increased about two times in\ncomparison with the value found in the original experiments."
    },
    {
        "anchor": "Numerical study of drying process and columnar fracture process in\n  granules-water mixtures: The formation of three-dimensional prismatic cracks in the drying process of\nstarch-water mixtures is investigated numerically. We assume that the mixture\nis an elastic porous medium which possesses a stress field and a water content\nfield. The evolution of both fields are represented by a spring network and a\nphenomenological model with the water potential, respectively. We find that the\nwater content distribution has a propagating front which is not explained by a\nsimple diffusion process. The prismatic structure of cracks driven by the water\ncontent field is observed. The depth dependence and the coarsening process of\nthe columnar structure are also studied. The particle diameter dependence of\nthe scale of the columns and the effect of the crack networks on the dynamics\nof the water content field are also discussed.",
        "positive": "Skinny emulsions take on granular matter: Our understanding of the structural features of foams and emulsions has\nadvanced significantly over the last 20 years. However, with a search for\n\"super-stable\" liquid dispersions, foam and emulsion science employs\nincreasingly complex formulations which create solid-like visco-elastic layers\nat the bubble/drop surfaces. These lead to elastic, adhesive and frictional\nforces between bubbles/drops, impacting strongly how they pack and deform\nagainst each other, asking for an adaptation of the currently available\nstructural description. The possibility to modify systematically the\ninterfacial properties makes these dispersions ideal systems for the\nexploration of soft granular materials with complex interactions.\n  We present here a first systematic analysis of the structural features of\nsuch a system using a model silicone emulsion containing millimetre-sized\npolyethylene glycol drops (PEG). Solid-like drop surfaces are obtained by\npolymeric cross-linking reactions at the PEG-silicone interface. Using a novel\ndroplet-micromanipulator, we highlight the presence of elastic, adhesive and\nfrictional interactions between two drops. We then provide for the first time a\nfull tomographic analysis of the structural features of these emulsions. An\nin-depth analysis of the angle of repose, local volume fraction distributions,\npair correlation functions and the drop deformations for different skin\nformulations allow us to put in evidence the striking difference with\n\"ordinary\" emulsions having fluid-like drop surfaces. While strong analogies\nwith frictional hard-sphere systems can be drawn, these systems display a set\nof unique features due to the high deformability of the drops which await\nsystematic exploration."
    },
    {
        "anchor": "Hydrodynamics of polymers in an active bath: The conformational and dynamical properties of active polymers in solution\nare determined by the nature of the activity, and the behavior of polymers with\nself-propelled, active Brownian particle-type monomers differs qualitatively\nfrom that of polymers with monomers driven externally by colored noise forces.\nWe present simulation and theoretical results for polymers in solution in the\npresence of external active noise. In simulations, a semiflexible bead-spring\nchain is considered, in analytical calculations, a continuous linear wormlike\nchain. Activity is taken into account by independent monomer/site velocities,\nwith orientations changing in a diffusive manner. In simulations, hydrodynamic\ninteractions (HI) are taken into account by the Rotne-Prager-Yamakawa tensor,\nor by an implementation of the active polymer in the multiparticle collision\ndynamics approach for fluids. To arrive at an analytical solution, the\npreaveraged Oseen tensor is employed. The active process implies a dependence\nof the stationary-state properties on HI via polymer relaxation times. With\nincreasing activity, HI lead to an enhanced swelling of flexible polymers, and\nthe conformational properties differ substantially from those of polymers with\nself-propelled monomers in presence of HI or free-draining polymers. The\npolymer mean square displacement is enhanced by HI. Over a wide range of time\nscales, hydrodynamics leads to a subdiffusive regime of the site mean square\ndisplacement for flexible active polymers, with an exponent of (5/7), larger\nthan that of the Rouse (1/2) and Zimm (2/3) models of passive polymers.",
        "positive": "Correlation of plastic events with local structure in jammed packings\n  across spatial dimensions: In jammed packings, it is usually thought that local structure only plays a\nsignificant role in specific regimes. The standard deviation of the relative\nexcess coordination, $\\sigma_Z/ Z_\\mathrm{c}$, decays like $1/\\sqrt{d}$, so\nthat local structure should play no role in high spatial dimensions.\nFurthermore, in any fixed dimension $d \\geq 2$, there are diverging length\nscales as the pressure vanishes approaching the unjamming transition, again\nsuggesting that local structure should not be sufficient to describe response.\nHere we challenge the assumption that local structure does not matter in these\ncases. In simulations of jammed packings under athermal, quasistatic shear, we\nuse machine learning to identify a local structural variable, softness, that\ncorrelates with rearrangements in dimensions $d=2$ to $d=5$. We find that\nsoftness - and even just the coordination number $Z$ - are quite predictive of\nrearrangements over a wide range of pressures, all the way down to unjamming,\nin all $d$ studied. This result provides direct evidence that local structure\ncan play a role in higher spatial dimensions."
    },
    {
        "anchor": "How do Cicadas Emerge Together? Thermophysical Aspects of Their\n  Collective Decision-Making: Certain periodical cicadas exhibit life cycles with durations of 13 or 17\nyears, and it is now generally accepted that such large prime numbers arise\nevolutionarily to avoid synchrony with predators. Less well explored is the\nquestion of how, in the face of intrinsic biological and environmental noise,\ninsects within a brood emerge together in large successive swarms from\nunderground during springtime warming. Here we consider the decision-making\nprocess of underground cicada nymphs experiencing random but\nspatially-correlated thermal microclimates like those in nature. Introducing\nshort-range communication between insects leads to a model of consensus\nbuilding that maps on to the statistical physics of an Ising model with a\nquenched, spatially correlated random magnetic field and annealed site\ndilution, which displays the kinds of collective swarms seen in nature.",
        "positive": "Phase diagram of dilute polyelectrolytes: Collapse and redissolution by\n  association of counterions and coions: Dilute solutions of strongly charged polymer electrolytes undergo, upon\naddition of multivaltent salt to the solutions, a phase transition from\nextended conformations to collapsed or bundled ones. Upon further addition of\nsalt they experience a second transition, a redissolution back into extended\nconformations. This paper presents a theoretical study of the structure and\nproperties of the phase diagram of these solutions. On the basis of simple\nphenomenological observations a schematic phase diagram is constructed that\nallows a simple and explicit determination of the direction of the tie lines\nwithin the coexistence region. The actual shape of the coexistence boundary is\ndetermined by means of a model mean free energy functional that explicitly\nincludes the possibility of association of both counterions and coions to the\nelectrolyte. It is found that it is possible to redissolve the electrolytes\ninto conformations where the bare charge of the electrolyte is overcompensated\nby the counterions but, due to the associated coions, can have either sign of\ntotal effective charge. When coion association is possible, the redissolution\napproximately coincides with the reassociation of the coions and counterions in\nthe bulk of the solution."
    },
    {
        "anchor": "Spinodal fractionation in a polydisperse square well fluid: Using Kinetic Monte Carlo simulation, we model gas-liquid spinodal\ndecomposition in a size-polydisperse square well fluid, representing a\n'near-monodisperse' colloidal dispersion. We find that fractionation (demixing)\nof particle sizes between the phases begins asserting itself shortly after the\nonset of phase ordering. Strikingly, the direction of size fractionation can be\nreversed by a seemingly trivial choice between two inter-particle potentials\nwhich, in the monodisperse case, are identical -- we rationalise this in terms\nof a perturbative, equilibrium theory of polydispersity. Furthermore, our\nquantitative results show that Kinetic Monte Carlo simulation can provide\ndetailed insight into the role of fractionation in real colloidal systems.",
        "positive": "Intrinsic structure perspective for MIPS interfaces in two dimensional\n  systems of Active Brownian Particles: Suspensions of Active Brownian Particles (ABP) undergo motility induced phase\nseparation (MIPS) over a wide range of mean density and activity strength [1],\neven in the absence of an explicit attraction. Negative values of the\nmechanical surface tension have been reported, from the total forces across the\ninterface, while the stable fluctuations of the interfacial line would be\ninterpreted as a positive capillary surface tension [2], while in equilibrium\nliquid surfaces these two magnitudes are equal. We present here the analysis of\n2D-ABP interfaces in terms of the intrinsic density and force profiles,\ncalculated with the particle distance to the instantaneous interfacial line.\nOur results provide a new insight in the origin of the MIPS from the local\nrectification of the random active force on the particles near the interface.\nAs it had been pointed, that effect acts as an external potential [3] that\nproduces a pressure gradient across the interface, so that the mechanical\nsurface tension of the MIPS cannot be described as that of equilibrium\ncoexisting phases; but our analysis shows that most of that effect comes from\nthe tightly caged particles at the dense (inner) side of the MIPS interface,\nrather than from the free moving particles at the outer side that collide with\nthe dense cluster. Moreover, a clear correlation appears between the decay of\nthe hexatic order parameter at the dense slab and the end of the MIPS as the\nstrength of the active force is lowered. We test that with the strong active\nforces required for MIPS, the interfacial structure and properties are very\nsimilar for ABP with purely repulsive (WCA-LJ model truncated at its minimum)\nand when the interaction includes a range of the LJ attractive force."
    },
    {
        "anchor": "Quantum Charge Transport and Conformational Dynamics of Macromolecules: We study the dynamics of quantum excitations inside macromolecules which can\nundergo conformational transitions. In the first part of the paper, we use the\npath integral formalism to rigorously derive a set of coupled equations of\nmotion which simultaneously describe the molecular and quantum transport\ndynamics, and obey the fluctuation/dissipation relationship. We also introduce\nan algorithm which yields the most probable molecular and quantum transport\npathways in rare, thermally-activated reactions. In the second part of the\npaper, we apply this formalism to simulate the propagation of a charge during\nthe collapse of a polymer from an initial stretched conformation to a final\nglobular state. We find that the charge dynamics is quenched when the chain\nreaches a molten globule state. Using random matrix theory we show that this\ntransition is due to an increase of quantum localization driven by dynamical\ndisorder.",
        "positive": "Phase field modeling of partially saturated deformable porous media: A poromechanical model of partially saturated deformable porous media is\nproposed based on a phase field approach at modeling the behavior of the\nmixture of liquid water and wet air, which saturates the pore space, the phase\nfield being the saturation (ratio). While the standard retention curve is\nexpected still to provide the intrinsic retention properties of the porous\nskeleton, depending on the porous texture, an enhanced description of surface\ntension between the wetting (liquid water) and the non-wetting (wet air) fluid,\noccupying the pore space, is stated considering a regularization of the phase\nfield model based on an additional contribution to the overall free energy\ndepending on the saturation gradient. The aim is to provide a more refined\ndescription of surface tension interactions.\n  An enhanced constitutive relation for the capillary pressure is established\ntogether with a suitable generalization of Darcy's law, in which the gradient\nof the capillary pressure is replaced by the gradient of the so-called\ngeneralized chemical potential, which also accounts for the \\lq\\lq\nforce\\rq\\rq\\, associated to the local free energy of the phase field model. A\nmicro-scale heuristic interpretation of the novel constitutive law of capillary\npressure is proposed, in order to compare the envisaged model with that one\nendowed with the concept of average interfacial area.\n  The considered poromechanical model is formulated within the framework of\nstrain gradient theory in order to account for possible effects, at laboratory\nscale, of the micro-scale hydro-mechanical couplings between highly-localized\nflows (fingering) and localized deformations of the skeleton (fracturing)."
    },
    {
        "anchor": "Interstitial flows regulate collective cell migration heterogeneity\n  through adhesion: The migration behaviors of cancer cells are known to be heterogeneous.\nHowever, the interplay between the adhesion interactions, dynamical shape\nchanges and fluid flows in regulating cell migration heterogeneity and\nplasticity during cancer metastasis is still elusive. To further quantitative\nunderstanding of cell motility and morphology, we develop a theory using\nstochastic quantization method that describes the role of biophysical cues in\nregulating diverse cell motility. We show that the cumulative effect of time\ndependent adhesion interactions that determine the structural rearrangements\nand self-generated force due to actin remodeling, dictate the super-diffusive\nmotion of mesenchymal phenotype in the absence of flow. Interstitial flows\nregulate cell motility phenotype and promote the amoeboid over mesenchymal\nmotility through adhesion interactions. Cells exhibit a dynamical slowing down\nof collective migration, with a decreasing degree of super-diffusion.\nMesenchymal cells are more persistent and diffusive compared to amoeboid cells.\nOur findings, suggest a mechanism of Interstitial flow induced directed motion\nof cancer cells through adhesion, and provide the much needed insight into a\nrecent experimental observation concerning the diverse motility of breast\ncancer cells.",
        "positive": "Thermal Transport Dynamics in Active Heat Transfer Fluids (AHTF): We present results of molecular dynamics (MD) calculations of the effective\nthermal conductivity of nanofluids containing self-propelled nanoparticles. The\ntranslational and rotational dynamics observed in the simulations follow the\nbehavior expected from the standard theoretical analysis of Brownian and\nself-propelled nanoparticles. The superposition of self-propulsion and\nrotational Brownian motion causes the behavior of the self-propelled\nnanoparticles to resemble Brownian diffusion with an effective coefficient that\nis larger than the standard Brownian value by a factor of several thousand. As\na result of the enhanced diffusion (and the convective mixing resulting from\nthe motion), we observe a discriminable increase of the effective thermal\nconductivity of the solution. While the increases we observe are in the range\nof several percent, they are significant considering that, without propulsion,\nthe nanofluid thermal conductivity is essentially not affected by the Brownian\nmotion and can be understood within the effective medium theory of thermal\nconduction. Our results constitute a proof of concept that self-propelled\nparticles have the potential to enhance thermal conductivity of the liquid in\nwhich they are immersed, an idea that could ultimately be implemented in a\nbroad variety of cooling applications."
    },
    {
        "anchor": "Complex Spontaneous Flows and Concentration Banding in Active Polar\n  Films: We study the dynamical properties of active polar liquid crystalline films.\nLike active nematic films, active polar films undergo a dynamical transitions\nto spontaneously flowing steady-states. Spontaneous flow in polar fluids is,\nhowever, always accompanied by strong concentration inhomogeneities or\n\"banding\" not seen in nematics. In addition, a spectacular property unique to\npolar active films is their ability to generate spontaneously oscillating and\nbanded flows even at low activity. The oscillatory flows become increasingly\ncomplicated for strong polarity.",
        "positive": "Hydrophobic interactions with coarse-grained model for water: Integral equation theory is applied to a coarse-grained model of water to\nstudy potential of mean force between hydrophobic solutes. Theory is shown to\nbe in good agreement with the available simulation data for methane-methane and\nfullerene-fullerene potential of mean force in water; the potential of mean\nforce is also decomposed into its entropic and enthalpic contributions. Mode\ncoupling theory is employed to compute self-diffusion coefficient of water, as\nwell as diffusion coefficient of a dilute hydrophobic solute; good agreement\nwith molecular dynamics simulation results is found."
    },
    {
        "anchor": "Curvature-driven instabilities in thin active shells: Spontaneous material shape changes, such as swelling, growth or thermal\nexpansion, can be used to trigger dramatic elastic instabilities in thin\nshells. These instabilities originate in geometric incompatibility between the\npreferred extrinsic and intrinsic curvature of the shell, which may be modified\nby active deformations through the thickness and in plane respectively. Here,\nwe solve the simplest possible model of such instabilities, which assumes the\nshells are shallow, thin enough to bend but not stretch, and subject to\nhomogeneous preferred curvatures. We consider separately the cases of zero,\npositive and negative Gaussian curvature. We identify two types of\nsuper-critical symmetry breaking instability, in which the shell's principal\ncurvature spontaneously breaks discrete up-down symmetry and continuous planar\nisotropy respectively. These are then augmented by inversion instabilities, in\nwhich the shell jumps sub-critically between up/down broken symmetry states,\nand rotation instabilities, in which the curvatures rotate by 90 degrees\nbetween states of broken isotropy without release of energy. Each instability\nhas a thickness independent threshold value for the preferred extrinsic\ncurvature proportional to the square-root of Gauss curvature. Finally, we show\nthat the threshold for the isotropy-breaking instability is the same for deep\nspherical caps, in good agreement with recently published data.",
        "positive": "Inverse methods for design of soft materials: Functional soft materials, comprising colloidal and molecular building blocks\nthat self-organize into complex structures as a result of their tunable\ninteractions, enable a wide array of technological applications. Inverse\nmethods provide systematic means for navigating their inherently\nhigh-dimensional design spaces to create materials with targeted properties.\nWhile multiple physically motivated inverse strategies have been successfully\nimplemented in silico, their translation to guiding experimental materials\ndiscovery has thus far been limited to a handful of proof-of-concept studies.\nIn this Perspective, we discuss recent advances in inverse methods for design\nof soft materials that address two challenges: (1) methodological limitations\nthat prevent such approaches from satisfying design constraints and (2)\ncomputational challenges that limit the size and complexity of systems that can\nbe addressed. Strategies that leverage machine learning have proven\nparticularly effective, including methods to discover order parameters that\ncharacterize complex structural motifs and schemes to efficiently compute\nmacroscopic properties from the underlying structure. We also highlight\npromising opportunities to improve the experimental realizability of materials\ndesigned computationally, including discovery of materials with functionality\nat multiple thermodynamic states, design of externally directed assembly\nprotocols that are simple to implement in experiments, and strategies to\nimprove the accuracy and computational efficiency of experimentally relevant\nmodels."
    },
    {
        "anchor": "Spatially Resolved Thermodynamic Integration: An Efficient Method to\n  Compute Chemical Potentials of Dense Fluids: Many popular methods for the calculation of chemical potentials rely on the\ninsertion of test particles into the target system. In the case of liquids and\nliquid mixtures, this procedure increases in difficulty upon increasing density\nor concentration, and the use of sophisticated enhanced sampling techniques\nbecomes inevitable. In this work we propose an alternative strategy, spatially\nresolved thermodynamic integration, or SPARTIAN for short. Here, molecules are\ndescribed with atomistic resolution in a simulation subregion, and as ideal gas\nparticles in a larger reservoir. All molecules are free to diffuse between\nsubdomains adapting their resolution on the fly. To enforce a uniform density\nprofile across the simulation box, a single-molecule external potential is\ncomputed, applied, and identified with the difference in chemical potential\nbetween the two resolutions. Since the reservoir is represented as an ideal gas\nbath, this difference exactly amounts to the excess chemical potential of the\ntarget system. The present approach surpasses the high density/concentration\nlimitation of particle insertion methods because the ideal gas molecules\nentering the target system region spontaneously adapt to the local environment.\nThe ideal gas representation contributes negligibly to the computational cost\nof the simulation, thus allowing one to make use of large reservoirs at minimal\nexpenses. The method has been validated by computing excess chemical potentials\nfor pure Lennard-Jones liquids and mixtures, SPC and SPC/E liquid water, and\naqueous solutions of sodium chloride. The reported results well reproduce\nliterature data for these systems.",
        "positive": "Homogeneous crystallization in four-dimensional Lennard-Jones liquids: We report the first observation of homogeneous crystallization in simulated\nhigh-dimensional ($d > 3$) liquids that follow physically realistic dynamics\nand have system sizes that are large enough to eliminate the possibility that\ncrystallization was induced by the periodic boundary conditions. Supercooled\nfour-dimensional (4D) Lennard-Jones liquids maintained at zero pressure and\nconstant temperatures $0.59 < T < 0.63$ crystallized within $\\sim 2 \\times\n10^4\\tau$, where $\\tau$ is the LJ time unit. WCA liquids that were maintained\nat the same densities and temperatures at which their LJ counterparts nucleated\ndid not crystallize even after $2.5\\times 10^5\\tau$, showing that the presence\nof long-ranged attractive interactions dramatically speeds up 4D\ncrystallization, much as it does in 3D. However, the overlap of the liquid and\ncrystalline phases' local-bond-order distributions is much smaller for LJ than\nfor WCA systems, which is the opposite of the 3D trend. This implies that the\nwidely accepted hypothesis that increasing geometrical frustration rapidly\nsuppresses crystallization as the spatial dimension $d$ increases is only\ngenerally valid in the absence of attractive interparticle forces."
    },
    {
        "anchor": "Rheological properties vs Local Dynamics in model disordered materials\n  at Low Temperature: We study the rheological response at low temperature of a sheared model\ndisordered material as a function of the bond rigidity. We find that the flow\ncurves follow a Herschel-Bulkley law, whatever is the bond rigidity, with an\nexponent close to 0.5. Interestingly, the apparent viscosity can be related to\na single relevant time scale $t_{rel}$, suggesting a strong connection between\nthe local dynamics and the global mechanical behaviour. We propose a model\nbased on the competition between the nucleation and the avalanche-like\npropagation of spatial strain heterogeneities. This model can explain the\nHerschel-Bulkley exponent on the basis of the size dependence of the\nheterogeneities on the shear rate.",
        "positive": "Theory of Gelation: Post-Gelation Behavior: Within the framework of the random distribution assumption of cyclic bonds,\nthe preceding theory of gelation is extended to mixing systems with various\nfunctionalities. To examine the validity of the assumption, the theory is\napplied to experimental data in polyurethane network formation, the result\nshowing the soundness of the theory for the prediction of gel points and gel\nfraction."
    },
    {
        "anchor": "Review: Dynamics of Crowded Macromolecules/Interacting Brownian\n  Particles: I review theoretical treatments of diffusion in crowded (i.~e., non-dilute)\nsolutions of globular macromolecules. The focus is on the classical\nstatistico-mechanical literature, much of which dates to before 1990. Classes\nof theoretical models include continuum treatments, correlation function\ndescriptions, generalized Langevin equation descriptions, Smoluchowski and\nMori-Zwanzig descriptions, and a brief but encouraging comparison with\nexperimental results. The primary emphasis is on measurements made with\nquasi-elastic light scattering spectroscopy; I also discuss outcomes from\nfluorescence photobleaching recovery, fluorescence correlation spectroscopy,\npulsed-gradient spin-echo nuclear magnetic resonance, and raster image\ncorrelation spectroscopy. I close with a list of theoretical papers on the\ngeneral topic.",
        "positive": "Correlation between kinetic fragility and Poisson's ratio from analysis\n  of data for soft colloids: We consider the link between fragility and elasticity that follows from\nanalysis of the data for a set of soft-colloid materials consisting of\ndeformable spheres reported by Mattsson et. al., in Nature vol 462, 83 (2009).\nFragility index for a soft-colloid is obtained from the density dependence of\nthe long time relaxation near a so-called glass transition point. In addition,\nwe fit data for the high frequency shear modulus for the respective\nsoft-colloid to a corresponding theoretical expression for the same modulus.\nThis expression for the elastic constant is in terms of the corresponding pair\ncorrelation function for the liquid treated as of uniform density. The pair\ncorrelation function is adjusted through a proper choice of the parameters for\nthe two body interaction potential for the respective soft-colloid material.\nThe nature of correlation between the fragility and Poisson ratio observed for\nthe soft colloids is qualitatively different, as compared to the same for\nmolecular glasses. The observed link between fragility of a metastable liquid\nand its elastic coefficients is a manifestation of the effects of structure of\nthe fluid on its dynamics."
    },
    {
        "anchor": "Unraveling the vascular fate of deformable circulating tumor cells via a\n  hierarchical computational model: Distant spreading of primary lesions is modulated by the vascular dynamics of\ncirculating tumor cells (CTCs) and their ability to establish metastatic\nniches. While the mechanisms regulating CTC homing in specific tissues are yet\nto be elucidated, it is well documented that CTCs possess different size,\nbiological properties and deformability. A computational model is presented to\npredict the vascular transport and adhesion of CTCs in whole blood. A\nLattice-Boltzmann method, which is employed to solve the Navier-Stokes equation\nfor the plasma flow, is coupled with an Immersed Boundary Method. The vascular\ndynamics of a CTC is assessed in large and small microcapillaries. The CTC\nshear modulus k ctc is varied returning CTCs that are stiffer, softer and\nequally deformable as compared to RBCs. In large microcapillaries, soft CTCs\nbehave similarly to RBCs and move away from the vessel walls; whereas rigid\nCTCs are pushed laterally by the fast moving RBCs and interact with the vessel\nwalls. Three adhesion behaviors are observed, firm adhesion, rolling and\ncrawling over the vessel walls, depending on the CTC stiffness. On the\ncontrary, in small microcapillaries, rigid CTCs are pushed downstream by a\ncompact train of RBCs and cannot establish any firm interaction with the vessel\nwalls; whereas soft CTCs are squeezed between the vessel wall and the RBC train\nand rapidly establish firm adhesion. These findings document the relevance of\ncell deformability in CTC vascular adhesion and provide insights on the\nmechanisms regulating metastasis formation in different vascular districts.",
        "positive": "Photonic Hall Effect in ferrofluids: Theory and Experiments: An experimental and theoretical study on the Photonic Hall Effect (PHE) in\nliquid and gelled samples of ferrofluids is presented. The ferrofluids are\naqueous colloidal suspensions of Fe(_{2})CoO(_{4}) particles, which can be\nconsidered as anisotropic and absorbing Rayleigh scatterers.\n  The PHE is found to be produced by the orientation of the magnetic moments of\nthe particles, as is also the case for the Faraday effect. The dependence of\nthe PHE with respect to the concentration of the scatterers, the magnetic field\nand the polarization of the incident light is measured in liquid and in gelled\nsamples and is compared to a simple model based on the use of a scattering\nmatrix and the single scattering approximation."
    },
    {
        "anchor": "Using an added liquid to suppress drying defects in hard particle\n  coatings: Hypothesis: Lateral accumulation and film defects during drying of hard\nparticle coatings is a common problem, typically solved using polymeric\nadditives and surface active ingredients, which require further processing of\nthe dried film. Capillary suspensions with their tunable physical properties,\ndevoid of polymers, offer new pathways in producing uniform and defect free\nparticulate coatings.\n  Experiments: We investigated the effect of small amounts of secondary liquid\non the coating's drying behavior. Stress build-up and weight loss in a\ntemperature and humidity controlled drying chamber were simultaneously\nmeasured. Changes in the coating's reflectance and height profile over time\nwere related with the weight loss and stress curve.\n  Findings: Capillary suspensions dry uniformly without defects. Lateral drying\nis inhibited by the high yield stress, causing the coating to shrink to an even\nheight. The bridges between particles prevent air invasion and extend the\nconstant drying period. The liquid in the lower layers is transported to the\ninterface via corner flow within surface pores, leading to a partially dry\nlayer near the substrate while the pores above are still saturated. Using\ncapillary suspensions for hard particle coatings results in more uniform,\ndefect free films with better printing characteristics, rendering high additive\ncontent obsolete.",
        "positive": "Hydrodynamics in bridging and aggregation of two colloidal particles in\n  a near-critical binary mixture: We investigate bridging and aggregation of two colloidal particles in a\nnear-critical binary mixture when the fluid far from the particles is outside\nthe coexistence (CX) curve and is rich in the component disfavored by the\ncolloid surfaces. In such situations, the adsorption-induced interaction is\nenhanced, leading to bridging and aggregation of the particles. We realize\nbridging firstly by changing the temperature with a fixed interparticle\nseparation and secondly by letting the two particles aggregate. The\ninterparticle attractive force dramatically increases upon bridging. The\ndynamics is governed by hydrodynamic flow around the colloid surfaces. In\naggregation, the adsorption layers move with the particles and squeezing occurs\nat narrow separation. We take into account the renormalization effect due to\nthe critical fluctuations using the recent local functional theory [J. Chem.\nPhys. 136, 114704 (2012)]."
    },
    {
        "anchor": "Huge Seebeck coefficients in non-aqueous electrolytes: The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium\nnitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in\n1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range\nfrom T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few\nhundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here\nwe report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium\nnitrate in 1-dodecanol. These striking results open the question of\nunexpectedly large kosmotrope or \"structure making\" effects of\ntetraalkylammonium ions on the structure of alcohols.",
        "positive": "Transient flows and migration in granular suspensions: key role of\n  Reynolds-like dilatancy: We investigate the transient dynamics of a sheared suspension of neutrally\nbuoyant particles under pressure-imposed conditions, subject to a sudden change\nin shear rate or external pressure. Discrete Element Method simulations show\nthat, depending on the flow parameters (particle and system size, initial\nvolume fraction), the early stress response of the suspension may strongly\ndiffer from the prediction of the Suspension Balance Model based on the\nsteady-state rheology. We show that a two-phase model incorporating the\nReynolds-like dilatancy law of Pailha & Pouliquen (2009), which prescribes the\ndilation rate of the suspension over a strain scale $\\gamma_0$, quantitatively\ncaptures the suspension dilation/compaction over the whole range of parameters\ninvestigated. Together with the Darcy flow induced by the pore pressure\ngradient during dilation or compaction, this Reynolds-like dilatancy implies\nthat the early stress response of the suspension is nonlocal, with a nonlocal\nlength scale $\\ell$ which scales with the particle size and diverges\nalgebraically at jamming. In regions affected by $\\ell$, the stress level is\nfixed, not by the steady-state rheology, but by the Darcy fluid pressure\ngradient resulting from the dilation/compaction rate. Our results extend the\nvalidity of the Reynolds-like dilatancy flow rule, initially proposed for\njammed suspensions, to flowing suspension below $\\phi_\\mathrm{c}$, thereby\nproviding a unified framework to describe dilation and shear-induced migration.\nThey pave the way for understanding more complex unsteady flows of dense\nsuspensions, such as impacts, transient avalanches or the impulsive response of\nshear-thickening suspensions."
    },
    {
        "anchor": "Dynamics, dynamic soft elasticity and rheology of smectic-C elastomers: We present a theory for the low-frequency, long-wavelength dynamics of soft\nsmectic-C elastomers with locked-in smectic layers. Our theory, which goes\nbeyond pure hydrodynamics, predicts a dynamic soft elasticity of these\nelastomers and allows us to calculate the storage and loss moduli relevant for\nrheology experiments as well as the mode structure.",
        "positive": "Water spring: a model for bouncing drops: It has been shown that a water drop can bounce persistently, when thrown on a\nsuper-hydrophobic substrate. We present here scaling arguments which allow us\nto predict the maximal deformation and the contact time of the drop. This\napproach is completed by a model describing the flow inside the drop, and by\noriginal experimental data."
    },
    {
        "anchor": "Nematic Films at Chemically Structured Surfaces: We investigate theoretically the morphology of a thin nematic film adsorbed\nat flat substrate patterned by stripes with alternating aligning properties,\nnormal and tangential respectively. We construct a simple \"exactly-solvable\"\neffective interfacial model where the liquid crystal distortions are accounted\nfor via an effective interface potential. We find that chemically patterned\nsubstrates can strongly deform the nematic-air interface. The amplitude of this\nsubstrate-induced undulations increases with decreasing average film thickness\nand with increasing surface pattern pitch. We find a regime where the\ninterfacial deformation may be described in terms of a material-independent\nuniversal scaling function. Surprisingly, the predictions of the effective\ninterfacial model agree semi-quantitatively with the results of the numerical\nsolution of a full model based on the Landau-de Gennes theory coupled to a\nsquare-gradient phase field free energy functional for a two phase system.",
        "positive": "Response of bubbles to diagnostic ultrasound: a unifying theoretical\n  approach: The scattering of ultrasound from bubbles of micrometer-sized radius, such as\nused in contrast enhancers for ultrasound diagnostics, is studied. We show that\nsound scattering and ``active'' emission of sound from oscillating bubbles are\nnot contradictory, but are just two different aspects derived from the same\nphysics. Treating the bubble as a nonlinear oscillator, we arrive at general\nformulas for scattering and absorption cross sections. We show that several\nwell-known formulas are recovered in the linear limit of this ansatz. In the\ncase of strongly nonlinear oscillations, however, the cross sections can be\nlarger than those for linear response by several orders of magnitude. The major\npart of the incident sound energy is then converted into emitted sound, unlike\nwhat happens in the linear case, where the absorption cross sections exceed the\nscattering cross sections."
    },
    {
        "anchor": "Dynamics of Highly Supercooled Liquids:Heterogeneity, Rheology, and\n  Diffusion: Highly supercooled liquids with soft-core potentials are studied via\nmolecular dynamics simulations in two and three dimensions in quiescent and\nsheared conditions.We may define bonds between neighboring particle pairs\nunambiguously owing to the sharpness of the first peak of the pair correlation\nfunctions. Upon structural rearrangements, they break collectively in the form\nof clusters whose sizes grow with lowering the temperature $T$. The bond life\ntime $\\tau_b$, which depends on $T$ and the shear rate $\\gdot$, is on the order\nof the usual structural or $\\alpha$ relaxation time $\\tau_{\\alpha}$ in weak\nshear $\\gdot \\tau_{\\alpha} \\ll 1$, while it decreases as $1/\\gdot$ in strong\nshear $\\gdot\\tau_{\\alpha} \\gg 1$ due to shear-induced cage breakage.\nAccumulated broken bonds in a time interval ($\\sim 0.05\\tau_b$) closely\nresemble the critical fluctuations of Ising spin systems. For example, their\nstructure factor is well fitted to the Ornstein-Zernike form, which yields the\ncorrelation length $\\xi$ representing the maximum size of the clusters composed\nof broken bonds. We also find a dynamical scaling relation, $\\tau_b \\sim\n\\xi^{z}$, valid for any $T$ and $\\gdot$ with $z=4$ in two dimensions and $z=2$\nin three dimensions. The viscosity is of order $\\tau_b$ for any $T$ and\n$\\gdot$, so marked shear-thinning behavior emerges. The shear stress is close\nto a limiting stress in a wide shear region. We also examine motion of tagged\nparticles in shear in three dimensions. The diffusion constant is found to be\nof order $\\tau_b^{-\\nu}$ with $\\nu=0.75 \\sim 0.8$ for any $T$ and $\\gdot$, so\nit is much enhanced in strong shear compared with its value at zero shear. This\nindicates breakdown of the Einstein-Stokes relation in accord with experiments.\nSome possible experiments are also proposed.",
        "positive": "Competition between capillarity, layering and biaxiality in a confined\n  liquid crystal: The effect of confinement on the phase behaviour and structure of fluids made\nof biaxial hard particles (cuboids) is examined theoretically by means of\nOnsager second-order virial theory in the limit where the long particle axes\nare frozen in a mutually parallel configuration. Confinement is induced by two\nparallel planar hard walls (slit-pore geometry), with particle long axes\nperpendicular to the walls (perfect homeotropic anchoring). In bulk, a\ncontinuous nematic-to-smectic transition takes place, while shape anisotropy in\nthe (rectangular) particle cross section induces biaxial ordering. As a\nconsequence, four bulk phases, uniaxial and biaxial nematic and smectic phases,\ncan be stabilised as the cross-sectional aspect ratio is varied. On confining\nthe fluid, the nematic-to-smectic transition is suppressed, and either uniaxial\nor biaxial phases, separated by a continuous trasition, can be present. Smectic\nordering develops continuously from the walls for increasing particle\nconcentration (in agreement with the supression of nematic-smectic second order\ntransition at confinement), but first-order layering transitions, involving\nstructures with n and n+1 layers, arise in the confined fluid at high\nconcentration. Competition between layering and uniaxial-biaxial ordering leads\nto three different types of layering transitions, at which the two coexisting\nstructures can be both uniaxial, one uniaxial and another biaxial, or both\nbiaxial. Also, the interplay between molecular biaxiality and wall interactions\nis very subtle: while the hard wall disfavours the formation of the biaxial\nphase, biaxiality is against the layering transitions, as we have shown by\ncomparing the confined phase behaviour of cylinders and cuboids. The predictive\npower of Onsager theory is checked and confirmed by performing some\ncalculations based on fundamental-measure theory."
    },
    {
        "anchor": "Dynamics and polarization of superparamagnetic chiral nanomotors in a\n  rotating magnetic field: Externally powered magnetic nanomotors are of particular interest due to the\npotential use for \\emph{in vivo} biomedical applications. Here we develop a\ntheory for dynamics and polarization of recently fabricated superparamagnetic\nchiral nanomotors powered by a rotating magnetic field. We study in detail\nvarious experimentally observed regimes of the nanomotor dynamic orientation\nand propulsion and establish the dependence of these properties on polarization\nand geometry of the propellers. Based on the proposed theory we introduce a\nnovel \"steerability\" parameter $\\gamma$ that can be used to rank polarizable\nnanomotors by their propulsive capability. The theoretical predictions of the\nnanomotor orientation and propulsion speed are in excellent agreement with\navailable experimental results. Lastly, we apply slender-body approximation to\nestimate polarization anisotropy and orientation of the easy-axis of\nsuperparamagnetic helical propellers.",
        "positive": "Understanding tetrahedral liquids through patchy colloids: We investigate the structural properties of a simple model for tetrahedral\npatchy colloids in which the patch width and the patch range can be tuned\nindependently. For wide bond angles, a fully bonded network can be generated by\nstandard Monte Carlo or molecular dynamics simulations of the model, providing\na neat method for generating defect-free random tetrahedral networks. This\noffers the possibility of focusing on the role of the patch angular width on\nthe structure of the fully bonded network. The analysis of the fully bonded\nconfigurations as a function of the bonding angle shows how the bonding angle\ncontrols the system compressibility, the strength of the pre-peak in the\nstructure factor and ring size distribution. Comparison with models of liquid\nwater and silica allows us to find the best mapping between these continuous\npotentials and the colloidal one. Building on previous studies focused on the\nconnection between angular range and crystallization, the mapping makes it\npossible to shed new light on the glass-forming ability of network-forming\ntetrahedral liquids."
    },
    {
        "anchor": "Vortices enhance diffusion in dense granular flows: This Letter introduces unexpected diffusion properties in dense granular\nflows, and shows that they result from the development of partially jammed\nclusters of grains, or granular vortices. Transverse diffusion coefficients $D$\nand average vortex sizes $\\ell$ are systematically measured in simulated plane\nshear flows at differing internal numbers $I$ revealing (i) a strong deviation\nfrom the expected scaling $D\\propto d^2 \\dot \\gamma$ involving the grain size\n$d$ and shear rate $\\dot \\gamma$ and (ii) an increase in average vortex size\n$\\ell$ at low $I$, following $\\ell\\propto dI^{-\\frac{1}{2}}$ but limited by the\nsystem size. A general scaling $D\\propto \\ell d \\dot \\gamma $ is introduced\nthat captures all the measurements and highlights the key role of vortex size.\nThis leads to establishing a scaling for the diffusivity in dense granular flow\nas $D\\propto d^2 \\sqrt{\\dot \\gamma/ t_i}$ involving the geometric average of\nshear time $1/\\dot\\gamma$ and inertial time $t_i$ as the relevant time scale.\nAnalysis of grain trajectories further evidence that this diffusion process\narises from a vortex-driven random walk.",
        "positive": "Disorder, pre-stress and non-affinity in polymer 8-chain models: To assess the role of single-chain elasticity, non-affine strain fields and\npre-stressed reference states we present and discuss the results of numerical\nand analytical analyses of modified 8-chain Arruda-Boyce model for cross-linked\npolymer networks. This class of models has proved highly successful in modeling\nthe finite-strain response of flexible rubbers. We extend it to include the\neffects of spatial disorder and the associated non-affinity, and use it to\nassess the validity of replacing the constituent chain's nonlinear elastic\nresponse with equivalent linear, Hookean springs. Surprisingly, we find that\neven in the regime of linear response, the full polymer model gives very\ndifferent results from its linearized counterpart, even though none of the\nchains are stretched beyond their linear regime. We demonstrate that this\neffect is due to the fact that the polymer models are under considerable\npre-stress in their ground state. We show that pre-stress strongly suppresses\nnon-affinity in these unit cell models, resulting in a marked stiffening of the\nbulk response. The effects of pre-stress we discuss may explain why fully\naffine mechanical models, in many cases, predict the bulk mechanical response\nof disordered stiff polymer networks so well."
    },
    {
        "anchor": "Correction of Doi-Edwards' Green Function for a Chain in a Harmonic\n  Potential and its Implication for the Stress-Optical Rule: We provide a corrected Green's function for a polymer chain trapped in a\ntwo-dimensional anisotropic harmonic potential with a fixed boundary condition.\nThis Green's function is a modified version of what Doi and Edwards first\nderived to describe the polymer chain confined in the tube-like domain of\nsurrounding entangled polymers [J. Chem. Soc. Farad. Trans. II 74 (1978) 1802].\nIn contradiction to the results found by Ianniruberto and Marrucci (IM) when\napplying the Doi-Edwards Green function [J. Non-Newtonian Fluid Mech. 79 (1998)\n225], we find that the stress-optical rule is violated for any tube potential\neither circular or elliptic if the corrected Green's function is used. The\nviolation is due to the presence of the virtual springs to confine the chain in\nthe tube rather than the anisotropy of the confinement potential. On the other\nhand, Doi and Edwards used their Green's function only for estimation of the\nmonomer density along the primitive path where we find just a small correction.\nSince they did not use it for rheological calculations, the stress-optic rule\nappears to be safe for the Doi-Edwards model.",
        "positive": "Impact of dipole-dipole interactions on motility-induced phase\n  separation: We present a hydrodynamic theory for systems of dipolar active Brownian\nparticles which, in the regime of weak dipolar coupling, predicts the onset of\nmotility-induced phase separation (MIPS), consistent with Brownian dynamics\n(BD) simulations. The hydrodynamic equations are derived by explicitly\ncoarse-graining the microscopic Langevin dynamics, thus allowing for a\nquantitative comparison of parameters entering the coarse-grained model and\nparticle-resolved simulations. Performing BD simulations at fixed density, we\nfind that dipolar interactions tend to hinder MIPS, as first reported in [Liao\net al., Soft Matter, 2020, 16, 2208]. Here we demonstrate that the theoretical\napproach indeed captures the suppression of MIPS. Moreover, the analysis of the\nnumerically obtained, angle-dependent correlation functions sheds light into\nthe underlying microscopic mechanisms leading to the destabilization of the\nhomogeneous phase."
    },
    {
        "anchor": "Kinetics of charge inversion: Colloidal suspensions and polyelectrolyte solutions containing multivalent\ncounterions can exhibit some very counter-intuitive behavior usually associated\nwith the low temperature physics. There are two particularly striking phenomena\nresulting from strong electrostatic correlations. One is the like-charge\nattraction and the second is the polyion overcharging. In this contribution we\nwill concentrate on the problem of overcharging. In particular we will explore\nthe kinetic limitation to colloidal charge inversion in suspensions containing\nmultivalent counterions.",
        "positive": "Theoretical characterization of a model of aragonite crystal orientation\n  in red abalone nacre: Nacre, commonly known as mother-of-pearl, is a remarkable biomineral that in\nred abalone consists of layers of 400-nm thick aragonite crystalline tablets\nconfined by organic matrix sheets, with the $(001)$ crystal axes of the\naragonite tablets oriented to within $\\pm$ 12 degrees from the normal to the\nlayer planes. Recent experiments demonstrate that this orientational order\ndevelops over a distance of tens of layers from the prismatic boundary at which\nnacre formation begins.\n  Our previous simulations of a model in which the order develops because of\ndifferential tablet growth rates (oriented tablets growing faster than\nmisoriented ones) yield patterns of tablets that agree qualitatively and\nquantitatively with the experimental measurements. This paper presents an\nanalytical treatment of this model, focusing on how the dynamical development\nand eventual degree of order depend on model parameters. Dynamical equations\nfor the probability distributions governing tablet orientations are introduced\nwhose form can be determined from symmetry considerations and for which\nsubstantial analytic progress can be made. Numerical simulations are performed\nto relate the parameters used in the analytic theory to those in the\nmicroscopic growth model. The analytic theory demonstrates that the dynamical\nmechanism is able to achieve a much higher degree of order than naive estimates\nwould indicate."
    },
    {
        "anchor": "3D spherical-cap fitting procedure for (truncated) sessile nano- and\n  micro-droplets & -bubbles: In the study of nanobubbles, nanodroplets or nanolenses immobilised on a\nsubstrate, a cross-section of a spherical-cap is widely applied to extract\ngeometrical information from atomic force microscopy (AFM) topographic images.\nIn this paper, we have developed a comprehensive 3D spherical cap fitting\nprocedure (3D-SCFP) to extract morphologic characteristics of complete or\ntruncated spherical caps from AFM images. Our procedure integrates several\nadvanced digital image analysis techniques to construct a 3D spherical cap\nmodel, from which the geometrical parameters of the nanostructures are\nextracted automatically by a simple algorithm. The procedure takes into account\nall valid data points in the construction of the 3D spherical cap model to\nachieve high fidelity in morphology analysis. We compare our 3D fitting\nprocedure with the commonly used 2D cross-sectional profile fitting method to\ndetermine the contact angle of a complete spherical cap and a truncated\nspherical cap. The results from 3D-SCFP are consistent and accurate, while 2D\nfitting is unavoidably arbitrary in selection of the cross-section and has a\nmuch lower number of data points on which the fitting can be based, which in\naddition is biased to the top of the spherical cap. We expect that the\ndeveloped 3D spherical-cap fitting procedure will find many applications in\nimaging analysis.",
        "positive": "Computational simulations of the vibrational properties of glasses: Glasses show vibrational properties that are markedly different to those of\ncrystals which are known as phonons. For example, excess low-frequency modes\n(the so-called boson peak), vibrational localization, and strong scattering of\nphonons have been the most discussed topics, and a theoretical understanding of\nthese phenomena is challenging. To address this problem, computational\nsimulations are a powerful tool, which have been employed by many previous\nworks. In this chapter, we describe simulation methods for studying the\nvibrational properties of glasses (and any solid-state materials). We first\npresent a method for studying vibrational eigenmodes. Since vibrational motions\nof particles are excited along eigenmodes, the eigenmodes are fundamental to\ndescriptions of vibrational properties. The eigenmodes in glasses are\nnon-phonon modes in general, and some of them are even localized in space. We\nnext present a method of analysing phonon transport, which is also crucial for\nunderstanding vibrational properties. Since phonons are not eigenmodes in\nglasses, they are decomposed into several different, non-phonon eigenmodes. As\na result, phonons in glasses are strongly scattered. In addition, we describe\nhow to analyse the elastic response. The elastic response of glasses is also\nanomalous with respect to that of crystals. Finally, we briefly introduce\nrecent advances that have been achieved by means of large-scale computational\nsimulations."
    },
    {
        "anchor": "Variational theory for a single polyelectrolyte chain revisited: We reconsider the electrostatic contribution to the persistence length,\n$\\ell_e$, of a single, infinitely long charged polymer in the presence of\nscreening. A Gaussian variational method is employed, taking $\\ell_e$ as the\nonly variational parameter. For weakly charged and flexible chains, crumpling\noccurs at small length scales because conformational fluctuations overcome\nelectrostatic repulsion. The electrostatic persistence length depends on the\nsquare of the screening length, $\\ell_e\\sim\\kappa^{-2}$, as first argued by\nKhokhlov and Khachaturian by applying the Odijk-Skolnick-Fixman (OSF) theory to\na string of crumpled blobs. We compare our approach to previous theoretical\nworks (including variational formulations) and show that the result\n$\\ell_e\\sim\\kappa^{-1}$ found by several authors comes from the improper use of\na cutoff at small length scales. For highly charged and stiff chains, crumpling\ndoes not occur; here we recover the OSF result and validate the perturbative\ncalculation for slightly bent rods.",
        "positive": "Molecular simulation of melting in tetracosane (C24H50) monolayers and\n  bilayers on graphite: This work reports an investigation into the solid phase behavior and melting\nbehavior of tetracosane (C24H50) monolayers and bilayers physisorbed onto the\ngraphite basal plane using molecular dynamics simulations performed in the\nconstant (N,V,T) ensemble. This study is conducted in order to perform an\nin-depth analysis of the melting process in the quasi-2D monolayer, and compare\nthe molecular behavior in the monolayer and the bilayer at temperatures near\nand at the melting transition. The bilayer is studied by looking at quantities\nfor the bottom and top layer separately in order to break apart the evolution\nof differing structural and molecular properties that are normally associated\nwith melting in the monolayer. Simulations suggest that the melting temperature\nin the bilayer is increased significantly from that of the monolayer- which\nalready occurs at temperatures higher than the bulk tetracosane melting\ntemperature. In addition, a layer-by-layer melting effect is observed where\nsignificant factors associated with the melting transition- the formation of\nmolecular gauche defects and the perpendicular rolling of the molecule chains-\noccur in the top layer of the bilayer at significantly lower temperatures than\nthey occur in the bottom layer. Variations are conducted to better understand\nthe role of different interactions in melting of the crystalline monolayer, and\nthe results of simulations are discussed in comparison to recent STM and\ndiffraction experiment and found to be in good agreement."
    },
    {
        "anchor": "Reply to A. Louis Comment: Reply to A. Louis Comment: Fluid-solid phase-separation in hard-sphere\nmixtures is unrelated to bond-percolation",
        "positive": "Incremental dynamics of prestressed viscoelastic solids and its\n  applications in shear wave elastography: Shear wave elastography (SWE) has emerged as a new imaging modality that\nbrings tissue mechanical properties as biomarkers potentially useful for early\nand precise diagnosis. While different SWE methods have been proposed, how to\nrelate the frequency SWE measurements to quasi-static stiffnesses of tissues\nsensed by cells when prestresses are involved remains challenging. Here we\nsuggest an incremental dynamics theory for prestressed viscoelastic solids and\ninvestigate its application in SWE across a broad frequency range. To model the\npower-law dispersion relation with minimal parameters, we introduce the\nKelvin-Voigt fractional derivation model (KVFD) in the constitutive modeling of\nmaterial viscoelasticity. To validate the usefulness of the theory, we\nperformed experiments on prestressed soft materials and biological tissues. The\nresults show that the theoretical solution fits the experimental dispersion\ncurve well over a broad frequency range and accurately captures the effect of\nprestress. The theory also reveals the correlation of phase velocities and\nattenuations of shear waves with principal stresses and leads to a method for\nprobing the prestress in a viscoelastic solid without prior knowledge of the\nconstitutive parameters as validated by our numerical experiments. Taken\ntogether, our results show that the theory presented here enables the\ndevelopment of spatially resolved SWE when high-frequency shear waves get\ninvolved, and provides insights into wave motions in soft materials subject to\nprestresses."
    },
    {
        "anchor": "Coupled Bend-Twist Mechanics of Biomimetic Scale Substrate: We develop the mechanics of combined bending and twisting deformation of a\none-dimensional filamentous structure with protruding stiff fish-scale-like\nplates embedded at an angle on the surface. We develop Cosserat kinematic\nformulation along with scale contact constraints. This geometrically exact\nmodel allows us to bypass the limitations of typical finite element\ncomputations inherent in these systems when deflections are large. The derived\nstructure-property relationships reveal for the first time the combined effect\nof bending and twisting on a slender fish scale inspired substrate. The model\nsubsumes previous models on pure bending and twisting but also shows previously\nunobserved phenomena that arise due to the coupled effects of these loads. This\nincludes a new interpretation of kinematic locking behavior, multiple contact\nregimes, asymmetric sensitivities of one curvature over the other, and sharp\ntransitions in the nonlinear moment-curvature and torque-twist behaviors\nreflecting the complex scale engagement patterns.",
        "positive": "Long-time self-diffusion of Brownian Gaussian-core particles: Using extensive Brownian dynamics computer simulations, the long-time\nself-diffusion coefficient is calculated for Gaussian-core particles as a\nfunction of the number density. Both spherical and rod-like particles\ninteracting via Gaussian segments ar$ For increasing concentration we find that\nthe translational self-diffusion behaves non-monotonically reflecting the\nstructural reentrance effect in the equilibrium phase diagram. Both in the\nlimits of zero and infinite concentration, it approaches its short-time value.\nThe microscopic Medina-Noyola theory qualitatively accounts for the\ntranslational long-time diffusion. The long-time orientational diffusion\ncoefficient for Gaussian rods, on the other hand, remains very close to its\nshort-time counterpart for any density. Some implications of the weak\ntranslation-rotation coupling for ultrasoft rods are discussed."
    },
    {
        "anchor": "Sedimentation profiles of systems with reentrant melting behavior: We examine sedimentation density profiles of star polymer solutions as an\nexample of colloidal systems in sedimentation equilibrium which exhibit\nreentrant melting in their bulk phase diagram. Phase transitions between a\nfluid and a fluid with an intercalated solid are observed below a critical\ngravitational strength $\\alpha^{*}$. Characteristics of the two fluid-solid\ninterfaces in the density profiles occurring in Monte Carlo simulations for\n$\\alpha < \\alpha^{*}$ are in agreement with scaling laws put forth in the\nframework of a phenomenological theory. Furthermore we detect density\noscillations at the fluid-gas interface at high altitudes for high\ngravitational fields, which are verified with density functional theory and\nshould be observable in surface scattering experiments.",
        "positive": "Tagged-particle motion in quasi-confined colloidal hard-sphere liquids: We investigate the tagged-particle motion in a strongly interacting\nquasi-confined liquid using periodic boundary conditions along the confining\ndirection. Within a mode-coupling theory of the glass transition (MCT) we\ncalculate the self-nonergodicity parameters and the self-intermediate\nscattering function and compare them with event-driven molecular dynamics\nsimulations. We observe non-monotonic behavior for the in-plane mean-square\ndisplacement and further correlation functions which refer to higher mode\nindices encoding information about the perpendicular motion. The in-plane\nvelocity-autocorrelation function reveals persistent anti-correlations with a\nnegative algebraic power-law decay $t^{-2}$ at all packing fractions."
    },
    {
        "anchor": "Spontaneous gelation of wheat gluten proteins in a food grade solvent: Structuring wheat gluten proteins into gels with tunable mechanical\nproperties would provide more versatility for the production of plant\nprotein-rich food products. Gluten, a strongly elastic protein material\ninsoluble in water, is hardly processable. We use a novel fractionation\nprocedure allowing the isolation from gluten of a water/ethanol soluble protein\nblend, enriched in glutenin polymers at an unprecedented high ratio (50%). We\ninvestigate here the viscoelasticity of suspensions of the protein blend in a\nwater/ethanol (50/50 v/v) solvent, and show that, over a wide range of\nconcentrations, they undergo a spontaneous gelation driven by hydrogen bonding.\nWe successfully rationalize our data using percolation models and relate the\nviscoelasticity of the gels to their fractal dimension measured by scattering\ntechniques. The gluten gels display self-healing properties and their elastic\nplateaus cover several decades, from 0.01 to 10000 Pa. In particular very soft\ngels as compared to standard hydrated gluten can be produced.",
        "positive": "Odd mobility of a passive tracer in a chiral active fluid: Chiral active fluids break both time-reversal and parity symmetry, leading to\nexotic transport phenomena unobservable in ordinary passive fluids. We develop\na generalized Green-Kubo relation for the anomalous lift experienced by a\npassive tracer suspended in a two-dimensional chiral active fluid subjected to\nan applied force. This anomalous lift is characterized by a transport\ncoefficient termed the odd mobility. We validate our generalized response\ntheory using molecular dynamics simulations, and we show that the asymmetric\ntracer mobility may be understood mechanically in terms of asymmetric\ndeformations of the tracer-fluid density distribution function. We show that\nthe even and odd components of the mobility decay at different rates with\ntracer size, suggesting the possibility of size-based particle separation using\na chiral active working fluid."
    },
    {
        "anchor": "Fast Increase of Nanofluidic Slip in Supercooled Water: the Key Role of\n  Dynamics: Nanofluidics is an emerging field offering innovative solutions for energy\nharvesting and desalination. The efficiency of these applications depends\nstrongly on liquid-solid slip, arising from a favorable ratio between viscosity\nand interfacial friction. Using molecular dynamics simulations, we show that\nwall slip increases strongly when water is cooled below its melting point. For\nwater on graphene, the slip length is multiplied by up to a factor of five and\nreaches $230$nm at the lowest simulated temperature, $T \\sim 225$K; experiments\nin nanopores can reach much lower temperatures and could reveal even more\ndrastic changes. The predicted fast increase in water slip can also be detected\nat supercoolings reached experimentally in bulk water, as well as in droplets\nflowing on anti-icing surfaces. We explain the anomalous slip behavior in the\nsupercooled regime by a decoupling between viscosity and bulk density\nrelaxation dynamics, and we rationalize the wall-type dependency of the\nenhancement in terms of interfacial density relaxation dynamics. By providing\nfundamental insights on the molecular mechanisms of hydrodynamic transport in\nboth interfacial and bulk water in the supercooled regime, this study is\nrelevant to the design of anti-icing surfaces and it also paves the way to\nexplore new behaviors in supercooled nanofluidic systems.",
        "positive": "A pair potential that reproduces the shape of isochrones in molecular\n  liquids: Many liquids have curves (isomorphs) in their phase diagrams along which\nstructure, dynamics, and some thermodynamic quantities are invariant in reduced\nunits. A substantial part of their phase diagrams is thus effectively one\ndimensional. The shape of these isomorphs is described by a material-dependent\nfunction of density $h(\\rho)$, which for real liquids is well approximated by a\npower law $\\rho^\\gamma$. However, in simulations, a power law is not adequate\nwhen density changes are large; typical models such as the Lennard-Jones liquid\nshow that $\\gamma(\\rho) \\equiv \\mathrm{d} \\ln h(\\rho)/\\mathrm{d} \\ln \\rho$ is a\ndecreasing function of density. This paper presents results from computer\nsimulations using a new pair potential that diverges at a nonzero distance and\ncan be tuned to give a more realistic shape of $\\gamma(\\rho)$. Our results\nindicate that the finite size of molecules is an important factor to take into\naccount when modeling liquids over a large density range."
    },
    {
        "anchor": "A refined model for the buckling of film/substrate bilayers: The classical reduced model for a film/substrate bilayer is one in which the\nfilm is governed by the Euler-Bernoulli beam equation and the substrate is\nreplaced by an array of springs (the so-called Winkler foundation assumption).\nWe derive a refined model in which the normal and shear tractions at the bottom\nof the film are expressed in terms of the corresponding horizontal and vertical\ndisplacements, and the response of the half-space is described by the exact\ntheory. The self-consistency of the refined model is confirmed by showing that\nit yields a four-term (in the incompressible case) or six-term (in the\ncompressible case) expansion for the critical strain that agrees with the\nexpansion given by the exact theory.",
        "positive": "Scale invariance and universality of force networks in static granular\n  matter: Force networks form the skeleton of static granular matter. They are the key\ningredient to mechanical properties, such as stability, elasticity and sound\ntransmission, which are of utmost importance for civil engineering and\nindustrial processing. Previous studies have focused on the global structure of\nexternal forces (the boundary condition), and on the probability distribution\nof individual contact forces. The disordered spatial structure of the force\nnetwork, however, has remained elusive so far. Here we report evidence for\nscale invariance of clusters of particles that interact via relatively strong\nforces. We analyzed granular packings generated by molecular dynamics\nsimulations mimicking real granular matter; despite the visual variation, force\nnetworks for various values of the confining pressure and other parameters have\nidentical scaling exponents and scaling function, and thus determine a\nuniversality class. Remarkably, the flat ensemble of force configurations--a\nsimple generalization of equilibrium statistical mechanics--belongs to the same\nuniversality class, while some widely studied simplified models do not."
    },
    {
        "anchor": "Spontaneous polarization and locomotion of an active particle with\n  surface-mobile enzymes: We examine a mechanism of locomotion of active particles whose surface is\nuniformly coated with mobile enzymes. The enzymes catalyze a reaction that\ndrives phoretic flows but their homogeneous distribution forbids locomotion by\nsymmetry. We find that the ability of the enzymes to migrate over the surface\ncombined with self-phoresis can lead to a spontaneous symmetry breaking\ninstability whereby the homogeneous distribution of enzymes polarizes and the\nparticle propels. The instability is driven by the advection of enzymes by the\nphoretic flows and occurs above a critical P\\'eclet number. The transition to\npolarized motile states occurs via a supercritical or subcritical pitchfork\nbifurcations, the latter of which enables hysteresis and coexistence of uniform\nand polarized states.",
        "positive": "Vortex formation in neutron-irradiated rotating superfluid 3He-B: A convenient method to create vortices in meta-stable vortex-free superflow\nof 3He-B is to irradiate with thermal neutrons. The vortices are then formed in\na rapid non-equilibrium process with very distinctive characteristics. Two\nmodels were suggested to explain the phenomenon. One is based on the\nKibble-Zurek mechanism of defect formation in a quench-cooled second order\nphase transition. The second model builds on the instability of the moving\nfront between superfluid and normal 3He, which is created by the heating from\nthe neutron absorption event. The most detailed measurements with single-vortex\nresolution have been performed at temperatures close to Tc. We present an\noverview of the main experimental features and demonstrate that the\nmeasurements are consistent with the Kibble-Zurek picture. New data, collected\nat low temperatures, support this conclusion, but display superfluid turbulence\nas a new phenomenon. Below 0.6 Tc the damping of vortex motion from the normal\ncomponent is reduced sufficiently so that turbulent vortex dynamics become\npossible. Here a single absorbed neutron may transfer the sample from the\nmeta-stable vortex-free to the equilibrium vortex state. We find that the\nprobability for a neutron to initiate such a turbulent transition grows with\nincreasing superflow velocity and decreasing temperature."
    },
    {
        "anchor": "Delayed instabilities in viscoelastic solids through a metric\n  description: While determining the stability of an unconstrained elastic structure is a\nstraightforward task, this is not the case for viscoelastic structures.\nSeemingly elastically stable conformations of viscoelastic structures may\ngradually creep until stability is lost, and conversely, creeping does not\nnecessarily imply that a structure will eventually become unstable.\nUnderstanding instabilities in viscoelastic structures requires a more\nintuitive description of viscoelasticity to allow analytical results and\nquantitative predictions. In this work we put forward a metric description of\nviscoelasticity in which the continua is characterized by temporally evolving\nreference lengths with respect to which elastic strains are measured.\nFormulating the three dimensional theory using metric tensors we are able to\npredict which structures will exhibit delayed instability due to viscoelastic\nflow. We also quantitatively describe the viscoelastic relaxation in free\nstanding structures including cases where the relaxation leads to no apparent\nmotion. We demonstrate these results and the power of the metric approach by\nelucidating the subtle mechanism of delayed instability in elastomer shells\nshowing quantitative agreement with experimental measurements.",
        "positive": "Why Granular Media Are Thermal, and Quite Normal, After All: Two approaches exist to account for granular dynamics: The athermal one takes\ngrains as elementary, the thermal one considers the total entropy that includes\nmicroscopic degrees of freedom such as phonons and electrons. Discrete element\nmethod (DEM), granular kinetic theory and athermal statistical mechanics (ASM)\nbelong to the first, granular solid hydrodynamics (GSH) to the second one. A\ndiscussion of the conceptual differences between both is given here, leading,\namong others, to the following insights: (1) While DEM and granular kinetic\ntheory are well justified to take grains as athermal, any entropic\nconsideration is far less likely to succeed. (2) In addition to modeling grains\nas a gas of dissipative, rigid mass points, it is very helpful take grains as a\nthermal solid that has been sliced and diced. (3) General principles that\nappear invalid in granular media are repaired and restored once the true\nentropy is included. These abnormalities [such as invalidity of the\nfluctuation-dissipation theorem, granular temperatures failing to equilibrate,\nand grains at rest unable to explore the phase space] are consequences of the\nathermal approximation, not properties of granular media."
    },
    {
        "anchor": "Equilibrium orientation and adsorption of an ellipsoidal Janus particle\n  at a fluid-fluid interface: We investigate the equilibrium orientation and adsorption process of a\nsingle, ellipsoidal Janus particle at a fluid-fluid interface. The particle\nsurface comprises equally sized parts that are hydrophobic or hydrophilic. We\npresent free energy models to predict the equilibrium orientation and compare\nthe theoretical predictions with lattice Boltzmann simulations. We find that\nthe deformation of the fluid interface strongly influences the equilibrium\norientation of the Janus ellipsoid. The adsorption process of the Janus\nellipsoid can lead to different final orientations determined by the interplay\nof particle aspect ratio and particle wettablity contrast.",
        "positive": "Reversible Transition between Superoleophobic and Superoleophilic States\n  on Titania Coated Substrates by UV Irradiation: We demonstrate that tunable superoleophobic surfaces fabricated by a simple\nspin and spray coating methods of titania on silicon (Si) wafers and stainless\nsteel (SS) mesh, which possess a hierarchical re-entrant structure consisting\nof nano meter sized particles on top of micron sized particle, are able to\ninduce superoleophobicity on an oleophilic self assembled monolayer of\n1H,1H,2H,2H-perflurodecyltrichlorosilane (FDTS). Though comparison between\ndifferent coating methods, we show that spray coating on Si substrate and SS\nmesh can repel lower surface tension liquids than spin coating on Si substrates\ndue to formation of half spherical micro-particles on the spray coated\nsubstrates which is confirmed by FESEM images. Subsequently, superoleophobic\nsurfaces changes its super repellent property to complete wetting of any\nliquids under UV illumination by decomposing the FDTS molecules via photo\ncatalytic property of titania particles. The superoleophobic property was\nregained by annealing followed by grafting of FDTS on the UV treated surface\nand the total process is repeatable over number of cycles."
    },
    {
        "anchor": "Phase ordering and shape deformation of two-phase membranes: Within a coupled-field Ginzburg-Landau model we study analytically phase\nseparation and accompanying shape deformation on a two-phase elastic membrane\nin simple geometries such as cylinders, spheres and tori. Using an exact\nperiodic domain wall solution we solve for the shape and phase ordering field,\nand estimate the degree of deformation of the membrane. The results are\npertinent to a preferential phase separation in regions of differing curvature\non a variety of vesicles.",
        "positive": "Theory of a Possible Mechanism for Lubrication and Surface Protection by\n  an Electrically Neutral Hydrogels: It is demonstrated that polymers sticking out of the surface of a neutral\nhydrogel are capable of preventing adhesive forces from pulling a hydrogel into\nclose contact with a surface against which it is pressed. The proposed\nmechanism for lubrication or surface protection suggests a possible mechanism\nfor protecting the cornea from a contact lens, which is held against the eye by\nLaplace pressure. This mechanism, however, is only able to keep a gel coated\nsurface from sticking to a surface against which it is pressed, if the gel and\nsurface are bathed in fluid. Expected optical properties of the gel-surface\ninterface are discussed, in order to suggest possible ways to study the\ngel-solid interface experimentally."
    },
    {
        "anchor": "Proteins Wriggle: We propose an algorithmic strategy for improving the efficiency of Monte\nCarlo searches for the low-energy states of proteins. Our strategy is motivated\nby a model of how proteins alter their shapes. In our model when proteins fold\nunder physiological conditions, their backbone dihedral angles change\nsynchronously in groups of four or more so as to avoid steric clashes and\nrespect the kinematic conservation laws. They wriggle; they do not thrash. We\ndescribe a simple algorithm that can be used to incorporate wriggling in Monte\nCarlo simulations of protein folding. We have tested this wriggling algorithm\nagainst a code in which the dihedral angles are varied independently\n(thrashing). Our standard of success is the average root-mean-square distance\n(rmsd) between the alpha-carbons of the folding protein and those of its native\nstructure. After 100,000 Monte Carlo sweeps, the relative decrease in the mean\nrmsd, as one switches from thrashing to wriggling, rises from 11% for the\nprotein 3LZM with 164 amino acids (aa) to 40% for the protein 1A1S with 313 aa\nand 47% for the protein 16PK with 415 aa. These results suggest that wriggling\nis useful and that its utility increases with the size of the protein. One may\nimplement wriggling on a parallel computer or a computer farm.",
        "positive": "On the advanced integral equation theory description of dense Yukawa\n  one-component plasma liquids: Different advanced bridge function closures are utilized to investigate the\nstructural and thermodynamic properties of dense Yukawa one-component plasma\nliquids within the framework of integral equation theory. The isomorph-based\nempirically modified hypernetted-chain, the variational modified\nhypernetted-chain, the Rogers-Young and the Ballone-Pastore-Galli-Gazzillo\napproaches are compared at the level of thermodynamic properties, radial\ndistribution functions and bridge functions. The comparison, based on accuracy\nand computational speed, concludes that the two modified hypernetted-chain\napproaches are superior and singles out the isomorph-based variant as the most\npromising alternative to computer simulations of structural properties of dense\nYukawa liquids. The possibility of further improvement through artificial\ncross-over to exact asymptotic limits is studied."
    },
    {
        "anchor": "Effect of density on the physical aging of pressure-densified\n  polymethylmethacrylate: The rate of physical aging of glassy polymethylmethacrylate (PMMA), followed\nfrom the change in the secondary relaxation with aging, is found to be\nindependent of the density, the latter controlled by the pressure during glass\nformation. Thus, the aging behavior of the secondary relaxation is the same\nwhether the glass is more compacted or less dense than the corresponding\nequilibrium liquid. This equivalence in aging of glasses formed under different\npressures indicates that local packing is the dominant variable governing the\nglassy dynamics. One consequence is that pressure densification yields a\nreduction in the glass transition temperature. The fact that pressure\ndensification yields different glass structures is at odds with a model for\nnon-associated materials having dynamic properties exhibited by PMMA, such as\ndensity scaling of the relaxation time and isochronal superposition of the\nrelaxation dispersion.",
        "positive": "Self-Aligning Polar Active Matter: Self-alignment describes the property of a polar active unit to align or\nanti-align its orientation towards its velocity. In contrast to mutual\nalignment, where the headings of multiple active units tend to directly align\nto each other -- as in the celebrated Vicsek model --, self-alignment impacts\nthe dynamics at the individual level by coupling the rotation and displacements\nof each active unit. This enriches the dynamics even without interactions or\nexternal forces, and allows, for example, a single self-propelled particle to\norbit in a harmonic potential. At the collective level, self-alignment modifies\nthe nature of the transition to collective motion already in the mean field\ndescription, and it can also lead to other forms of self-organization such as\ncollective actuation in dense or solid elastic assemblies of active units. This\nhas significant implications for the study of dense biological systems,\nmetamaterials, and swarm robotics. Here, we review a number of models that were\nintroduced independently to describe the previously overlooked property of\nself-alignment and identify some of its experimental realizations. Our aim is\nthree-fold: (i)~underline the importance of self-alignment in active systems,\nespecially in the context of dense populations of active units and active\nsolids; (ii)~provide a unified mathematical and conceptual framework for the\ndescription of self-aligning systems; (iii)~discuss the common features and\nspecific differences of the existing models of self-alignment. We conclude by\ndiscussing promising research avenues in which the concept of self-alignment\ncould play a significant role."
    },
    {
        "anchor": "Explicit Demonstration of Geometric Frustration in Chiral Liquid\n  Crystals: Many solid materials and liquid crystals exhibit geometric frustration,\nmeaning that they have an ideal local structure that cannot fill up space. For\nthat reason, the global phase must be a compromise between the ideal local\nstructure and geometric constraints. As an explicit example of geometric\nfrustration, we consider a chiral liquid crystal confined in a long cylinder\nwith free boundaries. When the radius of the tube is sufficiently small, the\ndirector field forms a double-twist configuration, which is the ideal local\nstructure. However, when the radius becomes larger (compared with the natural\ntwist of the liquid crystal), the double-twist structure cannot fill space, and\nhence the director field must transform into some other chiral structure that\ncan fill space. This space-filling structure may be either (1) a cholesteric\nphase with single twist, or (2) a set of double-twist regions separated by a\ndisclination, which can be regarded as the beginning of a blue phase. We\ninvestigate these structures using theory and simulations, and show how the\nrelative free energies depend on the system size, the natural twist, and the\ndisclination energy. As another example, we also study a cholesteric liquid\ncrystal confined between two infinite parallel plates with free boundaries.",
        "positive": "Liquid crystalline behaviour of self-assembled Laponite PLL-PEG\n  nanocomposites: Synthetic Laponite-clay particles with platelet-like shape display strong\naging when dispersed in aqueous solutions, preventing latter from reaching\ntheir natural liquid-crystalline equilibrium state. Here we introduce a facile\nmethod that successfully prevents this aging behaviour and enables accessing\nthe systems' liquid-crystal and crystalline phases. We graft the comb-like\npolymer, poly(L-lysine)-g-poly(ethylene glycol) (PLL-PEG), onto the clay\nsurfaces from solution, thereby screening the negative surface charges and thus\nensuring steric stabilisation. We show zeta-sizer and rheology measurements,\nrespectively, confirming complete steric coating and that aging of dilute\nsamples is completely suppressed even after a year. Using evaporation as means\nto concentrate the particles, we observe various liquid crystalline textures\nunder a polarized optical microscope (POM). Upon sequential spreading and\ndrying, we are also able to obtain transparent films with hierarchical\narchitecture."
    },
    {
        "anchor": "Molecular theory for the phase equilibria and cluster distribution of\n  associating fluids with small bond angles: We develop a new theory for associating fluids with multiple association\nsites. The theory accounts for small bond angle effects such as steric\nhindrance, ring formation and double bonding. The theory is validated against\nmonte carlo simulations for the case of a fluid of patchy colloid particles\nwith three patches and is found to be very accurate. Once validated, the theory\nis applied to study the phase diagram of a fluid composed of three patch\ncolloids. It is found that bond angle has a significant effect on the phase\ndiagram and the very existence of a liquid - vapor transition.",
        "positive": "Floor- or ceiling-sliding for chemically active, gyrotactic, sedimenting\n  Janus particles: Surface bound catalytic chemical reactions self-propel chemically active\nJanus particles. In the vicinity of boundaries, these particles exhibit rich\nbehavior, such as the occurrence of wall-bound steady states of \"sliding\". Most\nactive particles tend to sediment as they are density mismatched with the\nsolution. Moreover Janus spheres, which consist of an inert core material\ndecorated with a cap-like, thin layer of a catalyst, are gyrotactic\n(\"bottom-heavy\"). Occurrence of sliding states near the horizontal walls\ndepends on the interplay between the active motion and the gravity-driven\nsedimentation and alignment. It is thus important to understand and quantify\nthe influence of these gravity-induced effects on the behavior of model\nchemically active particles moving near walls. For model gyrotactic,\nself-phoretic Janus particles, here we study theoretically the occurrence of\nsliding states at horizontal planar walls that are either below (\"floor\") or\nabove (\"ceiling\") the particle. We construct \"state diagrams\" characterizing\nthe occurrence of such states as a function of the sedimentation velocity and\nof the gyrotactic response of the particle, as well as of the phoretic mobility\nof the particle. We show that in certain cases sliding states may emerge\nsimultaneously at both the ceiling and the floor, while the larger part of the\nexperimentally relevant parameter space corresponds to particles that would\nexhibit sliding states only either at the floor or at the ceiling or there are\nno sliding states at all. These predictions are critically compared with the\nresults of previous experimental studies and our experiments conducted on\nPt-coated polystyrene and silica-core particles suspended in aqueous hydrogen\nperoxide solutions."
    },
    {
        "anchor": "Use of NMR to Test Molecular Mobility during Chemical Reaction: We evaluate critically the use of pulsed gradient spin-echo nuclear magnetic\nresonance (PGSE NMR) to measure molecular mobility during chemical reactions.\nWith raw NMR spectra available in a public depository, we confirm boosted\nmobility during the click chemical reaction (Science 2020, 369, 537) regardless\nof the order of magnetic field gradient (linearly-increasing,\nlinearly-decreasing, random sequence). We also confirm boosted mobility for the\nDiels-Alder chemical reaction. The conceptual advantage of the former chemical\nsystem is that constant reaction rate implies constant catalyst concentration,\nwhereas that of the latter is the absence of a paramagnetic catalyst,\nprecluding paramagnetism as objection to the measurements. Data and discussion\nin this paper show the reliability of experiments when one avoids convection,\nallows decay of nuclear spin magnetization between successive pulses and\nrecovery of its intensity between gradients, and satisfies quasi-steady state\nduring the time window to acquire each datum. Especially important is to make\ncomparisons on the time scale of actual chemical reaction kinetics. We discuss\npossible sources of mistaken conclusions that are desirable to avoid.",
        "positive": "Self-supporting Structure of Bird Nests: The mystery behind the bird nest's construction is not well understood. Our\nstudy focuses on the stability of a self-supporting nest-like structure.\nFirstly, we derived a stable/unstable phase boundary for the structure at the\nfixed coefficient of friction with varying geometrical parameters through force\nanalysis. Structures with a lower height and greater friction coefficient\nbetween rods are more stable. The theoretical phase boundary matched the\nexperiment results well. Then we investigate the nest structure's stability\nunder applied weight. Static structures with lower height and more rods\n(five>four>three) are more stable. Our theory also predicts a transition from\nplastic phase to elastic phase. These theoretical predictions are all confirmed\nby experiment. In the experiment, we also find that wet rod structures are more\nstable than dry ones. The structures can support up to 100 times of it's\nweight. Finally, we test the nest structure's stability under vibration. When\nthere are no weights applied, we are able to identify the appropriate geometric\nconfiguration that can withstand the greatest vibration ($1g$ of vibration\nacceleration and vibration energy up to $4\\times10^{-4}$ times of a rod's\nmaximum potential energy). The critical vibration energy and acceleration\ndepend on the applied weights. They are increased by two and one order of\nmagnitude respectively under proper weight. We also make potential energy\nanalysis to explain the stability of the structure."
    },
    {
        "anchor": "Dissipative particle dynamics study of solvent mediated transitions in\n  pores decorated with tethered polymer brushes in the form of stripes: We study self-assembly of a binary mixture of components A and B confined in\na slit-like pore with the walls modified by the stripes of tethered brushes\nmade of beads of a sort A. The emphasis is on solvent mediated transitions\nbetween morphologies when the composition of the mixture varies. For certain\nlimiting cases of the pore geometry we found that an effective reduction of the\ndimensionality may lead to a quasi one- and two-dimensional demixing. The\nchange of the environment for the chains upon changing the composition of the\nmixture from polymer melt to a good solvent conditions provides explanation for\nthe mechanism of development of several solvent mediated morphologies and, in\nsome cases, for switching between them. We found solvent mediated lamellar,\nmeander and in-lined cylinder phases. Quantitative analysis of morphology\nstructure is performed considering brush overlap integrals and gyration tensor\ncomponents.",
        "positive": "Can exact scaling exponents be obtained using the renormalization group?\n  Affirmative evidence from incompressible polar active fluids: In active matter systems, non-Gaussian, exact scaling exponents have been\nclaimed in a range of systems using perturbative renormalization group (RG)\nmethods. This is unusual compared to equilibrium systems where non-Gaussian\nexponents can typically only be approximated, even using the exact (or\nfunctional/nonperturbative) renormalization group (ERG). Here, we perform an\nERG analysis on the ordered phase of incompressible polar active fluids and\nfind that the exact non-Gaussian exponents obtained previously using a\nperturbative RG method remain valid even in this nonperturbative setting.\nFurthermore, our ERG analysis elucidates the RG flow of this system and enables\nus to identify an active Goldstone regime with nontrivial, long-ranged scaling\nbehavior for parallel and longitudinal fluctuations."
    },
    {
        "anchor": "Low, high and very-high density forms of liquid water revealed by a\n  medium-range order descriptor: We present in this paper a computational approach based on molecular dynamics\nsimulations and graph theory to characterize the structure of liquid water\nconsidering not only the local structural arrangement within the first (or\nsecond) hydration shell, but also the medium- to long-range order. In\nparticular, a new order parameter borrowed from the graph-theory framework,\ni.e. the node total communicability (NTC ), is introduced to analyze the\ndynamic network of water molecules in the liquid phase. This order parameter is\nable not only to accurately report on the different high-density-liquid (HDL)\nand low-density-liquid (LDL) water phases postulated in the liquid-liquid phase\ntransition hypothesis, but also to unveil the presence of very high density\nliquid (VHDL) clusters, both under pressure and at ambient conditions. To the\nbest of our knowledge, VHDL water patches under moderate pressures were not\nobserved before.",
        "positive": "Escape of a chain molecule over a barrier - the kink mechanism: We consider the generalization of the Kramers escape over a barrier problem\nto the case of a long chain molecule. The problem involves the motion of a\nchain molecule of $N$ segments across a region where the free energy per\nsegment is higher, so that it has to cross a barrier. We consider the limit\nwhere the length of the molecule is much larger than the width of the barrier.\nThe width is taken to be sufficiently wide that a coninuum description is\napplicable to even to the portion over the barrier. We use the Rouse model and\nanalyze the mechanism of crossing a barrier. There can be two dominant\nmechanisms. They are: end crossing and hairpin crossing. We find the free\nenergy of activation for the hairpin crossing is two times that for end\ncrossing. In both cases, the activation energy has a square root dependence on\nthe temperature $T$, leading to a non-Arrhenius form for the rate. We also show\nthat there is a special time dependent solution of the model, which corresponds\nto a kink in the chain, confined to the region of the barrier. The movement of\nthe polymer from one side to the other is equivalent to the motion of the kink\non the chain in the reverse direction. We also consider the translocation of\nhydrophilic polypeptides across hydrophobic pores, a process that is quite\ncommon in biological systems. Biological systems accomplish this by having a\nhydrophobic signal sequence at the end that goes in first. We find that for\nsuch a molecule, the transition state resembles a hook, and this is in\nagreement with presently accepted view in cell biology."
    },
    {
        "anchor": "Molecular theory of solvation: Methodology summary and illustrations: Integral equation theory of molecular liquids based on statistical mechanics\nis quite promising as an essential part of multiscale methodology for chemical\nand biomolecular nanosystems in solution. Beginning with a molecular\ninteraction potential force field, it uses diagrammatic analysis of the\nsolvation free energy to derive integral equations for correlation functions\nbetween molecules in solution in the statistical-mechanical ensemble. The\ninfinite chain of coupled integral equations for many-body correlation\nfunctions is reduced to a tractable form for 2- or 3-body correlations by\napplying the so-called closure relations. Solving these equations produces the\nsolvation structure with accuracy comparable to molecular simulations that have\nconverged but has a critical advantage of readily treating the effects and\nprocesses spanning over a large space and slow time scales, by far not feasible\nfor explicit solvent molecular simulations. One of the versions of this\nformalism, the three-dimensional reference interaction site model (3D-RISM)\nintegral equation complemented with the Kovalenko-Hirata (KH) closure\napproximation, yields the solvation structure in terms of 3D maps of\ncorrelation functions, including density distributions, of solvent interaction\nsites around a solute (supra)molecule with full consistent account for the\neffects of chemical functionalities of all species in the solution. The\nsolvation free energy and the subsequent thermodynamics are then obtained at\nonce as a simple integral of the 3D correlation functions by performing\nthermodynamic integration analytically.",
        "positive": "Comparison of the Helmholtz, Gibbs, and Collective-modes methods to\n  obtain nonaffine elastic constants: We review and compare the Born-Huang and the Lemaitre-Maloney's theories that\nlead to analytical expressions for elastic constants, accounting for affine and\nnonaffine deformations in a lattice. The Born-Huang method is based on\nHelmholtz energy while the Lemaitre-Maloney's formalism focus on Gibbs force.\nAlthough starting from different perspectives, in the linear elastic limit, and\nin equilibrium, elastic material constants must be the same in all these\nmethods. This is explicitly verified on examples of linear chains, and\nnumerical simulation of a non-centrosymmetric crystal."
    },
    {
        "anchor": "Critical Casimir interactions between Janus particles: Recently there is strong experimental and theoretical interest in studying\nthe self-assembly and the phase behavior of patchy and of Janus particles,\nwhich form colloidal suspensions. Although in this quest a variety of effective\ninteractions have been proposed and used in order to achieve directed assembly,\nthe critical Casimir effect stands out as being particularly suitable in this\nrespect because it provides both attractive and repulsive interactions as well\nas the potential of a sensitive temperature control of their strength.\nSpecifically, we have calculated the critical Casimir force between a single\nJanus particle and a laterally homogeneous substrate as well as a substrate\nwith a chemical step. We have used the Derjaguin approximation and compared it\nwith results from full mean field theory. A modification of the Derjaguin\napproximation turns out to be generally reliable. Based on this approach we\nhave derived the effective force and the effective potential between two Janus\ncylinders as well as between two Janus spheres.",
        "positive": "Twisting and buckling: a new undulation mechanism for artificial\n  swimmers: We present an artificial swimmer consisting in a long cylinder of ferrogel\nwhich is polarized transversely and in opposite directions at each extremity.\nWhen it is placed on a water film and submitted to a transverse oscillating\nmagnetic field, this artificial worm undulates and swims. Whereas symmetry\nbreaking is due to the field gradient, the undulations of the worm result from\na torsional buckling instability as the polarized ends tend to align with the\napplied magnetic field. The critical magnetic field above which buckling and\nsubsequent swimming is observed may be predicted using elasticity equations\nincluding the effect of a magnetic torque. As the length of the worm is varied,\nseveral undulation modes are observed which are in good agreement with the\nbending modes of an elastic rod with free ends."
    },
    {
        "anchor": "Effect of electric field on the photoluminescence of polymer-inorganic\n  nanoparticles composites: We report on the effect of electric field on the photoluminescence, PL, from\na composite consisting of a conjugated polymer mixed with zinc oxide\nnanoparticles. We have found that in the absence of electric field PL emission\nfrom the composite film has two maxima in the blue and green-yellow regions.\nApplication of a voltage bias to planar gold electrodes suppresses the\ngreen-yellow emission and shifts the only PL emission maximum towards the blue\nregion. Current-voltage characteristics of the polymer-nanoparticles composite\nexhibit the non-linear behavior typical of non-homogeneous polymer-inorganic\nstructures. Generation of excited states in the composite structure implies the\npresence of several radiative recombination mechanisms including formation of\npolymer-nanoparticle complexes including exciplex states and charge transfer\nbetween the polymer and nanoparticle that can be controlled by an electric\nfield.",
        "positive": "Immersed Boundary Simulations of Active Fluid Droplets: We present numerical simulations of active fluid droplets immersed in an\nexternal fluid in 2-dimensions { using} an Immersed Boundary method to simulate\nthe fluid droplet interface as a Lagrangian mesh. We present results from two\nexample systems, firstly an active isotropic fluid boundary consisting of\nparticles that can bind and unbind from the interface and generate surface\ntension gradients through active contractility. Secondly, a droplet filled with\nan active polar fluid with { homeotropic} anchoring at the droplet interface.\nThese two systems demonstrate spontaneous symmetry breaking and steady state\ndynamics resembling cell motility and division and show complex feedback\nmechanisms with minimal degrees of freedom. The simulations outlined here will\nbe useful for quantifying the wide range of dynamics observable in these active\nsystems and modelling the effects of confinement in a consistent and adaptable\nway."
    },
    {
        "anchor": "Mean-field theory for the structure of strongly interacting active\n  liquids: Active systems, which are driven out of equilibrium by local non-conservative\nforces, exhibit unique behaviors and structures with potential utility for the\ndesign of novel materials. An important and difficult challenge along the path\ntowards this goal is to precisely predict how the structure of active systems\nis modified as their driving forces push them out of equilibrium. Here, we use\ntools from liquid-state theories to approach this challenge for a classic\nminimal active matter model. First, we construct a nonequilibrium mean-field\nframework which can predict the structure of systems of weakly interacting\nparticles. Second, motivated by equilibrium solvation theories, we modify this\ntheory to extend it with surprisingly high accuracy to systems of strongly\ninteracting particles, distinguishing it from most existing similarly tractable\napproaches. Our results provide insight into spatial organization in strongly\ninteracting out-of-equilibrium systems.",
        "positive": "High-speed confined granular flows down inclines revisited: Recent numerical work has shown that high-speed confined granular flows down\ninclines exhibit a rich variety of flow patterns, including dense\nunidirectional flows, flows with longitudinal vortices and supported flows\ncharacterized by a dense core surrounded by a dilute hot granular gas (Brodu et\nal, JFM 2015). Here, we revisit the results obtained by Brodu et al. (JFM,\n2015) and present new features characterizing these flows. In particular, we\nprovide vertical and transverse profiles for the packing fraction, velocity and\ngranular temperature.We also characterize carefully the transition between the\ndifferent flow regimes and show that the packing fraction and the vorticity can\nbe successfully used to describe these transitions. Additionally, we emphasize\nthat the effective friction at the basal and side walls can be described by a\nunique function of a dimensionless number which is the analog of a Froude\nnumber: $Fr=V/\\sqrt{gH\\cos \\theta}$ where $V$ is the particle velocity at the\nwalls, $\\theta$ is the inclination angle and $H$ the particle holdup (defined\nas the depth-integrated particle volume fraction). This universal function\nbears some similarities with the $\\mu(I)$ rheological curve derived for dense\ngranular flows."
    },
    {
        "anchor": "Parallel stability analysis of membrane lamellar structures and foam\n  films: In the frames of the DLVO theory the root mean square amplitude of capillary\nwaves in a thin liquid film is calculated and its dependence on some important\nphysical parameters is unveiled. Two important models are considered: films\nwith classical interfaces and films between lipid bilayers. The performed\nnumerical analysis demonstrates essential difference in their behavior due to\nthe different elastic properties of the film surfaces. It is shown that the\nfilm lifetime is significantly long at some magic film radii.",
        "positive": "Frictional dissipation of polymeric solids vs interfacial glass\n  transition: We present single contact friction experiments between a glassy polymer and\nsmooth silica substrates grafted with alkylsilane layers of different coverage\ndensities and morphologies. This allows us to adjust the polymer/substrate\ninteraction strength. We find that, when going from weak to strong interaction,\nthe response of the interfacial junction where shear localizes evolves from\nthat of a highly viscous threshold fluid to that of a plastically deformed\nglassy solid. This we analyse as resulting from an interaction-induced\n``interfacial glass transition'' helped by pressure."
    },
    {
        "anchor": "Stochastic Approach to Plasticity and Yield in Amorphous Solids: We focus on the probability distribution function (pdf) $P(\\Delta \\gamma;\n\\gamma)$ where $\\Delta \\gamma$ are the {\\em measured} strain intervals between\nplastic events in an athermal strained amorphous solids, and $\\gamma$ measures\nthe accumulated strain. The tail of this distribution as $\\Delta \\gamma\\to 0$\n(in the thermodynamic limit) scales like $\\Delta \\gamma^\\eta$. The exponent\n$\\eta$ is related via scaling relations to the tail of the pdf of the\neigenvalues of the {\\em plastic modes} of the Hessian matrix $P(\\lambda)$ which\nscales like $\\lambda^\\theta$, $\\eta=(\\theta-1)/2$. The numerical values of\n$\\eta$ or $\\theta$ can be determined easily in the unstrained material and in\nthe yielded state of plastic flow. Special care is called for in the\ndetermination of these exponents between these states as $\\gamma$ increases.\nDetermining the $\\gamma$ dependence of the pdf $P(\\Delta \\gamma; \\gamma)$ can\nshed important light on plasticity and yield. We conclude that the pdf's of\nboth $\\Delta \\gamma$ and $\\lambda$ are not continuous functions of $\\gamma$. In\nslowly quenched amorphous solids they undergo two discontinuous transitions,\nfirst at $\\gamma=0^+$ and then at the yield point $\\gamma=\\gamma_{_{\\rm Y}}$ to\nplastic flow. In quickly quenched amorphous solids the second transition is\nsmeared out due to the non existing stress peak before yield. The nature of\nthese transitions and scaling relations with the system size dependence of\n$\\langle \\Delta \\gamma\\rangle$ are discussed.",
        "positive": "Connecting active and passive microrheology in living cells: We use a model based on the fractional Langevin equation with external noise\nto describe the anomalous dynamics observed in microrheology experiments in\nliving cells. This model reproduces both the subdiffusive short-time and the\nsuperdiffusive long-time behavior. We show that the former reflects the\nequilibrium properties of the cell, while the latter is due to the\nnonequilibrium external noise. This allows to infer the transport properties of\nthe system under active measurements from the transient behavior obtained from\npassive measurements, extending the connection between active and passive\nmicrorheology to the nonequilibrium regime. The active and passive results can\nbe linked via a generalized Stokes-Einstein relation based on an effective\ntime-dependent temperature, which can be determined from the transient passive\nbehavior. In order to reproduce experimental data, we further find that the\nexternal noise describing the active components of the cell has to be\nnonstationary. We establish that the latter leads to a time-dependent noise\nspectral density."
    },
    {
        "anchor": "Anisotropic Characteristic Lengths of Colloidal Monolayers Near a\n  Water-Air Interface: Near-interface colloidal monolayers have often been used as model systems for\nresearch on hydrodynamics in biophysics and microfluidic systems. Using optical\nmicroscopy and multiparticle tracking techniques, the correlated diffusion of\nparticles is experimentally measured in colloidal monolayers near a water-air\ninterface. It is found that the characteristic lengths X1 and X2 of such a\ncolloidal monolayer are anisotropic in these two perpendicular directions. The\nformer (X1)is equal to the Saffman length of the monolayer and reflects the\ncontinuous nature of the system in the longitudinal direction. The latter\n(X2)is a function of both the Saffman length and the radius of the colloids and\nreflects the discrete nature of the system in the transverse direction. This\ndiscovery demonstrates that the hydrodynamics intrinsically follow different\nrules in these two directions in this system.",
        "positive": "Light-induced pitch transitions in photosensitive cholesteric liquid\n  crystals: Effects of anchoring energy: We experimentally study how the cholesteric pitch, $P$, depends on the\nequilibrium one, $P_0$, in planar liquid crystal (LC) cells with both strong\nand semistrong anchoring conditions. The cholesteric phase was induced by\ndissolution in the nematic LC the right-handed chiral dopant 7-DHC\n(7-dehydrocholesterol, provitamin $D_3$) which transforms to left-handed\ntachysterol under the action of UV irradiation at the wavelength of 254 nm. By\nusing the model of photoreaction kinetics we obtain dependencies of isomers\nconcentrations and thus the equilibrium pitch on UV irradiation dose. The\ncholesteric pitch was measured as a function of irradiation time using the\npolarimetry method. In this method, the pitch is estimated from the\nexperimental data on the irradiation time dependence of the ellipticity of\nlight transmitted through the LC cells. It is found that the resulting\ndependence of the twist parameter, $2 D/P$ ($D$ is the cell thickness), on the\nfree twisting number parameter, $2 D/P_0$, shows the jump-like behaviour and\nagrees well with the known theoretical results for the anchoring potential of\nthe Rapini-Papoular form."
    },
    {
        "anchor": "Phases and homogeneous ordered states in alignment-based self-propelled\n  particle models: We study a set of models of self-propelled particles that achieve collective\nmotion through similar alignment-based dynamics, considering versions with and\nwithout repulsive interactions that do not affect the heading directions. We\nexplore their phase space within a broad range of values of two nondimensional\nparameters (coupling strength and Peclet number), characterizing their\npolarization and degree of clustering. The resulting phase diagrams display\nequivalent, similarly distributed regions for all models with repulsion. The\ndiagrams without repulsion exhibit differences, in particular for high coupling\nstrengths. We compare the boundaries and representative states of all regions,\nidentifying various regimes that had not been previously characterized. We\nanalyze in detail three types of homogeneous polarized states, comparing them\nto existing theoretical and numerical results by computing their velocity and\ndensity correlations, giant number fluctuations, and local order-density\ncoupling. We find that they all deviate in one way or another from the\ntheoretical predictions, attributing these differences either to the remaining\ninhomogeneities or to finite-size effects. We discuss our results in terms of\nthe universal or specific features of each model, their thermodynamic limit,\nand the high mixing and low mixing regimes. Our study provides a broad,\noverarching perspective on the multiple phases and states found in\nalignment-based self-propelled particle models.",
        "positive": "Theory of Aging in Structural Glasses: The random first order transition theory of the dynamics of supercooled\nliquids is extended to treat aging phenomena in nonequilibrium structural\nglasses. A reformulation of the idea of ``entropic droplets'' in terms of\nlibraries of local energy landscapes is introduced which treats in a uniform\nway the supercooled liquid (reproducing earlier results) and glassy regimes.\nThe resulting microscopic theory of aging makes contact with the\nNayaranaswamy-Moynihan-Tool nonlinear relaxation formalism and the\nHodge-Scherer extrapolation of the Adam-Gibbs formula, but deviations from both\napproaches are predicted and shown to be consistent with experiment. The\nnonlinearity of glassy relaxation is shown to quantitatively correlate with\nliquid fragility. The residual nonArrhenius temperature dependence of\nrelaxation observed in quenched glasses is explained. The broadening of\nrelaxation spectra in the nonequilibrium glass with decreasing temperature is\nquantitatively predicted. The theory leads to the prediction of spatially\nfluctuating fictive temperatures in the long-aged glassy state, which have\nnon-Gaussian statistics. This can give rise to ``ultra-slow'' relaxations in\nsystems after deep quenches."
    },
    {
        "anchor": "Photoassociative Frequency Shift in a Quantum Degenerate Gas: We observe a light-induced frequency shift in single-photon photoassociative\nspectra of magnetically trapped, quantum degenerate 7Li. The shift is a\nmanifestation of the coupling between the threshold continuum scattering states\nand discrete bound levels in the excited-state molecular potential induced by\nthe photoassociation laser. The frequency shift is observed to be linear in the\nlaser intensity with a measured proportionality constant that is in good\nagreement with theoretical predictions. The frequency shift has important\nimplications for a scheme to alter the interactions between atoms in a\nBose-Einstein condensate using photoassociation resonances.",
        "positive": "Director alignment at the nematic-isotropic interface: elastic\n  anisotropy and active anchoring: Activity in nematics drives interfacial flows that lead to preferential\nalignment that is tangential or planar for extensile systems (pushers) and\nperpendicular or homeotropic for contractile ones (pullers). This alignment is\nknown as active anchoring and has been reported for a number of systems and\ndescribed using active nematic hydrodynamic theories. The latter are based on\nthe one-elastic constant approximation, i.e., they assume elastic isotropy of\nthe underlying passive nematic. Real nematics, however, have different elastic\nconstants, which lead to interfacial anchoring. In this paper, we consider\nelastic anisotropy in multiphase and multicomponent hydrodynamic models of\nactive nematics and investigate the competition between the interfacial\nalignment driven by the elastic anisotropy of the passive nematic and the\nactive anchoring. We start by considering systems with translational invariance\nto analyze the alignment at flat interfaces and, then, consider two-dimensional\nsystems and active nematic droplets. We investigate the competition of the two\ntypes of anchoring over a wide range of the other parameters that characterize\nthe system. The results of the simulations reveal that the active anchoring\ndominates except at very low activities, when the interfaces are static. In\naddition, we found that the elastic anisotropy does not affect the dynamics but\nchanges the active length that becomes anisotropic."
    },
    {
        "anchor": "Analysis of the velocity field of granular hopper flow: We report the analysis of radial characteristics of the flow of granular\nmaterial through a conical hopper. The discharge is simulated for various\norifice sizes and hopper opening angles. Velocity profiles are measured along\ntwo radial lines from the hopper cone vertex: along the main axis of the cone\nand along its wall. An approximate power law dependence on the distance from\nthe orifice is observed for both profiles, although differences between them\ncan be noted. In order to quantify these differences, we propose a Local Mass\nFlow index that is a promising tool in the direction of a more reliable\nclassification of the flow regimes in hoppers.",
        "positive": "Freezing in polyampholyte globules: Influence of the long-range nature\n  of the interaction: In random heteropolymer globules with short-range interactions between the\nmonomers, freezing takes place at the microscopic length scale only, and can be\ndescribed by a 1-step replica symmetry breaking. The fact that the long-range\nCoulomb interaction has no intrinsic length scale suggests that freezing in\nrandom polyampholyte globules might take place at all length scales,\ncorresponding to an overlap parameter q(x) that increases continuously from\nzero to its maximum value. Study of the polyampholyte globule within the\nindependent interaction approximation seems to confirm this scenario. However,\nthe independent interaction model has an important deficiency: it cannot\naccount for self-screening, and we show that the model is only reliable at\nlength scales shorter than the self-screening length. Using the more realistic\nsequence model we prove that in the general case of a random heteropolymer\nglobule containing two types of monomers such that unlike monomers attract each\nother, freezing at arbitrarily large length scales is not possible. For\npolyampholyte globules this implies that beyond the self-screening length, the\nfreezing behavior is qualitatively the same as in the case of short-range\ninteractions. We find that if the polyampholyte globule is not maximally\ncompact, the degree of frustration is insufficient to obtain freezing."
    },
    {
        "anchor": "Yukawa potentials in systems with partial periodic boundary conditions I\n  : Ewald sums for quasi-two dimensional systems: Yukawa potentials are often used as effective potentials for systems as\ncolloids, plasmas, etc. When the Debye screening length is large, the Yukawa\npotential tends to the non-screened Coulomb potential ; in this small screening\nlimit, or Coulomb limit, the potential is long ranged. As it is well known in\ncomputer simulation, a simple truncation of the long ranged potential and the\nminimum image convention are insufficient to obtain accurate numerical data on\nsystems. The Ewald method for bulk systems, i.e. with periodic boundary\nconditions in all three directions of the space, has already been derived for\nYukawa potential [cf. Y., Rosenfeld, {\\it Mol. Phys.}, \\bm{88}, 1357, (1996)\nand G., Salin and J.-M., Caillol, {\\it J. Chem. Phys.}, \\bm{113}, 10459,\n(2000)], but for systems with partial periodic boundary conditions, the Ewald\nsums have only recently been obtained [M., Mazars, {\\it J. Chem. Phys.}, {\\bf\n126}, 056101 (2007)]. In this paper, we provide a closed derivation of the\nEwald sums for Yukawa potentials in systems with periodic boundary conditions\nin only two directions and for any value of the Debye length. A special\nattention is paid to the Coulomb limit and its relation with the\nelectroneutrality of systems.",
        "positive": "Polar Fluctuations Lead to Extensile Nematic Behavior in Confluent\n  Tissues: How can a collection of motile cells, each generating contractile nematic\nstresses in isolation, become an extensile nematic at the tissue-level?\nUnderstanding this seemingly contradictory experimental observation, which\noccurs irrespective of whether the tissue is in the liquid or solid states, is\nnot only crucial to our understanding of diverse biological processes, but is\nalso of fundamental interest to soft matter and many-body physics. Here, we\nresolve this cellular to tissue level disconnect in the small fluctuation\nregime by using analytical theories based on hydrodynamic descriptions of\nconfluent tissues, in both liquid and solid states. Specifically, we show that\na collection of microscopic constituents with no inherently nematic extensile\nforces can exhibit active extensile nematic behavior when subject to polar\nfluctuating forces. We further support our findings by performing cell level\nsimulations of minimal models of confluent tissues."
    },
    {
        "anchor": "History-dependent deformation of a rotated granular pile governed by\n  granular friction: We experimentally examined the history dependence of the rotation-induced\ngranular deformation. As an initial state, we prepared a quasi-two-dimensional\ngranular pile whose apex is at the rotational axis and its initial inclination\nis at the angle of repose. The rotation rate was increased from $0$ to\n$620$~(rpm) and then decreased back to $0$. During the rotation, deformation of\nthe rotated granular pile was captured by a camera. From the acquired image\ndata, granular friction coefficient $\\mu$ was measured as a function of the\nratio between centrifugal force and gravity, $\\Gamma$. To systematically\nevaluate the variation of $\\mu$ both in the increasing (spinning up) and\ndecreasing (spinning down) rotation-rate regimes, surface profiles of the\ndeformed granular piles were fitted to a model considering the force balance\namong gravity, friction, and centrifugal force at the surface. We found that\n$\\mu$ value grows in the increasing $\\Gamma$ regime. However, when $\\Gamma$ was\nreduced, $\\mu$ cannot recover its initial value. A part of the\nhistory-dependent behaviors of the rotated granular pile can be understood by\nthe force balance model.",
        "positive": "Multiple-scattering effects on incoherent neutron scattering in glasses\n  and viscous liquids: Incoherent neutron scattering experiments are simulated for simple dynamic\nmodels: a glass (with a smooth distribution of harmonic vibrations) and a\nviscous liquid (described by schematic mode-coupling equations). In most\nsituations multiple scattering has little influence upon spectral\ndistributions, but it completely distorts the wavenumber-dependent amplitudes.\nThis explains an anomaly observed in recent experiments."
    },
    {
        "anchor": "Diffusion regimes in Levy flights with trapping: The diffusion of a walk in the presence of traps is investigated. Different\ndiffusion regimes are obtained considering the magnitude of the fluctuations in\nwaiting times and jump distances. A constant velocity during the jump motion is\nassumed to avoid the divergence of the mean squared displacement. Using the\nlimit theorems of the theory of Levy stable distributions we have provided a\ncharacterization of the different diffusion regimes.",
        "positive": "Equilibrium Clusters in Concentrated Lysozyme Protein Solutions: We have studied the structure of salt-free lysozyme at 293 K and pH 7.8 using\nmolecular simulations and experimental SAXS effective potentials between\nproteins at three volume fractions, 0.012, 0.033, and 0.12. We found that the\nstructure of lysozyme near physiological conditions strongly depends on the\nvolume fraction of proteins. The studied lysozyme solutions are dominated by\nmonomers only for <0.012; for the strong dilution 70% of proteins are in a form\nof monomers. For 0.033 only 20% of proteins do not belong to a cluster. The\nclusters are mainly elongated. For 0.12 almost no individual particles exits,\nand branched, irregular clusters of large extent appear. Our simulation study\nprovides new insight into the formation of equilibrium clusters in charged\nprotein solutions near physiological conditions."
    },
    {
        "anchor": "DNA translocation through nanopores with salt gradients: The role of\n  osmotic flow: Recent experiments of translocation of double stranded DNA through nanopores\n[M. Wanunu \\textit{et al.} Nature Nanotech. {\\bf 5}, 160 (2010)] reveal that\nthe DNA capture rate can be significantly influenced by a salt gradient across\nthe pore. We show that osmotic flow combined with electrophoretic effects can\nquantitatively explain the experimental data on the salt-gradient dependence of\nthe capture rate.",
        "positive": "Density functional approach to elastic properties of three-dimensional\n  dipole-spring models for magnetic gels: Magnetic gels are composite materials, consisting of a polymer matrix and\nembedded magnetic particles. Those are mechanically coupled to each other,\ngiving rise to the magnetostrictive effects as well as to a controllable\noverall elasticity responsive to external magnetic fields. Due to their\ninherent composite and thereby multiscale nature, a theoretical framework\nbridging different levels of description is indispensable for understanding the\nmagnetomechanical properties of magnetic gels. In this study, we extend a\nrecently developed density functional approach from two spatial dimensions to\nmore realistic three-dimensional systems. Along these lines, we connect a\nmesoscopic characterization resolving the discrete structure of the magnetic\nparticles, to macroscopic continuum parameters of magnetic gels. In particular,\nwe incorporate the long-range nature of the magnetic dipole-dipole interaction,\nand consider the approximate incompressibility of the embedding media, and\nrelative rotations with respect to an external magnetic field breaking\nrotational symmetry. We then probe the shape of the model system in its\nreference state, confirming the dependence of magnetostrictive effects on the\nconfiguration of the magnetic particles and on the shape of the considered\nsample. Moreover, calculating the elastic and rotational coefficients on the\nbasis of our mesoscopic approach, we examine how the macroscopic types of\nbehavior are related to the mesoscopic properties. Implications for real\nsystems of random particle configurations are also discussed."
    },
    {
        "anchor": "The \"pure-shear\" fracture test for viscoelastic elastomers and its\n  revelation on Griffith fracture: Strikingly, \"pure-shear\" fracture tests have repeatedly shown that fracture\nnucleation in (common hydrocarbon and other types of) viscoelastic elastomers\noccurs at a critical stretch that is independent of the stretch rate at which\nthe test is carried out. In this Letter, we demonstrate that this remarkable --\nyet overlooked -- experimental finding implies that the Griffith criticality\ncondition that governs nucleation of fracture from large pre-existing cracks in\nviscoelastic elastomers can be written in fact as an expression not in terms of\nan elusive loading-history-dependent critical tearing energy Tc, as ordinarily\ndone, but as one exclusively in terms of the intrinsic fracture energy Gc of\nthe elastomer.",
        "positive": "Self-Consistent Hopping Theory of Activated Relaxation and Diffusion of\n  Dilute Penetrants in Dense Crosslinked Polymer Networks: We generalize and apply a microscopic force-level statistical mechanical\ntheory of the activated dynamics of dilute spherical penetrants in\nglass-forming liquids to study the influence of permanent crosslinking in\npolymer networks on the penetrant relaxation time and diffusivity over a wide\nrange of temperature and crosslink density. Calculations are performed for\nmodel parameters relevant to recent experimental studies of an nm-sized organic\nmolecule diffusing in crosslinked PnBA networks. The theory predicts the\npenetrant alpha relaxation time increases exponentially with the crosslink\nfraction ($f_n$) dependent glass transition temperature, $T_g$, which grows\nroughly linearly with the square root of $f_n$. Moreover, $T_g$ is also found\nto be proportional to a geometric confinement parameter defined as the ratio of\nthe penetrant diameter to the mean network mesh size. The decoupling ratio of\nthe penetrant to polymer Kuhn segment alpha relaxation times displays a complex\nnon-monotonic dependence on crosslink density and temperature that can be well\ncollapsed based on the variable $T_g(f_n)/T$. The microscopic mechanism for\nactivated penetrant relaxation is elucidated and a model for the penetrant\ndiffusion constant that combines activated segmental dynamics and entropic mesh\nconfinement is proposed which results in a significantly stronger suppression\nof mass transport with degree of effective supercooling than predicted for the\npenetrant alpha time. This behavior corresponds to a new polymer network-based\ntype of decoupling of diffusion and relaxation. In contrast to the diffusion of\nlarger nanoparticles in high temperature rubbery networks, our analysis in the\ndeeply supercooled regime suggests that for the penetrants studied the mesh\nconfinement effects are of secondary importance relative to the consequences of\ncrosslink-induced slowing down of glassy activated relaxation."
    },
    {
        "anchor": "Field-controlled dynamics of skyrmions and monopoles: Magnetic monopoles, despite their ongoing experimental search as elementary\nparticles, have inspired the discovery of analogous excitations in condensed\nmatter systems. In chiral condensed matter systems, emergent monopoles are\nresponsible for the onset of transitions between topologically distinct states\nand phases, like in the case of transitions from helical and conical phase to\nA-phase comprising periodic arrays of skyrmions. By combining numerical\nmodeling and optical characterizations, we describe how different geometrical\nconfigurations of skyrmions terminating at monopoles can be realized in liquid\ncrystals and liquid crystal ferromagnets. We demonstrate how such complex\nstructures can be effectively manipulated by external magnetic and electric\nfields. Furthermore, we discuss how our findings may hint at similar dynamics\nin other physical systems, and their potential applications.",
        "positive": "Multiphysics Modeling of Surface Diffusion Coupled with Large\n  Deformation in 3D Solids: We present a comprehensive theoretical and computational model that explores\nthe behavior of a thin hydrated film bonded to a non-hydrated / impermeable\nsoft substrate in the context of surface and bulk elasticity coupled with\nsurface diffusion kinetics. This type of coupling can manifests as an integral\naspect in diverse engineering processes encountered in optical interference\ncoatings, tissue engineering, soft electronics, and can prove important in\ndesign process for the next generation of sensors and actuators, especially as\nthe focus is shifted to systems in smaller lengthscales. The intricate\ninterplay between solvent diffusion and deformation of the film is governed by\nsurface poroelasticity, and the viscoelastic deformation of the substrate.\nWhile existing methodologies offer tools for studying coupled poroelasticity\ninvolving solvent diffusion and network deformation, there exists a gap in\nunderstanding how coupled poroelastic processes occurring in a film attached to\nthe boundary of a highly deformable solid can influence its response. In this\nstudy, we introduce a non-equilibrium thermodynamics formulation encompassing\nthe multiphysical processes of surface poroelasticity and bulk viscoelasticity,\ncomplemented by a corresponding finite element implementation. Our approach\ncaptures the complex dynamics between the finite deformation of the substrate\nand solvent diffusion on the surface. This work contributes valuable insights,\nparticularly in scenarios where the coupling of surface diffusion kinetics and\nsubstrate elasticity is an important design factor."
    },
    {
        "anchor": "Slow fluctuations in enhanced Raman scattering and surface roughness\n  relaxation: We propose an explanation for the recently measured slow fluctuations and\n``blinking'' in the surface enhanced Raman scattering (SERS) spectrum of single\nmolecules adsorbed on a silver colloidal particle. We suggest that these\nfluctuations may be related to the dynamic relaxation of the surface roughness\non the nanometer scale and show that there are two classes of roughness with\nqualitatively different dynamics. The predictions agree with measurements of\nsurface roughness relaxation. Using a theoretical model for the kinetics of\nsurface roughness relaxation in the presence of charges and optical electrical\nfields, we predict that the high-frequency electromagnetic field increases both\nthe effective surface tension and the surface diffusion constant and thus\naccelerates the surface smoothing kinetics and time scale of the Raman\nfluctuations in manner that is linear with the laser power intensity, while the\naddition of salt retards the surface relaxation kinetics and increases the time\nscale of the fluctuations. These predictions are in qualitative agreement with\nthe Raman experiments.",
        "positive": "Receptor-Mediated Endocytosis of a Cylindrical Nanoparticle in the\n  Presence of Cytoskeleton Substrate: Internalization of particles by cells plays a crucial role for adsorbing\nnutrients and fighting infection. Endocytosis is one of the most important\nmechanisms of the particles uptake which encompass multiple pathways. Although\nendocytosis is a complex mechanism involving biochemical signaling and active\nforce generation, the energetic cost associated to the large deformations of\nthe cell membrane wrapping around the foreign particle is an important factor\ncontrolling this process, which can be studied using quantitative physical\nmodels. Of particular interest is the competition between membrane -\ncytoskeleton and membrane - target adhesion. Here, we explore the wrapping of a\nlipid membrane around a long cylindrical object in the presence of a substrate\nmimicking the cytoskeleton. Using discretization of the Helfrich elastic energy\nthat accounts for the membrane bending rigidity and surface tension, we obtain\na wrapping phase diagram as a function of the membrane-cytoskeleton and the\nmembrane-target adhesion energy that includes unwrapped, partially wrapped and\nfully wrapped states. We provide an analytical expression for the boundary\nbetween the different regimes. While the transition to partial wrapping is\nindependent of membrane tension, the transition to full wrapping is very much\ninfluenced by membrane tension. We also show that target wrapping may proceed\nin an asymmetric fashion in the full wrapping regime."
    },
    {
        "anchor": "Spontaneous flow instabilities of active polar fluids in three\n  dimensions: Active polar fluids exhibit spontaneous flow when sufficient active stress is\ngenerated by internal molecular mechanisms. This is also referred to as an\nactive Fr\\'{e}edericksz transition. Experiments have revealed the existence of\ncompeting in-plane and out-of-plane instabilities in three-dimensional active\nmatter. So far, however, a theoretical model reconciling all observations is\nmissing. In particular, the role of boundary conditions in these instabilities\nstill needs to be explained. Here, we characterize the spontaneous flow\ntransition in a symmetry-preserving three-dimensional active Ericksen-Leslie\nmodel, showing that the boundary conditions select the emergent behavior. Using\nnonlinear numerical solutions and linear perturbation analysis, we explain the\nmechanism for both in-plane and out-of-plane instabilities under extensile\nactive stress for perpendicular polarity anchoring at the boundary, whereas\nparallel anchoring only permits in-plane flows under contractile stress or\nout-of-plane wrinkling under extensile stress.",
        "positive": "Flow-induced Density Fluctuation assisted Nucleation in Polyethylene: The nucleation process of polyethylene under quiescent and shear flow\nconditions are comparatively studied with all_atom molecular dynamical\nsimulations. At both conditions, nucleation are demonstrated to be two_step\nprocesses, which, however, proceed via different intermediate orders. Quiescent\nnucleation is assisted by local structure order coupling conformational and\nlocal rotational symmetric orderings, while flow_induced nucleation is promoted\nby density fluctuation, which is a coupling effect of conformational and\norientation orderings. Flow drives the transformation from flexible chains to\nrigid conformational ordered segments and circumvents the entropic penalty,\nwhich is the most peculiar and rate_limited step in polymer crystallization.\nCurrent work suggests that flow accelerates nucleation in orders of magnitude\nis not simply due to flow_induced entropic reduction of melt as early models\nproposed, which is mainly attributed to the different kinetic pathway via\nconformational/orientational ordering_density fluctuation_nucleation."
    },
    {
        "anchor": "Theory of cell membrane interaction with glass: There are three regimes of cell membrane interaction with glass - Tight and\nloose adhesion, separated by repulsion. Explicitly including hydration, this\npaper evaluates the pressure between the surfaces as functions of distance for\nion-correlation and ion-screened electrostatics, and electromagnetic\nfluctuations. The results agree with data for tight adhesion energy (0.5-3 vs\n0.4-4 mJ/m2), detachment pressure (7.9 vs 9 MPa), and peak repulsion (3.4-7.5\nvs 5-10 kPa), also matching the repulsion's distance dependence upon\nrenormalization by steric pressure mainly from undulations.",
        "positive": "Elasticity dominated surface segregation of small molecules in polymer\n  mixtures: We study the phenomenon of migration of the small molecular weight component\nof a binary polymer mixture to the free surface using mean field and\nself-consistent field theories. By proposing a free energy functional that\nincorporates polymer-matrix elasticity explicitly, we compute the migrant\nvolume fraction and show that it decreases significantly as the sample rigidity\nis increased. Estimated values of the bulk modulus suggest that the effect\nshould be observable experimentally for rubber-like materials. This provides a\nsimple way of controlling surface migration in polymer mixtures and can play an\nimportant role in industrial formulations, where surface migration often leads\nto decreased product functionality."
    },
    {
        "anchor": "Stochastic Phase Segregation on Surfaces: Phase separation and coarsening is a phenomenon commonly seen in binary\nphysical and chemical systems that occur in nature. Often times, thermal\nfluctuations, modeled as stochastic noise, are present in the system and the\nphase segregation process occurs on a surface. In this work, the segregation\nprocess is modeled via the Cahn-Hilliard-Cook model, which is a fourth-order\nparabolic stochastic system. Coarsening is analyzed on two sample surfaces: a\nunit sphere and a dumbbell using a variety and a statistical analysis of the\ngrowth rate is performed. The influence of noise level and mobility is also\ninvestigated. It is also shown that a log-normal distribution fits the results\nwell.",
        "positive": "Order and density fluctuations near the boundary in sheared dense\n  suspensions: We introduce a novel approach to reveal ordering fluctuations in sheared\ndense suspensions, using line scanning in a combined rheometer and laser\nscanning confocal microscope. We validate the technique with a moderately dense\nsuspension, observing modest shear-induced ordering and a nearly linear flow\nprofile. At high concentration ($\\phi = 0.55$) and applied stress just below\nshear thickening, we report ordering fluctuations with high temporal\nresolution, and directly measure a decrease in order with distance from the\nsuspension's bottom boundary as well as a direct correlation between order and\nparticle concentration. Higher applied stress produces shear thickening with\nlarge fluctuations in boundary stress which we find are accompanied by dramatic\nfluctuations in suspension flow speeds. The peak flow rates are independent of\ndistance from the suspension boundary, indicating that they likely arise from\ntransient jamming that creates solid-like aggregates of particles moving\ntogether, but only briefly because the high speed fluctuations are interspersed\nwith regions flowing much more slowly, suggesting that shear thickening\nsuspensions possess complex internal structural dynamics, even in relatively\nsimple geometries."
    },
    {
        "anchor": "Langevin dynamics of fluctuation induced first order phase transitions:\n  self consistent Hartree Approximation: The Langevin dynamics of a system exhibiting a Fluctuation Induced First\nOrder Phase Transition is solved within the self consistent Hartree\nApproximation. Competition between interactions at short and long length scales\ngives rise to spatial modulations in the order parameter, like stripes in 2d\nand lamellae in 3d. We show that when the time scale of observation is small\ncompared with the time needed to the formation of modulated structures, the\ndynamics is dominated by a standard ferromagnetic contribution plus a\ncorrection term. However, once these structures are formed, the long time\ndynamics is no longer pure ferromagnetic. After a quench from a disordered\nstate to low temperatures the system develops growing domains of stripes\n(lamellae). Due to the character of the transition, the paramagnetic phase is\nmetastable at all finite temperatures, and the correlation length diverges only\nat T=0. Consequently, the temperature is a relevant variable, for $T>0$ the\nsystem exhibits interrupted aging while for T=0 the system ages for all time\nscales. Furthermore, for all $T$, the exponent associated with the aging\nphenomena is independent of the dimension of the system.",
        "positive": "The problem of a metal impurity in an oxide: ab-initio study of\n  electronic and structural properties of Cd in Rutile TiO2: In this work we undertake the problem of a transition metal impurity in an\noxide. We present an ab-initio study of the relaxations introduced in TiO2 when\na Cd impurity replaces substitutionally a Ti atom. Using the Full-Potential\nLinearized-Augmented-Plane-Wave method we obtain relaxed structures for\ndifferent charge states of the impurity and computed the electric-field\ngradients (EFGs) at the Cd site. We find that EFGs, and also relaxations, are\ndependent on the charge state of the impurity. This dependence is very\nremarkable in the case of the EFG and is explained analyzing the electronic\nstructure of the studied system. We predict fairly anisotropic relaxations for\nthe nearest oxygen neighbors of the Cd impurity. The experimental confirmation\nof this prediction and a brief report of these calculations have recently been\npresented [P.R.L. 89, 55503 (2002)]. Our results for relaxations and EFGs are\nin clear contradiction with previous studies of this system that assumed\nisotropic relaxations and point out that no simple model is viable to describe\nrelaxations and the EFG at Cd in TiO2 even approximately."
    },
    {
        "anchor": "Self assembly of monodisperse CdS nano-cylinders with a pore: We present investigate the self assembly and growth of an array of $CdS$\nnanotubes: a consequence of a fine balance of directed motion, diffusion and\naggregation of reacting ${\\rm Cd^{+2}}$ and ${\\rm S^{-2}}$ ions. In a previous\ncommunication [J. Kiruthiga, A. Chatterji, J. Chem. Phys., {\\bf 138} 024905\n(2013)], we identified the mechanism of a unexpected growth of a very uniform\n$CdS$ nano-cylinder from the end of a nano-channel. Furthermore, the cylinder\nhad a pore along the axis but were closed at one end. This unique phenomenon of\nself assembly of {\\em monodisperse} CdS nano-cylinders had been observed in a\nrather simple experiment where two chambers containing 0.1 M ${\\rm Cd Cl_2}$\nand 0.1 M ${\\rm Na_2 S}$ solutions were joined by an array of anodized\naluminium oxide (AAO) nano-channels [A. Varghese, S. Datta, Phys. Rev. E., {\\bf\n85}, 056104 (2012)]. Our previous study identified the principles governing the\ngrowth of a single nano-tube at the exit point of a single AAO-nano-channel. In\nthis communication, we identify factors affecting the self-assembly process for\nnano-tubes growing out an array of closely spaced AAO nano-channel exits. Our\nmodel is not $Cd^{+2}$ or $S^{2-}$ specific, the experimental scheme can be\nextended to self assemble a general class of reacting-diffusing A and B ions\nwith A (${\\rm Cd^{+2}}$) selectively migrating out from a nano-channel. In\nparticular, we note that after the initial prolonged growth of nanotubes, there\ncan arise a severe deficiency of B-ions (${\\rm S^{-2}}$) ions near the\nAAO-nano-channel exits, the points where the reaction and aggregation occurs to\nform the $CdS$ nanotube, thus impeding further growth of uniform CdS\nnano-tubes. Thereby we predict the necessary characteristics of reacting\nsystems which can be self assembled using suitable adaptations of previous\nexperiments.",
        "positive": "Wrapping of a spherical colloid by a fluid membrane: We theoretically study the elastic deformation of a fluid membrane induced by\nan adhering spherical colloidal particle within the framework of a Helfrich\nenergy. Based on a full optimization of the membrane shape we find a continuous\nbinding and a discontinuous envelopment transition, the latter displaying a\npotentially substantial energy barrier. A small gradient approximation permits\nmembrane shape and complex energy to be calculated analytically. While this\nonly leads to a good representation of the complex geometry for very small\ndegrees of wrapping, it still gives the correct phase boundaries in the regime\nof low tension."
    },
    {
        "anchor": "Two-dimensional flows of foam: drag exerted on circular obstacles and\n  dissipation: A Stokes experiment for foams is proposed. It consists in a two-dimensional\nflow of a foam, confined between a water subphase and a top plate, around a\nfixed circular obstacle. We present systematic measurements of the drag exerted\nby the flowing foam on the obstacle, \\emph{versus} various separately\ncontrolled parameters: flow rate, bubble volume, solution viscosity, obstacle\nsize and boundary conditions. We separate the drag into two contributions, an\nelastic one (yield drag) at vanishing flow rate, and a fluid one (viscous\ncoefficient) increasing with flow rate. We quantify the influence of each\ncontrol parameter on the drag. The results exhibit in particular a power-law\ndependence of the drag as a function of the solution viscosity and the flow\nrate with two different exponents. Moreover, we show that the drag decreases\nwith bubble size, increases with obstacle size, and that the effect of boundary\nconditions is small. Measurements of the streamwise pressure gradient,\nassociated to the dissipation along the flow of foam, are also presented: they\nshow no dependence on the presence of an obstacle, and pressure gradient\ndepends on flow rate, bubble volume and solution viscosity with three\nindependent power laws.",
        "positive": "Avalanche precursors in a frictional model: We present a one-dimensional numerical model based on elastically coupled\nsliders on a frictional incline of variable tilt. This very simple approach\nmakes possible to study the precursors to the avalanche and to provide a\nrationalization of different features that have been observed in experiments.\nWe provide a statistical description of the model leading to master equations\ndescribing the state of the system as a function of the angle of inclination.\nOur central results are the reproduction of large-scale regular events\npreceding the avalanche, on the one hand, and an analytical approach providing\nan internal threshold for the outbreak of rearrangements before the avalanche\nin the system, on the other hand."
    },
    {
        "anchor": "Giant osmotic pressure in the forced wetting of hydrophobic nanopores: The forced intrusion of water in hydrophobic nanoporous pulverulent material\nis of interest for quick storage of energy. With nanometric pores the energy\nstorage capacity is controlled by interfacial phenomena. With subnanometric\npores, we demonstrate that a breakdown occurs with the emergence of molecular\nexclusion as a leading contribution. This bulk exclusion effect leads to an\nosmotic contribution to the pressure that can reach levels never previously\nsustained. We illustrate on various electrolytes and different microporous\nmaterials, that a simple osmotic pressure law accounts quantitatively for the\nenhancement of the intrusion and extrusion pressures governing the forced\nwetting and spontaneous drying of the nanopores. Using electrolyte solutions,\nenergy storage and power capacities can be widely enhanced.",
        "positive": "On the calculation of potential of mean force between atomistic\n  nanoparticles: We study the potential of mean force (PMF) between atomistic silica and gold\nnanoparticles in the vacuum by using molecular dynamics simulations. Such an\ninvestigation is devised in order to fully characterize the effective\ninteractions between atomistic nanoparticles, a crucial step to describe the\nPMF in high-density coarse-grained polymer nanocomposites. In our study, we\nfirst investigate the behavior of silica nanoparticles, considering cases\ncorresponding to different particle sizes and assessing results against an\nanalytic theory developed by Hamaker for a system of Lennard-Jones interacting\nparticles [H. C. Hamaker, Physica A, 1937, 4, 1058]. Once validated the\nprocedure, we calculate effective interactions between gold nanoparticles,\nwhich are considered both bare and coated with polyethylene chains, in order to\ninvestigate the effects of the grafting density \\rho_g on the PMF. Upon\nperforming atomistic molecular dynamics simulations, it turns out that silica\nnanoparticles experience similar interactions regardless of the particle size,\nthe most remarkable difference being a peak in the PMF due to surface\ninteractions, clearly apparent for the larger size. As for bare gold\nnanoparticles, they are slightly interacting, the strength of the effective\nforce increasing for the coated cases. The profile of the resulting PMF\nresembles a Lennard-Jones potentials for intermediate \\rho_g , becoming\nprogressively more repulsive for high \\rho_g and low interparticle separations."
    },
    {
        "anchor": "Reduced heat flow in light water (H2O) due to heavy water (D2O): The flow of heat, from top to bottom, in a column of light water can be\ndecreased by over 1000% with the addition of heavy water. A column of light\nwater cools from 25 C to 0 C in 11 hours, however, with the addition of heavy\nwater it takes more than 100 hours. There is a concentration dependence where\nthe cooling time increases as the concentration of added (D2O) increases, with\na near maximum being reached with as little as 2% of (D2O) added. This\nphenomenon will not occur if the water is mixed after the heavy water is added.",
        "positive": "High-speed discrimination and sorting of sub-micron particles using a\n  microfluidic device: The size- and fluorescence-based sorting of micro- and nano-scale particles\nsuspended in fluid presents a significant and important challenge for both\nsample analysis and for manufacturing of nanoparticle-based products. Here we\ndemonstrate a disposable microfluidic particle sorter that enables\nhigh-throughput, on-demand counting and binary sorting of sub-micron particles\nand cells, using either fluorescence or an electrically-based determination of\nparticle size. Size-based sorting uses a resistive pulse sensor integrated\non-chip, while fluorescence-based discrimination is achieved using on-the-fly\noptical image capture and analysis. Following detection and analysis, the\nindividual particles are deflected using a pair of piezoelectric actuators,\ndirecting the particles into one of two desired output channels; the main flow\ngoes into a third waste channel. The integrated system can achieve sorting\nfidelities of better than 98\\%, and the mechanism can successfully count and\nactuate, on demand, more than 60,000 particles/min."
    },
    {
        "anchor": "Thermalized formulation of soft glassy rheology: We present a version of soft glassy rheology that includes thermalized strain\ndegrees of freedom. It fully specifies systems' strain-history-dependent\npositions on their energy landscapes and therefore allows for quantitative\nanalysis of their heterogeneous yielding dynamics and nonequilibrium\ndeformation thermodynamics. As a demonstration of the method, we illustrate the\nvery different characteristics of fully-thermal and nearly-athermal plasticity\nby comparing results for thermalized and nonthermalized plastic flow.",
        "positive": "Viscous Mechano-Electric Response of Ferroelectric Nematic Liquid: Direct viscous mechano-electric response is demonstrated for a\nroom-temperature ferroelectric nematic liquid, which combines large spontaneous\nelectric polarization with 3D fluidity. The mechano-electric transduction is\nobserved in the frequency range 1-200 Hz via a simple demonstrator device. The\nliquid is placed into a deformable container with electrodes and the electric\ncurrent induced by both periodic and irregular actuation of the container is\nexamined. The experiments reveal a rich interplay of several distinct viscous\nmechano-electric phenomena, where both shape deformations and material flow\ncause changes in the electric polarization structure of a ferroelectric nematic\nliquid. The results show that the mechano-electric features of the material\npromise a considerable applicative perspective spanning from sensitive tactile\nsensors to energy harvesting devices."
    },
    {
        "anchor": "Mechanical properties of acoustically levitated granular rafts: We investigate a model system for the rotational dynamics of inertial\nmany-particle clustering, in which sub-millimeter objects are acoustically\nlevitated in air. Driven by scattered sound, levitated grains self-assemble\ninto a monolayer of particles, forming mesoscopic granular rafts with both an\nacoustic binding energy and a bending rigidity. Detuning the acoustic trap can\ngive rise to stochastic forces and torques that impart angular momentum to\nlevitated objects. As the angular momentum of a quasi-two-dimensional granular\nraft is increased, the raft deforms from a disk to an ellipse, eventually\npinching off into multiple separate rafts, in a mechanism that resembles the\nbreak-up of a liquid drop. We extract the raft effective surface tension and\nelastic modulus, and show that non-pairwise acoustic forces give rise to\neffective elastic moduli that scale with the raft size. We also show that the\nraft size controls the microstructural basis of plastic deformation, resulting\nin a transition from fracture to ductile failure.",
        "positive": "Rain water transport and storage in a model sandy soil with hydrogel\n  particle additives: We study rain water infiltration and drainage in a dry model sandy soil with\nsuperabsorbent hydrogel particle additives by measuring the mass of retained\nwater for non-ponding rainfall using a self-built 3D laboratory set-up. In the\npure model sandy soil, the retained water curve measurements indicate that\ninstead of a stable horizontal wetting front that grows downward uniformly, a\nnarrow fingered flow forms under the top layer of water-saturated soil. This\nrain water channelization phenomenon not only further reduces the available\nrain water in the plant root zone, but also affects the efficiency of soil\nadditives, such as superabsorbent hydrogel particles. Our studies show that the\nshape of the retained water curve for a soil packing with hydrogel particle\nadditives strongly depends on the location and the concentration of the\nhydrogel particles in the model sandy soil. By carefully choosing the particle\nsize and distribution methods, we may use the swollen hydrogel particles to\nmodify the soil pore structure, to clog or extend the water channels in sandy\nsoils, or to build water reservoirs in the plant root zone."
    },
    {
        "anchor": "Tissue fluidization by cell-shape-controlled active stresses: Biological cells can actively tune their intracellular architecture according\nto their overall shape. Here we explore the rheological implication of such\ncoupling in a minimal model of a dense cellular material where each cell exerts\nan active mechanical stress along its axis of elongation. Increasing the active\nstress amplitude leads to several transitions. An initially hexagonal crystal\nmotif is first destabilized into a solid with anisotropic cells. Increasing\nactivity further, we find a re-entrant transition to a regime with finite\nhexatic order and finite shear modulus, in which cells arrange according to a\nrhombile pattern with periodically arranged rosette structures. The shear\nmodulus vanishes again at a third threshold beyond which spontaneous tissue\nflows arise. In this last regime, we observe the emergence of cell shape\npatterns called topological defects, with flow and stress fields around defects\nagreeing with those observed in epithelial tissue experiments. We further\nprovide a testable prediction of cell-cell rearrangement hotspots near\ntopological defects. Overall, our work connects seemingly distinct features -\ne.g. rosettes and topological defects - observed across various types of\nepithelial tissues.",
        "positive": "A review of Monte Carlo simulations of polymers with PERM: In this review, we describe applications of the pruned-enriched Rosenbluth\nmethod (PERM), a sequential Monte Carlo algorithm with resampling, to various\nproblems in polymer physics. PERM produces samples according to any given\nprescribed weight distribution, by growing configurations step by step with\ncontrolled bias, and correcting \"bad\" configurations by \"population control\".\nThe latter is implemented, in contrast to other population based algorithms\nlike e.g. genetic algorithms, by depth-first recursion which avoids storing all\nmembers of the population at the same time in computer memory. The problems we\ndiscuss all concern single polymers (with one exception), but under various\nconditions: Homopolymers in good solvents and at the $\\Theta$ point, semi-stiff\npolymers, polymers in confining geometries, stretched polymers undergoing a\nforced globule-linear transition, star polymers, bottle brushes, lattice\nanimals as a model for randomly branched polymers, DNA melting, and finally --\nas the only system at low temperatures, lattice heteropolymers as simple models\nfor protein folding. PERM is for some of these problems the method of choice,\nbut it can also fail. We discuss how to recognize when a result is reliable,\nand we discuss also some types of bias that can be crucial in guiding the\ngrowth into the right directions."
    },
    {
        "anchor": "Coulomb interaction effects on nonlinear optical response in C60, C70,\n  and higher fullerenes: Nonlinear optical properties in the fullerene C$_{60}$ and the extracted\nhigher fullerenes -- C$_{70}$, C$_{76}$, C$_{78}$, and C$_{84}$ -- are\ntheoretically investigated by using the exciton formalism and the\nsum-over-states method. We find that off-resonant third order susceptibilities\nof higher fullerenes are a few times larger than those of C$_{60}$. The\nmagnitude of nonlinearity increases as the optical gap decreases in higher\nfullerenes. The nonlinearity is nearly proportional to the fourth power of the\ncarbon number when the onsite Coulomb repulsion is $2t$ or $4t$, $t$ being the\nnearest neighbor hopping integral. This result, indicating important roles of\nCoulomb interactions, agrees with quantum chemical calculations of higher\nfullerenes.",
        "positive": "How Interactions Control Molecular Transport in Channels: The motion of molecules across channels is critically important for\nunderstanding mechanisms of cellular processes. Here we investigate the\nmechanism of interactions in the molecular transport by analyzing exactly\nsolvable discrete stochastic models. It is shown that the strength and spatial\ndistribution of molecule/channel interactions can strongly modify the particle\ncurrent. Our analysis indicates that the most optimal transport is achieved\nwhen the binding sites are near the entrance or exit of the pore. In addition,\nthe role of intermolecular interactions is studied, and it is argued that an\nincrease in flux can be observed for some optimal interaction strength. The\nmechanism of these phenomena is discussed."
    },
    {
        "anchor": "Water Assisted Proton Transport in Confined Nanochannels: Hydrated excess protons under hydrophobic confinement are a critical\ncomponent of charge transport behavior and reactivity in nanoporous materials\nand biomolecular systems. Herein excess proton confinement effects are\ncomputationally investigated for sub-2 nm hydrophobic nanopores by varying the\ndiameters (d = 0.81, 0.95, 1.09, 1.22, 1.36, 1.63, and 1.90 nm), lengths (l ~3\nand ~5 nm), curvature, and chirality of cylindrical carbon nanotube (CNT)\nnanopores. CNTs with a combination of different diameter segments are also\nexplored. The spatial distribution of water molecules under confinement are\ndiameter-dependent; however, proton solvation and transport is consistently\nfound to occur in the water layer adjacent to the pore wall, showing an\n\"amphiphilic\" character of the hydrated excess proton hydronium-like structure.\nThe proton transport free energy barrier also decreases significantly as the\nnanopore diameter increases and proton transport becomes almost barrierless in\nthe d > 1 nm nanopores. Among the nanopores studied, the Zundel cation\n(${H_{5}O_{2}}^{+}$) is populated only in the d = 0.95 nm CNT (7,7) nanopore.\nThe presence of the hydrated excess proton and $K^{+}$ inside the CNT (7,7)\nnanopore induces a water density increase by 40 and 20%, respectively. The\n$K^{+}$ transport through CNT nanopores is also consistently higher in free\nenergy barrier than proton transport. Interestingly, the evolution of excess\nprotonic charge defect distribution reveals a \"frozen\" single water wire\nconfiguration in the d = 0.81 nm CNT (6,6) nanopore (or segment), through which\nhydrated excess protons can only shuttle via the Grotthuss mechanism. Vehicular\ndiffusion becomes relevant to proton transport in the \"flat\" free energy\nregions and in the wider nanopores, where protons do not primarily shuttle in\nthe axial direction.",
        "positive": "Optimal face-to-face coupling for fast self-folding kirigami: Kirigami-inspired designs can enable self-folding three-dimensional materials\nfrom flat, two-dimensional sheets. Hierarchical designs of connected levels\nincrease the diversity of possible target structures, yet they can lead to\nlonger folding times in the presence of fluctuations. Here, we study the effect\nof rotational coupling between levels on the self-folding of two-level kirigami\ndesigns driven by thermal noise in a fluid. Naturally present due to\nhydrodynamic resistance, we find that optimization of this coupling as control\nparameter can significantly improve a structure's self-folding rate and yield."
    },
    {
        "anchor": "Local Structure Analysis in $Ab$ $Initio$ Liquid Water: Within the framework of density functional theory, the inclusion of exact\nexchange and non-local van der Waals/dispersion (vdW) interactions is crucial\nfor predicting a microscopic structure of ambient liquid water that\nquantitatively agrees with experiment. In this work, we have used the local\nstructure index (LSI) order parameter to analyze the local structure in such\nhighly accurate $ab$ $initio$ liquid water. At ambient conditions, the LSI\nprobability distribution, P($I$), was unimodal with most water molecules\ncharacterized by more disordered high-density-like local environments. With\nthermal excitations removed, the resultant bimodal P($I$) in the inherent\npotential energy surface (IPES) exhibited a 3:1 ratio between high- and\nlow-density-like molecules, with the latter forming small connected clusters\namid the predominant population. By considering the spatial correlations and\nhydrogen bond network topologies $among$ water molecules with the same LSI\nidentities, we demonstrate that the signatures of the experimentally observed\nlow- (LDA) and high-density (HDA) amorphous phases of ice are present in the\nIPES of ambient liquid water. Analysis of the LSI autocorrelation function\nuncovered a persistence time of $\\sim$ 4 ps---a finding consistent with the\nfact that natural thermal fluctuations are responsible for transitions between\nthese distinct yet transient local aqueous environments in ambient liquid\nwater.",
        "positive": "Structure and transport properties of poly(ethylene oxide) based\n  cross-linked polymer electrolytes -- A Molecular Dynamics Simulations study: We present an extensive molecular dynamics (MD) simulation study of\npoly(ethylene oxide) (PEO) based densely cross-linked polymers, focussing on\nstructural properties as well as the systems dynamics in the presence of\nlithium salt. Motivated by experimental findings for networks with short PEO\nstrands we employ a combination of LiTFSI (Lithium\nbis(trifluoromethanesulfonyl)imide) and LiDFOB (Lithium\ndifluoro(oxalato)borate). Recently, it has been shown that such multi-salt\nsystems outperform classical single salt systems (Shaji et al., Energy Storage\nMaterials, 2022, 44, 263). To analyse the microscopic scenario we employ an\nanalytical model, originally developed for non-cross-linked polymer\nelectrolytes or blends (Maitra et al., Phys. Rev. Lett., 2007, 98, 227802 and\nDiddens et al., J. Electrochem. Soc., 2017, 164, E3225-E3231). Excluding very\nshort PEO strands, the local dynamics is only slightly restricted compared to\nlinear PEO and is not significantly dependent on the network structure. The\ntransfer of lithium ions between PEO chains and the motion along the polymer\nbackbone may be controlled through the employed salt."
    },
    {
        "anchor": "Fluid-crystal coexistence for proteins and inorganic nanocolloids:\n  dependence on ionic strength: We investigate theoretically the fluid-crystal coexistence of solutions of\nglobular charged nanoparticles like proteins and inorganic colloids. The\nthermodynamic properties of the fluid phase are computed via the optimized\nBaxter model. This is done specifically for lysozyme and silicotungstates for\nwhich the bare adhesion parameters are evaluated via the experimental second\nvirial coefficients. The electrostatic free energy of the crystal is\napproximated by supposing the cavities in the interstitial phase between the\nparticles are spherical in form. In the salt-free case a Poisson-Boltzmann\nequation is solved to calculate the effective charge on a particle and a Donnan\napproximation is used to derive the chemical potential and osmotic pressure in\nthe presence of salt. The coexistence data of lysozyme and silicotungstates are\nanalyzed within this scheme, especially with regard to the ionic-strength\ndependence of the chemical potentials. The latter agree within the two phases\nprovided some upward adjustment of the effective charge is allowed for.",
        "positive": "Conformational phase diagram for polymers adsorbed at ultrathin\n  nanowires: We study the conformational behavior of a polymer adsorbed at an attractive\nnanostring and construct the complete structural phase diagram in dependence of\nthe binding strength and effective thickness of the string. For this purpose,\nMonte Carlo optimization techniques are employed to identify lowest-energy\nstructures for a coarse-grained hybrid polymer-wire model. Among the\nrepresentative conformations in the different phases are, for example, compact\ndroplets attached to the string and also nanotube-like monolayer films wrapping\nthe string in a very ordered way. We here systematically analyze low-energy\nshapes and structural order parameters to elucidate the transitions between the\nstructural phases."
    },
    {
        "anchor": "Size separation in vibrated granular matter: We review recent developments in size separation in vibrated granular\nmaterials. Motivated by a need in industry to efficiently handle granular\nmaterials and a desire to make fundamental advances in non-equilibrium physics,\nexperimental and theoretical investigations have shown size separation to be a\ncomplex phenomena. Large particles in a vibrated granular system invariably\nrise to the top. However, they may also sink to the bottom, or show other\npatterns depending on subtle variations in physical conditions. While size\nratio is a dominant factor, particle specific properties such as density,\ninelasticity and friction can play an important role. The nature of the energy\ninput, boundary conditions and interstitial air have been also shown to be\nsignificant factors in determining spatial distributions. The presence of\nconvection can enhance mixing or lead to size separation. Experimental\ntechniques including direct visualization and magnetic resonance imaging are\nbeing used to investigate these properties. Molecular dynamics and Monte Carlo\nsimulation techniques have been developed to probe size separation. Analytical\nmethods such as kinetic theory are being used to study the interplay between\nparticle size and density in the vibro-fluidized regime, and geometric models\nhave been proposed to describe size separation for deep beds. Besides\ndiscussing these studies, we will also review the impact of inelastic collision\nand friction on the density and velocity distributions to gain a deeper\nappreciation of the non-equilibrium nature of the system. While a substantial\nnumber of studies have been accomplished, considerable work is still required\nto achieve a firm description of the phenomena.",
        "positive": "Glassy Dynamics of Simulated Polymer Melts: Coherent Scattering and Van\n  Hove Correlation Functions Part I: Dynamics in the beta-Relaxation Regime: We report results of molecular-dynamics simulations of a model polymer melt\nconsisting of short non-entangled chains in the supercooled state above the\ncritical temperature of mode-coupling theory (MCT). To analyse the dynamics of\nthe system we computed the incoherent, collective chain and melt intermediate\nscattering functions as well as the Van Hove correlation functions. We find\ngood evidence for the space-time factorization theorem of MCT. From the\ncritical amplitudes we could derive typical length scales of the beta-dyamics.\nIn an extensive quantitative analysis the leading order description of MCT was\nfound to be accurate in the central beta-regime. Higher order corrections\nextend the validity of the MCT approximation to a greater time window.\nIndications of polymer specific effects on the length scale of the chain's\nradius of gyration are visible in the beta-coefficients."
    },
    {
        "anchor": "Diffusion coefficients in leaflets of bilayer membranes: We study diffusion coefficients of liquid domains by explicitly taking into\naccount the two-layered structure called leaflets of the bilayer membrane. In\ngeneral, the velocity fields associated with each leaflet are different and the\nlayers sliding past each other cause frictional coupling. We obtain analytical\nresults of diffusion coefficients for a circular liquid domain in a leaflet,\nand quantitatively study their dependence on the inter-leaflet friction. We\nalso show that the diffusion coefficients diverge in the absence of coupling\nbetween the bilayer and solvents, even when the inter-leaflet friction is taken\ninto account. In order to corroborate our theory, the effect of the\ninter-leaflet friction on the correlated diffusion is examined.",
        "positive": "Depleting states dictate the ideal glass and physics of glass transition: Understanding the properties of supercooled fluids in equilibrium, even below\nthe calorimetric glass transition $T_g$, is an elusive challenge. This is even\nmore true for the properties of the ideal glass, defined as the minimum of the\npotential energy landscape (PEL) in the non-crystalline regime. Although its\nexistence is a mathematical necessity due to the finite range of energies, its\nproperties, and physical relevance are still undecided. Here we combine the\nmillion-fold acceleration of Swap Monte Carlo with PEL analysis to study a\nnon-network 2D model glass former in equilibrium for a wide range of system\nsizes and temperatures. We observe the transition from fragile to strong\nbehavior and provide a generic perspective to such observations in many\nexperimental non-network glass formers, or the saturation of structural\ndisorder upon cooling. Furthermore, we can identify a particular system size\nthat shows quantitative agreement with the macroscopic limit, while allowing a\ncomplete characterization of the potential energy landscape (PEL) down to its\nglobal minimum. This implies the availability of configurational entropy down\nto the zero temperature limit without the detour via liquid entropy, thereby\nquantifying the putative entropy crisis. Through appropriate system size\nanalysis, we can identify a low-energy depletion regime, including the ideal\nglass, and reveal its physical relevance for equilibrium properties over a wide\ntemperature range, including below $T_g$."
    },
    {
        "anchor": "Attempted density blowup in a freely cooling dilute granular gas:\n  hydrodynamics versus molecular dynamics: It has been recently shown (Fouxon et al. 2007) that, in the framework of\nideal granular hydrodynamics (IGHD), an initially smooth hydrodynamic flow of a\ngranular gas can produce an infinite gas density in a finite time. Exact\nsolutions that exhibit this property have been derived. Close to the\nsingularity, the granular gas pressure is finite and almost constant. This work\nreports molecular dynamics (MD) simulations of a freely cooling gas of nearly\nelastically colliding hard disks, aimed at identifying the \"attempted\" density\nblowup regime. The initial conditions of the simulated flow mimic those of one\nparticular solution of the IGHD equations that exhibits the density blowup. We\nmeasure the hydrodynamic fields in the MD simulations and compare them with\npredictions from the ideal theory. We find a remarkable quantitative agreement\nbetween the two over an extended time interval, proving the existence of the\nattempted blowup regime. As the attempted singularity is approached, the\nhydrodynamic fields, as observed in the MD simulations, deviate from the\npredictions of the ideal solution. To investigate the mechanism of breakdown of\nthe ideal theory near the singularity, we extend the hydrodynamic theory by\naccounting separately for the gradient-dependent transport and for finite\ndensity corrections.",
        "positive": "Dynamic structure factor of a Bose Einstein condensate in a 1D optical\n  lattice: We study the effect of a one dimensional periodic potential on the dynamic\nstructure factor of an interacting Bose Einstein condensate at zero\ntemperature. We show that, due to phononic correlations, the excitation\nstrength towards the first band develops a typical oscillating behaviour as a\nfunction of the momentum transfer, and vanishes at even multiples of the Bragg\nmomentum. The effects of interactions on the static structure factor are found\nto be significantly amplified by the presence of the optical potential. Our\npredictions can be tested in stimulated photon scattering experiments."
    },
    {
        "anchor": "Twist-Stretch Elasticity of DNA: The symmetries of the DNA double helix require a new term in its linear\nresponse to stress: the coupling between twist and stretch. Recent experiments\nwith torsionally-constrained single molecules give the first direct measurement\nof this important material parameter. We extract its value from a recent\nexperiment of Strick, et al. and find rough agreement with an independent\nexperimental estimate recently given by Marko. We also present a very simple\nmicroscopic theory predicting a value comparable to the one observed.",
        "positive": "Order and Information in the Patterns of Spinning Magnetic Micro-disks\n  at the Air-water Interface: The application of the Shannon entropy to study the relationship between\ninformation and structures has yielded insights into molecular and material\nsystems. However, the difficulty in directly observing and manipulating atoms\nand molecules hampers the ability of these systems to serve as model systems\nfor further exploring the links between information and structures. Here, we\nuse, as a model experimental system, hundreds of spinning magnetic micro-disks\nself-organizing at the air-water interface to generate various spatiotemporal\npatterns with varying degrees of orders. Using the neighbor distance as the\ninformation-bearing variable, we demonstrate the links among information,\nstructure, and interactions. Most importantly, we establish a direct link\nbetween information and structure without using explicit knowledge of\ninteractions. Finally, we show that the Shannon entropy by neighbor distances\nis a powerful observable in characterizing structural changes. Our findings are\nrelevant for analyzing natural self-organizing systems and for designing\ncollective robots."
    },
    {
        "anchor": "Fluctuations of local electric field and dipole moments in water between\n  metal walls: We examine the thermal fluctuations of the local electric field $E_k^{\\rm\nloc}$ and the dipole moment $\\mu_k$ in liquid water at $T=298$ K between metal\nwalls in electric field applied in the perpendicular direction. We use analytic\ntheory and molecular dynamics simulation. In this situation, there is a global\nelectrostatic coupling between the surface charges on the walls and the\npolarization in the bulk. Then, the correlation function of the polarization\ndensity $p_z(r)$ along the applied field contains a homogeneous part inversely\nproportional to the cell volume $V$. Accounting for the long-range dipolar\ninteraction, we derive the Kirkwood-Fr$\\ddot{\\rm{o}}$hlich formula for the\npolarization fluctuations when the specimen volume $v$ is much smaller than\n$V$. However, for not small $v/V$, the homogeneous part comes into play in\ndielectric relations. We also calculate the distribution of $E_k^{\\rm loc}$ in\napplied field. As a unique feature of water, its magnitude $|E_k^{\\rm loc}|$\nobeys a Gaussian distribution with a large mean value $E_0 \\cong 17~$V$/$nm,\nwhich arises mainly from the surrounding hydrogen-bonded molecules. Since\n$|\\mu_k|E_0\\sim 30 k_{\\rm B}T$, $\\mu_k$ becomes mostly parallel to $E_k^{\\rm\nloc}$. As a result, the orientation distributions of these two vectors nearly\ncoincide, assuming the classical exponential form. In dynamics, the component\nof $\\mu_k(t)$ parallel to $E_k^{\\rm loc}(t)$ changes on the timescale of the\nhydrogen bonds $\\sim 5$ ps, while its smaller perpendicular component undergoes\nlibrational motions on timescales of 0.01 ps.",
        "positive": "Modeling the temperature of maximum density of aqueous tert-butanol\n  solutions: Short-chain alcohols at high dilution are among the very few solutes that\nenhance the anomalous behavior of water, in particular the value of the\ntemperature of maximum density. This peculiar feature, first discovered\nexperimentally in the early sixties, has remained elusive to a full explanation\nin terms of atomistic models. In this paper, we first introduce a two-site\nmodel of tert-butanol in which the interactions involving hydrogen bonding are\nrepresented by a Stillinger-Weber potential, following the ideas first\nintroduced by Molinero and Moore, [J. Phys. Chem. B, 113, 4008, (2009)]. Our\nmodel parameters are fit so as to semi-quantitatively reproduce the\nexperimental densities and vaporization enthalpies of previously proposed\nunited atom and all atom OPLS models. Water is represented using the\naforementioned potential model introduced by Molinero and Moore, with cross\ninteraction parameters between water and tert-butanol optimized to yield a\nreasonable description of the experimental excess enthalpies and volumes over\nthe whole composition range of the mixture. We will see that our simple model\nis able to reproduce the presence of a maximum in the change of the temperature\nof maximum density for very low alcohol mole fractions, followed by a\nconsiderable decrease until the density anomaly itself disappears. We have\ncorrelated this behavior with changes in the local structure of water and\ncompared it with the results of all-atom simulations of water/tert-butanol\nmixtures."
    },
    {
        "anchor": "Electrode Polarization Effects in Broadband Dielectric Spectroscopy: In the present work, we provide broadband dielectric spectra showing strong\nelectrode polarization effects for various materials, belonging to very\ndifferent material classes. This includes both ionic and electronic conductors\nas, e.g., salt solutions, ionic liquids, human blood, and\ncolossal-dielectric-constant materials. These data are intended to provide a\nbroad data base enabling a critical test of the validity of phenomenological\nand microscopic models for electrode polarization. In the present work, the\nresults are analyzed using a simple phenomenological equivalent-circuit\ndescription, involving a distributed parallel RC circuit element for the\nmodeling of the weakly conducting regions close to the electrodes. Excellent\nfits of the experimental data are achieved in this way, demonstrating the\nuniversal applicability of this approach. In the investigated ionically\nconducting materials, we find the universal appearance of a second dispersion\nregion due to electrode polarization, which is only revealed if measuring down\nto sufficiently low frequencies. This indicates the presence of a second\ncharge-transport process in ionic conductors with blocking electrodes.",
        "positive": "Viscoelastic transient of confined Red Blood Cells: The unique ability of a red blood cell to flow through extremely small\nmicrocapillaries depends on the viscoelastic properties of its membrane. Here,\nwe study in vitro the response time upon flow startup exhibited by red blood\ncells confined into microchannels. We show that the characteristic transient\ntime depends on the imposed flow strength, and that such a dependence gives\naccess to both the effective viscosity and the elastic modulus controlling the\ntemporal response of red cells. A simple theoretical analysis of our\nexperimental data, validated by numerical simulations, further allows us to\ncompute an estimate for the two-dimensional membrane viscosity of red blood\ncells, $\\eta_{mem}^{2D}\\sim 10^{-7}$ N$\\cdot$s$\\cdot$m$^{-1}$. By comparing our\nresults with those from previous studies, we discuss and clarify the origin of\nthe discrepancies found in the literature regarding the determination of\n$\\eta_{mem}^{2D}$, and reconcile seemingly conflicting conclusions from\nprevious works."
    },
    {
        "anchor": "Linear aggregation beyond isodesmic symmetry: Exactly solvable models of linear aggregation have been known since Ising's\nseminal one-dimensional model. This model is defined by a unique\nnearest-neighbour bond strength that is independent of the length of the\ncluster; known as isodesmic symmetry. Linear aggregation in real systems has\noften been associated with broken isodesmic symmetry. Here we show that\nimportant examples can be mapped to a class of one-dimensional models that are\nalso exactly solvable.",
        "positive": "Event-Chain Monte-Carlo Simulations of Dense Soft Matter Systems: We discuss the rejection-free event-chain Monte-Carlo algorithm and several\napplications to dense soft matter systems. Event-chain Monte-Carlo is an\nalternative to standard local Markov-chain Monte-Carlo schemes, which are based\non detailed balance, for example the well-known Metropolis-Hastings algorithm.\nEvent-chain Monte-Carlo is a Markov chain Monte-Carlo scheme that uses\nso-called lifting moves to achieve global balance without rejections (maximal\nglobal balance). It has been originally developed for hard sphere systems but\nis applicable to many soft matter systems and particularly suited for dense\nsoft matter systems with hard core interactions, where it gives significant\nperformance gains compared to a local Monte-Carlo simulation. The algorithm can\nbe generalized to deal with soft interactions and with three-particle\ninteractions, as they naturally arise, for example, in bead-spring models of\npolymers with bending rigidity. We present results for polymer melts, where the\nevent-chain algorithm can be used for an efficient initialization. We then move\non to large systems of semiflexible polymers that form bundles by attractive\ninteractions and can serve as model systems for actin filaments in the\ncytoskeleton. The event chain algorithm shows that these systems form networks\nof bundles which coarsen similar to a foam. Finally, we present results on\nliquid crystal systems, where the event-chain algorithm can equilibrate large\nsystems containing additional colloidal disks very efficiently, which reveals\nthe parallel chaining of disks."
    },
    {
        "anchor": "Probing interfacial effects with thermocapillary flows: We report on the thinning of supported liquid films driven by\nthermocapillarity. The liquids are oil films, of initial thicknesses of a few\ntens of microns. A local and moderate heating of the glass substrate on which\nthey are spread on induces a thermocapillary flow, which allows the formation\nof ultra-thin films. We show that, within a given time range, the thinning\ndynamics of submicron thick films is governed by the thermocapillary stress. It\nresults in a simple dependency of the thickness profiles with time, which is\nevidenced by the collapse of the data onto a master curve. The master curve\nonly depends on the liquid properties and on the thermal gradient, and allows a\nmeasurement of the latter. As the films further thin down to thicknesses within\nthe range of molecular interactions, a deviation from the master curve appears.\nAlthough all investigated oils are supposedly fully wetting glass, the nature\nof the deviation differs between alkanes and silicone oils. We attribute the\nobserved behaviors to differing signs of disjoining pressures, and this picture\nis confirmed by numerical resolution of the thin-film equation. We suggest\nthermocapillary flows can be used to finely probe molecular interactions.",
        "positive": "Designed Diamond Ground State via Optimized Isotropic Monotonic Pair\n  Potentials: We apply inverse statistical-mechanical methods to find a simple family of\noptimized isotropic, monotonic pair potentials, under certain constraints,\nwhose ground states for a wide range of pressures is the diamond crystal. These\nconstraints include desirable phonon spectra and the widest possible pressure\nrange for stability. We also ascertain the ground-state phase diagram for a\nspecific optimized potential to show that other crystal structures arise for\nother pressures. Cooling disordered configurations interacting with our\noptimized potential to absolute zero frequently leads to the desired diamond\ncrystal ground state, revealing that the capture basin for the global energy\nminimum is large and broad relative to the local energy minima basins."
    },
    {
        "anchor": "Theoretical and computational analysis of the electrophoretic polymer\n  mobility inversion induced by charge correlations: Electrophoretic (EP) mobility reversal is commonly observed for strongly\ncharged macromolecules in multivalent salt solutions. This curious effect takes\nplace, e.g., when a charged polymer, such as DNA, adsorbs excess counterions so\nthat the counterion-dressed surface charge reverses its sign, leading to the\ninversion of the polymer drift driven by an external electric field. In order\nto characterize this seemingly counterintuitive phenomenon that cannot be\ncaptured by electrostatic mean-field theories, we adapt here a previously\ndeveloped strong-coupling-dressed Poisson-Boltzmann approach to the cylindrical\ngeometry of the polyelectrolyte-salt system. Within the framework of this\nformalism, we derive an analytical polymer mobility formula dressed by charge\ncorrelations. In qualitative agreement with polymer transport experiments, this\nmobility formula predicts that the increment of the monovalent salt, the\ndecrease of the multivalent counterion valency, and the increase of the\ndielectric permittivity of the background solvent, suppress charge correlations\nand increase the multivalent bulk counterion concentration required for EP\nmobility reversal. These results are corroborated by coarse-grained molecular\ndynamics simulations showing how multivalent counterions induce mobility\ninversion at dilute concentrations and suppress the inversion effect at large\nconcentrations. This re-entrant behavior, previously observed in the\naggregation of like-charged polymer solutions, calls for verification by\npolymer transport experiments.",
        "positive": "Phase Diagrams of Multicomponent Lipid Vesicles: Effects of Spherical\n  Topology and Finite Size: We study the phase behavior of multicomponent lipid bilayer vesicles that can\nexhibit intriguing morphological patterns and lateral phase separation. We use\na modified Landau-Ginzburg model capable of describing spatially uniform\nphases, microemulsions, and modulated phases on a spherical surface. We\ncalculate its phase diagram for multiple vesicle sizes using analytical and\nnumerical techniques as well as Monte Carlo simulations. Consistent with\nprevious studies on planar systems, we find that thermal fluctuations move\nphase boundaries, stabilizing phases of higher disorder. We also show that the\nphase diagram is sensitive to the size of the system at small vesicle radii.\nSuch finite size effects are likely relevant in experiments on small,\nunilamellar vesicles and should be considered in their comparison to\ntheoretical and simulation results."
    },
    {
        "anchor": "Boundaries control active channel flows: Boundary conditions dictate how fluids, including liquid crystals, flow when\npumped through a channel. Can boundary conditions also be used to control\ninternally driven active fluids that generate flows spontaneously? By using\nnumerical simulations and stability analysis we explore how surface anchoring\nof active agents at the boundaries and substrate drag can be used to rectify\ncoherent flow of an active polar fluid in a 2D channel. Upon increasing\nactivity, a succession of dynamical states is obtained, from laminar flow to\nvortex arrays to eventual turbulence, that are controlled by the interplay\nbetween the hydrodynamic screening length and the extrapolation length\nquantifying the anchoring strength of the orientational order parameter. We\nhighlight the key role of symmetry in both flow and order and show that\ncoherent laminar flow with net throughput is only possible for weak anchoring\nand intermediate activity. Our work demonstrates the possibility of controlling\nthe nature and properties of active flows in a channel simply by patterning the\nconfining boundaries.",
        "positive": "Edwards thermodynamics of the jamming transition for frictionless\n  packings: ergodicity test and role of angoricity and compactivity: This paper illustrates how the tools of equilibrium statistical mechanics can\nhelp to explain a far-from-equilibrium problem: the jamming transition in\nfrictionless granular materials. Edwards ideas consist of proposing a\nstatistical ensemble of volume and stress fluctuations through the\nthermodynamic notion of entropy, compactivity, X, and angoricity, A (two\ntemperature-like variables). We find that Edwards thermodynamics is able to\ndescribe the jamming transition (J-point). Using the ensemble formalism we\nelucidate the following: (i)We test the combined volume-stress ensemble by\ncomparing the statistical properties of jammed configurations obtained by\ndynamics with those averaged over the ensemble of minima in the potential\nenergy landscape as a test of ergodicity. Agreement between both methods\nsupports the idea of \"thermalization\" at a given angoricity and compactivity.\n(ii) A microcanonical ensemble analysis supports the idea of maximum entropy\nprinciple for grains. (iii) The intensive variables describe the approach to\njamming through a series of scaling relations as A {\\to} 0+ and X {\\to} 0-. Due\nto the force-volume coupling, the jamming transition can be probed\nthermodynamically by a \"jamming temperature\" TJ comprised of contributions from\nA and X. (iv) The thermodynamic framework reveals the order of the jamming\nphase transition by showing the absence of critical fluctuations at jamming in\nobservables like pressure and volume. (v) Finally, we elaborate on a comparison\nwith relevant studies showing a breakdown of equiprobability of microstates."
    },
    {
        "anchor": "Kinetics of depletion interactions: Depletion interactions between colloidal particles dispersed in a fluid\nmedium are effective interactions induced by the presence of other types of\ncolloid. They are not instantaneous but build up in time. We show by means\nBrownian dynamics simulations that the fluctuations in the depletion force\nbetween two guest particles in a host dispersion of differently sized colloids\ndo not decay exponentially with time, but show a power-law dependence. A simple\nscaling theory accurately describes the dependence of the magnitude of these\nfluctuations on time, on the inter-particle distance and on the size ratio of\nguest and host particles. The consequences in particular for the dynamics of\ncolloidal mixtures are discussed.",
        "positive": "Optical Kerr effect of liquid and supercooled water: the experimental\n  and data analysis perspective: The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful\nexperimental tool enabling accurate investigations of the dynamic phenomena in\nmolecular liquids. We introduced innovative experimental and fitting\nprocedures, that permit a safe deconvolution of sample response function from\nthe instrumental function. This is a critical issue in order to measure the\ndynamics of sample presenting weak signal, e.g. liquid water. We report OKE\ndata on water measuring intermolecular vibrations and the structural relaxation\nprocesses in an extended temperature range, inclusive of the supercooled\nstates. The unpreceded data quality makes possible a solid comparison with few\ntheoretical models; the multi-mode Brownian oscillator model, the Kubo's\ndiscrete random jump model and the schematic mode-coupling model. All these\nmodels produce reasonable good fits of the OKE data of stable liquid water,\ni.e. over the freezing point. The features of water dynamics in the OKE data\nbecomes unambiguous only at lower temperatures, i.e. for water in the\nmetastable supercooled phase. Hence this data enable a valid comparison between\nthe model fits. We found that the schematic mode-coupling model provides the\nmore rigorous and complete model for water dynamics, even if is intrinsic\nhydrodynamic approach hide the molecular information."
    },
    {
        "anchor": "Review: Topology of solitons and singular defects in chiral liquid\n  crystals: Widely known for their uses in displays and electro-optics, liquid crystals\nare more than just technological marvels. They vividly reveal the topology and\nstructure of various solitonic and singular field configurations, often\nmarkedly resembling the ones arising in many field theories and in the areas\nranging from particle physics to optics, hard condensed matter and cosmology.\nIn this review, we focus on chiral nematic liquid crystals to show how these\nexperimentally highly accessible systems provide valuable insights into the\nstructure and behavior of fractional, full, and multi-integer two-dimensional\nskyrmions, dislocations and both abelian and non-abelian defect lines, as well\nas various three-dimensionally localized, often knotted structures that include\nhopfions, heliknotons, torons and twistions. We provide comparisons of some of\nthese field configurations with their topological counterparts in chiral\nmagnets, discussing close analogies between these two condensed matter systems.",
        "positive": "On the Determination of the Transition to Pure Reptation by Dielectric\n  Spectroscopy: Polymer melts show a characteristic molecular weight dependent relaxation\ntime that can be related to the unentangled and entangled regime. At high\nmolecular weights, influence of contour length fluctuations and con-straint\nrelease cease and pure reptation prevails. With the broad frequency range\ndielectric spectroscopy can fol-low polymer dynamics over a very broad\ntemperature range, with the additional advantage of recording the spec-tral\nshape which contains information on reptation. Here we investigate the apparent\ndiscrepancy in the molecular weight for the onset of pure reptation from the\nmolecular weight dependence and the spectral shape. We examined the popular\nderivative method and compared it with a version that includes higher order\nterms. Higher order terms lead to a more accurate peak shape and position than\nthose determined with the simpler version. This becomes important if\nexperimental spectra contain conductivity and polarization contributions.\nHigher order terms require the introduction of an interpolating function to\nanalyze experimental spectra, which lets the Havriliak-Negami function appear\nto be a more robust, yet reliable tool to determine the peak shapes. We reach\nthe conclusion that molecular weight dependence and spectral shape can be both\nstrongly affected by conductivity and polarization contributions. While this\nleaves uncertainties on the accurate value of the transition molecular weight,\nthe peak shape points to the existence of reptation and contour length\nfluctuations in polyisoprene with a molecular weight greater than 1000 kg/mol,\nwhich would imply a ten times greater threshold molecular weight than expected\nfrom previous estimates using the molecular weight dependence."
    },
    {
        "anchor": "When gel and glass meet: A mechanism for multistep relaxation: We use computer simulations to study the dynamics of a physical gel at high\ndensities where gelation and the glass transition interfere. We report and\nprovide detailed physical understanding of complex relaxation patterns for time\ncorrelation functions which generically decay in a three-step process. For\ncertain combinations of parameters we find logarithmic decays of the\ncorrelators and subdiffusive particle motion.",
        "positive": "Influence of Noise on Force Measurements: We demonstrate how the ineluctable presence of thermal noise alters the\nmeasurement of forces acting on microscopic and nanoscopic objects. We quantify\nthis effect exemplarily for a Brownian particle near a wall subjected to\ngravitational and electrostatic forces. Our results demonstrate that the force\nmeasurement process is prone to artifacts if the noise is not correctly taken\ninto account."
    },
    {
        "anchor": "Interfacial cooling and heating, temperature discontinuity and inversion\n  in evaporation and condensation: Although ubiquitous in nature and industrial processes, transport processes\nat the interface during evaporation and condensation are still poorly\nunderstood. Experiments have shown temperature discontinuities at the interface\nduring evaporation and condensation but the experimentally reported interface\ntemperature jump varies by two orders of magnitude. Even the direction of such\ntemperature jump is still being debated. Using kinetic-theory based expressions\nfor the interfacial mass flux and heat flux, we solve coupled problem between\nthe liquid and the vapor phase during evaporation and condensation. Our model\nshows that when evaporation or condensation happens, an intrinsic temperature\ndifference develops across the interface, due to the mismatch of the enthalpy\ncarried by vapor at the interface and the bulk region. The vapor temperature\nnear the interface cools below the saturation temperature on the liquid surface\nduring evaporation and heats up above the latter during condensation. However,\nmany existing experiments have shown an opposite trend to this prediction. We\nexplain this difference as arising from the reverse heat conduction in the\nvapor phase. Our model results compare favorably with experiments on both\nevaporation and condensation. We show that when the liquid layer is very thin,\nmost of the applied temperature difference between the solid wall and the vapor\nphase happens at the liquid-vapor interface, leading to saturation of the\nevaporation and the condensation rates and the corresponding heat transfer\nrate. This result contradicts current belief that the evaporation and\ncondensation rates are inversely proportional to the liquid film thickness.",
        "positive": "Molecular simulation analysis of structural variations in lipoplexes: We use a coarse-grained molecular model to study the self-assembly process of\ncomplexes of cationic and neutral lipids with DNA molecules (\"lipoplexes\") - a\npromising nonviral carrier of DNA for gene therapy. We identify the resulting\nstructures through direct visualization of the molecular arrangements and\nthrough calculations of the corresponding scattering plots. The latter approach\nprovides a means for comparison with published data from X-ray scattering\nexperiments. Consistent with experimental results, we find that upon increasing\nthe stiffness of the lipid material, the system tends to form lamellar\nstructures. Two characteristic distances can be extracted from the scattering\nplots of lamellar complexes - the lamellar (interlayer) spacing and the\nDNA-spacing within each layer. We find a remarkable agreement between the\ncomputed values of these two quantities and the experimental data [J. O.\nR\\\"{a}dler, I. Koltover, T. Salditt and C. R. Safinya, Science Vol. 275, 810\n(1997)] over the entire range of mole fractions of charged lipids (CLs) studied\nexperimentally. A visual inspection of the simulated systems reveals that, for\nvery high fractions of CLs, disordered structures consisting of DNA molecules\nbound to small membrane fragments are spontaneously formed. The diffraction\nplots of these non-lamellar disordered complexes appear very similar to that of\nthe lamellar structure, which makes the interpretation of the X-ray data\nambiguous. The loss of lamellar order may be the origin of the observed\nincrease in the efficiency of lipoplexes as gene delivery vectors at high\ncharge densities."
    },
    {
        "anchor": "Positron trapping and annihilation at interfaces between matrix and\n  cylindrical or spherical precipitates modeled by diffusion-reaction theory: The exact solution of a diffusion$-$reaction model for the trapping and\nannihilation of positrons at interfaces of precipitate$-$matrix composites is\npresented considering both cylindrical or spherical precipitates.\nDiffusion-limitation is taken into account for interfacial trapping from the\nsurrounding matrix as well as from the interior of the precipitate. Closed-form\nexpressions are obtained for the mean positron lifetime and for the intensity\nof the positron lifetime component associated with the interface-trapped state.\nThe model contains as special case also positron trapping at extended\nopen-volume defects like spherical voids or hollow cylinders. This makes the\nmodel applicable to all types of cylindrical- and spherical-shaped extended\ndefects irrespective of their size and their number density.",
        "positive": "Snapping of elastic strips with controlled ends: Snapping mechanisms are investigated for an elastic strip with ends imposed\nto move and rotate in time. Attacking the problem analytically via Euler's\nelastica and the second variation of the total potential energy, the number of\nstable equilibrium configurations is disclosed by varying the kinematics of the\nstrip ends. This result leads to the definition of a `universal snap surface',\ncollecting the sets of critical boundary conditions for which the system snaps.\nThe elastic energy release at snapping is also investigated, providing useful\ninsights for the optimization of impulsive motion. The theoretical predictions\nare finally validated through comparisons with experimental results and finite\nelement simulations, both fully confirming the reliability of the introduced\nuniversal surface. The presented analysis may find applications in a wide range\nof technological fields, as for instance energy harvesting and jumping robots."
    },
    {
        "anchor": "Aggregation Phenomena in Lyotropic Chromonic Liquid Crystals: We study the aggregation phenomenon in lyotropic chromonic liquid crystals as\nthe molecular concentration changes and condensing agents are added into the\nsystem. Using properties of the critical points of the Oseen-Frank energy of a\nnematic liquid crystal, combined with the geometric constraints of the\nhexagonal columnar chromonic phases, we show that the minimizers of the total\nenergy are topologically equivalent to tori, in agreement with available\nexperimental evidence on chromonic liquid crystals and DNA condensates, in\nviral capsids as well as in free solution. We model the system as bi-phasic,\nconsisting of liquid crystal molecules and water, and postulate the total\nenergy as the sum of the Flory-Huggins energy of mixing together with the\nbending and surface tension contributions of the liquid crystal. Two types of\nproblems are considered, one related to finding the optimal shape of a torus,\nonce the phase separation has occurred, and the second one that models the\nconditions leading to molecular aggregation. This work follows recent\nexperimental investigations, but without addressing the topological properties\nof the toroidal nuclei observed and focusing on how the liquid crystal order\ncompetes with the aggregation phenomenon.",
        "positive": "Force transmission and the order parameter of shear thickening: The origin of the abrupt shear thickening observed in some dense suspensions\nhas been recently argued to be a transition from frictionless (lubricated) to\nfrictional interactions between immersed particles. The Wyart-Cates rheological\nmodel, built on this scenario, introduced the concept of fraction of frictional\ncontacts $f$ as the relevant order parameter for the shear thickening\ntransition. Central to the model is the \"equation-of-state\" relating $f$ to the\napplied stress $\\sigma$, which is directly linked to the distribution of the\nnormal components of non-hydrodynamics interparticle forces. Here, we develop a\nmodel for this force distribution, based on the so-called $q$-model that we\nborrow from granular physics. This model explains the known $f(\\sigma)$ in the\nsimple case of sphere contacts displaying only sliding friction, but also\npredicts strong deviation from this \"usual\" form when stronger kinds of\nconstraints are applied on relative motion. We verify these predictions in the\ncase of contacts with rolling friction, in particular a broadening of the\nstress range over which shear thickening occurs. We finally discuss how a\nsimilar approach can be followed to predict $f(\\sigma)$ in systems with other\nvariations from the canonical system of monodisperse spheres with sliding\nfriction, in particular the case of large bidispersity."
    },
    {
        "anchor": "Gliding filament system giving both orientational order and clusters in\n  collective motion: Active matter consists of self-propelled elements exhibits fascinating\ncollective motions ranging from biological to artificial systems. Among wide\nvarieties of active matter systems, reconstituted bio-filaments moving on\nmolecular motor turf interacting purely by physical interactions provides the\nfundamental test ground for understanding biological motility. However, until\nnow, multi-filament collisions,depletion agents or binding molecules has been\nrequired for the emergence of ordered patterns in motility assay. Thus, whether\nsimple physical interactions during collisions such as steric effect without\ndepletion nor binding agents are sufficient or not for producing ordered\npatterns in motility assays remains still elusive. In this article, we\nconstructed a motility assay purely consists of kinesin motor and microtubule\nin which the frequency of binary collision can be controlled without using\ndepletion nor binding agents. By controlling strength of steric interaction and\ndensity of microtubules, we found different states; disordered state,\nlong-range orientationally ordered state, liquid-gas-like phase separated\nstate, and transitions between them. We found that a balance between cross over\nand aligning events in collisions controls transition from disorder to global\nordered state, while excessively strong steric effect leads to the phase\nseparated clusters. Furthermore, macroscopic chiral symmetry breaking observed\nas a global rotation of nematic order observed in this experiment could be\nattributed to the chirality at molecular level. Numerical simulations in which\nwe change strength of volume exclusion reproduce these experimental results.\nMoreover, it reveals the transition from long-range alignment to nematic bands\nthen to aggregations. This study may provide new insights into dynamic ordering\nby self-propelled elements through a purely physical interaction.",
        "positive": "Steric Effects in Electrolytes: A Modified Poisson-Boltzmann Equation: The adsorption of large ions from solution to a charged surface is\ninvestigated theoretically. A generalized Poisson--Boltzmann equation, which\ntakes into account the finite size of the ions is presented. We obtain\nanalytical expressions for the electrostatic potential and ion concentrations\nat the surface, leading to a modified Grahame equation. At high surface charge\ndensities the ionic concentration saturates to its maximum value. Our results\nare in agreement with recent experiments."
    },
    {
        "anchor": "Interparticle normal force in highly porous granular matter during\n  compression: We perform a numerical simulation of compression of a highly porous dust\naggregate of monodisperse spheres. We find that the average interparticle\nnormal force within the aggregate is inversely proportional to both the filling\nfactor and the average coordination number, and we also derive this relation\ntheoretically. Our findings would be applicable for granular matter of\narbitrary structures, as long as the constituent particles are monodisperse\nspheres.",
        "positive": "Molecular reorientation in hydrogen-bonding liquids: through algebraic\n  $\\sim t^{-3/2}$ relaxation toward exponential decay: We present a model for the description of orientational relaxation in\nhydrogen-bonding liquids. The model contains two relaxation parameters which\nregulate the intensity and efficiency of dissipation, as well as the memory\nfunction which is responsible for the short-time relaxation effects. It is\nshown that the librational portion of the orientational relaxation is described\nby an algebraic $\\sim t^{-3/2}$ contribution, on top of which more rapid and\nnon-monotonous decays caused by the memory effects are superimposed. The\nlong-time behavior of the orientational relaxation is exponential, although\nnon-diffusional. It is governed by the rotational energy relaxation. We apply\nthe model to interpret recent molecular dynamic simulations and polarization\npump-probe experiments on $HOD$ in liquid $D_{2}O$ [C. J. Fecko et al, J. Chem.\nPhys. 122, 054506 (2005)]."
    },
    {
        "anchor": "Viscoelastic fractures in stratified composite materials: \"lenticular\n  trumpet\": We consider fractures in a stratified composite material with solid layers\nseparated by thin slices of extremely soft matter. Viscoelastic effects\nassociated with the soft layers are taken into account via the simplest model\nfor weakly cross-linked polymers. We find that certain small cracks running\nalong layers take a new \"trumpet\" shape quite different from previously known\nshapes.",
        "positive": "Cargo Towing by Artificial Swimmers: An active swimmer can tow a passive cargo by binding it to form a\nself-propelling dimer. The orientation of the cargo relative to the axis of the\nactive dimer's head is determined by the hydrodynamic interactions associated\nwith the propulsion mechanism of the latter. We show how the tower-cargo\nangular configuration greatly influences the dimer's diffusivity and,\ntherefore, the efficiency of the active swimmer as a micro-towing motor."
    },
    {
        "anchor": "Stretching An Anisotropic DNA: We present a perturbation theory to find the response of an anisotropic DNA\nto the external tension. It is shown that the anisotropy has a nonzero but\nsmall contribution to the force-extension curve of the DNA. Thus an anisotropic\nDNA behaves like an isotropic one with an effective bending constant equal to\nthe harmonic average of its soft and hard bending constants.",
        "positive": "Aging of rotational diffusion in colloidal gels and glasses: We study the rotational diffusion of aging Laponite suspensions for a wide\nrange of concentrations using depolarized dynamic light scattering. The\nmeasured orientational correlation functions undergo an ergodic to non-ergodic\ntransition that is characterized by a concentration-dependent\nergodicity-breaking time. We find that the relaxation times associated with\nrotational degree of freedom as a function of waiting time, when scaled with\ntheir ergodicity-breaking time, collapse on two distinct master curves. These\nmaster curves are similar to those previously found for the translational\ndynamics; The two different classes of behavior were attributed to colloidal\ngels and glasses. Therefore, the aging dynamics of rotational degree of freedom\nprovides another signature of the distinct dynamical behavior of colloidal gels\nand glasses."
    },
    {
        "anchor": "Influence of long-range correlated surface and near the surface disorder\n  on the process of adsorption of long-flexible polymer chains: The influence of long-range correlated surface and decaying near surface\ndisorder with quenched defects is studied. We consider a correlation function\nfor the defects of the form $\\frac{e^{-z/\\xi}}{r^{a}}$, where $a<d-1$ and $z$\nbeing the coordinate in the direction perpendicular to the surface and $r$\ndenotes the distance parallel to the surface. We investigate the process of\nadsorption of long-flexible polymer chains with excluded volume interactions on\na \"marginal\" and attractive wall in the framework of renormalization group\nfield theoretical approach up to first order of perturbation theory in a double\n($\\epsilon$,$\\delta$)- expansion ($\\epsilon=4-d$, $\\delta=3-a$) for the\nsemi-infinite $|\\phi|^4$ $O(m,n)$ model with the above mentioned type of\nsurface and near the surface disorder in the limit $m,n\\to 0$. In particular we\nstudy two limiting cases. First, we investigate the scenario where the chain's\nextension it much larger then $\\xi$. Second, we consider the case where the\nchain's extension is of the order of $\\xi$. For both cases we obtained series\nfor bulk and the whole set of surface critical exponents, characterizing the\nprocess of adsorption of long-flexible polymer chains at the surface. The\npolymer linear dimensions parallel and perpendicular to the surface and the\ncorresponding partition functions as well as the behavior of monomer density\nprofiles and the fraction of adsorbed monomers at the surface and in the volume\nare studied.",
        "positive": "Macroscopic yielding in jammed solids is accompanied by a\n  non-equilibrium first-order transition in particle trajectories: We use computer simulations to analyse the yielding transition during\nlarge-amplitude oscillatory shear of a simple model for soft jammed solids.\nSimultaneous analysis of global mechanical response and particle-scale motion\ndemonstrates that macroscopic yielding, revealed by a smooth crossover in\nmechanical properties, is accompanied by a sudden change in the particle\ndynamics, which evolves from non-diffusive motion to irreversible diffusion as\nthe amplitude of the shear is increased. We provide numerical evidence that\nthis sharp change corresponds to a non-equilibrium first-order dynamic phase\ntransition, thus establishing the existence of a well-defined microscopic\ndynamic signature of the yielding transition in amorphous materials in\noscillatory shear."
    },
    {
        "anchor": "Interfacial activity dynamics of confined active droplets: Active emulsions can spontaneously form self-propelled droplets or phoretic\nmicropumps. It has been predicted that the interaction with their\nself-generated chemical fields can lead to multistable higher-order flows and\nchemodynamic phenomena. However, it remains unclear how such\nreaction-advection-diffusion instabilities can emerge from the interplay\nbetween chemical reactions and interfacial hydrodynamics. Here, we\nsimultaneously measure the flow fields and the chemical concentration fields\nusing dual-channel microscopy for oil droplets that dynamically solubilize in a\nsupramicellar aqueous surfactant solution. We developed an experimentally\ntractable setup with micropumps, droplets that are pinned between the top and\nbottom surfaces of a microfluidic reservoir, which we compare directly to\npredictions from a Brinkman squirmer model to account for the confinement. With\nincreasing droplet radius, we observe (i) a migration of vortex flows from the\nposterior to the anterior of the droplet, analogous to a transition from\npusher- to puller-type swimmers, (ii) a bistability between dipolar and\nquadrupolar flow modes, and, eventually, (iii) a transition to multipolar\nmodes. We also investigate how the dynamics evolve over long time periods.\nTogether, our observations suggest that a local build-up of chemical products\nleads to a saturation of the surface, which controls the propulsion mechanism.\nThese multistable dynamics can be explained by the competing time scales of\nslow micellar diffusion governing the chemical buildup and faster molecular\ndiffusion powering the underlying transport mechanism. Our results are directly\nrelevant to phoretic micropumps, but also shed light on the interfacial\nactivity dynamics of self-propelled droplets and other active emulsion systems",
        "positive": "The vanishing limit of the square-well fluid: the adhesive hard sphere\n  model as a reference system: We report a simulation study of the gas-liquid critical point for the\nsquare-well potential, for values of well width delta as small as 0.005 times\nthe particle diameter sigma. For small delta, the reduced second virial\ncoefficient at the critical point B_2*c is found to depend linearly on delta.\nThe observed weak linear dependence is not sufficient to produce any\nsignificant observable effect if the critical temperature T_c is estimated via\na constant B_2*c assumption, due to the highly non linear transformation\nbetween B_2*c and T_c. This explains the previously observed validity of the\nlaw of corresponding states. The critical density rho_c is also found to be\nconstant when measured in units of the cubed average distance between two\nbonded particles (1+0.5 delta)/sigma. The possibility of describing the delta\n-> 0 dependence with precise functional forms provides improved acccurate\nestimates of the critical parameters of the adhesive hard-sphere AHS model."
    },
    {
        "anchor": "Nucleation theory of polymer crystallization with conformation entropy: Based on classical nucleation theory, we propose a couple of theoretical\nmodels for the nucleation of polymer crystallization, i.e. one for a single\nchain system (Model S) and the other for a multi-chain system (Model M). In\nthese models, we assume that the nucleus is composed of tails, loops and a\ncylindrical ordered region, and we evaluate the conformation entropy explicitly\nby introducing a transfer matrix. Using these two models, we evaluate the\noccurrence probability of critical nucleus as a function of the polymer chain\nstiffness. We found that the critical nucleus in Model M is easier to occur\nthan in Model S because, for semi-flexible chains, the nucleus in Model M can\ngrow by adding a new polymer chain into the nucleus rather than to diminish the\nloop and tail parts as in the case of Model S.",
        "positive": "Implicit and explicit solvent models for the simulation of a single\n  polymer chain in solution: Lattice Boltzmann vs Brownian dynamics: We present a comparative study of two computer simulation methods to obtain\nstatic and dynamic properties of dilute polymer solutions. The first approach\nis a recently established hybrid algorithm based upon dissipative coupling\nbetween Molecular Dynamics and lattice Boltzmann (LB), while the second is\nstandard Brownian Dynamics (BD) with fluctuating hydrodynamic interactions.\nApplying these methods to the same physical system (a single polymer chain in a\ngood solvent in thermal equilibrium) allows us to draw a detailed and\nquantitative comparison in terms of both accuracy and efficiency. It is found\nthat the static conformations of the LB model are distorted when the box length\nL is too small compared to the chain size. Furthermore, some dynamic properties\nof the LB model are subject to an $L^{-1}$ finite size effect, while the BD\nmodel directly reproduces the asymptotic $L \\to \\infty$ behavior. Apart from\nthese finite size effects, it is also found that in order to obtain the correct\ndynamic properties for the LB simulations, it is crucial to properly thermalize\nall the kinetic modes. Only in this case, the results are in excellent\nagreement with each other, as expected. Moreover, Brownian Dynamics is found to\nbe much more efficient than lattice Boltzmann as long as the degree of\npolymerization is not excessively large."
    },
    {
        "anchor": "Density functional for hard hyperspheres from a tensorial-diagrammatic\n  series: We represent the free energy functional by a diagrammatic series with\ntensorial coefficients indexed by powers of length scale. For hard cores, we\nobtain Percus' exact functional in one dimension and the Kierlik-Rosinberg form\nof fundamental measures theory in three dimensions. In five dimensions, the\nfunctional describes bulk fluids better than Percus-Yevick theory does. At\nplanar walls density profiles oscillate with smaller periods than in lower\ndimensions. Our findings open up avenues for treating both more general\nhigh-dimensional systems, as well as three-dimensional mixtures via dimensional\nreduction.",
        "positive": "Experimental study of the jamming transition at zero temperature: We experimentally investigate jamming in a quasi-two-dimensional granular\nsystem of automatically swelling particles and show that a maximum in the\nheight of the first peak of the pair correlation function is a structural\nsignature of the jamming transition at zero temperature. The same signature is\nalso found in the second peak of the pair correlation function, but not in the\nthird peak, reflecting the underlying singularity of jamming transition. We\nalso study the development of clusters in this system. A static length scale\nextracted from the cluster structure reaches the size of the system when the\nsystem approaches the jamming point. Finally, we show that in a highly\ninhomogeneous system, friction causes the system to jam in series of steps. In\nthis case, jamming may be obtained through successive buckling of force chains."
    },
    {
        "anchor": "DC electrokinetics for spherical particles in salt-free concentrated\n  suspensions including ion size effects: We study the electrophoretic mobility of spherical particles and the\nelectrical conductivity in salt-free concentrated suspensions including finite\nion size effects. An ideal salt-free suspension is composed of just charged\ncolloidal particles and the added counterions that counterbalance their surface\ncharge. In a very recent paper [Roa et al., Phys. Chem. Chem. Phys., 2011, 13,\n3960- 3968] we presented a model for the equilibrium electric double layer for\nthis kind of suspensions considering the size of the counterions, and now we\nextend this work to analyze the response of the suspension under a static\nexternal electric field. The numerical results show the high importance of such\ncorrections for moderate to high particle charges, especially when a region of\nclosest approach of the counterions to the particle surface is considered. The\npresent work sets the basis for further theoretical models with finite ion size\ncorrections, concerning particularly the ac electrokinetics and rheology of\nsuch systems.",
        "positive": "Water-like anomalies as a function of tetrahedrality: Tetrahedral interactions describe the behaviour of the most abundant and\ntechnologically important materials on Earth, such as water, silicon, carbon,\ngermanium, and countless others. Despite their differences, these materials\nshare unique common physical behaviours, such as liquid anomalies, open\ncrystalline structures, and extremely poor glass-forming ability at ambient\npressure. To reveal the physical origin of these anomalies and their link to\nthe shape of the phase diagram, we systematically study the properties of the\nStillinger-Weber potential as a function of the strength of the tetrahedral\ninteraction $\\lambda$. We uncover a new transition to a re-entrant spinodal\nline at low values of $\\lambda$, accompanied with a change in the dynamical\nbehaviour, from Non-Arrhenius to Arrhenius. We then show that a two-state model\ncan provide a comprehensive understanding on how the thermodynamic and dynamic\nanomalies of this important class of materials depend on the strength of the\ntetrahedral interaction. Our work establishes a deep link between the shape of\nphase diagram and the thermodynamic and dynamic properties through local\nstructural ordering in liquids, and hints at why water is so special among all\nsubstances."
    },
    {
        "anchor": "Recent advances in blood rheology: A review: Due to the potential impact on the diagnosis and treatment of various\ncardiovascular diseases, work on the rheology of blood has significantly\nexpanded in the last decade, both experimentally and theoretically.\nExperimentally, blood has been confirmed to demonstrate a variety of\nnon-Newtonian rheological characteristics, including pseudoplasticity,\nviscoelasticity, and thixotropy. New rheological experiments and the\ndevelopment of more controlled experimental protocols on more extensive,\nbroadly physiologically characterized, human blood samples demonstrate the\nsensitivity of aspects of hemorheology to several physiological factors. For\nexample, at high shear rates to the red blood cells elastically deformation,\nimparting viscoelasticity, while and at low shear rates, they form rouleaux\nstructures that impart additional, thixotropic behavior. In addition to these\nadvances in experimental methods and validated data sets, significant advances\nhave also been made in both microscopic simulations and macroscopic, continuum,\nmodeling, as well as novel, multiscale approaches. We outline and evaluate the\nmost promising of these recent advances. Although we primarily focus on human\nblood rheology, we also discuss recent observations on variations across some\nanimal species that provide some indication on evolutionary effects.",
        "positive": "Actuation of thin nematic elastomer sheets with controlled heterogeneity: Nematic elastomers and glasses deform spontaneously when subjected to\ntemperature changes. This property can be exploited in the design of\nheterogeneously patterned thin sheets that deform into a non-trivial shape when\nheated or cooled. In this paper, we start from a variational formulation for\nthe entropic elastic energy of liquid crystal elastomers and we derive an\neffective two-dimensional metric constraint, which links the deformation and\nthe heterogeneous director field. Our main results show that satisfying the\nmetric constraint is both necessary and sufficient for the deformation to be an\napproximate minimizer of the energy. We include several examples which show\nthat the class of deformations satisfying the metric constraint is quite rich."
    },
    {
        "anchor": "Brownian Dynamics Simulation of Polydisperse Hard Spheres: Standard algorithms for the numerical integration of the Langevin equation\nrequire that interactions are slowly varying during to the integration\ntimestep. This in not the case for hard-body systems, where there is no\nclearcut between the correlation time of the noise and the timescale of the\ninteractions. Starting from a short time approximation of the Smoluchowsky\nequation, we introduce an algorithm for the simulation of the overdamped\nBrownian dynamics of polydisperse hard-spheres in absence of hydrodynamics\ninteractions and briefly discuss the extension to the case of external drifts.",
        "positive": "Magnetization and susceptibility of ferrofluids: A second-order Taylor series expansion of the free energy functional provides\nanalytical expressions for the magnetic field dependence of the free energy and\nof the magnetization of ferrofluids, here modelled by dipolar Yukawa\ninteraction potentials. The corresponding hard core dipolar Yukawa reference\nfluid is studied within the framework of the mean spherical approximation. Our\nfindings for the magnetic and phase equilibrium properties are in quantitative\nagreement with previously published and new Monte Carlo simulation data."
    },
    {
        "anchor": "A robotic crawler exploiting directional frictional interactions:\n  experiments, numerics, and derivation of a reduced model: We present experimental and numerical results for a model crawler which is\nable to extract net positional changes from reciprocal shape changes, i.e.\n'breathing-like' deformations, thanks to directional, frictional interactions\nwith a textured solid substrate, mediated by flexible inclined feet. We also\npresent a simple reduced model that captures the essential features of the\nkinematics and energetics of the gait, and compare its predictions with the\nresults from experiments and from numerical simulations.",
        "positive": "Potential of mean force between like-charged nanoparticles: Many-body\n  effect: Ion-mediated interaction is important for the properties of polyelectrolytes\nsuch as colloids and nucleic acids. The effective pair interactions between two\npolyelectrolytes have been investigated extensively, but the many-body effect\nfor multiple polyelectrolytes still remains elusive. In this work, the\nmany-body effect in potential of mean force (PMF) between like-charged\nnanoparticles in various salt solutions has been comprehensively examined by\nMonte Carlo simulation and the nonlinear Poisson-Boltzmann theory. Our\ncalculations show that, at high 1:1 salt, the PMF is weakly repulsive and\nappears additive, while at low 1:1 salt, the additive assumption overestimates\nthe repulsive many-body PMF. At low 2:2 salt, the pair PMF appears weakly\nrepulsive while the many-body PMF can become attractive. In contrast, at high\n2:2 salt, the pair PMF is apparently attractive while the many-body effect can\ncause a weaker attractive PMF than that from the additive assumption. Our\nmicroscopic analyses suggest that the elusive many-body effect is attributed to\nion-binding which is sensitive to ion concentration, ion valence, number of\nnanoparticles and charges on nanoparticles."
    },
    {
        "anchor": "On the First Passage Time and Leapover Properties of Levy Motions: We investigate two coupled properties of Levy stable random motions: The\nfirst passage times (FPTs) and the first passage leapovers (FPLs). While, in\ngeneral, the FPT problem has been studied quite extensively, the FPL problem\nhas hardly attracted any attention. Considering a particle that starts at the\norigin and performs random jumps with independent increments chosen from a Levy\nstable probability law $\\lambda_(alpha,beta)(x)$, the FPT measures how long it\ntakes the particle to arrive at or cross a target. The FPL addresses a\ndifferent question: Given that the first passage jump crosses the target, then\nhow far does it get beyond the target? These two properties are investigated\nfor three subclasses of Levy stable motions: (i) symmetric Levy motions\ncharacterized by Levy index $\\alpha$ ($0<\\alpha<2$) and skewness parameter\n$\\beta=0$, (ii) one-sided Levy motions with $0<\\alpha<1$, $\\beta=1$, and (iii)\ntwo-sided skewed Levy motions, the extreme case, $1<\\alpha<2$, $\\beta=-1$.",
        "positive": "Generalized Flory Theory for Rotational Symmetry Breaking of Complex\n  Macromolecules: We report on spontaneous rotational symmetry breaking in a minimal model of\ncomplex macromolecules with branches and cycles. The transition takes place as\nthe strength of the self-repulsion is increased. At the transition point, the\ndensity distribution transforms from isotropic to anisotropic. We analyze this\ntransition using a variational mean-field theory that combines the\nGibbs-Bogolyubov-Feynman inequality with the concept of the Laplacian matrix.\nThe density distribution of the broken symmetry state is shown to be determined\nby the eigenvalues and eigenvectors of this Laplacian matrix. Physically, this\nreflects the increasing role of the underlying topological structure in\ndetermining the density of the macromolecule when repulsive interactions\ngenerate internal tension Eventually, the variational free energy landscape\ndevelops a complex structure with multiple competing minima."
    },
    {
        "anchor": "Contribution of dipolar bridging to phospholipid membrane interactions:\n  a mean-field analysis: We develop a model of interacting zwitterionic membranes with rotating\nsurface dipoles immersed in a monovalent salt, and implement it in a field\ntheoretic formalism. In the mean-field regime of monovalent salt, the\nelectrostatic forces between the membranes are characterized by a non-uniform\ntrend: at large membrane separations, the interfacial dipoles on the opposing\nsides behave as like-charge cations and give rise to repulsive membrane\ninteractions; at short membrane separations, the anionic field induced by the\ndipolar phosphate groups sets the behavior in the intermembrane region. The\nattraction of the cationic nitrogens in the dipolar lipid headgroups leads to\nthe adhesion of the membrane surfaces via dipolar bridging. The underlying\ncompetition between the opposing field components of the individual dipolar\ncharges leads to the non-uniform salt ion affinity of the zwitterionic membrane\nwith respect to the separation distance; large inter-membrane separations imply\nanionic excess while small, nanometer size separations, favor cationic excess.\nThis complex ionic selectivity of zwitterionic membranes may have relevant\nrepercussions on nanofiltration and nanofluidic transport techniques.",
        "positive": "Phonon dispersions of cluster crystals: We analyze the ground states and the elementary collective excitations\n(phonons) of a class of systems, which form cluster crystals in the absence of\nattractions. Whereas the regime of moderate-to-high-temperatures in the phase\ndiagram has been analyzed in detail by means of density functional\nconsiderations (Likos C N, Mladek B M, Gottwald D and Kahl G 2007 {\\it\nJ.~Chem.~Phys.}\\ {\\bf 126} 224502), the present approach focuses on the\ncomplementary regime of low temperatures. We establish the existence of an\ninfinite cascade of isostructural transitions between crystals with different\nlattice site occupancy at $T=0$ and we quantitatively demonstrate that the\nthermodynamic instabilities are bracketed by mechanical instabilities arising\nfrom long-wavelength acoustical phonons. We further show that all optical modes\nare degenerate and flat, giving rise to perfect realizations of Einstein\ncrystals. We calculate analytically the complete phonon spectrum for the whole\nclass of models as well as the Helmholtz free energy of the systems. On the\nbasis of the latter, we demonstrate that the aforementioned isostructural phase\ntransitions must terminate at an infinity of critical points at low\ntemperatures, brought about by the anharmonic contributions in the Hamiltonian\nand the hopping events in the crystals."
    },
    {
        "anchor": "How to derive a predictive active field theory: a step-by-step tutorial: The study of active soft matter has developed into one of the most rapidly\ngrowing areas of physics. Field theories, which can be developed either via\nphenomenological considerations or by coarse-graining of a microscopic model,\nare a very useful tool for understanding active systems. Here, we provide a\ndetailed review of a particular coarse-graining procedure, the\ninteraction-expansion method (IEM). The IEM allows for the systematic\nmicroscopic derivation of predictive field theories for systems of interacting\nactive particles. We explain in detail how it can be used for a microscopic\nderivation of active model B+, which is a widely used scalar active matter\nmodel. Extensions and possible future applications are also discussed.",
        "positive": "Polymer patterning by laser-induced multi-point initiation of frontal\n  polymerization: Frontal polymerization (FP) is an approach for thermosetting plastics at\nlower energy cost than an autoclave. The potential to generate simultaneous\npropagation of multiple polymerization fronts has been discussed as an exciting\npossibility. However, FP initiated at more than two points simultaneously has\nnot been demonstrated. Multi-point initiation could enable both large scale\nmaterial fabrication and unique pattern generation. Here the authors present\nlaser-patterned photothermal heating as a method for simultaneous initiation of\nFP at multiple locations in a 2-D sample. Carbon black particles are mixed into\nliquid resin (dicyclopentadiene) to enhance absorption of light from a\nTi:Sapphire laser (800 nm) focused on a sample. The laser is time-shared by\nrapid steering among initiation points, generating polymerization using up to\nseven simultaneous points of initiation. This process results in the formation\nof both symmetric and asymmetric seam patterns resulting from the collision of\nfronts. The authors also present and validate a theoretical framework for\npredicting the seam patterns formed by front collisions. This framework allows\nthe design of novel patterns via an inverse solution for determining the\ninitiation points required to form a desired pattern. Future applications of\nthis approach could enable rapid, energy-efficient manufacturing of novel\ncomposite-like patterned materials."
    },
    {
        "anchor": "Reaction Kinetics in Polymer Melts: We study the reaction kinetics of end-functionalized polymer chains dispersed\nin an unreactive polymer melt. Starting from an infinite hierarchy of coupled\nequations for many-chain correlation functions, a closed equation is derived\nfor the 2nd order rate constant $k$ after postulating simple physical bounds.\nOur results generalize previous 2-chain treatments (valid in dilute reactants\nlimit) by Doi, de Gennes, and Friedman and O'Shaughnessy, to arbitrary initial\nreactive group density $n_0$ and local chemical reactivity $Q$. Simple mean\nfield (MF) kinetics apply at short times, $k \\sim Q$. For high $Q$, a\ntransition occurs to diffusion-controlled (DC) kinetics with $k \\approx\nx_t^3/t$ (where $x_t$ is rms monomer displacement in time $t$) leading to a\ndensity decay $n_t \\approx n_0 - n_0^2 x_t^3$. If $n_0$ exceeds the chain\noverlap threshold, this behavior is followed by a regime where $n_t \\approx\n1/x_t^3$ during which $k$ has the same power law dependence in time, $k \\approx\nx_t^3/t$, but possibly different numerical coefficient. For unentangled melts\nthis gives $n_t \\sim t^{-3/4}$ while for entangled cases one or more of the\nsuccessive regimes $n_t \\sim t^{-3/4}$, $t^{-3/8}$ and $t^{-3/4}$ may be\nrealized depending on the magnitudes of $Q$ and $n_0$. Kinetics at times longer\nthan the longest polymer relaxation time $\\tau$ are always MF. If a DC regime\nhas developed before $\\tau$ then the long time rate constant is $k \\approx\nR^3/\\tau$ where $R$ is the coil radius. We propose measuring the above kinetics\nin a model experiment where radical end groups are generated by photolysis.",
        "positive": "Pre-dewetting transition on a hydrophobic wall: Statics and dynamics: For one-component fluids, we predict a pre-dewetting phase transition between\na thin and thick low-density layer in liquid on a wall repelling the fluid.\nThis is the case of a hydrophobic wall for water. A pre-dewetting line starts\nfrom the coexistence curve and ends at a surface critical point in the phase\ndiagram. We calculate this line numerically using the van der Waals model and\nanalytically using the free energy expansion up to the quartic order. We also\nexamine the pre-dewetting dynamics of a layer created on a hydrophobic spot on\na heterogeneous wall. It is from a thin to thick layer during decompression and\nfrom a thick to thin layer during compression. Upon the transition, a liquid\nregion above the film is cooled for decompression and heated for compression\ndue to latent heat convection and a small pressure pulse is emitted from the\nfilm into the liquid."
    },
    {
        "anchor": "Designing minimally-segregating granular mixtures for gravity-driven\n  surface flows: In dense flowing bidisperse particle mixtures varying in size or density\nalone, smaller particles sink (driven by percolation) and lighter particles\nrise (driven by buoyancy). But when the particle species differ from each other\nin both size and density, percolation and buoyancy can either enhance\n(large/light and small/heavy) or oppose (large/heavy and small/light) each\nother. In the latter case, a local equilibrium condition can exist in which the\ntwo segregation mechanisms balance and particles remain mixed: this allows the\ndesign of minimally-segregating mixtures by specifying particle size ratio,\ndensity ratio, and mixture concentration. Using experimentally validated DEM\nsimulations, we show that mixtures specified by the methodology remain\nrelatively well-mixed in the thin rapid surface flows characteristic of heaps\nand tumblers commonly used in industry. Furthermore, minimally-segregating\nparticle mixtures prepared in a fully segregated state in a tumbler mix over\ntime and eventually reach a state of nearly uniform species concentration.",
        "positive": "Force density functional theory in- and out-of-equilibrium: When a fluid is subject to an external field, as is the case near an\ninterface or under spatial confinement, then the density becomes spatially\ninhomogeneous. Although the one-body density provides much useful information,\na higher level of resolution is provided by the two-body correlations. These\ngive a statistical description of the internal microstructure of the fluid and\nenable calculation of the average interparticle force, which plays an essential\nrole in determining both the equilibrium and dynamic properties of interacting\nfluids. We present a theoretical framework for the description of inhomogeneous\n(classical) many-body systems, based explicitly on the two-body correlation\nfunctions. By consideration of local Noether-invariance against spatial\ndistortion of the system we demonstrate the fundamental status of the\nYvon-Born-Green (YBG) equation as a local force-balance within the fluid. Using\nthe inhomogeneous Ornstein-Zernike equation we show that the two-body\ncorrelations are density functionals and, thus, that the average interparticle\nforce entering the YBG equation is also a functional of the one-body density.\nThe force-based theory we develop provides an alternative to standard density\nfunctional theory for the study of inhomogeneous systems both in- and\nout-of-equilibrium. We compare force-based density profiles to the results of\nthe standard potential-based (dynamical) density functional theory. In\nequilibrium, we confirm both analytically and numerically that the standard\napproach yields profiles that are consistent with the compressibility pressure,\nwhereas the force-density functional gives profiles consistent with the virial\npressure. The structure of the theory offers deep insights into the nature of\ncorrelation in dense and inhomogeneous systems."
    },
    {
        "anchor": "Group projector generalization of dirac-heisenberg model: The general form of the operators commuting with the ground representation\n(appearing in many physical problems within single particle approximation) of\nthe group is found. With help of the modified group projector technique, this\nresult is applied to the system of identical particles with spin independent\ninteraction, to derive the Dirac-Heisenberg hamiltonian and its effective space\nfor arbitrary orbital occupation numbers and arbitrary spin. This gives\ntransparent insight into the physical contents of this hamiltonian, showing\nthat formal generalizations with spin greater than 1/2 involve nontrivial\nadditional physical assumptions.",
        "positive": "Flow, Ordering and Jamming of Sheared Granular Suspensions: We study the rheological properties of a granular suspension subject to\nconstant shear stress by constant volume molecular dynamics simulations. We\nderive the system `flow diagram' in the volume fraction/stress plane\n$(\\phi,F)$: at low $\\phi$ the flow is disordered, with the viscosity obeying a\nBagnold-like scaling only at small $F$ and diverging as the jamming point is\napproached; if the shear stress is strong enough, at higher $\\phi$ an ordered\nflow regime is found, the order/disorder transition being marked by a sharp\ndrop of the viscosity. A broad jamming region is also observed where, in\nanalogy with the glassy region of thermal systems, slow dynamics followed by\nkinetic arrest occurs when the ordering transition is prevented."
    },
    {
        "anchor": "Formation and growth of clusters in colloidal suspensions: Depending on the pH value and salt concentration of Al2O3 suspensions\ndifferent microstructures can form. Especially the clustered one is of major\ninterest for industrial purposes as found in the production of ceramics. In\nthis paper we investigate the clustered microstructure by means of a coupled\nStochastic Rotation Dynamics (SRD) and Molecular Dynamics (MD) simulation. In\norder to gain statistics within a system containing numerous clusters, large\nsimulation volumes are needed. We present our parallel implementation of the\nsimulation algorithm as well as a newly developed cluster detection and\ntracking algorithm. We then show first results of measured growth rates and\ncluster size distributions to validate the applicability of our method.",
        "positive": "Forced Granular Orifice Flow: The flow of granular material through an orifice is studied experimentally as\na function of force $F$ pushing the flow. It is found that the flow rate\nincreases linearly with $F$ -- a new, unexpected result that is in contrast to\nthe usual view that $F$, completely screened by an arch formed around the\norifice, has no way of altering the rate. Employing energy balance, we show\nthat this behavior results mainly from dissipation in the granular material."
    },
    {
        "anchor": "Collisional Model for Granular Impact Dynamics: When an intruder strikes a granular material from above, the grains exert a\nstopping force which decelerates and stops the intruder. Many previous studies\nhave used a macroscopic force law, including a drag force which is quadratic in\nvelocity, to characterize the decelerating force on the intruder. However, the\nmicroscopic origins of the force law terms are still a subject of debate. Here,\ndrawing from previous experiments with photoelastic particles, we present a\nmodel which describes the velocity-squared force in terms of repeated\ncollisions with clusters of grains. From our high speed photoelastic data, we\ninfer that `clusters' correspond to segments of the strong force network that\nare excited by the advancing intruder. The model predicts a scaling relation\nfor the velocity-squared drag force that accounts for the intruder shape.\nAdditionally, we show that the collisional model predicts an instability to\nrotations, which depends on the intruder shape. To test this model, we perform\na comprehensive experimental study of the dynamics of two-dimensional granular\nimpacts on beds of photoelastic disks, with different profiles for the leading\nedge of the intruder. We particularly focus on a simple and useful case for\ntesting shape effects by using triangular-nosed intruders. We show that the\ncollisional model effectively captures the dynamics of intruder deceleration\nand rotation; i.e., these two dynamical effects can be described as two\ndifferent manifestations of the same grain-scale physical processes.",
        "positive": "Glassy dynamics in asymmetric binary mixtures of hard-spheres: The binary hard-sphere mixture is one of the simplest representations of a\nmany-body system with competing time and length scales. This model is relevant\nto fundamentally understand both the structural and dynamical properties of\nmaterials, such as metallic melts, colloids, polymers and bio-based composites.\nIt also allows us to study how different scales influence the physical behavior\nof a multicomponent glass-forming liquid; a question that still awaits a\nunified description. In this contribution, we report on distinct dynamical\narrest transitions in highly asymmetric binary colloidal mixtures, namely, a\nsingle glass of big particles, in which the small species remains ergodic, and\na double glass with the simultaneous arrest of both components. When the\nmixture approaches any glass transition, the relaxation of the collective\ndynamics of both species becomes coupled. In the single glass domain, spatial\nmodulations occur due to the structure of the large spheres, a feature not\nobserved in the two-glass domain. The relaxation of the \\emph{self} dynamics of\nsmall and large particles, in contrast, become decoupled at the boundaries of\nboth transitions; the large species always displays dynamical arrest, whereas\nthe small ones appear arrested only in the double glass. Thus, in order to\nobtain a complete picture of the distinct glassy states, one needs to take into\naccount the dynamics of both species."
    },
    {
        "anchor": "Threading the Needle: Generating Textures in Nematics: The Hopf fibration is an example of a texture: a topologically stable,\nsmooth, global configuration of a field. Here we demonstrate the controlled\nsculpting of the Hopf fibration in nematic liquid crystals through the control\nof point defects. We demonstrate how these are related to torons by use of a\ntopological visualization technique derived from the Pontryagin-Thom\nconstruction.",
        "positive": "Erosion of a granular bed driven by laminar fluid flow: Motivated by examples of erosive incision of channels in sand, we investigate\nthe motion of individual grains in a granular bed driven by a laminar fluid to\ngive us new insights into the relationship between hydrodynamic stress and\nsurface granular flow. A closed cell of rectangular cross-section is partially\nfilled with glass beads and a constant fluid flux $Q$ flows through the cell.\nThe refractive indices of the fluid and the glass beads are matched and the\ncell is illuminated with a laser sheet, allowing us to image individual beads.\nThe bed erodes to a rest height $h_r$ which depends on $Q$. The Shields\nthreshold criterion assumes that the non-dimensional ratio $\\theta$ of the\nviscous stress on the bed to the hydrostatic pressure difference across a grain\nis sufficient to predict the granular flux. Furthermore, the Shields criterion\nstates that the granular flux is non-zero only for $\\theta >\\theta_c$. We find\nthat the Shields criterion describes the observed relationship $h_r \\propto\nQ^{1/2}$ when the bed height is offset by approximately half a grain diameter.\nIntroducing this offset in the estimation of $\\theta$ yields a collapse of the\nmeasured Einstein number $q^*$ to a power-law function of $\\theta - \\theta_c$\nwith exponent $1.75 \\pm 0.25$. The dynamics of the bed height relaxation are\nwell described by the power law relationship between the granular flux and the\nbed stress."
    },
    {
        "anchor": "Microstructure-Stabilized Blue Phase Liquid Crystals: We show that micron-scale two-dimensional (2D) honeycomb microwells can\nsignificantly improve the stability of blue phase liquid crystals (BPLCs).\nPolymeric microwells made by direct laser writing improve various features of\nthe blue phase (BP) including a dramatic extension of stable temperature range\nand a large increase both in reflectivity and thermal stability of the\nreflective peak wavelength. These results are mainly attributed to the\nomni-directional anchoring of the isotropically oriented BP molecules at the\npolymer walls of the hexagonal microwells and at the top and bottom substrates.\nThis leads to an omni-directional stabilization of the entire BPLC system. This\nstudy not only provides a novel insight into the mechanism for the BP formation\nin the 2D microwell but also points to an improved route to stabilize BP using\n2D microwell arrays.",
        "positive": "Frustrated run and tumble of swimming E-coli bacteria in nematic liquid\n  crystals: In many situations bacteria move in complex environments, as for example in\nsoils, oceans or the human gut-track microbiome. In these natural environments,\ncarrier fluids such as mucus or reproductive fluids show complex structure\nassociated with non-Newtonian rheology. Many fundamental questions concerning\nthe the ability to navigate in such environments remain unsolved due to the\ninherent complexity of the natural surroundings. Recently, the interaction of\nswimming bacteria with nematic liquid crystals has attracted lot of attention.\nIn these structured fluids, the kinetics of bacterial motion is constrained by\nthe orientational molecular order of the liquid crystal (or director field) and\nnovel spatio-temporal patterns arise from this orientational constraint, as\nwell as from the interactions with topological defects. A question unaddressed\nso far is how bacteria are able to change swimming direction in such an\nenvironment. In this work, we study the swimming mechanism of a single\nbacterium, E. coli, constrained to move along the director field of a lyotropic\nchromonic liquid crystal (LCLC) that is confined to a planar cell. In such an\nenvironment, the spontaneous run and tumble motion of the bacterium gets\nfrustrated: the elasticity of the liquid crystal prevents flagella from\nunbundling. Interestingly, in order to change direction, bacteria execute a\nreversal motion along the director field, driven by the relocation of a single\nflagellum to the other side of the bacterial body, coined as a frustrated\ntumble. We present a detailed experimental characterization of this phenomenon,\nexploiting exceptional spatial and temporal resolution of bacteria and flagella\ndynamics during swimming, obtained using a two color Lagrangian tracking\ntechnique. We suggest a possible mechanism behind the frustrated run and tumble\nmotion, accounting for these observations."
    },
    {
        "anchor": "Length-Controlled Elasticity in 3D Fiber Networks: We present a model for disordered 3D fiber networks to study their linear and\nnonlinear elasticity over a wide range of network densities and fiber lengths.\nIn contrast to previous 2D models, these 3D networks with binary cross-links\nare under-constrained with respect to fiber stretching elasticity, suggesting\nthat bending may dominate their response. We find that such networks exhibit a\nfiber length-controlled bending regime and a crossover to a stretch-dominated\nregime for lengths beyond a characteristic scale that depends on the fiber's\nelastic properties. Finally, by extending the model to the nonlinear regime, we\nshow that these networks become intrinsically nonlinear with a vanishing linear\nresponse regime in the limit of floppy or long filaments.",
        "positive": "Heterogeneity and Low-Frequency Vibrations in Bidisperse Sphere Packings: In the jamming transition of monodisperse packings, spatial heterogeneity is\nirrelevant as the transition is described by mean-field theories. Here, we show\nthat this situation drastically changes if the particle-size dispersity is\nlarge enough. We use computer simulations to study the structural and\nvibrational properties of bidisperse sphere packings with a large size ratio.\nNear the critical point, the small particles tend to form clusters, leading to\nthe emergence of large-scale structural heterogeneity. Concomitantly, the\nlow-frequency vibrations are significantly enhanced compared to those in\nmonodisperse packings, and their density of states follows a linear law with\nthe frequency. We numerically and theoretically demonstrate that these\nbehaviors of the structural heterogeneity and the low-frequency vibrations are\nintimately connected. The present work suggests that the nature of\nheterogeneous packings is markedly different from that of homogeneous packings."
    },
    {
        "anchor": "New Approach on the General Shape Equation of Axisymmetric Vesicles: The general Helfrich shape equation determined by minimizing the curvature\nfree energy describes the equilibrium shapes of the axisymmetric lipid bilayer\nvesicles in different conditions. It is a non-linear differential equation with\nvariable coefficients. In this letter, by analyzing the unique property of the\nsolution, we change this shape equation into a system of the two differential\nequations. One of them is a linear differential equation. This equation system\ncontains all of the known rigorous solutions of the general shape equation. And\nthe more general constraint conditions are found for the solution of the\ngeneral shape equation.",
        "positive": "Cartan media: geometric continuum mechanics in homogeneous spaces: We present a geometric formulation of the mechanics of a field that takes\nvalues in a homogeneous space \\mathbb{X} on which a Lie group G acts\ntransitively. This generalises the mechanics of Cosserat media where \\mathbb{X}\nis the frame bundle of Euclidean space and G is the special Euclidean group.\nKinematics is described by a map from a space-time manifold to the homogeneous\nspace. This map is characterised locally by generalised strains (representing\nspatial deformations) and generalised velocities (representing temporal\nmotions). These are, respectively, the spatial and temporal components of the\nMaurer-Cartan one-form in the Lie algebra of G. Cartan's equation of structure\nprovides the fundamental kinematic relationship between generalised strains and\nvelocities. Dynamics is derived from a Lagrange-d'Alembert principle in which\ngeneralised stresses and momenta, taking values in the dual Lie algebra of G,\nare paired, respectively, with generalised strains and velocities. For\nconservative systems, the dynamics can be expressed completely through a\ngeneralised Euler-Poincare action principle. The geometric formulation leads to\naccurate and efficient structure-preserving integrators for numerical\nsimulations. We provide an unified description of the mechanics of Cosserat\nsolids, surfaces and rods using our formulation. We further show that, with\nsuitable choices of \\mathbb{X} and G, a variety of systems in soft condensed\nmatter physics and beyond can be understood as instances of a class of\nmaterials we provisionally call Cartan media."
    },
    {
        "anchor": "Spatio-temporal Characterization of Thermal Fluctuations in a\n  Non-turbulent Rayleigh-B\u00e9nard Convection at Steady State: In this paper we present a detailed description of the statistical and\ncomputational techniques that were employed to study a driven\nfar-from-equilibrium steady-state Rayleigh-B{\\'e}nard system in the\nnon-turbulent regime ($Ra\\leq 3500$). In our previous work on the\nRayleigh-B{\\'e}nard convection system we try to answer two key open problems\nthat are of great interest in contemporary physics: (i) how does an\nout-of-equilibrium steady-state differ from an equilibrium state and (ii) how\ndo we explain the spontaneous emergence of stable structures and simultaneously\ninterpret the physical notion of temperature when out-of-equilibrium. We\nbelieve that this paper will offer a useful repository of the technical details\nfor a first principles study of similar kind. In addition, we are also hopeful\nthat our work will spur considerable interest in the community which will lead\nto the development of more sophisticated and novel techniques to study\nfar-from-equilibrium behavior.",
        "positive": "Coarse-Grained Simulation of DNA using LAMMPS: During the last decade coarse-grained nucleotide models have emerged that\nallow us to DNA and RNA on unprecedented time and length scales. Among them is\noxDNA, a coarse-grained, sequence-specific model that captures the\nhybridisation transition of DNA and many structural properties of single- and\ndouble-stranded DNA. oxDNA was previously only available as standalone\nsoftware, but has now been implemented into the popular LAMMPS molecular\ndynamics code. This article describes the new implementation and analyses its\nparallel performance. Practical applications are presented that focus on\nsingle-stranded DNA, an area of research which has been so far\nunder-investigated. The LAMMPS implementation of oxDNA lowers the entry barrier\nfor using the oxDNA model significantly, facilitates future code development\nand interfacing with existing LAMMPS functionality as well as other\ncoarse-grained and atomistic DNA models."
    },
    {
        "anchor": "Observation of a crossover in kinetic aggregation of Palladium colloids: We use field emission scanning electron microscope (FE-SEM) to investigate\nthe growth of palladium colloids over the surface of thin films of WO3/glass.\nThe film is prepared by Pulsed Laser Deposition (PLD) at different\ntemperatures. A PdCl2 (aq) droplet is injected on the surface and in the\npresence of steam hydrogen the droplet is dried through a reduction reaction\nprocess. Two distinct aggregation regimes of palladium colloids are observed\nover the substrates. We argue that the change in aggregation dynamics emerges\nwhen the measured water drop Contact Angel (CA) for the WO3/glass thin films\npasses a certain threshold value, namely CA = 46 degrees, where a crossover in\nkinetic aggregation of palladium colloids occurs. Our results suggest that the\nmass fractal dimension of palladium aggregates follows a power-law behavior.\nThe fractal dimension (Df) in the fast aggregation regime, where the measured\nCA values vary from 27 up to 46 degrees, according to different substrate\ndeposition temperatures, is Df = 1.75 (0.02). This value of Df is in excellent\nagreement with kinetic aggregation of other colloidal systems in fast\naggregation regime. Whereas for the slow aggregation regime, with CA = 58\ndegrees, the fractal dimension changes abruptly to Df=1.92 (0.03). We have also\nused a modified Box-Counting method to calculate fractal dimension of\ngray-level images and observe that the crossover at around CA = 46 degrees\nremains unchanged.",
        "positive": "Stresses in Smooth Flows of Dense Granular Media: The form of the stress tensor is investigated in smooth, dense granular flows\nwhich are generated in split-bottom shear geometries. We find that, within a\nfluctuation fluidized spatial region, the form of the stress tensor is directly\ndictated by the flow field: The stress and strain-rate tensors are co-linear.\nThe effective friction, defined as the ratio between shear and normal stresses\nacting on a shearing plane, is found not to be constant but to vary throughout\nthe flowing zone. This variation can not be explained by inertial effects, but\nappears to be set by the local geometry of the flow field. This is in agreement\nwith a recent prediction, but in contrast with most models for slow grain\nflows, and points to there being a subtle mechanism that selects the flow\nprofiles."
    },
    {
        "anchor": "Simple ions control the elasticity of calcite gels via interparticle\n  forces: Suspensions of calcite in water are employed in many industrial fields such\nas paper filling, pharmaceutics, heritage conservation or building\nconstruction, where the rheological properties of the paste need to be\ncontrolled. We measure the impact of simple ions such as calcium, sodium or\nhydroxide on the elasticity of a nanocalcite paste, which behaves as a\ncolloidal gel. We confront our macroscopic measurements to DLVO interaction\npotentials, based on chemical speciations and measurements of the zeta\npotential. By changing the ion type and concentration, we go beyond the small\nrepulsion regime and span two orders of magnitude in shear modulus. Upon\naddition of calcium hydroxide, we observe a minimum in shear modulus,\ncorrelated to a maximum in the DLVO energy barrier, due to two competing\neffects: Calcium adsorption onto calcite surface rises the zeta potential and\nconsequently the electrostatic repulsion, while increasing salt concentration\ninduces stronger electrostatic screening. We also demonstrate that the addition\nof sodium hydroxide completely screens the surface charge and leads to a more\nrigid paste. A second important result is that carbonation of the calcite\nsuspensions by the atmospheric CO 2 leads to a convergent high elasticity of\nthe colloidal gels, whatever their initial value, also well rationalized by\nDLVO theory and resulting from a decrease in zeta potential and in surface\ncharge density.",
        "positive": "Elastic stabilisation of wrinkles in thin films by auxetic\n  microstructure: Thin elastic sheets and membranes are known to wrinkle when they are\nstretched -- the associated physics is highly non-linear. The mechanics of thin\nfilms that exhibit unusual behavior upon stretching, when they possess auxetic\nstructure, i.e. when their apparent Poisson's ratio is negative, is presented\nhere. Wrinkling is now suppressed within the bulk of auxetic films when\ntensioned, whereas localized creases confined to the clamps, that decay away\nexponentially, appear. These edge wrinkles are characterized for their\namplitude and wavelength experimentally, theoretically, and computationally,\nwhich show excellent agreement with expected trends. The scaling for amplitude,\nwavelength and decay rate upon film properties and tension is obtained using\nsimple analyses based on kinematic mismatch resulting from lateral Poisson's\nexpansion."
    },
    {
        "anchor": "Application of Projection Operator Method to Coarse-Grained Dynamics\n  with Transient Potential: We show that the coarse-grained dynamics model with the time-dependent and\nfluctuating potential (transient potential) can be derived from the microscopic\nHamiltonian dynamics. The concept of the transient potential was first\nintroduced rather phenomenologically, and its relation to the underlying\nmicroscopic dynamics has not been clarified yet. This is in contrast to the\ngeneralized Langevin equation, of which relation to the microscopic dynamics is\nwell-established. In this work, we show that the dynamic equations with the\ntransient potential can be derived for the coupled oscillator model, without\nany approximations. It is known that the dynamics of the coupled oscillator\nmodel can be exactly described by the generalized Langevin type equations. This\nfact implies that the dynamic equations with the transient potential can be\nutilized as a coarse-grained dynamics model in a similar way to the generalized\nLangevin equation. Then we show that the dynamic equations for the transient\npotential can be also formally derived for the microscopic Hamiltonian\ndynamics, without any approximations. We use the projection operator method for\nthe coarse-grained variables and transient potential. The dynamic equations for\nthe coarse-grained positions and momenta are similar to those in the\nHamiltonian dynamics, but the interaction potential is replaced by the\ntransient potential. The dynamic equation for the transient potential is the\ngeneralized Langevin equation with the memory effect. Our result justifies the\nuse of the transient potential to describe the coarse-grained dynamics. We\npropose several approximations to obtain simplified dynamics model. We show\nthat, under several approximations, the dynamic equation for the transient\npotential reduces to the relatively simple Markovian dynamic equation for the\npotential parameters.",
        "positive": "Nanoparticles Binding to Lipid Membranes: from Vesicle-Based Gels to\n  Vesicle Inversion and Destruction: Cells offer numerous inspiring examples where proteins and membranes combine\nto form complex structures that are key to intracellular compartmentalization,\ncargo transport, and specialization of cell morphology. Despite this wealth of\nexamples, we still lack the design principles to control membrane morphology in\nsynthetic systems. Here we show that even the relatively simple case of\nspherical nanoparticles binding to lipid-bilayer membrane vesicles results in a\nremarkably rich set of morphologies that can be controlled quantitatively via\nthe particle binding energy. We find that when the binding energy is weak\nrelative to a characteristic membrane-bending energy, the vesicles adhere to\none another and form a soft solid, which could be used as a useful platform for\ncontrolled release. When the binding energy is larger, the vesicles undergo a\nremarkable destruction process consisting first of invaginated tubules,\nfollowed by vesicles turning inside-out, yielding a network of\nnanoparticle-membrane tubules. We propose that the crossover from one behavior\nto the other is triggered by the transition from partial to complete wrapping\nof nanoparticles. This model is confirmed by computer simulations and by\nquantitative estimates of the binding energy. These findings open the door to a\nnew class of vesicle-based, closed-cell gels that are more than 99% water and\ncan encapsulate and release on demand. Our results also show how to\nintentionally drive dramatic shape changes in vesicles as a step toward\nshape-responsive particles. Finally, they help us to unify the wide range of\npreviously observed responses of vesicles and cells to added nanoparticles."
    },
    {
        "anchor": "Finsler geometry modeling and Monte Carlo study of 3D liquid crystal\n  elastomer: We study a three-dimensional ($3D$) liquid crystal elastomer (LCE) in the\ncontext of Finsler geometry (FG) modeling, where FG is a mathematical framework\nfor describing anisotropic phenomena. The LCE is a $3D$ rubbery object and has\nremarkable properties, such as the so-called soft elasticity and elongation,\nthe mechanisms of which are unknown at present. To understand these anisotropic\nphenomena, we introduce a variable $\\sigma$, which represents the directional\ndegrees of freedom of a liquid crystal (LC) molecule. This variable $\\sigma$ is\nused to define the Finsler metric for the interaction between the LC molecules\nand bulk polymers. Performing Monte Carlo (MC) simulations for a cylindrical\nbody between two parallel plates, we numerically find the soft elasticity in MC\ndata such that the tensile stress and strain are consistent with reported\nexperimental results. Moreover, the elongation is also observed in the results\nof MC simulations of a spherical body with free boundaries, and the data\nobtained from the MC simulations are also consistent with existing experimental\nresults.",
        "positive": "Directional motion of forced polymer chains with hydrodynamic\n  interaction: We study the propulsion of a one-dimensional (1D) polymer chain under\nsinusoidal external forces in the overdamped (low Reynolds number) regime. We\nshow that, when hydrodynamical interactions are included, the polymer presents\ndirectional motion which depends on the phase differences of the external force\napplied along the chain. Moreover, the velocity shows a maximum as a function\nof the frequency. We discuss the relevance of all these results in light of\nrecent nanotechnology experiments."
    },
    {
        "anchor": "High Dimensional Fluctuations in Liquid Water: Combining Chemical\n  Intuition with Unsupervised Learning: The microscopic description of the local structure of water remains an open\nchallenge. Here, we adopt an agnostic approach to understanding water's\nhydrogen bond network using data harvested from molecular dynamics simulations\nof an empirical water model. A battery of state-of-the-art unsupervised\ndata-science techniques are used to characterize the free energy landscape of\nwater starting from encoding the water environment using local-atomic\ndescriptors, through dimensionality reduction and finally the use of advanced\nclustering techniques. Analysis of the free energy at ambient conditions was\nfound to be consistent with a rough single basin and independent of the choice\nof the water model. We find that the fluctuations of the water network occur in\na high-dimensional space which we characterize using a combination of both\natomic descriptors and chemical-intuition based coordinates. We demonstrate\nthat a combination of both types of variables are needed in order to adequately\ncapture the complexity of the fluctuations in the hydrogen bond network at\ndifferent length-scales both at room temperature and also close to the critical\npoint of water. Our results provide a general framework for examining\nfluctuations in water under different conditions.",
        "positive": "Electrocrystallization of Supercooled Water Confined by Graphene Walls: Any structural transformation of water is sensitive to an external electric\nfield, since water molecules have dipole moments. We study influence of\nexternal uniform electric field on crystallization of supercooled water\nenclosed between two graphene planes. Crystallization of such the system is\ncaused by ordinary relaxation of the metastable phase into an ordered\n(crystalline) phase and by dipole alignment induced by an applied electric\nfield. We found that this system at the temperature $T=268$ K, where water has\nthe density $0.94$ g/cm$^3$ and the applied electric field is of the magnitude\n$E=0.5~\\textrm{V}$/Angstrom, crystallizes into the cubic ice with few the\ndefects, and the crystallization proceeds over the time scale $\\sim 5.0$ ns.\nThe obtained results can be directly used to develop the methods to drive by\nwater crystallization."
    },
    {
        "anchor": "Many-body effects for critical Casimir forces: Within mean-field theory we calculate the scaling functions associated with\ncritical Casimir forces for a system consisting of two spherical colloids\nimmersed in a binary liquid mixture near its consolute point and facing a\nplanar, homogeneous substrate. For several geometrical arrangements and\nboundary conditions we analyze the normal and the lateral critical Casimir\nforces acting on one of the two colloids. We find interesting features such as\na change of sign of these forces upon varying either the position of one of the\ncolloids or the temperature. By subtracting the pairwise forces from the total\nforce we are able to determine the many-body forces acting on one of the\ncolloids. We have found that the many-body contribution to the total critical\nCasimir force is more pronounced for small colloid-colloid and\ncolloid-substrate distances, as well as for temperatures close to criticality,\nwhere the many-body contribution to the total force can reach up to 25%.",
        "positive": "Slow relaxation and aging phenomena at nano-scale in granular materials: Complex systems having metastable elements often demonstrate nearly log-time\nrelaxations and a kind of aging: repeated stimuli weaken the system's\nrelaxational response. Granular matter is known to exhibit a wealth of such\nbehaviors, for which the role of thermal fluctuations is usually ignored.\nHowever, we demonstrate that the latter can pronouncedly affect contacting\nmesoscopic-scale asperities and be macroscopically observed via appropriate\nacoustic effects. We also propose a mechanism comprising slow relaxations and\naging as intrinsic properties of a wide class of systems with metastable\nstates."
    },
    {
        "anchor": "Extended free-energy functionals for achiral and chiral ferroelectric\n  nematic liquid crystals: Polar nematic liquid crystals are new classes of condensed-matter states\nwhere the inversion symmetry common to the traditional apolar nematics is\nbroken. Establishing theoretical descriptions for the novel phase states is an\nurgent task. Here, we develop a Landau-type mean-field theory for both the\nachiral and chiral ferroelectric nematics. In the polar nematic states, the\ninversion symmetry breaking adds two new contributions: an additional odd\nelastic term (corresponding to the flexoelectricity in symmetry) to the\nstandard Oseen-Frank free energy and an additional Landau term relating to the\ngradient of local polarisation. As a general necessity, the coupling between\nthe scalar order parameter and polarisation order is further considered. In the\nchiral and polar nematic state, we reveal that the competition between the\ntwist elasticity and polarity dictates effective compressive energy arising\nfrom the quasi-layer structure. The polarisation gradient is an essential term\nfor describing the ferroelectric nature of the systems. The approaches provide\ntheoretical foundations for testing and predicting polar structures in emerging\npolar liquid crystals.",
        "positive": "Test of the semischematic model for a liquid of linear molecules: We apply to a liquid of linear molecules the semischematic mode-coupling\nmodel, previously introduced to describe the center of mass (COM) slow dynamics\nof a network-forming molecular liquid. We compare the theoretical predictions\nand numerical results from a molecular dynamics simulation, both for the time\nand the wave-vector dependence of the COM density-density correlation function.\nWe discuss the relationship between the presented analysis and the results from\nan approximate solution of the equations from molecular mode-coupling theory\n[R. Schilling and T. Scheidsteger, Phys. Rev. E 56 2932 (1997)]."
    },
    {
        "anchor": "Dimensional crossover in fragmentation: Experiments in which thick clay plates and glass rods are fractured have\nrevealed different behavior of fragment mass distribution function in the small\nand large fragment regions. In this paper we explain this behavior using\nnon-extensive Tsallis statistics and show how the crossover between the two\nregions is caused by the change in the fragments' dimensionality during the\nfracture process. We obtain a physical criterion for the position of this\ncrossover and an expression for the change in the power law exponent between\nthe small and large fragment regions. These predictions are in good agreement\nwith the experiments on thick clay plates",
        "positive": "Kinetics of copolymer localization at a selective liquid-liquid\n  interface: The localization kinetics of a regular block-copolymer of total length $N$\nand block size $M$ at a selective liquid-liquid interface is studied in the\nlimit of strong segregation between hydrophobic and polar segments in the\nchain. We propose a simple analytic theory based on scaling arguments which\ndescribes the relaxation of the initial coil into a flat-shaped layer for the\ncases of both Rouse and Zimm dynamics. For Rouse dynamics the characteristic\ntimes for attaining equilibrium values of the gyration radius components\nperpendicular and parallel to the interface are predicted to scale with block\nlength $M$ and chain length $N$ as $\\tau_{\\perp} \\propto M^{1+2\\nu}$ (here\n$\\nu\\approx 0.6$ is the Flory exponent) and as $\\tau_{\\parallel} \\propto N^2$,\nalthough initially the characteristic coil flattening time is predicted to\nscale with block size as $\\propto M$. Since typically $N\\gg M$ for multiblock\ncopolymers, our results suggest that the flattening dynamics proceeds faster\nperpendicular rather than parallel to the interface, in contrast to the case of\nZimm dynamics where the two components relax with comparable rate, and proceed\nconsiderably slower than in the Rouse case.\n  We also demonstrate that, in the case of Rouse dynamics, these scaling\npredictions agree well with the results of Monte Carlo simulations of the\nlocalization dynamics. A comparison to the localization dynamics of {\\em\nrandom} copolymers is also carried out."
    },
    {
        "anchor": "Long time viscosity of dilute magnetorheological dispersions under\n  periodic magnetic perturbations: The effect of periodic magnetic perturbations on the rheological properties\nof a low concentration magnetorheological dispersion is studied experimentally.\nIt is found that an important increment in the measured viscosity occurs when\nin addition to a static field a magnetic periodic perturbation is applied. The\nmagnitude of these changes depend on the amplitude and frequency of the\nperturbation as well as on the simultaneity of the application of the static\nfield and the perturbation. These findings are discussed in terms of the\nobserved rearrangement of the cluster structure in the dispersion.",
        "positive": "Clustering of Self-Propelled Triangles with Surface Roughness: Self-propelled particles can spontaneously form dense phases from a dilute\nsuspension in a process referred to as motility-induced phase separation. The\nproperties of the out-of-equilibrium structures that are formed are governed by\nthe specifics of the particle interactions and the strength of the activity.\nThus far, most studies into the formation of these structures have focused on\nspherical colloids, dumbbells, and rod-like particles endowed with various\ninteraction potentials. Only a few studies have examined the collective\nbehavior of more complex particle shapes. Here, we increase the geometric\ncomplexity and use Molecular Dynamics simulations to consider the structures\nformed by triangular self-propelled particles with surface roughness. These\ntriangles either move towards their apex or towards their base, i.e., they\npossess a polarity. We find that apex-directed triangles cluster more readily,\nmore stably, and have a smoother cluster interface than their base-directed\ncounterparts. A difference between the two polarities is in line with the\nresults of [H.H. Wensink, et al., Phys. Rev. E 89, 010302(R) (2014)], however,\nwe obtain the reversed result when it comes to clustering, namely that\napex-directed particles cluster more readily. We further show that reducing the\nsurface roughness negatively impacts the stability of the base-directed\nstructures, suggesting that their formation is in large part due to surface\nroughness. Our results lay a solid foundation for future experimental and\ncomputational studies into the effect of roughness on the collective dynamics\nof swimmers."
    },
    {
        "anchor": "Spreading on viscoelastic solids: Are contact angles selected by\n  Neumann's law?: The spreading of liquid drops on soft substrates is extremely slow, owing to\nstrong viscoelastic dissipation inside the solid. A detailed understanding of\nthe spreading dynamics has remained elusive, partly owing to the difficulty in\nquantifying the strong viscoelastic deformations below the contact line that\ndetermine the shape of moving wetting ridges. Here we present direct\nexperimental visualisations of the dynamic wetting ridge, complemented with\nmeasurements of the liquid contact angle. It is observed that the wetting ridge\nexhibits a rotation that follows exactly the dynamic liquid contact angle -- as\nwas previously hypothesized [Karpitschka \\emph{et al.} Nature Communications\n\\textbf{6}, 7891 (2015)]. This experimentally proves that, despite the contact\nline motion, the wetting ridge is still governed by Neumann's law. Furthermore,\nour experiments suggest that moving contact lines lead to a variable surface\ntension of the substrate. We therefore set up a new theory that incorporates\nthe influence of surface strain, for the first time including the so-called\nShuttleworth effect into the dynamical theory for soft wetting. It includes a\ndetailed analysis of the boundary conditions at the contact line, complemented\nby a dissipation analysis, which shows, again, the validity of Neumann's\nbalance.",
        "positive": "Controlling Gaussian and mean curvatures at microscale by sublimation\n  and condensation of smectic liquid crystals: Soft materials with layered structure such as membranes, block copolymers,\nand smectics exhibit intriguing morphologies with nontrivial curvatures. We\nreport on restructuring the Gaussian and mean curvatures of smectic A films\nwith free surface in the process of sintering, i.e. reshaping at elevated\ntemperatures. The pattern of alternating patches of negative, zero, and\npositive mean curvature of the air-smectic interface has a profound effect on\nthe rate of sublimation. As a result of sublimation, condensation, and\nrestructuring, initially equilibrium smectic films with negative and zero\nGaussian curvature are transformed into structures with pronounced positive\nGaussian curvature of layers packing, seldom seen in samples obtained by\ncooling from the isotropic melt. The observed relationship between the\ncurvatures, bulk elastic behaviour, and interfacial geometries in sintering of\nsmectic liquid crystals paves the way for new approaches to control soft\nmorphologies at micron and submicron scales."
    },
    {
        "anchor": "Gellation of rigid filament networks: We consider a model for gelation of rigid rods, in which rods that are\ninitially placed at random undergo diffusion, and form cross-links when they\ncollide. In the limit of point-like cross-links, the number N of croslinks per\nrod approaches N ~ 3.53. In a model with compliant cross-links of maximum\nlength l_c, N(t) increases with time as N(t) ~ const. + cL^2 l_c ln(t), where c\nis concentration and L is rod length.",
        "positive": "Effect of Topology on the Conformations of Ring Polymers: The bond fluctuation method is used to simulate both non-concatenated\nentangled and interpenetrating melts of ring polymers. We find that the\nswelling of interpenetrating rings upon dilution follows the same laws as for\nlinear chains. Knotting and linking probabilities of ring polymers in\nsemi-dilute solution are analyzed using the HOMFLY polynomial. We find an\nexponential decay of the knotting probability of rings. The correlation length\nof the semi-dilute solution can be used to superimpose knotting data at\ndifferent concentrations. A power law dependence $f_{n}\\sim\\phi\nR^{2}\\sim\\phi^{0.77}N$ for the average number $f_{n}$ of linked rings per ring\nat concentrations larger than the overlap volume fraction of rings $\\phi^{*}$\nis determined from the simulation data. The fraction of non-concatenated rings\ndisplays an exponential decay $P_{OO}\\sim\\exp(-f_{n})$, which indicates $f_{n}$\nto provide the entropic effort for not forming concatenated conformations.\nBased upon this results we find four different regimes for the conformations of\nrings in melts that are separated by a critical lengths $N_{OO}$, $N_{C}$ and\n$N^{*}$. $N_{OO}$ describes the onset of the effect of non-concatenation below\nwhich topological effects are not important, $N_{C}$ is the cross-over between\nweak and strong compression of rings, and $N^{*}$ is defined by the cross-over\nfrom a non-concatenation contribution $f_{n}\\sim\\phi R^{2}$ to an overlap\ndominated concatenation contribution $f_{n}\\sim\\phi N^{1/2}$ at $N>N^{*}$. For\n$N_{OO}<N<N_{C}$, the scaling of ring sizes $R\\sim N^{2/5}$ results from\nbalancing non-concatenation with weak compression of rings. For\n$N_{C}<N<N^{*}$, non-concatenation and strong compression imply $R\\sim\nN^{3/8}$. Our simulation data for non-interpenetrating rings up to $N=1024$ are\nin good agreement with the prediction for weakly compressed rings."
    },
    {
        "anchor": "Ionic Screening and Dissociation are Crucial for Understanding Chemical\n  Self-Propulsion in Water: Water is a polar solvent and hence supports the bulk dissociation of itself\nand its solutes into ions, and the re-association of these ions into neutral\nmolecules in a dynamic equilibrium, e.g., ${\\rm H_2O_2}\\leftrightharpoons {\\rm\nH^+~+~HO_2^-}$. Using continuum theory, we study the influence of these\nreactions on the self-propulsion of colloids driven by surface chemical\nreactions (chemical swimmers) in aqueous solution. The association-dissociation\nreactions are here shown to have a strong influence on the swimmers' behaviour,\nand must therefore be included in future modelling. In particular, such bulk\nreactions permit charged swimmers to propel electrophoretically even if all\nspecies involved in the surface reactions are neutral. The bulk reactions also\nsignificantly modify the predicted speed of chemical swimmers propelled by\nionic currents, by up to an order of magnitude. For swimmers whose surface\nreactions produce both anions and cations (ionic self-diffusiophoresis), the\nbulk reactions produce an additional reactive screening length, analogous to\nthe Debye length in electrostatics. This in turn leads to an inverse\nrelationship between swimmer radius and swimming speed, which could provide an\nalternative explanation for recent experimental observations on Pt-polystyrene\nJanus swimmers [S. Ebbens et al., Phys. Rev. E 85, 020401 (2012)]. We also use\nour continuum theory to investigate the effect of the Debye screening length\nitself, going beyond the infinitely thin limit approximation used by previous\nanalytical theories. We identify significant departures from this limiting\nbehavior for micron-sized swimmers under typical experimental conditions, and\nfind that the limiting behavior fails entirely for nanoscale swimmers.",
        "positive": "Extensibility governs the flow-induced alignment of polymers and\n  rod-like colloids: Polymers and rod-like colloids (PaRC) adopt a favorable orientation under\nsufficiently strong flows. However, how the flow kinematics affect the\nalignment of such nanostructures according to their extensibility remains\nunclear. By analysing the shear- and extension-induced alignment of chemically\nand structurally different PaRC, we show that extensibility is a key\ndeterminant of the structural response to the imposed kinematics. We propose a\nunified description of the effectiveness of extensional flow, compared to\nshearing flow, at aligning PaRC of different extensibility."
    },
    {
        "anchor": "Kinetic signature of cooperativity in the irreversible collapse of a\n  polymer: We investigate the kinetics of a polymer collapse due to the formation of\nirreversible crosslinks between its monomers. Using the contact probability\n$P(s)$ as a scale-dependent order parameter depending on the chemical distance\n$s$, our simulations show the emergence of a cooperative pearling instability.\nNamely, the polymer undergoes a sharp conformational transition to a set of\nabsorbing states characterized by a length scale $\\xi$ corresponding to the\nmean pearl size. This length and the transition time depend on the polymer\nequilibrium dynamics and the crosslinking rate. We confirm experimentally this\ntransition using a DNA conformation capture experiment in yeast.",
        "positive": "Non-Affine Displacements and the Non-Linear Response of a Strained\n  Amorphous Solid: We demonstrate that irreversible structural reorganization is not necessary\nfor the observation of yield behaviour in an amorphous solid. While the\nmajority of solids strained to their yield point do indeed undergo an\nirreversible reorganization, we find a significant fraction of solids exhibit\nyield via a reversible strain. We also demonstrate that large instantaneous\nstrains in excess of the yield stress can result in complete stress relaxation,\na result of the large non-affine motions driven by the applied strain. The\nempirical similarity of the dependence of the ratio of stress over strain on\nthe non-affine mean squared displacement with that for the shear modulus\nobtained from quiescent liquid at non-zero temperature supports the proposition\nthat rigidity depends on the size of the sampled configurational space only,\nand is insensitive as to how this space is sampled."
    },
    {
        "anchor": "Excess Vibrational Modes and the Boson Peak in Model Glasses: The excess low-frequency normal modes for two widely-used models of glasses\nwere studied at zero temperature. The onset frequencies for the anomalous modes\nfor both systems agree well with predictions of a variational argument, which\nis based on analyzing the vibrational energy originating from the excess\ncontacts per particle over the minimum number needed for mechanical stability.\nEven though both glasses studied have a high coordination number, most of the\nadditional contacts can be considered to be weak.",
        "positive": "Collective modes and gapped momentum states in liquid Ga: experiment,\n  theory and simulation: Collective excitations in liquids are important for understanding liquid\ndynamical and thermodynamic properties. Gapped momentum states (GMS) are a\nnotable feature of liquid dynamics predicted to operate in the transverse\nsector of collective excitations. Here, we combine inelastic neutron scattering\nexperiments, theory and molecular dynamics modelling to study collective\nexcitations and GMS in liquid Ga in a wide range of temperature and $k$-points.\nWe find that all three lines of enquiry agree for the longitudinal sector of\nliquid dynamics. In the transverse sector, the experiments agree with theory,\nmodelling as well as earlier X-ray experiments at larger $k$, whereas theory\nand modelling agree in a wide range of temperature and $k$-points. We observe\nthe emergence and development of the $k$-gap in the transverse sector which\nincreases with temperature and inverse of relaxation time as predicted\ntheoretically."
    },
    {
        "anchor": "Surface tensions, surface potentials and the Hofmeister series of\n  electrolyte solutions: A theory is presented which allows us to accurately calculate the surface\ntensions and the surface potentials of electrolyte solutions. Both the ionic\nhydration and the polarizability are taken into account. We find a good\ncorrelation between the Jones-Dole viscosity $B$-coefficient and the ionic\nhydration near the air-water interface. The kosmotropic anions such as\nfluoride, iodate, sulfate and carbonate, are found to be strongly hydrated and\nare repelled from the interface. The chaotropic anions such as perchlorate,\niodide, chlorate and bromide are found to be significantly adsorbed to the\ninterface. Chloride and bromate anions become weakly hydrated in the\ninterfacial region. The sequence of surface tensions and surface potentials is\nfound to follow the Hofmeister ordering. The theory, with only one adjustable\nparameter, quantitatively accounts for the surface tensions of 10 sodium salts\nfor which there is experimental data.",
        "positive": "Non-Equilibrium relation between mobility and diffusivity of interacting\n  Brownian particles under shear: We investigate the relation between mobility and diffusivity for Brownian\nparticles under steady shear near the glass transition, using mode coupling\napproximations. For the two directions perpendicular to the shear direction,\nthe particle motion is diffusive at long times and the mobility reaches a\nfinite constant. Nevertheless, the Einstein relation holds only for the\nshort-time in-cage motion and is violated for long times. In order to get the\nrelation between diffusivity and mobility, we perform the limit of small\nwavevector for the relations derived previously [Phys. Rev. Lett. 102 (2009),\n135701], without further approximation. We find good agreement to simulation\nresults. Furthermore, we split the extra term in the mobility in an exact way\ninto three terms. Two of them are expressed in terms of mean squared\ndisplacements. The third is given in terms of the (less handy) force-force\ncorrelation function."
    },
    {
        "anchor": "Topological Bounds of Bending Energy for Lipid Vesicles: The Helfrich bending energy plays an important role in providing a mechanism\nfor the conformation of a lipid vesicle in theoretical biophysics, which is\ngoverned by the principle of energy minimization over configurations of\nappropriate topological characteristics. We will show that the presence of a\nquantity called the spontaneous curvature obstructs the existence of a\nminimizer of the Helfrich energy over the set of embedded ring tori. Besides,\ndespite the well-realized knowledge that lipid vesicles may present themselves\nin a variety of shapes of complicated topology, there is a lack of topological\nbounds for the Helfrich energy. To overcome these difficulties, we consider a\ngeneral scale-invariant anisotropic curvature energy that extends the Canham\nelastic bending energy developed in modeling a biconcave-shaped red blood cell.\nWe will show that, up to a rescaling of the generating radii, there is a unique\nminimizer of the energy over the set of embedded ring tori, in the entire\nparameter regime, which recovers the Willmore minimizer in its Canham isotropic\nlimit. We also show how elevated anisotropy favors energetically a clear\ntransition from spherical-, to ellipsoidal-, and then to biconcave-shaped\nsurfaces, for a lipid vesicle. We then establish some genus-dependent\ntopological lower and upper bounds for the anisotropic energy. Finally, we\nderive the shape equation of the generalized bending energy, which extends the\nwell-known Helfrich shape equation.",
        "positive": "Shapes of a filament on the surface of a bubble: The shape assumed by a slender elastic structure is a function both of the\ngeometry of the space in which it exists and the forces it experiences. We\nexplore by experiments and theoretical analysis, the morphological phase-space\nof a filament confined to the surface of a spherical bubble. The morphology is\ncontrolled by varying bending stiffness and weight of the filament, and its\nlength relative to the bubble radius. When the dominant considerations are\ngeometry of confinement and elastic energy, the filament lies along a geodesic\nand when gravitational energy becomes significant, a bifurcation occurs, with a\npart of the filament occupying a longitude and the rest along a curve\napproximated by a latitude. Far beyond the transition, when the filament is\nmuch longer than the diameter, it coils around the selected latitudinal region.\nA simple model with filament shape as a composite of two arcs captures the\ntransition well and for better quantitative agreement with the subcritical\nnature of bifurcation, we study the morphology by numerical energy\nminimization. Our analysis of filament's morphological space spanned by a\ngeometric parameter, and one that compares elastic energy with body forces, may\nprovide guidance for packing slender structures on complex surfaces."
    },
    {
        "anchor": "Structure and dynamics of hydrodynamically interacting finite-size\n  Brownian particles in a spherical cavity: spheres and cylinders: The structure and dynamics of confined suspensions of particles of arbitrary\nshape is of interest in multiple disciplines, from biology to engineering.\nTheoretical studies are often limited by the complexity of long-range\nparticle-particle and particle-wall forces, including many-body fluctuating\nhydrodynamic interactions. Here, we report a computational study on the\ndiffusion of spherical and cylindrical particles confined in a spherical\ncavity. We rely on an Immersed-Boundary General geometry Ewald-like method to\ncapture lubrication and long-range hydrodynamics, and include appropriate\nnon-slip conditions at the confining walls. A Chebyshev polynomial\napproximation is used to satisfy the fluctuation-dissipation theorem for the\nBrownian suspension. We explore how lubrication, long-range hydrodynamics,\nparticle volume fraction and shape affect the equilibrium structure and the\ndiffusion of the particles. It is found that once the particle volume fraction\nis greater than $10\\%$, the particles start to form layered aggregates that\ngreatly influence particle dynamics. Hydrodynamic interactions strongly\ninfluence the particle diffusion by inducing spatially dependent short-time\ndiffusion coefficients, stronger wall effects on the particle diffusion towards\nthe walls, and a sub-diffusive regime --caused by crowding-- in the long-time\nparticle mobility. The level of asymmetry of the cylindrical particles\nconsidered here is enough to induce an orientational order in the layered\nstructure, decreasing the diffusion rate and facilitating a transition to the\ncrowded mobility regime at low particle concentrations. Our results offer\nfundamental insights into the diffusion and distribution of globular and\nfibrillar proteins inside cells.",
        "positive": "Controllable matter-wave switchers with vector Bose-Einstein solitons: We show the possibility of producing matter-wave switching devices by using\nManakov interactions between matter wave solitons in two-species Bose-Einstein\nCondensates (BEC). Our results establish the experimental parameters for three\ninteraction regimes in two-species BECs: symmetric and asymmetric splitting,\ndown-switching and up-switching. We have studied the dependence upon the\ninitial conditions and the kind of interaction between the two components of\nthe BECs."
    },
    {
        "anchor": "Understanding Contagion Dynamics through Microscopic Processes in Active\n  Brownian Particles: Together with the universally recognized SIR model, several approaches have\nbeen employed to understand the contagious dynamics of interacting particles.\nHere, Active Brownian particles (ABP) are introduced to model the contagion\ndynamics of living agents that spread an infectious disease in space and time.\nSimulations were performed for several population densities and contagious\nrates. Our results show that ABP not only reproduces the time dependence\nobserved in traditional SIR models, but also allows us to explore the critical\ndensities, contagious radius, and random recovery times that facilitate the\nvirus spread. Furthermore, we derive a first-principles analytical expression\nfor the contagion rate in terms of microscopic parameters, without the\nassumption of free parameters as the classical SIR-based models. This approach\noffers a novel alternative to incorporate microscopic processes into the\nanalysis of SIR-based models with applications in a wide range of biological\nsystems",
        "positive": "Tuning the bulk properties of bidisperse granular mixtures by small\n  amount of fines: We study the bulk properties of isotropic bidisperse granular mixtures using\ndiscrete element simulations. The focus is on the influence of the size\n(radius) ratio of the two constituents and volume fraction on the mixture\nproperties. We show that the effective bulk modulus of a dense granular (base)\nassembly can be enhanced by up to 20% by substituting as little as 5% of its\nvolume with smaller sized particles. Particles of similar sizes barely affect\nthe macroscopic properties of the mixture. On the other extreme, when a huge\nnumber of fine particles are included, most of them lie in the voids of the\nbase material, acting as rattlers, leading to an overall weakening effect. In\nbetween the limits, an optimum size ratio that maximizes the bulk modulus of\nthe mixture is found. For loose systems, the bulk modulus decreases\nmonotonically with addition of fines regardless of the size ratio. Finally, we\nrelate the mixture properties to the 'typical' pore size in a disordered\nstructure as induced by the combined effect of operating volume fraction\n(consolidation) and size ratio."
    },
    {
        "anchor": "PyMembrane: A flexible framework for efficient simulations of elastic\n  and liquid membranes: PyMembrane is a software package for simulating liquid and elastic membranes\nusing a discretisation of the continuum description based on unstructured\ntriangulated two-dimensional meshes embedded in three-dimensional space. The\npackage is written in C++, with a flexible and intuitive Python interface,\nallowing for a quick setup, execution and analysis of complex simulations.\nPyMembrane follows modern software engineering principles and features a\nmodular design that allows for straightforward implementation of custom\nextensions while ensuring consistency and enabling inexpensive maintenance. A\nhallmark feature of this design is the use of a standardized C++ interface\nwhich streamlines adding new functionalities. Furthermore, PyMembrane uses data\nstructures optimised for unstructured meshes, ensuring efficient mesh\noperations and force calculations. By providing several templates for typical\nsimulations supplemented by extensive documentation, the users can seamlessly\nset up and run research-level simulations and extend the package to integrate\nadditional features, underscoring PyMembrane's commitment to user-centric\ndesign.",
        "positive": "Analysis of the general uncertainty propagation and calculation of the\n  systematic uncertainty of the Neumann Equation of State for surface free\n  energy determination: The determination of the surface free energy $\\gamma_{\\text{SV}}$ of solid\nmaterials provides information to explain and understand a wide variety of\nphenomena in surface science. One of the most widely used methods to determine\nthe value of $\\gamma_{\\text{SV}}$ is the Neumann equation of state (EQS), whose\napplication requires the values of the contact angle $(\\theta)$ and the surface\ntension of a probe liquid $\\gamma_{\\text{LV}}$. Both parameters are determined\nexperimentally, and their values may be subject to considerable uncertainty. In\nthe present work, the uncertainties of the EQS are analyzed by means of the\nTaylor series method, using a polynomial adjustment to the EQS previously\nreported. This analysis allowed us to determine the effects of the ${\\theta}$\nand $\\gamma_{\\text{LV}}$ uncertainties on $\\gamma_{\\text{SV}}$ values. The\n$\\gamma_{\\text{SV}}$ of polyoxymethylene (POM) and polytetrafluoroethylene\n(PTFE) was calculated using the EQS from four probe liquids and taking into\naccount the propagation of the ${\\theta}$ and $\\gamma_{\\text{LV}}$\nuncertainties. Generally, the comparison of the $\\gamma_{\\text{SV}}$ values\ncalculated from the different probe fluids revealed significant differences. As\na solution to this inconsistency in the EQS method, we proposed taking into\naccount a systematic standard uncertainty associated with the method equal to\n$1.3 \\, \\text{mJ/m}^2$ . This allowed the differences between the\n$\\gamma_{\\text{SV}}$ values for the different probe liquids to be\nnon-significant and therefore the method to be consistent."
    },
    {
        "anchor": "Theory of asymmetric non-additive binary hard-sphere mixtures: We show that the formal procedure of integrating out the degrees of freedom\nof the small spheres in a binary hard-sphere mixture works equally well for\nnon-additive as it does for additive mixtures. For highly asymmetric mixtures\n(small size ratios) the resulting effective Hamiltonian of the one-component\nfluid of big spheres, which consists of an infinite number of many-body\ninteractions, should be accurately approximated by truncating after the term\ndescribing the effective pair interaction. Using a density functional treatment\ndeveloped originally for additive hard-sphere mixtures we determine the zero,\none, and two-body contribution to the effective Hamiltonian. We demonstrate\nthat even small degrees of positive or negative non-additivity have significant\neffect on the shape of the depletion potential. The second virial coefficient\n$B_2$, corresponding to the effective pair interaction between two big spheres,\nis found to be a sensitive measure of the effects of non-additivity. The\nvariation of $B_2$ with the density of the small spheres shows significantly\ndifferent behavior for additive, slightly positive and slightly negative\nnon-additive mixtures. We discuss the possible repercussions of these results\nfor the phase behavior of binary hard-sphere mixtures and suggest that\nmeasurements of $B_2$ might provide a means of determining the degree of\nnon-additivity in real colloidal mixtures.",
        "positive": "Two Experimental Tests of the Halperin-Lubensky-Ma Effect at the\n  Nematic-Smectic-A Phase Transition: We have conducted two quantitative tests of predictions based on the\nHalperin-Lubensky-Ma (HLM) theory of fluctuation-induced first-order phase\ntransitions. First, we explore the effect of an external magnetic field on the\nnematic-smectic-A (NA) transition in a liquid crystal. Second, we examine the\ndependence of the first-order discontinuity as a function of mixture\nconcentration in pure 8CB and three 8CB-10CB mixtures. We find the first\nquantitative evidence for deviations from the HLM theory."
    },
    {
        "anchor": "Fine structures of Intrinsically Disordered Proteins: We report simulation studies of 33 single intrinsically disordered proteins\n(IDPs) using coarse-grained (CG) bead-spring models where interactions among\ndifferent amino acids are introduced through a hydropathy matrix and additional\nscreened Coulomb interaction for the charged amino acid beads. Our simulation\nstudies of two different hydropathy scales (HPS1, HPS2) [Dignon et al., PLOS\nComp. Biology, 14, 2018, Tesei et al. PNAS, 118, 2021] and the comparison with\nthe existing experimental data indicates an optimal interaction parameter\n$\\epsilon = 0.1$ kcal/mol and $0.2$ kcal/mol for the HPS1 and HPS2 hydropathy\nscales. We use these best-fit parameters to investigate both the universal\naspects as well as the fine structures of the individual IDPs by introducing\nadditional characteristics.(i) First, we investigate the polymer specific\nscaling relations of the IDPs in comparison to the universal scaling relations\n[Bair et al., J. Chem. Phys. 158, 204902 (2023)] for the homopolymers and we\ndemonstrate that IDPs are broadly characterized with a Flory exponent of 0.56\nwith the conclusion that conformations of the IDPs interpolate between Gaussian\nand 3DSAW chains. (ii) Then we introduce Wilson charge index W that captures\nthe essential features of charge interactions and distribution in the sequence\nspace, and (iii) a skewness parameter S that captures the finer shape variation\nof the gyration radii distribution related to the charge asymmetry. Finally,\nour study of the variation of <$R_g$> as a function of salt concentration\nprovides another important metric to bring out finer characteristics of the\nIDPs which may carry relevant information for the origin of life.",
        "positive": "Electronic properties of bilayer sheets forming moir\u00e9 patterns: In this article, we report the electronic band structures of hexagonal\nbilayer systems, specifically, rotated graphene-graphene and boron\nnitride-boron nitride bilayers, by introducing an angle between the layers and\nforming new periodic structures, known as moir\\'e patterns. Using a\nsemi-empirical tight-binding approach with a parametrized hopping parameter\nbetween the layers, using one orbital per-site approximation, and taking into\naccount nearest-neighbor interactions only, we found he electronic dispersion\nrelations to be around K points in a low energy approximation. Our results show\nthat graphene bilayers exhibit zero band gap for all angles tested in this\nwork. In boron nitride bilayers, the results reveal a tunable bandgap that\nsatisfies the prediction of the bandgap found in one-dimensional diatomic\nsystems presented in the literature."
    },
    {
        "anchor": "Low-temperature and high-temperature approximations for\n  penetrable-sphere fluids. Comparison with Monte Carlo simulations and\n  integral equation theories: The two-body interaction in dilute solutions of polymer chains in good\nsolvents can be modeled by means of effective bounded potentials, the simplest\nof which being that of penetrable spheres (PSs). In this paper we construct two\nsimple analytical theories for the structural properties of PS fluids: a\nlow-temperature (LT) approximation, that can be seen as an extension to PSs of\nthe well-known solution of the Percus-Yevick (PY) equation for hard spheres,\nand a high-temperature (HT) approximation based on the exact asymptotic\nbehavior in the limit of infinite temperature. Monte Carlo simulations for a\nwide range of temperatures and densities are performed to assess the validity\nof both theories. It is found that, despite their simplicity, the HT and LT\napproximations exhibit a fair agreement with the simulation data within their\nrespective domains of applicability, so that they complement each other. A\ncomparison with numerical solutions of the PY and the hypernetted-chain\napproximations is also carried out, the latter showing a very good performance,\nexcept inside the core at low temperatures.",
        "positive": "Entropic electrokinetics: recirculation, particle separation and\n  negative mobility: We show that when particles are suspended in an electrolyte confined between\ncorrugated charged surfaces, electrokinetic flows lead to a new set of\nphenomena such as particle separation, mixing for low-Reynolds micro- and\nnano-metric devices and negative mobility. Our analysis shows that such\nphenomena arise, for incompressible fluids, due to the interplay between the\nelectrostatic double layer and the corrugated geometrical confinement and that\nthey are magnified when the width of the channel is comparable to the Debye\nlength. Our characterization allows us to understand the physical origin of\nsuch phenomena therefore shading light on their possible relevance in a wide\nvariety of situations, ranging from nano- and micro-fluidic devices to\nbiological systems."
    },
    {
        "anchor": "Modelling drug delivery from multiple emulsions: We present a mechanistic model of drug release from a multiple emulsion into\nan external surrounding fluid. We consider a single multi-layer droplet where\nthe drug kinetics are described by a pure diffusive process through different\nliquid shells. The multi-layer problem is described by a system of diffusion\nequations coupled via interlayer conditions imposing continuity of drug\nconcentration and flux. Mass resistance is imposed at the outer boundary\nthrough the application of a surfactant at the external surface of the droplet.\nThe two-dimensional problem is solved numerically by finite volume\ndiscretization. Concentration profiles and drug release curves are presented\nfor three typical round-shaped (circle, ellipse and bullet) droplets and the\ndependency of the solution on the mass transfer coefficient at the surface\nanalyzed. The main result shows a reduced release time for an increased\nelongation of the droplets.",
        "positive": "Condensation Under Controlled Cooling: A Simulation Study: The formation, growth, structure and cluster size distribution (CSD)\nproperties in a two-dimensional system of particles interacting with\nLennard-Jones (LJ) potential under controlled cooling condition have been\nstudied using Monte-Carlo (MC) method considering modified Metropolis algorithm\nto introduce realistic thermal motion of the particles. The system, initially\nat relatively higher temperature Ti, undergoes temperature reduction following\nexponential law with decay constant a to a lower temperature Tf and\nsubsequently reaches equilibrium. The equilibrium phase configuration depends\nstrongly on the number density c of particles and a. The root mean square\nparticle displacement in the final equilibrium phase shows maximum value for a\n= ac ~ 10-3 for all c. The CSD properties obtained at a = 10-3 shows a sharp\npeak in the lower cluster size region for low c. The peak shifts towards higher\ncluster size for lower a. The CSD fits well with a modified Gamma distribution\nfunction. All of the particles in the system form a single cluster when c is\nlarger than a critical value cc (~0.5). A compact well-defined ordered\nstructure is obtained for c > cc and a << ac."
    },
    {
        "anchor": "Scaling laws for slippage on superhydrophobic fractal surfaces: We study the slippage on hierarchical fractal superhydrophobic surfaces, and\nfind an unexpected rich behavior for hydrodynamic friction on these surfaces.\nWe develop a scaling law approach for the effective slip length, which is\nvalidated by numerical resolution of the hydrodynamic equations. Our results\ndemonstrate that slippage does strongly depend on the fractal dimension, and is\nfound to be always smaller on fractal surfaces as compared to surfaces with\nregular patterns. This shows that in contrast to naive expectations, the value\nof effective contact angle is not sufficient to infer the amount of slippage on\na fractal surface: depending on the underlying geometry of the roughness,\nstrongly superhydrophobic surfaces may in some cases be fully inefficient in\nterms of drag reduction. Finally, our scaling analysis can be directly extended\nto the study of heat transfer at fractal surfaces, in order to estimate the\nKapitsa surface resistance on patterned surfaces, as well as to the question of\ntrapping of diffusing particles by patchy hierarchical surfaces, in the context\nof chemoreception.",
        "positive": "Interdigitation between surface-anchored polymer chains and an elastomer\n  : consequences for adhesion promotion: We study the adhesion between a cross-linked elastomer and a flat solid\nsurface where polymer chains have been end-grafted. To understand the adhesive\nfeature of such a system, one has to study both the origin of the grafted layer\ninterdigitation with the network, and the end-grafted chains extraction out of\nthe elastomer when it comes unstuck from the solid surface. We shall tackle\nhere the first aspect for which we develop a partial interdigitation model that\nlets us analytically predict a critical surface grafting density $\\sigma^{*}\n\\simeq P^{{1/10}}N^{-{3/5}}$ beyond which the layer no longer interdigitates\nwith the elastomer. We then relate this result with recent adhesion\nmeasurements."
    },
    {
        "anchor": "Models for Metal Hydride Particle Shape, Packing, and Heat Transfer: A multiphysics modeling approach for heat conduction in metal hydride powders\nis presented, including particle shape distribution, size distribution,\ngranular packing structure, and effective thermal conductivity. A statistical\ngeometric model is presented that replicates features of particle size and\nshape distributions observed experimentally that result from cyclic hydride\ndecreptitation. The quasi-static dense packing of a sample set of these\nparticles is simulated via energy-based structural optimization methods. These\nparticles jam (i.e., solidify) at a density (solid volume fraction) of\n0.665+/-0.015 - higher than prior experimental estimates. Effective thermal\nconductivity of the jammed system is simulated and found to follow the behavior\npredicted by granular effective medium theory. Finally, a theory is presented\nthat links the properties of bi-porous cohesive powders to the present systems\nbased on recent experimental observations of jammed packings of fine powder.\nThis theory produces quantitative experimental agreement with metal hydride\npowders of various compositions.",
        "positive": "Nonequilibrium thermodynamics versus model grain growth: derivation and\n  some physical implications: Nonequilibrium thermodynamics formalism is proposed to derive the flux of\ngrainy (bubbles-containing) matter, emerging in a nucleation growth process.\nSome power and non-power limits, due to the applied potential as well as owing\nto basic correlations in such systems, have been discussed. Some encouragement\nfor such a discussion comes from the fact that the nucleation and growth\nprocesses studied, and their kinetics, are frequently reported in literature as\nself-similar (characteristic of algebraic correlations and laws) both in basic\nentity (grain; bubble) size as well as time scales."
    },
    {
        "anchor": "The influence of charged-induced variations in the local permittivity on\n  the static and dynamic properties of polyelectrolyte solutions: There is a large body of literature investigating the static and dynamic\nproperties of polyelectrolytes due both to their widespread application in\nindustrial processes and their ubiquitous presence in biology. Because of their\nhighly charged nature, polyelectrolytes tend to alter the local dielectric\npermittivity of the solution within a few nanometers of their backbone. This\neffect has, however, been almost entirely ignored in both simulations and\ntheoretical work. In this article we apply our recently developed electrostatic\nsolver based on Maxwell's equations to examine the effects of the permittivity\nreduction in the vicinity of the polyelectrolyte. We first verify our new\napproach by calculating and comparing ion distributions around a linear fixed\npolyelectrolyte and find both quantitative and qualitative changes in the ion\ndistribution. Further simulations with an applied electric field show that the\nreduction in the local dielectric constant increases the mobility of the chains\nby approximately ten percent. More importantly, variations in the local\ndielectric constant lead to qualitatively different behavior of the\nconductivity.",
        "positive": "A water film motor: We report on electrically-induced rotations in water films, which can\nfunction at many length scales. The device consists of a two-dimensional cell\nused for electrolysis of water films, as simple as an insulator frame with two\nelectrodes on the sides, to which an external in-plane electric field\nperpendicular to the mean electrolysis current density is applied. If either\nthe external field or the electrolysis current exceeds some threshold (while\nthe other one is not zero), the liquid film begins to rotate."
    },
    {
        "anchor": "Rheological properties of soft-glassy flows from hydro-kinetic\n  simulations: Based on numerical simulations of a lattice kinetic model for soft-glassy\nmaterials, we characterize the global rheology of a dense emulsion-like system,\nunder three representative load conditions: Couette flow, time-oscillating\nStrain and Kolmogorov flow. It is found that in all cases the rheology is\ndescribed by a Herschel-Bulkley (HB) relation, $\\sigma = {\\sigma}_{Y} + A\nS^{\\beta}$, with the yield stress ${\\sigma}_{Y}$ largely independent of the\nloading scenario. A proper rescaling of the HB parameters permits to describe\nheterogeneous flows with space-dependent stresses, based on the notion of\ncooperativity, as recently proposed to characterize the degree of non-locality\nof stress relaxation phenomena in soft-glassy materials.",
        "positive": "Static and Dynamical Phyllotaxis in a Magnetic Cactus: While the statics of many simple physical systems reproduce the striking\nnumber-theoretical patterns found in the phyllotaxis of living beings, their\ndynamics reveal unusual excitations: multiple classical rotons and a large\nfamily of interconverting topological solitons. As we introduce those, we also\ndemonstrate experimentally for the first time Levitov's celebrated model for\nphyllotaxis. Applications at different scales and in different areas of physics\nare proposed and discussed."
    },
    {
        "anchor": "Full alignment of colloidal objects by programmed forcing: By analysis and simulation we demonstrate two methods for achieving complete\norientational alignment of a set of identical, asymmetric colloidal objects\ndispersed randomly in a fluid. Sedimentation or electrophoresis in a constant\nfield can lead to partial alignment, in which the objects rotate about a common\nbody axis, but the phases of rotation for these objects are random. We show\nthat this phase disorder can be removed by two forms of programmed forcing.\nFirst, simply alternating the forcing between two directions reduces the\nstatistical entropy of the orientation arbitrarily. Second, addition of a small\nrotating component to the applied field in analogy to magnetic resonance can\nlead to phase locking of the objects' orientation. We identify conditions for\nalignment of a broad class of generic objects and discuss practical\nlimitations.",
        "positive": "Dynamics of viscoelastic snap-through: We study the dynamics of snap-through when viscoelastic effects are present.\nTo gain analytical insight we analyse a modified form of the Mises truss, a\nsingle-degree-of-freedom structure, which features an `inverted' shape that\nsnaps to a `natural' shape. Motivated by the anomalously slow snap-through\nshown by spherical elastic caps, we consider a thought experiment in which the\ntruss is first indented to an inverted state and allowed to relax while a\nspecified displacement is maintained; the constraint of an imposed displacement\nis then removed. Focussing on the dynamics for the limit in which the timescale\nof viscous relaxation is much larger than the characteristic elastic timescale,\nwe show that two types of snap-through are possible: the truss either\nimmediately snaps back over the elastic timescale or it displays\n`pseudo-bistability', in which it undergoes a slow creeping motion before\nrapidly accelerating. In particular, we demonstrate that accurately determining\nwhen pseudo-bistability occurs requires the consideration of inertial effects\nimmediately after the indentation force is removed. Our analysis also explains\nmany basic features of pseudo-bistability that have been observed previously in\nexperiments and numerical simulations; for example, we show that\npseudo-bistability occurs in a narrow parameter range at the bifurcation\nbetween bistability and monostability, so that the dynamics is naturally\nsusceptible to critical slowing down. We then study an analogous thought\nexperiment performed on a continuous arch, showing that the qualitative\nfeatures of the snap-through dynamics are well captured by the truss model. In\naddition, we analyse experimental and numerical data of viscoelastic\nsnap-through times reported in the literature. Combining these approaches\nsuggests that our conclusions may also extend to more complex viscoelastic\nstructures used in morphing applications."
    },
    {
        "anchor": "Pattern Formation in a Substrate--Contactor System with Two Interacting\n  Incompressible Elastic Films: The surface stability of two interacting (for example, by van der Waals\nforces) incompressible thin films, one bonded to a substrate and the other to a\ncontactor, is studied extending the work of Shenoy and Sharma, Physical Review\nLetters 18, 119--122 (2001). The analysis indicates that the wavelength of the\ninstability depends strongly on the shear moduli and thicknesses of the films\nbut not on the nature and magnitude of the interaction. When the films have\nequal shear moduli, the wavelength of the instability has an intermediate value\nbetween the wavelengths of the instabilities had each of the films been\ninteracting with rigid contactors. On the other hand, if the films have\ndifferent shear moduli but equal thicknesses, then the wavelength of the\ninstability is identical to that had the films been interacting with rigid\ncontactors. In the more general case when the two films have different shear\nmoduli and thicknesses, the nature of the critical wavelength is more complex.\nWhen ratio of the shear moduli of the contacting film to that of the film\nbonded to the substrate exceeds 5.32, the wavelength of the of the instability\njumps from the value close to that determined by the thickness of the film\nbonded to the substrate to that of the contacting film, as the thickness of the\ncontacting film is increased.",
        "positive": "Granular Avalanches in Fluids: Three regimes of granular avalanches in fluids are put in light depending on\nthe Stokes number St which prescribes the relative importance of grain inertia\nand fluid viscous effects, and on the grain/fluid density ratio r. In gas (r >>\n1 and St > 1, e.g., the dry case), the amplitude and time duration of\navalanches do not depend on any fluid effect. In liquids (r ~ 1), for\ndecreasing St, the amplitude decreases and the time duration increases,\nexploring an inertial regime and a viscous regime. These regimes are described\nby the analysis of the elementary motion of one grain."
    },
    {
        "anchor": "A texture tensor to quantify deformations: the example of\n  two-dimensional flowing foams: In a continuum description of materials, the stress tensor field $\\bar{%\n\\bar{\\sigma}}$ quantifies the internal forces the neighbouring regions exert on\na region of the material. The classical theory of elastic solids assumes that\n$\\bar{\\bar{\\sigma}}$ determines the strain, while hydrodynamics assumes that\n$\\bar{\\bar{\\sigma}}$ determines the strain rate. To extend both successful\ntheories to more general materials, which display both elastic and fluid\nproperties, we recently introduced a descriptor generalizing the classical\nstrain to include plastic deformations: the ``statistical strain'', based on\naverages on microscopic details (``A texture tensor to quantify deformations''\nM.Au., Y.J., J.A.G., F.G, companion paper, {\\em Granular Matter}, same issue).\nHere, we apply such a statistical analysis to a two-dimensional foam steadily\nflowing through a constriction, a problem beyond reach of both theories, and\nprove that the foam has the elastic properties of a (linear and isotropic)\ncontinuous medium.",
        "positive": "The dynamics of loop formation in a semiflexible polymer: The dynamics of loop formation by linear polymer chains has been a topic of\nseveral theoretical/experimental studies. Formation of loops and their opening\nare key processes in many important biological processes. Loop formation in\nflexible chains has been extensively studied by many groups. However, in the\nmore realistic case of semiflexible polymers, not much results are available.\nIn a recent study (K. P. Santo and K. L. Sebastian, Phys. Rev. E, \\textbf{73},\n031293 (2006)), we investigated opening dynamics of semiflexible loops in the\nshort chain limit and presented results for opening rates as a function of the\nlength of the chain. We presented an approximate model for a semiflexible\npolymer in the rod limit, based on a semiclassical expansion of the bending\nenergy of the chain. The model provided an easy way to describe the dynamics.\nIn this paper, using this model, we investigate the reverse process, i.e., the\nloop formation dynamics of a semiflexible polymer chain by describing the\nprocess as a diffusion-controlled reaction. We perform a detailed\nmultidimensional analysis of the problem and calculate closing times for a\nsemiflexible chain which leads to results that are physically expected. Such a\nmultidimensional analysis leading to these results does not seem to exist in\nthe literature so far."
    },
    {
        "anchor": "Statistical mechanics of granular media: An approach A la Boltzmann: We use an analogy with the statistical mechanics of gas to build the\nstatistical mechanics of granular media. The case of an isotropic disordered\npacking of equal spheres submitted to an isotropic stress is considered. We use\nthe assumption of a maximal disorder and the method of the Lagrange multipliers\nto demonstrate that the distribution of the force moduli decreases\nexponentially and obeys an exponential-decay statistics. This distribution\nresults from the above hypotheses and from the existence of a mean stress,\nwhich acts as a constraint. This distribution is confirmed by experiments and\nsimulations. We apply the same method to find the distribution of void defects\nof a granular assembly. It follows also an exponential-decay statistics.",
        "positive": "Constitutive equations for an electro-active polymer: Ionic electro-active polymers (E.A.P.) can be used as sensors or actuators.\nFor this purpose, a thin film of polyelectrolyte is saturated with a solvent\nand sandwiched between two platinum electrodes. The solvent causes a complete\ndissociation of the polymer and the release of small cations. The application\nof an electric field across the thickness results in the bending of the strip\nand vice versa. The material is modelled by a two-phase continuous medium. The\nsolid phase, constituted by the polymer backbone inlaid with anions, is\ndepicted as a deformable porous media. The liquid phase is composed of the free\ncations and the solvent (usually water). We used a coarse grain model. The\nconservation laws of this system have been established in a previous work. The\nentropy balance law and the thermodynamic relations are first written for each\nphase, then for the complete material using a statistical average technique and\nthe material derivative concept. One deduces the entropy production.\nIdentifying generalized forces and fluxes provides the constitutive equations\nof the whole system : the stress-strain relations which satisfy a Kelvin-Voigt\nmodel, generalized Fourier's and Darcy's laws and the Nernst-Planck equation."
    },
    {
        "anchor": "\"Water to the ropes\": a predictive model for the supercontraction stress\n  of spider silks: When humidified at different moisture conditions, restrained spider silk\nfibers can exhibit a very high supercontraction phenomenon. The hydration water\nmolecules induce a Hydrogen-bonds disruption process that, due to entropic\neffects, decreases the natural -- zero force -- end-to-end chains length. By\nconsidering a bundle of macromolecules, we describe supercontraction as a\npossible actuation system and determine the maximum actuation force depending\non the silk properties at the molecular scale and on the constraining system\nrepresenting other silk threads or the actuated device. The comparison with\nexperimental results of Argiope trifasciata silk fibers show the effectiveness\nof the proposed model in quantitatively predicting the experimental actuation\nproperties. The considered historical case study of obelisk rescue in Saint\nPeter's Square (Rome) through ropes hydration is discussed evidencing the\noptimal performances of this natural material adopted as moisture powered\nactuator: we obtain a work density of 2.19 kJ/m3 making spider silk the most\nperformant hydration driven active material. Moreover we obtain a power density\nof the order of 730 W/kg about three times the most performant carbon nanotube\nactuators making such material very competitive as compared with all types of\nactuator. The analytic description of the macroscopic actuation parameters from\nmicroscale properties shows the possibility of adopting our approach also in\nthe field of bioinspired artificial silks design, possibly considering also\nimportant non-linear effects in the actuated system.",
        "positive": "Inertial self-propelled particles in anisotropic environments: Self-propelled particles in anisotropic environments can exhibit a motility\nthat depends on their orientation. This dependence is relevant for a plethora\nof living organisms but difficult to study in controlled environments. Here, we\npresent a macroscopic system of self-propelled vibrated granular particles on a\nstriated substrate that displays orientation-dependent motility. An extension\nof the active Brownian motion model involving orientation-dependent motility\nand inertial effects reproduces and explains our experimental observations. The\nmodel can be applied to general $n$-fold symmetric anisotropy and can be\nhelpful for predictive optimization of the dynamics of active matter in complex\nenvironments."
    },
    {
        "anchor": "Rheology of Active Filament Solutions: We study the viscoelasticity of an active solution of polar biofilaments and\nmotor proteins. Using a molecular model, we derive the constitutive equations\nfor the stress tensor in the isotropic phase and in phases with liquid\ncrystalline order. The stress relaxation in the various phases is discussed.\nContractile activity is responsible for a spectacular difference in the\nviscoelastic properties on opposite sides of the order-disorder transition.",
        "positive": "Fourth order nematic elasticity and modulated nematic phases: a poor\n  man's approach: We propose an extension of Frank-Oseen's elastic energy for bulk nematic\nliquid crystals which is based on the hypothesis that the fundamental\ndeformations allowed in nematic liquid crystals are splay, twist and bend. The\nextended elastic energy is a fourth order form in the fundamental deformations.\nThe existence of bulk spontaneous modulated or deformed nematic liquid crystal\nground states is investigated. The analysis is limited to bulk nematic liquid\ncrystals in the absence of limiting surfaces and/or external fields. The non\ndeformed ground state is stable only when Frank-Oseen's elastic constants are\npositive. In case where at least one of them is negative, the ground state\nbecomes deformed. The analysis of the stability of the deformed states in the\nspace of the elastic parameters allows to characterize different types of\ndeformed nematic phases. Some of them are new nematic phases, for instance a\ntwist -- splay nematic phase is predicted. Inequalities between second order\nelastic constants which govern the stability of the twist--bend and splay--bend\nstate are obtained."
    },
    {
        "anchor": "Nonadditive drag of tandem rods drafting in granular sediments: We examine the drag experienced by a pair of vertical rods moving in tandem\nthrough a granular bed immersed in a fluid as a function of their separation\ndistance and speed. As in Newtonian fluids, the net drag experienced by the\nrods initially increases with distance from the value for a single rod before\nplateauing to twice the value. However, the drag acting on the two rods is\nremarkably different, with the leading rod experiencing roughly similar drag\ncompared to a solitary rod, while the following rod experiences far less drag.\nThe anomalous relationship of drag and the distance between the leading and\nfollowing body is observed in both dry granular beds and while immersed in\nviscous Newtonian fluids across the quasi-static and the rate-dependent\nregimes. Through refractive index matching, we visualize the sediment flow past\nthe two rods and show that a stagnant region develops in their reference frame\nbetween the rods for small separations. Thus, the following rod is increasingly\nshielded from the granular flow with decreasing separation distance, leading to\na lower net drag. Care should be exercised in applying resistive force theory\nto multi-component objects moving in granular sediments based on our result\nthat drag is not additive at short separation distances.",
        "positive": "Role of water in Protein Aggregation and Amyloid Polymorphism: A variety of neurodegenerative diseases are associated with the formation of\namyloid plaques. Our incomplete understanding of this process underscores the\nneed to decipher the principles governing protein aggregation. Most\nexperimental and simulation studies have been interpreted largely from the\nperspective of proteins: the role of solvent has been relatively overlooked.\n  In this Account, we provide a perspective on how interactions with water\naffect folding landscapes of A$\\beta$ monomers, A$\\beta_{16-22}$ oligomer\nformation, and protofilament formation in a Sup35 peptide. Simulations show\nthat the formation of aggregation-prone structures (N$^*$) similar to the\nstructure in the fibril requires overcoming high desolvation barrier. The\nmechanism of protofilament formation in a polar Sup35 peptide fragment\nillustrates that water dramatically slows down self-assembly. Release of water\ntrapped in the pores as water wires creates protofilament with a dry interface.\nSimilarly, one of the main driving force for addition of a solvated monomer to\na preformed fibril is the entropy gain of released water.\n  We conclude by postulating that two-step model for protein crystallization\nmust also hold for higher order amyloid structure formation starting from\nN$^*$. Multiple N$^*$ structures with varying water content results in a number\nof distinct water-laden polymorphic structures. In predominantly hydrophobic\nsequences, water accelerates fibril formation. In contrast, water-stabilized\nmetastable intermediates dramatically slow down fibril growth rates in\nhydrophilic sequences."
    },
    {
        "anchor": "The effect of anchoring on nematic flow in channels: Understanding the flow of liquid crystals in microfluidic environments plays\nan important role in many fields, including device design and microbiology. We\nperform hybrid lattice-Boltzmann simulations of a nematic liquid crystal\nflowing under an applied pressure gradient in two-dimensional channels with\nvarious anchoring boundary conditions at the substrate walls. We investigate\nthe relation between flow rate and pressure gradient and the corresponding\nprofile of the nematic director, and find significant departures from the\nlinear Poiseuille relation. We also identify a morphological transition in the\ndirector profile and explain this in terms of an instability in the dynamical\nequations. We examine the qualitative and quantitative effects of changing the\ntype and strength of the anchoring. Understanding such effects may provide a\nuseful means of quantifying the anchoring of a substrate by measuring its flow\nproperties.",
        "positive": "PolyHoop: Soft particle and tissue dynamics with topological transitions: We present PolyHoop, a lightweight standalone C++ implementation of a\nmechanical model to simulate the dynamics of soft particles and cellular\ntissues in two dimensions. With only few geometrical and physical parameters,\nPolyHoop is capable of simulating a wide range of particulate soft matter\nsystems: from biological cells and tissues to vesicles, bubbles, foams,\nemulsions, and other amorphous materials. The soft particles or cells are\nrepresented by continuously remodeling, non-convex, high-resolution polygons\nthat can undergo growth, division, fusion, aggregation, and separation. With\nPolyHoop, a tissue or foam consisting of a million cells with high spatial\nresolution can be simulated on conventional laptop computers."
    },
    {
        "anchor": "Geometric origin of mechanical properties of granular materials: Some remarkable generic properties, related to isostaticity and potential\nenergy minimization, of equilibrium configurations of assemblies of rigid,\nfrictionless grains are studied. Isostaticity -the uniqueness of the forces,\nonce the list of contacts is known- is established in a quite general context,\nand the important distinction between isostatic problems under given external\nloads and isostatic (rigid) structures is presented. Complete rigidity is only\nguaranteed, on stability grounds, in the case of spherical cohesionless grains.\nOtherwise, the network of contacts might deform elastically in response to load\nincrements, even though grains are rigid. This sets an uuper bound on the\ncontact coordination number. The approximation of small displacements (ASD)\nallows to draw analogies with other model systems studied in statistical\nmechanics, such as minimum paths on a lattice. It also entails the uniqueness\nof the equilibrium state (the list of contacts itself is geometrically\ndetermined) for cohesionless grains, and thus the absence of plastic\ndissipation. Plasticity and hysteresis are due to the lack of such uniqueness\nand may stem, apart from intergranular friction, from small, but finite,\nrearrangements, in which the system jumps between two distinct potential energy\nminima, or from bounded tensile contact forces. The response to load increments\nis discussed. On the basis of past numerical studies, we argue that, if the ASD\nis valid, the macroscopic displacement field is the solution to an elliptic\nboundary value problem (akin to the Stokes problem).",
        "positive": "Velocity difference statistics in turbulence: We unify two approaches that have been taken to explain the non-Gaussian\nprobability distribution functions (PDFs) obtained in measurements of\nlongitudinal velocity differences in turbulence, and we apply our approach to\nCouette-Taylor turbulence data. The first approach we consider was developed by\nCastaing and coworkers, who obtained the non-Gaussian velocity difference PDF\nfrom a superposition of Gaussian distributions for subsystems that have a\nparticular energy dissipation rate at a fixed length scale [Castaing et al.,\n{\\it Physica D} {\\bf 46}, 177 (1990)]. Another approach was proposed by Beck\nand Cohen, who showed that the observed PDFs can be obtained from a\nsuperposition of Gaussian velocity difference PDFs in subsystems conditioned on\nthe value of an intensive variable (inverse ``effective temperature'') in each\nsubsystem [Beck and Cohen, {\\it Physica A} {\\bf 322}, 267 (2003)]. The\nintensive variable was defined for subsystems assuming local thermodynamic\nequilibrium, but no method was proposed for determining the size of a\nsubsystem. We show that the Castaing and Beck-Cohen methods are related, and we\npresent a way to determine subsystem size in the Beck-Cohen method. The\napplication of our approach to Couette-Taylor turbulence (Reynolds number\n$540~000$) yields a log-normal distribution of the intensive parameter, and the\nresultant velocity difference PDF agrees well the observed non-Gaussian\nvelocity difference PDFs."
    },
    {
        "anchor": "Ordering in dense fiber bundles, the phyllotactic solution and its\n  application to collagen fibrils: The shape of the cross section of a dense fiber bundle is related to the\nsymmetry of its molecular packing. However, this statement might be belied by\ntype I collagen fibrils which have a rounded section of high symmetry while\nstructural studies suggest that their molecules are assembled with a long range\nlateral order of lower symmetry. We examine how phyllotaxis, which is a non\nconventional crystallographic solution to packing efficiency in situations of\nhigh radial symmetry, can establish a link between those two apparently\nconflicting points. The lateral order imposed by the algorithm of phyllotaxis,\nwhich implies an enlargement of the notion of long range lateral order beyond\nthat used for classical crystals, provides a basis for a new analysis of the\nexperimental data.",
        "positive": "The role of boson-fermion correlations in the resonance theory of\n  superfluids: Correlations between a composite boson and a fermion pair are considered in\nthe context of the crossover theory of fermionic to bosonic superfluidity. It\nis shown that such correlations are the minimal ingredients needed in a\nmany-body theory to generate the right boson-boson scattering length in the\nBose-Einstein limit of the crossover."
    },
    {
        "anchor": "Dynamics of relaxation to a stationary state for interacting molecular\n  motors: Motor proteins are active enzymatic molecules that drive a variety of\nbiological processes, including transfer of genetic information, cellular\ntransport, cell motility and muscles contraction. It is known that these\nbiological molecular motors usually perform their cellular tasks by acting\ncollectively, and there are interactions between individual motors that specify\nthe overall collective behavior. One of the fundamental issues related to the\ncollective dynamics of motor proteins is the question if they function at\nstationary-state conditions. To investigate this problem, we analyze a\nrelaxation to the stationary state for the system of interacting molecular\nmotors. Our approach utilizes a recently developed theoretical framework, which\nviews the collective dynamics of motor proteins as a totally asymmetric simple\nexclusion process of interacting particles, where interactions are taken into\naccount via a thermodynamically consistent approach. The dynamics of relaxation\nto the stationary state is analyzed using a domain-wall method that relies on a\nmean-field description, which takes into account some correlations. It is found\nthat the system quickly relaxes for repulsive interactions, while attractive\ninteractions always slow down reaching the stationary state. It is also\npredicted that for some range of parameters the fastest relaxation might be\nachieved for a weak repulsive interaction. Our theoretical predictions are\ntested with Monte Carlo computer simulations. The implications of our findings\nfor biological systems are briefly discussed.",
        "positive": "Shear induced breakup of droplets in a colloidal dispersion: We present numerical results for the breakup of a pair of colloidal particles\nenveloped by a droplet under shear flow. The smoothed profile method is used to\naccurately account for the hydrodynamic interactions between particles due to\nthe host fluid. We observe that the critical capillary number, $Ca_{\\rm B}$, at\nwhich droplets breakup depends on a velocity ratio, $E$, defined as the ratio\nof the boundary shift velocity (that restores the droplet shape to a sphere) to\nthe diffusive flux velocity in units of the particle radius $a$. For $E < 10$,\n$Ca_{B}$ is independent of $E$, as is consistent with the regime studied by\nTaylor. When $E > 10$, $Ca_{B}$ behaves as $Ca_{\\rm B} = 2E^{-1}$, which\nconfirms Karam and Bellinger's hypothesis. As a consequence, droplet break up\nwill occur when the time scale of droplet deformation $\\dot{\\gamma}^{-1}$ is\nsmaller than the diffusive time scale $t_{D} \\equiv a^{2}/L\\tau$ in units of\n$a$, where $L$ is the diffusion constant and $\\tau$ is the 2nd order\ncoefficient of the Ginzburg-Landau type free energy of the binary mixture. We\nemphasize that the breakup of droplet dispersed particles is not only governed\nby a balance of forces. We find that velocity competition is one of the\nimportant contributing factor."
    },
    {
        "anchor": "Microscopic Origins of the Swim Pressure and the Anomalous Surface\n  Tension of Active Matter: The unique pressure exerted by active particles -- the \"swim\" pressure -- has\nproven to be a useful quantity in explaining many of the seemingly confounding\nbehaviors of active particles. However, its use has also resulted in some\npuzzling findings including an \\textit{extremely negative} surface tension\nbetween phase separated active particles. Here, we demonstrate that this\ncontradiction stems from the fact that the swim pressure \\textit{is not a true\npressure}. At a boundary or interface, the reduction in particle swimming\ngenerates a net active force density -- an entirely \\textit{self-generated body\nforce}. The pressure at the boundary, which was previously identified as the\nswim pressure, is in fact an elevated (relative to the bulk) value of the\n\\textit{traditional particle pressure} that is generated by this interfacial\nforce density. Recognizing this unique mechanism for stress generation allows\nus to define a much more physically plausible surface tension. We clarify the\nutility of the swim pressure as an \"equivalent pressure\" (analogous to those\ndefined from electrostatic and gravitational body forces) and the conditions in\nwhich this concept can be appropriately applied.",
        "positive": "Flashing a look at the stability of the uniform ferroelectric nematic\n  phase: Recent discovery of the ferroelectric nematic phase N_F resurrects a question\nabout stability of the uniform N_F state with respect to the formation of\neither standard for solid ferroelectrics domain structure, or often occurring\nin liquid crystals space modulation of the polarization vector P (and naturally\ncoupled to P nematic director. In this work within Landau mean-field theory we\ninvestigate the linear stability of the minimal model admitting the\nconventional paraelectric nematic N and N_F phases. Our minimal model, (besides\nthe standard terms of the expansion over P and director gradients) includes,\nalso standard for liquid crystals, director flexoelectric coupling term f and\noften overlooked in the literature (although similar by its symmetry to the\ndirector flexoelectric coupling) the flexo-dipolar coupling. We find that in\nthe easy-plane anisotropy case the uniform N_F state loses its stability with\nrespect to one-dimensional or two-dimensional modulation. For non-zero f the 2D\nmodulation threshold is always higher than its 1D counterpart. No any\ninstability at all if one neglects the dipole-flexoelectric coupling. In the\neasy-axis case the both instability thresholds are the same, and the\ninstability can occur even without flexo-dipolr coupling. We speculate that the\nphases with 1D or 2D modulations can be identified with discussed in the\nliterature [see M.P.Rosseto, J.V.Selinger, Physical Review E, volume 101, page\n052707 (2020)] single splay or double splay nematics."
    },
    {
        "anchor": "Self assembling of Poly(3-hexylthiophene) (P3HT): We study the assembling of P3HT chains in vacuo by means of a combination of\nfirst principles density functional theory and model potential molecular\ndynamics. We find that, in the absence of any external constraints, the pi-pi\ninterchain interaction between thiophenes is the major driving force for the\nassembling. Single chains stack in a staggered geometry giving rise to the\nformation of two-dimensional hydrophobic foils. These, in turn, assemble into a\nzigzag bulk polymer structure in agreement with experimental findings. Finally,\nin the presence of some external constraint (like e.g. a substrate), when the\nalignment of single chains is favored instead of the stacking, a different bulk\nstructure is possible where thiophene rings are aligned.",
        "positive": "A unification of finite deformation $J_2$ Von-Mises plasticity and\n  quantitative dislocation mechanics: We present a framework which unifies classical phenomenological $J_2$ and\ncrystal plasticity theories with quantitative dislocation mechanics. The theory\nallows the computation of stress fields of arbitrary dislocation distributions\nand, coupled with minimally modified classical ($J_2$ and crystal plasticity)\nmodels for the plastic strain rate of statistical dislocations, results in a\nversatile model of finite deformation mesoscale plasticity. We demonstrate some\ncapabilities of the framework by solving two outstanding challenge problems in\nmesoscale plasticity: 1) recover the experimentally observed power-law scaling\nof stress-strain behavior in constrained simple shear of thin metallic films\ninferred from micropillar experiments which all strain gradient plasticity\nmodels overestimate and fail to predict; 2) predict the finite deformation\nstress and energy density fields of a sequence of dislocation distributions\nrepresenting a progressively dense dislocation wall in a finite body, as might\narise in the process of polygonization when viewed macroscopically, with one\nconsequence being the demonstration of the inapplicability of current\nmathematical results based on $\\mathrm{\\Gamma}$-convergence for this physically\nrelevant situation. Our calculations in this case expose a possible `phase\ntransition' - like behavior for further theoretical study. We also provide a\nquantitative solution to the fundamental question of the volume change induced\nby dislocations in a finite deformation theory, as well as show the massive\nnon-uniqueness in the solution for the (inverse) deformation map of a body\ninherent in a model of finite strain dislocation mechanics, when approached as\na problem in classical finite elasticity."
    },
    {
        "anchor": "Linear and Nonlinear Viscoelasticity of Concentrated Thermoresponsive\n  Microgel Suspensions: This is an integrated experimental and theoretical study of the dynamics and\nrheology of self-crosslinked, slightly charged, temperature responsive soft\nPoly(N-isopropylacrylamide) (pNIPAM) microgels over a wide range of\nconcentration and temperature spanning the sharp change in particle size and\nintermolecular interactions across the lower critical solution temperature\n(LCST). Dramatic, non-monotonic changes in viscoelasticity are observed with\ntemperature, with distinctive concentration dependences in the dense fluid,\nglassy, and soft-jammed states. Motivated by our experimental observations, we\nformulate a minimalistic model for the size dependence of a single microgel\nparticle and the change of interparticle interaction from purely repulsive to\nattractive upon heating. Using microscopic equilibrium and time-dependent\nstatistical mechanical theories, theoretical predictions are quantitatively\ncompared with experimental measurements of the shear modulus. Good agreement is\nfound for the nonmonotonic temperature behavior that originates as a\nconsequence of the competition between reduced microgel packing fraction and\nincreasing interpar-ticle attractions. Testable predictions are made for\nnonlinear rheological properties such as the yield stress and strain. To the\nbest of our knowledge, this is the first attempt to quantitatively understand\nin a unified manner the viscoelasticity of dense, temperature-responsive\nmicrogel suspensions spanning a wide range of temperatures and concentrations.",
        "positive": "Universal deformations of ideal liquid crystal elastomers: Liquid crystal elastomers are rubber-like solids with liquid crystalline\nmesogens (stiff, rod-like molecules) incorporated either into the main chain or\nas a side chain of the polymer. These solids display a range of unusual\nthermo-mechanical properties as a result of the coupling between the entropic\nelasticity of rubber and the orientational phase transitions of liquid\ncrystals. One of these intriguing properties is the soft behavior, where it is\nable to undergo significant deformations with almost no stress. While the\nphenomenon is well-known, it has largely been examined in the context of\nhomogenous deformations. This paper investigates soft behavior in complex\ninhomogeneous deformations. We model these materials as hyperelastic,\nisotropic, incompressible solids and exploit the seminal work of Ericksen, who\nestablished the existence of non-trivial universal deformations, those that\nsatisfy the equations of equilibrium in every hyperelastic, isotropic,\nincompressible solid. We study the inflation of spherical and cylindrical\nballoons, cavitation and bending."
    },
    {
        "anchor": "Profile driven interfaces in 1 + 1 dimensions : periodic steady states,\n  dynamical melting and detachment: We study the steady state structure and dynamics of a 2-d Ising interface\nplaced in an inhomogeneous external field with a sigmoidal profile which moves\nwith velocity $v_{e}$. In the strong coupling limit the problem maps onto an\nassymmetric exclusion process involving motion of particles in 1-d with\nposition dependent right and left jump probabilities. For small $v_{e}$, the\ninterface is stuck to the field profile. As $v_{e}$ increases the profile\ndetaches from the interface. At the transition point(and beyond), the\ninterfacial structure and dynamics is characterized by KPZ exponents. For small\n$v_{e}$, on the other hand, the interface is macroscopically smooth with a\nvanishing roughness exponent $\\alpha$. The interfacial structure is periodic\nwith a periodicity which depends on the orientation of the interface. For a\nfixed orientation this periodic structure ``melts'' as $v_e$ is increased. We\ndetermine the dynamical ``phase - diagram'' of this system in the $v_e$ -\norientation plane.",
        "positive": "Thermodynamic properties of short-range attractive Yukawa fluid:\n  Simulation and theory: Coexistence properties of the hard-core attractive Yukawa potential with\ninverse-range parameter kappa=9, 10, 12 and 15 are calculated by applying\ncanonical Monte Carlo simulation. As previously shown for longer ranges, we\nshow that also for the ranges considered here the coexistence curves scaled by\nthe critical density and temperature obey the law of corresponding states, and\nthat a linear relationship between the critical density and the reciprocal of\nthe critical temperature holds. The simulation results are compared with the\npredictions of the self-consistent Ornstein-Zernike approximation, and a good\nagreement is found for both the critical points and the coexistence curves,\nalthough some slight discrepancies are present."
    },
    {
        "anchor": "Transport coefficients in composites: The Maxwell approach from electrostatics is applied for calculation of\ntransport coefficients in composites. The viscosity of a dilute emulsion is\nobtained as a function of the volume fraction of dispersed phase. The derived\nnew formula is asymptotically correct and more general than the linear\nrelationships usually used. The method is applied also for description of the\ninfluence of fluctuations on the transport coefficients.",
        "positive": "Solubility of ionic surfactants below their Krafft point in mixed\n  micellar solutions: Phase diagrams for methyl ester sulfonates and nonionic\n  cosurfactants: Many ionic surfactants with wide applications in personal-care and house-hold\ndetergency show limited water solubility at lower temperatures (Krafft point).\nThis drawback can be overcome by using mixed solutions, where the ionic\nsurfactant is incorporated in mixed micelles with another surfactant, which is\nsoluble at lower temperatures. The solubility and electrolytic conductivity for\na binary surfactant mixture of anionic methyl ester sulfonates (MES) with\nnonionic alkyl polyglucoside and alkyl polyoxyethylene ether at 5 deg C during\nlong-term storage were measured. Phase diagrams were established; a general\ntheoretical model for their explanation was developed and checked\nexperimentally. The binary and ternary phase diagrams for studied surfactant\nmixtures include phase domains: mixed micelles; micelles and crystallites;\ncrystallites, and molecular solution. The proposed general methodology, which\nutilizes the equations of molecular thermodynamics at minimum number of\nexperimental measurements, is convenient for construction of such phase\ndiagrams. The results could increase the range of applicability of\nMES-surfactants with relatively high Krafft temperature, but with various\nuseful properties such as excellent biodegradability and skin compatibility;\nstability in hard water; good wetting and cleaning performance."
    },
    {
        "anchor": "Phase transitions in simple and not so simple binary fluids: Compared to pure fluids, binary mixtures display a very diverse phase\nbehavior, which depends sensitively on the parameters of the microscopic\npotential. Here we investigate the phase diagrams of simple model mixtures by\nuse of a microscopic implementation of the renormalization group technique.\nFirst, we consider a symmetric mixture with attractive interactions, possibly\nrelevant for describing fluids of molecules with internal degrees of freedom.\nDespite the simplicity of the model, slightly tuning the strength of the\ninteractions between unlike species drastically changes the topology of the\nphase boundary, forcing or inhibiting demixing, and brings about several\ninteresting features such as double critical points, tricritical points, and\ncoexistence domains enclosing `islands' of homogeneous, mixed fluid.\nHomogeneous phase separation in mixtures can be driven also by purely repulsive\ninteractions. As an example, we consider a model of soft particles which has\nbeen adopted to describe binary polymer solutions. This is shown to display\ndemixing (fluid-fluid) transition at sufficiently high density. The nature and\nthe physical properties of the corresponding phase transition are investigated.",
        "positive": "Brillouin Scattering Study of Propylene Carbonate: An Evaluation of\n  Phenomenological and Mode Coupling Analyses: Brillouin scattering spectra of the molecular glassformer propylene carbonate\n(PC) in the temperature range 140 K to 350 K were analyzed using both the\nphenomenological Cole-Davidson memory function and a hybrid memory function\nconsisting of the Cole-Davidson function plus a power-law term representing the\ncritical decay part of the fast beta relaxation. The spectra were also analyzed\nusing the extended two-correlator schematic MCT model recently employed by\nGotze and Voigtmann to analyze depolarized light backscattering,dielectric, and\nneutron-scattering spectra of PC [W.Gotze and Th. Voigtman, Phys. Rev. E61,\n4133 (2000). We assess the ability of the phenomenological and MCT fits, each\nwith three free fitting parameters, to simultaneously describe the spectra and\ngive reasonable values for the alpha-relaxation time tau-alpha"
    },
    {
        "anchor": "Pore-scale simulations of drainage in granular materials: finite size\n  effects and the representative elementary volume: A pore-scale model is introduced for two-phase flow in dense packings of\npolydisperse spheres. The model is developed as a component of a more general\nhydromechanical coupling framework based on the discrete element method, which\nwill be elaborated in future papers. Here the emphasis is on the generation of\na network of pores mapping the void space between spherical grains, and the\ndefinition of local criteria governing the primary drainage process. The pore\nspace is decomposed by Regular Triangulation, from which a set of pores\nconnected by throats are identified. A local entry capillary pressure is\nevaluated for each throat, based on the balance of capillary pressure and\nsurface tension at equilibrium. The model reflects the possible entrapment of\ndisconnected patches of the receding wetting phase. It is validated by a\ncomparison with drainage experiments. A series of simulations are reported to\nillustrate size and boundary effects, key questions when studying small samples\nmade of spherical particles be it in simulations or experiments. Repeated tests\non samples of different sizes give evolution of water content which are not\nonly scattered but also strongly biased for small sample sizes. More than\n20,000 spheres are needed to reduce the bias on saturation below 0.02.\nAdditional statistics are generated by subsampling a large sample of 64,000\nspheres. They suggest that the minimal sampling volume for evaluating\nsaturation is one hundred times greater that the sampling volume needed for\nmeasuring porosity with the same accuracy. This requirement in terms of sample\nsize induces a need for efficient computer codes. The method described herein\nhas a low algorithmic complexity in order to satisfy this requirement. It will\nbe well suited to further developments toward coupled flow-deformation problems\nin which evolution of the microstructure require frequent updates of the pore\nnetwork.",
        "positive": "Activity-assisted barrier-crossing of self-propelled colloids over\n  parallel microgrooves: We report a systematic study of the dynamics of self-propelled particles\n(SPPs) over a one-dimensional periodic potential landscape, which is fabricated\non a microgroove-patterned polydimethylsiloxane (PDMS) substrate. From the\nmeasured non-equilibrium probability density function of the SPPs, we find that\nthe escape dynamics of the slow-rotating SPPs across the potential landscape\ncan be described by an effective potential, once the self-propulsion force is\nincluded into the potential under the fixed angle approximation. This work\ndemonstrates that the parallel microgrooves provide a versatile platform for a\nquantitative understanding of the interplay among the self-propulsion force,\nspatial confinement by the potential landscape, and thermal noise, as well as\nits effects on activity-assisted escape dynamics and transport of the SPPs."
    },
    {
        "anchor": "Statistical Mechanics of Developable Ribbons: We investigate the statistical mechanics of long developable ribbons of\nfinite width and very small thickness. The constraint of isometric deformations\nin these ribbon-like structures that follows from the geometric separation of\nscales introduces a coupling between bending and torsional degrees of freedom.\nUsing analytical techniques and Monte Carlo simulations, we find that the\ntangent-tangent correlation functions always exhibits an oscillatory decay at\nany finite temperature implying the existence of an underlying helical\nstructure even in absence of a preferential zero-temperature twist. In addition\nthe persistence length is found to be over three times larger than that of a\nwormlike chain having the same bending rigidity. Our results are applicable to\nmany ribbon-like objects in polymer physics and nanoscience that are not\ndescribed by the classical worm-like chain model.",
        "positive": "Clogging and Jamming Transitions in Periodic Obstacle Arrays: We numerically examine clogging transitions for bidisperse disks flowing\nthrough a two dimensional periodic obstacle array. We show that clogging is a\nprobabilistic event that occurs through a transition from a homogeneous flowing\nstate to a heterogeneous or phase separated jammed state where the disks form\ndense connected clusters. The probability for clogging to occur during a fixed\ntime increases with increasing particle packing and obstacle number. For\ndriving at different angles with respect to the symmetry direction of the\nobstacle array, we show that certain directions have a higher clogging\nsusceptibility. It is also possible to have a size-specific clogging transition\nin which one disk size becomes completely immobile while the other disk size\ncontinues to flow."
    },
    {
        "anchor": "Active Dynamics of Linear Chains and Rings in Porous Media: To understand the dynamical and conformational properties of deformable\nactive agents in porous media, we computationally investigate the dynamics of\nlinear chains and rings made of active Brownian monomers. In porous media,\nflexible linear chains and rings always migrate smoothly and undergo\nactivity-induced swelling. However, semiflexible linear chains though navigate\nsmoothly, shrink at lower activities, followed by swelling at higher\nactivities, while semiflexible rings exhibit a contrasting behavior.\nSemiflexible rings shrink, get trapped at lower activities, and escape at\nhigher activities. This demonstrates how activity and topology interplay and\ncontrol the structure and dynamics of linear chains and rings in porous media.\nWe envision that our study will shed light on understanding the mode of\ntransport of shape-changing active agents in porous media.",
        "positive": "Statistical properties of a tangentially driven active filament: Active polymers play a central role in many biological systems, from\nbacterial flagella to cellular cytoskeletons. Minimal models of semiflexible\nactive filaments have been used to study a variety of interesting phenomena in\nactive systems, such as defect dynamics in active nematics, clustering and\nlaning in motility assays, and conformational properties of chromatin in\neukaryotic cells. In this paper, we map a semiflexible polymer to an exactly\nsolvable active Rouse chain, which enables us to analytically compute\nconfigurational and dynamical properties of active polymers with arbitrary\nrigidity."
    },
    {
        "anchor": "Completely monotone solutions of the mode-coupling theory for mixtures: We establish that a mode-coupling approximation for the dynamics of\nmulti-component systems obeying Smoluchowski dynamics preserves a subtle yet\nfundamental property: the matrices of partial density correlation functions are\ncompletely monotone, i.e. they can exactly be written as superpositions of\ndecaying exponentials only. This statement holds, no matter what further\napproximations are needed to calculate the theory's coupling parameters. The\nlong-time limit of these functions fulfills a maximum property, and an\niteration scheme for its numerical determination is given. We also show the\nexistence of a unique solution to the equations of motion for which power\nseries both for short times and small frequencies exist, the latter except at\nspecial points where ergodic-to-nonergodic transitions occur. These transitions\nare bifurcations that are proven to be of the cuspoid family.",
        "positive": "Probabilistic approach to the length-scale dependence of the effect of\n  water hydrogen bonding on hydrophobic hydration: We present a probabilistic approach to water-water hydrogen bonding that\nallows one to obtain an analytic expression for the number of bonds per water\nmolecule as a function of both its distance to a hydrophobic particle and\nhydrophobe radius. This approach can be used in the density functional theory\n(DFT) and computer simulations to examine particle size effects on the\nhydration of particles and on their solvent-mediated interaction. For example,\nit allows one to explicitly identify a water hydrogen bond contribution to the\nexternal potential whereto a water molecule is subjected near a hydrophobe. The\nDFT implementation of the model predicts the hydration free energy per unit\narea of a spherical hydrophobe to be sharply sensitive to the hydropobe radius\nfor small radii and weakly sensitive thereto for large ones; this corroborates\nthe vision of the hydration of small and large length-scale particles as\noccurring via different mechanisms. On the other hand, the model predicts that\nthe hydration of even apolar particles of small enough radii may become\nthermodynamically favorable owing to the interplay of the energies of pairwise\n(dispersion) water-water and water-hydrophobe interactions. This sheds light on\nprevious counterintuitive observations (both theoretical and simulational) that\ntwo inert gas molecules would prefer to form a solvent-separated pair rather\nthan a contact one."
    },
    {
        "anchor": "Anomalous transport of magnetic colloids in a liquid crystal-magnetic\n  colloid mixture: We report an extensive molecular dynamics study on the translational dynamics\nof a hybrid system composed of dipolar soft spheres (DSS), representing\nferromagnetic particles, suspended in a liquid crystal (LC) matrix. We observe\nthat the LC matrix strongly modifies the dynamics of the DSS. In the isotropic\nregime, the DSS show a crossover from subdiffusive to normal diffusive behavior\nat long times, with an increase of the subdiffusive regime as the dipolar\ncoupling strength is increased. In the nematic regime, the LC matrix, due to\ncollective reorientation of LC particles, imposes a cylindrical confinement on\nthe DSS chains. This leads to a diffusive dynamics of DSS along the nematic\ndirector and a subdiffusive dynamics (with an exponent $\\sim 0.5$) in the\nperpendicular direction. The confinement provided by the LC matrix is also\nreflected by oscillatory behavior of the components of the velocity\nautocorrelation function of the DSS in the nematic phase.",
        "positive": "Random close packing of granular matter: We propose an interpretation of the random close packing of granular\nmaterials as a phase transition, and discuss the possibility of experimental\nverification."
    },
    {
        "anchor": "New mechanism of membrane fusion: We have carried out Monte Carlo simulation of the fusion of bilayers of\nsingle chain amphiphiles which show phase behavior similar to that of\nbiological lipids. The fusion mechanism we observe is very different from the\n``stalk'' hypothesis. Stalks do form on the first stage of fusion, but they do\nnot grow radially to form a hemifused state. Instead, stalk formation\ndestabilizes the membranes and results in hole formation in the vicinity of the\nstalks. When holes in each bilayer nucleate spontaneously next to the same\nstalk, an incomplete fusion pore is formed. The fusion process is completed by\npropagation of the initial connection, the stalk, along the edges of the\naligned holes.",
        "positive": "Crystalline membrane morphology beyond polyhedra: Elastic crystalline membranes exhibit a buckling transition from sphere to\npolyhedron. However, their morphologies are restricted to convex polyhedra and\nare difficult to externally control. Here, we study morphological changes of\nclosed crystalline membrane of super-paramagnetic particles. The competition of\nmagnetic dipole-dipole interactions with the elasticity of this magnetoelastic\nmembrane leads to concave morphologies. Interestingly, as the magnetic field\nstrength increases, the symmetry of the buckled membrane decreases from 5-fold\nto 3-fold, to 2-fold and, finally, to 1-fold rotational symmetry. This gives\nthe ability to switch the membrane morphology between convex and concave shapes\nwith specific symmetry and provides promising applications for membrane shape\ncontrol in the design of actuatable micro-containers for targeted delivery\nsystems."
    },
    {
        "anchor": "Distribution of local relaxation events in an aging 3D glass:\n  spatio-temporal correlation and dynamical heterogeneity: We investigate the spatio-temporal distribution of microscopic relaxation\nevents, defined through particle hops, in a model polymer glass using molecular\ndynamics simulations. We introduce an efficient algorithm to directly identify\nhops during the simulation, which allows the creation of a map of relaxation\nevents for the whole system. Based on this map, we present density-density\ncorrelations between hops and directly extract correlation scales. These scales\ndefine collaboratively rearranging groups of particles and their size\ndistributions are presented as a function of temperature and age. Dynamical\nheterogeneity is spatially resolved as the aggregation of hops into clusters,\nand we analyze their volume distribution and growth during aging. A direct\ncomparison with the four-point dynamical susceptibility {\\chi}4 reveals the\nformation of a single dominating cluster prior to the {\\chi}4 peak, which\nindicates maximally correlated dynamics. An analysis of the fractal dimension\nof the hop clusters finds slightly non-compact shapes in excellent agreement\nwith independent estimates from four-point correlations.",
        "positive": "Liquid Crystal Colloids: Colloids are abundant in nature, science and technology, with examples\nranging from milk to quantum dots and the \"colloidal atom\" paradigm. Similarly,\nliquid crystal ordering is important in contexts ranging from biological\nmembranes to laboratory models of cosmic strings and liquid crystal displays in\nconsumer devices. Some of the most exciting recent developments in both of\nthese soft matter fields emerge at their interface, in the fast-growing\nresearch arena of liquid crystal colloids. Mesoscale self-assembly in such\nsystems may lead to artificial materials and structures with emergent physical\nbehavior arising from patterning of molecular order and nano- or\nmicro-particles into precisely controlled configurations. Liquid crystal\ncolloids show an exceptional promise of new discovery that may impinge on the\ncomposite material fabrication, low-dimensional topology, photonics, and so on.\nStarting from physical underpinnings, I review the state of art in this\nfast-growing field, with a focus on its scientific and technological potential."
    },
    {
        "anchor": "How wet should be the reaction coordinate for ligand unbinding?: We use a recently proposed method called Spectral Gap Optimization of Order\nParameters (SGOOP) (Tiwary and Berne, Proc. Natl. Acad. Sci 2016, 113, 2839\n(2016)), to determine an optimal 1-dimensional reaction coordinate (RC) for the\nunbinding of a bucky-ball from a pocket in explicit water. This RC is estimated\nas a linear combination of the multiple available order parameters that\ncollectively can be used to distinguish the various stable states relevant for\nunbinding. We pay special attention to determining and quantifying the degree\nto which water molecules should be included in the RC. Using SGOOP with\nunder-sampled biased simulations, we predict that water plays a distinct role\nin the reaction coordinate for unbinding in the case when the ligand is\nsterically constrained to move along an axis of symmetry. This prediction is\nvalidated through extensive calculations of the unbinding times through\nmetadynamics, and by comparison through detailed balance with unbiased\nmolecular dynamics estimate of the binding time. However when the steric\nconstraint is removed, we find that the role of water in the reaction\ncoordinate diminishes. Here instead SGOOP identifies a good one-dimensional RC\ninvolving various motional degrees of freedom.",
        "positive": "More than one dynamic crossover in protein hydration water: Studies of liquid water in its supercooled region have led to many insights\ninto the structure and behavior of water. While bulk water freezes at its\nhomogeneous nucleation temperature of approximately 235 K, for protein\nhydration water, the binding of water molecules to the protein avoids\ncrystallization. Here we study the dynamics of the hydrogen bond (HB) network\nof a percolating layer of water molecules, comparing measurements of a hydrated\nglobular protein with the results of a coarse-grained model that has been shown\nto successfully reproduce the properties of hydration water. With dielectric\nspectroscopy we measure the temperature dependence of the relaxation time of\nprotons charge fluctuations. These fluctuations are associated to the dynamics\nof the HB network of water molecules adsorbed on the protein surface. With\nMonte Carlo (MC) simulations and mean--field (MF) calculations we study the\ndynamics and thermodynamics of the model. In both experimental and model\nanalyses we find two dynamic crossovers: (i) one at about 252 K, and (ii) one\nat about 181 K. The agreement of the experiments with the model allows us to\nrelate the two crossovers to the presence of two specific heat maxima at\nambient pressure. The first is due to fluctuations in the HB formation, and the\nsecond, at lower temperature, is due to the cooperative reordering of the HB\nnetwork."
    },
    {
        "anchor": "Camphor-Engine-Driven Micro-Boat Guides Evolution of Chemical Gardens: A micro-boat self-propelled by a camphor engine, carrying seed crystals of\nFeCl3, promoted the evolution of chemical gardens when placed on the surface of\naqueous solutions of potassium hexacyanoferrate. Inverse chemical gardens\n(growing from the top downward) were observed. The growth of the inverse\nchemical gardens was slowed down with an increase in the concentration of the\npotassium hexacyanoferrate. Heliciform precipitates were formed under the\nself-propulsion of the micro-boat. A phenomenological model, satisfactorily\ndescribing the self locomotion of the camphor-driven micro-boat, is introduced\nand checked.",
        "positive": "Bubble Statistics and Dynamics in Double-Stranded DNA: The dynamical properties of double-stranded DNA are studied in the framework\nof the Peyrard-Bishop-Dauxois model using Langevin dynamics. Our simulations\nare analyzed in terms of two probability functions describing coherently\nlocalized separations (\"bubbles\") of the double strand. We find that the\nresulting bubble distributions are more sharply peaked at the active sites than\nfound in thermodynamically obtained distributions. Our analysis ascribes this\nto the fact that the bubble life-times significantly afects the distribution\nfunction. We find that certain base-pair sequences promote long-lived bubbles\nand we argue that this is due to a length scale competition between the\nnonlinearity and disorder present in the system."
    },
    {
        "anchor": "The Importance of Boundary Conditions for Fluctuation Induced Forces\n  between Colloids at Interfaces: We calculate the effective fluctuation induced force between spherical or\ndisk-like colloids trapped at a flat, fluid interface mediated by thermally\nexcited capillary waves. This Casimir type force is determined by the partition\nfunction of the system which in turn is calculated in a functional integral\napproach, where the restrictions on the capillary waves imposed by the colloids\nare incorporated by auxiliary fields. In the long-range regime the fluctuation\ninduced force is shown to depend sensitively on the boundary conditions imposed\nat the three-phase contact line between the colloids and the two fluid phases.\nThe splitting of the fluctuating capillary wave field into a mean-field and a\nfluctuation part leads to competing repulsive and attractive contributions,\nrespectively, which give rise to cancellations of the leading terms. In a\nsecond approach based on multipole expansion of the Casimir interaction, these\ncancellations can be understood from the vanishing of certain multipole moments\nenforced by the boundary conditions. We also discuss the connection of the\ndifferent types of boundary conditions to certain external fields acting on the\ncolloids which appear to be realizable by experimental techniques such as the\nlaser tweezer method.",
        "positive": "Propulsion and instability of a flexible helical rod rotating in a\n  viscous fluid: We combine experiments with simulations to investigate the fluid-structure\ninteraction of a flexible helical rod rotating in a viscous fluid, under low\nReynolds number conditions. Our analysis takes into account the coupling\nbetween the geometrically nonlinear behavior of the elastic rod with a\nnon-local hydrodynamic model for the fluid loading. We quantify the resulting\npropulsive force, as well as the buckling instability of the originally helical\nfilament that occurs above a critical rotation velocity. A scaling analysis is\nperformed to rationalize the onset of this instability. A universal phase\ndiagram is constructed to map out the region of successful propulsion and the\ncorresponding boundary of stability are established. Comparing our results with\ndata for flagellated bacteria suggests that this instability may be exploited\nin nature for physiological purposes."
    },
    {
        "anchor": "Perspective: Atomistic Simulations of Water and Aqueous Systems with\n  Machine Learning Potentials: As the most important solvent, water has been at the center of interest since\nthe advent of computer simulations. While early molecular dynamics and Monte\nCarlo simulations had to make use of simple model potentials to describe the\natomic interactions, accurate ab initio molecular dynamics simulations relying\non the first-principles calculation of the energies and forces have opened the\nway to predictive simulations of aqueous systems. Still, these simulations are\nvery demanding, which prevents the study of complex systems and their\nproperties. Modern machine learning potentials (MLPs) have now reached a mature\nstate, allowing to overcome these limitations by combining the high accuracy of\nelectronic structure calculations with the efficiency of empirical force\nfields. In this Perspective we give a concise overview about the progress made\nin the simulation of water and aqueous systems employing MLPs, starting from\nearly work on free molecules and clusters via bulk liquid water to electrolyte\nsolutions and solid-liquid interfaces.",
        "positive": "Non-Euclidean geometry in nature: I describe the manifestation of the non-Euclidean geometry in the behavior of\ncollective observables of some complex physical systems. Specifically, I\nconsider the formation of equilibrium shapes of plants and statistics of sparse\nrandom graphs. For these systems I discuss the following interlinked questions:\n(i) the optimal embedding of plants leaves in the three-dimensional space, (ii)\nthe spectral statistics of sparse random matrix ensembles."
    },
    {
        "anchor": "Propagation of hydrodynamic interactions between particles in a\n  compressible fluid: Hydrodynamic interactions are transmitted by viscous diffusion and sound\npropagation: the temporal evolution of hydrodynamic interactions by both\nmechanisms is studied by direct numerical simulation in this paper. The\nhydrodynamic interactions for a system of two particles in a fluid are\nestimated by the velocity correlation of the particles. In an incompressible\nfluid, hydrodynamic interactions propagate instantaneously at the infinite\nspeed of sound, followed by the temporal evolution of viscous diffusion. On the\nother hand, in a compressible fluid, sound propagates at a finite speed, which\naffects the temporal evolution of the hydrodynamic interactions by the order of\nmagnitude relation between the time scales of viscous diffusion and sound\npropagation. The hydrodynamic interactions are characterized by introducing the\nratio of these time scales as an interactive compressibility factor.",
        "positive": "Electrolyte solutions at curved electrodes. I. Mesoscopic approach: Within the Poisson-Boltzmann (PB) approach electrolytes in contact with\nplanar, spherical, and cylindrical electrodes are analyzed systematically. The\ndependences of their capacitance $C$ on the surface charge density $\\sigma$ and\nthe ionic strength $I$ are examined as function of the wall curvature. The\nsurface charge density has a strong effect on the capacitance for small\ncurvatures whereas for large curvatures the behavior becomes independent of\n$\\sigma$. An expansion for small curvatures gives rise to capacitance\ncoefficients which depend only on a single parameter, allowing for a convenient\nanalysis. The universal behavior at large curvatures can be captured by an\nanalytic expression."
    },
    {
        "anchor": "Exact bulk correlation functions in one-dimensional nonadditive\n  hard-core mixtures: In a recent paper [Phys. Rev. E \\textbf{76}, 031202 (2007)], Schmidt has\nproposed a Fundamental Measure Density Functional Theory for one-dimensional\nnonadditive hard-rod fluid mixtures and has compared its predictions for the\nbulk structural properties with Monte Carlo simulations. The aim of this Brief\nReport is to recall that the problem admits an exact solution in the bulk,\nwhich is briefly summarized in a self-contained way.",
        "positive": "A cyclic stress softening model for the Mullins effect: In this paper the inelastic features of stress relaxation, hysteresis and\nresidual strain are combined with the Arruda-Boyce eight-chain model of\nelasticity, in order to develop a model that is capable of describing the\nMullins effect for cyclic stress-softening of an incompressible hyperelastic\nmaterial, in particular a carbon-filled rubber vulcanizate. We have been unable\nto identify in the literature any other model that takes into consideration all\nthe above inelastic features of the cyclic stress-softening of carbon-filled\nrubber. Our model compares favourably with experimental data and gives a good\ndescription of stress-softening, hysteresis, stress relaxation, residual strain\nand creep of residual strain. Keywords: Mullins effect, stress-softening,\nhysteresis, stress relaxation, residual strain, creep of residual strain. MSC\ncodes: 74B20, 74D10, 74L1"
    },
    {
        "anchor": "Poisson Bracket Formulation of Nematic Polymer Dynamics: We formulate the dynamical theory of nematic polymers, starting from a\nmicroscopic Poisson bracket approach. We find that the Poisson bracket between\nthe nematic director and momentum depends on the (Maier-Saupe) order parameter\nof the nematic phase. We use this to derive reactive couplings of the nematic\ndirector to the strain rates. Additionally, we find that local dynamics breaks\ndown as the polymers begin to overlap. We offer a physical picture for both\nresults.",
        "positive": "Controlling effective dispersion within a channel with flow and active\n  walls: Channels are fundamental building blocks from biophysics to soft robotics,\noften used to transport or separate solutes. As solute particles inevitably\ntransverse between streamlines along the channel by molecular diffusion, the\neffective diffusion of the solute along the channel is enhanced - an effect\nknown as Taylor dispersion. Here, we investigate how the Taylor dispersion\neffect can be suppressed or enhanced in different settings. Specifically, we\nstudy the impact of flow profile and active or pulsating channel walls on\nTaylor dispersion. We derive closed analytic expressions for the effective\ndispersion equation in all considered scenarios providing hands-on effective\ndispersion parameters for a multitude of applications. In particular, we find\nthat active channel walls may lead to three regimes of dispersion: either\ndispersion decrease by entropic slow down at small Peclet number, or dispersion\nincrease at large Peclet number dominated either by shuttle dispersion or by\nTaylor dispersion. This improves our understanding of solute transport e.g. in\nbiological active systems such as blood flow and opens a number of\npossibilities to control solute transport in artificial systems such as soft\nrobotics."
    },
    {
        "anchor": "Transport powered by bacterial turbulence: We demonstrate that collective turbulent-like motion in a bacterial bath can\npower and steer directed transport of mesoscopic carriers through the\nsuspension. In our experiments and simulations, a microwedge-like \"bulldozer\"\ndraws energy from a bacterial bath of varied density. We obtain that a maximal\ntransport speed is achieved in the turbulent state of the bacterial suspension.\nThis apparent rectification of random motion of bacteria is caused by polar\nordered bacteria inside the cusp region of the carrier, which is shielded from\nthe outside turbulent fluctuations.",
        "positive": "Entropic origin of dielectric relaxation universalities in heterogeneous\n  materials (polymers, glasses, aerogel catalysts): We have derived a universal relaxation function for heterogeneous materials\nusing the maximum entropy principle for nonextensive systems. The power law\nexponents of the relaxation function are simply related to a global fractal\nparameter and for large time to the entropy nonextensivity parameter q. For\nintermediate times the relaxation follows a stretched exponential behavior. The\nasymptotic power law behaviors both in the time and the frequency domains\ncoincide with those of the Weron generalized dielectric function derived in the\nstochastic theory from an extension of the Levy central limit theorem. These\nresults are in full agreement with the Jonscher universality principle and find\napplication in the characterization of the dielectric properties of aerogels\ncatalytic supports as well as in the problem of the relation between morphology\nand dielectric properties of polymer composites."
    },
    {
        "anchor": "Contact mechanics of adhesive beams. Part I: Moderate indentation: We investigate the contact of a rigid cylindrical punch with an adhesive beam\nmounted on flexible end supports. Adhesion is modeled through an adhesive zone\nmodel. The resulting Fredholm integral equation of the first kind is solved by\na Galerkin projection method in terms of Chebyshev polynomials. Results are\nreported for several combinations of adhesive strengths, beam thickness, and\nsupport flexibilities characterized through torsional and vertical\ntranslational spring stiffnesses. Special attention is paid to the important\nextreme cases of clamped and simply supported beams. The popular\nJohnson-Kendall-Roberts (JKR) model for adhesion is obtained as a limit of the\nadhesive zone model. Finally, we compare our predictions with preliminary\nexperiments and also demonstrate the utility of our approach in modeling\ncomplex structural adhesives.",
        "positive": "Ordering of block copolymer microstructures in corner geometries: The ordering of block copolymers into lamellar microstructures is an\nattractive route for creating nanopatterns on scales too small to be\nconstructed by current photolithography techniques. This utilises a technique\nknown as graphoepitaxy where topography is used to define the alignment of the\npattern for precise placement of pattern features. One problem with this\napproach is the failure of lamellae to maintain continuity around corners, due\nto geometrical frustration. We report simulation results using the extended\nCahn-Hilliard equation which suggest that this problem could be solved by using\nrounded corners."
    },
    {
        "anchor": "Microphase Equilibrium and Assembly Dynamics: Despite many attempts, ordered equilibrium microphases have yet to be\nobtained in experimental colloidal suspensions. The recent computation of the\nequilibrium phase diagram of a microscopic, particle-based microphase former\n[Zhuang et al., Phys. Rev. Lett. 116, 098301 (2016)] has nonetheless found such\nmesoscale assemblies to be thermodynamically stable. Here, we consider their\nequilibrium and assembly dynamics. At intermediate densities above the\norder-disorder transition, we identify four different dynamical regimes and the\nstructural changes that underlie the dynamical crossovers from one disordered\nregime to the next. Below the order-disorder transition, we also find that\nperiodic lamellae are the most dynamically accessible of the periodic\nmicrophases. Our analysis thus offers a comprehensive view of the disordered\nmicrophase dynamics and a route to the assembly of periodic microphases in a\nputative well-controlled, experimental system.",
        "positive": "Self-crumpling elastomers: bending induced by the drying stimulus of a\n  nanoparticle suspension: We report an experimental study of the drying-induced peeling of a bilayer,\nconsisting of an elastomeric disk coated with a suspension of nanoparticles. We\nshow that although capillary forces associated with the scale of the droplet\ncan not compete with the adhesion of the elastomer on a surface, nevertheless\nlarge tensile stresses develop in the coating, which results in a moment\nbending the bilayer. We attribute this stress to the nano-menisci in the pores\nof the colloidal material and we propose a model that describes successfully\nthe early stage curvature of the bilayer. Thus, we show that the peeling can be\nconveniently controlled by the particle size and the coating thickness."
    },
    {
        "anchor": "Interaction between catalytic micro motors: Starting from a microscopic model for a spherically symmetric active Janus\nparticle, we study the interactions between two such active motors. The ambient\nfluid mediates a long range hydrodynamic interaction between two motors. This\ninteraction has both direct and indirect hydrodynamic contributions. The direct\ncontribution is due to the propagation of fluid flow that originated from a\nmoving motor and affects the motion of the other motor. The indirect\ncontribution emerges from the re-distribution of the ionic concentrations in\nthe presence of both motors. Electric force exerted on the fluid from this\nionic solution enhances the flow pattern and subsequently changes the motion of\nboth motors. By formulating a perturbation method for very far separated\nmotors, we derive analytic results for the transnational and rotational\ndynamics of the motors. We show that the overall interaction at the leading\norder, modifies the translational and rotational speeds of motors which scale\nas ${\\cal O}\\left([1/D]^3\\right)$ and ${\\cal O}\\left([1/D]^4\\right)$ with their\nseparation, respectively. Our findings open up the way for studying the\ncollective dynamics of synthetic micro motors.",
        "positive": "Predicting the DNA Conductance using Deep Feed Forward Neural Network\n  Model: Double-stranded DNA (dsDNA) has been established as an efficient medium for\ncharge migration, bringing it to the forefront of the field of molecular\nelectronics as well as biological research. The charge migration rate is\ncontrolled by the electronic couplings between the two nucleobases of DNA/RNA.\nThese electronic couplings strongly depend on the intermolecular geometry and\norientation. Estimating these electronic couplings for all the possible\nrelative geometries of molecules using the computationally demanding\nfirst-principles calculations requires a lot of time as well as computation\nresources. In this article, we present a Machine Learning (ML) based model to\ncalculate the electronic coupling between any two bases of dsDNA/dsRNA of any\nlength and sequence and bypass the computationally expensive first-principles\ncalculations. Using the Coulomb matrix representation which encodes the atomic\nidentities and coordinates of the DNA base pairs to prepare the input dataset,\nwe train a feedforward neural network model. Our NN model can predict the\nelectronic couplings between dsDNA base pairs with any structural orientation\nwith a MAE of less than 0.014 eV. We further use the NN predicted electronic\ncoupling values to compute the dsDNA/dsRNA conductance."
    },
    {
        "anchor": "q-dependence of low-frequency Raman scattering in silica glass: Accurate measurements of the dependence of low-frequency Raman scattering on\nthe scattering angle were performed in two silica glasses. By a comparison of\nspectra measured at a large scattering angle (close to back scattering) and a\nsmall one (close to forward scattering), we for the first time observed a\nq-dependence of the low-frequency light scattering in glasses. From the\nmagnitude of the effect, the vibration correlation length is estimated and\ncompared with results from the picosecond optical technique; a reasonable\nagreement is found.",
        "positive": "Time correlation functions in Vibration-Transit theory of liquid\n  dynamics: Within the framework of V-T theory of monatomic liquid dynamics, an exact\nequation is derived for a general equilibrium time correlation function. The\npurely vibrational contribution to such a function expresses the system's\nmotion in one extended harmonic random valley. This contribution is\nanalytically tractable and has no adjustable parameters. While this\ncontribution alone dominates the thermodynamic properties, both vibrations and\ntransits will make important contributions to time correlation functions. By\nway of example, the V-T formulation of time correlation functions is applied to\nthe dynamic structure factor S(q,w). The vibrational contribution alone is\nshown to be in near perfect agreement with low-temperature molecular dynamics\nsimulations, and a model simulating the transit contribution with three\nadjustable parameters achieves equally good agreement with molecular dynamics\nresults in the liquid regime. The theory indicates that transits will broaden\nwithout shifting the Rayleigh and Brillouin peaks in S(q,w), and this behavior\nis confirmed by the MD calculations. We find the vibrational contribution alone\ngives the location and much of the width of the liquid-state Brillouin peak. We\nalso discuss this approach to liquid dynamics compared with potential energy\nlandscape formalisms and mode coupling theory, drawing attention to the\ndistinctive features of our approach and to some potential energy landscape\nresults which support our picture of the liquid state."
    },
    {
        "anchor": "Growing length scale accompanying the vitrification: A perspective based\n  on non-singular density fluctuations: In glass forming liquids close to the glass transition point, even a very\nslight increase in the macroscopic density results in a dramatic slowing down\nof the macroscopic relaxation. Concomitantly, the local density itself\nfluctuates in space. Therefore, one can imagine that even very small local\ndensity variations control the local glassy nature. Based on this perspective,\na model for describing growing length scale accompanying the vitrification is\nintroduced, in which we assume that in a subsystem whose density is above a\ncertain threshold value, $\\rho_{\\rm c}$, owing to steric constraints, particle\nrearrangements are highly suppressed for a sufficiently long time period\n($\\sim$ structural relaxation time). We regard such a subsystem as a glassy\ncluster. Then, based on the statistics of the subsystem-density, we predict\nthat with compression (increasing average density $\\rho$) at a fixed\ntemperature $T$ in supercooled states, the characteristic length of the\nclusters, $\\xi$, diverges as $\\xi\\sim(\\rho_{\\rm c}-\\rho)^{-2/d}$, where $d$ is\nthe spatial dimensionality. This $\\xi$ measures the average persistence length\nof the steric constraints in blocking the rearrangement motions and is\ndetermined by the subsystem density. Additionally, with decreasing $T$ at a\nfixed $\\rho$, the length scale diverges in the same manner as $\\xi\\sim(T-T_{\\rm\nc})^{-2/d}$, for which $\\rho$ is identical to $\\rho_{\\rm c}$ at $T=T_{\\rm c}$.\nThe exponent describing the diverging length scale is the same as the one\npredicted by some theoretical models and indeed has been observed in some\nsimulations and experiments. However, the basic mechanism for this divergence\nis different; that is, we do not invoke thermodynamic anomalies associated with\nthe thermodynamic phase transition as the origin of the growing length scale.\nWe further present arguements for the cooperative properties based on the\nclusters.",
        "positive": "Active Particles as Mobile Microelectrodes for Selective Bacteria\n  Electroporation and Transport: Self-propelling micromotors are emerging as a promising microscale and\nnanoscale tool for single-cell analysis. We have recently shown that the field\ngradients necessary to manipulate matter via dielectrophoresis can be induced\nat the surface of a polarizable active (self-propelling) metallo-dielectric\nJanus particle (JP) under an externally applied electric field, acting\nessentially as a mobile floating microelectrode. Here, we successfully\ndemonstrated for the first time, that the application of an external electric\nfield can singularly trap and transport bacteria and can selectively\nelectroporate the trapped bacteria. Selective electroporation, enabled by the\nlocal intensification of the electric field induced by the JP, was obtained\nunder both continuous alternating current and pulsed signal conditions. This\napproach is generic and is applicable to bacteria and JP, as well as a wide\nrange of cell types and micromotor designs. Hence, it constitutes an important\nand novel experimental tool for single-cell analysis and targeted delivery."
    },
    {
        "anchor": "Non-monotonic dependence of the rupture force in polymer chains on their\n  lengths: We consider the rupture dynamics of a homopolymer chain pulled at one end at\na constant loading rate. Our model of the breakable polymer is related to the\nRouse chain, with the only difference that the interaction between the monomers\nis described by the Morse potential instead of the harmonic one, and thus\nallows for mechanical failure. We show that in the experimentally relevant\ndomain of parameters the dependence of the most probable rupture force on the\nchain length may be non-monotonic, so that the medium-length chains break\neasier than the short and the long ones. The qualitative theory of the effect\nis presented.",
        "positive": "Fluorescent visualization of a spreading surfactant: The spreading of surfactants on thin films is an industrially and medically\nimportant phenomenon, but the dynamics are highly nonlinear and visualization\nof the surfactant dynamics has been a long-standing experimental challenge. We\nperform the first quantitative, spatiotemporally-resolved measurements of the\nspreading of an insoluble surfactant on a thin fluid layer. During the\nspreading process, we directly observe both the radial height profile of the\nspreading droplet and the spatial distribution of the fluorescently-tagged\nsurfactant. We find that the leading edge of spreading circular layer of\nsurfactant forms a Marangoni ridge in the underlying fluid, with a trough\ntrailing the ridge as expected. However, several novel features are observed\nusing the fluorescence technique, including a peak in the surfactant\nconcentration which trails the leading edge, and a flat, monolayer-scale\nspreading film which differs from concentration profiles predicted by current\nmodels. Both the Marangoni ridge and surfactant leading edge can be described\nto spread as $R \\propto t^{\\delta}$. We find spreading exponents, $\\delta_H\n\\approx 0.30$ and $\\delta_\\Gamma \\approx 0.22$ for the ridge peak and\nsurfactant leading edge, respectively, which are in good agreement with\ntheoretical predictions of $\\delta = 1/4$. In addition, we observe that the\nsurfactant leading edge initially leads the peak of the Marangoni ridge, with\nthe peak later catching up to the leading edge."
    },
    {
        "anchor": "Granular Gas: Vibrating Walls, Two-Peak Distribution and Hydrodynamics: Vibrating walls, used to maintain the temperature in a granular gas, modify\nthe system strongly. Most conspicuously, the usual one-peak velocity\ndistribution splits into two, asymmetrically positioned. A surgical repair of\nthe usual hydrodynamic description is presented that provides an account for,\nand an understanding of, the situation.",
        "positive": "Asymptotic analysis of conversion-limited phase separation: Liquid-liquid phase separation plays a major role in the formation and\nmaintenance of various membrane-less subcellular structures in the cytoplasm\nand nucleus of cells. Biological condensates contain enhanced concentrations of\nproteins and RNA, many of which can be continually exchanged with the\nsurrounding medium. Coarsening is an important step in the kinetics of phase\nseparation, whereby an emulsion of polydisperse condensates transitions to a\nsingle condensate in thermodynamic equilibrium with a surrounding dilute phase.\nA key feature of biological phase separation is the co-existence of multiple\ncondensates over significant time scales, which is consistent with experimental\nobservations showing a slowing of coarsening rates. It has recently been\nproposed that one rate limiting step could be the slow interfacial conversion\nof a molecular constituent between the dilute and dense phases. In this paper\nwe analyze conversion-limited phase separation within the framework of\ndiffusion in singularly perturbed domains, which exploits the fact that\nbiological condensates tend to be much smaller than the size of a cell. Using\nmatched asymptotic analysis, we solve the quasi-static diffusion equation for\nthe concentration in the dilute phase, and then derive kinetic equations for\nthe slow growth/shrinkage of the condensates. This provides a systematic way of\nobtaining corrections to mean-field theory that take into account the geometry\nof the cell and the locations of all the condensates."
    },
    {
        "anchor": "Power-law creep and residual stresses in a carbopol microgel: We report on the interplay between creep and residual stresses in a carbopol\nmicrogel. When a constant shear stress $\\sigma$ is applied below the yield\nstress $\\sigma_\\text{y}$, the strain is shown to increase as a power law of\ntime, $\\gamma(t)=\\gamma_0 + (t/\\tau)^\\alpha$, with an exponent $\\alpha=0.39\\pm\n0.04$ that is strongly reminiscent of Andrade creep in hard solids. For applied\nshear stresses lower than some typical value $\\sigma_\\text{c}\\simeq 0.2\n\\sigma_\\text{y}$, the microgel experiences a more complex, anomalous creep\nbehaviour, characterized by an initial decrease of the strain, that we\nattribute to the existence of residual stresses of the order of\n$\\sigma_\\text{c}$ that persist after a rest time under a zero shear rate\nfollowing preshear. The influence of gel concentration on creep and residual\nstresses are investigated as well as possible aging effects. We discuss our\nresults in light of previous works on colloidal glasses and other soft glassy\nsystems.",
        "positive": "Bundling in brushes of directed and semiflexible polymers: We explore the effect of an attractive interaction between parallel-aligned\npolymers, which are perpendicularly grafted on a substrate. Such an attractive\ninteraction could be due to, e.g., reversible cross-links. The competition\nbetween permanent grafting favoring a homogeneous state of the polymer brush\nand the attraction, which tends to induce in-plane collapse of the aligned\npolymers, gives rise to an instability of the homogeneous phase to a bundled\nstate. In this latter state the in-plane translational symmetry is\nspontaneously broken and the density is modulated with a finite wavelength,\nwhich is set by the length scale of transverse fluctuations of the grafted\npolymers. We analyze the instability for two models of aligned polymers:\ndirected polymers with a line tension and weakly bending chains with a bending\nstiffness."
    },
    {
        "anchor": "X-ray nanotomography reveals formation of single diamonds by block\n  copolymer self-assembly: Block copolymers are recognised as a valuable platform for creating\nnanostructured materials with unique properties. Morphologies formed by block\ncopolymer self-assembly can be transferred into a wide range of inorganic\nmaterials, enabling applications including energy storage and metamaterials.\nHowever, imaging of the underlying, often complex, nanostructures in large\nvolumes has remained a challenge, limiting progress in materials development.\nTaking advantage of recent advances in X-ray nanotomography, we non-invasively\nimaged exceptionally large volumes of nanostructured soft materials at high\nresolution, revealing a single diamond morphology in a triblock terpolymer\ncomposite network. This morphology, which is ubiquitous in nature, has so far\nremained elusive in block copolymers, despite its potential to create materials\nwith large photonic bandgaps. The discovery was made possible by the precise\nanalysis of distortions in a large volume of the self-assembled diamond\nnetwork, which are difficult to unambiguously assess using traditional\ncharacterisation tools. We anticipate that high-resolution X-ray\nnanotomography, which allows imaging of much larger sample volumes than\nelectron-based tomography, will become a powerful tool for the quantitative\nanalysis of complex nanostructures and that structures such as the triblock\nterpolymer-directed single diamond will enable the generation of advanced\nmulticomponent composites with hitherto unknown property profiles.",
        "positive": "Probabilistic buckling of imperfect hemispherical shells containing a\n  distribution of defects: The buckling of spherical shells is plagued by a strong sensitivity to\nimperfections. Traditionally, imperfect shells tend to be characterized\nempirically by the knockdown factor, the ratio between the measured buckling\nstrength and the corresponding classic prediction for a perfect shell.\nRecently, it has been demonstrated that the knockdown factor of a shell\ncontaining a single imperfection can be predicted when there is detailed a\npriori knowledge of the defect geometry. Still, addressing the analogous\nproblem for a shell containing many defects remains an open question. Here, we\nuse finite element simulations, which we validate against precision\nexperiments, to investigate hemispherical shells containing a well-defined\ndistribution of imperfections. Our goal is to characterize the resulting\nknockdown factor statistics. First, we study the buckling of shells containing\nonly two defects, uncovering nontrivial regimes of interactions that echo\nexisting findings for cylindrical shells. Then, we construct statistical\nensembles of imperfect shells, whose defect amplitudes are sampled from a\nlognormal distribution. We find that a 3-parameter Weibull distribution is an\nexcellent description for the measured statistics of knockdown factors,\nsuggesting that shell buckling can be regarded as an extreme-value statistics\nphenomenon."
    },
    {
        "anchor": "Friction of a slider on a granular layer: Non-monotonic thickness\n  dependence and effect of boundary conditions: We investigate the effective friction encountered by a mass sliding on a\ngranular layer as a function of bed thickness and boundary roughness\nconditions. The observed friction has minima for a small number of layers\nbefore it increases and saturates to a value which depends on the roughness of\nthe sliding surface. We use an index-matched interstitial liquid to probe the\ninternal motion of the grains with fluorescence imaging in a regime where the\nliquid has no significant effect on the measured friction. The shear profiles\nobtained as a function of depth show decrease in slip near the sliding surface\nas the layer thickness is increased. We propose that the friction depends on\nthe degree of grain confinement relative to the sliding surfaces.",
        "positive": "Explicit Solvent Theory of Salt-Induced Dielectric Decrement: We introduce a field-theoretic electrolyte model composed of structured\nsolvent molecules and salt ions coupled by electrostatic and hard-core\ninteractions. Within this explicit solvent theory, we characterize the\nsalt-driven dielectric decrement beyond weak-coupling (WC) electrostatics. The\nWC approximation of prior formalisms is relaxed by treating the salt charges\nvia a virial expansion. This virial approach enables the explicit inclusion of\nthe many-body salt-solvent interactions, and directly leads to the\nexperimentally observed linear decay of the electrolyte permittivity with added\ndilute salt. The permittivity formula emerging from our approach indicates that\nthe reduction of the solvent permittivity is induced by the salt screening of\nthe polarization charges suppressing the dielectric response of the solvent. By\ncomparison with experiments, we also show that the salt-dressed permittivity\nformula can equally reproduce the attenuation of the electrolyte permittivity\nwith rising temperature, the thermal decay of the dielectric decrement, and its\nintensification with the salt valency. The consistent qualitative agreement of\nour theory with this wide range of experimental trends points out the\nelectrostatic ion-solvent correlations as the primary mechanism behind the\nsalt-induced dielectric decrement."
    },
    {
        "anchor": "Note: An exact scaling relation for truncatable free energies of\n  polydisperse hard-sphere mixtures: A theoretical model for polydisperse systems of hard spheres is said to be\ntruncatable when the excess free energy depends on the size distribution\nthrough a finite number $K$ of moments. This Note proves an exact scaling\nrelation for truncatable free energies, which allows to reduce the effective\ndegrees of freedom to $K-2$ independent combinations of the moments.",
        "positive": "Mixtures of Hard Ellipsoids and Spheres: Stability of the Nematic Phase: The stability of liquid crystal phases in presence of small amount of\nnon-mesogenic impurities is of general interest for a large spectrum of\ntechnological applications and in the theories of binary mixtures. Starting\nfrom the known phase diagram of the hard ellipsoids systems, we propose a\nsimple model and method to explore the stability of the nematic phase in\npresence of small impurities represented by hard spheres. The study is\nperformed in the isobaric ensemble with Monte Carlo simulations."
    },
    {
        "anchor": "Irreversible Aging Dynamics and Generic Phase Behavior of Aqueous\n  Suspensions of Laponite: In this work we study the aging behavior of aqueous suspension of Laponite\nhaving 2.8 weight % concentration using rheological tools. At various salt\nconcentration all the samples demonstrate orientational order when observed\nusing crossed polarizers. In rheological experiments we observe inherent\nirreversibility in the aging dynamics which forces the system not to rejuvenate\nto the same state in the shear melting experiment carried out at a later date\nsince preparation. The extensive rheological experiments carried out as a\nfunction of time elapsed since preparation demonstrate the self similar trend\nin the aging behavior irrespective of the concentration of salt. We observe\nthat the exploration of the low energy states as a function of aging time is\nonly kinetically affected by the presence of salt. We estimate that the energy\nbarrier to attain the low energy states decreases linearly with increase in the\nconcentration of salt. The observed superposition of all the elapsed time and\nthe salt concentration dependent data suggests that the aging that occurs in\nlow salt concentration systems over a very long period is qualitatively similar\nto the aging behavior observed in systems with high salt concentration over a\nshorter period.",
        "positive": "Semi-flexible hydrogen-bonded and non-hydrogen bonded lattice polymers: We investigate the addition of stiffness to the lattice model of\nhydrogen-bonded polymers in two and three dimensions. We find that, in contrast\nto polymers that interact via a homogeneous short-range interaction, the\ncollapse transition is unchanged by any amount of stiffness: this supports the\nphysical argument that hydrogen bonding already introduces an effective\nstiffness. Contrary to possible physical arguments, favouring bends in the\npolymer does not return the model's behaviour to that comparable to the\nsemi-flexible homogeneous interaction model, where the canonical $\\theta$-point\noccurs for a range of parameter values. In fact, for sufficiently large bending\nenergies the crystal phase disappears altogether, and no phase transition of\nany type occurs. We also compare the order-disorder transition from the globule\nphase to crystalline phase in the semi-flexible homogeneous interaction model\nto that for the fully-flexible hybrid model with both hydrogen and non-hydrogen\nlike interactions. We show that these phase transitions are of the same type\nand are a novel polymer critical phenomena in two dimensions. That is, it is\nconfirmed that in two dimensions this transition is second-order, unlike in\nthree dimensions where it is known to be first order. We also estimate the\ncrossover exponent and show that there is a divergent specific heat, finding\n$\\phi=0.7(1)$ or equivalently $\\alpha=0.6(2)$. This is therefore different from\nthe $\\theta$ transition, for which $\\alpha=-1/3$."
    },
    {
        "anchor": "Activity-driven phase transition causes coherent flows of chromatin: We discover a new type of nonequilibrium phase transition in a model of\nchromatin dynamics, which accounts for the coherent motions that have been\nobserved in experiment. The coherent motion is due to the long-range\ncooperation of molecular motors tethered to chromatin. Cooperation occurs if\neach motor acts simultaneously on the polymer and the surrounding solvent,\nexerting on them equal and opposite forces. This drives the flow of solvent\npast the polymer, which in turn affects the orientation of nearby motors and,\nif the drive is strong enough, an active polar (``ferromagnetic'') phase of\nmotors can spontaneously form. Depending on boundary conditions, either\ntransverse flows, or sustained longitudinal oscillations and waves are\npossible. Predicted time and length scales are consistent with experiments. We\nnow have in hand a coarse-grained description of chromatin dynamics which\nreproduces the directed coherent flows of chromatin seen in experiments. This\nfield-theoretic description can be analytically coupled to other features of\nthe nuclear environment such as fluctuating or porous boundaries, local\nheterogeneities in the distribution of chromatin or its activity, leading to\ninsights on the effects of activity on the cell nucleus and its contents.",
        "positive": "Entropy stabilizes floppy crystals of mobile DNA-coated colloids: Grafting linkers with open ends of complementary single-stranded DNA makes a\nflexible tool to tune interactions between colloids,which facilitates the\ndesign of complex self-assembly structures. Recently, it has been proposed to\ncoat colloids with mobile DNA linkers, which alleviates kinetic barriers\nwithout high-density grafting, and also allows the design of valency without\npatches.However, the self-assembly mechanism of this novel system is poorly\nunderstood.Using a combination of theory and simulation, we obtain phase\ndiagrams forthe system in both two and three dimensional spaces, and find\nstable floppy squareand CsCl crystals when the binding strength is strong, even\nin the infinite bindingstrength limit. We demonstrate that these floppy phases\nare stabilized by vibrational entropy, and \"floppy\" modes play an important\nrole in stabilizing the floppy phases for the infinite binding strength limit.\nThis special entropic effect in the self-assembly of mobile DNA-coated colloids\nis very different from conventional molecular self-assembly, and it offers new\naxis to help design novel functional materials using mobile DNA-coated\ncolloids."
    },
    {
        "anchor": "Density dependent speed-up of particle transport in channels: Collective transport through channels shows surprising properties under\none-dimensional confinement: particles in a single file exhibit sub-diffusive\nbehavior, while liquid confinement causes distance-independent correlations\nbetween the particles. Such interactions in channels are well studied for\npassive Brownian motion, but driven transport remains largely unexplored. Here,\nwe demonstrate gating of transport due to a speed-up effect for actively driven\nparticle transport through microfluidic channels. We prove that particle\nvelocity increases with particle density in the channel due to hydrodynamic\ninteractions under electrophoretic and gravitational forces. Numerical models\ndemonstrate that the observed speed-up of transport originates from a\nhydrodynamic piston-like effect. Our discovery is fundamentally important for\nunderstanding protein channels and transport through porous materials and for\ndesigning novel sensors and filters.",
        "positive": "Surface Tension Between Coexisting Phases of Active Brownian Particles: The confliction between the stable interface in phase-separated active\nBrownian particles and its negative surface tension, obtained mechanically via\nthe active pressure, has sparked considerable debate about the formula of\nactive surface tension. Based on the intrinsic pressure of active system, we\nhere derive a proper mechanical expression of active surface tension by\ncalculating the work required to create a differential interface area, while\nremaining interfacial profile invariant (not considered previously). Our\nexpression yields a significantly positive surface tension that increases with\nthe particle actvity, which is supported by mechanical analysis on the\ninterface. Our results thus fundamentally resolve the contradiction related to\nactive surface tension."
    },
    {
        "anchor": "Hydrodynamics of polar liquid crystals: Starting from a microscopic definition of an alignment vector proportional to\nthe polarization, we discuss the hydrodynamics of polar liquid crystals with\nlocal $C_{\\infty v}$-symmetry. The free energy for polar liquid crystals\ndiffers from that of nematic liquid crystals ($D_{\\infty h}$) in that it\ncontains terms violating the ${\\bf{n}}\\to -{\\bf{n}}$ symmetry. First we show\nthat these $\\mathcal{Z}_2$-odd terms induce a general splay instability of a\nuniform polarized state in a range of parameters. Next we use the general\nPoisson-bracket formalism to derive the hydrodynamic equations of the system in\nthe polarized state. The structure of the linear hydrodynamic modes confirms\nthe existence of the splay instability.",
        "positive": "Boundary Curvature Effect on the Wrinkling of Thin Suspended Films: In this letter, we demonstrate a relation between the boundary curvature\n$\\kappa$ and the wrinkle wavelength $\\lambda$ of a thin suspended film under\nboundary confinement. Experiments are done with nanocrystalline diamond films\nof thickness $t \\approx 184$~nm grown on glass substrates. By removing portions\nof the substrate after growth, suspended films with circular boundaries of\nradius $R$ ranging from approximately 30 to 811 $\\mu$m are made. Due to\nresidual stresses, the portions of film attached to the substrate are of\ncompressive prestrain $\\epsilon_0 \\approx 11 \\times 10^{-4}$ and the suspended\nportions of film are azimuthally wrinkled at their boundary. We find that\n$\\lambda$ monotonically decreases with $\\kappa$ and present a model predicting\nthat $\\lambda \\propto t^{1/2}(\\epsilon_0 + \\Delta R \\kappa)^{-1/4}$, where\n$\\Delta R$ denotes a penetration depth over which strain relaxes at a boundary.\nThis relation is in agreement with our experiments and may be adapted to other\nsystems such as plant leaves. Also, we establish a novel method for measuring\nresidual compressive strain in thin films."
    },
    {
        "anchor": "Incorporating multi-body effects in SAFT by improving the description of\n  the reference system. I. Mean activity correction for cluster integrals in\n  the reference system: A system of patchy colloidal particles interacting with a solute that can\nassociate multiple times in any direction is a useful model for patchy\ncolloidal mixtures. Despite the simplicity of the interaction, because of the\npresence of multi-body correlations predicting the thermodynamics of such\nsystems remains a challenge. Earlier Marshall and Chapman developed a\nmulti-body formulation for such systems wherein the cluster partition function\nfor the hard-sphere solvent molecules in a defined inner-shell (or coordination\nvolume) of the hard-sphere solute is used as the reference within the\nstatistical association fluid theory formalism. The multi-body contribution to\nthese partition functions are obtained by ignoring the bulk solvent, thus\nlimiting the applicability of the theory to low system densities. Deriving\ninspiration from the quasichemical theory of solutions where these partition\nfunctions occur in the guise of equilibrium constants for cluster formation, we\ndevelop a way to account for the multi-body correlations including the effect\nof the bulk solvent. We obtain the free energy to evacuate the inner-shell, the\nchemistry contribution within quasichemical theory, from simulations of the\nhard-sphere reference. This chemistry contribution reflects association in the\nreference in the presence of the bulk medium. The gas-phase partition functions\nare then augmented by a mean activity factor that is adjusted to reproduce the\nchemistry contribution. We show that the updated partition function provides a\nrevised reference that better captures the distribution of solvent around the\nsolute up to high system densities. Using this updated reference, we find that\ntheory better describes both the bonding state and the excess chemical\npotential of the colloid in the physical system.",
        "positive": "Mechanism of chain collapse of strongly charged polyelectrolytes: We perform extensive molecular dynamics simulations of a charged polymer in a\ngood solvent in the regime where the chain is collapsed. We analyze the\ndependence of the gyration radius $R_g $ on the reduced Bjerrum length $\\ell_B$\nand find two different regimes. In the first one, called as a weak\nelectrostatic regime, $R_g \\sim \\ell_B^{-1/2}$, which is consistent only with\nthe predictions of the counterion-fluctuation theory. In the second one, called\na strong electrostatic regime, we find $R_g \\sim \\ell_B^{-1/5}$. To explain the\nnovel regime we modify the counterion-fluctuation theory."
    },
    {
        "anchor": "Model for the alpha and beta shear-mechanical properties of supercooled\n  liquids and its comparison to squalane data: This paper presents data for supercooled squalane's frequency-dependent shear\nmodulus covering frequencies from 10 mHz to 30 kHz and temperatures from 168 K\nto 190 K; measurements are also reported for the glass phase down to 146 K. The\ndata reveal a strong mechanical beta process. A model is proposed for the shear\nresponse of supercooled liquids. The model is an electrical equivalent-circuit\ncharacterized by additivity of the dynamic shear compliances of the alpha and\nbeta processes. The nontrivial parts of the alpha and beta processes are\nrepresented by a \"Cole-Cole retardation element\", resulting in the Cole-Cole\ncompliance function well-known from dielectrics. The model, which assumes that\nthe high-frequency decay of the alpha shear compliance loss varies with angular\nfrequency as $\\omega^{-1/2}$, has seven parameters. Assuming time-temperature\nsuperposition for the alpha and the beta processes separately, the number of\nparameters varying with temperature is reduced to four. From the temperature\ndependence of the best-fit model parameters the following conclusions are\ndrawn: 1) the alpha relaxation time conforms to the shoving model; 2) the beta\nrelaxation loss-peak frequency is almost temperature independent; 3) the alpha\ncompliance magnitude, which in the model equals the inverse of the\ninstantaneous shear modulus, is only weakly temperature dependent; 4) the beta\ncompliance magnitude decreases by a factor of three upon cooling in the\ntemperature range studied. The final part of the paper briefly presents\nmeasurements of the dynamic adiabatic bulk modulus covering frequencies from 10\nmHz to 10 kHz in the temperature range 172 K to 200 K. The data are\nqualitatively similar to the shear data by having a significant beta process. A\nsingle-order-parameter framework is suggested to rationalize these\nsimilarities.",
        "positive": "Minimal model of an active solid deviates from equilibrium mechanics: In this work, the mechanical response oF an one-dimensional active solid --\ndefined as a network of active stochastic particles interacting by nonlinear\nhard springs -- subject to an external deformation force, is numerically\nstudied and rationalized with a minimal model. It is found that an active solid\nmade of linear springs and subject to an external stress, presents an average\ndeformation which is independent of the system's activity. However, when the\nactive solid is made of nonlinear hard springs, the solid's average deformation\ndecreases with respect to a passive system under the same conditions, and as a\nfunction of activity and rotational noise in the system. The latter result may\nshed light on new ways to creating an active metamaterial, which could tune its\nstiffness by moving either its activity or rotational noise."
    },
    {
        "anchor": "Plastic deformations in crystal, polycrystal, and glass in binary\n  mixtures under shear: Collective yielding: Using molecular dynamics simulation, we examine the dynamics of crystal,\npolycrystal, and glass in a Lennard-Jones binary mixture composed of small and\nlarge particles in two dimensions. The crossovers occur among these states as\nthe composition c is varied at fixed size ratio. Shear is applied to a system\nof 9000 particles in contact with moving boundary layers composed of 1800\nparticles. The particle configurations are visualized with a sixfold\norientation angle alpha_j(t) and a disorder variable D_j(t) defined for\nparticle j, where the latter represents the deviation from hexagonal order.\nFundamental plastic elements are classified into dislocation gliding and grain\nboundary sliding. At any c, large-scale yielding events occur on the acoustic\ntime scale. Moreover, they multiply occur in narrow fragile areas, forming\nshear bands. The dynamics of plastic flow is highly hierarchical with a wide\nrange of time scales for slow shearing. We also clarify the relationship\nbetween the shear stress averaged in the bulk region and the wall stress\napplied at the boundaries.",
        "positive": "Computer simulations of single particles in external electric fields: Applying electric fields is an attractive way to control and manipulate\nsingle particles or molecules, e.g., in lab-on-a-chip devices. However, the\nresponse of nanosize objects in electrolyte solution to external fields is far\nfrom trivial. It is the result of a variety of dynamical processes taking place\nin the ion cloud surrounding charged particles and in the bulk electrolyte, and\nit is governed by an intricate interplay of electrostatic and hydrodynamic\ninteractions. Already systems composed of one single particle in electrolyte\nsolution exhibit a complex dynamical behaviour. In this review, we discuss\nrecent coarse-grained simulations that have been performed to obtain a\nmolecular-level understanding of the dynamic and dielectric response of single\nparticles and single macromolecules to external electric fields. We address\nboth the response of charged particles to constant fields (DC fields), which\ncan be characterized by an electrophoretic mobility, and the dielectric\nresponse of both uncharged and charged particles to alternating fields (AC\nfields), which is described by a complex polarizability. Furthermore, we give a\nbrief survey of simulation algorithms and highlight some recent developments."
    },
    {
        "anchor": "Arches and contact forces in a granular pile: Assemblies of granular particles mechanically stable under their own weight\ncontain arches. These are structural units identified as sets of mutually\nstable grains. It is generally assumed that these arches shield the weight\nabove them and should bear most of the stress in the system. We test such\nhypothesis by studying the stress born by in-arch and out-of-arch grains. We\nshow that, indeed, particles in arches withstand larger stresses. In\nparticular, the isotropic stress tends to be larger for in-arch-grains whereas\nthe anisotropic component is marginally distinguishable between the two types\nof particles. The contact force distributions demonstrate that an exponential\ntail (compatible with the maximization of entropy under no extra constraints)\nis followed only by the out-of-arch contacts. In-arch contacts seem to be\ncompatible with a Gaussian distribution consistent with a recently introduced\napproach that takes into account constraints imposed by the local force balance\non grains.",
        "positive": "Multi-scale Patterns formed by Sodium Sulphate in a Drying Droplet of\n  Gelatin: We present a study of patterns, formed in drying drops of aqueous gelatin\nsolution containing sodium sulphate. The patterns are highly complex,\nconsisting of a hierarchical sequence of rings which form concentric bands as\nwell as dendritic crystalline aggregates. When the preparation of the complex\nfluid is done by mixing an aqueous solution of the salt with an aqueous\nsolution of gelatin prepared separately, another feature is observed in the\npattern on the dried out drop. This is a viscous fingering pattern, superposed\non the series of rings. We try to explain the origin of these two features from\na simple physical approach."
    },
    {
        "anchor": "The structural origin of the hard-sphere glass transition in granular\n  packing: Glass transition is accompanied by a rapid growth of the structural\nrelaxation time and a concomitant decrease of configurational entropy. It\nremains unclear whether the transition has a thermodynamic origin, and whether\nthe dynamic arrest is associated with the growth of a certain static order.\nUsing granular packing as a model hard-sphere glass, we show the glass\ntransition as a thermodynamic phase transition with a \"hidden\" polytetrahedral\norder. This polytetrahedral order is spatially correlated with the slow\ndynamics. It is geometrically frustrated and has a peculiar fractal dimension.\nAdditionally, as the packing fraction increases, its growth follows an\nentropy-driven nucleation process, similar to that of the random first-order\ntransition theory. Our study essentially identifies a long-sought-after\nstructural glass order in hard-sphere glasses.",
        "positive": "The percolation transition of hydration water: from planar hydrophilic\n  surfaces to proteins: The formation of a spanning hydrogen-bonded network of hydration water is\nfound to occur via a 2D percolation transition in various systems: smooth\nhydrophilic surfaces, the surface of a single protein molecule, protein powder\nand diluted peptide solution. The average number of water-water hydrogen bonds\nnH at the percolation threshold varies from 2.0 to 2.3, depending on\ntemperature, system size and surface properties. Calculation of nH allows an\neasy estimation of the percolation threshold of hydration water in various\nsystems, including biomolecules."
    },
    {
        "anchor": "Uniform distortions and generalized elasticity of liquid crystals: Ordinary nematic liquid crystals are characterized by having a uniform\ndirector field as ground state. In such a state, the director is the same\neverywhere and no distortion is to be seen at all. We give a definition of\nuniform distortion which makes precise the intuitive notion of seeing\neverywhere the same director landscape. We characterize all such distortions\nand prove that they fall into two families, each described by two scalar\nparameters. Uniform distortions exhaust R. Meyer's heliconical structures,\nwhich, as it has recently been recognized, include the ground state of\ntwist-bend nematics. The generalized elasticity of these new phases is treated\nwith a simple free-energy density, which can be minimized by both uniform and\nnon-uniform distortions, the latter injecting a germ of elastic frustration.",
        "positive": "Leak-rate of seals: effective medium theory and comparison with\n  experiment: Seals are extremely useful devices to prevent fluid leakage. We present an\neffective medium theory of the leak-rate of rubber seals, which is based on a\nrecently developed contact mechanics theory. We compare the theory with\nexperimental results for seals consisting of silicon rubber in contact with\nsandpaper and sand-blasted PMMA surfaces."
    },
    {
        "anchor": "Water/Cosolvent Attraction Induced Phase Separation: a Molecular Picture\n  of Cononsolvency: Cononsolvency is a phenomenon for which the solubility of a macromolecule\ndecreases or even vanishes in the mixture of two good solvents. Although it has\nbeen widely applied in physicochemical, green chemical and pharmaceutical\nindustry, its origin is still under active debate. Here, by using combined\nneutron total scattering, deuterium-labelling and all-atom molecular dynamic\nsimulations, we demonstrated that it is the strong water/cosolvent attraction\nthat leads to the cononsolvency. The combined approach presented here has\nopened a new route for investigating the most probable all-atom structure in\nmacromolecular solutions and the thermodynamic origin of solubilities.",
        "positive": "The elasto-/hydro-dynamics of quasicrystals with 12- and 18-fold\n  symmetries in some soft matters and mathematical solutions: The observation recently of 12-fold quasicrystals in polymers, nanoparticle\nmixture and 12-fold and 18-fold quasicrystals in colloidal solutions are\nimportant events for the study of quasicrystals. To describe the mechanical\nbehaviour we propose a new solid-liquid phase quasicrystal model for some soft\nmatters including polymers and colloids. The so-called new solid-liquid phase,\nis a new phase model of anisotropic fluid, but different from liquid crystal\nphase, here the structure presents quasiperiodic symmetry. Based on the model,\nthe elasticity, fluidity and viscosity of the material have been studied, the\nrelevant mathematical theory has also been proposed. Some mathematical\nsolutions of the theory are discussed."
    },
    {
        "anchor": "How to mesh up Ewald sums (I): A theoretical and numerical comparison of\n  various particle mesh routines: Standard Ewald sums, which calculate e.g. the electrostatic energy or the\nforce in periodically closed systems of charged particles, can be efficiently\nspeeded up by the use of the Fast Fourier Transformation (FFT). In this article\nwe investigate three algorithms for the FFT-accelerated Ewald sum, which\nattracted a widespread attention, namely, the so-called\nparticle-particle-particle-mesh (P3M), particle mesh Ewald (PME) and smooth PME\nmethod. We present a unified view of the underlying techniques and the various\ningredients which comprise those routines. Additionally, we offer detailed\naccuracy measurements, which shed some light on the influence of several tuning\nparameters and also show that the existing methods -- although similar in\nspirit -- exhibit remarkable differences in accuracy. We propose combinations\nof the individual components, mostly relying on the P3M approach, which we\nregard as most flexible.",
        "positive": "Morphology of residually-stressed tubular tissues: Beyond the elastic\n  multiplicative decomposition: Many interesting shapes appearing in the biological world are formed by the\nonset of mechanical instability. In this work we consider how the build-up of\nresidual stress can cause a solid to buckle. In all past studies a fictitious\n(virtual) stress-free state was required to calculate the residual stress. In\ncontrast, we use a model which is simple and allows the prescription of any\nresidual stress field.\n  We specialize the analysis to an elastic tube subject to a two-dimensional\nresidual stress, and find that incremental wrinkles can appear on its inner or\nits outer face, depending on the location of the highest value of the residual\nhoop stress. We further validate the predictions of the incremental theory with\nfinite element simulations, which allow us to go beyond this threshold and\npredict the shape, number and amplitude of the resulting creases."
    },
    {
        "anchor": "Torsional oscillator studies of the superfluidity of 3He in aerogel: We have made simultaneous torsional oscillator and transverse NMR\nmeasurements (at 165 kHz) on 3He contained within aerogels with nominal\ndensities of 1% and 2% of solid glass. The superfluid transition is seen\nsimultaneously by both techniques and occurs at a temperature which agrees\nsemi-quantitatively with that expected for homogeneous isotropic pair-breaking\nscattering of 3He atoms by strands of silica. Values obtained for the\nsuperfluid density rho_s in the 2% sample are in reasonable agreement with\nthose observed previously. Coupling of the torsional mode to a parasitic\nresonance prevented accurate determination of rho_s for the 1% aerogel. We have\nidentified other resonances coupling to the torsional oscillations as sound\nmodes within the helium/aerogel medium.",
        "positive": "Binding of curvature-inducing proteins onto tethered vesicles: A tethered vesicle, which consists of a cylindrical membrane tube and a\nspherical vesicle, is produced by a mechanical force that is experimentally\nimposed by optical tweezers and a micropipette. This tethered vesicle is\nemployed for examining the curvature sensing of curvature-inducing proteins. In\nthis study, we clarify how the binding of proteins with a laterally isotropic\nspontaneous curvature senses and generates the membrane curvatures of the\ntethered vesicle using mean-field theory and meshless membrane simulation. The\nforce-dependence curves of the protein density in the membrane tube and the\ntube curvature are reflection symmetric and point symmetric, respectively, from\nthe force point, in which the tube has a sensing curvature. The bending\nrigidity and spontaneous curvature of the bound proteins can be estimated from\nthese force-dependence curves. First-order transitions can occur between low\nand high protein densities in the tube at both low and high force amplitudes.\nThe simulation results of the homogeneous phases agree very well with the\ntheoretical predictions. In addition, beaded-necklace-like tubes with\nmicrophase separation are found in the simulation."
    },
    {
        "anchor": "Pinch-off of bubbles in a polymer solution: The formation of gas bubbles in a liquid occurs in various engineering\nprocesses, such as during foam generation or agitation and mixing in bubbly\nflows. A challenge in describing the initial formation of a gas bubble is due\nto the singular behavior at pinch-off. Past experiments in Newtonian fluids\nhave shown that the minimum neck radius follows a power-law evolution shortly\nbefore the break-up. The exponent of the power-law depends on the viscosity of\nthe surrounding Newtonian liquid, and ranges from 0.5 for low viscosity to 1\nfor large viscosity. However, bubble formation in a viscoelastic polymer\nsolution remains unclear, and in particular, if the evolution is still captured\nby a power-law and how the exponent varies with the polymer concentration. In\nthis study, we use high-speed imaging to analyze the bubble pinch-off in\nsolutions of polymers. We characterize the time evolution of the neck radius\nwhen varying the concentration and thus the characteristic relaxation time and\ndescribe the influence of viscoelasticity on the bubble pinch-off. Our results\nreveal that the presence of polymers does not influence the thinning until the\nlatter stages, when their presence in sufficient concentration delays the\npinch-off.",
        "positive": "Phase diagram of Janus Particles: We deeply investigate a simple model representative of the recently\nsynthesized Janus particles, i.e. colloidal spherical particles whose surface\nis divided into two areas of different chemical composition. When the two\nsurfaces are solvophilic and solvophobic, these particles constitute the\nsimplest example of surfactants. The phase diagram includes a colloidal-poor\n(gas) colloidal-rich (liquid) de-mixing region, which is progressively\nsuppressed by the insurgence of micelles, providing the first model where\nmicellization and phase-separation are simultaneously observed. The coexistence\ncurve is found to be negatively sloped in the temperature-pressure plane,\nsuggesting that Janus particles can provide a colloidal system with anomalous\nthermodynamic behavior."
    },
    {
        "anchor": "Modelling microgels with controlled structure across the volume phase\n  transition: Thermoresponsive microgels are soft colloids that find widespread use as\nmodel systems for soft matter physics. Their complex internal architecture,\nmade of a disordered and heterogeneous polymer network, has been so far a major\nchallenge for computer simulations. In this work we put forward a\ncoarse-grained model of microgels whose structural properties are in\nquantitative agreement with results obtained with small-angle X-ray scattering\nexperiments across a wide range of temperatures, encompassing the volume phase\ntransition. These results bridge the gap between experiments and simulations of\nindividual microgel particles, paving the way to theoretically address open\nquestions about their bulk properties with unprecedented nano and microscale\nresolution.",
        "positive": "Elastomeric Nematic Colloids, Colloidal Crystals and Microstructures\n  with Complex Topology: Control of physical behaviors of nematic colloids and colloidal crystals has\nbeen demonstrated by tuning particle shape, topology, chirality and surface\ncharging. However, the capability of altering physical behaviors of such soft\nmatter systems by changing particle shape and the ensuing responses to external\nstimuli has remained elusive. We fabricated genus-one nematic elastomeric\ncolloidal ring-shaped particles and various microstructures using two-photon\nphotopolymerization. Nematic ordering within both the nano-printed particle and\nthe surrounding medium leads to anisotropic responses and actuation when\nheated. With the thermal control, elastomeric microstructures are capable of\nchanging from genus-one to genus-zero surface topology. Using these particles\nas building blocks, we investigated elastomeric colloidal crystals immersed\nwithin a liquid crystal fluid, which exhibit crystallographic symmetry\ntransformations. Our findings may lead to colloidal crystals responsive to a\nlarge variety of external stimuli, including electric fields and light.\nPre-designed response of elastomeric nematic colloids, including changes of\ncolloidal surface topology and lattice symmetry, are of interest for both\nfundamental research and applications."
    },
    {
        "anchor": "Sub-ms dynamics of the instability onset of electrospinning: Electrospun polymer jets are imaged for the first time at an ultra-high rate\nof 10,000 frames per second, investigating the process dynamics, and the\ninstability propagation velocity and displacement in space. The polymer\nconcentration, applied voltage bias and needle-collector distance are\nsystematically varied, and their influence on the instability propagation\nvelocity and on the jet angular fluctuations analyzed. This allows us to unveil\nthe instability formation and cycling behavior, and its exponential growth at\nthe onset, exhibiting radial growth rates of the order of 10^3 s^-1. Allowing\nthe conformation and evolution of polymeric solutions to be studied in depth,\nhigh-speed imaging at sub-ms scale shows a significant potential for improving\nthe fundamental knowledge of electrified jets, leading to obtain finely\ncontrollable bending and solution stretching in electrospinning, and\nconsequently better designed nanofibers morphologies and structures.",
        "positive": "Singular instability of exact stationary solutions of the nonlocal\n  Gross-Pitaevskii equation: In this paper we show numerically that for nonlinear Schrodinger type systems\nthe presence of nonlocal perturbations can lead to a beyond-all-orders\ninstability of stable solutions of the local equation. For the specific case of\nthe nonlocal one-dimensional Gross-Pitaevskii equation with an external\nstanding light wave potential, we construct exact stationary solutions for an\narbitrary interaction kernel. As the nonlocal and local equations approach each\nother (by letting an appropriate small parameter $\\epsilon\\to 0$), we compare\nthe dynamics of the respective solutions. By considering the time of onset of\ninstability, the singular nature of the inclusion of nonlocality is\ndemonstrated, independent of the form of the interaction kernel."
    },
    {
        "anchor": "Theoretical and experimental study of the orientational ordering in the\n  field-induced intermediaite phase from the SmC*FI2 phase in chiral smectic\n  liquid crystals: Under an electric field, chiral smectic liquid crystals transit usually to\nthe unwound SmC* phase where the helical structure is completely unrolled.\nSometimes the sample transits initially towards an intermediate polar state\nbefore the total destruction of the helix. Based on the extension of the H-T\nmodel, a theoretical study of these field-induced phase transitions was carried\nout. Two hypotheses of the dynamics that give rise to the appearance of the\nintermediate phase have been discussed. The results of a numerical analysis\nconfirm the known experimental results; the intermediate phase has a\nthree-layer periodicity structure.",
        "positive": "A Single-Input State-Switching Building Block Harnessing Internal\n  Instabilities: Bistable mechanisms are prevalent across a broad spectrum of applications due\nto their ability to maintain two distinct stable states. Their energy\nconsumption is predominantly confined to the process of state transitions,\nthereby enhancing their efficiency. However, the transition often requires two\ndistinct inputs, implicating the requirement of multiple actuators. Here, we\npropose an elastic and contactless design strategy for inducing state\ntransitions in bistable mechanisms, requiring only a single cyclic input. The\nstrategy leverages internal information, interpreted as system state, as an\nextra input to make a weighted decision for transitioning to the subsequent\nstate. We characterize the behavior using a spring-based rigid-body model,\nconsisting of a column near bifurcation, combined with a non-linear spring\nconnected to a bistable element that represents the information state. The\nresults show that a nonlinear spring with a quadratic stiffness function, i.e.,\nrepresenting internal instability, is crucial for regulating state-switching\nbehavior. We then demonstrate this design strategy by developing a monolithic\nand compliant design embodiment and experimentally evaluate its behavior."
    },
    {
        "anchor": "Validity of Stokes-Einstein Relation in Soft Colloids up to the Glass\n  Transition: We investigate the dynamics of kinetically frozen block copolymer micelles of\ndifferent softness across a wide range of particle concentrations, from the\nfluid to the onset of glassy behavior, through a combination of rheology,\ndynamic light scattering and pulsed field gradient NMR spectroscopy. We\nadditionally perform Brownian dynamics simulations based on an ultrasoft\ncoarse-grained potential, which are found to be in quantitative agreement with\nexperiments, capturing even the very details of dynamic structure factors S(Q,\nt) on approaching the glass transition. We provide evidence that for these\nsystems the Stokes-Einstein relation holds up to the glass transition; given\nthat it is violated for dense suspensions of hard colloids, our findings\nsuggest that its validity is an intriguing signature of ultrasoft interactions.",
        "positive": "Similarities between GSH, Hypoplasticity and KCR: Accounting for elasto-plastic motion in granular media, hypoplasticity is a\nstate-of-the-art constitutive model derived from data accumulated over many\ndecades. In contrast, GSH, a hydrodynamic theory, is derived from general\nprinciples of physics, with comparatively few inputs from experiments, yet\nsporting an applicability ranging from static stress distribution via\nelasto-plastic motion to fast dense flow, including non-uniform ones such as a\nshear band. Comparing both theories, we find great similarities for uniform,\nslow, elasto-plastic motion. We also find that proportional paths and the\nGoldscheider rule used to construct barodesy, another, more recent constitutive\nmodel, are natural results of GSH's equations. This is useful as it gives these\nconstitutive relations a solid foundation in physics, and in reverse, GSH a\nrobust connection to reality. The same symbiotic relation exists between GSH\nand KCR, or Kamrin's non-local constitutive relation, a model that was\nsuccessfully employed to account for a wide shear band in split bottom cells."
    },
    {
        "anchor": "The response of a macromolecule near a tiled substrate: We analyze response of a macromolecule near to a substrate; the substrate is\ntiled in the sequential and specific manner so that repeat units of the\nmacromolecule may have different response on its adsorption in different\ndirections onto the substrate. The lattice model of random walk has been used\nto analyze the adsorption-desorption behavior of an infinitely long\nhomo-polymer molecule on a sequentially tiled substrate in three dimensions.\nThe lattice model for the Gaussian chain and directed self-avoiding chain has\nbeen solved analytically. It has been emphasized on the basis of analytical\nestimates that a suitable coating may modify affinity of the macromolecule on\nthe living surfaces and on the non living substrates in the complex manner\nwhich may be suitable means to control growth and also a route to restrict the\nspread of the deadly microbes.",
        "positive": "On the effective charge of hydrophobic polyelectrolytes: In this paper we analyze the behavior of hydrophobic polyelectrolytes. It has\nbeen proposed that this system adopts a pearl-necklace structure reminiscent of\nthe Rayleigh instability of a charged droplet. Using a Poisson-Boltzmann\napproach, we calculate the counterion distribution around a given pearl\nassuming the latter to be penetrable for the counterions. This allows us to\ncalculate the effective electric charge of the pearl as a function of the\nchemical charge. Our predictions are in very good agreement with the recent\nexperimental measurements of the effective charge by Essafi et al. (Europhys.\nLett. 71, 938 (2005)). Our results allow to understand the large deviation from\nthe Manning law observed in these experiments."
    },
    {
        "anchor": "Stability of Granular Tunnel: We demonstrated the stability of tunnels made of granular matters is strongly\ndependent on the grain size, tunnel diameter, and water content in the\ngranules. Larger tunnel radius, larger grain size, and too much water content\ntend to destabilize the tunnel. We also develop a model to describe such\nfindings. We identified a phase diagram of stability which greatly controlled\nby granular bond order. For granular bond order of larger than unity, we can\nalways made a stable tunnel. However, for granular bond order of less than\nunity, we obtain a general expression for maximum tunnel thickness that can be\nmade. To best of our knowledge, this is the first exploration regarding the\ngranular tunnel stability.",
        "positive": "Synchronisation and liquid crystalline order in soft active fluids: We introduce a phenomenological theory for a new class of soft active fluids,\nwith the ability to synchronise. Our theoretical framework describes the\nmacroscopic behaviour of a collection of interacting anisotropic elements with\ncyclic internal dynamics and a periodic phase variable. This system (i) can\nspontaneously undergo a transition to a state with macroscopic orientational\norder, with the elements aligned: a liquid crystal, (ii) attain another broken\nsymmetry state characterised by synchronisation of their phase variables or\n(iii) a combination of both types of order. We derive the equations describing\na spatially homogeneous system and also study the hydrodynamic fluctuations of\nthe soft modes in some of the ordered states. We find that synchronisation can\npromote the transition to a state with orientational order; and vice-versa.\nFinally, we provide an explicit microscopic realisation: a suspension of\nmicro-swimmers driven by cyclic strokes."
    },
    {
        "anchor": "External and intrinsic anchoring in nematic liquid crystals: A Monte\n  Carlo study: We present a Monte Carlo study of external surface anchoring in nematic cells\nwith partially disordered solid substrates, as well as of intrinsic anchoring\nat free nematic interfaces. The simulations are based on the simple hexagonal\nlattice model with a spatially anisotropic intermolecular potential. We\nestimate the corresponding extrapolation length $b$ by imposing an elastic\ndeformation in a hybrid cell-like nematic sample. Our estimates for $b$\nincrease with increasing surface disorder and are essentially\ntemperature--independent. Experimental values of $b$ are approached only when\nboth the coupling of nematic molecules with the substrate and the anisotropy of\nnematic--nematic interactions are weak.",
        "positive": "The range and nature of effective interactions in hard-sphere solids: Colloidal systems observed in video microscopy are often analysed using the\ndisplacements correlation matrix of particle positions. In non-thermal systems,\nthe inverse of this matrix can be interpreted as a pair-interaction potential\nbetween particles. If the system is thermally agitated, however, only an\neffective interaction is accessible from the correlation matrix. We show how\nthis effective interaction differs from the non-thermal case by comparing with\nhigh-statistics numerical data from hard-sphere crystals."
    },
    {
        "anchor": "Metric mechanics with non-trivial topology: actuating irises, cylinders\n  and evertors: Liquid crystal elastomers contract along their director on heating and\nrecover on cooling, offering great potential as actuators and artificial\nmuscles. If a flat sheet is programmed with a spatially varying director\npattern, it will actuate into a curved surface, allowing the material to act as\na strong machine such as a grabber or lifter. Here we study the actuation of\nprogrammed annular sheets which, owing to their central hole, can sidestep\nconstraints on area and orientation. We systematically catalogue the set of\ndevelopable surfaces encodable via axisymmetric director patterns, and uncover\nseveral qualitatively new modes of actuation, including cylinders, irises, and\neverted surfaces in which the inner boundary becomes the outer boundary after\nactuation. We confirm our designs with a combination of experiments and\nnumerics. Many of our actuators can re-attain their initial inner or outer\nradius upon completing actuation, making them particularly promising, as they\ncan avoid potentially problematic stresses in their activated state even when\nfixed onto a frame or pipe.",
        "positive": "Role of particles size on the cohesive strength of non-sintered (green)\n  ceramics: Preparation of particle-loaded foams, followed by drying, sintering and/or\ncross-linking are widely explored routes for developing lightweight ceramics\nwith high mechanical strength. The non-sintered dry ceramic foams are less\nstudied due to their intricate production and the assumed poor mechanical\nstrength of the obtained \"green\" materials. Here we produce lightweight\nceramics from foamed particle suspensions containing spherical silica particles\nwith radii varied between 4.5 nm and 7 {\\mu}m. The wet foams were prepared in\nthe presence of cationic surfactant and were dried at ambient conditions to\nobtain porous materials with mass densities between 100 and 700 kg/m3. The\nmaterials containing smaller particles exhibited much higher strength (up to\n2000 times), approaching that of the sintered materials. A new theoretical\nexpression for predicting the mechanical strength of such materials was derived\nand was used to explain the measured strengths of the produced materials\nthrough the van der Waals attractions between the particles in the final dry\nmaterials."
    },
    {
        "anchor": "Stretching semiflexible filaments with quenched disorder: We study the effect of quenched randomness in the arc-length dependent\nspontaneous curvature of a wormlike chain under tension. In the weakly bending\napproximation in two dimensions, we obtain analytic results for the\nforce-elongation curve and the width of transverse fluctuations. We compare\nquenched and annealed disorder and conclude that the former cannot always be\nreduced to a simple change in the stiffness of the pure system. We also discuss\nthe effect of a random transverse force on the stretching response of a\nwormlike chain without spontaneous curvature.",
        "positive": "Electrohydrodynamics of deflated vesicles: budding, rheology and\n  pairwise interactions: The electrohydrodynamics of vesicle suspensions is characterized by studying\ntheir pairwise interactions in applied DC electric fields in two dimensions. In\nthe dilute limit, the rheology of the suspension is shown to vary nonlinearly\nwith the electric conductivity ratio of the interior and exterior fluids. The\nprolate-oblate-prolate transition and other transitionary dynamics observed in\nexperiments and previously confirmed via numerical simulations is further\ninvestigated here for smaller reduced areas. When two vesicles are initially\nun-aligned with the external electric field, three different responses are\nobserved when the key parameters are varied: (i) chain formation--they\nself-assemble to form a chain that is aligned along the field direction, (ii)\ncirculatory motion--they rotate about each other, (iii) oscillatory\nmotion--they form a chain but oscillate about each other."
    },
    {
        "anchor": "Estimate of the Cutoff Errors in the Ewald Summation for Dipolar Systems: Theoretical estimates for the cutoff errors in the Ewald summation method for\ndipolar systems are derived. Absolute errors in the total energy, forces and\ntorques, both for the real and reciprocal space parts, are considered. The\napplicability of the estimates is tested and confirmed in several numerical\nexamples. We demonstrate that these estimates can be used easily in determining\nthe optimal parameters of the dipolar Ewald summation in the sense that they\nminimize the computation time for a predefined, user set, accuracy.",
        "positive": "Local control for the collective dynamics of self-propelled particles: Utilizing a paradigmatic model for the motion of interacting self-propelled\nparticles, we demonstrate that local accelerations at the level of individual\nparticles can drive transitions between different collective dynamics, leading\nto a control process. We find that the ability to trigger such transitions is\nhierarchically distributed among the particles and can form distinctive spatial\npatterns within the collective. Chaotic dynamics occur during the transitions,\nwhich can be attributed to fractal basin boundaries mediating the control\nprocess. The particle hierarchies described in this study offer decentralized\ncapabilities for controlling artificial swarms."
    },
    {
        "anchor": "Jamming Mechanisms and Density Dependence in a Kinetically-Constrained\n  Model: We add relaxation mechanisms that mimic the effect of temperature and\nnon-equilibrium driving to the recently-proposed spiral model which jams at a\ncritical density rho_c < 1. This enables us to explore unjamming by temperature\nor driving at rho_c < rho < 1. We numerically calculate the relaxation time of\nthe persistence function and its spatial heterogeneity. We disentangle the\nthree different relaxation mechanisms responsible for unjamming when varying\ndensity, temperature, and driving strength, respectively. We show that the\nspatial scale of dynamic heterogeneity depends on density much more strongly\nthan on temperature and driving.",
        "positive": "Autonomous Engulfment of Active Colloids by Giant Lipid Vesicles: The ability to design artificial micro/nanomachines able to perform\nsophisticated tasks crucially depends on the understanding of their interaction\nwith biosystems and their compatibility with the biological environment. Here,\nJanus colloids fuelled only by glucose and light were designed, which can\nautonomously interact with cell-like compartments and trigger endocytosis. The\ncrucial role played by the far field hydrodynamic interaction arising from the\npuller/pusher swimming mode and adhesion is evidenced. It is shown that a large\ncontact time between the active particle and the lipid membrane is required to\nobserve the engulfment of a particle inside a floppy giant lipid vesicle.\nActive Janus colloids showing relatively small velocities and a puller type\nswimming mode are able to target giant vesicles, deform their membranes and\nsubsequently get stably engulfed. An instability arising from the unbound\nmembrane segment is responsible for the transition between partial and complete\nstable engulfment. These experiments shed light on the physical criteria\nrequired for autonomous active particle engulfment in giant vesicles, which can\nserve as general principles in disciplines ranging from drug delivery and\nmicrobial infection to nanomedecine."
    },
    {
        "anchor": "Critical behaviour in the nonlinear elastic response of hydrogels: In this paper we study the elastic response of synthetic hydrogels to an\napplied shear stress. The hydrogels studied here have previously been shown to\nmimic the behaviour of biopolymer networks when they are sufficiently far above\nthe gel point. We show that near the gel point they exhibit an elastic response\nthat is consistent with the predicted critical behaviour of networks near or\nbelow the isostatic point of marginal stability. This point separates rigid and\nfloppy states, distinguished by the presence or absence of finite linear\nelastic moduli. Recent theoretical work has also focused on the response of\nsuch networks to finite or large deformations, both near and below the\nisostatic point. Despite this interest, experimental evidence for the existence\nof criticality in such networks has been lacking. Using computer simulations,\nwe identify critical signatures in the mechanical response of sub-isostatic\nnetworks as a function of applied shear stress. We also present experimental\nevidence consistent with these predictions. Furthermore, our results show the\nexistence of two distinct critical regimes, one of which arises from the\nnonlinear stretch response of semi-flexible polymers..",
        "positive": "Profiling a soft solid layer to passively control the conduit shape in a\n  compliant microchannel during flow: The shape of a microchannel during flow through it is instrumental to\nunderstanding the physics that govern various phenomena ranging from\nrheological measurements of fluids to separation of particles and cells. Two\ncommonly used approaches for obtaining a desired channel shape (for a given\napplication) are (i) fabricating the microchannel in the requisite shape and\n(ii) actuating the microchannel walls during flow to obtain the requisite\nshape. However, these approaches are not always viable. We propose an\nalternative, passive approach to {\\it a priori} tune the elastohydrodynamics in\na microsystem, towards achieving a pre-determined (but not pre-fabricated) flow\ngeometry when the microchannel is subjected to flow. That is to say, we use the\ninteraction between a soft solid layer, the viscous flow beneath it and the\nshaped rigid wall above it, to tune the fluid domain's shape. Specifically, we\nstudy a parallel-wall microchannel whose top wall is a slender soft coating of\narbitrary thickness attached to a rigid platform. We derive a nonlinear\ndifferential equation for the soft coating's fluid--solid interface, which we\nuse to infer how to achieve specific conduit shapes during flow. Using this\ntheory, we demonstrate the tuning of four categories of microchannel\ngeometries, which establishes, via a proof-of-concept, the viability of our\nmodeling framework. We also explore slip length patterning on the rigid bottom\nwall of the microchannel, a common technique in microfluidics, as an addition\n`handle' for microchannel shape control. However, we show that this effect is\nmuch weaker in practice."
    },
    {
        "anchor": "A van der Waals density functional study of adenine on graphite: Single\n  molecular adsorption and overlayer binding: The adsorption of an adenine molecule on graphene is studied using a\nfirst-principles van der Waals functional (vdW-DF) [Dion et al., Phys. Rev.\nLett. 92, 246401 (2004)]. The cohesive energy of an ordered adenine overlayer\nis also estimated. For the adsorption of a single molecule, we determine the\noptimal binding configuration and adsorption energy by translating and rotating\nthe molecule. The adsorption energy for a single molecule of adenine is found\nto be 711 meV, which is close to the calculated adsorption energy of the\nsimilar-sized naphthalene. Based on the single molecular binding configuration,\nwe estimate the cohesive energy of a two-dimensional ordered overlayer. We find\na significantly stronger binding energy for the ordered overlayer than for\nsingle-molecule adsorption.",
        "positive": "Petascale Brownian dynamics simulations of highly resolved polymer\n  chains with hydrodynamic interactions using modern GPUs: Brownian dynamics simulations of fairly long, highly detailed polymer chains,\nat the resolution of a single Kuhn step, remains computationally prohibitive\neven on the modern processors. This is especially true when the beads on the\nchain experience hydrodynamic interactions (HI), which requires the usage of\nmethods like Cholesky decomposition of large matrices at every timestep. In\nthis study, we perform Petascale BD simulations, with HI, of fairly long and\nhighly resolved polymer chains on modern GPUs. Our results clearly highlight\nthe inadequacies of the typical models that use beads connected by springs. In\nthis manuscript, firstly, we present the details of a highly scalable, parallel\nhybrid code implemented on a GPU for BD simulations of chains resolved to a\nsingle Kuhn step. In this hybrid code using CUDA and MPI, we have incorporated\nHI using the Cholesky decomposition method. Next, we validate the GPU\nimplementation extensively with theoretical expectations for polymer chains at\nequilibrium and in flow with results in the absence of HI. Further, our results\nin flow with HI show significantly different temporal variations of stretch, in\nboth startup extensional and shear flows, relative to the conventional\nbead-spring models. In all cases investigated, the ensemble averaged chain\nstretch is much lower than bead-spring predictions. Also, quite remarkably, our\nGPU implementation shows a scaling of $\\sim$$N^{1.2}$ and $\\sim$$N^{2.2}$ of\nthe computational times for shorter and longer chains in the most modern\navailable GPU, respectively, which is significantly lower than the\ntheoretically expected $\\sim$$N^{3}$. We expect our methods and results to pave\nthe way for further analysis of polymer physics in flow fields, with long and\nhighly detailed chain models."
    },
    {
        "anchor": "Comment on the Theory of the Stretching Experiments of RNA in Water: Is is argued that the stretching experiments done on RNA in water can be\ndescribed as a reversible process by Classical Thermodynamics.",
        "positive": "Entry effects of droplet in a micro confinement: implications for\n  deformation-based CTC microfiltration: Deformation based circulating tumor cell (CTC) microchips are a\nrepresentative diagnostic device for early cancer detection. This type of\ndevice usually involves a process of CTC trapping in a confined microgeometry.\nFurther understanding of the CTC flow regime, as well as the threshold\npassing-through pressure is key to the design of deformation based CTC\nfiltration devices. In the present numerical study, we investigate the\ntransitional deformation and pressure signature from surface tension dominated\nflow to viscous shear stress dominated flow using a droplet model. Regarding\nwhether CTC fully blocks the channel inlet, we observe two flow regimes: CTC\nsqueezing and shearing regime. By studying the relation of CTC deformation at\nthe exact critical pressure point for increasing inlet velocity, three\ndifferent types of cell deformation are observed: 1) hemispherical front, 2)\nparabolic front, and 3) elongated CTC co-flowing with carrier media. Focusing\non the circular channel, we observe a first increasing and then decreasing\ncritical pressure change with increasing flow rate. By pressure analysis, the\nconcept of optimum velocity is proposed to explain the behavior of CTC\nfiltration and design optimization of CTC filter. Similar behavior is also\nobserved in channels with symmetrical cross sessions like square and triangular\nbut not in rectangular channels which only results in decreasing critical\npressure."
    },
    {
        "anchor": "On the Packing of Stiff Rods on Ellipsoids Part I -- Geometry: We suggest a geometrical mechanism for the ordering of slender filaments\ninside non-isotropic containers, using cortical microtubules in plant cells and\npacking of viral genetic material inside capsids as concrete examples. We show\nanalytically how the shape of the cell affects the ordering of phantom,\nnon-self-avoiding, stiff rods. We find that for oblate cells the preferred\norientation is along the equator, while for prolate spheroids with an aspect\nratio close to one, the orientation is along the principal (long axis).\nSurprisingly, at high enough aspect ratio, a configurational phase transition\noccurs, and the rods no longer point along the principal axis, but at an angle\nto it, due to high curvature at the poles. We discuss some of the possible\neffects of self avoidance, using energy considerations. These results are\nrelevant to other packing problems as well, such as spooling of filament in the\nindustry or spider silk inside water droplets.",
        "positive": "A molecular dynamics study on the equilibrium magnetization properties\n  and structure of ferrofluids: We investigate in detail the initial susceptibility, magnetization curves,\nand microstructure of ferrofluids in various concentration and particle dipole\nmoment ranges by means of molecular dynamics simulations. We use the Ewald\nsummation for the long-range dipolar interactions, take explicitly into account\nthe translational and rotational degrees of freedom, coupled to a Langevin\nthermostat. When the dipolar interaction energy is comparable with the thermal\nenergy, the simulation results on the magnetization properties agree with the\ntheoretical predictions very well. For stronger dipolar couplings, however, we\nfind systematic deviations from the theoretical curves. We analyze in detail\nthe observed microstructure of the fluids under different conditions. The\nformation of clusters is found to enhance the magnetization at weak fields and\nthus leads to a larger initial susceptibility. The influence of the particle\naggregation is isolated by studying ferro-solids, which consist of magnetic\ndipoles frozen in at random locations but which are free to rotate. Due to the\nartificial suppression of clusters in ferro-solids the observed susceptibility\nis considerably lowered when compared to ferrofluids."
    },
    {
        "anchor": "Lattice Boltzmann simulations of anisotropic particles at liquid\n  interfaces: Complex colloidal fluids, such as emulsions stabilized by complex shaped\nparticles, play an important role in many industrial applications. However,\nunderstanding their physics requires a study at sufficiently large length\nscales while still resolving the microscopic structure of a large number of\nparticles and of the local hydrodynamics. Due to its high degree of locality,\nthe lattice Boltzmann method, when combined with a molecular dynamics solver\nand parallelized on modern supercomputers, provides a tool that allows such\nstudies. Still, running simulations on hundreds of thousands of cores is not\ntrivial. We report on our practical experiences when employing large fractions\nof an IBM Blue Gene/P system for our simulations. Then, we extend our model for\nspherical particles in multicomponent flows to anisotropic ellipsoidal objects\nrendering the shape of e.g. clay particles. The model is applied to a number of\ntest cases including the adsorption of single particles at fluid interfaces and\nthe formation and stabilization of Pickering emulsions or bijels.",
        "positive": "Topological complexity, contact order and protein folding rates: Monte Carlo simulations of protein folding show the emergence of a strong\ncorrelation between the relative contact order parameter, CO, and the folding\ntime, t, of two-state folding proteins for longer chains with number of amino\nacids, N>=54, and higher contact order, CO > 0.17. The correlation is\nparticularly strong for N=80 corresponding to slow and more complex folding\nkinetics. These results are qualitatively compatible with experimental data\nwhere a general trend towards increasing t with CO is indeed observed in a set\nof proteins with chain length ranging from 41 to 154 amino acids."
    },
    {
        "anchor": "Disentangling $\u03b1$ and $\u03b2$ relaxation in orientationally\n  disordered crystals with theory and experiments: We use a microscopically motivated Generalized Langevin Equation (GLE)\napproach to link the vibrational density of states (VDOS) to the dielectric\nresponse of orientational glasses (OGs). The dielectric function calculated\nbased on the GLE is compared with experimental data for the paradigmatic case\nof two OGs: Freon 112 and Freon 113, around and just above $T_g$. The memory\nfunction is related to the integral of the VDOS times a spectral coupling\nfunction $\\gamma(\\omega_p)$, which tells the degree of dynamical coupling\nbetween molecular degrees of freedom at different eigenfrequencies. The\ncomparative analysis of the two Freons reveals that the appearance of a\nsecondary $\\beta$ relaxation in Freon 112 is due to cooperative dynamical\ncoupling in the regime of mesoscopic motions caused by stronger anharmonicity\n(absent in Freon 113), and is associated with comparatively lower boson peak in\nthe VDOS. The proposed framework brings together all the key aspects of glassy\nphysics (VDOS with boson peak, dynamical heterogeneity, dissipation,\nanharmonicity) into a single model.",
        "positive": "Three dimensional instability of flexible ferromagnetic filament loop: Dynamics of flexible ferromagnetic filaments in an external magnetic field is\nconsidered. We report the existence of a buckling instability of the\nferromagnetic filament at the magnetic field reversion, which leads to the\nformation of a metastable loop. Its relaxation through three dimensional\ntransformation of the configurations is observed experimentally and confirmed\nby numerical simulations. Bending modulus of the flexible ferromagnetic\nfilaments synthesized by linking micron size core-shell ferromagnetic particles\nwith DNA fragments is estimated by comparison of the parameters of the loops\nobserved in the experiment with theoretical calculations. Formation of the loop\nand its relaxation are characterized by the numerically calculated writhe\nnumber. The relaxation time of the loop allows us to estimate the hydrodynamic\ndrag of the filament."
    },
    {
        "anchor": "Large Slowdown of Water Dynamics at Stacked Phospholipid Membranes for\n  Increasing Hydration Level: All-Atoms Molecular Dynamics: Water hydrating phospholipid membranes determine their stability and\nfunction, as well as their interaction with other molecules. In this article we\nstudy, using all-atom molecular dynamics simulations, the rotational and\ntranslational dynamical properties of water molecules confined in stacked\nphospholipid membranes at different levels of hydration, from poorly hydrated\nto a completely hydrated membrane. We find that both the translational and the\nreorientation dynamics of water are dramatically slowed down as the hydration\nis reduced. Analyzing in details the structure and dynamics of the hydrogen\nbond at the interface, we show that both those among water molecules and those\nbetween water and lipids slow down by decreasing the hydration, however the\nlatter are always slower than the former. By increasing hydration, water\nsaturates all the possible hydrogen bonds with the lipids and, by further\nincrease of hydration, the hydrogen bonds among waters becomes the majority.\nHowever, the dynamics of the water-lipids hydrogen bonds becomes up to one\norder of magnitude slower than that of the water-water hydrogen bonds, inducing\na large slowing down of the dynamics of the entire system even at large\nhydration level.",
        "positive": "Local structure of Liquid-Vapour Interfaces: The structure of a simple liquid may be characterised in terms of ground\nstate clusters of small numbers of atoms of that same liquid. Here we use this\nsensitive structural probe to consider the effect of a liquid-vapour interface\nupon the liquid structure. At higher temperatures (above around half the\ncritical temperature) we find that the predominant effect of the interface is\nto reduce the local density, which significantly suppresses the local cluster\npopulations. At lower temperatures, however, pronounced interfacial layering is\nfound. This appears to be connected with significant orientational ordering of\nclusters based on 3- and 5-membered rings, with the rings aligning\nperpendicular and parallel to the interface respectively. At all temperatures,\nwe find that the population of five-fold symmetric structures is suppressed,\nrather than enhanced, close to the interface."
    },
    {
        "anchor": "Adsorbed and Grafted Polymers at Equilibrium: This chapter deals with various aspects related to the adsorption of long\nchain-like macromolecules (polymers) onto solid surfaces. Physical aspects of\nthe adsorption mechanism are elaborated mainly at thermodynamical equilibrium.\nThe basic features needed in modeling of this adsorption are discussed. We\nfirst discuss the adsorption of a single and long polymer chain to the surface.\nThe surface interaction is modeled by a potential well with a long-ranged\nattractive tail. A simple mean-field theory description is presented and the\nconcept of polymer \"blobs\" is used to describe the conformation of the chain at\nthe surface. The thickness of the adsorbed layer depends on several polymer and\nsurface parameters. Fluctuation corrections to mean-field theory are also\ndiscussed. We then review adsorption as well as depletion processes in the\nmany-chain case. Profiles, changes in the surface tension and polymer surface\nexcess are calculated within mean-field theory. Corrections due to fluctuations\nin good solvent are taken into account using scaling concepts. The proximal\nexponent is introduced in analogy to surface critical phenomena. The\ninteraction between two surfaces with adsorbed polymer layers is discussed, and\nvarious cases leading to attractive and repulsive interactions are mentioned.\nPolyelectrolytes are of practical importance due to their water solubility; we\ngive a short summary of recent progress in this rapidly evolving field. The\nbehavior of grafted polymers, i.e., polymers which are anchored with one end to\na solid substrate is also reviewed.",
        "positive": "Distinct impacts of polar and nematic self-propulsion on active\n  unjamming: Though jamming transitions are long studied in condensed matter physics and\ngranular systems, much less is known about active jamming (or unjamming), which\ncommonly takes place in living materials. In this paper, we explore, by\nmolecular dynamic simulations, the jamming-unjamming transition in a dense\nsystem of active semi-flexible filaments. In particular we characterise the\ndistinct impact of polar versus nematic driving for different filament rigidity\nand at varying density. Our results show that high densities of dynamic active\nfilaments can be achieved by only changing the nature of the active force,\nnematic or polar. Interestingly, while polar driving is more effective at\nunjamming the system at high densities below confluency, we find that at even\nhigher densities nematic driving enhances unjamming compared to its polar\ncounterpart. The effect of varying the rigidity of filaments is also\nsignificantly different in the two cases: while for nematic driving lowering\nbending rigidity unjams the system, we find an intriguing re-entrant\njamming-unjamming-jamming transition for polar driving as the filament rigidity\nis lowered. While the first transition (unjamming) is driven by softening due\nto reduced rigidity, the second transition (jamming) is a cooperative effect of\nordering and coincides with the emergence of nematic order in the system.\nTogether, through a generic model of self-propelled flexible filaments, our\nresults demonstrate how tuning the nature of self-propulsion and flexibility\ncan be employed by active materials to achieve high densities without getting\njammed."
    },
    {
        "anchor": "Enhancing the Refractive Index of Polymers with a Plant-Based Pigment: Polymeric materials are prized for their formability, low density, and\nfunctional versatility. However, the refractive indices of common polymers fall\nin a relatively narrow range between 1.4 and 1.6. Here, we demonstrate that\nloading commercially-available polymers with large concentrations of a\nplant-based pigment can effectively enhance their refractive index.For\npolystyrene loaded with 67w/w\\% $\\beta$-carotene, we achieve a peak value of\n2.2 near the absorption edge at $531~\\mathrm{nm}$, while maintaining values\nabove 1.75 across longer wavelengths of the visible spectrum. Despite high\npigment loadings, this blend maintains the thermoforming ability of\npolystyrene, and $\\beta$-carotene remains molecularly dispersed. Similar\nresults are demonstrated for the plant-derived polymer ethyl cellulose. Since\nthe refractive index enhancement is intimately connected to the introduction of\nstrong absorption, it is best suited to applications where light travels short\ndistances through the material, such as reflectors and nanophotonic systems.We\nexperimentally demonstrate enhanced reflectance from films, as large as\nseven-fold for ethyl cellulose at selected wavelengths. Theoretical\ncalculations that highlight that this simple strategy can significantly\nincrease light scattering by nanoparticles and enhance the performance of Bragg\nreflectors.",
        "positive": "When bigger is faster: a self-van Hove analysis of the enhanced\n  self-diffusion of non-commensurate guest particles in smectics: We investigate the anomalous dynamics in smectic phases of short host rods\nwhere, counter-intuitively, long guest rod-shaped particles diffusive faster\nthan the short host ones, due to their precise size mismatch. In addition to\nthe previously reported mean-square displacement, we analyze the time evolution\nof the Self-van Hove functions G(r,t), as this probability density function\nuncovers intrinsic heterogeneous dynamics. Through this analysis, we show that\nthe dynamics of the host particles parallel to the director becomes\nnon-gaussian and therefore heterogeneous after the nematic-to-smectic-A phase\ntransition, even though it exhibits a nearly diffusive behavior according to\nits mean-square displacement. In contrast, the non-commensurate guest particles\ndisplay Gaussian dynamics of the parallel motion, up to the transition to the\nsmectic-B phase. Thus, we show that the Self-van Hove function is a very\nsensitive probe to account for the instantaneous and heterogeneous dynamics of\nour system, and should be more widely considered as a quantitative and\ncomplementary approach of the classical mean-square displacement\ncharacterization in diffusion processes."
    },
    {
        "anchor": "Magnetic Propulsion of Self-Assembled Colloidal Carpets: Efficient Cargo\n  Transport via a Conveyor-Belt Effect: We demonstrate a general method to assemble and propel highly maneuverable\ncolloidal carpets which can be steered via remote control in any direction of\nthe plane. These colloidal micropropellers are composed by an ensemble of\nspinning rotors and can be readily used to entrap, transport, and release\nbiological cargos on command via a hydrodynamic conveyor-belt effect. An\nefficient control of the cargo transportation combined with remarkable\n\"healing\" ability to surpass obstacles demonstrate a great potential towards\ndevelopment of multifunctional smart devices at the microscale.",
        "positive": "Dense bubble flow in a silo: an unusual flow of a dispersed medium: The dense flow of air bubbles in a two-dimensional silo (through an aperture\nD) filled with a liquid is studied experimentally. A particle tracking\ntechnique has been used to bring out the main properties of the flow:\ndisplacements of the bubbles, transverse and axial velocities. The behavior of\nthe air bubbles is observed to present similarities with non-deformable solid\ngrains in a granular flow. Nevertheless, a correlation between the bubble\nvelocities and their deformations has been evidenced. Moreover, a new discharge\nlaw (Beverloo-like) must be considered for such a system, where the flow rate\nis observed to vary as D^{1/2} and depends on the deformability of the\nparticles."
    },
    {
        "anchor": "Simulations of water nano-confined between corrugated planes: Two-dimensionally nanoconfined water between ideal planar walls has been the\nsubject of ample study, aiming at understanding the intrinsic response of water\nto confinement, avoiding the consideration of the chemistry of actual confining\nmaterials. In this work, we study the response of such nanoconfined water under\na periodic confining potential by means of computer simulations, both using\nempirical potentials and from first-principles. We propose a periodic confining\npotential emulating the atomistic oscillation of the confining walls, which\nallows varying the lattice parameter and amplitude of the oscillation. We do it\nfor a triangular lattice, with several values of the lattice parameter: one\nwhich is ideal for commensuration with layers of Ih ice, and other values that\nwould correspond to more realistic substrates. For the former, an overall rise\nof the melting temperature is observed. The liquid maintains a bi-layer\ntriangular structure, however, despite the fact that it is not favoured by the\nexternal periodicity. The first-principles liquid is significantly affected by\nthe modulation in its layering and stacking even at relatively small amplitudes\nof the confinement modulation. Beyond some critical modulation amplitude the\nhexatic phase present in flat confinement is replaced by a trilayer crystalline\nphase unlike any of the phases encountered for flat confinement. For more\nrealistic lattice parameters, the liquid does not display higher tendency to\nfreeze, but it clearly shows inhomogeneous behaviour as the strength of the\nrugosity increases. In spite of this expected inhomogeneity, the structural and\ndynamical response of the liquid is surprisingly insensitive to the external\nmodulation. Although the first-principles calculations give a more triangular\nliquid than the one observed with empirical potentials, both agree remarkably\nwell for the main conclusions of the study.",
        "positive": "Critical scaling of diffusion coefficients and size of rigid clusters of\n  soft athermal particles under shear: We numerically investigate the self-diffusion coefficient and correlation\nlength of the rigid clusters (i.e., the typical size of the collective motions)\nin sheared soft athermal particles. Here we find that the rheological flow\ncurves on the self-diffusion coefficient are collapsed by the proximity to the\njamming transition density. This feature is in common with the well-established\ncritical scaling of flow curves on shear stress or viscosity. We furthermore\nreveal that the divergence of the correlation length governs the critical\nbehavior of the diffusion coefficient, where the diffusion coefficient is\nproportional to the correlation length and the strain rate for a wide range of\nthe strain rate and packing fraction across the jamming transition density."
    },
    {
        "anchor": "Anomalously fast kinetics of lipid monolayer buckling: We re-examine previous observations of folding kinetics of compressed lipid\nmonolayers in light of the accepted mechanical buckling mechanism recently\nproposed [L. Pocivavsek et al., Soft Matter, 2008, 4, 2019]. Using simple\nmodels, we set conservative limits on a) the energy released in the mechanical\nbuckling process and b) the kinetic energy entailed by the observed folding\nmotion. These limits imply a kinetic energy at least thirty times greater than\nthe energy supplied by the buckling instability. We discuss possible extensions\nof the accepted picture that might resolve this discrepancy.",
        "positive": "Inherent thermal convection in a gas inside a box under a gravity field: We theoretically prove the existence in granular fluids of a thermal\nconvection that is inherent, in the sense that is always present and has no\nthermal gradient threshold (convection occurs for all finite values of the\nRayleigh number). More specifically, we study a gas of inelastic smooth hard\ndisks enclosed in a rectangular region under a constant gravity field. The\nvertical walls act as energy sinks (i.e., inelastic walls that are parallel to\ngravity) whereas the other two walls are perpendicular to gravity and act as\nenergy sources. We show that this convection is due to the combined action of\ndissipative lateral walls and a volume force (in this case, gravitation).\nHence, we call it \\textit{dissipative lateral walls convection}, DLWC. Our\ntheory, that describes also the limit case of elastic collisions, shows that\ninelastic particle collisions enhance the DLWC. We perform our study via\nnumerical solutions (volume element method) of the corresponding hydrodynamic\nequations, in an extended Boussinesq approximation. We show our theory\ndescribes the essentials of the results for similar (but more complex)\nlaboratory experiments."
    },
    {
        "anchor": "Micro- and Macrorheological Properties of Isotropically Cross-linked\n  Actin Networks: Cells make use of semi-flexible biopolymers such as actin or intermediate\nfilaments to control their local viscoelastic response by dynamically adjusting\nthe concentration and type of cross-linker molecules. The microstructure of the\nresulting networks mainly determines their mechanical properties. It remains an\nimportant challenge to relate structural transitions to both the molecular\nproperties of the cross-linking molecules and the mechanical response of the\nnetwork. This can be achieved best by well-defined in vitro model systems in\ncombination with microscopic techniques. Here, we show that with increasing\nconcentrations of the cross-linker HMM (heavy meromyosin) a transition in the\nmechanical network response occurs. At low cross-linker densities the network\nelasticity is dominated by the entanglement length of the polymer, while at\nhigh HMM densities the cross-linker distance determines the elastic behavior.\nUsing microrheology the formation of heterogeneous networks is observed at low\ncross-linker concentrations. Micro- and macrorheology both report the same\ntransition to a homogeneous cross-linked phase. This transition is set by a\nconstant average cross-linker distance. Thus, the micro- and macromechanical\nproperties of isotropically cross-linked in vitro actin networks are determined\nby only one intrinsic network parameter.",
        "positive": "Nematic droplets at fibres: The emergence of new techniques for the fabrication of nematic droplets with\nnontrivial topology provides new routes for the assembly of responsive devices.\nHere we perform a numerical study of spherical nematic droplets on fibres. We\nanalyse the equilibrium textures and find that, under certain conditions,the\nnematic can avoid the nucleation of topological defects. We consider in detail\na homeotropic nematic droplet wrapped around a fibre with planar anchoring. We\ninvestigate the effect of an electric field on the texture of this droplet such\ntype of system. In the presence of a DC field, the system undergoes a\nFreederickzs-like transition above a given threshold $E_c$. We also consider AC\nfields, at high and low frequencies, and find that the textures are similar to\nthose observed for static fields, in contrast with recently reported\nexperiments."
    },
    {
        "anchor": "The influence of metallic particle size on the mechanical properties of\n  PTFE-Al-W powder composites: The dynamic mechanical properties of reactive materials (e.g., high density\nmixtures of polytetraflouroethylene (PTFE), aluminum (Al) and tungsten (W)\npowders) can be tailored by changing the morphology of the particles and\nporosity. Cold isostatically pressed PTFE-Al-W powder composites with fine\nmetallic particles and a higher porosity exhibited higher ultimate compressive\nstrength than less porous composites having equivalent mass ratios with coarse\nW particles. The mesoscale force chains between the fine metallic particles are\nresponsible for this unusual phenomenon. We observed macrocracks below the\ncritical failure strain for the matrix and a competition between densification\nand fracture in some porous samples in dynamic tests.",
        "positive": "Internal magnetic field distribution in plasmas: We calculate stationary probability distribution of magnetic field, generated\nby moving charges of plasma environment, and stationary probability\ndistribution of force, acting on charged particle in this environment, with\nmagnetic interaction taken into account. While the former happens to be the\nHoltsmark distribution, the latter is a modified Holtsmark distribution. In\ncontrast to prior works, we did no assumptions on the velocity distribution\nfunction and thus obtained results should be applicable to wider spectrum of\nmodels. Presented results can be experimentally verified through studies of\nZeeman effect or movement of small charged Brownian particles in plasma."
    },
    {
        "anchor": "Influence of magnetic field on evaporation of a ferrofluid droplet: Influence of magnitude and direction of static magnetic field applied on a\ndrying drop of a laboratory synthesized water base ferrofluid placed on a plane\nglass plate is investigated. Like all other multi-component fluid this drop\nalso exhibited familiar coffee ring pattern in absence of field while, this\npattern is modulated by applying magnetic field and thickness of the ring\nmodulated by the applied field and thickness of the ring decreases\nexponentially with increase in field when direction of field is normal to the\nplane of the substrate. Effect of the field on the evaporation rate and\ntemporal variation of contact angle is also studied. Results are analysed in\nlight of available models. The findings may be useful in applications like\nink-jet printing, painting and display devices involving ferrofluids.",
        "positive": "Geometrically programmed self-limited assembly of tubules using DNA\n  origami colloids: Self-assembly is one of the most promising strategies for making functional\nmaterials at the nanoscale, yet new design principles for making self-limiting\narchitectures, rather than spatially unlimited periodic lattice structures, are\nneeded. To address this challenge, we explore the trade-offs between\naddressable assembly and self-closing assembly of a specific class of\nself-limiting structures: cylindrical tubules. We make triangular subunits\nusing DNA origami that have specific, valence-limited interactions and designed\nbinding angles, and study their assembly into tubules that have a self-limited\nwidth that is much larger than the size of an individual subunit. In the\nsimplest case, the tubules are assembled from a single component by\ngeometrically programming the dihedral angles between neighboring subunits. We\nshow that the tubules can reach many micrometers in length and that their\naverage width can be prescribed through the dihedral angles. We find that there\nis a distribution in the width and the chirality of the tubules, which we\nrationalize by developing a model that considers the finite bending rigidity of\nthe assembled structure as well as the mechanism of self-closure. Finally, we\ndemonstrate that the distributions of tubules can be further sculpted by\nincreasing the number of subunit species, thereby increasing the assembly\ncomplexity, and demonstrate that using two subunit species successfully reduces\nthe number of available end states by half. These results help to shed light on\nthe roles of assembly complexity and geometry in self-limited assembly and\ncould be extended to other self-limiting architectures, such as shells,\ntoroids, or triply-periodic frameworks."
    },
    {
        "anchor": "A heuristic approach for the densest packing fraction of hard-sphere\n  mixtures: In a previous work, a simple approach to derive the jamming packing fraction\nof a hard-sphere mixture from the knowledge of the random close-packing\nfraction of the monocomponent system was proposed. Now, an extension of that\napproach is applied to provide an approximate formula for the densest packing\nfraction of a given hard-sphere mixture in terms of the fcc close-packing\nfraction of a monocomponent hard-sphere system and of a single parameter\nencapsulating the dependence on the size ratios and the number of spheres in\nthe unit cell. Comparison with recent results for such densest packing fraction\nof binary and ternary systems is performed and reasonable agreement is\nobtained.",
        "positive": "Role of Metastable States in Phase Ordering Dynamics: We show that the rate of separation of two phases of different densities\n(e.g. gas and solid) can be radically altered by the presence of a metastable\nintermediate phase (e.g. liquid). Within a Cahn-Hilliard theory we study the\ngrowth in one dimension of a solid droplet from a supersaturated gas. A moving\ninterface between solid and gas phases (say) can, for sufficient (transient)\nsupersaturation, unbind into two interfaces separated by a slab of metastable\nliquid phase. We investigate the criteria for unbinding, and show that it may\nstrongly impede the growth of the solid phase."
    },
    {
        "anchor": "Like-Charge Attraction between Metal Nanoparticles in a 1:1 Electrolyte\n  Solution: We calculate the force between two spherical metal nanoparticles of charge Q\n1 and Q 2 in a dilute 1:1 electrolyte solution. Numerically solving the\nnon-linear Poisson-Boltzmann equation, we find that metal nanoparticles with\nthe same sign of charge can attract one another. This is fundamentally\ndifferent from what is found for like-charged, non-polarizable, colloidal\nparticles, the two body interaction potential for which is always repulsive\ninside a dilute 1:1 electrolyte. Furthermore, existence of like-charge\nattraction between spherical metal nanoparticles is even more surprising in\nview of the result that such attraction is impossible between parallel metal\nslabs, showing the fundamental importance of curvature. To overcome a slow\nconvergence of the numerical solution of the full non-linear Poisson-Boltzmann\nequation, we developed a modified Derjaguin approximation which allows us to\naccurate and rapidly calculate the interaction potential between two metal\nnanoparticles, or between a metal nanoparticle and a phospholipid membrane.",
        "positive": "Active emulsions in living cell membranes driven by contractile stresses\n  and transbilayer coupling: The spatiotemporal organisation of proteins and lipids on the cell surface\nhas direct functional consequences for signaling, sorting and endocytosis.\nEarlier studies have shown that multiple types of membrane proteins including\ntransmembrane proteins that have cytoplasmic actin binding capacity and\nlipid-tethered GPI-anchored proteins (GPI-APs) form nanoscale clusters driven\nby active contractile flows generated by the actin cortex. To gain insight into\nthe role of lipids in organizing membrane domains in living cells, we study the\nmolecular interactions that promote the actively generated nanoclusters of\nGPI-APs and transmembrane proteins. This motivates a theoretical description,\nwherein a combination of active contractile stresses and transbilayer coupling\ndrive the creation of active emulsions, mesoscale liquid ordered (lo) domains\nof the GPI-APs and lipids, at temperatures greater than equilibrium lipid-phase\nsegregation. To test these ideas we use spatial imaging of homo-FRET combined\nwith local membrane order and demonstrate that mesoscopic domains enriched in\nnanoclusters of GPI-APs are maintained by cortical actin activity and\ntransbilayer interactions, and exhibit significant lipid order, consistent with\npredictions of the active composite model."
    },
    {
        "anchor": "Ab-initio study of model guanine assemblies: The role of pi-pi coupling\n  and band transport: Several assemblies of guanine molecules are investigated by means of\nfirst-principle calculations. Such structures include stacked and\nhydrogen-bonded dimers, as well as vertical columns and planar ribbons,\nrespectively, obtained by periodically replicating the dimers. Our results are\nin good agreement with experimental data for isolated molecules, isolated\ndimers, and periodic ribbons. For stacked dimers and columns, the stability is\naffected by the relative charge distribution of the pi orbitals in adjacent\nguanine molecules. pi-pi coupling in some stacked columns induces dispersive\nenergy bands, while no dispersion is identified in the planar ribbons along the\nconnections of hydrogen bonds. The implications for different materials\ncomprised of guanine aggregates are discussed. The bandstructure of dispersive\nconfigurations may justify a contribution of band transport (Bloch type) in the\nconduction mechanism of deoxyguanosine fibres, while in DNA-like configurations\nband transport should be negligible.",
        "positive": "Specific Ion Effects of Trivalent Cations on the Structure and Charging\n  State of $\u03b2$-Lactoglobulin Adsorption Layers: In this work, we addressed the effects of Y$^{3+}$ and Nd$^{3+}$ cations on\nthe adsorption of the whey protein $\\beta$-lactoglobulin (BLG) at air-water\ninterfaces as a function of electrolyte concentration. Both cations caused very\nsimilar but dramatic changes at the interface and in the bulk solution. Here,\nmeasurements of the electropho-retic mobility and vibrational sum-frequency\ngeneration spectroscopy (SFG) were applied and consistently showed a reversal\nof the BLG net charge at remarkably low ion concentrations of 30 (bulk) and 40\n(interface) $\\mu$M of Y$^{3+}$ or Nd$^{3+}$ for a BLG concentration of 15\n$\\mu$M. SFG spectra of carboxylate stretching vibrations from Asp or Glu\nresidues of interfacial BLG showed significant changes in the carboxylate\nstretching frequency, which we associate to specific and efficient bind-ing of\nY$^{3+}$ or Nd$^{3+}$ ions to the proteins carboxylate groups. Characteristic\nreentrant condensation for BLG moieties with bound trivalent ions was found in\na broad concentration range around the point of zero net charge. The highest\ncolloidal stability of BLG was found for ion concentrations <20$\\mu$M and\n>50$\\mu$M. Investigations on macroscopic foams from BLG solutions, revealed the\nexistence of structure-property relations between the interfacial charging\nstate and the foam stability. In fact, a minimum in foam stability at 20$\\mu$M\nion concentration was found when the interfacial net charge was negligible. Our\nresults provide new information on the charge reversal at the liquid-gas\ninterface of protein/ion dispersions. Therefore, we see our findings as an\nimportant step in the clarification of reentrant con-densation effects at\ninterfaces and their relevance to foam stability."
    },
    {
        "anchor": "Capturing the dynamics of a two orifice silo with the \u03bc(I) model and\n  extensions: Granular material in a silo with two openings can display a `flow rate dip',\nwhere a non-monotonic relationship between flow rate and orifice separation\noccurs. In this paper we study continuum modelling of the silo with two\nopenings. We find that the $\\mu(I)$ rheology can capture the flow rate dip if\nphysically relevant friction parameters are used. We also extend the model by\naccounting for wall friction, dilatancy, and non-local effects. We find that\naccounting for the wall friction using a Hele-Shaw model better replicates the\nqualitative characteristics of the flow rate dip seen in experimental data,\nwhile dilatancy and non-local effects have very little effect on the\nqualitative characteristics of the mass flow rate dip. However, we find that\nall three of these factors have a significant impact on the mass flow rate,\nindicating that a continuum model which accurately predicts flow rate will need\nto account for these effects.",
        "positive": "Three length scales colloidal gels: the clusters of clusters versus the\n  interpenetrating clusters approach: Typically, in quiescent conditions, attractive colloids at low volume\nfractions form fractal gels structured into two length scales: the colloidal\nand the fractal cluster scales. However when flow interfere with gelation\ncolloidal fractal gels may display three distinct length scales [Dag\\`es, et\nal., Soft Matter 18, 6645 (2022)]. Following those recent experimental\ninvestigations, we derive two models that account for the structure and the\nrheological properties of such atypical colloidal gels. The gel elasticity is\ninferred from scaling arguments and the structure is translated into scattering\nintensities following the global scattering functions approach proposed by\nBeaucage and typically measured in small angle X-ray scattering (SAXS). In both\nmodels, we consider that the colloids condensate into fractal clusters. In the\nclusters of clusters model, the clusters form superagregates which then build\nthe gel network. In the interpenetrating clusters model, the clusters\ninterpenetrate one-another to form the gel network. Those two models are then\nutilised to analyse rheo-SAXS experiments carried out on carbon black gels\nformed through flow cessation. The results of the analysis vouch for the\nclusters of clusters model with a densification of the structures as the gel\ncharacteristic length scales increase."
    },
    {
        "anchor": "Elasticidad de las membranas biol\u00f3gicas: In this article we review the present knowledge on the elastic properties of\nmembranes of biological origin. Assuming the fluid mosaic hypothesis, we\nconsider the phospholipid bilayer as the structural base of a biological\nmembrane. We expose a model due to Helfrich which can be used to obtain an\nexpression for the membrane elastic energy. The free energy is completely\ncharacterized by two local principal curvatures and four parameters that depend\non the chemical composition of the membrane and its local environment. In\naddition we present the theoretical justification of an experimental method\n(the Micropipette Manipulation technique) that may be used to measure the\nmembrane rigidity. Finally, we describe some physical consequences of these\nconcepts, such as the explanation of the lamellar-sponge phase transition and\nthe emergence of the steric interaction between membranes.\n  ------\n  Se presenta una revisi\\'on del conocimiento actual sobre las propiedades\nel\\'asticas de las membranas. Bajo la hip\\'otesis del mosaico fluido se\nconsidera a una bicapa de fosfol\\'ipido como la base estructural de una\nmembrana biol\\'ogica y se expone un modelo debido a Helfrich a partir del\ncu\\'al se obtiene una expresi\\'on para la energ\\'ia el\\'astica de una membrana.\nLa energ\\'ia libre queda completamente caracterizada por sus curvaturas locales\nprincipales y cuatro par\\'ametros dependientes de la composici\\'on qu\\'imica de\nla membrana y de su entorno local. Se expone la justificaci\\'on te\\'orica de un\nm\\'etodo experimental que permite medir la constante el\\'astica de curvatura\nmedia de una membrana. Finalmente se describen algunas consecuencias f\\'isicas\nde estos conceptos, como la explicaci\\'on de la transici\\'on de una fase\nlamelar a una esponja, o la aparici\\'on de la interacci\\'on est\\'erica entre\nmembranas.",
        "positive": "Molecular field theory for biaxial smectic A liquid crystals: Thermotropic biaxial nematic phases seem to be rare, but biaxial smectic A\nphases less so. Here we use molecular field theory to study a simple\ntwo-parameter model, with one parameter promoting a biaxial phase and the\nsecond promoting smecticity. The theory combines the biaxial Maier-Saupe and\nMcMillan models. We use alternatively the Sonnet-Virga-Durand (SVD) and\ngeometric mean approximations (GMA) to characterize molecular biaxiality by a\nsingle parameter. For non-zero smecticity and biaxiality, the model always\npredicts a ground state biaxial smectic A phase. For a low degree of smectic\norder, the phase diagram is very rich, predicting uniaxial and biaxial nematic\nand smectic phases, with in addition a variety of tricritical and tetracritical\npoints. For higher degrees of smecticity, the region of stability of the\nbiaxial nematic phase is restricted and eventually disappears, yielding to the\nbiaxial smectic phase. Phase diagrams from the two alternative approximations\nfor molecular biaxiality are similar, except inasmuch that SVD allows for a\nfirst order isotropic-nematic biaxial transition, whereas GMA predicts a Landau\npoint separating isotropic and biaxial nematic phases. We speculate that the\nrarity of thermotropic biaxial nematic phases is partly a consequence of the\npresence of stabler analogous smectic phases."
    },
    {
        "anchor": "Dynamical density functional theory for dense atomic liquids: Starting from Newton's equations of motion, we derive a dynamical density\nfunctional theory (DDFT) applicable to atomic liquids. The theory has the\nfeature that it requires as input the Helmholtz free energy functional from\nequilibrium density functional theory. This means that, given a reliable\nequilibrium free energy functional, the correct equilibrium fluid density\nprofile is guaranteed. We show that when the isothermal compressibility is\nsmall, the DDFT generates the correct value for the speed of sound in a dense\nliquid. We also interpret the theory as a dynamical equation for a coarse\ngrained fluid density and show that the theory can be used (making further\napproximations) to derive the standard mode coupling theory that is used to\ndescribe the glass transition. The present theory should provide a useful\nstarting point for describing the dynamics of inhomogeneous atomic fluids.",
        "positive": "Shear thickening of cornstarch suspensions: We study the rheology of cornstarch suspensions, a non-Brownian particle\nsystem that exhibits discontinuous shear thickening. Using magnetic resonance\nimaging (MRI), the local properties of the flow are obtained by the\ndetermination of local velocity profiles and concentrations in a Couette cell.\nFor low rotational rates, we observe shear localization characteristic of yield\nstress fluids. When the overall shear rate is increased, the width of the\nsheared region increases. The discontinuous shear thickening is found to set in\nat the end of this shear localization regime when all of the fluid is sheared:\nthe existence of a nonflowing region, thus, seems to prevent or delay shear\nthickening. Macroscopic observations using different measurement geometries\nshow that the smaller the gap of the shear cell, the lower the shear rate at\nwhich shear thickening sets in. We, thus, propose that the discontinuous shear\nthickening of cornstarch suspensions is a consequence of dilatancy: the system\nunder flow attempts to dilate but instead undergoes a jamming transition,\nbecause it is confined. This proposition is confirmed by an independent\nmeasurement of the dilation of the suspension as a function of the shear rate.\nIt is also explains the MRI observations: when flow is localized, the\nnonflowing region plays the role of a \"dilatancy reservoir\" which allows the\nmaterial to be sheared without jamming."
    },
    {
        "anchor": "Propagation of Tension along a Polymer Chain: We study the propagation of tension caused by an external force along a long\npolymeric molecule in two different settings, namely along a free polymer in 3d\nspace being pulled from one end, and along a pre-stretched circular polymer,\nconfined in a narrow circular tube. We show that in both cases, the tension\npropagation is governed by a diffusion equation, and in particular, the tension\nfront propagates as $t^{1/2}$ along the contour of the chain. The results are\nconfirmed numerically, and by molecular dynamics simulations in the case of the\n3d polymer. We also compare our results with the previously suggested ones for\nthe translocation setting, and discuss why tension propagation is slower in\nthat case.",
        "positive": "Shear-driven solidification and nonlinear elasticity in epithelial\n  tissues: Biological processes, from morphogenesis to tumor invasion, spontaneously\ngenerate shear stresses inside living tissue. The mechanisms that govern the\ntransmission of mechanical forces in epithelia and the collective response of\nthe tissue to bulk shear deformations remain, however, poorly understood. Using\na minimal cell-based computational model, we investigate the constitutive\nrelation of confluent tissues under simple shear deformation. We show that an\ninitially undeformed fluidlike tissue acquires finite rigidity above a critical\napplied strain. This is akin to the shear-driven rigidity observed in other\nsoft matter systems. Interestingly, shear-driven rigidity can be understood by\na critical scaling analysis in the vicinity of the second order critical point\nthat governs the liquid-solid transition of the undeformed system. We further\nshow that a solidlike tissue responds linearly only to small strains and but\nthen switches to a nonlinear response at larger stains, with substantial\nstiffening. Finally, we propose a mean-field formulation for cells under shear\nthat offers a simple physical explanation of shear-driven rigidity and\nnonlinear response in a tissue."
    },
    {
        "anchor": "Density functional methods for polymers: a coil-globule transition case\n  study: We consider a free energy functional on the monomer density function that is\nsuitable for the study of coil-globule transition. We demonstrate, with\nexplicitly stated assumptions, why the entropic contribution is in the form of\nthe Kullback-Leibler distance, and that the energy contribution is given by\ntwo-body and three-body terms. We then solve for the free energy analytically\non a set of trial density functions, and reproduce de Gennes' classical theory\non polymer coil-globule transition. We then discuss how our formalism can be\napplied to study polymer dynamics from the perspective of dynamical density\nfunction theory.",
        "positive": "Critical Casimir torques and forces acting on needles in two spatial\n  dimensions: We investigate the universal orientation-dependent interactions between\nnon-spherical colloidal particles immersed in a critical solvent by studying\nthe instructive paradigm of a needle embedded in bounded two-dimensional Ising\nmodels at bulk criticality. For a needle in an Ising strip the interaction on\nmesoscopic scales depends on the width of the strip and the length, position,\nand orientation of the needle. By lattice Monte Carlo simulations we evaluate\nthe free energy difference between needle configurations being parallel and\nperpendicular to the strip. We concentrate on small but nonetheless mesoscopic\nneedle lengths for which analytic predictions are available for comparison. All\ncombinations of boundary conditions for the needles and boundaries are\nconsidered which belong to either the \"normal\" or the \"ordinary\" surface\nuniversality class, i.e., which induce local order or disorder, respectively.\nWe also derive exact results for needles of arbitrary mesoscopic length, in\nparticular for needles embedded in a half plane and oriented perpendicular to\nthe corresponding boundary as well as for needles embedded at the center line\nof a symmetric strip with parallel orientation."
    },
    {
        "anchor": "Capillary force on a tilted cylinder: AFM measurements: We investigate the capillary force that applies on a tilted cylinder as a\nfunction of its dipping angle i, using a home-built tilting Atomic Force\nMicroscope (AFM) with custom made probes. A micrometric-size rod is glued at\nthe end of an AFM cantilever of known stiffness, whose deflection is measured\nwhen the cylindrical probe is dipped in and retracted from reference liquids.\nWe show that a torque correction is necessary to understand the measured\ndeflection. The results are compatible with a vertical capillary force varying\nas 1/ cos i, in agreement with a recent theoretical prediction. We also discuss\nthe accuracy of the method for measuring the surface tension times the cosine\nof the contact angle of the liquid on the hanging fiber.",
        "positive": "Dynamics of the superfluid to Mott insulator transition in one dimension: We numerically study the superfluid to Mott insulator transition for bosonic\natoms in a one dimensional lattice by exploiting a recently developed\nsimulation method for strongly correlated systems. We demonstrate this methods\naccuracy and applicability to Bose-Hubbard model calculations by comparison\nwith exact results for small systems. By utilizing the efficient scaling of\nthis algorithm we then concentrate on systems of comparable size to those\nstudied in experiments and in the presence of a magnetic trap. We investigate\nspatial correlations and fluctuations of the ground state as well as the nature\nand speed at which the superfluid component is built up when dynamically\nmelting a Mott insulating state by ramping down the lattice potential. This is\nperformed for slow ramping, where we find that the superfluid builds up on a\ntime scale consistent with single-atom hopping and for rapid ramping where the\nbuildup is much faster than can be explained by this simple mechanism. Our\ncalculations are in remarkable agreement with the experimental results obtained\nby Greiner et al. [Nature (London) 415, 39 (2002)]."
    },
    {
        "anchor": "Phase separation in star polymer-colloid mixtures: We examine the demixing transition in star polymer-colloid mixtures for star\narm numbers f=2,6,16,32 and different star-colloid size ratios. Theoretically,\nwe solve the thermodynamically self-consistent Rogers-Young integral equations\nfor binary mixtures using three effective pair potentials obtained from direct\nmolecular computer simulations. The numerical results show a spinodal\ninstability. The demixing binodals are approximately calculated, and found to\nbe consistent with experimental observations.",
        "positive": "Comment on Justin E. Pye and Connie B. Roth, J. Polym. Sci., Part B\n  Polym.Phys. 2015, 53, 64-75: Two transitions were found by ellipsometry in freestanding high molecular\nweight PS films by Pye and Roth (PR). PR suggested that the upper and the lower\ntransitions both came from the segmental a-relaxation, and the upper transition\noccurs in 90% of the material. In this paper we use dielectric relaxation data\nof freestanding films to rule out their suggestion. Furthermore, we demonstrate\nby experimental evidences that the sub-Rouse modes are coupled to density, and\nrespond to physical aging to validate our interpretation and can explain the\nupper transition."
    },
    {
        "anchor": "Anomalous diffusion and L\u00e9vy walks distinguish active from inertial\n  turbulence: Bacterial swarms display intriguing dynamical states like active turbulence.\nUsing a hydrodynamic model we now show that such dense active suspensions\nmanifest super-diffusion, via L\\'evy walks, which masquerades as a crossover\nfrom ballistic to diffusive scaling in measurements of\nmean-squared-displacements, and is tied to the emergence of hitherto undetected\noscillatory streaks in the flow. Thus, while laying the theoretical framework\nof an emergent advantageous strategy in the collective behaviour of\nmicroorganisms, our study underlines the essential differences between active\nand inertial turbulence.",
        "positive": "Universal low-frequency vibrational modes in silica glasses: It was recently shown that different simple models of glass formers with\nbinary interactions define a universality class in terms of the density of\nstates of their quasi-localized low-frequency modes. Explicitly, once the\nhybridization with standard Debye (extended) modes is avoided, a number of such\nmodels exhibit a universal density of state, depending on the mode frequencies\nas $D(\\omega) \\sim \\omega^4$. It is unknown however how wide is this\nuniversality class, and whether it also pertains to more realistic models of\nglass formers. To address this issue we present analysis of the quasi-localized\nmodes in silica, a network glass which has both binary and ternary\ninteractions. We conclude that in 3-dimensions silica exhibits the very same\nfrequency dependence at low frequencies, suggesting that this universal form is\na generic consequence of amorphous glassiness."
    },
    {
        "anchor": "Nonlinear Effects in the TGB_A Phase: We study the nonlinear interactions in the TGB_A phase by using a\nrotationally invariant elastic free energy. By deforming a single grain\nboundary so that the smectic layers undergo their rotation within a finite\ninterval, we construct a consistent three-dimensional structure. With this\nstructure we study the energetics and predict the ratio between the intragrain\nand intergrain defect spacing, and compare our results with those from linear\nelasticity and experiment.",
        "positive": "Multiscale modelling and homogensation of fibre-reinforced hydrogels for\n  tissue engineering: Tissue engineering aims to grow artificial tissues \\emph{in vitro} to replace\nthose in the body that have been damaged through age, trauma or disease. A\nrecent approach to engineer artificial cartilage involves seeding cells within\na scaffold consisting of an interconnected 3D-printed lattice of polymer fibres\ncombined with a cast or printed hydrogel, and subjecting the construct\n(cell-seeded scaffold) to an applied load in a bioreactor. A key question is to\nunderstand how the applied load is distributed throughout the construct. To\naddress this, we employ homogenisation theory to derive equations governing the\neffective macroscale material properties of a periodic, elastic-poroelastic\ncomposite. We treat the fibres as a linear elastic material and the hydrogel as\na poroelastic material, and exploit the disparate length scales (small\ninter-fibre spacing compared with construct dimensions) to derive macroscale\nequations governing the response of the composite to an applied load. This\nhomogenised description reflects the orthotropic nature of the composite. To\nvalidate the model, solutions from finite element simulations of the\nmacroscale, homogenised equations are compared to experimental data describing\nthe unconfined compression of the fibre-reinforced hydrogels. The model is used\nto derive the bulk mechanical properties of a cylindrical construct of the\ncomposite material for a range of fibre spacings, and to determine the local\nmechanical environment experienced by cells embedded within the construct."
    },
    {
        "anchor": "An introduction to the hydrodynamics of locomotion on small scales: In these lecture notes, I will briefly review the fundamental physical\nprinciples of locomotion in fluids, with a particular emphasis on the\nlow-Reynolds number world.",
        "positive": "Collapse and expansion kinetics of a single polyelectrolyte chain with\n  hydrodynamic interactions: We investigate the collapse and expansion dynamics of a linear\npolyelectrolyte (PE) with hydrodynamic interactions. Using dissipative particle\ndynamics with a bead-spring PE model, long-range electrostatics and explicit\nions we examine how the timescales of collapse $t_\\text{col}$ and expansion\n$t_\\text{exp}$ depend on the chain length $N$, and obtain scaling relationships\n$t_\\text{col}\\sim N^\\alpha$ and $t_\\text{exp}\\sim N^\\beta$. For neutral\npolymers, we derive values of $\\alpha=0.94\\pm0.01$ and $\\beta=1.97\\pm0.10$.\nInterestingly, the introduction of electrostatic interaction markedly shifts\n$\\alpha$ to $\\alpha\\approx1.4\\pm0.1$ for salt concentrations within $c=10^{-4}$\nM to $10^{-2}$ M. A reduction in ion-to-monomer size ratio noticeably reduces\n$\\alpha$. On the other hand, the expansion scaling remains approximately\nconstant, $\\beta \\approx 2$, regardless of salt concentration or ion size\nconsidered. We find $\\beta > \\alpha$ for all conditions considered, implying\nthat expansion is always slower than collapse in the limit of long polymers."
    },
    {
        "anchor": "Elastic behavior of a semiflexible polymer in 3D subject to compression\n  and stretching forces: We elucidate the elastic behavior of a wormlike chain in 3D under compression\nand provide exact solutions for the experimentally accessible force-extension\nrelation in terms of generalized spheroidal wave functions. In striking\ncontrast to the classical Euler buckling instability, the force-extension\nrelation of a clamped semiflexible polymer exhibits a smooth crossover from an\nalmost stretched to a buckled configuration. In particular, the associated\nsusceptibility, which measures the strength of the response of the polymer to\nthe applied force, displays a prominent peak in the vicinity of the critical\nEuler buckling force. For increasing persistence length, the force-extension\nrelation and the susceptibility of semiflexible polymers approach the behavior\nof a classical rod, whereas thermal fluctuations permit more flexible polymers\nto resist the applied force. Furthermore, we find that semiflexible polymers\nconfined to 2D can oppose the applied force more strongly than in 3D.",
        "positive": "Free Energy Landscape of Colloidal Clusters in Spherical Confinement: The structure of finite self-assembling systems depends sensitively on the\nnumber of constituent building blocks. Recently, it was demonstrated that hard\nsphere-like colloidal particles show a magic number effect when confined in\nspherical emulsion droplets. Geometric construction rules permit a few dozen\nmagic numbers that correspond to a discrete series of completely filled\nconcentric icosahedral shells. Here, we investigate the free energy landscape\nof these colloidal clusters as a function of the number of their constituent\nbuilding blocks for system sizes up to several thousand particles. We find that\nminima in the free energy landscape, arising from the presence of filled,\nconcentric shells, are significantly broadened. In contrast to their atomic\nanalogues, colloidal clusters in spherical confinement can flexibly accommodate\nexcess colloids by ordering icosahedrally in the cluster center while changing\nthe structure near the cluster surface. In-between these magic number regions,\nthe building blocks cannot arrange into filled shells. Instead, we observe that\ndefects accumulate in a single wedge and therefore only affect a few\ntetrahedral grains of the cluster. We predict the existence of this wedge by\nsimulation and confirm its presence in experiment using electron tomography.\nThe introduction of the wedge minimizes the free energy penalty by confining\ndefects to small regions within the cluster. In addition, the remaining ordered\ntetrahedral grains can relax internal strain by breaking icosahedral symmetry.\nOur findings demonstrate how multiple defect mechanisms collude to form the\ncomplex free energy landscape of hard sphere-like colloidal clusters."
    },
    {
        "anchor": "Crystals of Na+ ions at the surface of a silica hydrosol: I used x-ray grazing incidence diffraction to measure the spatial\ncorrelations between sodium ions adsorbed with Bjerrum's density at the surface\nof a monodispersed 22-nm-particle colloidal silica solution stabilized by NaOH\nwith a total bulk concentration mol/L. My findings show that the surface\ncompact layer is in a two-dimensional crystalline state (symmetry p2), with\nfour ions forming the unit cell and a ~30 Angstrom translational correlation\nlength between sodium ions.",
        "positive": "Hydrodynamic theory of $p-$atic liquid crystals: We formulate a comprehensive hydrodynamic theory of two-dimensional liquid\ncrystals with generic $p-$fold rotational symmetry, also known as $p-$atics, of\nwhich mematics $(p=2)$ and hexatics $(p=6)$ are the two best known examples.\nPrevious hydrodynamic theories of $p-$atics are characrerized by continuous\n${\\rm O}(2)$ rotational symmetry, which is higher than the discrete rotational\nsymmetry of $p-$atic phases. By contrast, here we demonstrate that the discrete\nrotational symmetry allows the inclusion of additional terms in the\nhydrodynamic equations, which, in turn, lead to novel phenomena, such as the\npossibility of flow alignment at high shear rates, even for $p>2$. Furthermore,\nwe show that any finite imposed shear will induce long-ranged orientational\norder in any $p-$atic liquid crystal, in contrast to the quasi-long-ranged\norder that occurs in the absence of shear. The induced order parameter scales\nlike a non-universal power of the applied shear rate at small shear rates."
    },
    {
        "anchor": "Salt-dependent rheology and surface tension of protein condensates using\n  optical traps: An increasing number of proteins with intrinsically disordered domains have\nbeen shown to phase separate in buffer to form liquid-like phases. These\nprotein condensates serve as simple models for the investigation of the more\ncomplex membrane-less organelles in cells. To understand the function of such\nproteins in cells, the material properties of the condensates they form are\nimportant. However, these material properties are not well understood. Here, we\ndevelop a novel method based on optical traps to study the frequency-dependent\nrheology and the surface tension of PGL-3 condensates as a function of salt\nconcentration. We find that PGL-3 droplets are predominantly viscous but also\nexhibit elastic properties. As the salt concentration is reduced, their elastic\nmodulus, viscosity and surface tension increase. Our findings show that salt\nconcentration has a strong influence on the rheology and dynamics of protein\ncondensates suggesting an important role of electrostatic interactions for\ntheir material properties.",
        "positive": "Capillary interfacial tension in active phase separation: In passive fluid-fluid phase separation, a single interfacial tension sets\nboth the capillary fluctuations of the interface and the rate of Ostwald\nripening. We show that these phenomena are governed by two different tensions\nin active systems, and compute the capillary tension $\\sigma_{cw}$ which sets\nthe relaxation rate of interfacial fluctuations in accordance with capillary\nwave theory. We discover that strong enough activity can cause negative\n$\\sigma_{cw}$. In this regime, depending on the global composition, the system\nself-organizes, either into a microphase-separated state in which coalescence\nis highly inhibited, or into an `active foam' state. Our results are obtained\nfor Active Model B+, a minimal continuum model which, although generic, admits\nsignificant analytical progress."
    },
    {
        "anchor": "Universal size ratios of Gaussian polymers with complex architecture:\n  Radius of gyration vs hydrodynamic radius: The present research is dedicated to provide deeper understanding of the\nimpact of complex architecture of branched polymers on their behaviour in\nsolvents. The folding dynamics of macromolecules and hydrodynamics of polymer\nfluids are strongly dependent on size and shape measures of single\nmacromolecules, which in turn are determined by their topology. For this aim,\nwe use combination of analytical theory, based on path integration method, and\nmolecular dynamics simulations to study structural properties of complex\nGaussian polymers containing $f^c$ linear branches and $f^r$ closed loops\ngrafted to the central core. Using theory we determine the size measures such\nas gyration radius $R_g$ and the hydrodynamic radii $R_H$, and obtain the\nestimates for the size ratio $R_g /R_H$ with its dependence on the\nfunctionality $f=f^c+f^r$ of grafted polymers. In particular, we obtain the\nquantitative estimate of compactification (decrease of size measure) of such\ncomplex polymer architectures with increasing number of closed loops $f^r$ as\ncompared with linear or star-shape molecules of the same total molecular\nweight. Numerical simulations corroborate theoretical prediction that $R_g\n/R_H$ decreases towards unity with increasing $f$. These findings provide\nqualitative description of complex polymers with different arm architecture in\n$\\theta$ solutions.",
        "positive": "The Collective Burst Mechanism of Angular Jumps in Liquid Water: Understanding the microscopic origins of collective reorientational motions\nin aqueous systems requires techniques that allow us to reach beyond our\nchemical imagination. Herein, we elucidate a mechanism using unsupervised\nlearning, showing that large angular jumps in liquid water involve highly\ncooperative orchestrated motions. Our automatized detection of angular\nfluctuations, unravels a heterogeneity in the type of angular jumps occurring\nconcertedly in the system. We show that large orientational motions require a\nhighly collective dynamic process involving correlated motion of up to 10% of\nwater molecules in the hydrogen-bond network that form spatially connected\nclusters. This phenomenon is rooted in the collective fluctuations of the\nnetwork topology which results in the creation of defects in waves on the ThZ\ntimescale. The mechanism we propose involves a cascade of hydrogen-bond\nfluctuations underlying angular jumps and provides new insights into the\ncurrent localized picture of angular jumps, and in its wide use in the\ninterpretations of numerous spectroscopies as well in reorientational dynamics\nof water near biological and inorganic systems."
    },
    {
        "anchor": "Criteria for extensional necking instability in complex fluids and soft\n  solids. Part II imposed tensile stress and force protocols: We study the necking of a filament of complex fluid or soft solid subject to\nuniaxial tensile stretching, under conditions of constant imposed stress and\nforce, by means of linear stability analysis and nonlinear simulations. We\ndemonstrate necking to be a flow instability that is an unavoidable consequence\nof the constitutive behaviour of essentially any viscoelastic material. We\nderive criteria for the onset of necking that can be reported in terms of\ncharacteristic signatures in the shapes of the experimentally measured material\nfunctions, and that should therefore apply universally to all materials. To\nconfirm their generality, we show them to hold numerically in six constitutive\nmodels. Under conditions of constant stress, we find two distinct dynamical\nregimes as a function of time. In the first regime the strain rate quickly\nattains a value prescribed by the fluid's underlying homogeneous constitutive\ncurve, at the given stress. In this first regime, no appreciable necking\narises. A second regime then ensues in which the homogeneous flow destabilises\nto form a neck. This necking instability can occur via two distinct modes. The\nfirst mode is relatively gentle and arises in any regime where the slope of the\nconstitutive curve is positive. It has a rate of necking per accumulated strain\nunit set by the inverse of the slope of the constitutive curve. The second mode\nsets in when a carefully defined `elastic derivative' of the tensile force\nfirst slopes down as a function of the time. We discuss the way in which these\nmodes of instability manifest themselves in entangled polymeric fluids,\ndemonstrating four distinct regimes of necking behaviour as a function of\nstress. Under conditions of constant imposed force, typically the flow sweeps\nup the underlying constitutive curve of the fluid in question, with instability\nto necking in any regime where that curve is positively sloping.",
        "positive": "Electrostatics of Patchy Surfaces: In the study of colloidal, biological and electrochemical systems, it is\ncustomary to treat surfaces, macromolecules and electrodes as homogeneously\ncharged. This simplified approach is proven successful in most cases, but fails\nto describe a wide range of heterogeneously charged surfaces commonly used in\nexperiments. For example, recent experiments have revealed a long-range\nattraction between overall neutral surfaces, locally charged in a mosaic-like\nstructure of positively and negatively charged domains (\"patches\"). Here we\nreview experimental and theoretical studies addressing the stability of\nheterogeneously charged surfaces, their ionic strength in solution, and the\ninteraction between two such surfaces. We focus on electrostatics, and\nhighlight the important new physical parameters appearing in the heterogeneous\ncase, such as the largest patch size and inter-surface charge correlations"
    },
    {
        "anchor": "Suppression of Aggregation in Natural-Semiflexible/Flexible Polyanion\n  Mixtures, and Direct Check of the OSF Model using SANS: Aggregation and other interactions are suppressed for a biological\nsemiflexible polyelectrolyte, hyaluronan (HA), when it is embedded in a mixture\nwith another negatively charged and flexible polyelectrolyte chain, sodium\npolystyrene sulfonate. We see directly HA only in the mixture using Small-Angle\nNeutron Scattering, isotopic labelling and contrast matching. At low ionic\nstrength, for which aggregation is usually seen for pure HA solutions, an\nunambiguous set of experimental results shows that we neither observe HA\naggregation nor a polyelectrolyte peak (observed for solutions of single\nspecies); instead we observe a wormlike chain behaviour characteristic of\nsingle chain with a variation of the persistence length with the square of the\nDebye screening length, Le~\\kappa^-2, as formerly predicted by Odijk and not\nyet observed on a polymer chain.",
        "positive": "Depletion induced isotropic-isotropic phase separation in suspensions of\n  rod-like colloids: When non-adsorbing polymers are added to an isotropic suspension of rod-like\ncolloids, the colloids effectively attract each other via depletion forces. We\nperformed Monte Carlo simulations to study the phase diagram of such\nrod-polymer mixture. The colloidal rods were modelled as hard spherocylinders;\nthe polymers were described as spheres of the same diameter as the rods. The\npolymers may overlap with no energy cost, while overlap of polymers and rods is\nforbidden.\n  Large amounts of depletant cause phase separation of the mixture. We\nestimated the phase boundaries of isotropic-isotropic coexistence both, in the\nbulk and in confinement. To determine the phase boundaries we applied the grand\ncanonical ensemble using successive umbrella sampling [J. Chem. Phys. 120,\n10925 (2004)], and we performed a finite-size scaling analysis to estimate the\nlocation of the critical point. The results are compared with predictions of\nthe free volume theory developed by Lekkerkerker and Stroobants [Nuovo Cimento\nD 16, 949 (1994)]. We also give estimates for the interfacial tension between\nthe coexisting isotropic phases and analyse its power-law behaviour on approach\nof the critical point."
    },
    {
        "anchor": "Writhing and hockling instabilities in twisted elastic fibers: The buckling and twisting of slender, elastic fibers is a deep and\nwell-studied field. A slender elastic rod that is twisted with respect to a\nfixed end will spontaneously form a loop, or hockle, to relieve the torsional\nstress that builds. Further twisting results in the formation of plectonemes --\na helical excursion in the fiber that extends with additional twisting. Here we\nuse an idealized, micron-scale experiment to investigate the energy stored, and\nsubsequently released, by hockles and plectonemes as they are pulled apart, in\nanalogy with force spectroscopy studies of DNA and protein folding. Hysteresis\nloops in the snapping and unsnapping inform the stored energy in the twisted\nfiber structures.",
        "positive": "Morphing of Geometric Composites via Residual Swelling: Understanding and controlling the shape of thin, soft objects has been the\nfocus of significant research efforts among physicists, biologists, and\nengineers in the last decade. These studies aim to utilize advanced materials\nin novel, adaptive ways such as fabricating smart actuators or mimicking living\ntissues. Here, we present the controlled growth--like morphing of 2D sheets\ninto 3D shapes by preparing geometric composite structures that deform by\nresidual swelling. The morphing of these geometric composites is dictated by\nboth swelling and geometry, with diffusion controlling the swelling-induced\nactuation, and geometric confinement dictating the structure's deformed shape.\nBuilding on a simple mechanical analog, we present an analytical model that\nquantitatively describes how the Gaussian and mean curvatures of a thin disk\nare affected by the interplay among geometry, mechanics, and swelling. This\nmodel is in excellent agreement with our experiments and numerics. We show that\nthe dynamics of residual swelling is dictated by a competition between two\ncharacteristic diffusive length scales governed by geometry. Our results\nprovide the first 2D analog of Timoshenko's classical formula for the thermal\nbending of bimetallic beams - our generalization explains how the Gaussian\ncurvature of a 2D geometric composite is affected by geometry and elasticity.\nThe understanding conferred by these results suggests that the controlled\nshaping of geometric composites may provide a simple complement to traditional\nmanufacturing techniques."
    },
    {
        "anchor": "Frequency-dependent Ultrasonic Stimulation of PNIPAM Microgels in Water: As a novel stimulus, we used high-frequency ultrasonic waves to provide the\nrequired energy for breaking hydrogen bonds between Poly(N-isopropylacrylamide)\n(PNIPAM) and water molecules while the solution temperature maintains below the\nvolume phase transition temperature (VPTT=$$32^\\circ C$$). Ultrasonic waves\npropagate through the solution and their energy will be absorbed due to the\nliquid viscosity. The absorbed energy partially leads to the generation of a\nstreaming flow and the rest will be spent to break the hydrogen bonds.\nTherefore, the microgels collapse and become insoluble in the water and\nagglomerate, resulting in turbidity. We used turbidity to quantify the\nultrasound energy absorption and showed that the acousto-response of PNIPAM\nmicrogels is a temporal phenomenon that depends on the duration of the\nactuation. Increasing the solution concentration leads to a faster hydrogen\nbond breakage and turbidity evolution. Furthermore, the frequency of imposed\nwaves is important and affects the stimulation kinetics of PNIPAM microgels.\nIncreasing the frequency of actuation increases the speed of hydrogen bond\nbreakage and thus turbidity evolution. This is due to the increase in\nultrasound energy absorption by liquids at higher frequencies.",
        "positive": "3D model for surface accumulation of chiral and non-chiral microswimmers: Persistent motion of microswimmers near boundaries is known to result in\nsurface accumulation. Recently it was shown experimentally that surface\naccumulation of microswimmers is impacted primarily by steric forces and\nshort-ranged hydrodynamics. A way to control surface accumulation is by\nreducing the contact surface area between swimmers and surface by modifying its\ntopography, typically through the application of microscale structure. In this\nwork, we introduce a three-dimensional(3D) model of a microswimmer navigating a\nvolume bounded by a top and bottom surface. We describe the swimmer-surface\ninteraction with an effective short-ranged hydrodynamic alignment force, and\nstudy numerically the effect of surface textures, modelled by convex obstacles,\non the surface accumulation of chiral and non-chiral microswimmers. We find\nthat, depending on the angular velocity of the swimmer, and the alignment\nforce, convex obstacles can either hinder or enhance surface accumulation. We\ndiscuss potential applications to sorting of microswimmers by their angular\nvelocity."
    },
    {
        "anchor": "Micro-macro transition and simplified contact models for wet granular\n  materials: Wet granular materials in a quasi-static steady state shear flow have been\nstudied with discrete particle simulations. Macroscopic quantities, consistent\nwith the conservation laws of continuum theory, are obtained by time averaging\nand spatial coarse-graining. Initial studies involve understanding the effect\nof liquid content and liquid properties like the surface tension on the\nmacroscopic quantities. Two parameters of the liquid bridge contact model have\nbeen studied as the constitutive parameters that define the structure of this\nmodel (i) the rupture distance of the liquid bridge model, which is\nproportional to the liquid content, and (ii) the maximum adhesive force, as\ncontrolled by the surface tension of the liquid. Subsequently a correlation is\ndeveloped between these micro parameters and the steady state cohesion in the\nlimit of zero confining pressure. Furthermore, as second result, the\nmacroscopic torque measured at the walls, which is an experimentally accessible\nparameter, is predicted from our simulation results as a dependence on the\nmicro-parameters. Finally, the steady state cohesion of a realistic non-linear\nliquid bridge contact model scales well with the steady state cohesion for a\nsimpler linearized irreversible contact model with the same maximum adhesive\nforce and equal energy dissipated per contact.",
        "positive": "Collapse transition of a Lennard Jones polymer: Using the recently introduced parsimonious Metropolis algorithm bead-stick\npolymers both with infinite-range Lennard-Jones interaction and with truncation\nare simulated. The focus lays on determining the Boyle temperature for long\nchains with thousands of repeat units and on testing for theoretically\npredicted logarithmic corrections. Subsequently the behavior at the\ninfinite-chain transition temperature, i.e., the $\\Theta$-temperature is\nstudied for chains with up to $N = 32768$ repeat units by investigation of the\nscaling of the end-to-end distance, the radius of gyration, the specific heat,\nand their derivatives with $N$."
    },
    {
        "anchor": "Molecular simulation and theory of a liquid crystalline disclination\n  core: Molecular simulations of a nematic liquid crystal confined in cylinder\ngeometry with homeotropic anchoring have been carried out. The core structure\nof a disclination line defect of strength +1 has been examined, and comparison\nmade with various theoretical treatments, which are presented in a unified way.\nIt is found that excellent fits to the cylindrically-symmetrized order tensor\nprofiles may be obtained with appropriate parameter choices; notwithstanding\nthis, on the timescales of the simulation, the cylindrical symmetry of the core\nis broken and two defects of strength +1/2 may be resolved.",
        "positive": "Structure of jammed ellipse packings with a wide range of aspect ratios: Motivated in part by the recent observation of liquid glass in suspensions of\nellipsoidal colloids, we examine the structure of jammed ellipse packings over\na much wider range of particle aspect ratios ($\\alpha$) than has been\npreviously attempted. We determine $\\phi_{\\rm J}(\\alpha)$ to high precision,\nand find empirical analytic formulae that predict $\\phi_{\\rm J}(\\alpha)$ to\nwithin less than 0.1% for all $1 \\leq \\alpha \\leq 10$, for three different\nparticle dispersities. We find that the densest packings possess\nunusually-well-defined nearest-neighbor shells, including both a higher\nfraction $f_{\\rm Z = 6}$ of particles with exactly six contacts and a\npreviously-unreported short-range order marked by ``kinetically suppressed''\nregions in their positional-orientational pair correlation function $g(r,\\Delta\n\\theta)$. We also show that the previously-reported approach to isostaticity\n(coordination number $Z_{\\rm J} \\to Z_{\\rm iso} \\equiv 6$) with increasing\n$\\alpha$ is interrupted and then reversed as local nematic order increases:\n$Z_{\\rm J}(\\alpha)$ drops towards 4 as ellipses are more often trapped by\ncontacts with a parallel-oriented neighbor on either side and a\nperpendicularly-oriented neighbor on either end. Finally we show that\n$\\phi_{\\rm J}/\\phi_{\\rm s}$ (where $\\phi_{\\rm s}$ is the saturated RSA packing\ndensity) is nearly $\\alpha$-independent for systems that do not develop\nsubstantial local hexatic or nematic order during compression."
    },
    {
        "anchor": "What drives the translocation of stiff chains?: We study the dynamics of the passage of a stiff chain through a pore into a\ncell containing particles that bind reversibly to it. Using Brownian Molecular\nDynamics simulations we investigate the mean-first-passage time as a function\nof the length of the chain inside, for different concentrations of binding\nparticles. As a consequence of the interactions with these particles, the chain\nexperiences a net force along its length whose calculated value from the\nsimulations accounts for the velocity at which it enters the cell. This force\ncan in turn be obtained from the solution of a generalized diffusion equation\nincorporating an effective Langmuir adsorption free energy for the chain plus\nbinding particles. These results suggest a role of binding particles in the\ntranslocation process which is in general quite different from that of a\nBrownian ratchet. Furthermore, non-equilibrium effects contribute significantly\nto the dynamics, \\emph{e.g.}, the chain often enters the cell faster than\nparticle binding can be saturated, resulting in a force several times smaller\nthan the equilibrium value.",
        "positive": "Enzymatic AND Logic Gate with Sigmoid Response Induced by\n  Photochemically Controlled Oxidation of the Output: We report a study of a system which involves an enzymatic cascade realizing\nan AND logic gate, with an added photochemical processing of the output\nallowing to make the gate's response sigmoid in both inputs. New functional\nforms are developed for quantifying the kinetics of such systems, specifically\ndesigned to model their response in terms of signal and information processing.\nThese theoretical expressions are tested for the studied system, which also\nallows us to consider aspects of biochemical information processing such as\nnoise transmission properties and control of timing of the chemical and\nphysical steps."
    },
    {
        "anchor": "Direct tests of single-parameter aging: This paper presents accurate data for the physical aging of organic glasses\njust below the glass transition probed by monitoring the following quantities\nafter temperature up and down jumps: the shear-mechanical resonance frequency\n(around 360 kHz), the dielectric loss at 1 Hz, the real part of the dielectric\nconstant at 10 kHz, and the loss-peak frequency of the dielectric beta process\n(around 10 kHz). The setup used allows for keeping temperature constant within\n100 micro Kelvin and for thermal equilibration within a few seconds after a\ntemperature jump. The data conform to a new simplified version of the classical\nTool-Narayanaswamy aging formalism, which makes it possible to calculate one\nrelaxation curve directly from another without any fitting to analytical\nfunctions.",
        "positive": "Strong electrostatic interactions in spherical colloidal systems: We investigate spherical macroions in the strong Coulomb coupling regime\nwithin the primitive model in salt-free environment. We first show that the\nground state of an isolated colloid is naturally overcharged by simple\nelectrostatic arguments illustrated by the Gillespie rule. We furthermore\ndemonstrate that in the strong Coulomb coupling this mechanism leads to ionized\nstates and thus to long range attractions between like-charged spheres. We use\nmolecular dynamics simulations to study in detail the counterion distribution\nfor one and two highly charged colloids for the ground state as well as for\nfinite temperatures. We compare our results in terms of a simple version of a\nWigner crystal theory and find excellent qualitative and quantitative\nagreement."
    },
    {
        "anchor": "Robustness of the Fractal Regime for the Multiple-Scattering Structure\n  Factor: In the single-scattering theory of electromagnetic radiation, the {\\it\nfractal regime} is a definite range in the photon momentum-transfer $q$, which\nis characterized by the scaling-law behavior of the structure factor: $S(q)\n\\propto 1/q^{d_f}$. This allows a straightforward estimation of the fractal\ndimension $d_f$ of aggregates in {\\it Small-Angle X-ray Scattering} (SAXS)\nexperiments. However, this behavior is not commonly studied in optical\nscattering experiments because of the lack of information on its domain of\nvalidity. In the present work, we propose a definition of the\nmultiple-scattering structure factor, which naturally generalizes the\nsingle-scattering function $S(q)$. We show that the mean-field theory of\nelectromagnetic scattering provides an explicit condition to interpret the\nsignificance of multiple scattering. In this paper, we investigate and discuss\nelectromagnetic scattering by three classes of fractal aggregates. The results\nobtained from the TMatrix method show that the fractal scaling range is divided\ninto two domains: 1) a genuine fractal regime, which is robust; 2) a possible\nanomalous scaling regime, $S(q) \\propto 1/q^{\\delta}$, with exponent $\\delta$\nindependent of $d_f$, and related to the way the scattering mechanism uses the\nlocal morphology of the scatterer. The recognition, and an analysis, of the\nlatter domain is of importance because it may result in significant reduction\nof the fractal regime, and brings into question the proper mechanism in the\nbuild-up of multiple-scattering.",
        "positive": "Orientation-dependent handedness and chiral design: Chirality occupies a central role in fields ranging from biological\nself-assembly to the design of optical metamaterials. The definition of\nchirality, as given by Lord Kelvin, associates chirality with the lack of\nmirror symmetry: the inability to superpose an object on its mirror image.\nWhile this definition has guided the classification of chiral objects for over\na century, the quantification of handed phenomena based on this definition has\nproven elusive, if not impossible, as manifest in the paradox of chiral\nconnectedness. In this work, we put forward a quantification scheme in which\nthe handedness of an object depends on the direction in which it is viewed.\nWhile consistent with familiar chiral notions, such as the right-hand rule,\nthis framework allows objects to be simultaneously right and left handed. We\ndemonstrate this orientation dependence in three different systems - a\nbiomimetic elastic bilayer, a chiral propeller, and optical metamaterial - and\nfind quantitative agreement with chirality pseudotensors whose form we\nexplicitly compute. The use of this approach resolves the existing paradoxes\nand naturally enables the design of handed metamaterials from symmetry\nprinciples."
    },
    {
        "anchor": "Phase behaviour of active Brownian particles: The role of dimensionality: Recently, there has been much interest in activity-induced phase separations\nin concentrated suspensions of \"active Brownian particles\" (ABPs),\nself-propelled spherical particles whose direction of motion relaxes through\nthermal rotational diffusion. To date, almost all these studies have been\nrestricted to 2 dimensions. In this work we study activity-induced phase\nseparation in 3D and compare the results with previous and new 2D simulations.\nTo this end, we performed state-of-the-art Brownian dynamics simulations of up\nto 40 million ABPs -- such very large system sizes are unavoidable to evade\nfinite size effects in 3D. Our results confirm the picture established for 2D\nsystems in which an activity-induced phase separation occurs, with strong\nanalogies to equilibrium gas-liquid spinodal decomposition, in spite of the\npurely non-equilibrium nature of the driving force behind the phase separation.\nHowever, we also find important differences between the 2D and 3D cases.\nFirstly, the shape and position of the phase boundaries is markedly different\nfor the two cases. Secondly, for the 3D coarsening kinetics we find that the\ndomain size grows in time according to the classical diffusive $t^{1/3}$ law,\nin contrast to the nonstandard subdiffusive exponent observed in 2D.",
        "positive": "Percus-Yevick Structure Factors Made Simple: Measuring the structure factor, S(q), of a dispersion of particles by\nSmall-Angle X-ray Scattering provides a unique method to investigate the\nspatial arrangement of colloidal particles. However, it is impossible to find\nthe exact location of the particles from S(q) because some information is\ninherently lacking in the SAXS signal. The two standard ways to analyse an\nexperimental structure factor are then to compare it either to structure\nfactors computed from simulated systems, or to analytical structure factors\ncalculated from approximated systems. For liquids of monodisperse hard spheres,\nthe latter method provides analytical structure factors through the\nOrnstein-Zernike equation used with the Percus-Yevick closure equation. The\nstructure factors obtained in this way were not adequate for the more common\ndispersions of polydisperse particles. However, Vrij, Bloom and Stell were able\nto demonstrate that the same mathematical framework could be extended to yield\naccurate approximations for the experimental structure factor. Still, this\nsolution has remained underused because of its mathematical complexity. In the\npresent work, we derive and report the complete Percus-Yevick solution for\ngeneral polydisperse hard-spheres systems in a concise form that is\nstraightforward to use. The form of the solution is made simple enough to give\nready solutions of several important particle-radius distributions (Schulz,\ntruncated normal and inverse Gaussian). We also discuss in detail the case of\nthe power-law radius distribution, relevant in the case of systems made of an\nApollonian packing of spheres, as recently discovered experimentally in high\ninternal-phase-ratio emulsions."
    },
    {
        "anchor": "Elastic traits of the extensible discrete wormlike chain model: Polymer models play the special role of elucidating the elementary features\ndescribing the physics of long molecules and become essential to interpret the\nmeasurements of their magnitudes. In this work the end-to-end distance of an\nextensible discrete worm-like chain polymer as a function of the applied force\nhas been calculated both numerically and analytically, the latter as an\neffective approximation. The numerical evaluation uses the Transfer Matrix\nformalism to obtain an exact calculation of the partition function, while the\nanalytic derivations generalize the simple phenomenological formulas largely\nused up to now. The obtained formulas are simple enough to be implemented in\nthe fit analysis of experimental data of semi-flexible extensible polymers,\nwith the result that the elastic parameters obtained are compatible with\nprevious measurements, and more, their accuracy strongly improves in a large\nrange of chain extensibility.",
        "positive": "Shape-controlled orientation and assembly of colloids with sharp edges\n  in nematic liquid crystals: The assembly of colloids in nematic liquid crystals via topological defects\nhas been extensively studied for spherical particles, and investigations of\nother colloid shapes have revealed a wide array of new assembly behaviors. We\nshow, using Landau-de Gennes numerical modeling, that nematic defect\nconfigurations and colloidal assembly can be strongly influenced by fine\ndetails of colloid shape, in particular the presence of sharp edges. For\ncylinder, microbullet, and cube colloid geometries, we obtain the particles'\nequilibrium alignment directions and effective pair interaction potentials as a\nfunction of simple shape parameters. We find that defects pin at sharp edges,\nand that the colloid consequently orients at an oblique angle relative to the\nfar-field nematic director that depends on the colloid's shape. This\nshape-dependent alignment, which we confirm in experimental measurements,\nraises the possibility of selecting self-assembly outcomes for colloids in\nliquid crystals by tuning particle geometry."
    },
    {
        "anchor": "Self-Propelled Janus Colloids in Shear Flow: To fully harness the potential of artificial active colloids, investigation\nof their response to various external stimuli including external flow is of\ngreat interest. Therefore, in this study, we perform experiments on SiO2-Pt\nJanus particles suspended in an aqueous medium in a capillary subjected to\ndifferent shear flow rates. Particles were propelled using varied H2O2 (fuel)\nconcentrations. For a particular propulsion speed, with increasing shear flow,\na transition of motion of active Janus particles from the usual random active\nmotion to preferential motion across stream-lines and then finally to migration\nalong the flow, was observed. Our analysis revealed that these transitions are\ndictated by the torque due to the self-propulsion near wall w.r.t.\nshear-induced torque. Interestingly, we found that only when these torques are\ncomparable, particles align in a manner such that they migrate significantly\nacross the streamlines.",
        "positive": "Swimmers at Interfaces Enhance Interfacial Transport: The behavior of fluid interfaces far from equilibrium plays central roles in\nnature and in industry. Active swimmers trapped at interfaces can alter\ntransport at fluid boundaries with far reaching implications. Swimmers can\nbecome trapped at interfaces in diverse configurations and swim persistently in\nthese surface adhered states. The self-propelled motion of bacteria makes them\nideal model swimmers to understand such effects. We have recently characterized\nthe swimming of interfacially-trapped Pseudomonas aeruginosa PA01 moving in\npusher mode. The swimmers adsorb at the interface with pinned contact lines,\nwhich fix the angle of the cell body at the interface and constrain their\nmotion. Thus, most interfacially-trapped bacteria swim along circular paths.\nFluid interfaces form incompressible two-dimensional layers, altering leading\norder interfacial flows generated by the swimmers from those in bulk. In our\nprevious work, we have visualized the interfacial flow around a pusher\nbacterium and described the flow field using two dipolar hydrodynamic modes;\none stresslet mode whose symmetries differ from those in bulk, and another bulk\nmode unique to incompressible fluid interfaces. Based on this understanding,\nswimmers-induced tracer displacements and swimmer-swimmer pair interactions are\nexplored using analysis and experiment. The settings in which multiple\ninterfacial swimmers with circular motion can significantly enhance interfacial\ntransport of tracers or promotemixing of other swimmers on the interface are\nidentified through simulations and compared to experiment. This study\nidentifies important factors of general interest regarding swimmers on or near\nfluid boundaries, and in the design of biomimetic swimmers to enhance transport\nat interfaces"
    },
    {
        "anchor": "Fluctuations and power-law scaling of dry, frictionless granular\n  rheology near the hard-particle limit: The flow of frictionless granular particles is studied with stress-controlled\ndiscrete element modeling simulations for systems varying in size from 300 to\n100,000 particles. The volume fraction and shear stress ratio $\\mu$ are\nrelatively insensitive to system size fo a wide range of inertial numbers $I$.\nSecond-order effects in strain rate, such as second normal stress differences,\nrequire large system sizes to accurately extract meaningful results, notably a\nnon-monotonic dependence in the first normal stress difference with strain\nrate. The first-order rheological response represented by the $\\mu(I)$\nrelationship works well at describing the lower-order aspects of the rheology,\nexcept near the quasi-static limit of these stress-controlled flows. The\npressure is varied over five decades, and a pressure dependence of the\ncoordination number is observed, which is not captured by the inertial number.\nLarge fluctuations observed for small systems $N\\le$ 1,000 near the\nquasi-static limit can lead to arrest of flow resulting in challenges to\nfitting the data to rheological relationships. The inertial number is also\ninsufficient for capturing the pressure-dependent behavior of property\nfluctuations. Fluctuations in the flow and microstructural properties are\nmeasured in both the quasi-static and inertial regimes, including shear stress,\npressure, strain rate, normal stress differences, volume fraction, coordination\nnumber and contact fabric anisotropy. The fluctuations in flow properties scale\nself-similarly with pressure and system size. A transition in the scaling of\nfluctuations of stress properties and contact fabric anisotropy are measured\nand proposed as a quantitative identification of the transition from inertial\nto quasi-static flow.",
        "positive": "Waltzing route towards double-helix formation in cholesteric shells: We study cholesteric order in liquid crystal shells with planar degenerate\nanchoring. We observe that the bipolar and radial configurations intensively\nreported for bulk droplets have a higher degree of complexity when the liquid\ncrystal is confined to a spherical shell. The bipolar configuration is replaced\nby a structure where the boojums are linked to a stack of disclination rings\nthat spans the shell, while the radial configuration exhibits a double helix\nstructure where two disclinations wind around each other. Our results confirm\nrecent numerical simulations and highlight the complexity of the defect\nstructures arising when cholesteric liquid crystals are confined to spherical\ngeometries. We also show that the position of the boojums is only ruled by the\nshell geometry, independently of the cholesteric pitch. To understand\nquantitatively this behavior, we develop a simple yet insightful theoretical\nframework which captures the essence of the observed phenomenology. We also\nshow that the transition between the two configurations is solely governed by\nthe confinement ratio c = h/p, where h is the average shell thickness and p is\nthe cholesteric pitch. Finally, we perform a dynamical study of this\ntransition, and report a fascinating defect waltz due to a chemical Lehmann\neffect."
    },
    {
        "anchor": "Propagating stress waves during epithelial expansion: Coordinated motion of cell monolayers during epithelial wound healing and\ntissue morphogenesis involves mechanical stress generation. Here we propose a\nmodel for the dynamics of epithelial expansion that couples mechanical\ndeformations in the tissue to contractile activity and polarization in the\ncells. A new ingredient of our model is a feedback between local strain,\npolarization and contractility that naturally yields a mechanism for\nviscoelasticity and effective inertia in the cell monolayer. Using a\ncombination of analytical and numerical techniques, we demonstrate that our\nmodel quantitatively reproduces many experimental findings [Nat. Phys. 8, 628\n(2012)], including the build-up of intercellular stresses, and the existence of\ntraveling mechanical waves guiding the oscillatory monolayer expansion.",
        "positive": "Tuning the random walk of active colloids: Active particles such as swimming bacteria or self-propelled colloids are\nknown to spontaneously organize into fascinating large-scale dynamic\nstructures. The emergence of these collective states from the motility pattern\nof the individual particles, typically a random walk, is yet to be probed in a\nwell-defined synthetic system. Here, we report the experimental realization of\nintermittent colloidal motion that reproduces the run-and-tumble and Levy\ntrajectories common to many swimming and swarming bacteria. Our strategy\nenables to tailor the sequence of repeated \"runs\" (nearly constant-speed\nstraight-line translation) and \"tumbles\" (seemingly erratic turn) to emulate\nany random walk. This new paradigm for active locomotion at the microscale\nopens new opportunities for experimental explorations of the collective\ndynamics emerging in active suspensions. We find that population of these\nrandom walkers exhibit behaviors reminiscent of bacterial suspensions such as\ndynamic clusters and mesoscale turbulent-like flows."
    },
    {
        "anchor": "Scalar $\u03c6^4$ field theory for active-particle phase separation: Recent theories predict phase separation among orientationally disordered\nactive particles whose propulsion speed decreases rapidly enough with density.\nCoarse-grained models of this process show time-reversal symmetry (detailed\nbalance) to be restored for uniform states, but broken by gradient terms; hence\ndetailed-balance violation is strongly coupled to interfacial phenomena. To\nexplore the subtle generic physics resulting from such coupling we here\nintroduce `Active Model B'. This is a scalar $\\phi^4$ field theory (or\nphase-field model) that minimally violates detailed balance via a leading-order\nsquare-gradient term. We find that this additional term has modest effects on\ncoarsening dynamics, but alters the static phase diagram by creating a jump in\n(thermodynamic) pressure across flat interfaces. Both results are surprising,\nsince interfacial phenomena are always strongly implicated in coarsening\ndynamics but are, in detailed-balance systems, irrelevant for phase equilibria.",
        "positive": "Catastrophic thinning of dielectric elastomers: We provide a clear energetic insight into the catastrophic nature of the\nso-called creasing and pull-in instabilities in soft electro-active elastomers.\nThese phenomena are ubiquitous for thin electro-elastic plates and are a major\nobstacle to the development of giant actuators; yet they are not completely\nunderstood nor modelled accurately. Here, in complete agreement with\nexperiments, we give a simple formula to predict the voltage thresholds for\nthese instability patterns and model their shape, and show that equilibrium is\nimpossible beyond their onset. Our analysis is fully analytical, does not\nrequire finite element simulations, and can be extended to include pre-stretch\nand to encompass any material behaviour."
    },
    {
        "anchor": "Efficient Brownian Dynamics Simulation of Single DNA with Hydrodynamic\n  Interactions in Linear Flows: The coarse-grained molecular dynamics (MD) or Brownian dynamics (BD)\nsimulation is a particle-based approach that has been applied to a wide range\nof biological problems that involve interactions with surrounding fluid\nmolecules or the so-called hydrodynamic interactions (HIs). In this paper, an\nefficient algorithm is proposed to simulate the motion of a single DNA molecule\nin linear flows. The algorithm utilizes the integraing factor to cope with the\neffect of the linear flow of the surrounding fluid and applies the Metropolis\nmethod (MM) in [N. Bou-Rabee, A. Donev, and E. Vanden-Eijnden, Multiscale\nModel. Simul. 12, 781 (2014)] to achieve more efficient BD simulation. Thus our\nmethod permits much larger time step size than previous methods while still\nmaintaining the stability of the BD simulation, which is advantageous for\nlong-time BD simulation. Our numerical results on $\\lambda$-DNA agree very well\nwith both experimental data and previous simulation results. Finally, when\ncombined with fast algorithms such as the fast multipole method which has\nnearly optimal complexity in the total number of beads, the resulting method is\nparallelizable, scalable to large systems, and stable for large time step size,\nthus making the long-time large-scale BD simulation within practical reach.\nThis will be useful for the study of membranes, long-chain molecules, and a\nlarge collection of molecules in the fluids.",
        "positive": "Common Packing Patterns for Jammed Particles of Different Power Size\n  Distributions: We introduce a model for particles that are extremely polydisperse in size\ncompared to monodisperse and bidisperse systems. In two dimensions (2D), size\npolydispersity inhibits crystallization and increases packing fraction at\njamming points. However, no packing pattern common to diverse polydisperse\nparticles has been reported. We focused on polydisperse particles with a power\nsize distribution $r^{-a}$ as a ubiquitous system that can be expected to be\nscale-invariant. We experimentally and numerically constructed 2D random\npacking for various polydisperse particles with different size exponents, $a$.\nAnalysis of the packing pattern revealed a common contact number distribution\nfor $a<3$ and a higher jamming point in $2<a<3$ than monodisperse systems.\nThese findings demonstrate that the ambiguity of the characteristic length\nprovides the common properties that leads to a novel classification scheme for\npolydisperse particles."
    },
    {
        "anchor": "Dynamics of Hydrogen Bonds Coupling on the Specific DNA-Protein\n  Interactions: We propose a dynamical model depicting the interactions between DNA and a\nspecific binding protein involving long range transmissions. The dynamics rely\non the coupling between Hydrogen bonds formed between DNA and protein and\nbetween the base pairs because they account for site specificity of the\nbinding. We adopt the Morse potential with coupling terms to construct the\nHamiltonian. This model gives rise to a breather excitation, corresponding to\nthe DNA bubble formation, which propagates as the carrier of genetic\ninformation. We examine the various kind of possible coupling dynamics and\nsuggest the model feasibility in depicting the renaturation or hybridization\nprocesses.",
        "positive": "Messy or Ordered? Multi-scale Mechanics DictatesShape-Morphing of\n  Hierarchical 2D Fiber-Networks: Shape-morphing networks of mesoscale filaments are a common hierarchical\nfeature in biology and hold significant potential for a range of technological\napplications, from micro-muscles to shape-morphing optical devices. Here, we\ndemonstrate both experimentally and computationally that the shape-morphing of\nhighly-ordered 2D networks constructed of thermoresponsive mesoscale polymeric\nfibers strongly depends on the physical attributes of the single fiber, in\nparticular on its diameter, as well as on the network's density. We show that\nbased on these parameters, such fiber-networks exhibit one of two thermally\ndriven morphing behaviors: (i) the fibers stay straight, and the network\npreserves its ordered morphology, exhibiting a bulk-like behavior; or (ii) the\nfibers buckle and the network becomes messy and highly disordered. Notably, in\nboth cases, the networks display memory and regain their original ordered\nmorphology upon shrinking. This hierarchical principle, demonstrated here on a\nrange of networks, offers a new way for controlling the shape morphing of\nmaterials with mesoscale resolutions and elucidates that minute changes in the\nmesoscale structural attributes can translate to a dramatic change in the\nmorphing behaviors at the macroscale."
    },
    {
        "anchor": "Statics of polymer droplets on deformable surfaces: The equilibrium properties of polymer droplets on a soft deformable surface\nare investigated by molecular dynamics simulations of a bead-spring model. The\nsurface consists of a polymer brush with irreversibly end-tethered linear\nhomopolymer chains onto a flat solid substrate. We tune the softness of the\nsurface by varying the grafting density. Droplets are comprised of bead-spring\npolymers of various chain lengths. First, both systems, brush and polymer\nliquid, are studied independently in order to determine their static and\ndynamic properties. In particular, using a numerical implementation of an AFM\nexperiment, we measure the shear modulus of the brush surface and compare the\nresults to theoretical predictions. Then, we study the wetting behavior of\npolymer droplets with different contact angles and on substrates that differ in\nsoftness. Density profiles reveal, under certain conditions, the formation of a\nwetting ridge beneath the three-phase contact line. Cap-shaped droplets and\ncylindrical droplets are also compared to estimate the effect of the line\ntension with respect to the droplet size. Finally, the results of the\nsimulations are compared to a phenomenological free-energy calculation that\naccounts for the surface tensions and the compliance of the soft substrate.\nDepending on the surface/drop compatibility, surface softness and drop size, a\ntransition between two regimes is observed: from one where the drop surface\nenergy balances the adhesion with the surface, which is the classical\nYoung-Dupr\\'e wetting regime, to another one where a coupling occurs between\nadhesion, droplet and surface elastic energies.",
        "positive": "Symmetry, Thermodynamics and Topology in Active Matter: This article summarizes some of the open questions in the field of active\nmatter that have emerged during Active20, a nine-week program held at the Kavli\nInstitute for Theoretical Physics (KITP) in Spring 2020. The article does not\nprovide a review of the field, but rather a personal view of the authors,\ninformed by contributions of all participants, on new directions in active\nmatter research. The topics highlighted include: the ubiquitous occurrence of\nspontaneous flows and active turbulence and the theoretical and experimental\nchallenges associated with controlling and harnessing such flows; the role of\nmotile topological defects in ordered states of active matter and their\npossible biological relevance; the emergence of non-reciprocal effective\ninteractions and the role of chirality in active systems and their intriguing\nconnections to non-Hermitian quantum mechanics; the progress towards a\nformulation of the thermodynamics of active systems thanks to the feedback\nbetween theory and experiments; the impact of the active matter framework on\nour understanding of the emergent mechanics of biological tissue. These\nseemingly diverse phenomena all stem from the defining property of active\nmatter - assemblies of self-driven entities that individually break\ntime-reversal symmetry and collectively organize in a rich variety of\nnonequilibrium states."
    },
    {
        "anchor": "1D roughness driven depinning of breath figures on PDMS: The influence of surface constraints on the self-assembly of liquid droplets\nis investigated. A semi-quantitative explanation for large scale pattern\nformation consisting of small scale closely arranged droplets inside the large\nscale distorted ring of droplets is presented in this paper. The scale at which\nthe influence of constraints become dominant is also determined in this study.\nIt is seen that the underlying roughness has a larger impact than the nature of\npolymer on pore size. Comparative studies of pore patterns formed on smooth and\nconstrained substrates are reported. The simulated energy minimized shape of\nthe droplets on smooth and constrained substrates are obtained using\n\\textit{Surface Evolver}.",
        "positive": "Tunable Brownian Vortex at the Interface: A general kind of Brownian vortexes are demonstrated by applying an external\nnonconservative force field to a colloidal particle bound by a conservative\noptical trapping force at a liquid-air interface. As the liquid medium is\ntranslated at a constant velocity with the bead trapped at the interface, the\ndrag force near the surface provide enough rotational component to bias the\nparticle's thermal fluctuations in a circulatory motion. The interplay between\nthe thermal fluctuations and the advection of the bead in constituting the\nvortex motions is studied, inferring that the angular velocity of the\ncirculatory motion offers a comparative measure of the interface fluctuations."
    },
    {
        "anchor": "Numerical Estimation of Frictional Torques with Rate and State Friction: In this paper, numerical estimation of frictional torques is carried out of a\nrotary elastic disc on a hard and rough surface under different rotating\nconditions. A one dimensional spring- mass rotary system is numerically solved\nunder the quasistatic condition with the rate and state dependent friction\nmodel. It is established that torque of frictional strength as well as torque\nof steady dynamic stress increases with radius and found to be maximum at the\nperiphery of the disc. Torque corresponding to frictional strength estimated\nusing the analytical solution matches closely with the simulation only in the\ncase of high stiffness of the connecting spring. In steady relaxation\nsimulation, a steadily rotating disc is suddenly stopped and relaxational\nangular velocity and corresponding frictional torque decreases with both steady\nangular velocity and stiffness of the connecting spring in the velocity\nstrengthening regime. In velocity weakening regime, in contrast, torque of\nrelaxation stress deceases but relaxation velocity increases. The reason for\nthe contradiction is explained.",
        "positive": "Friction at Soft Polymer Surfaces: Lubrication Effect of Oil\n  Impregnation: The modes of attachments, detachments and relaxations of molecules of rubbers\nand gels on solid surfaces are keys to understanding their frictional\nproperties. An early stochastic model of polymer relaxations on surfaces was\ngiven by Schallamach, which has now evolved in various ways. A review of these\ndevelopments is presented along with the experimental data that elucidate the\nkinetic friction of smooth rubber against smooth surfaces. These soft rubbers\nexhibit various types of instabilities while sliding on surfaces. A few\nexamples of these instabilities are provided."
    },
    {
        "anchor": "Effect of an impulsive force on vortices in a rotating Bose-Einstein\n  condensate: The effects of a sudden increase and decrease of the interatomic interaction\nand harmonic-oscillator trapping potential on vortices in a quasi\ntwo-dimensional rotating Bose-Einstein condensate are investigated using the\nmean-field Gross-Pitaevskii equation. Upon increasing the strength of\ninteraction suddenly the condensate enters a nonstationary oscillating phase\nwhich starts to develop more vortices. The opposite happens if the strength is\nreduced suddenly. Eventually, the number of vortices attains a final value at\nlarge times. Similarly, the number of vortices increases (decreases) upon a\nsudden reduction (augmentation) in the trapping potential. We also study the\ndecay of vortices when the rotation of the condensate is suddenly stopped. Upon\na free expansion of a rotating BEC with vortices the radius of the vortex core\nincreases more rapidly than the radius of the condensate. This makes the\ncounting and detection of multiple vortex easier after a free expansion.",
        "positive": "Freezing and re-entrant melting of hard discs in a one-dimensional\n  potential:\\\\ Predictions based on a pressure-balance equation: We investigate theoretically the freezing behaviour of a two-dimensional (2D)\nsystem of hard discs on a one-dimensional (1D) external potential (typically\ncalled laser-induced freezing). As shown by earlier theoretical and numerical\nstudies, one observes freezing of the modulated liquid upon increase of the\nsubstrate potential amplitude, and re-entrant melting back into the modulated\nliquid when the substrate potential amplitude is increased even further. The\npurpose of our present work is to calculate the freezing and re-entrant melting\nphase diagram based on information from the bulk system. To this end, we employ\nan integrated pressure-balance equation derived from density functional theory\n[Phys. Rev. E \\textbf{101}, 012609 (2020)]. Furthermore, we define a measure to\nquantify the influence of registration effects that qualitatively explain\nre-entrant melting. Despite severe approximations, the calculated phase diagram\nshows good agreement with the known phase diagram obtained by Monte Carlo\nsimulations."
    },
    {
        "anchor": "Accurate coarse-grained models for mixtures of colloids and linear\n  polymers under good-solvent conditions: A coarse-graining strategy, previously developed for polymer solutions, is\nextended here to mixtures of linear polymers and hard-sphere colloids. In this\napproach groups of monomers are mapped onto a single pseudoatom (a blob) and\nthe effective blob-blob interactions are obtained by requiring the model to\nreproduce some large-scale structural properties in the zero-density limit. We\nshow that an accurate parametrization of the polymer-colloid interactions is\nobtained by simply introducing pair potentials between blobs and colloids. For\nthe coarse-grained model in which polymers are modelled as four-blob chains\n(tetramers), the pair potentials are determined by means of the iterative\nBoltzmann inversion scheme, taking full-monomer pair correlation functions at\nzero-density as targets. For a larger number $n$ of blobs, pair potentials are\ndetermined by using a simple transferability assumption based on the polymer\nself-similarity. We validate the model by comparing its predictions with\nfull-monomer results for the interfacial properties of polymer solutions in the\npresence of a single colloid and for thermodynamic and structural properties in\nthe homogeneous phase at finite polymer and colloid density. The tetramer model\nis quite accurate for $q\\lesssim 1$ ($q=\\hat{R}_g/R_c$, where $\\hat{R}_g$ is\nthe zero-density polymer radius of gyration and $R_c$ is the colloid radius)\nand reasonably good also for $q=2$. For $q=2$ an accurate coarse-grained\ndescription is obtained by using the $n=10$ blob model. We also compare our\nresults with those obtained by using single-blob models with state-dependent\npotentials.",
        "positive": "Numerical simulation of turbulent sediment transport, from bed load to\n  saltation: Sediment transport is studied as a function of the grain to fluid density\nratio using two phase numerical sim- ulations based on a discrete element\nmethod (DEM) for particles coupled to a continuum Reynolds averaged description\nof hydrodynamics. At a density ratio close to unity (typically under water),\nvertical velocities are so small that sediment transport occurs in a thin layer\nat the surface of the static bed, and is called bed load. Steady, or\n'saturated' transport is reached when the fluid borne shear stress at the\ninterface between the mobile grains and the static grains is reduced to its\nthreshold value. The number of grains transported per unit surface is therefore\nlimited by the flux of horizontal momentum towards the surface. However, the\nfluid velocity in the transport layer remains almost undisturbed so that the\nmean grain velocity scales with the shear velocity u\\ast. At large density\nratio (typically in air), the vertical velocities are large enough to make the\ntransport layer wide and dilute. Sediment transport is then called saltation.\nIn this case, particles are able to eject others when they collide with the\ngranular bed, a process called splash. The number of grains transported per\nunit surface is selected by the balance between erosion and deposition and\nsaturation is reached when one grain is statistically replaced by exactly one\ngrain after a collision, which has the consequence that the mean grain velocity\nremains independent of u\\ast. The influence of the density ratio is\nsystematically studied to reveal the transition between these two transport\nregimes. Based on the mechanisms identified in the steady case, we discuss the\ntransient of saturation of sediment transport and in particular the saturation\ntime and length. Finally, we investigate the exchange of particles between the\nmobile and static phases and we determine the exchange time of particles."
    },
    {
        "anchor": "Deformation of Silica Aerogel During Fluid Adsorption: Aerogels are very compliant materials - even small stresses can lead to large\ndeformations. In this paper we present measurements of the linear deformation\nof high porosity aerogels during adsorption of low surface tension fluids,\nperformed using a Linear Variable Differential Transformer (LVDT). We show that\nthe degree of deformation of the aerogel during capillary condensation scales\nwith the surface tension, and extract the bulk modulus of the gel from the\ndata. Furthermore we suggest limits on safe temperatures for filling and\nemptying low density aerogels with helium.",
        "positive": "The origin of dynamic scaling in dilute polymer solutions: The hydrodynamic radius of a polymer chain, obtained using Brownian dynamics\nsimulations of the continuum Edwards model, is found to obey a crossover in the\nexcluded volume parameter z, which is significantly different from that\nobserved for the radius of gyration. It is shown that this difference arises\nfrom contributions due to dynamic correlations to the diffusivity, which are\nignored in the commonly used definition of hydrodynamic radius based on the\nKirkwood expression. The swelling of the hydrodynamic radius from the\ntheta-state, obtained from simulations, shows remarkable agreement with\nexperimental measurements."
    },
    {
        "anchor": "Isomorphs in sheared binary Lennard-Jones glass: Transient response: We have studied shear deformation of binary Lennard-Jones glasses to\ninvestigate the extent to which the transient part of the stress strain curves\nis invariant when the thermodynamic state point is varied along an isomorph.\nShear deformations were carried out on glass samples of varying stability,\ndetermined by cooling rate, and at varying strain rates, at a state point deep\nin the glass. Density changes up to and exceeding a factor of two were made. We\ninvestigated several different methods for generating isomorphs but none of the\npreviously developed methods could generate sufficiently precise isomorphs\ngiven the large density changes and non-equilibrium situation. Instead, the\ntemperatures for these higher densities were chosen to give state points\nisomorphic to the starting state point by requiring the steady state flow\nstress for isomorphic state points to be invariant in reduced units. In\ncontrast to the steady state flow stress, we find that the peak stress on the\nstress strain curve is not invariant. The peak stress decreases by a few\npercent for each ten percent increase in density, although the differences\ndecrease with increasing density. Analysis of strain profiles and non-affine\nmotion during the transient phase suggests that the root of the changes in peak\nstress is a varying tendency to form shear bands, with the largest tendency\noccurring at the lowest densities. We argue that this reflects the effective\nsteepness of the potential; a higher effective steepness gives a greater\ntendency to form shear bands.",
        "positive": "Photoelastic force measurements in granular materials: Photoelastic techniques are used to make both qualitative and quantitative\nmeasurements of the forces within idealized granular materials. The method is\nbased on placing a birefringent granular material between a pair of polarizing\nfilters, so that each region of the material rotates the polarization of light\naccording to the amount of local of stress. In this review paper, we summarize\npast work using the technique, describe the optics underlying the technique,\nand illustrate how it can be used to quantitatively determine the vector\ncontact forces between particles in a 2D granular system. We provide a\ndescription of software resources available to perform this task, as well as\nkey techniques and resources for building an experimental apparatus."
    },
    {
        "anchor": "Ultrafast photomechanical transduction through thermophoretic implosion: Since the historical experiments of Crookes, the direct manipulation of\nmatter by light has been both a challenge and a source of scientific debate.\nHere we show that laser illumination allows to displace a vial of nanoparticle\nsolution over centimetre-scale distances. Cantilever-based force measurements\nshow that the movement is due to millisecond long force spikes, which are\nsynchronised with a sound emission. We observe that the nanoparticles undergo\nnegative thermophoresis, while ultrafast imaging reveals that the force spikes\nare followed by the explosive growth of a bubble in the solution. We propose a\nmechanism accounting for the propulsion based on a thermophoretic instability\nof the nanoparticle cloud, analogous to the Jeans instability that occurs in\ngravitational systems. Our experiments demonstrate a new type of laser\npropulsion, and a remarkably violent actuation of soft matter, reminiscent of\nthe strategy used by certain plants to propel their spores.",
        "positive": "Osmotic pressure of compressed lattice knots: A numerical simulation shows that the osmotic pressure of compressed lattice\nknots is a function of knot type, and so of entanglements. The osmotic pressure\nfor the unknot goes through a negative minimum at low concentrations, but in\nthe case of non-trivial knot types $3_1$ and $4_1$ it is negative for low\nconcentrations. At high concentrations the osmotic pressure is divergent, as\npredicted by Flory-Huggins theory. The numerical results show that each knot\ntype has an equilibrium length where the osmotic pressure for monomers to\nmigrate into or our of the lattice knot is zero. Moreover, the lattice unknot\nis found to have two equilibria, one unstable, and one stable, whereas the\nlattice knots of type $3_1$ and $4_1$ have one stable equilibrium each."
    },
    {
        "anchor": "Nonlinear modulation of transverse dust lattice waves in complex plasma\n  crystals: The occurrence of the modulational instability (MI) in transverse dust\nlattice waves propagating in a one-dimensional dusty plasma crystal is\ninvestigated. The amplitude modulation mechanism, which is related to the\nintrinsic nonlinearity of the sheath electric field, is shown to destabilize\nthe carrier wave under certain conditions, possibly leading to the formation of\nlocalized envelope excitations. Explicit expressions for the instability growth\nrate and threshold are presented and discussed.",
        "positive": "Investigating the normal and tangential peeling behaviour of gecko\n  spatulae using a coupled adhesion-friction model: The present work investigates the normal and tangential peeling behaviour of\na gecko spatula using a coupled adhesion-friction model. The objective is to\nexplain the strong attachment and easy detachment behaviour of the spatulae as\nwell as to understand the principles behind their optimum design. Using\nnonlinear finite element computations, it is shown that during\ntangentially-constrained peeling the partial sliding of the spatula pad near\nthe peeling front stretches the spatula, thus increasing the strain energy and\nleading to high pull-off forces. The model is used to investigate the influence\nof various parameters on the pull-off forces -- such as the peeling angle,\nspatula shaft angle, strip thickness, and material stiffness. The model shows\nthat increasing the spatula pad thickness beyond a certain level does not lead\nto a significant increase in the attachment forces. Further, the easy\ndetachment behaviour of geckos is studied under tangentially-free peeling\nconditions. It is found that the spatulae readily detach from the substrate by\nchanging their shaft angle and eventually peel vertically like a tape. Since\nthe present computational model is not limited by the geometrical, kinematical,\nand material restrictions of theoretical models, it can be employed to analyse\nsimilar biological adhesive systems."
    },
    {
        "anchor": "Membrane-protein interactions hold the key to understanding amyloid\n  formation: In this perspective we describe the critical role membranes play in\nmodulating the structures of the Amyloid Precursor Proteins to produce the\npeptides involved in the Alzheimer's disease. Some of the key concepts related\nto protein aggregation including the potential role of the excited states of\nmonomers in initiating protein aggregation are described.",
        "positive": "Stability of interlocked self-propelled dumbbell clusters: Combining experimental observations of Quincke roller clusters with computer\nsimulations and a stability analysis, we explore the formation and stability of\ntwo interlocked self-propelled dumbbells. For large self-propulsion and\nsignificant geometric interlocking, there is a stable joint spinning motion of\ntwo dumbbells. The spinning frequency can be tuned by the self-propulsion speed\nof a single dumbbell, which is controlled by an external electric field for the\nexperiments. For typical experimental parameters the rotating pair is stable\nwith respect to thermal fluctuations but hydrodynamic interactions due to the\nrolling motion of neighboring dumbbells leads to a break-up of the pair. Our\nresults provide a general insight into the stability of spinning active\ncolloidal molecules which are geometrically locked."
    },
    {
        "anchor": "A doubly associated reference perturbation theory for water: In this work we develop a new classical perturbation theory for water which\nincorporates the transition to tetrahedral symmetry in both the dispersion and\nhydrogen bonding contributions to the free energy. This transition is\ncalculated self-consistently using Wertheim's thermodynamic perturbation\ntheory. However, since the reference fluid structure to the hydrogen bonding\ntheory itself depends on hydrogen bonding, the theory represents an approach\nwhich goes beyond perturbation theory. The theory is shown to accurately\nrepresent the thermodynamics of pure water. It is demonstrated that the new\ntheory can reproduce the anomalous density maximum as well as minima in the\nisothermal compressibility and isobaric heat capacity.",
        "positive": "Locomotion of Active Sheets Driven by Curvature Modulation: The locomotion of flexible membrane-like organisms on top of curved surfaces\nappears in different contexts and scales. Still, such dynamics have not yet\nbeen quantitatively modeled and no realization of such motion in manmade\nsystems has been achieved. We present an experimental and theoretical study of\nactive gel ribbons surfing on a curved fluid-fluid interface via periodic\nmodulation of their reference curvature. We derive a theoretical model, in\nwhich forces and torques emerge from curvature mismatch between the ribbon and\nthe substrate. Analytic and numerical solutions of the equations of motion\nsuccessfully predict the experimentally measured velocity profiles. We conclude\nby highlighting the relevance of this new, curvature-driven, mode of locomotion\nfor a broad range of mechanical, as well as biological systems."
    },
    {
        "anchor": "Spin and velocity correlations in a confined two-dimensional fluid of\n  disk-shaped active rotors: We study the velocity autocorrelations in an experimental configuration of\nconfined two-dimensional active rotors (disks). We report persistent small\nscale oscillations in both rotational and translational velocity\nautocorrelations, with their characteristic frequency increasing as rotational\nactivity increases. While these small oscillations are qualitatively similar in\nall experiments, we found that, at strong particle rotational activity, the\nlarge scale particle spin fluctuations tend to vanish, with the small\noscillations around zero persisting in this case, and spins remain\npredominantly and strongly anti-correlated at longer times. For weaker\nrotational activity, however, spin fluctuations become increasingly larger and\nangular velocities remain de-correlated at longer times. We discuss in detail\nhow the autocorrelation oscillations are related to the rotational activity and\nwhy this feature is generically a signal of the emergence of chirality in the\ndynamics of a particulate system.",
        "positive": "Start-up Shear of Concentrated Colloidal Hard Spheres: Stresses,\n  Dynamics and Structure: The transient response of model hard sphere glasses is examined during the\napplication of steady rate start-up shear using Brownian Dynamics (BD)\nsimulations, experimental rheology and confocal microscopy. With increasing\nstrain the glass initially exhibits an almost linear elastic stress increase, a\nstress peak at the yield point and then reaches a constant steady state. The\nstress overshoot has a non-monotonic dependence with Peclet number, Pe, and\nvolume fraction, {\\phi}, determined by the available free volume and a\ncompetition between structural relaxation and shear advection. Examination of\nthe structural properties under shear revealed an increasing anisotropic radial\ndistribution function, g(r), mostly in the velocity - gradient (xy) plane,\nwhich decreases after the stress peak with considerable anisotropy remaining in\nthe steady-state. Low rates minimally distort the structure, while high rates\nshow distortion with signatures of transient elongation. As a mechanism of\nstoring energy, particles are trapped within a cage distorted more than\nBrownian relaxation allows, while at larger strains, stresses are relaxed as\nparticles are forced out of the cage due to advection. Even in the steady\nstate, intermediate super diffusion is observed at high rates and is a\nsignature of the continuous breaking and reformation of cages under shear."
    },
    {
        "anchor": "Structural, Rheological and Dynamic Aspects of Hydrogen-Bonding\n  Molecular Liquids: Aqueous Solutions of Hydrotropic tert-Butyl Alcohol: Hypothesis: The structural details, viscosity trends and dynamic phenomena in\nt-butanol/water solutions are closely related on the molecular scales across\nthe entire composition range. Utilizing the experimental small- and wide-angle\nx-ray scattering (SWAXS) method, molecular dynamics (MD) simulations and the\ncomplemented-system approach method developed in our group it is possible to\ncomprehensively describe the structure-viscosity-dynamics relationship in such\nstructurally versatile hydrogen-bonded molecular liquids, as well as in\nsimilar, self-assembling systems with pronounced molecular and supramolecular\nstructures at the intra-, inter-, and supra-molecular scales.\n  Experiments: The SWAXS and x-ray diffraction experiments and MD simulations\nwere performed for aqueous t-butanol solutions at 25 {\\deg}C. Literature\nviscosity and self-diffusion data were also used.\n  Findings: The interpretive power of the proposed scheme was demonstrated by\nthe extensive and diverse results obtained for aqueous t-butanol solutions\nacross the whole concentration range. Four composition ranges with\nqualitatively different structures and viscosity trends were revealed. The\nexperimental and calculated zero-shear viscosities and molecular self-diffusion\ncoefficients were successfully related to the corresponding structural details.\nThe hydrogen bonds, that were, along with hydrophobic effects, recognized as\nthe most important driving force for the formation of t-butanol aggregates,\nshow intriguing lifetime trends and thermodynamic properties of their\nformation.",
        "positive": "Fluid flow at the interface between elastic solids with randomly rough\n  surfaces: I study fluid flow at the interface between elastic solids with randomly\nrough surfaces. I use the contact mechanics model of Persson to take into\naccount the elastic interaction between the solid walls and the Bruggeman\neffective medium theory to account for the influence of the disorder on the\nfluid flow. I calculate the flow tensor which determines the pressure flow\nfactor and, e.g., the leak-rate of static seals. I show how the perturbation\ntreatment of Tripp can be extended to arbitrary order in the ratio between the\nroot-mean-square roughness amplitude and the average interfacial surface\nseparation. I introduce a matrix D(Zeta), determined by the surface roughness\npower spectrum, which can be used to describe the anisotropy of the surface at\nany magnification Zeta. I present results for the asymmetry factor Gamma(Zeta)\n(generalized Peklenik number) for grinded steel and sandblasted PMMA surfaces."
    },
    {
        "anchor": "Adsorption Kinetics of a Single Polymer on a Solid Plane: We study analytically and by means of an off-lattice bead-spring dynamic\nMonte Carlo simulation model the adsorption kinetics of a single macromolecule\non a structureless flat substrate in the regime of strong physisorption. The\nunderlying notion of a ``stem-flower'' polymer conformation, and the related\nmechanism of ``zipping'' during the adsorption process are shown to lead to a\nFokker-Planck equation with reflecting boundary conditions for the\ntime-dependent probability distribution function (PDF) of the number of\nadsorbed monomers. The theoretical treatment predicts that the mean fraction of\nadsorbed segments grows with time as a power law with a power of $(1+\\nu)^{-1}$\nwhere $\\nu\\approx 3/5$ is the Flory exponent. The instantaneous distribution of\ntrain lengths is predicted to follow an exponential relationship. The\ncorresponding PDFs for loops and tails are also derived. The complete solution\nfor the time-dependent PDF of the number of adsorbed monomers is obtained\nnumerically from the set of discrete coupled differential equations and shown\nto be in perfect agreement with the Monte Carlo simulation results. In addition\nto homopolymer adsorption, we study also regular multiblock copolymers and\nrandom copolymers, and demonstrate that their adsorption kinetics may be\nconsidered within the same theoretical model.",
        "positive": "Motor-free contractility of active biopolymer networks: Contractility in animal cells is often generated by molecular motors such as\nmyosin, which require polar substrates for their function. Motivated by recent\nexperimental evidence of motor-independent contractility, we propose a robust\nmotor-free mechanism that can generate contraction in biopolymer networks\nwithout the need for substrate polarity. We show that contractility is a\nnatural consequence of active binding/unbinding of crosslinkers that breaks the\nPrinciple of Detailed Balance, together with the asymmetric force-extension\nresponse of semiflexible biopolymers. We calculate the resulting contractile\nvelocity using both a simple coarse-grained model and a more detailed\nmicroscopic model for a viscoelastic biopolymer network. Our model may provide\nan explanation of recent reports of motor-independent contractility in cells.\nOur results also suggest a mechanism for generating contractile forces in\nsynthetic active materials."
    },
    {
        "anchor": "Perturbations of planar interfaces in Ginzburg-Landau models: Certain dissipative Ginzburg-Landau models predict existence of planar\ninterfaces moving with constant velocity. In most cases the interface solutions\nare hard to obtain because pertinent evolution equations are nonlinear. We\npresent a systematic perturbative expansion which allows us to compute effects\nof small terms added to the free energy functional of a soluble model. As an\nexample, we take the exactly soluble model with single order parameter $\\phi$\nand the potential $V_0(\\phi) = A\\phi^2 + B \\phi^3 + \\phi^4$, and we perturb it\nby adding $V_1(\\phi) = {1/2} \\epsilon_1 \\phi^2 \\partial_i \\phi \\partial_i \\phi\n+ 1/5 \\epsilon_2 \\phi^5 + 1/6 \\epsilon_3 \\phi^6. $ We discuss the corresponding\nchanges of the velocity of the planar interface.",
        "positive": "Metallurgy of soft spheres with hard core: from BCC to Frank-Kasper\n  phases: Understanding how soft particles can fill the space is still an open\nquestion. Structures far from classical FCC or BCC phases are now commonly\nexperimentally observed in many different systems. Models based on pair\ninteraction between soft particle are at present much studied in 2D. Pair\ninteraction with two different lengths have been shown to lead to\nquasicrystalline architectures. It is also the case for a hard core with a\nsquare repulsive shoulder potential. In 3D, global approaches have been\nproposed for instance by minimizing the interface area between the deformed\nobjects in the case of foams or micellar systems or using self-consistent mean\nfield theory in copolymer melts. In this paper we propose to compare a strong\nvan der Waals attraction between spherical hard cores and an elastic energy\nassociated to the deformation of the soft corona. This deformation is measured\nas the shift between the deformed shell compared to a corona with a perfect\nspherical symmetry. The two main parameters in this model are: the hard core\nvolume fraction and the weight of the elastic energy compared to the van der\nWaals one. The elastic energy clearly favours the BCC structure but large van\nder Waals forces favors Frank and Kasper phases. This result opens a route\ntowards controlling the building of nanoparticle superlattices with complex\nstructures and thus original physical properties."
    },
    {
        "anchor": "Randomly branching $\u03b8$-polymers in two and three dimensions:\n  Average properties and distribution functions: Motivated by renewed interest in the physics of branched polymers, we present\nhere a complete characterization of the connectivity and spatial properties of\n$2$ and $3$-dimensional single-chain conformations of randomly branching\npolymers in $\\theta$-solvent conditions obtained by Monte Carlo computer\nsimulations. The first part of the work focuses on polymer average properties,\nlike the average polymer spatial size as a function of the total tree mass and\nthe typical length of the average path length on the polymer backbone. In the\nsecond part, we move beyond average chain behavior and we discuss the complete\ndistribution functions for tree paths and tree spatial distances, which are\nshown to obey the classical Redner-des Cloizeaux functional form. Our results\nwere rationalized first by the systematic comparison to a Flory theory for\nbranching polymers and, next, by generalized Fisher-Pincus relationships\nbetween scaling exponents of distribution functions. For completeness, the\nproperties of $\\theta$-polymers were compared to their ideal (i.e.), no volume\ninteractions) as well as good-solvent (i.e.), above the $\\theta$-point)\ncounterparts. The results presented here brings to conclusion the recent work\nperformed in our group [A. Rosa and R. Everaers, J. Phys. A: Math. Theor. 49,\n345001 (2016), J. Chem. Phys. 145, 164906 (2016), Phys. Rev. E 95, 012117\n(2017)] in the context of the scaling properties of branching polymers.",
        "positive": "Viscoelasticity of model surfactant solutions determined by rotational\n  magnetic spectroscopy: Being able to reduce the size of a rheometer down to the micron scale is a\nunique opportunity to explore the mechanical response of expensive and/or\nconfined liquids and gels. To this aim, we synthesize micron size wires with\nmagnetic properties and examine the possibility of using them as microrheology\nprobes. In this work, we exploit the technique of rotational magnetic\nspectroscopy by placing a wire in a rotating magnetic field and monitor its\ntemporal evolution by time-lapse microscopy. The wire-based microrheology\ntechnique is tested on wormlike micellar surfactant solutions showing very\ndifferent relaxation dynamics and viscosities. A model for the wire rotation is\nalso developed and used to predict the wire behavior. It is shown that the\nrheological parameters of the surfactant solutions including the static shear\nviscosity, the entangled micellar network relaxation time and the elastic\nmodulus are in good agreement with those of conventional rheometry."
    },
    {
        "anchor": "Experimental Accessibility of Generalized Fluctuation-Dissipation\n  Relations for Nonequilibrium Steady States: We study the fluctuation-dissipation theorem for a Brownian particle driven\ninto a nonequilibrium steady state experimentally. We validate two different\ntheoretical variants of a generalized fluctuation-dissipation theorem.\nFurthermore, we demonstrate that the choice of variables crucially affects the\naccuracy of determining the nonequilibrium response from steady state\nnonequilibrium fluctuations.",
        "positive": "Formation of a transient amorphous solid in low density aqueous charged\n  sphere suspensions: Colloidal glasses form from hard spheres, nearly hard spheres, ellipsoids and\nplatelets or their attractive variants have been studied in detail.\nComplementing and checking theoretical approaches and simulations, the many\ndifferent types of model systems have significantly advanced our understanding\nof the glass transition in general. Despite their early prediction, however, no\nexperimental charged sphere glasses have been found at low density, where the\ncompeting process of crystallization prevails. We here report the formation of\na transient amorphous solid formed from charged polymer spheres suspended in\nthoroughly deionized water at volume fractions of 0.0002-0.01. From optical\nexperiments, we observe the presence of short-range order and an enhanced shear\nrigidity as compared to the stable polycrystalline solid of body centred cubic\nstructure. On a density dependent time scale of hours to days, the amorphous\nsolid transforms into this stable structure. We further present preliminary\ndynamic light scattering data showing the evolution of a second slow relaxation\nprocess possibly pointing to a dynamic heterogeneity known from other colloidal\nglasses and gels.We compare our findings to the predicted phase behaviour of\ncharged sphere suspensions and discuss possible mechanisms for the formation of\nthis peculiar type of colloidal glass."
    },
    {
        "anchor": "Electrorheological suspensions of laponite in oil: rheometry studies\n  under steady shear: We have studied the effect of an external DC electric field (~kV/mm) on the\nrheological properties of colloidal suspensions consisting of aggregates of\nlaponite particles in a silicone oil. Microscopy observations show that under\napplication of an electric field greater than a triggering electric field\nE_c~0.6 kV/mm, laponite aggregates assemble into chain- and/or column-like\nstructures in the oil. Without an applied electric field, the steady state\nshear behavior of such suspensions is Newtonian-like. Under application of an\nelectric field larger than E_c, it changes dramatically as a result of the\nchanges in the microstructure: a significant yield stress is measured, and\nunder continuous shear the fluid is shear-thinning. The rheological properties,\nin particular the dynamic and static shear stress, were studied as a function\nof particle volume fraction, for various strengths(including null) of the\napplied electric field. The flow curves under continuous shearing can be scaled\nwith respect to both particle fraction and electric field strength, onto a\nmaster curve. This scaling is consistent with simple scaling arguments. The\nshape of the master curve accounts for the system's complexity; it approaches a\nstandard Herschel-Bulkley model at high Manson numbers. Both dynamic and static\nyield stress are observed to depend on the particle fraction \\phi and electric\nfield E as \\phi^\\beta E^\\alpha, with \\alpha~1.85, and \\beta~1 and 1.70, for the\ndynamic and static yield stresses, respectively. The measured yield stress\nbehavior may be explained in terms of standard conduction models for\nelectrorheological systems. Interesting prospects include using such systems\nfor self-guided assembly of clay nano-particles.",
        "positive": "Dynamics of crater formations in immersed granular materials: We report the formation of a crater at the free surface of an immersed\ngranular bed,locally crossed by an ascending gas flow. In two dimensions, the\ncrater consists of two piles which develop around the location of the gas\nemission. We observe that the typical size of the crater increases\nlogarithmically with time, independently of the gas emission dynamics. We\ndescribe the related granular flows and give an account of the influence of the\nexperimental parameters, especially of the grain size and of the gas flow."
    },
    {
        "anchor": "The twist-bend nematic phase of bent mesogenic dimer CB7CB and its\n  mixtures: Binary mixtures of the twist-bend nematic-forming liquid crystal CB7CB with\nthe prototypical rod-like liquid crystal 5CB exhibit a twist-bend nematic phase\nwith properties similar to those reported for neat CB7CB. The mixtures appear\nhomogeneous, with no micron- or nano-scale segregation evident at any\nconcentration. The linear dependence of the phase transition temperature on\nconcentration indicates that these binary mixtures are nearly ideal. However, a\ndecrease in the viscosity with the addition of 5CB allows the characteristic\ntwist-bend stripe textures to relax into a state of uniform birefringence. We\nconfirm the presence of nanoscale modulations of the molecular orientation in\nthe mixtures by freeze-fracture transmission electron microscopy (FFTEM),\nfurther evidence of their twist-bend nature. We devise and implement a\nstatistical approach to quantitatively measure the ground state pitch of the\ntwist-bend phase and its mixtures using FFTEM. The addition of 5CB generally\nshifts the measured ground-state pitch distributions towards larger pitch.\nInterestingly, the pitch appears to increase discontinuously by ~10 nm at the\n50 wt% concentration of 5CB, indicating that the twist-bend phase undergoes a\nstructural transition at higher 5CB concentrations.",
        "positive": "Attractive carbon black dispersions: structural and mechanical responses\n  to shear: The rheological behavior of colloidal dispersions is of paramount importance\nin a wide range of applications, including construction materials, energy\nstorage systems and food industry products. These dispersions consistently\nexhibit non-Newtonian behaviors, a consequence of intricate interplays\ninvolving colloids morphology, volume fraction, and inter-particle forces.\nUnderstanding how colloids structure under flow remains a challenge,\nparticularly in the presence of attractive forces leading to clusters\nformation. In this study, we adopt a synergistic approach, combining rheology\nwith ultra small-angle X-ray scattering (USAXS), to probe the flow-induced\nstructural transformations of attractive carbon black (CB) dispersions and\ntheir effects on the viscosity. Our key findings can be summarized as follow.\nFirst, testing different CB volume fractions, in the high shear rate\nhydrodynamic regime, CB particles aggregate to form fractal clusters. Their\nsize conforms to a power law of the shear rate, $\\xi_c \\propto\n\\dot{\\gamma}^{-m}$, with $m\\simeq 0.5$. Second, drawing insights from the\nfractal structure of clusters, we compute an effective volume fraction\n$\\phi_{\\mathrm{eff}}$ and find that microstructural models adeptly account for\nthe hydrodynamic stress contributions. We identify a critical shear rate\n$\\dot{\\gamma^*}$ and a critical volume fraction $\\phi_{\\mathrm{eff}}^{*}$, at\nwhich the clusters percolate to form a dynamical network."
    },
    {
        "anchor": "Geometry-driven collective ordering of bacterial vortices: Controlling the phases of matter is a challenge that spans from condensed\nmaterials to biological systems. Here, by imposing a geometric boundary\ncondition, we study controlled collective motion of Escherichia coli bacteria.\nA circular microwell isolates a rectified vortex from disordered vortices\nmasked in bulk. For a doublet of microwells, two vortices emerge but their\nspinning directions show transition from parallel to anti-parallel. A\nVicsek-like model for confined self-propelled particles gives the point where\ntwo spinning patterns occur in equal probability and one geometric quantity\ngoverns the transition as seen in experiments. This mechanism shapes rich\npatterns including chiral configurations in a quadruplet of microwells, thus\nrevealing a design principle of active vortices.",
        "positive": "Dynamics of shallow impact cratering: We present data for the time-dependence of wooden spheres penetrating into a\nloose non-cohesive packing of glass beads. The stopping time is a factor of\nthree longer than the time $d/v_\\circ$ needed to travel the total penetration\ndistance $d$ at the impact speed $v_\\circ$. The acceleration decreases\nmonotonically throughout the impact. These kinematics are modelled by a\nposition- and velocity-dependent stopping force that is constrained to\nreproduce prior observations for the scaling of the penetration depth with the\ntotal drop distance."
    },
    {
        "anchor": "Linker-mediated self-assembly of mobile DNA-coated colloids: Developing construction methods of materials tailored for given applications\nwith absolute control over building block placement poses an immense challenge.\nDNA-coated colloids offer the possibility of realising programmable\nself-assembly, which, in principle, can assemble almost any structure in\nequilibrium, but remains challenging experimentally. Here, we propose an\ninnovative system of linker-mediated mobile DNA-coated colloids (mDNACCs), in\nwhich mDNACCs are bridged by the free DNA linkers in solution, whose two\nsingle-stranded DNA tails can bind with specific single-stranded DNA receptors\nof complementary sequence coated on colloids. We formulate a mean-field theory\nefficiently calculating the effective interaction between mDNACCs, where the\nentropy of DNA linkers plays a nontrivial role. Particularly, when the binding\nbetween free DNA linkers in solution and the corresponding receptors on mDNACCs\nis strong, the linker-mediated colloidal interaction is determined by the\nlinker entropy depending on the linker concentration.",
        "positive": "Solitons in polymeric chains with periodic interactions: In this paper we follow the lines of recent works to investigate systems of\ntwo coupled real scalar fields defined by potentials that describe periodic\ninteractions between the scalar fields. We work with polymeric chains\ncontaining periodic interactions between the coupled fields, and we investigate\nthe topological sectors to obtain explicit soliton solutions and their\ncorresponding energy. In particular, we offer an example that considers\ndeoxyribonucleic acid (DNA) as a system of coupled fields, and we present the\nmain steps to describe DNA as a polymeric chain belonging to the class of\nsystems of two coupled real scalar fields."
    },
    {
        "anchor": "Capillarity-Driven Flows at the Continuum Limit: We experimentally investigate the dynamics of capillary-driven flows at the\nnanoscale, using an original platform that combines nanoscale pores and\nmicrofluidic features. Our results show a coherent picture across multiple\nexperiments including imbibition, poroelastic transient flows, and a\ndrying-based method that we introduce. In particular, we exploit extreme drying\nstresses - up to 100 MPa of tension - to drive nanoflows and provide\nquantitative tests of continuum theories of fluid mechanics and thermodynamics\n(e.g. Kelvin-Laplace equation) across an unprecedented range. We isolate the\nbreakdown of continuum as a negative slip length of molecular dimension.",
        "positive": "Rheological and Physicochemical Studies on Emulsions Formulated with\n  Chitosan Previously Dispersed in Aqueous Solutions of Lactic Acid: Chitosan, a natural, cationic polysaccharide, may be a hydrocolloid strategic\nto formulate acidic food products, as it can act as both bio-functional and\ntechnofunctional constituent. Typically, acetic acid is used to disperse\nchitosan in aqueous media, but the use of this acid is limited in food\nformulations due to its flavor. In this study, chitosan was firstly dispersed\n(0.1% m/V) in lactic acid aqueous solutions (pH 3.0, 3.5 or 4.0), and then\nevaluated regarding its thickener and emulsion stabilizer properties. O/W\nemulsions were prepared and characterized in terms of rheological properties,\ndroplets average diameters and droplets $\\zeta$-potential. Emulsions containing\nchitosan were 3 times more viscous than controls without chitosan, and\npresented storage modulus ($G'$) higher than loss modulus ($G''$). Furthermore,\nthey displayed two different populations of droplets (average diameters of 44\nand 365 nm) and positive $\\zeta$-potential values (+50 mV). Droplets average\ndiameters and $\\zeta$-potential did not present significant changes ($p$ >\n0.05) after storage at 25 $^{\\circ}$C during 7 days. This study showed that i)\nfood organic acids other than acetic acid can be used to disperse chitosan for\ntechnological purposes, and ii) chitosan dispersed at very low concentrations\n(0.1% m/V) had relevant effects on rheological and physicochemical aspects of\nfood-grade emulsions."
    },
    {
        "anchor": "Self-Ordering of Buckling, Bending, Bumping Beams: A collection of thin structures buckle, bend, and bump into each-other when\nconfined. This contact can lead to the formation of patterns: hair will\nself-organize in curls; DNA strands will layer into cell nuclei; paper, when\ncrumpled, will fold in on itself, forming a maze of interleaved sheets. This\npattern formation changes how densely the structures can pack, as well as the\nmechanical properties of the system. How and when these patterns form, as well\nas the force required to pack these structures is not currently understood.\nHere we study the emergence of order in a canonical example of packing in\nslender-structures, i.e. a system of parallel growing elastic beams. Using\nexperiments, simulations, and simple theory from statistical mechanics, we\npredict the amount of growth (or, equivalently, the amount of compression) of\nthe beams that will guarantee a global system order, which depends only on the\ninitial geometry of the system. Furthermore, we find that the compressive\nstiffness and stored bending energy of this meta-material is directly\nproportional to the number of beams that are geometrically frustrated at any\ngiven point. We expect these results to elucidate the mechanisms leading to\npattern formation in these kinds of systems, and to provide a new mechanical\nmeta-material, with a tunable resistance to compressive force.",
        "positive": "Structure, phase behavior and inhomogeneous fluid properties of binary\n  dendrimer mixtures: The effective pair potentials between different kinds of dendrimers in\nsolution can be well approximated by appropriate Gaussian functions. We find\nthat in binary dendrimer mixtures the range and strength of the effective\ninteractions depend strongly upon the specific dendrimer architecture. We\nconsider two different types of dendrimer mixtures, employing the Gaussian\neffective pair potentials, to determine the bulk fluid structure and phase\nbehavior. Using a simple mean field density functional theory (DFT) we find\ngood agreement between theory and simulation results for the bulk fluid\nstructure. Depending on the mixture, we find bulk fluid-fluid phase separation\n(macro-phase separation) or micro-phase separation, i.e., a transition to a\nstate characterized by undamped periodic concentration fluctuations. We also\ndetermine the inhomogeneous fluid structure for confinement in spherical\ncavities. Again, we find good agreement between the DFT and simulation results.\nFor the dendrimer mixture exhibiting micro-phase separation, we observe rather\nstriking pattern formation under confinement."
    },
    {
        "anchor": "Local description of the two-dimensional flow of foam through a\n  contraction: The 2D flow of a foam confined in a Hele-Shaw cell through a contraction is\ninvestigated. Its rheological features are quantified using image analysis,\nwith measurements of the elastic stress, rate of plasticity, and velocity. The\nbehavior of the velocity strongly differs at the contraction entrance, where\nthe flow is purely convergent, and at the contraction exit, where a velocity\nundershoot and a re-focussing of the streamlines are unraveled. The yielded\nregion, characterized by a significant rate of plasticity and a maximal stress\namplitude, is concentrated close to the contraction. These qualitative generic\ntrends do not vary significantly with the flow rate, bubble area and\ncontraction geometry, which is characteristic of a robust quasistatic regime.\nUsing surfactants with a high surface viscoelasticity, a marked dependence of\nthe elastic stress on the velocity is exhibited. The results show that the rate\nof plasticity does not only depend on the local magnitude of the deformation\nrate, but also crucially on the orientation of both elastic stresses and\ndeformation rate. It is also discussed how the viscous friction controls the\ndeparture from the quasistatic regime.",
        "positive": "Unified study of viscoelasticity and sound damping in hard and soft\n  amorphous solids: Recent research has made significant progress in understanding the non-phonon\nvibrational states present in amorphous materials. It has been established that\ntheir vibrational density of states follows non-Debye scaling laws. Here, we\nshow that the non-Debye scaling laws play a crucial role in determining\nmaterial properties of a broad range of amorphous solids, from ``hard\"\namorphous solids like structural glasses to ``soft\" amorphous solids such as\nfoams and emulsions. We propose a unified framework of viscoelasticity and\nsound damping for these materials. Although these properties differ\nsignificantly between hard and soft amorphous solids, they are determined by\nthe non-Debye scaling laws. We also validate our framework using numerical\nsimulations."
    },
    {
        "anchor": "Fluctuation-Induced First Order Transition to Collective Motion: The nature of the transition to collective motion in assemblies of aligning\nself-propelled particles remains a long-standing matter of debate. In this\narticle, we focus on dry active matter and show that weak fluctuations suffice\nto generically turn second-order mean-field transitions into a `discontinuous'\ncoexistence scenario. Our theory shows how fluctuations induce a\ndensity-dependence of the polar-field mass, even when this effect is absent at\nmean-field level. In turn, this dependency on density triggers a feedback loop\nbetween ordering and advection that ultimately leads to an inhomogeneous\ntransition to collective motion and the emergence of non-linear travelling\n`flocks'. Importantly, we show that such a fluctuation-induced first order\ntransition is present in both metric models, in which particles align with\nneighbors within a finite distance, and in topological ones, in which alignment\nis not based on relative distances. We compute analytically the noise-induced\nrenormalization of the polar-field mass using stochastic calculus, which we\nfurther back up by a one-loop field-theoretical analysis. Finally, we confirm\nour analytical predictions by numerical simulations of fluctuating\nhydrodynamics as well as of topological microscopic models with either\n$k$-nearest neighbors or Voronoi alignment.",
        "positive": "Novel morphologies for laterally decorated metaparticles: Molecular\n  dynamics simulation: We consider a mesoscale model for nano-sized metaparticles (MPs) composed of\na central sphere decorated by polymer chains with laterally attached\nspherocylinder. The latter mimics the mesogenic (e.g., cyanobiphenyl) group.\nMolecular dynamics simulations of $100$ MPs reveal the existence of two novel\nmorphologies: $\\textrm{uCol}_\\mathrm{h}$ (hexagonal columnar arrangement of MPs\nwith strong uniaxial order of mesogens collinear to the columns axis) and\n$\\mathrm{wCol}_\\mathrm{h}$ [the same arrangement of MPs but with weak or no\nliquid crystalline (LC) order]. Collinearity of the LC director and the\ncolumnar axis in $\\textrm{uCol}_\\mathrm{h}$ morphology indicates its\npotentially different opto-mechanical response to an external perturbation as\ncompared to the columnar phase for the terminally attached mesogens.\nPreliminary analysis of the structures of both phases is performed by studying\nthe order parameters and by visualisation of the MPs arrangements. Different\nmechanisms for the mesogens reorientation are pointed out for the cases of\ntheir terminal and lateral attachment."
    },
    {
        "anchor": "What keeps nanopores boiling: The liquid to vapour transition can occur at unexpected conditions in\nnanopores, opening the door to fundamental questions and new technologies. The\nphysics of boiling in confinement is progressively introduced, starting from\nclassical nucleation theory, passing through nanoscale effects, and terminating\nto the material and external parameters which affect the boiling conditions.\nThe relevance of boiling in specific nanoconfined systems is discussed,\nfocusing on heterogeneous lyophobic systems, chromatographic columns, and ion\nchannels. The current level of control of boiling in nanopores enabled by\nmicroporous materials, as metal organic frameworks, and biological nanopores\npaves the way to thrilling theoretical challenges and to new technological\nopportunities in the fields of energy, neuromorphic computing, and sensing.",
        "positive": "On the deformation of spontaneously twisted fluctuating ribbons: A theoretical analysis of the effect of force and torque on spontaneously\ntwisted, fluctuating elastic ribbons is presented. We find that when a filament\nwith a straight center line and a spontaneously twisted noncircular cross\nsection is subjected to a sufficiently strong extensional force, its average\nelongation exhibits an asymmetric response to large over and undertwist. We\nconstruct the stability diagram that describes the buckling transition of such\nribbons under the opposing action of force and torque and show that all the\npredicted behaviors can be understood in terms of continuous transformations\nbetween straight and spiral/helical states of the ribbon. The relation between\nour results and experimental observations on DNA is discussed and a new\nreentrant spiral to rod transition is predicted at intermediate values of twist\nrigidity and applied force."
    },
    {
        "anchor": "Non-local effects in the shear banding of a thixotropic yield stress\n  fluid: We observe a novel type of shear banding in the rheology of thixotropic\nyield-stress fluids that is due to the coupling of both non-locality and\nthixotropy. The latter is known to lead to shear banding even in homogeneous\nstress fields, but the bands observed in the presence of non-local effects\nappear different as the shear rate varies continuously over the shear band.\nHere, we introduce a simple non-local model for the shear banding (NL-SB), and\nwe implement it for the analysis of micron-scale rheo-MRI velocimetry\nmeasurements of a milk microgel suspension in a cone-and-plate geometry. The\nproposed NL-SB model accurately quantifies the cooperativity length and yields\nvalues in the order of the aggregate size in the microgel.",
        "positive": "Error Correction and Digitalization Concepts in Biochemical Computing: We offer a theoretical design of new systems that show promise for digital\nbiochemical computing, including realizations of error correction by utilizing\nredundancy, as well as signal rectification. The approach includes information\nprocessing using encoded DNA sequences, DNAzyme biocatalyzed reactions and the\nuse of DNA-functionalized magnetic nanoparticles. Digital XOR and NAND logic\ngates and copying (fanout) are designed using the same components."
    },
    {
        "anchor": "Molecular structural order and anomalies in liquid silica: The present investigation examines the relationship between structural order,\ndiffusivity anomalies, and density anomalies in liquid silica by means of\nmolecular dynamics simulations. We use previously defined orientational and\ntranslational order parameters to quantify local structural order in atomic\nconfigurations. Extensive simulations are performed at different state points\nto measure structural order, diffusivity, and thermodynamic properties. It is\nfound that silica shares many trends recently reported for water [J. R.\nErrington and P. G. Debenedetti, Nature 409, 318 (2001)]. At intermediate\ndensities, the distribution of local orientational order is bimodal. At fixed\ntemperature, order parameter extrema occur upon compression: a maximum in\norientational order followed by a minimum in translational order. Unlike water,\nhowever, silica's translational order parameter minimum is broad, and there is\nno range of thermodynamic conditions where both parameters are strictly\ncoupled. Furthermore, the temperature-density regime where both structural\norder parameters decrease upon isothermal compression (the structurally\nanomalous regime) does not encompass the region of diffusivity anomalies, as\nwas the case for water.",
        "positive": "Biaxial nematics: symmetries, order domains and field-induced phase\n  transitions: We study the symmetry and the spatial uniformity of orientational order of\nthe biaxial nematic phase in the light of recent experimental observations of\nphase biaxiality in thermotropic bent-core and calamitic-tetramer nematics. We\npresent evidence supporting monoclinic symmetry, instead of the usually assumed\northorhombic. We describe the use of deuterium NMR to differentiate between the\npossible symmetries. We present the spatial aspects of biaxial order in the\ncontext of the cluster model, wherein macroscopic biaxiality can result from\nthe field-induced alignment of biaxial and possibly polar domains. We discuss\nthe implications of different symmetries, in conjunction with the microdomain\nstructure of the biaxial phase, on the alignment of biaxial nematics and on the\nmeasurements of biaxial order."
    },
    {
        "anchor": "Microgels Adsorbed at Liquid-Liquid Interfaces: A Joint Numerical and\n  Experimental Study: Soft particles display highly versatile properties with respect to hard\ncolloids, even more so at fluid-fluid interfaces. In particular, microgels,\nconsisting of a cross-linked polymer network, are able to deform and flatten\nupon adsorption at the interface due to the balance between surface tension and\ninternal elasticity. Despite the existence of experimental results, a detailed\ntheoretical understanding of this phenomenon is still lacking due to the\nabsence of appropriate microscopic models. In this work, we propose an advanced\nmodelling of microgels at a flat water/oil interface. The model builds on a\nrealistic description of the internal polymeric architecture and\nsingle-particle properties of the microgel and is able to reproduce its\nexperimentally observed shape at the interface. Complementing molecular\ndynamics simulations with in-situ cryo-electron microscopy experiments and\natomic force microscopy imaging after Langmuir-Blodgett deposition, we compare\nthe morphology of the microgels for different values of the cross-linking\nratios. Our model allows for a systematic microscopic investigation of soft\nparticles at fluid interfaces, which is essential to develop predictive power\nfor the use of microgels in a broad range of applications, including the\nstabilization of smart emulsions and the versatile patterning of surfaces.",
        "positive": "Dynamics of collapsing and exploding Bose-Einstein condensed vortex\n  state: Using the time-dependent mean-field Gross-Pitaevskii equation we study the\ndynamics of small repulsive Bose-Einstein condensed vortex states of ^{85}Rb\natoms in a cylindrical trap with low angular momentum hbar L per atom (L <= 6),\nwhen the atomic interaction is suddenly turned attractive by manipulating the\nexternal magnetic field near a Feshbach resonance. Consequently, the condensate\ncollapses and ejects atoms via explosion and a remnant condensate with a\nsmaller number of atoms emerges that survives for a long time. Detail of this\ncollapse and explosion is compared critically with a similar experiment\nperformed with zero angular momentum (L=0). Suggestion for future experiment\nwith vortex state is made."
    },
    {
        "anchor": "Nanofluidic Rocking Brownian Motors: Control and transport of nanoscale objects in fluids is challenging because\nof the unfavorable scaling of most interaction mechanisms to small length\nscales. We design energy landscapes for nanoparticles by accurately shaping the\ngeometry of a nanofluidic slit and exploiting the electrostatic interaction\nbetween like charged particles and walls. Directed transport is performed by\ncombining asymmetric potentials with an oscillating electric field to achieve a\nrocking Brownian motor. Using 60\\,nm diameter gold spheres, we investigate the\nphysics of the motors with high spatio-temporal resolution, enabling a\nparameter-free comparison with theory. We fabricated a sorting device that\nseparates 60- and 100-nanometer particles in opposing directions within\nseconds. Modeling suggests that the device separates particles with a radial\ndifference of 1 nanometer.",
        "positive": "Design of Chemotaxis Devices Using Nano-Motors: Several designs for micro-devices for chemotaxis based on nano-motors are\nproposed. The nano- or micro-motors are the conventional Janus rods or spheres\nthat are powered by the catalytic reaction of fuels such as hydrogen peroxide.\nIt is shown how these can be linked to make a device that can follow a\nconcentration gradient of the fuel. The feasibility of assembling the devices\nusing micromanipulation or metallic deposition is discussed. A possible design\nprinciple is suggested for a device that follows the concentration gradient of\nan analyte other than the fuel."
    },
    {
        "anchor": "Unified approach to reset processes and application to coupling between\n  process and reset: We present a unified approach to those observables of stochastic processes\nunder reset that take the form of averages of functionals depending on the most\nrecent renewal period. We derive solutions for the observables, and determine\nthe conditions for existence and equality of their stationary values with and\nwithout reset. For intermittent reset times, we derive exact asymptotic\nexpressions for observables that vary asymptotically as a power of time. We\nillustrate the general approach with general and particular results for the\npower spectral density, and moments of subdiffusive processes. We focus on\ncoupling of the process and reset via a diffusion-decay process with\nmicroscopic dependence between transport and decay. In contrast to the\nuncoupled case, we find that restarting the particle upon decay does not\nproduce a probability current equal to the decay rate, but instead drastically\nalters the time dependence of the decay rate and the resulting current.",
        "positive": "General criterion for controllable conformational transitions of single\n  and double stranded DNA: Chain-like macromolecules in solution, whether biological or synthetic,\ntransform from a spatially extended conformation to a compact one upon change\nof temperature or solvent qualities. This sharp transition plays a key role in\nvarious phenomena, including DNA condensation, protein folding, and the\nbehaviour of polymer solutions. In biological processes such as DNA\ncondensation the collapse is sensitively induced by a small amount of added\nmolecules. Here we derive a general criterion for the effect of such agents on\nconformational transitions. We find two different scenarios depending on chain\nstiffness. If the persistence length --the characteristic distance along which\nthe chain retains its direction-- is smaller than the range of attractive\ncorrelations induced by the agent (typically up to several nanometres), the\nchain contracts gradually. Stiffer chains undergo sharp collapse. We thereby\nsuggest that the enhanced rigidity of double-stranded DNA as compared to the\nsingle strand is a prerequisite for sharp, controllable conformational\ntransitions."
    },
    {
        "anchor": "Confined active matter in external fields: We analyze a dilute suspension of active particles confined between walls and\nsubjected to fields that can modulate particle speed as well as orientation.\nGenerally, the particle distribution is different in the bulk compared to near\nthe walls. In the bulk, particles tend to accumulate in the regions of low\nspeed, but in the presence of an orienting field, particles rotate to align\nwith the field and accumulate downstream in the field direction. At the walls,\nparticles tend to accumulate pointing into the walls and thereby exert pressure\non walls. But the presence of strong orienting fields can cause the particles\nto reorient away from the walls, and hence shows a possible mechanism for\npreventing contamination of surfaces. The pressure at the walls depends on the\nwall separation and the field strengths. This work demonstrates how multiple\nfields with different functionalities can be used to control active matter\nunder confinement.",
        "positive": "Programming shape using kirigami tessellations: Kirigami tessellations, regular planar patterns formed by cutting flat, thin\nsheets, have attracted recent scientific interest for their rich geometries,\nsurprising material properties and promise for technologies. Here we pose and\nsolve the inverse problem of designing the number, size, and orientation of\ncuts that allows us to convert a closed, compact regular kirigami tessellation\nof the plane into a deployment that conforms approximately to any prescribed\ntarget shape in two and three dimensions. We do this by first identifying the\nconstraints on the lengths and angles of generalized kirigami tessellations\nwhich guarantee that their reconfigured face geometries can be contracted from\na non-trivial deployed shape to a novel planar cut pattern. We encode these\nconditions in a flexible constrained optimization framework which allows us to\ndeform the geometry of periodic kirigami tesselations with three, four, and\nsixfold symmetry, among others, into generalized kirigami patterns that deploy\nto a wide variety of prescribed boundary target shapes. Physically fabricated\nmodels verify our inverse design approach and allow us to determine the tunable\nmaterial response of the resulting structures. We then extend our framework to\ncreate generalized kirigami patterns that deploy to approximate curved surfaces\nin $\\mathbb{R}^3$. Altogether, this work illustrates a novel framework for\ndesigning complex, shape-changing sheets from simple cuts showing the power of\nkirigami tessellations as flexible mechanical metamaterials."
    },
    {
        "anchor": "Significance of Elastic Coupling for Stresses and Leakage in Frictional\n  Contacts: We study how the commonly neglected coupling of normal and in-plane elastic\nresponse affects tribological properties when Hertzian or randomly rough\nindenters slide past an elastic body. Compressibility-induced coupling is found\nto substantially increase maximum tensile stresses, which cause materials to\nfail, and to decrease friction such that Amontons law is violated\nmacroscopically even when it holds microscopically. Confinement-induced\ncoupling increases friction and enlarges domains of high tension. Moreover,\nboth types of coupling affect the gap topography and thereby leakage. Thus,\ncoupling can be much more than a minor perturbation of a mechanical contact.",
        "positive": "Different anomalous diffusion regimes measured in the dynamics of tracer\n  particles in actin networks: It was previously believed that diffusion of a tracer particle in a\nviscoelastic material should be of the fractional Brownian motion (fBm) type.\nThis is due to the long-term memory in the response of such materials to\nmechanical perturbations. Surprisingly, the diffusion of a tracer particle in a\nnetwork of a purified protein, actin, was found to conform to the continuous\ntime random walk (CTRW) type in one study that focused on the ensemble average\ncharacteristics. Here, we analyze the dynamics of two differently sized tracer\nparticles in actin networks of different mesh sizes. We find that the ratio of\ntracer particle size to the characteristic length scale of a bio-polymer\nnetwork plays a crucial role in determining the type of diffusion the particle\nperforms. We find that the tracer particle diffusion has features of fBm when\nthe particle is large compared to the mesh size, of normal diffusion when the\nparticle is much smaller than the mesh size, and of CTRW in between these two\nlimits. Based on our findings, we propose and verify numerically a new model\nfor the tracer particle's motion in all regimes. Our model suggests that\ndiffusion in actin networks consists of fBm of the tracer particle coupled with\noccasional caging events with power-law-distributed escape times."
    },
    {
        "anchor": "Bloch oscillations of cold atoms in optical lattices: This work is devoted to Bloch oscillations (BO) of cold neutral atoms in\noptical lattices. After a general introduction to the phenomenon of BO and its\nrealization in optical lattices, we study different extentions of this problem,\nwhich account for recent developments in this field. These are two-dimensional\nBO, decoherence of BO, and BO in correlated systems. Although these problems\nare discussed in relation to the system of cold atoms in optical lattices, many\nof the results are of general validity and can be well applied to other systems\nshowing the phenomenon of BO.",
        "positive": "Renormalized One-loop Theory of Correlations in Disordered Diblock\n  Copolymers: A renormalized one-loop theory (ROL) is used to calculate corrections to the\nrandom phase approximation (RPA) for the structure factor $\\Sc(q)$ in\ndisordered diblock copolymer melts. Predictions are given for the peak\nintensity $S(q^{\\star})$, peak position $q^{\\star}$, and single-chain\nstatistics for symmetric and asymmetric copolymers as functions of $\\chi N$,\nwhere $\\chi$ is the Flory-Huggins interaction parameter and $N$ is the degree\nof polymerization. The ROL and Fredrickson-Helfand (FH) theories are found to\nyield asymptotically equivalent results for the dependence of the peak\nintensity $S(q^{\\star})$ upon $\\chi N$ for symmetric diblock copolymers in the\nlimit of strong scattering, or large $\\chi N$, but yield qualitatively\ndifferent predictions for symmetric copolymers far from the ODT and for\nasymmetric copolymers. The ROL theory predicts a suppression of $S(q^\\star)$\nand a decrease of $q^{\\star}$ for large values of $\\chi N$, relative to the RPA\npredictions, but an enhancement of $S(q^{\\star})$ and an increase in\n$q^{\\star}$ for small $\\chi N$ ($\\chi N < 5$). By separating intra- and\ninter-molecular contributions to $S^{-1}(q)$, we show that the decrease in\n$q^{\\star}$ near the ODT is caused by the $q$ dependence of the intermolecular\ndirect correlation function, and is unrelated to any change in single-chain\nstatistics, but that the increase in $q^{\\star}$ at small values of $\\chi N$ is\na result of non-Gaussian single-chain statistics."
    },
    {
        "anchor": "Numerical simulations of complex fluid-fluid interface dynamics: Interfaces between two fluids are ubiquitous and of special importance for\nindustrial applications, e.g., stabilisation of emulsions. The dynamics of\nfluid-fluid interfaces is difficult to study because these interfaces are\nusually deformable and their shapes are not known a priori. Since experiments\ndo not provide access to all observables of interest, computer simulations pose\nattractive alternatives to gain insight into the physics of interfaces. In the\npresent article, we restrict ourselves to systems with dimensions comparable to\nthe lateral interface extensions. We provide a critical discussion of three\nnumerical schemes coupled to the lattice Boltzmann method as a solver for the\nhydrodynamics of the problem: (a) the immersed boundary method for the\nsimulation of vesicles and capsules, the Shan-Chen pseudopotential approach for\nmulti-component fluids in combination with (b) an additional\nadvection-diffusion component for surfactant modelling and (c) a molecular\ndynamics algorithm for the simulation of nanoparticles acting as emulsifiers.",
        "positive": "Stress-stress Correlations Reveal Force Chains in Gels: We investigate the spatial correlations of microscopic stresses in soft\nparticulate gels, using 2D and 3D numerical simulations. We use a recently\ndeveloped theoretical framework predicting the analytical form of stress-stress\ncorrelations in amorphous assemblies of athermal grains that acquire rigidity\nunder an external load. These correlations exhibit a pinch-point singularity in\nFourier space leading to long-range correlations and strong anisotropy in real\nspace, which are at the origin of force-chains in granular solids. Our analysis\nfor the model particulate gels at low particle volume fractions demonstrates\nthat stress-stress correlations in these soft materials have characteristics\nvery similar to those in granular solids and can be used to identify force\nchains. We show that the stress-stress correlations can distinguish floppy from\nrigid gel networks and the intensity patterns reflect changes in shear moduli\nand network topology, due to the emergence of rigid structures during\nsolidification."
    },
    {
        "anchor": "Stretch-independent magnetization in incompressible magnetorheological\n  elastomers: In this study, we perform a critical examination of the phenomenon where the\nmagnetization is stretch-independent in incompressible hard-magnetic\nmagnetorheological elastomers (h-MREs), as observed in several recent\nexperimental and numerical investigations. We demonstrate that the fully\ndissipative model proposed by Mukherjee et al. (2021) may be reduced, under\nphysically consistent assumptions, to that of Yan et al. (2023), but not that\nof Zhao et al. (2019). In cases where the h-MRE solid undergoes non-negligible\nstretching, the model of Zhao et al. (2019) provides predictions that are in\ndisagreement with experimental observations, given that, by construction, that\nmodel produces a magnetization response that is not stretch-independent. By\ncontrast, the other two models are able to describe this important feature\npresent in h-MREs, as well as in incompressible magnetically soft s-MRES. Note\nthat in cases where stretching is negligible, such as for inextensible slender\nstructures under bending deformation, the Zhao et al. (2019) model provides\naccurate predictions despite its underlying assumptions. Additionally, our\nanalysis reveals two key points about the magnetization vector in the context\nof the more general, fully dissipative model. First, the magnetization can be\nrelated to an internal variable in that theory. However, it cannot be formally\nused as an internal variable except in the special case of an ideal magnet,\nand, as such, it is subject to constitutive assumptions. Furthermore, we\nclarify that the magnetization vector alone is insufficient to describe\nentirely the magnetic response of an MRE solid; instead, the introduction of\none of the original Maxwell fields is always necessary for a complete\nrepresentation.",
        "positive": "Homogeneous crystallization in cyclically sheared frictionless grains: Many experiments over the past half century have shown that, for a range of\nprotocols, granular materials compact under pressure and repeated small\ndisturbances. A recent experiment on cyclically sheared spherical grains showed\nsignificant compaction via homogeneous crystallization (Rietz et al., 2018).\nHere we present numerical simulations of frictionless, purely repulsive spheres\nundergoing cyclic simple shear with dissipative Newtonian dynamics at fixed\nvertical load. We show that for sufficiently small strain amplitudes, cyclic\nshear gives rise to homogeneous crystallization at a volume fraction $\\phi =\n0.646 \\pm 0.001$. This result indicates that neither friction nor gravity is\nessential for homogeneous crystallization in driven granular media."
    },
    {
        "anchor": "Stress relaxation in a perfect nanocrystal by coherent ejection of\n  lattice layers: We show that a small crystal trapped within a potential well and in contact\nwith its own fluid, responds to large compressive stresses by a novel mechanism\n-- the transfer of complete lattice layers across the solid-fluid interface.\nFurther, when the solid is impacted by a momentum impulse set up in the fluid,\na coherently ejected lattice layer carries away a definite quantity of energy\nand momentum, resulting in a sharp peak in the calculated phonon absorption\nspectrum. Apart from its relevance to studies of stability and failure of small\nsized solids, such coherent nanospallation may be used to make atomic wires or\nmonolayer films.",
        "positive": "Dynamic Fluctuations of Semiflexible Polymers: We develop a scaling theory to describe dynamic fluctuations of a\nsemiflexible polymer and find several distinct regimes. We performed\nsimulations to characterize the longitudinal and transverse dynamics; using\nensemble averaging for a range of different degrees of coarse-graining we avoid\nthe problems of slow equilibration often encountered in simulations. We find\nthat the longitudinal fluctuations of a semiflexible object scales as t^7/8.\nThese fluctuations are correlated over a length which varies as t^1/8. Our\nresults are pertinent to the interpretation of high frequency microrheology\nexperiments in actin solutions."
    },
    {
        "anchor": "Numerical study of the glass-glass transition in short-ranged attractive\n  colloids: We report extensive numerical simulations in the {\\it glass} region for a\nsimple model of short-ranged attractive colloids, the square well model. We\ninvestigate the behavior of the density autocorrelation function and of the\nstatic structure factor in the region of temperatures and packing fractions\nwhere a glass-glass transition is expected according to theoretical\npredictions. We strengthen our observations by studying both waiting time and\nhistory dependence of the numerical results. We provide evidence supporting the\npossibility that activated bond-breaking processes destabilize the attractive\nglass, preventing the full observation of a sharp glass-glass kinetic\ntransition.",
        "positive": "Mean first passage time of active Brownian particle in one dimension: We investigate the mean first passage time of an active Brownian particle in\none dimension using numerical simulations. The activity in one dimension is\nmodeled as a two state model; the particle moves with a constant propulsion\nstrength but its orientation switches from one state to other as in a random\ntelegraphic process. We study the influence of a finite resetting rate $r$ on\nthe mean first passage time to a fixed target of a single free Active Brownian\nParticle and map this result using an effective diffusion process. As in the\ncase of a passive Brownian particle, we can find an optimal resetting rate\n$r^*$ for an active Brownian particle for which the target is found with the\nminimum average time. In the case of the presence of an external potential, we\nfind good agreement between the theory and numerical simulations using an\neffective potential approach."
    },
    {
        "anchor": "Higher Corrections to the Mass Current in the Weakly Inhomogeneous\n  A-phase of Helium-3: Two new general representations (the series and the integral) for the mass\ncurrent $\\vj$ in weakly inhomogeneous superfluid A-phase of Helium--3 are\nobtained near zero of temperature by solving the Dyson-Gorkov equation. These\nrepresentations result in additional correcting contribution to the standard\nleading expression for $\\vj$ which is of first order in gradients of the\norbital angular momentum vector $\\hl$. The total supplementary term is found as\nintegral, and, provided the London limit holds, the procedure is advanced to\nexpand it at T=0 asymptotically by the Laplace method in powers of gradients of\n$\\hl$. Three special static orientations of $\\hl$ with respect to its curl are\nconsidered to calculate the higher correcting terms up to third order.\nCoefficients at the quadratic terms are estimated numerically, new cubic\ncontributions are found which contain the logarithm of the London parameter.",
        "positive": "Chiral and achiral mechanisms of self-limiting, twisted bundle assembly: A generalized theory of the self-limiting assembly of twisted bundles of\nfilaments and columns is presented. Bundles and fibers form in a broad variety\nof supramolecular systems, from biological to synthetic materials. A\nwidely-invoked mechanism to explain their finite diameter relies on chirality\ntransfer from the molecular constituents to collective twist of the assembly,\nthe effect of which frustrates the lateral assembly and can select equilibrium,\nfinite diameters of bundles. In this article, the thermodynamics of\ntwisted-bundle assembly is analyzed to understand if chirality transfer is\nnecessary for self-limitation, or instead, if spontaneously-twisting, achiral\nbundles also exhibit self-limited assembly. A generalized description is\ninvoked for the elastic costs imposed by twist for bundles of various states of\nintra-bundle order from nematic to crystalline, as well as a generic mechanism\nfor generating twist, classified both by {\\it chirality} but also the {\\it\ntwist susceptibility} of inter-filament alignment. The theory provides a\ncomprehensive set of predictions for the equilibrium twist and size of bundles\nas a function of surface energy as well as chirality, twist susceptibility, and\nelasticity of bundles. Moreover, it shows that while spontaneous twist can lead\nto self-limitation, assembly of twisted {\\it achiral} bundles can be\ndistinguished qualitatively in terms of their range of equilibrium sizes and\nthermodynamic stability relative to bulk (untwisted) states."
    },
    {
        "anchor": "Liquid-vapor interface of a polydisperse fluid: We report a Grand Canonical Monte Carlo simulation study of the liquid-vapor\ninterface of a model fluid exhibiting polydispersity in terms of the particle\nsize $\\sigma$. The bulk density distribution, $\\rho^0(\\sigma)$, of the system\nis controlled by the imposed chemical potential distribution $\\mu(\\sigma)$. We\nchoose the latter such that $\\rho^0(\\sigma)$ assumes a Schulz form with\nassociated degree of polydispersity $\\approx 14%$. By introducing a smooth\nattractive wall, a planar liquid-vapor interface is formed for bulk state\npoints within the region of liquid-vapor coexistence. Owing to fractionation,\nthe pure liquid phase is enriched in large particles, with respect to the\ncoexisting vapor. We investigate how the spatial non-uniformity of the density\nnear the liquid-vapor interface affects the evolution of the local distribution\nof particle sizes between the limiting pure phase forms. We find (as previously\npredicted by density functional theory, Bellier-Castella {\\em et al}, Phys.\nRev. {\\bf E65}, 021503 (2002)) a segregation of smaller particles to the\ninterface. The magnitude of this effect is quantified for various $\\sigma$ via\nmeasurements of the relative adsorption. Additionally, we consider the utility\nof various estimators for the interfacial width and highlight the difficulties\nof isolating the intrinsic contribution of polydispersity to this width.",
        "positive": "Numerical study of a slip-link model for polymer melts and\n  nanocomposites: We present a numerical study of the slip link model introduced by Likhtman\nfor describing the dy- namics of dense polymer melts. After reviewing the\ntechnical aspects associated with the implemen- tation of the model, we extend\nprevious work in several directions. The dependence of the relaxation modulus\nwith the slip link density and the slip link stiffness is reported. Then the\nnonlinear rheolog- ical properties of the model, for a particular set of\nparameters, are explored. Finally, we introduce excluded volume interactions in\na mean field such as manner in order to describe inhomogeneous systems, and we\napply this description to a simple nanocomposite model. With this extension,\nthe slip link model appears as a simple and generic model of a polymer melt,\nthat can be used as an alternative to molecular dynamics for coarse grained\nsimulations of complex polymeric systems."
    },
    {
        "anchor": "Topological elasticity of flexible structures: Flexible mechanical metamaterials possess repeating structural motifs that\nimbue them with novel, exciting properties including programmability, anomalous\nelastic moduli and nonlinear and robust response. We address such structures\nvia micromorphic continuum elasticity, which allows highly nonuniform\ndeformations (missed in conventional elasticity) within unit cells that\nnevertheless vary smoothly between cells. We show that the bulk microstructure\ngives rise to boundary elastic terms. Discrete lattice theories have shown that\ncritically coordinated structures possess a topological invariant which\ndetermines the placement of low-energy modes on edges of such a system. We show\nthat in continuum systems a new topological invariant emerges which relates the\ndifference in the number of such modes between two opposing edges. Guided by\nthe continuum limit of the lattice structures, we identify macroscopic\nexperimental observables for these topological properties that may be observed\nindependently on a new length scale above that of the microstructure.",
        "positive": "Stable covalently photo-cross-linked poly(ionic liquid) membrane with\n  gradient pore size: An imidazolium-based poly(ionic liquid) is covalently cross-linked via UV\nlight-induced thiolene (click) chemistry to yield a stable porous\npolyelectrolyte membrane with gradients of crosslink density and pore size\ndistribution along its cross-section."
    },
    {
        "anchor": "Graph-informed simulation-based inference for models of active matter: Many collective systems exist in nature far from equilibrium, ranging from\ncellular sheets up to flocks of birds. These systems reflect a form of active\nmatter, whereby individual material components have internal energy. Under\nspecific parameter regimes, these active systems undergo phase transitions\nwhereby small fluctuations of single components can lead to global changes to\nthe rheology of the system. Simulations and methods from statistical physics\nare typically used to understand and predict these phase transitions for\nreal-world observations. In this work, we demonstrate that simulation-based\ninference can be used to robustly infer active matter parameters from system\nobservations. Moreover, we demonstrate that a small number (from one to three)\nsnapshots of the system can be used for parameter inference and that this\ngraph-informed approach outperforms typical metrics such as the average\nvelocity or mean square displacement of the system. Our work highlights that\nhigh-level system information is contained within the relational structure of a\ncollective system and that this can be exploited to better couple models to\ndata.",
        "positive": "A coarse-grained polymer model for studying the glass transition: To study the cooling behavior and the glass transition of polymer melts in\nbulk and with free surfaces a coarse-grained weakly semi-flexible polymer model\nis developed. Based on a standard bead spring model with purely repulsive\ninteractions an attractive potential between non-bonded monomers is added, such\nthat the pressure of polymer melts is tuned to zero. Additionally, the commonly\nused bond bending potential [Everaers et al., Science 303, 823 (2004)]\ncontrolling the chain stiffness is replaced by a new bond bending potential.\nFor this model, we show that the Kuhn length and the internal distances along\nthe chains in the melt only very weakly depend on temperature, just as for\ntypical experimental systems. The glass transition is observed by the\ntemperature dependency of the melt density and the characteristic non-Arrhenius\nslowing down of the chain mobility. The model is set to allow for a fast switch\nbetween models, for which a wealth of data already exists."
    },
    {
        "anchor": "Theoretical calculations of phase diagrams and self-assembly in patchy\n  colloids: Review paper. Chapter 6 in Janus Particles Synthesis, Self-Assembly, and\nApplications pages 108-137, Edited by Steve Granick and Shan Jiang (RCS\nPublishing 2012) http://www.rsc.org/Shop/books/2012/9781849734233.asp",
        "positive": "Scaling description of frictionless dense suspensions under\n  inhomogeneous flow: Predicting the rheology of dense suspensions under inhomogeneous flow is\ncrucial in many industrial and geophysical applications, yet the conventional\n`$\\mu(J)$' framework is limited to homogeneous conditions in which the shear\nrate and solids fraction are spatially invariant. To address this shortcoming,\nwe use particle-based simulations of frictionless dense suspensions to derive\nnew constitutive laws that unify the rheological response under both\nhomogeneous and inhomogeneous conditions. By defining a new dimensionless\nnumber associated with particle velocity fluctuations and combining it with the\nviscous number, the macroscopic friction and the solids fraction, we obtain\nscaling relations that collapse data from homogeneous and inhomogeneous\nsimulations. The relations allow prediction of the steady state velocity,\nstress and volume fraction fields using only knowledge of the applied driving\nforce."
    },
    {
        "anchor": "Polymer Translocation Induced by a Bad Solvent: We employ 3D Langevin Dynamics simulations to study the dynamics of polymer\nchains translocating through a nanopore in presence of asymmetric solvent\nconditions. Initially a large fraction ($>$ 50%) of the chain is placed at the\n\\textit{cis} side in a good solvent while the $trans$ segments are placed in a\nbad solvent that causes the chain to collapse and promotes translocation from\nthe $cis$ to the $trans$ side. In particular, we study the ratcheting effect of\na globule formed at the \\textit{trans} side created by the translocated\nsegment, and how this ratchet drives the system towards faster translocation.\nUnlike in the case of unbiased or externally forced translocation where the\nmean first passage time $\\langle \\tau \\rangle $ is often characterized by\nalgebraic scaling as a function of the chain length $N$ with a single scaling\nexponent $\\alpha$, and the histogram of the mean first passage time\n$P(\\tau/\\langle\\tau \\rangle)$ exhibits scaling, we find that scaling is not\nwell obeyed. For relatively long chains we find $\\langle \\tau \\rangle \\sim\nN^\\alpha$ where $\\alpha \\approx 1$ for $\\varepsilon/k_{B}T > 1$. In this limit,\nwe also find that translocation proceeds with a nearly constant velocity of the\nindividual beads(monomers), which is attributed to the coiling of the globule.\nWe provide an approximate theory assuming rotat ional motion restricted on a 2D\ndisc to demonstrate that there is a crossover from diffusive behavior of the\ncenter of mass for short chains to a single file translocation for long chains,\nwhere the average translocation time scales linearly with the chain length $N$.",
        "positive": "Nonlinear Rheology in a Model Biological Tissue: Mechanical signaling plays a key role in biological processes like embryo\ndevelopment and cancer growth. One prominent way to probe mechanical properties\nof tissues is to study their response to externally applied forces. Using a\nparticle-based model featuring random apoptosis and environment-dependent\ndivision rates, we evidence a crossover from linear flow to a shear-thinning\nregime with increasing shear rate. To rationalize this non-linear flow we\nderive a theoretical mean-field scenario that accounts for the interplay of\nmechanical and active noise in local stresses. These noises are respectively\ngenerated by the elastic response of the cell matrix to cell rearrangements and\nby the internal activity."
    },
    {
        "anchor": "Casimir stresses in active nematic films: We calculate the Casimir stresses in a thin layer of active fluid with\nnematic order. By using a stochastic hydrodynamic approach for an active fluid\nlayer of finite thickness $L$, we generalize the Casimir stress for nematic\nliquid crystals in thermal equilibrium to active systems. We show that the\nactive Casimir stress differs significantly from its equilibrium counterpart.\nFor contractile activity, the active Casimir stress, although attractive like\nits equilibrium counterpart, diverges logarithmically as $L$ approaches a\nthreshold of the spontaneous flow instability from below. In contrast, for\nsmall extensile activity, it is repulsive, has no divergence at any $L$ and has\na scaling with $L$ different from its equilibrium counterpart.",
        "positive": "Interplay of internal stresses, electric stresses and surface diffusion\n  in polymer films: We investigate two destabilization mechanisms for elastic polymer films and\nput them into a general framework: first, instabilities due to in-plane stress\nand second due to an externally applied electric field normal to the film's\nfree surface. As shown recently, polymer films are often stressed due to\nout-of-equilibrium fabrication processes as e.g. spin coating. Via an\nAsaro-Tiller-Grinfeld mechanism as known from solids, the system can decrease\nits energy by undulating its surface by surface diffusion of polymers and\nthereby relaxing stresses. On the other hand, application of an electric field\nis widely used experimentally to structure thin films: when the electric\nMaxwell surface stress overcomes surface tension and elastic restoring forces,\nthe system undulates with a wavelength determined by the film thickness. We\ndevelop a theory taking into account both mechanisms simultaneously and discuss\ntheir interplay and the effects of the boundary conditions both at the\nsubstrate and the free surface."
    },
    {
        "anchor": "From n-layer planar ordering to the monolayer homeotropic structure of\n  confined hard rods: The effect of shape anisotropy and wall-to-wall\n  separation: Using the Parsons Lee theory we examined the effect of shape anisotropy and\nthe wall to wall separation on the phase behavior of the hard parallelepiped\nrods with dimensions L, D, and D (L>D) in such narrow slitlike pores which only\none homeotropic layer can form. The phase structures, including biaxiality,\nplanar nematic layering transition as well as planar to homeotropic, were\nstudied for some separations in the range 2.5D<H<10.0D for H-D<L<H.",
        "positive": "A simple diatomic potential that prevents crystallization in supercooled\n  liquids simulations: We study a simple and versatile diatomic potential function coined to prevent\ncrystallization in supercooled liquids. We show that the corresponding liquid\ndoes not crystallize even with very long simulation runs at the lowest\ntemperature that we can access with ergodic simulations. The medium displays\nthe usual features of supercooled materials and a non-Arrhenius dependence of\nthe diffusion coefficient and alpha relaxation time with temperature. We also\nobserve the breakdown of the Stokes-Einstein relation at low temperatures."
    },
    {
        "anchor": "Chemical reaction motifs driving non-equilibrium behaviors in phase\n  separating materials: Chemical reactions that couple to systems that phase separate have been\nimplicated in diverse contexts from biology to materials science. However, how\na particular set of chemical reactions (chemical reaction network, CRN) would\naffect the behaviors of a phase separating system is difficult to fully predict\ntheoretically. In this paper, we analyze a mean field theory coupling CRNs to\nphase separating materials and expound on how the properties of the CRNs affect\ndifferent classes of non-equilibrium behaviors: the emergence of microphase\nseparation or of temporally oscillating patterns. We examine the problem of\nachieving microphase separated condensates by first considering tractable\nproblems and illustrating the mathematical conditions leading to microphase\nseparation. We then identify CRN motifs that are likely to yield size control\nby examining randomly generated networks and parameters. By analyzing the\nprobabilities to observe particular states, we define simple design rules of\nCRNs that lead to desired non-equilibrium behavior. We show that chemical\ninteractions generating negative feedback facilitate microphase separation,\nmoreover, we demonstrate that the parameters important for the emergence of\nmicrophase separation differ for systems with two or four components, due to\nfrustration. Our results provide guidance toward the design of self-regulating\nmaterial CRNs and provide instructions to manage the formation, dissolution,\nand organization of compartments.",
        "positive": "Predicting Complex Non-spherical Instability Shapes of Inertial\n  Cavitation Bubbles in Viscoelastic Soft Matter: Inertial cavitation in soft matter is an important phenomenon featured in a\nwide array of biological and engineering processes. Recent advances in\nexperimental, theoretical, and numerical techniques have provided access into a\nworld full of nonlinear physics, yet most of our quantitative understanding to\ndate has been centered on a spherically symmetric description of the cavitation\nprocess. However, cavitation bubble growth and collapse rarely occur in a\nperfectly symmetrical fashion, particularly in soft materials. Predicting the\nonset of dynamically arising, non-spherical instabilities has remained a\nsignificant, unresolved challenge in part due to the additional constitutive\ncomplexities introduced by the surrounding nonlinear viscoelastic solid. Here,\nwe provide a new theoretical model capable of accurately predicting the onset\nof non-spherical instability shapes of a bubble in a soft material by\nexplicitly accounting for all pertinent nonlinear interactions between the\nfluid-like cavitation bubble and the solid-like surroundings. Comparison\nagainst high-resolution experimental images from laser-induced cavitation\nevents in a polyacrylamide (PA) hydrogel show excellent agreement.\nInterestingly, and consistent with experimental findings, our model predicts\nthe emergence of various dynamic instability shapes for hoop stretch ratios\ngreater than one in contrast to most quasi-static investigations. Our new\ntheoretical framework not only provides unprecedented insight into the\ncavitation dynamics in a soft solid, but it also provides a quantitative means\nof interpreting bubble dynamics relevant to a wide array of engineering and\nmedical applications as well as natural phenomena."
    },
    {
        "anchor": "Linear viscoelasticity of entangled wormlike micelles bridged by\n  telechelic polymers : an experimental model for a double transient network: We survey the linear viscoelasticity of a new type of transient network:\nbridged wormlike micelles, whose structure has been characterized recently\n[Ramos and Ligoure, (2007)]. This composite material is obtained by adding\ntelechelic copolymers (water-soluble chains with hydrophobic stickers at each\nextremity) to a solution of entangled wormlike micelles (WM). For comparison,\nnaked WM and WM decorated by amphiphilic copolymers are also investigated.\nWhile these latter systems exhibit almost a same single ideal Maxwell behavior,\nsolutions of bridged WM can be described as two Maxwell fluids components\nblends, characterized by two markedly different characteristic times, t_fast\nand t_slow, and two elastic moduli, G_fast and G_slow, with G_fast >> G_slow.\nWe show that the slow mode is related to the viscoelasticity of the transient\nnetwork of entangled WM, and the fast mode to the network of telechelic active\nchains (i.e. chains that do not form loops but bridge two micelles). The\ndependence of the viscoelasticity with the surfactant concentration, phi, and\nthe sticker-to-surfactant molar ratio, beta, is discussed. In particular, we\nshow that G_fast is proportional to the number of active chains in the\nmaterial, phi beta. Simple theoretical expectations allow then to evaluate the\nbridges/loops ratio for the telechelic polymers.",
        "positive": "Relating unsaturated electrical and hydraulic conductivity of\n  cement-based materials: Unsaturated hydraulic ($K$) and electrical ($\\sigma_b$) conductivity are\noften considered durability indicators of cement-based materials. However, $K$\nis difficult to measure experimentally. This is due to the large pressure\nrequirements at low degrees of saturation resulting from the fine pore-size\ndistribution of cement-based materials. As a result, the commonly-used\nanalytical models, requiring calibration of $K$ from experimental data, are\noften inaccurate at low degrees of saturation. On the other hand, measuring\n$\\sigma_b$ is rather straight forward. Descriptions of the relationship between\n$\\sigma_b$ and $K$ may therefore be particularly valuable when $K$ is required.\nIn this work, we use experimental data from previous works to determine the\nfeasibility of models employing a van Genuchten-Mualem based framework to\npredict $K$ and $\\sigma_b$ -- expressions for diffusivity $D$ are also\nprovided. We then develop analytical expressions relating $K$ and $\\sigma_b$\nusing these models. It is then shown that $K = K(\\sigma_b)$ and $\\sigma_b =\n\\sigma_b(K)$ may be determined when either parameter is fully described.\nLastly, we propose a simplified model and discuss the roles of pore-size\ndistribution, saturation, pore connectivity and tortuosity in characterizing\nthe relationship between $K$ and $\\sigma_b$."
    },
    {
        "anchor": "Ultrasonic chaining of emulsion droplets: Emulsion droplets trapped in an ultrasonic levitator behave in two ways that\nsolid spheres do not: (1) Individual droplets spin rapidly about an axis\nparallel to the trapping plane, and (2) coaxially spinning droplets form long\nchains aligned with their common axis of rotation. Acoustically-organized\nchains interact hydrodynamically, either to merge into longer chains or to form\nthree-dimensional bundles of chains. Solid spheres, by contrast, form\nclose-packed planar crystals drawn together by the sound-mediated secondary\nBjerknes interaction. We demonstrate the chain-to-crystal transition with a\nmodel system in which fluid emulsion droplets can be photopolymerized into\nsolid spheres without significantly changing other material properties. The\nbehavior of this experimental system is quantitatively consistent with an\nacoustohydrodynamic model for spinning spheres in an acoustic levitator. This\nstudy therefore introduces acoustically-driven spinning as a mechanism for\nguiding self-organization of acoustically levitated matter.",
        "positive": "Molecular recognition by van der Waals interaction between polymers with\n  sequence-specific polarizabilities: We analyze van der Waals interactions between two rigid polymers with\nsequence-specific, anisotropic polarizabilities along the polymer backbones, so\nthat the dipole moments fluctuate parallel to the polymer backbones. Assuming\nthat each polymer has a quenched-in polarizability sequence which reflects, for\nexample, the polynucleotide sequence of a double-stranded DNA molecule, we\nstudy the van der Waals interaction energy between a pair of such polymers with\nrod-like structure for the cases where their respective polarizability\nsequences are (i) distinct and (ii) identical, with both zero and non-zero\ncorrelation length of the polarizability correlator along the polymer backbones\nin the latter case. For identical polymers, we find a novel $r^{-5}$ scaling\nbehavior of the van der Waals interaction energy for small inter-polymer\nseparation $r$, in contradistinction to the $r^{-4}$ scaling behavior of\ndistinct polymers, with furthermore a pronounced angular dependence favoring\nattraction between sufficiently aligned identical polymers. Such behavior can\nassist the molecular recognition between polymers."
    },
    {
        "anchor": "Confined active nematic flow in cylindrical capillaries: We use numerical modelling to study the flow patterns of an active nematic\nconfined in a cylindrical capillary, considering both planar and homeotropic\nboundary conditions. We find that active flow emerges not only along the\ncapillary axis but also within the plane of the capillary, where radial\nvortices are formed. If topological defects are imposed by the boundary\nconditions, they act as local pumps driving the flow. At higher activity we\ndemonstrate escape of the active defects and flow into the third dimension,\nindicating the importance of dimensionality in active materials. We argue that\nmeasuring the magnitude of the active flow as a function of the capillary\nradius allows determination of a value for the activity coefficient.",
        "positive": "Rough contact mechanics for graded bulk rheology: The role of\n  small-scale wavelengths on rubber friction: We present a numerical model for the prediction of the rough contact\nmechanics of a viscoelastic block, with graded rheology, in steady sliding\ncontact with a randomly rough rigid surface. In particular, we derive the\neffective surface response of a stepwise or continuously-graded block in the\nFourier domain, which is then embedded in a Fourier-based residuals molecular\ndynamic formulation of the contact mechanics. Finally we discuss on the role of\nsmall-scale wavelengths on rubber friction and contact area, and we demonstrate\nthat the rough contact mechanics exhibits effective interface properties which\nconverge to asymptotes upon increase of the small-scale roughness content, when\na realistic rheology of the confinement is taken into account."
    },
    {
        "anchor": "Transiently delocalized states enhance hole mobility in organic\n  molecular semiconductors: There is compelling evidence that charge carriers in organic semiconductors\n(OSs) self-localize in nano-scale space because of dynamic disorder. Yet, some\nOSs, in particular recently emerged high-mobility organic molecular crystals,\nfeature reduced mobility at increasing temperature, a hallmark for delocalized\nband transport. Here we present the temperature-dependent mobility in two\nrecord-mobility OSs: DNTT (dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]-thiophene),\nand its alkylated derivative, C8-DNTT-C8. By combining terahertz\nphotoconductivity measurements with fully atomistic non-adiabatic molecular\ndynamics simulations, we show that while both crystals display a power-law\ndecrease of the mobility (\\mu) with temperature (T, following: \\mu \\propto\nT^(-n)), the exponent n differs substantially. Modelling provides n values in\ngood agreement with experiments and reveals that the differences in the falloff\nparameter between the two chemically closely related semiconductors can be\ntraced to the delocalization of the different states thermally accessible by\ncharge carriers, which in turn depends on the specific electronic band\nstructure of the two systems. The emerging picture is that of holes surfing on\na dynamic manifold of vibrationally-dressed extended states with a\ntemperature-dependent mobility that provides a sensitive fingerprint for the\nunderlying density of states.",
        "positive": "Origin of translocation barriers for polyelectrolyte chains: For single-file translocations of a charged macromolecule through a narrow\npore, the crucial step of arrival of an end at the pore suffers from free\nenergy barriers, arising from changes in intrachain electrostatic interaction,\ndistribution of ionic clouds and solvent molecules, and conformational entropy\nof the chain. All contributing factors to the barrier in the initial stage of\ntranslocation are evaluated by using the self-consistent field theory for the\npolyelectrolyte and the coupled Poisson-Boltzmann description for ions, without\nradial symmetry. The barrier is found to be essentially entropic, due to\nconformational changes. For moderate and high salt concentrations, the barriers\nfor the polyelectrolyte chain are quantitatively equivalent to that of\nuncharged self-avoiding walks. Electrostatic effects are shown to increase the\nfree energy barriers, but only slightly. The degree of ionization,\nelectrostatic interaction strength, decreasing salt concentration and the\nsolvent quality all result in increases in the barrier."
    },
    {
        "anchor": "Effect of the electrical double layer on the electrical conductivity of\n  suspensions: We study the role of the electrical double layer (EDL) in the formation of\nthe quasistatic electrical conductivity of suspensions of nanosized particles.\nA suspension is viewed as a system of hard-core--penetrable-shell particles.\nThe shells are electrically inhomogeneous, with a radially symmetrical\nconductivity profile. It is assumed that the real microstructure of the\nsuspension can be reflected in terms of this profile and also the rule of\ndominance for overlapping regions that the local conductivity in the system is\ndetermined by the nearest particle. Using our earlier rigorous results for\nsystems with this morphology, we derive general integral relations for the\ndesired conductivity which incorporate the effect of the EDL and make it\npossible to look into the contributions from its different parts and\nparameters. Specific features, internal consistency, and flexibility of the\nmodel are demonstrated by further elaborating it to describe experimental data\nfor latex suspensions in aqueous electrolyte solutions with high ionic\nstrength.",
        "positive": "Escape transition of a polymer chain from a nanotube: how to avoid\n  spurious results by use of the force-biased pruned-enriched Rosenbluth\n  algorithm: A polymer chain containing $N$ monomers confined in a finite cylindrical tube\nof diameter $D$ grafted at a distance $L$ from the open end of the tube may\nundergo a rather abrupt transition, where part of the chain escapes from the\ntube to form a \"crown-like\" coil outside of the tube. When this problem is\nstudied by Monte Carlo simulation of self-avoiding walks on the simple cubic\nlattice applying a cylindrical confinement and using the standard\npruned-enriched Rosenbluth method (PERM), one obtains spurious results,\nhowever: with increasing chain length the transition gets weaker and weaker,\ndue to insufficient sampling of the \"escaped\" states, as a detailed analysis\nshows. In order to solve this problem, a new variant of a biased sequential\nsampling algorithm with re-sampling is proposed, force-biased PERM: the\ndifficulty of sampling both phases in the region of the first order transition\nwith the correct weights is treated by applying a force at the free end pulling\nit out of the tube. Different strengths of this force need to be used and\nreweighting techniques are applied. Using rather long chains (up to N=18000)\nand wide tubes (up to D=29 lattice spacings), the free energy of the chain, its\nend-to-end distance, the number of \"imprisoned\" monomers can be estimated, as\nwell as the order parameter and its distribution. It is suggested that this new\nalgorithm should be useful for other problems involving state changes of\npolymers, where the different states belong to rather disjunct \"valleys\" in the\nphase space of the system."
    },
    {
        "anchor": "Conductivity and permittivity of dispersed systems with penetrable\n  particle-host interphase: A model for the study of the effective quasistatic conductivity and\npermittivity of dispersed systems with particle-host interphase, within which\nmany-particle polarization and correlation contributions are effectively\nincorporated, is presented. The structure of the system's components, including\nthe interphase, is taken into account through modelling their low-frequency\ncomplex permittivity profiles. The model describes, among other things, a\npercolation-type behavior of the effective conductivity, accompanied by a\nconsiderable increase in the real part of the effective complex permittivity.\nThe percolation threshold location is determined mainly by the thickness of the\ninterphase. The \"double\" percolation effect is predicted. The results are\ncontrasted with experiment.",
        "positive": "The effect of curvature on the diffusion of colloidal bananas: Anisotropic colloidal particles exhibit complex dynamics which play a crucial\nrole in their functionality, transport and phase behaviour. In this work, we\ninvestigate the two-dimensional diffusion of smoothly curved colloidal rods --\nalso known as colloidal bananas -- as a function of their opening angle,\n{\\alpha}. We measure the translational and rotational diffusion coefficients of\nthe particles with opening angles ranging from 0{\\deg} (straight rods) to\nnearly 360{\\deg}(closed rings). In particular, we find that the anisotropic\ndiffusion of the particles varies non-monotonically with their opening angle\nand that the axis of fastest diffusion switches from the long to the short axis\nof the particles when {\\alpha}>180{\\deg}.\n  We also find that the rotational diffusion coefficient of nearly closed rings\nis approximately an order of magnitude higher than that of straight rods of the\nsame length. Finally, we show that the experimental results are consistent with\nSlender Body Theory, indicating that the dynamical behavior of the particles\narises primarily from their local drag anisotropy. These results highlight the\nimpact of curvature on the Brownian Motion of elongated colloidal particles,\nwhich must be taken into account when seeking to understand the behaviour of\ncurved colloidal particles."
    },
    {
        "anchor": "Spin polarizability of a trapped superfluid Fermi gas: The polarization produced by the relative displacement of the potentials\ntrapping two spin species of a dilute Fermi gas with $N_\\ua=N_\\da$ is\ncalculated at unitarity by assuming phase separation between the superfluid and\na spin polarized phase at zero temperature. Due to the energy cost associated\nwith pair breaking, the dipole magnetic polarizability vanishes in the linear\nlimit and exhibits important deviations from the ideal gas behaviour even for\ndisplacements of the order of the size of the atomic cloud. The magnetic\nbehaviour in the presence of different trapping frequencies for the two spin\nspecies is also discussed.",
        "positive": "Crystal Nucleation of Colloidal Suspensions under Shear: We use Brownian Dynamics simulations in combination with the umbrella\nsampling technique to study the effect of shear flow on homogeneous crystal\nnucleation. We find that a homogeneous shear rate leads to a significant\nsuppression of the crystal nucleation rate and to an increase of the size of\nthe critical nucleus. A simple, phenomenological extension of classical\nnucleation theory accounts for these observations. The orientation of the\ncrystal nucleus is tilted with respect to the shear direction."
    },
    {
        "anchor": "Microstructural model for cyclic hardening in F-actin networks\n  crosslinked by $\u03b1$-actinin: The rheology of F-actin networks has attracted a great attention during the\nlast years. In order to gain a complete understanding of the rheological\nproperties of these novel materials, it is necessary the study in a large\ndeformations regime to alter their internal structure. In this sense, Schmoller\net al. 2010 showed that the reconstituted networks of F-actin crosslinked with\n$\\alpha$-actinin unexpectedly harden when they are subjected to a cyclical\nshear. This observation contradicts the expected Mullins effect observed in\nmost soft materials, such as rubber and living tissues, where a pronounced\nsoftening is observed when they are cyclically deformed.\n  We think that the key to understand this stunning effect is the gelation\nprocess. To define it, the most relevant constituents are the chemical\ncrosslinks -$\\alpha$-actinin-, the physical crosslinks -introduced by the\nentanglement of the semiflexible network- and the interaction between them. As\na consequence of this interaction, a pre-stressed network emerges and\nintroduces a feedback effect, where the pre-stress also regulates the adhesion\nenergy of the $\\alpha$-actinin, setting the structure in a metastable reference\nconfiguration. Therefore, the external loads and the evolvement of the trapped\nstress drive the microstructural changes during the cyclic loading protocol. In\nthis work, we propose a micromechanical model into the framework of nonlinear\ncontinuum mechanics. The mechanics of the F-actin filaments is modeled using\nthe wormlike chain model for semiflexible filaments and the gelation process is\nmodeled as mesoscale dynamics for the $\\alpha$-actinin and physical\ncrosslink.The model has been validated with reported experimental results.",
        "positive": "Attractive double-layer forces between neutral hydrophobic and neutral\n  hydrophilic surfaces: The interaction between surface patches of proteins with different surface\nproperties has a vital role to play driving conformational changes of proteins\nin different salt solutions. We demonstrate the existence of ion-specific\nattractive double-layer forces between neutral hydrophobic and hydrophilic\nsurfaces in the presence of certain salt solutions. This is done by solving a\ngeneralized Poisson-Boltzmann equation for two unequal surfaces. In the\ncalculations we utilize parameterized ion-surface-potentials and\ndielectric-constant-profiles deduced from recent non-primitive-model molecular\ndynamics (MD) simulations that account partially for molecular structure and\nhydration effects."
    },
    {
        "anchor": "Stress relaxation above and below the jamming transition: We numerically investigate stress relaxation in soft athermal disks to reveal\ncritical slowing down when the system approaches the jamming point. The\nexponents describing the divergence of the relaxation time differ dramatically\ndepending on whether the transition is approached from the jammed or unjammed\nphase. This contrasts sharply with conventional dynamic critical scaling\nscenarios, where a single exponent characterizes both sides. We explain this\nsurprising difference in terms of the vibrational density of states (vDOS),\nwhich is a key ingredient of linear viscoelastic theory. The vDOS exhibits an\nextra slow mode that emerges below jamming, which we utilize to demonstrate the\nanomalous exponent below jamming.",
        "positive": "Theory of rheology and aging of protein condensates: Biological condensates are assemblies of proteins and nucleic acids that form\nmembraneless compartments in cells and play essential roles in cellular\nfunctions. In many cases they exhibit the physical properties of liquid\ndroplets that coexist in a surrounding fluid. Recently, quantitative studies on\nthe material properties of biological condensates have become available,\nrevealing complex material properties. In vitro experiments have shown that\nprotein condensates exhibit time dependent material properties, similar to\naging in glasses. To understand this phenomenon from a theoretical perspective,\nwe develop a rheological model based on the physical picture of protein\ndiffusion and stochastic binding inside condensates. The complex nature of\nprotein interactions is captured by a distribution of binding energies,\nincorporated in a trap model originally developed to study glass transitions.\nOur model can describe diffusion of constituent particles, as well as the\nmaterial response to time-dependent forces, and it recapitulates the age\ndependent relaxation time of Maxwell glass observed experimentally both in\nactive and passive rheology. We derive a generalized fluctuation-response\nrelations of our model in which the relaxation function does not obey time\ntranslation invariance. Our study sheds light on the complex material\nproperties of biological condensates and provides a theoretical framework for\nunderstanding their aging behavior."
    },
    {
        "anchor": "Morphology and mobility of synthetic colloidal aggregates: The relationship between geometric and dynamic properties of fractal-like\naggregates is studied in the continuum mass and momentum-transfer regimes. The\nsynthetic aggregates were generated by a cluster-cluster aggregation algorithm.\nThe analysis of their morphological features suggests that the fractal\ndimension is a descriptor of a cluster's large-scale structure, whereas the\nfractal prefactor is a local-structure indicator. For a constant fractal\ndimension, the prefactor becomes also an indicator of a cluster's shape\nanisotropy. The hydrodynamic radius of orientationally averaged aggregates was\ncalculated via molecule-aggregate collision rates determined from the solution\nof a Laplace equation. An empirical expression that relates the aggregate\nhydrodynamic radius to its radius of gyration and the number of primary\nparticles is proposed. The suggested expression depends only on geometrical\nquantities, being independent of statistical (ensemble-averaged) properties\nlike the fractal dimension and prefactor. Hydrodynamic radius predictions for a\nvariety of fractal-like aggregates are in very good agreement with predictions\nof other methods and literature values. Aggregate dynamic shape factors and\nDLCA individual monomer hydrodynamic shielding factors are also calculated.",
        "positive": "Theory of the isotropic-nematic transition in dispersions of\n  compressible rods: We theoretically study the nematic ordering transition of rods that are able\nto elastically adjust their mutually excluded volumes. The model rods, which\nconsist of a hard core surrounded by a deformable shell, mimic the structure of\npolymer-coated, rod-like fd virus particles that have recently been the object\nof experimental study [K.~Purdy et al., Phys. Rev. Lett. \\textbf{94}, 057801\n(2005)]. We find that fluids of such soft rods exhibit an isotropic-nematic\nphase transition at a density higher than that of the corresponding hard-rod\nsystem of identical diameter, and that at coexistence the order parameter of\nthe nematic phase depends non monotonically on the elastic properties of the\npolymer coating. For binary mixtures of hard and soft rods, the topology of the\nphase diagram turns out to depend sensitively on the elasticity of shell. The\nlower nematic-nematic critical point, discovered in mixtures of bare and\npolymer-coated fd virus particles, is not reproduced by the theory."
    },
    {
        "anchor": "Viscous-like forces control the impact response of shear-thickening\n  dense suspensions: We experimentally and theoretically study impacts into dense cornstarch and\nwater suspensions. We vary impact speed as well as intruder size, shape, and\nmass, and we characterize the resulting dynamics using high-speed video and an\nonboard accelerometer. We numerically solve previously proposed models, most\nnotably the added-mass model as well as a class of {viscous-like} models. In\nthe {viscous-like models}, the intruder dynamics are dominated by {large,\nviscous-like forces} at the boundary of the jammed front {where large shear\nrates and accompanying large viscosities are present.} We find that our\nexperimental data are consistent with this class of models and inconsistent\nwith the added mass model. Our results strongly suggest that the added-mass\nmodel, which is the dominant model for understanding the dynamics of impact\ninto shear-thickening dense suspensions, should be updated to include these\nviscous-like forces.",
        "positive": "Localized states in passive and active phase-field-crystal models: The passive conserved Swift-Hohenberg equation (or phase-field-crystal [PFC]\nmodel) corresponds to a gradient dynamics for a single order parameter field\nrelated to density. It provides a simple microscopic description of the\nthermodynamic transition between liquid and crystalline states. In addition to\nspatially extended periodic structures, the model describes a large variety of\nsteady spatially localized structures. In appropriate bifurcation diagrams the\ncorresponding solution branches exhibit characteristic slanted homoclinic\nsnaking. In an active PFC model, encoding for instance the active motion of\nself-propelled colloidal particles, the gradient dynamics structure is broken\nby a coupling between density and an additional polarization field. Then,\nresting and traveling localized states are found with transitions characterized\nby parity-breaking drift bifurcations. Here, we first briefly review the\nsnaking behavior of localized states in passive and active PFC models before\ndiscussing the bifurcation behavior of localized states in systems of (i) two\ncoupled passive PFC equations described by common gradient dynamics, (ii) two\ncoupled passive PFC where the coupling breaks the gradient dynamics structure,\nand (iii) a passive PFC coupled to an active PFC."
    },
    {
        "anchor": "Fluids with competing interactions: II. Validating a free energy model\n  for equilibrium cluster size: Using computer simulations, we validate a simple free energy model that can\nbe analytically solved to predict the equilibrium size of self-limiting\nclusters of particles in the fluid state governed by a combination of\nshort-range attractive and long-range repulsive pair potentials. The model is a\nsemi-empirical adaptation and extension of the canonical free energy-based\nresult due to Groenewold and Kegel [J. Phys. Chem. B, 105 (2001)], where we use\nnew computer simulation data to systematically improve the cluster-size\nscalings with respect to the strengths of the competing interactions driving\naggregation. We find that one can adapt a classical nucleation like theory for\nsmall energetically-frustrated aggregates provided one appropriately accounts\nfor a size-dependent, microscopic energy penalty of interface formation, which\nrequires new scaling arguments. This framework is verified in part by\nconsidering the extensive scaling of intracluster bonding, where we uncover a\nsuperlinear scaling regime distinct from (and located between) the known\nregimes for small and large aggregates. We validate our model based on\ncomparisons against approximately 100 different simulated systems comprising\ncompact spherical aggregates with characteristic (terminal) sizes between six\nand sixty monomers, which correspond to wide ranges in\nexperimentally-controllable parameters.",
        "positive": "Equilibrium Chemical Engines: An equilibrium reversible cycle with a certain engine to transduce the energy\nof any chemical reaction into mechanical energy is proposed. The efficiency for\nchemical energy transduction is also defined so as to be compared with Carnot\nefficiency. Relevance to the study of protein motors is discussed. KEYWORDS:\nChemical thermodynamics, Engine, Efficiency, Molecular machine."
    },
    {
        "anchor": "Effective shape and phase behaviour of short charged rods: We explicitly calculate the orientation-dependent second virial coefficient\nof short charged rods in an electrolytic solvent, assuming the rod-rod\ninteractions to be a pairwise sum of hard-core and segmental screened-Coulomb\nrepulsions. From the parallel and isotropically averaged second virial\ncoefficient, we calculate the effective length and diameter of the rods, for\ncharges and screening lengths that vary over several orders of magnitude. Using\nthese effective dimensions, we determine the phase diagram, where we\ndistinguish a low-charge and strong-screening regime with a liquid crystalline\nnematic and smectic phase, and a high-charge and weak-screening regime with a\nplastic crystal phase in the phase diagram.",
        "positive": "Self-energy limited ion transport in sub-nanometer channels: The current-voltage characteristics of the alpha-Hemolysin protein pore\nduring the passage of single-stranded DNA under varying ionic strength, C, are\nstudied experimentally. We observe strong blockage of the current, weak\nsuper-linear growth of the current as a function of voltage, and a minimum of\nthe current as a function of C. These observations are interpreted as the\nresult of the ion electrostatic self-energy barrier originating from the large\ndifference in the dielectric constants of water and the lipid bilayer. The\ndependence of DNA capture rate on C also agrees with our model."
    },
    {
        "anchor": "The size of the Sun: Why does the Sun have a radius around 696000~km? We will see in this article\nthat dimensional arguments can be used to understand the size of the Sun and of\na few other things along the way. These arguments are not new and can be found\nscattered in textbooks. They are presented here in a succinct way in order to\nbetter confront the kinematic and mechanical viewpoints on size. We derive and\ncompare a number of expressions for the size of the Sun and relate large and\nsmall scales. We hope that such presentation will be useful to students,\ninstructors and researchers alike.",
        "positive": "Crumpling for Energy: Modeling Generated Power from the Crumpling of\n  Polymer Piezoelectric Foils for Wearable Electronics: We consider possibility of embedding large sheets of polymer piezoelectrics\nin clothing for sensing and energy harvesting for wearable electronic\napplications. Power is generated by the crumpling of clothes due to human body\nmovements. From the mechanics of a gently crumpled foil we develop theoretical\nmodels and scaling laws for the open circuit voltage and short circuit current\nand verify via experiments. It is concluded that stretching is the dominant\ncharge generation mechanism with the open circuit voltage and short circuit\ncurrent scaling as $l^{i}$ and $l^{i-1}(\\mbox{d}l/\\mbox{d}t)$, respectively\nwith $1\\leq i\\leq 4/3$ and $l$ the height of the crumple cone."
    },
    {
        "anchor": "Growth of solid conical structures during multistage drying of sessile\n  poly(ethylene oxide) droplets: Sessile droplets of aqueous poly(ethylene oxide) solution, with average\nmolecular weight of 100 kDa, are monitored during evaporative drying at ambient\nconditions over a range of initial concentrations $c_0$. For all droplets with\n$c_0 \\geq 3%$, central conical structures, which can be hollow and nearly 50%\ntaller than the initial droplet, are formed during a growth stage. Although the\nformation of superficially similar structures has been explained for\nglass-forming polymers using a skin-buckling model which predicts the droplet\nto have constant surface area during the growth stage (L. Pauchard and C.\nAllain, Europhys. Lett., 2003, 62, 897-903), we demonstrate that this model is\nnot applicable here as the surface area is shown to increase during growth for\nall $c_0$. We interpret our experimental data using a proposed drying and\ndeposition process comprising the four stages: pinned drying; receding contact\nline; bootstrap growth, during which the liquid droplet is lifted upon\nfreshly-precipitated solid; and late drying. Additional predictions of our\nmodel, including a criterion for predicting whether a conical structure will\nform, compare favourably with observations. We discuss how the specific\nchemical and physical properties of PEO, in particular its amphiphilic nature,\nits tendency to form crystalline spherulites rather than an amorphous glass at\nhigh concentrations and its anomalous surface tension values for MW = 100 kDa\nmay be critical to the observed drying process.",
        "positive": "Sorting of particles suspended in whole blood: An important step in diagnostics is the isolation of specific cells and\nmicroorganisms of interest from blood. Since such bioparticles are often\npresent at very low concentrations, throughput needs to be as high as possible.\nIn addition, to ensure simplicity, a minimum of sample preparation is\nimportant. Therefore, sorting schemes that function for whole blood are highly\ndesirable. Deterministic lateral displacement (DLD) has proven to be very\nprecise and versatile in terms of a wide range of sorting parameters. To better\nunderstand how DLD performs for blood as the hematocrit increases, we have\nperformed measurements and simulations for spherical particles in the\nmicrometer range moving through DLD arrays for different flow velocities and\nhematocrits ranging from pure buffer to whole blood. We find that the\nseparation function of the DLD array is sustained, even though blood cells\nintroduce a shift in the trajectories and a significant dispersion for\nparticles that are close to the critical size in the device. Simulations\nqualitatively replicate our experimental observations and help us identify\nfundamental mechanisms for the effect of hematocrit on the performance of the\nDLD device."
    },
    {
        "anchor": "Critical Decay at Higher-Order Glass-Transition Singularities: Within the mode-coupling theory for the evolution of structural relaxation in\nglass-forming systems, it is shown that the correlation functions for density\nfluctuations for states at A_3- and A_4-glass-transition singularities can be\npresented as an asymptotic series in increasing inverse powers of the logarithm\nof the time t: $\\phi(t)-f\\propto \\sum_i g_i(x)$, where $g_n(x)=p_n(\\ln x)/x^n$\nwith p_n denoting some polynomial and x=ln (t/t_0). The results are\ndemonstrated for schematic models describing the system by solely one or two\ncorrelators and also for a colloid model with a square-well-interaction\npotential.",
        "positive": "Unwrapping of DNA-protein complexes under external stretching: A DNA-protein complex modelled by a semiflexible chain and an attractive\nspherical core is studied in the situation when an external stretching force is\nacting on one end monomer of the chain while the other end monomer is kept\nfixed in space. Without stretching force, the chain is wrapped around the core.\nBy applying an external stretching force, unwrapping of the complex is induced.\nWe study the statics and the dynamics of the unwrapping process by computer\nsimulation and simple phenomenological theory. We find two different scenarios\ndepending on the chain stiffness: For a flexible chain, the extension of the\ncomplex scales linearly with the external force applied. The sphere-chain\ncomplex is disordered, i.e. there is no clear winding of the chain around the\nsphere. For a stiff chain, on the other hand, the complex structure is ordered,\nwhich is reminiscent to nucleosome. There is a clear winding number and the\nunwrapping process under external stretching is discontinuous with jumps of the\ndistance-force curve. This is associated to discrete unwinding processes of the\ncomplex. Our predictions are of relevance for experiments, which measure\nforce-extension curves of DNA-protein complexes, such as nucleosome, using\noptical tweezers."
    },
    {
        "anchor": "The apparent roughness of a sand surface blown by wind from an\n  analytical model of saltation: We present an analytical model of aeolian sand transport. The model\nquantifies the momentum transfer from the wind to the transported sand by\nproviding expressions for the thickness of the saltation layer and the apparent\nsurface roughness. These expressions are derived from basic physical principles\nand a small number of assumptions. The model further predicts the sand\ntransport rate (mass flux) and the impact threshold (the smallest value of the\nwind shear velocity at which saltation can be sustained). We show that, in\ncontrast to previous studies, the present model's predictions are in very good\nagreement with a range of experiments, as well as with numerical simulations of\naeolian saltation. Because of its physical basis, we anticipate that our model\nwill find application in studies of aeolian sand transport on both Earth and\nMars.",
        "positive": "A stochastic model for the stepwise motion in actomyosin dynamics: A jump-diffusion process is proposed to describe the displacements performed\nby single myosin heads along actin filaments during the rising phases. The\nprocess consists of the superposition of a Wiener and a jump process, with\njumps originated by sequences of Poisson-distributed energy-supplying pulses.\nIn a previous paper, the amplitude of the jumps was described by a mixture of\ntwo Gaussian distributions. To embody the effects of ATP hydrolysis, we now\nrefine such a model by assuming that the jumps' amplitude is described by a\nmixture of three Gaussian distributions. This model has been inspired by the\nexperimental data of T. Yanagida and his co-workers concerning observations at\nsingle molecule processes level."
    },
    {
        "anchor": "A smooth cascade of wrinkles at the edge of a floating elastic film: The mechanism by which a patterned state accommodates the breaking of\ntranslational symmetry by a phase boundary or a sample wall has been addressed\nin the context of Landau branching in type-I superconductors, refinement of\nmagnetic domains, and compressed elastic sheets. We explore this issue by\nstudying an ultrathin polymer sheet floating on the surface of a fluid,\ndecorated with a pattern of parallel wrinkles. At the edge of the sheet, this\ncorrugated profile meets the fluid meniscus. Rather than branching of wrinkles\ninto generations of ever-smaller sharp folds, we discover a smooth cascade in\nwhich the coarse pattern in the bulk is matched to fine structure at the edge\nby the continuous introduction of discrete, higher wavenumber Fourier modes.\nThe observed multiscale morphology is controlled by a dimensionless parameter\nthat quantifies the relative strength of the edge forces and the rigidity of\nthe bulk pattern.",
        "positive": "Non-additivity of van der Waals forces on liquid surfaces: We present an approach for modeling nanoscale wetting and dewetting of liquid\nsurfaces that exploits recently developed, sophisticated techniques for\ncomputing van der Waals (vdW) or (more generally) Casimir forces in arbitrary\ngeometries. We solve the variational formulation of the Young--Laplace equation\nto predict the equilibrium shapes of fluid--vacuum interfaces near solid\ngratings and show that the non-additivity of vdW interactions can have a\nsignificant impact on the shape and wetting properties of the liquid surface,\nleading to very different surface profiles and wetting transitions compared to\npredictions based on commonly employed additive approximations, such as Hamaker\nor Derjaguin approximations."
    },
    {
        "anchor": "Adsorption of cationic polyions to a hydrophobic surface in the presence\n  of Hofmeister salts: We study, using extensive Monte Carlos simulations, the behavior of cationic\npolyelectrolytes near hydrophobic surfaces in solutions containing Hofmeister\nsalts. The Hofmeister anions are divided into kosmotropes and chaotropes. Near\na hydrophobic surface, the chaotropes lose their solvation sheath and become\npartially adsorbed to the interface, while the kosmotropes remain strongly\nhydrated and are repelled from the interface. If the polyelectrolyte solution\ncontains chaotropic anions, a significant adsorption of polyions to the surface\nis also observed. On the other hand, the kosmotropic anions have only a small\ninfluence on the polyion adsorption. These findings can have important\nimplications for exploring the antibacterial properties of cationic\npolyelectrolytes.",
        "positive": "Polymers in disordered environments: A brief review of our recent studies aiming at a better understanding of the\nscaling behaviour of polymers in disordered environments is given. The main\nemphasis is on a simple generic model where the polymers are represented by\n(interacting) self-avoiding walks and the disordered environment by critical\npercolation clusters. The scaling behaviour of the number of conformations and\ntheir average spatial extent as a function of the number of monomers and the\nassociated critical exponents $\\gamma$ and $\\nu$ are examined with two\ncomplementary approaches: numerical chain-growth computer simulations using the\nPERM algorithm and complete enumerations of all possible polymer conformations\nemploying a recently developed very efficient exact counting method."
    },
    {
        "anchor": "Optimum dissipation by cruising in dense suspensions: Dense suspensions tend to shear jam at large packing fractions. However, it\nhas recently been shown that various oscillation protocols can unjam as well as\nreduce viscosity and dissipation. In this numerical work, we ask ourselves what\nis the optimum shear protocol in terms of dissipation. We show that many\ncruising protocols' dissipation are similar to shear protocols with a steady\nprimary shear and superimposed cross oscillations, even though the latter's\nviscosity reduction is more considerable. Furthermore, we find that alternating\nbetween primary and perpendicular oscillations yields a much higher dissipation\nthan the two protocols mentioned above, yet has similar viscosity as the\ncross-oscillatory one. While self-organization has been shown to minimize\nviscosity, our findings challenge the idea that random organization is the\nunderlying mechanism for reducing dissipation. Instead, shear ``fragility''\ncombined with geometry seems to be the key ingredients, which explains the\ncounter-intuitive decoupling of the minima of viscosity and dissipation for the\ncruising protocol. This work paves the way for a new class of highly-energy\nefficient flow protocols.",
        "positive": "Self-Assembly in Mixtures of Amphiphilic Polymers and Surfactants: We present a model for the joint self-assembly of amphiphilic polymers and\nsmall amphiphilic molecules (surfactants) in a dilute aqueous solution. The\npolymer is assumed to consist of a hydrophilic backbone and a large number of\nhydrophobic side groups. Preference of the surfactant to bind to hydrophobic\nmicrodomains along the polymer induces an effective attraction between bound\nsurfactants. This leads to two distinct binding regimes depending on a single\nphysical parameter, \\epsilon, which represents the ratio between\nsurfactant-polymer affinity and polymer hydrophobicity. For small \\epsilon the\nbinding is non-cooperative, whereas for large \\epsilon it becomes strongly\ncooperative at a well-defined critical aggregation concentration. Our findings\nare in accord with observations on diverse experimental systems."
    },
    {
        "anchor": "Shock Waves in Weakly Compressed Granular Media: We experimentally probe nonlinear wave propagation in weakly compressed\ngranular media, and observe a crossover from quasi-linear sound waves at low\nimpact, to shock waves at high impact. We show that this crossover grows with\nthe confining pressure $P_0$, whereas the shock wave speed is independent of\n$P_0$ --- two hallmarks of granular shocks predicted recently. The shocks\nexhibit powerlaw attenuation, which we model with a logarithmic law implying\nthat local dissipation is weak. We show that elastic and potential energy\nbalance in the leading part of the shocks.",
        "positive": "Effect of chain stiffness on the competition between crystallization and\n  glass-formation in model colloidal polymers: We map out the solid-state morphologies formed by model soft-pearl-necklace\npolymers as a function of bending stiffness $k_b$ spanning the range from fully\nflexible to rodlike chains. The ratio of Kuhn length to bead diameter\n($l_K/r_0$) increases monotonically with increasing $k_b$ and yields a\none-parameter model that relates chain shape to bulk morphology and yields\ninsights into the packing of anisotropic particles. In the flexible limit,\nmonomers occupy the sites of close-packed crystallites while chains retain\nrandom-walk-like order. In the rodlike limit, nematic chain ordering typical of\nlamellar precursors coexists with close-packing. At intermediate values of\nbending stiffness the competition between random-walk-like and nematic chain\nordering produces glass-formation; the range of $k_b$ over which this occurs\nincreases with the thermal cooling rate $|\\dot{T}|$ implemented in our\nmolecular dynamics simulations. Finally, values of $k_b$ between the\nglass-forming and rodlike ranges produce complex ordered phases such as\nclose-packed spirals. Our results should prove useful for rational design of\ndense colloidal-polymer phases with desired morphologies."
    },
    {
        "anchor": "On finite size effects, ensemble choice and force influence in\n  dissipative particle dynamics simulations: The influence of finite size effects, choice of statistical ensemble and\ncontribution of the forces in numerical simulations using the dissipative\nparticle dynamics (DPD) model are revisited here. Finite size effects in stress\nanisotropy, interfacial tension and dynamic viscosity are computed and found to\nbe minimal with respect to other models. Additionally, the choice of ensemble\nis found to be of fundamental importance for the accurate calculation of\nproperties such as the solvation pressure, especially for relatively small\nsystems. Lastly, the contribution of the random, dissipative and conservative\nforces that make up the DPD model in the prediction of properties of simple\nliquids such as the pressure is studied as well. Some tricks of the trade are\nprovided, which may be useful for those carrying out high-performance numerical\nsimulations using the DPD model.",
        "positive": "Influence of the particle shape on the equilibrium morphologies of\n  supracolloidal magnetic filaments: We investigate the equilibrium morphologies of linear and ring-shaped\nmagnetic filaments made from crosslinked ferromagnetic spherical or ellipsoidal\ncolloidal particles. Using Langevin dynamics simulations, we calculate the\nradius of gyration and total magnetic moment of a single filament at zero field\nand different temperatures, analyzing the influence of the particles shape, the\nstrength of their magnetic moment and the filament length. Our results show\nthat, among such parameters, the shape of the particles has the strongest\nqualitative impact on the equilibrium behavior of the filaments."
    },
    {
        "anchor": "Experiments demonstrate that the null space of the rigidity matrix\n  determines grain motion during vibration-induced compaction: Using a previously developed experimental method to reduce friction in\nmechanically stable packings of disks, we find that frictional packings form\ntree-like structures of geometrical families that lie on reduced dimensional\nmanifolds in configuration space. Each branch of the tree begins at a point in\nconfiguration space with an isostatic number of contacts and spreads out to\nsequentially higher dimensional manifolds as the number of contacts are\nreduced. We find that gravitational deposition of disks produces an initially\nunder-coordinated packing stabilized by friction on a high-dimensional\nmanifold. Using short vibration bursts to reduce friction, we compact the\nsystem through many stable configurations with increasing contact number and\ndecreasing dimensionality until the system reaches an isostatic frictionless\nstate. We find that this progression can be understood as the system moving\nthrough the null-space of the rigidity matrix defined by the interparticle\ncontact network in the direction of the gravitational force. We suggest that\nthis formalism can also be used to explain the evolution of frictional packings\nunder other forcing conditions.",
        "positive": "Dynamical yield criterion for granular matter from first principles: We investigate, using a recently developed model of liquid state theory\ndescribing the rheology of dense granular flows, how a yield stress appears in\ngranular matter at the yielding transition. Our model allows us to predict an\nanalytical equation of the corresponding dynamical yield surface, which is\ncompared to usual models of solid fracture. In particular, this yield surface\ninterpolates between the typical failure behaviors of soft and hard materials.\nThis work also underlines the central role played by the effective friction\ncoefficient at the yielding transition."
    },
    {
        "anchor": "High-energy velocity tails in uniformly heated granular materials: We experimentally investigate the velocity distributions of quasi\ntwo-dimensional granular materials, which are homogeneously driven, i.e.\nuniformly heated, by an electromagnetic vibrator, where the translational\nvelocity and the rotation of a single particle are Gaussian and independent. We\nobserve the non-Gaussian distributions of particle velocity, with the\ndensity-independent high-energy tails characterized by an exponent of\n$\\beta=1.50\\pm0.03$ for volume fractions of $0.111\\le\\phi\\le0.832$, covering a\nwide range of structures and dynamics. Surprisingly, our results are in\nexcellent agreement with the prediction of the kinetic theories of granular\ngas, even for an extremely high volume fraction of $\\phi=0.832$ where the\ngranular material forms a crystalline solid. Our experiment reveals that the\ndensity-independent high-energy velocity tails of $\\beta=1.50$ are a\nfundamental property of uniformly heated granular matter.",
        "positive": "Arrested coalescence of viscoelastic droplets: Ellipsoid shape effects\n  and restructuring: The stable configurations formed by two viscoelastic, ellipsoid-shaped\ndroplets during their arrested coalescence has been investigated using\nmicromanipulation experiments. Ellipsoidal droplets are produced by\nmillifluidic emulsification of petrolatum into a yield stress fluid that\npreserves their elongated shape. The liquid meniscus between droplets can\ntransmit stress and instigate movement of the droplets, from their initial\nrelative position, in order to minimize doublet surface energy. The action of\nthe liquid meniscus causes the ellipsoidal droplets to undergo rolling and\nrestructuring events because of their unique ellipsoid shape and associated\nvariation in surface curvature. The final configuration of the droplets is\nshown to be controlled by the balance between interfacial Laplace pressure and\ninternal elasticity, as well as a constraint force that resists complete\nminimization of surface energy. Geometric and surface energy calculations are\nused to map the possible and most likely configurations of the droplet pairs.\nExperimental deviations from the calculations indicate the magnitude and\npotential origin of the constraint force resisting full equilibration. Droplet\naspect ratio and elasticity are both shown to influence the degree of\nrestructuring and stability of the droplets at energy extrema. Higher aspect\nratios drive greater restructuring and better agreement with final doublet\nconfigurations predicted by energy minimization. Lower elasticity droplets\nundergo secondary deformations at high aspect ratios, further broadening the\nspace of possible morphologies."
    },
    {
        "anchor": "Nuclear quantum effects in water: In this work, a path integral Car-Parrinello molecular dynamics simulation of\nliquid water is performed. It is found that the inclusion of nuclear quantum\neffects systematically improves the agreement of first principles simulations\nof liquid water with experiment. In addition, the proton momentum distribution\nis computed utilizing a recently developed open path integral molecular\ndynamics methodology. It is shown that these results are in good agreement with\nneutron Compton scattering data for liquid water and ice.",
        "positive": "Self-organized swimming with odd elasticity: We theoretically investigate self-oscillating waves of an active material,\nwhich have recently been introduced as a non-symmetric part of the elastic\nmoduli, termed odd elasticity. Using Purcell's three-link swimmer model, we\nreveal that an odd-elastic filament at low Reynolds number can swim in a\nself-organized manner and that the time-periodic dynamics are characterized by\na stable limit cycle generated by elastohydrodynamic interactions. Also, we\nconsider a noisy shape gait and derive a swimming formula for a general elastic\nmaterial in the Stokes regime with its elasticity modulus being represented by\na non-symmetric matrix, demonstrating that the odd elasticity produces biased\nnet locomotion from random noise."
    },
    {
        "anchor": "Applications of the Peach-Koehler Force in Liquid Crystals: In solids, external stress induces the Peach-Koehler force, which drives\ndislocations to move. Similarly, in liquid crystals, an external angular stress\ncreates an analogous force, which drives disclinations to move. In this work,\nwe develop a method to calculate the relevant angular stress either\nanalytically or numerically, and hence to determine the force on a\ndisclination. We demonstrate this method by applying the Peach-Koehler force\ntheory to four problems: (a) Single disclination in a liquid crystal cell\nbetween two uniform in-plane alignments perpendicular to each other. (b) Array\nof disclinations in a liquid crystal cell with patterned substrates. (c) Pair\nof disclinations in a long capillary tube with homeotropic anchoring. (d)\nRadial hedgehog or disclination loop inside a sphere with homeotropic\nanchoring, and its response to an applied magnetic field. In all of these\nproblems, the Peach-Koehler force theory predicts the equilibrium defect\nstructure, and the predictions are consistent with the results of minimizing\nthe total free energy.",
        "positive": "Sub-diffusion and population dynamics of water confined in soft\n  environments: We have studied by Molecular Dynamics computer simulations the dynamics of\nwater confined in ionic surfactants phases, ranging from well ordered lamellar\nstructures to micelles at low and high water loading, respectively. We have\nanalysed in depth the main dynamical features in terms of mean squared\ndisplacements and intermediate scattering functions, and found clear evidences\nof sub-diffusive behaviour. We have identified water molecules lying at the\ncharged interface with the hydrophobic confining matrix as the main responsible\nfor this unusual feature, and provided a comprehensive picture for dynamics\nbased on a very precise analysis of life times at the interface. We conclude by\nproviding, for the first time to our knowledge, a unique framework for\nrationalising the existence of important dynamical heterogeneities in fluids\nabsorbed in soft confining environments."
    },
    {
        "anchor": "Relating monomer to centre-of-mass distribution functions in polymer\n  solutions: A relationship between the measurable monomer-monomer structure factor, and\nthe centre-of-mass (CM) structure factor of dilute or semi-dilute polymer\nsolutions is derived from Ornstein-Zernike relations within the ``polymer\nreference interaction site model'' (PRISM) formalism, by considering the CM of\neach polymer as an auxiliary site and neglecting direct correlations between\nthe latter and the CM and monomers of neighbouring polymers. The predictions\nagree well with Monte Carlo data for self-avoiding walk polymers, and are\nconsiderably more accurate than the predictions of simple factorization\napproximations.",
        "positive": "Energy transport in jammed sphere packings: We calculate the normal modes of vibration in jammed sphere packings to\nobtain the energy diffusivity, a spectral measure of transport. At the boson\npeak frequency, we find an Ioffe-Regel crossover from a diffusivity that drops\nrapidly with frequency to one that is nearly frequency-independent. This\ncrossover frequency shifts to zero as the system is decompressed towards the\njamming transition, providing unambiguous evidence of a regime in frequency of\nnearly constant diffusivity. Such a regime, postulated to exist in glasses to\nexplain the temperature dependence of the thermal conductivity, therefore\nappears to arise from properties of the jamming transition."
    },
    {
        "anchor": "Local density dependent potential for compressible mesoparticles: We focus on finding a coarse grained description able to reproduce the\nthermodynamic behavior of a molecular system by using mesoparticles\nrepresenting several molecules. Interactions between mesoparticles are modelled\nby an interparticle potential, and an additional internal equation of state is\nused to account for the thermic contribution of coarse grained internal degrees\nof freedom. Moreover, as strong non-equilibrium situations over a wide range of\npressure and density are targeted, the internal compressibility of these\nmesoparticles has to be considered. This is done by introducing a dependence of\nthe potential on the local environment of the mesoparticles, either by defining\na spherical local density or by means of a Voronoi tessellation. As an example,\na local density dependent potential is fitted to reproduce the Hugoniot curve\nof a model of nitromethane, where each mesoparticle represents one thousand\nmolecules.",
        "positive": "Collective dynamics of colloids at fluid interfaces: The evolution of an initially prepared distribution of micron sized colloidal\nparticles, trapped at a fluid interface and under the action of their mutual\ncapillary attraction, is analyzed by using Brownian dynamics simulations. At a\nseparation \\lambda\\ given by the capillary length of typically 1 mm, the\ndistance dependence of this attraction exhibits a crossover from a logarithmic\ndecay, formally analogous to two-dimensional gravity, to an exponential decay.\nWe discuss in detail the adaption of a particle-mesh algorithm, as used in\ncosmological simulations to study structure formation due to gravitational\ncollapse, to the present colloidal problem. These simulations confirm the\npredictions, as far as available, of a mean-field theory developed previously\nfor this problem. The evolution is monitored by quantitative characteristics\nwhich are particularly sensitive to the formation of highly inhomogeneous\nstructures. Upon increasing \\lambda\\ the dynamics show a smooth transition from\nthe spinodal decomposition expected for a simple fluid with short-ranged\nattraction to the self-gravitational collapse scenario."
    },
    {
        "anchor": "Characterization of Geometric Structures of Biaxial Nematic Phases: The ordering matrix, which was originally introduced by de Gennes, is a\nwell-known mathematical device for describing orientational order of biaxial\nnematic liquid crystal. In this paper we propose a new interpretation of the\nordering matrix. We slightly modify the definition of the ordering matrix and\ncall it the geometric order parameter. The geometric order parameter is a\nlinear transformation which transforms a tensorial quantity of an individual\nmolecule to a tensorial quantity observed at a macroscopic scale. The degree of\norder is defined as the singular value of the geometric order parameter. We\nintroduce the anisotropy diagram, which is useful for classification and\ncomparison of various tensorial quantities. As indices for evaluating\nanisotropies of tensorial quantities, we define the degree of anisotropy and\nthe degree of biaxiality. We prove that a simple diagrammatic relation holds\nbetween a microscopic tensor and a macroscopic tensor. We provide a\nprescription to formulate the Landau-de Gennes free energy of a system whose\nconstituent molecules have an arbitrary shape. We apply our prescription to a\nsystem which consists of D_{2h}-symmetric molecules.",
        "positive": "Gradient dynamics description for films of mixtures and suspensions -\n  the case of dewetting triggered by coupled film height and concentration\n  fluctuations: A gradient dynamics model based on an extended interface Hamiltonian is\npresented that is able to describe the dynamics of structuring processes in\nthin films of liquid mixtures, solutions and suspensions on solid substrates\nincluding coupled dewetting and decomposition. After discussing known limiting\ncases the model is employed to investigate the dewetting of thin films of\nliquid mixtures and suspensions under the influence of effective long-range van\nder Waals forces that depend on solute concentration. The occurring fluxes are\ndiscussed and it is shown that spinodal dewetting may be triggered through the\ncoupling of film height and concentration fluctuations. Fully nonlinear\ncalculations provide the time evolution and resulting steady film height and\nconcentration profiles."
    },
    {
        "anchor": "Liquid Crystal Foams: Formation and Coarsening: Coarsening in foams made from the pure liquid crystal, 8CB, has been studied.\nThe foam was made in the nematic phase ($\\textrm{T} = 35 ^{\\circ}\\textrm{C}$)\nby bubbling nitrogen through the pure liquid crystal. The coarsening behavior\nwas investigated at three temperatures; at $\\textrm{T} = 22 ^{\\circ}\\textrm{C}$\nand $33^{\\circ}\\textrm{C}$ in the smectic phase and at $\\textrm{T} =\n34^{\\circ}\\textrm{C}$ in the nematic phase. In smectic and nematic phases the\nmean bubble radius $<R>$ has been measured as a function of time $<R > \\sim\nt^{\\lambda}$. In classical wet soap foams the growth exponent is typically\n$\\lambda \\approx 0.33$ where coarsening is by gas diffusion from bubbles with\nhigh curvature to bubbles with low curvature. In liquid crystal foams a growth\nexponent, $\\lambda = 0.20 \\pm 0.05$ is observed. This may be explained by the\npresence of defects at the surface of the bubbles which slow down the\ncoarsening behaviour. This growth exponent can be observed in both nematic and\nsmectic phases. At higher temperatures typically $>35^{\\circ}\\textrm{C}$\ncoalescence dominates the coarsening behaviour. In the isotropic state,\n$>41.5^{\\circ}\\textrm{C}$, the foam is rapidly unstable.",
        "positive": "Shear recovery and temperature stability of Ca2+ and Ag+ glycolipid\n  fibrillar metallogels with unusual $\u03b2$-sheet-like domains: Low-molecular weight gelators (LMWG) are small molecules (Mw < ~1 kDa), which\nform self-assembled fibrillar networks (SAFiN) hydrogels in water. The great\nmajority of SAFiN gels is described by an entangled network of self-assembled\nfibers, in analogy to a polymer in a good solvent. Here, fibrillation of a\nbiobased glycolipid bolaamphiphile is triggered by Ca2+ or Ag+ ions, added to\nits diluted micellar phase. The resulting SAFiN, which forms hydrogel above 0.5\nwt%, has a ``nano-fishnet'' structure, characterized by a fibrous network of\nboth entangled fibers and $\\beta$-sheets-like rafts, generally observed for\nsilk fibroin, actin hydrogels or mineral imogolite nanotubes, but generally not\nknown for SAFiN. This work focuses on the strength of the SAFIN gels, their\nfast recovery after applying a mechanical stimulus (strain) and their unusual\nresistance to temperature, studied by coupling rheology to small angle X-ray\nscattering (rheo-SAXS) using synchrotron radiation. The Ca2+-based hydrogel\nkeeps its properties up to 55{\\textdegree}C, while the Ag+-based gel shows a\nconstant elastic modulus up to 70{\\textdegree}C, without appearance of any\ngel-to-sol transition temperature. Furthermore, the glycolipid is obtained by\nfermentation from natural resources (glucose, rapeseed oil), thus showing that\nnaturally-engineered compounds can have unprecedented properties, when compared\nto the wide range of chemically derived amphiphiles."
    },
    {
        "anchor": "Turbulent Binary Fluids: A Shell Model Study: We introduce a shell (``GOY'') model for turbulent binary fluids. The\nvariation in the concentration between the two fluids acts as an active scalar\nleading to a redefined conservation law for the energy, which is incorporated\ninto the model together with a conservation law for the scalar. The model is\nstudied numerically at very high values of the Prandtl and Reynolds numbers and\nwe investigate the properties close to the critical point of the miscibility\ngap where the diffusivity vanishes. A peak develops in the spectrum of the\nscalar, showing that a strongly turbulent flow leads to an increase in the\nmixing time. The peak is, however, not very pronounced. The mixing time\ndiverges with the Prandtl number as a power law with an exponent of\napproximately 0.9. The continuum limit of the shell equations leads to a set of\nequations which can be solved by a scaling ansatz, consistent with an exact\nscaling of the Navier-Stokes equations in the inertial range. In this case a\nweak peak also persists for a certain time in the spectrum of the scalar. Exact\nanalytic solutions of the continuous shell equations are derived in the\ninertial range. Starting with fluids at rest, from an initial variation of the\nconcentration difference, one can provoke a ``spontaneous'' generation of a\nvelocity field, analogous to MHD in the early universe.",
        "positive": "Nonequilibrium hyperuniform states in active turbulence: We demonstrate that the complex spatiotemporal structure in active fluids can\nfeature characteristics of hyperuniformity. Using a hydrodynamic model, we show\nthat the transition from hyperuniformity to non-hyperuniformity and\nanti-hyperuniformity depends on the strength of active forcing and can be\nrelated to features of active turbulence without and with scaling\ncharacteristics of inertial turbulence. Combined with identified signatures of\nLevy walks and non-universal diffusion in these systems, this allows for a\nbiological interpretation and the speculation of non-equilibrium hyperuniform\nstates in active fluids as optimal states with respect to robustness and\nstrategies of evasion and foraging."
    },
    {
        "anchor": "Crumpling under an ambient pressure: A pressure chamber is designed to study the crumpling process under an\nambient force. The compression force and its resulting radius for the ball obey\na power law with an exponent that is independent of the thickness and initial\nsize of the sheet. However, the exponent is found to be material-dependent and\nless than the universal value, 0.25, claimed by the previous simulations. The\npower law behavior disappears at high pressure when the compressibility drops\ndiscontinuously, which is suggestive of a jammed state.",
        "positive": "Relations between the diffusion anomaly and cooperative rearranging\n  regions in a hydrophobically nanoconfined water monolayer: We simulate liquid water between hydrophobic walls separated by 0.5 nm, to\nstudy how the diffusion constant D_\\parallel parallel to the walls depends on\nthe microscopic structure of water. At low temperature T, water diffusion can\nbe associated with the number of defects in the hydrogen bonds network.\nHowever, the number of defects solely does not account for the peculiar\ndiffusion of water, with maxima and minima along isotherms. Here, we calculate\na relation that quantitatively reproduces the behavior of D_\\parallel, focusing\non the high-T regime. We clarify how the interplay between breaking of hydrogen\nbonds and cooperative rearranging regions of 1-nm size gives rise to the\ndiffusion extrema, possibly relevant for both bulk and nanoconfined water."
    },
    {
        "anchor": "Axisymmetric Vortices in Spinor Bose-Einstein Condensates under Rotation: The relative stability of various axisymmetric vortices in a spinor\nBose-Einstein condensate with F=1 is examined within extended Bogoliubov\ntheory. This yields the phase diagram in the plane of external rotation\nfrequency vs magnetization. We compare antiferromagnetic, nonmagnetic, and\nferromagnetic cases. The excitation spectrum is evaluated under rotation to\ninvestigate the local stability of the possible vortices and the vortex\nnucleation frequency.",
        "positive": "Investigation of double-gyroid grain boundaries beyond twinning: We study four double-gyroid (DG) grain boundaries (GBs) with different\norientations numerically using the Landau--Brazovskii free energy, including\nthe (422) twin boundary studied recently, a network switching GB, and two tilt\nGBs. Topological variations and geometric deformations are investigated. It is\nfound that deviations in strut lengths and dihedral angles from the bulk DG\nsubstantially exceed changes in strut angles and nodal coplanarity. We also\nexamine the spectra along the contact plane of two grains and utilize them to\nevaluate the GB widths. Of the four GBs we study, the network switching GB\nchanges to the least extent topologically and geometrically, meanwhile has the\nlowest energy and the smallest GB width."
    },
    {
        "anchor": "Thermoresponsive Toughening in LCST-Type Hydrogels: Comparison between\n  Semi-Interpenetrated and Grafted Networks: Hydrophilic and LCST polymer chains, poly(N,N-dimethylacrylamide) (PDMA) and\npoly(Nisopropylacrylamide)(PNIPA), were combined in semi-interpenetrated\narchitectures toinvestigate their responsive properties in swollen isochoric\nconditions comparatively tografted network structures. Using equal weight\nfractions of PDMA and PNIPA, semi-IPNdesigned with opposite topologies have\ndemonstrated a thermoresponsive behavior with verydifferent\nstructure/properties relationships as investigated by calorimetry,\nswellingexperiments, tensile tests and 2D neutron scattering at rest and under\ndeformation. In the caseof the PDMA network interpenetrated by linear PNIPA\nchains, the phase transition of PNIPAgives rise to the formation of large\nmicrodomains, loosely percolating the PDMA network.Above the transition, the\nenhancement of the mechanical properties remains low in terms ofelastic modulus\nand fracture energy. Conversely, the opposite topology, with PDMA\nchainsinterpenetrating the crosslinked PNIPA network, brings a large\nimprovement of themechanical properties at high temperature with a 10-fold\nincrease of the modulus and veryhigh fracture energy. By comparison with\ngrafted hydrogels of similar composition anddifferent topologies, the impact of\nthe primary structure over the phase-separated morphologyand the resulting\nmechanical properties was clearly highlighted.",
        "positive": "Open questions on the impact of an inflated ball: The behaviour of sports balls during impact defines some special features of\neach sport. The velocity of the game, the accuracy of passes or shots, the\ncontrol of the ball direction after impact, the risks of injury, are all set by\nthe impact mechanics of the ball. For inflated sports balls, those\ncharacteristics are finely tuned by the ball inner pressure. As a consequence,\ninflation pressures are regulated for sports played with inflated balls.\nDespite a good understanding of ball elasticity, the source of energy\ndissipation for inflated balls remains controversial. We first give a clear\nview of non-dissipative impact mechanics. Second we review, analyse and\nestimate the different sources of energy dissipation of the multi-physics\nphenomena that occur during the impact. Finally, we propose several experiments\nto decide between gas compression, shell visco-elastic dissipation, solid\nfriction, sound emission or shell vibrations as the major source of energy\ndissipation."
    },
    {
        "anchor": "Local Strain Relaxation Dictates Polymer Melt Viscosity: This paper has been withdrawn due to conflicts with journal copyright issues.",
        "positive": "Molecular dynamics simulation of diisopropyl ether using various\n  interatomic potentials: For diisopropyl ether, a comparative assessment of the accuracy of\ndetermining the density and viscosity is carried out using the method of\nclassical molecular dynamics using three potentials. The accuracy of\ndetermining the viscosity coefficients when using equilibrium and\nnon-equilibrium calculation methods is also investigated."
    },
    {
        "anchor": "Jammed disks of two sizes and weights in a channel: Alternating\n  sequences: Disks of two sizes and weights in alternating sequence are confined to a long\nand narrow channel. The axis of the channel is horizontal and its plane\nvertical. The channel is closed off by pistons that freeze jammed microstates\nout of loose disk configurations subject to moderate pressure, gravity, and\nrandom agitations. Disk sizes and channel width are such that under jamming no\ndisk remains loose and all disks touch one wall. We present exact results for\nthe characterization of jammed macrostates including volume and entropy. The\nrigorous analysis divides the disk sequences of jammed microstates into\noverlapping tiles from which we construct a small number of species of\nstatistically interacting particles. Jammed macrostates depend on dimensionless\ncontrol parameters inferred from ratios between measures of expansion work\nagainst the pistons, gravitational potential energy, and intensity of random\nagitations. These control parameters enter the configurational statistics via\nthe activation energies prior to jamming of the particles. The range of disk\nweights naturally divides into regimes where qualitatively different features\ncome into play. We sketch a path toward generalizations that include random\nsequences under a modified jamming protocol.",
        "positive": "Localized Polymerization Using Single Photon Photoinitiators in\n  Two-photon process for Fabricating Subwavelength Structures: Localized polymerization in subwavelength volumes using two photon dyes has\nnow become a well-established method for fabrication of subwavelength\nstructures. Unfortunately, the two photon absorption dyes used in such process\nare not only expensive but also proprietary. LTPO-L is an inexpensive, easily\navailable single photon photoinitiator and has been used extensively for single\nphoton absorption of UV light for polymerization. These polymerization volumes\nhowever are not localized and extend to micron size resolution having limited\napplications. We have exploited high quantum yield of radicals of LTPO-Lfor\nabsorption of two photons to achieve localized polymerization in subwavelength\nvolumes, much below the diffraction limit. Critical concentration (10wt%) of\nLTPO-Lin acrylate (Sartomer) was found optimal to achieve subwavelength\nlocalized polymerization and has been demonstrated by fabricating 2D/3D complex\nnanostructures and functional devices such as variable polymeric gratings with\nnanoscaled subwavelength resolution. Systematic studies on influence of LTPO-L\nconcentration on two photon polymerization of commercially available\nphotopolymer (Sartomer) show that resolution of the fabricated structures\ncritically depend on loading of LPTO-L. This is expected to unleash the true\npotential of two photon polymerization for fabrication of complex polymeric\nnanodevices at a larger scale."
    },
    {
        "anchor": "Short grafted chains: Monte Carlo simulations of a model for monolayers\n  of amphiphiles: We present Monte Carlo simulations of a coarse-grained model for Langmuir\nmonolayers of amphiphile molecules on a polar substrate. The molecules are\nmodelled as chains of Lennard-Jones beads, with one slightly larger end bead\nconfined in a planar surface. They are simulated in continuous space under\nconditions of constant pressure, using a simulation box of variable size and\nshape. The model exhibits a disordered phase (corresponding to the liquid\nexpanded phase), and various ordered phases (corresponding to the condensed\nphases) with different types of tilt. We calculate the phase diagrams and\ncharacterize the different phases and phase transitions. The effect of varying\nthe chain stiffness is also discussed.",
        "positive": "Frictional state evolution laws and the non-linear nucleation of dynamic\n  shear rupture: We assess if a characteristic length for a non-linear interfacial slip\ninstability follows from theoretical descriptions of sliding friction. We\nexamine friction laws and their coupling with the elasticity of bodies in\ncontact and show that such a length does not always exist. We consider a range\nof descriptions for frictional strength and show that the area needed to\nsupport a slip instability is negligibly small for laws that are more faithful\nto experimental data. This questions whether a minimum earthquake size exists\nand shows that the nucleation phase of dynamic rupture contains discriminatory\ninformation on the nature of frictional strength evolution."
    },
    {
        "anchor": "Anisotropic drop morphologies on corrugated surfaces: The spreading of liquid drops on surfaces corrugated with micron-scale\nparallel grooves is studied both experimentally and numerically. Because of the\nsurface patterning, the typical final drop shape is no longer spherical. The\nelongation direction can be either parallel or perpendicular to the direction\nof the grooves, depending on the initial drop conditions. We interpret this\nresult as a consequence of both the anisotropy of the contact line movement\nover the surface and the difference in the motion of the advancing and receding\ncontact lines. Parallel to the grooves, we find little hysteresis due to the\nsurface patterning and that the average contact angle approximately conforms to\nWenzel's law as long as the drop radius is much larger than the typical length\nscale of the grooves. Perpendicular to the grooves, the contact line can be\npinned at the edges of the ridges leading to large contact angle hysteresis.",
        "positive": "Non-Euclidean Origami: Traditional origami starts from flat surfaces, leading to crease patterns\nconsisting of Euclidean vertices. However, Euclidean vertices are limited in\ntheir folding motions, are degenerate, and suffer from misfolding. Here we show\nhow non-Euclidean 4-vertices overcome these limitations by lifting this\ndegeneracy, and that when the elasticity of the hinges is taken into account,\nnon-Euclidean 4-vertices permit higher-order multistability. We harness these\nadvantages to design an origami inverter that does not suffer from misfolding\nand to physically realize a tristable vertex."
    },
    {
        "anchor": "Stability and dewetting of thin liquid films: The stability of thin liquid coatings is of fundamental interest in every-\nday life. Homogeneous and non-volatile liquid coatings may dewet either by\nheterogeneous nucleation, thermal nucleation, or spinodal dewetting. Wetting\nand dewetting is explained on a fundamental level, including a discussion of\nrelevant interactions. The article will also address the various dewetting\nscenarios and explain how the effective interface potential governs the\nbehavior obtained for various stratified substrates and film thicknesses.",
        "positive": "Granular clustering in a hydrodynamic simulation: We present a numerical simulation of a granular material using hydrodynamic\nequations. We show that, in the absence of external forces, such a system\nphase-separates into high density and low density regions. We show that this\nseparation is dependent on the inelasticity of collisions, and comment on the\nmechanism for this clustering behavior. Our results are compatible with the\ngranular clustering seen in experiments and molecular dynamic simulations of\ninelastic hard disks."
    },
    {
        "anchor": "The evaporation of concentrated polymer solutions is insensitive to\n  relative humidity: A recent theory suggests that the evaporation kinetics of macromolecular\nsolutions is insensitive to the ambient relative humidity (RH) due to the\nformation of a `polarisation layer' of solutes at the air-solution interface.\nWe confirm this insensitivity up to RH~80% in the evaporation of polyvinyl\nalcohol solutions from open-ended capillaries. To explain the observed drop in\nevaporation rate at higher RH, we need to invoke compressive stresses due to\ninterfacial polymer gelation. Moreover, RH-insensitive evaporation sets in\nearlier than theory predicts, suggesting a further role for a gelled `skin'. We\ndiscuss the relevance of these observations for respiratory virus transmission\nvia aerosols.",
        "positive": "Mapping vesicle shapes into the phase diagram: A comparison of\n  experiment and theory: Phase-contrast microscopy is used to monitor the shapes of micron-scale\nfluid-phase phospholipid-bilayer vesicles in aqueous solution. At fixed\ntemperature, each vesicle undergoes thermal shape fluctuations. We are able\nexperimentally to characterize the thermal shape ensemble by digitizing the\nvesicle outline in real time and storing the time-sequence of images. Analysis\nof this ensemble using the area-difference-elasticity (ADE) model of vesicle\nshapes allows us to associate (map) each time-sequence to a point in the\nzero-temperature (shape) phase diagram. Changing the laboratory temperature\nmodifies the control parameters (area, volume, etc.) of each vesicle, so it\nsweeps out a trajectory across the theoretical phase diagram. It is a\nnontrivial test of the ADE model to check that these trajectories remain\nconfined to regions of the phase diagram where the corresponding shapes are\nlocally stable. In particular, we study the thermal trajectories of three\nprolate vesicles which, upon heating, experienced a mechanical instability\nleading to budding. We verify that the position of the observed instability and\nthe geometry of the budded shape are in reasonable accord with the theoretical\npredictions. The inability of previous experiments to detect the ``hidden''\ncontrol parameters (relaxed area difference and spontaneous curvature) make\nthis the first direct quantitative confrontation between vesicle-shape theory\nand experiment."
    },
    {
        "anchor": "Continuum theory of electrostatic-elastic coupling interactions in\n  colloidal crystals: Electrostatic-elastic coupling in colloidal crystals, composed of a mobile\nCoulomb gas permeating a fixed background crystalline lattice of charged\ncolloids, is studied on the continuum level in order to analyze the\nlattice-mediated interactions between mobile charges. The linearized, Debye-H\\\"\nuckel-like mean-field equations allow for an analytic solution incorporating\nthe minimal coupling between electrostatic and displacement fields leading to\nan additional effective attractive interaction between mobile charges. For\nsmall screening lengths, the interactions between mobile like charges exhibit a\ncoupling-strength-dependent behavior, with lattice mediated effective\ninteraction ranging from weak to strong attraction, while for large screening\nlengths the lattice mediated interaction remains purely attractive. By\nanalyzing Gaussian fluctuations around the mean-field solution we identify its\nregion of stability in terms of the electrostatic-elastic screening length. A\ndetailed continuum theory incorporating the standard lattice elasticity and\nelectrostatics of mobile charges augmented by the electrostatic-elastic\ncoupling terms can serve as a baseline for more detailed microscopic models.",
        "positive": "Thermodynamics of Protein Folding from Coarse-Grained Models'\n  Perspectives: Folding and aggregation of proteins, the interaction between proteins and\nmembranes, as well as the adsorption of organic soft matter to inorganic solid\nsubstrates belong to the most interesting challenges in understanding structure\nand function of complex macromolecules. This is reasoned by the\ninterdisciplinary character of the associated questions ranging from the\nmolecular origin of the loss of biological functionality as, for example, in\nAlzheimer's disease to the development of organic circuits for biosensory\napplications. In this lecture, we focus on the analysis of mesoscopic models\nfor protein folding, aggregation, and hybrid systems of soft and solid\ncondensed matter. The simplicity of the coarse-grained models allows for a more\nuniversal description of the notoriously difficult problem of protein folding.\nIn this approach, classifications of structure formation processes with respect\nto the conformational pseudophases are possible. This is similar in aggregation\nand adsorption processes, where the individual folding propensity is influenced\nby external forces. The main problem in studies of conformational transitions\nis that the sequences of amino acids proteins are built up of are necessarily\nof finite length and, therefore, a thermodynamic limit does not exist. Thus,\nstructural transitions are not phase transitions in the strict thermodynamic\nsense and the analysis of pseudouniversal aspects is intricate, as apparently\nsmall-system effects accompany all conformational transitions and cannot be\nneglected."
    },
    {
        "anchor": "Bistable colloidal orientation in polar liquid near a charged wall: We examine the translation and rotation of an uncharged spheroidal colloid in\npolar solvents (water) near a charged flat surface. We solve the nonlinear\nPoisson-Boltzmann equation outside of the colloid in two dimensions for all\ntilt angles $\\theta$ with respect to the surface normal. The colloid's size is\nassumed to be comparable to the Debye's length and hence field gradients are\nessential. The Maxwell stress tensor, including the ideal gas pressure of ions,\nis integrated over the colloid's surface to give the total force and torque on\nthe colloid. From the torque we calculate the effective angular potential\n$U_{\\rm eff}(\\theta)$. The classical behavior where the colloid tends to align\nin the direction perpendicular to the surface (parallel to the field,\n$\\theta=0$) is retrieved at large colloid-surface distances or small surface\npotentials. We find a surprising transition whereby at small separations or\nlarge potentials the colloid aligns parallel to the surface\n($\\theta=90^\\circ$). Moreover, this colloid orientation is amplified at a\nfinite value of the aspect ratio. This transition may have important\nconsequences to flow of colloidal suspensions or as a tool to switch layering\nof such suspensions near a surface.",
        "positive": "On the Abaqus FEA model of finite viscoelasticity: Predictions of the QLV (Quasi-Linear Viscoelastic) constitutive law are\ncompared with those of the ABAQUS viscoelastic model for two simple motions in\norder to highlight, in particular, their very different dissipation rates and\ncertain shortcomings of the ABAQUS model."
    },
    {
        "anchor": "The magnonic superfluid droplet at room temperature: We declare the observation of spin superfluid state in Yttrium Iron Garnet\n(YIG) at room temperature. It is similar to a Homogeneous Precessing State\n(HPD), observed earlier in antiferromagnetic superfluid $^3$He-B. The formation\nof this state explains by the repulsive interaction between magnons, which is\nrequired as a prior condition for the spin superfluidity. It establishes an\nenergy gap, which stabilizes the long range superfluid transport of\nmagnetization and determines the Ginzburg-Landau coherence length. This\ndiscovery paves a way to many quantum applications of supermagnonics at room\ntemperature, such as magnetic Josephson effect, long distance spin transport,\nQ-bit, quantum logics, magnetic sensors and others.",
        "positive": "The Primitive Model in Classical Density Functional Theory: Beyond the\n  Standard Mean-Field Approximation: The primitive model describes ions by point charges with an additional\nhard-core interaction. In classical density-functional theory the mean-field\nelectrostatic contribution can be obtained from the first order of a functional\nperturbation of the pair potential for an uncharged reference system of hard\nspheres. This mean-field electrostatic term particularly contributes at\nparticle separations that are forbidden due to hard-core overlap. In this work\nwe modify the mean-field contribution such that the pair potential is constant\nfor distances smaller than the contact distance of the ions. We motivate our\nmodification by the underlying splitting of the potential, which is similar to\nthe splitting of the Weeks-Chandler-Andersen potential and leads to\nhigher-order terms in the respective expansion of the functional around the\nreference system. The resulting formalism involves weighted densities similar\nto the ones found in fundamental measure theory. To test our modifications, we\nanalyze and compare density profiles, direct and total correlation functions,\nand the thermodynamic consistency of the functional via a widely established\nsum rule and the virial pressure formula for our modified functional, for\nestablished functionals, and for data from computer simulations. We found that\nour modifications clearly show improvements compared to the standard mean-field\nfunctional, especially when predicting layering effects and direct correlation\nfunctions in high concentration scenarios; for the latter we also find improved\nconsistency when calculated via different thermodynamic routes. In conclusion,\nwe demonstrate how modifications towards higher order corrections beyond\nmean-field functionals can be made and how they perform, by this providing a\nbasis for systematic future improvements in classical density-functional theory\nfor the description of electrostatic interactions."
    },
    {
        "anchor": "Free energy and segregation dynamics of two channel-confined polymers of\n  different length: Polymers confined to a narrow channel are subject to strong entropic forces\nthat tend to drive the molecules apart. In this study, we use Monte Carlo\ncomputer simulations to study the segregation behavior of two flexible\nhard-sphere polymers under confinement in a cylindrical channel. We focus on\nthe effects of using polymers of different lengths. We measure the variation of\nthe conformational free energy, $F$, with the center-of-mass separation\ndistance, $\\lambda$. The simulations reveal four different separation regimes,\ncharacterized by different scaling properties of the free energy with respect\nto the polymer lengths and the channel diameter, $D$. We propose a regime map\nin which the state of the system is determined by the values of the quantities\n$N_2/N_1$ and $\\lambda/(N_1+N_2)D^{-\\beta}$, where $N_1$ and $N_2$ are the\npolymer lengths, and where $\\beta\\approx 0.64$. The observed scaling behavior\nof $F(\\lambda)$ in each regime is in reasonable agreement with predictions\nusing a simple theoretical model. In addition, we use MC dynamics simulations\nto study the segregation dynamics of initially overlapping polymers by\nmeasurement of the incremental mean first-passage time with respect to\n$\\lambda$. For systems characterized by a wide range of $\\lambda$ in which a\nshort polymer is nested within a longer one, the segregation dynamics are close\nto that expected for two noninteracting 1D random walkers undergoing unbiased\ndiffusion. When the free energy gradient is large segregation is rapid and\ncharacterized by out-of-equilibrium effects.",
        "positive": "Monte Carlo simulations of biaxial molecules near a hard wall: A system of optimal biaxial molecules placed at the sites of a cubic lattice\nis studied in an extended Lebwohl-Lasher model. Molecules interact only with\ntheir nearest neighbors through the pair potential that depends on the molecule\norientations. It is known that in the homogeneous system there is a direct\nsecond-order transition from the isotropic to the biaxial nematic phase, but\nproperties of confined systems are less known. In the present paper the lattice\nhas periodic boundary conditions in the X and Y directions and it has two walls\nwith planar anchoring, perpendicular to the Z direction. We have investigated\nthe model using Monte Carlo simulations on $N_x \\times N_y \\times N_z$\nlattices, $N_x = N_y = 10, 16$, $N_z$ from 3 to 19, with and without assuming\nmirror symmetry. This study is complementary to the statistical description of\nhard spheroplatelets near a hard wall by Kapanowski and Abram [Phys. Rev. E 89,\n062503 (2014)]. The temperature dependence of the order-parameter profiles\nbetween walls is calculated for many wall separations. For large wall\nseparations there are the surface layers with biaxial ordering at both walls\n(4-5 lattice constants wide) and beyond the surface layers the order parameters\nhave values as in the homogeneous system. For small wall separations the\nisotropic-biaxial transition is shifted and the surface layers are thinner.\nAbove the isotropic-biaxial transition the preferable orientations in both\nsurface layers can be different. It is interesting that planar anchoring for\nbiaxial molecules leads to the uniaxial interactions at the wall. As a result\nwe get the planar Lebwohl-Lasher model with additional (biaxial) interactions\nwith the neighbors from the second layer, where the Kosterlitz-Thouless\ntransition is present."
    },
    {
        "anchor": "On the Prony Series Representation of Stretched Exponential Relaxation: Stretched exponential relaxation is a ubiquitous feature of homogeneous\nglasses. The stretched exponential decay function can be derived from the\ndiffusion-trap model, which predicts certain critical values of the fractional\nstretching exponent. In practical implementations of glass relaxation models,\nit is computationally convenient to represent the stretched exponential\nfunction as a Prony series of simple exponentials. Here, we perform a\ncomprehensive mathematical analysis of the Prony series approximation of the\nstretched exponential relaxation, including optimized coefficients for certain\ncritical values of the exponent. The fitting quality of the Prony series is\nanalyzed as a function of the number of terms in the series. With a sufficient\nnumber of terms, the Prony series can accurately capture the time evolution of\nthe stretched exponential function, including its \"fat tail\" at long times.\nHowever, it is unable to capture the divergence of the first-derivative of the\nstretched exponential function in the limit of zero time. We also present a\nfrequency-domain analysis of the Prony series representation of the stretched\nexponential function and discuss its physical implications for the modeling of\nglass relaxation behavior.",
        "positive": "Depletion-induced crystallization of anisotropic triblock colloids: The intricate interplay between colloidal particle shape and precisely\nengineered interaction potentials has paved the way for the discovery of\nunprecedented crystal structures in both two and three dimensions. Here, we\nmake use of anisotropic triblock colloidal particles composed of two distinct\nmaterials. The resulting surface charge heterogeneity can be exploited to\ngenerate regioselective depletion interactions and directional bonding. Using\nextensive molecular dynamics simulations and a dimensionality reduction\nanalysis approach, we map out state diagrams for the self-assembly of such\ncolloids as a function of their aspect ratio and packing fraction for varying\ndepletant sizes in a quasi two-dimensional set-up. We observe the formation of\na wide variety of crystal structures such as a herringbone, brick-wall, tilted\nbrick-wall, and (tilted) ladder-like structures. More specifically, we\ndetermine the optimal parameters to enhance crystallization, and investigate\nthe nucleation process. Additionally, we explore the potential of using crystal\nmonolayers as templates for deposition, thereby creating complex\nthree-dimensional structures that hold promise for future applications."
    },
    {
        "anchor": "Pre-transition effects mediate forces of assembly between transmembrane\n  proteins: We present a mechanism for a generic and powerful force of assembly and\nmobility for transmembrane proteins in lipid bilayers. This force is a\npre-transition (or pre-melting) effect for the first-order transition between\nordered and disordered phases in the host membrane. Using large scale molecular\nsimulation, we show that a protein with hydrophobic thickness equal to that of\nthe disordered phase embedded in an ordered bilayer stabilizes a microscopic\norder-disorder interface, and the stiffness of that interface is finite. When\ntwo such proteins approach each other, they assemble because assembly reduces\nthe net interfacial free energy. In analogy with the hydrophobic effect, we\nrefer to this phenomenon as the \"orderphobic effect\". The effect is mediated by\nproximity to the order-disorder phase transition and the size and hydrophobic\nmismatch of the protein. The strength and range of forces arising from the\norderphobic effect are significantly larger than those that could arise from\nmembrane elasticity for the membranes we examine.",
        "positive": "Qualitative change in structural dynamics of some glass-forming systems: Analysis of temperature dependence of structural relaxation time in\nsupercooled liquids revealed a qualitatively distinct feature - a sharp,\ncusp-like maxumum in the second derivative of its logarithm. It suggests that\nthe super-Arrhenius behavior of the structural relaxation time in glass-forming\nliquids eventually crosses over to the Arrhenius behavior below the temperature\nof maximum, and there is no divergence of the relaxation time at non-zero\ntemperature. The position of the maximum can be both above or below glass\ntransition temperature, depending on the sensitivity of the structural\nrelaxation time to changes in density. These results might turn the discussion\nof the glass transition to the new avenue - the origin of the limiting\nactivation energy for structural relaxation at low temperatures."
    },
    {
        "anchor": "Colloidal gelation and non-ergodicity transitions: Within the framework of the mode coupling theory (MCT) of structural\nrelaxation, mechanisms and properties of non-ergodicity transitions in rather\ndilute suspensions of colloidal particles characterized by strong short-ranged\nattractions are studied. Results building on the virial expansion for particles\nwith hard cores and interacting via an attractive square well potential are\npresented, and their relevance to colloidal gelation is discussed.",
        "positive": "Simultaneous polydirectional transport of colloidal bipeds: Detailed control over the motion of colloidal particles is relevant in many\napplications in colloidal science such as lab-on-a-chip devices. Here, we use\nan external magnetic field to assemble paramagnetic colloidal spheres into\ncolloidal rods of several lengths. The rods reside above a square magnetic\npattern and are transported via modulation of the direction of the external\nmagnetic field. The rods behave like bipeds walking above the pattern.\nDepending on their length, the bipeds perform topologically distinct classes of\nprotected walks above the pattern. We demonstrate that it is possible to design\nparallel polydirectional modulation loops of the external field that command up\nto six classes of bipeds to walk on distinct predesigned paths. We use such\nparallel polydirectional loops to induce the collision of reactant bipeds,\ntheir polymerization addition reaction to larger bipeds, the separation of\nproduct bipeds from the educts, the sorting of different product bipeds, and\nalso the parallel writing of a word consisting of several different letters."
    },
    {
        "anchor": "Stability of casein micelles cross-linked with genipin: a\n  physicochemical study as a function of pH: Chemical or enzymatic cross-linking of casein micelles (CMs) increases their\nstability against dissociating agents. In this paper, a comparative study of\nstability between native CMs and CMs cross-linked with genipin (CMs-GP) as a\nfunction of pH is described. Stability to temperature and ethanol were\ninvestigated in the pH range 2.0-7.0. The size and the charge\n($\\zeta$-potential) of the particles were determined by dynamic light\nscattering. Native CMs precipitated below pH 5.5, CMs-GP precipitated from pH\n3.5 to 4.5, whereas no precipitation was observed at pH 2.0-3.0 or pH 4.5-7.0.\nThe isoelectric point of CMs-GP was determined to be pH 3.7. Highest stability\nagainst heat and ethanol was observed for CMs-GP at pH 2, where visible\ncoagulation was determined only after 800 s at 140 $^\\circ$C or 87.5% (v/v) of\nethanol. These results confirmed the hypothesis that cross-linking by GP\nincreased the stability of CMs.",
        "positive": "Decoupling of dipolar and hydrophobic motions in biological membranes: Cells use homeostatic mechanisms to maintain an optimal composition of\ndistinct types of phospholipids in cellular membranes. The hydrophilic dipolar\nlayer at the membrane interface, composed of phospholipid headgroups, regulates\nthe interactions between cell membranes and incoming molecules, nanoparticles,\nand viruses. On the other hand, the membrane hydrophobic core determines\nmembrane thickness and forms an environment for membrane-bound molecules such\nas transmembrane proteins. A fundamental open question is to what extent the\nmotions of these regions are coupled and, consequently, how strongly the\ninteractions of lipid headgroups with other molecules depend on the properties\nand composition of the membrane hydrophobic core. We combine advanced\nsolid-state nuclear magnetic resonance spectroscopy methodology with\nhigh-fidelity molecular dynamics simulations to demonstrate how the rotational\ndynamics of choline headgroups remain nearly unchanged (slightly faster) with\nincorporation of cholesterol into a phospholipid membrane, contrasting the well\nknown extreme slowdown of the other phospholipid segments. Notably, our results\nsuggest a new paradigm where phospholipid headgroups interact as quasi-freely\nrotating flexible dipoles at the interface, independent of the properties in\nthe hydrophobic region."
    },
    {
        "anchor": "Uncovering novel phase transitions in dense dry polar active fluids\n  using a lattice Boltzmann method: The dynamics of dry active matter have implications for a diverse collection\nof biological phenomena spanning a range of length and time scales, such as\nanimal flocking, cell tissue dynamics, and swarming of inserts and bacteria.\nUniting these systems are a common set of symmetries and conservation laws,\ndefining dry active fluids as a class of physical system. Many interesting\nbehaviours have been observed at high densities, which remain difficult to\nsimulate due to the computational demand. Here, we show how two-dimensional dry\nactive fluids in a dense regime can be studied using a simple modification of\nthe lattice Boltzmann method. We apply our method on a model that exhibits\nmotility-induced phase separation, and an active model with contact inhibition\nof locomotion, which has relevance to collective cell migration. For the\nlatter, we uncover multiple novel phase transitions: two first-order and one\npotentially critical. We further support our simulation results with an\nanalytical treatment of the hydrodynamic equations obtained via a\nChapman-Enskog coarse-graining procedure.",
        "positive": "Complex microwave conductivity of Na-DNA powders: We report the complex microwave conductivity, $\\sigma=\\sigma_1-i\\sigma_2$, of\nNa-DNA powders, which was measured from 80 K to 300 K by using a microwave\ncavity perturbation technique. We found that the magnitude of $\\sigma_1$ near\nroom temperature was much larger than the contribution of the surrounding water\nmolecules, and that the decrease of $\\sigma_1$ with decreasing temperature was\nsufficiently stronger than that of the conduction of counterions. These results\nclearly suggest that the electrical conduction of Na-DNA is intrinsically\nsemiconductive."
    },
    {
        "anchor": "Self Assembly of Soft Matter Quasicrystals and Their Approximants: The surprising recent discoveries of quasicrystals and their approximants in\nsoft matter systems poses the intriguing possibility that these structures can\nbe realized in a broad range of nano- and micro-scale assemblies. It has been\ntheorized that soft matter quasicrystals and approximants are largely\nentropically stabilized, but the thermodynamic mechanism underlying their\nformation remains elusive. Here, we use computer simulation and free energy\ncalculations to demonstrate a simple design heuristic for assembling\nquasicrystals and approximants in soft matter systems. Our study builds on\nprevious simulation studies of the self-assembly of dodecagonal quasicrystals\nand approximants in minimal systems of spherical particles with complex,\nhighly-specific interaction potentials. We demonstrate an alternative\nentropy-based approach for assembling dodecagonal quasicrystals and\napproximants based solely on particle functionalization and shape, thereby\nrecasting the interaction-potential-based assembly strategy in terms of\nsimpler-to-achieve bonded and excluded-volume interactions. Here, spherical\nbuilding blocks are functionalized with mobile surface entities to encourage\nthe formation of structures with low surface contact area, including\nnon-close-packed and polytetrahedral structures. The building blocks also\npossess shape polydispersity, where a subset of the building blocks deviate\nfrom the ideal spherical shape, discouraging the formation of close-packed\ncrystals. We show that three different model systems with both of these\nfeatures -- mobile surface entities and shape polydispersity -- consistently\nassemble quasicrystals and/or approximants. We argue that this design strategy\ncan be widely exploited to assemble quasicrystals and approximants on the nano-\nand micro- scales. In addition, our results further elucidate the formation of\nsoft matter quasicrystals in experiment.",
        "positive": "Dynamics of a self-propelled particle in a harmonic trap: The dynamics of an active walker in a harmonic potential is studied\nexperimentally, numerically and theoretically. At odds with usual models of\nself-propelled particles, we identify two dynamical states for which the\nparticle condensates at finite distance from the trap center. In the first\nstate, also found in other systems, the particle points radially outward the\ntrap, while diffusing along the azimuthal direction. In the second state, the\nparticle performs circular orbits around the center of the trap. We show that\nself-alignment, taking the form of a torque coupling the particle orientation\nand velocity, is responsible for the emergence of this second dynamical state.\nThe transition between the two states is controlled by the persistence of the\nparticle orientation. At low inertia, the transition is continuous. For large\ninertia the transition is discontinuous and a coexistence regime with\nintermittent dynamics develops. The two states survive in the over-damped limit\nor when the particle is confined by a curved hard wall."
    },
    {
        "anchor": "Self-organization in suspensions of end-functionalized semiflexible\n  polymers under shear flow: The nonequilibrium dynamical behavior and structure formation of\nend-functionalized semiflexible polymer suspensions under flow are investigated\nby mesoscale hydrodynamic simulations. The hybrid simulation approach combines\nthe multiparticle collision dynamics method for the fluid, which accounts for\nhydrodynamic interactions, with molecular dynamics simulations for the\nsemiflexible polymers. In equilibrium, various kinds of scaffold-like network\nstructures are observed, depending on polymer flexibility and end-attraction\nstrength. We investigate the flow behavior of the polymer networks under shear\nand analyze their nonequilibrium structural and rheological properties. The\nscaffold structure breaks up and densified aggregates are formed at low shear\nrates, while the structural integrity is completely lost at high shear rates.\nWe provide a detailed analysis of the shear-rate-dependent flow-induced\nstructures. The studies provide a deeper understanding of the formation and\ndeformation of network structures in complex materials.",
        "positive": "Theory of Polymer Chains in Poor Solvent: Single-Chain Structure,\n  Solution Thermodynamics and Theta Point: Using the language of the Flory chi parameter, we develop a theory that\nunifies the treatment of the single-chain structure and the solution\nthermodynamics of polymers in poor solvents. The structure of a globule and its\nmelting thermodynamics is examined using the self-consistent filed theory. Our\nresults show that the chain conformation involves three states prior to the\nglobule-to-coil transition: the fully-collapsed globule, the swollen globule\nand the molten globule, which are distinguished by the core density and the\ninterfacial thickness. By examining the chain-length dependence of the melting\nof the swollen globule, we find universal scaling behavior in the chain\nproperties near the Theta point. The information of density profile and free\nenergy of the globule is used in the dilute solution thermodynamics to study\nthe phase equilibrium of polymer solution. Our results show different scaling\nbehavior of the solubility of polymers in the dilute solution compared to the\nF-H theory, both in the chi dependence and the chain-length dependence. From\nthe perspectives of single chain structure and solution thermodynamics, our\nresults verifies the consistency of the Theta point defined by different\ncriteria in the limit of infinite chain length: the disappearance of the second\nviral coefficient, the abrupt change in chain size and the critical point in\nthe phase diagram of the polymer solution. Our results show the value of chi at\nthe Theta point is 0.5 (for the case of equal monomer and solvent volume),\nwhich coincides with the value predicted from the F-H theory."
    },
    {
        "anchor": "Enhanced oil removal from water in oil stable emulsions using\n  electrospun nanocomposite fiber mats: Fibrous mats with hydrophobic and oleophilic properties have been fabricated\nand used as absorbents of oil from stable water in oil emulsions.",
        "positive": "Effects of fluctuations on correlation functions in inhomogeneous\n  mixtures: Approximate expressions for correlation functions in binary inhomogeneous\nmixtures are derived in a framework of the mesoscopic theory [Ciach A., Mol.\nPhys., 2011, {\\textbf{109}}, 1101]. Fluctuation contribution is taken into\naccount in a Brazovskii-type approximation. Explicit results are obtained for\ntwo model systems. In the two models, the diameters of the hard cores of\nparticles are equal, and the interactions favour a periodic arrangement of\nalternating species A and B. However, the optimal distance between the species\nA and B is much different in the two models. Theoretical results for different\ntemperature and volume fractions of the two components are compared with the\nresults of Monte Carlo simulations, and the structure is illustrated by\nsimulation snapshots. Despite different interaction potentials and different\nlength scale of the local ordering, properties of the correlation functions in\nthe two models are very similar."
    },
    {
        "anchor": "Self-Assembly and Nonlinear Dynamics of Dimeric Colloidal Rotors in\n  Cholesterics: We study by simulation the physics of two colloidal particles in a\ncholesteric liquid crystal with tangential order parameter alignment at the\nparticle surface. The effective force between the pair is attractive at short\nrange and favors assembly of colloid dimers at specific orientations relative\nto the local director field. When pulled through the fluid by a constant force\nalong the helical axis, we find that such a dimer rotates, either continuously\nor stepwise with phase-slip events. These cases are separated by a sharp\ndynamical transition and lead, respectively, to a constant or an\never-increasing phase lag between the dimer orientation and the local nematic\ndirector.",
        "positive": "Impact of Short- and Long-range Forces on Protein Conformation and\n  Adsorption Kinetics: We have studied the adsorption kinetics of the protein amylase at\nsolid/liquid interfaces. Offering substrates with tailored properties, we are\nable to separate the impact of short- and long-range interactions. By means of\na colloidal Monte Carlo approach including conformational changes of the\nadsorbed proteins induced by density fluctuations, we develop a scenario that\nis consistent with the experimentally observed three-step kinetics on specific\nsubstrates. Our observations show that not only the surface chemistry\ndetermines the properties of an adsorbed protein layer but also the van der\nWaals contributions of a composite substrate may lead to non-negligible\neffects."
    },
    {
        "anchor": "A Bhatnagar-Gross-Krook-like Model Kinetic Equation for a Granular Gas\n  of Inelastic Rough Hard Spheres: The Boltzmann collision operator for a dilute granular gas of inelastic rough\nhard spheres is much more intricate than its counterpart for inelastic smooth\nspheres. Now the one-body distribution function depends not only on the\ntranslational velocity of the center of mass but also on the angular velocity\nof the particle. Moreover, the collision rules couple both velocities,\ninvolving not only the coefficient of normal restitution but also the\ncoefficient of tangential restitution. The aim of this paper is to propose an\nextension to inelastic rough particles of a Bhatnagar-Gross-Krook-like kinetic\nmodel previously proposed for inelastic smooth particles. The Boltzmann\ncollision operator is replaced by the sum of three terms representing: (i) the\nrelaxation to a two-temperature local equilibrium distribution, (ii) the action\nof a nonconservative drag force proportional to the peculiar velocity, and\n(iii) the action of a nonconservative torque equal to a linear combination of\nthe angular velocity and its mean value. The three coefficients in the force\nand torque are fixed to reproduce the Boltzmann collisional rates of change of\nthe mean angular velocity and of the two granular temperatures (translational\nand rotational). A simpler version of the model is also constructed in the form\nof two coupled kinetic equations for the translational and rotational velocity\ndistributions. The kinetic model is applied to the simple shear flow steady\nstate and the combined influence of the two coefficients of restitution on the\nshear and normal stresses and on the translational velocity distribution\nfunction is analyzed.",
        "positive": "Mixing-Demixing Phase Diagram for Simple Liquids in Non-Uniform Electric\n  Fields: We deduce the mixing-demixing phase diagram for binary liquid mixtures in an\nelectric field for various electrode geometries and arbitrary constitutive\nrelation for the dielectric constant. By focusing on the behavior of the\nliquid-liquid interface, we produce simple analytic expressions for the\ndependence of the interface location on experimental parameters. We also show\nthat the phase diagram contains regions where liquid separation cannot occur\nunder any applied field. The analytic expression for the boundary\n\"electrostatic binodal\" line reveals that the regions' size and shape depend\nstrongly on the dielectric relation between the liquids. Moreover, we predict\nthe existence of an \"electrostatic spinodal\" line that identifies conditions\nwhere the liquids are in a metastable state. We finally construct the phase\ndiagram for closed systems by mapping solutions onto those of an open system\nvia an effective liquid composition. For closed systems at a fixed temperature\nand mixture composition, liquid separation occurs in a finite \"window\" of\nsurface potential (or charge density). Larger potentials or charge densities\ncounterintuitively destroy the interface, leading to liquid mixing. These\nresults give valuable guides for experiments by providing easily testable\npredictions for how liquids behave in non-uniform electric fields."
    },
    {
        "anchor": "Wrinkles and folds in a fluid-supported sheet of finite size: A laterally confined thin elastic sheet lying on a liquid substrate displays\nregular undulations, called wrinkles, characterized by a spatially extended\nenergy distribution and a well-defined wavelength $\\lambda$. As the confinement\nincreases, the deformation energy is progressively localized into a single\nnarrow fold. An exact solution for the deformation of an infinite sheet was\npreviously found, indicating that wrinkles in an infinite sheet are unstable\nagainst localization for arbitrarily small confinement. We present an extension\nof the theory to sheets of finite length $L$, accounting for the experimentally\nobserved wrinkle-to-fold transition. We derive an exact solution for the\nperiodic deformation in the wrinkled state, and an approximate solution for the\nlocalized, folded state. We show that a second-order transition between these\ntwo states occurs at a critical confinement $\\Delta_F=\\lambda^2/L$.",
        "positive": "Percolation of particles on recursive lattices: (I) a new theoretical\n  approach: Powdered materials of sizes ranging from nanometers to microns are widely\nused in materials science and are carefully selected to enhance the performance\nof a matrix. Fillers have been used in order to improve, among the others,\nmechanical, rheological, electrical, magnetic and thermal properties of the\nhost material. Changes in the shape and size of the filler particles are known\nto affect and, in some cases, magnify such enhancement. This effect is usually\nassociated with an increased probability of formation of a percolating cluster\nof filler particles in the matrix. Previous model calculations of percolation\nin polymeric systems generally did not take the possible difference between the\nsize and shape of monomers and filler particles into account and usually\nneglected interactions or accounted for them in a crude fashion. In our\napproach the original lattice is replaced by a recursive structure on which\ncalculations are done exactly and interactions as well as size and shape\ndisparities can be easily taken into account. Here we introduce the recursive\napproach, we describe how to derive the percolation threshold as a function of\nthe various parameters of the problem and we apply the new approach to the\nanalysis of the effect of correlations among monodisperse particles on the\npercolation threshold of a system. Then in the second paper of the series we\ntackle the issue of the effect of size and shape disparities of the particles\non their percolation properties while in the last part we describe the effect\nof the presence of a polymer matrix."
    },
    {
        "anchor": "Self-assembly in rod/coil block copolymers: Degenerate behavior under\n  nonconfinement: The self-assembly of block copolymers containing rigid blocks have received\nabiding attention due to its rich phase behavior and potential for use in a\nvariety of applications. In this work, under asymmetric interactions between\nrod/coil components, the self-assembly of coil/coil/rod ABC triblock copolymers\nis studied using self-consistent field of lattice model. In addition to\nmicelles, centrosymmetric lamellae (CSLM), lamellae, perforated lamellae,\nstrips and gyroids, non-centrosymmetric (NCSLM) lamellae and wavy morphologies\nare observed as stable phases. The phase diagram of interaction between rod and\ncoil components versus the rod fraction is constructed given a fixed\ninteraction between coil components. For intermediate rod fraction, degenerate\nbehavior is observed. NCSLM and CSLM are degenerate structures. It is found\nthat the entropy of chain conformation plays an important role for this rich\nbehavior. A mechanism of the degenerate behavior is proposed in coil/rod block\ncopolymers under noncofinement. This study provides some new insights into the\ndegenerate behavior of block compolymers, which can offer a theoretical\nreference for related experiments.",
        "positive": "Routes to gelation in a clay suspension: The gelation of water suspension of a synthetic clay (Laponite) has been\nstudied by dynamic light scattering in a wide range of clay weight\nconcentration (Cw = 0.003-0.031). At variance with previous determination,\nindicating a stable liquid phase for Cw < Cw*=0.015-0.018, we find that the\ngelation takes actually place in the whole examined Cw range. More importantly,\nwe find that Cw* marks the transition between two different routes to gelation.\nWe hypothesize that at low concentration Laponite suspension behaves as an\nattractive colloid and that the slowing down of the dynamics is attained by the\nformation of larger and larger clusters while at high concentration the basic\nunits of the gel could be the Debye Huckel spheres associated to single\nLaponite plates."
    },
    {
        "anchor": "Self-organisation of tip functionalised elongated colloidal particles: Weakly attractive interactions between the tips of rod-like colloidal\nparticles affect their liquid-crystal phase behaviour due to a subtle interplay\nbetween enthalpy and entropy. Here, we employ molecular dynamics simulations on\nsemi-flexible, repulsive bead-spring chains of which one of the two end beads\nattract each other. We calculate the phase diagram as a function of both the\nvolume fraction of the chains and the strength of the attractive potential. We\nidentify a large number of phases that include isotropic, nematic, smectic A,\nsmectic B and crystalline states. For tip attraction energies lower than the\nthermal energy, our results are qualitatively consistent with experimental\nfindings: we find that an increase of the attraction strength shifts the\nnematic to smectic A phase transition to lower volume fractions, with only\nminor effect on the stability of the other phases. For sufficiently strong tip\nattraction, the nematic phase disappears completely, in addition leading to the\ndestabilisation of the isotropic phase. In order to better understand the\nunderlying physics of these phenomena, we also investigate the clustering of\nthe particles at their attractive tips and the effective molecular field\nexperienced by the particles in the smectic A phase. Based on these results, we\nargue that the clustering of the tips only affects the phase stability if\nlamellar structures (``micelles'') are formed. We find that an increase of the\nattraction strength increases the degree of order in the layered\nphases.Interestingly, we also find evidence for the existence of an\nanti-ferroelectric smectic A phase transition induced by the interaction\nbetween the tips. A simple Maier-Saupe-McMillan model confirms our findings.",
        "positive": "Tailoring the flow of soft glasses by soft additives: We examine the vitrification and melting of asymmetric star polymers mixtures\nby combining rheological measurements with mode coupling theory. We identify\ntwo types of glassy states, a {\\it single} glass, in which the small component\nis fluid in the glassy matrix of the big one and a {\\it double} glass, in which\nboth components are vitrified. Addition of small star polymers leads to melting\nof {\\it both} glasses and the melting curve has a non-monotonic dependence on\nthe star-star size ratio. The phenomenon opens new ways for externally steering\nthe rheological behavior of soft matter systems."
    },
    {
        "anchor": "Coarse-graining amorphous plasticity: impact of rejuvenation and\n  disorder: The coarse-graining of amorphous plasticity from the atomistic to the\nmesoscopic scale is studied in the framework of a simple scalar elasto-plastic\nmodel. Building on recent results obtained on the atomistic scale, we discuss\nthe interest in a disordered landscape-informed threshold disorder to reproduce\nthe physics of amorphous plasticity. We show that accounting for a rejuvenation\nscenario allows us to reproduce quasi-quantitatively the evolution of the mean\nlocal yield stress and the localization behavior. We emphasize the crucial role\nof two dimensionless parameters: the relative strength of the yield stress\ndisorder with respect to the typical stress drops associated with a plastic\nrearrangement, and the age parameter characterizing the relative stability of\nthe initial glass with respect to the rejuvenated glass that emerges upon shear\ndeformation.",
        "positive": "Bond Orientational Order Parameters in the Crystalline Phases of the\n  Classical Yukawa-Wigner Bilayers: We present a study of the structural properties of the crystalline phases for\na planar bilayer of particles interacting via repulsive Yukawa potentials in\nthe weak screening region. The study is done with Monte Carlo computations and\nthe long ranged contributions to energy are taken into account with the Ewald\nmethod for quasi-two dimensional systems. Two first order phase transitions\n(fluid-solid and solid-solid) and one second order transition (solid-solid) are\nfound when the surface density is varied at constant temperature. A particular\nattention is pay to the characteristics of the crystalline phases by the\nanalysis of bond orientational order parameters and center-to-center\ncorrelations functions."
    },
    {
        "anchor": "Geometric control of tilt transition dynamics in single-clamped\n  thermalized elastic sheets: We study the finite-temperature dynamics of thin elastic sheets in a\nsingle-clamped cantilever configuration. This system is known to exhibit a tilt\ntransition at which the preferred mean plane of the sheet shifts from\nhorizontal to a plane above or below the horizontal. The resultant thermally\nroughened two-state (up/down) system possesses rich dynamics on multiple time\nscales. In the tilted regime, a finite energy barrier separates the\nspontaneously chosen up state from the inversion-symmetric down state.\nMolecular dynamics simulations confirm that over a sufficiently long time, such\nthermalized elastic sheets transition between the two states, residing in each\nfor a finite dwell time. One might expect that temperature is the primary\ndriver for tilt inversion. We find, instead, that the primary control\nparameter, at fixed tilt order parameter, is the dimensionless and purely\ngeometrical aspect ratio of the clamped width to the total length of the\notherwise-free sheet. Using a combination of an effective mean-field theory and\nKramers' theory, we derive the transition rate and examine its asymptotic\nbehavior. At length scales beyond a material-dependent thermal length scale,\nrenormalization of the elastic constants qualitatively modifies the temperature\nresponse. In particular, the transition is suppressed by thermal fluctuations,\nenhancing the robustness of the tilted state. We check and supplement these\nfindings with further molecular dynamics simulations for a range of aspect\nratios and temperatures.",
        "positive": "An energy-landscape-based crossover temperature in glass-forming liquids: The systematic identification of temperature scales in supercooled liquids\nthat are key to understanding those liquids' underlying glass properties, and\nthe latter's formation-history dependence, is a challenging task. Here we study\nthe statistics of particles' squared displacements $\\delta r^2$ between\nequilibrium liquid configurations at temperature $T$, and their underlying\ninherent states, using computer simulations of 11 different\ncomputer-glass-formers. We show that the relative fluctuations of $\\delta r^2$\nare nonmonotonic in $T$, exhibiting a maximum whose location defines the\ncrossover temperature $T_{\\small{\\mathsf{X}}}$. Therefore,\n$T_{\\small{\\mathsf{X}}}$ marks the point of maximal heterogeneity during the\nprocess of tumbling down the energy landscape, starting from an equilibrium\nliquid state at temperature $T$, down to its underlying inherent state. We\nextract $T_{\\small{\\mathsf{X}}}$ for the 11 employed computer glasses, ranging\nfrom tetrahedral glasses to packings of soft elastic spheres, and demonstrate\nits usefulness in putting the elastic properties of different glasses on the\nsame footing. Interestingly, we further show that $T_{\\small{\\mathsf{X}}}$\nmarks the crossover between two distinct regimes of the mean $\\langle\\delta\nr^2\\rangle$: a high temperature regime in which $\\langle\\delta r^2\\rangle$\nscales approximately as $T^{0.5}$, and a deeply-supercooled regime in which\n$\\langle\\delta r^2\\rangle$ scales approximately as $T^{1.3}$. Further research\ndirections are discussed."
    },
    {
        "anchor": "Shear-induced first-order transition in polar liquid crystals: The hydrodynamic theory of polar liquid crystals is widely used to describe\nbiological active fluids as well as passive molecular materials. Depending on\nthe `shear-alignment parameter', in passive or weakly active polar fluids under\nexternal shear the polar order parameter ${\\mathbf{p}}$ is either inclined to\nthe flow at a fixed (Leslie) angle, or rotates continuously. Here we study the\nrole of an additional `shear-elongation parameter' that has been neglected in\nthe recent literature and causes $|{\\mathbf{p}}|$ to change under flow. We show\nthat this effect can give rise to a shear-induced first order phase transition\n%(instead of the usual second order transition) from isotropic to polar, and\nsignificantly change the rheological properties of both active and passive\npolar fluids.",
        "positive": "Dipolar correlations in structured solvents under nanoconfinement: We study electrostatic correlations in structured solvents confined to\nnanoscale systems. We derive variational equations of Netz-Orland type for a\nmodel liquid composed of finite size dipoles. These equations are solved for\nboth dilute solvents and solvents at physiological concentrations in a slit\nnanopore geometry. Correlation effects are of major importance for the\ndielectric reduction and anisotropy of the solvent resulting from dipole image\ninteractions and also lead to a reduction of van der Waals attractions between\nlow dielectric bodies. Finally, by comparison with other recently developed\nself-consistent theories and experiments, we scrutinize the effect of\nsolvent-membrane interactions on the differential capacitance of the charged\nliquid in contact with low dielectric substrates. The interfacial solvent\ndepletion driven by solvent-image interactions plays the major role in the\nobserved low values of the experimental capacitance data, while non-locality\nassociated with the extended charge structure of solvent molecules only brings\na minor contribution."
    },
    {
        "anchor": "Rectification properties of conically shaped nanopores: consequences of\n  miniaturization: Nanopores attracted a great deal of scientific interest as templates for\nbiological sensors as well as model systems to understand transport phenomena\nat the nanoscale. The experimental and theoretical analysis of nanopores has\nbeen so far focused on understanding the effect of the pore opening diameter on\nionic transport. In this article we present systematic studies on the\ndependence of ion transport properties on the pore length. Particular attention\nwas given to the effect of ion current rectification exhibited for conically\nshaped nanopores with homogeneous surface charges. We found that reducing the\nlength of conically shaped nanopores significantly lowered their ability to\nrectify ion current. However, rectification properties of short pores can be\nenhanced by tailoring the surface charge and the shape of the narrow opening.\nFurthermore we analyze the relationship of the rectification behavior and ion\nselectivity for different pore lengths. All simulations were performed using\nMsSimPore, a software package for solving the Poisson-Nernst-Planck (PNP)\nequations. It is based on a novel finite element solver and allows for\nsimulations up to surface charge densities of -2 e/nm^2. MsSimPore is based on\n1D reduction of the PNP model, but allows for a direct treatment of the pore\nwith bulk electrolyte reservoirs, a feature which was previously used in higher\ndimensional models only. MsSimPore includes these reservoirs in the\ncalculations; a property especially important for short pores, where the ionic\nconcentrations and the electric potential vary strongly inside the pore as well\nas in the regions next to pore entrance.",
        "positive": "Long-range hydrodynamic effect due to a single vesicle in linear flow: Vesicles are involved in a vast variety of transport processes in living\norganisms. Additionally, they serve as a model for the dynamics of cell\nsuspensions. Predicting the rheological properties of their suspensions is\nstill an open question, as even the interaction of pairs is yet to be fully\nunderstood. Here we analyse the effect of a single vesicle, undergoing\ntank-treading motion, on its surrounding shear flow by studying the induced\ndisturbance field $\\delta \\vec{V}$, the difference between the velocity field\nin its presence and absence. The comparison between experiments and numerical\nsimulations reveals an impressive agreement. Tracking ridges in the disturbance\nfield magnitude landscape, we identify the principal directions along which the\nvelocity difference field is analysed in the vesicle vicinity. The disturbance\nmagnitude is found to be significant up to about 4 vesicles radii and can be\ndescribed by a power law decay with the distance $d$ from the vesicle $ \\|\n\\delta \\vec{V} \\| \\propto d^{-3/2}$. This is consistent with previous\nexperimental results on the separation distance between two interacting\nvesicles under similar conditions, for which their dynamics is altered. This is\nan indication of vesicles long-range effect via the disturbance field and calls\nfor the proper incorporation of long-range hydrodynamic interactions when\nattempting to derive rheological properties of vesicle suspensions."
    },
    {
        "anchor": "A Percolation Model of Diagenesis: The restructuring process of diagenesis in the sedimentary rocks is studied\nusing a percolation type model. The cementation and dissolution processes are\nmodeled by the culling of occupied sites in rarefied and growth of vacant sites\nin dense environments. Starting from sub-critical states of ordinary\npercolation the system evolves under the diagenetic rules to critical\npercolation configurations. Our numerical simulation results in two dimensions\nindicate that the stable configuration has the same critical behaviour as the\nordinary percolation.",
        "positive": "Modulating internal transition kinetics in responsive macromolecules by\n  collective crowding: Packing and crowding are used in biology as mechanisms to (self-)regulate\ninternal molecular or cellular processes based on collective signalling. Here,\nwe study how the transition kinetics of an internal switch of responsive\nmacromolecules is modified collectively by their spatial packing. We employ\nBrownian dynamics simulations of a model of responsive colloids (RCs), in which\nan explicit internal degree of freedom, here, the particle size, moving in a\nbimodal energy landscape responds self-consistently to the density fluctuations\nof the crowded environment. We demonstrate that populations and transition\ntimes for the two-state switching kinetics can be tuned over one order of\nmagnitude by self-crowding. An exponential scaling law derived from a\ncombination of Kramers' and liquid state perturbation theory is in very good\nagreement with the simulations."
    },
    {
        "anchor": "Electrostatic stability and encapsidation of charged nano-droplets: We investigate electrostatic stability of charged droplets, modeled as\npermeable, charged spheres, and their encapsidation in thin, arbitrarily\ncharged nano-shells, immersed in a neutralizing asymmetric electrolyte\nbackground. The latter consists of a small concentration of mobile multivalent\ncounterions in a bathing solution of monovalent (positive and negative) ions.\nWe use extensive Monte-Carlo simulations to investigate the spatial\ndistribution of multivalent counterions and the electrostatic component of\ntheir osmotic pressure on the bounding surface of the spherical nano-shell. The\nosmotic pressure can be negative (inward pressure), positive (outward pressure)\nor zero, depending on the system parameters such as the charge density of the\ndroplet, the charge density of the shell, and the electrolyte screening, which\nthus determine the stability of the nano-container. The counter-intuitive\neffects of multivalent counterions comprise the increased stability of the\ncharged droplet with larger charge density, increased stability in the case of\nencapsidating shell of charge density of the same sign as the charged droplet,\nas well as the possibility to dispense altogether with the encapsidating shell,\nits confining effect taken over by the multivalent counterions. These dramatic\neffects are in stark contrast to the conventional mean-field picture, which in\nparticular implies that a more highly charged spherical droplet should be\nelectrostatically less stable because of its larger (repulsive) self-energy.",
        "positive": "Elastic Orbital Angular Momentum: We identify that flexural guided elastic waves in elastic pipes carry a\nwell-defined orbital angular momentum associated with the compressional\ndilatational potential. This enables the transfer of elastic orbital angular\nmomentum, that we numerically demonstrate, through the coupling of the\ncompressional potential in a pipe to the acoustic pressure field in a\nsurrounding fluid in contact with the pipe."
    },
    {
        "anchor": "Live Soap: Order, Fluctuations and Instabilities in Active Smectics: We construct a hydrodynamic theory of noisy, apolar active smectics, in bulk\nsuspension or on a substrate. Our predictions include: quasi-long-ranged\nsmectic order in dimension d = 2, and long- ranged in d = 3, extending\npreviously published results to all dynamical regimes; Kosterlitz-Thouless\nmelting to an active nematic at high and low concentrations in d = 2; nonzero\nsecond-sound speed parallel to the layers; the suppression of giant number\nfluctuations by smectic elasticity; instability to spontaneous undulation and\nflow in bulk contractile smectics; a layer spacing instability, possibly\noscillatory, for large enough extensile active stresses.",
        "positive": "Generation of mechanical force by grafted polyelectrolytes in an\n  electric field: We study theoretically and by means of molecular dynamics (MD) simulations\nthe generation of mechanical force by grafted polyelectrolytes in an external\nelectric field, which favors its adsorption on the grafting plane. The force\narises in deformable bodies linked to the free end of the chain. Varying the\nfield, one controls the length of the non-adsorbed part of the chain and hence\nthe deformation of the target body, i.e., the arising force too. We consider\ntarget bodies with a linear force-deformation relation and with a Hertzian one.\nWhile the first relation models a coiled Gaussian chain, the second one\ndescribes the force response of a squeezed colloidal particle. The theoretical\ndependencies of generated force and compression of the target body on applied\nfield agree very well with the results of MD simulations. The analyzed\nphenomenon may play an important role in a future nano-machinery, e.g. it may\nbe used to design nano-vices to fix nano-sized objects."
    },
    {
        "anchor": "Aging in a Laponite colloidal suspension: A Brownian dynamics simulation\n  study: We report Brownian dynamics simulation of the out-of-equilibrium dynamics\n(aging) in a colloidal suspension composed of rigid charged disks, one possible\nmodel for Laponite, a synthetic clay deeply investigated in the last few years\nby means of various experimental techniques. At variance with previous\nnumerical investigations, mainly focusing on static structure and equilibrium\ndynamics, we explore the out-of-equilibrium aging dynamics. We analyze the\nwave-vector and waiting time dependence of the dynamics, focusing on the\nsingle-particle and collective density fluctuations (intermediate scattering\nfunctions), the mean squared displacement and the rotational dynamics. Our\nfindings confirm the complexity of the out-of-equilibrium dynamical behavior of\nthis class of colloidal suspensions and suggest that an arrested disordered\nstate driven by a repulsive Yukawa potential, i.e., a Wigner glass can be\nobserved in this model.",
        "positive": "Energy Absorption and Low Velocity Impact Response of Open-Cell Polyurea\n  Foams: The energy absorption and impact attenuation of low density polyurea (PU)\nfoams (140 - 220 kg/m3) is presented. The stress-strain behavior, energy\nabsorption, cushioning efficiency, and energy return (resilience) are measured\nat a quasi-static strain rate using an Instron load frame. In addition, the low\nvelocity impact attenuation of the polyurea foams at 5 J and 7 J impact\nenergies were investigated according to the American Society for Testing and\nMaterials (ASTM) test methods F1976. The polyurea foams were then compared with\nwidely used ethylene vinyl acetate (EVA) and thermoplastic polyurethane (TPU)\nfoam technologies at similar densities. The PU foams displayed a 5 % increase\nin cushioning efficiency and 30 % greater energy absorption over TPU and EVA\nfoams under quasi-static compression. Under impact testing, PU foams resulted\nin a reduction of up to 28.6 % and 36.9 % in peak transmitted impact forces\nwhen compared to EVA and TPU foams of the same thickness (20 mm) at 5 J and 7\nJ, respectively. These properties should allow these materials to have a wide\nrange of cushioning/impact applications, especially in protective body and\nheadgear systems."
    },
    {
        "anchor": "Solvent fluctuations around solvophobic, solvophilic and patchy\n  nanostructures and the accompanying solvent mediated interactions: Using classical density functional theory (DFT) we calculate the density\nprofile $\\rho({\\mathbf r})$ and local compressibility $\\chi({\\mathbf r})$ of a\nsimple liquid solvent in which a pair of blocks with (microscopic) rectangular\ncross-section are immersed. We consider blocks that are solvophobic,\nsolvophilic and also ones that have both solvophobic and solvophilic patches.\nLarge values of $\\chi({\\mathbf r})$ correspond to regions in space where the\nliquid density is fluctuating most strongly. We seek to elucidate how enhanced\ndensity fluctuations correlate with the solvent mediated force between the\nblocks, as the distance between the blocks and the chemical potential of the\nliquid reservoir vary. For sufficiently solvophobic blocks, at small block\nseparations and small deviations from bulk gas-liquid coexistence, we observe a\nstrongly attractive (near constant) force, stemming from capillary evaporation\nto form a low density gas-like intrusion between the blocks. The accompanying\n$\\chi({\\mathbf r})$ exhibits structure which reflects the incipient gas-liquid\ninterfaces that develop. We argue that our model system provides a means to\nunderstanding the basic physics of solvent mediated interactions between\nnanostructures, and between objects such as proteins in water, that possess\nhydrophobic and hydrophilic patches.",
        "positive": "Unsteady flow, clusters and bands in a model shear-thickening fluid: We analyse the flow curves of a two-dimensional assembly of granular\nparticles which are interacting via frictional contact forces. For packing\nfractions slightly below jamming, the fluid undergoes a large scale\ninstability, implying a range of stress and strainrates where no stationary\nflow can exist. Whereas small systems were shown previously to exhibit\nhysteretic jumps between the low and high stress branches, large systems\nexhibit continuous shear thickening arising from averaging unsteady, spatially\nheterogeneous flows. The observed large scale patterns as well as their\ndynamics are found to depend on strainrate: At the lower end of the unstable\nregion, force chains merge to form giant bands that span the system in\ncompressional direction and propagate in dilational direction. At the upper\nend, we observe large scale clusters which extend along the dilational\ndirection and propagate along the compressional direction. Both patterns, bands\nand clusters, come in with infinite correlation length similar to the sudden\nonset of system-spanning plugs in impact experiments."
    },
    {
        "anchor": "Capillary Fluctuations and Film-Height-Dependent Surface Tension of an\n  Adsorbed Liquid Film: Our understanding of both structure and dynamics of adsorbed liquids heavily\nrelies on the capillary wave Hamiltonian, but a thorough test of this model is\nstill lacking. Here we study the capillary wave fluctuations of a liquid film\nwith short range forces adsorbed on a solid exhibiting van der Waals\ninteractions. We show for the first time that the measured capillary wave\nspectrum right above the first order wetting transition provides an interface\npotential consistent with independent calculations from thermodynamic\nintegration. However, the surface tension exhibits an oscillatory film thick\ndependence which reveals a hitherto unnoticed capillary wave broadening\nmechanism beyond mere interfacial displacements.",
        "positive": "Defect-polymorphism controlled electrophoretic propulsion of anisometric\n  microparticles in a nematic liquid crystal: Nontrivial shape of colloidal particles create complex elastic distortions\nand topological defects in liquid crystals and play a key role in governing\ntheir electrophoretic propulsion through the medium. Here, we report\nexperimental results on defects and electrophoretic transport of anisometric\n(snowman-shaped) dielectric particles subjected to an alternating electric\nfield perpendicular to the director in a nematic liquid crystal. We demonstrate\nthat the shape asymmetry gives rise to defect-polymorphism by nucleating point\nor ring defects at multiple locations on the particle and controls the\ndirection as well as the magnitude of the electrophoretic propulsion. Our\nfindings unveil a novel degree of freedom in translocating microparticles in\nliquid crystals for applications in microfluidics, controlled transport and\nassembly."
    },
    {
        "anchor": "Model for disordered proteins with strongly sequence-dependent liquid\n  phase behavior: Phase separation of intrinsically disordered proteins is important for the\nformation of membraneless organelles, or biomolecular condensates, which play\nkey roles in the regulation of biochemical processes within cells. In this\nwork, we investigated the phase separation of different sequences of a\ncoarse-grained model for intrinsically disordered proteins and discovered a\nsurprisingly rich phase behavior. We studied both the fraction of total\nhydrophobic parts and the distribution of hydrophobic parts. Not surprisingly,\nsequences with larger hydrophobic fractions showed conventional liquid-liquid\nphase separation. The location of the critical point was systematically\ninfluenced by the terminal beads of the sequence, due to changes in interfacial\ncomposition and tension. For sequences with lower hydrophobicity, we observed\nnot only conventional liquid-liquid phase separation, but also reentrant phase\nbehavior, in which the liquid phase density decreases at lower temperatures.\nFor some sequences, we observed formation of open phases consisting of\naggregates, rather than a normal liquid. These aggregates had overall lower\ndensities than the conventional liquid phases, and exhibited complex geometries\nwith large interconnected string-like or membrane-like clusters. Our findings\nsuggest that minor alterations in the ordering of residues may lead to large\nchanges in the phase behavior of the protein, a fact of significant potential\nrelevance for biology.",
        "positive": "Calculation of a Deuterium Double Shock Hugoniot from Ab initio\n  Simulations: We calculate the equation of state of dense deuterium with two ab initio\nsimulations techniques, path integral Monte Carlo and density functional theory\nmolecular dynamics, in the density range of 0.67 < rho < 1.60 g/cc. We derive\nthe double shock Hugoniot and compare with the recent laser-driven double shock\nwave experiments by Mostovych et al. [1]. We find excellent agreement between\nthe two types of microscopic simulations but a significant discrepancy with the\nlaser-driven shock measurements."
    },
    {
        "anchor": "Spinor condensates and light scattering from Bose-Einstein condensates: These notes discuss two aspects of the physics of atomic Bose-Einstein\ncondensates: optical properties and spinor condensates. The first topic\nincludes light scattering experiments which probe the excitations of a\ncondensate in both the free-particle and phonon regime. At higher light\nintensity, a new form of superradiance and phase-coherent matter wave\namplification were observed. We also discuss properties of spinor condensates\nand describe studies of ground--state spin domain structures and dynamical\nstudies which revealed metastable excited states and quantum tunneling.",
        "positive": "Geometry-induced rectification for an active object: Study on a rectified current induced by active particles has received a great\nattention due to its possible application to a microscopic motor in biological\nenvironments. Insertion of an {\\em asymmetric} passive object amid many active\nparticles has been regarded as an essential ingredient for generating such a\nrectified motion. Here, we report that the reverse situation is also possible,\nwhere the motion of an active object can be rectified by its geometric\nasymmetry amid many passive particles. This may describe an unidirectional\nmotion of polar biological agents with asymmetric shape. We also find a weak\nbut less diffusive rectified motion in a {\\em passive} mode without energy\npump-in. This \"moving by dissipation\" mechanism could be used as a design\nprinciple for developing more reliable microscopic motors."
    },
    {
        "anchor": "Stress control in non-ideal topological Maxwell lattices via geometry: Topological mechanical metamaterials have demonstrated exotic and robust\nmechanical properties which led to promising engineering applications. One of\nsuch properties is the focusing of stress at the interface connecting domains\nof topological Maxwell lattices of opposite topological polarizations, which\nprotects the bulk of the material against fracturing. Here we generalize this\ntheory to non-ideal Maxwell lattices, incorporate real material features that\nleads to interactions beyond previous ideal models. By quantitative analysis of\nstress distributions of topological Maxwell lattices with self-stress\ninterfaces theoretically and computationally, we propose a design rule that\nminimizes stress in the bulk of the material. This design rule can guide the\nrealization of stress focusing and fracturing protection in real materials.",
        "positive": "Orientation and dynamics of stiff polymeric nanoparticles: Successful assembly of suspended nanoscale rod-like particles depends on\nfundamental phenomena controlling rotational and translational diffusion.\nDespite the significant developments in fluidic fabrication of nanostructured\nmaterials, the ability to quantify the dynamics in processing systems remains\nchallenging. Here we demonstrate an experimental method for characterization of\nthe orientation dynamics of nanorod suspensions in assembly flows using\nbirefringence relaxation. The methodology is illustrated using nanocelluloses\n(cellulose nanocrystals and nanofibrils) as model systems, where the coupling\nof rotational diffusion coefficients to particle size distributions as well as\nflow-induced orientation mechanisms are elucidated. Our observations advance\nthe knowledge on key fundamental nanoscale mechanisms governing the dynamics of\nnanotubes and nanorods allowing bottom-up assembly into hierarchical\nsuperstructures."
    },
    {
        "anchor": "Printing surface charge as a new paradigm to program droplet transport: Directed, long-range and self-propelled transport of droplets on solid\nsurfaces, especially on water repellent surfaces, is crucial for many\napplications from water harvesting to bio-analytical devices. One appealing\nstrategy to achieve the preferential transport is to passively control the\nsurface wetting gradients, topological or chemical, to break the asymmetric\ncontact line and overcome the resistance force. Despite extensive progress, the\ndirectional droplet transport is limited to small transport velocity and short\ntransport distance due to the fundamental trade-off: rapid transport of droplet\ndemands a large wetting gradient, whereas long-range transport necessitates a\nrelatively small wetting gradient. Here, we report a radically new strategy\nthat resolves the bottleneck through the creation of an unexplored gradient in\nsurface charge density (SCD). By leveraging on a facile droplet printing on\nsuperamphiphobic surfaces as well as the fundamental understanding of the\nmechanisms underpinning the creation of the preferential SCD, we demonstrate\nthe self-propulsion of droplets with a record-high velocity over an ultra-long\ndistance without the need for additional energy input. Such a Leidenfrost-like\ndroplet transport, manifested at ambient condition, is also genetic, which can\noccur on a variety of substrates such as flexible and vertically placed\nsurfaces. Moreover, distinct from conventional physical and chemical gradients,\nthe new dimension of gradient in SCD can be programmed in a rewritable fashion.\nWe envision that our work enriches and extends our capability in the\nmanipulation of droplet transport and would find numerous potential\napplications otherwise impossible.",
        "positive": "Rheological behaviour of suspensions of bubbles in yield stress fluids: The rheological properties of suspensions of bubbles in yield stress fluids\nare investigated through experiments on model systems made of monodisperse\nbubbles dispersed in concentrated emulsions. Thanks to this highly tunable\nsystem, the bubble size and the rheological properties of the suspending yield\nstress fluid are varied over a wide range. We show that the macroscopic\nresponse under shear of the suspensions depends on the gas volume fraction and\nthe bubble stiffness in the suspending fluid. This relative stiffness can be\nquantified through capillary numbers comparing the capillary pressure to stress\nscales associated with the rheological properties of the suspending fluid. We\ndemonstrate that those capillary numbers govern the decrease of the elastic and\nloss moduli, the absence of variation of the yield stress and the increase of\nthe consistency with the gas volume fraction, for the investigated range of\ncapillary numbers. Micro-mechanical estimates are consistent with the\nexperimental data and provide insight on the experimental results."
    },
    {
        "anchor": "Solidification and superlubricity with molecular alkane films: Hydrocarbon films confined between smooth mica surfaces have long provided an\nexperimental playground for model studies of structure and dynamics of confined\nliquids. However fundamental questions regarding the phase behavior and shear\nproperties in this simple system remain unsolved. With ultra-sensitive\nresolution in film thickness and shear stress, and control over the\ncrystallographic alignment of the confining surfaces, we here investigate the\nshear forces transmitted across nanoscale films of dodecane down to a single\nmolecular layer. We resolve the conditions under which liquid-solid phase\ntransitions occur and explain friction coefficients spanning several orders of\nmagnitude. We find that commensurate surface alignment and presence of water at\nthe interfaces each lead to moderate or high friction, whereas friction\ncoefficients down to 0.001 are observed for a single molecular layer of\ndodecane trapped between crystallographically misaligned dry surfaces. This\nultralow friction is attributed to sliding at the incommensurate interface\nbetween one of the mica surfaces and the laterally ordered solid molecular\nfilm, reconciling previous interpretations.",
        "positive": "Critical confinement and elastic instability in thin solid films: When a flexible plate is peeled off a thin and soft elastic film bonded to a\nrigid support, uniformly spaced fingering patterns develop along their line of\ncontact. While, the wavelength of these patterns depends only on the thickness\nof the film, their amplitude varies with all material and geometric properties\nof the film and that of the adhering plate. Here we have analyzed this\ninstability by the regular perturbation technique to obtain the excess\ndeformations of the film over and above the base quantities. Furthermore, by\ncalculating the excess energy of the system we have shown that these excess\ndeformations, associated with the instability, occur for films which are\ncritically confined. We have presented two different experiments for\ncontrolling the degree of confinement: by pre-stretching the film and by\nadjusting the contact width between the film and the plate."
    },
    {
        "anchor": "Solubility of organic salts in solvent-antisolvent mixtures: A combined\n  experimental and molecular dynamics simulations approach: We combine molecular dynamics simulations with experiments to estimate\nsolubilities of organic salts in complex growth environments. We predict the\nsolubility by simulations of the growth and dissolution of ions at the crystal\nsurface kink sites at different solution concentrations. Thereby, the\nsolubility is identified as the solution's salt concentration, where the energy\nof the ion pair dissolved in solution equals the energy of the ion pair\ncrystallized at the kink sites. The simulation methodology is demonstrated for\nthe case of anhydrous sodium acetate crystallized from various\nsolvent-antisolvent mixtures. To validate the predicted solubilities, we have\nmeasured the solubilities of sodium acetate in-house, using an experimental\nsetup and measurement protocol that guarantees moisture-free conditions, which\nis key for a hygroscopic compound like sodium acetate. We observe excellent\nagreement between the experimental and the computationally evaluated\nsolubilities for sodium acetate in different solvent-antisolvent mixtures.\nGiven the agreement and the rich data the simulations produce, we can use them\nto complement experimental tasks which in turn will reduce time and capital in\nthe design of complicated industrial crystallization processes of organic\nsalts.",
        "positive": "On the composition dependence of the microscopic structure,\n  thermodynamic, dynamic and dielectric properties of water-dimethyl formamide\n  model mixtures. Molecular dynamics simulation results: Isothermal-isobaric molecular dynamics simulations have been performed to\nexamine an ample set of properties of the model water-N,N-dimethylformamide\n(DMF) mixture as a function of composition. The SPC-E and TIP4P-Ew water models\ntogether with two united atom models for DMF [Chalaris M., Samios J., J. Chem.\nPhys., 2000, 112, 8581; Cordeiro J., Int. J. Quantum Chem., 1997, 65, 709] were\nused. Our principal analyses concern the behaviour of structural properties in\nterms of radial distribution functions, and the number of hydrogen bonds\nbetween molecules of different species as well as thermodynamic properties.\nNamely, we explore the density, excess mixing molar volume and enthalpy, the\nheat capacity and excess mixing heat capacity. Finally, the self-diffusion\ncoefficients of species and the dielectric constant of the system are\ndiscussed. In addition, surface tension of water-DMF mixtures has been\ncalculated and analyzed."
    },
    {
        "anchor": "Unfolding of Crumpled Thin Sheets: Crumpled thin sheets are complex fractal structures whose physical properties\nare influenced by a hierarchy of ridges. In this Letter, we report experiments\nthat measure the stress-strain relation and show the coexistence of phases in\nthe stretching of crumpled surfaces. The pull stress showed a change from a\nlinear Hookean regime to a sublinear scaling with an exponent of $0.65 \\pm\n0.03$, which is identified with the Hurst exponent of the crumpled sheets. The\nstress fluctuations are studied, the statistical distribution of force peaks is\nanalyzed and it is shown how the unpacking of crumpled sheets is guided by long\ndistance interactions.",
        "positive": "Segregated structure of ring polymer melts near the surface: Molecular\n  dynamics simulation study: We study structural properties of a ring polymeric melt confined in a film in\ncomparison to a linear counterpart using molecular dynamics simulations. Local\nstructure orderings of ring and linear polymers in the vicinity of the surface\nare similar to each other because the length scale of surface-monomer excluded\nvolume interaction is smaller than the size of an ideal blob of the ring. In a\nlong length scale, while the Silberberg hypothesis can be used to provide a\nphysical origin of confined linear polymer results, it no longer holds for a\nring polymer case. We also present different structural properties of ring and\nlinear polymers in a melt, including the size of polymers, an adsorbed amount,\nand the coordination number of a polymer. Our observation reveals that a\nconfined ring in a melt adopts highly segregated conformation due to a\ntopological excluded volume repulsion, which may provide a new perspective to\nunderstand the nature of biological processes, such as territorial segregation\nof chromosomes in eukaryotic nuclei."
    },
    {
        "anchor": "Generation of Multiple Circular Walls on a Thin Film of Nematic Liquid\n  Crystal by Laser Scanning: We found that multiple circular walls (MCW) can be generated on a thin film\nof a nematic liquid crystal through a spiral scanning of a focused IR laser.\nThe ratios between radii of adjacent rings of MCW were almost constant. These\nconstant ratios can be explained theoretically by minimization of the Frank\nelastic free energy of nematic medium. The director field on a MCW exhibits\nchiral symmetry-breaking although the elastic free energies of both chiral MCWs\nare degenerated, i.e., the director on a MCW can rotate clockwise or\ncounterclockwise along the radial direction.",
        "positive": "Roughness-dependent tribology effects on discontinuous shear thickening: Surface roughness affects many properties of colloids, from depletion [1] and\ncapillary interactions [2], to their dispersibility [3] and use as emulsion\nstabilizers [4]. It also impacts particle-particle frictional contacts, which\nhave recently emerged as being responsible for the discontinuous shear\nthickening (DST) of dense suspensions [5-17]. Tribological properties of these\ncontacts have been rarely experimentally accessed [6, 15, 17, 18], especially\nfor non-spherical particles. Here, we systematically tackle the effect of\nnanoscale surface roughness by producing a library of all-silica,\nraspberry-like colloids [19] and linking their rheology to their tribology.\nRougher surfaces lead to a significant anticipation of DST onset, both in terms\nof shear rate and solid loading. Strikingly, they also eliminate continuous\nthickening. DST is here due to the interlocking of asperities, which we have\nidentified as \"stick-slip\" frictional contacts by measuring the sliding of the\nsame particles via lateral force microscopy (LFM). Direct measurements of\nparticle-particle friction therefore highlight the value of an\nengineering-tribology approach to tuning the thickening of suspensions."
    },
    {
        "anchor": "Two comments on adhesion: The adhesion paradox refers to the observation that for most solid objects no\nadhesion can be detected when they are separated from a state of molecular\ncontact. The adhesion paradox results from surface roughness, and we present\nexperimental and theoretical results which shows that adhesion in most cases is\n\"killed\" by the longest wavelength roughness. Adhesion experiments between a\nhuman finger and a clean glass plate were carried out, and for a dry finger, no\nmacroscopic adhesion occurred. We suggest that the observed decrease in the\ncontact area with increasing shear force results from non-adhesive finger-glass\ncontact mechanics, involving large deformations of a complex layered material.",
        "positive": "Forecasting failure locations in two-dimensional disordered lattices: Forecasting fracture locations in a progressively failing disordered\nstructure is of paramount importance when considering structural materials. We\nexplore this issue for gradual deterioration via beam breakage of\ntwo-dimensional disordered lattices, which we represent as networks, for\nvarious values of mean degree. We study experimental samples with geometric\nstructures that we construct based on observed contact networks in 2D granular\nmedia. We calculate geodesic edge betweenness centrality, which helps quantify\nwhich edges are on many shortest paths in a network, to forecast the failure\nlocations. We demonstrate for the tested samples that, for a variety of failure\nbehaviors, failures occur predominantly at locations that have larger geodesic\nedge betweenness values than the mean one in the structure. Because only a\nsmall fraction of edges have values above the mean, this is a relevant\ndiagnostic to assess failure locations. Our results demonstrate that one can\nconsider only specific parts of a system as likely failure locations and that,\nwith reasonable success, one can assess possible failure locations of a\nstructure without needing to study its detailed energetic states."
    },
    {
        "anchor": "Effect of edge disturbance on shear banding in polymeric solutions: Edge instabilities are believed to be one of the possible causes of shear\nbanding in entangled polymeric fluids. Here, we investigate the effect of edge\ndisturbance on the shear-induced dynamics of well-entangled DNA solutions.\nUsing a custom high-aspect-ratio planar-Couette cell, we systematically measure\nthe velocity profiles of sheared DNA samples at different distances away from\nthe edge of the shear cell. Under a weak oscillatory shear with the\ncorresponding Weissenberg number (Wi) smaller than 1, where DNA solutions\nexhibit linear velocity profiles with strong wall slip, the penetration depth\nof the edge disturbance is on the order of the gap thickness of the shear cell,\nconsistent with the behavior of Newtonian fluids. However, under a strong\noscillatory shear with Wi > 1 that produces shear-banding flows, the\npenetration depth is an order of magnitude larger than the gap thickness and\nbecomes spatially anisotropic. Moreover, we find that the shear-banding flows\npersist deep inside the sheared sample, where the effect of edge disturbance\ndiminishes. Hence, our experiments demonstrate an abnormally long penetration\ndepth of edge disturbance and illustrate the bulk nature of shear-banding flows\nof entangled polymeric fluids under time-dependent oscillatory shear.",
        "positive": "Antibubbles enable tunable payload release with low-intensity ultrasound: The benefits of ultrasound are its ease-of-use and its ability to precisely\ndeliver energy in opaque and complex media. However, most materials responsive\nto ultrasound show a weak response, requiring the use of high powers, which are\nassociated with undesirable streaming, cavitation, or temperature rise. These\neffects hinder response control and may even cause damage to the medium where\nthe ultrasound is applied. Moreover, materials that are currently in use rely\non all-or-nothing effects, limiting the ability to fine-tune the response of\nthe material on the fly. For these reasons, there is a need for materials that\ncan respond to low intensity ultrasound with programmable responses. Here it is\ndemonstrated that antibubbles are a low-intensity-ultrasound-responsive\nmaterial system that can controllably release a payload using acoustic\npressures in the kPa range. Varying their size and composition tunes the\nrelease pressure, and the response can be switched between a single release and\nstepwise release across multiple ultrasound pulses. Observations using confocal\nand high-speed microscopy revealed different ways that can lead to release.\nThese findings lay the groundwork to design antibubbles that controllably\nrespond to low-intensity ultrasound, opening a wide range of applications\nranging from ultrasound-responsive material systems to carriers for targeted\ndelivery."
    },
    {
        "anchor": "A Tube Model of Rubber Elasticity: Polymer entanglements lead to complicated topological constraints and\ninteractions between neighbouring chains in a dense solution or melt.\nEntanglements can be treated in a mean field approach, within the famous\nreptation model, since they effectively confine each individual chain in a\ntube-like geometry. In polymer networks, due to crosslinks preventing the\nreptation constraint release, entanglements acquire a different topological\nmeaning and have a much stronger effect on the resulting mechanical response.\nWe apply the classical ideas of reptation dynamics to calculate the effective\nrubber-elastic free energy of an entangled rubbery network. We then compare the\nresults with other theoretical approaches and establish a particularly close\nmapping with the hoop-model, with equally good description of experimental\ndata. The present consistent reptation theory allows further development of\ndynamic theory of stress relaxation.",
        "positive": "Crystallisation Instability in Glassforming Mixtures: Crucial to gaining control over crystallisation in multicomponent materials\nor accurately modelling rheological behaviour of magma flows is to understand\nthe mechanisms by which crystal nuclei form. The microscopic nature of such\nnuclei, however, makes this extremely hard in experiments, while computer\nsimulations have hitherto been hampered by their short timescales and small\nsystem sizes due to limited computational power. Here we use highly-efficient\nGPU simulation techniques to access system sizes around 100 times larger than\nprevious studies. This makes it possible to elucidate the nucleation mechanism\nin a well-studied binary glassformer. We discover that the supercooled liquid\nis inherently unstable for system sizes of 10,000 particles and larger. This\neffect is due to compositional fluctuations leading to regions comprised of\nlarge particles only which rapidly nucleate. We argue that this mechanism\nprovides a minimum rate of crystallisation in mixtures in general, and use our\nresults to stabilise a model binary mixture and predict glassforming ability\nfor the CuZr metallic glassformer."
    },
    {
        "anchor": "Stability from activity: Suspensions of actively driven anisotropic objects exhibit distinctively\nnonequilibrium behaviors, and current theories predict that they are incapable\nof sustaining orientational order at high activity. By contrast, here we show\nthat nematic suspensions on a substrate can display order at arbitrarily high\nactivity due to a previously unreported, potentially stabilizing active force.\nThe resulting nonequilibrium ordered phase displays robust giant number\nfluctuations that cannot be suppressed even by an incompressible solvent. Our\nresults apply to virtually all experimental assays used to investigate the\nactive nematic ordering of self-propelled colloids, bacterial suspensions and\nthe cytoskeleton, and have testable implications in interpreting their\nnonequilibrium behaviors",
        "positive": "Bridge Hopping on Conducting Polymers in Solution: Configurational fluctuations of conducting polymers in solution can bring\ninto proximity monomers which are distant from each other along the backbone.\nElectrons can hop between these monomers across the \"bridges\" so formed. We\nshow how this can lead to (i) a collapse transition for metallic polymers, and\n(ii) to the observed dramatic efficiency of acceptor molecules for quenching\nfluorescence in semiconducting polymers."
    },
    {
        "anchor": "The mechanics of human brain organoids: Organoids are prototypes of human organs derived from cultured human stem\ncells. They provide a reliable and accurate experimental model to study the\nphysical mechanisms underlying the early developmental stages of human organs\nmorphogenesis and, in particular, the early morphogenesis of the cortex. Here,\nwe propose a mathematical model to elucidate the role played by two mechanisms\nwhich have been experimentally proven to be crucial in shaping human brain\norganoids: the contraction of the inner core of the organoid and the\nmicrostructural remodeling of the outer cortex. Our results show that both\nmechanisms are crucial for the final shape of the organoid and can explain the\norigin of brain pathologies such as lissencephaly (smooth brain).",
        "positive": "Two-Dimensional Ordering of Bacteriorhodopsins in a Lipid Bilayer and\n  Effects Caused by Repulsive Core between Lipid Molecules on Lateral Depletion\n  Interaction: A Study based on a Thermodynamic Perturbation Theory: Using binary hard disk mixture models, we studied the two-dimensional\nordering of bacteriorhodopsins in a lipid bilayer. The phase diagrams were\ncalculated using the thermodynamic perturbation theory. We examined two types\nof effective interactions to discuss the lateral depletion effects caused by\nrepulsive core interaction between lipid molecules. The results indicate that\nthe core repulsions drastically broaden the coexistence region for the\nfluid--ordered phase."
    },
    {
        "anchor": "Velocity Profiles in Repulsive Athermal Systems under Shear: We conduct molecular dynamics simulations of athermal systems undergoing\nboundary-driven planar shear flow in two and three spatial dimensions. We find\nthat these systems possess nonlinear mean velocity profiles when the velocity\n$u$ of the shearing wall exceeds a critical value $u_c$. Above $u_c$, we also\nshow that the packing fraction and mean-square velocity profiles become\nspatially-dependent with dilation and enhanced velocity fluctuations near the\nmoving boundary. In systems with overdamped dynamics, $u_c$ is only weakly\ndependent on packing fraction $\\phi$. However, in systems with underdamped\ndynamics, $u_c$ is set by the speed of shear waves in the material and tends to\nzero as $\\phi$ approaches $\\phi_c$. In the small damping limit, $\\phi_c$\napproaches values for random close-packing obtained in systems at zero\ntemperature. For underdamped systems with $\\phi<\\phi_c$, $u_c$ is zero and thus\nthey possess nonlinear velocity profiles at any nonzero boundary velocity.",
        "positive": "Optimal run-and-tumble based transportation of a Janus particle with\n  active steering: Even though making artificial micrometric swimmers has been made possible by\nusing various propulsion mechanisms, guiding their motion in the presence of\nthermal fluctuations still remains a great challenge. Such a task is essential\nin biological systems, which present a number of intriguing solutions that are\nrobust against noisy environmental conditions as well as variability in\nindividual genetic makeup. Using synthetic Janus particles driven by an\nelectric field, we present a feedback-based particle guiding method, quite\nanalogous to the \"run-and-tumbling\" behavior of Escherichia coli but with a\ndeterministic steering in the tumbling phase: the particle is set to the \"run\"\nstate when its orientation vector aligns with the target, while the transition\nto the \"steering\" state is triggered when it exceeds a tolerance angle\n{\\alpha}. The active and deterministic reorientation of the particle is\nachieved by a characteristic rotational motion that can be switched on and off\nby modulating the AC frequency of the electric field, first reported in this\nwork. Relying on numerical simulations and analytical results, we show that\nthis feedback algorithm can be optimized by tuning the tolerance angle\n{\\alpha}. The optimal resetting angle depends on signal to noise ratio in the\nsteering state, and it is demonstrated in the experiment. Proposed method is\nsimple and robust for targeting, despite variability in self-propelling speeds\nand angular velocities of individual particles."
    },
    {
        "anchor": "Oil removal from water oil emulsions using magnetic nanocomposite\n  fibrous mats: Herein we present the fabrication of hydrophobic and oleophilic poly(methyl\nmethacrylate) based nanocomposite fibrous mats with magnetic properties, and\ntheir utilization for oil removal from stable water oil emulsions.",
        "positive": "Hybrid Nanocomposites with Tunable Alignment of the Magnetic Nanorod\n  Filler: For many important applications, the performance of polymer-anisotropic\nparticle nanocomposite materials strongly depends on the orientation of the\nnanoparticles. Using the very peculiar magnetic properties of goethite\n({\\alpha}-FeOOH) nanorods, we produced goethite-poly(hydroxyethyl methacrylate)\nnanocomposites in which the alignment direction and the level of orientation of\nthe nanorods could easily be tuned by simply adjusting the intensity of a\nmagnetic field applied during polymerization. Because the particle volume\nfraction was kept low (1-5.5 vol \\%), we used the orientational order induced\nby the field in the isotropic phase rather than the spontaneous orientational\norder of the nematic phase. At the strongest field values (up to 1.5 T), the\nparticles exhibit almost perfect antinematic alignment, as measured by optical\nbirefringence and small-angle X-ray scattering. The results of these two\ntechniques are in remarkably good agreement, validating the use of\nbirefringence measurements for quantifying the degree of orientational order.\nWe also demonstrate that the ordering induced by the field in the isotropic\nsuspension is preserved in the final material after field removal. This work\nillustrates the interest, for such problems, of considering the field-induced\nalignment of anisotropic nanoparticles in the isotropic phase, an approach that\nis effective at low filler content, that avoids the need of controlling the\nnematic texture, and that allows tuning of the orientation level of the\nparticles at will simply by adjusting the field intensity."
    },
    {
        "anchor": "Exactly Solvable Disordered Sphere-Packing Model in Arbitrary-Dimension\n  Euclidean Spaces: We introduce a generalization of the well-known random sequential addition\n(RSA) process for hard spheres in $d$-dimensional Euclidean space\n$\\mathbb{R}^d$. We show that all of the $n$-particle correlation functions of\nthis nonequilibrium model, in a certain limit called the \"ghost\" RSA packing,\ncan be obtained analytically for all allowable densities and in any dimension.\nThis represents the first exactly solvable disordered sphere-packing model in\narbitrary dimension. The fact that the maximal density $\\phi(\\infty)=1/2^d$ of\nthe ghost RSA packing implies that there may be disordered sphere packings in\nsufficiently high $d$ whose density exceeds Minkowski's lower bound for Bravais\nlattices, the dominant asymptotic term of which is $1/2^d$. Indeed, we report\non a conjectural lower bound on the density whose asymptotic behavior is\ncontrolled by $2^{-(0.77865...) d}$, thus providing the putative exponential\nimprovement on Minkowski's 100-year-old bound. Our results suggest that the\ndensest packings in sufficiently high dimensions may be disordered rather than\nperiodic, implying the existence of disordered classical ground states for some\ncontinuous potentials.",
        "positive": "Crater formation during raindrop impact on sand: After a raindrop impacts on a granular bed, a crater is formed as both drop\nand target deform. After an initial, transient, phase in which the maximum\ncrater depth is reached, the crater broadens outwards until a final steady\nshape is attained. By varying the impact velocity of the drop and the packing\ndensity of the bed, we find that avalanches of grains are important in the\nsecond phase and hence, affect the final crater shape. In a previous paper, we\nintroduced an estimate of the impact energy going solely into sand deformation\nand here we show that both the transient and final crater diameter collapse\nwith this quantity for various packing densities. The aspect ratio of the\ntransient crater is however altered by changes in the packing fraction."
    },
    {
        "anchor": "Ring polymers in the melt state: the physics of crumpling: The conformational statistics of ring polymers in melts or dense solutions is\nstrongly affected by their quenched microscopic topological state. The effect\nis particularly strong for non-concatenated unknotted rings, which are known to\ncrumple and segregate and which have been implicated as models for the generic\nbehavior of interphase chromosomes. Here we use a computationally efficient\nmulti-scale approach to show that melts of rings of total contour length $L_r$\ncan be {\\it quantitatively} mapped onto melts of {\\em interacting} lattice\ntrees with gyration radii $\\langle R_g^2(L_r) \\rangle \\propto L_r^{2\\nu}$ and\n$\\nu=0.32\\pm0.01$.",
        "positive": "Colloidal Inclusions in Liquid Crystals: We outline the necessary background to understand the interaction of colloids\nin liquid crystals through boundary conditions and topology."
    },
    {
        "anchor": "Non-equilibrium dynamics of bacterial colonies -- growth, active\n  fluctuations, segregation, adhesion, and invasion: Colonies of bacteria endowed with a pili-based self-propulsion machinery are\nideal models for investigating the structure and dynamics of active\nmany-particle systems. We study Neisseria gonorrhoeae colonies with a\nmolecular-dynamics-based approach. A generic, adaptable simulation method for\nparticle systems with fluctuating bond-like interactions is devised. The\nsimulations are employed to investigate growth of bacterial colonies and the\ndependence of the colony structure on cell-cell interactions. In colonies,\npilus retraction enhances local ordering. For colonies consisting of different\ntypes of cells, the simulations show a segregation depending on the\npili-mediated interactions among different cells. These results agree with\nexperimental observations. Next, we quantify the power-spectral density of\ncolony-shape fluctuations in silico. Simulations predict a strong violation of\nthe equilibrium fluctuation-response relation. Furthermore, we show that active\nforce generation enables colonies to spread on surfaces and to invade narrow\nchannels. The methodology can serve as a foundation for future studies of\nactive many-particle systems at boundaries with complex shape.",
        "positive": "The role of the attractive forces in a supercooled liquid: Molecular Dynamics simulations of crystallization in a supercooled liquid of\nLennard-Jones particles with different range of attractions shows that the\ninclusion of the attractive forces from the first, second and third\ncoordination shell increases the trend to crystallize systematic. The\nbond-order $Q_6$ in the supercooled liquid is heterogeneously distributed with\nclusters of particles with relative high bond-order for a supercooled liquid,\nand a systematic increase of the extent of heterogeneity with increasing range\nof attractions. The onset of crystallization appears in such a cluster, which\ntogether explains the attractive forces influence on crystallization. The mean\nsquare displacement and self-diffusion constant exhibit the same dependence on\nthe range of attractions in the dynamics and shows, that the attractive forces\nand the range of the forces plays an important role for bond-ordering,\ndiffusion and for crystallization."
    },
    {
        "anchor": "Equation of State of Colloidal Membranes: In the presence of a non-adsorbing polymer, monodisperse rod-like colloids\nassemble into one-rod-length thick liquid-like monolayers, called colloidal\nmembranes. The density of the rods within a colloidal membrane is determined by\na balance between the osmotic pressure exerted by the enveloping polymer\nsuspension and the repulsion between the colloidal rods. We developed a\nmicrofluidic device for continuously observing an isolated membrane while\ndynamically controlling the osmotic pressure of the polymer suspension. Using\nthis technology we measured the membrane rod density over a range of osmotic\npressures than is wider that what is accessible in equilibrium samples. With\nincreasing density we observed a first-order phase transition, in which the\nin-plane membrane order transforms from a 2D fluid into a 2D solid. In the\nlimit of low osmotic pressures, we measured the rate at which individual rods\nevaporate from the membrane. The developed microfluidic technique could have\nwide applicability for in situ investigation of various soft materials and how\ntheir properties depend on the solvent composition.",
        "positive": "Nanostructural polymorphism in the low-birefringence chiral phase of an\n  achiral bent-shaped dimer: Polymorphism, the phenomenon that a species can exist in many discrete forms,\nis common in nature, such as hair colors in an animal species, flower colors in\na tree species, and blood types in humans, etc. In materials science, it refers\nto a solid that can exist in multiple forms with different crystalline\nstructures. In the liquid crystals field, however, polymorphism is hard to find\nbecause a discontinuous structural variation is basically impossible because of\ntheir fluid or partially fluid nature. Herein we show that the B4 and DC phases\nthat for many years have been classified as distinctive phases are connected,\nin terms of their nano-architectures, based on the study of a single compound,\na flexible bent-shaped dimer. The surrounding solvent is the key to assisting\nthe dimeric molecules in morphing and adopting different supramolecular\nstructures at the mesoscale. Furthermore, we accidentally find a novel\nnanotube-like structure that has not yet been reported in view of the B4/DC\nphases. Together with the known sponge (DC) and the helical filament (B4)\nstructures, they are just some of the manifestations of the polymorphism in a\nclass of low-birefringence, chiral phase from achiral liquid crystals."
    },
    {
        "anchor": "Activity Mediated Globule to Coil Transition of a Flexible Polymer in\n  Poor Solvent: Understanding the role of self-propulsion on the conformational properties of\nactive filamentous objects has relevance in biology. In this context, we\nconsider a flexible bead-spring model polymer for which along with both\nattractive and repulsive interactions among the non-bonded monomers, activity\nfor each bead works along its intrinsic direction of self-propulsion. We study\nits kinetics in the overdamped limit, following a quench from good to poor\nsolvent condition. We observe that with low activities, though the kinetic\npathways remain similar, the scaling exponent for the relaxation time of\nglobule formation becomes smaller than that for the passive case.\nInterestingly, for higher activities when self-propulsion dominates over\ninteraction energy, the polymer becomes more extended. In its steady state, the\nvariation of the spatial extension of the polymer, measured via its gyration\nradius, shows two completely different scaling regimes: The corresponding Flory\nexponent changes from $1/3$ to $3/5$ similar to a transition of the polymer\nfrom a globular state to a self-avoiding walk. This can be explained by an\ninterplay among three energy scales present in the system, viz., the\n\"ballistic\", thermal, and interaction energy.",
        "positive": "Local structure of percolating gels at very low volume fractions: The formation of colloidal gels is strongly dependent on the volume fraction\nof the system and the strength of the interactions between the colloids. Here\nwe explore very dilute solutions by the means of numerical simulations, and\nshow that, in the absence of hydrodynamic interactions and for sufficiently\nstrong interactions, percolating colloidal gels can be realised at very low\nvalues of the volume fraction. Characterising the structure of the network of\nthe arrested material we find that, when reducing the volume fraction, the gels\nare dominated by low-energy local structures, analogous to the isolated\nclusters of the interaction potential. Changing the strength of the interaction\nallows us to tune the compactness of the gel as characterised by the fractal\ndimension, with low interaction strength favouring more chain-like structures."
    },
    {
        "anchor": "Coupled dynamical phase transitions in driven disk packings: Under the influence of oscillatory shear, a mono-layer of frictional granular\ndisks exhibits two dynamical phase transitions: a transition from an initially\ndisordered state to an ordered crystalline state, and a dynamic\nactive-absorbing phase transition. Although there is no reason, {\\it a-priori},\nfor these to be at the same critical point, they are. The transitions may also\nbe characterized by the disk trajectories, which are non-trivial loops breaking\ntime-reversal invariance.",
        "positive": "Complex Memory Formation in Frictional Granular Media: Using numerical simulations it is shown that a jammed, random pack of soft\nfrictional grains can store an arbitrary waveform that is applied as a small\ntime-dependent shear while the system is slowly compressed. When the system is\ndecompressed at a later time, an approximation of the input waveform is\nrecalled in time-reversed order as shear stresses on the system boundaries.\nThis effect depends on friction between the grains, and is independent of some\naspects of the friction model. This type of memory could potentially be\nobservable in other types of random media that form internal contacts when\ncompressed."
    },
    {
        "anchor": "Tilting behavior of lamellar ice tip during unidirectional freezing of\n  aqueous solutions: Freezing of ice has been largely reported from many aspects, especially its\ncomplex pattern formation. Ice grown from liquid phase is usually\ncharacteristic of lamellar morphology which plays a significant role in various\ndomains. However, tilted growth of ice via transition from coplanar to\nnon-coplanar growth in directional solidification has been paid little\nattention in previous studies and there is misleading explanation of the\nformation of tilted lamellar ice. Here, we in-situ investigated the variations\nof tilting behavior of lamellar ice tip under different conditions within a\nsingle ice crystal with manipulated orientation via unidirectional freezing of\naqueous solutions. It is found that tilted growth of ice tips is sensitive to\npulling velocity and solute type. These experimental results reveal intrinsic\ntilted growth behavior of lamellar ice and enrich our understanding in pattern\nformation of ice.",
        "positive": "Review: Simulational Tests of the Rouse Model: The file is a Chapter from my review volume \"Polymer Physics: Phenomenology\nof Polymeric Fluid Simulations\". The chapter treats literature tests of the\nRouse model, which is widely invoked as a description of polymer motion in\nmelts. In summary: The literature conclusively demonstrates that the Rouse\nmodel does not describe polymer motion in melts. Simulations find that the\ntemporal autocorrelation function of a single Rouse amplitude is a stretched\nexponential in time, not the pure exponential predicted by the Rouse model.\nAlso, the mean-square amplitude of the Rouse modes <(X_p (0) X_p (0) > deviates\nfrom the model's prediction, at least for p > 3. Furthermore, the relaxation\ntime of <(X_p (0) X_p (t) > depends on p, but not as predicted by the Rouse\nmodel. According to the Rouse model, bead displacements are driven by\nindependent Gaussian random processes. Accordingly, the intermediate structure\nfactor g(q,t) is predicted to be accurately described by the Gaussian\napproximation. Doob's theorem then guarantees that g(q,t) decays as a single\nexponential in time. Simulations show that these predictions of the Rouse model\nare incorrect."
    },
    {
        "anchor": "Single Molecule Michaelis-Menten Equation beyond Quasi-Static Disorder: The classic Michaelis-Menten equation describes the catalytic activities for\nensembles of enzyme molecules very well. But recent single-molecule experiment\nshowed that the waiting time distribution and other properties of single enzyme\nmolecule are not consistent with the prediction based on the viewpoint of\nensemble. It has been contributed to the slow inner conformational changes of\nsingle enzyme in the catalytic processes. In this work we study the general\ndynamics of single enzyme in the presence of dynamic disorder. We find that at\ntwo limiting cases, the slow reaction and nondiffusion limits, Michaelis-Menten\nequation exactly holds although the waiting time distribution has a\nmultiexponential decay behaviors in the nondiffusion limit.Particularly, the\nclassic Michaelis-Menten equation still is an excellent approximation other\nthan the two limits.",
        "positive": "The Isotropic-Nematic Interface with an Oblique Anchoring Condition: We present numerical and analytic results for uniaxial and biaxial order at\nthe isotropic-nematic interface within Ginzburg-Landau-de Gennes theory. We\nstudy the case where an oblique anchoring condition is imposed asymptotically\non the nematic side of the interface, reproducing results of previous work when\nthis condition reduces to planar or homoeotropic anchoring. We construct\nphysically motivated and computationally flexible variational profiles for\nuniaxial and biaxial order, comparing our variational results to numerical\nresults obtained from a minimization of the Ginzburg-Landau-de Gennes free\nenergy. While spatial variations of the scalar uniaxial and biaxial order\nparameters are confined to the neighbourhood of the interface, nematic\nelasticity requires that the director orientation interpolate linearly between\neither planar or homoeotropic anchoring at the location of the interface and\nthe imposed boundary condition at infinity. The selection of planar or\nhomoeotropic anchoring at the interface is governed by the sign of the\nGinzburg-Landau-de Gennes elastic coefficient L_2. Our variational calculations\nare in close agreement with our numerics and agree qualitatively with results\nfrom density functional theory and molecular simulations."
    },
    {
        "anchor": "Nanocellulose Fragmentation Mechanisms and Inversion of Chirality from\n  the Single Particle to the Cholesteric Phase: Understanding how nanostructure and nanomechanics influence physical material\nproperties on the micro- and macroscale is an essential goal in soft condensed\nmatter research. Mechanisms governing fragmentation and chirality inversion of\nfilamentous colloids are of specific interest because of their critical role in\nload-bearing and self-organizing functionalities of soft nanomaterials. Here we\nprovide a fundamental insight into the self-organization across several length\nscales of nanocellulose, an important bio-colloid system with wide-ranging\napplications as structural, insulating and functional material. Through a\ncombined microscopic and statistical analysis of nanocellulose fibrils at the\nsingle particle level, we show how mechanically and chemically induced\nfragmentation proceed in this system. Moreover, by studying the bottom-up\nself-assembly of fragmented carboxylated cellulose nanofibrils into cholesteric\nliquid crystals, we show via direct microscopic observations, that the\nchirality is inverted from right-handed at the nanofibril level to left-handed\nat the level of the liquid crystal phase. These results improve our fundamental\nunderstanding of nanocellulose and provide an important rationale for their\napplication in colloidal systems, liquid crystals and nanomaterials.",
        "positive": "Nanoscale heterogeneous phase separation kinetics in binary mixtures:\n  Multistage dynamics: In order to find a measure of the dynamical features of phase separation\nkinetics during spinodal decomposition of a liquid binary mixture (like water\nand cyclohexane , water and 2,6 lutidiene or methanol and cyclohexane), we\nstudy both the initial fast exponential-like growth (the Cahn-Hilliard regime)\nand the subsequent cross-over to a much slower, non-exponential long time\ngrowth (the so-called scaling regime), by atomistic molecular dynamics (MD)\nsimulation of a structure breaking binary liquid mixture. In particular, we\ncombine our MD simulations with a coarse grained multi scale modelling (CGMSM)\ncapable of capturing both length and time scales of phase separation kinetics\nwithin simulation box. The system is quenched from a higher temperature to two\nlower temperatures well below the coexistence temperature of the phase diagram.\nWe observe a multiscale phase separation dynamics. Initially the growth is\nexponential up to a regime of 80-100ps having strong dependence over quench\ndepth. Subsequently a cross-over regime appears where the dynamics slows down\nconsiderably due to coarsening through a power law phase. For deeper quench\npower law growth dominates over the initial exponential and the cross-over\nbecomes transient. We find that for the present parameter values for the binary\nmixture, the initial rapid growth of structure formation is practically over\nwithin 200 ps which is followed by slow structural coarsening. When scaled by\nthe respective viscosities, this time translates to 50-200 ns for\nwater-lutidine binary mixture. The last part of dynamics may extend into ms.\nThe dynamics of phase separation is slowest in regions that have equitable\ndistribution of the two species, and one can observe the signatures of \"up-hill\ndiffusion\" that is a trade mark of spinodal decomposition."
    },
    {
        "anchor": "Dynamics of Ion Transport in Ionic Liquids: A gap in understanding the link between continuum theories of ion transport\nin ionic liquids and the underlying microscopic dynamics has hindered the\ndevelopment of frameworks for transport phenomena in these concentrated\nelectrolytes. Here, we construct a continuum theory for ion transport in ionic\nliquids by coarse graining a simple exclusion process of interacting particles\non a lattice. The resulting dynamical equations can be written as a gradient\nflow with a mobility matrix that vanishes at high densities. This form of the\nmobility matrix gives rise to a charging behaviour that is different to the one\nknown for electrolytic solutions, but which agrees qualitatively with the\nphenomenology observed in experiments and simulations.",
        "positive": "Dynamical Ordering and Directional Locking For Particles Moving Over\n  Quasicrystalline Substrates: We use molecular dynamics simulations to study the driven phases of particles\nsuch as vortices or colloids moving over a decagonal quasiperiodic substrate.\nIn the regime where the pinned states have quasicrystalline ordering, the\ndriven phases can order into moving square or smectic states, or into states\nwith aligned rows of both square and triangular tiling which we term\ndynamically induced Archimedean-like tiling. We show that when the angle of the\ndrive is varied with respect to the substrate, directional locking effects\noccur where the particle motion locks to certain angles. It is at these locking\nangles that the dynamically induced Archimedean tiling appears. We also\ndemonstrate that the different dynamical orderings and locking phases show\npronounced changes as a function of filling fraction."
    },
    {
        "anchor": "Accuracy of the blob model for single flexible polymers inside nanoslits\n  that are a few monomer sizes wide: The de Gennes' blob model is extensively used in different problems of\npolymer physics. This model is theoretically applicable when the number of\nmonomers inside each blob is large enough. For confined flexible polymers, this\nrequires the confining geometry to be much larger than the monomer size. In\nthis manuscript, the opposite limit of polymer in nano-slits with one to\nseveral monomers width is studied, using molecular dynamics simulations.\nExtension of the polymer inside nanoslits, confinement force on the plates, and\nthe effective spring constant of the confined polymer are investigated. Despite\nof the theoretical limitations of the blob model, the simulation results are\nexplained with the blob model very well. The agreement is observed for the\nstatic properties and the dynamic spring constant of the polymer. A theoretical\ndescription of the conditions under which the dynamic spring constant of the\npolymer is independent of the small number of monomers inside blobs is given.\nOur results on the limit of applicability of the blob model can be useful in\nthe design of nanotechnology devices.",
        "positive": "Rheology of bacterial suspensions under confinement: As a paradigmatic model of active fluids, bacterial suspensions show\nintriguing rheological responses drastically different from their counterpart\ncolloidal suspensions. Although the flow of bulk bacterial suspensions has been\nextensively studied, the rheology of bacterial suspensions under confinement\nhas not been experimentally explored. Here, using a microfluidic viscometer, we\nsystematically measure the rheology of dilute E. coli suspensions under\ndifferent degrees of confinement. Our study reveals a strong confinement\neffect: the viscosity of bacterial suspensions decreases substantially when the\nconfinement scale is comparable or smaller than the run length of bacteria.\nMoreover, we also investigate the microscopic dynamics of bacterial suspensions\nincluding velocity profiles, bacterial density distributions and single\nbacterial dynamics in shear flows. These measurements allow us to construct a\nsimple heuristic model based on the boundary layer of upstream swimming\nbacteria near confining walls, which qualitatively explains our experimental\nobservations. Our study sheds light on the influence of the boundary layer of\ncollective bacterial motions on the flow of confined bacterial suspensions. Our\nresults provide a benchmark for testing different rheological models of active\nfluids and are useful for understanding the transport of microorganisms in\nconfined geometries."
    },
    {
        "anchor": "(Quantum) Chaos in BECs: I consider general connections between chaotic and quantum chaotics dynamics\nin single particles, and the effect of adding comparable ``chaos-inducing''\npotentials to a Bose-condensed system, considering in particular concepts of\nintegrability and the effect of particle loss from the condensate mode.",
        "positive": "Packings of frictionless spherocylinders: We present simulation results on the properties of packings of frictionless\nspherocylindrical particles. Starting from a random distribution of particles\nin space, a packing is produced by minimizing the potential energy of\ninter-particle contacts until a force-equilibrated state is reached. For\ndifferent particle aspect ratios $\\alpha=10\\ldots 40$, we calculate contacts\n$z$, pressure as well as bulk and shear modulus. Most important is the fraction\n$f_0$ of spherocylinders with contacts at both ends as it governs the jamming\nthreshold $z_c(f_0)=8+2f_0$. These results highlight the important role of the\naxial \"sliding\" degree of freedom of a spherocylinder, which is a zero-energy\nmode but only if no end-contacts are present."
    },
    {
        "anchor": "A discrete model for layered growth: In this work we present a discrete model that captures the fundamental\nproperties of additively manufactured solids in a minimal setting. The model is\nbased on simplified kinematics and allows for the onset of incompatible\ndeformations between discrete layers of an additively manufactured stack.\nThanks to the discrete nature of the model, we obtain an averaged formulation\nof mechanical equilibrium for the growing stack, leading to closed-form\nsolutions that are both analytically simple and physically transparent. In\nparticular, we are able to explain the origin of residual stresses by the\naccumulation of incompatible deformations between adjacent layers. At the same\ntime, we are able to formulate the technologically relevant inverse problem\nthat provides the deposition protocol required to produce a desired state of\ninternal stress in the manufactured stack. Another important aspect analyzed in\nthe work is the role played by an ideal ``glue'' between the layers, whose\npresence is fundamental to prevent their sliding and whose mechanical behavior\ncan quantitatively influence the final stress distribution in the stack.\nAlthough the model is an elementary approximation of additive manufacturing,\nits simplicity makes it possible to highlight how the controls exerted during\ndeposition will have qualitative or quantitative effects on the final stress\nstate of the stack. This understanding is crucial in shedding light on the\ncomplex mechanical behavior of additive manufactured solids.",
        "positive": "Equilibrium microstructures of diblock copolymers under 3D confinement: We investigate equilibrium microstructures exhibited by diblock copolymers in\nconfined 3D geometries. We perform Self-Consistent Field Theory (SCFT)\nsimulations using a finite-element based computational framework (Ackerman et\nal. 2017), that provides the flexibility to compute equilibrium structures\nunder arbitrary geometries. We consider a sequence of 3D geometries\n(tetrahedron to sphere) that have the same volume but exhibit varying\ncurvature. This allows us to study the interplay between edge and curvature\neffects of the 3D geometries on the equilibrium microstructures. We observe\nthat beyond a length scale, the equilibrium structure changes from an\ninterconnected network to a multi-layered concentric shell as the curvature of\nthe 3D geometry is reduced. However, below this length scale the equilibrium\nstructure remains a multi-layered concentric shell independent of curvature. We\nadditionally explore variations in the equilibrium microstructures at a few\ndiscrete volume fractions. This study provides insight into possible frustrated\nphases that can arise in AB diblock systems while varying the shape of\nconfinement geometry."
    },
    {
        "anchor": "Long-wavelength fluctuations and dimensionality crossover in confined\n  liquids: The phase behavior of liquids confined in a slit geometry does not reveal a\ncrossover from a three to a two-dimensional behavior as the gap size decreases.\nIndeed, the prototypical two-dimensional hexatic phase only occurs in liquids\nconfined to a monolayer. Here, we demonstrate that the dimensionality crossover\nis apparent in the lateral size dependence of the relaxation dynamics of\nconfined liquids, developing a Debye model for the density of vibrational\nstates of confined systems and performing extensive numerical simulations. In\nconfined systems, Mermin-Wagner fluctuations enhance the amplitude of\nvibrational motion or Debye-Waller factor by a quantity scaling as the inverse\ngap width and proportional to the logarithm of the aspect ratio, as a clear\nsignature of a two-dimensional behaviour. As the temperature or lateral system\nsize increases, the crossover to a size-independent relaxation dynamics occurs\nwhen structural relaxation takes place before the vibrational modes with the\nlongest wavelength develop.",
        "positive": "Isostaticity of Constraints in Jammed Systems of Soft Frictionless\n  Platonic Solids: The average number of constraints per particle $< C_{total} >$ in\nmechanically stable systems of Platonic solids (except cubes) approaches the\nisostatic limit at the jamming point ($< C_{total} > \\rightarrow 12$), though\naverage number of contacts are hypostatic. By introducing angular alignment\nmetrics to classify the degree of constraint imposed by each contact,\nconstraints are shown to arise as a direct result of local orientational order\nreflected in edge-face and face-face alignment angle distributions. With\napproximately one face-face contact per particle at jamming chain-like\nface-face clusters with finite extent form in these systems."
    },
    {
        "anchor": "Lifetime of vertical giant soap films: role of the relative humidity and\n  film dimensions: We consider the lifetime of rectangular vertical soap films and we explore\nthe influence of relative humidity and both dimensions on the stability of\nlarge soap films, reaching heights of up to 1.2 m. Using an automated rupture\ndetection system, we achieve a robust statistical measurement of their\nlifetimes and we also measure the film thinning dynamics. We demonstrate that\ndrainage has a negligible impact on the film stability as opposed to\nevaporation. To do so, we compare the measured lifetimes with predictions from\nthe Boulogne \\& Dollet model \\cite{BoulogneDollet2018}, originally designed to\ndescribe the convective evaporation of hydrogels. Interestingly, we show that\nthis model can predict a maximum film lifetime for all sizes.",
        "positive": "Drastic slowdown of shear waves in unjammed granular suspensions: We present an experimental investigation of shear elastic wave propagation\nalong the surface of a dense granular suspension. Using an ultrafast ultrasound\nscanner, we monitor the softening of the shear wave velocity inside the\noptically opaque medium as the driving amplitude increases. For such nonlinear\nbehavior two regimes are found: in the first regime, we observe a significant\nshear modulus weakening, but without visible grain rearrangements. In the\nsecond regime, there is a clear grain rearrangement accompanied by a modulus\ndecrease up to 88%. A friction model is proposed to describe the interplay\nbetween nonlinear elasticity and plasticity, which highlights the crucial\neffect of contact slipping before contact breaking. Investigation of these\nnonlinear shear waves may bridge the gap between two disjoint approaches for\ndescribing the dynamics near unjamming: linear elastic soft modes and nonlinear\ncollisional shock."
    },
    {
        "anchor": "Experimental observation of gapped shear waves and liquid-like to\n  gas-like dynamical crossover in active granular matter: Unlike crystalline solids, liquids do not exhibit long-range order. Their\natoms undergo frequent structural rearrangements, resulting in the\nlong-wavelength dynamics of shear fluctuations in liquids being diffusive,\nrather than propagating waves, as observed in crystals. When considering\nshorter time and length scales, molecular dynamics simulations and theoretical\npropositions suggest that collective shear excitations in liquids display a gap\nin wave-vector space, referred to as the $k$-gap. Above this gap, solid-like\ntransverse waves re-emerge. However, direct experimental verification of this\nphenomenon in classical liquids remains elusive, with the only documented\nevidence from studies in two-dimensional dusty plasmas. Active granular systems\nprovide a novel platform for exploring the emergence of collective dynamics and\nshowcasing a rich interplay of complex phases and phenomena. Our study focuses\non bi-disperse active Brownian vibrators. Through measurements of the pair\ncorrelation functions, mean square displacements, velocity auto-correlation\nfunctions, vibrational density of states, and a detailed analysis of\nmicroscopic atomic motion, we demonstrate that this active system exhibits both\ngas-like and liquid-like phases, depending on the packing fraction, despite\npure hard-disk-like repulsive interactions. Notably, within the granular\nliquid-like phase, we experimentally validate the existence of a $k$-gap in the\ndispersion of transverse excitations. This gap becomes more significant with a\ndecrease in packing fraction and disappears into the gas phase, aligning with\ntheoretical expectations. Our results offer a direct experimental confirmation\nof the $k$-gap phenomenon, extending its relevance beyond classical thermal\nliquids to active granular systems, and reveal the existence of intriguing\nsimilarities between the physics of active granular matter and supercritical\nfluids.",
        "positive": "Novel Shear Banding Phenomenon Probes Soap Film Friction: We have generated a novel form of shear banding in a 2D foam and measured the\nrelative magnitude of drag forces on soap films at different lubrication\nlayers. We injected air part way along a flowing bubble field in a narrow\nHele-Shaw cell. The injected air inflates bubbles as they flow by, and these\nbubbles form a shear band down the middle of the Hele-Shaw cell. This channel\nappears to select a height that minimizes the total dissipation. Fitting data\nto a simple theoretical model, we show that the drag force on a soap film in\ncontact with the wetting layer on a plate of glass is two orders of magnitude\nlarger than the drag on a soap film in contact with another free soap film."
    },
    {
        "anchor": "Dynamic, viscoelasticity-driven shape change of elastomer bilayers: Thin bilayers made of elastic sheets with different strain recoveries can be\nused for dynamic shape morphing through ambient stimuli, such as temperature,\nmass diffusion, and light. As a fundamentally different approach to designing\ntemporal shape change, constituent polymer molecular features (rather than\nexternal fields) are leveraged, specifically the viscoelasticity of gelatin\nbilayers, to achieve dynamic three-dimensional (3D) curls and helical twists.\nAfter stretching and releasing, the acquired 3D shape recovers its original\nflat shape on a timescale originating from the polymer viscoelasticity. The\nbilayer time-dependent curvature can be accurately predicted from hyperelastic\nand viscoelastic functions using finite element analysis (FEA). FEA reveals the\nnonlinear shape dynamics in space and time in quantitative agreement with\nexperiments. The findings present a new frontier in dynamic biomimetic\nshape-morphing by exploiting intrinsic material properties in contrast with\nstate-of-the-art methods relying on external field variations, moving one step\ncloser to acquiring autonomous shape-shifting capabilities of biological\nsystems.",
        "positive": "Dynamics of laser-induced electroconvection pulses: We first report that, for planar nematic MBBA, the electroconvection\nthreshold voltage has a nonmonotonic temperature dependence, with a\nwell-defined minimum, and a slope of about 0.12 V/degree near room temperature.\nMotivated by this observation, we have designed an experiment in which a weak\ncontinuous-wave absorbed laser beam with a diameter comparable to the pattern\nwavelength generates a locally supercritical region, or pulse, in dye-doped\nMBBA. Working 10-20% below the laser-free threshold voltage, we observe a\nsteady-state pulse shaped as an ellipse with the semimajor axis oriented\nparallel to the nematic director, with a typical size of several wavelengths.\nThe pulse is robust, persisting even when spatially extended rolls develop in\nthe surrounding region, and displays rolls that counterpropagate along the\ndirector at frequencies of tenths of Hz, with the rolls on the left (right)\nside of the ellipse moving to the right (left). Systematic measurements of the\nsample-voltage dependence of the pulse amplitude, spatial extent, and frequency\nshow a saturation or decrease when the control parameter (evaluated at the\ncenter of the pulse) approaches ~ 0.3. We propose that the model for these\npulses should be based on the theory of control-parameter ramps, supplemented\nwith new terms to account for the advection of heat away from the pulse when\nthe surrounding state becomes linearly unstable. The advection creates a\nnegative feedback between the pulse size and the efficiency of heat transport,\nwhich we argue is responsible for the attenuation of the pulse at larger\ncontrol-parameter values."
    },
    {
        "anchor": "Roughness-Induced Wetting: We investigate theoretically the possibility of a wetting transition induced\nby geometric roughness of a solid substrate for the case where the flat\nsubstrate does not show a wetting layer. Our approach makes use of a novel\nclosed-form expression which relates the interaction between two sinusoidally\nmodulated interfaces to the interaction between two flat interfaces. Within the\nharmonic approximation, we find that roughness-induced wetting is indeed\npossible if the substrate roughness, quantified by the substrate surface area,\nexceeds a certain threshold. In addition, the molecular interactions between\nthe substrate and the wetting substance have to satisfy several conditions.\nThese results are expressed in terms of a lower bound on the wetting potential\nfor a flat substrate in order for roughness-induced wetting to occur. This\nlower bound has the following properties: A minimum is present at zero or very\nsmall separation between the two interfaces, as characteristic for the\nnon-wetting situation in the flat case. Most importantly, the wetting potential\nneeds to have a pronounced maximum at a separation comparable to the amplitude\nof the substrate roughness. These findings are in agreement with the\nexperimental observation of roughness-induced surface premelting at a glass-ice\ninterface as well as the calculation of the dispersion interaction for the\ncorresponding glass-water-ice system.",
        "positive": "Two-dimensional crystals on adhesive substrates subjected to uniform\n  transverse pressure: In this work we consider bubbles that can form spontaneously when a\ntwo-dimensional (2D) crystal is transferred to a substrate with gases or\nliquids trapped at the crystal-substrate interface. The underlying mechanics\nmay be described by a thin sheet on an adhesive substrate with the trapped\nfluid applying uniform transverse pressure. What makes this apparently simple\nproblem complex is the rich interplay among geometry, interface, elasticity and\ninstability. Particularly, extensive small-scale experiments have shown that\nthe 2D crystal surrounding a bubble can adhere to and, meanwhile, slide on the\nsubstrate. The radially inward sliding causes hoop compression to the 2D\ncrystal which may exploit wrinkling instabilities to relax or partially relax\nthe compression. We present a theoretical model to understand the complex\nbehaviors of even a linearly elastic 2D crystal due to the combination of\nnonlinear geometry, adhesion, sliding, and wrinkling in bubble systems. We show\nthat this understanding not only successfully predicts the geometry of a\nspontaneous bubble but also reveals the strain-coupled physics of 2D crystals,\ne.g., the pseudomagnetic fields in graphene bubbles."
    },
    {
        "anchor": "Sticky-sphere clusters: Nano- and microscale particles, such as colloids, commonly interact over\nranges much shorter than their diameters, so it is natural to treat them as\n\"sticky,\" interacting only when they touch exactly. The lowest-energy states,\nfree energies, and dynamics of a collection of $n$ particles can be calculated\nin the sticky limit of a deep, narrow interaction potential. This article\nsurveys the theory of the sticky limit, explains the correspondence between\ntheory and experiments on colloidal clusters, and outlines areas where the\nsticky limit may bring new insight.",
        "positive": "Viscous resuspension of non-Brownian particles: determination of the\n  concentration profiles and particle normal stresses: We perform local measurements of both the shear rate and the particle\nfraction to study viscous resuspension in non-Brownian suspensions. A\nsuspension of PMMA spherical particles dispersed in a lighter Newtonian fluid\n(Triton X100) is sheared in a vertical Couette cell. The vertical profiles of\nthe particle volume fraction are measured for Shields numbers ranging from 10\n--3 to 1, and the variation in the particle normal stress in the vorticity\ndirection of the particle fraction is deduced."
    },
    {
        "anchor": "Wave propagation through an elastically-asymmetric architected material: A one-dimensional wave propagation through elastically asymmetric media is\ninvestigated. A class of metamaterials possessing an arbitrary elastic\nasymmetry is proposed. This asymmetry results in different wave speeds of\ntensile and compressive components of elastic waves. The faster component can\novertake the slower one resulting in their dissipative annihilation through\nenergy cascades. Efficient absorbing assemblies are presented and analysed\nnumerically. The length of the asymmetric part needed to damp a harmonic signal\nis determined analytically and validated numerically. Transmission properties\nfor random self-affine wave-packets are studied: a universal scaling for the\ntransmission factor variation with the length of the asymmetric part was\nestablished.",
        "positive": "Drop impact dynamics on slippery liquid-infused porous surfaces:\n  influence of oil thickness: Slippery liquid-infused porous surfaces (SLIPS) are porous nanostructures\nimpregnated with a low surface tension lubricant. They have recently shown\ngreat promise in various applications that require non-wettable\nsuperhydrophobic surfaces. In this paper, we investigate experimentally the\ninfluence of the oil thickness on the wetting properties and drop impact\ndynamics of new SLIPS. By tuning the thickness of the oil layer deposited\nthrough spin-coating, we show that a sufficiently thick layer of oil is\nnecessary to avoid dewetting spots on the porous nanostructure and thus\nincreasing the homogeneity of the liquid distribution. Drop impact on these\nsurfaces is investigated with a particular emphasis on the spreading and\nrebound dynamics when varying the oil thickness and the Weber number."
    },
    {
        "anchor": "A twist-grain boundary (TGB) phase in aqueous solutions of the DNA\n  tetramer GTAC: We report the observation of a Twist Grain Boundary (TGB) phase of DNA, a\nstriking motif of three dimensional (3D) equilibrium self-assembly of the DNA\ntetramer 5'-GTAC-3', a base sequence that is self-complimentary, pairing to\nform 4-base long, blunt-end Watson/Crick (WC) duplexes. Hydrophobic blunt ends\nand liquid crystal ordering enable these short duplexes to aggregate into\nlong-DNA-like columns, even though the double helix has a break every 4 bases.\nA further step assembles these columns into monolayer sheets in which the\ncolumns are mutually parallel, and, finally, these sheets stack into lamellar\narrays in which the column axis of each layer rotates in helical fashion,\nthrough a 60 degree angle with each passage to the next layer. This\nreorientation in a left-handed TGB helix enables each 2nm diameter WC column to\nbe parallel to, and to partially enter, the major grooves of its neighbors.",
        "positive": "The shape of a flexible polymer in a cylindrical pore: We calculate the mean end-to-end distance ($R$) of a self-avoiding polymer\nencapsulated in an infinitely long cylinder with radius $D$. A self-consistent\nperturbation theory is used to calculate $R$ as a function of $D$ for\nimpenetrable hard walls and soft walls. In both cases, $R$ obeys the predicted\nscaling behavior in the limit of large and small $D$. The crossover from the\nthree dimensional behavior ($D\\to\\infty$) to the fully stretched one\ndimensional case ($D\\to 0$) is non-monotonic. The minimum value of $R$ is found\nat $D\\sim 0.46 R_F$, where $R_F$ is the Flory radius of $R$ at $D \\to \\infty$.\nThe results for soft walls map onto the hard wall case with a larger cylinder\nradius."
    },
    {
        "anchor": "Collective Motion in Active Materials: Model Experiments: In these lecture notes from the Les Houches School, we discuss collective\nmotion in model experiments of active systems. We specifically discuss walking\ngrains and colloidal rollers experiments. In both cases, we focus on the\ntheoretical tools one can use to relate the knowledge of the dynamics at the\nparticle scale to the large scale physics.",
        "positive": "Non-Conventional Structural Phase Transitions and Amphiphobic Matter: The aim of this paper is two-fold. First, via a phenomenological\nconsideration I show that, equally with the conventional phases (body-centred\ncubic, hexagonal planar and lamellar), such non-conventional phases as simple\ncubic, face-centered cubic, well known double gyroid as well as some other\nphases could be stable in a vicinity of the critical point in the systems\nundergoing the order-disorder and order-order transition. A general phase\ndiagram indicating the strength of so-called angle dependence of the forth\nvertex necessary for existence of these non-conventional phases is presented.\nNext, I demonstrate via a direct Leibler-like microscopic consideration of the\nternary ABC block and graft copolymers that these real systems do reveal these\nnonconventional phases even close to the critical point. In particular, the\nternary ABC block copolymers with a long middle block non-selective with\nrespect to both side blocks are especially inclined to form the gyroid phase. A\nnew cubic non-centrosymmetric phase and some other cubic phases are also first\npredicted to exist as the most stable low temperature phase instead of the\nlamellar one. Such a phase behavior is suggested to be common for a new class\nof materials we propose to call amphiphobic since their (macro)molecules\nconsist al least of three mutually incompatible types of monomers."
    },
    {
        "anchor": "Liquid crystal films on curved surfaces: An entropic sampling study: The confining effect of a spherical substrate inducing anchoring (normal to\nthe surface) of rod-like liquid crystal molecules contained in a thin film\nspread over it has been investigated with regard to possible changes in the\nnature of the isotropic-to-nematic phase transition as the sample is cooled.\nThe focus of these Monte Carlo simulations is to study the competing effects of\nthe homeotropic anchoring due to the surface inducing orientational ordering in\nthe radial direction and the inherent uniaxial order promoted by the\nintermolecular interactions. By adopting entropic sampling procedure, we could\ninvestigate this transition with a high temperature precision, and we studied\nthe effect of the surface anchoring strength on the phase diagram for a\nspecifically chosen geometry. We find that there is a threshold anchoring\nstrength of the surface below which uniaxial nematic phase results, and above\nwhich the isotropic fluid cools to a radially ordered nematic phase, besides of\ncourse expected changes in the phase transition temperature with the anchoring\nstrength. In the vicinity of the threshold anchoring strength we observe a\nbistable region between these two structures, clearly brought out by the\ncharacteristics of the corresponding microstates constituting the entropic\nensemble.",
        "positive": "Sorption and spatial distribution of protein globules in charged\n  hydrogel particles: We have theoretically studied the uptake of a non-uniformly charged\nbiomolecule, suitable to represent a globular protein or a drug, by a charged\nhydrogel carrier in the presence of a 1:1 electrolyte. Based on the analysis of\na physical interaction Hamiltonian including monopolar, dipolar and Born\n(self-energy) contributions derived from linear electrostatic theory of the\nunperturbed homogeneous hydrogel, we have identified five different sorption\nstates of the system, from complete repulsion of the molecule to its full\nsorption deep inside the hydrogel, passing through meta- and stable surface\nadsorption states. The results are summarized in state diagrams that also\nexplore the effects of varying the electrolyte concentration, the sign of the\nnet electric charge of the biomolecule, and the role of including\nexcluded-volume (steric) or hydrophobic biomolecule-hydrogel interactions. We\nshow that the dipole moment of the biomolecule is a key parameter controlling\nthe spatial distribution of the globules. In particular, biomolecules with a\nlarge dipole moment tend to be adsorbed at the external surface of the\nhydrogel, even if like-charged, whereas uniformly charged biomolecules tend to\npartition towards the internal core of an oppositely-charged hydrogel.\nHydrophobic attraction shifts the states towards internal sorption of the\nbiomolecule, whereas steric repulsion promotes surface adsorption for\noppositely-charged biomolecules, or the total exclusion for likely-charged\nones. Our results establish a guidance for the spatial partitioning of proteins\nand drugs in hydrogel carriers, tuneable by hydrogel charge, pH and salt\nconcentration."
    },
    {
        "anchor": "Self-assembly of polymeric particles in Poiseuille flow: A hybrid\n  Lattice Boltzmann / External Potential Dynamics simulation study: We present a hybrid simulation method which allows one to study the dynamical\nevolution of self-assembling (co)polymer solutions in the presence of\nhydrodynamic interactions. The method combines an established dynamic density\nfunctional theory for polymers that accounts for the nonlocal character of\nchain dynamics at the level of the Rouse model, the external potential dynamics\n(EPD) model, with an established Navier-Stokes solver, the Lattice Boltzmann\n(LB) method. We apply the method to study the self-assembly of nanoparticles\nand vesicles in two-dimensional copolymer solutions in a typical microchannel\nPoiseuille flow profile. The simulations start from fully mixed systems which\nare suddenly quenched below the spinodal line. In order to isolate effects\ncaused by walls, we use a reverse Poiseuille flow geometry with periodic\nboundary conditions. We identify three stages of self assembly, i.e., initial\nspinodal decomposition, particle nucleation, and particle growth (ripening). We\nfind that (i) In the presence of shear, the nucleation of droplets is delayed\nby an amount roughly proportional to the shear rate, (ii) Shear flow greatly\nincreases the rates of particle fusions, (iii) in later stages of\nself-assembly, stronger shear flows may induce irreversible shape\ntransformation {\\em via} finger formation, in particular in vesicle systems.\nThe combination of these effects lead to an accumulation of particles close to\nthe center of the Poiseuille flow profile, and the polymeric matter has a\ndouble peak distribution centered around the flow maximum.",
        "positive": "Fluidification of entanglements by a DNA bending protein: In spite of the nanoscale and single-molecule insights into how nucleoid\nassociated proteins (NAPs) interact with DNA, their role in modulating the\nmesoscale viscoelasticity of the entangled genome in vivo has been overlooked\nso far. By combining microrheology and molecular dynamics simulation we find\nthat the important NAP called Integration Host Factor (IHF) lowers the\nviscosity of entangled $\\lambda$DNA 20-fold at physiological concentrations and\nstoichiometries. We argue that IHF may act as a \"genomic fluidiser\", reducing\nthe effective viscosity of the nucleoid $\\sim$200-fold. Our results suggest a\npreviously unappreciated key role of IHF in regulating DNA dynamics and\nre-organisation in vivo"
    },
    {
        "anchor": "Moving Contact Lines: Linking Molecular Dynamics and Continuum-Scale\n  Modeling: Despite decades of research, the modeling of moving contact lines has\nremained a formidable challenge in fluid dynamics whose resolution will impact\nnumerous industrial, biological, and daily life applications. On the one hand,\nmolecular dynamics (MD) simulation has the ability to provide unique insight\ninto the microscopic details that determine the dynamic behavior of the contact\nline, which is not possible with either continuum-scale simulations or\nexperiments. On the other hand, continuum-based models provide a link to the\nmacroscopic description of the system. In this Feature Article, we explore the\ncomplex range of physical factors, including the presence of surfactants, which\ngoverns the contact line motion through MD simulations. We also discuss links\nbetween continuum- and molecular-scale modeling and highlight the opportunities\nfor future developments in this area.",
        "positive": "Kinetic Analysis of Discrete Path Sampling Stationary Point Databases: Analysing stationary point databases to extract phenomenological rate\nconstants can become time-consuming for systems with large potential energy\nbarriers. In the present contribution we analyse several different approaches\nto this problem. First, we show how the original rate constant prescription\nwithin the discrete path sampling approach can be rewritten in terms of\ncommittor probabilities. Two alternative formulations are then derived in which\nthe steady-state assumption for intervening minima is removed, providing both a\nmore accurate kinetic analysis, and a measure of whether a two-state\ndescription is appropriate. The first approach involves running additional\nshort kinetic Monte Carlo (KMC) trajectories, which are used to calculate\nwaiting times. Here we introduce `leapfrog' moves to second-neighbour minima,\nwhich prevent the KMC trajectory oscillating between structures separated by\nlow barriers. In the second approach we successively remove minima from the\nintervening set, renormalising the branching probabilities and waiting times to\npreserve the mean first-passage times of interest. Regrouping the local minima\nappropriately is also shown to speed up the kinetic analysis dramatically at\nlow temperatures. Applications are described where rates are extracted for\ndatabases containing tens of thousands of stationary points, with effective\nbarriers that are several hundred times kT."
    },
    {
        "anchor": "Colloidal Dynamics on Disordered Substrates: Using Langevin simulations we examine driven colloids interacting with\nquenched disorder. For weak substrates the colloids form an ordered state and\ndepin elastically. For increasing substrate strength we find a sharp crossover\nto inhomogeneous depinning and a substantial increase in the depinning force,\nanalogous to the peak effect in superconductors. The velocity versus driving\nforce curve shows criticality at depinning, with a change in scaling exponent\noccuring at the order to disorder crossover. Upon application of a sudden pulse\nof driving force, pronounced transients appear in the disordered regime which\nare due to the formation of long-lived colloidal flow channels.",
        "positive": "Heterogeneous morphology and dynamics of polyelectrolyte brush\n  condensates in trivalent counterion solution: Recent experiments have shown that trivalent ion, spermidine$^{3+}$, can\nprovoke lateral microphase segregation in DNA brushes. Using molecular\nsimulations and simple theoretical arguments, we explore the effects of\ntrivalent counterions on polyelectrolyte brushes. At a proper range of grafting\ndensity, polymer size, and ion concentration, the brush polymers collapse\nheterogeneously into octopus-like surface micelles. Remarkably, the\nheterogeneity in brush morphology is maximized and the relaxation dynamics of\nchain and condensed ion are the slowest at the 1:3 stoichiometric concentration\nof trivalent ions to polyelectrolyte charge. A further increase of trivalent\nion concentration conducive to a charge inversion elicits modest reswelling and\nhomogenizes the morphology of brush condensate. Our study provides a new\ninsight into the origin of the diversity in DNA organization in cell nuclei as\nwell as the ion-dependent morphological variation in polyelectrolyte brush\nlayer of biological membranes."
    },
    {
        "anchor": "Viscous Decoupling Transitions for Individually Dragged Particles in\n  Systems with Quenched Disorder: We show that when an individual particle is dragged through an assembly of\nother particles in the presence of quenched disorder, a viscous decoupling\ntransition occurs between the dragged particle and the surrounding particles\nwhich is controlled by the quenched disorder. A counterintuitive consequence of\nthis transition is that the velocity of the dragged particle can be increased\nby increasing the strength or density of the quenched disorder. The decoupling\ntransition can also occur when the external drive on the dragged particle is\nincreased, and is observable as a clear signature in the velocity-force\nresponse.",
        "positive": "Direct measurements of the effects of salt and surfactant on interaction\n  forces between colloidal particles at water-oil interfaces: The forces between colloidal particles at a decane-water interface, in the\npresence of low concentrations of a monovalent salt (NaCl) and of the\nsurfactant sodium dodecylsulfate (SDS) in the aqueous subphase, have been\nstudied using laser tweezers. In the absence of electrolyte and surfactant,\nparticle interactions exhibit a long-range repulsion, yet the variation of the\ninteraction for different particle pairs is found to be considerable. Averaging\nover several particle pairs was hence found to be necessary to obtain reliable\nassessment of the effects of salt and surfactant. It has previously been\nsuggested that the repulsion is consistent with electrostatic interactions\nbetween a small number of dissociated charges in the oil phase, leading to a\ndecay with distance to the power -4 and an absence of any effect of electrolyte\nconcentration. However, the present work demonstrates that increasing the\nelectrolyte concentration does yield, on average, a reduction of the magnitude\nof the interaction force with electrolyte concentration. This implies that\ncharges on the water side also contribute significantly to the electrostatic\ninteractions. An increase in the concentration of SDS leads to a similar\ndecrease of the interaction force. Moreover the repulsion at fixed SDS\nconcentrations decreases over longer times. Finally, measurements of three-body\ninteractions provide insight into the anisotropic nature of the interactions.\nThe unique time-dependent and anisotropic interactions between particles at the\noil-water interface allow tailoring of the aggregation kinetics and structure\nof the suspension structure."
    },
    {
        "anchor": "Cooperative Lattice Dynamics and Anomalous Fluctuations of Microtubules: Microtubules have been in biophysical focus for several decades. Yet the\nconfusing and mutually contradicting results regarding their elasticity and\nfluctuations have shed some doubts on their present understanding. In this\npaper we expose the empirical evidence for the existence of discrete\nGDP-tubulin fluctuations between a curved and a straight configuration at room\ntemperature as well as for conformational tubulin cooperativity. Guided by a\nnumber of experimental findings, we build the case for a novel microtubule\nmodel, with the principal result that microtubules can spontaneously form\nmicron size cooperative helical states with unique elastic and dynamic\nfeatures. The polymorphic dynamics of the microtubule lattice resulting from\nthe tubulin bistability quantitatively explains several experimental puzzles\nincluding anomalous scaling of dynamic fluctuations of grafted microtubules,\ntheir apparent length-stiffness relation and their remarkably curved-helical\nappearance in general. We point out that tubulin dimers's multistability and\nits cooperative switching could participate in important cellular processes,\nand could in particular lead to efficient mechanochemical signalling along\nsingle microtubules.",
        "positive": "Very long-range attractive and repulsive forces in Model Colloidal\n  Dispersions: Experiments with polymer latex solutions show the coexistence of\norder-disorder structures of macroions. Because of the large macroions' sizes,\nthis order-disorder phase coexistence imply the existence of very long-range\nattractive and repulsive forces, which can not be explained in terms of\nconventional direct interaction potentials, which are short-range. Here we\napply an integral equations theory to a simple model for colloidal dispersions,\nat finite concentrations, calculate the particles distribution functions and\nthe involved effective forces. We find very long-range attractive and repulsive\nforces among the like-charged macroions. The distribution functions are in\nqualitative agreement with experimental results. The origin of these forces are\ndiscussed in terms of an energy-entropy balance."
    },
    {
        "anchor": "Universal amplitude in density-force relations for polymer chains in\n  confined geometries: Massive field theory approach: The universal density-force relation is analyzed and the correspondent\nuniversal amplitude ratio $B_{real}$ is obtained using the massive field theory\napproach in fixed space dimensions d=3 up to one-loop order. The layer monomer\ndensity profiles of ideal chains and real polymer chains with excluded volume\ninteraction in a good solvent between two parallel repulsive walls, one\nrepulsive and one inert wall are obtained. Besides, taking into account the\nDerjaguin approximation the layer monomer density profiles for dilute polymer\nsolution confined in semi-infinite space containing mesoscopic spherical\nparticle of big radius are calculated. The last mentioned situation is analyzed\nfor both cases when wall and particle are repulsive and for the mixed case of\nrepulsive wall and inert particle. The obtained results are in good agreement\nwith previous theoretical results and with the results of Monte Carlo\nsimulations.",
        "positive": "Elastohydrodynamic study of actin filaments using fluorescence\n  microscopy: We probed the bending of actin subject to external forcing and viscous drag.\nSingle actin filaments were moved perpendicular to their long axis in an\noscillatory way by means of an optically tweezed latex bead attached to one end\nof the filaments. Shapes of these polymers were observed by epifluorescence\nmicroscopy. They were found to be in agreement with predictions of semiflexible\npolymer theory and slender-body hydrodynamics. A persistence length of $7.4 \\pm\n0.2 \\mu$m could be extracted."
    },
    {
        "anchor": "Smectic and columnar ordering in length-polydisperse fluids of parallel\n  hard cylinders: We apply a recently proposed density functional for mixtures of parallel hard\ncylinders, based on Rosenfeld's fundamental measure theory, to study the effect\nof length-polydispersity on the relative stability between the smectic and\ncolumnar liquid crystal phases.To this purpose we derive from this functional\nan expression for the direct correlation function and use it to perform a\nbifurcation analysis. We compare the results with those obtained with a second\nand a third virial approximation of this function. All three approximations\nlead to the same conclusion: there is a terminal polydispersity beyond which\nthe smectic phase is less stable than the columnar phase. This result is in\nagreement with previous Monte Carlo simulations conducted on a freely rotating\nlength-polydisperse hard spherocylinder fluid, although the theories always\noverestimate the terminal polydispersity because the nematic-columnar phase\ntransition is first order and exhibits a wide coexistence gap. Both, the\nfundamental-measure functional and the third virial approximation, predict a\nmetastable nematic-nematic demixing. Conversely, according to second virial\napproximation this demixing might be stable at high values of the\npolydispersity, something that is observed neither in simulations nor in\nexperiments. The results of the fundamental-measure functional are\nquantitatively superior to those obtained from the other two approximations.\nThus this functional provides a promising route to map out the full phase\ndiagram of this system.",
        "positive": "Noise enhanced performance of ratchet cellular automata: We present the first experimental realization of a ratchet cellular automaton\n(RCA) which has been recently suggested as an alternative approach for\nperforming logical operations with interacting (quasi) particles. Our study was\nperformed with interacting colloidal particles which serve as a model system\nfor other dissipative systems i.e. magnetic vortices on a superconductor or\nions in dissipative optical arrays. We demonstrate that noise can enhance the\nefficiency of information transport in RCA and consequently enables their\noptimal operation at finite temperatures."
    },
    {
        "anchor": "Large magnetoresistance at room-temperature in small molecular weight\n  organic semiconductor sandwich devices: We present an extensive study of a large, room temperature negative\nmagnetoresistance (MR) effect in tris-(8-hydroxyquinoline) aluminum sandwich\ndevices in weak magnetic fields. The effect is similar to that previously\ndiscovered in polymer devices. We characterize this effect and discuss its\ndependence on field direction, voltage, temperature, film thickness, and\nelectrode materials. The MR effect reaches almost 10% at fields of\napproximately 10 mT at room temperature. The effect shows only a weak\ntemperature dependence and is independent of the sign and direction of the\nmagnetic field. Measuring the devices' current-voltage characteristics, we find\nthat the current depends on the voltage through a power-law. We find that the\nmagnetic field changes the prefactor of the power-law, whereas the exponent\nremains unaffected. We also studied the effect of the magnetic field on the\nelectroluminescence (MEL) of the devices and analyze the relationship between\nMR and MEL. We find that the largest part of MEL is simply a consequence of a\nchange in device current caused by the MR effect.",
        "positive": "Thermally activated breakdown in a simple polymer model: We consider the thermally activated fragmentation of a homopolymer chain. In\nour simple model the dynamics of the intact chain is a Rouse one until a bond\nbreaks and bond breakdown is considered as a first passage problem over a\nbarrier to an absorbing boundary. Using the framework of the Wilemski-Fixman\napproximation we calculate activation times of individual bonds for free and\ngrafted chains. We show that these times crucially depend on the length of the\nchain and the location of the bond yielding a minimum at the free chain ends.\nTheoretical findings are qualitatively confirmed by Brownian dynamics\nsimulations."
    },
    {
        "anchor": "Spontaneous chemical reactions between hydrogen and oxygen in\n  nanobubbles: Bulk nanobubbles (NBs) generated electrochemically by short voltage pulses of\nalternating polarity behave differently from those produced by regular methods.\nOnly bubbles smaller than $200\\;$nm are formed in the process and their\nconcentration is very high. Moreover, the bubbles containing both H2 and O2\ngases disappear quickly via the combustion reaction, although the reaction in\nsuch a small volume cannot happen according to the classical combustion theory.\nExperimental facts about these unusual NBs are reviewed and current\nunderstanding of the observed phenomena is provided. Visualisation methods of a\ncloud of NBs above the electrodes are briefly discussed. Experimental\nsignatures demonstrating the reaction between the gases in NBs are considered.\nA surface-assisted mechanism proposed for the combustion reactions in\nrestricted volumes with a high surface-to-volume ratio is discussed. It it\nexplained how the same mechanism may describe the audible explosion of\nmicrobubbles, that is observed in certain circumstances.",
        "positive": "Hydrolytic and lysozymic degradability of chitosan systems with\n  heparin-mimicking pendant groups: Chitosan (CT) is an antibacterial polysaccharide that has been investigated\nfor drug carriers, haemostats and wound dressings. For these applications,\ncustomised CT devices can often be obtained with specific experimental\nconditions, which can irreversibly alter native biopolymer properties and\nfunctions and lead to unreliable material behaviour. In order to investigate\nthe structure-function relationships in CT covalent networks, monosodium\n5-sulfoisophthalate (PhS) was selected as heparin-mimicking, growth\nfactor-binding crosslinking segment, whilst 1,4-phenylenediacetic acid (4Ph)\nand poly(ethylene glycol) bis(carboxymethyl) ether (PEG) were employed as\nsulfonic acid-free diacids of low and high crosslinker length respectively.\nHydrogels based on short crosslinkers (PhS and 4Ph) displayed increased\ncrosslink density, decreased swelling ratio as well as minimal hydrolytic and\nlysozymic degradation, whilst addition of lysozymes to PEG based networks\nresulted in 70 wt.-% mass loss. PhS-crosslinked CT hydrogels displayed the\nhighest loss (40 +/- 6 CFU%) of antibacterial activity upon incubation with\nPorphyromonas gingivalis, whilst respective extracts were tolerated by L929\nmouse fibroblasts."
    },
    {
        "anchor": "Heating leads to liquid-crystal and crystalline order in a\n  two-temperature active fluid of rods: We report phase separation and liquid-crystal ordering induced by scalar\nactivity in a system of Soft Repulsive Spherocylinders (SRS) of aspect ratio\n$L/D = 5 $. Activity was introduced by increasing the temperature of half of\nthe SRS (labeled \\textit{`hot'}) while maintaining the temperature of the other\nhalf constant at a lower value (labeled \\textit{`cold'}). The difference\nbetween the two temperatures scaled by the lower temperature provides a measure\nof the activity. Starting from different equilibrium initial phases, we find\nthat activity leads to segregation of the hot and cold particles. Activity also\ndrives the cold particles through a phase transition to a more ordered state\nand the hot particles to a state of less order compared to the initial\nequilibrium state. The cold components of a homogeneous isotropic (I) structure\nacquire nematic (N) and, at higher activity, crystalline (K) order. Similarly,\nthe cold zone of a nematic initial state undergoes smectic (Sm) and crystal\nordering above a critical value of activity while the hot component turns\nisotropic. We find that the hot particles occupy a larger volume and exert an\nextra kinetic pressure, confining, compressing and provoking an ordering\ntransition of the cold-particle domains.",
        "positive": "An FFT approach to the analysis of dynamic properties of gas/liquid\n  interfaces: The characterisation of the dynamic properties of viscoelastic monolayers of\nsurfactants at the gasliquid interface is very important in the analysis and\nprediction of foam stability. With most of the relevant dynamic processes being\nrapid (thermal fluctuation, film coalescence etc.) it is important to probe\ninterfacial dynamics at high deformation rates. Today, only few techniques\nallow this, one of them being the characterisation of the propagation of\nelectrocapillary waves on the liquid surface. Traditionally, this technique has\nbeen applied in a continuous mode (i.e. at constant frequency) in order to\nensure reliable accuracy. Here we explore the possibility to analyse the\npropagation of an excited pulse in order to access the interfacial properties\nin one single Fourier treatment over a wide range of frequencies. The main\nadvantage of this approach is that the measurement times and the required\nliquid volumes can be reduced significantly. This occurs at the cost of\nprecision in the measurement, due partly to the presence of a pronounced\nresonance of the liquid surface. The pulsed approach may therefore be used to\nprescan the surface response before a more in-depth scan at constant frequency;\nor to follow the changes of the interfacial properties during surfactant\nadsorption."
    },
    {
        "anchor": "Spontaneous Emulsification: Elucidation of the Local Processes: Micro and/or Nano sized emulsions are formed when an organic liquid gently\ncomes in contact with water in the presence of a surfactant, where no external\nagitation is required. Many years of research made it clear that the driving\nforce for spontaneous emulsification arises from the differences of the\nchemical potentials of various components in the organic and aqueous phases,\nwhich triggers diffusion coupled hydrodynamic fluctuation. While extraordinary\ntheoretical developments have taken place that attempted to describe these\nprocesses within the scopes of equilibrium and non-equilibrium thermodynamics,\nthe local processes underlying the spontaneous emulsification, however, still\nremain elusive. In this research, we investigate the local processes that\ninvolve the transfer of surfactant as well as water from one phase to another\n(i.e. water to oil), which results in the formation of water-in-oil emulsion in\nthe organic phase and, subsequently. Thes emulsions invert into oil-in-water\nemulsion, rather abruptly, as they cross the phase boundary. Studies based on\nUV spectroscopy and molecular dynamics indicate that these processes may\ninvolve explosive events and subsequent assembly of the fragments to other\norganized structures which are reminiscent of cusp catastrophe proposed earlier\nby Dickinson. These processes lead to either to a strong or a weak fluctuation\nof the component concentrations below the interface that also becomes evident\nin the fast (athermal) diffusion of the emulsion droplets from the interfacial\nregion farther into the bulk water. These events can be arrested suitably with\npolymeric additives.",
        "positive": "High intensity tapping regime in a frustrated lattice gas model of\n  granular compaction: In the frame of a well established lattice gas model for granular compaction,\nwe investigate the high intensity tapping regime where a pile expands\nsignificantly during external excitation. We find that this model shows the\nsame general trends as more sophisticated models based on molecular dynamic\ntype simulations. In particular, a minimum in packing fraction as a function of\ntapping strength is observed in the reversible branch of an annealed tapping\nprotocol."
    },
    {
        "anchor": "Designing Stress-Adaptive Dense Suspensions using Dynamic Covalent\n  Chemistry: The non-Newtonian behaviors of dense suspensions are central to their use in\ntechnological and industrial applications and arise from a network of\nparticle-particle contacts that dynamically adapts to imposed shear. Reported\nherein are studies aimed at explor-ing how dynamic covalent chemistry between\nparticles and the polymeric solvent can be used to tailor such stress-adaptive\ncontact networks leading to their unusual rheological behaviors. Specifically,\na room temperature dynamic thia-Michael bond is employed to rationally tune the\nequilibrium constant (Keq) of the polymeric solvent to the particle interface.\nIt is demonstrated that low Keq leads to shear thinning while high Keq produces\nantithixotropy, a rare phenomenon where the viscosity increases with shearing\ntime. It is proposed that an increase in Keq increases the polymer graft\ndensity at the particle surface and that antithixotropy primar-ily arises from\npartial debonding of the polymeric graft/solvent from the particle surface and\nthe formation of polymer bridges between particles. Thus, the implementation of\ndynamic covalent chemistry provides a new molecular handle with which to tailor\nthe macroscopic rheology of suspensions by introducing programable time\ndependence. These studies open the door to energy absorbing materials that not\nonly sense mechanical inputs and adjust their dissipation as a function of time\nor shear rate but can switch between these two modalities on demand.",
        "positive": "Simple generic picture of toughness in solid polymer blends: Toughness $\\mathcal{T}$ of a brittle polymeric solid can be enhanced by\nblending another compatible and ductile polymer. While this common wisdom is\ngenerally valid, a generic picture is lacking that connects the atomistic\ndetails to the macroscopic non-linear mechanics. Using all-atom and\ncomplementary generic simulations we show how a delicate balance between the\nside group contact density of the brittle polymers $\\rho_{\\rm c}$ and its\ndilution upon adding a second component controls $\\mathcal{T}$. A broad range\nof systems follows a universal trend in $\\mathcal{T}$ with ${\\rm d}\\rho_{\\rm\nc}/{\\rm d}\\varepsilon$, where $\\varepsilon$ is the tensile strain. The\nsimulation data is consistent with a simple model based on the parallel spring\nanalogy."
    },
    {
        "anchor": "Dynamical density functional theory for molecular and colloidal fluids:\n  a microscopic approach to fluid mechanics: In recent years, a number of dynamical density functional theories (DDFTs)\nhave been developed for describing the dynamics of the one-body density of both\ncolloidal and atomic fluids. In the colloidal case, the particles are assumed\nto have stochastic equations of motion and theories exist for both the case\nwhen the particle motion is over-damped and also in the regime where inertial\neffects are relevant. In this paper we extend the theory and explore the\nconnections between the microscopic DDFT and the equations of motion from\ncontinuum fluid mechanics. In particular, starting from the Kramers equation\nwhich governs the dynamics of the phase space probability distribution function\nfor the system, we show that one may obtain an approximate DDFT that is a\ngeneralisation of the Euler equation. This DDFT is capable of describing the\ndynamics of the fluid density profile down to the scale of the individual\nparticles. As with previous DDFTs, the dynamical equations require as input the\nHelmholtz free energy functional from equilibrium density functional theory\n(DFT). For an equilibrium system, the theory predicts the same fluid one-body\ndensity profile as one would obtain from DFT. Making further approximations, we\nshow that the theory may be used to obtain the mode coupling theory that is\nwidely used for describing the transition from a liquid to a glassy state.",
        "positive": "Motion of a sphere through an aging system: We have investigated the drag on a sphere falling through a clay suspension\nthat has a yield stress and exhibits rheological aging. The drag force\nincreases with both speed and the rest time between preparation of the system\nand the start of the experiment, but there exists a nonzero minimum speed below\nwhich steady motion is not possible. We find that only a very thin layer of\nmaterial around the sphere is fluidized when it moves, while the rest of\nsuspension is deformed elastically. This is in marked contrast to what is found\nfor yield-stress fluids that do not age."
    },
    {
        "anchor": "Breakdown of the Rosenfeld Excess Entropy Scaling Relations for the\n  Core-Softened Systems: Thermodynamic Path Dependence: We analyze the applicability of the Rosenfeld entropy scaling relations to\nthe systems with the core-softened potentials demonstrating the water-like\nanomalies. It is shown that the validity of the of Rosenfeld scaling relation\nfor the diffusion coefficient depends on the thermodynamic path which is used\nfor the calculations of the kinetic coefficients and the excess entropy. In\nparticular, it is valid along isochors, but it breaks down along isotherms.",
        "positive": "Shear induced phase separation of Wormlike micelles-nanoparticle system\n  : formation of a long-range ordered nanoparticle structure: Shearing of nanocomposites has shown to produce ordered nanostructures and\norientation in the polymeric matrix. Due to the importance of the formation of\nan ordered structure of nanoparticles in a polymeric matrix to device wearable,\nflexible and photonic materials, its useful to get an insight of the\nshear-induced ordering and other properties of the polymeric nanocomposites. In\nthis paper, we use a model Wormlike micellar matrix to study the arrangement\nand morphology of nanoparticles in the composite when the system is sheared\nusing a hybrid multiparticle dynamics and molecular dynamics simulation\ntechnique. We observe a shear-induced phase separation of nanoparticles as well\nas an increase in the long-range ordering of the nanostructures as a result of\nshear. We also show that in order to form a well-packed and highly ordered\nstructure, the nanoparticles with a smaller size should be preferred."
    },
    {
        "anchor": "Biomolecular Filters for Improved Separation of Output Signals in Enzyme\n  Logic Systems Applied to Biomedical Analysis: Biomolecular logic systems processing biochemical input signals and producing\n\"digital\" outputs in the form of YES/NO were developed for analysis of\nphysiological conditions characteristic of liver injury, soft tissue injury and\nabdominal trauma. Injury biomarkers were used as input signals for activating\nthe logic systems. Their normal physiological concentrations were defined as\nlogic-0 level, while their pathologically elevated concentrations were defined\nas logic-1 values. Since the input concentrations applied as logic 0 and 1\nvalues were not sufficiently different, the output signals being at low and\nhigh values (0, 1 outputs) were separated with a short gap making their\ndiscrimination difficult. Coupled enzymatic reactions functioning as a\nbiomolecular signal processing system with a built-in filter property were\ndeveloped. The filter process involves a partial back-conversion of the\noptical-output-signal-yielding product, but only at its low concentrations,\nthus allowing the proper discrimination between 0 and 1 output values.",
        "positive": "Comparing simulated specific heat of liquid polymers and oligomers to\n  experiments: The specific heat is a central property of condensed matter systems including\npolymers and oligomers in their condensed phases. Yet, predictions of this\nquantity from molecular simulations and successful comparisons to experimental\ndata are scarce if existing at all. One reason for this may be that the\ninternal energy and thus the specific heat cannot be coarse-grained so that\nthey defy their rigorous computation with united-atom models. Moreover, many\nmodes in a polymer barely contribute to the specific heat because of their\nquantum mechanical nature. Here, we demonstrate that an analysis of the\nmass-weighted velocity autocorrelation function allows specific heat\npredictions to be corrected for quantum effects so that agreement with\nexperimental data is on par with predictions of other routinely computed\nquantities. We outline how to construct corrections for both all-atom and\nunited-atom descriptions of chain molecules. Corrections computed for eleven\nhydrocarbon oligomers and commodity polymers deviate by less than\n$k_\\textrm{B}/10$ within a subset of nine molecules. Our results may benefit\nthe prediction of heat conductivity."
    },
    {
        "anchor": "Electro-osmosis on anisotropic super-hydrophobic surfaces: We give a general theoretical description of electro-osmotic flow at striped\nsuper-hydrophobic surfaces in a thin double layer limit, and derive a relation\nbetween the electro-osmotic mobility and hydrodynamic slip-length tensors. Our\nanalysis demonstrates that electro-osmotic flow shows a very rich behavior\ncontrolled by slip length and charge at the gas sectors. In case of uncharged\nliquid-gas interface, the flow is the same or inhibited relative to flow in\nhomogeneous channel with zero interfacial slip. By contrast, it can be\namplified by several orders of magnitude provided slip regions are uniformly\ncharged. When gas and solid regions are oppositely charged, we predict a flow\nreversal, which suggests a possibility of huge electro-osmotic slip even for\nelectro-neutral surfaces. On the basis of these observations we suggest\nstrategies for practical microfluidic mixing devices. These results provide a\nframework for the rational design of super-hydrophobic surfaces.",
        "positive": "Twist-bend nematic phase from Landau-de Gennes perspective: The understanding of self-organization in the twist-bend nematic\n$(N_\\text{TB})$ phase, identified in 2011 in liquid crystal dimers, is at the\nforefront of soft matter research worldwide. This new nematic phase develops\nstructural chirality in the isotropic $(I)$ and the uniaxial nematic\n$(N_\\text{U})$ phases, despite the fact that the molecules forming the\nstructure are chemically achiral. Molecular, shape-induced flexopolarization\nprovides a viable mechanism for a qualitative understanding of $N_\\text{TB}$\nand the related phase transitions. The key question that remains is whether\nwith this mechanism one can also explain quantitatively the presently existing\nexperimental data. To address this issue we propose a generalization of the\nmesoscopic Landau-de Gennes theory of nematics, where higher-order elastic\nterms of the alignment tensor are taken into account, in addition to the\nlowest-order flexopolarization coupling. The theory is not only capable of\nexplaining the appearance of $N_\\text{TB}$ but also stays in quantitative\nagreement with experimental data. In exemplary calculations, we take the data\nknown for CB7CB flexible dimer - the \"drosophila fly\" in the studies of\n$N_\\text{TB}$ [A. J\\'{a}kli et al., Rev. Mod. Phys. 90, 045004 (2018)] - and\nestimate the constitutive parameters of the model from temperature variation of\nthe nematic order parameter and the Frank elastic constants in the nematic\nphase. Then we seek for relative stability and properties of the isotropic,\nuniaxial nematic and twist-bend nematic phases. In particular, we evaluate\nvarious properties of $N_\\text{TB}$, like temperature variation of the\nstructure's wave vector, conical angle, flexopolarization, and remaining order\nparameters. We also look into the fine structure of $N_\\text{TB}$, like its\nbiaxiality - the property, which is difficult to access experimentally at the\nnanoscale."
    },
    {
        "anchor": "Elasticity Induced Force Reversal Between Active Spinning Particles in\n  Dense Passive Media: The self-organization of active particles is governed by their dynamic\neffective interactions. Such interactions are controlled by the medium in which\nsuch active agents reside. Here, we study the interactions between active\nagents in a dense non-active medium. Our system consists of actuated spinning\n(active) particles embedded in a dense monolayer of passive (non-active)\nparticles. We demonstrate that the presence of the passive monolayer alters\ndramatically the properties of the system and results in a reversal of the\nforces between active spinning particles from repulsive to attractive. The\norigin of such reversal is due to the coupling between the active stresses and\nelasticity of the system. This discovery provides a new mechanism for the\ninteraction between active agents in complex and structured media, opening up\nnew opportunities to tune the interaction range and directionality via the\nmechanical properties of the medium.",
        "positive": "Magnetic Nanoparticles in a Nematic Channel: A One-Dimensional Study: We study a ferromagnetic suspension or a suspension of magnetic nanoparticles\nin an anisotropic nematic medium, in three different one-dimensional\nvariational settings, ordered in terms of increasing complexity. The three\nmodels are featured by a nematic energy, a magnetic energy and a\nmagneto-nematic coupling energy and the experimentally observed patterns are\nmodelled as local or global energy minimizers. We numerically observe\npolydomains with distinct states of magnetization for weak to moderate\nmagneto-nematic coupling in our models. We demonstrate that these polydomains\nare stabilised by lowering the temperature (as in Mertelj et al., 2013) and\nthat the polydomain structures lose stability as the magneto-nematic coupling\nincreases. Some exact solutions for prototypical situations are also obtained."
    },
    {
        "anchor": "Rupture dynamics of flat colloidal films: Here, we report experimental results on the rupture of flat colloidal films\nover a large range of volume fractions, 0.00 $\\le \\phi\\le$ 0.47. The films are\nformed using a constant fluid volume, ruptured with a needle, and recorded\nusing a high-speed camera. We show that colloidal films rupture in a manner\nquantitatively similar to Newtonian fluids, even well into the shear thinning\nregime. These results are consistent with the well-known mechanism of the\nrupture of Newtonian films, where the rupture rim rolls outward collecting more\nfluid and thus film rupture is a shear-free process. However, in the case of\nspontaneous rupture under controlled humidity conditions, the same dense\ncolloidal films show exotic instabilities reminiscent of a wrinkling fabric on\nthe film surface. These instabilities were absent in manually ruptured films.\nWe hypothesize that these instabilities occur when the film thickness becomes\nthin enough to compete with the colloidal particle size, due to film drainage\nbefore spontaneous rupture. Thus, although non-Newtonian flow properties do not\ninfluence film rupture dynamics for thick enough films, the effect of\nmicrostructure has dramatic consequences in thinner films.",
        "positive": "Energetics of ion competition in the DEKA selectivity filter of neuronal\n  sodium channels: The energetics of ionic selectivity in the neuronal sodium channels is\nstudied. A simple model constructed for the selectivity filter of the channel\nis used. The selectivity filter of this channel type contains aspartate (D),\nglutamate (E), lysine (K), and alanine (A) residues (the DEKA locus). We use\nGrand Canonical Monte Carlo simulations to compute equilibrium binding\nselectivity in the selectivity filter and to obtain various terms of the excess\nchemical potential from a particle insertion procedure based on Widom's method.\nWe show that K$^{+}$ ions in competition with Na$^{+}$ are efficiently excluded\nfrom the selectivity filter due to entropic hard sphere exclusion. The\ndielectric constant of protein has no effect on this selectivity. Ca$^{2+}$\nions, on the other hand, are excluded from the filter due to a free energetic\npenalty which is enhanced by the low dielectric constant of protein."
    },
    {
        "anchor": "Active suspensions of bacteria and passive objects: a model for the near\n  field pair dynamics: Near field hydrodynamic interactions are essential to determine many\nimportant emergent behaviors observed in active suspensions, but have not been\nsuccessfully modeled so far. In this work we propose an effective model capable\nof efficiently capturing the essence of the near field hydrodynamic\ninteractions, validated numerically by a pedagogic model system consisting of\nan E. coli and a spherical tracer. The proposed model effectively captures all\nthe details of near field hydrodynamics through only a tensorial coefficient of\nresistance, which is fundamentally different from, and thus cannot be replaced\nby, an effective interaction of conservative nature. In a critical test case\nthat studies the scattering angle of the bacterium-tracer pair dynamics,\ncalculations based on the proposed model reveals a region in parameter space\nwhere the bacterium is trapped by the spherical tracer, a phenomenon that is\nregularly observed in experiments but cannot be explained by any existing\nmodel.",
        "positive": "Adsorption of highly charged Gaussian polyelectrolytes to oppositely\n  charged surfaces: In many biological processes highly charged biomolecules are adsorbed into\noppositely charged surfaces of macroions and membranes. They form strongly\ncorrelated structures close to the surface which can not be explained by the\nconventional Poisson-Boltzmann theory. Many of the flexible biomolecules can be\ndescribed by Gaussian polymers. In this work strong coupling theory is used to\nstudy the adsorption of highly charged Gaussian polyelectrolytes. Two cases of\nadsorptions are considered, when the Gaussian polyelectrolytes are confined a)\nby one charged wall, and b) between two charged walls. The effects of salt and\nthe geometry of the polymers on their adsorption- depletion transitions in the\nstrong coupling regime are discussed."
    },
    {
        "anchor": "Higher-order moment theories for dilute granular gases of smooth\n  hard-spheres: Grad's method of moments is employed to develop higher-order Grad's moment\nequations---up to first 26-moments---for granular gases within the framework of\nthe (inelastic) Boltzmann equation. The homogeneous cooling state of a freely\ncooling granular gas is investigated with the Grad's 26-moment equations in a\nsemi-linearized setting and it is shown that the granular temperature in the\nhomogeneous cooling state still decays according to Haff's law while the other\nhigher-order moments decay on a faster time scale. The constitutive relations\nfor stress and heat flux (the Navier--Stokes and Fourier relations) are\nobtained by performing a Chapman--Enskog-like expansion on the Grad's 26-moment\nequations and compared with those existing in the literature. The linear\nstability of the homogeneous cooling state is analyzed through the Grad's\n26-moment system and various sub-systems by decomposing them into longitudinal\nand transverse systems. It is found that one eigenmode in both longitudinal and\ntransverse systems in case of inelastic gases is unstable. By comparing the\neigenmodes from various theories, it is established that the 13-moment\neigenmode theory predicts that the unstable eigenmode remains unstable for all\nwavenumbers below a certain coefficient of restitution while any other\nhigher-order moment theory shows that this mode becomes stable above some\ncritical wavenumber for all values of coefficient of restitution. In\nparticular, the Grad's 26-moment theory leads to a smooth profile for the\ncritical wavenumber in contrast to the other considered theories. Furthermore,\nthe critical system size obtained through the Grad 26-moment and existing\ntheories are also in excellent agreement.",
        "positive": "Hydration of ions in two dimensional water: We present a 2D lattice model of water to study the effects of ion hydration\non the properties of water. We map the water molecules as lattice particles\nconsisting of a single Oxygen at the center of a site and two Hydrogen atoms on\neach side. The internal state of the system, such as the dipole moment at a\nsite, is defined with respect to the location of the Hydrogen atoms at the site\ndepending on their role in Hydrogen bonds (H-bonds) being a donor or an\nacceptor. We study the influence of the charge and the radius of the ion on the\ninsertion energy and on the H-bonds in the first and second hydration layers\naround the ion and in the bulk. In particular we analyze how the competing\ninteractions of the short-ranged H-bonds and the long-ranged electrostatics\ninfluence the hydration properties. The role of the ion both as a source of the\nelectrostatic interactions as well as a defect is also discussed. Our model\nalso shows the well known fact that the polarizability of the water molecules\ndestroys the hydrogen bond network and increases the dipole moment of the\nmolecules near the ion."
    },
    {
        "anchor": "The Shape of a M\u00f6bius Strip via Elastic Rod Theory Revisited: In 1993 Mahadevan and Keller used the Kirchhoff rod theory to predict the\nshape of a M\\\"obius band. Starting from the solution for a square cross-section\n(isotropic), they employ numerical continuation in the cross-sectional aspect\nratio in order to approach the solution for a thin strip. Certain smoothly\nvarying configurations are obtained. More recently in 2007, Starostin and van\nder Heijden pointed out that an actual M\\\"obius band \"localizes\" into a nearly\nflat triangular configuration as the ratio of the strip width to center-line\ncircumference is no longer small. Accordingly they return to the developable,\nthin-plate model of Sadowsky and Wunderlich, obtaining such localized shapes.\nIn this work we strike a middle ground between these two approaches. We employ\nthe standard two-director (special) Cosserat model, and we also use the\ncross-sectional aspect ratio as a numerical continuation parameter.\nNonetheless, we are able to capture both the smoothly varying shapes and the\nlocalized, nearly triangular configurations. Our point of departure is that we\ndo not always employ the strength-of-materials formula for the torsional\nstiffness - a standard feature of the Kirchhoff theory. Our key observation\ncomes from the usual Cosserat ansatz in light of developability, suggesting an\nincreasing torsional stiffness ratio (as well as one increasing bending\nstiffness ratio) as the thickness becomes small. We demonstrate that the\nclosed-loop configurations we obtain are stable with respect to small\nperturbations.",
        "positive": "Coordinated Beating of Algal Flagella is Mediated by Basal Coupling: Cilia and flagella often exhibit synchronized behavior; this includes phase\nlocking, as seen in {\\it Chlamydomonas}, and metachronal wave formation in the\nrespiratory cilia of higher organisms. Since the observations by Gray and\nRothschild of phase synchrony of nearby swimming spermatozoa, it has been a\nworking hypothesis that synchrony arises from hydrodynamic interactions between\nbeating filaments. Recent work on the dynamics of physically separated pairs of\nflagella isolated from the multicellular alga {\\it Volvox} has shown that\nhydrodynamic coupling alone is sufficient to produce synchrony. However, the\nsituation is more complex in unicellular organisms bearing few flagella. We\nshow that flagella of {\\it Chlamydomonas} mutants deficient in filamentary\nconnections between basal bodies display markedly different synchronization\nfrom the wild type. We perform micromanipulation on configurations of flagella\nand conclude that a mechanism, internal to the cell, must provide an additional\nflagellar coupling. In naturally occurring species with 4, 8, or even 16\nflagella, we find diverse symmetries of basal body positioning and of the\nflagellar apparatus that are coincident with specific gaits of flagellar\nactuation, suggesting that it is a competition between intracellular coupling\nand hydrodynamic interactions that ultimately determines the precise form of\nflagellar coordination in unicellular algae."
    },
    {
        "anchor": "Supercooled fluid-fluid phase transition in three dimensions from a\n  soft-core potential: To study the possibility of a fluid-fluid phase transition, we analyze a\nthree-dimensional soft-core isotropic potential for a one-component system. We\nutilize two independent numerical approaches, (i) integral equation in the\nhypernetted-chain approximation and (ii) molecular dynamics simulations, and\nfind for both approaches a fluid-fluid phase transition as well as the\nconventional gas-liquid critical point. We also study the possible existence of\na triple point in the supercooled fluid phase at which three phases---gas,\nhigh-density fluid, and low-density fluid---coexist.",
        "positive": "Computer Simulations of charged systems: In this brief contribution to the Proceedings of the NATO-ASI on\n``Electrostatic Effects in Soft Matter and Biophysics'', which took place in\nLes Houches from Oct. 1-13, 2000, we summarize in short aspects of the\nsimulations methods to study charged systems. After describing some basics of\nMonte Carlo and Molecular dynamics techniques, we describe a few methods to\ncompute long range interactions in periodic systems. After a brief detour to\nmean-field models, we describe our results obtained for flexible\npolyelectrolytes in good and bad solvents. We follow with a description of the\ninhomogeneity of the counterion distribution around finite chains, and continue\nthen with infinitely long, rodlike systems. The last part is devoted to the\nphenomenon of overcharging for colloidal particles and its explanation in terms\nof simple electrostatic arguments."
    },
    {
        "anchor": "When physics meets chemistry at dynamic glass transition: Can the laws of physics be unified. One of the most puzzling challenges is to\nreconcile physics and chemistry, where molecular physics meets condensed-matter\nphysics, resulting from the scaling effect and dynamic fluctuation of glassy\nmatter at the glass transition temperature. Pioneer of condensed-matter\nphysics, the Nobel Prize-winning physicist Philip Warren Anderson, wrote in\n1995: The deepest and most interesting unsolved problem in condensed-matter\nphysics is probably the theory of the nature of glassy state and the glass\ntransition. In 2005, the question of 'what is the nature of glassy state' was\nsuggested as one of the greatest scientific conundrums over the next\nquarter-century for Science's 125th anniversary. However, the nature of glassy\nstate and its connection to the glass transition have not been fully understood\nowing to the interdisciplinary complexity of physics and chemistry, where they\nare governed by the physical laws at condensed-matter and molecular scales,\nrespectively. Therefore, study on the glass transition becomes essential to\nexplore the working principles of scaling effect and dynamic fluctuation in\nglassy matter, as well as further reconcile the interdisciplinary complexity of\nphysics and chemistry.",
        "positive": "On the Formation of Equilibrium Gels via a Macroscopic Bond Limitation: Restricting the number of attractive physical \"bonds\" that can form between\nparticles in a fluid suppresses the usual demixing phase transition to very low\nparticle concentrations, allowing for the formation of open, percolated, and\nhomogeneous states, aptly called equilibrium or \"empty\" gels. Most\ndemonstrations of this concept have directly limited the microscopic particle\nvalence via anisotropic (patchy) attractions; however, an alternative\nmacroscopic valence limitation would be desirable for greater experimental\ntunability and responsiveness. One possibility, explored in this paper, is to\nemploy primary particles with attractions mediated via a secondary species of\nlinking particles. In such a system, the linker-to-primary particle ratio\nserves as a macroscopic control parameter for the average microscopic valence.\nWe show that the phase behavior of such a system predicted by Wertheim's first\norder perturbation theory is consistent with equilibrium gel formation: the\nprimary particle concentrations corresponding to the two-phase demixing\ntransition are significantly suppressed at both low and high linker-to-primary\nparticle ratios. Extensive molecular dynamics simulations validate these\ntheoretical predictions but also reveal the presence of loops of bonded\nparticles, which are neglected in the theory. Such loops cause densification\nand inhibit percolation, and hence the range of viable empty gel state\nconditions is somewhat reduced relative to the Wertheim theory predictions."
    },
    {
        "anchor": "Jamming and growth of dynamical heterogeneities versus depth for\n  granular heap flow: We report on grain dynamics versus depth for steady-state gravity-driven flow\nof grains along a heap formed between two parallel sidewalls. Near the surface\nthe flow is steady and fast, while far below there is no flow whatsoever;\ntherefore, a jamming transition occurs where depth is an effective control\nparameter for setting the distance from the transition. As seen previously, the\ntime-averaged velocity profile along the sidewall exhibits a nearly exponential\ndecay vs depth. Using speckle-visiblility spectroscopy (SVS), we find that\nvelocity fluctuations grow relative to the average on approach to jamming.\nIntroducing an image-based order parameter and the variance in its temporal\ndecay at a given depth, we also characterize the spatially heterogeneous nature\nof the dynamics and find that it increases on approach to jamming. In\nparticular, the important time and length scales for dynamical heterogeneities\nare found to grow almost exponentially as a function of depth. These dynamical\nchanges occur without noticeable change in structure, and are compared to\nbehavior found by experiment and simulation elsewhere in order to test the\nuniversality of the jamming concept. In particular we find that the size of the\nheterogeneities scales as the inertia number raised to the -1/3 power, in\nagreement with two recent simulations.",
        "positive": "Nematic-nematic demixing in polydisperse thermotropic liquid crystals: We consider the effects of polydispersity on isotropic-nematic phase\nequilibria in thermotropic liquid crystals, using a Maier-Saupe theory with\nfactorized interactions. A sufficient spread (approx. 50%) in the interaction\nstrengths of the particles leads to phase separation into two or more nematic\nphases, which can in addition coexist with an isotropic phase. The\nisotropic-nematic coexistence region widens dramatically as polydispersity is\nincreased, leading to re-entrant isotropic-nematic phase separation in some\nregions of the phase diagram. We show that similar phenomena will occur also\nfor non-factorized interactions as long as the interaction strength between any\ntwo particle species is lower than the mean of the intra-species interactions."
    },
    {
        "anchor": "Stratification, segregation and mixing of granular materials in quasi-2D\n  bounded heaps: Segregation and mixing of granular mixtures during heap formation have\nimportant consequences in industry and agriculture. This research investigates\nthree different final particle configurations of bi-disperse granular mixtures\n-- stratified, segregated and mixed -- during filling of quasi-two dimensional\nsilos. We consider a larger number and relatively wider range of control\nparameters than previous studies, including particle size ratio, flow rate,\nsystem size and heap rise velocity. The boundary between stratified and\nunstratified states is primarily controlled by the two-dimensional flow rate,\nwith the critical flow rate for the transition depending weakly on particle\nsize ratio and flowing layer length. In contrast, the transition from\nsegregated to mixed states is controlled by the rise velocity of the heap, a\ncontrol parameter not previously considered. The critical rise velocity for the\ntransition depends strongly on the particle size ratio.",
        "positive": "Wertheim perturbation theory: thermodynamics and structure of patchy\n  colloids: We critically discuss the application of the Wertheim's theory to classes of\ncomplex associating fluids that can be today engineered in the laboratory as\npatchy colloids and to the prediction of their peculiar gas-liquid phase\ndiagrams. Our systematic study, stemming from perturbative version of the\ntheory, allows us to show that, even at the simplest level of approximation for\nthe inter-cluster correlations, the theory is still able to provide a\nconsistent and stable picture of the behavior of interesting models of\nself-assembling colloidal suspension. We extend the analysis of a few cases of\npatchy systems recently introduced in the literature. In particular, we discuss\nfor the first time in detail the consistency of the structural description\nunderlying the perturbative approach and we are able to prove a consistency\nrelationship between the valence as obtained from thermodynamics and from the\nstructure for the one-site case. A simple analytical expression for the\nstructure factor is proposed."
    },
    {
        "anchor": "Manipulating the Glass Transition in Nanoscale: The intrinsic nature of glass states or glass transitions has been a mystery\nfor a long time. Recently, more and more studies tend to show that a glass\nlocates at a specific potential energy landscape (PEL). To explore how the\nflatness of the PEL related to glass transition, we develop a method to adjust\nthe PEL in a controllable manner. We demonstrate that a relatively flat PEL is\nnot only necessary but also sufficient for the formation of a nanoscale glass.\nWe show that: (1) as long as a nanocluster is located in a region of PEL with\nlocal minimum deep enough, it can undergo a first-order solid-liquid phase\ntransition; and (2) if a nanocluster is located in a relatively flat PEL, it\ncan undergo a glass transition. All these transitions are independent of its\nstructure symmetry, order or disorder. Our simulations also uncover the direct\ntransition from one potential energy minimum to another below the glass\ntransition temperature, which is the consequence of flat PELs.",
        "positive": "On the role of metastable intermediate states in the homogeneous\n  nucleation of solids from solution: The role of metastable liquid phases in vapor-crystal nucleation is studied\nusing Density Functional Theory(DFT). The model gives a semi-quantitatively\naccurate description of both the vapor-liquid-solid phase diagram for both\nsimple fluids (Lennard-Jones interactions) and of the\nlow-density/high-density/crystal phase diagram for model globular proteins (ten\nWolde-Frenkel interaction). The density profile is characterized by two local\norder parameters, the average density and the crystallinity. The bulk free\nenergy model is supplemented by squared-derivative terms in these order\nparameters to account for inhomogeneities thus producing a model similar in\nspirit to phase-field theory. It is shown that for both interaction models, the\nvapor-crystal part of the phase-diagram can be separated into regions for which\nmetastable liquid phases are more or less stable than the vapor, but always\nless stable than the solid. The former case allows for the possibility of\n\\emph{double nucleation} whereby liquid droplets nucleate from the vapor\nfollowed by a separate nucleation of the solid phase within the liquid\ndroplets. Whether or not this actually occurs depends on the relative free\nenergy barriers for vapor-solid and vapor-liquid nucleation and it is shown\nthat for simple fluids, double nucleation is indeed favored at sufficiently\nlarge supersaturation. Finally, by studying the minimum free energy path from\nthe vapor to the solid, the separate possibility of \\emph{transient\nnucleation}, where the vapor-solid transition involves a single nucleation\nevent but the sub-critical clusters tend to be liquid-like while small, is\nshown to also be possible when the metastable liquid exists, but the\nsupersaturation is too small for double nucleation."
    },
    {
        "anchor": "Monte Carlo Methods for Equilibrium and Nonequilibrium Problems in\n  Interfacial Electrochemistry: We present a tutorial discussion of Monte Carlo methods for equilibrium and\nnonequilibrium problems in interfacial electrochemistry. The discussion is\nillustrated with results from simulations of three specific systems: bromine\nadsorption on silver (100), underpotential deposition of copper on gold (111),\nand electrodeposition of urea on platinum (100).",
        "positive": "The critical pressure for microfiltration of oil-in-water emulsions\n  using slotted-pore membranes: The influence of geometrical parameters and fluid properties on the critical\npressure of permeation of an oil micro-droplet into a slotted pore is studied\nnumerically by solving the Navier-Stokes equations. We consider a long slotted\npore, which is partially blocked by the oil droplet but allows a finite\npermeate flux. An analytical estimate of the critical permeation pressure is\nobtained from a force balance model that involves the drag force from the flow\naround the droplet and surface tension forces as well as the pressure variation\ninside the pore. It was found that numerical results for the critical pressure\nas a function of the oil-to-water viscosity ratio, surface tension coefficient,\ncontact angle, and droplet radius agree well with theoretical predictions. Our\nresults show that the critical permeation pressure depends linearly on the\nsurface tension coefficient, while the critical pressure nearly saturates at\nsufficiently large values of the viscosity ratio or the droplet radius. These\nfindings are important for an optimal design and enhanced performance of\nmicrofiltration systems with slotted pores."
    },
    {
        "anchor": "Dynamical Scaling Exponents for Polymer Translocation through a Nanopore: We determine the scaling exponents of polymer translocation (PT) through a\nnanopore by extensive computer simulations of various microscopic models for\nchain lengths extending up to N=800 in some cases. We focus on the scaling of\nthe average PT time $\\tau \\sim N^{\\alpha}$ and the mean-square change of the PT\ncoordinate $<s^2(t)> \\sim t^\\beta$. We find $\\alpha=1+2\\nu$ and\n$\\beta=2/\\alpha$ for unbiased PT in 2D and 3D. The relation $\\alpha \\beta=2$\nholds for driven PT in 2D, with crossover from $\\alpha \\approx 2\\nu$ for short\nchains to $\\alpha \\approx 1+\\nu$ for long chains. This crossover is, however,\nabsent in 3D where $\\alpha = 1.42 \\pm 0.01$ and $\\alpha \\beta \\approx 2.2$ for\n$N \\approx 40-800$.",
        "positive": "A high pressure calorimetric experiment to validate the liquid-liquid\n  critical point hypothesis in water: An experimental proposal to test the existence of a liquid-liquid critical\npoint in water, based on high pressure calorimetric measurements, is presented\non this paper. Considering the existence of an intramolecular correlation in\nthe water molecule we show how the response of the specific heat at high\npressure is different depending on the existence, or not, of the second\ncritical point. If the liquid-liquid critical point hypothesis is true there\nmust be a maximum in the specific heat at some temperature $T>T_{H}$ for any\npressure $P>P_{c}$ (being $T_{H}$ the homogeneous nucleation temperature and\n$P_{c}$ the pressure of the second critical point). This maximum does not\nappear for the singularity free scenario."
    },
    {
        "anchor": "Charged Plate Beyond Mean-field: One-loop Corrections by Salt-density\n  Fluctuation: We present an exact field-theoretic formulation for a fluctuating, generally\nasymmetric, salt density in the presence of a charged plate. The non-linear\nPoisson-Boltzmann equation is obtained as the saddle-point of our field theory\naction. Focusing on the case of symmetric salt, we systematically compute\nfirst-order corrections arising from electrolytes fluctuation to the free\nenergy density, which can be explicitly obtained in closed form. We find that\nfor systems with low to moderate salt density, fluctuation corrections to the\nfree-energy depends sensitively on the salt concentration as well as their\ncharge valency. Further, we find that electrolyte fluctuation leads to a\nreduced electrostatic repulsion between two point-charges when they are close\nto the charged plate.",
        "positive": "Membrane simulation models from nm to $\u03bc$m scale: Recent developments in lipid membrane models for simulations are reviewed. To\nreduce computational costs, various coarse-grained molecular models have been\nproposed. Among them, implicit solvent (solvent-free) molecular models are\nrelatively more coarse-grained and efficient for simulating large bilayer\nmembranes. On a $\\mu$m scale, the molecular details are typically negligible\nand the membrane can be described as a continuous curved surface. The\ntheoretical models for fluid and elastic membranes with mesh or meshless\ndiscretizations are presented. As examples of applications, the dynamics of\nvesicles in flows, vesicle formation, and membrane fusion are presented."
    },
    {
        "anchor": "Short-time dynamics of monomers and dimers in quasi-two-dimensional\n  colloidal mixtures: We report on the short-time dynamics in colloidal mixtures made up of\nmonomers and dimers highly confined between two glass-plates. At low\nconcentrations, the experimental measurements of colloidal motion agree well\nwith the solution of the Navier-Stokes equation at low Reynolds numbers, which\ntakes into account the increase of the drag force on each particle due to\nwall-particle hydrodynamic forces. We find that the ratio of the short-time\ndiffusion coefficients of the monomer and that of the center of mass of the\ndimer remains independent of both the total packing fraction and the dimer\nmolar fraction up to concentrations near to the crystallization transition. The\nsame physical scenario is observed for the ratio between the parallel and\nperpendicular components of the short-time diffusion coefficients of the dimer.\nThis dynamical behavior is corroborated by means of Molecular Dynamics computer\nsimulations that explicitly include the particle-particle hydrodynamic forces\ninduced by the solvent. Thus, our results point out toward that the effects of\nthe particle-particle hydrodynamic interactions on the diffusion coefficients\nare identical and, thus, factorable in both species.",
        "positive": "Multi-Particle Collision Dynamics -- a Particle-Based Mesoscale\n  Simulation Approach to the Hydrodynamics of Complex Fluids: In this review, we describe and analyze a mesoscale simulation method for\nfluid flow, which was introduced by Malevanets and Kapral in 1999, and is now\ncalled multi-particle collision dynamics (MPC) or stochastic rotation dynamics\n(SRD). The method consists of alternating streaming and collision steps in an\nensemble of point particles. The multi-particle collisions are performed by\ngrouping particles in collision cells, and mass, momentum, and energy are\nlocally conserved. This simulation technique captures both full hydrodynamic\ninteractions and thermal fluctuations. The first part of the review begins with\na description of several widely used MPC algorithms and then discusses\nimportant features of the original SRD algorithm and frequently used\nvariations. Two complementary approaches for deriving the hydrodynamic\nequations and evaluating the transport coefficients are reviewed. It is then\nshown how MPC algorithms can be generalized to model non-ideal fluids, and\nbinary mixtures with a consolute point. The importance of angular-momentum\nconservation for systems like phase-separated liquids with different\nviscosities is discussed. The second part of the review describes a number of\nrecent applications of MPC algorithms to study colloid and polymer dynamics,\nthe behavior of vesicles and cells in hydrodynamic flows, and the dynamics of\nviscoelastic fluids."
    },
    {
        "anchor": "Free expansion of a Bose-Einstein condensate in a 1D optical lattice: We have experimentally investigated the free expansion of a Bose-Einstein\ncondensate in an array of two-dimensional traps created by a one-dimensional\noptical lattice. If the condensate held in a magnetic trap is loaded\nadiabatically into the lattice, the increase in chemical potential due to the\nadditional periodic potential is reflected in the expansion of the condensate\nafter switching off the magnetic trap. We have calculated the chemical\npotential from measurements of the transverse expansion of the condensate as a\nfunction of the lattice parameters.",
        "positive": "Direct observation of DNA dynamics in semi-dilute solutions in\n  extensional flow: The dynamic behavior of semi-dilute polymer solutions is governed by an\ninterplay between solvent quality, concentration, molecular weight, and flow\ntype. Semi-dilute solutions are characterized by large fluctuations in\nconcentration, wherein polymer coils interpenetrate but may not be\ntopologically entangled at equilibrium. In non-equilibrium flows, it is\ngenerally thought that polymer chains can self-entangle in semi-dilute\nsolutions, thereby leading to entanglements in solutions that are nominally\nunentangled at equilibrium. Despite recent progress, we still lack a complete\nmolecular-level understanding of these dynamics. In this work, we use single\nmolecule techniques to study the dynamics of semi-dilute solutions of DNA in\nplanar extensional flow, including polymer relaxation from high stretch,\ntransient stretching dynamics in step-strain experiments, and steady-state\nstretching in flow. Our results are consistent with a power-law scaling of the\nlongest polymer relaxation time in semi-dilute solutions, revealing an\neffective excluded volume exponent $\\nu$ = 0.56. We further studied the\nnon-equilibrium stretching dynamics in extensional flow, with results showing a\ndecrease in transient polymer stretch at moderate Weissenberg number and a\nmilder coil-to-stretch transition in semi-dilute solutions compared to dilute\nsolutions. Interestingly, a unique set of molecular conformations during the\ntransient stretching process for single polymers in semi-dilute solutions is\nobserved, which suggests transient stretching pathways for polymer chains in\nsemi-dilute solutions are qualitatively different than dilute solutions due to\nintermolecular interactions. Taken together, this work provides a molecular\nframework for understanding the non-equilibrium stretching dynamics of\nsemi-dilute solutions in strong flows."
    },
    {
        "anchor": "Effective interaction between a colloid and a soft interface near\n  criticality: Within mean-field theory we determine the universal scaling function for the\neffective force acting on a single colloid located near the interface between\ntwo coexisting liquid phases of a binary liquid mixture close to its critical\nconsolute point. This is the first study of critical Casimir forces emerging\nfrom the confinement of a fluctuating medium by at least one soft interface,\ninstead by rigid walls only as studied previously. For this specific system,\nour semi-analytical calculation illustrates that knowledge of the\ncolloid-induced, deformed shape of the interface allows one to accurately\ndescribe the effective interaction potential between the colloid and the\ninterface. Moreover, our analysis demonstrates that the critical Casimir force\ninvolving a deformable interface is accurately described by a universal scaling\nfunction, the shape of which differs from that one for rigid walls.",
        "positive": "Spontaneous knotting of a flexible fiber in chaotic flows: We consider the problem of an inextensible but flexible fiber advected by a\nsteady chaotic flow, and ask the simple question whether the fiber can\nspontaneously knot itself. Using a 1D Cosserat model, a simple local viscous\ndrag model and discrete contact forces, we explore the probability of finding\nknots at any given time when the fiber is interacting with the ABC class of\nflows. The bending rigidity is shown to have a marginal effect compared to that\nof increasing the fiber length. Complex knots are formed up to 11 crossings,\nbut some knots are more probable than others. The finite-time Lyapunov exponent\nof the flow is shown to have a positive effect on the knot probability.\nFinally, contact forces appear to be crucial since knotted configurations can\nremain stable for times much longer than the turnover time of the flow,\nsomething that is not observed when the fiber can freely cross itself."
    },
    {
        "anchor": "Thermodynamics of tubelike flexible polymers: In this work we present the general phase behavior of short tubelike flexible\npolymers. The geometric thickness constraint is implemented through the concept\nof the global radius of curvature. We use sophisticated Monte Carlo sampling\nmethods to simulate small bead-stick polymer models with Lennard-Jones\ninteraction among non-bonded monomers. We analyze energetic fluctuations and\nstructural quantities to classify conformational pseudophases. We find that the\ntube thickness influences the thermodynamic behavior of simple tubelike\npolymers significantly, i.e., for given temperature, the formation of secondary\nstructures strongly depends on the tube thickness.",
        "positive": "SAT-assembly: A new approach for designing self-assembling systems: We propose a general framework for solving inverse self-assembly problems,\ni.e. designing interactions between elementary units such that they assemble\nspontaneously into a predetermined structure. Our approach uses patchy\nparticles as building blocks, where the different units bind at specific\ninteraction sites (the patches), and we exploit the possibility of having\nmixtures with several components. The interaction rules between the patches is\ndetermined by transforming the combinatorial problem into a Boolean\nsatisfiability problem (SAT) which searches for solutions where all bonds are\nformed in the target structure. Additional conditions, such as the\nnon-satisfiability of competing structures (e.g. metastable states) can be\nimposed, allowing to effectively design the assembly path in order to avoid\nkinetic traps. We demonstrate this approach by designing and numerically\nsimulating a cubic diamond structure from four particle species that assembles\nwithout competition from other polymorphs, including the hexagonal structure."
    },
    {
        "anchor": "Beta-relaxation of non-polymeric liquids close to the glass transition: Dielectric beta-relaxation in a pyridine-toluene solution is studied close to\nthe glass transition. In the equilibrium liquid state the beta loss peak\nfrequency is not Arrhenius (as in the glass) but virtually\ntemperature-independent, while the maximum loss is strongly\ntemperature-dependent. Both loss peak frequency and maximum loss exhibit\nthermal hysteresis. A new annealing-state independent parameter involving loss\nand loss peak frequency is identified. This parameter has a simple Arrhenius\ntemperature-dependence and is unaffected by the glass transition.",
        "positive": "Aerial mucosalivary droplet dispersal distributions with implications\n  for disease mitigation: We investigate mucosalivary dispersal and deposition on horizontal surfaces\ncorresponding to human exhalations with physical experiments under still-air\nconditions. Synthetic fluorescence tagged sprays with size and speed\ndistributions comparable to human sneezes are observed with high-speed imaging.\nWe show that while some larger droplets follow parabolic trajectories, smaller\ndroplets stay aloft for several seconds and settle slowly with speeds\nconsistent with a buoyant cloud dynamics model. The net deposition distribution\nis observed to become correspondingly broader as the source height $H$ is\nincreased, ranging from sitting at a table to standing upright. We find that\nthe deposited mucosaliva decays exponentially in front of the source, after\npeaking at distance $x = 0.71$\\,m when $H = 0.5$\\,m, and $x = 0.56$\\,m when\n$H=1.5$\\,m, with standard deviations $\\approx 0.5$\\,m. Greater than 99\\% of the\nmucosaliva is deposited within $x = 2$\\,m, with faster landing times {\\em\nfurther} from the source. We then demonstrate that a standard nose and mouth\nmask reduces the mucosaliva dispersed by a factor of at least a hundred\ncompared to the peaks recorded when unmasked."
    },
    {
        "anchor": "Effects of colloid polydispersity on the phase behaviour of\n  colloid-polymer mixtures: We study theoretically the equilibrium phase behaviour of a mixture of\npolydisperse hard-sphere colloids and monodisperse polymers, modelled using the\nAsakura-Oosawa model within the free volume approximation of Lekkerkerker et\nal. We compute full phase diagrams in the plane of colloid and polymer volume\nfractions, using the moment free energy method. The intricate features of phase\nseparation in pure polydisperse colloids combine with the appearance of\npolymer-induced gas-liquid coexistence to give a rich variety of phase diagram\ntopologies as the polymer-colloid size ratio and the colloid polydispersity are\nvaried. Quantitatively, we find that polydispersity disfavours fluid-solid\nagainst gas-liquid separation, causing a substantial lowering of the threshold\nvalue above which stable two-phase gas-liquid coexistence appears. Phase splits\ninvolving two or more solids can occur already at low colloid concentration,\nwhere they may be kinetically accessible. We also analyse the strength of\ncolloidal size fractionation. When a solid phase separates from a fluid, its\npolydispersity is reduced most strongly if the phase separation takes place at\nlow colloid concentration and high polymer concentration, in agreement with\nexperimental observations. For fractionation in gas-liquid coexistence we\nlikewise find good agreement with experiment, as well as with perturbative\ntheories for near-monodisperse systems.",
        "positive": "Surface roughness induced stress concentration: When a body is exposed to external forces large local stresses may occur at\nthe surface because of surface roughness. Surface stress concentration is\nimportant for many applications and in particular for fatigue due to pulsating\nexternal forces. For randomly rough surfaces I calculate the probability\ndistribution of surface stress in response to a uniform external tensile stress\nwith the displacement vector field parallel to the rough surface. I present\nnumerical simulation results for the stress distribution $\\sigma (x,y)$ and\nshow that in a typical case, the maximum local tensile stress may be $\\sim 10$\ntimes bigger than the applied stress. I discuss the role of the stress\nconcentration on plastic deformation and surface crack generation and\npropagation."
    },
    {
        "anchor": "Studying polymer diffusiophoresis with Non-Equilibrium Molecular\n  Dynamics: We report a numerical study of the diffusiophoresis of short polymers using\nnon-equilibrium molecular dynamics simulations. More precisely, we consider\npolymer chains in a fluid containing a solute which has a concentration\ngradient, and examine the variation of the induced diffusiophoretic velocity of\nthe polymer chains as the interaction between the monomer and the solute is\nvaried. We find that there is a non-monotonic relation between the\ndiffusiophoretic mobility and the strength of the monomer-solute interaction.\nIn addition we find a weak dependence of the mobility on the length of the\npolymer chain, which shows clear difference from the diffusiophoresis of a\nsolid particle. Interestingly, the hydrodynamic flow through the polymer is\nmuch less screened than for pressure driven flows.",
        "positive": "Thermodynamic scaling of dynamics in polymer melts: Predictions from the\n  generalized entropy theory: Many glass-forming fluids exhibit a remarkable thermodynamic scaling in which\ndynamic properties, such as the viscosity, the relaxation time, and the\ndiffusion constant, can be described under different thermodynamic conditions\nin terms of a unique scaling function of the ratio rho^gamma/T, where rho is\nthe density, T is the temperature, and gamma is a material dependent constant.\nGiven the successes of the generalized entropy theory in elucidating the\ninfluence of molecular details on the universal properties of glass-forming\npolymers, this theory is extended here to investigate the thermodynamic scaling\nin polymer melts. The predictions of theory are in accord with the appearance\nof thermodynamic scaling for pressures not in excess of about 50 MPa. (The\nfailure at higher pressures arises due to inherent limitations of a lattice\nmodel.) In line with arguments relating the magnitude of gamma to the steepness\nof the repulsive part of the intermolecular potential, the abrupt, square-well\nnature of the lattice model interactions lead, as expected, to much larger\nvalues of the scaling exponent. Nevertheless, the theory is employed to study\nhow individual molecular parameters affect the scaling exponent in order to\nextract a molecular understanding of the information content contained in the\nexponent. The chain rigidity, cohesive energy, chain length, and the side group\nlength are all found to significantly affect the magnitude of the scaling\nexponent, and the computed trends agree well with available experiments. The\nvariations of gamma with these molecular parameters are explained by\nestablishing a correlation between the computed molecular dependence of the\nscaling exponent and the fragility. Thus, the efficiency of packing the\npolymers is established as the universal physical mechanism determining both\nthe fragility and the scaling exponent gamma."
    },
    {
        "anchor": "Magnetic Susceptibility Due to Disorder-Induced Neutral Solitons in\n  Interacting Polymer Chains: We study the magnetic response due to neutral solitons induced by disorder in\npolymer materials. We account for interchain interactions, which, if\nsufficiently strong, result in a bond-ordered phase, in which the neutral\nsolitons are bound into pairs. We analytically calculate the corresponding pair\nsize distribution. As the spins of the solitons have a distance dependent\nantiferromagnetic coupling, this allows us to calculate the magnetic\nsusceptibility in the ordered phase. At low temperatures, the result deviates\nfrom the usual Curie behavior in a way that depends on the relative strength of\nthe disorder and the interchain interactions. We compare our results to the\nobserved magnetic susceptibility of trans-polyacetylene and we suggest new\nexperiments extending towards lower temperatures.",
        "positive": "Depth-dependent hysteresis in adhesive elastic contacts at large surface\n  roughness: Contact force--indentation depth measurements in contact experiments\ninvolving compliant materials, such as polymers and gels, show a hysteresis\nloop whose size depends on the maximum indentation depth. This depth-dependent\nhysteresis (DDH) is not explained by classical contact mechanics theories and\nwas believed to be due to effects such as material viscoelasticity, plasticity,\nsurface polymer interdigitation, and moisture, etc. It has been observed that\nthe DDH energy loss initially increases and then decreases with roughness. A\nmechanics model based on the occurrence of adhesion and roughness related\nsmall-scale instabilities was presented by one of the authors for explaining\nDDH. However, that model only applies in the regime of infinitesimally small\nsurface roughness, and consequently it does not capture the decrease in energy\nloss with surface roughness at the large roughness regime. We present a new\nmechanics model that applies in the regime of large surface roughness based on\nthe Maugis--Dugdale theory of adhesive elastic contacts and Nayak's theory of\nrough surfaces. The model captures the trend of decreasing energy loss with\nincreasing roughness. It also captures the experimentally observed dependencies\nof energy loss on the maximum indentation depth, and material and surface\nproperties."
    },
    {
        "anchor": "The isotropic-cholesteric phase transition of filamentous virus\n  suspensions as a function of rod length and charge: The viruses studied are genetically engineered, charged, semiflexible\nfilamentous bacteriophages that are structurally identical to M13 virus, but\ndiffer either in contour length or surface charge. While varying contour length\n(L) we assume the persistence length (P) remains constant, and thus we alter\nthe rod flexibility (L/P). Surface charge is altered both by changing solution\npH and by comparing two viruses, fd and M13, which differ only by the\nsubstitution of one charged for one neutral amino acid per virus coat protein.\nWe measure both the isotropic and cholesteric coexistence concentrations as\nwell as the nematic order parameter after unwinding the cholesteric phase in a\nmagnetic field. The isotropic-cholesteric transition experimental results agree\nsemi-quantitatively with theoretical predictions for semiflexible, charged\nrods.",
        "positive": "Molecular motors govern liquid-like ordering and fusion dynamics of\n  bacterial colonies: Bacteria can adjust the structure of colonies and biofilms to enhance their\nsurvival rate under external stress. Here, we explore the link between\nbacterial interaction forces and colony structure. We show that the activity of\nextracellular pilus motors enhances local ordering and accelerates fusion\ndynamics of bacterial colonies. The radial distribution function of mature\ncolonies shows local fluid-like order. The degree and dynamics of ordering are\ndependent on motor activity. At a larger scale, the fusion dynamics of two\ncolonies shows liquid-like behavior whereby motor activity strongly affects\ntension and viscosity."
    },
    {
        "anchor": "Incompressibility of polydisperse random close packed colloidal\n  particles: We use confocal microscopy to study a random close packed sample of colloidal\nparticles. We introduce an algorithm to estimate the size of each particle.\nTaking into account their sizes, we compute the compressibility of the sample\nas a function of wave vector $q$, and find that this compressibility vanishes\nlinearly as $q \\rightarrow 0$. The particle sizes must be considered to\ncalculate the compressibility properly. These results also suggest that the\nexperimental packing is hyperuniform.",
        "positive": "Surprising mappings of 2D polar active fluids to 2D soap and 1D\n  sandblasting: Active fluids and growing interfaces are two well-studied but very different\nnon-equilibrium systems. Each exhibits non-equilibrium behavior quite different\nfrom that of their equilibrium counterparts. Here we demonstrate a surprising\nconnection between these two: the ordered phase of incompressible polar active\nfluids in two spatial dimensions without momentum conservation, and growing\none-dimensional interfaces (that is, the 1+1-dimensional Kardar-Parisi-Zhang\nequation), in fact belong to the same universality class. This universality\nclass also includes two equilibrium systems : two-dimensional smectic liquid\ncrystals, and a peculiar kind of constrained two-dimensional ferromagnet. We\nuse these connections to show that two-dimensional incompressible flocks are\nrobust against fluctuations, and exhibit universal long-ranged, anisotropic\nspatio-temporal correlations of those fluctuations. We also thereby determine\nthe exact values of the anisotropy exponent $\\zeta$ and the roughness exponents\n$\\chi_{_{x,y}}$ that characterize these correlations."
    },
    {
        "anchor": "Dense Random Packing of Disks With a Power-Law Size Distribution in\n  Thermodynamic Limit: Fractal-like Properties: The correlation properties of a dense random system of disks with a power-law\nsize distribution are analyzed in momentum space in the thermodynamic limit.\nThe limit assumes that the total number the disks increases infinitely, while\nthe mean density of the disk centers and the range of the size distribution are\nkept constant. The structure factor dependence on momentum transfer is\ninvestigated for various numbers of disks and extrapolated to the thermodynamic\nlimit. The fractal power-law decay of the structure factor is recovered in\nmomentum space within the fractal range, which corresponds to the range of the\nsize distribution in real space. The fractal exponent coincides with the\nexponent of the power-law size distribution as was shown previously by the\nauthors [Cherny, Anitas, Osipov, J. Chem. Phys. 158 (4), 044114 (2023)]. The\nfinite-size effects are also studied at very small momentum of order of the\ninverse system size. We show that the structure factor is parabolic in this\nregion and calculate the prefactor analytically. The obtained results reveal\nfractal-like properties of the packing. Our findings can be used to analyze\nsmall-angle scattering from such systems.",
        "positive": "Inertial Effects on Kinetics of Motility-Induced Phase Separation: Motility-induced phase separation (MIPS) is of great importance and has been\nextensively researched in overdamped systems, nevertheless, what impacts\ninertia will bring on kinetics of MIPS is lack of investigation. Here, we find\nthat, not only the phase transition changes from continuous to discontinuous,\nbut also the formation of clusters exhibits a nucleation-like process without\nany coarsening regime, different from spinodal decomposition in the overdamped\ncase. This remarkable kinetics stems from a competition between\nactivity-induced accumulation of particles and inertia-induced suppression of\nclustering process. More interestingly, the discontinuity of MIPS still exists\neven when the ratio of particle mass to the friction coefficient reduces to be\nvery small such as 0.0001. Our findings emphasize the importance of inertia in\nkinetics of MIPS, and may open a new perspective on understanding the nature of\nMIPS in active systems."
    },
    {
        "anchor": "Equilibrium state of a cylindrical particle with flat ends in nematic\n  liquid crystals: A continuum theory is employed to numerically study the equilibrium\norientation and defect structures of a circular cylindrical particle with flat\nends under a homeotropic anchoring condition in a uniform nematic medium.\nDifferent aspect ratios of this colloidal geometry from thin discotic to long\nrod-like shapes and several colloidal length scales ranging from mesoscale to\nnanoscale are investigated. We show that the equilibrium state of this\ncolloidal geometry is sensitive to the two geometrical parameters: aspect ratio\nand length scale of the particle. For a large enough mesoscopic particle, there\nis a specific asymptotic equilibrium angle associated to each aspect ratio.\nUpon reducing the particle size to nanoscale, the equilibrium angle follows a\ndescending or ascending trend in such a way that the equilibrium angle of a\nparticle with the aspect ratio bigger than 1:1 (a discotic particle) goes to a\nparallel alignment with respect to the far field nematic, whereas the\nequilibrium angle for a particle with the aspect ratio 1:1 and smaller (a\nrod-like particle) tends toward a perpendicular alignment to the uniform\nnematic direction. The discrepancy between the equilibrium angles of the\nmesoscopic and nanoscopic particles originates from the significant differences\nbetween their defect structures. The possible defect structures related to\nmesoscopic and nanoscopic colloidal particles of this geometry are also\nintroduced.",
        "positive": "Resonance in Bose-Einstein condensate oscillation from a periodic\n  variation in scattering length: Using the explicit numerical solution of the axially-symmetric\nGross-Pitaevskii equation we study the oscillation of the Bose-Einstein\ncondensate induced by a periodic variation in the atomic scattering length $a$.\nWhen the frequency of oscillation of $a$ is an even multiple of the radial or\naxial trap frequency, respectively, the radial or axial oscillation of the\ncondensate exhibits resonance with novel feature. In this nonlinear problem\nwithout damping, at resonance in the steady state the amplitude of oscillation\npasses through maximum and minimum. Such growth and decay cycle of the\namplitude may keep on repeating. Similar behavior is also observed in a\nrotating Bose-Einstein condensate."
    },
    {
        "anchor": "Simulation Study of Internal and Surface waves of Vertically Vibrated\n  Granular Materials: Molecular dynamical (MD) simulations are performed to simulate two\ndimensional vibrofluidized granular materials in this work. Statistics on\nsimulation results indicate that there exist shocks propagating upward in each\nvibrating cycle. Under certain driving parameters surface waves similar to\nFaraday instability in normal fluid coexist with internal waves. Relationship\nbetween the two kinds of waves is explored. Moreover simulation results\nindicate that periodically structured bottom can change the dispersion\nrelationship and amplitude of surface waves.",
        "positive": "Micelle Formation and the Hydrophobic Effect: The tendency of amphiphilic molecules to form micelles in aqueous solution is\na consequence of the hydrophobic effect. The fundamental difference between\nmicelle assembly and macroscopic phase separation is the stoichiometric\nconstraint that frustrates the demixing of polar and hydrophobic groups. We\npresent a theory for micelle assembly that combines the account of this\nconstraint with a description of the hydrophobic driving force. The latter\narises from the length scale dependence of aqueous solvation. The theoretical\npredictions for temperature dependence and surfactant chain length dependence\nof critical micelle concentrations for nonionic surfactants agree favorably\nwith experiment."
    },
    {
        "anchor": "Modelling Polymer Compression in Flow: Semi-dilute Solution Behaviour: Rheo-optical measurements on Polyemethyl methacrylate (PMMA) and\n4-Butoxycarbonylmethylurethane (4-BCMU) show that these synthetic random coil\npolymer chains compress in Couette flow at semi-dilute concentrations. All\nprevious models of polymer flow behaviour have assumed that the chains extend.\nA new model of polymers in flow in semi-dilute solution is presented where the\nchains compress in accord with the experimental findings. The chains are\nmodeled as simple blobs exposed to a linear shear gradient which results in a\ncompressive hydrodynamic force on the chain. Equating the hydrodynamic and\nelastic forces predicts chain compression with shear rate. The model also\npredicts a power law behaviour for polymer shear thinning of -2/3. The\npredicted power law for the decrease in radius with shear rate is -1/9 in close\nagreement with the measured value of -0.09+/-0.02 for both polymer systems.",
        "positive": "Computing 3D chromatin configurations from contact probability maps by\n  Inverse Brownian Dynamics: The three-dimensional organization of chromatin, on the length scale of a few\ngenes, is crucial in determining the functional state - accessibility and the\namount of gene expression - of the chromatin. Recent advances in chromosome\nconformation capture experiments provide partial information on the chromatin\norganization in a cell population, namely the contact count between any segment\npairs, but not on the interaction strength that leads to these contact counts.\nHowever, given the contact matrix, determining the complete 3D organization of\nthe whole chromatin polymer is an inverse problem. In the present work, a novel\nInverse Brownian Dynamics (IBD) method based on a coarse grained bead-spring\nchain model has been proposed to compute the optimal interaction strengths\nbetween different segments of chromatin such that the experimentally measured\ncontact count probability constraints are satisfied. Applying this method to\nthe {\\alpha}-globin gene locus in two different cell types, we predict the 3D\norganizations corresponding to active and repressed states of chromatin at the\nlocus. We show that the average distance between any two segments of the region\nhas a broad distribution and cannot be computed as a simple inverse relation\nbased on the contact probability alone. The results presented for multiple\nnormalization methods suggest that all measurable quantities may crucially\ndepend on the nature of normalization. We argue that by experimentally\nmeasuring predicted quantities, one may infer the appropriate form of\nnormalization."
    },
    {
        "anchor": "Creep failure of amorphous solids under tensile stress: Applying constant tensile stress to a piece of amorphous solid results in a\nslow extension, followed by an eventual rapid mechanical collapse. This \"creep\"\nprocess is of paramount engineering concern, and as such was the subject of\nstudy in a variety of materials, for more than a century. Predictive theories\nfor $\\tau_w$, the expected time of collapse, are lacking, mainly due to its\ndependence on a bewildering variety of parameters, including temperature,\nsystem size, tensile force, but also the detailed microscopic interactions\nbetween constituents. The complex dependence of the collapse time on all the\nparameters is discussed below, using simulations of strip of amorphous\nmaterial. Different scenarios are observed for ductile and brittle materials,\nresulting in serious difficulties in creating an all-encompassing theory that\ncould offer safety measures for given conditions. A central aim of this paper\nis to employ scaling concepts, to achieve data collapse for the probability\ndistribution function (pdf) of $\\ln{\\tau_w}$. The scaling ideas result in a\nuniversal function which provides a prediction of the pdf of $\\ln{\\tau_w}$ for\nout-of-sample systems, from measurements at other values of these parameters.\nThe predictive power of the scaling theory is demonstrated for both ductile and\nbrittle systems. Finally, we present a derivation of universal scaling function\nfor brittle materials. The ductile case appears to be due to a plastic necking\ninstability and is left for future research.",
        "positive": "Shear Thickening of Dense Suspensions: The Role of Friction: Shear thickening of particle suspensions is characterized by a transition\nbetween lubricated and frictional contacts between the particles. Using 3D\nnumerical simulations, we study how the inter-particle friction coefficient\ninfluences the effective macroscopic friction coefficient and hence the\nmicrostructure and rheology of dense shear thickening suspensions. We propose\nexpressions for effective friction coefficient in terms of distance to jamming\nfor varying shear stresses and particle friction coefficient values. We find\neffective friction coefficient to be rather insensitive to interparticle\nfriction, which is perhaps surprising but agrees with recent theory and\nexperiments."
    },
    {
        "anchor": "Electrical properties of polyetherimide thin films: Nonparametric\n  dielectric reponse analysis with distribution of relaxation times: High temperature polymeric materials for electrical insulation and energy\nstorage are needed for transformational power applications such as pulsed-power\nand hyrid electrical vehicles. One of the candidate materials has been\npolyetherimide, an amourphous thermoplastic with a glass transition over 200C.\nHere dielectric studies on the material are reported by taking into account the\npolarization and conduction processes in the polyetherimide.",
        "positive": "Interactions of vortices with rarefaction solitary waves in a\n  Bose-Einstein condensate and their role in the decay of superfluid turbulence: There are several ways to create the vorticity-free solitary waves --\nrarefaction pulses -- in condensates: by the process of strongly nonequilibrium\ncondensate formation in a weakly interacting Bose gas, by creating local\ndepletion of the condensate density by a laser beam, and by moving a small\nobject with supercritical velocities. Perturbations created by such waves\ncolliding with vortices are studied in the context of the Gross-Pitaevskii\nmodel. We find that the effect of the interactions consists of two competing\nmechanisms: the creation of vortex line as rarefaction waves acquire\ncirculation in a vicinity of a vortex core and the loss of the vortex line to\nsound due to Kelvin waves that are generated on vortex lines by rarefaction\npulses. When a vortex ring collides with a rarefaction wave, the ring either\nstabilises to a smaller ring after emitting sound through Kelvin wave radiation\nor the entire energy of the vortex ring is lost to sound if the radius of the\nring is of the order of the healing length. We show that during the time\nevolution of a tangle of vortices, the interactions with rarefaction pulses\nprovide an important dissipation mechanism enhancing the decay of superfluid\nturbulence."
    },
    {
        "anchor": "Quasi-static deformation of yield stress materials: homogeneous or\n  localized?: We analyze a mesoscopic model of a shear stress material with a three\ndimensional slab geometry, under an external quasistatic deformation of a\nsimple shear type. Relaxation is introduced in the model as a mechanism by\nwhich an unperturbed system achieves progressively mechanically more stable\nconfigurations. Although in all cases deformation occurs via localized plastic\nevents (avalanches) we find qualitatively different behavior depending on the\ndegree of relaxation in the model. For no or low relaxation yielding is\nhomogeneous in the sample, and even the largest avalanches become negligible in\nsize compared with the system size (measured as the thickness of the slab\n$L_z$) when this is increased. On the contrary, for high relaxation the\ndeformation localizes in an almost two dimensional region where all avalanches\noccur. Scaling analysis of the numerical results indicates that in this case\nthe linear size of the largest avalanches is comparable with $L_z$ even when\nthis becomes very large. We correlate the two scenarios with a qualitative\ndifference in the flow curve of the system in the two cases, which is\nmonotonous in the first case, or of the velocity weakening type in the second\ncase.",
        "positive": "Characteristic spatial scale of vesicle pair interactions in a plane\n  linear flow: We report the experimental studies on interaction of two vesicles trapped in\na microfluidic analog of four-roll mill, where a plane linear flow is realized.\nWe found that the dynamics of a single vesicle is significantly altered by the\npresence of another vesicle at separation distances up to about 3.2 \\div 3.7\ntimes of effective radius of the vesicles. This is supported by direct\nmeasurements of a single vesicle back-reaction on the velocity field. Thus, the\nexperiment provides the lower bound for the interaction scale of vesicles and\nso the corresponding upper bound for the volume fraction \\phi=0.08 \\div 0.13 of\nnon-interacting vesicle suspensions."
    },
    {
        "anchor": "Intruder Dynamics in a Frictional Granular Fluid: A Molecular Dynamics\n  Study: We study the dynamics of an intruder moving through a fluidized granular\nmedium in three dimensions ($d=3$). The intruder and grains have both\ntranslational and rotational degrees of freedom. The energy-dissipation\nmechanism is solid friction between all pairs of particles. We keep the\ngranular system fluidized even at rather high densities by randomly perturbing\nthe linear and angular velocities of the grains. We apply a constant external\nforce of magnitude $F$ to the intruder, and obtain its steady state velocity\n$V_s$ in the center-of-mass frame of the grains. The $F$-$V_s$ relation is of\ngreat interest in the industrial processing of granular matter, and has been\nthe subject of most experiments on this problem. We also obtain the mobility,\nwhich is proportional to the inverse viscosity, as a function of the volume\nfraction $\\phi$. This is shown to diverge at the jamming volume fraction. For\n$\\phi$ below the jamming fraction, we find that $V_s \\sim F$ for small $F$ and\n$V_s \\sim F^{1/2}$ for large $F$. The intruder shows diffusive motion in the\nplane perpendicular to the direction of the external force.",
        "positive": "Contact mechanics of adhesive beams. Part II: Low to high indentation: In this article, we extended our approach, that is mentioned in part 1, to\nmodel the indentation of an adhesive beam by a rigid cylindrical punch. We\nconsidered clamped and simply supported beams for this study. We first modeled\nthese beams as infinite length elastic layers which obey the kinetic and\nkinematic constraints imposed by the end supports. The adhesion effects are\nconsidered via the Dugdale-Barenblatt model based adhesive zone model. Solving\nthe governing equations of this infinite layer along with its boundary\nconditions, we obtain a set of coupled Fredholm integral equations of first\nkind. These integral equations are then solved employing the collocation\ntechnique. The results obtained are then compared with finite element (FE)\nsimulations and the previously published results for the non-adhesive case. We\nalso obtained the results for the well-known Johnson-Kendall-Roberts (JKR)\napproximation of the contact. Finally we investigated the effect of various\nadhesive strengths on the contact parameters and showed the transition of the\nresults from 'Hertzian' to 'JKR' approximation."
    },
    {
        "anchor": "Light-harvesting in bacteria exploits a critical interplay between\n  transport and trapping dynamics: Light-harvesting bacteria Rhodospirillum Photometricum were recently found to\nadopt strikingly different architectures depending on illumination conditions.\nWe present analytic and numerical calculations which explain this observation\nby quantifying a dynamical interplay between excitation transfer kinetics and\nreaction center cycling. High light-intensity membranes (HLIM) exploit\ndissipation as a photo-protective mechanism, thereby safeguarding a steady\nsupply of chemical energy, while low light-intensity membranes (LLIM)\nefficiently process unused illumination intensity by channelling it to open\nreaction centers. More generally, our analysis elucidates and quantifies the\ntrade-offs in natural network design for solar energy conversion.",
        "positive": "Visualization of membrane loss during the shrinkage of giant vesicles\n  under electropulsation: We study the effect of permeabilizing electric fields applied to two\ndifferent types of giant unilamellar vesicles, the first formed from EggPC\nlipids and the second formed from DOPC lipids. Experiments on vesicles of both\nlipid types show a decrease in vesicle radius which is interpreted as being due\nto lipid loss during the permeabilization process. We show that the decrease in\nsize can be qualitatively explained as a loss of lipid area which is\nproportional to the area of the vesicle which is permeabilized. Three possible\nmechanisms responsible for lipid loss were directly observed: pore formation,\nvesicle formation and tubule formation."
    },
    {
        "anchor": "Growing structure based on viscous actuation of constrained multistable\n  elements: Growing soft materials which follow a 3D path in space are critical to\napplications such as search and rescue and minimally invasive surgery. Here, we\npresent a concept for a single-input growing multi-stable soft material, based\non a constrained straw-like structure. This class of materials are capable of\nmaneuvering and transforming their configuration by elongation while executing\nmultiple turns. This is achieved by sequenced actuation of bi-stable frusta\nwith predefined constraints. Internal viscous flow and variations in the\nstability threshold of the individual cells enable sequencing and control of\nthe robot's movement so as to follow a desired 3D path as the structure grows.\nWe derive a theoretical description of the shape and dynamics resulting from a\nparticular set of constraints. To validate the model and demonstrate the\nsuggested concept, we present experiments of maneuvering in models of\nresidential and biological environments. In addition to performing complex 3D\nmaneuvers, the tubular structure of these robots may also be used as a conduit\nto reach inaccessible regions, which is demonstrated experimentally.",
        "positive": "Collective motion of Active Brownian Particles with polar alignment: We present a comprehensive computational study of the collective behavior\nemerging from the competition between self-propulsion, excluded volume\ninteractions and velocity-alignment in a two-dimensionnal model of active\nparticles. We consider an extension of the Active Brownian Particles model\nwhere the self-propulsion direction of the particles aligns with the one of\ntheir neighbors. We analyze the onset of collective motion (flocking) in a\nlow-density regime (10% surface area) and show that it is mainly controlled by\nthe strength of velocity-alignment interactions: the competition between\nself-propulsion and crowding effects plays a minor role in the emergence of\nflocking. However, above the flocking threshold, the system presents a richer\npattern formation scenario than analogous models without alignment interactions\n(Active Brownian Particles) or excluded volume effects (Vicsek-like models).\nDepending on the parameter regime, the structure of the system is characterized\nby either a broad distribution of finite-sized polar clusters or the presence\nof an amorphous, highly fluctuating, large-scale traveling structure which can\ntake a lane-like or band-like form (and usually a hybrid structure which is\nhalfway in between both). We establish a phase diagram that summarizes\ncollective behavior of polar Active Brownian Particles and propose a generic\nmechanism to describe the complexity of the large-scale structures observed in\nsystems of repulsive self-propelled particles."
    },
    {
        "anchor": "Magnetic elastomers as specific soft actuators -- predicting particular\n  modes of deformation from selected configurations of magnetizable inclusions: Amongst the various fascinating types of material behavior featured by\nmagnetic gels and elastomers are magnetostrictive effects. That is,\ndeformations in shape or changes in volume are induced from outside by external\nmagnetic fields. Application of the materials as soft actuators is therefore\nconceivable. Mostly, straight contraction or extension of the materials along a\ncertain direction is discussed and investigated in this context. Here, we\ndemonstrate that various further, different, higher modes of deformation can be\nexcited. To this end, different spatial arrangements of the magnetizable\nparticles enclosed by the soft elastic matrix, which constitute the materials,\nneed to be controlled and realized. We address various different types of\nspatial configurations of the particles and evaluate resulting types of\ndeformation using theoretical tools developed for this purpose. Examples are\nsheet-like arrangements of particles, circular or star-shaped arrangements of\nchain-like aggregates, or actual three-dimensional star-like particle\nconfigurations. We hope to stimulate with our work the development of\nexperimental design and engineering methods so that selected spatial particle\narrangements in magnetic gels and elastomers can be put to reality. Overall, we\nin this way wish to promote the transfer of these promising class of materials\nto real-world applications.",
        "positive": "Leak-rate of seals: comparison of theory with experiment: Seals are extremely useful devices to prevent fluid leakage. We present\nexperimental results for the leak-rate of rubber seals, and compare the results\nto a novel theory, which is based on percolation theory and a recently\ndeveloped contact mechanics theory. We find good agreement between theory and\nexperiment."
    },
    {
        "anchor": "Role of vibrations in the jamming and unjamming of grains discharging\n  from a silo: We present experimental results of the jamming of non-cohesive particles\ndischarged from a flat bottomed silo subjected to vertical vibration. When the\nexit orifice is only a few grain diameter wide, the flow can be arrested due to\nthe formation of blocking arches. Hence, an external excitation is needed to\nresume the flow. The use of a continuous gentle vibration is a usual technique\nto ease the flow in such situations. Even though jamming is less frequent, it\nis still an issue in vibrated silos. There are, in principle, two possible\nmechanisms through which vibrations may facilitate the flow: (i) a decrease in\nthe probability of the formation of blocking arches, and (ii) the breakage of\nblocking arches once they have been formed. By measuring the time intervals\ninside an avalanche during which no particles flow through the outlet, we are\nable to estimate the probability of breaking a blocking arch by vibrations. The\nresult agrees with the prediction of a bivariate probabilistic model in which\nthe formation of blocking arches is equally probable in vibrated and\nnon-vibrated silos. This indicates that the second aforementioned mechanism is\nthe main responsible for improving the flowability in gently vibrated silos.",
        "positive": "Active Refrigerators Powered by Inertia: We present the operational principle for a refrigerator which uses inertial\neffects in active Brownian particles to locally reduce their (kinetic)\ntemperature by two orders of magnitude below the environmental temperature.\nThis principle exploits the peculiar but so-far unknown shape of the phase\ndiagram of inertial active Brownian particles to initiate motility-induced\nphase separation in the targeted cooling regime only. Remarkably, active\nrefrigerators operate without requiring isolating walls opening the route\ntowards using them to systematically absorb and trap, e.g., toxic substances\nfrom the environment."
    },
    {
        "anchor": "Dynamics of gravity driven three-dimensional thin films on\n  hydrophilic-hydrophobic patterned substrates: We investigate numerically the dynamics of unstable gravity driven\nthree-dimensional thin liquid films on hydrophilic-hydrophobic patterned\nsubstrates of longitudinal stripes and checkerboard arrangements. The thin film\ncan be guided preferentially on hydrophilic longitudinal stripes, while fingers\ndevelop on adjacent hydrophobic stripes if their width is large enough. On\ncheckerboard patterns, the film fingering occurs on hydrophobic domains, while\nlateral spreading is favoured on hydrophilic domains, providing a mechanism to\ntune the growth rate of the film. By means of kinematical arguments, we\nquantitatively predict the growth rate of the contact line on checkerboard\narrangements, providing a first step towards potential techniques that control\nthin film growth in experimental setups.",
        "positive": "An improved dissipative coupling scheme for a system of Molecular\n  Dynamics particles interacting with a Lattice Boltzmann fluid: We consider the dissipative coupling between a stochastic Lattice Boltzmann\n(LB) fluid and a particle-based Molecular Dynamics (MD) system, as it was first\nintroduced by Ahlrichs and D\\\"unweg (J. Chem. Phys. 111 (1999) 8225). The fluid\nvelocity at the position of a particle is determined by interpolation, such\nthat a Stokes friction force gives rise to an exchange of momentum between the\nparticle and the surrounding fluid nodes. For efficiency reasons, the LB time\nstep is chosen as a multiple of the MD time step, such that the MD system is\nupdated more frequently than the LB fluid. In this situation, there are\ndifferent ways to implement the coupling: Either the fluid velocity at the\nsurrounding nodes is only updated every LB time step, or it is updated every MD\nstep. It is demonstrated that the latter choice, which enforces momentum\nconservation on a significantly shorter time scale, is clearly superior in\nterms of stability and accuracy, and nevertheless only marginally slower in\nterms of execution speed. The second variant is therefore the recommended\nimplementation."
    },
    {
        "anchor": "A brief critique of the Adam-Gibbs entropy model: This paper critically reviews the entropy model proposed by Adam and Gibbs in\n1965 for explaining the dramatic temperature dependence of glass-forming\nliquids' average relaxation time, one of the most influential models during the\nlast three decades. We discuss the Adam-Gibbs model's theoretical bases as well\nas the reported experimental model confirmations; in the process of doing this\na number of problems with the model are identified.",
        "positive": "Kinetics of HEX-BCC Transition in a Triblock Copolymer in a Selective\n  Solvent: Time Resolved Small Angle X-ray Scattering Measurements and Model\n  Calculations: Time-resolved small angle x-ray scattering (SAXS) was used to examine the\nkinetics of the transition from HEX cylinders to BCC spheres at various\ntemperatures in poly(styrene-b- ethylene-co-butylene-b-styrene) (SEBS) in\nmineral oil, a selective solvent for the middle EB block. Temperature-ramp SAXS\nand rheology measurements show the HEX to BCC order-order transition (OOT) at\n~127 oC and order-disorder transition (ODT) at ~180 oC. We also observed the\nmetastability limit of HEX in BCC with a spinodal temperature, Ts ~ 150 oC. The\nOOT exhibits 3 stages and occurs via a nucleation and growth mechanism when the\nfinal temperature Tf < Ts. Spinodal decomposition in a continuous ordering\nsystem was seen when Ts< Tf < TODT. We observed that HEX cylinders transform to\ndisordered spheres via a transient BCC state. We develop a geometrical model of\ncoupled anisotropic fluctuations and calculate the scattering which shows very\ngood agreement with the SAXS data. The splitting of the primary peak into two\npeaks when the cylinder spacing and modulation wavelength are incommensurate\npredicted by the model is confirmed by analysis of the SAXS data."
    },
    {
        "anchor": "Embryo as an active granular fluid: stress-coordinated cellular\n  constriction chains: Mechanical stress plays an intricate role in gene expression in individual\ncells and sculpting of developing tissues. However, systematic methods of\nstudying how mechanical stress and feedback help to harmonize cellular\nactivities within a tissue have yet to be developed. Motivated by our\nobservation of the cellular constriction chains (CCCs) during the initial phase\nof ventral furrow formation in the Drosophila melanogaster embryo, we propose\nan active granular fluid (AGF) model that provides valuable insights into\ncellular coordination in the apical constriction process. In our model, cells\nare treated as circular particles connected by a predefined force network, and\nthey undergo a random constriction process in which the particle constriction\nprobability P is a function of the stress exerted on the particle by its\nneighbors. We find that when P favors tensile stress, constricted particles\ntend to form chain-like structures. In contrast, constricted particles tend to\nform compact clusters when P favors compression. A remarkable similarity of\nconstricted-particle chains and CCCs observed in vivo provides indirect\nevidence that tensile-stress feedback coordinates the apical constriction\nactivity. We expect that our particle-based AGF model will be useful in\nanalyzing mechanical feedback effects in a wide variety of morphogenesis and\norganogenesis phenomena.",
        "positive": "On the cooperativity of association and reference energy scales in\n  thermodynamic perturbation theory: Equations of state for hydrogen bonding fluids are typically described by two\nenergy scales. A short range highly directional hydrogen bond energy scale, as\nwell as a reference energy scale which accounts for dispersion and\norientationally averaged multi-pole attractions. These energy scales are always\ntreated independently. In recent years, extensive first principles quantum\nmechanics calculations on small water clusters have shown that both hydrogen\nbond and reference energy scales depend on the number of incident hydrogen\nbonds of the water molecule. In this work we propose a new methodology to\ncouple the reference energy scale to the degree of hydrogen bonding in the\nfluid. We demonstrate the utility of the new approach by showing that it gives\nimproved predictions of water-hydrocarbon mutual solubilities."
    },
    {
        "anchor": "Osmotic buckling of spherical capsules: We study the buckling of elastic spherical shells under osmotic pressure with\nthe osmolyte concentration of the exterior solution as control parameter. We\ncompare our results for the bifurcation behavior with results for buckling\nunder mechanical pressure control, that is, with an empty capsule interior. We\nfind striking differences for the buckling states between osmotic and\nmechanical buckling. Mechanical pressure control always leads to fully\ncollapsed states with opposite sides in contact, whereas uncollapsed states\nwith a single finite dimple are generic for osmotic pressure control. For\nsufficiently large interior osmolyte concentrations, osmotic pressure control\nis qualititatively similar to buckling under volume control with the volume\nprescribed by the osmolyte concentrations inside and outside the shell. We\npresent a quantitative theory which also captures the influence of shell\nelasticity on the relation between osmotic pressure and volume. These findings\nare relevant for the control of buckled shapes in applications. We show how the\nosmolyte concentration can be used to control the volume of buckled shells. An\naccurate analytic formula is derived for the relation between the osmotic\npressure, the elastic moduli and the volume of buckled capsules. This also\nallows to use elastic capsules as osmotic pressure sensors or to deduce elastic\nproperties and the internal osmolyte concentration from shape changes in\nresponse to osmotic pressure changes. We apply our findings to published\nexperimental data on polyelectrolyte capsules.",
        "positive": "Stabilization of charged and neutral colloids in salty mixtures: We present a mechanism for the stabilization of colloids in liquid mixtures\nwithout use of surfactants or polymers. When a suitable salt is added to a\nsolvent mixture, the coupling of the colloid's surface chemistry and the\npreferential solvation of ions leads to a repulsive force between colloids that\ncan overcome van der Waals attraction. This repulsive force is substantial in a\nlarge range of temperatures, mixture composition and salt concentrations. The\nincreased repulsion due to addition of salt occurs even for charged colloids.\nThis mechanism may be useful in experimental situations where steric\nstabilization with surfactants or polymers is undesired."
    },
    {
        "anchor": "Using mutual information to measure order in model glass-formers: Whether or not there is growing static order accompanying the dynamical\nheterogeneity and increasing relaxation times seen in glassy systems is a\nmatter of dispute. An obstacle to resolving this issue is that the order is\nexpected to be amorphous and so not amenable to simple order parameters. We use\nmutual information to provide a general measurement of order that is sensitive\nto multi-particle correlations. We apply this to two glass-forming systems (2D\nbinary mixtures of hard disks with different size ratios to give varying\namounts of hexatic order) and show that there is little growth of amorphous\norder in the system without crystalline order. In both cases we measure the\ndynamical length with a four-point correlation function and find that it\nincreases significantly faster than the static lengths in the system as density\nis increased. We further show that we can recover the known scaling of the\ndynamic correlation length in a kinetically constrained model, the 2-TLG.",
        "positive": "Droplet detachment and bead formation in visco-elastic fluids: The presence of a very small amount of high molecular weight polymer\nsignificantly delays the pinch-off singularity of a drop of water falling from\na faucet, and leads to the formation of a long-lived cylindrical filament. In\nthis paper we present experiments, numerical simulations, and theory which\nexamines the pinch-off process in the presence of polymers. The numerical\nsimulations are found to be in excellent agreement with experiment. As a test\ncase, we establish the conditions under which a small bead remains on the\nfilament; we find that this is due to the asymmetry induced by the self-similar\npinch-off of the droplet."
    },
    {
        "anchor": "Solid domains in lipid vesicles and scars: The free energy of a crystalline domain coexisting with a liquid phase on a\nspherical vesicle may be approximated by an elastic or stretching energy and a\nline tension term. The stretching energy generally grows as the area of the\ndomain, while the line tension term grows with its perimeter. We show that if\nthe crystalline domain contains defect arrays consisting of finite length grain\nboundaries of dislocations (scars) the stretching energy grows linearly with a\ncharacteristic length of the crystalline domain. We show that this result is\ncritical to understand the existence of solid domains in lipid-bilayers in the\nstrongly segregated two phase region even for small relative area coverages.\nThe domains evolve from caps to stripes that become thinner as the line tension\nis decreased. We also discuss the implications of the results for other\nexperimental systems and for the general problem that consists in finding the\nground state of a very large number of particles constrained to move on a fixed\ngeometry and interacting with an isotropic potential.",
        "positive": "Characterization of the Soluble Nanoparticles Formed through Coulombic\n  Interaction of Bovine Serum Albumin with Anionic Graft Copolymers at Low pH: A static light scattering (SLS) study of bovine serum albumin (BSA) mixtures\nwith two anionic graft copolymers of poly (sodium acrylate-co-sodium\n2-acrylamido-2-methyl-1-propanesulphonate)-graft-poly (N,\nN-dimethylacrylamide), with a high composition in poly (N,\nN-dimethylacrylamide) (PDMAM) side chains, revealed the formation of oppositely\ncharged complexes, at pH lower than 4.9, the isoelectric point of BSA. The\ncore-corona nanoparticles formed at pH = 3.00, were characterized. Their\nmolecular weight and radius of gyration were determined by SLS, while their\nhydrodynamic radius was determined by dynamic light scattering. Small angle\nneutron scattering measurements were used to determine the radius of the\ninsoluble complexes, comprising the core of the particles. The values obtained\nindicated that their size and aggregation number of the nanoparticles, were\nsmaller when the content of the graft copolymers in neutral PDMAM side chains\nwas higher. Such particles should be interesting drug delivery candidates, if\nthe gastrointestinal tract was to be used."
    },
    {
        "anchor": "Axial collective excitations of a degenerate Fermi gas in the BEC to\n  unitarity crossover: We show that, with reasonable hypotheses leading to a simple modeling,a link\ncan be obtained from experiments on the axial low frequency collective modes\nbetween the molecular scattering length $a_M$ and the energy parameter $\\xi\n\\equiv 1 + \\beta$ of the gas at the unitarity limit. We also point out that, in\norder to reach the range where the features of the Bose limit can be clearly\nseen, experiments have to go to more dilute situations than have been achieved\npresently.",
        "positive": "Equilibrium Phase Behavior and Maximally Random Jammed State of\n  Truncated Tetrahedra: Systems of hard nonspherical particles exhibit a variety of stable phases\nwith different degrees of translational and orientational order, including\nisotropic liquid, solid crystal, rotator and a variety of liquid crystal\nphases. In this paper, we employ a Monte Carlo implementation of the\nadaptive-shrinking-cell (ASC) numerical scheme and free-energy calculations to\nascertain with high precision the equilibrium phase behavior of systems of\ncongruent Archimedean truncated tetrahedra over the entire range of possible\ndensities up to the maximal nearly space-filling density. In particular, we\nfind that the system undergoes two first-order phase transitions as the density\nincreases: first a liquid-solid transition and then a solid-solid transition.\nThe isotropic liquid phase coexists with the Conway-Torquato (CT) crystal phase\nat intermediate densities. At higher densities, we find that the CT phase\nundergoes another first-order phase transition to one associated with the\ndensest-known crystal. We find no evidence for stable rotator (or plastic) or\nnematic phases. We also generate the maximally random jammed (MRJ) packings of\ntruncated tetrahedra, which may be regarded to be the glassy end state of a\nrapid compression of the liquid. We find that such MRJ packings are\nhyperuniform with an average packing fraction of 0.770, which is considerably\nlarger than the corresponding value for identical spheres (about 0.64). We\nconclude with some simple observations concerning what types of phase\ntransitions might be expected in general hard-particle systems based on the\nparticle shape and which would be good glass formers."
    },
    {
        "anchor": "A simple patchy colloid model for the phase behavior of lysozyme\n  dispersions: We propose a minimal model for spherical proteins with aeolotopic pair\ninteractions to describe the equilibrium phase behavior of lysozyme. The\nrepulsive screened Coulomb interactions between the particles are taken into\naccount assuming that the net charges are smeared out homogeneously over the\nspherical protein surfaces. We incorporate attractive surface patches, with the\ninteractions between patches on different spheres modeled by an attractive\nYukawa potential. The parameters entering the attractive Yukawa potential part\nare determined using information on the experimentally accessed gas-liquid-like\ncritical point. The Helmholtz free energy of the fluid and solid phases is\ncalculated using second-order thermodynamic perturbation theory. Our\npredictions for the solubility curve are in fair agreement with experimental\ndata. In addition, we present new experimental data for the gas-liquid\ncoexistence curves at various salt concentrations and compare these with our\nmodel calculations. In agreement with earlier findings, we observe that the\nstrength and the range of the attractive potential part only weakly depend on\nthe salt content.",
        "positive": "Straightening of Thermal Fluctuations in Semi-Flexible Polymers by\n  Applied Tension: We investigate the propagation of a suddenly applied tension along a\nthermally excited semi-flexible polymer using analytical approximations,\nscaling arguments and numerical simulation. This problem is inherently\nnon-linear. We find sub-diffusive propagation with a dynamical exponent of 1/4.\nBy generalizing the internal elasticity, we show that tense strings exhibit\nqualitatively different tension profiles and propagation with an exponent of\n1/2."
    },
    {
        "anchor": "Piling and avalanches of magnetized particles: We performed computer simulations based on a two-dimensional Distinct Element\nMethod to study granular systems of magnetized spherical particles. We measured\nthe angle of repose and the surface roughness of particle piles, and we studied\nthe effect of magnetization on avalanching. We report linear dependence of both\nangle of repose and surface roughness on the ratio $f$ of the magnetic dipole\ninteraction and the gravitational force (\\emph{interparticle force ratio}).\nThere is a difference in avalanche formation at small and at large\ninterparticle force ratios. The transition is at $f_c \\approx 7$. For $f < f_c$\nthe particles forming the avalanches leave the system in a quasi-continuous\ngranular flow (\\emph{granular regime}), while for $f > f_c$ the avalanches are\nformed by long particle clusters (\\emph{correlated regime}). The transition is\nnot sharp. We give plausible estimates for $f_c$ based on stability criteria.",
        "positive": "Unfolding designable structures: Among an infinite number of possible folds, nature has chosen only about 1000\ndistinct folds to form protein structures. Theoretical studies suggest that\nselected folds are intrinsically more designable than others; these selected\nfolds are unusually stable, a property called the designability principle. In\nthis paper we use the 2D hydrophobic-polar lattice model to classify structures\naccording to their designability, and Langevin dynamics to account for their\ntime evolution. We demonstrate that, among all possible folds, the more\ndesignable ones are easier to unfold due to their large number of surface-core\nbonds."
    },
    {
        "anchor": "Fokker-Planck equation with variable diffusion coefficient in the\n  Stratonovich approach: We consider the Langevin equation with multiplicative noise term which\ndepends on time and space. The corresponding Fokker-Planck equation in\nStratonovich approach is investigated. Its formal solution is obtained for an\narbitrary multiplicative noise term given by $g(x,t)=D(x)T(t)$, and the\nbehaviors of probability distributions, for some specific functions of $D(x)$%\n, are analyzed. In particular, for $D(x)\\sim | x| ^{-\\theta /2}$, the physical\nsolutions for the probability distribution in the Ito, Stratonovich and\npostpoint discretization approaches can be obtained and analyzed.",
        "positive": "The role of tumbling frequency and persistence in optimal run-and-tumble\n  chemotaxis: One of simplest examples of navigation found in nature is run-and-tumble\nchemotaxis. Tumbles reorient cells randomly, and cells can drift toward\nattractants or away from repellents by biasing the frequency of these events.\nThe post-tumble swimming directions are typically correlated with those prior,\nas measured by the variance of the reorientation angle distribution. This\nvariance can range from large, in the case of bacteria, to so small that tumble\nevents are imperceptible, as observed in choanoflagellates. This raises the\nquestion of optimality: why is such a range of persistence observed in nature?\nHere we study persistent run-and-tumble dynamics, focusing first on the\noptimisation of the linearised chemotactic response within the two-dimensional\nparameter space of tumble frequency and angular persistence. Although an\noptimal persistence does exist for a given tumble frequency, in the full\nparameter space there is a continuum of optimal solutions. Introducing finite\ntumble times that depend on the persistence can change this picture,\nilluminating one possible method for selecting tumble persistence based on\nspecies-specific reorientation dynamics. Moving beyond linear theory we find\nthat optimal chemotactic strengths exist, and that these maximise reaction when\nswimming in a wrong direction, but have little or no reaction when swimming\nwith even the slightest projection along the chemoattractant gradient."
    },
    {
        "anchor": "Origin of Unusually High Rigidity in Selected Helical Coil Structures: Using continuum elasticity theory, we describe the elastic behavior of\nhelical coils with an asymmetric double-helix structure and identify\nconditions, under which they become very rigid. Theoretical insight gained for\nmacro-structures including a stretched telephone cord and an unsupported\nhelical staircase is universal and of interest for the elastic behavior of\nhelical structures on the micro- and nanometer scale.",
        "positive": "A perturbation density functional theory for the competition between\n  inter and intramolecular association: Using the framework of Wertheim's thermodynamic perturbation theory we\ndevelop the first density functional theory which accounts for intramolecular\nassociation in chain molecules. To test the theory new Monte Carlo simulations\nare performed at a fluid solid interface for a 4 segment chain which can both\nintra and intermolecularly associate. The theory and simulation results are\nfound to be in excellent agreement. It is shown that the inclusion of\nintramolecular association can have profound effects on interfacial properties\nsuch as interfacial tension and the partition coefficient."
    },
    {
        "anchor": "Sedimentation of pairs of hydrodynamically interacting semiflexible\n  filaments: We describe the effect of hydrodynamic interactions in the sedimentation of a\npair of inextensible semiflexible filaments under a uniform constant force at\nlow Reynolds numbers. We have analyzed the different regimes and the morphology\nof such polymers in simple geometries, which allow us to highlight the\npeculiarities of the interplay between elastic and hydrodynamic stresses.\nCooperative and symmetry breaking effects associated to the geometry of the\nfibers gives rise to characteristic motion which give them distinct properties\nfrom rigid and elastic filaments.",
        "positive": "Short-Time Elasticity of Polymer Melts: Tobolsky Conjecture and\n  Heterogeneous Local Stiffness: An extended Molecular-Dynamics study of the short-time \"glassy\" elasticity\nexhibited by a polymer melt of linear fully-flexible chains above the glass\ntransition is presented. The focus is on the infinite-frequency shear modulus\n$G_\\infty$ manifested in the picosecond time scale and the relaxed plateau\n$G_p$ reached at later times and terminated by the structural relaxation. The\nlocal stiffness of the interactions with the first neighbours of each monomer\nexhibits marked distribution with average value given by $G_\\infty$. In\nparticular, the neighbourhood of the end monomers of each chain are softer than\nthe inner monomers, so that $G_\\infty$ increases with the chain length. $G_p$\nis not affected by the chain length and is largely set by the non-bonding\ninteractions, thus confirming for polymer melts the conjecture formulated by\nTobolsky for glassy polymers."
    },
    {
        "anchor": "A parameter-free, solid-angle based, nearest-neighbor algorithm: We propose a parameter-free algorithm for the identification of nearest\nneighbors. The algorithm is very easy to use and has a number of advantages\nover existing algorithms to identify nearest- neighbors. This solid-angle based\nnearest-neighbor algorithm (SANN) attributes to each possible neighbor a solid\nangle and determines the cutoff radius by the requirement that the sum of the\nsolid angles is 4{\\pi}. The algorithm can be used to analyze 3D images, both\nfrom experiments as well as theory, and as the algorithm has a low\ncomputational cost, it can also be used \"on the fly\" in simulations. In this\npaper, we describe the SANN algorithm, discuss its properties, and compare it\nto both a fixed-distance cutoff algorithm and to a Voronoi construction by\nanalyzing its behavior in bulk phases of systems of carbon atoms, Lennard-Jones\nparticles and hard spheres as well as in Lennard-Jones systems with\nliquid-crystal and liquid-vapor interfaces.",
        "positive": "Polarization gratings spontaneously formed by the helical Twist-Bend\n  Nematic phase: Spontaneous formation of polarization gratings by liquid crystals made of\nbent dimeric molecules is reported. The grating is formed within the\ntemperature range of the twist bend modulated nematic phase, NTB, without the\nnecessity to pattern the cell surfaces, therefore the modulated nematic phase\nis a promising candidate for low-cost modulators and beam steering devices, the\npolarization properties of which can be tuned by temperature. In addition, the\nstudy of the diffracted light properties turns out to be a sensitive measuring\ntechnique for determination of the 3D spatial variation of the optic axis in\nthe cell."
    },
    {
        "anchor": "Dynamics of Network Fluids: Network fluids are structured fluids consisting of chains and branches. They\nare characterized by unusual physical properties, such as, exotic bulk phase\ndiagrams, interfacial roughening and wetting transitions, and equilibrium and\nnonequilibrium gels. Here, we provide an overview of a selection of their\nequilibrium and dynamical properties. Recent research efforts towards bridging\nequilibrium and non-equilibrium studies are discussed, as well as several open\nquestions.",
        "positive": "Self-assembly scenarios of patchy colloidal particles: The rapid progress in precisely designing the surface decoration of patchy\ncolloidal particles offers a new, yet unexperienced freedom to create building\nentities for larger, more complex structures in soft matter systems. However,\nit is extremely difficult to predict the large variety of ordered equilibrium\nstructures that these particles are able to undergo under the variation of\nexternal parameters, such as temperature or pressure. Here we show that, by a\nnovel combination of two theoretical tools, it is indeed possible to predict\nthe self-assembly scenario of patchy colloidal particles: on one hand, a\nreliable and efficient optimization tool based on ideas of evolutionary\nalgorithms helps to identify the ordered equilibrium structures to be expected\nat T = 0; on the other hand, suitable simulation techniques allow to estimate\nvia free energy calculations the phase diagram at finite temperature. With\nthese powerful approaches we are able to identify the broad variety of emerging\nself-assembly scenarios for spherical colloids decorated by four patches and we\ninvestigate and discuss the stability of the crystal structures on modifying in\na controlled way the tetrahedral arrangement of the patches."
    },
    {
        "anchor": "Non-ideal behavior of intramolecular structure factor of dilute polymers\n  in a theta solvent: We study the configurational properties of single polymers in a theta solvent\nby Monte Carlo simulation of the bond fluctuation model. The intramolecular\nstructure factor at the theta point is found to be distinctively different from\nthat of the ideal chain. The structure factor shows a hump around $q\\sim 5/R_g$\nand a dip around $q\\sim 10/R_g$ in the Kratky plot with $R_g$ being the radius\nof gyration. This feature is apparently similar to that in a melt. The\ntheoretical expression by the simple perturbation expansion to the first order\nin terms of the Mayer function can be fitted to the obtained structure factor\nquite well, but the second virial coefficient cannot be set to zero.",
        "positive": "Coffee-stain growth dynamics on dry and wet surfaces: The drying of a drop containing particles often results in the accumulation\nof the particles at the contact line. In this work, we investigate the drying\nof an aqueous colloidal drop surrounded by a hydrogel that is also evaporating.\nWe combine theoretical and experimental studies to understand how the\nsurrounding vapor concentration affects the particle deposit during the\nconstant radius evaporation mode. In addition to the common case of evaporation\non an otherwise dry surface, we show that in a configuration where liquid is\nevaporating from a flat surface around the drop, the singularity of the\nevaporative flux at the contact line is suppressed and the drop evaporation is\nhomogeneous. For both conditions, we derive the velocity field and we establish\nthe temporal evolution of the number of particles accumulated at the contact\nline. We predict the growth dynamics of the stain and the drying timescales.\nThus, dry and wet conditions are compared with experimental results and we\nhighlight that only the dynamics is modified by the evaporation conditions, not\nthe final accumulation at the contact line."
    },
    {
        "anchor": "Atomistic simulations of nematic phases formed by cyano-biphenyl dimers: Molecular dynamics simulations of selected members of the cyano-biphenyl\nseries of dimers (CBnCB) have been set up using atomistic detail interactions\namong intermolecular pairs of united atoms and allowing fully for the\nflexibility of the spacer chain. Detailed results are presented for the CB7CB\ndimers, showing an isotropic fluid phase and two nematic phases. The positional\nand orientational correlation functions extracted from the simulations are used\nto elucidate the structure of the low-temperature nematic phase. Polar\nmolecular ordering is clearly identified along a direction undergoing helical\ntwisting at right angles to the helical axis, with a constant pitch of about of\n8nm. The local ordering of the various molecular segments is calculated and\nfound to be in excellent agreement with experimental NMR measurements. Key\nfindings of the simulation are shown to be correctly predicted by the\ntheoretical model of the polar-twisted nematic (NPT) phase [A.G. Vanakaras,\nD.J. Photinos, Soft Matter. 12 (2016) 2208-2220]. The complete failure of the\nusual twist bend model (NTB) to account for these findings is demonstrated.",
        "positive": "Bose-Einstein-Young condensates: We demonstrate a possibility to create a new state of ultracold atoms which\nwe call a Bose-Einstein-Young condensate. Atoms are supposed to be in different\nhyperfine state of the same isotope. The wave function of such a state,\nalthough totally symmetric with respect to simultaneous permutation of\nco-ordinates and spins of any pair of atoms, has more complicated structure\nthan a simple product of totally symmetric co-ordinate and spin parts. Its\nproperties with respect to permutations of only co-ordinates or only spins are\ncharacterized by a particular Young diagram, a symbol denoting an irreducible\nrepresentation of the permutation group."
    },
    {
        "anchor": "Concentration fluctuations and phase transitions in coupled modulated\n  bilayers: We consider the formation of finite-size domains in lipid bilayers consisting\nof saturated and hybrid lipids. First, we describe a monolayer model that\nincludes a coupling between a compositional scalar field and a two-dimensional\nvectorial order-parameter. Such a coupling yields an effective two-dimensional\nmicroemulsion free-energy for the lipid monolayer, and its characteristic\nlength of compositional modulations can be considered as the origin of\nfinite-size domains in biological membranes. Next, we consider a coupled\nbilayer composed of two modulated monolayers, and discuss the static and\ndynamic properties of concentration fluctuations above the transition\ntemperature. We also investigate the micro-phase separation below the\ntransition temperature, and compare the micro-phase separated structures with\nstatics and dynamics of concentration fluctuations above the transition.",
        "positive": "Time-resolved microstructural changes in large amplitude oscillatory\n  shear of model single and double component soft gels: Soft particulate gels can reversibly yield when sufficient deformation is\napplied, and the characteristics of this transition can be enhanced or limited\nby designing hybrid hydrogel composites. While the microscopic dynamics and\nmacroscopic rheology of these systems have been studied separately in detail,\nthe development of direct connections between the two has been difficult,\nparticularly with regard to the non-linear rheology. To bridge this gap, we\nperform a series of large amplitude oscillatory shear (LAOS) numerical\nmeasurements on model soft particulate gels at different volume fractions using\ncoarse-grained molecular dynamics simulations. We first study a particulate\nnetwork with local bending stiffness and then we combine it with a second\ncomponent that can provide additional crosslinking to obtain two-component\nnetworks. Through the sequence of physical processes (SPP) framework we define\ntime-resolved dynamic moduli and, by tracking the changes in these moduli\nthrough the period, we can distinguish transitions in the material behavior as\na function of time. This approach helps us establish the microsopic origin of\nthe non-linear rheology by connecting the changes in dynamic moduli to the\ncorresponding microstructural changes during the deformation including the\nnon-affine displacement of particles, and the breakage, formation, and\norientation of bonds."
    },
    {
        "anchor": "Collective Dynamics of Lipid Membranes studied by Inelastic Neutron\n  Scattering: We have studied the collective short wavelength dynamics in deuterated DMPC\nbilayers by inelastic neutron scattering. The corresponding dispersion relation\n$\\hbar\\omega$(Q) is presented for the gel and fluid phase of this model system.\nThe temperature dependence of the inelastic excitations indicates a phase\ncoexistence between the two phases over a broad range and leads to a different\nassignment of excitations than that reported in a preceding inelastic x-ray\nscattering study [Phys. Rev. Lett. {\\bf 86}, 740 (2001)]. As a consequence, we\nfind that the minimum in the dispersion relation is actually deeper in the gel\nthan in the fluid phase. Finally, we can clearly identify an additional\nnon-dispersive (optical) mode predicted by Molecular Dynamics (MD) simulations\n[Phys. Rev. Lett. {\\bf 87}, 238101 (2001)].",
        "positive": "Dynamical behavior of a complex fluid near an out-of-equilibrium\n  transition: approaching simple rheological chaos: We report here an extensive study of sustained oscillations of the viscosity\nof a complex fluid near an out-of-equilibrium transition. Using well defined\nprotocols, we perform rheological measurements of the onion texture near a\nlayering transition in a Couette flow. This complex fluid exhibits sustained\noscillations of the viscosity, on a large time scale (500s) at controlled\nstress. These oscillations are directly correlated to an oscillating\nmicrostrutural change of the texture of the fluid. We observe a great diversity\nof dynamical behavior and we show that there is a coupling with spatial effects\nin the gradient v direction. This is in agreement with a carefull analysis of\nthe temporal series of the viscosity with the dynamical system theory. This\nanalysis indicates that the observed dynamical responses do not strictly\ncorrespond to 3-dimensional chaotic states, probably because some\nspatio-temporal effects are present and are likely to play an important role."
    },
    {
        "anchor": "Phase behavior and structure of model colloid-polymer mixtures confined\n  between two parallel planar walls: Using Gibbs ensemble Monte Carlo simulations and density functional theory we\ninvestigate the fluid-fluid demixing transition in inhomogeneous\ncolloid-polymer mixtures confined between two parallel plates with separation\ndistances between one and ten colloid diameters covering the complete range\nfrom quasi two-dimensional to bulk-like behavior. We use the\nAsakura-Oosawa-Vrij model in which colloid-colloid and colloid-polymer\ninteractions are hard-sphere like, whilst the pair potential between polymers\nvanishes. Two different types of confinement induced by a pair of parallel\nwalls are considered, namely either through two hard walls or through two\nsemi-permeable walls that repel colloids but allow polymers to freely\npenetrate. For hard (semi-permeable) walls we find that the capillary binodal\nis shifted towards higher (lower) polymer fugacities and lower (higher) colloid\nfugacities as compared to the bulk binodal; this implies capillary condensation\n(evaporation) of the colloidal liquid phase in the slit. A macroscopic\ntreatment is provided by a novel symmetric Kelvin equation for general binary\nmixtures, based on the proximity in chemical potentials of statepoints at\ncapillary coexistence and the reference bulk coexistence. Results for capillary\nbinodals compare well with those obtained from the classic version of the\nKelvin equation due to Evans and Marini Bettolo Marconi [J. Chem. Phys. 86,\n7138 (1987)], and are quantitatively accurate away from the fluid-fluid\ncritical point, even at small wall separations. For hard walls the density\nprofiles of polymers and colloids inside the slit display oscillations due to\npacking effects for all statepoints. For semi-permeable walls either similar\nstructuring or flat profiles are found, depending on the statepoint considered.",
        "positive": "Thermal collapse of a granular gas under gravity: Free cooling of a gas of inelastically colliding hard spheres represents a\ncentral paradigm of kinetic theory of granular gases. At zero gravity the\ntemperature of a freely cooling homogeneous granular gas follows a power law in\ntime. How does gravity, which brings inhomogeneity, affect the cooling? We\ncombine molecular dynamics simulations, a numerical solution of hydrodynamic\nequations and an analytic theory to show that a granular gas cooling under\ngravity undergoes thermal collapse: it cools down to zero temperature and\ncondenses on the bottom of the container in a finite time."
    },
    {
        "anchor": "A statistical model of fracture for a 2D hexagonal mesh: the Cell\n  Network Model of Fracture for the bamboo Guadua angustifolia: A 2D, hexagonal in geometry, statistical model of fracture is proposed. The\nmodel is based on the drying fracture process of the bamboo Guadua\nangustifolia. A network of flexible cells are joined by brittle junctures of\ndifferent Young moduli that break at a fixed threshold in tensile force. The\nsystem is solved by means of the Finite Element Method (FEM). The distribution\nof avalanche breakings exhibits a power law with exponent -2.93(9), in\nagreement with the random fuse model.",
        "positive": "Characterizing Complex Particle Morphologies Through Shape Matching:\n  Descriptors, Applications, and Algorithms: Many standard structural quantities, such as order parameters and correlation\nfunctions, exist for common condensed matter systems, such as spherical and\nrod-like particles. However, these structural quantities are often insufficient\nfor characterizing the unique and highly complex structures often encountered\nin the emerging field of nano and microscale self-assembly, or other\ndisciplines involving complex structures such as computational biology.\nComputer science algorithms known as \"shape matching\" methods pose a unique\nsolution to this problem by providing robust metrics for quantifying the\nsimilarity between pairs of arbitrarily complex structures. This pairwise\nmatching operation, either implicitly or explicitly, lies at the heart of most\nstandard structural characterization schemes for particle systems. By\nsubstituting more robust \"shape descriptors\" into these schemes we extend their\napplicability to structures formed from more complex building blocks. Here, we\ndescribe several structural characterization schemes and shape descriptors that\ncan be used to obtain various types of structural information about particle\nsystems. We demonstrate the application of shape matching algorithms to a\nvariety of example problems, for topics including local and global structure\nidentification and classification, automated phase diagram mapping, and the\nconstruction of spatial and temporal correlation functions. The methods are\napplicable to a wide range of systems, both simulated and experimental,\nprovided particle positions are known or can be accurately imaged."
    },
    {
        "anchor": "Modulated phases of nematic liquid crystals induced by tetrahedral order: Recent theoretical research has developed a general framework to understand\ndirector deformations and modulated phases in nematic liquid crystals. In this\nframework, there are four fundamental director deformation modes: twist, bend,\nsplay, and a fourth mode $\\Delta$ related to saddle-splay. The first three of\nthese modes are known to induce modulated phases. Here, we consider modulated\nphases induced by the fourth mode. We develop a theory for tetrahedral order in\nliquid crystals, and show that it couples to the $\\Delta$ mode of director\ndeformation. Because of geometric frustration, the $\\Delta$ mode cannot fill\nspace by itself, but rather must be accompanied by twist or splay. Hence, it\nmay induce a spontaneous cholesteric phase, with either handedness, or a splay\nnematic phase.",
        "positive": "Activity driven orientational order in active nematic liquid crystals on\n  an anisotropic substrate: We investigate the effect of an anisotropic substrate on the turbulent\ndynamics of a simulated two dimensional active nematic. This is introduced as\nan anisotropic friction and an effective anisotropic viscosity, with the\norientation of the anisotropy being defined by the substrate. In this system we\nobserve the emergence of global nematic order of topological defects that is\ncontrolled by the degree of anisotropy in the viscosity and the magnitude of\nthe active stress. No global defect alignment is seen in passive liquid\ncrystals with anisotropic viscosity or friction confirming that ordering is\ndriven by the active stress. We then closely examine the active flow generated\nby a single defect to show that the kinetic energy of the flow is orientation\ndependent, resulting in a torque on the defect to align them with the\nanisotropy in the substrate."
    },
    {
        "anchor": "Active nematics on flat surfaces: from droplet motility and scission to\n  active wetting: We consider the dynamics of active nematics droplets on flat surfaces, based\non the continuum hydrodynamic theory. We investigate a wide range of dynamical\nregimes as a function of the activity and droplet size on surfaces\ncharacterized by strong anchoring and a range of equilibrium contact angles.\nThe activity was found to control a variety of dynamical regimes, including the\nself-propulsion of droplets on surfaces, scission, active wetting and droplet\nevaporation. Furthermore, we found that on a given surface (characterized by\nthe anchoring and the equilibrium contact angle) the dynamical regimes may be\ncontrolled by the active capillary number of suspended droplets. We also found\nthat the active nematics concentration of the droplets varies with the\nactivity, affecting the wetting behaviour weakly but ultimately driving droplet\nevaporation. Our analysis provides a global description of a wide range of\ndynamical regimes reported for active nematics droplets and suggests a unified\ndescription of droplets on surfaces. We discuss the key role of the finite size\nof the droplet and comment on the suppression of these regimes in the infinite\nsize limit, where the active nematics is turbulent at any degree of activity.",
        "positive": "Driving and characterizing nucleation of urea and glycine polymorphs in\n  water: Crystal nucleation is relevant across the domains of fundamental and applied\nsciences. However, in many cases its mechanism remains unclear due to a lack of\ntemporal or spatial resolution. To gain insights to the molecular details of\nnucleation, some form of molecular dynamics simulations is typically performed;\nthese simulations, in turn, are limited by their ability to run long enough to\nsample the nucleation event thoroughly. To overcome the timescale limits in\ntypical molecular dynamics simulations in a manner free of prior human bias,\nhere we employ the machine learning augmented molecular dynamics framework\n``Reweighted Autoencoded Variational Bayes for enhanced sampling (RAVE)\". We\nstudy two molecular systems, urea and glycine in explicit all-atom water, due\nto their enrichment in polymorphic structures and common utility in commercial\napplications. From our simulations, we observe multiple back-and-forth\nliquid-solid transitions of different polymorphs and from these trajectories\ncalculate the polymorph stability relative to the dissolved liquid state. We\nfurther observe that the obtained reaction coordinates and transitions are\nhighly non-classical."
    },
    {
        "anchor": "Volume Phase Transition of Polyelectrolyte Gels: Effects of Ionic Size: Although the volume transition of the polyelectrolyte gel has been studied\nfor decades, little research on the effects of size of the mobile ions has been\nconducted. In the present paper, Tanaka classical theory of polyelectrolyte gel\nis extended to the cases of mobile ions of finite volume. In the salt free\nlimit, the theoretical results show that the discontinuous volume transition of\nthe polyelectrolyte gel will become a continuous one with an increase of the\ncounter-ionic size. An increase in salt concentration can also make the\npolyelectrolyte gel in poor solvent collapse. Poorer solvent is needed to\ntrigger the salt-induced collapse in polyelectrolyte gel with larger mobile\nions than that with smaller ones. The effects of ionic size on the critical\npoints and phase diagram of the volume transition are also discussed. The\ntheoretical results suggest that the swelling behavior of polyelectrolyte gel\nmight be tuned with salt of different volumes.",
        "positive": "Viscoelastic Phase Separation Model for Ternary Polymer Solutions: When a polymer solution undergoes viscoelastic phase separation, the\npolymer-rich phase forms a network-like structure even if it is a minor phase.\nThis unique feature is induced by polymer dynamics, which are constrained by\nthe temporal entanglement of polymer chains. The fundamental mechanisms of\nviscoelastic phase separation have already been elucidated by theory and\nexperiments over the past few decades; however, it is not yet well understood\nhow viscoelastic phase separation occurs in multicomponent polymer solutions.\nHere, we construct a new viscoelastic phase separation model for ternary\npolymer solutions that consist of a polymer, solvent, and nonsolvent. Our\nsimulation results reveal that a network-like structure is formed in the\nternary bulk system through a phase separation mechanism similar to that\nobserved in binary polymer solutions. A difference in dynamics is also found in\nthat the solvent, whose affinity to the polymer is similar to that to the\nnonsolvent, moves freely between the polymer-rich and water-rich phases during\nphase separation. These findings are considered important for understanding the\nphase separation mechanism of ternary mixtures often used in the manufacturing\nof polymeric separation membranes."
    },
    {
        "anchor": "A mathematical finance approach to the stochastic and intermittent\n  viscosity fluctuations in living cells: Here we report on the viscosity of eukaryotic living cells as a function of\nthe time, and on the application of stochastic models to analyze its temporal\nfluctuations. The viscoelastic properties of NIH/3T3 fibroblastic cells are\ninvestigated using an active microrheological technique, where magnetic wires,\nembedded into cells, are being actuated remotely. The data reveal anomalous\ntransient responses characterized by intermittent phases of slow and fast\nrotation, revealing significant fluctuations. The time dependent viscosity is\nanalyzed from a time series perspective by computing the autocorrelation\nfunctions and the variograms, two functions used to describe stochastic\nprocesses in mathematical finance. The resulting analysis gives evidence of a\nsub-diffusive mean-reverting process characterized by an autoregressive\ncoefficient lower than 1. It also shows the existence of specific cellular\ntimes in the ranges 1 - 10 s and 100 - 200 s, not previously disclosed. The\nshorter time is found being related to the internal relaxation time of the\ncytoplasm. To our knowledge, this is the first time that similarities are\nestablished between the properties of time series describing the intracellular\nmetabolism and statistical results from mathematical finance. The current\napproach could be exploited to reveal hidden features from biological complex\nsystems, or determine new biomarkers of cellular metabolism.",
        "positive": "Stress Propagation in Two Dimensional Frictional Granular Matter: The stress profile and reorientation of grains, in response to a point force\napplied to a preloaded two dimensional granular system, are calculated in the\ncontext of a continuum theory that incorporates the texture of the packing.\nWhen high friction prevents slip at the inter-grain contacts, an anisotropic\npacking propagates stress along two peaks which amalgamate into a single peak\nas the packing is disordered into a less anisotropic structure; this single\npeak may be wider or narrower than in the isotropic case, depending on the\npreparation of the packing. At lower frictions, an effective treatment of\nslipping contacts yields sharpened peaks, and ultimately a singular limit in\nwhich stress propagates along straight rays. Recent experiments, as well as\naspects of hyperbolic models, are discussed in light of these results."
    },
    {
        "anchor": "Suppression of coarsening and emergence of oscillatory behavior in a\n  Cahn-Hilliard model with nonvariational coupling: We investigate a generic two-field Cahn-Hilliard model with variational and\nnonvariational coupling. It describes, for instance, passive and active ternary\nmixtures, respectively. Already a linear stability analysis of the homogeneous\nmixed state shows that activity not only allows for the usual large-scale\nstationary (Cahn-Hilliard) instability of the well known passive case but also\nfor small-scale stationary (Turing) and large-scale oscillatory (Hopf)\ninstabilities. In consequence of the Turing instability, activity may\ncompletely suppress the usual coarsening dynamics. In a fully nonlinear\nanalysis we first briefly discuss the passive case before focusing on the\nactive case. Bifurcation diagrams and selected direct time simulations are\npresented that allow us to establish that nonvariational coupling (i) can\npartially or completely suppress coarsening and (ii) may lead to the emergence\nof drifting and oscillatory states. Throughout, we emphasize the relevance of\nconservation laws and related symmetries for the encountered intricate\nbifurcation behavior.",
        "positive": "Polyhedral vesicles: Polyhedral vesicles with a large bending modulus of the membrane such as the\ngel phase lipid membrane were studied using a Brownian dynamics simulation. The\nvesicles exhibit various polyhedral morphologies such as tetrahedron and cube\nshapes. We clarified two types of line defects on the edges of the polyhedrons:\ncracks of both monolayers at the spontaneous curvature of monolayer $C_{\\text\n{0}}<0$, and a crack of the inner monolayer at $C_{\\text {0}}\\ge0$. Around the\nlatter defect, the inner monolayer curves positively. Our results suggested\nthat the polyhedral morphology is controlled by $C_{\\text {0}}$."
    },
    {
        "anchor": "Colloidal stabilization via nanoparticle haloing: We present a detailed numerical study of effective interactions between\nmicron-sized silica spheres, induced by highly charged zirconia nanoparticles.\nIt is demonstrated that the effective interactions are consistent with a\nrecently discovered mechanism for colloidal stabilization. In accordance with\nthe experimental observations, small nanoparticle concentrations induce an\neffective repulsion that counteracts the intrinsic van der Waals attraction\nbetween the colloids and thus stabilizes the suspension. At higher nanoparticle\nconcentrations an attractive potential is recovered, resulting in reentrant\ngelation. Monte Carlo simulations of this highly size-asymmetric mixture are\nmade possible by means of a geometric cluster Monte Carlo algorithm. A\ncomparison is made to results obtained from the Ornstein-Zernike equations with\nthe hypernetted-chain closure.",
        "positive": "Chiral active matter: microscopic `torque dipoles' have more than one\n  hydrodynamic description: Many biological systems, such as bacterial suspensions and actomyosin\nnetworks, form polar liquid crystals. These systems are `active' or\nfar-from-equilibrium, due to local forcing of the solvent by the constituent\nparticles. In many cases the source of activity is chiral; since forcing is\ninternally generated, some sort of `torque dipole' is then present locally. But\nit is not obvious how `torque dipoles' should be encoded in the hydrodynamic\nequations that describe the system at continuum level: different authors have\narrived at contradictory conclusions on this issue. In this work, we resolve\nthe paradox by presenting a careful derivation, from linear irreversible\nthermodynamics, of the general equations of motion of a single-component chiral\nactive fluid with spin degrees of freedom. We find that there is no unique\nhydrodynamic description for such a fluid in the presence of torque dipoles of\na given strength. Instead, at least three different hydrodynamic descriptions\nemerge, depending on whether we decompose each torque dipole as two point\ntorques, two force pairs, or one point torque and one force pair -- where point\ntorques create internal angular momenta of the chiral bodies (spin), whereas\nforce pairs impart centre of mass motion that contributes to fluid velocity. By\nconsidering a general expansion of the Onsager coefficients, we also derive a\nnew shear-elongation parameter and cross-coupling viscosity, which can lead to\nunpredicted phenomena even in passive polar liquid crystals. Finally,\nelimination of the angular variables gives an effective polar hydrodynamics\nwith renormalized active stresses, viscosities and kinetic coefficients.\nRemarkably, this can include a direct contribution of chiral activity to the\nequation of motion for the polar order parameter, which survives even in `dry'\nactive systems where the fluid velocity is set to zero."
    },
    {
        "anchor": "Roughness as a measurement of random disorder: We have studied the quenched random disorder (QRD) effects created by aerosil\ndispersion in octylcyanobiphenyl (8CB) liquid crystal (LC) using Atomic Force\nMicroscopy (AFM) technique. Gelation process in the 8CB+aerosil gels yields a\nQRD network which also changes the surface topography. By increasing the\naerosil concentration, the original smooth pattern of LC sample surfaces is\nsuppressed by creating a fractal aerosil surface effect, these surfaces become\nmore porous, rougher with more and bigger crevices. The dispersed aerosil also\nserves as pinning centers for the liquid crystal molecules. It has been\nobserved that via the diffusion-limited-aggregation process, aerosil\nnano-particles yield a fractal like surface pattern for the less disordered\nsamples. As the aerosil dispersion increases, the surface can be described by\nmore aggregated regions which also introduce more roughness. Using this fact,\nwe have shown that there is a net correlation between the short-ranged x-ray\npeak widths (-the results of previous x-ray diffraction experiments-) and the\ncalculated surface roughness. In other words, we have shown that these QRD gels\ncan also be characterized by their surface roughness values.",
        "positive": "Computational Reverse Engineering Analysis of Scattering Experiments\n  Method for Interpretation of 2D Small-Angle Scattering Profiles (CREASE-2D): Characterization of structural diversity within soft materials is key for\nengineering new materials for various applications. Small-angle scattering\n(SAS) is a widely used characterization technique that provides structural\ninformation in soft materials at varying length scales and typically outputs\nscattered intensity I(q) as a function of the scattered wavevector represented\nby its magnitude q and azimuthal angle {\\theta}. While isotropic structures can\nbe interpreted from azimuthally averaged 1D SAS profile, to understand\nanisotropic spatial arrangements, one has to interpret the 2D SAS profile,\nI(q,{\\theta}). In this paper, we present a new method called CREASE-2D that\ninterprets I(q,{\\theta}) as is and outputs the relevant structural features.\nCREASE-2D is an extension of the 'computational reverse engineering analysis\nfor scatting experiments' (CREASE) method that has been used successfully to\nanalyze 1D SAS profiles for a variety of soft materials. CREASE uses a genetic\nalgorithm for optimization and a surrogate machine learning (ML) model for fast\ncalculation of 1D 'computed' scattering profiles that are then compared to the\nexperimental 1D scattering profiles during optimization. In CREASE-2D, which\ngoes beyond CREASE in interpretting 2D scattering profiles, we use XGBoost as\nthe surrogate ML model to relate structural features to the I(q,{\\theta})\nprofile. The CREASE-2D workflow identifies the structural features whose\ncomputed I(q,{\\theta}) profiles match the input experimental I(q,{\\theta}). We\ntest the performance of CREASE-2D by using as input a variety of in silico 2D\nSAS profiles with known structural features and demonstrate that CREASE-2D\nconverges towards their correct structural features. We expect this method will\nbe valuable for materials' researchers who need direct interpretation of 2D\nscattering profiles to explore structural anisotropy."
    },
    {
        "anchor": "Chemotaxis of cargo-carrying self-propelled particles: Active particles with their characteristic feature of self-propulsion are\nregarded as the simplest models for motility in living systems. The\naccumulation of active particles in low activity regions has led to the general\nbelief that chemotaxis requires additional features and at least a minimal\nability to process information and to control motion. We show that\nself-propelled particles display chemotaxis and move into regions of higher\nactivity, if the particles perform work on passive objects, or cargo, to which\nthey are bound. The origin of this cooperative chemotaxis is the exploration of\nthe activity gradient by the active particle when bound to a load, resulting in\nan average excess force on the load in the direction of higher activity. Using\na minimalistic theoretical model, we capture the most relevant features of\nthese active-passive dimers and in particular we predict the crossover between\nanti-chemotactic and chemotactic behaviour. Moreover we show that merely\nconnecting active particles to chains is sufficient to obtain the crossover\nfrom anti-chemotaxis to chemotaxis with increasing chain length. Such an active\ncomplex is capable of moving up a gradient of activity such as provided by a\ngradient of fuel and to accumulate where the fuel concentration is at its\nmaximum. The observed transition is of significance to proto-forms of life\nenabling them to locate a source of nutrients even in the absence of any\nsupporting sensomotoric apparatus.",
        "positive": "Quasi-Equilibrium Self-Assembly of Small RNA Viruses: We propose a description for the quasi-equilibrium self-assembly of small,\nsingle-stranded (ss) RNA viruses whose capsid proteins (CPs) have flexible,\npositively charged, disordered tails that associate with the negatively charged\nRNA genome molecules. We describe the assembly of such viruses as the interplay\nbetween two coupled phase-transition like events: the formation of the protein\nshell (the capsid) by CPs and the condensation of a large ss viral RNA\nmolecule. Electrostatic repulsion between the CPs competes with attractive\nhydrophobic interactions and attractive interaction between neutralized RNA\nsegments mediated by the tail-groups. An assembly diagram is derived in terms\nof the strength of attractive interactions between CPs and between CPs and the\nRNA molecules. It is compared with the results of recent studies of viral\nassembly. We demonstrate that the conventional theory of self-assembly, which\ndoes describe the assembly of \\textit{empty} capsids, is in general not\napplicable to the self-assembly of RNA-encapsidating virions."
    },
    {
        "anchor": "Kinetics of bond formation in crosslinked gelatin gels: In chemical crosslinking of gelatin solutions, two different time scales\naffect the kinetics of the gel formation in the experiments. We complement the\nexperimental study with Monte Carlo numerical simulations of a lattice model.\nThis approach shows that the two characteristic time scales are related to the\nformation of single bonds crosslinker-chain and of bridges between chains. In\nparticular their ratio turns out to control the kinetics of the gel formation.\nWe discuss the effect of the concentration of chains. Finally our results\nsuggest that, by varying the probability of forming bridges as an independent\nparameter, one can finely tune the kinetics of the gelation via the ratio of\nthe two characteristic times.",
        "positive": "Rheological Analysis and Evaluation of Measurement Techniques for the\n  Curing Polymethylmethacrylate Bone Cement in Vertebroplasty: Vertebroplasty is a minimally invasive surgical procedure used to treat\nvertebral fractures, which conventionally involves injection of a\npolymethylmethacrylate (PMMA) bone cement into the fractured vertebra. A common\nrisk associated with vertebroplasty is that of cement leaking out of the\nvertebra during the injection. This could happen since the flow behaviour of\nthe bone cement is not conventional, but it varies with many factors like\ncuring time, shear rate, and temperature. Therefore, experiments to quantify\nthe cement's flow properties are necessary to be able to understand and\nproperly handle the bone cement. In this study, we aimed to characterize the\nbehaviour of the PMMA bone cement in its curing stages, in order to obtain\nparameters that govern the flow behaviour during injection flow. The\nmeasurements were done using rotational and oscillatory rheometry as well as\nusing a custom-made injetor setup replicating a typical vertebroplasty setting.\nOur results showed that the complex viscoelastic behaviour of the bone cement,\nwhich evolves over a two-phase curing process, can be significantly affected by\ndeformations and temperature. We found that the results from rotational tests\nwere affected by wall slip and \"ridge\"-like formations in the test sample,\nwhich we confirmed visually by microscopical assessment. We also found that the\nCox-Merz rule to be conditionally valid, which impacts the use of oscillatory\ntests to obtain shear-thinning characteristics for the bone cement."
    },
    {
        "anchor": "Fluid transport and mixing by an unsteady microswimmer: We study the fluid drift due to a time-dependent dumbbell model of a\nmicroswimmer. The model captures important aspects of real microswimmers such\nas a time-dependent flagellar motion and a no-slip body. The model consists of\na rigid sphere for the body and a time-dependent moving Stokeslet representing\nthe flagella. We analyze the paths of idealized fluid particles displaced by\nthe swimmer. The simplicity of the model allows some asymptotic calculations\nvery near and far away from the swimmer. The displacements of particles near\nthe swimmer diverge in a manner similar to an isolated no-slip sphere, but with\na smaller coefficient due to the action of the flagellum. Far from the swimmer,\nthe time dependence becomes negligible due to both being very fast and decaying\nwith distance. Finally, we compute the probability distribution of particle\ndisplacements, and find that our model has fatter tails than previous steady\nmodels, due to the presence of a no-slip surface that drags particles along.",
        "positive": "Tuning of friction noise by accessing the rolling-sliding option: Variable power transmission in mechanical systems is often achieved by\ndevices, e.g., clutches and brakes, that use dry friction. In these systems,\nthe variability in power transmission is brought about by engaging and\ndisengaging the friction plates. Though commonly used, this method of making\nthe coupling noisy is not as versatile as their electrical analog. An\nalternative method would be to intermittently vary the frictional force. In\nthis paper, we demonstrate a self-organized way to tune the noise in the\nfrictional coupling between two surfaces which are in relative motion with each\nother. This is achieved by exploiting the complexity that arises from the\nfrictional interaction of the balls which are placed in a circular groove\nbetween the surfaces. The extent of floppiness in the coupling is related to\nthe rate at which the balls make transitions between their rolling and sliding\nstates. If the moving surface is soft and the static surface is hard we show\nthat with increasing filling fraction of the balls the transitions between\nrolling and sliding against the static surface give way to the transitions\nbetween rolling and sliding against the moving surface. As a consequence, the\nnoise in the coupling is large for both small and large filling fraction with a\ndip in the middle. In contrast, the sliding with the static surface is\nsuppressed if the moving pate is hard and the noise in the coupling decreases\nmonotonically with the filling fraction of the balls."
    },
    {
        "anchor": "Dynamic Monte Carlo algorithm for out-of-equilibrium processes in\n  colloidal dispersions: Colloids have a striking relevance in a wide spectrum of industrial\nformulations, spanning from personal care products to protective paints. Their\nbehaviour can be easily influenced by extremely weak forces, which disturb\ntheir thermodynamic equilibrium and dramatically determine their performance.\nMotivated by the impact of colloidal dispersions in fundamental science and\nformulation engineering, we have designed an efficient Dynamic Monte Carlo\n(DMC) approach to mimic their out-of-equilibrium dynamics. Our recent theory,\nwhich provided a rigorous method to reproduce the Brownian motion of colloids\nby MC simulations, is here generalised to reproduce the Brownian motion of\ncolloidal particles during transitory unsteady states, when their thermodynamic\nequilibrium is significantly modified. To this end, we investigate monodisperse\nand bidisperse rod-like particles in the isotropic phase and apply an external\nfield that forces their reorientation along a common direction and induces an\nisotropic-to-nematic phase transition. We also study the behaviour of the\nsystem once the external field is removed. Our simulations are in excellent\nquantitative agreement with Brownian Dynamics simulations when the DMC results\nare rescaled with a time-dependent acceptance ratio, which depends on the\nstrength of the applied field. Further generalising our DMC algorithm to\nprocesses displaying significant density fluctuations, such as nucleation and\ngrowth, where the MC acceptance ratio is expected to depend on both time and\nspace, is currently under investigation.",
        "positive": "DNA-Programmed Mesoscopic Architecture: We study the problem of the self-assembly of nanoparticles (NPs) into finite\nmesoscopic structures with a programmed local morphology and complex overall\nshape. Our proposed building blocks are NPs directionally-functionalized with\nDNA. The combination of directionality and selectivity of interactions allows\none to avoid unwanted metastable configurations which have been shown to lead\nto slow self-assembly kinetics even in much simpler systems. With numerical\nsimulations, we show that a variety of target mesoscopic objects can be\ndesigned and self-assembled in near perfect yield. They include cubes,\npyramids, boxes and even an Empire State Building model. We summarize our\nfindings with a set of design strategies that lead to the successful\nself-assembly of a wide range of mesostructures."
    },
    {
        "anchor": "High-gravity Spreading of Liquid Coatings on Wetting Flexible Substrates: This work describes a mechanical approach for manipulating the capillary\nlength and spreading of liquid coatings on flexible substrates with high\ngravity. Experimental verification in the literature has focused on cases under\nstandard gravity on earth, and to the authors' knowledge, this work is the\nfirst to explore its relevance to spreading puddles under high gravity. By\nusing centrifugation with a high-density liquid base underneath a coated\nsubstrate, it is possible to apply acceleration normal to a substrate to\ndecrease the capillary length and increase the rate of spreading. Due to the\nnature of centrifugation, this method works primarily on flexible substrates,\nwhich bend with a curvature that conforms to a contour of uniformly distributed\ncentrifugal acceleration. With high gravity of 600 g applied, the capillary\nlength reduces by a factor of 24.5, and the spreading shifts from \"transient\nspreading\" between the surface tension-driven and gravity-driven regimes to the\ngravity-driven regime. Experimental results show that high gravitational\nacceleration will enhance the rate of spreading such that a puddle, which would\nrequire 12 hours under standard gravity on earth to go from an 8-{\\mu}l droplet\nto a 40-{\\mu}m thick puddle, would require less than 1 minute under 600 g.\nOverall, this work suggests that previously derived expressions for\ngravity-driven spreading of puddles under earth's standard gravity extend to\npredicting the behavior of puddles spreading on smooth, wetting substrates\nexposed to more than 100 g's of acceleration.",
        "positive": "Axisymmetric column collapses of bi-frictional granular mixtures: The behavior of granular column collapses is associated with the dynamics of\ngeohazards, such as debris flows, landslides, and pyroclastic flows, yet its\nunderlying physics is still not well understood. In this paper, we explore\ngranular column collapses using the spheropolyhedral discrete element method\n(DEM), where the system contains two types of particles with different\nfrictional properties. We impose three different mixing ratios and multiple\ndifferent particle frictional coefficients, which lead to different run-out\ndistances and deposition heights. Based on our previous work and a simple\nmixture theory, we propose a new effective initial aspect ratio for the\nbi-frictional granular mixture, which helps unify the description of the\nrelative run-out distances. We analyze the kinematics of bi-frictional granular\ncolumn collapses and find that deviations from classical power-law scaling in\nboth the dimensionless terminal time and the dimensionless time when the system\nreaches the maximum kinetic energy may result from differences in the initial\nsolid fraction and initial structures. To clarify the influence of initial\nstates, we further decrease the initial solid fraction of granular column\ncollapses, and propose a trial function to quantitatively describe its\ninfluence. Due to the utilization of a simple mixture theory of contact\noccurrence probability, this study can be associated with the\nfriction-dependent rheology of granular systems and friction-induced granular\nsegregations, and further generalized into applications with multiple species\nof particles in various natural and engineering mixtures."
    },
    {
        "anchor": "Measuring the characteristics of electroosmotic flow in a\n  polyelectrolyte grafted nanopore by molecular theory approach: In this paper, we present a molecular theory analysis of ions and potential\ndistribution, degree of ionization of polyelectrolyte (PE) brushes, velocity\nprofile, volumetric flow rate, ionic selectivity, ionic conduction and\nadvection by electroosmotic flow in poly-acid (PA)/poly-base (PB) grafted\nnanopores. The generated conformations by the Rotational Isomeric State model\nare used in performing the minimization of the free energy functional of the\nsystem including the effects of the Born energy arising from the variation of\npermittivity, pH of the electrolyte, grafting density of weak PE brushes, ion\npartitioning and ionic size. Then, the velocity field is obtained in the\nprocess of solving the Navier-Stokes-Brinkman equation by considering the\ninterfacial fluid/wall slippage. Also, the accuracy of the numerical solutions\nis examined by comparing the present results of ionic conductivity with the\nexisting experimental data for a nanopore grafted with 4PVP brushes used as a\nsynthetic proton-gated ion channel. The application of the present methodology\nenables us to describe the electrohydrodynamic characteristics of\nelectroosmotic flow in PE grafted nanopores in terms of different factors\nincluding the pH of the electrolyte, bulk salt concentration and the grafting\ndensity of PE brushes. We show that the dependency of the quantities of\ninterest are essentially rely on the type of the polymer chains. For instance,\nincreasing the pH of the electrolyte results in an increase/decrease of the\ndegree of charged sites in the PA/PB brushes, and there exists a\nminimum/maximum point in the variation of magnitude of the ion selectivity of\nPA/PB grafted nanopore with the pH of the electrolyte. However, for both types\nof PA and PB grafted nanopores, ionic conduction and advection are\napproximately the ascending function of the bulk salt concentration and low\nrange grafting density of the PE layer.",
        "positive": "Discontinuous Thinning in Active Microrheology of Soft Complex Matter: Employing theory and numerical simulations, we demonstrate discontinuous\nforce thinning due to the motion of an external probe in a host medium, which\nwe approximate as structureless. When the driving of the probe exceeds a\ncritical force, the microviscosity of the medium drops abruptly by about an\norder of magnitude. This phenomenon occurs for strong attractive interactions\nbetween probe and a sufficiently dense host medium."
    },
    {
        "anchor": "Fluid mixing by curved trajectories of microswimmers: We consider the tracer diffusion $D_{rr}$ that arises from the run-and-tumble\nmotion of low Reynolds number swimmers, such as bacteria. Assuming a dilute\nsuspension, where the bacteria move in uncorrelated runs of length $\\lambda$,\nwe obtain an exact expression for $D_{rr}$ for dipolar swimmers in three\ndimensions, hence explaining the surprising result that this is independent of\n$\\lambda$. We compare $D_{rr}$ to the contribution to tracer diffusion from\nentrainment.",
        "positive": "A Free Energy Landscape for Cage Breaking of Three Hard Disks: We investigate cage breaking in dense hard disk systems using a model of\nthree Brownian disks confined within a circular corral. This system has a\nsix-dimensional configuration space, but can be equivalently thought to explore\na symmetric one-dimensional free energy landscape containing two energy minima\nseparated by an energy barrier. The exact free energy landscape can be\ncalculated as a function of system size. Results of simulations show the\naverage time between cage breaking events follows an Arrhenius scaling when the\nenergy barrier is large. We also discuss some of the consequences of using a\none-dimensional representation to understand dynamics in a multi-dimensional\nspace, such as diffusion acquiring spatial dependence and discontinuities in\nspatial derivatives of free energy."
    },
    {
        "anchor": "Density of states of colloidal glasses: Glasses are structurally liquid-like, but mechanically solid-like. Most\nattempts to understand glasses start from liquid state theory. Here we take the\nopposite point of view, and use concepts from solid state physics. We determine\nthe vibrational modes of a colloidal glass experimentally, and find soft\nlow-frequency modes that are very different in nature from the usual acoustic\nvibrations of ordinary solids. These modes extend over surprisingly large\nlength scales.",
        "positive": "Physical and Computational Scaling Issues in Lattice Boltzmann\n  Simulations of Binary Fluid Mixtures: We describe some scaling issues that arise when using lattice Boltzmann\nmethods to simulate binary fluid mixtures -- both in the presence and in the\nabsence of colloidal particles. Two types of scaling problem arise: physical\nand computational. Physical scaling concerns how to relate simulation\nparameters to those of the real world. To do this effectively requires careful\nphysics, because (in common with other methods) lattice Boltzmann cannot fully\nresolve the hierarchy of length, energy and time scales that arise in typical\nflows of complex fluids. Care is needed in deciding what physics to resolve and\nwhat to leave unresolved, particularly when colloidal particles are present in\none or both of two fluid phases. This influences steering of simulation\nparameters such as fluid viscosity and interfacial tension. When the physics is\nanisotropic (for example, in systems under shear) careful adaptation of the\ngeometry of the simulation box may be needed; an example of this, relating to\nour study of the effect of colloidal particles on the Rayleigh-Plateau\ninstability of a fluid cylinder, is described. The second and closely related\nset of scaling issues are computational in nature: how do you scale up\nsimulations to very large lattice sizes? The problem is acute for systems\nundergoing shear flow. Here one requires a set of blockwise co-moving frames to\nthe fluid, each connected to the next by a Lees-Edwards like boundary\ncondition. These matching planes lead to small numerical errors whose\ncumulative effects can become severe; strategies for minimising such effects\nare discussed."
    },
    {
        "anchor": "Design principles for fast and efficient self-assembly processes: Self-assembly is a fundamental concept in biology and of significant interest\nto nanotechnology. Significant progress has been made in characterizing and\ncontrolling the properties of the resulting structures, both experimentally and\ntheoretically. However, much less is known about kinetic constraints and\ndeterminants of dynamical properties like time efficiency, although these\nconstraints can become severe limiting factors of self-assembly processes. Here\nwe investigate how the time efficiency and other dynamical properties of\nreversible self-assembly depend on the morphology (shape) of the building\nblocks for systems in which the binding energy between the constituents is\nlarge. As paradigmatic examples, we stochastically simulate the self-assembly\nof constituents with triangular, square, and hexagonal morphology into\ntwo-dimensional structures of a specified size. We find that the constituents'\nmorphology critically determines the assembly time and how it scales with the\nsize of the target structure. Our analysis reveals three key structural\nparameters defined by the morphology: The nucleation size and attachment order,\nwhich describe the effective order of the chemical reactions by which clusters\nnucleate and grow, respectively, and the growth exponent, which determines how\nthe growth rate of an emerging structure scales with its size. Using this\ncharacterization, we formulate an effective theory of the self-assembly\nkinetics, which we show exhibits an inherent scale invariance. This allows us\nto identify general scaling laws that describe the minimal assembly time as a\nfunction of the size of the target structure. We show how these insights on the\nkinetics of self-assembly processes can be used to design assembly schemes that\ncould significantly increase the time efficiency and robustness of artificial\nself-assembly processes.",
        "positive": "Instability and Periodic Deformation in Bilayer Membranes Induced by\n  Freezing: The instability and periodic deformation of bilayer membranes during freezing\nprocesses are studied as a function of the difference of the shape energy\nbetween the high and the low temperature membrane states. It is shown that\nthere exists a threshold stability condition, bellow which a planar\nconfiguration will be deformed. Among the deformed shapes, the periodic curved\nsquare textures are shown being one kind of the solutions of the associated\nshape equation. In consistency with recent expe rimental observations, the\noptimal ratio of period and amplitude for such a texture is found to be\napproximately equal to (2)^{1/2}\\pi."
    },
    {
        "anchor": "Cross-stream migration of active particles: For natural microswimmers, the interplay of swimming activity and external\nflow can promote robust motion, e.g. propulsion against (\"upstream rheotaxis\")\nor perpendicular to the direction of flow. These effects are generally\nattributed to their complex body shapes and flagellar beat patterns. Here,\nusing catalytic Janus particles as a model experimental system, we report on a\nstrong directional response that occurs for spherical active particles in a\nchannel flow. The particles align their propulsion axes to be nearly\nperpendicular to both the direction of flow and the normal vector of a nearby\nbounding surface. We develop a deterministic theoretical model of spherical\nmicroswimmers near a planar wall that captures the experimental observations.\nWe show how the directional response emerges from the interplay of shear flow\nand near-surface swimming activity. Finally, adding the effect of thermal\nnoise, we obtain probability distributions for the swimmer orientation that\nsemi-quantitatively agree with the experimental distributions.",
        "positive": "Granular size segregation in underwater sand ripples: We report an experimental study of a binary sand bed under an oscillating\nwater flow. The formation and evolution of ripples is observed. The appearance\nof a granular segregation is shown to strongly depend on the sand bed\npreparation. The initial wavelength of the mixture is measured. In the final\nsteady state, a segregation in volume is observed instead of a segregation at\nthe surface as reported before. The correlation between this phenomenon and the\nfluid flow is emphasised. Finally, different ``exotic'' patterns and their\ngeophysical implications are presented."
    },
    {
        "anchor": "Analytical soft-core potentials for macromolecular fluids and mixtures: An analytical description of polymer melts and their mixtures as liquids of\ninteracting soft colloidal particles is obtained from liquid-state theory. The\nderived center-of-mass pair correlation functions with no adjustable parameters\nreproduce those computed from united atom molecular dynamics simulations. The\ncoarse-grained description correctly bridges micro- and mesoscopic fluid\nproperties. Molecular dynamics simulations of soft colloidal particles\ninteracting through the calculated effective pair potentials are consistent\nwith data from microscale simulations and analytical formulas.",
        "positive": "Molecular Fluid Flow in MoS$_2$ Nanoporous Membranes and Hydrodynamics\n  Interactions: The shift in water security demands improvements in alternative solutions\nsuch as saltwater desalination. One of the most efficient technologies in this\nscope is the reverse osmosis systems, a technology based on a membrane\nseparation process. MoS$_2$ nanoporous membranes are gained attention as a\npromise for the next-generation high selective and permeable membranes\ntechnology. Besides that, one aspect of nanoconfined fluid flow not yet\ninvestigated but studied from the fluid mechanics calculations is the impact of\ninduced pressure fields in the water flux in neighboring microfilters,\ndescribed as hydrodynamic interactions. For this purpose, we studied the water\nflow through adjacent MoS$_2$ nanopores by running Non-Equilibrium Molecular\nDynamics simulations and obtained that in this scale the hydrodynamics\ninteractions are not significant as expected."
    },
    {
        "anchor": "Actively crosslinked microtubule networks: mechanics, dynamics and\n  filament sliding: Cytoskeletal networks are foundational examples of active matter and central\nto self-organized structures in the cell. In vivo, these networks are active\nand heavily crosslinked. Relating their large-scale dynamics to properties of\ntheir constituents remains an unsolved problem. Here we study an in vitro\nsystem made from microtubules and XCTK2 kinesin motors, which forms an aligned\nand active gel. Using photobleaching we demonstrate that the gel's aligned\nmicrotubules, driven by motors, continually slide past each other at a speed\nindependent of the local polarity. This phenomenon is also observed, and\nremains unexplained, in spindles. We derive a general framework for coarse\ngraining microtubule gels crosslinked by molecular motors from microscopic\nconsiderations. Using the microtubule-microtubule coupling, and force-velocity\nrelationship for kinesin, this theory naturally explains the experimental\nresults: motors generate an active strain-rate in regions of changing polarity,\nwhich allows microtubules of opposite polarities to slide past each other\nwithout stressing the material.",
        "positive": "Critical exponents of the two-layer Ising model: The symmetric two-layer Ising model (TLIM) is studied by the corner transfer\nmatrix renormalisation group method. The critical points and critical exponents\nare calculated. It is found that the TLIM belongs to the same universality\nclass as the Ising model. The shift exponent is calculated to be 1.773, which\nis consistent with the theoretical prediction 1.75 with 1.3% deviation."
    },
    {
        "anchor": "Finite-difference methods for simulation models incorporating\n  non-conservative forces: We discuss algorithms applicable to the numerical solution of second-order\nordinary differential equations by finite-differences. We make particular\nreference to the solution of the dissipative particle dynamics fluid model, and\npresent extensive results comparing one of the algorithms discussed with the\nstandard method of solution. These results show the successful modeling of\nphase separation and surface tension in a binary immiscible fluid mixture.",
        "positive": "Capillary force-induced structural instability in liquid infiltrated\n  elastic circular tubes: The capillary-induced structural instability of an elastic circular tube\npartially filled by a liquid is studied by combining theoretical analysis and\nmolecular dynamics simulations. The analysis shows that, associated with the\ninstability, there is a well-defined length scale (elasto-capillary length),\nwhich exhibits a scaling relationship with the characteristic length of the\ntube, regardless of the interaction details. We validate this scaling\nrelationship for a carbon nanotube partially filled by liquid iron. The\ncapillary-induced structural transformation could have potential applications\nfor nano-devices."
    },
    {
        "anchor": "Physics of Electrostatic Projection Revealed by High-Speed Video Imaging: Processes based on electrostatic projection are used extensively in industry,\ne.g. for mineral separations, electrophotography or manufacturing of coated\nabrasives, such as sandpaper. Despite decades of engineering practice, there\nare still unanswered questions. In this paper, we present a comprehensive\nexperimental study of projection process of more than 1500 individual spherical\nalumina particles with a nominal size of 500 $\\mu$m, captured by high-speed\nvideo imaging and digital image analysis. Based on flight trajectories of\napproximately 1100 projected particles, we determined the acquired charge and\ndynamics as a function of relative humidity (RH) and electric field intensity\nand compared the results with classical theories. For RH levels of 50\\% and\nabove, more than 85\\% of disposed particles were projected, even when the\nelectric field intensity was at its minimum level. This suggests that, beyond a\ncritical value of electric field intensity, relative humidity plays a more\ncritical role in the projection process. We also observed that the charging\ntime is reduced dramatically for RH levels of 50\\% and above, possibly due to\nthe build-up of thin water films around the particles which can facilitate\ncharge transfer. In contrast, projected particles at 30\\% RH level exhibited an\nexcessive amount of electric charge, between two to four times than that of\nsaturation value, which might be attributed to triboelectric charging effects.\nFinally, the physics of electrostatic projection is compared and contrasted\nwith those of induced-charge electrokinetic phenomena, which share similar\nfield-square scaling, as the applied field acts on its own induced charge to\ncause particle motion.",
        "positive": "Fundamental measure theory for lattice fluids with hard core\n  interactions: We present the extension of Rosenfeld's fundamental measure theory to lattice\nmodels by constructing a density functional for d-dimensional mixtures of\nparallel hard hypercubes on a simple hypercubic lattice. The one-dimensional\ncase is exactly solvable and two cases must be distinguished: all the species\nwith the same lebgth parity (additive mixture), and arbitrary length parity\n(nonadditive mixture). At the best of our knowledge, this is the first time\nthat the latter case is considered. Based on the one-dimensional exact\nfunctional form, we propose the extension to higher dimensions by generalizing\nthe zero-dimensional cavities method to lattice models. This assures the\nfunctional to have correct dimensional crossovers to any lower dimension,\nincluding the exact zero-dimensional limit. Some applications of the functional\nto particular systems are also shown."
    },
    {
        "anchor": "The liquid-vapor interface of the restricted primitive model of ionic\n  fluids from a density functional approach: We investigate the liquid-vapor interface of the restricted primitive model\nfor an ionic fluid using a density functional approach. The applied theory\nincludes the electrostatic contribution to the free energy functional arising\nfrom the bulk energy equation of state and the mean spherical approximation for\na restricted primitive model, as well as the associative contribution, due to\nthe formation of pairs of ions. We compare the density profiles and the values\nof the surface tension with previous theoretical approaches.",
        "positive": "Dynamic clustering and chemotactic collapse of self-phoretic active\n  particles: Recent experiments with self-phoretic particles at low concentrations show a\npronounced dynamic clustering [I. Theurkauff \\emph{et al.}, Phys.\\ Rev.\\ Lett.\\\n\\textbf{108}, 268303 (2012)]. We model this situation by taking into account\nthe translational and rotational diffusiophoretic motion, which the active\nparticles perform in their self-generated chemical field. Our Brownian dynamics\nsimulations show pronounced dynamic clustering only when these two phoretic\ncontributions give rise to competing attractive and repulsive interactions,\nrespectively. We identify two dynamic clustering states and characterize them\nby power-law-exponential distributions. In case of mere attraction a\nchemotactic collaps occurs directly from the gas-like into the collapsed state,\nwhich we also predict by mapping our Langevin dynamics on the Keller-Segel\nmodel for bacterial chemotaxis."
    },
    {
        "anchor": "Period fissioning and other instabilities of stressed elastic membranes: We study the shapes of elastic membranes under the simultaneous exertion of\ntensile and compressive forces when the translational symmetry along the\ntension direction is broken. We predict a multitude of novel morphological\nphases in various regimes of a 2-dimensional parameter space $(\\epsilon,\\nu)$\nthat defines the relevant mechanical and geometrical conditions. Theses\nparameters are, respectively, the ratio between compression and tension, and\nthe wavelength contrast along the tension direction. In particular, our theory\nassociates the repetitive increase of pattern periodicity, recently observed on\nwrinkled membranes floating on liquid and subject to capillary forces, to the\nmorphology in the regime ($\\epsilon \\ll 1,\\nu \\gg 1$) where tension is dominant\nand the wavelength contrast is large.",
        "positive": "Effect of inelasticity on the phase transitions of a thin vibrated\n  granular layer: We describe an experimental and computational investigation of the ordered\nand disordered phases of a vibrating thin, dense granular layer composed of\nidentical metal spheres. We compare the results from spheres with different\namounts of inelasticity and show that inelasticity has a strong effect on the\nphase diagram. We also report the melting of an ordered phase to a homogeneous\ndisordered liquid phase at high vibration amplitude or at large inelasticities.\nOur results show that dissipation has a strong effect on ordering and that in\nthis system ordered phases are absent entirely in highly inelastic materials."
    },
    {
        "anchor": "Non-Equilibrium Dynamics of Single polymer Adsorption to Solid Surfaces: Adsorption of polymers to surfaces is crucial for understanding many\nfundamental processes in nature. Recent experimental studies indicate that the\nadsorption dynamics is dominated by non-equilibrium effects. We investigate the\nadsorption of a single polymer of length $N$ to a planar solid surface in the\nabsence of hydrodynamic interactions. We find that for weak adsorption energies\nthe adsorption time scales $ \\sim N^{(1+2\\nu)/(1+\\nu)}$, where $\\nu$ is the\nFlory exponent for the polymer. We argue that in this regime the single chain\nadsorption is closely related to a field-driven polymer translocation through\nnarrow pores. Surprisingly, for high adsorption energies the adsorption time\nbecomes longer, as it scales $\\sim N^{(1+\\nu)}$, which is explained by strong\nstretching of the unadsorbed part of the polymer close to the adsorbing\nsurface. These two dynamic regimes are separated by an energy scale that is\ncharacterised by non-equilibrium contributions during the adsorption process.",
        "positive": "Chiral active hexatics: Giant number fluctuations, waves and destruction\n  of order: Active materials, composed of internally driven particles, have properties\nthat are qualitatively distinct from matter at thermal equilibrium. However,\nthe most spectacular departures from equilibrium phase behaviour are thought to\nbe confined to systems with polar or nematic asymmetry. In this paper, we show\nthat such departures are also displayed in more symmetric phases such as\nhexatics if, in addition, the constituent particles have chiral asymmetry. We\nshow that chiral active hexatics whose rotation rate does not depend on density\nhave giant number fluctuations. If the rotation rate depends on density, the\ngiant number fluctuations are suppressed due to a novel orientation-density\nsound mode with a linear dispersion which propagates even in the overdamped\nlimit. However, we demonstrate that beyond a finite but large lengthscale, a\nchirality and activity-induced relevant nonlinearity invalidates the\npredictions of the linear theory and destroys the hexatic order. In addition,\nwe show that activity modifies the interactions between defects in the active\nchiral hexatic phase, making them non-mutual. Finally, to demonstrate the\ngenerality of a chiral active hexatic phase we show that it results from the\nmelting of chiral active crystals in finite systems."
    },
    {
        "anchor": "What is the stiffness of a bent book?: We study the bending of a book-like system, comprising a stack of elastic\nplates coupled through friction. The behavior of this layered system is rich\nand nontrivial, with a non-additive enhancement of the apparent stiffness and a\nsignificant hysteretic response. A dimension reduction procedure is employed to\ndevelop a centerline-based theory describing the stack as a non-linear planar\nrod with internal shear. We consider the coupling between the nonlinear\ngeometry and the elasticity of the stacked plates, treating the interlayer\nfriction perturbatively. This model yields predictions for the stack's\nmechanical response in three-point bending that are in excellent agreement with\nour experiments. Remarkably, we find that the energy dissipated during\ndeformation can be rationalized over three orders of magnitude, including the\nregimes of a thick stack with large deflection. This robust dissipative\nmechanism could be harnessed to design new classes of low-cost and efficient\ndamping devices.",
        "positive": "Three-dimensional patchy lattice model: ring formation and phase\n  separation: We investigate the structural and thermodynamic properties of a model of\nparticles with $2$ patches of type $A$ and $10$ patches of type $B$. Particles\nare placed on the sites of a face centered cubic lattice with the patches\noriented along the nearest neighbor directions. The competition between the\nself-assembly of chains, rings and networks on the phase diagram is\ninvestigated by carrying out a systematic investigation of this class of\nmodels, using an extension of Wertheim's theory for associating fluids and\nMonte Carlo numerical simulations. We varied the ratio\n$r\\equiv\\epsilon_{AB}/\\epsilon_{AA}$ of the interaction between patches $A$ and\n$B$, $\\epsilon_{AB}$, and between $A$ patches, $\\epsilon_{AA}$ ($\\epsilon_{BB}$\nis set to $0$) as well as the relative position of the $A$ patches, i.e., the\nangle $\\theta$ between the (lattice) directions of the $A$ patches. We found\nthat both $r$ and $\\theta$ ($60^\\circ,90^\\circ,$ or $120^\\circ$) have a\nprofound effect on the phase diagram. In the empty fluid regime ($r < 1/2$) the\nphase diagram is re-entrant with a closed miscibility loop. The region around\nthe lower critical point exhibits unusual structural and thermodynamic behavior\ndetermined by the presence of relatively short rings. The agreement between the\nresults of theory and simulation is excellent for $\\theta=120^\\circ$ but\ndeteriorates as $\\theta$ decreases, revealing the need for new theoretical\napproaches to describe the structure and thermodynamics of systems dominated by\nsmall rings."
    },
    {
        "anchor": "Emergence and evolution of $k$-gap in spectra of liquid and\n  supercritical states: Fundamental understanding of strongly-interacting systems necessarily\ninvolves collective modes, but their nature and evolution is not generally\nunderstood in dynamically disordered and strongly-interacting systems such as\nliquids and supercritical fluids. We report the results of extensive molecular\ndynamics simulations and provide direct evidence that liquids develop a gap in\nsolid-like transverse spectrum in the reciprocal space, with no propagating\nmodes between zero and a threshold value. In addition to the liquid state, this\nresult importantly applies to the supercritical state of matter. We show that\nthe emerging gap increases with the inverse of liquid relaxation time and\ndiscuss how the gap affects properties of liquid and supercritical states.",
        "positive": "Theoretical Framework for Microscopic Osmotic Phenomena: The basic ingredients of osmotic pressure are a solvent fluid with a soluble\nmolecular species which is restricted to a chamber by a boundary which is\npermeable to the solvent fluid but impermeable to the solute molecules. For\nmacroscopic systems at equilibrium, the osmotic pressure is given by the\nclassical van't Hoff Law, which states that the pressure is proportional to the\nproduct of the temperature and the difference of the solute concentrations\ninside and outside the chamber. For microscopic systems the diameter of the\nchamber may be comparable to the length-scale associated with the solute-wall\ninteractions or solute molecular interactions. In each of these cases, the\nassumptions underlying the classical van't Hoff Law may no longer hold. In this\npaper we develop a general theoretical framework which captures corrections to\nthe classical theory for the osmotic pressure under more general relationships\nbetween the size of the chamber and the interaction length scales. We also show\nthat notions of osmotic pressure based on the hydrostatic pressure of the fluid\nand the mechanical pressure on the bounding walls of the chamber must be\ndistinguished for microscopic systems. To demonstrate how the theoretical\nframework can be applied, numerical results are presented for the osmotic\npressure associated with a polymer of N monomers confined in a spherical\nchamber as the bond strength is varied."
    },
    {
        "anchor": "Kramers escape of a self-propelled particle: We investigate the escape rate of an overdamped, self-propelled spherical\nBrownian particle on a surface from a metastable potential well. Within a\nmodeling in terms of a 1D constant speed of the particle's active dynamics we\nconsider the associated rate using both numerical and analytical approaches.\nRegarding the properties of the stationary state in the potential well, two\nmajor timescales exist, each governing the translational and the rotational\ndynamics of the particle, respectively. The particle radius is identified to\npresent the essential quantity in charge of regulating the ratio between those\ntimescales. For very small and very large particle radii, approximate analytic\nexpressions for the particle's escape rate can be derived, which, within their\nrespective range of validity, compare favorably with the precise escape\nnumerics of the underlying full two-dimensional Fokker-Planck description.",
        "positive": "Under pressure: Hydrogel swelling in a granular medium: Hydrogels hold promise in agriculture as reservoirs of water in dry soil,\npotentially alleviating the burden of irrigation. However, confinement in soil\ncan markedly reduce the ability of hydrogels to absorb water and swell,\nlimiting their widespread adoption. Unfortunately, the underlying reason\nremains unknown. By directly visualizing the swelling of hydrogels confined in\nthree-dimensional granular media, we demonstrate that the extent of hydrogel\nswelling is determined by the competition between the force exerted by the\nhydrogel due to osmotic swelling and the confining force transmitted by the\nsurrounding grains. Furthermore, the medium can itself be restructured by\nhydrogel swelling, as set by the balance between the osmotic swelling force,\nthe confining force, and intergrain friction. Together, our results provide\nquantitative principles to predict how hydrogels behave in confinement,\npotentially improving their use in agriculture as well as informing other\napplications such as oil recovery, construction, mechanobiology, and\nfiltration."
    },
    {
        "anchor": "Dynamic characterization of cellulose nanofibrils in sheared and\n  extended semi-dilute dispersions: New materials made through controlled assembly of dispersed cellulose\nnanofibrils (CNF) has the potential to develop into biobased competitors to\nsome of the highest performing materials today. The performance of these new\ncellulose materials depends on how easily CNF alignment can be controlled with\nhydrodynamic forces, which are always in competition with a different process\ndriving the system towards isotropy, called rotary diffusion. In this work, we\npresent a flow-stop experiment using polarized optical microscopy (POM) to\nstudy the rotary diffusion of CNF dispersions in process relevant flows and\nconcentrations. This is combined with small angle X-ray scattering (SAXS)\nexperiments to analyze the true orientation distribution function (ODF) of the\nflowing fibrils. It is found that the rotary diffusion process of CNF occurs at\nmultiple time scales, where the fastest scale seems to be dependent on the\ndeformation history of the dispersion before the stop. At the same time, the\nhypothesis that rotary diffusion is dependent on the initial ODF does not hold\nas the same distribution can result in different diffusion time scales. The\nrotary diffusion is found to be faster in flows dominated by shear compared to\npure extensional flows. Furthermore, the experimental setup can be used to\nquickly characterize the dynamic properties of flowing CNF and thus aid in\ndetermining the quality of the dispersion and its usability in material\nprocesses.",
        "positive": "Mechanism of membrane tube formation induced by adhesive nanocomponents: We report numerical simulations of membrane tubulation driven by large\ncolloidal particles. Using Monte Carlo simulations we study how the process\ndepends on particle size, concentration and binding strength, and present\naccurate free energy calculations to sort out how tube formation compares with\nthe competing budding process. We find that tube formation is a result of the\ncollective behavior of the particles adhering on the surface, and it occurs for\nbinding strengths that are smaller than those required for budding. We also\nfind that long linear aggregates of particles forming on the membrane surface\nact as nucleation seeds for tubulation by lowering the free energy barrier\nassociated to the process."
    },
    {
        "anchor": "Quantification of the Heterogeneity of Particle Packings: The microstructure of coagulated colloidal particles, for which the\ninter-particle potential is described by the DLVO theory, is strongly\ninfluenced by the particles' surface potential. Depending on its value, the\nresulting microstructures are either more \"homogeneous\" or more\n\"heterogeneous\", at equal volume fractions. An adequate quantification of a\nstructure's degree of heterogeneity (DOH) however does not yet exist. In this\nwork, methods to quantify and thus classify the DOH of microstructures are\ninvestigated and compared. Three methods are evaluated using particle packings\ngenerated by Brownian dynamics simulations: (1) the pore size distribution, (2)\nthe density fluctuation method and (3) the Voronoi volume distribution. Each\nmethod provides a scalar measure, either via a parameter in a fit function or\nan integral, which correlates with the heterogeneity of the microstructure and\nwhich thus allows for the first time to quantitatively capture the DOH of a\ngranular material. An analysis of the differences in the density fluctuations\nbetween two structures additionally allows for a detailed determination of the\nlength scale on which differences in heterogeneity are most pronounced.",
        "positive": "Driven translocation of a flexible polymer through an interacting\n  conical pore: We study the driven translocation of a flexible polymer through an\ninteracting conical pore using Langevin dynamics simulations. We find that, for\na fixed value of externally applied force and pore polymer interaction\nstrength, the mean residence time of monomers inside the pore shows\nnon-monotonic variations with pore apex angle $\\alpha$. We explain this\nbehavior using a free energy argument by explicitly accounting for pore-polymer\ninteractions and external drive. Our theoretical observations are corroborated\nby the simulation results of the mean translocation times as the pore-polymer\ninteractions and external driving force are varied."
    },
    {
        "anchor": "A simple micro-swimmer model inspired by the general equation for\n  nonequilibrium reversible-irreversible coupling: A simple mean-field micro-swimmer model is presented. The model is inspired\nby the nonequilibrium thermodynamics of multi-component fluids that undergo\nchemical reactions. These thermodynamics can be rigorously described in the\ncontext of the GENERIC (general equation for the nonequilibrium\nreversible-irreversible coupling) framework. More specifically this approach\nwas recently applied to non-ideal polymer solutions (Indei and Schieber, J.\nChem. Phys, 146, 184902, 2017). One of the species of the solution is an\nunreactive polymer chain represented by the bead-spring model. Using this\ndetailed description as inspiration we then make several simplifying\nassumptions to obtain a mean-field model for a Janus micro-swimmer. The swimmer\nmodel considered here consists of a polymer dumbbell in a sea of reactants. One\nof the beads of the dumbbell is allowed to act as a catalyst for a chemical\nreaction between the reactants. We show that the mean-squared displacement,\nMSD, of the center of mass of this Janus dumbbell exhibits ballistic behavior\nat time scales at which the concentration of reactant is large. The time scales\nat which the ballistic behavior is observed in the MSD coincides with the time\nscales at which the cross-correlation between the swimmer's orientation and the\ndirection of its displacement exhibit a maximum. Since the swimmer model was\ninspired by the GENERIC framework it is possible to ensure that the entropy\ngeneration is always positive and therefore the second law of thermodynamics is\nobeyed.",
        "positive": "Wetting and phase separation in soft adhesion: In the classic theory of solid adhesion, surface energy drives deformation to\nincrease contact area while bulk elasticity opposes it. Recently, solid surface\nstress has been shown also to play an important role in opposing deformation of\nsoft materials. This suggests that the contact line in soft adhesion should\nmimic that of a liquid droplet, with a contact angle determined by surface\ntensions. Consistent with this hypothesis, we observe a contact angle of a soft\nsilicone substrate on rigid silica spheres that depends on the surface\nfunctionalization but not the sphere size. However, to satisfy this wetting\ncondition without a divergent elastic stress, the gel separates from its\nsolvent near the contact line. This creates a four-phase contact zone with two\nadditional contact lines hidden below the surface of the substrate. While the\ngeometries of these contact lines are independent of the size of the sphere,\nthe volume of the phase-separated region is not, but rather depends on the\nindentation volume. These results indicate that theories of adhesion of soft\ngels need to account for both the compressibility of the gel network and a\nnon-zero surface stress between the gel and its solvent."
    },
    {
        "anchor": "Polymorphism of the glass former ethanol confined in mesoporous silicon: X-ray diffraction patterns of ethanol confined in parallel-aligned channels\nof approx. 10 nm diameter and 50 micrometer length in mesoporous silicon have\nbeen recorded as a function of filling fraction, temperature and for varying\ncooling and heating rates. A sorption isotherm, recorded in the liquid state,\nindicates a three monolayer thick, strongly adsorbed wall layer and a capillary\ncondensed fraction of molecules in the pore center. Though the strongly\nadsorbed film remains in an amorphous state for the entire temperature range\ninvestigated, the capillary condensed molecules reproduce the polymorphism of\nbulk solid ethanol, that is the formation of either crystalline or glass-like\nstates as a function of cooling rate. The critical rate necessary to achieve a\nvitrification in the mesopores is, however, at least two orders of magnitude\nsmaller than in the bulk state. This finding can be traced both to pure\ngeometrical constraints and quenched disorder effects, characteristic of\nconfinement in mesoporous silicon.",
        "positive": "Flexoelectric effect modeling: The statistical theory of the dipole flexoelectric (FE) polarization in\nliquid crystals is used to calculate the temperature dependence of order\nparameters, the elastic constants and the FE coefficients. Two systems with\npolar wedge-shaped and banana-shaped molecules are investigated. In both cases\nthe FE coefficients are proportional to the dipole moment component parallel to\nthe molecule symmetry axis. The origin of the FE effect and microscopic\npictures of the distorted phases are discussed."
    },
    {
        "anchor": "Charge density dependent nongeminate recombination in organic bulk\n  heterojunction solar cells: Apparent recombination orders exceeding the value of two expected for\nbimolecular recombination have been reported for organic solar cells in various\npublications. Two prominent explanations are bimolecular losses with a carrier\nconcentration dependent prefactor due to a trapping limited mobility, and\nprotection of trapped charge carriers from recombination by a donor--acceptor\nphase separation until reemission from these deep states. In order to clarify\nwhich mechanism is dominant we performed temperature and illumination dependent\ncharge extraction measurements under open circuit as well as short circuit\nconditions at poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C$_{61}$butyric acid\nmethyl ester (P3HT:PC$_{61}$BM) and PTB7:PC$_{71}$BM\n(Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]])\nsolar cells in combination with current--voltage characteristics. We show that\nthe charge carrier density $n$ dependence of the mobility $\\mu$ and the\nrecombination prefactor are different for PC$_{61}$BM at temperatures below\n300K and PTB7:PC$_{71}$BM at room temperature. Therefore, in addition to\n$\\mu(n)$ a detrapping limited recombination in systems with at least partial\ndonor--acceptor phase separation is required to explain the high recombination\norders.",
        "positive": "Random graph approach to multifunctional molecular networks: Formation of a molecular network from multifunctional precursors is modelled\nwith a random graph process. The random graph model favours reactivity for\nmonomers that are positioned close in the network topology, and disfavours\nreactivity for those that are obscured by the surrounding. The phenomena of\nconversion-dependant reaction rates, gelation, and micro-gelation are thus\nnaturally predicted by the model and do not have to be imposed. Resulting\nnon-homogeneous network topologies are analysed to extract such descriptors as:\nsize distribution, crosslink distances, and gel-point conversion. Furthermore,\nnew to the molecular simulation community descriptors are invented. These\ndescriptors are especially useful for understanding evolution of pure gel,\namongst them: cluster coefficient, network modularity, cluster size\ndistribution."
    },
    {
        "anchor": "Oscillatory elastic instabilities in an extensional viscoelastic flow: Dilute polymer solutions are known to exhibit purely elastic instabilities\neven when the fluid inertia is negligible. Here we report the quantitative\nevidence of two consecutive oscillatory elastic instabilities in an elongation\nflow of a dilute polymer solution as realized in a T-junction geometry with a\nlong recirculating cavity. The main result reported here is the observation and\ncharacterization of the first transition as a forward Hopf bifurcation resulted\nin a uniformly oscillating state due to breaking of time translational\ninvariance. This unexpected finding is in contrast with previous experiments\nand numerical simulations performed in similar ranges of the $Wi$ and $Re$\nnumbers, where the forward fork-bifurcation into a steady asymmetric flow due\nto the broken spatial inversion symmetry was reported. We discuss the plausible\ndiscrepancy between our findings and previous studies that could be attributed\nto the long recirculating cavity, where the length of the recirculating cavity\nplays a crucial role in the breaking of time translational invariance instead\nof the spatial inversion. The second transition is manifested via time\naperiodic transverse fluctuations of the interface between the dyed and undyed\nfluid streams at the channel junction and advected downstream by the mean flow.\nBoth instabilities are characterized by fluid discharge-rate and simultaneous\nimaging of the interface between the dyed and undyed fluid streams in the\noutflow channel.",
        "positive": "Isometric immersions, energy minimization and self-similar buckling in\n  non-Euclidean elastic sheets: The edges of torn plastic sheets and growing leaves often display\nhierarchical buckling patterns. We show that this complex morphology (i)\nemerges even in zero strain configurations, and (ii) is driven by a competition\nbetween the two principal curvatures, rather than between bending and\nstretching. We identify the key role of branch-point (or \"monkey-saddle\")\nsingularities in generating complex wrinkling patterns in isometric immersions,\nand show how they arise naturally from minimizing the elastic energy."
    },
    {
        "anchor": "Observation of surface layering in a nonmetallic liquid: Oscillatory density profiles (layers) have previously been observed at the\nfree surfaces of liquid metals, but not in other isotropic liquids. We have\nused x-ray reflectivity to study a molecular liquid,\ntetrakis(2-ethylhexoxy)silane. When cooled to T/Tc~0.25 (well above the\nfreezing point for this liquid), density oscillations appear at the surface.\nLateral order within the layers is liquid-like. Our results confirm theoretical\npredictions that a surface-layered state will appear even in dielectric liquids\nat sufficiently low temperatures, if not preempted by freezing.",
        "positive": "Charge-Fluctuation-Induced Non-analytic Bending Rigidity: In this Letter, we consider a neutral system of mobile positive and negative\ncharges confined on the surface of curved films. This may be an appropriate\nmodel for: i) a highly charged membrane whose counterions are confined to a\nsheath near its surface; ii) a membrane composed of an equimolar mixture of\nanionic and cationic surfactants in aqueous solution. We find that the charge\nfluctuations contribute a non-analytic term to the bending rigidity that varies\nlogarithmically with the radius of curvature. This may lead to spontaneous\nvesicle formation, which is indeed observed in similar systems."
    },
    {
        "anchor": "Colloidal Gelation with Non-Sticky Particles: Colloidal gels are widely applied in industry due to their rheological\ncharacter -- no flow takes place below the yield stress. Such property enables\ngels to maintain uniform distribution in practical formulations; otherwise,\nsolid components may quickly sediment without the support of gel matrix.\nCompared with pure gels of sticky colloids, therefore, the composites of gel\nand non-sticky inclusions are more commonly encountered in reality. Through\nnumerical simulations, we investigate the gelation process in such binary\ncomposites. We find that the non-sticky particles not only confine gelation in\nthe form of an effective volume fraction, but also introduce another\nlengthscale that competes with the size of growing clusters in gel. The ratio\nof two key lengthscales in general controls the two effects. Using different\ngel models, we verify such a scenario within a wide range of parameter space,\nsuggesting a potential universality in all classes of colloidal composites.",
        "positive": "Effective Interactions in Active Brownian Suspensions: Active colloids exhibit persistent motion, which can lead to motility-induced\nphase separation (MIPS). However, there currently exists no microscopic theory\nto account for this phenomenon. We report a first-principles theory, free of\nfit parameters, for active spherical colloids, which shows explicitly how an\neffective many-body interaction potential is generated by activity and how this\ncan rationalize MIPS. For a passively repulsive system the theory predicts\nphase separation and pair correlations in quantitative agreement with\nsimulation. For an attractive system the theory shows that phase separation\nbecomes suppressed by moderate activity, consistent with recent experiments and\nsimulations, and suggests a mechanism for reentrant cluster formation at high\nactivity."
    },
    {
        "anchor": "Anomalous structural and mechanical properties of solids confined in\n  quasi one dimensional strips: We show using computer simulations and mean field theory that a system of\nparticles in two dimensions, when confined laterally by a pair of parallel hard\nwalls within a quasi one dimensional channel, possesses several anomalous\nstructural and mechanical properties not observed in the bulk. Depending on the\ndensity $\\rho$ and the distance between the walls $L_y$, the system shows\nstructural characteristics analogous to a weakly modulated liquid, a strongly\nmodulated smectic, a triangular solid or a buckled phase. At fixed $\\rho$, a\nchange in $L_y$ leads to many reentrant discontinuous transitions involving\nchanges in the number of layers parallel to the confining walls depending\ncrucially on the commensurability of inter-layer spacing with $L_y$. The solid\nshows resistance to elongation but not to shear. When strained beyond the\nelastic limit it fails undergoing plastic deformation but surprisingly, as the\nstrain is reversed, the material recovers completely and returns to its\noriginal undeformed state. We obtain the phase diagram from mean field theory\nand finite size simulations and discuss the effect of fluctuations.",
        "positive": "Network topology in soft gels: hardening and softening materials: The structural complexity of soft gels is at the origin of a versatile\nmechanical response that allows for large deformations, controlled elastic\nrecovery and toughness in the same material. A limit to exploiting the\npotential of such materials is the insufficient fundamental understanding of\nthe microstructural origin of the bulk mechanical properties. Here we\ninvestigate the role of the network topology in a model gel through 3D\nnumerical simulations. Our study links the topology of the network organization\nin space to its non-linear rheological response preceding yielding and damage:\nour analysis elucidates how the network connectivity alone could be used to\nmodify the gel mechanics at large strains, from strain-softening to hardening\nand even to a brittle response. These findings provide new insight for smart\nmaterial design and for understanding the non-trivial mechanical response of a\npotentially wide range of technologically relevant materials."
    },
    {
        "anchor": "Gnomonious Projections for Bend-Free Textures: Thoughts on the\n  Splay-Twist Phase: The Hopf fibration has inspired any number of geometric structures in\nphysical systems, in particular in chiral liquid crystalline materials. Because\nthe Hopf fibration lives on the three sphere, $\\mathbb{S}^3$, some method of\nprojection or distortion must be employed to realize textures in flat space.\nHere, we explore the geodesic-preserving gnomonic projection of the Hopf\nfibration, and show that this could be the basis for a new liquid crystalline\ntexture with only splay and twist. We outline the structure and show that it is\ndefined by the tangent vectors along the straight line rulings on a series of\nhyperboloids. The phase is defined by a lack of bend deformations in the\ntexture, and is reminiscent of the splay-bend and twist-bend nematic phases. We\nshow that domains of this phase may be stabilized through anchoring and\nsaddle-splay.",
        "positive": "The Influence of Thin Film Confinement on Surface Plasticity in\n  Polystyrene and Poly(2-vinylpyridine) Homopolymer and Block Copolymer Films: Thin block copolymer films have attracted considerable academic attention\nbecause of their ability to self-assemble into various microstructures, many of\nwhich have potential technological applications. Despite the ongoing interest,\nlittle effort has focused on the onset of plasticity and failure which are\nimportant factors for the eventual adoption of these materials. Here we use\ndelamination to impart a quantifiable local stain on thin films of homopolymer\npolystyrene and poly(2-vinylpyridine), as well as block copolymers made of\nstyrene and 2-vinylpyridine. Direct observation of the damage caused by bending\nwith atomic force microscopy and laser scanning confocal microscopy, leads to\nthe identification of a critical strain for the onset of plasticity. Moving\nbeyond our initial scaling analysis, the more quantitative analysis presented\nhere shows strain levels for thick films to be comparable to bulk measurements.\nMonitoring the critical strain leads to several observations: 1.) as-cast\nPS-P2VP has low critical strain, 2.) annealing slowly increases critical strain\nas microstructural ordering takes place, and 3.) similar to the homopolymer,\nboth as cast and ordered films both show increasing critical strain under\nconfinement."
    },
    {
        "anchor": "Structural alignment using the generalized Euclidean distance between\n  conformations: The usual Euclidean distance may be generalized to extended objects such as\npolymers or membranes. Here, this distance is used for the first time as a cost\nfunction to align structures. We examined the alignment of extended strands to\nidealized beta-hairpins of various sizes using several cost functions,\nincluding RMSD, MRSD, and the minimal distance. We find that using minimal\ndistance as a cost function typically results in an aligned structure that is\nglobally different than that given by an RMSD-based alignment",
        "positive": "Competing quantum effects in the dynamics of a flexible water model: Numerous studies have identified large quantum mechanical effects in the\ndynamics of liquid water. In this paper, we suggest that these effects may have\nbeen overestimated due to the use of rigid water models and flexible models in\nwhich the intramolecular interactions were described using simple harmonic\nfunctions. To demonstrate this, we introduce a new simple point charge model\nfor liquid water, q-TIP4P/F, in which the O--H stretches are described by\nMorse-type functions. We have parameterized this model to give the correct\nliquid structure, diffusion coefficient, and infra-red absorption frequencies\nin quantum (path integral-based) simulations. By comparing classical and\nquantum simulations of the liquid, we find that quantum mechanical fluctuations\nincrease the rates of translational diffusion and orientational relaxation in\nour model by a factor of around 1.15. This effect is much smaller than that\nobserved in all previous simulations of simple empirical water models, which\nhave found a quantum effect of at least 1.4 regardless of the quantum\nsimulation method or the water model employed. The small quantum effect in our\nmodel is a result of two competing phenomena. Intermolecular zero point energy\nand tunneling effects destabilize the hydrogen bonding network, leading to a\nless viscous liquid with a larger diffusion coefficient. However this is offset\nby intramolecular zero point motion, which changes the average water monomer\ngeometry resulting in a larger dipole moment, stronger intermolecular\ninteractions, and slower diffusion. We end by suggesting, on the basis of\nsimulations of other potential energy models, that the small quantum effect we\nfind in the diffusion coefficient is associated with the ability of our model\nto produce a single broad O-H stretching band in the infra-red absorption\nspectrum."
    },
    {
        "anchor": "Stability criterion for fresh cement foams: We prepare and study cement foam samples with well-controlled structure, i.e.\ncontaining monodisperse bubbles. We observe that the foam structure often\nchanges before cement setting and identify ripening as the major\ndestabilization mechanism at stake. Drainage plays only a minor role in cement\nfoam destabilization except when bubble size is large. Then we show that a\nsingle stability criterion can be defined, for a large range of cement foams\nwith different formulations. This criterion involves the bubble radius and the\nyield stress of the cement paste such as confined by and between the bubbles,\nat a given characteristic time after sample preparation.",
        "positive": "Viscosity Overshoot in Biaxial Elongational Flow: Coarse-Grained\n  Molecular Dynamics Simulation of Ring-Linear Polymer Mixtures: Viscosity overshoot of entangled polymer melts has been observed under shear\nflow and uniaxial elongational flow, but has never been observed under biaxial\nelongational flow. We confirmed the presence of viscosity overshoot under\nbiaxial elongational flows observed in a mixed system of ring and linear\npolymers expressed by coarse-grained molecular dynamics simulations. The\novershoot was found to be more pronounced in weakly entangled melts.\nFurthermore, the threshold strain rate $\\dot{\\varepsilon}_{\\rm th}$\ndistinguishing linear and nonlinear behaviors was found to be dependent on the\nlinear chain length as $\\dot{\\varepsilon}_{\\rm th}(N)\\sim N^{-1/2}$, which\ndiffers from the conventional relationship, $\\dot{\\varepsilon}_{\\rm th}(N) \\sim\nN^{-2}$, expected from the inverse of the Rouse relaxation time. We have\nconcluded that the cooperative interactions between rings and linear chains\nwere enhanced under biaxial elongational flow."
    },
    {
        "anchor": "Simulating flexible polymers in a potential of randomly distributed hard\n  disks: We perform equilibrium computer simulations of a two-dimensional pinned\nflexible polymer exposed to a quenched disorder potential consisting of hard\ndisks. We are especially interested in the high-density regime of the disorder,\nwhere subtle structures such as cavities and channels play a central role. We\napply an off-lattice growth algorithm proposed by Garel and Orland [J. Phys. A\n23, L621 (1990)], where a distribution of polymers is constructed in parallel\nby growing each of them monomer by monomer. In addition we use a multicanonical\nMonte Carlo method in order to cross-check the results of the growth algorithm.\nWe measure the end-to-end distribution and the tangent-tangent correlations. We\nalso investigate the scaling behavior of the mean square end-to-end distance in\ndependence of the monomer number. While the influence of the potential in the\nlow-density case is merely marginal, it dominates the configurational\nproperties of the polymer for high densities.",
        "positive": "Selectively Controlled Magnetic Microrobots with Opposing Helices: Magnetic microrobots that swim through liquid media are of interest for\nminimally invasive medical procedures, bioengineering, and manufacturing. Many\nof the envisaged applications, such as micromanipulation and targeted cargo\ndelivery, necessitate the use and adequate control of multiple microrobots,\nwhich will increase the velocity, robustness, and efficacy of a procedure.\nWhile various methods involving heterogeneous geometries, magnetic properties,\nand surface chemistries have been proposed to enhance independent control, the\nmain challenge has been that the motion between all microwsimmers remains\ncoupled through the global control signal of the magnetic field. Katsamba and\nLauga proposed transchiral microrobots, a theoretical design with magnetized\nspirals of opposite handedness. The competition between the spirals can be\ntuned to give an intrinsic nonlinearity that each device can function only\nwithin a given band of frequencies. This allows individual microrobots to be\nselectively controlled by varying the frequency of the rotating magnetic field.\nHere we present the experimental realization and characterization of\ntranschiral micromotors composed of independently driven magnetic helices. We\nshow a swimming micromotor that yields negligible net motion until a critical\nfrequency is reached and a micromotor that changes its translation direction as\na function of the frequency of the rotating magnetic field. This work\ndemonstrates a crucial step towards completely decoupled and addressable\nswimming magnetic microrobots."
    },
    {
        "anchor": "Hydrophobic Polyelectrolytes in Better Polar Solvent. Structure and\n  Chain Conformation as seen by Saxs and Sans: We demonstrate in this paper the influence of solvent quality on the\nstructure of the semi-dilute solution of a hydrophobic polyelectrolyte,\npartially sulfonated Poly-Styrene Sulfonate. Two solvents are used: (i) one\nmixture of water and an organic solvent: THF, which is also slightly polar;\n(ii) DMSO, a polar organic solvent. In case (i), it is shown by SAXS study that\nthe structure - namely the scattering from all chains, characterised by a\nmaximum (\"polyelectrolyte peak\"), of the aqueous hydrophobic polyelectrolyte\nsolutions (PSS) depends on the solvent quality through the added amount of\norganic solvent THF. This dependence is more pronounced when the sulfonation\nrate is low (more hydrophobic polyelectrolyte). It is proposed that when THF is\nadded, the chain conformation evolves from the pearl necklace shape already\nreported in pure water, towards the conformation in pure water for fully\nsulfonated PSS, which is string-like as also reported previously. On the\ncontrary, for a hydrophilic polyelectrolyte, AMAMPS, no evolution occurs with\nadded THF in the aqueous solution. In case (ii), it is shown directly by SANS\nstudy that PSS can behave as a classical solvophilic polyelectrolyte when\ndissolved in an organic polar solvent such as DMSO: the structure (total\nscattering) as well as the form factor (single chain scattering measured by\nSANS using the Zero Average Contrast method) of the PSS chains is independent\nof the charge content in agreement with Manning condensation, and identical to\nthe one of a fully charged PSS chain in pure water, which has a classical\npolyelectrolyte behaviour in the semi-dilute regime.",
        "positive": "Aging and rejuvenation during elastostatic loading of amorphous alloys: Using molecular dynamics simulations, we investigate the effect of uniaxial\nelastostatic compression on the potential energy, structural relaxation, and\nmechanical properties of binary glasses. We consider the three-dimensional\nKob-Andersen binary mixture, which was initially cooled from the liquid state\nto the glass phase with a slow rate at zero pressure. The glass was then loaded\nwith a static stress at the annealing temperature during extended time\nintervals. It is found that the static stress below the yielding point induces\nlarge-scale plastic deformation and significant rejuvenation when the annealing\ntemperature is smaller than a fraction of the glass transition temperature. By\ncontrast, aging effects become dominant at sufficiently small values of the\nstatic stress and higher annealing temperatures. The mechanical tests after the\nelastostatic compression have shown that both the elastic modulus and the yield\nstress decrease in rejuvenated samples, while the opposite trend was observed\nfor relaxed glasses. These results might be useful for the thermomechanical\nprocessing of metallic glasses with optimized mechanical properties."
    },
    {
        "anchor": "Phase separation dynamics in a two-dimensional magnetic mixture: Based on classical density functional theory (DFT), we investigate the\ndemixing phase transition of a two-dimensional, binary Heisenberg fluid\nmixture. The particles in the mixture are modeled as Gaussian soft spheres,\nwhere one component is characterized by an additional classical spin-spin\ninteraction of Heisenberg type. Within the DFT we treat the particle\ninteractions using a mean-field approximation. For certain magnetic coupling\nstrengths we calculate phase diagrams in the density-concentration plane. For\nsufficiently large coupling strengths and densities, we find a demixing phase\ntransition driven by the ferromagnetic interactions of the magnetic species. We\nalso provide a microscopic description (i.e., density profiles) of the\nresulting non-magnetic/magnetic fluid-fluid interface. Finally, we investigate\nthe phase separation using dynamical density functional theory (DDFT),\nconsidering both nucleation processes and spinodal demixing.",
        "positive": "On the Packing of Stiff Rods on Ellipsoids Part II -- Entropy and Self\n  Avoidance: Using a statistical - mechanics approach, we study the effects of geometry\nand entropy on the ordering of slender filaments inside non-isotropic\ncontainers, considering cortical microtubules in plant cells, and packing of\ngenetic material inside viral capsids as concrete examples. Working in a mean -\nfield approximation, we show analytically how the shape of container, together\nwith self avoidance, affects the ordering of stiff rods. We find that the\nstrength of the self-avoiding interaction plays a significant role in the\npreferred packing orientation, leading to a first-order transition for oblate\ncells, where the preferred orientation changes from azimuthal, along the\nequator, to a polar one, when self avoidance is strong enough. While for\nprolate spheroids the ground state is always a polar like order, strong self\navoidance result with a deep meta-stable state along the equator. We compute\nthe critical surface describing the transition between azimuthal and polar\nordering in the three dimensional parameter space (persistence length,\ncontainer shape, and self avoidance) and show that the critical behavior of\nthis systems, in fact, relates to the butterfly catastrophe model. We compare\nthese results to the pure mechanical study in arXiv:1910.08171, and discuss\nsimilarities and differences. We calculate the pressure and shear stress\napplied by the filament on the surface, and the injection force needed to be\napplied on the filament in order to insert it into the volume"
    },
    {
        "anchor": "Use Adaptive Fast Function Approximator in Motor-Filament Binding\n  Kinetics: The cytoskeleton, consisting of biopolymer filaments, molecular motors, and\npassive crosslinking proteins, provides the internal structure of cells that\nfacilitate movement, growth, and cell division. Understanding the microscopic\nmotor-filament kinetics and dynamics is essential for comprehending macroscopic\nbehaviors of reconstituted cytoskeletal assemblies, such as self-organized flow\nand active stress. In this study, we employ an adaptive fast Chebyshev\napproximation based on tree search alongside parallel computing to accurately\nrecover the equilibrium distribution of crosslinking proteins, thus satisfying\ndetailed balance in binding through kinetic Monte Carlo sampling, while\nmaintaining cost-effectiveness. Additionally, we offer expandable features,\nincluding segregating the simulation process via pre-building and allowing the\nfree-loading of different explicit formulations of the motor's potential\nenergy. This research has the potential to better describe the evolution of\ncytoskeletal active matter.",
        "positive": "Spontaneous rotation can stabilise ordered chiral active fluids: Active hydrodynamic theories are a powerful tool to study the emergent\nordered phases of internally driven particles such as bird flocks, bacterial\nsuspension and their artificial analogues. While theories of orientationally\nordered phases are by now well established, the effect of chirality on these\nphases is much less studied. In this paper, we present the first complete\ndynamical theory of orientationally ordered chiral particles in two-dimensional\nincompressible systems. We show that phase-coherent states of rotating chiral\nparticles are remarkably stable in both momentum-conserved and non-conserved\nsystems in contrast to their non-rotating counterparts. Furthermore, defect\nseparation -- which drives chaotic flows in non-rotating active fluids -- is\nsuppressed by intrinsic rotation of chiral active particles. We thus establish\nchirality as a source of dramatic stabilization in active systems, which could\nbe key in interpreting the collective behaviours of some biological tissues,\ncytoskeletal systems and collections of bacteria."
    },
    {
        "anchor": "Temporal and spatial heterogeneity in aging colloids: a mesoscopic model: A coarse-grained model of dense hard sphere colloids building on simple\nnotions of particle mobility and spatial coherence is presented and shown to\nreproduce results of experiments and simulations for key quantities such as the\nintermediate scattering function, the particle mean-square displacement and the\n$\\chi_{4}$ mobility correlation function. All results are explained by two\nemerging and interrelated dynamical properties: i) a rate of intermittent\nevents, quakes, which decreases as the inverse of the system age t; ii) a\nlength scale characterizing correlated domains, which increases linearly in log\nt. This leads to simple and accurate scaling forms expressed in terms of a\nsingle scaling variable Finally, we propose a method to experimentally extract\nthe growing length scale of an aging colloid and suggest that a suitable\nscaling of the probability density function of particle displacement can\nexperimentally reveal the rate of quakes.",
        "positive": "Memory formation in dense persistent active matter: Protocol-dependent states in structural glasses can encode a disordered, yet\nretrievable memory. While training such materials is typically done via a\nglobal drive, such as external shear, in dense active matter the driving is\ninstead local and spatio-temporally correlated. Here we focus on the impact of\nsuch spatial correlation on memory formation. We investigate the mechanical\nresponse of a dense amorphous packing of athermal particles, subject to an\noscillatory quasistatic driving with a tunable spatial correlation, akin to the\ninstantaneous driving pattern in active matter. We find that the capacity to\nencode memory can be rendered comparable upon a proper rescaling on the spatial\ncorrelation, whereas the efficiency in memory formation increases with motion\ncooperativity."
    },
    {
        "anchor": "How Surface Roughness Affects the Interparticle Interactions at a Liquid\n  Interface: Shapes of colloids matter at liquid interfaces. We explore the interactions\nbetween rough-surfaced nanocolloids at the air--water interface through the\ncompaction of monolayers experimentally and numerically. Sufficiently rough\nsystems exhibit a non-trivial intermediate state between a gas-like state and a\nclose-packed jamming state due to roughness-induced capillary attraction. We\nalso find that roughness-induced friction lowers the jamming point, and the\ntangential contact force owing to surface asperities can cause a gradual\noff-plane collapse of the compressed monolayer.",
        "positive": "Artificial Neural Networks for Predicting Mechanical Properties of\n  Crystalline Polyamide12 via Molecular Dynamics Simulations: Predicting material properties of 3D printed polymer products is a challenge\nin additive manufacturing due to the highly localized and complex manufacturing\nprocess. The microstructure of such products is fundamentally different from\nthe ones obtained by using conventional manufacturing methods, which makes the\ntask even more difficult. As a first step of a systematic multiscale approach,\nin this work, we have developed an artificial neural network (ANN) to predict\nthe mechanical properties of the crystalline form of Polyamide12 (PA12) based\non data collected from molecular dynamics (MD) simulations. Using the machine\nlearning approach, we are able to predict the stress-strain relations of PA12\nonce the macroscale deformation gradient is provided as an input to the ANN. We\nhave shown that this is an efficient and accurate approach, which can provide a\nthree-dimensional molecular-level anisotropic stress-strain relation of PA12\nfor any macroscale mechanics model, such as finite element modeling at\narbitrary quadrature points. This work lays the foundation for a multiscale\nfinite element method for simulating semicrystalline polymers, which will be\npublished as a separate study."
    },
    {
        "anchor": "Overdamped van Hove function of atomic liquids: Using the generalized Langevin equation formalism and the process of\ncontraction of the description we derive a general memory function equation for\nthe thermal fluctuations of the local density of a simple atomic liquid. From\nthe analysis of the long-time limit of this equation, a striking equivalence is\nsuggested between the long-time dynamics of the atomic liquid and the dynamics\nof the corresponding \\emph{Brownian} liquid. This dynamic equivalence is\nconfirmed here by comparing molecular and Brownian dynamics simulations of the\nself-intermediate scattering function and the long-time self-diffusion\ncoefficient for the hard-sphere liquid.",
        "positive": "Force-induced elastic matrix-mediated interactions in the presence of a\n  rigid wall: We consider an elastic composite material containing particulate inclusions\nin a soft elastic matrix that is bounded by a rigid wall, e.g., the substrate.\nIf such a composite serves as a soft actuator, forces are imposed on or induced\nbetween the embedded particles. We investigate how the presence of the rigid\nwall affects the interactions between the inclusions in the elastic matrix. For\nno-slip boundary conditions, we transfer Blake's derivation of a corresponding\nGreen's function from low-Reynolds-number hydrodynamics to the linearly elastic\ncase. Results for no-slip and free-slip surface conditions are compared to each\nother and to the bulk behavior. Our results suggest that walls with free-slip\nsurface conditions are preferred when they serve as substrates for soft\nactuators made from elastic composite materials. As we further demonstrate, the\npresence of a rigid wall can qualitatively change the interactions between the\ninclusions. In effect, it can switch attractive interactions into repulsive\nones (and vice versa). It should be straightforward to observe the effects in\nfuture experiments and to combine our results, e.g., with the modeling of\nbiological cells and tissue on rigid surfaces."
    },
    {
        "anchor": "Compaction and dilation rate dependence of stresses in gas-fluidized\n  beds: A particle dynamics-based hybrid model, consisting of monodisperse spherical\nsolid particles and volume-averaged gas hydrodynamics, is used to study\ntraveling planar waves (one-dimensional traveling waves) of voids formed in\ngas-fluidized beds of narrow cross sectional areas. Through ensemble-averaging\nin a co-traveling frame, we compute solid phase continuum variables (local\nvolume fraction, average velocity, stress tensor, and granular temperature)\nacross the waves, and examine the relations among them. We probe the\nconsistency between such computationally obtained relations and constitutive\nmodels in the kinetic theory for granular materials which are widely used in\nthe two-fluid modeling approach to fluidized beds. We demonstrate that solid\nphase continuum variables exhibit appreciable ``path dependence'', which is not\ncaptured by the commonly used kinetic theory-based models. We show that this\npath dependence is associated with the large rates of dilation and compaction\nthat occur in the wave. We also examine the relations among solid phase\ncontinuum variables in beds of cohesive particles, which yield the same path\ndependence. Our results both for beds of cohesive and non-cohesive particles\nsuggest that path-dependent constitutive models need to be developed.",
        "positive": "Mechanical unfolding of a homopolymer globule studied by self-consistent\n  field modelling: We present results of numerical self-consistent field (SCF) calculations for\nthe equilibrium mechanical unfolding of a globule formed by a single flexible\npolymer chain collapsed in a poor solvent. In accordance with earlier scaling\ntheory and stochastic dynamics simulations findings we have identified three\nregimes of extensional deformation: (i) a linear response regime characterized\nby a weakly elongated (ellipsoidal) shape of the globule at small deformations,\n(ii) a tadpole structure with a globular \"head\" coexisting with a stretched\n\"tail\" at intermediate ranges of deformations, and (iii) an uniformly stretched\nchain at strong extensions. The conformational transition from the tadpole to\nthe stretched chain is accompanied by an abrupt unfolding of the depleted\nglobular head and a corresponding jump-wise drop in the intrachain tension. The\nunfolding-refolding cycle demonstrates a hysteresis loop in the vicinity of the\ntransition point. These three regimes of deformation, as well as the\nfirst-order like transition between the tadpole and the stretched chain\nconformations, can be experimentally observable provided that the number of\nmonomer units in the chain is large and/or the solvent quality is sufficiently\npoor. For short chains, on the other hand, under moderately poor solvent\nstrength conditions, the unfolding transition is continuous. Upon an increase\nin the imposed end-to-end distance the extended globule retains a\nlongitudinally uniform shape at any degree of deformation. In all cases the\nsystem exhibits a negative extensional modulus in the intermediate range of\ndeformations. We anticipate that predicted patterns in force-deformation curves\nfor polymer molecules in poor solvent can be observed in single molecule atomic\nspectroscopy experiments."
    },
    {
        "anchor": "Stretching Instability of Helical Spring: We show that when a gradually increasing tensile force is applied to the ends\nof a helical spring with sufficiently large ratios of radius to pitch and twist\nto bending rigidity, the end-to-end distance undergoes a sequence of\ndiscontinuous stretching transitions. Subsequent decrease of the force leads to\nstep-like contraction and hysteresis is observed. For finite helices, the\nnumber of these transitions increases with the number of helical turns but only\none stretching and one contraction instability survive in the limit of an\ninfinite helix. We calculate the critical line that separates the region of\nparameters in which the deformation is continuous from that in which stretching\ninstabilities occur, and propose experimental tests of our predictions.",
        "positive": "Variational field theory of macroscopic forces in Coulomb fluids: Based on the variational field theory framework, we extend our previous\nmean-field formalism, taking into account the electrostatic correlations of the\nions. We employ a general covariant approach and derive a total stress tensor\nthat considers the electrostatic correlations of ions. This is accomplished\nthrough an additional term that depends on the autocorrelation function of\nlocal electric field fluctuations. Utilizing the derived total stress tensor\nand applying the mechanical equilibrium condition, we establish a general\nexpression for the disjoining pressure of the Coulomb fluids, confined in a\npore with a slit-like geometry. Using this equation, we derive an asymptotic\nexpression for the disjoining pressure in a slit-like pore with non-electrified\nconductive walls. Present theory is the basis for future modeling of the\nmechanical stresses that occur in electrode pores with conductive charged\nwalls, immersed in liquid phase electrolytes beyond the mean-field theory."
    },
    {
        "anchor": "Nondiffusive heat transfer in muscle tissue. Preliminary results: We present preliminary experimental data that enable us to suggest that heat\ntransfer in cellular tissue under local strong heating is a more complex\nphenomenon than a simple heat diffusion. Namely, we demonstrate that under\nlocal strong heating of a muscle tissue heat transfer in it exhibits\nsubstantial anisotropy unexplained in the context of the standard diffusion\nmodel. The observed temperature dynamics is also characterized by nonlinear\nbehavior as well as by a certain repeat reversibility. The latter means that\nthe time variations in the temperature of a cellular tissue undergoing repeated\nacts of heating go in the same way at least approximately. We explain the\nobserved anomalous properties of heat transfer by suggesting the flow of the\ninterstitial liquid to appear due to nonuniform heating which, in turn, affects\nthe heat transfer. A possible mechanism responsible for this effect is\ndiscussed.",
        "positive": "Stress Tensors of Multiparticle Collision Dynamics Fluids: Stress tensors are derived for the multiparticle collision dynamics\nalgorithm, a particle-based mesoscale simulation method for fluctuating fluids,\nresembling those of atomistic or molecular systems. Systems with periodic\nboundary conditions as well as fluids confined in a slit are considered. For\nevery case, two equivalent expressions for the tensor are provided, the\ninternal stress tensor, which involves all degrees of freedom of a system, and\nthe external stress, which only includes the interactions with the confining\nsurfaces. In addition, stress tensors for a system with embedded particles are\ndetermined. Based on the derived stress tensors, analytical expressions are\ncalculated for the shear viscosity. Simulations illustrate the difference in\nfluctuations between the various derived expressions and yield very good\nagreement between the numerical results and the analytically derived expression\nfor the viscosity."
    },
    {
        "anchor": "Coarse-grained molecular dynamics simulation of binary charged lipid\n  membranes: Phase separation and morphological dynamics: Biomembranes, which are mainly composed of neutral and charged lipids,\nexhibit a large variety of functional structures and dynamics. Here, we report\na coarse-grained molecular dynamics (MD) simulation of the phase separation and\nmorphological dynamics in charged lipid bilayer vesicles. The screened\nlong-range electrostatic repulsion among charged head groups delays or inhibits\nthe lateral phase separation in charged vesicles compared with neutral\nvesicles, suggesting the transition of the phase-separation mechanism from\nspinodal decomposition to nucleation or homogeneous dispersion. Moreover, the\nelectrostatic repulsion causes morphological changes, such as pore formation,\nand further transformations into disk, string, and bicelle structures, which\nare spatiotemporally coupled to the lateral segregation of charged lipids.\nBased on our coarse-grained MD simulation, we propose a plausible mechanism of\npore formation at the molecular level. The pore formation in a\ncharged-lipid-rich domain is initiated by the prior disturbance of the local\nmolecular orientation in the domain.",
        "positive": "Energetics of twisted elastic filament pairs: We investigate the elastic energy stored in a filament pair as a function of\napplied twist by measuring torque under prescribed end-to-end separation\nconditions. We show that the torque increases rapidly to a peak with applied\ntwist when the filaments are initially separate, then decreases to a minimum as\nthe filaments cross and come into contact. The torque then increases again\nwhile the filaments form a double helix with increasing twist. A nonlinear\nelasto-geometric model that combines the effect of geometrical nonlinearities\nwith large stretching and self-twist is shown to capture the evolution of the\nhelical geometry, the torque profile, and the stored energy with twist. We find\nthat a large fraction of the total energy is stored in stretching the\nfilaments, which increases with separation distance and applied tension. We\nfind that only a small fraction of energy is stored in the form of bending\nenergy, and that the contribution due to contact energy is negligible. Our\nstudy highlights the consequences of stretchablility on filament twisting which\nis a fundamental topological transformation relevant to making ropes, tying\nshoelaces, actuating robots, and the physical properties of entangled polymers."
    },
    {
        "anchor": "Analytic analysis of auxetic metamaterials through analogy with rigid\n  link systems: Recent progress in advanced additive manufacturing techniques has stimulated\nthe growth of the field of mechanical metamaterials. One area particular\ninterest in this subject is the creation of auxetic material properties through\nelastic instability. This paper focuses on a novel methodology in the analysis\nof auxetic metamaterials through analogy with rigid link lattice systems. Our\nanalytic methodology gives extremely good agreement with finite element\nsimulations for both the onset of elastic instability and post-buckling\nbehaviour including Poisson's ratio. The insight into the relationships between\nmechanisms within lattices and their mechanical behaviour has the potential to\nguide the rational design of lattice based metamaterials.",
        "positive": "Structure factor and thermodynamics of rigid dendrimers in solution: The ''polymer reference interaction site model'' (PRISM) integral equation\ntheory is used to determine the structure factor of rigid dendrimers in\nsolution. The theory is quite successful in reproducing experimental structure\nfactors for various dendrimer concentrations. In addition, the structure factor\nat vanishing scattering vector is calculated via the compressibility equation\nusing scaled particle theory and fundamental measure theory. The results as\npredicted by both theories are systematically smaller than the experimental and\nPRISM data for platelike dendrimers."
    },
    {
        "anchor": "The Local Compressibility of Liquids near Non-Adsorbing Substrates: A\n  Useful Measure of Solvophobicity and Hydrophobicity?: We investigate the suitability of the local compressibility chi(z) as a\nmeasure of the solvophobicity or hydrophobicity of a substrate. Defining the\nlocal compressibility as the derivative of the local one-body density w.r.t.\nthe chemical potential at fixed temperature, we use density functional theory\n(DFT) to calculate chi(z) for a model fluid, close to bulk liquid-gas\ncoexistence, at various planar substrates. These range from a `neutral'\nsubstrate with a contact angle of approximately 90 degrees, which favours\nneither the liquid nor the gas phase, to a very solvophobic, purely repulsive\nsubstrate which exhibits complete drying (i.e. contact angle 180 degrees). We\nfind that the maximum in the local compressibility, which occurs within one-two\nmolecular diameters of the substrate, and the integrated quantity chi_ex (the\nsurface excess compressibility, defined below) both increase rapidly as the\ncontact angle increases and the substrate becomes more solvophobic. The local\ncompressibility provides a more pronounced indicator of solvophobicity than the\ndensity depletion in the vicinity of the surface which increases only weakly\nwith increasing contact angle. When the fluid is confined in a parallel slit\nwith two identical solvophobic walls, or with competing solvophobic and\nsolvophilic walls, chi(z) close to the solvophobic wall is altered little from\nthat at the single substrate. We connect our results with simulation studies of\nwater near to hydrophobic surfaces exploring the relationship between chi(z)\nand fluctuations in the local density and between chi_ex and the mean-square\nfluctuation in the number of adsorbed molecules.",
        "positive": "Experimental Test of the validity of \"Isotropic\" Approximation for the\n  Mechanical Behaviour of Clay: Experimental data from axially symmetric compression test at constant mean\npressure p on kaolinite clay are used to study the validity of an \"isotropic\"\nmodelling as a function of the overconsolidation ratio (OCR).The isotropic\nassumption is found to be quite good for 2<OCR<3 and/or in the range of small\ndeformation for OCR>4. For very large OCR (OCR >10), anisotropic response is\nobserved at few percents of axial deformation. Relation with anisotropic\ndistribution of local forces is made. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn"
    },
    {
        "anchor": "Dewetting Characteristics of Contact Lenses Coated with Wetting Agents: Hypothesis:\n  Although wetting agents have been developed to limit tear film dewetting over\ncontact lenses, systematic analyses correlating wetting agents properties to\nmechanisms of the tear film destabilization are not readily available.\nClarifying destabilization characteristics across key physio-chemical variables\nwill provide a rational basis for identifying optimal wetting agents.\n  Experiments:\n  We employ an in-house, in vitro platform to comprehensively evaluate drainage\nand dewetting dynamics of five wetting agents across seventeen different\nformulations and two model tear film solutions: phosphate-buffered saline (PBS)\nand artificial tear solution (ATS). We consider the film thickness evolution,\nfilm thickness at breakup, dewetted front propagation, and develop correlations\nto contact angle to compare the samples.\n  Findings:\n  Zwitterionic wetting agents effectively stabilize the tear film by reducing\nthe film thickness at the onset of dewetting, and delaying dewetted region\npropagation across the lens. Furthermore, tuning wetting agent surface\nconcentrations in binary mixtures can enhance wetting characteristics. Finally,\ndespite disparities in wetting agent molecular properties, the time to dewet\n$50\\%$ of the lens scales linearly with the product of the receding contact\nangle and contact angle hysteresis. Hence, we fundamentally establish the\nimportance of minimizing both the absolute contact angle values and contact\nangle hysteresis for effective wetting performance.",
        "positive": "A comparison of limited-stretch models of rubber elasticity: In this paper we describe various limited-stretch models of nonlinear rubber\nelasticity, each dependent on only the first invariant of the left Cauchy-Green\nstrain tensor and having only two independent material constants. The models\nare described as limited-stretch, or restricted elastic, because the strain\nenergy and stress response become infinite at a finite value of the first\ninvariant. These models describe well the limited stretch of the polymer chains\nof which rubber is composed. We discuss Gent's model which is the simplest\nlimited-stretch model and agrees well with experiment. Various statistical\nmodels are then described: the one-chain, three-chain, four-chain and\nArruda-Boyce eight-chain models, all of which involve the inverse Langevin\nfunction. A numerical comparison between the three-chain and eight-chain models\nis provided. Next, we compare various models which involve approximations to\nthe inverse Langevin function with the exact inverse Langevin function of the\neight-chain model. A new approximate model is proposed that is as simple as\nCohen's original model but significantly more accurate. We show that\neffectively the eight-chain model may be regarded as a linear combination of\nthe neo-Hookean and Gent models. Treloar's model is shown to have about half\nthe percentage error of our new model but it is much more complicated. For\ncompleteness a modified Treloar model is introduced but this is only slightly\nmore accurate than Treloar's original model. For the deformations of uniaxial\ntension, biaxial tension, pure shear and simple shear we compare the accuracy\nof these models, and that of Puso, with the eight-chain model by means of\ngraphs and a table. Our approximations compare extremely well with models\nfrequently used and described in the literature, having the smallest mean\npercentage error over most of the range of the argument."
    },
    {
        "anchor": "Mobility and diffusion of intruders in granular suspensions. Einstein\n  relation: The Enskog kinetic equation is considered to determine the mobility $\\lambda$\nand diffusion $D$ transport coefficients of intruders immersed in a granular\ngas of inelastic hard spheres (grains). Intruders and grains are in contact\nwith a thermal bath, which plays the role of a background gas. As usual, the\ninfluence of the latter on the dynamics of intruders and grains is accounted\nfor via a viscous drag force plus a stochastic Langevin-like term proportional\nto the background temperature $T_\\text{b}$. The transport coefficients\n$\\lambda$ and $D$ are determined by solving the kinetic equation by means of\nthe Chapman--Enskog method adapted to dissipative dynamics. Both transport\ncoefficients are given in terms of the solutions of two integral equations\nwhich are approximately solved up to the second order in a Sonine polynomial\nexpansion. Theoretical results are compared against numerical solutions of the\ninelastic Enskog equation by means of the direct simulation Monte Carlo (DSMC)\nmethod. Good agreement between theory and simulations is in general found,\nspecially in the case of the second Sonine approximation. The knowledge of the\ncoefficients $\\lambda$ and $D$ allow us to assess the departure of the Einstein\nrelation $\\epsilon=D/(T_{\\text{b}}\\lambda)$ from 1. As expected from previous\nresults for driven granular gases, it is shown that the origin of the deviation\nof $\\epsilon$ from 1 is only due to the non-Maxwellian behavior of reference\nstate of intruders (measured by the cumulant $c_0$) when the bath temperature\n$T_\\text{b}$ is replaced by the intruder temperature $T_0$ in the Einstein\nrelation. Since the magnitude of $c_0$ is in general very small, deviations of\nthe (modified) Einstein relation $\\epsilon_0=D/(T_0\\lambda)$ from 1 cannot be\ndetected in computer simulations of dilute granular gases. This conclusion\nagrees well with previous computer simulation results.",
        "positive": "Stokesian dynamics of pill-shaped Janus particles with stick and slip\n  boundary conditions: We study the forces and torques experienced by pill-shaped Janus particles of\ndifferent aspect ratios where half of the surface obeys the no-slip boundary\ncondition and the other half obeys the Navier slip condition of varying slip\nlengths. Using a recently developed boundary integral formulation whereby the\ntraditional singular behaviour of this approach is removed analytically, we\nquantify the strength of the forces and torques experienced by such particles\nin a uniform flow field in the Stokes regime. Depending on the aspect ratio and\nthe slip length, the force transverse to the flow direction can change sign.\nThis is a novel property unique to the Janus nature of the particles."
    },
    {
        "anchor": "Constraints on fundamental physical constants from bio-friendly\n  viscosity and diffusion: The problem of understanding fundamental physical constants was discussed in\nparticle physics, astronomy and cosmology. Here, I show that a new insight\ncomes from condensed matter physics and liquid physics in particular:\nfundamental constants have a bio-friendly window constrained by bio-friendly\nviscosity and diffusion setting the motion in essential life processes in and\nacross cells. I also show that bounds on viscosity, diffusion and the\nfundamental velocity gradient in a biochemical machine can all be varied while\nkeeping the fine-structure constant and the proton-to-electron mass ratio\nintact, with no implication for the production of heavy nuclei in stars. This\nleads to a conjecture of multiple tuning and an evolutionary mechanism.",
        "positive": "From Elasticity to Hypoplasticity: Dynamics of Granular Solids: \"Granular elasticity,\" useful for calculating static stress distributions in\ngranular media, is generalized by including the effects of slowly moving,\ndeformed grains. The result is a hydrodynamic theory for granular solids that\nagrees well with models from soil mechanics."
    },
    {
        "anchor": "Staggered Ladder Spectra: We exactly solve a Fokker-Planck equation by determining its eigenvalues and\neigenfunctions: we construct nonlinear second-order differential operators\nwhich act as raising and lowering operators, generating ladder spectra for the\nodd and even parity states. These are staggered: the odd-even separation\ndiffers from even-odd. The Fokker-Planck equation describes, in the limit of\nweak damping, a generalised Ornstein-Uhlenbeck process where the random force\ndepends upon position as well as time. Our exact solution exhibits anomalous\ndiffusion at short times and a stationary non-Maxwellian momentum distribution.",
        "positive": "Arrest of three-dimensional gravity-confined shear flow of wet granular\n  matter: We study the arrest of three-dimensional flow in wet granular matter subject\nto a sinusoidal external force and a gravitational field confining the flow in\nthe vertical direction. The minimal strength of the external force that is\nrequired to keep the system in motion is determined by considering the balance\nof injected and dissipated power. This provides a prediction whose excellent\nquality is demonstrated by a data collapse for an extensive set of event-driven\nmolecular dynamics simulations where we varied the system size, particle\nnumber, the energy dissipated upon rupturing capillary bridges, and the bridge\nlength where rupture occurs. The three parameters of the theoretical prediction\nall lie within narrow margins of theoretical estimates."
    },
    {
        "anchor": "Molecular simulation of hierarchical structures in bent-core nematics: The structure of nematic liquid crystals formed by bent-core mesogens (BCMs)\nis studied in the context of Monte Carlo simulations of a simple molecular\nmodel that captures the symmetry, shape and flexibility of achiral BCMs. The\nresults indicate the formation of (i) clusters exhibiting local smectic order,\northogonal or tilted, with strong in-layer polar correlations and\nanti-ferroelectric juxtaposition of successive layers and (ii) large homochiral\ndomains through the helical arrangement of the tilted smectic clusters, whilst\nthe orthogonal clusters produce achiral (untwisted) nematic states.",
        "positive": "Isotropic-Nematic Transition in Liquid-Crystalline Elastomers: In liquid-crystalline elastomers, the nematic order parameter and the induced\nstrain vary smoothly across the isotropic-nematic transition, without the\nexpected first-order discontinuity. To investigate this smooth variation, we\nmeasure the strain as a function of temperature over a range of applied stress,\nfor elastomers crosslinked in the nematic and isotropic phases, and analyze the\nresults using a variation on Landau theory. This analysis shows that the smooth\nvariation arises from quenched disorder in the elastomer, combined with the\neffects of applied stress and internal stress."
    },
    {
        "anchor": "Active sieving across driven nanopores for tunable selectivity: Molecular separation traditionnally relies on sieving processes across\npassive nanoporous membranes. Here we explore theoretically the concept of\nnon-equilibrium active sieving. We investigate a simple model for an active\nnoisy nanopore, where gating - in terms of size or charge - is externally\ndriven at a tunable frequency. Our analytical and numerical results unveil a\nrich sieving diagram in terms of the forced gating frequency. Unexpectedly, the\nseparation ability is strongly increased as compared to its passive (zero\nfrequency) counterpart. It points also to the possibility of tuning dynamically\nthe osmotic pressure. Active separation outperforms passive sieving and\nrepresents a promising avenue for advanced filtration.",
        "positive": "Actuation performances of anisotropic gels: We investigated the actuation performances of anisotropic gels driven by\nmechanical and chemical stimuli, in terms of both deformation processes and\nstroke--curves, and distinguished between the fast response of gels before\ndiffusion starts and the asymptotic response attained at the steady state. We\nalso showed as the range of forces that an anisotropic hydrogel can exert when\nconstrained is especially wide;indeed, changing fiber orientation allows to\ninduce shear as well as transversely isotropic extensions."
    },
    {
        "anchor": "Rheological hysteresis in soft glassy materials: The nonlinear rheology of a soft glassy material is captured by its\nconstitutive relation, shear stress vs shear rate, which is most generally\nobtained by sweeping up or down the shear rate over a finite temporal window.\nFor a huge amount of complex fluids, the up and down sweeps do not superimpose\nand define a rheological hysteresis loop. By means of extensive rheometry\ncoupled to time-resolved velocimetry, we unravel the local scenario involved in\nrheological hysteresis for various types of well-studied soft materials. We\nintroduce two observables that quantify the hysteresis in macroscopic rheology\nand local velocimetry respectively, as a function of the sweep rate \\delta\nt^{-1}. Strikingly, both observables present a robust maximum with \\delta t,\nwhich defines a single material-dependent timescale that grows continuously\nfrom vanishingly small values in simple yield stress fluids to large values for\nstrongly time-dependent materials. In line with recent theoretical arguments,\nthese experimental results hint at a universal timescale-based framework for\nsoft glassy materials, where inhomogeneous flows characterized by shear bands\nand/or pluglike flow play a central role.",
        "positive": "Contact rolling and deformation in granular media: The paper considers rotations at different scales in granular materials: the\nrotations of individual particles, the rolling and rigid-rotation of particle\npairs, the rotational interactions of a particle within its cluster of\nneighbors, and the rotation of material regions. Numerical, Discrete Element\nMethod (DEM) simulations on two- and three-dimensional (2D and 3D) assemblies\nshow that particle rotations are diverse, that they increase with strain until\nthe material begins to soften, and that they are expressed in spatial patterns,\neven at small strains. The interactions of a pair of particles are a\ncombination of three modes: a contact deformation mode, a contact rolling mode,\nand a mode of rigid pair motions. Definitions are presented for each mode,\nincluding four different definitions of contact rolling. A rolling curl is also\ndefined, which describes the cumulative rolling of neighboring particles around\na central particle or sub-region. At a larger scale, material deformation and\nrotation are measured within small sub-regions of material, and the material\ndeformation can be attributed to separate contributions of contact rolling,\ncontact deformation, and the rigid-rotation of particle pairs. The diversity\nand extend of contact rolling were measured in 2D and 3D simulations. A\ndominant rolling pattern was observed, which resembles the interactions of\nrolling gears. This pattern can extend to distances of at least six particle\ndiameters from a central particle."
    },
    {
        "anchor": "Falsity of the Rouse Mode Solution of the Rouse and Zimm Models: The Rouse (J. Chem. Phys. 21, 1272 (1953)) and Zimm (J. Chem. Phys. 24}, 269\n(1956)) treatments of the dynamics of a polymer chain are shown to contain a\nfundamental mathematical error, which causes them to lose the\nzero-relaxation-rate, whole-body rotation motions dominant in viscosity and\ndielectric relaxation. As a result, the oft-cited mode solutions for these\nmodels are qualitatively incorrect. Comparison with the Wilson-Decius-Cross\ntreatment of vibrational modes of polyatomic molecules reveals qualitatively\nthe correct form for the solutions to the Rouse model.",
        "positive": "Phase behavior and morphology of multicomponent liquid mixtures: Multicomponent systems are ubiquitous in nature and industry. While the\nphysics of few-component liquid mixtures (i.e., binary and ternary ones) is\nwell-understood and routinely taught in undergraduate courses, the\nthermodynamic and kinetic properties of $N$-component mixtures with $N>3$ have\nremained relatively unexplored. An example of such a mixture is provided by the\nintracellular fluid, in which protein-rich droplets phase separate into\ndistinct membraneless organelles. In this work, we investigate equilibrium\nphase behavior and morphology of $N$-component liquid mixtures within the\nFlory-Huggins theory of regular solutions. In order to determine the number of\ncoexisting phases and their compositions, we developed a new algorithm for\nconstructing complete phase diagrams, based on numerical convexification of the\ndiscretized free energy landscape. Together with a Cahn-Hilliard approach for\nkinetics, we employ this method to study mixtures with $N=4$ and $5$\ncomponents. We report on both the coarsening behavior of such systems, as well\nas the resulting morphologies in three spatial dimensions. We discuss how the\nnumber of coexisting phases and their compositions can be extracted with\nPrincipal Component Analysis (PCA) and K-Means clustering algorithms. Finally,\nwe discuss how one can reverse engineer the interaction parameters and volume\nfractions of components in order to achieve a range of desired packing\nstructures, such as nested `Russian dolls' and encapsulated Janus droplets."
    },
    {
        "anchor": "Model studies on motion of respiratory droplets driven through a face\n  mask: Face masks are used to intercept respiratory droplets to prevent spreading of\nair-borne diseases. Designing face masks with better efficiency needs\nmicroscopic understanding on how respiratory droplets move through a mask. Here\nwe study a simple model on the interception of droplets by a face mask. The\nmask is treated as a polymeric network in an asymmetric confinement, while the\ndroplet is taken as a micrometer sized tracer colloidal particle, subject to\ndriving force that mimics the breathing. We study numerically, using the\nLangevin dynamics, the tracer particle permeation through the polymeric\nnetwork. We show that the permeation is an activated process following an\nArrhenius dependence on temperature. The potential energy profile responsible\nfor the activation process increases with tracer size, tracer bead interaction,\nnetwork rigidity and decreases with the driving force and confinement length. A\ndeeper energy barrier led to better efficiency to intercept the tracer\nparticles of a given size in the presence of driving force at room temperature.\nOur studies may help to design mask with better efficiency.",
        "positive": "Where is liquid-vapor interface located in solutions?: Two-component liquid-vapor systems are modeled as two bulk phases divided by\na two-dimensional surface phase and the mass and momentum balances are\ntheoretically studied. Comparing the derived equations with some typical models\nof surface rheology, useful information about the interface location is\nobtained. It is demonstrated that the surface phase, set on the surface of\ntension, coincides with the equimolecular interface for insoluble surfactants,\nwhereas it is placed on the surface of zero total mass density excess for\nsoluble ones. The applicability of the model to surface electrostatics is also\ndiscussed by introduction of a two-dimensional Maxwell equation for the surface\nphase."
    },
    {
        "anchor": "Strain-controlled critical slowing down in the rheology of disordered\n  networks: Networks and dense suspensions frequently reside near a boundary between soft\n(or fluid-like) and rigid (or solid-like) regimes. Transitions between these\nregimes can be driven by changes in structure, density, or applied stress or\nstrain. In general, near the onset or loss of rigidity in these systems,\ndissipation-limiting heterogeneous nonaffine rearrangements dominate the\nmacroscopic viscoelastic response, giving rise to diverging relaxation times\nand power-law rheology. Here, we describe a simple quantitative relationship\nbetween nonaffinity and the excess viscosity. We test this\nnonaffinity-viscosity relationship computationally and demonstrate its\nrheological consequences in simulations of strained filament networks and dense\nsuspensions. We also predict critical signatures in the rheology of\nsemiflexible and stiff biopolymer networks near the strain stiffening\ntransition.",
        "positive": "Ion Pair Free Energy Surface as a Probe of Ionic Liquid Structure: The numerous combinations of cations and anions turn out possible to produce\nionic liquids with fine-tuned properties once the correlation with the\nmolecular structure is known. In this sense, computer simulations are useful\ntools to explain and even to predict properties of ionic liquids. However,\nquantum mechanical methods are usually restricted to either small clusters or\nshort timescales, so that the use of parametrized force fields is needed for\nstudying the bulk liquids. A method is proposed in this work to enable a\ncomparison between quantum mechanical and both polarizable and non-polarizable\nforce fields by means of the calculation of free energy surfaces for the\ntranslational motion of the anion around the cation in gas phase. This method\nwas tested for imidazolium-based cations with 3 different anions, [BF4]-,\n[N(CN)2]-, and [NTf2]-. It was found better agreement with the DFT calculations\nwhen polarizability is introduced in the forcefield. In addition, the ion pair\nfree energy surfaces reproduced the main structural patterns observed in the\nfirst coordination shell in molecular dynamics simulations of the bulk liquid,\nproving to be useful probes for the liquid phase structure that can be computed\nwith higher level methods and the comparison with forcefields can indicate\nfurther improvements in their parametrization."
    },
    {
        "anchor": "Violation of triboelectric charge conservation on colliding particles: In microgravity experiments, we quantified the net charge on systems of two\nidentical, 434 \\textmu m diameter glass spheres before and after a collision.\nWe find that charge conservation is significantly violated. Independent of the\nsign of the total charge, the systems regularly lose some of their net charges,\nthat is, they slightly discharge. This implies that positive as well as\nnegative charge carriers become entrained into the surrounding atmosphere\nduring a collision.",
        "positive": "Dynamical density functional theory for the evaporation of droplets of\n  nanoparticle suspension: We develop a lattice gas model for the drying of droplets of a nanoparticle\nsuspension on a planar surface, using dynamical density functional theory\n(DDFT) to describe the time evolution of the solvent and nanoparticle density\nprofiles. The DDFT assumes a diffusive dynamics but does not include the\nadvective hydrodynamics of the solvent, so the model is relevant to highly\nviscous or near to equilibrium systems. Nonetheless, we see an equivalent of\nthe coffee-ring stain effect, but in the present model it occurs for\nthermodynamic rather the fluid-mechanical reasons. The model incorporates the\neffect of phase separation and vertical density variations within the droplet\nand the consequence of these on the nanoparticle deposition pattern on the\nsurface. We show how to include the effect of slip or no-slip at the surface\nand how this is related to the receding contact angle. We also determine how\nthe equilibrium contact angle depends on the microscopic interaction\nparameters."
    },
    {
        "anchor": "Binder migration during drying of lithium-ion battery electrodes:\n  modelling and comparison to experiment: The drying process is a crucial step in electrode manufacture as it can\naffect the component distribution within the electrode. Phenomena such as\nbinder migration can have negative effects in the form of poor cell performance\n(e.g. capacity fade) or mechanical failure (e.g. electrode delamination from\nthe current collector). We present a mathematical model that tracks the\nevolution of the binder concentration in the electrode during drying. Solutions\nto the model predict that low drying rates lead to a favourable homogeneous\nbinder profile across the electrode film, whereas high drying rates result in\nan unfavourable accumulation of binder near the evaporation surface. These\nresults show strong qualitative agreement with experimental observations and\nprovide a cogent explanation for why fast drying conditions result in poorly\nperforming electrodes. Finally, we provide some guidelines on how the drying\nprocess could be optimised to offer relatively short drying times whilst\nsimultaneously maintaining a roughly homogeneous binder distribution.",
        "positive": "Tautomeric Transitions in DNA: We study the tautomeric transitions in base pairs of DNA considering elastic\nproperties of DNA as classical and tunneling of protons as quantum, and show\nthat the dynamics of the transitions admits of soliton like solutions whose\nshape and size strongly depend on the structure of the double helix. In\nparticular, we have found that the set of discrete breathers can be drastically\nmodified by the interplay of the torsional and elastic constants. Our results\nmay have a bearing upon substitution mutagenesis within the framework of\nWatson-Crick's approach, and in this respect the breather soliton could\ndescribe conformations corresponding to point mutations. The numerical\nsimulation of soliton dynamics suggests that an initial distribution of base\npairs with low probability of mutation per pair but of a sufficiently large\nnumber of base pairs involved, could move and gather around a site so as to\nform a set of base pairs with high probability of mutation, for a period of\ntime approximately 1 musec. We suggest that the irradiation of DNA at\nfrequencies of the proton tunneling, that is in infra-red region, could cause\nmutations."
    },
    {
        "anchor": "Direct Measurement of the Free Energy of Aging Hard-Sphere Colloidal\n  Glasses: The nature of the glass transition is one of the most important unsolved\nproblems in condensed matter physics. The difference between glasses and\nliquids is believed to be caused by very large free energy barriers for\nparticle rearrangements; however so far it has not been possible to confirm\nthis experimentally. We provide the first quantitative determination of the\nfree energy for an aging hard-sphere colloidal glass. The determination of the\nfree energy allows for a number of new insights in the glass transition,\nnotably the quantification of the strong spatial and temporal heterogeneity in\nthe free energy. A study of the local minima of the free energy reveals that\nthe observed variations are directly related to the rearrangements of the\nparticles. Our main finding is that the probability of particle rearrangements\nshows a power law dependence on the free energy changes associated with the\nrearrangements, similarly to the Gutenberg-Richter law in seismology.",
        "positive": "Strengthening of a Polymer Interface: Interdiffusion and Crosslinking: In many industrial processes, pieces of the same polymer material are brought\ninto contact at a temperature above the glass transition. Interdiffusion then\ntakes place across the interface and leads to a strengthening of the junction.\nOften, a crosslinker agent is also added in order to improve the global\nmechanical properties of the material, as in the formation of latex films from\ndispersed solutions of polymer particles. In these systems, the interdiffusion\nprocess and the crosslinking reaction couple strongly, and, in practice, may\nsometimes interfere in a way that proves unfavorable to the tenacity of the\nfilm. We studied theoretically the competition between interdiffusion and\ncrosslinking, and found a control parameter tuning the balance between these\ntwo processes, in terms of simple physical quantities. The case of practical\ninterest occurs when this parameter is much smaller than unity: the reaction\nlocks the interfacial chains once a significant mixing has developed, resulting\nin films with good mechanical properties."
    },
    {
        "anchor": "Excitation of vibrational soft modes in disordered systems using active\n  oscillation: We propose a new method to characterize the spatial distribution of\nparticles' vibrations in solids with much lower computational costs compared to\nthe usual normal mode analysis. We excite the specific vibrational mode in a\ntwo dimensional athermal jammed system by giving a small amplitude of active\noscillation to each particle's size with an identical driving frequency. The\nresponse is then obtained as the real time displacements of the particles. We\nshow remarkable correlations between the real time displacements and the eigen\nvectors obtained from conventional normal mode analysis. More importantly, from\nthese real time displacements, we can measure the participation ratio and\nspatial polarization of particles' vibrations. From these measurements, we find\nthree distinct frequency regimes which characterize the spatial distribution\nand correlation of particles' vibrations in jammed amorphous solids.\nFurthermore, we can possibly apply this method to a much larger system to\nexamine the low frequency behaviour of amorphous solids with a much higher\nresolution of the frequency space.",
        "positive": "Hidden Asymptotic Symmetry in Long Elastic Beams on Softening\n  Foundations: Transverse wrinkles are known to appear in thin rectangular elastic sheets\nwhen stretched in the long direction. Numerically computed bifurcation diagrams\nfor extremely thin, highly stretched films indicate entire orbits of wrinkling\nsolutions, cf. Healey, et. al. [J. Nonlinear Sci., 23 (2013), pp.~777--805].\nThese correspond to arbitrary phase shifts of the wrinkled pattern in the\ntransverse direction. While such behavior is normally associated with problems\nin the presence of a continuous symmetry group, an unloaded rectangular sheet\npossesses only a finite symmetry group. In order to understand this phenomenon,\nwe consider a simpler problem more amenable to analysis -- a finite-length beam\non a nonlinear softening foundation under axial compression. We first obtain\nasymptotic results via amplitude equations, that are valid as a certain\nnon-dimensional beam length becomes sufficiently large. We deduce that any two\nphase-shifts of a solution differ from one another by exponentially small terms\nin that length. We validate this observation with numerical computations,\nindicating the presence of solution orbits for sufficiently long beams. We\nrefer to this as \"hidden asymptotic symmetry\"."
    },
    {
        "anchor": "Emergence of Multiscale Dynamics in Colloidal Gels: To gain insight into the kinetics of colloidal gel evolution at low particle\nvolume fractions $\\phi$, we utilize differential dynamic microscopy to\ninvestigate particle aggregation, geometric percolation, and the subsequent\ntransition to nonergodic dynamics. We report the emergence of unexpectedly rich\nmultiscale dynamics upon the onset of nonergodicity, which separates the wave\nvectors $q$ into three different regimes. In the high-$q$ domain, the gel\nexhibits $\\phi$-independent internal vibrations of fractal clusters. The\nintermediate-$q$ domain is dominated by density fluctuations at the length\nscale of the clusters, as evidenced by the $q$-independence of the relaxation\ntime $\\tau$. In the low-$q$ domain, the scaling of $\\tau$ as $q^{-3}$ suggests\nthat the network appears homogeneous. The transitions between these three\nregimes introduce two characteristic length scales, distinct from the cluster\nsize.",
        "positive": "Universal stress correlations in crystalline and amorphous packings: We present a universal characterization of stress correlations in athermal\nsystems, across crystalline to amorphous packings. Via numerical analysis of\nstatic configurations of particles interacting through harmonic as well as\nLennard-Jones potentials, for a variety of preparation protocols and ranges of\nmicroscopic disorder, we show that the properties of the stress correlations at\nlarge lengthscales are surprisingly universal across all situations,\nindependent of structural correlations, or the correlations in orientational\norder. In the near-crystalline limit, we present exact results for the stress\ncorrelations for both models, which work surprisingly well at large\nlengthscales, even in the amorphous phase. Finally, we study the differences in\nstress fluctuations across the amorphization transition, where stress\ncorrelations reveal the loss of periodicity in the structure at short\nlengthscales with increasing disorder."
    },
    {
        "anchor": "Numerical simulations of self-diffusiophoretic colloids at fluid\n  interfaces: The dynamics of active colloids is very sensitive to the presence of\nboundaries and interfaces which therefore can be used to control their motion.\nHere we analyze the dynamics of active colloids adsorbed at a fluid-fluid\ninterface. By using a mesoscopic numerical approach which relies on an\napproximated numerical solution of the Navier-Stokes equation, we show that\nwhen adsorbed at a fluid interface, an active colloid experiences a net torque\neven in the absence of a viscosity contrast between the two adjacent fluids. In\nparticular, we study the dependence of this torque on the contact angle of the\ncolloid with the fluid-fluid interface and on its surface properties. We\nrationalize our results via an approximate approach which accounts for the\nappearance of a local friction coefficient. By providing insight into the\ndynamics of active colloids adsorbed at fluid interfaces, our results are\nrelevant for two-dimensional self assembly and emulsion stabilization by means\nof active colloids.",
        "positive": "Brushes of flexible, semiflexible and rodlike diblock polyampholytes:\n  Molecular dynamics simulation and scaling analysis: Planar brushes of flexible, semiflexible and rodlike diblock polyampholytes\nare studied using molecular dynamics simulations and scaling analysis in a wide\nrange of the grafting density. Simulations show linear dependence of the\naverage thickness on the grafting density for all the brushes regardless of\ntheir different equilibrium conformations and different flexibility of anchored\nchains. Slopes of fitted lines to the average thickness of the brushes of\nsemiflexible and rodlike polyampholytes versus the grafting density are\napproximately the same and differ considerably from that of the brush of\nflexible chains. The average thickness of the brush of diblock polyampholytes\nis also obtained as a function of the grafting density using a simple scaling\nanalysis which is in good agreement with the results of our simulations."
    },
    {
        "anchor": "Effects of particle size-shape correlations on shear strength of\n  granular materials: The case of particle elongation: Granular materials often present correlations between particle size and shape\ndue to their geological formation and mechanisms of weathering and\nfragmentation. It is known that particle shape strongly affects shear strength.\nHowever, the effects of shape can be modified by the role the particle plays in\na sample given its size. We explore the steady shear strength of samples\ncomposed of particles presenting size-shape correlations and we focus on the\ncase of particle elongation in two opposite scenarios: (A) large elongated\ngrains with finer circular grains and (B) large circular grains with elongated\nfiner grains. By means of numerical simulations, we probe the shear strength of\nsamples of varying particle size span from mono to highly polydisperse and\nparticle aspect ratios varying between 1 and 5. We find that the two\ncorrelations tested strongly impact the shear strength as particle size span\nevolves. Microstructural analyses allow us to identify how each correlation\naffects connectivity and anisotropies linked to the orientation of the\nparticles and load transmission. Decompositions of the stress tensor let us\nidentify the sources of the different mechanical behavior in each correlation\nand determine the contributions of each particle shape to macroscopic shear\nstrength. This study proves that common small-scaling methods based on\ntruncated or parallel particle size distributions can incur in\nunder/over-estimations of shear strength if particle shapes are not considered\nin the scaling process.",
        "positive": "Simulations of ionic liquids confined by metal electrodes using periodic\n  Green functions: We present an efficient method for simulating Coulomb systems confined by\nmetal electrodes. The approach relies on Green functions techniques to obtain\nthe electrostatic potential for an infinite periodically replicated system.\nThis avoids the use of image charges or an explicit calculation of the induced\nsurface charge, both of which dramatically slows down the simulations. To\ndemonstrate the utility of the new method we use it to obtain the ionic density\nprofiles and the differential capacitances, which are of great practical and\nheoretical interest, for a lattice model of an ionic liquid."
    },
    {
        "anchor": "Building micro-soccer-balls with evaporating colloidal fakir drops: Evaporation-driven particle self-assembly can be used to generate\nthree-dimensional microstructures. We present a new method to create these\ncolloidal microstructures, in which we can control the amount of particles and\ntheir packing fraction. To this end, we evaporate colloidal dispersion droplets\non a special type of superhydrophobic micro-structured surface, on which the\ndroplet re- mains in Cassie-Baxter state during the entire evaporative process.\nThe remainders of the droplet consist of a massive spherical cluster of the\nmicrospheres, with diameters ranging from a few tens up to several hundreds of\nmicrons. We present scaling arguments to show how the final particle packing\nfraction of these balls depends on the dynamics of the droplet evaporation.",
        "positive": "MFCPji & MFIDji: New ImageJ Macros To Analyze Structure Formed In\n  Magnetic Nanofluid: The aqueous magnetic nanofluid consists of superparamagnetic nanoparticles,\nwith a typical size 10-12 nm. On the application of the magnetic field, these\nnanoparticles align heterogeneously and form a chain or chain-like structure.\nThis structure is observed using a microscope. Although such chain or\nmicrostructure formation is well reported in many articles, the method to\nidentify and determine chain parameters, e.g., chain length, width, and\nassociated counts, are scare. Similarly, inter-chain or successive distance is\none of the critical parameters for the development of magnetic nanofluid based\ndevices. This paper describes Magnetic Field induced Chain Parameters (MFCP)\nand Magnetic Field induced Interchain Distance (MFID) a set of new ImageJ\nmethods to identify and determine (i) chain length, width, and associated\ncounts, along with (ii) successive distance of the chains respectively in the\nmagnetic nanofluid. This utilises a macro files such as MFCPji.txt and\nMFIDji.txt for ImageJ, which can be used on microscopic image of magnetic\nnanofluid without and with application of magnetic field. The method requires\nno specialised scientific equipment and can be run entirely using free to\ndownload software. The examples of microstructure formations in two different\nmagnetic fluids (A & B) are discussed. The results of the associated weighted\naverage chain width and counts, as well as the successive distance between the\nchains, are reported. The chain parameters are useful to determine diffraction\ngrating angle. The MFCPji and MFIDji macros has been integrated into a macro\ntool set that can be configured to be run on ImageJ start up. The MFCPji and\nMFIDji are available from the following Uniform Resource Locator (URLs):\nhttps://github.com/urveshsoni/ImageJ -- Macros\nhttps://ruchadesailab.wordpress.com/publication/"
    },
    {
        "anchor": "Self-motility of an active particle induced by correlations in the\n  surrounding solution: Current models of phoretic transport rely on molecular forces creating a\n\"diffuse\" particle-fluid interface. We investigate theoretically an alternative\nmechanism, in which a diffuse interface emerges solely due to a non-vanishing\ncorrelation length of the surrounding solution. This mechanism can drive\nself-motility of a chemically active particle. Numerical estimates indicate\nthat the velocity can reach micrometers per second. The predicted phenomenology\nincludes a bilinear dependence of the velocity on the activity and a possible\ndouble velocity reversal upon varying the correlation length.",
        "positive": "Acceleration of DNA Replication of Klenow Fragment by Small Resisting\n  Force: DNA polymerases are an essential class of enzymes or molecular motors that\ncatalyze processive DNA syntheses during DNA replications. A critical issue for\nDNA polymerases is their molecular mechanism of processive DNA replication. We\nhave previously proposed a model for chemomechanical coupling of DNA\npolymerases, based on which the predicted results have been provided about the\ndependence of DNA replication velocity upon the external force on Klenow\nfragment of DNA polymerase I. Here, we performed single molecule measurements\nof the replication velocity of Klenow fragment under the external force by\nusing magnetic tweezers. The single molecule data verified quantitatively the\nprevious theoretical predictions, which is critical to the chemomechanical\ncoupling mechanism of DNA polymerases. A prominent characteristic for the\nKlenow fragment is that the replication velocity is independent of the\nassisting force whereas the velocity increases largely with the increase of the\nresisting force, attains the maximum velocity at about 3.8 pN and then\ndecreases with the further increase of the resisting force."
    },
    {
        "anchor": "A Theory of Shape-Shifting Droplets: Recent studies of cooled oil emulsion droplets uncovered transformations into\na host of flattened shapes with straight edges and sharp corners, driven by a\npartial phase transition of the bulk liquid phase. Here, we explore\ntheoretically the simplest geometric competition between this phase transition\nand surface tension in planar polygons, and recover the observed sequence of\nshapes and their statistics in qualitative agreement with experiments.\nExtending the model to capture some of the three-dimensional structure of the\ndroplets, we analyze the evolution of protrusions sprouting from the vertices\nof the platelets and the topological transition of a puncturing planar polygon.",
        "positive": "Stretching DNA in hard-wall potential channels: A three dimensional mesoscopic model is applied to study the properties of\nshort DNA chains in a confining environment. The cylindrical channel is\nrepresented by a hard-wall repulsive potential incorporated in the system\nHamiltonian. The macroscopic helical parameters are computed performing\nstatistical averages over the ensemble of microscopic base pair fluctuations.\nThe average molecule elongation, measured by the end-to-end distance, is\nderived as a function of the channel potential parameters both for a\nhomogeneous and a heterogeneous chain. The overall results suggest that the\nmesoscopic model, with the channel potential term, yields consistent\nquantitative estimates for the stretching and twisting of short chains."
    },
    {
        "anchor": "Modelling persistence of motion in a crowded environment: the diffusive\n  limit of excluding velocity-jump processes: Persistence of motion is the tendency of an object to maintain motion in a\ndirection for short time scales without necessarily being biased in any\ndirection in the long term. One of the most appropriate mathematical tools to\nstudy this behaviour is an agent-based velocity-jump process. In the absence of\nagent-agent interaction, the mean-field continuum limit of the agent-based\nmodel (ABM) gives rise to the well known hyperbolic telegraph equation. When\nagent-agent interaction is included in the ABM, a strictly advective system of\npartial differential equations (PDEs) can be derived at the population-level.\nHowever, no diffusive limit of the ABM has been obtained from such a model.\nConnecting the microscopic behaviour of the ABM to a diffusive macroscopic\ndescription is desirable, since it allows the exploration of a wider range of\nscenarios and establishes a direct connection with commonly used statistical\ntools of movement analysis. In order to connect the ABM at the population-level\nto a diffusive PDE at the population-level, we consider a generalisation of the\nagent-based velocity-jump process on a two-dimensional lattice with three forms\nof agent interaction. This generalisation allows us to take a diffusive limit\nand obtain a faithful population-level description. We investigate the\nproperties of the model at both the individual and population-level and we\nelucidate some of the models' key characteristic features. In particular, we\nshow an intrinsic anisotropy inherent to the models and we find evidence of a\nspontaneous form of aggregation at both the micro- and macro-scales.",
        "positive": "Correlations of Structure and Dynamics in an Aging Colloidal Glass: We study concentrated colloidal suspensions, a model system which has a glass\ntransition. Samples in the glassy state show aging, in that the motion of the\ncolloidal particles slows as the sample ages from an initial state. We study\nthe relationship between the static structure and the slowing dynamics, using\nconfocal microscopy to follow the three-dimensional motion of the particles.\nThe structure is quantified by considering tetrahedra formed by quadruplets of\nneighboring particles. We find that while the sample clearly slows down during\naging, the static properties as measured by tetrahedral quantities do not vary.\nHowever, a weak correlation between tetrahedron shape and mobility is observed,\nsuggesting that the structure facilitates the motion responsible for the sample\naging."
    },
    {
        "anchor": "Diffusion dynamics of an overdamped active ellipsoidal particle in two\n  dimensions: Shape asymmetry is the most abundant in nature and attracted great interest\nin recent research. The phenomenon is widely recognized: a free ellipsoidal\nBrownian particle displays anisotropic diffusion during short time intervals,\nwhich subsequently transitions to an isotropic diffusion pattern over longer\ntime scales. We have further expanded this concept to incorporate active\nellipsoidal particles characterized by an initial self-propelled velocity. In\nour previous study\\cite{ghosh2022persistence}, we derived the analytical\nexpressions and simulation results of the persistence probability of an active\nanisotropic particle without any external potential and with an external\nharmonic potential. This paper provides analytical and simulation results of\ndiffusion coefficients of an active ellipsoidal particle. In comparison to a\npassive particle, we demonstrate that the long-term diffusion coefficient of an\nactive particle is influenced by both the magnitude of the propulsion velocity\nand the rotational diffusion coefficient. We have also studied the\napproximations of different results for diffusion coefficients in $t\\ll\nD_\\theta^{-1}$ time-scale. We investigated diffusion dynamics for the free\nparticle as well as the particle in a harmonic trap, and the particle subject\nto a constant field force. Additionally, we have studied the scaled average\nvelocity of an ellipsoidal active particle in different force fields. We show\nanalytically and numerically that the long-term diffusion coefficient is\naltered by the presence of external forces in comparison to a free particle.",
        "positive": "Three-dimensional soliton-like distortions in flexoelectric nematic\n  liquid crystals: modeling and linear analysis: This article models experimentally observed three dimensional particle-like\nwaves that develop in nematic liquid crystals, with negative dielectric and\nconductive anisotropy, when subject to an applied alternating electric field.\nThe liquid crystal is confined in a thin region between two plates,\nperpendicular to the applied field. The horizontal, uniformly aligned director\nfield is at equilibrium due to the negative anisotropy of the media. However,\nsuch a state is unstable to perturbations that manifest themselves as confined,\nbullet-like, director distortions traveling up and down the sample at a speed\nof several hundred microns per second. It is experimentally predicted that\nflexoelectricity plays a key role in generating the soliton-like behavior. We\ndevelop a variational model that accounts for ansiostropic dielectric,\nconductive, flexolectric, elastic and viscous forces. We perform a stability\nanalysis of the uniformly aligned equilibrium state to determine the threshold\nwave numbers, size, phase-shift and speed of the soliton-like disturbance. We\nshow that the model predictions are in very good agreement with the\nexperimentally measured values. The work models and analyzes a\nthree-dimensional soliton-like instability reported, for the first time in\nflexoelectric liquid crystals, pointing towards a potential application as a\nnew type of nanotransport device."
    },
    {
        "anchor": "Low frequency Rabi spectroscopy of dissipative two level systems. The\n  dressed state approach: We have analyzed a dissipative two level quantum system (TLS) which is\ncontinuously and simultaneously irradiated by a high and low frequency\nexcitation. The interaction of the TLS with a high frequency excitation is\nconsidered in the frame of the dressed state approach. A linear response of the\ncoupled TLS and corresponding photon field system to a signal whose frequency\nis of the order of the Rabi frequency is found. The response exhibits undamped\nlow frequency oscillations, whose amplitude has a clear resonance at the Rabi\nfrequency with the width being dependent on the damping rates of the TLS. The\nmethod can be useful for low-frequency Rabi spectroscopy in various physical\nsystems described by a two-level Hamiltonian, such as nuclei spins in NMR,\ndouble well quantum dots, superconducting flux and charge qubits, etc. The\napplication of the method to a superconducting flux qubit and to the detection\nof NMR is considered in detail.",
        "positive": "Sensitivity of Granular Force Chain Orientation to Disorder-induced\n  Metastable Relaxation: A two-dimensional system of photoelastic disks subject to vertical tapping\nagainst gravity was experimentally monitored from ordered to disordered\nconfigurations by varying bidispersity. The packing fraction $\\phi$,\ncoordination number $Z$, and an appropriately defined force chain orientational\norder parameter $S$, all exhibit similar sharp transition with small increase\nin disorder. A measurable change in $S$, but not $\\phi~\\&~Z$, was detected\nunder tapping. We find disorder-induced metastability does not show\nconfigurational relaxation, but can be detected via force chain reorientations."
    },
    {
        "anchor": "Dynamic jamming of dense suspensions under tilted impact: Dense particulate suspensions can not only increase their viscosity and shear\nthicken under external forcing, but also jam into a solid-like state that is\nfully reversible when the force is removed. An impact on the surface of a dense\nsuspension can trigger this jamming process by generating a shear front that\npropagates into the bulk of the system. Tracking and visualizing such a front\nis difficult because suspensions are optically opaque and the front can\npropagate as fast as several meters per second. Recently, high-speed ultrasound\nimaging has been used to overcome this problem and extract two-dimensional\nsections of the flow field associated with jamming front propagation. Here we\nextend this method to reconstruct the three-dimensional flow field. This\nenables us to investigate the evolution of jamming fronts for which axisymmetry\ncannot be assumed, such as impact at angles tilted away from the normal to the\nfree surface of the suspension. We find that sufficiently far from solid\nboundaries the resulting flow field is approximately identical to that\ngenerated by normal impact, but rotated and aligned with the angle of impact.\nHowever, once the front approaches the solid boundary at the bottom of the\ncontainer, it generates a squeeze flow that deforms the front profile and\ncauses jamming to proceed in a non-axisymmetric manner.",
        "positive": "Cyclic thermo-mechanical performance of granular beds: Effect of\n  elastoplasticity: Understanding the coupled thermo-mechanical behaviour of compacted granular\nbeds can benefit various industrial applications, such as pebble bed design in\nfusion reactors. In this study, a thermo-mechanical discrete element method\nbased on our previous work is improved and adapted to investigate the cyclic\nthermo-mechanical performance of gas-filled granular materials composed of\nelastoplastic grains. An interparticle contact model is developed considering\nthe plastic deformation of grains. Through the simulation on a representative\nvolume element of beryllium pebble beds, we provide grain-scale insight into\nthe evolution of thermal conductivity and stress. The simulation results\nsuggest that the network of thermal contacts is impeded by plastic deformation\nleading to a significant drop of thermal conductivity during cooling. This\neffect can be suppressed by increasing the initial packing factor. Not limited\nto pebble bed design, the conclusion of this work can also pave the way for\noptimizing powder-based manufacturing and energy storage, where combined\nthermo-mechanical loading conditions and elastoplastic deformation of\nindividual particles are involved."
    },
    {
        "anchor": "Explaining the low-frequency shear elasticity of confined liquids: Experimental observations of unexpected shear rigidity in confined liquids,\non very low frequency scales on the order of 0.01-0.1 Hz, call into question\nour basic understanding of the elasticity of liquids and have posed a challenge\nto theoretical models of the liquid state ever since. Here we combine the\nnonaffine theory of lattice dynamics valid for disordered condensed matter\nsystems with the Frenkel theory of the liquid state. The emerging framework\nshows that applying confinement to a liquid can effectively suppress the low\nfrequency modes that are responsible for nonaffine soft mechanical response,\nthus leading to an effective increase of the liquid shear rigidity. The new\ntheory successfully predicts the scaling law $G'\\sim L^{-3}$ for the\nlow-frequency shear modulus of liquids as a function of the confinement length\n$L$, in agreement with experimental results, and provides the basis for a more\ngeneral description of the elasticity of liquids across different time and\nlength scales.",
        "positive": "BioVEC: A program for Biomolecule Visualization with Ellipsoidal\n  Coarse-graining: Biomolecule Visualization with Ellipsoidal Coarse-graining (BioVEC) is a tool\nfor visualizing molecular dynamics simulation data while allowing\ncoarse-grained residues to be rendered as ellipsoids. BioVEC reads in\nconfiguration files, which may be output from molecular dynamics simulations\nthat include orientation output in either quaternion or ANISOU format, and can\nrender frames of the trajectory in several common image formats for subsequent\nconcatenation into a movie file. The BioVEC program is written in C++, uses the\nOpenGL API for rendering, and is open source. It is lightweight, allows for\nuser-defined settings for and texture, and runs on either Windows or Linux\nplatforms."
    },
    {
        "anchor": "Plasticity and Aging of Folded Elastic Sheets: We investigate the dissipative mechanisms exhibited by creased material\nsheets when subjected to mechanical loading, which comes in the form of\nplasticity and relaxation phenomena within the creases. After demonstrating\nthat plasticity mostly affects the rest angle of the creases, we devise a\nmapping between this quantity and the macroscopic state of the system that\nallows us to track its reference configuration along an arbitrary loading path,\nresulting in a powerful monitoring and design tool for crease-based\nmetamaterials. Furthermore, we show that complex relaxation phenomena, in\nparticular memory effects, can give rise to a non-monotonic response at the\ncrease level, possibly relating to the similar behavior reported for crumpled\nsheets. We describe our observations through a classical double-logarithmic\ntime evolution and obtain a constitutive behavior compatible with that of the\nunderlying material. Thus the lever effect provided by the crease allows\nmagnified access to the material's rheology.",
        "positive": "Is the Structural Relaxation of Glasses Controlled by Equilibrium Shear\n  Viscosity?: Knowledge of relaxation processes is fundamental in glass science and\ntechnology because relaxation is intrinsically related to vitrification,\ntempering as well as to annealing and sev-eral applications of glasses.\nHowever, there are conflicting reports -- summarized here for different glasses\n-- on whether the structural relaxation time of glass can be calculated using\nthe Maxwell equation, which relates relaxation time with shear viscosity and\nshear modulus. Hence, this study aimed to verify whether these two relaxation\ntimes are comparable. The structural relaxation kinetics of a lead metasilicate\nglass were studied by measuring the re-fractive index variation over time at\ntemperatures between 5 and 25 K below the fictive temperature, which was\ninitially set 5 K below the glass transition temperature. Equilibrium shear\nviscosity was measured above and below the glass transition range, expanding\nthe current knowledge by one order of magnitude. The Kohlrausch equation\ndescribed very well the experimental structural relaxation kinetics throughout\nthe investigated temperature range and the Kohlrausch exponent increased with\ntemperature, in agreement with studies on other glasses. The experimental\naverage structural relaxation times were much longer than the values computed\nfrom isostructural viscosity, as expected. Still, they were less than one order\nof magnitude higher than the average relaxation time computed through the\nMaxwell equation, which relies on equilibrium shear viscosity. Thus, these\nresults demon-strate that the structural relaxation process is not controlled\nby isostructural viscosity, and that equilibrium shear viscosity only provides\na lower boundary for structural relaxation kinetics."
    },
    {
        "anchor": "Half or full core-hole in density functional theory X-ray absorption\n  spectrum calculations of water?: We analyze the performance of two different core-hole potentials in the\ntheoretical modeling of XAS of ice, liquid and gas phase water; the use of a\nfull core-hole (FCH) in the calculations, as suggested by Hetenyi et al. [J.\nChem. Phys. 120 (18), 8632 (2004)], gives poor agreement with experiment in\nterms of intensity distribution as well as transition energies, while the half\ncore hole (HCH) potential, in the case of water, provides a better compromise\nbetween initial and final state effects, leading to good agreement with the\nexperimental data.",
        "positive": "Dynamic Approach to the Fully Frustrated XY Model: Using Monte Carlo simulations, we systematically investigate the\nnon-equilibrium dynamics of the chiral degree of freedom in the two-dimensional\nfully frustrated XY model. The critical initial increase of the staggered\nchiral magnetization is observed. By means of the short-time dynamics approach,\nwe estimate the second order phase transition temperature $T_{c}$ and all the\ndynamic and static critical exponents $\\theta$, z, $\\beta$ and $\\nu$."
    },
    {
        "anchor": "Derivation of the phase field crystal model for colloidal solidification: The phase-field crystal model is by now widely used in order to predict\ncrystal nucleation and growth. For colloidal solidification with completely\noverdamped individual particle motion, we show that the phase-field crystal\ndynamics can be derived from the microscopic Smoluchowski equation via\ndynamical density functional theory. The different underlying approximations\nare discussed. In particular, a variant of the phase-field crystal model is\nproposed which involves less approximations than the standard phase-field\ncrystal model. We finally test the validity of these phase-field crystal models\nagainst dynamical density functional theory. In particular, the velocities of a\nlinear crystal front from the undercooled melt are compared as a function of\nthe undercooling for a two-dimensional colloidal suspension of parallel\ndipoles. Good agreement is only obtained by a drastic scaling of the free\nenergies in the phase-field crystal model in order to match the bulk freezing\ntransition point.",
        "positive": "Heterogeneous and anisotropic dynamics of a 2D gel: We report X-ray Photon Correlation Spectroscopy (XPCS) results on a\nbidimensional (2D) gel formed by a Langmuir monolayer of gold nanoparticles.\nThe system allows an experimental determination of the fourth order time\ncorrelation function which is compared to the usual second order correlation\nfunctions and to the mechanical response measured on macroscopic scale. The\nobserved dynamics is anisotropic, heterogeneous and super-diffusive on the\nnanoscale. Different time scales, associated with fast heterogeneous dynamics\ninside 2D cages and slower motion of larger parts of the film, can be\nidentified from the correlation functions."
    },
    {
        "anchor": "Down-hill creep of a granular material under expansion/contraction\n  cycles: We investigate the down-hill creep of a layer of granular material on a slope\ncaused by an oscillatory variation of the size of the particles. The material\nis modeled as an athermal two dimensional polydisperse system of soft disks\nunder the action of gravity. The slope angle is below the critical rest angle\nand therefore the system reaches an equilibrium configuration under static\nexternal conditions. However, under a protocol in which particles slowly change\nsize in a quasistatic oscillatory way the system is observed to creep down in a\nsynchronized way with the oscillation. We measure the creep advance per cycle\nas a function of the slope angle and the degree of change in particle size. In\naddition, we consider a situation in which the particle size oscillation\namplitude decreases with depth, as it may be argued to occur in the case of a\ngranular soil in an inclined terrain. In this case creep profiles that are\nmaximum at the surface and smoothly vanish with depth are obtained, as it is\nobserved to occur in the field.",
        "positive": "Confined Growth with slow surface kinetics: a Thin Film Model approach: Recent experimental and theoretical investigations of crystal growth from\nsolution in the vicinity of an impermeable wall have shown that: (i) growth can\nbe maintained within the contact region when a liquid film is present between\nthe crystal and the substrate; (ii) a cavity can form in the center of the\ncontact region due to insufficient supply of mass through the liquid film.\nHere, we investigate the influence of surface kinetics on these phenomena using\na thin film model. First, we determine the growth rate within the confined\nregion in the absence of a cavity. Growth within the contact induces a drift of\nthe crystal away from the substrate. Our results suggest novel strategies to\nmeasure surface kinetic coefficients based on the observation of this drift.\nFor the specific case where growth is controlled by surface kinetics outside\nthe contact, we show that the total displacement of the crystal due to the\ngrowth in the contact is finite. As a consequence, the growth shape approaches\nasymptotically the free growth shape truncated by a plane passing through the\ncenter of the crystal. Second, we investigate the conditions under which a\ncavity forms. The critical supersaturation above which the cavity forms is\nfound to be larger for slower surface kinetics. In addition, the critical\nsupersaturation decays as a power law of the contact size. The asymptotic value\nof the critical supersaturation and the exponent of the decay are found to be\ndifferent for attractive and repulsive disjoining pressures. Finally, our\nprevious representation of the transition within a morphology diagram appears\nto be uninformative in the limit of slow surface kinetics."
    },
    {
        "anchor": "Vapor-liquid coexistence of the Stockmayer fluid in nonuniform external\n  fields: We investigate the structure and phase behavior of the Stockmayer fluid in\nthe presence of nonuniform electric fields using molecular simulation. We find\nthat an initially homogeneous vapor phase undergoes a local phase separation in\na nonuniform field due to the combined effect of the field gradient and the\nfluid vapor--liquid equilibrium. This results in a high density fluid\ncondensing in the strong field region. The system polarization exhibits a\nstrong field dependence due to the fluid condensation.",
        "positive": "Effects of stretching on the frictional stress of rubber: In this paper, we report on new experimental results on the effects of\nin-plane surface stretching on the friction of Poly(DiMethylSiloxane) (PDMS)\nrubber with smooth rigid probes. Friction-induced displacement fields are\nmeasured at the surface of the PDMS substrate under steady-state sliding. Then,\nthe corresponding contact pressure and frictional stress distributions are\ndetermined from an inversion procedure. Using this approach, we show that the\nlocal frictional stress $\\tau$ is proportional to the local stretch ratio\n$\\lambda$ at the rubber surface. Additional data using a triangular flat punch\nindicate that $\\tau(\\lambda)$ relationship is independent on the contact\ngeometry. From friction experiments using pre-stretched PDMS substrate, it is\nalso found that the stretch-dependence of the frictional stress is isotropic,\ni.e. it does not depend on the angle between stretching and sliding directions.\nPotential physical explanations for this phenomenon are provided within the\nframework of Schallamach's friction model. Although the present experiments are\ndealing with smooth contact interfaces, the reported $\\tau(\\lambda)$ dependence\nis also relevant to the friction of statistically rough contact interfaces,\nwhile not accounted for in related contact mechanics models."
    },
    {
        "anchor": "Beyond standard Poisson-Boltzmann theory: ion-specific interactions in\n  aqueous solutions: The Poisson-Boltzmann mean-field description of ionic solutions has been\nsuccessfully used in predicting charge distributions and interactions between\ncharged macromolecules. While the electrostatic model of charged fluids, on\nwhich the Poisson-Boltzmann description rests, and its statistical mechanical\nconsequences have been scrutinized in great detail, much less is understood\nabout its probable shortcomings when dealing with various aspects of real\nphysical, chemical and biological systems. These shortcomings are not only a\nconsequence of the limitations of the mean-field approximation per se, but\nperhaps are primarily due to the fact that the purely Coulombic model\nHamiltonian does not take into account various additional interactions that are\nnot electrostatic in their origin. We explore several possible\nnon-electrostatic contributions to the free energy of ions in confined aqueous\nsolutions and investigate their ramifications and consequences on ionic\nprofiles and interactions between charged surfaces and macromolecules.",
        "positive": "Invariants in the Yukawa system's thermodynamic phase diagram: This paper shows that several known properties of the Yukawa system can be\nderived from the isomorph theory, which applies to any system that has strong\ncorrelations between its virial and potential-energy equilibrium fluctuations.\nSuch \"Roskilde-simple\" systems have a simplified thermodynamic phase diagram\nderiving from the fact that they have curves (isomorphs) along which structure\nand dynamics in reduced units are invariant to a good approximation. We show\nthat the Yukawa system has strong virial potential-energy correlations and\nidentify its isomorphs by two different methods. One method, the so-called\ndirect isomorph check, identifies isomorphs numerically from jumps of\nrelatively small density changes (here 10%). The second method identifies\nisomorphs analytically from the pair potential. The curves obtained by the two\nmethods are close to each other; these curves are confirmed to be isomorphs by\ndemonstrating the invariance of the radial distribution function, the static\nstructure factor, the mean-square displacement as a function of time, and the\nincoherent intermediate scattering function. Since the melting line is\npredicted to be an isomorph, the theory provides a derivation of a known\napproximate analytical expression for this line in the temperature-density\nphase diagram. The paper's results give the first demonstration that the\nisomorph theory can be applied to systems like dense colloidal suspensions and\nstrongly coupled dusty plasmas."
    },
    {
        "anchor": "Modelling nematohydrodynamics in liquid crystal devices: We formulate a lattice Boltzmann algorithm which solves the hydrodynamic\nequations of motion for nematic liquid crystals. The applicability of the\napproach is demonstrated by presenting results for two liquid crystal devices\nwhere flow has an important role to play in the switching.",
        "positive": "Water: one molecule, two surfaces, one mistake: In order to rigorously evaluate the energy and dipole moment of a certain\nconfiguration of molecules one needs to solve the Schr\\\"odinger equation.\nRepeating this for many different configurations allows one to determine the\npotential energy surface (PES) and the dipole moment surface (DMS). Since the\nearly days of computer simulation it has been implicitly accepted that for\nempirical potentials the charges used to fit the PES should also be used to\ndescribe the DMS. This is a mistake. Partial charges are not observable\nmagnitudes. They should be regarded as adjustable fitting parameters. Optimal\nvalues used to describe the PES are not necessarily the best to describe the\nDMS. One could use two fits: one for the PES, and another for the DMS. This is\na common practice in the quantum chemistry community, but not used so often by\nthe community performing computer simulations. This idea affects all types of\nmodelling of water (with the exception of ab-initio calculations) from coarse\ngrained to non-polarizable and polarizable models. We anticipate that an area\nthat will benefit dramatically from having both, a good PES and a good DMS, is\nthe modelling of water in the presence of electric fields."
    },
    {
        "anchor": "Phase behaviour of colloidal assemblies on 2D corrugated substrates: We investigate - with Monte Carlo computer simulations - the phase behaviour\nof dimeric colloidal molecules on periodic substrates with square symmetry. The\nmolecules are formed in a two-dimensional suspension of like charged colloids\nsubject to periodic external confinement, which can be experimentally realized\nby optical methods. We study the evolution of positional and orientational\norder by varying the temperature across the melting transition. We propose and\nevaluate appropriate order parameters as well as the specific heat capacity and\nshow that the decay of positional correlations belongs to a class of crossover\ntransitions while the orientational melting is a second-order phase transition.",
        "positive": "Entangled granular media: We study the geometrically induced cohesion of ensembles of granular\n\"u-particles\" which mechanically entangle through particle interpenetration. We\nvary the length-to-width ratio $l/w$ of the u-particles and form them into\nfree-standing vertical columns. In laboratory experiment we monitor the\nresponse of the columns to sinusoidal vibration (frequency $f$, peak\nacceleration $\\Gamma$). Column collapse occurs in a characteristic time,\n$\\tau$, which follows the relation $\\tau = f^{-1} \\exp(\\Delta / \\Gamma)$.\n$\\Delta$ resembles an activation energy and is maximal at intermediate $l/w$.\nSimulation reveals that optimal strength results from competition between\npacking and entanglement."
    },
    {
        "anchor": "Surface response of a polymer network: Semi-infinite network: We study theoretically the surface response of a semi-infinite viscoelastic\npolymer network using the two-fluid model. We focus on the overdamped limit and\non the effect of the network's intrinsic length scales. We calculate the decay\nrate of slow surface fluctuations, and the surface displacement in response to\na localized force. Deviations from the large-scale continuum response are found\nat length scales much larger than the network's mesh size. We discuss\nimplications for surface scattering and microrheology. We provide closed-form\nexpressions that can be used for surface microrheology -- the extraction of\nviscoelastic moduli and intrinsic length scales from the motions of tracer\nparticles lying on the surface without doping the bulk material.",
        "positive": "Microstructure and rheology of finite inertia neutrally buoyant\n  suspensions: The microstructure and rheological properties of suspensions of neutrally\nbuoyant hard spherical particles in Newtonian fluid under conditions of finite\ninertia are studied using the lattice-Boltzmann method (LBM), which is based on\na discrete Boltzmann model for the fluid and Newtonian dynamics for the\nparticles. The suspensions are subjected to simple-shear flow and the\nproperties are studied as a function of Reynolds number and volume fraction,\n$\\phi$. The inertia is characterized by the particle-scale shear flow Reynolds\nnumber $Re = \\frac{\\rho \\dot{\\gamma}a^{2}}{\\mu}$, where $a$ is the particle\nradius, $\\dot{\\gamma}$ is the shear rate and $\\rho$ and $\\mu$ are the density\nand viscosity of the fluid, respectively. The influences of inertia and of the\nvolume fraction are studied for $0.005\\leqslant Re \\leqslant 5$ and\n$0.1\\leqslant \\phi \\leqslant 0.35$. The flow-induced microstructure is studied\nusing the pair distribution function $g(\\boldsymbol{r})$. Different stress\nmechanisms, including those due to surface tractions (stresslet), acceleration,\nand the Reynolds stress due to velocity fluctuations are computed and their\ninfluence on the first and second normal stress differences, the particle\npressure and the viscosity of the suspensions are detailed. The probability\ndensity functions of particle force and torque are also presented."
    },
    {
        "anchor": "Ordering kinetics and steady states of XY-model with ferromagnetic and\n  nematic interaction: The two-dimensions XY model, undergoes the Berezinskii Kosterlitz Thouless\n(BKT) transition through unbinding of defect pairs of opposite signs. When the\ninteraction between spins is purely ferromagnetic, these defects have +-1\ncharge, whereas for pure nematic interaction between spins, they have charge\n+-1/2. Two-dimensional XY-model in the presence of both ferromagnetic and\nnematic interactions has been studied both theoretically and experimentally. In\nthis paper, we have studied dynamics of defects in the presence of both\nferromagnetic and nematic interactions on a square lattice. Varying the\nstrength of ferromagnetic and nematic interactions, we have observed behavior\nof both integer and half integer defects and based on that we propose a phase\ndiagram which exhibit three distinct regions in the phase diagram below the\ncritical TBKT : polar phase, nematic phase and coexistence phase and a\ndisordered regions above it. Also, for pure polar and pure nematic case, our\nresults show that the exponent, for algebraic decay of number of defects with\ntime, decays linearly with temperature.",
        "positive": "Modeling for heterogeneous oxidative aging of polymers using\n  coarse-grained molecular dynamics: This study presents a coarse-grained molecular dynamics simulation model to\ninvestigate the process of oxidative aging in polymers. The chemical aging\neffect is attributed to the auto-oxidation mechanism, which is initiated by\nradicals, leading to the chain scission and crosslinking of polymer chains. In\nthis study, we integrate a thermal oxidation kinetic model in the oxygen excess\nregime into the Kremer-Grest model, thereby enabling a reactive coarse-grained\nmolecular dynamics simulation to capture the process of oxidative degradation.\nOur simulation reveals that when the timescale of the characteristic reaction\nstep of oxidative degradation is shorter than the longest relaxation time of\npolymer chains, the scission sites exhibit spatial heterogeneity. This\ninnovative simulation model possesses the potential to enhance our\ncomprehension of polymer aging phenomena, thus making noteworthy contributions\nto the realm of polymer science and degradation chemistry."
    },
    {
        "anchor": "Small is beautiful, and dry: Thousands of plant and animal species have been observed to have\nsuperhydrophobic surfaces that lead to various novel behaviors [1-5]. These\nobservations have inspired attempts to create artificial superhydrophobic\nsurfaces, given such surfaces have multitudinous applications [6-13].\nSuperhydrophobicity is an enhanced effect of surface roughness and there are\nknown relationships that correlate surface roughness and superhydrophobicity,\nbased on the underlying physics. However, while these recognize the level of\nroughness they tell us little about the independent effect of its scale. Thus,\nthey are not capable of explaining why naturally occurring such surfaces\ncommonly have micron-submicron sizes. Here we report on the discovery of a new\nrelation, its physical basis and its experimental verification. The results\nreveal that scaling-down roughness into the micro-submicron range is a unique\nand elegant strategy to not only achieve superhydrophobicity but also to\nincrease its stability against environmental disturbances. This new relation\ntakes into account the previously overlooked but key fact that the accumulated\nline energy arising from the numerous solid-water-air intersections that can be\ndistributed in the apparent contact area when air packets are trapped at small\nscales on the surface can dramatically increase as the roughness scale shrinks.\nThis term can in fact become the dominant contributor to the surface energy and\nso becomes crucial for accomplishing superhydrophobicity. These findings guide\nfabrication of stable super water-repellant surfaces.",
        "positive": "Feshbach resonance in dense ultracold Fermi gases: We propose a coherent framework allowing to deal with many-body effects in\ndense ultracold Fermi gases in the presence of a Feshbach resonance. We show\nthat the simple effect of Pauli exclusion induces a strong modification of the\nbasic scattering properties, leading in particular to an energy dependence of\nthe effective scattering length on the scale of the chemical potential. This\nresults in a smearing of the Feshbach resonance and provides a natural\nexplanation for recent experimental findings."
    },
    {
        "anchor": "Optothermal pulling, trapping, and assembly of colloids using nanowire\n  plasmons: Optical excitation of colloids can be harnessed to realize soft matter\nsystems that are out of equilibrium. In this paper, we present our experimental\nstudies on the dynamics of silica colloids in the vicinity of a silver nanowire\npropagating surface plasmon polaritons (SPPs). Due to the optothermal\ninteraction, the colloids are directionally pulled towards the excitation point\nof the nanowire. Having reached this point, they are spatio-temporally trapped\naround the excitation location. By increasing the concentration of colloids in\nthe system, we observe multi-particle assembly around the nanowire. This\nprocess is thermophoretically driven and assisted by SPPs. Furthermore, we find\nsuch an assembly to be sensitive to the excitation polarization at input of the\nnanowire. Numerically-simulated temperature distribution around an illuminated\nnanowire corroborates sensitivity to the excitation polarization. Our study\nwill find relevance in exploration of SPPs-assisted optothermal pulling,\ntrapping and assembly of colloids, and can serve as test-beds of plasmon-driven\nactive matter.",
        "positive": "Nonequilibrium equation of state in suspensions of active colloids: Active colloids constitute a novel class of materials composed of\ncolloidal-scale particles locally converting chemical energy into motility,\nmimicking micro-organisms. Evolving far from equilibrium, these systems display\nstructural organizations and dynamical properties distinct from thermalized\ncolloidal assemblies. Harvesting the potential of this new class of systems\nrequires the development of a conceptual framework to describe these\nintrinsically nonequilibrium systems. We use sedimentation experiments to probe\nthe nonequilibrium equation of state of a bidimensional assembly of active\nJanus microspheres, and conduct computer simulations of a model of\nself-propelled hard disks. Self-propulsion profoundly affects the equation of\nstate, but these changes can be rationalized using equilibrium concepts. We\nshow that active colloids behave, in the dilute limit, as an ideal gas with an\nactivity-dependent effective temperature. At finite density, increasing the\nactivity is similar to increasing adhesion between equilibrium particles. We\nquantify this effective adhesion and obtain a unique scaling law relating\nactivity and effective adhesion in both experiments and simulations. Our\nresults provide a new and efficient way to understand the emergence of novel\nphases of matter in active colloidal suspensions."
    },
    {
        "anchor": "Phase coexistence in the Non-reciprocal Cahn-Hilliard model: We establish the criterion for the phase coexistence in a mixture of\nnonreciprocally interacting scalar densities. For an arbitrary number of\ncomponents the active pressure exists for a specific class of interactions, and\nwhen the free energy receives no contribution from cross couplings between\nspatial gradients of two different species. In this case, the pressure can be\nused to determine phase equilibrium, i.e. to construct binodals, and the active\nmixture can be mapped to a passive system with an effective free energy. For\ngeneral interfacial tension, the pressure changes discontinuously across a flat\ninterface which assumes the form of an active Laplace pressure in two\ndimensions.",
        "positive": "Influence of ripening and creaming on the aggregation rate of\n  dodecane-in-water nanoemulsions. Is the creaming rate an appropriate measure\n  of emulsion stability?: The behavior of four oil-in-water (O/W) ioinic nanoemulsions composed of\ndodecane, and mixtures of dodecane with squalene and tetra-chloro-ethylene is\nstudied. These nanoemulsions were stabilized with sodium dodecyl sulfate (SDS).\nThe behavior of the turbidity and the average radius of the emulsions were\nfollowed as a function of time. The results illustrate the shortcomings of\ncharacterizing the stability of emulsions by their creaming rate."
    },
    {
        "anchor": "Universal Structural Relaxation in Supercooled Liquids: One of the hallmarks of molecular dynamics in deeply supercooled liquids is\nthe non-exponential character of the relaxation functions. It has been a long\nstanding issue if 'universal' features govern the lineshape of glassy dynamics\nindependent of any particular molecular structure or interaction. In the paper,\nwe elucidate this matter by giving a comprehensive comparison of the spectral\nshape of depolarized light scattering and dielectric data of deeply supercooled\nliquids. The light scattering spectra of very different systems, e.g. hydrogen\nbonding and van der Waals liquids but also ionic systems, almost perfectly\nsuperimpose and show a generic lineshape of the structural relaxation,\napproximately following a high frequency power law $\\omega^{-1/2}$ . However,\nthe dielectric loss peak shows a more individual shape. In systems with low\ndipole moment generic behavior is also observed in the dielectric spectra,\nwhile in strongly dipolar liquids additional crosscorrelation contributions\nmask the generic structural relaxation.",
        "positive": "Crystallization of the Lewis-Wahnstr\u00f6m ortho-terphenyl model: Crystallization is observed during long molecular dynamics simulations of\nbent trimers, a molecular model proposed by Lewis and Wahnstr\\\"{o}m for\northo-terphenyl. In the crystal, the three spheres that make up the rigid\nmolecule sit near sites of a body centered cubic lattice, the trimer bond angle\nbeing almost optimal for this structure. The crystal exhibits orientational\ndisorder with the molecules aligned randomly along the three Cartesian axis (an\nexample of cubatic orientational order). The rotational and translational\nmobilities exhibit only modest decreases on crystallization, by factors of 10\nand 3 respectively. The rotational relaxation does change from Debye-like in\nthe liquid to large angle jumps in the crystal. We consider the origin of the\nsuperior glass forming ability of the the trimer over the monatomic liquid."
    },
    {
        "anchor": "Limiting propulsion of ionic microswimmers: Self-propulsion of catalytic Janus swimmers in electrolyte solutions is\ninduced by inhomogeneous ion release from their surface. Here, we consider the\nexperimentally relevant cases of particles which emit only one type of ions\n(type I) or equal fluxes of cations and anions (type II). In the limit of a\nthin electrostatic diffuse layer we derive a nonlinear outer solution for the\nelectric field and concentrations of active (i.e. released from the surface)\nand passive ionic species. We show that for swimmers of type I both the maximum\nion flux and propulsion velocity are constrained. This suggests that the\npropulsion of Janus swimmers can be optimized by tuning the concentration of\nactive ions.",
        "positive": "Directed Autonomous Motion and Chiral Separation of Self-Propelled Janus\n  Particles in Convection Roll Arrays: Self-propelled Janus particles exhibit autonomous motion thanks to engines of\ntheir own. However, due to randomly changing direction of such motion they are\nof little use for emerging nano-technological and bio-medical applications.\nHere, we numerically show that the motion of chiral active Janus can be\ndirected subjecting them to a linear array of convection rolls. Rectification\npower of self-propulsion motion here can be made more than 60% which is much\nlarger than earlier reports. We show that rectification of chiral Janus\nparticle's motion leads to conspicuous segregation of dextrogyre and levogyre\nactive particles from a racemic binary mixture. Further, we demonstrate how\nefficiently the rectification effect can be exploited to separate dextrogyre\nand levogyre particles when their intrinsic torques are distributed with\nGaussian statistics."
    },
    {
        "anchor": "Direct observation of hydrodynamic instabilities in driven non-uniform\n  colloidal dispersions: A Rayleigh-Taylor-like instability of a dense colloidal layer under gravity\nin a capillary of microfluidic dimensions is considered. We access all relevant\nlengthscales with particle-level microscopy and computer simulations which\nincorporate long-range hydrodynamic interactions between the particles. By\ntuning the gravitational driving force, we reveal a mechanism whose growth is\nconnected to the fluctuations of specific wavelengths, non-linear pattern\nformation and subsequent diffusion-dominated relaxation. Our linear stability\ntheory captures the initial regime and thus predicts mixing conditions, with\nimportant implications for fields ranging from biology to nanotechnology.",
        "positive": "Squeezing superfluid from a stone: Coupling superfluidity and elasticity\n  in a supersolid: In this work we start from the assumption that normal solid to supersolid\n(NS-SS) phase transition is continuous, and develop a phenomenological Landau\ntheory of the transition in which superfluidity is coupled to the elasticity of\nthe crystalline $^4$He lattice. We find that the elasticity does not affect the\nuniversal properties of the superfluid transition, so that in an unstressed\ncrystal the well-known $\\lambda$-anomaly in the heat capacity of the superfluid\ntransition should also appear at the NS-SS transition. We also find that the\nonset of supersolidity leads to anomalies in the elastic constants near the\ntransition; conversely, inhomogeneous strains in the lattice can induce local\nvariations of the superfluid transition temperature, leading to a broadened\ntransition."
    },
    {
        "anchor": "Micro-vorticity fluctuations affect the structure of thin fluid films: The dynamic interaction of complex fluid interfaces is highly sensitive to\nnear-contact interactions occurring at the scale of ten of nanometers. Such\ninteractions are difficult to analyse because they couple self-consistently to\nthe dynamic morphology of the evolving interface, as well as to the\nhydrodynamics of the interstitial fluid film. In this work, we show that, above\na given magnitude threshold, near-contact interactions trigger non-trivial\nmicro-vorticity patterns, which in turn affect the effective near-contact\ninteractions, giving rise to persistent fluctuating ripples at the fluid\ninterface. In such regime, near-contact interactions may significantly affect\nthe macroscopic arrangement of emulsion configurations, such as those arising\nin soft-flowing microfluidic crystals.",
        "positive": "Bidirectional Sorting of Flocking Particles in the Presence of\n  Asymmetric Barriers: We numerically demonstrate bidirectional sorting of flocking particles\ninteracting with an array of asymmetric barriers. Each particle aligns with the\naverage swimming direction of its neighbors according to the Vicsek model and\nexperiences additional steric interactions as well as repulsion from the fixed\nbarriers. We show that particles preferentially localize to one side of the\nbarrier array over time, and that the direction of this rectification can be\nreversed by adjusting the particle-particle exclusion radius or the noise term\nin the equations of motion. These results provide a conceptual basis for\nisolation and sorting of single- and multi-cellular organisms which move\ncollectively according to flocking-type interaction rules."
    },
    {
        "anchor": "Dynamics of condensation of wetting layer in time-dependent\n  Ginzburg-Landau model: The dynamics of liquid condensation on a substrate or within a capillary is\nstudied when the wetting film grows via interface-limited growth. We use a\nphenomenological time-dependent Ginzburg-Landau (TDGL)-type model with\nlong-range substrate potential. Using an order parameter, which does not\ndirectly represent the density, we can derive an analytic formula for the\ninterfacial growth velocity that is directly related to the substrate\npotential. Using this analytic expression the growth of wetting film is shown\nto conform to a power-law-type growth, which is due to the presence of a\nlong-range dispersion force.",
        "positive": "A model for approximately stretched-exponential relaxation with\n  continuously varying stretching exponents: Relaxation in glasses is often approximated by a stretched-exponential form:\n$f(t) = A \\exp [-(t/\\tau)^{\\beta}]$. Here, we show that the relaxation in a\nmodel of sheared non-Brownian suspensions developed by Cort\\'e et al. [Nature\nPhys. 4, 420 (2008)] can be well approximated by a stretched exponential with\nan exponent $\\beta$ that depends on the strain amplitude: $0.25 < \\beta < 1$.\nIn a one-dimensional version of the model, we show how the relaxation\noriginates from density fluctuations in the initial particle configurations.\nOur analysis is in good agreement with numerical simulations and reveals a\nfunctional form for the relaxation that is distinct from, but well approximated\nby, a stretched-exponential function."
    },
    {
        "anchor": "Ground state structure and interactions between dimeric 2D Wigner\n  crystals: We study the ground state ordering and interactions between two\ntwo-dimensional Wigner crystals on neutralizing charged plates by means of\ncomputer simulation. We consider crystals formed by (i) point-like charges and\n(ii) charged dimers, which mimic the screening of charged surfaces by elongated\nmultivalent ions such as aspherical globular proteins, charged dendrimers or\nshort stiff polyelectrolytes. Both systems, with point-like and dimeric ions,\ndisplay five distinct crystalline phases on increasing the interlayer distance.\nIn addition to alteration of translational ordering within the bilayer, the\nphase transitions in the dimeric system are characterized by alteration of\norientational ordering of the ions.",
        "positive": "Master equation for the probability distribution functions of forces in\n  soft particle packings: Employing molecular dynamics simulations of jammed soft particles, we study\nmicroscopic responses of force-chain networks to quasi-static isotropic\n(de)compressions. We show that not only contacts but also interparticle gaps\nbetween the nearest neighbors must be considered for the stochastic evolution\nof the probability distribution functions (PDFs) of forces, where the mutual\nexchange of contacts and interparticle gaps, i.e. opening and closing contacts,\nare also crucial to the incremental system behaviors. By numerically\ndetermining the transition rates for all changes of contacts and gaps, we\nformulate a Master equation for the PDFs of forces, where the insight one gets\nfrom the transition rates is striking: The mean change of forces reflects\nnon-affine system response, while their fluctuations obey uncorrelated Gaussian\nstatistics. In contrast, interparticle gaps are reacting mostly affine in\naverage, but imply multi-scale correlations according to a wider stable\ndistribution function."
    },
    {
        "anchor": "Potential of mean force and transient states in polyelectrolyte\n  complexation: The association between polyelectrolytes (PEs) of the same size but opposite\ncharge is systematically studied in terms of the potential of mean force (PMF)\nalong their center-of-mass reaction coordinate via coarse-grained,\nimplicit-solvent, explicit-salt computer simulations. The focus is set on the\nonset and the intermediate, transient stages of complexation. At conditions\nabove the counterion-condensation threshold, the PE association process\nexhibits a distinct sliding-rod-like behavior where the polymer chains approach\neach other by first stretching out at a critical distance close to their\ncontour length, then 'shaking hand' and sliding along each other in a parallel\nfashion, before eventually folding into a neutral complex. The essential part\nof the PMF for highly charged PEs can be very well described by a simple theory\nbased on sliding charged `Debye--H\\\"uckel' rods with renormalized charges in\naddition to an explicit entropy contribution owing to the release of condensed\ncounterions. Interestingly, at the onset of complex formation, the mean force\nbetween the PE chains is found to be discontinuous, reflecting a bimodal\nstructural behavior that arises from the coexistence of interconnected-rod and\nisolated-coil states. These two microstates of the PE complex are balanced by\nsubtle counterion release effects and separated by a free-energy barrier due to\nunfavorable stretching entropy.",
        "positive": "Cell-size distribution and scaling in a one-dimensional KJMA lattice\n  model with continuous nucleation: The Kolmogrov-Johnson-Mehl-Avrami (KJMA) growth model is considered on a\none-dimensional (1D) lattice. Cells can growth with constant speed and\ncontinuously nucleate on the empty sites. We offer an alternative, mean-field\nlike approach for describing theoretically the dynamics and derive an\nanalytical cell-size distribution function. Our method reproduces the same\nscaling laws as the KJMA theory and has the advantage that it leads to a simple\nclosed form for the cell-size distribution function. It is shown that a Weibull\ndistribution is appropriate for describing the final cell-size distribution.\nThe results are discussed in comparison with Monte Carlo simulation data."
    },
    {
        "anchor": "Tilt grain boundary instabilities in three dimensional lamellar patterns: We identify a finite wavenumber instability of a 90$^{\\circ}$ tilt grain\nboundary in three dimensional lamellar phases which is absent in two\ndimensional configurations. Both a stability analysis of the slowly varying\namplitude or envelope equation for the boundary, and a direct numerical\nsolution of an order parameter model equation are presented. The instability\nmode involves two dimensional perturbations of the planar base boundary, and is\nsuppressed for purely one dimensional perturbations. We find that both the most\nunstable wavenumbers and their growth rate increase with $\\epsilon$, the\ndimensionless distance away from threshold of the lamellar phase.",
        "positive": "Imbibition triggered by capillary condensation in nanopores: We study the spatio-temporal dynamics of water uptake by capillary\ncondensation from unsaturated vapor in mesoporous silicon layers (pore radius\n$r_\\mathrm{p} \\simeq 2$ nm), taking advantage of the local changes in optical\nreflectance as a function of water saturation. Our experiments elucidate two\nqualitatively different regimes as a function of the imposed external vapor\npressure: for low saturations, equilibration occurs via a diffusion-like\nprocess; for high saturations, an imbibition-like wetting front results in fast\nequilibration towards a fully saturated sample. We show that the imbibition\ndynamics can be described by a modified Lucas-Washburn equation that takes into\naccount the liquid stresses implied by Kelvin equation."
    },
    {
        "anchor": "Adsorption and Depletion of Polyelectrolytes from Charged Surfaces: Mean-field theory and scaling arguments are presented to model\npolyelectrolyte adsorption from semi-dilute solutions onto charged surfaces.\nUsing numerical solutions of the mean-field equations, we show that adsorption\nexists only for highly charged polyelectrolytes in low salt solutions. Simple\nscaling laws for the width of the adsorbed layer and the amount of adsorbed\npolyelectrolyte are obtained. In other situations the polyelectrolyte chains\nwill deplete from the surface. For fixed surface potential conditions, the salt\nconcentration at the adsorption--depletion crossover scales as the product of\nthe charged fraction of the polyelectrolyte f and the surface potential, while\nfor a fixed surface charge density, \\sigma, it scales as \\sigma^{2/3}f^{2/3},\nin agreement with single-chain results.",
        "positive": "Phase Diagram of Chiral Biopolymer Wigner Crystals: We study the statistical mechanics of counterion Wigner crystals associated\nwith hexagonal bundles of chiral biopolymers. We show that, due to spontaneous\nchiral symmetry breaking induced by frustration, these Wigner crystals would be\nchiral even if the biopolymers themselves were not chiral. Using a duality\ntransformation of the model onto a \"spin-charge\" Hamiltonian, we show that\nmelting of the Wigner crystal is due to the unbinding of screw dislocations and\nthat the melting temperature has a singular dependence on the intrinsic\nchirality of the biopolymers. Finally, we report that, if electrostatic\ninteractions are strongly screened, the counterions can condense in the form of\nan intermediate achiral Wigner solid phase that melts by the unbinding of\nfractional topological charges."
    },
    {
        "anchor": "Experimental observation of the Bogoliubov transformation for a\n  Bose-Einstein condensed gas: Phonons with wavevector $q/\\hbar$ were optically imprinted into a\nBose-Einstein condensate. Their momentum distribution was analyzed using Bragg\nspectroscopy with a high momentum transfer. The wavefunction of the phonons was\nshown to be a superposition of +q and -q free particle momentum states, in\nagreement with the Bogoliubov quasiparticle picture.",
        "positive": "Inelastic x-ray scattering reveals the ergodic to nonergodic transition\n  of salol, a liquid with local order: We have studied the high-frequency dynamics of salol by inelastic x-ray\nscattering over a wide temperature range between 50 and 450 K, across the glass\ntransition. We find that salol efficiently realizes the mechanism of dynamical\narrest described by the mode-coupling theory, as manifested by a cusp\nsingularity in the behaviour of the non-ergodicity parameter and a $Q$\ndependence of the critical non-ergodicity parameter that is in phase with the\nstatic structure factor. These results confront positively the mode-coupling\ntheory with liquids with local order."
    },
    {
        "anchor": "Active Dipolar Colloids in Three Dimensions: Strings, Sheets,\n  Labyrinthine Textures and Crystals: Active matter exhibits striking behaviour reminiscent of living matter and\nmolecular fluids, and has promising applications in drug delivery or mixing at\nthe micron scale. Active colloidal systems provide important models with simple\nand controllable interactions amenable to theory and computer simulation.\nExperimental work is dominated by (quasi) two--dimensional (2d) systems at\nrelatively low concentration, and rather less is known of the 3d case at\nconcentrations pertinent to motility induced phase separation or to mimic\nmorphogenesis. Here we investigate a 3d experimental system of active colloids\nin a dense suspension up to volume fractions of 0.5. The particles in our\nsystem are self-propelled in the lateral plane under an AC electric field. The\nfield in addition induces an electric dipole, and the competition between\nactivity and both steric and dipolar interactions gives rise to phase behaviour\nranging from an active gas to a dynamic labyrinthine phase as well as dense\ntetragonal and hexagonal crystals. Intermediate volume fractions are\ncharacterised by two--dimensional sheets with large fluctuations reminiscent of\nactive membranes. These active sheets break symmetry in a direction\nperpendicular to the applied field. Moreover, the relationship between electric\nfield and the particle dynamics depends in a complex and unexpected manner upon\nthe position in the state diagram.",
        "positive": "Fracture mechanical behavior of polymers: 1. Amorphous glassy state: Theoretical analyses and experiments have been carried out to investigate\nfracture behavior of glassy polymers. Our birefringence measurements quantify\nthe local stress buildup at cut tip during different stages of drawing. Based\non polymethyl methacrylate (PMMA), bisphenol A polycarbonate (PC) and\npolyethylene terephthalate (PET), we find several key results beyond the\nexisting knowledge base. (1) The inherent fracture and yield strengths\nsigma_F(inh) and sigma_Y(inh) differ little in magnitude from the breaking and\nyield stress (sigma_b and sigma_y). (2) Stress intensification (SI) near a\npre-through-cut builds up deviates from the theoretical description of linear\nelastic fracture mechanics (LEFM) upon approaching the cut tip. (3) SI meets a\nnatural cutoff below which stress ceases to increase. (4) The stress stip at\ncut tip shows a trend of approximate linear increase with the far-field load s0\nfor all three polymers and different cut size a. (5) A characteristic length\nscale P emerges from the linear relation between stip and KI. For these glassy\npolymers, P is on the order of 0.1 mm. (6) Fracture toughness of brittle\npolymers is characterized by critical stress intensity factor K_Ic =\nsigma_F(inh)(2*pi*P)1/2, revealing relevance of the two crucial quantities. (7)\nThe critical energy release rate GIc for brittle glass polymers such as PMMA is\ndetermined by the product of its work of fracture wF (of uncut specimen) and P.\n(8) The elusive fractocohesive length Lfc defined in the literature as G_Ic/w_F\nnaturally arises from the new expression for G_Ic as stated in (7), i.e., it is\nessentially P. These results suggest that a great deal of future work is\nrequired to acquire additional understanding with regards to fracture and\nfailure behaviors of plastics."
    },
    {
        "anchor": "Tracking collective cell motion by topological data analysis: By modifying and calibrating an active vertex model to experiments, we have\nsimulated numerically a confluent cellular monolayer spreading on an empty\nspace and the collision of two monolayers of different cells in an antagonistic\nmigration assay. Cells are subject to inertial forces and to active forces that\ntry to align their velocities with those of neighboring ones. In agreement with\nexperiments, spreading tests exhibit finger formation in the moving interfaces,\nswirls in the velocity field, and the polar order parameter and correlation and\nswirl lengths increase with time. Cells inside the tissue have smaller area\nthan those at the interface, as observed in recent experiments. In antagonistic\nmigration assays, a population of fluidlike Ras cells invades a population of\nwild type solidlike cells having shape parameters above and below the geometric\ncritical value, respectively. Cell mixing or segregation depends on the\njunction tensions between different cells. We reproduce experimentally observed\nantagonistic migration assays by assuming that a fraction of cells favor\nmixing, the others segregation, and that these cells are randomly distributed\nin space. To characterize and compare the structure of interfaces between cell\ntypes or of interfaces of spreading cellular monolayers in an automatic manner,\nwe apply topological data analysis to experimental data and to numerical\nsimulations. We use time series of numerical simulation data to automatically\ngroup, track and classify advancing interfaces of cellular aggregates by means\nof bottleneck or Wasserstein distances of persistent homologies. These\ntopological data analysis techniques are scalable and could be used in studies\ninvolving large amounts of data. Besides applications to wound healing and\nmetastatic cancer, these studies are relevant for tissue engineering,\nbiological effects of materials, tissue and organ regeneration.",
        "positive": "Comment on \"Layering transition in confined molecular thin films:\n  Nucleation and growth\": When fluid is confined between two molecularly smooth surfaces to a few\nmolecular diameters, it shows a large enhancement of its viscosity. From\nexperiments it seems clear that the fluid is squeezed out layer by layer. A\nsimple solution of the Stokes equation for quasi-two-dimensional confined flow,\nwith the assmption of layer-by-layer flow is found. The results presented here\ncorrect those in Phys. Rev. B, 50, 5590 (1994), and show that both the\nkinematic viscosity of the confined fluid and the coefficient of surface drag\ncan be obtained from the time dependence of the area squeezed out. Fitting our\nsolution to the available experimental data gives the value of viscosity which\nis ~7 orders of magnitude higher than that in the bulk."
    },
    {
        "anchor": "How fast do microdroplets generated during liquid-liquid phase\n  separation move in a confined 2D space?: How liquid transport occurs in confined spaces is relevant to many industrial\nand lab-scale processes, ranging from enhanced oil recovery to drug delivery\nsystems. In this work, we investigate propelling microdroplets that form from\nliquid-liquid phase separation in a quasi-2D chamber, focusing on the direction\nand speed of microdroplets in response to local composition gradients. The\nconfined ternary solution in our experiments comprises a model oil, a good\nsolvent (ethanol) and a poor solvent (water). Depending on the initial solution\ncomposition, water-rich or oil-rich microdroplets, form and move spontaneously\nas the ternary solution mixes with and is displaced by water diffusing from a\ndeep side channel. Microdroplet movement is followed in situ using high-speed\nbright-field imaging or fluorescence imaging when the solution is doped with a\ndye. Local ethanol composition gradients are estimated from the variation of\nfluorescence intensity in the local continuous liquid surrounding the mobile\nmicrodroplets. From phase separation of the ternary solution with high oil\nconcentration, mobile oil-rich microdroplets form in a water-rich zone,\naccompanying the formation of water-rich microdroplets in an oil-rich zone. The\nfast movement of oil-rich microdroplets induces directional flow transport that\nmobilizes water-rich microdroplets close to the water-rich zone. The average\nmicrodroplet speed increases with the initial oil concentration in the ternary\nsolution. The fastest speed of oil-rich microdroplets observed in our\nexperiments is ~150 ${\\mu}$m/s along the surface of a hydrophobic wall. The\npresence of a sharp ethanol composition gradient is the primary driving force\nfor the fast movement of oil-rich microdroplets in confinement. Our results\ndemonstrate the potential of enhancing liquid transport in confinement through\ncomposition gradients arising from phase separation.",
        "positive": "A Model for Aging under Deformation Field, Residual Stresses and Strains\n  in Soft Glassy Materials: A model is proposed that considers aging and rejuvenation in a soft glassy\nmaterial as respectively a decrease and an increase in free energy. The aging\nterm is weighted by inverse of characteristic relaxation time suggesting\ngreater mobility of the constituents induce faster aging in a material. A\ndependence of relaxation time on free energy is proposed, which under quiescent\nconditions, leads to power law dependence of relaxation time on waiting time as\nobserved experimentally. The model considers two cases namely, a constant\nmodulus when aging is entropy controlled and a time dependent modulus. In the\nformer and the latter cases the model has respectively two and three\nexperimentally measurable parameters that are physically meaningful. Overall\nthe model predicts how material undergoes aging and approaches rejuvenated\nstate under application of deformation field. Particularly model proposes\ndistinction between various kinds of rheological effects for different\ncombinations of parameters. Interestingly, when relaxation time evolves\nstronger than linear, the model predicts various features observed in soft\nglassy materials such as thixotropic and constant yield stress, thixotropic\nshear banding, and presence of residual stress and strain."
    },
    {
        "anchor": "The role of local structure in dynamical arrest: Amorphous solids, or glasses, are distinguished from crystalline solids by\ntheir lack of long-range structural order. At the level of two-body structural\ncorrelations, glassformers show no qualitative change upon vitrifying from a\nsupercooled liquid. Nonetheless the dynamical properties of a glass are so much\nslower that it appears to take on the properties of a solid. While many\ntheories of the glass transition focus on dynamical quantities, a solid's\nresistance to flow is often viewed as a consequence of its structure. Here we\naddress the viewpoint that this remains the case for a glass. Recent\ndevelopments using higher-order measures show a clear emergence of structure\nupon dynamical arrest in a variety of glass formers and offer the tantalising\nhope of a structural mechanism for arrest. However a rigorous fundamental\nidentification of such a causal link between structure and arrest remains\nelusive. We undertake a critical survey of this work in experiments, computer\nsimulation and theory and discuss what might strengthen the link between\nstructure and dynamical arrest. We move on to highlight the relationship\nbetween crystallisation and glass-forming ability made possible by this deeper\nunderstanding of the structure of the liquid state, and emphasize the potential\nto design materials with optimal glassforming and crystallisation ability, for\napplications such as phase-change memory. We then consider aspects of the\nphenomenology of glassy systems where structural measures have yet to make a\nlarge impact, such as polyamorphism (the existence of multiple liquid states),\naging (the time-evolution of non-equilibrium materials below their glass\ntransition) and the response of glassy materials to external fields such as\nshear.",
        "positive": "Large scale chromosome folding is stable against local changes in\n  chromatin structure: Characterizing the link between small-scale chromatin structure and\nlarge-scale chromosome folding during interphase is a prerequisite for\nunderstanding transcription. Yet, this link remains poorly investigated. Here,\nwe introduce a simple biophysical model where interphase chromosomes are\ndescribed in terms of the folding of chromatin sequences composed of\nalternating blocks of fibers with different thicknesses and flexibilities, and\nwe use it to study the influence of sequence disorder on chromosome behaviors\nin space and time. By employing extensive computer simulations,we thus\ndemonstrate that chromosomes undergo noticeable conformational changes only on\nlength-scales smaller than $10^5$ basepairs and time-scales shorter than a few\nseconds, and we suggest there might exist effective upper bounds to the\ndetection of chromosome reorganization in eukaryotes. We prove the relevance of\nour framework by modeling recent experimental FISH data on murine chromosomes."
    },
    {
        "anchor": "Raman Spectroscopic Investigation of H2, HD, and D2 Physisorption on\n  Ropes of Single-Walled, Carbon Nanotubes: We have observed the S- and Q-branch Raman spectra of H2, HD, and D2 adsorbed\nat 85K and pressures up to 8 atm on single-walled, carbon nanotubes (SWNT).\nComparative data for H2 on graphite and C60 were also collected. For each\nadsorbate, we observed a small shift in the Q-branch frequencies relative to\nthe gas-phase values. To aid in interpreting this result, we constructed an\nH2-surface potential, including van der Waals and electrostatic terms. Computed\nshifts based on this potential are in good agreement with our data.",
        "positive": "The Effect of Polyelectrolyte Adsorption on Inter-Colloidal Forces: The behavior of polyelectrolytes between charged surfaces immersed in\nsemi-dilute solutions is investigated theoretically. A continuum mean field\napproach is used for calculating numerically concentration profiles between two\nelectrodes held at a constant potential. A generalized contact theorem relates\nthe inter-surface forces to the concentration profiles. The numerical results\nshow that over-compensation of the surface charges by adsorbing\npolyelectrolytes can lead to effective attraction between equally charged\nsurfaces. Simple scaling arguments enable us to characterize qualitatively the\ninter-surface interactions as function of the fraction of charged monomers p\nand the salt concentration c_b. In the low salt regime we find strong repulsion\nat short distances, where the polymers are depleted from the inter-surface gap,\nfollowed by strong attraction when the two adsorbed layers overlap. The\nmagnitude of this attraction scales as p^{1/2} and its dominant length scale is\nproportional to a/p^{1/2}, where a is the monomer size. At larger distances the\ntwo adsorbing surfaces interact via a weak electrostatic repulsion. For strong\npolyelectrolytes at high salt concentration the polymer contribution to\nattraction at short distances scales as p/c_b^{1/2} and the length scale is\nproportional to kappa*a^2/p, where kappa^{-1} is the Debye-Huckel screening\nlength. For weak polyelectrolytes at high salt concentration the interaction is\nrepulsive for all surface separations and decays exponentially with a decay\nlength equal to kappa^{-1}. The effect of irreversible adsorption is discussed\nas well and it is shown that inter-surface attraction can be obtained in this\ncase as well."
    },
    {
        "anchor": "Coarse-grained Soft-Clusters Remain non-Diffusing in the Melt State: Melts of 3-dimensional dendritic beads-springs, namely coarse-grained\nsoft-clusters, are studied by molecular dynamics simulations. The goal is to\nelucidate the unique dynamics of giant molecules, or generally speaking,\n3-dimensional architectured polymers. When constituted by more than the\ncritical number around 200 beads, soft-clusters cannot diffuse or relax far\nabove their glass transition temperature, although relaxation can happen on the\nlevel of beads. Each soft-cluster can only rotate in the cage formed by\nneighboring soft-clusters. Such a non-diffusing state would transform to the\nliquid state at exceptionally high temperature, e.g. 10 times the glass\ntransition temperature. Agreeing with experiments, 3D hierarchies lead to\nunique dynamics, especially their divergent relaxation times with the number of\nbeads. These unique dynamics are in sharp contrast with 1-dimensional\nchain-like polymers. We name such a special state as 'cooperative glass',\nbecause of the 'cooperation' of the 3D-connected beads. The design of\nsoft-clusters may also resemble cooperative rearranging regions where\ncooperativeness is contributed by low temperature, thus offer further insights\ninto the glass problem.",
        "positive": "Influence of Rough and Smooth Walls on Macroscale Granular Segregation\n  Patterns: Size bidisperse granular materials in a spherical tumbler segregate into two\ndifferent patterns of three bands with either small particles at the equator\nand large particles at the poles or vice versa, depending upon the fill level\nin the tumbler. Here we use discrete element method (DEM) simulations with\nsupporting qualitative experiments to explore the effect of the tumbler wall\nroughness on the segregation pattern, modeling the tumbler walls as either a\nclosely packed monolayer of fixed particles resulting in a rough wall, or as a\ngeometrically smooth wall. Even though the tumbler wall is in contact with the\nflowing layer only at its periphery, the impact of wall roughness is profound.\nSmooth walls tend toward a small-large-small (SLS) band pattern at the\npole-equator-pole at all but the highest fill fractions; rough walls tend\ntoward a large-small-large (LSL) band pattern at all but the lowest fill\nfractions. This comes about because smooth walls induce poleward axial drift of\nsmall particles and an equator-directed drift for large particles, resulting in\nan SLS band pattern. On the other hand, rough walls result in both sizes of\nparticles moving poleward at the surface of the flow, but due to radial\nsegregation, small particles percolate lower in the flowing layer where there\nis a return drift toward the equator while large particles remain at the\nsurface near the pole, resulting in an LSL band pattern. The tendency toward\neither of the two band patterns depends on the fill level in the tumbler and\nthe roughness of the tumbler's bounding wall."
    },
    {
        "anchor": "Hybrid Particle-Field Molecular Dynamics Under Constant Pressure: Hybrid particle-field methods are computationally efficient approaches for\nmodelling soft matter systems. So far applications of these methodologies have\nbeen limited to constant volume conditions. Here, we reformulate particle-field\ninteractions to represent systems coupled to constant external pressure. First,\nwe show that the commonly used particle-field energy functional can be modified\nto model and parameterize the isotropic contributions to the pressure tensor\nwithout interfering with the microscopic forces on the particles. Second, we\nemploy a square gradient particle-field interaction term to model non-isotropic\ncontributions to the pressure tensor, such as in surface tension phenomena.\nThis formulation is implemented within the hybrid particle-field molecular\ndynamics approach and is tested on a series of model systems. Simulations of a\nhomogeneous water box demonstrate that it is possible to parameterize the\nequation of state to reproduce any target density for a given external\npressure. Moreover, the same parameterization is transferable to systems of\nsimilar coarse-grained mapping resolution. Finally, we evaluate the feasibility\nof the proposed approach on coarse-grained models of phospholipids, finding\nthat the term between water and the lipid hydrocarbon tails is alone sufficient\nto reproduce the experimental area per lipid in constant-pressure simulations,\nand to produce a qualitatively correct lateral pressure profile.",
        "positive": "Multifaceted design optimisation for superomniphobic surfaces: Superomniphobic textures are at the frontier of surface design for vast\narrays of applications. Despite recent significant advances in fabrication\nmethods for reentrant and doubly reentrant microstructures, design optimisation\nremains a major challenge. We overcome this in two stages. Firstly, we develop\nreadily-generalisable computational methods to systematically survey three key\nwetting properties: contact angle hysteresis, critical pressure, and minimum\nenergy wetting barrier. For each, we uncover multiple competing mechanisms,\nleading to the development of new quantitative models, and correction of\ninaccurate assumptions in prevailing models. Secondly, we combine these\nanalyses simultaneously, demonstrating the power of this strategy by optimizing\nstructures that are well-suited to overcome challenges faced by two emerging\napplications: membrane distillation and digital microfluidics. As the wetting\nproperties are antagonistically coupled, this multifaceted approach is\nessential for optimal design. When large surveys are impractical, we show that\ngenetic algorithms enable efficient optimisation, offering speedups of up to\n10,000x."
    },
    {
        "anchor": "Structure and stability of self-assembled actin-lysozyme complexes in\n  salty water: Interactions between actin, an anionic polyelectrolyte, and lysozyme, a\ncationic globular protein, have been examined using a combination of\nsynchrotron small-angle x-ray scattering and molecular dynamics simulations.\nLysozyme initially bridges pairs of actin filaments, which relax into\nhexagonally-coordinated columnar complexes comprised of actin held together by\nincommensurate one-dimensional close-packed arrays of lysozyme macroions. These\ncomplexes are found to be stable even in the presence of significant\nconcentrations of monovalent salt, which is quantitatively explained from a\nredistribution of salt between the condensed and the aqueous phases.",
        "positive": "Wrinkles Riding Waves in Soft Layered Materials: The formation of periodic wrinkles in soft layered materials due to\nmechanical instabilities is prevalent in nature and has been proposed for use\nin multiple applications. However, such phenomena have been explored\npredominantly in quasi-static settings. In this work, we measure the dynamics\nof soft elastomeric blocks with stiff surface films subjected to high-speed\nimpact, and observe wrinkles forming along with, and riding upon, waves\npropagating through the system. We analyze our measurements with\nlarge-deformation, nonlinear visco-hyperelastic Finite Element simulations\ncoupled to an analytical wrinkling model. The comparison between the measured\nand simulated dynamics shows good agreement, and suggests that inertia and\nviscoelasticity play an important role. This work encourages future studies of\nthe dynamics of surface instabilities in soft materials, including\nlarge-deformation, highly nonlinear morphologies, and may have applications to\nareas including impact mitigation, soft electronics, and the dynamics of soft\nsandwich composites."
    },
    {
        "anchor": "Chain retraction in highly entangled stretched polymer melts: We use computer simulations to study the relaxation of strongly deformed\nhighly entangled polymer melts in the non-linear viscoelastic regime, focusing\non anisotropic chain conformations after isochoric elongation. The Doi-Edwards\ntube model and its GLaMM extension, incorporating contour length fluctuation\nand convective constraint release, predict a retraction of the polymer chain\nextension in all directions, setting in immediately after deformation. This\nprediction has been challenged by experiment, simulation, and other theoretical\nstudies, questioning the general validity of the tube concept. For very long\nchains we observe the initial contraction of the chain extension parallel and\nperpendicular to the stretching direction. However, the effect is significantly\nweaker than predicted by the GLaMM model. We also show that the first\nanisotropic term of an expansion of the 2D scattering function qualitatively\nagrees to predictions of the GLaMM model, providing an option for direct\nexperimental tests.",
        "positive": "Polyelectrolytes in Solution and at Surfaces: This chapter deals with charged polymers (polyelectrolytes) in solution and\nat surfaces. The behavior of polyelectrolytes is markedly different from that\nof neutral polymers. In bulk solutions, i.e. disregarding the surface effect,\nthere are two unique features to charged polymers: first, due to the presence\nof long-ranged electrostatic repulsion between charged monomers, the polymer\nconformations are much more extended, giving rise to a very small overlap\nconcentration and high solution viscosity. Second, the presence of a large\nnumber of counter-ions increases the osmotic pressure of polyelectrolyte\nsolutions, making such polymers water soluble as is of great importance to many\napplications. At surfaces, the same interplay between monomer-monomer repulsion\nand counter-ion degrees of freedom leads to a number of special properties. In\nparticular, the adsorption behavior depends on both the concentration of\npolymers and added salt in the bulk. We first describe the adsorption behavior\nof single polyelectrolyte molecules, and discuss the necessary conditions to\nobtain an adsorbed layer and characterize its width. Depending on the stiffness\nof the polyelectrolyte, the layer can be flat and compressed or coiled and\nextended. We then proceed and discuss the adsorption of polyelectrolytes from\nsemi-dilute solutions. Mean-field theory profiles of polyelectrolyte adsorption\nare calculated as function of surface charge density (or surface potential),\nthe amount of salt in the system and the charge fraction on the chains. The\nphenomenon of charge inversion is reviewed and its relevance to the formation\nof multilayers is explained. The review ends with a short overview of the\nbehavior of grafted polyelectrolytes."
    },
    {
        "anchor": "Aging of aqueous laponite dispersions in the presence of sodium\n  polystyrene sulfonate: Aqueous suspensions of Laponite with discotic particles are well-studied and\nfind a wide range of applications in industry. A new direction of their\nimplementation is polymer composites that can exhibit improved physical\nproperties.We have studied the aging of aqueous suspensions of Laponite and\nsodium polystyrene sulfonate (PSS-Na) and both their microscopic (small-angle\nX-ray scattering, SAXS) and macroscopic (small amplitude oscillatory shear\n(SAOS) rheometry) properties. The concentration of Laponite, $C_L$, was fixed\nat 2.5% wt and concentration of PSS-Na, $C_p$, was varied within 0-0.5% wt\n(0-24.2~mM). It is shown that the adding of PSS-Na significantly accelerates\nthe aging.Nevertheless, the systems were stable against the sedimentation, and\nthe flocculation didn't occur. Polyelectrolyte induced the appearance of\nlarge-scale fractal heterogeneities, which became more compact in the course of\nthe aging. Polyelectrolyte induced the appearance of large-scale fractal\nheterogeneities, which became more compact in the course of the aging.",
        "positive": "The origin of universal cell shape variability in a confluent epithelial\n  monolayer: Cell shape is fundamental in biology. The average cell shape can influence\ncrucial biological functions, such as cell fate and division orientation. But\ncell-to-cell shape variability is often regarded as noise. In contrast, recent\nworks reveal that shape variability in diverse epithelial monolayers follows a\nnearly universal distribution. However, the origin and implications of this\nuniversality are unclear. Here, assuming contractility and adhesion are crucial\nfor cell shape, characterized via aspect ratio (AR), we develop a mean-field\nanalytical theory for shape variability. We find that a single parameter,\n$\\alpha$, containing all the system-specific details, describes the probability\ndistribution function (PDF) of AR; this leads to a universal relation between\nthe standard deviation and the average of AR. The PDF for the scaled AR is not\nstrictly but almost universal. The functional form is not related to jamming,\ncontrary to common beliefs, but a consequence of a mathematical property. In\naddition, we obtain the scaled area distribution, described by the parameter\n$\\mu$. We show that $\\alpha$ and $\\mu$ together can distinguish the effects of\nchanging physical conditions, such as maturation, on different system\nproperties. The theory is verified in simulations of two distinct models of\nepithelial monolayers and agrees well with existing experiments. We demonstrate\nthat in a confluent monolayer, average shape determines both the shape\nvariability and dynamics. Our results imply the cell shape variability is\ninevitable, where a single parameter describes both statics and dynamics and\nprovides a framework to analyze and compare diverse epithelial systems."
    },
    {
        "anchor": "Relaxation mechanisms in supercooled liquids past the Mode--Coupling\n  Crossover: Cooperatively Re--arranging Regions vs Excitations: Among the challenges in discriminating between theoretical approaches to the\nglass transition is obtaining suitable data. In particular, particle--resolved\ndata in liquids supercooled past the mode--coupling crossover has until\nrecently been hard to obtain. Here we combine nano-particle resolved\nexperiments and GPU simulation data which addresses this and investigate the\npredictions of differing theoretical approaches. We find support for both\ndynamic facilitation and thermodynamic approaches. In particular, excitations,\nthe elementary units of relaxation in dynamic facilitation theory follow the\npredicted scaling behaviour and the properties of cooperatively rearranging\nregions (CRRs) are consistent with RFOT theory. At weak supercooling there is\nlimited correlation between particles identified in excitations and CRRs, but\nthis increases very substantially at deep supercooling. We identify a timescale\nrelated to the CRRs which is coupled to the structural relaxation time and thus\ndecoupled from the excitation timescale, which remains microscopic.",
        "positive": "Bayesian determination of the effect of a deep eutectic solvent on the\n  structure of lipid monolayers: In this work, we present the first example of the self-assembly of\nphospholipid monolayers at the interface between air and an ionic solvent. Deep\neutectic solvents are a novel class of environmentally friendly non-aqueous\nroom temperature liquids with tunable properties, that have wide ranging\npotential applications and are capable of promoting the self-assembly of\nsurfactant molecules. We use a chemically-consistent Bayesian modelling of\nX-ray and neutron reflectometry measurements to show that these monolayers\nbroadly behave as they do on water. This method allows for the monolayer\nstructure to be determined, alongside the molecular volumes of the individual\nmonolayer components without the need for water-specific constraints to be\nintroduced. Furthermore, using this method we are able to better understand the\ncorrelations present between parameters in the analytical model. This example\nof a non-aqueous phospholipid monolayer has important implications for the\npotential uses of these solvents and for our understanding of how biomolecules\nbehave in the absence of water."
    },
    {
        "anchor": "Efficacy of simple continuum models for diverse granular intrusions: Granular intrusion is commonly observed in natural and human-made settings.\nUnlike typical solids and fluids, granular media can simultaneously display\nfluid-like and solid-like characteristics in a variety of intrusion scenarios.\nThis multi-phase behavior increases the difficulty of accurately modeling these\nand other yielding (or flowable) materials. Micro-scale modeling methods, such\nas DEM (Discrete Element Method), capture this behavior by modeling the media\nat the grain scale, but there is often interest in the macro-scale\ncharacterizations of such systems. We examine the efficacy of a macro-scale\ncontinuum approach in modeling and understanding the physics of various\nmacroscopic phenomena in a variety of granular intrusion cases using two basic\nfrictional yielding constitutive models. We compare predicted granular force\nresponse and material flow to experimental data in four quasi-2D intrusion\ncases: (1) depth-dependent force response in horizontal submerged-intruder\nmotion; (2) separation dependent drag variation in parallel-plate\nvertical-intrusion; (3) initial-density-dependent drag fluctuations in free\nsurface plowing, and (4) flow zone development during vertical plate intrusions\nin under-compacted granular media. Our continuum modeling approach captures the\nflow process and drag forces while providing key meso- and macro-scopic\ninsights. The modeling results are then compared to experimental data. Our\nstudy highlights how continuum modeling approaches provide an alternative for\nefficient modeling as well as a conceptual understanding of various granular\nintrusion phenomena.",
        "positive": "Geometric pumping induced by shear flow in dilute liquid crystalline\n  polymer solutions: We investigate nonlinear rheology of dilute liquid crystalline polymer\nsolutions under time dependent two-directional shear flow. We analyze the\nSmoluchowski equation, which describes the dynamics of the orientation of a\nliquid crystalline polymer, by employing technique of the full counting\nstatistics. In the adiabatic limit, we derive the expression for time\nintegrated currents generated by a Berry-like curvature. Using this expression,\nit is shown that the expectation values of the time-integrated angular velocity\nof a liquid crystalline polymer and the time-integrated stress tensor are\ngenerally not zero even if the time average of the shear rate is zero. The\nvalidity of the theoretical calculations is confirmed by direct numerical\nsimulations of the Smoluchowski equation. Nonadiabatic effects are also\ninvestigated by simulations and it is found that the time-integrated stress\ntensor depends on the speed of the modulation of the shear rate if we adopt the\nisotropic distribution as an initial state."
    },
    {
        "anchor": "Phonon spectrum and dynamical stability of a quantum degenerate\n  Bose-Fermi mixture: We calculate the phonon excitation spectrum in a zero-temperature\nboson-fermion mixture. We show how the sound velocity changes due to the\nboson-fermion interaction and we determine the dynamical stability regime of a\nhomogeneous mixture. We identify a resonant phonon-exchange interaction between\nthe fermions as the physical mechanism leading to the instability.",
        "positive": "Pattern dynamics of cohesive granular particles under a plane shear: We perform three dimensional molecular dynamics simulations of cohesive\ngranular particles under a plane shear. From the simulations, we found that the\ngranular temperature of the system abruptly decreases to zero after reaching\nthe critical temperature, where the characteristic time $t_{\\rm cl}$ is\napproximately represented by $t_{\\rm cl} \\propto (\\zeta-\\zeta_{\\rm\ncr})^{-\\beta}$ with the dissipation rate $\\zeta$, the critical dissipation rate\n$\\zeta_{\\rm cr}$ and the exponent $\\beta \\simeq 0.8$. We also found that there\nexist a variety types of clusters depending on the initial density and the\ndissipation rate."
    },
    {
        "anchor": "Electric-field-induced displacement of a charged spherical colloid\n  embedded in an elastic Brinkman medium: When an electric field is applied to an electrolyte-saturated polymer gel\nembedded with charged colloidal particles, the force that must be exerted by\nthe hydrogel on each particle reflects a delicate balance of electrical,\nhydrodynamic and elastic stresses. This paper examines the displacement of a\nsingle charged spherical inclusion embedded in an uncharged hydrogel. We\npresent numerically exact solutions of coupled electrokinetic transport and\nelastic-deformation equations, where the gel is treated as an incompressible,\nelastic Brinkman medium. This model problem demonstrates how the displacement\ndepends on the particle size and charge, the electrolyte ionic strength, and\nYoung's modulus of the polymer skeleton. The numerics are verified, in part,\nwith an analytical (boundary-layer) theory valid when the Debye length is much\nsmaller than the particle radius. Further, we identify a close connection\nbetween the displacement when a colloid is immobilized in a gel and its\nvelocity when dispersed in a Newtonian electrolyte. Finally, we describe an\nexperiment where nanometer-scale displacements might be accurately measured\nusing back-focal-plane interferometry. The purpose of such an experiment is to\nprobe physicochemical and rheological characteristics of hydrogel composites,\npossibly during gelation.",
        "positive": "Linking Rates of Folding in Lattice Models of Proteins with Underlying\n  Thermodynamic Characteristics: We investigate the sequence-dependent properties of proteins that determine\nthe dual requirements of stability of the native state and its kinetic\naccessibility using simple cubic lattice models. Three interaction schemes are\nused to describe the potentials between residues. We show that, under the\nsimulation conditions when the native basin of attraction (NBA) is stable,\nthere is an excellent correlation between folding times (\\tau_{F}) and the\ndimensionless parameter (\\sigma_{T} = (T_{\\theta} - T_{F})/T_{\\theta}), where\n(T_{\\theta}) is the collapse temperature and (T_{F}) is the folding transition\ntemperature. There is also a significant correlation between (\\tau_{F}) and\nZ-score (Z=(E_{N}-E_{ms})/\\delta), where (E_{N}) is the energy of the native\nstate, (E_{ms}) is the average energy of the ensemble of misfolded structures,\nand (\\delta) is the dispersion in contact energies. An approximate relationship\nbetween (\\sigma_{T}) and the Z-score is derived, which explains the superior\ncorrelation seen between (\\tau_{F}) and (\\sigma_{T}). For two state folders\n(\\tau_{F}) is linked to the free energy difference between the unfolded states\nand the NBA."
    },
    {
        "anchor": "Short-time dynamics and high-frequency rheology of core-shell\n  suspensions with thin-shells: Short-time dynamics and high-frequency rheology for suspensions of\nnon-overlapping core-shell particles with thin shells were analyzed. In the\nthin-shell limit, the single-particle scattering coefficients were derived and\nshown to define a unique effective radius. This result was used to justify\ntheoretically (in the thin-shell limit) the accuracy of the annulus\napproximation with the inner radius equal to the effective hydrodynamic radius\nof the core-shell particle. The two-particle virial expansion of the\ntranslational & rotational self-diffusion, sedimentation and viscosity was\nperformed. The virial coefficients were evaluated and shown to be accurately\napproximated by the effective annulus model, in contrast to the imprecise\neffective hard sphere model.",
        "positive": "Structure of DNA-Functionalized Dendrimer Nanoparticles: Atomistic molecular dynamics simulations have been carried out to reveal the\ncharacteristic features of ethylenediamine (EDA) cored protonated poly amido\namine (PAMAM) dendrimers of generation 3 (G3) and 4 (G4) that are\nfunctionalized with single stranded DNAs (ssDNAs). The four ssDNA strands that\nare attached via alkythiolate [-S (CH2)6-] linker molecule to the free amine\ngroups on the surface of the PAMAM dendrimers observed to undergo a rapid\nconformational change during the 25 ns long simulation period. From the RMSD\nvalues of ssDNAs, we find relative stability in the case of purine rich ssDNA\nstrands than pyrimidine rich ssDNA strands. The degree of wrapping of ssDNA\nstrands on the dendrimer molecule was found to be influenced by the charge\nratio of DNA and the dendrimer. As G4 dendrimer contains relatively more\npositive charge than G3 dendrimer, we observe extensive wrapping of ssDNAs on\nthe G4 dendrimer. The ssDNA strands along with the linkers are seen to\npenetrate the surface of the dendrimer molecule and approach closer to the\ncenter of the dendrimer indicating the soft sphere nature of the dendrimer\nmolecule. The effective radius of DNA-functionalized dendrimer nanoparticle was\nfound to be independent of base composition of ssDNAs and was observed to be\naround 19.5 {\\AA} and 22.4 {\\AA} when we used G3 and G4 PAMAM dendrimer as the\ncore of the nanoparticle respectively. The observed effective radius of\nDNA-functionalized dendrimer molecule apparently indicates the significant\nshrinkage in the structure that has taken place in dendrimer, linker and DNA\nstrands. As a whole our results describe the characteristic features of\nDNA-functionalized dendrimer nanoparticle and can be used as strong inputs to\ndesign effectively the DNA-dendrimer nanoparticle self-assembly for their\nactive biological applications."
    },
    {
        "anchor": "Spatiotemporal complexity of electroconvection patterns in nematic\n  liquid crystals: We investigate a number of complex patterns driven by the electro-convection\ninstability in a planarly aligned layer of a nematic liquid crystal. They are\ntraced back to various secondary instabilities of the ideal roll patterns\nbifurcating at onset of convection, whereby the basic nemato-hydrodynamic\nequations are solved by common Galerkin expansion methods. Alternatively these\nequations are systematically approximated by a set of coupled amplitude\nequations. They describe slow modulations of the convection roll amplitudes,\nwhich are coupled to a flow field component with finite vorticity perpendicular\nto the layer and to a quasi-homogeneous in-plane rotation of the director. It\nis demonstrated that the Galerkin stability diagram of the convection rolls is\nwell reproduced by the corresponding one based on the amplitude equations. The\nmain purpose of the paper is, however, to demonstrate that their direct\nnumerical simulations match surprisingly well new experiments, which serves as\na convincing test of our theoretical approach.",
        "positive": "On the molecular mechanism of surface charge amplification and related\n  phenomena at aqueous polyelectrolyte-graphene interfaces: In this communication we illustrate the occurrence of a recently reported new\nphenomenon of surface-charge amplification, SCA, (originally dubbed\novercharging, OC), [Jimenez-Angeles F. and Lozada-Cassou M., J. Phys. Chem. B,\n2004, 108, 7286] by means of molecular dynamics simulation of aqueous\nelectrolytes solutions involving multivalent cations in contact with charged\ngraphene walls and the presence of short-chain lithium polystyrene sulfonates\nwhere the solvent water is described explicitly with a realistic molecular\nmodel. We show that the occurrence of SCA in these systems, in contrast to that\nobserved in primitive models, involves neither contact co-adsorption of the\nnegatively charged macroions nor divalent cations with a large size and charge\nasymmetry as required in the case of implicit solvents. In fact the SCA\nphenomenon hinges around the preferential adsorption of water (over the\nhydrated ions) with an average dipolar orientation such that the charges of the\nwater's hydrogen and oxygen sites induce magnification rather than screening of\nthe positive-charged graphene surface, within a limited range of surface-charge\ndensity."
    },
    {
        "anchor": "Comparison of some recent Excitation Chain Arguments with the Random\n  First Order Transition Theory of Supercooled Liquids and Experiment: We compare a recent excitation chain argument for the glass transition with\nthe earlier random first order transition theory. The key equation determining\nthe activation barriers and size of cooperatively rearranging regions has the\nsame scaling form in both approaches. The random first order transition theory\nunambiguously predicts the coefficients in the equation giving results that\nagree with experiment vis a vis the correlation of activation barriers with\nthermodynamics and that also agree with experimental determination of\ncorrelation lengths following the prescription of Berthier et al. The\nexcitation chain approach, while containing more adjustable parameters\naccommodates those experimental findings only by using unphysical values for\nthose adjustable parameters.",
        "positive": "Folding pathways to crumpling in thermalized elastic frames: The mechanical properties of thermally excited two-dimensional crystalline\nmembranes can depend dramatically on their geometry and topology. A\nparticularly relevant example is the effect on the crumpling transition of\nholes in the membrane. Here we use molecular dynamics simulations to study the\ncase of elastic frames (sheets with a single large hole in the center) and find\nthat the system approaches the crumpled phase through a sequence of\norigami-like folds at decreasing length scales when temperature is increased.\nWe use normal-normal correlation functions to quantify the\ntemperature-dependent number of folds."
    },
    {
        "anchor": "Trivalent ion overcharging on electrified graphene: The structure of the electrical double layer (EDL) formed near graphene in\naqueous environments strongly impacts its performance for a plethora of\napplications, including capacitive deionization. In particular, adsorption and\norganization of multivalent counterions near the graphene interface can promote\nnonclassical behaviors of EDL including overcharging followed by co-ion\nadsorption. In this paper, we characterize the EDL formed near an electrified\ngraphene interface in dilute aqueous $YCl_3$ solution using in situ high\nresolution x-ray reflectivity (also known as crystal truncation rod (CTR)) and\nresonant anomalous x-ray reflectivity (RAXR). These interfacial-specific\ntechniques reveal the electron density profiles with molecular-scale\nresolution. We find that yttrium ions ($Y^{3+}$) readily adsorb to the\nnegatively charged graphene surface to form an extended ion profile. This ion\ndistribution resembles a classical diffuse layer but with a significantly high\nion coverage, i.e., 1 $Y^{3+}$ per 11.4 $\\pm$ 1.6 A$^2$, compared to the value\ncalculated from the capacitance measured by cyclic voltammetry (1 $Y^{3+}$ per\n~240 A$^2$). Such overcharging can be explained by co-adsorption of chloride\nthat effectively screens the excess positive charge. The adsorbed $Y^{3+}$\nprofile also shows a molecular-scale gap ($\\geq$5 A) from the top graphene\nsurfaces, which is attributed to the presence of intervening water molecules\nbetween the adsorbents and adsorbates as well as the lack of inner-sphere\nsurface complexation on chemically inert graphene. We also demonstrate\ncontrolled adsorption by varying the applied potential and reveal consistent\n$Y^{3+}$ ion position with respect to the surface and increasing cation\ncoverage with decreasing applied potential.",
        "positive": "Controlled exploration of chemical space by machine learning of\n  coarse-grained representations: The size of chemical compound space is too large to be probed exhaustively.\nThis leads high-throughput protocols to drastically subsample and results in\nsparse and non-uniform datasets. Rather than arbitrarily selecting compounds,\nwe systematically explore chemical space according to the target property of\ninterest. We first perform importance sampling by introducing a Markov chain\nMonte Carlo scheme across compounds. We then train an ML model on the sampled\ndata to expand the region of chemical space probed. Our boosting procedure\nenhances the number of compounds by a factor 2 to 10, enabled by the ML model's\ncoarse-grained representation, which both simplifies the structure-property\nrelationship and reduces the size of chemical space. The ML model correctly\nrecovers linear relationships between transfer free energies. These linear\nrelationships correspond to features that are global to the dataset, marking\nthe region of chemical space up to which predictions are reliable---a more\nrobust alternative to the predictive variance. Bridging coarse-grained\nsimulations with ML gives rise to an unprecedented database of drug-membrane\ninsertion free energies for 1.3 million compounds."
    },
    {
        "anchor": "Precursors of order in aggregates of patchy particles: We study computationally the local structure of aggregated systems of patchy\nparticles. By calculating the probability distribution functions of various\nrotational invariants we can identify the precursors of orientation order in\namorphous phase. Surprisingly, the strongest signature of local order is\nobserved for 4-patch particles with tetrahedral symmetry, not for 6-patch\nparticles with the cubic one. This trend is exactly opposite to their known\nability to crystallize. We relate this anomaly to the observation that a\ngeneric aggregate of patchy systems has coordination number close to 4. Our\nresults also suggest a significant correlation between rotational order in the\nstudied liquids with the corresponding crystalline phases, making this approach\npotentially useful for a broader range of patchy systems.",
        "positive": "Wavelet Monte Carlo dynamics: a new algorithm for simulating the\n  hydrodynamics of interacting Brownian particles: We develop a new algorithm for the Brownian dynamics of soft matter systems\nthat evolves time by spatially correlated Monte Carlo moves. The algorithm uses\nvector wavelets as its basic moves and produces hydrodynamics in the low\nReynolds number regime propagated according to the Oseen tensor. When small\nmoves are removed the correlations closely approximate the Rotne-Prager tensor,\nitself widely used to correct for deficiencies in Oseen. We also include plane\nwave moves to provide the longest range correlations, which we detail for both\ninfinite and periodic systems. The computational cost of the algorithm scales\ncompetitively with the number of particles simulated, $N$, scaling as $N\\ln N$\nin homogeneous systems and as $N$ in dilute systems. In comparisons to\nestablished lattice Boltzmann and Brownian dynamics algorithms the wavelet\nmethod was found to be only a factor of order 1 times more expensive than the\ncheaper lattice Boltzmann algorithm in marginally semi-dilute simulations,\nwhile it is significantly faster than both algorithms at large $N$ in dilute\nsimulations. We also validate the algorithm by checking it reproduces the\ncorrect dynamics and equilibrium properties of simple single polymer systems,\nas well as verifying the effect of periodicity on the mobility tensor."
    },
    {
        "anchor": "On the Helix-Coil transition in grafted chains: The helix-coil transition is modified by grafting to a surface. This\nmodification is studied for short peptides capable of forming $\\alpha$-helices.\nThree factors are involved: (i) the grafting can induced change of the boundary\nfree energy of the helical domain (ii) the van der Waals attraction between the\nhelices and (iii) the crowding induced stretching of the coils. As a result the\nhelix-coil transition acquires ``all or nothing'' characteristics. In addition\nthe transition temperature is elevated and the transition itself sharpens as\nthe grafting density increases.",
        "positive": "Memory effect of external oscillation on residual stress in a paste: We numerically investigate the stress distribution of a paste when an\nexternal oscillation is applied. The paste memorizes the oscillation as plastic\ndeformation. Due to the plastic deformation, the residual stress remains after\nthe oscillation, where the residual stress distribution depends on the number\nof cycles in the oscillation. As this number increases, the symmetry of the\nstress distribution is enhanced, which is consistent with the crack patterns\nobserved in the experiments using a drying paste."
    },
    {
        "anchor": "2D to 3D transition in soap films demonstrated by microrheology: We follow the diffusive motion of colloidal particles of diameter $d$ in soap\nfilms of varying thickness $h$ with fluorescence microscopy. Diffusion\nconstants are obtained both from one- and two-particle microrheological\nmeasurements of particle motion in these films. These diffusion constants are\nrelated to the surface viscosity of the interfaces comprising the soap films,\nby means of the Trapeznikov approximation [A. A. Trapeznikov, \\emph{PICSA}\n(1957)] and Saffman's equation for diffusion in a 2D fluid. Unphysical values\nof the surface viscosity are found for thick soap films ($h/d > 7$), indicating\na transition from 2D to 3D behavior.",
        "positive": "Pattern formation in active particle systems due to competing alignment\n  interactions: Recently, we proposed a self-propelled particle model with competing\nalignment interactions: nearby particles tend to align their velocities whereas\nthey anti-align their direction of motion with particles which are further away\n[R. Grossmann et al., Phys. Rev. Lett. 113, 258104 (2014)]. Here, we extend our\nprevious numerical analysis of the high density regime considering low particle\ndensities too. We report on the emergence of various macroscopic patterns such\nas vortex arrays, mesoscale turbulence as well as the formation of polar\nclusters, polar bands and nematically ordered states. Furthermore, we study\nanalytically the instabilities leading to pattern formation in mean-field\napproximation. We argue that these instabilities are well described by a\nreduced set of hydrodynamic equations in the limit of high density."
    },
    {
        "anchor": "Integrating local energetics into Maxwell-Calladine constraint counting\n  to design mechanical metamaterials: The Maxwell-Calladine index theorem plays a central role in our current\nunderstanding of the mechanical rigidity of discrete materials. By considering\nthe geometric constraints each material component imposes on a set of\nunderlying degrees of freedom, the theorem relates the emergence of rigidity to\nconstraint counting arguments. However, the Maxwell-Calladine paradigm is\nsignificantly limited -- its exclusive reliance on the geometric relationships\nbetween constraints and degrees of freedom completely neglects the actual\nenergetic costs of deforming individual components. To address this limitation,\nwe derive a generalization of the Maxwell-Calladine index theorem based on\nsusceptibilities that naturally incorporate local energetic properties such as\nstiffness and prestress. Using this extended framework, we investigate how\nlocal energetics modify the classical constraint counting picture to capture\nthe relationship between deformations and external forces. We then combine this\nformalism with group representation theory to design mechanical metamaterials\nwhere differences in symmetry between local energy costs and structural\ngeometry are exploited to control responses to external forces.",
        "positive": "Mechanical properties of the two-filament insulin amyloid fibril: a\n  theoretical study: We study the two-filament insulin fibril's structure by incorporating recent\nsimulation results and mechanical measurements. Our investigation suggests that\nthe persistence length measurement correlates well with the previously proposed\nstructural model, while the elasticity measurement suggests that stretching the\nfibril may involve hydrogen bond breakage. Our work illustrates an attempt to\ncorrelate nanoscale measurements with microscopic information on the quaternary\nprotein structure."
    },
    {
        "anchor": "Jamming dynamics in grain mixtures : An extended hydrodynamic approach: We study jamming in granular mixtures from the novel point of view of\nextended hydrodynamics. Using a hard sphere binary mixture model we predict\nthat a few large grains are expected to get caged more effectively in a matrix\nof small grains compared to a few small grains in a matrix of larger ones. A\nsimilar effect has been experimentally seen in the context of colloidal\nmixtures.",
        "positive": "Conformation and dynamics of a self-avoiding active flexible polymer: We investigate conformations and dynamics of a polymer considering its\nmonomers to be active Brownian particles. This active polymer shows very\nintriguing physical behavior which is absent in an active Rouse chain. The\nchain initially shrinks with active force, which starts swelling on further\nincrease in force. The shrinkage followed by swelling is attributed purely to\nexcluded-volume interactions among the monomers. In the swelling regime, chain\nshows a cross-over from the self-avoiding behavior to Rouse-behavior with\nscaling exponent $\\nu_a \\simeq 1/2$ for end-to-end distance. The\nnon-monotonicity in the structure is analysed through various physical\nquantities specifically, radial distribution function of monomers, scattering\ntime, as well as various energy calculations. The chain relaxes faster than the\nRouse chain in the intermediate force regime, with a cross-over in variation of\nrelaxation time at large active force as given by a power-law $\\tau_r \\sim\nPe^{-4/3}$ (P e is P\\'eclet number)."
    },
    {
        "anchor": "Curvature directed anchoring and defect structure of colloidal smectic\n  liquid crystals in confinement: Rod-like objects at high packing fractions can form smectic phases, where the\nrods break rotational and translational symmetry by forming lamellae. Smectic\ndefects thereby include both discontinuities in the rod orientational order\n(disclinations), as well as in the positional order (dislocations). In this\nwork, we use both experiments and simulations to probe how local and global\ngeometrical frustrations affect defect formation in hard-rod smectics. We\nconfine a particle-resolved, colloidal smectic within elliptical wells of\nvarying size and shape for a smooth variation of the boundary curvature. We\nfind that the rod orientation near a boundary - the anchoring - depends upon\nthe boundary curvature, with an anchoring transition observed at a critical\nradius of curvature approximately twice the rod length. The anchoring controls\nthe smectic defect structure. By analyzing local and global order parameters,\nand the topological charges and loops of networks made of the density maxima\n(rod centers) and density minima (rod ends), we quantify the amount of\ndisclinations and dislocations formed with varying confinement geometry. More\ncircular confinements, having only planar anchoring, promote disclinations,\nwhile more elliptical confinements, with antipodal regions of homeotropic\nanchoring, promote long-range smectic ordering and dislocation formation. Our\nfindings demonstrate how geometrical constraints can control the anchoring and\ndefect structures of liquid crystals - a principle that is applicable from\nmolecular to colloidal length scales.",
        "positive": "How capture affects polymer translocation in a solitary nanopore: DNA capture with high fidelity is an essential part of nanopore\ntranslocation. We report several important aspects of the capture process and\nsubsequent translocation of a model DNA polymer through a solid-state nanopore\nin presence of an extended electric field using the Brownian dynamics\nsimulation that enables us to record statistics of the conformations at every\nstage of the translocation process. By releasing the equilibrated DNAs from\ndifferent equipotentials, we observe that the capture time distribution depends\non the initial starting point and follows a Poisson process. The field gradient\nelongates the DNA on its way towards the nanopore and favors a successful\ntranslocation even after multiple failed threading attempts. Even in the limit\nof an extremely narrow pore, a fully flexible chain has a finite probability of\nhairpin-loop capture while this probability decreases for a stiffer chain and\npromotes single file translocation. Our in silico studies identify and\ndifferentiate characteristic distributions of the mean first passage time due\nto single file translocation from those due to translocation of different types\nof folds and provide direct evidences of the interpretation of the\nexperimentally observed folds [M. Gershow et al., Nat. Nanotech. 2, 775 (2007)\nand M. Mihovilovic et al. Phys. Rev. Letts. 110, 028102 (2013)] in a solitary\nnanopore. Finally, we show a new finding, - that a charged tag attached at the\n$5^{\\prime}$ end of the DNA enhances both the multi-scan rate as well as the\nuni-directional translocation ($5^{\\prime} \\rightarrow 3^{\\prime}$) probability\nthat would benefit the genomic barcoding and sequencing experiments."
    },
    {
        "anchor": "Emergence of multiphase condensates from a limited set of chemical\n  building blocks: Biomolecules composed of a limited set of chemical building blocks can\nco-localize into distinct, spatially segregated compartments known as\nbiomolecular condensates. While many condensates are known to form\nspontaneously via phase separation, it has been unclear how immiscible\ncondensates with precisely controlled molecular compositions assemble from a\nsmall number of chemical building blocks. We address this question by\nestablishing a connection between the specificity of biomolecular interactions\nand the thermodynamic stability of coexisting condensates. By computing the\nminimum interaction specificity required to assemble condensates with target\nmolecular compositions, we show how to design heteropolymer mixtures that\nproduce compositionally complex condensates using only a small number of\nmonomer types. Our results provide insight into how compositional specificity\narises in naturally occurring multicomponent condensates and demonstrate a\nrational algorithm for engineering complex artificial condensates from simple\nchemical building blocks.",
        "positive": "Membrane-mediated repulsion between gramicidin pores: We investigated the X-ray scattering signal of highly aligned multilayers of\nthe zwitterionic lipid 1,2-dilauroyl-sn-glycero-3-phosphatidylcholine\ncontaining pores formed by the antimicrobial peptide gramicidin as a function\nof the peptide/lipid ratio. We are able to obtain information on the structure\nfactor of the pore fluid, which then yields the interaction potential between\npores in the plane of the bilayers. Aside from a hard core with a radius close\nto the geometric radius of the pore, we find a repulsive exponential\nlipid-mediated interaction with a decay length of 2.5 {\\AA} and an amplitude\nthat decreases with the pore concentration, in agreement with the hydrophobic\nmatching hypothesis. In dilute systems, the contact value of this interaction\nis about 30 k$_B$T. Similar results are obtained for gramicidin pores inserted\nwithin bilayers formed by the nonionic surfactant pentaethylene glycol\nmonododecyl ether."
    },
    {
        "anchor": "Sedimentation and Levitation of Catalytic Active Colloids: Gravitational effects in colloidal suspensions can be easily turned off by\nmatching the density of the solid microparticles with the one of the\nsurrounding fluid. By studying the motion of catalytic microswimmers with\ntunable buoyant weight, we show that this strategy cannot be adopted for active\ncolloidal suspensions. If the average buoyant weight decreases, pronounced\naccumulation at the top wall of a sample cell is observed due to a\ncounter-alignment of the swimming velocity with the gravitational field. Even\nwhen the particles reach a flat wall, gravitational torques still determine the\nproperties of the quasi two-dimensional active motion. Our results highlight\nthe subtle role of gravity in active systems.",
        "positive": "Bilayers in amphiphilic mixtures connected by threadlike micelles: a\n  self-consistent field theory study: Binary mixtures of amphiphiles in solution can self-assemble into a wide\nrange of structures when the two species individually form aggregates of\ndifferent curvatures. A specific example of this is seen in solutions of lipid\nmixtures where the two species form lamellar structures and spherical micelles\nrespectively. Here, vesicles connected by thread-like micelles can form in a\nnarrow concentration range of the sphere-forming lipid. We present a\nself-consistent field theory (SCFT) study of these structures. Firstly, we show\nthat the addition of sphere-forming lipid to a solution of lamella-former can\nlower the free energy of cylindrical, thread-like micelles and hence encourage\ntheir formation. Next, we demonstrate the coupling between composition and\ncurvature; specifically, that increasing the concentration of sphere-former in\na system of two bilayers connected by a thread leads to a transfer of\namphiphile to the thread. We further show that the two species are segregated\nwithin the structure, with the concentration of sphere-former being\nsignificantly higher in the thread. Finally, the addition of larger amounts of\nsphere-former is found to destabilize the junctions linking the bilayers to the\ncylindrical micelle, leading to a breakdown of the connected structures. The\ndegree of segregation of the amphiphiles and the amount of sphere-former\nrequired to destabilize the junctions is shown to be sensitive to the length of\nthe hydrophilic block of the sphere-forming amphiphiles."
    },
    {
        "anchor": "Stiffening attractive suspensions with solid inclusions or granularity\n  effect in loaded colloidal gels: The elastic properties of a soft matter material can be greatly altered by\nthe presence of solid inclusions whose microscopic properties, such as their\nsize and interactions, can have a dramatic effect. In order to shed light on\nthese effects we use extensive rheology computer simulations to investigate\ncolloidal gels with solid inclusions of different size. We show that the\nelastic properties vary in a highly non trivial way as consequence of the\ninteractions between the gel backbone and the inclusions. In particular, we\nshow that the key aspects are the presence of the gel backbone and its\nmechanical alteration originated by the inclusions. To confirm our observations\nand their generality, we performed experiments on an emulsion that presents\nstrong analogies with colloidal gels and confirms the trends observed in the\nsimulations.",
        "positive": "Numerical test of the Edwards conjecture shows that all packings are\n  equally probable at jamming: In the late 1980s, Sam Edwards proposed a possible statistical-mechanical\nframework to describe the properties of disordered granular materials. A key\nassumption underlying the theory was that all jammed packings are equally\nlikely. In the intervening years it has never been possible to test this bold\nhypothesis directly. Here we present simulations that provide direct evidence\nthat at the unjamming point, all packings of soft repulsive particles are\nequally likely, even though generically, jammed packings are not. Typically,\njammed granular systems are observed precisely at the unjamming point since\ngrains are not very compressible. Our results therefore support Edwards'\noriginal conjecture. We also present evidence that at unjamming the\nconfigurational entropy of the system is maximal."
    },
    {
        "anchor": "Origin of instability in dynamic fracture: Unstable growth of cracks (rough crack surface and crack branching) in\ndynamic fracture has long been observed in various materials. Until now, there\nwas no universally agreed upon explanation for these instabilities. Here, we\ndemonstrate that: 1) Due to the non-uniform stress distribution in the cracked\nbody and the expansion of high stress region as the crack velocity increases, a\nforce-bearing cracked body can be treated as a temporary layer-like material\n(TLLM) with a \"brittle layer\" that the area of its automatically increases. 2)\nFor this TLLM, it takes only one crack for the stress in its \"brittle layer\" to\nfall below a certain value at small velocities. Coupled with the asymmetry of\nthe whole system, this results in a rough crack surface. 3) The \"brittle layer\"\nis large enough when the crack velocity reaches a certain value. Two cracks\nmust be formed, or else the stress cannot be reduced below the certain value,\nresulting in crack branching. Crack propagation can be compared to cars\ntraveling on a road: the high stress region in the cracked body provides a\n\"road\" to let cracks \"pass .\"",
        "positive": "The role of surface charge in the interaction of nanoparticles with\n  model pulmonary surfactants: Inhaled nanoparticles traveling through the airways are able to reach the\nrespiratory zone of the lungs. In such event, the incoming particles first\nenter in contact with the liquid lining the alveolar epithelium, the pulmonary\nsurfactant. The pulmonary surfactant is composed of lipids and proteins that\nare assembled into large vesicular structures. The question of the nature of\nthe biophysicochemical interaction with the pulmonary surfactant is central to\nunderstand how the nanoparticles can cross the air-blood barrier. Here we\nexplore the phase behavior of sub-100 nm particles and surfactant substitutes\nin controlled conditions. Three types of surfactant mimetics, including the\nexogenous substitute Curosurf, a drug administred to infants with respiratory\ndistress syndrome are tested together with aluminum oxide (Al2O3), silicon\ndioxide (SiO2) and polymer (latex) nanoparticles. The main result here is the\nobservation of the spontaneous nanoparticle-vesicle aggregation induced by\nCoulombic attraction. The role of the surface charges is clearly established.\nWe also evaluate the supported lipid bilayer formation recently predicted and\nfind that in the cases studied these structures do not occur. Pertaining to the\naggregate internal structure, fluorescence microscopy ascertains that the\nvesicles and particles are intermixed at the nano- to microscale. With\nparticles acting as stickers between vesicles, it is anticipated that the\npresence of inhaled nanomaterials in the alveolar spaces could significantly\nmodify the interfacial and bulk properties of the pulmonary surfactant and\ninterfere with the lung physiology."
    },
    {
        "anchor": "Bicontinuous surfaces in self-assembling amphiphilic systems: Amphiphiles are molecules which have both hydrophilic and hydrophobic parts.\nIn water- and/or oil-like solvent, they self-assemble into extended sheet-like\nstructures due to the hydrophobic effect. The free energy of an amphiphilic\nsystem can be written as a functional of its interfacial geometry, and phase\ndiagrams can be calculated by comparing the free energies following from\ndifferent geometries. Here we focus on bicontinuous structures, where one\nhighly convoluted interface spans the whole sample and thereby divides it into\ntwo separate labyrinths. The main models for surfaces of this class are triply\nperiodic minimal surfaces, their constant mean curvature and parallel surface\ncompanions, and random surfaces. We discuss the geometrical properties of each\nof these types of surfaces and how they translate into the experimentally\nobserved phase behavior of amphiphilic systems.",
        "positive": "Switching and defect dynamics in multistable liquid crystal devices: We investigate the switching dynamics of multistable nematic liquid crystal\ndevices. In particular we identify a remarkably simple 2-dimensional (2D)\ndevice which exploits hybrid alignment at the surfaces to yield a bistable\nresponse. We also consider a 3-dimensional (3D) tristable nematic device with\npatterned anchoring, recently implemented in practice, and discuss how the\ndirector and disclination patterns change during switching."
    },
    {
        "anchor": "Hydrodynamics of Immiscible Binary Fluids with Viscosity Contrast: A\n  multiparticle collision dynamics approach: We present a multiparticle collision dynamics (MPC) implementation of layered\nimmiscible fluids $A$ and $B$ of different shear viscosities separated by\nplanar interfaces. The simulated flow profile for imposed steady shear motion\nand the time-dependent shear stress functions are in excellent agreement with\nour continuum hydrodynamics results for the composite fluid. The wave-vector\ndependent transverse velocity auto-correlation functions (TVAF) in the\nbulk-fluid regions of the layers decay exponentially, and agree with those of\nsingle-phase isotropic MPC fluids. In addition, we determine the hydrodynamic\nmobilities of an embedded colloidal sphere moving steadily parallel or\ntransverse to a fluid-fluid interface, as functions of the distance from the\ninterface. The obtained mobilities are in good agreement with hydrodynamic\nforce multipoles calculations, for a no-slip sphere moving under creeping flow\nconditions near a clean, ideally flat interface. The proposed MPC fluid-layer\nmodel can be straightforwardly implemented, and it is computationally very\nefficient. Yet, owing to the spatial discretization inherent to the MPC method,\nthe model can not reproduce all hydrodynamic features of an ideally flat\ninterface between immiscible fluids.",
        "positive": "Non-linear Osmotic Brush Regime: Simulations and mean-field theory: We investigate polyelectrolyte brushes in the osmotic regime using both\ntheoretical analysis and molecular dynamics simulation techniques. In the\nsimulations at moderate Bjerrum length, we observe that the brush height varies\nweakly with grafting density, in contrast to the accepted scaling law, which\npredicts a brush thickness independent of the grafting density. We show that\nsuch behavior can be explained by considering lateral electrostatic effects\n(within the non-linear Poisson-Boltzmann theory) combined with the coupling\nbetween lateral and longitudinal degrees of freedom due to the conserved\npolymer volume (which are neglected in scaling arguments). We also take the\nnon-linear elasticity of polyelectrolyte chains into consideration, which makes\nsignificant effects as chains are almost fully stretched in the osmotic regime.\nIt is shown that all these factors lead to a non-monotonic behavior for the\nbrush height as a function of the grafting density. At large grafting\ndensities, the brush height increases with increasing the grafting density due\nto the volume constraint. At small grafting densities, we obtain a\nre-stretching of the chains for decreasing grafting density, which is caused by\nlateral electrostatic contributions and the counterion-condensation process at\npolyelectrolyte chains. These results are obtained assuming all counterions to\nbe trapped within the brush, which is valid for sufficiently long chains of\nlarge charge fraction."
    },
    {
        "anchor": "Brownian motion near a partial-slip boundary: A local probe of the\n  no-slip condition: Motivated by experimental evidence of violations of the no-slip boundary\ncondition for liquid flow in micron-scale geometries, we propose a simple,\ncomplementary experimental technique that has certain advantages over previous\nstudies. Instead of relying on externally-induced flow or probe motion, we\nsuggest that colloidal diffusivity near solid surfaces contains signatures of\nthe degree of fluid slip exhibited on those surfaces. To investigate, we\ncalculate the image system for point forces (Stokeslets) oriented perpendicular\nand parallel to a surface with a finite slip length, analogous to Blake's\nsolution for a Stokeslet near a no-slip wall. Notably, the image system for the\npoint source and perpendicular Stokeslet contain the same singularities as\nBlake's solution; however, each is distributed along a line with a magnitude\nthat decays exponentially over the slip length. The image system for the\nparallel Stokeslet involves a larger set of fundamental singularities, whose\nmagnitude does not decay exponentially from the surface. Using these image\nsystems, we determine the wall-induced correction to the diffusivity of a small\nspherical particle located `far' from the wall. We also calculate the coupled\ndiffusivities between multiple particles near a partially-slipping wall.\nBecause, in general, the diffusivity depends on `local' wall conditions,\npatterned surfaces would allow differential measurements to be obtained within\na single experimental cell, eliminating potential cell-to-cell variability\nencountered in previous experiments. In addition to motivating the proposed\nexperiments, our solutions for point forces and sources near a partial-slip\nwall will be useful for boundary integral calculations in slip systems.",
        "positive": "Charge reversal of colloidal particles: A theory is presented for the effective charge of colloidal particles in\nsuspensions containing multivalent counterions. It is shown that if colloids\nare sufficiently strongly charged, the number of condensed multivalent\ncounterion can exceed the bare colloidal charge leading to charge reversal.\nCharge renormalization in suspensions with multivalent counterions depends on a\nsubtle interplay between the solvation energies of the multivalent counterions\nin the bulk and near the colloidal surface. We find that the effective charge\nis {\\it not} a monotonically decreasing function of the multivalent salt\nconcentration. Furthermore, contrary to the previous theories, it is found that\nexcept at very low concentrations, monovalent salt hinders the charge reversal.\nThis conclusion is in agreement with the recent experiments and simulations."
    },
    {
        "anchor": "Local and global force balance for diffusiophoretic transport: Electro- and diffusio- phoresis of particles correspond respectively to the\ntransport of particles under electric field and solute concentration gradients.\nSuch interfacial transport phenomena take their origin in a diffuse layer close\nto the particle surface, and the motion of the particle is force-free. In the\ncase of electrophoresis, it is further expected that the stress acting on the\nmoving particle vanishes locally as a consequence of local electroneutrality.\nBut the argument does not apply to diffusiophoresis, which takes its origin in\nsolute concentration gradients. In this paper we investigate further the local\nand global force balance on a particle undergoing diffusiophoresis. We\ncalculate the local tension applied on the particle surface and show that,\ncounter-intuitively, the local force on the particle does not vanish for\ndiffusiophoresis, in spite of the global force being zero as expected.\nIncidentally, our description allows to clarify the osmotic balance in\ndiffusiophoresis, which has been a source of debates in the recent years. We\nexplore various cases, including hard and soft interactions, as well as porous\nparticles, and provide analytic predictions for the local force balance in\nthese various systems. The existence of local stresses may induce deformation\nof soft particles undergoing diffusiophoresis, hence suggesting applications in\nterms of particle separation based on capillary diffusiophoresis.",
        "positive": "Controllable particle migration in liquid crystal flows: We observe novel positional control of a colloidal particle in microchannel\nflow of a nematic liquid crystal. Lattice Boltzmann simulations show multiple\nequilibrium particle positions, the existence and position of which are tunable\nusing the driving pressure, in direct contrast to the classical\nSegre-Silberberg effect in isotropic liquids. In addition, particle migration\nin nematic flow occurs an order of magnitude faster. These new equilibria are\ndetermined through a balance of elastic forces, hydrodynamic lift and drag as\nwell as order-flow interactions through the defect structure around the\nparticle."
    },
    {
        "anchor": "Unraveling on Kinesin Acceleration in Intracellular Environments: A\n  Theory for Active Bath: Single molecular motor kinesin harnesses thermal and non-thermal fluctuations\nto transport various cargoes along microtubules, converting chemical energy to\ndirected movements. To describe the non-thermal fluctuations generated by the\ncomplex environment in living cells, we establish a bottom-up model to mimic\nthe intracellular environment, by introducing an active bath consisting of\nactive Ornstein-Uhlenbeck (OU) particles. Simulations of the model system show\nthat kinesin and the probe attached to it are accelerated by such active bath.\nFurther, we provide a theoretical insight into the simulation result by\nderiving a generalized Langevin equation (GLE) for the probe with a mean-field\nmethod, wherein an effective friction kernel and fluctuating noise terms are\nobtained explicitly. Numerical solutions of the GLE show very good agreement\nwith simulation results. We sample such noises, calculate their variances and\nnon-Gaussian parameters, and reveal that the dominant contribution to probe\nacceleration is attributed to noise variance.",
        "positive": "Lipophilic Force Driven Dynamics in Langmuir monolayers: In-plane\n  Coalescence and Out-of-plane Diffusion: While monolayer area fraction versus time ($A_{n}-t$) curves obtained from\nsurface pressure-area ($\\pi-A$) isotherms for desorption-dominated (DD)\nprocesses in Langmuir monolayers of fatty acids represent continuous loss,\nthose from Brewster Angle Microscopy (BAM) also show a 2D coalescence. For\nnucleation-dominated (ND) processes both techniques suggest competing\nprocesses, with BAM showing 2D coalescence alongside multilayer formation.\n$\\pi$ enhances both DD and ND with a lower cut-off for ND, while temperature\nhas a lower cut-off for DD but negligible effect on ND. Hydrocarbon chain\nlength has the strongest effect, causing a cross-over from DD to ND dynamics.\nImaging Ellipsometry (IE) of horizontally transferred films onto Si(100) shows\nStranski-Krastanov (SK) like growth for ND process in arachidic acid monolayer\nresulting in succesive stages of monolayer, trilayer, multilayer islands,\nridges from lateral island-coalescence and shallow wavelike structures from\nridge-coalescence on the film surface. These studies show that lipophilic\nattraction between hydrocarbon chains is the driving force at all stages of\nlong term monolayer dynamics."
    },
    {
        "anchor": "Depressions at the surface of an elastic spherical shell submitted to\n  external pressure: Elasticity theory calculations predict the number N of depressions that\nappear at the surface of a spherical thin shell submitted to an external\nisotropic pressure. In a model that mainly considers curvature deformations, we\nshow that N only depends on the relative volume variation. Equilibrium\nconfigurations show single depression (N=1) for small volume variations, then N\nincreases up to 6, before decreasing more abruptly due to steric constraints,\ndown to N=1 again for maximal volume variations. These predictions are\nconsistent with previously published experimental observations.",
        "positive": "Experimental Stick-Slip Behaviour in Triaxial Test on Granular Matter: This paper is concerned with the quasi-static rheology of packings of glass\nspheres of diameter d (d=0.2mm, 0.7mm or 3mm). Stick-slip behaviour is observed\non small spheres, i.e d=0.2mm & 0.7mm ; one observes also in this case a\nweakening of the rheology as the rate of deformation increases, and the larger\nthe rate the larger the weakening; this generates macroscopic instabilities and\nstick-slip. Statistics of stick-slip events have been determined, which show\nthat the larger the sample the more regular (i.e. \"periodic\") the sick-slip,\nthe faster the strain rate the less periodic the events. One concludes that\nthis stick-slip is generated at the macroscopic level and comes from the\nmacroscopic rhelogical law. However when sample is small, local fluctuations\nperturb the macroscopic events and trigger them erratically. Pacs # : 5.40 ;\n45.70 ; 62.20 ; 83.70.Fn"
    },
    {
        "anchor": "Hydrodynamic interactions in anomalous rheology of active suspensions: We explore a mechanism of the anomalous rheology of active suspensions by\nhydrodynamic simulations using model pusher swimmers. Our simulations\ndemonstrate that hydrodynamic interactions under shear flow systematically\norient swimmers along the extension direction, which is responsible for\ndetermining the global swimming states and the resulting significant viscosity\nreduction. The present results indicate the essential role of hydrodynamic\ninteractions in the elementary processes controlling the rheological properties\nin active suspensions. Furthermore, such processes may be the substance of the\npreviously proposed scenario for anomalous rheology based on the interplay\nbetween the rotational diffusivities and the external shear flow.",
        "positive": "Reversible mesoscopic model of protein adsorption: From equilibrium to\n  dynamics: We present a thermodynamically consistent mesoscopic model of protein\nadsorption at liquid-solid interfaces. First describing the equilibrium state\nunder varying protein concentration of the solution and binding conditions, we\npredict a non-trivial (non- monotonic) dependence of the experimentally\nobservable properties of the adsorbed layer (such as the surface density and\nsurface coverage) on these parameters. We subsequently proceed to develop a\ndynamical model consistent with the equilibrium description, which\nqualitatively reproduces known experimental phenomena and offers a promising\nway of studying the exchange of the adsorbed proteins by the proteins of the\nsolution."
    },
    {
        "anchor": "On the Diffuse Structure of the Toluene - Water Interface: The electric density profile along the normal to the phase interface between\naromatic hydrocarbon toluene and water has been studied by X-ray reflectometry\nusing synchrotron radiation. According to the experimental data, the width of\nthe interface under normal conditions is (5.7 +/- 0.2) Angstrom. This value is\nmuch larger than a theoretical value of (3.9 +/- 0.1) Angstrom predicted by the\ntheory of capillary waves with an interphase tension of (36.0 +/- 0.1) mN/m.\nThe observed broadening of the interface is attributed to its own diffuse\nnear-surface structure with a width no less than 4 Angstroms, which is about\nthe value previously discussed for high-molecular-weight n-alkane - water and\n1,2-dichloroethane - water interfaces.",
        "positive": "Effect of bending rigidity on the knotting of a polymer under tension: A coarse-grained computational model is used to investigate how the bending\nrigidity of a polymer under tension affects the formation of a trefoil knot.\nThermodynamic integration techniques are applied to demonstrate that the\nfree-energy cost of forming a knot has a minimum at non-zero bending rigidity.\nThe position of the minimum exhibits a power-law dependence on the applied\ntension. For knotted polymers with non-uniform bending rigidity, the knots\npreferentially localize in the region with a bending rigidity that minimizes\nthe free-energy."
    },
    {
        "anchor": "Two recipes for repelling hot water: Although a hydrophobic microtexture at a solid surface most often reflects\nrain owing to the presence of entrapped air within the texture, it is much more\nchallenging to repel hot water. As it contacts a colder material, hot water\ngenerates condensation within the cavities at the solid surface, which\neventually builds bridges between the substrate and the water, and thus\ndestroys repellency. Here we show that both \"small\" (~100 nm) and \"large\" (~10\n\\mu m) model features do reflect hot drops at any drop temperature and in the\nwhole range of explored impact velocities. Hence, we can define two structural\nrecipes for repelling hot water: drops on nanometric features hardly stick\nowing to the miniaturization of water bridges, whereas kinetics of condensation\nin large features is too slow to connect the liquid to the solid at impact.",
        "positive": "Non-adiabatic dissociation of molecules and BEC loss due to shock-waves: Recent experiments have shown the likely appearance of coherent BEC\natom-molecule oscillations in the vicinity of a Feshbach resonance. In\naddition, a new loss mechanism was observed, whereby the loss of atoms from the\nBEC is inversely dependent on the rate of change of the applied magnetic field.\nWe present here a phenomenological model which gives a good description of the\nscaling properties of this new decay process, by attributing it to\nnon-adiabatic dissociation of molecules by a propagating shock-wave. The model\nhas only two free parameters, which specify the size of the \"shocked-region\",\nand can be readily tested by future experiments."
    },
    {
        "anchor": "In silico evidence that protein unfolding is as a precursor of the\n  protein aggregation: We present a computational study on the folding and aggregation of proteins\nin aqueous environment, as function of its concentration. We show how the\nincrease of the concentration of individual protein species can induce a\npartial unfolding of the native conformation without the occurrence of\naggregates. A further increment of the protein concentration results in the\ncomplete loss of the folded structures and induces the formation of protein\naggregates. We discuss the effect of the protein interface on the water\nfluctuations in the protein hydration shell and their relevance in the\nprotein-protein interaction.",
        "positive": "Granular gas of inelastic and rough Maxwell particles: The most widely used model for granular gases is perhaps the inelastic\nhard-sphere model (IHSM), where the grains are assumed to be perfectly smooth\nspheres colliding with a constant coefficient of normal restitution. A much\nmore tractable model is the inelastic Maxwell model (IMM), in which the\nvelocity-dependent collision rate is replaced by an effective mean-field\nconstant. This simplification has been taken advantage of by many researchers\nto find a number of exact results within the IMM. On the other hand, both the\nIHSM and IMM neglect the impact of roughness -- generally present in real\ngrains -- on the dynamic properties of a granular gas. This is remedied by the\ninelastic rough hard-sphere model (IRHSM), where, apart from the coefficient of\nnormal restitution, a constant coefficient of tangential restitution is\nintroduced. In parallel to the simplification carried out when going from the\nIHSM to the IMM, we propose in this paper an inelastic rough Maxwell model\n(IRMM) as a simplification of the IRHSM. The tractability of the proposed model\nis illustrated by the exact evaluation of the collisional moments of first and\nsecond degree, and the most relevant ones of third and fourth degree. The\nresults are applied to the evaluation of the rotational-to-translational\ntemperature ratio and the velocity cumulants in the homogeneous cooling state."
    },
    {
        "anchor": "Percolation of particles on recursive lattices: (III) percolation of\n  polydisperse particles in the presence of a polymer matrix: We use a recently developed lattice model to study the percolation of\nparticles of different sizes and shapes in the presence of a polymer matrix.\nThe polymer is modeled as an infinitely long semiflexible chain. We study the\neffects of the stiffness of the polymer, the size disparity of the filler\nparticles, their aspect ratio and the interactions between fillers and polymer\non the percolation properties of the system. The lattice model is solved\nexactly on a recursive Husimi lattice. The solution represent an approximate\nsolution for a regular lattice. Our results are able to reproduce most of the\nexperimental findings that have been observed in the literature. In particular,\nwe observe how an increase in the size disparity of the filler particles\ndispersed in the matrix as well as an aincrease of their aspect ratio decreases\nthe percolation threshold.",
        "positive": "Pair correlations of an expanding superfluid Fermi gas: The pair correlation function of an expanding gas is investigated with an\nemphasis on the BEC-BCS crossover of a superfluid Fermi gas at zero\ntemperature. At unitarity quantum Monte Carlo simulations reveal the occurrence\nof a sizable bunching effect due to interactions in the spin up-down channel\nwhich, at short distances, is larger than that exhibited by thermal bosons in\nthe Hanbury-Brown and Twiss effect. We propose a local equilibrium ansatz for\nthe pair correlation function which we predict will remain isotropic during the\nexpansion even if the trapping potential is anisotropic, contrary to what\nhappens for non-interacting gases. This behavior is understood to be a\nconsequence of the violation of scaling of the pair correlation function due to\ninteractions."
    },
    {
        "anchor": "Easy orientation of diblock copolymers on self-assembled monolayers\n  using UV irradiation: A simple method based on UV/ozone treatment is proposed to control the\nsurface energy of dense grafted silane layers for orientating block copolymer\nmesophases. Our method allows one to tune the surface energy down to a fraction\nof a mN/m. We show that related to the surface, perpendicular orientation of a\nlamellar phase of a PS-PMMA diblock copolymer (neutral surface) is obtained for\na critical surface energy of 23.9-25.7 mN/m. Perpendicular cylinders are\nobtained for 24.6 mN/m and parallel cylinders for 26.8 mN/m.",
        "positive": "Thermodynamics of polymer adsorption to a flexible membrane: We analyze the structural behavior of a single polymer chain grafted to an\nattractive, flexible surface. Our model is composed of a coarse-grained\nbead-and-spring polymer and a tethered membrane. By means of extensive parallel\ntempering Monte Carlo simulations it is shown that the system exhibits a rich\nphase behavior ranging from highly ordered, compact to extended random coil\nstructures and from desorbed to completely adsorbed or even partially embedded\nconformations. These findings are summarized in a pseudophase diagram\nindicating the predominant class of conformations as a function of the external\nparameters temperature and polymer-membrane interaction strength. By comparison\nwith adsorption to a stiff membrane surface it is shown that the flexibility of\nthe membrane gives rise to qualitatively new behavior such as stretching of\nadsorbed conformations."
    },
    {
        "anchor": "Long-range dispersion effects on the water/vapor interface simulated\n  using the most common models: The long-range contribution to dispersion forces is known to have a major\nimpact on the properties of inhomogeneous fluids, and its correct treatment is\nincreasingly recognized as being a necessary requirement to avoid\ncutoff-related artefacts. Although analytical corrections for quantities like\nthe surface tension are known, these can not take into account the structural\nchanges induced by the long-range contributions. Here, we analyze the\ninterfacial properties of seven popular water models, comparing the results\nwith the cut-off version of the dispersion potential. The differences in\nsurface tension estimates are in all cases found to be less than 2 mN/m.",
        "positive": "Twofold reentrant melting in a double-Gaussian fluid: Isotropic pair potentials that are bounded at the origin have been proposed\nfrom time to time as models of the effective interaction between macromolecules\nof interest in the chemical physics of soft matter. We present a thorough study\nof the phase behavior of point particles interacting through a potential which\ncombines a bounded short-range repulsion with a much weaker attraction at\nmoderate distances, both of Gaussian shape. Notwithstanding the fact that the\nattraction acts as a small perturbation of the Gaussian-core model potential,\nthe phase diagram of the double-Gaussian model (DGM) is far richer, showing two\nfluid phases and four distinct solid phases in the case that we have studied.\nUsing free-energy calculations, the various regions of confluence of three\ndistinct phases in the DGM system have all been characterized in detail.\nMoreover, two distinct lines of reentrant melting are found, and for each of\nthem a rationale is provided in terms of the elastic properties of the solid\nphases."
    },
    {
        "anchor": "Aggregation of amphiphilic polymers in the presence of adhesive small\n  colloidal particles: The interaction of amphiphilic polymers with small colloids, capable to\nreversibly stick onto the chains, is studied. Adhesive small colloids in\nsolution are able to dynamically bind two polymer segments. This association\nleads to topological changes in the polymer network configurations, such as\nlooping and cross-linking, although the reversible adhesion permits the colloid\nto slide along the chain backbone. Previous analyses only consider static\ntopologies in the chain network. We show that the sliding degree of freedom\nensures the dominance of small loops, over other structures, giving rise to a\nnew perspective in the analysis of the problem. The results are applied to the\nanalysis of the equilibrium between colloidal particles and star polymers, as\nwell as to block copolymer micelles. The results are relevant for the\nreversible adsorption of silica particles onto hydrophilic polymers, used in\nthe process of formation of mesoporous materials of the type SBA or MCM,\ncross-linked cyclodextrin molecules threading on the polymers and forming the\nstructures known as polyrotaxanes. Adhesion of colloids on the corona of the\nlatter induce micellization and growth of larger micelles as the number of\ncolloids increases, in agreement with experimental data.",
        "positive": "Surface elastic waves in granular media under gravity: Due to the non-linearity of Hertzian contacts, the speed of sound $c$ in\ngranular matter is expected to increase with pressure as $P^{1/6}$. A static\nlayer of grains under gravity is thus stratified so that bulk waves are\nrefracted toward the surface. We investigate wave propagation in the framework\nof an elastic description taking into account the main features of granular\nmatter: non-linearity between stress and strain and existence of a yielding\ntransition. We show in this context the existence of waves localised at the\nfree surface --~like Rayleigh waves~-- but with a wave guide effect related to\nthe non-linear Hertz contact. The dispersion relationship shows a discrete\nnumber of modes which correspond to modes localized in the sagittal plane but\nalso to transverse modes. The propagation speed of these waves is finally\ncompared to recent measurements performed in the field, at the surface of a\nsand dune."
    },
    {
        "anchor": "Violation of Ericksen inequalities in lyotropic chromonic liquid\n  crystals: By analyzing elastic theory for nematic liquid crystals, we distinguish three\nregimes of elastic constants. In one regime, the Ericksen inequalities are\nsatisfied, and the ground state of the director field is uniform. In a second\nregime, certain necessary inequalities are violated, and the free energy is\nthermodynamically unstable. Between those possibilities, there is an\nintermediate regime, where the Ericksen inequalities are violated but the\nsystem is still stable. Remarkably, lyotropic chromonic liquid crystals are in\nthe intermediate regime. We investigate the nonuniform structure of the\ndirector field in that regime, show that it depends sensitively on system\ngeometry, and discuss the implications for lyotropic chromonic liquid crystals.",
        "positive": "Shedding new light on the mystery of wetting on soft solids: One of the most questionable issues in wetting is the vertical force balance\nthat is excluded in Young's law. On soft deformable solids, such as biotic\nmaterials and synthetic polymers, the vertical force of liquid leads to a\nmicroscopic protrusion of the contact line, i.e. a \"wetting ridge\". The wetting\nprinciple that determines the geometry of the ridge-tip is at the heart of the\nissues over the past half century. Here, we reveal a universal wetting\nprinciple by directly visualizing ridge-tips with high spatio-temporal\nresolution using x-ray microscopy. We find that the tip-geometry is asymmetric\nand bent, and invariant during ridge growth or by surface softness. This\nsingular geometry is explained by linking the macroscopic and microscopic\ncontact angles to Young's and Neumann's laws, respectively. Our dual-scale\nmodel would be applicable to a general framework in wetting and give new clues\nto various issues in cell-substrate interaction and elasto-capillary problems."
    },
    {
        "anchor": "Molecular shape and flexoelectricity: We performed Monte Carlo simulations of systems of wedge-shaped objects\nformed from Gay-Berne ellipsoids joined to Lennard-Jones spheres. We studied\ntwo different wedge shapes, one more asymmetric than the other. The bend and\nsplay flexoelectric coefficients were measured in the isotropic and smectic\nphases using linear response theory, and found to be negligibly small in the\nisotropic phase. We found a close connection between the properties of the\nintermolecular potential and the flexoelectric coefficients measured in the\nsmectic phase. In particular, we found negligible bend coefficients for both\nshapes and a larger magnitude of the splay coefficient for the more prominent\nwedge, in accord with Meyer's original mechanism for flexoelectricity. The less\nprominent wedge produced a splay flexoelectric coefficient with the opposite\nsign due to the attractive tail of the intermolecular potential and the\nrelative narrowness of the molecular head.",
        "positive": "How does a protein search for the specific site on DNA: the role of\n  disorder: Proteins can locate their specific targets on DNA up to two orders of\nmagnitude faster than the Smoluchowski three-dimensional diffusion rate. This\nhappens due to non-specific adsorption of proteins to DNA and subsequent\none-dimensional sliding along DNA. We call such one-dimensional route towards\nthe target \"antenna\". We studied the role of the dispersion of nonspecific\nbinding energies within the antenna due to quasi random sequence of natural\nDNA. Random energy profile for sliding proteins slows the searching rate for\nthe target. We show that this slowdown is different for the macroscopic and\nmesoscopic antennas."
    },
    {
        "anchor": "Epitaxial Transition from Gyroid to Cylinder in a Diblock Copolymer Melt: An epitaxial transition from a bicontinious double gyroid to a hexagonally\npacked cylinder structure induced by an external flow is simulated using\nreal-space dynamical self-consistent field technique. In order to simulate the\nstructural change correctly, we introduce a system size optimization technique\nby which emergence of artificial intermediate structures are suppressed. When a\nshear flow in [111] direction of the gyroid unit cell is imposed, a nucleation\nand growth of the cylinder domains is observed. We confirm that the generated\ncylindrical domains grow epitaxially to the original gyroid domains as gyroid\n$d_{\\{220\\}}$ $\\to$ cylinder $d_{\\{10\\}}$. In a steady state under the shear\nflow, the gyroid shows different reconnection processes depending on the\ndirection of the velocity gradient of the shear flow. A kinetic pathway\npreviously predicted using the self-consistent field theory where three fold\njunctions transform into five fold junctions as an intermediate state is not\nobserved.",
        "positive": "Equilibration Time Scales in Homogeneous Bose-Einstein Condensate\n  Dynamics: We study the nonequilibrium growth of a weakly interacting homogeneous Bose\ngas after a quench from a high-temperature state to a temperature below the\nBose-Einstein critical condensation temperature. We quantitatively characterize\nthe departure from thermal equilibrium and observe the presence of two\nequilibration time scales. The equilibration times are shown to be inversely\nproportional to the density."
    },
    {
        "anchor": "Granular Impact: A Grain-scale Approach: This work summarizes a series of studies on two-dimensional granular impact,\nwhere an intruding object strikes a granular material at high speed. Many\nprevious studies on granular impact have used a macroscopic force law, which is\ndominated by an inertial drag term proportional to the intruder velocity\nsquared. The primary focus here is on the microscopic force response of the\ngranular material, and how the grain-scale effects give rise to this inertial\ndrag term. We show that the inertial drag arises from intermittent collisions\nwith force-chain-like structures. We construct a simple collisional model to\nexplain the inertial drag, as well as off-axis instability and rotations.\nFinally, we show how the granular response changes when the intruder speed\napproaches $d/t_c$, leading to a failure of the inertial drag description in\nthis regime. Here, $d$ is the mean particle diameter and $t_c$ the\ncharacteristic momentum-transfer time between two grains.",
        "positive": "Non-monotonous polymer translocation time across corrugated channels:\n  comparison between Fick-Jacobs approximation and numerical simulations: We study the translocation of polymers across varying-section channels. Using\nsystematic approximations, we derive a simplified model that reduces the\nproblem of polymer translocation through varying-section channels to that of a\npoint-like particle under the action of an effective potential. Such a model\nallows us to identify the relevant parameters controlling the polymers dynamics\nand, in particular, their translocation time. By comparing our analytical\nresults with numerical simulations we show that, under suitable conditions, our\nmodel provides reliable predictions of the dynamics of both Gaussian and\nself-avoiding polymers, in two- and three-dimensional confinement. Moreover,\nboth theoretical predictions, as well Brownian dynamic results, show a\nnon-monotonous dependence of polymer translocation velocity as a function of\npolymer size, a feature that can be exploited for polymer separation."
    },
    {
        "anchor": "Dynamics of two-particle granular collisions on a surface: We experimentally examine the dynamics of two-particle collisions occuring on\na surface. We find that in two-particle collisions a standard coefficient of\nrestitution model may not capture crucial dynamics of this system. Instead, for\na typical collision, the particles involved slide relative to the substrate for\na substantial time following the collision; during this time they experience\nvery high frictional forces. The frictional forces lead to energy losses that\nare larger than the losses due to particle inelasticity. In addition, momentum\ncan be transfered to the substrate, so that the momentum of the two particles\nis not necessarily conserved. Finally, we measure the angular momenta of\nparticles immediately following the collision, and find that angular momentum\ncan be lost to the substrate following the collision as well.",
        "positive": "Brownian systems with spatially inhomogeneous activity: We generalize the Green-Kubo approach, previously applied to bulk systems of\nspherically symmetric active particles [J. Chem. Phys. 145, 161101 (2016)], to\ninclude spatially inhomogeneous activity. The method is applied to predict the\nspatial dependence of the average orientation per particle and the density. The\naverage orientation is given by an integral over the self-part of the van Hove\nfunction and a simple Gaussian approximation to this quantity yields an\naccurate analytical expression. Taking this analytical result as input to a\ndynamic density functional theory approximates the spatial dependence of the\ndensity in good agreement with simulation data. All theoretical predictions are\nvalidated using Brownian dynamics simulations."
    },
    {
        "anchor": "Penetrable-Square-Well fluids: Analytical study and Monte Carlo\n  simulations: We study structural and thermophysical properties of a one-dimensional\nclassical fluid made of penetrable spheres interacting via an attractive\nsquare-well potential. Penetrability of the spheres is enforced by reducing\nfrom infinite to finite the repulsive energy barrier in the pair potentials As\na consequence, an exact analytical solution is lacking even in one dimension.\nBuilding upon previous exact analytical work in the low-density limit [Santos\n\\textit{et al.}, Phys. Rev. E \\text{77}, 051206 (2008)], we propose an\napproximate theory valid at any density and in the low-penetrable regime. By\ncomparison with specialized Monte Carlo simulations and integral equation\ntheories, we assess the regime of validity of the theory. We investigate the\ndegree of inconsistency among the various routes to thermodynamics and explore\nthe possibility of a fluid-fluid transition. Finally we locate the dependence\nof the Fisher-Widom line on the degree of penetrability. Our results constitute\nthe first systematic study of penetrable spheres with attractions as a\nprototype model for soft systems.",
        "positive": "Phase behavior of liquid-crystal monolayers of rod-like and plate-like\n  particles: Orientational and positional ordering properties of liquid crystal monolayers\nare examined by means of Fundamental-Measure Density Functional Theory.\nParticles forming the monolayer are modeled as hard parallelepipeds of square\nsection of size $\\sigma$ and length $L$. The particle centers of mass are\nrestricted to a flat surface and three possible and mutually perpendicular\norientations (in-plane and along the layer normal) of their uniaxial axes are\nallowed. We find that the structure of the monolayer depends strongly on\nparticle shape and density. In the case of rod-like shapes, particles align\nalong the layer normal in order to achieve the lowest possible occupied area\nper particle. This phase is a uniaxial nematic even at very low densities. In\ncontrast, for plate-like particles, the lowest occupied area can be achieved by\nrandom in-plane ordering in the monolayer, i.e. planar nematic ordering takes\nplace even at vanishing densities. It is found that the random in-plane\nordering is not favorable at higher densities and the system undergoes an\nin-plane ordering transition forming a biaxial nematic phase or crystallizes.\nFor certain values of the aspect ratio, the uniaxial-biaxial nematic phase\ntransition is observed for both rod-like and plate-like shapes. The stability\nregion of the biaxial nematic phase enhances with decreasing aspect ratios for\nplate-like particles, while the rod-like particles exhibit a reentrant\nphenomenon, i.e. a sequence of uniaxial-biaxial-uniaxial nematic ordering with\nincreasing density if the aspect ratio is larger than 21.34. In addition to\nthis, packing fraction inversion is observed with increasing surface pressure\ndue to the alignment along the layers normal. At very high densities the\nnematic phase destabilizes to a nonuniform phases (columnar, smectic or\ncrystalline phases) for both shapes."
    },
    {
        "anchor": "Free energy for liquids out of equilibrium: Starting for the Stillinger and Weber expression for the free energy of\nsupercooled liquids, we extend the free energy to the case in which two time\nscales separate and the system is in quasi-equilibrium. The concept of an\neffective temperature, different from the kinetic temperature, is naturally\nintroduced. An example of hypotetical quasi-equilibrium phase diagram is\npresented for the case of SPC/E water.",
        "positive": "Insights into the flux of water in a water desalination through\n  nanopores process: Water desalination through nanopores has been shown to be a promising\nalternative to the currently water purification processes. In spite the results\nin this direction obtained by means of computational simulations were animating\nthere are still pending issues to be resolved. For example, water desalination\ninvolves macro numbers (in size and time) but in such a scale it is literally\nimpossible to attack this problem using all-atoms simulations. It is common to\nextrapolate results from nano to macro sizes in order to estimate quantities of\ninterest, which must be taken with care. Here we present a simple model which\nmimics the separation of salt from water, which may help to attack bigger\nproblems on water desalination subjects. Besides, we show that the\ninvestigation of a restrict space of parameters imposed by expensive models may\nhidden interesting, important features involved in the water desalination\nproblem. Finally, we present an analytical calculation which explains the rich\nbehaviour of the water flux through nanopores in a water-salt separation\nscenario."
    },
    {
        "anchor": "Threshold effect during dissolution of 3He inclusions in solid 4He: A pressure jump has been found at the onset of the dissolution of bcc\ninclusions in separated solid 3He-4He mixture if the crystal is overheated\nabove a certain critical value. This effect can be explained in the framework\nof a multistage dissolution process model.",
        "positive": "Elasticity and Glocality: Initiation of Embryonic Inversion in ${\\it\n  Volvox}$: Elastic objects across a wide range of scales deform under local changes of\ntheir intrinsic properties, yet the shapes are ${\\it glocal}$, set by a\ncomplicated balance between local properties and global geometric constraints.\nHere, we explore this interplay during the inversion process of the green alga\n${\\it Volvox}$, whose embryos must turn themselves inside out to complete their\ndevelopment. This process has recently been shown [S. H\\\"ohn ${\\it et~al}.$,\n${\\it Phys. Rev. Lett.}$ $\\textbf{114}$, 178101 (2015)] to be well described by\nthe deformations of an elastic shell under local variations of its intrinsic\ncurvatures and stretches, although the detailed mechanics of the process have\nremained unclear. Through a combination of asymptotic analysis and numerical\nstudies of the bifurcation behavior, we illustrate how appropriate local\ndeformations can overcome global constraints to initiate inversion."
    },
    {
        "anchor": "On The Critical Casimir Interaction Between Anisotropic Inclusions On A\n  Membrane: Using a lattice model and a versatile thermodynamic integration scheme, we\nstudy the critical Casimir interactions between inclusions embedded in a\ntwo-dimensional critical binary mixtures. For single-domain inclusions we\ndemonstrate that the interactions are very long range, and their magnitudes\nstrongly depend on the affinity of the inclusions with the species in the\nbinary mixtures, ranging from repulsive when two inclusions have opposing\naffinities to attractive when they have the same affinities. When one of the\ninclusions has no preference for either of the species, we find negligible\ncritical Casimir interactions. For multiple-domain inclusions, mimicking the\nobservations that membrane proteins often have several domains with varying\naffinities to the surrounding lipid species, the presence of domains with\nopposing affinities does not cancel the interactions altogether. Instead we can\nobserve both attractive and repulsive interactions depending on their relative\norientations. With increasing number of domains per inclusion, the range and\nmagnitude of the effective interactions decrease in a similar fashion to those\nof electrostatic multipoles. Finally, clusters formed by multiple-domain\ninclusions can result in an effective affinity patterning due to the\nanisotropic character of the Casimir interactions between the building blocks.",
        "positive": "A differential equation for the flow rate during silo discharge: Beyond\n  the Beverloo rule: We present a differential equation for the flow rate of granular materials\nduring the discharge of a silo. This is based in the energy balance of the\nvariable mass system in contrast with the traditional derivations based on\nheuristic postulates such as the free fall arch. We show that this new equation\nis consistent with the well known Beverloo rule, providing an independent\nestimate for the universal Beverloo prefactor. We also find an analytic\nexpression for the pressure under discharging conditions."
    },
    {
        "anchor": "Computing the local pressure in molecular dynamics simulations: Computer simulations of inhomogeneous soft matter systems often require\naccurate methods for computing the local pressure. We present a simple\nderivation, based on the virial relation, of two equivalent expressions for the\nlocal (atomistic) pressure in a molecular dynamics simulation. One of these\nexpressions, previously derived by other authors via a different route,\ninvolves summation over interactions between particles within the region of\ninterest; the other involves summation over interactions across the boundary of\nthe region of interest. We illustrate our derivation using simulations of a\nsimple osmotic system; both expressions produce accurate results even when the\nregion of interest over which the pressure is measured is very small.",
        "positive": "From molecular to multi-asperity contacts: how roughness bridges the\n  friction scale gap: While friction stems from the fundamental interactions between atoms at a\ncontact interface, its best descriptions at the macroscopic scale remain\nphenomenological. The so called \"rate-and-state\" models, which specify the\nfriction response in terms of the relative sliding velocity and the \"age\" of\nthe contact interface, fail to uncover the nano-scale mechanisms governing the\nmacro-scale response, while models of friction at the atomic scale often\noverlook how roughness can alter the friction behavior. Here we bridge this gap\nbetween nano and macro descriptions of friction by correlating the physical\norigin of macroscopic friction to the existence, due to nanometric roughness,\nof contact junctions between adsorbed monolayers. Their dynamics, as we show,\nemerges from molecular motion. Through coupled experimental and atomic\nsimulations, we highlight that transient friction overshoots its steady-state\nvalue after the system is allowed to rest, with the friction force decaying to\na steady-state value over a distance of a few nanometers, much smaller than the\njunction size, even with a root-mean-square roughness of 0.6 nm. We demonstrate\nhow this transient decay is intrinsically related to the evolution of the\nnumber of cross-surface attractive physical links between adsorbed molecules on\nrough surfaces. We also show that roughness is a sufficient condition for the\nappearance of frictional aging. In systems that show structural aging, this\npaints contact junctions as a key component in the observation of the transient\nfriction overshoot, and shows how infrajunction molecular motion can control\nthe macroscopic response."
    },
    {
        "anchor": "Intrinsic friction of adsorbed monolayers: In the present paper we overview our recent results on intrinsic frictional\nproperties of adsorbed monolayers, composed of mobile hard-core particles\nundergoing continuous exchanges with a vapor phase. Within the framework of a\ndynamical master equation approach, describing the time evolution of the\nsystem, we determine in the most general form the terminal velocity of some\nbiased impure molecule - the tracer particle (TP), constrained to move inside\nthe adsorbed monolayer probing its frictional properties, define the frictional\nforces as well as the particles density distribution in the monolayer. Results\nfor one-dimensional solid substrates, appropriate to adsorbtion on polymer\nchains, are compared against the Monte Carlo simulation data, which confirms\nour analytical predictions.",
        "positive": "Coupling of transverse and longitudinal response in stiff polymers: The time-dependent transverse response of stiff polymers, represented as\nweakly-bending wormlike chains (WLCs), is well-understood on the linear level,\nwhere transverse degrees of freedom evolve independently from the longitudinal\nones. We show that, beyond a characteristic time scale, the nonlinear coupling\nof transverse and longitudinal motion in an inextensible WLC significantly\nweakens the polymer response compared to the widely used linear response\npredictions. The corresponding feedback mechanism is rationalized by scaling\narguments and quantified by a multiple scale approach that exploits an inherent\nseparation of transverse and longitudinal correlation length scales. Crossover\nscaling laws and exact analytical and numerical solutions for characteristic\nresponse quantities are derived for different experimentally relevant setups.\nOur findings are applicable to cytoskeletal filaments as well as DNA under\ntension."
    },
    {
        "anchor": "Experimental Demonstration of Nonuniform Frequency Distributions of\n  Granular Packings: We developed a novel experimental technique to generate mechanically stable\n(MS) packings of frictionless granular disks. We performed a series of\ncoordinated experiments and numerical simulations to enumerate the MS packings\nin small 2D systems composed of bidisperse disks. We find that frictionless MS\npackings occur as discrete, well-separated points in configuration space and\nobtain excellent quantitative agreement between MS packings generated in\nexperiments and simulations. In addition, we observe that MS packing\nprobabilities can vary by many orders of magnitude and are robust with respect\nto the packing-generation procedure. These results suggest that the most\nfrequent MS packings may dominate the structural and mechanical properties of\ngranular systems. We argue that these results for small systems represent a\ncrucial first-step in constructing a statistical description for large granular\nsystems from the `bottom-up'.",
        "positive": "Spectral representation of the effective dielectric constant of graded\n  composites: We generalize the Bergman-Milton spectral representation, originally derived\nfor a two-component composite, to extract the spectral density function for the\neffective dielectric constant of a graded composite. This work has been\nmotivated by a recent study of the optical absorption spectrum of a graded\nmetallic film [Applied Physics Letters, 85, 94 (2004)] in which a broad\nsurface-plasmon absorption band has been shown to be responsible for enhanced\nnonlinear optical response as well as an attractive figure of merit. It turns\nout that, unlike in the case of homogeneous constituent components, the\ncharacteristic function of a graded composite is a continuous function because\nof the continuous variation of the dielectric function within the constituent\ncomponents. Analytic generalization to three dimensional graded composites is\ndiscussed, and numerical calculations of multilayered composites are given as a\nsimple application."
    },
    {
        "anchor": "Hamiltonian formulation of the maximal valence model for liquid\n  polyamorphism: Liquid-liquid phase transitions have been found experimentally or proposed to\nexist based on computer simulations in many compounds such as water, hydrogen,\nsulfur, phosphorus, carbon, silica, and silicon. Recently introduced maximal\nvalence model implemented via discrete molecular dynamics (DMD) provides simple\ngeneric mechanism of the liquid-liquid phase transitions for all these diverse\ncases. Here we will show that certain variants of the maximal valence model\nhave a well defined Hamiltonian i.e a unique algorithm by which the potential\nenergy of the system of particles can be computed solely from the coordinates\nof the particles and is thus equivalent to a complex multi-body potential. We\nwill present several examples of the model which can be used to reproduce\nliquid-liquid phase transition in systems with maximal valence $z=1$\n(hydrogen), $z=2$ (sulfur) and $z=4$ (water), where $z$ is the maximal valence,\ni.e. the maximal number of bonds an atom is allowed to have. The maximal\nvalence model can be modified to forbid not only too large valences but also\ntoo low valences. In the case of sulfur, we forbid also the formation of\nmonomers, thus restricting the valence $v$ of an atom to be within an interval\n$1=v_{min}\\leq v\\leq v_{max}\\equiv z=2$.",
        "positive": "A simple approach for charge renormalization of highly charged\n  macro-ions: We revisit the popular notion of effective or renormalized charge, which is a\nconcept of central importance in the field of highly charged colloidal or\npolyelectrolyte solutions. Working at the level of a linear Debye-H\\\"uckel like\ntheory only, we propose a simple, efficient and versatile method to predict the\nsaturated amount of charge renormalization, which is however a non-linear\neffect arising at strong electrostatic coupling. The results are successfully\ntested against the numerical solutions of Poisson-Boltzmann theory for polyions\nof various shapes (planar, cylindrical and spherical), both in the infinite\ndilution limit or in confined geometry, with or without added electrolyte. Our\napproach, accurate for monovalent micro-ions in solvents like water, is finally\nconfronted against experimental results, namely the crystallization of charged\ncolloidal suspensions and the osmotic coefficient of B-DNA solutions."
    },
    {
        "anchor": "Interfacial Layers between Ion and Water Detected by Terahertz\n  Spectroscopy: Dynamic fluctuations in hydrogen-bond network of water occur from femto- to\nnano-second timescale and provides insights into structural/dynamical aspects\nof water at ion-water interfaces. Employing terahertz spectroscopy assisted\nwith molecular dynamics simulations, we study aqueous chloride solutions of\nfive monovalent cations, namely, Li, Na, K, Rb and Cs. We show that ions modify\nthe behavior of surrounding water molecules and form interfacial layers of\nwater around them with physical properties distinct from that of bulk water.\nSmall cations with high charge densities influence the kinetics of water well\nbeyond the first solvation shell. At terahertz frequencies, we observe an\nemergence of fast relaxation processes of water with their magnitude following\nthe ionic order Cs>Rb>K>Na>Li, revealing an enhanced population density of\nweakly coordinated water at ion-water interface. The results shed light on the\nstructure breaking tendency of monovalent cations and provide insights into the\nproperties of ionic solutions at the molecular level.",
        "positive": "A Microstructural View of Burrowing with RoboClam: RoboClam is a burrowing technology inspired by Ensis directus, the Atlantic\nrazor clam. Atlantic razor clams should only be strong enough to dig a few\ncentimeters into the soil, yet they burrow to over 70 cm. The animal uses a\nclever trick to achieve this: by contracting its body, it agitates and locally\nfluidizes the soil, reducing the drag and energetic cost of burrowing. RoboClam\ntechnology, which is based on the digging mechanics of razor clams, may be\nvaluable for subsea applications that could benefit from efficient burrowing,\nsuch as anchoring, mine detonation, and cable laying. We directly visualize the\nmovement of soil grains during the contraction of RoboClam, using a novel\nindex-matching technique along with particle tracking. We show that the size of\nthe failure zone around contracting RoboClam, can be theoretically predicted\nfrom the substrate and pore fluid properties, provided that the timescale of\ncontraction is sufficiently large. We also show that the nonaffine motions of\nthe grains are a small fraction of the motion within the fluidized zone,\naffirming the relevance of a continuum model for this system, even though the\ngrain size is comparable to the size of RoboClam."
    },
    {
        "anchor": "Formation and Decay of Vortex Lattices in Bose-Einstein Condensates at\n  Finite Temperatures: The dynamics of vortex lattices in stirred Bose-Einstein condensates have\nbeen studied at finite temperatures. The decay of the vortex lattice was\nobserved non-destructively by monitoring the centrifugal distortions of the\nrotating condensate. The formation of the vortex lattice could be deduced from\nthe increasing contrast of the vortex cores observed in ballistic expansion. In\ncontrast to the decay, the formation of the vortex lattice is insensitive to\ntemperature change.",
        "positive": "Interpretation of Pulsed-Field-Gradient NMR in Terms of Molecular\n  Displacements: The relationship for Pulsed-Field-Gradient NMR between the amplitude $I(t)$\nof the spin echo and the molecular displacement ${\\bf X}(t)$ is examined.\n$I(t)$ of a single species in a simple solution is determined by the\nmean-square displacement $\\bar{X(t)^{2}}$. With polydisperse species, or\nmolecular probes in complex fluids showing memory effects, $I(t)$ in general\nincludes large contributions from all higher even moments $\\bar{X(t)^{2n}}$.\nConditions under which the NMR signal is indeed determined by the molecular\nmean-square displacement are noted. A diagnostic that sometimes identifies when\nthese conditions are not met is presented."
    },
    {
        "anchor": "Collective states of active matter with stochastic reversals: emergent\n  chiral states and spontaneous current switching: We study collective dynamical behavior of active particles with topological\ninteractions and directional reversals. Surprising phenomena are shown to\nemerge as the interaction relaxation time is varied relative to the reversal\nrate, such as spontaneous formation of collective chiral states due to phase\nsynchronization, and collective directional reversals in the presence of\nconfinement. The results have a direct relevance to modelling and understanding\ncollective reversals and synchronization phenomena in active matter.",
        "positive": "A unified analysis of nano-to-microscale particle dispersion in tubular\n  blood flow: Transport of solid particles in blood flow exhibits qualitative differences\nin the transport mechanism when the particle varies from nanoscale to\nmicroscale size comparable to the red blood cell (RBC). The effect of\nmicroscale particle margination has been investigated by several groups. Also,\nthe transport of nanoscale particles (NPs) in blood has received considerable\nattention in the past. This study attempts to bridge the gap by quantitatively\nshowing how the transport mechanism varies with particle size from nano- to\nmicroscale. Using a three-dimensional (3D) multiscale method, the dispersion of\nparticles in microscale tubular flows is investigated for various hematocrits,\nvessel diameters and particle sizes. NPs exhibit a nonuniform,\nsmoothly-dispersed distribution across the tube radius due to severe Brownian\nmotion. The near-wall concentration of NPs can be moderately enhanced by\nincreasing hematocrit and confinement. Moreover, there exists a critical\nparticle size ($\\sim$1 $\\mu$m) that leads to excessive retention of particles\nin the cell-free region near the wall, i.e., margination. Above this threshold,\nthe margination propensity increases with the particle size. The dominance of\nRBC-enhanced shear-induced diffusivity (RESID) over Brownian diffusivity (BD)\nresults in 10 times higher radial diffusion rates in the RBC-laden region\ncompared to that in the cell-free layer, correlated with the high margination\npropensity of microscale particles. This work captures the particle\nsize-dependent transition from Brownian-motion dominant dispersion to\nmargination using a unified 3D multiscale computational approach, and\nhighlights the linkage between the radial distribution of RESID and the\nmargination of particles in confined blood flows."
    },
    {
        "anchor": "Comment on \"Magnetoviscosity and relaxation in ferrofluids\": It is shown and discussed how the conventional system of hydrodynamic\nequations for ferrofluids was derived. The set consists of the equation of\nfluid motion, the Maxwell equations, and the magnetization equation. The latter\nwas recently revised by Felderhof [Phys. Rev. E, v.62, p.3848 (2000)]. His\nphenomenological magnetization equation looks rather like corresponding\nShliomis' equation, but leads to wrong consequences for the dependence of\nferrofluid viscosity and magnetization relaxation time on magnetic field.",
        "positive": "Hydrodynamic interactions and Brownian forces in colloidal suspensions:\n  Coarse-graining over time and length-scales: We describe in detail how to implement a coarse-grained hybrid Molecular\nDynamics and Stochastic Rotation Dynamics simulation technique that captures\nthe combined effects of Brownian and hydrodynamic forces in colloidal\nsuspensions. The importance of carefully tuning the simulation parameters to\ncorrectly resolve the multiple time and length-scales of this problem is\nemphasized. We systematically analyze how our coarse-graining scheme resolves\ndimensionless hydrodynamic numbers such as the Reynolds number, the Schmidt\nnumber, the Mach number, the Knudsen number, and the Peclet number. The many\nBrownian and hydrodynamic time-scales can be telescoped together to maximize\ncomputational efficiency while still correctly resolving the physically\nrelevant physical processes. We also show how to control a number of numerical\nartifacts, such as finite size effects and solvent induced attractive depletion\ninteractions. When all these considerations are properly taken into account,\nthe measured colloidal velocity auto-correlation functions and related self\ndiffusion and friction coefficients compare quantitatively with theoretical\ncalculations. By contrast, these calculations demonstrate that, notwithstanding\nits seductive simplicity, the basic Langevin equation does a remarkably poor\njob of capturing the decay rate of the velocity auto-correlation function in\nthe colloidal regime, strongly underestimating it at short times and strongly\noverestimating it at long times. Finally, we discuss in detail how to map the\nparameters of our method onto physical systems, and from this extract more\ngeneral lessons that may be relevant for other coarse-graining schemes such as\nLattice Boltzmann or Dissipative Particle Dynamics."
    },
    {
        "anchor": "Ferroelectricity, SSFLC, bistability and all that: In the book \"Ferroelectric and Antiferroelectric Liquid Crystals\" by S. T.\nLagerwall, the concept \"polar liquid crystals\" is proposed for the concept\nearlier known as \"ferroelectric liquid crystals\", reserving the word\n\"ferroelectric liquid crystals\" for the case of \"surface stabilization\". Thus\nLagerwall in this way, by redefinition, becomes the coinventor of\n\"ferroelectric liquid crystals\". The trouble is that a closer look on the\ninvention reveals a state of bad logic and a total confusion. The concepts\n\"polar\", \"ferroelectric\", \"hysteresis\", \"SSFLC\" and \"bistability\" are essential\nin the writing of Lagerwall, but these words are not used in a rigorous way.\nAlso the pictorial evidence used by Lagerwall to illustrate the discovery of\nsurface stabilized liquid crystals raises several questions. An alternative\nview of the physics of SSFLC cells is presented.",
        "positive": "Phase-ordering dynamics of the Gay-Berne nematic liquid crystal: Phase-ordering dynamics in nematic liquid crystals has been the subject of\nmuch active investigation in recent years in theory, experiments and\nsimulations. With a rapid quench from the isotropic to nematic phase a large\nnumber of topological defects are formed and dominate the subsequent\nequilibration process. We present here the results of a molecular dynamics\nsimulation of the Gay-Berne model of liquid crystals after such a quench in a\nsystem with 65536 molecules. Twist disclination lines as well as type-1 lines\nand monopoles were observed. Evidence of dynamical scaling was found in the\nbehavior of the spatial correlation function and the density of disclination\nlines. However, the behavior of the structure factor provides a more sensitive\nmeasure of scaling, and we observed a crossover from a defect dominated regime\nat small values of the wavevector to a thermal fluctuation dominated regime at\nlarge wavevector."
    },
    {
        "anchor": "Microtubules: Montroll's kink and Morse vibrations: Using a version of Witten's supersymmetric quantum mechanics proposed by\nCaticha, we relate Montroll's kink to a traveling, asymmetric Morse double-well\npotential suggesting in this way a connection between kink modes and\nvibrational degrees of freedom along microtubules",
        "positive": "Modeling Multi-Cellular Dynamics Regulated by ECM-Mediated Mechanical\n  Communication via Active Particles with Polarized Effective Attraction: Collective cell migration is crucial to many physiological and pathological\nprocesses. Recent experimental studies have indicated that the active traction\nforces generated by migrating cells in fibrous extracellular matrix (ECM) can\nmechanically remodel the ECM, enabling long-range propagation of cellular\nforces and leading to correlated migration dynamics regulated by the mechanical\ncommunication among the cells. Motivated by these experimental discoveries, we\ndevelop an active-particle model with polarized effective attractions (APPA)\nfor modeling emergent multi-cellular migration dynamics regulated by\nECM-mediated mechanical communications. Active particles with polarized\npairwise attractions exhibit enhanced aggregation behaviors compared to classic\nactive Brownian particles, especially at lower particle densities and larger\nrotational diffusivities. Importantly, in contrast to the classic ABP system,\nthe high-density phase of APPA system exhibits strong dynamic correlation,\nwhich is characterized by the slowly decaying velocity correlation functions\nwith a correlation length comparable to the linear size of high-density phase\ndomain (i.e., cluster of the particles). The strongly correlated multi-cellular\ndynamics predicted by the APPA model are subsequently verified in {\\it in\nvitro} experiments using MCF-10A cells. Our studies also indicate the\nimportance of incorporating ECM-mediated mechanical coupling among the\nmigrating cells for appropriately modeling emergent multi-cellular dynamics in\ncomplex micro-environments."
    },
    {
        "anchor": "On the analogy between the restricted primitive model and capacitor\n  circuits. Part II: A generalized Gibbs-Duhem consistent extension of the\n  Pitzer-Debye-H\u00fcckel term with corrections for low and variable relative\n  permittivity: We present a novel, thermodynamically consistent modification of the\nPitzer-Debye-H\\\"uckel term and its extension for concentration dependent\ndensity, molar mass and relative permittivity. This extension is validated for\nionic liquids by comparison with a reference model from the literature and, in\ncontrast to similar extensions, also applied to conventional salts with small\nspherical ions in aqueous, mixed and non-aqueous solvents. The central novelty\nis the inclusion of a modified parameter of closest approach, which improves\nthe overall qualitative performance of the Pitzer-Debye-H\\\"uckel term over the\ncomplete relative permittivity range. Gibbs-Duhem consistency is retained in\nthe modified extension and sample calculations for aqueous [BMIM][BF4] and\naqueous NaCl are provided. The novel, modified and extended term with\nconcentration dependent properties is combined with the predictive COSMO-RS-ES\nmodel for the calculation of phase equilibria and activity coefficients in\nelectrolytes with conventional salts. The performance of the COSMO-RS-ES model\nfor predictions of salt solubility in fully non-aqueous media improves\nsignificantly upon introduction of concentration dependent properties within\nthe long-range electrostatics. Modelling performance with the modified extended\nPitzer-Debye-H\\\"uckel term outperforms modelling with the unmodified extension\nas well as with the conventional term with no extension. The correlated\nrelative permittivity of the mixture is overestimated with respect to\nexperimental values and kinetic depolarization effects provide a plausible\nexplanation for this observation. Overall, our results support the consistent\nintroduction of concentration dependent properties within the electrostatic\ntheory in order to improve the modelling of electrolytes with particular\nemphasis on non-aqueous electrolytes.",
        "positive": "Effects of chain length on Rouse modes and non-Gaussianity in linear and\n  ring polymer melts: The dynamics of ring polymer melts are studied via molecular dynamics\nsimulations of the Kremer-Grest bead-spring model. Rouse mode analysis is\nperformed in comparison with linear polymers by changing the chain length.\nRouse-like behavior is observed in ring polymers by quantifying the chain\nlength dependence of the Rouse relaxation time, whereas a crossover from Rouse\nto reptation behavior is observed in linear polymers. Furthermore, the\nnon-Gaussian parameters of the monomer bead displacement and chain\ncenter-of-mass displacement are analyzed. It is found that the non-Gaussianity\nof ring polymers is remarkably suppressed with slight growth for the\ncenter-of-mass dynamics at long chain length, which is in contrast to the\ngrowth in linear polymers both for the monomer bead and center-of-mass\ndynamics."
    },
    {
        "anchor": "Chemical potential of a test hard sphere of variable size in a\n  hard-sphere fluid: The Lab\\'ik and Smith Monte Carlo simulation technique to implement the Widom\nparticle insertion method is applied using Molecular Dynamics (MD) instead to\ncalculate numerically the insertion probability, $P_0(\\eta,\\sigma_0)$, of\ntracer hard-sphere (HS) particles of different diameters, $\\sigma_0$, in a host\nHS fluid of diameter $\\sigma$ and packing fraction, $\\eta$, up to $0.5$. It is\nshown analytically that the only polynomial representation of $-\\ln\nP_0(\\eta,\\sigma_0)$ consistent with the limits $\\sigma_0\\to 0$ and\n$\\sigma_0\\to\\infty$ has necessarily a cubic form,\n$c_0(\\eta)+c_1(\\eta)\\sigma_0/\\sigma+c_2(\\eta)(\\sigma_0/\\sigma)^2+c_3(\\eta)(\\sigma_0/\\sigma)^3$.\nOur MD data for $-\\ln P_0(\\eta,\\sigma_0)$ are fitted to such a cubic polynomial\nand the functions $c_0(\\eta)$ and $c_1(\\eta)$ are found to be statistically\nindistinguishable from their exact solution forms. Similarly, $c_2(\\eta)$ and\n$c_3(\\eta)$ agree very well with the\nBoubl\\'ik-Mansoori-Carnahan-Starling-Leland and\nBoubl\\'ik-Carnahan-Starling-Kolafa formulas. The cubic polynomial is\nextrapolated (high density) or interpolated (low density) to obtain the\nchemical potential of the host fluid, or $\\sigma_{0}\\to\\sigma$, as\n$\\beta\\mu^{\\text{ex}}=c_0+c_1+c_2+c_3$. Excellent agreement between the\nCarnahan-Starling and Carnahan-Starling-Kolafa theories with our MD data is\nevident.",
        "positive": "Biphasic, Lyotropic, Active Nematics: We perform dynamical simulations of a two-dimensional active nematic fluid in\ncoexistence with an isotropic fluid. Drops of active nematic become elongated,\nand an effective anchoring develops at the nematic-isotropic interface. The\nactivity also causes an undulatory instability of the interface. This results\nin defects of positive topological charge being ejected into the nematic,\nleaving the interface with a diffuse negative charge. Quenching the active\nlyotropic fluid results in a steady state in which phase-separating domains are\nelongated and then torn apart by active stirring."
    },
    {
        "anchor": "Unusual Phase Behavior of Confined Heavy Water: Many of the anomalous properties of water are amplified in the deeply\nsupercooled region. Here we present neutron scattering measurements of the\ndensity of heavy water confined in a nanoporous silica matrix MCM-41-S\n(\\approx15 {\\AA} pore diameter), namely, the equation of state {\\rho}(T,P), in\na temperature-pressure range, from 300 K to 130 K and from 1 bar to 2900 bar,\nwhere bulk water will crystalize. A sudden change of slope in the otherwise\ncontinuous density profile (a \"kink\") is observed below a certain pressure Pc;\nhowever, this feature is absent above Pc. Instead, a hysteresis phenomenon in\nthe density profiles between the warming and cooling scans becomes prominent\nabove Pc. Hence, the data can be interpreted as a line of apparent 2nd-order\nphase transition at low pressures evolving into a line of 1st-order phase\ntransition at high pressures. If so, the existence of a \"tricritical point\" at\nPc \\approx 1500 bar, Tc \\approx 210 K becomes another possible scenario to\nexplain the exceptionally rich phase behavior of low-temperature confined\nwater.",
        "positive": "Pattern formation and glassy phase in the $\u03c6^4$ theory with screened\n  electrostatic repulsion: We study analytically the structural properties of a system with a\nshort-range attraction and a competing long-range screened repulsion. This\nmodel contains the essential features of the effective interaction potential\namong charged colloids in polymeric solutions and provides novel insights on\nthe equilibrium phase diagram of these systems. Within the self-consistent\nHartree approximation and by using a replica approach, we show that varying the\nparameters of the repulsive potential and the temperature yields a phase\ncoexistence, a lamellar and a glassy phase. Our results strongly suggest that\nthe cluster phase observed in charged colloids might be the signature of an\nunderlying equilibrium lamellar phase, hidden on experimental time scales."
    },
    {
        "anchor": "Two-Dimensional Fluctuating Vesicles in Linear Shear Flow: The stochastic motion of a two-dimensional vesicle in linear shear flow is\nstudied at finite temperature. In the limit of small deformations from a\ncircle, Langevin-type equations of motion are derived, which are highly\nnonlinear due to the constraint of constant perimeter length. These equations\nare solved in the low temperature limit and using a mean field approach, in\nwhich the length constraint is satisfied only on average. The constraint\nimposes non-trivial correlations between the lowest deformation modes at low\ntemperature. We also simulate a vesicle in a hydrodynamic solvent by using the\nmulti-particle collision dynamics technique, both in the quasi-circular regime\nand for larger deformations, and compare the stationary deformation correlation\nfunctions and the time autocorrelation functions with theoretical predictions.\nGood agreement between theory and simulations is obtained.",
        "positive": "Dimensional crossover of the fundamental-measure functional for parallel\n  hard cubes: We present a regularization of the recently proposed fundamental-measure\nfunctional for a mixture of parallel hard cubes. The regularized functional is\nshown to have right dimensional crossovers to any smaller dimension, thus\nallowing to use it to study highly inhomogeneous phases (such as the solid\nphase). Furthermore, it is shown how the functional of the slightly more\ngeneral model of parallel hard parallelepipeds can be obtained using the\nzero-dimensional functional as a generating functional. The multicomponent\nversion of the latter system is also given, and it is suggested how to\nreformulate it as a restricted-orientation model for liquid crystals. Finally,\nthe method is further extended to build a functional for a mixture of parallel\nhard cylinders."
    },
    {
        "anchor": "Spreading of foam on a substrate: Foam is an industrially important form of matter, commonly deployed to clean\nobjects and even our own skin, thanks to its ability to absorb oil and\nparticles into its interior. To clean a large area, a foam is spread over a\nsubstrate, but the optimum conditions and mechanism have been unclear. Here, we\nstudy how a foam is spread by a rigid plate on a substrate as a function of\nspreading velocity, gap height, confinement length, amount of foam and\nwettability of the substrate. Three distinguishable spreading patterns were\nfound: homogeneous spreading, non-spreading, and slender spreading. It is also\nfound that the dynamics and the mechanism of the spreading can be explained by\ncoupling among dewetting, anchoring, shear stress, viscous stress and yield\nstress. It is a unique feature of foams, which is not observed in simple\nliquids and then these findings are also critical for understanding the\nmechanical response of other soft jamming systems such as cells and emulsions.",
        "positive": "Morphology-dependent random binary fragmentation of in silico\n  fractal-like agglomerates: Linear binary fragmentation of synthetic fractal-like agglomerates composed\nof spherical, equal-size, touching monomers is numerically investigated.\nAgglomerates of different morphologies are fragmented via random bond removal.\nThe fragmentation algorithm relies on mapping each agglomerate onto an\nadjacency matrix. The numerically-determined fragment size distributions are\nU-shaped, clusters break predominantly into two largely dissimilar fragments,\nbecoming more uniform as the fractal dimension decreases. A symmetric beta\ndistribution reproduces the fragment distribution rather accurately. Its\nexponent depends on the structure (fractal dimension) and number of monomers of\nthe initial agglomerate. A universal fragment distribution, a function only of\nthe initial fractal dimension, is derived by requiring that it satisfy the\nfragmentation conversation laws and the straight-chain limit. We argue that the\nfragmentation rate is proportional to the initial agglomerate size."
    },
    {
        "anchor": "Hydration free energies of polypeptides from popular implicit solvent\n  models versus all-atom simulation results based on molecular quasichemical\n  theory: The hydration free energy of a macromolecule is the central property of\ninterest for understanding its distribution over conformations and its state of\naggregation. Calculating the hydration free energy of a macromolecule in\nall-atom simulations has long remained a challenge, necessitating the use of\nmodels wherein the effect of the solvent is captured without explicit account\nof solvent degrees of freedom. This situation has changed with developments in\nthe molecular quasi-chemical theory (QCT), an approach that enables calculation\nof the hydration free energy of macromolecules within all-atom simulations at\nthe same resolution as is possible for small molecule solutes. The theory also\nprovides a rigorous and physically transparent framework to conceptualize and\nmodel interactions in molecular solutions, and thus provides a convenient\nframework to investigate the assumptions in implicit-solvent models. In this\nstudy, we compare the results using molecular QCT versus predictions from EEF1,\nABSINTH, and GB/SA implicit-solvent models for poly-glycine and poly-alanine\nsolutes covering a range of chain lengths and conformations. Among the three\nmodels, GB/SA does best in capturing the broad trends in hydration free energy.\nWe trace the deficiencies of the group-additive EEF1 and ABSINTH models to\ntheir under-appreciation of the cooperativity of hydration between solute\ngroups; seen in this light, the better performance of GB/SA can be attributed\nto its treatment of the collective properties of hydration, albeit within a\ncontinuum dielectric framework. We highlight the importance of validating the\nindividual physical components that enter implicit solvent models for protein\nsolution thermodynamics.",
        "positive": "Roughness-induced friction in liquid foams: Complex liquids flow is known to be drastically affected by the roughness\ncondition at the interfaces. We combined stresses measurements and observations\nof the flow during the motion of different rough surfaces in dry liquid foams.\nWe visually show that three distinct friction regimes exists: slippage,\nstick-slip motion, and anchored soap films. Our stress measurements are\nvalidated for slippage and anchored regimes based on existing models, and we\npropose a leverage rule to describe the stresses during the stick-slip regime.\nWe find that the occurrence of the stick-slip or anchored regimes is controlled\nby the roughness factor, defined as the ratio between the size of the surface\nasperities and the radius of curvature of the Plateau borders."
    },
    {
        "anchor": "In-situ Characterization of Crystallization and Melting of Soft,\n  Thermoresponsive Microgels by Small-Angle X-ray Scattering: Depending on the volume fraction and interparticle interactions, colloidal\nsuspensions can form different phases, ranging from fluids, crystals, and\nglasses to gels. For soft microgels that are made from thermoresponsive\npolymers, the volume fraction can be tuned by temperature, making them\nexcellent systems to experimentally study phase transitions in dense colloidal\nsuspensions. However, investigations of phase transitions at high particle\nconcentration and across the volume phase transition temperature in particular,\nare challenging due to the deformability and possibility for interpenetration\nbetween microgels. Here, we investigate the dense phases of composite\ncore-shell microgels that have a small gold core and a thermoresponsive\nmicrogel shell. Employing Ultra Small Angle X-ray Scattering, we make use of\nthe strong scattering signal from the gold cores with respect to the almost\nnegligible signal from the shells. By changing the temperature we study the\nfreezing and melting transitions of the system in-situ. Using Bragg peak\nanalysis and the Williamson-Hall method, we characterize the phase transitions\nin detail. We show that the system crystallizes into an rhcp structure with\ndifferent degrees of in-plane and out-of-plane stacking disorder that increase\nupon particle swelling. We further find that the melting process is distinctly\ndifferent, where the system separates into two different crystal phases with\ndifferent melting temperatures and interparticle interactions.",
        "positive": "Enhancement of bubble transport in porous electrodes and catalysts: We investigate the formation and transport of gas bubbles across a model\nporous catalyst/electrode using lattice Boltzmann simulations. This approach\nenables us to systematically examine the influence of a wide range of\nmorphologies, flow velocities, and reaction rates on the efficiency of gas\nproduction. By exploring these parameters, we identify critical parameter\ncombinations that significantly contribute to an enhanced yield of gas output.\nOur simulations reveal the existence of an optimal pore geometry for which the\nproduct output is maximized. Intriguingly, we also observe that lower flow\nvelocities improve gas production by leveraging on coalescence-induced bubble\ndetachment from the catalyst."
    },
    {
        "anchor": "Micro-evaporators for kinetic exploration of phase diagrams: We use pervaporation-based microfluidic devices to concentrate species in\naqueous solutions with spatial and temporal control of the process. Using\nexperiments and modelling, we quantitatively describe the advection-diffusion\nbehavior of the concentration field of various solutions (electrolytes,\ncolloids, etc) and demonstrate the potential of these devices as universal\ntools for the kinetic exploration of the phases and textures that form upon\nconcentration.",
        "positive": "Like-charge colloidal attraction: a simple argument: By a length scale analysis, we study the equilibrium interactions between two\nlike-charge planes confining neutralising counter-ions. At large Coulombic\ncouplings, approaching the two charged bodies leads to an unbinding of\ncounter-ions, a situation that is amenable to an exact treatment. This\nphenomenon is the key to attractive effective interactions. A particular effort\nis made for pedagogy, keeping equations and formalism to a minimum."
    },
    {
        "anchor": "Direct links between dynamical, thermodynamic and structural properties\n  of liquids: modelling results: We develop an approach to liquid thermodynamics based on collective modes. We\nperform extensive molecular dynamics simulations of noble, molecular and\nmetallic liquids and provide the direct evidence that liquid energy and\nspecific heat are well-described by the temperature dependence of the Frenkel\n(hopping) frequency. The agreement between predicted and calculated\nthermodynamic properties is seen in the notably wide range of temperature\nspanning tens of thousands of Kelvin. The range includes both subcritical\nliquids and supercritical fluids. We discuss the structural crossover and\ninter-relationships between structure, dynamics and thermodynamics of liquids\nand supercritical fluids.",
        "positive": "Computational modeling of tactoid dynamics in chromonic liquid crystals: Motivated by recent experiments, the isotropic-nematic phase transition in\nchromonic liquid crystals is studied. As temperature decreases, nematic nuclei\nnucleate, grow, and coalesce, giving rise to tactoid microstructures in an\nisotropic liquid. These tactoids produce topological defects at domain\njunctions (disclinations in the bulk or point defects on the surface). We\nsimulate such tactoid equilibria and their coarsening dynamics with a model\nusing degree of order, a variable length director, and an interfacial normal as\nstate descriptors. We adopt Ericksen's work and introduce an augmented\nOseen-Frank energy, with non-convexity in both interfacial energy and the\ndependence of the energy on the degree of order. A gradient flow dynamics of\nthis energy does not succeed in reproducing some simple expected feature of\ntactoid dynamics. Therefore, a strategy is devised based on continuum\nkinematics and thermodynamics to represent such features. The model is used to\npredict tactoid nucleation, expansion, and coalescence during the process of\nphase transition. We reproduce observed behaviors in experiments and perform an\nexperimentally testable parametric study of the effect of bulk elastic and\ntactoid interfacial energy parameters on the interaction of interfacial and\nbulk fields in the tactoids."
    },
    {
        "anchor": "Influence of polydispersity on the relaxation mechanisms of glassy\n  liquids: State-of-the-art techniques for simulating deeply supercooled liquids require\na high degree of size polydispersity to be effective. While these techniques\nhave enabled great insight into the microscopic dynamics near the glass\ntransition, the effect of the large polydispersity on the dynamics has remained\nlargely unstudied. Here we show that a particle's size not only has a strong\ncorrelation with its mobility, but we also observe that, as the mode-coupling\ntemperature is crossed and the system becomes more deeply supercooled, a\ndynamic separation between small mobile and larger quiescent particles emerges\nat timescales corresponding to cage escape. Our results suggest that the cage\nescape of this population of mobile particles facilitates the later structural\nrelaxation of the quiescent particles. In the deep supercooled regime, we show\nthat particles of different sizes display varying degrees of breakdown of the\nStokes-Einstein relation and have different activation energy barriers.\nOverall, this indicates that it is important to account for particle-size\neffects when generalizing results to other glass-forming systems.",
        "positive": "Dynamics of Deformable Active Particles under External Flow Field: In most practical situations, active particles are affected by their\nenvironment, for example, by a chemical concentration gradient, light\nintensity, gravity, or confinement. In particular, the effect of an external\nflow field is important for particles swimming in a solvent fluid. For\ndeformable active particles such as self-propelled liquid droplets and active\nvesicles, as well as microorganisms such as euglenas and neutrophils, a general\ndescription has been developed by focusing on shape deformation. In this\nreview, we present our recent studies concerning the dynamics of a single\nactive deformable particle under an external flow field. First, a set of model\nequations of active deformable particles including the effect of a general\nexternal flow is introduced. Then, the dynamics under two specific flow\nprofiles is discussed: a linear shear flow, as the simplest example, and a\nswirl flow. In the latter case, the scattering dynamics of the active\ndeformable particles by the swirl flow is also considered."
    },
    {
        "anchor": "Nonlinear electrophoresis of dielectric and metal spheres in a nematic\n  liquid crystal: Electrophoresis is a motion of charged dispersed particles relative to a\nfluid in a uniform electric field. The effect is widely used to separate\nmacromolecules, to assemble colloidal structures, to transport particles in\nnano- and micro-fluidic devices and displays. Typically, the fluid is isotropic\n(for example, water) and the electrophoretic velocity is linearly proportional\nto the electric field. In linear electrophoresis, only a direct current (DC)\nfield can drive the particles. An alternate current (AC) field is more\ndesirable because it allows one to overcome problems such as electrolysis and\nabsence of steady flows. Here we show that when the electrophoresis is\nperformed in a nematic fluid, the effect becomes strongly non-linear with a\nvelocity component that is quadratic in the applied voltage and has a direction\nthat generally differs from the direction of linear velocity. The new\nphenomenon is caused by distortions of the LC orientation around the particle\nthat break the fore-aft (or left-right) symmetry. The effect allows one to\ntransport both charged and neutral particles, even when the particles\nthemselves are perfectly symmetric (spherical), thus enabling new approaches in\ndisplay technologies, colloidal assembly, separation, microfluidic and\nmicromotor applications.",
        "positive": "Topological packing statistics distinguish living and non-living matter: How much structural information is needed to distinguish living from\nnon-living systems? Here, we show that the statistical properties of Delaunay\ntessellations suffice to differentiate prokaryotic and eukaroytic cell packings\nfrom a wide variety of inanimate physical structures. By introducing a\nmathematical framework for measuring topological distances between general 3D\npoint clouds, we construct a universal topological atlas encompassing bacterial\nbiofilms, snowflake yeast, plant shoots, zebrafish brain matter, organoids, and\nembryonic tissues as well as foams, colloidal packings, glassy materials, and\nstellar configurations. Living systems are found to localize within a bounded\nisland-like region, reflecting that growth memory essentially distinguishes\nmulticellular from physical packings. By detecting subtle topological\ndifferences, the underlying metric framework enables a unifying classification\nof 3D disordered media, from microbial populations, organoids and tissues to\namorphous materials and astrophysical systems."
    },
    {
        "anchor": "Clustering and Micro-immiscibility in Alcohol-Water Mixtures: Evidence\n  from Molecular Dynamics Simulations: We have investigated the hydrogen-bonded structures in liquid methanol and a\n7:3 mole fraction aqueous solution using classical Molecular Dynamics\nsimulations at 298K and ambient pressure. We find that, in contrast to recent\npredictions from X-ray emission studies, the hydrogen-bonded structure in\nliquid methanol is dominated by chain and small ring structures. In the\nmethanol-rich solution, we find evidence of micro-immiscibility, supporting\nrecent conclusions derived from neutron diffraction data.",
        "positive": "A formula for the minimal coordination number of a parallel bundle: An exact formula for the minimal coordination numbers of the parallel packed\nbundle of rods is presented based on an optimal thickening scenario. Hexagonal\nand square lattices are considered."
    },
    {
        "anchor": "Aging and Levy distributions in sandpiles: Aging in complex systems is studied via the sandpile model. Relaxation of\navalanches in sandpiles is observed to depend on the time elapsed since the\nbegining of the relaxation. Levy behavior is observed in the distribution of\ncharacteristic times. In this way, aging and self-organized criticality appear\nto be closely related.",
        "positive": "Ion-induced nucleation in polar one-component fluids: We present a Ginzburg-Landau theory of ion-induced nucleation in a gas phase\nof polar one-component fluids, where a liquid droplet grows with an ion at its\ncenter. By calculating the density profile around an ion, we show that the\nsolvation free energy is larger in gas than in liquid at the same temperature\non the coexistence curve. This difference much reduces the nucleation barrier\nin a metastable gas."
    },
    {
        "anchor": "Cooperative wrapping of nanoparticles by membrane tubes: The bioactivity of nanoparticles crucially depends on their ability to cross\nbiomembranes. Recent simulations indicate the cooperative wrapping and\ninternalization of spherical nanoparticles in tubular membrane structures. In\nthis article, we systematically investigate the energy gain of this cooperative\nwrapping by minimizing the energies of the rotationally symmetric shapes of the\nmembrane tubes and of membrane segments wrapping single particles. We find that\nthe energy gain for the cooperative wrapping of nanoparticles in membrane tubes\nrelative to their individual wrapping as single particles strongly depends on\nthe ratio of the particle radius and the range of the particle-membrane\nadhesion potential. For a potential range of the order of one nanometer, the\ncooperative wrapping in tubes is highly favorable for particles with a radius\nof tens of nanometers and intermediate adhesion energies, but not for particles\nthat are significantly larger.",
        "positive": "Lattice Boltzmann study on Kelvin-Helmholtz instability: the roles of\n  velocity and density gradients: A two-dimensional lattice Boltzmann model with 19 discrete velocities for\ncompressible Euler equations is proposed (D2V19-LBM). The fifth-order Weighted\nEssentially Non-Oscillatory (5th-WENO) finite difference scheme is employed to\ncalculate the convection term of the lattice Boltzmann equation. The validity\nof the model is verified by comparing simulation results of the Sod shock tube\nwith its corresponding analytical solutions. The velocity and density gradient\neffects on the Kelvin-Helmholtz instability (KHI) are investigated using the\nproposed model. Sharp density contours are obtained in our simulations. It is\nfound that, the linear growth rate $\\gamma$ for the KHI decreases with\nincreasing the width of velocity transition layer ${D_{v}}$ but increases with\nincreasing the width of density transition layer ${D_{\\rho}}$. After the\ninitial transient period and before the vortex has been well formed, the linear\ngrowth rates, $\\gamma_v$ and $\\gamma_{\\rho}$, vary with ${D_{v}}$ and\n${D_{\\rho}}$ approximately in the following way, $\\ln\\gamma_{v}=a-bD_{v}$ and\n$\\gamma_{\\rho}=c+e\\ln D_{\\rho} ({D_{\\rho}}<{D_{\\rho}^{E}})$, where $a$, $b$,\n$c$ and $e$ are fitting parameters and ${D_{\\rho}^{E}}$ is the effective\ninteraction width of density transition layer. When ${D_{\\rho}}>{D_{\\rho}^{E}}$\nthe linear growth rate $\\gamma_{\\rho}$ does not vary significantly any more.\nOne can use the hybrid effects of velocity and density transition layers to\nstabilize the KHI. Our numerical simulation results are in general agreement\nwith the analytical results [L. F. Wang, \\emph{et al.}, Phys. Plasma\n\\textbf{17}, 042103 (2010)]."
    },
    {
        "anchor": "Effects of strongly selective additives on volume phase transition in\n  gels: We investigate volume phase transition in gels immersed in mixture solvents,\non the basis of a three-component Flory-Rehner theory. When the selectivity of\nthe minority solvent component to the polymer network is strong, the gel tends\nto shrink with an increasing concentration of the additive, regardless of\nwhether it is good or poor. This behavior originates from the difference of the\nadditive concentration between inside and outside the gel. We also found the\ngap of the gel volume at the transition point can be controlled by adding the\nstrongly selective solutes. By dissolving a strongly poor additive, for\ninstance, the discontinuous volume phase transition can be extinguished.\nFurthermore, we observed that another volume phase trasition occurs far from\nthe original transition point. These behaviors can be well explained by a\nsimplified theory neglecting the non-linearity of the additive concentration.",
        "positive": "Monte Carlo study of shear-induced alignment of cylindrical micelles in\n  thin films: The behavior of confined cylindrical micelle-forming surfactants under the\ninfluence of shear has been investigated using Monte Carlo simulations. The\nsurfactants are modeled as coarse-grained lattice polymers, while the Monte\nCarlo shear flow is implemented with an externally imposed potential energy\nfield which induces a linear drag velocity on the surfactants. It is shown that\nin the absence of shear, cylindrical micelles confined within a monolayer\ncoarsen gradually with Monte Carlo \"time\" t, the persistence length of the\nmicelles scaling as t^{0.24}, in agreement with the scaling obtained\nexperimentally. Under the imposition of shear, the micelles within a monolayer\nalign parallel to the direction of shear, as observed experimentally. Micelles\nconfined within thicker films also align parallel to each other with a\nhexagonal packing under shear, but assume a finite tilt with respect to the\nvelocity vector within the velocity-velocity gradient plane. We propose a novel\nmechanism for this shear-induced alignment of micelles based on breaking up of\nmicelles aligned perpendicular to shear and their reformation and subsequent\ngrowth in the shear direction. It is observed that there exists a \"window\" of\nshear rates within which such alignment occurs. A phenomenological theory\nproposed to explain the above behavior is in good agreement with simulation\nresults. A comparison of simulated and experimental self-diffusivities yields a\nphysical timescale for Monte Carlo moves, which enables an assessment of the\nphysical shear rates employed in our Monte Carlo simulations."
    },
    {
        "anchor": "Kinetics of island growth in the framework of planar diffusion zones and\n  3D nucleation and growth models for electrodeposition: In the electrochemical deposition of thin films the measurement of the\ncurrent-time curve does not allow for a direct determination of the nucleus\ngrowth law, electrode surface coverage and mean film thickness. In this work we\npresent a theoretical approach suitable to gain insight into these quantities\nfrom the knowledge of nucleation density, solution parameters and current-time\nbehavior. The model applies to both isotropic and anisotropic growth rates of\nnuclei and a study on the effect of nucleus shape and aspect ratio on the\nkinetics is presented. Experimental results from literature are also discussed\nin the framework of the present approach.",
        "positive": "Swimming droplet in 1D geometries, an active Bretherton problem: We investigate experimentally the behavior of self-propelled water-in-oil\ndroplets, confined in capillaries of different square and circular\ncross-sections. The droplet's activity comes from the formation of swollen\nmicelles at its interface. In straight capillaries the velocity of the droplet\ndecreases with increasing confinement. However at very high confinement, the\nvelocity converges toward a non-zero value, so that even very long droplets\nswim. Stretched circular capillaries are then used to explore even higher\nconfinement. The lubrication layer around the droplet then takes a non-uniform\nthickness which constitutes a significant difference with usual flow-driven\npassive droplets. A neck forms at the rear of the droplet, deepens with\nincreasing confinement, and eventually undergoes successive spontaneous\nsplitting events for large enough confinement. Such observations stress the\ncritical role of the activity of the droplet interface on the droplet's\nbehavior under confinement. We then propose an analytical formulation by\nintegrating the interface activity and the swollen micelles transport problem\ninto the classical Bretherton approach. The model accounts for the convergence\nof the droplet's velocity to a finite value for large confinement, and for the\nnon-classical shape of the lubrication layer. We further discuss on the\nsaturation of the micelles concentration along the interface, which would\nexplain the divergence of the lubrication layer thickness for long enough\ndroplets, eventually leading to the spontaneous droplet division."
    },
    {
        "anchor": "Moulding hydrodynamic 2D-crystals upon parametric Faraday waves in\n  shear-functionalized water surfaces: Faraday waves (FWs), or surface waves oscillating at half of the natural\nfrequency when a liquid is vertically vibrated, are archetypes of ordering\ntransitions on liquid surfaces. The existence of unbounded FW-patterns\nsustained upon bulk frictional stresses has been evidenced in highly viscous\nfluids. However, the role of surface rigidity has not been investigated so far.\nHere, we demonstrate that dynamically frozen FWs that we call 2D-hydrodynamic\ncrystals do appear as ordered patterns of nonlinear surface modes in water\nsurfaces functionalized with soluble (bio)surfactants endowing in-plane shear\nstiffness. The strong phase coherence in conjunction with the increased surface\nrigidity bear the FW-ordering transition, upon which the hydrodynamic crystals\nwere reversibly molded by parametric control of their degree of order. Crystal\nsymmetry and unit cell size were tuned depending on the FW-dispersion regime.\nThe hydrodynamic crystals here discovered could be exploited in touchless\nstrategies of soft matter scaffolding. Particularly, the surface-directed\nsynthesis of structured materials based on colloids or polymers and cell\nculture patterns for tissue engineering could be ameliorated under external\ncontrol of FW-coherence",
        "positive": "Chaotic and periodical dynamics of active chiral droplets: The interplay between the chirality of many biological molecules and the\nenergy injected at small length-scales as the result of biological processes is\nat the base of the life of the cells. With the aim of unveiling the connection\nbetween these two features, here we analyze by means of lattice Boltzmann\nsimulations the behavior of an active droplet of cholesteric liquid crystal\nunder the effect of intense active doping, within the framework of active gel\ntheory. We find that a droplet of chiral liquid crystal, fueled by active force\ndipoles, develops defect loops (closed disclination lines) that pierce the\ninterior of the droplet, leading the droplet to develop an erratic motility\nmode. When the droplet is fueled by in-warding active torque dipoles, three\ndifferent dynamical regimes develops at varying both the thermodynamic\nchirality and the strength of active energy injection: a stable rotational\nstate at low activity, an intermittent disclination dance regime, and a\nturbulent state where closed disclination lines formation is inhibited and new\npairs of oppositely charged surface defects leads to the development of chaotic\nrotational motion. Finally, we show that out-warding torque dipoles are able to\nsustain a periodical dynamics at higher chirality characterized by the\nnucleation/annihilation of pairs of disclination rings."
    },
    {
        "anchor": "Ubiquitous preferential water adsorption to electrodes in\n  water/1-propanol mixtures detected by electrochemical impedance spectroscopy: The electric double layer is an important structure that appears at charged\nliquid interfaces, and it determines the performance of various electrochemical\ndevices such as supercapacitors and electrokinetic energy converters. Here the\ndouble-layer capacitance of the interface between aluminum electrodes and\nwater/1-propanol electrolyte solutions is investigated using electrochemical\nimpedance spectroscopy. The double-layer capacitances of mixture solvents are\nalmost the same as those of water-only electrolyte solutions, and the\ndouble-layer capacitance of 1-propanol-only solutions are significantly smaller\nthan those of other volume fractions of water. The qualitative variation of the\ndouble-layer capacitances with the water volume fraction is independent of the\nelectrolyte types and their concentrations. Therefore, these results can be\nexplained by ubiquitous preferential water adsorption caused by the\nhydrophilicity of the electrode surface.",
        "positive": "Spinodal decomposition in polymer mixtures via surface diffusion: We present experimental results for spinodal decomposition in polymer\nmixtures of gelatin and dextran. The domain growth law is found to be\nconsistent with t^1/4-growth over extended time-regimes. Similar results are\nobtained from lattice simulations of a polymer mixture. This slow growth arises\ndue to the suppression of the bulk mobility of polymers. In that case, spinodal\ndecomposition is driven by the diffusive transport of material along domain\ninterfaces, which gives rise to a t^1/4-growth law."
    },
    {
        "anchor": "Effects of macromolecular crowding on the collapse of biopolymers: Experiments show that macromolecular crowding modestly reduces the size of\nintrinsically disordered proteins (IDPs) even at volume fraction ($\\phi$)\nsimilar to that in the cytosol whereas DNA undergoes a coil-to-globule\ntransition at very small $\\phi$. We show using a combination of scaling\narguments and simulations that the polymer size $\\overline{R}_g(\\phi)$ depends\non $x = \\overline{R}_g(0)/D$ where $D$ is the $\\phi$-dependent distance between\nthe crowders. If $x\\lesssim \\mathcal{O}(1)$, there is only a small decrease in\n$\\overline{R}_g(\\phi)$ as $\\phi$ increases. When $x\\gg \\mathcal{O}(1)$, a\ncooperative coil-to-globule transition is induced. Our theory quantitatively\nexplains a number of experiments.",
        "positive": "Confined subdiffusion in three dimensions: The three-dimensional (3D) Fick's diffusion equation and fractional diffusion\nequation are solved for different reflecting boundaries. We use the continuous\ntime random walk model (CTRW) to investigate the time averaged mean square\ndisplacement (MSD) of 3D single particle trajectory. Theoretical results show\nthe ensemble average of the time averaged MSD can be expressed analytically by\na Mittag-Leffler function. Our new expression is in agreement with previous\nformulas in two limiting cases which are $ < \\overline{\\delta^2} > \\sim\\Delta $\nin short lag time and $ < \\overline{\\delta^2}> \\sim\\Delta^{1-\\alpha}$ in long\nlag time. We also simulate the experimental data of mRNA diffusion in living E.\ncoli using 3D CTRW model under confined and crowded conditions. The simulated\nresults are well consistent with experimental results. The calculations of\npower spectral density (PSD) indicate further the subdiffsive behavior of\nindividual trajectory."
    },
    {
        "anchor": "Linking the dielectric Debye process in 2-ethyl-1-hexanol to its density\n  fluctuations: We provide the first evidence that the puzzling dielectric Debye process\nobserved in mono-alcohols is coupled to density fluctuations. The results open\nup for an explanation of the Debye process within the framework of conventional\nliquid-state theory. The spectral shape of dynamical bulk modulus of\n2-ethyl-1-hexanol is nearly identical to that of the shear modulus, and thus\nthe supramolecular structures believed to be responsible for the slow\ndielectric Debye process are manifested in the bulk modulus in the same way as\nin the shear modulus.",
        "positive": "Finsler geometry modeling of phase separation in multi-component\n  membranes: Finsler geometric surface model is studied as a coarse-grained model for\nmembranes of three-component such as DOPC, DPPC and Cholesterol. To understand\nthe phase separation of liquid ordered (DPPC rich) $L_o$ and the liquid\ndisordered (DOPC rich) $L_d$, we introduce a variable $\\sigma (\\in \\{1,-1\\})$\nin the triangulated surface model. We numerically find that there appear two\ncirculars and stripe domains on the surface and that these two morphologies are\nseparated by a phase transition. The morphological change from the one to the\nother with respect to the variation of the area fraction of $L_o$ is consistent\nwith existing experimental results. This gives us a clear understanding of the\norigin of the line tension energy, which has been used to understand those\nmorphological changes in the three-component membranes. In addition to these\ntwo circulars and stripe domains, raft-like domain and budding domain are also\nobserved, and the corresponding several phase diagrams are obtained. Technical\ndetails of the Finsler geometry modeling are also shown."
    },
    {
        "anchor": "Thermodynamic and kinetic fragility of Freon113: the most fragile\n  plastic crystal: We present a dynamic and thermodynamic study of the orientational glass\nformer Freon113 (CCl2F-CClF2) in order to analyze its kinetic and thermodynamic\nfragilities. Freon113 displays internal molecular degrees of freedom which\npromote a complex energy landscape. Experimental specific heat and its\nmicroscopic origin, the vibrational density of states from inelastic neutron\nscattering, together with the orientational dynamics obtained by means of\ndielectric spectroscopy have revealed the highest fragility value, both\nthermodynamic and kinetic, found for this orientational glass former. The\nexcess in both Debye-reduced specific heat and density of states (boson peak)\nevidences the existence of glassy low-energy excitations. We demonstrate that\nearly proposed correlations between the boson peak and the Debye specific heat\nvalue are elusive as revealed by the clear counterexample of the studied case.",
        "positive": "Self-propelled particles with selective attraction-repulsion interaction\n  - From microscopic dynamics to coarse-grained theories: In this work we derive and analyze coarse-grained descriptions of\nself-propelled particles with selective attraction-repulsion interaction, where\nindividuals may respond differently to their neighbours depending on their\nrelative state of motion (approach versus movement away). Based on the\nformulation of a nonlinear Fokker-Planck equation, we derive a kinetic\ndescription of the system dynamics in terms of equations for the Fourier modes\nof a one-particle density function. This approach allows effective numerical\ninvestigation of the stability of possible solutions of the system. The\ndetailed analysis of the interaction integrals entering the equations\ndemonstrates that divergences at small wavelengths can appear at arbitrary\nexpansion orders.\n  Further on, we also derive a hydrodynamic theory by performing a closure at\nthe level of the second Fourier mode of the one-particle density function. We\nshow that the general form of equations is in agreement with the theory\nformulated by Toner and Tu.\n  Finally, we compare our analytical predictions on the stability of the\ndisordered homogeneous solution with results of individual-based simulations.\nThey show good agreement for sufficiently large densities and non-negligible\nshort-ranged repulsion. Disagreements of numerical results and the hydrodynamic\ntheory for weak short-ranged repulsion reveal the existence of a previously\nunknown phase of the model consisting of dense, nematically aligned filaments,\nwhich cannot be accounted for by the present Toner and Tu type theory of polar\nactive matter."
    },
    {
        "anchor": "Growth saturation of unstable thin films on transverse-striped\n  hydrophilic-hydrophobic micropatterns: Using three-dimensional numerical simulations, we demonstrate the growth\nsaturation of an unstable thin liquid film on micropatterned\nhydrophilic-hydrophobic substrates. We consider different transverse-striped\nmicropatterns, characterized by the total fraction of hydrophilic coverage and\nthe width of the hydrophilic stripes. We compare the growth of the film on the\nmicropatterns to the steady states observed on homogeneous substrates, which\ncorrespond to a saturated sawtooth and growing finger configurations for\nhydrophilic and hydrophobic substrates, respectively. The proposed\nmicropatterns trigger an alternating fingering-spreading dynamics of the film,\nwhich leads to a complete suppression of the contact line growth above a\ncritical fraction of hydrophilic stripes. Furthermore, we find that increasing\nthe width of the hydrophilic stripes slows down the advancing front, giving\nsmaller critical fractions the wider the hydrophilic stripes are. Using\nanalytical approximations, we quantitatively predict the growth rate of the\ncontact line as a function of the covering fraction, and predict the threshold\nfraction for saturation as a function of the stripe width.",
        "positive": "Passage Times for Polymer Translocation Pulled through a Narrow Pore: We study the passage times of a translocating polymer of length $N$ in three\ndimensions, while it is pulled through a narrow pore with a constant force $F$\napplied to one end of the polymer. At small to moderate forces, satisfying the\ncondition $FN^{\\nu}/k_BT\\lesssim1$, where $\\nu\\approx0.588$ is the Flory\nexponent for the polymer, we find that $\\tau_N$, the mean time the polymer\ntakes to leave the pore, scales as $N^{2+\\nu}$ independent of $F$, in agreement\nwith our earlier result for F=0. At strong forces, i.e., for\n$FN^{\\nu}/k_BT\\gg1$, the behaviour of the passage time crosses over to\n$\\tau_N\\sim N^2/F$. We show here that these behaviours stem from the polymer\ndynamics at the immediate vicinity of the pore -- in particular, the memory\neffects in the polymer chain tension imbalance across the pore."
    },
    {
        "anchor": "Avalanche Interpretation of the Power-Law Energy Spectrum in\n  Three-Dimensional Dense Granular Flow: Turbulence is ubiquitous in nonequilibrium systems, and it has been noted\nthat even dense granular flows exhibit characteristics that are typical of\nturbulent flow, such as the power-law energy spectrum. However, studies on the\nturbulent-like behavior of granular flows are limited to two-dimensional (2D)\nflow. We demonstrate that the statistics in three-dimensional (3D) flow are\nqualitatively different from those in 2D flow. We also elucidate that avalanche\ndynamics can explain this dimensionality dependence. Moreover, we define\nclusters of collectively moving particles that are equivalent to vortex\nfilaments. The clusters unveil complicated structures in 3D flows that are\nabsent in 2D flows.",
        "positive": "Rheology of dense granular suspensions under extensional flow: We study granular suspensions under a variety of extensional deformations and\nsimple shear using numerical simulations. The viscosity and Trouton's ratio\n(the ratio of extensional to shear viscosity) are computed as functions of\nsolids volume fraction $\\phi$ close to the limit of zero inertia. Suspensions\nof frictionless particles follow a Newtonian Trouton's ratio for $\\phi$ all the\nway up to $\\phi_0$, a universal jamming point that is independent of\ndeformation type. In contrast, frictional particles lead to a\ndeformation-type-dependent jamming fraction $\\phi_m$, which is largest for\nshear flows. Trouton's ratio consequently starts off Newtonian but diverges as\n$\\phi\\to\\phi_m$. We explain this discrepancy in suspensions of frictional\nparticles by considering the particle arrangements at jamming. While\nfrictionless particle suspensions have a nearly isotropic microstructure at\njamming, friction permits more anisotropic contact chains that allow jamming at\nlower $\\phi$ but introduce protocol dependence. Finally, we provide evidence\nthat viscous number rheology can be extended from shear to extensional\ndeformations, with a particularly successful collapse for frictionless\nparticles. Extensional deformations are an important class of rheometric flow\nin suspensions, relevant to paste processing, granulation and high performance\nmaterials."
    },
    {
        "anchor": "Symmetries and alignment of biaxial nematic liquid crystals: The possible symmetries of the biaxial nematic phase are examined against the\nimplications of the presently available experimental results. Contrary to the\nwidespread notion that biaxial nematics have orthorhombic symmetry, our study\nshows that a monoclinic ($C_{2h}$) symmetry is more likely to be the case for\nthe recently observed phase biaxiality in thermotropic bent-core and calamitc\ntetrapode nematic systems. The methodology for differentiating between the\npossible symmetries of the biaxial nematic phase by NMR and by IR spectroscopy\nmeasurements is presented in detail. The manifestations of the different\nsymmetries on the alignment of the biaxial phase are identified and their\nimplications on the measurement and quantification of biaxiality as well as on\nthe potential use of biaxial nematic liquid crystals in electro-optic\napplications are discussed.",
        "positive": "Surface Roughness and Effective Stick-Slip Motion: The effect of random surface roughness on hydrodynamics of viscous\nincompressible liquid is discussed. Roughness-driven contributions to\nhydrodynamic flows, energy dissipation, and friction force are calculated in a\nwide range of parameters. When the hydrodynamic decay length (the viscous wave\npenetration depth) is larger than the size of random surface inhomogeneities,\nit is possible to replace a random rough surface by effective stick-slip\nboundary conditions on a flat surface with two constants: the stick-slip length\nand the renormalization of viscosity near the boundary. The stick-slip length\nand the renormalization coefficient are expressed explicitly via the\ncorrelation function of random surface inhomogeneities. The effective\nstick-slip length is always negative signifying the effective slow-down of the\nhydrodynamic flows by the rough surface (stick rather than slip motion). A\nsimple hydrodynamic model is presented as an illustration of these general\nhydrodynamic results. The effective boundary parameters are analyzed\nnumerically for Gaussian, power-law and exponentially decaying correlators with\nvarious indices. The maximum on the frequency dependence of the dissipation\nallows one to extract the correlation radius (characteristic size) of the\nsurface inhomogeneities directly from, for example, experiments with torsional\nquartz oscillators."
    },
    {
        "anchor": "Mixing by Unstirring: Hyperuniform Dispersion of Interacting Particles\n  upon Chaotic Advection: We show how to achieve both fast and hyperuniform dispersions of particles in\nviscous fluids. To do so, we first extend the concept of critical random\norganization to chaotic drives. We show how palindromic sequences of chaotic\nadvection cause microscopic particles to effectively interact at long range\nthereby inhibiting critical self-organization. Based on this understanding we\ngo around this limitation and design sequences of stirring and unstirring which\nsimultaneously optimize the speed of particle spreading and the homogeneity of\nthe resulting dispersions.",
        "positive": "Topology of three-dimensional active nematic turbulence confined to\n  droplets: Active nematics contain topological defects which under sufficient activity\nmove, create and annihilate in a chaotic quasi-steady state, called active\nturbulence. However, understanding active defects under confinement is an open\nchallenge, especially in three-dimensions. Here, we demonstrate the topology of\nthree-dimensional active nematic turbulence under the spherical confinement,\nusing numerical modelling. In such spherical droplets, we show the\nthree-dimensional structure of the topological defects, which due to closed\nconfinement emerge in the form of closed loops or surface-to-surface spanning\nline segments. In the turbulent regime, the defects are shown to be strongly\nspatially and time varying, with ongoing transformations between positive\nwinding, negative winding and twisted profiles, and with defect loops of zero\nand non-zero topological charge. The timeline of the active turbulence is\ncharacterised by four types of bulk topology-linked events --- breakup,\nannihilation, coalescence and cross-over of the defects --- which we discuss\ncould be used for the analysis of the active turbulence in different\nthree-dimensional geometries. The turbulent regime is separated by a first\norder structural transition from a low activity regime of a steady-state vortex\nstructure and an offset single point defect. We also demonstrate coupling of\nsurface and bulk topological defect dynamics by changing from strong\nperpendicular to inplane surface alignment. More generally, this work is aimed\nto provide insight into three-dimensional active turbulence, distinctly from\nthe perspective of the topology of the emergent three-dimensional topological\ndefects."
    },
    {
        "anchor": "Shear response of a smectic film stabilized by an external field: The response of a field-stabilized two-dimensional smectic to shear stress is\ndiscussed. Below a critical temperature the smectic film exhibits elastic\nresponse to an infinitesimal shear stress normal to the layering. At finite\nstresses free dislocations nucleate and relax the applied stress. The coupling\nof the dislocation current to the stress results in non-newtonian viscous flow.\nThe flow profile in a channel geometry is shown to change qualitatively from a\npower-law dependence to a Poiseuille-like profile opon increasing the pressure\nhead.",
        "positive": "Relevance of the speed and direction of pulling in simple modular\n  proteins: A theoretical analysis of the unfolding pathway of simple modular proteins in\nlength- controlled pulling experiments is put forward. Within this framework,\nwe predict the first module to unfold in a chain of identical units,\nemphasizing the ranges of pulling speeds in which we expect our theory to hold.\nThese theoretical predictions are checked by means of steered molecular\ndynamics of a simple construct, specifically a chain composed of two\ncoiled-coils motives, where anisotropic features are revealed. These\nsimulations also allow us to give an estimate for the range of pulling\nvelocities in which our theoretical approach is valid."
    },
    {
        "anchor": "Dielectric and conductivity relaxation in mixtures of glycerol with LiCl: We report a thorough dielectric characterization of the alpha relaxation of\nglass forming glycerol with varying additions of LiCl. Nine salt concentrations\nfrom 0.1 - 20 mol% are investigated in a frequency range of 20 Hz - 3 GHz and\nanalyzed in the dielectric loss and modulus representation. Information on the\ndc conductivity, the dielectric relaxation time (from the loss) and the\nconductivity relaxation time (from the modulus) is provided. Overall, with\nincreasing ion concentration, a transition from reorientationally to\ntranslationally dominated behavior is observed and the translational ion\ndynamics and the dipolar reorientational dynamics become successively coupled.\nThis gives rise to the prospect that by adding ions to dipolar glass formers,\ndielectric spectroscopy may directly couple to the translational degrees of\nfreedom determining the glass transition, even in frequency regimes where\nusually strong decoupling is observed.",
        "positive": "Localization of a random heteropolymer onto a surface: We study the localization of a random heteropolymer onto an homogeneous\nsurface, the problem which is equivalent to the wetting of an interface at\ndisordered substrate in two dimensions, via replica trick by using the Green's\nfunction technique. The exact treatment of one- and two-replica binding states\nis used to compute the free energy of the random heteropolymer. We present\nanalytical results for two particular cases: {\\it (i)} nearly statistically\nsymmetric copolymer in the vicinity of the threshold of the annealed problem,\nand {\\it (ii)} the asymmetric polymer with the interaction part of the annealed\nHamiltonian being nearly zero. In both cases the localization is due to\ntwo-replica binding states. In the case {\\it (i)} the two-replica binding state\nexists both above and below of the one-replica binding state. In the case {\\it\n(ii)} the energy of the two-replica binding state at the transition is finite.\nA schematic phase diagram of the localization-delocalization transition of the\nrandom heteropolymer is suggested."
    },
    {
        "anchor": "Nonlinear molecular deformations give rise to stress stiffening,\n  yielding and non-uniform stress propagation in actin networks: We use optical tweezers microrheology and fluorescence microscopy to apply\nnonlinear microscale strains to entangled and crosslinked actin networks, and\nmeasure the resulting stress and actin filament deformations. We couple\nnonlinear stress response and subsequent relaxation to the velocity profiles of\nindividual fluorescent-labeled actin segments at varying times throughout the\nstrain and varying distances from the strain path to determine the underlying\nmolecular dynamics that give rise to the debated nonlinear response and stress\npropagation of crosslinked and entangled actin networks at the microscale. We\nshow that initial stress stiffening arises from acceleration of strained\nfilaments due to molecular extension along the strain, while softening and\nyielding is coupled to filament deceleration, halting and recoil. We\ndemonstrate a surprising non-monotonic dependence of velocity profiles on\ncrosslinker concentration. Namely, networks with no crosslinks or substantial\ncrosslinks both exhibit fast initial filament velocities and reduced molecular\nrecoil while intermediate crosslinker concentrations display reduced velocities\nand increased recoil. We show that these collective results are due to a\nbalance of network elasticity and transient crosslinker unbinding and\nrebinding. We further show that elasticity and relaxation timescales display an\nexponential dependence on crosslinker concentration that reveal that crosslinks\ndominate entanglement dynamics when the length between crosslinkers becomes\nsmaller than the length between entanglements. In accord with recent\nsimulations, our relaxation dynamics demonstrate that post-strain stress can be\nlong-lived in crosslinked networks by distributing stress to a small fraction\nof highly-strained connected filaments that span the network and sustain the\nload, thereby allowing the rest of the network to recoil and relax.",
        "positive": "Liquid-liquid interfacial tension of electrolyte solutions: It is theoretically shown that the excess liquid-liquid interfacial tension\nbetween two electrolyte solutions as a function of the ionic strength I behaves\nasymptotically as O(- I^0.5) for small I and as O(+- I) for large I. The former\nregime is dominated by the electrostatic potential due to an unequal\npartitioning of ions between the two liquids whereas the latter regime is\nrelated to a finite interfacial thickness. The crossover between the two\nasymptotic regimes depends sensitively on material parameters suggesting that,\ndepending on the actual system under investigation, the experimentally\naccessible range of ionic strengths can correspond to either the small or the\nlarge ionic strength regime. In the limiting case of a liquid-gas surface where\nion partitioning is absent, the image chage interaction can dominate the\nsurface tension for small ionic strength I such that an Onsager-Samaras\nlimiting law O(- I ln(I)) is expected. The proposed picture is consistent with\nmore elaborate models and published measurements."
    },
    {
        "anchor": "Micellisation vs aggregation in dilute solutions of amphiphilic\n  heteropolymers: In recent experiments involving PNIPAM copolymers it has been observed that\nstable spherical nanoparticles are being formed by association of several\nchains in poor aqueous solution instead of aggregation. This type of mesoscopic\nstructures called mesoglobules has an extremely monodispersed size\ndistribution. Previously we have studied theoretically formation of clusters\nconsisting of several chains in dilute solutions of amphiphilic heteropolymers.\nWe have seen that the mesoglobules often possess an essentially micellar\nstructure. In the current work we argue that formation of mesoglobules is\nstrongly sequence and concentration dependent. In particular, by means of\nlattice Monte Carlo simulation we consider structures formed by a number of\ntri-block sequences and their certain mutations. For sequences consisting of\ntwo hydrophilic ends with a hydrophobic middle the size distribution of the\nresulting particles is rather narrow, i.e. mesoglobules are being formed.\nHowever, in the case of sequences with two hydrophobic ends and a hydrophilic\nmiddle a new type of structures seems to be prevalent. These consist of small\nmesoglobules interconnected by hydrophilic bridges. Clearly, on increasing the\nconcentration these networked structures would play an important role resulting\nin a rapid onset of a gel-like behaviour.",
        "positive": "Acid-induced gelation of carboxymethylcellulose solutions: The present work offers a comprehensive description of the acid-induced\ngelation of carboxymethylcellulose (CMC), a water-soluble derivative of\ncellulose broadly used in numerous applications ranging from food packaging to\nbiomedical engineering. Linear viscoelastic properties measured at various pH\nand CMC contents allow us to build a sol-gel phase diagram, and show that CMC\ngels exhibit broad power-law viscoelastic spectra that can be rescaled onto a\nmaster curve following a time-composition superposition principle. These\nresults demonstrate the microstructural self-similarity of CMC gels, and\ninspire a mean-field model based on hydrophobic inter-chain association that\naccounts for the sol-gel boundary over the entire range of CMC content under\nstudy. Neutron scattering experiments further confirm this picture and suggest\nthat CMC gels comprise a fibrous network crosslinked by aggregates. Finally,\nlow-field NMR measurements offer an original signature of acid-induced gelation\nfrom the solvent perspective. Altogether, these results open avenues for\nprecise manipulation and control of CMC-based hydrogels."
    },
    {
        "anchor": "Static and dynamical properties of a hard-disk fluid confined to a\n  narrow channel: The thermodynamic properties of disks moving in a channel sufficiently narrow\nthat they can collide only with their nearest neighbors can be solved exactly\nby determining the eigenvalues and eigenfunctions of an integral equation.\nUsing it we have determined the correlation length $\\xi$ of this system. We\nhave developed an approximate solution which becomes exact in the high density\nlimit. It describes the system in terms of defects in the regular zigzag\narrangement of disks found in the high-density limit. The correlation length is\nthen effectively the spacing between the defects. The time scales for defect\ncreation and annihilation are determined with the help of transition-state\ntheory, as is the diffusion coefficient of the defects, and these results are\nfound to be in good agreement with molecular dynamics simulations. On\ncompressing the system with the Lubachevsky--Stillinger procedure, jammed\nstates are obtained whose packing fractions $\\phi_J$ are a function of the\ncompression rate $\\gamma$. We find a quantitative explanation of this\ndependence by making use of the Kibble--Zurek hypothesis. We have also\ndetermined the point-to-set length scale $\\xi_{PS}$ for this system. At a\npacking fraction $\\phi$ close to its largest value $\\phi_{\\text{max}}$,\n$\\xi_{PS}$ has a simple power law divergence, $\\xi_{PS} \\sim\n1/(1-\\phi/\\phi_{\\text{max}})$, while $\\xi$ diverges much faster, $\\ln(\\xi) \\sim\n1/(1-\\phi/\\phi_{\\text{max}})$.",
        "positive": "Generalizing the Debye-Huckel equation in terms of density functional\n  integral: We discuss the validity of generalized Debye-H\\\"uckel (GDH) equation proposed\nby Fisher {\\itshape et al.} from the functional integral point of view. The GDH\ntheory considers fluctuations around prescribed densities of positive and\nnegative charges. Hence we first formulate a density functional integral\nexpression for the canonical system of Coulomb gas, and also demonstrate that\nthis is a dual form to the Sine-Gordon theory. Our formalism reveals the\nfollowing: (i) The induced charge distribution around supposed density favors\nnot only the cancellation of additional electrostatic potential like the\noriginal DH theory, but also the countervailing of chemical potential\ndifference between imposed and equilibrium value. (ii) As a consequence\napparent charge, absent in the GDH equation, comes out in our generalized\nequation. (iii) That is, the GDH equation holds only in special cases."
    },
    {
        "anchor": "The Functional Form of Angular Forces around Transition Metal Ions in\n  Biomolecules: A method for generating angular forces around $\\sigma$-bonded transition\nmetal ions is generalized to treat $\\pi$-bonded configurations. The theoretical\napproach is based on an analysis of a ligand-field Hamiltonian based on the\nmoments of the electron state distribution. The functional forms that are\nobtained involve a modification of the usual expression of the binding energy\nas a sum of ligand-ligand interactions, which however requires very little\nincreased in CPU time. The angular interactions have simple forms involving sin\nand cos functions, whose relative weights depend on whether the ligands are\n$\\sigma$- or $\\pi$-bonded. They describe the ligand-field stabilization energy\nto an accuracy of about 10%. The resulting force field is used to model the\nstructure of small clusters, including fragments of the copper blue protein\nstructure. Large deviations from the typical square copper coordination are\nfound when $\\pi$-bonded ligands are present.",
        "positive": "Pattern formation and the mechanics of a motor-driven filamentous system\n  confined by rigid membranes: Pattern formation and the mechanics of a mixture of actin filaments and\nmyosin motors that is confined by a rigid membrane is investigated. By using a\ncoarse-grained molecular dynamics model, we demonstrate that the competition\nbetween the depletion force and the active force of the motors gives rise to\nactin accumulation in the membrane vicinity. The resulting actomyosin structure\nexerts pressure on the membrane, that, due to nematic alignment of the\nfilaments, converges to a constant for large motor active force. The results\nare independent of filament length and membrane curvature, indicating the\nuniversality of this phenomenon. Thus, this study proposes a novel mechanism by\nwhich the compounds of the cytoskeleton can self-organize into a higher-order\nstructure."
    },
    {
        "anchor": "Boundary-roughness effects in nematic liquid crystals: We study the equilibrium configuration of a nematic liquid crystal bounded by\na rough surface. The wrinkling of the surface induces a partial melting in the\ndegree of orientation. This softened region penetrates the bulk up to a length\nscale which turns out to coincide with the characteristic wave length of the\ncorrugation. Within the boundary layer where the nematic degree of orientation\ndecreases, the tilt angle steepens and gives rise to a nontrivial structure,\nthat may be interpreted in terms of an effective weak anchoring potential. We\ndetermine how the effective surface extrapolation length is related to the\nmicroscopic anchoring parameters. We also analyze the crucial role played by\nthe boundary conditions assumed on the degree of orientation. Quite different\nfeatures emerge depending on whether they are Neumann- or Dirichlet-like. These\nfeatures may be useful to ascertain experimentally how the degree of\norientation interacts with an external boundary.",
        "positive": "Design principles and optimal performance for molecular motors under\n  realistic constraints: The performance of a molecular motor, characterized by its power output and\nenergy efficiency, is investigated in the motor design space spanned by the\nstepping rate function and the motor-track interaction potential. Analytic\nresults and simulations show that a gating mechanism that restricts forward\nstepping in a narrow window in configuration space is needed for generating\nhigh power at physiologically relevant loads. By deriving general\nthermodynamics laws for nonequilibrium motors, we find that the maximum torque\n(force) at stall is less than its theoretical limit for any realistic\nmotor-track interactions due to speed fluctuations. Our study reveals a\ntradeoff for the motor- track interaction: while a strong interaction generates\na high power output for forward steps, it also leads to a higher probability of\nwasteful spontaneous back steps. Our analysis and simulations show that this\ntradeoff sets a fundamental limit to the maximum motor efficiency in the\npresence of spontaneous back steps, i.e., loose-coupling. Balancing this\ntradeoff leads to an optimal design of the motor-track interaction for\nachieving a maximum efficiency close to 1 for realistic motors that are not\nperfectly coupled with the energy source.Comparison with existing data and\nsuggestions for future experiments are discussed."
    },
    {
        "anchor": "Collective dynamics in phospholipid bilayers investigated by inelastic\n  neutron scattering: Exploring the dynamics of biological membranes with\n  neutrons: We present the first inelastic neutron scattering study of the short\nwavelength dynamics in a phospholipid bilayer. We show that inelastic neutron\nscattering using a triple-axis spectrometer at the high flux reactor of the ILL\nyields the necessary resolution and signal to determine the dynamics of model\nmembranes. The results can quantitatively be compared to recent Molecular\nDynamics simulations. Reflectivity, in-plane correlations and the corresponding\ndynamics can be measured simultaneously to gain a maximum amount of\ninformation. With this method, dispersion relations can be measured with a high\nenergy resolution. Structure and dynamics in phospholipid bilayers, and the\nrelation between them, can be studied on a molecular length scale.",
        "positive": "Kinetics of non-ionic surfactant adsorption at a fluid-fluid interface\n  from a micellar solution: The kinetics of non-ionic surfactant adsorption at a fluid-fluid interface\nfrom a micellar solution is considered theoretically. Our model takes into\naccount the effect of micelle relaxation on the diffusion of the free\nsurfactant molecules. It is shown that non-ionic surfactants undergo either a\ndiffusion or a kinetically limited adsorption according to the characteristic\nrelaxation time of the micelles. This gives a new interpretation for the\nobserved dynamical surface tension of micellar solutions."
    },
    {
        "anchor": "Tracking Rotational Diffusion of Colloidal Clusters: We describe a novel method of tracking the rotational motion of clusters of\ncolloidal particles. Our method utilizes rigid body transfor- mations to\ndetermine the rotations of a cluster and extends conventional proven particle\ntracking techniques in a simple way, thus facilitating the study of rotational\ndynamics in systems containing or composed of colloidal clusters. We test our\nmethod by measuring dynamical properties of simulated Brownian clusters under\nconditions relevant to microscopy experiments. We then use the technique to\ntrack and describe the motions of a real colloidal cluster imaged with confocal\nmicroscopy.",
        "positive": "Phase diffusion of Bose-Einstein Condensation close to zero temperature: The correlation function of the quantum fluctuations due to collective\nexcitations is calculated and used to investigate the phase diffusion of a\nBose-Einstein condensate close to zero temperature. It is shown that the phase\ndiffusion time of the condensate is much longer than the result obtained by\nassuming that the correlation time of the quantum fluctuations is infinity."
    },
    {
        "anchor": "Fundamental-measure density functional for the fluid of aligned hard\n  hexagons: New insights in fundamental measure theory: In this article we obtain a fundamental measure functional for the model of\naligned hard hexagons in the plane. Our aim is not just to provide a functional\nfor a new, admittedly academic, model, but to investigate the structure of\nfundamental measure theory. A model of aligned hard hexagons has similarities\nwith the hard disk model. Both share \"lost cases\", i.e. admit configurations of\nthree particles in which there is pairwise overlap but not triple overlap.\nThese configurations are known to be problematic for fundamental measure\nfunctionals, which are not able to capture their contribution correctly. This\nfailure lies in the inability of these functionals to yield a correct low\ndensity limit of the third order direct correlation function. Here we derive\nthe functional by projecting aligned hard cubes on the plane x+y+z=0. The\ncorrect dimensional crossover behavior of these functionals permits us to\nfollow this strategy. The functional of aligned hard cubes, however, does not\nhave lost cases, so neither had the resulting functional for aligned hard\nhexagons. The latter exhibits, in fact, a peculiar structure as compared to the\none for hard disks. It depends on a uniparametric family of weighted densities\nthrough a new term not appearing in the functional for hard disks. Apart from\nstudying the freezing of this system, we discuss the implications of the\nfunctional structure for new developments of fundamental measure theory.",
        "positive": "Motility and Phototaxis of $Gonium$, the Simplest Differentiated\n  Colonial Alga: Green algae of the $Volvocine$ lineage, spanning from unicellular\n$Chlamydomonas$ to vastly larger $Volvox$, are models for the study of the\nevolution of multicellularity, flagellar dynamics, and developmental processes.\nPhototactic steering in these organisms occurs without a central nervous\nsystem, driven solely by the response of individual cells. All such algae spin\nabout a body-fixed axis as they swim; directional photosensors on each cell\nthus receive periodic signals when that axis is not aligned with the light. The\nflagella of $Chlamydomonas$ and $Volvox$ both exhibit an adaptive response to\nsuch signals in a manner that allows for accurate phototaxis, but in the former\nthe two flagella have distinct responses, while the thousands of flagella on\nthe surface of spherical $Volvox$ colonies have essentially identical\nbehaviour. The planar 16-cell species $Gonium~pectorale$ thus presents a\nconundrum, for its central 4 cells have a $Chlamydomonas$-like beat that\nprovide propulsion normal to the plane, while its 12 peripheral cells generate\nrotation around the normal through a $Volvox$-like beat. Here, we combine\nexperiment, theory, and computations to reveal how $Gonium$, perhaps the\nsimplest differentiated colonial organism, achieves phototaxis. High-resolution\ncell tracking, particle image velocimetry of flagellar driven flows, and\nhigh-speed imaging of flagella on micropipette-held colonies show how, in the\ncontext of a recently introduced model for $Chlamydomonas$ phototaxis, an\nadaptive response of the peripheral cells alone leads to photo-reorientation of\nthe entire colony. The analysis also highlights the importance of local\nvariations in flagellar beat dynamics within a given colony, which can lead to\nenhanced reorientation dynamics."
    },
    {
        "anchor": "Assembly and Phase Transitions within Colloidal Crystals: Micrometre sized colloidal particles can be viewed as large atoms with\ntailorable size, shape and interactions. These building blocks can assemble\ninto extremely rich structures and phases, in which the thermal motions of\nparticles can be directly imaged and tracked using optical microscopy. Hence,\ncolloidal particles are excellent model systems for studying phase transitions,\nespecially for poorly understood kinetic and nonequilibrium microscale\nprocesses. Advances in colloid fabrication, assembly and computer simulations\nhave opened up numerous possibilities for such research. In this Review, we\ndescribe recent progress in the study of colloidal crystals composed of tunable\nisotropic spheres, anisotropic particles and active particles. We focus on\nadvances in crystallization, melting and solid solid transitions, and highlight\nchallenges and future perspectives in phase transition studies within colloidal\ncrystals.",
        "positive": "Swimmer-tracer scattering at low Reynolds number: Understanding the stochastic dynamics of tracer particles in active fluids is\nimportant for identifying the physical properties of flow generating objects\nsuch as colloids, bacteria or algae. Here, we study both analytically and\nnumerically the scattering of a tracer particle in different types of\ntime-dependent, hydrodynamic flow fields. Specifically, we compare the tracer\nmotion induced by an externally driven colloid with the one generated by\nvarious self-motile, multi-sphere swimmers. Our results suggest that force-free\nswimmers generically induce loop-shaped tracer trajectories. The specific\ntopological structure of these loops is determined by the hydrodynamic\nproperties of the microswimmer. Quantitative estimates for typical experimental\nconditions imply that the loops survive on average even if Brownian motion\neffects are taken into account."
    },
    {
        "anchor": "Implementation of the control and data acquisition system for a small\n  angle neutron scattering spectrometer according to the \"Juelich-Munich\n  standard\": In Forschungszentrum Juelich the control and data acquisition systems for\nseveral neutron spectrometers are being built. Because some of these\nspectrometers will be commissioned to the new research reactor FRM-II at the\ntechnical university of Munich, there was a joint effort with the\ninstrumentation group of the FRM-II to establish the \"Juelich-Munich standard\",\nwhich is basically a collection of tools and devices which are used for the\nimplementation of the spectrometers. This includes: Siemens S7 PLCs for all\naxis movement issues, PROFIBUS DP for the connection of slow control equipment\nin the front end, TACO Middleware running on PC-Systems with Linux, python for\nscripting and Qt for the implementation of GUIs. The paper describes the\nimplementation the control and data acquisition system of the KWS-1, the first\nexperiment built according to the above standard",
        "positive": "Ferroelectric domain formation in discotic liquid crystals : Monte Carlo\n  study on the influence of boundary conditions: The realization of a spontaneous macroscopic ferroelectric order in fluids of\nanisotropic mesogens is a topic of both fundamental and technological interest.\nRecently, we demonstrated that a system of dipolar achiral disklike ellipsoids\ncan exhibit long-searched ferroelectric liquid crystalline phases of dipolar\norigin. In the present work, extensive off-lattice Monte Carlo simulations are\nused to investigate the phase behavior of the system under the influences of\nthe electrostatic boundary conditions that restrict any global polarization. We\nfind that the system develops strongly ferroelectric slablike domains\nperiodically arranged in an antiferroelectric fashion. Exploring the phase\nbehavior at different dipole strengths, we find existence of the ferroelectric\nnematic and ferroelectric columnar order inside the domains. For higher dipole\nstrengths, a biaxial phase is also obtained with a similar periodic array of\nferroelectric slabs of antiparallel polarizations. We have studied the\ndepolarizing effects by using both the Ewald summation and the spherical\ncut-off techniques. We present and compare the results of the two different\napproaches of considering the depolarizing effects in this anisotropic system.\nIt is explicitly shown that the domain size increases with the system size as a\nresult of considering longer range of dipolar interactions. The system exhibits\npronounced system size effects for stronger dipolar interactions. The results\nprovide strong evidence to the novel understanding that the dipolar\ninteractions are indeed sufficient to produce long range ferroelectric order in\nanisotropic fluids."
    },
    {
        "anchor": "Field theory for mechanical criticality in disordered fiber networks: Strain-controlled criticality governs the elasticity of jamming and fiber\nnetworks. While the upper critical dimension of jamming is believed to be\n$d_u$=2, non mean-field exponents are observed in numerical studies of 2D and\n3D fiber networks. The origins of this remains unclear. In this study we\npropose a minimal mean-field model for strain-controlled criticality of fiber\nnetworks. We then extend this to a phenomenological field theory, in which non\nmean-field behavior emerges as a result of the disorder in the network\nstructure. We predict that the upper critical dimension for such systems is\n$d_u$=4 using a Gaussian approximation. Moreover, we identify an order\nparameter for the phase transition, which has been lacking for fiber networks\nto date.",
        "positive": "Probing water structures in nanopores using tunneling currents: We study the effect of volumetric constraints on the structure and electronic\ntransport properties of distilled water in a nanopore with embedded electrodes.\nCombining classical molecular dynamics simulations with quantum scattering\ntheory, we show that the structural motifs water assumes inside the pore can be\nprobed directly by tunneling. In particular, we show that the current does not\nfollow a simple exponential curve at a critical pore diameter of about 8 {\\AA},\nrather it is larger than the one expected from simple tunneling through a\nbarrier. This is due to a structural transition from bulk-like to \"nanodroplet\"\nwater domains. Our results can be tested with present experimental capabilities\nto develop our understanding of water as a complex medium at nanometer length\nscales."
    },
    {
        "anchor": "Rubber friction and tire dynamics: We propose a simple rubber friction law, which can be used, e.g., in models\nof tire (and vehicle) dynamics. The friction law is tested by comparing\nnumerical results to the full rubber friction theory (B.N.J. Persson, J. Phys.:\nCondensed Matter 18, 7789 (2006)). Good agreement is found between the two\ntheories. We describe a two-dimensional (2D) tire model which combines the\nrubber friction model with a simple mass-spring description of the tire body.\nThe tire model is very flexible and can be used to calculate accurate mu-slip\n(and the self-aligning torque) curves for braking and cornering or combined\nmotion (e.g., braking during cornering). We present numerical results which\nillustrate the theory. Simulations of Anti-Blocking System (ABS) braking are\nperformed using two simple control algorithms.",
        "positive": "Protein solutions close to liquid-liquid phase separation exhibit a\n  universal osmotic equation of state and dynamical behavior: Liquid-liquid phase separation (LLPS) of protein solutions is governed by\nhighly complex protein-protein interactions. Nevertheless, it has been\nsuggested that based on the extended law of corresponding states (ELCS), as\nproposed for colloids with short-range attractions, one can rationalize not\nonly the thermodynamics, but also the structure and dynamics of such systems.\nThis claim is systematically and comprehensively tested here by static and\ndynamic light scattering experiments. Spinodal lines, the isothermal osmotic\ncompressibility $\\kappa_\\text{T}$ and the relaxation rate of concentration\nfluctuations $\\Gamma$ are determined for protein solutions in the vicinity of\nLLPS. All these quantities are found to exhibit a corresponding-states\nbehavior. This means that, for different solution conditions, these quantities\nare essentially the same if considered at similar reduced temperature or second\nvirial coefficient. For moderately concentrated solutions, the volume fraction\n$\\phi$ dependence of $\\kappa_\\text{T}$ and $\\Gamma$ can be consistently\ndescribed by Baxter's model of adhesive hard spheres. The off-critical,\nasymptotic $T$ behavior of $\\kappa_\\text{T}$ and $\\Gamma$ close to LLPS is\nconsistent with the scaling laws predicted by mean-field theory. Thus, the\npresent work aims at a comprehensive experimental test of the applicability of\nthe ELCS to structural and dynamical properties of concentrated protein\nsolutions."
    },
    {
        "anchor": "From Disks to Channels: Dynamics of Active Nematics Confined to an\n  Annulus: Confinement can be used to systematically tame turbulent dynamics occurring\nin active fluids. Although periodic channels are the simplest geometries to\nstudy confinement numerically, the corresponding experimental realizations\nrequire closed racetracks. Here, we computationally study 2D active nematics\nconfined to such a geometry -- an annulus. By systematically varying the\nannulus inner radius and channel width, we bridge the behaviors observed in the\npreviously studied asymptotic limits of the annulus geometry: a disk and an\ninfinite channel. We identify new steady-state behaviors, which reveal the\ninfluence of boundary curvature and its interplay with confinement. We also\nshow that, below a threshold inner radius, the dynamics are insensitive to\ntopological constraints imposed by boundary conditions. We explain this\ninsensitivity through a simple scaling analysis. Our work sheds further light\non design principles for using confinement to control the dynamics of active\nnematics.",
        "positive": "Slope of Dry Granular Materials Surface is Generally Curved: As if it has become a consensus that the slope of the granular heap is\nstraight, and from that, an angle of repose is defined. However, closer\ninspection shows that the slopes are not truly straight, instead, more often\nthey have convex shapes, although with small convexity. Similar curvature is\nobserved on the sand dunes' surfaces. We derive equations together with\nexperiments on 10 types of granular materials to show that, in general, the\nslope of the granular heap is convex while the straight slope is a critical\nstate that rarely occurs. The angle of repose is allowed to vary within a\nnarrow range around a critical value. If the angle of repose is slightly\ngreater (smaller) than the critical value, the slope is convex (concave). The\nmodel also answers why the surfaces of granular heaps, including sand dunes,\nare more often convex rather than concave or straight, and advocate the\nsimultaneous estimation of the coefficient of friction on the grain and the\ntype of packing in the heap. The results might open new understandings related\nto granular material properties as well as sand transport and geological\nrecords in several deserts."
    },
    {
        "anchor": "Comment on: \"The Frenkel Line: a direct experimental evidence for the\n  new thermodynamic boundary\": In a recent publication (D. Bolmatov et al. Sci.Rep. 5, 15850 (2015)) the\nexperimental observation of structural transformations on crossing the Frenkel\nline in supercritical argon is claimed. Here we show that no experimental\nevidence of the structural transformation was presented. The reported\nexperimental observations which Bolmatov et al. claim as evidence of a\ntransition across the Frenkel line are instead due to the irregularity of the\nexperimental (P,T) path in their work.",
        "positive": "Global Memory from Local Hysteresis in an Amorphous Solid: A disordered material that cannot relax to equilibrium, such as an amorphous\nor glassy solid, responds to deformation in a way that depends on its past. In\nexperiments we train a 2D athermal amorphous solid with oscillatory shear, and\nshow that a suitable readout protocol reveals the shearing amplitude. When\nshearing alternates between two amplitudes, signatures of both values are\nretained only if the smaller one is applied last. We show that these behaviors\narise because individual clusters of rearrangements are hysteretic and\ndissipative, and because different clusters respond differently to shear. These\nroles for hysteresis and disorder are reminiscent of the return-point memory\nseen in ferromagnets and many other systems. Accordingly, we show how a simple\nmodel of a ferromagnet can reproduce key results of our experiments and of\nprevious simulations. Unlike ferromagnets, amorphous solids' disorder is\nunquenched; they require \"training\" to develop this behavior."
    },
    {
        "anchor": "Flocking in Binary Mixtures of Anti-aligning Self-propelled Particles: We consider two species of self-propelled point particles: A-particles and\nB-particles. The orientations between nearby particles are subject to pair\ninteractions of different strength for A-A-, A-B-(=B-A-) and B-B-interactions,\nrespectively. Even if all interactions involved are repelling, that is, if they\nlocally favor anti-alignment between each pair of particles, we find global\npolar order of both A-particles and B-particles We find qualitative agreement\nbetween agent-based simulations and mean field theory. Beyond mean field, we\ndevelop a Boltzmann-scattering theory based on one-sided molecular chaos that\nyields excellent quantitative agreement with simulations for dilute systems.\nFor large systems, we find, depending on parameters, either\nmicro-phase-separation or static patterns with either patches or stripes that\ncarry different polarization orientations.",
        "positive": "Quantum turbulence in condensate collisions: an application of the\n  classical field method: We apply the classical field method to simulate the production of correlated\natoms during the collision of two Bose-Einstein condensates. Our\nnon-perturbative method includes the effect of quantum noise, and provides for\nthe first time a theoretical description of collisions of high density\ncondensates with very large out-scattered fractions. Quantum correlation\nfunctions for the scattered atoms are calculated from a single simulation, and\nshow that the correlation between pairs of atoms of opposite momentum is rather\nsmall. We also predict the existence of quantum turbulence in the field of the\nscattered atoms--a property which should be straightforwardly measurable."
    },
    {
        "anchor": "Mean joint residence time of two Brownian particles in a sphere: We calculate the mean joint residence time of two Brownian particles in a\nsphere, for very general initial conditions. In particular, we focus on the\ndependence of this residence time as a function of the diffusion coefficients\nof the two particles. Our results can be useful for describing kinetics of\nbimolecular diffusion controlled reactions activated by catalytic sites.",
        "positive": "Exploring cogging free magnetic gears: The coupling of two rotating spherical magnets is investigated\nexperimentally, with particular emphasis on those motions where the driven\nmagnet follows the driving one with a uniform angular speed, which is a feature\nof the so called cogging free couplings. The experiment makes use of standard\nequipment and digital image processing. The theory for these couplings is based\non fundamental dipole-dipole interactions with analytically accessible\nsolutions. Technical applications of this kind of coupling are foreseeable\nparticularly for small machines, an advantage which also comes handy for\nclassroom demonstrations of this feature of the fundamental concept of\ndipole-dipole coupling."
    },
    {
        "anchor": "Theoretical rheo-physics of silk: Intermolecular associations reduce the\n  critical specific work for flow-induced crystallisation: Silk is a semi-dilute solution of randomly coiled associating polypeptide\nchains that crystallise following the stretch-induced disruption, in the strong\nextensional flow of extrusion, of the solvation\n  shell around their amino acids. We propose that natural silk spinning\nexploits both the exponentially-broad stretch-distribution generated by\nassociating polymers in extensional flow and the criterion of a critical\nconcentration of sufficiently-stretched chains to nucleate flow-induced\ncrystallisation. To investigate the specific-energy input needed to reach this\ncriterion in start-up flow, we have coupled a model for the coarse-grained\nBrownian dynamics of the chain to the stochastic, strain-dependent binding and\nunbinding of their associations. Our simulations indicate that the associations\nhamper chain alignment in the initial slow flow, but, on the other hand,\nfacilitate chain stretching at low specific work at later, high rates. We\nidentify a minimum in the critical specific work at a strain rate just above\nthe stretch transition (i.e, where the mean stretch diverges), which we explain\nin terms of analytical solutions of a two-state master equation. We further\ndiscuss how the silkworm appears to exploit the chemical tunability of the\nassociations to optimise chain alignment and stretching in different locations\nalong the spinning duct: this delicate mechanism also highlights the potential\nbiomimetic industrial benefits of chemically tunable processing of synthetic\nassociation polymers.",
        "positive": "A model of conductivity in polymer films with two conductivity states: We suppose and develop a simple quantitative model of polymer film\nconductivity. This model can be seen as a further development of the ideas of\nVlasov, Apresyan et al. The main point of the model is that conducting islands\nexist, and the charge transfer between the islands is carried out by mobile\nsegments of polymer molecules. This model quantitatively describes the presence\nof two states of conductivity, and the current stabilization phenomena, and it\npredicts the temperature dependence of conductivity, and the dependence of\nconductivity on the thickness of the polymer film. The pressure-driven\ntransition to high-conductivity is described only qualitatively in this model."
    },
    {
        "anchor": "Polymer translocation out of confined environments: We consider the dynamics of polymer translocation out of confined\nenvironments. Analytic scaling arguments lead to the prediction that the\ntranslocation time scales like $\\tau\\sim\nN^{\\beta+\\nu_{2D}}R^{1+(1-\\nu_{2D})/\\nu}$ for translocation out of a planar\nconfinement between two walls with separation $R$ into a 3D environment, and\n$\\tau \\sim N^{\\beta+1}R$ for translocation out of two strips with separation\n$R$ into a 2D environment. Here, $N$ is the chain length, $\\nu$ and $\\nu_{2D}$\nare the Flory exponents in 3D and 2D, and $\\beta$ is the scaling exponent of\ntranslocation velocity with $N$, whose value for the present choice of\nparameters is $\\beta \\approx 0.8$ based on Langevin dynamics simulations. These\nscaling exponents improve on earlier predictions.",
        "positive": "Lattice symmetries and the topological protected transport of colloidal\n  particles: The topologically protected transport of colloidal particles on top of\nmagnetic patterns of all possible single lattice constant two dimensional\nmagnetic point group symmetries is studied experimentally, theoretically, and\nwith numerical simulations. We examine the transport of colloidal particles in\nresponse to modulation loops of the external field. We classify the modulation\nloops into topologically distinct classes causing different transport. We show\nthat the lattice symmetry has a profound influence on the transport modes, the\naccessibility of transport networks, and the individual addressability of\nparamagnetic versus diamagnetic colloidal particles. We show how the transport\nof colloidal particles above a two fold symmetric stripe pattern changes from\nuniversal adiabatic transport at large elevations via a topologically protected\nratchet motion at intermediate elevations toward a non-transport regime at low\nelevations. Transport above four fold symmetric patterns is closely related to\nthe transport above two fold symmetric patterns. There exists a family of three\nfold symmetric patterns that vary as a function of the phase of the pattern. We\nshow how this family can be divided into two topologically distinct classes\nsupporting different transport modes and being protected by proper and improper\nsix fold symmetries. Both classes support individual control over the transport\nof paramagnetic and diamagnetic particles. We discuss the topological\ntransition when moving the phase from one class of pattern to the other class.\nThe similarities and the differences in the lattice symmetry protected\ntransport of classical over-damped colloidal particles versus the topologically\nprotected transport in quantum mechanical systems are emphasized"
    },
    {
        "anchor": "Resolving a controversy about adhesion in sliding contacts: An interesting recent paper by Menga, Carbone & Dini (MCD, 2018, [1]),\nsuggests that in sliding adhesive contacts, the contact area should increase\ndue to tangential shear stresses at the interface, assumed to be constant and\ncorresponding to a material constant. This is not observed in the known\nexperiments, and is in sharp contrast with all the classical theories about the\ntransition from stick to sliding, both in the JKR (Griffith like) conditions\nwhich involve singular pressure and shear, as well as in full general cohesive\nmodels. We offer a rigorous thermodynamics calculation, which suggests in fact\nthere is no qualitative contrast but a very close quantitative agreement, with\nprevious theories. Actually, the model predicts an even stronger reduction of\ncontact area than predicted by Savkoor and Briggs, contrary to experimental\nobservations, so would certainly require some adjustements to consider\ndissipative effects.",
        "positive": "Self-assembly of Colloidal Superballs Under Spherical Confinement of a\n  Drying Droplet: Understanding the relationship between colloidal building block shape and\nself-assembled material structure is important for the development of novel\nmaterials by self-assembly. In this regard, colloidal superballs are unique\nbuilding blocks because their shape can smoothly transition between spherical\nand cubic. Assembly of colloidal superballs under spherical confinement results\nin macroscopic clusters with ordered internal structure. By utilizing Small\nAngle X-Ray Scattering (SAXS), we probe the internal structure of colloidal\nsuperball dispersion droplets during confinement. We observe and identify four\ndistinct drying regimes that arise during compression via evaporating droplets,\nand we track the development of the assembled macrostructure. As the superballs\nassemble, we found that they arrange into the predicted paracrystalline,\nrhombohedral C1-lattice that varies by the constituent superballs' shape. This\nprovides insights in the behavior between confinement and particle shape that\ncan be applied in the development of new functional materials."
    },
    {
        "anchor": "The Effective Interfacial Tensions between Pure Liquids and Rough\n  Solids: A Coarse-Grained Simulation Study: The effective solid liquid interfacial tension (SL IFT) between pure liquids\nand rough solid surfaces is studied through coarse grained simulations. Using\nthe dissipative particle dynamics method, we design solid liquid interfaces,\nconfining a pure liquid between two explicit solid surfaces with different\nroughness degrees. The roughness of the solid phase was characterized by Wenzel\nroughness factor and the effective SL IFT ({\\gamma}_sl^') is reported as a\nfunction of it also. Two solid liquid systems differentiated from each other by\ntheir solid liquid repulsion strength are studied to measure the effects caused\nby the surface roughness on the calculation of {\\gamma}_sl^'. We found that the\nroughness produces changes in the structure of the liquid, which is observed in\nthe first layer of liquid near the solid. These changes are responsible for the\neffective SL IFT increase as surface roughness increases. Although there is a\npredominance of surface roughness in the calculation of {\\gamma}_sl^', it is\nfound that the effective SL IFT is directly proportional to the magnitude of\nthe solid liquid repulsion strength. The insights provided by these simulations\nsuggest that the increase of Wenzel roughness factor is a direct consequence of\nthe increase in surface area due to the vertical deviations measured in the\ntopography. This, in turn, produces an increase in the number of effective\nsolid liquid interactions between particles, eventually yielding significant\nchanges in the local values of the normal and tangential components of the\npressure tensor.",
        "positive": "Glassy phases of the Gaussian Core Model: We present results from molecular dynamics simulations exploring the\nsupercooled dynamics of the Gaussian Core Model in the low- and\nintermediate-density regimes. In particular, we discuss the transition from the\nlow-density hard-sphere-like glassy dynamics to the high-density one. The\ndynamics at low densities is well described by the caging mechanism, giving\nrise to intermittent dynamics. At high densities, the particles undergo a more\ncontinuous motion in which the concept of cage loses its meaning. We elaborate\non the idea that these different supercooled dynamics are in fact the\nprecursors of two different glass states."
    },
    {
        "anchor": "Glassy relaxation in de Vries smectic liquid crystal consisting of\n  bent-core molecules: We report the experimental investigations on a liquid crystal comprised of\nthiophene-based achiral bent-core banana shaped molecules. The results reveal\nthe presence of a short range nematic phase at high temperatures and a\nlong-range SmA phase at lower temperatures, which transits to a SmC phase on\nfurther cooling the sample. Practically no layer contraction was observed\nacross the SmA to SmC transition, indicating the de Vries nature of the SmA\nphase. Interestingly, the crystallization does not occur on cooling the sample\ntill 223 K; instead, a glass transition at 271 K was observed. The dielectric\nspectroscopy studies carried out on the sample reveal the presence of a\ndielectric mode whose relaxation process is of the Cole-Cole type. The\nrelaxation frequency of the mode was found to drop rapidly with decreasing\ntemperature, further confirming the glassy behavior. The variation of\nrelaxation frequency with temperature follows the Vogel-Fulcher-Tammann\nequation indicating the fragile glassy nature of the sample.",
        "positive": "Influence of solvent quality on effective pair potentials between\n  polymers in solution: Solutions of interacting linear polymers are mapped onto a system of ``soft''\nspherical particles interacting via an effective pair potential. This\ncoarse-graining reduces the individual monomer-level description to a problem\ninvolving only the centers of mass (CM) of the polymer coils. The effective\npair potentials are derived by inverting the CM pair distribution function,\ngenerated in Monte Carlo simulations, using the hypernetted chain (HNC)\nclosure. The method, previously devised for the self-avoiding walk model of\npolymers in good solvent, is extended to the case of polymers in solvents of\nvariable quality by adding a finite nearest-neighbor monomer-monomer attraction\nto the previous model and varying the temperature. The resulting effective pair\npotential is found to depend strongly on temperature and polymer concentration.\nAt low concentration the effective interaction becomes increasingly attractive\nas the temperature decreases, eventually violating thermodynamic stability\ncriteria. However, as polymer concentration is increased at fixed temperature,\nthe effective interaction reverts to mostly repulsive behavior. These issues\nhelp illustrate some fundamental difficulties encountered when coarse-graining\ncomplex systems via effective pair potentials."
    },
    {
        "anchor": "Evanescent Gels: Competition Between Sticker Dynamics and Single Chain\n  Relaxation: Solutions of polymer chains are modelled using non-equilibrium Brownian\ndynamics simulations, with physically associative beads which form reversible\ncrosslinks to establish a system-spanning physical gel network. Rheological\nproperties such as the zero-shear-rate viscosity and relaxation modulus are\ninvestigated systematically as functions of polymer concentration and the\nbinding energy between associative sites. It is shown that a system-spanning\nnetwork can form regardless of binding energy at sufficiently high\nconcentration. However, the contribution to the stress sustained by this\nphysical network can decay faster than other relaxation processes, even single\nchain relaxations. If the polymer relaxation time scales overlap with\nshort-lived associations, the mechanical response of a gel becomes\n``evanescent'', decaying before it can be rheologically observed, even though\nthe network is instantaneously mechanically rigid. In our simulations, the\nconcentration of elastically active chains and the dynamic modulii are computed\nindependently. This makes it possible to combine structural and rheological\ninformation to identify the concentration at which the sol-gel transition\noccurs as a function of binding energy. Further, it is shown that the\ncompetition of scales between the sticker dissociation time and the\nsingle-polymer relaxation time determines if the gel is in the evanescent\nregime.",
        "positive": "Black soliton in a quasi-one-dimensional trapped fermion-fermion mixture: Employing a time-dependent mean-field-hydrodynamic model we study the\ngeneration of black solitons in a degenerate fermion-fermion mixture in a\ncigar-shaped geometry using variational and numerical solutions. The black\nsoliton is found to be the first stationary vibrational excitation of the\nsystem and is considered to be a nonlinear continuation of the vibrational\nexcitation of the harmonic oscillator state. We illustrate the stationary\nnature of the black soliton, by studying different perturbations on it after\nits formation."
    },
    {
        "anchor": "Chemical herding as a multiplicative factor for top-down manipulation of\n  colloids: Colloidal particles can create reconfigurable nanomaterials, with\napplications such as color-changing, self-repairing, and self-regulating\nmaterials and reconfigurable drug delivery systems. However, top-down methods\nfor manipulating colloids are limited in the scale they can control. We\nconsider here a new method for using chemical reactions to multiply the effects\nof existing top-down colloidal manipulation methods to arrange large numbers of\ncolloids with single-particle precision, which we refer to as chemical herding.\nUsing simulation-based methods, we show that if a set of chemically active\ncolloids (herders) can be steered using external forces (i.e. electrophoretic,\ndielectrophoretic, magnetic, or optical forces), then a larger set of colloids\n(followers) that move in response to the chemical gradients produced by the\nherders can be steered using the control algorithms given in this paper. We\nalso derive bounds that predict the maximum number of particles that can be\nsteered in this way, and we illustrate the effectiveness of this approach using\nBrownian dynamics simulations. Based on the theoretical results and\nsimulations, we conclude that chemical herding is a viable method for\nmultiplying the effects of existing colloidal manipulation methods to create\nuseful structures and materials.",
        "positive": "Triplet forces between star polymers: We analyze the effective triplet interactions between the centers of star\npolymers in a good solvent. Using an analytical short distance expansion\ninspired by scaling theory, we deduce that the triplet part of the three-star\nforce is attractive but only 11% of the pairwise part even for a close approach\nof three star polymers. We have also performed extensive computer simulations\nfor different arm numbers to extract the effective triplet force. The\nsimulation data show good correspondence with the theoretical predictions. Our\nresults justify the effective pair potential picture even beyond the star\npolymer overlap concentration."
    },
    {
        "anchor": "Slow kinks in dissipative kirigami: Mechanical waves that travel without inertia are often encountered in nature\n-- e.g. motion of plants -- yet such waves remain rare in synthetic materials.\nHere, we discover the emergence of slow kinks in overdamped metamaterials and\nwe show that they can be used for applications such as sensing, dynamic pattern\nmorphing and transport of objects. To do this, we create dissipative kirigami\nwith suitably patterned viscoelasticity. These kirigami shape-change into\ndifferent textures depending on how fast they are stretched. We find that if we\nstretch fast and wait, the viscoelastic kirigami can eventually snap from one\ntexture to another. Crucially, such a snapping instability occurs in a sequence\nand a travelling overdamped kink emerges. We demonstrate that such kink\nunderpins dynamic shape morphing in 2D kirigami and can be used to transport\nobjects. Our results open avenues for the use of slow kinks in metamaterials,\nsoft robotics and biomimicry.",
        "positive": "Star Polymers Confined in a Nanoslit: A Simulation Test of Scaling and\n  Self-Consistent Field Theories: The free energy cost of confining a star polymer where $f$ flexible polymer\nchains containing $N$ monomeric units are tethered to a central unit in a slit\nwith two parallel repulsive walls a distance $D$ apart is considered, for good\nsolvent conditions. Also the parallel and perpendicular components of the\ngyration radius of the star polymer, and the monomer density profile across the\nslit are obtained. Theoretical descriptions via Flory theory and scaling\ntreatments are outlined, and compared to numerical self-consistent field\ncalculations (applying the Scheutjens-Fleer lattice theory) and to Molecular\nDynamics results for a bead-spring model. It is shown that Flory theory and\nself-consistent field (SCF) theory yield the correct scaling of the parallel\nlinear dimension of the star with $N$, $f$ and $D$, but cannot be used for\nestimating the free energy cost reliably. We demonstrate that the same problem\noccurs already for the confinement of chains in cylindrical tubes. We also\nbriefly discuss the problem of a free or grafted star polymer interacting with\na single wall, and show that the dependence of confining force on the\nfunctionality of the star is different for a star confined in a nanoslit and a\nstar interacting with a single wall, which is due to the absence of a symmetry\nplane in the latter case."
    },
    {
        "anchor": "Conformal Elasticity of Mechanism-Based Metamaterials: Deformations of conventional solids are described via elasticity, a classical\nfield theory whose form is constrained by translational and rotational\nsymmetries. However, flexible metamaterials often contain an additional\napproximate symmetry due to the presence of a designer soft strain pathway.\nHere we show that low energy deformations of designer dilational metamaterials\nwill be governed by a novel field theory, conformal elasticity, in which the\nnonuniform, nonlinear deformations observed under generic loads correspond with\nthe well-studied conformal maps. We validate this approach using experiments\nand finite element simulations and further show that such systems obey a\nholographic bulk-boundary principle, which enables an unprecedented analytic\nmethod to predict and control nonuniform, nonlinear deformations. This work\nboth presents a novel method of precise deformation control and demonstrates a\ngeneral principle in which mechanisms can generate special classes of soft\ndeformations.",
        "positive": "Dynamical Behaviour in the Nonlinear Rheology of Surfactant Solutions: Several surfactant molecules self-assemble in solution to form long, flexible\nwormlike micelles which get entangled with each other, leading to viscoelastic\ngel phases. We discuss our recent work on the rheology of such a gel formed in\nthe dilute aqueous solutions of a surfactant CTAT. In the linear rheology\nregime, the storage modulus $G^{\\prime}(\\omega)$ and loss modulus\n$G^{\\prime\\prime}(\\omega)$ have been measured over a wide frequency range. In\nthe nonlinear regime, the shear stress $\\sigma$ shows a plateau as a function\nof the shear rate $\\dot\\gamma$ above a certain cutoff shear rate\n$\\dot\\gamma_c$. Under controlled shear rate conditions in the plateau regime,\nthe shear stress and the first normal stress difference show oscillatory\ntime-dependence. The analysis of the measured time series of shear stress and\nnormal stress has been done using several methods incorporating state space\nreconstruction by embedding of time delay vectors.The analysis shows the\nexistence of a finite correlation dimension and a positive Lyapunov exponent,\nunambiguously implying that the dynamics of the observed mechanical instability\ncan be described by that of a dynamical system with a strange attractor of\ndimension varying from 2.4 to 2.9."
    },
    {
        "anchor": "Elastically coupled molecular motors: We study the influence of filament elasticity on the motion of collective\nmolecular motors. It is found that for a backbone flexibility exceeding a\ncharacteristic value (motor stiffness divided through the mean displacement\nbetween attached motors), the ability of motors to produce force reduces as\ncompared to rigidly coupled motors, while the maximum velocity remains\nunchanged. The force-velocity-relation in two different analytic approximations\nis calculated and compared with Monte-Carlo simulations. Finally, we extend our\nmodel by introducing motors with a strain-dependent detachment rate. A\nremarkable crossover from the nearly hyperbolic shape of the Hill curve for\nstiff backbones to a linear force-velocity relation for very elastic backbones\nis found. With realistic model parameters we show that the backbone flexibility\nplays no role under physiological conditions in muscles, but it should be\nobservable in certain in vitro assays.",
        "positive": "Exact curvilinear diffusion coefficients in the repton model: The Rubinstein-Duke or repton model is one of the simplest lattice model of\nreptation for the diffusion of a polymer in a gel or a melt. Recently, a\nslightly modified model with hardcore interactions between the reptons has been\nintroduced. The curvilinear diffusion coefficients of both models are exactly\ndetermined for all chain lengths. The case of periodic boundary conditions is\nalso considered."
    },
    {
        "anchor": "Investigation of shear banding in three-dimensional foams: We study the steady flow properties of different three-dimensional aqueous\nfoams in a wide gap Couette geometry. From local velocity measurements through\nMagnetic Resonance Imaging techniques and from viscosity bifurcation\nexperiments, we find that these foams do not exhibit any observable signature\nof shear banding. This contrasts with two previous results (Rodts et al.,\nEurophys. Lett., 69 (2005) 636 and Da Cruz et al., Phys. Rev. E, 66 (2002)\n051305); we discuss possible reasons for this dicrepancy. Moreover, the foams\nwe studied undergo steady flow for shear rates well below the critical shear\nrate recently predicted (Denkov et al., Phys. Rev. Lett., 103 (2009) 118302).\nLocal measurements of the constitutive law finally show that these foams behave\nas simple Herschel-Bulkley yield stress fluids.",
        "positive": "Particle self-assembly on soft elastic shells: We use numerical simulations to show how noninteracting hard particles\nbinding to a deformable elastic shell may self-assemble into a variety of\nlinear patterns. This is a result of the nontrivial elastic response to\ndeformations of shells. The morphology of the patterns can be controlled by the\nmechanical properties of the surface, and can be fine-tuned by varying the\nbinding energy of the particles. We also repeat our calculations for a fully\nflexible chain and find that the chain conformations follow patterns similar to\nthose formed by the nanoparticles under analogous conditions. We propose a\nsimple way of understanding and sorting the different structures and relate it\nto the underlying shape transition of the shell. Finally, we discuss the\nimplications of our results."
    },
    {
        "anchor": "Topological Inclusions in 2D Smectic-C Films: In thin films of smectic-C liquid crystals, localized regions containing\nadditional smectic layers form circular inclusions that carry a topological\ncharge. Such inclusions nucleate a companion topological defect. These\ninclusion-defect pairs are modeled as topological dipoles within the context of\na one-coupling constant approximation to the 2D Frank free energy. Deviations\nof the dipole direction from a preferred orientation cause the dipoles to\nacquire a logarithmic charge. Thermal fluctuations of the dipole direction are\ncalculated and found to be large, scaling as the logarithm of the system size.\nIn addition to dipole-dipole interactions arising from the topological charges,\nwe also find that the thermal fluctuations of the dipole directions are coupled\nthrough a preference for global charge neutrality of the logarithmic charges.",
        "positive": "Self-assembly of complex structures in colloid-polymer mixtures: If particles interact according to isotropic pair potentials that favor\nmultiple length scales, in principle a large variety of different complex\nstructures can be achieved by self-assembly. We present, motivate, and discuss\na conjecture for the occurrence of non-trivial (i.e., non-triangular) orderings\nbased on newly-introduced enthalpy-like pair potentials, the capability of\nwhich we demonstrate for the specific example of colloid-polymer mixtures. Upon\nexamining the phase behavior of two-dimensional colloid-polymer mixtures, which\ncan also be realized in experiments, we observe that non-trivial structures\nonly occur in the vicinity of selected densities where triangular ordering is\nsuppressed by the pair potential. Close to these densities, a large number of\ndifferent phases self-assemble that correspond to tilings containing\ntriangular, rhombic, square, hexagonal, and pentagonal tiles, and including\nsome of the Archimedean tilings. We obtain the ground-state energies by\nminimizing the corresponding lattice sums with respect to particle positions in\na unit cell as well as cell geometry and verify the occurrence of selected\nphases at finite temperatures by using Brownian Dynamics simulations. All\nreported phases should be accessible in experiments and, in addition, our work\nprovides a manual on how to find the regions of non-trivial phases in parameter\nspace for complex pair interactions in general."
    },
    {
        "anchor": "Influence of the solid fraction on the clogging by bridging of\n  suspensions in constricted channels: Clogging can occur whenever a suspension of particles flows through a\nconfined system. The formation of clogs is often correlated to a reduction in\nthe cross-section of the channel. In this study, we consider the clogging by\nbridging, i.e., through the formation of a stable arch of particles at a\nconstriction that hinders the transport of particles downstream of the clog. To\ncharacterize the role of the volume fraction of the suspension on the clogging\ndynamics, we study the flow of particulate suspensions through 3D-printed\nmillifluidic devices. We systematically characterize the bridging of\nnon-Brownian particles in a quasi-bidimensional system in which we directly\nvisualize and track the particles as they flow and form arches at a\nconstriction. We report the conditions for clogging by bridging when varying\nthe constriction width to particle diameter ratio for different concentrations\nof the particles in suspension. We then discuss our results using a stochastic\nmodel to rationalize the influence of solid fraction on the probability of\nclogging. Understanding the mechanisms and conditions of clog formation is an\nimportant step for optimizing engineering design and developing more reliable\ndispensing systems.",
        "positive": "Phase Coexistence and Edge Currents in the Chiral Lennard-Jones Fluid: We study a model chiral fluid in two dimensions composed of Brownian disks\ninteracting via a Lennard-Jones potential and a non-conservative transverse\nforce, mimicking colloids spinning at a rate $\\omega$. The system exhibits a\nphase separation between a chiral liquid and a dilute gas phase that can be\ncharacterized using a thermodynamic framework. We compute the equations of\nstate and show that the surface tension controls interface corrections to the\ncoexisting pressure predicted from the equal-area construction. Transverse\nforces increase surface tension and generate edge currents at the liquid-gas\ninterface. The analysis of these currents shows that the rotational viscosity\nintroduced in chiral hydrodynamics is consistent with microscopic bulk\nmechanical measurements. Chirality can also break the solid phase, giving rise\nto a dense fluid made of rotating hexatic patches. Our work paves the way for\nthe development of the statistical mechanics of chiral particles assemblies."
    },
    {
        "anchor": "Axial Particle Diffusion in Rotating Cylinders: We study the interface dynamics of a binary particle mixture in a rotating\ncylinder numerically. By considering only the particle motion in axial\ndirection, it is shown that the initial dynamics can be well described by a\none-dimensional diffusion process. This allows us to calculate a macroscopic\ndiffusion constant and we study its dependence on the inter-particle friction\ncoefficient, the rotation speed of the cylinder and the density ratio of the\ntwo components. It is found that radial segregation reduces the drift velocity\nof the interface. We then perform a microscopic calculation of the diffusion\ncoefficient and investigate its dependence on the position along the cylinder\naxis and the density ratio of the two particle components. The latter\ndependence can be explained by looking at the different hydrostatic pressures\nof the two particle components at the interface. We find that the\nmicroscopically calculated diffusion coefficient agrees well with the value\nfrom the macroscopic definition when taken in the middle of the cylinder.",
        "positive": "Comment on the characterization of local structure in an inhomogeneous\n  liquid: The search for local structures within a disordered medium has led to\nproposals of several methods for probing transient short-range symmetry in a\nhomogeneous mono-atomic liquid. We offer a comparison of different\ncharacterizations of such local structure in an in-homogeneous liquid. We\nsimulate the interfaces between a Lennard-Jones liquid and (i) a flat\nLennard-Jones wall, (ii) a wall of face-centered cubic-packed Lennard-Jones\nparticles, and (iii) a Lennard-Jones vapor. The interface density distributions\nin cases (i) and (ii) have oscillations extending several particle diameters\ninto the bulk liquid, while that in case (iii) the interface density\ndistribution monotonically decays from the bulk liquid to the vapor. We search\nfor transient ordered fluctuations, which we identify with local ordered\nstructures, using the Aperture Cross Correlation Function of the system. We\nfind that only particles in the FCC-liquid interface that are in the two layers\nclosest to the FCC surface exhibit preferred four-fold symmetry. Furthermore,\nthe absence of three- or five-fold symmetry peaks in the Aperture Cross\nCorrelation Function of the liquid-vapor interface yields a different picture\nof that interface than derived from the high density of bi-pyramidal clusters\nfound in the Topological Cluster Classification study (Molecular Physics, 109\n(7-10), 1393-1402 (2011)). While the Aperture Cross Correlation Function\nresults need not be viewed as contradictory with the Topological Cluster\nClassification results, we argue the advantages of using the former to\ncharacterize transient ordered fluctuations as being both experimentally\naccessible in favorable cases and not reliant on a list of structures."
    },
    {
        "anchor": "Internal stress as a link between macroscale and mesoscale mechanics: The internal (or residual) stress is among the key notions to describe the\nstate of the systems far from equilibrium. Such stress is invisible on the\nmacroscopic scale where the system is regarded as a blackbox. Yet\nnonequilibrium macroscopic operations allow to create and observe the internal\nstress. We present in this lecture some examples of the internal stress and its\noperations. We describe the memory effect in some detail, the process in which\nthe history of past operations is recalled through the relaxation of internal\nstress.",
        "positive": "Spatial organization of slit-confined melts of ring polymers with\n  non-conserved topology: A lattice Monte Carlo study: We present Monte Carlo computer simulations for melts of semiflexible\nrandomly knotted and randomly concatenated ring polymers on the fcc lattice and\nin slit confinement. Through systematic variation of the slit width at fixed\nmelt density, we first explore the influence of confinement on single-chain\nconformations and inter-chain interactions. We demonstrate that confinement\nmakes chains globally larger and more elongated, while enhancing both contacts\nand knottedness propensities. As for multi-chain properties, we show that\nring-ring contacts decrease with the confinement, yet neighbouring rings are\nmore overlapped as confinement grows. These aspects are reflected on the\ndecrease of the links formation between pairs of rings. The results suggest\nthat confinement can be used to fine-tune the mechanical properties of the\npolymer network. In particular, confinement biases the synthesis of networks\nthat are softer to mechanical stress. Finally, in connection with a previous\nstudy of us and recent simulations on two-dimensional polymer melts, our\nfindings suggest that entanglements in polymer melts arise from pairwise\nring-ring links alone."
    },
    {
        "anchor": "Perimeter Length and Form Factor of Two-Dimensional Polymer Melts: Self-avoiding polymers in two-dimensional ($d=2$) melts are known to adopt\ncompact configurations of typical size $R(N) \\sim N^{1/d}$ with $N$ being the\nchain length. Using molecular dynamics simulations we show that the irregular\nshapes of these chains are characterized by a perimeter length $L(N) \\sim\nR(N)^{\\dpm}$ of fractal dimension $\\dpm = d-\\Theta_2 =5/4$ with $\\Theta_2=3/4$\nbeing a well-known contact exponent. Due to the self-similar structure of the\nchains, compactness and perimeter fractality repeat for subchains of all\narc-lengths $s$ down to a few monomers. The Kratky representation of the\nintramolecular form factor $F(q)$ reveals a strong non-monotonous behavior with\n$q^2F(q) \\sim 1/(qN^{1/d})^{\\Theta_2}$ in the intermediate regime of the\nwavevector $q$. Measuring the scattering of labeled subchains %($s F(q) \\sim\nL(s)$) the form factor may allow to test our predictions in real experiments.",
        "positive": "Liquid meniscus friction on a wet plate: Bubbles, lamellae and foams: Many microfluidics devices, coating processes or diphasic flows involve the\nmotion of a liquid meniscus on a wet wall. This motion induces a specific\nviscous force, that exhibits a non-linear dependency in the meniscus velocity.\nWe propose a review of the theoretical and experimental work made on this\nviscous force, for simple interfacial properties. The interface is indeed\nassumed either perfectly compressible (mobile interface) or perfectly\nincompressible (rigid interface). We show that, in the second case, the viscous\nforce exerted by the wall on the meniscus is a combination of two power laws,\nscaling like $Ca^{1/3}$ and $Ca^{2/3}$, with $Ca$ the capillary number. We\nprovide a prediction for the stress exerted on a foam sliding on a wet solid\nand compare it with experimental data, for the incompressible case."
    },
    {
        "anchor": "A variational formulation of electrostatics in a medium with spatially\n  varying dielectric permittivity: In biological and synthetic materials, many important processes involve\ncharges that are present in a medium with spatially varying dielectric\npermittivity. To accurately understand the role of electrostatic interactions\nin such systems, it is important to take into account the spatial dependence of\nthe permittivity of the medium. However, due to the ensuing theoretical and\ncomputational challenges, this inhomogeneous dielectric response of the medium\nis often ignored or excessively simplified. We develop a variational\nformulation of electrostatics to accurately investigate systems that exhibit\nthis inhomogeneous dielectric response. Our formulation is based on a true\nenergy functional of the polarization charge density. The defining\ncharacteristic of a true energy functional is that at its minimum it evaluates\nto the actual value of the energy; this is a feature not found in many commonly\nused electrostatic functionals. We explore in detail the charged systems that\nexhibit sharp discontinuous change in dielectric permittivity, and we show that\nfor this case our functional reduces to a functional of only the surface\npolarization charge density. We apply this reduced functional to study model\nproblems for which analytical solutions are well known. We demonstrate, in\naddition, that the functional has many properties that make it ideal for use in\nmolecular dynamics simulations.",
        "positive": "Textural equilibrium melt geometries around tetrakaidecahedral grains: In textural equilibrium, partially molten materials minimise the total\nsurface energy bound up in grain boundaries and grain-melt interfaces. Here,\nnumerical calculations of such textural equilibrium geometries are presented\nfor a space-filling tessellation of grains with a tetrakaidecahedral (truncated\noctahedral) unit cell. Two parameters determine the nature of the geometries:\nthe porosity and the dihedral angle. A variety of distinct melt topologies\noccur for different combinations of these two parameters, and the boundaries\nbetween different topologies has been determined. For small dihedral angles,\nwetting of grain boundaries occurs once the porosity has exceeded 11%. An\nexhaustive account is given of the main properties of the geometries: their\nenergy, pressure, mean curvature, contiguity, and areas on cross-sections and\nfaces. Their effective permeabilities have been calculated, and demonstrate a\ntransition between a quadratic variation with porosity at low porosities to a\ncubic variation at high porosities."
    },
    {
        "anchor": "Sedimentation stacking diagrams of binary mixtures of thick and thin\n  hard rods: We use Onsager theory and the local density approximation to study\nsedimentation-diffusion equilibrium density profiles of binary mixtures of\nthick and thin hard rods. We construct stacking diagrams for three diameter\nratios, and find that even a simple spindle-shaped phase diagram with only\nisotropic-nematic demixing can lead to counter-intuitive stacking sequences\nsuch as an isotropic phase sandwiched between two nematic phases. For the most\ncomplex phase diagram considered here, we find sixteen distinct stacking\nsequences, including several with five sedimented layers. By adding\nsedimentation paths to composition-pressure and density-density phase diagrams\nand calculating density and composition profiles, we show that conclusions\nabout bulk phase diagrams of binary mixtures on the basis of\nsedimentation-diffusion equilibria should be drawn warily.",
        "positive": "Creep and drainage in the fast destabilization of emulsions Creep and\n  drainage in the fast destabilization of emulsions: The destabilization of emulsions is important for many applications but\nremains incompletely understood. We perform squeeze flow measurements on\noil-in-water emulsions, finding that the spontaneous destabilization of\nemulsions is generally very slow under normal conditions, with a characteristic\ntime scale given by the drainage of the continuous phase and the coalescence of\nthe dispersed phase. We show that if the emulsion is compressed between two\nplates, the destabilization can be sped up significantly; on the one hand, the\ndrainage is faster due to the application of the squeezing force. On the other\nhand, creep processes lead to rearrangements that also contribute to the\ndestabilization."
    },
    {
        "anchor": "Calorimetric glass transition explained by hierarchical dynamic\n  facilitation: The glass transition refers to the non-equilibrium process by which an\nequilibrium liquid is transformed to a non-equilibrium disordered solid, or\nvice versa. Associated response functions, such as heat capacities, are\nmarkedly different on cooling than on heating, and the response to melting a\nglass depends markedly on the cooling protocol by which the glass was formed.\nThis paper shows how this irreversible behavior can be interpreted\nquantitatively in terms of an East-model picture of localized excitations (or\nsoft spots) in which molecules can move with a specific direction, and from\nwhich excitations with the same directionality of motion can appear or\ndisappear in adjacent regions. As a result of this facilitated dynamics,\nexcitations become correlated in a hierarchical fashion. These correlations are\nmanifested in the dynamic heterogeneity of the supercooled liquid phase. While\nequilibrium thermodynamics is virtually featureless, a non-equilibrium glass\nphase emerges when the model is driven out of equilibrium with a finite cooling\nrate. The correlation length of this emergent phase is large and increases with\ndecreasing cooling rate. A spatially and temporally resolved fictive\ntemperature encodes memory of its preparation. Parameters characterizing the\nmodel can be determined from reversible transport data, and with these\nparameters, predictions of the model agree well with irreversible differential\nscanning calorimetry.",
        "positive": "Towards a general(ized) shear thickening rheology of wet granular\n  materials under small pressure: We study the rheology of dry and wet granular materials in the steady\nquasistatic regime using the Discrete Element Method (DEM) in a split-bottom\nring shear cell with focus on the macroscopic friction. The aim of our study is\nto understand the local rheology of bulk flow at various positions in the shear\nband, where the system is in critical state. The general(ized) rheology has\nfour dimensionless control parameters that relate the time scales of five\nsignificant phenomena, namely, the time scales related to confining pressure\n$t_p$, shear rate $t_{\\dot{\\gamma}}$, particle stiffness $t_k$, gravity $t_g$\nand cohesion $t_c$, respectively. We show that those phenomena collectively\ncontribute to the rheology as multiplicative correction functions.\n  While $t_{\\dot{\\gamma}}$ is large and thus little important for most of the\ndata studied, it can increase the friction of flow in critical state, where the\nshear gradients are high. $t_g$ and $t_k$ are comparable to $t_p$ in the bulk,\nbut become more or less dominant relative to $t_p$ at the extremes of the free\nsurface and deep inside the bulk, respectively.\n  We also measure the effect of strong wet cohesion on the flow rheology, as\nquantified by decreasing $t_c$. Furthermore, the proposed rheological model\npredicts well the shear thinning behavior both in the bulk and near the free\nsurface; shear thinning develops to shear thickening near the free surface with\nincreasing cohesion."
    },
    {
        "anchor": "Understanding reversible looping kinetics of a long polymer molecule in\n  solution. Exact solution for two state model with delta function coupling: In this paper, the looping kinetics of a long polymer chain in solution has\nbeen investigated by using two state model, where one state represents open\nchain polymer molecule and the other represents closed chain polymer molecule.\nThe dynamics of end-to end distance of both open chain and closed chain polymer\nis represented by a Smoluchowski-like equation for a single particle under two\ndifferent harmonic potentials. The coupling between these two potentials are\nassumed to be a Dirac Delta function in our model. We evaluate two rate\nconstants, the long term and the average rate constant. We have also\nincorporated the effect of all other chemical reactions involving at least one\nend of the open chain polymer molecule - on rate of end-to-end loop formation.\nThe closed chain polymer molecule can be converted to a open chain molecule by\nbreaking of any bond - the effect of this reaction on the rate of end-to-end\nloop formation is also considered in our model.",
        "positive": "Phase-separation of miscible liquids in a centrifuge: We show that a liquid mixture in the thermodynamically stable homogeneous\nphase can undergo a phase-separation transition when rotated at sufficiently\nhigh frequency $\\omega$. This phase-transition is different from the usual case\nwhere two liquids are immiscible or where the slow sedimentation process of one\ncomponent (e.g. a polymer) is accelerated due to centrifugation. For a binary\nmixture, the main coupling is due to a term $\\propto \\Delta\\rho(\\omega r)^2$,\nwhere $\\Delta\\rho$ is the difference between the two liquid densities and $r$\nthe distance from the rotation axis. Below the critical temperature there is a\ncritical rotation frequency $\\omega_c$, below which smooth density gradients\noccur. When $\\omega>\\omega_c$, we find a sharp interface between the low\ndensity liquid close to the center of the centrifuge and a high density liquid\nfar from the center. These findings may be relevant to various separation\nprocesses and to the control of chemical reactions, in particular their\nkinetics."
    },
    {
        "anchor": "From thermally activated to viscosity controlled fracture of biopolymer\n  hydrogels: We report on rate-dependent fracture energy measurements over three decades\nof steady crack velocities in alginate and gelatin hydrogels. We evidence that,\nirrespective of gel thermo-reversibility, thermally activated \"unzipping\" of\nthe non-covalent cross-link zones results in slow crack propagation, prevaling\nagainst the toughening effect of viscous solvent drag during chain pull-out,\nwhich becomes efficient above a few mm.s$^{-1}$. We extend a previous model\n[Baumberger {\\it et al.} Nature Materials, {\\bf 5}, 552 (2006)] to account for\nboth mechanisms, and estimate the microscopic unzipping rates.",
        "positive": "Effects of nanopore and fluid structure on anomalies and phase\n  transitions of confined core-softened fluids: We use Molecular Dynamics simulations to study how the nanopore and the fluid\nstructures affects the dynamic, thermodynamic and structural properties of a\nconfined anomalous fluid. The fluid is modeled using an effective pair\npotential derived from the ST4 atomistic model for water. This system exhibits\ndensity, structural and dynamical anomalies and the vapor-liquid and\nliquid-liquid critical points similar to the quantities observed in bulk water.\nThe confinement is modeled both by smooth and structured walls. The\ntemperatures of extremum density and diffusion for the confined fluid show a\nshift to lower values while the pressures move to higher amounts for both\nsmooth and structured confinement. In the case of smooth walls, the critical\npoints and the limit between fluid and amorphous phases show a non-monotonic\nchange in the temperatures and pressures when the the nanopore size is\nincrease. In the case of structured walls the pressures and temperatures of the\ncritical points varies monotonicaly with the porous size. Our results are\nexplained on basis of the competition between the different length scales of\nthe fluid and the wall-fluid interaction."
    },
    {
        "anchor": "The influence of periodic shear on structural relaxation and pore\n  redistribution in binary glasses: The evolution of porous structure, potential energy and local density in\nbinary glasses under oscillatory shear deformation is investigated using\nmolecular dynamics simulations. The porous glasses were initially prepared via\na rapid thermal quench from the liquid state across the glass transition and\nallowed to phase separate and solidify at constant volume, thus producing an\nextended porous network in an amorphous solid. We find that under periodic\nshear, the potential energy decreases over consecutive cycles due to gradual\nrearrangement of the glassy material, and the minimum of the potential energy\nafter thousands of shear cycles is lower at larger strain amplitudes. Moreover,\nwith increasing cycle number, the pore size distributions become more skewed\ntoward larger length scales where a distinct peak is developed and the peak\nintensity is enhanced at larger strain amplitudes. The numerical analysis of\nthe local density distribution functions demonstrates that cyclic loading leads\nto formation of higher density solid domains and homogenization of the glass\nphase with reduced density.",
        "positive": "Density-wave fronts on the brink of wet granular condensation: Density-wave fronts in a vibrofluidized wet granular layer undergoing a\ngas-liquid-like transition are investigated experimentally. The threshold of\nthe instability is governed by the amplitude of the vertical vibrations.\nFronts, which are curved into a spiral shape, propagate coherently along the\ncircular rim of the container with leading edges. They are stable beyond a\ncritical distance from the container center. Based on an analysis of the\nemerging time and length scales, we propose a model for the pattern formation\nby considering the competition between the time scale for the condensation of\nwet granular particles from a gas-like state and that of the energy injection\nresisting this process."
    },
    {
        "anchor": "Motion of a sphere in an oscillatory boundary layer: an optical tweezer\n  based study: The drag forces acting on a single polystyrene sphere in the vicinity of an\noscillating glass plate have been measured using an optical tweezer. The phase\nof the sphere is found to be a sensitive probe of the dynamics of the sphere.\nThe evolution of the phase from an inertially-coupled regime to a purely\nvelocity-coupled regime is explored. Moreover, the frequency dependent response\nis found to be characteristic of a damped oscillator with an effective inertia\nwhich is several orders of magnitude greater than that of the particle.",
        "positive": "Classical density functional theory, unconstrained crystallization, and\n  polymorphic behavior: While in principle, finite temperature density functional theory (ftDFT)\nshould be a powerful tool for the study of crystallization, in practice this\nhas not so far been the case. Progress has been hampered by technical problems\nwhich have plagued the study of the crystalline systems using the most\nsophisticated Fundamental Measure Theory models. In this paper, the reasons for\nthe difficulties are examined and it is proposed that the tensor functionals\ncurrently favored are in fact numerically unstable. By reverting to an older,\nmore heuristic model it is shown that all of the technical difficulties are\neliminated. Application to a Lennard-Jones fluid results in a demonstration of\npower of ftDFT to describe crystallization in a highly inhomogeneous system.\nFirst, we show that droplets attached to a slightly hydrophobic wall\ncrystallize spontaneously upon being quenched. The resulting crystallites are\nclearly faceted structures and are predominantly HCP structures. In contrast,\ndroplets in a fully periodic calculational cell remain stable to lower\ntemperatures and eventually show the same spontaneous localization of the\ndensity into 'atoms' but in an amorphous structure having many of the\nstructural charactersitics of a glass. A small change of the protocol leads, at\nthe same temperature, to the formation of crystals, this time with the FCC\nstructure typical of bulk Lennard-Jones solids. The FCC crystals have lower\nfree energy than the amorphous structures which in turn are more stable than\nthe liquid droplets. It is demonstrated that as the temperature is raised, the\nfree energy differences between the structures decreases until the solid\nclusters become less stable than the liquid droplets and spontaneously melt.\nThe presence of energy barriers separating the various structures is therefore\nclearly demonstrated."
    },
    {
        "anchor": "Size limit for particle-stabilized emulsion droplets under gravity: We demonstrate that emulsion droplets stabilized by interfacial particles\nbecome unstable beyond a size threshold set by gravity. This holds not only for\ncolloids but supra-colloidal glass beads, using which we directly observe the\nejection of particles near the droplet base. The number of particles acting\ntogether in these ejection events decreases with time until a stable acorn-like\nconfiguration is reached. Stability occurs when the weight of all remaining\nparticles is less than the interfacial binding force of one particle. We also\nshow the importance of the curvature of the droplet surface in promoting\nparticle ejection.",
        "positive": "Perception of Surface Defects by Active Exploration with a Biomimetic\n  Tactile Sensor: We investigate the transduction of tactile information during active\nexploration of finely textured surfaces using a novel tactile sensor mimicking\nthe human fingertip. The sensor has been designed by integrating a linear array\nof 10 micro-force sensors in an elastomer layer. We measure the sensors'\nresponse to the passage of elementary topographical features in the form of a\nsmall hole on a flat substrate. The response is found to strongly depend on the\nrelative location of the sensor with respect to the substrate/skin contact\nzone. This result can be quantitatively interpreted within the scope of a\nlinear model of mechanical transduction, taking into account both the intrinsic\nresponse of individual sensors and the context-dependent interfacial stress\nfield within the contact zone. Consequences on robotics of touch are briefly\ndiscussed."
    },
    {
        "anchor": "Anomalous diffusion in fractal globules: The fractal globule state is a popular model for describing chromatin packing\nin eukaryotic nuclei. Here we provide a scaling theory and dissipative particle\ndynamics (DPD) computer simulation for the thermal motion of monomers in the\nfractal globule state. Simulations starting from different entanglement-free\ninitial states show good convergence which provides evidence supporting the\nexistence of unique metastable fractal globule state. We show monomer motion in\nthis state to be sub-diffusive described by $\\langle X^2 (t)\\rangle \\sim\nt^{\\alpha_F}$ with $\\alpha_F$ close to 0.4. This result is in good agreement\nwith existing experimental data on the chromatin dynamics which makes an\nadditional argument in support of the fractal globule model of chromatin\npacking.",
        "positive": "Finite difference lattice Boltzmann model with flux limiters for\n  liquid-vapor systems: In this paper we apply a finite difference lattice Boltzmann model to study\nthe phase separation in a two-dimensional liquid-vapor system. Spurious\nnumerical effects in macroscopic equations are discussed and an appropriate\nnumerical scheme involving flux limiter techniques is proposed to minimize them\nand guarantee a better numerical stability at very low viscosity. The phase\nseparation kinetics is investigated and we find evidence of two different\ngrowth regimes depending on the value of the fluid viscosity as well as on the\nliquid-vapor ratio."
    },
    {
        "anchor": "Fluctuations in confined nematic liquid crystals in a regime of critical\n  wetting: Within the macroscopic Landau-de Gennes approach, we examine the Gaussian\nnormal mode fluctuations of semi-infinite nematic liquid crystals in a regime\nof critical wetting. It is argued that surface free-energy potentials that\nstrongly suppress the long-range nematic order favor the appearance of bound\nbiaxial nematic-director fluctuation modes, located in the domain occupied by\nthe thermodynamic phase wetting the wall. Instead, substrates enhancing the\norientational order promote the existence of uniaxial nematic-director local\nexcitations. Close to the phase coexistence temperature both types of local\nexciations are strongly softened as compared to their bulk counterparts and\nacquire characteristic cusplike low-energy spectra. These spectrum\npeculiarities are directly connected to the critical behavior of the mean-field\ninterface position and can provide a valuable insight on the nature of surface\ninteractions and critical wetting phenomena in nematic liquid crystals.\nPossible changes in the local director mode properties resulting from the\ncritical interface position fluctuations and order electricity effects are also\ndiscussed.",
        "positive": "Sorption of proteins to charged microgels: characterizing binding\n  isotherms and driving forces: We present a set of Langmuir binding models in which electrostatic\ncooperativity effects to protein sorption is incorporated in the spirit of\nGuoy-Chapman-Stern models, where the global substrate (microgel) charge state\nis modified by bound reactants (charged proteins). Application of this approach\nto lysozyme sorption to oppositely charged core-shell microgels allows us to\nextract the intrinsic, binding affinity of the protein to the gel, which is\nsalt-concentration independent and mostly hydrophobic in nature. The total\nbinding affinity is found to be mainly electrostatic in nature, changes many\norders of magnitude during the sorption process, and is significantly\ninfluenced by osmotic deswelling effects. The intrinsic binding affinity is\ndetermined to be about 7 kBT for our system. We additionally show that Langmuir\nbinding models and those based on excludedvolume interactions are formally\nequivalent for low to moderate protein packing, if the nature of the bound\nstate is consistently defined. Having appreciated this, a more quantitative\ninterpretation of binding isotherms in terms of separate physical interactions\nis possible in future for a wide variety of experimental approaches."
    },
    {
        "anchor": "How Sandcastles Fall: Capillary forces significantly affect the stability of sandpiles. We analyze\nthe stability of sandpiles with such forces, and find that the critical angle\nis unchanged in the limit of an infinitely large system; however, this angle is\nincreased for finite-sized systems. The failure occurs in the bulk of the\nsandpile rather than at the surface. This is related to a standard result in\nsoil mechanics. The increase in the critical angle is determined by the surface\nroughness of the particles, and exhibits three regimes as a function of the\nadded-fluid volume. Our theory is in qualitative agreement with the recent\nexperimental results of Hornbaker et al., although not with the interpretation\nthey make of these results.",
        "positive": "Burrowing dynamics of aquatic worms in soft sediments: We investigate the dynamics of \\textbf{\\textit{Lumbriculus variegatus}} in\nwater-saturated sediment beds to understand limbless locomotion in the benthic\nzone found at the bottom of lakes and oceans. These slender aquatic worms are\nobserved to perform elongation-contraction and transverse undulatory strokes in\nboth water-saturated sediments and water. Greater drag anisotropy in the\nsediment medium is observed to boost the burrowing speed of the worm compared\nto swimming in water with the same stroke using drag-assisted propulsion. We\ncapture the observed speeds by combining the calculated forms based on\nresistive-force theory of undulatory motion in viscous fluids and a dynamic\nanchor model of peristaltic motion in the sediments. Peristalsis is found to be\neffective for burrowing in non-cohesive sediments which fill in rapidly behind\nthe moving body inside the sediment bed. Whereas, the undulatory stroke is\nfound to be effective in water and in shallow sediment layers where anchoring\nis not possible to achieve peristaltic motion. We show that such dual strokes\noccur as well in the earthworm \\textbf{\\textit{Eisenia fetida}} which inhabit\nmoist sediments that are prone to flooding. Our analysis in terms of the\nrheology of the medium shows that the dual strokes are exploited by organisms\nto negotiate sediment beds that may be packed heterogeneously, and can be used\nby active intruders to move effectively from a fluid through the loose bed\nsurface layer which fluidize easily to the well-consolidated bed below."
    },
    {
        "anchor": "On the Kinetic Behavior and Folding Properties of an Off-Lattice\n  Heteropolymer Model: The kinetic behavior of a three-dimensional off-lattice heteropolymer model\nis studied in terms of the time dependence of the average mean-square\ndisplacement between configurations. It is found that at short time-scales\nsimilar behavior is obtained even for sequences with very different\nthermodynamic properties. Furthermore, the degree of cooperativity in the\nfolding process is examined by studying the residual number of degrees of\nfreedom, obtained from an eigenvalue analysis of the correlation matrix,\ncontributing to the structural fluctuations. In the compact state, a gradual\ndecrease in this effective number of degrees of freedom take place as the\ntemperature is lowered. This can be interpreted as an increasing asymmetry of\nthe energy landscape.",
        "positive": "Crossover from negative to positive shear rate dependence in granular\n  friction: We conduct an experiment on the frictional properties of granular matter over\na wide range of shear rate that covers both the quasistatic and the inertial\nregimes. We show that the friction coefficient exhibits negative shear-rate\ndependence in the quasistatic regime, whereas the shear-rate dependence is\npositive in the inertial regime. This crossover from negative to positive\nshear-rate dependence occurs at a critical inertial number. This is explained\nin terms of the competition between two physical processes, namely frictional\nhealing and anelasticity. We also find that the result does not depend on the\nshape of the grains and that the behavior in the inertial regime is\nquantitatively the same as that in numerical simulations."
    },
    {
        "anchor": "Improving the efficiency of organic light emitting diodes by use of a\n  diluted light-emitting layer: The use of a thin mixed layer consisting of an inert diluent material and a\nlight emitting material between the hole-transport layer and electron-transport\nlayer of organic light-emitting diodes leads to an increase in the external\nquantum efficiency. The efficiency improvement is highly dependent on the\nthickness of the diluted light-emitting layer and driving current. Significant\nimprovement seen at low current densities is explained in terms of effective\nhole confinement by the mixed layer while a modest decreases in efficiency at\nhigher current densities may be attributed to luminescence quenching at the\nhole-transport layer/inert diluents material interface. The phenomena are\ndemonstrated with three different inert diluents materials. A maximum external\nquantum efficiency improvement of about 40% is found for a diluted\nlight-emitting layer thickness between 40 {\\AA} and 60 {\\AA}.",
        "positive": "Tilt-induced clustering of cell adhesion proteins: Cell adhesion proteins are transmembrane proteins that bind cells to their\nenvironment. These proteins typically cluster into disk-shaped or linear\nstructures. Here we show that such clustering patterns spontaneously emerge\nwhen the protein sense the membrane deformation gradient, for example by\nreaching a lower-energy conformation when the membrane is tilted relative to\nthe underlying binding substrate. Increasing the strength of the membrane\ngradient-sensing mechanism first yields isolated disk-shaped clusters and then\nlong linear structures. Our theory is coherent with experimental estimates,\nsuggesting that a tilt-induced clustering mechanism is relevant in the context\nof cell adhesion proteins."
    },
    {
        "anchor": "Influence of humidity on granular packings with moving walls: A significant dependence on the relative humidity H for the apparent mass\n(Mapp) measured at the bottom of a granular packing inside a vertical tube in\nrelative motion is demonstrated experimentally. While the predictions of\nJanssen's model are verified for all values of H investigated (25%< H <80%),\nMapp increases with time towards a limiting value at high relative humidities\n(H>60%) but remains constant at lower ones (H=25%). The corresponding Janssen\nlength is nearly independent of the tube velocity for H>60% but decreases\nmarkedly for H=25%. Other differences are observed on the motion of individual\nbeads in the packing. For H=25%, they are almost motionless while the mean\nparticle fraction of the packing remains constant; for H>60% the bead motion is\nmuch more significant and the mean particle fraction decreases. The dependence\nof these results on the bead diameter and their interpretation in terms of the\ninfluence of capillary forces are discussed.",
        "positive": "Structure, thermodynamic properties, and phase diagrams of few colloids\n  confined in a spherical pore: We study a system of few colloids confined in a small spherical cavity by\nevent driven molecular dynamics simulations in the canonical ensemble. The\ncolloidal particles interact through a short range square-well potential, which\ntakes into account the basic elements of attraction and excluded-volume\nrepulsion of the interaction among colloids. We analyze the structural and\nthermodynamic properties of this few-body confined system in the framework of\nthe theory of inhomogeneous fluids. Pair correlation functions and density\nprofiles across the cavity are used to determine the structure of the system\nand the spatial characteristics of its inhomogeneities. Pressure on the walls,\ninternal energy and surface quantities such as surface tension and adsorption\nare also analyzed for the whole range of densities, temperatures and number of\nparticles considered. We have characterized the structure of systems from 2 to\n6 confined particles as function of density and temperature, identifying the\ndistinctive qualitative behaviors all over the thermodynamic plane $T-\\rho$ in\na few-particle equivalence to phase diagrams of macroscopic systems. Applying\nthe extended law of corresponding states the square well interaction is mapped\nto the Asakura-Oosawa model for colloid-polymer mixtures. We link explicitly\nthe temperature in the confined square-well fluid to the equivalent packing\nfraction of polymers in the Asakura-Oosawa model. Using this approach we study\nthe confined system of few colloids in a colloid-polymer mixture."
    },
    {
        "anchor": "Three-dimensional active turbulence in microswimmer suspensions:\n  simulations and modelling: Active turbulence is a paradigmatic and fascinating example of self-organized\nmotion at large scales occurring in active matter. We employ massive\nhydrodynamic simulations of suspensions of resolved model microswimmers to\ntackle the phenomenon in semi-diluted conditions at a mesoscopic level. We\nmeasure the kinetic energy spectrum and find that it decays as $k^{-3}$ over a\nrange of intermediate wavenumbers. The velocity distributions are of L\\'evy\ntype, a distinct difference with inertial turbulence. Furthermore, we propose a\nreduced order dynamical deterministic model for active turbulence, inspired to\nshell models for classical turbulence, whose numerical and analytical study\nconfirms the spectrum power-law observed in the simulations and reveals hints\nof a non-Gaussian, intermittent, physics of active turbulence. Direct numerical\nsimulations and modelling also agree in pointing to a phenomenological picture\nwhereby, in the absence of an energy cascade \\`a la Richardson forbidden by the\nlow Reynolds number regime, it is the coupling between fluid velocity gradients\nand bacterial orientation that gives rise to a multiscale dynamics.",
        "positive": "A constitutive model for simple shear of dense frictional suspensions: Discrete particle simulations are used to study the shear rheology of dense,\nstabilized, frictional particulate suspensions in a viscous liquid, toward\ndevelopment of a constitutive model for steady shear flows at arbitrary stress.\nThese suspensions undergo increasingly strong continuous shear thickening (CST)\nas solid volume fraction $\\phi$ increases above a critical volume fraction, and\ndiscontinuous shear thickening (DST) is observed for a range of $\\phi$. When\nstudied at controlled stress, the DST behavior is associated with non-monotonic\nflow curves of the steady-state stress as a function of shear rate. Recent\nstudies have related shear thickening to a transition between mostly lubricated\nto predominantly frictional contacts with the increase in stress. In this\nstudy, the behavior is simulated over a wide range of the dimensionless\nparameters $(\\phi,\\tilde{\\sigma}$, and $\\mu)$, with $\\tilde{\\sigma} =\n\\sigma/\\sigma_0$ the dimensionless shear stress and $\\mu$ the coefficient of\ninterparticle friction: the dimensional stress is $\\sigma$, and $\\sigma_0\n\\propto F_0/ a^2$, where $F_0$ is the magnitude of repulsive force at contact\nand $a$ is the particle radius. The data have been used to populate the model\nof the lubricated-to-frictional rheology of Wyart and Cates [Phys. Rev.\nLett.{\\bf 112}, 098302 (2014)], which is based on the concept of two viscosity\ndivergences or \\textquotedblleft jamming\\textquotedblright\\ points at volume\nfraction $\\phi_{\\rm J}^0 = \\phi_{\\rm rcp}$ (random close packing) for the\nlow-stress lubricated state, and at $\\phi_{\\rm J} (\\mu) < \\phi_{\\rm J}^0$ for\nany nonzero $\\mu$ in the frictional state; a generalization provides the normal\nstress response as well as the shear stress. A flow state map of this material\nis developed based on the simulation results."
    },
    {
        "anchor": "Diffusive dynamics of a model protein chain in solution: A Markov state model is a powerful tool that can be used to track the\nevolution of populations of configurations in an atomistic representation of a\nprotein. For a coarse-grained linear chain model with discontinuous\ninteractions, the transition rates among states that appear in the Markov model\nwhen the monomer dynamics is diffusive can be determined by computing the\nrelative entropy of states and their mean first passage times, quantities that\nare unchanged by the specification of the energies of the relevant states. In\nthis paper, we verify the folding dynamics described by a diffusive linear\nchain model of the crambin protein under three distinct solvent systems, each\ndiffering in complexity: a hard-sphere solvent, a solvent undergoing\nmulti-particle collision dynamics, and an implicit solvent model. The predicted\ntransition rates among configurations agree quantitatively with those observed\nin explicit molecular dynamics simulations for all three solvent models. These\nresults suggest that the local monomer-monomer interactions provide sufficient\nfriction for the monomer dynamics to be diffusive on timescales relevant to\nchanges in conformation. Factors such as structural ordering and dynamic\nhydrodynamic effects appear to have minimal influence on transition rates\nwithin the studied solvent densities.",
        "positive": "Nucleation patterns of polymer crystals analyzed by machine learning\n  models: We use machine learning algorithms to detect the crystalline phase in\nundercooled melts in molecular dynamics simulations. Our classification method\nis based on local conformation and environmental fingerprints of individual\nmonomers. In particular, we employ self-supervised auto-encoders to compress\nthe fingerprint information and a Gaussian mixture model to distinguish ordered\nstates from disordered ones. The resulting identification of crystalline\nmonomers agrees to a large extent with human-defined classifiers such as the\nstem-length-based classification scheme as developed in our previous work [C.\nLuo and J.-U. Sommer, Macromolecules 44 (2011), 1523], but does not require any\nforeknowledge about the structure of semi-crystalline polymers. Because of its\nlocal sensitivity, the method allows the resolution of detailed time patterns\nof crystalline order before an apparent signature of the transition is visible\nin thermodynamic properties such as for the specific volume. At a\npre-transition point, we observe the highest crystallization efficiency using\nthe fraction of monomers being conserved in the crystalline phase as compared\nto the number of monomers joining that phase."
    },
    {
        "anchor": "Excluded Volume Induces Buckling in Optically Driven Colloidal Rings: In our combined experimental, theoretical and numerical work, we study the\nout of equilibrium deformations in a shrinking ring of optically trapped,\ninteracting colloidal particles. Steerable optical tweezers are used to confine\ndielectric microparticles along a circle of discrete harmonic potential wells,\nand to reduce the ring radius at a controlled quench speed. We show that\nexcluded-volume interactions are enough to induce particle sliding from their\nequilibrium positions and nonequilibrium zigzag roughening of the colloidal\nstructure. Our work unveils the underlying mechanism of interfacial deformation\nin radially driven microscopic discrete rings.",
        "positive": "A hybrid particle-continuum resolution method and its application to a\n  homopolymer solution: We discuss in detail a recently proposed hybrid particle-continuum scheme for\ncomplex fluids and evaluate it at the example of a confined homopolymer\nsolution in slit geometry. The hybrid scheme treats polymer chains near the\nimpenetrable walls as particles keeping the configuration details, and chains\nin the bulk region as continuous density fields. Polymers can switch\nresolutions on the fly, controlled by an inhomogeneous tuning function. By\nproperly choosing the tuning function, the representation of the system can be\nadjusted to reach an optimal balance between physical accuracy and\ncomputational efficiency. The hybrid simulation reproduces the results of a\nreference particle simulation and is significantly faster (about a factor of\n3.5 in our application example)."
    },
    {
        "anchor": "Strain hardening in bidisperse polymer glasses: Separating the roles of\n  chain orientation and interchain entanglement: The effects of entanglement and chain orientation on strain hardening in\nglassy polymers are separated by examining mixtures of chains with different\nlengths. Simulations show that the orientation of a molecule of a given chain\nlength is the same in monodisperse systems and bidisperse mixtures, even when\nentangled and unentangled chains are mixed. In addition, the stress in mixtures\nis equal to the weighted average of the stresses in monodisperse systems. These\nresults indicate that chains contribute independently to strain hardening, that\nchain orientation is determined by local interactions with the surrounding\nglass, and that entanglements play at most an indirect role in strain hardening\nin the range of strains typically studied. We discuss these results in the\ncontext of recent microscopic theories.",
        "positive": "Kinetics of the glass transition of fragile soft colloidal suspensions: Microscopic relaxation timescales are estimated from the autocorrelation\nfunctions obtained by dynamic light scattering experiments for Laponite\nsuspensions with different concentrations ($C_{L}$), added salt concentrations\n($C_{S}$) and temperatures ($T$). It has been shown in an earlier work [Soft\nMatter, 10, 3292-3300 (2014)] that the evolutions of relaxation timescales of\ncolloidal glasses can be compared with molecular glass formers by mapping the\nwaiting time ($t_{w}$) of the former with the inverse of thermodynamic\ntemperature ($1/T$) of the latter. In this work, the fragility parameter $D$,\nwhich signifies the deviation from Arrhenius behavior, is obtained from fits to\nthe time evolutions of the structural relaxation timescales. For the Laponite\nsuspensions studied in this work, $D$ is seen to be independent of $C_{L}$ and\n$C_{S}$, but is weakly dependent on $T$. Interestingly, the behavior of $D$\ncorroborates the behavior of fragility in molecular glass formers with respect\nto equivalent variables. Furthermore, the stretching exponent $\\beta$, which\nquantifies the width $w$ of the spectrum of structural relaxation timescales is\nseen to depend on $t_{w}$. A hypothetical Kauzmann time $t_{k}$, analogous to\nthe Kauzmann temperature for molecular glasses, is defined as the timescale at\nwhich $w$ diverges. Corresponding to the Vogel temperature defined for\nmolecular glasses, a hypothetical Vogel time $t^{\\infty}_{\\alpha}$ is also\ndefined as the time at which the structural relaxation time diverges.\nInterestingly, a correlation is observed between $t_{k}$ and\n$t^{\\infty}_{\\alpha}$, which is remarkably similar to that known for fragile\nmolecular glass formers. A coupling model that accounts for the\n$t_{w}$-dependence of the stretching exponent is used to analyse and explain\nthe observed correlation between $t_{k}$ and $t^{\\infty}_{\\alpha}$."
    },
    {
        "anchor": "Mechanochemical subcellular-element model of crawling cells: Constructing physical models of living cells and tissues is an extremely\nchallenging task because of the high complexities of both intra- and\nintercellular processes. In addition, the force that a single cell generates\nvanishes in total due to the law of action and reaction. The typical mechanics\nof cell crawling involve periodic changes in the cell shape and in the adhesion\ncharacteristics of the cell to the substrate. However, the basic physical\nmechanisms by which a single cell coordinates these processes cooperatively to\nachieve autonomous migration are not yet well understood. To obtain a clearer\ngrasp of how the intracellular force is converted to directional motion, we\ndevelop a basic mechanochemical model of a crawling cell based on subcellular\nelements with the focus on the dependence of the protrusion and contraction as\nwell as the adhesion and deadhesion processes on intracellular biochemical\nsignals. By introducing reaction-diffusion equations that reproduce traveling\nwaves of local chemical concentrations, we clarify that the chemical dependence\nof the cell-substrate adhesion dynamics determines the crawling direction and\ndistance with one chemical wave. Finally, we also perform multipole analysis of\nthe traction force to compare it with the experimental results. To our\nknowledge, our present work is the first study that accomplishes fully\nforce-free migration utilizing intracellular chemical reactions. Although the\ndetailed mechanisms of actual cells are far more complicated than our simple\nmodel, we believe that this mechanochemical model is a good prototype for more\nrealistic models.",
        "positive": "Modeling size controlled nanoparticle precipitation with the co-solvency\n  method by spinodal decomposition: The co-solvency method is a method for the size controlled preparation of\nnanoparticles like polymersomes, where a poor co-solvent is mixed into a\nhomogeneous copolymer solution to trigger precipitation of the polymer. The\nsize of the resulting particles is determined by the rate of co-solvent\naddition. We use the Cahn-Hilliard equation with a Flory-Huggins free energy\nmodel to describe the precipitation of a polymer under changing solvent quality\nby applying a time dependent Flory-Huggins interaction parameter. The analysis\nfocuses on the characteristic size R of polymer aggregates that form during the\ninitial spinodal decomposition stage, and especially on how R depends on the\nrate s of solvent quality change. Both numerical results and a perturbation\nanalysis predict a power law dependence $R \\sim s^{-1/6}$, which is in\nagreement with power laws for the final particle sizes that have been reported\nfrom experiments and molecular dynamics simulations. Hence, our model results\nsuggest that the nanoparticle size in size-controlled precipitation is\nessentially determined during the spinodal decomposition stage."
    },
    {
        "anchor": "Surface Scaling Analysis of a Frustrated Spring-network Model for\n  Surfactant-templated Hydrogels: We propose and study a simplified model for the surface and bulk structures\nof crosslinked polymer gels, into which voids are introduced through templating\nby surfactant micelles. Such systems were recently studied by Atomic Force\nMicroscopy [M. Chakrapani et al., e-print cond-mat/0112255]. The gel is\nrepresented by a frustrated, triangular network of nodes connected by springs\nof random equilibrium lengths. The nodes represent crosslinkers, and the\nsprings correspond to polymer chains. The boundaries are fixed at the bottom,\nfree at the top, and periodic in the lateral direction. Voids are introduced by\ndeleting a proportion of the nodes and their associated springs. The model is\nnumerically relaxed to a representative local energy minimum, resulting in an\ninhomogeneous, ``clumpy'' bulk structure. The free top surface is defined at\nevenly spaced points in the lateral (x) direction by the height of the topmost\nspring, measured from the bottom layer, h(x). Its scaling properties are\nstudied by calculating the root-mean-square surface width and the generalized\nincrement correlation functions C_q(x)= <|h(x_0+x)-h(x_0)|^q>. The surface is\nfound to have a nontrivial scaling behavior on small length scales, with a\ncrossover to scale-independent behavior on large scales. As the vacancy\nconcentration approaches the site-percolation limit, both the crossover length\nand the saturation value of the surface width diverge in a manner that appears\nto be proportional to the bulk connectivity length. This suggests that a\npercolation transition in the bulk also drives a similar divergence observed in\nsurfactant templated polyacrylamide gels at high surfactant concentrations.",
        "positive": "Virial series for fluids of hard hyperspheres in odd dimensions: A recently derived method [R. D. Rohrmann and A. Santos, Phys. Rev. E. {\\bf\n76}, 051202 (2007)] to obtain the exact solution of the Percus-Yevick equation\nfor a fluid of hard spheres in (odd) $d$ dimensions is used to investigate the\nconvergence properties of the resulting virial series. This is done both for\nthe virial and compressibility routes, in which the virial coefficients $B_j$\nare expressed in terms of the solution of a set of $(d-1)/2$ coupled algebraic\nequations which become nonlinear for $d \\geq 5$. Results have been derived up\nto $d=13$. A confirmation of the alternating character of the series for $d\\geq\n5$, due to the existence of a branch point on the negative real axis, is found\nand the radius of convergence is explicitly determined for each dimension. The\nresulting scaled density per dimension $2 \\eta^{1/d}$, where $\\eta$ is the\npacking fraction, is wholly consistent with the limiting value of 1 for $d \\to\n\\infty$. Finally, the values for $B_j$ predicted by the virial and\ncompressibility routes in the Percus-Yevick approximation are compared with the\nknown exact values [N. Clisby and B. M. McCoy, J. Stat. Phys. {\\bf 122}, 15\n(2006)]"
    },
    {
        "anchor": "Topology Regulation during Replication of the Kinetoplast DNA: We study theoretically the replication of Kinetoplast DNA consisting of\nseveral thousands separate mini-circles found in organisms of the class\nKinetoplastida. When the cell is not actively dividing these are topologically\nconnected in a marginally linked network of rings with only one connected\ncomponent. During cell division each mini-circle is removed from the network,\nduplicated and then re-attached, along with its progeny. We study this process\nunder the hypothesis that there is a coupling between the topological state of\nthe mini-circles and the expression of genetic information encoded on them,\nleading to the production of Topoisomerase. This model describes a\nself-regulating system capable of full replication that reproduces several\nprevious experimental findings. We find that the fixed point of the system\ndepends on a primary free parameter of the model: the ratio between the rate of\nremoval of mini-circles from the network (R) and their (re)attachment rate (A).\nThe final topological state is found to be that of a marginally linked network\nstructure in which the fraction of mini-circles linked to the largest connected\ncomponent approaches unity as R/A decreases. Finally we discuss how this may\nsuggest an evolutionary trade-off between the speed of replication and the\naccuracy with which a fully topologically linked state is produced.",
        "positive": "Dynamics of water and ethanol in graphene oxide: We utilized the momentum transfer(Q)-dependence of Quasi-Elastic Neutron\nScattering (QENS) to reveal the dynamics of water and ethanol confined in\nGraphene Oxide (GO) powder or membranes at different temperatures and in\ndifferent orientations. The dynamics was measured across different length and\ntime scales using several spectrometers. We found reduced diffusivities (up to\n30\\% in the case of water) and a depression of the transition temperatures.\nWhile water showed near Arrhenius behavior with an almost bulk-like activation\nbarrier in a temperature range of 280-310 K, the diffusivity of ethanol showed\nlittle temperature dependence. For both water and ethanol, we found evidence\nfor immobile and mobile fractions of the confined liquid. The mobile fraction\nexhibited jump diffusion, with a jump length consistent with the expected\naverage spacing of hydroxide groups in the GO surfaces. From anisotropy\nmeasurements, we found weak anisotropy in diffusion, with the surprising result\nthat diffusion was faster perpendicular to membrane than parallel to it."
    },
    {
        "anchor": "Ionic phase transitions in non-ideal systems: We construct an explicitly solvable Landau mean-field theory for volume phase\ntransitions of confined or fixed ions driven by relative concentrations of\ndivalent and monovalent counterions. Such phase transitions have been widely\nstudied in ionic gels, where the mechanism relies on self-attraction or\nelasticity of a network. We find here that non-ideal behavior of ions in\naqueous solution can in theory drive phase transitions without a\nself-attracting or elastic network. We represent non-ideality by a\nDebye-H\\\"uckel-like power-law activity, or correlation free energy, and retain\na mechanical self-repulsion to avoid runaway collapse due to the non-ideal\nterm. Within this model we find a continuous line of gas-liquid-type critical\npoints, connecting a purely monovalent, divalent-sensitive critical point at\none extreme with a divalent, monovalent-sensitive critical point at the other.\nAn alternative representation of the Landau functional handles the second case.\nWe include a formula for electrical potential, which may be a convenient proxy\nfor critically varying volume. Our relatively simple mean-field formulation may\nfacilitate explorations of tunable critical sensitivity in areas such as ion\ndetection technology and biological osmotic control.",
        "positive": "Reorientation kinetics of superparamagnetic nanostructured rods: The attractive interactions between oppositely charged species (colloids,\nmacromolecules etc) dispersed in water are strong, and the direct mixing of\nsolutions containing such species generally yields to a precipitation, or to a\nphase separation. We have recently developed means to control the\nelectrostatically-driven attractions between nanoparticles and polymers in\nwater, and at the same time to preserve the stability of the dispersions. We\ngive here an account of the formation of supracolloidal aggregates obtained by\nco-assembly of 7 nm particles with copolymers. Nanostructured rods of length\ncomprised between 5 and 50 microns and diameter 500 nm were investigated. By\napplication of a magnetic field, the rods were found to reorient along with the\nmagnetic field lines. The kinetics of reorientation was investigated using step\nchanges of the magnetic field of amplitude 90 degrees. From the various results\nobtained, among which an exponential decay of the tangent of the angle made\nbetween the rod and the field, we concluded that the rods are\nsuperparamagnetic."
    },
    {
        "anchor": "Nematic Colloidal Swarms Assembled and Transported on Photosensitive\n  Surfaces: We demonstrate a novel method to assemble and transport swarms of colloidal\nparticles by combining liquid crystals enabled electrophoresis and\nphoto-sensitive surface patterning. Colloidal particles are propelled in a\nnematic liquid crystal via application of an alternating current electric\nfield. Swarms of particles are assembled into a rotating mill cluster, or moved\nas a whole along predefined paths photo-imprinted on chemically functionalized\nsubstrates. This technique represents an alternative approach to fluid based\nlab-on-a-chip technologies guiding the motion of large ensembles of micrometer\nscale solid or liquid inclusions.",
        "positive": "Dynamical solid-liquid transition through oscillatory shear: Starting from an ideal crystalline state, we numerically study a\nnonequilibrium dynamical order- disorder transition promoted by the application\nof a periodic shearing protocol at low temperatures in model systems in two and\nthree dimensions. We observe a continuous (2D) and discontinuous (3D) dynamical\ntransition from an ordered to a disordered steady state. Through the analysis\nof large-scale simulations, we show that the amorphization mechanism around the\ndiscontinuous transition is reminiscent of spinodal decomposition."
    },
    {
        "anchor": "Softening the \"crystal-scaffold\" for life's emergence: Del Giudice's group study how water can organize on hydrophilic surfaces\nforming coherent domains (loaning energy from the quantum vacuum), plus\nquasi-free electrons, whose excitations produce cold vortices, aligning to\nambient fields. Their electric and magnetic dipolar modes can couple to\noscillatory (electric-organic-dipoles), and/or rotary\n(magnetic-mineral-dipoles), besides responding to magnetic potentials. Thus,\nimprinted electromagnetic patterns of catalytic colloids - c.f. Cairns-Smith's\n\"crystal-scaffold\"- on their structured water partners could have equipped the\nlatter with a selection-basis for 'choosing' their context-based \"soft-matter\"\n(de Gennes) replacements. We consider the potential of the scenario of an\nexternal control on magnetic colloids forming in the Hadean hydrothermal\nsetting (of Russell and coworkers) - via a magnetic-rock-field - conceptually\nenabling self-assembly, induction of asymmetries, response effects towards\nclose-to-equilibrium dynamics, associative-networks, besides providing a\ncoherent environment for stabilizing associated symmetry-broken quanta, and\ntheir feedback-interactions with those of coherent water-domains, to address\nthe emergence of metabolism and replication.",
        "positive": "Phase diagram of the penetrable square well-model: We study a system formed by soft colloidal spheres attracting each other via\na square-well potential, using extensive Monte Carlo simulations of various\nnature. The softness is implemented through a reduction of the infinite part of\nthe repulsive potential to a finite one. For sufficiently low values of the\npenetrability parameter we find the system to be Ruelle stable with square-well\nlike behavior. For high values of the penetrability the system is\nthermodynamically unstable and collapses into an isolated blob formed by a few\nclusters each containing many overlapping particles. For intermediate values of\nthe penetrability the system has a rich phase diagram with a partial lack of\nthermodynamic consistency."
    },
    {
        "anchor": "Liquid crystal elastomer coatings with programmed response of surface\n  profile: Stimuli-responsive liquid crystal elastomers (LCEs) with a strong coupling of\norientational molecular order and rubber-like elasticity, show a great\npotential as working elements in soft robotics, sensing, transport and\npropulsion systems. We demonstrate a dynamic thermal control of the surface\ntopography of LCE coatings achieved through pre-designed patterns of in-plane\nmolecular orientation. These patterns determine whether the LCE coating\ndevelops elevations, depressions, or in-plane deformations. The deterministic\ndependence of the out-of-plane dynamic surface profile on the in-plane\norientational pattern is explained by activation forces. These forces are\ncaused by two factors: (i) stretching-contraction of the polymer networks\ndriven by temperature; (ii) spatially varying orientation of the LCE. The\nactivation force concept brings the responsive LCEs into the domain of active\nmatter. The demonstrated relationship can be used to design programmable\ncoatings with functionalities that mimic biological tissues such as skin.",
        "positive": "Conformational switching of chiral colloidal rafts regulates raft-raft\n  attractions and repulsions: Membrane-mediated particle interactions depend both on the properties of the\nparticles themselves and the membrane environment in which they are suspended.\nExperiments have shown that chiral rod-like inclusions dissolved in a colloidal\nmembrane of opposite handedness assemble into colloidal rafts, which are\nfinite-sized reconfigurable droplets consisting of a large but precisely\ndefined number of rods. Here, we systematically tune the chirality of the\nbackground membrane, and find that in the achiral limit colloidal rafts acquire\nfundamentally new structural properties and interactions. In particular, rafts\ncan switch between two chiral states of opposite handedness, which dramatically\nalters the nature of the membrane-mediated raft-raft interactions. Rafts with\nthe same chirality have long-ranged repulsions, while those with opposite\nchirality acquire attractions with a well-defined minimum. Both attractive and\nrepulsive interactions are explained by a continuum model that accounts for the\ncoupling between the membrane thickness and the local tilt of the constituent\nrods. These switchable interactions enable assembly of colloidal rafts into\nintricate higher-order architectures with unusual symmetries, including stable\ntetrameric clusters and \"ionic crystallites\" of counter-twisting domains\norganized on a binary square lattice. Furthermore, the properties of individual\nrafts, such as their sizes, are controlled by their complexation with other\nrafts. The emergence of these complex behaviors can be rationalized purely in\nterms of generic couplings between compositional and orientational order of\nfluids of rod-like elements. Thus, the uncovered principles might have\nrelevance for conventional lipid bilayers, in which the assembly of\nhigher-order structures is also mediated by complex membrane-mediated\ninteractions."
    },
    {
        "anchor": "Axially symmetric membranes with polar tethers: Axially symmetric equilibrium configurations of the conformally invariant\nWillmore energy are shown to satisfy an equation that is two orders lower in\nderivatives of the embedding functions than the equilibrium shape equation, not\none as would be expected on the basis of axial symmetry. Modulo a translation\nalong the axis, this equation involves a single free parameter c.If c\\ne 0, a\ngeometry with spherical topology will possess curvature singularities at its\npoles. The physical origin of the singularity is identified by examining the\nNoether charge associated with the translational invariance of the energy; it\nis consistent with an external axial force acting at the poles. A one-parameter\nfamily of exact solutions displaying a discocyte to stomatocyte transition is\ndescribed.",
        "positive": "Aging or DEAD: origin of the non-monotonic response to weak\n  self-propulsion in active glasses: Among amorphous states, glass is defined by relaxation times longer than the\nobservation time. This nonergodic nature makes the understanding of glassy\nsystems an involved topic, with complex aging effects or responses to further\nout-of-equilibrium external drivings. In this respect active glasses made of\nself-propelled particles have recently emerged as stimulating systems which\nbroadens and challenges our current understanding of glasses by considering\nnovel internal out-of-equilibrium degrees of freedom. In previous experimental\nstudies we have shown that in the ergodicity broken phase, the dynamics of\ndense passive particles first slows down as particles are made slightly active,\nbefore speeding up at larger activity. Here, we show that this nonmonotonic\nbehavior also emerges in simulations of soft active Brownian particles and\nexplore its cause. We refute that the Deadlock by Emergence of Active\nDirectionality (DEAD) model we proposed earlier describes our data. However, we\ndemonstrate that the nonmonotonic response is due to activity enhanced aging,\nand thus confirm the link with ergodicity breaking. Beyond self-propelled\nsystems, our results suggest that aging in active glasses is not fully\nunderstood."
    },
    {
        "anchor": "Slip of fluid molecules on solid surfaces by surface diffusion: The mechanism of fluid slip on a solid surface has been linked to surface\ndiffusion, by which mobile adsorbed fluid molecules perform hops between\nadsorption sites. However, slip velocity arising from this surface hopping\nmechanism has been estimated to be significantly lower than that observed\nexperimentally. In this paper, we propose a re-adsorption mechanism for fluid\nslip. Slip velocity predictions via this mechanism show the improved agreement\nwith experimental measurements.",
        "positive": "Importance of Metastable States in the Free Energy Landscapes of\n  Polypeptide Chains: We show that the interplay between excluded volume effects, hydrophobicity,\nand hydrogen bonding of a tube-like representation of a polypeptide chain gives\nrise to free energy landscapes that exhibit a small number of metastable minima\ncorresponding to common structural motifs observed in proteins. The complexity\nof the landscape increases only moderately with the length of the chain.\nAnalysis of the temperature dependence of these landscapes reveals that the\nstability of specific metastable states is maximal at a temperature close to\nthe mid-point of folding. These mestastable states are therefore likely to be\nof particular significance in determining the generic tendency of proteins to\naggregate into potentially pathogenic agents."
    },
    {
        "anchor": "Small ionic radii limit time step in Martini 3 molecular dynamics\n  simulations: Among other improvements, the Martini 3 coarse-grained force field provides a\nmore accurate description of the solvation of protein pockets and channels\nthrough the consistent use of various bead types and sizes. Here, we show that\nthe representation of Na$^+$ and Cl$^-$ ions as \"tiny\" (TQ5) beads limits the\naccessible time step to 25 fs. By contrast, with Martini 2, time steps of 30-40\nfs were possible for lipid bilayer systems without proteins. This limitation is\nrelevant for, e.g., phase separating lipid mixtures that require long\nequilibration times. We derive a quantitative kinetic model of time-integration\ninstabilities in molecular dynamics (MD) as a function of time step, ion\nconcentration and mass, system size, and simulation time. With this model, we\ndemonstrate that ion-water interactions are the main source of instability at\nphysiological conditions, followed closely by ion-ion interactions. We show\nthat increasing the ionic masses makes it possible to use time steps up to 40\nfs with minimal impact on static equilibrium properties and on dynamical\nquantities such as lipid and ion diffusion coefficients. Increasing the size of\nthe bead representing the ions (and thus changing their hydration) also permits\nlonger time steps. The use of larger time steps in Martini 3 simulations\nresults in a more efficient exploration of configuration space. The kinetic\nmodel of MD simulation crashes can be used to determine the maximum allowed\ntime step whenever sampling efficiency is critical.",
        "positive": "Island Hopping of active colloids: Individual self-propelled colloidal particles, like active Brownian particles\n(ABP) or run-and-tumble swimmers (RT), exhibit characteristic and well-known\nmotion patterns. However, their interaction with obstacles remains an open and\nimportant problem. We here investigate the two-dimensional motion of\nsilica-gold Janus particles (JP) actuated by AC electric fields and suspended\nand cruising through silica particles organized in rafts by mutual phoretic\nattraction. A typical island contains dozens of particles. The JP travels\nstraight in obstacle-free regions and reorients systematically upon approaching\nan island. As an underlying mechanism, we tentatively propose a hydrodynamic\ntorque exerted by the solvent flow towards the islands on the JP local flow\nfield, leading to an alignment of respective solvent flow directions. This\nsystematic behavior is in contrast with the reorientation observed for free\nactive Brownian particles and run-and-tumble microswimmers."
    },
    {
        "anchor": "Unconventional Localization Prior to Wrinkles and Controllable Surface\n  Patterns of Film Substrate Bilayers Through Patterned Defects in Substrate: A novel bilayer is introduced, consisting of a stiff film adhered to a soft\nsubstrate with patterned holes beneath the film and substrate interface. To\nuncover the transition of surface patterns, two dimensional plane strain\nsimulations are performed on the defected bilayer subjected to uniaxial\ncompression. Although the substrate is considered as the linear elastic\nmaterial, the presence of defects can directly trigger the formation of locally\nridged and then folding configurations from flat surface with a relatively\nsmall compressive strain. It is followed by the coexisting phases of folds and\nwrinkles under further overall compression. This phase transition reverses the\ntraditional transition of wrinkle to ridge or fold for defect free substrates.\nIt is also found that the onset of initial bifurcation is highly dependent on\nthe spatial configuration and geometries of holes, since the interaction of\ndefects allows more strain relief mechanisms beyond wrinkling. Furthermore, a\nrich diversity of periodic surface topologies, including overall waves,\nlocalizations, saw like and coexisting features of folds and wrinkles can be\nobtained by varying the diameter, depth and spacing of holes as well as\ncompressive strain, which provides a potential approach to engineer various\nsurface patterns for applications.",
        "positive": "Electrostatic image effects for counter-ions between charged planar\n  walls: We study the effect of dielectric inhomogeneities on the interaction between\ntwo planparallel charged surfaces with oppositely charged mobile charges in\nbetween. The dielectric constant between the surfaces is assumed to be\ndifferent from the dielectric constant of the two semiinfinite regions bounded\nby the surfaces, giving rise to electrostatic image interactions. We show that\non the weak coupling level the image charge effects are generally small, making\ntheir mark only in the second order fluctuation term. However, in the strong\ncoupling limit, the image effects are large and fundamental. They modify the\ninteractions between the two surfaces in an essential way. Our calculations are\nparticularly useful in the regime of parameters where computer simulations\nwould be difficult and extremely time consuming due to the complicated nature\nof the long range image potentials."
    },
    {
        "anchor": "Strong-coupling expansions for the topologically inhomogeneous\n  Bose-Hubbard model: We consider a Bose-Hubbard model with an arbitrary hopping term and provide\nthe boundary of the insulating phase thereof in terms of third-order strong\ncoupling perturbative expansions for the ground state energy. In the general\ncase two previously unreported terms occur, arising from triangular loops and\nhopping inhomogeneities, respectively. Quite interestingly the latter involves\nthe entire spectrum of the hopping matrix rather than its maximal eigenpair,\nlike the remaining perturbative terms. We also show that hopping\ninhomogeneities produce a first order correction in the local density of\nbosons. Our results apply to ultracold bosons trapped in confining potentials\nwith arbitrary topology, including the realistic case of optical superlattices\nwith uneven hopping amplitudes. Significant examples are provided. Furthermore,\nour results can be extented to magnetically tuned transitions in Josephson\njunction arrays.",
        "positive": "Two-Time Correlations for Probing the Aging Dynamics of Jammed Colloids: We present results for the aging dynamics of a jammed 2D colloidal system\nobtained with molecular dynamics simulations. We performed extensive\nsimulations to gather detailed statistics about rare rearrangement events. With\na simple criterion for identifying irreversible events based on Voronoi\ntessellations, we find that the rate of those events decelerates\nhyperbolically. We track the probability density function for particle\ndisplacements, the van-Hove function, with sufficient statistics as to reveal\nits two-time dependence that is indicative of aging. Those displacements,\nmeasured from a waiting time $t_{w}$ after the quench up to times\n$t=t_{w}+\\Delta t$, exhibit a data collapse as a function of $\\Delta t/t_{w}$.\nThese findings can be explained comprehensively as manifestations of \"record\ndynamics\", i.e., a relaxation dynamic driven by record-breaking fluctuations.\nWe show that an on-lattice model of a colloid that was built on record dynamics\nindeed reproduces the experimental results in great detail."
    },
    {
        "anchor": "Crossover in the Slow Decay of Dynamic Correlations in the Lorentz Model: The long-time behavior of transport coefficients in a model for spatially\nheterogeneous media in two and three dimensions is investigated by Molecular\nDynamics simulations. The behavior of the velocity auto-correlation function is\nrationalized in terms of a competition of the critical relaxation due to the\nunderlying percolation transition and the hydrodynamic power-law anomalies. In\ntwo dimensions and in the absence of a diffusive mode, another power law\nanomaly due to trapping is found with an exponent -3 instead of -2. Further,\nthe logarithmic divergence of the Burnett coefficient is corroborated in the\ndilute limit; at finite density, however, it is dominated by stronger\ndivergences.",
        "positive": "Binary Mixtures of Locally Coupled Mobile Oscillators: We study synchronization dynamics in binary mixtures of locally coupled\nKuramoto oscillators which perform Brownian motion in a two-dimensional box. We\nintroduce two models, where in model $\\cal I$ there are two type of\noscillators, say $\\cal A$ and $\\cal B$, and any two similar oscillators tend to\nsynchronize their phases, while any two dissimilar ones tend to be out of\nphase. In model $\\cal J$, in contrast, the oscillators in subpopulation $\\cal\nA$ behave as in model $\\cal I$, while the oscillators in subpopulation $\\cal B$\ntend to be out of phase with all the others. In the real space all the\noscillators in both models interact via a soft-core repulsive potential. Both\nsubpopulations of model $\\cal I$ and subpopulation $\\cal A$ of model $\\cal J$,\nby their own, exhibit a phase coherent attractor in a certain region of model\nparameters. The approach to the attractor, after an initial transient regime,\nis exponential with some characteristic synchronization time scale $\\tau$.\nNumerical analysis reveals that the attractors of the two subpopulations\nsurvive within model $\\cal I$, regardless of the composition of the mixture\n$\\phi$ and the strength of the cross-population negative coupling constant $H$,\nand that $\\tau$ sensitively depends on $\\phi$, $H$ and the packing fraction. In\nparticular, the ability of the oscillators to move and exchange neighbours can\nsignificantly decrease $\\tau$. In contrast, model $\\cal J$ predicts suppression\nof the synchronized state in subpopulation $\\cal A$ and emergence of the\ncoherent attractor in the \"contrarians\" subpopulation $\\cal B$ for strong and\nweak cross-population coupling, respectively."
    },
    {
        "anchor": "Heterogeneous interactions and polymer entropy decide organization and\n  dynamics of chromatin domains: Chromatin is known to be organized into multiple domains of varying sizes and\ncompaction. While these domains are often imagined as static structures, they\nare highly dynamic and show cell-to-cell variability. Since processes such as\ngene regulation and DNA replication occur in the context of these domains, it\nis important to understand their organization, fluctuation and dynamics. To\nsimulate chromatin domains, one requires knowledge of interaction strengths\namong chromatin segments. Here, we derive interaction strength parameters from\nexperimentally known contact maps and use them to predict chromatin\norganization and dynamics. Taking two domains on the human chromosome as\nexamples, we investigate its 3D organization, size/shape fluctuations, and\ndynamics of different segments within a domain, accounting for hydrodynamic\neffects. Considering different cell types, we quantify changes in interaction\nstrengths and chromatin shape fluctuations in different epigenetic states.\nPerturbing the interaction strengths systematically, we further investigate how\nepigenetic-like changes can alter the spatio-temporal nature of the domains.\nOur results show that heterogeneous weak interactions are crucial in\ndetermining the organization of the domains. Computing effective stiffness and\nrelaxation times, we investigate how perturbations in interactions affect the\nsolid-like and liquid-like nature of chromatin domains. Quantifying dynamics of\nchromatin segments within a domain, we show how the competition between polymer\nentropy and interaction energy influence the timescales of loop formation and\nmaintenance of stable loops.",
        "positive": "Electrically powered locomotion of dual-nature colloid-hedgehog and\n  colloid-umbilic topological and elastic dipoles in liquid crystals: Colloidal particles in liquid crystals tend to induce topological defects and\ndistortions of the molecular alignment within the surrounding anisotropic host\nmedium, which results in elasticity-mediated interactions not accessible to\ntheir counterparts within isotropic fluid hosts. Such particle-induced coronae\nof perturbed nematic order are highly responsive to external electric fields,\neven when the uniformly aligned host medium away from particles exhibits no\nresponse to fields below the realignment threshold. Here we harness the\nnon-reciprocal nature of these facile electric responses to demonstrate\ncolloidal locomotion. Oscillations of electric field prompt repetitive\ndeformations of the corona of dipolar elastic distortions around the colloidal\ninclusions, which at appropriately designed electric driving synchronize the\ndisplacement directions. We observe the colloid-hedgehog dipole accompanied by\nan umbilical defect in the tilt directionality field (c-field), along with the\ntexture of elastic distortions that evolves with changing applied voltage. The\ntemporal out-of-equilibrium evolution of the director and c-field distortions\naround particles upon turning voltage on and off is not invariant upon reversal\nof time, prompting lateral translations and interactions that markedly differ\nfrom what is accessible to these colloids under equilibrium conditions. Our\nfindings may lead to both technological and fundamental science applications of\nnematic colloids as both model reconfigurable colloidal systems and as\nmesostructured materials with pre-designed temporal evolution of structure and\ncomposition."
    },
    {
        "anchor": "Shear-induced crystallization of a dense rapid granular flow:\n  hydrodynamics beyond the melting point?: We investigate shear-induced crystallization in a very dense flow of\nmono-disperse inelastic hard spheres. We consider a steady plane Couette flow\nunder constant pressure and neglect gravity. We assume that the granular\ndensity is greater than the melting point of the equilibrium phase diagram of\nelastic hard spheres. We employ a Navier-Stokes hydrodynamics with constitutive\nrelations all of which (except the shear viscosity) diverge at the crystal\npacking density, while the shear viscosity diverges at a smaller density. The\nphase diagram of the steady flow is described by three parameters: an effective\nMach number, a scaled energy loss parameter, and an integer number m: the\nnumber of half-oscillations in a mechanical analogy that appears in this\nproblem. In a steady shear flow the viscous heating is balanced by energy\ndissipation via inelastic collisions. This balance can have different forms,\nproducing either a uniform shear flow or a variety of more complicated,\nnonlinear density, velocity and temperature profiles. In particular, the model\npredicts a variety of multi-layer two-phase steady shear flows with sharp\ninterphase boundaries. Such a flow may include a few zero-shear (solid-like)\nlayers, each of which moving as a whole, separated by fluid-like regions. As we\nare dealing with a hard sphere model, the granulate is fluidized within the\n\"solid\" layers: the granular temperature is non-zero there, and there is energy\nflow through the boundaries of the \"solid\" layers. A linear stability analysis\nof the uniform steady shear flow is performed, and a plausible bifurcation\ndiagram of the system, for a fixed m, is suggested. The problem of selection of\nm remains open.",
        "positive": "Accumulating Particles at the Boundaries of a Laminar Flow: The accumulation of small particles is analyzed in stationary flows through\nchannels of variable width at small Reynolds number. The combined influence of\npressure, viscous drag and thermal fluctuations is described by means of a\nFokker-Planck equation for the particle density. It is shown that in the limit\nof vanishing particle size a uniform particle distribution is always approached\nin the long time limit. For extended spherical particles, conditions are\nspecified that lead to inhomogeneous densities and consequently to particle\naccumulation and depletion. Hereby the boundary conditions for the particle\ndensity play a decisive role: The centers of spherical particles must keep the\nminimal distance of their radius from the fluid boundaries. The normal\ncomponents of the forces acting on the sphere then may assume finite values\nwhich are diffusively transported into the bulk of the fluid."
    },
    {
        "anchor": "A finite element approach to self-consistent field theory calculations\n  of multiblock polymers: Self-consistent field theory (SCFT) has proven to be a powerful tool for\nmodeling equilibrium microstructures of soft materials, particularly for\nmultiblock polymers. A very successful approach to numerically solving the SCFT\nset of equations is based on using a spectral approach. While widely\nsuccessful, this approach has limitations especially in the context of current\ntechnologically relevant applications. These limitations include non-trivial\napproaches for modeling complex geometries, difficulties in extending to\nnon-periodic domains, as well as non-trivial extensions for spatial adaptivity.\nAs a viable alternative to spectral schemes, we develop a finite element\nformulation of the SCFT paradigm for calculating equilibrium polymer\nmorphologies. We discuss the formulation and address implementation challenges\nthat ensure accuracy and efficiency. We explore higher order chain contour\nsteppers that are efficiently implemented with Richardson Extrapolation. This\napproach is highly scalable and suitable for systems with arbitrary shapes. We\nshow spatial and temporal convergence and illustrate scaling on up to 2048\ncores. Finally, we illustrate confinement effects for selected complex\ngeometries. This has implications for materials design for nanoscale\napplications where dimensions are such that equilibrium morphologies\ndramatically differ from the bulk phases.",
        "positive": "Coarsening modes of clusters of aggregating particles: There are two modes by which clusters of aggregating particles can coalesce:\nThe clusters can merge either (i) by the Ostwald ripening process in which\nparticles diffuse from one cluster to the other whilst the cluster centres\nremain stationary, or (ii) by means of a cluster translation mode, in which the\nclusters move towards each other and join. To understand in detail the\ninterplay between these different modes, we study a model system of hard\nparticles with an additional attraction between them. The particles diffuse\nalong narrow channels with smooth or periodically corrugated walls, so that the\nsystem may be treated as one-dimensional. When the attraction between the\nparticles is strong enough, they aggregate to form clusters. The channel\npotential influences whether clusters can move easily or not through the system\nand can prevent cluster motion. We use Dynamical Density Functional theory to\nstudy the dynamics of the aggregation process, focusing in particular on the\ncoalescence of two equal size clusters. As long as the particle hard-core\ndiameter is non-zero, we find that the coalescence process can be halted by a\nsufficiently strong corrugation potential. The period of the potential\ndetermines the size of the final stable clusters. For the case of smooth\nchannel walls, we demonstrate that there is a cross-over in the dominance of\nthe two different coarsening modes, that depends on the strength of the\nattraction between particles, the cluster sizes and the separation distance\nbetween clusters."
    },
    {
        "anchor": "Anisotropic Capillary Interactions and Jamming of Colloidal Particles\n  Trapped at a Liquid-Fluid Interface: We determine the capillary attraction and equilibrium configurations of\nparticles trapped at a liquid-fluid interface due to the pinning of their\ncontact-line. We calculate analytically the asymptotic interaction energy\nbetween two particles and, numerically, the multi-body energy landscape for up\nto four contacting particles. Our results are consistent with recent\nexperiments. We show that a system composed of a large number of such particles\nbehaves as a jammed system.",
        "positive": "Anisotropic de Gennes narrowing in confined fluids: The collective diffusion of dense fluids in spatial confinement was studied\nby combining high-energy (21 keV) x-ray photon correlation spectroscopy and\nsmall-angle x-ray scattering from colloid-filled microfluidic channels. We\nfound the structural relaxation in confinement to be slower compared to bulk.\nThe collective dynamics is wave vector dependent, akin to de Gennes narrowing\ntypically observed in bulk fluids. However, in stark contrast to bulk, the\nstructure factor and de Gennes narrowing in confinement are anisotropic. These\nexperimental observations are essential in order to develop a microscopic\ntheoretical description of collective diffusion of dense fluids in confined\ngeometries."
    },
    {
        "anchor": "Floppy hydrated salt microcrystals: The crystalline structure of minerals due to the highly ordered assembly of\nits constituent atoms, ions or molecules confers a considerable hardness and\nbrittleness to the materials. As a result, they are generally subject to\nfracture. Here we report that microcrystals of natural inorganic salt hydrates\nsuch as sodium sulfate decahydrate (Na2SO4.10H2O) and magnesium sulfate\nhexahydrate (MgSO4.6H2O) can behave remarkably differently: instead of having a\ndefined faceted geometrical shape and being hard or brittle, they lose their\nfacets and become soft and deformable when in contact with their saturated salt\nsolution at their deliquescence point. As a result, the hydrated crystals\nsimultaneously behaves as crystalline and liquid-like. We show that the\nobserved elasticity is a consequence of a trade-off between the excess\ncapillary energy introduced by the deformation from the equilibrium shape and\nviscous flow over the surface of the microcrystals. This surprising, unusual\nmechanical properties reported here reveals the role of the water molecules\npresent in the crystalline structure. Although many compounds can incorporate\nwater molecules in their crystalline frameworks, the relationship between the\ndifferent hydrates and anhydrate crystal forms are still poorly investigated.\nOur results on the floppy behaviour of such crystalline structure reveals some\nunexplored properties of water molecules entrapped in the crystalline structure\nand can open novel routes for their application in various fields such as\npharmaceutical sciences, thermal energy storage and even the traceability of\nwater on Mars.",
        "positive": "Simulation of pattern dynamics of cohesive granular particles under a\n  plane shear: We have performed three-dimensional molecular dynamics simulation of cohesive\ngranular particles under a plane shear. From the simulation, we found the\nexistence of three distinct phases in steady states: (I) a uniform shear phase,\n(II) a coexistent phase of a shear band and a gas region and (III) a crystal\nphase. We also found that the critical line between (II) and (III) is\napproximately represented by $\\zeta \\propto \\exp(\\beta \\dot\\gamma L_y)$, where\n$\\zeta$, $\\beta$, $\\dot\\gamma$, $L_y$ are the dissipation rate, an unimportant\nconstant, the shear rate and the system size of the velocity gradient\ndirection, respectively."
    },
    {
        "anchor": "Intermittent rearrangements accompanying thermal fluctuations\n  distinguish glasses from crystals: It is a persistent problem in condensed matter physics that glasses exhibit\nvibrational and thermal properties that are markedly different from those of\ncrystals. While recent works have advanced our understanding of vibrational\nexcitations in glasses at the harmonic approximation limit, efforts in\nunderstanding finite-temperature anharmonic processes have been limited. It is\nwell known that phonons in crystals couple through phonon-phonon interactions,\nan extremely efficient mechanism for anharmonic decay that is also important in\nglasses. Here, however, we show that an additional anharmonic channel of\ndifferent origin emerges in the case of glasses, which induces intermittent\nrearrangements of particles. We have found that thermal vibrations in glasses\ntrigger transitions among numerous different local minima of the energy\nlandscape, which, however, are located within the same wide (meta)basin. These\nprocesses generate motions that are different from both diffusive and\nout-of-equilibrium aging dynamics. We suggest that the intermittent\nrearrangements accompanying thermal fluctuations are crucial features\ndistinguishing glasses from crystals.",
        "positive": "Concurrent factors determine toughening in the hydraulic fracture of\n  poroelastic composites: Brittle materials fail catastrophically. In consequence of their limited\nflaw-tolerance, failure occurs by localized fracture and is typically a dynamic\nprocess. Recently, experiments on epithelial cell monolayers have revealed that\nthis scenario can be significantly modified when the material susceptible to\ncracking is adhered to a hydrogel substrate. Thanks to the hydraulic coupling\nbetween the brittle layer and the poroelastic substrate, such a composite can\ndevelop a toughening mechanism that relies on the simultaneous growth of\nmultiple cracks. Here, we study this remarkable behaviour by means of a\ndetailed model, and explore how the material and loading parameters concur in\ndetermining the macroscopic toughness of the system. By extending a previous\nstudy, our results show that rapid loading conveys material toughness by\npromoting distributed cracking. Moreover, our theoretical findings may suggest\ninnovative architectures of flaw-insensitive materials with higher toughness."
    },
    {
        "anchor": "Multiscale Surface-Attached Hydrogel Thin Films with Tailored\n  Architecture: A facile route for the fabrication of surface-attached hydrogel thin films\nwith well-controlled chemistry and tailored architecture on wide range of\nthickness from nanometers to micrometers is reported. The synthesis, which\nconsists in cross-linking and grafting the preformed and ene-reactive polymer\nchains through thiol--ene click chemistry, has the main advantage of being\nwell-controlled without the addition of initiators. As thiol--ene click\nreaction can be selectively activated by UV-irradiation (in addition to thermal\nheating), micropatterned hydrogel films are easily synthesized. The versatility\nof our approach is illustrated by the possibility to fabricate various chemical\npolymer networks, like stimuli-responsive hydrogels, on various solid\nsubstrates, such as silicon wafers, glass, and gold surfaces. Another\nattractive feature is the development of new complex hydrogel films with\ntargeted architecture. The fabrication of various architectures for polymer\nfilms is demonstrated: multilayer hydrogel films in which single-networks are\nstacked one onto the other, interpenetrating networks films with mixture of two\nnetworks in the same layer, and nanocomposite hydrogel films where\nnanoparticles are stably trapped inside the mesh of the network. Thanks to its\nsimplicity and its versatility this novel approach to surface-attached hydrogel\nfilms should have a strong impact in the area of polymer coatings",
        "positive": "Structural instability of vortices in Bose-Einstein condensates: In this paper we study a gaseous Bose-Einstein condensate (BEC) and show\nthat: (i) A minimum value of the interaction is needed for the existence of\nstable persistent currents. (ii) Vorticity is not a fundamental invariant of\nthe system, as there exists a conservative mechanism which can destroy a vortex\nand change its sign. (iii) This mechanism is suppressed by strong interactions."
    },
    {
        "anchor": "Amorphization of a crystalline solid by plastic deformation: We demonstrate that plastic deformation in solids is associated with a\ndynamic transition that is reminiscent to the transition from a superconducting\nto a mixed phase in Type II superconductors. We report analytic calculations,\nextensive molecular dynamics and sequential umbrella sampling Monte Carlo\nsimulations of a two dimensional triangular crystalline solid undergoing\nplastic deformation under strain. The solid consists of particles connected by\nharmonic springs. Non-affine displacement fluctuations of the solid are\nenhanced using an external field, causing a rich deformation behaviour. The\nexternal field leads to a mixed phase, where defect and stress-free\ncrystallites are surrounded by a network of amorphous regions with large local\ninternal stress --- a \"stress Meissner\" effect. The transition shows slow\nageing dynamics caused by the presence of many competing, non-crystalline\nfree-energy minima. Under uniform uniaxial strain, this amorphization\ntransition gives rise to irreversible plastic deformation with the amorphous\nregions appearing as band-like structures. Our results may be checked by\ncareful experiments on colloidal crystals using holographic optical tweezers.",
        "positive": "Selective adsorption of ions in charged slit-systems: We study the selective adsorption of various cations into a layered slit\nsystem using grand canonical Monte Carlo simulations. The slit system is formed\nby a series of negatively charged membranes. The electrolyte contains two kinds\nof cations with different sizes and valences modelled by charged hard spheres\nimmersed in a continuum dielectric solvent. We present the results for various\ncases depending on the combinations of the properties of the competing cations.\nWe concentrate on the case when the divalent cations are larger than the\nmonovalent cations. In this case, size and charge have counterbalancing\neffects, which results in interesting selectivity phenomena."
    },
    {
        "anchor": "Glass transition temperature of thin polymer films: The glass transition temperature and its connection to statistical properties\nof confined and free-standing polymer films of varying thickness containing\nunentangled to highly entangled bead-spring chains are studied by molecular\ndynamics simulations. For confined films, perfect scaling of the\nthickness-dependent end-to-end distance and radius of gyrations normalized to\ntheir bulk values in the directions parallel and perpendicular to the surfaces\nis obtained. Particularly, the reduced end-to-end distance in the perpendicular\ndirection is very well described by the extended Silberberg model. For bulk\npolymer melts, the relation between chain length and $T_g$ follows the\nFox-Flory equation while $T_g$ for a given film thickness is almost independent\nof chain length. For films, $T_g$ decreases and is well described by Keddie's\nformula, where the reduction is more pronounced for free-standing films. For\nthe present model, $T_g$ begins to deviate from bulk $T_g$ at the\ncharacteristic film thickness, where the average bond orientation becomes\nanisotropic and the entanglement density decreases.",
        "positive": "A Geometric Criterion for the Optimal Spreading of Active Polymers in\n  Porous Media: We perform Brownian dynamics simulations of active stiff polymers undergoing\nrun-reverse dynamics, and so mimic bacterial swimming, in porous media. In\naccord with recent experiments of \\emph{Escherichia coli}, the polymer dynamics\nare characterized by trapping phases interrupted by directed hopping motion\nthrough the pores. We find that the effective translational diffusivities of\nrun-reverse agents can be enhanced up to two orders in magnitude, compared to\ntheir non-reversing counterparts, and exhibit a non-monotonic behavior as a\nfunction of the reversal rate, which we rationalize using a coarse-grained\nmodel. Furthermore, we discover a geometric criterion for the optimal\nspreading, which emerges when their run lengths are comparable to the longest\nstraight path available in the porous medium. More significantly, our criterion\nunifies results for porous media with disparate pore sizes and shapes and thus\nprovides a fundamental principle for optimal transport of microorganisms and\ncargo-carriers in densely-packed biological and environmental settings."
    },
    {
        "anchor": "Spontaneous Symmetry Breaking in Polar Fluids: Spontaneous symmetry breaking and emergent polar order are each of\nfundamental importance to a range of scientific disciplines, as well as\ngenerating rich phase behaviour in liquid crystals (LCs). Here, we show the\nunion of these phenomena to lead to two previously undiscovered polar liquid\nstates of matter. Both phases have a lamellar structure with an inherent polar\nordering of their constituent molecules. The first of these phases is\ncharacterised by polar order and a local tilted structure; the tilt direction\nprecesses about a helix orthogonal to the layer normal, the period of which is\nsuch that we observe selective reflection of light. The second new phase type\nis anti-ferroelectric, with the constituent molecules aligning orthogonally to\nthe layer normal. This has led us to term the phases the SmC_P^H and SmAAF\nphases, respectively. Further to this, we obtain room temperature ferroelectric\nnematic (NF) and SmC_P^Hphases via binary mixture formulation of the novel\nmaterials described here with a standard NF compound (DIO), with the resultant\nmaterials having melting points (and/or glass transitions) which are\nsignificantly below ambient temperature.",
        "positive": "Mesoscale phenomena in solutions of 3-methylpyridine, heavy water, and\n  an antagonistic salt: We have investigated controversial issues regarding the mesoscale behavior of\n3-methylpyridine (3MP), heavy water, and sodium tetraphenylborate (NaBPh4)\nsolutions by combining results obtained from dynamic light scattering (DLS) and\nsmall-angle neutron scattering (SANS). We have addressed three questions: (i)\nwhat is the origin of the mesoscale inhomogeneities (order of 100 nm in size)\nmanifested by the \"slow mode\" in DLS? (ii) Is the periodic structure observed\nfrom SANS an inherent property of this system? (iii) What is the universality\nclass of critical behavior in this system? Our results confirm that the \"slow\nmode\" observed from DLS experiments corresponds to long-lived, highly stable\nmesoscale droplets (order of 100 nm in size), which occur only when the solute\n(3MP) is contaminated by hydrophobic impurities. SANS data confirm the presence\nof a periodic structure with a periodicity of about 10 nm. This periodic\nstructure cannot be eliminated by nanopore filtration and thus is indeed an\ninherent solution property. The critical behavior of this system, in the range\nof concentration and temperatures investigated by DLS experiments, indicates\nthat the criticality belongs to the universality class of the 3-dimensional\nIsing model."
    },
    {
        "anchor": "Shear flow of dense granular materials near smooth walls. I. Shear\n  localization and constitutive laws in boundary region: We report on a numerical study of the shear flow of a simple two-dimensional\nmodel of a granular material under controlled normal stress between two\nparallel smooth, frictional walls, moving with opposite velocities $\\pm$V .\nDiscrete simulations, which are carried out with the contact dynamics method in\ndense assemblies of disks, reveal that, unlike rough walls made of strands of\nparticles, smooth ones can lead to shear strain localization in the boundary\nlayer. Specifically, we observe, for decreasing V, first a fluid-like regime\n(A), in which the whole granular layer is sheared, with a homogeneous strain\nrate except near the walls; then (B) a symmetric velocity profile with a solid\nblock in the middle and strain localized near the walls and finally (C) a state\nwith broken symmetry in which the shear rate is confined to one boundary layer,\nwhile the bulk of the material moves together with the opposite wall. Both\ntransitions are independent of system size and occur for specific values of V .\nTransient times are discussed. We show that the first transition, between\nregimes A and B, can be deduced from constitutive laws identified for the bulk\nmaterial and the boundary layer, while the second one could be associated with\nan instability in the behavior of the boundary layer. The boundary zone\nconstitutive law, however, is observed to depend on the state of the bulk\nmaterial nearby.",
        "positive": "Fluid membranes can drive linear aggregation of adsorbed spherical\n  nanoparticles: Using computer simulations we show that lipid membranes can mediate linear\naggregation of spherical nanoparticles binding to it for a wide range of\nbiologically relevant bending rigidities. This result is in net contrast with\nthe isotropic aggregation of nanoparticles on fluid interfaces or the expected\nclustering of isotropic insertions in biological membranes. We present a phase\ndiagram indicating where linear aggregation is expected, and compute explicitly\nthe free energy barriers associated with linear and isotropic aggregation.\nFinally, we provide simple scaling arguments to explain this phenomenology."
    },
    {
        "anchor": "Origin of magnetic moments and ferromagnetic properties of potassium\n  clusters in zeolite A: K clusters arrayed in zeolite A are investigated in detail. K clusters are\ngenerated in regular alpha-cages of zeolite A by the loading of guest K metal\nat a loading density of K atoms per alpha-cage, $n$. The value of $n$ was\nchanged from 0 to 7.2. It is known that this system shows ferromagnetic\nproperties for $n > 2$, where the Curie temperature increases with $n$, has a\npeak of approx,8 K at $n approx 3.6$, and decreases to 0 K at $n = 7.2$. The\nnegative Weiss temperature is estimated from the Curie-Weiss law for $n > 2$. A\nspherical quantum-well (SQW) model for the K cluster with 1$s$, 1$p$, and 1$d$\nquantum states has previously been proposed, and the ferromagnetic properties\nwere explained as being due to $s$-electrons in 1$p$ states. A spin-cant model\nof Mott-insulator antiferromagnetism in a K cluster array has been proposed for\nthe origin of the ferromagnetic properties. However, the SQW model cannot\nexplain either the $n$-dependence of the Curie temperature or that of the Curie\nconstant. In the present study, detailed measurements were made of the optical\nreflection, magnetic properties, electron spin resonance, and electrical\nresistivities. An optical reflection band at 0.7 eV is clearly observed for $2\n< n < 6$ at low temperatures, and is assigned to the excitation of the\nsigma-bonding state between 1$p$-states in adjoining alpha-cages. The\nelectrical resistivity indicates an insulating state continuously for $n$. We\npropose an advanced SQW model with consideration for sigma-bonding, the orbital\northogonality of 1$p$-hole states, and also the superlattice structure. We\nexplain the observed electronic properties using this model based on a\ncorrelated polaron system. We propose an enhancement effect of the\nDzyaloshinsky-Moriya (DM) interaction between adjoining $1p$ orbitals by the\nextension of the Rashba mechanism of spin-orbit interaction.",
        "positive": "Impact dynamics of granular jets with non-circular cross-sections: Using high-speed photography, we investigate two distinct regimes of the\nimpact dynamics of granular jets with non-circular cross-sections. In the\nsteady-state regime, we observe the formation of thin granular sheets with\nanisotropic shapes and show that the degree of anisotropy increases with the\naspect ratio of the jet's cross-section. Our results illustrate the liquid-like\nbehavior of granular materials during impact and demonstrate that a collective\nhydrodynamic flow emerges from strongly interacting discrete particles. We\ndiscuss the analogy between our experiments and those from the Relativistic\nHeavy Ion Collider (RHIC), where similar anisotropic ejecta from a quark-gluon\nplasma have been observed in heavy-ion impact."
    },
    {
        "anchor": "Force-clamp spectroscopy of reversible bond breakage: We consider reversible breaking of adhesion bonds or folding of proteins\nunder the influence of a constant external force. We discuss the stochastic\nproperties of the unbinding/rebinding events and analyze their mean number and\ntheir variance in the framework of simple two-state models. In the\ncalculations, we exploit the analogy to single molecule fluorescence and\nparticularly between unbinding/rebinding and photon emission events.\nEnvironmental fluctuation models are used to describe deviations from Markovian\nbehavior. The second moment of the event-number distribution is found to be\nvery sensitive to possible exchange processes and can thus be used to identify\ntemporal fluctuations of the transition rates.",
        "positive": "Duality and Sheared Analytic Response in Mechanism-Based Metamaterials: Mechanical metamaterials designed around a zero-energy pathway of\ndeformation, known as a mechanism, have repeatedly challenged the conventional\npicture of elasticity. However, the complex spatial deformations these\nstructures are able to support beyond the uniform mechanism remain largely\nuncharted. Here we present a unified theoretical framework, showing that the\npresence of any uniform mechanism in a two-dimensional structure fundamentally\nchanges its elastic response by admitting a family of non-uniform zero-energy\ndeformations. Our formalism reveals a mathematical duality between these\nstress-free strains, which we term \"sheared analytic modes\" and the supported\nspatial profiles of stress. These modes undergo a transition from bulk periodic\nresponse to evanescent surface response as the Poisson's ratio $\\nu$ of the\nmechanism is tuned through an exceptional point at $\\nu=0$. We suggest a first\napplication of these unusual response properties as a switchable signal\namplifier and filter for use in mechanical circuitry and computation."
    },
    {
        "anchor": "Heterogeneities and Topological Defects in Two-Dimensional Pinned\n  Liquids: We simulate a model of repulsively interacting colloids on a commensurate\ntwo-dimensional triangular pinning substrate where the amount of heterogeneous\nmotion that appears at melting can be controlled systematically by turning off\na fraction of the pinning sites. We correlate the amount of heterogeneous\nmotion with the average topological defect number, time dependent defect\nfluctuations, colloid diffusion, and the form of the van Hove correlation\nfunction. When the pinning sites are all off or all on, the melting occurs in a\nsingle step. When a fraction of the sites are turned off, the melting becomes\nconsiderably broadened and signatures of a two-step melting process appear. The\nnoise power associated with fluctuations in the number of topological defects\nreaches a maximum when half of the pinning sites are removed, and the noise\nspectrum has a pronounced 1/f^\\alpha structure in the heterogeneous regime. We\nfind that regions of high mobility are associated with regions of high\ndislocation densities.",
        "positive": "Nonlinear mechanics of thin frames: The dramatic effect kirigami, such as hole cutting, has on the elastic\nproperties of thin sheets invites a study of the mechanics of thin elastic\nframes under an external load. Such frames can be thought of as modular\nelements needed to build any kirigami pattern. Here we develop the technique of\nelastic charges to address a variety of elastic problems involving thin sheets\nwith perforations, focusing on frames with sharp corners. We find that holes\ngenerate elastic defects (partial disclinations) which act as sources of\ngeometric incompatibility. Numerical and analytic studies are made of three\ndifferent aspects of loaded frames - the deformed configuration itself, the\neffective mechanical properties in the form of force-extension curves and the\nbuckling transition triggered by defects. This allows us to understand generic\nkirigami mechanics in terms of a set of force-dependent elastic charges with\nlong-range interactions."
    },
    {
        "anchor": "Quantitative size-dependent structure and strain determination of CdSe\n  nanoparticles using atomic pair distribution function analysis: The size-dependent structure of CdSe nanoparticles, with diameters ranging\nfrom 2 to 4 nm, has been studied using the atomic pair distribution function\n(PDF) method. The core structure of the measured CdSe nanoparticles can be\ndescribed in terms of the wurtzite atomic structure with extensive stacking\nfaults. The density of faults in the nanoparticles ~50% . The diameter of the\ncore region was extracted directly from the PDF data and is in good agreement\nwith the diameter obtained from standard characterization methods suggesting\nthat there is little surface amorphous region. A compressive strain was\nmeasured in the Cd-Se bond length that increases with decreasing particle size\nbeing 0.5% with respect to bulk CdSe for the 2 nm diameter particles. This\nstudy demonstrates the size-dependent quantitative structural information that\ncan be obtained even from very small nanoparticles using the PDF approach.",
        "positive": "Structural Relaxation of a Gel Modeled by Three Body Interactions: We report a molecular dynamics simulation study of a model gel whose\ninteraction potential is obtained by modifying the three body Stillinger-Weber\nmodel potential for silicon. The modification reduces the average coordination\nnumber, and suppresses the liquid-gas phase coexistence curve. The low density,\nlow temperature equilibrium gel that can thus form exhibits interesting\ndynamical behavior, including compressed exponential relaxation of density\ncorrelations. We show that motion responsible for such relaxation has ballistic\ncharacter, and arises from the motion of chain segments in the gel without the\nrestructuring of the gel network."
    },
    {
        "anchor": "Relationship between Rheology and Structure of Interpenetrating,\n  Deforming and Compressing Microgels: Thermosensitive microgels are widely studied hybrid systems combining\nproperties of polymers and colloidal particles in a unique way. Due to their\ncomplex morphology their interactions and packing, and consequentially the\nviscoelastcity of suspensions made from microgels, are still not fully\nunderstood, in particular under dense packing conditions. Here we study the\nfrequency-dependent linear viscoelastic properties of dense microgel\nsuspensions in conjunction with an analysis of the local particle structure and\nmorphology based on superresolution microscopy. By identifying the dominating\nmechanisms that control the elastic and dissipative response, we propose a\nunified framework that can explain the rheology of these widely studied soft\nparticle assemblies from the onset of elasticity deep into the overpacked\nregime. Our results clarify the transition and coupling between the regime\ndominated by fuzzy shell interactions and the one controlled by the densely\ncross-linked core.",
        "positive": "Textural transformations in islands on free standing Smectic C* liquid\n  crystal films: We report on and analyze the textural transformations in islands, thicker\ncircular domains, floating in very thin free standing chiral Smectic C* liquid\ncrystal films. As an island is growing, an initial pure bend texture of the\nc-director changes into a reversing spiral at a critical size. Another distinct\nspiral texture is induced by changing the boundary condition at the central\npoint defect in the island. To understand these transformations from a pure\nbend island, a linear stability analysis of the c-director free energy is\ndeveloped, which predicts a state diagram for the island. Our observations are\nconsistent with the theoretical phase diagram."
    },
    {
        "anchor": "Shear shock evolution in incompressible soft solids: Nonlinear evolution of shear waves into shocks in incompressible elastic\nmaterials is investigated using the framework of large deformation\nelastodynamics, for a family of loadings and commonly used hyperelastic\nmaterial models. Closed form expressions for the shock formation distance are\nderived and used to construct non-dimensional phase maps that determine regimes\nin which a shock can be realized. These maps reveal the sensitivity of shock\nevolution to the amplitude, shape, and ramp time of the loading, and to the\nelastic material parameters. In light of a recent study (Espindola et al.,\n2017), which hypothesizes that shear shock formation could play a signicant\nrole in Traumatic Brain Injury (TBI), application to brain tissue is considered\nand it is shown that the size matters in TBI research. Namely, for realistic\nloadings, smaller brains are less susceptible to formation of shear shocks.\nFurthermore, given the observed sensitivity to the imparted waveform and the\nconstitutive properties, it is suggested that the non-dimensional maps can\nguide the design of protective structures by determining the combination of\nloading parameters, material dimensions, and elastic properties that can avoid\nshock formation.",
        "positive": "Experimental validation of nonextensive scaling law in confined granular\n  media: In this letter, we address the relationship between the statistical\nfluctuations of grain displacements for a full quasistatic plane shear\nexperiment, and the corresponding anomalous diffusion exponent, $\\alpha$. We\nexperimentally validate a particular case of the so-called Tsallis-Bukman\nscaling law, $\\alpha = 2 / (3 - q)$, where $q$ is obtained by fitting the\nprobability density function (PDF) of the measured fluctuations with a\n$q$-Gaussian distribution, and the diffusion exponent is measured independently\nduring the experiment. Applying an original technique, we are able to evince a\ntransition from an anomalous diffusion regime to a Brownian behavior as a\nfunction of the length of the strain-window used to calculate the displacements\nof grains in experiments. The outstanding conformity of fitting curves to a\nmassive amount of experimental data shows a clear broadening of the fluctuation\nPDFs as the length of the strain-window decreases, and an increment in the\nvalue of the diffusion exponent - anomalous diffusion. Regardless of the size\nof the strain-window considered in the measurements, we show that the\nTsallis-Bukman scaling law remains valid, which is the first experimental\nverification of this relationship for a classical system at different diffusion\nregimes. We also note that the spatial correlations show marked similarities to\nthe turbulence in fluids, a promising indication that this type of analysis can\nbe used to explore the origins of the macroscopic friction in confined granular\nmaterials."
    },
    {
        "anchor": "Macroscopic Discontinuous Shear Thickening vs Local Shear Jamming in\n  Cornstarch: We study the emergence of discontinuous shear-thickening (DST) in cornstarch,\nby combining macroscopic rheometry with local Magnetic Resonance Imaging (MRI)\nmeasurements. We bring evidence that macroscopic DST is observed only when the\nflow separates into a low-density flowing and a high-density jammed region. In\nthe shear-thickened steady state, the local rheology in the flowing region, is\nnot DST but, strikingly, is often shear-thinning. Our data thus show that the\nstress jump measured during DST, in cornstach, does not capture a secondary,\nhigh-viscosity branch of the local steady rheology, but results from the\nexistence of a shear jamming limit at volume fractions quite significantly\nbelow random close packing.",
        "positive": "Tension-dependent transverse buckles and wrinkles in twisted elastic\n  sheets: We investigate with experiments the twist induced transverse buckling\ninstabilities of an elastic sheet of length $L$, width $W$, and thickness $t$,\nthat is clamped at two opposite ends while held under a tension $T$. Above a\ncritical tension $T_\\lambda$ and critical twist angle $\\eta_{tr}$, we find that\nthe sheet buckles with a mode number $n \\geq 1$ transverse to the axis of\ntwist. Three distinct buckling regimes characterized as clamp-dominated,\nbendable, and stiff are identified, by introducing a bendability length $L_B$\nand a clamp length $L_{C}(<L_B)$. In the stiff regime ($L>L_B$), we find that\nmode $n=1$ develops above $\\eta_{tr} \\equiv \\eta_S \\sim (t/W) T^{-1/2}$,\nindependent of $L$. In the bendable regime $L_{C}<L<L_B$, $n=1$ as well as $n >\n1$ occur above $\\eta_{tr} \\equiv \\eta_B \\sim \\sqrt{t/L}T^{-1/4}$. Here, we find\nthe wavelength $\\lambda_B \\sim \\sqrt{Lt}T^{-1/4}$, when $n > 1$. These scalings\nagree with those derived from a covariant form of the F\\\"oppl-von K\\'arm\\'an\nequations, however, we find that the $n=1$ mode also occurs over a surprisingly\nlarge range of $L$ in the bendable regime. Finally, in the clamp-dominated\nregime ($L < L_c$), we find that $\\eta_{tr}$ is higher compared to $\\eta_B$ due\nto additional stiffening induced by the clamped boundary conditions."
    },
    {
        "anchor": "Transferable Coarse-Grained Model for Methacrylate-Based Copolymers: A versatile and transferable coarse-grained (CG) model was developed to\ninvestigate the self-assembly of two ubiquitous methacrylate-based copolymers:\npoly(ethylene oxide-b-methylmethacrylate) (PEO-b-PMMA) and poly(ethylene\noxide-b-butylmethacrylate) (PEO-b-PBMA). We derive effective CG potentials that\ncan reproduce their behaviour in aqueous and organic polymer solutions, pure\ncopolymer systems, and at the air-water interface following a hybrid\nstructural-thermodynamic approach, which incorporates macroscopic and\natomistic-level information. The parameterization of the intramolecular CG\npotentials results from matching the average probability distributions of\nbonded degrees of freedom for chains in solution and in pure polymer systems\nwith those obtained from atomistic simulations. Potential energy functions for\nthe description of effective intra- and intermolecular interactions are elected\nto be fully compatible with the MARTINI force-field. The optimized models allow\nfor an accurate prediction of the structural properties of a number of\nmethacrylate-based copolymers of different length and at different\nthermodynamic state points. In addition, we propose a single-segment model for\ntetrahydrofuran (THF), an organic solvent commonly used in methacrylate-based\npolymer processing. This model exhibits a fluid phase behaviour qualitatively\nclose to that predicted by more sophisticated molecular models and can\nreproduce the experimental free energy of transfer between water and octanol.",
        "positive": "Molecular dynamics simulations of the Johari-Goldstein relaxation in a\n  molecular liquid: Molecular dynamics simulations (mds) were carried out to investigate the\nreorientational motion of a rigid (fixed bond length), asymmetric diatomic\nmolecule in the liquid and glassy states. In the latter the molecule reorients\nvia large-angle jumps, which we identify with the Johari-Goldstein (JG)\ndynamics. This relaxation process has a broad distribution of relaxation times,\nand at least deeply in the glass state, the mobility of a given molecule\nremains fixed over time; that is, there is no dynamic exchange among molecules.\nInterestingly, the JG relaxation time for a molecule does not depend on the\nlocal density, although the non-ergodicity factor is weakly correlated with the\npacking efficiency of neighboring molecules. In the liquid state the frequency\nof the JG process increases significantly, eventually subsuming the slower\nalpha-relaxation. This evolution of the JG-motion into structural relaxation\nunderlies the correlation of many properties of the JG- and alpha-dynamics."
    },
    {
        "anchor": "Phase equilibria in stratified thin liquid films stabilized by colloidal\n  particles: Phase equilibria between regions of different thickness in thin liquid films\nstabilized by colloidal particles are investigated using a\nquasi-two-dimensional thermodynamic formalism. Appropriate equilibrium\nconditions for the film tension, normal pressure, and chemical potential of the\nparticles in the film are formulated, and it is shown that the relaxation of\nthese parameters occurs consecutively on three distinct time scales. Film\nstratification is described quantitatively for a hard-sphere suspension using a\nMonte-Carlo method to evaluate thermodynamic equations of state. Coexisting\nphases are determined for systems in constrained- and full-equilibrium states\nthat correspond to different stages of film relaxation.",
        "positive": "Friction-controlled entropy-stability competition in granular systems: Using cyclic shear to drive a two dimensional granular system, we determine\nthe structural characteristics for different inter-particle friction\ncoefficients. These characteristics are the result of a competition between\nmechanical stability and entropy, with the latter's effect increasing with\nfriction. We show that a parameter-free maximum-entropy argument alone predicts\nan exponential cell order distribution, with excellent agreement with the\nexperimental observation. We show that friction only tunes the mean cell order\nand, consequently, the exponential decay rate and the packing fraction. We\nfurther show that cells, which can be very large in such systems, are\nshort-lived, implying that our systems are liquid-like rather than glassy."
    },
    {
        "anchor": "Phase Transitions in Soft Matter Induced by Selective Solvation: We review our recent studies on selective solvation effects in phase\nseparation in polar binary mixtures with a small amount of solutes. Such\nhydrophilic or hydrophobic particles are preferentially attracted to one of the\nsolvent components. We discuss the role of antagonistic salt composed of\nhydrophilic and hydrophobic ions, which undergo microphase separation at\nwater-oil interfaces leading to mesophases. We then discuss phase separation\ninduced by a strong selective solvent above a critical solute density np, which\noccurs far from the solvent coexistence curve. We also give theories of ionic\nsurfactant systems and weakly ionized polyelectrolytes including solvation\namong charged particles and polar molecules. We point out that the Gibbs\nformula for the surface tension needs to include an electrostatic contribution\nin the presence of an electric double layer.",
        "positive": "Anomalous temperature dependence of surface tension and capillary waves\n  at liquid gallium: The temperature dependence of surface tension \\gamma(T) at liquid gallium is\nstudied theoretically and experimentally using light scattering from capillary\nwaves. The theoretical model based on the Gibbs thermodynamics relates the\ntemperature derivative of \\gamma to the surface excess entropy -\\Delta S.\nAlthough capillary waves contribute to the surface entropy with a positive sign\nthe effect of dipole layer on \\Delta S is negative. Experimental data collected\nat a free Ga surface in the temperature range from 30 to 160 C show that the\ntemperature derivative of the tension changes sign near 100 C."
    },
    {
        "anchor": "On the dissipative effects in the electron transport through conducting\n  polymer nanofibers: Here, we study the effects of stochastic nuclear motions on the electron\ntransport in doped polymer fibers assuming the conducting state of the\nmaterial. We treat conducting polymers as granular metals and apply the quantum\ntheory of conduction in mesoscopic systems to describe the electron transport\nbetween the metalliclike granules. To analyze the effects of nuclear motions we\nmimic them by the phonon bath, and we include the electron-phonon interactions\nin consideration. Our results show that the phonon bath plays a crucial part in\nthe intergrain electron transport at moderately low and room temperatures\nsuppressing the original intermediate state for the resonance electron\ntunneling, and producing new states which support the electron transport.",
        "positive": "Coupling between membrane tilt-difference and dilation: a new ``ripple''\n  instability and multiple crystalline inclusions phases: A continuum Landau theory for the micro-elasticity of membranes is discussed,\nwhich incorporates a coupling between the bilayer thickness variation and the\ndifference in the two monolayers' tilts. This coupling stabilizes a new phase\nwith a rippled micro-structure. Interactions among membrane inclusions combine\na dilation-induced attraction and a tilt-difference-induced repulsion that\nyield 2D crystal phases, with possible coexistence of different lattice\nspacings for large couplings. Inclusions favoring crystals are those with\neither a long-convex or a short-concave hydrophobic core."
    },
    {
        "anchor": "Enhanced transport of ions by tuning surface properties of the\n  nanochannel: We revisit the theory of ion transport in parallel-plate channels and also\ndiscuss how the wettability of a solid and the mobility of adsorbed surface\ncharges impact the transport of ions. It is shown that depending on the ratio\nof the electrostatic disjoining pressure to the excess osmotic pressure at the\nwalls two different regimes occur. In the thick channel regime this ratio is\nsmall and the channel effectively behaves as thick, even when the diffuse\nlayers strongly overlap. The latter is possible for highly charged channels\nonly. In the thin channel regime the disjoining pressure is comparable to the\nexcess osmotic pressure at the wall, which implies relatively weakly charged\nwalls. We derive simple expressions for the mean conductivity of the channel in\nthese two regimes, highlighting the role of electrostatic and\nelectro-hydrodynamic boundary conditions. Our theory provides a simple\nexplanation of the high conductivity observed experimentally in hydrophilic\nchannels, and allows one to obtain rigorous bounds on its attainable value and\nscaling with salt concentration. Our results also show that further dramatic\namplification of conductivity is possible if hydrophobic slip is involved, but\nonly in the thick channel regime provided the walls are sufficiently highly\ncharged and the most of adsorbed charges are immobile. However, for weakly\ncharged surfaces the massive conductivity amplification due to hydrodynamic\nslip is impossible in both regimes. Interestingly, in this case the moderate\nslip-driven contribution to conductivity can monotonously decrease with the\nfraction of immobile adsorbed charges. These results provide a framework for\ntuning the conductivity of nanochannels by adjusting their surface properties\nand bulk electrolyte concentrations.",
        "positive": "Rotational averaging-out gravitational sedimentation of colloidal\n  dispersions and phenomena: We report on the differences between colloidal systems left to evolve in the\nearth's gravitational field and the same systems for which a slow continuous\nrotation averaged out the effects of particle sedimentation on a distance scale\nsmall compared to the particle size. Several systems of micron-sized colloidal\nparticles were studied: a hard sphere fluid, colloids interacting via\nlong-range electrostatic repulsions above the freezing volume fraction, an\noppositely charged colloidal system close to either gelation and/or\ncrystallization, colloids with a competing short-range depletion attraction and\na long-range electrostatic repulsion, colloidal dipolar chains, and colloidal\ngold platelets under conditions where they formed stacks. Important differences\nin the structure formation were observed between the experiments where the\nparticles were allowed to sediment and those where sedimentation was averaged\nout. For instance, in the case of colloids interacting via long-range\nelectrostatic repulsions, an unusual sequence of\ndilute-Fluid/dilute-Crystal/dense-Fluid/dense-Crystal phases was observed\nthroughout the suspension under the effect of gravity, related to the volume\nfraction dependence of the colloidal interactions, whereas the system stayed\nhomogeneously crystallized with rotation. For the oppositely charged colloids,\na gel-like structure was found to collapse under the influence of gravity with\na few crystalline layers grown on top of the sediment, whereas when the\ncolloidal sedimentation was averaged out, the gel completely transformed into\ncrystallites that were oriented randomly throughout the sample. Rotational\naveraging out gravitational sedimentation is an effective and cheap way to\nestimate the importance of gravity for colloidal self-assembly processes."
    },
    {
        "anchor": "Impact of BaTiO$_3$ nanoparticles on phase transitions and dynamics in\n  nematic liquid crystal - temperature and pressure studies: Broadband dielectric spectroscopy (BDS) of pure 5OCB and nanocolloids\nconsisting of 5OCB and paraelectric or ferroelectric BaTiO${_3}$ nanoparticles\n(NPs) was performed on varying pressure or temperature. We found strong impact\nof NPs on static and dynamic phase behavior. In particular, strongest effects\non pretransitional behavior were observed for a relatively low concentration of\nNPs which we attribute to the NPs-induced disorder. Paramagnetic or\nferromagnetic character of NPs did not significantly influence measurements.\nHowever, several features measured using temperature or pressure path in\nnanocolloids where significantly different, contrary to the observed behaviour\nin pure LC compounds. Dynamical properties were tested using the FDSE\n(fractional Debye-Stokes-Einstein) relation, yielding the fractional\ncoefficient S = 0.71 and S = 0.3 for the temperature and pressure path,\nrespectively.",
        "positive": "Controlling the Interactions between Soft Colloids via Surface\n  Adsorption: By employing monomer-resolved computer simulations and analytical\nconsiderations based on polymer scaling theory, we analyze the conformations\nand interactions of multiarm star polymers strongly adsorbed on a smooth,\ntwo-dimensional plane. We find a stronger stretching of the arms as well as a\nstronger repulsive, effective interaction than in the three dimensional case.\nIn particular, the star size scales with the number of arms $f$ as $\\sim\nf^{1/4}$ and the effective interaction as $\\sim f^{2}$, as opposed to $\\sim\nf^{1/5}$ and $\\sim f^{3/2}$, respectively, in three dimensions. Our results\ndemonstrate the dramatic effect that geometric confinement can have on the\neffective interactions and the subsequent correlations of soft colloids in\ngeneral, for which the conformation can be altered as a result of geometrical\nconstraints imposed on them."
    },
    {
        "anchor": "Pickering emulsions with alpha-cyclodextrin inclusions: Structure and\n  thermal stability: This paper explores structural, interfacial and thermal properties of two\ntypes of Pickering emulsions containing alpha-cyclodextrin inclusion complexes:\non one hand, emulsions were obtained between aqueous solutions of\nalpha-cyclodextrin and different oils (fatty acids, olive oil, silicone oil)\nand on the other hand, emulsions were obtained between these oils, water and\nmicro or nano-platelet suspensions with inclusion complexes of\nhydrophobically-modified polysaccharides. The emulsions exhibit versatile\nproperties according to the molecular architecture of the oils. Experiments\nwere performed by microcalorimetry, X-ray diffraction and confocal microscopy.\nThe aptitude of oil molecules to be threaded in alpha-cyclodextrin cavity is a\ndetermining parameter in emulsification and thermal stability. The heat flow\ntraces and images showed dissolution, cooperative melting and de- threading of\ninclusion complexes which take place progressively, ending at high\ntemperatures, close or above 100{\\deg}C. Another important feature observed in\nthe emulsions with micro-platelets is the partial substitution of the guest\nmolecules occurring at room temperature at the oil/water interfaces without\ndissolution, possibly by a diffusion mechanism of the oil. Accordingly, the\ndissolution and the cooperative melting temperatures of the inclusion crystals\nchanged, showing marked differences upon the type of guest molecules. The\nenthalpies of dissolution of crystals were measured and compared with soluble\ninclusions.",
        "positive": "Tunneling Dynamics of Bose-Einstein Condensates with Feshbach Resonances: We study tunneling dynamics of atomic pairs in Bose-Einstein condensates with\nFeshbach resonances. It is shown that the tunneling of the atomic pairs depends\non not only the tunneling coupling between the atomic condensate and the\nmolecular condensate, but also the inter-atomic nonlinear interactions and the\ninitial number of atoms in these condensates. It is found that in addition to\noscillating tunneling current between the atomic condensate and the molecular\ncondensate, the nonlinear atomic-pair tunneling dynamics sustains a self-locked\npopulation imbalance: macroscopic quantum self-trapping effect. Influence of\ndecoherence induced by non-condensate atoms on tunneling dynamics is\ninvestigated. It is shown that decoherence suppresses atomic-pair tunneling."
    },
    {
        "anchor": "Pressure-deformation relations of elasto-capillary drops (droploons) on\n  capillaries: Simple analytical relations for predicting pressure-deformation relations of\ndrops/bubbles on capillaries with elastocapillary interfaces confirmed by\nSurface Evolver simulations.",
        "positive": "PyStokes: phoresis and Stokesian hydrodynamics in Python: We present a modular Python library for computing many-body hydrodynamic and\nphoretic interactions between spherical active particles in suspension, when\nthese are given by solutions of the Stokes and Laplace equations. Underpinning\nthe library is a grid-free methodology that combines dimensionality reduction,\nspectral expansion, and Ritz-Galerkin discretization, thereby reducing the\ncomputation to the solution of a linear system. The system can be solved\nanalytically as a series expansion or numerically at a cost quadratic in the\nnumber of particles. Suspension-scale quantities like fluid flow, entropy\nproduction, and rheological response are obtained at a small additional cost.\nThe library is agnostic to boundary conditions and includes, amongst others,\nconfinement by plane walls or liquid-liquid interfaces. The use of the library\nis demonstrated with six fully coded examples simulating active phenomena of\ncurrent experimental interest."
    },
    {
        "anchor": "Soft yet sharp interfaces in a vertex model of confluent tissue: How can dense biological tissue maintain sharp boundaries between coexisting\ncell populations? We explore this question within a simple vertex model for\ncells, focusing on the role of topology and tissue surface tension. We show\nthat the ability of cells to independently regulate adhesivity and tension,\ntogether with neighbor-based interaction rules, lets them support strikingly\nunusual interfaces. In particular, we show that mechanical- and\nfluctuation-based measurements of the effective surface tension of a cellular\naggregate yield different results, leading to mechanically soft interfaces that\nare nevertheless extremely sharp.",
        "positive": "Large-scale chirality in an active layer of microtubules and kinesin\n  motor proteins: During the early developmental process of organisms, the formation of the\nleft-right laterality requires a subtle mechanism, as it is associated with\nother principal body axes. Any inherent chiral feature in an egg cell can in\nprincipal trigger this spontaneous breaking of chiral symmetry. Individual\nmicrotubules, major cytoskeletal filaments, are known as chiral objects.\nHowever, to date there lacks convincing evidence of a hierarchical connection\nof the molecular nature of microtubules to large-scale chirality, particularly\nat the length scale of an entire cell. Here we assemble an in-vitro active\nlayer, consisting of microtubules and kinesin motor proteins, on a glass\nsurface. Upon inclusion of methyl cellulose, the layered system exhibits a\nlong-range active nematic phase, characterized by the global alignment of\ngliding MTs. This nematic order spans over the entire system size in the\nmillimeter range and, remarkably, allows hidden collective chirality to emerge\nas counterclockwise global rotation of the active MT layer. The analysis based\non our theoretical model suggests that the emerging global nematic order\nresults from the local alignment of MTs, stabilized by methyl cellulose. It\nalso suggests that the global rotation arises from the MTs' intrinsic\ncurvature, leading to preferential handedness. Given its flexibility, this\nlayered in-vitro cytoskeletal system enables the study of membranous protein\nbehavior responsible for important cellular developmental processes."
    },
    {
        "anchor": "Lateral diffusion of receptor-ligand bonds in membrane adhesion zones:\n  Effect of thermal membrane roughness: The adhesion of cells is mediated by membrane receptors that bind to\ncomplementary ligands in apposing cell membranes. It is generally assumed that\nthe lateral diffusion of mobile receptor-ligand bonds in membrane-membrane\nadhesion zones is slower than the diffusion of unbound receptors and ligands.\nWe find that this slowing down is not only caused by the larger size of the\nbound receptor-ligand complexes, but also by thermal fluctuations of the\nmembrane shape. We model two adhering membranes as elastic sheets pinned\ntogether by receptor-ligand bonds and study the diffusion of the bonds using\nMonte Carlo simulations. In our model, the fluctuations reduce the bond\ndiffusion constant in planar membranes by a factor close to 2 in the\nbiologically relevant regime of small bond concentrations.",
        "positive": "A Scaling Hypothesis for Modulated Systems: We propose a scaling hypothesis for pattern-forming systems in which\nmodulation of the order parameter results from the competition between a\nshort-ranged interaction and a long-ranged interaction decaying with some power\n$\\alpha$ of the inverse distance. With L being a spatial length characterizing\nthe modulated phase, all thermodynamic quantities are predicted to scale like\nsome power of L. The scaling dimensions with respect to L only depend on the\ndimensionality of the system d and the exponent \\alpha. Scaling predictions are\nin agreement with experiments on ultra-thin ferromagnetic films and\ncomputational results. Finally, our scaling hypothesis implies that, for some\nrange of values \\alpha>d, Inverse-Symmetry-Breaking transitions may appear\nsystematically in the considered class of frustrated systems."
    },
    {
        "anchor": "Spiraling Solitons: a Continuum Model for Dynamical Phyllotaxis and\n  Beyond: A novel, protean, topological soliton has recently been shown to emerge in\nsystems of repulsive particles in cylindrical geometries, whose statics is\ndescribed by the number-theoretical objects of phyllotaxis. Here we present a\nminimal and local continuum model that can explain many of the features of the\nphyllotactic soliton, such as locked speed, screw shift, energy transport and,\nfor Wigner crystal on a nanotube, charge transport. The treatment is general\nand should apply to other spiraling systems. Unlike e.g. Sine-Gornon-like\nsystems, our solitons can exist between non-degenerate structure, imply a power\nflow through the system, dynamics of the domains it separates; we also predict\npulses, both static and dynamic. Applications include charge transport in\nWigner Crystals on nanotubes or A- to B-DNA transitions.",
        "positive": "Relative humidity in droplet and airborne transmission of disease: A large number of infectious diseases is transmitted by respiratory droplets.\nHow long these droplets persist in the air, how far they can travel, and how\nlong the pathogens they might carry survive are all decisive factors for the\nspread of droplet-borne diseases. The subject is extremely multifaceted and its\naspects range across different disciplines, yet most of them have only seldom\nbeen considered in the physics community. In this review, we discuss the\nphysical principles that govern the fate of respiratory droplets and any\nviruses trapped inside them, with a focus on the role of relative humidity.\nImportantly, low relative humidity -- as encountered, for instance, indoors\nduring winter and inside aircraft -- facilitates evaporation and keeps even\ninitially large droplets suspended in air as aerosol for extended periods of\ntime. What is more, relative humidity affects the stability of viruses in\naerosol through several physical mechanisms such as efflorescence and\ninactivation at the air-water interface, whose role in virus inactivation\nnonetheless remains poorly understood. Elucidating the role of relative\nhumidity in the droplet spread of disease would permit us to design preventive\nmeasures that could aid in reducing the chance of transmission, particularly in\nindoor environment."
    },
    {
        "anchor": "Reversible stretching of homopolymers and random heteropolymers: We have analyzed the equilibrium response of chain molecules to stretching.\nFor a homogeneous sequence of monomers, the induced transition from compact\nglobule to extended coil below the $\\theta$-temperature is predicted to be\nsharp. For random sequences, however, the transition may be smoothed by a\nprevalence of necklace-like structures, in which globular regions and coil\nregions coexist in a single chain. As we show in the context of a random\ncopolymer, preferential solvation of one monomer type lends stability to such\nstructures. The range of stretching forces over which necklaces are stable is\nsensitive to chain length as well as sequence statistics.",
        "positive": "DNA Bubble Life Time in Denaturation: We have investigated the denaturation bubble life time for a homogeneous as\nwell as for a heterogeneous DNA within a Poland-Scheraga model. It is shown\nthat at criticality the bubble life time for a homogeneous DNA is finite\nprovided that the loop entropic exponent c>2 and has a scaling dependence on\nDNA length for c<2. Heterogeneity in the thermodynamical limit makes the bubble\nlife time infinite for any entropic exponent."
    },
    {
        "anchor": "Helical Packings and Phase Transformations of Soft Spheres in Cylinders: The phase behavior of helical packings of thermoresponsive microspheres\ninside glass capillaries is studied as a function of volume fraction. Stable\npackings with long-range orientational order appear to evolve abruptly to\ndisordered states as particle volume fraction is reduced, consistent with\nrecent hard sphere simulations. We quantify this transition using correlations\nand susceptibilities of the orientational order parameter psi_6. The emergence\nof coexisting metastable packings, as well as coexisting ordered and disordered\nstates, is also observed. These findings support the notion of phase\ntransition-like behavior in quasi-1D systems.",
        "positive": "Stick-slip instabilities in sheared granular flow: the role of friction\n  and acoustic vibrations: We propose a theory of shear flow in dense granular materials. A key\ningredient of the theory is an effective temperature that determines how the\nmaterial responds to external driving forces such as shear stresses and\nvibrations. We show that, within our model, friction between grains produces\nstick-slip behavior at intermediate shear rates, even if the material is\nrate-strengthening at larger rates. In addition, externally generated acoustic\nvibrations alter the stick-slip amplitude, or suppress stick-slip altogether,\ndepending on the pressure and shear rate. We construct a phase diagram that\nindicates the parameter regimes for which stick-slip occurs in the presence and\nabsence of acoustic vibrations of a fixed amplitude and frequency. These\nresults connect the microscopic physics to macroscopic dynamics, and thus\nproduce useful information about a variety of granular phenomena including\nrupture and slip along earthquake faults, the remote triggering of\ninstabilities, and the control of friction in material processing."
    },
    {
        "anchor": "Near-surface rheology and hydrodynamic boundary condition of semi-dilute\n  polymer solutions: Understanding confined flows of complex fluids requires simultaneous access\nto the mechanical behaviour of the liquid and the boundary condition at the\ninterfaces. Here, we use evanescent wave microscopy to investigate near-surface\nflows of semi-dilute, unentangled polyacrylamide solutions. By using both\nneutral and anionic polymers, we show that monomer charge plays a key role in\nconfined polymer dynamics. For solutions in contact with glass, the neutral\npolymers display chain-sized adsorbed layers, while a shear-rate-dependent\napparent slip length is observed for anionic polymer solutions. The slip\nlengths measured at all concentrations collapse onto a master curve when scaled\nusing a simple two-layer depletion model with non-Newtonian viscosity. A\ntransition from an apparent slip boundary condition to a chain-sized adsorption\nlayer is moreover highlighted by screening the charge with additional salt in\nthe anionic polymer solutions. We anticipate that our study will be a starting\npoint for more complex studies relating the polymer dynamics at interfaces to\ntheir chemical and physical composition.",
        "positive": "Toward a better understanding of activation volume and dynamic\n  decoupling of glass-forming liquids under compression: We theoretically investigate physical properties of the pressure-induced\nactivation volume and dynamic decoupling of ternidazole, glycerol, and probucol\nby the Elastically Collective Nonlinear Langevin Equation theory. Based on the\npredicted temperature dependence of activated relaxation under various\ncompression, the activation volume is determined to characterize effects of\npressure on molecular dynamics of materials. We find that the decoupling of the\nstructural relaxation time of compressed systems from their bulk uncompressed\nvalue is governed by the power-law rule. The decoupling exponent exponentially\ngrows with pressure below 2 GPa. The decoupling exponent and activation volume\nare intercorrelated and have a connection with the differential activation free\nenergy. We numerically and mathematically analyze relationships among these\nquantities to explain many results in previous experiments and simulations."
    },
    {
        "anchor": "Role of cohesion in the formation of kink wave fronts in vibrofluidized\n  granular materials: The formation of kink wave fronts (KWFs) in a quasi-two-dimensional granular\nsystem is investigated numerically with a focus on the role of cohesive\ninteractions between individual particles. The cohesive particle-particle\ninteraction is achieved through tuning the velocity-dependent coefficient of\nrestitution, based on an analytical model introduced recently. A comparison\nwith experimental results indicates that the threshold for the emergence of\ntraveling KWFs matches the regime in which the center of mass height of the\ngranular layers fluctuates with a period that triples the vibration period.\nFurther comparisons between dry and wet granular dynamics reveal that KWFs are\nmore pronounced in wet granular layers because of enhanced collective motion\ninduced by cohesion.",
        "positive": "Spinodal Phase Separation in Liquid Films with Quenched Disorder: We study spinodal phase separation in unstable thin liquid films on\nchemically disordered substrates via simulations of the thin-film equation. The\ndisorder is characterized by immobile patches of varying size and Hamaker\nconstant. The effect of disorder is pronounced in the early stages\n(amplification of fluctuations), remains during the intermediate stages and\nvanishes in the late stages (domain growth). These findings are in contrast to\nthe well-known effects of quenched disorder in usual phase-separation\nprocesses, viz., the early stages remain undisturbed and domain growth is\nslowed down in the asymptotic regime. We also address the inverse problem of\nestimating disorder by thin-film experiments."
    },
    {
        "anchor": "Dissipative Particle Dynamics for Directed Self-Assembly of Block\n  Copolymers: The dissipative particle dynamics (DPD) simulation method has been shown to\nbe a promising tool to study self-assembly of soft matter systems. In\nparticular, it has been used to study block copolymer (BCP) self-assembly.\nHowever, previous parametrizations of this model are not able to capture most\nof the rich phase behaviors of block copolymers in thin films nor in directed\nself-assembly (chemoepitaxy or graphoepitaxy). Here we extend the applicability\nof the DPD method for BCPs to make it applicable to thin films and directed\nself-assembly. Our new reparametrization is able to reproduce the bulk phase\nbehavior, but also manages to predict thin film structures obtained\nexperimentally from chemoepitaxy or graphoepitaxy. A number of different\ncomplex structures, such as bilayer nanomeshes, 90{\\deg} bend structures,\ncircular cylinders/lamellae and Frank-Kasper phases directed by trenches, post\narrays or chemically patterned substrate have all been reproduced in this work.\nThis reparametrized DPD model should serves as a powerful tool to predict BCP\nself-assembly, especially in some complex systems where it is difficult to\nimplement SCFT.",
        "positive": "Differences in tension and compression in the nonlinearly elastic\n  bending of beams: The classical flexure problem of non-linear incompressible elasticity is\nrevisited for elastic materials whose mechanical response is different in\ntension and compression---the so-called bimodular materials. The flexure\nproblem is chosen to investigate this response since the two regions, one of\ntension and one of compression, can be identified easily using simple\nintuition. Two distinct problems are considered: the first is where the stress\nis assumed continuous across the boundary of the two regions, which assumption\nhas a sound physical basis. The second problem considered is more speculative:\nit is where discontinuities of stress are allowed. It is shown that such\ndiscontinuities are necessarily small for many applications, but might\nnonetheless provide an explanation for the damage incurred by repeated flexure.\nSome experimental evidence of the possibility of bimodularity in elastomers is\nalso presented."
    },
    {
        "anchor": "Ideally Glassy Hydrogen Bonded Networks: The axiomatic theory of ideally glassy networks, which has proved effective\nin describing phase diagrams and properties of chalcogenide and oxide glasses\nand their foreign interfaces, is broadened here to include intermolecular\ninteractions in hydrogen-bonded polyalcohols such as glycerol, monosaccharides\n(glucose), and the optimal bioprotective hydrogen-bonded disaccharide networks\nformed from trehalose. The methods of Lagrangian mechanics and Maxwellian\nscaffolds are useful at the molecular level when bonding hierarchies are\ncharacterized by constraint counting similar to the chemical methods used by\nHuckel and Pauling. Whereas Newtonian molecular dynamical methods are useful\nfor simulating large-scale interactions for times of order 10 ps, constraint\ncounting describes network properties on glassy (almost equilibrated) time\nscales, which may be of cosmological order for oxide glasses, or years for\ntrehalose. The ideally glassy network of trehalose may consist of extensible\ntandem sandwich arrays.",
        "positive": "The fluidic memristor: collective phenomena in elastohydrodynamic\n  networks: Fluid flow networks are ubiquitous and can be found in a broad range of\ncontexts, from human-made systems such as water supply networks to living\nsystems like animal and plant vasculature. In many cases, the elements forming\nthese networks exhibit a highly non-linear pressure-flow relationship. Although\nwe understand how these elements work individually, their collective behavior\nremains poorly understood. In this work, we combine experiments, theory, and\nnumerical simulations to understand the main mechanisms underlying the\ncollective behavior of soft flow networks with elements that exhibit negative\ndifferential resistance. Strikingly, our theoretical analysis and experiments\nreveal that a minimal network of nonlinear resistors, which we have termed a\n`fluidic memristor', displays history-dependent resistance. This new class of\nelement can be understood as a collection of hysteresis loops that allows this\nfluidic system to store information. Our work provides insights that may inform\nnew applications of fluid flow networks in soft materials science, biomedical\nsettings, and soft robotics, and may also motivate new understanding of the\nflow networks involved in animal and plant physiology."
    },
    {
        "anchor": "Characterizing nonaffinity upon decompression of soft-sphere packings: Athermal elastic moduli of soft sphere packings are known to exhibit\nuniversal scaling properties near the unjamming point, most notably the\nvanishing of the shear-to-bulk moduli ratio $G/B$ upon decompression.\nInterestingly, the smallness of $G/B$ stems from the large nonaffinity of\ndeformation-induced displacements under shear strains, compared to\ninsignificant nonaffinity of displacements under compressive strains. In this\nwork we show using numerical simulations that the relative weights of the\naffine and nonaffine contributions to the bulk modulus, and their dependence on\nthe proximity to the unjamming point, can qualitatively differ between\ndifferent models that feature the same generic unjamming phenomenology. In\ncanonical models of unjamming we observe that the ratio of the nonaffine to\ntotal bulk moduli $B_{na}/B$ approaches a constant upon decompression, while in\nother, less well-studied models, it vanishes. We show that the vanishing of\n$B_{na}/B$ in non-canonical models stems from the emergence of an invariance of\nnet (zero) forces on the constituent particles to compressive strains at the\nonset of unjamming. We provide a theoretical scaling analysis that fully\nexplains our numerical observations, and allows to predict the scaling behavior\nof $B_{na}/B$ upon unjamming, given the functional form of the pairwise\ninteraction potential.",
        "positive": "Redirection of a crack driven by viscous fluid: As shown by Wrobel et al. (2017), the hydraulically induced tangential\ntraction on fracture walls changes local displacement and stress fields. This\nresulted in the formulation of a new hydraulic fracture (HF) propagation\ncondition based on the critical value of the energy release rate that accounts\nfor the hydraulically-induced shear stress. Therefore it is clear that the\ncrack direction criteria, which depend on the tip distributions of the stress\nand strain fields, need to be changed. We analyse the two commonly used\ncriteria, one based on the maximum circumferential stress (MCS) and another -\non the minimum strain energy density (MSED). We show that the impact of the\nhydraulically induced shear stress on the direction of the crack propagation is\nnegligible in the case of large material resistance to fracture, while for\nsmall toughness the effect is significant. Moreover, values of the redirection\nangles, corresponding to the so-called viscosity dominated regime, depend\ndramatically on the ratios of the stress intensity factors."
    },
    {
        "anchor": "Coexistences of lamellar phases in ternary surfactant solutions: We theoretically investigate the coexistences of lamellar phases both in\nbinary and ternary surfactant solutions. The previous free energy of a lamellar\nstack is extended to take into account the translational entropy of membrane\nsegments. The obtained phase diagram for binary surfactant solutions\n(surfactant/water mixtures) shows a phase separation between two lamellar\nphases and also exhibits a critical point. For lamellar phases in ternary\nsurfactant solutions (surfactant/surfactant/water mixtures), we explore\npossible phase behaviors and show that the phase diagrams exhibit various\nthree-phase regions as well as two-phase regions in which different lamellar\nphases coexist. We also find that finite surface tension suppresses undulation\nfluctuations of membranes and leads to a wider three-phase and two-phase\ncoexistence regions.",
        "positive": "Digital Alchemy for Materials Design: Colloids and Beyond: Starting with the early alchemists, a holy grail of science has been to make\ndesired materials by modifying the attributes of basic building blocks.\nBuilding blocks that show promise for assembling new complex materials can be\nsynthesized at the nanoscale with attributes that would astonish the ancient\nalchemists in their versatility. However, this versatility means that making\ndirect connection between building block attributes and bulk behavior is both\nnecessary for rationally engineering materials, and difficult because building\nblock attributes can be altered in many ways. Here we show how to exploit the\nmalleability of the valence of colloidal nanoparticle \"elements\" to directly\nand quantitatively link building block attributes to bulk behavior through a\nstatistical thermodynamic framework we term \"digital alchemy\". We use this\nframework to optimize building blocks for a given target structure, and to\ndetermine which building block attributes are most important to control for\nself assembly, through a set of novel thermodynamic response functions, moduli\nand susceptibilities. We thereby establish direct links between the attributes\nof colloidal building blocks and the bulk structures they form. Moreover, our\nresults give concrete solutions to the more general conceptual challenge of\noptimizing emergent behaviors in nature, and can be applied to other types of\nmatter. As examples, we apply digital alchemy to systems of truncated\ntetrahedra, rhombic dodecahedra, and isotropically interacting spheres that\nself assemble diamond, FCC, and icosahedral quasicrystal structures,\nrespectively."
    },
    {
        "anchor": "Analytical structure, dynamics, and coarse-graining of a kinetic model\n  of an active fluid: We analyze one of the simplest active suspensions with complex dynamics: a\nsuspension of immotile \"Extensor\" particles that exert active extensile dipolar\nstresses on the fluid in which they are immersed. This is relevant to several\nexperimental systems, such as recently studied tripartite rods that create\nextensile flows by consuming a chemical fuel. We first describe the system\nthrough a Doi-Onsager kinetic theory based on microscopic modeling. This theory\ncaptures the active stresses produced by the particles that can drive\nhydrodynamic instabilities, as well as the steric interactions of rod-like\nparticles that lead to nematic alignment. This active nematic system yields\ncomplex flows and disclination defect dynamics very similar to phenomenological\nLandau-deGennes Q-tensor theories for active nematic fluids, as well as by more\ncomplex Doi-Onsager theories for polar microtubule/motor-protein systems. We\napply the quasi-equilibrium Bingham closure, used to study suspensions of\npassive microscopic rods, to develop a non-standard Q-tensor theory. We\ndemonstrate through simulation that this \"BQ-tensor\" theory gives an excellent\nanalytical and statistical accounting of the suspension's complex dynamics, at\na far reduced computational cost. Finally, we apply the BQ-tensor model to\nstudy the dynamics of Extensor suspensions in circular and bi-concave domains.\nIn circular domains, we reproduce previous results for systems with weak\nnematic alignment, but for strong alignment find novel dynamics with\nactivity-controlled defect production and absorption at the boundaries of the\ndomain. In bi-concave domains, a Fredericks-like transition occurs as the width\nof the neck connecting the two disks is varied.",
        "positive": "Regimes of motion of magnetocapillary swimmers: The dynamics of a triangular magnetocapillary swimmer is studied using the\nlattice Boltzmann method. Performing extensive numerical simulations taking\ninto account the coupled dynamics of the fluid-fluid interface and of magnetic\nparticles floating on it and driven by external magnetic fields we identify\nseveral regimes of the swimmer motion. In the regime of high frequencies the\nswimmer's maximum velocity is centered around the particle's inverse coasting\ntime. Modifying the ratio of surface tension and magnetic forces allows to\nstudy the swimmer propagation in the regime of significantly lower frequencies\nmainly defined by the strength of the magnetocapillary potential. Finally,\nintroducing a constant magnetic contribution in each of the particles in\naddition to their magnetic moment induced by external fields leads to another\nregime characterised by strong in-plane swimmer reorientations that resemble\nexperimental observations."
    },
    {
        "anchor": "Weakly nonlinear dynamics of a chemically active particle near the\n  threshold for spontaneous motion. II. History-dependent motion: We develop a reduced model for the slow unsteady dynamics of an isotropic\nchemically active particle near the threshold for spontaneous motion. Building\non the steady theory developed in part I of this series, we match a weakly\nnonlinear expansion valid on the particle scale with a leading-order\napproximation in a larger-scale unsteady remote region, where the particle acts\nas a moving point source of diffusing concentration. The resulting amplitude\nequation for the velocity of the particle includes a term representing the\ninteraction of the particle with its own concentration wake in the remote\nregion, which can be expressed as a time integral over the history of the\nparticle motion, allowing efficient simulation and theoretical analysis of\nfully three-dimensional unsteady problems. To illustrate how to use the model,\nwe study the effects of a weak force acting on the particle, including the\nstability of the steady states and how the velocity vector realigns towards the\nstable one, neither of which previous axisymmetric and steady models were able\nto capture. This unsteady formulation could also be applied to most of the\nother perturbation scenarios studied in part I as well as the dynamics of\ninteracting active particles.",
        "positive": "Interfaces and Grain Boundaries of Lamellar Phases: Interfaces between lamellar and disordered phases, and grain boundaries\nwithin lamellar phases, are investigated employing a simple Landau free energy\nfunctional. The former are examined using analytic, approximate methods in the\nweak segregation limit, leading to density profiles which can extend over many\nwavelengths of the lamellar phase. The latter are studied numerically and\nexactly. We find a change from smooth chevron configurations typical of small\ntilt angles to distorted omega configurations at large tilt angles in agreement\nwith experiment."
    },
    {
        "anchor": "Tuning Interparticle Hydrogen Bonding in Shear-Jamming Suspensions:\n  Kinetic Effects and Consequences for Tribology and Rheology: The shear-jamming of dense suspensions can be strongly affected by\nmolecular-scale interactions between particles, e.g. by chemically controlling\ntheir propensity for hydrogen bonding. However, hydrogen bonding not only\nenhances interparticle friction, a critical parameter for shear jamming, but\nalso introduces (reversible) adhesion, whose interplay with friction in\nshear-jamming systems has so far remained unclear. Here, we present atomic\nforce microscopy studies to assess interparticle adhesion, its relationship to\nfriction, and how these attributes are influenced by urea, a molecule that\ninterferes with hydrogen bonding. We characterize the kinetics of this process\nwith nuclear magnetic resonance, relating it to the time dependence of the\nmacroscopic flow behavior with rheological measurements. We find that\ntime-dependent urea sorption reduces friction and adhesion, causing a shift in\nthe shear-jamming onset. These results extend our mechanistic understanding of\nchemical effects on the nature of shear jamming, promising new avenues for\nfundamental studies and applications alike.",
        "positive": "Binding cooperativity of membrane adhesion receptors: The adhesion of cells is mediated by receptors and ligands anchored in\napposing membranes. A central question is how to characterize the binding\naffinity of these membrane-anchored molecules. For soluble molecules, the\nbinding affinity is typically quantified by the binding equilibrium constant\nK3D in the linear relation [RL] = K3D [R][L] between the volume concentration\n[RL] of bound complexes and the volume concentrations [R] and [L] of unbound\nmolecules. For membrane-anchored molecules, it is often assumed by analogy that\nthe area concentration of bound complexes [RL] is proportional to the product\n[R][L] of the area concentrations for the unbound receptor and ligand\nmolecules. We show here (i) that this analogy is only valid for two planar\nmembranes immobilized on rigid surfaces, and (ii) that the thermal roughness of\nflexible membranes leads to cooperative binding of receptors and ligands. In\nthe case of flexible membranes, the area concentration [RL] of receptor-ligand\nbonds is proportional to the square of [R][L] for typical lengths and\nconcentrations of receptors and ligands in cell adhesion zones. The cooperative\nbinding helps to understand why different experimental methods for measuring\nthe binding affinity of membrane-anchored molecules have led to values\ndiffering by several orders of magnitude."
    },
    {
        "anchor": "Experimental analysis of single particle deformations and rotations in\n  colloidal and granular systems: Confocal microscopy of fluorescent labeled particles has been used to study\nthe dynamical and structural properties of colloidal and granular matter in\nreal space. Localization algorithms allow for a fully automatized determination\nof the three dimensional positions and translational motions of all constituent\n(spherical) particles in the observed volume. Though, particle deformations or\nrotational motions were hardly addressed. Here we present preparation and image\nprocessing techniques to also extract the deformation and rotational state of\nthe particles. The deformation analysis is worked out for particles with a\nhollow sphere-like fluorescence intensity distribution that are more sensitive\nto small deformations. In the second case of rotations we utilize the angle\ndependence of the light absorption of the incorporated dye molecules to prepare\noptically anisotropic particles in analogy to polarized fluorescence after\nphotobleaching. Rotations of these particles are expressed as intensity\nfluctuations in the confocal images. In contrast to existing methods our\ntechniques do not reduce the quality of the actual particle localization. They\ncan help understanding complex reorganization processes in arrested states of\ncolloidal and granular materials during aging or under external stimuli such as\nshear or compression.",
        "positive": "Reversibility, Pattern Formation and Edge Transport in Active Chiral and\n  Passive Disk Mixtures: We numerically examine mixtures of circularly moving and passive disks as a\nfunction of density and active orbit radius. For low or intermediate densities\nand/or small orbit radii, the system can organize into a reversible partially\nphase separated labyrinth state in which there are no collisions between disks,\nwith the degree of phase separation increasing as the orbit radius increases.\nAs a function of orbit radius, we find a divergence in the number of cycles\nrequired to reach a collision-free steady state at a critical radius, while\nabove this radius the system remains in a fluctuating liquid state. For high\ndensities, the system can organize into a fully phase separated state that is\nmostly reversible, but collisions at the boundaries between the phases lead to\na net transport of disks along the boundary edges in a direction determined by\nthe chirality of the active disk orbits. We map the dynamic phases as a\nfunction of density and orbit radii, and discuss the results in terms of the\nreversible-irreversible transition found in other periodically driven\nnon-thermal systems. We also consider mixtures of circularly driven disks and\nac driven disks where the ac drive is either in or out of phase with the\ncircular motion, and find a rich variety of pattern forming and reentrant\ndisordered phases."
    },
    {
        "anchor": "Aging of CKN: Modulus versus conductivity analysis: It was recently reported that the electrical modulus peaks narrows upon\nannealing of the ionic system CKN [Paluch et al., Phys. Rev. Lett. 110, 015702\n(2013)], which was interpreted as providing evidence of dynamic heterogeneity\nof this glass-forming liquid. An analysis of the same data in terms of the ac\nconductivity shows no shape changes, however. We discuss the relation between\nboth findings and show further that the ac conductivity conforms to the\nprediction of the random barrier model (RBM) at all times during the annealing.",
        "positive": "Layering in Crumpled Sheets: We introduce a toy model of crumpled sheets. We use simulation to show there\nis a first order phase transition in the model, from a disordered dilute phase\nto a mixture with a layered phase."
    },
    {
        "anchor": "Molecular dynamics simulation of the capillary leveling of viscoelastic\n  polymer films: Surface tension-driven flow techniques have recently emerged as an efficient\nmeans of shedding light into the rheology of thin polymer films. Motivated by\nexperimental and theoretical approaches in films bearing a varying surface\ntopography, we present results on the capillary relaxation of a square pattern\nat the free surface of a viscoelastic polymer film, using molecular dynamics\nsimulations of a coarse-grained polymer model. Height profiles are monitored as\na function of time after heating the system above its glass-transition\ntemperature and their time dependence is fitted to the theory of capillary\nleveling. Results show that the viscosity is not constant, but time dependent.\nIn addition to providing a complementary insight about the local inner\nmechanisms, our simulations of the capillary-leveling process therefore probe\nthe viscoelasticity of the polymer and not only its viscosity, in contrast to\nprevious experimental approaches.",
        "positive": "Dislocation screening in crystals with spherical topology: Whereas disclination defects are energetically prohibitive in two-dimensional\nflat crystals, their existence is necessary in crystals with spherical\ntopology, such as viral capsids, colloidosomes or fullerenes. Such a\ngeometrical frustration gives rise to large elastic stresses, which render the\ncrystal unstable when its size is significantly larger than the typical lattice\nspacing. Depending on the compliance of the crystal with respect to stretching\nand bending deformations, these stresses are alleviated by either a local\nincrease of the intrinsic curvature in proximity of the disclinations or by the\nproliferation of excess dislocations, often organized in the form of\none-dimensional chains known as \"scars\". The associated strain field of the\nscars is such to counterbalance the one resulting from the isolated\ndisclinations. Here, we develop a continuum theory of dislocation screening in\ntwo-dimensional closed crystals with genus one. Upon modeling the flux of scars\nemanating from a given disclination as an independent scalar field, we\ndemonstrate that the elastic energy of closed two-dimensional crystals with\nvarious degrees of asphericity can be expressed as a simple quadratic function\nof the screened topological charge of the disclinations, both at zero and\nfinite temperature. This allows us to predict the optimal density of the excess\ndislocations as well as the minimal stretching energy attained by the crystal."
    },
    {
        "anchor": "Fluid Mechanical and Electrical Fluctuation Forces in Colloids: Fluctuations in fluid velocity and fluctuations in electric fields may both\ngive rise to forces acting on small particles in colloidal suspensions. Such\nforces in part determine the thermodynamic stability of the colloid. At the\nclassical statistical thermodynamic level, the fluid velocity and electric\nfield contributions to the forces are comparable in magnitude. When quantum\nfluctuation effects are taken into account, the electric fluctuation induced\nvan der Waals forces dominate those induced by purely fluid mechanical motions.\nThe physical principles are applied in detail for the case of colloidal\nparticle attraction to the walls of the suspension container and more briefly\nfor the case of forces between colloidal particles.",
        "positive": "Mechanical Properties of Viral Capsids: Viruses are known to tolerate wide ranges of pH and salt conditions and to\nwithstand internal pressures as high as 100 atmospheres. In this paper we\ninvestigate the mechanical properties of viral capsids, calling explicit\nattention to the inhomogeneity of the shells that is inherent to their discrete\nand polyhedral nature. We calculate the distribution of stress in these capsids\nand analyze their response to isotropic internal pressure (arising, for\ninstance, from genome confinement and/or osmotic activity). We compare our\nresults with appropriate generalizations of classical (i.e., continuum)\nelasticity theory. We also examine competing mechanisms for viral shell\nfailure, e.g., in-plane crack formation versus radial bursting. The biological\nconsequences of the special stabilities and stress distributions of viral\ncapsids are also discussed."
    },
    {
        "anchor": "Experimental Measurements of the Granular Density of Modes via Impact: The jamming transition is an important feature of granular materials, with\nprior work showing an excess of low frequency modes in the granular analog to\nthe density of states, the granular density of modes. In this work, we present\nan experimental method for acoustically measuring the granular density of modes\nusing a single impact event to excite vibrational modes in an experimental,\nthree dimensional, granular material. We test three different granular\nmaterials, all of which are composed of spherical beads. The first two systems\nare monodisperse collections of either 6 mm or 8 mm diameter beads. The third\nsystem is a bidisperse mixture of the previous two bead sizes. During data\ncollection, the particles are confined to a box; on top of this box, and\nresting on the granular material, is a light, rigid sheet onto which pressure\ncan be applied to the system. To excite the material, a steel impactor ball is\ndropped on top of the system. The response of the granular material to the\nimpact pulse is recorded by piezoelectric sensors buried throughout the\nmaterial, and the density of modes is computed from the spectrum of the\nvelocity autocorrelation of these sensors. Our measurements of the density of\nmodes show more low frequency modes at low pressure, consistent with previous\nexperimental and numerical results, as well as several low frequency peaks in\nthe density of modes that shift with applied pressure. Finally, we also see\nthat the density of modes falls off at a wavelength on the order of twice the\nparticle diameter, which is reminiscent of the Debye frequency.",
        "positive": "Distinguishing thixotropy from viscoelasticity: Owing to nonlinear viscoelasticity, materials often show characteristic\nfeatures that resemble those of thixotropy. This issue has been debated in the\nliterature over the past several decades, and several experimental protocols\nhave been proposed to distinguish thixotropy from viscoelasticity. In this\nwork, we assess these protocols by carrying out experiments using polymer\nsolutions, thixotropic clay dispersions, and modeling their behavior,\nrespectively, using the FENE-P constitutive equation and a viscoelastic aging\nmodel. We find that the criteria proposed in the literature, such as a step\ndown jump in the shear rate and shear startup at different waiting times\nelapsed since preshear, are inadequate to distinguish thixotropy from\nviscoelasticity. In marked contrast, we show that the application of\nstep-strain or step-stress after cessation of the preshear serves as a useful\ndiscriminant between thixotropy and viscoelasticity. In thixotropic materials,\nwe observe that the application of step strain (or step stress) after cessation\nof the preshear eventually leads to slowing down of relaxation dynamics as a\nfunction of waiting time. However, for viscoelastic materials, the relaxation\nmodulus (creep compliance) curve shifts to lower modulus (higher compliance)\nvalues as a function of waiting time until equilibrium is reached. While the\nproposed criterion offers a robust distinction between viscoelasticity and\nthixotropy for the systems studied here, further experimental investigations\nbased on other systems are needed to establish its versatility and will lead to\na greater insight into this long-standing issue in rheological categorization."
    },
    {
        "anchor": "Dynamics of a membrane coupled to an active fluid: The dynamics of a membrane coupled to an active fluid on top of a substrate\nis considered theoretically. It is assumed that the director field of the\nactive fluid has rotational symmetry in the membrane plane. This situation is\nlikely to be relevant for in vitro reconstructed actomyosin-membrane system.\nDifferent from a membrane coupled to a polar active fluid, this model predicts\nthat only when the viscosity of the fluid above the membrane is sufficiently\nlarge, a contractile active fluid is able to slow down the relaxation of the\nmembrane for perturbations with wavelength comparable to the thickness of the\nactive fluid. Hence our model predicts a finite-wavelength instability in the\nlimit of strong contractility, which is different from a membrane coupled to a\npolar active fluid. On the other hand, a membrane coupled to an extensile\nactive fluid is always unstable against long wavelength perturbations due to\nsplay induced flows.",
        "positive": "Microscopic theory of glassy dynamics and glass transition for molecular\n  crystals: We derive a microscopic equation of motion for the dynamical orientational\ncorrelators of molecular crystals. Our approach is based upon mode coupling\ntheory. Compared to liquids we find four main differences: (i) the memory\nkernel contains Umklapp processes, (ii) besides the static two-molecule\norientational correlators one also needs the static one-molecule orientational\ndensity as an input, where the latter is nontrivial, (iii) the static\norientational current density correlator does contribute an anisotropic,\ninertia-independent part to the memory kernel, (iv) if the molecules are\nassumed to be fixed on a rigid lattice, the tensorial orientational correlators\nand the memory kernel have vanishing l,l'=0 components. The resulting mode\ncoupling equations are solved for hard ellipsoids of revolution on a rigid\nsc-lattice. Using the static orientational correlators from Percus-Yevick\ntheory we find an ideal glass transition generated due to precursors of\norientational order which depend on X and p, the aspect ratio and packing\nfraction of the ellipsoids. The glass formation of oblate ellipsoids is\nenhanced compared to that for prolate ones. For oblate ellipsoids with X <~ 0.7\nand prolate ellipsoids with X >~ 4, the critical diagonal nonergodicity\nparameters in reciprocal space exhibit more or less sharp maxima at the zone\ncenter with very small values elsewhere, while for prolate ellipsoids with 2 <~\nX <~ 2.5 we have maxima at the zone edge. The off-diagonal nonergodicity\nparameters are not restricted to positive values and show similar behavior. For\n0.7 <~ X <~ 2, no glass transition is found. In the glass phase, the\nnonergodicity parameters show a pronounced q-dependence."
    },
    {
        "anchor": "Fluid Flows Created by Swimming Bacteria Drive Self-Organization in\n  Confined Suspensions: Concentrated suspensions of swimming microorganisms and other forms of active\nmatter are known to display complex, self-organized spatio-temporal patterns on\nscales large compared to those of the individual motile units. Despite\nintensive experimental and theoretical study, it has remained unclear the\nextent to which the hydrodynamic flows generated by swimming cells, rather than\npurely steric interactions between them, drive the self-organization. Here we\nutilize the recent discovery of a spiral-vortex state in confined suspensions\nof \\textit{B. subtilis} to study this issue in detail. Those experiments showed\nthat if the radius of confinement in a thin cylindrical chamber is below a\ncritical value the suspension will spontaneously form a steady single-vortex\nstate encircled by a counter-rotating cell boundary layer, with spiral cell\norientation within the vortex. Left unclear, however, was the flagellar\norientation, and hence the cell swimming direction, within the spiral vortex.\nHere, using a fast simulation method that captures oriented cell-cell and\ncell-fluid interactions in a minimal model of discrete-particle systems, we\npredict the striking, counterintuitive result that in the presence of\ncollectively-generated fluid motion the cells within the spiral vortex actually\nswim upstream against those flows. This is then confirmed by new experiments\nreported here, which include measurements of flagella bundle orientation and\ncell tracking in the self-organized state. These results highlight the complex\ninterplay between cell orientation and hydrodynamic flows in concentrated\nsuspensions of microorganisms.",
        "positive": "Thermodynamic driving forces in contact electrification between\n  polymeric materials: Contact electrification, or contact charging, refers to the process of static\ncharge accumulation after rubbing, or even simple touching, of two materials.\nDespite its relevance in static electricity, various natural phenomena, and\nnumerous technologies, contact charging remains poorly understood. For\ninsulating materials, even the species of charge carrier may be unknown, and\nthe direction of charge-transfer lacks firm molecular-level explanation. We use\nall-atom molecular dynamics simulations to investigate whether thermodynamics\ncan explain contact charging between insulating polymers. Building on prior\nwork implicating water-ions (e.g., hydronium and hydroxide) as potential charge\ncarriers, we predict preferred directions of charge-transfer between polymer\nsurfaces according to the free energy of water-ions within water droplets on\nsuch surfaces. Broad agreement between our predictions and experimental\ntriboelectric series indicate that thermodynamically driven ion-transfer likely\ninfluences contact charging of polymers. Importantly, simulation analyses\nreveal how specific interactions of water and water-ions proximate to the\npolymer-water interface explains observed trends. This study establishes\nrelevance of thermodynamic driving forces in contact charging of insulators\nwith new evidence informed by molecular-level interactions. These insights have\ndirect implications for future mechanistic studies and applications of contact\ncharging involving polymeric materials."
    },
    {
        "anchor": "Interactions and Correlations of Particulate Inclusions in a Columnar\n  Phase: We calculate the elastic field mediated interaction between macroscopic\nparticles in a columnar hexagonal phase. The interaction is found to be\nlong-ranged and non-central, with both attractive and repulsive parts. We show\nhow the interaction modifies the particle correlations and the column\nfluctuations. We also calculate the interaction of particles with the\ntopological defects of the columnar phase. The particle-defect interaction\nreduces the mobility of the defects.",
        "positive": "Localised bulging of an inflated rubber tube with fixed ends: When a rubber tube with free ends is inflated under volume control, the\npressure will first reach a maximum and then decrease monotonically to approach\na constant asymptote. The pressure maximum corresponds to the initiation of a\nlocalised bulge and is predicted by a bifurcation condition, whereas the\nasymptote is the Maxwell pressure corresponding to a \"two-phase\" propagation\nstate. In contrast, when the tube is first pre-stretched and then has its ends\nfixed during subsequent inflation, the pressure versus bulge amplitude has both\na maximum and a minimum, and the behaviour on the right ascending branch has\npreviously not been fully understood. We show that for all values of\npre-stretch and tube length, the ascending branches all converge to a single\ncurve that is only dependent on the ratio of tube thickness to the outer\nradius. This curve represents the Maxwell state to be approached in each case\n(if Euler buckling or axisymmetric wrinkling does not occur first), but this\nstate is pressure-dependent in contrast with the free-ends case. We also\ndemonstrate experimentally that localized bulging cannot occur when the\npre-stretch is sufficiently large and investigate what strain-energy functions\ncan predict this observed phenomenon."
    },
    {
        "anchor": "Fully reversible transition from Wenzel to Cassie-Baxter states on\n  corrugated superhydrophobic surfaces: Liquid drops on textured surfaces show different dynamical behaviors\ndepending on their wetting states. They are extremely mobile when they are\nsupported by composite solid-liquid-air interfaces (Cassie-Baxter state) and\nimmobile when they fully wet the textured surfaces (Wenzel state). By\nreversibly switching between these two states, it will be possible to achieve\nlarge control over the fluid dynamics. Unfortunately, these wetting transitions\nare usually prevented by surface energy barriers. We demonstrate here a new and\nsimple design paradigm, consisting of parallel grooves of appropriate aspect\nratio, that allows for a controlled, barrierless, and reversible switching of\nthe wetting states upon the application of electrowetting. We report a direct\nobservation of the barrierless dynamical pathway for the reversible transitions\nbetween the Wenzel (collapsed) and the Cassie-Baxter (suspended) states and\npresent a theory that accounts for these transitions, including detailed\nlattice-Boltzmann simulations.",
        "positive": "Stationary finger solutions in the Hele-Shaw cell: We solve numerically the nonlinear differential equation for the Hele-Shaw,\nSaffman-Taylor problem derived in the preceding work. Stationary solutions with\nno free phenomenological parameters are found to fit the measured patterns. The\ncalculated finger half-widths as a function of the physical parameters of the\ncell, compare satisfactorily with experiment."
    },
    {
        "anchor": "On Static and Dynamic Heterogeneities in Water: We analyze differences in dynamics and in properties of the sampled potential\nenergy landscape between different equilibrium trajectories, for a system of\nrigid water molecules interacting with a two body potential. On entering in the\nsupercooled region, differences between different realizations enhance and\nsurvive even when particles have diffused several time their average distance.\nWe observe a strong correlation between the mean square displacement of the\nindividual trajectories and the average energy of the sampled landscape.",
        "positive": "Particle Monte Carlo simulation of string-like colloidal assembly in 2\n  dimensions: We simulate structural phase behavior of polymer-grafted colloidal particles\nby molecular Monte Carlo technique. Interparticle potential, which has a finite\nrepulsive square-step outside a rigid core of the colloid, was previously\nconfirmed via numerical self-consistent field calculation. This model potential\nis purely repulsive. We simulate these model colloids in the canonical ensemble\nin 2 dimensions and find that these particles containing no interparticle\nattraction self-assemble and align in a string-like assembly, at low\ntemperature and high density. This string-like colloidal assembly is related to\npercolation phenomena. Analyzing the cluster size distribution and the average\nstring length, we build phase diagrams and discover that the average string\nlength diverges around the region where the melting transition line and the\npercolation transition line cross. This result is similar to Ising spin\nsystems, in which the percolation transition line and the order-disorder line\nmeet at a critical point."
    },
    {
        "anchor": "Supersonic dislocations observed in a plasma crystal: Experimental results on the dislocation dynamics in a two-dimensional plasma\ncrystal are presented. Edge dislocations were created in pairs in lattice\nlocations where the internal shear stress exceeded a threshold and then moved\napart in the glide plane at a speed higher than the sound speed of shear waves,\n$C_T$. The experimental system, a plasma crystal, allowed observation of this\nprocess at an atomistic (kinetic) level. The early stage of this process is\nidentified as a stacking fault. At a later stage, supersonically moving\ndislocations generated shear-wave Mach cones.",
        "positive": "Novel crystal phase in suspensions of hard ellipsoids: We present a computer simulation study on the crystalline phases of hard\nellipsoids of revolution. For aspect ratios greater than or equal to 3 the\npreviously suggested stretched-fcc phase [D. Frenkel and B. M. Mulder, Mol.\nPhys. 55, 1171 (1985)] is replaced by a novel crystalline phase. Its unit cell\ncontains two ellipsoids with unequal orientations. The lattice is simple\nmonoclinic. The angle of inclination of the lattice, beta, is a very soft\ndegree of freedom, while the two right angles are stiff. For one particular\nvalue of beta, the close-packed version of this crystal is a specimen of the\nfamily of superdense packings recently reported [Donev et al., Phys. Rev. Lett.\n92, 255506 (2004)]. These results are relevant for studies of nucleation and\nglassy dynamics of colloidal suspensions of ellipsoids."
    },
    {
        "anchor": "Microcanonical Analyses of Peptide Aggregation Processes: We propose the use of microcanonical analyses for numerical studies of\npeptide aggregation transitions. Performing multicanonical Monte Carlo\nsimulations of a simple hydrophobic-polar continuum model for interacting\nheteropolymers of finite length, we find that the microcanonical entropy\nbehaves convex in the transition region, leading to a negative microcanonical\nspecific heat. As this effect is also seen in first-order-like transitions of\nother finite systems, our results provide clear evidence for recent hints that\nthe characterisation of phase separation in first-order-like transitions of\nfinite systems profits from this microcanonical view.",
        "positive": "Bleaching and stimulated recovery of dyes and of photo-cantilevers: We examine how intense optical beams can penetrate deeply into highly\nabsorbing media by a non-linear, photo-bleaching process. The role of\nstimulated recovery to the dye ground state can be important and is delineated.\nThis analysis of non-linear absorption processes is applicable in general to\nsituations where chromophores are irradiated, for instance in biology. We\nexamine the implications for the bending of cantilevers made of heavily\ndye-loaded nematic photo-solids, that is nematic glasses and elastomers that\nhave large mechanical reactions to light. In particular we describe the bending\nof cantilevers sufficiently absorbing that they would not bend if Beer's Law\nwere applicable. We quantify the role of optically-generated heat in\ndetermining the mechanical response and conclude that in general it is minor in\nimportance compared with optical effects."
    },
    {
        "anchor": "Rheological Study of Transient Networks with Junctions of Limited\n  Multiplicity: Viscoelastic and thermodynamic properties of transient gels comprised of\ntelechelic polymers are theoretically studied. We extend classical theories of\ntransient networks so that correlations among polymer chains through the\nnetwork junctions are taken into account. This extension enables us to\ninvestigate how rheological quantities, such as viscosity and elastic modulus,\nare affected by the association equilibrium conditions, and how these\nquantities are related to the aggregation number of junctions. We present a\ntheoretical model of transient networks with junctions comprised of variable\nnumber of hydrophobic groups on the chain ends. Elastically effective chains\nare defined as the chains whose both ends are associated with end groups on\nother chains. It is shown that the dynamic shear moduli are well described in\nterms of the Maxwell model characterized by a single relaxation time and the\nhigh-frequency plateau modulus as in the classical theories, but the reduced\ndynamic shear moduli depend on the polymer concentration and temperature\nthrough the reduced concentration c given as a combination of the association\nconstant and the volume fraction of end groups. The plateau modulus and the\nzero-shear viscosity rise nonlinearly with increasing c when c is small, but\nthey are proportional to c for higher c. The relaxation time also increases as\nc increases due to the presence of pairwise junctions at small c.",
        "positive": "Molecular dynamics simulations of single-component bottle-brush polymers\n  with a flexible backbone under poor solvent conditions: Conformations of a single-component bottle-brush polymer with a fully\nflexible backbone under poor solvent conditions are studied by\nmolecular-dynamics simulations, using a coarse-grained bead-spring model with\nside chains of up to N=40 effective monomers. By variation of the solvent\nquality and the grafting density $\\sigma$ with which side chains are grafted\nonto the flexible backbone, we study for backbone lengths of up to $N_b=100$\nthe crossover from the brush/coil regime to the dense collapsed state. At lower\ntemperatures, where collapsed chains with a constant monomer density are\nobserved, the choice of the above parameters does not play any role and it is\nthe total number of monomers that defines the dimensions of the chains.\nFurthermore, bottle-brush polymers with longer side chains possess higher\nspherical symmetry compared to chains with lower side-chain lengths in contrast\nto what one may intuitively expect, as the stretching of the side chains is\nless important than the increase of their length. At higher temperatures,\nalways below the Theta ($\\Theta$) temperature, coil-like configurations,\nsimilar to a single polymer chain, or brush-like configurations, similar to a\nhomogeneous cylindrical bottle-brush polymer with a rigid backbone, are\nobserved, depending on the choice of the particular parameters $N$ and\n$\\sigma$. In the crossover regime between the collapsed state (globule) and the\ncoil/brush regime the acylindricity increases, whereas for temperatures outside\nof this range, bottle-brush polymers maintain a highly cylindrical symmetry in\nall configurational states."
    },
    {
        "anchor": "Structural trends in clusters of quadrupolar spheres: The influence of quadrupolar interactions on the structure of small clusters\nis investigated by adding a point quadrupole of variable strength to the\nLennard-Jones potential. Competition arises between sheet-like arrangements of\nthe particles, favoured by the quadrupoles, and compact structures, favoured by\nthe isotropic Lennard-Jones attraction. Putative global potential energy minima\nare obtained for clusters of up to 25 particles using the basin-hopping\nalgorithm. A number of structural motifs and growth sequences emerge, including\nstar-like structures, tubes, shells and sheets. The results are discussed in\nthe context of colloidal self-assembly.",
        "positive": "Entrapping a polymer chain in a light well under a good solvent\n  condition: During the last decade, the laser trapping technique has been actively\napplied to elucidate the property of macromolecules, DNA, RNA, cytoskeleton\nfibres, etc. Due to the inherent difficulty in the direct trapping of single\nmolecules at approximately 300 K, most of the current studies on laser trapping\nutilize the experimental technique to grasp microbeads that are attached to a\nsingle macromolecule, instead of using direct trapping. A few studies have\ndemonstrated the applicability of laser trapping for highly packed compact DNA\nunder a `poor' solvent condition without any beads. The present study achieves\nlaser trapping on a single DNA molecule under a `good' solvent condition\nwithout any microbeads. The time-dependent change of the conformation\naccompanied by ON/OFF laser irradiation was measured and analysed in terms of\nthe entrapment and release of a coiled polymer around a micrometer-sized\npotential."
    },
    {
        "anchor": "A constitutive law for dense granular flows: A continuum description of granular flows would be of considerable help in\npredicting natural geophysical hazards or in designing industrial processes.\nHowever, the constitutive equations for dry granular flows, which govern how\nthe material moves under shear, are still a matter of debate. One difficulty is\nthat grains can behave like a solid (in a sand pile), a liquid (when poured\nfrom a silo) or a gas (when strongly agitated). For the two extreme regimes,\nconstitutive equations have been proposed based on kinetic theory for\ncollisional rapid flows, and soil mechanics for slow plastic flows. However,\nthe intermediate dense regime, where the granular material flows like a liquid,\nstill lacks a unified view and has motivated many studies over the past decade.\nThe main characteristics of granular liquids are: a yield criterion (a critical\nshear stress below which flow is not possible) and a complex dependence on\nshear rate when flowing. In this sense, granular matter shares similarities\nwith classical visco-plastic fluids such as Bingham fluids. Here we propose a\nnew constitutive relation for dense granular flows, inspired by this analogy\nand recent numerical and experimental work. We then test our three-dimensional\n(3D) model through experiments on granular flows on a pile between rough\nsidewalls, in which a complex 3D flow pattern develops. We show that, without\nany fitting parameter, the model gives quantitative predictions for the flow\nshape and velocity profiles. Our results support the idea that a simple\nvisco-plastic approach can quantitatively capture granular flow properties, and\ncould serve as a basic tool for modelling more complex flows in geophysical or\nindustrial applications.",
        "positive": "Beyond linear elasticity: Jammed solids at finite shear strain and rate: The shear response of soft solids can be modeled with linear elasticity,\nprovided the forcing is slow and weak. Both of these approximations must break\ndown when the material loses rigidity, such as in foams and emulsions at their\n(un)jamming point -- suggesting that the window of linear elastic response near\njamming is exceedingly narrow. Yet precisely when and how this breakdown occurs\nremains unclear. To answer these questions, we perform computer simulations of\nstress relaxation and shear startup experiments in athermal soft sphere\npackings, the canonical model for jamming. By systematically varying the strain\namplitude, strain rate, distance to jamming, and system size, we identify\ncharacteristic strain and time scales that quantify how and when the window of\nlinear elasticity closes, and relate these scales to changes in the microscopic\ncontact network. Our findings indicate that the mechanical response of jammed\nsolids are generically nonlinear and rate-dependent on experimentally\naccessible strain and time scales."
    },
    {
        "anchor": "Thermal fluctuations and anomalous elasticity of homogeneous nematic\n  elastomers: We present a unified formulation of a rotationally invariant nonlinear\nelasticity for a variety of spontaneously anisotropic phases, and use it to\nstudy thermal fluctuations in nematic elastomers and spontaneously anisotropic\ngels. We find that in a thermodynamic limit homogeneous nematic elastomers are\nuniversally incompressible, are characterized by a universal ratio of shear\nmoduli, and exhibit an anomalous elasticity controlled by a nontrivial low\ntemperature fixed point perturbative in D=3-epsilon dimensions. In three\ndimensions, we make predictions that are asymptotically exact.",
        "positive": "Stress chain analysis of soil particles in slope via persistent homology: The relationship between the macroscopic response of the slope and the\nmacrostructure of the force chain network under the action of the metal plate\nwas studied by the particle discrete element method and the persistent\nhomology. The particle accumulation model was used to simulate the instability\nprocess of slope under the continuous downward action of metal plate by the\nparticle discrete element method. The macroscopic responses such as the total\nvelocity vector of the two-dimensional slope deposit, the angle of the slip\ncracking surface when the slope is unstable, and the average velocity in the\ny-direction of the slope were studied. Then, the normal force chain undirected\nnetwork model of the natural accumulation of slope stacking particles was\nconstructed. Finally, the topological characteristics of the particle contact\nforce chain network of the slope top were analyzed by the persistent homology\nmethod to obtain the barcode. Finally, the relationship between the instability\nevolution and the characteristics of persistent homology is established. This\nresearch provides a new method for the study of slope instability topology\nidentification. Thus, the instability destruction of slope can be predicted\neffectively."
    },
    {
        "anchor": "Strong Effect of Weak Charging in Suspensions of Anisotropic Colloids: Suspensions of hard colloidal particles frequently serve as model systems in\nstudies on fundamental aspects of phase transitions. But often colloidal\nparticles that are considered as ``hard'' are in fact weakly charged. If the\ncolloids are spherical, weak charging has a only a weak effect on the\nstructural properties of the suspension, which can be easily corrected for.\nHowever, this does not hold for anisotropic particles.\n  We introduce a model for the interaction potential between charged ellipsoids\nof revolution (spheroids) based on the Derjaguin approximation of\nDebye--H\\\"uckel Theory and present a computer simulation study on aspects of\nthe system's structural properties and phase behaviour. In line with previous\nexperimental observations, we find that even a weak surface charge has a strong\nimpact on the correlation functions. A likewise strong impact is seen on the\nphase behaviour, in particular, we find stable cubatic order in suspensions of\noblate ellipsoids.",
        "positive": "Slip vs viscoelasticity in dewetting thin films: Ultrathin polymer films on non-wettable substrates display dynamic features\nwhich have been attributed to either viscoelastic or slip effects. Here we show\nthat in the weak and strong slip regime effects of viscoelastic relaxation are\neither absent or not distinguishable from slip effects. Strong-slip modifies\nthe fastest unstable mode in a rupturing thin film, which questions the\nstandard approach to reconstruct the effective interface potential from\ndewetting experiments."
    },
    {
        "anchor": "Surfactant films in lyotropic lamellar (and related) phases:\n  Fluctuations and interactions: The analogy between soap films thinning under border capillary suction and\nlamellar stacks of surfactant bilayers dehydrated by osmotic stress is\nexplored, in particular in the highly dehydrated limit where the soap film\nbecomes a Newton black film. The nature of short-range repulsive interactions\nbetween surfactant-covered interfaces and acting across water channels in both\ncases will be discussed.",
        "positive": "The Structure and Thermodynamic Stability of Reverse Micelles in Dry\n  AOT/Alkane Mixtures: Monte Carlo simulation studies of reverse micelles of an anionic surfactant,\nsodium AOT, in a non-polar solvent provide strong evidence that, in the absence\nof water, these clusters are charge ordered polyhedral shells. The stabilizing\nenergy of these clusters is so large that the entropy of mixing is, in\ncomparison, inconsequential and we predict that, if all waters of hydration\ncould be removed (something not yet accomplished for the sodium salt) then AOT\nwould be insoluble in nonpolar solvents."
    },
    {
        "anchor": "Effect of premelting on conductivity of DNA-lipid films: We have measured temperature dependent (between 20 and 80 C) electrical\nconductivity and molecular structure (Raman spectroscopy) of DNA-lipid cast\nfilm. Our findings show that the conductivity is strongly influenced by\npremelting effects in the molecular structure starting near physiological\ntemperatures (~40 C), prior to the global DNA denaturation.",
        "positive": "Lagrangian Mechanics of Active Systems: We present a multi-scale modeling and simulation framework for low-Reynolds\nnumber hydrodynamics of shape-changing immersed objects, e.g., biological\nmicroswimmers and active surfaces. The key idea is to consider principal shape\nchanges as generalized coordinates, and define conjugate generalized\nhydrodynamic friction forces. Conveniently, the corresponding generalized\nfriction coefficients can be pre-computed and subsequently re-used to solve\ndynamic equations of motion fast. This framework extends Lagrangian mechanics\nof dissipative systems to active surfaces and active microswimmers, whose shape\ndynamics is driven by internal forces. As an application case, we predict\nin-phase and anti-phase synchronization in pairs of cilia for an experimentally\nmeasured cilia beat pattern."
    },
    {
        "anchor": "Efficient Machine Learning Force Field for Large-Scale Molecular\n  Simulations of Organic Systems: To address the computational challenges of ab initio molecular dynamics and\nthe accuracy limitations of empirical force fields, the introduction of machine\nlearning force fields has proven effective in various systems including metals\nand inorganic materials. However, in large-scale organic systems, the\napplication of machine learning force fields is often hindered by impediments\nsuch as the complexity of long-range intermolecular interactions and molecular\nconformations, as well as the instability in long-time molecular simulations.\nTherefore, we propose a universal multiscale higher-order equivariant model\ncombined with active learning techniques, efficiently capturing the complex\nlong-range intermolecular interactions and molecular conformations. Compared to\nexisting equivariant models, our model achieves the highest predictive\naccuracy, and magnitude-level improvements in computational speed and memory\nefficiency. In addition, a bond length stretching method is designed to improve\nthe stability of long-time molecular simulations. Utilizing only 901 samples\nfrom a dataset with 120 atoms, our model successfully extends high precision to\nsystems with hundreds of thousands of atoms. These achievements guarantee high\npredictive accuracy, fast simulation speed, minimal memory consumption, and\nrobust simulation stability, satisfying the requirements for high-precision and\nlong-time molecular simulations in large-scale organic systems.",
        "positive": "Phase transitions and membrane stiffness in a class of asymmetric\n  heterogeneous fluid membranes: We propose a minimal model for miscibility phase transitions (MPTs) in a\nclass of asymmetric two-component heterogeneous fluid membranes at equilibrium\nthat generically display both first and second order MPTs, controlled by the\ninterplay of asymmetry and heterogeneity. In the vicinity of the MPTs, the\nmembrane fluctuations are generally enhanced. However, the degree of\nenhancement is found to depend sensitively on the asymmetry-heterogeneity\ncoupling. We argue that experimental measurements of the membrane fluctuations\nat the MPTs should provide physical information about the forms of the\nasymmetry-heterogeneity couplings."
    },
    {
        "anchor": "Field-mediated interactions of passive and conformation-active\n  particles: multibody and retardation effects: Particles in soft matter often interact through the deformation field they\ncreate, as in the \"cheerios\" effect or the curvature-mediated interactions of\nmembrane proteins. Using a simple model for field-mediated interactions between\npassive particles, or active particles that switch conformation randomly or\nsynchronously, we derive generic results concerning multibody interactions,\nactivity driven patterns, and retardation effects.",
        "positive": "Disorder-induced vibrational anomalies from crystalline to amorphous\n  solids: The origin of boson peak -- an excess of density of states over Debye's model\nin glassy solids -- is still under intense debate, among which some theories\nand experiments suggest that boson peak is related to van-Hove singularity.\nHere we show that boson peak and van-Hove singularity are well separated\nidentities, by measuring the vibrational density of states of a two-dimensional\ngranular system, where packings are tuned gradually from a crystalline, to\npolycrystals, and to an amorphous material. We observe a coexistence of well\nseparated boson peak and van-Hove singularities in polycrystals, in which the\nvan-Hove singularities gradually shift to higher frequency values while\nbroadening their shapes and eventually disappear completely when the structural\ndisorder $\\eta$ becomes sufficiently high. By analyzing firstly the strongly\ndisordered system ($\\eta=1$) and the disordered granular crystals ($\\eta=0$),\nand then systems of intermediate disorder with $\\eta$ in between, we find that\nboson peak is associated with spatially uncorrelated random flucutations of\nshear modulus $\\delta G/\\langle G \\rangle$ whereas the smearing of van-Hove\nsingularities is associated with spatially correlated fluctuations of shear\nmodulus $\\delta G/\\langle G \\rangle$."
    },
    {
        "anchor": "Dipole alignment of water molecules flowing through a carbon nanotube: The fast flow rate of water through nanochannels has promising applications\nin desalination, energy conversion, and nanomedicine. We have used molecular\ndynamics simulations to show that the water molecules passing through a wide\nsingle-walled carbon nanotube (CNT) cavity get aligned by flow to have a net\ndipole moment along the flow direction. With increasing flow velocity, the net\ndipole moment first increases and eventually saturates to a constant value.\nThis behavior is similar to the Langevin theory of paraelectricity with the\nflow velocity acting as an effective aligning field. We show conclusively that\nthe microscopic origin of this behavior is the preferential entry of water\nmolecules with their dipole vectors pointing inward along the CNT axis.",
        "positive": "Influence of Homeotropic Anchoring Walls upon Nematic and Smectic Phases: McMillan liquid crystal model sandwiched between strong homeotropic anchoring\nwalls is studied. Phase transitions between isotropic, nematic, and smectic A\nphases are investigated for wide ranges of an interaction parameter and of the\nsystem thickness. It is confirmed that the anchoring walls induce an increase\nin transition temperatures, dissappearance of phase transitions, and an\nappearance of non-spontaneous nematic phase. The similarity between influence\nof anchoring walls and that of external fields is discussed."
    },
    {
        "anchor": "Phase Diagram of Diblock Copolymer Melt in Dimension d=5: Using the self-consistent field theory (SCFT) in spherical unit cells of\nvarious dimensionalities, D, a phase diagram of a diblock, A-b-B, is calculated\nin 5 dimensional space, d = 5. This is an extension of a previous work for d =\n4. The phase diagram is parameterized by the chain composition, f, and\nincompatibility between A and B , quantified by the product \\c{hi} N. We\npredict 5 stable nanophases: layers, cylinders, 3 D spherical cells, 4D\nspherical cells, and 5D spherical cells. In the strong segregation limit, that\nis for large \\c{hi}N, the order-order transition compositions are determined by\nthe strong segregation theory (SST) in its simplest form. While the predictions\nof the SST theory are close to the corresponding SCFT extrapolations for d=4,\nthe extrapolations for d=5 significantly differ from them. We find that the S5\nnanophase is stable in a narrow strip between the ordered S4 nanophase and the\ndisordered phase. The calculated order-disorder transition lines depend weakly\non d, as expected.",
        "positive": "Random Isotropic Structures and Possible Glass Transitions in Diblock\n  Copolymer Melts: We study the microstructural glass transitions in diblock-copolymer melts\nusing a thermodynamic replica approach. Our approach performs an expansion in\nterms of the natural smallness parameter -- the inverse of the scaled degree of\npolymerization, which allows us to systematically study the approach to\nmean-field behavior as the degree of polymerization increases. We find that in\nthe limit of infinite long polymer chains, both the onset of glassiness and the\nvitrification transition (Kauzmann temperature) collapse to the mean-field\nspinodal, suggesting that the spinodal can be regarded as the mean-field\nsignature for glass transitions in this class of systems. We also study the\norder-disorder transitions (ODT) within the same theoretical framework; in\nparticular, we include the leading-order fluctuation corrections due to the\ncubic interaction in the coarse-grained Hamiltonian, which has been ignored in\nprevious works on the ODT in block copolymers. We find that the cubic term\nstabilizes both the ordered (body-centered-cubic) phase and the glassy state\nrelative to the disordered phase. While in melts of symmetric copolymers the\nglass transition always occurs after the order-disorder transition (below the\nODT temperature), for asymmetric copolymers, it is possible that the glass\ntransition precedes the ordering transition."
    },
    {
        "anchor": "Hard-body models of bulk liquid crystals: Hard models for particle interactions have played a crucial role in the\nunderstanding of the structure of condensed matter. In particular, they help to\nexplain the formation of oriented phases in liquids made of anisotropic\nmolecules or colloidal particles, and continue to be of great interest in the\nformulation of theories for liquids in bulk, near interfaces and in biophysical\nenvironments. Hard models of anisotropic particles give rise to complex phase\ndiagrams, including uniaxial and biaxial nematic phases, discotic phases, and\nspatially ordered phases such as smectic, columnar or crystal. Also, their\nmixtures exhibit additional interesting behaviours where demixing competes with\norientational order. Here we review the different models of hard particles used\nin the theory of bulk anisotropic liquids, leaving aside interfacial\nproperties, and discuss the associated theoretical approaches and computer\nsimulations, focusing on applications in equilibrium situations. The latter\ninclude one-component bulk fluids, mixtures and polydisperse fluids, both in\ntwo and three dimensions, and emphasis is put on liquid-crystal phase\ntransitions and complex phase behaviour in general.",
        "positive": "Structure Formation due to Antagonistic Salts: Antagonistic salts are composed of hydrophilic and hydrophobic ions. In a\nmixture solvent (water-oil) such ion pairs are preferentially attracted to\nwater or oil, giving rise to a coupling between the charge density and the\ncomposition. First, they form a large electric double layer at a water-oil\ninterface, reducing the surface tension and producing mesophases. Here, the\ncations and anions are loosely bound by the Coulomb attraction across the\ninterface on the scale of the Debye screening length. Second, on solid\nsurfaces, hydrophilic (hydrophobic) ions are trapped in a water-rich (oil-rich)\nadsorption layer, while those of the other species are expelled from the layer.\nThis yields a solvation mechanism of local charge separation near a solid. In\nparticular, near the solvent criticality, disturbances around solid surfaces\ncan become oscillatory in space. In mesophases, we calculate periodic\nstructures, which resemble those in experiments."
    },
    {
        "anchor": "Phase and vacancy behaviour of hard \"slanted\" cubes: We use computer simulations to study the phase behaviour for hard, right\nrhombic prisms as a function of the angle of their rhombic face (the \"slant\"\nangle). More specifically, using a combination of event-driven molecular\ndynamics simulations, Monte Carlo simulations, and free-energy calculations, we\ndetermine and characterize the equilibrium phases formed by these particles for\nvarious slant angles and densities. Surprisingly, we find that the equilibrium\ncrystal structure for a large range of slant angles and densities is the simple\ncubic crystal - despite the fact that the particles do not have cubic symmetry.\nMoreover, we find that the equilibrium vacancy concentration in this simple\ncubic phase is extremely high and depends only on the packing fraction, and not\nthe particle shape. At higher densities, a rhombic crystal appears as the\nequilibrium phase. We summarize the phase behaviour of this system by drawing a\nphase diagram in the slant angle - packing fraction plane.",
        "positive": "Intradomain phase transitions in flexible block copolymers with\n  self-aligning segments: We study a model of flexible block copolymers (BCPs) in which there is an\nenlthalpic preference for local alignment, among like-block segments. We\ndescribe a generalization of the self-consistent field theory (SCFT) of\nflexible BCPs to include inter-segment orientational interactions via a\nLandau-DeGennes free energy associated with a polar or nematic order parameter\nfor segments of one component of a diblock copolymer. We study the equilibrium\nstates of this model numerically, using a pseudo-spectral approach to solve for\nchain conformation statistics in the presence of a self-consistent torque\ngenerated by inter-segment alignment forces. Applying this theory to the\nstructure of lamellar domains composed of symmetric diblocks possessing a\nsingle block of \"self-aligning\", polar segments, we show the emergence of\nspatially complex segment order parameters (segment director fields) within a\ngiven lamellar domain. Because BCP phase separation gives rise to spatially\ninhomogeneous orientation order of segments even in the absence of explicit\nintra-segment aligning forces, the director fields of BCPs, as well as\nthermodynamics of lamellar domain formation, exhibit a highly non-linear\ndependence on both the inter-block segregation ($\\chi N$) and the enthalpy of\nalignment ($\\varepsilon$). Specifically, we predict the stability of new phases\nof lamellar order in which distinct regions of alignment coexist within a\nsingle mesodomain, and which spontaneously break the symmetry of the lamella\npattern of composition in the melt via in-plane tilt of the director in the\ncenters of the like-composition domains. We show further that, in analogy to a\nFreedericksz transition in confined nematics, that the elastic costs to\nreorient segments within the domain, as described by Frank elasticity, increase\nthe threshold value $\\varepsilon$ needed to induce this intra-domain phase\ntransition."
    },
    {
        "anchor": "Elastic theory of unconstrained non-Euclidean plates: Non-Euclidean plates are a subset of the class of elastic bodies having no\nstress-free configuration. Such bodies exhibit residual stress when relaxed\nfrom all external constraints, and may assume complicated equilibrium shapes\neven in the absence of external forces. In this work we present a mathematical\nframework for such bodies in terms of a covariant theory of linear elasticity,\nvalid for large displacements. We propose the concept of non-Euclidean plates\nto approximate many naturally formed thin elastic structures. We derive a thin\nplate theory, which is a generalization of existing linear plate theories,\nvalid for large displacements but small strains, and arbitrary intrinsic\ngeometry. We study a particular example of a hemispherical plate. We show the\noccurrence of a spontaneous buckling transition from a stretching dominated\nconfiguration to bending dominated configurations, under variation of the plate\nthickness.",
        "positive": "Traveling fronts in active-passive particle mixtures: The emergent dynamics in phase-separated mixtures of isometric active and\npassive Brownian particles is studied numerically in two dimensions. A novel\nsteady-state of well-defined traveling fronts is observed, where the interface\nbetween the dense and the dilute phase propagates and the bulk of both phases\nis (nearly) at rest. Two kind of interfaces, advancing and receding, are formed\nby spontaneous symmetry breaking, induced by an instability of a planar\ninterface due to the formation of localized vortices. The propagation arises\ndue to flux imbalance at the interface, strongly resembling traveling fronts in\nreaction-diffusion systems. Above a threshold, the interface velocity decreases\nlinearly with increasing fraction of active particles."
    },
    {
        "anchor": "A minimal G$\\bar{\\textrm{o}}$-model for rebuilding whole genome\n  structures from haploid single-cell Hi-C data: We present a minimal computational model, which allows very fast, on-the-fly\nconstruction of three dimensional haploid interphase genomes from single cell\nHi-C contact maps using the HOOMD-blue molecular dynamics package on graphics\nprocessing units. Chromosomes are represented by a string of connected beads,\neach of which corresponds to 100,000 base pairs, and contacts are mediated via\na structure-based harmonic potential. We suggest and test two minimization\nprotocols which consistently fold into conformationally similar low energy\nstates. The latter are similar to previously published structures but are\ncalculated in a fraction of the time. We find evidence that mere fulfillment of\ncontact maps is insufficient to create experimentally relevant structures.\nParticularly, an excluded volume term is required in our model to induce the\nformation of chromosome territories. We also observe empirically that contact\nmaps do not capture the chirality of the underlying structures. Depending on\nstarting configurations and protocol details, one of two mirror images emerges.\nFinally, we analyze the occurrence of knots in a particular chromosome. The\nsame knot appears in (almost) all structures irrespective of minimization\nprotocols or even details of underlying potentials providing further evidence\nfor the existence of knots in interphase chromatin.",
        "positive": "Dynamic Approach to Weak First Order Phase Transitions: A short-time dynamic approach to weak first order phase transitions is\nproposed. Taking the 2-dimensional Potts models as examples, from short-time\nbehaviour of non-equilibrium relaxational processes starting from high\ntemperature and zero temperature states,x pseudo critical points K^{*} and\nK^{**} are determined. A clear difference of the values for K^{*} and K^{**}\ndistinguishes a weak first order transition from a second order one. At the\npseudo critical points, pseudo critical exponents can be estimated."
    },
    {
        "anchor": "Director configurations of a nematic liquid crystal confined in a\n  toroidal geometry. A finite element study: Various director configurations of a nematic liquid crystal, confined in a\ntoroidal volume and subject to an external magnetic field, were evaluated\nnumerically by performing finite element calculations in three dimensions. The\nequilibrium director field is found from a minimization of the elasto-magnetic\nenergy of the nematic. The director at the inner surface of the torus is fixed,\neither along homeotropic or tangential direction. We consider both a\nhomogeneous and an azimuthal magnetic field, with its direction being in\nconflict with the respective surface anchoring.\n  The relative stability of topologically inequivalent configurations is\ninvestigated in dependence on the strength of the magnetic field and the\ngeometrical parameters of the confining torus. We find that in a toroidal\ngeometry the director \"escape\" from a disclination, which usually occurs in a\ncylindrical tube, is absolutely stable only for weak magnetic fields and\ntangential anchoring, whereas for homeotropic anchoring director fields\ncontaining disclination rings are more favorable. When a strong homogeneous\nmagnetic field is exerted laterally, the resulting director field is not any\nmore axially symmetric, instead, it reveals curved disclinations of finite\nlength.",
        "positive": "Sampling eigenmodes in colloidal solids: We study the properties of correlation matrices widely used in the\ncharacterisation of vibrational modes in colloidal materials. We show that the\neigenvectors in the middle of the spectrum are strongly mixed, but that at both\nthe top and the bottom of the spectrum it is possible to extract a good\napproximation to the true eigenmodes of an elastic system."
    },
    {
        "anchor": "Confinement of two-dimensional rods in slit pores and square cavities: Using Monte Carlo simulation, we analyse the behaviour of two-dimensional\nhard rods in four different types of geometric confinement: (i) a slit pore\nwhere the particles are confined between two parallel walls with homeotropic\nanchoring; (ii) a hybrid slit pore formed by a planar and a homeotropic wall;\nsquare cavities that frustrate the orientational order by imposing either (iii)\nhomeotropic or (iv) planar wall anchoring. We present results for the state\ndiagram as a function of the packing fraction and the degree of confinement.\nUnder extreme confinement, unexpected states appear with lower symmetries than\nthose of the corresponding stable states in bulk, such as the formation of\nstates that break the anchoring constraints or the symmetry imposed by the\nsurfaces. In both types of square cavities the particles form disclinations at\nintermediate densities. At high densities, however, the elastic stress is\nrelaxed via the formation of domain walls where the director rotates abruptly\nby ninety degrees.",
        "positive": "Coarse-grained modeling of polymers with end-on and side-on liquid\n  crystal moieties: effect of architecture: Mesogens, which are typically stiff rodlike or disklike molecules, are able\nto self-organize into liquid crystal (LC) phases in a certain temperature\nrange. Such mesogens, or LC groups, can be attached to polymer chains in\nvarious configurations including within the backbone (main-chain LC polymers)\nor at the ends of side-chains attached to the backbone in an end-on or side-on\nconfiguration (side-chain LC polymers or SCLCPs), which can display synergistic\nproperties arising from both their LC and polymeric character. At lower\ntemperatures, chain conformations may be significantly altered due to the\nmesoscale LC ordering, thus, when heating from the LC ordered state through the\nLC to isotropic phase transition, the chains return from a more stretched to a\nmore random coil conformation. This can cause macroscopic shape changes, which\ndepend significantly on the type of LC attachment and other architectural\nproperties of the polymer. Here, to study the structure-property relationships\nfor SCLCPs with a range of different architectures, we develop a coarse-grained\nmodel that includes torsional potentials along with LC interactions of a\nGay--Berne form. We create systems of different side chain lengths, chain\nstiffnesses, and LC attachment types, and track their structural properties as\na function of temperature. Our modeled systems indeed form a variety of\nwell-organized mesophase structures at low temperatures, and we predict higher\nLC to isotropic transition temperatures for the end-on side-chain systems than\nfor analogous side-on side-chain systems. Understanding these phase transitions\nand their dependence on polymer architecture can be useful in designing\nmaterials with reversible and controllable deformations."
    },
    {
        "anchor": "Optimal shepherding and transport of a flock: We investigate how a shepherd should move in order to effectively herd and\nguide a flock of agents towards a target. Using a detailed agent-based model\n(ABM) for the members of the flock, we pose and solve an optimization problem\nfor the shepherd that has to simultaneously work to keep the flock cohesive\nwhile coercing it towards a prescribed project. We find that three distinct\nstrategies emerge as potential solutions as a function of just two parameters:\nthe ratio of herd size to shepherd repulsion length and the ratio of herd speed\nto shepherd speed. We term these as: (i) mustering, in which the shepherd\ncircles the herd to ensure compactness, (ii) droving, in which the shepherd\nchases the herd in a desired direction, and (iii) driving, a hitherto\nunreported strategy where the flock surrounds a shepherd that drives it from\nwithin. A minimal dynamical model for the size, shape and position of the herd\ncaptures the effective behavior of the ABM, and further allows us to\ncharacterize the different herding strategies in terms of the behavior of the\nshepherd that librates (mustering), oscillates (droving) or moves steadily\n(driving). All together, our study yields a simple and intuitive classification\nof herding strategies that ought to be of general interest in the context of\ncontrolling the collective behavior of active matter.",
        "positive": "Polarity-dependent dielectric torque in nematic liquid crystals: The dielectric dispersion in the uniaxial nematic liquid crystals affects the\nswitching dynamics of the director, as the dielectric torque is determined by\nnot only the present values of the electric field and director but also by\ntheir past values. We demonstrate that this dielectric memory leads to an\nunusual contribution to the dielectric torque that is linear in the present\nfield and thus polarity-sensitive. This torque can be used to accelerate the\nswitch-off phase of director dynamics."
    },
    {
        "anchor": "PERM: A Monte Carlo Strategy for Simulating Polymers and Other Things: We describe a general strategy, PERM (Pruned-Enriched Rosenbluth Method), for\nsampling configurations from a given Gibbs-Boltzmann distribution. The method\nis not based on the Metropolis concept of establishing a Markov process whose\nstationary state is the wanted distribution. Instead, it starts off building\ninstances according to a biased distribution, but corrects for this by cloning\n\"good\" and killing \"bad\" configurations. In doing so, it uses the fact that\nnontrivial problems in statistical physics are high dimensional. Therefore,\ninstances are built step by step, and the final \"success\" of an instance can be\nguessed at an early stage. Using weighted samples, this is done so that the\nfinal distribution is strictly unbiased. In contrast to evolutionary\nalgorithms, the cloning/killing is done without simultaneously keeping a large\npopulation in computer memory. We apply this in large scale simulations of\nhomopolymers near the theta and unmixing critical points. In addition we sketch\nother applications, notably to polymers in confined geometries and to randomly\nbranched polymers. For theta polymers we confirm the very strong logarithmic\ncorrections found in previous work. For critical unmixing we essentially\nconfirm the Flory-Huggins mean field theory and the logarithmic corrections to\nit computed by Duplantier. We suggest that the latter are responsible for some\napparent violations of mean field behavior. This concerns in particular the\nexponent for the chain length dependence of the critical density which is 1/2\nin Flory-Huggins theory, but is claimed to be $\\approx 0.38$ in several\nexperiments.",
        "positive": "Dynamics of fibers in a wide microchannel: Dynamics of single flexible non-Brownian fibers, tumbling in a Poiseuille\nflow between two parallel solid plane walls, is studied with the use of the\nhydromultipole numerical code, based on the multipole expansion of the Stokes\nequations, corrected for lubrication. It is shown that for a wide range of the\nsystem parameters, the migration rate towards the middle plane of the channel\nincreases for fibers, which are closer to a wall, or are more flexible (less\nstiff), or are longer. The faster motion towards the channel center is\naccompanied by a slower translation along the flow and a larger fiber\ndeformation."
    },
    {
        "anchor": "Optimal cement paste yield stress for the production of stable cement\n  foams: Production of morphology-controlled cement foams remains challenging, mainly\ndue to bubble stability issues during cement setting. The use of cement paste\nwith high yield stress is expected to promote stability by damping intrinsic\nbubble kinetics. Here we show however that for given W/C ratio, fresh foam\nstability can be achieved instead by decreasing the yield stress of the cement\npaste. Indeed, in this low apparent yield stress regime, van der Waals\nattraction between cement grains is reduced and grains are allowed to be\nefficiently packed by bubbles, providing enhanced mechanical properties. This\nresult is obtained for two distinct additives used at controlled concentrations\nand without resorting to set accelerators, which highlights the general\nsignificance of the underlying stability mechanism. It offers a promising\nsolution to produce stable cement foams at high air content.",
        "positive": "Diffusiophoretic Enhancement of Mass Transfer by Nanofluids: Observations of an enhanced mass transfer in nanofluids have led to several\npropositions for the underlying cause, but none of them have been clearly\nestablished. Here, we reproduce the enhancement phenomenon within a glass\ncapillary containing fluorescein di-sodium dye solution on one side and alumina\nnanoparticle suspension on the other, avoiding convective interferences present\nearlier. The enhancement is explained by the counter-convective motion of the\ndye solution in response to the diffusiophoretic motion of the nanoparticles\ntowards a higher concentration of the dye. The velocity of the dye front agrees\nwith the theoretical estimate obtained from the diffusiophoretic velocity of\nalumina nanoparticles in a gradient of fluorescein di-sodium electrolyte\nsolution. With a suitably chosen nanofluid, it should now be possible to effect\nthe enhancement (or suppression) of mass transfer of a given solute."
    },
    {
        "anchor": "Thickness profiles of giant soap films: Production, drainage and stability of foams films, i.e. films in contact with\ntheir menisci, are fascinating problems that remain still unsolved. In this\narticle, we propose to explore the regime of large velocities and large film\nsizes. This one is not accessible in experiments classically conducted in the\nliterature, and allows us to study the regime of large extension and large\nextension rates. With our setup, we make soap films up to two meters high by\npulling a horizontal fishing line driven by belts out of a soapy solution at\nvelocities ranging from 20~cm/s to 250~cm/s. We characterize the thickness\nprofile of the central part of the film that behaves like a rubber band under\ntension. We show that its thickness profile is well described by a static model\nin which a homogeneous elastic film is stretched by its own weight. This leads\nto an exponential thickness profile with a characteristic length given by a\ncompetition between gravity and surface elasticity. The prefactor is fixed by\nthe shape and area of the film, governed by the fishing line motion but also by\na continuous extraction of foam film from the lateral menisci, thicker than the\ncentral part, and that progressively invades the film from its lateral\nboundaries. The model we propose captures the subtle interplay between gravity,\nfilm elasticity and film extraction and leads to predictions in good agreement\nwith our experimental data.",
        "positive": "Slow motions detection in polybutadiene through novel analyses of MSE\n  refocusing efficiency and spin-lattice relaxation: Novel methods to analyze NMR signals dominated by dipolar interaction are\napplied to the study of slow relaxation motions in polybutadiene approaching\nits glass transition temperature. The analysis is based on a recently developed\nmodel where the time dependence in an ensemble of dipolar interacting spin\npairs is described without resorting to the Anderson-Weiss approximation. The\nability to catch relevant features of the $\\alpha$ relaxation process is\nemphasized. In particular, it is shown that the temperature profile of the\nMagic Sandwich Echo efficiency carries information on the frequency profile of\nthe $\\alpha$-process. The analysis is corroborated by the temperature\ndependence of the spin-lattice relaxation time."
    },
    {
        "anchor": "Theory of Ferroelectric Nanoparticles in Nematic Liquid Crystals: Recent experiments have reported that ferroelectric nanoparticles have\ndrastic effects on nematic liquid crystals--increasing the isotropic-nematic\ntransition temperature by about 5 K, and greatly increasing the sensitivity to\napplied electric fields. To understand these effects, we develop a theory for\nthe statistical mechanics of ferroelectric nanoparticles in liquid crystals.\nThis theory predicts the enhancements of liquid-crystal properties, in good\nagreement with experiments. These predictions apply even when electrostatic\ninteractions are partially screened by moderate concentrations of ions.",
        "positive": "Local and global measures of the shear moduli of jammed disk packings: Strain-controlled isotropic compression gives rise to jammed packings of\nrepulsive, frictionless disks with either positive or negative global shear\nmoduli. We carry out computational studies to understand the contributions of\nthe negative shear moduli to the mechanical response of jammed disk packings.\nWe first decompose the ensemble-averaged, global shear modulus as $\\langle\nG\\rangle = (1-{\\cal F}_-) \\langle G_+ \\rangle + {\\cal F}_- \\langle G_-\\rangle$,\nwhere ${\\cal F}_-$ is the fraction of jammed packings with negative shear\nmoduli and $\\langle G_+\\rangle$ and $\\langle G_-\\rangle$ are the average values\nfrom packings with positive and negative moduli, respectively. We show that\n$\\langle G_+\\rangle$ and $\\langle|G_-|\\rangle$ obey different power-law scaling\nrelations above and below $pN^2 \\sim 1$. We then calculate analytically that\n${\\cal P}(G)$ is a Gamma distribution in the $pN^2 \\ll 1$ limit. As $pN^2$\nincreases, the skewness of ${\\cal P}(G)$ decreases and ${\\cal P}(G)$ becomes a\nskew-normal distribution with negative skewness in the $pN^2 \\gg 1$ limit. We\nalso partition jammed disk packings into subsystems using Delanunay\ntriangulation of the disk centers to calculate local shear moduli. We show that\nthe local shear moduli defined from groups of adjacent triangles can be\nnegative even when $G > 0$. The spatial correlation function of local shear\nmoduli $C({\\vec r})$ displays weak correlations for $pn_{\\rm sub}^2 < 10^{-2}$,\nwhere $n_{\\rm sub}$ is the number of particles within each subsystem. However,\n$C({\\vec r})$ begins to develop long-ranged spatial correlations with four-fold\nangular symmetry for $pn_{\\rm sub}^2 \\gtrsim 10^{-2}$."
    },
    {
        "anchor": "Athermal Fracture of Elastic Networks: How Rigidity Challenges the\n  Unavoidable Size-Induced Brittleness: By performing extensive simulations with unprecedentedly large system sizes,\nwe unveil how rigidity influences the fracture of disordered materials. We\nobserve the largest damage in networks with connectivity close to the isostatic\npoint and when the rupture thresholds are small. However, regardless of network\nand spring properties, a more brittle fracture is observed upon increasing\nsystem size. Differently from most of the fracture descriptors, the maximum\nstress drop, a proxy for brittleness, displays a universal non-monotonic\ndependence on system size. Based on this uncommon trend it is possible to\nidentify the characteristic system size $L^*$ at which brittleness kicks in.\nThe more the disorder in network connectivity or in spring thresholds, the\nlarger $L^*$. Finally, we speculate how this size-induced brittleness is\ninfluenced by thermal fluctuations.",
        "positive": "Ideal Linear Chain Polymers with Fixed Angular Momentum: The statistical mechanics of a linear non-interacting polymer chain with a\nlarge number of monomers is considered with fixed angular momentum. The radius\nof gyration for a linear polymer is derived exactly by functional integration.\nThis result is then compared to simulations done with a large number of\nnon-interacting rigid links at fixed angular momentum. The simulation agrees\nwith the theory up to finite size corrections. The simulations are also used to\ninvestigate the anisotropic nature of a spinning polymer. We find universal\nscaling of the polymer size along the direction of the angular momentum, as a\nfunction of rescaled angular momentum."
    },
    {
        "anchor": "Learning force fields from stochastic trajectories: When monitoring the dynamics of stochastic systems, such as interacting\nparticles agitated by thermal noise, disentangling deterministic forces from\nBrownian motion is challenging. Indeed, we show that there is an\ninformation-theoretic bound, the capacity of the system when viewed as a\ncommunication channel, that limits the rate at which information about the\nforce field can be extracted from a Brownian trajectory. This capacity provides\nan upper bound to the system's entropy production rate, and quantifies the rate\nat which the trajectory becomes distinguishable from pure Brownian motion. We\npropose a practical and principled method, Stochastic Force Inference, that\nuses this information to approximate force fields and spatially variable\ndiffusion coefficients. It is data efficient, including in high dimensions,\nrobust to experimental noise, and provides a self-consistent estimate of the\ninference error. In addition to forces, this technique readily permits the\nevaluation of out-of-equilibrium currents and the corresponding entropy\nproduction with a limited amount of data.",
        "positive": "Pattern Formation and Transport for Externally Driven Active Matter on\n  Periodic Substrates: We investigate the transport of interacting active run-and-tumble particles\nmoving under an external drift force through a periodic array of obstacles for\nincreasing drive amplitudes. For high activity where the system forms a\nmotility induced phase separated state, there are several distinct dynamic\nphases including a low drive pinned cluster phase, an intermediate uniform\nfluid, and a higher drive stripe crystal state. The transitions between the\nphases are correlated with signatures in the transport curves, differential\nmobility, and power spectra of the velocity fluctuations. In contrast, in the\nlow activity regime the transport curves and power spectra undergo little\nchange as a function of drive. We argue that in the high activity limit, the\nbehavior is similar to that of driven solids on periodic substrates, while in\nthe low activity limit the system behaves like a driven fluid."
    },
    {
        "anchor": "Localized Rayleigh Instability in Evaporation Fronts: A qualitatively different manifestation of the Rayleigh instability is\ndemonstrated, where, instead of the usual extended undulations and breakup of\nthe liquid into many droplets, the instability is localized, leading to an\nisolated narrowing of the liquid filament. The localized instability, caused by\na nonuniform curvature of the liquid domain, plays a key role in the\nevaporation of thin liquid films off solid surfaces.",
        "positive": "Cholesteric and screw-like nematic phases in systems of helical\n  particles: Recent numerical simulations of hard helical particle systems unveiled the\nexistence of a novel chiral nematic phase, termed screw-like, characterised by\nthe helical organization of the particle C$_2$ symmetry axes round the nematic\ndirector with periodicity equal to the particle pitch. This phase forms at high\ndensity and can follow a less dense uniform nematic phase, with relative\noccurrence of the two phases depending on the helix morphology. Since these\nnumerical simulations were conducted under three-dimensional periodic boundary\nconditions, two questions could remain open. Firstly, the real nature of the\nlower density nematic phase, expected to be cholesteric. Secondly, the\ninfluence that the latter, once allowed to form, may have on the existence and\nstability of the screw-like nematic phase. To address these questions, we have\nperformed Monte Carlo and molecular dynamics numerical simulations of helical\nparticle systems confined between two parallel repulsive walls. We have found\nthat removal of the periodicity constraint along one direction allows a\nrelatively-long-pitch cholesteric phase to form, in lieu of the uniform nematic\nphase, with helical axis perpendicular to the walls while the existence and\nstability of the screw-like nematic phase are not appreciably affected by this\nchange of boundary conditions."
    },
    {
        "anchor": "Ideal glass transitions for hard ellipsoids: For hard ellipsoids of revolution we calculate the phase diagram for the\nidealized glass transition. Our equations cover the glass physics in the full\nphase space, for all packing fractions and all aspect ratios X$_0$. With\nincreasing aspect ratio we find the idealized glass transition to become\nprimarily be driven by orientational degrees of freedom. For needle or plate\nlike systems the transition is strongly influenced by a precursor of a nematic\ninstability. We obtain three types of glass transition lines. The first one\n($\\phi_c^{(B)}$) corresponds to the conventional glass transition for spherical\nparticles which is driven by the cage effect. At the second one\n($\\phi_c^{(B')}$) which occurs for rather non-spherical particles a glass phase\nis formed which consists of domains. Within each domain there is a nematic\norder where the center of mass motion is quasi--ergodic, whereas the\ninter--domain orientations build an orientational glass. The third glass\ntransition line ($\\phi_c^{(A)}$) occurs for nearly spherical ellipsoids where\nthe orientational degrees of freedom with odd parity, e.g. 180$^o$ flips,\nfreeze independently from the positions.",
        "positive": "Role of inter-fibre bonds and their influence on sheet scale behaviour\n  of paper fibre networks: In fibrous paper materials, an exposure to a variation in moisture content\ncauses changes in the geometrical and mechanical properties. Such changes are\nstrongly affected by the inter-fibre bonds, which are responsible for the\ntransfer of the hygro-mechanical response from one fibre to its neighbours in\nthe network, resulting in sheet-scale deformation. Most models developed in\nliterature assume perfect bonding between fibres. In the 3D reality, there is\nsome flexibility in the bond region, even for the perfectly bonded fibres,\nbecause of the possibility of deformation gradients through the fibre\nthickness. In earlier 2D idealizations, perfectly bonded fibres were assumed,\nimplying full kinematic constraint through the entire thickness of the sheet.\nThe purpose of the present study is to assess the effect of this assumption.\nUsing a homogenization approach, a random network of fibres is generated with\ndifferent coverages and modelled using finite elements. In order to understand\nthe role of bonding between fibres on the hygro-expansive behaviour of a\nnetwork, a bond model is developed. In this model, the fibres are modelled\nusing 2D regular bulk finite elements and the bonds are represented by\ninterfacial elements of finite stiffness, which are introduced between each\npair of fibres bonded in the network. These embedded interfacial elements form\na connection between two respective fibres, allowing relative displacements\nbetween their mid-planes. The hygro-elastic response of networks obtained with\nthis bond model is investigated by varying the bond stiffness and the network\ncoverage under the application of mechanical loading and changes in moisture\ncontent. Furthermore, the bond model is used to analyse the influence of\ninter-fibre bonds on the anisotropic response of the paper fibre network."
    },
    {
        "anchor": "On the possibility of extending the Nore-Frenkel generalized law of\n  correspondent states to non-isotropic patchy interactions: Colloidal systems (and protein solutions) are often characterized by\nattractive interactions whose range is much smaller than the particle size.\nWhen this is the case and the interaction is spherical, systems obey a\ngeneralized law of correspondent states (GLCS), first proposed by Noro and\nFrenkel [ J.Chem.Phys. 113, 2941 (2000) ]. The thermodynamic properties become\ninsensitive to the details of the potential, depending only on the value of the\nsecond virial coefficient B_2 and the density $\\rho$. The GLCS does not\ngenerically hold for the case of non-spherical potentials. In this Letter we\nsuggest that when particles interact via short-ranged small-angular amplitude\npatchy interactions (so that the condition of only one bond per patch is\nfulfilled) it is still possible to generalize the GLCS close to the liquid-gas\ncritical point. Keywords: Colloids, Second Virial Coefficient, Proteins\ninteractions, Short-ranged attractive attractions.",
        "positive": "Crystal nucleation mechanism in melts of short polymer chains under\n  quiescent conditions and under shear flow: We present a molecular dynamics simulation study of crystal nucleation from\nundercooled melts of n-alkanes, and we identify the molecular mechanism of\nhomogeneous crystal nucleation under quiescent conditions and under shear flow.\nWe compare results for n-eicosane(C20) and n-pentacontahectane(C150), i.e. one\nsystem below the entanglement length and one above. Under quiescent conditions,\nwe observe that entanglement does not have an effect on the nucleation\nmechanism. For both chain lengths, the chains first align and then straighten\nlocally. Then the local density increases and finally positional ordering sets\nin. At low shear rates the nucleation mechanism is the same as under quiescent\nconditions, while at high shear rates the chains align and straighten at the\nsame time. We report on the effects of shear rate and temperature on the\nnucleation rates and estimate the critical shear rates, beyond which the\nnucleation rates increase with the shear rate. We show that the viscosity of\nthe system is not affected by the crystalline nuclei."
    },
    {
        "anchor": "Fast event-driven simulations for soft spheres: from dynamics to Laves\n  phase nucleation: Conventional molecular dynamics (MD) simulations struggle when simulating\nparticles with steeply varying interaction potentials, due to the need to use a\nvery short time step. Here, we demonstrate that an event-driven Monte Carlo\n(EDMC) approach first introduced by Peters and de With [Phys. Rev. E 85, 026703\n(2012)] represents an excellent substitute for MD in the canonical ensemble. In\naddition to correctly reproducing the static thermodynamic properties of the\nsystem, the EDMC method closely mimics the dynamics of systems of particles\ninteracting via the steeply repulsive Weeks-Chandler-Andersen (WCA) potential.\nIn comparison to time-driven MD simulations, EDMC runs faster by over an order\nof magnitude at sufficiently low temperatures. Moreover, the lack of a finite\ntime step in EDMC circumvents the need to trade accuracy against simulation\nspeed associated with the choice of time step in MD. We showcase the usefulness\nof this model to explore the phase behavior of the WCA model at extremely low\ntemperatures, and to demonstrate that spontaneous nucleation and growth of the\nLaves phases is possible at temperatures significantly lower than previously\nreported.",
        "positive": "Self-propulsion mechanism of active Janus particles in near-critical\n  binary mixtures: Gold-capped Janus particles immersed in a near-critical binary mixture can be\npropelled using illumination. We employ a non-isothermal diffuse interface\napproach to investigate the self-propulsion mechanism of a single colloid. We\nattribute the motion to body forces at the edges of a micronsized droplet that\nnucleates around the particle. Thus, the often-used concept of a surface\nvelocity cannot account for the self-propulsion. The particle's swimming\nvelocity is related to the droplet shape and size, which is determined by a\nso-called critical isotherm. Two distinct swimming regimes exist, depending on\nwhether the droplet partially or completely covers the particle. Interestingly,\nthe dependence of the swimming velocity on temperature is non-monotonic in both\nregimes."
    },
    {
        "anchor": "Collision induced spatial organization of microtubules: The dynamic behavior of microtubules in solution can be strongly modified by\ninteractions with walls or other structures. We examine here a microtubule\ngrowth model where the increase in size of the plus-end is perturbed by\ncollisions with other microtubules. We show that such a simple mechanism of\nconstrained growth can induce ordered structures and patterns from an initially\nisotropic and homogeneous suspension. First, microtubules self-organize locally\nin randomly oriented domains that grow and compete with each other. By imposing\neven a weak orientation bias, external forces like gravity or cellular\nboundaries may bias the domain distribution eventually leading to a macroscopic\nsample orientation.",
        "positive": "Interaction between two overall neutral charged microscopically\n  patterned surfaces: We study the interaction between heterogeneously charged surfaces in an\nelectrolyte solution by employing classical Density Functional Theory (cDFT)\nand Monte Carlo simulations. We observe a consistent behavior between cDFT and\nMonte Carlo simulations regarding force curves and two-dimensional density\nprofiles. Armed with the validated cDFT, we explore the system's behavior under\nparameters challenging to simulate directly .Our findings include impacts of\ndomain size, domain charge, domain charge configuration, and bulk electrolyte\nconcentration on the osmotic pressure. Remarkably, the force curve is more\nsensitive to the domain size for asymmetric configuration than symmetry\nconfiguration; the bulk concentration weakly influences the force curve\nindependent of the system configurations."
    },
    {
        "anchor": "Relaxation Times and Rheology in Dense Athermal Suspensions: We study the jamming transition in a model of elastic particles under shear\nat zero temperature. The key quantity is the relaxation time $\\tau$ which is\nobtained by stopping the shearing and letting energy and pressure decay to\nzero. At many different densities and initial shear rates we do several such\nrelaxations to determine the average $\\tau$. We establish that $\\tau$ diverges\nwith the same exponent as the viscosity and determine another exponent from the\nrelation between $\\tau$ and the coordination number. Though most of the\nsimulations are done for the model with dissipation due to the motion of\nparticles relative to an affinely shearing substrate (the RD$_0$ model), we\nalso examine the CD$_0$ model, where the dissipation is instead due to velocity\ndifferences of disks in contact, and confirm that the above-mentioned exponent\nis the same for these two models. We also consider finite size effects on both\n$\\tau$ and the coordination number.",
        "positive": "Coupling between criticality and gelation in \"sticky\" spheres: A\n  structural analysis: We combine experiments and simulations to study the link between criticality\nand gelation in sticky spheres. We employ confocal microscopy to image\ncolloid-polymer mixtures, and Monte Carlo simulations of the square-well (SW)\npotential as a reference model. To this end, we map our experimental samples\nonto the SW model. We find excellent structural agreement between experiments\nand simulations, both for locally favored structures at the single particle\nlevel and large-scale fluctuations at criticality. We follow in detail the\nrapid structural change of the critical fluid when approaching the gas-liquid\nbinodal and highlight the role of critical density fluctuations for this\nstructural crossover. Our results link the arrested spinodal decomposition to\nlong-lived energetically favored structures, which grow even away from the\nbinodal due to the critical scaling of the bulk correlation length and static\nsusceptibility."
    },
    {
        "anchor": "Thermal vacancies in close-packing solids: Based on Stillinger's version of cell cluster theory, we derive an expression\nfor the equilibrium concentration of thermal monovacancies in solids which\nallows for a transparent interpretation of the vacancy volume and the\nenergetic/entropic part in the corresponding Gibbs energy of vacancy formation\n$\\Delta G_{\\rm v}$. For the close--packing crystals of the hard sphere and\nLennard--Jones model systems very good agreement with simulation data is found.\nApplication to metals through the embedded--atom method (EAM) reveals a strong\nsensitivity of the variation of $\\Delta G_{\\rm v}$ with temperature to details\nof the EAM potential. Our truncation of the cell cluster series allows for an\napproximate, but direct measurement of crystal free energies and vacancy\nconcentration in colloidal model systems using laser tweezers.",
        "positive": "Free-energy landscapes of DNA and its assemblies: Perspectives from\n  coarse-grained modelling: This chapter will provide an overview of how characterizing free-energy\nlandscapes can provide insights into the biophysical properties of DNA, as well\nas into the behaviour of the DNA assemblies used in the field of DNA\nnanotechnology. The landscapes for these complex systems are accessible through\nthe use of accurate coarse-grained descriptions of DNA. Particular foci will be\nthe landscapes associated with DNA self-assembly and mechanical deformation,\nwhere the latter can arise from either externally imposed forces or internal\nstresses."
    },
    {
        "anchor": "Characterizing the bending and flexibility induced by bulges in DNA\n  duplexes: Advances in DNA nanotechnology have stimulated the search for simple motifs\nthat can be used to control the properties of DNA nanostructures. One such\nmotif, which has been used extensively in structures such as polyhedral cages,\ntwo-dimensional arrays, and ribbons, is a bulged duplex, that is two helical\nsegments that connect at a bulge loop. We use a coarse-grained model of DNA to\ncharacterize such bulged duplexes. We find that this motif can adopt structures\nbelonging to two main classes: one where the stacking of the helices at the\ncenter of the system is preserved, the geometry is roughly straight and the\nbulge is on one side of the duplex, and the other where the stacking at the\ncenter is broken, thus allowing this junction to act as a hinge and increasing\nflexibility. Small loops favor states where stacking at the center of the\nduplex is preserved, with loop bases either flipped out or incorporated into\nthe duplex. Duplexes with longer loops show more of a tendency to unstack at\nthe bulge and adopt an open structure. The unstacking probability, however, is\nhighest for loops of intermediate lengths, when the rigidity of single-stranded\nDNA is significant and the loop resists compression. The properties of this\nbasic structural motif clearly correlate with the structural behavior of\ncertain nano-scale objects, where the enhanced flexibility associated with\nlarger bulges has been used to tune the self-assembly product as well as the\ndetailed geometry of the resulting nanostructures.",
        "positive": "Low-frequency vibrational modes of stable glasses: We numerically study the evolution of the vibrational density of states\n$D(\\omega)$ of zero-temperature glasses when their kinetic stability is varied\nover an extremely broad range, ranging from poorly annealed glasses obtained by\ninstantaneous quenches from above the onset temperature, to ultrastable glasses\nobtained by quenching systems thermalised below the experimental glass\ntemperature. The low-frequency part of the density of states splits between\nextended and quasi-localized modes. Extended modes exhibit a boson peak\ncrossing over to Debye behaviour ($D(\\omega) \\sim \\omega^2$) at low-frequency,\nwith a strong correlation between the two regimes. Quasi-localized modes\ninstead obey $D(\\omega) \\sim \\omega^4$, irrespective of the glass stability.\nHowever, the prefactor of this quartic law becomes smaller in more stable\nglasses, and the corresponding modes become more localized and sparser. Our\nwork is the first numerical observation of quasi-localized modes in a regime\nrelevant to experiments, and it establishes a direct connection between glass\nstability and soft vibrational motion in amorphous solids."
    },
    {
        "anchor": "Simulation studies of a phenomenological model for elongated virus\n  capsid formation: We study a phenomenological model in which the simulated packing of hard,\nattractive spheres on a prolate spheroid surface with convexity constraints\nproduces structures identical to those of prolate virus capsid structures. Our\nsimulation approach combines the traditional Monte Carlo method with a modified\nmethod of random sampling on an ellipsoidal surface and a convex hull searching\nalgorithm. Using this approach we identify the minimum physical requirements\nfor non-icosahedral, elongated virus capsids, such as two aberrant flock house\nvirus (FHV) particles and the prolate prohead of bacteriophage $\\phi_{29}$, and\ndiscuss the implication of our simulation results in the context of recent\nexperimental findings. Our predicted structures may also be experimentally\nrealized by evaporation-driven assembly of colloidal spheres.",
        "positive": "Metachronal waves in concentrations of swimming Turbatrix aceti\n  nematodes and an oscillator chain model for their coordinated motions: At high concentration, free swimming nematodes known as vinegar eels ({\\it\nTurbatrix aceti}), collectively exhibit metachronal waves near a boundary. We\nfind that the frequency of the collective traveling wave is lower than that of\nthe freely swimming organisms. We explore models based on a chain of\noscillators with nearest neighbor interactions that inhibit oscillator phase\nvelocity. The phase of each oscillator represents the phase of the motion of\nthe eel's head back and forth about its mean position. A strongly interacting\ndirected chain model mimicking steric repulsion between organisms robustly\ngives traveling wave states and can approximately match the observed wavelength\nand oscillation frequency of the observed traveling wave. We predict body\nshapes assuming that waves propagate down the eel body at a constant speed. The\nphase oscillator model that impedes eel head overlaps also reduces close\ninteractions throughout the eel bodies."
    },
    {
        "anchor": "Biopolymer dynamics driven by helical flagella: Microbial flagellates typically inhabit complex suspensions of polymeric\nmaterial which can impact the swimming speed of motile microbes, filter-feeding\nof sessile cells, and the generation of biofilms. There is currently a need to\nbetter understand how the fundamental dynamics of polymers near active cells or\nflagella impacts these various phenomena, in particular the hydrodynamic and\nsteric influence of a rotating helical filament on suspended polymers. Our\nStokesian dynamics simulations show that as a stationary rotating helix pumps\nfluid along its long axis, polymers migrate radially inwards while being\nelongated. We observe that the actuation of the helix tends to increase the\nprobability of finding polymeric material within its pervaded volume. This\naccumulation of polymers within the vicinity of the helix is stronger for\nlonger polymers. We further analyse the stochastic work performed by the helix\non the polymers and show that this quantity is positive on average and\nincreases with polymer contour length.",
        "positive": "Recovery of free energy branches in single molecule experiments: We present a method for determining the free energy of coexisting states from\nirreversible work measurements. Our approach is based on a fluctuation relation\nthat is valid for dissipative transformations in partially equilibrated\nsystems. To illustrate the validity and usefulness of the approach, we use\noptical tweezers to determine the free energy branches of the native and\nunfolded states of a two-state molecule as a function of the pulling control\nparameter. We determine, within 0.6 kT accuracy, the transition point where the\nfree energies of the native and the unfolded states are equal."
    },
    {
        "anchor": "Coarse-grained simulations of flow-induced nucleation in\n  semi-crystalline polymers: We perform kinetic Monte Carlo simulations of flow-induced nucleation in\npolymer melts with an algorithm that is tractable even at low undercooling. The\nconfiguration of the non-crystallized chains under flow is computed with a\nrecent non-linear tube model. Our simulations predict both enhanced nucleation\nand the growth of shish-like elongated nuclei for sufficiently fast flows. The\nsimulations predict several experimental phenomena and theoretically justify a\npreviously empirical result for the flow-enhanced nucleation rate. The\nsimulations are highly pertinent to both the fundamental understanding and\nprocess modeling of flow-induced crystallization in polymer melts.",
        "positive": "Low-temperature anomalies of a vapor deposited glass: We investigate the low temperature properties of two-dimensional\nLennard-Jones glass films, prepared in silico both by liquid cooling and by\nphysical vapor deposition. We identify deep in the solid phase a crossover\ntemperature $T^*$, at which slow dynamics and enhanced heterogeneity emerge.\nAround $T^*$, localized defects become visible, leading to vibrational\nanomalies as compared to standard solids. We find that on average, $T^*$\ndecreases in samples with lower inherent structure energy, suggesting that such\nanomalies will be suppressed in ultra-stable glass films, prepared both by very\nslow liquid cooling and vapor deposition."
    },
    {
        "anchor": "On propagation of axisymmetric waves in pressurized functionally graded\n  elastomeric hollow cylinders: Soft materials can be designed with a functionally graded (FG) property for\nspecific applications. In this paper, we analyze the axisymmetric guided wave\npropagation in a pressurized FG elastomeric hollow cylinder. The cylinder is\nsubjected to a combined action of axial pre-stretch and pressure difference\napplied to the inner and outer cylindrical surfaces. We consider both torsional\nwaves and longitudinal waves propagating in the FG cylinder made of\nincompressible isotropic elastomer, which is characterized by the Mooney-Rivlin\nstrain energy function but with the material parameters varying with the radial\ncoordinate in an affine way. The pressure difference generates an inhomogeneous\ndeformation field in the FG cylinder, which dramatically complicates the\nsuperimposed wave problem described by the small-on-large theory. A\nparticularly efficient approach is hence employed which combines the\nstate-space formalism for the incremental wave motion with the approximate\nlaminate or multi-layer technique. Dispersion relations for the two types of\naxisymmetric guided waves are then derived analytically. The accuracy and\nconvergence of the proposed approach is validated numerically. The effects of\nthe pressure difference, material gradient, and axial pre-stretch on both the\ntorsional and the longitudinal wave propagation characteristics are discussed\nin detail through numerical examples. It is found that the frequency of\naxisymmetric waves depends nonlinearly on the pressure difference and the\nmaterial gradient, and an increase in the material gradient enhances the\ncapability of the pressure difference to adjust the wave behavior in the FG\ncylinder.",
        "positive": "The role of interstitial gas in determining the impact response of\n  granular beds: We examine the impact of a solid sphere into a fine-grained granular bed.\nUsing high-speed X-ray radiography we track both the motion of the sphere and\nlocal changes in the bed packing fraction. Varying the initial packing density\nas well as the ambient gas pressure, we find a complete reversal in the effect\nof interstitial gas on the impact response of the bed: The dynamic coupling\nbetween gas and grains allows for easier penetration in initially loose beds\nbut impedes penetration in more densely packed beds. High-speed imaging of the\nlocal packing density shows that these seemingly incongruous effects have a\ncommon origin in the resistance to bed packing changes caused by interstitial\nair."
    },
    {
        "anchor": "Yielding transition of a two dimensional glass former under athermal\n  cyclic shear deformation: We study numerically the yielding transition of a two dimensional model glass\nsubjected to athermal quasi-static cyclic shear deformation, with the aim of\ninvestigating the effect on the yielding behaviour of the degree of annealing,\nwhich in turn depends on the preparation protocol. We find two distinct regimes\nof annealing separated by a threshold energy. Poorly annealed glasses\nprogressively evolve towards the threshold energy as the strain amplitude is\nincreased towards the yielding value. Well annealed glasses with initial\nenergies below the threshold energy exhibit stable behaviour, with negligible\nchange in energy with increasing strain amplitude, till they yield.\nDiscontinuities in energy and stress at yielding increase with the degree of\nannealing, consistently with recent results found in three dimensions. We\nobserve significant structural change with strain amplitude that closely\nmirrors the changes in energy and stresses. We investigate groups of particles\nthat are involved in plastic rearrangements. We analyse the distributions of\navalanche sizes, of clusters of connected rearranging particles, and related\nquantities, employing finite size scaling analysis. We verify previously\ninvestigated relations between exponents characterising these distributions,\nand a newly proposed relation between exponents describing avalanche and\ncluster size distributions.",
        "positive": "Signatures of shear thinning-thickening transition in dense athermal\n  shear flows: In non-equilibrium molecular dynamics simulations of dense athermal shear\nflows, we observe the transition from shear thinning to shear thickening at a\ncrossover shear rate $\\dot\\gamma_c$. Shear thickening occurs when $\\frac{{\\rm d\n(ln} T_g)}{{\\rm d (ln}\\dot\\gamma)}>2$ with $T_g$ the granular temperature. At\nthe transition, the pair distribution function shows the strongest anisotropy.\nMeanwhile, the dynamics undergo apparent changes, signified by distinct scaling\nbehaviors of the mean squared displacement and relaxation time on both sides of\n$\\dot\\gamma_c$. These features serve as robust signatures of the shear\nthinning-thickening transition."
    },
    {
        "anchor": "On the capillary stress tensor in wet granular materials: This paper presents a micromechanical study of unsaturated granular media in\nthe pendular regime, based upon numerical experiments using the discrete\nelement method, compared to a microstructural elastoplastic model. Water\neffects are taken into account by adding capillary menisci at contacts and\ntheir consequences in terms of force and water volume are studied. Simulations\nof triaxial compression tests are used to investigate both macro and\nmicro-effects of a partial saturation. The results provided by the two methods\nappear to be in good agreement, reproducing the major trends of a partially\nsaturated granular assembly, such as the increase in the shear strength and the\nhardening with suction. Moreover, a capillary stress tensor is exhibited from\ncapillary forces by using homogenisation techniques. Both macroscopic and\nmicroscopic considerations emphasize an induced anisotropy of the capillary\nstress tensor in relation with the pore fluid distribution inside the material.\nIn so far as the tensorial nature of this fluid fabric implies shear effects on\nthe solid phase associated with suction, a comparison has been made with the\nstandard equivalent pore pressure assumption. It is shown that water effects\ninduce microstrural phenomena that cannot be considered at the macro level,\nparticularly when dealing with material history. Thus, the study points out\nthat unsaturated soil stress definitions should include, besides the\nmacroscopic stresses such as the total stress, the microscopic interparticle\nstresses such as the ones resulting from capillary forces, in order to\ninterpret more precisely the implications of the pore fluid on the mechanical\nbehaviour of granular materials.",
        "positive": "Fast estimation of ion-pairing for screening electrolytes: A cluster can\n  approximate a bulk liquid: The propensity for ion-pairing can often dictate the thermodynamic and\nkinetic properties of electrolyte solutions. Fast and accurate estimates of\nion-pairing can thus be extremely valuable for supplementing design and\nscreening efforts for novel electrolytes. Here, we introduce an efficient\ncluster model to estimate the local ion-pair potential-of-mean-force (PMF)\nbetween ionic solutes in electrolytes. The model incorporates an ion-pair and a\nfew layers of explicit solvent in a gas-phase cluster and leverages an enhanced\nsampling approach to achieve high efficiency and accuracy. We employ harmonic\nrestraints to prevent solvent escape from the cluster and restrict sampling of\nlarge inter ion distances. We develop a Cluster Ion-Pair Sampling (CLIPS) tool\nthat implements our cluster model and demonstrate its potential utility for\nscreening simple and poly-electrolyte systems."
    },
    {
        "anchor": "A real-space renormalization group for jamming: Jamming occurs in granular materials, as well as in emulsions, dense\nsuspensions, and other amorphous, particulate systems. When the packing\nfraction $\\phi$, defined as the ratio of particle volume to system volume, is\nincreased past a critical value $\\phi_c$, a liquid-solid phase transition\noccurs, and grains are no longer able to rearrange. Previous studies have shown\nevidence of spatial correlations that diverge near $\\phi = \\phi_c$, but there\nhas been no explicit spatial renormalization group (RG) scheme that has\ncaptured this transition. Here, I present a candidate for such a scheme, using\na block-spin-like transformation of a randomly vacated lattice of grains. I\ndefine a real-space RG transformation based on local mechanical stability. This\nmodel displays a critical packing fraction $\\phi_c$ and gives estimates of\ncritical exponents in two and three dimensions.",
        "positive": "Imperfections in focal conic domains: the role of dislocations: It is usual to think of Focal Conic Domains (FCD) as perfect geometric\nconstructions in which the layers are folded into Dupin cyclides, about an\nellipse and a hyperbola that are conjugate. This ideal picture is often far\nfrom reality. We have investigated in detail the FCDs in several materials\nwhich have a transition from a smectic A (SmA) to a nematic phase. The ellipse\nand the hyperbola are seldom perfect, and the FCD textures also suffer large\ntransformations (in shape or/and in nature) when approaching the transition to\nthe nematic phase, or appear imperfect on cooling from the nematic phase. We\ninterpret these imperfections as due to the interaction of FCDs with\ndislocations. We analyze theoretically the general principles subtending the\ninteraction mechanisms between FCDs and finite Burgers vector dislocations,\nnamely the formation of kinks on disclinations, to which dislocations are\nattached, and we present models relating to some experimental results. Whereas\nthe principles of the interactions are very general, their realizations can\ndiffer widely in function of the boundary conditions."
    },
    {
        "anchor": "Equilibrium gels of limited valence colloids: Gels are low-packing arrested states of matter which are able to support\nstress. On cooling, limited valence colloidal particles form open networks\nstabilized by the progressive increase of the interparticle bond lifetime.\nThese gels, named equilibrium gels, are the focus of this review article.\nDifferently from other types of colloidal gels, equilibrium gels do not require\nan underlying phase separation to form. Oppositely, they form in a region of\ndensities deprived of thermodynamic instabilities. Limited valence equilibrium\ngels neither coarsen nor age with time.",
        "positive": "Shape-free theory for the self-assembly kinetics in macromolecular\n  systems: Self-assembly kinetics is usually described by approaches which assume that\nthe shape of the aggregates has a definite form (e.g., spherical, cylindrical,\ncubic, etc), however that is unlikely to be the case in many finite-sized\nmacromolecular and colloidal systems. Here we consider a simple aggregation\nmodel which displays a first-order phase transition in order to illustrate a\nrate theory based on microcanonical analysis that allows one to obtain a\nshape-free description of its self-assembly kinetics. Stochastic simulations\nare performed to validate our approach and demonstrate how the equilibrium\nthermostatistical properties of the system can be related to the\ntemperature-dependent rate constants. As a model-independent kinetic approach,\nit may provide experimentalists a reliable method to reconstruct free-energy\nprofiles and microcanonical entropies from kinetic data."
    },
    {
        "anchor": "Sonine approximation for collisional moments of granular gases of\n  inelastic rough spheres: We consider a dilute granular gas of hard spheres colliding inelastically\nwith coefficients of normal and tangential restitution $\\alpha$ and $\\beta$,\nrespectively. The basic quantities characterizing the distribution function\n$f(\\mathbf{v},\\bm{\\omega})$ of linear ($\\mathbf{v}$) and angular\n($\\bm{\\omega}$) velocities are the second-degree moments defining the\ntranslational ($T^\\text{tr}$) and rotational ($T^\\text{rot}$) temperatures. The\ndeviation of $f$ from the Maxwellian distribution parameterized by\n$T^\\text{tr}$ and $T^\\text{rot}$ can be measured by the cumulants associated\nwith the fourth-degree velocity moments. The main objective of this paper is\nthe evaluation of the collisional rates of change of these second- and\nfourth-degree moments by means of a Sonine approximation. The results are\nsubsequently applied to the computation of the temperature ratio\n$T^\\text{rot}/T^\\text{tr}$ and the cumulants of two paradigmatic states: the\nhomogeneous cooling state and the homogeneous steady state driven by a\nwhite-noise stochastic thermostat. It is found in both cases that the\nMaxwellian approximation for the temperature ratio does not deviate much from\nthe Sonine prediction. On the other hand, non-Maxwellian properties measured by\nthe cumulants cannot be ignored, especially in the homogeneous cooling state\nfor medium and small roughness. In that state, moreover, the cumulant directly\nrelated to the translational velocity differs in the quasi-smooth limit\n$\\beta\\to -1$ from that of pure smooth spheres ($\\beta=-1$). This singular\nbehavior is directly related to the unsteady character of the homogeneous\ncooling state and thus it is absent in the stochastic thermostat case.",
        "positive": "A constitutive model for brittle granular materials considering the\n  competition between breakage and dilation: A constitutive model is presented for brittle granular materials based on a\nrecent reformulation of the breakage mechanics theory. Compared with previous\nbreakage mechanics-based models, the proposed model is improved to capture\nstrain softening towards the critical state following the peak stress observed\nin dense specimens under shearing, and simultaneous evolution of breakage and\ndilation. Considering the competition between dilation and particle breakage\nallows the model to capture breakage-induced reduction in dilatancy and peak\nstrength as confining pressure increases. The influence of the model parameters\non the overall material response is described through a detailed calibration\nprocedure based on a benchmark experimental dataset. Comparison of the results\nof drained triaxial compression experiments on two sands with the predictions\nof the model indicates that the enriched model successfully captures strain\nsoftening in dilatant specimens, the shearing-driven evolution of stress-strain\nbehavior towards the critical state at different confinement levels, the\ntransition from dilatant to compactive volumetric response, and the evolution\nof particle grading due to distributed breakage events. The proposed framework\nis capable of qualitatively reproducing the experimentally observed\nstress-dilatancy-breakage relationship in brittle granular materials in the low\npressure regime."
    },
    {
        "anchor": "Debye-H\u00fcckel potential at an interface between two media: Electrostatic interactions between point charges embedded into interfaces\nseparating dielectric media are omnipresent in soft matter systems and often\ncontrol their stability. Such interactions are typically complicated and do not\nresemble their bulk counterparts. For instance, the electrostatic potential of\na point charge at an air-water interface falls off as $r^{-3}$, where $r$ is\nthe distance from the charge, exhibiting a dipolar behaviour. This behaviour is\noften assumed to be generic, and is widely referred to when interpreting\nexperimental results. Here we explicitly calculate the in-plane potential of a\npoint charge at an interface between two electrolyte solutions with different\ndielectric permittivities and Debye screening lengths. We show that the\nasymptotic behaviour of this potential is neither a dipole, which characterises\nthe potential at air-water interfaces, nor a screened monopole, which describes\nthe bulk behaviour in a single electrolyte solution. By considering the same\nproblem in arbitrary dimensions, we find that the physics behind this\ndifference can be traced to the asymmetric propagation of the interaction in\nthe two media. Our results are relevant, for instance, to understand the\nphysics of charged colloidal particles trapped at oil-water interfaces.",
        "positive": "Hierarchy of Geometrical Frustration in Elastic Ribbons:\n  shape-transitions and energy scaling obtained from a general asymptotic\n  theory: Geometrically frustrated elastic ribbons exhibit, in many cases, significant\nchanges in configuration depending on the relation between their width and\nthickness. We show that the existence of such a transition, and the scaling at\nwhich it occurs, strongly depend on the system considered. Using an asymptotic\napproach, treating the width as a small parameter, we find the leading energy\nterms resulting from the frustration and predict the existence and scaling of\nthe shape transition. We study in detail 5 different types of frustrated\nribbons with a different morphological dependence on ribbon's width: a sharp\nshape-transition at a critical width, a moderate transition with an\nintermediate regime, and no transition at all. We show that the predictions of\nour approach match experimental results from two different experimental\nsystems: prestressed rubber bilayers and 4D printed thermoplastics, in a wide\nvariety of geometric settings."
    },
    {
        "anchor": "Mixing-induced anisotropic correlations in molecular crystalline systems: We investigate the structure of mixed thin films composed of pentacene (PEN)\nand diindenoperylene (DIP) using X-ray reflectivity and grazing incidence X-ray\ndiffraction. For equimolar mixtures we observe vanishing in-plane order\ncoexisting with an excellent out-of-plane order, a yet unreported disordering\nbehavior in binary mixtures of organic semiconductors, which are crystalline in\ntheir pure form. One approach to rationalize our findings is to introduce an\nanisotropic interaction parameter in the framework of a mean field model. By\ncomparing the structural properties with those of other mixed systems, we\ndiscuss the effects of sterical compatibility and chemical composition on the\nmixing behavior, which adds to the general understanding of interactions in\nmolecular mixtures.",
        "positive": "Solvent-Dependent Critical Properties of Polymer Adsorption: Advanced chain-growth computer simulation methodologies have been employed\nfor a systematic statistical analysis of the critical behavior of a polymer\nadsorbing at a substrate. We use finitesize scaling techniques to investigate\nthe solvent-quality dependence of critical exponents, critical temperature, and\nthe structure of the phase diagram. Our study covers all solvent effects from\nthe limit of super-self-avoiding walks, characterized by effective\nmonomer-monomer repulsion, to poor solvent conditions that enable the formation\nof compact polymer structures. The results significantly benefit from taking\ninto account corrections to scaling."
    },
    {
        "anchor": "An Analysis of the Gel Point of Polymer Model Networks by Computer\n  Simulations: The gel point of end-linked model networks is determined from computer\nsimulation data. It is shown that the difference between the true gel point\nconversion, $p_{\\text{c}}$, and the ideal mean field prediction for the gel\npoint, $p_{\\text{c,id}}$, is a function of the average number of cross-links\nper pervaded volume of a network strand, $P$, and thus, contains an explicit\ndependence on junction functionality $f$. On the contrary, the amount of\nintra-molecular reactions at the gel point is independent of $f$ in a first\napproximation and exhibits a different power law dependence on the overlap\nnumber of elastic strands as compared to the gel point delay\n$p_{\\text{c}}-p_{\\text{c,id}}$. Therefore, $p_{\\text{c}}-p_{\\text{c,id}}$\ncannot be predicted from intra-molecular reactions and vice versa in contrast\nto a long standing proposal in literature. Instead, the main contribution to\n$p_{\\text{c}}-p_{\\text{c,id}}$ for $P>1$ arises from the extra bonds (XB)\nneeded to bridge the gaps between giant molecules separated in space and scales\nroughly $\\propto\\left(P-1\\right)^{-1/2}$. Further corrections to scaling are\ndue to non-ideal reaction kinetics, composition fluctuations, and incompletely\nscreened excluded volume, which are discussed briefly.",
        "positive": "A possible mechanism for cold denaturation of proteins at high pressure: We study cold denaturation of proteins at high pressures. Using\nmulticanonical Monte Carlo simulations of a model protein in a water bath, we\ninvestigate the effect of water density fluctuations on protein stability. We\nfind that above the pressure where water freezes to the dense ice phase\n($\\approx2$ kbar), the mechanism for cold denaturation with decreasing\ntemperature is the loss of local low-density water structure. We find our\nresults in agreement with data of bovine pancreatic ribonuclease A."
    },
    {
        "anchor": "Thermodynamics of Ion Solvation and Differential Adsorption at\n  Liquid-Liquid Interfaces and Membranes: We construct a mean-field formulation of the thermodynamics of ion solvation\nin immiscible polar binary mixtures. Assuming an equilibrium planar interface\nseparating two semi-infinite regions of different constant dielectric medium,\nwe study the electrostatic phenomenon of differential adsorption of ions at the\ninterface. Using general thermodynamic considerations, we construct the\nmean-field $\\Omega$-potential and demonstrate the spontaneous formation of an\nelectric double-layer around the interface necessarily follow. In our\nframework, we can also relate both the bulk ion densities in the two phases and\nthe distribution potential across the interface to the fundamental Born free\nenergy of ion polarization. We further illustrate this selective ion adsorption\nphenomenon in respective examples of fully permeable membranes that are\nneutral, negative, or positive in charge polarity.",
        "positive": "The role of boundaries for displacements and motion in two-dimensional\n  fluid or elastic films and membranes: Thin fluid or elastic films and membranes are found in nature and technology,\nfor instance, as confinements of living cells or in loudspeakers. When applying\na net force, resulting flows in an unbounded two-dimensional incompressible\nlow-Reynolds-number fluid or displacements in a two-dimensional linearly\nelastic solid seem to diverge logarithmically with the distance from the force\ncenter, which has led to some debate. Recently, we have demonstrated that such\ndivergences cancel when the total (net) force vanishes. Here, we illustrate\nthat, if a net force is present, the boundaries play a prominent role. Already\na single no-slip boundary regulates the flow and displacement fields and leads\nto their decay to leading order inversely in distance from a force center and\nthe boundary. In other words, it is the boundary that stabilizes the system in\nthis situation, unlike the three-dimensional case, where an unbounded medium by\nitself is able to absorb a net force. We quantify the mobility and\ndisplaceability of an inclusion as a function of the distance from the\nboundary, as well as interactions between different inclusions. In the case of\nfree-slip boundary conditions, a kinked boundary is necessary to achieve\nstabilization."
    },
    {
        "anchor": "Optimizing end-labeled free-solution electrophoresis by increasing the\n  hydrodynamic friction of the drag-tag: We study the electrophoretic separation of polyelectrolytes of varying\nlengths by means of end-labeled free-solution electrophoresis (ELFSE). A\ncoarse-grained molecular dynamics simulation model, using full electrostatic\ninteractions and a mesoscopic Lattice Boltzmann fluid to account for\nhydrodynamic interactions, is used to characterize the drag coefficients of\ndifferent label types: linear and branched polymeric labels, as well as\ntransiently bound micelles.\n  It is specifically shown that the label's drag coefficient is determined by\nits hydrodynamic size, and that the drag per label monomer is largest for\nlinear labels. However, the addition of side chains to a linear label offers\nthe possibility to increase the hydrodynamic size, and therefore the label\nefficiency, without having to increase the linear length of the label, thereby\nsimplifying synthesis. The third class of labels investigated, transiently\nbound micelles, seems very promising for the usage in ELFSE, as they provide a\nsignificant higher hydrodynamic drag than the other label types.\n  The results are compared to theoretical predictions, and we investigate how\nthe efficiency of the ELFSE method can be improved by using smartly designed\ndrag-tags.",
        "positive": "Environmental Memory Boosts Group Formation of Clueless Individuals: The formation of groups of interacting individuals improves performance and\nfitness in many decentralised systems, from micro-organisms to social insects,\nfrom robotic swarms to artificial intelligence algorithms. Often, group\nformation and high-level coordination in these systems emerge from individuals\nwith limited information-processing capabilities implementing low-level rules\nof communication to signal to each other. Here, we show that, even in a\ncommunity of clueless individuals incapable of processing information and\ncommunicating, a dynamic environment can coordinate group formation by\ntransiently storing memory of the earlier passage of individuals. Our results\nidentify a new mechanism of indirect coordination via shared memory that is\nprimarily promoted and reinforced by dynamic environmental factors, thus\novershadowing the need for any form of explicit signalling between individuals.\nWe expect this pathway to group formation to be relevant for understanding and\ncontrolling self-organisation and collective decision making in both living and\nartificial active matter in real-life environments."
    },
    {
        "anchor": "Optical trapping of colloids at a liquid-liquid interface: We demonstrate the realization of (laterally) optically bounded colloidal\nstructures on a liquid-liquid interface of an emulsion droplet. We use DNA\ntethers to graft the particles to the droplet surface, effectively confining\nthem to a quasi-2D plane with minimum constraints on the lateral movement even\nwhen optically trapped in a common single-beam configuration. We show that\nrelatively weak interactions such as depletion can be measured in the optically\nbounded crystals by video-microscopy imaging and analysis. This illustrates the\npossible use of our system as template to study optically controlled quasi\ntwo-dimensional colloidal assembly on liquid-liquid interfaces.",
        "positive": "Frustration of freezing in a two dimensional hard-core fluid due to\n  particle shape anisotropy: The freezing mechanism suggested for a fluid composed of hard disks [Huerta\net al., Phys. Rev. E, 2006, 74, 061106] is used here to probe the\nfluid-to-solid transition in a hard-dumbbell fluid composed of overlapping hard\ndisks with a variable length between disk centers. Analyzing the trends in the\nshape of second maximum of the radial distribution function of the planar\nhard-dumbbell fluid it has been found that the type of transition could be\nsensitive to the length of hard-dumbbell molecules. From the ${NpT}$ Monte\nCarlo simulations data we show that if a hard-dumbbell length does not exceed\n15% of the disk diameter, the fluid-to-solid transition scenario follows the\ncase of a hard-disk fluid, i.e., the isotropic hard-dumbbell fluid experiences\nfreezing. However, for a hard-dumbbell length larger than 15% of disk diameter,\nthere is evidence that fluid-to-solid transition may change to continuous\ntransition, i.e., such an isotropic hard-dumbbell fluid will avoid freezing."
    },
    {
        "anchor": "Is there a reentrant glass in binary mixtures?: By employing computer simulations for a model binary mixture, we show that a\nreentrant glass transition upon adding a second component only occurs if the\nratio $\\alpha$ of the short-time mobilities between the glass-forming component\nand the additive is sufficiently small. For $\\alpha \\approx 1$, there is no\nreentrant glass, even if the size asymmetry between the two components is\nlarge, in accordance with two-component mode coupling theory. For $\\alpha \\ll\n1$, on the other hand, the reentrant glass is observed and reproduced only by\nan effective one-component mode coupling theory.",
        "positive": "Cellular solid behaviour of liquid crystal colloids. 2. Mechanical\n  properties: This paper presents the results of a rheological study of thermotropic\nnematic colloids aggregated into cellular structures. Small sterically\nstabilised PMMA particles dispersed in a liquid crystal matrix densely pack on\ncell interfaces, but reversibly mix with the matrix when the system is heated\nabove Tni. We obtain a remarkably high elastic modulus, G'~10^5 Pa, which is a\nnearly linear function of particle concentration. A characteristic yield stress\nis required to disrupt the continuity of cellular structure and liquify the\nresponse. The colloid aggregation in a ``poor nematic'' MBBA has the same\ncellular morphology as in the ``good nematic'' 5CB, but the elastic strength is\nat least an order of magnitude lower. These findings are supported by\ntheoretical arguments based on the high surface tension interfaces of a\nfoam-like cellular system, taking into account the local melting of nematic\nliquid and the depletion locking of packed particles on interfaces."
    },
    {
        "anchor": "A decatungstate-based Ionic liquid exhibiting very low dielectric\n  constant suitable for acting as solvent and catalyst for oxidation of organic\n  substrates: In this contribution, a new POM-based ionic liquid, namely\n(P6,6,6,14)4[W10O32], was fully characterized. Its viscosity and its very low\ndielectric constant make this hybrid ionic liquid suitable to be used as\nsolvent for organic transformations. As proof of concept, this unique ionic\nliquid combining solvant and catalyst properties was tested for catalytic\noxidation of various alcohols and alkenes in presence of H2O2",
        "positive": "Turn towards the crowd: A type of polar self-propelled particle generates a torque that makes it\nnaturally drawn to higher-density areas. The collective behaviour this induces\nin assemblies of particles constitutes a new form of phase separation in active\nfluids."
    },
    {
        "anchor": "Force networks and jamming in shear deformed sphere packings: The formation of self-organised structures that resist shear deformation have\nbeen discussed in the context of shear jamming and thickening[1-3], with\nfrictional forces playing a key role. However, shear induces geometric features\nnecessary for jamming even in frictionless packings[4]. We analyse conditions\nfor jamming in such assemblies by solving force and torque balance conditions\nfor their contact geometry. We demonstrate, and validate with frictional\nsimulations, that the isostatic condition for mean contact number Z = D + 1\n(for spatial dimension D = 2, 3) holds at jamming for both finite and infinite\nfriction, above the random loose packing density. We show that the shear\njamming threshold satisfies the marginal stability condition recently proposed\nfor jamming in frictionless systems[5]. We perform rigidity percolation\nanalysis[6,7] for D = 2 and find that rigidity percolation precedes shear\njamming, which however coincides with the percolation of over-constrained\nregions, leading to the identification of an intermediate phase analogous to\nthat observed in covalent glasses[8].",
        "positive": "A lattice-Boltzmann model for interacting amphiphilic fluids: We develop our recently proposed lattice-Boltzmann method for the\nnon-equilibrium dynamics of amphiphilic fluids (Chen, Boghosian, Coveney and\nNekovee, Proc. Roy. Soc. London A, 456, 1431 (2000).) Our method maintains an\norientational degree of freedom for the amphiphilic species and models fluid\ninteractions at a microscopic level by introducing self-consistent mean-field\nforces between the particles into the lattice-Boltzmann dynamics, in a way that\nis consistent with kinetic theory. We present the results of extensive\nsimulations in two dimensions which demonstrate the ability of our model to\ncapture the correct phenomenology of binary and ternary amphiphilic fluids."
    },
    {
        "anchor": "Shear-Driven Flow of Athermal, Frictionless, Spherocylinder Suspensions\n  in Two Dimensions: Particle Rotations and Orientational Ordering: We use numerical simulations to study the flow of a bidisperse mixture of\nathermal, frictionless, soft-core two dimensional spherocylinders driven by a\nuniform steady-state simple shear applied at a fixed volume and a fixed finite\nstrain rate $\\dot\\gamma$. Energy dissipation is via a viscous drag with respect\nto a uniformly sheared host fluid, giving a simple model for flow in a\nnon-Brownian suspension with Newtonian rheology. Considering a range of packing\nfractions $\\phi$ and particle asphericities $\\alpha$ at small $\\dot\\gamma$, we\nstudy the angular rotation $\\dot\\theta_i$ and the nematic orientational\nordering $\\mathbf{S}_2$ of the particles induced by the shear flow, finding a\nnon-monotonic behavior as the packing $\\phi$ is varied. We interpret this\nnon-monotonic behavior as a crossover from a small $\\phi$ region where\nsingle-particle-like behavior occurs, to a large $\\phi$ region where the\ngeometry of the dense packing dominates, the reduced free volume inhibits\nmotion, and a random Poisson-like process for particle rotations results. We\nalso argue that the finite nematic ordering $\\mathbf{S}_2$ is a consequence of\nthe shearing serving as an ordering field, rather than a result of long-ranged\ncooperative behavior among the particles. We arrive at these conclusions by\nconsideration of (i) the distribution of waiting times for a particle to rotate\nby $\\pi$, (ii) the behavior of the system under pure, as compared to simple,\nshearing, (iii) the relaxation of the nematic order parameter $\\mathbf{S}_2$\nwhen perturbed away from the steady state, and (iv) by construction a numerical\nmean-field model for the rotational motion of a particle. Our results also help\nto explain the singular behavior observed when taking the $\\alpha\\to 0$ limit\napproaching circular disks.",
        "positive": "A framework for modeling cells spreading, motility and the relocation of\n  proteins on advecting lipid membranes: The response of cells during spreading and motility is dictated by several\nmulti-physics events, which are triggered by extracellular cues and occur at\ndifferent time-scales. For this sake, it is not completely appropriate to\nprovide a cell with classical notions of the mechanics of materials, as for\n\"rheology\" or \"mechanical response\". Rather, a cell is an alive system with\nconstituents that show a reproducible response, as for the {\\em{contractility}}\nfor single stress fibers or for the mechanical response of a biopolymer actin\nnetwork, but that reorganize in response to external cues in a\nnon-exactly-predictable and reproducible way. Aware of such complexity, in this\nnote we aim at formulating a multi-physics framework for modeling cells\nspreading and motility, accounting for the relocation of proteins on advecting\nlipid membranes."
    },
    {
        "anchor": "Pair dynamics of active force dipoles in an odd-viscous fluid: We discuss the lateral dynamics of two active force dipoles, which interact\nwith each other via hydrodynamic interactions in a thin fluid layer that is\nactive and chiral. The fluid layer is modeled as a two-dimensional (2D)\ncompressible fluid with an odd viscosity, while the force dipole (representing\nan active protein or enzyme) induces a dipolar flow. Taking into account the\nmomentum decay in the 2D fluid, we obtain analytically the mobility tensor that\ndepends on the odd viscosity and includes nonreciprocal hydrodynamic\ninteractions. We find that the particle pair shows spiral behavior due to the\ntransverse flow induced by the odd viscosity. When the magnitude of the odd\nviscosity is large as compared with the shear viscosity, two types of\noscillatory behaviors are seen. One of them can be understood as arising from\nclosed orbits in dynamical systems, and its circular trajectories are\ndetermined by the ratio between the magnitude of the odd viscosity and the\nforce dipole. In addition, the phase diagrams of the particle dipolar angles\nare obtained numerically. Our findings reveal that the nonreciprocal response\nleads to complex dynamics of active particles embedded in an active fluid with\nodd viscosity.",
        "positive": "Connection between dynamics and thermodynamics of liquids on the melting\n  line: The dynamics of a large number of liquids and polymers exhibit scaling\nproperties characteristic of a simple repulsive inverse power law (IPL)\npotential, most notably the superpositioning of relaxation data as a function\nof the variable TV{\\gamma}, where T is temperature, V the specific volume, and\n{\\gamma} a material constant. A related scaling law, TmVm{\\Gamma}, with the\nsame exponent {\\Gamma}={\\gamma}, links the melting temperature Tm and volume Vm\nof the model IPL liquid; liquid dynamics is then invariant at the melting\npoint. Motivated by a similar invariance of dynamics experimentally observed at\ntransitions of liquid crystals, we determine dynamic and melting point scaling\nexponents {\\gamma} and {\\Gamma} for a large number of non-associating liquids.\nRigid, spherical molecules containing no polar bonds have {\\Gamma}={\\gamma};\nconsequently, the reduced relaxation time, viscosity and diffusion coefficient\nare each constant along the melting line. For other liquids {\\gamma}>{\\Gamma}\nalways; i.e., the dynamics is more sensitive to volume than is the melting\npoint, and for these liquids the dynamics at the melting point slows down with\nincreasing Tm (that is, increasing pressure)."
    },
    {
        "anchor": "Brittle to ductile transitions in glasses: Roles of soft defects and\n  loading geometry: Understanding the fracture toughness of glasses is of prime importance for\nscience and technology. We study it here using extensive atomistic simulations\nin which the interaction potential, glass transition cooling rate and loading\ngeometry are systematically varied, mimicking a broad range of experimentally\naccessible properties. Glasses' nonequilibrium mechanical disorder is\nquantified through $A_{\\rm g}$, the dimensionless prefactor of the universal\nspectrum of nonphononic excitations, which measures the abundance of soft\nglassy defects that affect plastic deformability. We show that while a\nbrittle-to-ductile transition might be induced by reducing the cooling rate,\nleading to a reduction in $A_{\\rm g}$, iso-$\\!A_{\\rm g}$ glasses are either\nbrittle or ductile depending on the degree of Poisson contraction under\nunconstrained uniaxial tension. Eliminating Poisson contraction using\nconstrained tension reveals that iso-$\\!A_{\\rm g}$ glasses feature similar\ntoughness, and that varying $A_{\\rm g}$ under these conditions results in\nsignificant toughness variation. Our results highlight the roles played by both\nsoft defects and loading geometry (which affects the activation of defects) in\nthe toughness of glasses.",
        "positive": "Flexoelectric switching in cholesteric blue phases: We present computer simulations of the response of a flexoelectric blue phase\nnetwork, either in bulk or under confinement, to an applied field. We find a\ntransition in the bulk between the blue phase I disclination network and a\nparallel array of disclinations along the direction of the applied field. Upon\nswitching off the field, the system is unable to reconstruct the original blue\nphase but gets stuck in a metastable phase. Blue phase II is comparatively much\nless affected by the field. In confined samples, the anchoring at the walls and\nthe geometry of the device lead to the stabilisation of further structures,\nincluding field-aligned disclination loops, splayed nematic patterns, and yet\nmore metastable states. Our results are relevant to the understanding of the\nswitching dynamics for a class of new, \"superstable\", blue phases which are\ncomposed of bimesogenic liquid crystals, as these materials combine anomalously\nlarge flexoelectric coefficients, and low or near-zero dielectric anisotropy."
    },
    {
        "anchor": "Instability and spatiotemporal rheochaos in a shear-thickening fluid\n  model: We model a shear-thickening fluid that combines a tendency to form\ninhomogeneous, shear-banded flows with a slow relaxational dynamics for fluid\nmicrostructure. The interplay between these factors gives rich dynamics, with\nperiodic regimes (oscillating bands, travelling bands, and more complex\noscillations) and spatiotemporal rheochaos. These phenomena, arising from\nconstitutive nonlinearity not inertia, can occur even when the steady-state\nflow curve is monotonic. Our model also shows rheochaos in a low-dimensional\ntruncation where sharply defined shear bands cannot form.",
        "positive": "Mono-to-multilayer transition in growing bacterial colonies: The transition from monolayers to multilayered structures in bacterial\ncolonies is a fundamental step in biofilm development. Observed across\ndifferent morphotypes and species, this transition is triggered within freely\ngrowing bacterial microcolonies comprising a few hundred cells. Using a\ncombination of numerical simulations and analytical modeling, here we\ndemonstrate that this transition originates from the competition between\ngrowth-induced in-plane active stresses and vertical restoring forces, due to\nthe cell-substrate interactions. Using a simple chainlike colony of laterally\nconfined cells, we show that the transition sets when individual cells become\nunstable to rotations, thus it is localized and mechanically deterministic.\nAsynchronous cell division renders the process stochastic, so that all the\ncritical parameters that control the onset of the transition are continuously\ndistributed random variables. Here we demonstrate that the occurrence of the\nfirst division in the colony can be approximated as a Poisson process in the\nlimit of large cells numbers. This allows us to approximately calculate the\nprobability distribution function of the position and time associated with the\nfirst extrusion. The rate of such a Poisson process can be identified as the\norder parameter of the transition, thus highlighting its mixed\ndeterministic-stochastic nature."
    },
    {
        "anchor": "Statistical modeling of equilibrium phase transition in confined fluids: The phase transition of confined fluids in mesoporous materials deviates from\nthat of bulk fluids due to the interactions with the surrounding heterogeneous\nstructure. For example, adsorbed fluids in metal-organic-frameworks (MOFs) have\natypical phase characteristics such as capillary condensation and higher-order\nphase transitions due to a strong heterogeneous field. Considering a many-body\nproblem in the presence of a nonuniform external field, we model the host-guest\nand guest-guest interactions in MOFs. To solve the three-dimensional Ising\nmodel, we use the mean-field theory to approximate the guest-guest interactions\nand Mayer's f-functions to describe the host-guest interactions in a unit cell.\nLater, using Hill's theory of nanothermodynamics, we define differential\nthermodynamic functions to understand the distribution of intensive properties\nand integral thermodynamic functions to explain the phase transition in\nconfined fluids. The investigation reveals a distinct behavior where fluids\nconfined in larger pores undergo a discontinuous (first-order) phase\ntransition, whereas those confined in smaller pores experience a continuous\n(higher-order) phase transition. Furthermore, the results indicate that the\nfree-energy barrier for phase transitions is lower in confined fluids than in\nbulk fluids giving rise to a lower condensation pressure relative to the bulk\nsaturation pressure. Finally, the integral thermodynamic functions are\nsuccinctly presented in the form of a phase diagram, marking an initial step\ntoward a more practical approach for understanding the phase behavior of\nconfined fluids.",
        "positive": "Modulated nematic structures and chiral symmetry breaking in 2D: We have studied the properties of biaxial particles interacting via an\nanisotropic pair potential, involving second rank quadrupolar and third rank\noctupolar coupling terms, using Monte Carlo simulation. The particles occupy\nthe sites of a 2D square lattice and the interactions are restricted to nearest\nneighbours. The system exhibits spontaneous chiral symmetry breaking from an\nisotropic phase to a chiral modulated nematic phase, composed of ambidextrous\nchiral domains. When two-fold axes of quadrupolar and octupolar tensors\ncoincide this modulated phase appears to be the ambidextrous cholesteric phase\nof pitch comparable with a few lattice spacings, which can be regarded as a\nlimiting case of the nematic twist bend phase. The associated phase transition\nis first-order."
    },
    {
        "anchor": "Chain stiffness bridges conventional polymer and bio-molecular phases}: Chain molecules play important roles in industry and in living cells. Our\nfocus here is on distinct ways of modeling the stiffness inherent in a chain\nmolecule. We consider three types of stiffnesses -- one yielding an energy\npenalty for local bends (energetic stiffness) and the other two forbidding\ncertain classes of chain conformations (entropic stiffness). Using detailed\nWang-Landau microcanonical Monte Carlo simulations, we study the interplay\nbetween the nature of the stiffness and the ground state conformation of a\nself-attracting chain. We find a wide range of ground state conformations\nincluding a coil, a globule, a toroid, rods, helices, zig-zag strands\nresembling $\\beta$-sheets, as well as knotted conformations allowing us to\nbridge conventional polymer phases and biomolecular phases. An analytical\nmapping is derived between the persistence lengths stemming from energetic and\nentropic stiffness. Our study shows unambiguously that different stiffness play\ndifferent physical roles and have very distinct effects on the nature of the\nground state of the conformation of a chain, even if they lead to identical\npersistence lengths.",
        "positive": "Homogeneous ice nucleation at moderate supercooling from molecular\n  simulation: Among all the freezing transitions, that of water into ice is probably the\nmost relevant to biology, physics, geology or atmospheric science. In this work\nwe investigate homogeneous ice nucleation by means of computer simulations. We\nevaluate the size of the critical cluster and the nucleation rate for\ntemperatures ranging between 15K and 35K below melting. We use the TIP4P/2005\nand the TIP4P/Ice water models. Both give similar results when compared at the\nsame temperature difference with the model's melting temperature. The size of\nthe critical cluster varies from $\\sim$8000 molecules (radius$ = 4$nm) at 15K\nbelow melting to $\\sim$600 molecules (radius$ = 1.7$nm) at 35K below melting.\nWe use Classical Nucleation Theory (CNT) to estimate the ice-water interfacial\nfree energy and the nucleation free energy barrier. We obtain an interfacial\nfree energy of 29(3)mN/m from an extrapolation of our results to the melting\ntemperature. This value is in good agreement both with experimental\nmeasurements and with previous estimates from computer simulations of\nTIP4P-like models. Moreover, we obtain estimates of the nucleation rate from\nsimulations of the critical cluster at the barrier top. The values we get for\nboth models agree within statistical error with experimental measurements. At\ntemperatures higher than 20K below melting we get nucleation rates slower than\nthe appearance of a critical cluster in all the water of the hydrosphere in the\nage of the universe. Therefore, our simulations predict that water freezing\nabove this temperature must necessarily be heterogeneous."
    },
    {
        "anchor": "Topological transitions, turbulent-like motion and long-time-tails\n  driven by cell division in biological tissues: The complex spatiotemporal flow patterns in living tissues, driven by active\nforces, have many of the characteristics associated with inertial turbulence\neven though the Reynolds number is extremely low. Analyses of experimental data\nfrom two-dimensional epithelial monolayers in combination with agent-based\nsimulations show that cell division and apoptosis lead to directed cell motion\nfor hours, resulting in rapid topological transitions in neighboring cells.\nThese transitions in turn generate both long ranged and long lived clockwise\nand anticlockwise vortices, which gives rise to turbulent-like flows. Both\nexperiments and simulations show that at long wavelengths the wave vector ($k$)\ndependent energy spectrum $E(k) \\approx k^{-5/3}$, coinciding with the\nKolmogorov scaling in fully developed inertial turbulence. Using theoretical\narguments and simulations, we show that long-lived vortices lead to long-time\ntails in the velocity auto-correlation function, $C_v(t) \\sim t^{-1/2}$, which\nhas the same structure as in classical 2D fluids but with a different scaling\nexponent.",
        "positive": "Active elastocapillarity in soft solids with negative surface tension: Active solids consume energy to allow for actuation, shape change, and wave\npropagation not possible in equilibrium. Whereas active interfaces have been\nrealized across many experimental systems, control of three-dimensional (3D)\nbulk materials remains a challenge. Here, we develop continuum theory and\nmicroscopic simulations that describe a 3D soft solid whose boundary\nexperiences active surface stresses. The competition between active boundary\nand elastic bulk yields a broad range of previously unexplored phenomena, which\nare demonstrations of so-called active elastocapillarity. In contrast to thin\nshells and vesicles, we discover that bulk 3D elasticity controls snap-through\ntransitions between different anisotropic shapes. These transitions meet at a\ncritical point, allowing a universal classification via Landau theory. The\nactive surface modifies elastic wave propagation to allow zero, or even\nnegative, group velocities. These phenomena offer robust principles for\nprogramming shape change and functionality into active solids, from robotic\nmetamaterials down to shape-shifting nanoparticles."
    },
    {
        "anchor": "The absence of crystallization on supercooling in a single component\n  system of particles interacting through the harmonic-repulsive potential. A\n  possible formation of a quasicrystal at a different value of the density: In this note, we report about two, as it seems to us, rather unusual\nobservations made in molecular dynamics simulations of the single component\nsystems of particles interacting through the harmonic-repulsive pair potential\nin 3D. In particular, at some densities, we observed deeply supercooled liquid\nstates which did not exhibit crystallization in rather long MD runs. This\nobservation is unusual because usually liquids formed by particles of only one\ntype rather readily crystallize on supercooling. At a different value of the\ndensity we observed crystallization of the liquid into a state formed by chains\n(or lines) of particles which organize themselves into columns in such a way\nthat each column is formed by seven lines of particles. Alternatively, one can\nthink that each such column is formed by three alternating helical coils. In\nour view, it is possible that the overall structure that crystallizes from the\nliquid at this density is quasicrystalline. If it is indeed the case, then this\nobservation is unusual because, as far as we understand, it is not expected, at\npresent, that quasicrystalline structures can form in such a simple potential\nas harmonic-repulsive potential. Investigations related to the presumable phase\ndiagram of the particles interacting through the harmonic-repulsive potential\nhave been reported in [J. Chem. Phys. {\\bf 134}, 044903 (2011)]. Our results\nappear to be at odds with some of the results presented there.",
        "positive": "Dependence of folding rates on protein length: Using three-dimensional Go lattice models with side chains for proteins, we\ninvestigate the dependence of folding times on protein length. In agreement\nwith previous theoretical predictions, we find that the folding time grows as a\npower law with the chain length N with exponent $\\lambda \\approx 3.6$ for the\nGo model, in which all native interactions (i.e., between all side chains and\nbackbone atoms) are uniform. If the interactions between side chains are given\nby pairwise statistical potentials, which introduce heterogeneity in the\ncontact energies, then the power law fits yield large $\\lambda$ values that\ntypically signifies a crossover to an underlying activated process.\nAccordingly, the dependence of folding time is best described by the stretched\nexponential \\exp(\\sqrt{N}). The study also shows that the incorporation of side\nchains considerably slows down folding by introducing energetic and topological\nfrustration."
    },
    {
        "anchor": "Ab initio molecular and solid state studies of Fe$^{II}$ spin cross-over\n  system [Fe(btz)$_2$(NCS)$_2$: Ab initio computations within the density functional theory are reported for\nthe spin cross-over complex, [Fe(btz)$_{2}$(NCS)$_{2}$], where 3d$^6$ Fe$^{II}$\nis characterized by High Spin (HS t$_{2g}^4$, e$_g^2$) and Low Spin (LS\nt$_{2g}^6$, e$_g^0$) states. Results of infra red and Raman spectra for the\nisolated molecule are complemented for the crystalline solid with a full\naccount of the electronic band structure properties: the density of states\nassessing the crystal field effects and the chemical bonding assigning a\nspecific role to the Fe-N interaction within the coordination sphere of\nFe$^{II}$.",
        "positive": "Boundary element method for normal non-adhesive and adhesive contacts of\n  power-law graded elastic materials: Recently proposed formulation of the Boundary Element Method for adhesive\ncontacts has been generalized for contacts of functionally graded materials\nwith and without adhesion. First, proceeding from the fundamental solution for\nsingle force acting on the surface of a half space with a power-law varying\nelastic modulus, the deformation produced by constant pressure acting on a\nrectangular element was calculated and the influence matrix was obtained for a\nrectangular grid. The inverse problem for the calculation of required stress in\ncontact area from a known surface deformation was solved by use of\nconjugate-gradient technique. For the transformation between the stresses and\ndisplacements, the Fast Fourier Transformation is used which drastically\nreduces the computation time. For the adhesive contact of graded material, the\ndetachment criterion based on the method of Pohrt and Popov was proposed. A\nnumber of numerical test for the problem having exact analytical solution have\nbeen carried out confirming the correctness of underlying ideas and numerical\nimplementation."
    },
    {
        "anchor": "Surface and interfacial tensions of Hofmeister electrolytes: We present a theory that is able to account quantitatively for the surface\nand interfacial tensions of different electrolyte solutions. It is found that\nnear the interface, ions can be separated into two classes: the kosmotropes and\nthe chaotropes. While the kosmotropes remain hydrated near the interface and\nare repelled from it, the chaotropes loose their hydration sheath and become\nadsorbed to the surface. The anionic adsorption is strongly correlated with the\nJones-Dole viscosity B-coefficient. Both hydration and polarizability must be\ntaken into account to obtain a quantitative agreement with the experiments. To\ncalculate the excess interfacial tension of the oil-electrolyte interface, the\ndispersion interactions must also be included. The theory can also be used to\ncalculate the surface and the interfacial tensions of acid solutions,\npredicting a strong surface adsorption of hydronium ion.",
        "positive": "Phase Behaviors of Ionic Liquids Attributed to the Dual Ionic and\n  Organic Nature: Ionic liquids (ILs), also known as room-temperature molten salts, are\ncomposed of pure ions with melting points usually below 100 degrees centigrade.\nBecause of their low volatility and vast amounts of species, ILs can serve as\n\"green solvents\" and \"designer solvents\" to meet the requirements of various\napplications by fine tuning their molecular structures. A good understanding of\nthe phase behaviors of ILs is certainly fundamentally important in terms of\ntheir wide applications. This review intends to summarize the major conclusions\nso far drawn on phase behaviors of ILs by computational, theoretical, and\nexperimental studies, illustrating the intrinsic relationship between their\ndual ionic and organic nature and the crystalline phases, nanoscale segregation\nliquid phase, ionic liquid crystal phases, as well as phase behaviors of their\nmixture with small organic molecules."
    },
    {
        "anchor": "Discrimination of Chiral and Helical Contributions to Raman Scattering\n  of Liquid Crystals using Vortex Beams: We use vortex photon fields with orbital and spin angular momentum to probe\nchiral fluctuations within liquid crystals. In the regime of iridescence with a\nwell-defined pitch length of chirality, we find low energy Raman scattering\nthat can be decomposed into helical and chiral components depending on the\nscattering vector and the topological charge of the incident photon field.\nBased on the observation of an anomalous dispersion we attribute quasi-elastic\nscattering to a transfer of angular momenta to roton-like quasiparticles. The\nlatter are due to a competition of short-range repulsive and long-range dipolar\ninteractions. Our approach using a transfer of orbital angular momentum opens\nup an avenue for the advanced characterization of chiral and optically active\ndevices and materials.",
        "positive": "A theory for the flow of chemically-responsive polymer solutions:\n  equilibrium and shear-induced phase separation: Chemically-responsive polymers are macromolecules that respond to local\nvariations of the chemical composition of the solution by changing their\nconformation, with notable examples including polyelectrolytes, proteins and\nDNA. The polymer conformation changes can occur in response to changes to the\npH, the ionic strength or to the concentration of a generic solute that\ninteracts with the polymer. These chemical stimuli can lead to drastic\nvariations of the polymer flexibility and even trigger a transition from a coil\nto a globule polymer conformation. In many situations the spatial distribution\nof the chemical stimuli can be highly inhomogeneous, which can lead to large\nspatial variations of polymer conformation and of the rheological properties of\nthe mixture. In this paper, we develop a theory for the flow of a mixture of a\nsolute and chemically-responsive polymers. The approach is valid for generic\nflows and inhomogeneous distributions of polymers and solutes. To model the\npolymer conformation changes introduced by the interactions with the solute, we\nconsider the polymers as linear elastic dumbbells whose spring stiffness\ndepends on the solute concentration. We use the Onsager's variational formalism\nto derive the equations governing the evolution of the variables, which unveils\nnovel couplings between the distribution of dumbbells and that of the solute.\nFinally, we use a linear stability analysis to show that the governing\nequations predict an equilibrium phase separation and a distinct shear-induced\nphase separation whereby a homogeneous distribution of solute and dumbbells\nspontaneously demix. Similar phase transitions have been observed in previous\nexperiments using stimuli-responsive polymers and may play an important role in\nliving systems."
    },
    {
        "anchor": "Resistance of Josephson Junction Arrays at Low Temperatures: We study motion of vortices in arrays of Josephson junctions at zero\ntemperature where it is controlled by quantum tunneling from one plaquette to\nanother. The tunneling process is characterized by a finite time and can be\nslow compared to the superconducting gap (so that $\\tau \\Delta >> 1$). The\ndissipation which accompanies this process arises from rare processes when a\nvortex excites a quasiparticle above the gap while tunneling through a single\njunction. We find that the dissipation is significant even in the case $\\tau\n\\Delta >> 1$, in particular it is not exponentially small in this parameter. We\nuse the calculated energy dissipation for the single vortex jump to estimate\nthe physical resistance of the whole array.",
        "positive": "Exact calculation of the skyrmion lifetime in a ferromagnetic Bose\n  condensate: The tunneling rate of a skyrmion in ferromagnetic spin-1/2 Bose condensates\nthrough an off-centered potential barrier is calculated exactly with the\nperiodic instanton method. The prefactor is shown to depend on the chemical\npotential of the core atoms, at which level the atom tunnels. Our results can\nbe readily extended to estimate the lifetime of other topological excitations\nin the condensate, such as vortices and monopoles."
    },
    {
        "anchor": "Measuring local volume fraction, long-wavelength correlations and\n  fractionation in a phase-separating polydisperse fluid: We dynamically simulate fractionation (partitioning of particle species)\nduring spinodal gas-liquid separation of a size-polydisperse colloid, using\npolydispersity up to ~40% and a skewed parent size distribution. We introduce a\nnovel coarse-grained Voronoi method to minimise size bias in measuring local\nvolume fraction, along with a variety of spatial correlation functions which\ndetect fractionation without requiring a clear distinction between the phases.\nThese can be applied whether or not a system is phase separated, to determine\nstructural correlations in particle size, and generalise easily to other kinds\nof polydispersity (charge, shape, etc.). We measure fractionation in both mean\nsize and polydispersity between the phases, its direction differing between\nmodel interaction potentials which are identical in the monodisperse case.\nThese qualitative features are predicted by a perturbative theory requiring\nonly a monodisperse reference as input. The results show that intricate\nfractionation takes place almost from the start of phase separation, so can\nplay a role even in nonequilibrium arrested states. The methods for\ncharacterisation of inhomogeneous polydisperse systems could in principle be\napplied to experiment as well as modelling.",
        "positive": "Reply to comment on `Measurement of Effective Temperatures in an Aging\n  Colloidal Glass': Reply to comment by Jop et al. (arXiv:0705.1421v1)."
    },
    {
        "anchor": "Impact of extended long-range electrostatics on the correlation of\n  liquid-liquid equilibria in aqueous ionic liquid systems: Recently an improved long-range model for electrolyte solutions was developed\nthat is applicable from infinite dilution to pure salt. This paper tests this\nclaim for the first time applying it to the calculation of liquid-liquid\nequilibria for mixtures of different ionic liquids (ILs) and water. The\nconventional Pitzer-Debye-H\\\"uckel (PDH) equation is compared to two of its\nnew, thermodynamically consistent extensions. Both development stages, the\nextended PDH term and the modified-extended PDH, account for concentration\ndependent mixture properties instead of using solvent properties. The latter\none additionally introduces a modified parameter of closest approach which\nimproves the overall performance of the model for high electrolyte\nconcentrations in systems with variable or low permittivities. To account for\nthe short-range interactions, these long-range models are coupled with the\nUNIversal QUAsi-Chemical (UNIQUAC) model. Three modeling strategies were tested\nfor the short-range contribution. First, the UNIQUAC parameters were adjusted\nto each system individually, then the binary interaction parameters were the\nsame for each binary interaction type for all the systems and lastly a linear\nfunction of the carbon number was used where possible. For all systems and all\nmodeling strategies tested, the predictive performance increased from PDH to\nE-PDH and then to ME-PDH. Overall, an introduction of concentration dependent\nproperties and the modification added to ME-PDH enhanced modeling performance\nwhen describing these systems, showing the general applicability of this novel\nlong-range term.",
        "positive": "Phase-field-crystal models for condensed matter dynamics on atomic\n  length and diffusive time scales: an overview: Here, we review the basic concepts and applications of the\nphase-field-crystal (PFC) method, which is one of the latest simulation\nmethodologies in materials science for problems, where atomic- and microscales\nare tightly coupled. The PFC method operates on atomic length and diffusive\ntime scales, and thus constitutes a computationally efficient alternative to\nmolecular simulation methods. Its intense development in materials science\nstarted fairly recently following the work by Elder et al. [Phys. Rev. Lett. 88\n(2002), p. 245701]. Since these initial studies, dynamical density functional\ntheory and thermodynamic concepts have been linked to the PFC approach to serve\nas further theoretical fundaments for the latter. In this review, we summarize\nthese methodological development steps as well as the most important\napplications of the PFC method with a special focus on the interaction of\ndevelopment steps taken in hard and soft matter physics, respectively. Doing\nso, we hope to present today's state of the art in PFC modelling as well as the\npotential, which might still arise from this method in physics and materials\nscience in the nearby future."
    },
    {
        "anchor": "Structure, design and mechanics of a pop-up origami with cuts: Rotational erection system (RES) represents an origami-based design method\nfor generating a three-dimensional (3D) structure from a planar sheet without\ncompression. Its rotational and translational kinematics is fully encoded in a\nform of prescribed cuts and folds that has only zero degrees of freedom in the\ngeometric limit. Here we characterize mechanical and geometric properties of a\nthreefold symmetric RES by combining finite element numerical simulation and\nphysical experiment. We demonstrate that a plate bending in RES creates a\nphysical route connecting the two energetically separated configurations, i.e.,\nflat and standing states, allowing RES to morph into a 3D shape via a\nsnap-through transition. We quantify the energy barrier for the bistability and\nshow that it is independent of the entire span of the structure but depends\nonly on its aspect ratio, indicating that the bistability of RES is essentially\nscale independent. The scale-free and tunable nature of the emergent\nbistability will be potentially useful in a range of applications including\nswitching devices, energy-adsorbing mechanical systems, and one-step\nconstruction in architectures. The present study clarifies the basic actuation\nmechanism of an origami-based deployable structure extended with chiral\npatterned cuts, opening up the way for the use of optimally designed RES in a\nrange of man-made systems.",
        "positive": "On the contact values of the density profiles in an electric double\n  layer using density functional theory: A recently proposed local second contact value theorem [Henderson D., Boda\nD., J. Electroanal. Chem., 2005, 582, 16] for the charge profile of an electric\ndouble layer is used in conjunction with the existing Monte Carlo data from the\nliterature to assess the contact behavior of the electrode-ion distributions\npredicted by the density functional theory. The results for the contact values\nof the co- and counterion distributions and their product are obtained for the\nsymmetric valency, restricted primitive model planar double layer for a range\nof electrolyte concentrations and temperatures. Overall, the theoretical\nresults satisfy the second contact value theorem reasonably well, the agreement\nwith the simulations being semi-quantitative or better. The product of the co-\nand counterion contact values as a function of the electrode surface charge\ndensity is qualitative with the simulations with increasing deviations at\nhigher concentrations."
    },
    {
        "anchor": "Coulombic Surface-Ion Interactions Induce Nonlinear and\n  Chemistry-Specific Charging Kinetics: While important for many industrial applications, chemical reactions\nresponsible for charging of solids in water are often poorly understood. We\ntheoretically investigate the charging kinetics of solid-liquid interfaces, and\nfind that the time-dependent equilibration of surface charge contains key\ninformation not only on the reaction mechanism, but also on the valency of the\nreacting ions. We construct a non-linear differential equation describing\nsurface charging by combining chemical Langmuir kinetics and electrostatic\nPoisson-Boltzmann theory. Our results reveal a clear distinction between\nlate-time (near-equilibrium) and short-time (far-from-equilibrium) relaxation\nrates, the ratio of which contains information on the charge valency and ad- or\ndesorption mechanism of the charging process. Similarly, we find that\nsingle-ion reactions can be distinguished from two-ion reactions as the latter\nshow an inflection point during equilibration. Interestingly, such inflection\npoints are characteristic of autocatalytic reactions, and we conclude that the\nCoulombic ion-surface interaction is an autocatalytic feedback mechanism.",
        "positive": "A kinetic perspective of charge transfer reactions: the downfall of\n  hard/soft acid/base interactions: We show how to incorporate the possibility of kinetic control in the\nconceptual Density Functional Theory formalism. This allow us to prove that the\nhard/soft acid/base principle will likely fail when the reactions are not\nthermodynamically-driven."
    },
    {
        "anchor": "Interplay between self-assembly and phase separation in a\n  polymer-complex model: We present a theoretical model for predicting the phase behavior of polymer\nsolutions in which phase separation competes with oligomerization.\nSpecifically, we consider scenarios in which the assembly of polymer chains\ninto stoichiometric complexes prevents the chains from phase-separating via\nattractive polymer-polymer interactions. Combining statistical associating\nfluid theory with a two-state description of self-assembly, we find that this\nmodel exhibits rich phase behavior, including re-entrance, and we show how\nsystem-specific phase diagrams can be derived graphically. Importantly, we\ndiscuss why these phase diagrams can resemble -- and yet are qualitatively\ndistinct from -- phase diagrams of polymer solutions with lower critical\nsolution temperatures.",
        "positive": "Hydrogel sphere impact cratering, spreading and bouncing on granular\n  media: The impact of a hydrogel sphere onto a granular target results in both the\ndeformation of the sphere and the formation of a prominent topographic feature\nknown as impact crater on the granular surface. We investigate the crater\nformation and scaling, together with the spreading diameter and post-impact\ndynamics of the spheres by performing a series of experiments, varying the\nYoung's modulus $Y$ and impact speed $U_{0}$ of the hydrogel spheres, and the\npacking fraction and grain size of the granular target. We determine how the\ncrater diameter and depth depend on $Y$ and find the data to be consistent with\nthose from earlier experiments using droplets and hard spheres. Most\nspecifically, we find that the crater diameter data are consistent with a power\nlaw, where the power exponent changes more sharply when $Y$ becomes less than\n$200$ Pa. Next, we introduce an estimate for the portion of the impact kinetic\nenergy that is stored in elastic energy during impact, and thus correct the\nenergy that remains available for crater formation. Subsequently, we determine\nthe deformation of the hydrogel sphere and find that the normalized spreading\ndiameter data are well collapsed introducing an equivalent velocity from an\nenergy balance of the the initial kinetic energy against surface and elastic\nenergy. Finally, we observe that under certain intermediate values for the\nYoung's modulus and impact velocities, the particles rebound from the impact\ncrater. We determine the phase diagram and explain our findings from a\ncomparison of the elastocapillary spreading time and the impact duration."
    },
    {
        "anchor": "Adsorption of polyelectrolytes on charged microscopically patterned\n  surfaces: In the present study, we have investigated, using Monte Carlo simulations\n(MC), the adsorption of polyelectrolytes on the charged nanopatterned surfaces.\nDifferent surface patterns were considered and we noticed that the amount of\nadsorption is directly dependent on the size of the domains. Also in the case\nof checkerboard configuration, it was observed that the polyelectrolytes are\naligned along the diagonal of square domains.",
        "positive": "Domain Walls and Anchoring Transitions Mimicking Nematic Biaxiality in\n  the Oxadiazole Bent-Core Liquid Crystal C7: We investigate the origin of secondary disclinations that were recently\ndescribed as a new evidence of a biaxial nematic phase in an oxadiazole\nbent-core thermotropic liquid crystal C7. With an assortment of optical\ntechniques such as polarizing optical microscopy, LC PolScope, and fluorescence\nconfocal polarizing microscopy, we demonstrate that the secondary disclinations\nrepresent non-singular domain walls formed in an uniaxial nematic during the\nsurface anchoring transition, in which surface orientation of the director\nchanges from tangential (parallel to the bounding plates) to tilted. Each\ndomain wall separates two regions with the director tilted in opposite\nazimuthal directions. At the centre of the wall, the director remains parallel\nto the bonding plates. The domain walls can be easily removed by applying a\nmodest electric field. The anchoring transition is explained by the balance of\n(a) the intrinsic perpendicular surface anchoring produced by the polyimide\naligning layer and (b) tangential alignment caused by ionic impurities forming\nelectric double layers. The model is supported by the fact that the temperature\nof the tangential-tilted anchoring transition decreases as the cell thickness\nincreases and as the concentration of ionic species (added salt) increases. We\nalso demonstrate that the surface alignment is strongly affected by thermal\ndegradation of the samples. The study shows that C7 exhibits only a uniaxial\nnematic phase and demonstrate yet another mechanism (formation of secondary\ndisclinations) by which a uniaxial nematic can mimic a biaxial nematic\nbehaviour."
    },
    {
        "anchor": "Fragility and hysteretic creep in frictional granular jamming: The granular jamming transition is experimentally investigated in a\ntwo-dimensional system of frictional, bi-dispersed disks subject to\nquasi-static, uniaxial compression at zero granular temperature. Currently\naccepted results show the jamming transition occurs at a critical packing\nfraction $\\phi_c$. In contrast, we observe the first compression cycle exhibits\n{\\it fragility} - metastable configuration with simultaneous jammed and\nun-jammed clusters - over a small interval in packing fraction ($\\phi_1 < \\phi\n< \\phi_2$). The fragile state separates the two conditions that define $\\phi_c$\nwith an exponential rise in pressure starting at $\\phi_1$ and an exponential\nfall in disk displacements ending at $\\phi_2$. The results are explained\nthrough a percolation mechanism of stressed contacts where cluster growth\nexhibits strong spatial correlation with disk displacements. Measurements with\nseveral disk materials of varying elastic moduli $E$ and friction coefficients\n$\\mu$, show friction directly controls the start of the fragile state, but\nindirectly controls the exponential slope. Additionally, we experimentally\nconfirm recent predictions relating the dependence of $\\phi_c$ on $\\mu$. Under\nrepetitive loading (compression), the system exhibits hysteresis in pressure,\nand the onset $\\phi_c$ increases slowly with repetition number. This friction\ninduced hysteretic creep is interpreted as the granular pack's evolution from a\nmetastable to an eventual structurally stable configuration. It is shown to\ndepend upon the quasi-static step size $\\Delta \\phi$ which provides the only\nperturbative mechanism in the experimental protocol, and the friction\ncoefficient $\\mu$ which acts to stabilize the pack.",
        "positive": "A First Passage Time Analysis of Atomic-Resolution Simulations of the\n  Ionic Transport in a Bacterial Porin: We have studied the dynamics of chloride and potassium ions in the interior\nof the OmpF porin under the influence of an external electric field. From the\nresults of extensive all-atom molecular dynamics simulations of the system we\ncomputed several first passage time (FPT) quantities to characterize the\ndynamics of the ions in the interior of the channel. Such FPT quantities\nobtained from MD simulations demonstrate that it is not possible to describe\nthe dynamics of chloride and potassium ions inside the whole channel with a\nsingle constant diffusion coefficient. However, we showed that a valid,\nstatistically rigorous, description in terms of a constant diffusion\ncoefficient D and an effective deterministic force Feff can be obtained after\nappropriate subdivison of the channel in different regions suggested by the\nX-ray structure. These results have important implications for popular\nsimplified descriptions of channels based on the 1D Poisson-Nernst-Planck (PNP)\nequations. Also, the effect of entropic barriers on the diffusion of the ions\nis identified and briefly discussed."
    },
    {
        "anchor": "Integrated nanoextraction and colorimetric reactions in surface\n  nanodroplets for combinative analysis: A combinative approach for chemical analysis makes it possible to distinguish\na mixture of a large number of compounds from other mixtures in a single step.\nThis work demonstrates a combinative analysis approach by using surface\nnanodroplets for integrating nanoextraction and colorimetric reactions for the\nidentification of multi-component mixtures. The model analytes are acidic\ncompounds dissolved in oil that are extracted into aqueous droplets on a solid\nsubstrate. The proton from acid dissociation reacts with the halochromic\nchemical compounds inside the droplets, leading to the color change of the\ndroplets. The rate of the colorimetric reaction exhibits certain specificity\nfor the acid type, distinguishing acid mixtures with the same pH value. The\nunderlying principle is that the acid transport rate is associated with the\npartition coefficient and the dissociation constant of the acid, in addition to\nthe concentration in oil. As a demonstration, we showed that droplet-based\ncombinative analysis can be applied for anti-counterfeiting of various\nalcoholic spirits by comparing decolor time of organic acid mixtures in the\nspirits. The readout can be done by using a common hand-hold mobile phone.",
        "positive": "Development of Statistical Associating Fluid Theory for Aqueous Ionic\n  Liquid Solutions by Implementing Monte Carlo Simulations and Ornstein-Zernike\n  Integral Equation: A recent version of statistical associating fluid theory (SAFT), namely\nSAFT2, is coupled with the van der Waals and Platteeuw theory to study the\nalkane hydrate phase equilibrium conditions. The model is found to provide an\naccurate representation of the alkane hydrate dissociation conditions with and\nwithout inhibitors, such as salts, alcohols, as well as mixed salts and\nalcohol. Based on SAFT2, a heterosegmented SAFT equation of state is developed\nto model the thermodynamic properties of aqueous ionic liquid (IL) solutions,\nwhich is recently discovered as dual function gas hydrate inhibitors. With\ntransferrable model parameters, the heterosegmented SAFT generally well\nrepresents the liquid density, activity coefficient, and osmotic coefficient of\naqueous imidazolium IL solutions. The inhibition effects of imidazolium IL on\nmethane hydrate is also studied by the heterosegmented SAFT and the van der\nWaals and Platteeuw theory.\n  The heterosegmented SAFT is then modified to better represent the\nthermodynamic properties of aqueous IL solutions with the help of Monte Carlo\nsimulation and the solutions of Ornstein-Zernike integral equation. A simple\nmodification of MSA, referred to as KMSA, is proposed to accurately predict the\nexcess energies of electrolyte system in mixture with neutral component. Monte\nCarlo simulations are also conducted on flexible charged hard-sphere chain\nmolecules, and a SAFT model which implements either a dimer or a dimer-monomer\napproach to account for the charged chain connectivity is proposed."
    },
    {
        "anchor": "Higher-order glass-transition singularities in systems with short-ranged\n  attractive potentials: Within the mode-coupling theory for the evolution of structural relaxation,\nthe A_4 glass-transition singularities are identified for systems of particles\ninteracting with a hard-sphere repulsion complemented by different short-ranged\npotentials: Baxter's singular potential regularized by a large-wave-vector\ncutoff, a model for the Asakura-Oosawa depletion attraction, a triangular\npotential, a Yukawa attraction, and a square-well potential. The regular\npotentials yield critical packing fractions, critical Debye-Waller factors and\ncritical amplitudes very close to each other. The elastic moduli and the\nparticle's localization lengths for corresponding states of the Yukawa system\nand the square-well system may differ by up to 20% and 10%, respectively.",
        "positive": "Predicting the structural colors of films of disordered photonic balls: Photonic balls are spheres tens of micrometers in diameter containing\nassemblies of nanoparticles or nanopores with a spacing comparable to the\nwavelength of light. When these nanoscale features are disordered, but still\ncorrelated, the photonic balls can show structural color with low\nangle-dependence. Their colors, combined with the ability to add them to a\nliquid formulation, make photonic balls a promising new type of pigment\nparticle for paints, coatings, and other applications. However, it is\nchallenging to predict the color of materials made from photonic balls, because\nthe sphere geometry and multiple scattering must be accounted for. To address\nthese challenges, we develop a multiscale modeling approach involving Monte\nCarlo simulations of multiple scattering at two different scales: we simulate\nmultiple scattering and absorption within a photonic ball and then use the\nresults to simulate multiple scattering and absorption in a film of photonic\nballs. After validating against experimental spectra, we use the model to show\nthat films of photonic balls scatter light in fundamentally different ways than\ndo homogeneous films of nanopores or nanoparticles, because of their increased\nsurface area and refraction at the interfaces of the balls. Both effects tend\nto sharply reduce color saturation relative to a homogeneous nanostructured\nfilm. We show that saturated colors can be achieved by placing an absorber\ndirectly in the photonic balls and mitigating surface roughness. With these\ndesign rules, we show that photonic-ball films have an advantage over\nhomogeneous nanostructured films: their colors are even less dependent on the\nangle."
    },
    {
        "anchor": "Investigation of the influence of temperature on the conductive\n  properties of copolymer PVC -PolyAcetylene films: The temperature dependence of conductivity of partially dehydrochlorinated\nPVC films, containing in their macromolecules chains of polyene-conjugated\nbonds (PCB) and representing copolymer PVC-Polyacetylene. In samples with\nexcess of some \"threshold\" concentration of PCB with increasing temperature it\nwas found conductivity switching on 10 -11 orders of magnitude. Instability of\nstates with high conductivity in the temperature range which depends on the\nconcentration of PCB was detected. Qualitatively, the increase of concentration\nof PCB was monitored by fixing the fluorescent and absorption spectra.",
        "positive": "Crumpling a Thin Sheet: Crumpled sheets have a surprisingly large resistance to further compression.\nWe have studied the crumpling of thin sheets of Mylar under different loading\nconditions. When placed under a fixed compressive force, the size of a crumpled\nmaterial decreases logarithmically in time for periods up to three weeks. We\nalso find hysteretic behavior when measuring the compression as a function of\napplied force. By using a pre-treating protocol, we control this hysteresis and\nfind reproducible scaling behavior for the size of the crumpled material as a\nfunction of the applied force."
    },
    {
        "anchor": "Glassy dynamics of dense particle assemblies on a spherical substrate: We study by Molecular Dynamics simulation a dense one-component system of\nparticles confined on a spherical substrate. We more specifically investigate\nthe evolution of the structural and dynamical properties of the system when\nchanging the control parameters, the temperature and the curvature of the\nsubstrate. We find that the dynamics becomes glassy at low temperature, with a\nstrong slowdown of the relaxation and the emergence of dynamical heterogeneity.\nThe prevalent local $6$-fold order is frustrated by curvature and we analyze in\ndetail the role of the topological defects in the statics and the dynamics of\nthe particle assembly.",
        "positive": "Phase Transition in a Bond Fluctuating Lattice Polymer: This report deals with phase transition in Bond Fluctuation Model (BFM) of a\nlinear homo polymer on a two dimensional square lattice. Each monomer occupies\na unit cell of four lattice sites. The condition that a lattice site can at\nbest be a part of only one monomer ensures self avoidance and models excluded\nvolume effect. We have simulated polymers with number of monomers ranging from\n10 to 50 employing Boltzmann and non-Boltzmann Monte Carlo simulation\ntechniques. To detect and characterize phase transition we have investigated\nheat capacity through energy fluctuations, Landau free energy profiles and\nBinder's fourth cumulant. We have investigated (1) free standing polymer (2)\npolymer in the presence of of an attracting wall and (3) polymer confined\nbetween two attracting walls. In general we find there are two transitions as\nwe cool the system. The first occurs at relatively higher temperature. The\npolymer goes from an extended coil to a collapsed globule conformation. This we\ncall collapse transition. We find that this transition is first order. The\nsecond occurs at a lower temperature in which the polymer goes from a collapsed\nphase to a very compact crystalline phase. This transition is also\ndiscontinuous. We find that in the presence of wall(s) the collapse transition\noccurs at lower temperature compared to a free standing polymer."
    },
    {
        "anchor": "Stable and unstable capillary fingering in porous media with a gradient\n  in grains size: We present a theoretical and experimental investigation of slow drainage in\nporous media with a gradient in the grains size (and hence in the typical\npores' throats), in an external gravitational field. We mathematically show\nthat such structural gradient and external force have a similar effect on the\nobtained drainage patterns, when they stabilise the invasion front. With the\nhelp of a newly introduced experimental set-up, based on the 3D-print of\ntransparent porous matrices, we illustrate this equivalence, and extend it to\nthe case where the front is unstable. We also present some invasion-percolation\nsimulations of the same phenomena, which are inline with our theoretical and\nexperimental results. In particular, we show that the width of stable drainage\nfronts mainly scales with the spatial gradient of the average pore invasion\nthreshold and with the local distribution of this (disordered) threshold. The\nscaling exponent results from percolation theory and is -0.57 for 2D systems.\nOverall, we propose a unifying theory for the up-scaling of dual fluid flows in\nmost classical scenarii.",
        "positive": "G-quartet biomolecular nanowires: We present a first-principle investigation of quadruple helix nanowires,\nconsisting of stacked planar hydrogen-bonded guanine tetramers. Our results\nshow that long wires form and are stable in potassium-rich conditions. We\npresent their electronic bandstructure and discuss the interpretation in terms\nof effective wide-bandgap semiconductors. The microscopic structural and\nelectronic properties of the guanine quadruple helices make them suitable\ncandidates for molecular nanoelectronics."
    },
    {
        "anchor": "Liquid-liquid phase separation driven by charge heterogeneity: Globular proteins as well as recently synthesized colloids engineered with\ndifferently charged surface regions have in common a reduced bonding valence\nand a complex interaction pattern dominated by like-charge attraction and\nopposite-charge repulsion. While the impact of low functionality on the\ncondensation of the liquid phase has been extensively studied, the combined\neffect of limited bonding valence and particle charge heterogeneity on the\nliquid-liquid phase separation has not been investigated yet. We numerically\ntackle this challenge in a systematic fashion by taking advantage of an\nefficient coarse-grained model grounded into a robust mean-field description.\nWe consider a relatively simple surface pattern consisting of two charged polar\ncaps and an oppositely charged equatorial belt and investigate how the\ninterplay between geometry and electrostatics affect the critical point\nparameters. We find that electrostatics has a dramatic effect on the\ncondensation of the liquid phase -- especially in the regime of large polar\ncaps.",
        "positive": "A Continuum Theory of Dynamically Loaded Polymers: A thermo-mechanical continuum theory is proposed for dynamically loaded\nglassy polymers. The theory is based on an ansatz for the Helmholtz free energy\nwhere both the deviatoric and the volumetric contributions to the free energy\nare rate-dependent. The requirement that the free energy is fully rate\ndependent arises from the need to model the full range of conditions between\nthose found in quasi-static applications to those common in high-rate shock\nloading scenarios. Using a purely equilibrium equation of state is found to be\ninsufficient. The resulting model, called the Glassy Amorphous Polymer (GAP)\nmodel, suitably captures the thermo-mechanical behavior of both equilibrium\nproperties, but also high-rate phenomena like the shock Hugoniot.\nPolymethylmethacrylate (PMMA) is used as a representative polymer because it is\none of the few polymers where sufficient experiments have been done to\ndetermine many of the parameters required by the GAP model. An important part\nof the GAP model is the Hierarchical Flow Stress (HFS) model, which is shown to\naccurately represent the stress-strain behavior of PMMA over a broad range of\nstrain rates and temperatures. The HFS model replicates the details of stress\nplateau, softening, and hardening behavior observed in glassy amorphous\npolymers. The theory is not restricted to isothermal conditions. Analysis is\ndevoted to several issues associated with a non-equilibrium equation of state\n(EOS). Because data is insufficient for the full determination of the model's\nnon-equilibrium EOS, several plausible conditions called the quasi-equilibrium\nhypothesis are put forth to complete the model. Comparisons of experimental and\ntheoretical results over a wide-range of loading rates and conditions are\nreported."
    },
    {
        "anchor": "Coupling Turing stripes to active flows: We numerically solve the active nematohydrodynamic equations of motion,\ncoupled to a Turing reaction-diffusion model, to study the effect of active\nnematic flow on the stripe patterns resulting from a Turing instability. If the\nactivity is uniform across the system, the Turing patterns dissociate when the\nflux from active advection balances that from the reaction-diffusion process.\nIf the activity is coupled to the concentration of Turing morphogens, and\nneighbouring stripes have equal and opposite activity, the system self\norganises into a pattern of shearing flows, with stripes tending to fracture\nand slip sideways to join their neighbours. We discuss the role of active\ninstabilities in controlling the crossover between these limits, Our results\nare of relevance to mechanochemical coupling in biological systems.",
        "positive": "Rejuvenation and Memory Effects in a Structural Glass: We show numerically that a three-dimensional model for structural glass\ndisplays aging, rejuvenation and memory effects when submitted to a temperature\ncycle. These effects indicate that the free energy landscape of structural\nglasses may possess the complex hierarchical structure that characterize\nmaterials such as spin and polymer glasses. We use the theoretical concept of\nmarginal stability to interpret our results, and explain in which physical\nconditions a complex aging dynamics can emerge in dense supercooled liquids,\npaving the way for future experimental studies of complex aging dynamics in\ncolloidal and granular glasses."
    },
    {
        "anchor": "A Multi-scale Monte Carlo Method for Electrolytes: Artifacts arise in the simulations of electrolytes using periodic boundary\nconditions (PBC). We show the origin of these artifacts are the periodic image\ncharges and the constraint of charge neutrality inside the simulation box, both\nof which are unphysical from the view point of real systems. To cure these\nproblems, we introduce a multi-scale Monte Carlo method, where ions inside a\nspherical cavity are simulated explicitly, whilst ions outside are treated\nimplicitly using continuum theory. Using the method of Debye charging, we\nexplicitly derive the effective interactions between ions inside the cavity,\narising due to the fluctuations of ions outside. We find that these effective\ninteractions consist of two types: 1) a constant cavity potential due to the\nasymmetry of the electrolyte, and 2) a reaction potential that depends on the\npositions of all ions inside. Combining the Grand Canonical Monte Carlo (GCMC)\nwith a recently developed fast algorithm based of image charge method, we\nperform a multi-scale Monte Carlo simulation of symmetric electrolytes, and\ncompare it with other simulation methods, including PBC+GCMC method, as well as\nlarge scale Monte Carlo simulation. We demonstrate that our multi-scale MC\nmethod is capable of capturing the correct physics of a large system using a\nsmall scale simulation.",
        "positive": "Ionic conductivity of deep eutectic solvents: The role of orientational\n  dynamics and glassy freezing: We have performed a thorough examination of the reorientational relaxation\ndynamics and the ionic charge transport of three typical deep eutectic\nsolvents, ethaline, glyceline and reline by broadband dielectric spectroscopy.\nOur experiments cover a broad temperature range from the low-viscosity liquid\ndown to the deeply supercooled state, allowing to investigate the significant\ninfluence of glassy freezing on the ionic charge transport in these systems. In\naddition, we provide evidence for a close coupling of the ionic conductivity in\nthese materials to reorientational dipolar motions which should be considered\nwhen searching for deep eutectic solvents optimized for electrochemical\napplications."
    },
    {
        "anchor": "On the microscopic origin of Soret coefficient minima in liquid mixtures: Temperature gradients induce mass separation in mixtures in a process called\nthermodiffusion and quantified by the Soret coefficient. The existence of\nminima in the Soret coefficient of aqueous solutions was controversial until\nfairly recently, where a combination of experiments and simulations provided\nevidence for the existence of this physical phenomenon. However, the physical\norigin of the minima and more importantly its generality, e.g. in non-aqueous\nliquid mixtures, is still an outstanding question. We report the existence of a\nminimum in liquid mixtures of non-polar liquids modelled as Lennard-Jones\nmixtures, demonstrating the generality of this phenomenon. The Soret\ncoefficient minimum originates from a coincident minimum in the thermodynamic\nfactor, and hence denotes a maximimzation of non-ideality mixing conditions. We\nexplain the microscopic origin of this effect in terms of the atomic\ncoordination structure of the mixtures.",
        "positive": "Mixtures of foam and paste: suspensions of bubbles in yield stress\n  fluids: We study the rheological behavior of mixtures of foams and pastes, which can\nbe described as suspensions of bubbles in yield stress fluids. Model systems\nare designed by mixing monodisperse aqueous foams and concentrated emulsions.\nThe elastic modulus of the suspensions decreases with the bubble volume\nfraction. This decrease is all the sharper as the elastic capillary number\n(defined as the ratio of the paste elastic modulus to the bubble capillary\npressure) is high, which accounts for the softening of the bubbles as compared\nto the paste. By contrast, the yield stress of most studied materials is not\nmodified by the presence of bubbles. Their plastic behavior is governed by the\nplastic capillary number, defined as the ratio of the paste yield stress to the\nbubble capillary pressure. At low plastic capillary number values, bubbles\nbehave as nondeformable inclusions, and we predict that the suspension\ndimensionless yield stress should remain close to unity. At large plastic\ncapillary number values, we observe bubble breakup during mixing: bubbles are\ndeformed by shear. Finally, at the highest bubble volume fractions, the yield\nstress increases abruptly: this is interpreted as a 'foamy yield stress fluid'\nregime, which takes place when the paste mesoscopic constitutive elements are\nstrongly confined in the films between the bubbles."
    },
    {
        "anchor": "Effective Hamiltonian for fluid membranes in the presence of long-ranged\n  forces: If the constituent particles of fluid phases interact via long-ranged van der\nWaals forces, the effective Hamiltonian for \\emph{interfaces} between such\nfluid phases contains - in lateral Fourier space - non-analytic terms $ \\sim\nq^4 \\ln q$. Similar non-analytic terms characterize the effective Hamiltonian\nfor two interacting interfaces which can emerge between the three possible\ncoexisting fluid phases in binary liquid mixtures. This is in contrast with the\nstructure of the phenomenological Helfrich Hamiltonian for membranes which does\nnot contain such non-analytic terms. We show that under favorable conditions\nfor the bulk densities characterizing a binary liquid mixture and for the\nlong-ranged interparticle interactions the corresponding effective Hamiltonian\nfor a model fluid \\emph{membrane} does not exhibit such non-analytic\ncontributions. We discuss the properties of the resulting effective\nHamiltonian, with a particular emphasis on the influence of the long range of\nthe interactions on the coefficient of the bending rigidity.",
        "positive": "Soliton walls paired by polar surface interactions in a ferroelectric\n  nematic liquid crystal: Surface interactions are responsible for many properties of condensed matter,\nranging from crystal faceting to the kinetics of phase transitions. Usually,\nthese interactions are polar along the normal to the interface and apolar\nwithin the interface. Here, we demonstrate that polar in-plane surface\ninteractions of a ferroelectric nematic NF produce polar monodomains in\nmicron-thin planar cells and stripes of an alternating electric polarization,\nseparated by 180 degree domain walls, in thicker slabs. The surface polarity\nbinds together pairs of these walls, yielding a total polarization rotation by\n360 degrees. The polar contribution to the total surface anchoring strength is\non the order of 10%. The domain walls involve splay, bend, and twist of the\npolarization. The structure suggests that the splay elastic constant is larger\nthan the bend modulus. The 360 degree pairs resemble domain walls in cosmology\nmodels with biased vacuums and ferromagnets in an external magnetic field."
    },
    {
        "anchor": "Intramolecular phase separation of copolymer \"bottle brushes\": No sharp\n  phase transition but a tunable length scale: A lattice model for a symmetrical copolymer \"bottle brush\" molecule, where\ntwo types (A,B) of flexible side chains are grafted with one chain end to a\nrigid backbone, is studied by a variant of the pruned-enriched Rosenbluth\nmethod (PERM), allowing for simultaneous growth of all side chains in the Monte\nCarlo sampling. Choosing repulsive binary interactions between unlike monomers\nand varying the solvent quality, it is found that phase separation into an\n$A$-rich part of the cylindrical molecule and a $B$-rich part can occur only\nlocally. Long range order (in the direction of the backbone) does not occur,\nand hence the transition from the randomly mixed state of the bottle brush to\nthe phase separated structure is strongly rounded, in contrast to corresponding\nmean field predictions. This lack of a phase transition can be understood from\nan analogy with spin models in one space dimension. We predict that the range\nof microphase separation along the bottle brush backbone can be controlled on\nthe nanoscale by varying the solvent quality.",
        "positive": "Explaining Giant Apparent $\\mathrm{p}K_\\mathrm{A}$ Shifts in Weak\n  Polyelectrolyte Brushes: Recent experiments on weak polyelectrolyte brushes found marked shifts in the\neffective p$K_\\mathrm{A}$ that are linear in the logarithm of the salt\nconcentration. Comparing explicit-particle simulations with mean-field\ncalculations we show that for high grafting densities the salt concentration\neffect can be explained using the ideal Donnan theory, but for low grafting\ndensities the full shift is due to a combination of the Donnan effect and the\npolyelectrolyte effect. The latter originates from electrostatic correlations\nwhich are neglected in the Donnan picture and which are only approximately\nincluded in the mean-field theory. Moreover, we demonstrate that the magnitude\nof the polyelectrolyte effect is almost invariant with respect to salt\nconcentration but depends on the grafting density of the brush. This invariance\nis due to a complex cancellation of multiple effects. Based on our results, we\nshow how the experimentally determined p$K_\\mathrm{A}$ shifts may be used to\ninfer the grafting density of brushes, a parameter that is difficult to measure\ndirectly."
    },
    {
        "anchor": "Chemical Physics of Controlled Wettability and Super Surfaces: Wetting phenomena are widespread in both natural and technological contexts.\nDespite the well-established nature of this scientific field and our extensive\nknowledge of its underlying principles, wetting remains a dynamic and vibrant\narea of study. It continues to pose fundamental questions while offering\ninnovative avenues for controlling these phenomena to develop novel\napplications.\n  By tailoring the wetting properties of surfaces, researchers and engineers\ncan design materials with specific functionalities, such as self-cleaning\nsurfaces, anti-fog coatings, and enhanced slipperiness. Recent years have\nwitnessed significant advancements in wetting research, owing to the exquisite\ncontrol achieved in surface topography and chemistry and to the development of\nnovel experimental techniques. Additionally, simulations and theory have played\na crucial role in these advancements. They provid the fundamental knowledge and\nquantitative tools to control wettability and design surfaces with enhanced\nproperties.\n  Given these recent breakthroughs, this special collection Chemical Physics of\nControlled Wettability and Super Surfaces becomes particularly timely and\nsignificant. It serves as a platform to showcase some of the latest\ndevelopments in the field of wetting. It highlights the exciting progress and\npotential applications in controlling wetting properties that are enabled by\nthe synergy between theory, simulations, and experiments.",
        "positive": "Tilt Texture Domains on a Membrane and Chirality induced Budding: We study the equilibrium conformations of a lipid domain on a planar fluid\nmembrane where the domain is decorated by a vector field representing the tilt\nof the stiff fatty acid chains of the lipid molecules, while the surrounding\nmembrane is fluid and structureless. The inclusion of chirality in the bulk of\nthe domain induces a novel budding of the membrane, which preempts the budding\ninduced by a decrease in interfacial tension."
    },
    {
        "anchor": "Analysis of Cargo Loading Modes and Capacity of an Electrically-Powered\n  Active Carrier: The use of active colloids for cargo transport offers unique potential for\napplications ranging from targeted drug delivery to lab-on-a-chip systems.\nPreviously, Janus particles (JPs), acting as mobile microelectrodes have been\nshown to transport cargo which is trapped by a dielectrophoretic mechanism\n[Boymelgreen et al. (2018)]. Herein, we aim to characterize the cargo loading\nproperties of mobile Janus carriers, across a broad range of frequencies and\nvoltages. In expanding the frequency range of the carrier, we are able to\ncompare the influence of different modes of carrier transport on the loading\ncapacity as well as highlight the differences between cargo trapped by positive\nand negative dielectrophoresis. Specifically it is shown that cargo trapping\nresults in a reduction in carrier velocities with this effect more pronounced\nat low frequencies where cargo is trapped close to the substrate.\nInterestingly, we observe the existence of a maximum cargo loading capacity\nwhich decreases at large voltages suggesting a strong interplay between\ntrapping and hydrodynamic shear. Finally, we demonstrate that control of the\nfrequency can enable different assemblies of binary colloidal solutions on the\nJP. The resultant findings enable the optimization of electrokinetic cargo\ntransport and its selective application to a broad range of targets.",
        "positive": "Stability analysis of the D-dimensional nonlinear Schroedinger equation\n  with trap and two- and three-body interactions: Considering the static solutions of the D-dimensional nonlinear Schroedinger\nequation with trap and attractive two-body interactions, the existence of\nstable solutions is limited to a maximum critical number of particles, when D\nis greater or equal 2. In case D=2, we compare the variational approach with\nthe exact numerical calculations. We show that, the addition of a positive\nthree-body interaction allows stable solutions beyond the critical number. In\nthis case, we also introduce a dynamical analysis of the conditions for the\ncollapse."
    },
    {
        "anchor": "Orisometry formalism reveals duality and exotic nonuniform response in\n  origami sheets: Origami metamaterial design enables drastic qualitative changes in the\nresponse properties of a thin sheet via the addition of a repeating pattern of\nfolds based around a rigid folding motion. Known also as a mechanism, this\nfolding motion will have a very small energy cost when applied uniformly; and\nyet uniform activation of such remains highly difficult to observe, these\nsheets instead generically displaying nonuniform response patterns which are\nnot yet well understood. Here, we present a purely geometric continuum theory\nwhich captures the nonuniform, nonlinear response to generic loading as\ncomposed locally of the planar mechanism, as well as previously identified\n``twist'' and ``bend'' modes which enable the patterned sheet to curve out of\nthe plane across long distances. Our numerical analysis confirms that these\nthree modes govern the observed nonuniform response, varying smoothly across\nthe sheet according to three PDEs which guarantee compatibility. In analogy\nwith the recently solved case of planar mechanism metamaterials, these\n``Orisometries'' (origami + isometries, so named by us) are subextensive but\ninfinite in number, with each mode displaying, in the linear limit, ``sheared\nanalytic'' spatial patterns which are controlled by the Poisson's ratio of the\nuniform folding mechanism. Furthermore, the ``planar'' mechanism-based\ndeformation patterns superimpose with a mathematically dual space of\n``non-planar'' twist/bend deformations to span the available soft linear\nresponse. Together, our findings furnish the first quantification of the number\nof soft response modes available, as well as the first intuitive quantification\nof their spatial distribution.",
        "positive": "Preliminary experiments demonstrating a \"directed\" Maxwell's granular\n  demon: In this paper, we design a system of two symmetrical containers communicated\nby an aperture, in which a granular gas of glass spheres is created by shaking\nlaterally the whole system in a planetary mill. If the aperture consists in a\nsymmetrical hole, the two halves end up with the same number of grains after\nsome time when initially all particles are into in one of the containers.\nHowever, when a funnel-like aperture is used, a robust symmetry breaking is\ninduced: if all the grains are originally deposited in the container facing the\nwide side 95% of the grains pass to the opposite side in a relatively small\ntime."
    },
    {
        "anchor": "Medial packing, frustration and competing network phases in\n  strongly-segregated block copolymers: Self-consistent field theory (SCFT) has established that for cubic network\nphases in diblock copolymer melts, the double-gyroid (DG) is thermodynamically\nstable relative to the competitor double-diamond (DD) and double-primitive (DP)\nphases, and exhibits a window of stability intermediate to the classical\nlamellar and columnar phases. This competition is widely thought to be\ncontrolled by \"packing frustration\" -- the incompatibility of uniformly filling\nmelts with a locally preferred chain packing motif. Here, we reassess the\nthermodynamics of cubic network formation in strongly-segregated diblock melts,\nbased on a recently developed medial strong segregation theory (\"mSST\")\napproach that directly connects the shape and thermodynamics of chain packing\nenvironments to the medial geometry of tubular network surfaces. We first show\nthat medial packing significantly relaxes prior SST upper bounds on the free\nenergy of network phases, which we attribute to the spreading of terminal chain\nends within network nodal regions. Exploring geometric and thermodynamic\nmetrics of chain packing in network phases, we show that mSST reproduces\neffects dependent on the elastic asymmetry of the blocks that are consistent\nwith SCFT at large $\\chi N$. We then characterize geometric frustration in\nterms of the spatially-variant distributions of local entropic and enthalpic\ncosts throughout the morphologies, extracted from mSST predictions. We find\nthat the DG morphology, due to its unique medial geometry in the nodal regions,\nis stabilized by the incorporation of favorable, quasi-lamellar packing over\nmuch of its morphology, motifs which are inaccessible to DD and DP morphologies\ndue to \"interior corners\" in their medial geometries. Finally, we use our\nresults to analyze \"hot spots\" of chain stretching and discuss implications for\nnetwork susceptibility to the uptake of guest molecules.",
        "positive": "Dynamics and fragmentation of small inextensible fibers in turbulence: The fragmentation of small, brittle, flexible, inextensible fibers is\ninvestigated in a fully-developed, homogeneous, isotropic turbulent flow. Such\nsmall fibers spend most of their time fully stretched and their dynamics\nfollows that of stiff rods. They can then break through tensile failure, i.e.\nwhen the tension is higher than a given threshold. Fibers bend when\nexperiencing a strong compression. During these rare and intermittent buckling\nevents, they can break under flexural failure, i.e. when the curvature exceeds\na threshold. Fine-scale massive simulations of both the fluid flow and the\nfiber dynamics are performed to provide statistics on these two fragmentation\nprocesses. This gives ingredients for the development of accurate macroscopic\nmodels, namely the fragmentation rate and daughter-size distributions, which\ncan be used to predict the time evolution of the fiber size distribution.\nEvidence is provided for the generic nature of turbulent fragmentation and of\nthe resulting population dynamics. It is indeed shown that the statistics of\nbreakup is fully determined by the probability distribution of Lagrangian fluid\nvelocity gradients. This approach singles out that the only relevant\ndimensionless parameter is a local flexibility which balances flow stretching\nto the fiber elastic forces."
    },
    {
        "anchor": "Dewetting of thin polymer films near the glass transition: Dewetting of ultra-thin polymer films near the glass transition exhibits\nunexpected front morphologies [G. Reiter, Phys. Rev. Lett., 87, 186101 (2001)].\nWe present here the first theoretical attempt to understand these features,\nfocusing on the shear-thinning behaviour of these films. We analyse the profile\nof the dewetting film, and characterize the time evolution of the dry region\nradius, $R_{d}(t)$, and of the rim height, $h_{m}(t)$. After a transient time\ndepending on the initial thickness, $h_{m}(t)$ grows like $\\sqrt{t}$ while\n$R_{d}(t)$ increases like $\\exp{(\\sqrt{t})}$. Different regimes of growth are\nexpected, depending on the initial film thickness and experimental time range.",
        "positive": "Giant Activity-Induced Stress Plateau in Entangled Polymer Solutions: We study the viscoelastic properties of highly entangled, flexible,\nself-propelled polymers using Brownian dynamics simulations. Our results show\nthat the active motion of the polymer increases the height of the stress\nplateau by orders of magnitude due to the emergence of grip forces at\nentanglement points. Identifying the activity-induced energy of a single\npolymer and the ratio of polymer length to self-propulsion velocity as relevant\nenergy and time scales, we find the stress autocorrelation functions collapse\nacross P\\'eclet numbers. We predict that the long-time viscosity scales with\npolymer length squared $\\sim L^2$, in contrast to equilibrium counterparts\n$\\sim L^3$. These insights offer prospects for designing new materials with\nactivity-responsive mechanical properties."
    },
    {
        "anchor": "Pulling and Pushing a Cargo With a Catalytically Active Carrier: Catalytically active particles suspended in a liquid can move due to\nself-phoresis by generating solute gradients via chemical reactions of the\nsolvent occurring at parts of their surface. Such particles can be used as\ncarriers at the micro-scale. As a simple model for a carrier-cargo system we\nconsider a catalytically active particle connected by a thin rigid rod to a\ncatalytically inert cargo particle. We show that the velocity of the composite\nstrongly depends on the relative orientation of the carrier-cargo link.\nAccordingly, there is an optimal configuration for the linkage. The subtlety of\nsuch carriers is underscored by the observation that a spherical particle\ncompletely covered by catalyst, which is motionless when isolated, acts as a\ncarrier once attached to a cargo.",
        "positive": "Spontaneous surface reserve formation in wicked membranes bestow extreme\n  stretchability: Soft stretchable materials are key for arising technologies such as\nstretchable electronics or batteries, smart textiles, biomedical devices,\ntissue engineering and soft robotics. Recent attempts to design such materials,\nvia e.g. micro-patterning of wavy fibres on soft substrates, polymer\nengineering at the molecular level or even kirigami techniques, provide\nappealing prospects but suffer drawbacks impacting the material viability:\ncomplexity of manufacturing, fatigue or failure upon cycling, restricted range\nof materials or biological incompatibility. Here, we report a universal\nstrategy to design highly stretchable, self-assembling and fatigue-resistant\nsynthetic fabrics. Our approach finds its inspiration in the mechanics of\nliving animal cells that routinely encounter and cope with extreme\ndeformations, e.g. with the engulfment of large intruders by macrophages,\nsqueezing and stretching of immune cells in tiny capillaries or\nshrinking/swelling of neurons upon osmotic stimuli. All these large instant\ndeformations are actually mediated and buffered by membrane reserves available\nin the form of microvilli, membrane folds or endomembrane that can be recruited\non demand. We synthetically mimicked this behavior by creating nanofibrous\nliquid-infused tissues spontaneously forming surface reserves whose unfolding\nfuels any imposed shape change. Our process, relying only on geometry,\nelasticity and capillarity, allows to endow virtually any material with high\nstretchability and reversibility, making it straightforward to implement\nadditional mechanical, electrical or chemical functions. We illustrate this\nwith proof-of-concept activable capillary muscles, adaptable slippery liquid\ninfused porous surfaces and stretchable basic printed electronic circuits."
    },
    {
        "anchor": "Collective diffusion coefficient of proteins with hydrodynamic,\n  electrostatic and adhesive interactions: A theory is presented for lambda_C, the coefficient of the first-order\ncorrection in the density of the collective diffusion coefficient, for protein\nspheres interacting by electrostatic and adhesive forces. An extensive\nnumerical analysis of the Stokesian hydrodynamics of two moving spheres is\ngiven so as to gauge the precise impact of lubrication forces. An effective\nstickiness is introduced and a simple formula for lambda_C in terms of this\nvariable is put forward. A precise though more elaborate approximation for\nlambda_C is also developed. These and numerically exact expressions for\nlambda_C are compared with experimental data on lysozyme at pH 4.5 and a range\nof ionic strengths between 0.05 M and 2 M.",
        "positive": "Direct Numerical Simulations of Electrophoresis of Charged Colloids: We propose a numerical method to simulate electrohydrodynamic phenomena in\ncharged colloidal dispersions. This method enables us to compute the time\nevolutions of colloidal particles, ions, and host fluids simultaneously by\nsolving Newton, advection-diffusion, and Navier--Stokes equations so that the\nelectrohydrodynamic couplings can be fully taken into account. The\nelectrophoretic mobilities of charged spherical particles are calculated in\nseveral situations. The comparisons with approximation theories show\nquantitative agreements for dilute dispersions without any empirical\nparameters, however, our simulation predicts notable deviations in the case of\ndense dispersions."
    },
    {
        "anchor": "Shape Bistability in Squeezed Chromonic Droplets: We study droplets of chromonic liquid crystals squeezed between parallel\nplates inducing degenerate tangential anchoring on the nematic director. In the\ncoexistence regime, where droplets in the nematic phase are at equilibrium with\nthe surrounding melt, our two-dimensional theoretical model predicts a regime\nof shape bistability for sufficiently large bipolar droplets, where tactoids\n(pointed shapes) and discoids (smooth shapes) coexist in equilibrium. This\nphenomenon has not yet been observed. Two-dimensional droplets of disodium\ncromoglycate (DSCG) have been the object of a thorough experimental study\n[Y.-K. Kim et al., J. Phys.: Condens. Matter 25, 404202 (2013)]. We show that\nour theory is in good quantitative agreement with these data and extract from\nthem what promises to be a more accurate estimate for the isotropic surface\ntension at the nematic/melt interface of DSCG.",
        "positive": "Elliptic Phases: A Study of the Nonlinear Elasticity of Twist-Grain\n  Boundaries: We develop an explicit and tractable representation of a twist-grain-boundary\nphase of a smectic A liquid crystal. This allows us to calculate the\ninteraction energy between grain boundaries and the relative contributions from\nthe bending and compression deformations. We discuss the special stability of\nthe 90 degree grain boundaries and discuss the relation of this structure to\nthe Schwarz D surface."
    },
    {
        "anchor": "Two-scale scenario of rigidity percolation of sticky particles: In the presence of attraction, the jamming transition of packings of\nfrictionless particles corresponds to the rigidity percolation. When the range\nof attraction is long, the distribution of the size of rigid clusters, $P(s)$,\nis continuous and shows a power-law decay. For systems with short-range\nattractions, however, $P(s)$ appears discontinuous. There is a power-law decay\nfor small cluster sizes, followed by a low probability gap and a peak near the\nsystem size. We find that this appearing ``discontinuity'' does not mean that\nthe transition is discontinuous. In fact, it signifies the coexistence of two\ndistinct length scales, associated with the largest cluster and smaller ones,\nrespectively. The comparison between the largest and second largest clusters\nindicates that their growth rates with system size are rather different.\nHowever, both cluster sizes tend to diverge in the large system size limit,\nsuggesting that the jamming transition of systems with short-range attractions\nis still continuous. In the framework of the two-scale scenario, we also derive\na generalized hyperscaling relation. With robust evidence, our work challenges\nthe former single-scale view of the rigidity percolation.",
        "positive": "Orientational arrest in dense suspensions of elliptical particles under\n  oscillatory shear flows: We study the rheological response of dense suspensions of elliptical\nparticles, with an aspect ratio equal to 3, under oscillatory shear flows and\nimposed pressure by numerical simulations. Like for the isotropic particles, we\nfind that the oscillatory shear flows respect the Cox-Merz rule at large\noscillatory strains but differ at low strains, with a lower viscosity than the\nsteady shear and higher shear jamming packing fractions. However, unlike the\nisotropic cases (i.e., discs and spheres), frictionless ellipses get\ndynamically arrested in their initial orientational configuration at small\noscillatory strains. We illustrate this by starting at two different\nconfigurations with different nematic order parameters and the average\norientation of the particles. Surprisingly, the overall orientation in the\nfrictionless case is uncoupled to the rheological response close to jamming,\nand the rheology is only controlled by the average number of contacts and the\noscillatory strain. Having larger oscillatory strains or adding friction does,\nhowever, help the system escape these orientational arrested states, which are\nevolving to a disordered state independent of the initial configuration at low\nstrains and ordered ones at large strains."
    },
    {
        "anchor": "Scattering from Solutions of Star Polymers: We calculate the scattering intensity of dilute and semi-dilute solutions of\nstar polymers. The star conformation is described by a model introduced by\nDaoud and Cotton. In this model, a single star is regarded as a spherical\nregion of a semi-dilute polymer solution with a local, position dependent\nscreening length. For high enough concentrations, the outer sections of the\narms overlap and build a semi-dilute solution (a sea of blobs) where the inner\nparts of the actual stars are embedded. The scattering function is evaluated\nfollowing a method introduced by Auvray and de Gennes. In the dilute regime\nthere are three regions in the scattering function: the Guinier region (low\nwave vectors, q R << 1) from where the radius of the star can be extracted; the\nintermediate region (1 << q R << f^(2/5)) that carries the signature of the\nform factor of a star with f arms: I(q) ~ q^(-10/3); and a high wavevector zone\n(q R >> f^(2/5)) where the local swollen structure of the polymers gives rise\nto the usual q^(-5/3) decay. In the semi-dilute regime the different stars\ninteract strongly, and the scattered intensity acquires two new features: a\nliquid peak that develops at a reciprocal position corresponding to the\nstar-star distances; and a new large wavevector contribution of the form\nq^(-5/3) originating from the sea of blobs.",
        "positive": "BCS superfluidity in ultracold gases with unequal atomic populations: We consider the existence of a BCS superfluid phase in $^{6}$Li due to the\npairing of two hyperfine states with unequal number of atoms. We show that the\ndomain of existence for this phase will be increased to a very large extent in\nthe vicinity of the threshold for collapse. This is due to the presence of a\nnew phase with anisotropic order parameter. This phase is induced by the\nanisotropic part of the scattering, linked to the indirect interaction between\natoms through density fluctuation exchange."
    },
    {
        "anchor": "Pair Dispersion in Dilute Suspension of Active Swimmers: Ensembles of biological and artificial microswimmers produce long-range\nvelocity fields with strong nonequilibrium fluctuations, which result in\ndramatic increase diffusivity of embedded particles (tracers). While such\nenhanced diffusivity may point to enhanced mixing of the fluid, a rigorous\nquantification of the mixing efficiency requires analysis of pair dispersion of\ntracers, rather than simple one-particle diffusivity. Here, we calculate\nanalytically the scale-dependent coefficient of relative diffusivity of passive\ntracers embedded in a dilute suspension of run-and-tumble microswimmers.\nAlthough each tracer is subject to strong fluctuations resulting in large\nabsolute diffusivity, the small-scale relative dispersion is suppressed due to\nthe correlations in fluid velocity which are relevant when the inter-tracers\nseparation is below the persistence length of the swimmers motion. Our results\nsuggest that the reorientation of swimming direction plays an important role in\nbiological mixing and should be accounted in design of potential active matter\ndevices capable of effective fluid mixing at microscale.",
        "positive": "Exact calculations of the paranematic interaction energy for colloidal\n  dispersions in the isotropic phase of a nematogenic material: In a recent paper [Phys. Rev. E 61, 2831 (2000)], Borstnik, Stark and Zumer\nhave studied the stability of a colloidal dispersion of micron-sized spherical\nparticles in the isotropic phase of a nematogenic material. Close to the\nnematic transition, the attraction due to a surface-induced paranematic order\ncan yield flocculation. Their calculation of the nematic-mediated interaction\nwas based on an ansatz for the order-parameter profile. We compare it with an\nexact numerical calculation, showing that their results are qualitatively\ncorrect. Besides, we point out that in the considered regime, the exact\ninteraction is extremely well approximated by a simple analytical formula which\nis asymptotically exact."
    },
    {
        "anchor": "Collective effects in cellular structure formation mediated by compliant\n  environments: a Monte Carlo study: Compliant environments can mediate interactions between mechanically active\ncells like fibroblasts. Starting with a phenomenological model for the\nbehaviour of single cells, we use extensive Monte Carlo simulations to predict\nnon-trivial structure formation for cell communities on soft elastic substrates\nas a function of elastic moduli, cell density, noise and cell position\ngeometry. In general, we find a disordered structure as well as ordered\nstring-like and ring-like structures. The transition between ordered and\ndisordered structures is controlled both by cell density and noise level, while\nthe transition between string- and ring-like ordered structures is controlled\nby the Poisson ratio. Similar effects are observed in three dimensions. Our\nresults suggest that in regard to elastic effects, healthy connective tissue\nusually is in a macroscopically disordered state, but can be switched to a\nmacroscopically ordered state by appropriate parameter variations, in a way\nthat is reminiscent of wound contraction or diseased states like contracture.",
        "positive": "Monte Carlo Procedure for Protein Design: A new method for sequence optimization in protein models is presented. The\napproach, which has inherited its basic philosophy from recent work by Deutsch\nand Kurosky [Phys. Rev. Lett. 76, 323 (1996)] by maximizing conditional\nprobabilities rather than minimizing energy functions, is based upon a novel\nand very efficient multisequence Monte Carlo scheme. By construction, the\nmethod ensures that the designed sequences represent good folders\nthermodynamically. A bootstrap procedure for the sequence space search is\ndevised making very large chains feasible. The algorithm is successfully\nexplored on the two-dimensional HP model with chain lengths N=16, 18 and 32."
    },
    {
        "anchor": "Discrete-element simulation of particle breakage inside ball mills: A 2D\n  model: In this paper, the grinding of powder inside a ball mill is studied using the\nBonded Cell Method (BCM) implemented in the framework of Contact Dynamics. In\nBCM the parent particles are divided into cells that are glued to one another\nuntil, under the action of external loading, both a cohesion threshold and a\ncertain distance threshold are reached. Numerical simulations of a rotating\nhollow cylinder filled with a mixture of heavy balls and powder crushable\nparticles were carried out. Systems with balls of different sizes and/or\nnumbers are compared in terms of the evolution of the powder particle size and\nspecific surface. We find that, in general, the milling process is increasingly\nfaster as the ball size increases. But energy dissipation due to increased\ncollisions between balls slows down the grinding process and makes it\nenergetically less efficient. On the other hand, when the total volume of balls\nis kept constant, the ball size is not relevant for the evolution of particle\nbreakage except in the limit cases of very small and very large ball sizes.",
        "positive": "Wetting transitions of polymer solutions: Effects of chain length and\n  chain stiffness: Wetting and drying phenomena are studied for flexible and semiflexible\npolymer solutions via coarse-grained molecular dynamics simulations and density\nfunctional theory calculations. The study is based on the use of Young's\nequation for the contact angle, determining all relevant surface tensions from\nthe anisotropy of the pressure tensor. The solvent quality (or effective\ntemperature, equivalently) is varied systematically, while all other\ninteractions remain unaltered. For flexible polymers, the wetting transition\ntemperature $T_{\\rm w}$ increases monotonically with chain length $N$, while\nthe contact angle at temperatures far below $T_{\\rm w}$ is independent of $N$.\nFor semiflexible polymer solutions, $T_{\\rm w}$ varies non-monotonically with\nthe persistence length: Initially, $T_{\\rm w}$ increases with increasing chain\nstiffness and reaches a maximum, but then a sudden drop of $T_{\\rm w}$ is\nobserved, which is associated with the isotropic-nematic transition of the\nsystem."
    },
    {
        "anchor": "Monte Carlo simulation of the electrical properties of electrolytes\n  adsorbed in charged slit-systems: We study the adsorption of primitive model electrolytes into a layered slit\nsystem using grand canonical Monte Carlo simulations. The slit system contains\na series of charged membranes. The ions are forbidden from the membranes, while\nthey are allowed to be adsorbed into the slits between the membranes. We focus\non the electrical properties of the slit system. We show concentration, charge,\nelectric field, and electrical potential profiles. We show that the potential\ndifference between the slit system and the bulk phase is mainly due to the\ndouble layers formed at the boundaries of the slit system, but polarization of\nexternal slits also contributes to the potential drop. We demonstrate that the\nelectrical work necessary to bring an ion into the slit system can be studied\nonly if we simulate the slit together with the bulk phases in one single\nsimulation cell.",
        "positive": "Cross-linker unbinding and self-similarity in bundled cytoskeletal\n  networks: The macromechanical properties of purely bundled in vitro actin networks are\nnot only determined by the micromechanical properties of individual bundles but\nalso by molecular unbinding events of the actin binding protein (ABP) fascin.\nUnder high mechanical load the network elasticity depends on the forced\nunbinding of individual ABPs in a rate dependent manner. Cross-linker unbinding\nin combination with the structural self-similarity of the network enables the\nintroduction of a concentration/time superposition principle - broadening the\nmechanically accessible frequency range over 8 orders of magnitude."
    },
    {
        "anchor": "Microphase separation in polyelectrolytic diblock copolymer melt : weak\n  segregation limit: We present a generalized theory of microphase separation for charged-neutral\ndiblock copolymer melt. Stability limit of the disordered phase for salt-free\nmelt has been calculated using Random Phase Approximation (RPA) and\nself-consistent field theory (SCFT). Explicit analytical free energy\nexpressions for different classical ordered microstructures (lamellar, cylinder\nand sphere) are presented. We demonstrate that chemical mismatch required for\nthe onset of microphase separation ($\\chi^{\\star} N$) in charged-neutral\ndiblock melt is higher and the period of ordered microstructures is lower than\nthose for the corresponding neutral-neutral diblock system. Theoretical\npredictions on the period of ordered structures in terms of Coulomb\nelectrostatic interaction strength, chain length, block length, and the\nchemical mismatch between blocks are presented. SCFT has been used to go beyond\nthe stability limit, where electrostatic potential and charge distribution are\ncalculated self-consistently. Stability limits calculated using RPA are in\nperfect agreement with the corresponding SCFT calculations. Limiting laws for\nstability limit and the period of ordered structures are presented and\ncomparisons are made with an earlier theory. Also, transition boundaries\nbetween different morphologies have been investigated.",
        "positive": "Scaling exponents and probability distributions of DNA end-to-end\n  distance: Correlation length exponent $\\nu$ for long linear DNA molecules was\ndetermined by direct measurement of the average end-to-end distance as a\nfunction of the contour length $s$ by means of atomic force microscopy (AFM).\nLinear DNA, up to 48'502 base pairs (bp), was irreversibly deposited from a\nsolution onto silanized mica and imaged in air. Under the adsorption conditions\nused, the DNA is trapped onto the surface without any two-dimensional\nequilibration. The measured exponent is $\\nu = 0.589 \\pm 0.006$, in agreement\nwith the theoretical 3D value of $\\nu = 0.5880 \\pm 0.0010$. The persistence\nlength $\\ell_p$ of DNA was estimated to be 44$\\pm$3 nm, in agreement with the\nliterature values. The distribution of the end-to-end distances for a given\ncontour length $s$ and the exponents characterizing the distribution were\ndetermined for different $s$. For $s$ smaller or comparable to $\\ell_p$, a\ndelta function like distribution was observed, while for larger $s$, a\nprobability distribution of the type $x^{d-1}x^g e^{-bx^\\delta}$ was observed\nwith $g=0.33\\pm0.22$ and $\\delta=2.58\\pm0.76$. These values are compared to the\ntheoretical exponents for Self-Avoiding Walk (SAW): namely\n$g=\\frac{\\gamma-1}{\\nu}$ and $\\delta=(1-\\nu)^{-1}$. So for $d=2$,\n$g\\approx0.44$ and $\\delta=4$, while for $d=3$, $g\\approx0.33$ and\n$\\delta\\approx2.5$. The derived entropic exponent $\\gamma$ is\n$\\gamma=1.194\\pm0.129$. The present data indicate that the DNA behaves on large\nlength scales like a 3 dimensional SAW."
    },
    {
        "anchor": "Does confining the hard-sphere fluid between hard walls change its\n  average properties?: We use grand canonical transition-matrix Monte Carlo and discontinuous\nmolecular dynamics simulations to generate precise thermodynamic and kinetic\ndata for the equilibrium hard-sphere fluid confined between smooth hard walls.\nThese simulations show that the pronounced inhomogeneous structuring of the\nfluid normal to the confining walls, often the primary focus of density\nfunctional theory studies, has a negligible effect on many of its average\nproperties over a surprisingly broad range of conditions. We present one\nconsequence of this insensitivity to confinement: a simple analytical equation\nrelating the average density of the confined fluid to that of the bulk fluid\nwith equal activity. Nontrivial implications of confinement for average fluid\nproperties do emerge in this system, but only when the fluid is both (i) dense\nand (ii) confined to a gap smaller than approximately three particle diameters.\nFor this limited set of conditions, we find that \"in-phase\" oscillatory\ndeviations in excess entropy and self-diffusivity (relative to the behavior of\nthe bulk fluid at the same average density) occur as a function of gap size.\nThese paired thermodynamic/kinetic deviations from bulk behavior appear to\nreflect the geometric packing frustration that arises when the confined space\ncannot naturally accommodate an integer number of particle layers.",
        "positive": "Numerical solutions of thin film equations for polymer flows: We report on the numerical implementation of thin film equations that\ndescribe the capillary-driven evolution of viscous films, in two-dimensional\nconfigurations. After recalling the general forms and features of these\nequations, we focus on two particular cases inspired by experiments: the\nleveling of a step at the free surface of a polymer film, and the leveling of a\npolymer droplet over an identical film. In each case, we first discuss the\nlong-term self-similar regime reached by the numerical solution before\ncomparing it to the experimental profile. The agreement between theory and\nexperiment is excellent, thus providing a versatile probe for nanorheology of\nviscous liquids in thin film geometries."
    },
    {
        "anchor": "Trapping reactions with subdiffusive traps and particles: Reaction dynamics involving subdiffusive species is an interesting topic with\nonly few known results, especially when the motion of different species is\ncharacterized by different anomalous diffusion exponents. Here we study the\nreaction dynamics of a (sub)diffusive particle surrounded by a sea of\n(sub)diffusive traps in one dimension. Under some reasonable assumptions we\nfind rigorous results for the asymptotic survival probability of the particle\nin most cases, but have not succeeded in doing so for a particle that diffuses\nnormally while the anomalous diffusion exponent of the traps is smaller than\n2/3.",
        "positive": "Derivation and analysis of a phase field crystal model for a mixture of\n  active and passive particles: We discuss an active phase field crystal (PFC) model that describes a mixture\nof active and passive particles. First, a microscopic derivation from dynamical\ndensity functional theory (DDFT) is presented that includes a systematic\ntreatment of the relevant orientational degrees of freedom. Of particular\ninterest is the construction of the nonlinear and coupling terms. This allows\nfor interesting insights into the microscopic justification of phenomenological\nconstructions used in PFC models for active particles and mixtures, the\napproximations required for obtaining them, and possible generalizations.\nSecond, the derived model is investigated using linear stability analysis and\nnonlinear methods. It is found that the model allows for a rich nonlinear\nbehavior with states ranging from steady periodic and localized states to\nvarious time-periodic states. The latter include standing, traveling, and\nmodulated waves corresponding to spatially periodic and localized traveling,\nwiggling, and alternating peak patterns and their combinations."
    },
    {
        "anchor": "The fluid dynamics of collective vortex structures of plant-animal worms: Circular milling, a stunning manifestation of collective motion, is found\nacross the natural world, from fish shoals to army ants. It has been observed\nrecently that the plant-animal worm $Symsagittifera~roscoffensis$ exhibits\ncircular milling behaviour, both in shallow pools at the beach and in Petri\ndishes in the laboratory. Here we investigate this phenomenon, through\nexperiment and theory, from a fluid dynamical viewpoint, focusing on the effect\nthat an established circular mill has on the surrounding fluid. Unlike systems\nsuch as confined bacterial suspensions and collections of molecular motors and\nfilaments that exhibit spontaneous circulatory behaviour, and which are\nmodelled as force dipoles, the front-back symmetry of individual worms\nprecludes a stresslet contribution. Instead, singularities such as source\ndipoles and Stokes quadrupoles are expected to dominate. A series of models is\nanalyzed to understand the contributions of these singularities to the\nazimuthal flow fields generated by a mill, in light of the particular boundary\nconditions that hold for flow in a Petri dish. A model that treats a circular\nmill as a rigid rotating disc that generates a Stokes flow is shown to capture\nbasic experimental results well, and gives insights into the emergence and\nstability of multiple mill systems.",
        "positive": "Play. Pause. Rewind. Measuring local entropy production and extractable\n  work in active matter: Time-reversal symmetry breaking and entropy production are universal features\nof nonequilibrium phenomena. Despite its importance in the physics of active\nand living systems, the entropy production of systems with many degrees of\nfreedom has remained of little practical significance because the\nhigh-dimensionality of their state space makes it difficult to measure. Here we\nintroduce a local measure of entropy production and a numerical protocol to\nestimate it. We establish a connection between the entropy production and\nextractability of work in a given region of the system and show how this\nquantity depends crucially on the degrees of freedom being tracked. We validate\nour approach in theory, simulation, and experiments by considering systems of\nactive Brownian particles undergoing motility induced phase separation, as well\nas active Brownian particles and E. Coli in a rectifying device in which the\ntime-reversal asymmetry of the particle dynamics couples to spatial asymmetry\nto reveal its effects on a macroscopic scale."
    },
    {
        "anchor": "Molecular Dynamics Simulation of Water between Metal Walls under\n  Electric Field: Dielectric Response and Dynamics after Field Reversal: We study water between parallel metal walls under applied electric field\naccounting for the image effect at $T=298$ K. The electric field due to the\nsurface charges serves to attract and orient nearby water molecules, while it\ntends to a constant determined by the mean surface charge density away from the\nwalls. We find Stern boundary layers with thickness about $5$ $\\rm \\AA$ and a\nhomogeneously polarized bulk region. The molecules in the layers more\nsensitively respond to the applied field than in the bulk. As a result, the\npotential drop in the layers is larger than that in the bulk unless the cell\nlength exceeds 10 nm. We also examine the hydrogen bonds, which tend to make\nsmall angles with respect to the walls in the layers even without applied\nfield. The average local field considerably deviates from the classical Lorentz\nfield and the local field fluctuations are very large in the bulk. If we\nsuppose a nanometer-size sphere around each molecule, the local field\ncontribution from its exterior is nearly equal to that from the continuum\nelectrostatics and that from its interior yields the deviation from the\nclassical Lorentz field. As a nonequilibrium problem, we investigate the\ndynamics after a reversal of applied field, where the relaxation is mostly\ncaused by large-angle rotational jumps after 1 ps due to the presence of the\nhydrogen bond network. The molecules undergoing these jumps themselves form\nhydrogen-bonded clusters heterogeneously distributed in space.",
        "positive": "Tuning for fluidity using fluctuations in biological tissue models: How do biological systems tune emergent properties at the scale of tissues?\nOne class of such emergent behaviors, important to biological functions such as\nbody-axis elongation, involves rigidity transitions, in which a tissue changes\nfrom a fluid-like state to a solid-like state or vice versa. Here, we explore\nthe idea that tissues might tune ``learning degrees of freedom\" to affect this\nemergent behavior. We study tissue fluidity in the 2D vertex model, using the\nvertex model energy as a learning cost function and the cell stiffnesses,\ntarget shapes, and target areas as sets of learning degrees of freedom that can\nbe varied to minimize the energy. We show that the rigidity transition is\nunaffected when cell stiffnesses are treated as learning degrees of freedom.\nWhen preferred perimeters or areas are treated as learning degrees of freedom,\nhowever, energy minimization introduces spatial correlations in target cell\nshapes or areas that shift the rigidity transition. There is an optimal\nheterogeneity of target cell shapes or areas to enable learning. These\nobservations suggest that biological tissues can learn tissue-scale behaviors\nby tuning their individual cell properties."
    },
    {
        "anchor": "Correlations in suspensions confined between viscoelastic surfaces:\n  Noncontact microrheology: We study theoretically the velocity cross-correlations of a viscous fluid\nconfined in a slit between two viscoelastic media. We analyze the effect of\nthese correlations on the motions of particles suspended in the fluid. The\ncompliance of the confining boundaries gives rise to a long-ranged pair\ncorrelation, decaying only as $1/r$ with the interparticle distance $r$. We\nshow how this long-ranged effect may be used to extract the viscoelastic\nproperties of the confining media without embedding tracer particles in them.\nWe discuss the remarkable robustness of such a potential technique with respect\nto details of the confinement, and its expected statistical advantages over\nstandard two-point microrheology.",
        "positive": "Wertheim's thermodynamic perturbation theory with double-bond\n  association and its application to colloid-linker mixtures: We extend Wertheim's thermodynamic perturbation theory to derive the\nassociation free energy of a multicomponent mixture for which double bonds can\nform between any two pairs of the molecules' arbitrary number of bonding sites.\nThis generalization reduces in limiting cases to prior theories that restrict\ndouble bonding to at most one pair of sites per molecule. We apply the new\ntheory to an associating mixture of colloidal particles (\"colloids\") and\nflexible chain molecules (\"linkers\"). The linkers have two functional end\ngroups, each of which may bond to one of several sites on the colloids. Due to\ntheir flexibility, a significant fraction of linkers can \"loop\" with both ends\nbonding to sites on the same colloid instead of bridging sites on different\ncolloids. We use the theory to show that the fraction of linkers in loops\ndepends sensitively on the linker end-to-end distance relative to the colloid\nbonding-site distance, which suggests strategies for mitigating the loop\nformation that may otherwise hinder linker-mediated colloidal assembly."
    },
    {
        "anchor": "Threading Dynamics of Ring Polymers in a Gel: We perform large scale three-dimensional molecular dynamics simulations of\nunlinked and unknotted ring polymers diffusing through a background gel, here a\nthree-dimensional cubic lattice. Taking advantage of this architecture, we\npropose a new method to unambiguously identify and quantify inter-ring\nthreadings (penetrations) and to relate these to the dynamics of the ring\npolymers. We find that both the number and the persistence time of the\nthreadings increase with the length of the chains, ultimately leading to a\npercolating network of inter-ring penetrations. We discuss the implications of\nthese findings for the possible emergence of a topological jammed state of very\nlong rings.",
        "positive": "Second variation of the Helfrich-Canham Hamiltonian and\n  reparametrization invariance: A covariant approach towards a theory of deformations is developed to examine\nboth the first and second variation of the Helfrich-Canham Hamiltonian --\nquadratic in the extrinsic curvature -- which describes fluid vesicles at\nmesoscopic scales. Deformations are decomposed into tangential and normal\ncomponents; At first order, tangential deformations may always be identified\nwith a reparametrization; at second order, they differ. The relationship\nbetween tangential deformations and reparametrizations, as well as the coupling\nbetween tangential and normal deformations, is examined at this order for both\nthe metric and the extrinsic curvature tensors. Expressions for the expansion\nto second order in deformations of geometrical invariants constructed with\nthese tensors are obtained; in particular, the expansion of the Hamiltonian to\nthis order about an equilibrium is considered. Our approach applies as well to\nany geometrical model for membranes."
    },
    {
        "anchor": "Asymmetric Assembly of Lennard-Jones Janus Dimers: Self-assembly of Janus (or `patchy') particles is dependent on the precise\ninteraction between neighbouring particles. Here, the orientations of two\namphiphilic Janus spheres within a dimer in an explicit fluid are studied with\nhigh geometric resolution. Molecular dynamics simulations and first-principles\nenergy calculations are used with hard- and soft-sphere Lennard-Jones\npotentials, and temperature and hydrophobicity are varied. The most probable\ncentre-centre-pole angles are in the range 40{\\deg} to 55{\\deg}, with\npole-to-pole alignment not observed due to orientational entropy. Angles near\n90{\\deg} are energetically unfavoured due to solvent exclusion, and we\nunexpectedly found that the relative azimuthal angle between the spheres is\naffected by solvent ordering.",
        "positive": "Densitaxis: Active particle motion in density gradients: Organisms often swim through density stratified fluids. In this Letter, we\ninvestigate the dynamics of small active particles swimming in density\ngradients and report theoretical evidence of taxis as a result of density\nstratification ($\\textit{densitaxis}$). Specifically, we calculate the effect\nof density stratification on the dynamics of a force-free spherical squirmer\nand show that density stratification induces reorientation that tends to align\nswimming either parallel or normal to the gradient depending on the swimming\ngait. In particular, particles that propel by generating thrust in the front\n(pullers) rotate to swim parallel to gradients and hence display (positive or\nnegative) densitaxis, while particles that propel by generating thrust in the\nback (pushers) rotate to swim normal to the gradients. This work could be\nuseful to understand the motion of marine organisms in ocean, or be leveraged\nto sort or organize a suspension of active particles by modulating density\ngradients."
    },
    {
        "anchor": "Lipid Segregation on Cylindrically and Spherically Curved Membranes: We investigate how an externally imposed curvature influences lipid\nsegregation on two-phase-coexistent membranes. We show that the bending-modulus\ncontrast of the two phases and the curvature act together to yield a reduced\neffective line tension. On largely curved membranes, a state of multiple\ndomains (or rafts) forms due to a mechanism analogous to that causing\nmagnetic-vortex formation in type-II superconductors. We determine the\ncriterion for such multi-domain state to occur; we then calculate respectively\nthe size of the domains formed on cylindrically and spherically curved\nmembranes.",
        "positive": "Towards Relating Fragile-To-Strong Transition to Fragile Glass: Glass formers are in general classified as strong or fragile depending on\nwhether their relaxation rates follow Arrhenius or super-Arrhenius temperature\ndependence. There are however notable exceptions such as water, which exhibit a\nfragile-to-strong (FTS) transition and behave as fragile and strong\nrespectively at high and low temperatures. In this work, the FTS transition is\nstudied using a distinguishable-particle lattice model previously demonstrated\nto be capable of simulating both strong and fragile glasses [Phys. Rev. Lett.\n125, 265703 (2020)]. Starting with a bimodal pair-interaction distribution\nappropriate for fragile glasses, we show that by narrowing down the energy\ndispersion in the low-energy component of the distribution, a FTS transition is\nobserved. The transition occurs at a temperature at which the stretching\nexponent of the relaxation is minimized, in agreement with previous molecular\ndynamics simulations."
    },
    {
        "anchor": "Free-energy landscape of polymer-crystal polymorphism: Polymorphism rationalizes how processing can control the final structure of a\nmaterial. The rugged free-energy landscape and exceedingly slow kinetics in the\nsolid state have so far hampered computational investigations. We report for\nthe first time the free-energy landscape of a polymorphic crystalline polymer,\nsyndiotactic polystyrene. Coarse-grained metadynamics simulations allow us to\nefficiently sample the landscape at large. The free-energy difference between\nthe two main polymorphs, $\\alpha$ and $\\beta$, is further investigated by\nquantum-chemical calculations. The two methods are in line with experimental\nobservations: they predict $\\beta$ as the more stable polymorph at standard\nconditions. Critically, the free-energy landscape suggests how the $\\alpha$\npolymorph may lead to experimentally observed kinetic traps. The combination of\nmultiscale modeling, enhanced sampling, and quantum-chemical calculations\noffers an appealing strategy to uncover complex free-energy landscapes with\npolymorphic behavior.",
        "positive": "Simulation of polymers in a curved box: Variable range bonding models: We propose new polymer models for Monte Carlo simulation and apply them to a\npolymer chain confined in a relatively thin box which has both curved and flat\nsides, and show that either an ideal or an excluded-volume chain spends more\ntime in the curved region than in the flat region. The ratio of the probability\nof finding a chain in the curved region and in flat region increases\nexponentially with increasing chain length. The results for ideal chains are\nquantitatively consistent with a previously published theory. We find that the\nsame effect appears with excluded-volume chains and a similar scaling relation\ncan be applied to them up to a certain length of the polymer."
    },
    {
        "anchor": "Frustrated Polyelectrolyte Bundles and T=0 Josephson-Junction Arrays: We establish a one-to-one mapping between a model for hexagonal\npolyelectrolyte bundles and a model for two-dimensional, frustrated\nJosephson-junction arrays. We find that the T=0 insulator-to-superconductor\ntransition of the {\\it quantum} system corresponds to a continuous\nliquid-to-solid transition of the condensed charge in the finite temperature\n{\\it classical} system. We find that the role of the vector potential in the\nquantum system is played by elastic strain in the classical system. Exploiting\nthis correspondence we show that the transition is accompanied by a spontaneous\nbreaking of chiral symmetry and that at the transition the polyelectrolyte\nbundle adopts a universal response to shear.",
        "positive": "Dynamics of nanoparticles in polydisperse polymer networks: From free\n  diffusion to hopping: Using molecular dynamics simulations we study the static and dynamic\nproperties of spherical nanoparticles (NPs) embedded in a disordered and\npolydisperse polymer network. Purely repulsive (RNP) as well as weakly\nattractive (ANP) polymer-NP interactions are considered. It is found that for\nboth types of particles the NP dynamics at intermediate and at long times is\ncontrolled by the confinement parameter $C=\\sigma_N/\\lambda$, where $\\sigma_N$\nis the NP diameter and $\\lambda$ is the dynamic localization length of the\ncrosslinks. Three dynamical regimes are identified: i) For weak confinement ($C\n\\lesssim 1$) the NPs can freely diffuse through the mesh; ii) For strong\nconfinement ($C \\gtrsim 1$) NPs proceed by means of activated hopping; iii) For\nextreme confinement ($C \\gtrsim 3$) the mean squared displacement shows on\nintermediate time scales a quasi-plateau since the NPs are trapped by the mesh\nfor very long times. Escaping from this local cage is a process that depends\nstrongly on the local environment, thus giving rise to an extremely\nheterogeneous relaxation dynamics. The simulation data are compared with the\ntwo main theories for the diffusion process of NPs in gels. Both theories give\na very good description of the $C-$dependence of the NP diffusion constant, but\nfail to reproduce the heterogeneous dynamics at intermediate time scales."
    },
    {
        "anchor": "Particle-resolved lattice Boltzmann simulations of 3-dimensional active\n  turbulence: Collective behaviour in suspensions of microswimmers is often dominated by\nthe impact of long-ranged hydrodynamic interactions. These phenomena include\nactive turbulence, where suspensions of pusher bacteria at sufficient densities\nexhibit large-scale, chaotic flows. To study this collective phenomenon, we use\nlarge-scale (up to $N=3\\times 10^6$) particle-resolved lattice Boltzmann\nsimulations of model microswimmers described by extended stresslets. Such\nsystem sizes enable us to obtain quantitative information about both the\ntransition to active turbulence and characteristic features of the turbulent\nstate itself. In the dilute limit, we test analytical predictions for a number\nof static and dynamic properties against our simulation results. For higher\nswimmer densities, where swimmer-swimmer interactions become significant, we\nnumerically show that the length- and timescales of the turbulent flows\nincrease steeply near the predicted finite-system transition density.",
        "positive": "Steady state sedimentation of ultrasoft colloids: The structural and dynamical properties of ultra-soft colloids - star\npolymers - exposed to a uniform external force field are analyzed applying the\nmultiparticle collision dynamics approach, a hybrid coarse-grain mesoscale\nsimulation approach, which captures thermal fluctuations and long-range\nhydrodynamic interactions. In the weak field limit, the structure of the star\npolymer is nearly unchanged, however in an intermediate regime, the radius of\ngyration decreases, in particular transverse to the sedimentation direction. In\nthe limit of a strong field, the radius of gyration increases with field\nstrength. Correspondingly, the sedimentation coefficient increases with\nincreasing field strength, passes through a maximum and decreases again at high\nfield strengths. The maximum value depends on the functionality of the star\npolymer. High field strengths lead to symmetry breaking with trailing, strongly\nstretched polymer arms and a compact star polymer body. In the weak field\nlinear response regime, the sedimentation coefficient follows the scaling\nrelation of a star polymer in terms of functionality and arm length."
    },
    {
        "anchor": "Structure and dynamics of motor-driven microtubule bundles: Connecting the large-scale emergent behaviors of active materials to the\nmicroscopic properties of their constituents is a challenge due to a lack of\ndata on the multiscale dynamics and structure of such systems. We approach this\nproblem by studying the impact of polyethylene glycol, a crowding agent, on\nbundles of microtubules and kinesin-14 molecular motors. Bundles assembled in\nthe presence of either low or high concentrations of polyethylene glycol\ngenerate similar net extensile behaviors. However, as polyethylene glycol\nconcentration is increased, the motion of microtubules in the bundles\ntransition from bi-directional sliding with extension to pure extension with no\nsliding. Small-angle X-ray scattering shows that the transition in microtubule\ndynamics is concomitant with a rearrangement of microtubules in the bundles\nfrom an open hexagonal to a compressed rectangular lattice. These results\ndemonstrate that bundles of microtubules and molecular motors can display\nsimilar mesoscopic extensile behaviors despite having very different internal\nstructures and dynamics.",
        "positive": "Self-optimized biological channels in facilitating the transmembrane\n  movement of charged molecules: We consider an anisotropically two-dimensional diffusion of a charged\nmolecule (particle) through a large biological channel under an external\nvoltage. The channel is modeled as a cylinder of three structure parameters:\nradius, length, and surface density of negative charges located at the channel\ninterior-lining. These charges induce inside the channel a potential that plays\na key role in controlling the particle current through the channel. It was\nshown that to facilitate the transmembrane particle movement the channel should\nbe reasonably self-optimized so that its potential coincides with the resonant\none, resulting in a large particle current across the channel. Observed\nfacilitation appears to be an intrinsic property of biological channels,\nregardless the external voltage or the particle concentration gradient. This\nfacilitation is very selective in the sense that a channel of definite\nstructure parameters can facilitate the transmembrane movement of only\nparticles of proper valence at corresponding temperatures. Calculations also\nshow that the modeled channel is non-Ohmic with the ion conductance which\nexhibits a resonance at the same channel potential as that identified in the\ncurrent."
    },
    {
        "anchor": "Stress in a stimuli-responsive polymer brush: The application of a polymer brush in sensing, actuation, self-folding, among\nothers acutely depends on the tuneable bending of a brush-grafted substrate\ncaused by the stress in the brush. However, the stress in a stimuli-responsive\nbrush has not been investigated. In this work, we study the stress in the\nstimuli-responsive planar polymer brushes of neutral water-soluble polymers\nwith low to very high graft densities using strong stretching theory (SST).\nFirst, SST with the Langevin force-extension relation for a polymer chain is\nextended to the study of stimuli-responsive brushes. Stress profile and other\nproperties of a Poly(N-isopropylacrylamide) (PNIPAm) brush are then obtained\nusing the extended SST and an empirical Flory-Huggins parameter. The model\npredicts that the stress in a PNIPAm brush is inhomogeneous and compressive at\nall temperatures and graft densities. The resultant stress is predicted to\nincrease in magnitude with increasing graft density. Moreover, it decreases in\nmagnitude with an increase in temperature before plateauing in low graft\ndensity brushes. In contrast, its magnitude increases weakly with increasing\ntemperature in high density brushes. This contrasting behavior is traced to the\nminimum in interaction free energy density \\emph{vs} polymer volume fraction\ncurve for PNIPAm solution at a large volume fraction, and stiffening of chains\ndue to finite extensibility. Furthermore, our results indicate that the ability\nto tune the resultant stress by changing temperature diminishes with increasing\ngraft density.",
        "positive": "Patterning of multicomponent elastic shells by Gaussian curvature: Recent findings suggest that shell protein distribution and morphology of\nbacterial microcompartments regulate the chemical fluxes facilitating reactions\nwhich dictate their biological function. We explore how the morphology and\ncomponent patterning are coupled through the competition of mean and Gaussian\nbending energies in multicomponent elastic shells that form three component\nirregular polyhedra. We observe two softer components with lower bending\nrigidities allocate on the edges and vertices while the harder component\noccupies the faces. When subjected to a non-zero interfacial line tension, the\ntwo softer components further separate and pattern into subdomains that are\nmediated by the Gaussian curvature. We find that this degree of fractionation\nis maximized when there is a weaker line tension and when the ratio of bending\nrigidities between the two softer domains $\\approx 2$. Our results reveal a\npatterning mechanism in multicomponent shells that can capture the observed\nmorphologies of bacterial microcompartments and, moreover, can be realized in\nsynthetic vesicles."
    },
    {
        "anchor": "Low-density crystals in charged colloids : Comparison with Yukawa theory: Charged colloids can behave as Yukawa systems, with similar phase behaviour.\nUsing particle- resolved studies, we consider a system with an unusually long\nDebye screening length which forms crystals at low colloid volume fraction\n{\\phi} ~ 0.01. We quantitatively compare this system with the Yukawa model and\nfind that its freezing point is compatible with the theoretical prediction but\nthat the crystal polymorph is not always that expected. In particular we find\nbody-centred cubic crystals where face-centred cubic crystals are expected.",
        "positive": "Kinetic modeling of detonation and effects of negative temperature\n  coefficient: The kinetic modeling and simulation of reactive flows, especially for those\nwith detonation, are further investigated. From the theoretical side, a new set\nof hydrodynamic equations are deduced, where the viscous stress tensor and heat\nflux are replaced by two non-equilibrium quantities that have been defined in\nour previous work. The two non-equilibrium quantities are referred to as\nNonOrganized Momentum Flux (NOMF) and Non-Organized Energy Flux (NOEF),\nrespectively, here. The numerical results of viscous stress (heat flux) have a\ngood agreement with those of NOMF (NOEF) near equilibrium state. Around sharp\ninterfaces, the values of NOMF (NOEF) deviate reasonably from those of viscous\nstress (heat flux). Based on this hydrodynamic model, the relations between the\ntwo non-equilibrium quantities and entropy productions are established. Based\non the discrete Boltzmann model, four kinds of detonation phenomena with\ndifferent reaction rates, including Negative Temperature Coefficient (NTC)\nregime, are simulated and investigated. The differences of the four kinds of\ndetonations are studied from three aspects: hydrodynamic quantities,\nnon-equilibrium quantities and entropy productions."
    },
    {
        "anchor": "A model liquid crystal cell in an RC circuit: A nematic liquid-crystal cell subject to an electric field created by\nelectrodes held at constant potential is modeled as a variable capacitor in an\nRC circuit. The state of the system is characterized in terms of the director\nfield in the cell and the charge on the electrodes. A dynamical system is\ndeveloped that couples director dynamics in the cell (with no fluid flow) and\ncharge dynamics in the circuit. The dynamical equations are derived from\nexpressions for the total potential energy of the system and a dissipation\ninvolving a single rotational viscosity for the director plus Joule heating\nassociated with current in the circuit. An effort is made to quantify effects,\nin particular the widely differing time scales for the processes involved, and\nnumerical illustrations are given. The exercise illuminates aspects of the\nmodeling of equilibrium states of such a system.",
        "positive": "Extended surfaces modulate and can catalyze hydrophobic effects: Interfaces are a most common motif in complex systems. To understand how the\npresence of interfaces affect hydrophobic phenomena, we use molecular\nsimulations and theory to study hydration of solutes at interfaces. The solutes\nrange in size from sub-nanometer to a few nanometers. The interfaces are\nself-assembled monolayers with a range of chemistries, from hydrophilic to\nhydrophobic. We show that the driving force for assembly in the vicinity of a\nhydrophobic surface is weaker than that in bulk water, and decreases with\nincreasing temperature, in contrast to that in the bulk. We explain these\ndistinct features in terms of an interplay between interfacial fluctuations and\nexcluded volume effects---the physics encoded in Lum-Chandler-Weeks theory [J.\nPhys. Chem. B 103, 4570--4577 (1999)]. Our results suggest a catalytic role for\nhydrophobic interfaces in the unfolding of proteins, for example, in the\ninterior of chaperonins and in amyloid formation."
    },
    {
        "anchor": "Granular Flows in a Rotating Drum: the Scaling Law between Velocity and\n  Thickness of the Flow: The flow of dry granular material in a half-filled rotating drum is studied.\nThe thickness of the flowing zone is measured for several rotation speeds, drum\nsizes and beads sizes (size ratio between drum and beads ranging from 47 to\n7400). Varying the rotation speed, a scaling law linking mean velocity vs\nthickness of the flow, $v\\sim h^m$, is deduced for each couple (beads, drum).\nThe obtained exponent $m$ is not always equal to 1, value previously reported\nin a drum, but varies with the geometry of the system. For small size ratios,\nexponents higher than 1 are obtained due to a saturation of the flowing zone\nthickness. The exponent of the power law decreases with the size ratio, leading\nto exponents lower than 1 for high size ratios. These exponents imply that the\nvelocity gradient of a dry granular flow in a rotating drum is not constant.\nMore fundamentally, these results show that the flow of a granular material in\na rotating drum is very sensible to the geometry, and that the deduction of the\n``rheology'' of a granular medium flowing in such a geometry is not obvious.",
        "positive": "Surface tension and a self-consistent theory of soft composite solids\n  with elastic inclusions: The importance of surface tension effects is being recognized in the context\nof soft composite solids, where it is found to significantly affect the\nmechanical properties, such as the elastic response to an external stress. It\nhas recently been discovered that Eshelby's inclusion theory breaks down when\nthe inclusion size approaches the elastocapillary length $L\\equiv\\gamma/E$,\nwhere $\\gamma$ is the inclusion/host surface tension and $E$ is the host\nYoung's modulus. Extending our recent results for liquid inclusions, here we\nmodel the elastic behavior of a non-dilute distribution of isotropic elastic\nspherical inclusions in a soft isotropic elastic matrix, subject to a\nprescribed infinitesimal far-field loading. Within our framework, the composite\nstiffness is uniquely determined by the elastocapillary length $L$, the\nspherical inclusion radius $R$, and the stiffness contrast parameter ${C}$,\nwhich is the ratio of the inclusion to the matrix stiffness. We compare the\nresults with those from the case of liquid inclusions, and we derive an\nanalytical expression for elastic cloaking of the composite by the inclusions.\nRemarkably, we find that the composite stiffness is influenced significantly by\nsurface tension even for inclusions two orders of magnitude more stiff than the\nhost matrix. Finally, we show how to simultaneously determine the surface\ntension and the inclusion stiffness using two independent constraints provided\nby global and local measurements."
    },
    {
        "anchor": "Hopping and microscopic dynamics of ultrasoft particles in cluster\n  crystals: We have investigated the slow dynamics of ultrasoft particles in crystalline\ncluster phases, where point particles interact through the generalized\nexponential potential u(r) = \\epsilon \\exp[-(r/\\sigma)^n], focusing on the\ncluster fcc phase of this model with n=4. In an effort to elucidate how the\nmechanisms of mass transport depend on the microscopic dynamics and in order to\nmimic a realistic scenario in a related experiment we have performed molecular\ndynamics, Brownian dynamics, and Monte Carlo simulations. In molecular dynamics\nsimulations the diffusion of particles proceeds through long-range jumps,\nguided by strong correlations in the momentum direction. In Monte Carlo and\nBrownian dynamics simulations jump events are short-ranged, reflecting the\npurely configurational nature of the dynamics. In contrast to what was found in\nmodels of glass-forming liquids, the effect of Newtonian and stochastic\nmicroscopic dynamics on the long-time relaxation cannot be accounted for by a\ntemperature-independent rescaling of the time units. From the obvious\nqualitative discrepancies in the short time behavior between the three\nsimulation methods and the non-trivial difference in jump length distributions,\nlong time relaxation, and dynamic heterogeneity, we learn that a more complex\nmodeling of the dynamics in realistic systems of ultrasoft colloids is\nrequired.",
        "positive": "Patterning nonisometric origami in nematic elastomer sheets: Nematic elastomers dramatically change their shape in response to diverse\nstimuli including light and heat. In this paper, we provide a systematic\nframework for the design of complex three dimensional shapes through the\nactuation of heterogeneously patterned nematic elastomer sheets. These sheets\nare composed of \\textit{nonisometric origami} building blocks which, when\nappropriately linked together, can actuate into a diverse array of three\ndimensional faceted shapes. We demonstrate both theoretically and\nexperimentally that: 1) the nonisometric origami building blocks actuate in the\npredicted manner, 2) the integration of multiple building blocks leads to\ncomplex multi-stable, yet predictable, shapes, 3) we can bias the actuation\nexperimentally to obtain a desired complex shape amongst the multi-stable\nshapes. We then show that this experimentally realized functionality enables a\nrich possible design landscape for actuation using nematic elastomers. We\nhighlight this landscape through theoretical examples, which utilize large\narrays of these building blocks to realize a desired three dimensional origami\nshape. In combination, these results amount to an engineering design principle,\nwhich we hope will provide a template for the application of nematic elastomers\nto emerging technologies."
    },
    {
        "anchor": "Measurement of the depth-dependent local dynamics in thin polymer films\n  through rejuvenation of ultrastable glasses: We measure the isothermal rejuvenation of stable glass films of poly(styrene)\nand poly(methylmethacrylate). We demonstrate that the propagation of the front\nresponsible for the transformation to a supercooled-liquid state can serve as a\nhighly localized probe of the local supercooled dynamics. We use this\nconnection to probe the depth-dependent relaxation rate with nanometric\nprecision for a series of polystyrene films over a range of temperatures near\nthe bulk glass transition temperature. The analysis shows the spatial extent of\nenhanced surface mobility and reveals the existence of an unexpected large\ndynamical length scale in the system. The results are compared with the\ncooperative-string model for glassy dynamics. The data reveals that the\nfilm-thickness dependence of whole film properties arises only from the volume\nfraction of the near-surface region. While the dynamics at the middle of the\nsamples shows the expected bulk-like temperature dependence, the near-surface\nregion shows very little dependence on temperature.",
        "positive": "A simple model for DNA denaturation: Following Poland and Scheraga, we consider a simplified model for the\ndenaturation transition of DNA. The two strands are modeled as interacting\npolymer chains. The attractive interactions, which mimic the pairing between\nthe four bases, are reduced to a single short range binding term. Furthermore,\nbase-pair misalignments are forbidden, implying that this binding term exists\nonly for corresponding (same curvilinear abscissae) monomers of the two chains.\nWe take into account the excluded volume repulsion between monomers of the two\nchains, but neglect intra-chain repulsion. We find that the excluded volume\nterm generates an effective repulsive interaction between the chains, which\ndecays as $1/r^{d-2}$. Due to this long-range repulsion between the chains, the\ndenaturation transition is first order in any dimension, in agreement with\nprevious studies."
    },
    {
        "anchor": "Synchronized Fractionation and Phase Separation in Binary Colloids: Fractionation is necessary for self-assembly in multicomponent mixtures.\nHere, reversible fractionation and crystallization are realized and studied in\na two-dimensional binary colloids which is supersaturated by enhancing the\nattraction between colloidal particles. As a deep and fast supersaturation\nresults in gels with a uniform distribution of binary particles, a gradual\nquasistatic supersaturating process leads to a two-step crystallization in\nwhich small particles and large particles are fractionated as coexisting\ncrystal and liquid phases respectively. Fractionation occurs as well in the\nquasistatic melting of gel. We show that the synchronized fractionation and\nphase separation arises from the competition between the size-dependent\nrepulsion and the tunable attraction. The results in this study demonstrate a\nrobust mechanism of fractionation via phase separation, and have important\nimplication in understanding the reversible formation of membraneless\norganelles in living cells.",
        "positive": "Self-generated gradients guide cells in their long-distance expeditions: Self-generated gradients (SGG) provide robust steering cues that guide cells\nin their long-distance expeditions during embryonic development, immune\nresponse, and cancer metastasis. Cells generate their own local, dynamic\ngradients by breaking down the broadly distributed attractants in the\nenvironment, which leads to propulsion. How cells sense the environment and the\ninterplay of self-generated force and long-range range chemotactic interactions\ndetermines the collective behavior of cells in vivo is largely unknown. We\ndevelop a theory to provide quantitative insight into how self-generated\nchemotaxis (SGC) steers the collective migration of cells during their\nlong-distance journeys. In an externally imposed gradient, the cells exhibit\nsuper-diffusive motion at time less than persistent time ($\\tau_p$) and exhibit\ndiffusive motion at time $t>\\tau_p$. On the other hand breakdown of\nchemo-attractants influences the density fluctuations and long-range\ncorrelations emerge in the density of chemotactic cells. The cells exhibit\nsuperdiffusive motion at a longtime limit. The SGG provides an effective\nmechanism for long-distance travel compared to an externally imposed gradient.\nOur theory provides a general framework for studying the non-equilibrium\ndynamics of collections of interacting particles."
    },
    {
        "anchor": "Emulsion-templated formation of poly(N-isopropylacrylamide):surfactant\n  mixed shells by thermo-enhanced interfacial complexation: The encapsulation of fragile biomacromolecules is crucial for many\nbiotechnological applications but remains challenging. Interfacial complexation\n(IC) in water-in-oil emulsions turned out to be an efficient process for the\nformation of protective polymer layers at the surface of capsule-precursor\nwater droplets. We propose to further enhance this IC process by introducing\nthermoresponsive poly(N-isopropylacrylamide) (PNIPAM) strands in the\ninterfacial polymer layer. In this work, we implement surfactant-polymer IC in\nwater-in-fluorocarbon oil emulsions between a water-soluble\npoly(L-lysine)-g-poly(N-isopropylacrylamide) cationic copolymer (PLL-g-PNIPAM)\nand an oil-soluble anionic surfactant. We demonstrate that the thermal collapse\ntransition of PNIPAM strands triggers an enrichment of the polymer layer\ninitially formed by IC. This process is leveraged to irreversibly segregate\nwater-soluble nanoparticles in the interfacial polymer layer, resulting in\ngel-like mixed shells. We demonstrate that this thermo-enhancement of\nconventional IC is a promising approach for the formation, strengthening and\nfunctionalization of capsule shells. As implemented in mild conditions,\nthermo-enhanced IC is additionally compatible with the encapsulation of\nproteins, paving the way for new delivery systems of biomacromolecules.",
        "positive": "Rolling of an elastomeric cylinder: a Marangoni like effect in solid: A soft, thin, elastomeric micro-cylinder is induced to roll on a solid\nsubstrate by releasing small quantity of a solvent. The solvent swells the\ncylinder asymmetrically at one side and evaporates out of it from where it is\nexposed to atmosphere. Because of inhomogeneous swelling, the cylinder bends\nbut tends to straighten out following evaporation of the solvent. Balance of\nthese two opposing effects induces the static state of the cylinder to\neventually bifurcate to a dynamic state of rolling. Similar to marangoni effect\nin liquid, the rolling motion of cylinder is driven and sustained by the\ncurvature of the cylinder. The rolling velocity increases linearly with\ncurvature of the bent cylinder which ceases to locomote as the curvature\ndiminishes below a threshold limit. Similar to marangoni effect, the rolling\nvelocity increases also with temperature of the substrate and surroundings. A\nscaling relation derived for the rolling velocity captures all these\nobservations."
    },
    {
        "anchor": "Stationary shapes of deformable particles moving at low Reynolds numbers: Lecture Notes of the Summer School ``Microswimmers -- From Single Particle\nMotion to Collective Behaviour'', organised by the DFG Priority Programme SPP\n1726 (Forschungszentrum J{\\\"{u}}lich, 2015).",
        "positive": "Nonlocal diffusion currents at the nanoscale: An integro-differential expression for the diffusion current of the\nimpurities diffusing by the mechanism of bound impurity-defect pairs has been\nderived. The ensuing nonlocal diffusion equation generalizes the existing\ntheories of diffusion by the pair mechanism in unbounded systems with\nhomogeneous defect distributions on the systems with boundaries and variable\ndefect concentration. It has been established that the nonlocality manifests\nitself only at short diffusion times while at large times, in particular, under\nthe stationary conditions, the predictions of the nonlocal theory would\ncoincide with existing approaches based on local diffusion currents.\nPossibilities of experimental verification of the nonlocal theory have been\nsuggested. In particular, the explanation of the uphill diffusion in silicon by\nthe pair drag can be tested within slightly modified conventional experimental\nsetups. Also, it has been shown that in the nonlocal theory the impurity\nsegregation profile caused by the drag should differ at the initial stage of\nevolution from the predictions of the local theories. Because the segregation\ninfluences mechanical, corrosive, and electronic properties of materials, the\nnonlocal character of the pair diffusion may have important implications for\nnanostructured materials."
    },
    {
        "anchor": "Adhesion dynamics of confined membranes: We report on the modeling of the dynamics of confined lipid membranes. We\nderive a thin film model in the lubrication limit which describes an\ninextensible liquid membrane with bending rigidity confined between two\nadhesive walls. The resulting equations share similarities with the\nSwift-Hohenberg model. However, inextensibility is enforced by a time-dependent\nnonlocal tension. Depending on the excess membrane area available in the\nsystem, three different dynamical regimes, denoted as A, B and C, are found\nfrom the numerical solution of the model. In regime A, membranes with small\nexcess area form flat adhesion domains and freeze. Such freezing is interpreted\nby means of an effective model for curvature-driven domain wall motion. The\nnonlocal membrane tension tends to a negative value corresponding to the linear\nstability threshold of flat domain walls in the Swift-Hohenberg equation. In\nregime B, membranes with intermediate excess areas exhibit endless coarsening\nwith coexistence of flat adhesion domains and wrinkle domains. The tension\ntends to the nonlinear stability threshold of flat domain walls in the\nSwift-Hohenberg equation. The fraction of the system covered by the wrinkle\nphase increases linearly with the excess area in regime B. In regime C,\nmembranes with large excess area are completely covered by a frozen\nlabyrinthine pattern of wrinkles. As the excess area is increased, the tension\nincreases and the wavelength of the wrinkles decreases. For large membrane\narea, there is a crossover to a regime where the extrema of the wrinkles are in\ncontact with the walls. In all regimes after an initial transient, robust\nlocalised structures form, leading to an exact conservation of the number of\nadhesion domains.",
        "positive": "Glasses in Colloidal Systems. Attractive Interactions and Gelation: In this chapter, a study of the glass transitions in colloidal systems is\npresented, in connection with gelation, mainly from theoretical and simulation\nresults. Mode Coupling Theory, which anticipated the existence of attraction\ndriven glasses, is reviewed, and its predictions concerning attractive glasses\ndiscussed. Results from computer simulations will be presented for different\nmodels and the predictions of the theory will be tested. Starting from high\ndensity, where reasonable agreement is found, the study will be extended to low\ndensity, where new modes for the decay of density correlation functions appear.\nIn all cases, the results will be also be brought into connection with\nexperiments, and we will conclude with a discussion of the present\nunderstanding of the mechanisms leading to gelation."
    },
    {
        "anchor": "Fluctuating Topological Defects in 2D Liquids: Heterogeneous Motion and\n  Noise: We measure the defect density as a function of time at different temperatures\nin simulations of a two dimensional system of interacting particles. Just above\nthe solid to liquid transition temperature, the power spectrum of the defect\nfluctuations shows a 1/f signature, which crosses over to a white noise\nsignature at higher temperatures. When 1/f noise is present, the 5-7 defects\npredominately form string like structures, and the particle trajectories show a\n1D correlated motion that follows the defect strings. At higher temperatures\nthis heterogeneous motion is lost. We demonstrate this heterogeneity both in\nsystems interacting with a short ranged screened Coulomb interaction, as well\nas in systems with a long range logarithmic interaction between the particles.",
        "positive": "Microstructure and yielding of capillary force induced gel: We have investigated the rheology and structure of a gel formed from a\nmixture of non-Brownian particles and two immiscible liquids. The suspension of\nparticles in a liquid undergoes gelation upon the addition of a small content\nof second, wetting liquid which forms liquid bridges between particles leading\nto a sample spanning network. The rheology of this gel primarily exhibits a\nyield stress at low shear rates followed by a linear variation of shear stress\nat high shear rates. The apparent yield stress extracted from the flow curves\nincreases rapidly with volume fraction of second liquid before saturation,\nwhile it exhibits a monotonic increase with increasing particle concentration.\nRescaling of the yield stress curves using suitable shift factors results in an\nempirical expression for the yield stress showing squared dependence on liquid\nfraction and a rapid increase with particle fraction above a certain value,\nboth combined in a highly nonlinear manner. The microstructural variations with\nchanging secondary liquid content and particle fractions are captured using\nthree dimensional X-ray tomography technique. The microstructure is observed to\nshow increased local compactness with increased liquid content and increased\nspatial homogeneity with increased particle fractions. The images from X-ray\ntomography are analysed to obtain the distributions of particle-particle bonds\n(coordination number) in the system which serve to explain the observed yield\nstress behavior in a qualitative manner."
    },
    {
        "anchor": "Yield Stress and Compliance in Active Cell Monolayers: The rheology of biological tissue plays an important role in many processes,\nfrom organ formation to cancer invasion. Here, we use a multi-phase field model\nof motile cells to simulate active microrheology within a tissue monolayer.\nWhen unperturbed, the tissue exhibits a transition between a solid-like state\nand a fluid-like state tuned by cell motility and deformability - the ratio of\nthe energetic costs of steric cell-cell repulsion and cell surface tension.\nWhen perturbed, solid tissues exhibit yield-stress behavior, with a threshold\nforce for the onset of motion of a probe particle that vanishes upon\napproaching the solid-to-liquid transition. This onset of motion is\nqualitatively different in the low and high deformability regimes. At high\ndeformability, the tissue is amorphous when solid, it responds compliantly to\ndeformations, and the probe transition to motion is smooth. At low\ndeformability, the monolayer is more ordered translationally and stiffer, and\nthe onset of motion appears discontinuous. Our results suggest that cellular or\nnanoparticle transport in different types of tissues can be fundamentally\ndifferent, and point to ways in which it can be controlled.",
        "positive": "Transition to Centrifugal Particle Motion in Rotating Drums: The dynamics and the transition to the centrifugal regime are studied\nanalytically and numerically for particles in rotating drum. The importance of\nthe particle-wall friction coefficient is demonstrated by studying first the\nmotion of one non-rotating particle where three different regimes are found in\nthe transition to the centrifugal motion. When a few rotating particles are\nconsidered, they behave similarly to one non-rotating particle in the low\nfriction limit. A critical particle number is necessary to reach the\ncentrifugal regime for which an analytic expression is derived in the limit of\nnegligible inter-particle friction."
    },
    {
        "anchor": "Melting upon cooling and freezing upon heating: Fluid-solid phase\n  diagram for Svejk-Hasek model of dimerizing hard spheres: A simple model of dimerizing hard spheres with highly nontrivial fluid-solid\nphase behaviour is proposed. The model is studied using the recently proposed\nresummed thermodynamic perturbation theory for central force (RTPT-CF)\nassociating potentials. The phase diagram has the fluid branch of the\nfluid-solid coexistence curve located at a temperatures lower than those of the\nsolid branch. This unusual behaviour is related to the strong dependence of the\nsystem excluded volume on the temperature, which for the model at hand\ndecreases with increasing temperature. This effect can be also seen for a wide\nfamily of fluid models with an effective interaction that combines short range\nattraction and repulsion at a larger distance. We expect that for sufficiently\nhigh repulsive barrier, such systems may show similar phase behaviour.",
        "positive": "Granular Segregation in Tapered Rotating Drums: We study the granular segregation in a tapered rotating drum by means of\nsimulations. In this geometry, both radial and axial segregation appear, the\nstrength of which depends on the filling fraction. We study the effect of the\ndrum's tapering angle on the segregation speed and show that, coherently with\nseveral recent studies, the axial segregation is due to the combined effect of\nthe radial segregation and the shape of the drum. We show that the axial\nsegregation behaves in a way analogous to the one found in chute flows, and\ncorresponds to previous theories for shallow gravity driven surface flows with\ndiffusion. By means of this analogy, we show that tapered drums could be the\nsimplest experimental set-up to obtain the free parameters of the theory."
    },
    {
        "anchor": "Ground state clusters for short-range attractive and long-range\n  repulsive potentials: We report calculations of the ground state energies and geometries for\nclusters of different sizes (up to 80 particles), where individual particles\ninteract simultaneously via a short-ranged attractive -modeled with a\ngeneralization of the Lennard-Jones potential- and a long-ranged repulsive\nYukawa potential. We show that, for specific choices of the parameters of the\nrepulsive potential, the ground state energy per particle has a minimum at a\nfinite cluster size. For these values of the parameters in the thermodynamic\nlimit, at low temperatures and small packing fractions -where clustering is\nfavored and cluster-cluster interactions can be neglected- thermodynamically\nstable cluster phases can be formed. The analysis of the ground state\ngeometries shows that the spherical shape is marginally stable. In the majority\nof the studied cases, we find that, above a certain size, ground state clusters\npreferentially grow almost in one dimension.",
        "positive": "Self-Organized Velocity Pulses of Dense Colloidal Suspensions in\n  Microchannel Flow: We present a numerical study of dense colloidal suspensions in\npressure-driven microchannel flow in two dimensions. The colloids are modeled\nas elastic and frictional spheres suspended in a Newtonian fluid, which we\nsimulate using the method of multi-particle collision dynamics. The model\nreproduces periodic velocity and density pulse trains, traveling upstream in\nthe microchannel, which are found in experiments conducted by L. Isa et al.\n[Phys. Rev. Lett. 102, 058302 (2009)]. We show that colloid-wall friction and\nthe resultant force chains are crucial for the formation of these pulses. With\nincreasing colloid density first solitary jams occur, which become periodic\npulse trains at intermediate densities and unstable solitary pulses at high\ndensities. We formulate a phenomenological continuum model and show how these\nspatio-temporal flow and density profiles can be understood as homoclinic and\nperiodic orbits in traveling-wave equations."
    },
    {
        "anchor": "Evaporative self-assembly of motile droplets: Self-assembly is the underlying building principle of biological systems and\nrepresents a promising approach for the future of manufacturing, but the yields\nare often limited by undesirable metastable states. Meanwhile, annealing\nmethods have long been an important means to guide complex systems towards\noptimal states. Despite their importance, there have been few attempts to\nexperimentally visualize the microscopic dynamics that occur during annealing.\nHere, we present an experimental system that enables the study of interacting\nmany-body dynamics by exploiting the physics of multi-droplet evaporation on a\nprescribed lattice network. Ensembles of motile binary droplets are seeded into\na hexagonal lattice template where interactions are mediated through the vapor\nphase and can be manipulated through the application of a global gravitational\nfield. We show that for finite systems (61 droplets) the interacting droplets\nhave an effective long-ranged interaction that results in the formation of\nfrustrated, metastable states. Application of a periodic, global gravitational\nfield can drive the system through a non-equilibrium phase transition\nseparating phase-locked synchronization from interaction-dominated behavior.\nFinally, we directly visualize field-driven annealing that leads to terminal\nstates that are less frustrated. Overall, our results represent a new platform\nfor studying many-body physics with long-ranged interactions, enabling the\ndesign of field-based control strategies for programming the self-assembly of\ncomplex many-body systems.",
        "positive": "Statistical Mechanics of Jammed Matter: A thermodynamic formulation of jammed matter is reviewed. Experiments and\nsimulations of compressed emulsions and granular materials are then used to\nprovide a foundation for the thermodynamics."
    },
    {
        "anchor": "Phase separation kinetics of block copolymer melts confined under moving\n  parallel walls: a DPD study: We use dissipative particle dynamics (DPD) simulations to study the effect of\nshear on domain morphology and kinetics of microphase separating critical\ndiblock copolymer (BCP) bulk melts. The melt is confined within two parallel\nsolid walls at the top and bottom of the simulation box. The shear is induced\nby allowing the walls to move in a direction with a specific velocity. We\nexplore the following cases: (i) walls are fixed, (ii) only the top wall moves,\n(iii) both walls move in the same direction, and (iv) both walls move in\nopposite directions. After the temperature quench, we monitor the effect of\nshear on evolution morphology, the scaling behavior of the system, and the\ncharacteristic length scale and growth. The characteristic length scale follows\ntypical power-law behavior at early times and saturates at late times when both\nwalls are fixed. The length scale changes significantly with shear caused by\nwall velocities. The usual lamellar morphology, which is not achieved for case\n1 within the considered simulation time steps, is noticed much earlier for the\nnonzero wall velocity cases. Specifically, it is seen much before in case 4\nthan in the other cases. We find that the shear viscosity decreases\n(shear-thinning) with wall velocity (shear rate) for all the cases at a given\ncoarsening time. Overall, we report the influence rule of shear rates on\nmicrophase separation kinetics of BCP melts. This study can provide a scheme to\nanticipate and design anisotropic microstructures under the application of\nexternally controlled wall shear that may further guide in producing the\nvarious composite materials with superior mechanical and physical properties.",
        "positive": "The nonlinear buckling behavior of a complete spherical shell under\n  uniform external pressure and homogenous natural curvature: In this work, we consider the stability of a spherical shell under combined\nloading from a uniform external pressure and a homogenous natural curvature.\nNon-mechanical stimuli, such as one that tends to modify the rest curvature of\nan elastic body, are prevalent in a wide range of natural and engineered\nsystems, and may occur due to thermal expansion, changes in pH, differential\nswelling, and differential growth. Here, we investigate how the presence of\nboth an evolving natural curvature and an external pressure modifies the\nstability of a complete spherical shell. We show that due to a mechanical\nanalogy between pressure and curvature, positive natural curvatures can\nseverely destabilize a thin shell, while negative natural curvatures can\nstrengthen the shell against buckling, providing the possibility to design\nshells that buckle at or above the theoretical limit for pressure alone, i.e. a\nknock-up factor. These results extend directly from the classical analysis of\nthe stability of shells under pressure, and highlight the important role that\nnon-mechanical stimuli can have on modifying the the membrane state of stress\nin a thin shell."
    },
    {
        "anchor": "Thermal (in)stability of type I collagen fibrils: We measured Young's modulus at temperatures ranging from 20 to 100 ^{\\circ}$C\nfor a collagen fibril taken from rat's tendon. The hydration change under\nheating and the damping decrement were measured as well. At physiological\ntemperatures $25-45^{\\circ}$C Young's modulus decreases, which can be\ninterpreted as instability of collagen. For temperatures between\n$45-80^{\\circ}$C Young's modulus first stabilizes and then increases with\ndecreasing the temperature. The hydrated water content and the damping\ndecrement have strong maxima in the interval $70-80^{\\circ}$C indicating on\ncomplex inter-molecular structural changes in the fibril. All these effects\ndisappear after heat-denaturating the sample at $120^\\circ$C. Our main result\nis a five-stage mechanism by which the instability of a single collagen at\nphysiological temperatures is compensated by the interaction between collagen\nmolecules within the fibril.",
        "positive": "Mesoscopic analysis of Gibbs' criterion for sessile nanodroplets on\n  trapezoidal substrates: By taking into account precursor films accompanying nanodroplets on\ntrapezoidal substrates we show that on a mesoscopic level of description one\ndoes not observe the phenomenon of liquid-gas-substrate contact line pinning at\nsubstrate edges. This phenomenon is present in a macroscopic description and\nleads to non-unique contact angles which can take values within a range\ndetermined by the so-called Gibbs' criterion. Upon increasing the volume of the\nnanodroplet the apparent contact angle evaluated within the mesoscopic approach\nchanges continuously between two limiting values fulfilling Gibbs' criterion\nwhile the contact line moves smoothly across the edge of the trapezoidal\nsubstrate. The spatial extent of the range of positions of the contact line,\ncorresponding to the variations of the contact angle between the values given\nby Gibbs' criterion, is of the order of ten fluid particle diameters."
    },
    {
        "anchor": "Solvent Driven Formation of Bolaamphiphilic Vesicles: We show that a spontaneous bending of single layer bolaamphiphiles results\nfrom the frustration due to the competition between core-core and tail-solvent\ninteractions. We find that spherical vesicles are stable under rather general\nassumptions on these interactions described within the Flory-Huggins theory. We\nconsider also the deformation of the vesicles in an external magnetic field\nthat has been recently experimentally observed.",
        "positive": "Ab initio Molecular Dynamics Study of Glycine Intramolecular Proton\n  Transfer in Water: We use ab initio molecular dynamics simulations to quantify structural and\nthermodynamic properties of a model proton transfer reaction that converts a\nneutral glycine molecule, stable in the gas phase, to the zwitterion that\npredominates in aqueous solution. We compute the potential of mean force\nassociated with the direct intramolecular proton transfer event in glycine.\nStructural analyses show that the average hydration number Nw of glycine is not\nconstant along the reaction coordinate, but rather progresses from Nw=5 in the\nneutral molecule to Nw=8 for the zwitterion. We report the free energy\ndifference between the neutral and charged glycine molecules, and the free\nenergy barrier to proton transfer. Finally, we identify approximations inherent\nin our method and estimate corresponding corrections to our reported\nthermodynamic predictions."
    },
    {
        "anchor": "Tuning the scattering length with an optically induced Feshbach\n  resonance: We demonstrate optical tuning of the scattering length in a Bose-Einstein\ncondensate as predicted by Fedichev {\\em et al.} [Phys. Rev. Lett. {\\bf 77},\n2913 (1996)]. In our experiment atoms in a $^{87}$Rb condensate are exposed to\nlaser light which is tuned close to the transition frequency to an excited\nmolecular state. By controlling the power and detuning of the laser beam we can\nchange the atomic scattering length over a wide range. In view of laser-driven\natomic losses we use Bragg spectroscopy as a fast method to measure the\nscattering length of the atoms.",
        "positive": "Calculations of the Structure of Basin Volumes for Mechanically Stable\n  Packings: There are a finite number of distinct mechanically stable (MS) packings in\nmodel granular systems composed of frictionless spherical grains. For typical\npacking-generation protocols employed in experimental and numerical studies,\nthe probabilities with which the MS packings occur are highly nonuniform and\ndepend strongly on parameters in the protocol. Despite intense work, it is\nextremely difficult to predict {\\it a priori} the MS packing probabilities, or\neven which MS packings will be the most versus the least probable. We describe\na novel computational method for calculating the MS packing probabilities by\ndirectly measuring the volume of the MS packing `basin of attraction', which we\ndefine as the collection of initial points in configuration space at {\\it zero\npacking fraction} that map to a given MS packing by following a particular\ndynamics in the density landscape. We show that there is a small core region\nwith volume $V^c_n$ surrounding each MS packing $n$ in configuration space in\nwhich all initial conditions map to a given MS packing. However, we find that\nthe MS packing probabilities are very weakly correlated with core volumes.\nInstead, MS packing probabilities obtained using initially dilute\nconfigurations are determined by complex geometric features of the basin of\nattraction that are distant from the MS packing."
    },
    {
        "anchor": "Persistent structures in a 3D dynamical system with solid and fluid\n  regions: Remarkably persistent mixing and non-mixing regions (islands) are observed to\ncoexist in a three-dimensional dynamical system where randomness is expected.\nThe track of an x-ray opaque particle in a spherical shell half-filled with dry\nnon-cohesive particles and periodically rotated about two axes reveals\ninterspersed structures that are spatially complex and vary non-trivially with\nthe rotation angles. The geometric skeleton of the structures forms from the\nsubtle interplay between fluid-like mixing by stretching-and-folding, and\nsolids mixing by cutting-and-shuffling, which is described by the mathematics\nof piecewise isometries. In the physical system, larger islands predicted by\nthe cutting-and-shuffling model alone can persist despite the presence of\nstretching-and-folding flows and particle-collision-driven diffusion, while\npredicted smaller islands are not observed. By uncovering the synergy of\nsimultaneous fluid and solid mixing, we point the way to a more fundamental\nunderstanding of advection driven mixing in materials with both solid and\nflowing regions.",
        "positive": "Particle pairs and trains in inertial microfluidics: Staggered and linear multi-particle trains constitute characteristic\nstructures in inertial microfluidics. Using lattice-Boltzmann simulations, we\ninvestigate their properties and stability, when flowing through microfluidic\nchannels. We confirm the stability of cross-streamline pairs by showing how\nthey contract or expand to their equilibrium axial distance. In contrast,\nsame-streamline pairs quickly expand to a characteristic separation but even at\nlong times slowly drift apart. We reproduce the distribution of particle\ndistances with its characteristic peak as measured in experiments.\n  Staggered multi-particle trains initialized with an axial particle spacing\nlarger than the equilibrium distance contract non-uniformly due to collective\ndrag reduction. Linear particle trains, similar to pairs, rapidly expand\ntowards a value about twice the equilibrium distance of staggered trains and\nthen very slowly drift apart non-uniformly. Again, we reproduce the statistics\nof particle distances and the characteristic peak observed in experiments.\nFinally, we thoroughly analyze the damped displacement pulse traveling as a\nmicrofluidic phonon through a staggered train and show how a defect strongly\ndamps its propagation."
    },
    {
        "anchor": "Self-organization and shape change by active polarization in nematic\n  droplets: Active forces occurring within cells can drive crucial biological processes\nthat involve spontaneous organization and shape change, such as cell division.\nMotivated by recent in vitro experiments of nematic droplets of cytoskeletal\nfilaments and motors that self-organize and divide, we present a minimal\nhydrodynamic model that combines the nonequilibrium kinetics of motor-filament\ninteractions with equilibrium nematic phase separation. The motors organize\nwithin droplets and structure filaments into polarized aster defects. At large\nmotor activity, they can even deform or divide the droplet, or form multi-aster\nchains of droplets. Our predicted phase diagram recapitulates these\nexperimentally observed shapes.",
        "positive": "Self-assembly of the decagonal quasicrystalline order in simple\n  three-dimensional systems: For a three dimensional system we answer two questions, how simple a particle\nsystem might be to show the quasicrystal order and, what system features are\nthe most important for quasicrystal formation? One-component system of\nparticles with isotropic pair interaction is one of the simplest ones. We show\nthat such system may be driven to three-dimensional decagonal (10-fold)\nquasicrystalline state just by purely repulsive, isotropic and monotonic\ninteraction pair potential with two characteristic length scales; no attraction\nis needed. The second question we answer defining universal (nearly independent\nfrom the shape of the pair potential) effective integral parameters related to\nthe first peak of the radial distribution function. The universality is\nillustrated by demonstrating the quasicrystalline order for a number of\nparticle systems with absolutely different interaction potentials, both purely\nrepulsive and attractive, but with the same effective integral parameters.\nSimple models like we study qualitatively describe effective interaction in\nmolecular liquids, soft matter systems and metallic alloys for which\nquasicrystals have been experimentally observed."
    },
    {
        "anchor": "Optimizing Brownian escape rates by potential shaping: Brownian escape is key to a wealth of physico-chemical processes, including\npolymer folding, and information storage. The frequency of thermally activated\nenergy barrier crossings is assumed to generally decrease exponentially with\nincreasing barrier height. Here, we show experimentally that higher, fine-tuned\nbarrier profiles result in significantly enhanced escape rates in breach of the\nintuition relying on the above scaling law, and address in theory the\ncorresponding conditions for maximum speed-up. Importantly, our barriers end on\nthe same energy on which they start. For overdamped dynamics, the achievable\nboost of escape rates is, in principle, unbounded so that the barrier\noptimization has to be regularized. We derive optimal profiles under two\ndifferent regularizations, and uncover the efficiency of N-shaped barriers. We\nthen demonstrate the viability of such a potential in automated microfluidic\nBrownian dynamics experiments using holographic optical tweezers and achieve a\ndoubling of escape rates compared to unhindered Brownian motion. Finally, we\nshow that this escape rate boost extends into the low-friction inertial regime.",
        "positive": "Hydro-Responsive Curling of the Resurrection Plant Selaginella\n  lepidophylla: The spirally arranged stems of the spikemoss Selaginella lepidophylla, an\nancient resurrection plant, compactly curl into a nest-ball shape upon\ndehydration. Due to its spiral phyllotaxy, older outer stems on the plant\ninterlace and envelope the younger inner stems forming the plant centre. Stem\ncurling is a morphological mechanism that limits photoinhibitory and thermal\ndamages the plant might experience in arid environments. Here, we investigate\nthe distinct conformational changes of outer and inner stems of S. lepidophylla\ntriggered by dehydration. Outer stems bend into circular rings in a relatively\nshort period of desiccation, whereas inner stems curl slowly into spirals due\nto hydro-actuated strain gradient along their length. This arrangement eases\nboth the tight packing of the plant during desiccation and its fast opening\nupon rehydration. The insights gained from this work shed light on the\nhydro-responsive movements in plants and might contribute to the development of\ndeployable structures with remarkable shape transformations in response to\nenvironmental stimuli."
    },
    {
        "anchor": "Reinforcement learning of optimal active particle navigation: The development of self-propelled particles at the micro- and the nanoscale\nhas sparked a huge potential for future applications in active matter physics,\nmicrosurgery, and targeted drug delivery. However, while the latter\napplications provoke the quest on how to optimally navigate towards a target,\nsuch as e.g. a cancer cell, there is still no simple way known to determine the\noptimal route in sufficiently complex environments. Here we develop a machine\nlearning-based approach that allows us, for the first time, to determine the\nasymptotically optimal path of a self-propelled agent which can freely steer in\ncomplex environments. Our method hinges on policy gradient-based deep\nreinforcement learning techniques and, crucially, does not require any reward\nshaping or heuristics. The presented method provides a powerful alternative to\ncurrent analytical methods to calculate optimal trajectories and opens a route\ntowards a universal path planner for future intelligent active particles.",
        "positive": "Particle-scale origins of shear strength in granular media: The shear strength of cohesionless granular materials is generally attributed\nto the compactness or anisotropy of their microstructure. An open issue is how\nsuch compact or anisotropic microstructures, and thus the shear strength,\ndepend on the particle properties. We first recall the role of fabric and force\nanisotropies with respect to the critical-state shear stress. Then, a model of\naccessible geometrical states in terms of particle connectivity and contact\nanisotropy is presented. This model incorporates in a simple way the fact that,\ndue to steric exclusions, the highest levels of connectivity and anisotropy\ncannot be reached simultaneously, a property that affects seriously the shear\nstrength. We also analyze the force anisotropy in the light of the specific\nrole of weak forces in sustaining strong force chains and thus the main\nmechanism that underlies anisotropic force patterns. Finally, we briefly\ndiscuss the effect of interparticle friction, particle shape, size\npolydispersity and adhesion."
    },
    {
        "anchor": "Topological rearrangements and stress fluctuations in\n  quasi-two-dimensional hopper flow of emulsions: We experimentally study the shear flow of oil-in-water emulsion droplets in a\nthin sample chamber with a hopper shape. In this thin chamber, the droplets are\nquasi-2D in shape. The sample is at an area fraction above jamming and forced\nto flow with a constant flux rate. Stresses applied to a droplet from its\nneighbors deform the droplet outline, and this deformation is quantified to\nprovide an ad hoc measure of the stress. As the sample flows through the hopper\nwe see large fluctuations of the stress, similar in character to what has been\nseen in other flows of complex fluids. Periods of time with large decreases in\nstress are correlated with bursts of elementary rearrangement events (\"T1\nevents\" where four droplets rearrange). More specifically, we see a local\nrelationship between these observations: a T1 event decreases the inter-droplet\nforces up to 3 droplet diameters away from the event. This directly connects\nmicroscopic structural changes to macroscopic fluctuations, and confirms\ntheoretical pictures of local rearrangements influencing nearby regions. These\nlocal rearrangements are an important means of reducing and redistributing\nstresses within a flowing material.",
        "positive": "Kerr constant of vesicle-like droplets: The Kerr effect on vesicle-like droplets is described. We give a simple\nderivation of the Kerr constant for a dielectric fluid droplet immersed in\nanother fluid, assuming that the droplet in an electric field becomes a prolate\nellipsoid. The Kerr constant is evaluated also for a droplet covered by a\nmembrane of finite thickness. The latter result differs significantly from the\nresult by E. van der Linden et al. [Physica A 156}, 130 (1989)]. Due to the\ndifference the bending rigidity constant of the surface layer extracted from\ntheir experiments on droplet microemulsions should be increased about two\ntimes."
    },
    {
        "anchor": "Validity of the Rosenfeld relationship: A comparative study of the\n  network forming NTW model and other simple liquids: In this paper we explore the validity of the Rosenfeld and the Dzugutov\nrelation for the Lennard-Jones (LJ) system, its repulsive counterpart, the WCA\nsystem and a network forming liquid, the NTW model. We find that for all the\nsystems both the relations are valid at high temperature regime with an\nuniversal exponent close to 0.8. Similar to that observed for the simple\nliquids, the LJ and the WCA systems show a breakdown of the scaling laws at the\nlow temperature regime. However for the NTW model, which is a simple liquid,\nthese scaling laws are valid even at lower temperature regime similar to that\nfound for ionic melts. Thus we find that the NTW model has mixed\ncharacteristics of simple liquids and ionic melts. Our study further reveals a\nquantitative relationship between the Rosenfeld and the Arrhenius relations.\nFor strong liquids, the validity of the Rosenfeld relation in the low\ntemperature regime is connected to it following the Arrhenius behaviour in that\nregime. Finally we explore the role of pair entropy and residual multiparticle\nentropy in the dynamics as a function of fragility of the systems.",
        "positive": "A molecular perspective on the limits of life: Enzymes under pressure: From a purely operational standpoint, the existence of microbes that can grow\nunder extreme conditions, or \"extremophiles\", leads to the question of how the\nmolecules making up these microbes can maintain both their structure and\nfunction. While microbes that live under extremes of temperature have been\nheavily studied, those that live under extremes of pressure have been\nneglected, in part due to the difficulty of collecting samples and performing\nexperiments under the ambient conditions of the microbe. However, thermodynamic\narguments imply that the effects of pressure might lead to different organismal\nsolutions than from the effects of temperature. Observationally, some of these\nsolutions might be in the condensed matter properties of the intracellular\nmilieu in addition to genetic modifications of the macromolecules or repair\nmechanisms for the macromolecules. Here, the effects of pressure on enzymes,\nwhich are proteins essential for the growth and reproduction of an organism,\nand some adaptations against these effects are reviewed and amplified by the\nresults from molecular dynamics simulations. The aim is to provide biological\nbackground for soft matter studies of these systems under pressure."
    },
    {
        "anchor": "Vortex lattice stability and phase coherence in three-dimensional\n  rapidly rotating Bose condensates: We establish the general equations of motion for the modes of a vortex\nlattice in a rapidly rotating Bose-Einstein condensate in three dimensions,\ntaking into account the elastic energy of the lattice and the vortex line\nbending energy. As in two dimensions, the vortex lattice supports Tkachenko and\ngapped sound modes. In contrast, in three dimensions the Tkachenko mode\nfrequency at long wavelengths becomes linear in the wavevector for any\npropagation direction out of the transverse plane. We compute the correlation\nfunctions of the vortex displacements and the superfluid order parameter for a\nhomogeneous Bose gas of bounded extent in the axial direction. At zero\ntemperature the vortex displacement correlations are convergent at large\nseparation, but at finite temperatures, they grow with separation. The growth\nof the vortex displacements should lead to observable melting of vortex\nlattices at higher temperatures and somewhat lower particle number and faster\nrotation than in current experiments. At zero temperature a system of large\nextent in the axial direction maintains long range order-parameter correlations\nfor large separation, but at finite temperatures the correlations decay with\nseparation.",
        "positive": "Linear response of a grafted semiflexible polymer to a uniform force\n  field: We use the worm-like chain model to analytically calculate the linear\nresponse of a grafted semiflexible polymer to a uniform force field. The result\nis a function of the bending stiffness, the temperature, the total contour\nlength, and the orientation of the field with respect to that of the grafted\nend. We also study the linear response of a worm-like chain with a periodic\nalternating sequence of positive and negative charges. This can be considered\nas a model for a polyampholyte with intrinsic bending siffness and negligible\nintramolecular interactions. We show how the finite intrinsic persistence\nlength affects the linear response to the external field."
    },
    {
        "anchor": "Rheological properties of sheared vesicle and cell suspensions: Numerical simulations of vesicle suspensions are performed in two dimensions\nto study their dynamical and rheological properties. An hybrid method is\nadopted, which combines a mesoscopic approach for the solvent with a\ncurvature-elasticity model for the membrane. Shear flow is induced by two\ncounter-sliding parallel walls, which generate a linear flow profile. The flow\nbehavior is studied for various vesicle concentrations and viscosity ratios\nbetween the internal and the external fluid. Both the intrinsic viscosity and\nthe thickness of depletion layers near the walls are found to increase with\nincreasing viscosity ratio.",
        "positive": "Fractional Stokes-Einstein and Debye-Stokes-Einstein relations in a\n  network forming liquid: We study the breakdown of the Stokes-Einstein (SE) and Debye-Stokes-Einstein\n(DSE) relations for translational and rotational motion in a prototypical model\nof a network-forming liquid, the ST2 model of water. We find that the emergence\nof ``fractional'' SE and DSE relations at low temperature is ubiquitous in this\nsystem, with exponents that vary little over a range of distinct physical\nregimes. We also show that the same fractional SE relation is obeyed by both\nmobile and immobile dynamical heterogeneities of the liquid."
    },
    {
        "anchor": "Optical patterning of magnetic domains and defects in ferromagnetic\n  liquid crystal colloids: A promising approach in designing composite materials with unusual physical\nbehavior combines solid nanostructures and orientationally ordered soft matter\nat the mesoscale. Such composites not only inherit properties of their\nconstituents but also can exhibit emergent behavior, such as ferromagnetic\nordering of colloidal metal nanoparticles forming mesoscopic magnetization\ndomains when dispersed in a nematic liquid crystal. Here we demonstrate the\noptical patterning of domain structures and topological defects in such\nferromagnetic liquid crystal colloids, which allows for altering their response\nto magnetic fields. Our findings reveal the nature of the defects in this soft\nmatter system which is different as compared to non-polar nematics and\nferromagnets alike.",
        "positive": "Use of ultrasound attenuation spectroscopy to determine the size\n  distribution of clay tactoids in aqueous suspensions: The dispersion processes of aqueous samples of clay are studied using\nultrasound attenuation spectroscopy. The attenuation spectra that are acquired\nin the frequency range $10-100$ MHz are used to determine the particle size\ndistributions (PSDs) for different concentrations and ages of the clay\nsuspensions. Our analysis, using equivalent spherical diameter (ESD) for\ncircular discs under Stokes drag in samples of concentrations greater than\n1.5\\% w/v, shows that a substantial fraction of the aggregates in suspension\nare actually tactoids that are composed of more than one platelet. This is in\ncontrast to the general belief that clay disperses into individual platelets in\nthe concentration range where their suspensions exhibit glassy behavior. We\nconclude that the incomplete fragmentation of the clay tactoids arises from the\nrapid enhancement of the inter-tactoid Coulombic repulsion."
    },
    {
        "anchor": "Cut-off nonlinearities in the low-temperature vibrations of glasses and\n  crystals: We present a computer simulation study of glassy and crystalline states using\nthe standard Lennard-Jones interaction potential that is truncated at a finite\ncut-off distance, as is typical of many computer simulations. We demonstrate\nthat the discontinuity at the cut-off distance in the first derivative of the\npotential (corresponding to the interparticle force) leads to the appearance of\ncut-off nonlinearities. These cut-off nonlinearities persist into the\nvery-low-temperature regime thereby affecting low-temperature thermal\nvibrations, which leads to a breakdown of the harmonic approximation for many\neigen modes, particularly for low-frequency vibrational modes. Furthermore,\nwhile expansion nonlinearities which are due to higher order terms in the\nTaylor expansion of the interaction potential are usually ignored at low\ntemperatures and show up as the temperature increases, cut-off nonlinearities\ncan become most significant at the lowest temperatures. Anharmonic effects\nreadily show up in the elastic moduli which not only depend on the eigen\nfrequencies, but are crucially sensitive to the eigen vectors of the normal\nmodes. Whereas, those observables that rely mainly on static structural\ninformation or just the eigen frequencies, such as the vibrational density of\nstates, total potential energy, and specific heat, show negligible dependence\non the presence of the cut-off. Similar aspects of nonlinear behavior have\nrecently been reported in model granular materials, where the constituent\nparticles interact through finite-range, purely-repulsive potentials. These\nnonlinearities have been ascribed to the nature of the sudden cut-off at\ncontact in the force-law, thus we demonstrate that cut-off nonlinearities\nemerge as a general feature of ordered and disordered solid state systems\ninteracting through truncated potentials.",
        "positive": "Understanding shape entropy through local dense packing: Entropy drives the phase behavior of colloids ranging from dense suspensions\nof hard spheres or rods to dilute suspensions of hard spheres and depletants.\nEntropic ordering of anisotropic shapes into complex crystals, liquid crystals,\nand even quasicrystals has been demonstrated recently in computer simulations\nand experiments. The ordering of shapes appears to arise from the emergence of\ndirectional entropic forces (DEFs) that align neighboring particles, but these\nforces have been neither rigorously defined nor quantified in generic systems.\nHere, we show quantitatively that shape drives the phase behavior of systems of\nanisotropic particles upon crowding through DEFs. We define DEFs in generic\nsystems, and compute them for several hard particle systems. We show that they\nare on the order of a few kT at the onset of ordering, placing DEFs on par with\ntraditional depletion, van der Waals, and other intrinsic interactions. In\nexperimental systems with these other interactions, we provide direct\nquantitative evidence that entropic effects of shape also contribute to\nself-assembly. We use DEFs to draw a distinction between self-assembly and\npacking behavior. We show that the mechanism that generates directional\nentropic forces is the maximization of entropy by optimizing local particle\npacking. We show that this mechanism occurs in a wide class of systems, and we\ntreat, in a unified way, the entropy-driven phase behavior of arbitrary shapes\nincorporating the well-known works of Kirkwood, Onsager, and Asakura and\nOosawa."
    },
    {
        "anchor": "Stress accumulation around ice in a temperature gradient: When materials freeze, they often undergo damage due to ice growth. Although\nthis damage is commonly ascribed to the volumetric expansion of water upon\nfreezing, it is usually driven by suction of water towards growing ice\ncrystals. The freezing of this additional water can cause a large build up of\nstress. Here, we study this process by producing a stable ice/water interface\nin a controlled temperature gradient, and measuring the deformation of the\nconfining boundary. Analysis of the deformation field reveals stresses applied\nto the boundary with $\\mathcal{O}(\\mu\\mathrm{m})$ resolution. Globally,\nstresses increase steadily over time as liquid water is transported to more\ndeeply undercooled regions. Locally, stresses increase until ice growth is\nstalled by the confining stresses. In accordance with the Clapeyron equation,\nthe local limiting stress is proportional to the local undercooling. These\nresults are closely connected to the crystallization pressure for growing\ncrystals and condensation pressure during liquid-liquid phase separation.",
        "positive": "A deformable elastic membrane embedded in a lattice Boltzmann fluid: A method is described for embedding a deformable, elastic, membrane within a\nlattice Boltzmann fluid. The membrane is represented by a set of massless\npoints which advect with the fluid and which impose forces on the fluid which\nare derived from a free energy functional with a value which is dependent upon\nthe geometric properties of the membrane. The method is validated in two\ndimensions with a free energy functional which imposes the constraint of\nconstant membrane length, constant enclosed area, a bending rigidity and a\npreferred curvature. The method is shown to recover the expected equilibrium\nshape in the absence of flow and deformation in the presence of an applied\nshear flow. The method may have applications in a number of mesoscopic\nsimulations, including discrete models of blood cells."
    },
    {
        "anchor": "Reduced-order approach for soft material inertial cavitation rheometry: An understanding of inertial cavitation is crucial for biological and\nengineering applications such as non-invasive tissue surgeries and the\nmitigation of potential blast injuries. However, predictive modeling of\ninertial cavitation in biological tissues is hindered by the difficulties of\ncharacterizing fluids and soft materials at high strain rates, and the\ncomputational cost of calibrating biologically-relevant viscoelastic models. By\nincorporating a reduced-order model of inertial cavitation in the inertial\nmicrocavitation rheometry (IMR) experimental technique, we present an efficient\nprocedure to inversely characterize viscoelastic material subjected to inertial\ncavitation. Instead of brute-force iteration of constitutive model parameters,\nthe present approach directly estimates the elastic and viscous moduli\naccording to the size-dependent scaling of bubble dynamics. Through\nreproduction of numerical-simulated inertial cavitation kinematics and\nexperimental characterization of benchmark materials, we demonstrate that the\nproposed framework can determine the complex rate-dependent properties of soft\nsolid with a small number of numerical simulations. The availability of this\nprocedure will broaden the applicability of IMR for localized characterization\nof fluids and soft biological materials at high strain rates.",
        "positive": "Active Jamming at Criticality: Jamming is ubiquitous in disordered systems, but the critical behavior of\njammed solids subjected to active forces or thermal fluctuations remains\nelusive. In particular, while passive athermal jamming remains mean-field-like\nin two and three dimensions, diverse active matter systems exhibit anomalous\nscaling behavior in all physical dimensions. It is therefore natural to ask\nwhether activity leads to anomalous scaling in jammed systems. Here, we use\nnumerical and analytical methods to study systems of active, soft, frictionless\nspheres in two dimensions, and elucidate the universal scaling behavior that\nrelates the excess coordination, active forces or temperature, and pressure\nclose to the athermal jammed point. We show that active forces and thermal\neffects around the critical jammed state can again be captured by a mean-field\npicture, thus highlighting the distinct and crucial role of amorphous structure\nin active matter systems."
    },
    {
        "anchor": "Analysis of a Lennard-Jones fcc structure melting to the corresponding\n  frozen liquid: differences between the bulk and the surface: We computed a Lennard Jones frozen liquid with a free surface using classical\nmolecular dynamics. The structure factor curves on the free surface of this\nsample was calculated for different depths knowing that we have periodic\nboundary conditions on the other parts of the sample. The resulting structure\nfactor curves show an horizontal shift of their first peak depending on how\ndeep in the sample the curves are computed. We analyze our resulting curves in\nthe light of spatial correlation functions during melting and at when the\nliquid is frozen. The conclusion is that near the free surface the sample is\nless dense than in the bulk and that the frozen liquid surface has a spatial\ncorrelation which does not differ very much from that of the bulk. This result\nis intrinsic to the melting of the Lennard Jones liquid and does not depend on\nany other parameter.",
        "positive": "Phase behaviour of coarse-grained fluids: Soft condensed matter structures often challenge us with complex many-body\nphenomena governed by collective modes spanning wide spatial and temporal\ndomains. In order to successfully tackle such problems mesoscopic\ncoarse-grained (CG) statistical models are being developed, providing a\ndramatic reduction in computational complexity. CG models provide an\nintermediate step in the complex statistical framework of linking the\nthermodynamics of condensed phases with the properties of their constituent\natoms and molecules. These allow us to offload part of the problem to the CG\nmodel itself and reformulate the remainder in terms of reduced CG phase space.\nHowever, such exchange of pawns to chess pieces, or ``Hamiltonian\nrenormalization'', is a radical step and the thermodynamics of the primary\natomic and CG models could be markedly different. Here, we present a\ncomprehensive study of the phase diagram including binodal and interfacial\nproperties of a novel soft CG model, which includes finite-range attraction and\nsupports liquid phases. Although the model is rooted in similar arguments to\nthe Lennard-Jones (LJ) atomic pair potential, its phase behaviour is\nqualitatively different from that of LJ and features several anomalies such as\nan unusually broad liquid range, change in concavity of the liquid coexistence\nbranch with variation of the model parameters, volume contraction on fusion,\ntemperature of maximum density in the liquid phase and negative thermal\nexpansion in the solid phase. These results provide new insight into the\nconnection between simple potential models and complex emergent condensed\nmatter phenomena."
    },
    {
        "anchor": "Depletion induced demixing and crystallization in binary colloids\n  subjected to an external potential barrier: A binary colloidal mixture of unequal sizes, subjected to an external\npotential barrier, has been investigated using canonical ensemble molecular\ndynamics simulations. The attractive depletion interaction between the external\nbarrier and larger species in the binary mixture causes the mixture to phase\nseparate. At higher volume fractions, a pure phase of larger particles forms\nnear the potential barrier, and the local density of this pure phase is high\nenough that a face centered cubic crystalline domain is formed at this region.\nThis crystalline phase diffuses perpendicular to the external potential\nbarrier. The temperature dependence of diffusivity of larger particles is\nnon-Arrhenius and changes from sub-Arrhenius to super-Arrhenius as the volume\nfraction increases. This crossover from sub-Arrhenius to super-Arrhenius\ndiffusion coincides with the crystalline formation near the potential barrier.",
        "positive": "Ridge Network in Crumpled Paper: The network formed by ridges in a straightened sheet of crumpled paper is\nstudied using a laser profilometer. Square sheets of paper were crumpled into\nballs, unfolded and their height profile measured. From these profiles the\nimposed ridges were extracted as networks. Nodes were defined as intersections\nbetween ridges, and links as the various ridges connecting the nodes. Many\nnetwork and spatial properties have been investigated. The tail of the ridge\nlength distribution was found to follow a power-law whereas the shorter ridges\nfollowed a log-normal distribution. The degree distribution was found to have\nan exponentially decaying tail, and the degree correlation was found to be\ndisassortative. The facets created by the ridges and the Voronoi diagram formed\nby the nodes have also been investigated."
    },
    {
        "anchor": "Foaming properties of protein/pectin electrostatic complexes and foam\n  structure at the nanoscale: The foaming properties, foaming capacity and foam stability, of soluble\ncomplexes of pectin and a globular protein, napin, have been investigated with\na \"Foamscan\" apparatus. Complementary, we also used SANS with a recent method\nconsisting in an analogy between the SANS by foams and the neutron reflectivity\nof films to measure in situ film thickness of foams. The effect of ionic\nstrength, of protein concentration and of charge density of the pectin has been\nanalysed. Whereas the foam stability is improved for samples containing soluble\ncomplexes, no effect has been noticed on the foam film thickness, which is\nalmost around 315 {\\AA} whatever the samples. These results let us specify the\nrole of each specie in the mixture: free proteins contribute to the foaming\ncapacity, provided the initial free protein content in the bulk is sufficient\nto allow the foam formation, and soluble complexes slow down the drainage by\ntheir presence in the Plateau borders, which finally results in the\nstabilisation of foams.",
        "positive": "Free-energy functionals of the electrostatic potential for\n  Poisson-Boltzmann theory: In simulating charged systems, it is often useful to treat some ionic\ncomponents of the system at the mean-field level and solve the\nPoisson-Boltzmann (PB) equation to get their respective density profiles. The\nnumerically intensive task of solving the PB equation at each step of the\nsimulation can be bypassed using variational methods that treat the\nelectrostatic potential as a dynamic variable. But such approaches require the\naccess to a true free-energy functional; a functional that not only provides\nthe correct solution of the PB equation upon extremization, it also evaluates\nto the true free energy of the system at its minimum. Moreover, the numerical\nefficiency of such procedures is further enhanced if the free-energy functional\nis local and is expressed in terms of the electrostatic potential. Existing PB\nfunctionals of the electrostatic potential, while possessing the local\nstructure, are not free-energy functionals. We present a variational\nformulation with a local free-energy functional of the potential. In addition,\nwe also construct a nonlocal free-energy functional of the electrostatic\npotential. These functionals are suited for employment in simulation schemes\nbased on the ideas of dynamical optimization."
    },
    {
        "anchor": "Molecular motors stiffen non-affine semiflexible polymer networks: Reconstituted filamentous actin networks with myosin motor proteins form\nactive gels, in which motor proteins generate forces that drive the network far\nfrom equilibrium. This motor activity can also strongly affect the network\nelasticity; experiments have shown a dramatic stiffening in in vitro networks\nwith molecular motors. Here we study the effects of motor generated forces on\nthe mechanics of simulated 2D networks of athermal stiff filaments. We show how\nheterogeneous internal motor stresses can lead to stiffening in networks that\nare governed by filament bending modes. The motors are modeled as force dipoles\nthat cause muscle like contractions. These contractions \"pull out\" the floppy\nbending modes in the system, which induces a cross-over to a stiffer stretching\ndominated regime. Through this mechanism, motors can lead to a nonlinear\nnetwork response, even when the constituent filaments are themselves purely\nlinear. These results have implications for the mechanics of living cells and\nsuggest new design principles for active biomemetic materials with tunable\nmechanical properties.",
        "positive": "Mechanical disorder of sticky-sphere glasses. II. Thermo-mechanical\n  inannealability: Many structural glasses feature static and dynamic mechanical properties that\ncan depend strongly on glass formation history. The degree of universality of\nthis history-dependence, and what it is possibly affected by, are largely\nunexplored. Here we show that the variability of elastic properties of simple\ncomputer glasses under thermal annealing depends strongly on the strength of\nattractive interactions between the glasses' constituent particles -- referred\nto here as glass `stickiness'. We find that in stickier glasses the stiffening\nof the shear modulus with thermal annealing is strongly suppressed, while the\nthermal-annealing-induced softening of the bulk modulus is enhanced. Our key\nfinding is that the characteristic frequency and density per frequency of soft\nquasilocalized modes becomes effectively invariant to annealing in very sticky\nglasses, the latter are therefore deemed `thermo-mechanically inannealable'.\nThe implications of our findings and future research directions are discussed."
    },
    {
        "anchor": "Electrokinetic Lattice Boltzmann solver coupled to Molecular Dynamics:\n  application to polymer translocation: We develop a theoretical and computational approach to deal with systems that\ninvolve a disparate range of spatio-temporal scales, such as those comprised of\ncolloidal particles or polymers moving in a fluidic molecular environment. Our\napproach is based on a multiscale modeling that combines the slow dynamics of\nthe large particles with the fast dynamics of the solvent into a unique\nframework. The former is numerically solved via Molecular Dynamics and the\nlatter via a multi-component Lattice Boltzmann. The two techniques are coupled\ntogether to allow for a seamless exchange of information between the\ndescriptions. Being based on a kinetic multi-component description of the fluid\nspecies, the scheme is flexible in modeling charge flow within complex\ngeometries and ranging from large to vanishing salt concentration. The details\nof the scheme are presented and the method is applied to the problem of\ntranslocation of a charged polymer through a nanopores. In the end, we discuss\nthe advantages and complexities of the approach.",
        "positive": "Quantitative Study of Polymer Dynamics Through Hierarchical Multi-scale\n  Dynamic Simulations: The long time dynamics of polymeric materials has been extensively studied in\nthe past through various experimental techniques and computer simulations.\nWhile computer simulations typically treat generic, simplified models,\nexperiments deal with specific chemistries. In this letter we present a\nhierarchical approach that combines atomistic and coarse-grained simulations to\nquantitatively study polymer dynamics. As an example we predict diffusion\ncoefficients of atactic polystyrene melts of molecular weights relevant to\npolymer processing (up to 50kDa) without any adjustable parameter and compare\nthe results to experiment."
    },
    {
        "anchor": "Active Microrheology of Networks Composed of Semiflexible Polymers. II.\n  Theory and comparison with simulations: Building on the results of our computer simulation (ArXiv cond-mat/0503573)we\ndevelop a theoretical description of the motion of a bead, embedded in a\nnetwork of semiflexible polymers, and responding to an applied force. The\ntheory reveals the existence of an osmotic restoring force, generated by the\npiling up of filaments in front of the moving bead and first deduced through\ncomputer simulations. The theory predicts that the bead displacement scales\nlike x ~ t^alfa with time, with alfa=0.5 in an intermediate- and alfa=1 in a\nlong-time regime. It also predicts that the compliance varies with\nconcentration like c^(-4/3) in agreement with experiment.",
        "positive": "Bose-Einstein condensation of rubidium atoms in a triaxial TOP-trap: We report the results of experiments with Bose-Einstein condensates of\nrubidium atoms in a triaxial TOP-trap, presenting measurements of the\ncondensate fraction and the free expansion of a condensate released from the\ntrap. The experimental apparatus and the methods used to calibrate the magnetic\ntrapping fields are discussed in detail. Furthermore, we compare the\nperformance of our apparatus with other TOP-traps and discuss possible limiting\nfactors for the sizes of condensates achievable in such traps."
    },
    {
        "anchor": "Fluctuations of a long, semiflexible polymer in a narrow channel: We consider an inextensible, semiflexible polymer or worm-like chain, with\npersistence length $P$ and contour length $L$, fluctuating in a cylindrical\nchannel of diameter $D$. In the regime $D\\ll P\\ll L$, corresponding to a long,\ntightly confined polymer, the average length of the channel $<R_\\parallel>$\noccupied by the polymer and the mean square deviation from the average vary as\n$<R_\\parallel>=[1-\\alpha_\\circ(D/P)^{2/3}]L$ and $<\\Delta\nR_\\parallel^{\\thinspace 2}\\thinspace>=\\beta_\\circ(D^2/P)L$, respectively, where\n$\\alpha_\\circ$ and $\\beta_\\circ$ are dimensionless amplitudes. In earlier work\nwe determined $\\alpha_\\circ$ and the analogous amplitude $\\alpha_\\Box$ for a\nchannel with a rectangular cross section from simulations of very long chains.\nIn this paper we estimate $\\beta_\\circ$ and $\\beta_\\Box$ from the simulations.\nThe estimates are compared with exact analytical results for a semiflexible\npolymer confined in the transverse direction by a parabolic potential instead\nof a channel and with a recent experiment. For the parabolic confining\npotential we also obtain a simple analytic result for the distribution of\n$R_\\parallel$ or radial distribution function, which is asymptotically exact\nfor large $L$ and has the skewed shape seen experimentally.",
        "positive": "The surface potential explains ion specific bubble coalescence\n  inhibition: Hypothesis: Some ions can prevent bubbles from coalescing in water. The\nGibbs-Marangoni pressure has been proposed as an explanation of this\nphenomenon. This repulsive pressure occurs during thin film drainage whenever\nsurface enhanced or surface depleted solutes are present. However, bubble\ncoalescence inhibition is known to depend on which particular combination of\nions are present in a peculiar and unexplained way. This dependence may be\nexplained by the electrostatic surface potential created by the distribution of\nions at the interface, which will alters the natural surface propensity of the\nions and hence the Gibbs-Marangoni pressure.\n  Calculations: A generalised form of the Gibbs-Marangoni pressure is derived\nfor a mixture of solutes and a modified Poisson-Boltzmann equation model is\nused to calculate this pressure for five different electrolyte solutions made\nup of four different ions.\n  Findings: Combining ions with differing surface propensities, i.e., one\nenhanced and one depleted, creates a significant electrostatic surface\npotential which dampens the natural surface propensity of these ions, resulting\nin a reduced Gibbs-Marangoni pressure, which allows bubble coalescence. This\nmechanism explains why the ability of electrolytes to inhibit bubble\ncoalescence is correlated with surface tension for pure electrolytes but not\nfor mixed electrolytes."
    },
    {
        "anchor": "Rheology of a Supercooled Polymer Melt: Molecular dynamics simulations are performed for a polymer melt composed of\nshort chains in quiescent and sheared conditions. The stress relaxation\nfunction $G(t)$ exhibits a stretched exponential form in a relatively early\nstage and ultimately follows the Rouse function in quiescent supercooled state.\nTransient stress evolution after application of shear obeys the linear growth\n$\\int_0^t dt'G(t')$ for strain less than 0.1 and then saturates into a\nnon-Newtonian viscosity. In steady states, strong shear-thinning and elongation\nof chains into ellipsoidal shapes are found at extremely small shear. A glassy\ncomponent of the stress is much enhanced in these examples.",
        "positive": "The Role of Bilayer Tilt Difference in Equilibrium Membrane Shapes: Lipid bilayer membranes below their main transition have two tilt order\nparameters, corresponding to the two monolayers. These two tilts may be\nstrongly coupled to membrane shape but only weakly coupled to each other. We\ndiscuss some implications of this observation for rippled and saddle phases,\nbilayer tubules, and bicontinuous phases. Tilt difference introduces a length\nscale into the elastic theory of tilted fluid membranes. It can drive an\ninstability of the flat phase; it also provides a simple mechanism for the\nspontaneous breaking of inversion symmetry seen in some recent experiments."
    },
    {
        "anchor": "Density Functional Simulation of Spontaneous Formation of Vesicle in\n  Block Copolymer Solutions: We carry out numerical simulations of vesicle formation based on the density\nfunctional theory for block copolymer solutions. It is shown by solving the\ntime evolution equations for concentrations that a polymer vesicle is\nspontaneously formed from the homogeneous state. The vesicle formation\nmechanism obtained by our simulation agree with the results of other\nsimulations based on the particle models as well as experiments. By changing\nparameters such as the volume fraction of polymers or the Flory-Huggins\ninteraction parameter between the hydrophobic subchains and solvents, we can\nobtain the spherical micelles, cylindrical micelles or bilayer structures, too.\nWe also show that the morphological transition dynamics of the micellar\nstructures can be reproduced by controlling the Flory-Huggins interaction\nparameter.",
        "positive": "Tuning the Stability of a Model Quasicrystal and its Approximants with a\n  Periodic Substrate: Quasicrystals and their periodic approximants are complex phases, which have\nby now been observed in many metallic alloys, soft matter systems, and particle\nsimulations. In recent experiments of thin-film perovskites on solid\nsubstrates, the type of complex phase was found to change depending on\nthermodynamic conditions and the type of substrate used. Here, we investigate\nthe effect of a substrate on the relative stability of a two-dimensional model\nquasicrystal and its approximants. Our numerical methods are molecular dynamics\nsimulations and free energy calculations that take into account phason flips\nexplicitly. For weak substrates, we observe an incommensurate-commensurate\ntransition, in which a continuous series of QC approximants locks into a\ndiscrete number of approximants. For stronger substrates, an enhancement of the\nstability of the dodecagonal quasicrystal and a variants of square lattices\nwere found. All phenomena can be explained by the interplay of the model system\nwith the substrate. Our results demonstrate that designing novel complex\nperiodic and quasiperiodic structures by choice of suitable substrates is a\npromising strategy."
    },
    {
        "anchor": "Drying of complex suspensions: We investigate the 3D structure and drying dynamics of complex mixtures of\nemulsion droplets and colloidal particles, using confocal microscopy. Air\ninvades and rapidly collapses large emulsion droplets, forcing their contents\ninto the surrounding porous particle pack at a rate proportional to the square\nof the droplet radius. By contrast, small droplets do not collapse, but remain\nintact and are merely deformed. A simple model coupling the Laplace pressure to\nDarcy's law correctly estimates both the threshold radius separating these two\nbehaviors, and the rate of large-droplet evacuation. Finally, we use these\nsystems to make novel hierarchical structures.",
        "positive": "Holographic Measurements of Anisotropic Three-Dimensional Diffusion of\n  Colloidal Clusters: We measure all nonzero elements of the three-dimensional (3D) diffusion\ntensor D for clusters of colloidal spheres to a precision of 1% or better using\ndigital holographic microscopy. We study both dimers and triangular trimers of\nspheres, for which no analytical calculations of the diffusion tensor exist. We\nobserve anisotropic rotational and translational diffusion arising from the\nasymmetries of the clusters. In the case of the three-particle triangular\ncluster, we also detect a small but statistically significant difference in the\nrotational diffusion about the two in-plane axes. We attribute this difference\nto weak breaking of threefold rotational symmetry due to a small amount of\nparticle polydispersity. Our experimental measurements agree well with\nnumerical calculations and show how diffusion constants can be measured under\nconditions relevant to colloidal self-assembly, where theoretical and even\nnumerical prediction is difficult."
    },
    {
        "anchor": "The Fate of Shear-Oscillated Amorphous Solids: The behavior of shear-oscillated amorphous materials is studied using a\ncoarse-grained model. Samples are prepared at different degrees of annealing\nand then subject to athermal and quasistatic oscillatory deformations at\nvarious fixed amplitudes. The steady-state reached after several oscillations\nis fully determined by the initial preparation and the oscillation amplitude,\nas seen from stroboscopic stress and energy measurements. Under small\noscillations, poorly annealed materials display shear-annealing, while\nultra-stabilized materials are insensitive to them. Yet, beyond a critical\noscillation amplitude, both kind of materials display a discontinuous\ntransition to the same mixed state composed by a fluid shear-band embedded in a\nmarginal solid. Quantitative relations between uniform shear and the\nsteady-state reached with this protocol are established. The transient regime\ncharacterizing the growth and the motion of the shear band is also studied.",
        "positive": "Lattice Boltzmann simulations of two linear microswimmers using the\n  immersed boundary method: The performance of a single or the collection of microswimmers strongly\ndepends on the hydrodynamic coupling among their constituents and themselves.\nWe present a numerical study for a single and a pair of microswimmers based on\nlattice Boltzmann method (LBM) simulations. Our numerical algorithm consists of\ntwo separable parts. Lagrange polynomials provide a discretization of the\nmicroswimmers and the lattice Boltzmann method captures the dynamics of the\nsurrounding fluid. The two components couple via an immersed boundary method.\nWe present data for a single swimmer system and our data also show the onset of\ncollective effects and, in particular, an overall velocity increment of\nclusters of swimmers."
    },
    {
        "anchor": "Parallel Emergence of Rigidity and Collective Motion in a Family of\n  Simulated Glass-Forming Polymer Fluids: The emergence of the solid state in glass-forming materials upon cooling is\naccompanied by changes in both thermodynamic and viscoelastic properties and by\na precipitous drop in fluidity. Here, we investigate changes in basic elastic\nproperties upon cooling in a family of simulated polymer fluids, as\ncharacterized by a number of stiffness measures. We show that $\\tau_{\\alpha}$\ncan be expressed quantitatively both in terms of measures of the material\n``stiffness'', $G_p$ and $\\langle u^2 \\rangle$, and the extent $L$ of\ncooperative particle exchange motion in the form of strings, establishing a\ndirect relation between the growth of emergent elasticity and collective\nmotion. Moreover, the macroscopic stiffness parameters, $G_p$, $B$, and $f_{s,\nq^*}$, can all be expressed quantitatively in terms of the molecular scale\nstiffness parameter, $k_{\\mathrm{B}}T / \\langle u^2 \\rangle$ with\n$k_{\\mathrm{B}}$ being Boltzmann's constant, and we discuss the thermodynamic\nscaling of these properties. We also find that $G_p$ is related to the cohesive\nenergy density $\\Pi_{\\mathrm{CED}}$, pointing to the critical importance of\nattractive interactions in the elasticity and dynamics of glass-forming\nliquids. Finally, we discuss fluctuations in the local stiffness parameter as a\nquantitative measure of elastic heterogeneity and their significance for\nunderstanding both the linear and nonlinear elastic properties of glassy\nmaterials.",
        "positive": "Real-time monitoring of complex moduli from micro-rheology: We describe an approach to online analysis of micro-rheology data using a\nmulti-scale time-correlation method. The method is particularly suited to\nprocess high-volume data streams and compress the relevant information in real\ntime. Using this, we can obtain complex moduli of visco-elastic media without\nsuffering from the high-frequency artefacts that are associated with the\ntruncation errors in the most widely used versions of micro-rheology. Moreover,\nthe present approach obviates the need to choose the time interval for data\nacquisition beforehand. We test our approach first on an artificial data set\nand then on experimental data obtained both for an optically trapped colloidal\nprobe in water and a similar probe in poly-ethylene glycol solutions at various\nconcentrations. In all cases, we obtain good agreement with the bulk rheology\ndata in the region of overlap. We compare our method with the conventional\nKramers-Kronig transform approach and find that the two methods agree over most\nof the frequency regime. For the same data set, the present approach is\nsuperior to Kramers-Kronig at high frequencies and can be made to perform at\nleast comparable at low frequencies."
    },
    {
        "anchor": "Following fluctuating signs: anomalous active superdiffusion of swimmers\n  in anisotropic media: Active (i.e., self-propelled or swimming) particles moving through an\nisotropic fluid exhibit conventional diffusive behavior. We report anomalous\ndiffusion of an active particle moving in an anisotropic, nematic background.\nWhilst the translational motion parallel to the nematic director shows\nballistic behavior, the long-time transverse motion is super-diffusive, with an\nanomalous scaling $\\propto t \\ln t$ of the mean squared displacement with time\n$t$. This behavior is predicted by an analytical theory that we present here,\nand is corroborated by numerical simulation of active particle diffusion in a\nsimple lattice model for a nematic liquid crystal. It is universal for any\ncollection of self-propelled elements (e.g., bacteria or active rods) moving in\na nematic background, provided only that the swimmers are sufficiently dilute\nthat their interactions with each other can be neglected, and that they do not\nperform \"hairpin\" turns.",
        "positive": "Drying-induced stresses in poroelastic drops on rigid substrates: We develop a theory for drying-induced stresses in sessile, poroelastic drops\nundergoing evaporation on rigid surfaces. Using a lubrication-like\napproximation, the governing equations of three-dimensional nonlinear\nporoelasticity are reduced to a single thin-film equation for the drop\nthickness. We find that thin drops experience compressive elastic stresses but\nthe total in-plane stresses are tensile. The mechanical response of the drop is\ndictated by the initial profile of the solid skeleton, which controls the\nin-plane deformation, the dominant components of elastic stress, and sets a\nlimit on the depth of delamination that can potentially occur. Our theory\nsuggests that the alignment of desiccation fractures in colloidal drops is\nselected by the shape of the drop at the point of gelation. We propose that the\nemergence of three distinct fracture patterns in dried blood drops is a\nconsequence of a non-monotonic drop profile at gelation. We also show that\ndepletion fronts, which separate wet and dry solid, can invade the drop from\nthe contact line and localise the generation of mechanical stress during\ndrying. Finally, the finite element method is used to explore the stress\nprofiles in drops with large contact angles."
    },
    {
        "anchor": "Decomposing the stock market intraday dynamics: The correlation matrix formalism is used to study temporal aspects of the\nstock market evolution. This formalism allows to decompose the financial\ndynamics into noise as well as into some coherent repeatable intraday\nstructures. The present study is based on the high-frequency Deutsche\nAktienindex (DAX) data over the time period between November 1997 and September\n1999, and makes use of both, the corresponding returns as well as volatility\nvariations. One principal conclusion is that a bulk of the stock market\ndynamics is governed by the uncorrelated noise-like processes. There exists\nhowever a small number of components of coherent short term repeatable\nstructures in fluctuations that may generate some memory effects seen in the\nstandard autocorrelation function analysis. Laws that govern fluctuations\nassociated with those various components are different, which indicates an\nextremely complex character of the financial fluctuations.",
        "positive": "Progressive friction mobilization and enhanced Janssen's screening in\n  confined granular rafts: Confined two-dimensional assemblies of floating particles, known as granular\nrafts, are prone to develop a highly nonlinear response under compression. Here\nwe investigate the transition to the friction-dominated jammed state and map\nthe gradual development of the internal stress profile with flexible pressure\nsensors distributed along the raft surface. Surprisingly, we observe that the\nsurface stress screening builds up much more slowly than previously thought and\nthat the typical screening distance later dramatically decreases. We explain\nthis behavior in terms of progressive friction mobilization, where the full\namplitude of the frictional forces is only reached after a macroscopic local\ndisplacement. At further stages of compression, rafts of large length-to-width\naspect ratio experience much stronger screenings than the full mobilization\nlimit described by the Janssen's model. We solve this paradox using a simple\nmathematical analysis and show that such enhanced screening can be attributed\nto a localized compaction front, essentially shielding the far field from\ncompressive stresses."
    },
    {
        "anchor": "Phase Transitions in Lyotropic Nematic Gels: In this paper, we discuss the equilibrium phases and collapse transitions of\na lyotropic nematic gel immersed in an isotropic solvent. A nematic gel\nconsists of a cross-linked polymer network with rod-like molecules embedded in\nit. Upon decreasing the quality of the solvent, we find that a lyotropic\nnematic gel undergoes a discontinuous volume change accompanied by an\nisotropic-nematic transition. We also present phase diagrams that these systems\nmay exhibit. In particular, we show that coexistence of two isotropic phases,\nof two nematic phases, or of an isotropic and a nematic phase can occur.",
        "positive": "Inelastic impact of a sphere on a massive plane: nonmonotonic\n  velocity-dependence of the restitution coefficient: We have studied the coefficient of restitution, $\\eta$, in normal collisions\nof a non-rotating sphere on a massive plate for a range of material parameters,\nimpact velocity and sphere size. The measured coefficient of restitution does\nnot monotonically vary with velocity. This effect is due to dynamics that occur\nduring the finite duration of impact: the contact time varies as a function of\nvelocity is comparable to the time-scales of the vibrational modes of the\nplate. The measured effect is robust and is expected to be ubiquitous in\nfluidized granular media. We also find that $\\eta$ is a decreasing function of\nparticle size, a dependence that is not captured by existing models of impact."
    },
    {
        "anchor": "Interplay between excitation kinetics and reaction-center dynamics in\n  purple bacteria: Photosynthesis is arguably the fundamental process of Life, since it enables\nenergy from the Sun to enter the food-chain on Earth. It is a remarkable\nnon-equilibrium process in which photons are converted to many-body excitations\nwhich traverse a complex biomolecular membrane, getting captured and fueling\nchemical reactions within a reaction-center in order to produce nutrients. The\nprecise nature of these dynamical processes -- which lie at the interface\nbetween quantum and classical behaviour, and involve both noise and\ncoordination -- are still being explored. Here we focus on a striking recent\nempirical finding concerning an illumination-driven transition in the\nbiomolecular membrane architecture of {\\it Rsp. Photometricum} purple bacteria.\nUsing stochastic realisations to describe a hopping rate model for excitation\ntransfer, we show numerically and analytically that this surprising shift in\npreferred architectures can be traced to the interplay between the excitation\nkinetics and the reaction center dynamics. The net effect is that the bacteria\nprofit from efficient metabolism at low illumination intensities while using\ndissipation to avoid an oversupply of energy at high illumination intensities.",
        "positive": "Architected Lattices with Adaptive Energy Absorption: Energy absorbing materials, like foams used in protective equipment, are able\nto undergo large deformations under low stresses, reducing the incoming stress\nwave below an injury or damage threshold. They are typically effective in\nabsorbing energy through plastic deformation or fragmentation. However,\nexisting solutions are passive, only effective against specific threats and\nthey are usually damaged after use. Here, we overcome these limitations\ndesigning energy absorbing materials that use architected lattices filled with\ngranular particles. We use architected lattices to take advantage of controlled\nbending and buckling of members to enhance energy absorption. We actively\ncontrol the negative pressure level within the lattices, to tune the jamming\nphase transition of the granular particles, inducing controllable energy\nabsorption and recoverable deformations. Our system shows tunable stiffness and\nyield strength by over an order of magnitude, and reduces the transmitted\nimpact stress at different levels by up to 40% compared to the passive lattice.\nThe demonstrated adaptive energy absorbing system sees wide potential\napplications from personal protective equipment, vehicle safety systems to\naerospace structures."
    },
    {
        "anchor": "Liquid State Anomalies for the Stell-Hemmer Core-Softened Potential: We study the Stell-Hemmer potential using both analytic (exact $1d$ and\napproximate $2d$) solutions and numerical $2d$ simulations. We observe in the\nliquid phase an anomalous decrease in specific volume and isothermal\ncompressibility upon heating, and an anomalous increase in the diffusion\ncoefficient with pressure. We relate the anomalies to the existence of two\ndifferent local structures in the liquid phase. Our results are consistent with\nthe possibility of a low temperature/high pressure liquid-liquid phase\ntransition.",
        "positive": "Thermal Shear Waves induced in Mesoscopic Liquids at Low Frequency\n  Mechanical Deformation: We show that a viscous liquid confined between two low thermal conductive\nsurfaces (Al2O3) emit a thermal response upon applying a low frequency (Hz)\nshear excitation. Hot and cold thermal waves are observed in situ at\natmospheric pressure and room temperature, in polypropylene glycol layers of\nvarious thicknesses ranging from 100 microns up to 340 microns, upon applying a\nmechanical oscillatory shear strain. The observed thermal effects, synchronous\nwith the mechanical excitation, are inconsistent with a homogeneous viscous\nflow. It indicates that mesoscopic liquids are able to (partly) convert\nmechanical shear energy in non-equilibrium thermodynamic states. This effect\ncalled thermoelasticity is well known in solid materials. The observation of a\nthermal coupling to the mechanical shear deformation reinforces the assumption\nof elastically correlated liquid molecules. The amplitude of the thermoelastic\nwaves increases linearly by increasing the shear strain amplitude up to a\ntransition to a non-linear thermal behavior, similar in strain behavior to an\nelastic to plastic regime. The thermo-elastic effects are not detectable via\nstress measurements and thus appear as a complementary liquid dynamic\ncharacterization."
    },
    {
        "anchor": "Spontaneous Domain Formation in Spherically-Confined Elastic Filaments: Although the free energy of a genome packing into a virus is dominated by\nDNA-DNA interactions, ordering of the DNA inside the capsid is\nelasticity-driven, suggesting general solutions with DNA organized into\nspool-like domains. Using analytical calculations and computer simulations of a\nlong elastic filament confined to a spherical container, we show that the\nground state is not a single spool as assumed hitherto, but an ordering mosaic\nof multiple homogeneously-ordered domains. At low densities, we observe\nconcentric spools, while at higher densities, other morphologies emerge, which\nresemble topological links. We discuss our results in the context of metallic\nwires, viral DNA, and flexible polymers.",
        "positive": "Synthesis and self-assembly of aminyl and alkynyl substituted\n  sophorolipids: Sophorolipids are one of the most important microbial biosurfactants, because\nof their large-scale production and applications developed so far in the fields\nof detergency, microbiology, cosmetics or environmental science. However, the\nstructural variety of native sophorolipids is limited/restricted, a limiting\nfact for the development of new properties and their potential applications. In\ntheir open acidic form, C18:1 sophorolipids (SL) are classically composed of a\nsophorose headgroup and a carboxylic acid (COOH) end-group. The carboxyl group\ngives them unique pH-responsive properties, but they are a poorly-reactive\ngroup and their charge can only be negative. To develop a new generation of\npH-responsive, positively-charged, SL and to improve their reactivity for\nfurther functionalization, we develop here SLs with an amine (-NH2) or terminal\nalkyne (-C$\\not\\equiv$CH) end-group analogues. The amine group generates\npositively-charged SL and is more reactive than carboxylic acids, e.g. towards\naldehydes; the alkyne group provides access to copper-based click chemistry. In\nthis work, we synthesize (C18:1) and (C18:0) --NH2 and (C18:1) -C$\\not\\equiv$CH\nsophorolipid derivatives and we study their self-assembly properties in\nresponse to pH and/or temperature changes by means of static and dynamic light\nscattering, small angle (X-ray, neutron) scattering and cryogenic electron\nmicroscopy. Monounsaturated aminyl SL-C18:1-NH2 sophorolipids form a micellar\nphase in their neutral form at high pH and a mixed micellar-bilayer phase in\ntheir positively-charged form at low pH. Saturated aminyl SL-C18:0-NH2\nsophorolipids form a micellar phase in their charged form at low pH and a\ntwisted ribbon phase in their neutral form at high pH and monounsaturated\nalkynyl SL-C18:1-C$\\not\\equiv$CH sophorolipids form a main micellar phase at T>\n51.8{\\textdegree}C and a twisted ribbon phase at T< 51.8 {\\textdegree}C."
    },
    {
        "anchor": "Superfast collective motion of magnetic particles: It is well-known that magnetic forces can induce a formation of densely\npacked strings of magnetic particles or even sheafs of several strings\n(spindles). Here we show that in a sufficiently strong magnetic field, more\ncomplex aggregates of particles, translating with a much faster speed than\nwould be for a single particle or even a spindle, can be assembled at the\nwater-air interface. Such a superfast flotilla is composed of many distant\nstrings or spindles, playing a role of its vessels, and moves, practically, as\na whole. We provide theoretical results to interpret the effect of a collective\nmotion of such magnetic vessels. Our theory shows that, in contrast to an\nisolated chain or spindle, which velocity grows logarithmically with the number\nof magnetic particles, the speed of the interface flotilla becomes much higher,\nbeing proportional to the square root of their number. These results may guide\nthe design of magnetic systems for extremely fast controlled delivery.",
        "positive": "Dynamic Gradients, Mobile Layers, Tg Shifts, Role of Vitrification\n  Criterion and Inhomogeneous Decoupling in Free-Standing Polymer Films: The force-level Elastically Collective Nonlinear Langevin Equation theory of\nactivated relaxation in glass-forming free-standing thin films is re-visited to\nimprove its treatment of collective elasticity effects. The naive cut off of\nthe isotropic bulk displacement field approximation is improved to explicitly\ninclude spatial anisotropy with a modified boundary condition consistent with a\nstep function liquid-vapor interface. The consequences of this improvement on\ndynamical predictions are quantitative but of significant magnitude and in the\ndirection of further speeding up dynamics and further suppressing Tg. The\ntheory is applied to thin films and also thick films to address new questions\nfor three different polymers of different dynamic fragility. Variation of the\nvitrification time scale criterion over many orders of magnitude is found to\nhave a minor effect on changes of the film-averaged Tg relative to its bulk\nvalue. The mobile layer length scale grows strongly with cooling and correlates\nin a nearly linear manner with the effective barrier deduced from the\ncorresponding bulk isotropic liquid alpha relaxation time. The theory predicts\na new type of spatially inhomogeneous \"dynamic decoupling\" corresponding to an\neffective factorization of the total barrier into its bulk\ntemperature-dependent value multiplied by a function that only depends on\nlocation in the film. The effective decoupling exponent grows as the vapor\nsurface is approached. Larger reductions of the absolute value of Tg shifts in\nthin polymer films are predicted for longer time vitrification criteria and\nmore fragile polymers. Quantitative no-fit-parameter comparisons with\nexperiment and simulation for film-thickness-dependent Tg shifts of PS and PC\nare in reasonable accord with the theory, including a nearly 100 K suppression\nof Tg in 4 nm PC films. Predictions are made for polyisobutylene thin films."
    },
    {
        "anchor": "Tailoring the Phonon Band Structure in Binary Colloidal Mixtures: We analyze the phonon spectra of periodic structures formed by\ntwo-dimensional mixtures of dipolar colloidal particles. These mixtures display\nan enormous variety of complex ordered configurations [J. Fornleitner {\\it et\nal.}, Soft Matter {\\bf 4}, 480 (2008)], allowing for the systematic\ninvestigation of the ensuing phonon spectra and the control of phononic gaps.\nWe show how the shape of the phonon bands and the number and width of the\nphonon gaps can be controlled by changing the susceptibility ratio, the\nconcentration and the mass ratio between the two components.",
        "positive": "Monte Carlo simulation of a two-field effective Hamiltonian of complete\n  wetting: Recent work on the complete wetting transition for three dimensional systems\nwith short-ranged forces has emphasized the role played by the coupling of\norder-parameter fluctuations near the wall and depinning interface. It has been\nproposed that an effective two-field Hamiltonian, which predicts a\nrenormalisation of the wetting parameter, could explain the controversy between\nRG analysis of the capillary-wave model and Monte Carlo simulations on the\nIsing model. In this letter results of extensive Monte Carlo simulations of the\ntwo-field model are presented. The results are in agreement with prediction of\na renormalized wetting parameter $\\omega $."
    },
    {
        "anchor": "Ionic fluctuations in finite volumes: fractional noise and\n  hyperuniformity: Observing finite regions of a bigger system is a common experience, from\nmicroscopy to molecular simulations. In the latter especially, there is ongoing\ninterest in predicting thermodynamic properties from tracking fluctuations in\nfinite observation volumes. However, kinetic properties have received less\nattention, especially not in ionic solutions, where electrostatic interactions\nplay a decisive role. Here, we probe ionic fluctuations in finite volumes with\nBrownian dynamics and build an analytical framework that reproduces our\nsimulation results and is broadly applicable to other systems with pairwise\ninteractions. Particle number and charge correlations exhibit a rich\nphenomenology with time, characterized by a diversity of timescales. The noise\nspectrum of both quantities decays as $1/f^{3/2}$, where $f$ is the frequency.\nThis signature of fractional noise shows the universality of $1/f^{3/2}$\nscalings when observing diffusing particles in finite domains. The hyperuniform\nbehaviour of charge fluctuations, namely that correlations scale with the area\nof the observation volume, is preserved in time. Correlations even become\nproportional to the box perimeter at sufficiently long times. Our results pave\nthe way to understand fluctuations in more complex systems, from nanopores to\nsingle-particle electrochemistry.",
        "positive": "Rate-dependent drag instability in granular materials: We investigate the conditions leading to large drag force fluctuations in\ngranular materials. The study is based on a set of experimental drag tests,\nwhich involve pulling a plate vertically through a cohesionless granular\nmaterial. In agreement with previous observations, drag force exhibits\nsignificant and sudden drops -up to 60%- when the plate is pulled out at low\nvelocities. We further find that this instability vanishes at higher pullout\nvelocities and near the surface. We empirically characterise the frequency and\namplitude of these fluctuations and find that these properties are not\nconsistent with a classical stick-slip dynamics. We therefore propose an\nalternative physical mechanism that can explain these force fluctuations."
    },
    {
        "anchor": "Numerical study of domain coarsening in anisotropic stripe patterns: We study the coarsening of two-dimensional smectic polycrystals characterized\nby grains of oblique stripes with only two possible orientations. For this\npurpose, an anisotropic Swift-Hohenberg equation is solved. For quenches close\nenough to the onset of stripe formation, the average domain size increases with\ntime as $t^{1/2}$. Further from onset, anisotropic pinning forces similar to\nPeierls stresses in solid crystals slow down defects, and growth becomes\nanisotropic. In a wide range of quench depths, dislocation arrays remain mobile\nand dislocation density roughly decays as $t^{-1/3}$, while chevron boundaries\nare totally pinned. We discuss some agreements and disagreements found with\nrecent experimental results on the coarsening of anisotropic electroconvection\npatterns.",
        "positive": "Geometry of Frictionless and Frictional Sphere Packings: We study static packings of frictionless and frictional spheres in three\ndimensions, obtained via molecular dynamics simulations, in which we vary\nparticle hardness, friction coefficient, and coefficient of restitution.\nAlthough frictionless packings of hard-spheres are always isostatic (with six\ncontacts) regardless of construction history and restitution coefficient,\nfrictional packings achieve a multitude of hyperstatic packings that depend on\nsystem parameters and construction history. Instead of immediately dropping to\nfour, the coordination number reduces smoothly from $z=6$ as the friction\ncoefficient $\\mu$ between two particles is increased."
    },
    {
        "anchor": "Critical Scaling of Shear Viscosity at the Jamming Transition: We carry out numerical simulations to study transport behavior about the\njamming transition of a model granular material in two dimensions at zero\ntemperature. Shear viscosity \\eta is computed as a function of particle volume\ndensity \\rho and applied shear stress \\sigma, for diffusively moving particles\nwith a soft core interaction. We find an excellent scaling collapse of our data\nas a function of the scaling variable \\sigma/|\\rho_c-\\rho|^\\Delta, where \\rho_c\nis the critical density at \\sigma=0 (\"point J\"), and \\Delta is the crossover\nscaling critical exponent. Our results show that jamming is a true critical\nphenomenon, extending to driven steady states along the non-equilibrium \\sigma\naxis of the \\rho-\\sigma phase diagram.",
        "positive": "Hard sphere crystal nucleation rates: Reconciliation of simulation and\n  experiment: Over the past two decades, a large number of studies addressed the topic of\ncrystal nucleation in suspensions of hard spheres. The shared result of all\nthese efforts is that, at low super-saturations, experimentally observed\nnucleation rates and numerically computed ones differ by more than ten orders\nof magnitude. We present precise simulation results of crystal nucleation rate\ndensities in the meta-stable hard sphere liquid. To compare these rate\ndensities to experimentally measured ones, we propose an interpretation of the\nexperimental data as a combination of nucleation and crystal growth processes\n(rather than purely the nucleation process). This interpretation may resolve\nthe long standing dispute about the differing rates."
    },
    {
        "anchor": "Breakdown of continuum elasticity in amorphous solids: We show numerically that the response of simple amorphous solids (elastic\nnetworks and particle packings) to a local force dipole is characterized by a\nlengthscale $\\ell_c$ that diverges as unjamming is approached as $\\ell_c \\sim\n(z - 2d)^{-1/2}$, where $z \\ge 2d$ is the mean coordination, and $d$ is the\nspatial dimension, at odds with previous numerical claims. We also show how the\nmagnitude of the lengthscale $\\ell_c$ is amplified by the presence of internal\nstresses in the disordered solid. Our data suggests a divergence of $\\ell_c\\sim\n(p_c-p)^{-1/4}$ with proximity to a critical internal stress $p_c$ at which\nsoft elastic modes become unstable.",
        "positive": "Self-assembly and percolation in magnetic colloids: We study the self-assembly of branching-chain networks and crystals in a\nbinary colloidal system with tunable interactions. The particle positions are\nextracted from microscope images and order parameters are extracted by image\nprocessing and statistical analysis. With these, we construct phase diagrams\nwith respect to particle density, ratio and interaction. In order to draw a\nmore complete picture, we complement the experiments with computer simulations.\nWe establish a region in the phase diagram, where bead ratios and interactions\nare symmetric, promoting percolated structures."
    },
    {
        "anchor": "Fluctuations of cell geometry and their non-equilibrium thermodynamics\n  in living epithelial tissue: We measure different contributions to entropy production in a living\nfunctional epithelial tissue. We do this by extracting the functional dynamics\nof development while at the same time quantifying fluctuations. Using the\ntranslucent Drosophila melanogaster pupal epithelium as an ideal tissue for\nhigh resolution live imaging [1], we measure the entropy associated with the\nstochastic geometry of cells in the epithelium. This is done using a detailed\nanalysis of the dynamics of the shape and orientation of individual cells which\nenables separation of local and global aspects of the tissue behaviour. We find\nintriguingly that we can observe irreversible dynamics in the cell geometries\nbut without a change in the entropy associated with those degrees of freedom,\nshowing that there is a flow of energy into those degrees of freedom. Hence the\nliving system is controlling how the entropy is being produced and partitioned\ninto its different parts.",
        "positive": "Swimming statistics of cargo-loaded single bacteria: Burgeoning interest in the area of bacteria-powered micro robotic systems\nprompted us to study the dynamics of cargo transport by single bacteria. In\nthis paper, we have studied the swimming behaviour of oil-droplets attached as\na cargo to the cell bodies of single bacteria. The oil-droplet loaded bacteria\nexhibit super-diffusive motion which is characterized by high degree of\ndirectional persistence. Interestingly, bacteria could navigate even when\nloaded with oil-droplets as large as 8 microns with an effective increase in\nrotational drag by more than 2 orders when compared to free bacteria. Further,\nthe directional persistence of oil-droplet loaded bacteria was independent of\nthe cargo size."
    },
    {
        "anchor": "Ions and dipoles in electric field: Nonlinear polarization and\n  field-dependent chemical reaction: We investigate electric-field effects in dilute electrolytes with nonlinear\npolarization. As a first example of such systems, we add a dipolar component\nwith a relatively large dipole moment $\\mu_0$ to an aqueous electrolyte. As a\nsecond example, the solvent itself exhibits nonlinear polarization near charged\nobjects. For such systems, we present a Ginzburg-Landau free energy and\nintroduce field-dependent chemical potentials, entropy density, and stress\ntensor, which satisfy general thermodynamic relations. In the first example,\nthe dipoles accumulate in high-field regions, as predicted by Abrashikin {\\it\net al}.$[$Phys.Rev.Lett. {\\bf 99}, 077801 (2007)$]$. Finally, we consider the\ncase, where Bjerrum ion pairs form a dipolar component with nonlinear\npolarization. The Bjerrum dipoles accumulate in high-field regions, while\nfield-induced dissociation was predicted by Onsager $[$J. Chem. Phys.{\\bf 2},\n599 (1934)$]$. We present an expression for the field-dependent association\nconstant $K(E)$, which depends on the field strength nonmonotonically.",
        "positive": "Bridging Heterogeneity Dictates the Microstructure and Yielding Response\n  of Polymer-Linked Emulsions: Soft materials possessing tunable rheological properties are desirable in\napplications ranging from 3D printing to biological scaffolds. Here, we use a\ntelechelic, triblock copolymer polystyrene-b-poly(ethylene oxide)-b-polystyrene\n(SEOS) to form elastic networks of polymer-linked droplets in\ncyclohexane-in-water emulsions. The SEOS endblocks partition into the dispersed\ncyclohexane droplets while the midblocks remain in the aqueous continuous\nphase, resulting in each chain taking on either a looping or bridging\nconformation. We examine the yield transition of these polymer-linked emulsions\nthrough large amplitude oscillatory shear (LAOS) and probe the emulsion\nstructure through confocal microscopy, concluding that polymers that more\nreadily form bridges generate a strongly percolated network, whereas those that\nare less prone to form bridges tend to produce networks composed of\nweakly-linked clusters of droplets. When yielded, the emulsions consisting of\nlinked clusters break apart into individual clusters that can rearrange upon\nthe application of further shear. By contrast, when the systems containing a\nmore homogeneous bridging density are yielded, the system remains percolated\nbut with a reduced elasticity and bridging density. The demonstrated ability of\ntelechelic triblock copolymers to tune not only the linear viscoelasticity of\ncomplex fluids but also their nonlinear yield transition enables the use of\nthese polymers as versatile and robust rheological modifiers. We expect our\nfindings to therefore aid the design of the next generation of complex fluids\nand soft materials."
    },
    {
        "anchor": "Mechanics of large folds in thin interfacial films: A thin film at a liquid interface responds to uniaxial confinement by\nwrinkling and then by folding; its shape and energy have been computed exactly\nbefore self contact. Here, we address the mechanics of large folds, i.e. folds\nthat absorb a length much larger than the wrinkle wavelength. With scaling\narguments and numerical simulations, we show that the antisymmetric fold is\nenergetically favorable and can absorb any excess length at zero pressure.\nThen, motivated by puzzles arising in the comparison of this simple model to\nexperiments on lipid monolayers and capillary rafts, we discuss how to\nincorporate film weight, self-adhesion and energy dissipation.",
        "positive": "Beyond the Tradeoff: Dynamic Selectivity in Ionic Transport and Current\n  Selectivity: Traditionally, ion-selectivity in nanopores and nanoporous membranes is\nunderstood to be a consequence of Debye overlap, in which the Debye screening\nlength is comparable to the nanopore radius somewhere along the length of the\nnanopore(s). This criterion sets a significant limitation on the size of\nion-selective nanopores, as the Debye length is on the order of 1 - 10 nm for\ntypical ionic concentrations. However, the analytical results we present here\ndemonstrate that surface conductance generates a dynamical selectivity in ion\ntransport, and this selectivity is controlled by so-called Dukhin, rather than\nDebye, overlap. The Dukhin length, defined as the ratio of surface to bulk\nconductance, reaches values of hundreds of nanometers for typical surface\ncharge densities and ionic concentrations, suggesting the possibility of\ndesigning large-nanopore (10 - 100 nm), high-conductance membranes exhibiting\nsignificant ion-selectivity. Such membranes would have potentially dramatic\nimplications for the efficiency of osmotic energy conversion and separation\ntechniques. Furthermore, we demonstrate that this mechanism of dynamic\nselectivity leads ultimately to the rectification of ionic current,\nrationalizing previous studies showing that Debye overlap is not a necessary\ncondition for the occurrence of rectifying behavior in nanopores."
    },
    {
        "anchor": "Interface structures in ionic liquid crystals: Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which\nadditionally carry charges. This combination gives rise to a complex interplay\nof the underlying (anisotropic) contributions to the pair interactions. It\npromises interesting and distinctive structural and orientational properties to\narise in systems of ILCs, combining properties of liquid crystals and ionic\nliquids. While previous theoretical studies have focused on the phase behavior\nof ILCs and the structure of the respective bulk phases, in the present study\nwe provide new results, obtained within density functional theory, concerning\n(planar) free interfaces between an isotropic liquid $L$ and two types of\nsmectic-A phases ($S_A$ or $S_{AW}$). We discuss the structural and\norientational properties of these interfaces in terms of the packing fraction\nprofile $\\eta(\\vec{r})$ and the orientational order parameter profile\n$S_2(\\vec{r})$ concerning the tilt angle $\\alpha$ between the (bulk) smectic\nlayer normal and the interface normal. The asymptotic decay of $\\eta(\\vec{r})$\nand of $S_2(\\vec{r})$ towards their values in the isotropic bulk is discussed,\ntoo.",
        "positive": "The effect of a reversible shear transformation on plastic deformation\n  of an amorphous solid: Molecular dynamics simulations are performed to investigate the plastic\nresponse of a model glass to a local shear transformation in a quiescent\nsystem. The deformation of the material is induced by a spherical inclusion\nthat is gradually strained into an ellipsoid of the same volume and then\nreverted back into the sphere. We show that the number of cage-breaking events\nincreases with increasing strain amplitude of the shear transformation. The\nresults of numerical simulations indicate that the density of cage jumps is\nlarger in the cases of weak damping or slow shear transformation. Remarkably,\nwe also found that, for a given strain amplitude, the peak value of the density\nprofiles is a function of the ratio of the damping coefficient and the time\nscale of the shear transformation."
    },
    {
        "anchor": "Oscillatory driven colloidal binary mixtures: axial segregation versus\n  laning: Using Brownian dynamics computer simulations we show that binary mixtures of\ncolloids driven in opposite directions by an oscillating external field exhibit\naxial segregation in sheets perpendicular to the drive direction. The\nsegregation effect is stable only in a finite window of oscillation frequencies\nand driving strengths and is taken over by lane formation in direction of the\ndriving field if the driving force is increased. In the crossover regime, bands\ntilted relative to the drive direction are observed. Possible experiments to\nverify the axial segregation are discussed.",
        "positive": "Hard sphere crystallization gets rarer with increasing dimension: We recently found that crystallization of monodisperse hard spheres from the\nbulk fluid faces a much higher free energy barrier in four than in three\ndimensions at equivalent supersaturation, due to the increased geometrical\nfrustration between the simplex-based fluid order and the crystal [J.A. van\nMeel, D. Frenkel, and P. Charbonneau, Phys. Rev. E 79, 030201(R) (2009)]. Here,\nwe analyze the microscopic contributions to the fluid-crystal interfacial free\nenergy to understand how the barrier to crystallization changes with dimension.\nWe find the barrier to grow with dimension and we identify the role of\npolydispersity in preventing crystal formation. The increased fluid stability\nallows us to study the jamming behavior in four, five, and six dimensions and\ncompare our observations with two recent theories [C. Song, P. Wang, and H. A.\nMakse, Nature 453, 629 (2008); G. Parisi and F. Zamponi, Rev. Mod. Phys, in\npress (2009)]."
    },
    {
        "anchor": "The low noise phase of a 2d active nematic: We consider a collection of self-driven apolar particles on a substrate that\norganize into an active nematic phase at sufficiently high density or low\nnoise. Using the dynamical renormalization group, we systematically study the\n2d fluctuating ordered phase in a coarse-grained hydrodynamic description\ninvolving both the nematic director and the conserved density field. In the\npresence of noise, we show that the system always displays only quasi-long\nranged orientational order beyond a crossover scale. A careful analysis of the\nnonlinearities permitted by symmetry reveals that activity is dangerously\nirrelevant over the linearized description, allowing giant number fluctuations\nto persist though now with strong finite-size effects and a non-universal\nscaling exponent. Nonlinear effects from the active currents lead to power law\ncorrelations in the density field thereby preventing macroscopic phase\nseparation in the thermodynamic limit.",
        "positive": "Thermodynamic perturbation theory for associating fluids confined in a\n  1- dimensional pore: In this paper a new theory is developed for the self - assembly of\nassociating molecules confined to a single spatial dimension, but allowed to\nexplore all orientation angles. The interplay of the anisotropy of the pair\npotential and the low dimensional space, results in orientationally ordered\nassociated clusters. This local order enhances association due to a decrease in\norientational entropy. Unlike bulk 3D fluids which are orientationally\nhomogeneous, association in 1D necessitates the self - consistent calculation\nof the orientational distribution function. To test the new theory, Monte Carlo\nsimulations are performed and the theory is found to be accurate. The theory\ndeveloped in this paper may be used as a tool to study hydrogen bonding of\nmolecules in 1D zeolites as well as hydrogen bonding of water in carbon\nnanotubes."
    },
    {
        "anchor": "Law of corresponding states for osmotic swelling of vesicles: As solute molecules permeate into a vesicle due to a concentration difference\nacross its membrane, the vesicle swells through osmosis. The swelling can be\ndivided into two stages: (a) an \"ironing\" stage, where the volume-to-area ratio\nof the vesicle increases without a significant change in its area; (b) a\nstretching stage, where the vesicle grows while remaining essentially\nspherical, until it ruptures. We show that the crossover between these two\nstages can be represented as a broadened continuous phase transition.\nConsequently, the swelling curves for different vesicles and different\npermeating solutes can be rescaled into a single, theoretically predicted,\nuniversal curve. Such a data collapse is demonstrated for giant unilamellar\nPOPC vesicles, osmotically swollen due to the permeation of urea, glycerol, or\nethylene glycol. We thereby gain a sensitive measurement of the solutes'\nmembrane permeability coefficients, finding a concentration-independent\ncoefficient for urea, while those of glycerol and ethylene glycol are found to\nincrease with solute concentration. In addition, we use the width of the\ntransition, as extracted from the data collapse, to infer the number of\nindependent bending modes that affect the thermodynamics of the vesicle in the\ntransition region.",
        "positive": "Curvature dependence of the electrolytic liquid-liquid interfacial\n  tension: The interfacial tension of a liquid droplet surrounded by another liquid in\nthe presence of microscopic ions is studied as a function of the droplet\nradius. An analytical expression for the interfacial tension is obtained within\na linear Poisson-Boltzmann theory and compared with numerical results from\nnon-linear Poisson-Boltzmann theory. The excess liquid-liquid interfacial\ntension with respect to the pure, salt-free liquid-liquid interfacial tension\nis found to decompose into a curvature-independent part due to short-ranged\ninterfacial effects and a curvature-dependent electrostatic contribution.\nSeveral curvature-dependent regimes of different scaling of the electrostatic\nexcess interfacial tension are identified. Symmetry relations of the\ninterfacial tension upon swapping droplet and bulk liquid are found to hold in\nthe low-curvature limit, which, e.g., lead to a sign change of the excess\nTolman length. For some systems a low-curvature expansion up to second order\nturns out to be applicable if and only if the droplet size exceeds the Debye\nscreening length in the droplet, independent of the Debye length in the bulk."
    },
    {
        "anchor": "Density and structural anomalies in soft-repulsive dimeric fluids: We report Monte Carlo results for the fluid structure of a system of dimeric\nparticles interacting via a core-softened potential. More specifically, dimers\ninteract through a repulsive pair potential of inverse-power form, modified in\nsuch a way that the repulsion strength is softened in a given range of\ndistances. The aim of such a study is to investigate how both the elongation of\nthe dimers and the softness of the potential affect some features of the model.\nOur results show that the dimeric fluid exhibits both density and structural\nanomalies even if the interaction is not characterized by two length scales.\nUpon increasing the aspect ratio of the dimers, such anomalies are\nprogressively hindered, with the structural anomaly surviving even after the\ndisappearance of the density anomaly. These results shed light on the peculiar\nbehaviour of molecular systems of non-spherical shape, showing how geometrical\nand interaction parameters play a fundamental role for the presence of\nanomalies.",
        "positive": "Phantom Chain Simulations for Fracture of End-linking Networks: Despite numerous studies, the relationship between network structure and\nfracture remains unclear. In this study, the fracture properties of end-linking\nnetworks were compared with those of loop-free analogs made from star\nprepolymers by performing phantom chain simulations. The networks were created\nfrom equilibrated sols of stoichiometric mixtures of linear prepolymers and\nf-functional linkers through end-linking reactions using Brownian dynamics\nschemes. The examined networks, with various f values (between 3 and 8) and\nstrand-connection rates ({\\phi}_s), were evaluated in terms of the primary loop\nfraction and the cycle rank {\\xi}. These structural characteristics were\nconsistent with mean-field theories that assume independent reactions. Energy\nminimization and uniaxial stretch were applied to the networks until they broke\nwithout Brownian motion. The fracture characteristics, including strain\n({\\epsilon}_b), stress ({\\sigma}_b), and work for fracture (W_b), were obtained\nfrom stress-strain curves. The end-linking networks exhibited larger\n{\\epsilon}_b and smaller {\\sigma}_b and W_b than those for star networks due to\nprimary loops, at the same set of f and {\\phi}_s. However, {\\epsilon}_b,\n{\\sigma}_b/{\\nu}_br and W_b/{\\nu}_br (with {\\nu}_br being the branch point\ndensity) lie on the same master curves as those for star networks if they are\nplotted against {\\xi}. This result implies that the fracture of end-linking\nnetworks is essentially the same as that for star analogs, and the effects of\nprimary loops are embedded in {\\xi}."
    },
    {
        "anchor": "Ionic current inversion in pressure-driven polymer translocation through\n  nanopores: We predict streaming current inversion with multivalent counterions in\nhydrodynamically driven polymer translocation events from a\ncorrelation-corrected charge transport theory including charge fluctuations\naround mean-field electrostatics. In the presence of multivalent counterions,\nelectrostatic many-body effects result in the reversal of the DNA charge. The\nattraction of anions to the charge-inverted DNA molecule reverses the sign of\nthe ionic current through the pore. Our theory allows for a comprehensive\nunderstanding of the complex features of the resulting streaming currents. The\nunderlying mechanism is an efficient way to detect DNA charge reversal in\npressure-driven translocation experiments with multivalent cations.",
        "positive": "Effects of additives on oil displacement in nanocapillaries: a mesoscale\n  simulation study: We performed mesoscale simulations in order to investigate the effects that\nadditives, such as surfactants and polymers, have in the oil displacement\nprocess by water and brine injection. A Many-Body Dissipative Particle Dynamics\n(MDPD) model was parameterized in order to reproduce physical properties\nobtained either by experiments or Classical Molecular Dynamics (MD). The MDPD\nmodel was then employed to simulate the displacement of n-dodecane by water and\nbrine, with surfactant concentrations ranging from 1 wt. % to 10 wt. % SDS and\npolymer concentration of 0.5 wt. % HPAM. We observed that while the additives\nmay enter the capillary without clogging, specific combinations of surfactant\nconcentrations and injection rates may lead to poor oil displacement. This\nresult can be understood in terms of the balance between water-wall and\n(surface-mediated) water-oil interactions. As a consequence, our results show\nan effective reversal of the wettability character, from water-wet to oil-wet,\nas a function of the interface speed. We conclude by summarizing the\nimplications such results have on the fluid-fluid displacements involving\nadditives."
    },
    {
        "anchor": "Porous silica beads produced by nanofluid emulsion freezing: It is shown that porous spherical particles can be obtained via the freezing\nof silica nanoparticle aqueous suspensions emulsified in a continuous oil\nphase. After two freeze-thaw cycles, nanoparticles turn aggregated into\nflocculated objects with microstructure that depends upon emulsion volume\nfraction and droplet size. For low volume fractions, regular microspheres are\nproduced while for large ones, irregular beads with several tens of micrometer\nradius are formed. Electronic microscopy, mercury porosimetry and nitrogen\nadsorption are used to get insights into these porous particles typical radius,\npore size distribution, surface area and pore network structure. All exhibit\nmesopores that result from inter-nanoparticle spacing after flocculation. An\nunexpected macroporous domain appears which is not observed when drying\nnon-emulsified suspensions. This macroporosity is interpreted as the signature\nof dendrite formation during the undercooled period, right before freezing\noccurs. Beside this additional macroporosity, the protocols presented in this\narticle constitute also promising emulsion-based routes for porous material\nsynthesis with original geometry, chemical composition and porosity.",
        "positive": "Dynamic surface decoupling in a sheared polymer melt: We propose that several mechanisms contribute to friction in a polymer melt\nadsorbed at a structured surface. The first one is the well known\ndisentanglement of bulk polymer chains from the surface layer. However, if the\nsurface is ideal at the atomic scale, the adsorbed parts of polymer chains can\nmove along the equipotential lines of the surface potential. This gives rise to\na strong slippage of the melt. For high shear rates chains partially desorb.\nHowever, the friction force on adsorbed chains increases, resulting in\nquasi-stick boundary conditions. We propose that the adsorbed layers can be\nefficiently used to adjust the friction force between the polymer melt and the\nsurface."
    },
    {
        "anchor": "Directional Transport of Propelled Brownian Particles Confined in a\n  Smooth Corrugated Channel with Colored Noise: The transport phenomenon(directional movement) of self-propelled Brownian\nparticles moving in a smooth corrugated confined channel is investigated. It is\nfound that large $x$ direction noise intensity should reduce particles\ndirectional movement when the angle Gaussian noise intensity is small. The\naverage velocity has a maximum with increasing $x$ direction noise intensity\nwhen angle Gaussian noise intensity is large. $y$ directional noise has\nnegligible effect on $x$ directional movement. Large angle Gaussian noise\nintensity should weaken the directional transport. Interestingly, the movement\ndirection changes more than once with increasing periodic force amplitude.",
        "positive": "New boundary conditions for granular fluids: We present experimental evidence, which contradicts the the standard boundary\nconditions used in continuum theories of non-cohesive granular flows for the\nvelocity normal to a boundary u.n=0, where n points into the fluid. We propose\nand experimentally verify a new boundary condition for u.n, based on the\nobservation that the boundary cannot exert a tension force Fb on the fluid. The\nnew boundary condition is u.n=0 if Fb.n>=0 else n.P.n=0, where P is the\npressure tensor. This is the analog of cavitation in ordinary fluids, but due\nthe lack of attractive forces and dissipation it occurs frequently in granular\nflows."
    },
    {
        "anchor": "Choline chloride as a nano-crowder protects HP-36 from urea-induced\n  denaturation: Insights from Solvent Dynamics and Protein-Solvent interaction: Urea at sufficiently high concentration unfolds the secondary structure of\nproteins leading to denaturation. In contrast, Choline Chloride (ChCl) and\nurea, in 1:2 molar ratio form a deep eutectic mixture, a liquid at room\ntemperature and protect proteins from denaturation. In order to get a\nmicroscopic picture of this phenomenon, we perform extensive all-atom molecular\ndynamics simulations on a model protein HP-36. Based on our calculation of\nKirkwood-Buff integrals, we analyze the relative accumulation of these\nosmolytes around the protein. Additional insights are drawn from the analyses\nof the translational and rotational dynamics of solvent molecules and also from\nthe hydrogen bond auto-correlation functions. In the presence of urea, water\nshows slow subdiffusive dynamics around the protein backbone as a consequence\nof stronger interaction of water molecules with the backbone atoms. Urea also\nshows subdiffusive motion. Addition of choline further slows down the dynamics\nof urea restricting its inclusion around the protein backbone. Adding to this,\ncholine molecules in the first solvation shell of the protein shows the\nstrongest subdiffusive behavior. In other words, ChCl behaves as a nano-crowder\nby excluding urea from the protein backbone and thereby slowing down the\ndynamics of the water layer around the protein. This prevents the protein from\ndenaturation and makes it structurally rigid which in turn is supported by the\nsmaller radius of gyration and root mean square deviation values of HP-36 when\nChCl is present in the system.",
        "positive": "Numerical calculations of the phase diagram of cubic blue phases in\n  cholesteric liquid crystals: We study the static properties of cubic blue phases by numerically minimising\nthe three-dimensional, Landau-de Gennes free energy for a cholesteric liquid\ncrystal close to the isotropic-cholesteric phase transition. Thus we are able\nto refine the powerful but approximate, semi-analytic frameworks that have been\nused previously. We obtain the equilibrium phase diagram and discuss it in\nrelation to previous results. We find that the value of the chirality above\nwhich blue phases appear is shifted by 20% (towards experimentally more\naccessible regions) with respect to previous estimates. We also find that the\nregion of stability of the O5 structure -- which has not been observed\nexperimentally -- shrinks, while that of BP I (O8-) increases thus giving the\ncorrect order of appearance of blue phases at small chirality. We also study\nthe approach to equilibrium starting from the infinite chirality solutions and\nwe find that in some cases the disclination network has to assemble during the\nequilibration. In these situations disclinations are formed via the merging of\nisolated aligned defects."
    },
    {
        "anchor": "Self-propelling colloidal finite state machines: Endowing materials with physical intelligence holds the key for a progress\nleap in robotic systems. In spite of the growing success for macroscopic\ndevices, transferring these concepts to the microscale presents several\nchallenges connected to the lack of suitable fabrication and design techniques,\nand of internal response schemes that connect the materials' properties to the\nfunction of an autonomous unit. Here, we realize self-propelling colloidal\nclusters which behave as simple finite state machines, i.e. systems built to\npossess a finite number of internal states connected by reversible transitions\nand associated to distinct functions. We produce these units via capillary\nassembly combining hard polystyrene colloids with two different types of\nthermo-responsive microgels. The clusters, actuated by spatially uniform AC\nelectric fields, adapt their shape and dielectric properties, and consequently\ntheir propulsion, via reversible temperature-induced transitions controlled by\nlight. The different transition temperatures for the two microgels enable three\ndistinct dynamical states corresponding to three illumination intensity levels.\nThe sequential reconfiguration of the microgels affects the velocity and shape\nof the active trajectories according to a pathway defined by tailoring the\nclusters' geometry during assembly. The demonstration of these simple systems\nindicates an exciting route to build more complex units with broader\nreconfiguration schemes and multiple responses towards the realization of\nautonomous systems with physical intelligence at the colloidal scale.",
        "positive": "The chain sucker: translocation dynamics of a polymer chain into a long\n  narrow channel driven by longitudinal flow: Using analytical techniques and Langevin dynamics simulations, we investigate\nthe dynamics of polymer translocation into a narrow channel of width $R$\nembedded in two dimensions, driven by a force proportional to the number of\nmonomers in the channel. Such a setup mimics typical experimental situations in\nnano/micro-fluidics. During the the translocation process if the monomers in\nthe channel can sufficiently quickly assume steady state motion, we observe the\nscaling $\\tau\\sim N/F$ of the translocation time $\\tau$ with the driving force\n$F$ per bead and the number $N$ of monomers per chain. With smaller channel\nwidth $R$, steady state motion cannot be achieved, effecting a non-universal\ndependence of $\\tau$ on $N$ and $F$. From the simulations we also deduce the\nwaiting time distributions under various conditions for the single segment\npassage through the channel entrance. For different chain lengths but the same\ndriving force, the curves of the waiting time as a function of the\ntranslocation coordinate $s$ feature a maximum located at identical\n$s_{\\mathrm{max}}$, while with increasing the driving force or the channel\nwidth the value of $s_{\\mathrm{max}}$ decreases."
    },
    {
        "anchor": "Irreversible Adsorption from Dilute Polymer Solutions: We study irreversible polymer adsorption from dilute solutions theoretically.\nUniversal features of the resultant non-equilibrium layers are predicted. Two\ncases are considered, distinguished by the value of the local monomer-surface\nsticking rate Q: chemisorption (very small Q) and physisorption (large Q).\nEarly stages of layer formation entail single chain adsorption. While single\nchain physisorption times tau_ads are typically microsecs, for chemisorbing\nchains of N units we find experimentally accessible times tau_ads = Q^{-1}\nN^{3/5}, ranging from secs to hrs. We establish 3 chemisorption universality\nclasses, determined by a critical contact exponent: zipping, accelerated\nzipping and homogeneous collapse. For dilute solutions, the mechanism is\naccelerated zipping: zipping propagates outwards from the first attachment,\naccelerated by occasional formation of large loops which nucleate further\nzipping. This leads to a transient distribution omega(s) \\sim s^{-7/5} of loop\nlengths s up to a size s_max \\approx (Q t)^{5/3} after time t. By tau_ads the\nentire chain is adsorbed. The outcome of the single chain adsorption episode is\na monolayer of fully collapsed chains. Having only a few vacant sites to adsorb\nonto, late arriving chains form a diffuse outer layer. In a simple picture we\nfind for both chemisorption and physisorption a final loop distribution\nOmega(s) \\sim s^{-11/5} and density profile c(z) \\sim z^{-4/3} whose forms are\nthe same as for equilibrium layers. In contrast to equilibrium layers, however,\nthe statistical properties of a given chain depend on its adsorption time; the\nouter layer contains many classes of chain, each characterized by different\nfraction of adsorbed monomers f. Consistent with strong physisorption\nexperiments, we find the f values follow a distribution P(f) \\sim f^{-4/5}.",
        "positive": "Configuration-tree Theoretical Calculation of the Mean-Squared\n  Displacement of Particles in Glass Formers: We report an analytical evaluation of the mean-squared displacement (MSD) of\nthe particles in glasses based on their coarse grained trajectories. The\ncalculation is conducted by means of a local random configuration-tree theory\nthat was recently proposed by one of us [C.-H. Lam, J. Stat. Mech.\n\\textbf{2018}, 023301 (2018)]. Results are compared with the numerical\nsimulations of a lattice glass model, and good quantitative agreement has been\nobtained over a wide range of temperatures in the entire region of time with\nvirtually no free parameters. To the best of our knowledge, the calculation is\nthe first in its kind."
    },
    {
        "anchor": "Single-Molecule Morphology of Topologically Digested Olympic Networks: The kinetoplast DNA (kDNA) is the archetype of a two-dimensional Olympic\nnetwork, composed of thousands of DNA minicircles and found in the\nmitochondrion of certain parasites. The evolution, replication and\nself-assembly of this structure are fascinating open questions in biology that\ncan also inform us how to realise synthetic Olympic networks in vitro. To\nobtain a deeper understanding of the structure and assembly of kDNA networks,\nwe sequenced the Crithidia fasciculata kDNA genome and performed\nhigh-resolution Atomic Force Microscopy (AFM) and analysis of kDNA networks\nthat had been partially digested by selected restriction enzymes. We discovered\nthat these topological perturbations lead to networks with significantly\ndifferent geometrical features and morphologies with respect to the unperturbed\nkDNA, and that these changes are strongly dependent on the class of DNA circles\ntargeted by the restriction enzymes. Specifically, cleaving maxicircles leads\nto a dramatic reduction in network size once adsorbed onto the surface, whilst\ncleaving both maxicircles and a minor class of minicircles yields non-circular\nand deformed structures. We argue that our results are a consequence of a\nprecise positioning of the maxicircles at the boundary of the network, and we\ndiscuss our findings in the context of kDNA biogenesis, design of artificial\nOlympic networks and detection of in vivo perturbations.",
        "positive": "Random Diffusion Model with Structure Corrections: The random diffusion model is a continuum model for a conserved scalar\ndensity field driven by diffusive dynamics where the bare diffusion coefficient\nis density dependent. We generalize the model from one with a sharp wavenumber\ncutoff to one with a more natural large-wavenumber cutoff. We investigate\nwhether the features seen previously -- namely a slowing down of the system and\nthe development of a prepeak in the dynamic structure factor at a wavenumber\nbelow the first structure peak -- survive in this model. A method for\nextracting information about a hidden prepeak in experimental data is\npresented."
    },
    {
        "anchor": "Deformation Modes of a Packing of Rigid Grains: Rotation,\n  Counter-rotation, dislocation field: The properties of the processes of deformation of a packing of rigid grains\nare analysed when the exact distribution of the normal forces at contacts is\nknown. Importance of grain rotation and of counter-rotation of adjacent grains\nis stressed. It is shown that all deformation modes form an incomplete\nvectorial space D. This allows the statistics of fluctuation to be determined.\nParallel with anti-ferromagnetism is then drawn and frustration of rotation is\nshown to be the leading dissipating mechanism. However this does not allow\nmaking the parallel with spinglass due to the structure of the space of\ndeformation modes which is vectorial, which ensures response linearity. In\norder to demonstrate experimentally the validity of the approach and the\nexistence of the incomplete vectorial space of deformation, experimental\nexamples are studied starting from regular arrays. They do demonstrate the\nmechanism of counter-rotation and the existence of the vectorial space of\ndeformation. This theory is applied to compare different experiment and\nsimulation results on the deformation of square and triangular lattices of\nrods, which can only be done through a statistical approach based on existence\nof different modes of deformation. Non linear behaviour of the modes is\ndemonstrated experimentally; link with the continuous theory of dislocation is\nmade. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn",
        "positive": "Optical trapping and critical Casimir forces: Critical Casimir forces emerge between objects, such as colloidal particles,\nwhenever their surfaces spatially confine the fluctuations of the order\nparameter of a critical liquid used as a solvent. These forces act at short but\nmicroscopically large distances between these objects, reaching often hundreds\nof nanometers. Keeping colloids at such distances is a major experimental\nchallenge, which can be addressed by the means of optical tweezers. Here, we\nreview how optical tweezers have been successfully used to quantitatively study\ncritical Casimir forces acting on particles in suspensions. As we will see, the\nuse of optical tweezers to experimentally study critical Casimir forces can\nplay a crucial role in developing nano-technologies, representing an innovative\nway to realize self-assembled devices at the nano- and microscale."
    },
    {
        "anchor": "Factors governing fibrillogenesis of polypeptide chains: Using lattice models we explore the factors that determine the tendencies of\npolypeptide chains to aggregate by exhaustively sampling the sequence and\nconformational space. The morphologies of the fibril-like structures and the\ntime scales ($\\tau_{fib}$) for their formation depend on a balance between\nhydrophobic and coulomb interactions. The extent of population of an ensemble\nof \\textbf{N$^*$} structures, which are fibril-prone structures in the spectrum\nof conformations of an isolated protein, is the major determinant of\n$\\tau_{fib}$. This observation is used to determine the aggregating sequences\nby exhaustively exploring the sequence space, thus providing a basis for genome\nwide search of fragments that are aggregation prone.",
        "positive": "Theory and simulation for equilibrium glassy dynamics in cellular Potts\n  model of confluent biological tissue: Glassy dynamics in a confluent monolayer is indispensable in morphogenesis,\nwound healing, bronchial asthma, and many others; a detailed theoretical\nframework for such a system is, therefore, important. Vertex model (VM)\nsimulations have provided crucial insights into the dynamics of such systems,\nbut their nonequilibrium nature makes it difficult for theoretical development.\nCellular Potts model (CPM) of confluent monolayer provides an alternative model\nfor such systems with a well-defined equilibrium limit. We combine numerical\nsimulations of CPM and an analytical study based on one of the most successful\ntheories of equilibrium glass, the random first order transition theory, and\ndevelop a comprehensive theoretical framework for a confluent glassy system. We\nfind that the glassy dynamics within CPM is qualitatively similar to that in\nVM. Our study elucidates the crucial role of geometric constraints in bringing\nabout two distinct regimes in the dynamics, as the target perimeter $P_0$ is\nvaried. The unusual sub-Arrhenius relaxation results from the distinctive\ninteraction potential arising from the perimeter constraint in such systems.\nFragility of the system decreases with increasing $P_0$ in the low-$P_0$\nregime, whereas the dynamics is independent of $P_0$ in the other regime. The\nrigidity transition, found in VM, is absent within CPM; this difference seems\nto come from the nonequilibrium nature of the former. We show that CPM captures\nthe basic phenomenology of glassy dynamics in a confluent biological system via\ncomparison of our numerical results with existing experiments on different\nsystems."
    },
    {
        "anchor": "Electric-field-induced oscillations in ionic fluids: a unified\n  formulation of modified Poisson-Nernst-Planck models and its relevance to\n  correlation function analysis: We theoretically investigate an electric-field-driven system of charged\nspheres as a primitive model of concentrated electrolytes under an applied\nelectric field. First, we provide a unified formulation for the stochastic\ncharge and density dynamics of the electric-field-driven primitive model using\nthe stochastic density functional theory (DFT). The stochastic DFT integrates\nvarious frameworks of the equilibrium and dynamic DFTs, the liquid state\ntheory, and the field-theoretic approach, which allows us to justify in a\nunified manner various modifications previously made for the\nPoisson-Nernst-Planck model. Next, we consider stationary density-density and\ncharge-charge correlation functions of the primitive model with a static\nelectric field. We focus on an electric-field-induced synchronization between\nthe emergence of density and charge oscillations, or the crossover from\nmonotonic to oscillatory decay of density-density and charge-charge\ncorrelations. The correlation function analysis demonstrates the appearance of\nstripe states formed by segregation bands perpendicular to the external field.\nWe also predict the following: (i) the electric-field-induced crossover occurs\nprior to the conventional Kirkwood crossover without an applied electric field,\nand (ii) the ion concentration dependence of the decay lengths at the\nelectric-field-induced crossovers bears a similarity to the underscreening\nbehavior found by simulation and theoretical studies on the oscillatory decay\nlength in equilibrium.",
        "positive": "Conformations of Circular DNA: We examine the elastic model of short circular DNA. We obtain analytic\nexpressions for configurations, elastic energy, twist and linking number of our\nsolutions. We find the onset of the plectonemic transition. We suggest ways to\nuse our formalism to describe other elastic models, and to improve the current\nfinite-element-analysis methods. We estimate the effect of thermodynamic\nfluctuations."
    },
    {
        "anchor": "Anomalous tumbling of colloidal ellipsoids in Poiseuille flows: Shear flows cause aspherical colloidal particles to tumble so that their\norientations trace out complex trajectories known as Jeffery orbits. The\nJeffery orbit of a prolate ellipsoid is predicted to align the particle's\nprincipal axis preferentially in the plane transverse to the axis of shear.\nHolographic microscopy measurements reveal instead that colloidal ellipsoids'\ntrajectories in Poiseuille flows strongly favor an orientation inclined by\nroughly $\\pi/8$ relative to this plane. This anomalous observation is\nconsistent with at least two previous reports of colloidal rods and dimers of\ncolloidal spheres in Poiseuille flow and therefore appears to be a generic, yet\nunexplained feature of colloidal transport at low Reynolds numbers.",
        "positive": "Phase-field model for Hele-Shaw flows with arbitrary viscosity contrast.\n  I. Theoretical approach: We present a phase-field model for the dynamics of the interface between two\ninmiscible fluids with arbitrary viscosity contrast in a rectangular Hele-Shaw\ncell. With asymptotic matching techniques we check the model to yield the right\nHele-Shaw equations in the sharp-interface limit and compute the corrections to\nthese equations to first order in the interface thickness. We also compute the\neffect of such corrections on the linear dispersion relation of the planar\ninterface. We discuss in detail the conditions on the interface thickness to\ncontrol the accuracy and convergence of the phase-field model to the limiting\nHele-Shaw dynamics. In particular, the convergence appears to be slower for\nhigh viscosity contrasts."
    },
    {
        "anchor": "Disordered jammed packings of frictionless spheres: At low volume fraction, disordered arrangements of frictionless spheres are\nfound in un--jammed states unable to support applied stresses, while at high\nvolume fraction they are found in jammed states with mechanical strength. Here\nwe show, focusing on the hard sphere zero pressure limit, that the transition\nbetween un-jammed and jammed states does not occur at a single value of the\nvolume fraction, but in a whole volume fraction range. This result is obtained\nvia the direct numerical construction of disordered jammed states with a volume\nfraction varying between two limits, $0.636$ and $0.646$. We identify these\nlimits with the random loose packing volume fraction $\\rl$ and the random close\npacking volume fraction $\\rc$ of frictionless spheres, respectively.",
        "positive": "Glass Transition for Driven Granular Fluids: We investigate the dynamics of a driven system of dissipative hard spheres in\nthe framework of mode-coupling theory. The dissipation is modeled by normal\nrestitution, and driving is applied to individual particles in the bulk. In\nsuch a system, a glass transition is predicted for a finite transition density.\nFor increasing inelasticity, the transition shifts to higher densities. Despite\nthe strong driving at high dissipation, the transition persists up to the limit\nof totally inelastic normal restitution."
    },
    {
        "anchor": "Critical adsorption on non-spherical colloidal particles: We consider a non-spherical colloidal particle immersed in a fluid close to\nits critical point. The temperature dependence of the corresponding order\nparameter profile is calculated explicitly. We perform a systematic expansion\nof the order parameter profile in powers of the local curvatures of the surface\nof the colloidal particle. This curvature expansion reduces to the short\ndistance expansion of the order parameter profile in the case that the solvent\nis at the critical composition.",
        "positive": "Velocity Distribution and Cumulants in the Unsteady Uniform Longitudinal\n  Flow of a Granular Gas: The uniform longitudinal flow is characterized by a linear longitudinal\nvelocity field $u_x(x,t)=a(t)x$, where $a(t)={a_0}/({1+a_0t})$ is the strain\nrate, a uniform density $n(t)\\propto a(t)$, and a uniform granular temperature\n$T(t)$. Direct simulation Monte Carlo solutions of the Boltzmann equation for\ninelastic hard spheres are presented for three (one positive and two negative)\nrepresentative values of the initial strain rate $a_0$. Starting from different\ninitial conditions, the temporal evolution of the reduced strain rate\n$a^*\\propto a_0/\\sqrt{T}$, the non-Newtonian viscosity, the second and third\nvelocity cumulants, and three independent marginal distribution functions has\nbeen recorded. Elimination of time in favor of the reduced strain rate $a^*$\nshows that, after a few collisions per particle, different initial states are\nattracted to common \"hydrodynamic\" curves. Strong deviations from Maxwellian\nproperties are observed from the analysis of the cumulants and the marginal\ndistributions."
    },
    {
        "anchor": "Self-Assembly in Mixtures of Polymers and Small Associating Molecules: The interaction between a flexible polymer in good solvent and smaller\nassociating solute molecules such as amphiphiles (surfactants) is considered\ntheoretically. Attractive correlations, induced in the polymer because of the\ninteraction, compete with intra-chain repulsion and eventually drive a joint\nself-assembly of the two species, accompanied by partial collapse of the chain.\nResults of the analysis are found to be in good agreement with experiments on\nthe onset of self-assembly in diverse polymer-surfactant systems. The threshold\nconcentration for self-assembly in the mixed system (critical aggregation\nconcentration, cac) is always lower than the one in the polymer-free solution\n(critical micelle concentration, cmc). Several self-assembly regimes are\ndistinguished, depending on the effective interaction between the two species.\nFor strong interaction, corresponding experimentally to oppositely charged\nspecies, the cac is much lower than the cmc. It increases with ionic strength\nand depends only weakly on polymer charge. For weak interaction, the cac is\nlower but comparable to the cmc, and the two are roughly proportional over a\nwide range of cmc values. Association of small molecules with amphiphilic\npolymers exhibiting intra-chain aggregation (polysoaps) is gradual, having no\nsharp onset.",
        "positive": "Dielectrophoresis of nanocolloids: a molecular dynamics study: Dielectrophoresis (DEP), the motion of polarizable particles in non-uniform\nelectric fields, has become an important tool for the transport, separation,\nand characterization of microparticles in biomedical and nanoelectronics\nresearch. In this article we present, to our knowledge, the first molecular\ndynamics simulations of DEP of nanometer-sized colloidal particles. We\nintroduce a simplified model for polarizable nanoparticles, consisting of a\nlarge charged macroion and oppositely charged microions, in an explicit\nsolvent. The model is then used to study DEP motion of the particle at\ndifferent combinations of temperature and electric field strength. In accord\nwith linear response theory, the particle drift velocities are shown to be\nproportional to the DEP force. Analysis of the colloid DEP mobility shows a\nclear time dependence, demonstrating the variation of friction under\nnon-equilibrium. The time dependence of the mobility further results in an\napparent weak variation of the DEP displacements with temperature."
    },
    {
        "anchor": "Density fluctuations of polymers in disordered media: We study self avoiding random walks in an environment where sites are\nexcluded randomly, in two and three dimensions. For a single polymer chain, we\nstudy the statistics of the time averaged monomer density and show that these\nare well described by multifractal statistics. This is true even far from the\npercolation transition of the disordered medium. We investigate solutions of\nchains in a disordered environment and show that the statistics cease to be\nmultifractal beyond the screening length of the solution.",
        "positive": "Domain Growth Kinetics in a Cell-sized Liposome: We investigated the kinetics of domain growth on liposomes consisting of a\nternary mixture (unsaturated phospholipid, saturated phospholipid, and\ncholesterol) by temperature jump. The domain growth process was monitored by\nfluorescence microscopy, where the growth was mediated by the fusion of domains\nthrough the collision. It was found that an average domain size r develops with\ntime t as r ~ t^0.15, indicating that the power is around a half of the\ntheoretical expectation deduced from a model of Brownian motion on a\n2-dimensional membrane. We discuss the mechanism of the experimental scaling\nbehavior by considering the elasticity of the membrane."
    },
    {
        "anchor": "Active fluidization in dense glassy systems: Dense soft glasses show strong collective caging behavior at sufficiently low\ntemperatures. Using molecular dynamics simulations of a model glass former, we\nshow that the incorporation of activity or self-propulsion, f0, can induce cage\nbreaking and fluidization, resulting in a disappearance of the glassy phase\nbeyond a critical f0 . The diffusion coefficient crosses over from being\nstrongly to weakly temperature dependent as f0 is increased. In addition, we\ndemonstrate that activity induces a crossover from a fragile to a strong glass\nand a tendency for clustering of active particles. Our results are of direct\nrelevance to the collective dynamics of dense active colloidal glasses and to\nrecent experiments on tagged particle diffusion in living cells.",
        "positive": "Are leaves optimally designed for self-support? An investigation on\n  giant monocots: Leaves are the organs that intercept light and create photosynthesis.\nEfficient light interception is provided by leaves oriented orthogonal to most\nof the sun rays. Except in the polar regions, this means orthogonal to the\ndirection of acceleration due to gravity, or simply horizontal. The leaves of\nalmost all terrestrial plants grow in a gravity field that tends to bend them\ndownward and therefore may counteract light interception. Plants thus allocate\nbiomass for self-support in order to maintain their leaves horizontal. To\ncompete with other species (inter-species competition), as well as other\nindividuals within the same species (intra-species competition), self-support\nmust be achieved with the least biomass produced. This study examines to what\nextent leaves are designed to self-support. We show here that a basic\nmechanical model provides the optimal dimensions of a leaf for light\ninterception and self-support. These results are compared to measurements made\non leaves of various giant monocot species,especially palm trees and banana\ntrees. The comparison between experiments and model predictions shows that the\nlonger palms are optimally designed for self-support whereas shorter leaves are\nshaped predominantly by other parameters of selection."
    },
    {
        "anchor": "Fraction of clogging configurations sampled by granular hopper flow: We measure the fraction $F$ of flowing grain configurations that precede a\nclog, based on the average mass discharged between clogging events for various\naperture geometries. By tilting the hopper, we demonstrate that $F$ is a\nfunction of the hole area projected in the direction of the exiting grain\nvelocity. By varying the length of slits, we demonstrate that grains clog in\nthe same manner as if they were flowing out of a set of smaller independent\ncircular openings. The collapsed data for $F$ can be fit to a decay that is\nexponential in hole width raised to the power of the system dimensionality.\nThis is consistent with a simple model in which individual grains near the hole\nhave a large but constant probability to precede a clog. Such a picture implies\nthat there is no sharp clogging transition, and that all hoppers have a nonzero\nprobability to clog. See Supplemental Material for models of clogging as a\ndiscrete Poisson process, and for resulting alternative measures of l based on\nthe standard deviation of the discharge mass distribution.",
        "positive": "Modeling Smectic Layers in Confined Geometries: Order Parameter and\n  Defects: We identify problems with the standard complex order parameter formalism for\nsmectic-A (SmA) liquid crystals, and discuss possible alternative descriptions\nof smectic order. In particular, we suggest an approach based on the real\nsmectic density variation rather than a complex order parameter. This approach\ngives reasonable numerical results for the smectic layer configuration and\ndirector field in sample geometries, and can be used to model smectic liquid\ncrystals under nanoscale confinement for technological applications."
    },
    {
        "anchor": "Stability Puzzles in Phage Lambda: The lysogeny maintenance switch in phage lambda is one of the simplest\nexamples on the molecular level of computation, command and control in a living\nsystem. If, following infection of the bacterium E. coli, the virus enters the\nlysogenic pathway, it represses its developmental functions, and integrates its\nDNA into the host chromosome. In this state the prophage may be passively\nreplicated for many generations of E. coli. In fact, this repressed state is\nintrinsically more stable than the gene encoding the repressor. We develop a\nmathematical formalism to predict the stability of such epigenetic states from\naffinities of the molecular components. We apply the model to the behavior of\nrecently published mutants at the right operator complex of lambda, and find\nthat the reported stability indicates that the current view of the switch is\nincomplete. The approach described here should be generally applicable to the\nstability of expressed states",
        "positive": "Localized and Delocalized Charge Transport in Single-Wall\n  Carbon-Nanotube Mats: We measured the complex dielectric constant in mats of single-wall\ncarbon-nanotubes between 2.7 K and 300 K up to 0.5 THz. The data are well\nunderstood in a Drude approach with a negligible temperature dependence of the\nplasma frequency (omega_p) and scattering time (tau) with an additional\ncontribution of localized charges. The dielectric properties resemble those of\nthe best ''metallic'' polypyrroles and polyanilines. The absence of metallic\nislands makes the mats a relevant piece in the puzzle of the interpretation of\ntau and omega_p in these polymers."
    },
    {
        "anchor": "Time-dependent invasion laws for a liquid-liquid displacement system: Capillary-driven flow of fluids occurs frequently in nature and has a wide\nrange of technological applications in the fields of industry, agriculture,\nmedicine, biotechnology, and microfluidics. By using the Onsager variational\nprinciple, we propose a model to systematically study the capillary imbibition\nin titled tubes, and find different laws of time-dependent capillary invasion\nlength for liquid-liquid displacement system other than Lucas-Washburn type\nunder different circumstances. The good agreement between our model and\nexperimental results shows that the imbibition dynamics in a capillary tube\nwith a prefilled liquid slug can be well captured by the dynamic equation\nderived in this paper. Our results bear important implications for macroscopic\ndescriptions of multiphase flows in microfluidic systems and porous media.",
        "positive": "Stability and interactions of nanocolloids at fluid interfaces: effects\n  of capillary waves and line tensions: We analyze the effective potential for nanoparticles trapped at a fluid\ninterface within a simple model which incorporates surface and line tensions as\nwell as a thermal average over interface fluctuations (capillary waves). For a\nsingle colloid, a reduced steepness of the potential well hindering movements\nout of the interface plane compared to rigid interface models is observed, and\nan instability of the capillary wave partition sum in case of negative line\ntensions is pointed out. For two colloids, averaging over the capillary waves\nleads to an effective Casimir--type interaction which is long--ranged,\npower-like in the inverse distance but whose power sensitively depends on\npossible restrictions of the colloid degress of freedom. A nonzero line tension\nleads to changes in the magnitude but not in the functional form of the\neffective potential asymptotics."
    },
    {
        "anchor": "The Solvophobic Solvation and Interaction of Small Apolar Particles in\n  Imidazolium-Based Ionic Liquids is Characterized by\n  Enthalpy-/Entropy-Compensation: We report results of molecular dynamics simulations characterizing the\nsolvation and interaction of small apolar particles such as methane and Xenon\nin imidazolium-based ionic liquids (ILs). The simulations are able to reproduce\nsemi-quantitatively the anomalous temperature dependence of the solubility of\napolar particles in the infinite dilution regime. We observe that the\n``solvophobic solvation'' of small apolar particles in ILs is governed by\ncompensating entropic and enthalpic contributions, very much like the\nhydrophobic hydration of small apolar particles in liquid water. In addition,\nour simulations clearly indicate that the solvent mediated interaction of\napolar particles dissolved in ILs is similarly driven by compensating\nenthalpic/entropic contributions, making the ``solvophobic interaction''\nthermodynamically analogous to the hydrophobic interaction.",
        "positive": "Nematic director fields and topographies of shells of revolution: We solve the forward and inverse problems associated with the transformation\nof flat sheets to surfaces of revolution with non-trivial topography, including\nGaussian curvature, without a stretch elastic cost. We deal with systems\nslender enough to have a small bend energy cost. Shape change is induced by\nlight or heat causing contraction along a non-uniform director field in the\nplane of an initially flat nematic sheet. The forward problem is, given a\ndirector distribution, what shape is induced? Along the way, we determine the\nGaussian curvature and the evolution with induced mechanical deformation of the\ndirector field and of material curves in the surface (proto-radii) that will\nbecome radii in the final surface. The inverse problem is, given a target\nshape, what director field does one need to specify? Analytic examples of\ndirector fields are fully calculated that will, for specific deformations,\nyield catenoids and paraboloids of revolution. The general prescription is\ngiven in terms of an integral equation."
    },
    {
        "anchor": "Modeling the phase behavior of polydisperse rigid rods with attractive\n  interactions, with applications to SWNTs in super acids: The phase behavior of rodlike molecules with polydisperse length and\nsolvent-mediated attraction and repulsion is described by an extension of the\nOnsager theory for rigid rods. A phenomenological square-well potential is used\nto model these long-range interactions, and the model is used to compute phase\nseparation and length fractionation as a function of well depth and rod\nconcentration. The model closely captures experimental data points for\nisotropic/liquid crystalline phase coexistence of single-walled carbon\nnanotubes (SWNTs) in superacids. The model also predicts that the\nisotropic-biphasic boundary approaches zero as acid strength diminishes, with\nthe possibility of coexistence of isotropic and liquid crystalline phases at\nvery low concentrations; this counterintuitive prediction is confirmed\nexperimentally. Experimental deviations from classical theories for rodlike\nliquid crystals are explained in terms of polydispersity and the balance\nbetween short range repulsion and long range attractions. The predictions of\nthe model also hold practical import for applications of SWNT/superacid\nsolutions, particularly in the processing of fibers and films from liquid\ncrystalline SWNT/superacid mixtures.",
        "positive": "Poisson-Boltzmann cell model for heterogeneously charged colloids: We introduce the Poisson-Boltzmann cell model for spherical colloidal\nparticles with a heterogeneous surface charge distribution. This model is\nobtained by generalizing existing cell models for mixtures of homogeneously\ncharged colloidal spheres. Our new model has similar features as Onsager's\nsecond-virial theory for liquid crystals, but it predicts no orientational\nordering if there is no positional ordering. This implies that all phases of\nheterogeneously charged colloids that are liquid-like with respect to\ntranslational degrees of freedom are also isotropic with respect to particle\norientation."
    },
    {
        "anchor": "Lateral trapping of DNA inside a voltage gated nanopore: The translocation of a short DNA fragment through a nanopore is addressed\nwhen the perforated membrane contains an embedded electrode. Accurate numerical\nsolutions of the coupled Poisson, Nernst-Planck, and Stokes equations for a\nrealistic, fully three-dimensional setup as well as analytical approximations\nfor a simplified model are worked out. By applying a suitable voltage to the\nmembrane electrode, the DNA can be forced to preferably traverse the pore\neither along the pore axis or at a small but finite distance from the pore\nwall.",
        "positive": "Thermodynamic anomalies in a lattice model of water: Solvation\n  properties: We investigate a lattice-fluid model of water, defined on a 3-dimensional\nbody-centered cubic lattice. Model molecules possess a tetrahedral symmetry,\nwith four equivalent bonding arms. The model is similar to the one proposed by\nRoberts and Debenedetti [J. Chem. Phys. 105, 658 (1996)], simplified by\nremoving distinction between \"donors\" and \"acceptors\". We focus on solvation\nproperties, mainly as far as an ideally inert (hydrophobic) solute is\nconcerned. As in our previous analysis, devoted to neat water [J. Chem. Phys.\n121, 11856 (2004)], we make use of a generalized first order approximation on a\ntetrahedral cluster. We show that the model exhibits quite a coherent picture\nof water thermodynamics, reproducing qualitatively several anomalous properties\nobserved both in pure water and in solutions of hydrophobic solutes. As far as\nsupercooled liquid water is concerned, the model is consistent with the second\ncritical point scenario."
    },
    {
        "anchor": "Cooling by heating a nanodroplet - proof of concept: Recently [3] predicted the existence of an intriguing new phenomenon. It was\nshown that if temperature is suddenly raised at the surface of a sphere the\ntemperature in the interior initially decreases. The authors of [3] gave a\nthorough analysis explaining the physics leading to this remarkable effect.\nThey linked the existence of the phenomenon to the subtle thermomechanical\ncoupling between displacement and temperature in a sphere that is able to\nexpand freely and showed that the effect is expected to be largest close to the\nglasstransition temperature of the perturbed material. The prediction was based\non the assumption of quasi-elasticity where the sample is much smaller than the\nwavelength of acoustic waves at frequencies of relevance. Being in the inertia\nfree limit they could ignore the acceleration term in the thermoviscoelastic\nequations of motion. Here we give the first empirical proof of existence of the\neffect by performing molecular dynamics simulations of a supercooled\nKob-Andersen binary mixture of Lennard-Jones particles forming a droplet\nconsisting of 500.000 particles. We show that the phenomenon is real even when\ninertia cannot be disregarded.",
        "positive": "Structuring Colloidal Gels via Micro-Bubble Oscillations: Locally (re)structuring colloidal gels $\\unicode{x2013}$ micron-sized\nparticles forming a connected network with arrested dynamics $\\unicode{x2013}$\nenables precise tuning of the micromechanical and -rheological properties of\nthe system. A recent experimental study [B. Saint-Michel, G. Petekidis, and V.\nGarbin, Soft Matter $\\boldsymbol{18}$, 2092 (2022)] showed that rapid\nrestructuring can occur by acoustically modulating an embedded microbubble.\nHere, we perform Brownian dynamics simulations to understand the mechanical\neffect of an oscillating microbubble on the structure of the embedding\ncolloidal gel. Our simulations reveal a hexagonal-close-packed restructuring in\na range that is comparable to the amplitude of the oscillations. However, we\nwere unable to reproduce the unexpectedly long-ranged modification of the gel\nstructure $\\unicode{x2013}$ dozens of amplitudes $\\unicode{x2013}$ observed in\nexperiment. This suggests including long-ranged effects, such as fluid flow,\nshould be considered in future work."
    },
    {
        "anchor": "Effective medium theory of random regular networks: Disordered spring networks can exhibit rigidity transitions, due to either\nthe removal of materials in over-constrained networks or the application of\nstrain in under-constrained ones. While an effective medium theory (EMT) exists\nfor the former, there is none for the latter. We, therefore, formulate an EMT\nfor random regular networks, under-constrained spring networks with purely\ngeometrical disorder, to predict their stiffness via the distribution of\ntensions. We find a linear dependence of stiffness on strain in the rigid phase\nand a nontrivial dependence on both the mean and standard deviation of the\ntension distribution. While EMT does not yield highly accurate predictions of\nshear modulus due to spatial heterogeneities, the noninvasiveness of this EMT\nmakes it an ideal starting point for experimentalists quantifying the mechanics\nof such networks.",
        "positive": "Growth mechanism of polymer membranes obtained by H-bonding across\n  immiscible liquid interfaces: Complexation of polymers at liquid interfaces is an emerging technique to\nproduce all-liquid printable and self-healing devices and membranes. It is\ncrucial to control the assembly process but the mechanisms at play remain\nunclear. Using two different reflectometric methods, we investigate the\nspontaneous growth of H-bonded PPO-PMAA membranes at a flat liquid-liquid\ninterface. We find that the membrane thickness h grows with time t as\nh~t^(1/2), which is reminiscent of a diffusion-limited process. However,\ncounter-intuitively, we observe that this process is faster as the PPO molar\nmass increases. We are able to rationalize these results with a model which\nconsiders the diffusion of the PPO chains within the growing membrane. The\narchitecture of the latter is described as a gel-like porous network, with a\npore size much smaller than the radius of the diffusing PPO chains, thus\ninducing entropic barriers that hinder the diffusion process. From the\ncomparison between the experimental data and the result of the model, we\nextract some key piece of information about the microscopic structure of the\nmembrane. This study opens the route toward the rational design of\nself-assembled membranes and capsules with optimal properties."
    },
    {
        "anchor": "Density functional theory of gas-liquid phase separation in dilute\n  binary mixtures: We examine statics and dynamics of phase-separated states of dilute binary\nmixtures using density functional theory. In our systems, the difference in the\nsalvation chemical potential $\\Delta\\mu_s$ between liquid and gas is\nconsiderably larger than the thermal energy $k_BT$ for each solute particle and\nthe attractive interaction among the solute particles is weaker than that among\nthe solvent particles. In these conditions, the saturated vapor pressure\nincreases by an amount equal to the solute density in liquid multiplied by the\nlarge factor $k_BT \\exp(\\Delta\\mu_s/k_BT)$. As a result, phase separation is\ninduced at low solute densities in liquid and the new phase remains in gaseous\nstates, while the liquid pressure is outside the coexistence curve of the\nsolvent. This explains the widely observed formation of stable nanobubbles in\nambient water with a dissolved gas. We calculate the density and stress\nprofiles across planar and spherical interfaces, where the surface tension\ndecreases with increasing the interfacial solute adsorption. We realize stable\nsolute-rich bubbles with radius about 30 nm, which minimize the free energy\nfunctional. We then study dynamics around such a bubble after a decompression\nof the surrounding liquid, where the bubble undergoes a damped oscillation. In\naddition, we present some exact and approximate expressions for the surface\ntension and the interfacial stress tensor.",
        "positive": "Pulling an adsorbed polymer chain off a solid surface: The thermally assisted detachment of a self-avoiding polymer chain from an\nadhesive surface by an external force applied to one of the chain ends is\ninvestigated. We perform our study in the \"fixed height\" statistical ensemble\nwhere one measures the fluctuating force, exerted by the chain on the last\nmonomer when a chain end is kept fixed at height $h$ over the solid plane at\ndifferent adsorption strength $\\epsilon$. The phase diagram in the $h -\n\\epsilon$ plane is calculated both analytically and by Monte Carlo simulations.\nWe demonstrate that in the vicinity of the polymer desorption transition a\nnumber of properties like fluctuations and probability distribution of various\nquantities behave differently, if $h$ rather than $f$ is used as an independent\ncontrol parameter."
    },
    {
        "anchor": "Predicting heteropolymer interactions: demixing and hypermixing of\n  disordered protein sequences: Cells contain multiple condensates which spontaneously form due to the\nheterotypic interactions between their components. Although the proteins and\ndisordered region sequences that are responsible for condensate formation have\nbeen extensively studied, the rule of interactions between the components that\nallow demixing, i.e., the coexistence of multiple condensates, is yet to be\nelucidated. Here we construct an effective theory of the interaction between\nheteropolymers by fitting it to the molecular dynamics simulation results\nobtained for more than 200 sequences sampled from the disordered regions of\nhuman proteins. We find that the sum of amino acid pair interactions across two\nheteropolymers predicts the Boyle temperature qualitatively well, which can be\nquantitatively improved by the dimer pair approximation, where we incorporate\nthe effect of neighboring amino acids in the sequences. The improved theory,\ncombined with the finding of a metric that captures the effective interaction\nstrength between distinct sequences, allowed the selection of up to three\ndisordered region sequences that demix with each other in multicomponent\nsimulations, as well as the generation of artificial sequences that demix with\na given sequence. The theory points to a generic sequence design strategy to\ndemix or hypermix thanks to the low dimensional nature of the space of the\ninteractions that we identify. As a consequence of the geometric arguments in\nthe space of interactions, we find that the number of distinct sequences that\ncan demix with each other is strongly constrained, irrespective of the choice\nof the coarse-grained model. Altogether, we construct a theoretical basis for\nmethods to estimate the effective interaction between heteropolymers, which can\nbe utilized in predicting phase separation properties as well as rules of\nassignment in the localization and functions of disordered proteins.",
        "positive": "Order and disorder in columnar joints: Columnar joints are three-dimensional fracture networks that form in cooling\nbasalt and several other media. The network organizes itself into ordered,\nmostly hexagonal columns. The same pattern can be observed on a smaller scale\nin desiccating starch. We show how surface boundary conditions in the\ndesiccation of starch affect the formation of columnar joints. Under constant\ndrying power conditions, we find a power law dependence of columnar\ncross-sectional area with depth, while under constant drying rate conditions\nthis coarsening is eventually halted. Discontinuous transitions in pattern\nscale can be observed under constant external conditions, which may prompt a\nreinterpretation of similar transitions found in basalt. Starch patterns are\nstatistically similar to those found in basalt, suggesting that mature columnar\njointing patterns contain inherent residual disorder, but are statistically\nscale invariant."
    },
    {
        "anchor": "Colloidal gelation with variable attraction energy: We present an approximation scheme to the master kinetic equations for\naggregation and gelation with thermal breakup in colloidal systems with\nvariable attraction energy. With the cluster fractal dimension $d_{f}$ as the\nonly phenomenological parameter, rich physical behavior is predicted. The\nviscosity, the gelation time and the cluster size are predicted in closed form\nanalytically as a function of time, initial volume fraction and attraction\nenergy by combining the reversible clustering kinetics with an approximate\nhydrodynamic model. The fractal dimension $d_{f}$ modulates the time evolution\nof cluster size, lag time and gelation time and of the viscosity. The gelation\ntransition is strongly nonequilibrium and time-dependent in the unstable region\nof the state diagram of colloids where the association rate is larger than the\ndissociation rate. Only upon approaching conditions where the initial\nassociation and the dissociation rates are comparable for all species (which is\na condition for the detailed balance to be satisfied) aggregation can occur\nwith $d_{f}=3$. In this limit, homogeneous nucleation followed by\nLifshitz-Slyozov coarsening is recovered. In this limited region of the state\ndiagram the macroscopic gelation process is likely to be driven by large\nspontaneous fluctuations associated with spinodal decomposition.",
        "positive": "Apparent Contact Angle of Droplets on Liquid Infused Surfaces: Geometric\n  Interpretation: We theoretically investigate the apparent contact angle of droplets on liquid\ninfused surfaces as a function of the relative size of the wetting ridge and\nthe deposited droplet. We provide an intuitive geometrical interpretation\nwhereby the variation in the apparent contact angle is due to the rotation of\nthe Neumann triangle. We also derive linear and quadratic corrections to the\napparent contact angle as power series expansion in terms of pressure\ndifferences between the lubricant, droplet and gas phases. These expressions\nare much simpler and more compact compared to those previously derived by\nSemprebon et al. [Soft Matter, 2017, 13, 101-110]."
    },
    {
        "anchor": "Mapping cell cortex rheology to tissue rheology, and vice-versa: The mechanics of biological tissues mainly proceeds from the cell cortex\nrheology. A direct, explicit link between cortex rheology and tissue rheology\nremains lacking, yet would be instrumental in understanding how modulations of\ncortical mechanics may impact tissue mechanical behaviour. Using an ordered\ngeometry built on 3D hexagonal, incompressible cells, we build a mapping\nrelating the cortical rheology to the monolayer tissue rheology. Our approach\nshows that the tissue low frequency elastic modulus is proportional to the rest\ntension of the cortex, as expected from the physics of liquid foams as well as\nof tensegrity structures. A fractional visco-contractile cortex rheology is\npredicted to yield a high-frequency fractional visco-elastic monolayer\nrheology, where such a fractional behaviour has been recently observed\nexperimentally at each scale separately. In particular cases, the mapping may\nbe inverted, allowing to derive from a given tissue rheology the underlying\ncortex rheology. Interestingly, applying the same approach to a 2D hexagonal\ntiling fails, which suggests that the 2D character of planar cell cortex-based\nmodels may be unsuitable to account for realistic monolayer rheologies. We\nprovide quantitative predictions, amenable to experimental tests through\nstandard perturbation assays of cortex constituents, and hope to foster new,\nchallenging mechanical experiments on cell monolayers.",
        "positive": "Tuning Higher Order Structure in Colloidal Fluids: Colloidal particles self assemble into a wide range of structures under AC\nelectric fields due to induced dipolar interactions [Yethiraj and Van Blaaderen\nNature 421 513 (2003)]. Tuning the external field drives structural transitions\nin the system. Here we consider colloidal fluids comprised of such dipolar\nparticles in experiment and simulation and investigate their 2-body and\nhigher-order structure using a variety of probes. The higher--order structure\nwe probe using three-body spatial correlation functions and a many--body\napproach based on minimum energy clusters of a related system. These clusters\nexhibit a cascade of geometric transitions upon increasing the strength of the\ndipolar interaction, which are echoed in the higher--order structure of the\nconcentrated fluids we study here."
    },
    {
        "anchor": "Effect of an electric field on a Leidenfrost droplet: We experimentally investigate the effect of an electric field applied between\na Leidenfrost droplet and the heated substrate on which it is levitating. We\nquantify the electro-Leidenfrost effect by imaging the interference fringes\nbetween the liquid-vapour and vapour-substrate interfaces. The increase of the\nvoltage induces a decrease of the vapour layer thickness. Above a certain\ncritical voltage the Leidenfrost effect is suppressed and the drop starts\nboiling. Our study characterizes this way to control and/or to avoid the\nLeidenfrost effect that is undesirable in many domains such as metallurgy or\nnuclear reactor safety.",
        "positive": "Granular Brownian motion with dry friction: The interplay between Coulomb friction and random excitations is studied\nexperimentally by means of a rotating probe in contact with a stationary\ngranular gas. The granular material is independently fluidized by a vertical\nshaker, acting as a 'heat bath' for the Brownian-like motion of the probe. Two\nball bearings supporting the probe exert nonlinear Coulomb friction upon it.\nThe experimental velocity distribution of the probe, autocorrelation function,\nand power spectra are compared with the predictions of a linear Boltzmann\nequation with friction, which is known to simplify in two opposite limits: at\nhigh collision frequency, it is mapped to a Fokker-Planck equation with\nnonlinear friction, whereas at low collision frequency, it is described by a\nsequence of independent random kicks followed by friction-induced relaxations.\nComparison between theory and experiment in these two limits shows good\nagreement. Deviations are observed at very small velocities, where the real\nbearings are not well modeled by Coulomb friction."
    },
    {
        "anchor": "Tailoring the interactions between self-propelled bodies: We classify the interactions between self-propelled particles moving at a\nconstant speed from symmetry considerations. We establish a systematic\nexpansion for the two-body forces in the spirit of a multipolar expansion. This\nformulation makes it possible to rationalize most of the models introduced so\nfar within a common framework. We distinguish between three classes of physical\ninteractions: (i) potential forces, (ii) inelastic collisions and (iii)\nnon-reciprocal interactions involving polar or nematic alignment with an\ninduced field. This framework provides simple design rules for the modeling and\nthe fabrication of self-propelled bodies interacting via physical interactions.\nA class of possible interactions that should yield new phases of active matter\nis highlighted.",
        "positive": "Non-equilibrium dynamics of the glass transition: new perspectives from\n  colloidal hard spheres: A fresh approach to the data from experiments with hard sphere colloids\nyields seminal insights into the glass transition. The precise determination of\nthe fraction of particles caged by their neighbours is unprecedented and\nprovides cornerstone of our study. We show that the so-called \"dramatic\nslowing\" that accompanies super-packing is due to correlated cage fluctuations,\nrather than caging per se. Their statistics establish that the amorphous\nassemblies of caged particles are in states of self-organised criticality. The\nimplied connection between the onset of caging and the thermodynamic 1st order\nfreezing transition challenges the status quo, as does our contention that the\ndynamically critical amorphous assemblies are precursory to that transition."
    },
    {
        "anchor": "A technique for improving dispersion within polymer-glass composites\n  using polymer precipitation: Particulate reinforcement of polymeric matrices is a powerful technique for\ntailoring the mechanical and degradation properties of bioresorbable implant\nmaterials. Dispersion of inorganic particles is critical to achieving optimal\nproperties, however established techniques such as twin-screw extrusion or\nsolvent casting can have significant drawbacks including excessive thermal\ndegradation or particle agglomeration. We present a facile method for\nproduction of polymer-inorganic composites that reduces the time at elevated\ntemperature and the time available for particle agglomeration. Glass slurry was\nadded to a dissolved PLLA solution, and ethanol was added to precipitate\npolymer onto the glass particles. Characterisation of parts formed by\nsubsequent micro-injection moulding of composite precipitate revealed a\nsignificant reduction in agglomeration, with d0.9 reduced from 170 to 43\n{\\mu}m. This drastically improved the ductility ({\\epsilon}B) from 7% to 120%,\nwithout loss of strength or stiffness. The method is versatile and applicable\nto a wide range of polymer and filler materials.",
        "positive": "Charge regulation of colloidal particles in aqueous solutions: We study charge regulation of colloidal particles inside aqueous electrolyte\nsolutions. To stabilize colloidal suspension against precipitation, colloidal\nparticles are synthesized with either acidic or basic groups on their surface.\nIn contact with water these surface groups undergo proton transfer reaction,\nresulting in colloidal surface charge. The charge is determined by the\ncondition of local chemical equilibrium between hydronium ions inside the\nsolution and at the colloidal surface. We use a model of Baxter sticky spheres\nto explicitly calculate the equilibrium dissociation constants and to construct\na theory which is able to quantitatively predict the effective charge of\ncolloidal particles with either acidic or basic surface groups. The predictions\nof the theory for the model are found to be in excellent agreement with the\nresults of Monte Carlo simulations. The theory is further extended to treat\ncolloidal particles with a mixture of both acidic and basic surface groups."
    },
    {
        "anchor": "Collective rheology in quasi static shear flow of granular media: This paper is devoted to the basic question of what factors determine the\nstrain field in a quasi static granular flow. It is shown that using stress -\nstrain rate relations is not the proper way to understand quasi static\nrheology. An alternative approach is discussed where the local deformation is\nregarded as the cause of deformation in the vicinity. We suggest a continuum\nmodel where the local shear strain is proportional to its Laplacian and the\nproportionality factor is determined by the local stress. The predicted\nbehavior is tested in a three dimensional shear cell by means of computer\nsimulations. The simplicity of our setup makes it ideal to demonstrate and\nexamine the fundamental open questions of collective granular flows. The\nobserved shear profile is interpreted in the framework of the suggested model.",
        "positive": "Kovacs effect in facilitated spin models of strong and fragile glasses: We investigate the Kovacs (or crossover) effect in facilitated $f$-spin\nmodels of glassy dynamics. Although the Kovacs hump shows a behavior\nqualitatively similar for all cases we have examined (irrespective of the\nfacilitation parameter $f$ and the spatial dimension $d$), we find that the\ndependence of the Kovacs peak time on the temperature of the second quench\nallows to distinguish among different microscopic mechanisms responsible for\nthe glassy relaxation (e.g. cooperative vs defect diffusion). We also analyze\nthe inherent structure dynamics underlying the Kovacs protocol, and find that\nthe class of facilitated spin models with $d>1$ and $f>1$ shows features\nresembling those obtained recently in a realistic model of fragile glass\nforming liquid."
    },
    {
        "anchor": "The crowding effect on the melting of short DNA: Comparison with\n  experiments: We study the effect of crowders on the melting profile of homogeneous and\nheterogeneous DNA molecules. We find out the melting profile of short DNA\nmolecules and compare our findings with the experiments. We consider some\nrandom distribution of crowders along the chain, and by finding out the best\nmatch with the experiments, we attempt to identify the location of crowders in\nthe experimental findings of Ghosh \\cite{Ghosh_PNAS_2020}. We also study the\nmelting of homogeneous DNA molecules of different lengths (25, 50, 75) in the\npresence of only one crowder in the chain. By varying the location of the\ncrowder from one end to the other, we find that the melting temperature is\nsusceptible to the location of the crowder at the ends. At the same time, there\nis minimal effect on the melting temperature due to the location of the\ncrowder. {\\it In vivo}, the strength of a crowders may vary along the chain. We\nstudy the melting of long heterogeneous chain in presence of five crowders of\ndifferent strength. We find that there is a significant variation in the\nmelting process of DNA in presence of crowders of variable strength.",
        "positive": "Universality and Scaling Behaviour of Injected Power in Elastic\n  Turbulence in Worm-like Micellar Gel: We study the statistical properties of spatially averaged global injected\npower fluctuations for Taylor-Couette flow of a worm-like micellar gel formed\nby surfactant CTAT. At sufficiently high Weissenberg numbers (Wi) the shear\nrate and hence the injected power p(t) at a constant applied stress shows large\nirregular fluctuations in time. The nature of the probability distribution\nfunction (pdf) of p(t) and the power-law decay of its power spectrum are very\nsimilar to that observed in recent studies of elastic turbulence for polymer\nsolutions. Remarkably, these non-Gaussian pdfs can be well described by an\nuniversal large deviation functional form given by the Generalized Gumbel (GG)\ndistribution observed in the context of spatially averaged global measures in\ndiverse classes of highly correlated systems. We show by in-situ rheology and\npolarized light scattering experiments that in the elastic turbulent regime the\nflow is spatially smooth but random in time, in agreement with a recent\nhypothesis for elastic turbulence."
    },
    {
        "anchor": "Label-free, Spectroscopic Detection of Leaflet Composition Asymmetry in\n  Vesicles: Vibrational sum frequency scattering (SFS) has been used to study sub-micron,\ncatanionic vesicles in solution. The vesicles were synthesized from a binary\nmixture of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylsulfate\n(SDS) surfactants in deuterated water, which spontaneously assemble into\nthermodynamically stable vesicles. The stability of these vesicles is\nattributed to a surfactant concentration asymmetry between the inner and outer\nbilayer leaflets. This concentration asymmetry should be observable by SFS due\nto local inversion symmetry-breaking. Signal corresponding to the symmetric\nsulfate stretch mode of the SDS head group is observed at 1044 cm, indicating\nthat there is indeed asymmetry in the local structure of the leaflets. The\nresults indicate that it should be possible to measure the interfacial\nstructure of liposomes in aqueous solution and study in-situ processes like the\nbinding of sugars and proteins that are important for many processes in\nbiophysical chemistry.",
        "positive": "Capacitance and Structure of Electric Double Layers: Comparing Brownian\n  Dynamics and Classical Density Functional Theory: We present a study of the structure and differential capacitance of electric\ndouble layers of aqueous electrolytes. We consider Electric Double Layer\nCapacitors (EDLC) composed of spherical cations and anions in a dielectric\ncontinuum confined between a planar cathode and anode. The model system\nincludes steric as well as Coulombic ion-ion and ion-electrode interactions. We\ncompare results of computationally expensive, but \"exact\", Brownian Dynamics\n(BD) simulations with approximate, but cheap, calculations based on classical\nDensity Functional Theory (DFT). Excellent overall agreement is found for a\nlarge set of system parameters $-$ including variations in concentrations,\nionic size- and valency-asymmetries, applied voltages, and electrode separation\n$-$ provided the differences between the canonical ensemble of the BD\nsimulations and the grand-canonical ensemble of DFT are properly taken into\naccount. In particular a careful distinction is made between the differential\ncapacitance $C_N$ at fixed number of ions and $C_\\mu$ at fixed ionic chemical\npotential. Furthermore, we derive and exploit their thermodynamic relations. In\nthe future these relations are also useful for comparing and contrasting."
    },
    {
        "anchor": "A Family of Tunable Spherically-Symmetric Potentials that Span the Range\n  from Hard Spheres to Water-like Behavior: We investigate the equation of state, diffusion coefficient, and structural\norder of a family of spherically-symmetric potentials consisting of a hard core\nand a linear repulsive ramp. This generic potential has two characteristic\nlength scales: the hard and soft core diameters. The family of potentials is\ngenerated by varying their ratio, $\\lambda$. We find negative thermal expansion\n(thermodynamic anomaly) and an increase of the diffusion coefficient upon\nisothermal compression (dynamic anomaly) for $0\\leq\\lambda<6/7$. As in water,\nthe regions where these anomalies occur are nested domes in the ($T, \\rho$) or\n($T, P$) planes, with the thermodynamic anomaly dome contained entirely within\nthe dynamic anomaly dome. We calculate translational and orientational order\nparameters ($t$ and $Q_6$), and project equilibrium state points onto the ($t,\nQ_6$) plane, or order map. The order map evolves from water-like behavior to\nhard-sphere-like behavior upon varying $\\lambda$ between 4/7 and 6/7. Thus, we\ntraverse the range of liquid behavior encompassed by hard spheres ($\\lambda=1$)\nand water-like ($\\lambda\\sim4/7$) with a family of tunable\nspherically-symmetric potentials by simply varying the ratio of hard to\nsoft-core diameters. Although dynamic and thermodynamic anomalies occur almost\nacross the entire range $0\\leq\\lambda\\leq1$, water-like structural anomalies\n(i.e., decrease in both $t$ and $Q_6$ upon compression and strictly correlated\n$t$ and $Q_6$ in the anomalous region) occur only around $\\lambda=4/7$.\nWater-like anomalies in structure, dynamics and thermodynamics arise solely due\nto the existence of two length scales, orientation-dependent interactions being\nabsent by design.",
        "positive": "Universal non-phononic density of states in 2D, 3D and 4D glasses: It is now well established that structural glasses possess disorder- and\nfrustration-induced soft quasilocalized excitations, which play key roles in\nvarious glassy phenomena. Recent work has established that in model\nglass-formers in three dimensions, these non-phononic soft excitations may\nassume the form of quasilocalized, harmonic vibrational modes whose frequency\nfollows a universal density of states $D(\\omega)\\!\\sim\\!\\omega^4$,\nindependently of microscopic details, and for a broad range of glass\npreparation protocols. Here we further establish the universality of the\nnon-phononic density of vibrational modes by direct measurements in model\nstructural glasses in two dimensions and four dimensions. We also investigate\ntheir degree of localization, which is generally weaker in lower spatial\ndimensions, giving rise to a pronounced system-size dependence of the\nnon-phononic density of states in two dimensions, but not in higher dimensions.\nFinally, we identify a fundamental glassy frequency scale $\\omega_c$ above\nwhich the universal $\\omega^4$ law breaks down."
    },
    {
        "anchor": "Simulations of LiCl-Water: The Effects of Concentration and Supercooling: Aqueous solutions of LiCl are probably the most studied electrolyte solutions\nrelated to the complexity of liquid water at low temperatures. Despite the\nlarge amount of available experimental data hardly any computational studies\nwere performed on LiCl solutions in this context. In this study, we present\nmolecular dynamics simulations of LiCl-water at ambient and supercooled\nconditions spanning a large concentration range. The molecular insight gained\nprovides information on how the presence of the ions impacts the hydrogen bond\nnetwork. It is found that this influence changes appreciably when supercooled\nstates are considered. While the local structure of water molecules beyond the\nfirst hydration shells barely changes with concentration at room temperature, a\nchange is found for those molecules at low temperature. Additionally, we\nscrutinize the possibility of a phase separation in this system as indicated by\nseveral experimental studies. Our analyses do not show signs of such a phase\nseparation at 240 K, but are consistent with a possible separation at even\nlower temperatures.",
        "positive": "Interfacial Properties of Fluids Exhibiting Liquid Polyamorphism and\n  Water-Like Anomalies: It has been hypothesized that liquid polyamorphism, the existence of multiple\namorphous states in a single component substance, may be caused by molecular or\nsupramolecular interconversion. A simple microscopic model [Caupin and\nAnisimov, Phys. Rev. Lett., 127, 185701, (2021)] introduces interconversion in\na compressible binary lattice to generate various thermodynamic scenarios for\nfluids that exhibit liquid polyamorphism and/or water-like anomalies. Using\nthis model, we demonstrate the dramatic effects of interconversion on the\ninterfacial properties. In particular, we find that the liquid-vapor surface\ntension exhibits either an inflection point or two extrema in its temperature\ndependence. Correspondingly, we observe anomalous behavior of the interfacial\nthickness and a significant shift in the location of the concentration profile\nwith respect to the location of the density profile."
    },
    {
        "anchor": "Nuclear Magnetic Resonance studies of DNP-ready trehalose obtained by\n  solid state mechanochemical amorphization: $^1$H nuclear spin-lattice relaxation and Dynamic Nuclear Polarization (DNP)\nhave been studied in amorphous samples of trehalose sugar doped with TEMPO\nradicals by means of mechanical milling, in the 1.6 K $\\div$ 4.2 K temperature\nrange. The radical concentration was varied between 0.34 and 0.81 $\\%$. The\nhighest polarization of 15 \\% at 1.6 K, observed in the sample with\nconcentration $0.50 \\%$, is of the same order of magnitude of that reported in\nstandard frozen solutions with TEMPO. The temperature and concentration\ndependence of the spin-lattice relaxation rate $1/T_{\\text{1}}$, dominated by\nthe coupling with the electron spins, were found to follow power laws with an\nexponent close to $3$ in all samples. The observed proportionality between\n$1/T_{\\text{1}}$ and the polarization rate $1/T_{\\text{pol}}$, with a\ncoefficient related to the electron polarization, is consistent with the\npresence of Thermal Mixing (TM) and a good contact between the nuclear and the\nelectron spins. At high electron concentration additional relaxation channels\ncausing a decrease in the nuclear polarization must be considered. These\nresults provide further support for a more extensive use of amorphous DNP-ready\nsamples, obtained by means of comilling, in dissolution DNP experiments and\npossibly for $\\textit{in vivo}$ metabolic imaging.",
        "positive": "Highly asymmetric electrolytes in the primitive model: Hypernetted chain\n  solution in arbitrary spatial dimensions: The pair-correlation functions for fluid ionic mixtures in arbitrary spatial\ndimensions are computed in hypernetted chain (HNC) approximation. In the\nprimitive model, all ions are approximated as non-overlapping hyperspheres with\nCoulomb interactions. Our spectral HNC solver is based on a Fourier-Bessel\ntransform introduced by Talman [J. Comput. Phys., 29, 35 (1978)], with\nlogarithmically spaced computational grids. Numeric efficiency for arbitrary\nspatial dimensions is a commonly exploited virtue of this transform method.\nHere, we highlight another advantage of logarithmic grids, consisting in\nefficient sampling of pair-correlation functions for highly asymmetric ionic\nmixtures. For three-dimensional fluids, ion size- and charge-ratios larger than\none thousand can be treated, corresponding to hitherto computationally not\naccessed micrometer-sized colloidal spheres in 1-1 electrolyte. Effective\ncolloidal charge numbers are extracted from our primitive model results. For\nmoderately large ion size- and charge-asymmetries, we present Molecular\nDynamics simulation results that agree well with the approximate HNC pair\ncorrelations."
    },
    {
        "anchor": "Connecting thermodynamic and dynamical anomalies of water-like\n  liquid-liquid phase transition in the Fermi-Jagla model: We present a study using molecular dynamics simulations based on the\nFermi-Jagla potential model, which is the continuous version of the mono-atomic\ncore-softened Jagla model [J. Y. Abraham, S. V. Buldyrev, and N.\nGiovambattista, J. Phys. Chem. B, 115, 14229 (2011)]. This model shows the\nwater-like liquid-liquid phase transition between high-density and low-density\nliquids at the liquid-liquid critical point. In particular, the slope of the\ncoexistence line becomes weakly negative, which is expected to represent one of\nanomalies of liquid polyamorphism. In this study, we examined the density,\ndynamic, and thermodynamic anomalies in the vicinity of the liquid-liquid\ncritical point. The boundaries of density, self-diffusion, shear viscosity, and\nexcess entropy anomalies were characterized. Furthermore, these anomalies are\nconnected according to the Rosenfeld's scaling relationship between the excess\nentropy and the transport coefficients such as diffusion and viscosity. The\nresults demonstrate the hierarchical and nested structures regarding the\nthermodynamic and dynamic anomalies of the Fermi-Jagla model.",
        "positive": "Theoretical and numerical study of the phase diagram of patchy colloids:\n  ordered and disordered patch arrangements: We report theoretical and numerical evaluations of the phase diagram for a\nmodel of patchy particles. Specifically we study hard-spheres whose surface is\ndecorated by a small number f of identical sites (\"sticky spots'') interacting\nvia a short-range square-well attraction. We theoretically evaluate, solving\nthe Wertheim theory, the location of the critical point and the gas-liquid\ncoexistence line for several values of f and compare them to results of Gibbs\nand Grand Canonical Monte Carlo simulations. We study both ordered and\ndisordered arrangements of the sites on the hard-sphere surface and confirm\nthat patchiness has a strong effect on the phase diagram: the gas-liquid\ncoexistence region in the temperature-density plane is significantly reduced as\nf decreases. We also theoretically evaluate the locus of specific heat maxima\nand the percolation line."
    },
    {
        "anchor": "Morphology and kinetics of asphalt binder microstructure at gas, liquid,\n  and solid interfaces: We combined optical and atomic force microscopy to observe morphology and\nkinetics of microstructures that formed at free surfaces of unmodified\npavement-grade 64-22 asphalt binders upon cooling from 150 $^{\\circ}$C to room\ntemperature (RT) at 5 $^{\\circ}$C/min, and changes in these microstructures\nwhen the surface was terminated with a transparent solid (glass) or liquid\n(glycerol) over-layer. The main findings are: (1) At free binder surfaces,\nwrinkled microstructures started to form near the wax crystallization\ntemperature ($\\sim$45 $^{\\circ}$C), then grew to $\\sim$5 $\\mu$m diameter,\n$\\sim$25 nm wrinkle amplitude and 10-30$\\%$ surface area coverage upon cooling\nto RT, where they persisted indefinitely without observable change in shape or\ndensity. (2) Glycerol coverage of the binder surface during cooling reduced\nwrinkled area and wrinkle amplitude three-fold compared to free binder surfaces\nupon initial cooling to RT; continued glycerol coverage at RT eliminated most\nsurface microstructures within $\\sim$4 hours. (3) No surface microstructures\nwere observed to form at binder surfaces covered with glass. (4) Sub-micron\nbulk microstructures were observed by near-infrared microscopy beneath the\nsurfaces of all binder samples, with size, shape and density independent of\nsurface coverage. No tendency of such structures to float to the top or sink to\nthe bottom of mm-thick samples was observed. (5) We attribute the dependence of\nsurface wrinkling on surface coverage to variation in interface tension, based\non a thin-film continuum mechanics model.",
        "positive": "Structure of marginally jammed polydisperse packings of frictionless\n  spheres: We model the packing structure of a marginally jammed bulk ensemble of\npolydisperse spheres using an extended granocentric mode explicitly taking into\naccount rattlers. This leads to a relation- ship between the characteristic\nparameters of the packing, such as the mean number of neighbors and the\nfraction of rattlers, and the radial distribution function g(r). We find\nexcellent agreement between the model predictions for g(r) and packing\nsimulations as well as experiments on jammed emulsion droplets. The observed\nquantitative agreement opens the path towards a full structural\ncharacterization of jammed particle systems for imaging and scattering\nexperiments."
    },
    {
        "anchor": "Lift force acting on an intruder in dense, granular shear flows: We report a new lift force model for intruders in dense, granular shear\nflows. Our derivation is based on the thermal buoyancy model of Trujillo &\nHermann[L. Trujillo and H. J. Herrmann, Physica A 330, 519 (2003).], but takes\ninto account both granular temperature and pressure differences in the\nderivation of the net buoyancy force acting on the intruder. In a second step\nthe model is extended to take into account also density differences between the\nintruder and the bed particles. The model predicts very well the rising and\nsinking of intruders, the lift force acting on intruders as determined by\ndiscrete element model (DEM) simulations and the neutral-buoyancy limit of\nintruders in shear flows. Phenomenologically, we observe a cooling upon the\nintroduction of an intruder into the system. This cooling effect increases with\nintruder size and explains the sinking of large intruders. On the other hand,\nthe introduction of small to mid-sized intruders, i.e. up to 4 times the bed\nparticle size, leads to a reduction in the granular pressure compared to the\nhydrostatic pressure, which in turn causes the rising of small to mid-sized\nintruders.",
        "positive": "Wetting, Spreading, and Adsorption on Randomly Rough Surfaces: The wetting properties of solid substrates with customary (i.e., macroscopic)\nrandom roughness are considered as a function of the microscopic contact angle\nof the wetting liquid and its partial pressure in the surrounding gas phase.\nAnalytic expressions are derived which allow for any given lateral correlation\nfunction and height distribution of the roughness to calculate the wetting\nphase diagram, the adsorption isotherms, and to locate the percolation\ntransition in the adsorbed liquid film. Most features turn out to depend only\non a few key parameters of the roughness, which can be clearly identified. It\nis shown that a first order transition in the adsorbed film thickness, which we\nterm 'Wenzel prewetting', occurs generically on typical roughness topographies,\nbut is absent on purely Gaussian roughness. It is thereby shown that even\nsubtle deviations from Gaussian roughness characteristics may be essential for\ncorrectly predicting even qualitative aspects of wetting."
    },
    {
        "anchor": "Exploring particle dynamics in flowing complex fluids using differential\n  dynamic microscopy: Microscopic dynamics reveal the origin of the bulk rheological response in\ncomplex fluids. In model systems particle motion can be tracked, but for\nindustrially relevant samples this is often impossible. Here we adapt\ndifferential dynamic microscopy (DDM) to study flowing highly-concentrated\nsamples without particle resolution. By combining an investigation of\noscillatory flow, using a novel \"echo-DDM\" analysis, and steady shear, through\nflow-DDM, we characterise the yielding of a silicone oil emulsion on both the\nmicroscopic and bulk level. Through measuring the rate of shear-induced droplet\nrearrangements and the flow velocity, the transition from a solid-like to\nliquid-like state is shown to occur in two steps: with droplet mobilisation\nmarking the limit of linear visco-elasticity, followed by the development of\nshear localisation and macroscopic yielding. Using this suite of techniques,\nsuch insight could be developed for a wide variety of challenging complex\nfluids.",
        "positive": "Understanding the Low-Frequency Modes in Disordered Systems at\n  Single-Particle Level: Normal modes provide a fundamental basis for understanding crucial properties\nof solids, such as the thermal conductivity, the heat capacity and the sound\npropagation. While the normal modes are excellently described by plane waves in\ncrystals, they are far less understood in disordered systems, due to the great\ndifficulties in characterizing the heterogeneous vibrational behaviors. Using\ncharged colloids with long-range repulsion, we successfully make different\ndisordered systems without any contact friction, whose normal modes can be\nvisualized at single-particle level. In these systems, we directly tackle the\nlong-time outstanding puzzle in condensed matter physics: the microscopic\norigin of the low-frequency modes in disordered systems. For the first time, we\nexperimentally clarify that the low-frequency modes are caused by the\ncollective resonance of relatively disordered particles (or soft structures)\ncoupled with long-wavelength transverse excitations, settling this puzzle at\nsingle-particle level. Next to these low-frequency modes in the density of\nstates, we also observe a plateau due to isostaticity, verifying the\nfundamental prediction of jamming model. Moreover, we reveal the intrinsic\ncorrelation between the low-frequency modes and the real dynamics, which may\nlead to a universal mechanism for aging, melting and yielding."
    },
    {
        "anchor": "Rigidity of glasses and jamming systems at low temperatures: We discuss a microscopic scheme to compute the rigidity of glasses or the\nplateau modulus of supercooled liquids by twisting replicated liquids. We first\nsummarize the method in the case of harmonic glasses with analytic potentials.\nThen we discuss how it can be extended to the case of repulsive contact systems\n: the hard sphere glass and related systems with repulsive contact potentials\nwhich enable the jamming transition at zero temperature. For the repulsive\ncontact systems we find entropic rigidity which behaves similarly as the\npressure in the low temperature limit: it is proportional to the temperature\nand tends to diverge approaching the jamming density with increasing volume\nfraction, which may account for experimental observations of rigidities of\nrepulsive colloids and emulsions.",
        "positive": "Pathways connecting two opposed bilayers with a fusion pore: A\n  molecularly-informed phase field approach: A phase field model with two phase fields, representing the concentration and\nthe head-tail separation of amphiphilic molecules, respectively, has been\nconstructed using an extension of the Ohta-Kawasaki model (Macromolecules 19,\n2621-2632 (1986)). It is shown that this molecularly-informed phase field model\nis capable of producing various self-assembled amphiphilic aggregates, such as\nbilayers, vesicles and micelles. Furthermore, pathways connecting two opposed\nbilayers with a fusion pore are obtained by using a combination of the phase\nfield model and the string method. Multiple fusion pathways, including a\nclassical pathway and a leaky pathway, have been obtained depending on the\ninitial separation of the two bilayers. The study shed light to the\nunderstanding of membrane fusion pathways and, more importantly, laid a\nfoundation for further investigation of more complex membrane morphologies and\ntransitions."
    },
    {
        "anchor": "Actuation of cylindrical nematic elastomer balloons: Nematic elastomers are programmable soft materials that display large,\nreversible and predictable deformation under an external stimulus such as a\nchange in temperature or light. While much of the work in the field has focused\non actuation from flat sheets, recent advances in 3D printing and other methods\nof directed synthesis have motivated the study of actuation of curved shells.\nSnap-through buckling has been a topic of particular interest. In this work, we\npresent theoretical calculations to motivate another mode of actuation that\ncombines programmable soft materials as well as instabilities associated with\nlarge deformation. Specifically, we analyze the deformation of a cylindrical\nshell of a patterned nematic elastomer under pressure, show that it can undergo\nan enormous change of volume with changing temperature and suggest its\napplication as a pump with extremely high ejection fraction.",
        "positive": "Custom flow in overdamped Brownian Dynamics: When an external field drives a colloidal system out of equilibrium, the\nensuing colloidal response can be very complex and obtaining a detailed\nphysical understanding often requires case-by-case considerations. In order to\nfacilitate systematic analysis, here we present a general iterative scheme for\nthe determination of the unique external force field that yields a prescribed\ninhomogeneous stationary or time-dependent flow in an overdamped Brownian\nmany-body system. The computer simulation method is based on the exact one-body\nforce balance equation and allows to specifically tailor both gradient and\nrotational velocity contributions, as well as to freely control the one-body\ndensity distribution. Hence compressibility of the flow field can be fully\nadjusted. The practical convergence to a unique external force field\ndemonstrates the existence of a functional map from both velocity and density\nto external force field, as predicted by the power functional variational\nframework. In equilibrium, the method allows to find the conservative force\nfield that generates a prescribed target density profile, and hence implements\nthe Mermin-Evans classical density functional map from density distribution to\nexternal potential. The conceptual tools developed here enable one to gain\ndetailed physical insight into complex flow behaviour, as we demonstrate in\nprototypical situations."
    },
    {
        "anchor": "Static friction at fractal interfaces: Tribological phenomena are governed by combined effects of material\nproperties, topology and surface-chemistry. We study the interplay of\nmultiscale surface structures with molecular-scale interactions towards\ninterpreting static frictional interactions at fractal interfaces. By\nspline-assisted-discretization we analyse asperity interactions in pairs of\ncontacting fractal surface-profiles. For elastically deforming asperities,\nforce analysis reveals greater friction at surfaces exhibiting higher\nfractality, with increasing molecular-scale friction amplifying this trend.\nIncreasing adhesive strength yields higher overall friction at surfaces of\nlower fractality owing to greater true-contact-area. In systems where\nadhesive-type interactions play an important role, such as those where\ncold-welded junctions form, friction is minimised at an intermediate value of\nsurface profile fractality found to be around 1.3 to 1.5. Results have\nimplications for systems exhibiting evolving surface structures.",
        "positive": "The size of electron-hole pairs in pi conjugated systems: We have performed momentum dependent electron energy-loss studies of the\nelectronic excitations in sexithiophene and compared the results to those from\nparent oligomers. Our experiment probes the dynamic structure factor\nS(q,omega)and we show that the momentum dependent intensity variation of the\nexcitations observed can be used to extract the size of the electron-hole pair\ncreated in the excitation process. The extension of the electron-hole pairs\nalong the molecules is comparable to the length of the molecules and thus maybe\nonly limited by structural constraints. Consequently, the primary\nintramolecular electron-hole pairs are relatively weakly bound. We find no\nevidence for the formation of excitations localized on single thiophene units."
    },
    {
        "anchor": "Potential Energy Landscape Equation of State: Depth, number, and shape of the basins of the potential energy landscape are\nthe key ingredients of the inherent structure thermodynamic formalism\nintroduced by Stillinger and Weber [F. H. Stillinger and T. A. Weber, Phys.\nRev. A 25, 978 (1982)]. Within this formalism, an equation of state based only\non the volume dependence of these landscape properties is derived. Vibrational\nand configurational contributions to pressure are sorted out in a transparent\nway. Predictions are successfully compared with data from extensive molecular\ndynamics simulations of a simple model for the fragile liquid orthoterphenyl.",
        "positive": "Low-frequency vibrations of soft colloidal glasses: We conduct experiments on two-dimensional packings of colloidal\nthermosensitive hydrogel particles whose packing fraction can be tuned above\nthe jamming transition by varying the temperature. By measuring displacement\ncorrelations between particles, we extract the vibrational properties of a\ncorresponding \"shadow\" system with the same configuration and interactions, but\nfor which the dynamics of the particles are undamped. The vibrational spectrum\nand the nature of the modes are very similar to those predicted for\nzero-temperature idealized sphere models and found in atomic and molecular\nglasses; there is a boson peak at low frequency that shifts to higher frequency\nas the system is compressed above the jamming transition."
    },
    {
        "anchor": "A statistical theory of coil-to-globule-to-coil transition of a polymer\n  chain in the mixture of good solvents: We present an off-lattice statistical model of a single polymer chain in\nmixed solvent media. Taking into account a polymer conformational entropy,\nrenormalization of solvent composition near the polymer backbone, the universal\nintermolecular excluded volume and Van-der-Waals interactions within the\nself-consistent field theory the reentrant coil-to-globule-to-coil transition\n(co-nonsolvency) has been described in this paper. For convenience we split the\nsystem volume in two parts: the volume occupied by the polymer chain and the\nvolume of bulk solution. Considering the equilibrium between two sub-volumes,\nthe polymer solvation free energy as a function of radius of gyration and\nco-solvent mole fraction within internal polymer volume has been obtained.\nMinimizing the free energy of solvation with respect to its arguments, we show\ntwo qulitatively different regimes of co-nonsolvency. Namely, at sufficiently\nhigh temperature a reentrant coil-to-globule-to-coil transition proceeds\nsmoothly. On the contrary, when the temperature drops below a certain threshold\nvalue a coil-globule transition occurs in the regime of first-order phase\ntransition, i.e., discontinuous changes of the radius of gyration and the local\nco-solvent mole fraction near the polymer backbone. We show that, when the\ncollapse of polymer chain takes place, the entropy and enthalpy contributions\nto the solvation free energy of globule strongly grow. From the first\nprinciples of statistical thermodynamics we confirm earlier speculations based\non the MD simulations results that the co-nonsolvency is the essentially\nenthalpic-entropic effect and caused by enthalpy-entropy compensation. We show\nthat the temperature dependences of solution heat capacity change due to the\nsolvation of polymer chain are in qualitative agreement with the Differential\nscanning calorimetry data for PNIPAM in aqueous methanol.",
        "positive": "Using low dose X-ray Speckle Visibility Spectroscopy to study dynamics\n  of soft matter samples: We demonstrate the successful application of X-ray Speckle Visibility\nSpectroscopy (XSVS) experiments to study the dynamics of radiation sensitive,\nbiological samples with unprecedentedly small X-ray doses of 45 Gy and below.\nUsing XSVS, we track the dynamics of casein micelles in native, concentrated,\nand acidified solution conditions, while substantially reducing the deposited\ndose as compared to alternative techniques like sequential X-ray photon\ncorrelation spectroscopy (XPCS). The Brownian motion in a skim milk sample\nyields the hydrodynamic radius of the casein micelles while deviations from\nBrownian motion with a characteristic $q$-dependent diffusion coefficient\n$D(q)$ can be observed in more concentrated solution conditions. The low dose\napplied in our experiments allows the observation of static, frozen speckle\npatterns from gelled acidic milk. We show that the XSVS technique is especially\nsuitable for tracking dynamics of radiation sensitive samples in combination\nwith the improved coherent properties of new generation X-ray sources,\nemphasizing the great potential for further investigations of protein dynamics\nusing fourth generation synchrotrons and free electron lasers."
    },
    {
        "anchor": "Dilatational-Plasticity Opens a New Mechanistic Pathway for\n  Macromolecular Transport Across Polymeric Interfaces Yielding Solid-State\n  Bonding: Bonding between polymeric interfaces is encountered widely in several\nindustrial applications. Many of these bonding processes rely on time-consuming\nand temperature-dependent classical mechanism of polymer interdiffusion via\nreptation in a melt state. Here, for the first time, we report a new\nmechanistic pathway for achieving solid-state polymer bonding by triggering\nrapid macromolecular acceleration through mechanical deformation. Large-scale\nmolecular simulations reveal that active plastic deformation in glassy\npolymers, at temperatures well-below the bulk (and surface) glass transition\ntemperatures, is sufficient to cause segmental translations of the polymer\nchains that lead to interfacial interpenetrations, and formation of new\nentanglements. The underlying mechanistic basis for this new type of bonding is\nidentified as enhanced molecular-scale dilatations (or densifications) in\nconjunction with accelerated molecular mobility during plastic deformation. The\nreported mechanistic insights open promising avenues for designing new bonding\ntechnologies or material systems, and transformation of the existing ones to\nachieve quick and energetically less intensive bonding.",
        "positive": "Elastic moduli of a smectic membrane: a rod-level scaling analysis: Chiral rodlike colloids exposed to strong depletion attraction may\nself-assemble into chiral membranes whose twisted director field differs from\nthat of a 3D bulk chiral nematic. We formulate a simple microscopic variational\ntheory to determine the elastic moduli of rods assembled into a bi-dimensional\nsmectic membrane. The approach is based on a simple Onsager-Straley theory for\na non-uniform director field that we apply to describe rod twist within the\nmembrane. A microscopic approach enables a detailed estimate of the individual\nFrank elastic moduli (splay, twist and bend) as well as the twist penetration\ndepth of the smectic membrane in relation to the rod density and shape. We find\nthat the elastic moduli are distinctly different from those of a bulk nematic\nfluid, with the splay elasticity being much larger and the curvature elasticity\nmuch smaller than for rods assembled in a three-dimensional nematic fluid. We\nargue that the use of the simplistic one-constant approximation in which all\nmoduli are assumed to be of equal magnitude is not appropriate for modelling\nthe structure-property relation of smectic membranes."
    },
    {
        "anchor": "Experimental Evidence for Algebraic Double-Layer Forces: According to conventional wisdom electric double-layer forces normally decay\nexponentially with separation distance. Here we present experimental evidence\nof algebraically decaying double-layer interactions. We show that algebraic\ninteractions arise in both strongly overlapping as well as counterion-only\nregimes, albeit the evidence is less clear for the former regime. In both of\nthese cases the disjoining pressure profile assumes an inverse square distance\ndependence. At small separation distances another algebraic regime is\nrecovered. In this regime the pressure decays as the inverse of separation\ndistance.",
        "positive": "Do ferroelectric nematic liquid crystals really have a huge dielectric\n  permittivity?: There is much scientific debate as to whether the newly discovered\nferroelectric nematic liquid crystals actually have a huge relative dielectric\nconstant or whether it is just an artefact related to the interpretation of the\ndielectric spectroscopy measurement results. We show that the interpretation of\nthe dielectric measurements of highly polar liquid crystalline material\nrequires a new model that takes into account both the frequency response of the\ntested material and the capacitance of the thin surface layers. A proper\ninterpretation of the measurements confirms a huge relative permittivity of the\nferroelectric nematic phase, which can even be orders of magnitude larger than\nthe measured apparent values. Furthermore, the value is independent of the cell\nthickness and the type of surface electrodes."
    },
    {
        "anchor": "A novel general modeling of the viscoelastic properties of fluids:\n  application to mechanical relaxation and low frequency oscillation\n  measurements of liquid water: The aim of this paper is to calculate the time dependence of the mean\nposition (and orientation) of a fluid particle when a fluid system at\nthermodynamic equilibrium is submitted to a mechanical action. The starting\npoint of this novel theoretical approach is the introduction of a mechanical\nenergy functional. Then using the notions of inertial modes and action\ntemperature, and assuming a mechanical energy equipartition principle per mode,\nthe model predict the existence of a dynamic phase transition where the\nrheological behavior of the medium evolves from a solid-like to a liquid-like\nregime when the mechanical action is increased. The well-known Newtonian\nbehavior is recovered as limiting case. The present modeling is applied to the\nanalysis of recent liquid water viscoelastic data pointing out a prevalent\nelastic behavior in confined geometry. It is demonstrated that the model makes\nit possible to understand these data in a coherent and unified way with the\ntransport properties (viscosity and self-diffusion coefficient). It is\nconcluded that any finite volume of fluid at rest possesses a static shear\nelasticity and should therefore be considered as a solid-like medium.",
        "positive": "Fractal-Mound Growth of Pentacene Thin Films: The growth mechanism of pentacene film formation on SiO2 substrate was\ninvestigated with a combination of atomic force microscopy measurements and\nnumerical modeling. In addition to the diffusion-limited aggregation (DLA) that\nhas already been shown to govern the growth of the ordered pentacene thin\nfilms, it is shown here for the first time that the Schwoebel barrier effect\nsteps in and disrupts the desired epitaxial growth for the subsequent layers,\nleading to mound growth. The terraces of the growing mounds have a fractal\ndimension of 1.6, indicating a lateral DLA shape. This novel growth morphology\nthus combines horizontal DLA-like growth with vertical mound growth."
    },
    {
        "anchor": "Implementation of Lees-Edwards periodic boundary conditions for direct\n  numerical simulations of particle dispersions under shear flow: A general methodology is presented to perform direct numerical simulations of\nparticle dispersions in a shear flow with Lees-Edwards periodic boundary\nconditions. The Navier-Stokes equation is solved in oblique coordinates to\nresolve the incompatibility of the fluid motions with the sheared geometry, and\nthe force coupling between colloidal particles and the host fluid is imposed by\nusing a smoothed profile method. The validity of the method is carefully\nexamined by comparing the present numerical results with experimental viscosity\ndata for particle dispersions in a wide range of volume fractions and shear\nrates including nonlinear shear-thinning regimes.",
        "positive": "Entropic patchiness drives multi-phase coexistence in discotic\n  colloid-depletant mixtures: Entropy-driven equilibrium phase behaviour of hard particle dispersions can\nbe understood from excluded volume arguments only. While monodisperse hard\nspheres only exhibit a fluid-solid phase transition, anisotropic hard particles\nsuch as rods, discs, cuboids or boards exhibit various multi-phase equilibria.\nOrdering of such anisotropic particles increases the free volume entropy by\nreducing the excluded volume between them. The addition of depletants gives\nrise to an entropic patchiness represented by orientation-dependent attraction\nresulting in non-trivial phase behaviour. We show that free volume theory is a\nsimple, generic and tractable framework that enables to incorporate these\neffects and rationalise various experimental findings. Plate-shaped particles\nconstitute the main building blocks of clays, asphaltenes and chromonic liquid\ncrystals that find widespread use in the food, cosmetics and oil industry. We\ndemonstrate that mixtures of platelets and ideal depletants exhibit a\nstrikingly rich phase behaviour containing several types of three-phase\ncoexistence areas and even a quadruple region with four coexisting phases."
    },
    {
        "anchor": "Hydrodynamic theory of flocking at a solid-liquid interface: long range\n  order and giant number fluctuations: We construct the hydrodynamic theory of coherent collective motion\n(\"flocking\") at a solid-liquid interface. The polar order parameter and\nconcentration of a collection of \"active\" (self-propelled) particles at a\nplanar interface between a passive, isotropic bulk fluid and a solid surface\nare dynamically coupled to the bulk fluid. We find that such systems are\nstable, and have long-range orientational order, over a wide range of\nparameters. When stable, these systems exhibit \"giant number fluctuations\",\ni.e., large fluctuations of the number of active particles in a fixed large\narea. Specifically, these number fluctuations grow as the $3/4$th power of the\nmean number within the area. Stable systems also exhibit anomalously rapid\ndiffusion of tagged particles suspended in the passive fluid along any\ndirections in a plane parallel to the solid-liquid interface, whereas the\ndiffusivity along the direction perpendicular to the plane is non-anomalous. In\nother parameter regimes, the system becomes unstable.",
        "positive": "Hierarchical modeling of polystyrene melts: From soft blobs to atomistic\n  resolution: We demonstrate that hierarchical backmapping strategies incorporating generic\nblob-based models can equilibrate melts of high-molecular-weight polymers,\ndescribed with chemically specific, atomistic, models. The central idea behind\nthese strategies, is first to represent polymers by chains of large soft blobs\n(spheres) and efficiently equilibrate the melt on mesoscopic scale. Then, the\ndegrees of freedom of more detailed models are reinserted step by step. The\nprocedure terminates when the atomistic description is reached. Reinsertions\nare feasible computationally because the fine-grained melt must be\nre-equilibrated only locally. To develop the method, we choose a polymer with\nsufficient complexity. We consider polystyrene (PS), characterized by\nstereochemistry and bulky side groups. Our backmapping strategy bridges\nmesoscopic and atomistic scales by incorporating a blob-based, a moderately CG,\nand a united-atom model of PS. We demonstrate that the generic blob-based model\ncan be parameterized to reproduce the mesoscale properties of a specific\npolymer -- here PS. The moderately CG model captures stereochemistry. To\nperform backmapping we improve and adjust several fine-graining techniques. We\nprove equilibration of backmapped PS melts by comparing their structural and\nconformational properties with reference data from smaller systems,\nequilibrated with less efficient methods."
    },
    {
        "anchor": "Hamiltonian and Potentials in Derivative Pricing Models: Exact Results\n  and Lattice Simulations: The pricing of options, warrants and other derivative securities is one of\nthe great success of financial economics. These financial products can be\nmodeled and simulated using quantum mechanical instruments based on a\nHamiltonian formulation. We show here some applications of these methods for\nvarious potentials, which we have simulated via lattice Langevin and Monte\nCarlo algorithms, to the pricing of options. We focus on barrier or path\ndependent options, showing in some detail the computational strategies\ninvolved.",
        "positive": "Vorticity, Defects and Correlations in Active Turbulence: We describe a numerical investigation of a continuum model of an active\nnematic, concentrating on the regime of active turbulence. Results are\npresented for the effect of three parameters, activity, elastic constant and\nrotational diffusion constant, on the order parameter and flow fields. Defects\nand distortions in the director field act as sources of vorticity, and thus\nvorticity is strongly correlated to the director field. In particular the\ncharacteristic length of decay of vorticity and order parameter correlations is\ncontrolled by the defect density. By contrast the decay of velocity\ncorrelations is determined by a balance between activity and dissipation. We\nhighlight the role of microscopic flow generation mechanisms in determining the\nflow patterns and characteristic scales of active turbulence and contrast the\nbehaviour of extensile and contractile active nematics."
    },
    {
        "anchor": "Stability and folds in an elastocapillary system: We examine the equilibrium and stability of an elastocapillary system to\nmodel drying-induced structural failures. The model comprises a circular\nelastic membrane with a hole at the center that is deformed by the capillary\npressure of simply connected and doubly connected menisci. Using variational\nand spectral methods, stability is related to the slope of equilibrium branches\nin the liquid content versus pressure diagram for the constrained and\nunconstrained problems. The second-variation spectra are separately determined\nfor the membrane and meniscus, showing that the membrane out-of-plane spectrum\nand the in-plane spectrum at large elatocapillary numbers are both positive, so\nthat only meniscus perturbations can cause instability. At small\nelastocapillary numbers, the in-plane spectrum has a negative eigenvalue,\ninducing wrinkling instabilities in thin membranes. In contrast, the smallest\neigenvalue of the meniscus spectrum always changes sign at a pressure turning\npoint where stability exchange occurs in the unconstrained problem. We also\nexamine configurations in which the meniscus and membrane are individually\nstable, while the elastocapillary system as a whole is not; this emphasizes the\nconnection between stability and the coupling of elastic and capillary forces.",
        "positive": "Miscibility Phase Diagram of Ring Polymer Blends: A Topological Effect: The miscibility of polymer blends, a classical problem in polymer science,\nmay be altered, if one or both of the component do not have chain ends. Based\non the idea of {\\it topological volume}, we propose a mean-field theory to\nclarify how the topological constraints in ring polymers affect the phase\nbehavior of the blends. While the large enhancement of the miscibility is\nexpected for ring-linear polymer blends, the opposite trend toward demixing,\nalbeit comparatively weak, is predicted for ring-ring polymer blends. Scaling\nformulas for the shift of critical point for both cases are derived. We discuss\nthe valid range of the present theory, and the crossover to the linear polymer\nblends behaviors, which is expected for short chains. These analysis put\nforward a view that the topological constraints could be represented as an\neffective excluded-volume effects, in which the topological length plays a role\nof the screening factor."
    },
    {
        "anchor": "Insight into properties of sizable glass former from volumetric\n  measurements: Sizable glass formers feature numerous unique properties and potential\napplications, but many questions regarding their glass transition dynamics have\nnot been resolved yet. Here we analyzed structural relaxation times measured as\na function of temperature and pressure in combination with the equation of\nstate obtained from pressure-volume-temperature (PVT) measurements. Despite\nevidence from previous dielectric studies indicating a remarkable sensitivity\nof supercooled dynamics to compression, and contrary to intuition, our results\ndemonstrated the temperate proof for the almost equivalent importance of\nthermal energy and free volume fluctuations in controlling reorientation\ndynamics of sizable molecules. The found scaling exponent equals 3.0 and Ev/Ep\nratio of 0.6 were typical for glass-forming materials with relaxation dynamics\ndetermined by both effects with a minor advantage of thermal fluctuations\ninvolvement. It shows that the high values of key parameters characterizing the\nsensitivity of the glass transition dynamics to pressure changes, i.e.\nactivation volume and dTg/dP, are not a valid premise for a remarkable\ncontribution of volume on glass transition dynamics.",
        "positive": "Influence of elastic deformation of porous materials in\n  adsorption-desorption process. A thermodynamic approach: It has been known for a long time that the adsorption and condensation of gas\ncause elastic deformation of the porous matrix. The reversible formation of an\nadsorbed film, which precedes capillary condensation, results in an extension\nof the porous material while, in the hysteresis region, the negative liquid\npressures under the concave menisci contract the porous matrix. The elastic\ndeformation exhibits an hysteresis loop in the same pressure region as the\nadsorption phenomenon. These deformations have been neglected in practically\nall the theoretical treatments of adsorption. We develop a thermodynamic\napproach which includes the elastic energy of the solid. This approach is\ngeneric to all porous materials. Thermodynamics of adsorption is directly\nconnected to the elastic properties of the porous solid. We find that the\nvariation of the surface free energy related to the elastic deformation is an\nimportant component of the total free energy. It is shown that the condensation\nbranch represents the more stable states and that an energy barrier exists to\nevaporation which depends essentially on the elastic deformation. The pores\ninteract through the deformation of the walls. Based on this interaction\nmechanism and on the shape of the scanning curves which are common to materials\nwith interconnected pores such as porous glass or noninterconnected pores such\nas p+-type porous silicon and SBA-15, we propose a scenario for the filling and\nemptying of these porous materials."
    },
    {
        "anchor": "Size Scaling of Neutral Polymers and Charged Polymers in Nanochannels: We expand the blob theory for freely-jointed chains and perform molecular\ndynamics simulations to study the behavior of polymers confined in cylindrical\nchannels. From weak to strong confinement, five scaling regimes, de Gennes,\nextended de Gennes, transition, backfolding, and Odijk regimes, are\ndistinguished for neutral polymers.The size scalings in each regime are derived\nas a function of the channel width. The scaling exponents $-1$ and $-1/3$ are\nobtained for the transition and backfolding regimes, respectively, which result\nfrom the reduction of the excluded volume of the segments by restriction of the\nsegment's orientation in the narrowed channels. For charged flexible chains,\nthe de Gennes regime is split into Flory-de Gennes and electro-de Gennes\nregimes owing to strong Coulomb repulsion in electrostatic blobs. Nonetheless,\nthe extended de Gennes and transition regimes are shrunken. The study of the\nfluctuations of the chain size shows consistent scaling demarcations for both\nthe neutral and charged chain systems.",
        "positive": "Applications of the kinetic theory for a model of a confined quasi-two\n  dimensional granular mixture: Stability analysis and thermal diffusion\n  segregation: The Boltzmann kinetic theory for a model of a confined quasi-two dimensional\ngranular mixture derived previously [Garz\\'o, Brito and Soto, Phys. Fluids\n\\textbf{33}, 023310 (2021)] is considered further to analyze two different\nproblems. First, a linear stability analysis of the hydrodynamic equations with\nrespect to the homogeneous steady state (HSS) is carried out to identify the\nconditions for stability as functions of the wave vector, the coefficients of\nrestitution, and the parameters of the mixture. The analysis, which is based on\nthe results obtained by solving the Boltzmann equation by means of the\nChapman--Enskog method to first order in spatial gradients, takes into account\nthe (nonlinear) dependence of the transport coefficients and the cooling rate\non the coefficients of restitution and applies in principle to arbitrary values\nof the concentration, and the mass and diameter ratios. In contrast to the\nresults obtained in the conventional inelastic hard sphere (IHS) model, the\nresults show that all the hydrodynamic modes are stable so that, the HSS is\nlinearly \\emph{stable} with respect to long enough wavelength excitations. As a\nsecond application, segregation induced by both a thermal gradient and gravity\nis studied. A segregation criterion based on the dependence of the thermal\ndiffusion factor $\\Lambda$ on the parameter space of the mixture is derived.\nComparison with previous results derived from the IHS model is carried out."
    },
    {
        "anchor": "Generation of Sound Bullets with a Nonlinear Acoustic Lens: Acoustic lenses are employed in a variety of applications, from biomedical\nimaging and surgery, to defense systems, but their performance is limited by\ntheir linear operational envelope and complexity. Here we show a dramatic\nfocusing effect and the generation of large amplitude, compact acoustic pulses\n(sound bullets) in solid and fluid media, enabled by a tunable, highly\nnonlinear acoustic lens. The lens consists of ordered arrays of granular\nchains. The amplitude, size and location of the sound bullets can be controlled\nby varying static pre-compression on the chains. We support our findings with\ntheory, numerical simulations, and corroborate the results experimentally with\nphotoelasticity measurements. Our nonlinear lens makes possible a qualitatively\nnew way of generating high-energy acoustic pulses, enabling, for example,\nsurgical control of acoustic energy.",
        "positive": "The effect of undulations on Spontaneous Braid formation: This paper extends on a recent work where it was shown that forces dependent\non the helical structure may cause two DNA molecules to spontaneously braid [R.\nCortini et Al, Biophys. J. 101, 875 (2011)]. Here, bending fluctuations of DNA\ncentre lines about the braid axis are incorporated into the braiding theory.\nThe free energy of the pair of molecules is recalculated and compared to its\nvalue without incorporating undulations. We find that the loss of\nconfigurational entropy due to confinement of the molecules in the braid is\nrather high. This contribution to the Free Energy pushes up the amount of\nattraction needed for spontaneous braiding due to helix dependant forces. The\ntheory will be further developed for plectonemes and braids under mechanical\nforces, in later work."
    },
    {
        "anchor": "Crazing of Nanocomposites with Polymer-Tethered Nanoparticles: The crazing behavior of polymer nanocomposites formed by blending polymer\ngrafted nanoparticles with an entangled polymer melt is studied by molecular\ndynamics simulations. We focus on the three key differences in the crazing\nbehavior of a composite relative to the pure homopolymer matrix, namely, a\nlower yield stress, a smaller extension ratio and a grafted chain length\ndependent failure stress. The yield behavior is found to be mostly controlled\nby the local nanoparticle-grafted polymer interfacial energy, with the grafted\npolymer-polymer matrix interfacial structure being of little to no relevance.\nIncreasing the attraction between nanoparticle core and the grafted polymer\ninhibits void nucleation and leads to a higher yield stress. In the craze\ngrowth regime, the presence of grafted chain sections of 100 monomers alters\nthe mechanical response of composite samples, giving rise to smaller extension\nratios and higher drawing stresses than for the homopolymer matrix. The\ndominant failure mechanism of composite samples depends strongly on the length\nof the grafted chains, with disentanglement being the dominant mechanism for\nshort chains, while bond breaking is the failure mode for chain lengths greater\nthan 10Ne, where Ne is the entanglement length.",
        "positive": "Algorithmic Lattice Kirigami: A Route to Pluripotent Materials: We use a regular arrangement of kirigami elements to demonstrate an inverse\ndesign paradigm for folding a flat surface into complex target configurations.\nWe first present a scheme using arrays of disclination defect pairs on the dual\nto the honeycomb lattice; by arranging these defect pairs properly with respect\nto each other and choosing an appropriate fold pattern a target stepped surface\ncan be designed. We then present a more general method that specifies a fixed\nlattice of kirigami cuts to be performed on a flat sheet. This single\n\"pluripotent\" lattice of cuts permits a wide variety of target surfaces to be\nprogrammed into the sheet by changing the folding directions."
    },
    {
        "anchor": "Video Microscopy of Colloidal Suspensions and Colloidal Crystals: Colloidal suspensions are simple model systems for the study of phase\ntransitions. Video microscopy is capable of directly imaging the structure and\ndynamics of colloidal suspensions in different phases. Recent results related\nto crystallization, glasses, and 2D systems complement and extend previous\ntheoretical and experimental studies. Moreover, new techniques allow the\ndetails of interactions between individual colloidal particles to be carefully\nmeasured. Understanding these details will be crucial for designing novel\ncolloidal phases and new materials, and for manipulating colloidal suspensions\nfor industrial uses.",
        "positive": "An Experimental Investigation of the Scaling of Columnar Joints: Columnar jointing is a fracture pattern common in igneous rocks in which\ncracks self-organize into a roughly hexagonal arrangement, leaving behind an\nordered colonnade. We report observations of columnar jointing in a laboratory\nanalog system, desiccated corn starch slurries. Using measurements of moisture\ndensity, evaporation rates, and fracture advance rates as evidence, we suggest\nan advective-diffusive system is responsible for the rough scaling behavior of\ncolumnar joints. This theory explains the order of magnitude difference in\nscales between jointing in lavas and in starches. We investigated the scaling\nof average columnar cross-sectional areas due to the evaporation rate, the\nanalog of the cooling rate of igneous columnar joints. We measured column areas\nin experiments where the evaporation rate depended on lamp height and time, in\nexperiments where the evaporation rate was fixed using feedback methods, and in\nexperiments where gelatin was added to vary the rheology of the starch. Our\nresults suggest that the column area at a particular depth is related to both\nthe current conditions, and hysteretically to the geometry of the pattern at\nprevious depths. We argue that there exists a range of stable column scales\nallowed for any particular evaporation rate."
    },
    {
        "anchor": "Subdiffusive axial transport of granular materials in a long drum mixer: Granular mixtures rapidly segregate radially by size when tumbled in a\npartially filled horizontal drum. The smaller component moves toward the axis\nof rotation and forms a buried core, which then splits into axial bands. Models\nhave generally assumed that the axial segregation is opposed by diffusion.\nUsing narrow pulses of the smaller component as initial conditions, we have\ncharacterized axial transport in the core. We find that the axial advance of\nthe segregated core is well described by a self-similar concentration profile\nwhose width scales as $t^\\alpha$, with $\\alpha \\sim 0.3 < 1/2$. Thus, the\nprocess is subdiffusive rather than diffusive as previously assumed. We find\nthat $\\alpha$ is nearly independent of the grain type and drum rotation rate\nwithin the smoothly streaming regime. We compare our results to two\none-dimensional PDE models which contain self-similarity and subdiffusion; a\nlinear fractional diffusion model and the nonlinear porous medium equation.",
        "positive": "Consequence of superfluidity on the expansion of a rotating\n  Bose-Einstein condensate: We study the time evolution of a rotating condensate, that expands after\nbeing suddenly released from the confining trap, by solving the hydrodynamic\nequations of irrotational superfluids. For slow initial rotation speeds,\n$\\Omega_{0}$, we find that the condensate's angular velocity increases rapidly\nto a maximum value and this is accompanied by a minimum in the deformation of\nthe condensate in the rotating plane. During the expansion the sample makes a\nglobal rotation of approximately $\\pi/2$, where the exact value depends on\n$\\Omega_{0}$. This minimum deformation can serve as an easily detectable\nsignature of superfluidity in a Bose--Einstein condensate."
    },
    {
        "anchor": "Explicit Analytical Solution for Random Close Packing in d=2 and d=3: We present an analytical derivation of the volume fractions for random close\npacking (RCP) in both $d=3$ and $d=2$, based on the same methodology. Using\nsuitably modified nearest neigbhour statistics for hard spheres, we obtain\n$\\phi_{\\mathrm{RCP}}=0.65896$ in $d=3$ and $\\phi_{\\mathrm{RCP}}=0.88648$ in\n$d=2$. These values are well within the interval of values reported in the\nliterature using different methods (experiments and numerical simulations) and\nprotocols. This order-agnostic derivation suggests some considerations related\nto the nature of RCP: (i) RCP corresponds to the onset of mechanical rigidity\nwhere the finite shear modulus emerges, (ii) the onset of mechanical rigidity\nmarks the maximally random jammmed state and dictates $\\phi_{\\mathrm{RCP}}$ via\nthe coordination number $z$, (iii) disordered packings with\n$\\phi>\\phi_{\\mathrm{RCP}}$ are possible at the expense of creating some order,\nand $z=12$ at the FCC limit acts as a boundary condition.",
        "positive": "Boundary-induced bulk phase transition and violation of Fick's law in\n  two-component single-file diffusion with open boundaries: We study two-component single-file diffusion inside a narrow channel that at\nits ends is open and connected with particle reservoirs. Using a two-species\nversion of the symmetric simple exclusion process as a model, we propose a\nhydrodynamic description of the coarse-grained dynamics with a self-diffusion\ncoefficient that is inversely proportional to the length of the channel. The\ntheory predicts an unexpected nonequilibrium phase transition for the bulk\nparticle density as the external total density gradient between the reservoirs\nis varied. The individual particle currents do not in general satisfy Fick's\nfirst law. These results are confirmed by extensive dynamical Monte-Carlo\nsimulations for equal diffusivities of the two components."
    },
    {
        "anchor": "Methods to Compute Pressure and Wall Tension in Fluids containing Hard\n  Particles: Colloidal systems are often modelled as fluids of hard particles (possibly\nwith an additional soft attraction, e.g. caused by polymers also contained in\nthe suspension). in simulations of such systems, the virial theorem cannot be\nstraightforwardly applied to obtain the components of the pressure tensor. In\nsystems confined by walls, it is hence also not straightforward to extract the\nexcess energy due to the wall (the \"wall tension\") from the pressure tensor\nanisotropy. A comparative evaluation of several methods to circumvent this\nproblem is presented, using as examples fluids of hard spheres and the\nAsakura-Oosawa model of colloid-polymer mixtures with a size ratio $q=0.15$\n(for which the effect of the polymers can be integrated out to yield an\neffective attractive potential between the colloids). Factors limiting the\naccuracy of the various methods are carefully discussed, and controlling these\nfactors very good mutual agreement between the various methods is found.",
        "positive": "Structural and Thermodynamic Properties of Hard-Sphere Fluids: This Perspective article provides an overview of some of our analytical\napproaches to the computation of the structural and thermodynamic properties of\nsingle-component and multicomponent hard-sphere fluids. For the structural\nproperties, they yield a thermodynamically consistent formulation, thus\nimproving and extending the known analytical results of the Percus--Yevick\ntheory. Approximate expressions linking the equation of state of the\nsingle-component fluid to the one of the multicomponent mixture are also\ndiscussed."
    },
    {
        "anchor": "Rotational Dynamics of Vortices in Confined Bose-Einstein Condensates: We derive the frequency of precession and conditions for stability for a\nquantized vortex in a single-component and a two-component Bose-Einstein\ncondensate. The frequency of precession is proportional to the gradient of the\nfree energy with respect to displacement of the vortex core. In a two-component\nsystem, it is possible to achieve a local minimum in the free energy at the\ncenter of the trap. The presence of such a minimum implies the existence of a\nregion of energetic stability where the vortex cannot escape and where one may\nbe able to generate a persistent current.",
        "positive": "Accelerated boundary integral method for multiphase flow in non-periodic\n  geometries: An accelerated boundary integral method for Stokes flow of a suspension of\ndeformable particles is presented for an arbitrary domain and implemented for\nthe important case of a planar slit geometry. The computational complexity of\nthe algorithm scales as O(N) or $O(N\\log N$), where $N$ is proportional to the\nproduct of number of particles and the number of elements employed to\ndiscretize the particle. This technique is enabled by the use of an alternative\nboundary integral formulation in which the velocity field is expressed in terms\nof a single layer integral alone, even in problems with non-matched\nviscosities. The density of the single layer integral is obtained from a\nFredholm integral equation of the second kind involving the double layer\nintegral. Acceleration in this implementation is provided by the use of General\nGeometry Ewald-like method (GGEM) for computing the velocity and stress fields\ndriven by a set of point forces in the geometry of interest. For the particular\ncase of the slit geometry, a Fourier-Chebyshev spectral discretization of GGEM\nis developed. Efficient implementations employing the GGEM methodology are\npresented for the resulting single and the double layer integrals. The\nimplementation is validated with test problems on the velocity of rigid\nparticles and drops between parallel walls in pressure driven flow, the Taylor\ndeformation parameter of capsules in simple shear flow and the particle\ntrajectory in pair collisions of capsules in shear flow. The computational\ncomplexity of the algorithm is verified with results from several large scale\nmultiparticle simulations."
    },
    {
        "anchor": "Molecular mechanism of the Debye relaxation in monohydroxy alcohols\n  revealed from rheo-dielectric spectroscopy: Rheodielectric spectroscopy is employed, for the first time, to investigate\nthe effect of external shear on the Debyelike relaxation of a model monohydroxy\nalcohol, i.e., the 2-ethyl-1-hexanol (2E1H). Shear deformation leads to strong\nacceleration in the structural relaxation, the Debye relaxation, and the\nterminal relaxation of 2E1H. Moreover, the shear-induced reduction in\nstructural relaxation time, tau_alpha, scales quadratically with that of Debye\ntime, tau_D, and the terminal flow time, tau_f, suggesting a relationship of\ntau_D*tau_D~tau_alpha. Further analyses reveal tau_D*tau_D/tau_alpha of 2E1H\nfollows Arrhenius temperature dependence that applies remarkably well to many\nother monohydroxy alcohols with different molecular sizes, architectures, and\nalcohol types. These results cannot be understood by the prevailing transient\nchain model and suggest a H-bonding breakage facilitated sub-supramolecular\nreorientation as the origin of Debye relaxation of monohydroxy alcohols, akin\nto the molecular mechanism for the terminal relaxation of unentangled living\npolymers",
        "positive": "Accelerating Copolymer Inverse Design using AI Gaming algorithm: There exists a broad class of sequencing problems, for example, in proteins\nand polymers that can be formulated as a heuristic search algorithm that\ninvolve decision making akin to a computer game. AI gaming algorithms such as\nMonte Carlo tree search (MCTS) gained prominence after their exemplary\nperformance in the computer Go game and are decision trees aimed at identifying\nthe path (moves) that should be taken by the policy to reach the final winning\nor optimal solution. Major challenges in inverse sequencing problems are that\nthe materials search space is extremely vast and property evaluation for each\nsequence is computationally demanding. Reaching an optimal solution by\nminimizing the total number of evaluations in a given design cycle is therefore\nhighly desirable. We demonstrate that one can adopt this approach for solving\nthe sequencing problem by developing and growing a decision tree, where each\nnode in the tree is a candidate sequence whose fitness is directly evaluated by\nmolecular simulations. We interface MCTS with MD simulations and use a\nrepresentative example of designing a copolymer compatibilizer, where the goal\nis to identify sequence specific copolymers that lead to zero interfacial\nenergy between two immiscible homopolymers. We apply the MCTS algorithm to\npolymer chain lengths varying from 10-mer to 30-mer, wherein the overall search\nspace varies from 210 (1024) to 230 (~1 billion). In each case, we identify a\ntarget sequence that leads to zero interfacial energy within a few hundred\nevaluations demonstrating the scalability and efficiency of MCTS in exploring\npractical materials design problems with exceedingly vast chemical/material\nsearch space. Our MCTS-MD framework can be easily extended to several other\npolymer and protein inverse design problems, in particular, for cases where\nsequence-property data is either unavailable and/or is resource intensive."
    },
    {
        "anchor": "Kinematics and dynamics of disclination lines in three-dimensional\n  nematics: An exact kinematic law for the motion of disclination lines in nematic liquid\ncrystals as a function of the tensor order parameter $\\mathbf{Q}$ is derived.\nUnlike other order parameter fields that become singular at their respective\ndefect cores, the tensor order parameter remains regular. Following earlier\nexperimental and theoretical work, the disclination core is defined to be the\nline where the uniaxial and biaxial order parameters are equal, or\nequivalently, where the two largest eigenvalues of $\\mathbf{Q}$ cross. This\nallows an exact expression relating the velocity of the line to spatial and\ntemporal derivatives of $\\mathbf{Q}$ on the line, to be specified by a\ndynamical model for the evolution of the nematic. By introducing a linear core\napproximation for $\\mathbf{Q}$, analytical results are given for several\nprototypical configurations, including line interactions and motion, loop\nannihilation, and the response to external fields and shear flows. Behaviour\nthat follows from topological constraints or defect geometry is highlighted.\nThe analytic results are shown to be in agreement with three dimensional\nnumerical calculations based on a singular Maier-Saupe free energy that allows\nfor anisotropic elasticity.",
        "positive": "Reply to Comment on \"Pipe network model for scaling of dynamic\n  interfaces in porous media'': Here we give further evidences to support our scaling relation described in\nour previous paper [cond-mat/0006459, Phys. Rev. Lett. Vol.85, pp.1238 (2000)]."
    },
    {
        "anchor": "Statics and diffusive dynamics of surfaces driven by $p$-atic\n  topological defects: Inspired by epithelial morphogenesis, we consider a minimal model for the\nshaping of a surface driven by $p$-atic topological defects. We show that a\npositive (negative) defect can dynamically generate a (hyperbolic) cone whose\nshape evolves diffusively, and predict that a defect of charge $+1/p$ leads to\na final semi-cone angle $\\beta$ which satisfies the inequality $\\sin\\beta \\ge 1\n- \\frac{1}{p} + \\frac{1}{2p^2}$. By exploiting the fact that for axisymmetric\nsurfaces, the extrinsic geometry is tightly coupled to the intrinsic geometry,\nwe further show that the resulting stationary shape of a membrane with\nnegligible bending modulus and embedded polar order is a deformed lemon with\ntwo defects at antipodal points. Finally, we close by pointing out that our\nresults may be relevant beyond epithelial morphogenesis in such contexts as\nshape transitions in macroscopic closed spheroidal surfaces such as pollen\ngrains.",
        "positive": "Defect Line Coarsening and Refinement in Active Nematics: Active matter is naturally out of equilibrium which results in the emergence\nof diverse dynamic steady states, including the omnipresent chaotic state known\nas the active turbulence. However, much less is known how active systems\ndynamically depart out of these configurations, such as get excited or damped\nto a different dynamic steady state. In this Letter, we demonstrate the\ncoarsening and refinement dynamics of topological defect lines in\nthree-dimensional active nematic turbulence. Specifically, using theory and\nnumerical modelling, we are able to predict the evolution of the active defect\ndensity away from the steady state due to time-dependent activity or\nviscoelastic material properties, establishing a single length scale\nphenomenological description of defect line coarsening/refinement in a\nthree-dimensional active nematic. The approach is first applied to growth\ndynamics of a single active defect loop, and then to a full three-dimensional\nactive defect network. More generally, this work provides insight into the\ngeneral coarsening phenomena between dynamical regimes in 3D active matter,\nwith a possible analogy in other physical systems."
    },
    {
        "anchor": "Elastic interactions between 2D geometric defects: In this paper, we introduce a methodology applicable to a wide range of\nlocalized two-dimensional sources of stress. This methodology is based on a\ngeometric formulation of elasticity. Localized sources of stress are viewed as\nsingular defects---point charges of the curvature associated with a reference\nmetric. The stress field in the presence of defects can be solved using a\nscalar stress function that generalizes the classical Airy stress function to\nthe case of materials with nontrivial geometry. This approach allows the\ncalculation of interaction energies between various types of defects. We apply\nour methodology to two physical systems: shear-induced failure of amorphous\nmaterials and the mechanical interaction between contracting cells.",
        "positive": "Kinetic theory and shear viscosity of dense dipolar hard sphere liquids: Transport properties of dense fluids are fundamentally challenging, because\nthe powerful approaches of equilibrium statistical physics cannot be applied.\nPolar fluids compound this problem, because the long-range interactions\npreclude the use of a simple effect-diameter approach based solely on hard\nspheres. Here, we develop a kinetic theory for dipolar hard-sphere fluids that\nis valid up to high density. We derive a mathematical approximation for the\nradial distribution function at contact directly from the equation of state,\nand use it to obtain the shear viscosity. We also perform molecular-dynamics\nsimulations of this system and extract the shear viscosity numerically. The\ntheoretical results compare favorably to the simulations."
    },
    {
        "anchor": "The effect of shear stress reduction on endothelial cells: a\n  microfluidic study of the actin cytoskeleton: Reduced blood flow, as occurring in ischemia or resulting from exposure to\nmicrogravity such as encountered in space flights, induces a decrease in the\nlevel of shear stress sensed by the endothelial cells forming the inner part of\nblood vessels. In the present study, we use a microvasculature-on-a-chip device\nin order to investigate in vitro the effect of such a reduction in shear stress\non shear-adapted endothelial cells. We find that, within one hour of exposition\nto reduced wall shear stress, human umbilical vein endothelial cells undergo a\nreorganization of their actin skeleton, with a decrease in the number of stress\nfibers and actin being recruited into the cells' peripheral band, indicating a\nfairly fast change in cells' phenotype due to altered flow.",
        "positive": "Variety of scaling behaviors in nanocrystalline plasticity: We address the question of why larger, high symmetry crystals are mostly\nweak, ductile and statistically sub-critical, while smaller crystals with the\nsame symmetry are strong, brittle and super-critical. We link it to another\nquestion of why intermittent elasto-plastic deformation of sub-micron crystals\nfeatures highly unusual size sensitivity of scaling exponents. We use a minimal\ninteger-valued automaton model of crystal plasticity to show that with growing\nvariance of quenched disorder, which can serve in this case as a proxy for\nincreasing size, sub-micron crystals undergo a crossover from spin-glass\nmarginality to criticality characterizing the second order brittle-to-ductile\n(BD) transition. We argue that this crossover is behind the non-universality of\nscaling exponents observed in physical and numerical experiments. The\nnon-universality emerges only if the quenched disorder is elastically\nincompatible and it disappears if the disorder is compatible."
    },
    {
        "anchor": "Dynamics of a mean spherical model with competing interactions: The Langevin dynamics of a $d$-dimensional mean spherical model with\ncompeting interactions along $m\\leq d$ directions of a hypercubic lattice is\nanalysed. After a quench at high temperatures, the dynamical behaviour is\ncharacterized by two distinct time scales associated with stationary and aging\nregimes. The asymptotic expressions for the autocorrelation and response\nfunctions, in supercritical, critical, and subcritical cases, were calculated.\nAging effects, which are known to be present in the ferromagnetic version of\nthis model system, are not affected by the introduction of competing\ninteractions.",
        "positive": "Effect of different monomer precursors with identical functionality on\n  the properties of the polymer network: Thermo-mechanical properties of polymer networks depend on functionality of\nthe monomer precursors -- an association that is frequently exploited in\nmaterials science. We use molecular simulations to generate spatial networks\nfrom chemically different monomers with identical functionality and show that\nsuch networks have several universal graph-theoretical properties as well as\nnear universal Young's modulus. The vitrification temperature is shown to be\nuniversal only up to a certain density of the network, as measured by the bond\nconversion. The latter observation is explained by the fact that monomer's\ntendency to coil enhances formation of topological holes, which, when\naccumulated in the network, amount to a percolating cell complex restricting\nnetwork's mobility. This higher-order percolation occurs late after gelation\nand is shown to coincide with the onset of brittleness, as indicated by a\nsudden increase in the glass transition temperature. This phenomenon may\nsignify a new type of phase transition in polymer materials."
    },
    {
        "anchor": "Scientific Machine Learning for Modeling and Simulating Complex Fluids: The formulation of rheological constitutive equations -- models that relate\ninternal stresses and deformations in complex fluids -- is a critical step in\nthe engineering of systems involving soft materials. While data-driven models\nprovide accessible alternatives to expensive first-principles models and less\naccurate empirical models in many engineering disciplines, the development of\nsimilar models for complex fluids has lagged. The diversity of techniques for\ncharacterizing non-Newtonian fluid dynamics creates a challenge for classical\nmachine learning approaches, which require uniformly structured training data.\nConsequently, early machine learning constitutive equations have not been\nportable between different deformation protocols or mechanical observables.\nHere, we present a data-driven framework that resolves such issues, allowing\nrheologists to construct learnable models that incorporate essential physical\ninformation, while remaining agnostic to details regarding particular\nexperimental protocols or flow kinematics. These scientific machine learning\nmodels incorporate a universal approximator within a materially objective\ntensorial constitutive framework. By construction, these models respect\nphysical constraints, such as frame-invariance and tensor symmetry, required by\ncontinuum mechanics. We demonstrate that this framework facilitates the rapid\ndiscovery of accurate constitutive equations from limited data, and that the\nlearned models may be used to describe more kinematically complex flows. This\ninherent flexibility admits the application of these 'digital fluid twins' to a\nrange of material systems and engineering problems. We illustrate this\nflexibility by deploying a trained model within a multidimensional\ncomputational fluid dynamics simulation -- a task that is not achievable using\nany previously developed data-driven rheological equation of state.",
        "positive": "A predictive model for fluid-saturated, brittle granular materials\n  during high-velocity impact events: Granular materials -- aggregates of many discrete, disconnected solid\nparticles -- are ubiquitous in natural and industrial settings. Predictive\nmodels for their behavior have wide ranging applications, e.g. in defense,\nmining, construction, pharmaceuticals, and the exploration of planetary\nsurfaces. In many of these applications, granular materials mix and interact\nwith liquids and gases, changing their effective behavior in non-intuitive\nways. Although such materials have been studied for more than a century, a\nunified description of their behaviors remains elusive.\n  In this work, we develop a model for granular materials and mixtures that is\nusable under particularly challenging conditions: high-velocity impact events.\nThis model combines descriptions for the many deformation mechanisms that are\nactivated during impact -- particle fracture and breakage; pore collapse and\ndilation; shock loading; and pore fluid coupling -- within a thermo-mechanical\nframework based on poromechanics and mixture theory. This approach allows for\nsimultaneous modeling of the granular material and the pore fluid, and includes\nboth their independent motions and their complex interactions. A general form\nof the model is presented alongside its specific application to two types of\nsands that have been studied in the literature. The model predictions are shown\nto closely match experimental observation of these materials through several\nGPa stresses, and simulations are shown to capture the different dynamic\nresponses of dry and fully-saturated sand to projectile impacts at 1.3 km/s."
    },
    {
        "anchor": "Quantitative cw Overhauser DNP Analysis of Hydration Dynamics: Liquid state Overhauser Effect Dynamic Nuclear Polarization (ODNP) has\nexperienced a recent resurgence of interest. In particular, a new manifestation\nof the ODNP measurement measures the translational mobility of water within\n5-10 \\AA\\ of an ESR-active spin probe (i.e. the local translational diffusivity\nD_{local} near an electron spin resonance active molecule). Such spin probes,\ntypically stable nitroxide radicals, have been attached to the surface or\ninterior of macromolecules, including proteins, polymers, and membrane\nvesicles. Despite the unique specificity of this measurement, it requires only\na standard X-band (~10 GHz) continuous wave (cw) electron spin resonance (ESR)\nspectrometer, coupled with a standard nuclear magnetic resonance (NMR)\nspectrometer. Here, we present a set of developments and corrections that allow\nus to improve the accuracy of quantitative ODNP and apply it to samples more\nthan two orders of magnitude lower than were previously feasible.",
        "positive": "An intermediate phase between jammed and un-jammed amorphous solids: A significant amount of attention was dedicated in recent years to the\nphenomenon of jamming of athermal amorphous solids by increasing the volume\nfraction of the microscopic constituents. At a critical value of the volume\nfraction, pressure shoots up from zero to finite values with a host of critical\nexponents discovered and discussed. In this letter, we advance evidence for the\nexistence of a second transition, within the jammed state of two-dimensional\ngranular systems, that separates two phases characterized by different\nmechanical screening regimes. Explicitly, highly packed systems are\nquasi-elastic with quadrupole-screening, and more loosely jammed systems\nexhibit anomalous mechanics with dipole screening. Evidence is given for a\nclear transition between these two regimes, reminiscent of the intermediate\nhexatic phase of crystal melting in two-dimensional crystals."
    },
    {
        "anchor": "Questioning the relationship between the $\u03c7$4 susceptibility and the\n  dynamical correlation length in a glass former: Clusters of fast and slow correlated particles, identified as dynamical\nheterogeneities (DHs), con-stitute a central aspect of glassy dynamics. A key\ningredient of the glass transition scenario is asignificant increase of the\ncluster size $\\xi$4 as the transition is approached. In need of\neasy-to-computetools to measure $\\xi$4 , the dynamical susceptibility $\\chi$4\nwas introduced recently, and used in various ex-perimental works to probe DHs.\nHere, we investigate DHs in dense microgel suspensions using imagecorrelation\nanalysis, and compute both $\\chi$4 and the four-point correlation function G4 .\nThe spatialdecrease of G4 provides a direct access to $\\xi$4 , which is found\nto grow significantly with increasingvolume fraction. However, this increase is\nnot captured by $\\chi$4 . We show that the assumptions thatvalidate the\nconnection between $\\chi$4 and $\\xi$4 are not fulfilled in our experiments.",
        "positive": "Energy Landscape, Anti-Plasticization and Polydispersity Induced\n  Crossover of Heterogeneity in Supercooled Polydisperse Liquids: Polydispersity is found to have a significant effect on the potential energy\nlandscape; the the average inherent structure energy with temperature decreases\nwith polydispersity. Increasing polydispersity at fixed volume fraction\ndecreases the glass transition temperature and the fragility of glass formation\nanalogous to the antiplasticization seen in some polymeric melts. An\ninteresting temperature dependent crossover of heterogeneity with\npolydispersity is observed at low temperature due to the faster build-up of\ndynamic heterogeneity at lower polydispersity."
    },
    {
        "anchor": "Dynamic regimes of fluids simulated by multiparticle-collision dynamics: We investigate the hydrodynamic properties of a fluid simulated with a\nmesoscopic solvent model. Two distinct regimes are identified, the `particle\nregime' in which the dynamics is gas-like, and the `collective regime' where\nthe dynamics is fluid-like. This behavior can be characterized by the Schmidt\nnumber, which measures the ratio between viscous and diffusive transport.\nAnalytical expressions for the tracer diffusion coefficient, which have been\nderived on the basis of a molecular-chaos assumption, are found to describe the\nsimulation data very well in the particle regime, but important deviations are\nfound in the collective regime. These deviations are due to hydrodynamic\ncorrelations. The model is then extended in order to investigate self-diffusion\nin colloidal dispersions. We study first the transport properties of heavy\npoint-like particles in the mesoscopic solvent, as a function of their mass and\nnumber density. Second, we introduce excluded-volume interactions among the\ncolloidal particles and determine the dependence of the diffusion coefficient\non the colloidal volume fraction for different solvent mean-free paths. In the\ncollective regime, the results are found to be in good agreement with previous\ntheoretical predictions based on Stokes hydrodynamics and the Smoluchowski\nequation.",
        "positive": "Collective diffusion coefficient of a charged colloidal dispersion:\n  interferometric measurements in a drying drop: In the present work, we use Mach-Zehnder interferometry to thoroughly\ninvestigate the drying dynamics of a 2D confined drop of a charged colloidal\ndispersion. This technique makes it possible to measure the colloid\nconcentration field during the drying of the drop at a high accuracy (about\n0.5%) and with a high temporal and spatial resolution (about 1 frame/s and 5\n$\\mu$m/pixel). These features allow us to probe mass transport of the charged\ndispersion in this out-of-equilibrium situation. In particular, our experiments\nprovide the evidence that mass transport within the drop can be described by a\npurely diffusive process for some range of parameters for which the\nbuoyancy-driven convection is negligible. We are then able to extract from\nthese experiments the collective diffusion coefficient of the dispersion\n$D(\\varphi)$ over a wide concentration range $\\varphi=0.24$-$0.5$, i.e. from\nthe liquid dispersed state to the solid glass regime, with a high accuracy. The\nmeasured values of $D(\\varphi)\\simeq 5$-$12 D_0$ are significantly larger than\nthe simple estimate $D_0$ given by the Stokes-Einstein relation, thus\nhighlighting the important role played by the colloidal interactions in such\ndispersions."
    },
    {
        "anchor": "Solidification of the Lennard-Jones fluid near the wall in\n  thermohydrodynamic lubrication: We investigate the thermohydrodynamic lubrication of the Lennard-Jones (LJ)\nfluid in the parallel-plate channel composed of the LJ particles by using\nmolecular dynamics (MD) simulation. We discover a counterintuitive\nsolidification of the LJ fluid near the wall, i.e., \\textit{viscous\nheating-induced solidification}, where solidification occurs only when the\nviscous heating of the LJ fluid is sufficiently large. The solidification\nmechanism is investigated from both macroscopic and microscopic points of view.\nIt is found that the LJ molecules are densely confined in the vicinity of the\nwall via the thermohydrodynamic transport of the bulk fluid and that when the\nlocal density in the vicinity of the wall is close to the solidification line\nin the phase diagram, the LJ molecules are solidified due to the interaction\nwith the crystallized wall molecules. Band formation is also observed in the\nhighly confined regime when the channel width is sufficiently large.",
        "positive": "The direct correlation function of a crystalline solid: Direct correlation functions (DCFs), linked to the second functional\nderivative of the free energy with respect to the one-particle density, play a\nfundamental role in a statistical mechanics description of matter. This holds\nin particular for the ordered phases: DCFs contain information about the local\nstructure including defects and encode the thermodynamic properties of\ncrystalline solids; they open a route to the elastic constants beyond low\ntemperature expansions. Via a numerical tour de force we have explicitly\ncalculated for the first time the DCF of a solid: based on the fundamental\nmeasure concept we provide results for the DCF of a hard sphere crystal. We\ndemonstrate that this function differs at coexistence significantly from its\nliquid counterpart - both in shape as well as in its order of magnitude -\nbecause it is dominated by vacancies. We provide evidence that the traditional\nuse of liquid DCFs in functional Taylor expansions of the free energy is\nconceptually wrong and show that the emergent elastic constants are in good\nagreement with simulation-based results."
    },
    {
        "anchor": "Density Functional Theory of a Curved Liquid-Vapour Interface:\n  Evaluation of the rigidity constants: It is argued that to arrive at a quantitative description of the surface\ntension of a liquid drop as a function of its inverse radius, it is necessary\nto include the bending rigidity k and Gaussian rigidity k_bar in its\ndescription. New formulas for k and k_bar in the context of density functional\ntheory with a non-local, integral expression for the interaction between\nmolecules are presented. These expressions are used to investigate the\ninfluence of the choice of Gibbs dividing surface and it is shown that for a\none-component system, the equimolar surface has a special status in the sense\nthat both k and k_bar are then the least sensitive to a change in the location\nof the dividing surface. Furthermore, the equimolar value for k corresponds to\nits maximum value and the equimolar value for k_bar corresponds to its minimum\nvalue. An explicit evaluation using a short-ranged interaction potential\nbetween molecules, shows that k is negative with a value around minus 0.5-1.0\nkT and that k_bar is positive with a value which is a bit more than half the\nmagnitude of k. Finally, for dispersion forces between molecules, we show that\na term proportional to log(R)/R^2 replaces the rigidity constants and we\ndetermine the (universal) proportionality constants.",
        "positive": "Topological structure and dynamics of three dimensional active nematics: Point-like motile topological defects control the universal dynamics of\ndiverse two-dimensional active nematics ranging from shaken granular rods to\ncellular monolayers. A comparable understanding in higher dimensions has yet to\nemerge. We report the creation of three-dimensional active nematics by\ndispersing extensile microtubule bundles in a passive colloidal liquid crystal.\nLight-sheet microscopy reveals the millimeter-scale structure of active\nnematics with a single bundle resolution and the temporal evolution of the\nassociated nematic director field. The dominant excitations of\nthree-dimensional active nematics are extended charge-neutral disclination\nloops that undergo complex dynamics and recombination events. These studies\nintroduce a new class of non-equilibrium systems whose turbulent-like dynamics\narises from the interplay between internally generated active stresses, the\nchaotic flows and the topological structure of the constituent defects."
    },
    {
        "anchor": "Mesoscopic Simulations of Active-Nematics: Coarse-grained, mesoscale simulations are invaluable for studying soft\ncondensed matter because of their ability to model systems in which a\nbackground solvent plays a significant role but is not the primary interest.\nSuch methods generally model passive solvents; however, far-from-equilibrium\nsystems may also be composed of complex solutes suspended in an active fluid.\nYet, few coarse-grained simulation methods exist to model an active medium. We\nintroduce an algorithm to simulate active nematics, which builds on\nmulti-particle collision dynamics (MPCD) for passive fluctuating\nnematohydrodynamics by introducing dipolar activity in the local collision\noperator. Active-nematic MPCD (AN-MPCD) simulations exhibit the key\ncharacteristics of active nematic turbulence but, as a particle-based\nalgorithm, also reproduce crucial attributes of active particle models. Thus,\nmesoscopic AN-MPCD is an approach that bridges microscopic and continuum\ndescriptions, allowing novel simulations of composite active-passive systems.",
        "positive": "Fluids of spherical molecules with dipolar-like nonuniform adhesion. An\n  analytically solvable anisotropic model: We consider an anisotropic version of Baxter's model of `sticky hard\nspheres', where a nonuniform adhesion is implemented by adding, to an isotropic\nsurface attraction, an appropriate `dipolar sticky' correction (positive or\nnegative, depending on the mutual orientation of the molecules). The resulting\nnonuniform adhesion varies continuously, in such a way that in each molecule\none hemisphere is `stickier' than the other. We derive a complete analytic\nsolution by extending a formalism [M.S. Wertheim, J. Chem. Phys. \\textbf{55},\n4281 (1971) ] devised for dipolar hard spheres. Unlike Wertheim's solution\nwhich refers to the `mean spherical approximation', we employ a\n\\textit{Percus-Yevick closure with orientational linearization}, which is\nexpected to be more reliable. We obtain analytic expressions for the\norientation-dependent pair correlation function $g(1,2) $. Only one equation\nfor a parameter $K$ has to be solved numerically. We also provide very accurate\nexpressions which reproduce $K$ as well as some parameters, $\\Lambda_{1}$ and\n$\\Lambda_{2}$, of the required Baxter factor correlation functions with a\nrelative error smaller than 1%. We give a physical interpretation of the\neffects of the anisotropic adhesion on the $g(1,2) $. The model could be useful\nfor understanding structural ordering in complex fluids within a unified\npicture."
    },
    {
        "anchor": "Stress Response in Confined Arrays of Frictional and Frictionless\n  Particles: Stress transmission inside three dimensional granular packings is\ninvestigated using computer simulations. Localized force perturbation\ntechniques are implemented for frictionless and frictional shallow, ordered,\ngranular arrays confined by solid boundaries for a range of system sizes.\nStress response profiles for frictional packings agree well with the\npredictions for the semi-infinite half plane of classical isotropic elasticity\ntheory down to boxes of linear dimensions of approximately forty particle\ndiameters and over several orders of magnitude in the applied force. The\nresponse profiles for frictionless packings exhibit a transitional regime to\nstrongly anisotropic features with increasing box size. The differences between\nthe nature of the stress response are shown to be characterized by very\ndifferent particle displacement fields.",
        "positive": "Fluid-Glass-Jamming Rheology of Soft Active Brownian Particles: We numerically study the shear rheology of a binary mixture of soft Active\nBrownian Particles, from the fluid to the disordered solid regime. At low shear\nrates, we find a Newtonian regime, where a Green-Kubo relation with an\neffective temperature provides the linear viscosity. It is followed by a\nshear-thinning regime at larger shear rates. At high densities, solidification\nis signalled by the emergence of a finite yield stress. We construct a\n\"fluid-glass-jamming\" phase diagram with activity replacing temperature. While\nboth parameters gauge fluctuations, activity also changes the exponent\ncharacterizing the decay of the diffusivity close to the glass transition and\nthe shape of the yield stress surface. The dense disordered active solid\nappears to be mostly dominated by athermal jamming rather than glass rheology."
    },
    {
        "anchor": "Translational Diffusion of Polymer Chains with Excluded Volume and\n  Hydrodynamic Interactions by Brownian Dynamics Simulation: Within Kirkwood theory, we study the translational diffusion coefficient of a\nsingle polymer chain in dilute solution, and focus on the small difference\nbetween the short--time Kirkwood value $D^{(K)}$ and the asymptotic long--time\nvalue $D$. We calculate this correction term by highly accurate large--scale\nBrownian Dynamics simulations, and show that it is in perfect agreement with\nthe rigorous variational result $D < D^{(K)}$, and with Fixman's Green--Kubo\nformula, which is re--derived. This resolves the puzzle posed by earlier\nnumerical results (Rey {\\em et al.}, Macromolecules 24, 4666 (1991)), which\nrather seemed to indicate $D > D^{(K)}$; the older data are shown to have\ninsufficient statistical accuracy to resolve this question. We then discuss the\nGreen--Kubo integrand in some detail. This function behaves very differently\nfor pre--averaged vs. fluctuating hydrodynamics, as shown for the initial value\nby analytical considerations corroborated by numerical results. We also present\nfurther numerical data on the chain's statics and dynamics.",
        "positive": "Debonding of a soft adhesive fibril in contact with an elastomeric\n  pillar: The debonding criterion of fibrils of soft adhesive materials is a key\nelement regarding the quantitative modelisation of pressure sensitive adhesive\ntapes peeling energy. We present in this article an experimental study of the\ndetachment of a commercial acrylic adhesive tape from the top surface of a\nsingle micrometric pillar of PDMS elastomer. During an experiment, the pillar\nand the adhesive, after being put in contact, are separated at a constant\ndisplacement rate, resulting in the formation, the elongation and the final\ndetachment of a fibril of adhesive material. A systematic study allows us to\nuncover power laws for the maximum force and the critical elongation of the\nfibril at debonding as a function of the diameter of the cylindrical pillar\nwhich controls the diameter of the fibril. The scaling law evidenced for the\ncritical elongation appears as a first step toward the understanding of the\ndebonding criterion of fibrils of soft adhesive materials. In addition,\nviscoelastic digitation at the triple debonding line is observed during\ndetachment for large pillar diameters. The wavelength and penetration length of\nthe fingers that we report appear to be consistent with existing models based\non pure elastic mechanical response."
    },
    {
        "anchor": "Heat Conduction in Polymer Chains: Effect of Substrate on the Thermal\n  Conductance: In standard molecular junctions, a molecular structure is placed between and\nconnected to metal leads. Understanding how mechanical tuning in such molecular\njunctions can change heat conductance has interesting applications in nanoscale\nenergy transport. In this work, we use nonequilibrium molecular dynamics\nsimulations to address the effect of stretching on the phononic contribution to\nthe heat conduction of molecular junctions consisting of single long-chain\nalkanes and various metal leads such as Ag, Au, Cu, Ni, and Pt. The thermal\nconductance of such junctions is found to be much smaller than the intrinsic\nthermal conductance of the polymer and significantly depends on the nature of\nmetal leads as expressed by the metal-molecule coupling and metal vibrational\ndensity of states. This behavior is expected and reflects the mismatch of\nphonon spectra at the metal molecule interfaces. As a function of stretching,\nwe find a behavior similar to what was observed earlier [J. Chem. Phys. 153,\n164903 (2020)] for pure polymeric structures. At relatively short electrode\ndistances, where the polyethylene chains are compressed, it is found that the\nthermal conductances of the molecular junctions remain almost constant as one\nstretches the polymer chains. At critical electrode distances, the thermal\nconductances start to increase, reaching the values of the fully-extended\nmolecular junctions. Similar behaviors are observed for junctions in which\nseveral long-chain alkanes are sandwiched between various metal leads.\n  These findings indicate that this behavior under stretching is an intrinsic\nproperty of the polymer chain and not significantly associated with the\ninterfacial structures.",
        "positive": "An extreme case of density scaling: The Weeks-Chandler-Andersen system\n  at low temperatures: This paper studies numerically the Weeks-Chandler-Andersen (WCA) system,\nwhich is shown to obey hidden scale invariance with a density-scaling exponent\nthat varies from below 5 to above 500. This unprecedented variation makes it\nadvantageous to use the fourth-order Runge-Kutta algorithm for tracing out\nisomorphs. Good isomorph invariance of structure and dynamics is observed over\nmore than three orders of magnitude temperature variation. For all state points\nstudied, the virial potential-energy correlation coefficient and the\ndensity-scaling exponent are controlled mainly by the temperature. Based on the\nassumption of statistically independent pair interactions, a mean-field theory\nis developed that rationalizes this finding and provides an excellent fit to\ndata at low temperatures and densities."
    },
    {
        "anchor": "Inertial drag in granular media: Like in liquids, objects moving in granular materials experience a drag\nforce. We investigate here whether and how the object acceleration affect this\ndrag force. The study is based on simulations of a canonical drag test, which\ninvolves vertically uplifting a plate through a granular packing with a\nprescribed acceleration pattern. Depending on the plate size, plate depth and\nacceleration pattern, results evidence a rate-independent regime and an\ninertial regime where the object acceleration strongly enhances the drag force.\nWe introduce an elasto-inertial drag force model that captures the measured\ndrag forces in these two regimes. The model is based on observed physical\nprocesses including a gradual, elasto-inertial mobilisation of grains located\nabove the plate. These results and analysis point out fundamental differences\nbetween mobility in granular materials upon steady and unsteady loadings.",
        "positive": "Thermal-driven Flow inside Graphene Channels for Water Desalination: A novel concept of membrane process in thermal-driven system is proposed for\nwater desalination. By means of molecular dynamics simulations, we show fast\nwater transport through graphene galleries at a temperature gradient. Water\nmolecules are driven to migrate through nanometer-wide graphene channels from\ncold reservoir to hot reservoir by the effect of thermal creep flow. Reducing\nthe interlayer spacing to 6.5 {\\AA}, an abrupt escalation occurs in water\npermeation between angstrom-distance graphene slabs. The change from disordered\nbulklike water to quasi-square structure have been found under this extremely\nconfined condition. This leads to a transition to subcontinuum transport. Water\nmolecules perform collective diffusion behaviors inside graphene channels. The\nspecial transport processes with structure change convert thermal energy into\nmotion without dissipation, resulting in unexpected high water permeability.\nThe thermal-driven system reaches maximum flowrate at temperature variance of\n80 K, corresponding to the quantity at pressure difference up to 10^5 bar in\ncommercial reverse osmosis processes and 230 bar in pressure-driven slip flow.\nOur results also reveal the movement of saline ions influenced by\nthermophoretic effect, which complement the geometry limitation at greater\nlayer spacing, enhancing the blockage of ions. This finding aims to provide an\ninnovational idea of developing a high-efficiency desalination technology able\nto utilize various forms of energy."
    },
    {
        "anchor": "Microstructure of a liquid complex (dusty) plasma under shear: The microstructure of a strongly coupled liquid undergoing a shear flow was\nstudied experimentally. The liquid was a shear melted two-dimensional plasma\ncrystal, i.e., a single-layer suspension of micrometer-size particles in a rf\ndischarge plasma. Trajectories of particles were measured using video\nmicroscopy. The resulting microstructure was anisotropic, with compressional\nand extensional axes at around $\\pm 45^{\\circ}$ to the flow direction.\nCorresponding ellipticity of the pair correlation function $g({\\bf r})$ or\nstatic structure factor $S(\\bf{k})$ gives the (normalized) shear rate of the\nflow.",
        "positive": "First-principles study of orthorhombic CdTiO3 perovskite: In this work we perform an ab-initio study of CdTiO3 perovskite in its\northorhombic phase using FLAPW method. Our calculations help to decide between\nthe different cristallographic structures proposed for this perovskite from\nX-Ray measurements. We compute the electric field gradient tensor (EFG) at Cd\nsite and obtain excellent agreement with available experimental information\nfrom a perturbed angular correlation (PAC) experiment. We study EFG under an\nisotropic change of volume and show that in this case the widely used \"point\ncharge model approximation\" to determine EFG works quite well."
    },
    {
        "anchor": "Topological defect coarsening in quenched smectic-C films analyzed using\n  artificial neural networks: Mechanically quenching a thin film of smectic-C liquid crystal results in the\nformation of a dense array of thousands of topological defects in the director\nfield. The subsequent rapid coarsening of the film texture by the mutual\nannihilation of defects of opposite sign has been captured using high-speed,\npolarized light video microscopy. The temporal evolution of the texture has\nbeen characterized using an object-detection convolutional neural network to\ndetermine the defect locations, and a binary classification network customized\nto evaluate the brush orientation dynamics around the defects in order to\ndetermine their topological signs. At early times following the quench,\ninherent limits on the spatial resolution result in undercounting of the\ndefects and deviations from expected behavior. At intermediate to late times,\nthe observed annihilation dynamics scale in agreement with theoretical\npredictions and simulations of the $2$D XY model.",
        "positive": "Clusters of microparticles in distilled water: a kaleidoscope of\n  versions and paradoxes of nature (Review): The presence of microparticles (clusters of micron size) of unknown origin in\nthe volume of water, including highly purified water (bidistilled, deionized),\nhas been repeatedly demonstrated by various methods of physical analysis.\nVarious assumptions have been made about the nature of these microparticles,\nbut none of them has become generally accepted. The review analyzes the\nliterature data and the results obtained by the authors using optical and\nelectron scanning microscopes. The composition and phase state of distilled\nwater deposits at the bottom of glassware after evaporation of free water are\nconsidered. The structure of the microdispersed phase of distilled water and\nthe mechanism of phase transitions of its components in the process of natural\nevaporation, the end products of which are gel-like water and sodium chloride\ncrystals, are proposed."
    },
    {
        "anchor": "Absence of Red Structural Color in Photonic Glasses, Bird Feathers and\n  Certain Beetles: Colloidal glasses, bird feathers, and beetle scales can all show structural\ncolors arising from short-ranged spatial correlations between scattering\ncenters. Unlike the structural colors arising from Bragg diffraction in ordered\nmaterials like opals, the colors of these photonic glasses are independent of\norientation, owing to their disordered, isotropic microstructures. However,\nthere are few examples of photonic glasses with angle-independent red colors in\nnature, and colloidal glasses with particle sizes chosen to yield structural\ncolors in the red show weak color saturation. Using scattering theory, we show\nthat the absence of angle-independent red color can be explained by the\ntendency of individual particles to backscatter light more strongly in the\nblue. We discuss how the backscattering resonances of individual particles\narise from cavity-like modes, and how they interact with the structural\nresonances to prevent red. Finally, we use the model to develop design rules\nfor colloidal glasses with red, angle-independent structural colors.",
        "positive": "Transient stress evolution in repulsion and attraction dominated glasses: We present results from microscopic mode coupling theory generalized to\ncolloidal dispersions under shear in an integration-through-transients\nformalism. Stress-strain curves in start-up shear, flow curves, and normal\nstresses are calculated with the equilibrium static structure factor as only\ninput. Hard spheres close to their glass transition are considered, as are hard\nspheres with a short-ranged square-well attraction at their attraction\ndominated glass transition. The consequences of steric packing and physical\nbond formation on the linear elastic response, the stress release during\nyielding, and the steady plastic flow are discussed and compared to\nexperimental data from concentrated model dispersions."
    },
    {
        "anchor": "Origami building blocks: generic and special 4-vertices: Four rigid panels connected by hinges that meet at a point form a 4-vertex,\nthe fundamental building block of origami metamaterials. Here we show how the\ngeometry of 4-vertices, given by the sector angles of each plate, affects their\nfolding behavior. For generic vertices, we distinguish three vertex types and\ntwo subtypes. We establish relationships based on the relative sizes of the\nsector angles to determine which folds can fully close and the possible\nmountain-valley assignments. Next, we consider what occurs when sector angles\nor sums thereof are set equal, which results in 16 special vertex types. One of\nthese, flat-foldable vertices, has been studied extensively, but we show that a\nwide variety of qualitatively different folding motions exist for the other 15\nspecial and 3 generic types. Our work establishes a straightforward set of\nrules for understanding the folding motion of both generic and special\n4-vertices and serves as a roadmap for designing origami metamaterials.",
        "positive": "Liquid Crystalline Polymer Vesicles: Thermotropic Phases in Lyotropic\n  Structures: This paper reviews the research work on the liquid crystalline (LC) polymer\nvesicles (polymersomes), where the thermotropic nematic and smectic phases are\ndisplayed in the lyotropic bilayer polymer membrane. LC polymersomes possess\nthe properties of both liquid crystals and polymers, the two essential soft\nmatters. LC polymersomes offer, on the one hand, novel examples of the\ninterplay between orientational order and the curved geometry of a two\ndimensional membrane. Spherical, ellipsoidal and tetrahedral vesicles are\ndiscussed. On the other hand, LC polymersomes enable novel design of\nstimuli-responsive polymersomes using intramolecular conformational transition\nfrom nematic to isotropic phase of LC blocks. Photo-responsive polymersome\nbursting is highlighted."
    },
    {
        "anchor": "Edge Mode Amplification in Disordered Elastic Networks: We study theoretically and numerically the propagation of a displacement\nfield imposed at the edge of a disordered elastic material. While some modes\ndecay with some inverse penetration depth $\\kappa$, other exponentially {\\it\namplify} with rate $|\\kappa|$, where $\\kappa$'s are Lyapounov exponents\nanalogous to those governing electronic transport in a disordered conductors.\nWe obtain an analytical approximation for the full distribution $g(\\kappa)$,\nwhich decays exponentially for large $|\\kappa|$ and is finite when\n$\\kappa\\rightarrow0$. Our analysis shows that isostatic materials generically\nact as levers with possibly very large gains, suggesting a novel principle to\ndesign molecular machines that behave as elastic amplifiers.",
        "positive": "Characterization and Control of the Run-and-Tumble Dynamics of {\\it\n  Escherichia Coli}: We characterize the full spatiotemporal gait of populations of swimming {\\it\nEscherichia coli} using renewal processes to analyze the measurements of\nintermediate scattering functions. This allows us to demonstrate quantitatively\nhow the persistence length of an engineered strain can be controlled by a\nchemical inducer and to report a controlled transition from perpetual tumbling\nto smooth swimming. For wild-type {\\it E.~coli}, we measure simultaneously the\nmicroscopic motility parameters and the large-scale effective diffusivity,\nhence quantitatively bridging for the first time small-scale directed swimming\nand macroscopic diffusion."
    },
    {
        "anchor": "Reduction to the Simplest - The Complexity of Minimalistic Heteropolymer\n  Models: Simple coarse-grained hydrophobic-polar models for heteropolymers as the\nlattice HP and the off-lattice AB model allow a general classification of\ncharacteristic behaviors for hydrophobic-core based tertiary folding. The\nstrongly reduced computational efforts enable one to reveal systematically the\nthermodynamic properties of comparatively long sequences in a wide temperature\nrange of conformational activity. Based on a suitable cooperativity parameter,\ncharacteristic folding channels and free-energy landscapes, which have strong\nsimilarities with realistic folding paths, can be analysed.",
        "positive": "Slow and remanent electric polarization of adsorbed BSA layer evidenced\n  by neutron reflection: Using neutron reflectivity together with an appropriate electrochemical cell,\nwe have studied the effects of transverse electric field on the Bovine Serum\nAlbumin (BSA) monolayer initially adsorbed at the interface of the aqueous\nsolution and a conductive doped-silicon wafer. Depending on the sign of the\ninitial potential, a second layer is adsorbed on top of the first whereas a\nsubsequent reversal of potential has no effect. We show that this behavior\nreveals the slow and remanent electric polarization of the first BSA layer and\nsuggest an analogy with spin glasses based on the dipolar structure of this\nprotein."
    },
    {
        "anchor": "Clustering in anomalous files of independent particles: The dynamics of classical hard particles in a quasi one-dimensional channel\nwere studied since the 1960s and used for explaining processes in chemistry,\nphysics and biology and in applications. Here we show that in a previously\nun-described file made of anomalous, independent, particles (with jumping times\ntaken from, {\\psi}_{\\alpha} (t) t^(-1-{\\alpha}), 0<{\\alpha}<1), particles form\nclusters. At steady state, the percentage of particles in clusters is about,\n\\surd(1-{\\alpha}^3), only for anomalous {\\alpha}, characterizing the\ncriticality of a phase transition. The asymptotic mean square displacement per\nparticle in the file is about, log^2(t). We show numerically that this exciting\nphenomenon of a phase transition is very stable, and relate it with the\nmysterious phenomenon of rafts in biological membranes, and with regulation of\nbiological channels.",
        "positive": "Non-equilibrium melting of colloidal crystals in confinement: We report on a novel and flexible experiment to investigate the\nnon-equilibrium melting behaviour of model crystals made from charged colloidal\nspheres. In a slit geometry polycrystalline material formed in a low salt\nregion is driven by hydrostatic pressure up an evolving gradient in salt\nconcentration and melts at large salt concentration. Depending on particle and\ninitial salt concentration, driving velocity and the local salt concentration\ncomplex morphologic evolution is observed. Crystal-melt interface positions and\nthe melting velocity are obtained quantitatively from time resolved Bragg- and\npolarization microscopic measurements. A simple theoretical model predicts the\ninterface to first advance, then for balanced drift and melting velocities to\nbecome stationary at a salt concentration larger than the equilibrium melting\nconcentration. It also describes the relaxation of the interface to its\nequilibrium position in a stationary gradient after stopping the drive in\ndifferent manners. We further discuss the influence of the gradient strength on\nthe resulting interface morphology and a shear induced morphologic transition\nfrom polycrystalline to oriented single crystalline material before melting."
    },
    {
        "anchor": "Packing grains by thermally cycling: One of the oldest and most intriguing problems in the handling of materials\nis how a collection of solid grains packs together. While granular packing is\nnormally determined by how grains are poured or shaken, we find that a\nsystematic and controllable increase in packing is induced by simply raising\nand lowering the temperature, e.g., without the input of mechanical energy. The\nresults demonstrate that thermal processing provides a largely unexplored\nmechanism of grain dynamics, as well as an important practical consideration in\nthe handling and storage of granular materials.",
        "positive": "The anomalous distributions and Soret coefficient in a nonequilibrium\n  colloid system: The density distributions and Soret coefficient in a nonequilibrium colloidal\nsystem with nonuniform temperature are studied by the overdamped Langevin\nequation for Brownian motion in an inhomogeneous strong friction medium. Based\non the relation between the temperature gradient, the interaction potential and\nthe q-parameter in nonextensive statistics, We show that the colloidal particle\ndensity can be a function of the temperature and anomalously follows the noted\nalpha-distribution, or equivalently it can also be a function of the potential\nenergy and follows Tsallis distribution. With the q-parameter we can establish\na new formula of the Soret coefficient and thus, bridge the gap between the\nideally theoretical Soret coefficient and available experiments."
    },
    {
        "anchor": "Dynamic heterogeneities in attractive colloids: We study the formation of a colloidal gel by means of Molecular Dynamics\nsimulations of a model for colloidal suspensions. A slowing down with gel-like\nfeatures is observed at low temperatures and low volume fractions, due to the\nformation of persistent structures. We show that at low volume fraction the\ndynamic susceptibility, which describes dynamic heterogeneities, exhibits a\nlarge plateau, dominated by clusters of long living bonds. At higher volume\nfraction, where the effect of the crowding of the particles starts to be\npresent, it crosses over towards a regime characterized by a peak. We introduce\na suitable mean cluster size of clusters of monomers connected by \"persistent\"\nbonds which well describes the dynamic susceptibility.",
        "positive": "Competition of Brazil nut effect, buoyancy, and inelasticity induced\n  segregation in a granular mixture: It has been recently reported that a granular mixture in which grains differ\nin their restitution coefficients presents segregation: the more inelastic\nparticles sink to the bottom. When other segregation mechanisms as buoyancy and\nthe Brazil nut effect are present, the inelasticity induced segregation can\ncompete with them. First, a detailed analysis, based on numerical simulations\nof two dimensional systems, of the competition between buoyancy and the\ninelasticity induced segregation is presented, finding that there is a\ntransition line in the parameter space that determines which mechanism is\ndominant. In the case of neutrally buoyant particles having different sizes the\ninelasticity induced segregation can compete with the Brazil nut effect (BNE).\nReverse Brazil nut effect (RBNE) could be obtained at large inelasticities of\nthe intruder. At intermediate values, BNE and RBNE coexist and large inelastic\nparticles are found both near the bottom and at the top of the system."
    },
    {
        "anchor": "Topological-defect-induced surface charge heterogeneities in nematic\n  electrolytes: We show that topological defects in an ion-doped nematic liquid crystal can\nbe used to manipulate the surface charge distribution on chemically\nhomogeneous, charge-regulating external surfaces, using a minimal theoretical\nmodel. In particular, the location and type of the defect encodes the precise\ndistribution of surface charges and the effect is enhanced when the liquid\ncrystal is flexoelectric. We demonstrate the principle for patterned surfaces\nand charged colloidal spheres. More generally, our results indicate an\ninteresting approach to control surface charges on external surfaces without\nchanging the surface chemistry.",
        "positive": "Continuum Mechanical Modeling of Strain-Induced Crystallization in\n  Polymers: The present contribution focuses on the thermodynamically consistent\nmechanical modeling of the strain-induced crystallization in unfilled polymers.\nThis phenomenon is of particular importance for the mechanical properties of\npolymers as well as for their manufacturing and the application. The model\ndeveloped uses the principle of the minimum of dissipation potential and\nassumes two internal variables: the deformations due to crystallization and the\nregularity of the network. In addition to the dissipation potential necessary\nfor the derivation of evolution equations, the well-established Arruda-Boyce\nmodel is chosen to depict the elastic behavior of the polymer. Two special\nfeatures of the model are the evolution direction depending on the stress state\nand the distinction of crystallization during the loading and unloading phase.\nThe model has been implemented into the finite element method and applied for\nnumerical simulation of the growth and shrinkage of the crystal regions during\na cyclic tension test for samples with different initial configurations. The\nconcept enables the visualization of the microstructure evolution, yielding\ninformation that is still inaccessible by experimental techniques."
    },
    {
        "anchor": "Electrostatics in dissipative particle dynamics using Ewald sums with\n  point charges: A proper treatment of electrostatic interactions is crucial for the accurate\ncalculation of forces in computer simulations. Electrostatic interactions are\ntypically modeled using Ewald based methods, which have become one of the\ncornerstones upon which many other methods for the numerical computation of\nelectrostatic interactions are based. However, their use with charge\ndistributions rather than point charges requires the inclusion of ansatz for\nthe solutions of the Poisson equation, since there is no exact solution known\nfor smeared out charges. The interest for incorporating electrostatic\ninteractions at the scales of length and time that are relevant for the study\nthe physics of soft condensed matter has increased considerably. Using\nmesoscale simulation techniques, such as dissipative particle dynamics (DPD),\nallows us to reach longer time scales in numerical simulations, without\nabandoning the particulate description of the problem. The main problem with\nincorporating electrostatics into DPD simulations is that DPD particles are\nsoft and those particles with opposite charge can form artificial clusters of\nions. Here we show that one can incorporate the electrostatic interactions\nthrough Ewald sums with point charges in DPD if larger values of coarse\ngraining degree are used, where DPD is truly mesoscopic. Using point charges\nwith larger excluded volume interactions the artificial formation of ionic\npairs with point charges can be avoided, and one obtains correct predictions.\nWe establish ranges of parameters useful for detecting boundaries where\nartificial formation of ionic pairs occurs. Lastly, using point charges we\npredict the scaling properties of polyelectrolytes in solvents of varying\nquality and obtain predictions that are in agreement with calculations that use\nother methods, and with recent experimental results.",
        "positive": "Nemato-elasticity of hybrid molecular-colloidal liquid crystals: Colloidal rods immersed in a thermotropic liquid-crystalline solvent are at\nthe basis of so-called hybrid liquid crystals which are characterized by\ntunable nematic fluidity with symmetries ranging from conventional uniaxial\nnematic or anti-nematic to orthorhombic [Mundoor et al., Science 360, 768\n(2018)]. We provide a theoretical analysis of the elastic moduli of such\nsystems by considering interactions between the individual rods with the\nembedding solvent through surface-anchoring forces, as well as steric and\nelectrostatic interactions between the rods themselves. For uniaxial systems\nthe presence of colloidal rods generates a marked increase of the splay\nelasticity which we found to be in quantitative agreement with experimental\nmeasurements. For orthorhombic hybrid liquid crystals we provide estimates of\nall twelve elastic moduli and show that only a small subset of those elastic\nconstants play a relevant role in describing the nemato-elastic properties. The\ncomplexity and possibilities related to identifying the elastic moduli in\nexperiments are briefly discussed. The results are expected to be helpful in\nstimulating future studies on defect-dressed \"topological\" colloids and the\nanalysis of boundary-driven phenomena where the non-trivial director topology\ngenerated by biaxial nematics plays a key role."
    },
    {
        "anchor": "Melting of Polydisperse Hard Disks: The melting of a polydisperse hard disk system is investigated by Monte Carlo\nsimulations in the semigrand canonical ensemble. This is done in the context of\npossible continuous melting by a dislocation unbinding mechanism, as an\nextension of the 2D hard disk melting problem. We find that while there is\npronounced fractionation in polydispersity, the apparent density-polydispersity\ngap does not increase in width, contrary to 3D polydisperse hard spheres. The\npoint where the Young's modulus is low enough for the dislocation unbinding to\noccur moves with the apparent melting point, but stays within the density gap,\njust like for the monodisperse hard disk system. Additionally, we find that\nthroughout the accessible polydispersity range, the bound dislocation-pair\nconcentration is high enough to affect the dislocation unbinding melting as\npredicted by Kosterlitz, Thouless, Halperin, Nelson and Young.",
        "positive": "Hydrodynamics of Micro-swimmers in Films: One of the principal mechanisms by which surfaces and interfaces affect\nmicrobial life is by perturbing the hydrodynamic flows generated by swimming.\nBy summing a recursive series of image systems we derive a numerically\ntractable approximation to the three-dimensional flow fields of a Stokeslet\n(point force) within a viscous film between a parallel no-slip surface and\nno-shear interface and, from this Green's function, we compute the flows\nproduced by a force- and torque-free micro-swimmer. We also extend the exact\nsolution of Liron & Mochon (1976) to the film geometry, which demonstrates that\nthe image series gives a satisfactory approximation to the swimmer flow fields\nif the film is sufficiently thick compared to the swimmer size, and we derive\nthe swimmer flows in the thin-film limit. Concentrating on the thick film case,\nwe find that the dipole moment induces a bias towards swimmer accumulation at\nthe no-slip wall rather than the water-air interface, but that higher-order\nmultipole moments can oppose this. Based on the analytic predictions we propose\nan experimental method to find the multipole coefficient that induces circular\nswimming trajectories, allowing one to analytically determine the swimmer's\nthree-dimensional position under a microscope."
    },
    {
        "anchor": "Dynamics of microswimmers near a liquid-liquid interface with viscosity\n  difference: Transport of material across liquid interfaces is ubiquitous for living cells\nand is also a crucial step in drug delivery and in many industrial processes.\nThe fluids that are present on either side of the interfaces will usually have\ndifferent viscosities. We present a physical model for the dynamics of\nmicroswimmers near a soft and penetrable interface that we solve using computer\nsimulations of Navier-Stokes flows. The literature contains studies of similar\nisoviscous fluid systems, where the two fluids have the same viscosity. Here we\nextend this to the more general case where they have different viscosities. We\ninvestigate the effect of the fluid viscosity ratio on the movement patterns of\nmicroswimmers. We find that swimmers systematically reorientate towards the\nregion containing the lower viscosity fluid. Ultimately this is expected to\ndrive the swimmers to behave as if they are more inclined to swim in low\nviscosity fluids. Furthermore, in addition to the types of swimming already\nreported in the isoviscous system, i.e. bouncing, sliding and penetrating, we\nobserved a hovering motion, in which strong pullers swim parallel to the\ninterface with a certain distance, which is consistent with the dynamics of\nsuch swimmers near the solid wall.",
        "positive": "Generalized Stokes laws for active colloids and their applications: The force per unit area on the surface of a colloidal particle is a\nfundamental dynamical quantity in the mechanics and statistical mechanics of\ncolloidal suspensions. Here we compute it in the limit of slow viscous flow for\na suspension of $N$ spherical active colloids in which activity is represented\nby surface slip. Our result is best expressed as a set of linear relations, the\n\"generalized Stokes laws\", between the coefficients of a tensorial spherical\nharmonic expansion of the force per unit area and the surface slip. The\ngeneralized friction tensors in these laws are many-body functions of the\ncolloidal configuration and can be obtained to any desired accuracy by solving\na system of linear equations. Quantities derived from the force per unit area -\nforces, torques and stresslets on the colloids and flow, pressure and entropy\nproduction in the fluid - have succinct expressions in terms of the generalized\nStokes laws. Most notably, the active forces and torques have a dissipative,\nlong-ranged, many-body character that can cause phase separation,\ncrystallization, synchronization and a variety of other effects observed in\nactive suspensions. We use the results above to derive the Langevin and\nSmoluchowski equations for Brownian active suspensions, to compute active\ncontributions to the suspension stress and fluid pressure, and to relate the\nsynchrony in a lattice of harmonically trapped active colloids to entropy\nproduction. Our results provide the basis for a microscopic theory of active\nBrownian suspensions that consistently accounts for momentum conservation in\nthe bulk fluid and at fluid-solid boundaries"
    },
    {
        "anchor": "Density depletion and enhanced fluctuations in water near hydrophobic\n  solutes: identifying the underlying physics: We investigate the origin of the density depletion and enhanced density\nfluctuations that occur in water in the vicinity of an extended hydrophobic\nsolute. We argue that both phenomena are remnants of the critical drying\nsurface phase transition that occurs at liquid-vapor coexistence in the\nmacroscopic planar limit, ie. as the solute radius $R_s\\to\\infty$. Focusing on\nthe density profile $\\rho(r)$ and a sensitive spatial measure of fluctuations,\nthe local compressibility profile $\\chi(r)$, we develop a scaling theory which\nexpresses the extent of the density depletion and enhancement in\ncompressibility in terms of $R_s$, the strength of solute-water attraction\n$\\varepsilon_s$, and the deviation from liquid-vapor coexistence $\\delta\\mu$.\nTesting the predictions against results of classical density functional theory\nfor a simple solvent and Grand Canonical Monte Carlo simulations of a popular\nwater model, we find that the theory provides a firm physical basis for\nunderstanding how water behaves at a hydrophobe.",
        "positive": "Entropic Elasticity, Cooperative Extensibility and Supercoiling Property\n  of DNA: A Unified Viewpoint: A unified model is constructed to study the recently observed DNA entropic\nelasticity, cooperative extensibility, and supercoiling property. With the\nintroduction of a new structural parameter (the folding angle $\\phi$), bending\ndeformations of sugar-phosphate backbones, steric effects of nucleotide\nbasepairs, and short-range basestacking interactions are considered. The\ncomprehensive agreement of theoretical results with experimental observations\non both torsionally relaxed and negatively supercoiled DNAs strongly indicates\nthat, basestacking interactions, although short-ranged in nature, dominate the\nelasticity of DNA and hence are of vital biological significance."
    },
    {
        "anchor": "Effect of a Microscopic Roughness on Biological Adhesion of a Spherical\n  Capsule: By means of computer simulations, this work addresses adhesion of a\ndeformable spherical capsule to a micro-rough surface consisting of a periodic\narray of pillars. Depending on the micro-relief topography, three different\nadhesion regimes have been observed: 1) weak adhesion without deformation of\nthe membrane (fakir state); 2) strong adhesion with deformation of the capsule\nmembrane and binding to the bottom wall (nested or contacting state); 3)\nimpalement of the capsule by micropillars. It has been found that a periodic\nmicro-relief implies a favorable positioning of the capsule on rough surfaces.",
        "positive": "Assembly of hard spheres in a cylinder: a computational and experimental\n  study: Hard spheres are an important benchmark of our understanding of natural and\nsynthetic systems. In this work, colloidal experiments and Monte Carlo\nsimulations examine the equilibrium and out-of-equilibrium assembly of hard\nspheres of diameter $\\sigma$ within cylinders of diameter $\\sigma\\leq D\\leq\n2.82\\sigma$. Although in such a system phase transitions formally do not exist,\nmarked structural crossovers are observed. In simulations, we find that the\nresulting pressure-diameter structural diagram echoes the densest packing\nsequence obtained at infinite pressure in this range of $D$. We also observe\nthat the out-of-equilibrium self-assembly depends on the compression rate. Slow\ncompression approximates equilibrium results, while fast compression can skip\nintermediate structures. Crossovers for which no continuous line-slip exists\nare found to be dynamically unfavorable, which is the source of this\ndifference. Results from colloidal sedimentation experiments at high P\\'eclet\nnumber are found to be consistent with the results of fast compressions, as\nlong as appropriate boundary conditions are used. The similitude between\ncompression and sedimentation results suggests that the assembly pathway does\nnot here sensitively depend on the nature of the out-of-equilibrium dynamics."
    },
    {
        "anchor": "Quantitative evaluation of methods to analyze motion changes in\n  single-particle experiments: The analysis of live-cell single-molecule imaging experiments can reveal\nvaluable information about the heterogeneity of transport processes and\ninteractions between cell components. These characteristics are seen as motion\nchanges in the particle trajectories. Despite the existence of multiple\napproaches to carry out this type of analysis, no objective assessment of these\nmethods has been performed so far. Here, we have designed a competition to\ncharacterize and rank the performance of these methods when analyzing the\ndynamic behavior of single molecules. To run this competition, we have\nimplemented a software library to simulate realistic data corresponding to\nwidespread diffusion and interaction models, both in the form of trajectories\nand videos obtained in typical experimental conditions. The competition will\nconstitute the first assessment of these methods, provide insights into the\ncurrent limits of the field, foster the development of new approaches, and\nguide researchers to identify optimal tools for analyzing their experiments.",
        "positive": "Microfluidics: The no-slip boundary condition: The no-slip boundary condition at a solid-liquid interface is at the center\nof our understanding of fluid mechanics. However, this condition is an\nassumption that cannot be derived from first principles and could, in theory,\nbe violated. We present a review of recent experimental, numerical and\ntheoretical investigations on the subject. The physical picture that emerges is\nthat of a complex behavior at a liquid/solid interface, involving an interplay\nof many physico-chemical parameters, including wetting, shear rate, pressure,\nsurface charge, surface roughness, impurities and dissolved gas."
    },
    {
        "anchor": "X-ray scattering characterization of iron oxide nanoparticles Langmuir\n  film on water surface and on a solid substrate: In the present study we compare a structure of a Langmuir film assembled from\nmagnetic iron oxide nanoparticles on water surface and a structure of the same\nfilm after its transfer to a solid substrate by the Langmuir-Schaefer method.\nIn contrast to most of related studies, where different techniques are used to\ncharacterize the films before and after the deposition, we use the same\ncombination of X-ray reflectometry and Grazing Incidence Small-Angle X-ray\nscattering. In both cases -- on a liquid and on a solid substrate -- the film\nwas identified as a well-ordered monolayer of the nanoparticles laterally\norganized in a two-dimensional hexagonal lattice. However parameters of the\nlattice were found to be slightly different depending on the type of the\nsubstrate. It is also demonstrated that Langmuir-Schaefer technique is the\nright way for deposition of such kind of the particles on a solid substrate.",
        "positive": "Coupling between aging and convective motion in a colloidal glass of\n  Laponite: We study thermal convection in a colloidal glass of Laponite in formation.\nLow concentration preparation are submitted to destabilizing vertical\ntemperature gradient, and present a gradual transition from a turbulent\nconvective state to a steady conductive state as their viscosity increases. The\ntime spent under convection is found to depend strongly on sample\nconcentration, decreasing exponentially with mass fraction of colloidal\nparticles. Moreover, at fixed concentration, it also depends slightly on the\npattern selected by the Rayleigh B\\'{e}nard instability: more rolls maintain\nthe convection state longer. This behavior can be interpreted with recent\ntheoretical approaches of soft glassy material rheology."
    },
    {
        "anchor": "Design of nanoparticles for generation and stabilization of CO2-in-brine\n  foams with or without added surfactants: Whereas many studies have examined stabilization of emulsions and foams in\nlow salinity aqueous phases with nanoparticles (NPs) with and without added\nsurfactants, interest has grown recently in much higher salinities relevant to\nsubsurface oil and gas applications. It is shown for the first time that NPs\ngrafted with well-defined low molecular weight ligands colloidally stable in\nconcentrated brine (in particular, API brine, 8% NaCl + 2% CaCl2) and are\ninterfacially active at the brine-air interface. These properties were achieved\nfor three types of ligands: a nonionic diol called GLYMO and two short\npoly(ethylene glycol) (PEG) oligomers with 6-12 EO repeat units. Carbon\ndioxide-in-water (C/W) foams could be formed only with modified NPs with higher\nsurface pressures at the A/W interface. Furthermore, these ligands were\nsufficiently CO2-philic that the hydrophilic/CO2-philic balance of silica NPs\nwas low enough for stabilization of CO2-in-water (C/W) foam with API brine.\nAdditionally, NPs with these three ligands formed stable dispersions with\nvarious free molecular surfactants in DI water and even API brine (8% NaCl + 2%\nCaCl2) at room temperature. A wide variety of mixtures of NPs plus anionic,\nnonionic, or cationic mixtures that formed stable dispersions were also found\nto stabilize C/W foams in porous media at high salinity. These results provide\na basis for future studies of the mechanism of foam stabilization with NPs and\nNP/surfactant mixtures at high salinity.",
        "positive": "Flexible Linear Polyelectrolytes in Multivalent Salt Solutions:\n  Solubility Conditions: Polyelectrolytes such as single and double stranded DNA and many synthetic\npolymers undergo two structural transitions upon increasing the concentration\nof multivalent salt or molecules. First, the expanded-stretched chains in low\nmonovalent salt solutions collapse into nearly neutral compact structures when\nthe density of multivalent salt approaches that of the monomers. With further\naddition of multivalent salt the chains redissolve acquiring expanded-coiled\nconformations. We study the redissolution transition using a two state model\n[F. Solis and M. Olvera de la Cruz, {\\it J. Chem. Phys.} {\\bf 112} (2000)\n2030]. The redissolution occurs when there is a high degree of screening of the\nelectrostatic interactions between monomers, thus reducing the energy of the\nexpanded state. The transition is determined by the chemical potential of the\nmultivalent ions in the solution $\\mu$ and the inverse screening length\n$\\kappa$. The transition point also depends on the charge distribution along\nthe chain but is almost independent of the molecular weight and degree of\nflexibility of the polyelectrolytes. We generate a diagram of $\\mu$ versus\n$\\kappa^2$ where we find two regions of expanded conformations, one with\ncharged chains and other with overcharged (inverted charge) chains, separated\nby a collapsed nearly neutral conformation region. The collapse and\nredissolution transitions occur when the trajectory of the properties of the\nsalt crosses the boundaries between these regions. We find that in most cases\nthe redissolution occurs within the same expanded branch from which the chain\nprecipitates."
    },
    {
        "anchor": "Shear instability in skin tissue: We propose two toy-models to describe, predict, and interpret the wrinkles\nappearing on the surface of skin when it is sheared. With the first model, we\naccount for the lines of greatest tension present in human skin by subjecting a\nlayer of soft tissue to a pre-stretch, and for the epidermis by endowing one of\nthe layer's faces with a surface tension. For the second model, we consider an\nanisotropic model for the skin, to reflect the presence of stiff collagen\nfibres in a softer elastic matrix. In both cases, we find an explicit\nbifurcation criterion, linking geometrical and material parameters to a\ncritical shear deformation accompanied by small static wrinkles, with decaying\namplitudes normal to the free surface of skin.",
        "positive": "Elementary Excitation Modes in a Granular Glass above Jamming: The dynamics of granular media in the jammed, glassy region is described in\nterms of \"modes\", by applying a Principal Component Analysis (PCA) to the\ncovariance matrix of the position of individual grains. We first demonstrate\nthat this description is justified and gives sensible results in a regime of\ntime/densities such that a metastable state can be observed on long enough\ntimescale to define the reference configuration. For small enough times/system\nsizes, or at high enough packing fractions, the spectral properties of the\ncovariance matrix reveals large, collective fluctuation modes that cannot be\nexplained by a Random Matrix benchmark where these correlations are discarded.\nWe then present a first attempt to find a link between the softest modes of the\ncovariance matrix during a certain \"quiet\" time interval and the spatial\nstructure of the rearrangement event that ends this quiet period. The motion\nduring these cracks is indeed well explained by the soft modes of the dynamics\nbefore the crack, but the number of cracks preceded by a \"quiet\" period\nstrongly reduces when the system unjams, questioning the relevance of a\ndescription in terms of modes close to the jamming transition, at least for\nfrictional grains."
    },
    {
        "anchor": "Formation of polymer brushes: In systems such as block copolymer mesophases or physical gels formed by\nassociating copolymers, the dynamical properties are often controlled by the\nextraction/association of a sticking group. We propose a description of the\nextraction/association process of a single sticker. The statistical physics of\nthese associated systems is usually dominated by stretched brush-like regions.\nA sticker has to overcome a potential barrier both to penetrate the stretched\nstructure or to escape a favorable region built by associated stickers. Our\nmain result is that these barriers are crossed by tension fluctuations and that\nthe corresponding processes are thus local with a friction independent of\nmolecular weight. When the potential barriers are high, the (very stretched)\nequilibrium structures are not likely to develop on reasonable time scales.\nStretched model systems may also be grown in situ from nuclei bearing\ninitiating groups. These, irreversibly bound structures, are also briefly\ndiscussed.",
        "positive": "From ultra-fast growth to avalanche growth in devitrifying glasses: During devitrification, pre-existing crystallites grow by adding particles to\ntheir surface via a process that is either thermally activated (diffusive mode)\nor happens without kinetic barriers (fast crystal growth mode). It is yet\nunclear what factors determine the crystal growth mode and how to predict it.\nWith simulations of repulsive hard-sphere-like (Weeks-Chandler-Andersen)\nglasses, we show for the first time that the same system at the same volume\nfraction and temperature can devitrify via both modes depending on the\npreparation protocol of the glass. We prepare two types of glass, a\nconventional glass (CG) via fast quenching and a uniform glass (UG) via density\nhomogenization. Firstly, we bring either glass into contact with a crystal (X)\nand find the inherent structure (CGX/UGX). During energy minimization, the\ncrystal front grows deep into the CG interface, while the growth is minimal for\nUG. When thermal noise is added, this behavior is reflected in different\ncrystallization dynamics. CGX exhibits a density drop at the crystal growth\nfront which correlates with enhanced dynamics at the interface and a fast\ngrowth mode. This mechanism may explain the faster crystal growth observed\nbelow the glass transition experimentally. In contrast, UGX grows via\nintermittent avalanche-like dynamics localized at the interface, a combination\nof localized mechanical defects and the exceptional mechanical stability\nimposed by the UG glass phase."
    },
    {
        "anchor": "Observation of anomalous spin-state segregation in a trapped ultra-cold\n  vapor: We observe counter-intuitive spin segregation in an inhomogeneous sample of\nultra-cold, non-condensed Rubidium atoms in a magnetic trap. We use spatially\nselective microwave spectroscopy to verify a model that accounts for the\ndifferential forces on two internal spin states. In any simple understanding of\nthe cloud dynamics, the forces are far too small to account for the dramatic\ntransient spin polarizations observed. The underlying mechanism remains to be\nelucidated.",
        "positive": "Dynamics of a bubble formed in double stranded DNA: We study the fluctuational dynamics of a tagged base-pair in double stranded\nDNA. We calculate the drift force which acts on the tagged base-pair using a\npotential model that describes interactions at base pairs level and use it to\nconstruct a Fokker-Planck equation.The calculated displacement autocorrelation\nfunction is found to be in very good agreement with the experimental result of\nAltan-Bonnet {\\it et. al.} Phys. Rev. Lett. {\\bf 90}, 138101 (2003) over the\nentire time range of measurement. We calculate the most probable displacements\nwhich predominately contribute to the autocorrelation function and the\nhalf-time history of these displacements."
    },
    {
        "anchor": "Condensate fraction of molecules for a spin mixture of ultracold\n  fermionic atoms: The condensate fraction of molecules for ultracold Fermi gases is\ninvestigated for the magnetic field below the Feshbach resonant magnetic field.\nAssuming that there is no loss of particles and energy during the adiabatic\nmagnetic-field sweep, a simple theory is used to interpret the measured\ncondensate fraction in the experiments by JILA group (Phys. Rev. Lett. 92,\n040403 (2004)) and MIT group (Phys. Rev. Lett. 92, 120403 (2004)). Our theory\nshows that the condensate fraction of molecules is dependent on the initial\ncondition of the system and especially on the process of the magnetic-field\nsweep.",
        "positive": "Covariant description of the colloidal dynamics on curved manifolds: Brownian motion is a universal characteristic of colloidal particles embedded\nin a host medium, and it is the fingerprint of molecular transport or\ndiffusion, a generic feature of relevance not only in Physics but also in\nseveral branches of Science and Engineering. Since its discovery, Brownian\nmotion or colloid dynamics has been important in elucidating the connection\nbetween the molecular details of the diffusing macromolecule and the\nmacroscopic information of the host medium. However, colloid dynamics is far\nfrom being completely understood. For example, the diffusion of non-spherical\ncolloids and the effects of geometry on the dynamics of either passive or\nactive colloids are a few representative cases that are part of the current\nchallenges in Soft Matter Physics. In this contribution, we take a step forward\nto introduce a covariant description of the colloid dynamics in curved spaces.\nThis formalism will allow us to understand several phenomena, for instance, the\neffects of curvature on the kinetics during spinodal decomposition and the\nthermodynamic properties of the colloidal dispersion, just to mention a few\nexamples. This theoretical framework will also serve as the starting point to\nhighlight the role of geometry on colloid dynamics, an aspect that is of\nparamount importance to understanding more complex phenomena, such as the\ndiffusive mechanisms of proteins embedded in cell membranes."
    },
    {
        "anchor": "Time reversal sub-wavelength focusing in bubbly media: Thanks to a Multiple Scattering Theory algorithm, we present a way to focus\nenergy at the deep subwavelength scale, from the far-field, inside a cubic\ndisordered bubble cloud by using broadband Time Reversal (TR). We show that the\nanalytical calculation of an effective wavenumber performing the Independant\nScattering Approximation (ISA) matches the numerical results for the focal\nextension. Subwavelength focusings of lambda/100 are reported for simulations\nwith perfect bubbles (no loss). A more realistic case, with viscous and thermal\nlosses, allows us to obtain a $\\lambda/14$ focal spot, with a low volume\nfraction of scatterers (phi = 0.01). Bubbly materials could open new\nperspective for acoustic actuation in the microfluidic context.",
        "positive": "Simple Model of Sickle Hemogloblin: A microscopic model is proposed for the interactions between sickle\nhemoglobin molecules based on information from the protein data bank. A Monte\nCarlo simulation of a simplified two patch model is carried out, with the goal\nof understanding fiber formation. A gradual transition from monomers to one\ndimensional chains is observed as one varies the density of molecules at fixed\ntemperature, somewhat similar to the transition from monomers to polymer fibers\nin sickle hemoglobin molecules in solution. An observed competition between\nchain formation and crystallization for the model is also discussed. The\nresults of the simulation of the equation of state are shown to be in excellent\nagreement with a theory for a model of globular proteins, for the case of two\ninteracting sites."
    },
    {
        "anchor": "A new bond fluctuation method for a polymer undergoing gel\n  electrophoresis: We present a new computational methodology for the investigation of gel\nelectrophoresis of polyelectrolytes. We have developed the method initially to\nincorporate sliding motion of tight parts of a polymer pulled by an electric\nfield into the bond fluctuation method (BFM). Such motion due to tensile force\nover distances much larger than the persistent length is realized by non-local\nmovement of a slack monomer at an either end of the tight part. The latter\nmovement is introduced stochastically. This new BFM overcomes the well-known\ndifficulty in the conventional BFM that polymers are trapped by gel fibers in\nrelatively large fields. At the same time it also reproduces properly\nequilibrium properties of a polymer in a vanishing filed limit. The new BFM\nthus turns out an efficient computational method to study gel electrophoresis\nin a wide range of the electric field strength.",
        "positive": "Tuning Pairwise Potential Can Control the Fragility of Glass-Forming\n  Liquids: From Tetrahedral Network to Isotropic Soft Sphere Models: We perform molecular dynamics simulations for a silica glass former model\nproposed by Coslovich and Pastore (CP) over a wide range of densities. The\ndensity variation can be mapped onto the change of the potential depth between\nSi and O interactions of the CP model. By reducing the potential depth (or\nincreasing the density), the anisotropic tetrahedral network structure observed\nin the original CP model transforms into the isotropic structure with the\npurely repulsive soft-sphere potential. Correspondingly, the temperature\ndependence of the relaxation time exhibits the crossover from the Arrhenius to\nthe super-Arrhenius behavior. Being able to control the fragility over a wide\nrange by tuning the potential of a single model system helps us to bridge the\ngap between the network and isotropic glass formers and to obtain the insight\ninto the underlying mechanism of the fragility. We study the relationship\nbetween the fragility and dynamical properties such as the magnitude of the\nStokes-Einstein violation and the stretch exponent in the density correlation\nfunction. We also demonstrate that the peak of the specific heat systematically\nshifts as the density increases, hinting that the fragility is correlated with\nthe hidden thermodynamic anomalies of the system."
    },
    {
        "anchor": "Hydrodynamics of shape-driven rigidity transitions in motile tissues: In biological tissues, it is now well-understood that mechanical cues are a\npowerful mechanism for pattern regulation. While much work has focused on\ninteractions between cells and external substrates, recent experiments suggest\nthat cell polarization and motility might be governed by the internal shear\nstiffness of nearby tissue, deemed \"plithotaxis\". Meanwhile, other work has\ndemonstrated that there is a direct relationship between cell shapes and tissue\nshear modulus in confluent tissues. Joining these two ideas, we develop a\nhydrodynamic model that couples cell shape, and therefore tissue stiffness, to\ncell motility and polarization. Using linear stability analysis and numerical\nsimulations, we find that tissue behavior can be tuned between largely\nhomogeneous states and patterned states such as asters, controlled by a\ncomposite \"morphotaxis\" parameter that encapsulates the nature of the coupling\nbetween shape and polarization. The control parameter is in principle\nexperimentally accessible, and depends both on whether a cell tends to move in\nthe direction of lower or higher shear modulus, and whether sinks or sources of\npolarization tend to fluidize the system.",
        "positive": "Dynamics of the peel front and the nature of acoustic emission during\n  peeling of an adhesive tape: We investigate the peel front dynamics and acoustic emission of an adhesive\ntape within the context of a recent model by including an additional\ndissipative energy that mimics bursts of acoustic signals. We find that the\nnature of the peeling front can vary from smooth to stuck-peeled configuration\ndepending on the values of dissipation coefficient, inertia of the roller, mass\nof the tape. Interestingly, we find that the distribution of AE bursts shows a\npower law statistics with two scaling regimes with increasing pull velocity as\nobserved in experiments. In this regimes, the stuck-peeled configuration is\nsimilar to the `edge of peeling' reminiscent of a system driven to a critical\nstate."
    },
    {
        "anchor": "The potential energy states and mechanical properties of thermally\n  cycled binary glasses: The influence of repeated thermal cycling on mechanical properties,\nstructural relaxation, and evolution of the potential energy in binary glasses\nis investigated using molecular dynamics simulations. We consider a binary\nmixture with strongly non-additive cross interactions, which is annealed across\nthe glass transition with different cooling rates and then exposed to one\nthousand thermal cycles at constant pressure. We found that during the first\nfew hundred transient cycles, the potential energy minima after eachcycle\ngradually decrease and the structural relaxation proceeds via collective,\nirreversible displacements of atoms. With increasing cycle number, the\namplitudes of the volume and potential energy oscillations are significantly\nreduced, and the potential energy minima saturate to a constant value that\ndepends on the thermal amplitude and cooling rate. In the steady state, the\nglasses thermally expand and contract but most of the atoms return to\ntheircages after each cycle, similar to limit cycles found in periodically\ndriven amorphous materials. The results of tensile tests demonstrate that the\nelastic modulus and the yielding peak, evaluated after the thermal treatment,\nacquire maximum values at a particular thermal amplitude, which coincides with\nthe minimum of the potential energy.",
        "positive": "Shear Flows and Shear Viscosity in a Two-Dimensional Yukawa System\n  (Dusty Plasma): The shear viscosity of a two-dimensional liquid-state dusty plasma was\nmeasured experimentally. A monolayer of highly charged polymer microspheres,\nwith a Yukawa interaction, was suspended in a plasma sheath. Two\ncounter-propagating Ar laser beams pushed the particles, causing shear-induced\nmelting of the monolayer and a shear flow in a planar Couette configuration. By\nfitting the particle velocity profiles in the shear flow to a Navier-Stokes\nmodel, the kinematic viscosity was calculated; it was of order 1 mm^2/s,\ndepending on the monolayer's parameters and shear stress applied."
    },
    {
        "anchor": "Nematic liquid crystal boojums with handles on colloidal handlebodies: Topological defects that form on surfaces of ordered media, dubbed boojums,\nare ubiquitous in superfluids, liquid crystals (LCs), Langmuir monolayers, and\nBose-Einstein condensates. They determine supercurrents in superfluids, impinge\non electrooptical switching in polymer-dispersed LCs, and mediate chemical\nresponse at nematic-isotropic fluid interfaces, but the role of surface\ntopology in the appearance, stability, and core structure of these defects\nremains poorly understood. Here, we demonstrate robust generation of boojums by\ncontrolling surface topology of colloidal particles that impose tangential\nboundary conditions for the alignment of LC molecules. To do this, we design\nhandlebody-shaped polymer particles with different genus g. When introduced\ninto a nematic LC, these particles distort the nematic molecular alignment\nfield while obeying topological constraints and induce at least 2g - 2 boojums\nthat allow for topological charge conservation. We characterize 3D textures of\nboojums using polarized nonlinear optical imaging of molecular alignment and\nexplain our findings by invoking symmetry considerations and numerical modeling\nof experiment-matching director fields, order parameter variations, and\nnontrivial handle-shaped core structure of defects. Finally, we discuss how\nthis interplay between the topologies of colloidal surfaces and boojums may\nlead to controlled self-assembly of colloidal particles in nematic and\nparanematic hosts, which, in turn, may enable reconfigurable topological\ncomposites.",
        "positive": "Spontaneous Lipid Binding to the Nicotinic Acetylcholine Receptor in a\n  Native Membrane: The nicotinic acetylcholine receptor (nAChR) and other pentameric\nligand-gated ion channels (pLGICs) are native to neuronal membranes with an\nunusual lipid composition. While it is well-established that these receptors\ncan be significantly modulated by lipids, the underlying mechanisms have been\nprimarily studied in model membranes with only a few lipid species. Here we use\ncoarse-grained molecular dynamics (MD) simulation to probe specific binding of\nlipids in a complex quasi-neuronal membrane. We ran a total of 50 microseconds\nof simulations of a single nAChR in a membrane composed of 36 species of\nlipids. Competition between multiple lipid species produces a complex\ndistribution. We find that overall, cholesterol selects for concave\nintersubunit sites and PUFAs select for convex M4 sites, while monounsaturated\nand saturated lipids are unenriched in the nAChR boundary. In order to\ncharacterize binding to specific sites, we present a novel approach for\ncalculating a \"density-threshold affinity\" from continuous density\ndistributions. We find that affinity for M4 weakens with chain rigidity, which\nsuggests flexible chains may help relax packing defects caused by the conical\nprotein shape. For any site, PE headgroups have the strongest affinity of all\nphospholipid headgroups, but anionic lipids still yield moderately high\naffinities for the M4 sites as expected. We observe cooperative effects between\nanionic headgroups and saturated chains at the M4 site in the inner leaflet. We\nalso analyze affinities for individual anionic headgroups. Combined, these\ninsights may reconcile several apparently contradictory experiments on the role\nof anionic phospholipids in modulating nAChR."
    },
    {
        "anchor": "Inertial Effects on the Stress Generation of Active Fluids: Suspensions of self-propelled bodies generate a unique mechanical stress\nowing to their motility that impacts their large-scale collective behavior. For\nmicroswimmers suspended in a fluid with negligible particle inertia, we have\nshown that the virial `swim stress' is a useful quantity to understand the\nrheology and nonequilibrium behaviors of active soft matter systems. For larger\nself-propelled organisms like fish, it is unclear how particle inertia impacts\ntheir stress generation and collective movement. Here, we analyze the effects\nof finite particle inertia on the mechanical pressure (or stress) generated by\na suspension of self-propelled bodies. We find that swimmers of all scales\ngenerate a unique `swim stress' and `Reynolds stress' that impacts their\ncollective motion. We discover that particle inertia plays a similar role as\nconfinement in overdamped active Brownian systems, where the reduced run length\nof the swimmers decreases the swim stress and affects the phase behavior.\nAlthough the swim and Reynolds stresses vary individually with the magnitude of\nparticle inertia, the sum of the two contributions is independent of particle\ninertia. This points to an important concept when computing stresses in\ncomputer simulations of nonequilibrium systems---the Reynolds and the virial\nstresses must both be calculated to obtain the overall stress generated by a\nsystem.",
        "positive": "Re-defining the concept of hydration water in water under soft\n  confinement: Water shapes and defines the properties of biological systems. Therefore,\nunderstanding the nature of the mutual interaction between water and biological\nsystems is of primary importance for a proper assessment of biological activity\nand the development of new drugs and vaccines. A handy way to characterize the\ninteractions between biological systems and water is to analyze their impact on\nwater density and dynamics in the proximity of the interfaces. It is well\nestablished that water bulk density and dynamical properties are recovered at\ndistances in the order of $\\sim1$~nm from the surface of biological systems.\nSuch evidence led to the definition of \\emph{hydration} water as the thin layer\nof water covering the surface of biological systems and affecting-defining\ntheir properties and functionality. Here, we review some of our latest\ncontributions showing that phospholipid membranes affect the structural\nproperties and the hydrogen bond network of water at greater distances than the\ncommonly evoked $\\sim1$~nm from the membrane surface. Our results imply that\nthe concept of hydration water should be revised or extended, and pave the way\nto a deeper understanding of the mutual interactions between water and\nbiological systems."
    },
    {
        "anchor": "Rotating hematite cube chains: Recently a two-dimensional chiral fluid was experimentally demonstrated. It\nwas obtained from cubic-shaped hematite colloidal particles placed in a\nrotating magnetic field. Here we look at building blocks of that fluid, by\nanalyzing short hematite chain behavior in a rotating magnetic field. We find\nequilibrium structures of chains in static magnetic fields and observe chain\ndynamics in rotating magnetic fields. We find and experimentally verify that\nthere are three planar motion regimes and one where the cube chain goes out of\nthe plane of the rotating magnetic field. In this regime we observe interesting\ndynamics -- the chain rotates slower than the rotating magnetic field. In order\nto catch up with the magnetic field, it rolls on an edge and through rotation\nin the third dimension catches up with the magnetic field. The same dynamics is\nalso observable for a single cube when gravitational effects are explicitly\ntaken into account.",
        "positive": "MC-DEM: a novel simulation scheme for modeling dense granular media: This article presents a new force model for performing quantitative\nsimulations of dense granular materials. Interactions between multiple contacts\n(MC) on the same grain are explicitly taken into account. Our readily\napplicable method retains all the advantages of discrete element method (DEM)\nsimulations and does not require the use of costly finite element methods. The\nnew model closely reproduces our recent experimental measurements, including\ncontact force distributions in full 3D, at all compression levels up to the\nexperimental maximum limit of 13\\%. Comparisons with traditional non-deformable\nspheres approach are provided, as well as with alternative models for\ninteractions between multiple contacts. The success of our model compared to\nthese alternatives demonstrates that interactions between multiple contacts on\neach grain must be included for dense granular packings."
    },
    {
        "anchor": "Charge polarization, local electroneutrality breakdown and eddy\n  formation due to electroosmosis in varying-section channels: We characterize the dynamics of an electrolyte embedded in a varying-section\nchannel under the action of a constant external electrostatic field. By means\nof molecular dynamics simulations we determine the stationary density, charge\nand velocity profiles of the electrolyte. Our results show that when the Debye\nlength is comparable to the width of the channel bottlenecks a concentration\npolarization along with two eddies sets inside the channel. Interestingly, upon\nincreasing the external field, local electroneutrality breaks down and charge\npolarization sets leading to the onset of net dipolar field. This novel\nscenario, that cannot be captured by the standard approaches based on local\nelectroneutrality, opens the route for the realization of novel micro and\nnano-fluidic devices.",
        "positive": "Numerical modeling of optical modes in topological soft matter: Vector and vortex laser beams are desired in many applications and are\nusually created by manipulating the laser output or by inserting optical\ncomponents in the laser cavity. Distinctly, inserting liquid crystals into the\nlaser cavity allows for extensive control over the emitted light due to their\nhigh susceptibility to external fields and birefringent nature. In this work we\ndemonstrate diverse optical modes for lasing as enabled and stablised by\ntopological birefringent soft matter structures using numerical modelling. We\nshow diverse structuring of light -- with different 3D intensity and\npolarization profiles -- as realised by topological soft matter structures in\nradial nematic droplet, in 2D nematic cavities of different geometry and\nincluding topological defects with different charges and winding numbers, in\narbitrary varying birefringence fields with topological defects and in\npixelated birefringent profiles. We use custom written FDFD code to calculate\nemergent electromagnetic eigenmodes. Control over lasing is of a particular\ninterest aiming towards the creation of general intensity, polarization and\ntopologically shaped laser beams."
    },
    {
        "anchor": "Manning condensation in two dimensions: We consider a macroion confined to a cylindrical cell and neutralized by\noppositely charged counterions. Exact results are obtained for the\ntwo-dimensional version of this problem, in which ion-ion and ion-macroion\ninteractions are logarithmic. In particular, the threshold for counterion\ncondensation is found to be the same as predicted by mean-field theory. With\nfurther increase of the macroion charge, a series of single-ion condensation\ntransitions takes place. Our analytical results are expected to be exact in the\nvicinity of these transitions and are in very good agreement with recent\nMonte-Carlo simulation data.",
        "positive": "Mixing and de-mixing of model microswimmers in bi-motility mixtures: Cooperation between micro-organisms give rise to novel phenomena like\nclustering, swarming in suspension. We study the collective behavior of the\nartificial swimmer called Taylor line at low Reynolds number using\nmulti-particle collision dynamics method. In this paper we have modeled\nbi-motility mixtures of multiple swimmers in 2 dimensions, which differ from\neach other by the velocity with which they swim. We observe that the swimmers\ncan segregate into slower and faster ones depending on the relative difference\nin velocity of the 2 type of swimmers. We also observe that contribution of\nslower swimmers towards clustering, on an average, is much larger compared to\nfaster ones, although we employ a homogeneous mixture. When the difference in\nvelocity is large between the swimmers, the faster ones move away from the\nslower ones towards the boundary. On the other hand, when the relative\ndifference in velocity is very small, the slower and faster swimmer mix\ntogether to form big clusters. At later time even for small difference in\nvelocity the swimmers segregate into fast and slow swimmer clusters."
    },
    {
        "anchor": "Phase Field Crystal model for particles with n-fold rotational symmetry\n  in two dimensions: We introduce a Phase Field Crystal (PFC) model for particles with n-fold\nrotational symmetry in two dimensions. Our approach is based on a free energy\nfunctional that depends on the reduced one-particle density, the strength of\nthe orientation, and the direction of the orientation, where all these order\nparameters depend on the position. The functional is constructed such that for\nparticles with axial symmetry (i. e. n = 2) the PFC model for liquid crystals\nas introduced by H. L\\\"owen [J. Phys.: Condens. Matter 22, 364105 (2010)] is\nrecovered. We discuss the stability of the functional and explore phases that\noccur for $1 \\leq n \\leq 6$. In addition to isotropic, nematic, stripe, and\ntriangular order, we also observe cluster crystals with square, rhombic,\nhoneycomb, and even quasicrystalline symmetry. The n-fold symmetry of the\nparticles corresponds to the one that can be realized for colloids with\nsymmetrically arranged patches. We explain how both, repulsive as well as\nattractive patches, are described in our model.",
        "positive": "A Two-Player Game of Life: We present a new extension of Conway's game of life for two players, which we\ncall p2life. P2life allows one of two types of token, black or white, to\ninhabit a cell, and adds competitive elements into the birth and survival rules\nof the original game. We solve the mean-field equation for p2life and determine\nby simulation that the asymptotic density of p2life approaches 0.0362."
    },
    {
        "anchor": "Water diffusion in carbon nanotubes for rigid and flexible models: We compared the diffusion of water confined in armchair and zigzag carbon\nnanotubes for rigid and flexible water models. Using one rigid model,\nTIP4P/2005, and two flexible models, SPC/Fw and SPC/FH, we found that the\nnumber of the number of hydrogen bonds that water forms depends on the\nstructure of the nanotube, directly affecting the diffusion of water. The\nsimulation results reveal that due to the hydrophobic nature of carbon\nnanotubes and the degrees of freedom imposed by the water force fields, water\nmolecules tend to avoid the surface of the carbon nanotube. This junction of\nvariables plays a central role in the diffusion of water, mainly in narrow\nand/or deformed nanotubes, governing the mobility of confined water in a\nnon-trivial way, where the greater the degree of freedom of the water force\nfield, the smaller it will be mobility in confinement, as we limit the\ncompetition between area/volume, and it no longer plays the unique role in\nchanging water diffusivity.",
        "positive": "C-S-H gel densification: the impact of the nanoscale on self desiccation\n  and sorption isotherms: The relationship between humidity and water content in a hydrating cement\npaste is largely controlled by the nanostructure of the C-S-H gel. Current\nhydration models do not describe this nanostructure, thus sorption isotherms\nand self-desiccation are given as constitutive inputs instead of being\npredicted from microstructural evolution. To address this limitation, this work\ncombines a C-S-H gel description from nanoscale simulations with evolving\ncapillary pore size distributions from a simple hydration model. Results show\nthat a progressive densification of the C-S-H gel must be considered in order\nto explain the self-desiccation of low-alkali pastes. The impact of C-S-H\ndensification on the evolution of microstructure and sorption isotherms is then\ndiscussed, including the effect of water-to-cement ratio, cement powder\nfineness, and curing temperature. Overall, this work identifies an area where\nnanoscale simulations can integrate larger-scale models of cement hydration and\nporomechanics."
    },
    {
        "anchor": "Dynamical theory of topological defects II: Universal aspects of defect\n  motion: We study the dynamics of topological defects in continuum theories governed\nby a free energy minimization principle, building on our recently developed\nframework [Romano J, Mahault B and Golestanian R 2023 J. Stat. Mech.: Theory\nExp. 083211]. We show how the equation of motion of point defects, domain\nwalls, disclination lines and any other singularity can be understood with one\nunifying mathematical framework. For disclination lines, this also allows us to\nstudy the interplay between the internal line tension and the interaction with\nother lines. This interplay is non-trivial, allowing defect loops to expand,\ninstead of contracting, due to external interaction. We also use this framework\nto obtain an analytical description of two long-lasting problems in point\ndefect motion, namely the scale dependence of the defect mobility and the role\nof elastic anisotropy in the motion of defects in liquid crystals. For the\nformer, we show that the effective defect mobility is strongly\nproblem-dependent, but it can be computed with high accuracy for a pair of\nannihilating defects. For the latter, we show that at the first order in\nperturbation theory, anisotropy causes a non-radial force, making the\ntrajectory of annihilating defects deviate from a straight line. At higher\norders, it also induces a correction in the mobility, which becomes\nnon-isotropic for the $+1/2$ defect. We argue that, due to its generality, our\nmethod can help to shed light on the motion of singularities in many different\nsystems, including driven and active non-equilibrium theories.",
        "positive": "Dynamic Clustering in Suspension of Motile Bacteria: Bacteria suspension exhibits a wide range of collective phenomena arising\nfrom interactions between individual cells. Here we show Serratia marcescens\ncells near an air-liquid interface spontaneously aggregate into dynamic\nclusters through surface-mediated hydrodynamic interactions. These long-lived\nclusters translate randomly and rotate in the counter-clockwise direction; they\ncontinuously evolve, merge with others and split into smaller ones.\nMeasurements indicate that long-ranged hydrodynamic interactions have strong\ninfluences on cluster properties. Bacterial clusters change material and fluid\ntransport near the interface and hence may have environmental and biological\nconsequences."
    },
    {
        "anchor": "Polymer translocation induced by adsorption: We study the translocation of a flexible polymer through a pore in a membrane\ninduced by its adsorption on \\trans side of the membrane. When temperature $T$\nis higher than $T_c$, the adsorption-desorption transition temperature,\nattractive interaction between polymer and membrane plays little role in\naffecting polymer conformation, leading to translocation time that scales as\n$\\tau\\sim L^3$ where $L$ is the polymer contour length. When $T < T_c$,\nhowever, the translocation time undergoes a sharp crossover to $\\tau\\sim L^2$\nfor sufficiently long polymers, following the second order conformational\n(adsorption) transition. The translocation time is found to exhibit the\ncrossover around $T=T_c'$, which is lower than $T_c$ for polymers shorter than\na critical length($N<N_c$).",
        "positive": "Classical density-functional theory of inhomogeneous water including\n  explicit molecular structure and nonlinear dielectric response: We present an accurate free-energy functional for liquid water written in\nterms of a set of effective potential fields in which fictitious noninteracting\nwater molecules move. The functional contains an \\emph{exact} expression of the\nentropy of noninteracting molecules and thus provides an ideal starting point\nfor the inclusion of complex inter-molecular interactions which depend on the\n\\emph{orientation} of the interacting molecules. We show how an excess\nfree-energy functional can be constructed to reproduce the following properties\nof water: the dielectric response; the experimental site-site correlation\nfunctions; the surface tension; the bulk modulus of the liquid and the\nvariation of this modulus with pressure; the density of the liquid and the\nvapor phase; and liquid-vapor coexistence. As a demonstration, we present\nresults for the application of this theory to the behavior of liquid water in a\nparallel plate capacitor. In particular, we make predictions for the dielectric\nresponse of water in the nonlinear regime, finding excellent agreement with\nknown data."
    },
    {
        "anchor": "Dynamics of a microorganism moving by chemotaxis in its own secretion: The Brownian dynamics of a single microorganism coupled by chemotaxis to a\ndiffusing concentration field which is secreted by the microorganism itself is\nstudied by computer simulations in spatial dimensions $d=1,2,3$. Both cases of\na chemoattractant and a chemorepellent are discussed. For a chemoattractant, we\nfind a transient dynamical arrest until the microorganism diffuses for long\ntimes. For a chemorepellent, there is a transient ballistic motion in all\ndimensions and a long-time diffusion. These results are interpreted with the\nhelp of a theoretical analysis.",
        "positive": "Diffusion on Ruffled Membrane Surfaces: We present a position Langevin equation for overdamped particle motion on\nrough two-dimensional surfaces. A Brownian Dynamics algorithm is suggested to\nevolve this equation numerically, allowing for the prediction of effective\n(projected) diffusion coefficients over corrugated surfaces. In the case of\nstatic surface roughness, we find that a simple area-scaling prediction for the\nprojected diffusion coefficient leads to seemingly quantitative agreement with\nnumerical results. To study the effect of dynamic surface evolution on the\ndiffusive process, we consider particle diffusion over a thermally fluctuating\nelastic membrane. Surface fluctuation has the effect of increasing the\neffective diffusivity toward a limiting annealed-surface value discussed\npreviously. We argue that protein motion over cell surfaces spans a variety of\nphysical regimes, making it impossible to identify a single approximation\nscheme appropriate to all measurements of interest."
    },
    {
        "anchor": "Orientationally Glassy Crystals of Janus Spheres: Colloidal Janus spheres in water (one hemisphere attractive and the other\nrepulsive) assemble into two-dimensional hexagonal crystals with orientational\norder controlled by anisotropic interactions. We exploit the decoupled\ntranslational and rotational order to quantify the orientational dynamics. Via\nimaging experiments and Monte Carlo simulations we demonstrate that the\ncorrelations in the orientation of individual Janus spheres exhibit glasslike\ndynamics that can be controlled via the ionic strength. Thus, these colloidal\nbuilding blocks provide a particularly suitable model glass system for\nelucidating nontrivial dynamics arising from directional interactions, not\ncaptured by the consideration of just translational order.",
        "positive": "Gradient Induced Droplet Motion Over Soft Solids: Fluid droplets can be induced to move over rigid or flexible surfaces under\nexternal or body forces. We describe the effect of variations in material\nproperties of a flexible substrate as a mechanism for motion. In this paper, we\nconsider a droplet placed on a substrate with either a stiffness or surface\nenergy gradient, and consider its potential for motion via coupling to elastic\ndeformations of the substrate. In order to clarify the role of contact angles\nand to obtain a tractable model, we consider a two-dimensional droplet. The\ngradients in substrate material properties give rise to asymmetric solid\ndeformation and to unequal contact angles, thereby producing a force on the\ndroplet. We then use a dynamic viscoelastic model to predict the resulting\ndynamics of droplets. Numerical results quantifying the effect of the gradients\nestablish that it is more feasible to induce droplet motion with a gradient in\nsurface energy. The results show that the magnitude of elastic modulus gradient\nneeded to induce droplet motion exceeds experimentally feasible limits in the\nproduction of soft solids and is therefore unlikely as a passive mechanism for\ncell motion. In both cases, of surface energy or elastic modulus, the threshold\nto initiate motion is achieved at lower mean values of the material properties."
    },
    {
        "anchor": "Phase separation dependent active motion of Janus lipid vesicles: Active colloidal systems have emerged as promising contenders for the future\nof microdevices. While conventional designs have extensively exploited the use\nof hard colloids, the advancement of cell-inspired architectures represents a\npivotal path towards realizing self-regulating and highly functional artificial\nmicroswimmers. In this work, we fabricate and actuate Janus lipid vesicles\ndemonstrating reconfigurable motion under an AC electric field. The giant\nunilamellar vesicles (GUVs) undergo spontaneous phase separation at room\ntemperature leading to Janus-like GUVs with two distinct lipid phases. We\nreport self-propulsion of the Janus GUVs via induced charge electroosmosis, in\nbetween parallel electrodes. Remarkably, the fluid nature of the lipid membrane\naffected by the electric field leads to asymmetry-symmetry transient states\nresulting in run-and-tumble events supported by structure domain analysis. We\ncharacterise an enhanced rotational diffusivity associated with tumble events,\ndecoupled from thermal reorientation. Lastly, we identify cargo-release\ncapabilities and a variety of shape-encoded dynamic modes in these vesicles.\nThis cell-inspired architecture provides an alternative route for creating\nmotile artificial cells and programmable microswimmers.",
        "positive": "Cracking Ion Pairs in the Electrical Double Layer of Ionic Liquids: Here we investigate a limiting case of the theory for aggregation and\ngelation in the electrical double layer (EDL) of ionic liquids (ILs). The\nlimiting case investigated only accounts for ion pairs, ignoring the\npossibility of larger clusters and a percolating ionic network. This\nsimplification, however, permits analytical solutions for the properties of the\nEDL. The resulting equations demonstrate the competition between the free\nenergy of an association and the electrostatic potential in the EDL. For small\nelectrostatic potentials and large negative free energies of associations, the\nion pairs dominate in the EDL. Whereas, for electrostatic potential energies\nlarger than the free energy of an association, electric-field-induced cracking\nof ion pairs occurs. The differential capacitance for this consistent ion\npairing theory has a propensity to have a ``double hump camel'' shape. We\ncompare this theory against previous free ion approaches, which do not\nconsistently treat the reversible associations in the EDL."
    },
    {
        "anchor": "Scaling Theory of Giant Frictional Slips in Decompressed Granular Media: When compressed frictional granular media are decompressed, generically a\nfragile configuration is created at low pressures. Typically this is\naccompanied by a giant frictional slippage as the fragile state collapses. We\nshow that this instability is understood in terms of a scaling theory with\ntheoretically computable amplitudes and exponents. The amplitude diverges in\nthe thermodynamic limit hinting to the possibility of huge frictional slip\nevents in decompressed granular media. The physics of this slippage is\ndiscussed in terms of the probability distribution functions of the tangential\nand normal forces on the grains which are highly correlated due to the Coulomb\ncondition.",
        "positive": "Effect of Elasticity on Phase Separation in Heterogeneous Systems: A recent study has demonstrated that phase separation in binary liquid\nmixtures is arrested in the presence of elastic networks and can lead to a\nnearly uniformly-sized distribution of the dilute-phase droplets. At longer\ntimescales, these droplets exhibit a directional preference to migrate along\nelastic property gradients to form a front of dissolving droplets [K. A.\nRosowski, T. Sai, E. Vidal-Henriquez, D. Zwicker, R. W. Style, E. R. Dufresne,\nElastic ripening and inhibition of liquid-liquid phase separation, Nature\nPhysics (2020) 1-4]. In this work, we develop a complete theoretical\nunderstanding of this phenomenon in nonlinear elastic solids by employing an\nenergy-based approach that captures the process at both short and long\ntimescales to determine the constitutive sensitivities and the dynamics of the\nresulting front propagation. We quantify the thermodynamic driving forces to\nidentify diffusion-limited and dissolution-limited regimes in front\npropagation. We show that changes in elastic properties have a nonlinear effect\non the process. This strong influence can have implications in a variety of\nmaterial systems including food, metals, and aquatic sediments, and further\nsubstantiates the hypothesis that biological systems exploit such mechanisms to\nregulate important function."
    },
    {
        "anchor": "Fermi level quantum numbers and secondary gap of conducting carbon\n  nanotubes: For the single-wall carbon nanotubes conducting in the simplest tight binding\nmodel, the complete set of line group symmetry based quantum numbers for the\nbands crossing at Fermi level are given. Besides linear (k), helical (k'} and\nangular momenta, emerging from roto-translational symmetries, the parities of U\naxis and (in the zig-zag and armchair cases only) mirror planes appear in the\nassignation. The helical and angular momentum quantum numbers of the crossing\nbands never vanishes, what supports proposed chirality of currents. Except for\nthe armchair tubes, the crossing bands have the same quantum numbers and,\naccording to the non-crossing rule, a secondary gap arises, as it is shown by\nthe accurate tight-binding calculation. In the armchair case the different\nvertical mirror parity of the crossing bands provides substantial conductivity,\nthough kF is slightly decreased.",
        "positive": "Poisson's ratio and angle bending in spring networks: The Poisson's ratio of a spring network system has been shown to depend not\nonly on the geometry but also on the relative strength of angle-bending forces\nin comparison to the bond-compression forces in the system. Here we derive the\nvery simple analytic result that in systems where the spring interaction\nstrength is equal to the bond-reorientation interaction, the Poisson's ratio\nidentically goes to zero and is independent of the network geometry."
    },
    {
        "anchor": "The conformation of thermoresponsive polymer brushes probed by optical\n  reflectivity: We describe a microscope-based optical setup that allows us to perform\nspace-and time-resolved measurements of the spectral reflectance of transparent\nsubstrates coated with ultrathin films. This technique is applied to\ninvestigate the behavior in water of thermosensitive polymer brushes made of\npoly(N-isopropylacrylamide) grafted on glass. We show that spectral reflectance\nmeasurements yield quantitative information about the conformation and axial\nstructure of the brushes as a function of temperature. We study how molecular\nparameters (grafting density, chain length) affect the hydra-tion state of a\nbrush, and provide one of the few experimental evidence for the occurrence of\nvertical phase separation in the vicinity of the lower critical solution\ntemperature of the polymer. The origin of the hysteretic behavior of\npoly(N-isopropylacrylamide) brushes upon cycling the temperature is also\nclarified. We thus demonstrate that our optical technique allows for in-depth\ncharacterization of stimuli-responsive polymer layers, which is crucial for the\nrational design of smart polymer coatings in actuation, gating or sensing\napplications.",
        "positive": "Evaluacion experimental del factor de estabilidad en nanoemulsiones\n  dodecano/agua: The turbidity of four different oil/water (o/w) ionic nanoemulsions is\nstudied as a function of time. The emulsions are stabilized with sodium dodecyl\nsulphate, and are composed of pure dodecane, and mixtures of dodecane, squalene\nand tetrachloroethylene. For each system plots of the stability factor as a\nfunction of the ionic strength of the solution are reported. The results allow\nestablishing the relative importance of buoyancy and Ostwald ripening on the\naggregation rates."
    },
    {
        "anchor": "Solvation and Dissociation in Weakly Ionized Polyelectrolytes: We present a Ginzburg-Landau theory of inhomogeneous polyelectrolytes with a\npolar solvent. First, we take into account the molecular (solvation)\ninteraction among the ions, the charged monomers, the uncharged monomers, and\nthe solvent molecules, together with the electrostatic interaction with a\ncomposition-dependent dielectric constant. Second, we treat the degree of\nionization as a fluctuating variable dependent on the local electric potential.\nWith these two ingredients included, our results are as follows. (i) We derive\na mass reaction law and a general expression for the surface tension. (ii) We\ncalculate the structure factor of the composition fluctuations as a function of\nvarious parameters of the molecular interactions, which provides a general\ncriterion of the formation of mesophases. (iii) We numerically examine some\ntypical examples of interfaces and mesophase structures, which strongly depend\non the molecular interaction parameters.",
        "positive": "Elasticity and Viscosity of a Lyotropic Chromonic Nematic Studied with\n  Dynamic Light Scattering: Using dynamic light scattering, we measure for the first time the\ntemperature-dependent elastic moduli and associated orientational viscosity\ncoefficients of the nematic phase in a self-assembled lyotropic chromonic\nliquid crystal. The bend K3 and splay K1 moduli are an order of magnitude\nhigher than the twist K2 constant. The ratio K3/K1 shows an anomalous increase\nwith temperature; we attribute this to the shortening of the aggregates as\ntemperature increases. The viscosity coefficients also show a significant\nanisotropy, as well as a strong temperature dependence; in particular, the bend\nviscosity is three orders of magnitude smaller than the splay and twist\nviscosities."
    },
    {
        "anchor": "Self-sustained lift and low friction via soft lubrication: Relative motion between soft wet solids arises in a number of applications in\nnatural and artificial settings, and invariably couples elastic deformation and\nfluid flow. We explore this in a minimal setting by considering a\nfluid-immersed negatively-buoyant cylinder moving along a soft inclined wall.\nOur experiments show that there is an emergent robust steady-state sliding\nregime of the cylinder with an effective friction that is significantly reduced\nrelative to that of rigid fluid-lubricated contacts. A simple scaling approach\nthat couples the cylinder-induced flow to substrate deformation allows us to\nexplain the emergence of an elastohydrodynamic lift that underlies the\nself-sustained lubricated motion of the cylinder, consistent with recent\ntheoretical predictions. Our results suggest an explanation for a range of\neffects such as reduced wear in animal joints and long-runout landslides, and\ncan be couched as a design principle for low-friction interfaces.",
        "positive": "Universality of Ionic Criticality: Size- and Charge-Asymmetric\n  Electrolytes: Grand canonical simulations designed to resolve critical universality classes\nare reported for $z$:1 hard-core electrolyte models with diameter ratios\n$\\lambda {=} a_+/a_- {\\lesssim} 6$. For $z {=} 1$ Ising-type behavior prevails.\nUnbiased estimates of $T_c(\\lambda)$ are within 1% of previous (biased)\nestimates but the critical densities are $\\sim $5 % lower. Ising character is\nalso established for the 2:1 and 3:1 equisized models, along with critical\namplitudes and improved $T_c$ estimates. For $z {=} 3$, however, strong\nfinite-size effects reduce the confidence level although classical and O$(n\n{\\geq} 3)$ criticality are excluded."
    },
    {
        "anchor": "Self-diffusion in inhomogeneous granular shearing flows: In this letter, we discuss how flow inhomogeneity affects the self-diffusion\nbehavior in granular flows. Whereas self-diffusion scalings have been well\ncharacterized in the past for homogeneous shearing, the effect of shear\nlocalization and nonlocality of the flow has not been studied. We therefore\npresent measurements of self-diffusion coefficients in discrete numerical\nsimulations of steady, inhomogeneous, and collisional shearing flows of nearly\nidentical, frictional, and inelastic spheres. We focus on a wide range of dense\nsolid volume fractions, that correspond to geophysical and industrial shearing\nflows that are dominated by collisional interactions. We compare the measured\nvalues first, with a scaling based on shear rate and, then, on a scaling based\non the granular temperature. We find that the latter does much better than the\nformer in collapsing the data. The results lay the foundations of diffusion\nmodels for inhomogeneous shearing flows, which should be useful in treating\nproblems of mixing and segregation.",
        "positive": "On Kinetic Equations for Collisional Dynamics of Active Soft Condensed\n  Matter: We consider a new approach to the description of the collective behavior of\ncomplex systems of mathematical biology based on the evolution equations for\nobservables of such systems. This representation of the kinetic evolution\nseems, in fact, the direct mathematically fully consistent formulation modeling\nthe collective behavior of biological systems since the traditional notion of\nthe state in kinetic theory is more subtle and it is an implicit characteristic\nof the populations of living creatures."
    },
    {
        "anchor": "On the statistical mechanics of shape fluctuations of nearly spherical\n  lipid vesicle: The mechanical properties of biological membranes play an important role in\nthe structure and the functioning of living organisms. One of the most widely\nused methods for determination of the bending elasticity modulus of the model\nlipid membranes (simplified models of the biomembranes with similar mechanical\nproperties) is analysis of the shape fluctuations of the nearly spherical lipid\nvesicles. A theoretical basis of such an analysis is developed by Milner and\nSafran. In the present studies we analyze their results using an approach based\non the Bogoljubov inequalities and the approximating Hamiltonian method. This\napproach is in accordance with the principles of statistical mechanics and is\nfree of contradictions. Our considerations validate the results of Milner and\nSafran if the stretching elasticity K_s of the membrane tends to zero.",
        "positive": "Particle sizing by dynamic light scattering: non-linear cumulant\n  analysis: We revisit the method of cumulants for analysing dynamic light scattering\ndata in particle sizing applications. Here the data, in the form of the time\ncorrelation function of scattered light, is written as a series involving the\nfirst few cumulants (or moments) of the distribution of particle diffusion\nconstants. Frisken (2001 Applied Optics 40, 4087) has pointed out that, despite\ngreater computational complexity, a non-linear, iterative, analysis of the data\nhas advantages over the linear least-squares analysis used originally. In order\nto explore further the potential and limitations of cumulant methods we\nanalyse, by both linear and non-linear methods, computer-generated data with\nrealistic `noise', where the parameters of the distribution can be set\nexplicitly. We find that, with modern computers, non-linear analysis is\nstraightforward and robust. The mean and variance of the distribution of\ndiffusion constants can be obtained quite accurately for distributions of width\n(standard deviation/mean) up to about 0.6, but there appears to be little\nprospect of obtaining meaningful higher moments."
    },
    {
        "anchor": "MMM2D: A fast and accurate summation method for electrostatic\n  interactions in 2D slab geometries: We present a new method, in the following called MMM2D, to accurately\ncalculate the electrostatic energy and forces on charges being distributed in a\ntwo dimensional periodic array of finite thickness. It is not based on an Ewald\nsummation method and as such does not require any fine-tuning of an Ewald\nparameter for convergence. We transform the Coulomb sum via a convergence\nfactor into a series of fast decaying functions which can be easily evaluated.\nRigorous error bounds for the energies and the forces are derived and\nnumerically verified. Already for small systems our method is much faster than\nthe traditional 2D-Ewald methods, but for large systems it is clearly superior\nbecause its time demand scales like O(N^{5/3}) with the number N of charges\nconsidered. Moreover it shows a rapid convergence, is very precise and easy to\nhandle.",
        "positive": "Dynamics of cluster formation in driven dipolar colloids dispersed on a\n  monolayer: We report computer simulation results on the cluster formation of dipolar\ncolloidal particles driven by a rotating external field in a\nquasi-two-dimensional setup. We focus on the interplay between permanent\ndipolar and hydrodynamic interactions and its influence on the dynamic behavior\nof the particles. This includes their individual as well as their collective\nmotion. To investigate these characteristics, we employ Brownian dynamics\nsimulations of a finite system with and without hydrodynamic interactions. Our\nresults indicate that particularly the translation-rotation coupling from the\nhydrodynamic interactions has a profound impact on the clustering behavior."
    },
    {
        "anchor": "Consolidation of freshly deposited cohesive and non-cohesive sediment:\n  particle-resolved simulations: We analyze the consolidation of freshly deposited cohesive and non-cohesive\nsediment by means of particle-resolved direct Navier-Stokes simulations based\non the Immersed Boundary Method. The computational model is parameterized by\nmaterial properties and does not involve any arbitrary calibrations. We obtain\nthe stress balance of the fluid-particle mixture from first principles and link\nit to the classical effective stress concept. The detailed datasets obtained\nfrom our simulations allow us to evaluate all terms of the derived stress\nbalance. We compare the settling of cohesive sediment to its non-cohesive\ncounterpart, which corresponds to the settling of the individual primary\nparticles. The simulation results yield a complete parameterization of the\nGibson equation, which has been the method of choice to analyze self-weight\nconsolidation.",
        "positive": "Maxwell field $ \\mathbf{E}$ in a two-dimensional polar fluid in the\n  presence of an external field $\\boldsymbol{\\mathcal{E}} $ : a Monte-Carlo\n  study: We study a two-dimensional system of dipolar hard disks in the presence of a\nuniform external electric field $\\boldsymbol{\\mathcal{E}} $ by Monte Carlo\nsimulations in a square with periodic boundary conditions. The study is\nperformed in both the fluid at high temperature and the phase of living\npolymers at low temperature. In the considered geometry the macroscopic Maxwell\nfield $ \\mathbf{E}$ is computed and found to be equal to the external field\n$\\boldsymbol{\\mathcal{E}} $ in both phases. The dielectric properties of the\nsystem in the liquid phase as well as in the polymeric phase are investigated."
    },
    {
        "anchor": "Examination of saturation coverage of polygons using random sequential\n  adsorption algorithm: The goal of random sequential adsorption (RSA), a time-dependent packing\nmethod, is to create a regular or asymmetric covering of an empty space that\ncan fit in the allocated space without overlapping. The density of coverage\ntends to reach a limit in the infinite-time limit. We attempt to estimate\nsaturated packing of oriented 2-D polygons, including squares(4-sides), regular\npentagons (5-sides), regular hexagons (6-sides), regular heptagons (7-sides),\nregular octagons (8-sides), regular nonagons (9-sides), regular decagons\n(10-sides), and regular dodecagons (12-sides), in this study. We obtained\nresults that are consistent with previous, extrapolation-based studies1. We\nutilised the \"separating axis theorem\" to determine if there is overlap between\narriving polygons and those that have previously been placed. Saturation as a\nlower limit is considered to have been reached when RSA addition becomes\nexcessively slow, according to us.",
        "positive": "Triple junction at the triple point resolved on the individual particle\n  level: At the triple point of a repulsive screened Coulomb system, a\nface-centered-cubic (fcc) crystal, a body-centered-cubic (bcc) crystal and a\nfluid phase coexist. At their intersection, these three phases form a liquid\ngroove, the triple junction. Using confocal microscopy, we resolve the triple\njunction on a single particle level in a model system of charged PMMA colloids\nin a nonpolar solvent. The groove is found to be extremely deep and the\nincommensurate solid-solid interface to be very broad. Thermal fluctuations\nhence appear to dominate the solid-solid interface. This indicates a very low\ninterfacial energy. The fcc-bcc interfacial energy is quantitatively determined\nbased on Young's equation and, indeed, it is only about 1.3 times higher than\nthe fcc-fluid interfacial energy close to the triple point."
    },
    {
        "anchor": "Three-body Interactions Drive the Transition to Polar Order in a Simple\n  Flocking Model: A large class of mesoscopic or macroscopic flocking theories are\ncoarse-grained from microscopic models that feature binary interactions as the\nchief aligning mechanism. However while such theories seemingly predict the\nexistence of polar order with just binary interactions, actomyosin motility\nassay experiments show that binary interactions are insufficient to obtain\npolar order, especially at high densities. To resolve this paradox, here we\nintroduce a solvable one-dimensional flocking model and derive its stochastic\nhydrodynamics. We show that two-body interactions are insufficient to generate\npolar order unless the noise is non-Gaussian. We show that noisy three-body\ninteractions in the microscopic theory allow us to capture all essential\ndynamical features of the flocking transition, in systems that achieve\norientational order above a critical density.",
        "positive": "Learning to Control Active Matter: The study of active matter has revealed novel non-equilibrium collective\nbehaviors, illustrating their potential as a new materials platform. However,\nmost works treat active matter as unregulated systems with uniform microscopic\nenergy input, which we refer to as activity. In contrast, functionality in\nbiological materials results from regulating and controlling activity locally\nover space and time, as has only recently become experimentally possible for\nengineered active matter. Designing functionality requires navigation of the\nhigh dimensional space of spatio-temporal activity patterns, but brute force\napproaches are unlikely to be successful without system-specific intuition.\nHere, we apply reinforcement learning to the task of inducing net transport in\na specific direction for a simulated system of Vicsek-like self-propelled disks\nusing a spotlight that increases activity locally. The resulting time-varying\npatterns of activity learned exploit the distinct physics of the strong and\nweak coupling regimes. Our work shows how reinforcement learning can reveal\nphysically interpretable protocols for controlling collective behavior in\nnon-equilibrium systems."
    },
    {
        "anchor": "Efficient Navigation of Colloidal Robots in an Unknown Environment via\n  Deep Reinforcement Learning: Equipping active colloidal robots with intelligence such that they can\nefficiently navigate in unknown complex environments could dramatically impact\ntheir use in emerging applications like precision surgery and targeted drug\ndelivery. Here we develop a model-free deep reinforcement learning that can\ntrain colloidal robots to learn effective navigation strategies in unknown\nenvironments with random obstacles. We show that trained robot agents learn to\nmake navigation decisions regarding both obstacle avoidance and travel time\nminimization, based solely on local sensory inputs without prior knowledge of\nthe global environment. Such agents with biologically inspired mechanisms can\nacquire competitive navigation capabilities in large-scale, complex\nenvironments containing obstacles of diverse shapes, sizes, and configurations.\nThis study illustrates the potential of artificial intelligence in engineering\nactive colloidal systems for future applications and constructing complex\nactive systems with visual and learning capability.",
        "positive": "Build up of yield stress fluids via chaotic emulsification: Stabilized dense emulsions display a rich phenomenology connecting\nmicrostructure and rheology. In this work we study how an emulsion with a\nfinite yield stress can be built via large-scale stirring. By gradually\nincreasing the volume fraction of the dispersed minority phase, under the\nconstant action of a stirring force, we are able to achieve volume fractions\nclose to $80\\%$. Despite the fact that our system is highly concentrated and\nnot yet turbulent we observe a droplet size distribution consistent with the\n$-10/3$ scaling, often associated to inertial range droplets breakup. We report\nthat the polydispersity of droplet sizes correlates with the dynamics of the\nemulsion formation process. Additionally we quantify the visco-elastic\nproperties of the dense emulsion finally obtained and we demonstrate the\npresence of a finite yield stress. The approach reported can pave the way to a\nquantitative understanding of the complex interplay between the dynamics of\nmesoscale constituents and the large scale flow properties yield-stress fluids."
    },
    {
        "anchor": "Phase Transition and Separation for Mixture of Liquid He-3 and He-4: This article introduces a dynamical Ginzburg-Landau phase\ntransition/separation model for the mixture of liquid helium-3 and helium-4,\nusing a unified dynamical Ginzburg-Landau model for equilibrium phase\ntransitions. The analysis of this model leads to three critical length scales\nL1 < L2 < L3, detailed theoretical phase diagrams and transition properties\nwith different length scales of the container.",
        "positive": "Nanosecond electro-optics of nematic liquid crystal with negative\n  dielectric anisotropy: We study a nanosecond electro-optic response of a nematic liquid crystal in a\ngeometry where an applied electric field $\\textbf{E}$ modifies the tensor order\nparameter but does not change the orientation of the optic axis (director\n$\\hat{\\textbf{N}}$). We use a nematic with negative dielectric anisotropy with\nthe electric field applied perpendicularly to $\\hat{\\textbf{N}}$. The field\nchanges the dielectric tensor at optical frequencies (optic tensor) due to the\nfollowing mechanisms: (a) nanosecond creation of the biaxial orientational\norder; (b) uniaxial modification of the orientational order that occurs over\ntimescales of tens of nanoseconds, and (c) the quenching of director\nfluctuations with a wide range of characteristic times up to milliseconds. We\ndevelop a model to describe the dynamics of all three mechanisms. We design the\nexperimental conditions to selectively suppress the contributions from\nfluctuations quenching (c) and from the biaxial order effect (a) and thus,\nseparate the contributions of the three mechanisms in the electro-optic\nresponse. As a result, the experimental data can be well fitted with the model.\nThe analysis provides a detailed physical picture of how the liquid crystal\nresponds to a strong electric field on a timescale of nanoseconds. This work\nprovides a useful guide in the current search of the biaxial nematic phase.\nNamely, the temperature dependence of the biaxial susceptibility allows one to\nestimate the temperature of the potential uniaxial-to-biaxial phase transition.\nAn analysis of the fluctuations quenching indicates that on a timescale of\nnanoseconds, the classic model with constant viscoelastic material parameters\nmight reach its limit of validity. The effect of nanosecond electric\nmodification of the order parameter (NEMOP) can be used in applications in\nwhich one needs to achieve ultrafast (nanosecond) changes of optical\ncharacteristics."
    },
    {
        "anchor": "Effects of Monovalent and Divalent Cations on the Rheology of Entangled\n  DNA: In this paper we investigate the effects of varying cation valency and\nconcentration on the rheology of entangled lambda DNA solutions. We show that\nmonovalent cations moderately increase the viscoelasticty of the solutions\nmainly by stabilising linear condensation of lambda DNA ``monomers'' via\nhybridisation of their sticky ends. On the contrary, divalent cations have a\nfar more complex and dramatic effect on the rheology of the solution and we\nobserve evidence of inter-molecular DNA-DNA bridging by Mg2+. We argue that\nthese results may be interesting in the context of dense solutions of single\nand double stranded DNA, e.g. in vivo or in biotechnology applications such as\nDNA origami and DNA hydrogels.",
        "positive": "Acoustically mediated long-range interaction among multiple spherical\n  particles exposed to a plane standing wave: In this work, we study the acoustically mediated interaction forces among\nmultiple well-separated spherical particles trapped in the same node or\nantinode plane of a standing wave. An analytical expression of the acoustic\ninteraction force is derived, which is accurate even for the particles beyond\nthe Rayleigh limit. Interestingly, the multi-particle system can be decomposed\ninto a series of independent two-particle systems described by pairwise\ninteractions. Each pairwise interaction is a long-range interaction, as\ncharacterized by a soft oscillatory attenuation (at the power exponent of n=-1\nor -2). The vector additivity of the acoustic interaction force, which is not\nwell expected considering the nonlinear nature of the acoustic radiation force,\nis greatly useful for exploring a system consisting of a large number of\nparticles. The capability of self-organizing a big particle cluster can be\nanticipated through such acoustically controllable long-range interaction."
    },
    {
        "anchor": "Atomic layering at the liquid silicon surface: a first- principles\n  simulation: We simulate the liquid silicon surface with first-principles molecular\ndynamics in a slab geometry. We find that the atom-density profile presents a\npronounced layering, similar to those observed in low-temperature liquid metals\nlike Ga and Hg. The depth-dependent pair correlation function shows that the\neffect originates from directional bonding of Si atoms at the surface, and\npropagates into the bulk. The layering has no major effects in the electronic\nand dynamical properties of the system, that are very similar to those of bulk\nliquid Si. To our knowledge, this is the first study of a liquid surface by\nfirst-principles molecular dynamics.",
        "positive": "Efficiency of initiating cell adhesion in hydrodynamic flow: We theoretically investigate the efficiency of initial binding between a\nreceptor-coated sphere and a ligand-coated wall in linear shear flow. The mean\nfirst passage time for binding decreases monotonically with increasing shear\nrate. Above a saturation threshold of the order of a few 100 receptor patches,\nthe binding efficiency is enhanced only weakly by increasing their number and\nsize, but strongly by increasing their height. This explains why white blood\ncells in the blood flow adhere through receptor patches localized to the tips\nof microvilli, and why malaria-infected red blood cells form elevated receptor\npatches (knobs)."
    },
    {
        "anchor": "Anisotropy of the monomer random walk in a polymer melt: local-order and\n  connectivity effects: The random walk of a bonded monomer in a polymer melt is anisotropic due to\nlocal order and bond connectivity. We investigate both effects by\nmolecular-dynamics simulations on melts of fully-flexible linear chains ranging\nfrom dimers ($M=2$) up to entangled polymers ($M=200$). The corresponding\natomic liquid is also considered as reference system. To disentangle the\ninfluence of the local geometry and the bond arrangements, and reveal their\ninterplay, we define suitable measures of the anisotropy emphasising either the\nformer or the latter aspect. Connectivity anisotropy, as measured by the\ncorrelation between the initial bond orientation and the direction of the\nsubsequent monomer displacement, shows a slight enhancement due to the local\norder at times shorter than the structural relaxation time. At intermediate\ntimes - when the monomer displacement is comparable to the bond length - a\npronounced peak and then decays slowly as $t^{-1/2}$, becoming negligible when\nthe displacements is as large as about five bond lengths, i.e. about four\nmonomer diameters or three Kuhn lengths. Local-geometry anisotropy, as measured\nby the correlation between the initial orientation of a characteristic axis of\nthe Voronoi cell and the subsequent monomer dynamics, is affected at shorter\ntimes than the structural relaxation time by the cage shape with antagonistic\ndisturbance by the connectivity. Differently, at longer times, the connectivity\nfavours the persistence of the local-geometry anisotropy which vanishes when\nthe monomer displacement exceeds the bond length. Our results strongly suggest\nthat the sole consideration of the local order is not enough to understand the\nmicroscopic origin of the rattling amplitude of the trapped monomer in the cage\nof the neighbours.",
        "positive": "Traces of surfactants can severely limit the drag reduction of\n  superhydrophobic surfaces: Superhydrophobic surfaces (SHSs) have the potential to achieve large drag\nreduction for internal and external flow applications. However, experiments\nhave shown inconsistent results, with many studies reporting significantly\nreduced performance. Recently, it has been proposed that surfactants,\nubiquitous in flow applications, could be responsible, by creating adverse\nMarangoni stresses. Yet, testing this hypothesis is challenging. Careful\nexperiments with purified water show large interfacial stresses and,\nparadoxically, adding surfactants yields barely measurable drag increases. This\nsuggests that other physical processes, such as thermal Marangoni stresses or\ninterface deflection, could explain the lower performance. To test the\nsurfactant hypothesis, we perform the first numerical simulations of flows over\na SHS inclusive of surfactant kinetics. These simulations reveal that\nsurfactant-induced stresses are significant at extremely low concentrations,\npotentially yielding a no-slip boundary condition on the air--water interface\n(the \"plastron\") for surfactant amounts below typical environmental values.\nThese stresses decrease as the streamwise distance between plastron stagnation\npoints increases. We perform microchannel experiments with thermally-controlled\nSHSs consisting of streamwise parallel gratings, which confirm this numerical\nprediction. We introduce a new, unsteady test of surfactant effects. When we\nrapidly remove the driving pressure following a loading phase, a backflow\ndevelops at the plastron, which can only be explained by surfactant gradients\nformed in the loading phase. This demonstrates the significance of surfactants\nin deteriorating drag reduction, and thus the importance of including\nsurfactant stresses in SHS models. Our time-dependent protocol can assess the\nimpact of surfactants in SHS testing and guide future mitigating designs."
    },
    {
        "anchor": "Liquid crystal self-assembly of upconversion nanorods enriched by\n  depletion forces for mesostructured material preparation: Monodisperse rod-like colloidal particles are known for spontaneously forming\nboth nematic and smectic liquid crystal phases, but their self-assembly was\ntypically exploited from the fundamental soft condensed matter physics\nperspective. Here we demonstrate that depletion interactions, driven by\nnon-adsorbing polymers like dextran and surfactants, can be used to enrich\nself-organization of photon-upconversion nanorods into orientationally ordered\nnematic and smectic-like membrane colloidal superstructures. We study\nthermodynamic phase diagrams and demonstrate polarization-dependent photon\nupconversion exhibited by the ensuing composites, which arises from the\nsuperposition of unique properties of the solid nanostructures and the\nlong-range ordering enabled by liquid crystalline self-organization. Finally,\nwe discuss how our method of utilizing self-assembly due to the steric and\nelectrostatic interactions, along with attractive depletion forces, can enable\ntechnological uses of lyotropic colloidal liquid crystals and mesostructured\ncomposite materials enabled by them, even when they are formed by anisotropic\nnanoparticles with relatively small aspect ratios.",
        "positive": "Evaluating the Applicability of the Fokker-Planck Equation in Polymer\n  Translocation: A Brownian Dynamics Study: Brownian dynamics (BD) simulations are used to study the translocation\ndynamics of a coarse-grained polymer through a cylindrical nanopore. We\nconsider the case of short polymers, with a polymer length, N, in the range\nN=21-61. The rate of translocation is controlled by a tunable friction\ncoefficient, gamma_{0p}, for monomers inside the nanopore. In the case of\nunforced translocation, the mean translocation time scales with polymer length\nN as <tau_1>~ (N-N_p)^alpha, where N_p is the average number of monomers in the\nnanopore. The exponent approaches the value alpha=2 when the pore friction is\nsufficiently high, in accord with the prediction for the case of the\nquasi-static regime where pore friction dominates. In the case of forced\ntranslocation, the polymer chain is stretched and compressed on the cis and\ntrans sides, respectively, for low gamma_{0p}. However, the chain approaches\nconformational quasi-equilibrium for sufficiently large gamma_{0p}. In this\nlimit the observed scaling of <tau_1> with driving force and chain length\nsupports the FP prediction that <tau> is proportional to N/f_d for sufficiently\nstrong driving force. Monte Carlo simulations are used to calculate\ntranslocation free energy functions for the system. The free energies are used\nwith the Fokker-Planck equation to calculate translocation time distributions.\nAt sufficiently high gamma_{0p}, the predicted distributions are in excellent\nagreement with those calculated from the BD simulations. Thus, the FP equation\nprovides a valid description of translocation dynamics for sufficiently high\npore friction for the range of polymer lengths considered here. Increasing N\nwill require a corresponding increase in pore friction to maintain the validity\nof the FP approach. Outside the regime of low N and high pore friction, the\npolymer is out of equilibrium, and the FP approach is not valid."
    },
    {
        "anchor": "Fan-shaped and toric textures of mesomorphic oxadiazoles: When a family of non symmetrical heterocycled compounds is investigated, a\nvariety of mesophases can be observed with rather different features. Here we\nreport the behaviour of seven different members among a family of such\nmaterials, that consists of mesomorphic oxadiazole compounds. In two of these\ncompounds, the optical microscope investigation shows very interesting\nbehaviours. In their smectic phases, fan-shaped and toric textures, sometimes\nwith periodic instability, are observed. Moreover, the nematic phase displays a\ntexture transition. Texture transitions have been previously observed only\ninside the nematic phase of some compounds belonging to the families of the\noxybenzoic and cyclohexane acids. In these two oxadiazole compounds we can\nobserve what we define as a \"toric nematic phase\", heating the samples from the\nsmectic phase. The toric nematic texture disappears as the sample is further\nheated, changing into a smooth texture.",
        "positive": "Pattern engineering of living bacterial colonies using meniscus-driven\n  fluidic channels: Engineering spatially organized biofilms for creating adaptive and\nsustainable biomaterials is a forthcoming mission of synthetic biology.\nExisting technologies of patterning biofilm materials suffer limitations\nassociated with the high technical barrier and the requirements of special\nequipment. Here we present controlled meniscus-driven fluidics, MeniFluidics;\nan easily implementable technique for patterning living bacterial populations.\nWe demonstrate multiscale patterning of living-colony and biofilm formation\nwith submillimetre resolution. Relying on fast bacterial spreading in liquid\nchannels, MeniFluidics allows controlled anisotropic bacterial colonies\nexpansion both in space and time. The technique has also been applied for\nstudying collective phenomena in confined bacterial swarming and organizing\ndifferent fluorescently labelled Bacillus subtilis strains into a converged\npattern. We believe that the robustness and low technical barrier of\nMeniFluidics offer a tool for developing living functional materials,\nbioengineering and bio-art, and adding to fundamental research of microbial\ninteractions."
    },
    {
        "anchor": "On a \"Robust\" A-like State of $^3He$ in Aerogel: The orbitally isotropic Equal Spin Pairing (ESP) state has been proposed in\nRef. [1] as a candidate of an A-like phase of superfluid $^3He$ in aerogel\nenvironment. In order to preserve an exact isotropy of the state in the\npresence of the magnetic field the condensate with equal values of the\namplitudes $\\Delta_{\\uparrow\\uparrow}$ and $\\Delta_{\\downarrow\\downarrow}$ was\nadopted. Experimentally it is established that this version does not reproduce\nobserved splitting asymmetry of ESP phase in aerogel under the action of an\nexternal magnetic field. Here we explore the behavior of the quasi-isotropic\nversion of an axiplanar ESP phase with $\\Delta_{\\uparrow\\uparrow}\\neq\n\\Delta_{\\downarrow\\downarrow}$ and show that for this state the splitting\nasymmetry ratio could be reconciled with experimental observations.",
        "positive": "Nonequilibrium Fluctuations, Travelling Waves, and Instabilities in\n  Active Membranes: The stability of a flexible fluid membrane containing a distribution of\nmobile, active proteins (e.g. proton pumps) is shown to depend on the structure\nand functional asymmetry of the proteins. A stable active membrane is in a\nnonequilibrium steady state with height fluctuations whose statistical\nproperties are governed by the protein activity. Disturbances are predicted to\ntravel as waves at sufficiently long wavelength, with speed set by the normal\nvelocity of the pumps. The unstable case involves a spontaneous, pump-driven\nundulation of the membrane, with clumping of the proteins in regions of high\nactivity."
    },
    {
        "anchor": "Correlation functions and thermophysical properties of one-dimensional\n  liquids: The properties of one-dimensional liquids are studied for several interaction\npotentials for which, under certain assumptions, the properties of the system\nadmit an analytical solution. The studied potentials are the triangle-well and\nthe ramp potential, and then we use the knowledge of these ones to study the\nhard-rod and the sticky-hard-rod potentials. For each one of these potentials,\nwe study its equation of state and other thermodynamic quantities such as the\ncompressibility factor and the internal energy. Then, we study its correlation\nfunctions, such as the radial distribution function, the structure factor and\nthe direct correlation function. For the latter one, the approximations known\nas Percus--Yevick and hypernetted-chain have been compared to the analytical\nresult. Finally, the asymptotic behaviour of the radial distribution function\nis studied and the Fisher--Widom line computed for the triangle-well potential.",
        "positive": "Transport coefficients of self-propelled particles: Reverse\n  perturbations and transverse current correlations: The reverse perturbation method [Phys. Rev. E 59, 4894 (1999)] for shearing\nsimple liquids and measuring their viscosity is extended to the Vicsek-model\n(VM) of active particles [Phys. Rev. Lett. 75, 1226 (1995)] and its metric-free\nversion. The sheared systems exhibit a phenomenon that is similar to the skin\neffect of an alternating electric current: momentum that is fed into the\nboundaries of a layer decays mostly exponentially towards the center of the\nlayer. It is shown how two transport coefficients, i.e. the shear viscosity\n$\\nu$ and the momentum amplification coefficient $\\lambda$, can be obtained by\nfitting this decay with an analytical solution of the hydrodynamic equations\nfor the VM. The viscosity of the VM consists of two parts, a kinetic and a\ncollisional contribution. While analytical predictions already exist for the\nformer, a novel expression for the collisional part is derived by an\nEnskog-like kinetic theory. To verify the predictions for the transport\ncoefficients, Green-Kubo relations were evaluated and transverse current\ncorrelations were measured in independent simulations. Not too far to the\ntransition to collective motion, we find excellent agreement between the\ndifferent measurements of the transport coefficients. However, the measured\nvalues of $\\nu$ and $1-\\lambda$ are always slightly higher than the mean-field\npredictions, even at large mean free paths and at state points quite far from\nthe threshold to collective motion, that is, far in the disordered phase. These\nfindings seem to indicate that the mean-field assumption of molecular chaos is\nmuch less reliable in systems with velocity-alignment rules such as the VM,\ncompared to models obeying detailed balance such as Multi-Particle Collision\nDynamics."
    },
    {
        "anchor": "Phase behavior of water-like models in nanoscopic pores of slit shape.\n  Predictions from a density functional theory: We have explored the phase behavior of a set of water-like models in slit\npores of nanoscopic dimensions. The interaction between water and pore walls\nmimics the graphite surface. A version of density functional method is used as\ntheoretical tools. The fluid models are adopted from the work of Clark et al.\n[Mol. Phys., 2006, 104, 3561]. They reproduce the bulk water vapor-liquid\ncoexistence envelope adequately. Our principal focus is on changes of topology\nof the phase diagram of confined water and establishing trends of behavior of\nthe crossover temperature between condensation and evaporation on the strength\nof water-graphite interaction potential. Growth of the water film on the pore\nwalls is illustrated in terms of the density profiles. Theoretical results are\ndiscussed in context of computer simulation findings for water models in pores.",
        "positive": "A unifying mechanism to explain the rate dependent rheological behavior\n  in non-Brownian suspensions: One curve to unify them all: We propose a unifying mechanism based on the Stribeck curve for the\ncoefficient of friction between the particles to capture the shear thinning -\nNewtonian plateau - shear thickening - shear thinning rheological behavior at\nlow - intermediate - beyond critical - high shear rates, respectively, for a\ntypical dense non-Brownian suspension. We establish the accuracy of the\nproposed model by comparing the numerical results with experimental data. The\npresence of non-DLVO (Derjaguin and Landau, Verwey and Overbeek) forces and a\ncoefficient of friction reducing with asperity deformation explain the\nexistence of the Newtonian plateau at the intermediate shear rates and the\nsecond shear thinning regime at high shear rates, respectively."
    },
    {
        "anchor": "Steady-state rheology and structure of soft hybrid mixtures of liquid\n  crystals and magnetic nanoparticles: Using non-equilibrium molecular dynamics simulations, we study the rheology\nof a model hybrid mixture of liquid crystals (LCs) and dipolar soft spheres\n(DSS) representing magnetic nanoparticles. The bulk isotropic LC-DSS mixture is\nsheared with different shear rates using Lees-Edwards periodic boundary\nconditions. The steady-state rheological properties and the effect of the shear\non the microstructure of the mixture are studied for different strengths of the\ndipolar coupling, $\\lambda$, among the DSS. We find that at large shear rates,\nthe mixture shows a shear-thinning behavior for all considered values of\n$\\lambda$. At low and intermediate values of $\\lambda$, a crossover from\nNewtonian to non-Newtonian behavior is observed as the rate of applied shear is\nincreased. In contrast, for large values of $\\lambda$, such a crossover is not\nobserved within the range of shear rates considered. Also, the extent of the\nnon-Newtonian regime increases as $\\lambda$ is increased. These features can be\nunderstood via the shear-induced changes of the microstructure. In particular,\nthe LCs display a shear-induced isotropic-to-nematic transition at large shear\nrates with a shear-rate dependent degree of nematic ordering. The DSS show a\nshear-induced nematic ordering only for large values of $\\lambda$, where the\nparticles self-assemble into chains. Moreover, at large $\\lambda$ and low shear\nrates, our simulations indicate that the DSS form ferromagnetic domains.",
        "positive": "Swimming suppresses correlations in dilute suspensions of pusher\n  microorganisms: Active matter exhibits various forms of non-equilibrium states in the absence\nof external forcing, including macroscopic steady-state currents. Such states\nare often too complex to be modelled from first principles and our\nunderstanding of their physics relies heavily on minimal models. These have\nmostly been studied in the case of \"dry\" active matter, where particle dynamics\nare dominated by friction with their surroundings. Significantly less is known\nabout systems with long-range hydrodynamic interactions that belong to \"wet\"\nactive matter. Dilute suspensions of motile bacteria, modelled as\nself-propelled dipolar particles interacting solely through long-ranged\nhydrodynamic fields, are arguably the most studied example from this class of\nactive systems. Their phenomenology is well-established: at sufficiently high\ndensity of bacteria, there appear large-scale vortices and jets comprising many\nindividual organisms, forming a chaotic state commonly known as bacterial\nturbulence. As revealed by computer simulations, below the onset of collective\nmotion, the suspension exhibits very strong correlations between individual\nmicroswimmers stemming from the long-ranged nature of dipolar fields. Here we\ndemonstrate that this phenomenology is captured by the minimal model of\nmicroswimmers. We develop a kinetic theory that goes beyond the commonly used\nmean-field assumption, and explicitly takes into account such correlations.\nNotably, these can be computed exactly within our theory. We calculate the\nfluid velocity variance, spatial and temporal correlation functions, the fluid\nvelocity spectrum, and the enhanced diffusivity of tracer particles. We find\nthat correlations are suppressed by particle self-propulsion, although the\nmean-field behaviour is not restored even in the limit of very fast swimming."
    },
    {
        "anchor": "Microscopic origin of tunable assembly forces in chiral active\n  environments: The fluctuations of a nonequilibrium bath enable dynamics inaccessible to any\nequilibrium system. Exploiting the driven dynamics of active matter in order to\ndo useful work has become a topic of significant experimental and theoretical\ninterest. Due to the unique modalities controlling self-assembly, the interplay\nbetween passive solutes and the particles in an active bath has been studied as\na potential driving force to guide assembly of otherwise non-interacting\nobjects. Here, we investigate and characterize the microscopic origins of the\nattractive and repulsive interactions between passive solutes in an active\nbath. We show that, while assembly does not occur dynamically for achiral\nactive baths, chiral active particles can produce stable and robust assembly\nforces. We both explain the observed oscillatory force profile for active\nBrownian particles and demonstrate that chiral active motion leads to fluxes\nconsistent with an odd diffusion tensor that, when appropriately tuned,\nproduces long-ranged assembly forces.",
        "positive": "The role of correlations in the collective behaviour of microswimmer\n  suspensions: In this Letter, we study the collective behaviour of a large number of\nself-propelled microswimmers immersed in a fluid. Using unprecedently\nlarge-scale lattice Boltzmann simulations, we reproduce the transition to\nbacterial turbulence. We show that, even well below the transition, swimmers\nmove in a correlated fashion that cannot be described by a mean-field approach.\nWe develop a novel kinetic theory that captures these correlations and is\nnon-perturbative in the swimmer density. To provide an experimentally\naccessible measure of correlations, we calculate the diffusivity of passive\ntracers and reveal its non-trivial density dependence. The theory is in\nquantitative agreement with the lattice Boltzmann simulations and captures the\nasymmetry between pusher and puller swimmers below the transition to\nturbulence."
    },
    {
        "anchor": "Yield-stress transition in suspensions of deformable droplets: Yield-stress materials, which require a sufficiently large forcing to flow,\nare currently ill-understood theoretically. To gain insight into their yielding\ntransition, here we study numerically the rheology of a suspension of\ndeformable droplets under pressure-driven flow. We show that the suspension\ndisplays yield-stress behaviour, with the droplets remaining motionless when\nthe applied body-force is below a critical value. In the non-flowing phase,\ndroplets jam to form an amorphous structure, whereas they order in the flowing\nphase. Yielding is linked to a percolation transition in the contacts of\ndroplet-droplet overlaps, and requires suitable wetting boundary conditions and\nstrict conservation of the droplet area to exist. Close to the yielding\ntransition, we find strong oscillations in the droplet motion which closely\nresemble those found experimentally in confined colloidal glasses under flow.\nWe show that even when droplets are static the underlying solvent moves by\npermeation, so that the viscosity of the composite system is never truly\ninfinite, and, as we discuss, its precise value ceases to be a bulk material\nproperty of the system.",
        "positive": "Molecular Origin of Limiting Shear Stress of Elastohydrodynamic\n  Lubrication Oil Film Studied by Molecular Dynamics: All-atom molecular dynamics simulations of an elastohydrodynamic lubrication\noil film are performed to study the effect of pressure. Fluid molecules of\nn-hexane are confined between two solid plates under a constant normal force of\n0.1--8.0 GPa. Traction simulations are performed by applying relative sliding\nmotion to the solid plates. A transition in the traction behavior is observed\naround 0.5--2.0 GPa, which corresponds to the viscoelastic region to the\nplastic--elastic region, which are experimentally observed. This phase\ntransition is related to the suppression of the fluctuation in molecular\nmotion."
    },
    {
        "anchor": "Statistics of polymer adsorption under shear flow: Using non-equilibrium Brownian dynamics computer simulations, we have\ninvestigated the steady state statistics of a polymer chain under three\ndifferent shear environments: i) linear shear flow in the bulk (no walls), ii)\nshear vorticity normal to the adsorbing wall, iii) shear gradient normal to the\nadsorbing wall. The statistical distribution of the chain end-to-end distance\nand its orientational angles are calculated within our monomer-resolved\ncomputer simulations. Over a wide range of shear rates, this distribution can\nbe mapped onto a simple theoretical finite-extensible-nonlinear-elastic\ndumbbell model with fitted anisotropic effective spring constants. The tails of\nthe angular distribution functions are consistent with scaling predictions\nborrowed from the bulk dumbbell model. Finally, the frequency of the\ncharacteristic periodic tumbling motion has been investigated by simulation as\nwell and was found to be sublinear with the shear rate for the three set-ups,\nwhich extends earlier results done in experiments and simulations for free and\ntethered polymer molecules without adsorption.",
        "positive": "Casimir forces in modulated systems: For the first time we present analytical results for the contribution of\nelectromagnetic fluctuations into thermodynamic properties of modulated\nsystems, like cholesteric or smectic liquid crystalline films. In the case of\nsmall dielectric anisotropy we have derived explicit analytical expressions for\nthe chemical potential of such systems. Two limiting cases were specifically\nconsidered: (i) the Van der Waals (VdW) limit, i.e., in the case when the\nretardation of the electromagnetic interactions can be neglected; and (ii) the\nCasimir limit, i.e. when the effects of retardation becomes considerable. It\nwas shown that in the Casimir limit, the film chemical potential oscillates\nwith the thickness of the film. This non-monotonic dependence of the chemical\npotential on the film thickness can lead to step-wise wetting phenomena,\nsurface anchoring reorientation and other important effects. Applications of\nthe results may concern the various systems in soft matter or condensed matter\nphysics with multilayer or modulated structures."
    },
    {
        "anchor": "Temperature Dependence of Damping and Frequency Shifts of the Scissors\n  Mode of a trapped Bose-Einstein Condensate: We have studied the properties of the scissors mode of a trapped\nBose-Einstein condensate of $^{87}$Rb atoms at finite temperature. We measured\na significant shift in the frequency of the mode below the hydrodynamic limit\nand a strong dependence of the damping rate as the temperature increased. We\ncompared our damping rate results to recent theoretical calculations for other\nobserved collective modes finding a fair agreement. From the frequency\nmeasurements we deduce the moment of inertia of the gas and show that it is\nquenched below the transition point, because of the superfluid nature of the\ncondensed gas.",
        "positive": "Waterlike anomalies in hard core-soft shell nanoparticles using a\n  effective potential approach: pinned vs adsorbed polymers: In this work, a two dimensional system of polymer grafted nanoparticles is\nanalyzed using large-scale Langevin Dymanics simulations. Effective\ncore-softened potentials were obtained for two cases: one where the polymers\nare free to rotate around the nanoparticle core and a second where the polymers\nare fixed, with a $45^\\circ$ angle between them. The use of effective\ncore-softened potentials allow us to explore the complete system phase space.\nIn this way, the $PT$, $T\\rho$ and $P\\rho$ phase diagrams for each potential\nwere obtained, with all fluid and solid phases. The phase boundaries were\ndefined analyzing the specific heat at constant pressure, the system mean\nsquare displacement, the radial distribution function and the discontinuities\nin the density-pressure phase diagram. Also, due the competition in the system\nwe have observed the presence of waterlike anomalies, such as the temperature\nof maximum density - in addition with a tendency of the TMD to move to lower\ntemperatures (negative slope)- and the diffusion anomaly. It was observed\ndifferent morphologies (stripes, honeycomb, amorphous) for each nanoparticle.\nWe observed that for the fixed polymers case the waterlike anomalies are\noriginated by the competition between the potential characteristic length\nscales, while for the free to rotate case the anomalies arises due a smaller\nregion of stability in the phase diagram and no competition between the scales\nwas observed."
    },
    {
        "anchor": "Interactions in Active Colloids: The past two decades have seen a remarkable progress in the development of\nsynthetic colloidal agents which are capable of creating directed motion in an\nunbiased environment at the microscale. These self-propelling particles are\noften praised for their enormous potential to self-organize into dynamic\nnonequilibrium structures such as living clusters, synchronized super-rotor\nstructures or self-propelling molecules featuring a complexity which is rarely\nfound outside of the living world. However, the precise mechanisms underlying\nthe formation and dynamics of many of these structures are still barely\nunderstood, which is likely to hinge on the gaps in our understanding of how\nactive colloids interact. In particular, besides showing comparatively\nshort-ranged interactions which are well known from passive colloids (Van der\nWaals, electrostatic etc.), active colloids show novel hydrodynamic\ninteractions as well as phoretic and substrate-mediated \"osmotic\"\ncross-interactions which hinge on the action of the phoretic field gradients\nwhich are induced by the colloids on other colloids in the system. The present\narticle discusses the complexity and the intriguing properties of these\ninteractions which in general are long-ranged, non-instantaneous, non-pairwise\nand non-reciprocal and which may serve as key ingredients for the design of\nfuture nonequilibrium colloidal materials. Besides providing a brief overview\non the state of the art of our understanding of these interactions a key aim of\nthis review is to emphasize open key questions and corresponding open\nchallenges.",
        "positive": "Enthalpy recovery in semicrystalline polymers: Constitutive equations are derived for enthalpy recovery in polymeric glasses\nafter thermal jumps. The model is based on the theory of cooperative relaxation\nin a version of the trapping concept. It is demonstrated that some critical\ntemperature and some critical degree of crystallinity exist above which the\nenergy landscape becomes homogeneous and structural relaxation ceases."
    },
    {
        "anchor": "Controlling colloidal sedimentation using time dependent shear: Employing a recently developed dynamical density functional theory we study\nthe response of a colloidal sediment above a wall to shear, demonstrating the\ntime dependent changes of the density distribution and its center-of-mass after\nswitching shear either on or off and under oscillatory shear. Following the\nonset of steady shear we identify two dynamical mechanisms, distinguished by\ntheir timescales. Shortly after the onset, a transient enhancement of the\npacking structure at the wall reflects the self-organization into lanes. On a\nmuch longer timescale these effects are transmitted to the bulk, leading to\nmigration away from the wall and an increase in the center-of-mass. Under\noscillatory shear flow the center-of-mass enters a stationary state,\nreminiscent of a driven damped oscillator.",
        "positive": "Influence of bidisperse self-assembled monolayer structure on the slip\n  boundary condition of thin polymer films: Alkylsilane self-assembled monolayers (SAMs) are often used as model\nsubstrates for their ease of preparation and hydrophobic properties. We have\nobserved that these atomically smooth monolayers also provide a slip boundary\ncondition for dewetting films composed of unentangled polymers. This slip\nlength, an indirect measure of the friction between a given liquid and\ndifferent solids, is switchable and can be increased [Fetzer et al., Phys. Rev.\nLett. 2005; B\\\"aumchen et al. J. Phys.: Cond. Matt. 2012] if the alkyl chain\nlength is changed from 18 to 12 backbone carbons, for example. Typically, this\nchange in boundary condition is affected in a quantized way, using one or the\nother alkyl chain length, thus obtaining one or the other slip length. Here, we\npresent results in which this SAM structure is changed in a continuous way. We\nprepare SAMs containing bidisperse mixed SAMs of alkyl silanes, with the\ncomposition as a control parameter. We find that all the mixed SAMs we\ninvestigated show an enhanced slip boundary condition as compared to the\nsingle-component SAMs. The slip boundary condition is accessed using optical\nand atomic force microscopy, and we describe these observations in the context\nof X-ray reflectivity measurements. The slip length, varying over nearly two\norders of magnitude, of identical polymer melts on chemically similar SAMs is\nfound to correlate with the density of exposed alkyl chains. Our results\ndemonstrate the importance of a well characterized solid/liquid pair, down to\nthe angstrom level, when discussing friction between a liquid and a solid."
    },
    {
        "anchor": "Collapse of quasi-two-dimensional wet granular columns: This paper deals with the experimental characterization of the collapse of\nwet granular columns in the pendular state, with the purpose of collecting data\non triggering and jamming phenomena in wet granular media. The final deposit\nshape and the runout dynamics were studied for samples of glass beads, varying\nparticle diameter, liquid surface tension, and liquid amount. We show how the\nrunout distance decreases with increasing water amount (reaching a plateau for\n$w>1 \\%$) and increases with increasing Bond number, while the top and toe\nangles and the final deposit height increase with increasing water amount and\ndecrease with decreasing Bond number. Dimensional analysis allowed to discuss\npossible scalings for the runout length and the top and toe angles: a\nsatisfying scaling was found, based on the combination of Bond number and\nliquid amount.",
        "positive": "Bistability and hysteresis in tilted sandpiles: We show that tilting a model sandpile that has dynamic disorder leads to\nbistability and hysteresis at the angle of repose. Also the distribution of\n{\\it local slopes} shows an interesting dependence on the amount of tilt -\nweakly tilted sandpiles retain the quasi-continuous distributions of the steady\nstate, while large tilt makes the distribution more discrete, with local slopes\nclustered round particular values. These observations are used to explain\nrecent experimental results on avalanche shapes; we give a theoretical\nframework in terms of directed percolation."
    },
    {
        "anchor": "Conformational Control of Exciton-Polariton Physics in Metal -\n  Poly(9,9-dioctylfluorene) - Metal Cavities: Control is exerted over the exciton-polariton physics in metal -\nPoly(9,9-dioctyl fluorene) - metal microcavities via conformational changes to\nthe polymer backbone. Using thin-film samples containing increasing fractions\nof $\\beta$-phase chain segments, a systematic study is reported for the mode\ncharacteristics and resulting light emission properties of cavities containing\ntwo distinct exciton sub-populations within the same semiconductor. Ultrastrong\ncoupling for disordered glassy-phase excitons is observed from angle-resolved\nreflectivity measurements, with Rabi splitting energies in excess of 1.05 eV\n(more than 30% of the exciton transition energy) for both TE- and TM-polarized\nlight. A splitting of the lower polariton branch is then induced via\nintroduction of $\\beta$-phase excitons and increases with their growing\nfraction. In all cases, the photoluminescence emanates from the lowermost\npolariton branch, allowing conformational control to be exerted over the\nemission energy and its angular variation. Dispersion-free cavities with highly\nsaturated blue-violet emission are thus enabled. Experimental results are\ndiscussed in terms of the full Hopfield Hamiltonian generalized to the case of\ntwo exciton oscillators. The importance of taking account of the molecular\ncharacteristics of the semiconductor for an accurate description of its strong\ncoupling behaviour is directly considered, in specific relation to the role of\nthe vibronic structure.",
        "positive": "Theory of self-coacervation in semi-dilute and concentrated zwitterionic\n  polymer solutions: Based on the random phase approximation, we develop a molecular theory of\nself-coacervation in zwitterionic polymer solutions. We show that the interplay\nbetween the volume interactions of the monomeric units and electrostatic\ncorrelations of charged groups on a polymer backbone can result in\nliquid-liquid phase separation (self-coacervation). We analyse the behavior of\nthe coacervate phase polymer concentration depending on the electrostatic\ninteraction strength -- the ratio of the Bjerrum length to the bond length of\nthe chain. We establish that in a wide range of polymer concentration values --\nfrom a semi-dilute to a rather concentrated solution -- the chain connectivity\nand excluded volume interaction of the monomeric units have an extremely weak\neffect on the contribution of the electrostatic interactions of the dipolar\nmonomeric units to the total free energy. We show that for rather weak\nelectrostatic interactions, the electrostatic correlations manifest themselves\nas Keesom interactions of point-like freely rotating dipoles (Keesom regime),\nwhile in the region of strong electrostatic interactions the electrostatic free\nenergy is described by the Debye-H{\\\"u}ckel limiting law (Debye regime). We\nshow that for real zwitterionic coacervates the Keesom regime is realized only\nfor sufficiently small polymer concentrations of the coacervate phase, while\nthe Debye regime is approximately realized for rather dense coacervates. Using\nthe mean-field variant of the density functional theory, we calculate the\nsurface tension (surface free energy) of the $\"$coacervate-solvent$\"$ interface\nas a function of the bulk polymer concentration. Obtained results can be used\nto estimate the parameters of the polymer chains needed for practical\napplications such as drug encapsulation and delivery, as well as the design of\nadhesive materials."
    },
    {
        "anchor": "Dynamic coupling between a multistable defect pattern and flow in\n  nematic liquid crystals confined in a porous medium: When a nematic liquid crystal is confined in a porous medium with strong\nanchoring conditions, topological defects, called disclinations, are stably\nformed with numerous possible configurations. Since the energy barriers between\nthem are large enough, the system shows multistability. Our lattice Boltzmann\nsimulations demonstrate dynamic couplings between the multistable defect\npattern and the flow in a regular porous matrix. At sufficiently low flow\nspeed, the topological defects are pinned at the quiescent positions. As the\nflow speed is increased, the defects show cyclic motions and nonlinear\nrheological properties, which depend on whether or not they are topologically\nconstrained in the porous networks. In addition, we discovered that the defect\npattern can be controlled by controlling the flow. Thus, the flow path is\nrecorded in the porous channels owing to the multistability of the defect\npatterns.",
        "positive": "Numerical Tests of Constitutive Laws for Dense Granular Flows: We numerically and theoretically study macroscopic properties of dense,\nsheared granular materials. In this process we first introduce an invariance in\nNewton's equations, explain how it leads to Bagnold's scaling, and discuss how\nit relates to the dynamics of granular temperature. Next we implement numerical\nsimulations of granular materials in two different geometries-- simple shear\nand flow down an incline-- and show that measurements can be extrapolated from\none geometry to the other. Then we observe non-affine rearrangements of\nclusters of grains in response to shear strain and show that fundamental\nobservations, which served as a basis for the Shear Transformation Zone (STZ)\ntheory of amorphous solids, can be reproduced in granular materials. Finally we\npresent constitutive equations for granular materials, based on the dynamics of\ngranular temperature and STZ theory, and show that they match remarkably well\nwith our numerical data from both geometries."
    },
    {
        "anchor": "Crystal polymorph selection mechanism of hard spheres hidden in the\n  fluid: Nucleation plays a critical role in the birth of crystals and is associated\nwith a vast array of phenomena such as protein crystallization and ice\nformation in clouds. Despite numerous experimental and theoretical studies,\nmany aspects of the nucleation process like the polymorph selection mechanism\nin the early stages are far from being understood. Here, we show that the\nexcess of particles in a face-centred-cubic (fcc)-like environment with respect\nto those in a hexagonal-close-packed (hcp)-like environment in a crystal\nnucleus of hard spheres as observed in simulations and experiments can be\nexplained by the higher order structure in the fluid phase. We show using both\nsimulations and experiments that, in the metastable fluid phase, fivefold\nsymmetry clusters -- pentagonal bipyramids (PBs) -- known to be inhibitors of\ncrystal nucleation, transform into a different cluster -- Siamese dodecahedra\n(SDs). Due to their geometry, these clusters form a bridge between the fivefold\nsymmetric fluid and the fcc crystal, thus lowering its interfacial free energy\nwith respect to the hcp crystal, and shedding new light on the polymorph\nselection mechanism.",
        "positive": "Generic instabilities in a fluid membrane coupled to a thin layer of\n  ordered active polar fluid: We develop an effective two-dimensional coarse-grained description for the\ncoupled system of a planar fluid membrane anchored to a thin layer of polar\nordered active fluid below. The macroscopic orientation of the active fluid\nlayer is assumed to be perpendicular to the attached membrane. We demonstrate\nthat {\\em activity} or nonequilibrium drive of the active fluid makes such a\nsystem generically linearly unstable for either signature of a model parameter\n$\\Delta\\mu$ that characterises the strength of activity. Depending upon\nboundary conditions and within a range of the model parameters, underdamped\npropagating waves may be present in our model. We discuss the phenomenological\nsignificance of our results."
    },
    {
        "anchor": "Structural phase transitions of vortex matter in an optical lattice: We consider the vortex structure of a rapidly rotating trapped atomic\nBose-Einstein condensate in the presence of a co-rotating periodic optical\nlattice potential. We observe a rich variety of structural phases which reflect\nthe interplay of the vortex-vortex and vortex-lattice interactions. The lattice\nstructure is very sensitive to the ratio of vortices to pinning sites and we\nobserve structural phase transitions and domain formation as this ratio is\nvaried.",
        "positive": "Effect of topology on the statics and dynamics of a polymer chain at the\n  fluid-fluid interface: a molecular dynamics simulation study: The effect of chain topology on the statics and dynamics of chain at the\ninterface of two immiscible fluids is studied by means of molecular dynamics\nsimulations. For three topologically different chains, namely, linear, ring,\nand trefoil-knot of same molecular weight the effect of varying both\npolymer--fluid and fluid--fluid interaction nature on the width of the fluid\ninterface, chain conformation, shape, and chain dynamics. For sharp-interface\nbinary-fluid system, the interface width is insensitive to both topology and\npolymer-fluid interaction nature, while a weak non-monotonic variation is seen\nfor weak-interface system. Chain extension normal to the interface plane is\nsignificantly affected by the topology with trefoil-knot chain, due to the\nadditional constraint, has the largest value compared to both linear and ring\npolymers. Instantaneous shapes are also quantified through shape parameters.\nFurthermore, it is observed that the qualitative behavior of center of mass\nmean-square displacement (MSD) is independent of topology, i.e., all the chain\ntypes show same diffusion exponent $\\alpha~(\\approx 1)$. However, the\nself-diffusion constant depends on the topology and it is largest for\ntrefoil-knot chain. An interesting observation pertaining the early time\nbehavior of monomeric-MSD is that, within the sub-diffusive regime, the values\nof $\\alpha$ for different parameters (independent of topology) are grouped into\ntwo distinct ranges (0.52--0.59 and 0.62--0.67) which is related to the\ndifferent chain conformation for polymer-fluid interaction range below and\nabove a threshold value equal to that of the self-interaction of the pure fluid\nphase."
    },
    {
        "anchor": "Concentration dependence of diffusion-limited reaction rates and its\n  consequences: Diffusion-limited association reactions are ubiquitous in nature. They are\nparticularly important for biological reactions, where the reaction rates are\noften determined by the diffusive transport of the molecules on two-dimensional\nsurfaces, such as the cell membrane. The peculiarities of diffusion on\ntwo-dimensional surfaces may lead to nontrivial reaction kinetics, such as\nconcentration dependent rate of association between two molecules. However,\ntraditionally, the kinetics of biomolecular association reactions has been\nmodeled using the law of mass action, which assumes that the rate of reaction\nis a concentration independent constant. In this paper, using multiscale\nmolecular simulation, we investigate the concentration dependence of\ndiffusion-limited association reactions on 2D surfaces. In particular, we\nquantify the influence of short-ranged pair interactions on the concentration\ndependence of the reaction rates and codify it in an empirical law. Using this\nlaw in a chemical kinetic model, we find that the the steady state behaviors of\nsimple chemical systems are drastically modified by the presence of\nconcentration dependent rates. In particular, we find that it leads to\nsuppression of intrinsic noise in dimerization reaction and destabilizes robust\noscillation in Lotka-Volterra predator-prey systems. In fact, we see a\ntransition from robust to fine-tuned behavior in the latter. In addition, we\nshow that concentration dependent reaction rates arise naturally in stochastic\npredator-prey systems due to intrinsic noise. We comment on the consequences of\nthese results and discuss their implications in the modeling of complex\nchemical and biological systems. In particular, we comment on the range of\nvalidity of the law of mass action, which is a staple in all theoretical\nmodeling of these systems.",
        "positive": "Characterizing Aqueous Foams by In-situ Viscosity Measurement in a Foam\n  Column: Foam characterization is essential in many applications of foams, such as\ncleaning, food processing, cosmetics, and oil production, due to these\napplications diversified requirements. The standard characterization method,\nthe foam column test, cannot provide sufficient information for in-depth\nstudies. Hence, there have been many studies that incorporated different\ncharacterization methods into the standard test. It should be enlightening and\nfeasible to measure the foam viscosity, which is both of practical and\nfundamental interest, during the foam column test, but it has never been done\nbefore. Here, we demonstrate a method to characterize aqueous foams and their\naging behaviors with simultaneous measurement of foam viscosity and foam\nheight. Using a vibration viscometer, we integrate foam column experiments with\nin-situ foam viscosity measurements. We studied the correlation among the foam\nstructure, foam height, and foam viscosity during the foam decay process. We\nfound a drastic decrease in foam viscosity in the early foam decay while the\nfoam height remained unchanged, which is explained by coarsening. This method\nis much more sensitive and time-efficient than conventional foam-height-based\nmethods by comparing the half-life. This method successfully characterizes the\nstability of foams made of various combinations of surfactants and gases."
    },
    {
        "anchor": "Towards automation of the polyol process for the synthesis of silver\n  nanoparticles: Metal nanoparticles have a substantial impact across different fields of\nscience, such as photochemistry, energy conversion, and medicine. Among the\ncommonly used nanoparticles, silver nanoparticles are of special interest due\nto their antibacterial properties and applications in sensing and catalysis.\nHowever, many of the methods used to synthesize silver nanoparticles often do\nnot result in well-defined products, the main obstacles being high\npolydispersity or a lack of particle size tunability. We describe an automated\napproach to on-demand synthesis of adjustable particles with mean radii of 3\nand 5 nm using the polyol route. The polyol process is a promising route for\nsilver nanoparticles e.g., to be used as reference materials. We characterised\nthe as-synthesized nanoparticles using small-angle X-ray scattering, dynamic\nlight scattering and further methods, showing that automated synthesis can\nyield colloids with reproducible and tuneable properties.",
        "positive": "Relationship between bond-breakage correlations and four-point\n  correlations in heterogeneous glassy dynamics: Configuration changes and\n  vibration modes: We investigate the dynamic heterogeneities of glassy particle systems in the\ntheoretical schemes of bond breakage and four-point correlation functions. In\nthe bond-breakage scheme, we introduce the structure factor S_b(q,t) and the\nsusceptibility chi_b(t) to detect the spatial correlations of configuration\nchanges. Here chi_b(t) attains a maximum at t =t_b^max as a function of time t,\nwhere the fraction of the particles with broken bonds phi_b(t)$ is about 1/2.\nIn the four-point scheme, treating the structure factor S_4(q,t) and the\nsusceptibility chi_4(t), we detect superpositions of the heterogeneity of bond\nbreakage and that of thermal low-frequency vibration modes. While the former\ngrows slowly, the latter emerges quickly to exhibit complex space-time\nbehavior. In two dimensions, the vibration modes extending over the system\nyield significant contributions to the four-point correlations, which depend on\nthe system size logarithmically. A maximum of chi_4(t) is attained at t=\nt_4^max, where these two contributions become of the same order. As a result,\nt_4^max is considerably shorter than t_b^max."
    },
    {
        "anchor": "Impact of boundaries on velocity profiles in bubble rafts: Under conditions of sufficiently slow flow, foams, colloids, granular matter,\nand various pastes have been observed to exhibit shear localization, i.e.\nregions of flow coexisting with regions of solid-like behavior. The details of\nsuch shear localization can vary depending on the system being studied. A\nnumber of the systems of interest are confined so as to be quasi-two\ndimensional, and an important issue in these systems is the role of the\nconfining boundaries. For foams, three basic systems have been studied with\nvery different boundary conditions: Hele-Shaw cells (bubbles confined between\ntwo solid plates); bubble rafts (a single layer of bubbles freely floating on a\nsurface of water); and confined bubble rafts (bubbles confined between the\nsurface of water below and a glass plate on top). Often, it is assumed that the\nimpact of the boundaries is not significant in the ``quasi-static limit'', i.e.\nwhen externally imposed rates of strain are sufficiently smaller than internal\nkinematic relaxation times. In this paper, we directly test this assumption for\nrates of strain ranging from $10^{-3}$ to $10^{-2} {\\rm s^{-1}}$. This\ncorresponds to the quoted quasi-static limit in a number of previous\nexperiments. It is found that the top plate dramatically alters both the\nvelocity profile and the distribution of nonlinear rearrangements, even at\nthese slow rates of strain.",
        "positive": "Encapsulation by Janus spheroids: The micro/nano encapsulation technology has acquired considerable attention\nin the fields of drug delivery, biomaterial engineering, and materials science.\nBased on recent advances in chemical particle synthesis, we propose a primitive\nmodel of an encapsulation system produced by the self-assembly of Janus oblate\nspheroids, particles with oblate spheroidal bodies and two hemi-surfaces coded\nwith dissimilar chemical properties. Using Monte Carlo simulation, we\ninvestigate the encapsulation system with spherical particles as encapsulated\nguests, for different densities. We study the anisotropic effect due to the\nencapsulating agent's geometric shape and chemical composition on the\nencapsulation morphology and efficiency. Given the relatively high\nencapsulation efficiency we find from the simulations, we believe that this\nmethod of encapsulation has potential practical value."
    },
    {
        "anchor": "Molecular Dynamics in grafted layers of poly(dimethylsiloxane) (PDMS): Dielectric relaxation spectroscopy 10^-1 Hz to 10^6 Hz) is employed to study\nthe molecular dynamics of poly(dimethylsiloxane) (PDMS, Mw=1.7 10^5 g/mol and\nMw=9.6 10^4 g/mol as grafted films with thicknesses d below and above the\nradius of gyration Rg. For d smaller than Rg the molecular dynamics becomes\nfaster by up to three orders of magnitude with respect to the bulk resulting in\na pronounced decrease of the Vogel temperature T0 and hence the calorimetric\nglass transition temperature Tg. For d larger than Rg the molecular dynamics is\ncomparable to that of the bulk melt. The results are interpreted in terms of a\nchain confinement effect and compared with the findings for low molecular eight\nglass forming liquids contained in nanoporous glasses and zeolites.\nCrystallization effects - well known for PDMS - are observed for films of\nthicknesses above and below Rg.",
        "positive": "Thermal Molecular Focusing: Tunable Cross Effect of Phoresis and\n  Advection: The control of solute fluxes through either microscopic phoresis or\nhydrodynamic advection is a fundamental way to transport molecules, which are\nubiquitously present in nature and technology. We study the transport of large\nsolute such as DNA driven by a time-dependent thermal field in a polymer\nsolution. Heat propagation of a single heat spot moving back and forth gives\nrise to the molecular focusing of DNA with frequency-tunable control. We\ndeveloped a theoretical model, where heat conduction, viscoelastic expansion of\nwalls, and the viscosity gradient of a smaller solute are coupled, and that can\nexplain the underlying hydrodynamic focusing and its interplay with phoretic\ntransports. This cross effect may allow one to design a unique miniaturized\npump in microfluidics."
    },
    {
        "anchor": "Electrokinetic and hydrodynamic properties of charged-particles systems:\n  From small electrolyte ions to large colloids: Dynamic processes in dispersions of charged spherical particles are of\nimportance both in fundamental science, and in technical and bio-medical\napplications. There exists a large variety of charged-particles systems,\nranging from nanometer-sized electrolyte ions to micron-sized charge-stabilized\ncolloids. We review recent advances in theoretical methods for the calculation\nof linear transport coefficients in concentrated particulate systems, with the\nfocus on hydrodynamic interactions and electrokinetic effects. Considered\ntransport properties are the dispersion viscosity, self- and collective\ndiffusion coefficients, sedimentation coefficients, and electrophoretic\nmobilities and conductivities of ionic particle species in an external electric\nfield. Advances by our group are also discussed, including a novel\nmode-coupling-theory method for conduction-diffusion and viscoelastic\nproperties of strong electrolyte solutions. Furthermore, results are presented\nfor dispersions of solvent-permeable particles, and particles with non-zero\nhydrodynamic surface slip. The concentration-dependent swelling of ionic\nmicrogels is discussed, as well as a far-reaching dynamic scaling behavior\nrelating colloidal long- to short-time dynamics.",
        "positive": "Nuclear magnetic resonance measurements reveal the origin of the Debye\n  process in monohydroxy alcohols: Monohydroxy alcohols show a structural relaxation and at longer time scales a\nDebye-type dielectric peak. From spin-lattice relaxation experiments using\ndifferent nuclear probes an intermediate, slower-than-structural dynamics is\nidentified for n-butanol. Based on these findings and on diffusion\nmeasurements, a model of self-restructuring, transient chains is proposed. The\nmodel is demonstrated to explain consistently the so far puzzling observations\nmade for this class of hydrogen-bonded glass forming liquids."
    },
    {
        "anchor": "Quasistatic rheology of soft cellular systems using Cellular Potts Model: Soft cellular systems, such as foams or biological tissues, exhibit highly\ncomplex rheological properties, even in the quasistatic regime, that numerical\nmodeling can help to apprehend. We present a numerical implementation of\nquasistatic strain within the widely used cellular Potts model. The accuracy of\nthe method is tested by simulating the quasistatic strain 2D dry foams, both\nordered and disordered. The implementation of quasistatic strain in CPM allows\nthe investigation of sophisticated interplays between stress-strain\nrelationship and structural changes that take place in cellular systems.",
        "positive": "Screening, Hyperuniformity, and Instability in the Sedimentation of\n  Irregular Objects: We study the overdamped sedimentation of non-Brownian objects of irregular\nshape using fluctuating hydrodynamics. The anisotropic response of the objects\nto flow, caused by their tendency to align with gravity, directly suppresses\nconcentration and velocity fluctuations. This allows the suspension to avoid\nthe anomalous fluctuations predicted for suspensions of symmetric spheroids.\nThe suppression of concentration fluctuations leads to a correlated,\nhyperuniform structure. For certain object shapes, the anisotropic response may\nact in the opposite direction, destabilizing uniform sedimentation."
    },
    {
        "anchor": "Polymer Release out of a Spherical Vesicle through a Pore: Translocation of a polymer out of curved surface or membrane is studied via\nmean first passage time approach. Membrane curvature gives rise to a constraint\non polymer conformation, which effectively drives the polymer to the outside of\nmembrane where the available volume of polymer conformational fluctuation is\nlarger. Considering a polymer release out of spherical vesicle, polymer\ntranslocation time $\\tau$ is changed to the scaling behavior $\\tau\\sim L^2$ for\n$R<R_G$, from $\\tau\\sim L^3$ for $R\\gg R_G$, where $L$ is the polymer contour\nlength and $R$, $R_G$ are vesicle radius and polymer radius of gyration\nrespectively. Also the polymer capture into a spherical budd is studied and\npossible apparatus for easy capture is suggested.",
        "positive": "Phase transition or Maxwell's demon in Granular gas?: Dynamics of vibro-fluidised granular gas is investigated experimentally using\nthe transfer of grains from a compartment through a horizontal slit at a given\nheight h . It is demonstrated that the transfer rate j varies linearly with the\ngrain number N in the box when N remains small; however j(N) becomes strongly\nnon linear as soon as the number n of layers is larger than 0.3; dj/dN becomes\nnegative for n>0.4.It is found also that the maximum of j(N) increases slightly\nwith the acceleration af_ of the vibration which excites the granular gas.\nUsing dynamical system theory, dynamics equations are written, and a critical\nbifurcation is found, which explains the existence of a condensation and of a\nphase transition. This explains how the pseudo \" Maxwell's demon\" works in\ngranular gases. This experiments contradicts recent modeling . Pacs # : 5.40 ;\n45.70 ; 62.20 ; 83.70.Fn"
    },
    {
        "anchor": "Modulation Mechanism of Ionic Transport through Short Nanopores by\n  Charged Exterior Surfaces: Short nanopores have various applications in biosensing, desalination, and\nenergy conversion. Here, the modulation of charged exterior surfaces on ionic\ntransport is investigated through simulations with sub-200 nm long nanopores\nunder applied voltages. Detailed analysis of ionic current, electric field\nstrength, and fluid flow inside and outside nanopores reveals that charged\nexterior surfaces can increase ionic conductance by increasing both the\nconcentration and migration speed of charge carriers. The electric double\nlayers near charged exterior surfaces provide an ion pool and an additional\npassageway for counterions, which lead to enhanced exterior surface conductance\nand ionic concentrations at pore entrances and inside the nanopore. We also\nreport that charges on the membrane surfaces increase electric field strengths\ninside nanopores. The effective width of a ring with surface charges placed at\npore entrances (Lcs) is considered as well by studying the dependence of the\ncurrent on Lcs. We find a linear relationship between the effective Lcs and the\nsurface charge density and voltage, and an inverse relationship between the\ngeometrical pore length and salt concentration. Our results elucidate the\nmodulation mechanism of charged exterior surfaces on ionic transport through\nshort nanopores, which is important for the design and fabrication of porous\nmembranes.",
        "positive": "Symmetry-specific characterization of bond orientation order in\n  DNA-assembled nanoparticle lattices: Bond-orientational order in DNA-assembled nanoparticle lattices is explored\nwith the help of recently introduced Symmetry-specific Bond Order Parameters\n(SymBOPs). This approach provides a more sensitive analysis of local order than\ntraditional scalar Bond Order Parameters, facilitating the identification of\ncoherent domains at the single bond level. The present study expands the method\ninitially developed for assemblies of anisotropic particles to the isotropic\nones or cases where particle orientation information is unavailable. The SymBOP\nanalysis was applied to experiments on DNA-frame-based assembly of nanoparticle\nlattices. It proved highly sensitive in identifying coherent crystalline\ndomains with different orientations, as well as detecting topological defects,\nsuch as dislocations. Furthermore, the analysis distinguishes individual\nsublattices within a single crystalline domain, such as pair of\ninterpenetrating FCC lattices within a cubic diamond. The results underscore\nthe versatility and robustness of SymBOPs in characterizing ordering phenomena,\nmaking them valuable tools for investigating structural properties in various\nsystems."
    },
    {
        "anchor": "Generalized entropy theory of glass-formation in fully flexible polymer\n  melts: The generalized entropy theory (GET) offers many insights into how molecular\nparameters influence polymer glass-formation. Given the fact that chain\nrigidity often plays a critical role in understanding the glass-formation of\npolymer materials, the GET was originally developed based on models of\nsemiflexible chains. Consequently, all previous calculations within the GET\nconsidered polymers with some degree of chain rigidity. Motivated by unexpected\nresults from computer simulations of fully flexible polymer melts concerning\nthe dependence of thermodynamic and dynamic properties on the cohesive\ninteraction strength ($\\epsilon$), the present paper employs the GET to explore\nthe influence of $\\epsilon$ on glass-formation in models of polymer melts with\na vanishing bending rigidity, i.e., fully flexible polymer melts. In accord\nwith simulations, the GET for fully flexible polymer melts predicts that basic\ndimensionless thermodynamic properties (such as the thermal expansion\ncoefficient and isothermal compressibility) are universal functions of the\ntemperature scaled by $\\epsilon$ in the regime of low pressures. Similar\nscaling behavior is also found for the configurational entropy density in the\nGET for fully flexible polymer melts. Moreover, we find that the characteristic\ntemperatures of glass-formation increase linearly with $\\epsilon$ and that the\nfragility is independent of $\\epsilon$ in fully flexible polymer melts,\npredictions that are again consistent with simulations of glass-forming polymer\nmelts composed of fully flexible chains. Beyond an explanation of these general\ntrends observed in simulations, the GET for fully flexible polymer melts\npredicts the presence of a positive residual configurational entropy at low\ntemperatures, indicating a return to Arrhenius relaxation in the low\ntemperature glassy state.",
        "positive": "Dissipative dynamics of a kink state in a Bose-condensed gas: We develop a theory of dissipative dynamics of a kink state in a\nfinite-temperature Bose-condensed gas. We find that due to the interaction with\nthe thermal cloud the kink state accelerates towards the velocity of sound and\ncontinuously transforms to the ground-state condensate. We calculate the\nlife-time of a kink state in a trapped gas and discuss possible experimental\nimplications."
    },
    {
        "anchor": "Yield drag in a two-dimensional foam flow around a circular obstacle:\n  Effect of liquid fraction: We study the two-dimensional flow of foams around a circular obstacle within\na long channel. In experiments, we confine the foam between liquid and glass\nsurfaces. In simulations, we use a deterministic software, the Surface Evolver,\nfor bubble details and a stochastic one, the extended Potts model, for\nstatistics. We adopt a coherent definition of liquid fraction for all studied\nsystems. We vary it in both experiments and simulations, and determine the\nyield drag of the foam, that is, the force exerted on the obstacle by the foam\nflowing at very low velocity. We find that the yield drag is linear over a\nlarge range of the ratio of obstacle to bubble size, and is independent of the\nchannel width over a large range. Decreasing the liquid fraction, however,\nstrongly increases the yield drag; we discuss and interpret this dependence.",
        "positive": "The effects of interparticle cohesion on the collapse of granular\n  columns: The presence of interparticle cohesion can drastically change the behavior of\ngranular materials. For instance, powders are challenging to handle, and one\ncan make a sandcastle using wet grains. In this study, we report experimental\nresults for columns of model cohesive grains collapsing under their own weight\nin air and spreading on a rough horizontal surface. The effects of two\ndifferent sources of interparticle cohesion on two collapse geometries are\ncompared and rationalized in a common framework. Grains are made cohesive by\nadding a small amount of water, such that they are in the pendular state, or by\napplying a polymer coating. The effects of cohesion are reported for a\ncylindrical column that spreads unconfined axisymmetrically and a confined\nrectangular column that flows in a single direction. A dimensionless number,\ncomparing macroscopic cohesive strength to particle weight, is shown to capture\nthe effects of cohesion on the final morphology. To this end, a\ncharacterization of the cohesive strength of the granular materials is\nobtained, independent of the physical source of cohesion at the particle scale.\nSuch a framework allows for a common description of cohesive granular materials\nwith different sources of cohesion."
    },
    {
        "anchor": "Topological active matter: Active matter encompasses different nonequilibrium systems in which\nindividual constituents convert energy into non-conservative forces or motion\nat the microscale. This review provides an elementary introduction to the role\nof topology in active matter through experimentally relevant examples. Here,\nthe focus lies on topological defects and topologically protected edge modes\nwith an emphasis on the distinctive properties they acquire in active media.\nThese paradigmatic examples represent two physically distinct classes of\nphenomena whose robustness can be traced to a common mathematical origin: the\npresence of topological invariants. These invariants are typically integer\nnumbers that cannot be changed by continuous deformations of the relevant order\nparameters or physical parameters of the underlying medium. We first explain\nthe mechanisms whereby topological defects self propel and proliferate in\nactive nematics, leading to collective states which can be manipulated by\ngeometry and patterning. Possible implications for active microfluidics and\nbiological tissues are presented. We then illustrate how the propagation of\nwaves in active fluids and solids is affected by the presence of topological\ninvariants characterizing their dispersion relations. We discuss the relevance\nof these ideas for the design of robotic metamaterials and the properties of\nactive granular and colloidal systems. Open theoretical and experimental\nchallenges are presented as future research prospects.",
        "positive": "Two-dimensional core-softened model with water like properties. Study by\n  thermodynamic perturbation theory: Thermodynamic properties of the particles interacting through smooth version\nof Stell-Hemmer interaction were studied using Wertheim's thermodynamic\nperturbation theory. The temperature dependence of molar volume, heat capacity,\nisothermal compressibility and thermal expansion coefficient at constant\npressure for different number of bonding sites on particle were evaluated. The\nmodel showed water-like anomalies for all evaluated quantities, but\nthermodynamic perturbation theory does not properly predict the dependence of\nthese properties at a fixed number of bonding points."
    },
    {
        "anchor": "Spontaneous motion and deformation of a self-propelled droplet: The time evolution equation of motion and shape are derived for a\nself-propelled droplet driven by a chemical reaction. The coupling between the\nchemical reaction and motion makes an inhomogeneous concentration distribution\nas well as a surrounding flow leading to the instability of a stationary state.\nThe instability results in spontaneous motion by which the shape of the droplet\ndeforms from a sphere. We found that the self-propelled droplet is elongated\nperpendicular to the direction of motion and is characterized as a pusher.",
        "positive": "The Anomalous Yield Behavior of Fused Silica Glass: We develop a critical-state model of fused silica plasticity on the basis of\ndata mined from molecular dynamics (MD) calculations. The MD data is suggestive\nof an irreversible densification transition in volumetric compression resulting\nin permanent, or plastic, densification upon unloading. The MD data also\nreveals an evolution towards a critical state of constant volume under\npressure-shear deformation. The trend towards constant volume is from above,\nwhen the glass is overconsolidated, or from below, when it is\nunderconsolidated. We show that these characteristic behaviors are\nwell-captured by a critical state model of plasticity, where the densification\nlaw for glass takes the place of the classical consolidation law of granular\nmedia and the locus of constant volume states denotes the critical-state line.\nA salient feature of the critical-state line of fused silica, as identified\nfrom the MD data, that renders its yield behavior anomalous is that it is\nstrongly non-convex, owing to the existence of two well-differentiated phases\nat low and high pressures. We argue that this strong non-convexity of yield\nexplains the patterning that is observed in molecular dynamics calculations of\namorphous solids deforming in shear. We employ an explicit and exact rank-2\nenvelope construction to upscale the microscopic critical-state model to the\nmacroscale. Remarkably, owing to the equilibrium constraint the resulting\neffective macroscopic behavior is still characterized by a non-convex\ncritical-state line. Despite this lack of convexity, the effective macroscopic\nmodel is stable against microstructure formation and defines well-posed\nboundary-value problems."
    },
    {
        "anchor": "The role of the peptides in enzymes at the origin of live: The peptides in biosystems are homochiral polymers of L-amino acids, but\nrazemisate slowly by an active isomerization kinetics. The chemical reactions\nin biosystems are, however, reversible and what racemisates the peptides at the\nwater activity in the biosystems can ensure homochirality at a smaller\nactivity. Here we show by a thermodynamics analysis and by comprehensive\nMolecular Dynamics simulations of models of peptides, that the isomerization\nkinetics racemisates the peptides at a high water activity in agreement with\nexperimental observations of aging of peptides , but enhances homochirality at\na smaller water activity. The hydrophobic core of the peptide in an enzyme can\nensure homochirality at a low water activity, and thus the establishment of\nhomochirality at the origin of life and ageing of peptides and dead of\nbiosystems might be strongly connected.",
        "positive": "Characterizing the Interplay between Polymer Solvation and Conformation: Conformational transitions of flexible molecules, especially those driven by\nhydrophobic effects, tend to be hindered by desolvation barriers. For such\ntransitions, it is thus important to characterize and understand the interplay\nbetween solvation and conformation. Using specialized molecular simulations,\nhere we perform such a characterization for a hydrophobic polymer solvated in\nwater. We find that an external potential, which unfavorably perturbs the\npolymer hydration waters, can trigger a coil-to-globule or collapse transition,\nand that the relative stabilities of the collapsed and extended states can be\nquantified by the strength of the requisite potential. Our results also provide\nmechanistic insights into the collapse transition, highlighting that polymer\ncollapse proceeds through the formation of a sufficiently large non-polar\ncluster, and that collective water density fluctuations play an important role\nin stabilizing such a cluster. We also study the collapse of the hydrophobic\npolymer in octane, a non-polar solvent, and interestingly, we find that the\nmechanistic details of the transition are qualitatively similar to that in\nwater."
    },
    {
        "anchor": "Probing Large Deformation and Fracture Behavior of Physically Assembled\n  Gel System by Varying Polymer Concentration: Physically assembled gels have promising applications in many fields because\nof their tunable mechanical properties. Here, we report the mechanical\nproperties as a function of polymer volume fraction ($\\phi$) for a physical gel\nsystem consists of poly(styrene)-poly(isoprene)-poly(styrene) [PS-PI-PS] in\nmineral oil. The PI-block molecular weight is higher than the entanglement\nmolecular weight, which leads to the entanglement of PI-blocks at higher\n$\\phi$. The micellar microstructure for all gels results in a similar stress\nrelaxation mechanism, as captured by the superposition of stress-relaxation\nresults. Tensile testing experiments reveal a strain-rate dependence mechanical\nresponse for the entangled gels. To capture the critical energy release rate\n($\\Gamma_0$) over a range of $\\phi$, both cavitation rheology and fracture\nexperiments were performed and we obtain $\\Gamma_0\\sim\\phi^{2.0}$. The gel\nmoduli scale with the volume fraction as $\\phi^{2.39}$, where the exponent is\nlikely dictated by the change in loop-to-bridge fraction with increasing\n$\\phi$.",
        "positive": "Arrested spinodal decomposition in polymer brush collapsing in poor\n  solvent: We study the Brownian dynamics of flexible and semiflexible polymer chains\ndensely grafted on a flat substrate, upon rapid quenching of the system when\nthe quality of solvent becomes poor and chains attempt collapse into a globular\nstate. The collapse process of such a polymer brush differs from individual\nchains, both in its kinetics and its structural morphology. We find that the\nresulting collapsed brush does not form a homogeneous dense layer, in spite of\nall chain monomers equally attracting each other via a model Lennard-Jones\npotential. Instead, a very distinct inhomogeneous density distribution in the\nplane forms, with a characteristic length scale dependent on the quenching\ndepth (or equivalently, the strength of monomer attraction) and the geometric\nparameters of the brush. This structure is identical to the\nspinodal-decomposition structure, however, due to the grafting constraint we\nfind no subsequent coarsening: the established random bundling with\ncharacteristic periodicity remains as the apparently equilibrium structure. We\ncompare this finding with a recent field-theoretical model of bundling in a\nsemiflexible polymer brush."
    },
    {
        "anchor": "Discrete Boltzmann modeling of Rayleigh-Taylor instability in\n  two-component compressible flows: A discrete Boltzmann model (DBM) is proposed to probe the Rayleigh-Taylor\ninstability (RTI) in two-component compressible flows. Each species has a\nflexible specific heat ratio and is described by one discrete Boltzmann\nequation (DBE). Independent discrete velocities are adopted for the two DBEs.\nThe collision and force terms in the DBE account for the molecular collision\nand external force, respectively. Two types of force terms are exploited. In\naddition to recovering the modified Navier-Stokes equations in the hydrodynamic\nlimit, the DBM has the capability of capturing detailed nonequilibrium effects.\nFurthermore, we use the DBM to investigate the dynamic process of the RTI. The\ninvariants of tensors for nonequilibrium effects are presented and studied. For\nlow Reynolds numbers, both global nonequilibrium manifestations and the growth\nrate of the entropy of mixing show three stages (i.e., the reducing,\nincreasing, and then decreasing trends) in the evolution of the RTI. On the\nother hand, the early reducing tendency is suppressed and even eliminated for\nhigh Reynolds numbers. Relevant physical mechanisms are analyzed and discussed.",
        "positive": "Colloidal Particles at Chiral Liquid Crystal Interfaces: Colloidal particles trapped at an interface between two fluids can form a\nwide range of different structures. Replacing one of the fluid with a liquid\ncrystal increases the complexity of interactions and results in a greater range\nof possible structures. New behaviour emerges when colloidal particles interact\nwith defects in the liquid crystal phases. Here we discuss the templating of\ncolloids at a cholesteric isotropic interface."
    },
    {
        "anchor": "Disappearance of stretch-induced wrinkles of thin sheets: a study of\n  orthotropic films: A recent paper (Healey et al., J. Nonlin. Sci., 2013, 23:777-805.) predicted\nthe disappearance of the stretch-induced wrinkled pattern of thin, clamped,\nelastic sheets by numerical simulation of the F\\\"oppl-von K\\'arm\\'an equations\nextended to the finite in-plane strain regime. It has also been revealed that\nfor some aspect ratios of the rectangular domain wrinkles do not occur at all\nregardless of the applied extension. To verify these predictions we carried out\nexperiments on thin 20 micrometer thick adhesive covered), previously\nprestressed elastomer sheets with different aspect ratios under displacement\ncontrolled pull tests. On one hand the the adjustment of the material\nproperties during prestressing is highly advantageous as in targeted strain\nregime the film becomes substantially linearly elastic (which is far not the\ncase without prestress). On the other hand a significant, non-ignorable\northotropy develops during this first extension. To enable quantitative\ncomparisons we abandoned the assumption about material isotropy inherent in the\noriginal model and derived the governing equations for an orthotropic medium.\nIn this way we found good agreement between numerical simulations and\nexperimental data.\n  Analysis of the negativity of the second Piola-Kirchhoff stress tensor\nrevealed that the critical stretch for a bifurcation point at which the\nwrinkles disappear must be finite for any aspect ratio. On the contrary there\nis no such a bound for the aspect ratio as a bifurcation parameter. Physically\nthis manifests as complicated wrinkled patterns with more than one highly\nwrinkled zones on the surface in case of elongated rectangles. These\narrangements have been found both numerically and experimentally. These\nfindings also support the new, finite strain model, since the F\\\"oppl-von\nK\\'arm\\'an equations based on infinitesimal strains do not exhibit such a\nbehavior.",
        "positive": "Charging-driven coarsening and melting of a colloidal nanoparticle\n  monolayer at an ionic liquid-vacuum interface: We induce and investigate the coarsening and melting dynamics of an initially\nstatic nanoparticle colloidal monolayer at an ionic liquid-vacuum interface,\ndriven by a focused, scanning electron beam. Coarsening occurs through grain\ninterface migration and larger-scale motions such as grain rotations, often\nfacilitated by sliding dislocations. The progressive decrease in area fraction\nthat drives melting of the monolayer is explained using an electrowetting model\nwhereby particles at the interface are solvated once their accumulating charge\nrecruits sufficient counterions to subsume the particle. Subject to stochastic\nparticle removal from the monolayer, melting is recapitulated in simulations\nwith a Lennard-Jones potential. This new driving mechanism for colloidal\nsystems, whose dynamical timescales we show can be controlled with the\naccelerating voltage, opens the possibility to manipulate particle interactions\ndynamically without need to vary particle intrinsic properties or surface\ntreatments. Furthermore, the decrease in particle size availed by electron\nimaging presents opportunities to observe force and time scales in a\nlesser-explored regime intermediate between typical colloidal and molecular\nsystems."
    },
    {
        "anchor": "Critical assessment of the alleged failure of the Classical Nucleation\n  Theory at low temperatures: The Classical Nucleation Theory allegedly fails to describe the temperature\ndependence of the homogeneous crystal nucleation rates below the temperature of\nmaximum nucleation, $T_{\\mathrm{max}}$. Possible explanations for this\nsuspected breakdown have been advanced in the literature. However, the simplest\nhypothesis has never been tested, that it is a byproduct of nucleation datasets\nthat have not reached the steady-state regime. In this work, we tested this\npossibility by analyzing published nucleation data for oxide supercooled\nliquids, using only nucleation and viscosity data measured in samples of the\nsame glass batch that also have satisfied a steady-state regime test.\nFurthermore, all the uncertainty and regression confidence bands were computed\nand considered. Having this rigorous protocol, among the 6 datasets analyzed,\nwe only found weak evidence supporting the existence of the nucleation break in\n2 datasets. Our collective results thus indicate that the break at\n$T_{\\mathrm{max}}$ is not a common feature of all glass-formers.",
        "positive": "Polar molecular ordering in the Nx phase of bimesogens and enantiotopic\n  discrimination in the NMR spectra of rigid prochiral solutes: The potential of mean torque governing the orientational ordering of\nprochiral solutes in the two nematic phases (N and Nx) formed by certain\nclasses of symmetric achiral bimesogens is formulated and used for the analysis\nof existing NMR measurements on solutes of various symmetries dissolved in the\ntwo phases. Three distinct attributes of the solvent phase, namely polarity of\nthe orientational ordering, chirality of the constituent molecules and spatial\nmodulation of the local director, are identified as underlying three possible\nmechanisms for the generation of chiral asymmetry in the low temperature\nnematic phase (Nx). The role and quantitative contribution of each mechanism to\nenantiotopic discrimination in the NX phase are presented and compared with the\ncase of the conventional chiral nematic phase (N*). It is found that polar\nordering is essential for the appearance of enantiotopic discrimination in\nsmall rigid solutes dissolved in the Nx phase and that such discrimination is\nrestricted to solutes belonging to the point group symmetries $C_s$ and\n$C_{2v}$."
    },
    {
        "anchor": "Impact of charge distribution of soft layers on transient electroosmotic\n  flow of Maxwell fluids in soft nanochannels: We theoretically study transient electroosmotic flow of general Maxwell\nfluids through polyelectrolyte grafted nanochannel with a layered distribution\nof charges.\n  By applying the method of Laplace transform, we semi-analytically obtain\ntransient electroosmotic flow from Cauchy momentum equation and Maxwell\nconstitutive equation.\n  For nanochannels grafted with polyelectrolyte layers having different layered\ndistribution of charges, we study the influence of dimensionless relaxation\ntime, dimensionless polyelectrolyte layer thickness and dimensionless drag\ncoefficient on transient electroosmotic flow.\n  We present the results for some particular cases. Firstly, we unravel that\nfor the case of polyzwitterionic brush that the sum of positive and negative\nstructural charges is zero, total electroosmotic flow is non-zero. In\nparticular, depending on charge distribution within end part of polyelectrolyte\nlayers, the direction of electroosmotic flow can be reversed critically.\nSecondly, in order to quantitatively evaluate a reversal of electroosmotic flow\nfor two polyelectrolyte layers of opposite signs, we introduce a critical\nnumber ks as the ratio between layered charge densities of two polyelectrolyte\nlayers. Increasing ks allows electroosmotic flow to be reversed easily.\n  We verify that adjusting charge distributions of the layer can control\nintentionally the direction of the flows as well as strength of electroosmotic\nflow.",
        "positive": "Charge fluctuations in charge regulated systems: dependence on\n  statistical ensemble: We investigate charge regulation of nanoparticles in concentrated\nsuspensions, focusing on the effect of different statistical ensembles. We find\nthat the choice of ensemble does not affect the mean charge of nanoparticles,\nbut significantly alters the magnitude of its fluctuation. Specifically, we\ncompared the behaviors of colloidal charge fluctuations in the semi-grand\ncanonical and canonical ensembles, and identified significant differences\nbetween the two. The choice of ensemble -- whether the system is isolated or is\nin contact with a reservoir of acid and salt -- will, therefore, affect the\nKirkwood-Shumaker fluctuation-induced force inside concentrated suspensions.\nOur results emphasize the importance of selecting an appropriate ensemble that\naccurately reflects the experimental conditions when studying\nfluctuation-induced forces between polyelectrolytes, proteins, and colloidal\nparticles in concentrated suspensions."
    },
    {
        "anchor": "Theory of droplet ripening in stiffness gradients: Liquid-liquid phase separation is an important mechanism for\ncompartmentalizing the cell's cytoplasm, allowing the dynamic organization of\nthe components necessary for survival. However, it is not clear how phase\nseparation is affected by the complex viscoelastic environment inside the cell.\nHere, we study theoretically how stiffness gradients influence droplet growth\nand arrangement. We show that stiffness gradients imply concentration gradients\nin the dilute phase, which transport droplet material from stiff to soft\nregions. Consequently, droplets dissolve in the stiff region, creating a\ndissolution front. Using a mean-field theory, we predict that the front emerges\nwhere the curvature of the elasticity profile is large and that it propagates\ndiffusively. This elastic ripening can occur at much faster rates than\nclassical Ostwald ripening, thus driving the dynamics. Our work shows how\ngradients in elastic properties control the size and arrangement of droplets,\nwhich has potential applications in soft matter physics and plays a role inside\nbiological cells.",
        "positive": "How to Simulate Patchy Particles: Patchy particles is the name given to a large class of systems of mesoscopic\nparticles characterized by a repulsive core and a discrete number of\nshort-range and highly directional interaction sites. Numerical simulations\nhave contributed significantly to our understanding of the behaviour of patchy\nparticles, but, although simple in principle, advanced simulation techniques\nare often required to sample the low temperatures and long time scales\nassociated with their self-assembly behaviour. In this work we review the most\npopular simulation techniques that have been used to study patchy particles,\nwith a special focus on Monte Carlo methods. We cover many of the tools\nrequired to simulate patchy systems, from interaction potentials to biased\nmoves, cluster moves, and free energy methods. The review is complemented by an\neducationally-oriented Monte Carlo computer code that implements all the\ntechniques described in the text to simulate a well-known tetrahedral patchy\nparticle model."
    },
    {
        "anchor": "Stability analysis of kinked DNA in WLRC model: This paper has been withdrawn by the author due to a new work in\n[arXiv:0901.0456v4] which can contain the results in this paper.",
        "positive": "Oscillation patterns in active emulsion networks: We study water-in-oil emulsion droplets, running the Belousov-Zhabotinsky\nreaction, that form a new type of active matter unit. These droplets,\nstabilised by surfactants dispersed in the oil medium, are capable of internal\nchemical oscillations and also self-propulsion due to dynamic interfacial\ninstabilities that result from the chemical reactions. The chemical\noscillations can couple via the exchange of activator and inhibitor type of\nreaction intermediates across the droplets under precise conditions of\nsurfactant bilayer formation between the droplets. Here we present the\nsynchronization behaviour of networks of such chemical oscillators and show\nthat the resulting dynamics depend on the network topology. Further, we\ndemonstrate that the motion of droplets can be synchronized with the chemical\noscillations inside the droplets, leading to exciting possibilities in future\nstudies of active matter."
    },
    {
        "anchor": "Swelling thermodynamics and phase transitions of polymer gels: We present a pedagogical review of the swelling thermodynamics and phase\ntransitions of polymer gels. In particular, we discuss how features of the\nvolume phase transition of the gel's osmotic equilibrium is analogous to other\ntransitions described by mean-field models of binary mixtures, and the failure\nof this analogy at the critical point due to shear rigidity. We then consider\nthe phase transition at fixed volume, a relatively unexplored paradigm for\npolymer gels that results in a phase-separated equilibrium consisting of\ncoexisting solvent-rich and solvent-poor regions of gel. Again, the gel's shear\nrigidity is found to have a profound effect on the phase transition, here\nresulting in macroscopic shape change at constant volume of the sample,\nexemplified by the tunable buckling of toroidal samples of polymer gel. By\ndrawing analogies with extreme mechanics, where large shape changes are\nachieved via mechanical instabilities, we formulate the notion of extreme\nthermodynamics, where large shape changes are achieved via thermodynamic\ninstabilities, i.e. phase transitions.",
        "positive": "Self Assembly of Janus Ellipsoids: We propose a primitive model of Janus ellipsoids that represent particles\nwith an ellipsoidal core and two semi-surfaces coded with dissimilar\nproperties, for example, hydrophobicity and hydrophilicity, respectively. We\ninvestigate the effects of the aspect ratio on the self-assembly morphology and\ndynamical aggregation processes using Monte Carlo simulations. We also discuss\ncertain differences between our results and those of earlier results for Janus\nspheres. In particular, we find that the size and structure of the aggregate\ncan be controlled by the aspect ratio."
    },
    {
        "anchor": "A universal scaling law for the evolution of granular gases: Dry, freely evolving granular materials in a dilute gaseous state coalesce\ninto dense clusters only due to dissipative interactions. This clustering\ntransition is important for a number of problems ranging from geophysics to\ncosmology. Here we show that the evolution of a dilute, freely cooling granular\ngas is determined in a universal way by the ratio of inertial flow and thermal\nvelocities, that is, the Mach number. Theoretical calculations and direct\nnumerical simulations of the granular Navier--Stokes equations show that\nirrespective of the coefficient of restitution, density or initial velocity\ndistribution, the density fluctuations follow a universal quadratic dependence\non the system's Mach number. We find that the clustering exhibits a scale-free\ndynamics but the clustered state becomes observable when the Mach number is\napproximately of $\\mathcal{O}(1)$. Our results provide a method to determine\nthe age of a granular gas and predict the macroscopic appearance of clusters.",
        "positive": "Local Reorientation Dynamics of Semiflexible Polymers in the Melt: The reorientation dynamics of local tangent vectors of chains in isotropic\namorphous melts containing semiflexible model polymers was studied by molecular\ndynamics simulations. The reorientation is strongly influenced both by the\nlocal chain stiffness and by the overall chain length. It takes place by two\ndifferent subsequent processes: A short-time non-exponential decay and a\nlong-time exponential reorientation arising from the relaxation of medium-size\nchain segments. Both processes depend on stiffness and chain length. The strong\ninfluence of the chain length on the chain dynamics is in marked contrast to\nits negligible effect on the static structure of the melt. The local structure\nshows only a small dependence on the stiffness, and is independent of chain\nlength. Calculated correlation functions related to double-quantum NMR\nexperiments are in qualitative agreement with experiments on entangled melts. A\nplateau is observed in the dependence of segment reorientation on the\nmean-squared displacement of the corresponding chain segments. This plateau\nconfirms, on one hand, the existence of reptation dynamics. On the other hand,\nit shows how the reptation picture has to be adapted if, instead of fully\nflexible chains, semirigid chains are considered."
    },
    {
        "anchor": "Dynamical density functional theory with hydrodynamic interaction: This paper has been withdrawn by the author due to the incorrect application\nof the divergence theorem to Eqs 7, 8 and 9.",
        "positive": "How interface geometry dictates water's thermodynamic signature in\n  hydrophobic association: As a common view the hydrophobic association between molecular-scale binding\npartners is supposed to be dominantly driven by entropy. Recent calorimetric\nexperiments and computer simulations heavily challenge this established\nparadigm by reporting that water's thermodynamic signature in the binding of\nsmall hydrophobic ligands to similar-sized apolar pockets is enthalpy-driven.\nHere we show with purely geometric considerations that this controversy can be\nresolved if the antagonistic effects of concave and convex bending on water\ninterface thermodynamics are properly taken into account. A key prediction of\nthis continuum view is that for fully complementary binding of the convex\nligand to the concave counterpart, water shows a thermodynamic signature very\nsimilar to planar (large-scale) hydrophobic association, that is,\nenthalpy-dominated, and hardly depends on the particular pocket/ligand\ngeometry. A detailed comparison to recent simulation data qualitatively\nsupports the validity of our perspective down to subnanometer scales. Our\nfindings have important implications for the interpretation of thermodynamic\nsignatures found in molecular recognition and association processes.\nFurthermore, traditional implicit solvent models may benefit from our view with\nrespect to their ability to predict binding free energies and entropies."
    },
    {
        "anchor": "Heat capacity of liquids in light of hydrodynamics as U(1) gauge theory: We investigate the heat capacity of liquids through a theoretical approach\nbased on a quasiparticle description. By interpreting the microscopic dynamics\nof particles in liquids in terms of quasiparticles, we suggest a simplified\nunderstanding of the number of degrees of freedom in liquids. A equivalence\nbetween hydrodynamics and U(1) gauge theory, which is newly proposed in the\npresent paper, develops the quasiparticle description to construct a new\nLagrangian which correctly reproduces the number of modes at the melting points\nand at the critical points. The heat capacity evaluated from this Lagrangian\nnaturally interpolates between these two points, and agrees with the phonon\ntheory of liquids [Sci. Rep. 2, 421 (2012)].",
        "positive": "Light-driven liquid crystalline nonlinear oscillator under optical\n  periodic forcing: An all-optically driven strategy to govern a liquid crystalline collective\nmolecular nonlinear oscillator is discussed. It does not require external\nfeedbacks of any kind while the oscillator and a time-depending perturbation\nboth are sustained by incident light. Various dynamical regimes such as\nfrequency -locked, quasiperiodic, forced and chaotic are observed in agreement\nwith a theoretical approach developed in the limit of the plane wave\napproximation."
    },
    {
        "anchor": "Hamilton's equations for a fluid membrane: Consider a homogenous fluid membrane described by the Helfrich-Canham energy,\nquadratic in the mean curvature of the membrane surface. The shape equation\nthat determines equilibrium configurations is fourth order in derivatives and\ncubic in the mean curvature. We introduce a Hamiltonian formulation of this\nequation which dismantles it into a set of coupled first order equations. This\ninvolves interpreting the Helfrich-Canham energy as an action; equilibrium\nsurfaces are generated by the evolution of space curves. Two features\ncomplicate the implementation of a Hamiltonian framework: (i) The action\ninvolves second derivatives. This requires treating the velocity as a phase\nspace variable and the introduction of its conjugate momentum. The canonical\nHamiltonian is constructed on this phase space. (ii) The action possesses a\nlocal symmetry -- reparametrization invariance. The two labels we use to\nparametrize points on the surface are themselves physically irrelevant. This\nsymmetry implies primary constraints, one for each label, that need to be\nimplemented within the Hamiltonian. The two lagrange multipliers associated\nwith these constraints are identified as the components of the acceleration\ntangential to the surface. The conservation of the primary constraints imply\ntwo secondary constraints, fixing the tangential components of the momentum\nconjugate to the position. Hamilton's equations are derived and the appropriate\ninitial conditions on the phase space variables are identified. Finally, it is\nshown how the shape equation can be reconstructed from these equations.",
        "positive": "Linking dynamics and structure in highly asymmetric ionic liquids: We explore an idealized theoretical model for the transport of ions within\nhighly asymmetric ionic liquid mixtures. A primitive model (PM)-inspired system\nserves as a representative for asymmetric ionic materials (such as liquid\ncrystalline salts) which quench to form disordered, partially-arrested phases.\nSelf-Consistent Generalized Langevin Equation (SCGLE) Theory is applied to\nunderstand the connection between the size ratio of charge-matched salts and\ntheir average mobility. Within this model, we identify novel glassy states\nwhere one of the two charged species (either the macro-cation or the\nmicro-anion) are arrested, while the other retains mobility. We discuss how\nthis result is useful in the development of novel single-ion conducting phases\nin ionic liquid based materials."
    },
    {
        "anchor": "Dynamical coupling between connected foam films by interface transfer\n  across the menisci: The highly confined flow of the liquid phase, trapped between the gas\nbubbles, is at the origin of the large effective viscosity of the liquid foams.\nDespite the industrial relevance of this complex fluid, the foam viscosity\nremains difficult to predict, because of the lack of flow characterization at\nthe bubble scale. Using an original deformable frame, we provide the first\nexperimental evidence of the interface transfer between a compressed film\n(resp. a stretched film) and its first neighbour, across their common meniscus.\nWe measure this transfer velocity, which is a key boundary condition for local\nflows in foams. We also show the dramatic film thickness variation induced by\nthis interface transfer, which may play an important role in the film thickness\ndistribution of a 3D foam sample.",
        "positive": "Active Diffusion of Self-Propelled Particles in Semi-Flexible Polymer\n  Networks: Mesh-like structures, such as mucus gel or cytoskeleton networks, are\nubiquitous in biological systems. These intricate structures are composed of\ncross-linked, semi-flexible bio-filaments, crucial to numerous biological\nprocesses. In many biological systems, active self-propelled particles like\nmotor proteins or bacteria navigate these intricate polymer networks. In this\nstudy, we develop a computational model of three-dimensional cubic-topological,\nswollen polymer networks of semi-flexible filaments. We perform Langevin\ndynamics simulations to investigate the diffusion of active tracer particles\nnavigating through these networks. By analyzing various physical observables,\nwe investigate the effects of mesh-to-particle size ratio, P\\'eclet number of\nactive particles, and bending stiffness of the polymer networks upon active\ntrapped-and-hopping diffusion of the tracer. When the tracer size is equal to\nor larger than the mesh size, the polymer stiffness substantially enhances\ntrapping while suppressing the hopping process. Notably, the mean trapped time\nexhibits an exponential growth law to the bending stiffness with an\nactivity-dependent slope. An analytic theory based on the mean first-passage\ntime of active particles in a harmonic potential is developed. Our findings\ndeepen the comprehension of the intricate interplay between the polymer's\nbending stiffness, tracer size, and the activity of tracer particles. This\nknowledge can shed light on important biological processes, such as\nmotor-driven cargo transport or drug delivery, which hinge on the behavior of\nactive particles within biological gels."
    },
    {
        "anchor": "Absorbing phase transitions in systems with mediated interactions: Experiments of periodically sheared colloidal suspensions or soft amorphous\nsolids display a transition from reversible to irreversible particle motion\nthat, when analysed stroboscopically in time, is interpreted as an absorbing\nphase transition with infinitely many absorbing states. In these systems\ninteractions mediated by hydrodynamics or elasticity are present, causing\npassive regions to be affected by nearby active ones. We show that mediated\ninteractions induce a new universality class of absorbing phase transitions,\ndistinct from Conserved Directed Percolation, and we obtain the corresponding\ncritical exponents. We do so with large-scale numerical simulations of a\nminimal model for the stroboscopic dynamics of sheared soft materials and\nderive the minimal field theoretical description.",
        "positive": "Investigating the role of boundary bricks in DNA brick self-assembly: In the standard DNA brick set-up, distinct 32-nucleotide strands of\nsingle-stranded DNA are each designed to bind specifically to four other such\nmolecules. Experimentally, it has been demonstrated that the overall yield is\nincreased if certain bricks which occur on the outer faces of target structures\nare merged with adjacent bricks. However, it is not well understood by what\nmechanism such `boundary bricks' increase the yield, as they likely influence\nboth the nucleation process and the final stability of the target structure.\nHere, we use Monte Carlo simulations with a patchy particle model of DNA bricks\nto investigate the role of boundary bricks in the self-assembly of complex\nmulticomponent target structures. We demonstrate that boundary bricks lower the\nfree-energy barrier to nucleation and that boundary bricks on edges stabilize\nthe final structure. However, boundary bricks are also more prone to\naggregation, as they can stabilize partially assembled intermediates. We\nexplore some design strategies that permit us to benefit from the stabilizing\nrole of boundary bricks whilst minimizing their ability to hinder assembly; in\nparticular, we show that maximizing the total number of boundary bricks is not\nan optimal strategy."
    },
    {
        "anchor": "Thermal Fluctuations of Anisotropic Semiflexible Polymers: Thermal fluctuations of microtubules (MTs) and other cytoskeletal filaments\ngovern to a great extent the complex rheological properties of the cytoskeleton\nin eukaryotic cells. In recent years, much effort has been put into capturing\nthe dynamics of these fluctuations by means of analytical and numerical models.\nThese attempts have been very successful for, but also remain limited to,\nisotropic polymers. To correctly interpret experimental work on (strongly)\nanisotropic semiflexible polymers, there is a need for a numerical modelling\ntool that accurately captures the dynamics of polymers with anisotropic\nmaterial properties. In the current study, we present a finite element (FE)\nframework for simulating the thermal dynamics of a single anisotropic\nsemiflexible polymer. First, we demonstrate the accuracy of our framework by\ncomparison of the simulated mean square displacement (MSD) of the end-to-end\ndistance with analytical predictions based on the worm-like chain model. Then,\nwe implement a transversely isotropic material model, characteristic for\nbiopolymers such as MTs, and study the persistence length for various ratios\nbetween the longitudinal shear modulus and corresponding Young's modulus.\nFinally, we put our findings in context by addressing a recent experimental\nwork on grafted transversely isotropic MTs. In that research, a simplified\nstatic mechanical model was used to deduce a very high level of MT anisotropy\nto explain the observation that the persistence length of grafted MTs increases\nas contour length increases. We show, by means of our FE framework, that the\nanisotropic properties cannot account for the reported length-dependent\npersistence length.",
        "positive": "Electrothermal active control of preconcentrated biomolecule plugs: Concentration polarization (CP) based biomolecule preconcentration is highly\neffective in enhancing the detection sensitivity, yet fails to precisely and\ndynamically control the location of the preconcentrated biomolecule plug to\nensure overlap with the sensing region (e.g. immobilized molecular probes).\nHere, we used electrothermal (ET) stirring as a means of controlling the\nlocation of a preconcentrated biomolecule plug. The applied microfluidic device\nconsisted of a Nafion membrane to induce the CP, and an array of individually\naddressable microscale heaters for active local ET stirring. The experimental\nresults demonstrated that such a novel platform enabled active control of the\nlocation of the preconcentrated plug of target biomolecules, ensuring its\noverlap with the functionalized microparticles, ultimately yielding enhanced\ndetection sensitivity and binding kinetics. This was demonstrated using\navidin-biotin particles as a simple bead-based bioassay model."
    },
    {
        "anchor": "Scale-Free Crystallization of two-dimensional Complex Plasmas: Domain\n  Analysis using Minkowski Tensors: Experiments of the recrystallization processes in two-dimensional complex\nplasmas are analyzed in order to rigorously test a recently developed\nscale-free phase transition theory. The \"Fractal-Domain-Structure\" (FDS) theory\nis based on the kinetic theory of Frenkel. It assumes the formation of\nhomogeneous domains, separated by defect lines, during crystallization and a\nfractal relationship between domain area and boundary length. For the defect\nnumber fraction and system energy a scale free power-law relation is predicted.\nThe long range scaling behavior of the bond order correlation function shows\nclearly that the complex plasma phase transitions are not of KTHNY type.\nPrevious preliminary results obtained by counting the number of dislocations\nand applying a bond order metric for structural analysis are reproduced. These\nfindings are supplemented by extending the use of the bond order metric to\nmeasure the defect number fraction and furthermore applying state-of-the-art\nanalysis methods, allowing a systematic testing of the FDS theory with\nunprecedented scrutiny: A morphological analysis of lattice structure is\nperformed via Minkowski tensor methods. Minkowski tensors form a complete\nfamily of additive, motion covariant and continuous morphological measures that\nare sensitive to non-linear properties. The FDS theory is rigorously confirmed\nand predictions of the theory are reproduced extremely well. The predicted\nscale-free power law relation between defect fraction number and system energy\nis verified for one more order of magnitude at high energies compared to the\ninherently discontinuous bond order metric. Minkowski Tensor analysis turns out\nto be a powerful tool for investigations of crystallization processes. It is\ncapable to reveal non-linear local topological properties, however, still\nprovides easily interpretable results founded on a solid mathematical\nframework.",
        "positive": "Geometrical dynamics of edge-driven surface growth: Accretion of mineralized thin wall-like structures via localized growth along\ntheir edges is observed in a range of physical and biological systems ranging\nfrom molluscan and brachiopod shells to carbonate-silica composite\nprecipitates. To understand the shape of these mineralized structures, we\ndevelop a mathematical framework that treats the thin-walled shells as a smooth\nsurface left in the wake of the growth front that can be described as an\nevolving space curve. Our theory then takes an explicit geometric form for the\nprescription of the velocity of the growth front curve, along with some\ncompatibility relations and a closure equation related to the nature of surface\ncurling. The result is a set of equations for the geometrical dynamics of a\ncurve that leaves behind a compatible surface. Solutions of these equations\ncapture a range of geometric precipitate patterns seen in abiotic and biotic\nforms across scales. In addition to providing a framework for the growth and\nform of these thin-walled morphologies, our theory suggests a new class of\ndynamical systems involving moving space curves that are compatible with\nnon-Euclidean embeddings of surfaces."
    },
    {
        "anchor": "Many-Body Electrostatic Forces Between Colloidal Particles at Vanishing\n  Ionic Strength: Electrostatic forces between small groups of colloidal particles are measured\nusing blinking optical tweezers. When the electrostatic screening length is\nsignificantly larger than the particle radius, forces are found to be\nnon-pairwise additive. Both pair and multi-particle forces are well described\nby the linearized Poisson-Boltzmann equation with constant potential boundary\nconditions. These findings may play an important role in understanding the\nstructure and stability of a wide variety of systems, from micron-sized\nparticles in oil to aqueous nanocolloids.",
        "positive": "Orientation and microstructure in sheared Brownian suspensions of\n  anisotropic dicolloidal particles: Orientation and microstructure are investigated in sheared Brownian\nsuspensions of hard dicolloidal particles, with the dicolloids modeled as two\nfused spheres of varying radii and center to center separations. Two different\nparticle shapes named homonuclear (aspect ratio 1.1) and fused-dumbbells\n(aspect ratio 1.5) were considered. Hydrodynamic interactions between the\nparticles were computed with a modified lubrication model called Fast\nLubrication Dynamics. Studies were conducted for a wide range of volume\nfractions between $0.3 \\leq \\phi \\leq 0.5$ and P\\`{e}clet numbers between $0\n\\leq Pe \\leq 1000$. The microstructure was found to be disordered at all volume\nfractions, though signatures of weak string like ordering were evident\nparticularly in $\\phi=0.5$ homonuclear suspensions at intermediate to high\nshear rates ($Pe$ in the range 10-100). Complex orientation behavior was\nobserved as a function of shape, shear rates, and volume fractions. At very low\nshear rates, random orientation distribution was observed in all cases. At the\nhighest shear rates, orientation distribution in suspensions of homonuclear\nparticles exhibited a shift towards an alignment with the vorticity axis at all\nvolume fractions, while in suspensions of fused-dumbbells it exhibited a shift\naway from the vorticity axis at low volume fractions and a negligible shift at\nhigher volume fractions. The orientation behavior is further characterized by\nexamining the orientation distribution in the velocity--gradient plane -- in\nthis case an increased particle alignment with the velocity axis is generally\nobserved with increasing volume fractions, but not universally with increasing\nshear rates. Mechanistic origins for the complex orientation behavior as a\nfunction of shear rate, volume fraction, and particle shape is described."
    },
    {
        "anchor": "Statistical mechanics of semiflexible ribbon polymers: The statistical mechanics of a ribbon polymer made up of two semiflexible\nchains is studied using both analytical techniques and simulation. The system\nis found to have a crossover transition at some finite temperature, from a type\nof short range order to a fundamentally different sort of short range order. In\nthe high temperature regime, the 2-point correlation functions of the object\nare identical to worm-like chains, while in the low temperature regime they are\ndifferent due to a twist structure. The crossover happens when the persistence\nlength of individual strands becomes comparable to the thickness of the ribbon.\nIn the low temperature regime, the ribbon is observed to have a novel\n``kink-rod'' structure with a mutual exclusion of twist and bend in contrast to\nsmooth worm-like chain behaviour. This is due to its anisotropic rigidity and\ncorresponds to an {\\it infinitely} strong twist-bend coupling. The\ndouble-stranded polymer is also studied in a confined geometry. It is shown\nthat when the polymer is restricted in a particular direction to a size less\nthan the bare persistence length of the individual strands, it develops zigzag\nconformations which are indicated by an oscillatory tangent-tangent correlation\nfunction in the direction of confinement. Increasing the separation of the\nconfining plates leads to a crossover to the free behaviour, which takes place\nat separations close to the bare persistence length. These results are expected\nto be relevant for experiments which involve complexation of two or more stiff\nor semiflexible polymers.",
        "positive": "Crystalline shielding mitigates structural rearrangement and localizes\n  memory in jammed systems under oscillatory shear: The nature of yield in amorphous materials under stress has yet to be fully\nelucidated. In particular, understanding how microscopic rearrangement gives\nrise to macroscopic structural and rheological signatures in disordered systems\nis vital for the prediction and characterization of yield and for the study of\nhow memory is stored in disordered materials. Here, we investigate the\nevolution of local structural homogeneity on an individual particle level in\namorphous jammed two-dimensional systems under oscillatory shear, and relate\nthis evolution to rearrangement, memory, and macroscale rheological\nmeasurements. We identify a new structural metric, crystalline shielding, that\nis predictive of rearrangement propensity and the structural volatility of\nindividual particles under shear. We use this metric to identify localized\nregions of the system in which the material's memory of its preparation is\npreserved. Our results contribute to a growing understanding of how local\nstructure relates to dynamic response and memory in disordered systems."
    },
    {
        "anchor": "Adiabaticity in Nonlinear Quantum Dynamics: Bose-Einstein Condensate in\n  a Temporally-Varying Box: A simple model of an atomic Bose-Einstein condensate in a box whose size\nvaries with time is studied to determine the nature of adiabaticity in the\nnonlinear dynamics obtained within the Gross-Pitaevskii equation (the nonlinear\nSchr\\\"{o}dinger equation). Analytical and numerical methods are used to\ndetermine the nature of adiabaticity in this nonlinear quantum system. Criteria\nfor validity of an adiabatic approximation are formulated.",
        "positive": "Thermodynamics and kinetics of crystallisation in deeply supercooled\n  Stillinger-Weber silicon: We study the kinetics of crystallization in deeply supercooled liquid silicon\nemploying computer simulations and the Stillinger-Weber three body potential.\nThe free energy barriers to crystallisation are computed using umbrella\nsampling Monte Carlo simulations, and for selected low temperature and zero\npressure state points, using unconstrained molecular dynamics simulations to\nreconstruct the free energy from a mean first passage time formulation. We\nfocus on state points that have been described in earlier work [Sastry and\nAngell, Nature Mater., 2, 739, 2003] as straddling a first order liquid-liquid\nphase transition (LLPT) between two metastable liquid states. It was argued\nsubsequently [Ricci et al., Mol. Phys., 117, 3254, 2019] that the apparent\nphase transition is in fact due the loss of metastability of the liquid state\nwith respect to the globally stable crystalline state. The presence or absence\nof a barrier to crystallization for these state points is therefore of\nimportance to ascertain, with due attention to ambiguities that may arise from\nthe choice of order parameters. We discuss our choice of order parameters and\nalso our choice of methods to calculate the free energy at deep supercooling.\nWe find a well-defined free energy barrier to crystallisation and demonstrate\nthat both umbrella sampling and mean first passage time methods yield results\nthat agree quantitatively. Our results thus provide strong evidence against the\npossibility that the liquids at state points close to the reported LLPT exhibit\nslow, spontaneous crystallisation, but they do not address the existence of a\nLLPT (or lack thereof). We also compute the free energy barriers to\ncrystallisation at other state points over a broad range of temperatures and\npressures, and discuss the effect of changes in the microscopic structure of\nthe metastable liquid on the free energy barrier heights."
    },
    {
        "anchor": "Lifshitz points in blends of AB and BC diblock copolymers: We consider micro- and macro- phase separation in blends of AB and BC diblock\ncopolymers. We show that, depending on architecture, a number of phase diagram\ntopologies are possible. Microphase separation or macrophase separation can\noccur, and there are a variety of possible Lifshitz points. Because of the rich\nparameter space, Lifshitz points of multiple order are possible. We demonstrate\nLifshitz points of first and second order, and argue that, in principle, up to\n5th order Lifshitz points are possible.",
        "positive": "Mesoscale modeling of the rheology of pressure sensitive adhesives\n  through inclusion of transient forces: For optimal application, pressure-sensitive adhesives must have rheological\nproperties in between those of a viscoplastic solid and those of a viscoelastic\nliquid. Such adhesives can be produced by emulsion polymerisation, resulting in\nlatex particles which are dispersed in water and contain long-chain acrylic\npolymers. When the emulsion is dried, the latex particles coalesce and an\nadhesive film is formed. The rheological properties of the dried samples are\nbelieved to be dominated by the interface regions between the original latex\nparticles, but the relation between rheology and latex particle properties is\npoorly understood. In this paper we show that it is possible to describe the\nbulk rheology of a pressure-sensitive adhesive by means of a mesoscale\nsimulation model. To reach experimental time and length scales, each latex\nparticle is represented by just one simulated particle. The model is subjected\nto oscillatory shear flow and extensional flow. Simple order of magnitude\nestimates of the model parameters already lead to semi-quantitative agreement\nwith experimental results. We show that inclusion of transient forces in the\nmodel, i.e. forces with memory of previous configurations, is essential to\ncorrectly predict the linear and nonlinear properties."
    },
    {
        "anchor": "Nucleated dewetting in supported ultra-thin liquid films with\n  hydrodynamic slip: This study reveals the influence of the surface energy and solid/liquid\nboundary condition on the breakup mechanism of dewetting ultra-thin polymer\nfilms. Using silane self-assembled monolayers, SiO$_2$ substrates are rendered\nhydrophobic and provide a strong slip rather than a no-slip solid/liquid\nboundary condition. On undergoing these changes, the thin-film breakup\nmorphology changes dramatically -- from a spinodal mechanism to a breakup which\nis governed by nucleation and growth. The experiments reveal a dependence of\nthe hole density on film thickness and temperature. The combination of lowered\nsurface energy and hydrodynamic slip brings the studied system closer to the\nconditions encountered in bursting unsupported films. As for unsupported\npolymer films, a critical nucleus size is inferred from a free energy model.\nThis critical nucleus size is supported by the film breakup observed in the\nexperiments using high speed \\emph{in situ} atomic force microscopy.",
        "positive": "Non-additive symmetric mixtures at selective walls: The results of Monte Carlo simulation of adsorption and wetting behaviour of\na highly non-additive symmetric mixture at selective walls is discussed. We\nhave concentrated on the interplay between the surface induced demixing in the\nadsorbed films and the properties of the bulk mixture, which exhibits a closed\nimmiscibility loop. It has been shown that the wetting behaviour depends on the\nabsolute values of the parameters determining the strengths of interaction\nbetween the mixture components and the surface, as well as on their difference.\nIn general, an increase of the difference between the adsorption energies of\nthe components leads to a decrease of the wetting temperature. In the cases\nwhen the wetting of non-selective walls occurs at the temperatures above the\nonset of demixing transition in the bulk, an increasing wall selectivity leads\nto a gradual decrease of the wetting temperature towards the triple point, in\nwhich the vapour coexists with the mixed and demixed liquid phases. When the\nwetting temperature at the non-selective wall is located below the onset of the\ndemixing transition in the bulk mixture, an increase of the adsorption energy\nof the selected component causes the developing adsorbed films to demix and to\nshow the reentrant mixing upon approaching the bulk coexistence. At the\ntemperatures above the onset of the demixing transition in the bulk, the\nadsorbed films remain demixed up to the bulk coexistence and undergo the\nfirst-order wetting transition. A rather unexpected finding has been the\nobservation of a gradual increase of the wetting temperature at highly\nselective walls."
    },
    {
        "anchor": "Fractional size dependence of surface tension of a growing nucleus with\n  an inhomogeneous interface: The surface energy of the nucleus of a stable phase growing in the presence\nof several amorphous metastable phases of character intermediate between the\ninitial and the final phases may depend non-trivially on the size of the\nnucleus. This size dependence is being increasingly used to explain diverse\nnon-equilibrium phase selection, and relaxation, as in the random first-order\ntransition (RFOT) theory of glasses. Here we develop an order parameter based\nGinzburg-Landau approach that explicitly includes the rugged free energy\nlandscape due to the metastable phases. The fractional dependence of total\nsurface energy between melt and stable solid phase on the number of metastable\nphases($N_{MS}$) has been interrogated in this study. We have also analyzed how\nthis fractional dependence gets modified with temperature. We find that the\nfractional size dependence of surface energy is omnipresent, arises from the\nminimization of free energy and demands certain ordering of metastable phases\nin the interface. Our results could recover the celebrated result of Villain\nthat forms the basis of RFOT theory of glasses. We find the additional result\nthat the surface tension saturates to a finite size independent value.",
        "positive": "Multiple glass transitions and higher order replica symmetry breaking of\n  binary mixtures: We extend the replica liquid theory in order to describe the multiple glass\ntransitions of binary mixtures with large size disparities, by taking into\naccount the two-step replica symmetry breaking (2RSB). We determine the glass\nphase diagram of the mixture of large and small particles in the\nlarge-dimension limit where the mean-field theory becomes exact. When the size\nratio of particles is beyond a critical value, the theory predicts three\ndistinct glass phases; (i) the 1RSB double glass where both components vitrify\nsimultaneously, (ii) the 1RSB single glass where only large particles are\nfrozen while small particles remain mobile, and (iii) a new glass phase called\nthe 2RSB double glass where both components vitrify simultaneously but with an\nenergy landscape topography distinct from the 1RSB double glass."
    },
    {
        "anchor": "Explicit kinematic equations for degree-4 rigid origami vertices,\n  Euclidean and non-Euclidean: We derive new algebraic equations for the folding angle relationships in\ncompletely general degree-four rigid-foldable origami vertices, including both\nEuclidean (developable) and non-Euclidean cases. These equations in turn lead\nto novel, elegant equations for the general developable degree-four case. We\ncompare our equations to previous results in the literature and provide two\nexamples of how the equations can be used: In analyzing a family of square\ntwist pouches with discrete configuration spaces, and for proving that a new\nfolding table design made with hyperbolic vertices has a single folding mode.",
        "positive": "Short time dynamics determine glass forming ability in a glass\n  transition two-level model: a stochastic approach using Kramers' escape\n  formula: The relationship between short and long time relaxation dynamics is obtained\nfor a simple solvable two-level energy landscape model of a glass. This is done\nthrough means of the Kramers transition theory, which arises in very natural\nmanner to calculate transition rates between wells. Then the corresponding\nstochastic master equation is analytically solved to find the population of\nmetastable states. A relation between the cooling rate, the characteristic\nrelaxation time and the population of metastable states is found from the\nsolution of such equation. From this, a relationship between the relaxation\ntimes and the frequency of oscillation at the metastable states, i.e., the\nshort time dynamics is obtained. Since the model is able to capture either a\nglass transition or a crystallization depending on the cooling rate, this gives\na conceptual framework in which to discuss some aspects of rigidity theory."
    },
    {
        "anchor": "Dynamics of Phase Behavior of a Polymer Blend Under Shear Flow: We study the dynamics of the phase behavior of a polymer blend in the\npresence of shear flow. By adopting a two fluid picture and using a\ngeneralization of the concept of material derivative, we construct kinetic\nequations that describe the phase behavior of polymer blends in the presence of\nexternal flow. A phenomenological form for the shear modulus for the blend is\nproposed. The study indicates that a nonlinear dependence of the shear modulus\nof the blend on the volume fraction of one of the species is crucial for a\nshift in the stability line to be induced by shear flow.",
        "positive": "The modified Langevin description for probes in a nonlinear medium: When the motion of a probe strongly disturbs the thermal equilibrium of the\nsolvent or bath, the nonlinear response of the latter must enter the probe's\neffective evolution equation. We derive that induced stochastic dynamics using\nsecond order response around the bath thermal equilibrium. We discuss the\nnature of the new term in the evolution equation which is not longer purely\ndissipative, and the appearance of a novel time-scale for the probe related to\nchanges in the dynamical activity of the bath. A major application for the\nobtained nonlinear generalized Langevin equation is in the study of colloid\nmotion in a visco-elastic medium."
    },
    {
        "anchor": "Floppy swimming: Viscous locomotion of actuated elastica: Actuating periodically an elastic filament in a viscous liquid generally\nbreaks the constraints of Purcell's scallop theorem, resulting in the\ngeneration of a net propulsive force. This observation suggests a method to\ndesign simple swimming devices - which we call \"elastic swimmers\" - where the\nactuation mechanism is embedded in a solid body and the resulting swimmer is\nfree to move. In this paper, we study theoretically the kinematics of elastic\nswimming. After discussing the basic physical picture of the phenomenon and the\nexpected scaling relationships, we derive analytically the elastic swimming\nvelocities in the limit of small actuation amplitude. The emphasis is on the\ncoupling between the two unknowns of the problems - namely the shape of the\nelastic filament and the swimming kinematics - which have to be solved\nsimultaneously. We then compute the performance of the resulting swimming\ndevice, and its dependance on geometry. The optimal actuation frequency and\nbody shapes are derived and a discussion of filament shapes and internal\ntorques is presented. Swimming using multiple elastic filaments is discussed,\nand simple strategies are presented which result in straight swimming\ntrajectories. Finally, we compare the performance of elastic swimming with that\nof swimming microorganisms.",
        "positive": "Indentation of a Rigid Sphere into an Elastic Substrate with Surface\n  Tension and Adhesion: The surface tension of compliant materials such as gels provides resistance\nto deformation in addition to and sometimes surpassing that due to elasticity.\nThis article studies how surface tension changes the contact mechanics of a\nsmall hard sphere indenting a soft elastic substrate. Previous studies have\nexamined the special case where the external load is zero, so contact is driven\nby adhesion alone. Here, we tackle the much more complicated problem where, in\naddition to adhesion, deformation is driven by an indentation force. We present\nan exact solution based on small strain theory. The relation between\nindentation force (displacement) and contact radius is found to depend on a\nsingle dimensionless parameter: $\\omega=\\sigma(\\mu R)^{-2/3}(9\\pi\nW_{\\textrm{ad}}/4)^{-1/3}$, where $\\sigma$ and $\\mu$ are the surface tension\nand shear modulus of the substrate, $R$ is the sphere radius, and\n$W_{\\textrm{ad}}$ is the interfacial work of adhesion. Our theory reduces to\nthe Johnson-Kendall-Roberts theory and Young-Dupr\\'e equation in the limits of\nsmall and large $\\omega$ respectively, and compares well with existing\nexperimental data. Our results show that, although surface tension can\nsignificantly affect the indentation force, the magnitude of the pull-off load\nin the partial wetting liquid-like limit is reduced only by 1/3 compared with\nthe JKR limit, and the pull-off behavior is completely determined by $\\omega$."
    },
    {
        "anchor": "Arrhenius temperature dependence of the crystallization time of deeply\n  supercooled liquids: Usually, supercooled liquids and glasses are thermodynamically unstable\nagainst crystallization. Classical nucleation theory (CNT) has been used to\ndescribe the crystallization dynamics of supercooled liquids. However, recent\nstudies on overcompressed hard spheres show that their crystallization dynamics\nare intermittent and mediated by avalanche-like rearrangements of particles,\nwhich largely differ from the CNT. These observations suggest that the\ncrystallization times of deeply supercooled liquids or glasses cannot be\ndescribed by the CNT, but this point has not yet been studied in detail. In\nthis paper, we use molecular dynamics simulations to study the crystallization\ndynamics of soft spheres just after an instantaneous quench. We show that\nalthough the equilibrium relaxation time increases in a super-Arrhenius manner\nwith decreasing temperature, the crystallization time shows an Arrhenius\ntemperature dependence at very low temperatures. This is contrary to the\nconventional formula based on the CNT. Furthermore, the estimated energy\nbarrier for the crystallization is surprisingly small compared to that for the\nequilibrium dynamics. By comparing the crystallization and aging dynamics\nquantitatively, we show that a coupling between aging and crystallization is\nthe key for understanding the rapid crystallization of deeply supercooled\nliquids or glasses.",
        "positive": "Bottlenecks in granular flow: When does an obstacle increase the\n  flowrate in an hourglass?: Bottlenecks occur in a wide range of applications from pedestrian and traffic\nflow to mineral and food processing. We examine granular flow across a\nbottleneck using particle-based simulations. Contrary to expectations we find\nthat the flowrate across a bottleneck actually increases if an opti- mized\nobstacle is placed before it. The dependency of flowrate on obstacle diameter\nis derived using a phenomenological velocity-density relationship that peaks at\na critical density. This relationship is in stark contrast to models of traffic\nflow, as the mean velocity does not depend only on density but attains\nhysteresis due to interaction of particles with the obstacle."
    },
    {
        "anchor": "Modeling semiflexible polymer networks: Here, we provide an overview of theoretical approaches to semiflexible\npolymers and their networks. Such semiflexible polymers have large bending\nrigidities that can compete with the entropic tendency of a chain to crumple up\ninto a random coil. Many studies on semiflexible polymers and their assemblies\nhave been motivated by their importance in biology. Indeed, crosslinked\nnetworks of semiflexible polymers form a major structural component of tissue\nand living cells. Reconstituted networks of such biopolymers have emerged as a\nnew class of biological soft matter systems with remarkable material\nproperties, which have spurred many of the theoretical developments discussed\nhere. Starting from the mechanics and dynamics of individual semiflexible\npolymers, we review the physics of semiflexible bundles, entangled solutions\nand disordered cross-linked networks. Finally, we discuss recent developments\non marginally stable fibrous networks, which exhibit critical behavior similar\nto other marginal systems such as jammed soft matter.",
        "positive": "High-resolution of particle contacts via fluorophore exclusion in\n  deep-imaging of jammed colloidal packings: Understanding the structural properties of random packings of jammed colloids\nrequires an unprecedented high-resolution determination of the contact network\nproviding mechanical stability to the packing. Here, we address the\ndetermination of the contact network by a novel strategy based on fluorophore\nsignal exclusion of quantum dot nanoparticles from the contact points. We use\nfluorescence labeling schemes on particles inspired by biology and biointerface\nscience in conjunction with fluorophore exclusion at the contact region. The\nmethod provides high-resolution contact network data that allows us to measure\nstructural properties of the colloidal packing near marginal stability. We\ndetermine scaling laws of force distributions, soft modes, correlation\nfunctions, coordination number and free volume that define the universality\nclass of jammed colloidal packings and can be compared with theoretical\npredictions. The contact detection method opens up further experimental testing\nat the interface of jamming and glass physics."
    },
    {
        "anchor": "Steady-state hydrodynamic instabilities of active liquid crystals:\n  Hybrid lattice Boltzmann simulations: We report hybrid lattice Boltzmann (HLB) simulations of the hydrodynamics of\nan active nematic liquid crystal sandwiched between confining walls with\nvarious anchoring conditions. We confirm the existence of a transition between\na passive phase and an active phase, in which there is spontaneous flow in the\nsteady state. This transition is attained for sufficiently ``extensile'' rods,\nin the case of flow-aligning liquid crystals, and for sufficiently\n``contractile'' ones for flow-tumbling materials. In a quasi-1D geometry, deep\nin the active phase of flow-aligning materials, our simulations give evidence\nof hysteresis and history-dependent steady states, as well as of spontaneous\nbanded flow. Flow-tumbling materials, in contrast, re-arrange themselves so\nthat only the two boundary layers flow in steady state. Two-dimensional\nsimulations, with periodic boundary conditions, show additional instabilities,\nwith the spontaneous flow appearing as patterns made up of ``convection\nrolls''. These results demonstrate a remarkable richness (including dependence\non anchoring conditions) in the steady-state phase behaviour of active\nmaterials, even in the absence of external forcing; they have no counterpart\nfor passive nematics. Our HLB methodology, which combines lattice Boltzmann for\nmomentum transport with a finite difference scheme for the order parameter\ndynamics, offers a robust and efficient method for probing the complex\nhydrodynamic behaviour of active nematics.",
        "positive": "Medium Amplitude Parallel Superposition (MAPS) Rheology, Part 2:\n  Experimental Protocols and Data Analysis: An experimental protocol is developed to directly measure the new material\nfunctions revealed by medium amplitude parallel superposition (MAPS) rheology.\nThis experimental protocol measures the medium amplitude response of a material\nto a simple shear deformation composed of three sine waves at different\nfrequencies. Imposing this deformation and measuring the mechanical response\nreveals a rich data set consisting of up to 19 measurements of the third order\ncomplex modulus at distinct three-frequency coordinates. We discuss how the\nchoice of the input frequencies influences the features of the MAPS domain\nstudied by the experiment. A polynomial interpolation method for reducing the\nbias of measured values from spectral leakage and variance due to noise is\ndiscussed, including a derivation of the optimal range of amplitudes for the\ninput signal. This leads to the conclusion that conducting the experiment in a\nstress-controlled fashion possesses a distinct advantage to the\nstrain-controlled mode. The experimental protocol is demonstrated through\nmeasurements of the MAPS response of a model complex fluid: a surfactant\nsolution of wormlike micelles. The resulting data set is indeed large and\nfeature-rich, while still being acquired in a time comparable to similar medium\namplitude oscillatory shear (MAOS) experiments. We demonstrate that the data\nrepresents measurements of an intrinsic material function by studying its\ninternal consistency, its compatibility with low-frequency predictions for\nColeman-Noll simple fluids, and its agreement with data obtained via MAOS\namplitude sweeps. Finally, the data is compared to predictions from the\ncorotational Maxwell model to demonstrate the power of MAPS rheology in\ndetermining whether a constitutive model is consistent with a material's\ntime-dependent response."
    },
    {
        "anchor": "Au-Ag template stripped pattern for scanning probe investigations of DNA\n  arrays produced by Dip Pen Nanolithography: We report on DNA arrays produced by Dip Pen Nanolithography (DPN) on a novel\nAu-Ag micro patterned template stripped surface. DNA arrays have been\ninvestigated by atomic force microscopy (AFM) and scanning tunnelling\nmicroscopy (STM) showing that the patterned template stripped substrate enables\neasy retrieval of the DPN-functionalized zone with a standard optical\nmicroscope permitting a multi-instrument and multi-technique local detection\nand analysis. Moreover the smooth surface of the Au squares (abput 5-10\nangstrom roughness) allows to be sensitive to the hybridization of the\noligonucleotide array with label-free target DNA. Our Au-Ag substrates,\ncombining the retrieving capabilities of the patterned surface with the\nsmoothness of the template stripped technique, are candidates for the\ninvestigation of DPN nanostructures and for the development of label free\ndetection methods for DNA nanoarrays based on the use of scanning probes.",
        "positive": "Interplay between viscosity and elasticity in freely expanding liquid\n  sheets: We investigate the dynamics of freely expanding liquid sheets prepared with\nfluids with different rheological properties, (i) viscous fluids with a\nzero-shear viscosity $\\eta_0$ in the range $(1-1000) \\, \\mathrm{mPa.s}$ and\n(ii) viscoelastic Maxwell fluids whose elastic modulus, $G_0$, characteristic\nrelaxation time, $\\tau$, and zero-shear viscosity, $\\eta_0=G_0 \\tau$, can be\ntuned over several orders of magnitude. The sheets are produced by impacting a\ndrop of fluid on a small cylindrical solid target. For viscoelastic fluids, we\nshow that, when $\\tau$ is shorter than the typical lifetime of the sheet ($\\sim\n10$ ms), the dynamics of the sheet is similar to that of Newtonian viscous\nliquids with equal zero-shear viscosity. In that case, for little viscous\nsamples ($\\eta_0 <\\sim 30$ mPa.s), the maximal expansion of the sheet,\n$d_{\\rm{max}}$, is independent of $\\eta_0$, whereas for more viscous samples,\n$d_{\\rm{max}}$ decreases as $\\eta_0$ increases. We provide a simple model to\naccount for the dependence of the maximal expansion of the sheet with the\nviscosity that is based on an energy balance between inertia, surface tension\nand viscous shear dissipation on the solid target, and which accounts well for\nour experimental data. By contrast, when $\\tau$ is longer than the typical\nlifetime of the sheet, the behavior drastically differs. The sheet expansion is\nstrongly enhanced as compared to that of viscous samples with comparable\nzero-shear viscosity, but is heterogeneous with the occurrence of cracks,\nrevealing the elastic nature of the viscoelastic fluid."
    },
    {
        "anchor": "Brownian Motion of Arbitrarily Shaped Particles in Two-Dimensions: Here we implement microfabricated boomerang particles with unequal arm\nlengths as a model for non-symmetry particles and study their Brownian motion\nin a quasi-two dimensional geometry by using high precision single particle\nmotion tracking. We show that due to the coupling between translation and\nrotation, the mean squared displacements of a single asymmetric boomerang\nparticle exhibit a non-linear crossover from short time faster to long time\nslower diffusion, and the mean displacements for fixed initial orientation are\nnon-zero and saturate out at long time. The measured anisotropic diffusion\ncoefficients versus the tracking point position indicate that there exists one\nunique point, i.e. the center of hydrodynamic stress (CoH), at which all\ncoupled diffusion coefficients vanish. This implies that in contrast to motion\nin 3D where the CoH only exists for high symmetry particles, the CoH always\nexists for Brownian motion in 2D. We develop an analytical model based on\nLangevin theory to explain the experimental results and show that among the 6\nanisotropic diffusion coefficients only 5 are independent because the\ntranslation-translation coupling originates from the translation-rotation\ncoupling. Finally we classify the behavior of 2D Brownian motion of arbitrarily\nshaped particles into four groups based on the particle shape symmetry group.",
        "positive": "Elementary vibrational model for transport properties of dense fluids: A vibrational model of transport properties of dense fluids assumes that\nsolid-like oscillations of atoms around their temporary equilibrium positions\ndominate the dynamical picture. The temporary equilibrium positions of atoms do\nnot form any regular structure and are not fixed, unlike in solids. Instead,\nthey are allowed to diffuse and this is why liquids can flow. However, this\ndiffusive motion is characterized by much longer time scales compared to those\nof solid-like oscillations. Although this general picture is not particularly\nnew, only in a recent series of works it has been possible to construct a\ncoherent and internally consistent {\\it quantitative} description of transport\nproperties such as self-diffusion, shear viscosity, and thermal conductivity.\nMoreover, the magnitudes of these transport coefficients have been related to\nthe properties of collective excitations in dense fluids. Importantly, the\nmodel is simple and no free parameters are involved. Recent achievements are\nsummarized in this overview. Application of the vibrational model to various\nsingle-component model systems such as plasma-related Coulomb and screened\nCoulomb (Yukawa) fluids, the Lennard-Jones fluid, and the hard-sphere fluid is\nconsidered in detail. Applications to real liquids are also briefly discussed.\nOverall, good to excellent agreement with available numerical and experimental\ndata is demonstrated. Conditions of applicability of the vibrational model and\na related question concerning the location of the gas-liquid crossover are\ndiscussed."
    },
    {
        "anchor": "Synergistic action in colloidal heat engines coupled by non-conservative\n  flows: Collective operation of multiple engines to achieve a common objective is a\nvital step in the design of complex machines. Recent studies have reduced the\nlength scales of engine design to micro and nanometers. While strategies to\nbuild complex machines from these remain to be devised, even the basic design\nprinciples remain obscure. Here, we construct and analyze the simplest\ncollection of two engines from a pair of colloidal microspheres in optical\ntraps at close separation. We demonstrate that at such proximity,\nnon-conservative scattering forces that were hitherto neglected, affect the\nparticle motion and hydrodynamics arising from dissipating these results in\nviolating zeroth law of thermodynamics. Leveraging this in a manner analogous\nto microswimmers and active Brownian particles, we show that a collection of\ntwo interacting engines outperform those that are well separated. While these\nresults explore the simplest case of two engines, the underlying concepts could\naid in designing larger collections akin to biological systems.",
        "positive": "Local orientational ordering in fluids of spherical molecules with\n  dipolar-like anisotropic adhesion: We discuss some interesting physical features stemming from our previous\nanalytical study of a simple model of a fluid with dipolar-like interactions of\nvery short range in addition to the usual isotropic Baxter potential for\nadhesive spheres. While the isotropic part is found to rule the global\nstructural and thermodynamical equilibrium properties of the fluid, the weaker\nanisotropic part gives rise to an interesting short-range local ordering of\nnearly spherical condensation clusters, containing short portions of chains\nhaving nose-to-tail parallel alignment which runs antiparallel to adjacent\nsimilar chains."
    },
    {
        "anchor": "The role of microscopic friction in statistics and scaling laws of\n  avalanches: We investigate statistics and scaling laws of avalanches in two-dimensional\nfrictional particles by numerical simulations. We find that the critical\nexponent for avalanche size distributions is governed by microscopic friction\nbetween the particles in contact, where the exponent is larger and closer to\nmean-field predictions if the friction coefficient is finite. We reveal that\nmicroscopic ``slips\" between frictional particles induce numerous small\navalanches which increase the slope, as well as the power-law exponent, of\navalanche size distributions. We also analyze statistics and scaling laws of\nthe avalanche duration and maximum stress drop rates, and examine power spectra\nof stress drop rates. Our numerical results suggest that the microscopic\nfriction is a key ingredient of mean-field descriptions and plays a crucial\nrole in avalanches observed in real materials.",
        "positive": "Tunability of the elastocaloric response in main-chain liquid\n  crystalline elastomers: Materials exhibiting a large caloric effect could lead to the development of\nnew generation of heat-management technologies that will have better energy\nefficiency and be potentially more environmentally friendly. The focus of\ncaloric materials investigations has shifted recently from solid-state\nmaterials toward soft materials, such as liquid crystals and liquid crystalline\nelastomers. It has been shown recently that a large electrocaloric effect\nexceeding 7 K can be observed in smectic liquid crystals. Here, we report on a\nsignificant elastocaloric response observed by direct elastocaloric\nmeasurements in main-chain liquid crystal elastomers. It is demonstrated that\nthe character of the nematic to paranematic/isotropic transition can be tuned\nfrom the supercritical regime towards the first-order regime, by decreasing the\ndensity of crosslinkers. In the latter case, the latent heat additionally\nenhances the elastocaloric response. Our results indicate that a significant\nelastocaloric response is present in main-chain liquid crystalline elastomers,\ndriven by stress fields much smaller than in solid elastocaloric materials.\nTherefore, elastocaloric soft materials can potentially play a significant role\nas active cooling/heating elements in the development of new heat-management\ndevices."
    },
    {
        "anchor": "The effective temperature for the thermal fluctuations in hot Brownian\n  motion: We revisit the effective parameter description of hot Brownian motion -- a\nscenario where a colloidal particle is kept at an elevated temperature than the\nambient fluid. Due to the time scale separation between heat diffusion and\nparticle motion, a stationary halo of hot fluid is carried along with the\nparticle, resulting in a spatially varying comoving temperature and viscosity\nprofile. The resultant Brownian motion in the overdamped limit can be well\ndescribed by a Langevin equation with effective parameters such as effective\ntemperature $T_{\\rm HBM}$ and friction coefficient $\\zeta_{\\rm HBM}$ that\nquantifies the thermal fluctuations and the diffusivity of the particle. These\nparameters can exactly be calculated using the framework of fluctuating\nhydrodynamics. Additionally, it was also observed that configurational and the\nkinetic degrees of freedom admits to different effective temperatures,\n$T^{\\mathbf{x}}_{\\rm HBM}$ and $T^{\\mathbf{v}}_{\\rm HBM}$, respectively, with\nthe former predicted accurately from fluctuating hydrodynamics. A more rigorous\ncalculation by Falasco et. al. Physical Review E , 90, $032131(2014)$ extends\nthe overdamped description to a generalized Langevin equation where the\neffective temperature becomes frequency dependent and consequently, for any\ntemperature measurement from a Brownian trajectory requires the knowledge of\nthis frequency dependence. We use this framework to expand on this earlier work\nand look at the first order correction to the effective temperature. The\neffective temperature is calculated from the weighted average of the\ntemperature field with the dissipation function. Further, we provide a closed\nform analytical result for effective temperature in the small as well high\nfrequency limit and using this we determine the kinetic temperature from the\ngeneralized Langevin equation and the Wiener-Khinchine theorem.",
        "positive": "A general constitutive model for dense, fine particle suspensions\n  validated in many geometries: Fine particle suspensions (such as cornstarch mixed with water) exhibit\ndramatic changes in viscosity when sheared, producing fascinating behaviors\nthat captivate children and rheologists alike. Recent examination of these\nmixtures in simple flow geometries suggests inter-granular repulsion is central\nto this effect --- for mixtures at rest or shearing slowly, repulsion prevents\nfrictional contacts from forming between particles, whereas, when sheared more\nforcefully, granular stresses overcome the repulsion allowing particles to\ninteract frictionally and form microscopic structures that resist flow.\nPrevious constitutive studies of these mixtures have focused on particular\ncases, typically limited to two-dimensional, steady, simple shearing flows. In\nthis work, we introduce a predictive and general, three-dimensional continuum\nmodel for this material, using mixture theory to couple the fluid and particle\nphases. Playing a central role in the model, we introduce a micro-structural\nstate variable, whose evolution is deduced from small-scale physical arguments\nand checked with existing data. Our space- and time-dependent model is\nimplemented numerically in a variety of unsteady, non-uniform flow\nconfigurations where it is shown to accurately capture a variety of key\nbehaviors: (i) the continuous shear thickening (CST) and discontinuous shear\nthickening (DST) behavior observed in steady flows, (ii) the time-dependent\npropagation of `shear jamming fronts', (iii) the time-dependent propagation of\n`impact activated jamming fronts', and (iv) the non-Newtonian, `running on\noobleck' effect wherein fast locomotors stay afloat while slow ones sink."
    },
    {
        "anchor": "Electro-elastic Lamb waves in dielectric plates: We study the propagation of Lamb waves in soft dielectric plates subject to\nmechanical and electrical loadings. We find explicit expressions for the\ndispersion equations in the cases of neo-Hookean and Gent dielectrics. We\nelucidate the effects of the electric field, of the thickness-to-wavelength\nratio, of pre-stress and of strain-stiffening on the wave characteristics.",
        "positive": "New method of determination of the tilt angle at a liquid crystal-glass\n  interface: We propose a polarimetric method for measuring the tilt angle of the LC\ndirector at an LC layer interface.The method involves the use of an LC cell\noperating in the mode of the total internal reflection of the ordinary wave.\nThe method is based on measuring the angle of the plane of light incidence on\nthe cell with the polarization vector of the extraordinary wave passed through\nthe cell or with the polarization vector of the ordinary wave reflected from\nthe cell. To calculate the tilt angle, the polarization azimuth of the light\nincident on the cell, which induces only the ordinary wave, can be also\nused.The method is applicable throughout the whole range of the LC director\ntilt angles."
    },
    {
        "anchor": "Role of conformational entropy in force-induced bio-polymer unfolding: A statistical mechanical description of flexible and semi-flexible polymer\nchains in a poor solvent is developed in the constant force and constant\ndistance ensembles. We predict the existence of many intermediate states at low\ntemperatures stabilized by the force. A unified response to pulling and\ncompressing forces has been obtained in the constant distance ensemble. We show\nthe signature of a cross-over length which increases linearly with the chain\nlength. Below this cross-over length, the critical force of unfolding decreases\nwith temperature, while above, it increases with temperature. For stiff chains,\nwe report for the first time \"saw-tooth\" like behavior in the force-extension\ncurves which has been seen earlier in the case of protein unfolding.",
        "positive": "[N]pT Monte Carlo Simulations of the Cluster-Crystal-Forming Penetrable\n  Sphere Model: Certain models with purely repulsive pair interactions can form cluster\ncrystals with multiply-occupied lattice sites. Simulating these models'\nequilibrium properties is, however, quite challenging. Here, we develop an\nexpanded isothermal-isobaric $[N]pT$ ensemble that surmounts this problem by\nallowing both particle number and lattice spacing to fluctuate. We apply the\nmethod with a Monte Carlo simulation scheme to solve the phase diagram of a\nprototypical cluster-crystal former, the penetrable sphere model (PSM), and\ncompare the results with earlier theoretical predictions. At high temperatures\nand densities, the equilibrium occupancy $n_{\\mathrm{c}}^{\\mathrm{eq}}$ of\nface-centered cubic (FCC) crystal increases linearly. At low temperatures,\nalthough $n_{\\mathrm{c}}^{\\mathrm{eq}}$ plateaus at integer values, the crystal\nbehavior changes continuously with density. The previously ambiguous crossover\naround $T\\sim0.1$ is resolved."
    },
    {
        "anchor": "Non-Affine Displacements Below Jamming under Athermal Quasi-Static\n  Compression: Critical properties of frictionless spherical particles below jamming are\nstudied using extensive numerical simulations, paying particular attention to\nthe non-affine part of the displacements during the athermal quasi-static\ncompression. It is shown that the squared norm of the non-affine displacement\nexhibits a power-law divergence toward the jamming transition point. A possible\nconnection between this critical exponent and that of the shear viscosity is\ndiscussed. The participation ratio of the displacements vanishes in the\nthermodynamic limit at the transition point, meaning that the non-affine\ndisplacements are localized marginally with a fractal dimension. Furthermore,\nthe distribution of the displacement is shown to have a power-law tail, the\nexponent of which is related to the fractal dimension.",
        "positive": "Molecular Mean-Field Theory of Ionic Solutions: a\n  Poisson-Nernst-Planck-Bikerman Model: We have developed a molecular mean-field theory -- fourth-order\nPoisson-Nernst-Planck-Bikerman theory -- for modeling ionic and water flows in\nbiological ion channels by treating ions and water molecules of any volume and\nshape with interstitial voids, polarization of water, and ion-ion and ion-water\ncorrelations. The theory can also be used to study thermodynamic and\nelectrokinetic properties of electrolyte solutions in batteries, fuel cells,\nnanopores, porous media including cement, geothermal brines, the oceanic\nsystem, etc. The theory can compute electric and steric energies from all atoms\nin a protein and all ions and water molecules in a channel pore while keeping\nelectrolyte solutions in the extra- and intracellular baths as a continuum\ndielectric medium with complex properties that mimic experimental data. The\ntheory has been verified with experiments and molecular dynamics data from the\ngramicidin A channel, L-type calcium channel, potassium channel, and\nsodium/calcium exchanger with real structures from the Protein Data Bank. It\nwas also verified with the experimental or Monte Carlo data of electric\ndouble-layer differential capacitance and ion activities in aqueous electrolyte\nsolutions. We give an in-depth review of the literature about the most novel\nproperties of the theory, namely, Fermi distributions of water and ions as\nclassical particles with excluded volumes and dynamic correlations that depend\non salt concentration, composition, temperature, pressure, far-field boundary\nconditions etc. in a complex and complicated way as reported in a wide range of\nexperiments. The dynamic correlations are self-consistent output functions from\na fourth-order differential operator that describes ion-ion and ion-water\ncorrelations, the dielectric response (permittivity) of ionic solutions, and\nthe polarization of water molecules with a single correlation length parameter."
    },
    {
        "anchor": "Self-Consistent Description of Local Density Dynamics in Simple Liquids.\n  The Case of Molten Lithium: The dynamic structure factor is the quantity, which can be measured by means\nof Brillouin light-scattering as well as by means of inelastic scattering of\nneutrons and X-rays. The spectral (or frequency) moments of the dynamic\nstructure factor define directly the sum rules of the scattering law. The\ntheoretical scheme formulated in this study allows one to describe the dynamics\nof local density fluctuations in simple liquids and to obtain the expression of\nthe dynamic structure factor in terms of the spectral moments. The theory\nsatisfies all the sum rules, and the obtained expression for the dynamic\nstructure factor yields correct extrapolations into the hydrodynamic limit as\nwell as into the free-particle dynamics limit. We discuss correspondence of\nthis theory with the generalized hydrodynamics and with the viscoelastic\nmodels, which are commonly used to analyze the data of inelastic neutron and\nX-ray scattering in liquids. In particular, we reveal that the postulated\ncondition of the viscoelastic model for the memory function can be directly\nobtained within the presented theory. The dynamic structure factor of liquid\nlithium is computed on the basis of the presented theory, and various features\nof the scattering spectra are evaluated. It is found that the theoretical\nresults are in agreement with inelastic X-ray scattering data.",
        "positive": "Shear induced instabilities in layered liquids: Motivated by the experimentally observed shear-induced destabilization and\nreorientation of smectic A like systems, we consider an extended formulation of\nsmectic A hydrodynamics. We include both, the smectic layering (via the layer\ndisplacement u and the layer normal p) and the director n of the underlying\nnematic order in our macroscopic hydrodynamic description and allow both\ndirections to differ in non equilibrium situations. In an homeotropically\naligned sample the nematic director does couple to an applied simple shear,\nwhereas the smectic layering stays unchanged. This difference leads to a finite\n(but usually small) angle between n and p, which we find to be equivalent to an\neffective dilatation of the layers. This effective dilatation leads, above a\ncertain threshold, to an undulation instability of the layers. We generalize\nour earlier approach [Rheol. Acta, vol.39(3), 15] and include the cross\ncouplings with the velocity field and the order parameters for orientational\nand positional order and show how the order parameters interact with the\nundulation instability. We explore the influence of various material parameters\non the instability. Comparing our results to recent experiments and molecular\ndynamic simulations, we find a good qualitative agreement."
    },
    {
        "anchor": "Phase Transitions and Relaxation Processes in Macromolecular Systems:\n  The Case of Bottle-brush Polymers: As an example for the interplay of structure, dynamics, and phase behavior of\nmacromolecular systems, this article focuses on the problem of bottle-brush\npolymers with either rigid or flexible backbones. On a polymer with chain\nlength $N_b$, side-chains with chain length $N$ are endgrafted with grafting\ndensity $\\sigma$. Due to the multitude of characteristic length scales and the\nsize of these polymers (typically these cylindrical macromolecules contain of\nthe order of 10000 effective monomeric units) understanding of the structure is\na challenge for experiment. But due to excessively large relaxation times\n(particularly under poor solvent conditions) such macromolecules also are a\nchallenge for simulation studies. Simulation strategies to deal with this\nchallenge, both using Monte Carlo and Molecular Dynamics Methods, will be\nbriefly discussed, and typical results will be used to illustrate the insight\nthat can be gained.",
        "positive": "Screw symmetry in columnar crystals: We show that the optimal packing of hard spheres in an infinitely long\ncylinder yields structures characterised by a screw symmetry. Each packing can\nbe assembled by stacking a basic unit cell ad infinitum along the length of the\ncylinder with each subsequent unit cell rotated by the same twist angle with\nrespect to the previous one. In this paper we quantitatively describe the\nnature of this screw operation for all such packings in the range 1 <= D/d <=\n2.715 and also briefly discuss their helicity."
    },
    {
        "anchor": "Direct Measurement of Lighthill's Energetic Efficiency of a Minimal\n  Magnetic Microswimmer: The realization of artificial microscopic swimmers able to propel in viscous\nfluids is an emergent research field of fundamental interest and vast\ntechnological applications. For certain functionalities, the efficiency of the\nmicroswimmer in converting the input power provided through an external\nactuation into propulsive power output can be critical. Here we use a\nmicroswimmer composed by a self-assembled ferromagnetic rod and a paramagnetic\nsphere and directly determine its swimming efficiency when it is actuated by a\nswinging magnetic field. Using fast video recording and numerical simulations\nwe fully characterize the dynamics of the propeller and identify the two\nindependent degrees of freedom which allow its propulsion. We then obtain\nexperimentally the Lighthill's energetic efficiency of the swimmer by measuring\nthe power consumed during propulsion and the energy required to translate the\npropeller at the same speed. Finally, we discuss how the efficiency of our\nmicroswimmer could be increased upon suitable tuning of the different\nexperimental parameters.",
        "positive": "Direct measurement of the effective charge in nonpolar suspensions by\n  optical tracking of single particles: We demonstrate a novel technique for the measurement of the charge carried by\na colloidal particle. The technique uses the phenomenon of the resonance of a\nparticle held in an optical tweezers trap and driven by a sinusoidal electric\nfield. The trapped particle forms a strongly damped harmonic oscillator whose\nfluctuations are a function of $\\gamma$, the ratio of the root-mean square\naverage of the electric and thermal forces on the particle. At low applied\nfields, where $\\gamma \\ll 1$, the particle is confined to the optical axis\nwhile at high fields ($\\gamma \\gg 1$) the probability distribution of the\nparticle is double-peaked. The periodically-modulated thermal fluctuations are\nmeasured with nanometer sensitivity using an interferometric position detector.\nCharges, as low as a few elementary charges, can be measured with an\nuncertainty of about 0.25 $e$. This is significantly better than previous\ntechniques and opens up new possibilities for the study of nonpolar\nsuspensions."
    },
    {
        "anchor": "Correlating the force network evolution and dynamics in slider\n  experiments: The experiments involving a slider moving on top of granular media consisting\nof photoelastic particles in two dimensions have uncovered elaborate dynamics\nthat may vary from continuous motion to crackling, periodic motion, and\nstick-slip type of behavior. We establish that there is a clear correlation\nbetween the slider dynamics and the response of the force network that\nspontaneously develop in the granular system. This correlation is established\nby application of the persistence homology that allows for formulation of\nobjective measures for quantification of time-dependent force networks. We find\nthat correlation between the slider dynamics and the force network properties\nis particularly strong in the dynamical regime characterized by well-defined\nstick-slip type of dynamics.",
        "positive": "Stimulus-responsive colloidal sensors with fast holographic readout: Colloidal spheres synthesized from polymer gels swell by absorbing molecules\nfrom solution. The resulting change in size can be monitored with nanometer\nprecision using holographic video microscopy. When the absorbate is chemically\nsimilar to the polymer matrix, swelling is driven primarily by the entropy of\nmixing, and is limited by the surface tension of the swelling sphere and by the\nelastic energy of the polymer matrix. We demonstrate though a combination of\noptical micromanipulation and holographic particle characterization that the\ndegree of swelling of a single polymer bead can be used to measure the monomer\nconcentration in situ with spatial resolution comparable to the size of the\nsphere."
    },
    {
        "anchor": "The two-angle model and the phase diagram for Chromatin: We have studied the phase diagram for chromatin within the framework of the\ntwo-angle model. Rather than improving existing models with finer details our\nmain focus of the work is getting mathematically rigorous results on the\nstructure, especially on the excluded volume effects and the effects on the\nenergy due to the long-range forces and their screening. Thus we present a\nphase diagram for the allowed conformations and the Coulomb energies.",
        "positive": "Scale-dependent non-affine elasticity of semiflexible polymer networks: The cytoskeleton of eukaryotic cells provides mechanical support and governs\nintracellular transport. These functions rely on the complex mechanical\nproperties of networks of semiflexible protein filaments. Recent theoretical\ninterest has focused on mesoscopic properties of such networks and especially\non the effect of local, non-affine bending deformations on mechanics. Here, we\nstudy the impact of local network deformations on the scale-dependent mobility\nof probe particles in entangled networks of semiflexible actin filaments by\nhigh-bandwidth microrheology. We find that micron-sized particles in these\nnetworks experience two opposing non-continuum elastic effects: entropic\ndepletion reduces the effective network rigidity, while local non-affine\ndeformations of the network substantially enhance the rigidity at low\nfrequencies. We show that a simple model of lateral bending of filaments\nembedded in a viscoelastic background leads to a scaling regime for the\napparent elastic modulus G'(\\omega) \\sim \\omega^{9/16}, closely matching the\nexperiments. These results provide quantitative evidence for how different a\nsemiflexible polymer network can feel for small objects, and they demonstrate\nhow non-affine bending deformations can be dominant for the mobility of\nvesicles and organelles in the cell."
    },
    {
        "anchor": "Gap-Dependent Hydrodynamic Lubrication in Conformal Contacts: We show that the hydrodynamic lubrication of contacting conformal surfaces\nwith a typical texture height gives rise to a universal behaviour in the\nStribeck curve in which the friction coefficient shows an anomalous power-law\ndependence on the Sommerfeld number, $\\mu \\sim S^{2/3}$. When the gap height\ndrops below the `texture length scale', deviations from $S^{2/3}$ occur, which\nmay resemble the onset of elasto-hydrodynamic and mixed lubrication. Within\nthis framework, we analyse literature data for oral processing and find\n$S^{2/3}$ scaling with deviations consistent with measured lengthscales.",
        "positive": "Reversible Formation of Thermoresponsive Binary Particle Gels with\n  Tunable Structural and Mechanical Properties: We investigate the collective behavior of suspended thermoresponsive\nmicrogels, that expel solvent and subsequently decrease in size upon heating.\nUsing a binary mixture of differently thermoresponsive microgels, we\ndemonstrate how distinctly different gel structures form, depending on the\nheating profile used. Confocal laser scanning microscopy (CLSM) imaging shows\nthat slow heating ramps yield a core-shell network through sequential gelation,\nwhile fast heating ramps yield a random binary network through homo-gelation.\nHere, secondary particles are shown to aggregate in a monolayer fashion upon\nthe first gel, which can be qualitatively reproduced through Brownian dynamics\nsimulations using a model based on a temperature-dependent interaction\npotential incorporating steric repulsion and van der Waals attraction. Through\noscillatory rheology it is shown that secondary microgel deposition enhances\nthe structural integrity of the previously formed single species gel, and the\nfinal structure exhibits higher elastic and loss moduli than its\ncompositionally identical homo-gelled counterpart. Furthermore, we demonstrate\nthat aging processes in the scaffold before secondary microgel deposition\ngovern the final structural properties of the bigel, which allows a detailed\ncontrol over these properties. Our results thus demonstrate how the temperature\nprofile can be used to finely control the structural and mechanical properties\nof these highly tunable materials."
    },
    {
        "anchor": "Layering and position-dependent diffusive dynamics of confined fluids: We study the diffusive dynamics of a hard-sphere fluid confined between\nparallel smooth hard walls. The position-dependent diffusion coefficient normal\nto the walls is larger in regions of high local packing density. High density\nregions also have the largest available volume, consistent with the fast local\ndiffusivity. Indeed, local and global diffusivities as a function of the Widom\ninsertion probability approximately collapse onto a master curve. Parallel and\naverage normal diffusivities are strongly coupled at high densities and deviate\nfrom bulk fluid behavior.",
        "positive": "Motion of microswimmers in cylindrical microchannels: Biological and artificial microswimmers often have to propel through a\nvariety of environments, ranging from heterogeneous suspending media to strong\ngeometrical confinement. Under confinement, local flow fields generated by\nmicroswimmers, and steric and hydrodynamic interactions with their environment\ndetermine the locomotion. We propose a squirmer-like model to describe the\nmotion of microswimmers in cylindrical microchannels, where propulsion is\ngenerated by a fixed surface slip velocity. The model is studied analytically\nfor cylindrical swimmer shapes, and by numerical hydrodynamics simulations for\nspherical and spheroidal shapes. For the numerical simulations, we employ the\ndissipative particle dynamics method for modelling fluid flow. Both the\nanalytical model and simulations show that the propulsion force increases with\nincreasing confinement. However, the swimming velocity under confinement\nremains lower than the swimmer speed without confinement for all investigated\nconditions. In simulations, different swimming modes (i.e. pusher, neutral,\npuller) are investigated, and found to play a significant role in the\ngeneration of propulsion force when a swimmer approaches a dead end of a\ncapillary. Propulsion generation in confined systems is local, such that the\ngenerated flow field generally vanishes beyond the characteristic size of the\nswimmer. These results contribute to a better understanding of microswimmer\nforce generation and propulsion under strong confinement, including the motion\nin porous media and in narrow channels."
    },
    {
        "anchor": "Kinetic Pathway and Micromechanics of Vesicle Fusion/Fission: Despite the wide existence of vesicles in living cells as well as their\nimportant applications like drug-delivery, the underlying mechanism of vesicle\nfusion/fission remains under debate. Here, we develop a constrained\nself-consistent field theory (SCFT) which allows tracking the shape evolution\nand free energy as a function of center-of-mass separation distance. Fusion and\nfission are described in a unified framework. Both the kinetic pathway and the\nmechanical response can be simultaneously captured. By taking vesicles formed\nby polyelectrolytes as a model system, we predict discontinuous transitions\nbetween the three morphologies: parent vesicle with a single cavity,\nhemifission/hemifusion and two separated child vesicles, as a result of\nbreaking topological isomorphism. With the increase of inter-vesicle repulsion,\nwe observe a great reduction of the cleavage energy, indicating that vesicle\nfission can be achieved without hemifission, in good agreement with simulation.\nThe force-extension relationship elucidates typical plasticity for separating\ntwo vesicles. The super extensibility in the mechanical response of vesicle is\nin stark contrast to soft particles with other morphologies such as cylinder\nand sphere.",
        "positive": "Collective excitations of degenerate Fermi gases in anisotropic\n  parabolic traps: The hydrodynamic low-frequency oscillations of highly degenerate Fermi gases\ntrapped in anisotropic harmonic potentials are investigated. Despite the lack\nof an obvious spatial symmetry the wave-equation turns out to be separable in\nelliptical coordinates, similar to a corresponding result established earlier\nfor Bose-condensates. This result is used to give the analytical solution of\nthe anisotropic wave equation for the hydrodynamic modes."
    },
    {
        "anchor": "Multifractal Analysis of Various Probability Density Functions in\n  Turbulence: The probability density functions measured by Lewis and Swinney for turbulent\nCouette-Taylor flow, observed by Bodenschatz and co-workers in the Lagrangian\nmeasurement of particle accelerations and those obtained in the DNS by Gotoh et\nal. are analyzed in excellent agreement with the theoretical formulae derived\nwith the multifractal analysis, a unified self-consistent approach based on\ngeneralized entropy, i.e., the Tsallis or the Renyi entropy. This analysis\nrests on the invariance of the Navier-Stokes equation under a scale\ntransformation for high Reynolds number, and on the assumption that the\ndistribution of the exponent $\\alpha$, introduced in the scale transformation,\nis multifractal and that its distribution function is given by taking extremum\nof the generalized entropy with the appropriate constraints. It also provides\nanalytical formula for the scaling exponents of the velocity structure function\nwhich explains quite well the measured quantities in experiments and DNS.",
        "positive": "Dynamic structure of He-Ne mixtures by MD simulation: from hydrodynamic\n  to fast and slow sound modes: Molecular dynamics results for the dynamic structure of a He0.77Ne0.23 gas\nmixture at two densities (15.8 nm-3 and 36.1 nm-3) are presented. A clear\ndescription of the crossover from hydrodynamic modes to distinct excitations\nfor the two species is obtained. The higher density data neatly show high- and\nlow-frequency branches setting on in the dispersion curve, with a rather\nlocalized transition. The lower density results remarkably agree with existing\nneutron scattering data and, differently from previous simulation studies,\ndisplay hydrodynamic behavior up to k = 2 nm-1. A smooth transition to fast\nsound is shown to take place for 2 < k / nm-1 < 5, where the present MD data\nfill the existing gap in the experimental results."
    },
    {
        "anchor": "Unusual geometric percolation of hard nanorods in the uniaxial nematic\n  liquid crystalline phase: We investigate by means of continuum percolation theory and Monte Carlo\nsimulations how spontaneous uniaxial symmetry breaking affects geometric\npercolation in dispersions of hard rod-like particles. If the particle aspect\nratio exceeds about twenty, percolation in the nematic phase can be lost upon\nadding particles to the dispersion. This contrasts with percolation in the\nisotropic phase, where a minimum particle loading is always required to obtain\nsystem-spanning clusters. For sufficiently short rods, percolation in the\nuniaxial nematic mimics that of the isotropic phase, where the addition of\nparticles always aids percolation. For aspect ratios between twenty and\ninfinity, but not including infinity, we find re-entrance behavior: percolation\nin the low-density nematic may be lost upon increasing the amount of\nnanofillers but can be re-gained by the addition of even more particles to the\nsuspension. Our simulation results for aspect ratios of 5, 10, 20, 50 and 100\nstrongly support our theoretical predictions, with almost quantitative\nagreement. We show that a new closure of the connectedness Ornstein-Zernike\nequation, inspired by Scaled Particle Theory, is more accurate than the\nLee-Parsons closure that effectively describes the impact of many-body direct\ncontacts.",
        "positive": "Criticality-related fundamental bases for new generations of gas-liquid,\n  liquid-liquid, and liquid (LE) extraction technologies: The report presents results that can be considered as the reference for\ninnovative generations of Supercritical Fluids (SCF), Liquid-Liquid (LL), and\nLiquid (L) extraction technologies. They are related to implementations of\nCritical Phenomena Physics for such applications not considered so far. For the\ngas-liquid critical point, the shift from SuperCritical to SubCritical due to\nthe additional exogenic impact of ultrasounds is indicated. For LL technology,\nthe possibility of increasing process effectiveness when operating near the\ncritical consolute point under pressure is indicated. Finally, the discovery of\nlong-range precritical-type changes of dielectric constant in linseed oil,\nstanding even 50K above the melting temperature, is presented. It suggests that\nthe extraction process linking SCF and L features, and exploring natural\ncarries such as linseed oil, is possible. The report recalls the fundamental\nbase for the extraction process via Kirkwood and Noyes-Withney relations and\npresents their implementations to critical conditions, including pressure."
    },
    {
        "anchor": "Exact predictions from Edwards ensemble vs. realistic simulations of\n  tapped narrow two-dimensional granular columns: We simulate via a Discrete Element Method the tapping of a narrow column of\ndisk under gravity. For frictionless disks, this system has a simple analytic\nexpression for the density of states in the Edwards volume ensemble. We compare\nthe predictions of the ensemble at constant compactivity against the results\nfor the steady states obtained in the simulations. We show that the steady\nstates cannot be properly described since the microstates sampled are not in\ncorrespondence with the predicted distributions, suggesting that the postulates\nof flat measure and ergodicity are, either or both, invalid for this simple\nrealization of a static granular system. However, we show that certain\nqualitative features of the volume fluctuations difficult to predict from\nsimple arguments are captured by the theory.",
        "positive": "Textures and the shapes of domains in Langmuir monolayers: Two-dimensional domains containing an XY-like order parameter exhibit\nnon-trivial internal structure and take on shapes controlled by the\nconfiguration that the order parameter adopts. The textures exhibited by the\norder parameter in such domains are controlled by the interplay between bulk\nand surface contributions to the energy. We report calculations of the internal\ntexture and the shape of such domains. These calculations lead to the\ndetermination of the equilibrium properties of two-dimensional domains, such as\nthose observed in Langmuir monolayers. This allows for the unambiguous\nexploration of the implications of experimental findings."
    },
    {
        "anchor": "Theory of Coherent and Incoherent Nuclear Spin-Dephasing in the Heart: We present an analytical theory of susceptibility induced nuclear spin\ndephasing in the capillary network of myocardium. Using a strong collision\napproach, equations are obtained for the relaxation rate of the free induction\nand the spin echo decay. Simulation and experimental data are well predicted by\nthe theory. Since paramagnetic deoxyhemoglobin as the origin of nuclear spin\ndephasing has a higher tissue concentration in myocardium supplied by a\nstenotic, i. e. significantly narrowed, coronary artery, spin dephasing might\nserve as a diagnostic tool. Our approach can be modified for capillary networks\nin other tissues than myocardium and may be applied in material science.",
        "positive": "Linear shear flow past a hemispherical droplet adhering to a solid\n  surface: This paper investigates the properties of a three dimensional shear flow\noverpassing a hemispherical droplet resting on a plane wall. The exact solution\nis computed as a function of the viscosity ratio between the droplet and the\nsurrounding fluid and generalizes the solution for the hemispherical no-slip\nbump given in an earlier paper by Price (1985). Several expressions including\nthe torque and the force acting on the drop will be considered as well as the\nimportance of the deformations on the surface for small Capillary numbers."
    },
    {
        "anchor": "Depletion zones and crystallography on pinched spheres: Understanding the interplay between ordered structures and substrate\ncurvature is an interesting problem with versatile applications, including\nfunctionalization of charged supramolecular surfaces and modern microfluidic\ntechnologies. In this work, we investigate the two-dimensional packing\nstructures of charged particles confined on a pinched sphere. By continuously\npinching the sphere, we observe cleavage of elongated scars into pleats,\nproliferation of disclinations, and subsequently, emergence of a depletion zone\nat the negatively curved waist that is completely void of particles. We\nsystematically study the geometrics and energetics of the depletion zone, and\nreveal its physical origin as a finite size effect, due to the interplay\nbetween Coulomb repulsion and concave geometry of pinched sphere. These results\nfurther our understanding of crystallography on curved surfaces, and have\nimplications in design and manipulation of charged, deformable interfaces in\nvarious applications.",
        "positive": "Enhancement of the flow of vibrated grains through narrow apertures by\n  addition of small particles: We analyze the flow and clogging of circular grains passing through a small\naperture under vibration in two dimensions. Via Discrete Element Method\nsimulations, we show that when grains smaller than the original ones are\nintroduced in the system as an additive, the net flow of the original species\ncan be significantly increased. Moreover, there is an optimal radius of the\nadditive particles that maximizes the effect. This finding may constitute the\nbasis for technological applications not only concerning the flow of granular\nmaterials but also regarding active matter, including pedestrian evacuation."
    },
    {
        "anchor": "Tops and Writhing DNA: The torsional elasticity of semiflexible polymers like DNA is of biological\nsignificance. A mathematical treatment of this problem was begun by Fuller\nusing the relation between link, twist and writhe, but progress has been\nhindered by the non-local nature of the writhe. This stands in the way of an\nanalytic statistical mechanical treatment, which takes into account thermal\nfluctuations, in computing the partition function. In this paper we use the\nwell known analogy with the dynamics of tops to show that when subjected to\nstretch and twist, the polymer configurations which dominate the partition\nfunction admit a local writhe formulation in the spirit of Fuller and thus\nprovide an underlying justification for the use of Fuller's \"local writhe\nexpression\" which leads to considerable mathematical simplification in solving\ntheoretical models of DNA and elucidating their predictions. Our result\nfacilitates comparison of the theoretical models with single molecule\nmicromanipulation experiments and computer simulations.",
        "positive": "Folding a protein with equal probability of being helix or hairpin: We explore the possibility for the native state of a protein being inherently\na multi-conformation state in an ab initio coarse-grained model. Based on the\nWang-Landau algorithm, the complete free energy landscape for the designed\nsequence 2D4X: INYWLAHAKAGYIVHWTA is constructed. It is shown that 2DX4\npossesses two nearly degenerate native states: one has a helix structure, while\nthe other has a hairpin structure and their energy difference is less than 2%\nof that of local minimums. Two degenerate native states are stabilized by an\nenergy barrier of the order 10kcal/mol. Furthermore, the hydrogen-bond and\ndipole-dipole interactions are found to be two major competing interactions in\ntransforming one conformation into the other. Our results indicate that\ndegenerate native states are stabilized by subtle balance between different\ninteractions in proteins; furthermore, for small proteins, degeneracy only\nhappens for proteins of sizes being around 18 amino acids or 40 amino acids.\nThese results provide important clues to the study of native structures of\nproteins."
    },
    {
        "anchor": "Elastic instabilities in a layered cerebral cortex: A revised axonal\n  tension model for cortex folding: We model the elasticity of the cerebral cortex as a layered material with\nbending energy along the layers and elastic energy between them in both planar\nand polar geometries. The cortex is also subjected to axons pulling from the\nunderlying white matter. Above a critical threshold force, a \"flat\" cortex\nconfiguration becomes unstable and periodic unduluations emerge, i.e. a\nbuckling instability occurs. These undulations may indeed initiate folds in the\ncortex. We identify analytically the critical force and the critical wavelength\nof the undulations. Both quantities are physiologically relevant values. Our\nmodel is a revised version of the axonal tension model for cortex folding, with\nour version taking into account the layered structure of the cortex. Moreover,\nour model draws a connection with another competing model for cortex folding,\nnamely the differential growth-induced buckling model. For the polar geometry,\nwe study the relationship between brain size and the critical force and\nwavelength to understand why small mice brains exhibit no folds, while larger\nhuman brains do, for example. Finally, an estimate of the bending rigidity\nconstant for the cortex can be made based on the critical wavelength.",
        "positive": "Granular packings of cohesive elongated particles: We report numerical results of effective attractive forces on the packing\nproperties of two-dimensional elongated grains. In deposits of non-cohesive\nrods in 2D, the topology of the packing is mainly dominated by the formation of\nordered structures of aligned rods. Elongated particles tend to align\nhorizontally and the stress is mainly transmitted from top to bottom, revealing\nan asymmetric distribution of local stress. However, for deposits of cohesive\nparticles, the preferred horizontal orientation disappears. Very elongated\nparticles with strong attractive forces form extremely loose structures,\ncharacterized by an orientation distribution, which tends to a uniform behavior\nwhen increasing the Bond number. As a result of these changes, the pressure\ndistribution in the deposits changes qualitatively. The isotropic part of the\nlocal stress is notably enhanced with respect to the deviatoric part, which is\nrelated to the gravity direction. Consequently, the lateral stress transmission\nis dominated by the enhanced disorder and leads to a faster pressure saturation\nwith depth."
    },
    {
        "anchor": "Non Gaussian information of heterogeneity in Soft Matter: Heterogeneity in dynamics in the form of non-Gaussian molecular displacement\ndistributions appears ubiquitously in soft matter. We address the\nquantification of such heterogeneity using an information-theoretic measure of\nthe distance between the actual displacement distribution and its nearest\nGaussian estimation. We explore the usefulness of this measure in two generic\nscenarios of random walkers in heterogeneous media. We show that our proposed\nmeasure leads to a better quantification of non-Gaussianity than the\nconventional ones based on moment ratios.",
        "positive": "Dynamics of pearling instability in polymersomes: the role of shear\n  membraneviscosity and spontaneous curvature: The stability of copolymer tethers is investigated theoretically.\nSelf-assembly of diblockor triblock copolymers can lead to tubular polymersomes\nwhich are known experimentallyto undergo shape instability under thermal,\nchemical and tension stresses. It leads to aperiodic modulation of the radius\nwhich evolves to assembly-line pearls connected by tinytethers. We study the\ncontributions of shear surface viscosity and spontaneous curvatureand their\ninterplay to understand the pearling instability. The performed linear\nanalysisof stability of this cylinder-to-pearls transition shows that such\nsystems are unstable if themembrane tension is larger than a finite critical\nvalue contrary to the Rayleigh-Plateau in-stability, an already known or if the\nspontaneous curvature is in a specific range whichdepends on membrane tension.\nFor the case of spontaneous curvature-induced shape insta-bility, two dynamical\nmodes are identified. The first one is analog to the tension-inducedinstability\nwith a marginal mode. Its wavenumber associated to the most unstable\nmodedecreases continuously to zero as membrane viscosity increases. The\nunexpected secondone has a finite range of unstable wavenumbers. The wavenumber\nof the most unstablemode tends to a constant as membrane viscosity increases.\nIn this mode, its growth ratebecomes independent of the bulk viscosity in the\nlimit of high membrane viscosity andbehaves as a pure viscous surface."
    },
    {
        "anchor": "Saddle-splay term induced orientational instability in nematic liquid\n  crystal cells and director fluctuations at substrates: We analyze stability of the planar orientational structure in a nematic\nliquid crystal (NLC) cell with planar anchoring conditions at both substrates.\nSpecifically, we study the instabilities of the ground state caused by surface\nelasticity at large saddle-splay elastic constant, $K_{24}$. For relatively\nsmall $K_{24}$ violating the Ericksen inequalities the theory predicts that the\ncritical fluctuation mode of the wavelength, $\\lambda_c$, will render the\nstructure unstable when the thickness of the cell is below its critical value,\n$d_c$. The parity of the critical mode changes as the twist-splay ratio\n$K_2/K_1$ is passing through the unity. Further increase of $K_{24}$ beyond the\nsecond threshold value, $4K_1K_2/(K_1+K_2)$, leads to the instability with\nrespect to the short wavelength fluctuations regardless of the cell thickness.\nWe compute the critical thickness and the critical wavelength as functions of\n$K_{24}$, the twist-splay ratio and the azimuthal anchoring strength.",
        "positive": "The Excluded Area of Superellipse Sector Particles: Superellipse sector particles (SeSPs) are segments of superelliptical curves\nthat form a tunable set of hard-particle shapes for granular and colloidal\nsystems. SeSPs allow for continuous parameterization of corner sharpness,\naspect ratio, and particle curvature; rods, circles, rectangles, and staples\nare examples of shapes SeSPs can model. We investigate the space of allowable\n(non-overlapping) configurations of two SeSPs, which depends on both the\ncenter-of-mass separation and relative orientation. Radial correlation plots of\nthe allowed configurations reveal circular regions centered at each of the\nparticle's two endpoints that indicate configurations of mutually-entangled\nparticle interactions. Simultaneous entanglement with both endpoints is\ngeometrically impossible; the overlap of these two regions therefore represents\nan excluded area in which no particles can be placed regardless of orientation.\nThe regions' distinct boundaries indicates a translational frustration with\nimplications for the dynamics of particle rearrangements (e.g. under shear).\nRepresenting translational and rotational degrees of freedom as a hypervolume,\nwe find a topological change that suggests geometric frustration arises a phase\ntransition in this space. The excluded area is a straightforward integration\nover excluded states; for arbitrary relative orientation this decreases\nsigmoidally with increasing opening aperture, with sharper SeSP corners\nresulting in a sharper decrease. Together, this work offers a path towards a\nunified theory for particle shape-control of bulk material properties."
    },
    {
        "anchor": "A Nonlinear approach to Viscoelasticity via Rational Extended\n  Thermodynamics: In the one-dimensional isothermal case, we introduce a simple model of\nnonlinear viscoelasticity within the Rational Extended Thermodynamics (RET)\nframework. The differential system is determined by the universal principles of\nRET, exhibiting symmetric hyperbolic form and ensuring the existence of smooth\nsolutions for appropriately small initial data. In the linear case, the\nequation for viscous stress reduces to the well-known Maxwell model, thereby\nrepresenting a plausible nonlinear extension of the Maxwell-type model. The\ntotal stress instead satisfies a non-linear Zener model.",
        "positive": "Data-driven quantitative modeling of bacterial active nematics: Active matter comprises individual units that convert energy into mechanical\nmotion. In many examples, such as bacterial systems and biofilament assays,\nconstituent units are elongated and can give rise to local nematic\norientational order. Such `active nematics' systems have attracted much\nattention from both theorists and experimentalists. However, despite intense\nresearch efforts, data-driven quantitative modeling has not been achieved, a\nsituation mainly due to the lack of systematic experimental data and to the\nlarge number of parameters of current models. Here we introduce a new active\nnematics system made of swarming filamentous bacteria. We simultaneously\nmeasure orientation and velocity fields and show that the complex\nspatiotemporal dynamics of our system can be quantitatively reproduced by a new\ntype of microscopic model for active suspensions whose important parameters are\nall estimated from comprehensive experimental data. This provides unprecedented\naccess to key effective parameters and mechanisms governing active nematics.\nOur approach is applicable to different types of dense suspensions and shows a\npath towards more quantitative active matter research."
    },
    {
        "anchor": "Periodic ordering of clusters and stripes in a two-dimensional lattice\n  model. I. Ground state, mean-field phase diagram and structure of the\n  disordered phases: The short-range attraction and long-range repulsion (SALR) between\nnanoparticles or macromolecules can lead to spontaneous pattern formation on\nsolid surfaces, fluid interfaces or membranes. In order to study the\nself-assembly in such systems we consider a triangular lattice model with\nnearest-neighbour attraction and third-neighbour repulsion. At the ground state\nof the model ($T=0$) the lattice is empty for small values of the chemical\npotential $\\mu$, and fully occupied for large $\\mu$. For intermediate values of\n$\\mu$ periodically distributed clusters, bubbles or stripes appear if the\nrepulsion is sufficiently strong. At the phase coexistences between the vacuum\nand the ordered cluster phases and between the cluster and the lamellar\n(stripe) phases the entropy per site does not vanish. As a consequence of this\nground state degeneracy, disordered fluid phases consisting of clusters or\nstripes are stable, and the surface tension vanishes. For $T>0$ we construct\nthe phase diagram in the mean-field approximation and calculate the correlation\nfunction in the self-consistent Brazovskii-type field theory.",
        "positive": "Magnetic wire-based sensors for the micro-rheology of complex fluids: We propose a simple micro-rheology technique to evaluate the viscoelastic\nproperties of complex fluids. The method is based on the use of magnetic wires\nof a few microns in length submitted to a rotational magnetic field. In this\nwork, the method is implemented on a surfactant wormlike micellar solution that\nbehaves as an ideal Maxwell fluid. With increasing frequency, the wires undergo\na transition between a steady and a hindered rotation regime. The study shows\nthat the average rotational velocity and the amplitudes of the oscillations\nobey scaling laws with well-defined exponents. From a comparison between model\npredictions and experiments, the rheological parameters of the fluid are\ndetermined."
    },
    {
        "anchor": "Evaporation of Lennard-Jones Fluids: Evaporation and condensation at a liquid/vapor interface are ubiquitous\ninterphase mass and energy transfer phenomena that are still not well\nunderstood. We have carried out large scale molecular dynamics simulations of\nLennard-Jones (LJ) fluids composed of monomers, dimers, or trimers to\ninvestigate these processes with molecular detail. For LJ monomers in contact\nwith a vacuum, the evaporation rate is found to be very high with significant\nevaporative cooling and an accompanying density gradient in the liquid domain\nnear the liquid/vapor interface. Increasing the chain length to just dimers\nsignificantly reduces the evaporation rate. We confirm that mechanical\nequilibrium plays a key role in determining the evaporation rate and the\ndensity and temperature profiles across the liquid/vapor interface. The\nvelocity distributions of evaporated molecules and the evaporation and\ncondensation coefficients are measured and compared to the predictions of an\nexisting model based on kinetic theory of gases. Our results indicate that for\nboth monatomic and polyatomic molecules, the evaporation and condensation\ncoefficients are equal when systems are not far from equilibrium and smaller\nthan one, and decrease with increasing temperature. For the same reduced\ntemperature $T/T_c$, where $T_c$ is the critical temperature, these two\ncoefficients are higher for LJ dimers and trimers than for monomers, in\ncontrast to the traditional viewpoint that they are close to unity for\nmonatomic molecules and decrease for polyatomic molecules. Furthermore, data\nfor the two coefficients collapse onto a master curve when plotted against a\ntranslational length ratio between the liquid and vapor phase.",
        "positive": "Characteristics of the secondary relaxation process in soft colloidal\n  suspensions: A universal secondary relaxation process, known as the Johari-Goldstein (JG)\n$\\beta$-relaxation process, appears in glass formers. It involves all parts of\nthe molecule and is particularly important in glassy systems because of its\nvery close relationship with the $\\alpha$-relaxation process. However, the\nabsence of a J-G $\\beta$-relaxation mode in colloidal glasses raises questions\nregarding its universality. In the present work, we study the microscopic\nrelaxation processes in Laponite suspensions, a model soft glassy material, by\ndynamic light scattering (DLS) experiments. $\\alpha$ and $\\beta$-relaxation\ntimescales are estimated from the autocorrelation functions obtained by DLS\nmeasurements for Laponite suspensions with different concentrations, salt\nconcentrations and temperatures. Our experimental results suggest that the\n$\\beta$-relaxation process in Laponite suspensions involves all parts of the\nconstituent Laponite particle. The ergodicity breaking time is also seen to be\ncorrelated with the characteristic time of the $\\beta$-relaxation process for\nall Laponite concentrations, salt concentrations and temperatures. The width of\nthe primary relaxation process is observed to be correlated with the secondary\nrelaxation time. The secondary relaxation time is also very sensitive to the\nconcentration of Laponite. We measure primitive relaxation timescales from the\n$\\alpha$-relaxation time and the stretching exponent ($\\beta$) by applying the\ncoupling model for highly correlated systems. The order of magnitude of the\nprimitive relaxation time is very close to the secondary relaxation time. These\nobservations indicate the presence of a J-G $\\beta$-relaxation mode for soft\ncolloidal suspensions of Laponite."
    },
    {
        "anchor": "Universality of Jamming Criticality in Overdamped Shear-Driven\n  Frictionless Disks: We investigate the criticality of the jamming transition for overdamped\nshear-driven frictionless disks in two dimensions for two different models of\nenergy dissipation: (i) Durian's bubble model with dissipation proportional to\nthe velocity difference of particles in contact, and (ii) Durian's \"mean-field\"\napproximation to (i), with dissipation due to the velocity difference between\nthe particle and the average uniform shear flow velocity. By considering\nvelocity correlations, finite-size behavior of pressure, and the pressure\nanalog of viscosity, we argue that these two models share the same critical\nbehavior.",
        "positive": "Direct numerical simulation of dispersed particles in a compressible\n  fluid: We present a direct numerical simulation method for investigating the\ndynamics of dispersed particles in a compressible solvent fluid. The validity\nof the simulation is examined by calculating the velocity relaxation of an\nimpulsively forced spherical particle with a known analytical solution. The\nsimulation also gives information about the fluid motion, which provides some\ninsight into the particle motion. Fluctuations are also introduced by random\nstress, and the validity of this case is examined by comparing the calculation\nresults with the fluctuation-dissipation theorem."
    },
    {
        "anchor": "The compensation of Gaussian curvature in developable cones is local: In this paper we use the angular deficit scheme [V. Borrelli, F. Cazals, and\nJ.-M. Morvan, {\\sl Computer Aided Geometric Design} {\\bf 20}, 319 (2003)] to\ndetermine the distribution of Gaussian curvature in developable cones (d-cones)\n[E. Cerda, S. Chaieb, F. Melo, and L. Mahadevan, {\\sl Nature} {\\bf 401}, 46\n(1999)] numerically. These d-cones are formed by pushing a thin elastic sheet\ninto a circular container. Negative Gaussian curvatures are identified at the\nrim where the sheet touches the container. Around the rim there are two narrow\nbands with positive Gaussian curvatures. The integral of the (negative)\nGaussian curvature near the rim is almost completely compensated by that of the\ntwo adjacent bands. This suggests that the Gauss-Bonnet theorem which\nconstrains the integral of Gaussian curvature globally does not explain the\nspontaneous curvature cancellation phenomenon [T. Liang and T. A. Witten, {\\sl\nPhys. Rev. E} {\\bf 73}, 046604 (2006)]. The locality of the compensation seems\nto increase for decreasing d-cone thickness. The angular deficit scheme also\nprovides a new way to confirm the curvature cancellation phenomenon.",
        "positive": "Hard rods in a cylindrical pore: the nematic-to-smectic phase transition: The effect of cylindrical confinement on the phase behaviour of a system of\nparallel hard rods is studied using Onsager's second virial theory. The hard\nrods are represented as hard cylinders of diameter $D$ and length $L$, while\nthe cylindrical pore is infinite with diameter $W$. The interaction between the\nwall and the rods is hard repulsive, and it is assumed that molecules are\nparallel to the surface of the pore (planar anchoring). In very narrow pores\n($D<W<2 D$), the structure is homogeneous and the system behaves as a\none-dimensional Tonks gas. For wider pores, inhomogeneous fluid structures\nemerge because of the lowering of the average excluded volume due to the\nwall-particle interaction. The bulk nematic-smectic A phase transition is\nreplaced by a transition between inhomogeneous nematic and smectic A phases.\nThe smectic is destabilized with respect to the nematic for decreasing pore\nwidth; this effect becomes substantial for $W<10 D$. For $W>100 D$, results for\nbulk and confined fluids agree well due to the short range effect of the wall\n($\\sim 3-4D$)."
    },
    {
        "anchor": "Mean-field scenario for the athermal creep dynamics of yield-stress\n  fluids: We develop an elasto-plastic description for the transient dynamics prior to\nsteady flow of athermally yielding materials. Our mean-field model not only\nreproduces the experimentally observed non-linear time dependence of the\nshear-rate response to an external shear-stress, but also allows for the\ndetermination of the different physical processes involved in the onset of the\nre-acceleration phase after the initial critical slowing down and a distinct\nwell defined fluidization phase. The evidenced power-law dependence of the\nfluidization time on the distance of the applied to an age dependent static\nyield stress is not universal but strongly dependent on initial conditions.",
        "positive": "(Super)Spreading and drying of trisiloxane-laden quantum dot nanofluids\n  on hydrophobic surfaces: Nanofluids hold promise for a wide range of areas of industry. However,\nunderstanding of wetting behavior and deposition formation in course of drying\nand spreading of nanofluids, particularly containing surfactants, is still\npoor. In this paper, the evaporation dynamics of quantum dot-based nanofluids\nand evaporation-driven self-assembly in nanocolloidal suspensions on\nhexamethyldisilazane-, polystyrene-, and polypropylene-coated hydrophobic\nsurfaces have been studied experimentally. Moreover, for the very first time,\nwe make a step to understanding of wetting dynamics of superspreader\nsurfactant-laden nanofluids. It was revealed that drying of surfactant-free\nquantum dot nanofluids in contrast to pure liquids undergoes not three but four\nevaporation modes including last additional pinning mode when contact angle\ndecreases whilst triple contact line is pinned by the nanocrystals. In contrast\nto previous studies, it was found out that addition of nanoparticles to aqueous\nsurfactant solutions leads to deterioration of spreading rate and to formation\nof double coffee ring. For all surfaces examined, superspreading in presence\nand absence of quantum dot nanoparticles takes place. Despite the formation of\ncoffee rings on all substrates, they have different morphology. Particularly,\nthe knot-like structures are incorporated into the ring on\nhexamethyldisilazane- and polystyrene-coated surfaces"
    },
    {
        "anchor": "Polyfluorene as a model system for space-charge-limited conduction: Ethyl-hexyl substituted polyfluorene (PF) with its high level of molecular\ndisorder can be described very well by one-carrier space-charge-limited\nconduction for a discrete set of trap levels with energy $\\sim$ 0.5 eV above\nthe valence band edge. Sweeping the bias above the trap-filling limit in the\nas-is polymer generates a new set of exponential traps, which is clearly seen\nin the density of states calculations. The trapped charges in the new set of\ntraps have very long lifetimes and can be detrapped by photoexcitation. Thermal\ncycling the PF film to a crystalline phase prevents creation of additional\ntraps at higher voltages.",
        "positive": "Phyllotaxis, disk packing and Fibonacci numbers: We consider the evolution of the packing of disks (representing the position\nof buds) that are introduced at the top of a surface which has the form of a\ngrowing stem. They migrate downwards, while conforming to three principles,\napplied locally: dense packing, homogeneity and continuity. We show that spiral\nstructures characterised by the widely observed Fibonacci sequence\n(1,1,2,3,5,8,13...), as well as related structures, occur naturally under such\nrules. Typical results are presented in a animation."
    },
    {
        "anchor": "Phase diagram of a two-dimensional lattice gas model of a ramp system: Using Monte Carlo Simulation and fundamental measure theory we study the\nphase diagram of a two-dimensional lattice gas model with a nearest neighbor\nhard core exclusion and a next-to-nearest neighbors finite repulsive\ninteraction. The model presents two competing ranges of interaction and, in\ncommon with many experimental systems, exhibits a low density solid phase,\nwhich melts back to the fluid phase upon compression. The theoretical approach\nis found to provide a qualitatively correct picture of the phase diagram of our\nmodel system.",
        "positive": "Dynamic self-consistent field approach for studying kinetic processes in\n  multiblock copolymer melts: The self-consistent field theory is a popular and highly successful\ntheoretical framework for studying equilibrium (co)polymer systems at the\nmesoscopic level. Dynamic density functionals allow one to use this framework\nfor studying dynamical processes in the diffusive, non-inertial regime. The\ncentral quantity in these approaches is the mobility function, which describes\nthe effect of chain connectivity on the nonlocal response of monomers to\nthermodynamic driving fields. In a recent study [Mantha et al, Macromolecules\n53, 3409 (2020)], we have developed a method to systematically construct\nmobility functions from reference fine-grained simulations. Here we focus on\nmelts of linear chains in the Rouse regime and show how the mobility functions\ncan be calculated semi-analytically for multiblock copolymers with arbitrary\nsequences without resorting to simulations. In this context, an accurate\napproximate expression for the single-chain dynamic structure factor is\nderived. Several limiting regimes are discussed. Then we apply the resulting\ndensity functional theory to study ordering processes in a two-length scale\nblock copolymer system after instantaneous quenches into the ordered phase.\nDifferent dynamical regimes in the ordering process are identified: At early\ntimes, the ordering on short scales dominates; at late times, the ordering on\nlarger scales takes over. For large quench depths, the system does not\nnecessarily relax into the true equilibrium state. Our density functional\napproach could be used for the computer-assisted design of quenching protocols\nin order to create novel nonequilibrium materials."
    },
    {
        "anchor": "Brittle Crack Roughness in Three-Dimensional Beam Lattices: The roughness exponent is reported in numerical simulations with a\nthree-dimensional elastic beam lattice. Two different types of disorder have\nbeen used to generate the breaking thresholds, i.e., distributions with a tail\ntowards either strong or weak beams. Beyond the weak disorder regime a\nuniversal exponent of 0.59(1) is obtained. This is within the range 0.4-0.6\nreported experimentally for small scale quasi-static fracture, as would be\nexpected for media with a characteristic length scale.",
        "positive": "Degenerate states, emergent dynamics and fluid mixing by magnetic rotors: We investigate the collective motion of magnetic rotors suspended in a\nviscous fluid under an uniform rotating magnetic field. The rotors are\npositioned on a square lattice, and low Reynolds hydrodynamics is assumed. For\na $3 \\times 3$ array of magnets, we observe three characteristic dynamical\npatterns as the external field strength is varied: a synchronized pattern, an\noscillating pattern, and a chessboard pattern. The relative stability of these\ndepends on the competition between the energy due to the external magnetic\nfield and the energy of the magnetic dipole-dipole interactions among the\nrotors. We argue that the chessboard pattern can be understood as an\nalternation in the stability of two degenerate states, characterized by striped\nand spin-ice configurations, as the applied magnetic field rotates. For larger\narrays, we observe propagation of slip waves that are similar to metachronal\nwaves. The rotor arrays have potential as microfluidic devices that can mix\nfluids and create vortices of different sizes."
    },
    {
        "anchor": "Effects of coordination and pressure on sound attenuation, boson peak\n  and elasticity in amorphous solids: Connectedness and applied stress strongly affect elasticity in solids. In\nvarious amorphous solids, mechanical stability can be lost either by reducing\nconnectedness or by increasing pressure. We present an effective medium theory\nof elasticity that extends previous approaches by incorporating the effect of\ncompression, of amplitude $e$, allowing one to describe quantitative features\nof sound propagation, transport, the boson peak, and elastic moduli near the\nelastic instability occurring at a compression $e_c$. The theory disentangles\nseveral frequencies characterizing the vibrational spectrum: the onset\nfrequency $\\omega_0\\sim \\sqrt{e_c-e}$ where strongly-scattered modes appear in\nthe vibrational spectrum, the pressure-independent frequency $\\omega_*$ where\nthe density of states displays a plateau, the boson peak frequency\n$\\omega_{BP}$, and the Ioffe-Regel frequency $\\omega_{IR}$ where scattering\nlength and wavelength become equal. We predict that sound attenuation crosses\nover from $\\omega^4$ to $\\omega^2$ behaviour at $\\omega_0$. We predict that a\nfrequency-dependent length scale $l_s(\\omega)$ and speed of sound $\\nu(\\omega)$\ncharacterize vibrational modes, and could be extracted from scattering data.\nOne key result is the prediction of a flat diffusivity above $\\omega_0$, in\nagreement with previously unexplained observations. We find that the shear\nmodulus does not vanish at the elastic instability, but drops by a factor of 2.\nWe check our predictions in packings of soft particles and study the case of\ncovalent networks and silica. Overall, our approach unifies sound attenuation,\ntransport and length scales entering elasticity in a single framework where\ndisorder is not the main parameter controlling the boson peak, in agreement\nwith observations. This framework leads to a phase diagram where various\nglasses can be placed, connecting microscopic structure to vibrational\nproperties.",
        "positive": "Three-dimensional granular flow continuum modeling via material point\n  method with hyperelastic nonlocal granular fluidity: The accurate and efficient modeling of granular flows and their interactions\nwith external bodies is an open research problem. Continuum methods can be used\nto capture complexities neglected by terramechanics models without the\ncomputational expense of discrete element methods. Constitutive models and\nnumerical solvers are the two primary aspects of the continuum methods. The\nviscoplastic size-dependent non-local granular fluidity (NGF) constitutive\nmodel has successfully provided a quantitative description of experimental\nflows in many different configurations in literature. This research develops a\nnumerical approach, within a hyperelasticity framework, for implementing the\ndynamical form of NGF in three-dimensional material point method (3D MPM, an\nappropriate numerical solver for granular flow modeling). This approach is\nthermodynamically consistent to conserve energy, and the dynamical form\nincludes the nonlocal effect of flow cessation. Excavation data, both\nquantitative measurements and qualitative visualization, are collected\nexperimentally via our robotic equipment to evaluate the model with respect to\nthe flow geometry as well as interaction forces. The results are further\ncompared with the results from a recent modified plastic Drucker-Prager\nconstitutive model, and in other configurations including wheel-soil\ninteractions, a gravity-driven silo, and Taylor-Couette flow."
    },
    {
        "anchor": "On the quantum dynamics of Davydov solitons in protein $\u03b1$-helices: The transport of energy inside protein $\\alpha$-helices is studied by\nderiving a system of quantum equations of motion from the Davydov Hamiltonian\nwith the use of the Schr\\\"odinger equation and the generalized Ehrenfest\ntheorem. Numerically solving the system of quantum equations of motion for\ndifferent initial distributions of the amide I energy over the peptide groups\nconfirmed the generation of both moving or stationary Davydov solitons. In this\nsimulation the soliton generation, propagation, and stability were found to be\ndependent on the symmetry of the exciton-phonon interaction Hamiltonian and the\ninitial site of application of the exciton energy.",
        "positive": "General model for segregation forces in flowing granular mixtures: Particle segregation in dense flowing size-disperse granular mixtures is\ndriven by gravity and shear, but predicting the associated segregation force\ndue to both effects has remained an unresolved challenge. Here, a model of the\ncombined gravity- and kinematics-induced segregation force on a single intruder\nparticle is integrated with a model of the concentration dependence of the\ngravity-induced segregation force. The result is a general model of the net\nparticle segregation force in flowing size-bidisperse granular mixtures. Using\ndiscrete element method simulations for comparison, the model correctly\npredicts the segregation force for a variety of mixture concentrations and flow\nconditions in both idealized and natural shear flows."
    },
    {
        "anchor": "Success and breakdown of Tanner's law for drops of dense granular\n  suspensions: The spreading of viscous drops of density-matched suspensions on a solid\nsurface is experimentally investigated at the global drop scale. The spreading\ndynamics still obeys Tanner's law provided one uses an effective viscosity\nwhich happens to be smaller than the bulk viscosity of the suspension. When the\nheight of the drop is of the order of the particle size, Tanner's law breaks\ndown as the particles start to freeze and the pure fluid drains out of the\nsolid matrix.",
        "positive": "Conformational Properties of an Adsorbed Charged Polymer: The behavior of a strongly charged polymer adsorbed on an oppositely charged\nsurface of low-dielectric constant is formulated by the functional integral\nmethod. By separating the translational, conformational, and fluctuational\ndegrees of freedom, the scaling behaviors for both the height of the polymer\nand the thickness of the diffusion layer are determined. Unlike the results\npredicted by scaling theory, we identified the continuous crossover from the\nweak compression to the compression regime. All teh analytical results are\nfound to be consistent with Monte-Carlo simulations. Finally, an alternative\n(operational) definition of a charged polymer adsorption is proposed."
    },
    {
        "anchor": "Interactions in protein solutions close to liquid-liquid phase\n  separation: Ethanol reduces attractions via changes of the dielectric\n  solution properties: Ethanol is a common protein crystallization agent, precipitant, and\ndenaturant, but also alters the dielectric properties of solutions. While\nethanol-induced unfolding is largely ascribed to its hydrophobic parts, its\neffect on protein phase separation and inter-protein interactions remains\npoorly understood. Here, the effects of ethanol and NaCl on the phase behavior\nand interactions of protein solutions are studied in terms of the metastable\nliquid-liquid phase separation (LLPS) and the second virial coefficient $B_2$\nusing lysozyme solutions. Determination of the phase diagrams shows that the\ncloud-point temperatures are reduced and raised by the addition of ethanol and\nsalt, respectively. The observed trends can be explained using the extended law\nof corresponding states as changes of $B_2$. The results for $B_2$ agree\nquantitatively with those of static light scattering and small-angle X-ray\nscattering experiments. Furthermore, $B_2$ values calculated based on\ninter-protein interactions described by the Derjaguin--Landau--Verwey--Overbeek\n(DLVO) potential and considering the dielectric solution properties and\nelectrostatic screening due to the ethanol and salt content quantitatively\nagree with the experimentally observed $B_2$ values.",
        "positive": "Scale-free channeling patterns near the onset of erosion of sheared\n  granular beds: Erosion shapes our landscape and occurs when a sufficient shear stress is\nexerted by a fluid on a sedimented layer. What controls erosion at a\nmicroscopic level remains debated, especially near the threshold forcing where\nit stops. Here we study experimentally the collective dynamics of the moving\nparticles, using a set-up where the system spontaneously evolves toward the\nerosion onset. We find that the spatial organization of the erosion flux is\nheterogeneous in space, and occurs along channels of local flux $\\sigma$ whose\ndistribution displays scaling near threshold and follows $P(\\sigma)\\sim\nJ/\\sigma$, where $J$ is the mean erosion flux. Channels are strongly correlated\nin the direction of forcing but not in the transverse direction. We show that\nthese results quantitatively agree with a model where the dynamics is governed\nby the competition of disorder (which channels mobile particles) and particle\ninteractions (which reduces channeling). These observations support that for\nlaminar flows, erosion is a dynamical phase transition which shares similarity\nwith the plastic depinning transition occurring in dirty superconductors. The\nmethodology we introduce here could be applied to probe these systems as well."
    },
    {
        "anchor": "Sedimentation of strongly and weakly charged colloidal particles:\n  Prediction of fractional density dependence: We report on calculations of the reduced sedimentation velocity $U/U_{0}$ in\nhomogenous suspensions of strongly and weakly charged colloidal spheres as a\nfunction of particle volume fraction $\\phi$. For dilute suspensions of strongly\ncharged spheres at low salinity, $U/U_{0}$ is well represented by the\nparametric form $1-p\\phi^\\alpha$ with a fractional exponent $\\alpha=1/3$ and a\nparameter $p\\simeq 1.8$, which is essentially independent from the macroion\ncharge $Z$. This non-linear volume fraction dependence can be quantitatively\nunderstood in terms of a model of effective hard spheres with $\\phi$-dependent\ndiameter. For weakly charged spheres in a deionized solvent, we show that the\nexponent $\\alpha$ can be equal to 1/2, if an expression for $U/U_0$ given by\nPetsev and Denkov [J. Colloid Interface Sci. 149, 329 (1992)] is employed. We\nfurther show that the range of validity of this expression is limited to very\nsmall values of $\\phi$ and $Z$, which are probably not accessible in\nsedimentation experiments. The presented results might also hold for other\nsystems like spherical proteins or ionic micelles.",
        "positive": "A microfluidic method for passive trapping of sperms in microstructures: Sperm motility is a prerequisite for male fertility. Enhancing the\nconcentration of motile sperms in assisted reproductive technologies - for\nhuman and animal reproduction - is typically achieved through aggressive\nmethods such as centrifugation. Here we propose a passive technique for the\namplification of motile sperm concentration, with no externally imposed forces\nor flows. The technique is based upon the disparity between probability rates,\nfor motile cells, of entering in and escaping from complex structures. The\neffectiveness of the technique is demonstrated in microfluidic experiments with\nmicrostructured devices, comparing the trapping power in different geometries.\nIn these micro-traps we observe an enhancement of cells concentration close to\n10, with a contrast between motile and non-motile increased by a similar\nfactor. Simulations of suitable interacting model sperms in realistic\ngeometries reproduce quantitatively the experimental results, extend the range\nof observations and highlight the ingredients that are key to optimal trap\ndesign."
    },
    {
        "anchor": "Viscous lock-exchange in rectangular channels: In a viscous lock-exchange gravity current, which describes the reciprocal\nexchange of two fluids of different densities in a horizontal channel, the\nfront between two Newtonian fluids spreads as the square root of time. The\nresulting diffusion coefficient reflects the competition between the buoyancy\ndriving effect and the viscous damping, and depends on the geometry of the\nchannel. This lock-exchange diffusion coefficient has already been computed for\na porous medium, a 2D Stokes flow between two parallel horizontal boundaries\nseparated by a vertical height, H, and, recently, for a cylindrical tube. In\nthe present paper, we calculate it, analytically, for a rectangular channel\n(horizontal thickness b, vertical height, H) of any aspect ratio (H/b) and\ncompare our results with experiments in horizontal rectangular channels for a\nwide range of aspect ratios (1/10-10). We also discuss the 2D Stokes-Darcy\nmodel for flows in Hele-Shaw cells and show that it leads to a rather good\napproximation, when an appropriate Brinkman correction is used.",
        "positive": "Evidence of reverse and intermediate size segregation in dry granular\n  flows down a rough incline: In a dry granular flow, size segregation behave differently for a mixture\ncontaining a few large beads with a size ratio (S) above 5 (Thomas, Phys.Rev.E\n62,96(2000)). For moderate large S, large beads migrate to an intermediate\ndepth in the bed: this is called intermediate segregation. For the largest S,\nlarge beads migrate to the bottom: this is called reverse segregation (in\ncontrast with surface segregation). As the reversal and intermediate depth\nvalues depend on the bead fraction, this numerical study mainly uses a single\nlarge tracer. Small fractions are also computed showing the link between a\ntracer behavior and segregation process. For half-filled rotating drum and for\nrough incline, two and three (3D) dimensional cases are studied. In the\ntumbler, trajectories of a large tracer show that it reaches a constant depth\nduring the flow. For large S, this depth is intermediate with a progressive\nsinking when S increases. Largest S correspond to tracers at the bottom of the\nflow. All 3D simulation are in quantitative agreement with the experiments. In\nthe flow down an incline, a large tracer reaches an equilibrium depth during\nflow. For large S, its depth is intermediate, inside the bed. For the largest\nS, its depth is reverse, near the bottom. Results are slightly different for\nthin or thick flow. For 3D thick flows, the reversal between surface and bottom\npositions occurs within a short range of S: no tracer stabilizes near\nmid-height and two reachable intermediate depth layers exist, below the surface\nand above the bottom. For 3D thin flows, all intermediate depths are reachable,\ndepending on S. The numerical study of larger tracer fractions (5-10%) shows\nthe 3 segregation patterns (surface, intermediate, reverse) corresponding to\nthe 3 types of equilibrium depth. The reversal is smoother than for a single\ntracer. It happens around S=4.5, in agreement with experiments."
    },
    {
        "anchor": "Singularity identification for the characterization of topology,\n  geometry, and motion of nematic disclination lines: We introduce a characterization of disclination lines in three dimensional\nnematic liquid crystals as a tensor quantity related to the so called rotation\nvector around the line. This quantity is expressed in terms of the nematic\ntensor order parameter $\\mathbf{Q}$, and shown to decompose as a dyad involving\nthe tangent vector to the disclination line and the rotation vector. Further,\nwe derive a kinematic law for the velocity of disclination lines by connecting\nthis tensor to a topological charge density as in the Halperin-Mazenko\ndescription of defects in vector models. Using this framework, analytical\npredictions for the velocity of interacting line disclinations and of\nself-annihilating disclination loops are given and confirmed through numerical\ncomputation.",
        "positive": "Testing models for structural relaxation of viscous liquids by\n  temperature jump experiments: Based on the Tool-Narayanaswami formalism for structural relaxation we\npropose an experiment which independent of the relaxation time distribution\ndetermines the structural relaxation rate by subtracting relaxations following\ntwo different temperature jumps. In particular, the experiment makes it\npossible to evaluate the relaxation rate immediately following a temperature\njump - thus allowing one to distinguish the entropy model from others."
    },
    {
        "anchor": "Force calculation on walls and embedded particles in multiparticle\n  collision dynamics simulations: Colloidal solutions posses a wide range of time and length scales, so that it\nis unfeasible to keep track of all of them within a single simulation. As a\nconsequence some form of coarse-graining must be applied. In this work we use\nthe Multi-Particle Collision Dynamics scheme. We describe a particular\nimplementation of no-slip boundary conditions upon a solid surface, capable of\nproviding correct force s on the solid bypassing the calculation of the\nvelocity profile or the stre ss tensor in the fluid near the surface. As an\napplication we measure the friction on a spherical particle, when it is placed\nin a bulk fluid and when it is confined in a slit. We show that the\nimplementation of the no-slip boundary conditions leads to an enhanced Ensko g\nfriction, which can be understood analytically. Because of the long-range\nnature of hydrodynamic interactions, the Stokes friction obtained from the\nsimulations is sensitive of the simulation box size. We address this topic for\nthe slit geometry, showing that that the dependence on the system size differs\nvery much from what is expected in a 3D system, where periodic boundary\nconditions are used in all directions.",
        "positive": "Second-virial theory for shape-persistent living polymers templated by\n  discs: Living polymers composed of non-covalently bonded building blocks with weak\nbackbone flexibility may self-assemble into thermoresponsive lyotropic liquid\ncrystals. We demonstrate that the reversible polymer assembly and phase\nbehavior can be controlled by the addition of (non-adsorbing) rigid colloidal\ndiscs which act as an entropic reorienting ``template\" onto the supramolecular\npolymers. Using a particle-based second-virial theory that correlates the\nvarious entropies associated with the polymers and discs, we demonstrate that\nsmall fractions of discotic additives promote the formation of a polymer\nnematic phase. At larger disc concentrations, however, the phase is disrupted\nby collective disc alignment in favor of a discotic nematic fluid in which the\npolymers are dispersed anti-nematically. We show that the anti-nematic\narrangement of the polymers generates a non-exponential molecular-weight\ndistribution and stimulates the formation of oligomeric species. At sufficient\nconcentrations the discs facilitate a liquid-liquid phase separation which can\nbe brought into simultaneously coexistence with the two fractionated nematic\nphases, providing evidence for a four-fluid coexistence in reversible\nshape-dissimilar hard-core mixtures without cohesive interparticle forces. We\nstipulate the conditions under which such a phenomenon could be found in\nexperiment."
    },
    {
        "anchor": "Viscoelastic and elastomeric active matter: Linear instability and\n  nonlinear dynamics: We consider a continuum model of active viscoelastic matter, whereby an\nactive nematic liquid-crystal is coupled to a minimal model of polymer dynamics\nwith a viscoelastic relaxation time $\\tau_C$. To explore the resulting\ninterplay between active and polymeric dynamics, we first generalise a linear\nstability analysis (from earlier studies without polymer) to derive criteria\nfor the onset of spontaneous heterogeneous flows (strain rate) and/or\ndeformations (strain). We find two modes of instability. The first is a viscous\nmode, associated with strain rate perturbations. It dominates for relatively\nsmall values of $\\tau_C$ and is a simple generalisation of the instability\nknown previously without polymer. The second is an elastomeric mode, associated\nwith strain perturbations, which dominates at large $\\tau_C$ and persists even\nas $\\tau_C\\to\\infty$. We explore the novel dynamical states to which these\ninstabilities lead by means of direct numerical simulations. These reveal\noscillatory shear-banded states in 1D, and activity-driven turbulence in 2D\neven in the elastomeric limit $\\tau_C\\to\\infty$. Adding polymer can also have\ncalming effects, increasing the net throughput of spontaneous flow along a\nchannel in a new type of \"drag-reduction\". Finally the effect of including\nstrong, antagonistic coupling between nematic and polymer is examined\nnumerically, revealing a rich array of spontaneously flowing states.",
        "positive": "Anomalous properties of heat diffusion in living tissue caused by\n  branching artery network. Qualitative description: We analyze the effect of blood flow through large arteries of peripheral\ncirculation on heat transfer in living tissue. Blood flow in such arteries\ngives rise to fast heat propagation over large scales, which is described in\nterms of heat superdiffusion. The corresponding bioheat heat equation is\nderived. In particular, we show that under local strong heating of a small\ntissue domain the temperature distribution inside the surrounding tissue is\naffected substantially by heat superdiffusion."
    },
    {
        "anchor": "Evolution of a Network of Vortex Loops in the Turbulent Superfluid\n  Helium; Derivation of the Vinen Equation: The evolution a network of vortex loops due to the fusion and breakdown in\nthe turbulent superfluid helium is studied. We perform investigation on the\nbase of the \"rate equation\" for the distribution function $n(l)$ of number of\nloops in space of their length $l$. There are two mechanisms for change of\nquantity $n(l)$. Firstly, the function changes due to deterministic process of\nmutual friction, when the length grows or decreases depending on orientation.\nSecondly, the change of $n(l)$ occurs due to random events when the loop\ncrosses itself breaking down into two daughter or two loops collide merging\ninto one larger loop. Accordingly the \"rate equation\" includes the \"collision\"\nterm collecting random processes of fusion and breakdown and the deterministic\nterm. Assuming, further, that processes of random colliding are fastest we are\nin position to study more slow processes related to deterministic term. In this\nway we study the evolution of full length of vortex loops per unit volume-so\ncalled vortex line density ${\\cal L}(t)$. It is shown this evolution to obey\nthe famous Vinen equation. In conclusion we discuss properties of the Vinen\nequation from the point of view of the developed approach.",
        "positive": "Nonequilibrium Transport Induced by Biological Nanomachines: Biological nanomachines are nanometer-size macromolecular complexes that\ncatalyze chemical reactions in the presence of substrate molecules. The\ncatalytic functions carried out by such nanomachines in the cytoplasm, and\nbiological membranes are essential for cellular metabolism and homeostasis.\nDuring catalytic reactions, enzymes undergo conformational changes induced by\nsubstrate binding and product release. In recent years, these conformational\ndynamics have been considered to account for the nonequilibrium transport\nphenomena such as diffusion enhancement, chemotaxis, and substantial change in\nrheological properties, which are observed in biological systems. In this\nreview article, we shall give an overview of the recent theoretical and\nexperimental investigations that deal with nonequilibrium transport phenomena\ninduced by biological nanomachines such as enzymes or proteins."
    },
    {
        "anchor": "The removal of the polarization errors in low frequency dielectric\n  spectroscopy: Electrode polarization error is the biggest problem when measuring the low\nfrequency dielectric properties of electrolytes or suspensions of particles,\nincluding cells, in electrolytes. We present a simple and robust method to\nremove the polarization error, which we demonstrate to work on weak and strong\nionic electrolytes as well as on cell suspensions. The method assumes no\nparticular behavior of the electrode polarization impedance; it makes use of\nthe fact that the effect dies out with frequency. The method allows for direct\nmeasurement of the polarization impedance, whose behavior with the applied\nvoltages, electrode distance and ionic concentration is investigated.",
        "positive": "Demixing in binary mixtures with differential diffusivity at high\n  density: Spontaneous phase separation, or demixing, is important in biological\nphenomena such as cell sorting. In particle-based models, an open question is\nwhether differences in diffusivity can drive such demixing. While\ndifferential-diffusivity-induced phase separation occurs in mixtures with a\npacking fraction up to $0.7$ [Weber et al. Phys Rev Lett 2016], here we\ninvestigate whether demixing persists at even higher densities relevant for\ncells. For particle packing fractions between $0.7$ and $1.0$ the system\ndemixes, but at packing fractions above unity the system remains mixed,\nexposing re-entrant behavior in the phase diagram. We also find that a\nconfluent Voronoi model for tissues does not phase separate, consistent with\nthe highest-density particle-based simulations."
    },
    {
        "anchor": "X-ray absorption signatures of the molecular environment in water and\n  ice: The x-ray absorption spectra of water and ice are calculated with a many-body\napproach for electron-hole excitations. The experimental features, including\nthe small effects of temperature change in the liquid, are quantitatively\nreproduced from molecular configurations generated by ab-initio molecular\ndynamics. The spectral difference between the solid and the liquid is due to\ntwo major short range order effects. One, due to breaking of hydrogen bonds,\nenhances the pre-edge intensity in the liquid. The other, due to a non-bonded\nmolecular fraction in the first coordination shell, affects the main spectral\nedge in the conversion of ice to water. This effect may not involve hydrogen\nbond breaking as shown by experiment in high-density amorphous ice.",
        "positive": "Orientational dynamics of colloidal ribbons self-assembled from\n  microscopic magnetic ellipsoids: We combine experiments and theory to investigate the orientational dynamics\nof dipolar ellipsoids, which self-assemble into elongated ribbon-like\nstructures due to the presence in each particle of a permanent magnetic moment\nperpendicular to the long axis. Monodisperse hematite ellipsoids are\nsynthesized via sol-gel technique, and arrange into ribbons in presence of\nstatic or time-dependent magnetic fields. We find that under an oscillating\nfield, the ribbons reorient perpendicular to the field direction, in contrast\nwith the behaviour observed under a static field. This observation is explained\ntheoretically by treating a chain of interacting ellipsoids as a single\nparticle with an orientational and demagnetizing field energy. The model allows\ndescribing the orientational behaviour of the chain and captures well its\ndynamics at different strengths of the actuating field. The understanding of\nthe complex dynamics and assembly of anisotropic magnetic colloids is a\nnecessary step towards controlling the structure formation which has direct\napplications in different fluid-based microscale technologies."
    },
    {
        "anchor": "From polymers to proteins: effect of side chains and broken symmetry in\n  the formation of secondary structures within a Wang-Landau approach: We study the equilibrium properties of a single flexible homopolymers where\nconsecutive monomers are represented by impenetrable hard spherical beads\ntangential to each other, and non-consecutive monomers interact via a\nsquare-well potential. To this aim, we use both replica exchange canonical\nsimulations and micro-canonical Wang-Landau techniques. We perform a close\ncomparative analysis of the corresponding results, and find perfect agreement\nbetween the two methods as well as the past results. The model is then refined\nin two different directions. By allowing partial overlapping between\nconsecutive beads, we break the spherical symmetry and thus provide a severe\nconstraint on the possible conformations of the chain. This leads to a single\nhelix or a double helix ground state, depending on the range of the\ninteractions. Alternatively, we introduce additional spherical beads at\nspecific positions to represent the steric hindrance of the side chains in real\nproteins. The ground state in this case is found to be again a globule, thus\nshowing that contrary to some recent suggestions, side chains alone are not\nsufficient to insure a protein-like structure. Finally, we show that a\ncombination of the above two effects increases the stability of the obtaining\nsecondary structures, in agreement with previous results. The fundamental role\nplayed by the range of the square-well attraction is highlighted, and it is\nshown that they play a role similar to that found in simple liquids and\npolymers. Perspectives in terms of protein folding are finally discussed.",
        "positive": "Discontinuous Crack Fronts of Three-Dimensional Fractures: The relation between fracture surface morphology and the three-dimensional\nstructure of crack fronts is investigated through direct observation of brittle\ncracks in gels. A key notion in this investigation is the discontinuity of the\ncrack front, whose advancement creates the fracture surface. We discuss the\nsignificance of our findings in the studies of general three-dimensional\nbrittle fractures."
    },
    {
        "anchor": "Materials of the round table ``Phase transitions and critical phenomena:\n  past, present, and future\": The paper contains materials of the discussion concerning phase transitions\nand critical phenomena which took place during the Workshop on modern problems\nof soft matter theory (Aug. 27 -- Aug. 31, 2000, Lviv, Ukraine).",
        "positive": "Periodic training of creeping solids: We consider disordered solids in which the microscopic elements can deform\nplastically in response to stresses on them. We show that by driving the system\nperiodically, this plasticity can be exploited to train in desired elastic\nproperties, both in the global moduli and in local \"allosteric\" interactions.\nPeriodic driving can couple an applied \"source\" strain to a target strain over\na path in the energy landscape. This coupling allows control of the system's\nresponse even at large strains well into the nonlinear regime, where it can be\ndifficult to achieve control simply by design."
    },
    {
        "anchor": "Hydrodynamics for a granular gas from an exactly solvable kinetic model: A simple exactly solvable kinetic model for the non-linear inelastic hard\nsphere Boltzmann equation is used to explore the relevance of hydrodynamics for\na granular gas. The equation predicts a non-trivial homogeneous cooling state\n(HCS), including algebraic decay at large velocities. The linearized kinetic\nequation for small perturbations about the HCS is solved exactly. It is shown\nthat the hydrodynamic excitations exist in this linearized dynamics, and their\ndetailed form is shown to agree with results from the Chapman-Enskog method up\nthrough Navier-Stokes order. The existence of the hydrodynamic modes at short\nwavelengths, far beyond Navier-Stokes order is demonstrated as well. Finally,\nthe precise sense in which the hydrodynamic excitations dominate the dynamics\nat long times is described.",
        "positive": "Bidisperse and polydisperse suspension rheology at large solid fraction: At the same solid volume fraction, bidisperse and polydisperse suspensions\ndisplay lower viscosities, and weaker normal stress response, compared to\nmonodisperse suspensions. The reduction of viscosity associated with size\ndistribution can be explained by an increase of the maximum flowable, or\njamming, solid fraction ${\\phi}_m$. In this work, dense suspensions are\nsimulated under strong shearing, where thermal motion and repulsive forces are\nnegligible, but we allow for particle contact with a mild frictional\ninteraction with interparticle friction coefficient of ${\\mu} = 0.2$. Aspects\nof bidisperse suspension rheology are first revisited to establish that the\napproach reproduces established trends; the study of bidisperse suspensions at\nsize ratios of large to small particle radii of $\\delta = 2$ to 4 shows that a\nminimum in the viscosity occurs for ${\\zeta}$ slightly above 0.5, where $\\zeta\n= {\\phi}_l/{\\phi}$ is the fraction of the total solid volume occupied by the\nlarge particles. The simple shear flows of polydisperse suspensions with\ntruncated normal and log normal size distributions, and bidisperse suspensions\nwhich are statistically equivalent with these polydisperse cases up to third\nmoment of the size distribution, are simulated and the rheologies are\nextracted. Prior work shows that such distributions with equivalent low-order\nmoments have similar ${\\phi}_m$, and the rheological behaviors of normal, log\nnormal and bidisperse cases are shown to be in close agreement for a wide range\nof standard deviation in particle size, with standard correlations which are\nfunctionally dependent on ${\\phi}/{\\phi}_m$ providing excellent agreement with\nthe rheology found in simulation. The close agreement of both viscosity and\nnormal stress response between bi- and polydisperse suspensions demonstrates\nthe controlling influence of the maximum packing fraction in noncolloidal\nsuspensions"
    },
    {
        "anchor": "Precise characterization of micro rotors in optical tweezers: We present an optical tweezer based study of rotation of microscopic objects\nwith shape asymmetry. Thermal fluctuations and rotations are simultaneously\nmonitored through laser back scattering. The rotation results in a modulation\nin intensity of the back scattered light incident on a quadrant photo detector.\nThis results in the manifestation of peaks at a fundamental rotational\nfrequency and at integer harmonics, superimposed on a modified Lorentzian in\nthe power spectrum. The multiple peaks indicate that the rotations are periodic\nbut with varying angular velocity. We demonstrate the use of video microscopy\nfor characterization of low reflectivity rotors, such as biological cells. The\nmethods also enable a measurement of the average torque on the rotor, and in\nprinciple, can reveal information about its principal moments of inertia, and\nthe role of hydrodynamics at micron levels",
        "positive": "Microscale swimming: The molecular dynamics approach: The self-propelled motion of microscopic bodies immersed in a fluid medium is\nstudied using molecular dynamics simulation. The advantage of the atomistic\napproach is that the detailed level of description allows complete freedom in\nspecifying the swimmer design and its coupling with the surrounding fluid. A\nseries of two-dimensional swimming bodies employing a variety of propulsion\nmechanisms -- motivated by biological and microrobotic designs -- is\ninvestigated, including the use of moving limbs, changing body shapes and fluid\njets. The swimming efficiency and the nature of the induced, time-dependent\nflow fields are found to differ widely among body designs and propulsion\nmechanisms."
    },
    {
        "anchor": "Orientation-dependent propulsion of cone-shaped nano- and microparticles\n  by a traveling ultrasound wave: Previous studies on ultrasound-propelled nano- and microparticles have\nconsidered only systems where the particle orientation is perpendicular to the\ndirection of propagation of the ultrasound. However, in future applications of\nthese particles, they will typically be able to attain also other orientations.\nTherefore, using direct acoustofluidic simulations, we here study how the\npropulsion of cone-shaped nano- and microparticles, which are known to have a\nparticularly efficient acoustic propulsion and are therefore promising\ncandidates for future applications, depends on their orientation relative to\nthe propagation direction of a traveling ultrasound wave. Our results reveal\nthat the propulsion of the particles depends strongly on their orientation\nrelative to the direction of wave propagation and that the particles tend to\norient perpendicularly to the wave direction. We also present the\norientation-averaged translational and angular velocities of the particles,\nwhich correspond to the particles' effective propulsion for an isotropic\nexposure to ultrasound. Our results allow assessing how free\nultrasound-propelled colloidal particles move in three spatial dimensions and\nthus constitute an important step towards the realization of the envisaged\nfuture applications of such particles.",
        "positive": "pyMBE: the Python-based Molecule Builder for ESPResSo: We present the Python-based Molecule Builder for ESPResSo (pyMBE), an open\nsource software designed to build coarse-grained models of polyelectrolytes,\npeptides and globular proteins of arbitrary topology into the Extensible\nSimulation Package for Research on Soft Matter (ESPResSo). ESPResSo features\nthe constant pH (cpH) and grand-reaction (G-RxMC) methods, which are powerful\ntools to study macromolecular systems with many reactive groups, permitting to\nefficiently sample systems with multiple coupled chemical equilibria. However,\nsetting up these methods for macromolecules with many different reactive groups\nis a non-trivial and error-prone task, especially for beginners. pyMBE enables\nthe automatic setup of cpH and G-RxMC simulations in ESPResSo, lowering the\nbarrier for newcomers and opening the door to investigate complex systems not\nyet studied with these methods. To demonstrate some of the applications of\npyMBE, we showcase several study cases where pyMBE successfully reproduces\nprevious simulations in the literature done with ESPResSo and other software,\nincluding various simulations of different peptides in bulk solution,\nsimulations of weak polyelectrolytes in dialysis and simulations of globular\nproteins in bulk solution. pyMBE is publicly available as a GitLab repository\n(https://gitlab.com/blancoapa/pyMBE) which includes its source code and various\nsample and test scripts, including the ones that we used to generated the data\npresented in this article."
    },
    {
        "anchor": "Crystallization and order-disorder transition of colloidal particles in\n  a drying suspension: a phase field crystal approach: Using a phase field crystal model we study the structure and dynamics of a\ndrop of colloidal suspension during evaporation of the solvent. We model an\nexperimental system where contact line pinning of the drop on the substrate is\nnon-existent. Under such carefully controlled conditions, evaporation of the\ndrop produces an ordered or disordered arrangement of the colloidal residue\ndepending on the initial average density of solute and the drying rate. We\nobtain a non-equilibrium phase boundary showing amorphous and crystalline\nphases of single component and binary mixtures of colloidal particles in the\ndensity- drying rate plane. While single component colloids order in the two\ndimensional triangular lattice, a symmetric binary mixture of mutually\nrepulsive particles orders in a three sub-lattice order where two of the\nsub-lattices of the triangular lattice are occupied by the two species of\nparticles with the third sub-lattice vacant.",
        "positive": "Nematic topological defects in the presence of axisymmetric fluid flow: Recent numerical simulations of lid-driven cavity flow of a nematic liquid\ncrystal have found dynamical behavior where topological defects rotate about\nthe center of the fluid vortex induced by the lid motion. By considering a\nsimpler geometry of an infinite system with axisymmetric fluid flow we show\nthat the Ericksen-Leslie nematodynamic equation for the director can be solved\nexactly. The solution demonstrates that any configuration of defects will be\nadvected by the fluid flow, with the defects rotating about the center of the\nfluid vortex with the angular velocity of the fluid."
    },
    {
        "anchor": "Phase field models of active matter: We present an overview of phase field modeling of active matter systems as a\ntool for capturing various aspects of complex and active interfaces. We first\ndescribe how interfaces between different phases are characterized in phase\nfield models and provide simple fundamental governing equations that describe\ntheir evolution. For a simple model, we then show how physical properties of\nthe interface, such as surface tension and interface thickness, can be\nrecovered from these equations. We then explain how the phase field formulation\ncan be coupled to various active matter realizations and discuss three\nparticular examples of continuum biphasic active matter: active\nnematic-isotropic interfaces, active matter in viscoelastic environments, and\nactive shells in fluid background. Finally, we describe how multiple phase\nfields can be used to model active cellular monolayers and present a general\nframework that can be applied to the study of tissue behaviour and collective\nmigration.",
        "positive": "Imaging the structure of the domain wall between symmetries\n  interconnected by a discontinuous transition: We have been able to observe with single particle resolution the interface\nbetween two structural symmetries that cannot be interconnected by a continuous\ntransition. By means of an engineered 2D potential that pins the extremity of\nvortex strings an square symmetry was imposed at the surface of a 3D vortex\nsolid. Using the Bitter decoration technique and on account of the continuous\nvortex symmetry we visualize how the induced structure transforms along the\nvortex direction before changing into the expected hexagonal structure at a\nfinite distance from the surface."
    },
    {
        "anchor": "Spontaneous development of 3-D structure in sheared granular flows: Computer simulations of sheared granular fluids, modeled as inelastic hard\nspheres, are presented which show signs of a uniquely three-dimensional\ninstabilty. In the stable regime, a linear velocity profile, $v_{x}=ay$, with\nshear rate $a$ is established using Lees-Edwards boundary conditions. In the\nunstable regime, the velocity profile aquires a dependence on the third\ndimension of the form $v_{x}=ay+sin(2\\pi z/L)$ in a cubic box with sides of\nlength $L$. An analysis of the linearized Navier-Stokes equations shows the\npresence of an instability and gives a simple expression for the critical\nwavevector which is quantitatively consistent with the results of simulations\nand which indicates that the instability persists at low densities.",
        "positive": "Wrinkles, folds and ripplocations: unusual deformation structures of\n  confined elastic sheets at non-zero temperatures: We study the deformation of a fluctuating crystalline sheet confined between\ntwo flat rigid walls as a simple model for layered solids where bonds among\natoms {\\it within} the same layer are much stronger than those {\\it between}\nlayers. When subjected to sufficiently high loads in an appropriate geometry,\nthese solids deform and fail in unconventional ways. Recent experiments suggest\nthat configurations named {\\it ripplocations}, where a layer folds backwards\nover itself, are involved. These structures are distinct and separated by large\nfree energy barriers from smooth {\\it ripples} of the atomic layers that are\nalways present at any non-zero temperature. We use Monte Carlo simulation in\ncombination with an umbrella sampling technique to obtain conditions under\nwhich such structures form and study their specific experimental signatures."
    },
    {
        "anchor": "Activity-induced microswimmer interactions and cooperation in\n  one-dimensional environments: Cooperative motion in biological microswimmers is crucial for their survival\nas it facilitates adhesion to surfaces, formation of hierarchical colonies,\nefficient motion, and enhanced access to nutrients. Synthetic microswimmers\ncurrently lack truly cooperative behavior that originates from activity-induced\ninteractions. Here, we demonstrate that catalytic microswimmers show a variety\nof cooperative behaviors along one-dimensional paths. We show that their speed\nincreases with the number of swimmers, while the activity induces a preferred\ndistance between swimmers. Using a minimal model, we ascribe this behavior to\nan effective activity-induced potential that stems from a competition between\nchemical and hydrodynamic coupling. These interactions further induce active\nself-assembly into trains as well as compact chains that can elongate,\nbreak-up, become immobilized and remobilized. We identify the crucial role that\nenvironment morphology and swimmer directionality play on these highly dynamic\nchain behaviors. These activity-induced interactions open the door towards\nexploiting cooperation for increasing the efficiency of, as well as provide\ntemporal and spatial control over, microswimmer motion, thereby enabling them\nto perform intricate tasks inside complex environments.",
        "positive": "Model for the shear viscosity of suspensions of star polymers and other\n  soft particles: We propose a model to describe the concentration dependence of the viscosity\nof soft particles. We incorporate in a very simple way the softness of the\nparticles into expressions originally developed for rigid spheres. This is done\nby introducing a concentration-dependent critical packing, which is the packing\nat which the suspension looses fluidity. The resultant expression reproduces\nwith high accuracy the experimental results for suspensions of star polymers in\ngood solvents. The model allows to explain a weak increase of the viscosity\nobserved in the case of diblock copolymer stars suggesting that the reason for\nthis peculiar behavior is mainly a consequence of the softness of the\nparticles. In the semi-dilute regime, suspensions of star polymers are modeled\nusing the Daoud-Cotton picture to complete the description in the whole\nconcentration regime."
    },
    {
        "anchor": "Potential of Mean Force between a Spherical Particle Suspended in a\n  Nematic Liquid Crystal and a Substrate: We consider a system where a spherical particle is suspended in a nematic\nliquid crystal confined between two walls. We calculate the liquid-crystal\nmediated potential of mean force between the sphere and a substrate by means of\nMonte Carlo simulations. Three methods are used: a traditional Monte Carlo\napproach, umbrella sampling, and a novel technique that combines canonical\nexpanded ensemble simulations with a recently proposed density of states\nformalism. The latter method offers clear advantages in that it ensures good\nsampling of phase space without prior knowledge of the energy landscape of the\nsystem. The resulting potential of mean force, computed as a function of the\nnormal distance between the sphere and a surface, suggests that the sphere is\nattracted to the surface, even in the absence of attractive molecular\ninteractions.",
        "positive": "Generation of Motion of Drops with Interfacial Contact: A liquid drop moves on a solid surface if it is subjected to a gradient of\nwettability or temperature. However, the pinning defects on the surface\nmanifested in terms of a wetting hysteresis, or first-order nonlinear friction,\nlimit the motion in the sense that a critical size has to be exceeded for a\ndrop to move. The effect of hysteresis can, however, be mitigated by an\nexternal vibration that can be either structured or stochastic, thereby\ncreating a directed motion of the drop. Many of the well-known features of\nrectification, amplification, and switching that are generic to electronics can\nbe engineered with such types of movements. A specific case of interest is the\nrandom coalescence of drops on a surface that gives rise to self-generated\nnoise. This noise overcomes the pinning potential, thereby generating a random\nmotion of the coalesced drops. Randomly moving coalesced drops themselves\nexhibit a directed diffusive flux when a boundary is present to eliminate them\nby absorption. With the presence of a bias, the coalesced drops execute a\ndiffusive drift motion that can have useful applications in various water and\nthermal management technologies."
    },
    {
        "anchor": "Recent advances in stimuli-responsive core-shell microgel particles:\n  synthesis, characterisation, and applications: Inspired by the path followed by Matthias Ballauff over the past 20 years,\nthe development of thermosensitive core-shell microgel structures is reviewed.\nDifferent chemical approaches, from hard nanoparticle cores to double\nstimuli-responsive microgels have been devised and successfully implemented by\nmany different groups. Some of the rich variety of these systems is presented,\nas well as some recent progress in structural analysis of such microstructures\nby small-angle scattering of neutrons or X-rays, including modeling approaches.\nIn the last part, again following early work by the group of Matthias Ballauff,\napplications with particular emphasis on incorporation of catalytic\nnanoparticles inside core-shell structures -- stabilizing the nanoparticles and\ngranting external control over activity -- will be discussed, as well as\ncore-shell microgels at interfaces.",
        "positive": "Machine Eye for Defects: Machine Learning-Based Solution to Identify and\n  Characterize Topological Defects in Textured Images of Nematic Materials: Topological defects play a key role in the structures and dynamics of liquid\ncrystals (LCs) and other ordered systems. There is a recent interest in\nstudying defects in different biological systems with distinct textures.\nHowever, a robust method to directly recognize defects and extract their\nstructural features from various traditional and nontraditional nematic systems\nremains challenging to date. Here we present a machine learning solution,\ntermed Machine Eye for Defects (MED), for automated defect analysis in images\nwith diverse nematic textures. MED seamlessly integrates state-of-the-art\nobject detection networks, Segment Anything Model, and vision transformer\nalgorithms with tailored computer vision techniques. We show that MED can\naccurately identify the positions, winding numbers, and orientations of $\\pm\n1/2$ defects across distinct cellular contours, sparse vector fields of nematic\ndirectors, actin filaments, microtubules, and simulation images of Gay--Berne\nparticles. MED performs faster than conventional defect detection method and\ncan achieve over 90\\% accuracy on recognizing $\\pm1/2$ defects and their\norientations from vector fields and experimental tissue images. We further\ndemonstrate that MED can identify defect types that are not included in the\ntraining data, such as giant-core defects and defects with higher winding\nnumber. Remarkably, MED provides correct structural information about $\\pm 1$\ndefects, i.e., the phase angle for $+1$ defects and the orientation angle for\n$-1$ defects. As such, MED stands poised to transform studies of diverse\nordered systems by providing automated, rapid, accurate, and insightful defect\nanalysis."
    },
    {
        "anchor": "Sliding across a surface: particles with fixed and mobile ligands: A quantitative model of the mobility of functionalized particles at the\ninterface is pivotal to understanding important systems in biology and\nnanotechnology. In this work, we investigate the emerging dynamics of particles\nanchored through ligand-receptor bridges to functionalized surfaces. We\nconsider systems with reversible bridges in which ligand-receptor pairs\nbind/unbind with finite reaction rates. For a given set of bridges, the\nparticle can explore a tiny fraction of the surface as the extensivity of the\nbridges is finite. We show how at time scales longer than the bridges'\nlifetime, the averaged position of the particle diffuses away from its initial\nvalue. We distill our findings into two analytic equations for the sliding\ndiffusion constant of particles carrying mobile and fixed ligands. We\nquantitatively validate our theoretical predictions using reaction-diffusion\nsimulations. Our results, along with recent literature, will allow inferring\nthe microscopic parameters at play in complex biological systems from\nexperimental trajectories.",
        "positive": "Permeability of porous foamy materials: In this paper, we study the effects of both the amount of open cell walls and\ntheir aperture sizes on solid foams permeability. FEM flow simulations are\nperformed at both pore and macroscopic scales. For foams with fully\ninterconnected pores, we obtain a robust power-law relationship between\npermeability and membrane aperture size. This result owns to the local pressure\ndrop mechanism through the membrane aperture as described by Sampson for fluid\nflow through a circular orifice in a thin plate. Based on this local law,\npore-network simulation of simple flow is used and is shown to reproduce\nsuccessfully FEM results. This low computational cost method allowed to study\nin detail the effects of the open wall amount on percolation, percolating\nporosity and permeability. A model of effective permeability is proposed and\nshows ability to reproduce the results of network simulations. Finally, an\nexperimental validation of the theoretical model on well controlled solid foam\nis presented."
    },
    {
        "anchor": "Electric-field-driven polymer entry into asymmetric nanoscale channels: The electric-field-driven entry process of flexible charged polymers such as\nsingle stranded DNA (ssDNA) into asymmetric nanoscale channels such as\nalpha-hemolysin protein channel is studied theoretically and using molecular\ndynamics simulations. Dependence of the height of the free-energy barrier on\nthe polymer length, the strength of the applied electric field and the channel\nentrance geometry is investigated. It is shown that the squeezing effect of the\ndriving field on the polymer and the lateral confinement of the polymer before\nits entry to the channel crucially affect the barrier height and its dependence\non the system parameters. The attempt frequency of the polymer for passing the\nchannel is also discussed. Our theoretical and simulation results support each\nother and describe related data sets of polymer translocation experiments\nthrough the alpha-hemolysin protein channel reasonably well.",
        "positive": "Polymer-based composites for engineering organic memristive devices: Memristive materials are related to neuromorphic applications as they can\ncombine information processing with memory storage in a single computational\nelement, just as biological neurons. Many of these bioinspired materials\nemulate the characteristics of memory and learning processes that happen in the\nbrain. In this work, we report the memristive properties of a two-terminal\n(2-T) organic device based on ionic migration mediated by an ion-transport\npolymer. The material possesses unique memristive properties: it is reversibly\nswitchable, shows tens of conductive states, presents Hebbian learning\ndemonstrated by spiking time dependent plasticity (STDP), and behaves with both\nshort- (STM) and long-term memory (LTM) in a single device. The origin and\nsynergy of both learning phenomena were theoretically explained by means of the\nchemical interaction between ionic electrolytes and the ion-conductive\nmediator. Further discussion on the transport mechanism was included to explain\nthe dynamic behaviour of these ionic devices under a variable electric field.\nWe propose this polymer-based composite as an outstanding neuromorphic material\nfor being tunable, cheap, flexible, easy to process, reproducible, and more\nbiocompatible than their inorganic analogues."
    },
    {
        "anchor": "Sustained Order-Disorder Transitions in a Model Colloidal System Driven\n  by Rhythmic Crosslinking: Biological systems have the unique ability to self-organize and generate\nautonomous motion and work. Motivated by this, we investigate a 2D model\ncolloidal network that can repeatedly transition between disordered states of\nlow connectivity and ordered states of high connectivity via rhythmic binding\nand unbinding of biomimetic crosslinkers. We use Langevin dynamics to\ninvestigate the time-dependent changes in structure and collective properties\nof this system as a function of colloidal packing fractions and crosslinker\noscillation periods and characterize the degree of order in the system by using\nnetwork connectivity, bond length distributions, and collective motion. Our\nsimulations suggest that we can achieve distinct states of this colloidal\nsystem with pronounced differences in microstructural order and large residence\ntimes in the ordered state when crosslinker kinetics and lifetimes depend\ndirectly on the oscillation period and this oscillation period is much larger\nthan the colloidal diffusion time. Our results will provide insights into the\nrational design of smart active materials that can independently cycle between\nordered and disordered states with desired material properties on a programmed\nschedule.",
        "positive": "Numerical study on a disordered model for DNA denaturation transition: We study numerically a disordered version of the model for DNA denaturation\ntransition (DSAW-DNA) consisting of two interacting SAWs in 3d, which undergoes\na first order transition in the homogeneous case. The two possible values eAT\nand eGC of the interactions between base pairs are taken as quenched random\nvariables distributed with equal probability along the chain. We measure\nquantities averaged over disorder such as the energy density, the specific heat\nand the probability distribution of the loop lengths. When applying the scaling\nlaws used in the homogeneous case we find that the transition seems to be\nsmoother in presence of disorder, in agreement with general theoretical\narguments. Nevertheless we can not rule out the possibility of a still first\norder transition."
    },
    {
        "anchor": "Boosting micromachine studies with Stokesian Dynamics: Artificial microswimmers, nano and microrobots, are essential in many\napplications from engineering to biology and medicine. We present a Stokesian\nDynamics study of the dynamical properties and efficiency of one of the\nsimplest artificial swimmer, the three linked spheres swimmer (TLS),\nextensively shown to be an excellent and model example of a deformable\nmicromachine. Results for two different swimming strokes are compared with an\napproximate solution based on point force interactions. While this\napproximation accurately reproduces the solutions for swimmers with long arms\nand strokes of small amplitude, it fails when the amplitude of the stroke is\nsuch that the spheres come close together, a condition where indeed the largest\nefficiencies are obtained. We find that swimmers with a \"square stroke cycle\"\nresult more efficient than those with \"circular stroke cycle\" when the swimmer\narms are long compared with the sphere radius, but the differences between the\ntwo strokes are smaller when the arms of the swimmers are short. This extended\ntheoretical research of TLS incorporates a much precise description of the\nswimmer hydrodynamics, demonstrating the relevance of considering the finite\nsize of the constitutive microswimmers spheres. This work expects to trigger\nfuture innovative steps contributing to the design of micro and nanomachines\nand its applications.",
        "positive": "Increased intermolecular interactions and cluster formation at the onset\n  of the twist-bend nematic phase in thioether cyanobiphenyl-based liquid\n  crystal dimers: Infrared spectroscopy (IR) and quantum chemistry calculations, based on\ndensity functional theory (DFT) were used to study the structure and the\nmolecular interactions in the nematic (N) and twist-bend (NTB) phases of\nthioether-linked dimers. Infrared absorbance measurements were conducted in a\npolarized beam for homogeneously aligned samples to measure and understand the\norientation of the vibrational transition dipole moments in the liquid crystal\nstates. Revealing temperature-dependent changes in the mean IR absorbance in\nthe twist-bend nematic phase were observed. In the transition from the N to the\nNTB phase, is was found to be associated with a decrease in absorbance for the\nlongitudinal dipoles. This is a result of the antiparallel axial interactions\nof the dipoles, while the absorbance of the transverse dipoles remained\nunchanged up to 340 K and then increased and the dipoles correlated in\nparallel. In order to account for the molecular arrangement in the nematic\nphase, DFT calculations were conducted for the system nearest to the lateral\nneighborhoods. Changes in the square of transition dipoles were found to be\nquite similar to the mean absorbance that was observed in the IR spectra.\nInteractions of molecules that were dominated by pair formation was observed as\nwell as a shift of the long axes of the molecules relative to each other. The\nmost important observation from the spectroscopic measurements was the sudden\nincrease in the intermolecular interactions as the temperature decreased from\nthe N to the NTB phase. This was evidenced by a significant increase in the\ncorrelation of the dipoles that were induced in the dimer cores."
    },
    {
        "anchor": "The constitutive behaviour of strong cohesive particulate gels in\n  compression: A simple and popular constitutive model used to describe the compressional\nstrength of a consolidating strongly cohesive particulate gel is tested further\nwith new experimental data. Strong cohesive particulate gels have variously\nbeen described as being ratchet (poro) elastic, on the one hand, and as having\na yield stress in compression, on the other, to the point where same groups of\nworkers have used both descriptions at one time or another. The dichotomy is\nreal though as such gels do show a hitherto somewhat puzzling elastic-plastic\nduality. This can be explained in part by the strong concentration dependence\nof the modulus since this leads to irreversible volumetric strain-hardening, in\neffect, the ratchet; but only in small part. The real problem seems to be that,\nuntil very recently, most work on consolidation has neglected what what\nMichaels and Bolger told us to do over 50 years ago, viz. to take into wall\nadhesion into account, most cohesive particulate gels being adhesive too. Since\nwall adhesive failure is plastic in character, the simplest non-linear elastic\nmodel of compressive strength can be combined with the simplest possible model\nof wall debonding to produce a approximate complete constitutive description.\nExamples of the use of such a description in detailed modelling of\nconsolidation equilibrium can be found in refs 10-12. Consolidation dynamics\nwith wall adhesion is a substantial modelling challenge remaining to be\ntackled.",
        "positive": "On a discussion about the determination of surface characteristics of\n  microemulsion droplets from static and dynamic scattering experiments: The interpretation of static and dynamic scattering experiments on droplet\nmicroemulsions is discussed. We review the arguments given in our previous\npapers that call into question the methods of current determination of basic\nphenomenological characteristics of the droplet surfactant monolayer, such as\nthe bending and Gaussian rigidities. We give also responses to our criticism by\nT. Hellweg, B. Farago, M. Gradzielski, D. Langevin, and S. Safran (Colloids and\nSurfaces A 221 (2003) 257 and some other works by these authors). They agree\nwith some of our objections; the rest of their response is shown to be flawed.\nWe also show that in many points their way of discussion is improper and\nmisleading. It is concluded that the values of the parameters of microemulsion\ndroplets, as extracted in their experiments, are not reliable and should be\nreexamined."
    },
    {
        "anchor": "Slip-Mediated Dewetting of Polymer Microdroplets: Classical hydrodynamic models predict that infinite work is required to move\na three-phase contact line, defined here as the line where a liquid/vapor\ninterface intersects a solid surface. Assuming a slip boundary condition, in\nwhich the liquid slides against the solid, such an unphysical prediction is\navoided. In this article, we present the results of experiments in which a\ncontact line moves and where slip is a dominating and controllable factor.\nSpherical cap shaped polystyrene microdroplets, with non-equilibrium contact\nangle, are placed on solid self-assembled monolayer coatings from which they\ndewet. The relaxation is monitored using \\textit{in situ} atomic force\nmicroscopy. We find that slip has a strong influence on the droplet evolutions,\nboth on the transient non-spherical shapes and contact line dynamics. The\nobservations are in agreement with scaling analysis and boundary element\nnumerical integration of the governing Stokes equations, including a Navier\nslip boundary condition.",
        "positive": "Active ploughing through a compressible viscoelastic fluid: Unjamming\n  and emergent nonreciprocity: A dilute suspension of active Brownian particles in a dense compressible\nviscoelastic fluid, forms a natural setting to study the emergence of\nnonreciprocity during a dynamical phase transition. At these densities, the\ntransport of active particles is strongly influenced by the passive medium and\nshows a dynamical jamming transition as a function of activity and medium\ndensity. In the process, the compressible medium is actively churned up -for\nlow activity, the active particle gets self-trapped in a spherical cavity of\nits own making, while for large activity, the active particle ploughs through\nthe medium, either accompanied by a moving anisotropic wake, or leaving a\nporous trail. A hydrodynamic approach makes it evident that the active particle\ngenerates a long range density wake which breaks fore-aft symmetry, consistent\nwith the simulations. Accounting for the back reaction of the compressible\nmedium leads to (i) dynamical jamming of the active particle, and (ii) a\ndynamical non-reciprocal attraction between two active particles moving along\nthe same direction, with the trailing particle catching up with the leading one\nin finite time. We emphasize that these nonreciprocal effects appear only when\nthe active particles are moving and so manifest in the vicinity of the\njamming-unjamming transition."
    },
    {
        "anchor": "Fundamental structural characteristics of planar granular assemblies:\n  self-organisation and scaling away friction and initial state: We identify the fundamental factors determining the microstructural (MS)\nstatistics of granular systems, using numerical experiments on 2D assemblies of\npolydisperse frictional discs and studying the emergent properties of quadrons\n(Qs), the basic structural elements of granular solids, whose statistics are\nuniversal-like[1]. The dependence of the structures and of the packing fraction\non friction and initial state are analysed and we report the following. 1.\nDerivation of an analytical formula for the mean Q volume in terms of: the mean\ncoordination number, the packing fraction and the rattlers fraction. 2.\nDerivation of a unique, initial-state-independent, relation between the mean\ncoordination number and the rattler-free packing fraction. We support the\nrelation with data for a range of different systems. 3. Collapse of the Q\nvolume distributions of all systems onto one curve, having an exponential tail.\n4. Decomposition of the Q volumes distribution into conditional distributions,\neach of these also collapsing onto a single curve. 5. The mean Q volume\ndecreases with increasing inter-granular friction coefficients, an effect\nprominent in high order cells. We argue that this phenomenon is due to an\nincreased probability of stable irregularly-shaped cells and test this by a\nherewith developed free cell analytical model. We conclude that, in principle,\nthe MS characteristics are governed mainly by the packing procedure, while\neffects of friction and initial states can be scaled away. Yet, mechanical\nconstraints limit slightly occurrence of small Q volumes in large cells, which\ndoes depend on friction. We quantify this deviation from exact collapse for\nthese cells. 6. We argue that our results support the view that ensemble\ngranular statistical mechanics does not satisfy the uniform measure assumption\nof conventional statistical mechanics.",
        "positive": "Machine Learning Characterization of Structural Defects in Amorphous\n  Packings of Dimers and Ellipses: Structural defects within amorphous packings of symmetric particles can be\ncharacterized using a machine learning approach that incorporates structure\nfunctions of radial distances and angular arrangement. This yields a scalar\nfield, \\emph{softness}, that correlates with the probability that a particle is\nabout to rearrange. However, when particle shapes are elongated, as in the case\nof dimers and ellipses, we find the standard structure functions produce\nimprecise softness measurements. Moreover, ellipses exhibit deformation\nprofiles in stark contrast to circular particles. In order to account for\neffects of orientation and alignment, we introduce new structure functions to\nrecover predictive performance of softness, as well as provide physical insight\nto local and extended dynamics. We study a model disordered solid, a bidisperse\ntwo-dimensional granular pillar, driven by uniaxial compression and composed\nentirely of monomers, dimers, or ellipses. We demonstrate how the computation\nof softness via support vector machine extends to dimers and ellipses with the\nintroduction of new orientational structure functions. Then, we highlight the\nspatial extent of rearrangements and defects, as well as their\ncross-correlation, for each particle shape. Finally, we demonstrate how an\nadditional machine learning algorithm, recursive feature elimination, provides\nan avenue to better understand how softness arises from particular structural\naspects. We identify the most crucial structure functions in determining\nsoftness and discuss their physical implications."
    },
    {
        "anchor": "Influence of nano confinement on nematic liquid crystals: We explore the nematic ordering of the rod-like liquid crystals 5CB and 6CB,\nembedded into parallel-aligned nanochannels in mesoporous silicon and silica\nmembranes as a function of mean channel radius (4.7<=R <=8.3 nm), and thus\ngeometrical confinement strength, by optical birefringence measurements in the\ninfrared region. The orientational order inside the nanochannels results in an\nexcess birefringence, which is proportional to the nematic order parameter. It\nevolves continuously upon cooling with a precursor behavior, typical of a\nparanematic state at high temperatures. These observations are compared with\nthe bulk behavior and analyzed within a phenomenological model. Such an\napproach indicates that the strength of the nematic ordering fields sigma is\nbeyond a critical threshold sigma_c =1/2, that separates discontinuous from\ncontinuous paranematic-to-nematic behavior. In agreement with the predictions\nof the phenomenological approach a linear dependency of sigma on the inverse\nchannel radius is found and we can infer therefrom the critical channel radii,\nR_c, separating continuous from discontinuous paranematic-to-isotropic\nbehavior, for 5CB (12.1 nm) and 6CB (14.0 nm). Our analysis suggests that the\ntangential anchoring at the channel walls is of similar strength in mesoporous\nsilicon and mesoporous silica membranes. A comparison with the bulk phase\nbehavior reveals that the nematic order in nanoconfinement is significantly\naffected by channel wall roughness leading to a reduction of the effective\nnematic ordering.",
        "positive": "Optimal Packings of Superballs: Dense hard-particle packings are intimately related to the structure of\nlow-temperature phases of matter and are useful models of heterogeneous\nmaterials and granular media. Most studies of the densest packings in three\ndimensions have considered spherical shapes, and it is only more recently that\nnonspherical shapes (e.g., ellipsoids) have been investigated. Superballs\n(whose shapes are defined by |x1|^2p + |x2|^2p + |x3|^2p <= 1) provide a\nversatile family of convex particles (p >= 0.5) with both cubic- and\noctahedral-like shapes as well as concave particles (0 < p < 0.5) with\noctahedral-like shapes. In this paper, we provide analytical constructions for\nthe densest known superball packings for all convex and concave cases. The\ncandidate maximally dense packings are certain families of Bravais lattice\npackings. The maximal packing density as a function of p is nonanalytic at the\nsphere-point (p = 1) and increases dramatically as p moves away from unity. The\npacking characteristics determined by the broken rotational symmetry of\nsuperballs are similar to but richer than their two-dimensional \"superdisk\"\ncounterparts, and are distinctly different from that of ellipsoid packings. Our\ncandidate optimal superball packings provide a starting point to quantify the\nequilibrium phase behavior of superball systems, which should deepen our\nunderstanding of the statistical thermodynamics of nonspherical-particle\nsystems."
    },
    {
        "anchor": "Relaxation of a Simulated Lipid Bilayer Vesicle Compressed by an AFM: Using Coarse-Grained Molecular Dynamics simulations, we study the relaxation\nof bilayer vesicles, uniaxially compressed by an Atomic Force Microscope (AFM)\ncantilever. The relaxation time exhibits a strong force-dependence.\nForce-compression curves are very similar to recent experiments wherein giant\nunilamellar vesicles were compressed in a nearly identical manner.",
        "positive": "Extended Micromorphic Computational Homogenization for Mechanical\n  Metamaterials Exhibiting Multiple Geometric Pattern Transformations: Honeycomb-like microstructures have been shown to exhibit local elastic\nbuckling under compression, with three possible geometric buckling modes, or\npattern transformations. The individual pattern transformations, and\nconsequently also spatially distributed patterns, can be induced by controlling\nthe applied compression along two orthogonal directions. Exploitation of this\nproperty holds great potential in, e.g., soft robotics applications. For fast\nand optimal design, efficient numerical tools are required, capable of bridging\nthe gap between the microstructural and engineering scale, while capturing all\nrelevant pattern transformations. A micromorphic homogenization framework for\nmaterials exhibiting multiple pattern transformations is therefore presented in\nthis paper, which extends the micromorphic scheme of Roko\\v{s} et al., J. Mech.\nPhys. Solids 123, 119-137 (2019), for elastomeric metamaterials exhibiting only\na single pattern transformation. The methodology is based on a suitable\nkinematic ansatz consisting of a smooth part, a set of spatially correlated\nfluctuating fields, and a remaining, spatially uncorrelated microfluctuation\nfield. Whereas the latter field is neglected or condensed out at the level of\neach macroscopic material point, the magnitudes of the spatially correlated\nfluctuating fields emerge at the macroscale as micromorphic fields. We develop\nthe balance equations which these micromorphic fields must satisfy as well as a\ncomputational homogenization approach to compute the generalized stresses\nfeaturing in these equations. To demonstrate the potential of the methodology,\nloading cases resulting in mixed modes in both space and time are studied and\ncompared against full-scale simulations. It is shown that the proposed\nframework is capable of capturing the relevant phenomena, although the inherent\nmultiplicity of solutions entails sensitivity to the initial guess."
    },
    {
        "anchor": "Overshoots in stress strain curves: Colloid experiments and schematic\n  mode coupling theory: The stress versus strain curves in dense colloidal dispersions under start-up\nshear flow are investigated combining experiments on model core-shell\nmicrogels, computer simulations of hard disk mixtures, and mode coupling\ntheory. In dense fluid and glassy states, the transient stresses exhibit first\na linear increase with the accumulated strain, then a maximum ('stress\novershoot') for strain values around 5%, before finally approaching the\nstationary value, which makes up the flow curve. These phenomena arise in\nwell-equilibrated systems and for homogeneous flows, indicating that they are\ngeneric phenomena of the shear-driven transient structural relaxation.\nMicroscopic mode coupling theory (generalized to flowing states by integration\nthrough the transients) derives them from the transient stress correlations,\nwhich first exhibit a plateau (corresponding to the solid-like elastic shear\nmodulus) at intermediate times, and then negative stress correlations during\nthe final decay. We introduce and validate a schematic model within mode\ncoupling theory which captures all of these phenomena and handily can be used\nto jointly analyse linear and large-amplitude moduli, flow curves, and\nstress-strain curves. This is done by introducing a new strain- and\ntime-dependent vertex into the relation between the the generalized shear\nmodulus and the transient density correlator.",
        "positive": "Entropically driven reentrant SmC-SmA-SmC phase transition in composite\n  polymer--liquid crystal systems: I consider the effects of polymers on the smectic phase of a host liquid\ncrystal matrix. Focusing on the regime in which the polymers are predominately\nconfined between the smectic layers, I find that the presence of the polymers\ncan lead to a reentrant phase diagram with the smectic-C sandwiching the\nsmectic-A phase from both the high and low temperature sides. Simple\nentropy-energy arguments predict the shape of the reentrant phase boundary."
    },
    {
        "anchor": "Binary icosahedral quasicrystals of hard spheres in spherical\n  confinement: The influence of geometry on the local and global packing of particles is\nimportant to many fundamental and applied research themes such as the structure\nand stability of liquids, crystals and glasses. Here, we show by experiments\nand simulations that a binary mixture of hard-sphere-like particles\ncrystallizing into the MgZn2 Laves phase in bulk, spontaneously forms 3D\nicosahedral quasicrystals in slowly drying droplets. Moreover, the local\nsymmetry of 70-80% of the particles changes to that of the MgCu2 Laves phase.\nBoth of these findings are significant for photonic applications. If the\nstoichiometry deviates from that of the Laves phase, our experiments show that\nthe crystallization of MgZn2 is hardly affected by the spherical confinement.\nOur simulations show that the quasicrystals nucleate away from the spherical\nboundary and grow along five-fold symmetric structures. Our findings not only\nopen the way for particle-level studies of nucleation and growth of 3D\nquasicrystals, but also of binary crystallization.",
        "positive": "Contiguous Patches of Translational Hydration Dynamics on the Surface of\n  K-Ras: Proteins involved in signaling pathways represent an interesting target for\nexperimental analysis by ODNP (Overhauser Dynamic Nuclear Polarization), which\ndetermines the translational mobility at the surface of proteins. They also\nrepresent a challenge, since the hydration dynamics at all sites remains\nrelatively rapid, requiring sensitive measurements capable of drawing finer\ndistinctions. Targeting the protein K-Ras, we find ODNP cross-relaxivity values\nthat appear consistent within similar regions of 3D space, regardless of the\nspecific residue where the spin probe used to select the location has been\nattached. The similar dynamics observed from nearby residues indicate a\npersistence/uniformity of the translational dynamics of water on the nanometer\nscale. This results makes sense, since it essentially means that the dynamics\nof water remains consistent over a lengthscale (a nanometer) over which liquid\nwater exhibits structural persistence (i.e. its correlation length). This opens\nup the possibility of strategically and comprehensively mapping out the\nhydration layer in aqueous solution and identifying regions that contribute\nsignificantly to the free energy of binding interactions -- for example, slow\nwater that might contribute significant entropy, or regions with strongly\ntemperature-dependent water mobility that might contribute significant\nenthalpy."
    },
    {
        "anchor": "Size Distribution of Superparamagnetic Particles Determined by Magnetic\n  Sedimentation: We report on the use of magnetic sedimentation as a means to determine the\nsize distribution of dispersed magnetic particles. The particles investigated\nhere are i) single anionic and cationic nanoparticles of diameter D = 7 nm and\nii) nanoparticle clusters resulting from electrostatic complexation with\npolyelectrolytes and polyelectrolyte-neutral copolymers. A theoretical\nexpression of the sedimentation concentration profiles at the steady state is\nproposed and it is found to describe accurately the experimental data. When\ncompared to dynamic light scattering, vibrating sample magnetometry and\ncryogenic transmission electron microscopy, magnetic sedimentation exhibits a\nunique property : it provides the core size and core size distribution of\nnanoparticle aggregates.",
        "positive": "Structure and scaling laws of liquid/vapor interfaces close to the\n  critical point: To reach a deeper understanding of fluid interfaces it is necessary to\nidentify a meaningful coarse-graining length that separates intrinsic\nfluctuations from capillary ones, given the lack of a proper statistical\nmechanical definition of the latter. Here, with the help of unsupervised\nlearning techniques, we introduce a new length scale based on the local density\nof the fluid. This length scale follows a scaling law that diverges more mildly\nthan the bulk correlation length upon approaching the critical point. This\nallows to distinguish regimes of correlated and uncorrelated capillary waves\nfrom that of intrinsic fluctuations."
    },
    {
        "anchor": "Effect of geometry on the dewetting of granular chains by evaporation: Understanding evaporation or drying in granular media still remains complex\ndespite recent advancements. Evaporation depends on liquid transport across a\nconnected film network from the bulk to the surface. In this study, we\ninvestigate the stability of film networks as a function of granular packing.\nUsing a controlled experimental approach, we vary the granular packing geometry\nand show the changes in the height of the liquid film network during\nevaporation as packing shifts from a loose-packed to a close-packed\narrangement. This height can be calculated from an equilibrium between\nhydrostatic pressure and the pressure difference between two points in the\nvertical film network. We use a simulation approach to calculate the pressure\nin both the percolating front and evaporating front within the two-phase zone\nof air/water mixture. Results show good agreement between the model and the\nexperiment.",
        "positive": "Diffusivity and configurational entropy maxima in short range attractive\n  colloids: We study tagged particle diffusion at large packing fractions, for a model of\nparticles interacting with a generalized Lennard-Jones 2n-n potential, with\nlarge n. The resulting short-range potential mimics interactions in colloidal\nsystems. In agreement with previous calculations for short-range potential, we\nobserve a diffusivity maximum as a function of temperature. By studying the\ntemperature dependence of the configurational entropy -- which we evaluate with\ntwo different methods -- we show that a configurational entropy maximum is\nobserved at a temperature close to that of the diffusivity maximum. Our\nfindings suggest a relationbetween dynamics and number of distinct states for\nshort-range potentials."
    },
    {
        "anchor": "J-factors of short DNA molecules: The propensity of short DNA sequences to convert to the circular form is\nstudied by a mesoscopic Hamiltonian method which incorporates both the bending\nof the molecule axis and the intrinsic twist of the DNA strands. The base pair\nfluctuations with respect to the helix diameter are treated as path\ntrajectories in the imaginary time path integral formalism. The partition\nfunction for the sub-ensemble of closed molecules is computed by imposing chain\nends boundary conditions both on the radial fluctuations and on the angular\ndegrees of freedom. The cyclization probability, the J-factor, proves to be\nhighly sensitive to the stacking potential, mostly to its nonlinear parameters.\nWe find that the J-factor generally decreases by reducing the sequence length (\nN ) and, more significantly, below N = 100 base pairs. However, even for very\nsmall molecules, the J-factors remain sizeable in line with recent experimental\nindications. Large bending angles between adjacent base pairs and anharmonic\nstacking appear as the causes of the helix flexibility at short length scales.",
        "positive": "The Collective Snapping of a Pair of Bumping Buckled Beams: When a pair of parallel buckling beams of unequal width make lateral contact\nunder increasing compression, eventually either the thin or the thick beam will\nsnap, leading to collective motion of the beam pair. Using experiments and FEM\nsimulations, we find that the distance $D$ between the beams selects which beam\nsnaps first, and that the critical distance $D^*$ scales linear with the\ncombined width of the two beams. To understand this behavior, we show that the\ncollective motion of the beams is governed by a pitchfork bifurcation that\noccurs at strains just below snapping. Specifically, we use a model of two\ncoupled Bellini trusses to find a closed form expression for the location of\nthis pitchfork bifurcation that captures the linear scaling of $D^*$ with beam\nwidth. Our work uncovers a novel elastic instability that combines buckling,\nsnapping and contact nonlinearities. This instability underlies the packing of\nparallel confined beams, and can be leveraged in advanced metamaterials."
    },
    {
        "anchor": "Randomly cross-linked polymer models: Polymer models are used to describe chromatin, which can be folded at\ndifferent spatial scales by binding molecules. By folding, chromatin generates\nloops of various sizes. We present here a randomly cross-linked (RCL) polymer\nmodel, where monomer pairs are connected randomly. We obtain asymptotic\nformulas for the steady-state variance, encounter probability, the radius of\ngyration, instantaneous displacement and the mean first encounter time between\nany two monomers. The analytical results are confirmed by Brownian simulations.\nFinally, the present results can be used to extract the minimum number of\ncross-links in a chromatin region from {conformation capture} data.",
        "positive": "The effect of topology on the structure and free energy landscape of DNA\n  kissing complexes: We use a recently developed coarse-grained model for DNA to study kissing\ncomplexes formed by hybridization of complementary hairpin loops. The binding\nof the loops is topologically constrained because their linking number must\nremain constant. By studying systems with linking numbers -1, 0 or 1 we show\nthat the average number of interstrand base pairs is larger when the topology\nis more favourable for the right-handed wrapping of strands around each other.\nThe thermodynamic stability of the kissing complex also decreases when the\nlinking number changes from -1 to 0 to 1. The structures of the kissing\ncomplexes typically involve two intermolecular helices that coaxially stack\nwith the hairpin stems at a parallel four-way junction."
    },
    {
        "anchor": "Ion assisted structural collapse of a single stranded DNA: a molecular\n  dynamics approach: The structure and dynamics of negatively charged nucleic acids strongly\ncorrelate with the concentration and charge of the oppositely charged\ncounter-ions. It is well known that the structural collapse of DNA is favored\nin the presence of additional salt, a source of excess oppositely charged ions.\nUnder such conditions single stranded DNA adopts a collapsed coil like\nconformation, typically characterized by stacking base pairs. Using atomistic\nmolecular dynamics simulation, we demonstrate that in the presence of\nadditional divalent salt (MgCl2) single stranded DNA (Dickerson Drew dodecamer)\ninitially collapses and then expands with increasing salt concentration. This\nis due to the overcharging induced DNA chain swelling, a dominant factor at a\nhigher divalent salt concentration. In a nutshell, our simulations show how in\nthe presence of divalent salt, non-sequential base stacking and overcharging\ncompetes and affect single stranded DNA dynamics unlike a monovalent salt.",
        "positive": "Stochastic Energetics of Quantum Transport: We examine the stochastic energetics of directed quantum transport due to\nrectification of non-equilibrium thermal fluctuations. We calculate the quantum\nefficiency of a ratchet device both in presence and absence of an external load\nto characterize two quantifiers of efficiency. It has been shown that the\nquantum current as well as efficiency in absence of load (Stokes efficiency) is\nhigher as compared to classical current and efficiency, respectively, at low\ntemperature. The conventional efficiency of the device in presence of load on\nthe other hand is higher for a classical system in contrast to its classical\ncounterpart. The maximum conventional efficiency being independent of the\nnature of the bath and the potential remains the same for classical and quantum\nsystems."
    },
    {
        "anchor": "Scaling behavior of topologically constrained polymer rings in a melt: Large scale molecular dynamics simulations on graphic processing units (GPUs)\nare employed to study the scaling behavior of ring polymers with various\ntopological constraints in melts. Typical sizes of rings containing $3_1$,\n$5_1$ knots and catenanes made up of two unknotted rings scale like $N^{1/3}$\nin the limit of large ring sizes $N$. This is consistent with the crumpled\nglobule model and similar findings for unknotted rings. For small ring lengths\nknots occupy a significant fraction of the ring. The scaling of typical ring\nsizes for small $N$ thus depends on the particular knot type and the exponent\nis generally larger than 0.4.",
        "positive": "Folding in two-dimenensional off-lattice models of proteins: Model off-lattice sequences in two dimensions are constructed so that their\nnative states are close to an on-lattice target. The Hamiltonian involves the\nLennard-Jones and harmonic interactions. The native states of these sequences\nare determined with a high degree of certainty through Monte Carlo processes.\nThe sequences are characterized thermodynamically and kinetically. It is shown\nthat the rank-ordering-based scheme of the assignment of contact energies\ntypically fails in off-lattice models even though it generates high stability\nof on-lattice sequences. Similar to the on-lattice case, Go-like modeling, in\nwhich the interaction potentials are restricted to the native contacts in a\ntarget shape, gives rise to good folding properties. Involving other contacts\ndeteriorates these properties."
    },
    {
        "anchor": "Local Writhing Dynamics: We present an alternative local definition of the writhe of a self-avoiding\nclosed loop which differs from the traditional non-local definition by an\ninteger. When studying dynamics this difference is immaterial. We employ a\nformula due to Aldinger, Klapper and Tabor for the change in writhe and propose\na set of local, link preserving dynamics in an attempt to unravel some puzzles\nabout actin.",
        "positive": "Wrapping of Microparticles by Floppy Lipid Vesicles: Lipid membranes, the barrier defining living cells and many of their\nsub-compartments, bind to a wide variety of nano- and micro-meter sized\nobjects. In the presence of strong adhesive forces, membranes can strongly\ndeform and wrap the particles, an essential step in crossing the membrane for a\nvariety of health and disease-related processes. A large body of theoretical\nand numerical work has focused on identifying the physical properties that\nunderly wrapping. Using a model system of micron-sized colloidal particles and\ngiant unilamellar lipid vesicles with tunable adhesive forces, we measure a\nwrapping phase diagram and make quantitative comparisons to theoretical models.\nOur data is consistent with a model of membrane-particle interactions\naccounting for the adhesive energy per unit area, membrane bending rigidity,\nparticle size, and vesicle radius."
    },
    {
        "anchor": "Molecular model for de Vries type smectic A - smectic C phase transition\n  in liquid crystals: We develop a theory of Smectic A - Smectic C phase transition with\nanomalously weak smectic layer contraction. We construct a phenomenological\ndescription of this transition by generalizing the Chen-Lubensky model. Using a\nmean-field molecular model, we demonstrate that a relatively simple interaction\npotential suffices to describe the transition. The theoretical results are in\nexcellent agreement with experimental data.",
        "positive": "Magnetically induced elastic deformations of magnetic gels and\n  elastomers containing particles of mixed size: Soft elastic composite materials can serve as actuators when they transform\nchanges in external fields into mechanical deformation. Here, we address the\ncorresponding deformational behavior of magnetic gels and elastomers,\nconsisting of magnetizable colloidal particles in a soft polymeric matrix and\nexposed to external magnetic fields. Since many practical realizations of such\nmaterials involve particulate inclusions of polydisperse size distributions, we\nconcentrate on the effect that mixed particle sizes have on the overall\ndeformational response. To perform a systematic study, our focus is on binary\nsize distributions. We systematically vary the fraction of larger particles\nrelative to smaller ones and characterize the resulting magnetostrictive\nbehavior. The consequences for systems of various different spatial particle\narrangements and different degrees of compressibility of the elastic matrix are\nevaluated. In parts, we observe a qualitative change in the overall response\nfor selected systems of mixed particle sizes. Specifically, overall changes in\nvolume and relative elongations or contractions in response to an induced\nmagnetization can be reversed into the opposite types of behavior. Our results\nshould apply to the characteristics of other soft elastic composite materials\nlike electrorheological gels and elastomers when exposed to external electric\nfields as well. Overall, we hope to stimulate the further investigation on the\npurposeful use of mixed particle sizes as a means to design tailored requested\nmaterial behavior."
    },
    {
        "anchor": "Dewetting dynamics of sheared thin polymer films: an experimental study: An experimental investigation is reported on the effect of shear on the\nbursting of molten ultra-thin polymer films embedded in an immiscible matrix.\nBy using an optical microscope coupled with a shearing hotstage, the dewetting\ndynamics, i.e. the growth of dewetting holes is monitored over time at various\nshear rates. It is observed that their circularity is modified by shear and\nthat for all temperatures and thicknesses studied, the growth speed of the\nformed holes rapidly increases with increasing shear rate. A model balancing\ncapillary forces and viscous dissipation while taking into account\nshear-thinning is then proposed and captures the main features of the\nexperimental data, such as the ellipsoid shape of the holes and the faster\ndynamics in the direction parallel to the shear. This research will help to\nunderstand the instabilities occurring during processing of layered polymeric\nstructures, such as multilayer coextrusion.",
        "positive": "Dynamics of self-propelled tracer particles inside a polymer network: Transport of tracer particles through mesh-like environments such as\nbiological hydrogels and polymer matrices is ubiquitous in nature. These\ntracers could be passive, such as colloids or active (self-propelled), such as\nsynthetic nanomotors or bacteria. Computer simulations in principle should be\nextremely useful in exploring the mechanism of active (self-propelled)\ntransport of tracer particles through the mesh-like environments. Therefore, we\nconstruct a polymer network on a diamond lattice and use computer simulations\nto investigate the dynamics of spherical self-propelled particles inside the\nnetwork. Our main objective is to elucidate the effect of the self-propulsion\non the dynamics of the tracer particle as a function of tracer size and\nstiffness of the polymer network. We compute the time-averaged mean-squared\ndisplacement (MSD) and the van-Hove correlations of the tracer. On one hand, in\nthe case of the bigger sticky particle, caging caused by the network particles\nwins over the escape assisted by the self-propulsion. This results\nintermediate-time subdiffusion. On the other hand, smaller tracers or tracers\nwith high self-propulsion velocities can easily escape from the cages and show\nintermediate-time superdiffusion. Stiffer the network, slower the dynamics of\nthe tracer, and the bigger tracers exhibit longer lived intermediate time\nsuperdiffusion, as the persistence time scales as $\\sim \\sigma^3$, where\n$\\sigma$ is the diameter of the tracer. In intermediate time, non-Gaussianity\nis more pronounced for active tracers. In the long time, the dynamics of the\ntracer, if passive or weakly active, becomes Gaussian and diffusive, but\nremains flat for tracers with high self-propulsion, accounting for their\nseemingly unrestricted motion inside the network."
    },
    {
        "anchor": "Band structure, elementary excitations, and stability of a Bose-Einstein\n  condensate in a periodic potential: We investigate the band structure of a Bose-Einstein condensate in a\none-dimensional periodic potential by calculating stationary solutions of the\nGross-Pitaevskii equation which have the form of Bloch waves. We demonstrate\nthat loops (\"swallow tails\") in the band structure occur both at the Brillouin\nzone boundary and at the center of the zone, and they are therefore a generic\nfeature. A physical interpretation of the swallow tails in terms of periodic\nsolitons is given. The linear stability of the solutions is investigated as a\nfunction of the strength of the mean-field interaction, the magnitude of the\nperiodic potential, and the wave vector of the condensate. The regions of\nenergetic and dynamical stability are identified by considering the behavior of\nthe Gross-Pitaevskii energy functional for small deviations of the condensate\nwave function from a stationary state. It is also shown how for long-wavelength\ndisturbances the stability criteria may be obtained within a hydrodynamic\napproach.",
        "positive": "Move set, algorithm, and folding kinetics of Monte Carlo simulations for\n  lattice polymers: The effect of different move sets on the folding kinetics of the Monte Carlo\nsimulations is analysed based on the conformation-network and the\ntemperature-dependent folding kinetics. A new scheme of implementing Metropolis\nalgorithm is given. The new method is shown to satisfy the detailed balance and\nconverge efficiently towards thermal equilibrium. A new quantity, employed from\nthe continuous time Monte Carlo method, is introduced to identify effectively\nthe kinetic traps of foldings."
    },
    {
        "anchor": "Spreading with evaporation and condensation in one-component fluids: We investigate the dynamics of spreading of a small liquid droplet in gas in\na one-component simple fluid, where the temperature is inhomogeneous around\n0.9Tc and latent heat is released or generated at the interface upon\nevaporation or condensation (with Tc being the critical temperature). In the\nscheme of the dynamic van der Waals theory, the hydrodynamic equations\ncontaining the gradient stress are solved in the axisymmetric geometry. We\nassume that the substrate has a finite thickness and its temperature obeys the\nthermal diffusion equation. A precursor film then spreads ahead of the bulk\ndroplet itself in the complete wetting condition. Cooling the substrate\nenhances condensation of gas onto the advancing film, which mostly takes place\nnear the film edge and can be the dominant mechanism of the film growth in a\nlate stage. The generated latent heat produces a temperature peak or a hot spot\nin the gas region near the film edge. On the other hand, heating the substrate\ninduces evaporation all over the interface. For weak heating, a steady-state\ncircular thin film can be formed on the substrate. For stronger heating,\nevaporation dominates over condensation, leading to eventual disappearance of\nthe liquid region.",
        "positive": "Adsorption of MultiLamellar tubes with a temperature tunable diameter at\n  the air-water interface: a process driven by the bulk properties: The behavior at the air/water interface of multilamellar tubes made of the\nethanolamine salt of the 12-hydroxy stearic acid as a function of the\ntemperature has been investigated using Neutron Reflectivity. Those tubes are\nknown to exhibit a temperature tunable diameter in the bulk. We have observed\nmultilamellar tubes adsorbed at the air/water interface by specular neutron\nreflectivity. Interestingly, at the interface, the adsorbed tubes exhibit the\nsame behavior than in the bulk upon heating. There is however a peculiar\nbehavior at around 50\\degree for which the increase of the diameter of the\ntubes at the interface yields an unfolding of those tubes into a multilamellar\nlayer. Upon further heating, the tubes re-fold and their diameter re-decrease\nafter what they melt as observed in the bulk. All structural transitions at the\ninterface are nevertheless shown to be quasi-completely reversible. This\nprovides to the system a high interest for its interfacial properties because\nthe structure at the air/water interface can be tuned easily by the\ntemperature."
    },
    {
        "anchor": "Dynamics of Highly Supercooled Liquids: The diffusivity of tagged particles is demonstrated to be heterogeneous on\ntime scales comparable to or less than the structural relaxation time %taking\nplace at the interparticle distance in a highly supercooled liquid via 3D\nmolecular dynamics simulation. The particle motions in the relatively active\nregions dominantly contribute to the mean square displacement, giving rise to a\ndiffusion constant systematically larger than the Stokes-Einstein value. The\nvan Hove self-correlation function $G_s(r,t)$ is shown to have a large $r$ tail\nwhich can be scaled in terms of $r/t^{1/2}$ for $t \\ls 3 \\tau_\\alpha$, where\n$\\tau_\\alpha \\cong$ the stress relaxation time. Its presence indicates\nheterogeneous diffusion in the active regions. However, the diffusion process\neventually becomes homogeneous on time scales longer than the life time of the\nheterogeneity structure ($\\sim 3 \\tau_{\\alpha}$).",
        "positive": "Sound-propagation gap in fluid mixtures: We discuss the behavior of the extended sound modes of a dense binary\nhard-sphere mixture. In a dense simple hard-sphere fluid the Enskog theory\npredicts a gap in the sound propagation at large wave vectors. In a binary\nmixture the gap is only present for low concentrations of one of the two\nspecies. At intermediate concentrations sound modes are always propagating.\nThis behavior is not affected by the mass difference of the two species, but it\nonly depends on the packing fractions. The gap is absent when the packing\nfractions are comparable and the mixture structurally resembles a metallic\nglass."
    },
    {
        "anchor": "Holographic interferometry study of the dissolution and diffusion of\n  gypsum in water: We have performed holographic interferometry measurements of the dissolution\nof the (010) plane of a cleaved gypsum single crystal in pure water. These\nexperiments have provided the value of the dissolution rate constant k of\ngypsum in water and the value of the interdiffusion coefficient D of its\naqueous species in water. D is 1.0 x 10^-9 m2 s^-1, a value close to the\ntheoretical value generally used in dissolution studies. k is 4 x 10^-5 mol\nm^-2 s^-1. It directly characterizes the microscopic transfer rate at the\nsolid-liquid interface, and is not an averaged value deduced from quantities\nmeasured far from the surface as in macroscopic dissolution experiments. It is\nfound to be two times lower than the value obtained from macroscopic\nexperiments.",
        "positive": "Inhomogeneous steady shear dynamics of a three-body colloidal gel former: We investigate the stationary flow of a colloidal gel under an inhomogeneous\nexternal shear force using adaptive Brownian dynamics simulations. The\ninterparticle forces are derived from the Stillinger-Weber potential, where the\nthree-body term is tuned to enable network formation and gelation in\nequilibrium. When subjected to the shear force field, the system develops\nremarkable modulations in the one-body density profile. Depending on the shear\nmagnitude, particles accumulate either in quiescent regions or in the vicinity\nof maximum net flow, and we deduce this strong non-equilibrium response to be\ncharacteristic of the gel state. Studying the components of the internal force\nparallel and perpendicular to the flow direction reveals that the emerging flow\nand structure of the stationary state are driven by significant viscous and\nstructural superadiabatic forces. Thereby, the magnitude and nature of the\nobserved non-equilibrium phenomena differs from the corresponding behavior of\nsimple fluids. We demonstrate that a simple power functional theory reproduces\naccurately the viscous force profile, giving a rationale of the complex\ndynamical behavior of the system."
    },
    {
        "anchor": "Thermal compaction of disordered and elastin-like polypeptides: a\n  temperature-dependent, sequence-specific coarse-grained simulation model: Elastin-like polypeptides (ELPs) undergo a sharp solubility transition from\nlow temperature solvated phases to coacervates at elevated temperatures, driven\nby the increased strength of hydrophobic interactions at higher temperatures.\nThe transition temperature, or 'cloud point', critically depends on sequence\ncomposition, sequence length, and concentration of the ELPs. In this work, we\npresent a temperature-dependent, implicit solvent, sequence-specific\ncoarse-grained (CG) simulation model that reproduces the transition\ntemperatures as a function of sequence length and guest residue identity of\nvarious experimentally probed ELPs to appreciable accuracy. Our model builds\nupon the self-organized polymer model introduced recently for intrinsically\ndisordered polypeptides (SOP-IDP), and introduces a semi-empirical functional\nform for the temperature-dependence of hydrophobic interactions. In addition to\nthe fine performance for various ELPs, we demonstrate the ability of our model\nto capture the thermal compactions in dominantly hydrophobic intrinsically\ndisordered polypeptides (IDPs), consistent with experimental scattering data.\nWith the high computational efficiency afforded by the CG representation, we\nenvisage that the model will be ideally suited for simulations of large-scale\nstructures such as ELP networks and hydrogels, as well as agglomerates of IDPs.",
        "positive": "Stochastic kinetic theory applied to coarse-grained polymer model: A stochastic field theory approach is applied to a coarse-grained polymer\nmodel that will enable studies of polymer behavior under non-equilibrium\nconditions. This article is focused on the validation of the new model in\ncomparison to explicit Langevin equation simulations under conditions with\nanalytical solutions. The polymers are modeled as Hookean dumbbells in one\ndimension, without including hydrodynamic interactions and polymer-polymer\ninteractions. Stochastic moment equations are derived from the full field\ntheory. The accuracy of the field theory and moment equations are quantified\nusing autocorrelation functions. The full field theory is only accurate for\nlarge number of polymers due to keeping track of rare occurrences of polymers\nwith a large stretch. The moment equations do not have this error because they\ndo not explicitly track these configurations. The accuracy of both methods\ndepends on the spatial degree of discretization. The timescale of decorrelation\nover length scales bigger than the spatial discretization is accurate, while\nthere is an error over the scale of single mesh points."
    },
    {
        "anchor": "The effect of water/carbon interaction strength on interfacial thermal\n  resistance and the surrounding molecular nanolayer of CNT and graphene\n  nanoparticles: Heat transfer at the liquid/solid interface, especially at the nanoscale, has\nenormous importance in nanofluids. This study investigates liquid/solid\ninterfacial thermal resistance and structure of the formed molecular nanolayer\naround a carbon-based nanoparticle. Employing non-equilibrium molecular\ndynamics simulation and thermal relaxation method, the nanofluid systems with\ndifferent nanoparticle diameters and different surface wettability were\ninvestigated. Simulation results show that carbon nanotubes (CNTs) with a\nsmaller diameter attract more value of the base fluid and lead to a reduced\nKapitza resistance. It was found that the thickness of the nanolayer around the\nnanoparticle is independent of the water/carbon interaction strength. Also, the\nvalue of the Kapitza resistance decreases with increasing the interaction\nstrength. Ultimately, a correlation was proposed for the thermal resistance of\nCNT/water and graphene/water nanofluids in terms of wettability intensity of\nnanoparticle surface. The proposed correlation in addition to fitting to\nsimulation results can cover the physical conditions of the system.",
        "positive": "Controlling the dynamics of a bidimensional gel above and below its\n  percolation transition: The morphology and the microscopic internal dynamics of a bidimensional gel\nformed by spontaneous aggregation of gold nanoparticles confined at the water\nsurface are investigated by a suite of techniques, including grazing-incidence\nx-ray photon correlation spectroscopy (GI-XPCS). The range of concentrations\nstudied spans across the percolation transition for the formation of the gel.\nThe dynamical features observed by GI-XPCS are interpreted in view of the\nresults of microscopical imaging; an intrinsic link between the mechanical\nmodulus and internal dynamics is demonstrated for all the concentrations. Our\nwork presents, to the best of our knowledge, the first example of a transition\nfrom stretched to compressed correlation function actively controlled by\nquasistatically varying the relevant thermodynamic variable. Moreover, by\napplying a model proposed time ago by Duri and Cipelletti [A. Duri and L.\nCipelletti, Europhys. Lett. 76, 972 (2006)] we are able to build a novel master\ncurve for the shape parameter, whose scaling factor allows us to quantify a\n'long time displacement length'. This characteristic length is shown to\nconverge, as the concentration is increased, to the 'short time localization\nlength' determined by pseudo Debye-Waller analysis of the initial contrast.\nFinally, the intrinsic dynamics of the system are then compared with that\ninduced by means of a delicate mechanical perturbation applied to the\ninterface."
    },
    {
        "anchor": "Coffee stains, cell receptors, and time crystals: Lessons from the old\n  literature: Perhaps the most important reason to understand the deep history of a field\nis that it is the right thing to do.",
        "positive": "Anomalous Topological Active Matter: Active systems exhibit spontaneous flows induced by self-propulsion of\nmicroscopic constituents and can reach a nonequilibrium steady state without an\nexternal drive. Constructing the analogy between the quantum anomalous Hall\ninsulators and active matter with spontaneous flows, we show that topologically\nprotected sound modes can arise in a steady-state active system in continuum\nspace. We point out that the net vorticity of the steady-state flow, which acts\nas a counterpart of the gauge field in condensed-matter settings, must vanish\nunder realistic conditions for active systems. The quantum anomalous Hall\neffect thus provides design principles for realizing topological metamaterials.\nWe propose and analyze the concrete minimal model and numerically calculate its\nband structure and eigenvectors, demonstrating the emergence of nonzero bulk\ntopological invariants with the corresponding edge sound modes. This new type\nof topological active systems can potentially expand possibilities for their\nexperimental realizations and may have broad applications to practical active\nmetamaterials. Possible realization of non-Hermitian topological phenomena in\nactive systems is also discussed."
    },
    {
        "anchor": "Discontinuous rigidity transition associated with shear jamming in\n  granular simulations: We investigate the rigidity transition associated with shear jamming in\nfrictionless, as well as frictional, disk packings in the quasi-static regime\nand at low shear rates. For frictionless disks, the transition is under\nquasistatic shear is discontinuous, with an instantaneous emergence of a system\nspanning rigid cluster at the jamming transition. For frictional systems, the\ntransition appears continuous for finite shear rates, but becomes sharper for\nlower shear rates. In the quasi-static limit, it is discontinuous as in the\nfrictionless case. Thus, our results show that the rigidity transition\nassociated with shear jamming is discontinuous, as demonstrated in a past for\nisotropic jamming of frictionless particles, and therefore a unifying feature\nof the jamming transition in general.",
        "positive": "Dynamics of shape fluctuations of quasi-spherical vesicles revisited: In this paper, the dynamics of spontaneous shape fluctuations of a single,\ngiant quasi-spherical vesicle formed of a single lipid species is revisited\ntheoretically. A coherent physical theory for the dynamics is developed based\non a number of fundamental principles and considerations and a systematic\nformulation of the theory is also established. From the systematic theoretical\nformulation, an analytical description of the dynamics of shape fluctuations of\nquasi-spherical vesicles is derived. In particular, in developing the theory we\nhave made a new interpretation of some of the phenomenological constants in a\ncanonical continuum description of fluid lipid-bilayer membranes and shown the\nconsequences of this new interpretation in terms of the characteristics of the\ndynamics of vesicle shape fluctuations. Moreover, we have used the systematic\nformulation of our theory as a framework against which we have discussed the\npreviously existing theories and their discrepancies. Finally, we have made a\nsystematic prediction about the system-dependent characteristics of the\nrelaxation dynamics of shape fluctuations of quasi-spherical vesicles with a\nview of experimental studies of the phenomenon and also discussed, based on our\ntheory, a recently published experimental work on the topic."
    },
    {
        "anchor": "Macromolecular crowding in chiral assembly of ellipsoidal nanoparticles: Anisotropic colloidal particles have the ability to self-assemble into\ncholesteric structures. We used molecular dynamics to simulate the\nself-assembly of ellipsoidal particles with the objective to establish a\ngeneral framework to reveal the primary factors driving chiral interactions. To\ncharacterize these interactions, we introduce a characteristic parameter\nfollowing the crowding factor (CF) theory. Our simulations and statistical\nanalysis showed good agreement with the CF theory; at the early stages of the\nassembly process, the ellipsoidal particles go through a critical aggregation\npoint followed by further clustering towards nematic order. Further, we\ndemonstrate that in high CF conditions, small initial clusters may induce a\nchiral twist which subsequently forms a cholesteric structure with no\ndirectional preference in higher organization states.",
        "positive": "Solid-solid transition of the size-polydisperse hard-sphere system: The solid-solid coexistence of a polydisperse hard sphere system is studied\nby using the Monte Carlo simulation. The results show that for large enough\npolydispersity the solid-solid coexistence state is more stable than the\nsingle-phase solid. The two coexisting solids have different composition\ndistributions but the same crystal structure. Moreover, there is evidence that\nthe solid-solid transition terminates in a critical point as in the case of the\nfluid-fluid transition."
    },
    {
        "anchor": "Magnetic properties of clusters of supracolloidal magnetic polymers with\n  central attraction: Supracolloidal magnetic polymers (SMPs) are structures made by crosslinking\nmagnetic particles. In this work, using Langevin dynamics simulations, we study\nthe zero-field magnetic properties of clusters formed in suspensions of SMPs\nwith different topologies -- chains, rings, X and Y -- that interact via\nStockmayer potential. We find that the presence of central attraction,\nresulting in the formation of large compact clusters, leads to a dramatic\ndecrease of the suspension initial susceptibility, independently from SMP\ntopology. However, the largest decrease corresponds to chain-like SMPs with\nstrongly interacting particles. This is due to the higher rotational degrees of\nfreedom of SMPs with such topology, which allows the particles to reorganise\nthemselves inside the clusters in such a way that their magnetic moments form\nenergetically advantageous vortex structures with negligible net magnetic\nmoments.",
        "positive": "Certifying the intrinsic character of a constitutive law for\n  semi-crystalline polymers: a probation test: A study of methodological nature demonstrates the efficiency of a probation\ntest allowing for the intrinsic character of a rheological constitutive law to\nbe assessed. Such a law is considered here for Semi-Crystalline Polymers\nexhibiting necking and for large deformation. In the framework of a\n$(\\dot\\sigma, \\sigma, \\dot\\varepsilon, \\varepsilon)$ behavior's law, tensile\nexperiments conducted at an imposed constant strain rate $\\dot\\varepsilon_0$\nbring true stress responses from which constitutive (material) parameters can\nbe identified from Model-Based Metrology concepts. The same experiment repeated\nat various strain rates gives then access to the dependence of the non-elastic\nparameters on the strain rate. Then the intrinsic law is tested severely by\nconsidering a new set of experiments carried out for constant displacement\nrates of the grips. In that case, the specimens show local strain rates which\nevolve strongly during the test (by a factor of 5-10 here). The parameter\nidentification process requires then the introduction of the exact realized\ninput strain and strain-rate command into the model. Accounting for strain rate\ndependency requires additionally the knowledge of the preliminary identified\nstrain rate dependence of the non-elastic constitutive parameters for good\npredictions of the experimental response directly. This is what is proven here.\nThe conclusion speaks in favor of a possible upgrade of international standards\nfor the mechanical characterization of polymers based on constant strain-rate\ntensile tests and properly applied model-based metrology."
    },
    {
        "anchor": "The interplay between symmetry-breaking and symmetry-preserving\n  bifurcations in soft dielectric films and the emergence of giant\n  electro-actuation: Soft elastomers that can exhibit extremely large deformations under the\naction of an electric field are essential for applications such as soft\nrobotics, stretchable and flexible electronics, energy harvesting among others.\nThe critical limiting factor in conventional electro-actuation of such\nmaterials is the occurrence of the so-called pull-in instability. In this work,\nwe demonstrate an extraordinarily simple way to coax a dielectric thin film\ntowards a symmetry-breaking pitchfork bifurcation state while avoiding pull-in\ninstability. Through the nonlinear interplay between the two bifurcation modes,\nwe predict electro-actuation strains that exceed what is conventionally\npossible by 200$\\%$, and at significantly lower applied electric fields.",
        "positive": "Use of tunable nanopore blockade rates to investigate colloidal\n  dispersions: Tunable nanopores in elastomeric membranes have been used to study the\ndependence of ionic current blockade rate on the concentration and\nelectrophoretic mobility of particles in aqueous suspensions. A range of\nnanoparticle sizes, materials and surface functionalities has been tested.\nUsing pressure-driven flow through a pore, the blockade rate for 100 nm\ncarboxylated polystyrene particles was found to be linearly proportional to\nboth transmembrane pressure (controlled between 0 and 1.8 kPa) and particle\nconcentration (between 7 x 10^8 and 4.5 x 10^10 mL^-1). This result can be\naccurately modelled using Nernst-Planck transport theory. Using only an applied\npotential across a pore, the blockade rates for carboxylic acid and amine\ncoated 500 nm and 200 nm silica particles were found to correspond to changes\nin their mobility as a function of the solution pH. Scanning electron\nmicroscopy and confocal microscopy have been used to visualise changes in the\ntunable nanopore geometry in three dimensions as a function of applied\nmechanical strain. The pores observed were conical in shape, and changes in\npore size were consistent with ionic current measurements. A zone of inelastic\ndeformation adjacent to the pore has been identified as critical in the tuning\nprocess."
    },
    {
        "anchor": "Slippage of Newtonian liquids: Influence on the dynamics of dewetting\n  thin films: Slippage of Newtonian liquids in the presence of a solid substrate is a newly\nfound phenomenon the origin of which is still under debate. In this paper, we\npresent a new analysis method to extract the slip length. Enhancing the slip of\nliquids is an important issue for microfluidic devices that demand for high\nthroughput at low pumping power. We study the velocity of short-chained liquid\npolystyrene (PS) films dewetting from non-wettable solid substrates. We show\nhow the dynamics of dewetting is influenced by slippage and we compare the\nresults of two types of substrates that give rise to different slip lengths. As\nsubstrates, Si wafers were used that have been coated by\noctadecyl-trichlorosilane (OTS) or dodecyl-trichlorosilane (DTS), respectively.\nOur results demonstrate that the dewetting velocity for PS films on DTS is\nsignificantly larger than on OTS and that this difference originates from the\ndifferent slip lengths of the liquid on top of the two surfaces. For PS films\nof thicknesses between 130 nm and 230 nm we find slip lengths between 400 nm\nand 600 nm, depending on substrate and temperature.",
        "positive": "Long wavelength structural anomalies in jammed systems: The structural properties of static, jammed packings of monodisperse spheres\nin the vicinity of the jamming transition are investigated using large-scale\ncomputer simulations. At small wavenumber $k$, we argue that the anomalous\nbehavior in the static structure factor, $S(k) \\sim k$, is consequential of an\nexcess of low-frequency, collective excitations seen in the vibrational\nspectrum. This anomalous feature becomes more pronounced closest to the jamming\ntransition, such that $S(0) \\to 0$ at the transition point. We introduce an\nappropriate dispersion relation that accounts for these phenomena that leads us\nto relate these structural features to characteristic length scales associated\nwith the low-frequency vibrational modes of these systems. When the particles\nare frictional, this anomalous behavior is suppressed providing yet more\nevidence that jamming transitions of frictional spheres lie at lower packing\nfractions that that for frictionless spheres. These results suggest that the\nmechanical properties of jammed and glassy media may therefore be inferred from\nmeasurements of both the static and dynamical structure factors."
    },
    {
        "anchor": "Interfacial motion in flexo- and order-electric switching between\n  nematic filled states: We consider a nematic liquid crystal, in coexistence with its isotropic\nphase, in contact with a substrate patterned with rectangular grooves. In such\na system, the nematic phase may fill the grooves without the occurrence of\ncomplete wetting. There may exist multiple (meta)stable filled states, each\ncharacterised by the type of distortion (bend or splay) in each corner of the\ngroove and by the shape of the nematic-isotropic interface, and additionally\nthe plateaux that separate the grooves may be either dry or wet with a thin\nlayer of nematic. Using numerical simulations, we analyse the dynamical\nresponse of the system to an externally- applied electric field, with the aim\nof identifying switching transitions between these filled states. We find that\norder-electric coupling between the fluid and the field provides a means of\nswitching between states where the plateaux between grooves are dry and states\nwhere they are wet by a nematic layer, without affecting the configuration of\nthe nematic within the groove. We find that flexoelectric coupling may change\nthe nematic texture in the groove, provided that the flexoelectric coupling\ndifferentiates between the types of distortion at the corners of the substrate.\nWe identify intermediate stages of the transitions, and the role played by the\nmotion of the nematic-isotropic interface. We determine quantitatively the\nfield magnitudes and orientations required to effect each type of transition.",
        "positive": "Structural heterogeneity and its role in determining properties of\n  disordered solids: We construct a new order parameter from the normal modes of vibration, based\non the consideration of energy equipartition, to quantify the structural\nheterogeneity in disordered solids. The order parameter exhibits strong spatial\ncorrelations with low-temperature single particle dynamics and local structural\nentropy. To characterize the role of particles with the most defective local\nstructures identified by the order parameter, we pin them and study how\nproperties of disordered solids respond to the pinning. It turns out that these\nparticles are responsible to the quasilocalized low-frequency vibration,\ninstability, softening, and nonaffinity of disordered solids."
    },
    {
        "anchor": "Single artificial-atom lasing: Solid-state superconducting circuits are versatile systems in which quantum\nstates can be engineered and controlled. Recent progress in this area has\nopened up exciting possibilities for exploring fundamental physics as well as\napplications in quantum information technology; in a series of experiments it\nwas shown that such circuits can be exploited to generate quantum optical\nphenomena, by designing superconducting elements as artificial atoms that are\ncoupled coherently to the photon field of a resonator. Here we demonstrate a\nlasing effect with a single artificial atom - a Josephson-junction charge qubit\n- embedded in a superconducting resonator. We make use of one of the properties\nof solid-state artificial atoms, namely that they are strongly and controllably\ncoupled to the resonator modes. The device is essentially different from\nexisting lasers and masers; one and the same artificial atom excited by current\ninjection produces many photons.",
        "positive": "Shear-induced sedimentation in yield stress fluids: Stability of coarse particles against gravity is an important issue in dense\nsuspensions (fresh concrete, foodstuff, etc.). On the one hand, it is known\nthat they are stable at rest when the interstitial paste has a high enough\nyield stress; on the other hand, it is not yet possible to predict if a given\nmaterial will remain homogeneous during a flow. Using MRI techniques, we study\nthe time evolution of the particle volume fraction during the flows in a\nCouette geometry of model density-mismatched suspensions of noncolloidal\nparticles in yield stress fluids. We observe that shear induces sedimentation\nof the particles in all systems, which are stable at rest. The sedimentation\nvelocity is observed to increase with increasing shear rate and particle\ndiameter, and to decrease with increasing yield stress of the interstitial\nfluid. At low shear rate ('plastic regime'), we show that this phenomenon can\nbe modelled by considering that the interstitial fluid behaves like a viscous\nfluid -- of viscosity equal to the apparent viscosity of the sheared fluid --\nin the direction orthogonal to shear. The behavior at higher shear rates, when\nviscous effects start to be important, is also discussed. We finally study the\ndependence of the sedimentation velocity on the particle volume fraction, and\nshow that its modelling requires estimating the local shear rate in the\ninterstitial fluid."
    },
    {
        "anchor": "Scaling properties of centering forces: Motivated by the centering of biological objects in large cells, we study the\ngeneric properties of centering forces inside a ball (or a volume of spherical\ntopology) in $n$ dimensions. We consider two scenarios : autonomous centering\n(in which distance information is integrated from the agent perspective) and\nnon-autonomous centering (in which distance to the surface is integrated over\nthe whole surface). We find relations between the net centering force and the\nmean distance$^p$ to the surface. This allows us to find simple scaling laws\nbetween the centering force and the distance to the center, as a function of\nthe dimensionality $n$. Interestingly, if the interactions between the agent\nand the surface are hyper-elastic, the net centering force can still be\nsub-elastic in the case of autonomous centering. These scaling laws are\nincreasingly violated as the space becomes less convex. Generically, neither\nscenarios exactly converge to the center of mass of the space.",
        "positive": "Optical Control Of Mass Ejection From Ferroelectric Liquid Droplets: A\n  Possible Tool For The Actuation Of Complex Fluids: We report on the optical control of the recently observed electromechanical\ninstability of ferroelectric liquid droplets exposed to the photovoltaic field\nof a lithium niobate ferroelectric crystal substrate. The ferroelectric liquid\nis a nematic liquid crystal in which almost complete polar ordering of the\nmolecular dipoles generates an internal macroscopic polarization locally\ncollinear to the mean molecular long axis. Upon entering the ferroelectric\nphase, droplets irradiated by unfocused beam undergo an electromechanical\ninstability and disintegrate by the explosive emission of fluid jets. We show\nhere that the regions of jets emission can be controlled by focusing the light\nbeam in areas close to the droplet's edge. Once emitted, the fluid jets can be\nwalked by moving the beam up to millimeter distance from the mother droplet.\nReverting the lithium niobate substrate, jets become thinner and show the\ntendency of being repelled by the beam instead of being attracted, thus\noffering an additional tool for their optical manipulation. These observations\nmay pave the way to intriguing applications of ferroelectric nematic fluids\nrelated to manipulation, actuation, and control of soft, flexible materials."
    },
    {
        "anchor": "Hydrodynamic instabilities in a 2-D sheet of microswimmers embedded in a\n  3-D fluid: A collection of microswimmers immersed in an incompressible fluid is\ncharacterised by strong interactions due to the long-range nature of the\nhydrodynamic fields generated by individual organisms. As a result, suspensions\nof rear-actuated `pusher' swimmers such as bacteria exhibit a collective motion\nstate often referred to as `bacterial turbulence', characterised by large-scale\nchaotic flows. The onset of collective motion in pusher suspensions is\nclassically understood within the framework of mean-field kinetic theories for\ndipolar swimmers. In bulk 2-D and 3-D, the theory predicts that the instability\nleading to bacterial turbulence is due to mutual swimmer reorientation and sets\nin at the largest length scale available to the suspension. Here, we construct\na similar kinetic theory for the case of a dipolar microswimmer suspension\nrestricted to a two-dimensional plane embedded in a three-dimensional\nincompressible fluid. This setting qualitatively mimics the effect of swimming\nclose to a two-dimensional interface. We show that the in-plane flow fields are\neffectively compressible in spite of the incompressibility of the 3-D bulk\nfluid, and that microswimmers on average act as sources (pushers) or sinks\n(pullers). We analyse stability of the homogeneous and isotropic state, and\nfind two types of instability that are qualitatively different from the bulk,\nthree-dimensional case: First, we show that the analogue of the orientational\npusher instability leading to bacterial turbulence in bulk systems instead\noccurs at the smallest length-scale available to the system. Second, an\ninstability associated with density variations arises in puller suspensions as\na generic consequence of the effective in-plane compressibility. We conclude\nthat confinement can have a crucial role in determining the collective\nbehaviour of microswimmer suspensions.",
        "positive": "Does twist angle affect the properties of water confined inside twisted\n  bilayer graphene?: Graphene nanoslit pore is used for nanofluidic devices like water\ndesalination, ion-selective channels, ionic transistors, sensing, molecular\nsieving, blue energy harvesting, and protein sequencing. It is a strenuous task\nto prepare nanofluidic devices because a small misalignment leads to a\nsignificant alteration in various properties of the devices. Here we focus on\nthe rotational misalignment between two parallel graphene sheets. Using\nmolecular dynamics simulation, we probe the structure and dynamics of monolayer\nwater confined inside graphene nanochannels for a range of commensurate twist\nangles. With SPC/E and TIP4P/2005 water model, our simulations reveal the\nindependence of equilibrium number density $(n \\sim 13 nm^{-2})$ for SPC/E and\n$(n \\sim 11.5 nm^{-2})$ for TIP4P/2005) across twists. Based on the respective\ndensities of water models, the structure and dielectric constant are invariant\nof twist angles. The confined water structure at this shows square ice ordering\nfor SPC/E water only. TIP4P/2005 shows ordering at the vicinity of a critical\ndensity $(n \\sim 12.5 nm^{-2})$. The average perpendicular dielectric constant\nof the confined water remains anomalously low ($\\sim 2$ for SPC/E and $\\sim 6$\nfor TIP4P/2005) for studied twist angles. We find that the friction coefficient\nof confined water molecules varies for small twist angles while becoming\nindependent for twists greater than $5.1^{o}$. Our results indicate that small\nangular misalignment will not impair the dielectric properties of monolayer\nwater within graphene slit-pore but can significantly influence its dynamics."
    },
    {
        "anchor": "Maximum Likelihood Estimation for Single Particle, Passive Microrheology\n  Data with Drift: Volume limitations and low yield thresholds of biological fluids have led to\nwidespread use of passive microparticle rheology. The mean-squared-displacement\n(MSD) statistics of bead position time series (bead paths) are either applied\ndirectly to determine the creep compliance [Xu et al (1998)] or transformed to\ndetermine dynamic storage and loss moduli [Mason & Weitz (1995)]. A prevalent\nhurdle arises when there is a non-diffusive experimental drift in the data.\nCommensurate with the magnitude of drift relative to diffusive mobility,\nquantified by a P\\'eclet number, the MSD statistics are distorted, and thus the\npath data must be \"corrected\" for drift. The standard approach is to estimate\nand subtract the drift from particle paths, and then calculate MSD statistics.\nWe present an alternative, parametric approach using maximum likelihood\nestimation that simultaneously fits drift and diffusive model parameters from\nthe path data; the MSD statistics (and consequently the compliance and dynamic\nmoduli) then follow directly from the best-fit model. We illustrate and compare\nboth methods on simulated path data over a range of P\\'eclet numbers, where\nexact answers are known. We choose fractional Brownian motion as the numerical\nmodel because it affords tunable, sub-diffusive MSD statistics consistent with\ntypical 30 second long, experimental observations of microbeads in several\nbiological fluids. Finally, we apply and compare both methods on data from\nhuman bronchial epithelial cell culture mucus.",
        "positive": "Mechanical excitation and marginal triggering during avalanches in\n  sheared amorphous solids: We study plastic strain during individual avalanches in overdamped\nparticle-scale molecular dynamics (MD) and meso-scale elasto-plastic models\n(EPM) for amorphous solids sheared in the athermal quasi-static limit. We show\nthat the spatial correlations in plastic activity exhibit a short lengthscale\nthat grows as $t^{3/4}$ in MD and ballistically in EPM, and is generated by\nmechanical excitation of nearby sites not necessarily close to their stability\nthresholds, and a longer lengthscale that grows diffusively for both models and\nis associated with remote marginally stable sites. These similarities in\nspatial correlations explain why simple EPMs accurately capture the size\ndistribution of avalanches observed in MD, though the temporal profiles and\ndynamical critical exponents are quite different."
    },
    {
        "anchor": "Density scaling and quasiuniversality of flow-event statistics for\n  athermal plastic flows: Athermal plastic flows were simulated for the Kob-Andersen binary\nLennard-Jones system and its repulsive version in which the sign of the\nattractive terms is changed to a plus. Properties evaluated from simulations at\ndifferent densities include the distributions of energy drops, stress drops,\nand strain intervals between the flow events. By reference to hidden scale\ninvariance we show that simulations at a single density in conjunction with an\nequilibrium-liquid simulation at the same density allows one to predict the\nplastic flow-event properties at other densities. We furthermore demonstrate\nquasiuniversality of the flow-event statistics.",
        "positive": "How a liquid becomes a glass both on cooling and on heating: The onset of structural arrest and glass formation in a concentrated\nsuspension of silica nanoparticles in a water-lutidine binary mixture near its\nconsolute point is studied by exploiting the near-critical fluid degrees of\nfreedom to control the strength of an attraction between particles and\nmultispeckle x-ray photon correlation spectroscopy to determine the particles'\ncollective dynamics. This model system undergoes a glass transition both on\ncooling and on heating, and the intermediate liquid realizes unusual\nlogarithmic relaxations. How vitrification occurs for the two different glass\ntransitions is characterized in detail and comparisons are drawn to recent\ntheoretical predictions for glass formation in systems with attractive\ninteractions."
    },
    {
        "anchor": "Forces between Silica Particles in Isopropanol Solutions of 1:1\n  Electrolytes: Interactions between silica surfaces across isopropanol solutions are\nmeasured with colloidal probe technique based on atomic force microscope. In\nparticular, the influence of 1:1 electrolytes on the interactions between\nsilica particles is investigated. A plethora of different forces are found in\nthese systems. Namely, van der Waals, double-layer, attractive non-DLVO,\nrepulsive solvation, and damped oscillatory interactions are observed. The\nmeasured decay length of the double-layer repulsion is substantially larger\nthan Debye lengths calculated from nominal salt concentrations. These\ndeviations are caused by pronounced ion pairing in alcohol solutions. At\nseparation below 10 nm, additional attractive and repulsive non-DLVO forces are\nobserved. The former are possibly caused by charge heterogeneities induced by\nstrong ion adsorption, whereas the latter originate from structuring of\nisopropanol molecules close to the surface. Finally, at increased\nconcentrations the transition from monotonic to damped oscillatory interactions\nis uncovered.",
        "positive": "Identification of Characteristic Protein Folding Channels in a\n  Coarse-Grained Hydrophobic-Polar Peptide Model: Folding channels and free-energy landscapes of hydrophobic-polar\nheteropolymers are discussed on the basis of a minimalistic off-lattice\ncoarse-grained model. We investigate how rearrangements of hydrophobic and\npolar monomers in a heteropolymer sequence lead to completely different folding\nbehaviors. Studying three exemplified sequences with the same content of\nhydrophobic and polar residues, we can reproduce within this simple model\ntwo-state folding, folding through intermediates, as well as metastability."
    },
    {
        "anchor": "Shear-thinning in Polymer Melts -- Molecular Origins and Hybrid\n  Multiscale Simulations: We investigate the molecular origin of shear-thinning in melts of flexible,\nsemiflexible and rigid oligomers with coarse-grained simulations of a sheared\nmelt. Alignment, stretching and tumbling modes or suppression of the latter all\ncontribute to understanding how macroscopic flow properties emerge from the\nmolecular level. By performing simulations of single chains in a shear flow, we\nidentify which of these phenomena are of collective nature and arise through\ninterchain interactions and which are already present in dilute systems.\nBuilding upon these microscopic simulations we identify by means of the\nIrving-Kirkwood formula the corresponding macroscopic stress tensor for a\nnon-Newtonian polymer fluid. Shear-thinning effects in oligomer melts are also\ndemonstrated by macroscopic simulations of a channel flow. The latter have been\nobtained by the discontinuous Galerkin method approximating macroscopic polymer\nflows. Our study confirms the influence of microscopic details in the molecular\nstructure of short polymers such as chain flexibility on macroscopic polymer\nflows.",
        "positive": "Particle-surface interactions in a uniform electric field: The electrostatic force on a spherical particle near a planar surface is\ncalculated for the cases of a uniform electric field applied in either normal\nor tangential direction to the surface. The particle and suspending media are\nassumed to be weakly conducting, so that that the leaky dielectric model\napplies. The Laplace equation for the electric potential is solved in bipolar\ncoordinate system and the potential is obtained in terms of a series expansion\nof Legendre polynomials. The force on the particle is calculated using the\nMaxwell tensor. We find that in the case of normal electric field, which\ncorresponds to a particle near an electrode, the force is always attractive but\nat a given separation it varies nontrivially with particle-suspending medium\nconductivity ratio; the force on a particle that is more conducting than the\nsuspending medium is much larger compared to the force on a particle less\nconducing than the suspending medium. In the case of tangential electric field,\nwhich corresponds to a particle near an insulating boundary, the force is\nalways repulsive."
    },
    {
        "anchor": "Design principles for textured multi-layered composites using\n  magnetically assisted slip casting: In many natural multi-layered composites, such as in the dactyl club of\nStomatopods or the shell of bivalve mollusks, the defining functional and\nstructural properties are determined by locally varying orientations of\ninorganic building blocks within each layer. One approach to artificially\nproduce textured microstructures inspired by such complex composites is\nmagnetically assisted slip-casting (MASC). MASC is a colloidal process in which\nanisotropic particles are oriented at arbitrarily defined angles using a\nmagnetic field. The orientation of the particles is maintained during growth as\nparticles are collected from the wall of a porous mold. Whereas a number of\nproof-of-concept studies have established the potential of the technique, the\nfull design space available for MASC-fabricated structures, and the limits of\nthe approach, have so far not been explored in a systematic manner. To fill\nthis gap, we have studied both theoretically and experimentally the various\ntorques that act on the particles at different stage of the assembly process.\nWe define the boundary conditions of the MASC process for magnetically\nresponsive alumina platelets suspended in a low-viscosity aqueous suspension,\nconsidering the composition of the colloidal suspension and the dynamics of the\nparticle-alignment process under a rotating magnetic field. Taken together,\nthese findings define a design strategy for the fabrication of designed\nmulti-lamellar microstructures using MASC. Our guidelines are based on a\ncomprehensive understanding of the physical mechanisms governing the\norientation and assembly of anisotropic particles during MASC and indicate a\nroute to expanding this technique to building blocks of various chemistries,\nand thus to broadening the range of bio-inspired composites with customized\nmulti-scale structures that can be produced for specific applications.",
        "positive": "Enhanced Phonon Peak in Four-point Dynamic Susceptibility in the\n  Supercooled Active Glass-forming Liquids: Active glassy systems can be thought of as simple model systems that imitate\ncomplex biological systems. Sometimes, it becomes crucial to estimate the\namount of the activity present in such biological systems, such as predicting\nthe progression rate of the cancer cells or the healing time of the wound. In\nthis work, we study a model active glassy system to understand a possible\nquantification of the degree of activity from the collective, long-range phonon\nresponse in the system. We find that the four-point dynamic susceptibility,\n$\\chi_4(t)$ at the phonon timescale, grows with increased activity. We then\nshow how one can estimate the degree of the activity at such a small timescale\nby measuring the growth of $\\chi_4(t)$ with changing activity. A detailed\nfinite size analysis of this measurement, shows that the peak height of\n$\\chi_4(t)$ at this phonon timescale increases strongly with increasing system\nsize suggesting a possible existence of an intrinsic dynamic length scale that\ngrows with increasing activity. Finally, we show that this peak height is a\nunique function of effective activity across all system sizes, serving as a\npossible parameter for characterizing the degree of activity in a system."
    },
    {
        "anchor": "DNA nanotweezers studied with a coarse-grained model of DNA: We introduce a coarse-grained rigid nucleotide model of DNA that reproduces\nthe basic thermodynamics of short strands: duplex hybridization,\nsingle-stranded stacking and hairpin formation, and also captures the essential\nstructural properties of DNA: the helical pitch, persistence length and\ntorsional stiffness of double-stranded molecules, as well as the comparative\nflexibility of unstacked single strands. We apply the model to calculate the\ndetailed free-energy landscape of one full cycle of DNA 'tweezers', a simple\nmachine driven by hybridization and strand displacement.",
        "positive": "Technical Brief: Finite Element Modeling of Tight Elastic Knots: We present a methodology to simulate the mechanics of knots in elastic rods\nusing geometrically nonlinear, full three-dimensional (3D) finite element\nanalysis. We focus on the mechanical behavior of knots in tight configurations,\nfor which the full 3D deformation must be taken into account. To set up the\ntopology of our knotted structures, we apply a sequence of prescribed\ndisplacement steps to the centerline of an initially straight rod that is\nmeshed with 3D solid elements. Self-contact is enforced with a normal penalty\nforce combined with Coulomb friction. As test cases, we investigate both\noverhand and figure-of-eight knots. Our simulations are validated with\nprecision model experiments, combining rod fabrication and X-ray tomography.\nEven if the focus is given to the methods, our results reveal that 3D\ndeformation of tight elastic knots is central to their mechanical response.\nThese findings contrast to a previous analysis of loose knots, for which 1D\ncenterline-based rod theories sufficed for a predictive understanding. Our\nmethod serves as a robust framework to access complex mechanical behavior of\ntightly knotted structures that are not readily available through experiments\nnor existing reduced-order theories."
    },
    {
        "anchor": "Size-dependent effects in solutions of small metal nanoparticles: A new theoretical approach for the calculation of optical properties of\ncomplex solutions is proposed. It is based on a dielectric matrix with included\nsmall metallic inclusions (less than 3 nm) of spherical shape. We take into\naccount the mutual interactions between the inclusions and the quantum\nfinite-size effects. On the basis of the effective medium model, TDLDA and\nKohn-Sham theories, some analytical expressions for the effective dielectric\npermittivity of the solution are obtained.",
        "positive": "Efficient and accurate simulations of deformable particles immersed in a\n  fluid using a combined immersed boundary lattice Boltzmann finite element\n  method: The deformation of an initially spherical capsule, freely suspended in simple\nshear flow, can be computed analytically in the limit of small deformations [D.\nBarthes-Biesel, J. M. Rallison, The Time-Dependent Deformation of a Capsule\nFreely Suspended in a Linear Shear Flow, J. Fluid Mech. 113 (1981) 251-267].\nThose analytic approximations are used to study the influence of the mesh\ntessellation method, the spatial resolution, and the discrete delta function of\nthe immersed boundary method on the numerical results obtained by a coupled\nimmersed boundary lattice Boltzmann finite element method. For the description\nof the capsule membrane, a finite element method and the Skalak constitutive\nmodel [R. Skalak et al., Strain Energy Function of Red Blood Cell Membranes,\nBiophys. J. 13 (1973) 245-264] have been employed. Our primary goal is the\ninvestigation of the presented model for small resolutions to provide a sound\nbasis for efficient but accurate simulations of multiple deformable particles\nimmersed in a fluid. We come to the conclusion that details of the membrane\nmesh, as tessellation method and resolution, play only a minor role. The\nhydrodynamic resolution, i.e., the width of the discrete delta function, can\nsignificantly influence the accuracy of the simulations. The discretization of\nthe delta function introduces an artificial length scale, which effectively\nchanges the radius and the deformability of the capsule. We discuss\npossibilities of reducing the computing time of simulations of deformable\nobjects immersed in a fluid while maintaining high accuracy."
    },
    {
        "anchor": "Evidence of hydrodynamic and subdiffusive motion of tracers in a\n  viscoelastic medium: We propose a theoretical model which relies on the generalized Langevin\nequation and may account for various dynamical features of the thermal motion\nof organelles, vesicles or macromolecules in viscoelastic media such as polymer\nnetworks. In particular, we consider inertial and hydrodynamic effects at short\ntimes, subdiffusive scaling at intermediate times, and eventually optical\ntrapping at long times. Simple analytical formulas for the mean square\ndisplacement and velocity auto-correlation function are derived. The developed\ntheory is applied to the analysis of fifty-second long trajectories of\nmicron-sized spherical tracers in actin gels that were acquired at one\nmicrosecond temporal resolution by using optical tweezers single-particle\ntracking. For the first time, both the subdiffusive scaling and hydrodynamic\neffects are observed within a single experiment and accurately described by a\nminimal phenomenological model.",
        "positive": "Canonical Simulation Methodology to Extract Phase Boundaries of Liquid\n  Crystalline Polymer Mixtures: We report a novel multi-scale simulation methodology to quantitatively\npredict the thermodynamic behaviour of polymer mixtures, that exhibit phases\nwith broken orientational symmetry. Our system consists of a binary mixture of\noligomers and rod-like mesogens. Using coarse-grained molecular dynamics (CGMD)\nsimulations we infer the topology of the temperature-dependent free energy\nlandscape from the probability distributions of excess volume fraction of the\ncomponents. The mixture exhibits nematic and smectic phases as a function of\ntwo temperature scales, the nematic-isotropic temperature $T_{NI}$ and the\n$T_c$, the transition that governs the polymer demixing. Using a mean-field\nfree energy of polymer-dispersed liquid crystals (PDLCs), with suitably chosen\nparameter values, we construct a mean-field phase diagram that\nsemi-quantitatively match those obtained from CGMD simulations. Our results are\napplicable to mixtures of synthetic and biological macromolecules that undergo\nphase separation and are orientable, thereby giving rise to the liquid\ncrystalline phases."
    },
    {
        "anchor": "Defect modes of a Bose-Einstein condensate in an optical lattice with a\n  localized impurity: We study defect modes of a Bose-Einstein condensate in an optical lattice\nwith a localized defect within the framework of the one-dimensional\nGross-Pitaevskii equation. It is shown that for a significant range of\nparameters the defect modes can be accurately described by an expansion over\nWannier functions, whose envelope is governed by the coupled nonlinear\nSchr\\\"{o}dinger equation with a delta-impurity. The stability of the defect\nmodes is verified by direct numerical simulations of the underlying\nGross-Pitaevskii equation with a periodic plus defect potentials. We also\ndiscuss possibilities of driving defect modes through the lattice and suggest\nideas for their experimental generation.",
        "positive": "Evidence for out-of-equilibrium crystal nucleation in suspensions of\n  oppositely charged colloids: We report a numerical study of the rate of crystal nucleation in a binary\nsuspension of oppositely charged colloids. Two different crystal structures\ncompete in the thermodynamic conditions under study. We find that the crystal\nphase that nucleates is metastable and, more surprisingly, its nucleation free\nenergy barrier is not the lowest one. This implies that, during nucleation,\nthere is insufficient time for sub-critical nuclei to relax to their lowest\nfree-energy structure. Such behavior is in direct contradiction with the common\nassumption that the phase that crystallizes most readily is the one with the\nlowest free-energy barrier for nucleation. The phenomenon that we describe\nshould be relevant for crystallization experiments where competing solid\nstructures are not connected by an easy transformation."
    },
    {
        "anchor": "X-LoRA: Mixture of Low-Rank Adapter Experts, a Flexible Framework for\n  Large Language Models with Applications in Protein Mechanics and Design: We report a mixture of expert strategy to create fine-tuned large language\nmodels using a deep layer-wise token-level approach based on low-rank\nadaptation (LoRA). Starting with a set of pre-trained LoRA adapters, we propose\na gating strategy that uses the hidden states to dynamically mix adapted\nlayers, allowing the resulting X-LoRA model to draw upon different capabilities\nand create never-before-used deep layer-wise combinations of adaptations are\nestablished to solve specific tasks. The design is inspired by the biological\nprinciples of universality and diversity, where neural network building blocks\nare reused in different hierarchical manifestations. Hence, the X-LoRA model\ncan be easily implemented for any existing large language model (LLM) without a\nneed for modifications of the underlying structure. We develop a tailored\nX-LoRA model that offers scientific capabilities including forward/inverse\nanalysis tasks and enhanced reasoning capability, focused on biomaterial\nanalysis, protein mechanics and design. The impact of this work include access\nto readily expandable, adaptable and changeable models with strong domain\nknowledge and the capability to integrate across areas of knowledge. With the\nX-LoRA model featuring experts in biology, mathematics, reasoning, bio-inspired\nmaterials, mechanics and materials, chemistry, and protein mechanics we conduct\na series of physics-focused case studies. We examine knowledge recall, protein\nmechanics forward/inverse tasks, protein design, and adversarial agentic\nmodeling including ontological knowledge graphs. The model is capable not only\nof making quantitative predictions of nanomechanical properties of proteins,\nbut also reasons over the results and correctly predicts likely mechanisms that\nexplain distinct molecular behaviors.",
        "positive": "Reconfiguration Dynamics in folded and intrinsically disordered protein\n  with internal friction: Effect of solvent quality and denaturant: We consider a phantom chain model of polymer with internal friction in a\nharmonic confinement and extend it to take care of effects of solvent quality\nfollowing a mean field approach where an exponent $\\nu$ is introduced. The\nmodel termed as \"Solvent Dependent Compacted Rouse with Internal Friction\n(SDCRIF)\" is then used to calculate the reconfiguration time of a chain that\nrelates to recent F\\\"{o}rster resonance energy transfer (FRET) studies on\nfolded and intrinsically disordered proteins (IDPs) and can account for the\neffects of solvent quality as well as the denaturant concentration on the\nreconfiguration dynamics. Following an ansatz that relates the strength of the\nharmonic confinement ($k_c$) with the internal friction of the chain\n($\\xi_{int}$), SDCRIF can convincingly reproduce the experimental data and\nexplain how the denaturant can change the time scale for the internal friction.\nIt can also predict near zero internal friction in case of IDPs. In addition,\nour calculations show that the looping time as well as the reconfiguration time\nscales with the chain length $N$ as $\\sim N^\\alpha$, where $\\alpha$ depends\nweakly on the internal friction but has rather stronger dependence on the\nsolvent quality. In absence of any internal friction, $\\alpha=2\\nu+1$ and it\ngoes down in presence of internal friction, but looping slows down in general.\nOn the contrary, poorer the solvent, faster the chain reconfigures and forms\nloop, even though one expects high internal friction in the collapsed state.\nHowever, if the internal friction is too high then the looping and\nreconfiguration dynamics become slow even in poor solvent."
    },
    {
        "anchor": "Viscosity, heat conductivity and Prandtl number effects in\n  Rayleigh-Taylor Instability: Two-dimensional Rayleigh-Taylor(RT) instability problem is simulated with a\nmultiple-relaxation-time discrete Boltzmann model with gravity term. The\nviscosity, heat conductivity and Prandtl number effects are probed from the\nmacroscopic and the non-equilibrium views. In macro sense, both viscosity and\nheat conduction show significant inhibitory effect in the reacceleration stage,\nand the inhibition effect is mainly achieved by inhibiting the development of\nKelvin-Helmholtz instability. Before this, the Prandtl number effect is not\nsensitive. Based on the view of non-equilibrium, the viscosity, heat\nconductivity, and Prandtl number effects on non-equilibrium manifestations, and\nthe correlation degrees between the non-uniformity and the non-equilibrium\nstrength in the complex flow are systematic investigated.",
        "positive": "Quantum motion of charges in $\u03c0$-conjugated polymers: kinkiness\n  induces localization: We develop a model for charge trapping on conjugated polymer chains using a\ncontinuous representation of the polymer. By constraining the motion to along\nthe chain, we find that kinks along the chain serve as points of attraction and\ncan induce localization and spontaneous buckling of the chain. We implement\nthis in a model system of a conjugated polymer donor and fullerene acceptor to\nmimic a polymer based photovoltaic system. We find that geometric fluctuations\nof the polymer give rise to deep potential energy traps at kinks which are\noften stronger than the Coulomb interaction between the electron and hole."
    },
    {
        "anchor": "Self-Organization in a Granular Medium by Internal Avalanches: Internal avalanches of grain displacements can be created inside a granular\nmaterial kept in a bin in two ways: (i) By removing a radomly selected grain at\nthe bottom of the bin (ii) By breaking a stable arch of grains clogging a hole\nat the bottom of the bin. Repeated generations of such avalanches lead the\nsystem to a steady state. The question asked, is this state a critical state as\nthat in Self-Organized Criticality? We review here some of the recent studies\non this problem using cellular automata as well as hard disc models.",
        "positive": "Finite-size effects on sound damping in stable computer glasses: In this brief note we comment on the recent results presented in\narXiv:1812.08736v1"
    },
    {
        "anchor": "Self-assembling DNA-caged particles: nanoblocks for hierarchical\n  self-assembly: DNA is an ideal candidate to organize matter on the nanoscale, primarily due\nto the specificity and complexity of DNA based interactions. Recent advances in\nthis direction include the self-assembly of colloidal crystals using DNA\ngrafted particles. In this article we theoretically study the self-assembly of\nDNA-caged particles. These nanoblocks combine DNA grafted particles with more\ncomplicated purely DNA based constructs. Geometrically the nanoblock is a\nsphere (DNA grafted particle) inscribed inside a polyhedron (DNA cage). The\nfaces of the DNA cage are open, and the edges are made from double stranded\nDNA. The cage vertices are modified DNA junctions. We calculate the\nequilibriuim yield of self-assembled, tetrahedrally caged particles, and\ndiscuss their stability with respect to alternative structures. The\nexperimental feasability of the method is discussed. To conclude we indicate\nthe usefulness of DNA-caged particles as nanoblocks in a hierarchical\nself-assembly strategy.",
        "positive": "Achiral symmetry breaking and positive Gaussian modulus lead to\n  scalloped colloidal membranes: In the presence of a non-adsorbing polymer, monodisperse rod-like particles\nassemble into colloidal membranes, which are one rod-length thick liquid-like\nmonolayers of aligned rods. Unlike 3D edgeless bilayer vesicles, colloidal\nmonolayer membranes form open structures with an exposed edge, thus presenting\nan opportunity to study physics of thin elastic sheets. Membranes assembled\nfrom single-component chiral rods form flat disks with uniform edge twist. In\ncomparison, membranes comprised of mixture of rods with opposite chiralities\ncan have the edge twist of either handedness. In this limit disk-shaped\nmembranes become unstable, instead forming structures with scalloped edges,\nwhere two adjacent lobes with opposite handedness are separated by a\ncusp-shaped point defect. Such membranes adopt a 3D configuration, with cusp\ndefects alternatively located above and below the membrane plane. In the\nachiral regime the cusp defects have repulsive interactions, but away from this\nlimit we measure effective long-ranged attractive binding. A phenomenological\nmodel shows that the increase in the edge energy of scalloped membranes is\ncompensated by concomitant decrease in the deformation energy due to Gaussian\ncurvature associated with scalloped edges, demonstrating that colloidal\nmembranes have positive Gaussian modulus. A simple excluded volume argument\npredicts the sign and magnitude of the Gaussian curvature modulus that is in\nagreement with experimental measurements. Our results provide insight into how\nthe interplay between membrane elasticity, geometrical frustration and achiral\nsymmetry breaking can be used to fold colloidal membranes into 3D shapes."
    },
    {
        "anchor": "Superfluidity and collective modes in a uniform gas of Fermi atoms with\n  a Feshbach resonance: We investigate strong-coupling superfluidity in a uniform gas of Fermi atoms\nattractively interacting via quasi-molecular bosons associated with a Feshbach\nresonance. This interaction is tunable by the threshold energy $2\\nu$ of the\nFeshbach resonance, becoming large as $2\\nu$ is decreased. In recent work, we\nshowed that the enhancement of this tunable pairing interaction naturally leads\nto the BCS-BEC crossover, where the character of the superfluid phase\ntransition changes from the BCS-type to a BEC of composite bosons consisting of\npreformed Cooper-pairs and Feshbach-induced molecules. In this paper, we extend\nour previous work and study both single quasi-particles and the collective\ndynamics of the superfluid phase below Tc. We show how the superfluid order\nparameter changes from the Cooper-pair amplitude to the square root of the\nnumber of condensed molecules associated with the Feshbach resonance, as the\nthreshold energy $2\\nu$ is lowered. We also discuss the Goldstone mode\nassociated with superfluidity, and show how its character smoothly changes from\nthe Anderson-Bogoliubov phonon in the BCS regime to the Bogoliubov phonon in\nthe BEC regime in the BCS-BEC crossover. This Goldstone mode is shown to appear\nas a resonance in the spectrum of the density-density correlation function,\nwhich is experimentally accessible.",
        "positive": "Brownian microhydrodynamics of active filaments: Slender bodies capable of spontaneous motion in the absence of external\nactuation in an otherwise quiescent fluid are common in biological, physical\nand technological contexts. The interplay between the spontaneous fluid flow,\nBrownian motion, and the elasticity of the body presents a challenging\nfluid-structure interaction problem. Here, we model this problem by\napproximating the slender body as an elastic filament that can impose\nnon-equilibrium velocities or stresses at the fluid-structure interface. We\nderive equations of motion for such an active filament by enforcing momentum\nconservation in the fluid-structure interaction and assuming slow viscous flow\nin the fluid. The fluid-structure interaction is obtained, to any desired\ndegree of accuracy, through the solution of an integral equation. A simplified\nform of the equations of motion, that allows for efficient numerical solutions,\nis obtained by applying the Kirkwood-Riseman superposition approximation to the\nintegral equation. We use this form of the equation of motion to study\ndynamical steady states in free and hinged minimally active filaments. Our\nmodel provides the foundation to study collective phenomena in\nmomentum-conserving, Brownian, active filament suspensions."
    },
    {
        "anchor": "Theory of Elastic Interaction of the Colloidal Particles in the Nematic\n  Liquid Crystal Near One Wall and in the Nematic Cell: We apply the method developed in Ref. [S.B.Chernyshuk and B.I.Lev,\nPhys.Rev.E, \\textbf{81}, 041701 (2010)] for theoretical investigation of\ncolloidal elastic interactions between axially symmetric particles in the\nconfined nematic liquid crystal (NLC) near one wall and in the nematic cell\nwith thickness $L$. Both cases of homeotropic and planar director orientations\nare considered. Particularly dipole-dipole, dipole-quadrupole and\nquadrupole-quadrupole interactions of the \\textit{one} particle with the wall\nand within the nematic cell are found as well as corresponding \\textit{two\nparticle} elastic interactions. A set of new results has been predicted: the\neffective power of repulsion between two dipole particles at height $h$ near\nthe homeotropic wall is reduced gradually from inverse 3 to 5 with an increase\nof dimensionless distance $r/h$; near the planar wall - the effect of\ndipole-dipole \\textit{isotropic attraction} is predicted for large distances\n$r>r_{dd}=4.76 h$; maps of attraction and repulsion zones are crucially changed\nfor all interactions near the planar wall and in the planar cell; one dipole\nparticle in the homeotropic nematic cell was found to be shifted by the\ndistance $\\delta_{eq}$ from the center of the cell \\textit{independent} of the\nthickness $L$ of the cell. The proposed theory fits very well with experimental\ndata for the confinement effect of elastic interaction between spheres in the\nhomeotropic cell taken from [M.Vilfan et al. Phys.Rev.Lett. {\\bf 101}, 237801,\n(2008)] in the range $1\\div1000 kT$.",
        "positive": "Phase behavior near and beyond the thermodynamic stability threshold: The phase behavior of stabilized dispersions of macromolecules is most easily\ndescribed in terms of the effective interaction between the centers of mass of\nsolute particles. For molecules like polymer chains, dendrimers, etc., the\neffective pair potential is {\\em finite} at the origin, allowing \"particles\" to\nfreely interpenetrate each other. Using a double-Gaussian model (DGM) for\ndemonstration, we studied the behavior of the system as a function of the\nattraction strength $\\eta$. Above a critical strength $\\eta_{\\rm c}$, the\ninfinite-size system is Ruelle-unstable, in that it collapses to a cluster of\nfinite volume. As $\\eta_{\\rm c}$ is approached from below, the liquid-vapor\nregion exhibits an anomalous widening at low temperature, and the liquid\ndensity apparently diverges at the stability threshold. Above $\\eta_{\\rm c}$,\nthe thermodynamic plane is divided in two regions, differing in the value of\nthe {\\em average} waiting time for collapse, being finite and small on one side\nof the boundary line, while large or even infinite in the other region. Upon\nadding a small hard core to the DGM potential, stability is fully recovered and\nthe boundary line is converted to the spinodal line of a transition between\nfluid phases. We argue that the destabilization of a colloidal dispersion, as\ninduced by the addition of salt or other flocculant, finds a suggestive analogy\nin the process by which a strengthening of the attraction pushes a\nstabilized-DGM system inside the fluid-fluid spinodal region."
    },
    {
        "anchor": "On the numerical solution of a variable-coefficient Burgers equation\n  arising in granular segregation: We study a variable-coefficient Burgers equation arising in the modelling of\nsegregation of dry bidisperse granular mixtures. The equation is subject to\nnonlinear boundary conditions for the particle flux. We construct a strongly\nimplicit Crank--Nicolson type of numerical scheme for the latter equation. The\nscheme is benchmarked against a standard exact solution of kink type, showing\nsecond-order of accuracy and good discrete conservation properties. Two\nsegregation problems considered in the literature are then solved and\ndiscussed. The first is the case of a linear kinetic stress profile, which\nrenders the governing equation of constant-coefficient type, while the second\nis the case of a variable kinetic stress profile based on an expression fit to\nparticle dynamics simulation data.",
        "positive": "Stability and Adsorption Properties of Electrostatic Complexes : Design\n  of Hybrid Nanostructures for Coating Applications: We report the presence of a correlation between the bulk and interfacial\nproperties of electrostatic coacervate complexes. Complexes were obtained by\nco-assembly between cationic-neutral diblocks and oppositely charged surfactant\nmicelles or 7 nm cerium oxide nanoparticles. Light scattering and reflectometry\nmeasurements revealed that the hybrid nanoparticle aggregates were more stable\nboth through dilution and rinsing (from either a polystyrene or a silica\nsurfaces) than their surfactant counterparts. These findings were attributed to\na marked difference in critical association concentration between the two\nsystems and to the frozen state of the hybrid structures."
    },
    {
        "anchor": "Validity of point-mass model in off-resonance dynamic atomic force\n  microscopy: The quantitative measurement of viscoelasticity of nano-scaleentities is an\nimportant goal of nanotechnology research and there is considerable progress\nwith advent of dynamic Atomic Force Microscopy. The hydrodynamics of\ncantilever, the force sensor in AFM measurements, plays a pivotal role in\nquantitative estimates of nano-scale viscoelasticity. The point-mass\nmodel,wherein the AFM cantilever is approximated as a point mass with mass-less\nspring is widely used in dynamic AFM analysis and its validity, particularly in\nliquid environments, is debated. It is suggested that the cantilever must be\ntreated as a continuous rectangular beam to obtain accurate estimates of\nnano-scale viscoelasticity of materials it is probing. Here, we derived\nequations, which relate stiffness and damping coefficient of the material under\ninvestigation to measured parameters, by approximating cantilever as a point\nmass and also considering the full geometric details. These equations are\nderived for both tip-excited as well as base excited cantilevers. We have\nperformed off-resonance dynamic atomic force spectroscopy on a single protein\nmolecule to investigate the validity of widely used point-mass model. We\nperformed measurements with AFMs equipped with different cantilever excitation\nmethods as well as detection schemes to measure cantilever response. The data\nwas analyzed using both, continuous-beam model and the point-mass model. We\nfound that both models yield same results when the experiments are performed in\ntruly off-resonance regime with small amplitudes and the cantilever stiffness\nis much higher than the interaction stiffness. Our findings suggest that a\nsimple point-mass approximation based model is adequate to describe the\ndynamics, provided care is taken while performing experiments so that the\napproximations used in these models are valid.",
        "positive": "Filled Colloidal Gel Rheology: Strengthening, Softening, and Tuneability: Filler-induced strengthening is ubiquitous in material science and is\nparticularly well-established in polymeric nanocomposites. Despite having\nsimilar constituents, colloidal gels with solid filling exhibit distinct\nrheology, which is poorly understood. We show using experiments and simulations\nthat filling monotonically enhances the yield stress of colloidal gels, while\nthe elastic modulus first increases before decreasing. The latter effect\nresults from a disturbed gel matrix at dense filling, evidenced by a growing\ninter-phase stress. This structural frustration is, however, not detrimental to\nyielding resistance. Instead, fillers offer additional mechanical support to\nthe gel backbone via percolating force chains, at the same time decreasing the\nyield strain. We develop a mechanistic picture of this phenomenology that leads\nus to a novel `filler-removal protocol,' making possible individual control\nover the strength and brittleness of a composite gel."
    },
    {
        "anchor": "Spatiotemporal Chaotic unjamming and jamming in granular avalanches: We have investigated the spatiotemporal chaotic dynamics of unjamming and\njamming of particles in a toy-model system -- a rotating drum partially filled\nwith bidisperse disks to create avalanches. The magnitudes of the first\nLyapunov vector $\\delta u(t)$ and velocity $v(t)$ of particles are directly\nmeasured for the first time to yield insights into their spatial correlation\n$C_{\\delta u,v}$, which is stronger near the unjamming but is weaker near the\njamming transition, consistent with the recent work of Banigan et al., Nature\nPhys. $\\bf{9}$, 288, (2013). $v(t)$ shows rich dynamics: it grows exponentially\nfor unstable particles and keeps increasing despite stochastic interactions;\nafter the maximum, it decays with large fluctuations. Hence the spatiotemporal\nchaotic dynamics of avalanche particles are entangled, causing temporal\ncorrelations of macroscopic quantities of the system. We propose a simple model\nfor these observations.",
        "positive": "Crystallization of hard spheres revisited. I. Extracting kinetics and\n  free energy landscape from forward flux sampling: We investigate the kinetics and the free energy landscape of the\ncrystallization of hard spheres from a supersaturated metastable liquid though\ndirect simulations and forward flux sampling. In this first paper, we describe\nand test two different ways to reconstruct the free energy barriers from the\nsampled steady state probability distribution of cluster sizes without sampling\nthe equilibrium distribution. The first method is based on mean first passage\ntimes, the second on splitting probabilities. We verify both methods for a\nsingle particle moving in a double-well potential. For the nucleation of hard\nspheres, these methods allow to probe a wide range of supersaturations, and to\nreconstruct the kinetics and the free energy landscape from the same\nsimulation. Results are consistent with the scaling predicted by classical\nnucleation theory although a quantitative fit requires a rather large,\neffective interfacial tension."
    },
    {
        "anchor": "Simulation of Charged Systems in Heterogeneous Dielectric Media via a\n  True Energy Functional: For charged systems in heterogeneous dielectric media, a key obstacle for\nmolecular dynamics (MD) simulations is the need to solve the Poisson equation\nin the media. This obstacle can be bypassed using MD methods that treat the\nlocal polarization charge density as a dynamic variable, but such approaches\nrequire access to a true free energy functional; one that evaluates to the\nequilibrium electrostatic energy at its minimum. In this letter, we derive the\nneeded functional. As an application, we develop a Car-Parrinello MD method for\nthe simulation of free charges present near a spherical emulsion droplet\nseparating two immiscible liquids with different dielectric constants. Our\nresults show the presence of non-monotonic ionic profiles in the dielectric\nwith lower dielectric constant.",
        "positive": "Anomalous Dynamics of Unbiased Polymer Translocation through a Narrow\n  Pore: We consider a polymer of length $N$ translocating through a narrow pore in\nthe absence of external fields. Characterization of its purportedly anomalous\ndynamics has so far remained incomplete. We show that the polymer dynamics is\nanomalous until the Rouse time $\\tau_{R}\\sim N^{1+2\\nu}$, with a mean square\ndisplacement through the pore consistent with $t^{(1+\\nu)/(1+2\\nu)}$, with\n$\\nu\\approx0.588$ the Flory exponent. This is shown to be directly related to a\ndecay in time of the excess monomer density near the pore as\n$t^{-(1+\\nu)/(1+2\\nu)}\\exp(-t/\\tau_{R})$. Beyond the Rouse time translocation\nbecomes diffusive. In consequence of this, the dwell-time $\\tau_{d}$, the time\na translocating polymer typically spends within the pore, scales as\n$N^{2+\\nu}$, in contrast to previous claims."
    },
    {
        "anchor": "Probing active nematics with in-situ microfabricated elastic inclusions: In this work, we report a direct measurement of the forces exerted by a\ntubulin/kinesin active nematic gel as well as its complete rheological\ncharacterization, including the quantification of its shear viscosity, {\\eta},\nand its activity parameter, {\\alpha}. For this, we develop a novel method that\nallows us to rapidly photo-polymerize compliant elastic inclusions in the\ncontinuously remodelling active system. Moreover, we quantitatively settle\nlong-standing theoretical predictions, such as a postulated relationship\nencoding the intrinsic time scale of the active nematic in terms of {\\eta} and\n{\\alpha}. In parallel, we infer a value for the nematic elasticity constant, K,\nby combining our measurements with the theorized scaling of the active length\nscale. On top of the microrheology capatilities, we demonstrate novel\nstrategies for defect encapsulation, quantification of defect mechanics, and\ndefect interactions, enabled by the versatility of the new microfabrication\nstrategy that allows to combine elastic motifs of different shape and stiffness\nthat are fabricated in-situ and on-time.",
        "positive": "Reduction in Tension and Stiffening of Lipid Membranes in an Electric\n  Field Revealed by X-ray Scattering: The effect of AC electric fields on the elasticity of supported lipid\nbilayers has been investigated at the microscopic level using grazing incidence\nsynchrotron x-ray scattering. A strong decrease in the membrane tension up to\n1mN/m and a dramatic increase of its effective rigidity up to 300kBT are\nobserved for local electric potentials seen by the membrane < 1V. The\nexperimental results were analyzed using detailed electrokinetic modeling and\nnon-linear Poisson-Boltzmann theory. Based on a modeling of the electromagnetic\nstress which provides an accurate description of bilayer separation vs pressure\ncurves, we show that the decrease in tension results from the amplification of\ncharge fluctuations on the membrane surface whereas the increase in bending\nrigidity results from direct interaction between charges in the electric double\nlayer. These effects eventually lead to a destabilization of the bilayer and\nvesicle formation. Similar effects are expected at the tens of nanometer\nlengthscale in cell membranes with lower tension, and could explain a number of\nelectrically driven processes."
    },
    {
        "anchor": "Two dimensional foam rheology with viscous drag: We formulate and apply a continuum model that incorporates elasticity, yield\nstress, plasticity and viscous drag. It is motivated by the two-dimensional\nfoam rheology experiments of Debregeas et al. [G. Debregeas, H. Tabuteau, and\nJ.-M. di Meglio, Phys. Rev. Lett. 87, 178305 (2001)] and Wang et al [Y. Wang,\nK. Krishan, and M. Dennin, Phys. Rev. E 73, 031401 (2006)], and is successful\nin exhibiting their principal features an exponentially decaying velocity\nprofile and strain localisation. Transient effects are also identified.",
        "positive": "Formation of a fast \"lane\" for positional transition in a\n  microparticle-suspended nematic liquid crystal cell: In this paper, based on the numerical calculation of total energy utilizing\nthe Green's function method, we found that the external electric field applied\nto a microparticle-suspended nematic liquid crystal cell, if reaching a\ncritical value, combined with its direction, surface anchoring feature and\nmolecular dielectric anisotropy, is possible to create an anisotropic \"bubble\"\naround the microparticle with a vertical fast \"lane\", in which the\nmicroparticle can, driven by the asymmetric buoyant force, vertically move\nswiftly from the cell's midplane to a new equilibrium position, triggering a\npositional transition discovered by the author previously. Such a new\nequilibrium position is decided via a competition between the buoyant force and\nthe effective force built upon the microparticle by the elastic energy gradient\nalong the \"lane\". The threshold value of external field, depends on thickness\n$L$ and Frank elastic constant $K$ and slightly on the microparticle size and\ndensity, in a Fr\\'{e}edericksz-like manner, but by a factor. For a nematic\nliquid crystal cell with planar surface alignment, a bistable equilibrium\nstructure for the transition is found when the direction of the applied\nelectric field is (a) perpendicular to the two plates of the cell with positive\nmolecular dielectric anisotropy, or (b) parallel to the two plates and the\nanchoring direction of the cell with negative molecular dielectric anisotropy.\nExcept for the formation of a vertical fast \"lane\", when the electric field\napplied is parallel to both the two plates and perpendicular to the anchoring\ndirection, the microparticle suspended in the nematic liquid crystal tends to\nbe trapped in the midplane, regardless of the sign of the molecular dielectric\nanisotropy. Such phenomenon also occurs for negative molecular dielectric\nanisotropy while the external is applied perpendicular to the two plates."
    },
    {
        "anchor": "Domain walls in vertically vibrated monolayers of cylinders confined in\n  annuli: Liquid-crystalline ordering in vertically vibrated granular monolayers\nconfined in annuli of different sizes is examined. The annuli consist of\ncircular cavities with a central circular obstruction. In the absence of the\ncentral obstruction cylinders of low aspect-ratio exhibit tetratic order,\nexcept for the existence of four defects which restore the symmetry broken by\nthe circular confinement. This behaviour is demanded by topology in systems\nwith strong anchoring properties at the surface. By contrast, topology dictates\nthat the annular geometry is compatible with a distorted tetratic phase without\npoint defects. However, the effect of restricted geometry and limited size on\nphases possessing finite anchoring energy at the wall and elastic stiffness\nleads to different configurations, showing finite ordered regions separated by\ndomain walls. We argue that highly packed nonequilibrium vibrated granular\nmonolayers respond to geometrical frustration and extreme confinement as\ncorresponding equilibrium systems of particles do, and that the former can be\nanalysed in terms of surface free energies, elastic distortions and defects,\nmuch as equilibrium liquid crystals. Therefore, selective confinement of\nvertically-vibrated monolayers of rods could be used with advantage as a new\ntool to study the creation and dynamics of various types of defects in ordered\nsystems.",
        "positive": "A confined rod: mean field theory for hard rod-like particles: In this paper, we model the configurations of a system of hard rods by\nviewing each rod in a cell formed by its neighbors. By minimizing the free\nenergy in the model and performing molecular dynamics, where, in both cases,\nthe shape of the cell is a free parameter, we obtain the equilibrium\norientational order parameter, free energy and pressure of the system. Our\nmodel enables the calculation of anisotropic stresses exerted on the walls of\nthe cell due to shape change of the rod in photoisomerization. These results\nare a key step towards understanding molecular shape change effects in\nphotomechanical systems under illumination."
    },
    {
        "anchor": "Exact axisymmetric interaction of phoretically active Janus particles: We study the axisymmetric interaction of two chemically active Janus\nparticles. By relying on the linearity of the field equations and symmetry\narguments, we derive a generic solution for the relative velocity of the\nparticles. We show that regardless of the chemical properties of the system,\nthe relative velocity can be written as a linear summation of geometrical\nfunctions which only depend on the gap size between the particles. We evaluate\nthese functions via an exact approach which accounts for the full chemical and\nhydrodynamic interactions. Using the obtained solution, we expose the role of\neach compartment in the relative motion, and also discuss the contribution of\ndifferent interactions. We then show that the dynamical system describing the\nrelative motion of two Janus particles can have up to three fixed points. These\nfixed points can be stable or unstable, indicating that a system of two Janus\nparticles can exhibit a variety of nontrivial behaviour depending on their\ninitial gap size, and their chemical properties. We also look at the specific\ncase of Janus particles in which one compartment is inert, and present regime\ndiagrams for their relative behaviour in the activity-mobility parameter space.",
        "positive": "From Microscale Variations to Macroscopic Effects: Directional\n  Actuation, Phase Transition, and Negative Compressibility in Microfiber-Based\n  Shape-Morphing Networks: Two-dimensional shape-morphing networks are common in biological systems and\nhave garnered attention due to their nontrivial physical properties that\nemanate from their cellular nature. Here, we present the fabrication and\ncharacterization of inhomogeneous shape-morphing networks composed of\nthermoresponsive microfibers. By strategically positioning fibers with varying\nresponses, we construct networks that exhibit directional actuation. The\nindividual segments within the network display either a linear extension or\nbuckling upon swelling, depending on their radius and length, and the\ntransition between these morphing behaviors resembles Landau's second-order\nphase transition. The microscale variations in morphing behaviors are\ntranslated into observable macroscopic effects, wherein regions undergoing\nlinear expansion retain their shape upon swelling, whereas buckled regions\ndemonstrate negative compressibility and shrink. Manipulating the macroscale\nmorphing by adjusting the properties of the fibrous microsegments offers a\nmeans to modulate and program morphing with mesoscale precision and unlocks\nnovel opportunities for developing programmable microscale soft robotics and\nactuators."
    },
    {
        "anchor": "Effects of Substrate Defects on Lipid Bilayer Compression Dynamics: In vivo and in vitro lipid bilayers are commonly supported by subcellular\nstructures, particles, and artificial substrates. Deformation of the underlying\nstructure can lead to large, localized deformations as the bilayer deforms to\navoid stretching. In this work, we consider the effect of defects within the\nunderlying substrate by simulating different bilayers supported by continuous\nand nanoporous substrates. We show that the bilayer behavior greatly depends on\nstrain rate, and that substrate defects may contribute to the formation of\nnanotubes for compressed substrate.",
        "positive": "Long-range fluctuation-induced forces in driven electrolytes: We study the stochastic dynamics of an electrolyte driven by a uniform\nexternal electric field and show that it exhibits generic scale invariance\ndespite the presence of Debye screening. The resulting long-range correlations\ngive rise to a Casimir-like fluctuation-induced force between neutral\nboundaries that confine the ions; this force is controlled by the external\nelectric field, and it can be both attractive and repulsive with similar\nboundary conditions, unlike other long-range fluctuation-induced forces. This\nwork highlights the importance of nonequilibrium correlations in electrolytes\nand shows how they can be used to tune interactions between uncharged\nbiological or synthetic structures at large separations."
    },
    {
        "anchor": "Imparting icephobicity with substrate flexibility: Ice accumulation hinders the performance of, and poses safety threats for\ninfrastructure both on the ground and in the air. Previously, rationally\ndesigned superhydrophobic surfaces have demonstrated some potential as a\npassive means to mitigate ice accretion; however, further studies on material\nsolutions that reduce impalement and contact time for impacting supercooled\ndroplets and can also repel droplets that freeze during surface contact are\nurgently needed. Here we demonstrate the collaborative effect of substrate\nflexibility and surface nanotexture on enhancing both icephobicity and the\nrepellency of viscous droplets. We first investigate the influence of increased\nviscosity on impalement resistance and droplet-substrate contact time after\nimpact. Then we examine the effect of droplet partial solidification on recoil\nand simulate more challenging icing conditions by impacting supercooled water\ndroplets onto flexible and rigid surfaces containing ice nucleation promoters.\nWe demonstrate a passive mechanism for shedding partially solidified droplets\nunder conditions where partial solidification occurs much faster than the\nnatural droplet oscillation which does not rely on converting droplet surface\nenergy into kinetic energy. Using an energy-based model, we identify a\npreviously unexplored mechanism whereby the substrate oscillation and velocity\ngovern the rebound process, with low-areal density and moderately stiff\nsubstrates acting to efficiently absorb the incoming droplet kinetic energy and\nrectify it back, allowing droplets to overcome adhesion and gravitational\nforces, and recoil. This mechanism applies for a range of droplet viscosities,\nspanning from low to high viscosity fluids and even ice slurries, which do not\nrebound from rigid superhydrophobic substrates.",
        "positive": "The Narrow Escape Problem of a Chiral Active Particle (CAP): An Optimal\n  Scheme: We report a simulation study on the narrow escape kinetics of a Chiral Active\nParticle (CAP) confined to a circular domain with a narrow escape opening. The\nstudys main objective is to optimize the CAPs escape changes as a function of\nthe relevant parameters, such as translational and rotational speeds of the\nCAP, domain size, etc. We identified three regimes in the escape kinetics,\nnamely the noise-dominated regime, the optimal regime, and the chiral\nactivity-dominated regime. In particular, the optimal regime is characterized\nby an escape scheme that involves a direct passage to the domain boundary first\nand then a unidirectional drift along the boundary towards the exit.\nFurthermore, we propose a non-dimensionalization approach to optimize the\nescape performance across microorganisms with varying motile characteristics.\nAdditionally, we explore the influence of the translational and rotational\nnoise on the CAPs escape kinetics"
    },
    {
        "anchor": "Shear-wave-induced softening and simultaneous compaction in dense\n  granular media through acoustic lubrication at flow heterogeneities: We report the simultaneous softening and compaction of a confined dense\ngranular pack in acoustic resonance experiments. Elastic softening is\nmanifested by a reduction of the shear-wave speed, as the wave amplitude\nincreases beyond some threshold. No macroscopic rearrangement of grains or\ndilatancy is observed; instead, elastic softening is accompanied by a tiny\namount of compaction on the scale of grain asperities. We explain these\napparent contradictory observations using a theoretical model, based on shear\ntransformation zones (STZs), of soft spots and slipping contacts. It predicts a\nlinear shear stress-strain response with negligible macro-plastic deformation\ndue to the small-amplitude acoustic oscillation. However, these waves reduce\nthe interparticle friction and contact stiffness through the acoustic\nlubrication of grain contacts, resulting in an increase in the structural\ndisorder or compactivity and softening of dynamic modulus. The compaction\nassociated with this microscopic friction decrease is consistent with the\nprediction by an Ising-like correlation between STZs in the subyield regime.",
        "positive": "Transport of Forced Quantum Motors in the Strong Friction Limit: The directed transport of an overdamped Brownian motor moving in a spatially\nperiodic potential that lacks reflection symmetry (i.e. a ratchet potential) is\nstudied when driven by thermal and dichotomic nonequilibrium noise in the\npresence of an external, constant load force. We consider both, the classical\nand the quantum tunneling assisted regimes. The current-load characteristics\nare investigated as a function of the system parameters like the load force,\nthe temperature and the amplitude strength of the applied two-state noise."
    },
    {
        "anchor": "Direct measurements of growing amorphous order and non-monotonic dynamic\n  correlations in a colloidal glass-former: While the transformation of flowing liquids into rigid glasses is\nomnipresent, a complete understanding of vitrification remains elusive. Of the\nnumerous approaches aimed at solving the glass transition problem, the Random\nFirst-Order Theory (RFOT) is the most prominent. However, the existence of the\nunderlying thermodynamic phase transition envisioned by RFOT remains debatable,\nsince its key microscopic predictions concerning the growth of amorphous order\nand the nature of dynamic correlations lack experimental verification. Here, by\nusing holographic optical tweezers, we freeze a wall of particles in an\nequilibrium configuration of a 2D colloidal glass-forming liquid and provide\ndirect evidence for growing amorphous order in the form of a static\npoint-to-set length. Most remarkably, we uncover the non-monotonic dependence\nof dynamic correlations on area fraction and show that this non-monotonicity\nfollows directly from the change in morphology of cooperatively rearranging\nregions, as predicted by RFOT. Our findings suggest that the glass transition\nhas a thermodynamic origin.",
        "positive": "Biaxial Deformations of Rubber: Entanglements or Elastic Fluctuations?: The classical theory of rubber elasticity fails in the regime of large\ndeformation. The un- derlying physical mechanism has been under debate for long\ntime. In this work, we test the recently proposed mechanism of thermal elastic\nfluctuations by Xing, Goldbart and Radzi- hovsky1 against the biaxial\nstress-strain data of three distinct polymer networks with very different\nnetwork structures, synthesized by Urayama2 and Kawabata3 respectively. We find\nthat both the two parameters version and the one-parameter version of the XGR\ntheory provide satisfactory description of the elasticity in whole deformation\nrange. For comparison, we also fit the same sets of data using the slip-link\nmodel by Edwards and Vilgis with four parameters. The fitting qualities of two\ntheories are found to be comparable."
    },
    {
        "anchor": "Dynamics of a grain-scale intruder in a two-dimensional granular medium\n  with and without basal friction: We report on a series of experiments in which a grain-sized intruder is\npushed by a spring through a 2D granular material comprised of photoelastic\ndisks in a Couette geometry. We study the intruder dynamics as a function of\npacking fraction for two types of supporting substrates: a frictional glass\nplate and a layer of water for which basal friction forces are negligible. We\nobserve two dynamical regimes: intermittent flow, in which the intruder moves\nfreely most of the time but occasionally gets stuck, and stick-slip dynamics,\nin which the intruder advances via a sequence of distinct, rapid events. When\nbasal friction is present, we observe a smooth crossover between the two\nregimes as a function of packing fraction, and we find that reducing the\ninterparticle friction coefficient causes the stick-slip regime to shift to\nhigher packing fractions. When basal friction is eliminated, we observe\nintermittent flow at all accessible packing fractions. For all cases, we\npresent results for the statistics of stick events, the intruder velocity, and\nthe force exerted on the intruder by the grains. Our results indicate the\nqualitative importance of basal friction at high packing fractions and suggest\na possible connection between intruder dynamics in a static material and\nclogging dynamics in granular flows.",
        "positive": "The Implications of Grain Size Variation in Magnetic Field Alignment of\n  Block Copolymer Blends: Recent experiments have highlighted the intrinsic magnetic anisotropy in\ncoil-coil diblock copolymers, specifically in poly(styrene-b-4-vinylpyridine)\n(PS-b-P4VP), that enables magnetic field alignment at field strengths of a few\ntesla. We consider here the alignment response of two low molecular weight (MW)\nlamallae-forming PS-b-P4VP systems. Cooling across the disorder-order\ntransition temperature ($\\mathrm{T_{odt}}$) results in strong alignment for the\nhigher MW sample (5.5K), whereas little alignment is discernible for the lower\nMW system (3.6K). This disparity under otherwise identical conditions of field\nstrength and cooling rate suggests that different average grain sizes are\nproduced during slow cooling of these materials, with larger grains formed in\nthe higher MW material. Blending the block copolymers results in homogeneous\nsamples which display $\\mathrm{T_{odt}}$, d-spacings and grain sizes that are\nintermediate between the two neat diblocks. Similarly, the alignment quality\ndisplays a smooth variation with the concentration of the higher MW diblock in\nthe blends and the size of grains likewise interpolates between limits set by\nthe neat diblocks, with a factor of 3.5X difference in the grain size observed\nin high vs low MW neat diblocks. These results highlight the importance of\ngrain growth kinetics in dictating the field response in block copolymers and\nsuggests an unconventional route for the manipulation of such kinetics."
    },
    {
        "anchor": "Colloidal hydrodynamic coupling in concentric optical vortices: Optical vortex traps created from helical modes of light can drive\nfluid-borne colloidal particles in circular trajectories. Concentric\ncirculating rings of particles formed by coaxial optical vortices form a\nmicroscopic Couette cell, in which the amount of hydrodynamic drag experienced\nby the spheres depends on the relative sense of the rings' circulation.\nTracking the particles' motions makes possible measurements of the hydrodynamic\ncoupling between the circular particle trains and addresses recently proposed\nhydrodynamic instabilities for collective colloidal motions on optical\nvortices.",
        "positive": "Dual-Guest Functionalised ZIF-8 Framework for 3D Printing White\n  Light-Emitting Composites: Metal-organic frameworks (MOFs) stand as a promising chemically-active host\nscaffold for the encapsulation of functional guests, because they could enhance\nluminescent properties by molecular separation of fluorophores in the nanoscale\npores of the MOF crystals. Herein, we show simultaneous nanoconfinement of two\nfluorophores viz. (A) Fluorescein and (B) Rhodamine B in the sodalite cages of\nZIF-8, constructed under ambient conditions through a simple one-pot reaction.\nWe report a novel dual-guest@MOF system, termed: A+B@ZIF-8, which overcomes the\nintrinsic problem of aggregation caused quenching in the solid-state to gain\nbright yellow emission under UV irradiation. Subsequently, we combine this\nyellow emitter with a blue-emitting photopolymer resin, to yield a 3D printable\nluminescent composite material. We design a number of 3D printable composite\nobjects for converting UV into warm white light emission, achieving a high\nquantum yield of ~44% in the solid-state 3D printed form. This research\ninstigates the bespoke application of a vast range of 3D printable Guest@MOF\ndesigner composites targeting energy-saving lighting devices, smart sensors and\nfuture optoelectronics."
    },
    {
        "anchor": "NMR for Equilateral Triangular Geometry under Conditions of Surface\n  Relaxivity - Analytical and Random Walk Solution: We consider analytical and numerical solution of NMR relaxation under the\ncondition of surface relaxation in an equilateral triangular geometry. We\npresent an analytical expression for the Green's function in this geometry. We\ncalculate the transverse magnetic relaxation without magnetic gradients\npresent, single-phase, both analytically and numerically. There is a very good\nmatch between the analytical and numerical results. We also show that the\nmagnetic signal from an equilateral triangular geometry is qualitatively\ndifferent from the known solution: plate, cylinder and sphere, in the case of a\nnonuniform initial magnetization. Non uniform magnetization close to the sharp\ncorners makes the magnetic signal very fast multi exponential. This type of\ninitial configuration fits qualitatively with the experimental results by Song\net al.[1]. It should also be noted that the solution presented here can be used\nto describe absorption of a chemical substance in an equilateral triangular\ngeometry (for a stationary fluid).",
        "positive": "Intermittent Attractive Interactions Lead to Microphase Separation in\n  Non-motile Active Matter: Non-motile active matter exhibits a wide range of non-equilibrium collective\nphenomena yet examples are crucially lacking in the literature. We present a\nmicroscopic model inspired by the bacteria {\\it Neisseria Meningitidis} in\nwhich diffusive agents feel intermittent attractive forces. Through a formal\ncoarse-graining procedure, we show that this truly scalar model of active\nmatter exhibits the time-reversal-symmetry breaking terms defining the {\\it\nActive Model B+} class. In particular, we confirm the presence of microphase\nseparation by solving the kinetic equations numerically. We show that the\nswitching rate controlling the interactions provides a regulation mechanism\ntuning the typical cluster size, e.g. in populations of bacteria interacting\nvia type IV pili."
    },
    {
        "anchor": "Optimisation of a Brownian dynamics algorithm for semidilute polymer\n  solutions: Simulating the static and dynamic properties of semidilute polymer solutions\nwith Brownian dynamics (BD) requires the computation of a large system of\npolymer chains coupled to one another through excluded-volume and hydrodynamic\ninteractions. In the presence of periodic boundary conditions, long-ranged\nhydrodynamic interactions are frequently summed with the Ewald summation\ntechnique. By performing detailed simulations that shed light on the influence\nof several tuning parameters involved both in the Ewald summation method, and\nin the efficient treatment of Brownian forces, we develop a BD algorithm in\nwhich the computational cost scales as O(N^{1.8}), where N is the number of\nmonomers in the simulation box. We show that Beenakker's original\nimplementation of the Ewald sum, which is only valid for systems without bead\noverlap, can be modified so that \\theta-solutions can be simulated by switching\noff excluded-volume interactions. A comparison of the predictions of the radius\nof gyration, the end-to-end vector, and the self-diffusion coefficient by BD,\nat a range of concentrations, with the hybrid Lattice Boltzmann/Molecular\nDynamics (LB/MD) method shows excellent agreement between the two methods. In\ncontrast to the situation for dilute solutions, the LB/MD method is shown to be\nsignificantly more computationally efficient than the current implementation of\nBD for simulating semidilute solutions. We argue however that further\noptimisations should be possible.",
        "positive": "Elasticity of spheres with buckled surfaces: The buckling instabilities of core-shell systems, comprising an interior\nelastic sphere, attached to an exterior shell, have been proposed to underlie\nmyriad biological morphologies. To fully discuss such systems, however, it is\nimportant to properly understand the elasticity of the spherical core. Here, by\nexploiting well-known properties of the solid harmonics, we present a simple,\ndirect method for solving the linear elastic problem of spheres and spherical\nvoids with surface deformations, described by a real spherical harmonic. We\ncalculate the corresponding bulk elastic energies, providing closed-form\nexpressions for any values of the spherical harmonic degree (l), Poisson ratio,\nand shear modulus. We find that the elastic energies are independent of the\nspherical harmonic index (m). Using these results, we revisit the buckling\ninstability experienced by a core-shell system comprising an elastic sphere,\nattached within a membrane of fixed area, that occurs when the area of the\nmembrane sufficiently exceeds the area of the unstrained sphere [C. Fogle, A.\nC. Rowat, A. J. Levine and J. Rudnick, Phys. Rev. E 88, 052404 (2013)]. We\ndetermine the phase diagram of the core-shell sphere's shape, specifying what\nvalue of l is realized as a function of the area mismatch and the core-shell\nelasticity. We also determine the shape phase diagram for a spherical void\nbounded by a fixed-area membrane."
    },
    {
        "anchor": "Normal modes analysis of the microscopic dynamics in hard discs: We estimate numerically the normal modes of the free energy in a glass of\nhard discs. We observe that, near the glass transition or after a rapid quench\ndeep in the glass phase, the density of states (i) is characteristic of a\nmarginally stable structure, in particular it di splays a frequency scale\n$\\omega^*\\sim p^{1/2}$, where $p$ is the pressure and (ii) gives a faithful\nrepresentation of the short-time dyn amics. This brings further evidences that\nthe boson peak near the glass transition corresponds to the relaxation of\nmarginal modes of a we akly-coordinated structure, and implies that the mean\nsquare displacement in the glass phase is anomalously large and goes as $<\n\\delta R^2 > \\sim p^{-3/2}$, a prediction that we check numerically.",
        "positive": "Focusing and sorting of ellipsoidal magnetic particles in microchannels: We present a simple method to control the position of ellipsoidal magnetic\nparticles in microchannel Poiseuille flow using a static uniform magnetic\nfield. The magnetic field is utilized to pin the particle orientation, and the\nhydrodynamic interactions between ellipsoids and channel walls allow control of\nthe transverse position of the particles. We employ a far-field hydrodynamic\ntheory and simulations using the boundary element method and Brownian dynamics\nto show how magnetic particles can be focussed and segregated by size and\nshape. This is of importance for particle manipulation in lab-on-a-chip\ndevices."
    },
    {
        "anchor": "A Brownian dynamics algorithm for entangled wormlike threads: We present a hybrid Brownian dynamics / Monte Carlo algorithm for simulating\nsolutions of highly entangled semiflexible polymers or filaments. The algorithm\ncombines a Brownian dynamics time-stepping approach with an efficient scheme\nfor rejecting moves that cause chains to cross or that lead to excluded volume\noverlaps. The algorithm allows simulation of the limit of infinitely thin but\nuncrossable threads, and is suitable for simulating the conditions obtained in\nexperiments on solutions of long actin protein filaments.",
        "positive": "Model plasma membrane indicates the inner leaflet is poised to initiate\n  compositional heterogeneities: We investigate a model of an asymmetric bilayer consisting of sphigomyelin,\nphosphatidylcholine, and cholesterol in the outer leaflet, and\nphosphatidyl\\-ethanolamine, (PE), phosphatidylserine, and cholesterol in the\ninner leaflet. Composition fluctuations are coupled to membrane fluctuations\nvia the bending energy which depends upon the local spontaneous curvature\ndominated by the PE in the inner leaflet. This brings about a microemulsion in\nthat leaflet with a characteristic wavelength of 37 nm as shown by the PE-PE\nstructure function. Thus the inner leaflet will respond to an external\nperturbation most strongly at this length. However the correlation length is\napproximately 1 nm so that composition variations are not seen in the inner\nleaflet itself. Depending upon the strength of the coupling between leaflets,\nthe outer leaflet is either a normal fluid or is also a microemulsion. In this\nmodel then, the lipids of the plasma membrane would not evince inhomogeneities,\nbut would be primed to create them from the inner leaflet in response to\nnon-lipid perturbations."
    },
    {
        "anchor": "Molecular ordering in lipid monolayers: an atomistic simulation: We report on atomistic simulations of DPPC lipid monolayers using the\nCHARMM36 lipid force field and four-point OPC water model. The entire two-phase\nregion where domains of the `liquid-condensed' (LC) phase coexist with domains\nof the `liquid-expanded' (LE) phase has been explored. The simulations are long\nenough that the complete phase-transition stage, with two domains coexisting in\nthe monolayer, is reached in all cases. Also, system sizes used are larger than\nin previous works. As expected, domains of the minority phase are elongated,\nemphasizing the importance of anisotropic van der Waals and/or electrostatic\ndipolar interactions in the monolayer plane. The molecular structure is\nquantified in terms of distribution functions for the hydrocarbon chains and\nthe PN dipoles. In contrast to previous work, where average distributions are\ncalculated, distributions are here extracted for each of the coexisting phases\nby first identifying lipid molecules that belong to either LC or LE regions.\nThe three-dimensional distributions show that the average tilt angle of the\nchains with respect to the normal outward direction is $(39.0\\pm 0.1)^{\\circ}$\nin the LC phase. % and $(48.1\\pm 0.5)^{\\circ}$ in the LC phase. In the case of\nthe PN dipoles the distributions indicate a tilt angle of $(110.8\\pm\n0.5)^{\\circ}$ in the LC phase and $(112.5\\pm 0.5)^{\\circ}$ in the LE phase.\nThese results are quantitatively different from previous works, which indicated\na smaller normal component of the PN dipole. Also, the distributions of the\nmonolayer-projected chains and PN dipoles have been calculated. Chain\ndistributions peak along a particular direction in the LC domains, while they\nare uniform in the LE phase. Long-range ordering associated with the projected\nPN dipoles is absent in both phases.",
        "positive": "Emergent states in dense systems of active rods: from swarming to\n  turbulence: Dense suspensions of self-propelled rod-like particles exhibit a fascinating\nvariety of non-equilibrium phenomena. By means of computer simulations of a\nminimal model for rigid self-propelled colloidal rods with variable shape we\nexplore the generic diagram of emerging states over a large range of rod\ndensities and aspect ratios. The dynamics is studied using a simple numerical\nscheme for the overdamped noiseless frictional dynamics of a many-body system\nin which steric forces are dominant over hydrodynamic ones. The different\nemergent states are identified by various characteristic correlation functions\nand suitable order parameter fields. At low density and aspect ratio, a\ndisordered phase with no coherent motion precedes a highly-cooperative swarming\nstate at large aspect ratio. Conversely, at high densities weakly anisometric\nparticles show a distinct jamming transition whereas slender particles form\ndynamic laning patterns. In between there is a large window corresponding to\nstrongly vortical, turbulent flow. The different dynamical states should be\nverifiable in systems of swimming bacteria and artificial rod-like\nmicro-swimmers."
    },
    {
        "anchor": "Phase Diagrams of Binary Mixtures of Oppositely Charged Colloids: Phase diagrams of binary mixtures of oppositely charged colloids are\ncalculated theoretically. The proposed mean-field-like formalism interpolates\nbetween the limits of a hard-sphere system at high temperatures and the\ncolloidal crystals which minimize Madelung-like energy sums at low\ntemperatures. Comparison with computer simulations of an equimolar mixture of\noppositely charged, equally sized spheres indicate semi-quantitative accuracy\nof the proposed formalism. We calculate global phase diagrams of binary\nmixtures of equally sized spheres with opposite charges and equal charge\nmagnitude in terms of temperature, pressure, and composition. The influence of\nthe screening of the Coulomb interaction upon the topology of the phase diagram\nis discussed. Insight into the topology of the global phase diagram as a\nfunction of the system parameters leads to predictions on the preparation\nconditions for specific binary colloidal crystals.",
        "positive": "Dynamics of Polydisperse Polymer Mixtures: We develop a general analysis of the diffusive dynamics of polydisperse\npolymers in the presence of chemical potential gradients, within the context of\nthe tube model (with all species entangled). We obtain a set of coupled\ndynamical equations for the time evolution of the polymeric densities with\nexplicitly derived coefficients. For the case of chemical polydispersity (a set\nof chains that are identical except for having a continuous spectrum of\nenthalpic interaction strengths) the coupled equations can be fully solved in\ncertain cases. For these we study the linearised mode spectrum following a\nquench through the spinodal, with and without a passive (polymeric) solvent. We\nalso study the more conventional case of length polydisperse chains in a poor\nsolvent."
    },
    {
        "anchor": "Xe films on a decagonal Al-Ni-Co quasicrystal surface: The grand canonical Monte Carlo method is employed to study the adsorption of\nXe on a quasicrystalline Al-Ni-Co surface. The calculation uses a semiempirical\ngas-surface interaction, based on conventional combining rules and the usual\nLennard-Jones Xe-Xe interaction. The resulting adsorption isotherms and\ncalculated structures are consistent with the results of LEED experimental\ndata. In this paper we focus on five features not discussed earlier (Phys. Rev.\nLett. 95, 136104 (2005)): the range of the average density of the adsorbate,\nthe order of the transition, the orientational degeneracy of the ground state,\nthe isosteric heat of adsorption of the system, and the effect of the vertical\ncell dimension.",
        "positive": "Photoferroelectric solar to electrical conversion: We propose a charge pump which converts solar energy into DC electricity. It\nis based on cyclic changes in the spontaneous electric polarization of a\nphotoferroelectric material, which allows a transfer of charge from a low to a\nhigh voltage. To estimate the power efficiency we use a photoferroelectric\nliquid crystal as the working substance. For a specific choice of material, an\nefficiency of $2\\%$ is obtained."
    },
    {
        "anchor": "Unzipping of DNA with correlated base-sequence: We consider force-induced unzipping transition for a heterogeneous DNA model\nwith a correlated base-sequence. Both finite-range and long-range correlated\nsituations are considered. It is shown that finite-range correlations increase\nstability of DNA with respect to the external unzipping force. Due to\nlong-range correlations the number of unzipped base-pairs displays two widely\ndifferent scenarios depending on the details of the base-sequence: either there\nis no unzipping phase-transition at all, or the transition is realized via a\nsequence of jumps with magnitude comparable to the size of the system. Both\nscenarios are different from the behavior of the average number of unzipped\nbase-pairs (non-self-averaging). The results can be relevant for explaining the\nbiological purpose of correlated structures in DNA.",
        "positive": "Rigidity Loss in Disordered Systems: Three Scenarios: We reveal significant qualitative differences in the rigidity transition of\nthree types of disordered network materials: randomly diluted spring networks,\njammed sphere packings, and stress-relieved networks that are diluted using a\nprotocol that avoids the appearance of floppy regions. The marginal state of\njammed and stress-relieved networks are globally isostatic, while marginal\nrandomly diluted networks show both overconstrained and underconstrained\nregions. When a single bond is added to or removed from these isostatic\nsystems, jammed networks become globally overconstrained or floppy, whereas the\neffect on stress-relieved networks is more local and limited. These differences\nare also reflected in the linear elastic properties and point to the highly\neffective and unusual role of global self-organization in jammed sphere\npackings."
    },
    {
        "anchor": "Logarithmic decay in single-particle relaxations of hydrated lysozyme\n  powder: We present the self-dynamics of protein amino acids of hydrated lysozyme\npowder around the physiological temperature by means of molecular dynamics (MD)\nsimulations. The self-intermediate scattering functions (SISF) of the amino\nacid residue center-of-mass and of the protein hydrogen atoms display a\nlogarithmic decay over 3 decades of time, from 2 picoseconds to 2 nanoseconds,\nfollowed by an exponential alpha-relaxation. This kind of slow dynamics\nresembles the relaxation scenario within the beta-relaxation time range\npredicted by the mode coupling theory (MCT) in the vicinity of higher-order\nsingularities. These results suggest a strong analogy between the\nsingle-particle dynamics of the protein and the dynamics of colloidal,\npolymeric and molecular glass-forming liquids.",
        "positive": "An Empirical Correction for Moderate Multiple Scattering in\n  Super-Heterodyne Light Scattering: Frequency domain super-heterodyne laser light scattering is utilized in a low\nangle integral measurement configuration to determine flow and diffusion in\ncharged sphere suspensions showing moderate to strong multiple scattering. We\nintroduce an empirical correction to subtract the multiple scattering\nbackground and isolate the singly scattered light. We demonstrate the excellent\nfeasibility of this simple approach for turbid suspensions of transmittance\nT>0.4. We study the particle concentration dependence of the electro-kinetic\nmobility in low salt aqueous suspension over an extended concentration regime\nand observe a maximum at intermediate concentrations. We further use our scheme\nfor measurements of the self-diffusion coefficients in the fluid samples in the\nabsence or presence of shear, as well as in polycrystalline samples during\ncrystallization and coarsening. We discuss the scope and limits of our approach\nas well as possible future applications."
    },
    {
        "anchor": "A simple Discrete-Element-Model of Brazilian Test: We present a statistical model which is able to capture some interesting\nfeatures exhibited in the Brazilian test. The model is based on breakable\nelements which break when the force experienced by the elements exceed their\nown load capacity. In this model when an element breaks, the capacity of the\nneighboring elements are decreased by a certain amount assuming weakening\neffect around the defected zone. We numerically investigate the stress-strain\nbehavior, the strength of the system, how it scales with the system size and\nalso it's fluctuation for both uniformly and weibull distributed breaking\nthreshold of the elements in the system. We find that the strength of the\nsystem approaches it's asymptotic value $\\sigma_c=1/6$ and $\\sigma_c=5/18$ for\nuniformly and Weibull distributed breaking threshold of the elements\nrespectively. We have also shown the damage profile right at the point when the\nstress-strain curve reaches at it's maximum and then it is compared with our\nexperimental observations.",
        "positive": "Sequential tasks performed by catalytic pumps for colloidal\n  crystallization: Gold-platinum catalytic pumps immersed in a chemical fuel are used to\nmanipulate silica colloids. The manipulation relies on the electric field and\nthe fluid flow generated by the pump. Catalytic pumps perform various tasks,\nsuch as the repulsion of colloids, the attraction of colloids, and the guided\ncrystallization of colloids. We demonstrate that catalytic pumps can execute\nthese tasks sequentially over time. Switching from one task to the next is\nrelated to the local change of the proton concentration, which modifies the\ncolloid zeta potential and consequently the electric force acting on the\ncolloids."
    },
    {
        "anchor": "Microscopic theory for nonequilibrium correlation functions in dense\n  active fluids: One of the key hallmarks of dense active matter in the liquid, supercooled,\nand solid phases is so-called equal-time velocity correlations. Crucially,\nthese correlations can emerge spontaneously, i.e., they require no explicit\nalignment interactions, and therefore represent a generic feature of dense\nactive matter. This indicates that for a meaningful comparison or possible\nmapping between active and passive liquids one not only needs to understand\ntheir structural properties, but also the impact of these velocity\ncorrelations. This has already prompted several simulation and theoretical\nstudies, though they are mostly focused on athermal systems and thus overlook\nthe effect of translational diffusion. Here we present a fully microscopic\nmethod to calculate nonequilibrium correlations in systems of thermal active\nBrownian particles (ABPs). We use the integration through transients (ITT)\nformalism together with (active) mode-coupling theory (MCT) and analytically\ncalculate qualitatively consistent static structure factors and active velocity\ncorrelations. We complement our theoretical results with simulations of both\nthermal and athermal ABPs which exemplify the disruptive role that thermal\nnoise has on velocity correlations.",
        "positive": "(A note on) self-similarity in granular media: It is shown that the phenomenon of self-similarity appears in granular media,\nwith an intergrain potential $V \\propto \\delta^{p+1}$, $p > 1$, where $\\delta$\nis the overlap between the grains. Although this fact can be traced back in the\nliterature, this has not been put explicitly."
    },
    {
        "anchor": "Slow dynamics in a primitive tetrahedral network model: We report extensive Monte Carlo and event-driven molecular dynamics\nsimulations of the fluid and liquid phase of a primitive model for silica\nrecently introduced by Ford, Auerbach and Monson [J. Chem. Phys. 17, 8415\n(2004)]. We evaluate the iso-diffusivity lines in the temperature-density plane\nto provide an indication of the shape of the glass transition line. Except for\nlarge densities, arrest is driven by the onset of the tetrahedral bonding\npattern and the resulting dynamics is strong in the Angell's classification\nscheme. We compare structural and dynamic properties with corresponding results\nof two recently studied primitive models of network forming liquids -- a\nprimitive model for water and a angular-constraint free model of\nfour-coordinated particles -- to pin down the role of the geometric constraints\nassociated to the bonding. Eventually we discuss the similarities between\n\"glass\" formation in network forming liquids and \"gel\" formation in colloidal\ndispersions of patchy particles.",
        "positive": "Tensile elasticity of semiflexible polymers with hinge defects: It has become clear in recent years that the simple uniform wormlike chain\nmodel needs to be modified in order to account for more complex behavior which\nhas been observed experimentally in some important biopolymers. For example,\nthe large flexibility of short ds-DNA has been attributed to kink or hinge\ndefects. In this paper, we calculate analytically, within the weak bending\napproximation, the force-extension relation of a wormlike chain with a\npermanent hinge defect along its contour. The defect is characterized by its\nbending energy (which can be zero, in the completely flexible case) and its\nposition along the polymer contour. Besides the bending rigidity of the chain,\nthese are the only parameters which describe our model. We show that a hinge\ndefect causes a significant increase in the differential tensile compliance of\na pre-stressed chain. In the small force limit, a hinge defect significantly\nincreases the entropic elasticity. Our results apply to any pair of\nsemiflexible segments connected by a hinge. As such, they may also be relevant\nto cytoskeletal filaments (F-actin, microtubules), where one may treat the\ncross-link connecting two filaments as a hinge defect."
    },
    {
        "anchor": "Liquid Nanodroplets Spreading on Chemically Patterned Surfaces: Controlling the spatial distribution of liquid droplets on surfaces via\nsurface energy patterning can be used to control material delivery to specified\nregions via selective liquid/solid wetting. While studies of the equilibrium\nshape of liquid droplets on heterogenous substrates exist, much less is known\nabout the corresponding wetting kinetics. We make significant progress towards\nelucidating details of this topic by studying, via large-scale atomistic\nsimulations, liquid nanodroplets spreading on chemically patterned surfaces. A\nmodel is presented for lines of polymer liquid (droplets) on substrates\nconsisting of alternating strips of wetting (equilibrium contact angle\napproximately 0 degrees) and non-wetting (equilibrium contact angle\napproximately 90 degrees) material. Droplet spreading is compared for different\nwavelength of the pattern and strength of surface interaction on the wetting\nstrips. For small wavelength, droplets partially spread on both the wetting and\nnon-wetting regions of the substrate to attain a finite contact angle less than\n90 degrees. In this case, the extent of spreading depends on the interaction\nstrength in the wetting regions. A transition is observed such that, for large\nwavelength, the droplet spreads only on the wetting region of the substrate by\npulling material from non-wetting regions. In most cases, a precursor film\nspreads on the wetting portion of the substrate at a rate strongly dependent\nupon interaction strength.",
        "positive": "Dynamic Behaviors of Supersonic Granular Media under Vertical Vibration: We present experimental study of vibrofluidized granular materials by high\nspeed photography. Statistical results present the averaged dynamic behaviors\nof granular materials in one cycle, including the variations of height,\nvelocity and mechanical energy of the center of mass. Furthermore, time-space\ndistribution of granular temperature which corresponds to the random kinetic\nenergy shows that a temperature peak forms in the compression period and\npropagates upward with a steepened front. The Mach number in the steepened\nfront is found to be greater than unity, indicating a shock propagating in the\nsupersonic granular media."
    },
    {
        "anchor": "Fluids with competing interactions: I. Decoding the structure factor to\n  detect and characterize self-limited clustering: We use liquid state theory and computer simulations to gain insights into the\nshape of the structure factor for fluids of particles interacting via a\ncombination of short-range attractions and long-range repulsions. Such systems\ncan reversibly morph between homogeneous phases and states comprising compact\nself-limiting clusters. We first highlight trends with respect to the presence\nand location of the intermediate-range order (IRO) pre-peak in the structure\nfactor, which is commonly associated with clustering, for wide ranges of the\ntunable parameters that control interparticle interactions (e.g., Debye\nscreening length). Next, for approximately 100 different cluster phases at\nvarious conditions (where aggregates range in size from six to sixty monomers),\nwe quantitatively relate the shape of the structure factor to physical\ncharacteristics including intercluster distance and cluster size. We also test\ntwo previously postulated criteria for identifying the emergence of clustered\nphases that are based on IRO peak-height and -width, respectively. We find that\nthe criterion based on peak-width, which encodes the IRO thermal correlation\nlength, is more robust across a wide range of conditions and interaction\nstrengths but nonetheless approximate. Ultimately, we recommend a hybrid\nheuristic drawing on both pre-peak height and width for positively identifying\nthe emergence of clustered states.",
        "positive": "Critical Thickness in Dewetting Films: We study dewetting of thin polymer films with built-in topographical\nfluctuations produced by rubbing the film surface with a rayon cloth. By\nvarying the density of imposed surface defects, we unambiguously distinguish\nspinodal dewetting, which dominates in liquid films thinner than a\ncharacteristic thickness = 13.3 nm, from heterogeneous nucleation in the\nthicker films. Invariance of this characteristic thickness upon more than a\ndecade change in the defect density makes kinetic effect an unseemly origin. A\ncrossover of the spinodal line provides a consistent picture. This\ninterpretation, however, contends the current understanding of molecular\ninteractions in apolar liquid films."
    },
    {
        "anchor": "Sliding Phases in XY-Models, Crystals, and Cationic Lipid-DNA Complexes: We predict the existence of a totally new class of phases in weakly coupled,\nthree-dimensional stacks of two-dimensional (2D) XY-models. These ``sliding\nphases'' behave essentially like decoupled, independent 2D XY-models with\nprecisely zero free energy cost associated with rotating spins in one layer\nrelative to those in neighboring layers. As a result, the two-point spin\ncorrelation function decays algebraically with in-plane separation. Our\nresults, which contradict past studies because we include higher-gradient\ncouplings between layers, also apply to crystals and may explain recently\nobserved behavior in cationic lipid-DNA complexes.",
        "positive": "Bridging transitions for spheres and cylinders: We study bridging transitions between spherically and cylindrically shaped\nparticles (colloids) of radius $R$ separated by a distance $H$ that are\ndissolved in a bulk fluid (solvent). Using macroscopics, microscopic density\nfunctional theory and finite-size scaling theory we study the location and\norder of the bridging transition and also the stability of the liquid bridges\nwhich determines spinodal lines. The location of the bridging transitions is\nsimilar for cylinders and spheres, so that for example, at bulk coexistence the\ndistance $H_b$ at which a transition between bridged and unbridged\nconfigurations occurs, is proportional to the colloid radius $R$. However all\nother aspects, and, in particular, the stability of liquid bridges, are very\ndifferent in the two systems. Thus, for cylinders the bridging transition is\ntypically strongly first-order, while for spheres it may be first-order,\ncritical or rounded as determined by a critical radius $R_c$. The influence of\nthick wetting films and fluctuation effects beyond mean-field are also\ndiscussed in depth."
    },
    {
        "anchor": "Fitting multiple small-angle scattering datasets simultaneously: on the\n  optimal use of priors and weights: Small-angle X-ray and neutron scattering (SAXS and SANS) are powerful\ntechniques for elucidating the structure of diverse particles and materials.\nThis study address the challenge of effectively combining SAXS and SANS data\nfor accurate structural parameter determination. Surprisingly, our results\ndemonstrate that equally weighting all data points leads to the most accurate\nparameter estimation, even when SAXS data significantly outnumber SANS data. We\ncompared this approach with weighting schemes normalized by the number of\npoints and by the derived information content. Furthermore, we assessed the\nimpact of prior knowledge by incorporating Gaussian priors for model\nparameters. Our findings indicate that Gaussian priors improve the accuracy of\nrefined parameter values compared to uniform priors. When using a minimum and a\nmaximum values for model parameters, which is common practice, uniform priors\nare implicitely applied. Finally, we show that utilizing information content\naids in determining the degrees of freedom, enabling accurate calculation of\nthe goodness of fit. In conclusion, this research provides valuable insights\ninto the optimal combination of SAXS and SANS data, emphasizing the importance\nof weighting schemes and prior knowledge for enhanced accuracy in structural\nparameter determination.",
        "positive": "An artificial dynamic heterogeneity in a glass-former below Tg: We report the first large scale molecular dynamics simulations of the effect\nof the photoisomerization of probe molecules on the dynamics of a glassy\nmolecular material. We show that the photoisomerization of the probe molecules\ninduces the creation of an artificial dynamical heterogeneity inside the\nmatrix. We then study the modification of the dynamics and find, in agreement\nwith recent experiments, an important increase of the diffusion leading to\nliquid like diffusion below the glass transition temperature. We find that the\nphotoisomerization process controls the heterogeneity and the non-Gaussian\nparameter of the material, leading to extremely rapid variations of these\nquantities."
    },
    {
        "anchor": "Spreading law of non-Newtonian power-law liquids on a spherical\n  substrate by energy balance approach: The spreading of a cap-shaped spherical droplet of non-Newtonian power-law\nliquids, both shear-thinning and shear-thinning liquids, that completely wet a\nspherical substrate is theoretically investigated in the capillary-controlled\nspreading regime. The crater-shaped droplet model with the wedge-shaped\nmeniscus near the three-phase contact line is used to calculate the viscous\ndissipation near the contact line. Then the energy balance approach is adopted\nto derive the equation which governs the evolution of the contact line. The\ntime evolution of the dynamic contact angle $\\theta$ of a droplet obeys a power\nlaw $\\theta \\sim t^{-\\alpha}$ with the spreading exponent $\\alpha$, which is\ndifferent from Tanner's law for Newtonian liquids and those for non-Newtonian\nliquids on a flat substrate. Furthermore, the line-tension dominated spreading,\nwhich could be realized on a spherical substrate for late-stage of spreading\nwhen the contact angle becomes low and the curvature of the contact line\nbecomes large, is also investigated.",
        "positive": "Equation of State Based Slip Spring Model for Entangled Polymer Dynamics: A mesoscopic, mixed particle- and field-based Brownian dynamics methodology\nfor the simulation of entangled polymer melts has been developed. Polymeric\nbeads consist of several Kuhn segments, and their motion is dictated by the\nHelmholtz energy of the sample, which is a sum of the entropic elasticity of\nchain strands between beads, slip springs, and nonbonded interactions. The\nentanglement effect is introduced by the slip springs, which are springs\nconnecting either nonsuccessive beads on the same chain or beads on different\npolymer chains. The terminal positions of slip springs are altered during the\nsimulation through a kinetic Monte Carlo hopping scheme, with rate-controlled\ncreation/destruction processes for the slip springs at chain ends. The rate\nconstants are consistent with the free energy function employed and satisfy\nmicroscopic reversibility at equilibrium. The free energy of nonbonded\ninteractions is derived from an appropriate equation of state, and it is\ncomputed as a functional of the local density by passing an orthogonal grid\nthrough the simulation box; accounting for it is necessary for reproducing the\ncorrect compressibility of the polymeric material. Parameters invoked by the\nmesoscopic model are derived from experimental volumetric and viscosity data or\nfrom atomistic molecular dynamics simulations, establishing a \"bottom-up\"\npredictive framework for conducting slip spring simulations of polymeric\nsystems of specific chemistry. The mesoscopic simulation methodology is\nimplemented for the case of cis-1,4-polyisoprene, whose structure, dynamics,\nthermodynamics, and linear rheology in the melt state are quantitatively\npredicted and validated without a posteriori fitting the results to\nexperimental measurements."
    },
    {
        "anchor": "Mode-Coupling Theory for Tagged-Particle Motion of Active Brownian\n  Particles: We derive a mode-coupling theory (MCT) to describe the dynamics of tracer\nparticles in dense systems of active Brownian particles (ABPs) in two spatial\ndimensions. The ABP undergo translational and rotational Brownian dynamics, and\nare equipped with a fixed self-propulsion speed along their orientational\nvector that describes their active motility. The resulting equations of motion\nfor the tagged-particle density correlation functions describe the various\ncases of tracer dynamics close to the glass transition: that of a passive\ncolloidal particle in a suspension of ABP, that of a single active particle in\na glass-forming passive host suspensions, and that of active tracers in a bath\nof active particles. Numerical results are presented for these cases assuming\nhard-sphere interactions among the particles. The qualitative and quantitative\naccuracy of the theory is tested against event-driven Brownian dynamics (ED-BD)\nsimulations of active and passive hard disks. Simulation and theory are found\nin quantitative agreement, provided one adjusts the overall density (as known\nfrom the passive description of glassy dynamics), and allows for a rescaling of\nself-propulsion velocities in the active host system. These adjustments account\nfor the fact that ABP-MCT generally overestimates the tendency for kinetic\narrest. We also confirm in the simulations a peculiar feature of the transient\nand stationary dynamical density correlation functions regarding their lack of\nsymmetry under time reversal, demonstrating the non-equilibrium nature of the\nsystem and how it manifests itself in the theory.",
        "positive": "Command of Collective Dynamics by Topological Defects in Spherical\n  Crystals: Directing individual motions of many constituents to coherent dynamical state\nis a fundamental challenge in multiple fields. Here, based on the spherical\ncrystal model, we show that topological defects in particle arrays can be a\ncrucial element in regulating collective dynamics. Specifically, we highlight\nthe defect-driven synchronized breathing modes around disclinations and\ncollective oscillations with strong connection to disruption of crystalline\norder. This work opens the promising possibility of an organizational principle\nbased on topological defects, and may inspire new strategies for harnessing\nintriguing collective dynamics in extensive nonequilibrium systems."
    },
    {
        "anchor": "Unusual transformation of polymer coils in a mixed solvent close to the\n  critical point: We have discovered unusual behavior of polymer coils in a binary solvent\n(nitroethane+isooctane) near the critical temperature of demixing. The\nexceptionally close refractive indices of the solvent components make the\ncritical opalescence relatively weak, thus enabling us to simultaneously\nobserve the Brownian motion of the polymer coils and the diverging correlation\nlength of the critical fluctuations. The polymer coils exhibit a\ncollapse-reswelling-expansion-collapse transition upon approaching the critical\ntemperature. While the first stage (collapse-reswelling) can be explained by\nthe theory of Brochard and de Gennes, the subsequent expansion-collapse\ntransition is a new unexpected phenomenon that has not been observed so far. We\nbelieve that this effect is generic and attribute it to micro-phase separation\nof the solvent inside the polymer coil.",
        "positive": "Structure and Properties of Thermoresponsive Diblock Copolymers Embedded\n  with Metal Oxide Nanoparticles: Nanostructured polymer-metal oxide composites are a current research area of\ngreat importance due to its highlight applications in sensors, optics,\ncatalysts and drug delivery. Particularly the use of thermoresponsive polymers\ngives more flexibilities and possibilities in the design and construction of\npolymer templates. In the present investigation, the structure and magnetic\nproperties of hybrid metal oxide/DBC films composed of two kinds of\npolystyrene-block-poly (N-isopropylacrylamide)(PS-b-PNIPAM) diblock copolymers\n(DBCs) with PS and PNIPAM as the major polymer domains respectively, and iron\noxide were investigated. The thermoresponsive PNIPAM has a lower critical\nsolution temperature (LCST) in aqueous solution at 32{\\deg}C, which enables the\ncontrollable volume ratio of PS and PNIPAM in the structure of PS-b-PNIPAM\ndiblock copolymers (DBCs). Thus, a temperature and humidity controlling cell\nwas designed and built for precisely tuning the block structure of PS-b-PNIPAM\nDBCs, which was investigated by in-situ small-angle X-ray scattering (SAXS) and\ngrazing-incidence small-angle X-ray scattering (GISAXS) measurements. The\nsuperparamagnetic behavior of the heat-treated hybrid iron oxide/PS-b-PNIPAM\nDBC films was investigated using a superconducting quantum interference device\n(SQUID) magnetometer."
    },
    {
        "anchor": "Effect of the Nature of the Solid Substrate on Spatially Heterogeneous\n  Activated Dynamics in Glass Forming Supported Films: We extend the force-level ECNLE theory to treat the spatial gradients of the\nalpha relaxation time and glass transition temperature, and the corresponding\nfilm-averaged quantities, to the geometrically asymmetric case of finite\nthickness supported films with variable fluid - substrate coupling. The latter\ntypically nonuniversally slows down motion near the solid-liquid interface as\nmodeled via modification of the surface dynamic free energy caging constraints\nwhich are spatially transferred into the film, and which compete with the\naccelerated relaxation gradient induced by the vapor interface. Quantitative\napplications to the foundational hard sphere fluid and a polymer melt are\npresented. The strength of the effective fluid-substrate coupling has very\nlarge consequences on the dynamical gradients and film-averaged quantities in a\nfilm thickness and thermodynamic state dependent manner. The interference of\nthe dynamical gradients of opposite nature emanating from the vapor and solid\ninterfaces is determined, including the conditions for the disappearance of a\nbulk-like region in the film center. The relative importance of surface-induced\nmodification of local caging versus the generic truncation of the long range\ncollective elastic component of the activation barrier is studied. The\nconditions for the accuracy and failure of a simple superposition approximation\nfor dynamical gradients in thin films is also determined. The emergence of near\nsubstrate dead layers, large gradient effects on film-averaged response\nfunctions, and a weak non-monotonic evolution of dynamic gradients in thick and\ncold films, are briefly discussed. The connection of our theoretical results to\nsimulations and experiments is briefly discussed, as is extension to treat more\ncomplex glass-forming systems under nanoconfinement.",
        "positive": "Wrinkling of microcapsules in shear flow: Elastic capsules can exhibit short wavelength wrinkling in external shear\nflow. We analyse this instability of the capsule shape and use the length scale\nseparation between the capsule radius and the wrinkling wavelength to derive\nanalytical results both for the threshold value of the shear rate and for the\ncritical wave-length of the wrinkling. These results can be used to deduce\nelastic parameters from experiments."
    },
    {
        "anchor": "Ergodicity breaking transition in a glassy soft sphere system at small\n  but non-zero temperatures: While the glass transition at non-zero temperature seems to be hard to access\nfor experimental, theoretical, or simulation studies, jamming at zero\ntemperature has been explored in great detail. It is a widely discussed\nquestion whether this athermal jamming transition is related to the glass\ntransition. Motivated by the exploration of the energy landscape that has been\nsuccessfully used to describe athermal jamming, we introduce a new method to\ndetermine whether the configuration space of a soft sphere system can be\nexplored within a reasonable timescale or not, i.e., whether the system is\nergodic or effectively non-ergodic. While in case of athermal jamming for a\ngiven random starting configuration only the local energy minimum is\ndetermined, we allow the thermally excited crossing of energy barriers.\nInterestingly, we observe that a transition exists where the system becomes\neffectively non-ergodic if the density is increased. In the limit of small but\nnon-zero temperatures the density where the ergodicity breaking transition\noccurs approaches a value that is independent of temperature and below the\ntransition density of athermal jamming. This confirms recent computer\nsimulation studies where athermal jamming occurs deep inside the glass phase.\nIn addition, with our method we determined the critical behavior of the\nergodicity breaking transition and show that it is in the universality class of\ndirected percolation. Therefore, our approach not only makes the transition\nfrom an ergodic to an effectively non-ergodic systems easily accessible and\nhelps to reveal its universality class but also shows that it is fundamentally\ndifferent from athermal jamming.",
        "positive": "Hexatic phase and cluster crystals of two-dimensional GEM4 spheres: Two-dimensional crystals of classical particles are very peculiar in that\nmelting may occur in two steps, in a continuous fashion, via an intermediate\nhexatic fluid phase exhibiting quasi-long-range orientational order. On the\nother hand, three-dimensional spheres repelling each other through a\nfast-decaying bounded potential of generalized-exponential shape (GEM4\npotential) can undergo freezing into cluster crystals, allowing for more that\none particle per lattice site. We hereby study the combined effect of low\nspatial dimensionality and extreme potential softness, by investigating the\nphase behavior of the two-dimensional (2D) GEM4 system. Using a combination of\ndensity-functional theory and numerical free-energy calculations, we show that\nthe 2D GEM4 system displays one ordinary and several cluster triangular-crystal\nphases, and that only the ordinary crystal first melts into a hexatic phase.\nUpon heating, the difference between the various cluster crystals fades away,\neventually leaving a single undifferentiated cluster phase with a\npressure-modulated site occupancy."
    },
    {
        "anchor": "Driving forces on dislocations due to strain gradients and higher order\n  gradients: Dislocations are topological defects known to be crucial in the onset of\nplasticity and in many properties of crystals. Classical Elasticity still fails\nto fully explain their dynamics under extreme conditions of high strain\ngradients and small scales, which can nowadays be scrutinized. In such\nconditions, corrections to the Volterra dislocation fields and to the\nPeach-Koehler force, for example, become relevant. One way to go beyond the\nVolterra solution is to consider other terms in the total Laurent series\nsolution. This is the so called core field. One of its consequences is to\npredict a driving force on the dislocation due to background strain/stress\ngradients, which has also been suggested by other core energy calculations.\nHere we confirm its existence by presenting a direct observation of strain\ngradients driving edge dislocations in 2D atomistic simulations. We show that,\nin systems with scale invariance, the results for such core force can be used\nto obtain the total core energy, allowing a standard value for this energy to\nbe compared with other classical methods of obtaining it. The force measured in\nour system differs from the prediction obtained by a direct core field\nanalysis. Moreover, we found that higher order gradients of strains can also\nact as relevant forces.",
        "positive": "Bond disorder, frustration and polymorphism in the spontaneous\n  crystallization of a polymer melt: The isothermal, isobaric spontaneous crystallization of a supercooled polymer\nmelt is investigated by MD simulation of an ensemble of fully-flexible linear\nchains. Frustration is introduced via two incommensurate length scales set by\nthe bond length and the position of the minimum of the non-bonding potential.\nMarked polymorphism with considerable bond disorder, distortions of both the\nlocal packing and the global monomer arrangements is observed. The analyses in\nterms of: i) orientational order parameters characterizing the global and the\nlocal order and ii) the angular distribution of the next-nearest neighbors of a\nmonomer reach the conclusion that the polymorphs are arranged in distorted\nBcc-like lattices."
    },
    {
        "anchor": "Spool-nematic ordering of dsDNA and dsRNA under confinement: The ability of double-stranded DNA or RNA to locally melt and form kinks\nleads to strong non-linear elasticity effects that qualitatively affect their\npacking in confined spaces. Using analytical theory and numerical simulation we\nshow that kink formation entails a mixed spool-nematic ordering of\ndouble-stranded DNA or RNA in spherical capsids, consisting of an outer spool\ndomain and an inner, twisted nematic domain. These findings explain the\nexperimentally observed nematic domains in viral capsids and imply that\nnon-linear elasticity must be considered to predict the configurations and\ndynamics of double-stranded genomes in viruses, bacterial nucleoids or\ngene-delivery vehicles.",
        "positive": "Colorimetric path tagging of filaments using DNA-based metafluorophores: The idea is a nanoscale extension of a sporting event called a `color run'.\nThe filament is wrapped with a DNA origami `barrel', which acts as the\nnanoscale equivalent of a white t-shirt. The DNA t-shirt has dangling ss-DNA\n`handles' that bind `tags' consisting of an `anti-handle' oligo bound to a\nfluorophore. The tagging methodology exploits the recent development of\nDNA-based `metafluorophores' with digitally tunable optical properties based on\na collection of fluorophores bound to a single DNA origami structure. In this\nidea, the filament collects different color tags at `color-stations' as it\ntravels through the network. These contribute to a final DNA t-shirt color that\nrepresents of the path taken. Readout is implemented through lenseless on-chip\nimaging via pixels in a CMOS backplane located at read-out points in the\nnetwork. Color-stations are implemented via microfluidic channels on a dialysis\nmembrane, which feed tags into the network in localised areas. A chemical\ncountermeasure to prevent false tagging by stray tags that have drifted in from\nother stations by exploiting strand-displacement technique is also proposed."
    },
    {
        "anchor": "Topological states in chiral active matter: dynamic blue phases and\n  active half-skyrmions: We numerically study the dynamics of two-dimensional blue phases in active\nchiral liquid crystals. We show that introducing contractile activity results\nin stabilised blue phases, while small extensile activity generates ordered but\ndynamic blue phases characterised by coherently moving half-skyrmions and\ndisclinations. Increasing extensile activity above a threshold leads to the\ndissociation of the half-skyrmions and active turbulence. We further analyse\nisolated active half-skyrmions in an isotropic background and compare the\nactivity-induced velocity fields in simulations to an analytical prediction of\nthe flow. Finally, we show that confining an active blue phase can give rise to\na system-wide circulation, in which half-skyrmions and disclinations rotate\ntogether.",
        "positive": "Hydrogen-bond relaxation dynamics: Resolving mysteries of water ice: We examined O:H-O bond relaxation under compression,heating,molecular\nundercoordination and claimed a universal resolution to the best-known\nmysteries of water ice such as ice foating, ice slipperiness, relegation and\nwarm water cools faster. progress shows that O:H-O bond segmental disparity and\nO-O repulsivity form the soul dictating the extraordinary adaptivity,\ncooperativity, recoverability, and sensitivity of water and ice."
    },
    {
        "anchor": "Conformations of dendrimers in dilute solution: Conformations of isolated homo- dendrimers of G=1-7 generations with D=1-6\nspacers have been studied in the good and poor solvents, as well as across the\ncoil-to-globule transition, by means of a version of the Gaussian\nself-consistent (GSC) method and Monte Carlo (MC) simulation in continuous\nspace based on the same coarse-grained model. The latter includes harmonic\nsprings between connected monomers and the pair-wise Lennard-Jones potential\nwith a hard core repulsion. The scaling law for the dendrimer size, the degrees\nof bond stretching and steric congestion, as well as the radial density, static\nstructure factor, and asphericity have been analysed. It is also confirmed that\nwhile smaller dendrimers have a dense core, larger ones develop a hollow domain\nat some separation from the centre.",
        "positive": "Chemical Reactions regulated by Phase-Separated Condensates: Phase-separated liquid condensates can spatially organize and thereby\nregulate chemical processes. However, the physicochemical mechanisms underlying\nsuch regulation remain elusive as the intramolecular interactions responsible\nfor phase separation give rise to a coupling between diffusion and chemical\nreactions at non-dilute conditions. Here, we derive a theoretical framework\nthat decouples the phase separation of scaffold molecules from the reaction\nkinetics of diluted clients. As a result, phase volume and client partitioning\ncoefficients become control parameters, which enables us to dissect the impact\nof phase-separated condensates on chemical reactions. We apply this framework\nto two chemical processes and show how condensates affect the yield of\nreversible chemical reactions and the initial rate of a simple assembly\nprocess. In both cases, we find an optimal condensate volume at which the\nrespective chemical reaction property is maximal. Our work can be applied to\nexperimentally quantify how condensed phases alter chemical processes in\nsystems biology and unravel the mechanisms of how biomolecular condensates\nregulate biochemistry in living cells."
    },
    {
        "anchor": "Shearing active gels close to the isotropic-nematic transition: We study numerically the rheological properties of a slab of active gel close\no the isotropic-nematic transition. The flow behavior shows strong dependence\non sample size, boundary conditions, and on the bulk constitutive curve, which,\non entering the nematic phase, acquires an activity-induced discontinuity at\nthe origin. The precursor of this within the metastable isotropic phase for\ncontractile systems ({\\em e.g.,} actomyosin gels) gives a viscosity divergence;\nits counterpart for extensile ({\\em e.g.,} {\\em B. subtilis}) suspensions\nadmits instead a shear-banded flow with zero apparent viscosity.",
        "positive": "Properties of aqueous electrolyte solutions at carbon electrodes:\n  effects of concentration and surface charge on solution structure, ion\n  clustering and thermodynamics in the electric double layer: Surfaces are able to control physical-chemical processes in multi-component\nsolution systems and, as such, find application in a wide range of\ntechnological devices. Understanding the structure, dynamics and thermodynamics\nof non-ideal solutions at surfaces, however, is particularly challenging. Here,\nwe use Constant Chemical Potential Molecular Dynamics simulations to gain\ninsight into aqueous NaCl solutions in contact with graphite surfaces at high\nconcentrations and under the effect of applied surface charges: conditions\nwhere mean-field theories describing interfaces cannot (typically) be reliably\napplied. We discover an asymmetric effect of surface charge on the electric\ndouble layer structure and resulting thermodynamic properties, which can be\nexplained by considering the affinity of the surface for cations and anions and\nthe cooperative adsorption of ions that occurs at higher concentrations. We\ncharacterise how the sign of the surface charge affects ion densities and water\nstructure in the double layer and how the capacitance of the interface - a\nfunction of the electric potential drop across the double layer - is largely\ninsensitive to the bulk solution concentration. Notably, we find that\nnegatively charged graphite surfaces induce an increase in the size and\nconcentration of extended liquid-like ion clusters confined to the double\nlayer. Finally, we discuss how concentration and surface charge affect the\nactivity coefficients of ions and water at the interface, demonstrating how\nelectric fields in this region should be explicitly considered when\ncharacterising the thermodynamics of both solute and solvent at the\nsolid/liquid interface."
    },
    {
        "anchor": "Electric field based Poisson-Boltzmann: Treating mobile charge as\n  polarization: Mobile charge in an electrolytic solution can in principle be represented as\nthe divergence of ionic polarization. After adding explicit solvent\npolarization a finite volume of electrolyte can then be treated as a composite\nnon-uniform dielectric body. Writing the electrostatic interactions as an\nintegral over electric field energy density we show that the Poisson-Boltzmann\nfunctional in this formulation is convex and can be used to derive the\nequilibrium equations for electric potential and ion concentration by a\nvariational procedure developed by Ericksen for dielectric continua (Arch.\nRational Mech. Anal. 2007, 183, 299-313). The Maxwell field equations are\nenforced by extending the set of variational parameters by a vector potential\nrepresenting the dielectric displacement which is fully transverse in a\ndielectric system without embedded external charge. The electric field energy\ndensity in this representation is a function of the vector potential and the\nsum of ionic and solvent polarization making the mutual screening explicit.",
        "positive": "Membrane fouling: microscopic insights into the effects of surface\n  chemistry and roughness: Fouling is a major obstacle and challenge in membrane-based separation\nprocesses. Caused by the sophisticated interactions between foulant and\nmembrane surface, fouling strongly depends on membrane surface chemistry and\nmorphology. Current studies in the field have been largely focused on polymer\nmembranes. Herein, we report a molecular simulation study for fouling on\nalumina and graphene membrane surfaces during water treatment. For two foulants\n(sucralose and bisphenol A), the fouling on alumina surfaces is reduced with\nincreasing surface roughness; however, the fouling on graphene surfaces is\nenhanced by roughness. It is unravelled that the foulant-surface interaction\nbecomes weaker in the ridge region of a rough alumina surface, thus allowing\nfoulant to leave the surface and reducing fouling. Such behavior is not\nobserved on a rough graphene surface because of the strong foulant-graphene\ninteraction. Moreover, with increasing roughness, the hydrogen bonds formed\nbetween water and alumina surfaces are found to increase in number as well as\nstability. By scaling the atomic charges of alumina, fouling behavior on\nalumina surfaces is shifted to the one on graphene surfaces. This simulation\nstudy reveals that surface chemistry and roughness play a crucial role in\nmembrane fouling, and the microscopic insights are useful for the design of new\nmembranes towards high-performance water treatment."
    },
    {
        "anchor": "Evolution of liquid crystal microstructure during shape memory sequence\n  in two main-chain polydomain smectic-C elastomers: Structural studies by synchrotron x-ray diffraction on two main-chain\nsmectic-C elastomers reveal the presence of two different relaxation mechanisms\nin these systems at low and high strains. At low strains, the smectic layers\nare reoriented with layer-normals distributed in a plane perpendicular to the\nstretch direction. The system relaxes relatively slowly (time-constant ~ 45\nminutes) which is attributed to the flow properties of the LC layers embedded\nin the elastomer network. At high strains, the equilibration time (~ 4 - 8\nminutes) conforms to a faster relaxation and appears to have its origin in the\npolymer components of the system. Due to misaligned microdomains at small\nstrains, the value of global orientational order parameter S for the mesogenic\nparts is initially small (~ 0.15). With increasing strain, the local\ndomain-directors, the mesogens, and the polymer chains, all tend to align\nparallel to the stretch direction giving rise to a higher measured value of S ~\n0.83 at a strain of 4.0. The siloxane segments remain less ordered, attaining a\nvalue of S ~ 0.4 for a strain of 4.0. The layers gradually become oblique to\nthe stretch direction conforming to the structural property of the smectic-C\nphase. The system finally assumes a chevron-like optically monodomain\nstructure. Both elastomers are locked-in this state even after removal of the\nexternal stress giving rise to strain retention and the shape memory effect.\nThe presence of a transverse component in the main-chain leads to higher strain\nretention in the second elastomer. A preference for the orientation of the\nsmectic layer-normals toward the stretch direction persists after removal of\nexternal stress. Upon thermal annealing, the chevron-like microstructure\ngradually melts via a different path to the initial polydomain structure.",
        "positive": "Charge inversion at minute electrolyte concentrations: Anionic DMPA monolayers spread on LaCl$_3$ solutions reveal strong cation\nadsorption and a sharp transition to surface overcharging at unexpectedly low\nbulk salt concentrations. We determine the surface accumulation of La$^{3+}$\nwith anomalous x-ray reflectivity and find that La$^{3+}$ compensates the lipid\nsurface charge by forming a Stern layer with $\\approx 1$ La$^{3+}$ ion per 3\nlipids below a critical bulk concentration, $c_t \\approx 500 \\mathrm{nM}$.\nAbove $c_t$, the surface concentration of La$^{3+}$ increases to a saturation\nlevel with $\\approx 1$ La$^{3+}$ per lipid, thus implying that the total\nelectric charge of the La$^{3+}$ exceeds the surface charge. This overcharge is\nobserved at $\\approx$ 4 orders of magnitude lower concentration than predicted\nin ion-ion correlation theories. We suggest that transverse electrostatic\ncorrelations between mobile ions and surface charges (interfacial Bjerrum\npairing) may account for the charge inversion observed in this dilute regime."
    },
    {
        "anchor": "Coarse-Grained Model for Phospholipid/Cholesterol Bilayer: We construct a coarse-grained (CG) model for dipalmitoylphosphatidylcholine\n(DPPC)/cholesterol bilayers and apply it to large-scale simulation studies of\nlipid membranes. Our CG model is a two-dimensional representation of the\nmembrane, where the individual lipid and sterol molecules are described by\npoint-like particles. The effective intermolecular interactions used in the\nmodel are systematically derived from detailed atomic-scale molecular dynamics\nsimulations using the Inverse Monte Carlo technique, which guarantees that the\nradial distribution properties of the CG model are consistent with those given\nby the corresponding atomistic system. We find that the coarse-grained model\nfor the DPPC/cholesterol bilayer is substantially more efficient than atomistic\nmodels, providing a speed-up of approximately eight orders of magnitude. The\nresults are in favor of formation of cholesterol-rich and cholesterol-poor\ndomains at intermediate cholesterol concentrations, in agreement with the\nexperimental phase diagram of the system. We also explore the limits of the\nnovel coarse-grained model, and discuss the general validity and applicability\nof the present approach.",
        "positive": "Connecting Structural Relaxation with the Low Frequency Modes in a\n  Hard-Sphere Colloidal Glass: Structural relaxation in hard-sphere colloidal glasses has been studied using\nconfocal microscopy. The motion of individual particles is followed over long\ntime scales to detect the rearranging regions in the system. We have used\nnormal mode analysis to understand the origin of the rearranging regions. The\nlow frequency modes, obtained over short time scales, show strong spatial\ncorrelation with the rearrangements that happen on long time scales."
    },
    {
        "anchor": "Effects of particle roughness on the rheology and structure of capillary\n  suspensions: We show that particle roughness leads to changes in the number, shape and\nresulting capillary force of liquid bridges in capillary suspensions. We\ncreated fluorescently labeled, raspberry-like particles with varying roughness\nby electrostatically adsorbing silica nanoparticles with sizes between 40 nm\nand 250 nm on silica microparticles. Rougher particles require more liquid to\nfill the surface asperities before they form pendular bridges, resulting in\nsmaller and weaker bridges. In a system where the effective bridge volume is\nadjusted, higher particle roughness leads to less clustered networks, which\nshow a higher yield strain for a matching storage modulus compared to the\nsmooth particle networks. This finding suggests that the particle-particle\nfrictional contacts also affects the strength of capillary suspensions. Using\nasymptotically nonlinear oscillatory rheology, we corroborate the non-cubical\npower law scaling of the third harmonic in the shear stress response that\nresults from both Hertzian contacts and friction between particles connected by\ncapillary bridges. We demonstrate that the repulsive Hertzian contact parameter\n$A$ is sensitive to the liquid bridge strength and that roughness appears to\nshift the relative scaling of the power law exponents from adhesive-controlled\nfriction to load-controlled friction.",
        "positive": "Modulation of ionic conduction using polarizable surfaces: Hybrid ionic-electronic conductors have the potential to generate memory\neffects and neuronal behavior. The functionality of these mixed materials\ndepends on ion motion through thin polarizable channels. Here, we explore\ndifferent polarization models to show that the current and conductivity of\nelectrolytes is higher when confined by conductors than by dielectrics. We find\nnon-linear currents in both dielectrics and conductors, and we recover the\nknown linear (Ohmic) result only in the two-dimensional limit between\nconductors. We show that the polarization charge location impacts electrolyte\nstructure and transport properties. This work suggests a mechanism to induce\nmemristor hysteresis loops using conductor-dielectric switchable materials."
    },
    {
        "anchor": "Jamming as a Multicritical Point: The discontinuous jump in the bulk modulus $B$ at the jamming transition is a\nconsequence of the formation of a critical contact network of spheres that\nresists compression. We introduce lattice models with underlying\nunder-coordinated compression resistant spring lattices to which\nnext-nearest-neighbor springs can be added. In these models, the jamming\ntransition emerges as a kind of multicritical point terminating a line of\nrigidity-percolation transitions. Replacing the under-coordinated lattices with\nthe critical network at jamming yields a faithful description of jamming and\nits relation to rigidity percolation.",
        "positive": "Non-Fickian macroscopic model of axial diffusion of granular materials\n  in a long cylindrical tumbler: We provide new concepts for understanding transport phenomena in flows of\ngranular materials by using a non-Fickian macroscopic model of axial diffusion\nof a granular material in a finite cylindrical tumbler. The model accounts for\ndiffusion induced by particle collisions only in a thin surface flowing layer\ndue to localization of shear within the cross-section of the drum. All model\nparameters are related to measurable quantities in a granular flow. It is shown\nthat the proposed model is a member of the general class of linear constitutive\nrelations with memory. An exact solution for the spreading of a finite-width\npulse initial condition under the proposed non-Fickian model is derived and\ncompared to the solution of a Fickian model (i.e., the ``classical'' diffusion\nequation)."
    },
    {
        "anchor": "Electrostatic interactions in critical solvents: The subtle interplay between critical phenomena and electrostatics is\ninvestigated by considering the effective force acting on two parallel walls\nconfining a near-critical binary liquid mixture with added salt. The\nion-solvent coupling can turn a non-critical repulsive electrostatic force into\nan attractive one upon approaching the critical point. However, the effective\nforce is eventually dominated by the critical Casimir effect, the universal\nproperties of which are not altered by the presence of salt. This observation\nallows a consistent interpretation of recent experimental data.",
        "positive": "Steady base states for non-Newtonian granular hydrodynamics: We study in this work steady laminar flows in a low density granular gas\nmodelled as a system of identical smooth hard spheres that collide\ninelastically. The system is excited by shear and temperature sources at the\nboundaries, which consist of two infinite parallel walls. Thus, the geometry of\nthe system is the same that yields the planar Fourier and Couette flows in\nstandard gases. We show that it is possible to describe the steady granular\nflows in this system, even at large inelasticities, by means of a\n(non-Newtonian) hydrodynamic approach. All five types of Couette-Fourier\ngranular flows are systematically described, identifying the different types of\nhydrodynamic profiles. Excellent agreement is found between our classification\nof flows and simulation results. Also, we obtain the corresponding non-linear\ntransport coefficients by following three independent and complementary\nmethods: (1) an analytical solution obtained from Grad's 13-moment method\napplied to the inelastic Boltzmann equation, (2) a numerical solution of the\ninelastic Boltzmann equation obtained by means of the direct simulation Monte\nCarlo method and (3) event-driven molecular dynamics simulations. We find that,\nwhile Grad's theory does not describe quantitatively well all transport\ncoefficients, the three procedures yield the same general classification of\nplanar Couette-Fourier flows for the granular gas"
    },
    {
        "anchor": "Kinetic Friction by a Small Number of Intervening Inelastic Particles\n  between Rough Surfaces: We investigate a mechanism of the appearance of kinetic friction in granular\nmaterials. We consider a small number of intervening inelastic particles\nbetween two rough surfaces as one of the simplest dynamical models to study\ngranular friction. The resistance force applied to the upper surface is\nnumerically calculated. We find that the resistance force F(t) is scaled as\nF'(vt) for a small pulling velocity v. The time average F_0=<F(t)> in the limit\nv->0 is not zero owing to the mutual collisions between the intervening\nparticles. The nonzero F_0 implies the appearance of kinetic friction in this\nsimple dynamical system.",
        "positive": "The existence of a bending rigidity for a hard sphere liquid near a\n  curved hard wall: Helfrich or Hadwiger?: In the context of Rosenfeld's Fundamental Measure Theory, we show that the\nbending rigidity is not equal to zero for a hard-sphere fluid in contact with a\ncurved hard wall. The implication is that the Hadwiger Theorem does not hold in\nthis case and the surface free energy is given by the Helfrich expansion\ninstead. The value obtained for the bending rigidity is (1) an order of\nmagnitude smaller than the bending constant associated with Gaussian curvature,\n(2) changes sign as a function of the fluid volume fraction, (3) is independent\nof the choice for the location of the hard wall."
    },
    {
        "anchor": "A lattice Boltzmann model for self-diffusiophoretic particles near and\n  at liquid-liquid interfaces: We introduce a novel mesoscopic computational model based on a\nmultiphase-multicomponent lattice Boltzmann method for the simulation of\nself-phoretic particles in the presence of liquid-liquid interfaces. Our model\nfeatures fully resolved solvent hydrodynamics and, thanks to its versatility,\nit can handle important aspects of the multiphysics of the problem, including\nparticle wettability and differential solubility of the product in the two\nliquid phases. The method is extensively validated in simple numerical\nexperiments, whose outcome is theoretically predictable, and then applied to\nthe study of the behaviour of active particles next to and trapped at\ninterfaces. We show that their motion can be variously steered by tuning\nrelevant control parameters, such as the phoretic mobilities, the contact angle\nand the product solubility.",
        "positive": "Lorentz Reciprocal Theorem in Fluids with Odd Viscosity: The Lorentz reciprocal theorem -- that is used to study various transport\nphenomena in hydrodynamics -- is violated in chiral active fluids that feature\nodd viscosity with broken time-reversal and parity symmetries. Here we show\nthat the theorem can be generalized to fluids with odd viscosity by choosing an\nauxiliary problem with the opposite sign of the odd viscosity. We demonstrate\nthe application of the theorem to two categories of microswimmers. Swimmers\nwith prescribed surface velocity are not affected by odd viscosity, while those\nwith prescribed active forces are. In particular, a torque-dipole can lead to\ndirected motion."
    },
    {
        "anchor": "An energy landscape model for glass forming liquids in three dimensions: We present a three-dimensional lattice-gas model with trivial thermodynamics,\nbut nontrivial dynamics. The model is characterized by each particle having its\nown random energy landscape. The equilibrium dynamics of the model were\ninvestigated by continuous time Monte Carlo simulations at two different\ndensities at several temperatures. At high densities and low temperatures the\nmodel captures the important characteristics of viscous liquid dynamics. We\nthus observe non-exponential relaxation in the self part of the density\nauto-correlation function, and fragility plots of the self-diffusion constant\nand relaxation times show non-Arrhenius behavior.",
        "positive": "Susceptibility of Orientationally-Ordered Active Matter to Chirality\n  Disorder: We investigate the susceptibility of long-range ordered phases of\ntwo-dimensional dry aligning active matter to population disorder, taken in the\nform of a distribution of intrinsic individual chiralities. Using a combination\nof particle-level models and hydrodynamic theories derived from them, we show\nthat while in finite systems all ordered phases resist a finite amount of such\nchirality disorder, the homogeneous ones (polar flocks and active nematics) are\nunstable to any amount of disorder in the infinite-size limit. On the other\nhand, we find that the inhomogeneous solutions of the coexistence phase (bands)\nmay resist a finite amount of chirality disorder even asymptotically."
    },
    {
        "anchor": "The EXP pair-potential system. II. Fluid phase isomorphs: This paper continues the investigation of the exponentially repulsive EXP\npair-potential system of Paper I with a focus on isomorphs in the\nlow-temperature gas and liquid phases. As expected from the EXP system's strong\nvirial potential-energy correlations, the system's reduced-unit structure and\ndynamics are isomorph invariant to a good approximation. Three methods for\ngenerating isomorphs are compared: the small-step method that is exact in the\nlimit of small density changes and two versions of the direct-isomorph-check\nmethod that allows for much larger density changes. Results from approximate\nmethods are compared to those of the small-step method for each of three\nisomorphs generated by 230 one percent density increases, covering in all one\ndecade of density variation. Both approximate methods work well.",
        "positive": "Tumbling motion of a single chain in shear flow: a crossover from\n  Brownian to non-Brownian behavior: We present numerical results for the dynamics of a single chain in steady\nshear flow. The chain is represented by a bead-spring model, and the smoothed\nprofile method is used to accurately account for the effects of thermal\nfluctuations and hydrodynamic interactions acting on beads due to host fluids.\nIt is observed that the chain undergoes tumbling motions and that its\ndimensionless frequency F depends only on the Peclet number Pe with a power\nlaw. The exponent of Pe clearly changes from 2/3 to 1 around the critical\nPeclet number, indicating that the crossover reflects the competition of\nthermal fluctuation and shear flow. The presented numerical results agree well\nwith our theoretical analysis based on Jeffery's work."
    },
    {
        "anchor": "Structural transitions and arrest of domain growth in sheared binary\n  immiscible fluids and microemulsions: We investigate spinodal decomposition and structuring effects in binary\nimmiscible and ternary amphiphilic fluid mixtures under shear by means of three\ndimensional lattice Boltzmann simulations. We show that the growth of\nindividual fluid domains can be arrested by adding surfactant to the system,\nthus forming a bicontinous microemulsion. We demonstrate that the maximum\ndomain size and the time of arrest depend linearly on the concentration of\namphiphile molecules. In addition, we find that for a well defined threshold\nvalue of amphiphile concentration, the maximum domain size and time of complete\narrest do not change. For systems under constant and oscillatory shear we\nanalyze domain growth rates in directions parallel and perpendicular to the\napplied shear. We find a structural transition from a sponge to a lamellar\nphase by applying a constant shear and the occurrence of tubular structures\nunder oscillatory shear. The size of the resulting lamellae and tubes depends\nstrongly on the amphiphile concentration, shear rate and shear frequency.",
        "positive": "Influence of network topology on the swelling of polyelectrolyte\n  nanogels: It is well-known that the swelling behavior of ionic nanogels depends on\ntheir cross-link density, however it is unclear how different topologies should\naffect the response of the polyelectrolyte network. Here we perform Monte Carlo\nsimulations to obtain the equilibrium properties of ionic nanogels as a\nfunction of salt concentration $C_s$ and the fraction $f$ of ionizable groups\nin a polyelectrolyte network formed by cross-links of functionality $z$. Our\nresults indicate that the network with cross-links of low connectivity result\nin nanogel particles with higher swelling ratios. We also confirm a de-swelling\neffect of salt on nanogel particles."
    },
    {
        "anchor": "Flow equations for dense granular fluids: New insight from a\n  first-principles derivation: We present a first-principles theory for plug-free dense granular flow. This\nis done by coarse-graining directly the microscopic dynamics and deriving an\nexplicit relation between the macroscopic stress and strain rate tensors. The\nnewly derived relation not only differs significantly from that of the existing\nempirical models for such flows but it also provides a novel understanding of\nthe effect of rigid-like rotational regions in the flow.",
        "positive": "Topological transformations of a nematic drop: Morphogenesis of living systems involves topological shape transformations\nwhich are highly unusual in the inanimate world. Here we demonstrate that a\ndroplet of a nematic liquid crystal changes its equilibrium shape from a\nsimply-connected tactoid, which is topologically equivalent to a sphere, to a\ntorus, which is not simply-connected. The topological shape transformation is\ncaused by the interplay of nematic elastic constants, which facilitates splay\nand bend of molecular orientations in tactoids but hinders splay in the\ntoroids. The elastic anisotropy mechanism might be helpful in understanding\ntopology transformations in morphogenesis and paves the way to control and\ntransform shapes of droplets of liquid crystals and related soft materials."
    },
    {
        "anchor": "A closer physico-chemical look to the Layer-by-Layer electrostatic\n  self-assembly of polyelectrolyte multilayers: The fabrication of polyelectrolyte multilayer films (PEMs) using the\nLayer-by-Layer (LbL) method is one of the most versatile approaches for\nmanufacturing functional surfaces. This is the result of the possibility to\ncontrol the assembly process of the LbL films almost at will, by changing the\nnature of the assembled materials (building blocks), the assembly conditions\n(pH, ionic strength, temperature, etc.) or even by changing some other\noperational parameters which may impact in the structure and physico-chemical\nproperties of the obtained multi-layered films. Therefore, the understanding of\nthe impact of the above mentioned parameters on the assembly process of LbL\nmaterials plays a critical role in the potential use of the LbL method for the\nfabrication of new functional materials with technological interest. This\nreview tries to provide a broad physico-chemical perspective to the study of\nthe fabrication process of PEMs by the LbL method, which allows one to take\nadvantage of the many possibilities offered for this approach on the\nfabrication of new functional nanomaterials.",
        "positive": "Multi-Scale Theory of Elasticity for Geomaterials: The modern theory of elasticity and the first law of thermodynamics are\ncornerstones of engineering science that share the concept of reversibility.\nEngineering researchers have known for four decades that the modern theory\nviolates the first law of thermodynamics when applied to the more commonly\naccepted empirical models of geomaterial stiffness. This paper develops a\ncross-scale theory of elasticity that is compatible with the empirical models\nand the first law of thermodynamics. This theory includes a material sample's\ntotal-volume to solid-volume ratio as an independent internal variable,\ndistinguishes deformation into uniform and contraction-swelling components,\nintroduces a uniformity surface that partitions stress space into contraction\nand swelling sub-domains, couples the macroscopic properties to the volume\nratio and extrapolates the accepted empirical models to states that include\nshear stress. This paper broadens the scope of the theory of elasticity to\ninclude soft condensed matter."
    },
    {
        "anchor": "Comment on \"Long-range electrostatic interactions between like-charged\n  colloids: Steric and confinement effects\": In a recent study [Phys. Rev. E 60, 6530 (1999)], Trizac and Raimbault showed\nthat the effective pair interaction between like charged colloids immersed in a\ncylindrically confined electrolyte remains repulsive even when the size of the\nmicro-ions or the finite longitudinal extension of the confining cylinder are\ntaken into account. Contrary to their claim, we argue that the case of finite\nlongitudinal confinement doesn't always generate repulsive interactions and to\nillustrate this point we also provide a simple example.",
        "positive": "Mediating gel formation from structurally controlled poly(electrolytes)\n  through multiple \"head-to-body\" electrostatic interactions: Tuning the chain-end functionality of a short-chain cationic homopolymer,\nowing to the nature of the initiator used in the ATRP polymerisation step, can\nbe used to mediate the formation of a gel of this poly(electrolyte) in water.\nWhile a neutral end group gives a solution of low viscosity, a highly\nhomogeneous gel is obtained with a phosphonate anionic moiety, as characterized\nby rheometry and diffusion NMR. This novel type of supramolecular control over\npoly(electrolytic) gel formation could find potential use in a variety of\napplications in the field of electroactive materials."
    },
    {
        "anchor": "Confinement-induced self-organization in growing bacterial colonies: We investigate the emergence of global alignment in colonies of dividing\nrod-shaped cells under confinement. Using molecular dynamics simulations and\ncontinuous modeling, we demonstrate that geometrical anisotropies in the\nconfining environment give rise to imbalance in the normal stresses, which, in\nturn, drives a collective rearrangement of the cells. This behavior crucially\nrelies on the colony's solid-like mechanical response at short time scales and\ncan be recovered within the framework of active hydrodynamics upon modeling\nbacterial colonies as growing viscoelastic gels characterized by Maxwell-like\nstress relaxation.",
        "positive": "Computer simulation of the phase diagram for a fluid confined in a\n  fractal and disordered porous material: We present a grand canonical Monte Carlo simulation study of the phase\ndiagram of a Lennard-Jones fluid adsorbed in a fractal and highly porous\naerogel. The gel environment is generated from an off-lattice diffusion limited\ncluster-cluster aggregation process. Simulations have been performed with the\nmulticanonical ensemble sampling technique. The biased sampling function has\nbeen obtained by histogram reweighting calculations. Comparing the confined and\nthe bulk system liquid-vapor coexistence curves we observe a decrease of both\nthe critical temperature and density in qualitative agreement with experiments\nand other Monte Carlo studies on Lennard-Jones fluids confined in random\nmatrices of spheres. At variance with these numerical studies we do not observe\nupon confinement a peak on the liquid side of the coexistence curve associated\nwith a liquid-liquid phase coexistence. In our case only a shouldering of the\ncoexistence curve appears upon confinement. This shoulder can be associated\nwith high density fluctuations in the liquid phase. The coexisting vapor and\nliquid phases in our system show a high degree of spatial disorder and\ninhomogeneity."
    },
    {
        "anchor": "Stimuli-responsive twist actuators made from soft elastic composite\n  materials -- linking mesoscopic and macroscopic descriptions: Very recently, the construction of twist actuators from magnetorheological\ngels and elastomers has been suggested. These materials consist of magnetizable\ncolloidal particles embedded in a soft elastic polymeric environment. The twist\nactuation is enabled by a net chirality of the internal particle arrangement.\nUpon magnetization by a homogeneous external magnetic field, the systems\nfeature an overall torsional deformation around the magnetization direction.\nStarting from a discrete minimal mesoscopic model set-up we work towards a\nmacroscopic characterization. The two scales are linked by identifying\nexpressions for the macroscopic system parameters as functions of the\nmesoscopic model parameters. In this way, the observed behavior of a\nmacroscopic system can in principle be mapped to and illustratively be\nunderstood from an appropriate mesoscopic picture. Our results apply equally\nwell to corresponding soft electrorheological gels and elastomers.",
        "positive": "Level-dynamic approach to the excited spectra of the Jahn-Teller model -\n  kink-train lattice and 'glassy' quantum phase: The dynamics of excited phonon spectra of the Exe Jahn-Teller (hereafter, JT)\nmodel mapped onto the generalized Calogero-Moser (gCM) gas of pseudoparticles\nimplies a complex interplay between nonlinearity and fluctuations of\nquasiparticle trajectories. A broad crossover appears in a pseudotime\n(interaction strength) between the initial oscillator region and the nonlinear\nregion of the kink-train lattice as a superlattice of the kink-antikink gCM\ntrajectories. The local nonlinear fluctuations, nuclei (droplets) of the\ngrowing kink phase arise at the crossover, forming a new intermediate droplet\n\"glassy\" phase as a precursor of the kink phase. The \"glassy\" phase is related\nto a broad maximum in the entropy of the probability distributions of\npseudoparticle accelerations, or level curvatures. The kink-train lattice phase\nwith multiple kink-antikink collisions is stabilised by long-range correlations\nwhen approaching a semiclassical limit. A series of bifurcations of\nnearest-level spacings were recognised as signatures of pre-chaotic behaviour\nat the quantum level in the kink phase. Statistical characteristics can be seen\nto confirm the coexistence within all of the spectra of both regularity and\nchaoticity to a varying extent (nonuniversality). Regions are observed within\nwhich one of the phases is dominant."
    },
    {
        "anchor": "Simulation of surfactant transport during the rheological relaxation of\n  two-dimensional dry foams: We describe a numerical model to predict the rheology of two-dimensional dry\nfoams. The model accurately describes soap film curvature, viscous friction\nwith the walls, and includes the transport of surfactant within the films and\nacross the vertices where films meet. It accommodates the changes in foam\ntopology that occur when a foam flows and, in particular, accurately represents\nthe relaxation of the foam following a topological change. The model is\nvalidated against experimental data, allowing the prediction of elastic and\nviscous parameters associated with different surfactant solutions.",
        "positive": "Reciprocal locomotion of dense swimmers in Stokes flow: Due to the kinematic reversibility of Stokes flow, a body executing a\nreciprocal motion (a motion in which the sequence of body configurations\nremains identical under time reversal) cannot propel itself in a viscous fluid\nin the limit of negligible inertia; this result is known as Purcell's scallop\ntheorem. In this limit, the Reynolds numbers based on the fluid inertia and on\nthe body inertia are all zero. Previous studies characterized the breakdown of\nthe scallop theorem with fluid inertia. In this paper we show that, even in the\nabsence of fluid inertia, certain dense bodies undergoing reciprocal motion are\nable to swim. Using Lorentz's reciprocal theorem, we first derive the general\ndifferential equations that govern the locomotion kinematics of a dense\nswimmer. We demonstrate that no reciprocal swimming is possible if the body\nmotion consists only of tangential surface deformation (squirming). We then\napply our general formulation to compute the locomotion of four simple\nswimmers, each with a different spatial asymmetry, that perform normal surface\ndeformations. We show that the resulting swimming speeds (or rotation rates)\nscale as the first power of a properly defined \"swimmer Reynolds number'',\ndemonstrating thereby a continuous breakdown of the scallop theorem with body\ninertia."
    },
    {
        "anchor": "Virial coefficients, thermodynamic properties, and fluid-fluid\n  transition of nonadditive hard-sphere mixtures: Different theoretical approaches for the thermodynamic properties and the\nequation of state for multicomponent mixtures of nonadditive hard spheres in\n$d$ dimensions are presented in a unified way. These include the theory by\nHamad, our previous formulation, the original MIX1 theory, a recently proposed\nmodified MIX1 theory, as well as a nonlinear extension of the MIX1 theory\nproposed in this paper. Explicit expressions for the compressibility factor,\nHelmholtz free energy, and second, third, and fourth virial coefficients are\nprovided. A comparison is carried out with recent Monte Carlo data for the\nvirial coefficients of asymmetric mixtures and with available simulation data\nfor the compressibility factor, the critical consolute point, and the\nliquid-liquid coexistence curves. The merits and limitations of each theory are\npointed out.",
        "positive": "Collective treadmilling in fire ant rafts permits sustained protrusion\n  growth: Condensed active matter is exemplary for its capacity to morph and exhibit\ninternal flows despite remaining cohered. To facilitate understanding of this\nability, we investigate the cause of finger-like protrusions that emerge from\nsuper-organismal, aggregated rafts of fire ants (Solenopsis invicta). While\nthese features are easily observed, what permits their recuring initiation,\ngrowth, and recession is not immediately clear. Ants rafts are comprised of a\nfloating, structural network of interconnected ants on which a layer of freely\nactive ants walks. We show here that sustained shape evolution is permitted by\ntreadmilling defined by the competition between perpetual raft contraction due\nto displacement of bulk structural ants into the active layer, and outwards\nraft expansion due to deposition of free ants into the structural network at\nthe edges. Furthermore, we see that protrusions emerge due to asymmetries in\nthe edge deposition rate of surface ants, and we provide strong evidence that\nthese asymmetries occur stochastically due to wall accumulation effects and\nlocal alignment interactions. Together these effects permit the cooperative,\nyet spontaneous formation of protrusions that fire ants utilize for functional\nexploration and to escape flooded environments. Ant raft dynamics mirror the\ntreadmilling that facilitates morphogenesis and motility of cytoskeletons, thus\nproviding another example in which reshaping of condensed active matter is\nexplained by free constituent transport, yet whose continuance relies on\nperpetual phase transition between structural and free members."
    },
    {
        "anchor": "Dehydration, Dissolution and Melting of Cyclodextrin Crystals: Cyclodextrins are a family of oligosaccharides with a toroid shape which\nexhibit a unique ability of entrapping guest molecules in their internal\ncavity. Water is the primary guest molecule and is omnipresent in the\ncrystalline phases stabilizing the overall architecture. Despite the presence\nof water molecules inside the cavity, cyclodextrins provide a hydrophobic\nenvironment where poorly soluble molecules can easily fit. In this\ninvestigation we put in evidence different types of water in the hydrated\n{\\alpha} , \\b{eta} and {\\gamma} cyclodextrin crystals. Thermogravimetric\nmeasurements identify various binding sites of water and highlight the\ndifference between the crystals equilibrated under various humid atmospheres.\nWe establish by microcalorimetry the limit of solubility versus temperature and\nmeasure for the first time the melting temperatures of the hydrated crystals.\nDissolution and melting enthalpies are derived and the solubility curves are\ncompared to existing literature. The specific features of each cyclodextrin are\nunderlined.",
        "positive": "Structure of Water at Hydrophilic and Hydrophobic Interfaces: Raman\n  Spectroscopy of Water Confined in Periodic Mesoporous (Organo)Silicas: The temperature dependence of the structure of water confined in hydrophilic\nmesostructured porous silica (MCM-41) and hydrophobic benzene-bridged periodic\nmesoporous organosilicas (PMO) is studied by Raman vibrational spectroscopy.\nFor capillary filled pores (75% relative humidity, RH), the OH-stretching\nregion is dominated by the contribution from liquid water situated in the core\npart of the pore. It adopts a bulk-like structure that is modestly disrupted by\nconfinement and surface hydrophobicity. For partially filled pores (33% RH),\nthe structure of the non-freezable adsorbed film radically differs from that\nfound in capillary filled pores. A first remarkable feature is the absence of\nthe Raman spectral fingerprint of low density amorphous ice, even at low\ntemperature (-120{\\textdegree}C). Secondly, additional bands reveal water\nhydroxyls groups pointing towards the different water/solid and water/vapor\ninterfaces. For MCM-41, they correspond to water molecules acting as weak\nH-bond donors with silica, and dangling hydroxyl groups oriented towards the\nempty center of the pore. For benzene-bridged PMO, we found an additional type\nof dangling hydroxyl groups, which we attribute to water at hydrophobic solid\ninterface."
    },
    {
        "anchor": "Percolation through Voids around Toroidal Inclusions: In the case of media comprised of impermeable particles, fluid flows through\nvoids around impenetrable grains. For sufficiently low concentrations of the\nlatter, spaces around grains join to allow transport on macroscopic scales,\nwhereas greater impenetrable inclusion densities disrupt void networks and\nblock macroscopic fluid flow. A critical grain concentration $\\rho_{c}$ marks\nthe percolation transition or phase boundary separating these two regimes. With\na dynamical infiltration technique in which virtual tracer particles explore\nvoid spaces, we calculate critical grain concentrations for randomly placed\ninterpenetrating impermeable toroidal inclusions; the latter consist of\nsurfaces of revolution with circular and square cross sections. In this manner,\nwe study for the first time continuum percolation transitions involving\nnon-convex grains. As the radius of revolution increases relative to the length\nscale of the torus cross section, the tori develop a central hole, a\ntopological transition accompanied by a cusp in the critical porosity for\npercolation. With a further increase in the radius of revolution, as\nconstituent grains become more ring-like in appearance, we find that the\ncritical porosity converges to that of high aspect ratio cylindrical\ncounterparts only for randomly oriented grains.",
        "positive": "The probability distribution of the average relative distance between\n  two points in a dynamical chain: Subject of this letter is the dynamics of a chain obtained performing the\ncontinuous limit of a system of links and beads. In particular, the probability\ndistribution of the relative position between two points of the chain averaged\nover a given interval of time is computed. The physical meaning of the obtained\nresult is investigated in the limiting case of a stiff chain."
    },
    {
        "anchor": "Anisotropic active Brownian particle with a fluctuating propulsion force: The active Brownian particle (ABP) model describes a swimmer, synthetic or\nliving, whose direction of swimming is a Brownian motion. The swimming is due\nto a propulsion force, and the fluctuations are typically thermal in origin. We\npresent a 2D model where the fluctuations arise from nonthermal noise in a\npropelling force acting at a single point, such as that due to a flagellum. We\ntake the overdamped limit and find several modifications to the traditional ABP\nmodel. Since the fluctuating force causes a fluctuating torque, the diffusion\ntensor describing the process has a coupling between translational and\nrotational degrees of freedom. An anisotropic particle also exhibits a\nmass-dependent noise-induced drift, which does not disappear in the overdamped\nlimit. We show that these effects have measurable consequences for the\nlong-time diffusivity of active particles, in particular adding a contribution\nthat is independent of where the force acts.",
        "positive": "An improved kinetic Monte Carlo approach for epitaxial submonolayer\n  growth: Two-component submonolayer growth on triangular lattice is qualitatively\nstudied by kinetic Monte Carlo techniques. The hopping barrier governing\nsurface diffusion of the atoms is estimated with an improved formula and using\nrealistic pair interaction potentials. Realistic degrees of freedoms enhancing\nthe surface diffusion of atoms are also introduced. The main advantages of the\npresented technique are the reduced number of free parameters and the clear\ndiffusion activated mechanism for the segregation of different types of atoms.\nThe potential of this method is exemplified by reproducing (i) vacancy and\nstacking fault related phase-boundary creation and dynamics; (ii) a special\nco-deposition and segregation process where the segregated atoms of the second\ncomponent surrounds the islands formed by the first type of atoms."
    },
    {
        "anchor": "Extensional Viscosity of Immiscible Polymers Multinanolayer Films:\n  Signature of the Interphase: The measurement of interfacial mechanical or rheological properties in\npolymer blends is a challenging task, as well as providing a quantitative link\nbetween these properties and the interfacial nanostructure. Here, we perform a\nsystematic study of the extensional rheology of multilayer films of an\nimmsicible polymer pair, polystyrene and poly(methyl methacrylate). We take\nadvantage of multinanolayer coextrusion to increase the number of interfaces up\nto thousands, consequently magnifying the interfacial response of the films.\nThe transient elongational response is compared to an addivity rule model based\non the summation of the contribution of each polymer as well as the interfacial\none. At low strain rates, the model reproduces the transient extensional\nviscosity up to strain-thinning, while at larger ones, the extra stress exceeds\nthe prediction based on constant interfacial tension. This extra-contribution\nis attributed to an interphase modulus on the order of 1-10 MPa, which\nincreases with strain rate following a power-law with an exponent 1/3.\nExtensional rheology of multinanolayer films is then an efficient combination\nto go beyond interfacial tension and measure quantitatively the interfacial\nrheology of immiscible polymer blends.",
        "positive": "Suppression and emergence of granular segregation under cyclic shear: While convective flows are implicated in many granular segregation processes,\nthe associated particle-scale rearrangements are not well understood. A\nthree-dimensional bidisperse mixture segregates under steady shear, but the\ncyclically driven system either remains mixed or segregates slowly. Individual\ngrain motion shows no signs of particle-scale segregation dynamics that precede\nbulk segregation. Instead, we find that the transition from non-segregating to\nsegregating flow is accompanied by significantly less reversible particle\ntrajectories, and the emergence of a convective flow field."
    },
    {
        "anchor": "Cooperative behavior of molecular motions giving rise to two glass\n  transitions in the same supercooled mesophase of a smectogenic odd liquid\n  crystal dimer: In the present work, a detailed analysis of the glassy behavior and the\nrelaxation dynamics of the liquid crystal dimer\n{\\alpha}-(4-cyanobiphenyl-4'-yloxy)-{\\omega}-(1-pyrenimine-benzylidene-4'-oxy)\nheptane (CBO7O.Py) throughout both nematic and smectic A mesophases by means of\nbroadband dielectric spectroscopy has been performed. CBO7O.Py shows three\ndifferent dielectric relaxation modes and two glass transition (Tg)\ntemperatures: the higher Tg is due to the freezing of the molecular motions\nresponsible of the relaxation mode with the lowest frequency (\\mu 1L); the\nlower Tg is due to the motions responsible of the two relaxation modes with\nhighest frequencies (\\mu 1H and \\mu 2), which converge just at their\ncorresponding Tg. It is shown how the three modes follow a critical-like\ndescription via the dynamic scaling model. The two modes with lowest\nfrequencies (\\mu 1L and \\mu 1H) are cooperative in the whole range of the\nmesophases, whereas the highest frequency mode (\\mu 2) is cooperative just\nbelow some cross-over temperature. In terms of fragility, at the glass\ntransition, the ensemble (\\mu 1H +\\mu 2) presents a value of the steepness\nindex and \\mu 1L a different one, meaning that fragility is a property\nintrinsic of the molecular motion itself. Finally, the steepness index seem to\nhave a universal behavior with temperature for the dielectric relaxation modes\nof liquid crystal dimers, being almost constant at high temperatures and\nincreasing drastically when cooling the compound down to the glass transition\nfrom a temperature about (3/4)TNI.",
        "positive": "Anisotropic molecular diffusion in confinement II: A model for\n  structurally complex particles applied to transport in thin ionic liquid\n  films: Hypothesis:Diffusion in confinement is an important fundamental problem with\nsignificant implications for applications of supported liquid phases. However,\nresolving the spatially dependent diffusion coefficient, parallel and\nperpendicular to interfaces, has been a standing issue and for objects of\nnanometric size, which structurally fluctuate on a similar time scale as they\ndiffuse, no methodology has been established so far. We hypothesise that the\ncomplex, coupled dynamics can be captured and analysed by using a model built\non the $2$-dimensional Smoluchowski equation and systematic coarse-graining.\n  Methods and simulations: For large, flexible species, a universal approach is\noffered that does not make any assumptions about the separation of time scales\nbetween translation and other degrees of freedom. The method is validated on\nMolecular Dynamics simulations of bulk systems of a family of ionic liquids\nwith increasing cation sizes where internal degrees of freedom have little to\nmajor effects.\n  Findings: After validation on bulk liquids, where we provide an\ninterpretation of two diffusion constants for each species found\nexperimentally, we clearly demonstrate the anisotropic nature of diffusion\ncoefficients at interfaces. Spatial variations in the diffusivities relate to\ninterface-induced structuring of the ionic liquids. Notably, the length scales\nin strongly confined ionic liquids vary consistently but differently at the\nsolid-liquid and liquid-vapour interfaces."
    },
    {
        "anchor": "Multicomponent fluid of nonadditive hard spheres near a wall: A recently proposed rational-function approximation [Phys. Rev. E\n\\textbf{84}, 041201 (2011)] for the structural properties of nonadditive hard\nspheres is applied to evaluate analytically (in Laplace space) the local\ndensity profiles of multicomponent nonadditive hard-sphere mixtures near a\nplanar nonadditive hard wall. The theory is assessed by comparison with $NVT$\nMonte Carlo simulations of binary mixtures with a size ratio 1:3 in three\npossible scenarios: a mixture with either positive or negative nonadditivity\nnear an additive wall, an additive mixture with a nonadditive wall, and a\nnonadditive mixture with a nonadditive wall. It is observed that, while the\ntheory tends to underestimate the local densities at contact (especially in the\ncase of the big spheres) it captures very well the initial decay of the\ndensities with increasing separation from the wall and the subsequent\noscillations.",
        "positive": "Particle sizing for flowing colloidal suspensions using\n  flow-differential dynamic microscopy: Particle size is a key variable in understanding the behaviour of the\nparticulate products that underpin much of our modern lives. Typically obtained\nfrom suspensions at rest, measuring the particle size under flowing conditions\nwould enable advances for in-line testing during manufacture and\nhigh-throughput testing during development. However, samples are often turbid,\nmultiply scattering light and preventing the direct use of common sizing\ntechniques. Differential dynamic microscopy (DDM) is a powerful technique for\nanalysing video microscopy of such samples, measuring diffusion and hence\nparticle size without the need to resolve individual particles while free of\nsubstantial user input. However, when applying DDM to a flowing sample,\ndiffusive dynamics are rapidly dominated by flow effects, preventing particle\nsizing. Here, we develop \"flow-DDM\", a novel analysis scheme that combines\noptimised imaging conditions, a drift-velocity correction and modelling of the\nimpact of flow. Flow-DDM allows a decoupling of flow from diffusive motion that\nfacilitates successful particle size measurements at flow speeds an order of\nmagnitude higher than for DDM. We demonstrate the generality of the technique\nby applying flow-DDM to two separate microscopy methods and flow geometries."
    },
    {
        "anchor": "Theory of elementary excitations in unstable Bose-Einstein condensates: Like classical fluids, quantum gases may suffer from hydrodynamic\ninstabilities. Our paper develops a quantum version of the classical stability\nanalysis in fluids, the Bogoliubov theory of elementary excitations in unstable\nBose-Einstein condensates. In unstable condensates the excitation modes have\ncomplex frequencies. We derive the normalization conditions for unstable modes\nsuch that they can serve in a mode decomposition of the non-condensed\ncomponent. Furthermore, we develop approximative techniques to determine the\nspectrum and the mode functions. Finally, we apply our theory to a sonic white\nhole and find that the spectrum of unstable modes is intrinsically discrete.",
        "positive": "Equilibrium configurations of director in a planar nematic cell with one\n  spatially modulated surface: We study two-dimensional equilibrium configurations of nematic liquid crystal\n(NLC) director in a cell confined between two parallel surfaces: a planar\nsurface and a spatially modulated one. The relief of the modulated surface is\ndescribed by a smooth periodic sine-like function. The director easy axis\norientation is homeotropic at one of the bounding surfaces and is planar at the\nother one. Strong NLC anchoring with both surfaces is assumed. We consider the\ncase where disclination lines occur in the bulk of NLC strictly above local\nextrema of the modulated surface. These disclination lines run along the crests\nand troughs of the relief waves. In the approximation of planar director\ndeformations we obtain analytical expressions describing a director\ndistribution in the bulk of the cell. Equilibrium distances from disclination\nlines to the modulated surface are calculated and their dependences on the cell\nthickness and the period and depth of the surface relief are studied. It is\nshown that the distances from disclination lines to the modulated surface\ndecrease as the depth of the relief increases."
    },
    {
        "anchor": "Simultaneous memory effects in the stress and in the dielectric\n  susceptibility of a stretched polymer glass: We report experimental evidence that a polymer stretched at constant strain\nrate $\\dot\\lambda$ presents complex memory effects after that $\\dot\\lambda$ is\nset to zero at a specific strain $\\lambda_w$ for a duration $t_w$, ranging from\n$100$s to $ 2.2\\times10^5$s. When the strain rate is resumed, both the stress\nand the dielectric constant relax to the unperturbed state non monotonically.\nThe relaxations depend on the observable, on $\\lambda_w$ and on $t_w$.\nRelaxation master curves are obtained by scaling the relaxation time as $t/\\ln\n(t_w)$. The dielectric evolution also captures the distribution of the\nrelaxation times, so the results impose strong constraints on the relaxation\nmodels of polymers under stress and they can be useful for a better\nunderstanding of memory effects in other disorder materials.",
        "positive": "Estimating random close packing in polydisperse and bidisperse hard\n  spheres via an equilibrium model of crowding: We show that an analogy between crowding in fluid and jammed phases of hard\nspheres captures the density dependence of the kissing number for a family of\nnumerically generated jammed states. We extend this analogy to jams of mixtures\nof hard spheres in $d=3$ dimensions, and thus obtain an estimate of the random\nclose packing (RCP) volume fraction, $\\phi_{\\textrm{RCP}}$, as a function of\nsize polydispersity. We first consider mixtures of particle sizes with discrete\ndistributions. For binary systems, we show agreement between our predictions\nand simulations, using both our own and results reported in previous works, as\nwell as agreement with recent experiments from the literature. We then apply\nour approach to systems with continuous polydispersity, using three different\nparticle size distributions, namely the log-normal, Gamma, and truncated\npower-law distributions. In all cases, we observe agreement between our\ntheoretical findings and numerical results up to rather large polydispersities\nfor all particle size distributions, when using as reference our own\nsimulations and results from the literature. In particular, we find\n$\\phi_{\\textrm{RCP}}$ to increase monotonically with the relative standard\ndeviation, $s_{\\sigma}$, of the distribution, and to saturate at a value that\nalways remains below 1. A perturbative expansion yields a closed-form\nexpression for $\\phi_{\\textrm{RCP}}$ that quantitatively captures a\ndistribution-independent regime for $s_{\\sigma} < 0.5$. Beyond that regime, we\nshow that the gradual loss in agreement is tied to the growth of the skewness\nof size distributions."
    },
    {
        "anchor": "Heat Capacity Effects Associated with the Hydrophobic Hydration and\n  Interaction of Simple Solutes: A Detailed Structural and Energetical Analysis\n  Based on MD Simulations: We examine the SPCE and TIP5P water models to study heat capacity effects\nassociated with the hydrophobic hydration and interaction of Xenon particles.\nWe calculate the excess chemical potential for Xenon employing the Widom\nparticle insertion technique. The solvation enthalpy and excess heat capacity\nis obtained from the temperature dependence of the chemical potentials and,\nalternatively, directly by Ewald summation, as well as a reaction field based\nmethod. All three different approaches provide consistent results. The reaction\nfield method allows a separation of the individual components to the heat\ncapacity of solvation into solute/solvent and solvent/solvent parts, revealing\nthe solvent/solvent part as the dominating contribution. A detailed spacial\nanalysis of the heat capacity of the water molecules around a pair of Xenon\nparticles at different separations reveals that the enhanced heat capacity of\nthe water molecules in the bisector plane between two Xenon atoms is\nresponsible for the maximum of the heat capacity observed at the desolvation\nbarrier, recently reported by Shimizu and Chan ({\\em J. Am. Chem. Soc.},{\\bf\n123}, 2083--2084 (2001)). The about 60% enlarged heat capacity of water in the\nconcave part of the joint Xenon-Xenon hydration shell is the result of a\ncounterplay of strengthened hydrogen bonds and an enhanced breaking of hydrogen\nbonds with increasing temperature. Differences between the two models\nconcerning the heat capacity in the Xenon-Xenon contact state are attributed to\nthe different water model bulk heat capacities, and to the different spacial\nextension of the structure effect introduced by the hydrophobic particles.\nSimilarities between the different states of water in the joint Xenon-Xenon\nhydration shell and the properties of stretched water are discussed.",
        "positive": "Reply to Comment on \"Influence of Noise on Force Measurements\"\n  [1012.5371]: Having a priori knowledge of the force acting on a noisy system it is\npossible to solve the issue relative to the interpretation of multiplicative\nnoise terms (aka Ito-Stratonovich dilemma). We experimentally show that for a\nBrownian particle the anti-Ito convention is correct. This permits us to\nreconcile force measurements based on the equilibrium distribution and on the\ndrift velocity of a Brownian particle in a diffusion gradient."
    },
    {
        "anchor": "Plasmonic complex fluids of nematiclike and helicoidal self-assemblies\n  of gold nanorods with a negative order parameter: We describe a soft matter system of self-organized oblate micelles and\nplasmonic gold nanorods that exhibit a negative orientational order parameter.\nBecause of anisotropic surface anchoring interactions, colloidal gold nanorods\ntend to align perpendicular to the director describing the average orientation\nof normals to the discoidal micelles. Helicoidal structures of highly\nconcentrated nanorods with a negative order parameter are realized by adding a\nchiral additive and are further controlled by means of confinement and\nmechanical stress. Polarization-sensitive absorption, scattering, and\ntwo-photon luminescence are used to characterize orientations and spatial\ndistributions of nanorods. Self-alignment and effective-medium optical\nproperties of these hybrid inorganic-organic complex fluids match predictions\nof a simple model based on anisotropic surface anchoring interactions of\nnanorods with the structured host medium.",
        "positive": "Random sequential adsorption of spheres on a cylinder: Inspired by observations of beads packed on a thin string in such systems as\nsea-grapes and dental plaque, we study the random sequential adsorption of\nspheres on a cylinder. We determine the asymptotic fractional coverage of the\ncylinder as a function of the sole parameter in the problem, the ratio of the\nsphere radius to the cylinder radius (for a very long cylinder) using a\ncombination of analysis and numerical simulations. Examining the asymptotic\nstructures, we find weak chiral ordering on sufficiently small spatial scales.\nExperiments involving colloidal microspheres that can attach irreversibly to a\nsilica wire via electrostatic forces or DNA hybridization allow us to verify\nour predictions for the asymptotic coverage."
    },
    {
        "anchor": "Acoustically levitated lock and key grains: We present a scheme for generating shape-dependent, specific bonds between\nmillimeter scale particles, using acoustic levitation. We levitate particles in\nan ultrasonic standing wave, allowing for substrate-free assembly. Secondary\nscattering generates shape-dependent attractive forces between particles, while\ndriving the acoustic trap above its resonance frequency produces active\nfluctuations that mimic an effective temperature. We 3D print planar particles,\nand show that the local curvature of their binding sites controls the\nselectivity for attaching a matching particle. We find that the bound-state\nprobability and bound-state lifetime can be independently tuned via the binding\nsite depth and height respectively. Finally, we show that these principles can\nbe used to design particles that assemble into complex structures.",
        "positive": "Superconducting transition temperature in thin films: By considering the Ginzburg-Landau model, compactified in one of the spatial\ndimensions, and using a modified Matsubara formalism, we determine the\ndependence of the superconducting transition temperature (T_c) of a film as a\nfunction of its thickness (L). We show that T_c is a decreasing linear function\nof L^{-1}, as has been found experimentally. The critical thickness for the\nsuppression of superconductivity is expressed in terms of the Ginzburg-Landau\nparameters."
    },
    {
        "anchor": "Spiraling Defect Cores in Chromonic Hedgehogs: An elastic quartic twist theory has recently been proposed for chromonic\nliquid crystals, intended to overcome the paradoxical conclusions encountered\nby the classical Oseen-Frank theory when applied to droplets submerged in an\nisotropic fluid environment. However, available experimental data for\nchromonics confined to cylindrical cavities with degenerate planar anchoring on\ntheir lateral boundary can be explained equally well by both competing\ntheories. This paper identifies a means to differentiate these theories both\nqualitatively and quantitatively. They are shown to predict quite different\ncore defects for the twisted hedgehogs that chromonics generate when confined\nto a fixed spherical cavity with homeotropic anchoring. In the quartic twist\ntheory, the defect core is estimated to be nearly one order of magnitude larger\n(tens of microns) than in the other and, correspondingly, the director field\nlines describe Archimedean spirals instead of logarithmic ones.",
        "positive": "Energy barriers govern glassy dynamics in tissues: Recent observations demonstrate that densely packed tissues exhibit features\nof glassy dynamics, such as caging behavior and dynamical heterogeneities,\nalthough it has remained unclear how single-cell properties control this\nbehavior. Here we develop numerical and theoretical models to calculate energy\nbarriers to cell rearrangements, which help govern cell migration in cell\nmonolayers. In contrast to work on sheared foams, we find that energy barrier\nheights are exponentially distributed and depend systematically on the cell's\nnumber of neighbors. Based on these results, we predict glassy two-time\ncorrelation functions for cell motion, with a timescale that increases rapidly\nas cell activity decreases. These correlation functions are used to construct\nsimple random walks that reproduce the caging behavior observed for cell\ntrajectories in experiments. This work provides a theoretical framework for\npredicting collective motion of cells in wound-healing, embryogenesis and\ncancer tumorigenesis."
    },
    {
        "anchor": "Active dry granular flows: rheology and rigidity transitions: The constitutive relations of a dense granular flow composed of\nself-propelling frictional hard particles are investigated by means of DEM\nnumerical simulations. We show that the rheology, which relates the dynamical\nfriction $\\mu$ and the volume fraction $\\phi$ to the inertial number $I$,\ndepends on a dimensionless number $\\mathcal{A}$, which compares the active\nforce to the confining pressure. Two liquid/solid transitions -- in the Maxwell\nrigidity sense -- are observed. As soon as the activity is turned on, the\npacking becomes an `active solid' with a mean number of particle contacts\nlarger than the isostatic value. The quasi-static values of $\\mu$ and $\\phi$\ndecrease with $\\mathcal{A}$. At a finite value of the activity $\\mathcal{A}_t$,\ncorresponding to the isostatic condition, a second `active rigidity transition'\nis observed beyond which the quasi-static values of the friction vanishes and\nthe rheology becomes Newtonian. For $\\mathcal{A}>\\mathcal{A}_t$, we provide\nevidence for a highly intermittent dynamics of this 'active fluid'.",
        "positive": "Direct verification of the fluctuation-dissipation relation in viscously\n  coupled oscillators: The fluctuation-dissipation relation, a central result in non-equilibrium\nstatistical physics, relates equilibrium fluctuations in a system to its linear\nresponse to external forces. Here we provide a direct experimental verification\nof this relation for viscously coupled oscillators, as realized by a pair of\noptically trapped colloidal particles. A theoretical analysis, in which\ninteractions mediated by slow viscous flow are represented by non-local\nfriction tensors, matches experimental results and reveals a frequency maximum\nin the amplitude of the mutual response which is a sensitive function of the\ntrap stiffnesses and the friction tensors. This allows for its location and\nwidth to be tuned and suggests the utility of the trap setup for accurate\ntwo-point microrheology."
    },
    {
        "anchor": "NMR Studies on the Temperature-Dependent Dynamics of Confined Water: We use $^2$H NMR to study the rotational motion of supercooled water in\nsilica pores of various diameters, specifically, in the MCM-41 materials C10,\nC12, and C14. Combination of spin-lattice relaxation, line-shape, and\nstimulated-echo analyses allows us to determine correlation times in very broad\ntime and temperature ranges. For the studied pore diameters, 2.1-2.9 nm, we\nfind two crossovers in the temperature-dependent correlation times of liquid\nwater upon cooling. At 220-230 K, a first kink in the temperature dependence is\naccompanied by a solidification of a fraction of the confined water, implying\nthat the observed crossover is due to a change from bulk-like to\ninterface-dominated water dynamics, rather than to a liquid-liquid phase\ntransition. Moreover, the results provide evidence that $\\alpha$ process-like\ndynamics is probed above the crossover temperature, whereas $\\beta$\nprocess-like dynamics is observed below. At 180-190 K, we find a second change\nof the temperature dependence, which resembles that reported for the $\\beta$\nprocess of supercooled liquids during the glass transition, suggesting a value\nof $T_g\\!\\approx\\!185$ K for interface-affected liquid water. In the\nhigh-temperature range, $T\\!>\\!225$ K, the temperature dependence of water\nreorientation is weaker in the smaller C10 pores than in the larger C12 and C14\npores, where it is more bulk-like, indicating a significant effect of the\nsilica confinement on the $\\alpha$ process of water in the former 2.1 nm\nconfinement. By contrast, the temperature dependence of water reorientation is\nlargely independent of the confinement size and described by an Arrhenius law\nwith an activation energy of $E_a\\!\\approx\\!0.5\\ $eV in the low-temperature\nrange, $T\\!<\\!180 $K, revealing that the confinement size plays a minor role\nfor the $\\beta$ process of water.",
        "positive": "Expansion of a coherent array of Bose-Einstein condensates: We investigate the properties of a coherent array containing about 200\nBose-Einstein condensates produced in a far detuned 1D optical lattice. The\ndensity profile of the gas, imaged after releasing the trap, provides\ninformation about the coherence of the ground-state wavefunction. The measured\natomic distribution is characterized by interference peaks. The time evolution\nof the peaks, their relative population as well as the radial size of the\nexpanding cloud are in good agreement with the predictions of theory. The 2D\nnature of the trapped condensates and the conditions required to observe the\neffects of coherence are also discussed."
    },
    {
        "anchor": "Topology-induced confined superfluidity in inhomogeneous arrays: We report the first study of the zero-temperature phase diagram of the\nBose-Hubbard model on topologically inhomogeneous arrays. We show that the\nusual Mott-insulator and superfluid domains, in the paradigmatic case of the\ncomb lattice, are separated by regions where the superfluid behaviour of the\nbosonic system is confined along the comb backbone. The existence of such {\\it\nconfined superfluidity}, arising from topological inhomogeneity, is proved by\ndifferent analytical and numerical techniques which we extend to the case of\ninhomogeneous arrays. We also discuss the relevance of our results to real\nsystem exhibiting macroscopic phase coherence, such as coupled Bose condensates\nand Josephson arrays.",
        "positive": "Nonlinear acoustic wave generation in a three-phase seabed: Generation of an acoustic wave by two pump sound waves is studied in a\nthree-phase marine sediment that consists of a solid frame and the pore water\nwith air bubbles in it. To avoid shock-wave formation the interaction is\nconsidered in the frequency range where there is a significant amount of sound\nvelocity dispersion. Nonlinear equations are obtained to describe the\ninteraction of acoustic waves in the presence of air bubbles. An expression for\nthe amplitude of the generated wave is obtained and numerical analysis of its\ndependence on distance and on the resonance frequency of bubbles is performed."
    },
    {
        "anchor": "Mode-Coupling Theory for Active Brownian Particles: We present a mode-coupling theory (MCT) for the high-density dynamics of\ntwo-dimensional spherical active Brownian particles (ABP). The theory is based\non the integration-through-transients (ITT) formalism and hence provides a\nstarting point for the calculation of non-equilibrium averages in\nactive-Brownian particle systems. The ABP are characterized by a\nself-propulsion velocity $v_0$, and by their translational and rotational\ndiffusion coefficients, $D_t$ and $D_r$. The theory treats both the\ntranslational and the orientational degrees of freedom of ABP explicitly. This\nallows to study the effect of self-propulsion of both weak and strong\npersistence of the swimming direction, also at high densities where the\npersistence length $\\ell_p=v_0/D_r$ is large compared to the typical\ninteraction length scale. While the low-density dynamics of ABP is\ncharacterized by a single P\\'eclet number, $Pe=v_0^2/D_rD_t$, close to the\nglass transition the dynamics is found to depend on $Pe$ and $\\ell_p$\nseparately. At fixed density, increasing the self-propulsion velocity causes\nstructural relaxatino to speed up, while decreasing the persistence length\nslows down the relaxation. The theory predicts a non-trivial\nidealized-glass-transition diagram in the three-dimensional parameter space of\ndensity, self-propulsion velocity and rotational diffusivity. The active-MCT\nglass is a nonergodic state where correlations of initial density fluctuations\nnever fully decay, but also an infinite memory of initial orientational\nfluctuations is retained in the positions.",
        "positive": "Post-processing of polymer foam tissue scaffolds with high power\n  ultrasound: a route to increased pore interconnectivity, pore size and fluid\n  transport: We expose thick polymer foam tissue scaffolds to high power ultrasound and\nstudy its effect on the openness of the pore architecture and fluid transport\nthrough the scaffold. Our analysis is supported by measurements of fluid uptake\nduring insonification and imaging of the scaffold microstructure via x-ray\ncomputed tomography, scanning electron microscopy and acoustic microscopy. The\nultrasonic treatment is found to increase the mean pore size by over 10%. More\nstriking is the improvement in fluid uptake: for scaffolds with only 40% water\nuptake via standard immersion techniques, we can routinely achieve full\nsaturation of the scaffold over approximately one hour of exposure. These\ndesirable modifications occur with no loss of scaffold integrity and negligible\nmass loss, and are optimized when the ultrasound treatment is coupled to a\npre-wetting stage with ethanol. Our findings suggest that high power ultrasound\nis a highly targetted and efficient means to promote pore interconnectivity and\nfluid transport in thick foam tissue scaffolds."
    },
    {
        "anchor": "Geometry and elasticity of a knitted fabric: Knitting is not only a mere art and craft hobby but also a thousand year old\ntechnology. Unlike weaving, it can produce loose yet extremely stretchable\nfabrics with almost vanishing rigidity, a desirable property exhibited by\nhardly any bulk material. It also enables the engineering of arbitrarily shaped\ntwo and three-dimensional objects with tunable mechanical response. In contrast\nwith the extensive body of related empirical knowledge and despite a growing\nindustrial interest, the physical ingredients underlying these intriguing\nmechanical properties remain poorly understood. To make some progress in this\ndirection, we study a model tricot made of a single elastic thread knitted into\nthe common pattern called \\textit{stockinette}. On the one hand, we\nexperimentally investigate its tensile response and measure local displacements\nof the stitches during deformation. On the other hand, we derive a\nfirst-principle mechanical model for the displacement field based on the yarn\nbending energy, the conservation of its total length and the topological\nconstraints on the constitutive stitches. Our model solves both the shape and\nmechanical response of the knit and agrees quantitatively with our\nmeasurements. This study thus provides a fundamental framework for the\nunderstanding of knitted fabrics, paving the way to thread-based smart\nmaterials.",
        "positive": "The effective colloid interaction in the Asakura-Oosawa model.\n  Assessment of non-pairwise terms from the virial expansion: The relevance of neglecting three- and four-body interactions in the\ncoarse-grained version of the Asakura-Oosawa model is examined. A mapping\nbetween the first few virial coefficients of the binary nonadditive hard-sphere\nmixture representative of this model and those arising from the coarse-grained\n(pairwise) depletion potential approximation allows for a quantitative\nevaluation of the effect of such interactions. This turns out to be especially\nimportant for large size ratios and large reservoir polymer packing fractions."
    },
    {
        "anchor": "Crystallization kinetics of\n  (S)-4'-(1-methylheptyloxycarbonyl)biphenyl-4-yl\n  4-[4-(2,2,3,3,4,4,4-heptafluorobutoxy)but-1-oxy]-2-fluorobenzoate: Chiral liquid crystalline compounds belonging to the homologous series of\n(S)-4'-(1-methylheptyloxycarbonyl)biphenyl-4-yl\n4-[m-(2,2,3,3,4,4,4-heptafluorobutoxy)alk-1-oxy]-2-fluorobenzoates show various\nbehavior on cooling depending on the length of the CmH2m chain. The homologue\nwith m = 2 crystallizes, while for m = 5, 6, 7, and presumably also for m = 3,\nthe glass of the anticlinic smectic CA* phase is formed. The previous results\nfor m = 4 suggest that this homologue may also be a glassformer. This paper\npresents the study of the crystallization kinetics for the compound with m = 4\nin isothermal conditions (by polarizing optical microscopy) and for the 5-40\nK/min cooling rates (by differential scanning calorimetry). Microscopic\nobservations enable estimation of the energy barrier for nucleation, which\nequals 409 kJ/mol. The threshold cooling rate necessary for complete\nvitrification of the smectic CA* phase, obtained by extrapolating the enthalpy\nchange during crystallization to zero, is equal to 81 K/min or 64 K/min for the\nlinear and parabolic fit, respectively. The structural studies by X-ray\ndiffraction show that crystal phases have lamellar structures both in the\npristine sample and after crystallization from the melt but with different\nlayer spacing. A weak relaxation process is detected in the sample after melt\ncrystallization, revealing the presence of the conformational disorder. The\ndynamic glass transition temperature of the SmCA* phase, estimated from the\nrelaxation time of the PH process (as the {\\alpha}-relaxation time could not be\nregistered in a wide enough temperature range), is 244 K.",
        "positive": "Dynamics of a colloidal glass during stress-mediated structural arrest: We employ parallel superposition rheology to study the dynamics of an aging\ncolloidal glass in the presence of a mean field stress. Over a range of\nintermediate stresses, the loss modulus exceeds the storage modulus at short\ntimes but develops a maximum concomitant with a crossover between the two as\nthe system ages. This is attended by a narrowing of the loss peak on increasing\nstress. We show that this feature is characteristic of the structural arrest in\nthese materials, which is made observable on reasonable timescales by the\nactivating influence of the stress. The arrest time displays an exponential\ndependence on inverse stress. These results provide experimental validation of\nthe role of stress as an effective temperature in soft glassy systems as has\nbeen advanced in recent theoretical frameworks."
    },
    {
        "anchor": "Nonlinear dielectric effect of dipolar fluids: The nonlinear dielectric effect for dipolar fluids is studied within the\nframework of the mean spherical approximation (MSA) of hard core dipolar Yukawa\nfluids. Based on earlier results for the electric field dependence of the\npolarization our analytical results show so-called normal saturation effects\nwhich are in good agreement with corresponding NVT ensemble Monte Carlo\nsimulation data. The linear and the nonlinear dielectric permittivities\nobtained from MC simulations are determined from the fluctuations of the total\ndipole moment of the system in the absence of an applied electric field. We\ncompare the MSA based theoretical results with the corresponding Langevin and\nDebye-Weiss behaviors.",
        "positive": "Excluded Volume Effect in Unzipping DNA with a Force: A double stranded DNA molecule when pulled with a force acting on one end of\nthe molecule can become either partially or completely unzipped depending on\nthe magnitude of the force F. For a random DNA sequence, the number M of\nunzipped base pairs goes as M~(F-Fc)^(-2) and diverges at the critical force Fc\nwith an exponent \\chi=2. We find that when excluded volume effect is taken into\naccount for the unzipped part of the DNA, the exponent \\chi=2 is not changed\nbut the critical force Fc is changed. The force versus temperature phase\ndiagram depends on only two parameters in the model, the persistence length and\nthe denaturation temperature. Furthermore a scaling form of the phase diagram\ncan be found. This scaling form is parameter independent and depends only on\nthe spatial dimension. It applies to all DNA molecules and should provide a\nuseful framework for comparison with experiments."
    },
    {
        "anchor": "Acoustokinetics: Crafting force landscapes from sound waves: Factoring the pressure field of a harmonic sound wave into its amplitude and\nphase profiles provides the foundation for an analytical framework for studying\nacoustic forces that not only provides novel insights into the forces exerted\nby specified sound waves, but also addresses the inverse problem of designing\nsound waves to implement desired force landscapes. We illustrate the benefits\nof this acoustokinetic framework through case studies of purely nonconservative\nforce fields, standing waves, pseudo-standing waves, and tractor beams.",
        "positive": "Solvent coarsening around colloids driven by temperature gradients: Using mesoscopic numerical simulations and analytical theory we investigate\nthe coarsening of the solvent structure around a colloidal particle emerging\nafter a temperature quench of the colloid surface. Qualitative differences in\nthe coarsening mechanisms are found, depending on the composition of the binary\nliquid mixture forming the solvent and on the adsorption preferences of the\ncolloid. For an adsorptionwise neutral colloid, as function of time the phase\nbeing next to its surface alternates. This behavior sets in on the scale of the\nrelaxation time of the solvent and is absent for colloids with strong\nadsorption preferences. A Janus colloid, with a small temperature difference\nbetween its two hemispheres, reveals an asymmetric structure formation and\nsurface enrichment around it, even if the solvent is within its one-phase\nregion and if the temperature of the colloid is above the critical demixing\ntemperature $T_c$ of the solvent. Our phenomenological model turns out to\ncapture recent experimental findings according to which, upon laser\nillumination of a Janus colloid and due to the ensuing temperature gradient\nbetween its two hemispheres, the surrounding binary liquid mixture develops a\nconcentration gradient."
    },
    {
        "anchor": "Local-field distribution in resonant composites: Green's-function\n  formalism: The effective response depends sensitively on composite microstructure due to\nlarge fluctuations in the local electric field. For metallic clusters embedded\nin a dielectric host, the local field distributions are extremely inhomogeneous\nin space around the metallic clusters due to quasi-static resonance, leading to\na large enhancement in the effective linear and nonlinear responses. In this\nwork, we propose a general method for computing the electric field of metallic\nclusters near resonance via a perturbation formalism. We illustrate the method\nby simple examples.",
        "positive": "From Crystals to Disordered Crystals: A Hidden Order-Disorder Transition: We find an order-disorder transition from crystals to disordered crystals for\nstatic packings of frictionless spheres. While the geometric indicators are\nmostly blind to the transition, disordered crystals already exhibit properties\napart from crystals. The transition approaches the close packing of hard\nspheres, giving rise to the singularity of the close packing point. We evidence\nthat both the transition and properties of disordered crystals are jointly\ndetermined by the structural orders and density. Near the transition, the\nelastic moduli and coordination number of disordered crystals show particular\npressure dependence distinct from both crystals and jammed solids."
    },
    {
        "anchor": "Elastic consequences of a single plastic event: towards a realistic\n  account of structural disorder and shear wave propagation in models of\n  flowing amorphous solids: Shear transformations (i.e., localised rearrangements of particles resulting\nin the shear deformation of a small region of the sample) are the building\nblocks of mesoscale models for the flow of disordered solids. In order to\ncompute the time-dependent response of the solid material to such a shear\ntransformation, with a proper account of elastic heterogeneity and shear wave\npropagation, we propose and implement a very simple Finite-Element (FE) -based\nmethod. Molecular Dynamics (MD) simulations of a binary Lennard-Jones glass are\nused as a benchmark for comparison, and information about the microscopic\nviscosity and the local elastic constants is directly extracted from the MD\nsystem and used as input in FE. We find very good agreement between FE and MD\nregarding the temporal evolution of the disorder-averaged displacement field\ninduced by a shear transformation, which turns out to coincide with the\nresponse of a uniform elastic medium. However, fluctuations are relatively\nlarge, and their magnitude is satisfactorily captured by the FE simulations of\nan elastically heterogeneous system. Besides, accounting for elastic anisotropy\non the mesoscale is not crucial in this respect. The proposed method thus paves\nthe way for models of the rheology of amorphous solids which are both\ncomputationally efficient and realistic, in that structural disorder and\ninertial effects are accounted for.",
        "positive": "Critical Velocity of Superfluid Flow past Large Obstacles in\n  Bose-Condensates: By considering the stability of potential flow of a superfluid around large\nobstacles of size R, we derive an analytical result for the critical velocity\nwhich is of order v_c \\sim \\hbar / mR, scaling inversely with obstacle size, in\ncontrast to what is obtained from a Landau criterion. Our results are compared\nwith numerical solutions of the Gross-Pitaevskii equation and with recent\nmeasurements of the critical velocity in Bose-Einstein condensates of dilute\natomic gases."
    },
    {
        "anchor": "X,Y,Z-Waves: Extended Structures in Nonlinear Lattices: Motivated by recent experimental and theoretical results on optical X-waves,\nwe propose a new type of waveforms in 2D and 3D discrete media -- multi-legged\nextended nonlinear structures (ENS), built as arrays of lattice solitons (tiles\nor stones, in the 2D and 3D cases, respectively). First, we study the stability\nof the tiles and stones analytically, and then extend them numerically to\ncomplete ENS forms for both 2D and 3D lattices. The predicted patterns are\nrelevant to a variety of physical settings, such as Bose-Einstein condensates\nin deep optical lattices, lattices built of microresonators, photorefractive\ncrystals with optically induced lattices (in the 2D case) and others.",
        "positive": "Density-induced reentrant melting of colloidal Wigner crystals: Electrostatic repulsions can drive crystallization in many-particle systems.\nFor charged colloidal systems, the phase boundaries as well as crystal\nstructure are highly tunable by experimental parameters such as salt\nconcentration and pH. By using projections of the colloid-ion mixture to a\nsystem of (soft) repulsive spheres and the one-component plasma (OCP), we study\nthe hitherto unexplained experimentally observed reentrant melting of\nelectrostatically repelling colloids upon increasing the colloid density. Our\nstudy shows that the surface chemistry should involve a competition between\nadsorption of cations and anions to explain the observed density-induced\nreentrant melting."
    },
    {
        "anchor": "Stretching helical nano-springs at finite temperature: Using dynamic simulations and analytic methods, we study the elastic response\nof a helical filament subject to uniaxial tension over a wide range of bend and\ntwist persistence length. A low-pitch helix at low temperatures exhibits a\nstretching instability and the force-extension curve consists of a sequence of\nspikes. At elevated temperature (i.e. small persistence lengths) the helix\nmelts and a pronounced force plateau is obtained in the fixed-extension\nensemble. The torque boundary condition significantly affects the resulting\nelastic properties.",
        "positive": "Chloroplasts in plant cells show active glassy behavior under low light\n  conditions: Plants have developed intricate mechanisms to adapt to changing light\nconditions. Besides photo- and helio- tropism -- the differential growth\ntowards light and the diurnal motion with respect to sunlight -- chloroplast\nmotion acts as a fast mechanism to change the intracellular structure of leaf\ncells. While chloroplasts move towards the sides of the plant cell to avoid\nstrong light, they accumulate and spread out into a layer on the bottom of the\ncell at low light to increase the light absorption efficiency. Although the\nmotion of chloroplasts has been studied for over a century, the collective\norganelle-motion leading to light adapting self-organized structures remains\nelusive. Here we study the active motion of chloroplasts under dim light\nconditions, leading to an accumulation in a densely packed quasi-2D layer. We\nobserve burst-like re-arrangements and show that these dynamics resemble\ncolloidal systems close to the glass transition by tracking individual\nchloroplasts. Furthermore, we provide a minimal mathematical model to uncover\nrelevant system parameters controlling the stability of the dense configuration\nof chloroplasts. Our study suggests that the meta-stable caging close to the\nglass-transition in the chloroplast mono-layer serves a physiological\nrelevance. Chloroplasts remain in a spread-out configuration to increase the\nlight uptake, but can easily fluidize when the activity is increased to\nefficiently re-arrange the structure towards an avoidance state. Our research\nopens new questions about the role that dynamical phase transitions could play\nin self-organized intracellular responses of plant cells towards environmental\ncues."
    },
    {
        "anchor": "\"Kohn-Shamification\" of the classical density-functional theory of\n  inhomogeneous polar molecular liquids with application to liquid hydrogen\n  chloride: The Gordian knot of density-functional theories for classical molecular\nliquids remains finding an accurate free-energy functional in terms of the\ndensities of the atomic sites of the molecules. Following Kohn and Sham, we\nshow how to solve this problem by considering noninteracting molecules in a set\nof effective potentials. This shift in perspective leads to an accurate and\ncomputationally tractable description in terms of simple three-dimensional\nfunctions. We also treat both the linear- and saturation- dielectric responses\nof polar systems, presenting liquid hydrogen chloride as a case study.",
        "positive": "Thermal Conductivity of PAAm Hydrogel and its Crosslinking Effect: As the interface between human and machine becomes blurred, hydrogel\nincorporated electronics and devices have emerged to be a new class of\nflexible/stretchable electronic and ionic devices due to their extraordinary\nproperties, such as soft, mechanically robust and biocompatible. However, heat\ndissipation in these devices could be a critical issue and remains unexplored.\nHere, we report the experimental measurements and equilibrium molecular dynamic\n(EMD) simulations of thermal conduction in polyacrylamide (PAAm) hydrogels at\nroom temperature. The thermal conductivity of the PAAm hydrogels can be\nmodulated from 0.33 to 0.51 Wm-1K-1 by changing the crosslinking density. The\ncrosslinking density dependent thermal conductivity in hydrogels is explained\nby the competition between the increased conduction pathways and the enhanced\nphonon scattering effect. The assumption is further supported by both the\nequilibrium swelling ratio measurement and molecular simulation of hydrogels.\nOur study offers fundamental understanding of thermal transport in soft\nmaterials and provides design guidance for hydrogel-based devices."
    },
    {
        "anchor": "Wetting of nanopores probed with pressure: Nanopores are both a tool to study single-molecule biophysics and nanoscale\nion transport, but also a promising material for desalination or osmotic power\ngeneration. Understanding the physics underlying ion transport through\nnano-sized pores allows better design of porous membrane materials. Material\nsurfaces can present hydrophobicity, a property which can make them prone to\nformation of surface nanobubbles. Nanobubbles can influence the electrical\ntransport properties of such devices. We demonstrate an approach which uses\nhydraulic pressure to probe the electrical transport properties of solid state\nnanopores. We show how pressure can be used to wet pores, and how it allows\ncontrol over bubbles in the nanometer scale range normally unachievable using\nonly an electrical driving force. Molybdenum disulfide is then used as a\ntypical example of a 2D material on which we demonstrate wetting and bubble\ninduced nonlinear and linear conductance in the regimes typically used with\nthese experiments. We show that by using pressure one can identify and evade\nwetting artifacts.",
        "positive": "Confinement determines transport of a reaction-diffusion active matter\n  front: Couplings between biochemical and mechanical processes have a profound impact\non embryonic development. However, in-vitro studies capable of quantifying\nthese interactions have remained elusive. Here, we investigate a synthetic\nsystem where a DNA reaction-diffusion (RD) front is advected by a turbulent\nflow generated by active matter (AM) flows in a quasi-one-dimensional geometry.\nWhereas the dynamics of simple RD fronts solely depend on the reaction and\ndiffusion rates, we show that RD-AM front propagation is also influenced by the\nconfinement geometry. We first experimentally dissected the different\ncomponents of the reaction-diffusion-advection process by knocking out reaction\nor advection and observed how RD-AM allows for faster transport over large\ndistances, avoiding dilution. We then show how confinement impacts active\nmatter flow: while changes in instantaneous flow velocities are small;\ncorrelation times are dramatically increased with decreasing confinement. As a\nresult, RD-AM front speed increased 3 to 9-fold compared to a RD one. This\nRD-AM experimental model provides a framework for the rational engineering of\ncomplex spatiotemporal processes observed in living systems. It will reinforce\nour understanding of how macro-scale patterns and structures emerge from\nmicroscopic components in non-equilibrium systems."
    },
    {
        "anchor": "Quasi-binary amorphous phase in a 3D system of particles with\n  repulsive-shoulder interactions: We report a computer-simulation study of the equilibrium phase diagram of a\nthree-dimensional system of particles with a repulsive step potential. Using\nfree-energy calculations, we have determined the equilibrium phase diagram of\nthis system. At low temperatures, we observe a number of distinct crystal\nphases. However, under certain conditions the system undergoes a glass\ntransition in a regime where the liquid appears thermodynamically stable. We\nargue that the appearance of this amorphous low-temperature phase can be\nunderstood by viewing this one-component system as a pseudo-binary mixture.",
        "positive": "Solving the Poisson-Boltzmann Equation to Obtain Interaction Energies\n  Between Confined, Like-charged Cylinders: We numerically solve the non-linear Poisson-Boltzmann equation for two\ncylinders confined by two parallel charged plates. The repulsive electrical\ndouble layer component of the cylinder pair potential is substantially reduced\nby confinement between like-charged plates. While the effective cylinder\nsurface charge is increased by the confinement, the effective interaction\nscreening length is reduced, this effect being dominant so that the repulsive\nconfined cylinder-cylinder interaction potential is reduced."
    },
    {
        "anchor": "Critical adsorption controls translocation of polymer chains through\n  lipid bilayers and permeation of solvent: Monte Carlo simulations using an explicit solvent model indicate a new\npathway for translocation of a polymer chain through a lipid bilayer. We\nconsider a polymer chain composed of repeat units with a given hydrophobicity\nand a coarse-grained model of a lipid bilayer in the self-organized liquid\nstate. By varying the degree of hydrophobicity the chain undergoes an\nadsorption transition with respect to the lipid bilayer. Close to the\ntransition point, at a properly balanced hydrophobicity of the chain, the\nmembrane becomes transparent with respect to the chain. At the same time the\nsolvent permeability of the bilayer is strongly increased in the region close\nto adsorbed chain. Our results indicate that the critical point of adsorption\nof the polymer chain interacting with the fluctuating lipid bilayer could play\na key role for the translocation of molecules though biological membranes.",
        "positive": "Generalized Entropy Theory of Glass Formation in Polymer Melts with\n  Specific Interactions: Chemical structure has been long recognized to greatly influence polymer\nglass formation, but a general molecular theory that predicts how chemical\nstructure determines the properties of glass-forming polymers has been slow to\ndevelop. While the generalized entropy theory (GET) explains the influence of\nvarious molecular details on polymer glass formation, the application of the\nGET has heretofore been limited to the use of the simplest polymer model in\nwhich all united atom groups within the monomers of a species interact with a\ncommon monomer averaged van der Waals energy. However, energetic\nheterogeneities are ubiquitous within the monomers of real polymers, and their\nimplications for polymer glass formation remain to be investigated\ntheoretically. This paper uses an extension of the GET to explore the influence\nof energetic heterogeneities within monomers upon the nature of polymer glass\nformation. The present paper focuses on establishing general trends for the\nvariation of characteristic properties of glass formation, such as the isobaric\nfragility parameter $m_P$ and the glass transition temperature $T_g$, with\nmolecular details, such as the specific interactions and chain stiffness. Our\ncomputations confirm that the previously used model with monomer averaged\ninteractions correctly captures general trends in the variation of $m_P$ and\n$T_g$ with various molecular parameters. More importantly, adjustment of the\nenergetic heterogeneities within monomers alone are shown to provide an\nefficient mechanism for tailoring the properties of glass-forming polymers. The\nvariations of polymer properties along iso-fragility and iso-$T_g$ lines are\nillustrated as important design tools for exhibiting the combined influence of\nspecific interactions and chain stiffness."
    },
    {
        "anchor": "Quantifying material properties of cell monolayers by analyzing integer\n  topological defects: In developing organisms, internal cellular processes generate mechanical\nstresses at the tissue scale. The resulting deformations depend on the material\nproperties of the tissue, which can exhibit long-ranged orientational order and\ntopological defects. It remains a challenge to determine these properties on\nthe time scales relevant for developmental processes. Here, we build on the\nphysics of liquid crystals to determine material parameters of cell monolayers.\nSpecifically, we use a hydrodynamic description to characterize the stationary\nstates of compressible active polar fluids around defects. We illustrate our\napproach by analyzing monolayers of C2C12 cells in small circular confinements,\nwhere they form a single topological defect with integer charge. We find that\nsuch monolayers exert compressive stresses at the defect centers, where\nlocalized cell differentiation and formation of three-dimensional shapes is\nobserved.",
        "positive": "Molecular Dynamics Simulation of Imidazolium CnMIM-BF4 Ionic Liquids\n  using a Coarse Grained Force-Field: Ionic Liquids feature thermophysical properties that are of interest in\nsolvents, energy storage materials and tenable lubrication applications.\nRecently, a series of coarse grained (CG) models was developed to investigate\n1-ethyl-3-methylimidazolium tetrafluoroborate [C2MIM][BF4] and\n1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] ionic liquids.\nBuilding on these CG models we derive force-fields to investigate the\n[C_{2-8}MIM] [BF4] family of ionic liquids, as a starting step for systematic\ninvestigations of lubrication under nanoconfinement conditions. The simualted\nequation of state and diffusion coefficients are in good agreement with\nexperimental data and with all-atom force fields. We use these model to analyze\nthe nano nanostructuring of ILs characteristic of cations with longer aliphatic\nchains as well as the ILs liquidvapour interfacial structure. The CG nature of\nthese models enables the simulation of very long time scales, which are needed\nto computer reliable results of dynamic and interfacial properties. For\n[C>4MIM] [BF4] the break in symmetry associated to the liquid-vapor interface\ninduces nanostructuring in polar and non-polar domains in the direction\nperpendicular to the interface plane, hence mimicking the behavior observed in\nthe bulk phases."
    },
    {
        "anchor": "Phase diagram of a two-dimensional system which stabilizes Kagome\n  lattice: Phase diagram of a two-dimensional system with a potential which stabilizes\nKagome lattice is calculated. It is shown that this system demonstrate a set of\ncrystalline and the regions of stability of these phases are calculated. The\nscenarios of melting of triangular and square crystals of the system are\ndetermined.",
        "positive": "Controlling the composition of a confined fluid by an electric field: Starting from a generic model of a pore/bulk mixture equilibrium, we propose\na novel method for modulating the composition of the confined fluid without\nhaving to modify the bulk state. To achieve this, two basic mechanisms -\nsensitivity of the pore filling to the bulk thermodynamic state and electric\nfield effect - are combined. We show by Monte Carlo simulation that the\ncomposition can be controlled both in a continuous and in a jumpwise way. Near\nthe bulk demixing instability, we demonstrate a field induced population\ninversion in the pore. The conditions for the realization of this method should\nbe best met with colloids, but being based on robust and generic mechanisms, it\nshould also be applicable to some molecular fluids."
    },
    {
        "anchor": "Defect absorption and emission for $p$-atic liquid crystals on cones: We investigate the ground state configurations of $p$-atic liquid crystals on\nfixed curved surfaces. We focus on the intrinsic geometry and show that\nisothermal coordinates are particularly convenient as they explicitly encode a\ngeometric contribution to the elastic potential. In the special case of a cone\nwith half-angle $\\beta$, the apex develops an effective topological charge of\n$-\\chi$, where $2\\pi\\chi = 2\\pi(1-\\sin\\beta)$ is the deficit angle of the cone,\nand a topological defect of charge $\\sigma$ behaves as if it had an effective\ntopological charge $Q_\\mathrm{eff} = (\\sigma - \\sigma^2/2)$ when interacting\nwith the apex. The effective charge of the apex leads to defect absorption and\nemission at the cone apex as the deficit angle of the cone is varied.\n  For total topological defect charge 1, e.g. imposed by tangential boundary\nconditions at the edge, we find that for a disk the ground state configuration\nconsists of $p$ defects each of charge $+1/p$ lying equally spaced on a\nconcentric ring of radius $d = (\\frac{p-1}{3p-1})^{\\frac{1}{2p}} R$, where $R$\nis the radius of the disk. In the case of a cone with tangential boundary\nconditions at the base, we find three types of ground state configurations as a\nfunction of cone angle: (1) for sharp cones, all of the $+1/p$ defects are\nabsorbed by the apex; (2) at intermediate cone angles, some of the $+1/p$\ndefects are absorbed by the apex and the rest lie equally spaced along a\nconcentric ring on the flank; and (3) for nearly flat cones, all of the $+1/p$\ndefects lie equally spaced along a concentric ring on the flank. Here the\ndefect positions and the absorption transitions depend intricately on $p$ and\nthe deficit angle which we analytically compute. We check these results with\nnumerical simulations for a set of commensurate cone angles and find excellent\nagreement.",
        "positive": "Stretching of viscoelastic drops by steady sliding: The sliding of non-Newtonian drops down planar surfaces results in a complex,\nentangled balance between interfacial forces and non linear viscous\ndissipation, which has been scarcely inspected. In particular, a detailed\nunderstanding of the role played by the polymer flexibility and the resulting\nelasticity of the polymer solution is still lacking. To this aim, we have\nconsidered polyacrylamide (PAA) solutions of different molecular weights,\nsuspended either in water or glycerol/water mixtures. In contrast to drops with\nstiff polymers, drops with flexible polymers exhibit a remarkable elongation in\nsteady sliding. This difference is most likely attributed to different viscous\nbending as a consequence of different shear thinning. Moreover, an \"optimal\nelasticity\" of the polymer seems to be required for this drop elongation to be\nvisible. We have complemented experimental results with numerical simulations\nof a viscoelastic FENE-P drop. This has been a decisive step to unravel how a\nchange of the elastic parameters (e.g. polymer relaxation time, maximum\nextensibility) affects the dimensionless sliding velocity."
    },
    {
        "anchor": "Glasses, replicas and all that: In these lectures I will review the approach to glasses based on the replica\nformalism. Many of the physical ideas are very similar to those of older\napproaches. The replica approach has the advantage of describing in an unified\nsetting both the behaviour near the dynamic transition (mode coupling\ntransition) and near the equilibrium transition (Kauzman transition) that is\npresent in fragile glasses. The replica method may be used to solve simple mean\nfield models, providing explicit examples of systems that may be studied\nanalytically in great details and behave similarly to the experiments. Finally,\nusing the replica formalism, it is possible to do analytic explicit\ncomputations of the properties of realistic models of glasses and the results\nare in reasonable agreement with numerical simulations.",
        "positive": "Stripe formation in bacterial systems with density-suppressed motility: Engineered bacteria in which motility is reduced by local cell density\ngenerate periodic stripes of high and low density when spotted on agar plates.\nWe study theoretically the origin and mechanism of this process in a kinetic\nmodel that includes growth and density-suppressed motility of the cells. The\nspreading of a region of immotile cells into an initially cell-free region is\nanalyzed. From the calculated front profile we provide an analytic ansatz to\ndetermine the phase boundary between the stripe and the no-stripe phases. The\ninfluence of various parameters on the phase boundary is discussed."
    },
    {
        "anchor": "Shear band dynamics from a mesoscopic modeling of plasticity: The ubiquitous appearance of regions of localized deformation (shear bands)\nin different kinds of disordered materials under shear is studied in the\ncontext of a mesoscopic model of plasticity. The model may or may not include\nrelaxational (aging) effects. In the absence of relaxational effects the model\ndisplays a monotonously increasing dependence of stress on strain-rate, and\nstationary shear bands do not occur. However, in start up experiments transient\n(although long lived) shear bands occur, that widen without bound in time. I\ninvestigate this transient effect in detail, reproducing and explaining a t^1/2\nlaw for the thickness increase of the shear band that has been obtained in\natomistic numerical simulations. Relaxation produces a negative sloped region\nin the stress vs. strain-rate curve that stabilizes the formation of shear\nbands of a well defined width, which is a function of strain-rate. Simulations\nat very low strain-rates reveal a non-trivial stick-slip dynamics of very thin\nshear bands that has relevance in the study of seismic phenomena. In addition,\nother non-stationary processes, such as stop-and-go, or strain-rate inversion\nsituations display a phenomenology that matches very well the results of recent\nexperimental studies.",
        "positive": "Comment on \"Faceting and Flattening of Emulsion Droplets: A Mechanical\n  Model\": Garc\\'ia-Aguilar et al. [Phys. Rev. Lett 126, 038001 (2021)] have shown that\nthe deformations of \"shape-shifting droplets\" are consistent with an elastic\nmodel, that, unlike previous models, includes the intrinsic curvature of the\nfrozen surfactant layer. In this Comment, we show that the interplay between\nsurface tension and intrinsic curvature in their model is in fact\nmathematically equivalent to a physically very different phase-transition\nmechanism of the same process that we developed previously [Phys. Rev. Lett.\n118, 088001 (2017); Phys. Rev. Res. 1, 023017 (2019)]. The mathematical models\ncannot therefore distinguish between the two mechanisms, and hence it is not\npossible to claim that one mechanism underlies all observed shape-shifting\nphenomena without a much more detailed comparison of experiment and theory."
    },
    {
        "anchor": "Combinatorial entropy behaviour leads to range selective binding in\n  ligand-receptor interactions: From viruses to nanoparticles, constructs functionalized with multiple\nligands display peculiar binding properties that only arise from multivalent\neffects. Using statistical mechanical modelling, we describe here how\nmultivalency can be exploited to achieve what we dub range selectivity, that\nis, binding only to targets bearing a number of receptors within a specified\nrange. We use our model to characterise the region in parameter space where one\ncan expect range selective targeting to occur, and provide experimental support\nfor this phenomenon. Overall, range selectivity represents a potential path to\nincrease the targeting selectivity of multivalent constructs.",
        "positive": "Distinguishing deformation mechanisms in elastocapillary experiments: Soft materials are known to deform due to a variety of mechanisms, including\ncapillarity, buoyancy, and swelling. In this paper, we present experiments on\npolyvinylsiloxane gel threads partially-immersed in three liquids with\ndifferent solubility, wettability, and swellability. Our results demonstrate\nthat deformations due to capillarity, buoyancy, and swelling can be of similar\nmagnitude as such threads come to static equilibrium. To account for all three\neffects being present in a single system, we derive a model capable of\nexplaining the observed data and use it to determine the force law at the\nthree-phase contact line. The results show that the measured forces are\nconsistent with the expected Young-Dupr\\'e equation, and do not require the\ninclusion of a tangential contact line force."
    },
    {
        "anchor": "Stress localization, stiffening and yielding in a model colloidal gel: We use numerical simulations and an athermal quasi-static shear protocol to\ninvestigate the yielding of a model colloidal gel. Under increasing\ndeformation, the elastic regime is followed by a significant stiffening before\nyielding takes place. A space-resolved analysis of deformations and stresses\nunravel how the complex load curve observed is the result of stress\nlocalization and that the yielding can take place by breaking a very small\nfraction of the network connections. The stiffening corresponds to the\nstretching of the network chains, unbent and aligned along the direction of\nmaximum extension. It is characterized by a strong localization of tensile\nstresses, that triggers the breaking of a few network nodes at around 30% of\nstrain. Increasing deformation favors further breaking but also shear-induced\nbonding, eventually leading to a large-scale reorganization of the gel\nstructure at the yielding. At low enough shear rates, density and velocity\nprofiles display significant spatial inhomogeneity during yielding in agreement\nwith experimental observations.",
        "positive": "An efficient approach to approximating the pair distribution function of\n  the inhomogeneous hard-sphere fluid: We introduce an approximation for the pair distribution function of the\ninhomogeneous hard sphere fluid. Our approximation makes use of our recently\npublished averaged pair distribution function at contact which has been shown\nto accurately reproduce the averaged pair distribution function at contact for\ninhomogeneous density distributions. This approach achieves greater\ncomputational efficiency than previous approaches by enabling the use of\nexclusively fixed-kernel convolutions and thus allowing an implementation using\nfast Fourier transforms. We compare results for our pair distribution\napproximation with two previously published works and Monte-Carlo simulation,\nshowing favorable results."
    },
    {
        "anchor": "Direct Imaging of Contacts and Forces in Colloidal Gels: Colloidal dispersions are prized as model systems to understand basic\nproperties of materials, and are central to a wide range of industries from\ncosmetics to foods to agrichemicals. Among the key developments in using\ncolloids to address challenges in condensed matter is to resolve the particle\ncoordinates in 3D, allowing a level of analysis usually only possible in\ncomputer simulation. However in amorphous materials, relating mechanical\nproperties to microscopic structure remains problematic. This makes it rather\nhard to understand, for example, mechanical failure. Here we address this\nchallenge by studying the contacts and the forces between particles, as well as\ntheir positions. To do so, we use a colloidal model system (an emulsion) in\nwhich the interparticle forces and local stress can be linked to the\nmicroscopic structure. We demonstrate the potential of our method to reveal\ninsights into the failure mechanisms of soft amorphous solids by determining\nlocal stress in a colloidal gel. In particular, we identify `force chains' of\nload-bearing droplets, and local stress anisotropy, and investigate their\nconnection with locally rigid packings of the droplets.",
        "positive": "Dynamics of smectic elastomers: We study the low-frequency, long-wavelength dynamics of liquid crystal\nelastomers, crosslinked in the smectic-$A$ phase, in their smectic-$A$, biaxial\nsmectic and smectic-$C$ phases. Two different yet related formulations are\nemployed. One formulation describes the pure hydrodynamics and does not\nexplicitly involve the Frank director, which relaxes to its local equilibrium\nvalue in a non-hydrodynamic time. The other formulation explicitly treats the\ndirector and applies beyond the hydrodynamic limit. We compare the\nlow-frequency, long-wavelength dynamics of smectic-$A$ elastomers to that of\nnematics and show that the two are closely related. For the biaxial smectic and\nthe smectic-$C$ phases, we calculate sound velocities and the mode structure in\ncertain symmetry directions. For the smectic-$C$ elastomers, in addition, we\ndiscuss in some detail their possible behavior in rheology experiments."
    },
    {
        "anchor": "The crumpling transition of active tethered membranes: We perform numerical simulations of active ideal and self-avoiding tethered\nmembranes. Passive ideal membranes with bending interactions are known to\nexhibit a continuous crumpling transition between a low temperature flat phase\nand a high temperature crumpled phase. Conversely, self-avoiding membranes\nremain in an extended (flat) phase for all temperatures even in the absence of\na bending energy. We find that the introduction of active fluctuations into the\nsystem produces a phase behavior that is overall consistent with that observed\nfor passive membranes. The phases and the nature of the transition for ideal\nmembranes is unchanged and active fluctuations can be remarkably accounted for\nby a simple rescaling of the temperature. For the self-avoiding membrane, we\nfind that the extended phase is preserved even in the presence of very large\nactive fluctuations.",
        "positive": "Reversible Trapping of Colloids in Microgrooved Channels via\n  Diffusiophoresis under Steady-State Solute Gradients: The controlled transport of colloids in dead-end structures is a key\ncapability that can enable a wide range of applications, such as bio-chemical\nanalysis, drug delivery and underground oil recovery. This letter presents a\nnew trapping mechanism that allows the fast (i.e., within a few minutes) and\nreversible accumulation of sub-micron particles within dead-end micro-grooves\nby means of parallel streams with different salinity level. For the first time,\nparticle focusing in dead-end structures is achieved under steady-state\ngradients. Confocal microscopy analysis and numerical investigations show that\nthe particles are trapped at a flow recirculation region within the grooves due\nto a combination of diffusiophoresis transport and hydrodynamic effects.\nCounterintuitively, the particle velocity at the focusing point is not\nvanishing and, hence, the particles are continuously transported in and out of\nthe focusing point. The accumulation process is also reversible and one can\ncyclically trap and release the colloids by controlling the salt concentration\nof the streams via a flow switching valve."
    },
    {
        "anchor": "Effect of the interaction strength and anisotropy on the\n  diffusio-phoresis of spherical colloids: Gradients in temperature, concentration or electrostatic potential cannot\nexert forces on a bulk fluid; they can, however, exert forces on a fluid in a\nmicroscopic boundary layer surrounding a (nano)colloidal solute, resulting in\nso-called phoretic flow. Here we present a simulation study of phoretic flow\naround a spherical colloid held fixed in a concentration gradient. We show that\nthe resulting flow velocity depends non-monotonically on the strength of the\ncolloid-fluid interaction. The reason for this non-monotonic dependence is that\nsolute particles are effectively trapped in a shell around the colloid and\ncannot contribute to diffusio-phoresis. We also observe that the flow depends\nsensitively on the anisotropy of solute-colloid interaction.",
        "positive": "The Generation of Turbulence by Oscillating Structures in Superfluid\n  Helium at Very Low Temperatures: The paper is concerned with the interpretation of many experiments that have\nbeen reported recently on the production of quantum turbulence by oscillating\nspheres, wires and grids in both 4He and 3He-B at temperatures so low that\nthere is a negligible fraction of normal fluid. The experimental results are\ncompared with those obtained in analogous experiments with classical fluids and\nwith preliminary simulations of the quantum turbulence. Particular attention is\npaid to observed values of drag coefficients and to the very different critical\nvelocities observed in 4He and 3He. It is tentatively concluded that in the\ncase of 4He behaviour may well be similar to that observed in the classical\nanalogues, with relatively small changes when the characteristic size of the\noscillating structure is not large compared with the quantized vortex spacing,\nbut that in the case of 3He behaviour is very different and due perhaps to very\nrapid intrinsic nucleation of the quantized vortices."
    },
    {
        "anchor": "Magneto-active elastic shells with tunable buckling strength: Shell buckling is central in many biological structures and advanced\nfunctional materials, even if, traditionally, this elastic instability has been\nregarded as a catastrophic phenomenon to be avoided for engineering structures.\nEither way, predicting critical buckling conditions remains a long-standing\nchallenge. The subcritical nature of shell buckling imparts extreme sensitivity\nto material and geometric imperfections. Consequently, measured critical loads\nare inevitably lower than classic theoretical predictions. Here, we present a\nrobust mechanism to dynamically tune the buckling strength of shells,\nexploiting the coupling between mechanics and magnetism. Our experiments on\npressurized spherical shells made of a magnetorheological elastomer demonstrate\nthe tunability of their buckling pressure via magnetic actuation. We develop a\ntheoretical model for thin magnetic elastic shells, which rationalizes the\nunderlying mechanism, in excellent agreement with experiments. A dimensionless\nmagneto-elastic buckling number is recognized as the key governing parameter,\ncombining the geometrical, mechanical, and magnetic properties of the system.",
        "positive": "Heterogeneous biological membranes regulate protein partitioning via\n  fluctuating diffusivity: Cell membranes phase separate into ordered ${\\rm L_o}$ and disordered ${\\rm\nL_d}$ domains depending on their compositions. This membrane\ncompartmentalization is heterogeneous and regulates the localization of\nspecific proteins related to cell signaling and trafficking. However, it is\nunclear how the heterogeneity of the membranes affects the diffusion and\nlocalization of proteins in ${\\rm L_o}$ and ${\\rm L_d}$ domains. Here, using\nLangevin dynamics simulations coupled with the phase-field (LDPF) method, we\ninvestigate several tens of milliseconds-scale diffusion and localization of\nproteins in heterogeneous biological membrane models showing phase separation\ninto ${\\rm L_o}$ and ${\\rm L_d}$ domains. The diffusivity of proteins exhibits\ntemporal fluctuations depending on the field composition. Increases in\nmolecular concentrations and domain preference of the molecule induce\nsubdiffusive behavior due to molecular collisions by crowding and confinement\neffects, respectively. Moreover, we quantitatively demonstrate that the protein\npartitioning into the ${\\rm L_o}$ domain is determined by the difference in\nmolecular diffusivity between domains, molecular preference of domain, and\nmolecular concentration. These results pave the way for understanding how\nbiological reactions caused by molecular partitioning may be controlled in\nheterogeneous media. Moreover, the methodology proposed here is applicable not\nonly to biological membrane systems but also to the study of diffusion and\nlocalization phenomena of molecules in various heterogeneous systems."
    },
    {
        "anchor": "Contact Instability in Adhesion and Debonding of Thin Elastic Films: Based on experiments and 3-D simulations, we show that a soft elastic film\nduring adhesion and debonding from a rigid flat surface undergoes morphological\ntransitions to pillars, labyrinths and cavities, all of which have the same\nlateral pattern length scale, close to \\lambda/H ~ 3 for thick films, H > 1\nmicrometer. The linear stability analysis and experiments show a new thin film\nregime where \\lambda/H \\approx 3+ 2 (\\gamma/3 \\mu H)^(1/4) (\\gamma is surface\ntension, \\mu is shear modulus) because of significant surface energy penalty\n(for example, \\lambda/H = 6 for H = 200 nm; \\mu = 1MPa).",
        "positive": "Long-time diffusion and energy transfer in polydisperse mixtures of\n  particles with different temperatures: Evidence suggests that the transport rate of a passive particle at long\ntimescales is enhanced due to interactions with the surrounding active ones in\na size- and composition-dependent manner. Using a system of particles with\ndifferent temperatures, we probe these effects in dilute solutions and derive\nlong-time friction and self-diffusion coefficients as functions of volume\nfractions, sizes and temperatures of particles in $d=2$ and 3 dimensions. Thus,\nwe model excluded-volume interactions for nonequilibrium systems but also\nextend the scope to short-range soft potentials and compare our results to\nBrownian-dynamics simulations. Remarkably, we show that both viscosity and\nenergy flux display a nonlinear dependence on size. The simplicity of our\nformalism allows to discover various interesting scenarios that can be relevant\nfor biological systems and active colloids."
    },
    {
        "anchor": "Measurement of the pure dissolution rate constant of a mineral in water: We present here a methodology, using holographic interferometry, enabling to\nmeasure the pure surface reaction rate constant of the dissolution of a mineral\nin water, unambiguously free from the influence of mass transport. We use that\ntechnique to access to this value for gypsum and we demonstrate that it was\nnever measured before but could be deduced a posteriori from the literature\nresults if hydrodynamics is taken into account with accuracy. It is found to be\nmuch smaller than expected. This method enables to provide reliable rate\nconstants for the test of dissolution models and the interpretation of in situ\nmeasurements, and gives clues to explain the inconsistency between dissolution\nrates of calcite and aragonite, for instance, in the literature.",
        "positive": "Spherical Colloids: Effect of Discrete Macroion Charge Distribution and\n  Counterion Valence: We report the coupled effects of macroion charge discretization and\ncounterion valence in the primitive model for spherical colloids. Instead of\nconsidering a uniformly charged surface, as it is traditionally done, we\nconsider a more realistic situation where \\textit{discrete monovalent\nmicroscopic charges} are randomly distributed over the sphere. Monovalent or\nmultivalent counterions ensure global electroneutrality. We use molecular\ndynamics simulations to study these effects at the ground state and for finite\ntemperature. The ground state analysis concerns the counterion structure and\n\\textit{charge inversion}. Results are discussed in terms of simple analytical\nmodels. For finite temperature, strong and weak Coulomb couplings are treated.\nIn this situation of finite temperature, we considered and discussed the\nphenomena of ionic pairing (pinning) and unpairing (unpinning)."
    },
    {
        "anchor": "Polymer adsorption onto random planar surfaces: Interplay of polymer and\n  surface correlation: We study the adsorption of homogeneous or heterogeneous polymers onto\nheterogeneous planar surfaces with exponentially decaying site-site\ncorrelations, using a variational reference system approach. As a main result,\nwe derive simple equations for the adsorption-desorption transition line. We\nshow that the adsorption threshold is the same for systems with quenched and\nannealed disorder. The results are discussed with respect to their implications\nfor the physics of molecular recognition.",
        "positive": "Jamming of Deformable Polygons: There are two main classes of physics-based models for two-dimensional\ncellular materials: packings of repulsive disks and the vertex model. These\nmodels have several disadvantages. For example, disk interactions are typically\na function of particle overlap, yet the model assumes that the disks remain\ncircular during overlap. The shapes of the cells can vary in the vertex model,\nhowever, the packing fraction is fixed at $\\phi=1$. Here, we describe the\ndeformable particle model (DPM), where each particle is a polygon composed of a\nlarge number of vertices. The total energy includes three terms: two quadratic\nterms to penalize deviations from the preferred particle area $a_0$ and\nperimeter $p_0$ and a repulsive interaction between DPM polygons that penalizes\noverlaps. We performed simulations to study the onset of jamming in packings of\nDPM polygons as a function of asphericity, ${\\cal A} = p_0^2/4\\pi a_0$. We show\nthat the packing fraction at jamming onset $\\phi_J({\\cal A})$ grows with\nincreasing ${\\cal A}$, reaching confluence at ${\\cal A} \\approx 1.16$. ${\\cal\nA}^*$ corresponds to the value at which DPM polygons completely fill the cells\nobtained from a surface-Voronoi tessellation. Further, we show that DPM\npolygons develop invaginations for ${\\cal A} > {\\cal A}^*$ with excess\nperimeter that grows linearly with ${\\cal A}-{\\cal A}^*$. We confirm that\npackings of DPM polygons are solid-like over the full range of ${\\cal A}$ by\nshowing that the shear modulus is nonzero."
    },
    {
        "anchor": "Critical behavior of the Widom-Rowlinson mixture: coexistence diameter\n  and order parameter: The critical behavior of the Widom-Rowlinson mixture [J. Chem. Phys. 52, 1670\n(1970)] is studied in d=3 dimensions by means of grand canonical Monte Carlo\nsimulations. The finite size scaling approach of Kim, Fisher, and Luijten\n[Phys. Rev. Lett. 91, 065701 (2003)] is used to extract the order parameter and\nthe coexistence diameter. It is demonstrated that the critical behavior of the\ndiameter is dominated by a singular term proportional to t^(1-alpha), with t\nthe relative distance from the critical point, and alpha the critical exponent\nof the specific heat. No sign of a term proportional to t^(2beta) could be\ndetected, with beta the critical exponent of the order parameter, indicating\nthat pressure-mixing in this model is small. The critical density is measured\nto be rho*sigma^3 = 0.7486 +/- 0.0002, with sigma the particle diameter. The\ncritical exponents alpha and beta, as well as the correlation length exponent\nnu, are also measured and shown to comply with d=3 Ising criticality.",
        "positive": "Determination of Inter-Phase Line Tension in Langmuir Films: A Langmuir film is a molecularly thin film on the surface of a fluid; we\nstudy the evolution of a Langmuir film with two co-existing fluid phases driven\nby an inter-phase line tension and damped by the viscous drag of the underlying\nsubfluid. Experimentally, we study an 8CB Langmuir film via digitally-imaged\nBrewster Angle Microscopy (BAM) in a four-roll mill setup which applies a\ntransient strain and images the response. When a compact domain is stretched by\nthe imposed strain, it first assumes a bola shape with two tear-drop shaped\nreservoirs connected by a thin tether which then slowly relaxes to a circular\ndomain which minimizes the interfacial energy of the system. We process the\ndigital images of the experiment to extract the domain shapes. We then use one\nof these shapes as an initial condition for the numerical solution of a\nboundary-integral model of the underlying hydrodynamics and compare the\nsubsequent images of the experiment to the numerical simulation. The numerical\nevolutions first verify that our hydrodynamical model can reproduce the\nobserved dynamics. They also allow us to deduce the magnitude of the line\ntension in the system, often to within 1%. We find line tensions in the range\nof 200-600 pN; we hypothesize that this variation is due to differences in the\nlayer depths of the 8CB fluid phases."
    },
    {
        "anchor": "Interfacial tension of the isotropic--nematic interface in suspensions\n  of soft spherocylinders: The isotropic to nematic transition in a system of soft spherocylinders is\nstudied by means of grand canonical Monte Carlo simulations. The probability\ndistribution of the particle density is used to determine the coexistence\ndensity of the isotropic and the nematic phases. The distributions are also\nused to compute the interfacial tension of the isotropic--nematic interface,\nincluding an analysis of finite size effects. Our results confirm that the\nOnsager limit is not recovered until for very large elongation, exceeding at\nleast L/D=40, with L the spherocylinder length and D the diameter. For smaller\nelongation, we find that the interfacial tension increases with increasing L/D,\nin agreement with theoretical predictions.",
        "positive": "Three dimensional hydrodynamic lattice-gas simulations of domain growth\n  and self-assembly in binary immiscible and ternary amphiphilic fluids: We simulate the dynamics of phase assembly in binary immiscible fluids and\nternary microemulsions using a three-dimensional hydrodynamic lattice gas\napproach. For critical spinodal decomposition we perform the scaling analysis\nin reduced variables introduced by Jury et al. and Kendon et al. We find a\nlate-stage scaling exponent consistent with the inertial regime. However, as\nobserved with the previous lattice-gas model of Appert et al. our data does not\nfall in the same range of reduced length and time as that of Kendon et al. For\noff-critical binary spinodal decomposition we observe a reduction of the\neffective exponent with the volume fraction of the minority phase. However, the\nn=1/3 Lifshitz-Slyzov-Wagner droplet coalescence exponent is not observed.\nAdding a sufficient number of surfactant particles to a critical quench of\nbinary immiscible fluids produces a ternary bicontinuous microemulsion. We\nobserve a change in scaling behaviour from algebraic to logarithmic growth for\namphiphilic fluids in which the domain growth is not arrested. For formation of\na microemulsion where the domain growth is halted we find a stretched\nexponential growth law provides the best fit to the data."
    },
    {
        "anchor": "Spatial flocking: Control by speed, distance, noise and delay: Fish, birds, insects and robots frequently swim or fly in groups. During\ntheir 3 dimensional collective motion, these agents do not stop, they avoid\ncollisions by strong short-range repulsion, and achieve group cohesion by weak\nlong-range attraction. In a minimal model that is isotropic, and continuous in\nboth space and time, we demonstrate that (i) adjusting speed to a preferred\nvalue, combined with (ii) radial repulsion and an (iii) effective long-range\nattraction are sufficient for the stable ordering of autonomously moving agents\nin space. Our results imply that beyond these three rules ordering in space\nrequires no further rules, for example, explicit velocity alignment, anisotropy\nof the interactions or the frequent reversal of the direction of motion,\nfriction, elastic interactions, sticky surfaces, a viscous medium, or vertical\nseparation that prefers interactions within horizontal layers. Noise and delays\nare inherent to the communication and decisions of all moving agents. Thus,\nnext we investigate their effects on ordering in the model. First, we find that\nthe amount of noise necessary for preventing the ordering of agents is not\nsufficient for destroying order. In other words, for realistic noise amplitudes\nthe transition between order and disorder is rapid. Second, we demonstrate that\nordering is more sensitive to displacements caused by delayed interactions than\nto uncorrelated noise (random errors). Third, we find that with changing\ninteraction delays the ordered state disappears at roughly the same rate,\nwhereas it emerges with different rates. In summary, we find that the model\ndiscussed here is simple enough to allow a fair understanding of the modeled\nphenomena, yet sufficiently detailed for the description and management of\nlarge flocks with noisy and delayed interactions. Our code is available at\nhttp://github.com/fij/floc",
        "positive": "Active Contact Forces Drive Non-Equilibrium Fluctuations in Membrane\n  Vesicles: We analyze the non-equilibrium shape fluctuations of giant unilamellar\nvesicles encapsulating motile bacteria. Owing to bacteria--membrane collisions,\nwe experimentally observe a significant increase in the magnitude of membrane\nfluctuations at low wave numbers, compared to the well-known thermal\nfluctuation spectrum. We interrogate these results by numerically simulating\nmembrane height fluctuations via a modified Langevin equation, which includes\nbacteria--membrane contact forces. Taking advantage of the length and time\nscale separation of these contact forces and thermal noise, we further\ncorroborate our results with an approximate theoretical solution to the\ndynamical membrane equations. Our theory and simulations demonstrate excellent\nagreement with non-equilibrium fluctuations observed in experiments. Moreover,\nour theory reveals that the fluctuation--dissipation theorem is not broken by\nthe bacteria; rather, membrane fluctuations can be decomposed into thermal and\nactive components."
    },
    {
        "anchor": "Adding Salt to an Aqueous Solution of t-Butanol: Is Hydrophobic\n  Association Enhanced or Reduced?: Recent neutron scattering experiments on aqueous salt solutions of\namphiphilic t-butanol by Bowron and Finney [Phys. Rev. Lett. {\\bf 89}, 215508\n(2002); J. Chem. Phys. {\\bf 118}, 8357 (2003)] suggest the formation of\nt-butanol pairs, bridged by a chloride ion via ${O}-{H}...{Cl}^-$\nhydrogen-bonds, and leading to a reduced number of intermolecular hydrophobic\nbutanol-butanol contacts. Here we present a joint experimental/theoretical\nstudy on the same system, using a combination of molecular dynamics simulations\nand nuclear magnetic relaxation measurements. Both theory and experiment\nclearly support the more intuitive scenario of an enhanced number of\nhydrophobic contacts in the presence of the salt, as it would be expected for\npurely hydrophobic solutes [J. Phys. Chem. B {\\bf 107}, 612 (2003)]. Although\nour conclusions arrive at a structurally completely distinct scenario, the\nmolecular dynamics simulation results are within the experimental errorbars of\nthe Bowron and Finney work.",
        "positive": "Freezing and Melting Hysteresis Measurements in Solutions of Hyperactive\n  Antifreeze Protein from an Antarctic Bacteria: Antifreeze proteins (AFPs) evolved in cold-adapted organisms and serve to\nprotect them against freezing in cold conditions by arresting ice crystal\ngrowth. Recently, we have shown quantitatively that adsorption of AFPs not only\nprevents ice from growing but also from melting. This melting inhibition by\nAFPs, which results in superheated ice (Celik et al, PNAS 2010), is not a\nwell-known phenomenon. Here we present our recent findings in which the Ca2+ -\ndependent hyperactive AFP from Marinomonas primoryensis (MpAFP) clearly\ndisplays this property. Additionally, we found that an ice crystal that is\ninitially stabilized and protected by this type of AFP can be overgrown and\nthen melted back to the original crystal. This repeatable process is likely due\nto melting inhibition, and supports the idea that AFPs bind irreversibly to ice\nsurfaces."
    },
    {
        "anchor": "Local elastic response measured near the colloidal glass transition: We examine the response of a dense colloidal suspension to a local force\napplied by a small magnetic bead. For small forces, we find a linear\nrelationship between the force and the displacement, suggesting the medium is\nelastic, even though our colloidal samples macroscopically behave as fluids. We\ninterpret this as a measure of the strength of colloidal caging, reflecting the\nproximity of the samples' volume fractions to the colloidal glass transition.\nThe strain field of the colloidal particles surrounding the magnetic probe\nappears similar to that of an isotropic homogeneous elastic medium. When the\napplied force is removed, the strain relaxes as a stretched exponential in\ntime. We introduce a model that suggests this behavior is due to the diffusive\nrelaxation of strain in the colloidal sample.",
        "positive": "Magnetomechanical response of bilayered magnetic elastomers: Magnetic elastomers are appealing materials from an application point of\nview: they combine the mechanical softness and deformability of polymeric\nsubstances with the addressability by external magnetic fields. In this way,\nmechanical deformations can be reversibly induced and elastic moduli can be\nreversibly adjusted from outside. So far, mainly the behavior of\nsingle-component magnetic elastomers and ferrogels has been studied. Here, we\ngo one step further and analyze the magnetoelastic response of a bilayered\nmaterial composed of two different magnetic elastomers. It turns out that,\nunder appropriate conditions, the bilayered magnetic elastomer can show a\nstrongly amplified deformational response in comparison to a single-component\nmaterial. Furthermore, a qualitatively opposite response can be obtained, i.e.\\\na contraction along the magnetic field direction (as opposed to an elongation\nin the single-component case). We hope that our results will further stimulate\nexperimental and theoretical investigations directly on bilayered magnetic\nelastomers, or, in a further hierarchical step, on bilayered units embedded in\nyet another polymeric matrix."
    },
    {
        "anchor": "Microparticle assembly pathways on lipid membranes: Understanding interactions between microparticles and lipid membranes is of\nincreasing importance, especially for unraveling the influence of microplastics\non our health and environment. Here, we study how a short-ranged adhesive force\nbetween microparticles and model lipid membranes causes membrane-mediated\nparticle assembly. Using confocal microscopy, we observe the initial particle\nattachment to the membrane, then particle wrapping, and in rare cases\nspontaneous membrane tubulation. In the attached state, we measure that the\nparticle mobility decreases by 26%. If multiple particles adhere to the same\nvesicle, their initial single-particle state determines their interactions and\nsubsequent assembly pathways: 1) attached particles only aggregate when small\nadhesive vesicles are present in solution, 2) wrapped particles reversibly\nattract one another by membrane deformation, and 3) a combination of wrapped\nand attached particles form membrane-mediated dimers, which further assemble\ninto a variety of complex structures. The experimental observation of distinct\nassembly pathways induced only by a short ranged membrane-particle adhesion,\nshows that a cellular cytoskeleton or other active components are not required\nfor microparticle aggregation. We suggest that this membrane-mediated\nmicroparticle aggregation is a reason behind reported long retention times of\npolymer microparticles in organisms.",
        "positive": "Theoretical and numerical investigations on shapes of planar lipid\n  monolayer domains: Shapes of planar lipid monolayer domains at the air-water interface are\ntheoretically and numerically investigated by minimizing the formation energy\nof the domains which consist of the surface energy, line tension energy, and\ndipole electrostatic energy. The shape equation which describes boundary curves\nof the domains at equilibrium state is derived from the first order variation\nof the formation energy. A relaxation method is proposed to find the numerical\nsolutions of the shape equation. The theoretical and numerical results are in\ngood agreement with previous experimental observation. Some new shapes not\nobserved in previous experiments are also obtained, which awaits experimental\nconfirmation in the future."
    },
    {
        "anchor": "Relaxation dynamics of two interacting electrical double-layers in a 1D\n  Coulomb system: We consider an out-of-equilibrium one-dimensional model for two electrical\ndouble-layers. With a combination of exact calculations and Brownian Dynamics\nsimulations, we compute the relaxation time ($\\tau$) for an electroneutral\nsalt-free suspension, made up of two fixed colloids, with $N$ neutralizing\nmobile counterions. For $N$ odd, the two double-layers never decouple,\nirrespective of their separation $L$; this is the regime of like-charge\nattraction, where $\\tau$ exhibits a diffusive scaling in $L^2$ for large $L$.\nOn the other hand, for even $N$, $L$ no longer is the relevant length scale for\nsetting the relaxation time; this role is played by the Bjerrum length. This\nleads to distinctly different dynamics: for $N$ even, thermal effects are\ndetrimental to relaxation, increasing $\\tau$, while they accelerate relaxation\nfor $N$ odd. Finally, we also show that the mean-field theory is recovered for\nlarge $N$ and moreover, that it remains an operational treatment down to\nrelatively small values of $N$ ($N>3$).",
        "positive": "Light-controllable hybrid aligning layer based on LIPSS on sapphire\n  surface and PVCN-F film: The creation of aligning layers for the uniform orientation of liquid\ncrystals is significant for both research and the application of liquid\ncrystals. For all applications, the creation of aligning layers possessing\ncontrollable characteristics such as azimuthal and polar anchoring energies,\neasy-axis of director alignment and pre-tilt angle, in the same way as it is\nachieved by using photoaligning layers processed by light, is very important.\nHere, aligning properties of hybrid aligning layers created on the basis of\nsapphire surfaces additionally coated by photoaligning layer of PVCN-F are\nstudied. These hybrid layers possess the properties of the nano-structured\nsapphire layer and the photosensitive PVCN-F layer, and complement each other.\nThe irradiation time dependence of the azimuthal anchoring energy of the hybrid\nlayers is studied. By using certain experimental conditions during irradiation\nof hybrid layers, e.g., polarisation of light and irradiation time, a minimum\nvalue of the azimuthal anchoring energy, close to zero, was obtained. Atomic\nforce microscope studies of the irradiated hybrid layers were also carried out.\nIt was found that the behavior of the contact angle of nematic droplets placed\non treated sapphire surfaces are in good agreement with properties of hybrid\naligning layers and parameters of structuring surface obtained from AFM images."
    },
    {
        "anchor": "Comparative study of multiscale computational strategies for materials\n  with discrete microstructures: The evolution of local defects such as dislocations and cracks often\ndetermines the performance of engineering materials. For a proper description\nand understanding of these phenomena, one needs to descend to a very small\nscale, at which the discreteness of the material emerges. Fully-resolved\ndiscrete numerical models often suffer from excessive computing expenses when\nused for application-scale considerations. More efficient multiscale simulation\nprocedures are thus called for, capable of capturing the most significant\nmicroscopic phenomena while being computationally tractable. Two broad classes\nof methods are available in the literature. The first class considers the\nfully-resolved discrete system, which is subsequently reduced through suitable\nmathematical tools such as projection and reduced integration. The second class\nfirst homogenizes the discrete system into an equivalent continuum formulation,\ninto which the main phenomena are added through specific enrichments. This\npaper provides a thorough comparison of the two different modeling philosophies\nin terms of their theory, accuracy, and performance. To this goal, two typical\nrepresentatives are adopted: the Quasicontinuum method for the first class, and\nan effective continuum with an embedded cohesive zone model for the second\nclass. Two examples are employed to demonstrate capabilities and limitations of\nboth approaches: dislocation propagation and pile-up against a coherent phase\nboundary, and a three-point bending test of a concrete specimen with crack\npropagation. In both cases, the accuracy of the two methods is compared against\nthe fully-resolved discrete reference model. It is shown that whereas continuum\nmodels with embedded cohesive zones offer good performance to accuracy ratios,\nthey might fail to capture unexpected mechanical behavior. The Quasicontinuum\nmethod offers more flexibility at a higher computational cost.",
        "positive": "Are Temperature and other Thermodynamics Variables efficient Concepts\n  for describing Granular Gases and/or Flows ?: Granular flows and vibro-fluidised granular gases have been extensively\nstudied recently; most of the theoretical analyses and the experimental\ndescriptions use temperature and other thermodynamics concepts. However, taking\nthe very simple case of a vibro-fluidised gas made of identical particles, we\nshow the lack of efficiency of such concepts for the understanding of the\nphysics of such systems. This results from both (i) the fact that the vibrator\ndoes not transmit the same amount of energy to each particle, but an amount\nwhich depends on its mass and/or its size and (ii) from the fact that it is a\nstrongly dissipative medium. We conclude that most experimental device works\nrather as velostat as a thermostat. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn"
    },
    {
        "anchor": "Attractive Interactions Between Rod-like Polyelectrolytes: Polarization,\n  Crystallization, and Packing: We study the attractive interactions between rod-like charged polymers in\nsolution that appear in the presence of multi-valence counterions. The\ncounterions condensed to the rods exhibit both a strong transversal\npolarization and a longitudinal crystalline arrangement. At short distances\nbetween the rods, the fraction of condensed counterions increases, and the\nmajority of these occupy the region between the rods, where they minimize their\nrepulsive interactions by arranging themselves into packing structures. The\nattractive interaction is strongest for multivalent counterions. Our model\ntakes into account the hard-core volume of the condensed counterions and their\nangular distribution around the rods. The hard core constraint strongly\nsuppresses longitudinal charge fluctuations.",
        "positive": "A state variable for crumpled thin sheets: Despite the apparent ease with which a sheet of paper is crumpled and tossed\naway, crumpling dynamics are often considered a paradigm of complexity. This\ncomplexity arises from the infinite number of configurations a disordered\ncrumpled sheet can take. Here we experimentally show that key aspects of\ncrumpling have a very simple description; the evolution of the damage in\ncrumpling dynamics can largely be described by a single global quantity, the\ntotal length of all creases. We follow the evolution of the damage network in\nrepetitively crumpled elastoplastic sheets, and show that the dynamics of this\nquantity are deterministic, and depend only on the instantaneous state of the\ncrease network and not at all on the crumpling history. We also show that this\nglobal quantity captures the crumpling dynamics of a sheet crumpled for the\nfirst time. This leads to a remarkable reduction in complexity, allowing a\ndescription of a highly disordered system by a single state parameter. Similar\nstrategies may also be useful in analyzing other systems that evolve under\ngeometric and mechanical constraints, from faulting of tectonic plates to the\nevolution of proteins."
    },
    {
        "anchor": "Mixtures of blue phase liquid crystal with simple liquids: elastic\n  emulsions and cubic fluid cylinders: We investigate numerically the behaviour of a phase-separating mixture of a\nblue phase I liquid crystal with an isotropic fluid. The resulting morphology\nis primarily controlled by an inverse capillary number, $\\chi$, setting the\nbalance between interfacial and elastic forces. When $\\chi$ and the\nconcentration of the isotropic component are both low, the blue phase\ndisclination lattice templates a cubic array of fluid cylinders. For larger\n$\\chi$, the isotropic phase arranges primarily into liquid emulsion droplets\nwhich coarsen very slowly, rewiring the blue phase disclination lines into an\namorphous elastic network. Our blue phase/simple fluid composites can be\nexternally manipulated: an electric field can trigger a morphological\ntransition between cubic fluid cylinder phases with different topologies.",
        "positive": "Structure and phase behavior of colloidal dumbbells with tunable\n  attractive interactions: We investigate thermodynamic and structural properties of colloidal dumbbells\nin the framework provided by the Reference Interaction Site Model (RISM) theory\nof molecular fluids and Monte Carlo simulations. We consider two different\nmodels: in the first one we set identical square-well attractions on the two\ntangent spheres composing the molecule (SW-SW model); in the second scheme, one\nof square-well interactions is switched off (HS-SW model). Appreciable\ndifferences emerge between the physical properties of the two models.\nSpecifically, the $k \\to 0$ behavior of SW-SW structure factors $S(k)$ points\nto the presence of a gas-liquid coexistence, as confirmed by subsequent fluid\nphase equilibria calculations. Conversely, the HS-SW $S(k)$ develops a low-$k$\npeak, signaling the presence of aggregates; such a process destabilizes the\ngas-liquid phase separation, promoting at low temperatures the formation of a\ncluster phase, whose structure depends on the system density. We further\ninvestigate such differences by studying the phase behavior of a series of\nintermediate models, obtained from the original SW-SW by progressively reducing\nthe depth of one square-well interaction. RISM structural predictions\npositively reproduce the simulation data, including the rise of $S(k \\to 0$) in\nthe SW-SW model and the low-$k$ peak in the HS-SW structure factor. As for the\nphase behavior, RISM agrees with Monte Carlo simulations in predicting a\ngas-liquid coexistence for the SW-SW model (though the critical parameters\nappears overestimated by the theory) and its progressive disappearance moving\ntoward the HS-SW model."
    },
    {
        "anchor": "How a Supercooled Liquid Borrows Structure from the Crystal: Using computer simulations, we establish that the structure of a supercooled\nbinary atomic liquid mixture consists of common neighbour structures similar to\nthose found in the equilibrium crystal phase, a Laves structure. Despite the\nlarge accumulation of crystal-like structure, we establish that the supercooled\nliquid represents a true metastable liquid and that liquid can borrow crystal\nstructure without being destabilized. We consider whether this feature might be\nthe origin of all instances of liquids of a strongly favoured local structure.",
        "positive": "Droplets on Lubricated Surfaces: The slow dynamics of skirt formation: A key question in the interaction of droplets with lubricated and\nliquid-infused surfaces is what determines the apparent contact angle of\ndroplets. Previous work has determined this using measured values of the\ngeometry of the `skirt' -- the meniscus-like deformation that forms around the\nbase of the deposited droplet. Here, we consider theoretically the equilibrium\nof a droplet on a smooth, impermeable lubricant-coated surface, and argue that\nthe small effect of gravity within the skirt and the size of the substrate are\nimportant for determining the final equilibrium. However, we also show that the\nevolution of the skirt towards this ultimate equilibrium is extremely slow (on\nthe order of days for typical experimental parameter values). We therefore\nsuggest that previous experiments on smooth lubricated surfaces may have\nobserved only slowly-evolving transients, rather than `true' equilibria,\npotentially explaining why a wide range of skirt sizes have been reported."
    },
    {
        "anchor": "Phase behavior of symmetric linear multiblock copolymers: Molecular dynamics simulations are used to study the phase behavior of a\nsingle linear multiblock copolymer with blocks of A- and B-type monomers under\npoor solvent conditions, varying the block length $N$, number of blocks $n$,\nand the solvent quality (by variation of the temperature $T$). The fraction $f$\nof A-type monomers is kept constant and equal to 0.5, and always the lengths of\nA and B blocks were equal ($N_{A}=N_{B}=N$), as well as the number of blocks\n($n_{A}=n_{B}=n$). We identify the three following regimes where: (i) full\nmicrophase separation between blocks of different type occurs (all blocks of\nA-type monomers form a single cluster, while all blocks of B-type monomers form\nanother), (ii) full microphase separation is observed with a certain\nprobability, and (iii) full microphase separation can not take place. For very\nhigh number of blocks $n$ and very high $N$ (not accessible to our simulations)\nfurther investigation is needed.",
        "positive": "Lattice-Boltzmann Hydrodynamics of Anisotropic Active Matter: A plethora of active matter models exist that describe the behavior of\nself-propelled particles (or swimmers), both with and without hydrodynamics.\nHowever, there are few studies that consider shape-anisotropic swimmers and\ninclude hydrodynamic interactions. Here, we introduce a simple method to\nsimulate self-propelled colloids interacting hydrodynamically in a viscous\nmedium using the lattice-Boltzmann technique. Our model is based on\nraspberry-type viscous coupling and a force/counter-force formalism which\nensures that the system is force free. We consider several anisotropic shapes\nand characterize their hydrodynamic multipolar flow field. We demonstrate that\nshape-anisotropy can lead to the presence of a strong quadrupole and octupole\nmoments, in addition to the principle dipole moment. The ability to simulate\nand characterize these higher-order moments will prove crucial for\nunderstanding the behavior of model swimmers in confining geometries."
    },
    {
        "anchor": "Polarizable ions at interfaces: A non-perturbative theory is presented which allows to calculate the\nsolvation free energy of polarizable ions near a water-vapor and water-oil\ninterfaces. The theory predicts that larger halogen anions are adsorbed at the\ninterface, while the alkali metal cations are repelled from it. The density\nprofiles calculated theoretically are similar to those obtained using the\nmolecular dynamics simulations with polarizable force fields.",
        "positive": "Self-Consistent Field Theory of Disordered Block-Copolymers: We derive the mean-field theory of disordered block-copolymers composed of\ntwo monomeric species, combining Edwards' functional method with the replica\ntechnique of disordered systems. In the absence of disorder we recover the\ncanonical self-consistent field theory of inhomogeneous polymers. In the\npresence of sequence disorder the theory can be regarded as a comprehensive,\nnovel self-consistent treatment of copolymer melts, unifying the weak- and\nstrong-inhomogeneous regimes. In particular, we study the stability of the\nmicrophase separation transition in a melt of diblock-copolymers, composed of\n$N$ monomers and equal $A$- $B$-volume fraction, against the disruptive effect\nof disorder. We obtain a phase diagram in terms of the relevant parameters,\nnamely the rescaled Flory-Huggins parameter $\\chi N$ and disorder strength $p$."
    },
    {
        "anchor": "Dynamics of matter solitons in weakly modulated optical lattices: It is shown that matter solitons can be effectively managed by means of\nsmooth variations of parameters of optical lattices in which the condensate is\nloaded. The phenomenon is based on the effect of lattice modulations on the\ncarrier wave transporting the soliton and that is why is well understood in\nterms of the effective mass approach, where a particular spatial configuration\nof the band structure is of primary importance. Linear, parabolic, and\nspatially localized modulations are considered as the case examples. It is\nshown that these defects can originate accelerating and oscillating motion of\nmatter solitons as well as simulate soliton interaction with attractive and\nrepulsive defects.",
        "positive": "Theory of Light Emission in Sonoluminescence as Thermal Radiation: Based on the model proposed by Hilgenfeldt {\\it at al.} [Nature {\\bf 398},\n401 (1999)], we present here a comprehensive theory of thermal radiation in\nsingle-bubble sonoluminescence (SBSL). We first invoke the generalized\nKirchhoff's law to obtain the thermal emissivity from the absorption\ncross-section of a multilayered sphere (MLS). A sonoluminescing bubble, whose\ninternal structure is determined from hydrodynamic simulations, is then\nmodelled as a MLS and in turn the thermal radiation is evaluated. Numerical\nresults obtained from simulations for argon bubbles show that our theory\nsuccessfully captures the major features observed in SBSL experiments."
    },
    {
        "anchor": "Dynamics of Self-Assembly of Model Viral Capsids in the Presence of a\n  Fluctuating Membrane: A coarse-grained computational model is used to investigate the effect of a\nfluctuating fluid membrane on the dynamics of patchy-particle assembly into\nvirus capsid-like cores. Results from simulations for a broad range of\nparameters are presented, showing the effect of varying interaction strength,\nmembrane stiffness and membrane viscosity. Furthermore, the effect of\nhydrodynamic interactions is investigated. Attraction to a membrane may promote\nassembly, including for sub-unit interaction strengths for which it does not\noccur in the bulk, and may also decrease single-core assembly time. The\nmembrane budding rate is strongly increased by hydrodynamic interactions. The\nmembrane deformation rate is important in determining the finite-time yield.\nHigher rates may decrease the entropic penalty for assembly and help guide\nsub-units towards each other but may also block partial cores from being\ncompleted. For increasing sub-unit interaction strength, three regimes with\ndifferent effects of the membrane are identified.",
        "positive": "Geometric Mechanics of Curved Crease Origami: Folding a sheet of paper along a curve can lead to structures seen in\ndecorative art and utilitarian packing boxes. Here we present a theory for the\nsimplest such structure: an annular circular strip that is folded along a\ncentral circular curve to form a three-dimensional buckled structure driven by\ngeometrical frustration. We quantify this shape in terms of the radius of the\ncircle, the dihedral angle of the fold and the mechanical properties of the\nsheet of paper and the fold itself. When the sheet is isometrically deformed\neverywhere except along the fold itself, stiff folds result in creases with\nconstant curvature and oscillatory torsion. However, relatively softer folds\ninherit the broken symmetry of the buckled shape with oscillatory curvature and\ntorsion. Our asymptotic analysis of the isometrically deformed state is\ncorroborated by numerical simulations which allow us to generalize our analysis\nto study multiply folded structures."
    },
    {
        "anchor": "Surface energy of strained amorphous solids: Surface stress and surface energy are fundamental quantities which\ncharacterize the interface between two materials. Although these quantities are\nidentical for interfaces involving only fluids, the Shuttleworth effect\ndemonstrates that this is not the case for most interfaces involving solids,\nsince their surface energies change with strain. Crystalline materials are\nknown to have strain dependent surface energies, but in amorphous materials,\nsuch as polymeric glasses and elastomers, the strain dependence is debated due\nto a dearth of direct measurements. Here, we utilize contact angle measurements\non strained glassy and elastomeric solids to address this matter. We show\nconclusively that interfaces involving polymeric glasses exhibit strain\ndependent surface energies, and give strong evidence for the absence of such a\ndependence for incompressible elastomers. The results provide fundamental\ninsight into our understanding of the interfaces of amorphous solids and their\ninteraction with contacting liquids.",
        "positive": "Non-analytic curvature contributions to solvation free energies:\n  influence of drying: We investigate the solvation of a hard spherical cavity, of radius $R$,\nimmersed in a fluid for which the interparticle forces are short ranged. For\nthermodynamic states lying close to the liquid binodal, where the chemical\npotential deviation $\\delta \\mu\\equiv \\mu - \\mu_{co}(T)$ is very small and\npositive, complete wetting by gas (drying) occurs and two regimes of\ninterfacial behavior can be identified. These are characterized by the length\nscale $R_c=2 \\gamma_{gl}^\\infty/(\\Delta \\rho \\delta \\mu)$, where\n$\\gamma_{gl}^\\infty$ is the planar gas-liquid surface tension and $\\Delta \\rho$\nis the difference in coexisting densities at temperature $T$. For $R>R_c$, the\ninterfacial free energy and the density profile of the fluid near the hard wall\ncan be expanded in powers of the curvature $R^{-1}$, in keeping with the\nanalysis of Stillinger and Cotter, J. Chem. Phys. {\\bf 55}, 3449 (1971). In the\nother regime, $R<R_c$, the interfacial free energy and its derivatives acquire\nterms depending on $\\ln R$. Since $R_c^{-1}$ can be made arbitrarily small this\nimplies non-analytic behavior, as $R^{-1}\\to 0$, of the work of formation of a\nhard spherical cavity and of the Gibbs adsorption and the fluid density at\ncontact with the wall. Our analysis, which is based on an effective interfacial\nHamiltonian combined with exact statistical mechanical sum rules, is confirmed\nfully by the results of microscopic density functional calculations for a\nsquare-well fluid."
    },
    {
        "anchor": "Magnetic Tilting in Nematic Liquid Crystals driven by Self-Assembly: Self-assembly is one of the crucial mechanisms allowing to design\nmultifunctional materials. Soft hybrid materials contain components of\ndifferent nature and exhibit competitive interactions which drive\nself-organisation into structures of a particular function. Here we demonstrate\na novel type of a magnetic hybrid material where the molecular tilt can be\nmanipulated through a delicate balance between the topologically-assisted\ncolloidal self-assembly of \\rev{magnetic nanoparticles} and the anisotropic\nmolecular interactions in a liquid crystal matrix.",
        "positive": "Mixed scenario of the charged liquid surface reconstruction: Discussed in the paper is a mixed scenario of the charged liquid surface\nreconstruction in the situation where the 2D surface charge density is close to\nits saturation value."
    },
    {
        "anchor": "Effects of grain shape on packing and dilatancy of sheared granular\n  materials: Granular material exposed to shear shows a variety of unique phenomena:\nReynolds dilatancy, positional order and orientational order effects may\ncompete in the shear zone. We study granular packings consisting of macroscopic\nprolate, oblate and spherical grains and compare their behaviour. X-ray\ntomography is used to determine the particle positions and orientations in a\ncylindrical split bottom shear cell. Packing densities and the arrangements of\nindividual particles in the shear zone are evaluated. For anisometric\nparticles, we observe the competition of two opposite effects. One the one\nhand, the sheared granulate is dilated, but on the other hand the particles\nreorient and align with respect to the streamlines. Even though aligned\ncylinders in principle may achieve higher packing densities, this alignment\ncompensates for the effect of dilatancy only partially. The complex\nrearrangements lead to a depression of the surface above the well oriented\nregion while neigbouring parts still show the effect of dilation in the form of\nheaps. For grains with isotropic shapes, the surface remains rather flat.\nPerfect monodisperse spheres crystallize in the shear zone, whereby positional\norder partially overcompensates dilatancy effects. However, already slight\ndeviations from the ideal monodisperse sphere shape inhibit crystallization.",
        "positive": "Modulated nematic structures induced by chirality and steric\n  polarization: What kind of one-dimensional modulated nematic structures (ODMNS) can form\nnonchiral and chiral bent-core and dimeric materials? Here, using\nLandau-deGennes theory of nematics, extended to account for molecular steric\npolarization, we study a possibility of formation of ODMNS, both in nonchiral\nand intrinsically chiral liquid crystalline materials. Besides nematic and\ncholesteric phases, we find four bulk ODMNS for nonchiral materials, two of\nwhich have not been reported so far. These new structures are longitudinal\n($N_{LP}$) and transverse ($N_{TP}$) periodic waves where the polarization\nfield being periodic in one dimension stays parallel and perpendicular,\nrespectively, to the wave vector. The other two phases have all characteristic\nfeatures of the twist-bend nematic phase ($N_{TB}$) and the splay-bend nematic\nphase ($N_{SB}$), but their fine structure appears more complex than that\nconsidered so far. The presence of molecular chirality converts nonchiral\n$N_{TP}$ and $N_{SB}$ into new $N_{TB}$ phases. Interestingly, the nonchiral\n$N_{LP}$ phase can stay stable even in the presence of intrinsic molecular\nchirality. Exemplary phase diagrams provide further insights into the relative\nstability of these new modulated nematic structures."
    },
    {
        "anchor": "Expansion and rupture of charged microcapsules: We study the deformations of pH-responsive spherical microcapsules --\nmicrometer-scale liquid drops surrounded by thin, solid shells -- under the\ninfluence of electrostatic forces. When exposed to a large concentration of\nNaOH, the microcapsules become highly charged, and expand isotropically. We\nfind that the extent of this expansion can be understood by coupling\nelectrostatics with shell theory; moreover, the expansion dynamics is well\ndescribed by Darcy's law for fluid flow through the microcapsule shell.\nUnexpectedly, however, below a threshold NaOH concentration, the microcapsules\nbegin to disintegrate, and eventually rupture; they then expand non-uniformly,\nultimately forming large, jellyfish-like structures. Our results highlight the\nfascinating range of behaviors exhibited by pH-responsive microcapsules, driven\nby the interplay between electrostatic and mechanical forces.",
        "positive": "Empty smectics of hard nanorings: insights from a second-virial theory: Inspired by recent simulations on highly open liquid crystalline structures\nformed by rigid planar nanorings we present a simple theoretical framework\nexplaining the prevalence of smectic over nematic ordering in systems of\nring-shaped objects. The key part of our study is a calculation of the excluded\nvolume of such non-convex particles in the limit of vanishing thickness to\ndiameter ratio. Using a simple stability analysis we then show that dilute\nsystems of ring-shaped particles have a strong propensity to order into smectic\nstructures with an unusual antinematic order while solid disks of the same\ndimensions exhibit nematic order. Since our model rings have zero internal\nvolume these smectic structures are essential empty, resembling the strongly\nporous structures found in simulation. We argue that the antinematic\nintralamellar order of the rings plays an essential role in stabilizing these\nnovel smectic structures."
    },
    {
        "anchor": "Circular swimming motility and disordered hyperuniform state in an algae\n  system: Active matter comprises individually driven units that convert locally stored\nenergy into mechanical motion. Interactions between driven units lead to a\nvariety of non-equilibrium collective phenomena in active matter. One of such\nphenomena is anomalously large density fluctuations, which have been observed\nin both experiments and theories. Here we show that, on the contrary, density\nfluctuations in active matter can also be greatly suppressed. Our experiments\nare carried out with marine algae ($\\it{Effrenium\\ voratum}$) which swim in\ncircles at the air-liquid interfaces with two different eukaryotic flagella.\nCell swimming generates fluid flow which leads to effective repulsions between\ncells in the far field. Long-range nature of such repulsive interactions\nsuppresses density fluctuations and generates disordered hyperuniform states\nunder a wide range of density conditions. Emergence of hyperuniformity and\nassociated scaling exponent are quantitatively reproduced in a numerical model\nwhose main ingredients are effective hydrodynamic interactions and uncorrelated\nrandom cell motion. Our results demonstrate a new form of collective state in\nactive matter and suggest the possibility to use hydrodynamic flow for\nself-assembly in active matter.",
        "positive": "Using field theory to construct hybrid particle-continuum simulation\n  schemes with adaptive resolution for soft matter systems: We develop a multiscale hybrid scheme for simulations of soft condensed\nmatter systems, which allows one to treat the system at the particle level in\nselected regions of space, and at the continuum level elsewhere. It is derived\nsystematically from an underlying particle-based model by field theoretic\nmethods. Particles in different representation regions can switch\nrepresentations on the fly, controlled by a spatially varying tuning function.\nAs a test case, the hybrid scheme is applied to simulate colloid-polymer\ncomposites with high resolution regions close to the colloids. The hybrid\nsimulations are significantly faster than reference simulations of a pure\nparticle-based model, and the results are in good agreement."
    },
    {
        "anchor": "Nucleation Induced Undulative Instability in Thin Films of nCB Liquid\n  Crystals: A surface instability is reported in thin nematic films of 5CB and 8CB,\noccurring near the nematic--isotropic phase transition.\n  Although this instability leads to patterns reminiscent of spinodal\ndewetting, we show that it is actually based on a nucleation mechanism. Its\ncharacteristic wavelength does not depend markedly on film thickness, but\nstrongly on the heating rate.",
        "positive": "Casimir Dispersion Forces and Orientational Pairwise Additivity: A path integral formulation is used to study the fluctuation-induced\ninteractions between manifolds of arbitrary shape at large separations. It is\nshown that the form of the interactions crucially depends on the choice of the\nboundary condition. In particular, whether or not the Casimir interaction is\npairwise additive is shown to depend on whether the ``metallic'' boundary\ncondition corresponds to a ``grounded'' or an ``isolated'' manifold."
    },
    {
        "anchor": "Slippage of water past superhydrophobic carbon nanotube forests in\n  microchannels: We present in this letter an experimental characterization of liquid flow\nslippage over superhydrophobic surfaces made of carbon nanotube forests,\nincorporated in microchannels. We make use of a micro-PIV (Particule Image\nVelocimetry) technique to achieve the submicrometric resolution on the flow\nprofile necessary for accurate measurement of the surface hydrodynamic\nproperties. We demonstrate boundary slippage on the Cassie superhydrophobic\nstate, associated with slip lengths of a few microns, while a vanishing slip\nlength is found in the Wenzel state, when the liquid impregnates the surface.\nVarying the lateral roughness scale L of our carbon nanotube forest-based\nsuperhydrophobic surfaces, we demonstrate that the slip length varies linearly\nwith L in line with theoretical predictions for slippage on patterned surfaces.",
        "positive": "Transient sliding of thin hydrogel films: the role of poroelasticity: We report on the transient frictional response of contacts between a rigid\nspherical glass probe and a micrometer-thick poly(dimethylacrylamide) hydrogel\nfilm grafted onto a glass substrate when a lateral relative motion is applied\nto the contact initially at rest. From dedicated experiments with \\textit{in\nsitu} contact visualization, both the friction force and the contact size are\nobserved to vary well beyond the occurrence of a full sliding condition at the\ncontact interface. Depending on the imposed velocity and on the static contact\ntime before the motion is initiated, either an overshoot or an undershoot in\nthe friction force is observed. These observations are rationalized by\nconsidering that the transient is predominantly driven by the flow of water\nwithin the stressed hydrogel networks. From the development of a poroelastic\ncontact model using a thin film approximation, we provide a theoretical\ndescription of the main features of the transient. We especially justify the\nexperimental observation that the relaxation of friction force $F_t(t)$ toward\nsteady state is uniquely dictated by the time-dependence of the contact radius\n$a(t)$, independently on the sliding velocity and on the applied normal load."
    },
    {
        "anchor": "The influence of dielectric properties on van der Waals/Casimir forces\n  in solid-liquid systems: In this article we present calculations of van der Waals/Casimir forces,\ndescribed by Lifshitz theory, for the solid-liquid-solid system using measured\ndielectric functions of all involved materials for the wavelength range from\nmillimeters down to subnanometers. It is shown that even if the dielectric\nfunction is known over all relevant frequency ranges, the scatter in the\ndielectric data, can lead to very large scatter in the calculated van der\nWaals/Casimir forces. Especially when the liquid dielectric function becomes\ncomparable in magnitude to the dielectric function of one of the interacting\nsolids, the associated variation in the force can be up to a factor of two for\nplate-plate separations 5-500 nm. This corresponds to an uncertainty up to 100%\nin the theory prediction for a specific system. As a result accuracy testing of\nthe Lifshitz theory under these circumstances is rather questionable. Finally\nwe discuss predictions of Lifshitz theory regarding multiple\nrepulsive-attractive transitions with separation distance, as well as\nnontrivial scaling of the van der Waals/Casimir force with distance.",
        "positive": "Photoinduced reordering in thin azo-dye films and light-induced\n  reorientation dynamics of nematic liquid-crystal easy axis: We theoretically study the kinetics of photoinduced reordering triggered by\nlinearly polarized (LP) reorienting light in thin azo-dye films that were\ninitially illuminated with LP ultraviolet (UV) pumping beam. The process of\nreordering is treated as a rotational diffusion of molecules in the light\nintensity-dependent mean-field potential. The two dimensional diffusion model\nwhich is based on the free energy rotational Fokker-Planck equation and\ndescribes the regime of in-plane reorientation is generalized to analyze the\ndynamics of the azo-dye order parameter tensor at varying polarization azimuth\nof the reorienting light. It is found that, in the photosteady state, the\nintensity of LP reorienting light determines the scalar order parameter (the\nlargest eigenvalue of the order parameter tensor), whereas the steady state\norientation of the corresponding eigenvector (the in-plane principal axis)\ndepends solely on the polarization azimuth. We show that, under certain\nconditions, reorientation takes place only if the reorienting light intensity\nexceeds its critical value. Such threshold behavior is predicted to occur in\nthe bistability region provided that the initial principal axis lies in the\npolarization plane of reorienting light. The model is used to interpret the\nexperimental data on the light-induced azimuthal gliding of liquid-crystal easy\naxis on photoaligned azo-dye substrates."
    },
    {
        "anchor": "Domain Growth in the Active Model B: Critical and Off-critical\n  Composition: We study the ordering kinetics of an assembly of {\\it active Brownian\nparticles} (ABPs) on a two-dimensional substrate. We use a coarse-grained\nequation for the composition order parameter $\\psi ({\\bf r},t)$, where ${\\bf\nr}$ and $t$ denote space and time, respectively. The model is similar to the\n{\\it Cahn-Hilliard equation} or {\\it Model B} (MB) for a conserved order\nparameter with an additional activity term of strength $\\lambda$. This model\nhas been introduced by Wittkowski et al., Nature Comm. {\\bf 5}, 4351 (2014),\nand is termed {\\it Active Model B} (AMB). We study domain growth kinetics and\ndynamical scaling of the correlation function for the AMB with critical and\noff-critical compositions. The quantity $P = \\mbox{sign}(\\lambda \\times\n\\psi_0)$ governs the asymptotic growth kinetics for the off-critical AMB, where\n$\\psi_0$ denotes the average order parameter. For negative $P$, the domain\ngrowth law is the usual Lifshitz-Slyozov growth law with $L(t,\\lambda) \\sim\nt^{1/3}$. For positive $P$, the growth law shows a crossover to a novel growth\nlaw $L(t,\\lambda) \\sim t^{1/4}$. Further, the correlation function shows good\ndynamical scaling for the off-critical AMB but the scaling function has a\ndependency on $\\psi_0$ and $\\lambda$. We also study the effects of both\nadditive and multiplicative noise on the AMB.",
        "positive": "Phase Coexistence of Complex Fluids in Shear Flow: We present some results of recent calculations of rigid rod-like particles in\nshear flow, based on the Doi model. This is an ideal model system for\nexhibiting the generic behavior of shear-thinning fluids (polymer solutions,\nwormlike micelles, surfactant solutions, liquid crystals) in shear flow. We\npresent calculations of phase coexistence under shear among weakly-aligned\n(paranematic) and strongly-aligned phases, including alignment in the shear\nplane and in the vorticity direction (log-rolling). Phase coexistence is\npossible, in principle, under conditions of both common shear stress and common\nstrain rate, corresponding to different orientations of the interface between\nphases. We discuss arguments for resolving this degeneracy. Calculation of\nphase coexistence relies on the presence of inhomogeneous terms in the\ndynamical equations of motion, which select the appropriate pair of coexisting\nstates. We cast this condition in terms of an equivalent dynamical system, and\nexplore some aspects of how this differs from equilibrium phase coexistence."
    },
    {
        "anchor": "A Computational Model of Protein Induced Membrane Morphology with\n  Geodesic Curvature Driven Protein-Membrane Interface: Continuum or hybrid modeling of bilayer membrane morphological dynamics\ninduced by embedded proteins necessitates the identification of\nprotein-membrane interfaces and coupling of deformations of two surfaces. In\nthis article we developed (i) a minimal total geodesic curvature model to\ndescribe these interfaces, and (ii) a numerical one-one mapping between two\nsurface through a conformal mapping of each surface to the common middle\nannulus. Our work provides the first computational tractable approach for\ndetermining the interfaces between bilayer and embedded proteins. The one-one\nmapping allows a convenient coupling of the morphology of two surfaces. We\nintegrated these two new developments into the energetic model of\nprotein-membrane interactions, and developed the full set of numerical methods\nfor the coupled system. Numerical examples are presented to demonstrate (1) the\nefficiency and robustness of our methods in locating the curves with minimal\ntotal geodesic curvature on highly complicated protein surfaces, (2) the\nusefulness of these interfaces as interior boundaries for membrane deformation,\nand (3) the rich morphology of bilayer surfaces for different protein-membrane\ninterfaces.",
        "positive": "Specificity, flexibility and valence of DNA bonds guide emulsion\n  architecture: The specificity and thermal reversibility of DNA interactions have enabled\nthe self-assembly of crystal structures, self-replicating materials and\ncolloidal molecules. Grafting DNA onto liquid interfaces of emulsions leads to\nexciting new architectural possibilities due to the mobility of the DNA ligands\nand the patches they form between bound droplets. Here we show that the size\nand number of these adhesion patches (valency) can be controlled. Valence 2\nleads to flexible polymers of emulsion droplets, while valence above 4 leads to\nrigid droplet networks. A simple thermodynamic model quantitatively describes\nthe increase in the patch size with droplet radii, DNA concentration and the\nstiffness of the tether to the sticky-end. The patches are formed between\ndroplets with complementary DNA strands or alternatively with complementary\ncolloidal nanoparticles to mediate DNA binding between droplets. This emulsion\nsystem opens the route to directed self-assembly of more complex structures\nthrough distinct DNA bonds with varying strengths and controlled valence and\nflexibility."
    },
    {
        "anchor": "Breakdown of Hydrodynamics in the Radial Breathing Mode of a\n  Strongly-Interacting Fermi Gas: We measure the magnetic field dependence of the frequency and damping time\nfor the radial breathing mode of an optically trapped, Fermi gas of $^6$Li\natoms near a Feshbach resonance. The measurements address the apparent\ndiscrepancy between the results of Kinast et al., [Phys. Rev. Lett. {\\bf 92},\n150402 (2004)] and those of Bartenstein et al., [Phys. Rev. Lett. {\\bf 92},\n203201 (2004)]. Over the range of magnetic field from 770 G to 910 G, the\nmeasurements confirm the results of Kinast et al. Close to resonance, the\nmeasured frequencies are in excellent agreement with predictions for a unitary\nhydrodynamic gas. At a field of 925 G, the measured frequency begins to\ndecrease below predictions. For fields near 1080 G, we observe a breakdown of\nhydrodynamic behavior, which is manifested by a sharp increase in frequency and\ndamping rate. The observed breakdown is in qualitative agreement with the sharp\ntransition observed by Bartenstein et al., at 910 G.",
        "positive": "Theoretical modeling of polymer translocation: From the\n  electrohydrodynamics of short polymers to the fluctuating long polymers: The theoretical formulation of driven polymer translocation through nanopores\nis complicated by the combination of the pore electrohydrodynamics and the\nnonequilibrium polymer dynamics originating from the conformational polymer\nfluctuations. In this review, we discuss the modeling of polymer translocation\nin the distinct regimes of short and long polymers where these two effects\ndecouple. For the case of short polymers where polymer fluctuations are\nnegligible, we present a stiff polymer model including the details of the\nelectrohydrodynamic forces on the translocating molecule. We first show that\nthe electrohydrodynamic theory can accurately characterize the hydrostatic\npressure dependence of the polymer translocation velocity and time in\npressure-voltage-driven polymer trapping experiments. Then, we discuss the\nelectrostatic correlation mechanisms responsible for the experimentally\nobserved DNA mobility inversion by added multivalent cations in solid-state\npores, and the rapid growth of polymer capture rates by added monovalent salt\nin $\\alpha$-Hemolysin pores. In the opposite regime of long polymers where\npolymer fluctuations prevail, we review the iso-flux tension propagation (IFTP)\ntheory which can characterize the translocation dynamics at the level of single\nsegments. The IFTP theory is valid for a variety of polymer translocation and\npulling scenarios. We discuss the predictions of the theory for fully flexible\nand rodlike pore-driven and end-pulled translocation scenarios, where exact\nanalytic results can be derived for the scaling of the translocation time with\nchain length and driving force."
    },
    {
        "anchor": "Dynamic response of open cell dry foams: We study the mechanical response of an open cell dry foam subjected to\nperiodic forcing using experiments and theory. Using the measurements of the\nstatic and dynamic stress-strain relationship, we derive an over-damped model\nof the foam, as a set of infinitesimal non-linear springs, where the damping\nterm depends on the local foam strain. We then analyse the properties of the\nfoam when subjected to large amplitudes periodic stresses and determine the\nconditions for which the foam becomes optimally absorbing.",
        "positive": "Influence of charges on the behavior of polyelectrolyte microgels\n  confined to oil-water interfaces: The role of electrostatics on the interfacial properties of polyelectrolyte\nmicrogels has been discussed controversially in the literature. It is not yet\nclear if, or how, Coulomb interactions affect their behavior under interfacial\nconfinement. In this work, we combine compression isotherms, atomic force\nmicroscopy imaging, and computer simulations to further investigate the\nbehavior of pH-responsive microgels at oil-water interfaces. At low\ncompression, charged microgels can be compressed more than uncharged microgels.\nThe in-plane effective area of charged microgels is found to be smaller in\ncomparison to uncharged ones. Thus, the compressibility is governed by in-plane\ninteractions of the microgels with the interface. At high compression, however,\ncharged microgels are less compressible than uncharged microgels. Microgel\nfractions located in the aqueous phase interact earlier for charged than for\nuncharged microgels because of their different swelling perpendicular to the\ninterface. Therefore, the compressibility at high compression is controlled by\nout-of-plane interactions. In addition, the size of the investigated microgels\nplays a pivotal role. The charge-dependent difference in compressibility at low\ncompression is only observed for small but not for large microgels, while the\nbehavior at high compression does not depend on the size. Our results highlight\nthe complex nature of soft polymer microgels as compared to rigid colloidal\nparticles. We clearly demonstrate that electrostatic interactions affect the\ninterfacial properties of polyelectrolyte microgels."
    },
    {
        "anchor": "Giant negative mobility of inertial particles caused by the periodic\n  potential in steady laminar flows: Transport of an inertial particle advected by a two-dimensional steady\nlaminar flow is numerically investigated in the presences of a constant force\nand a periodic potential. Within particular parameter regimes this system\nexhibits absolute negative mobility, which means that the particle can travel\nin a direction opposite to the constant force. It is found that the profile of\nthe periodic potential plays an important role in the nonlinear response\nregime. Absolute negative mobility can be drastically enhanced by applying\nappropriate periodic potential, the parameter regime for this phenomenon\nbecomes larger and the amplitude of negative mobility grows exceedingly large\n(giant negative mobility). In addition, giant positive mobility is also\nobserved in the presence of appropriate periodic potential.",
        "positive": "Specific Adhesion of Membranes: Mapping to an Effective Bond Lattice Gas: We theoretically consider specific adhesion of a fluctuating membrane to a\nhard substrate via the formation of bonds between receptors attached to the\nsubstrate and ligands in the membrane. By integrating out the degrees of\nfreedom of the membrane shape, we show that in the biologically relevant limit\nspecific adhesion is well described by a lattice gas model, where lattice sites\ncorrespond to bond sites. We derive an explicit expression for the effective\nbond interactions induced by the thermal undulations of the membrane.\nFurthermore, we compare kinetic Monte Carlo simulations for our lattice gas\nmodel with full dynamic simulations that take into account both the shape\nfluctuations of the membrane and reactions between receptors and ligands at\nbond sites. We demonstrate that an appropriate mapping of the height dependent\nbinding and unbinding rates in the full scheme to rates in the lattice gas\nmodel leads to good agreement."
    },
    {
        "anchor": "Nonequilibrium steady states in fluids of platelike colloidal particles: Nonequilibrium steady states in an open system connecting two reservoirs of\nplatelike colloidal particles are investigated by means of a recently proposed\nphenomenological dynamic density functional theory [M. Bier and R. van Roij,\nPhys. Rev. E 76, 021405 (2007)]. The platelike colloidal particles are\napproximated within the Zwanzig model of restricted orientations, which\nexhibits an isotropic-nematic bulk phase transition. Inhomogeneities of the\nlocal chemical potential generate a diffusion current which relaxes to a\nnonvanishing value if the two reservoirs coupled to the system sustain\ndifferent chemical potentials. The relaxation process of initial states towards\nthe steady state turns out to comprise two regimes: a smoothening of initial\nsteplike structures followed by an ultimate relaxation of the slowest diffusive\nmode. The position of a nonequilibrium interface and the particle current of\nsteady states depend nontrivially on the structure of the reservoirs due to the\ncoupling between translational and orientational degrees of freedom of the\nfluid.",
        "positive": "Rigid cluster decomposition reveals criticality in frictional jamming: We study the nature of the frictional jamming transition within the framework\nof rigidity percolation theory. Slowly sheared frictional packings are\ndecomposed into rigid clusters and floppy regions with a generalization of the\npebble game including frictional contacts. We discover a second-order\ntransition controlled by the emergence of a system-spanning rigid cluster\naccompanied by a critical cluster size distribution. Rigid clusters also\ncorrelate with common measures of rigidity. We contrast this result with\nfrictionless jamming, where the rigid cluster size distribution is noncritical."
    },
    {
        "anchor": "Large-scale cortex-core structure formation in brain organoids: Brain organoids recapitulate a number of brain properties, including neuronal\ndiversity. However, do they recapitulate brain structure? Using a hydrodynamic\ndescription for cell nuclei as particles interacting initially via an\neffective, attractive force as mediated by the respective, surrounding\ncytoskeletons, we quantify structure development in brain organoids to\ndetermine what physical mechanism regulates the number of cortex-core\nstructures. Regions of cell nuclei overdensity in the linear regime drive the\ninitial seeding for cortex-core structures, which ultimately develop in the\nnon-linear regime, as inferred by the emergent form of an effective interaction\nbetween cell nuclei and with the extracellular environment, as mediated by a\ndynamic cytoskeleton. Individual cortex-core structures then provide a basis\nupon which we build an extended version of the buckling without bending\nmorphogenesis (BWBM) model, with its proliferating cortex and constraining\ncore, to predict foliations/folds of the cortex in the presence of a\nnonlinearity due to cortical cells actively regulating strain. In doing so, we\nobtain asymmetric foliations/folds with respect to the trough (sulci) and the\ncrest (gyri). In addition to laying new groundwork for the design of more\nfamiliar and less familiar brain structures, the hydrodynamic description for\ncell nuclei during the initial stages of brain organoid development provides an\nintriguing quantitative connection with large-scale structure formation in the\nuniverse.",
        "positive": "Viscoelastic fluid flow in a 2D channel bounded above by a deformable\n  finite thickness elastic wall: The steady flow of three viscoelastic fluids (Oldroyd-B, FENE-P, and Owens\nmodel for blood) in a two-dimensional channel, partly bound by a deformable,\nfinite thickness neo-Hookean solid, is computed. The limiting Weissenberg\nnumber beyond which computations fail to converge is found to increase with\nincreasing dimensionless solid elasticity parameter {\\Gamma}, following the\ntrend Owens > FENE- P > Oldroyd-B. The highly shear thinning nature of Owens\nmodel leads to the elastic solid always collapsing into the channel, for the\nwide range of values of {\\Gamma} considered here. In the case of the FENE-P and\nOldroyd-B models, however, the fluid-solid interface can be either within the\nchannel, or bulge outwards, depending on the value of {\\Gamma}. This behaviour\ndiffers considerably from predictions of earlier models that treat the\ndeformable solid as a zero-thickness membrane, in which case the membrane\nalways lies within the channel. The capacity of the solid wall to support both\npressure and shear stress, in contrast to the zero-thickness membrane that only\nresponds to pressure, is responsible for the observed difference. Compar- ison\nof the stress and velocity fields in the channel for the three viscoelastic\nfluids, with the predictions for a Newtonian fluid, reveals that shear thinning\nrather than elasticity is the key source of the observed differences in\nbehaviour."
    },
    {
        "anchor": "Beware of density dependent pair potentials: Density (or state) dependent pair potentials arise naturally from\ncoarse-graining procedures in many areas of condensed matter science. However,\ncorrectly using them to calculate physical properties of interest is subtle and\ncannot be uncoupled from the route by which they were derived. Furthermore,\nthere is usually no unique way to coarse-grain to an effective pair potential.\nEven for simple systems like liquid Argon, the pair potential that correctly\nreproduces the pair structure will not generate the right virial pressure.\nIgnoring these issues in naive applications of density dependent pair\npotentials can lead to an apparent dependence of thermodynamic properties on\nthe ensemble within which they are calculated, as well as other\ninconsistencies. These concepts are illustrated by several pedagogical\nexamples, including: effective pair potentials for systems with many-body\ninteractions, and the mapping of charged (Debye-H\\\"{u}ckel) and uncharged\n(Asakura-Oosawa) two-component systems onto effective one-component ones.",
        "positive": "Stretching Hookean ribbons Part I: relative edge extension underlies\n  transverse compression & buckling instability: The wrinkle pattern exhibited upon stretching a rectangular sheet has\nattracted considerable interest in the \"extreme mechanics\" community.\nNevertheless, key aspects of this notable phenomenon remain elusive.\nSpecifically -- what is the origin of the compressive stress underlying the\ninstability of the planar state? what is the nature of the ensuing bifurcation?\nhow does the shape evolve from a critical, near-threshold regime to a\nfully-developed pattern of parallel wrinkles that permeate most of the sheet?\nIn this paper we address some of these questions through numerical simulations\nand analytic study of the planar state in Hooekan sheets. We show that\ntransverse compression is a boundary effect, which originates from the relative\nextension of the clamped edges with respect to the transversely-contracted,\ncompression-free bulk of the sheet, and draw analogy between this edge-induced\ncompression and Moffatt vortices in viscous, cavity-driven flow. Next we\naddress the instability of the planar state and show that it gives rise to a\nbuckling pattern, localized near the clamped edges, which evolves -- upon\nincreasing the tensile load -- to wrinkles that invade the uncompressed portion\nof the sheet. Crucially, we show that the key aspects of the process -- from\nthe formation of transversely-compressed zones, to the consequent instability\nof the planar state and the emergence of a wrinkle pattern -- can be understood\nwithin a Hookean framework, where the only origin of nonlinear response is\ngeometric, rather than a non-Hookean stress-strain relation."
    },
    {
        "anchor": "Geometric scaling of purely-elastic flow instabilities: We present a combined experimental, numerical and theoretical investigation\nof the geometric scaling of the onset of a purely-elastic flow instability in a\nserpentine channel. Good qualitative agreement is obtained between experiments,\nusing dilute solutions of flexible polymers in microfluidic devices, and\ntwo-dimensional numerical simulations using the UCM model. The results are\nconfirmed by a simple theoretical analysis, based on the dimensionless\ncriterion proposed by Pakdel-McKinley for onset of a purely-elastic\ninstability.",
        "positive": "Evolution of displacements and strains in sheared amorphous solids: The local deformation of two-dimensional Lennard-Jones glasses under imposed\nshear strain is studied via computer simulations. Both the mean squared\ndisplacement and mean squared strain rise linearly with the length of the\nstrain interval $\\Delta \\gamma$ over which they are measured. However, the\nincrease in displacement does not represent single-particle diffusion. There\nare long-range spatial correlations in displacement associated with slip lines\nwith an amplitude of order the particle size. Strong dependence on system size\nis also observed. The probability distributions of displacement and strain are\nvery different. For small $\\Delta \\gamma$ the distribution of displacement has\na plateau followed by an exponential tail. The distribution becomes Gaussian as\n$\\Delta \\gamma$ increases to about .03. The strain distributions consist of\nsharp central peaks associated with elastic regions, and long exponential tails\nassociated with plastic regions. The latter persist to the largest $\\Delta\n\\gamma$ studied."
    },
    {
        "anchor": "Smectic Pores and Defect Cores: Riemann's minimal surfaces are a complete, embeddable, one-parameter family\nof minimal surfaces with translational symmetry along one direction. It's\ninfinite number of planar ends are joined together by an array of necks,\nclosely matching the morphology of a bicontinuous, lamellar system with pores\nconnecting alternating layers. We demonstrate explicitly that Riemann's minimal\nsurfaces are composed of a nonlinear sum of two oppositely-handed helicoids.\nThis description is particularly appropriate for describing smectic liquid\ncrystals containing two screw dislocations.",
        "positive": "Solid-like rheological response of non-entangled polymers in the molten\n  state: We show that non-entangled polymers display an elastic-like behaviour at a\nmacroscopic scale (probed at some 0.100 mm thickness) up to at least hundred\ndegrees above the glass transition temperature. This observation, found under\nnon-slippage conditions, both for side-chain liquid crystalline polymers and\nordinary polymers, is in contradiction with the typically found flow behaviour\nof polymer melt. Our measurements were carried out with a conventional\nrheometer at thicknesses of several tenths millimetres. Thus, we were probing\nbulk properties. The observed elasticity supposedly implies that even in the\nmelt the chains experience a cohesive effect of macroscopic distances,\ninvolving collective motions over time scales longer than the individual\nrelaxation time of an individual polymer chain. The detection of such a\nsolid-like property of molten non-entangled polymers is of considerable\nimportance for a better understanding of the polymer dynamics."
    },
    {
        "anchor": "Twisted quasiperiodic textures of biaxial nematics: Textures (i.e., smooth space non-uniform distributions of the order\nparameter) in biaxial nematics turned out to be much more difficult and\ninteresting than expected. Scanning the literature we find only a very few\npublications on this topic. Thus, the immediate motivation of the present paper\nis to develop a systematic procedure to study, classify and visualize possible\ntextures in biaxial nematics. Based on the elastic energy of a biaxial nematic\n(written in the most simple form that involves the least number of\nphenomenological parameters) we derive and solve numerically the Lagrange\nequations of the first kind. It allows one to visualize the solutions and\noffers a deep insight into their geometrical and topological features.\nPerforming Fourier analysis we find some particular textures possessing two or\nmore characteristic space periods (we term such solutions quasiperiodic ones\nbecause the periods are not necessarily commensurate). The problem is not only\nof intellectual interest but also of relevance to optical characteristics of\nthe liquid-crystalline textures.",
        "positive": "Physical entanglements mediate coherent motion of the active topological\n  glass confined within a spherical cavity: Motivated by chromosomes enclosed in nucleus and the recently discovered\nactive topological glass, we study a spherically confined melt of long\nnonconcatenated active polymer rings. Without activity, the rings exhibit the\nsame average large-scale conformational properties as chromatin fiber. Upon\nactivating consecutive monomer segments on the rings, the system arrives at a\nglassy steady state due to activity-enhanced topological constraints. The\nlatter generate coherent motions of the system, however the resulting\nlarge-scale structures are inconsistent with the fractal globule model. We\nobserve microphase separation between active and passive segments without\nsystematic trends in the positioning of active domains within the confining\nsphere. We find that tank-treading of active segments along the ring contour\nenhances active-passive phase separation in the state of active topological\nglass when both diffusional and conformational relaxation of the rings are\nsignificantly suppressed. Finally, although the present model of partly-active\nrings is not compatible with the large-scale chromatin organization, our\nresults suggest that the activity-enhanced entanglements that result in\nfacilitated intra- and inter-chromosomal contacts might be relevant for\nchromatin structure at smaller scales."
    },
    {
        "anchor": "Efficacy of information transmission in cellular communication: Inter and intra-cellular signaling are essential for individual cells to\nexecute various physiological tasks and accurately respond to changes in their\nenvironment. Signaling is carried out via diffusible molecules, the transport\nof which is often aided by active processes that provide directional advection.\nHow diffusion and advection together impact the accuracy of information\ntransmission during cell signaling remains less studied. To this end, we study\na one-dimensional model of cell signaling and compute the mutual information\n(MI) as a measure of information transmission. We find that the efficacy of the\ninformation transmission improves with advection only when the system\nparameters result in Peclet number greater than one. Intriguingly, MI exhibits\nnontrivial scaling with the Peclet number, characterized by three distinct\nregimes. We demonstrate that the observed dependence of MI on the transport\nproperties of signaling molecules has important consequences on cellular\ncommunication.",
        "positive": "Dielectric response of spherical particles of graded materials: We have studied the effective response of composites of spherical particles\nwith a dielectric profile which varies along the radius of the particles. We\ndeveloped a differential effective dipole theory to compute the dipole moment\nof individual spherical particle and hence the effective dielectric response of\na dilute suspension. The theory has been applied to two model dielectric\nprofiles. Moreover, we compare the approximate results with the exact results\nof the power-law profile and the agreement is excellent."
    },
    {
        "anchor": "Tethered membranes do not remain flat for strong structural asymmetry: We set up the statistical mechanics for a nearly flat, thermally equilibrated\nfluid membrane, attached to an elastic network through one of its sides. We\npredict that the resulting structural (inversion) asymmetry of the membrane,\nnotably due to the elastic network attached to one of its sides, can generate a\nlocal spontaneous curvature $C_0$, that may in turn destabilize the otherwise\nflat membrane. As $C_0$ rises above a threshold at a fixed temperature, a flat\ntethered membrane in the thermodynamic limit becomes structurally unstable,\nsignaling {\\em crumpling} of the flat membrane. In-vitro experiments on red\nblood cell membranes after depletion of adenosine-tri-phosphate molecules and\nartificial deposition of spectrin filaments on lipid bilayers may be used to\nverify our results.",
        "positive": "Flow-induced nonequilibrium self-assembly in suspensions of stiff,\n  apolar, active filaments: Active bodies in viscous fluids interact hydrodynamically through\nself-generated flows. Here we study spontaneous aggregation induced by\nhydrodynamic flow in a suspension of stiff, apolar, active filaments. Lateral\nhydrodynamic attractions in extensile filaments lead, independent of volume\nfraction, to anisotropic aggregates which translate and rotate ballistically.\nLateral hydrodynamic repulsion in contractile filaments lead, with increasing\nvolume fractions, to microstructured states of asters, clusters, and incipient\ngels where, in each case, filament motion is diffusive. Our results demonstrate\nthat the interplay of active hydrodynamic flows and anisotropic excluded volume\ninteractions provides a generic nonequilibrium mechanism for hierarchical\nself-assembly of active soft matter."
    },
    {
        "anchor": "Dynamic and programmable cellular-scale granules enable tissue-like\n  materials: Tissue-like materials are required in many robotic systems to improve\nhuman-machine interactions. However, the mechanical properties of living\ntissues are difficult to replicate. Synthetic materials are not usually capable\nof simultaneously displaying the behaviors of the cellular ensemble and the\nextracellular matrix. A particular challenge is identification of a cell-like\nsynthetic component which is tightly integrated with its matrix and also\nresponsive to external stimuli at the population level. Here, we demonstrate\nthat cellular-scale hydrated starch granules, an underexplored component in\nmaterials science, can turn conventional hydrogels into tissue-like materials\nwhen composites are formed. Using several synchrotron-based X-ray techniques,\nwe reveal the mechanically-induced motion and training dynamics of the starch\ngranules in the hydrogel matrix. These dynamic behaviors enable multiple\ntissue-like properties such as strain-stiffening, anisotropy, mechanical\nheterogeneity, programmability, mechanochemistry, impact absorption, and\nself-healability. The starch-hydrogel composites can be processed as robotic\nskins that maintain these tissue-like characteristics.",
        "positive": "Self-Diffusiophoresis in the Advection Dominated Regime: In both biological and artificial systems, concentration gradients can serve\nas a convenient mechanism for manipulating particles and generating motility.\nParticles that interact with a solute will move along its gradient; if they\nthemselves generate the gradient, this mechanism provides a means of\nself-propulsion. We consider a version of this type of motility appropriate to\ncertain biological systems where polymeric filaments provide the concentration\ngradient. As the filament diffusion is small, this corresponds to a regime of\nlarge P\\'eclet number where the motion is dominated by the effects of fluid\nadvection. The nature of such concentration-gradient-driven motion in the\nadvective regime differs in certain fundamental respects from the same process\nat low P\\'eclet number. In particular, we show that out of four broad scenarios\nof steady state motion at low P\\'eclet number, only two remain viable in the\nstrongly advecting limit."
    },
    {
        "anchor": "Electrorotation of a pair of spherical particles: We present a theoretical study of electrorotation (ER) of two spherical\nparticles under the action of a rotating electric field. When the two particles\napproach and finally touch, the mutual polarization interaction between the\nparticles leads to a change in the dipole moment of the individual particle and\nhence the ER spectrum, as compared to that of the well-separated particles. The\nmutual polarization effects are captured by the method of multiple images. From\nthe theoretical analysis, we find that the mutual polarization effects can\nchange the characteristic frequency at which the maximum angular velocity of\nelectrorotation occurs. The numerical results can be understood in the spectral\nrepresentation theory.",
        "positive": "Channel-Facilitated Molecular Transport Across Membranes: Attraction,\n  Repulsion and Asymmetry: Transport of molecules across membrane channels is investigated theoretically\nusing exactly solvable discrete stochastic site-binding models. It is shown\nthat the interaction potential between molecules and the channel has a strong\neffect on translocation dynamics. The presence of attractive binding sites in\nthe pore accelerates the particle current for small concentrations outside of\nthe membrane, while for large concentrations, surprisingly, repulsive binding\nsites produce the most optimal transport. In addition, asymmetry of the\ninteraction potential also strongly influences the channel transport. The\nmechanism of these phenomena are discussed using the details of particle\ndynamics at the binding sites."
    },
    {
        "anchor": "Phonon eigenfunctions of inhomogeneous lattices: Can you hear the shape\n  of a cone?: We study the phonon modes of interacting particles on the surface of a\ntruncated cone resting on a plane subject to gravity, inspired by recent\ncolloidal experiments. We derive the ground state configuration of the\nparticles under gravitational pressure in the small cone angle limit, and find\nan inhomogeneous triangular lattice with spatially varying density but robust\nlocal order. The inhomogeneity has striking effects on the normal modes such\nthat an important feature of the cone geometry, namely its apex angle, can be\nextracted from the lattice excitations. The shape of the cone leads to energy\ncrossings at long wavelengths and frequency-dependent quasi-localization at\nshort wavelengths. We analytically derive the localization domain boundaries of\nthe phonons in the limit of small cone angle and check our results with\nnumerical results for eigenfunctions.",
        "positive": "Emergence of highly-designable protein-backbone conformations in an\n  off-lattice model: Despite the variety of protein sizes, shapes, and backbone configurations\nfound in nature, the design of novel protein folds remains an open problem.\nWithin simple lattice models it has been shown that all structures are not\nequally suitable for design. Rather, certain structures are distinguished by\nunusually high designability: the number of amino-acid sequences for which they\nrepresent the unique ground state; sequences associated with such structures\npossess both robustness to mutation and thermodynamic stability. Here we report\nthat highly designable backbone conformations also emerge in a realistic\noff-lattice model. The highly designable conformations of a chain of 23 amino\nacids are identified, and found to be remarkably insensitive to model\nparameters. While some of these conformations correspond closely to known\nnatural protein folds, such as the zinc finger and the helix-turn-helix motifs,\nothers do not resemble known folds and may be candidates for novel fold design."
    },
    {
        "anchor": "Local and chain dynamics in miscible polymer blends: A Monte Carlo\n  simulation study: Local chain structure and local environment play an important role in the\ndynamics of polymer chains in miscible blends. In general, the friction\ncoefficients that describe the segmental dynamics of the two components in a\nblend differ from each other and from those of the pure melts. In this work, we\ninvestigate polymer blend dynamics with Monte Carlo simulations of a\ngeneralized bond-fluctuation model, where differences in the interaction\nenergies between non-bonded nearest neighbors distinguish the two components of\na blend. Simulations employing only local moves and respecting a non-bond\ncrossing condition were carried out for blends with a range of compositions,\ndensities, and chain lengths. The blends investigated here have long-chain\ndynamics in the crossover region between Rouse and entangled behavior. In order\nto investigate the scaling of the self-diffusion coefficients, characteristic\nchain lengths $N_\\mathrm{c}$ are calculated from the packing length of the\nchains. These are combined with a local mobility $\\mu$ determined from the\nacceptance rate and the effective bond length to yield characteristic\nself-diffusion coefficients $D_\\mathrm{c}=\\mu/N_\\mathrm{c}$. We find that the\ndata for both melts and blends collapse onto a common line in a graph of\nreduced diffusion coefficients $D/D_\\mathrm{c}$ as a function of reduced chain\nlength $N/N_\\mathrm{c}$. The composition dependence of dynamic properties is\ninvestigated in detail for melts and blends with chains of length twenty at\nthree different densities. For these blends, we calculate friction coefficients\nfrom the local mobilities and consider their composition and pressure\ndependence. The friction coefficients determined in this way show many of the\ncharacteristics observed in experiments on miscible blends.",
        "positive": "Alkali Atoms Attached to $^3$He Nanodroplets: We have experimentally studied the electronic $3p-> 3s$ excitation of Na\natoms attached to $^3$He droplets by means of laser-induced fluorescence as\nwell as beam depletion spectroscopy. From the similarities of the spectra\n(width/shift of absorption lines) with these of Na on $^4$He droplets, we\nconclude that sodium atoms reside in a ``dimple'' on the droplet surface and\nthat superfluid-related effects are negligible. The experimental results are\nsupported by Density Functional calculations at zero temperature, which confirm\nthe surface location of Na, K and Rb atoms on $^3$He droplets. In the case of\nNa, the calculated shift of the excitation spectra for the two isotopes is in\ngood agreement with the experimental data."
    },
    {
        "anchor": "Diffusion and spatial correlations in suspensions of swimming particles: Populations of swimming microorganisms produce fluid motions that lead to\ndramatically enhanced diffusion of tracer particles. Using simulations of\nsuspensions of swimming particles in a periodic domain, we capture this effect\nand show that it depends qualitatively on the mode of swimming: swimmers\n``pushed'' from behind by their flagella show greater enhancement than swimmers\nthat are ``pulled'' from the front. The difference is manifested by an\nincrease, that only occurs for pushers, of the diffusivity of passive tracers\nand the velocity correlation length with the size of the periodic domain. A\nphysical argument supported by a mean field theory sheds light on the origin of\nthese effects.",
        "positive": "Evidence of Raleigh-Hertz surface waves and shear stiffness anomaly in\n  granular media: Due to the non-linearity of Hertzian contacts, the speed of sound in granular\nmatter increases with pressure. Under gravity, the non-linear elastic\ndescription predicts that acoustic propagation is only possible through surface\nmodes, called Rayleigh-Hertz modes and guided by the index gradient. Here we\ndirectly evidence these modes in a controlled laboratory experiment and use\nthem to probe the elastic properties of a granular packing under vanishing\nconfining pressure. The shape and the dispersion relation of both transverse\nand sagittal modes are compared to the prediction of non-linear elasticity that\nincludes finite size effects. This allows to test the existence of a shear\nstiffness anomaly close to the jamming transition."
    },
    {
        "anchor": "Using evaporation to control capillary instabilities in micro-systems: The instabilities of fluid interfaces represent both a limitation and an\nopportunity for the fabrication of small-scale devices. Just as non-uniform\ncapillary pressures can destroy micro-electrical mechanical systems (MEMS), so\nthey can guide the assembly of novel solid and fluid structures. In many such\napplications the interface appears during an evaporation process and is\ntherefore only present temporarily. It is commonly assumed that this\nevaporation simply guides the interface through a sequence of equilibrium\nconfigurations, and that the rate of evaporation only sets the timescale of\nthis sequence. Here, we use Lattice-Boltzmann simulations and a theoretical\nanalysis to show that, in fact, the rate of evaporation can be a factor in\ndetermining the onset and form of dynamical capillary instabilities. Our\nresults shed light on the role of evaporation in previous experiments, and open\nthe possibility of exploiting diffusive mass transfer to directly control\ncapillary flows in MEMS applications.",
        "positive": "Glassy dynamics in three-dimensional embryonic tissues: Many biological tissues are viscoelastic, behaving as elastic solids on short\ntimescales and fluids on long timescales. This collective mechanical behavior\nenables and helps to guide pattern formation and tissue layering. Here we\ninvestigate the mechanical properties of three-dimensional tissue explants from\nzebrafish embryos by analyzing individual cell tracks and macroscopic\nmechanical response. We find that the cell dynamics inside the tissue exhibit\nfeatures of supercooled fluids, including subdiffusive trajectories and\nsignatures of caging behavior. We develop a minimal, three-parameter mechanical\nmodel for these dynamics, which we calibrate using only information about cell\ntracks. This model generates predictions about the macroscopic bulk response of\nthe tissue (with no fit parameters) that are verified experimentally, providing\na strong validation of the model. The best-fit model parameters indicate that\nalthough the tissue is fluid-like, it is close to a glass transition,\nsuggesting that small changes to single-cell parameters could generate a\nsignificant change in the viscoelastic properties of the tissue. These results\nprovide a robust framework for quantifying and modeling mechanically-driven\npattern formation in tissues."
    },
    {
        "anchor": "'Coffee-ring' patterns of polymer droplets: chain entanglement effect: Dried droplets of polymer solutions of different molecular weights and\nconcentrations leave various types of 'coffee-ring' patterns. These patterns\nare consequence of contact line motion. We have observed for very low molecular\nweight the droplet periphery part contains spheroidal structures whereas\ncentral part contains continuous layer. For higher molecular weight contact\nline exhibits 'stick-slip' motion. Whereas for very high molecular weight\ncontact line delays enough to start motion and finally moves uninterruptedly\nleaving a continuous layer of polymer. We have explained this phenomena in\nterms of chain entanglement which is resultant of molecular weight and solution\nconcentration. Depending on the entanglement chains can exhibit 'granular' and\n'collective' behavior even when monomer numbers remain same within the\ndroplets.",
        "positive": "Delayed nucleation in lipid particles: Metastable states in first-order phase-transitions have been traditionally\ndescribed by classical nucleation theory (CNT). However, recently an increasing\nnumber of systems displaying such a transition have not been successfully\nmodelled by CNT. The delayed crystallization of phospholipids upon\nsuper-cooling is an interesting case, since the extended timescales allow\naccess into the dynamics. Herein, we demonstrate the controllable behavior of\nthe long-lived metastable liquid-crystalline phase of\ndilauroyl-phosphatidylethanolamine (DLPE), arranged in multi-lamellar vesicles,\nand the ensuing cooperative transition to the crystalline state.\nExperimentally, we find that the delay in crystallization is a bulk phenomenon,\nwhich is tunable and can be manipulated to span two orders of magnitude in time\nby changing the quenching temperature, solution salinity, or adding a secondary\nphospholipid. Our results reveal the robust persistence of the metastability,\nand showcase the apparent deviation from CNT. This distinctive suppression of\nthe transition may be explained by the resistance of the multi-lamellar vesicle\nto deformations caused by nucleated crystalline domains. Since phospholipids\nare used as a platform for drug-delivery, a programmable design of cargo hold\nand release can be of great benefit."
    },
    {
        "anchor": "Homogeneous nucleation under shear in a two-dimensional Ising model:\n  cluster growth, coalescence and breakup: We compute rates and pathways for nucleation in a sheared two dimensional\nIsing model with Metropolis spin flip dynamics, using Forward Flux Sampling\n(FFS). We find a peak in the nucleation rate at intermediate shear rate. We\nanalyse the origin of this peak using modified shear algorithms and committor\nanalysis. We find that the peak arises from an interplay between three\nshear-mediated effects: shear-enhanced cluster growth, cluster coalescence and\ncluster breakup. Our results show that complex nucleation behaviour can be\nfound even in a simple driven model system. This work also demonstrates the use\nof FFS for simulating rare events, including nucleation, in nonequilibrium\nsystems.",
        "positive": "Defect self-propulsion in active nematic films with spatially-varying\n  activity: We study the dynamics of topological defects in active nematic films with\nspatially-varying activity and consider two setups: i) a constant activity\ngradient, and ii) a sharp jump in activity. A constant gradient of extensile\n(contractile) activity endows the comet-like $+1/2$ defect with a finite\nvorticity that drives the defect to align its nose in the direction of\ndecreasing (increasing) gradient. A constant gradient does not, however, affect\nthe known self-propulsion of the $+1/2$ defect and has no effect on the $-1/2$\nthat remains a non-motile particle. A sharp jump in activity acts like a wall\nthat traps the defects, affecting the translational and rotational motion of\nboth charges. The $+1/2$ defect slows down as it approaches the interface and\nthe net vorticity tends to reorient the defect polarization so that it becomes\nperpendicular to the interface. The $-1/2$ defect acquires a self-propulsion\ntowards the activity interface, while the vorticity-induced active torque tends\nto align the defect to a preferred orientation. This effective attraction of\nthe negative defects to the wall is consistent with the observation of an\naccumulation of negative topological charge at both active/passive interfaces\nand physical boundaries."
    },
    {
        "anchor": "Counter-ions at single charged wall: Sum rules: For inhomogeneous classical Coulomb fluids in thermal equilibrium, like the\njellium or the two-component Coulomb gas, there exists a variety of exact sum\nrules which relate the particle one-body and two-body densities. The necessary\ncondition for these sum rules is that the Coulomb fluid possesses good\nscreening properties, i.e. the particle correlation functions or the averaged\ncharge inhomogeneity, say close to a wall, exhibit a short-range (usually\nexponential) decay. In this work, we study equilibrium statistical mechanics of\nan electric double layer with counter-ions only, i.e. a globally neutral system\nof equally charged point-like particles in the vicinity of a plain hard wall\ncarrying a fixed uniform surface charge density of opposite sign. At large\ndistances from the wall, the one-body and two-body counter-ion densities go to\nzero slowly according to the inverse-power law. In spite of the absence of\nscreening, all known sum rules are shown to hold for two exactly solvable cases\nof the present system: in the weak-coupling Poisson-Boltzmann limit (in any\nspatial dimension larger than one) and at a special free-fermion coupling\nconstant in two dimensions. This fact indicates an extended validity of the sum\nrules and provides a consistency check for reasonable theoretical approaches.",
        "positive": "Microscopic Theory of Onset of De-Caging and Bond Breaking Activated\n  Dynamics in Ultra-Dense Fluids with Strong Short Range Attractions: We theoretically study thermally activated elementary dynamical processes\nthat precede full structural relaxation in ultra-dense particle liquids\ninteracting via strong short range attractive forces. Our approach is based on\na microscopic theory formulated at the particle trajectory level built on the\ndynamic free energy concept and an explicit treatment of how attractions\ncontrol physical bonding. Mean time scales for bond breaking, the early stage\nof cage escape, and a fixed non-Fickian displacement are analyzed in the\nrepulsive glass, bonded repulsive (attractive) glass, fluid, and dense gel\nregimes. The theory predicts a strong length-scale-dependent growth of these\ntime scales with attractive force strength at fixed packing fraction, a much\nweaker slowing down with density at fixed attraction strength, and a strong\ndecoupling of the shorter bond breaking time with the other two time scales\nthat are controlled mainly by perturbed steric caging. All results are in good\naccord with simulations, and additional testable predictions are made. The\nclassic statistical mechanical projection approximation of replacing all bare\nattractive and repulsive forces with a single effective force determined by\npair structure incurs major errors for describing processes associated with\nthermally activated escape from transiently localized states."
    },
    {
        "anchor": "A robust anisotropic hyperelastic formulation for the modelling of soft\n  tissue: The Holzapfel-Gasser-Ogden (HGO) model for anisotropic hyperelastic behaviour\nof collagen fibre reinforced materials was initially developed to describe the\nelastic properties of arterial tissue, but is now used extensively for\nmodelling a variety of soft biological tissues. Such materials can be regarded\nas incompressible, and when the incompressibility condition is adopted the\nstrain energy \\Psi of the HGO model is a function of one isotropic and two\nanisotropic deformation invariants. A compressible form (HGO-C model) is widely\nused in finite element simulations whereby the isotropic part of \\Psi is\ndecoupled into volumetric and isochoric parts and the anisotropic part of \\Psi\nis expressed in terms of isochoric invariants. Here, by using three simple\ndeformations (pure dilatation, pure shear and uniaxial stretch), we demonstrate\nthat the compressible HGO-C formulation does not correctly model compressible\nanisotropic material behaviour, because the anisotropic component of the model\nis insensitive to volumetric deformation due to the use of isochoric\nanisotropic invariants. In order to correctly model compressible anisotropic\nbehaviour we present a modified anisotropic (MA) model, whereby the full\nanisotropic invariants are used, so that a volumetric anisotropic contribution\nis represented. The MA model correctly predicts an anisotropic response to\nhydrostatic tensile loading, whereby a sphere deforms into an ellipsoid. It\nalso computes the correct anisotropic stress state for pure shear and uniaxial\ndeformation. To look at more practical applications, we developed a finite\nelement user-defined material subroutine for the simulation of stent deployment\nin a slightly compressible artery. Significantly higher stress triaxiality and\narterial compliance are computed when the full anisotropic invariants are used\n(MA model) instead of the isochoric form (HGO-C model).",
        "positive": "Generation of dynamic structures in nonequilibrium reactive bilayers: We present a nonequlibrium approach for the study of a flexible bilayer whose\ntwo components induce distinct curvatures. In turn, the two components are\ninterconverted by an externally promoted reaction. Phase separation of the two\nspecies in the surface results in the growth of domains characterized by\ndifferent local composition and curvature modulations. This domain growth is\nlimited by the effective mixing due to the interconversion reaction, leading to\na finite characteristic domain size. In addition to these effects, first\nintroduced in our earlier work [Phys. Rev. E {\\bf 71}, 051906 (2005)], the\nimportant new feature is the assumption that the reactive process actively\naffects the local curvature of the bilayer. Specifically, we suggest that a\nforce energetically activated by external sources causes a modification of the\nshape of the membrane at the reaction site. Our results show the appearance of\na rich and robust dynamical phenomenology that includes the generation of\ntraveling and/or oscillatory patterns. Linear stability analysis, amplitude\nequations and numerical simulations of the model kinetic equations confirm the\noccurrence of these spatiotemporal behaviors in nonequilibrium reactive\nbilayers."
    },
    {
        "anchor": "One-dimensional cluster growth and branching gels in colloidal systems\n  with short-range depletion attraction and screened electrostatic repulsion: We report extensive numerical simulations of a simple model for charged\ncolloidal particles in suspension with small non-adsorbing polymers. The chosen\neffective one-component interaction potential is composed of a short-range\nattractive part complemented by a Yukawa repulsive tail. We focus on the case\nwhere the screening length is comparable to the particle radius. Under these\nconditions, at low temperature, particles locally cluster into quasi\none-dimensional aggregates which, via a branching mechanism, form a macroscopic\npercolating gel structure. We discuss gel formation and contrast it with the\ncase of longer screening lengths, for which previous studies have shown that\narrest is driven by the approach to a Yukawa glass of spherical clusters. We\ncompare our results with recent experimental work on charged colloidal\nsuspensions [A. I. Campbell {\\it et al.} cond-mat/0412108, Phys. Rev. Lett. in\npress].",
        "positive": "Stress accumulation versus shape flattening in frustrated, warped-jigsaw\n  particle assemblies: Geometrically frustrated assembly has emerged as an attractive paradigm for\nunderstanding and engineering assemblies with self-limiting, finite equilibrium\ndimensions. We propose and study a novel 2D particle based on a so-called\n\"warped jigsaw\" (WJ) shape design: directional bonds in a tapered particle\nfavor curvature along multi-particle rows that frustrate 2D lattice order. We\ninvestigate how large-scale intra-assembly stress gradients emerge from the\nmicroscopic properties of the particles using a combination of numerical\nsimulation and continuum elasticity. WJ particles can favor anisotropic ribbon\nassemblies, whose lateral width may be self-limiting depending on the relative\nstrength of cohesive to elastic forces in the assembly, which we show to be\ncontrolled by the range of interactions and degree of shape misfit. The upper\nlimits of self-limited size are controlled by the crossover between two elastic\nmodes in assembly: the accumulation of shear with increasing width at small\nwidths giving way to unbending of preferred row curvature, permitting assembly\nto grow to unlimited sizes. We show that the stiffness controlling distinct\nelastic modes is governed by combination and placement of repulsive and\nattractive binding regions, providing a means to extend the range of\naccumulating stress to sizes that are far in excess of the single particle\nsize, which we corroborate via numerical studies of discrete particles of\nvariable interactions. Lastly, we relate the ground-state energetics of the\nmodel to lower and upper limits on equilibrium assembly size control set by the\nfluctuations of width along the ribbon boundary."
    },
    {
        "anchor": "Using Shape Diversity on the way to new Structure-Function Designs for\n  Magnetic Micropropellers: Synthetic microswimmers mimicking biological movements at the microscale have\nbeen developed in recent years. Actuating helical magnetic materials with a\nhomogeneous rotating magnetic field is one of the most widespread techniques\nfor propulsion at the microscale, partly because the actuation strategy\nrevolves around a simple linear relationship between the actuating field\nfrequency and the propeller velocity. However, the full control of the\nswimmers' motion has remained a challenge. Increasing the controllability of\nmicropropellers is crucial to achieve complex actuation schemes that in turn\nare directly relevant for numerous applications. The simplicity of the linear\nrelationship though limits the possibilities and flexibilities of swarm\ncontrol. Using a pool of randomly-shaped magnetic microswimmers, we show that\nthe complexity of shape can advantageously be translated into enhanced control.\nIn particular, directional reversal of sorted micropropellers is controlled by\nthe frequency of the actuating field. This directionality change is linked to\nthe balance between magnetic and hydrodynamic forces. We further show an\nexample how this behavior can experimentally lead to simple and effective\nsorting of individual swimmers from a group. The ability of these propellers to\nreverse swimming direction solely by frequency increases the control\npossibilities and is an example for propeller designs, where the complexity\nneeded for many applications is embedded directly in the propeller geometry\nrather than external factors such as actuation sequences.",
        "positive": "Effects of internal asymmetry on interface curvatures and outer drags\n  determining the oriented shift of the eccentric globules: The physical mechanism of the oriented shift and inverse of eccentric\nglobules in a modest extensional flow are investigated in this paper. Through\nthis work, a shift of the globule, which is driven mainly by the asymmetric\ninterfacial curvature, not by the outer drag, is disclosed. The asymmetric\nlayout of the daughter droplet leads to the asymmetric drags from the\ncontinuous phase and the asymmetric deformation of the globule with different\ninterface curvatures. As the inner droplet has both enhancing and suppressing\neffect on the globule deformation, the interface curvatures will vary when\nchanging the relative size and location of the inner droplet. This curvature\ndifference results in the asymmetric pressure distribution and circulation\ninside the globule. Eventually, the interaction of the inner driving force\n(pressure differences) and the outer drags causes the oriented shift and\ninverse of the globule. The shift direction is affected not only by the\nstructural asymmetry parameter (eccentricity), but also by some flow features\nsuch as the capillary number. The results obtained here might enlighten\npotential applications for the movement of soft globules driven by curvature\ndifferences."
    },
    {
        "anchor": "Growth Exponents with 3.99 Walkers: It is argued that the dielectric-breakdown model has an upper critical\n$\\eta_c$ equal to 4, for which the clusters become one-dimensional. A\nrenormalization group treatment of the model is presented near the critical\n$\\eta$.",
        "positive": "Thermoreversible Associating Polymer Networks: I. Interplay of\n  Thermodynamics, Chemical Kinetics, and Polymer Physics: Hybrid molecular dynamics/Monte Carlo simulations used to study melts of\nunentangled, thermoreversibly associating supramolecular polymers. In this\nfirst of a series of papers, we describe and validate a model that is effective\nin separating the effects of thermodynamics and chemical kinetics on the\ndynamics and mechanics of these systems, and is extensible to arbitrarily\nnonequilibrium situations and nonlinear mechanical properties. We examine the\nmodel's quiescent (and heterogeneous) dynamics, nonequilibrium chemical\ndynamics, and mechanical properties. Many of our results may be understood in\nterms of the crossover from diffusion-limited to kinetically-limited sticky\nbond recombination, which both influences and is influenced by polymer physics,\ni. e. the connectivity of the parent chains."
    },
    {
        "anchor": "Effect of surface roughness and adsorbates on superlubricity: We study the sliding of elastic solids in adhesive contact with flat and\nrough interfaces. We consider the dependence of the sliding friction on the\nelastic modulus of the solids. For elastically hard solids with planar surfaces\nwith incommensurate surface structures we observe extremely low friction\n(superlubricity), which very abruptly increases as the elastic modulus\ndecreases. We show that even a relatively small surface roughness or a low\nconcentration of adsorbates may completely kill the superlubricity state.",
        "positive": "Dynamics of patchy particles in and out of equilibrium: We combine particle-based simulations, mean-field rate equations, and\nWertheim's theory to study the dynamics of patchy particles in and out of\nequilibrium, at different temperatures and densities. We consider an initial\nrandom distribution of non-overlapping three-patch particles, with no bonds,\nand analyze the time evolution of the breaking and bonding rates of a single\nbond. We find that the asymptotic (equilibrium) dynamics differs from the\ninitial (out of equilibrium) one. These differences are expected to depend on\nthe initial conditions, temperature, and density."
    },
    {
        "anchor": "Viscometric flow of dense granular materials under controlled pressure\n  and shear stress: This study examines the flow of dense granular materials under external shear\nstress and pressure using discrete element method simulations. In this method,\nthe material is allowed to strain along all periodic directions and adapt its\nsolid volume fraction in response to an imbalance between the internal state of\nstress and the external applied stress. By systematically varying the external\nshear stress and pressure, the steady rheological response is simulated for:\n(1) rate-independent quasi-static flow; and (2) rate-dependent inertial flow.\nThe simulated flow is viscometric with non-negligible first and second normal\nstress differences. While both normal stress differences are negative in\ninertial flows, the first normal stress difference switches from negative to\nslightly positive, and second normal stress difference tends to zero in\nquasi-static flows. The first normal stress difference emerges from a lack of\ncoaxiality between a second-rank contact fabric tensor and strain rate tensor\nin the flow plane, while the second normal stress difference is linked to an\nexcess of contacts in the shear plane compared with the vorticity direction. A\ngeneral rheological model of second order (in terms of strain rate tensor) is\nproposed to describe the two types of flow, and the model is calibrated for\nvarious values of interparticle friction from simulations on nearly\nmonodisperse spheres. The model incorporates normal stress differences in both\nregimes of flow and provides a complete viscometric description of steady dense\ngranular flows.",
        "positive": "Emergence of a hexagonal pattern in shear-thickening suspensions under\n  orbital oscillations: Dense particle suspension under shear may lose its uniform state to large\nlocal density and stress fluctuations, which challenge the mean-field\ndescription of the system. Here, we explore the novel dynamics of a\nnon-Brownian suspension under orbital oscillations, where localized density\nwaves along the flow direction appear beyond an excitation frequency threshold\nand self-organize into a hexagonal pattern across the system. The spontaneous\noccurrence of the inhomogeneity pattern arises from a coupling between particle\nadvection and the shear-thickening nature of the suspension. Through linear\nstability analysis, we show that they overcome the stabilizing effects of\nparticle pressure at sufficient particle volume fraction and oscillation\nfrequency. In addition, the long-standing density waves degenerate into random\nfluctuations when replacing the free surface with rigid confinement. It\nindicates that the shear-thickened state is intrinsically heterogeneous, and\nthe boundary conditions are crucial for developing local disturbance."
    },
    {
        "anchor": "A Tetris-like Model Showing a Universal Enhanced Flow Rate of a Hopper\n  Discharging Hard Discs Through an Adjustable Inclusion: In the literature, placing an inclusion near the orifice of a hopper,\ncontaining disc particles, has been experimentally and numerically reported to\nlocally enhance the gravity-driven hopper flow rate. Moreover, the peaked flow\nrate can happen regardless of the interparticle friction, the inclusion\ngeometry, or the disc dispersity. To reveal the fundamental reason causing this\nlocal effect, we propose a Tetris-like model that sequentially moves one disc\nparticle at a time towards the hopper orifice. A Gaussian displacement function\nthat independently controls a disc's movement in the horizontal or vertical\ndirection, and the algorithm of the model accepts a movement as long as it\ncreates no overlap between objects in the system. Our model creates an\nartificial steady probability-driven hopper flow without knowing the Newtonian\ndynamics which allows interparticle collaborative motion. Under specific\nconditions, we reproduce the enhanced flow rate and show that a moderate\nresponse time of the system and a flow rate difference between its value around\nthe inclusion and its maximum without an inclusion are sufficient to explain\nthis local effect with no Newton's laws involved.",
        "positive": "Why does high pressure destroy co-non-solvency of PNIPAm in aqueous\n  methanol?: It is well known that poly(N-isopropylacrylamide) (PNIPAm) exhibits an\ninteresting, yet puzzling, phenomenon of co-non-solvency. Co-non-solvency\noccurs when two competing good solvents for PNIPAm, such as water and alcohol,\nare mixed together. As a result, the same PNIPAm collapses within intermediate\nmixing ratios. This complex conformational transition is driven by preferential\nbinding of methanol with PNIPAm. Interestingly, co-non-solvency can be\ndestroyed when applying high hydrostatic pressures. In this work, using a large\nscale molecular dynamics simulation employing high pressures, we propose a\nmicroscopic picture behind the suppression of the co-non-solvency phenomenon.\nBased on thermodynamic and structural analysis, our results suggest that the\npreferential binding of methanol with PNIPAm gets partially lost at high\npressures, making the background fluid reasonably homogeneous for the polymer.\nThis is consistent with the hypothesis that the co-non-solvency phenomenon is\ndriven by preferential binding and is not based on depletion effects."
    },
    {
        "anchor": "Correlation and cross-linking effects in imprinting sites for divalent\n  adsorption in gels: This paper has been withdrawn by the author(s), as required by JPC-Journal of\nPhysical Chemistry for reasons of publication.",
        "positive": "Statics and inertial dynamics of a ruck in a rug: We consider the familiar problem of a bump, or ruck, in a rug. Under lateral\ncompression, a rug bends out of the plane forming a ruck -- a localized region\nin which it is no longer in contact with the floor. We show that when the\nexternal force that created the ruck is removed, the ruck flattens out unless\nthe initial compression is greater than a critical value, which we determine.\nWe also study the inertial motion of a ruck that is generated when one end of\nthe rug is moved rapidly. We show that the equations of motion admit a\ntravelling ruck solution for which a linear combination of the tension and\nkinetic energy is determined by the ruck size. We confirm these findings\nexperimentally. We end by discussing the potential implications of our work for\nthe analogous propagation of localized slip pulses in the sliding of two bodies\nin contact."
    },
    {
        "anchor": "Shear zones and wall slip in the capillary flow of concentrated\n  colloidal suspensions: We image the flow of a nearly random close packed, hard-sphere colloidal\nsuspension (a `paste') in a square capillary using confocal microscopy. The\nflow consists of a `plug' in the center while shear occurs localized adjacent\nto the channel walls, reminiscent of yield-stress fluid behavior. However, the\nobserved scaling of the velocity profiles with the flow rate strongly contrasts\nyield-stress fluid predictions. Instead, the velocity profiles can be captured\nby a theory of stress fluctuations originally developed for chute flow of dry\ngranular media. We verified this behavior both for smooth and rough boundary\nconditions.",
        "positive": "Modified Poisson-Boltzmann theory for polyelectrolytes in monovalent\n  salt solutions with finite-size ions: We present a soft-potential-enhanced Poisson-Boltzmann (SPB) theory to\nefficiently capture ion distributions and electrostatic potential around\nrodlike charged macromolecules. The SPB model is calibrated with a\ncoarse-grained particle-based model for polyelectrolytes (PEs) in monovalent\nsalt solutions as well as compared to a full atomistic molecular dynamics\nsimulations with explicit solvent. We demonstrate that our modification enables\nthe SPB theory to accurately predict monovalent ion distributions around a\nrodlike PE in a wide range of ion and charge distribution conditions in the\nweak-coupling regime. These include excess salt concentrations up to 1 M, and\nion sizes ranging from small ions, such as Na or Cl, to softer and larger ions\nwith size comparable to the PE diameter. The work provides a simple way to\nimplement an enhancement that effectively captures the influence of ion size\nand species into the PB theory in the context of PEs in aqueous salt solutions."
    },
    {
        "anchor": "Electrorotation in graded colloidal suspensions: Biological cells can be treated as composites of graded material inclusions.\n  In addition to biomaterials, graded composites are important in more\ntraditional materials science. In this article, we investigate the\nelectrorotation (ER) spectrum of a graded colloidal suspension in an attempt to\ndiscuss its dielectric properties. For that, we use the recently obtained\ndifferential effective dipole approximation (DEDA) and generalize it for\nnon-spherical particles. We find that variations in the conductivity profile\nmay make the characteristic frequency red-shifted and have also an effect on\nthe rotation peak. On the other hand, variations in the dielectric profile may\nenhance the rotation peak, but do not have any significant effect on the\ncharacteristic frequency. In the end, we apply our theory to fit experimental\ndata obtained for yeast cells and find good agreement.",
        "positive": "Competition between rotation and turbulence in superfluid He$^4$: Two types of vortex states have been much studied in superfluid $^4$He. The\nfirst is the vortex array in a rotating container. The second is the vortex\ntangle in turbulent flow. An experiment attempt to combine these two states by\nrotating a counterflow was attempted years ago. The data suggest the existence\nof different flow regimes separated by instabilities, but a theoretical\ninterpretation is still missing. We present work in which we use the vortex\nfilament model to numerically investigate rotating counterflow. We show\nevidence of a new state of polarized turbulence."
    },
    {
        "anchor": "Effect of topology on the collapse transition and the instantaneous\n  shape of a model heteropolymer: The effect of topology on the collapse transition and instantaneous shape of\nan energy polydisperse polymer (a model heteropolymer) is studied by means of\ncomputer simulations. In particular, we consider three different chain\ntopology, namely, linear (L), ring (R) and trefoil knot (T). The heteropolymer\nis modeled by assigning each monomer an interaction parameter, $\\varepsilon_i$,\ndrawn randomly from a Gaussian distribution. Through chain size scaling the\ntransition temperature, $\\theta$, is located and compared among the chains of\ndifferent topogies. The influence of topology is reflected in the value of\n$\\theta$ and observed that $\\theta(\\text{L}) > \\theta(\\text{R}) >\n\\theta(\\text{T})$ in a similar fashion to that of the homopolymer counterpart.\nAlso studied chain size distributions, and the shape changes across the\ntransition temperature characterised through shape parameters based on the\neigenvalues of the gyration tensor. It is observed that, for the model\nheteropolymer, in addition to chain topology the $\\theta$-temperature also\ndepends on energy polydispersity.",
        "positive": "Coupling of Two Motor Proteins: a New Motor Can Move Faster: We study the effect of a coupling between two motor domains in\nhighly-processive motor protein complexes. A simple stochastic discrete model,\nin which the two parts of the protein molecule interact through some energy\npotential, is presented. The exact analytical solutions for the dynamic\nproperties of the combined motor species, such as the velocity and dispersion,\nare derived in terms of the properties of free individual motor domains and the\ninteraction potential. It is shown that the coupling between the motor domains\ncan create a more efficient motor protein that can move faster than individual\nparticles. The results are applied to analyze the motion of helicase RecBCD\nmolecules."
    },
    {
        "anchor": "In silico modeling of the rheological properties of covalently\n  crosslinked collagen triple helices: Biomimetic hydrogels based on natural polymers are a promising class of\nbiomaterial, mimicking the natural extra-cellular matrix of biological tissues\nand providing cues for cell attachment, proliferation and differentiation. With\na view to providing an upstream method to guide subsequent experimental design,\nthe aim of this study was to introduce a mathematical model that described the\nrheological properties of a hydrogel system based on covalently crosslinked\ncollagen triple helices. In light of their organization, such gels exhibit\nlimited collagen bundling that cannot be described by existing fibril network\nmodels. The model presented here treats collagen triple helices as discrete\nsemi-flexible polymers, permits full access to metrics for network\nmicrostructure, and should provide a comprehensive understanding of the\nparameter space associated with the development of such multi-functional\nmaterials. Triple helical hydrogel networks were experimentally obtained via\nreaction of type I collagen with both aromatic and aliphatic diacids. The\ncomplex modulus G* was found from rheological testing in linear shear and\nquantitatively compared to model predictions. In silico data from the\ncomputational model successfully described the experimental trends in hydrogel\nstorage modulus with either (i) the concentration of collagen triple helices\nduring crosslinking reaction or (ii) the type of crosslinking segment\nintroduced in resulting hydrogel networks. This approach may pave the way to a\nstep change in the rational design of biomimetic triple helical collagen\nsystems with controlled multi-functionality.",
        "positive": "The Geometrical Structure of Disordered Sphere Packings: The three dimensional structure of large packings of monosized spheres with\nvolume fractions ranging between 0.58 and 0.64 has been studied with X-ray\nComputed Tomography. We search for signatures of organization, we classify\nlocal arrangements and we explore the effects of local geometrical constrains\non the global packing. This study is the largest and the most accurate\nempirical analysis of disordered packings at the grain-scale to date with over\n140,000 sphere coordinates mapped. We discuss topological and geometrical ways\nto characterize and classify these systems, and discuss implications that local\ngeometry can have on the mechanisms of formation of these amorphous structures."
    },
    {
        "anchor": "Many-body interactions and correlations in coarse-grained descriptions\n  of polymer solutions: We calculate the two, three, four, and five-body (state independent)\neffective potentials between the centers of mass (CM) of self avoiding walk\npolymers by Monte-Carlo simulations. For full overlap, these coarse-grained\nn-body interactions oscillate in sign as (-1)^n, and decrease in absolute\nmagnitude with increasing n. We find semi-quantitative agreement with a scaling\ntheory, and use this to discuss how the coarse-grained free energy converges\nwhen expanded to arbitrary order in the many-body potentials. We also derive\neffective {\\em density dependent} 2-body potentials which exactly reproduce the\npair-correlations between the CM of the self avoiding walk polymers. The\ndensity dependence of these pair potentials can be largely understood from the\neffects of the {\\em density independent} 3-body potential. Triplet correlations\nbetween the CM of the polymers are surprisingly well, but not exactly,\ndescribed by our coarse-grained effective pair potential picture. In fact, we\ndemonstrate that a pair-potential cannot simultaneously reproduce the two and\nthree body correlations in a system with many-body interactions. However, the\ndeviations that do occur in our system are very small, and can be explained by\nthe direct influence of 3-body potentials.",
        "positive": "Symmetry effects in electrostatic interactions between two arbitrarily\n  charged spherical shells in the Debye-H\u00fcckel approximation: Inhomogeneous charge distributions have important repercussions on\nelectrostatic interactions in systems of charged particles but are often\ndifficult to examine theoretically. We investigate how electrostatic\ninteractions are influenced by patchy charge distributions exhibiting certain\npoint group symmetries. We derive a general form of the electrostatic\ninteraction energy of two permeable, arbitrarily charged spherical shells in\nthe Debye-H\\\"uckel approximation and apply it to the case of particles with\nicosahedral, octahedral, and tetrahedral inhomogeneous charge distributions. We\nanalyze in detail how charge distribution symmetry modifies the interaction\nenergy and find that local charge inhomogeneities reduce the repulsion of two\noverall equally charged particles, while sufficient orientational variation in\nthe charge distribution can turn the minimum interaction energy into an\nattraction. Additionally we show that larger patches and thus lower symmetries\nand wave numbers result in bigger attraction given the same variation."
    },
    {
        "anchor": "Chemical ordering in Pd$_{81}$Ge$_{19}$ metallic glass studied by\n  reverse Monte-Carlo modelling of XRD, ND and EXAFS experimental data: Pd$_{81}$Ge$_{19}$ metallic glass was investigated by neutron diffraction,\nX-ray diffraction and extended X-ray absorption fine structure spectroscopy\n(EXAFS) at the Ge K-edge. Large scale structural models were obtained by\nfitting the three measurements simultaneously in the framework of the reverse\nMonte Carlo simulation technique. It was found that the experimental data sets\ncan be adequately fitted without Ge-Ge nearest neighbours. Mean Pd-Pd and Pd-Ge\ndistances are 2.80$\\pm$0.02 {\\AA} and 2.50$\\pm$0.02 {\\AA}, respectively. The\ntotal average coordination number of Pd is 12.1$\\pm$0.5 while Ge is surrounded\nby 10.6$\\pm$1.1 Pd atoms. The coordination numbers calculated from partial pair\ncorrelation functions were compared to those obtained by Voronoi tessellation\nmethod. It was found that the latter technique overestimates the number of\nnearest neighbours by about 20% due to the significant contribution of distant\npairs.",
        "positive": "\"Cracking-the-whip\" effect stretches driven polymers: Cracking the whip accelerates the tail of a chain to hit the air loudly and\nclearly. We proved that the similar acceleration effect causes coil deformation\nof driven chain-like polymers. We first preformed Monte Carlo simulations of a\nsingle driven polymer coil to demonstrate its deformation in company with\nfaster or slower deviations of velocities. We then performed parallel Brownian\nDynamics simulations to demonstrate that the coil deformation can be caused by\nthe so-called \"cracking-the-whip\" effect due to non-synchronous biased Brownian\nmotions of monomers inherited in Monte Carlo simulations. Since such\nnon-synchronous motions represent random perturbations in the environmentally\ndependent potential energy landscape or mobility, reflecting heterogeneous\ndynamics of polymers in the liquid phase, our observations bring new insights\ninto the non-linear dynamics of driven chain-like polymers."
    },
    {
        "anchor": "Electrostatic Contribution to Twist Rigidity of DNA: The electrostatic contribution to twist rigidity of DNA is studied, and it is\nshown that the Coulomb self-energy of the double-helical sugar-phosphate\nbackbone contributes considerably to twist rigidity of DNA--the electrostatic\ntwist rigidity of DNA is found as $C_{\\rm elec}\\approx 5$ nm, which makes up\nabout 7% of its total twist rigidity ($C_{\\rm DNA}\\approx 75$ nm). The\nelectrostatic twist rigidity is found, however, to only weakly depend on the\nsalt concentration, because of a competition between two different screening\nmechanisms: (1) Debye screening by the salt ions in the bulk, and (2)\nstructural screening by the periodic charge distribution along the backbone of\nthe helical polyelectrolyte. It is found that depending on the parameters, the\nelectrostatic contribution could stabilize or destabilize the structure of a\nhelical polyelectrolyte.",
        "positive": "Tuning flow asymmetry with bio-inspired soft leaflets: In Nature, liquids often circulate in channels textured with leaflets, cilia\nor porous walls that deform with the flow. These soft structures are optimized\nto passively control flows and inspire the design of novel microfluidic and\nsoft robotic devices. Yet so far the relationship between the geometry of the\nsoft structures and the properties of the flow remains poorly understood. Here,\ntaking inspiration from the lymphatic system, we devise millimetric scale\nfluidic channels with asymmetric soft leaflets that passively increase (reduce)\nthe channel resistance for forward (backward) flows. Combining experiments,\nnumerics and analytical theory, we show that tuning the geometry of the\nleaflets controls the flow properties of the channel through an interplay\nbetween asymmetry and nonlinearity. In particular, we find the conditions for\nwhich flow asymmetry is maximal. Our results open the way to a better\ncharacterization of biological leaflet malformations and to more accurate\ncontrol of flow orientation and pumping mechanisms for microfluidics and soft\nrobotic systems."
    },
    {
        "anchor": "Three-body interactions in complex fluids: virial coefficients from\n  simulation finite-size effects: A simulation technique is described for quantifying the contribution of\nthree-body interactions to the thermodynamical properties of coarse-grained\nrepresentations of complex fluids. The method is based on comparing the third\nvirial coefficient $B_3$ for a complex fluid with that of an approximate\ncoarse-grained model described by a pair potential. To obtain $B_3$ we\nintroduce a new technique which expresses its value in terms of the measured\nvolume-dependent asymptote of a certain structural function. The strategy is\napplicable to both Molecular Dynamics and Monte Carlo simulation. Its utility\nis illustrated via measurements of three-body effects in models of star polymer\nand highly size-asymmetrical colloid-polymer mixtures.",
        "positive": "Granular Convection in Microgravity: We investigate the role of gravity on convection in a dense granular shear\nflow. Using a microgravity modified Taylor-Couette shear cell under the\nconditions of parabolic flight microgravity, we demonstrate experimentally that\nsecondary, convective-like flows in a sheared granular material are close to\nzero in microgravity and enhanced under high-gravity conditions, though the\nprimary flow fields are unaffected by gravity. We suggest that gravity tunes\nthe frictional particle-particle and particle-wall interactions, which have\nbeen proposed to drive the secondary flow. In addition, the degree of plastic\ndeformation increases with increasing gravitational forces, supporting the\nnotion that friction is the ultimate cause."
    },
    {
        "anchor": "Increase of cationic concentration due to bending of overcharged DNA in\n  strong Coulomb coupling regime: This study reveals that, in strong coulomb coupling regime, bending a\nstraight and fully overcharged DNA (up to its maximal acceptance by multivalent\ncounterions) to a circle releases some of the adsorbed (correlated)counterions\nbut still remains fully overcharged. This phenomenon seems to be inherent to\nthe minimum energy state of a DNA. By definition, the total electrostatic\npotential energy of a macroion-counterion system reaches to its lowest point at\nmaximal acceptance of overcharging counterions that ensures the most stable\nconformation. This intermediate phenomenon of release of cations from DNA\nsurface due to bending can be taken into account in theoretical modeling of\nsome ionic concentration dependent physico-chemical aspects of DNA solutions in\nstrong Coulomb coupling regimes.",
        "positive": "A homogenization theory for systems of penetrable dielectric particles: A many-particle theory is presented for the effective quasistatic\npermittivity of macroscopically homogeneous and isotropic systems of\ninhomogeneous dielectric particles with different degrees of penetrability. The\ntheory is based upon our original compact-group approach, complemented by the\nHashin-Shtrikman variational principle. The governing equation is obtained by\nsumming up the statistical moments for the deviations of the local permittivity\nin the system from the desired effective permittivity. The latter is, in\nprinciple, recoverable from the governing equation as a functional of the\nconstituents' volume concentrations (expressed through statistical averages of\ncertain products of the particles' characteristic functions) and permittivity\nprofiles. Under the suggestion that the local permittivity is determined by the\nshortest distance from the point of interest to the nearest sphere, a complete\nanalysis is carried out for hard and fully penetrable spheres with\npiecewise-continuous radial permittivities. The results are contrasted with\nother authors' analytical theories and simulation data. This comparison\nvalidates our theory and also sheds light on possible computational errors\ncaused by the use of rectangular lattices to simulate dispersions of spherical\nparticles."
    },
    {
        "anchor": "Structure and rheological properties of model microemulsion networks\n  filled with nanoparticles: Model microemulsion networks of oil droplets stabilized by non ionic\nsurfactant and telechelic polymer C18-PEO(10k)-C18 have been studied for two\ndroplet-to-polymer size ratios. The rheological properties of the networks have\nbeen measured as a function of network connectivity and can be described in\nterms of simple percolation laws. The network structure has been characterised\nby Small Angle Neutron Scattering. A Reverse Monte Carlo approach is used to\ndemonstrate the interplay of attraction and repulsion induced by the copolymer.\nThese model networks are then used as matrix for the incorporation of silica\nnanoparticles (R=10nm), individual dispersion being checked by scattering. A\nstrong impact on the rheological properties is found for silica volume\nfractions up to 9%.",
        "positive": "Quantitative understanding of the onset of dense granular flows: The question when and how dense granular materials start to flow under\nstress, despite many industrial and geophysical applications, remains largely\nunresolved. We develop and test a simple equation for the onset of quasi-static\nflows of granular materials which is based on the frictional aging of the\ngranular packing. The result is a non-monotonic stress-strain relation which -\nakin to classical friction - is independent of the shear rate. This relation\nsuffices to understand the below-threshold deformations of aging granular\nmedia, and its solid-to-liquid transition. Our results also elucidate the\n(flow) history dependence of the mechanical properties, and the sensitivity to\ninitial preparation of granular media."
    },
    {
        "anchor": "Translational and reorientational dynamics in carboxylic acid-based deep\n  eutectic solvents: The glass formation and the dipolar reorientational motions in deep eutectic\nsolvents (DESs) are frequently overlooked, despite their crucial role in\ndefining the room-temperature physiochemical properties. To understand the\neffects of these dynamics on the ionic conductivity and their relation to the\nmechanical properties of the DES, we conducted broadband dielectric and\nrheological spectroscopy over a wide temperature range on three\nwell-established carboxylic-acid-based natural DESs: oxaline, maline, and the\neutectic mixture of choline chloride with phenylacetic acid (phenylaceline). In\nall three DESs, we observe signs of glassy freezing in the temperature\ndependence of their dipolar reorientational and structural dynamics, as well as\nvarying degrees of motional decoupling between the different observed dynamics:\nMaline and oxaline display a breaking of the Walden rule near the\nglass-transition temperature, while the relation between the dc conductivity\nand dipolar relaxation time in both maline and phenylaceline is best described\nby a power law. The glass-forming properties of the investigated systems not\nonly govern the orientational dipolar motions and rheological properties, which\nare of interest from a fundamental point of view, but they also affect the dc\nconductivity, even at room temperature, which is of high technical relevance.",
        "positive": "Superadiabatic forces in the dynamics of the one-dimensional Gaussian\n  core model: Using Brownian dynamics computer simulations we investigate the dynamics of\nthe one-body density and one-body current in a one-dimensional system of\nparticles that interact with a repulsive Gaussian pair potential. We\nsystematically split the internal force distribution into an adiabatic part,\nwhich originates from the equilibrium free energy, and a superadiabatic\ncontribution, which is neglected in dynamical density functional theory. We\nfind a strong dependence of the magnitude and phase of the superadiabatic force\ndistribution on the initial state of the system. While the magnitude of the\nsuperadiabatic force is small if the system evolves from an equilibrium state\ninside of a parabolic external potential, it is large for particles with\nequidistant initial separations at high temperature. We analyze these findings\nin the light of the known mean-field behavior of Gaussian core particles and\ndiscuss a multi-occupancy mechanism which generates superadiabatic forces that\nare out of phase with respect to the adiabatic force."
    },
    {
        "anchor": "Configurational stability of a crack propagating in a material with\n  mode-dependent fracture energy -- Part II: Drift of fracture facets in\n  mixed-mode I+II+III: In earlier papers (Leblond et.al., 2011, 2019), we presented linear stability\nanalyses of the coplanar propagation of a crack loaded in mixed-mode I+III,\nbased on a \"double'' propagation criterion combining Griffith (1920)'s\nenergetic condition and Goldstein and Salganik (1974)'s principle of local\nsymmetry. The difference between the two papers was that in the more recent\none, the local value of the critical energy-release-rate was no longer\nconsidered as a constant, but heuristically allowed to depend upon the ratio of\nthe local mode III to mode I stress intensity factors. This led to a much\nimproved, qualitatively acceptable agreement of theory and experiments, for the\n\"threshold'' value of the ratio of the unperturbed mode III to mode I stress\nintensity factors, above which coplanar propagation becomes unstable. In this\npaper, the analysis is extended to the case where a small additional mode II\nloading component is present in the initially planar configuration of the\ncrack, generating a small, general kink of this crack from the moment it is\napplied. The main new effect resulting from presence of such a loading\ncomponent is that the instability modes present above the threshold must drift\nalong the crack front during its propagation. This prediction may be useful for\nfuture theoretical interpretations of a number of experiments where such a\ndrifting motion was indeed observed.",
        "positive": "Swimming to Stability: Structural and Dynamical Control via Active\n  Doping: External fields can decidedly alter the free energy landscape of soft\nmaterials and can be exploited as a powerful tool for the assembly of targeted\nnanostructures and colloidal materials. Here, we use computer simulations to\ndemonstrate that nonequilibrium internal fields or forces -- forces that are\ngenerated by driven components within a system -- in the form of active\nparticles can precisely modulate the dynamical free energy landscape of a model\nsoft material, a colloidal gel. Embedding a small fraction of active particles\nwithin a gel can provide a unique pathway for the dynamically frustrated\nnetwork to circumvent the kinetic barriers associated with reaching a lower\nfree energy state through thermal fluctuations alone. Moreover, by carefully\ntuning the active particle properties (the propulsive swim force and\npersistence length) in comparison to those of the gel, the active particles may\ninduce depletion-like forces between the constituent particles of the gel\ndespite there being no geometric size asymmetry between the particles. These\nresulting forces can rapidly push the system toward disparate regions of phase\nspace. Intriguingly, the state of the material can be altered by tuning\nmacroscopic transport properties such as the solvent viscosity. Our findings\nhighlight the potential wide-ranging structural and kinetic control facilitated\nby varying the dynamical properties of a remarkably small fraction of driven\nparticles embedded in a host material."
    },
    {
        "anchor": "Stress correlations in near-crystalline packings: We derive exact results for stress correlations in near-crystalline systems\nin two and three dimensions. We study energy minimized configurations of\nparticles interacting through Harmonic as well as Lennard-Jones potentials, for\nvarying degrees of microscopic disorder and quenched forces on grains. Our\nfindings demonstrate that the macroscopic elastic properties of such\nnear-crystalline packings remain unchanged within a certain disorder threshold,\nyet they can be influenced by various factors, including packing density,\npressure, and the strength of inter-particle interactions. We show that the\nstress correlations in such systems display anisotropic behavior at large\nlengthscales and are significantly influenced by the pre-stress of the system.\nThe anisotropic nature of these correlations remains unaffected as we increase\nthe strength of the disorder. Additionally, we derive the large lengthscale\nbehavior for the change in the local stress components that shows a $1/r^d$\nradial decay for the case of particle size disorder and a $1/r^{d-1}$ behavior\nfor quenched forces introduced into a crystalline network. Finally, we verify\nour theoretical results numerically using energy-minimised static particle\nconfigurations.",
        "positive": "Diffusion of liquid domains in lipid bilayer membranes: We report diffusion coeffcients of micron-scale liquid domains in giant\nunilamellar vesicles of phospholipids and cholesterol. The trajectory of each\ndomain is tracked, and the mean square displacement grows linearly in time as\nexpected for Brownian motion. We study domain dffusion as a function of\ncomposition and temperature, and measure how diffusion depends on domain size.\nWe find mechanisms of domain diffusion which are consistent with\nmembrane-dominated drag in viscous Lo phases [P.G. Saffman and M. Delbruck,\nPNAS 72, 3111 (1975)], and bulk-dominated drag for less viscous L$_\\alpha$\nphases [B.D.Hughes et al., J. Fluid Mech. 110, 349 (1981)]. Where applicable,\nwe obtain the membrane viscosity and report activation energies of diffusion."
    },
    {
        "anchor": "Can random pinning change the melting scenario of two-dimensional\n  core-softened potential system?: In experiments the two-dimensional systems are realized mainly on solid\nsubstrates which introduce quenched disorder due to some inherent defects. The\ndefects of substrates influence the melting scenario of the systems and have to\nbe taken into account in the interpretation of the experimental results. We\npresent the results of the molecular dynamics simulations of the two\ndimensional system with the core-softened potential in which a small fraction\nof the particles is pinned, inducing quenched disorder.The potentials of this\ntype are widely used for the qualitative description of the systems with the\nwater-like anomalies. In our previous publications it was shown that the system\ndemonstrates an anomalous melting scenario: at low densities the system melts\nthrough two continuous transition in accordance with the\nKosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory with the intermediate\nhexatic phase, while at high densities the conventional first order melting\ntransition takes place. We find that the well-known disorder-induced widening\nof the hexatic phase occurs at low densities, while at high density part of the\nphase diagram random pinning transforms the first-order melting into two\ntransitions: the continuous KTHNY-like solid-hexatic transition and first-order\nhexatic-isotropic liquid transition.",
        "positive": "The Ultrasensitivity of Living Polymers: Synthetic and biological living polymers are self-assembling chains whose\nchain length distributions (CLDs) are dynamic. We show these dynamics are\nultrasensitive: even a small perturbation (e.g. temperature jump) non-linearly\ndistorts the CLD, eliminating or massively augmenting short chains. The origin\nis fast relaxation of mass variables (mean chain length, monomer concentration)\nwhich perturbs CLD shape variables before these can relax via slow chain growth\nrate fluctuations. Viscosity relaxation predictions agree with experiments on\nthe best-studied synthetic system, alpha-methylstyrene."
    },
    {
        "anchor": "The \"isothermal\" compressibility of active matter: We demonstrate that the mechanically-defined \"isothermal\" compressibility\nbehaves as a thermodynamic-like response function for suspensions of active\nBrownian particles. The compressibility computed from the active pressure - a\ncombination of the collision and unique swim pressures - is capable of\npredicting the critical point for motility induced phase separation, as\nexpected from the mechanical stability criterion. We relate this mechanical\ndefinition to the static structure factor via an active form of the\nthermodynamic compressibility equation and find the two to be equivalent, as\nwould be the case for equilibrium systems. This equivalence indicates that\ncompressibility behaves like a thermodynamic response function, even when\nactivity is large. Finally, we discuss the importance of the phase interface\nwhen defining an active chemical potential. Previous definitions of the active\nchemical potential are shown to be accurate above the critical point but\nbreakdown in the coexistence region. Inclusion of the swim pressure in the\nmechanical compressibility definition suggests that the interface is essential\nfor determining phase behavior.",
        "positive": "Effective equilibrium states in the colored-noise model for active\n  matter I. Pairwise forces in the Fox and unified colored noise approximations: The equations of motion of active systems can be modeled in terms of\nOrnstein-Uhlenbeck processes (OUPs) with appropriate correlators. For further\ntheoretical studies, these should be approximated to yield a Markovian picture\nfor the dynamics and a simplified steady-state condition. We perform a\ncomparative study of the Unified Colored Noise Approximation (UCNA) and the\napproximation scheme by Fox recently employed within this context. We review\nthe approximations necessary to define effective interaction potentials in the\nlow-density limit and study the conditions for which these represent the\nbehavior observed in two-body simulations for the OUPs model and Active\nBrownian particles. The demonstrated limitations of the theory for potentials\nwith a negative slope or curvature can be qualitatively corrected by a new\nempirical modification. In general, we find that in the presence of\ntranslational white noise the Fox approach is more accurate. Finally, we\nexamine an alternative way to define a force-balance condition in the limit of\nsmall activity."
    },
    {
        "anchor": "Topological defects and the short-distance behavior of the structure\n  factor in nematic liquid crystals: The scattering of light at large wave-vector magnitudes k in nematic systems\ncontaining topological defects is investigated theoretically. At large k the\nstructure factor S(k) is dominated by power-law contributions originating from\nsingular order-parameter variations associated with topological defects and\nfrom transverse thermal fluctuations of the nematic director. These defects\n(nematic disclinations and hedgehogs) lead to contributions of the form rho A\nk^{-xi} (``the Porod tail''), where rho is the number density of a given type\nof defect, A is a dimensionless Porod amplitude, and xi is an integer-valued\nPorod exponent. The Porod amplitudes and exponents are calculated for all types\nof topologically stable defects occurring in uniaxial and biaxial nematics in\ntwo or three spatial dimensions. The range of wave-vectors in which the\ncontributions to the scattering intensity due to defects dominate the\ncontribution due to thermal fluctuations is estimated, and it is concluded that\nfor experimentally accessible defect densities the range of observability of\nthe Porod tail extends over one to three decades in scattering wave-vector\nmagnitude k. Available experimental results on phase ordering in uniaxial\nnematics are analyzed, and applications of our results are suggested for\nlight-scattering studies of other nematic systems containing numerous defects.",
        "positive": "Solution of the spherically symmetric linear thermoviscoelastic problem\n  in the inertia-free limit: The coupling between mechanical and thermal properties due to thermal\nexpansion complicates the problem of measuring frequency-dependent\nthermoviscoelastic properties, in particular for highly viscous liquids. A\nsimplification arises if there is spherical symmetry where - as detailed in the\npresent paper - the thermoviscoelastic problem may be solved analytically in\nthe inertia-free limit, i.e., the limit where the sample is much smaller than\nthe wavelength of sound waves at the frequencies of interest. As for the\none-dimensional thermoviscoelastic problem [Christensen et al., Phys. Rev. E\n75, 041502 (2007)], the solution is conveniently formulated in terms of the\nso-called transfer matrix, which directly links to the boundary conditions that\ncan be experimentally controlled. Once the transfer matrix has been calculated,\nit is fairly easy to deduce the equations describing various experimentally\nrelevant special cases (boundary conditions that are adiabatic, isothermal,\nisochoric, etc.). In most situations the relevant frequency-dependent specific\nheat is the longitudinal specific heat, a quantity that is in between the\nisochoric and isobaric frequency-dependent specific heats."
    },
    {
        "anchor": "A planar force-constant model for phonons in wurtzite GaN and AlN:\n  Application to hexagonal GaN/AlN superlattices: A planar force-constant model is developed for longitudinal phonons of\nwurtzite GaN and AlN propagating along the [0001] direction. The proposed model\nis then applied to the study of the phonon modes in hexagonal GaN/AlN\nsuperlattices in the longitudinal polarization. The confinement of the\nsuperlattice phonon mode is discussed.",
        "positive": "Particle pinning as a method to manipulate marginal stability: We study the critical behavior of low-frequency vibrations of packings with\npinned particles near the jamming point. Soft modes form a plateau in the\ndensity of states and its frequency is controlled by the contact number as the\nordinary jamming transition. The spatial structure of these modes is not\nlargely affected by pins. Below the plateau, the non-Debye scaling predicted by\nmean-field theories and quasi-localized modes breaks down depending on the\npinning procedures. We comprehensively explain these behaviors by the impact of\npinning operations on the marginal stability of the packings."
    },
    {
        "anchor": "The hydrophobic effect characterises the thermodynamic signature of\n  amyloid fibril growth: Many proteins have the potential to aggregate into amyloid fibrils, which are\nassociated with a wide range of human disorders including Alzheimer's and\nParkinson's disease. In contrast to that of folded proteins, the thermodynamic\nstability of amyloid fibrils is not well understood: specifically the balance\nbetween entropic and enthalpic terms, including the chain entropy and the\nhydrophobic effect, are poorly characterised. Using simulations of a\ncoarse-grained protein model we delineate the enthalpic and entropic\ncontributions dominating amyloid fibril elongation, predicting a characteristic\ntemperature-dependent enthalpic signature. We confirm this thermodynamic\nsignature by performing calorimetric experiments and a meta-analysis over\npublished data. From these results, we can also elucidate the necessary\nconditions to observe cold denaturation of amyloid fibrils. Overall, we show\nthat amyloid fibril elongation is associated with a negative heat capacity, the\nmagnitude of which correlates closely with the hydrophobic surface area that is\nburied upon fibril formation, highlighting the importance of hydrophobicity for\nfibril stability.",
        "positive": "Electromechanical properties of ferroelectric polymers: Finsler geometry\n  modeling and a Monte Carlo study: Polyvinylidene difluoride (PVDF) is a ferroelectric polymer characterized by\nnegative strain along the direction of the applied electric field. However, the\nelectromechanical response mechanism of PVDF remains unclear due to the\ncomplexity of the hierarchical structure across the length scales. As described\nin this letter, we employ the Finsler geometry model as a new solution to the\naforementioned problem and demonstrate that the deformations observed through\nMonte Carlo simulations on 3D tetrahedral lattices are nearly identical to\nthose of real PVDF. Specifically, the simulated mechanical deformation and\npolarization are similar to those observed experimentally."
    },
    {
        "anchor": "Extension of the primitive model by hydration shells and its impact on\n  the reversible heat production during the buildup of the electric double\n  layer: Recently the reversible heat production during the electric double layer\n(EDL) buildup in a sodium chloride solution was measured experimentally\n[Janssen et al., Phys. Rev. Lett. 119, 166002 (2017)] and matched with\ntheoretical predictions from density functional theory and molecular dynamics\nsimulations [Glatzel et al., J. Chem. Phys. 154, 064901 (2021)]. In the latter,\nit was found that steric interactions of ions with the electrode's walls, which\nresult in the so-called Stern layer, are sufficient to explain the experimental\nresults. As only symmetric ion sizes in a restricted primitive model were\nexamined, it is instructive to investigate systems of unequal ion sizes that\nlead to modified Stern layers. In this work, we explore the impact of ion\nasymmetry on the reversible heat production for each electrode separately. In\nthis context, we further study an extension of the primitive model where\nhydration shells of ions can evade in the vicinity of electrode's walls. We\nfind a strong dependence on system parameters such as the particle sizes and\nthe total volume taken by particles. Here, we even found situations where one\nelectrode was heated and the other electrode was cooled at the same time during\ncharging, while, in sum, both electrodes together behaved very similarly to the\nalready mentioned experimental results. Thus, heat production should also be\nmeasured in experiments for each electrode separately. By this, the importance\nof certain ingredients that we proposed to model electrolytes could be\nconfirmed or ruled out experimentally, finally leading to a deeper\nunderstanding of the physics of EDLs.",
        "positive": "Critical phase behavior in multi-component fluid mixtures: Complete\n  scaling analysis: We analyze the critical gas-liquid phase behavior of arbitrary fluid mixtures\nin their coexistence region. We focus on the setting relevant for polydisperse\ncolloids, where the overall density and composition of the system are being\ncontrolled, in addition to temperature. Our analysis uses the complete scaling\nformalism and thus includes pressure mixing effects in the mapping from\nthermodynamic fields to the effective fields of 3D Ising criticality. Because\nof fractionation, where mixture components are distributed unevenly across\ncoexisting phases, the critical behavior is remarkably rich. We give scaling\nlaws for a number of important loci in the phase diagram. These include the\ncloud and shadow curves, which characterise the onset of phase coexistence, a\nmore general set of curves defined by fixing the fractional volumes of the\ncoexisting phases to arbitrary values, and conventional coexistence curves of\nthe densities of coexisting phases for fixed overall density. We identify\nsuitable observables (distinct from the Yang-Yang anomalies discussed in the\nliterature) for detecting pressure mixing effects. Our analytical predictions\nare checked against numerics using a set of mapping parameters fitted to\nsimulation data for a polydisperse Lennard-Jones fluid, allowing us to\nhighlight crossovers where pressure mixing becomes relevant close to the\ncritical point."
    },
    {
        "anchor": "Microscopic Structural Relaxation in a Sheared Supercooled Colloidal\n  Liquid: The rheology of dense amorphous materials under large shear strain is not\nfully understood, partly due to the difficulty of directly viewing the\nmicroscopic details of such materials. We use a colloidal suspension to\nsimulate amorphous materials, and study the shear-induced structural relaxation\nwith fast confocal microscopy. We quantify the plastic rearrangements of the\nparticles in several ways. Each of these measures of plasticity reveals\nspatially heterogeneous dynamics, with localized regions where many particles\nare strongly rearranging by these measures. We examine the shapes of these\nregions and find them to be essentially isotropic, with no alignment in any\nparticular direction. Furthermore, individual particles are equally likely to\nmove in any direction, other than the overall bias imposed by the strain.",
        "positive": "Ionic effects in self-propelled Pt-coated Janus swimmers: Colloidal particles partially coated with platinum and dispersed in H2O2\nsolution are often used as model self-propelled colloids. Most current data\nsuggest that neutral self-diffusiophoresis propels these particles. However,\nseveral studies have shown strong ionic effects in this and related systems,\nsuch as a reduction of propulsion speed by salt. We investigate these ionic\neffects in Pt-coated polystyrene colloids, and find here that the direction of\npropulsion can be reversed by addition of an ionic surfactant, and that\nalthough adding pH neutral salts reduces the propulsion speed, adding the\nstrong base NaOH has little effect. We use these data, as well as measured\nreaction rates, to argue against propulsion by either neutral or ionic\nself-diffusiophoresis, and suggest instead that the particle's propulsion\nmechanism may in fact bear close resemblance to that operative in bimetallic\nswimmers."
    },
    {
        "anchor": "One-Loop Fluctuation Entropy of Charge Inversion in DNA: Experiments have revealed correlation-driven behavior of DNA in charged\nsolutions, including charge inversion and condensation. This paper presents\ncalculations of a lattice-gas model of charge inversion for the adsorption of\ncharged dimers on DNA. Each adsorption site is assumed to have either a vacancy\nor a positively-charged dimer attached with the dimer oriented either parallel\nor perpendicular to the double helix DNA chain. The entropy and charge\ndistributions of these three species are calculated including the lowest order\nfluctuation corrections to mean-field theory. We find that the inclusion of the\nfluctuation terms has a significant effect on the entropy, primarily in the\nregime where the dimers are repelled from the DNA molecule and compete with the\nchemical potential in solution.",
        "positive": "Accurate description of bulk and interfacial properties in\n  colloid-polymer mixtures: Large-scale Monte Carlo simulations of a phase-separating colloid-polymer\nmixture are performed and compared to recent experiments. The approach is based\non effective interaction potentials in which the central monomers of\nself-avoiding polymer chains are used as effective coordinates. By\nincorporating polymer nonideality together with soft colloid-polymer repulsion,\nthe predicted binodal is in excellent agreement with recent experiments. In\naddition, the interfacial tension as well as the capillary length are in\nquantitative agreement with experimental results obtained at a number of points\nin the phase-coexistence region, without the use of any fit parameters"
    },
    {
        "anchor": "Elastic theory of low-dimensional continua and its applications in bio-\n  and nano-structures: This review presents the elastic theory of low-dimensional (one- and\ntwo-dimensional) continua and its applications in bio- and nano-structures.\nFirst, the curve and surface theory, as the geometric representation of the\nlow-dimensional continua, is briefly described through Cartan moving frame\nmethod. The elastic theory of Kirchhoff rod, Helfrich rod, bending-soften rod,\nfluid membrane, and solid shell is revisited. Secondly, the application and\navailability of the elastic theory of low-dimensional continua in\nbio-structures, including short DNA rings, lipid membranes, and cell membranes,\nare discussed. The kink stability of short DNA rings is addressed by using the\ntheory of Kirchhoff rod, Helfrich rod, and bending-soften rod. The lipid\nmembranes obey the theory of fluid membrane. A cell membrane is simplified as a\ncomposite shell of lipid bilayer and membrane skeleton, which is a little\nsimilar to the solid shell. It is found that the membrane skeleton enhances\nhighly the mechanical stability of cell membranes. Thirdly, the application and\navailability of the elastic theory of low-dimensional continua in\nnano-structures, including graphene and carbon nanotubes, are discussed. A\nrevised Lenosky lattice model is proposed based on the local density\napproximation. Its continuum form up to the second order terms of curvatures\nand strains is the same as the free energy of 2D solid shells. Several typical\nmechanical properties of carbon nanotubes are revisited and investigated based\non this continuum form. It is possible to avoid introducing the controversial\nconcepts, the Young's modulus and thickness of graphene and single-walled\ncarbon nanotubes, with this continuum form.",
        "positive": "A solvable senescence model showing a mortality plateau: We present some analytic results for the steady states of the Penna model of\nsen escence, generalised to allow genetically identical individuals to die at\ndiffer ent ages via an arbitrary survival function. Modelling this with a Fermi\nfunctio n (of modest width) we obtain a clear mortality plateau late in life:\nsomething that has so far eluded explanation within such mutation accumulation\nmodels. This suggests that factors causing variable mortality withi n\ngenetically identical subpopulations, which include environmental effects, may\nbe essential to understanding the mortality plateau seen in many real species."
    },
    {
        "anchor": "Capillary-driven binding of thin triangular prisms at fluid interfaces: We observe capillary-driven binding between thin, equilateral triangular\nprisms at a flat air-water interface. The edge length of the equilateral\ntriangle face is 120 $\\mu m$, and the thickness of the prism is varied between\n2 and 20 $\\mu m$. For thickness to length (T/L) ratios of 1/10 or less, pairs\nof triangles preferentially bind in either a tip-to-tip or tip-to-midpoint edge\nconfigurations; for pairs of particles of thickness T/L = 1/5, the tip of one\ntriangle binds to any position along the other triangle's edge. The distinct\nbinding configurations for small T/L ratios result from physical bowing of the\nprisms, a property that arises during their fabrication. When bowed prisms are\nplaced at the air-water interface, two distinct polarity states arise: prisms\neither sit with their center of mass above or below the interface. The\ninterface pins to the edge of the prism's concave face, resulting in an\ninterface profile that is similar to that of a capillary hexapole, but with\nimportant deviations close to the particle that enable directed binding. We\npresent corresponding theoretical and numerical analysis of the capillary\ninteractions between these prisms and show how particle bowing and contact-line\npinning yield a capillary hexapole-like interaction that results in the two\nsets of distinct, highly-directional binding events. Prisms of all T/L ratios\nself-assemble into space-spanning open networks; the results suggest design\nparameters for the fabrication of building blocks of ordered open structures\nsuch as the Kagome lattice.",
        "positive": "Simplified Onsager theory for isotropic-nematic phase equilibria of\n  length polydisperse hard rods: Polydispersity is believed to have important effects on the formation of\nliquid crystal phases in suspensions of rod-like particles. To understand such\neffects, we analyse the phase behaviour of thin hard rods with length\npolydispersity. Our treatment is based on a simplified Onsager theory, obtained\nby truncating the series expansion of the angular dependence of the excluded\nvolume. We describe the model and give the full phase equilibrium equations;\nthese are then solved numerically using the moment free energy method which\nreduces the problem from one with an infinite number of conserved densities to\none with a finite number of effective densities that are moments of the full\ndensity distribution. The method yields exactly the onset of nematic ordering.\nBeyond this, results are approximate but we show that they can be made\nessentially arbitrarily precise by adding adaptively chosen extra moments,\nwhile still avoiding the numerical complications of a direct solution of the\nfull phase equilibrium conditions.\n  We investigate in detail the phase behaviour of systems with three different\nlength distributions: a (unimodal) Schulz distribution, a bidisperse\ndistribution and a bimodal mixture of two Schulz distributions which\ninterpolates between these two cases. A three-phase isotropic-nematic-nematic\ncoexistence region is shown to exist for the bimodal and bidisperse length\ndistributions if the ratio of long and short rod lengths is sufficiently large,\nbut not for the unimodal one. We systematically explore the topology of the\nphase diagram as a function of the width of the length distribution and of the\nrod length ratio in the bidisperse and bimodal cases."
    },
    {
        "anchor": "Effect of pulse width on the dynamics of a deflated vesicle in unipolar\n  and bipolar pulsed electric fields: Giant unilamellar vesicles subjected to pulsed direct-current (pulsed-DC)\nfields are promising biomimetic systems to investigate the electroporation of\ncells. In strong electric fields, vesicles undergo significant deformation,\nwhich strongly alters the transmembrane potential, consequently the\nelectroporation. Previous theoretical studies investigated the\nelectrodeformation of vesicles in DC fields (which are not pulsed). In this\nwork, we computationally investigate the deformation of a deflated vesicle\nunder unipolar, bipolar, and two-step unipolar pulses and show sensitive\ndependence of intermediate shapes on type of pulse and the pulse width.\nStarting with the stress-free initial shape of a deflated vesicle, which is\nsimilar to a prolate spheroid, the analysis is presented for the cases with\nhigher and lower conductivities of the inner fluid medium relative to the outer\nfluid medium. For the ratio of inner to outer fluid conductivity,\n$\\sigma_\\mathrm{r}$ = 10, the shape always remains prolate, including when the\nfield is turned off. For $\\sigma_\\mathrm{r} = 0.1$, several complex dynamics\nare observed, such as the prolate-to-oblate (PO), prolate-to-oblate-to-prolate\n(POP) shape transitions in time depending upon the strength of the field and\nthe pulse properties. In this case, on turning off the field, a metastable\noblate equilibrium shape is seen, that seems to be a characteristics of a\ndeflated vesicle leading to POPO transitions. When a two-step unipolar pulse (a\ncombination of a strong and a weak subpulse) is applied, a vesicle can reach an\noblate or a prolate final shape depending upon the relative durations of the\ntwo subpulses.",
        "positive": "Finite-size scaling at the edge of disorder in a time-delay Vicsek model: Living many-body systems often exhibit scale-free collective behavior\nreminiscent of thermal critical phenomena. But their mutual interactions are\ninevitably retarded due to information processing and delayed actuation. We\nnumerically investigate the consequences for the finite-size scaling in the\nVicsek model of motile active matter. A growing delay time initially\nfacilitates but ultimately impedes collective ordering and turns the dynamical\nscaling from diffusive to ballistic. It provides an alternative explanation of\nswarm traits previously attributed to inertia."
    },
    {
        "anchor": "Bi-defects of Nematic Surfactant Bilayers: We consider the effects of the coupling between the orientational order of\nthe two monolayers in flat nematic bilayers. We show that the presence of a\ntopological defect on one bilayer generates a nontrivial orientational texture\non both monolayers. Therefore, one cannot consider isolated defects on one\nmonolayer, but rather associated pairs of defects on either monolayer, which we\ncall bi-defects. Bi-defects generally produce walls, such that the textures of\nthe two monolayers are identical outside the walls, and different in their\ninterior. We suggest some experimental conditions in which these structures\ncould be observed.",
        "positive": "Computational Study of Trimer Self-Assembly and Fluid Phase Behavior: The fluid phase diagram of trimer particles composed of one central\nattractive bead and two repulsive beads was determined as a function of simple\ngeometric parameters using flat-histogram Monte Carlo methods. A variety of\nself-assembled structures were obtained including spherical micelle-like\nclusters, elongated clusters and densely packed cylinders, depending on both\nthe state conditions and shape of the trimer. Advanced simulation techniques\nwere employed to determine transitions between self-assembled structures and\nmacro- scopic phases using thermodynamic and structural definitions. Simple\nchanges in particle geometry yield dramatic changes in phase behavior, ranging\nfrom macroscopic fluid phase separation to molecular-scale self- assembly. In\nspecial cases, both self-assembled, elongated clusters and bulk fluid phase\nseparation occur simultaneously. Our work suggests that tuning particle shape\nand interactions can yield superstructures with controlled architecture."
    },
    {
        "anchor": "Compression of a confined semiflexible polymer under direct and\n  oscillating fields: The folding transition of biopolymers from the coil to compact structures has\nattracted wide research interest in the past and is well studied in polymer\nphysics. Recent seminal works on DNA in confined devices have shown that these\nlong biopolymers tend to collapse under an external field, contrary to the\npreviously reported stretching. These long folded structures have a tendency to\nform knots that has profound implications in gene regulation and various other\nbiological functions. These knots have been mechanically induced via optical\ntweezers, nanochannel confinement, etc., until recently, where uniform field\ndriven compression lead to self entanglement of DNA. In this work, we capture\nthe compression of a confined semiflexible polymer under direct and oscillating\nfields, using a coarse-grained computer simulation model in the presence of\nlong-range hydrodynamics. Within this framework, we show that subjected to\ndirect field, chains in stronger confinements exhibit substantial compaction,\ncontrary to the one in moderate confinements or bulk, where such compaction is\nabsent. Interestingly, an alternating field within an optimum frequency can\neffectuate this compression even in moderate or no confinement. Additionally,\nwe show that the bending rigidity has a profound influence on the chains\nfolding favourability under direct and alternating fields. This field induced\ncollapse is a quintessential hydrodynamic phenomenon, resulting in intertwined\nknotted structures, even for shorter chains, unlike DNA knotting experiments,\nwhere it happens exclusively for longer chains.",
        "positive": "Geometry-dependent constitutive law for granular slow frictional drag: Frictional constitutive law for very slow vertical withdrawing of a thin rod\nfrom a granular bed is experimentally studied. Using a very precise creep\nmeter, geometry-dependent granular frictional constitutive law is particularly\nexamined. In some previous works, a dimensionless number\n$I=\\dot{\\gamma}D_g/\\sqrt{p/\\rho_g}$ has been used to characterize granular\nfrictional constitutive laws, where $\\dot{\\gamma}$, $D_g$, $p$, and $\\rho_g$\nare the shear strain rate, grain diameter, confining pressure, and bulk density\nof granular bed, respectively. It has been considered that granular frictional\nconstitutive law expressed by $I$ is universal (almost geometry-independent) in\ndense flow regime. In this study, however, we find that the geometry of the\nsystem is much more crucial to characterize granular friction in a very slow\nwithdrawing regime. Specifically, the ratio between rod and grain diameters\nmust be an essential parameter to describe the granular frictional constitutive\nlaw. Physical meaning of the geometry-dependent constitutive law is discussed\non the basis of grains-contact-number dependence of granular behavior."
    },
    {
        "anchor": "Single-Step Synthesis of Shape-Controlled Polymeric Particles using\n  Initiated Chemical Vapor Deposition in Liquid Crystals: The ability to synthesize shape-controlled polymer particles will benefit a\nwide range of applications including targeted drug delivery and metamaterials\nwith reconfigurable structures, but existing synthesis approaches are commonly\nmultistep and limited to a narrow size/shape range. Using a novel single-step\nsynthesis technique, a variety of shapes including nanospheres, hemispherical\nmicro-domes, orientation-controlled microgels, microspheres, spheroids, and\nmicro-discs were obtained. The shape-controlled particles were synthesized by\npolymerizing divinylbenzene (DVB) via initiated chemical vapor deposition\n(iCVD) in nematic liquid crystals (LC). iCVD continuously and precisely\ndelivered vapor-phase reactants, thus avoiding disruption of the LC structure,\na critical limitation in past LC-templated polymerization. That shape\ncontrollability was further enabled by leveraging LC as a real-time display of\nthe polymerization conditions and progression, using a custom in-situ\nlong-focal range microscope. Detailed image analysis unraveled key mechanisms\nin polymer synthesis in LC. Poor solubilization by nematic LC led to the\nformation of pDVB nanospheres, distinct from microspheres obtained in isotropic\nsolvents. The nanospheres precipitated to the LC-solid interface and further\naggregated into microgel clusters with controlled orientation that was guided\nby the LC molecular alignment. On further polymerization, microgel clusters\nphase separated to form microspheres, spheroids, and unique disc-shaped\nparticles.",
        "positive": "Electrophoretic Properties of Highly Charged Colloids: A Hybrid MD/LB\n  Simulation Study: Using computer simulations, the electrophoretic motion of a positively\ncharged colloid (macroion) in an electrolyte solution is studied in the\nframework of the primitive model. Hydrodynamic interactions are fully taken\ninto account by applying a hybrid simulation scheme, where the charged ions\n(i.e. macroion and electrolyte), propagated via molecular dynamics (MD), are\ncoupled to a Lattice Boltzmann (LB) fluid. In a recent experiment it was shown\nthat, for multivalent salt ions, the mobility $\\mu$ initially increases with\ncharge density $\\sigma$, reaches a maximum and then decreases with further\nincrease of $\\sigma$. The aim of the present work is to elucidate the behaviour\nof $\\mu$ at high values of $\\sigma$. Even for the case of monovalent microions,\nwe find a decrease of $\\mu$ with $\\sigma$. A dynamic Stern layer is defined\nthat includes all the counterions that move with the macroion while subject to\nan external electrical field. The number of counterions in the Stern layer,\n$q_0$, is a crucial parameter for the behavior of $\\mu$ at high values of\n$\\sigma$. In this case, the mobility $\\mu$ depends primarily on the ratio\n$q_0/Q$ (with $Q$ the valency of the macroion). The previous contention that\nthe increase in the distortion of the electric double layer (EDL) with\nincreasing $\\sigma$ leads to the lowering of $\\mu$ does not hold for high\n$\\sigma$. In fact, we show that the deformation of the EDL decreases with\nincrease of $\\sigma$. The role of hydrodynamic interactions is inferred from\ndirect comparisons to Langevin simulations where the coupling to the LB fluid\nis switched off. Moreover, systems with divalent counterions are considered. In\nthis case, at high values of $\\sigma$ the phenomenon of charge inversion is\nfound."
    },
    {
        "anchor": "Fluid-membrane tethers: minimal surfaces and elastic boundary layers: Thin cylindrical tethers are common lipid bilayer membrane structures,\narising in situations ranging from micromanipulation experiments on artificial\nvesicles to the dynamic structure of the Golgi apparatus. We study the shape\nand formation of a tether in terms of the classical soap-film problem, which is\napplied to the case of a membrane disk under tension subject to a point force.\nA tether forms from the elastic boundary layer near the point of application of\nthe force, for sufficiently large displacement. Analytic results for various\naspects of the membrane shape are given.",
        "positive": "Triangular avalanches and uphill instabilities: Recent experiments show that an avalanche initiated from a point source\npropagates downwards by invading a triangular shaped region. The opening angle\nof this triangle appears to reach 180$^o$ for a critical inclination of the\npile, beyond which avalanches also propage upwards. We propose a simple\ninterpretation of these observations, based on an extension of a\nphenomenological model for surface flows."
    },
    {
        "anchor": "Elastic Instability Triggered Pattern Formation: Recent experiments have exploited elastic instabilities in membranes to\ncreate complex patterns. However, the rational design of such structures poses\nmany challenges, as they are products of nonlinear elastic behavior. We pose a\nsimple model for determining the orientational order of such patterns using\nonly linear elasticity theory which correctly predicts the outcomes of several\nexperiments. Each element of the pattern is modeled by a \"dislocation dipole\"\nlocated at a point on a lattice, which then interacts elastically with all\nother dipoles in the system. We explicitly consider a membrane with a square\nlattice of circular holes under uniform compression and examine the changes in\nmorphology as it is allowed to relax in a specified direction.",
        "positive": "Vibrational properties of two-dimensional dimer packings near the\n  jamming transition: Jammed particulate systems composed of various shapes of particles undergo\nthe jamming transition as they are compressed or decompressed. To date, sphere\npackings have been extensively studied in many previous works, where\nisostaticity at the transition and scaling laws with the pressure of various\nquantities, including the contact number and the vibrational density of states,\nhave been established. Additionally, much attention has been paid to\nnonspherical packings, and particularly recent work has made progress in\nunderstanding ellipsoidal packings. In the present work, we study the dimer\npackings in two dimensions, which have been much less understood than systems\nof spheres and ellipsoids. We first study the contact number of dimers near the\njamming transition. It turns out that packings of dimers have \"rotational\nrattlers\", each of which still has a free rotational motion. After correcting\nthis effect, we show that dimers become isostatic at the jamming, and the\nexcess contact number obeys the same critical law and finite size scaling law\nas those of spheres. We next study the vibrational properties of dimers near\nthe transition. We find that the vibrational density of states of dimers\nexhibits two characteristic plateaus that are separated by a peak. The\nhigh-frequency plateau is dominated by the translational degree of freedom,\nwhile the low-frequency plateau is dominated by the rotational degree of\nfreedom. We establish the critical scaling laws of the characteristic\nfrequencies of the plateaus and the peak near the transition. In addition, we\npresent detailed characterizations of the real space displacement fields of\nvibrational modes in the translational and rotational plateaus."
    },
    {
        "anchor": "How to quantify structural anomalies in fluids?: Some fluids are known to behave anomalously. The so-called structural anomaly\nwhich means that the fluid becomes less structures under isothermal compression\nis among the most frequently discussed ones. Several methods for quantifying\nthe degree of structural order are described in the literature and are used for\ncalculating the regions of structural anomalies. It is implied that all of the\nstructural order determinations yield qualitatively identical results. However,\nno explicit comparison was made. This paper presents such a comparison for the\nfirst time. the results of some definitions are shown to contradict the\nintuitive notion of a fluid. On the basis of this comparison we show that the\nstructural anomaly can be most reliably determined from the behavior of the\nexcess entropy.",
        "positive": "\"Twist-Controlled\" force amplification \\& Spinning tension transition in\n  yarn: Combining experiments and numerical simulations with a mechanical/statistical\nmodel of twisted yarns, we discuss the spinning transition between a\ncohesion-less assembly of fibers into a yarn. We show that this transition is\ncontinuous but very sharp due to a giant amplification of frictional forces\nwhich scales as $\\exp \\theta ^2$, where $\\theta$ is the twist angle. We\ndemonstrate that this transition is controlled solely by a non-dimensional\nnumber ${\\mathcal{H}}$ involving twist, friction coefficient, and geometric\nlengths. A critical value of this number ${\\mathcal{H}} \\simeq 30$ can be\nlinked to a locking of the fibers together as the tensile strength is reached.\nThis critical value imposes that yarns must be very slender structures with a\ngiven pitch. It also induces the existence of an optimal yarn radius.\nPredictions of our theory are successfully compared to yarns made from natural\ncotton fibers."
    },
    {
        "anchor": "Fluid leakage near the percolation threshold: Percolation is a concept widely used in many fields of research and refers to\nthe propagation of substances through porous media (e.g., coffee filtering), or\nthe behaviour of complex networks (e.g., spreading of diseases). Percolation\ntheory asserts that most percolative processes are universal, that is, the\nemergent powerlaws only depend on the general, statistical features of the\nmacroscopic system, but not on specific details of the random realisation. In\ncontrast, our computer simulations of the leakage through a seal---applying\ncommon assumptions of elasticity, contact mechanics, and fluid dynamics---show\nthat the critical behaviour (how the flow ceases near the sealing point) solely\ndepends on the microscopic details of the last constriction. It appears\nfundamentally impossible to accurately predict from statistical properties of\nthe surfaces alone how strongly we have to tighten a water tap to make it stop\ndripping and also how it starts dripping once we loosen it again.",
        "positive": "Dynamic and instability of submarine avalanches: We perform a laboratory-scale experiment of submarine avalanches on a rough\ninclined plane. A sediment layer is prepared and thereafter tilted up to an\nangle lower than the spontaneous avalanche angle. The sediment is scrapped\nuntil an avalanche is triggered. Based on the stability diagram of the sediment\nlayer, we investigate different structures for the avalanche front dynamics.\nFirst we see a straight front descending the slope, and then a transverse\ninstability occurs. Eventually, a fingering instability shows up similar to\nrivulets appearing for a viscous fluid flowing down an incline. The mechanisms\nleading to this new instability and the wavelength selection are discussed."
    },
    {
        "anchor": "Minimal Lattice Model of Lipid Membranes with Liquid-Ordered Domains: Mixtures of lipids and cholesterol are commonly used as model systems for\nstudying the formation of liquid-ordered ($L_o$) domains in heterogeneous\nbiological membranes. The simplest model system exhibiting coexistence between\n$L_o$ domains and a liquid-disordered ($L_d$) matrix is that of a binary\nmixture of saturated lipids like DPPC and cholesterol (Chol). DPPC/Chol\nmixtures have been investigated for decades both experimentally, theoretically,\nand recently also by means of atomistic simulations. Here, we present a minimal\nlattice model that captures the correct behavior of this mixture across\nmultiple scales. On the macroscopic scales, we present simulation results of\nmixtures of thousands of lipids and Chol molecules which show excellent\nagreement with the phase diagram of the system. The simulations are conducted\non timescales of hundreds of microseconds and show the morphologies and\ndynamics of the domains. On the molecular scales, the simulations reveal local\nstructures similar to those recently seen in atomistic simulations, including\nthe formation of gel-like nano-domains ($\\sim$ 1-10 nm) within larger Chol-rich\n$L_o$ domains ($\\sim$ 10-100 nm). The observed multi-scale behavior is related\nto the tendency of Chol to induce ordering of acyl chains on the one hand, and\ndisrupt their packing with each other, on the other hand.",
        "positive": "Towards artificial muscles: Solid state actuators (piezoelectric, ferroelectric, ...) deform under an\nexternal field, and have found many applications. They respond fast, but their\nmechanical deformations are very small. There is a need for soft actuators,\ngiving larger responses, but necessarily less fast. This paper describes the\nearly attempts by Katchalsky and others, and the problems which showed up\n-related to time constants, and, most importantly, to fatigue. Two current\nattempts are reviewed."
    },
    {
        "anchor": "Modelling of liquid internal energy and heat capacity over a wide\n  pressure-temperature range from first principles: Recently there have been significant theoretical advances in our\nunderstanding of liquids and dense supercritical fluids based on their ability\nto support high frequency transverse (shear) waves. Here, we have constructed a\nnew computer model using these recent theoretical findings (the phonon theory\nof liquid thermodynamics), to model liquid internal energy across a wide\npressure-temperature range. We have applied it to a number of real liquids in\nboth the subcritical regime and the supercritical regime, in which the liquid\nstate is demarcated by the Frenkel line. Our fitting to experimental data in a\nwide pressure-temperature range has allowed us to test the new theoretical\nmodel with hitherto unprecedented rigour. We have quantified the degree to\nwhich the prediction of internal energy and heat capacity is constrained by the\ndifferent input parameters: The liquid relaxation time (initially obtained from\nthe viscosity), the Debye wavenumber and the infinite-frequency shear modulus.\nThe model is successfully applied to output the internal energy and heat\ncapacity data for several different fluids (Ar, Ne, $N_2$, Kr) over a range of\ndensities and temperatures. We find that the predicted heat capacities are\nextremely sensitive to the values used for the liquid relaxation time. If these\nare calculated directly from the viscosity data then, in some cases, changes\nwithin the margins of experimental error in the viscosity data can cause the\nheat capacity to exhibit a completely different trend as a function of\ntemperature. Our code is computationally inexpensive, and it is available for\nother researchers to use.",
        "positive": "Inverse design of charged colloidal particle interactions for self\n  assembly into specified crystal structures: We study the inverse problem of tuning interaction parameters between charged\ncolloidal particles interacting with a hard-core repulsive Yukawa potential, so\nthat they assemble into specified crystal structures. Here, we target the\nbody-centered-cubic (bcc) structure which is only stable in a small region in\nthe phase diagram of charged colloids and is, therefore, challenging to find.\nIn order to achieve this goal, we use the statistical fluctuations in the bond\norientational order parameters to tune the interaction parameters for the bcc\nstructure, while initializing the system in the fluid phase, using the\nStatistical Physics-inspired Inverse Design (SP-ID) algorithm [1]. We also find\nthat this optimization algorithm correctly senses the fluid-solid phase\nboundaries for charged colloids. Finally, we repeat the procedure employing the\nCovariance Matrix Adaptation - Evolution Strategy (CMA-ES), a cutting edge\noptimization technique, and compare the relative efficacy of the two methods."
    },
    {
        "anchor": "Studies of reversible capsid shell growth: Results from molecular dynamics simulations of simple, structured particles\ncapable of self-assembling into polyhedral shells are described. The analysis\nfocuses on the growth histories of individual shells in the presence of an\nexplicit solvent and the nature of the events along their growth pathways; the\nresults provide further evidence of the importance of reversibility in the\nassembly process. The underlying goal of this approach is the modeling of virus\ncapsid growth, a phenomenon at the submicroscopic scale that, despite its\nimportance, is little understood.",
        "positive": "An Expression for the Granular Elastic Energy: Granular Solid Hydrodynamics (GSH) is a broad-ranged continual mechanical\ndescription of granular media capable of accounting for static stress\ndistributions, yield phenomena, propagation and damping of elastic waves, the\ncritical state, shear band, and fast dense flow. An important input of GSH is\nan expression for the elastic energy needed to deform the grains. The original\nexpression, though useful and simple, has some draw-backs. Therefore, a\nslightly more complicated expression is proposed here that eliminates three of\nthem: (1) The maximal angle at which an inclined layer of grains remains stable\nis increased from $26^\\circ$ to the more realistic value of $30^\\circ$.\n(2)Depending on direction and polarization, transverse elastic waves are known\nto propagate at slightly different velocities. The old expression neglects\nthese differences, the new one successfully reproduces them. (3) Most\nimportantly, the old expression contains only the Drucker-Prager yield surface.\nThe new one contains in addition those named after Coulomb, Lade-Duncan and\nMatsuoka-Nakai -- realizing each, and interpolating between them, by shifting a\nsingle scalar parameter."
    },
    {
        "anchor": "Desiccation and Relaxation Regimes in Fracture of Drying Clay Films: A study of crack patterns in laponite films of different thickness is\npresented. Two cracking regimes are observed. The earlier with a higher rate of\ndesiccation and shrinking has predominantly four-fold vertices in the crack\nnetwork, while the later regime has less volume shrinking and forms mainly\nthree-fold vertices. The pattern shows a self-similarity under coarse-graining.\nThe graph of area covered by the cracks versus minimum crack-width resolved,\nscales with the film thickness. Curves representing crack area for different\nthickness can thus be made to collapse onto a single curve.",
        "positive": "Intermolecular adhesion in conducting polymers: We analyze the interaction of two conducting, charged polymer chains in\nsolution using a minimal model for their electronic degrees of freedom. We show\nthat a crossing of the two chains in which the polymers pass within Angstroms\nof each other leads to a decrease of the electronic energy of the combined\nsystem that is significantly larger than the thermal energy and thus promotes\ninterchain aggregation. We consider the competition of this attractive\ninteraction with the screened electrostatic repulsion and thereby propose a\nphase diagram for such polymers in solution; depending on the charge density\nand persistence length of the chains, the polymers may be unbound, bound in\nloose, braid-like structures, or tightly bound in a parallel configuration."
    },
    {
        "anchor": "Spin waves in a Bose-condensed atomic spin chain: The spin dynamics of atomic Bose-Einstein condensates confined in a\none-dimensional optical lattice is studied. The condensates at each lattice\nsite behave like spin magnets that can interact with each other through both\nthe light-induced dipole-dipole interaction and the static magnetic\ndipole-dipole interaction. We show how these site-to-site dipolar interactions\ncan distort the ground state spin orientations and lead to the excitation of\nspin waves. The dispersion relation of the spin waves is studied and possible\ndetection schemes are proposed.",
        "positive": "Multispeckle diffusing-wave spectroscopy: a tool to study slow\n  relaxation and time-dependent dynamics: A multispeckle technique for efficiently measuring correctly\nensemble-averaged intensity autocorrelation functions of scattered light from\nnon-ergodic and/or non-stationary systems is described.\n  The method employs a CCD camera as a multispeckle light detector and a\ncomputer-based correlator, and permits the simultaneous calculation of up to\n500 correlation functions, where each correlation function is started at a\ndifferent time.\n  The correlation functions are calculated in real time and are referenced to a\nunique starting time.\n  The multispeckle nature of the CCD camera detector means that a true ensemble\naverage is calculated; no time averaging is necessary.\n  The technique thus provides a \"snapshot\" of the dynamics, making it\nparticularly useful for non-stationary systems where the dynamics are changing\nwith time.\n  Delay times spanning the range from 1 ms to 1000 s are readily achieved with\nthis method.\n  The technique is demonstrated in the multiple scattering limit where\ndiffusing-wave spectroscopy theory applies.\n  The technique can also be combined with a recently-developed two-cell\ntechnique that can measure faster decay times.\n  The combined technique can measure delay times from 10 ns to 1000 s.\n  The method is peculiarly well suited for studying aging processes in soft\nglassy materials, which exhibit both short and long relaxation times,\nnon-ergodic dynamics, and slowly-evolving transient behavior."
    },
    {
        "anchor": "Dynamics of fluids in quenched-random potential energy landscapes: a\n  mode-coupling theory approach: Motivated by a number of recent experimental and computational studies of the\ndynamics of fluids plunged in quenched-disordered external fields, we report on\na theoretical investigation of this topic within the framework of the\nmode-coupling theory, based on the simple model of the hard-sphere fluid in a\nGaussian random field. The possible dynamical arrest scenarios driven by an\nincrease of the disorder strength and/or of the fluid density are mapped, and\nthe corresponding evolutions of time-dependent quantities typically used for\nthe characterization of anomalous self-diffusion are illustrated with detailed\ncomputations. Overall, a fairly reasonable picture of the dynamics of the\nsystem at hand is outlined, which in particular involves a non-monotonicity of\nthe self-diffusion coefficient with fluid density at fixed disorder strength,\nin agreement with experiments. The disorder correlation length is shown to have\na strong influence on the latter feature.",
        "positive": "Membrane Heterogeneity: Manifestation of a Curvature-Induced\n  Microemulsion: To explain the appearance of heterogeneities in the plasma membrane, I\npropose a hypothesis which begins with the observation that fluctuations in the\nmembrane curvature are coupled to the difference between compositions in one\nleaf and the other. Because of this coupling, the most easily excited\nfluctuations can occur at non-zero wavenumbers. When the coupling is\nsufficiently strong, it is well-known that it leads to microphase separation\nand modulated phases. I note that when the coupling is less strong, the\ntendency towards modulation remains manifest in a liquid phase that exhibits\ntransient structure of a characteristic size; that is, it is a microemulsion.\nThe characteristic size of the fluctuating domains is estimated to be on the\norder of 100 nm, and experiments to verify this hypothesis are proposed."
    },
    {
        "anchor": "Periodic Cylindrical Bilayers Self-Assembled from Diblock Polymers: Amphiphilic polymers in aqueous solutions can self-assemble to form bilayer\nmembranes, and their elastic properties can be captured by the well-known\nHelfrich model involving several elastic constants. In this paper, we employ\nthe self-consistent field model to simulate sinusoidal bilayers self-assembled\nfrom diblock copolymers where a proper constraint term is introduced to\nstabilize periodic bilayers with prescribed amplitudes. Then, we devise several\nmethods to extract the shape of these bilayers and examine the accuracy of the\nfree energy predicted by the Helfrich model. Numerical results show that when\nthe bilayer curvature is small, the Helfrich model predicts the excess free\nenergy more accurately. However, when the curvature is large, the accuracy\nheavily depends on the method used to determine the shape of the bilayer. In\naddition, the dependence of free energy on interaction strength, constraint\namplitude, and constraint period are systematically studied. Moreover, we\nobtain certain periodic cylindrical bilayers that are equilibrium states of the\nself-consistent field model, which agree with the theoretical predictions made\nby the shape equations.",
        "positive": "Multiscale simulation of a polymer melt flow between two coaxial\n  cylinders under nonisothermal conditions: We successfully extend a multiscale simulation (MSS) method to nonisothermal\nwell-entangled polymer melt flows between two coaxial cylinders. In the\nmultiscale simulation, the macroscopic flow system is connected to a number of\nmicroscopic systems through the velocity gradient tensor, stress tensor and\ntemperature. At the macroscopic level, in addition to the momentum balance\nequation, we consider the energy balance equation, where heat generation plays\nan important role not only in the temperature distribution but also in the flow\nprofile. At the microscopic level, a dual slip-link model is employed for\nwell-entangled polymers. To incorporate the temperature effect into the\nmicroscopic systems, we used the time-temperature superposition rule for the\nslip-link model, in which the temperature dependence of the parameters is not\nknown; on the other hand, the way to take into account the temperature effect\nin the macroscopic equations has been well established. We find that the\nextended multiscale simulation method is quite effective in revealing the\nrelation between nonisothermal polymeric flows for both steady and transient\ncases and the microscopic states of polymer chains expressed by primitive paths\nand slip-links. It is also found that the temperature-dependent\nreptation-time-based Weissenberg number is a suitable measure for understanding\nthe extent of the polymer chain deformation in the range of the shear rate used\nin this study."
    },
    {
        "anchor": "Gibbs paradox and a possible mechanism of like-charge attraction in\n  colloids: Based on a reconsideration of the Gibbs paradox, we show that a residual,\nnon-extensive term in entropy turns up upon mixing identical particles, whether\nthey are indistinguishable or not. The positive contribution from this residual\nentropy leads to a decrease in free energy, and we suggest that this entropic\nmechanism may serve as a source of like-charge attractions between a pair of\ncolloidal particles or other macroions. For a system of two colloidal particles\nalong with their neutralizing counterions, such decrease in free energy is of a\nfew thermal energies and therefore crucial to the effective interaction between\nthe particles.",
        "positive": "Modeling Gel Swelling Equilibrium in Mean-Field: From explicit Models to\n  Poisson-Boltzmann: We develop a double mean-field theory for charged macrogels immersed in\nelectrolyte solutions in the spirit of the cell model approach. We first\ndemonstrate that the equilibrium sampling of a single explicit coarse-grained\ncharged polymer in a cell yields accurate predictions of the swelling\nequilibrium if the geometry is suitably chosen and all pressure contributions\nhave been incorporated accurately. We then replace the explicit flexible chain\nby a suitably modeled penetrable charged rod that allows to compute all\npressure terms within the Poisson-Boltzmann approximation. This model, albeit\ncomputationally cheap, yields excellent predictions of swelling equilibria\nunder varying chain length, polymer charge fraction, and external reservoir\nsalt concentrations when compared to coarse-grained molecular dynamics\nsimulations of charged macrogels. We present an extension of the model to the\nexperimentally relevant cases of pH-sensitive gels."
    },
    {
        "anchor": "Two-level system with a thermally fluctuating transfer matrix element:\n  Application to the problem of DNA charge transfer: Charge transfer along the base-pair stack in DNA is modeled in terms of\nthermally-assisted tunneling between adjacent base pairs. Central to our\napproach is the notion that tunneling between fluctuating pairs is rate-limited\nby the requirement of their optimal alignment. We focus on this aspect of the\nprocess by modeling two adjacent base pairs in terms of a classical damped\noscillator subject to thermal fluctuations as described by a Fokker-Planck\nequation. We find that the process is characterized by two time scales, a\nresult that is in accord with experimental findings.",
        "positive": "Dynamically-Stabilized Pores in Bilayer Membranes: Zhelev and Needham have recently created large, quasi-stable pores in\nartificial lipid bilayer vesicles [Biochim. Biophys. Acta 1147 (1993) 89].\nInitially created by electroporation, the pores remain open for up to several\nseconds before quickly snapping shut. This result is surprising in light of the\nlarge line tension for holes in bilayer membranes and the rapid time scale for\nclosure of large pores. We show how pores can be dynamically stabilized via a\nnew feedback mechanism. We also explain quantitatively the observed sudden pore\nclosure as a tangent bifurcation. Finally we show how Zhelev and Needham's\nexperiment can be used to measure accurately the pore line tension, an\nimportant material parameter. For their SOPC/CHOL mixture we obtain a line\ntension of 2.6 10^{-6} erg/cm."
    },
    {
        "anchor": "Influence of lateral confinement on granular flows: comparison between\n  shear-driven and gravity-driven flows: The properties of confined granular flows are studied through discrete\nnumerical simulations. Two types of flows with different boundaries are\ncompared: (i) gravity-driven flows topped with a free surface and over a base\nwhere erosion balances accretion (ii) shear-driven flows with a constant\npressure applied at their top and a bumpy bottom moving at constant velocity.\nIn both cases we observe shear localization over or/and under a creep zone. We\nshow that, although the different boundaries induce different flow properties\n(e.g. shear localization of transverse velocity profiles), the two types of\nflow share common properties like (i) a power law relation between the granular\ntemperature and the shear rate (whose exponent varies from 1 for dense flows to\n2 for dilute flows) and (ii) a weakening of friction at the sidewalls which\ngradually decreases with the depth within the flow.",
        "positive": "The configurational space of colloidal patchy polymers with\n  heterogeneous sequences: In this work we characterize the configurational space of a short chain of\ncolloidal particles as function of the range of directional and heterogeneous\nisotropic interactions. The individual particles forming the chain are colloids\ndecorated with patches that act as interaction sites between them. We show,\nusing computer simulations, that it is possible to sample the relative\nprobability of occurrence of a structure with a sequence in the space of all\npossible realizations of the chain. The results presented here represent a\nfirst attempt to map the space of possible configurations that a chain of\ncolloidal particles may adopt. Knowledge of such a space is crucial for a\npossible application of colloidal chains as models for designable\nself-assembling systems."
    },
    {
        "anchor": "Long-time dynamics of Rouse-Zimm polymers in dilute solutions with\n  hydrodynamic memory: The dynamics of flexible polymers in dilute solutions is studied taking into\naccount the hydrodynamic memory, as a consequence of fluid inertia. As distinct\nfrom the Rouse-Zimm (RZ) theory, the Boussinesq friction force acts on the\nmonomers (beads) instead of the Stokes force, and the motion of the solvent is\ngoverned by the nonstationary Navier-Stokes equations. The obtained generalized\nRZ equation is solved approximately. It is shown that the time correlation\nfunctions describing the polymer motion essentially differ from those in the RZ\nmodel. The mean-square displacement (MSD) of the polymer coil is at short times\n\\~ t^2 (instead of ~ t). At long times the MSD contains additional (to the\nEinstein term) contributions, the leading of which is ~ t^(1/2). The relaxation\nof the internal normal modes of the polymer differs from the traditional\nexponential decay. It is displayed in the long-time tails of their correlation\nfunctions, the longest-lived being ~ t^(-3/2) in the Rouse limit and t^(-5/2)\nin the Zimm case, when the hydrodynamic interaction is strong. It is discussed\nthat the found peculiarities, in particular an effectively slower diffusion of\nthe polymer coil, should be observable in dynamic scattering experiments.",
        "positive": "Nanoconfined fluids: Uniqueness of water compared to other liquids: Nanoconfinement can drastically change the behavior of liquids, puzzling us\nwith counterintuitive properties. Moreover, it is relevant in applications,\nincluding decontamination and crystallization control. It still lacks a\nsystematic analysis for fluids with different bulk properties. Here we fill\nthis gap. We compare, by molecular dynamics simulations, three different\nliquids in a graphene slit pore: (A) A simple fluid, such as argon, described\nby a Lennard-Jones potential; (B) An anomalous fluid, such as a liquid metal,\nmodeled with an isotropic core-softened potential; (C) Water, the prototypical\nanomalous liquid, with directional hydrogen bonds. We study how the slit-pore\nwidth affects the structure, thermodynamics, and dynamics of the fluids. We\ncheck that all the fluids, as expected, show similar oscillating properties by\nchanging the pore size. However, the nature of the free-energy minima for the\nthree fluids is quite different: i) only for the simple liquid all the minima\nare energy-driven, while their structural order increases with decreasing\nslit-pore width; ii) only for the isotropic core-softened potential all the\nminima are entropy-driven, while the energy in the minima increases with\ndecreasing slit-pore width; iii) only the water has a changing nature of the\nminima: the monolayer minimum is entropy-driven, at variance with the simple\nliquid, while the bilayer minimum is energy-driven, at variance with the other\nanomalous liquid. Also, water diffusion has a large increase for sub-nm\nslit-pores, becoming faster than bulk. Instead, the other two fluids have\ndiffusion oscillations much smaller than water slowing down for decreasing\nslit-pore width. Our results clarify that nanoconfined water is unique compared\nto other (simple or anomalous) fluids under similar confinement, and are\npossibly relevant in nanopores applications, e.g., in water purification from\ncontaminants."
    },
    {
        "anchor": "Universal two-component dynamics in supercritical fluids: Despite the technological importance of supercritical fluids, controversy\nremains about the details of their microscopic dynamics. In this work, we study\nfour supercritical fluid systems -- water, Si, Te, and Lennard-Jones fluid --\n\\emph{via} classical molecular dynamics simulations. A universal two-component\nbehavior is observed in the intermolecular dynamics of these systems, and the\nchanging ratio between the two components leads to a crossover from liquidlike\nto gaslike dynamics, most rapidly around the Widom line. We find evidence to\nconnect the liquidlike component dominating at lower temperatures with\nintermolecular bonding, and the component prominent at higher temperatures with\nfree-particle, gaslike dynamics. The ratio between the components can be used\nto describe important properties of the fluid, such as its self-diffusion\ncoefficient, in the transition region. Our results provide insight into the\nfundamental mechanism controlling the dynamics of supercritical fluids, and\nhighlight the role of spatiotemporally inhomogenous dynamics even in\nthermodynamic states where no large-scale fluctuations exist in the fluid.",
        "positive": "Solvent-mediated interactions between nanoparticles at fluid interfaces: We investigate the solvent mediated interactions between nanoparticles\nadsorbed at a liquid-vapor interface in comparison to the solvent mediated\ninteractions in the bulk liquid and vapor phases of a Lennard-Jones solvent.\nMolecular dynamics simulation data for the latter are in good agreement with\nresults from integral equations in the reference functional approximation and a\nsimple geometric approximation. Simulation results for the solvent mediated\ninteractions at the interface differ markedly from the interactions of the\nparticles in the corresponding bulk phases. We find that at short interparticle\ndistances the interactions are considerably more repulsive than those in either\nbulk phase. At long interparticle distances we find evidence for a long-ranged\nattraction. We discuss these observations in terms of interfacial interactions,\nnamely, the three-phase line tension that would operate at short distances, and\ncapillary wave interactions for longer interparticle distances."
    },
    {
        "anchor": "Power-Law Stretching of Associating Polymers in Steady-State Extensional\n  Flow: We present a tube model for the Brownian dynamics of associating polymers in\nextensional flow. In linear response, the model confirms the analytical\npredictions for the sticky diffusivity by Leibler- Rubinstein-Colby theory.\nAlthough a single-mode DEMG approximation accurately describes the transient\nstretching of the polymers above a 'sticky' Weissenberg number (product of the\nstrain rate with the sticky-Rouse time), the pre-averaged model fails to\ncapture a remarkable development of a power-law distribution of stretch in\nsteady-state extensional flow: while the mean stretch is finite, the\nfluctuations in stretch may diverge. We present an analytical model that shows\nhow strong stochastic forcing drive the long tail of the distribution, gives\nrise to rare events of reaching a threshold stretch and constitutes a framework\nwithin which nucleation rates of flow-induced crystallization may understood in\nsystems of associating polymers under flow. The model also exemplifies a wide\nclass of driven systems possessing strong, and scaling, fluctuations.",
        "positive": "Magic angles and cross-hatching instability in hydrogel fracture: The full 2D analysis of roughness profiles of fracture surfaces resulting\nfrom quasi-static crack propagation in gelatin gels reveals an original\nbehavior characterized by (i) strong anisotropy with maximum roughness at\n$V$-independent symmetry-preserving angles, (ii) a sub-critical instability\nleading, below a critical velocity, to a cross-hatched regime due to straight\nmacrosteps drifting at the same magic angles and nucleated on crack-pinning\nnetwork inhomogeneities. Step height values are determined by the width of the\nstrain-hardened zone, governed by the elastic crack blunting characteristic of\nsoft solids with breaking stresses much larger that low strain moduli."
    },
    {
        "anchor": "How droplets dry on stretched soft substrates: Liquid droplets usually wet smooth and homogeneous substrates isotropically.\nRecent research works have revealed that droplets sit, slide and spread\nanisotropically on uniaxially stretched soft substrates, showing an enhanced\nwettability and contact line mobility along the stretching direction. This\nphenomenon arises from the anisotropic deformation of the substrate below the\ncontact line. Here, we investigate how the stretching of soft substrates\naffects droplets drying. We observe that water droplet evaporates with an\nelongated non-circular contact line on the stretched substrates and switches\nthe elongation direction during evaporation. The contact line velocity and its\ntemporal evolution depend on the orientation of the contact line relative to\nthe stretching direction. On the substrate stretched by 250%, the contact line\nrecedes about 20% of the droplet lifetime earlier along the stretching\ndirection and faster than its perpendicular direction. When nanoparticles are\nadded into the liquid, the circular deposition pattern, i.e., the so-called\ncoffee-ring, becomes elongated along the direction perpendicular to the\nstretching direction. Particularly, such non-circular deposition pattern\nexhibits periodic height gradients along its rim. The finer structure of the\npattern can be controlled by applying different stretching ratios to the soft\nsubstrate and thus are correlated to the anisotropic surface stresses near the\ncontact line.",
        "positive": "Intrinsic water transport in moisture-capturing hydrogels: Moisture-capturing hydrogels have emerged as attractive sorbent materials\ncapable of converting ambient humidity into liquid water. Recent works have\ndemonstrated exceptional water capture capabilities of hydrogels, while\nsimultaneously, exploring different strategies to accelerate water capture and\nrelease. However, on the material level, an understanding of the intrinsic\ntransport properties of moisture-capturing hydrogels is currently missing,\nwhich hinders their rational design. In this work, we combine absorption and\ndesorption experiments of macroscopic hydrogel samples in pure-vapor with\nmodels of water diffusion in the hydrogels to demonstrate the first\nmeasurements of the intrinsic water diffusion coefficient in hydrogel-salt\ncomposites. Based on these insights, we pattern hydrogels with micropores to\nsignificantly decrease the required absorption and desorption time by 19% and\n72%, respectively, while reducing the total water capacity of the hydrogel by\nonly 4%. Thereby, we provide an effective strategy towards hydrogel material\noptimization, with a particular significance in pure-vapor environments."
    },
    {
        "anchor": "A differential equation for the Saffman-Taylor finger: We develop a stream function approach for the horizontal Hele-Shaw,\nSaffman-Taylor finger. The model yields a nonlinear time-dependent differential\nequation. The finger widths derived from the equation are\n$1>\\lambda>\\frac{1}{\\sqrt{5}}$, in units of half the width of the Hele-Shaw\ncell, in accordance with observation. The equation contains the correct\ndispersion relation for the creation of the finger instability. In an\naccompanying paper the stationary solutions of the equation are found\nnumerically.",
        "positive": "Thermal and structural properties of ionic fluids: The electrostatic interaction in ionic fluids is well-known to give rise to a\ncharacteristic phase behavior and structure. Sometimes its long range is\nproposed to single out the electrostatic potential over other interactions with\nshorter ranges. Here the importance of the range for the phase behavior and the\nstructure of ionic fluids is investigated by means of grandcanonical Monte\nCarlo simulations of the lattice restricted primitive model (LRPM). The\nlong-ranged electrostatic interaction is compared to various types of\nshort-ranged potentials obtained by sharp and/or smooth cut-off schemes.\nSharply cut off electrostatic potentials are found to lead to a strong\ndependence of the phase behavior and the structure on the cut-off radius.\nHowever, when combined with a suitable additional smooth cut-off, the\nshort-ranged LRPM is found to exhibit quantitatively the same phase behavior\nand structure as the conventional long-ranged LRPM. Moreover, the\nStillinger-Lovett perfect screening property, which is well-known to be\ngenerated by the long-ranged electrostatic potential, is also fulfilled by\nshort-ranged LRPMs with smooth cut-offs. By showing that the characteristic\nphase behavior and structure of ionic fluids can also be found in systems with\nshort-ranged potentials, one can conclude that the decisive property of the\nelectrostatic potential in ionic fluids is not the long range but rather the\nvalency dependence."
    },
    {
        "anchor": "The Observation of Formation and Annihilation of Solitons and Standing\n  Strain Wave Superstructures in a Two-Dimensional Colloidal Crystal: Confining a colloidal crystal within a long narrow channel produced by two\nparallel walls can be used to impose a meso-scale superstructure of a\npredominantly mechanical elastic character [Chui et al., EPL 2008, 83, 58004].\nWhen the crystal is compressed in the direction perpendicular to the walls, we\nobtain a structural transition when the number of rows of particles parallel to\nthe walls decreases by one. All the particles of this vanishing row are\ndistributed throughout the crystal. If the confining walls are structured (say\nwith a corrugation along the length of the walls), then these extra particles\nare distributed neither uniformly nor randomly; rather, defect structures are\ncreated along the boundaries resembling \"soliton staircases\", inducing a\nnon-uniform strain pattern within the crystal. Here we study the conditions of\nstability, formation and annihilation of these solitons using a coarse grained\ndescription of the dynamics. The processes are shown by comparing superimposed\nconfigurations as well as molecular animations obtained from our simulations.\nAlso the corresponding normal and shear stresses during the transformation are\ncalculated. A study of these dynamical processes should be useful for\ncontrolling strain wave superstructures in the self-assembly of various nano-\nand meso scaled particles.",
        "positive": "Microscopic Description of Thermodynamics of Lipid Membrane at\n  Liquid-Gel Phase Transition: A microscopic model of the lipid membrane is constructed that provides\nanalytically tractable description of the physical mechanism of the first order\nliquid-gel phase transition. We demonstrate that liquid-gel phase transition is\ncooperative effect of the three major interactions: inter-lipid van der Waals\nattraction, steric repulsion and hydrophobic tension. The model explicitly\nshows that temperature-dependent inter-lipid steric repulsion switches the\nsystem from liquid to gel phase when the temperature decreases. The switching\nmanifests itself in the increase of lateral compressibility of the lipids as\nthe temperature decreases, making phase with smaller area more preferable below\nthe transition temperature. The model gives qualitatively correct picture of\nabrupt change at transition temperature of the area per lipid, membrane\nthickness and volume per hydrocarbon group in the lipid chains. The calculated\ndependence of phase transition temperature on lipid chain length is in\nquantitative agreement with experimental data. Steric repulsion between the\nlipid molecules is shown to be the only driver of the phase transition, as van\nder Waals attraction and hydrophobic tension are weakly temperature dependent."
    },
    {
        "anchor": "Quantized ionic conductance in nanopores: Ionic transport in nanopores is a fundamentally and technologically important\nproblem in view of its occurrence in biological processes and its impact on\nnovel DNA sequencing applications. Using microscopic calculations, here we show\nthat ion transport may exhibit strong nonlinearities as a function of the pore\nradius reminiscent of the conductance quantization steps as a function of the\ntransverse cross section of quantum point contacts. In the present case,\nhowever, conductance steps originate from the break up of the hydration layers\nthat form around ions in aqueous solution. Once in the pore, the water\nmolecules form wavelike structures due to multiple scattering at the surface of\nthe pore walls and interference with the radial waves around the ion. We\ndiscuss these effects as well as the conditions under which the step-like\nfeatures in the ionic conductance should be experimentally observable.",
        "positive": "Balance of forces in simulated bilayers: Two kinds of simulated bilayers are described and the results are reported\nfor lateral tension and for partial contributions of intermolecular forces to\nit.Data for a widest possible range of areas per surfactant head, from tunnel\nformation through tensionless state, transition to floppy bilayer,to its\ndisintegration, are reported and discussed. The significance of the tensionless\nstate, is discussed. Conclusions: (1) the tensionless state is a\ncoincidence;(2) the transition from extended to floppy bilayer occurs nearby\nand has hallmarks of a phase transition (3) there is no theory of that\ntransition.(4)The lateral tension of the floppy bilayer scales with size; that\nof the extended bilayer does not depend on size. (4) The drumhead model not\nappropriate for interfaces as these fluctuate via diffusion.(5) The radius of\ngyration also! shows a discontinuity."
    },
    {
        "anchor": "Measuring Heat Flux Beyond Fourier's law: We use nonequilibrium molecular dynamics (NEMD) to explore the effect of\nshear flow on heat flux. By simulating a simple fluid in a channel bounded by\ntethered atoms, the heat flux is computed for two systems: a temperature driven\none with no flow and a wall driven, Couette flow system. The results for the\ntemperature driven system give the Fourier's law thermal conductivity, which is\nshown to agree well with experiments. Through comparison of the two systems, we\nquantify the additional components of the heat flux parallel and normal to the\nwalls due to shear flow. To compute the heat flux in the flow direction, the\nIrving-Kirkwood equations are integrated over a volume, giving the so-called\nvolume average form, and they are also manipulated to get expressions for the\nsurface averaged and method of planes forms. The method of planes and volume\naverage forms are shown to give equivalent results for the heat flux when using\nsmall volumes. The heat flux in the flow direction is obtained consistently\nover a range of simulations, and it is shown to vary linearly with strain rate,\nas predicted by theory. The additional strain rate dependent component of the\nheat flux normal to the wall is obtained by fitting the strain rate dependence\nof the heat flux to the expected form. As a result, the additional terms in the\nthermal conductivity tensor quantified in this work should be experimentally\ntestable.",
        "positive": "Lattice Knots in a Slab: In this paper the number and lengths of minimal length lattice knots confined\nto slabs of width $L$, is determined. Our data on minimal length verify the\nresults by Sharein et.al. (2011) for the similar problem, expect in a single\ncase, where an improvement is found. From our data we construct two models of\ngrafted knotted ring polymers squeezed between hard walls, or by an external\nforce. In each model, we determine the entropic forces arising when the lattice\npolygon is squeezed by externally applied forces. The profile of forces and\ncompressibility of several knot types are presented and compared, and in\naddition, the total work done on the lattice knots when it is squeezed to a\nminimal state is determined."
    },
    {
        "anchor": "Nonmonotonic behavior in the dense assemblies of active colloids: We study experimentally a sediment of self-propelled Brownian particles with\ndensities ranging from dilute to ergodic supercooled, to nonergodic glass, to\nnonergodic polycrystal. In a compagnon letter, we observe a nonmonotonic\nresponse to activity of relaxation of the nonergodic glass state: a dramatic\nslowdown when particles become weakly self-propelled, followed by a speedup at\nhigher activities. Here we map ergodic supercooled states to standard passive\nglassy physics, provided a monotonic shift of the glass packing fraction and\nthe replacement of the ambient temperature by the effective temperature.\nHowever we show that this mapping fails beyond glass transition. This failure\nis responsible for the nonmonotonic response. Furthermore, we generalize our\nfinding by examining the dynamical response of an other class of nonergodic\nsystems : polycrystals. We observe the same nonmonotinic response to activity.\nTo explain this phenomenon, we measure the size of domains were particles move\nin the same direction. This size also shows a nonmonotonic response, with small\nlengths corresponding to slow relaxation. This suggests that the failure of the\nmapping of nonergodic active states to a passive situation is general and is\nlinked to anisotropic relaxation mechanisms specific to active matter.",
        "positive": "Relaxation and Intermediate Asymptotics of a Rectangular Trench in a\n  Viscous Film: The surface of a thin liquid film with nonconstant curvature flattens as a\nresult of capillary forces. While this leveling is driven by local curvature\ngradients, the global boundary conditions greatly influence the dynamics. Here,\nwe study the evolution of rectangular trenches in a polystyrene nanofilm.\nInitially, when the two sides of a trench are well separated, the asymmetric\nboundary condition given by the step height controls the dynamics. In this\ncase, the evolution results from the leveling of two noninteracting steps. As\nthe steps broaden further and start to interact, the global symmetric boundary\ncondition alters the leveling dynamics. We report on full agreement between\ntheory and experiments for: the capillary-driven flow and resulting time\ndependent height profiles; a crossover in the power-law dependence of the\nviscous energy dissipation as a function of time as the trench evolution\ntransitions from two noninteracting to interacting steps; and the convergence\nof the profiles to a universal self-similar attractor that is given by the\nGreen's function of the linear operator describing the dimensionless linearized\nthin film equation."
    },
    {
        "anchor": "Two-Step Adsorption of $PtCl_6^{2-}$ Complexes at a Charged Langmuir\n  Monolayer: Role of Hydration and Ion Correlations: Anion exchange at positively charged interfaces plays an important role in a\nvariety of physical and chemical processes. However, the molecular scale\ndetails of these processes, especially with heavy and large anionic complexes,\nare not well-understood. We studied the adsorption of $PtCl_6^{2-}$ anionic\ncomplexes to floating DPTAP monolayers in the presence of excess $Cl^-$ as a\nfunction of the bulk chlorometalate concentration. In situ x-ray scattering and\nfluorescence measurements, which are element and depth sensitive, show that the\nchlorometalate ions only adsorb in the diffuse layer at lower concentrations,\nwhile they adsorb predominantly in the Stern layer at higher concentrations.\nThe response of DPTAP molecules to the adsorbed ions is determined\nindependently by grazing incidence x-ray diffraction, and supports this\npicture. Molecular dynamics simulations further elucidate the nanoscale\nstructure of the interfacial complexes. The results suggest that ion hydration\nand ion-ion correlations play a key role in the competitive adsorption process.",
        "positive": "The viscoelastic and anelastic responses of amorphous polymers in the\n  vicinity of the glass transition temperature: The time-dependent response of polystyrene and poly(methyl methacrylate) is\nstudied in isothermal long-term shear creep tests at small strains and various\ntemperatures in the vicinity of the glass transition point. A micromechanical\nmodel is derived to describe the experimental results. Constitutive equations\nare developed under the assumption that the behavior of amorphous polymers is\ngoverned by two micro-mechanisms: rearrangement of cooperatively relaxing\nregions (CRR) reflects the viscoelastic response, whereas displacement of CRRs\nwith respect to each other is responsible for the anelastic response. It is\ndemonstrated that some critical temperature exists slightly above the glass\ntransition temperature, where the dependences of adjustable parameters on\ntemperature are dramatically changed. The critical temperature is associated\nwith transition from dynamic heterogeneity in amorphous polymers to static\ninhomogeneity."
    },
    {
        "anchor": "The Design and Investigation of the Self-Assembly of Dimers with two\n  Nematic Phases: A series of non-symmetric dimers were synthesised containing either\ncyanobiphenyl or difluoroterphenyl moieties on one side and a range of long,\nshort, bent, polar or apolar mesogens on the other side of the molecules. The\ndielectric anisotropy of the mesogens was varied systematically. The systems\nwere characterised by differential scanning calorimetry (DSC), optical\npolarizing microscopy (OPM) and detailed X-ray diffraction (XRD) studies, both\nin the nematic and the Nx phase. The results are compared and structure\nproperties relationships are discussed. A model for the assembly in the Nx\nphase is developed discussing Ntb structures, coaxial helices, swiss roll\nstructures and chiral domain formation.",
        "positive": "Nonaffine rubber elasticity for stiff polymer networks: We present a theory for the elasticity of cross-linked stiff polymer\nnetworks. Stiff polymers, unlike their flexible counterparts, are highly\nanisotropic elastic objects. Similar to mechanical beams stiff polymers easily\ndeform in bending, while they are much stiffer with respect to tensile forces\n(``stretching''). Unlike in previous approaches, where network elasticity is\nderived from the stretching mode, our theory properly accounts for the soft\nbending response. A self-consistent effective medium approach is used to\ncalculate the macroscopic elastic moduli starting from a microscopic\ncharacterization of the deformation field in terms of ``floppy modes'' --\nlow-energy bending excitations that retain a high degree of non-affinity. The\nlength-scale characterizing the emergent non-affinity is given by the ``fiber\nlength'' $l_f$, defined as the scale over which the polymers remain straight.\nThe calculated scaling properties for the shear modulus are in excellent\nagreement with the results of recent simulations obtained in two-dimensional\nmodel networks. Furthermore, our theory can be applied to rationalize bulk\nrheological data in reconstituted actin networks."
    },
    {
        "anchor": "Complete description of re-entrant phase behaviour in a charge variable\n  colloidal model system: In titration experiments with NaOH we have determined the full phase diagram\nof charged colloidal spheres in dependence on the particle density n, the\nparticle effective charge Zeff and the concentration of screening electrolyte c\nusing microscopy, light and Ultra Small Angle X-Ray Scattering (USAXS). For\nsufficiently large n the system crystallizes upon increasing Zeff at constant c\nand melts upon increasing c at only slightly altered Zeff. In contrast to\nearlier work equilibrium phase boundaries are consistent with a universal\nmelting line prediction from computer simulation, if the elasticity effective\ncharge is used. This charge accounts for both counter-ion condensation and many\nbody effects.",
        "positive": "The Role of Adhesion in the Mechanics of Crumpled Polymer Films: Crumpling of a thin film leads to a unique stiff yet lightweight structure.\nThe stiffness has been attributed to a complex interplay between four basic\nelements - smooth bends, sharp folds, localized points (developable cones), and\nstretching ridges - yet rigorous models of the structure are not yet available.\nIn this letter we show that adhesion, the attraction between surfaces within\nthe crumpled structure, is an important yet overlooked contributer to the\noverall strength of a crumpled film. Specifically, we conduct experiments with\ntwo different polymers films and compare the role of plastic deformation,\nelastic deformation and adhesion in crumpling. We use an empirical model to\ncapture the behaviour quantitatively, and use the model to show that adhesion\nleads to an order of magnitude increase in \"effective\" modulus. Going beyond\nstatics, we additionally conduct force recovery experiments. We show that once\nadhesion is accounted for, plastic and elastic crumpled films recover\nlogarithmically. The time constants measured through crumpling, interpreted\nwith our model, show an identical distribution as do the base materials\nmeasured in more conventional geometries."
    },
    {
        "anchor": "Thermodynamics of nano-cluster phases: a unifying theory: We propose a unifying, analytical theory accounting for the self-organization\nof colloidal systems in nano- or micro-cluster phases. We predict the\ndistribution of cluter sizes with respect to interaction parameters and colloid\nconcentration. In particular, we anticipate a proportionality regime where the\nmean cluster size grows proportionally to the concentration, as observed in\nseveral experiments. We emphasize the interest of a predictive theory in soft\nmatter, nano-technologies and biophysics.",
        "positive": "Dynamics of wetting explored with inkjet printing: An inkjet printer head, which is capable of depositing liquid droplets with a\nresolution of $22$ picoliters and high repeatability, is employed to\ninvestigate the wetting dynamics of drops printed on a horizontal plane as well\nas on a granular monolayer. For a sessile drop on a horizontal plane, we\ncharacterize the contact angle hysteresis, drop volume and contact line\ndynamics from side view images. We show that the evaporation rate scales with\nthe dimension of the contact line instead of the surface area of the drop. We\ndemonstrate that the system evolves into a closed cycle upon repeating the\ndepositing-evaporating process, owing to the high repeatability of the printing\nfacility. Finally, we extend the investigation to a granular monolayer in order\nto explore the interplay between liquid deposition and granular particles."
    },
    {
        "anchor": "Effect of Wall Friction on 2D Hopper Flow: We report here on experiments and simulations examining the effect of\nchanging wall friction on the gravity-driven flow of spherical particles in a\nvertical hopper. In 2D experiments and simulations, we observe that the\nexponent of the expected power-law scaling of mass flow rate with opening size\n(known as Beverloo's law) decreases as the coefficient of friction between\nparticles and wall increases, whereas Beverloo scaling works as expected in 3D.\nIn our 2D experiments, we find that wall friction plays the biggest role in a\nregion near the outlet comparable in height to the largest opening size.\nHowever, wall friction is not the only factor determining a constant rate of\nflow, as we observe a near-constant mass outflow rate in the 2D simulations\neven when wall friction is set to zero. We show in our simulations that an\nincrease in wall friction leaves packing fractions relatively unchanged, while\naverage particle velocities become independent of opening size as the\ncoefficient of friction increases. We track the spatial pattern of\ntime-averaged particle velocities and accelerations inside the hopper. We\nobserve that the hemisphere-like region above the opening where particles begin\nto accelerate is largely independent of opening size at finite wall friction.\nHowever, the magnitude of particle accelerations decreases significantly as\nwall friction increases, which in turn results in mean sphere velocities that\nno longer scale with opening size, consistent with our observations of mass\nflow rate scaling. The case of zero wall friction is anomalous, in that most of\nthe acceleration takes place near the outlet.",
        "positive": "First integrals for elastic curves: twisting instabilities of helices: We put forward a variational framework suitable for the study of curves whose\nenergies depend on their bend and twist degrees of freedom. By employing the\nmaterial curvatures to describe such elastic deformation modes, we derive the\nequilibrium equations representing the balance of forces and torques on the\ncurve. The conservation laws of the force and torque on the curve, stemming\nfrom the Euclidean invariance of the energy, allow us to obtain first integrals\nof the equilibrium equations. To illustrate this framework, we apply it to\ndetermine the first integrals for isotropic and anisotropic Kirchhoff elastic\nrods, whose energies are quadratic in the material curvatures. We use them to\nanalyze perturbatively the deformations of helices resulting from their\ntwisting. We examine three kinds of twisting instabilities on unstretchable\nhelices, characterized by their wavenumbers, depending on whether their\nboundaries are fixed, displaced along the radial direction or orthogonally to\nit. We also analyze perturbatively the effect of the bending anisotropy on the\ndeformed states, which introduces a coupling between deformation modes with\ndifferent wavenumbers."
    },
    {
        "anchor": "Spectral Shape of Relaxations in Silica Glass: Precise low-frequency light scattering experiments on silica glass are\npresented, covering a broad temperature and frequency range (9 GHz < \\nu < 2\nTHz). For the first time the spectral shape of relaxations is observed over\nmore than one decade in frequency. The spectra show a power-law low-frequency\nwing of the relaxational part of the spectrum with an exponent $\\alpha $\nproportional to temperature in the range 30 K < T < 200 K. A comparison of our\nresults with those from acoustic attenuation experiments performed at different\nfrequencies shows that this power-law behaviour rather well describes\nrelaxations in silica over 9 orders of magnitude in frequency. These findings\ncan be explained by a model of thermally activated transitions in double well\npotentials.",
        "positive": "Overcharging: The Crucial Role of Excluded Volume: In this Letter we investigate the mechanism for overcharging of a single\nspherical colloid in the presence of aqueous salts within the framework of the\nprimitive model by molecular dynamics (MD) simulations as well as\nintegral-equation theory. We find that the occurrence and strength of\novercharging strongly depends on the salt-ion size, and the available volume in\nthe fluid. To understand the role of the excluded volume of the microions, we\nfirst consider an uncharged system. For a fixed bulk concentration we find that\nupon increasing the fluid particle size one strongly increases the local\nconcentration nearby the colloidal surface and that the particles become\nlaterally ordered. For a charged system the first surface layer is built up\npredominantly by strongly correlated counterions. We argue that this a key\nmechanism to produce overcharging with a low electrostatic coupling, and as a\nmore practical consequence, to account for charge inversion with monovalent\naqueous salt ions."
    },
    {
        "anchor": "Fragmentation and depolymerization of non-covalently bonded filaments: Protein molecules often self-assemble by means of non-covalent physical bonds\nto form extended filaments, such as amyloids, F-actin, intermediate filaments,\nand many others. The kinetics of filament growth is limited by the disassembly\nrate, at which inter-protein bonds break due to the thermal motion. Existing\nmodels often assume that the thermal dissociation of subunits occurs uniformly\nalong the filament, or even preferentially in the middle, while the well-known\npropensity of F-actin to depolymerize from one end is mediated by biochemical\nfactors. Here, we show for a very general (and generic) model, using Brownian\ndynamics simulations and theory, that the breakup location along the filament\nis strongly controlled by the asymmetry of the binding force about the minimum,\nas well as by the bending stiffness of the filament. We provide the basic\nconnection between the features of the interaction potential between subunits\nand the breakup topology. With central-force (that is, fully flexible) bonds,\nthe breakup rate is always maximum in the middle of the chain, whereas for\nsemiflexible or stiff filaments this rate is either a minimum in the middle or\nflat. The emerging framework provides a unifying understanding of biopolymer\nfragmentation and depolymerization and recovers earlier results in its\ndifferent limits.",
        "positive": "Rayleigh waves in symmetry planes of crystals: explicit secular\n  equations and some explicit wave speeds: Rayleigh waves are considered for crystals possessing at least one plane of\nsymmetry. The secular equation is established explicitly for surface waves\npropagating in any direction of the plane of symmetry, using two different\nmethods. This equation is a quartic for the squared wave speed in general, and\na biquadratic for certain directions in certain crystals, where it may itself\nbe solved explicitly. Examples of such materials and directions are found in\nthe case of monoclinic crystals with the plane of symmetry at $x_3=0$. The\ncases of orthorhombic materials and of incompressible materials are also\ntreated."
    },
    {
        "anchor": "Blinking statistics of a molecular beacon triggered by end-denaturation\n  of DNA: We use a master equation approach based on the Poland-Scheraga free energy\nfor DNA denaturation to investigate the (un)zipping dynamics of a denaturation\nwedge in a stretch of DNA, that is clamped at one end. In particular, we\nquantify the blinking dynamics of a fluorophore-quencher pair mounted within\nthe denaturation wedge. We also study the behavioural changes in the presence\nof proteins, that selectively bind to single-stranded DNA. We show that such a\nsetup could be well-suited as an easy-to-implement nanodevice for sensing\nenvironmental conditions in small volumes.",
        "positive": "Extended $\u03bc(J)$-rheology for dense suspensions at oscillatory shear\n  flows: Recent studies have highlighted that oscillatory and time-dependent shear\nflows might help increase flowability of dense suspensions. While most focus\nhas been on cross-flows we here study a simple two-dimensional suspensions\nwhere we apply simultaneously oscillatory and stationary shear along the same\ndirection. We first show that the viscosities in this set-up significantly\ndecrease with an increasing magnitude of the oscillations, contrary to previous\nclaims. The decrease can be attributed to the large decrease in the number of\ncontacts and an altered microstructure as the magnitude of the oscillation is\nincreased. As a sub-result we find both an extension to the $\\mu(J)$-rheology,\na constitutive relationship between the shear stresses and the shear rate,\nvalid for pure oscillatory flows and with a higher shear-jammed packing\nfraction for suspensions composed of frictional particles compared to\nsteady-shear conditions."
    },
    {
        "anchor": "Field theory description of ion association in re-entrant phase\n  separation of polyampholytes: Phase separation of several different overall neutral polyampholyte species\n(with zero net charge) is studied in solution with two oppositely charged ion\nspecies that can form ion-pairs through an association reaction. A field theory\ndescription of the system, that treats polyampholyte charge sequence dependent\nelectrostatic interactions as well as excluded volume effects, is hereby given.\nInterestingly, analysis of the model using random phase approximation and field\ntheoretic simulation consistently show evidence of a re-entrant polyampholyte\nphase separation at high ion concentrations when there is an overall decrease\nof volume upon ion-association. As an illustration of the ramifications of our\ntheoretical framework, several polyampholyte concentration vs ion concentration\nphase diagrams under constant temperature conditions are presented to elucidate\nthe dependence of phase separation behavior on polyampholyte sequence charge\npattern as well as ion-pair dissociation constant, volumetric effects on ion\nassociation, solvent quality, and temperature.",
        "positive": "Spectral shape simplicity of viscous materials: A broad survey of viscoelastic data demonstrates that van der Waals,\nhydrogen-bonded, and ionic liquids, as well as polymeric, inorganic, and\nmetallic melts share a structural relaxation pattern virtually insensitive to\ntheir morphological details. This mechanical simplicity is connected with that\ncharacterizing the fast reorientation dynamics prevailing in liquids devoid of\na distinguishable secondary loss peak. By these means one is able to uncover a\ngeneric spectral pattern which rationalizes the recently reported\n\"universality\" of relaxation strength vs. stretching of the dielectric response\nof viscous liquids, significantly broadening the framework in which their\nrelaxation behavior is assessed."
    },
    {
        "anchor": "Shear rate threshold for the boundary slip in dense polymer films: The shear rate dependence of the slip length in thin polymer films confined\nbetween atomically flat surfaces is investigated by molecular dynamics\nsimulations. The polymer melt is described by the bead-spring model of linear\nflexible chains. We found that at low shear rates the velocity profiles acquire\na pronounced curvature near the wall and the absolute value of the negative\nslip length is approximately equal to thickness of the viscous interfacial\nlayer. At higher shear rates, the velocity profiles become linear and the slip\nlength increases rapidly as a function of shear rate. The gradual transition\nfrom no-slip to steady-state slip flow is associated with faster relaxation of\nthe polymer chains near the wall evaluated from decay of the time\nautocorrelation function of the first normal mode. We also show that at high\nmelt densities the friction coefficient at the interface between the polymer\nmelt and the solid wall follows power law decay as a function of the slip\nvelocity. At large slip velocities the friction coefficient is determined by\nthe product of the surface induced peak in the structure factor, temperature\nand the contact density of the first fluid layer near the solid wall.",
        "positive": "Stiffening of under-constrained spring networks under isotropic strain: Disordered spring networks are a useful paradigm to examine macroscopic\nmechanical properties of amorphous materials. Here, we study the elastic\nbehavior of under-constrained spring networks, i.e.\\ networks with more degrees\nof freedom than springs. While such networks are usually floppy, they can be\nrigidified by applying external strain. Recently, an analytical formalism has\nbeen developed to predict the mechanical network properties close to this\nrigidity transition. Here we numerically show that these predictions apply to\nmany different classes of spring networks, including phantom triangular,\nDelaunay, Voronoi, and honeycomb networks. The analytical predictions further\nimply that the shear modulus $G$ scales linearly with isotropic stress $T$\nclose to the rigidity transition; however, this seems to be at odds with recent\nnumerical studies suggesting an exponent between $G$ and $T$ that is smaller\nthan one for some network classes. Using increased numerical precision and\nshear stabilization, we demonstrate here that close to the transition linear\nscaling, $G\\sim T$, holds independent of the network class. Finally, we show\nthat our results are not or only weakly affected by finite-size effects,\ndepending on the network class."
    },
    {
        "anchor": "Compression and reswelling of microgel particles after an osmotic shock: We use dedicated microfluidic devices to expose soft hydrogel particles to a\nrapid change in the externally applied osmotic pressure and observe a\nnon-monotonic response: After an initial rapid compression the particle slowly\nreswells to approximately its original size. Using a simple phenomenological\nand a more elaborate poroelastic model, we extract important material\nproperties from a single microfluidic experiment, including the compressive\nmodulus, the gel permeability and the diffusivity of the osmolyte inside the\ngel. We expect our approach to be relevant to applications such as controlled\nrelease, chromatography, and responsive materials.",
        "positive": "Two-dimensional photonic crystal polarizer: A novel polarizer made from two-dimensional photonic bandgap materials was\ndemonstrated theoretically. This polarizer is fundamentally different from the\nconventinal ones. It can function in a wide frequency range with high\nperformance and the size can be made very compact, which renders it useful as a\nmicropolarizer in microoptics."
    },
    {
        "anchor": "Validity of the \"sharp-kink approximation\" for water and other fluids: The contact angle of a liquid droplet on a solid surface is a direct measure\nof fundamental atomic-scale forces acting between liquid molecules and the\nsolid surface. In this work, the validity is assessed of a simple equation,\nwhich approximately relates the contact angle of a liquid on a surface to its\ndensity, its surface tension, and the effective molecule-surface potential.\nThis equation is derived in the sharp-kink approximation, where the density\nprofile of the liquid is assumed to drop precipitously within one molecular\ndiameter of the substrate. It is found that this equation satisfactorily\nreproduces the temperature-dependence of the contact angle for helium on alkali\nmetal surfaces. The equation also seems be applicable to liquids such as water\non solid surfaces such as gold and graphite, based on a comparison of predicted\nand measured contact angles near room-temperature. Nevertheless, we conclude\nthat, to fully test the equation's applicability to fluids such as water, it\nremains necessary to measure the contact angle's temperature-dependence. We\nhypothesize that the effects of electrostatic forces can increase with\ntemperature, potentially driving the wetting temperature much higher and closer\nto the critical point, or lower, closer to room temperature, than predicted\nusing current theories.",
        "positive": "Dynamic shear responses of polymer-polymer interfaces: In multi-component soft matter, interface properties often play a key role in\ndetermining the properties of the overall system. The identification of the\ninternal dynamic structures in non-equilibrium situations requires the\ninterface rheology to be characterized. We have developed a method to quantify\nthe rheological contribution of soft interfaces and evaluate the dynamic\nmodulus of the interface. This method reveals that the dynamic shear responses\nof interfaces in bilayer systems comprising polypropylene and three different\npolyethylenes can be classified as having hardening and softening effects on\nthe overall system: a interface between linear long polymers becomes more\nelastic than the component polymers, while large polydispersity or\nlong-chain-branching of one component make the interface more viscous. We find\nthat the chain lengths and architectures of the component polymers, rather than\nequilibrium immiscibility, play an essential role in determining the interface\nrheological properties."
    },
    {
        "anchor": "Continuous Self Energy of Ions at the Dielectric Interface: We present a simple, unified theory for the self-energy of an ion near a\ndielectric interface. Our theory accounts for both the short-range (solvation)\nand long-range (image force) electrostatic forces, charge polarization induced\nby these forces, and the cavity energy. In contrast to previous models, our\nself energy is continuous across the interface and thus applicable to both the\nwater and air (oil) sides of the interface. With no fitting parameters, we\npredict the specific ion effect on the interfacial affinity of halogen anions\nat the water/air interface, and the strong adsorption of hydrophobic ions at\nthe water/oil interface, in agreement with experiments and atomistic\nsimulations.",
        "positive": "Crystallization of Simple Fluids: Relative Stability of f.c.c. and b.c.c\n  Structures: A free-energy functional for a crystal that contains both the symmetry\nconserved and symmetry broken parts of the direct pair correlation function is\ndeveloped. The free-energy functional is used to investigate the\ncrystallization of fluids interacting via the inverse power potential ;\n$u(r)=\\epsilon {(\\sigma/r)}^n$. In agreement with simulation results we find\nthat for $n=12$ the freezing is into close packed f.c.c structure while for\nsoft repulsions $(n\\leq 6)$ b.c.c phase is more stable."
    },
    {
        "anchor": "Polydisperse star polymer solutions: We analyze the effect of polydispersity in the arm number on the effective\ninteractions, structural correlations and the phase behavior of star polymers\nin a good solvent. The effective interaction potential between two star\npolymers with different arm numbers is derived using scaling theory. The\nresulting expression is tested against monomer-resolved molecular dynamics\nsimulations. We find that the theoretical pair potential is in agreement with\nthe simulation data in a much wider polydispersity range than other proposed\npotentials. We then use this pair potential as an input in a many-body theory\nto investigate polydispersity effects on the structural correlations and the\nphase diagram of dense star polymer solutions. In particular we find that a\npolydispersity of 10%, which is typical in experimental samples, does not\nsignificantly alter previous findings for the phase diagram of monodisperse\nsolutions.",
        "positive": "Robustness of FCS (Fluorescence Correlation Spectroscopy) with Quenchers\n  Present: Inspired by recent publications doubtful of the FCS technique, we scrutinize\nhow irreversible (static) and reversible (dynamic) quenching can influence the\ninterpretation of such data. We consider intermediate cases where the\nassessment of photophysics (static quenching, blinking-like triplet state\nrelaxation) influence on autocorrelation curves can be delicate if dye-labeled\nobjects diffuse on comparably-rapid time scales and use tryptophan as the\nquencher. As our example of small-molecule dye that diffuses rapidly, we mix\nquencher with Alexa 488 dye, and quenching is reflected in the fact that the\ndata become exceptionally noisy. This reflects the bidisperse population of\nquenched and unquenched dye when the time scales overlap between the processes\nof translational diffusion, quenching, and blinking. As our example of\nlarge-molecule dye-labeled object, we mixed quencher with dye-labeled bovine\nserum albumin. Diffusion, static quenching and blinking time scales are now\nseparated, and inferred translational diffusion now depends weakly on quencher.\nWe conclude that when the diffusing molecule is substantially slower to diffuse\nthan the time scale of photophysical processes of the fluorescent dye to which\nit is attached, influence of quenching is self-evident and the FCS\nautocorrelation curves give appropriate diffusion coefficient if correct\nfitting functions are chosen in the analysis."
    },
    {
        "anchor": "Microstructural understanding of the length and stiffness dependent\n  shear thinning in semi-dilute colloidal rods: Complex fluids containing low concentrations of slender colloidal rods can\ndisplay a high viscosity, while little flow is needed to thin the fluid. This\nfeature makes slender rods essential constituents in industrial applications\nand biology. Though this behaviour strongly depends on the rod-length, so far\nno direct relation could be identified. We employ a library of filamentous\nviruses to study the effect of rod size and flexibility on the zero-shear\nviscosity and shear-thinning behaviour. Rheology and small angle neutron\nscattering data are compared to a revised version of the standard theory for\nideally stiff rods, which incorporates a complete shear-induced dilation of the\nconfinement. While the earlier predicted length-independent pre-factor of the\nrestricted rotational diffusion coefficient is confirmed by varying the length\nand concentration of the rods, the revised theory correctly predicts the shear\nthinning behaviour as well as the underlying orientational order. These results\ncan be directly applied to understand the manifold systems based on rod-like\ncolloids and design new materials.",
        "positive": "Charge Transport in Dendrimer Melt using Multiscale Modeling Simulation: In this paper we present a theoretical calculation of the charge carrier\nmobility in two different dendrimeric melt system (Dendritic phenyl azomethine\nwith Triphenyl amine core and Dendritic Carbazole with Cyclic Phenylazomethine\nas core), which have recently been reported1 to increase the efficiency of\nDye-Sensitized solar cells (DSSCs) by interface modification. Our mobility\ncalculation, which is a combination of molecular dynamics simulation, first\nprinciples calculation and kinetic Monte Carlo simulation, leads to mobilities\nthat are in quantitative agreement with available experimental data. We also\nshow how the mobility depends on the dendrimer generation. Furthermore, we\nexamine the variation of mobility with external electric field and external\nreorganization energy. Physical mechanisms behind observed electric field and\ngeneration dependencies of mobility are also explored."
    },
    {
        "anchor": "Anomalous interfacial dynamics of single proton charges in binary\n  aqueous solutions: Understanding the dynamics of charge exchange between a solid surface and a\nliquid is fundamental to various situations, ranging from nanofiltration to\ncatalysis and electrochemistry. Charge transfer is ultimately determined by\nphysicochemical processes (surface group dissociation, ion adsorption, etc...)\noccurring in the few layers of molecules at the interface between the solid and\nthe liquid. Unfortunately, these processes remain largely uncharted due to the\nexperimental challenges in probing interfacial charge dynamics with\nsufficiently high spatial and temporal resolution. Here, we resolve at the\nsingle-charge scale, the dynamics of proton charges at the interface between an\nhBN crystal and binary mixtures of water and organic amphiphilic solvents (e.g.\nalcohol), evidencing a dramatic influence of solvation on interfacial dynamics.\nOur observations rely on the application of spectral Single Molecule\nLocalization Microscopy (sSMLM) to two types of optically active defects at the\nhBN surface, which act as intrinsic optical markers for both surface\nprotonation and interaction with apolar alkyl groups of the organic solvent. We\nuse sSMLM to reveal interfacial proton charge transport as a succession of\njumps between the titratable surface defects, mediated by the transport of the\nsolvated proton charge along the solid/liquid interface. By changing the\nrelative concentration of water in binary mixtures, we evidence a non-trivial\neffect on interfacial proton charge dynamics, leading at intermediate water\nconcentration to an increased affinity of the proton charge to the solid\nsurface, accompanied by an increased surface diffusivity. These measurements\nconfirm the strong role of solvation on interfacial proton charge transport and\nestablish the potential of single-molecule localization techniques to probe a\nwide range of dynamic processes at solid/liquid interfaces.",
        "positive": "Hyperuniform Active Chiral Fluids with Tunable Internal Structure: Large density fluctuations observed in active systems and hyperuniformity are\ntwo seemingly incompatible phenomena. However, the formation of hyperuniform\nstates has been recently predicted in non-equilibrium fluids formed by chiral\nparticles performing circular motion with the same handedness. Here we report\nevidence of hyperuniformity realized in a chiral active fluid comprised of\npear-shaped Quincke rollers of arbitrary handedness. We show that\nhyperuniformity and large density fluctuations, triggered by dynamic\nclustering, coexist in this system at different length scales. The system loses\nits hyperuniformity as the curvature of particles' motion increases\ntransforming them into localized spinners. Our results experimentally\ndemonstrate a novel hyperuniform active fluid and provide new insights into an\ninterplay between chirality, activity and hyperuniformity."
    },
    {
        "anchor": "Fatigue behavior of Cu-Zr metallic glasses under cyclic loading: The effect of oscillatory shear deformation on the fatigue life, yielding\ntransition, and flow localization in metallic glasses is investigated using\nmolecular dynamics simulations. We study a well-annealed Cu-Zr amorphous alloy\nsubjected to periodic shear at room temperature. We find that upon loading for\nhundreds of cycles at strain amplitudes just below a critical value, the\npotential energy at zero strain remains nearly constant and plastic events are\nhighly localized. By contrast, at strain amplitudes above the critical point,\nthe plastic deformation is gradually accumulated upon continued loading until\nthe yielding transition and the formation of a shear band across the entire\nsystem. Interestingly, when the strain amplitude approaches the critical value\nfrom above, the number of cycles to failure increases as a power-law function,\nwhich is consistent with the previous results on binary Lennard-Jones glasses.",
        "positive": "On phase behavior and dynamical signatures of charged colloidal\n  platelets: We investigate the competition between anisotropic excluded-volume and\nrepulsive electrostatic interactions in suspensions of thin charged colloidal\ndiscs, by means of Monte-Carlo simulations and dynamical characterization of\nthe structures found. We show that the original intrinsic anisotropy of the\nelectrostatic potential between charged platelets, obtained within the\nnon-linear Poisson-Boltzmann formalism, not only rationalizes the generic\nfeatures of the complex phase diagram of charged colloidal platelets such as\nGibbsite and Beidellite clays, but also predicts the existence of novel\nstructures. In addition, we find evidences of a strong slowing down of the\ndynamics upon increasing density."
    },
    {
        "anchor": "Spatially heterogeneous dynamics and locally arrested density\n  fluctuations from first-principles: We present a first-principles formalism for studying dynamical\nheterogeneities in glass forming liquids. Based on the Non-Equilibrium\nSelf-Consistent Generalized Langevin Equation theory, we were able to describe\nthe time-dependent local density profile during the particle interchange among\nsmall regions of the fluid. The final form of the diffusion equation contains\nboth, the contribution of the chemical potential gradient written in terms of a\ncoarse-grained density and a collective diffusion coefficient as well as the\neffect of a history-dependent mobility factor. With this diffusion equation we\ncaptured interesting phenomena in glass forming liquids such as the cases when\na strong density gradient is accompanied with a very low mobility factor\nattributable to the denser part: in such circumstances the density profile\nfalls into an arrested state even in the presence of a density gradient. On the\nother hand, we also show that above a certain critical temperature,which\ndepends on the volume fraction, any density heterogeneity relaxes to a uniform\nstate in a finite time, known as equilibration time. We further show that such\nequilibration time varies little with the temperature in diluted systems but\ncan change drastically with temperature in concentrated systems.",
        "positive": "Activity statistics in a colloidal glass former: experimental evidence\n  for a dynamical transition: In a dense colloidal suspension at a volume fraction slightly lower than that\nof its glass transition, we follow the trajectories of an assembly of tracers\nover a large time window. We define a local activity, which quantifies the\nlocal tendency of the system to rearrange. We determine the statistics of the\ntime and space integrated activity, and we argue that it develops a low\nactivity tail that comes on a par with the onset of glassy behavior and\nheterogeneous dynamics. These rare events may be interpreted as the reflection\nof an underlying dynamic phase transition."
    },
    {
        "anchor": "Membrane Stretching Elasticity of Lipid Vesicle and Thermal Shape\n  Fluctuations: One of the most widely used methods for determination of the bending\nelasticity modulus of model lipid membranes is the analysis of the shape\nfluctuations of nearly spherical lipid vesicles. The theoretical basis of this\nanalysis is given by Milner and Safran. In their theory the stretching effects\nare not considered. In the present study we generalized their approach\nincluding the stretching effects deduced after an application of statistical\nmechanics of vesicles.",
        "positive": "Manifestation of sub-Rouse modes in flow at the surface of low molecular\n  weight polystyrene: The presence of a viscoelastic mechanism distinctly different from the\nsegmental a-relaxation and the Rouse modes within the glass-rubber transition\nzone of polymers had been justified by theoretical considerations, and\nsubsequently experimentally verified in different bulk polymers by various\ntechniques, and in several laboratories. Referred to in the literature as the\nsub-Rouse modes, they were also found in polymer thin films by the creep\ncompliance measurements of McKenna and co-workers Established by experiment and\ntheoretical considerations is the enhanced mobility of sub-Rouse modes in thin\nPS films by the combination of effect from the free surface, finite size, and\ninduced chain orientations, concomitant with the segmental a-relaxation.\nInduced chain orientations effect is present only when h is less than the\nend-to-end distance of the high molecular weight polymer chains. In this paper,\nthe proven enhanced mobility of sub-Rouse modes at the surface of polymers is\nused to explain recent experimental investigations of viscous flow at the\nsurface of low molecular weight PS by Chai et al. [Science, 343, 994 (2014)],\nand by Yang et al. [Science, 328, 1676 (2010).]. Viscous flow of polymers is by\nglobal chain motion, therefore the observed large reduction of viscosity at the\nsurface of low molecular weight PS originates from the sub-Rouse modes, and not\nthe segmental a-relaxation. This distinction is not commonly recognized in the\ncurrent literature. The accerleration of the sub-Rouse modes at the surface\nexplains the experimental findings."
    },
    {
        "anchor": "Morpho-elastic model of the tortuous tumour vessels: Solid tumours have the ability to assemble their own vascular network for\noptimizing their access to the vital nutrients. These new capillaries are\nmorphologically different from normal physiological vessels. In particular,\nthey have a much higher spatial tortuosity forcing an impaired flow within the\nperitumoral area. This is a major obstacle for the efficient delivery of\nantitumoral drugs. This work proposes a morpho-elastic model of the tumour\nvessels. A tumour capillary is considered as a growing hyperelastic tube that\nis spatially constrained by a linear elastic environment, representing the\ninterstitial matter. We assume that the capillary is an incompressible\nneo-Hookean material, whose growth is modeled using a multiplicative\ndecomposition of the deformation gradient. We study the morphological stability\nof the capillary by means of the method of incremental deformations superposed\non finite strains, solving the corresponding incremental problem using the\nStroh formulation and the impedance matrix method. The incompatible axial\ngrowth of the straight capillary is found to control the onset of a bifurcation\ntowards a tortuous shape. The post-buckling morphology is studied using a mixed\nfinite element formulation in the fully nonlinear regime. The proposed model\nhighlights how the geometrical and the elastic properties of the capillary and\nthe surrounding medium concur to trigger the loss of marginal stability of the\nstraight capillary and the nonlinear development of its spatial tortuosity.",
        "positive": "Nonequilibrium patterns and shape fluctuations in reactive membranes: A simple kinetic model of a two-component deformable and reactive bilayer is\npresented. The two differently shaped components are interconverted by a\nnonequilibrium reaction, and a phenomenological coupling between local\ncomposition and curvature is proposed. When the two components are not\nmiscible, linear stability analysis predicts, and numerical simulations show,\nthe formation of stationary nonequilibrium composition/curvature patterns whose\ntypical size is determined by the reactive process. For miscible components, a\nlinearization of the dynamic equations is performed in order to evaluate the\ncorrelation function for shape fluctuations from which the behavior of these\nsystems in micropipet aspiration experiments can be predicted."
    },
    {
        "anchor": "Relative Resolution: A Hybrid Formalism for Fluid Mixtures: We show here that molecular resolution is inherently hybrid in terms of\nrelative separation: If molecules are close to each other, they must be\ncharacterized by a fine-grained (geometrically detailed) model, yet if\nmolecules are far from each other, they may be described by a coarse-grained\n(isotropically simplified) model. We notably present an analytical expression\nfor relating the two models by energy conservation. This hybrid framework is\ncorrespondingly capable of retrieving the structural and thermal behavior of\nvarious multi-component and multi-phase fluids across state space.",
        "positive": "Effective aspect ratio of helices in shear flow: We report the results of simulations of rigid colloidal helices suspended in\na shear flow, using dissipative particle dynamics for a coarse-grained\nrepresentation of the suspending fluid, as well as deterministic trajectories\nof non-Brownian helices calculated from the resistance tensor derived under the\nslender-body approximation. The shear flow produces nonuniform rotation of the\nhelices, similarly to other high aspect ratio particles, such that more\nelongated helices spend more time aligned with the fluid velocity. We introduce\na geometric effective aspect ratio calculated directly from the helix geometry\nand a dynamical effective aspect ratio derived from the trajectories of the\nparticles and find that the two effective aspect ratios are approximately equal\nover the entire parameter range tested. We also describe observed transient\ndeflections of the helical axis into the vorticity direction that can occur\nwhen the helix is rotating through the gradient direction and that depend on\nthe rotation of the helix about its axis."
    },
    {
        "anchor": "Measurement of Growing Dynamical Lengthscales and Prediction of the\n  Jamming Transition in a Granular Material: Supercooled liquids and dense colloids exhibit anomalous behaviour known as\n\"spatially heterogeneous dynamics\" (SHD), which becomes increasingly pronounced\nwith approach to the glass transition. Recently, SHD has been observed in\nconfined granular packings under slow shear near the onset of jamming,\nbolstering speculation that the two transitions are related. Here, we report\nmeasurements of SHD in a system of air-driven granular beads, as a function of\nboth density and effective temperature. On approach to jamming, the dynamics\nbecome progressively slower and more spatially heterogeneous. The rapid growth\nof dynamical time and length scales characterizing the heterogeneities can be\ndescribed both by mode-coupling theory and the Vogel-Tammann-Fulcher (VTF)\nequation, in analogy with glass-forming liquids. The value of the control\nvariable at the VTF transition coincides with point-J, the random close-packed\njamming density at which all motion ceases, indicating analogy with a zero\ntemperature ideal glass transition. Our findings demonstrate further\nuniversality of the jamming concept and provide a significant step forward in\nthe quest for a unified theory of jamming in disparate systems.",
        "positive": "Mapping micron-scale wetting properties of superhydrophobic surfaces: There is a huge interest in developing super-repellent surfaces for\nanti-fouling and heat transfer applications. To characterize the wetting\nproperties of such surfaces, the most common approach is to place a\nmillimetric-sized droplet and measure its contact angles. The adhesion and\nfriction forces can then be indirectly inferred from the Furmidge's relation.\nWhile easy to implement, contact angle measurements are semi-quantitative and\ncannot resolve wetting variations on a surface. Here, we attach a\nmicrometric-sized droplet to an Atomic Force Microscope cantilever to directly\nmeasure adhesion and friction forces with nanonewton force resolutions. We\nspatially map the micron-scale wetting properties of superhydrophobic surfaces\nand observe the time-resolved pinning-depinning dynamics as a droplet detaches\nfrom or moves across the surface."
    },
    {
        "anchor": "Ultracold Bose atoms in intense laser fields: intensity- and\n  density-dependent effects: Starting from the first principles of nonrelativistic QED we have derived the\nsystem of Maxwell-Schr\\\"odinger equations, which can be used for theoretical\ndescription of atom optical phenomena at high densities of atoms and high\nintensities of the laser radiation. The role of multiple atomic transitions\nbetween ground and excited states in atom optics has been investigated.\nNonlinear optical properties of interacting Bose gas are studied: formula for\nthe refractive index has been derived and the polariton spectrum of a\ncondensate interacting with an intense laser field has been investigated.",
        "positive": "Forces between chemically structured substrates mediated by critical\n  fluids: We consider binary liquid mixtures close to their critical points confined by\ntwo parallel, geometrically flat but chemically structured, substrates.\nUniversal order parameters profiles are calculated within mean field theory for\nperiodic patterns of stripes with alternating preferences for the two species\nof the mixture and with different relative positions of the two substrates.\n  From the order parameters profiles the effective forces between the two\nplates are derived. The tuning of Casimir amplitudes is discussed."
    },
    {
        "anchor": "Viscoelasticity and primitive path analysis of entangled polymer\n  liquids: From f-actin to polyethylene: We combine computer simulations and scaling arguments to develop a unified\nview of polymer entanglement based on the primitive path analysis (PPA) of the\nmicroscopic topological state. Our results agree with experimentally measured\nplateau moduli for three different polymer classes over a wide rangeof reduced\npolymer densities: (i) semi-dilute theta solutions of synthetic polymers, (ii)\nthe corresponding dense melts above the glass transition or crystallization\ntemperature, and (iii) solutions of semi-flexible (bio)polymers such as f-actin\nor suspensions of rodlike viruses. Together these systems cover the entire\nrange from loosely to tightly entangled polymers. In particular, we argue that\nthe primitive path analysis renormalizes a loosely to a tightly entangled\nsystem and provide a new explanation of the successful Lin-Noolandi packing\nconjecture for polymer melts.",
        "positive": "Quaternions and hybrid nematic disclinations: Disclination lines in nematic liquid crystals can exist in different\ngeometric conformations, characterised by their director profile. In certain\nconfined, colloidal and even more prominently in chiral nematics, the director\nprofile may vary along the disclination line. We construct a robust geometric\ndecomposition of director profile variations in closed disclination loops based\non a quaternion description and use it to apply topological classification to\nlinked loops with arbitrary variation of the profile. The description bridges\nthe gap between the known abstract classification scheme derived from homotopy\ntheory and the observable local features of disclinations. We compare the\nresulting decomposition of disclination loop features to a similar\ndecomposition of nematic textures on closed surfaces."
    },
    {
        "anchor": "Anomalous Diffusion of Symmetric and Asymmetric Active Colloids: The stochastic dynamics of colloidal particles with surface activity--in the\nform of catalytic reaction or particle release--and self-phoretic effects is\nstudied analytically. Three different time scales corresponding to inertial\neffects, solute redistribution, and rotational diffusion are identified and\nshown to lead to a plethora of different regimes involving inertial,\npropulsive, anomalous, and diffusive behaviors. For symmetric active colloids,\na regime is found where the mean-squared displacement has a super-diffusive\n$t^{3/2}$ behavior. At the longest time scales, an effective diffusion\ncoefficient is found which has a non-monotonic dependence on the size of the\ncolloid.",
        "positive": "Thermal and hydrodynamic effects in the ordering of lamellar fluids: Phase separation in a complex fluid with lamellar order has been studied in\nthe case of cold thermal fronts propagating diffusively from external walls.\nThe velocity hydrodynamic modes are taken into account by coupling the\nconvection-diffusion equation for the order parameter to a generalised\nNavier-Stokes equation. The dynamical equations are simulated by implementing a\nhybrid method based on a lattice Boltzmann algorithm coupled to finite\ndifference schemes. Simulations show that the ordering process occurs with\nmorphologies depending on the speed of the thermal fronts or, equivalently, on\nthe value of the thermal conductivity {\\xi}. At large value of {\\xi}, as in\ninstantaneous quenching, the system is frozen in entangled configurations at\nhigh viscosity while consists of grains with well ordered lamellae at low\nviscosity. By decreasing the value of {\\xi}, a regime with very ordered\nlamellae parallel to the thermal fronts is found. At very low values of {\\xi}\nthe preferred orientation is perpendicular to the walls in d = 2, while\nperpendicular order is lost moving far from the walls in d = 3."
    },
    {
        "anchor": "Capillary Condensation and Depinning Transitions in Open Slits: We study the low temperature phase equilibria of a fluid confined in an open\ncapillary slit formed by two parallel walls separated by a distance $L$ which\nare in contact with a reservoir of gas. The top wall of the capillary is of\nfinite length $H$ while the bottom wall is considered of macroscopic extent.\nThis system shows rich phase equilibria arising from the competition between\ntwo different types of capillary condensation, corner filling and meniscus\ndepinning transitions depending on the value of the aspect ratio $a=L/H$ and\ndivides into three regimes: For long capillaries, with $a<2/\\pi$, the\ncondensation is of type I involving menisci which are pinned at the top edges\nat the ends of the capillary. For intermediate capillaries, with $2/\\pi<a<1$,\ndepending on the value of the contact angle the condensation may be of type I\nor of type II, in which the menisci overspill into the reservoir and there is\nno pinning. For short capillaries, with $a>1$, condensation is always of type\nII. In all regimes, capillary condensation is completely suppressed for\nsufficiently large contact angles which is determined explicitly. For long and\nintermediate capillaries, we show that there is an additional continuous phase\ntransition in the condensed liquid-like phase, associated with the depinning of\neach meniscus as they round the upper open edges of the slit. Meniscus\ndepinning is third-order for complete wetting and second-order for partial\nwetting. Detailed scaling theories are developed for these transitions and\nphase boundaries which connect with the theories of wedge (corner) filling and\nwetting encompassing interfacial fluctuation effects and the direct influence\nof intermolecular forces.",
        "positive": "Tunable Dipolar Capillary Deformations for Magnetic Janus Particles at\n  Fluid-Fluid Interfaces: Janus particles have attracted significant interest as building blocks for\ncomplex materials in recent years. Furthermore, capillary interactions have\nbeen identified as a promising tool for directed self-assembly of particles at\nfluid-fluid interfaces. In this paper, we develop theoretical models describing\nthe behaviour of magnetic Janus particles adsorbed at fluid-fluid interfaces\ninteracting with an external magnetic field. Using numerical simulations, we\ntest the models predictions and show that the magnetic Janus particles deform\nthe interface in a dipolar manner. We suggest how to utilise the resulting\ndipolar capillary interactions to assemble particles at a fluid-fluid\ninterface, and further demonstrate that the strength of these interactions can\nbe tuned by altering the external field strength, opening up the possibility to\ncreate novel, reconfigurable materials."
    },
    {
        "anchor": "BiconeDrag - A data processing application for the oscillating conical\n  bob interfacial shear rheometer: BiconeDrag is a software package that allows one to perform a flow field\nbased data processing of dynamic interfacial rheology data pertaining to\nsurfactant laden air-fluid interfaces obtained by means of a rotational bicone\nshear rheometer. MATLAB and Python versions of the program are provided. The\nbicone fixture is widely used to transform a conventional bulk rotational\nrheometer into an interfacial shear rheometer. Typically, such systems are made\nof a bicone bob, which is mounted on the rheometer rotor, and a cylindrical\ncup. Usually, the experiment consists of measuring the response of the\ninterface under an oscillatory stress. The program takes the values of the\ntorque/angular displacement amplitude ratio and phase difference to compute the\ninterfacial dynamic moduli (or complex viscosity) by consistently taking into\naccount the hydrodynamic flow both at the interface and the subphase. This is\ndone by numerically solving the Navier-Stokes equations for the subphase\nvelocity field together with the Boussinesq-Scriven boundary condition at the\ninterface, and no slip boundary conditions elsewhere. Furthermore, the program\nimplements a new iterative scheme devised by solving for the complex Boussinesq\nnumber in the rotor's torque balance equation.",
        "positive": "Bending-induced director reorientation in a nematic liquid crystal\n  elastomer bonded to a hyperelastic substrate: In this paper, the two-dimensional pure bending of a hyperelastic substrate\ncoated by a nematic liquid crystal elastomer (abbreviated as NLCE) is studied\nwithin the framework of nonlinear elasticity. The governing system, arising\nfrom the deformational momentum balance, the orientational momentum balance and\nthe mechanical constraint, is formulated, and the corresponding exact solution\nis derived for a given constitutive model. It is found that there exist two\ndifferent bending solutions. In order to determine which the preferred one is,\nwe compare the total potential energy for both solutions and find that the two\nenergy curves may have an intersection point at a critical value of the bending\nangle $\\alpha_c$ for some material parameters. In particular, the director $\\bm\nn$ abruptly rotates $\\dfrac{\\pi}{2}$ from one solution to another at\n$\\alpha_c$, which indicates a director reorientation (or jump). Furthermore,\nthe effects of different material and geometric parameters on the bending\ndeformation and the transition angle $\\alpha_c$ can be revealed using the\nobtained bending solutions. Meanwhile, the exact solution can offer a benchmark\nproblem for validating the accuracy of approximated plate models for liquid\ncrystal elastomers."
    },
    {
        "anchor": "Membrane lateral structure: The influence of immobilized particles on\n  domain size: In experiments on model membranes, a formation of large domains of different\nlipid composition is readily observed. However, no such phase separation is\nobserved in the membranes of intact cells. Instead, a structure of small\ntransient inhomogeneities called lipid rafts are expected in these systems. One\nof the numerous attempts to explain small domains refers to the coupling of the\nmembrane to its surroundings, which leads to the immobilization of some of the\nmembrane molecules. These immobilized molecules then act as static obstacles\nfor the remaining mobile ones. We present detailed Molecular Dynamics\nsimulations demonstrating that this can indeed account for small domains. This\nconfirms previous Monte Carlo studies based on simplified models. Furthermore,\nby directly comparing domain structures obtained using Molecular Dynamics to\nMonte Carlo simulations of the Ising model, we demonstrate that domain\nformation in the presence of obstacles is remarkably insensitive to the details\nof the molecular interactions.",
        "positive": "Metastable and Unstable Cellular Solidification of Colloidal Suspensions: Colloidal particles are often seen as big atoms that can be directly observed\nin real space. They are therefore playing an increasingly important role as\nmodel systems to study processes of interest in condensed matter physics such\nas melting, freezing and glass transitions. The solidification of colloidal\nsuspensions has long been a puzzling phenomenon with many unexplained features.\nHere we demonstrate and rationalize the existence of instability and\nmetastability domains in cellular solidification of colloidal suspensions, by\ndirect in situ high-resolution X-ray radiography and tomography observations.\nWe explain such interface instabilities by a partial Brownian diffusion of the\nparticles leading to constitutional supercooling situations. Processing under\nunstable conditions leads to localized and global kinetic instabilities of the\nsolid/liquid interface, affecting the crystals morphology and particle\nredistribution behaviour."
    },
    {
        "anchor": "Vortex Nucleation in a Stirred Bose-Einstein Condensate: We studied the nucleation of vortices in a Bose-Einstein condensate stirred\nby a laser beam. We observed the vortex cores using time-of-flight absorption\nimaging. By varying the size of the stirrer, we observed either discrete\nresonances or a broad response as a function of the frequency of the stirrer's\nmotion. Stirring beams small compared to the condensate size generated vortices\nbelow the critical rotation frequency for the nucleation of surface modes,\nsuggesting a local mechanism of generation. In addition, we observed the\ncentrifugal distortion of the condensate due to the rotating vortex lattice and\nfound evidence for bent vortices.",
        "positive": "Mechanical response of active gels: We study a model of an active gel of cross-linked semiflexible filaments with\nadditional active linkers such as myosin II clusters. We show that the coupling\nof the elasticity of the semiflexible filaments to the mechanical properties of\nthe motors leads to contractile behavior of the gel, in qualitative agreement\nwith experimental observations. The motors, however, soften the zero frequency\nelastic constant of the gel. When the collective motor dynamics is incorporated\nin the model, a stiffening of the network at high frequencies is obtained. The\nfrequency controlling the crossover between low and high frequency network\nelasticity is estimated in terms of microscopic properties of motors and\nfilaments, and can be as low as 10^(-3)Hz."
    },
    {
        "anchor": "Mode Coupling of Phonons in a Dense One-Dimensional Microfluidic Crystal: Long-living coupled transverse and longitudinal phonon modes are explored in\ndense and regular arrangements of flat microfluidic droplets. The collective\noscillations are driven by hydrodynamic interactions between the confined\ndroplets and can be excited in a controlled way. Experimental results are\nquantitatively compared to simulation results obtained by multi-particle\ncollision dynamics. The observed transverse modes are acoustic phonons and can\nbe described by a linearized far-field theory, whereas the longitudinal modes\narise from a non-linear mode coupling due to the lateral variation of the flow\nfield under confinement.",
        "positive": "Explicit secular equations for piezoacoustic surface waves:\n  Shear-Horizontal modes: Attention is given to surface waves of shear-horizontal modes in\npiezoelectric crystals permitting the decoupling between an elastic in-plane\nRayleigh wave and a piezoacoustic anti-plane Bleustein-Gulyaev wave.\nSpecifically, the crystals possess $\\bar{4}$ symmetry (inclusive of\n$\\bar{4}2$m, $\\bar{4}3$m, and 23 classes) and the boundary is any plane\ncontaining the normal to a symmetry plane (rotated $Y$-cuts about the $Z$\naxis). The secular equation is obtained explicitly as a polynomial not only for\nthe metallized boundary condition but, in contrast to previous studies on the\nsubject, also for other types of boundary conditions. For the metallized\nsurface problem, the secular equation is a quadratic in the squared wave speed;\nfor the un-metallized surface problem, it is a sextic in the squared wave\nspeed; for the thin conducting boundary problem, it is of degree 16 in the\nspeed. The relevant root of the secular equation can be identified and the\ncomplete solution is then found (attenuation factors, field profiles, etc.).\nThe influences of the cut angle and of the conductance of the adjoining medium\nare illustrated numerically for GaAs ($\\bar{4}3$m), BaLaGa$_3$O$_7$\n($\\bar{4}2$m) and Bi$_{12}$GeO$_{20}$ (23). Indications are given on how to\napply the method to crystals with 222 symmetry."
    },
    {
        "anchor": "Shear banding in time-dependent flows of polymers and wormlike micelles: We study theoretically the formation of shear bands in time-dependent flows\nof polymeric and wormlike micellar surfactant fluids, focussing on the\nprotocols of step shear stress, step shear strain (or in practice a rapid\nstrain ramp), and shear startup, which are commonly studied experimentally. For\neach protocol we perform a linear stability analysis to provide a\nfluid-universal criterion for the onset of shear banding, following our recent\nLetter [Phys. Rev. Lett. 110 (2013) 086001]. In each case this criterion\ndepends only on the shape of the experimentally measured rheological response\nfunction for that protocol, independent of the constitutive properties of the\nmaterial in question. (Therefore our criteria in fact concern all complex\nfluids and not just the polymeric ones of interest here. A separate manuscript\n[in preparation] will explore them in a broad class of disordered soft glassy\nmaterials including foams, dense emulsions, dense colloids, and microgel bead\nsuspensions.) An important prediction is that pronounced banding can arise\ntransiently in each of these protocols, even in fluids for which the underlying\nconstitutive curve of stress as a function of strain-rate is monotonic and a\nsteadily flowing state is accordingly unbanded. For each protocol we provide\nnumerical results in the rolie-poly and Giesekus models that support our\npredictions. We comment on the ability of the rolie-poly model to capture the\nobserved experimental phenomenology, and on the failure of the Giesekus model.",
        "positive": "Detached topological charge on capillary bridges: We numerically investigate crystalline order on negative Gaussian curvature\ncapillary bridges. In agreement with the experimental results in [W. Irvine et\nal., Nature, \"Pleats in crystals on curved surfaces\", 2010, (468), 947]} we\nobserve for decreasing integrated Gaussian curvature a sequence of transitions,\nfrom no defects to isolated dislocations, pleats, scars and isolated sevenfold\ndisclinations. We especially focus on the dependency of the detached\ntopological charge on the integrated Gaussian curvature, for which we observe,\nagain in agreement with the experimental results, no net disclination for an\nintegrated curvature down to -10, and a linear behaviour from there on until\nthe disclinations match the integrated curvature of -12. The results are\nobtained using a phase field crystal approach on catenoid-like surfaces and are\nhighly sensitive to the initialization."
    },
    {
        "anchor": "Recent advances in the simulation of particle-laden flows: A substantial number of algorithms exists for the simulation of moving\nparticles suspended in fluids. However, finding the best method to address a\nparticular physical problem is often highly non-trivial and depends on the\nproperties of the particles and the involved fluid(s) together. In this report\nwe provide a short overview on a number of existing simulation methods and\nprovide two state of the art examples in more detail. In both cases, the\nparticles are described using a Discrete Element Method (DEM). The DEM solver\nis usually coupled to a fluid-solver, which can be classified as grid-based or\nmesh-free (one example for each is given). Fluid solvers feature different\nresolutions relative to the particle size and separation. First, a\nmulticomponent lattice Boltzmann algorithm (mesh-based and with rather fine\nresolution) is presented to study the behavior of particle stabilized fluid\ninterfaces and second, a Smoothed Particle Hydrodynamics implementation\n(mesh-free, meso-scale resolution, similar to the particle size) is introduced\nto highlight a new player in the field, which is expected to be particularly\nsuited for flows including free surfaces.",
        "positive": "Hydrodynamic and geometric effects in the sedimentation of model\n  run-and-tumble bacteria: The sedimentation process in a suspension of bacteria is the result of the\ncompetition between gravity and the intrinsic motion of the microorganisms. We\nperform simulations of run-and-tumble \"squirmers\" that move in a fluid medium,\nfocusing on the dependence of the non-equilibrium steady state on the bacterial\nswimming properties. We find that for high enough activity, the density\nprofiles are no longer simple exponentials; we recover the numerical results\nvia the introduction of a local effective temperature, suggesting that the\nbreakdown of the Perrin-like exponential form is a collective effect due to the\nonset of fluid-mediated dynamic correlations among particles. We show that\nanalogous concepts can fit also the case of shakers, for which we report the\nfirst study of this kind. Moreover we provide evidences of scenarios where the\nsolvent hydrodynamics induces nonlocal effects which require the fully\nthree-dimensional dynamics to be taken into account in order to understand\nsedimentation of active suspensions. Finally, analyzing the statistics of the\nbacterial swimming orientations, we discuss the emergence of polar order in the\nsteady state sedimentation profiles."
    },
    {
        "anchor": "Dynamics of Spontaneous Wrapping of Microparticles by Floppy Lipid\n  Membranes: Lipid membranes form the barrier between the inside and outside of cells and\nmany of their subcompartments. As such, they bind to a wide variety of nano-\nand micrometer sized objects and, in the presence of strong adhesive forces,\nstrongly deform and envelop particles. This wrapping plays a key role in many\nhealthy and disease-related processes. So far, little work has focused on the\ndynamics of the wrapping process. Here, using a model system of micron-sized\ncolloidal particles and giant unilamellar lipid vesicles with tunable adhesive\nforces, we measure the velocity of the particle during its wrapping process as\nwell as the forces exerted on it by the lipid membrane. Dissipation at the\ncontact line appears to be the main factor determining the wrapping velocity\nand time to wrap an object.",
        "positive": "Compact interaction potential for van der Waals nanorods: We studied the van der Waals interactions of two finite, solid, cylindrical\nrods at arbitrary angle and position with respect to each other. An analytic\ninterpolative formula for the interaction potential energy is constructed,\nbased on various asymptotic cases. The potential can be readily used for\nnumerical and analytic description of multi-wall carbon nanotubes, metallic\nnanorods, rod-shaped colloids, or any other similar objects with significant\nvan der Waals interactions."
    },
    {
        "anchor": "Reshaping of a Janus ring: We consider reshaping of closed Janus filaments acquiring intrinsic curvature\nupon actuation of an active component -- a nematic elastomer elongating upon\nphase transition. Linear stability analysis establishes instability thresholds\nof circles with no imposed twist, dependent on the ratio $q$ of the intrinsic\ncurvature to the inverse radius of the original circle. Twisted circles are\nproven to be absolutely unstable but the linear analysis well predicts the\ndependence of the looping number of the emerging configurations on the imposed\ntwist. Modeling stable configurations by relaxing numerically the overall\nelastic energy detects multiple stable and metastable states with different\nlooping numbers. The bifurcation of untwisted circles turns out to be\nsubcritical, so that nonplanar shapes with a lower energy exist at $q$ below\nthe critical value. The looping number of stable shapes generally increases\nwith $q$.",
        "positive": "Macroscopic electrostatic potentials and interactions in self-assembled\n  molecular bilayers: the case of Newton black films: We propose a very simple but 'realistic' model of amphiphilic bilayers,simple\nenough to be able to include a large number of molecules in the sample, but\nnevertheless detailed enough to include molecular charge distributions,\nflexible amphiphilic molecules and a reliable model of water. All these\nparameters are essential in a nanoscopic scale study of intermolecular and long\nrange electrostatic interactions. We also propose a novel, simple and more\naccurate macroscopic electrostatic field for model bilayers. This model goes\nbeyond the total dipole moment of the sample, which on a time average is zero\nfor this type of symmetrical samples, i. e., it includes higher order moments\nof this macroscopic electric field. We show that by representing it with a\nsuperposition of gaussians it can be 'analytically' integrated, and therefore\nits calculation is easily implemented in a MD simulation (even in simulations\nof non-symmetrical bi- or multi-layers). In this paper we test our model by\nmolecular dynamics simulations of Newton black films."
    },
    {
        "anchor": "Aqueous Laponite Dispersions are Attractive Gels, Not Repulsive Wigner\n  Glasses: A Critical Commentary: An aqueous dispersion of Laponite has been studied in the literature for over\nthe past three decades. Typically, the aqueous dispersion of Laponite undergoes\nincessant evolution of its microstructure, wherein its elastic modulus and the\nmean relaxation time show a continuous increase as a function of time. A\nconsiderable amount of discussion has revolved around the nature of this\ndispersion, specifically whether it can be classified as a repulsive Wigner\nglass state, characterized by disconnected Laponite particles stabilized by\nelectrostatic repulsions, or an attractive gel state, in which the particles\nform a percolated space-spanning network. The proponents of the Wigner glass\nstate also conjecture that this system experiences a glass-glass transition\nafter a period of two days has elapsed since its preparation. In this\ncommentary, we explore this topic from a rheological point of view analyzing\nthe published literature and performing new experiments. Aided by additional\nevidence from the literature, we propose that rheological behavior\noverwhelmingly suggests that an aqueous dispersion of Laponite undergoes sol -\nattractive gel transition and remains in the attractive gel state over at least\nup to 7 days without undergoing any additional transition. Importantly,\nrheology, despite being a macroscopic tool governed by principles of mechanics,\noffers profound insight into the microstructure of this particular system. The\ncorresponding analysis conclusively determines the state of an aqueous\ndispersion of Laponite to be an attractive gel.",
        "positive": "Sliding Dynamics for Bubble Phases on Periodic Modulated Substrates: We analyze a bubble forming system composed of particles with competing long\nrange repulsive and short range attractive interactions driven over a\nquasi-one-dimensional periodic substrate. We find various pinned and sliding\nphases as a function of substrate strength and drive amplitude. When the\nsubstrate is weak, a pinned bubble phase appears that depins elastically into a\nsliding bubble lattice. For stronger substrates, we find anisotropic bubbles,\ndisordered bubbles, and stripe phases. Plastic depinning occurs via the hopping\nof individual particles from one bubble to the next in a pinned bubble lattice,\nand as the drive increases, there is a transition to a state where all of the\nbubbles are moving but are continuously shedding and absorbing individual\nparticles. This is followed at high drives by a moving bubble lattice in which\nthe particles can no longer escape their individual bubbles. The transition\nbetween the plastic and elastic sliding phases can be detected via signatures\nin the velocity-force curves, differential conductivity, and noise. When the\nbubbles shrink due to an increase in the attractive interaction term, they fit\nbetter inside the pinning troughs and become more strongly pinned, leading to a\nreentrant pinning phase. For weaker attractive terms, the size of the bubbles\nbecomes greater than the width of the pinning troughs and the depinning becomes\nelastic with a reduced depinning threshold."
    },
    {
        "anchor": "Clustering and flocking of repulsive chiral active particles with\n  non-reciprocal couplings: Recently, non-reciprocal systems have become a focus of growing interest.\nExamples occur in soft and active matter, but also in engineered quantum\nmaterials and neural (brain) networks. Here, we investigate the impact of\nnon-reciprocity on the collective behavior of a system of (dry) chiral active\nmatter. Specifically, we consider a mixture of \"circle swimmers\" with steric\ninteractions and non-reciprocal alignment couplings. Based on hydrodynamic\nequations which we derive from a set of Langevin equations, we explore the\ninterplay of non-reciprocity, finite size, and chirality. We first consider, as\na reference, one-species systems with reciprocal couplings. Based on a linear\nstability analysis and numerical simulations, we here observe three different\ntypes of collective behavior, that is, flocking, motility-induced phase\nseparation, and a combination of both. Turning then to a non-reciprocal system,\nwe find that non-reciprocity can turn otherwise stationary instabilities into\noscillatory ones, affect the relative orientation of flocks, and, crucially,\nchange the general type of instability. This illustrates the drastic impact of\nnon-reciprocity and chirality on the emergent collective dynamics of active\nmatter systems, with potentially far-reaching biological implications.",
        "positive": "Methods for Creation and Linear Elastic Response Analysis of Packings of\n  Semi-flexible Soft Polymer Chains: From understanding the sand on the beach to the foam on your beer, soft\nsphere simulations have been crucial to the study of the amorphous world around\nus. However, many of the materials we interact with on a daily basis aren't\ncomprised of individual grains, but complex molecules and chains of polymers.\nBy extending the soft sphere model to a model of linked spheres, we can learn\nmore about the materials we interact with on a daily basis. In this methods\npaper, I show how one can find and study the physical properties of packings of\nflexible chains, rigid molecules, and everything in between. In addition to\ndescribing the energy landscape of these materials, these methods describe how\nto shear stabilize polymer packings, classify them in the jamming hierarchy,\ndescribe their elastic properties, and much more. This simple modification to\nsoft sphere simulations has the potential to yield new discoveries surrounding\nglasses."
    },
    {
        "anchor": "Hydrodynamic Instabilities Provide A Generic Route To Spontaneous\n  Biomimetic Oscillations In Chemomechanically Active Filaments: Non-equilibrium processes which convert chemical energy into mechanical\nmotion enable the motility of organisms. Bundles of inextensible filaments\ndriven by energy transduction of molecular motors form essential components of\nmicron-scale motility engines like cilia and flagella. The mimicry of\ncilia-like motion in recent experiments on synthetic active filaments supports\nthe idea that generic physical mechanisms may be sufficient to generate such\nmotion. Here we show, theoretically, that the competition between the\ndestabilising effect of hydrodynamic interactions induced by force-free and\ntorque-free chemomechanically active flows, and the stabilising effect of\nnonlinear elasticity, provides a generic route to spontaneous oscillations in\nactive filaments. These oscillations, reminiscent of prokaryotic and eukaryotic\nflagellar motion, are obtained without having to invoke structural complexity\nor biochemical regulation. This minimality implies that biomimetic\noscillations, previously observed only in complex bundles of active filaments,\ncan be replicated in simple chains of generic chemomechanically active beads.",
        "positive": "Weak Segregation Theory and Non-Conventional Morphologies in the Ternary\n  ABC Triblock Copolymers: The Leibler weak segregation theory in molten diblock copolymers is\ngeneralized with due regard for the 2nd shell harmonics contributions defined\nin the paper and the phase diagrams are built for the linear and miktoarm\nternary ABC triblock copolymers. The symmetric linear copolymers with the\nmiddle block non-selective with respect to the side ones are shown to undergo\nthe continuous ODT not only into the lamellar phase but also into various\nnon-conventional cubic phases (depending on the middle block composition it\ncould be the simple cubic, face-centered cubic or non-centrosymmetric phase\nrevealing the symmetry of space group No.214 first predicted to appear in\nmolten block copolymers). For asymmetric linear ABC copolymers a region of\ncompositions is found where the weakly segregated gyroid (double gyroid) phase\nexists between the planar hexagonal and lamellar or one of the non-conventional\ncubic phases up to the very critical point. In contrast, the miktoarm ABC block\ncopolymers with one of its arm non-selective with respect to the two others are\nshown to reveal a pronounced tendency towards strong segregation, which is\npreceded by increase of stability of the conventional BCC phase and a peculiar\nweakly segregated BCC phase (BCC3), where the dominant harmonics belong to the\n3rd co-ordination sphere of the reciprocal lattice. The validity region of the\ndeveloped theory is discussed and outlined in the composition triangles both\nfor linear and miktoarm copolymers."
    },
    {
        "anchor": "Valence can control the nonexponential viscoelastic relaxation of\n  multivalent reversible gels: Gels made of telechelic polymers connected by reversible crosslinkers are a\nversatile design platform for biocompatible viscoelastic materials. Their\nlinear response to a step strain displays a fast, near-exponential relaxation\nwhen using low valence crosslinkers, while larger supramolecular crosslinkers\nbring about much slower dynamics involving a wide distribution of time scales\nwhose physical origin is still debated. Here, we propose a model where the\nrelaxation of polymer gels in the dilute regime originates from elementary\nevents in which the bonds connecting two neighboring crosslinkers all\ndisconnect. Larger crosslinkers allow for a greater average number of bonds\nconnecting them, but also generate more heterogeneity. We characterize the\nresulting distribution of relaxation time scales analytically, and accurately\nreproduce stress relaxation measurements on metal-coordinated hydrogels with a\nvariety of crosslinker sizes including ions, metal-organic cages, and\nnanoparticles. Our approach is simple enough to be extended to any crosslinker\nsize and could thus be harnessed for the rational design of complex\nviscoelastic materials.",
        "positive": "Entropy-induced separation of star polymers in porous media: We present a quantitative picture of the separation of star polymers in a\nsolution where part of the volume is influenced by a porous medium. To this\nend, we study the impact of long-range-correlated quenched disorder on the\nentropy and scaling properties of $f$-arm star polymers in a good solvent. We\nassume that the disorder is correlated on the polymer length scale with a\npower-law decay of the pair correlation function $g(r) \\sim r^{-a}$. Applying\nthe field-theoretical renormalization group approach we show in a double\nexpansion in $\\epsilon=4-d$ and $\\delta=4-a$ that there is a range of\ncorrelation strengths $\\delta$ for which the disorder changes the scaling\nbehavior of star polymers. In a second approach we calculate for fixed space\ndimension $d=3$ and different values of the correlation parameter $a$ the\ncorresponding scaling exponents $\\gamma_f$ that govern entropic effects. We\nfind that $\\gamma_f-1$, the deviation of $\\gamma_f$ from its mean field value\nis amplified by the disorder once we increase $\\delta$ beyond a threshold. The\nconsequences for a solution of diluted chain and star polymers of equal\nmolecular weight inside a porous medium are: star polymers exert a higher\nosmotic pressure than chain polymers and in general higher branched star\npolymers are expelled more strongly from the correlated porous medium.\nSurprisingly, polymer chains will prefer a stronger correlated medium to a less\nor uncorrelated medium of the same density while the opposite is the case for\nstar polymers."
    },
    {
        "anchor": "Controlling chaos: Periodic defect braiding in active nematics confined\n  to a cardioid: This work examines self-mixing in active nematics, a class of fluids in which\nmobile topological defects drive chaotic flows in a system comprised of\nbiological filaments and molecular motors. We present experiments that\ndemonstrate how geometrical confinement can influence the braiding dynamics of\nthe defects. Notably, we show that confinement in cardioid-shaped wells leads\nto realization of the golden braid, a maximally efficient mixing state of\nexactly three defects with no defect creation or annihilation. We characterize\nthe golden braid state using different measures of topological entropy and the\nLyapunov exponent. In particular, topological entropy measured from the\nstretching rate of material lines agrees well with an analytical computation\nfrom braid theory. Increasing the size of the confining cardioid produces a\ntransition from the golden braid, to the fully chaotic active turbulent state.",
        "positive": "Buckling instability for a charged and fluctuating semiflexible polymer: In this article we address the problem of Euler's buckling instability in a\ncharged semi-flexible polymer that is under the action of a compressive force.\nWe consider this instability as a phase transition and investigate the role of\nthermal fluctuations in the buckling critical force. By performing molecular\ndynamic simulations, we show that the critical force decreases when the\ntemperature increases. Repulsive electrostatic interaction in the finite\ntemperature is in competition with thermal fluctuations to increase the\nbuckling threshold."
    },
    {
        "anchor": "A minimizing principle for the Poisson-Boltzmann equation: The Poisson-Boltzmann equation is often presented via a variational\nformulation based on the electrostatic potential. However, the functional has\nthe defect of being non-convex. It can not be used as a local minimization\nprinciple while coupled to other dynamic degrees of freedom. We formulate a\nconvex dual functional which is numerically equivalent at its minimum and which\nis more suited to local optimization.",
        "positive": "Reentrant transition in the shear viscosity of dilute rigid rod\n  dispersions: The intrinsic viscosity of a dilute dispersion of rigid rods is studied using\na recently developed direct numerical simulation (DNS) method for particle\ndispersions. A reentrant transition from shear-thinning to the 2nd Newtonian\nregime is successfully reproduced in the present DNS results around a Peclet\nnumber ${\\rm Pe}=150$, which is in good agreement with our theoretical\nprediction of ${\\rm Pe}=143$, at which the dynamical crossover from Brownian to\nnon-Brownian behavior takes place in the rotational motion of the rotating rod.\nThe viscosity undershoot is observed in our simulations before reaching the 2nd\nNewtonian regime. The physical mechanisms behind these behaviors are analyzed\nin detail."
    },
    {
        "anchor": "Effective extensional-torsional elasticity and dynamics of helical\n  filaments under distributed loads: We study slender, helical elastic rods subject to distributed forces and\nmoments. Focussing on the case when the helix axis remains straight, we employ\nthe method of multiple scales to systematically derive an 'effective-column'\ntheory from the Kirchhoff rod equations: the helical filament is described as a\nnaturally-straight rod (aligned with the helix axis) for which the extensional\nand torsional deformations are coupled. Importantly, our analysis is\nasymptotically exact in the limit of a 'highly-coiled' filament (i.e., when the\nhelical wavelength is much smaller than the characteristic lengthscale over\nwhich the filament bends due to external loading) and is able to account for\nlarge, unsteady displacements. In the small-deformation limit, we exactly\nrecover the coupled wave equations used to describe the free vibrations of\nhelical coil springs, thereby justifying previous effective-column\napproximations in which linearised stiffness coefficients are assumed to apply\nlocally and dynamically. We then illustrate our theory with two loading\nscenarios: (I) a heavy helical rod deforming under its own weight; and (II) the\ndynamics of axial rotation (twirling) in viscous fluid, which may be considered\nas a simple model for a bacteria flagellar filament. More broadly, our analysis\nprovides a framework to develop reduced models of helical rods in a wide\nvariety of physical and biological settings, and yields analytical insight into\ntheir elastic instabilities. In particular, our analysis indicates that tensile\ninstabilities are a generic phenomenon when helical rods are subject to a\ncombination of distributed forces and moments.",
        "positive": "Noisy nonlinear dynamics of vesicles in flow: We present a model for the dynamics of fluid vesicles in linear flow which\nconsistently includes thermal fluctuations and nonlinear coupling between\ndifferent modes. At the transition between tank-treading and tumbling, we\npredict a trembling motion which is at odds with the known deterministic\nmotions and for which thermal noise is strongly amplified. In particular,\nhighly asymmetric shapes are observed even though the deterministic flow only\nallows for axisymmetric ones. Our results explain quantitatively recent\nexperimental observations [Levant and Steinberg, Phys. Rev. Lett. 109, 268103\n(2012)]."
    },
    {
        "anchor": "On opening crack propagation in viscoelastic solids: We show that the Persson-Brener theory of crack propagation in viscoelastic\nsolids gives a viscoelastic fracture energy factor $G/G_0 = 1+f$ which is\nnearly the same as the viscoelastic factor obtained using the cohesive-zone\nmodel. We also discuss finite-size effects and comment on the use of crack\npropagation theories for \"solids\" with a viscoelastic modulus that vanishes at\nzero frequency.",
        "positive": "Deflection of phototactic microswimmers through obstacle arrays: We study the effect of inhomogeneous environments on the swimming direction\nof the microalgae \\textit{Chlamydomonas Reinhardtii} (CR) in the presence of a\nlight stimulus. Positive or negative phototaxis describe the ability of\nmicroorganisms to bias their swimming towards or away from a light source. Here\nwe consider microswimmers with negative phototaxis in a microfluidic device\nwith a microfabricated square lattice of pillars as obstacles. We measured a\nmean deflection of microswimmers that shows an interesting nonlinear dependence\non the direction of the guiding light beam with respect to the symmetry axes of\nthe pillar lattice. By simulating a model swimmer in a pillar lattice and\nanalyzing its scattering behavior, we identified the width of the reorientation\ndistribution of swimmers to be also crucial for the nonlinear behavior of the\nswimmer deflection. On the basis of these results we suggest in addition an\nanalytical model for microswimmers, where the pillar lattice is replaced by an\nanisotropic scattering medium, that depends only on a scattering rate and the\nwidth of the reorientation distribution of swimmers. This flexible and handy\nmodel fits the experimental results as well. The presented analysis of the\ndeflection of light guided swimmers through pillar lattice may be used for\nseparating swimmers having different reorientation distributions."
    },
    {
        "anchor": "Towards a liquid-state theory for active matter: In equilibrium, the collective behaviour of particles interacting via steep,\nshort-ranged potentials is well captured by the virial expansion of the free\nenergy at low density. Here, we extend this approach beyond equilibrium to the\ncase of active matter with self-propelled particles. Given that active systems\ndo not admit any free-energy description in general, our aim is to build the\ndynamics of the coarse-grained density from first principles without any\nequilibrium assumption. Starting from microscopic equations of motion, we\nobtain the hierarchy of density correlations, which we close with an ansatz for\nthe two-point density valid in the dilute regime at small activity. This\nclosure yields the nonlinear dynamics of the one-point density, with\nhydrodynamic coefficients depending explicitly on microscopic interactions, by\nanalogy with the equilibrium virial expansion. This dynamics admits a spinodal\ninstability for purely repulsive interactions, a signature of motility-induced\nphase separation. Therefore, although our approach should be restricted to\ndilute, weakly-active systems a priori, it actually captures the features of a\nbroader class of active matter.",
        "positive": "Dynamical design of spatial patterns of colloidal suspensions: We study the collective dynamics of colloidal suspensions in the presence of\na time-dependent potential, by means of dynamical density functional theory. We\nconsider a non-linear diffusion equation for the density and show that spatial\npatterns emerge from a sinusoidal external potential with a time-dependent\nwavelength. These patterns are characterized by a sinusoidal density with the\naverage wavelength and a Bessel-function envelope with an induced wavelength\nthat depends only on the amplitude of the temporal oscillations. As a\ngeneralization of this result, we propose a design strategy to obtain a family\nof spatial patterns using time-dependent potentials of practically arbitrary\nshape."
    },
    {
        "anchor": "Biasing the ferronematic - a new way to detect weak magnetic field: Magnetic properties of a ferronematic, i.e., nematic liquid crystal doped\nwith magnetic nanoparticles in low volume concentration are studied, with the\nfocus on the ac magnetic susceptibility. A weak dc bias magnetic field (units\nof Oe) applied to the ferronematic in its isotropic phase increases the ac\nmagnetic susceptibility considerably. Passage of the isotropic-to-nematic phase\ntransition resets this enhancement irreversibly (unless the dc bias field is\napplied again in the isotropic phase). These experimental findings pave a way\nto application possibilities, such as low magnetic field sensors, or basic\nlogical elements for information storage.",
        "positive": "Monte Carlo simulations of liquid crystals near rough walls: The effect of surface roughness on the structure of liquid crystalline fluids\nnear solid substrates is studied by Monte Carlo simulations. The liquid crystal\nis modelled as a fluid of soft ellipsoidal molecules and the substrate is\nmodelled as a hard wall that excludes the centres of mass of the fluid\nmolecules. Surface roughness is introduced by embedding a number of molecules\nwith random positions and orientations within the wall. It is found that the\ndensity and order near the wall are reduced as the wall becomes rougher (i.e.\nthe number of embedded molecules is increased). Anchoring coefficients are\ndetermined from fluctuations in the reciprocal space order tensor. It is found\nthat the anchoring strength decreases with increasing surface roughness."
    },
    {
        "anchor": "Geometry and physics in the deformations of crystalline caps: Elucidating the interplay of stress and geometry is a fundamental scientific\nquestion arising in multiple fields. In this work, we investigate the geometric\nfrustration of crystalline caps confined on the sphere in both elastic and\nplastic regimes. Based on the revealed quasi-conformal ordering, we discover\nthe partial, but uniform screening of the substrate curvature by the induced\ncurvature underlying the inhomogeneous lattice. This scenario is fundamentally\ndifferent from the conventional screening mechanism based on topological\ndefects. In the plastic regime, the yield of highly stressed caps leads to\nfractures with featured morphologies not found in planar systems. We also\ndemonstrate the strategy of engineering stress and fractures by vacancies.\nThese results advance our general understanding on the organization and\nadaptivity of geometrically-frustrated crystalline order.",
        "positive": "Reconfigurable knots and links in chiral nematic colloids: Tying knots and linking microscopic loops of polymers, macromolecules, or\ndefect lines in complex materials is a challenging task for material\nscientists. We demonstrate the knotting of microscopic topological defect lines\nin chiral nematic liquid crystal colloids into knots and links of arbitrary\ncomplexity by using laser tweezers as a micromanipulation tool. All knots and\nlinks with up to six crossings, including the Hopf link, the Star of David and\nthe Borromean rings are demonstrated, stabilizing colloidal particles into an\nunusual soft matter. The knots in chiral nematic colloids are classified by the\nquantized self-linking number, a direct measure of the geometric, or Berry's,\nphase. Forming arbitrary microscopic knots and links in chiral nematic colloids\nis a demonstration of how relevant the topology can be for the material\nengineering of soft matter."
    },
    {
        "anchor": "Rheological response of a glass-forming liquid having large bidispersity: Using extensive numerical simulations, we investigate the flow behaviour of a\nmodel glass-forming binary mixture whose constituent particles have a large\nsize ratio. The rheological response to applied shear is studied in the regime\nwhere the larger species are spatially predominant. We demonstrate that the\nmacroscopic rigidity that emerges with increasing density occurs in the regime\nwhere the larger species undergo a glass transition while the smaller species\ncontinue to be highly diffusive. We analyse the interplay between the timescale\nimposed by the shear and the quiescent relaxation dynamics of the two species\nto provide a microscopic insight into the observed rheological response.\nFinally, by tuning the composition of the mixture, we illustrate that the\nsystematic insertion of the smaller particles affects the rheology by lowering\nof viscosity of the system.",
        "positive": "Controlling Marangoni induced instabilities in spin-cast polymer films:\n  how to prepare uniform films: In both research and industrial settings spin coating is extensively used to\nprepare highly uniform thin polymer films. However, under certain conditions,\nspin coating results in films with non-uniform surface morphologies. Although\nthe spin coating process has been extensively studied, the origin of these\nmorphologies is not fully understood and the formation of non-uniform spincast\nfilms remains a practical problem. Here we report on experiments demonstrating\nthat the formation of surface instabilities during spin coating is dependent on\ntemperature. Our results suggest that non-uniform spincast films form as a\nresult of the Marangoni effect, which describes flow due to surface tension\ngradients. We find that both the wavelength and amplitude of the pattern\nincrease with temperature. Finally, and most important from a practical\nviewpoint, the non-uniformities in the film thickness can be entirely avoided\nsimply by lowering the spin coating temperature."
    },
    {
        "anchor": "Localization in musical steelpans: The steelpan is a pitched percussion instrument that takes the form of a\nconcave bowl with several localized dimpled regions of varying curvature. Each\nof these localized zones, called notes, can vibrate independently when struck,\nand produces a sustained tone of a well-defined pitch. While the association of\nthe localized zones with individual notes has long been known and exploited,\nthe relationship between the shell geometry and the strength of the mode\nconfinement remains unclear. Here, we explore the spectral properties of the\nsteelpan modeled as a vibrating elastic shell. To characterize the resulting\neigenvalue problem, we generalize a recently developed theory of localization\nlandscapes for scalar elliptic operators to the vector-valued case, and predict\nthe location of confined eigenmodes by solving a Poisson problem. A finite\nelement discretization of the shell shows that the localization strength is\ndetermined by the difference in curvature between the note and the surrounding\nbowl. In addition to providing an explanation for how a steelpan operates as a\ntwo-dimensional xylophone, our study provides a geometric principle for\ndesigning localized modes in elastic shells.",
        "positive": "Dynamics of microdroplets over the surface of hot water: When drinking a cup of coffee under the morning sunshine, you may notice\nwhite membranes of steam floating on the surface of the hot water. They stay\nnotably close to the surface and appear to almost stick to it. Although the\nmembranes whiffle because of the air flow of rising steam, peculiarly fast\nsplitting events occasionally occur. They resemble cracking to open slits\napproximately 1 mm wide in the membranes, and leave curious patterns. We\nstudied this phenomenon using a microscope with a high-speed video camera and\nfound intriguing details: i) the white membranes consist of fairly\nmonodispersed small droplets of the order of 10 $\\mu\\,{\\rm m}$; ii) they\nlevitate above the water surface by 10$\\sim$100 $\\mu{\\rm m}$; iii) the\nsplitting events are a collective disappearance of the droplets, which\npropagates as a wave front of the surface wave with a speed of 1$\\sim$2 m/s;\nand iv) these events are triggered by a surface disturbance, which results from\nthe disappearance of a single droplet."
    },
    {
        "anchor": "Packing loops into annular cavities: The continuous packing of a flexible rod in two-dimensional cavities yields a\ncountable set of interacting domains that resembles non-equilibrium cellular\nsystems and belongs to a new class of light-weight material. However, the link\nbetween the length of the rod and the number of domains requires investigation\nespecially in the case of non-simply connected cavities, where the number of\navoided regions emulates an effective topological temperature. In the present\narticle we report the results of an experiment of injection of a single\nflexible rod into annular cavities in order to find the total length needed to\ninsert a given number of loops (domains of one vertex). Using an exponential\nmodel to describe the experimental data we quite minutely analyze the initial\nconditions, the intermediary behavior, and the tight-packing limit. This method\nallows the observation of a new fluctuation phenomenon associated with\ninstabilities in the dynamic evolution of the packing process. Furthermore, the\nfractal dimension of the global pattern enters the discussion under a novel\npoint of view. A comparison with the classical problems of the random close\npacking of disks, and jammed disk packings is made.",
        "positive": "Flow of power-law fluids in self-affine fracture channels: The two-dimensional pressure driven flow of non-Newtonian power-law fluids in\nself-affine fracture channels at finite Reynolds number is calculated. The\nchannels have constant mean aperture and two values $\\zeta$=0.5 and 0.8 of the\nHurst exponent are considered. The calculation is based on the\nlattice-Boltzmann method, using a novel method to obtain a power-law variation\nin viscosity, and the behavior of shear-thinning, Newtonian and\nshear-thickening liquids is compared. Local aspects of the flow fields, such as\nmaximum velocity and pressure fluctuations, were studied, and the non-Newtonian\nfluids were compared to the (previously-studied) Newtonian case. The\npermeability results may be collapsed into a master curve of friction factor\nvs. Reynolds number using a scaling similar to that employed for porous media\nflow, and exhibits a transition from a linear regime to a more rapid variation\nat Re increases."
    },
    {
        "anchor": "A single-particle energy-conserving dissipative particle dynamics\n  approach for simulating thermophoresis of nanoparticles in polymer networks: Thermophoresis is an effective method to drive the motion of nanoparticles in\nfluids. The transport of nanoparticles in polymer networks has significant\nfundamental and applied importance in biology and medicine, and can be\ndescribed as Brownian particles crossing entropic barriers. This study proposes\na novel extension of dissipative particle dynamics (DPD), called the\nsingle-particle energy-conserving dissipative particle dynamics (seDPD), which\ncombines the features of single-particle dissipative particle dynamics (sDPD)\nand energy-conserving dissipative particle dynamics (eDPD) to simulate the\nthermophoresis of nanoparticles under temperature gradients. The reliability of\nthe seDPD method is verified by considering the viscosity, thermal diffusivity,\nand hydrodynamic drag force on the nanoparticles. Using this method, the\ntransport of nanoparticles driven by the thermophoretic force across the\npolymer network is simulated. The results show that the nanoparticles exhibit\nthe phenomenon of giant acceleration of diffusion (GAD) in the polymer network,\nindicating that Brownian particles can exhibit GAD when crossing entropic\nbarriers.",
        "positive": "Exploring Thixotropic Timescale: Phenomenological Insights and\n  Analytical Perspectives: Thixotropy is characterized by an increase in viscosity when a material is\nsubjected to no flow (quiescent) or weak flow conditions and a decrease in\nviscosity when it is subjected to strong flow conditions. The characteristic\ntimescale associated with the thixotropic phenomenon, particularly how the\nviscosity increases with time, has been termed the thixotropic timescale. In\nthe literature, several approaches have been suggested for estimating the\nthixotropic timescale. The most prominent approach, however, infers it from a\nspecific form of a kinetic expression for structure parameter evolution. In\nthis paper, we study the various kinds of structural kinetic models, and by\ncarrying out a careful analysis of the same, we propose a parameter for the\nthixotropic timescale that is associated with the most generic form of the\nkinetic expression for structure parameter evolution. We observe that when the\nviscosity of the structural kinetic model undergoes continuous increase with\ntime and eventually diverges under quiescent conditions, which we believe is\nthe most practical scenario, our analysis suggests that increasing the\nthixotropic timescale weakens the thixotropic character of a system. We also\npropose a new phenomenological measure of the thixotropic timescale: ${{\\tau\n}_{thix}}={{\\left( d\\text{ln}\\eta /dt \\right)}^{-1}}$, where $\\eta $ is\nviscosity and $t$ is time. The proposed definition allows a straightforward and\nunique way to determine thixotropic timescale through experiments and agrees\nwell with the conventional notion of thixotropy."
    },
    {
        "anchor": "Optomechanical Properties of Stretched Polymer Dispersed Liquid Crystal\n  Films for Scattering Polarizer Applications: A scattering polarizer is created by subjecting a polymer dispersed liquid\ncrystal (PDLC) film to tensile strain. The optomechanical properties of the\nfilm are investigated by simultaneously measuring the stress-strain and\npolarization dependent optical transmission characteristics. The correlation\nbetween transmittances of two orthogonal polarizations and the stress-strain\ncurve reveals that the polymer orientation as well as the droplet shape\nanisotropy influences the liquid crystal alignment within the droplets. A\nMonte-Carlo simulation based on the Lebwohl-Lasher model is used to explain the\nsubtle influence of polymer orientation on liquid crystal alignment.",
        "positive": "Local structure of liquid carbon controls diamond nucleation: Diamonds melt at temperatures above 4000 K. There are no measurements of the\nsteady-state rate of the reverse process: diamond nucleation from the melt,\nbecause experiments are difficult at these extreme temperatures and pressures.\nUsing numerical simulations, we estimate the diamond nucleation rate and find\nthat it increases by many orders of magnitude when the pressure is increased at\nconstant supersaturation. The reason is that an increase in pressure changes\nthe local coordination of carbon atoms from three-fold to four-fold. It turns\nout to be much easier to nucleate diamond in a four-fold coordinated liquid\nthan in a liquid with three-fold coordination, because in the latter case the\nfree-energy cost to create a diamond-liquid interface is higher. We speculate\nthat this mechanism for nucleation control is relevant for crystallization in\nmany network-forming liquids. On the basis of our calculations, we conclude\nthat homogeneous diamond nucleation is likely in carbon-rich stars and unlikely\nin gaseous planets."
    },
    {
        "anchor": "Direct Observation of the Translational Immobilization of Water\n  Molecules Under Nanoscale Confinement: Here, Overhauser Dynamic Nuclear Polarization (ODNP) analyzes the\ntranslational dynamics of water confined inside reverse micelles (RMs). It\noffers a unique insight into the translational diffusion of water inside RMs,\nin particular measuring the diffusion in a \"RM-fixed\" frame, rather than\nrelative to the laboratory frame. This study seeks to confirm whether or not\nthe act of tuning the size of the RMs, which can be achieved simply by\nadjusting the \"water loading\" ($w_0$, i.e., the mole ratio of surfactant to\nwater) offer a near-continuous tuning of the translational diffusion of water.\nThe results here confirm this supposition, while offering two additional\ninteresting observations (1) surprisingly, translational diffusion slows to a\nnear-stop for RMs that are small, but that still contain hundreds of water\nmolecules in their core and (2) even relatively large RMs exhibit translational\ndynamics in their core (center) that is only as fast as translational dynamics\non the surface of a lipid bilayer; extrapolation to larger sized water pools\nimplies the need for tens of thousands of water molecules present in a confined\npool in order to recover bulk-like translational dynamics. The parts of this\nstudy that take place at the lowest water loadings represent the first known\ninstance of an ODNP measurement where the probing spin label interacts\ncontinuously with a full complement of water molecules (as opposed to sitting\nburied inside a lipid membrane or protein core), and yet clearly observes only\nslow translational diffusion of water. The particular system here, with an\nNMR-silent CCl$_4$ dispersant, shoud prove easy to reproduce. Thus, this study\nalso opens up the pathway to future measurements where RMs serve as a ruler for\ndynamics, in particular for smaller resonance frequencies that can ostensibly\ndetect the dynamics of the slower water inside severely confined (i.e., small)\nRMs.",
        "positive": "Memory capacity of adaptive flow networks: Biological flow networks adapt their network morphology to optimise flow\nwhile being exposed to external stimuli from different spatial locations in\ntheir environment. These adaptive flow networks retain a memory of the stimulus\nlocation in the network morphology. Yet, what limits this memory and how many\nstimuli can be stored is unknown. Here, we study a numerical model of adaptive\nflow networks by applying multiple stimuli subsequently. We find strong memory\nsignals for stimuli imprinted for a long time into young networks.\nConsequently, networks can store many stimuli for intermediate stimulus\nduration, which balance imprinting and ageing."
    },
    {
        "anchor": "Shear-thickening of dense bidispersed suspensions: We study the rheological behaviour of a dense bidispersed suspension varying\nthe relative size of the two dispersed phases. The main outcome of our analysis\nis that an enhanced flowability (reduced relative viscosity) of the suspension\ncan be achieved by increasing the dispersion ratio of the phases. We explain\nthe observed result by showing that the presence of large particles increases\nthe packing efficiency of the suspension, leading to a reduction of the\ncontribution of the contacts on the overall viscosity of the suspension in the\nshear-thickening regime, i.e. where the contacts are the dominating component.",
        "positive": "Granular discharge and clogging for tilted hoppers: We measure the flux of spherical glass beads through a hole as a systematic\nfunction of both tilt angle and hole diameter, for two different size beads.\nThe discharge increases with hole diameter in accord with the Beverloo relation\nfor both horizontal and vertical holes, but in the latter case with a larger\nsmall-hole cutoff. For large holes the flux decreases linearly in cosine of the\ntilt angle, vanishing smoothly somewhat below the angle of repose. For small\nholes it vanishes abruptly at a smaller angle. The conditions for zero flux are\ndiscussed in the context of a {\\it clogging phase diagram} of flow state vs\ntilt angle and ratio of hole to grain size."
    },
    {
        "anchor": "A second order thermodynamic perturbation theory for hydrogen bond\n  cooperativity in water: It has been extensively demonstrated through first principles quantum\nmechanics calculations that water exhibits strong hydrogen bond cooperativity.\nClassical molecular simulation and statistical mechanics methods typically\nassume pairwise additivity, meaning they cannot account for these 3-body and\nhigher cooperative effects. In this document, we extend second order\nthermodynamic perturbation theory to correct for hydrogen bond cooperativity in\n4 site water. We show that the association theory gives substantially different\npredictions than the first order result, which does not include hydrogen bond\ncooperativity. By comparison to spectroscopy, neutron diffraction and molecular\nsimulation data, we show that the theory accurately predicts the hydrogen\nbonding structure of water as a function of temperature and density.",
        "positive": "A giant overshoot effect in the Janssen granular column: We present new experimental results on the mechanical behavior of static\ngranular assemblies confined in a vertical column. Our measurements confirm,\nfor the first time, the universal Janssen's scaling for the stress saturation\ncurve. We show consequently, in the context of isotropic elasticity, a relation\nbetween the Poisson ratio and granular packing fraction. Moreover, using a\nsystematic study of the overshoot effect created by a top mass equal to the\nsaturation mass, we show behaviors reproduced qualitatively by isotropic\nelastic materials but in the case of a granular assembly of a spectacular\namplitude. These experimental results are strong tests for any theory of\ngranular matter."
    },
    {
        "anchor": "Hydrodynamic modes in dense trapped ultracold gases: We consider the hydrodynamic modes for dense trapped ultracold gases, where\nthe interparticle distance is comparable to the scattering length. We show that\nthe experimental determination of the hydrodynamic mode frequencies allows to\nobtain quite directly the equation of state of a dense gas. As an example we\ninvestigate the case of two equal fermionic populations in different hyperfine\nstates with attractive interaction and in particular the vicinity of the\ncollapse.",
        "positive": "Water dynamics: Relation between hydrogen bond bifurcations, molecular\n  jumps, local density & hydrophobicity: Structure and dynamics of water remain a challenge. Resolving the properties\nof hydrogen bonding lies at the heart of this puzzle. Here we employ ab initio\nMolecular Dynamics (AIMD) simulations over a wide temperature range. The total\nsimulation time was approx 2 ns. Both bulk water and water in the presence of a\nsmall hydrophobic molecule were simulated. We show that large-angle jumps and\nbond bifurcations are fundamental properties of water dynamics and that they\nare intimately coupled to both local density and hydrogen bond stretch\noscillations in scales from about 60 to a few hundred femtoseconds: Local\ndensity differences are the driving force for bond bifurcations and the\nconsequent large-angle jumps. The jumps are intimately connected to the\nrecently predicted energy asymmetry. Our analysis also appears to confirm the\nexistence of the so-called negativity track provided by the lone pairs of\nelectrons on the oxygen atom to enable water rotation."
    },
    {
        "anchor": "Phase behaviour of attractive and repulsive ramp fluids: integral\n  equation and computer simulation studies: Using computer simulations and a thermodynamically self consistent integral\nequation we investigate the phase behaviour and thermodynamic anomalies of a\nfluid composed of spherical particles interacting via a two-scale ramp\npotential (a hard core plus a repulsive and an attractive ramp) and the\ncorresponding purely repulsive model. Both simulation and integral equation\nresults predict a liquid-liquid de-mixing when attractive forces are present,\nin addition to a gas-liquid transition. Furthermore, a fluid-solid transition\nemerges in the neighbourhood of the liquid-liquid transition region, leading to\na phase diagram with a somewhat complicated topology. This solidification at\nmoderate densities is also present in the repulsive ramp fluid, thus preventing\nfluid-fluid separation.",
        "positive": "Water diffusion in carbon nanotubes under directional electric fields:\n  Coupling between mobility and hydrogen bonding: We have investigated the diffusion and structure of TIP4P/2005 water confined\nin carbon nanotubes subjected to external electric fields. A wide range of\ndiameters has been used to show a highly size-dependent behavior of the water\ndiffusion. We also found that the diffusion is extremely affected by the\nintensity of the applied field. However, is the relative direction between the\nfield and the tube axis that causes the most intriguing behavior. Electric\nfields forming angles of $0^{\\circ}$ and $45^{\\circ}$ with the tube axis were\nfound to slow down the water dynamics by increasing organization, while fields\nperpendicular to the tube axis can enhance water diffusion in some cases by\ndecreasing the hydrogen bond formation. Remarkably, for the 1.2 nm diameter\nlong (9,9) nanotube, the field along the tube axis melts the water structure\nincreasing the water mobility. These results points out that the structure and\ndynamics of confined water are extremely sensitive to external fields and\nsuggest the use of electric fields as a facilitator for filtration processes."
    },
    {
        "anchor": "OpTiDDM (Optical Tweezers integrating Differential Dynamic Microscopy)\n  maps the spatiotemporal propagation of nonlinear stresses in polymer blends\n  and composites: How local stresses propagate through polymeric fluids, and, more generally,\nhow macromolecular dynamics give rise to viscoelasticity are open questions\nvital to wide-ranging scientific and industrial fields. Here, to unambiguously\nconnect polymer dynamics to force response, and map stress propagation in\nmacromolecular materials, we present a powerful approach-Optical Tweezers\nintegrating Differential Dynamic Microscopy (OpTiDMM)-that simultaneously\nimposes local strains, measures resistive forces, and analyzes the motion of\nthe surrounding polymers. Our measurements with blends of ring and linear\npolymers (DNA) and their composites with stiff polymers (microtubules) uncover\na surprising resonant response, in which affine alignment, superdiffusivity,\nand elastic memory are maximized when the strain rate is comparable to the\nentanglement rate. Microtubules suppress this resonance, while substantially\nincreasing elastic force and memory, due to varying degrees to which the\npolymers buildup, stretch and flow along the strain path, and configurationally\ndissipate stress. More broadly, the rich multi-scale coupling of mechanics and\ndynamics afforded by OpTiDDM, empowers its interdisciplinary use to elucidate\nnon-trivial phenomena that sculpt stress propagation dynamics-critical to\ncommercial applications and cell mechanics alike.",
        "positive": "Rubber friction on (apparently) smooth lubricated surfaces: We study rubber sliding friction on hard lubricated surfaces. We show that\neven if the hard surface appears smooth to the naked eye, it may exhibit short\nwavelength roughness, which may give the dominant contribution to rubber\nfriction. That is, the observed sliding friction is mainly due to the\nviscoelastic deformations of the rubber by the substrate surface asperities.\nThe presented results are of great importance for rubber sealing and other\nrubber applications involving (apparently) smooth surfaces."
    },
    {
        "anchor": "Collective excitations of a two-dimensional interacting Bose gas in\n  anti-trap and linear external potentials: We present a method of finding approximate analytical solutions for the\nspectra and eigenvectors of collective modes in a two-dimensional system of\ninteracting bosons subjected to a linear external potential or the potential of\na special form $u(x,y)=\\mu -u \\cosh^2 x/l$, where $\\mu$ is the chemical\npotential. The eigenvalue problem is solved analytically for an artificial\nmodel allowing the unbounded density of the particles. The spectra of\ncollective modes are calculated numerically for the stripe, the rare density\nvalley and the edge geometry and compared with the analytical results. It is\nshown that the energies of the modes localized at the rare density region and\nat the edge are well approximated by the analytical expressions. We discuss\nBose-Einstein condensation (BEC) in the systems under investigations at $T\\ne\n0$ and find that in case of a finite number of the particles the regime of BEC\ncan be realized, whereas the condensate disappears in the thermodynamic limit.",
        "positive": "Evaluating the Friction of Rotary Joints in Molecular Machines: A computationally-efficient method for evaluating friction in molecular\nrotary bearings is presented. This method estimates drag from fluctuations in\nmolecular dynamics simulations via the fluctuation-dissipation theorem. This is\neffective even for simulation times short compared to a bearing's energy\ndamping time and for rotation speeds comparable to or below typical thermal\nvalues. We apply this method to two molecular rotary bearings of similar size\nat 300K: previously studied nested (9,9)/(14,14) double-walled carbon nanotubes\nand a hypothetical rotary joint consisting of single acetylenic bonds in a\nrigid diamondoid housing. The acetylenic joint has a rotational frictional drag\ncoefficient of $2 \\times 10^{-35}\\,\\mbox{kg m${}^2$/s}$. The friction for the\nnested nanotubes is 120 times larger, comparable to values reported by previous\nstudies. This fluctuation-based method could evaluate dissipation in a variety\nof molecular systems with similarly rigid and symmetric bearings."
    },
    {
        "anchor": "Hysteresis loop area scaling exponents in DNA unzipping by a periodic\n  force: A Langevin dynamics simulation study: Using Langevin dynamics simulations, we study the hysteresis in unzipping of\nlonger double stranded DNA chains whose ends are subjected to a time dependent\nperiodic force with frequency $\\omega$ and amplitude $G$ keeping the other end\nfixed. We find that the area of the hysteresis loop, $A_{loop}$, scales as\n$1/\\omega$ at higher frequencies, whereas it scales as\n$(G-G_c)^{\\alpha}\\omega^{\\beta}$ with exponents $\\alpha=1$ and $\\beta=1.25$ in\nthe low frequency regime. These values are same as the exponents obtained in\nMonte Carlo simulation studies of a directed self avoiding walk model of a\nhomopolymer DNA [R. Kapri, Phys. Rev. E 90, 062719 (2014)], and the block\ncopolymer DNA [R. K. Yadav and R. Kapri, Phys. Rev. E 103, 012413 (2021)] on a\nsquare lattice, and differs from the values reported earlier using Langevin\ndynamics simulation studies on a much shorter DNA hairpins.",
        "positive": "Weak and Strong Coupling Theories for Polarizable Colloids and\n  Nano-Particles: A theory is presented which allows us to accurately calculate the density\nprofile of monovalent and multivalent counterions in suspensions of polarizable\ncolloids or nano-particles. In the case of monovalent ions, we derive a\nweak-coupling theory that explicitly accounts for the ion-image interaction,\nleading to a modified Poisson-Boltzmann equation. For suspensions with\nmultivalent counterions, a strong-coupling theory is used to calculate the\ndensity profile near the colloidal surface and a Poisson-Boltzmann equation\nwith a renormalized boundary condition to account for the counterion\ndistribution in the far-field. All the results are compared with the Monte\nCarlo simulations, showing an excellent agreement between the theory and the\nsimulations."
    },
    {
        "anchor": "Generic Stress Rectification in Nonlinear Elastic Media: Stress propagation in nonlinear media is crucial in cell biology, where\nmolecular motors exert anisotropic force dipoles on the fibrous cytoskeleton.\nWhile the force dipoles can be either contractile or expansile, a medium made\nof fibers which buckle under compression rectifies these stresses towards a\nbiologically crucial contraction. A general understanding of this rectification\nphenomenon as a function of the medium's elasticity is however lacking. Here we\nuse theoretical continuum elasticity to show that rectification is actually a\nvery general effect in nonlinear materials subjected to anisotropic internal\nstresses. We analytically show that both bucklable and constitutively linear\nmaterials subjected to geometrical nonlinearities rectify small forces towards\ncontraction, while granular-like materials rectify towards expansion. Using\nsimulations, we moreover show that these results extend to larger forces.\nBeyond fiber networks, these results could shed light on the propagation of\nstresses in brittle or granular materials following a local plastic\nrearrangement.",
        "positive": "Simulations of Crystal Nucleation from Solution at Constant Chemical\n  Potential: A widely spread method of crystal preparation is to precipitate it from a\nsupersaturated solution. In such a process, control of solution concentration\nis of paramount importance. Nucleation process, polymorph selection, and\ncrystal habits depend crucially on this thermodynamic parameter. When\nperforming simulations in the canonical ensemble as the crystalline phase is\ndeposited the solution is depleted of solutes. This unavoidable modification of\nthe thermodynamic conditions leads to significant artifact. Here we adopt the\nidea of the constant chemical potential molecular dynamics approach of Perego\net al. [J. Chem. Phys. 2015, 142, 144113] to the study of nucleation. Our\nmethod allows determining the crystal nucleus size and nucleation rates at\nconstant supersaturation. As an example we study the homogeneous nucleation of\nsodium chloride from its supersaturated aqueous solution."
    },
    {
        "anchor": "On the Formation of Hydrogen Peroxide in Water Microdroplets: Recent reports on the formation of hydrogen peroxide (H$_2$O$_2$) in water\nmicrodroplets produced via pneumatic spraying or capillary condensation have\ngarnered significant attention. How covalent bonds in water could break under\nsuch conditions challenges our textbook understanding of physical chemistry and\nthe water substance. While there is no definitive answer, it has been\nspeculated that ultrahigh electric fields at the air-water interface are\nresponsible for this chemical transformation. Here, we resolve this mystery via\na comprehensive experimental investigation of H$_2$O$_2$ formation in (i) water\nmicrodroplets sprayed over a range of liquid flow-rates, the (shearing) air\nflow rates, and the air composition (ii) water microdroplets condensed on\nhydrophobic substrates formed via hot water or humidifier under controlled air\ncomposition. Specifically, we assessed the contributions of the evaporative\nconcentration and shock waves in sprays and the effects of trace O$_3$(g) on\nthe H$_2$O$_2$ formation. Glovebox experiments revealed that the H$_2$O$_2$\nformation in water microdroplets was most sensitive to the air-borne ozone\n(O$_3$) concentration. In the absence of O$_3$(g), we could not detect\nH$_2$O$_2$(aq) in sprays or condensates (detection limit: 250 nM. In contrast,\nmicrodroplets exposed to atmospherically relevant O$_3$(g) concentration\n(10-100 ppb) formed 2-30 $\\mu$M H$_2$O$_2$(aq); increasing the gas-liquid\nsurface area, mixing, and contact duration increased H$_2$O$_2$(aq)\nconcentration. Thus, the mystery is resolved - the water surface facilitates\nthe O$_3$(g) mass transfer, which is followed by the chemical transformation of\nO$_3$(aq) into H$_2$O$_2$(aq). These findings should also help us understand\nthe implications of this chemistry in natural and applied contexts.",
        "positive": "Self-organized magnetic particles to tune the mechanical behaviour of a\n  granular system: Above a certain density a granular material jams. This property can be\ncontrolled by either tuning a global property, such as the packing fraction or\nby applying shear strain, or at the micro-scale by tuning grain shape,\ninter-particle friction or externally controlled organization. Here, we\nintroduce a novel way to change a local granular property by adding a weak\nanisotropic magnetic interaction between particles. We measure the evolution of\nthe pressure, $P$, and coordination number, $Z$, for a packing of 2D\nphoto-elastic disks, subject to uniaxial compression. Some of the particles\nhave embedded cuboidal magnets. The strength of the magnetic interactions\nbetween particles are too weak to have a strong direct effect on $P$ or $Z$\nwhen the system is jammed. However, the magnetic interactions play an important\nrole in the evolution of latent force networks when systems containing a large\nenough fraction of the particles with magnets are driven through unjammed\nstates. In this case, a statistically stable network of magnetic chains\nself-organizes and overlaps with force chains, strengthening the granular\nmedium. We believe this property can be used to reversibly control mechanical\nproperties of granular materials."
    },
    {
        "anchor": "Instabilities and waves in thin films of living fluids: We formulate the thin-film hydrodynamics of a suspension of polar self-driven\nparticles and show that it is prone to several instabilities through the\ninterplay of activity, polarity and the existence of a free surface. Our\napproach extends, to self-propelling systems, the work of Ben Amar and Cummings\n[Phys Fluids 13 (2001) 1160] on thin-film nematics. Based on our estimates the\ninstabilities should be seen in bacterial suspensions and the lamellipodium,\nand are potentially relevant to the morphology of biofilms. We suggest several\nexperimental tests of our theory.",
        "positive": "Linear and Nonlinear Rheology and Structural Relaxation in Dense Glassy\n  and Jammed Soft Repulsive Microgel Suspensions: We present an integrated experimental and quantitative theoretical study of\nthe mechanics of self-crosslinked, neutral, repulsive pNIPAM microgel\nsuspensions over concentration (c) range spanning the fluid, glassy and\nputative \"soft jammed\" regimes. In the glassy regime we measure a linear\nelastic dynamic shear modulus over 3 decades which follows an apparent power\nlaw concentration dependence G'~$c^{5.64}$, followed by a sharp crossover to a\nnearly linear growth at high concentrations. We formulate a theoretical\napproach to address all three regimes within a single conceptual Brownian\ndynamics framework. A minimalist single particle description is constructed\nthat allows microgel size to vary with concentration due to steric de-swelling\neffects. Using a Hertzian repulsion interparticle potential and a suite of\nstatistical mechanical theories, quantitative predictions under quiescent\nconditions of microgel collective structure, dynamic localization length,\nelastic modulus, and the structural relaxation time are made. Based on a\nconstant inter-particle repulsion strength parameter which is determined by\nrequiring the theory to reproduce the linear elastic shear modulus over the\nentire concentration regime, we demonstrate good agreement between theory and\nexperiment. Theoretical predictions of how quiescent structural relaxation time\nchanges under deformation, and how the yield stress and strain change as a\nfunction of concentration has been made. Reasonable agreement with our\nobservations is obtained. To the best of our knowledge, this is the first\nattempt to quantitatively understand structure, quiescent relaxation and shear\nelasticity, and nonlinear yielding of dense microgel suspensions using\nmicroscopic force based theoretical methods that include activated hopping\nprocesses. We expect our approach will be useful for other soft polymeric\nparticle suspensions in the core-shell family."
    },
    {
        "anchor": "Role of minimum adhesive wear particle size in third-body layer\n  properties: We employ a novel discrete element method (DEM) force formulation to simulate\nadhesive wear and assess the effects of material and loading parameters on the\nproperties of the third-body layer (TBL) formed during sliding motion. The\nstudy emphasizes the role of a material's critical length scale d* in the\nrheology of the TBL. This critical length scale is already known for\ncontrolling the size of smallest wear particles. We observe the emergence of a\nseveral wear regimes involving wear particle creation and aggregation, with\nlimited effect from d* on TBL properties. Instead, material strength and\nsurface energy have a profound influence. This study opens up new avenues for\nexploration of larger systems, three-dimensional setups, and other loading\nconditions.",
        "positive": "Light-induced dynamics of liquid-crystalline droplets on the surface of\n  iron-doped lithium niobate crystals: We investigated the effect of a photovoltaic field generated on the surface\nof iron-doped lithium niobate crystals on droplets of a ferroelectric nematic\nliquid crystalline and a standard nematic liquid crystalline material deposited\non this surface. When such assembly is illuminated with a laser beam, a wide\nrange of dynamic phenomena are initiated. Droplets located outside the laser\nspot are dragged in the direction of the illuminated area, while droplets\nlocated inside the illuminated region tend to bridge each other and rearrange\ninto tendril-like structures. In the ferroelectric nematic phase (NF) these\nprocesses take place via the formation of conical spikes evolving into jet\nstreams, similar to the behavior of droplets of conventional dielectric liquids\nexposed to overcritical electric fields. However, in contrast to conventional\nliquids, the jet streams of the NF phase exhibit profound branching. In the\nnematic phase (N) of both the ferroelectric nematic and the standard nematic\nmaterial, dynamic processes occur via smooth-edged continuous features typical\nfor conventional liquids subjected to under-critical fields. The difference in\ndynamic behavior is attributed to the large increase of dielectric permittivity\nin the ferroelectric nematic phase with respect to the dielectric permittivity\nof the nematic phase."
    },
    {
        "anchor": "Vesicle budding induced by binding of curvature-inducing proteins: Vesicle budding induced by protein binding that generates an isotropic\nspontaneous curvature is studied using a mean-field theory. Many spherical buds\nare formed via protein binding. As the binding chemical potential increases,\nthe proteins first bind to the buds and then to the remainder of the vesicle.\nFor a high spontaneous curvature and/or high bending rigidity of the bound\nmembrane, it is found that a first-order transition occurs between a small\nnumber of large buds and a large number of small buds. These two states coexist\naround the transition point. The proposed scheme is simple and easily\napplicable to many interaction types, so we investigate the effects of\ninter-protein interactions, the protein-insertion-induced changes in area, the\nvariation of the saddle-splay-modulus, and the area-difference-elasticity\nenergy. The differences in the preferred curvatures for curvature sensing and\ngeneration are also clarified.",
        "positive": "Influence of polymer excluded volume on the phase behavior of\n  colloid-polymer mixtures: We determine the depletion-induced phase-behavior of hard sphere colloids and\ninteracting polymers by large-scale Monte Carlo simulations using very accurate\ncoarse-graining techniques. A comparison with standard Asakura-Oosawa model\ntheories and simulations shows that including excluded volume interactions\nbetween polymers leads to qualitative differences in the phase diagrams. These\neffects become increasingly important for larger relative polymer size. Our\nsimulations results agree quantitatively with recent experiments."
    },
    {
        "anchor": "Long-ranged velocity correlations in dense systems of self-propelled\n  particles: Model systems of self-propelled particles reproduce many phenomena observed\nin laboratory active matter systems that defy our thermal equilibrium-based\nintuition. In particular, in stationary states of self-propelled systems, it is\nrecognized that velocities of different particles exhibit non-trivial\nequal-time correlations. Such correlations are absent in equivalent equilibrium\nsystems. Recently, researchers found that the range of the velocity\ncorrelations increases with increasing persistence time of the self-propulsion\nand can extend over many particle diameters. Here we review the initial studies\nof long-ranged velocity correlations in solid-like systems of self-propelled\nparticles. Then, we demonstrate that the long-ranged velocity correlations are\nalso present in dense fluid-like systems. We show that the range of velocity\ncorrelations in dense systems of self-propelled particles is determined by the\ncombination of the self-propulsion and the virial bulk modulus that originates\nfrom repulsive interparticle interactions.",
        "positive": "Shear Thickening and Scaling of the Elastic Modulus in a Fractal\n  Colloidal System with Attractive Interactions: Dilute oil dispersions of fractal carbon black particles with attractive Van\nder Waals interactions display continuous shear thickening followed by shear\nthinning at high shear rates. The shear thickening transition occurs at\n$\\dot\\gamma_{c}\\approx 10^{2}-10^{3}s^{-1}$ and is driven by hydrodynamic\nbreakup of clusters. Pre-shearing dispersions at shear rates\n$\\dot\\gamma>\\dot\\gamma_{c}$ produces enhanced-modulus gels where $G' \\sim\n\\sigma_{pre-shear}^{1.5-2}$ and is directly proportional to the residual stress\nin the gel measured at a fixed sample age. The observed data can be accounted\nfor using a simple scaling model for the breakup of fractal clusters under\nshear stress."
    },
    {
        "anchor": "Molecular Dynamics Simulations of Water Anchored in Multi-Layered\n  Nanoporous MoS$_2$ Membranes: Implications for Desalination: One of the most promising applications in nanoscience is the design of new\nmaterials to improve water permeability and selectivity of nanoporous\nmembranes. Understanding the molecular architecture behind these fascinating\nstructures and how it impacts the water flow is an intricate but necessary\ntask. We studied here, the water flux through multi-layered nanoporous\nmolybdenum disulfide (MLNMoS$_2$) membranes with different nanopore sizes and\nlength. Molecular dynamics simulations show that the permeability do not\nincrease with the inverse of the membrane thickness, violating the classical\nhydrodynamic behavior. The data also reveals that the water dynamics is slower\nthan that observed in frictionless carbon nanotubes and multi-layer graphene\nmembranes, which we explain in terms of an anchor mechanism observed in between\nlayers. We show that the membrane permeability is critically dependent on the\nnanopore architecture, bringing important insights into the manufacture of new\ndesalination membranes.",
        "positive": "Finite-Bandwidth Calculations for Charge Carrier Mobility in Organic\n  Crystals: Finite-bandwidth effects on the temperature dependence of the mobility of\ninjected carriers in pure organic crystals are explored for a simplifed case of\nimpurity scattering. Temperature-dependent bandwidth effects are discussed\nbriefly through a simplified combination of band and polaronic concepts."
    },
    {
        "anchor": "Friction-induced Shear thickening: a microscopic perspective: We develop a microscopic picture of shear thickening in dense suspensions\nwhich emphasizes the role of frictional forces, coupling rotational and\ntranslational degrees of freedom. Simulations with contact forces and viscous\ndrag only, reveal pronounced shear thickening with a simultaneous increase in\ncontact number and energy dissipation by frictional forces. At high densities,\nwhen the translational motion is severely constrained, we observe liquid-like\ngear-states with pronounced relative rotations of the particles coexisting with\nsolid-like regions which rotate as a whole. The latter are stabilised by\nfrustrated loops which become more numerous and persistent with increasing\npressure, giving rise to an increasing lengthscale of this mosaique-like\nstructure and a corresponding increase in viscosity.",
        "positive": "Topological symmetry breaking in viscous coarsening: The crucial role of hydrodynamic pinch-off instabilities is evidenced in the\ncoarsening stage of viscous liquids. The phase separation of a barium\nborosilicate glass melt is studied by in-situ synchrotron X-Ray tomography at\nhigh temperature. The high viscosity contrast between the less viscous phase\nand the more viscous phase induces a topological symmetry breaking: capillary\nbreakups occur preferentially in the less viscous phase. As a result,\ncontrasting morphologies are obtained in the two phases. This symmetry breaking\nis illustrated on three different glass compositions , corresponding to\ndifferent volume fractions of the two phases. In particular, a fragmentation\nphenomenon, reminiscent of the end-pinching mechanism proposed by Stone et al.\n[1, 2] is evidenced in the less viscous phase."
    },
    {
        "anchor": "Kinetics of Loop Formation in Polymer Chains: We investigate the kinetics of loop formation in flexible ideal polymer\nchains (Rouse model), and polymers in good and poor solvents. We show for the\nRouse model, using a modification of the theory of Szabo, Schulten, and\nSchulten, that the time scale for cyclization is $\\tau_c\\sim \\tau_0 N^2$ (where\n$\\tau_0$ is a microscopic time scale and $N$ is the number of monomers),\nprovided the coupling between the relaxation dynamics of the end-to-end vector\nand the looping dynamics is taken into account. The resulting analytic\nexpression fits the simulation results accurately when $a$, the capture radius\nfor contact formation, exceeds $b$, the average distance between two connected\nbeads. Simulations also show that, when $a < b$, $\\tau_c\\sim N^{\\alpha_\\tau}$,\nwhere $1.5<{\\alpha_\\tau}\\le 2$ in the range $7<N<200$ used in the simulations.\nBy using a diffusion coefficient that is dependent on the length scales $a$ and\n$b$ (with $a<b$), which captures the two-stage mechanism by which looping\noccurs when $a < b$, we obtain an analytic expression for $\\tau_c$ that fits\nthe simulation results well. The kinetics of contact formation between the ends\nof the chain are profoundly affected when interactions between monomers are\ntaken into account. Remarkably, for $N < 100$ the values of $\\tau_c$ decrease\nby more than two orders of magnitude when the solvent quality changes from good\nto poor. Fits of the simulation data for $\\tau_c$ to a power law in $N$\n($\\tau_c\\sim N^{\\alpha_\\tau}$) show that $\\alpha_\\tau$ varies from about 2.4 in\na good solvent to about 1.0 in poor solvents. Loop formation in poor solvents,\nin which the polymer adopts dense, compact globular conformations, occurs by a\nreptation-like mechanism of the ends of the chain.",
        "positive": "Investigation of cyclic liquefaction with discrete element simulations: A discrete-element method (DEM) assembly of virtual particles is calibrated\nto approximate the behavior of a natural sand in undrained loading. The\nparticles are octahedral, bumpy clusters of spheres that are compacted into\nassemblies of different densities. The contact model is a Jager generalization\nof the Hertz contact, which yields a small-strain shear modulus that is\nproportional to the square root of confining stress. Simulations made of\ntriaxial extension and compression loading conditions and of simple shear\nproduce behaviors that are similar to sand. Undrained cyclic shearing\nsimulations are performed with nonuniform amplitudes of shearing pulses and\nwith 24 irregular seismic shearing sequences. A methodology is proposed for\nquantifying the severities of such irregular shearing records, allowing the 24\nsequences to be ranked in severity. The relative severities of the 24 seismic\nsequences show an anomalous dependence on sampling density. Four scalar\nmeasures are proposed for predicting the severity of a particular loading\nsequence. A stress-based scalar measure shows superior efficiency in predicting\ninitial liquefaction and pore pressure rise."
    },
    {
        "anchor": "Engineering solid-like structures via an arrested spinodal decomposition: The possibilities to tune the structure of solid like material resulting from\narrested spinodal decomposition is investigated using a system composed of\nlysozyme, a globular protein, dispersed in a water solution as model system for\ncolloids with short range attraction. It is shown that the resulting arrested\nspinodal decomposition is driven by the interplay between the early kinetics of\nthe spinodal decomposition and the dynamical arrest. The initial concentration,\nthe quench depth and speed from the fluid state to the arrested state enable to\ntailor the mesh size of the solid network of the arrested spinodal\ndecomposition.",
        "positive": "From toroidal to rod-like condensates of semiflexible polymers: The competition between toroidal and rod-like conformations as possible\nground states for DNA condensation is studied as a function of the stiffness,\nthe length of the DNA and the form of the long-range interactions between\nneighboring molecules, using analytical theory supported by Monte Carlo\nsimulations. Both conformations considered are characterized by a local nematic\norder with hexagonal packing symmetry of neighboring DNA molecules, but differ\nin global configuration of the chain and the distribution of its curvature as\nit wraps around to form a condensate. The long-range interactions driving the\nDNA condensation are assumed to be of the form pertaining to the attractive\ndepletion potential as well as the attractive counterion induced soft\npotential. In the stiffness-length plane we find a transition between rod-like\nto toroid condensate for increasing stiffness at a fixed chain length $L$.\nStrikingly, the transition line is found to have a $L^{1/3}$ dependence\nirrespective of the details of the long-range interactions between neighboring\nmolecules. When realistic DNA parameters are used, our description reproduces\nrather well some of the experimental features observed in DNA condensates."
    },
    {
        "anchor": "Dynamic density functional theories for inhomogeneous polymer systems\n  compared to Brownian dynamics simulations: Dynamic density functionals (DDFs) are popular tools for studying the\ndynamical evolution of inhomogeneous polymer systems. Here, we present a\nsystematic evaluation of a set of diffusive DDF theories by comparing their\npredictions with data from particle-based Brownian dynamics (BD) simulations\nfor two selected problems: Interface broadening in compressible A/B homopolymer\nblends after a sudden change of the incompatibility parameter, and microphase\nseparation in compressible A:B diblock copolymer melts. Specifically, we\nexamine (i) a local dynamics model, where monomers are taken to move\nindependently from each other, (ii) a nonlocal \"chain dynamics\" model, where\nmonomers move jointly with correlation matrix given by the local chain\ncorrelator, and (iii,iv) two popular approximations to (ii), namely (iii) the\nDebye dynamics model, where the chain correlator is approximated by its value\nin a homogeneous system, and (iv) the computationally efficient \"external\npotential dynamics\" (EPD) model. With the exception of EPD, the value of the\ncompressibility parameter has little influence on the results. In the interface\nbroadening problem, the chain dynamics model reproduces the BD data best.\nHowever, the closely related EPD model produces large spurious artefacts. These\nartefacts disappear when the blend system becomes incompressible. In the\nmicrophase separation problem, the predictions of the nonlocal models (ii-iv)\nagree with each other and significantly overestimate the ordering time, whereas\nthe local model (i) underestimates it. We attribute this to the multiscale\ncharacter of the ordering process, which involves both local and global chain\nrearrangements. To account for this, we propose a mixed local/nonlocal DDF\nscheme which quantitatively reproduces all BD simulation data considered here.",
        "positive": "Generating multi-chain configurations of an inhomogeneous melt from the\n  knowledge of single-chain properties: Mean-field techniques provide a rather accurate description of single-chain\nconformations in spatially inhomogeneous polymer systems containing interfaces\nor surfaces. Intermolecular correlations, however, are not described by the\nmean-field approach and information about the distribution of distance between\ndifferent molecules is lost. Based on the knowledge of the exact equilibrium\nsingle-chain properties in contact with solid substrates, we generate\nmulti-chain configurations that serve as nearly equilibrated starting\nconfigurations for molecular dynamics simulations by utilizing the packing\nalgorithm of Auhl and co-workers [J. Chem. Phys. 119, 12718 (2003)] for\nspatially inhomogeneous systems, i.e., a thin polymer film confined between two\nsolid substrates. The single-chain conformations are packed into the thin film\nconserving the single-chain properties and simultaneously minimizing local\nfluctuations of the density. The extent to which enforcing the\nnear-incompressibility of a dense polymer liquid during the packing process is\nable to re-establish intermolecular correlations is investigated by monitoring\nintermolecular correlation functions and the structure function of density\nfluctuations as a function of the distance from the confining solid substrates."
    },
    {
        "anchor": "Physical picture for fractures in stratified materials: viscoelastic\n  effects in large cracks: We present an intuitive physical picture for fractures in nacre-type\nstratified materials via scaling arguments: strain distributions around a\nfracture are rather different depending on directions and size of fractures. We\nthus observe that viscoelastic effects are important for parallel fractures.\nThese effect are taken into account via the simplest viscoelastic model for\nweakly cross-linked polymer. Within a certain limit, we find a trumpet crack\nshape similar to that in certain polymers and make predictions for the fracture\nenergy of certain stratified materials in this mode.",
        "positive": "Persistence of a pinch in a pipe: The response of low-dimensional solid objects combines geometry and physics\nin unusual ways, exemplified in structures of great utility such as a\nthin-walled tube that is ubiquitous in nature and technology. Here we provide a\nparticularly surprising consequence of this confluence of geometry and physics\nin tubular structures: the anomalously large persistence of a localized pinch\nin an elastic pipe whose effect decays very slowly as an oscillatory\nexponential with a persistence length that diverges as the thickness of the\ntube vanishes, which we confirm experimentally. The result is more a\nconsequence of geometry than material properties, and is thus equally\napplicable to carbon nanotubes as it is to oil pipelines."
    },
    {
        "anchor": "Microscopic basis for pattern formation and anomalous transport in\n  two-dimensional active gels: Active gels are a class of biologically-relevant material containing embedded\nagents that spontaneously generate forces acting on a sparse filament network.\nIn vitro experiments of protein filaments and molecular motors have revealed a\nrange of non- equilibrium pattern formation resulting from motor motion along\nfilament tracks, and there are a number of hydrodynamic models purporting to\ndescribe such systems. Here we present results of extensive simulations\ndesigned to elucidate the microscopic basis underpinning macroscopic flow in\nactive gels. Our numerical scheme includes thermal fluctuations in filament\npositions, excluded volume interactions, and filament elasticity in the form of\nbending and stretching modes. Motors are represented individually as bipolar\nsprings governed by rate-based rules for attachment, detachment and\nunidirectional motion of motor heads along the filament contour. We\nsystematically vary motor density and speed, and uncover parameter regions\ncorresponding to unusual statics and dynamics which overlap but do not\ncoincide. The anomalous statics arise at high motor densities and take the form\nof end-bound localized filament bundles for rapid motors, and extended clusters\nexhibiting enhanced small-wavenumber density fluctuations and power-law\ncluster-size distributions for slow, processive motors. Anomalous dynamics\narise for slow, processive motors over a range of motor densities, and are most\nevident as superdiffusive mass transport, which we argue is the consequence of\na form of effective self-propulsion resulting from the polar coupling between\nmotors and filaments.",
        "positive": "General theory of charge regulation within the Poisson-Boltzmann\n  framework: study of a sticky-charged wall model: This work introduces a sticky-charge wall model as a simple and intuitive\nrepresentation of charge regulation. Implemented within the mean-field level of\ndescription, the model modifies the boundary conditions without affecting the\nunderlying Poisson-Boltzmann (PB) equation of an electrolyte. Employing various\nmodified PB equations, we are able to assess how various structural details of\nan electrolyte influence charge regulation."
    },
    {
        "anchor": "Gaussian density fluctuations and Mode Coupling Theory for supercooled\n  liquids: The equations of motion for the density modes of a fluid, derived from\nNewton's equations, are written as a linear generalized Langevin equation. The\nconstraint imposed by the fluctuation-dissipation theorem is used to derive an\nexact form for the memory function. The resulting equations, solved under the\nassumption that the noise, and consequently density fluctuations, of the liquid\nare gaussian distributed, are equivalent to the random-phase-approximation for\nthe static structure factor and to the well known ideal mode coupling theory\n(MCT) equations for the dynamics. This finding suggests that MCT is the\ncanonical mean-field theory of the fluid dynamics.",
        "positive": "Drop freezing: fine detection of contaminants by measuring the tip angle: In this Letter, we show that the shape of a freezing drop of water can be\nsensitive to the presence of impurities. We measure the tip angle of water\ndrops frozen on a cold plate. The fine changes in tip angle are robustly\ncaptured by our image analysis method, which shows a deviation from that of\npure water in solutions with salt (NaCl), polymer (PEG) and surfactant (TTAB)\nstarting at concentrations of $10^{-6}$, $10^{-4}$ and $10^{-6}$ M\nrespectively. The method could be adapted into a portable water purity tester,\nbut the work also highlights the complexity of water freezing as it is\ninfluenced by trace concentrations of impurities."
    },
    {
        "anchor": "Nanofluidics, from bulk to interfaces: Nanofluidics has emerged recently in the footsteps of microfluidics,\nfollowing the quest of scale reduction inherent to nanotechnologies. By\ndefinition, nanofluidics explores transport phenomena of fluids at the\nnanometer scales. Why is the nanometer scale specific ? What fluid properties\nare probed at nanometric scales ? In other words, why 'nanofluidics' deserves\nits own brand name ? In this critical review, we will explore the vast manifold\nof length scales emerging for the fluid behavior at the nanoscales, as well as\nthe associated mechanisms and corresponding applications. We will in particular\nexplore the interplay between bulk and interface phenomena. The limit of\nvalidity of the continuum approaches will be discussed, as well as the numerous\nsurface induced effects occuring at these scales, from hydrodynamic slippage to\nthe various electro-kinetic phenomena originating from the couplings between\nhydrodynamics and electrostatics. An enlightening analogy between ion transport\nin nanochannels and transport in doped semi-conductors will be discussed.",
        "positive": "Density Functional Theory for Chiral Nematic Liquid Crystals: Even though chiral nematic phases were the first liquid crystals\nexperimentally observed more than a century ago, the origin of the\nthermodynamic stability of cholesteric states is still unclear. In this Letter\nwe address the problem by means of a novel density functional theory for the\nequilibrium pitch of chiral particles. When applied to right-handed hard\nhelices, our theory predicts an entropy-driven cholesteric phase, which can be\neither right- or left-handed, depending not only on the particle shape but also\non the thermodynamic state. We explain the origin of the chiral ordering as an\ninterplay between local nematic alignment and excluded-volume differences\nbetween left- and right-handed particle pairs."
    },
    {
        "anchor": "Impulse distributions in dense granular flows: signatures of large-scale\n  spatial structures: In this paper we report the results of simulations of a 2D gravity driven,\ndissipative granular flow through a hopper system. Measurements of impulse\ndistributions P(I) on the simulated system show flow-velocity-invariant\nbehavior of the distribution for impulses larger than the average impulse <I>.\nFor small impulses, however, P(I) decreases significantly with flow velocity, a\nphenomenon which can be attributed exclusively to collisions between grains\nundergoing frequent collisions. Visualizations of the system also show that\nthese frequently colliding particles tend to form increasingly large linear\nclusters as the flow velocity decreases. A model is proposed for the form of\nP(I), given distributions of cluster size and velocity, which accurately\npredicts the observed form of the distribution. Thus the impulse distribution\nprovides some insight into the formation and properties of these ``dynamic''\nforce chains.",
        "positive": "Macro-orbitals and microscopic theory of a system of interacting bosons: Macro-orbital representation of a particle (detailed account given in\ncond-mat/0603784) has been used to develop the microscopic theory of a system\nof interacting bosons. It concludes that: (i) below certain temperature (say,\n$T_{\\lambda}$), particles assume a state of (q, -q) bound pairs, (ii) the\n$\\lambda-$transition is a consequence of inter-particle quantum correlations\nclubbed with zero-point repulsion and inter-particle attraction and represents\nan onset of the order-disorder of particles in their $\\phi-$space followed\nsimultaneously by their BEC as (q, -q) bound pairs in a state of q = $q_o =\n\\pi/d$ and K = 0, (iii) particles at $T \\le T_{\\lambda}$ acquire collective\nbinding which locks them at <k> = 0, <r> = $\\lambda/2$ and $\\Delta\\phi = 2n\\pi$\n(with n = 1, 2, 3, ...), (iv) the entire system assumes mechanical strain in\ninter-particle bonds and behaves like a single macroscopic molecule, (v) there\nexists an energy gap between the superfluid and normal fluid phases of the\nsystem, (vi) the $\\lambda-$transition represents the twin phenomena of broken\ngauge symmetry and phase coherence, (vii) the system does not have p = 0\ncondensate, (viii) a new kind of quantum quasi-particle \"omon\" (a phononlike\nwave of the oscillations of the momentum coordinates of particles) exists in\nsuperfluid phase, etc. It explains the properties of He-II, including the\norigin of quantized vortices, critical velocities, logarithmic singularity of\nspecific heat, etc. at quantitative level and provides microscopic foundation\nto two fluid theory, $\\Psi-$theory, idea of macroscopic wave function, etc. The\nframework of the theory can unify the physics of interacting bosons and\nfermions."
    },
    {
        "anchor": "Theory and simulation of gelation, arrest and yielding in attracting\n  colloids: We present some recent theory and simulation results addressing the phenomena\nof colloidal gelation at both high and low volume fractions, in the presence of\nshort-range attractive interactions. We discuss the ability of mode-coupling\ntheory and its adaptations to address situations with strong heterogeneity in\ndensity and/or dynamics. We include a discussion of the effect of attractions\non the shear-thinning and yield behaviour under flow.",
        "positive": "The \"magic\" angle in the self-assembly of colloids suspended in a\n  nematic host phase: Using extensive Monte Carlo (MC) simulations of colloids immersed in a\nnematic liquid crystal we compute an effective interaction potential via the\nlocal nematic director field and its associated order parameter. The effective\npotential consists of a local Landau-de Gennes (LdG) and a Frank elastic\ncontribution. Molecular expressions for the LdG expansion coefficients are\nobtained via classical density functional theory (DFT). The DFT result for the\nLdG parameter $A$ is improved by locating the phase transition through\nfinite-size scaling theory. We consider effective interactions between a pair\nof homogeneous colloids with Boojum defect topology. In particular, colloids\nattract each other if the angle between their center-of-mass distance vector\nand the far-field nematic director is about $30^{\\circ}$ which settles a\nlong-standing discrepancy between theory and experiment. Using the effective\npotential in two-dimensional MC simulations we show that self-assembled\nstructures formed by the colloids are in excellent agreement with experimental\ndata."
    },
    {
        "anchor": "Rheology and Contact Lifetime Distribution in Dense Granular Flows: We study the rheology and distribution of interparticle contact lifetimes for\ngravity-driven, dense granular flows of non-cohesive particles down an inclined\nplane using large-scale, three dimensional, granular dynamics simulations.\nRather than observing a large number of long-lived contacts as might be\nexpected for dense flows, brief binary collisions predominate. In the hard\nparticle limit, the rheology conforms to Bagnold scaling, where the shear\nstress is quadratic in the strain rate. As the particles are made softer,\nhowever, we find significant deviations from Bagnold rheology; the material\nflows more like a viscous fluid. We attribute this change in the collective\nrheology of the material to subtle changes in the contact lifetime distribution\ninvolving the increasing lifetime and number of the long-lived contacts in the\nsofter particle systems.",
        "positive": "Boundary-induced inhomogeneity of particle layers in the solidification\n  of suspensions: When a suspension freezes, a compacted particle layer builds up at the\nsolidification front with noticeable implications on the freezing process. In a\ndirectional solidification experiment of monodispersed suspensions in thin\nsamples, we evidence a link between the thickness of this layer and the sample\ndepth. We attribute it to an inhomogeneity of particle density induced by the\nsample plates. A mechanical model enables us to relate it to the layer\nthickness with a dependency on the sample depth and to select the distribution\nof particle density that yields the best fit to our data. This distribution\ninvolves an influence length of sample plates of about nine particle diameters.\nThese results clarify the implications of boundaries on suspension freezing.\nThey may be useful to model polydispersed suspensions since large particles\ncould play the role of smooth boundaries with respect to small ones."
    },
    {
        "anchor": "Self-assembly of three-dimensional ensembles of magnetic particles with\n  laterally shifted dipoles: We consider a model of colloidal spherical particles carrying a permanent\ndipole moment which is laterally shifted out of the particles' geometrical\ncentres, i.e. the dipole vector is oriented perpendicular to the radius vector\nof the particles. Varying the shift $\\delta$ from the centre, we analyze ground\nstate structures for two, three and four hard spheres, using a simulated\nannealing procedure. We also compare to earlier ground state results. We then\nconsider a bulk system at finite temperatures and different densities. Using\nMolecular Dynamics simulations, we examine the equilibrium self-assembly\nproperties for several shifts. Our results show that the shift of the dipole\nmoment has a crucial impact on both, the ground state configurations as well as\nthe self-assembled structures at finite temperatures.",
        "positive": "Displacement fields of point defects in two-dimensional colloidal\n  crystals: Point defects such as interstitials, vacancies, and impurities in otherwise\nperfect crystals induce complex displacement fields that are of long-range\nnature. In the present paper we study numerically the response of a\ntwo-dimensional colloidal crystal on a triangular lattice to the introduction\nof an interstitial particle. While far from the defect position the resulting\ndisplacement field is accurately described by linear elasticity theory, lattice\neffects dominate in the vicinity of the defect. In comparing the results of\nparticle based simulations with continuum theory, it is crucial to employ\ncorresponding boundary conditions in both cases. For the periodic boundary\ncondition used here, the equations of elasticity theory can be solved in a\nconsistent way with the technique of Ewald summation familiar from the\nelectrostatics of periodically replicated systems of charges and dipoles. Very\ngood agreement of the displacement fields calculated in this way with those\ndetermined in particle simulations is observed for distances of more than about\n10 lattice constants. Closer to the interstitial, strongly anisotropic\ndisplacement fields with exponential behavior can occur for certain defect\nconfigurations. Here we rationalize this behavior with a simple bead-spring\nthat relates the exponential decay constant to the elastic constants of the\ncrystal."
    },
    {
        "anchor": "Optical Analog of the Iordanskii Force in a Bose-Einstein Condensate: A vortex in a Bose-Einstein condensate generates the optical analog of the\nAharonov-Bohm effect when illuminated with slow light. In contrast to the\noriginal Aharonov-Bohm effect the vortex will exchange forces with the light\nthat lead to a measurable motion of the vortex.",
        "positive": "On the singular nature of the elastocapillary ridge: The functionality of soft interfaces is crucial to many applications in\nbiology and surface science. Recent studies have used liquid drops to probe the\nsurface mechanics of elastomeric networks. Experiments suggest an intricate\nsurface elasticity, also known as the Shuttleworth effect, where surface\ntension is not constant but depends on substrate deformation. However,\ninterpretations have remained controversial due to singular elastic\ndeformations, induced exactly at the point where the droplet pulls the network.\nHere we reveal the nature of the elastocapillary singularity on a hyperelastic\nsubstrate with various constitutive relations for the interfacial energy.\nFirst, we finely resolve the vicinity of the singularity using goal-adaptive\nfinite element simulations. This confirms the universal validity, also at large\nelastic deformations, of the previously disputed Neumann's law for the contact\nangles. Subsequently, we derive exact solutions of nonlinear elasticity that\ndescribe the singularity analytically. These solutions are in perfect agreement\nwith numerics, and show that the stretch at the contact line, as previously\nmeasured experimentally, consistently points to a strong Shuttleworth effect.\nFinally, using Noether's theorem we provide a quantitative link between wetting\nhysteresis and Eshelby-like forces, and thereby offer a complete framework for\nsoft wetting in the presence of the Shuttleworth effect."
    },
    {
        "anchor": "Activity-suppressed phase separation: We use a continuum model to examine the effect of activity on a phase\nseparating mixture of an extensile active nematic and a passive fluid. We\nhighlight the distinct role of previously considered interfacial active\nstresses and bulk active stresses that couple to liquid crystalline degrees of\nfreedom. Interfacial active stresses can arrest phase separation, as previously\ndemonstrated. Bulk extensile active stresses can additionally strongly suppress\nphase separation by sustained self-stirring of the fluid, substantially\nreducing the size of the coexistence region in the temperature/concentration\nplane relative to that of the passive system. The phase separated state is a\ndynamical emulsion-like steady state of continuously splitting and merging\ndroplets, as suggested by recent experiments. Using scaling analysis and\nsimulations, we identify various regimes for the dependence of droplet size on\nactivity. These results can provide a criterion for identifying the mechanisms\nresponsible for arresting phase separation in experiments.",
        "positive": "Wave mixing of optical pulses and Bose-Einstein condensates: We investigate theoretically the four-wave mixing of optical and matter waves\nresulting from the scattering of a short light pulse off an atomic\nBose-Einstein condensate, as recently demonstrated by D. Schneble {\\em et al.}\n[ Science {\\bf 300}, 475 (2003)]. We show that atomic ``pair production'' from\nthe condensate results in the generation of both forward- and\nbackward-propagating matter waves. These waves are characterized by different\nphase-matching conditions, resulting in different angular distributions and\ntemporal evolutions."
    },
    {
        "anchor": "Theoretical models for single-molecule DNA and RNA experiments: from\n  elasticity to unzipping: We review statistical-mechanical theories of single-molecule\nmicromanipulation experiments on nucleic acids. First, models for describing\npolymer elasticity are introduced. We then review how these models are used to\ninterpret single-molecule force-extension experiments on single-stranded and\ndouble-stranded DNA. Depending on the force and the molecules used, both smooth\nelastic behaviors and abrupt structural transitions are observed. Third, we\nshow how combining the elasticity of two single nucleic acid strands with a\ndescription of the base-pairing interactions between them explains much of the\nphenomenology and kinetics of RNA and DNA `unzipping' experiments.",
        "positive": "Rotational behavior of red blood cells in suspension---a mesoscale\n  simulation study: The nature of blood as a suspension of red blood cells makes computational\nhemodynamics a demanding task. Our coarse-grained blood model, which builds on\na lattice Boltzmann method for soft particle suspensions, enables the study of\nthe collective behavior of the order of 10^6 cells in suspension. After\ndemonstrating the viscosity measurement in Kolmogorov flow, we focus on the\nstatistical analysis of the cell orientation and rotation in Couette flow. We\nquantify the average inclination with respect to the flow and the nematic order\nas a function of shear rate and hematocrit. We further record the distribution\nof rotation periods around the vorticity direction and find a pronounced peak\nin the vicinity of the theoretical value for free model cells even though\ncell-cell interactions manifest themselves in a substantial width of the\ndistribution."
    },
    {
        "anchor": "Micro-mechanics of fabric and failure in granular materials: The paper addresses the underlying source of two forms of induced anisotropy\nin granular materials: contact orientation anisotropy and contact force\nanisotropy. A rational, mathematical structure is reviewed for the manner in\nwhich fabric anisotropy emerges and evolves during loading. Fabric is expressed\nas an orientation density, and transport phenomena such as convection, contact\ngeneration, and diffusion control the rate of fabric evolution during loading.\nThe paper proposes specific measurable forms for all terms, based upon the\nmicro-mechanics of particle interactions. Discrete element (DEM) simulations\nare used to verify and quantify these terms, so that the theory can be applied\nto general loading conditions. The DEM simulations are of densely packed\ndurable spheres, and the emphasis is on soil behavior at large strains,\nspecifically on fabric and strength at the critical state. Once the theory has\nbeen developed and quantified, it is applied to predict the effect of the\nintermediate principal stress on strength.",
        "positive": "On the relaxation dynamics of glass-forming systems: Insights from\n  computer simulations: We discuss the relaxation dynamics of a simple lattice gas model for\nglass-forming systems and show that with increasing density of particles this\ndynamics slows down very quickly. By monitoring the trajectory of tagged\nparticles we find that their motion is very heterogeneous in space and time,\nleading to regions in space in which there is a fast dynamics and others in\nwhich it is slow. We determine how the geometric properties of these quickly\nrelaxing regions depend on density and time. Motivated by this heterogeneous\nhopping dynamics, we use a simple model, a variant of a continuous time random\nwalk, to characterize the relaxation dynamics. In particular we find from this\nmodel that for large displacements the self part of the van Hove function shows\nan exponential tail, in agreement with recent findings from experiments and\nsimulations of glass-forming systems."
    },
    {
        "anchor": "Alignment of cylindrical colloids near chemically patterned substrates\n  induced by critical Casimir torques: Recent experiments have demonstrated a fluctuation-induced lateral trapping\nof spherical colloidal particles immersed in a binary liquid mixture near its\ncritical demixing point and exposed to chemically patterned substrates.\nInspired by these experiments, we study this kind of effective interaction,\nknown as the critical Casimir effect, for elongated colloids of cylindrical\nshape. This adds orientational degrees of freedom. When the colloidal particles\nare close to a chemically structured substrate, a critical Casimir torque\nacting on the colloids emerges. We calculate this torque on the basis of the\nDerjaguin approximation. The range of validity of the latter is assessed via\nmean-field theory. This assessment shows that the Derjaguin approximation is\nreliable in experimentally relevant regimes, so that we extend it to Janus\nparticles endowed with opposing adsorption preferences. Our analysis indicates\nthat critical Casimir interactions are capable of achieving well-defined,\nreversible alignments both of chemically homogeneous and of Janus cylinders.",
        "positive": "Generation of vector beams with liquid crystal disclination lines: We report that guiding light beams, ranging from continuous beams to\nfemtosecond pulses, along liquid crystal defect lines can transform them into\nvector beams with various polarization profiles. Using Finite Difference Time\nDomain numerical solving of Maxwell equations, we confirm that the defect in\nthe orientational order of the liquid crystal induces a defect in the light\nfield with twice the winding number of the liquid crystal defect, coupling the\ntopological invariants of both fields. For example, it is possible to transform\nuniformly-polarized light into light with a radial polarization profile. Our\napproach also correctly yields a zero-intensity region near the defect core,\nwhich is always present in areas of discontinuous light polarization or phase.\nUsing circularly polarized incident light, we show that defects with\nnon-integer winding numbers can be obtained, where topological constants are\npreserved by phase vortices, demonstrating coupling between the light's spin,\norbital angular momentum and polarization profile. Further, we find an\nultrafast femtosecond laser pulse travelling along a defect line splits into\nmultiple intensity regions, again depending on the defect's winding number,\nallowing applications in beam steering and filtering. Finally, our approach\ndescribing generation of complex optical fields via coupling with topological\ndefect lines in optically birefringent nematic fluids can be easily extended to\nhigh-intensity beams that affect nematic ordering."
    },
    {
        "anchor": "Modelling phase separation in amorphous solid dispersions: Much work has been devoted to analysing thermodynamic models for solid\ndispersions with a view to identifying regions in the phase diagram where\namorphous phase separation or drug recrystallization can occur. However,\ndetailed partial differential equation non-equilibrium models that track the\nevolution of solid dispersions in time and space are lacking. Hence theoretical\npredictions for the timescale over which phase separation occurs in a solid\ndispersion are not available. In this paper, we address some of these\ndeficiencies by (i) constructing a general multicomponent diffusion model for a\ndissolving solid dispersion; (ii) specializing the model to a binary\ndrug/polymer system in storage; (iii) deriving an effective concentration\ndependent drug diffusion coefficient for the binary system, thereby obtaining a\ntheoretical prediction for the timescale over which phase separation occurs;\nand (iv) presenting a detailed numerical investigation of the HPMCAS/Felodipine\nsystem assuming a Flory-Huggins activity coefficient. The numerical simulations\nexhibit numerous interesting phenomena, such as the formation of polymer\ndroplets and strings, Ostwald ripening/coarsening, phase inversion, and\ndroplet-to-string transitions.",
        "positive": "The Geometry of Crumpled Paper: We measure the geometry of a crumpled sheet of paper with laser-aided\ntopography and discuss its statistical properties. The curvature of an\nelasto-plastic fold scales linearly with applied force. The curvature\ndistribution follows an exponential form with regions of high curvature\nlocalized along ridges. The measured ridge length distribution is consistent\nwith a hierarchical model for ridge breaking during crumpling. A large fraction\nof the ridges are observed to terminate without bifurcating and the ridge\nnetwork connectedness is not as complete as anticipated. The self-affinity of\nthe surface is characterized by a Hurst exponent of $0.72\\pm 0.01$ in contrast\nwith previous results."
    },
    {
        "anchor": "Capillary Network Model: Capillary Power and Effective Permeability: A simple model of two-phase flow in porous media is presented. A connection\nis made to statistical mechanics by applying capillary power as a constraint.\nStochastic sampling is then used to test the validity of this approach. Good\nagreement is found between stochastic sampling and time stepping for flow-rates\nabove a transition value.",
        "positive": "Voltage-controlled topological interface states for bending waves in\n  soft dielectric phononic crystal plates: The operating frequency range of passive topological phononic crystals is\ngenerally fixed and narrow, limiting their practical applications. To overcome\nthis difficulty, here we design and investigate a one-dimensional soft\ndielectric phononic crystal (PC) plate system with actively tunable topological\ninterface states via the mechanical and electric loads. We use nonlinear\nelectroelasticity theory and linearized incremental theory to derive the\ngoverning equations. First we determine the nonlinear static response of the\nsoft dielectric PC plate subjected to a combination of axial force and electric\nvoltage. Then we study the motion of superimposed incremental bending waves. By\nadopting the Spectral Element Method, we obtain the dispersion relation for the\ninfinite PC plate and the transmission coefficient for the finite PC plate\nwaveguide. Numerical results show that the low-frequency topological interface\nstate exists at the interface of the finite phononic plate waveguide with two\ntopologically different elements. By simply adjusting the axial force or the\nelectric voltage, an increase or decrease in the frequency of the topological\ninterface state can be realized. Furthermore, applying the electric voltage\nseparately on different elements of the PC plate waveguide is a flexible and\nsmart method to tune the topological interface state in a wide range. These\nresults provide guidance for designing soft smart wave devices with\nlow-frequency tunable topological interface states."
    },
    {
        "anchor": "Spontaneous propulsion of an isotropic colloid in a phase-separating\n  environment: The motion of active colloids is generally achieved through their anisotropy,\nas exemplified by Janus colloids. Recently, there was a growing interest in the\npropulsion of isotropic colloids, which requires some local symmetry breaking.\nAlthough several mechanisms for such propulsion were proposed, little is known\nabout the role played by the interactions within the environment of the\ncolloid, which can have a dramatic effect on its propulsion. Here, we propose a\nminimal model of an isotropic colloid in a bath of solute particles that\ninteract with each other. These interactions lead to a spontaneous phase\ntransition close to the colloid, to directed motion of the colloid over very\nlong timescales and to significantly enhanced diffusion, in spite of the\ncrowding induced by solute particles. We determine the range of parameters\nwhere this effect is observable in the model, and we propose an effective\nLangevin equation that accounts for it and allows one to determine the\ndifferent contributions at stake in self-propulsion and enhanced diffusion.",
        "positive": "Forced dewetting on porous media: We study the dewetting of a porous plate withdrawn from a bath of fluid. The\nmicroscopic contact angle is fixed to zero and the flow is assumed to be\nparallel to the plate (lubrication approximation). The ordinary differential\nequation involving the position of the water surface is analysed in phase space\nby means of numerical integration. We show the existence of a critical value of\nthe capillary number $\\eta U / \\gamma$, above which no stationary contact line\ncan exist. An analytical model, based on asymptotic matching is developed, that\nreproduces the dependence of the critical capillary number on the angle of the\nplate with respect to the horizontal for large control parameters (3/2 power\nlaw)."
    },
    {
        "anchor": "Enhancement of the nonlinear optical absorption of the E7 liquid crystal\n  at the nematic-isotropic transition: We present an experimental study of the nonlinear optical absorption of the\neutectic mixture E7 at the nematic-isotropic phase transition by the Z-scan\ntechnique, under a continuos wave excitation at 532 nm. In the nematic region,\nthe effective nonlinear optical coefficient \\beta for an extraordinary beam is\nnegative and for an ordinary beam is positive, being null in the isotropic\nphase. The parameter S_{NL} defined in terms of the nonlinear absorption\ncoefficients in a similar way than the optical order parameter from the linear\ndichoic ratio behavies like an order parameter with a critical exponent\n0.22+-0.05, in good agreement with the tri-critical hipothesis of the N-I\ntransition.",
        "positive": "Inverse Primitive Path Analysis: The primitive-path analysis (PPA) {[}R. Everaers et al. Science 303, 823,\n(2004){]} is an algorithm that transforms a model polymer melt into its\ntopologically equivalent mesh by removing excess contour length stored in\nthermal fluctuations. Here we present an inverse PPA algorithm that gradually\nreintroduces contour length in a PPA mesh to produce an topologically\nequilvalent polymer melt. This enables the generation of model polymer\nmaterials with well controlled topology. As an illustration, we generate\nknitted model polymer materials with a 2D cubic lattice of entanglement points\nusing a synthetic PPA mesh as a starting point. We also show how to combine PPA\nand inverse PPA to accelerate stress relaxation approximately by an order of\nmagnitude in simulation time. This reduces the computational cost of\ncomputational studies of structure-property relations for polymer materials."
    },
    {
        "anchor": "Allosteric interactions in a birod model of DNA: Allosteric interactions between molecules bound to DNA at distant locations\nhave been known for a long time. The phenomenon has been studied via\nexperiments and numerical simulations, but a comprehensive understanding\ngrounded in a theory of DNA elasticity remains a challenge. Here we quantify\nallosteric interactions between two entities bound to DNA by using the theory\nof birods. We recognize that molecules bound to DNA cause local deformations\nthat can be captured in a birod model which consists of two elastic strands\ninteracting via an elastic web representing the base-pairs. We show that the\ndisplacement field caused by bound entities decays exponentially with distance\nfrom the binding site. We compute the interaction energy between two proteins\non DNA as a function of distance between them and find that it decays\nexponentially while oscillating with the periodicity of the double-helix, in\nexcellent agreement with experiments. The decay length of the interaction\nenergy can be determined in terms of the mechanical properties of the strands\nand the webbing in our birod model, and it varies with the GC content of the\nDNA. Our model provides a framework for viewing allosteric interactions in DNA\nwithin the ambit of configurational forces of continuum elasticity.",
        "positive": "Electrophoretic mobility without charge driven by spontaneous\n  polarization of the nanoparticle/water interface: Polarization of the interface, spontaneously occurring when water is in\ncontact with hydrophobic solutes or air, couples with the uniform external\nfield to produce a non-zero force acting on a suspended particle. This force\nexists even in the absence of a net particle charge, and its direction is\naffected by the first-order, dipolar and the second-order, qudrupolar\norientational order parameters of the interfacial water. The quadrupolar\npolarization gives rise to an effectively negative charge. The corresponding\nsurface charge density is inversely proportional to the area of the shear\nsurface. As a result, the overall contribution from the quadrupolar\npolarization to the particle mobility becomes negligible compared to\nexperimentally reported values for particles exceeding a few nanometers in\nsize. The dipolar order of the interface dominates the zero-charge mobility of\nsub-micron particles. The corresponding electrokinetic charge is determined by\nthe preferential orientation of interfacial dipoles relative to the surface\nnormal."
    },
    {
        "anchor": "Length-scales of Dynamic Heterogeneity in a Driven Binary Colloid: Here we study characteristic length scales in an aqueous suspension of\nsymmetric oppositely charged colloid subject to a uniform electric field by\nBrownian Dynamics simulations. We consider a sufficiently strong electric field\nwhere the like charges in the system form macroscopic lanes. We construct\nspatial correlation functions characterizing structural order and that of\nparticles of different mobilities in-plane transverse to the electric field at\na given time. We call these functions as equal time density correlation\nfunction (ETDCF). The ETDCF between particles of different charges,\nirrespective of mobilities, are called structural ETDCFs, while those between\nparticles of different mobilities are called the dynamic ETDCF. We extract the\ncharacteristic length of correlation by fitting the envelopes of the ETDCFs to\nexponential dependence. We find that structural ETDCF and the dynamical-ETDCFs\nof the slow particles increase with time. This suggests that the slow particles\nundergo microphase separation in the background of the fast particles which\ndrive the structural pattern in the plane transverse to the lanes. The ETDCFs\ncan be measured for colloidal systems directly following particle motion by\nvideo-microscopy and may be useful to understand patterns out of equilibrium.",
        "positive": "A simple model for heterogeneous flows of yield stress fluids: Various experiments evidence spatial heterogeneities in sheared yield stress\nfluids. To account for heterogeneities in the velocity gradient direction, we\nuse a simple model corresponding to a non-monotonous local constitutive curve\nand study a simple shear geometry. Different types of boundary conditions are\nconsidered. Under controlled macroscopic shear stress $\\Sigma$, we find\nhomogeneous flow in the bulk and a hysteretic macroscopic stress - shear rate\ncurve. Under controlled macroscopic shear rate $\\dot{\\Gamma}$, shear banding is\npredicted within a range of values of $\\dot{\\Gamma}$. For small shear rates,\nstick slip can also be observed. These qualitative behaviours are robust when\nchanging the boundary conditions."
    },
    {
        "anchor": "Interpretation of saddle-splay and the Oseen-Frank free energy in liquid\n  crystals: This article re-examines a classic question in liquid-crystal physics: What\nare the elastic modes of a nematic liquid crystal? The analysis uses a recent\nmathematical construction, which breaks the director gradient tensor into four\ndistinct types of mathematical objects, representing splay, twist, bend, and a\nfourth deformation mode. With this construction, the Oseen-Frank free energy\ncan be written as the sum of squares of the four modes, and saddle-splay can be\nregarded as bulk rather than surface elasticity. This interpretation leads to\nan alternative way to think about several previous results in liquid-crystal\nphysics, including: (1) free energy balance between cholesteric and blue\nphases, (2) director deformations in hybrid-aligned-nematic cells, (3)\nspontaneous twist of achiral liquid crystals confined in a torus or cylinder,\nand (4) curvature of smectic layers.",
        "positive": "Liquid Metal Transformers: The room temperature liquid metal is quickly emerging as an important\nfunctional material in a variety of areas like chip cooling, 3D printing or\nprinted electronics etc. With diverse capabilities in electrical, thermal and\nflowing behaviors, such fluid owns many intriguing properties that had never\nbeen anticipated before. Here, we show a group of unconventional phenomena\noccurring on the liquid metal objects. Through applying electrical field on the\nliquid metals immersed in water, a series of complex transformation behaviors\nsuch as self-assembling of a sheet of liquid metal film into a single sphere,\nquick mergences of separate metal droplets, controlled self-rotation and planar\nlocomotion of liquid metal objects can be realized. Meanwhile, it was also\nfound that two accompanying water vortexes were induced and reliably swirled\nnear the rotating liquid metal sphere. Further, effects of the shape, size,\nvoltage, orientation and geometries of the electrodes to control the liquid\nmetal transformers were clarified. Such events are hard to achieve otherwise on\nrigid metal or conventional liquid spheres. This finding has both fundamental\nand practical significances which suggest a generalized way of making smart\nsoft machine, collecting discrete metal fluids, as well as flexibly\nmanipulating liquid metal objects including accompanying devices."
    },
    {
        "anchor": "Production of Porous Glass-foam Materials from Photovoltaic Panel Waste\n  Glass: The Solar energy production is growing quickly for the global demand of\nrenewa-ble one, decrease the dependence on fossil fuels. However, disposing of\nused pho-tovoltaic (PV) panels will be a serious environmental challenge in the\nfuture dec-ades since the solar panels would eventually become a source of\nhazardous waste. The potential of waste solar panel glass to generate porous\nglass material with the addition of CaCO3 and water glass was assessed in this\nstudy. The porous glass firing temperature range, from 830{\\deg}C - 910{\\deg}C,\nwas determined using a simu-lation of heating microscope technique. The created\nsamples have the smallest volumetric density of 0.25 g/cm3 and the largest\nwater absorption of 303.08 wt.%. This indicates that the image analysis of\nsamples during the heating process could be used to identify the firing\ntemperature for better foaming, which was favorably indicated by specific\nphysicochemical parameters. The created glass-foam mate-rials with an apparent\nporosity up to 81.49% could be used as a water-retaining medium in hydroponic\nand aquaponic systems",
        "positive": "Elasticity in Amorphous Solids: Nonlinear or Piece-Wise Linear?: Quasi-static strain-controlled measurements of stress vs strain curves in\nmacroscopic amorphous solids result in a nonlinear looking curve that ends up\neither in mechanical collapse or in a steady-state with fluctuations around a\nmean stress that remains constant with increasing strain. It is therefore very\ntempting to fit a nonlinear expansion of the stress in powers of the strain. We\nargue here that at low temperatures the meaning of such an expansion needs to\nbe reconsidered. We point out the enormous difference between quenched and\nannealed averages of the stress vs. strain curves, and propose that a useful\ndescription of the mechanical response is given by a stress (or strain)\ndependent shear modulus for which a theoretical evaluation exists. The elastic\nresponse is piece-wise linear rather than nonlinear."
    },
    {
        "anchor": "Growth-induced phase changes in swimming bacteria at finite liquid\n  interfaces: We introduce a system of bacteria confined to a finite 2D oil-water interface\nand driven on two distinct time scales by motility and by growth. The combined\neffect of activity on different time scales creates transitions between several\ncommon collective behaviors. These transitions are observed using time-lapse\nmicroscopy with high spatial and temporal resolution over eight hours. We\nsequentially observe an initial dilute state, a clustered state, an active\nturbulent state, and a glassy state, and we are able to directly observe and\ncharacterize the transitions between these states. This system allows the\ninvestigation of emergent effects surrounding transitions between phases,\nexpanding on studies that have considered them in isolation. In particular, a\npeak in the velocity correlation length is observed at the turbulent-glassy\ntransition, suggesting that this transition significantly increases the active\nturbulent length scale.",
        "positive": "Mechanical annealing and memories in a disordered solid: Shearing a disordered or amorphous solid for many cycles with a constant\nstrain amplitude can anneal it, relaxing a sample to a steady state that\nencodes a memory of that amplitude. This steady state also features a\nremarkable stability to amplitude variations that allows one to read the\nmemory. Here we shed new light on both annealing and memory, by considering how\nto mechanically anneal a sample to have as little memory content as possible.\nIn experiments, we show that a \"ring-down\" protocol reaches a comparable steady\nstate, but with no discernible memories and minimal structural anisotropy. We\nintroduce a method to characterize the population of rearrangements within a\nsample, and show how it connects with the response to amplitude variation and\nthe size of annealing steps. These techniques can be generalized to other forms\nof glassy matter and a wide array of disordered solids, especially those that\nyield by flowing homogeneously."
    },
    {
        "anchor": "Aging after shear rejuvenation in a soft glassy colloidal suspension:\n  evidence for two different regimes: The aging dynamics after shear rejuvenation in a glassy, charged clay\nsuspension have been investigated through dynamic light scattering (DLS). Two\ndifferent aging regimes are observed: one is attained if the sample is\nrejuvenated before its gelation and one after the rejuvenation of the gelled\nsample. In the first regime, the application of shear fully rejuvenates the\nsample, as the system dynamics soon after shear cessation follow the same aging\nevolution characteristic of normal aging. In the second regime, aging proceeds\nvery fast after shear rejuvenation, and classical DLS cannot be used. An\noriginal protocol to measure an ensemble averaged intensity correlation\nfunction is proposed and its consistency with classical DLS is verified. The\nfast aging dynamics of rejuvenated gelled samples exhibit a power law\ndependence of the slow relaxation time on the waiting time.",
        "positive": "Depinning by Fracture in a Glassy Background: We force a single particle through a two-dimensional simulated glass. We find\nthat the particle velocity obeys a robust power law that persists to drives\nwell above threshold. As the single driven particle moves, it induces\ncooperative distortions in the surrounding medium. We show theoretically that a\nfracture model for these distortions produces power law behavior, and discuss\nimplications for experimental probes of soft matter systems."
    },
    {
        "anchor": "Motility-Induced Phase Separation: Self-propelled particles include both self-phoretic synthetic colloids and\nvarious micro-organisms. By continually consuming energy, they bypass the laws\nof equilibrium thermodynamics. These laws enforce the Boltzmann distribution in\nthermal equilibrium: the steady state is then independent of kinetic\nparameters. In contrast, self-propelled particles tend to accumulate where they\nmove more slowly. They may also slow down at high density, for either\nbiochemical or steric reasons. This creates positive feedback which can lead to\nmotility-induced phase separation (MIPS) between dense and dilute fluid phases.\nAt leading order in gradients, a mapping relates variable-speed, self-propelled\nparticles to passive particles with attractions. This deep link to equilibrium\nphase separation is confirmed by simulations, but generally breaks down at\nhigher order in gradients: new effects, with no equilibrium counterpart, then\nemerge. We give a selective overview of the fast-developing field of MIPS,\nfocusing on theory and simulation but including a brief speculative survey of\nits experimental implications.",
        "positive": "Morphology and Kinetics of Random Sequential Adsorption of Superballs:\n  From Hexapods to Cubes: Superballs represent a class of particles whose shapes are defined by\n${|x|}^{2p}+{|y|}^{2p}+{|z|}^{2p} \\le R^{2p}$, with $p\\in(0,\\infty)$ being the\n\"deformation parameter\". $0<p<0.5$ represents a family of hexapodlike (concave\noctahedrallike) particles, while for $0.5\\leq p<1$ and $p>1$ one has,\nrespectively, families of convex octahedrallike and cubelike particles, with\n$p=1,\\;0.5$ and $\\infty$ representing spheres, octahedra, and cubes. Colloidal\nzeolite suspensions, catalysis, and adsorption, as well as biomedical magnetic\nnanoparticles are but a few of the applications of packing of superballs. We\nintroduce a universal method for simulating random sequential adsorption of\nsuperballs, which we refer to as \"low-entropy\" algorithm, in contrast with the\nconventional algorithm that represents a \"high-entropy\" method. The two\nalgorithms yield, respectively, precise estimates of the jamming fraction\n$\\phi_\\infty(p)$ and $\\nu(p)$, the exponent that characterizes the kinetics of\nadsorption at long times $t$, $\\phi(\\infty)-\\phi(t)\\sim t^{-\\nu(p)}$. Precise\nestimates of $\\phi_\\infty(p)$ and $\\nu(p)$ are obtained and shown to be in\nagreement, in some special limits, with the existing analytical and numerical\nresults."
    },
    {
        "anchor": "Cavitation in elastomers: A review of the evidence against elasticity: In spite of the growing body of evidence against it, the elasticity view of\nthe phenomenon of cavitation in elastomers continues to be utilized in numerous\nstudies. In this context, the main objective of this paper is to provide a\ncomprehensive review of the existing evidence that settles that cavitation in\nelastomers is \\emph{not} a purely elastic phenomenon. To that end, a review is\nfirst given of the experimental observations of cavitation in elastomers --\ngathered since the 1930s until present times -- as well as of its theoretical\ndescription as an elastic phenomenon -- whose development started in the 1950s\nand was substantially completed by the 2010s. The latter is then confronted to\nthe former to pinpoint the reasons why the elastic behavior of elastomers\ncannot possibly explain the experimental observations. The last part of the\npaper includes a brief summary of the current view of cavitation as a fracture\nphenomenon and an outlook for the field in that direction.",
        "positive": "Neutron reflection from the surface of normal and superfluid 4He: The reflection of neutrons from a helium surface has been observed for the\nfirst time. The 4He surface is smoother in the superfluid state at 1.54 K than\nin the case of the normal liquid at 2.3 K. In the superfluid state we also\nobserve a surface layer ~200 Angstroms thick which has a subtly different\nneutron scattering cross-section, which may be explained by an enhanced\nBose-Einstein condensate fraction close to the helium surface."
    },
    {
        "anchor": "Behavior of rod-like polyelectrolytes near an oppositely charged surface: The behavior of highly charged short rod-like polyelectrolytes near\noppositely charged planar surfaces is investigated by means of Monte Carlo\nsimulations. A detailed microstructural study, including monomer and fluid\ncharge distribution, and chain orientation, is provided. The influence of chain\nlength, substrate's surface-charge-density and image forces is considered. Due\nto the lower chain-entropy (compared to flexible chains), our simulation data\nshow that rod-like polyelectrolytes can, in general, better adsorb than\nflexible ones do. Nonetheless, at low substrate-dielectric-constant, it is\nfound that repulsive image forces tend to significantly reduce this\ndiscrepancy.",
        "positive": "Frustrated colloidal ordering and fully packed loops in arrays of\n  optical traps: We propose that a system of colloidal particles interacting with a honeycomb\narray of optical traps that each contain three wells can be used to realize a\nfully packed loop model. One of the phases in this system can be mapped to\nBaxter's three-coloring problem, offering an easily accessible physical\nrealization of this problem. As a function of temperature and interaction\nstrength, we find a series of phases, including long range ordered loop or\nstripe states, stripes with sliding symmetries, random packed loop states, and\ndisordered states in which the loops break apart. Our geometry could be\nconstructed using ion trap arrays, BEC vortices in optical traps, or magnetic\nvortices in nanostructured superconductors."
    },
    {
        "anchor": "Sterols sense swelling in lipid bilayers: In the mimetic membrane system of phosphatidylcholine bilayers, thickening\n(pre-critical behavior, anomalous swelling) of the bilayers is observed, in the\nvicinity of the main transition, which is non-linear with temperature. The\nsterols cholesterol and androsten are used as sensors in a time-resolved\nsimultaneous small- and wide angle x-ray diffraction study to investigate the\ncause of the thickening. We observe precritical behavior in the pure lipid\nsystem, as well as with sterol concentrations less than 15%. To describe the\nprecritical behavior we introduce a theory of precritical phenomena.The good\ntemperature resolution of the data shows that a theory of the influence of\nfluctuations needs modification. The main cause of the critical behavior\nappears to be a changing hydration of the bilayer.",
        "positive": "A Topologically Driven Glass in Ring Polymers: The static and dynamic properties of ring polymers in concentrated solutions\nremains one of the last deep unsolved questions in Polymer Physics. At the same\ntime, the nature of the glass transition in polymeric systems is also not well\nunderstood. In this work we study a novel glass transition in systems made of\ncircular polymers by exploiting the topological constraints that are\nconjectured to populate concentrated solutions of rings. We show that such\nrings strongly inter-penetrate through one another, generating an extensive\nnetwork of topological interactions that dramatically affects their dynamics.\nWe show that a kinetically arrested state can be induced by randomly pinning a\nsmall fraction of the rings. This occurs well above the classical glass\ntransition temperature at which microscopic mobility is lost. Our work\ndemonstrates both the existence of long-lived inter-ring penetrations and also\nrealises a novel, topologically-induced, glass transition."
    },
    {
        "anchor": "The Excess Proton at the Air-Water Interface: The Role of Instantaneous\n  Liquid Interfaces: The magnitude of the pH of the surface of water continues to be a contentious\ntopic in the physical chemistry of aqueous interfaces. Recent theoretical\nstudies have shown little or no preference for the proton to be at the surface\ncompared to the bulk\\cite{baer2014toward}. Using ab-initio molecular dynamics\nsimulations, we revisit the propensity of the excess proton for the air-water\ninterface with a particular focus on the role of instantaneous liquid\ninterfaces. We find a much a stronger propensity of the proton for the surface\nof water. The enhanced water structuring around the proton results in the\npresence of proton wires that run parallel to the surface as well as a\nhydrophobic environment made up of under-coordinated topological defect water\nmolecules, both of which create favorable conditions for proton confinement at\nthe surface. The Grotthuss mechanism within the structured water layer involves\na mixture of both concerted and closely spaced stepwise proton hops. The proton\nmakes excursions within the first solvation layer either in proximity to or\nalong the instantaneous interface.",
        "positive": "Anomalous relaxation in binary mixtures: a dynamic facilitation picture: Recent computational investigations in polymeric and non-polymeric binary\nmixtures have reported anomalous relaxation features when both components\nexhibit very different mobilities. Anomalous relaxation is characterized by\nsublinear power law behaviour for mean squared displacements, logarithmic decay\nin dynamic correlators, and a striking concave-to-convex crossover in the\nlatters by tuning the relevant control parameter, in analogy with predictions\nof the Mode Coupling Theory for state points close to higher-order transitions.\nWe present Monte Carlo simulations on a coarse-grained model for relaxation in\nbinary mixtures. The liquid structure is substituted by a three-dimensional\narray of cells. A spin variable is assigned to each cell, representing\nunexcited and excited local states of a mobility field. Changes in local\nmobility (spin flip) are permitted according to kinetic constraints determined\nby the mobilities of the neighbouring cells. We introduce two types of cells\n(``fast'' and ``slow'') with very different rates for spin flip. This\ncoarse-grained model qualitatively reproduces the mentioned anomalous\nrelaxation features observed for real binary mixtures."
    },
    {
        "anchor": "Formation of stable aggregates by fluid-assembled solid bridges: When a colloidal suspension is dried, capillary pressure may overwhelm\nrepulsive electrostatic forces, assembling aggregates that are out of thermal\nequilibrium. This poorly understood process confers cohesive strength to many\ngeological and industrial materials. Here we observe evaporation-driven\naggregation of natural and synthesized particulates, probe their stability\nunder rewetting, and measure bonding strength using an atomic force microscope.\nCohesion arises at a common length scale (~ 5 um), where interparticle\nattractive forces exceed particle weight. In polydisperse mixtures, smaller\nparticles condense within shrinking capillary bridges to build stabilizing\n'solid bridges' among larger grains. This dynamic repeats across scales forming\nremarkably strong, hierarchical clusters, whose cohesion derives from grain\nsize rather than mineralogy. Results may help to understand and control the\nstability of natural soils and synthetic materials.",
        "positive": "Active Brownian filaments with hydrodynamic interactions: conformations\n  and dynamics: The conformational and dynamical properties of active self-propelled\nfilaments/polymers are investigated in the presence of hydrodynamic\ninteractions by both, Brownian dynamics simulations and analytical theory.\nNumerically, a discrete linear chain composed of active Brownian particles is\nconsidered, analytically, a continuous linear semiflexible polymer with active\nvelocities changing diffusively. The force-free nature of active monomers is\naccounted for - no Stokeslet fluid flow induced by active forces - and higher\norder hydrodynamic multipole moments are neglected. The nonequilibrium\ncharacter of the active process implies a dependence of the stationary-state\nproperties on HI via the polymer relaxation times. In particular, at moderate\nactivities, HI lead to a substantial shrinkage of flexible and semiflexible\npolymers to an extent far beyond shrinkage of comparable free-draining\npolymers; even flexible HI-polymers shrink, while active free-draining polymers\nswell monotonically. Large activities imply a reswelling, however, to a less\nextent than for non-HI polymers, caused by the shorter polymer relaxation times\ndue to hydrodynamic interactions. The polymer mean square displacement is\nenhanced, and an activity-determined ballistic regime appears. Over a wide\nrange of time scales, flexible active polymers exhibit a hydrodynamically\ngoverned subdiffusive regime, with an exponent significantly smaller than that\nof the Rouse and Zimm models of passive polymers. Compared to simulations, the\napproximate analytical approach predicts a weaker hydrodynamic effect."
    },
    {
        "anchor": "Aging of a Homogeneously Quenched Colloidal Glass-forming Liquid: The non-equilibrium self-consistent generalized Langevin equation theory of\ncolloid dynamics is used to describe the non-stationary aging processes\noccurring in a suddenly quenched model colloidal liquid with hard-sphere plus\nshort-ranged attractive interactions, whose static structure factor and van\nHove function evolve irreversibly from the initial conditions before the quench\nto a final, dynamically arrested state. The comparison of our numerical results\nwith available simulation data are highly encouraging.",
        "positive": "Mechanisms for recirculation cells in granular flows in rotating\n  cylindrical rough tumblers: Friction at the endwalls of partially-filled horizontal rotating tumblers\ninduces curvature and axial drift of particle trajectories in the surface\nflowing layer. Here we describe the results of a detailed discrete element\nmethod study of the dry granular flow of monodisperse particles in\nthreedimensional cylindrical tumblers with endwalls and cylindrical wall that\ncan be either smooth or rough. Endwall roughness induces more curved particle\ntrajectories, while a smooth cylindrical wall enhances drift near the endwall.\nThis drift induces recirculation cells near the endwall. The use of mixed\nroughness (cylindrical wall and endwalls having different roughness) shows the\ninfluence of each wall on the drift and curvature of particle trajectories as\nwell as the modification of the free surface topography. The effects act in\nopposite directions and have variable magnitude along the length of the tumbler\nsuch that their sum determines both direction of net drift and the\nrecirculation cells. Near the endwalls, the dominant effect is always the\nendwall effect, and the axial drift for surface particles is toward the\nendwalls. For long enough tumblers, a counter-rotating cell occurs adjacent to\neach of the endwall cells having a surface drift toward the center because the\ncylindrical wall effect is dominant there. These cells are not dynamically\ncoupled with the two endwall cells. The competition between the drifts induced\nby the endwalls and the cylindrical wall determines the width and drift\namplitude for both types of cells."
    },
    {
        "anchor": "The role of grain dynamics in determining the onset of sediment\n  transport: Sediment transport occurs when the nondimensional fluid shear stress $\\Theta$\nat the bed surface exceeds a minimum value $\\Theta_c$. A large collection of\ndata, known as the Shields curve, shows that $\\Theta_c$ is primarily a function\nof the shear Reynolds number ${\\rm{Re}}_*$. It is commonly assumed that\n$\\Theta>\\Theta_c({\\rm{Re}}_*)$ occurs when the ${\\rm Re}_*$-dependent fluid\nforces are too large to maintain static equilibrium for a typical surface\ngrain. A complimentary approach, which remains relatively unexplored, is to\nidentify $\\Theta_c({\\rm{Re}}_*)$ as the applied shear stress at which grains\ncannot stop moving. With respect to grain dynamics, ${\\rm{Re}}_*$ can be viewed\nas the viscous time scale for a grain to equilibrate to the fluid flow divided\nby the typical time for the fluid force to accelerate a grain over the\ncharacteristic bed roughness. We performed simulations of granular beds sheared\nby a model fluid, varying only these two time scales. We find that the critical\nShields number $\\Theta_c({\\rm Re}_*)$ obtained from the model mimics the\nShields curve and is insensitive to the grain properties, the model fluid flow,\nand the form of the drag law. Quantitative discrepancies between the model\nresults and the Shields curve are consistent with previous calculations of lift\nforces at varying ${\\rm Re}_*$. Grains at low ${\\rm Re}_*$ find more stable\nconfigurations than those at high ${\\rm{Re}}_*$ due to differences in the grain\nreorganization dynamics. Thus, instead of focusing on mechanical equilibrium of\na typical grain at the bed surface, $\\Theta_c({\\rm{Re}}_*)$ may be better\ndescribed by the stress at which mobile grains cannot find a stable\nconfiguration and stop moving.",
        "positive": "Pores in Bilayer Membranes of Amphiphilic Molecules: Coarse-Grained\n  Molecular Dynamics Simulations Compared with Simple Mesoscopic Models: We investigate pores in fluid membranes by molecular dynamics simulations of\nan amphiphile-solvent mixture, using a molecular coarse-grained model. The\namphiphilic membranes self-assemble into a lamellar stack of amphiphilic\nbilayers separated by solvent layers. We focus on the particular case of\ntension less membranes, in which pores spontaneously appear because of thermal\nfluctuations. Their spatial distribution is similar to that of a random set of\nrepulsive hard discs. The size and shape distribution of individual pores can\nbe described satisfactorily by a simple mesoscopic model, which accounts only\nfor a pore independent core energy and a line tension penalty at the pore\nedges. In particular, the pores are not circular: their shapes are fractal and\nhave the same characteristics as those of two dimensional ring polymers.\nFinally, we study the size-fluctuation dynamics of the pores, and compare the\ntime evolution of their contour length to a random walk in a linear potential."
    },
    {
        "anchor": "Polymer translocation into cavities: Effects of confinement geometry,\n  crowding and bending rigidity on the free energy: Monte Carlo simulations are used to study the translocation of a polymer into\na cavity. Modeling the polymer as a hard-sphere chain with a length up to N=601\nmonomers, we use a multiple-histogram method to measure the variation of the\nconformational free energy of the polymer with respect to the number of\ntranslocated monomers. The resulting free-energy functions are then used to\nobtain the confinement free energy for the translocated portion of the polymer.\nWe characterize the confinement free energy for a flexible polymer in cavities\nwith constant cross-sectional area A for various cavity shapes (cylindrical,\nrectangular and triangular) as well as for tapered cavities with pyramidal and\nconical shape. The scaling of the free energy with cavity volume and\ntranslocated polymer subchain length is generally consistent with predictions\nfrom simple scaling arguments, with small deviations in the scaling exponents\nlikely due to finite-size effects. The confinement free energy depends strongly\non cavity shape anisometry and is a minimum for an isometric cavity shape with\na length/width ratio of unity. For translocation into infinitely long cones,\nthe scaling of the free energy with taper angle is consistent with a\ntheoretical prediction employing the blob model. We also examine the effects of\npolymer bending rigidity on the translocation free energy for cylindrical\ncavities. For isometric cavities, the observed scaling behaviour is in partial\nagreement with theoretical predictions. In addition, translocation into highly\nanisometric cylindrical cavities leads to a multi-stage folding process for\nstiff polymers. Finally, we examine the effects of crowding agents inside the\ncavity. We find that the confinement free energy increases with crowder\ndensity. At constant packing fraction the magnitude of this effect lessens with\nincreasing crowder size for crowder/monomer size ratio$\\geq$ 1.",
        "positive": "Unstable topography of biphasic surfactant monolayers: We study the conformation of a heterogeneous surfactant monolayer at a\nfluid-fluid interface, near a boundary between two lateral regions of differing\nelastic properties. The monolayer attains a conformation of shallow, steep\n`mesas' with a height difference of up to 10 nm. If the monolayer is\nprogressively compressed (e.g. in a Langmuir trough), the profile develops\noverhangs and finally becomes unstable at a surface tension of about K(delta\nc_0)^2, where (delta c_0) is the difference in spontaneous curvature and K a\nbending stiffness. We discuss the relevance of this instability to recently\nobserved folding behavior in lung surfactant monolayers, and to the absence of\ndomain structures in films separating oil and water in emulsions."
    },
    {
        "anchor": "Computer simulations of colloidal transport on a patterned magnetic\n  substrate: We study the transport of paramagnetic colloidal particles on a patterned\nmagnetic substrate with kinetic Monte Carlo and Brownian dynamics computer\nsimulations. The planar substrate is decorated with point dipoles in either\nparallel or zigzag stripe arrangements and exposed to an additional external\nmagnetic field that oscillates in time. For the case of parallel stripes we\nfind that the magnitude and direction of the particle current is controlled by\nthe tilt angle of the external magnetic field. The effect is reliably obtained\nin a wide range of ratios between temperature and magnetic permeability.\nParticle transport is achieved only when the period of oscillation of the\nexternal field is greater than a critical value. For the case of zigzag stripes\na current is obtained using an oscillating external field normal to the\nsubstrate. In this case, transport is only possible in the vertex of the\nzigzag, giving rise to a narrow stream of particles. The magnitude and\ndirection of the particle current are found to be controlled by a combination\nof the zigzag angle and the distance of the colloids from the substrate.\nMetropolis Monte Carlo and Brownian dynamics simulations predict results that\nare in good agreement with each other. Using kinetic Monte Carlo we find that\nat high density the particle transport is hindered by jamming.",
        "positive": "Crystal Growth of Isotactic Polystyrene in Ultrathin Films : Film\n  Thickness Dependence: The film thickness dependence of crystal growth is investigated for isotactic\npolystyrene (it-PS) in thin films, the thickness of which is from 20nm down to\n4nm. The single crystals of it-PS grown at 180 in the ultrathin films show the\nmorphology typical in the diffusion-controlled growth: dense branching\nmorphology (DBM), fractal seeweed (FS). The characteristic length of the\nmorphology, i.e. the width of the branch, increases with decreasing film\nthickness. The thickness dependence of the growth rate of crystals shows a\ncrossover around the lamellar thickness of the crystal, 8 nm. The thickness\ndependences of the growth rate and morphology are discussed in terms of the\ndiffusion of chain molecules in thin films."
    },
    {
        "anchor": "Model of Controlled Synthesis of Uniform Colloid Particles: Cadmium\n  Sulfide: The recently developed two-stage growth model of synthesis of monodispersed\npolycrystalline colloidal particles is utilized and improved to explain growth\nof uniform cadmium sulfide spheres. The model accounts for the coupled\nprocesses of nucleation, which yields nanocrystalline precursors, and\naggregation of these subunits to form the final particles. The key parameters\nhave been identified that control the size selection and uniformity of the CdS\nspheres, as well as the dynamics of the process. This approach can be used to\ngenerally describe the formation of monodispersed colloids by precipitation\nfrom homogeneous solutions.",
        "positive": "Patterns and Collective Behavior in Granular Media: Theoretical Concepts: Granular materials are ubiquitous in our daily lives. While they have been a\nsubject of intensive engineering research for centuries, in the last decade\ngranular matter attracted significant attention of physicists. Yet despite a\nmajor efforts by many groups, the theoretical description of granular systems\nremains largely a plethora of different, often contradicting concepts and\napproaches. Authors give an overview of various theoretical models emerged in\nthe physics of granular matter, with the focus on the onset of collective\nbehavior and pattern formation. Their aim is two-fold: to identify general\nprinciples common for granular systems and other complex non-equilibrium\nsystems, and to elucidate important distinctions between collective behavior in\ngranular and continuum pattern-forming systems."
    },
    {
        "anchor": "Cross-link governed dynamics of biopolymer networks: Cytoskeletal networks of biopolymers are cross-linked by a variety of\nproteins. Experiments have shown that dynamic cross-linking with physiological\nlinker proteins leads to complex stress relaxation and enables network flow at\nlong times. We present a model for the mechanical properties of transient\nnetworks. By a combination of simulations and analytical techniques we show\nthat a single microscopic timescale for cross-linker unbinding leads to a broad\nspectrum of macroscopic relaxation times, resulting in a weak power-law\ndependence of the shear modulus on frequency. By performing rheological\nexperiments, we demonstrate that our model quantitatively describes the\nfrequency behavior of actin network cross-linked with $\\alpha$-Actinin-$4$ over\nfour decades in frequency.",
        "positive": "Aggregation kinetics of stiff polyelectrolytes in the presence of\n  multivalent salt: Using molecular dynamics simulations, the kinetics of bundle formation for\nstiff polyelectrolytes such as actin is studied in the solution of multivalent\nsalt. The dominant kinetic mode of aggregation is found to be the case of one\nend of one rod meeting others at right angle due to electrostatic interactions.\nThe kinetic pathway to bundle formation involves a hierarchical structure of\nsmall clusters forming initially and then feeding into larger clusters, which\nis reminiscent of the flocculation dynamics of colloids. For the first few\ncluster sizes, the Smoluchowski formula for the time evolution of the cluster\nsize gives a reasonable account for the results of our simulation without a\nsingle fitting parameter. The description using Smoluchowski formula provides\nevidence for the aggregation time scale to be controlled by diffusion, with no\nappreciable energy barrier to overcome."
    },
    {
        "anchor": "A Field-Theoretic Model for Chemotaxis in Run and Tumble Particles: In this paper we develop a field-theoretic description for run and tumble\nchemotaxis, based on a density functional description of crystalline materials\nmodified to capture orientational ordering. We show that this framework, with\nits in-built multi-particle interactions, soft-core repulsion and elasticity is\nideal for describing continuum collective phases with particle resolution, but\non diffusive timescales. We show that our model exhibits particle aggregation\nin an externally imposed constant attractant field, as is observed for\nphototactic or thermotactic agents. We also show that this model captures\nparticle aggregation through self-chemotaxis, an important mechanism that aids\nquorum dependent cellular interactions.",
        "positive": "Morphology and flow patterns in highly asymmetric active emulsions: We investigate numerically, by a hybrid lattice Boltzmann method, the\nmorphology and the dynamics of an emulsion made of a polar active gel,\ncontractile or extensile, and an isotropic passive fluid. We focus on the case\nof a highly off-symmetric ratio between the active and passive components. In\nabsence of any activity we observe an hexatic-ordered droplets phase, with some\ndefects in the layout. We study how the morphology of the system is affected by\nactivity both in the contractile and extensile case. In the extensile case a\nsmall amount of activity favors the elimination of defects in the array of\ndroplets, while at higher activities, first aster-like rotating droplets\nappear, and then a disordered pattern occurs. In the contractile case, at\nsufficiently high values of activity, elongated structures are formed. Energy\nand enstrophy behavior mark the transitions between the different regimes."
    },
    {
        "anchor": "Quantifying Wetting Dynamics with Triboelectrification: Wetting is often perceived as an intrinsic surface property of materials, but\ndetermining its evolution is complicated by its complex dependence on roughness\nacross the scales. The Wenzel state, where liquids have intimate contact with\nthe rough substrate, and the Cassie-Baxter state, where liquids sit onto air\npockets formed between asperities, are only two states among the plethora of\nwetting behaviors. Furthermore, transitions from the Cassie-Baxter to the\nWenzel state dictate completely different surface performance, such as\nanti-contamination, anti-icing, drag reduction etc.; however, little is known\nabout how transition occurs during time between the several wetting modes. In\nthis paper, we show that wetting dynamics can be accurately quantified and\ntracked using solid-liquid triboelectrification. Theoretical underpinning\nreveals how surface micro-/nano-geometries regulate stability/infiltration,\nalso demonstrating the generality of our theoretical approach in understanding\nwetting transitions.",
        "positive": "Anomalous cooling and overcooling of active systems: The phenomenon that a system at a hot temperature cools faster than at a warm\ntemperature, referred to as the Mpemba effect, has been recently realized for\ntrapped colloids. Here, we investigate the cooling and heating process of a\nself-propelling active colloid using numerical simulations and theoretical\ncalculations with a model that can directly be tested in experiments. Upon\ncooling the particles' active motion induces a Mpemba effect. Transiently the\nsystem can even exhibit smaller temperatures than its final temperature, a\nsurprising phenomenon which we refer to as activity-induced overcooling."
    },
    {
        "anchor": "Self-propulsion of an active polar drop: We investigate the self-propulsive motion of a drop containing an active\npolar field. The drop demonstrates spontaneous symmetry breaking from a uniform\norientational order into a splay or bend instability depending on the types of\nactive stress, namely, contractile or extensile, respectively. We develop the\nanalytical theory of the mechanism of this instability, which has been observed\nonly in numerical simulations. We show that both contractile and extensile\nactive stress result in the instability and self-propulsive motion. We also\ndiscuss asymmetry between contractile and extensile stress, and show that\nextensile active stress generates chaotic motion even under a simple model of\nthe polarity field coupled with motion and deformation of the drop.",
        "positive": "Reversible heating in electric double layer capacitors: A detailed comparison is made between different viewpoints on reversible\nheating in electric double layer capacitors. We show in the limit of slow\ncharging that a combined Poisson-Nernst-Planck and heat equation, first studied\nby d'Entremont and Pilon [J. Power Sources {\\bf 246}, 887 (2014)], recovers the\ntemperature changes as predicted by the thermodynamic identity of Janssen,\nH\\\"{a}rtel, and van Roij [Phys. Rev. Lett. {\\bf 113}, 268501 (2014)], and\ndisagrees with the approximative model of Schiffer, Linzen, and Sauer [J. Power\nSources {\\bf 160}, 765 (2006)] that predominates the literature."
    },
    {
        "anchor": "Continuum theory of swelling material surfaces with applications to\n  thermo-responsive gel membranes and surface mass transport: Soft membranes are commonly employed in shape-morphing applications, where\nthe material is programmed to achieve a target shape upon activation by an\nexternal trigger, and as coating layers that alter the surface characteristics\nof bulk materials, such as the properties of spreading and absorption of\nliquids. In particular, polymer gel membranes experience swelling or shrinking\nwhen their solvent content change, and the non-homogeneous swelling field may\nbe exploited to control their shape. Here, we develop a theory of swelling\nmaterial surfaces to model polymer gel membranes and demonstrate its features\nby numerically studying applications in the contexts of biomedicine,\nmicro-motility, and coating technology. We also specialize the theory to\nthermo-responsive gels, which are made of polymers that change their affinity\nwith a solvent when temperature varies.",
        "positive": "Ostwald-like ripening in the two-dimensional clustering of passive\n  particles induced by swimming bacteria: Clustering passive particles by active agents is a promising route for\nfabrication of colloidal structures. Here, we report the dynamic clustering of\nmicrometric beads in a suspension of motile bacteria. We characterize the\ncoarsening dynamics for various bead sizes, surface fractions and bacterial\nconcentrations. We show that the time scale $\\tau$ for the onset of clustering\nis governed by the time of first encounter of diffusing beads. At large time\n($t \\gg \\tau$), we observe a robust cluster growth as $t^{1/3}$, similar to the\nOstwald ripening mechanism. From bead tracking measurements, we extract the\nshort-range bacteria-induced attractive force at the origin of this clustering."
    },
    {
        "anchor": "Yielding behavior of glasses under asymmetric cyclic deformation: We consider the yielding behaviour of a model glass subjected to asymmetric\ncyclic shear deformation, wherein the applied strain varies between 0 and a\nmaximum value $\\gamma_{\\rm max}$, and study its dependence on the degree of\nannealing of the glass and system size. The yielding behaviour of well annealed\nglasses (unlike poorly annealed glasses) display striking differences from the\nsymmetric case, with the emergence of an intermediate strain regime with\nsubstantial plasticity but no yielding. The observed behaviour is\nsatisfactorily captured by a recently proposed model. For larger system sizes,\nthe intermediate strain regime narrows, leading to a remarkable reversal of\nyield strain with annealing.",
        "positive": "Spatial structure of disordered media: Unravelling the mechanical\n  significance of disorder in granular materials: For two decades now, the importance of microstructure in the mechanical\nbehaviour of a large collection of grains has been a topic of intense research.\nMany approaches have been developed to study the microstructure in granular\nmaterials, based on local or mesoscopic measures or using ideas from diverse\nfields like percolation theory, complex networks and persistent homology.\nHowever, we do not fully understand the role of microstructure in the\nmechanical behaviour of simple and commonplace packings like a pile of sand or\nbox of grains. Here, by characterizing the spatial variation of local\nmicrostructure, we uncover intriguing large-scale spatial patterns in particle\npackings deposited under the influence of gravity. We detail the emergence of\nthese patterns, and provide a unified fundamental explanation of classic and\npuzzling mechanical behaviours of granular materials like central stress\nminimum and Janssen effect. Further, we show the striking dependence of spatial\nstructure on the history of preparation, size distribution of particles and\nboundary conditions. Our study reveals the existence of global spatial\nstructure in a locally disordered media, and elucidates its significance in the\nmechanical behaviour of granular materials."
    },
    {
        "anchor": "Observation of strongly heterogeneous dynamics at the depinning\n  transition in a colloidal glass: We study experimentally the origin of heterogeneous dynamics in strongly\ndriven glass-forming systems. Thereto, we apply a well-defined force with a\nlaser line trap on individual colloidal polystyrene probe particles seeded in\nan emulsion glass composed of droplets of the same size. Fluid and glass states\ncan be probed. We monitor the trajectories of the probe and measure\ndisplacements and their distributions. Our experiments reveal intermittent\ndynamics around a depinning transition at a threshold force. For smaller\nforces, linear response connects mean displacement and quiescent mean squared\ndisplacement. Mode coupling theory calculations rationalize the observations.",
        "positive": "Curvature dependence of the interfacial tensions around nanoscale\n  cylinder: Young's equation still holds: By extending the theoretical framework derived in our previous study [Y.\nImaizumi et al., J. Chem. Phys. 153, 034701 (2020)], we successfully calculated\nthe solid-liquid (SL) and solid-vapor (SV) interfacial tensions of a simple\nLennard-Jones fluid around solid cylinders with nanometer-scale diameters from\nsingle equilibrium molecular dynamics (MD) systems, in which a solid cylinder\nwas vertically immersed into a liquid pool. The SL and SV interfacial tensions\n$\\gamma_\\mathrm{SL} - \\gamma_\\mathrm{S0}$ and $\\gamma_\\mathrm{SV} -\n\\gamma_\\mathrm{S0}$ relative to that for bare solid surface\n$\\gamma_\\mathrm{S0}$, respectively were obtained by simple force balance\nrelations on fluid-containing control volumes set around the bottom and top of\nthe solid cylinder, which are subject to the fluid stress and the force from\nthe solid. % The theoretical contact angle calculated by Young's equation using\nthese interfacial tensions agreed well with the apparent contact angle\nestimated by the analytical solution fitted to the meniscus shape, showing that\nYoung's equation holds even for the menisci around solids with nanoscale\ncurvature. % We have also found that the curvature effect on the contact angle\nwas surprisingly small while it was indeed large on the local forces exerted on\nthe solid cylinder near the contact line. In addition, the present results\nshowed that the curvature dependence of the SL and SV interfacial free\nenergies, which are the interfacial tensions, is different from that of the\ncorresponding interfacial potential energies."
    },
    {
        "anchor": "The smooth cut-off Hierarchical Reference Theory of fluids: We provide a comprehensive presentation of the Hierarchical Reference Theory\n(HRT) in the smooth cut-off formulation. A simple and self-consistent\nderivation of the hierarchy of differential equations is supplemented by a\ncomparison with the known sharp cut-off HRT. Then, the theory is applied to a\nhard core Yukawa fluid (HCYF): a closure, based on a mean spherical\napproximation ansatz, is studied in detail and its intriguing relationship to\nthe self consistent Ornstein-Zernike approximation is discussed. The asymptotic\nproperties, close to the critical point are investigated and compared to the\nrenormalization group results both above and below the critical temperature.\nThe HRT free energy is always a convex function of the density, leading to flat\nisotherms in the two-phase region with a finite compressibility at coexistence.\nThis makes HRT the sole liquid-state theory able to obtain directly fluid-fluid\nphase equilibrium without resorting to the Maxwell construction. The way the\nmean field free energy is modified due to the inclusion of density fluctuations\nsuggests how to identify the spinodal curve. Thermodynamic properties and\ncorrelation functions of the HCYF are investigated for three values of the\ninverse Yukawa range: z=1.8, z=4 and z=7 where Monte Carlo simulations are\navailable. The stability of the liquid-vapor critical point with respect to\nfreezing is also studied.",
        "positive": "Active Brownian motion in a narrow channel: We review recent advances in rectification control of artificial\nmicroswimmers, also known as Janus particles, diffusing along narrow,\nperiodically corrugated channels. The swimmer self-propulsion mechanism is\nmodeled so as to incorporate a nonzero torque (propulsion chirality). We first\nsummarize the effects of chirality on the autonomous current of microswimmers\nfreely diffusing in channels of different geometries. In particular, left-right\nand upside-down asymmetric channels are shown to exhibit different transport\nproperties. We then report new results on the dependence of the diffusivity of\nchiral microswimmers on the channel geometry and their own self-propulsion\nmechanism. The self-propulsion torque turns out to play a key role as a\ntransport control parameter."
    },
    {
        "anchor": "Generalized coherent state representation of Bose-Einstein condensates: We show that the quantum many-body state of Bose-Einstein condensates (BEC)\nconsistent with the time-dependent Hartree-Fock-Bogoliubov (TDHFB) equations is\na generalized coherent state (GCS). At zero temerature, the non-condensate\ndensity and the anomalous non-condensate correlation are not independent,\nallowing us to elimiate one of the three variables in the TDHFB.",
        "positive": "Transient dynamics of a colloidal particle driven through a viscoelastic\n  fluid: We experimentally study the transient motion of a colloidal particle actively\ndragged by an optical trap through different viscoelastic fluids (wormlike\nmicelles, polymer solutions, and entangled $\\lambda$-phage DNA). We observe\nthat, after sudden removal of the moving trap, the particle recoils due to the\nrecovery of the deformed fluid microstructure. We find that the transient\ndynamics of the particle proceeds via a double exponential relaxation, whose\nrelaxation times remain independent of the initial particle velocity whereas\ntheir amplitudes strongly depend on it. While the fastest relaxation mirrors\nthe viscous damping of the particle by the solvent, the slow relaxation results\nfrom the recovery of the strained viscoelastic matrix. We show that this\ntransient information, which has no counterpart in Newtonian fluids, can be\nexploited to investigate linear and nonlinear rheological properties of the\nembedding fluid, thus providing a novel method to perform transient rheology at\nthe micron-scale."
    },
    {
        "anchor": "Minimal design of the elephant trunk as an active filament: One of the key problems in active materials is the control of shape through\nactuation. A fascinating example of such control is the elephant trunk, a long,\nmuscular, and extremely dexterous organ with multiple vital functions. The\nelephant trunk is an object of fascination for biologists, physicists, and\nchildren alike. Its versatility relies on the intricate interplay of multiple\nunique physical mechanisms and biological design principles. Here we explore\nthese principles using the theory of active filaments and build, theoretically,\ncomputationally, and experimentally, a minimal model that explains and\naccomplishes some of the spectacular features of the elephant trunk.",
        "positive": "Adhesion of fluid infused silicone elastomer to glass: Elastomers swollen with non-polar fluids show potential as anti-adhesive\nmaterials. We study the effect of oil fraction and contact time on the adhesion\nbetween swollen spherical probes of PDMS (polydimethylsiloxane) and flat glass\nsurfaces. The PDMS probes are swollen with pre-determined amount of 10 cSt\nsilicone oil to span the range where the PDMS is fluid free (via solvent\nextraction) up to the limit where it is oil saturated. Probe tack measurements\nshow that adhesion decreases rapidly with an increase in oil fraction. The\ndecrease in adhesion is attributed to excess oil present at the PDMS-air\ninterface. Contact angle measurements and optical microscopy images support\nthis observation. Adhesion also increases with contact time for a given oil\nfraction. The increase in adhesion with contact time can be interpreted through\ndifferent competing mechanisms that depend on the oil fraction where the\ndominant mechanism changes from extracted to fully swollen PDMS. For partially\nswollen PDMS, we observe that adhesion initially increases because of\nviscoelastic relaxation and at long times increases because of contact aging.\nIn contrast, adhesion between fully swollen PDMS and glass barely increases\nover time and is mainly due to capillary forces. While the relaxation of PDMS\nin contact is well-described by a visco-poroelastic model, we do not see\nevidence that poroelastic relaxation of the PDMS contributes to an increase of\nadhesion with glass whether it is partially or fully swollen."
    },
    {
        "anchor": "Irreversibility and Polymer Adsorption: Physisorption or chemisorption from dilute polymer solutions often entails\nirreversible polymer-surface bonding. We present a theory of the\nnon-equilibrium layers which result. While the density profile and loop\ndistribution are the same as for equilibrium layers, the final layer comprises\na tightly bound inner part plus an outer part whose chains make only fN surface\ncontacts where N is chain length. The contact fractions f follow a broad\ndistribution, P(f) ~ f^{-4/5}, in rather close agreement with strong\nphysisorption experiments [H. M. Schneider et al, Langmuir v.12, p.994 (1996)].",
        "positive": "Fluctuations of topological disclination lines in nematics:\n  renormalization of the string model: The fluctuation eigenmode problem of the nematic topological disclination\nline with strength $\\pm 1/2$ is solved for the complete nematic tensor order\nparameter. The line tension concept of a defect line is assessed, the line\ntension is properly defined. Exact relaxation rates and thermal amplitudes of\nthe fluctuations are determined. It is shown that within the simple string\nmodel of the defect line the amplitude of its thermal fluctuations is\nsignificantly underestimated due to the neglect of higher radial modes. The\nextent of universality of the results concerning other systems possessing line\ndefects is discussed."
    },
    {
        "anchor": "Monte Carlo simulations reveal the straightening up of an end-grafted\n  flexible chain with a rigid side chain: We have studied the conformational properties of a flexible end-grafted chain\n(length $N$) with a rigid side chain (length $S$) by means of Monte Carlo\nsimulations. Depending on the lengths $N$ and $S$ and the branching site, $b$,\nwe observe a considerable straightening of the flexible backbone as quantified\nvia the gyration tensor. For $b=N$, i.e. when attaching the side chain to the\nfree end of the flexible backbone, the effect was strongest.",
        "positive": "Brittle fracture of polymer transient networks: We study the fracture of reversible double transient networks, constituted of\nwater suspensions of entangled surfactant wormlike micelles reversibly linked\nby various amounts of telechelic polymers. We provide a state diagram that\ndelineates the regime of fracture without necking of the filament from the\nregime where no fracture or break-up has been observed. We show that filaments\nfracture when stretched at a rate larger than the inverse of the slowest\nrelaxation time of the networks. We quantitatively demonstrate that dissipation\nprocesses are not relevant in our experimental conditions and that, depending\non the density of nodes in the networks, fracture occurs in the linear\nviscoelastic regime or in a non-linear regime. In addition, analysis of the\ncrack opening profiles indicates deviations from a parabolic shape close to the\ncrack tip for weakly connected networks. We demonstrate a direct correlation\nbetween the amplitude of the deviation from the parabolic shape and the amount\nof non linear viscoelasticity."
    },
    {
        "anchor": "Diffusion-Oscillatory Dynamics in Liquid Water on Data of Dielectric\n  Spectroscopy: When analyzing the broadband absorption spectrum of liquid water (10^10 -\n10^13 Hz), we find its relaxation-resonance features to be an indication of\nFrenkel's translation-oscillation motion of particles, which is fundamentally\ninherent to liquids. We have developed a model of water structure, of which the\ndynamics is due to diffusion of particles, neutral H2O molecules and H3O+ and\nOH- ions - with their periodic localizations and mutual transformations. This\nmodel establishes for the first time a link between the dc conductivity, the\nDebye and the high frequency sub-Debye relaxations and the infrared absorption\npeak at 180 cm-1. The model reveals the characteristic times of the\nrelaxations, 50 ps and 3 ps, as the lifetimes of water molecules and water\nions, respectively. The model sheds light on the anomalous mobility of a proton\nand casts doubt on the long lifetime of a water molecule, 10 hours, commonly\nassociated with autoionization.",
        "positive": "Lyapunov vectors and excited energy levels of the directed polymer in\n  random media: The scaling behavior of the excited energy levels of the directed polymer in\nrandom media is analyzed numerically. We find that the spatial correlations of\npolymer energies scale as $\\sim k^{-\\delta}$ for small enough wavenumbers $k$\nwith a nontrivial exponent $\\delta \\approx 1.3$. The equivalence between the\nstochastic-field equation that describes the partition function of the directed\npolymer and that governing the time evolution of infinitesimal perturbations in\nspace-time chaos is exploited to connect this exponent $\\delta$ with the\nspatial correlations of Lyapunov vectors reported in the literature. The\nrelevance of our results for other problems involving optimization in random\nsystems is discussed."
    },
    {
        "anchor": "Tangential diffusion and motility-induced mixing transition in\n  exponentially growing multicellular spheroids: Growth is a known driver of cellular dynamics in a range of dense aggregates\nfrom bacterial colonies to developing tissues to tumors. Hence, universal\nphysical principles underlying these dynamics are of great interdisciplinary\ninterest. Here, we study the emergent dynamics arising from the interplay of\ngrowth, steric repulsion and motility in a minimal agent-based model of\nexponentially growing three-dimensional spheroids. Our results show that,\nwithout cell motility, deterministic motion caused by overall volume expansion\ndominates the dynamics of individual cells in the radial direction, while\ngrowth and division lead to cellular-scale diffusive motion in the tangential\ndirection, whose magnitude is largely independent of expansion velocity.\nDespite this small-scale diffusion, we show that cell lineages are subject to\nconfinement in their local environment, quenching weak cell motility. At higher\nmotility, we find a transient regime of tangential superdiffusivity, which is\naccompanied by global mixing of cells. A quantitative analysis reveals a\ndiverging mixing time scale at the transition, reminiscent of glassy dynamics.\nOur study highlights the complex interaction of local cell division and\nmotility with global expansion, mediated exclusively by mechanics. The\nobservations may serve as a baseline for the identification of phenomena caused\nby additional biological mechanisms in experiments on tissue spheroids, which\nhave become a popular model system in biophysics and other fields. The mixing\ndynamics might also be relevant for competition or tumor progression.",
        "positive": "Disclination-mediated thermo-optical response in nematic glass sheets: Nematic solids respond strongly to changes in ambient heat or light,\nsignificantly differently parallel and perpendicular to the director. This\nphenomenon is well characterized for uniform director fields, but not for\ndefect textures. We analyze the elastic ground states of a nematic glass in the\nmembrane approximation as a function of temperature for some disclination\ndefects with an eye towards reversibly inducing three-dimensional shapes from\nflat sheets of material, at the nano-scale all the way to macroscopic objects,\nincluding non-developable surfaces. The latter offers a new paradigm to\nactuation via switchable stretch in thin systems."
    },
    {
        "anchor": "Resonance Superfluidity: Renormalization of Resonance Scattering Theory: We derive a theory of superfluidity for a dilute Fermi gas that is valid when\nscattering resonances are present. The treatment of a resonance in many-body\natomic physics requires a novel mean-field approach starting from an\nunconventional microscopic Hamiltonian. The mean-field equations incorporate\nthe microscopic scattering physics, and the solutions to these equations\nreproduce the energy-dependent scattering properties. This theory describes the\nhigh-$T_c$ behavior of the system, and predicts a value of $T_c$ which is a\nsignificant fraction of the Fermi temperature. It is shown that this novel\nmean-field approach does not break down for typical experimental circumstances,\neven at detunings close to resonance. As an example of the application of our\ntheory we investigate the feasibility for achieving superfluidity in an\nultracold gas of fermionic $^6$Li.",
        "positive": "Analytical First Derivatives of the RE-squared Interaction Potential: We derive exact expressions for the forces and torques between biaxial\nmolecules interacting via the RE-squared potential, a recent variant of the\nGay-Berne potential. Moreover, efficient routines have been provided for rigid\nbody MD simulations, resulting in 1.6 times speedup compared to the two-point\nfinite difference approach. It has also been shown that the time cost of a MD\nsimulation will be almost equal to a similar MC simulation, making use of the\nprovided routines."
    },
    {
        "anchor": "External-field-induced tricritical point in a fluctuation-driven\n  nematic-smectic-A transition: We study theoretically the effect of an external field on the\nnematic-smectic-A (NA) transition close to the tricritical point, where\nfluctuation effects govern the qualitative behavior of the transition. An\nexternal field suppresses nematic director fluctuations, by making them\nmassive. For a fluctuation-driven first-order transition, we show that an\nexternal field can drive the transition second-order. In an appropriate liquid\ncrystal system, we predict the required magnetic field to be of order 10 T. The\nequivalent electric field is of order $1 V/\\mu m$.",
        "positive": "Generic theory of colloidal transport: We discuss the motion of colloidal particles relative to a two component\nfluid consisting of solvent and solute. Particle motion can result from (i) net\nbody forces on the particle due to external fields such as gravity; (ii) slip\nvelocities on the particle surface due to surface dissipative phenomena. The\nperturbations of the hydrodynamic flow field exhibits characteristic\ndifferences in cases (i) and (ii) which reflect different patterns of momentum\nflux corresponding to the existence of net forces, force dipoles or force\nquadrupoles. In the absence of external fields, gradients of concentration or\npressure do not generate net forces on a colloidal particle. Such gradients can\nnevertheless induce relative motion between particle and fluid. We present a\ngeneric description of surface dissipative phenomena based on the linear\nresponse of surface fluxes driven by conjugate surface forces. In this\nframework we discuss different transport scenarios including self-propulsion\nvia surface slip that is induced by active processes on the particle surface.\nWe clarify the nature of force balances in such situations."
    },
    {
        "anchor": "Gel-Electrophoresis and Diffusion of Ring-Shaped DNA: A model for the motion of ring-shaped DNA in a gel is introduced and studied\nby numerical simulations and a mean-field approximation. The ring motion is\nmediated by finger-shaped loops (hernias) that move in an amoeba-like fashion\naround the gel obstructions. This constitutes an extension of previous\nreptation tube treatments. It is shown that tension is essential for describing\nthe dynamics in the presence of hernias. It is included in the model as long\nrange interactions over stretched DNA regions. The mobility of ring-shaped DNA\nis found to saturate much as in the well-studied case of linear DNA.\nExperiments in polymer gels, however, show that the mobility drops\nexponentially with the DNA ring size. This is commonly attributed to\ndangling-ends in the gel that can impale the ring. The predictions of the\npresent model are expected to apply to artificial 2D obstacle arrays (W.D.\nVolkmuth, R.H. Austin, Nature 358,600 (1992)) which have no dangling-ends. In\nthe zero-field case an exact solution of the model steady-state is obtained,\nand quantities such as the average ring size are calculated. An approximate\ntreatment of the ring dynamics is given, and the diffusion coefficient is\nderived. The model is also discussed in the context of spontaneous symmetry\nbreaking in one dimension.",
        "positive": "Relaxation in homogeneous and non-homogeneous polarized systems. A\n  mesoscopic entropy approach: The dynamics of a degree of freedom associated to an axial vector in contact\nwith a heat bath is decribed by means of a probability distribution function\nobeying a Fokker-Planck equation. The equation is derived by using mesoscopic\nnon-equilibrium thermodynamics and permits a formulation of a dynamical theory\nfor the axial degree of freedom (orientation, polarization) and its associated\norder parameter. The theory is used to describe dielectric relaxation in\nhomogeneous and non-homogeneous systems in the presence of strong electric\nfields. In the homogeneous case, we obtain the dependence of the relaxation\ntime on the external field as observed in experiments. In the non-homogeneous\ncase, our model account for the two observed maxima of the dielectric loss\ngiving a good quantitative description of experimental data at all frequencies,\nespecially for systems with low molecular mass."
    },
    {
        "anchor": "Distinguishing dynamical features of water inside protein hydration\n  layer: Distribution reveals what is hidden behind the average: Since the pioneering works of Pethig, Grant and Wuthrich on protein hydration\nlayer, many studies have been devoted to find out if there are any general and\nuniversal characteristic features that can distinguish water molecules inside\nthe protein hydration layer from bulk. Given that the surface itself varies\nfrom protein to protein, and that each surface facing the water is\nheterogeneous, search for universal features has been elusive. Here, we perform\natomistic molecular dynamics simulation in order to propose and demonstrate\nthat such defining characteristics can emerge if we look not at average\nproperties but the distribution of relaxation times. We present results of\ncalculations of distributions of residence times and rotational relaxation\ntimes for four different protein-water systems, and compare them with the same\nquantities in the bulk. The distributions in the hydration layer is unusually\nbroad and log-normal in nature, due to the simultaneous presence of peptide\nbackbones that form weak hydrogen bonds, hydrophobic amino acid side chains\nthat form no hydrogen bond and charged polar groups that form strong hydrogen\nbond with the surrounding water molecules. The broad distribution is\nresponsible for the non-exponential dielectric response and also agrees with\nlarge specific heat of the hydration water. Our calculations reveal that while\nthe average time constant is just about 2-3 times larger than that of bulk\nwater, it provides a poor representation of the real behaviour. In particular,\nthe average leads to the erroneous conclusion that water in the hydration layer\nis bulk-like. However, the observed and calculated lower value of static\ndielectric constant of hydration layer remained difficult to reconcile with the\nbroad distribution observed in dynamical properties. We offer a plausible\nexplanation of these unique properties.",
        "positive": "Phantom chain simulations for the effect of stoichiometry on the\n  fracture of star-polymer networks: By phantom chain simulations, it has been recently discovered that the\nfracture characteristics of star polymer networks with different node\nfunctionality and conversion ratios can be described by the cycle rank of the\nnetworks [Masubuchi et al., Macromolecules, doi: 10.1021/acs.macromol.3c01291].\nHowever, due to the employed simplifications and idealizations of the examined\nmodel networks, the results cannot be cast into realistic systems\nstraightforwardly. For instance, the equimolar reaction was assumed in a\nlimited volume for the binary mixture of star prepolymers. For this issue, the\npresent study investigated the effects of stoichiometry by phantom chain\nsimulations. Examined polymer networks were created from binary mixtures of\nstar prepolymers with various mixing ratios by the end-linking reaction via\nBrownian dynamics simulations. The networks were stretched with energy\nminimization until the break. From the mechanical response, strain and stress\nat break and work for fracture were obtained. These fracture characteristics\nslightly decrease with increasing the contrast of volume fractions of the\nbinary prepolymer blends when the node functionality is small and the\nconversion ratio is large. For the other cases, the stoichiometry does not\nimpact the fracture behavior. The number ratio of broken bonds and the cycle\nrank exhibit similar stoichiometry dependence. Consequently, stoichiometry of\nprepolymer blends does not disturb the previously reported relationships\nbetween the fracture characteristics and the cycle rank."
    },
    {
        "anchor": "Characteristics of Deterministic and Stochastic Sandpile Models in a\n  Rotational Sandpile Model: Rotational constraint representing a local external bias generally has\nnon-trivial effect on the critical behavior of lattice statistical models in\nequilibrium critical phenomena. In order to study the effect of rotational bias\nin a out of equilibrium situation like self-organized criticality, a new two\nstate ``quasi-deterministic'' rotational sandpile model is developed here\nimposing rotational constraint on the flow of sand grains. An extended set of\nnew critical exponents are found to characterize the avalanche properties at\nthe non-equilibrium steady state of the model. The probability distribution\nfunctions are found to obey usual finite size scaling supported by negative\ntime autocorrelation between the toppling waves. The model exhibits\ncharacteristics of both deterministic and stochastic sandpile models.",
        "positive": "Microscopic dissipation in a cohesionless granular jet impact: Sufficiently fine granular systems appear to exhibit continuum properties,\nthough the precise continuum limit obtained can be vastly different depending\non the particular system. We investigate the continuum limit of an unconfined,\ndense granular flow. To do this we use as a test system a two-dimensional dense\ncohesionless granular jet impinging upon a target. We simulate this via a\ntimestep driven hard sphere method, and apply a mean-field theoretical approach\nto connect the macroscopic flow with the microscopic material parameters of the\ngrains. We observe that the flow separates into a cone with an interior cone\nangle determined by the conservation of momentum and the dissipation of energy.\nFrom the cone angle we extract a dimensionless quantity $A-B$ that\ncharacterizes the flow. We find that this quantity depends both on whether or\nnot a deadzone --- a stationary region near the target --- is present, and on\nthe value of the coefficient of dynamic friction. We present a theory for the\nscaling of $A-B$ with the coefficient of friction that suggests that\ndissipation is primarily a perturbative effect in this flow, rather than the\nsource of qualitatively different behavior."
    },
    {
        "anchor": "Monte Carlo Simulation of Smectic Liquid Crystals and the Electroclinic\n  Effect: the Role of the Molecular Shape: Using Monte Carlo simulation methods, we explore the role of molecular shape\nin the phase behavior of liquid crystals and the electroclinic effect. We study\na \"bent-rod\" mesogen shaped like the letter Z, composed of seven soft spheres\nbonded rigidly together with no intra-molecular degrees of freedom. For\nstrongly angled molecules, we find that steric repulsion alone provides the\ndriving force for a smectic-C phase, even without intermolecular dipole-dipole\ninteractions. For weakly angled (nearly rod-like) molecules, we find a stable\nsmectic-A (SmA) phase and a strong electroclinic effect with a saturation tilt\nangle of about 19 degrees. In the SmA phase we find evidence of vortex-like\npoint defects. We also observe a field-induced nematic-smectic phase\ntransition.",
        "positive": "Spatial Organization of Active Particles with Field Mediated\n  Interactions: We consider a system of independent point-like particles performing a\nBrownian motion while interacting with a Gaussian fluctuating background. These\nparticles are in addition endowed with a discrete two-state internal degree of\nfreedom that is subjected to a nonequilibrium source of noise, which affects\ntheir coupling with the background field. We explore the phase diagram of the\nsystem and pinpoint the role of the nonequilibrium drive in producing a\nnontrivial patterned spatial organization. We are able, by means of a weakly\nnonlinear analysis, to account for the parameter-dependence of the boundaries\nof the phase and pattern diagram in the stationary state."
    },
    {
        "anchor": "Ikeda and Miyazaki Reply to Rolf Schilling and Bernhard Schmid\n  [arXiv:1101.5577]: Reply to the preceding comment by Rolf Schilling and Bernhard Schmid\n[arXiv:1101.5577, Phys. Rev. Lett. 106, 049601 (2011)].",
        "positive": "The Electrochemical Surface Potential Due to Classical Point Charge\n  Models Drives Anion Adsorption to the Air-Water Interface: We demonstrate that the driving forces for ion adsorption to the air-water\ninterface for point charge models results from both cavitation and a term that\nis of the form of a negative electrochemical surface potential. We carefully\ncharacterize the role of the free energy due to the electrochemical surface\npotential computed from simple empirical models and its role in ionic\nadsorption within the context of dielectric continuum theory. Our research\nsuggests that the electrochemical surface potential due to point charge models\nprovides anions with a significant driving force to the air-water interface.\nThis is contrary to the results of ab initio simulations that indicate that the\naverage electrostatic surface potential should favor the desorption of anions\nat the air-water interface. The results have profound implications for the\nstudies of ionic distributions in the vicinity of hydrophobic surfaces and\nproteins."
    },
    {
        "anchor": "Velocity dependence of friction of confined polymers: We present molecular dynamics friction calculations for confined hydrocarbon\nsolids with molecular lengths from 20 to 1400 carbon atoms. Two cases are\nconsidered: (a) polymer sliding against a hard substrate, and (b) polymer\nsliding on polymer. We discuss the velocity dependence of the frictional shear\nstress for both cases. In our simulations, the polymer films are very thin\n(approx. 3 nm), and the solid walls are connected to a thermostat at a short\ndistance from the polymer slab. Under these circumstances we find that\nfrictional heating effects are not important, and the effective temperature in\nthe polymer film is always close to the thermostat temperature. In the first\nsetup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon\natoms, the shear stresses are nearly independent of molecular length, but for\nthe shortest hydrocarbon C20H42 the frictional shear stress is lower. In all\ncases the frictional shear stress increases monotonically with the sliding\nvelocity. For polymer sliding on polymer [case (b)] the friction is much\nlarger, and the velocity dependence is more complex. For hydrocarbons with\nmolecular lengths from 60 to 140 C-atoms, the number of monolayers of lubricant\nincreases (abruptly) with increasing sliding velocity (from 6 to 7 layers),\nleading to a decrease of the friction. Before and after the layering\ntransition, the frictional shear stresses are nearly proportional to the\nlogarithm of sliding velocity. For the longest hydrocarbon (1400 C-atoms) the\nfriction shows no dependence on the sliding velocity, and for the shortest\nhydrocarbon (20 C-atoms) the frictional shear stress increases nearly linearly\nwith the sliding velocity.",
        "positive": "Jamming on curved surfaces: Colloidal and other granular media experience a transition to rigidity known\nas jamming if the fill fraction is increased beyond a critical value. The\nresulting jammed structures are locally disordered, bear applied loads\ninhomogenously, possess the minimal number of contacts required for stability\nand elastic properties that scale differently with volume fraction to\ncrystalline media. Here the jamming transition is studied on a curved\nellipsoidal surface by computer simulation, where shape evolution leads to a\nreduction in area, crowding the particles and preventing further evolution of\nthe surface. The arrested structures can be unjammed and the surface further\nevolved iteratively, eventually leading to a rigid metric-jammed state that is\nstable with respect to motion of the particles and some specified space of\ndeformations of the manifold. The structures obtained are compared with those\nobtained in flat space; it is found that jammed states in curved geometries\nrequire fewer contacts per particle due to the nonlinearity of the surface\nconstraints. In addition, structures composed of soft particles are compressed\nabove the jamming point. It is observed that relatively well-ordered but\ngeometrically frustrated monodisperse packings share many signatures of\ndisordered bidisperse packings."
    },
    {
        "anchor": "Viscoelastic shear banding in foam: Shear banding is an important feature of flow in complex fluids. Essentially,\nshear bands refer to the coexistence of flowing and non-flowing regions in\ndriven material. Understanding the possible sources of shear banding has\nimportant implications for a wide range of flow applications. In this regard,\nquasi-two dimensional flow offers a unique opportunity to study competing\nfactors that result in shear bands. One proposal is the competition between\nintrinsic dissipation and an external source of dissipation. In this paper, we\nreport on the experimental observation of the transition between different\nclasses of shear-bands that have been predicted to exist in cylindrical\ngeometry as the result of this competition [R. J. Clancy, E. Janiaud, D.\nWeaire, and S. Hutzlet, Eur. J. Phys. E, {\\bf 21}, 123 (2006)].",
        "positive": "Fragmentation of brittle plates by localized impact: In this letter we address the fragmentation of thin, brittle layers due to\nthe impact of high-velocity projectiles. Our approach is a geometric\nstatistical one, with lines and circles playing the role of cracks, randomly\ndistributed over the surface. The specific probabilities employed to place the\nfractures come from an analysis of how the energy input propagates and\ndissipates over the material. The cumulative mass distributions $F(m)$ we\nobtain are in excellent agreement with the experimental data produced by T.\nKadono [Phys. Rev. Lett. {\\bf 78}, 1444 (1997)]. Particularly, in the small\nmass regime we get $F(m)\\sim m^{-\\alpha}$, with $0.1<\\alpha<0.3$ for a quite\nbroad range of dissipation strengths and total number of fragments. In addition\nwe obtain the fractal dimension of the set of cracks and its correlation to the\nexponent $\\alpha$ that account for the experimental results given by Kadono and\nArakawa [Phys. Rev. E {\\bf 65}, 035107(R) (2002)]."
    },
    {
        "anchor": "Dynamics in the Metabasin Space of a Lennard-Jones Glass Former:\n  Connectivity and Transition Rates: Using simulations, we construct the effective dynamics in metabasin space for\na Lennard-Jones glass-former. Metabasins are identified via a scheme that\nmeasures transition rates between inherent structures, and generates clusters\nof inherent structures by drawing in branches that have the largest transition\nrates. The effective dynamics is shown to be Markovian but differs\nsignificantly from the simplest trap models. We specifically show that\nretaining information about the connectivity in metabasin space is crucial for\nreproducing the slow dynamics observed in this system.",
        "positive": "Revolving rivers in sandpiles: from continuous to intermittent flows: In a previous paper [Phys. Rev. Lett. 91, 014501 (2003)], the mechanism of\n\"revolving rivers\" for sandpile formation is reported: as a steady stream of\ndry sand is poured onto a horizontal surface, a pile forms which has a river of\nsand on one side owing from the apex of the pile to the edge of the base. For\nsmall piles the river is steady, or continuous. For larger piles, it becomes\nintermittent. In this paper we establish experimentally the \"dynamical phase\ndiagram\" of the continuous and intermittent regimes, and give further details\nof the piles topography, improving the previous kinematic model to describe it\nand shedding further light on the mechanisms of river formation. Based on\nexperiments in Hele-Shaw cells, we also propose that a simple dimensionality\nreduction argument can explain the transition between the continuous and\nintermittent dynamics."
    },
    {
        "anchor": "Phase Diagram for Unzipping DNA Using a Bond-Force Criterion: Using the criterion that the mechanical unzipping transition in a bound\nhomopolymer is triggered when the average force exerted by the single unbound\nstrands on the first base pair in the bound section exceeds the force binding\nthe pair together, the temperature dependence of the critical unzipping force\nis obtained. In the resulting phase diagram, the critical force decreases\nmonotonically with increasing temperature, from a finite value at zero Kelvin\nto zero at the critical temperature.",
        "positive": "Passive defect driven morphogenesis in nematic membranes: Topological defects are ubiquitous on surfaces with orientational order\nfields. Here, we study equilibrium states generated by the feedback between\ngeometry and nematic order on fluid membranes with an integer topological\ndefect. When the Frank elastic constants associated with the orientational\nfield dominate, the surfaces spontaneously deform toward an conical shape\nfeaturing an aster topological defect at its apex. In the case of vanishing\ntension this is a solution to the normal force balance. We show that the\nstability of the surface depends on the balance of the elastic parameters and\nthe phase of the defect. When boundary constraints are introduced, we observe\nthree distinct modes of deformation. These deformation modes take advantage of\nthe way in which splay, twist and bend distortions of the director field can be\nexchanged on a curved surface. We discuss how these deformation modes are\ndistinguished by their response to the cost of twist distortions and the\nexistence of inverted solutions. Our findings show that fusion of +1/2\ntopological defect pairs can reduce the total energy of deformable surfaces.\nFinally, we argue how these results can be relevant for biological systems."
    },
    {
        "anchor": "State-dependent diffusion: thermodynamic consistency and its path\n  integral formulation: The friction coefficient of a particle can depend on its position as it does\nwhen the particle is near a wall. We formulate the dynamics of particles with\nsuch state-dependent friction coefficients in terms of a general Langevin\nequation with multiplicative noise, whose evaluation requires the introduction\nof specific rules. Two common conventions, the Ito and the Stratonovich,\nprovide alternative rules for evaluation of the noise, but other conventions\nare possible. We show the requirement that a particle's distribution function\napproach the Boltzmann distribution at long times dictates that a drift term\nmust be added to the Langevin equation. This drift term is proportional to the\nderivative of the diffusion coefficient times a factor that depends on the\nconvention used to define the multiplicative noise. We explore the consequences\nof this result in a number examples with spatially varying diffusion\ncoefficients. We also derive path integral representations for arbitrary\ninterpretation of the noise, and use it in a perturbative study of correlations\nin a simple system.",
        "positive": "Dissipative Dynamics of a Josephson Junction In the Bose-Gases: The dissipative dynamics of a Josephson junction in the Bose-gases is\nconsidered within the framework of the model of a tunneling Hamiltonian. The\neffective action which describes the dynamics of the phase difference across\nthe junction is derived using functional integration method. The dynamic\nequation obtained for the phase difference across the junction is analyzed for\nthe finite temperatures in the low frequency limit involving the radiation\nterms. The asymmetric case of the Bose-gases with the different order\nparameters is calculated as well."
    },
    {
        "anchor": "A Monte Carlo Study of Equilibrium Polymers in a Shear Flow: We use an off-lattice microscopic model for solutions of equilibrium polymers\n(EP) in a lamellar shear flow generated by means of a self-consistent external\nfield between parallel hard walls.\n  The individual conformations of the chains are found to elongate in flow\ndirection and shrink perpendicular to it while the average polymer length\ndecreases with increasing shear rate.\n  The Molecular Weight Distribution of the chain lengths retains largely its\nexponential form in dense solutions whereas in dilute solutions it changes from\na power-exponential Schwartz distribution to a purely exponential one upon an\nincrease of the shear rate.",
        "positive": "Formation of aeolian ripples and sand sorting: We present a continuous model capable of demonstrating some salient features\nof aeolian sand ripples: the realistic asymmetric ripple shape, coarsening of\nripple field at the nonlinear stage of ripple growth, saturation of ripple\ngrowth for homogeneous sand, typical size segregation of sand and formation of\narmoring layers of coarse particles on ripple crests and windward slopes if\nsand is inhomogeneous."
    },
    {
        "anchor": "Theory of adhesion: role of surface roughness: We discuss how surface roughness influence the adhesion between elastic\nsolids. We introduce a Tabor number which depends on the length scale or\nmagnification, and which gives information about the nature of the adhesion at\ndifferent length scales. We consider two limiting cases relevant for (a)\nelastically hard solids with weak adhesive interaction (DMT-limit) and (b)\nelastically soft solids or strong adhesive interaction (JKR-limit). For the\nformer cases we study the nature of the adhesion using different adhesive force\nlaws ($F\\sim u^{-n}$, $n=1.5-4$, where $u$ is the wall-wall separation). In\ngeneral, adhesion may switch from DMT-like at short length scales to JKR-like\nat large (macroscopic) length scale. We compare the theory predictions to the\nresults of exact numerical simulations and find good agreement between theory\nand the simulation results.",
        "positive": "Distinct viscoelastic scaling for isostatic spring networks of the same\n  fractal dimension: Fractal structure emerges spontaneously from the chemical cross\\-linking of\nmonomers into hydrogels, and has been directly linked to power law\nvisco\\-elasticity at the gel transition, as recently demonstrated for isostatic\n(marginally--rigid) spring networks based on the Sierpinski triangle. Here we\ngeneralize the Sierpinski triangle generation rules to produce 4 fractals, all\nwith the same dimension $d_{\\rm f}=\\log 3/\\log 2$, with the Sierpinski triangle\nbeing one case. We show that spring networks derived from these fractals are\nall isostatic, but exhibit one of two distinct exponents for their power--law\nviscoelasticity. We conclude that, even for networks with fixed connectivity,\npower--law viscoelasticity cannot generally be a function of the fractal\ndimension alone."
    },
    {
        "anchor": "Mode-coupling theory for multiple decay channels: We investigate the properties of a class of mode-coupling equations for the\nglass transition where the density mode decays into multiple relaxation\nchannels. We prove the existence and uniqueness of the solutions for Newtonian\nas well as Brownian dynamics and demonstrate that they fulfill the requirements\nof correlation functions, in the latter case the solutions are purely\nrelaxational. Furthermore, we construct an effective mode-coupling functional\nwhich allows to map the theory to the case of a single decay channel, such that\nthe covariance principle found for the mode-coupling theory for simple liquids\nis properly generalized. This in turn allows establishing the maximum theorem\nstating that long-time limits of mode-coupling solutions can be calculated as\nmaximal solutions of a fixed-point equation without relying on the dynamic\nsolutions.",
        "positive": "O'Connor, Alvarez, and Robbins Reply to Xu et al. (arXiv:1808.05390): The preceding Comment by Xu et al. (Phys. Rev. Lett. 122, 059803 (2019);\narXiv:1808.05390) erroneously applies the entropic stress expression in our\nLetter (T.C. O'Connor et al., Phys. Rev. Lett. 121, 047801 (2018);\narXiv:1806.09509) to transient stress. In addition, the authors only apply this\nexpression at extreme extension rates where we clearly showed deviations from\nthe entropic stress expression for steady-state extensional flow. Hence the\nsurprisingly minor discrepancies noted in the Comment between observed and\n\"predicted\" stress are entirely expected and have no bearing on the discussion\nor conclusions in our Letter."
    },
    {
        "anchor": "X-ray tomography investigation of cyclically sheared granular materials: We perform combined X-ray tomography and shear force measurements on a\ncyclically sheared granular system with highly transient behaviors, and obtain\nthe evolution of microscopic structures and the macroscopic shear force during\nthe shear cycle. We explain the macroscopic behaviors of the system based on\nmicroscopic processes, including the particle level structural rearrangement\nand frictional contact variation. Specifically, we show how contact friction\ncan induce large structural fluctuations and cause significant shear dilatancy\neffect for granular materials, and we also construct an empirical constitutive\nrelationship for the macroscopic shear force.",
        "positive": "Twist-bend nematic phases of bent-shaped biaxial molecules: How change in molecular structure can affect relative stability and\nstructural properties of the twist-bend nematic phase (N$_\\text{TB}$)? Here we\nextend the mean-field model [C. Greco et al., Soft Matter, 2014, 10, 9318] for\nbent-shaped achiral molecules, to study the influence of arm molecular\nbiaxiality and the value of molecule's bend angle on relative stability of\nN$_\\text{TB}$. In particular we show that by controlling biaxiality of\nmolecule's arms up to four ordered phases can become stable. They involve\nlocally uniaxial and biaxial variants of N$_\\text{TB}$, together with the\nuniaxial and the biaxial nematic phases. However, the V-shaped molecule show\nstronger ability to form stable N$_\\text{TB}$ than a biaxial nematic phase,\nwhere the latter phase appears in the phase diagram only for bend angles\ngreater than $140^\\circ$ and for large biaxiality of the two arms."
    },
    {
        "anchor": "Tuning the size and configuration of nanocarbon microcapsules: aqueous\n  method using optical tweezers: To date, optical manipulation techniques for aqueous dispersions have been\ndeveloped that deposit and/or transport nanoparticles not only for fundamental\nstudies of colloidal dynamics, but also for either creating photonic devices or\nallowing accurate control of liquids on micron scales. Here, we report that\noptical tweezers (OT) system is able to direct three-dimensional assembly of\ngraphene, graphite, and carbon nanotubes (CNT) into microcapsules of hollow\nspheres. The OT technique facilitates both to visualize the elasticity of a CNT\nmicrocapsule and to arrange a triplet of identical graphene microcapsules in\naqueous media. Furthermore, the similarity of swelling courses has been found\nover a range of experimental parameters such as nanocarbon species, the power\nof the incident light, and the suspension density. Thanks to the universality\nin evolutions of rescaled capsule size, we can precisely control the size of\nvarious nanocarbon microcapsules by adjusting the duration time of laser\nemission.",
        "positive": "Structure and dynamics of ring polymers: entanglement effects because of\n  solution density and ring topology: The effects of entanglement in solutions and melts of unknotted ring polymers\nhave been addressed by several theoretical and numerical studies. The system\nproperties have been typically profiled as a function of ring contour length at\nfixed solution density. Here, we use a different approach to investigate\nnumerically the equilibrium and kinetic properties of solutions of model ring\npolymers. Specifically, the ring contour length is maintained fixed, while the\ninterplay of inter- and intra-chain entanglement is modulated by varying both\nsolution density (from infinite dilution up to \\approx 40 % volume occupancy)\nand ring topology (by considering unknotted and trefoil-knotted chains). The\nequilibrium metric properties of rings with either topology are found to be\nonly weakly affected by the increase of solution density. Even at the highest\ndensity, the average ring size, shape anisotropy and length of the knotted\nregion differ at most by 40% from those of isolated rings. Conversely, kinetics\nare strongly affected by the degree of inter-chain entanglement: for both\nunknots and trefoils the characteristic times of ring size relaxation,\nreorientation and diffusion change by one order of magnitude across the\nconsidered range of concentrations. Yet, significant topology-dependent\ndifferences in kinetics are observed only for very dilute solutions (much below\nthe ring overlap threshold). For knotted rings, the slowest kinetic process is\nfound to correspond to the diffusion of the knotted region along the ring\nbackbone."
    },
    {
        "anchor": "Temperature dependence of fast relaxation processes in amorphous\n  materials: We examine the structural relaxation of glassy materials at finite\ntemperatures, considering the effect of activated rearrangements and long-range\nelastic interactions. Our three-dimensional mesoscopic relaxation model shows\nhow the displacements induced by localized relaxation events can result in\nfaster-than-exponential relaxation. Thermal activation allows for local\nrearrangements, which generate elastic responses and possibly cascades of new\nrelaxation events. To study the interplay between this elastically-dominated\nand thermally-dominated dynamics, we introduce tracer particles that follow the\ndisplacement field induced by the local relaxation events and also incorporate\nBrownian motion. Our results reveal that the dynamic exponents and shape\nparameter of the dynamical structure factor depend on this competition and\ndisplay a crossover from faster-than-exponential to exponential relaxation as\ntemperature increases, consistent with recent observations in metallic glasses.\nAdditionally, we find the distribution of waiting times between activations to\nbe broadly distributed at low temperatures, providing a measure of dynamical\nheterogeneities characteristic for to glassy dynamics.",
        "positive": "Amplification of Fluctuations in Unstable Systems with Disorder: We study the early-stage kinetics of thermodynamically unstable systems with\nquenched disorder. We show analytically that the growth of initial fluctuations\nis amplified by the presence of disorder. This is confirmed by numerical\nsimulations of morphological phase separation (MPS) in thin liquid films and\nspinodal decomposition (SD) in binary mixtures. We also discuss the\nexperimental implications of our results."
    },
    {
        "anchor": "Contact nonlinearities and linear response in jammed particulate\n  packings: Packings of frictionless athermal particles that interact only when they\noverlap experience a jamming transition as a function of packing density. Such\npackings provide the foundation for the theory of jamming. This theory rests on\nthe observation that, despite the multitude of disordered configurations, the\nmechanical response to linear order depends only on the distance to the\ntransition. We investigate the validity and utility of such measurements that\ninvoke the harmonic approximation and show that, despite particles coming in\nand out of contact, there is a well-defined linear regime in the thermodynamic\nlimit.",
        "positive": "Magnetically Responsive PDMS with aligned nickel coated carbon fibres: We detail a technique to produce actuators able to bear large strain and\nrespond to an external magnetic field. The material used is PDMS reinforced\nwith nickel coated carbon fibres. Thanks to the nickel functionalisation, the\nfibre orientation can be achieved by embedding the viscous solution into a low\nexternal magnetic field ($<0.2$~T). It is shown that both mechanical and\nmagnetic properties can be controlled by tailoring the material anisotropy\nthrough properly orientating the reinforcing fibres in the pre-curing phase.\nThe large strain behaviour is investigated by tensile testing up to 60 % of\ndeformation and shows a strong dependence on the fibre orientation. The\nmagnetic properties are investigated by placing beam-like specimens into a\nuniform magnetic field. The results show a multistable behaviour with a\ntransition from a bending-only deformed configuration for the 0$^\\circ$ fibres\nspecimen, to a twisting only configuration, achieved for fibres at 90$^\\circ$\nwhereas all the intermediate angles show both bending and twisting. This\nbehaviour is accurately captured by the large rotations beam model introduced.\nSuch an actuator can be used in all applications which require fast response\ntimes and large strain."
    },
    {
        "anchor": "Evidence of a first-order smectic -- hexatic transition and its\n  proximity to tricritical point in smectic films: Experimental and theoretical studies of a smectic-hexatic transition in\nfreely suspended films of 54COOBC compound are presented. X-ray investigations\nrevealed a discontinuous first-order transition into the hexatic phase.\nMoreover, the temperature region of two phase coexistence near the phase\ntransition point diminishes with film thickness. The coexistence width\ndependence on film thickness was derived on the basis of the Landau mean-field\ntheory in the vicinity of the tricritical point (TCP). Close to TCP the surface\nhexatic ordering penetrates anomalously deep into the film interior.",
        "positive": "Learning hydrodynamic equations for active matter from particle\n  simulations and experiments: Recent advances in high-resolution imaging techniques and particle-based\nsimulation methods have enabled the precise microscopic characterization of\ncollective dynamics in various biological and engineered active matter systems.\nIn parallel, data-driven algorithms for learning interpretable continuum models\nhave shown promising potential for the recovery of underlying partial\ndifferential equations (PDEs) from continuum simulation data. By contrast,\nlearning macroscopic hydrodynamic equations for active matter directly from\nexperiments or particle simulations remains a major challenge. Here, we present\na framework that leverages spectral basis representations and sparse regression\nalgorithms to discover PDE models from microscopic simulation and experimental\ndata, while incorporating the relevant physical symmetries. We illustrate the\npractical potential through applications to a chiral active particle model\nmimicking swimming cells and to recent microroller experiments. In both cases,\nour scheme learns hydrodynamic equations that reproduce quantitatively the\nself-organized collective dynamics observed in the simulations and experiments.\nThis inference framework makes it possible to measure a large number of\nhydrodynamic parameters in parallel and directly from video data."
    },
    {
        "anchor": "Drop Impact Dynamics of Complex Fluids: A Review: The impact of fluid drops on solid substrates has widespread interest in many\nindustrial coating and spraying applications, such as ink-jet printing and\nagricultural pesticide sprays. Many of the fluids used in these applications\nare non-Newtonian, that is they contain particulate or polymeric additives\nwhich strongly modify their flow behaviour. While a large body of experimental\nand theoretical work has been done to understand the impact dynamics of\nNewtonian fluids, we as a community have much progress to make to understand\nhow these dynamics are modified when the impact fluid has a non-Newtonian\nrheology. In this review, we outline recent experimental, theoretical, and\ncomputational advances in the study of impact dynamics of complex fluids on\nsolid surfaces. Here, we provide an overview of this field that is geared\ntowards a multidisciplinary audience. Our discussion is segmented by two\nprincipal material constitutions: polymeric fluids and particulate suspensions.\nThroughout, we highlight promising future directions, as well as ongoing\nexperimental and theoretical challenges in the field.",
        "positive": "Identification of long-lived clusters and their link to slow dynamics in\n  a model glass former: We study the relationship between local structural ordering and dynamical\nheterogeneities in a model glass-forming liquid, the Wahnstrom mixture. A novel\ncluster-based approach is used to detect local energy minimum polyhedral\nclusters and local crystalline environments. A structure-specific time\ncorrelation function is then devised to determine their temporal stability. For\nour system, the lifetime correlation function for icosahedral clusters decays\nfar slower than for those of similarly sized but topologically distinct\nclusters. Upon cooling, the icosahedra form domains of increasing size and\ntheir lifetime increases with the size of the domains. Furthermore, these\nlong-lived domains lower the mobility of neighboring particles. These\nstructured domains show correlations with the slow regions of the dynamical\nheterogeneities that form on cooling towards the glass transition. Although\nicosahedral clusters with a particular composition and arrangement of large and\nsmall particles are structural elements of the crystal, we find that most\nicosahedral clusters lack such order in composition and arrangement and thus\nlocal crystalline ordering makes only a limited contribution to this process.\nFinally, we characterize the spatial correlation of the domains of icosahedra\nby two structural correlation lengths and compare them with the four-point\ndynamic correlation length. All the length scales increase upon cooling, but in\ndifferent ways."
    },
    {
        "anchor": "Simulation of a flat folding nano-swimmer confined in a nanopore: We use molecular dynamics simulations to investigate the displacement of a\nsimple butterfly-like molecular motor inside nanopores of various radii filled\nwith a viscous medium. The medium is modeled with a versatile potential that\nmay be adjusted to represent a large number of materials. It was found\npreviously that the motor folding not only increases its displacement but also\ncreates elementary diffusion processes inside the medium, related to the\nopening angle of the motor folding. The presence of these processes changes the\nmedium dynamics and in turn affects the motor displacement. Therefore we test\nthe motor displacement with different activations of the medium inside the pore\nby varying the motor opening angles. We find that the optima of the motor\ndisplacement oscillate with pore sizes and that the optimal radii depend on the\nactivation of the medium. These results imply that it is possible to choose the\nactivation or opening angle that optimizes the motor displacement for a given\npore size. Results also show that the activation decreases strongly the\nconfinement hindering of the motor motion, in particular for small pores.\nFinally, analyzing the distribution probability of the motor position and the\ndensity of elementary motions we find that the motor is mainly located in the\ncenter of the pore. We find spikes in the density of elementary motions when\nthe motor goes away from the center, suggesting important contributions of the\nmotor bouncing motions on the pore walls.",
        "positive": "Entropically driven transition to a liquid-crystalline polymer globule: A self-consistent-field theory (SCFT) in the grand canonical ensemble\nformulation is used to study transitions in a helix-coil multiblock copolymer\nglobule. The helices are modeled as stiff rods. In addition to the established\ncoil-globule transition we show for the first time that, even without explicit\nrod-rod alignment interaction, the system undergoes a transition to a nematic\nliquid-crystalline (LC) globular state. The LC-globule formation is driven by\nthe hydrophobic helical segment attraction and the anisotropy of the globule\nsurface energy. The full phase diagram of the copolymer was calculated. It\ndiscriminates between an open chain, amorphous globule and LC-globule. This\nmodel provides a relatively simple example of the interplay between secondary\nand tertiary structures in homopolypeptides. Moreover, it gives a simple\nexplanation for the formation of helix bundles in certain globular proteins."
    },
    {
        "anchor": "Dual Chain Perturbation theory: A new equation of state for polyatomic\n  molecules: In the development of equations of state for polyatomic molecules,\nthermodynamic perturbation theory (TPT) is widely used to calculate the change\nin free energy due to chain formation. TPT is a simplification of a more\ngeneral and exact multi-density cluster expansion for associating fluids. In\nTPT all contributions to the cluster expansion which contain chain - chain\ninteractions are neglected. That is, all inter-chain interactions are treated\nat the reference fluid level. This allows for the summation of the cluster\ntheory in terms of reference system correlation functions only. While highly\nsuccessful, TPT has many handicaps which result from the neglect of chain -\nchain interactions. The subject of this document is to move beyond the\nlimitations of TPT, and included chain - chain contributions to the equation of\nstate.",
        "positive": "Hydrodynamic Mobility Reversal of Squirmers near Flat and Curved\n  Surfaces: Self-propelled particles have been experimentally shown to orbit spherical\nobstacles and move along surfaces. Here, we theoretically and numerically\ninvestigate this behavior for a hydrodynamic squirmer interacting with\nspherical objects and flat walls using three different methods of approximately\nsolving the Stokes equations: The method of reflections, which is accurate in\nthe far field; lubrication theory, which describes the close-to-contact\nbehavior; and a lattice Boltzmann solver that accurately accounts for\nnear-field flows. The method of reflections predicts three distinct behaviors:\norbiting/sliding, scattering, and hovering, with orbiting being favored for\nlower curvature as in the literature. Surprisingly, it also shows backward\norbiting/sliding for sufficiently strong pushers, caused by fluid recirculation\nin the gap between the squirmer and the obstacle leading to strong forces\nopposing forward motion. Lubrication theory instead suggests that only hovering\nis a stable point for the dynamics. We therefore employ lattice Boltzmann to\nresolve this discrepancy and we qualitatively reproduce the richer far-field\npredictions. Our results thus provide insight into a possible mechanism of\nmobility reversal mediated solely through hydrodynamic interactions with a\nsurface."
    },
    {
        "anchor": "Acoustic monitoring of the gelation of a colloidal suspension: Because they are sensitive to mechanical properties of materials and can\npropagate even in opaque systems, acoustic waves provides us with a powerful\ncharacterization tool in numerous fields. Common techniques mostly rely on\ntime-of-flight measurements and do not exploit the spectral content: however,\nsound speed and attenuation spectra contain rich information. Such an acoustic\nspectroscopy already exists and allows to retrieve subtle information on\nsystems of well-known physico-chemistry, but modeling becomes out of reach for\nindustrial systems. In this article, we use a simple empirical approach to\nmonitor the gelation of silica suspensions: we show that the gelation time\nobtained from acoustic measurements is proportional to this determined with\nmore conventional rheological characterization. Such a results thus opens the\nway for in-situ monitoring of time-evolving systems in industrial context with\nacoustic methods only.",
        "positive": "Clustering of entanglement points in highly strained polymer melts: Polymer melts undergoing large deformation by uniaxial elongation are studied\nby molecular dynamics simulations of bead-spring chains in melts. Applying a\nprimitive path analysis to strongly deformed polymer melts, the role of\ntopological constrains in highly entangled polymer melts is investigated and\nquantified. We show that the over-all, large scale conformations of the\nprimitive paths (PPs) of stretched chains follow affine deformation while the\nnumber and the distribution of entanglement points along the PPs do not. Right\nafter deformation, PPs of chains retract in both directions parallel and\nperpendicular to the elongation. Upon further relaxation we observe a\nlong-lived clustering of entanglement points. Together with the delayed\nrelaxation time this leads to a metastable inhomogeneous distribution of\ntopological constraints in the melts."
    },
    {
        "anchor": "On modifying properties of polymeric melts by nanoscopic particles: We study geometric and energetic factors that partake in modifying properties\nof polymeric melts via inserting well-dispersed nanoscopic particles (NP).\nModel systems are polybutadiene melts including 10-150 atom atomic clusters\n(0.1-1.5% v/v). We tune interactions between chains and particle by van der\nWaals terms. Using molecular dynamics we study equilibrium fluctuations and\ndynamical properties at the interface. Effect of bead size and interaction\nstrength both on volume and volumetric fluctuations is manifested in mechanical\nproperties, quantified here by bulk modulus, K. Tuning NP size and non-bonded\ninteractions results in ~15% enhancement in K by addition of a maximum of 1.5%\nv/v NP.",
        "positive": "Density-dependent interactions and structure of charged colloidal\n  dispersions in the weak screening regime: We determine the structure of charge-stabilized colloidal suspensions at low\nionic strength over an extended range of particle volume fractions using a\ncombination of light and small angle neutron scattering experiments. The\nvariation of the structure factor with concentration is analyzed within a\none-component model of a colloidal suspension. We show that the observed\nstructural behavior corresponds to a non-monotonic density dependence of the\ncolloid effective charge and the mean interparticle interaction energy. Our\nfindings are corroborated by similar observations from primitive model computer\nsimulations of salt-free colloidal suspensions."
    },
    {
        "anchor": "Power-law velocity distributions in granular gases: We report a general class of steady and transient states of granular gases.\nWe find that the kinetic theory of inelastic gases admits stationary solutions\nwith a power-law velocity distribution, f(v) ~ v^(-sigma). The exponent sigma\nis found analytically and depends on the spatial dimension, the degree of\ninelasticity, and the homogeneity degree of the collision rate. Driven\nsteady-states, with the same power-law tail and a cut-off can be maintained by\ninjecting energy at a large velocity scale, which then cascades to smaller\nvelocities where it is dissipated. Associated with these steady-states are\nfreely cooling time-dependent states for which the cut-off decreases and the\nvelocity distribution is self-similar.",
        "positive": "Start-up inertia as an origin for heterogeneous flow: For quite some time non-monotonic flow curve was thought to be a requirement\nfor shear banded flows in complex fluids. Thus, in simple yield stress fluids\nshear banding was considered to be absent. Recent spatially resolved\nrheological experiments have found simple yield stress fluids to exhibit shear\nbanded flow profiles. One proposed mechanism for the initiation of such\ntransient shear banding process has been a small stress heterogeneity rising\nfrom the experimental device geometry. Here, using Computational Fluid Dynamics\nmethods, we show that transient shear banding can be initialized even under\nhomogeneous stress conditions by the fluid start-up inertia, and that such\nmechanism indeed is present in realistic experimental conditions."
    },
    {
        "anchor": "Decoherence of Bose-Einstein condensates in microtraps: We discuss the impact of thermally excited near fields on the coherent\nexpansion of a condensate in a miniaturized electromagnetic trap.\n  Monte Carlo simulations are compared with a kinetic two-component theory and\nindicate that atom interactions can slow down decoherence. This is explained by\na simple theory in terms of the condensate dynamic structure factor.",
        "positive": "Unraveling the Molecular Magic: AI Insights on the Formation of\n  Extraordinarily Stretchable Hydrogels: The deliberate manipulation of ammonium persulfate, methylenebisacrylamide,\ndimethyleacrylamide, and polyethylene oxide concentrations resulted in the\ndevelopment of a hydrogel with an exceptional stretchability, capable of\nextending up to 260 times its original length. This study aims to elucidate the\nmolecular architecture underlying this unique phenomenon by exploring potential\nreaction mechanisms, facilitated by an artificial intelligence prediction\nsystem. Artificial intelligence predictor introduces a novel approach to\ninterlinking two polymers, involving the formation of networks interconnected\nwith linear chains following random chain scission. This novel configuration\nleads to the emergence of a distinct type of hydrogel, herein referred to as a\n\"Span Network.\" Additionally, Fourier-transform infrared spectroscopy (FTIR) is\nused to investigate functional groups that may be implicated in the proposed\nmechanism, with ester formation confirmed among numerous hydroxyl end groups\nobtained from chain scission of PEO and carboxyl groups formed on hydrogel\nnetworks."
    },
    {
        "anchor": "Stripes, Clusters, and Nonequilibrium Ordering for Bidisperse Colloids\n  with Repulsive Interactions: We show that two-dimensional bidisperse assemblies of colloids with strictly\nrepulsive interactions exhibit stripe, cluster, and partially crystallized\nstates when driven over a quenched random substrate. The nonequilibrium states\non a substrate are significantly more ordered than equilibrium states both with\nand without substrates. A minimum substrate strength is necessary to induce the\nnonequilibrium pattern formation. Our results suggest that a combination of\ndriving and quenched disorder offers a new approach to controlling pattern\nformation in colloid mixtures.",
        "positive": "A nonlinear dynamical system approach for the yielding behaviour of a\n  viscoplastic fluid: A nonlinear dynamical system model that approximates a microscopic Gibbs\nfield model for the yielding of a viscoplastic material subjected to varying\nexternal stress recently reported in [1] is presented. The predictions of the\nmodel are in a fair agreement with the microscopic simulations and in a very\ngood agreement with the microstructural semi-empirical model reported in [2].\nWith only two internal parameters, the nonlinear dynamical system model\ncaptures several key features of the solid-fluid transition observed in\nexperiments: the effect of the interactions between microscopic constituents on\nthe yield point, the abruptness of solid-fluid transition and the emergence of\na hysteresis of the micro-structural states upon increasing/decreasing external\nforcing.The scaling behaviour of the magnitude of the hysteresis with the\ndegree of the steadiness of the flow is consistent with previous experimental\nobservations."
    },
    {
        "anchor": "Predicting plasticity of amorphous solids from instantaneous normal\n  modes: We present a mathematical description of amorphous solid deformation and\nplasticity by extending the concept of instantaneous normal modes (INMs) to\ndeformed systems, which allows us to retain the effect of strain on the\nvibrational density of states (VDOS). Starting from the nonaffine lattice\ndynamics (NALD) description of elasticity and viscoelasticity of glasses, we\nformulate the linear response theory up to large deformations by considering\nthe strain-dependent tangent modulus at finite values of shear strain. The\n(nonaffine) tangent shear modulus is computed from the vibrational density of\nstates (VDOS) of affinely strained configurations at varying strain values. The\naffine strain, found analytically on the static (undeformed) snapshot of the\nglass, leads to configurations that are rich of soft low-energy modes as well\nas unstable modes (negative eigenvalues) that are otherwise completely \"washed\nout\" and lost, if one lets the system relax after strain. This procedure is\nfully consistent with the structure of NALD. The INM spectrum of deformed\nstates allows for the analytical prediction of the stress-strain curve of a\nmodel glass, including the prediction of the yield point. Good parameter-free\nquantitative agreement is shown between the prediction and simulations of\nathermal quasi-static shear of a coarse-grained polymer glass.",
        "positive": "The main transition in the Pink membrane model: finite-size scaling and\n  the influence of surface roughness: We consider the main transition in single-component membranes using computer\nsimulations of the Pink model [D. Pink {\\it et al.}, Biochemistry {\\bf 19}, 349\n(1980)]. We first show that the accepted parameters of the Pink model yield a\nmain transition temperature that is systematically below experimental values.\nThis resolves an issue that was first pointed out by Corvera and co-workers\n[Phys. Rev. E {\\bf 47}, 696 (1993)]. In order to yield the correct transition\ntemperature, the strength of the van der Waals coupling in the Pink model must\nbe increased; by using finite-size scaling, a set of optimal values is\nproposed. We also provide finite-size scaling evidence that the Pink model\nbelongs to the universality class of the two-dimensional Ising model. This\nfinding holds irrespective of the number of conformational states. Finally, we\naddress the main transition in the presence of quenched disorder, which may\narise in situations where the membrane is deposited on a rough support. In this\ncase, we observe a stable multi-domain structure of gel and fluid domains, and\nthe absence of a sharp transition in the thermodynamic limit."
    },
    {
        "anchor": "Bistability in the Unstable Flow of Polymer Solutions Through Porous\n  Media: Polymer solutions are often injected in porous media for applications such as\noil recovery and groundwater remediation. As the fluid navigates the tortuous\npore space, elastic stresses build up, causing the flow to become unstable at\nsufficiently large injection rates. However, it is poorly understood how the\nspatial and temporal characteristics of this unstable flow depend on pore space\ngeometry. We elucidate this dependence by systematically varying the spacing\nbetween pore constrictions in a model porous medium. We find that when the pore\nspacing is large, unstable eddies form upstream of each pore, similar to\nobservations of an isolated pore. By contrast, when the pore spacing is\nsufficiently small, the flow exhibits a surprising bistability, stochastically\nswitching between two distinct unstable flow states. We hypothesize that this\nunusual behavior arises from the interplay between flow-induced polymer\nelongation and relaxation of polymers as they are advected through the porous\nmedium. Consistent with this idea, we find that the flow state in a given pore\npersists for long times. Moreover, we find that the flow state is correlated\nbetween neighboring pores; however, these correlations do not persist\nlong-range. Our results thus help to elucidate the rich array of flow behaviors\nthat can arise in polymer solution flow through porous media.",
        "positive": "Synthesis of multilamellar walls vesicles polyelectrolyte-surfactant\n  complexes from pH-stimulated phase transition using microbial biosurfactants: Multilamellar wall vesicles (MLWV) are an interesting class of\npolyelectrolyte-surfactant complexes (PESCs) for wide applications ranging from\nhouse-care to biomedical products. If MLWV are generally obtained by a\npolyelectrolyte-driven vesicle agglutination under pseudo-equilibrium\nconditions, the resulting phase is often a mixture of more than one structure.\nIn this work, we show that MLWV can be massively and reproductively prepared\nfrom a recently developed method involving a pH-stimulated phase transition\nfrom a complex coacervate phase (Co). We employ a biobased pH-sensitive\nmicrobial glucolipid biosurfactant in the presence of a natural, or synthetic,\npolyamine (chitosan, poly-L-Lysine, polyethylene imine, polyallylamine). In\nsitu small angle X-ray scattering (SAXS) and cryogenic transmission electron\nmicroscopy (cryo-TEM) show a systematic isostructural and isodimensional\ntransition from the Co to the MLWV phase, while optical microscopy under\npolarized light experiments and cryo-TEM reveal a massive, virtually\nquantitative, presence of MLWV. Finally, the multilamellar wall structure is\nnot perturbed by filtration and sonication, two typical methods employed to\ncontrol size distribution in vesicles. In summary, this work highlights a new,\nrobust, non-equilibrium phase-change method to develop biobased multilamellar\nwall vesicles, promising soft colloids with applications in the field of\npersonal care, cosmetics and pharmaceutics among many others."
    },
    {
        "anchor": "Circular motion of asymmetric self-propelling particles: Micron-sized self-propelled (active) particles can be considered as model\nsystems for characterizing more complex biological organisms like swimming\nbacteria or motile cells. We produce asymmetric microswimmers by soft\nlithography and study their circular motion on a substrate and near channel\nboundaries. Our experimental observations are in full agreement with a theory\nof Brownian dynamics for asymmetric self-propelled particles, which couples\ntheir translational and orientational motion.",
        "positive": "Physics of liquid crystals in cell biology: The last decade has witnessed a rapid growth in understanding of the pivotal\nroles of mechanical stresses and physical forces in cell biology. As a result\nan integrated view of cell biology is evolving, where genetic and molecular\nfeatures are scrutinized hand in hand with physical and mechanical\ncharacteristics of cells. Physics of liquid crystals has emerged as a\nburgeoning new frontier in cell biology over the past few years, fueled by an\nincreasing identification of orientational order and topological defects in\ncell biology, spanning scales from subcellular filaments to individual cells\nand multicellular tissues. Here, we provide an account of most recent findings\nand developments together with future promises and challenges in this rapidly\nevolving interdisciplinary research direction."
    },
    {
        "anchor": "Rupture of DNA Aptamer: new insights from simulations: Base-pockets (non-complementary base-pairs) in a double-stranded DNA play a\ncrucial role in biological processes. Because of thermal fluctuations, it can\nlower the stability of DNA, whereas, in case of DNA aptamer, small molecules\ne.g. adenosinemonophosphate(AMP), adenosinetriphosphate(ATP) etc, form\nadditional hydrogen bonds with base-pockets termed as \"binding-pockets\", which\nenhance the stability. Using the Langevin Dynamics simulations of coarse\ngrained model of DNA followed by atomistic simulations, we investigated the\ninfluence of base-pocket and binding-pocket on the stability of DNA aptamer.\nStriking differences have been reported here for the separation induced by\ntemperature and force, which require further investigation by single molecule\nexperiments.",
        "positive": "Bridging the Gap: 3D Real-Space Characterization of Colloidal Assemblies\n  via FIB-SEM Tomography: Insight in the structure of nanoparticle assemblies up to a single particle\nlevel is key to understand the collective properties of these assemblies, which\ncritically depend on the individual particle positions and orientations.\nHowever, the characterization of large, micron sized assemblies containing\nsmall, 10-500 nanometer, sized colloids is highly challenging and cannot easily\nbe done with the conventional light, electron or X-ray microscopy techniques.\nHere, we demonstrate that focused ion beam-scanning electron microscopy\n(FIB-SEM) tomography in combination with image processing enables quantitative\nreal-space studies of ordered and disordered particle assemblies too large for\nconventional transmission electron tomography, containing particles too small\nfor confocal microscopy. First, we demonstrate the high resolution structural\nanalysis of spherical nanoparticle assemblies, containing small anisotropic\ngold nanoparticles. Herein, FIB-SEM tomography allows the characterization of\nassembly dimensions which are inaccessible to conventional transmission\nelectron microscopy. Next, we show that FIB-SEM tomography is capable of\ncharacterizing much larger ordered and disordered assemblies containing silica\ncolloids with a diameter close to the resolution limit of confocal microscopes.\nWe determined both the position and the orientation of each individual\n(nano)particle in the assemblies by using recently developed particle tracking\nroutines. Such high precision structural information is essential in the\nunderstanding and design of the collective properties of new nanoparticle based\nmaterials and processes."
    },
    {
        "anchor": "Mechanical, adhesive and thermodynamic properties of hollow\n  nanoparticles: When sheets of layered material like C, WS$_2$ or BN are restricted to finite\nsizes, they generally form single- and multi-walled hollow nanoparticles in\norder to avoid dangling bonds. Using continuum approaches to model elastic\ndeformation and van der Waals interactions of spherical nanoparticles, we\npredict the variation of mechanical stability, adhesive properties and phase\nbehavior with radius $R$ and thickness $h$. We find that mechanical stability\nis limited by forces in the nN range and pressures in the GPa range. Adhesion\nenergies scale linearly with $R$, but depend only weakly on $h$. Deformation\ndue to van der Waals adhesion occurs for single-walled particles for radii of\nfew nm, but is quickly suppressed for increasing thickness. As $R$ is\nincreased, the gas-liquid coexistence disappears from the phase diagram for\nparticle radii in the range of 1-3 nm (depending on wall thickness) since the\ninteraction range decreases like 1/R.",
        "positive": "The carnivorous plant Genlisea harnesses active particle dynamics to\n  prey on microfauna: Carnivory in plants is an unusual trait that has arisen multiple times,\nindependently, throughout evolutionary history. Plants in the genus Genlisea\nare carnivorous, and feed on microorganisms that live in soil using modified\nsubterranean leaf structures (rhizophylls). A surprisingly broad array of\nmicrofauna has been observed in the plants' digestive chambers, including\nciliates, amoebae and soil mites. Here we show, through experiments and\nsimulations, that Genlisea exploit active matter physics to 'rectify' bacterial\nswimming and establish a local flux of bacteria through the structured\nenvironment of the rhizophyll towards the plant's digestion vesicle. In\ncontrast, macromolecular digestion products are free to diffuse away from the\ndigestion vesicle and establish a concentration gradient of carbon sources to\ndraw larger microorganisms further inside the plant. Our experiments and\nsimulations show that this mechanism is likely to be a localised one, and that\nno large-scale efflux of digested matter is present."
    },
    {
        "anchor": "Nonlinear elasticity of composite networks of stiff biopolymers with\n  flexible linkers: Motivated by recent experiments showing nonlinear elasticity of in vitro\nnetworks of the biopolymer actin cross-linked with filamin, we present an\neffective medium theory of flexibly cross-linked stiff polymer networks. We\nmodel such networks by randomly oriented elastic rods connected by flexible\nconnectors to a surrounding elastic continuum, which self-consistently\nrepresents the behavior of the rest of the network. This model yields a\ncrossover from a linear elastic regime to a highly nonlinear elastic regime\nthat stiffens in a way quantitatively consistent with experiment.",
        "positive": "Concentration Dependence of Excluded Volume Effects: The concentration dependence of the excluded volume effects in polymer\nsolutions is investigated. Through thermodynamic arguments for the\ninterpenetration of polymer segments and the free energy change, we show that\nthe disappearance of the excluded volume effects should occur at medium\nconcentration. The result is in accord with the recent experimental\nobservations."
    },
    {
        "anchor": "Infrared Optical Spectroscopy of Molten Fluorides: Methods, Electronic\n  and Vibrational Data, Structural Interpretation, and Relevance to Radiative\n  Heat Transfer: To help address the need for predicting radiative heat transfer (RHT)\nbehavior of molten salts, we conducted a comprehensive review of methods and\ndata from infrared optical spectroscopic measurements on molten fluoride salts.\nTransmittance, reflectance, and trans-reflectance experimental methods are\ndiscussed, along with the corresponding data reduction methodology and the\nlimitations of each technique. Optical spectroscopy is a convenient indirect\nprobe for changes in structural parameters with temperature and composition.\nElectronic and vibrational absorption data for transition-metal, lanthanide,\nand actinide solutes and vibrational absorption data for alkali and alkaline\nearth fluoride solvents are compiled, and the corresponding structural\ninterpretation is discussed and compared with other experimental and\ntheoretical work. We find that solvent and solute vibrational absorption can be\nsignificant in the mid-infrared, resulting in near-infrared edges of\nsignificance to RHT. Extrapolation and averaging of existing edge data leads to\nestimated gray absorption coefficient values at 700 degrees C of 493 m^(-1) for\nFLiBe and 148 m^(-1) for FLiNaK, both within the range of 1 to 6000 m^(-1)\nidentified to be of engineering relevance for radiative heat transfer analysis.",
        "positive": "Blistering Failure of Elastic Coatings with Applications to Corrosion\n  Resistance: A variety of polymeric surfaces, such as anti-corrosion coatings and\npolymer-modified asphalts, are prone to blistering when exposed to moisture and\nair. As water and oxygen diffuse through the material, dissolved species are\nproduced, which generate osmotic pressure that deforms and debonds the\ncoating.These mechanisms are experimentally well-supported; however,\ncomprehensive macroscopic models capable of predicting the formation osmotic\nblisters, without extensive data-fitting, is scant. Here, we develop a general\nmathematical theory of blistering and apply it to the failure of anti-corrosion\ncoatings on carbon steel. The model is able to predict the irreversible,\nnonlinear blister growth dynamics, which eventually reaches a stable state,\nruptures, or undergoes runaway delamination, depending on the mechanical and\nadhesion properties of the coating. For runaway delamination, the theory\npredicts a critical delamination length, beyond which unstable corrosion-driven\ngrowth occurs. The model is able to fit multiple sets of blister growth data\nwith no fitting parameters. Corrosion experiments are also performed to observe\nundercoat rusting on carbon steel, which yielded trends comparable with model\npredictions. The theory is used to define three dimensionless numbers which can\nbe used for engineering design of elastic coatings capable of resisting visible\ndeformation, rupture, and delamination."
    },
    {
        "anchor": "Transport and Diffusion Enhancement in Experimentally Realized\n  Non-Gaussian Correlated Ratchets: Living cells are known to generate non-Gaussian active fluctuations\nsignificantly larger than thermal fluctuations owing to various active\nprocesses. Understanding the effect of these active fluctuations on various\nphysicochemical processes, such as the transport of molecular motors, is a\nfundamental problem in nonequilibrium physics. Therefore, we experimentally and\nnumerically study an active Brownian ratchet comprising a colloidal particle in\nan optically generated asymmetric periodic potential driven by non-Gaussian\nnoise having finite-amplitude active bursts, each arriving at random and\ndecaying exponentially. We find that the particle velocity is maximum for\nrelatively sparse bursts with finite correlation time and non-Gaussian\ndistribution. These occasional kicks, which produce Brownian yet non-Gaussian\ndiffusion, are more efficient for transport and diffusion enhancement of the\nparticle than the incessant kicks of active Ornstein-Uhlenbeck noise.",
        "positive": "The influence of line tension on the formation of liquid bridges in\n  atomic force microscope-like geometry: The phase diagram of a fluid confined between a planar and a conical walls\nmodelling the atomic force microscope geometry displays transition between two\nphases, one with a liquid bridge connecting the two walls of the microscope,\nand the other without bridge. The structure of the corresponding coexistence\nline is determined and its dependence on the value of the line tension\ncoefficient is discussed."
    },
    {
        "anchor": "Inverse design of artificial skins: Mimicking the perceptual functions of human cutaneous mechanoreceptors,\nartificial skins or flexible pressure sensors can transduce tactile stimuli to\nquantitative electrical signals. Conventional methods to design such devices\nfollow a forward structure-to-property routine based on trial-and-error\nexperiments/simulations, which take months or longer to determine one solution\nvalid for one specific material. Target-oriented inverse design that shows far\nhigher output efficiency has proven effective in other fields, but is still\nabsent for artificial skins because of the difficulties in acquiring big data.\nHere, we report a property-to-structure inverse design of artificial skins\nbased on small dataset machine learning, exhibiting a comprehensive efficiency\nat least four orders of magnitude higher than the conventional routine. The\ninverse routine can predict hundreds of solutions that overcome the intrinsic\nsignal saturation problem for linear response in hours, and the solutions are\nvalid to a variety of materials. Our results demonstrate that the inverse\ndesign allowed by small dataset is an efficient and powerful tool to target\nmultifarious applications of artificial skins, which can potentially advance\nthe fields of intelligent robots, advanced healthcare, and human-machine\ninterfaces.",
        "positive": "Extinction Transition on a Pie: Extinction transition of bacteria under forced rotation is analyzed in pie\ngeometry. Under convection, separation of the radial and the azimuthal degrees\nof freedom is not possible, and the linearized evolution operator is\ndiagonalized numerically. Some characteristics scales are compared with the\nresults of recent experiments, and the ``integrable'' limit of the theory at\nnarrow growth region is analyzed."
    },
    {
        "anchor": "Local contact numbers in two dimensional packings of frictional disks: We analyze the local structure of two dimensional packings of frictional\ndisks numerically. We focus on the fractions x_i of particles that are in\ncontact with i neighbors, and systematically vary the confining pressure p and\nfriction coefficient \\mu. We find that for all \\mu, the fractions x_i exhibit\npowerlaw scaling with p, which allows us to obtain an accurate estimate for x_i\nat zero pressure. We uncover how these zero pressure fractions x_i vary with\n\\mu, and introduce a simple model that captures most of this variation. We also\nprobe the correlations between the contact numbers of neighboring particles.",
        "positive": "Experimentally Testing a Generalized Coarsening Model for Individual\n  Bubbles in Quasi-Two-Dimensional Wet Foams: We present high-precision data for the time evolution of bubble area $A(t)$\nand circularity shape parameter $C(t)$ for quasi-2d foams consisting of bubbles\nsquashed between parallel plates. In order to fully compare with predictions by\nRoth et al. [Phys. Rev. E 87 2013] and Schimming et al. [Phys. Rev. E 96 2017],\nfoam wetness is systematically varied by controlling the height of the sample\nabove a liquid reservoir which in turn controls the radius $r$ of the inflation\nof the Plateau borders. For very dry foams, where the borders are very small,\nclassic von Neumann behavior is observed where a bubble's growth rate depends\nonly on its number $n$ of sides. For wet foams, the inflated borders impede gas\nexchange and cause deviations from von Neumann's law that are found to be in\naccord with the generalized coarsening equation. In particular, the overall\ngrowth rate varies linearly with the film height, which decrease as surface\nPlateau borders inflate. And, more interestingly, the deviation from\n$dA/dt\\propto (n-6)$ von Neumann behavior grows in proportion to\n$nCr/\\sqrt{A}$. This is highlighted definitively by data for six-sided bubbles,\nwhich are forbidden to grow or shrink except for the existence of this term.\nAnd it is tested quantitatively by variation of all four relevant quantities:\n$n$, $C$, $r$, and $A$"
    },
    {
        "anchor": "Binding potential and wetting behaviour of binary liquid mixtures on\n  surfaces: We present a theory for the interfacial wetting phase behaviour of binary\nliquid mixtures on rigid solid substrates, applicable to both miscible and\nimmiscible mixtures. In particular, we calculate the binding potential as a\nfunction of the adsorptions, i.e. the excess amounts of each of the two liquids\nat the substrate. The binding potential fully describes the corresponding\ninterfacial thermodynamics. Our approach is based on classical density\nfunctional theory. Binary liquid mixtures can exhibit complex bulk phase\nbehaviour, including both liquid-liquid and vapour-liquid phase separation,\ndepending on the nature of the interactions between all the particles of the\ntwo different liquids, the temperature and the chemical potentials. Here we\nshow that the interplay between the bulk phase behaviour of the mixture and the\nproperties of the interactions with the substrate gives rise to a wide variety\nof interfacial phase behaviours, including mixing and demixing situations. We\nfind situations where the final state is a coexistence of up to three different\nphases. We determine how the liquid density profiles close to the substrate\nchange as the interaction parameters are varied and how these determine the\nform of the binding potential, which in certain cases can be a multi-valued\nfunction of the adsorptions. We also present profiles for sessile droplets of\nboth miscible and immiscible binary liquids.",
        "positive": "A quantitative analysis of the emergence of memory in the viscously\n  coupled dynamics of colloids: We provide a quantitative description of the evolution of memory from the\napparently random Markovian dynamics of a pair of optically trapped colloidal\nmicroparticles in water. The particles are trapped in very close proximity of\neach other so that the resultant hydrodynamic interactions lead to\nnon-Markovian signatures manifested by the double exponential auto-correlation\nfunction for the Brownian motion of each particle. In connection with the\nemergence of memory in this system, we quantify the storage of energy and\ndemonstrate that a pair of Markovian particles - confined in individual optical\ntraps in a viscous fluid - can be described in the framework of a single\nBrownian particle in a viscoelastic medium. We define and quantify the\nequivalent storage and loss moduli of the two-particle system, and show\nexperimentally that the memory effects reduce with increasing particle\nseparation and increase with a skewed stiffness ratio between the traps."
    },
    {
        "anchor": "Ion filling of a one-dimensional nanofluidic channel in the interaction\n  confinement regime: Ion transport measurements are widely used as an indirect probe for various\nproperties of confined electrolytes. It is generally assumed that the ion\nconcentration in a nanoscale channel is equal to the ion concentration in the\nmacroscopic reservoirs it connects to, with deviations arising only in the\npresence of surface charges on the channel walls. Here, we show that this\nassumption may break down even in a neutral channel, due to electrostatic\ncorrelations between the ions arising in the regime of interaction confinement,\nwhere Coulomb interactions are reinforced due to the presence of the channel\nwalls. We focus on a one-dimensional channel geometry, where an exact\nevaluation of the electrolyte's partition function is possible with a transfer\noperator approach. Our exact solution reveals that in nanometre-scale channels,\nthe ion concentration is generally lower than in the reservoirs, and depends\ncontinuously on the bulk salt concentration, in contrast to conventional\nmean-field theory that predicts an abrupt filling transition. We develop a\nmodified mean-field theory taking into account the presence of ion pairs that\nagrees quantitatively with the exact solution and provides predictions for\nexperimentally-relevant observables such as the ionic conductivity. Our results\nwill guide the interpretation of nanoscale ion transport measurements.",
        "positive": "Linear Viscoelasticity of Soft Glassy Materials: Owing to lack of time translational invariance, aging soft glassy materials\ndo not obey fundamental principles of linear viscoelasticity. We show that by\ntransforming the linear viscoelastic framework from the real time domain to the\neffective time domain, wherein the material clock is readjusted to account for\nevolution of relaxation time, the soft glassy materials obey effective time\ntranslational invariance. Consequently, we demonstrate successful validation of\nprinciples of linear viscoelasticity (Boltzmann superposition principle and\nconvolution relation for creep compliance and stress relaxation modulus) for\ndifferent types of soft glassy materials in the effective time domain."
    },
    {
        "anchor": "Rectified motion of short polymer chain that walks along a ratchet\n  potential that coupled with spatially varying temperature: We explore the transport features of a single flexible polymer chain that\nwalks on a periodic ratchet potential coupled with spatially varying\ntemperature. At steady state the polymer exhibits a fast unidirectional motion\nwhere the intensity of its current rectification depends strongly on its\nelastic strength and size. Analytic and numerical analysis reveal that the\nsteady state transport of the polymer can be controlled by attenuating the\nstrength of the elastic constant. Furthermore, the stall force at which the\nchain current vanishes is independent of the chain length and coupling\nstrength. Far from the stall force the mobility of the chain is strongly\ndependent on its size and flexibility. These findings show how the mobility of\na polymer can be controlled by tuning system parameters, and may have novel\napplications for polymer transport and sorting of multicomponent systems based\non their dominant parameters.",
        "positive": "Evolution of fragment size distributions from the crushing of granular\n  materials: We study the fragment size distributions after crushing of single and many\nparticles under uniaxial compression inside a cylindrical container by means of\nnumerical simulations. Under the assumption that breaking goes through the bulk\nof the particle we obtain the size distributions of fragments for both cases\nafter large displacements. For the single particle crushing, this fragmentation\nmechanism produces a log-normal size distribution, which deviates from the\npower-law distribution of fragment sizes for the packed bed. We show that as\nthe breaking process evolves, a power-law dependency on the displacement is\npresent for the single grain, while for the many grains system, the\ndistribution converges to a steady state. We further investigate the force\nnetworks and the average coordination number as a function of the particle\nsize, which gives inside about the origin of the power-law distributions for\nthe granular assembly under uniaxial compression."
    },
    {
        "anchor": "Gold nanoparticle supracrystals mechanics under pressure: the role of\n  the soft matrix: Nanocrystals, used as building blocks, may self-assemble in long-range\nordered assemblies socalled supracrystals. Different structures FCC, BCC but\nalso Frank-Kasper phases have been observed and the roles of the soft ligands\nsurrounding the rigid crystalline cores in the self-assembly process is not yet\nwell understood and need further study. The mechanical behavior under\nhydrostatic pressure of 3D single FCC crystals built by gold nanoparticles has\nbeen investigated using HP-SAXS and compared with pure alkane, corresponding to\nthe ligand chain. No structural transition has been observed up to 12 GPa, but\na large increase of the supracrystals bulk modulus has been measured.",
        "positive": "Wetting in a two-dimensional capped capillary. Part II: Three-phase\n  coexistence: In Part II of this study we consider two cases of three-phase coexistence.\nFirst, the capped capillary may allow for vapour, drop-like, and slab-like\nphases to coexist at the same values of temperature and chemical potential.\nSecond, the slit pore forming the bulk of the capped capillary may allow for\nthe coexistence between vapour, planar prewetting film and capillary-liquid.\nWhile the consideration of the former case allows us to summarise the\nphenomenology presented in Part I and to show that the transition line of wedge\nprewetting is shifted in capillary-like geometries by a constant value,\ndepending on the capillary width, the careful examination of the latter case\nallows us to uncover a new phase transition in confined fluids, a continuous\nplanar prewetting transition. A planar prewetting transition is known to be a\ndistinctly first-order phenomenon, and typically taking place on the scale of\nseveral atomic diameters. A continuous prewetting transition, on the other\nhand, is scale invariant. Thus, apart from being of fundamental significance,\nthis finding has potential for facilitating experimental detection as well as\nmeasurements of planar prewetting. Further, we provide proof for the existence\nof a tri-critical point of the three-phase coexistence line of the capped\ncapillary while by considering a dynamic model of wetting we show how the\nrelaxation of the system can be pinned by a metastable state. We present a full\nparametric study of our model system and support our findings with exhaustive\nexamples of density profiles, adsorption and free energy isotherms, and full\nphase diagrams."
    },
    {
        "anchor": "Spontaneous Directional Motion of Shaped Nanoparticle: In nanoscale space and pico- to nanoseconds enormous physical, chemical and\nbiological processes take place, while the motions of involved\nparticles/molecules under thermal fluctuations are usually analyzed using the\nconventional theory of diffusive Brownian motion based on both sufficiently\nlong time averaging and assumptions of spherical particle shapes. Here, using\nmolecular dynamics simulations, we show that asymmetrically shaped\nnanoparticles in dilute solutions possess spontaneous directional motion of the\ncenter of mass within a finite time interval. The driving force for this\nunexpected directional motion lies in the imbalance of the interactions\nexperienced by their constituent atoms during the orientation regulation at\ntimescales before the onset of diffusive Brownian motion. Theoretical formulae\nhave been derived to describe the mean displacement and the variance of this\ndirectional motion. Our study potentially takes an important step towards\nestablishing a complete theoretical framework for describing the motions of\nvariously-shaped particles in solutions over all timescales from ballistic to\ndiffusive regime.",
        "positive": "Variational bound on energy dissipation in turbulent shear flow: We present numerical solutions to the extended Doering-Constantin variational\nprinciple for upper bounds on the energy dissipation rate in plane Couette\nflow, bridging the entire range from low to asymptotically high Reynolds\nnumbers. Our variational bound exhibits structure, namely a pronounced minimum\nat intermediate Reynolds numbers, and recovers the Busse bound in the\nasymptotic regime. The most notable feature is a bifurcation of the minimizing\nwavenumbers, giving rise to simple scaling of the optimized variational\nparameters, and of the upper bound, with the Reynolds number."
    },
    {
        "anchor": "Memory of rheological stress in polymers using Fractional Calculus: The rheological properties of viscoelastic materials like polymer melts are\ngreatly affected by factors like salinity, temperature, concentration and pH of\nthe solution. In this study, the memory of the stress affected by each of these\nfactors is shown to be trapped in the order of the fractional derivative of the\ndynamical equation describing stress and strain in the material. To demonstrate\nthis, the rheological properties of the polymer melt hydrolyzed polyacrylamide\nHPAM have been modeled using a two element Maxwell model. The model has\nsuccessfully reproduce existing experimental data on elastic modulus and\ncomplex viscosity for these stress factors, besides predicting the development\nof creep compliance with shear rate. The work also establishes that it is\npossible to tailor a particular rheological property by suitably tuning a pair\nof properties, complementary conjugates, that offset each others effects on the\nrheology. The study shows that HPAM has at least two pairs of complementary\nconjugates in temperature and pH, and concentration and pH. Further it is shown\nthat the variation of viscosity with shear rate shows a power law behavior for\nalmost all variations in stress parameters. Our modelling using fractional\ncalculus establishes that the fractional order derivative q which is recognized\nas a memory index to emergent phenomena, shows an inverse relationship with\nrespect to the power law exponent a, the higher the memory index q, the smaller\nis the power-law exponent a.",
        "positive": "Correction of Wall Adhesion Effects in Batch Settling of Strong\n  Colloidal Gels: The batch settling test is widely used to estimate the compressive rheology\nof strongly flocculated colloidal suspensions, in particular the compressive\nyield strength and hydraulic permeability. Recently it has been discovered that\nwall adhesion effects in these tests may be significantly greater than\npreviously appreciated, which can introduce unbounded errors in the estimation\nof these rheological functions. Whilst a methodology to solve the underlying\nstatic problem and correct for wall adhesion effects has been developed, this\nmethod is quite complex and unwieldy, involving solution of a 2D hyper-elastic\nconstitutive model for strong colloidal gels. In this paper we develop a highly\nsimplified 1D visco-plastic approximation to the hyper-elastic model which\nadmits analytic expressions for the equilibrium solids concentration profile\nand bed height. These expressions facilitate robust estimation of the\ncompressive yield and wall adhesion strength via nonlinear regression of\nexperimental data in the presence of small measurement errors."
    },
    {
        "anchor": "Simulation of Hierarchical Viscous Fingering Pattern in Lifting\n  Hele-Shaw Cell: Viscous fingers in the lifting Hele-Shaw cell form a hierarchical pattern due\nto competition between growing fingers in a converging geometry. If the\ndefending fluid is visco-plastic, a permanent three-dimensional pattern is\nformed, which is usually approximated as quasi-two-dimensional. We present here\na Monte-Carlo simulation which attempts to reproduce the real 3-dimensional\npattern in rectangular geometry using a very simple algorithm. We study the\nfinger length distribution, the rate of increase of coverage of the invading\nfluid, the height profile of the final pattern and observe how these change\nwith characteristics of the fluids.",
        "positive": "Shape-tension coupling produces nematic order in an epithelium vertex\n  model: We study the vertex model for epithelial tissue mechanics extended to include\ncoupling between the cell shapes and tensions in cell-cell junctions. This\ncoupling represents an active force which drives the system out of equilibrium\nand leads to the formation of nematic order interspersed with prominent,\nlong-lived $+1$ defects. The defects in the nematic ordering are coupled to the\nshape of the cell tiling, affecting cell areas and coordinations. This\nintricate interplay between cell shape, size, and coordination provides a\npossible mechanism by which tissues could spontaneously develop long-range\npolarity through local mechanical forces without resorting to long-range\nchemical patterning."
    },
    {
        "anchor": "Surface tension of liquids near the critical point: A simple analytical microscopic expression for the surface tension of liquids\n$\\gamma$ is obtained which is in a good agreement with available data of\nnumerical experiments. We apply the integral transformation that maps the fluid\nHamiltonian onto the field-theoretical Hamiltonian and show that the order\nparameter of the effective Hamiltonian corresponds to the one-body potential in\nthe fluid. Revealing the physical meaning of the order parameter allows\ncalculation of $\\gamma$.",
        "positive": "Non-Faradaic electric currents in the Nernst-Planck equations and\n  'action at a distance' diffusiophoresis in crossed salt gradients: In the Nernst-Planck equations in two or more dimensions, a non-Faradaic\nelectric current can arise as a consequence of connecting patches with\ndifferent liquid junction potentials. Whereas this current vanishes for binary\nelectrolytes or one-dimensional problems, it is in general non-vanishing for\nexample in crossed salt gradients. For a suspended colloidal particle,\nelectrophoresis in the corresponding electrostatic potential gradient is\ngenerally vectorially misaligned with chemiphoresis in the concentration\ngradients, and diffusiophoresis (via electrophoresis) can occur in regions\nwhere there are no local concentration gradients ('action at a distance').\nThese phenomena may provide new opportunities to manipulate and sort particles,\nin microfluidic devices for example."
    },
    {
        "anchor": "Nonequilibrium design strategies for functional colloidal assemblies: We use a nonequilibrium variational principle to optimize the steady-state,\nshear-induced interconversion of self-assembled nanoclusters of DNA-coated\ncolloids. Employing this principle within a stochastic optimization algorithm\nallows us to discover design strategies for functional materials. We find that\nfar-from-equilibrium shear flow can significantly enhance the flux between\nspecific colloidal states by decoupling trade-offs between stability and\nreactivity required by systems in equilibrium. For isolated nanoclusters, we\nfind nonequilibrium strategies for amplifying transition rates by coupling a\ngiven reaction coordinate to the background shear flow. We also find that shear\nflow can be made to selectively break detailed balance and maximize probability\ncurrents by coupling orientational degrees of freedom to conformational\ntransitions. For a microphase consisting of many nanoclusters, we study the\nflux of colloids hopping between clusters. We find that a shear flow can\namplify the flux without a proportional compromise on the microphase structure.\nThis approach provides a general means of uncovering design principles for\nnanoscale, autonomous, functional materials driven far from equilibrium.",
        "positive": "Connecting water correlations, fluctuations, and wetting phenomena at\n  hydrophobic and hydrophilic surfaces: We use molecular simulations to demonstrate the connection between transverse\nwater-water correlations and wetting phenomena for a range of hydrophobic to\nhydrophilic solid surfaces.Near superhydrophobic surfaces, the correlations are\nlong ranged, system spanning, and are well described by the capillary wave\ntheory. With increasing surface-water attractions, the correlations are\nquenched. At the critical attraction at which long range correlations\ndisappear, the density profile normal to the surface changes from sigmoidal to\nlayered, and the fluid begins to wet the surface. This behavior is displayed by\nboth water and a Lennard-Jones fluid, highlighting the universality of the\nunderlying physics."
    },
    {
        "anchor": "Rheological Chaos in a Scalar Shear-Thickening Model: We study a simple scalar constitutive equation for a shear-thickening\nmaterial at zero Reynolds number, in which the shear stress \\sigma is driven at\na constant shear rate \\dot\\gamma and relaxes by two parallel decay processes: a\nnonlinear decay at a nonmonotonic rate R(\\sigma_1) and a linear decay at rate\n\\lambda\\sigma_2. Here \\sigma_{1,2}(t) =\n\\tau_{1,2}^{-1}\\int_0^t\\sigma(t')\\exp[-(t-t')/\\tau_{1,2}] {\\rm d}t' are two\nretarded stresses. For suitable parameters, the steady state flow curve is\nmonotonic but unstable; this arises when \\tau_2>\\tau_1 and\n0>R'(\\sigma)>-\\lambda so that monotonicity is restored only through the\nstrongly retarded term (which might model a slow evolution of material\nstructure under stress). Within the unstable region we find a period-doubling\nsequence leading to chaos. Instability, but not chaos, persists even for the\ncase \\tau_1\\to 0. A similar generic mechanism might also arise in shear\nthinning systems and in some banded flows.",
        "positive": "Carbon Nanotubes as Electrodes for Dielectrophoresis of DNA: Dielectrophoresis can potentially be used as an efficient trapping tool in\nthe fabrication of molecular devices. For nanoscale objects, however, the\nBrownian motion poses a challenge. We show that the use of carbon nanotube\nelectrodes makes it possible to apply relatively low trapping voltages and\nstill achieve high enough field gradients for trapping nanoscale objects, e.g.,\nsingle molecules. We compare the efficiency and other characteristics of\ndielectrophoresis between carbon nanotube electrodes and lithographically\nfabricated metallic electrodes, in the case of trapping nanoscale DNA\nmolecules. The results are analyzed using finite element method simulations and\nreveal information about the frequency dependent polarizability of DNA."
    },
    {
        "anchor": "Unified theoretical and experimental view on transient shear banding: Dense emulsions, colloidal gels, microgels, and foams all display a\nsolid-like behavior at rest characterized by a yield stress, above which the\nmaterial flows like a liquid. Such a fluidization transition often consists of\nlong-lasting transient flows that involve shear-banded velocity profiles. The\ncharacteristic time for full fluidization, $\\tau_\\text{f}$, has been reported\nto decay as a power-law of the shear rate $\\dot \\gamma$ and of the shear stress\n$\\sigma$ with respective exponents $\\alpha$ and $\\beta$. Strikingly, the ratio\nof these exponents was empirically observed to coincide with the exponent of\nthe Herschel-Bulkley law that describes the steady-state flow behavior of these\ncomplex fluids. Here we introduce a continuum model, based on the minimization\nof a \"free energy\", that captures quantitatively all the salient features\nassociated with such \\textit{transient} shear-banding. More generally, our\nresults provide a unified theoretical framework for describing the yielding\ntransition and the steady-state flow properties of yield stress fluids.",
        "positive": "Ferrohydrodynamics: testing a new magnetization equation: A new magnetization equation recently derived from irreversible\nthermodynamics is employed to the calculation of an increase of ferrofluid\nviscosity in a magnetic field. Results of the calculations are compared with\nthose obtained on the basis of two well-known magnetization equations. One of\nthe two was obtained phenomenologically, another one was derived\nmicroscopically from the Fokker-Planck equation. It is shown that the new\nmagnetization equation yields a quite satisfactory description of\nmagnetiviscosity in the entire region of magnetic field strength and the flow\nvorticity. This equation turns out to be valid -- like the microscopically\nderived equation but unlike the former phenomenological equation -- even far\nfrom equilibrium, and so it should be recommended for further applications."
    },
    {
        "anchor": "Morphological changes of amphiphilic molecular assemblies induced by\n  chemical reaction: Shape transformations of amphiphilic molecular assemblies induced by chemical\nreaction are studied using coarse-grained molecular simulations. A binding\nreaction between hydrophilic and hydrophobic molecules is considered. It is\nfound that the reaction induces transformation of an oil droplet to a tubular\nvesicle via bicelles and vesicles with discoidal arms. The discoidal arms close\ninto vesicles, which are subsequently fused into the tubular vesicle. Under the\nchemical reaction, the bicelle-to-vesicle transition occurs at smaller sizes\nthan in the absence of the hydrophobic molecules. It is revealed that the\nenhancement of this transition is due to embedded hydrophobic particles that\nreduce the membrane bending rigidity.",
        "positive": "Emergence of two-level systems in glass formers: a kinetic Monte Carlo\n  study: Using a distinguishable-particle lattice model based on void-induced\ndynamics, we successfully reproduce the well-known linear relation between heat\ncapacity and temperature at very low temperatures. The heat capacity is\ndominated by two-level systems formed due to the strong localization of voids\nto two neighboring sites, and can be exactly calculated in the limit of\nultrastable glasses. Similar but weaker localization at higher temperatures\naccounts for the glass transition. The result supports the conventional\ntwo-level tunneling picture by revealing how two-level systems emerge from\nrandom particle interactions, which also cause the glass transition. Our\napproach provides a unified framework for relating microscopic dynamics of\nglasses at room and cryogenic temperatures."
    },
    {
        "anchor": "Antifouling membranes for oily wastewater treatment: interplay between\n  wetting and membrane fouling: Oily wastewater is an extensive source of pollution to soil and water, and\nits harmless treatment is of great importance for the protection of our aquatic\necosystems. Membrane filtration is highly desirable for removing oil from oily\nwater because it has the advantages of energy efficiency, easy processing and\nlow maintenance cost. However, membrane fouling during filtration leads to\nsevere flux decline and impedes long-term operation of membranes in practical\nwastewater treatment. Membrane fouling includes reversible fouling and\nirreversible fouling. The fouling mechanisms have been explored based on\nclassical fouling models, and on oil droplet behaviors (such as droplet\ndeposition, accumulation, coalescence and wetting) on the membranes. Membrane\nfouling is dominated by droplet-membrane interaction, which is influenced by\nthe properties of the membrane (e.g., surface chemistry, structure and charge)\nand the wastewater (e.g., compositions and concentrations) as well as the\noperation conditions. Typical membrane antifouling strategies, such as surface\nhydrophilization, zwitterionic polymer coating, photocatalytic decomposition\nand electrically enhanced antifouling are reviewed, and their cons and pros for\npractical applications are discussed.",
        "positive": "Tree frog-inspired nanopillar arrays for enhancement of adhesion and\n  friction: Bioinspired structure adhesives have received increasing interest for many\napplications, such as climbing robots and medical devices. Inspired by the\nclosely packed keratin nanopillars on the toe pads of tree frogs, tightly\narranged polycaprolactone nanorod arrays are prepared by mold process and\nchemical modification. Nanorod arrays show enhanced adhesion and friction on\nboth smooth and rough surfaces compared to the arrays with hexagonal\nmicropillars. The bonding of nanorods results in a larger stiffness of the\nnanorod surface,contributing mainly to friction rather than adhesion. The\nresults suggest the function of closely packed keratin nanopillars on the toe\npad of tree frogs and offer a guiding principle for the designing of new\nstructured adhesives with strong attaching abilities."
    },
    {
        "anchor": "Structure of propagating high stress fronts in a shear thickening\n  suspension: We report direct measurements of spatially resolved stress at the boundary of\na shear thickening cornstarch suspension revealing persistent regions of high\nlocal stress propagating in the flow direction at the speed of the top\nboundary. The persistence of these propagating fronts enables precise\nmeasurements of their structure, including the profile of boundary stress\nmeasured by Boundary Stress Microscopy (BSM) and the non-affine velocity of\nparticles at the bottom boundary of the suspension measured by particle image\nvelocimetry (PIV). In addition, we directly measure the relative flow between\nthe particle phase and the suspending fluid (fluid migration) and find the\nmigration is highly localized to the fronts and changes direction across the\nfront, indicating that the fronts are composed of a localized region of high\ndilatant pressure and low particle concentration. The magnitude of the flow\nindicates that the pore pressure difference driving the fluid migration is\ncomparable to the critical shear stress for the onset of shear thickening. The\npropagating fronts fully account for the increase in viscosity with applied\nstress reported by the rheometer and are consistent with the existence of a\nstable jammed region in contact with one boundary of the system that generates\na propagating network of percolated frictional contacts spanning the gap\nbetween the rheometer plates and producing strong localized dilatant pressure.",
        "positive": "Structural evolution of protein-biofilms: Simulations and Experiments: The control of biofilm formation is a challenging goal that has not been\nreached yet in many aspects. One is the role of van der Waals forces and\nanother the importance of mutual interactions between the adsorbing and the\nadsorbed biomolecules ('critical crowding'). Here, a combined exeperimental and\ntheoretical approach is presented that fundamentally probes both aspects. On\nthree model proteins, lysozyme, {\\alpha}-amylase and bovine serum albumin\n(BSA), the adsorption kinetics is studied. Composite substrates are used\nenabling a separation of the short- and the long-range forces. Though usually\nneglected, experimental evidence is given for the influence of van der Waals\nforces on the protein adsorption as revealed by in situ ellipsometry. The three\nproteins were chosen for their different conformational stability in order to\ninvestigate the influence of conformational changes on the adsorption kinetics.\nMonte Carlo simulations are used to develop a model for these experimental\nresults by assuming an internal degree of freedom to represent conformational\nchanges. The simulations also provide data on the distribution of adsorption\nsites. By in situ atomic force microscopy we can also test this distribution\nexperimentally which opens the possibility to e.g. investigate the interactions\nbetween adsorbed proteins."
    },
    {
        "anchor": "Invariance of the Local Segmental Relaxation Dispersion in\n  Polycyclohexylmethacrylate / Poly-alpha-Methylstyrene Blends: Dielectric spectroscopy was carried out on polycyclohexylmethacrylate (PCHMA)\nand its blend with poly-alpha-methylstyrene (PaMS) as a function of temperature\nand pressure. When measured at conditions whereby the local segmental\nrelaxation time for the PCHMA was constant, the dispersion in the loss spectra\nhad a fixed shape; that is, the relaxation time determines the breadth of the\nrelaxation time distribution, independently of T and P. This result is known\nfor neat materials and could be observed for the blend herein due to the\nnonpolar character of the PaMS and the degree of thermodynamic miscibility of\nthe blend.",
        "positive": "Transverse instability of dunes: The simplest type of dune is the transverse one, which propagates with\ninvariant profile orthogonally to a fixed wind direction. Here we show\nnumerically and with a linear stability analysis that transverse dunes are\nunstable with respect to along-axis perturbations in their profile and decay on\nthe bedrock into barchan dunes. Any forcing modulation amplifies exponentially\nwith growth rate determined by the dune turnover time. We estimate the distance\ncovered by a transverse dune before fully decaying into barchans and identify\nthe patterns produced by different types of perturbation."
    },
    {
        "anchor": "How roughness affects the depletion mechanism: We develop a simple model, in the spirit of the Asakura-Oosawa theory, able\nto describe the effects of surface roughness on the depletion potential as a\nfunction of a small set of parameters. The resulting explicit expressions are\neasily computed, without free parameters, for a wide range of physically\ninteresting conditions. Comparison with the recent numerical simulations [M.\nKamp et al., Langmuir, 2016, 32, 1233] shows an encouraging agreement and\nallows to predict the onset of colloidal aggregation in dilute suspensions of\nrough particles. Furthermore, the model proves to be suitable to investigate\nthe role of the geometry of the roughness.",
        "positive": "Unzipping Kinetics of Double-Stranded DNA in a Nanopore: We studied the unzipping kinetics of single molecules of double-stranded DNA\nby pulling one of their two strands through a narrow protein pore. PCR analysis\nyielded the first direct proof of DNA unzipping in such a system. The time to\nunzip each molecule was inferred from the ionic current signature of DNA\ntraversal. The distribution of times to unzip under various experimental\nconditions fit a simple kinetic model. Using this model, we estimated the\nenthalpy barriers to unzipping and the effective charge of a nucleotide in the\npore, which was considerably smaller than previously assumed."
    },
    {
        "anchor": "Anomalous glassy relaxation near the isotropic-nematic phase transition: Dynamical heterogeneity in a system of Gay-Berne ellipsoids near its\nisotropic-nematic (I-N) transition and also in an equimolar mixture of\nLennard-Jones spheres and Gay-Berne ellipsoids in deeply supercooled regime is\nprobed by the time evolution of non-Gaussian parameter (NGP). The appearance of\na dominant second peak in the rotational NGP near the I-N transition signals\nthe growth of pseudonematic domains. Surprisingly such a second peak is instead\nobserved in the translational NGP for glassy binary mixture. Localization of\norientational motion near the I-N transition is found to be responsible for the\nobserved anomalous orientational relaxation.",
        "positive": "Flexible Colloidal Molecules with Directional Bonds and Controlled\n  Flexibility: Colloidal molecules are ideal model systems for mimicking real molecules and\ncan serve as versatile building blocks for the bottom-up self-assembly of\nflexible and smart materials. While most colloidal molecules are rigid objects,\nthe development of colloidal joints has made it possible to also include\nconformational flexibility into colloidal molecules. However, their\nunrestricted range of motion does not capture the restricted motion range and\nbond directionality that is typical of real molecules.\n  In this work, we create flexible colloidal molecules with an in situ\ncontrollable motion range and bond directionality by assembling spherical\nparticles onto cubes functionalized with complementary surface-mobile DNA. We\nassemble colloidal molecules with different coordination number of spheres by\nvarying the size ratio and find that they feature a constrained range of motion\nabove a critical size ratio. Using theory and simulations, we show that the\nparticle shape together with the multivalent bonds create an effective\nfree-energy landscape for the motion of the sphere on the surface of the cube.\nWe quantify the confinement of the spheres on the surface of the cube and the\nprobability to change facet. We find that temperature can be used as an extra\ncontrol parameter to switch in situ between full and constrained flexibility of\nthese colloidal molecules. These flexible colloidal molecules with temperature\nswitching motion range can be used to investigate the effect of directional,\nyet flexible bonds in determining their self-assembly and phase behavior, and\nmay be employed as constructional units in microrobotics and novel smart\nmaterials"
    },
    {
        "anchor": "Folding in lattice models with side chains: The folding kinetics of three-dimensional lattice Go models with side chains\nis studied using two different Monte Carlo move sets. A flexible move set based\non single, double and triple backbone moves is found to be far superior\ncompared to the standard Monte Carlo dynamics. It was found that the folding\ntime grows as a power law with the chain length and the corresponding exponent\n$\\lambda \\approx 3.6$ for Go models. The study shows that the incorporation of\nside chains dramatically slows down folding rates.",
        "positive": "Tuning residual stress, directional memory and aging in soft glassy\n  materials: When glassy materials are rapidly quenched from the liquid to the solid state\nupon flow cessation or cooling, they solidify in an out-of-equilibrium\nconfiguration, retaining the memory of the processing conditions for very long\ntimes. This is the origin of various phenomena, such as residual stresses and\ndirectional memory, which greatly affect their properties. At the same time,\nannealing the mechanical history encoded in disordered materials constitute a\ngreat challenge. Here, we address this problem for the case of colloidal\nglasses made of soft particles densely packed at a high volume fraction, using\nexperiments and particle dynamic simulations. We demonstrate that periodically\ntraining soft particle glasses with a sequence of stress-controlled\noscillations successfully anneals residual stress and directional memory when\nthe stress amplitude corresponds to the yield point. At the microscopic level,\nannealing provides a fine tuning of the local distribution of the stress\ncarried by the particles. Through the simulations, we show that the first\nmoments of this distribution have precise physical meaning: the mean value of\nthe distribution corresponds to the macroscopic stress; the skewness carries\ninformation about directional memory; and the standard deviation is related to\nmechanical aging. The same methodology is successfully applied to silica gels\nwith thixotropic properties, suggesting that it is general and may be extended\nto other classes of disordered materials."
    },
    {
        "anchor": "Collective nonaffine displacements in amorphous materials during\n  large-amplitude oscillatory shear: Using molecular dynamics simulations, we study the transient response of a\nbinary Lennard-Jones glass subjected to periodic shear deformation. The\namorphous solid is modelled as the three-dimensional Kob-Andersen binary\nmixture at a low temperature. The cyclic loading is applied to slowly annealed,\nquiescent samples, which induces irreversible particle rearrangements at large\nstrain amplitudes, leading to stress-strain hysteresis and a drift of the\npotential energy towards higher values. We find that the initial response to\ncyclic shear near the critical strain amplitude involves disconnected clusters\nof atoms with large nonaffine displacements. In contrast, the amplitude of\nshear stress oscillations decreases after a certain number of cycles, which is\naccompanied by the initiation and subsequent growth of a shear band.",
        "positive": "Mechanisms of carrier transport induced by a microswimmer bath: Recently, it was found that a wedgelike microparticle (referred to as\n\"carrier\") which is only allowed to translate but not to rotate exhibits a\ndirected translational motion along the wedge cusp if it is exposed to a bath\nof microswimmers. Here we model this effect in detail by resolving the\nmicroswimmers explicitly using interaction models with different degrees of\nmutual alignment. Using computer simulations we study the impact of these\ninteractions on the transport efficiency of V-shaped carrier. We show that the\ntransport mechanisms itself strongly depends on the degree of alignment\nembodied in the modelling of the individual swimmer dynamics. For weak\nalignment, optimal carrier transport occurs in the turbulent microswimmer state\nand is induced by swirl depletion inside the carrier. For strong aligning\ninteractions, optimal transport occurs already in the dilute regime and is\nmediated by a polar cloud of swimmers in the carrier wake pushing the\nwedge-particle forward. We also demonstrate that the optimal shape of the\ncarrier leading to maximal transport speed depends on the kind of interaction\nmodel used."
    },
    {
        "anchor": "Mechanistic Model for Deformation of Polymer Nanocomposite Melts under\n  Large Amplitude Shear: We report the mechanical response of a model nanocomposite system of\npoly(styrene) (PS)-silica to large-amplitude oscillatory shear deformations.\nNonlinear behavior of PS nanocomposites is discussed with the changes in\nparticle dispersion upon deformation to provide a complete physical picture of\ntheir mechanical properties. The elastic stresses for the particle and polymer\nare resolved by decomposing the total stress into its purely elastic and\nviscous components for composites at different strain levels within a cycle of\ndeformation. We propose a mechanistic model which captures the deformation of\nparticles and polymer networks at small and large strains, respectively. We\nshow, for the first time, that chain stretching in a polymer nanocomposite\nobtained in large amplitude oscillatory deformation is in good agreement with\nthe nonlinear chain deformation theory of polymeric networks.",
        "positive": "Planar equilibria of an elastic rod wrapped around a circular capstan: We present a study on planar equilibria of a terminally loaded elastic rod\nwrapped around a rigid circular capstan. Both frictionless and frictional\ncontact between the rod and the capstan are considered. We identify three cases\nof frictionless contact -- namely where the rod touches the capstan at one\npoint, along a continuous arc, and at two points. We show that, in contrast to\na fully flexible filament, an elastic rod of \\emph{finite length} wrapped\naround a capstan does not require friction to support unequal loads at its two\nends. Furthermore, we classify rod equilibria corresponding to the three\naforementioned cases in a limit where the length of the rod is much larger than\nthe radius of the capstan. In the same limit, we incorporate frictional\ninteraction between the rod and the capstan, and compute limiting equilibria of\nthe rod. Our solution to the frictional case fully generalizes the\n\\emph{classic capstan problem} to include the effects of finite thickness and\nbending elasticity of a flexible filament wrapped around a circular capstan."
    },
    {
        "anchor": "Slow dynamics in an azopolymer molecular layer studied by x-ray photon\n  correlation spectroscopy: We report the results of X-ray photon correlation spectroscopy (XPCS)\nexperiments on Langmuir Blodgett multilayers of a photosensitive azo-polymer.\nTime correlation functions have been measured at different temperatures and\nmomentum transfers (q) and under different illumination conditions (darkness,\nUV or visible). The correlation functions are well described by the\nKohlrausch-Williams-Watts (KWW) form with relaxation times that are\nproportional to q^-1, which in other systems have been explained in terms of\nintermittent rearrangements [L. Cipelletti et al., Phys. Rev. Lett. 84,\n2275-2278 (2000)] or random dipolar interactions within an elastic medium [J.-\nP. Bouchaud and E. Pitard, Eur. Phys. J. E 6, 231-236 (2001)]. The\ncharacteristic relaxation times follow the well known Vogel-Fulcher-Tammann law\ndescribing the temperature dependence of the bulk viscosity of this polymer. UV\nphotoperturbation accelerates the relaxation dynamics, in qualitative agreement\nwith the fluidification effect of UV photo-perturbation previously observed by\nsurface rheometry, and is used to drive the system out of equilibrium.\nTransient dynamics is characterized, by the variance chi of the two-times\ncorrelation functions. A clear peak in chi appears at a well defined time tau_C\nwhich scales with q^-1 and with the ageing time, in a similar fashion as\npreviously reported in colloidal suspensions [O. Dauchot et al., Phys. Rev.\nLett. 95, 265701 (2005)]. From an accurate analysis of the correlation\nfunctions we could demonstrate a temperature dependent cross-over from KWW\ncompressed to simple exponential behaviour, which is modified by the\nfluidification due to the optical pumping of the cis-trans isomerisation of the\nside-chain azobenzene group.",
        "positive": "Multiscale ultrafast laser texturing of marble for reduced surface\n  wetting: The modification of the wetting properties of marble surfaces upon\nmulti-scale texturing induced by ultrafast laser processing (340 fs pulse\nduration, 1030 nm wavelength) has been investigated with the aim of evaluating\nits potential for surface protection. The contact angle (CA) of a water drop\nplaced on the surface was used to assess the wettability of the processed\nareas. Although the surfaces are initially hydrophilic upon laser treatment,\nafter a few days they develop a strong hydrophobic behavior. Marble surfaces\nhave been irradiated with different scan line separations to elucidate the\nrelative roles of multi-scale roughness (nano- and micro-texture) and chemical\nchanges at the surface. The time evolution of the contact angle has been then\nmonitored up to 11 months after treatment. A short and a long-term evolution,\nassociated to the combined effect of multi-scale roughness and the attachment\nof chemical species at the surface over the time, have been observed. XPS and\nATR measurements are consistent with the progressive hydroxylation of the laser\ntreated surfaces although the additional contribution of hydrocarbon adsorbates\nto the wettability evolution cannot be ruled-out. The robustness of the results\nhas been tested by CA measurements after cleaning in different conditions with\nvery positive results."
    },
    {
        "anchor": "Even strong energy polydispersity does not affect the average structure\n  and dynamics of simple liquids: Size-polydisperse liquids have become standard models for avoiding\ncrystallization, thereby enabling studies of supercooled liquids and glasses\nformed, e.g., by colloidal systems. Purely \\textit{energy} polydisperse liquids\nhave been studied much less, but provide an interesting alternative. We here\nstudy numerically the difference in structure and dynamics obtained by\nintroducing these two kinds of polydispersity into systems of particles\ninteracting via the Lennard-Jones and EXP pair potentials. To a very good\napproximation, the average pair structure and dynamics are unchanged even for\nstrong energy polydispersity, while this is not the case for size-polydisperse\nsystems. When the system at extreme energy polydispersity undergoes a\ncontinuous phase separation into lower and higher particle-energy regions whose\nstructure and dynamics are different from the average, the average structure\nand dynamics are still virtually the same as for the monodisperse system. Our\nfindings are consistent with the fact that the distribution of forces on the\nindividual particles do not change when energy polydispersity is introduced,\nwhile they do change in the case of size polydispersity. A theoretical\nexplanation of our findings remains to be found, however.",
        "positive": "Ultrasound transmission through monodisperse 2D microfoams: While the acoustic properties of solid foams have been abundantly\ncharacterized, sound propagation in liquid foams remains poorly understood.\nRecent studies have investigated the transmission of ultrasound through\nthree-dimensional polydisperse liquid foams (Pierre et al., 2013, 2014, 2017).\nHowever, further progress requires to characterize the acoustic response of\nbetter controlled foam structures. In this work, we study experimentally the\ntransmission of ultrasounds through a single layer of monodisperse bubbles\ngenerated by microfluidics techniques. In such a material, we show that the\nsound velocity is only sensitive to the gas phase. Nevertheless, the structure\nof the liquid network has to be taken into account through a transfer parameter\nanalogous to the one in a layer of porous material. Finally, we observe that\nthe attenuation cannot be explained by thermal dissipation alone, but is\ncompatible with viscous dissipation in the gas pores of the monolayer."
    },
    {
        "anchor": "Disentangling Structural Information From Core-level Excitation Spectra: Core-level spectra of liquids can be difficult to interpret due to the\npresence of a range of local environments. We present computational methods for\ninvestigating core-level spectra based on the idea that both local structural\nparameters and the X-ray spectra behave as functions of the local atomic\nconfiguration around the absorbing site. We identify correlations between\nstructural parameters and spectral intensities in defined regions of interest,\nusing the oxygen K-edge excitation spectrum of liquid water as a test case. Our\nresults show that this kind of analysis can find the main structure-spectral\nrelationships of ice, liquid water, and supercritical water.",
        "positive": "Dynamics of a double-stranded DNA segment in a shear flow: We study the dynamics of a double-stranded DNA (dsDNA) segment, as a\nsemiflexible polymer, in a shear flow, the strength of which is customarily\nexpressed in terms of the dimensionless Weissenberg number Wi. Polymer chains\nin shear flows are well-known to undergo tumbling motion. When the chain\nlengths are much smaller than the persistence length, one expects a\n(semiflexible) chain to tumble as a rigid rod. At low Wi, a polymer segment\nshorter than the persistence length does indeed tumble as a rigid rod. However,\nfor higher Wi the chain does not tumble as a rigid rod, even if the polymer\nsegment is shorter than the persistence length. In particular, from time to\ntime the polymer segment may assume a buckled form, a phenomenon commonly known\nas Euler buckling. Using a bead-spring Hamiltonian model for extensible dsDNA\nfragments, we first analyze Euler buckling in terms of the oriented\ndeterministic state (ODS), which is obtained as the steady-state solution of\nthe dynamical equations by turning off the stochastic (thermal) forces at a\nfixed orientation of the chain. The ODS exhibits symmetry breaking at a\ncritical Weissenberg number Wi$_{\\text c}$, analogous to a pitchfork\nbifurcation in dynamical systems. We then follow up the analysis with\nsimulations and demonstrate symmetry breaking in computer experiments,\ncharacterized by a unimodal to bimodal transformation of the probability\ndistribution of the second Rouse mode with increasing Wi. Our simulations\nreveal that shear can cause strong deformation for a chain that is shorter than\nits persistence length, similar to recent experimental observations."
    },
    {
        "anchor": "Recent Advances in the Theory and Simulation of Model Colloidal\n  Microphase Formers: This mini-review synthesizes our understanding of the equilibrium behavior of\nparticle models with short-range attractive and long-range repulsive (SALR)\ninteractions. These models, which can form stable periodic microphases, aim to\nreproduce the essence of colloidal suspensions with competing interactions.\nOrdered structures, however, have yet to be obtained in experiments. In order\nto better understand the hurdles to periodic microphase assembly, marked\ntheoretical and simulation advances have been made over the last few years.\nHere, we present recent progress in the study of microphases in models with\nSALR interactions using liquid-state theory and density-functional theory as\nwell as numerical simulations. Combining these various approaches provides a\ndescription of periodic microphases, and give insights into the rich\nphenomenology of the surrounding disordered regime. Three additional ongoing\nresearch directions in the thermodynamics of models with SALR interactions are\nalso presented.",
        "positive": "Modeling phase behavior for quantifying micro-pervaporation experiments: We present a theoretical model for the evolution of mixture concentrations in\na micro-pervaporation device, similar to those recently presented\nexperimentally. The described device makes use of the pervaporation of water\nthrough a thin PDMS membrane to build up a solute concentration profile inside\na long microfluidic channel. We simplify the evolution of this profile in\nbinary mixtures to a one-dimensional model which comprises two\nconcentration-dependent coefficients. The model then provides a link between\ndirectly accessible experimental observations, such as the widths of dense\nphases or their growth velocity, and the underlying chemical potentials and\nphenomenological coefficients. It shall thus be useful for quantifying the\nthermodynamic and dynamic properties of dilute and dense binary mixtures."
    },
    {
        "anchor": "Quantifying reversibility in a phase-separating lattice gas: an analogy\n  with self-assembly: We present dynamic measurements of a lattice gas during phase separation,\nwhich we use as an analogy for self-assembly of equilibrium ordered structures.\nWe use two approaches to quantify the degree of 'reversibility' of this\nprocess: firstly, we count events in which bonds are made and broken; secondly,\nwe use correlation-response measurements and fluctuation-dissipation ratios to\nprobe reversibility during different time intervals. We show how correlation\nand response functions can be related directly to microscopic (ir)reversibility\nand we discuss time-dependence and observable- dependence of these\nmeasurements, including the role of fast and slow degrees of freedom during\nassembly.",
        "positive": "Comment on Nanoscale Wetting of Crystalline Cellulose: In a recent publication, Trentin et al employed Molecular Dynamics (MD)\nsimulations for the theoretical study of the wetting of the different\npolymorphs of cellulose by water, using the widely employed TIP3P model of\nwater. Here we show that the selection of the particular water model employed\nin the simulations has a critical impact in the results, a point overlooked by\nthe authors. In particular, the TIP3P model of water has an unrealistically low\nvalue of the surface tension which compromises wetting studies made with this\nmodel. Slightly more complex models such as TIP4P2005 correctly reproduce the\nsurface tension of water. As a consequence, the results of MD simulations of\ncellulose wetting using the low-tension TIP3P model show full wetting in\nsituations that the more realistic TIP4P2005 water model predicted the\nformation of a water droplet onto cellulose."
    },
    {
        "anchor": "Suspensions of supracolloidal magnetic polymers: self-assembly\n  properties from computer simulations: We study self-assembly in suspensions of supracolloidal polymer-like\nstructures made of crosslinked magnetic particles. Inspired by self-assembly\nmotifs observed for dipolar hard spheres, we focus on four different topologies\nof the polymer-like structures: linear chains, rings, Y-shaped and X-shaped\npolymers. We show how the presence of the crosslinkers, the number of beads in\nthe polymer and the magnetic interparticle interaction affect the structure of\nthe suspension. It turns out that for the same set of parameters, the rings are\nthe least active in assembling larger structures, whereas the system of Y- and\nespecially X-like magnetic polymers tend to form very large loose aggregates.",
        "positive": "Effect of Persistent Noise on the XY Model and Two-Dimensional Crystals: Two-dimensional (2D) crystals made of active particles were shown recently to\nbe able to experience extremely large spontaneous deformations without melting.\nThe root of this phenomenon was argued to lie in the time-persistence of the\norientation of the intrinsic axes of particles. Here, we pursue this idea and\nconsider passive systems subjected to time-persistent external perturbations.\nWe first study a 2D XY model subjected to time-correlated noise and find that\nit can remain quasi-ordered in spite of correlations decaying much faster than\nallowed in equilibrium. We then study a simple model of a passive 2D crystal\nimmersed in a bath of active particles, and show that it can sustain large\ndeformations without melting."
    },
    {
        "anchor": "Theory of Banana Liquid Crystal Phases and Phase Transitions: We study phases and phase transitions that can take place in the newly\ndiscovered banana (bow-shaped or bent-core) liquid crystal molecules. We show\nthat to completely characterize phases exhibited by such bent-core molecules a\nthird-rank tensor $T^{ijk}$ order parameter is necessary in addition to the\nvector and the nematic (second-rank) tensor order parameters. We present an\nexhaustive list of possible liquid phases, characterizing them by their\nspace-symmetry group and order parameters, and catalog the universality classes\nof the corresponding phase transitions that we expect to take place in such\nbent-core molecular liquid crystals. In addition to the conventional\nliquid-crystal phases such as the nematic phase, we predict the existence of\nnovel liquid phases, including the spontaneously chiral nematic $(N_T + 2)^*$\nand chiral polar $(V_T + 2)^*$ phases, the orientationally-ordered but\noptically isotropic tetrahedratic $T$ phase, and a novel nematic $N_T$ phase\nwith $D_{2d}$ symmetry that is neither uniaxial nor biaxial. Interestingly, the\nIsotropic-Tetrahedratic transition is {\\em continuous} in mean-field theory,\nbut is likely driven first-order by thermal fluctuations. We conclude with a\ndiscussion of smectic analogs of these phases and their experimental\nsignatures.",
        "positive": "Inferring the stability of concentrated emulsions from droplet\n  configuration information: When droplets are tightly packed in a 2D microchannel, coalescence of a pair\nof droplets can trigger an avalanche of coalescence events that propagate\nthrough the entire emulsion. This propagation is found to be stochastic, i.e.\nevery coalescence event does not necessarily trigger another. To study how the\nlocal probabilistic propagation affects the dynamics of the avalanche, as a\nwhole, a stochastic agent based model is used. Taking as input, i) how the\ndroplets are packed (configuration) and ii) a measure of local probabilistic\npropagation (experimentally derived; function of fluid and other system\nparameters), the model predicts the expected size distribution of avalanches.\nIn this article, we investigate how droplet configuration affects the avalanche\ndynamics. We find the mean size of these avalanches to depend non-trivially on\nhow droplets are packed together. Large variations in the avalanche dynamics\nare observed when droplet packing are different, even when the other system\nproperties (number of droplets, fluid properties, channel geometry, etc.) are\nkept constant. Bidisperse emulsions show less variation in the dynamics and\nthey are surprisingly more stable than monodisperse emulsions. To get a\nsystems-level understanding of how a given droplet-configuration either\nfacilitates or impedes the propagation of an avalanche, we employ a\ngraph-theoretic analysis, where emulsions are expressed as graphs. We find that\nthe properties of the underlying graph, namely the mean degree and the\nalgebraic connectivity, are well correlated with the observed avalanche\ndynamics. We exploit this dependence to derive a data-based model that predicts\nthe expected avalanche sizes from the properties of the graph."
    },
    {
        "anchor": "A change in stripes for cholesteric shells via anchoring in moderation: Chirality, ubiquitous in complex biological systems, can be controlled and\nquantified in synthetic materials such as cholesteric liquid crystal (CLC)\nsystems. In this work, we study spherical shells of CLC under weak anchoring\nconditions. We induce anchoring transitions at the inner and outer boundaries\nusing two independent methods: by changing the surfactant concentration or by\nraising the temperature close to the clearing point. The shell confinement\nleads to new states and associated surface structures: a state where large\nstripes on the shell can be filled with smaller, perpendicular sub-stripes, and\na focal conic domain (FCD) state, where thin stripes wrap into at least two,\ntopologically required, double spirals. Focusing on the latter state, we use a\nLandau-de Gennes model of the CLC to simulate its detailed configurations as a\nfunction of anchoring strength. By abruptly changing the topological\nconstraints on the shell, we are able to study the interconversion between\ndirector defects and pitch defects, a phenomenon usually restricted by the\ncomplexity of the cholesteric phase. This work extends the knowledge of\ncholesteric patterns, structures that not only have potential for use as\nintricate, self-assembly blueprints but are pervasive in biological systems.",
        "positive": "Comment on \"Dynamics in an oil-continuous droplet microemulsion as seen\n  by quasielastic scattering techniques\" by T. Hellweg et al: It is shown that the interpretation of quasielastic scattering experiments on\ndroplet microemulsions in the paper by T. Hellweg et al., Phys. Chem. Chem.\nPhys., 2000, 2, 5168, contains serious shortcomings and should be revised."
    },
    {
        "anchor": "Equation of state of a Fermi gas in the BEC-BCS crossover: a quantum\n  Monte Carlo study: We calculate the equation of state of a two-component Fermi gas with\nattractive short-range interspecies interactions using the fixed-node diffusion\nMonte Carlo method. The interaction strength is varied over a wide range by\ntuning the value $a$ of the s-wave scattering length of the two-body potential.\nFor $a>0$ and $a$ smaller than the inverse Fermi wavevector our results show a\nmolecular regime with repulsive interactions well described by the dimer-dimer\nscattering length $a_m=0.6 a$. The pair correlation functions of parallel and\nopposite spins are also discussed as a function of the interaction strength.",
        "positive": "Statistical physics of isotropic-genesis nematic elastomers: I.\n  Structure and correlations at high temperatures: Isotropic-genesis nematic elastomers (IGNEs) are liquid crystalline polymers\n(LCPs) that have been randomly, permanently cross-linked in the\nhigh-temperature state so as to form an equilibrium random solid. Thus, instead\nof being free to diffuse throughout the entire volume, as they would be in the\nliquid state, the constituent LCPs in an IGNE are mobile only over a finite\nlength-scale controlled by the density of cross-links. We address the effects\nthat such network-induced localization have on the liquid-crystalline\ncharacteristics of an IGNE, as probed via measurements made at high\ntemperatures. In contrast with the case of uncross-linked LCPs, for IGNEs these\ncharacteristics are determined not only by thermal fluctuations but also by the\nquenched disorder associated with the cross-link constraints. To study IGNEs,\nwe consider a microscopic model of dimer nematogens in which the dimers\ninteract via orientation-dependent excluded volume forces. The dimers are,\nfurthermore, randomly, permanently cross-linked via short Hookean springs, the\nstatistics of which we model by means of a Deam-Edwards type of distribution.\nWe show that at length-scales larger than the size of the nematogens this\napproach leads to a recently proposed phenomenological Landau theory of IGNEs\n[Lu et al., Phys. Rev. Lett. 108, 257803 (2012)], and hence predicts a regime\nof short-ranged oscillatory spatial correlations in the nematic alignment, of\nboth thermal and glassy types. In addition, we consider two alternative\nmicroscopic models of IGNEs: (i) a wormlike chain model of IGNEs that are\nformed via the cross-linking of side-chain LCPs; and (ii) a jointed chain model\nof IGNEs that are formed via the cross-linking of main-chain LCPs. At large\nlength-scales, both of these models give rise to liquid-crystalline\ncharacteristics that are qualitatively in line with those predicted by the\ndimer-and-springs model."
    },
    {
        "anchor": "Nonequilibrium Theory of Epigenomic Microphase Separation in the Cell\n  Nucleus: Understanding the spatial organisation of the genome in the cell nucleus is\none of the current grand challenges in biophysics. Certain biochemical -- or\nepigenetic -- marks that are deposited along the genome are thought to play an\nimportant, yet poorly understood, role in determining genome organisation and\ncell identity. The physical principles underlying the interplay between\nepigenetic dynamics and genome folding remain elusive. Here we propose and\nstudy a theory that assumes a coupling between epigenetic mark and genome\ndensities, and which can be applied at the scale of the whole nucleus. We show\nthat equilibrium models are not compatible with experiments and a qualitative\nagreement is recovered by accounting for non-equilibrium processes which can\nstabilise microphase separated epigenomic domains. We finally discuss the\npotential biophysical origin of these terms.",
        "positive": "Molecular Dynamics Simulation Study of Nonconcatenated Ring Polymers in\n  a Melt: II. Dynamics: Molecular dynamics simulations were conducted to investigate the dynamic\nproperties of melts of nonconcatenated ring polymers and compared to melts of\nlinear polymers. The longest rings were composed of N=1600 monomers per chain\nwhich corresponds to roughly 57 entanglement lengths for comparable linear\npolymers. The ring melts were found to diffuse faster than their linear\ncounterparts, with the self-diffusion coefficient for both architectures\nscaling as approximately N to the -2.4 power for large N. The mean-square\ndisplacement of the center-of-mass of the rings follows a sub-diffusive\nbehavior for times and distances beyond the mean-square gyration radius,\nneither compatible with the Rouse nor the reptation model. The rings relax\nstress much faster than linear polymers and the zero-shear viscosity was found\nto vary as approximately N to the 1.4 power which is much weaker than the N to\nthe 3.4 power of linear chains, not matching any commonly known model for\npolymer dynamics when compared to the observed mean-square displacements. These\nfindings are discussed in view of the conformational properties of the rings\npresented in the preceding paper (DOI: 10.1063/1.3587137)."
    },
    {
        "anchor": "Telechelic star polymers as self-assembling units from the molecular to\n  the macroscopic scaleBarbara Capone: By means of multiscale molecular simulations, we show that telechelic-star\npolymers are a simple, robust and tunable system, which hierarchically\nself-assembles first into soft-patchy particles and then into targeted\ncrystalline structures. The self-aggregating patchy behavior can be fully\ncontrolled by the number of arms per star and by the fraction of attractive\nmonomeric units at the free ends of the arms. Such self-assembled soft-patchy\nparticles while forming, upon augmenting density, gel-like percolating networks\nand stable ordered structures, preserve properties as particle size, number and\narrangement of patches per particle. In particular, we demonstrate that the\nflexibility inherent in the soft-patchy particles brings forward a novel\nmechanism that leads to the stabilisation of diamond and simple cubic crystals\nover a wide range of densities, and for molecular sizes ranging from about 10\nnm up to the micrometer scale.",
        "positive": "The critical state of granular media: Convergence, stationarity, and\n  disorder: Discrete-element simulations are used to monitor several micro-scale\ncharacteristics within a granular material, demonstrating their convergence\nduring loading toward the critical state, their stationarity at the critical\nstate, and the evolution of their disorder toward the critical state.\nConvergence, stationarity and disorder are studied in the context of the\nShannon entropy and two forms of Kullback-Leibler relative entropy. Probability\ndistributions of 20 aspects of micro-scale configuration, force and movement\nare computed for three topological objects: particles, voids and contacts. The\nprobability distributions of these aspects are determined at numerous stages\nduring quasi-static biaxial compression and unloading. Not only do stress and\ndensity converge to the critical state, but convergence and stationarity are\nmanifested in all of the micro-scale aspects. The statistical disorder\n(entropy) of micro-scale movements and strains generally increases during\nloading until the critical state is reached. When the loading direction is\nreversed, order is briefly restored, but continued loading induces greater\ndisorder in movements and strains until the critical state is reached again."
    },
    {
        "anchor": "Electroadhesion for soft adhesive pads and robotics: theory and\n  numerical results: Soft adhesive pads are needed for many robotics applications, and one\napproach is based on electroadhesion. Here we present a general analytic model\nand numerical results for electroadhesion for soft solids with arbitrary\ntime-dependent applied voltage, and arbitrary dielectric response of the\nsolids, and including surface roughness. We consider the simplest\ncoplanar-plate-capacitor model with a periodic array of conducting strips\nlocated close to the surface of the adhesive pad, and discuss the optimum\ngeometrical arrangement to obtain the maximal electroadhesion force. For\nsurfaces with roughness the (non-contact) gap between the solids will strongly\ninfluence the electroadhesion, and we show how the electroadhesion force can be\ncalculated using a contact mechanics theory for elastic solids. The theory and\nmodels we present can be used to optimize the design of adhesive pads for\nrobotics application.",
        "positive": "PDF's Of The Burgers Equation On The Semiline With Fluctuating Flux At\n  The Origin: We derive the asymptotic behaviour of the one point probability density for\nthe inhomogeneous shock slopes in the turbulent regime, when a Gaussian\nfluctuating flux at origin derives the system. We also calculate the time\ndependence of the $x_{f}$ beyond which there won't exists any velocity shocks\nas $ x_{f}\\cong t^{3/4}{(log{t})}^{1\\4}$. We argue that the stationary state of\nthe problem would be equivalent with the long time limit of the diffusion\nequation with arandom source at origin."
    },
    {
        "anchor": "Occurrence of connected clusters in motility-induced phase-separated\n  states of persistent active particles at zero temperature: To study the interplay of jamming, cluster formation, and motility-induced\nphase separation in the zero temperature limit in two dimensions, we consider a\nsimple model system consisting of a bidisperse mixture of disks that are only\nsubject to a repulsion force in case of overlaps and an active force. The\norientation of the disks is chosen randomly in the beginning and does not\nchange anytime during the simulation thus corresponding to an infinite\npersistence length. Simulations with our model system reveal that jammed\nclusters of particles occur in the dense phase of a phase-separated state in\ncase of intermediate values of the ratio of active to repulsive force. However,\nfor smaller activities there are only a few overlaps between the particles in\nthe dense phase and the coexistence region ends at a packing fraction below the\nonset of jamming. Finally, for large activities small clusters corresponding to\nsmall patches of the dense phase are found that are unstable due to the\nactivity. Our findings on how jamming and phase separation are related are\nrelevant to many active particle systems whose zero temperature and long\npersistence limits correspond to our model system.",
        "positive": "A frictional Cosserat model for the slow shearing of granular materials: A rigid-plastic Cosserat model for slow frictional flow of granular\nmaterials, proposed by us in an earlier paper, has been used to analyze plane\nand cylindrical Couette flow. In this model, the hydrodynamic fields of a\nclassical continuum are supplemented by the couple stress and the intrinsic\nangular velocity fields. The balance of angular momentum, which is satisfied\nimplicitly in a classical continuum, must be enforced in a Cosserat continuum.\nAs a result, the stress tensor could be asymmetric, and the angular velocity of\na material point may differ from half the local vorticity. An important\nconsequence of treating the granular medium as a Cosserat continuum is that it\nincorporates a material length scale in the model, which is absent in\nfrictional models based on a classical continuum. Further, the Cosserat model\nallows determination of the velocity fields uniquely in viscometric flows, in\ncontrast to classical frictional models. Experiments on viscometric flows of\ndense, slowly deforming granular materials indicate that shear is confined to a\nnarrow region, usually a few grain diameters thick, while the remaining\nmaterial is largely undeformed. This feature is captured by the present model,\nand the velocity profile predicted for cylindrical Couette flow is in good\nagreement with reported data. When the walls of the Couette cell are smoother\nthan the granular material, the model predicts that the shear layer thickness\nis independent of the Couette gap $H$ when the latter is large compared to the\ngrain diameter $d_p$. When the walls are of the same roughness as the granular\nmaterial, the model predicts that the shear layer thickness varies as\n$(H/d_p)^{1/3}$ in the limit $(H/d_p) \\gg 1$, for plane shear under gravity and\ncylindrical Couette flow."
    },
    {
        "anchor": "Linking high and low temperature plasticity in bulk metallic glasses:\n  thermal activation, extreme value statistics and kinetic freezing: At temperatures well below their glass transition, the deformation properties\nof bulk metallic glasses are characterised by a sharp transition from\nelasticity to plasticity, a reproducible yield stress, and an approximately\nlinear decrease of this stress with increasing temperature. In the present work\nit shown that when the well known properties of the under-cooled liquid regime,\nin terms of the underlying potential energy landscape, are assumed to be also\nvalid at low temperature, a simple thermal activation model is able to\nreproduce the observed onset of macro-scopic yield. At these temperatures, the\nthermal accessibility of the complex potential energy landscape is drastically\nreduced, and the statistics of extreme value and the phenomenon of kinetic\nfreezing become important, affecting the spatial heterogeneity of the\nirreversible structural transitions mediating the elastic-to-plastic\ntransition. As the temperature increases and approaches the glass transition\ntemperature, the theory is able to smoothly transit to the high temperature\ndeformation regime where plasticity is known to be well described by thermally\nactivated viscoplastic models.",
        "positive": "Ground-State Shapes and Structures of Colloidal Domains: In charged colloidal suspensions, the competition between square-well\nattraction and long-range Yukawa repulsion leads to various stable domains and\nWigner supercrystals. Using a continuum model and symmetry arguments, a phase\ndiagram of spheres, cylinders, and lamellae is obtained as a function of two\ncontrol parameters, the volume fraction and the ratio between the surface\ntension and repulsion. Above a critical value of the ratio, the microphase\ncannot be supported by the Yukawa repulsion and macroscopic phase separation\noccurs. This finding quantitatively explains the lack of pattern formation in\nsimple liquids because of the small hard sphere diameter in comparison with the\nsize of macromolecules. The phase diagram also predicts microphase separation\nat zero value of the ratio, suggesting the possibility of self-assembly in\nrepulsive systems."
    },
    {
        "anchor": "Extended Wertheim theory predicts the anomalous chain length\n  distributions of divalent patchy particles under extreme confinement: Colloidal patchy particles with divalent attractive interaction can\nself-assemble into linear polymer chains. Their equilibrium properties in 2D\nand 3D are well described by Wertheim's thermodynamic perturbation theory which\npredicts a well-defined exponentially decaying equilibrium chain length\ndistribution. In experimental realizations, due to gravity, particles sediment\nto the bottom of the suspension forming a monolayer of particles with a\ngravitational height smaller than the particle diameter. In accordance with\nexperiments, an anomalously high monomer concentration is observed in\nsimulations which is not well understood. To account for this observation, we\ninterpret the polymerization as taking place in a highly confined quasi-2D\nplane and extend the Wertheim thermodynamic perturbation theory by defining\naddition reactions constants as functions of the chain length. We derive the\ntheory, test it on simple square well potentials, and apply it to the\nexperimental case of synthetic colloidal patchy particles immersed in a binary\nliquid mixture that are described by an accurate effective critical Casimir\npatchy particle potential. The important interaction parameters entering the\ntheory are explicitly computed using the integral method in combination with\nMonte Carlo sampling. Without any adjustable parameter, the predictions of the\nchain length distribution are in excellent agreement with explicit simulations\nof self-assembling particles. We discuss generality of the approach, and its\napplication range.",
        "positive": "Effect of aspect ratio on transverse diffusive broadening: A lattice\n  Boltzmann study: We study scaling laws characterizing the inter-diffusive zone between two\nmiscible fluids flowing side by side in a Y-shape laminar micromixer using the\nlattice Boltzmann method. The lattice Boltzmann method solves the coupled 3D\nhydrodynamics and mass transfer equations and incorporates intrinsic features\nof 3D flows related to this problem. We observe the different power law regimes\noccurring at the center of the channel and close to the top/bottom wall. The\nextent of the inter-diffusive zone scales as square root of the axial distance\nat the center of the channel. At the top/bottom wall, we find an exponent 1/3\nat early stages of mixing as observed in the experiments of Ismagilov and\ncoworkers [Appl. Phys. Lett. 76, 2376 (2000)]. At a larger distance from the\nentrance, the scaling exponent close to the walls changes to 1/2 [J.-B. Salmon\net al J. Appl. Phys. 101, 074902 (2007)]. Here, we focus on the effect of\nfinite aspect ratio on diffusive broadening. Interestingly, we find the same\nscaling laws regardless of the channel's aspect ratio. However,the point at\nwhich the exponent 1/3 characterizing the broadening at the top/bottom wall\nreverts to the normal diffusive behavior downstream strongly depends on the\naspect ratio. We propose an interpretation of this observation in terms of\nshear rate at the side walls. A criterion for the range of aspect ratios with\nnon-negligible effect on diffusive broadening is also provided."
    },
    {
        "anchor": "Branched Polymers with Excluded Volume Effects/ Relationship between\n  Polymer Dimensions and Generation Number: We discuss the extension of the empirical equation: $\\left\\langle\ns_{N}^{2}\\right\\rangle_{0}\\propto g\\,l^{2}$, where the subscript 0 denotes the\nideal value with no excluded volume and $g$ the generation number from the root\nto the youngest (outermost) generation. By analogy with the linear chain\nproblem, we introduce the assumption that the scaling relation, $\\left\\langle\ns_{N}^{2}\\right\\rangle_{0}\\propto g^{2\\lambda}\\,l^{2}$, exists for arbitrary\npolymeric architectures, where $\\lambda$ is an exponent for the backbone\nstructure. Then, making use of the relationship between $g$ and $N$ (monomer\nnumber), we can deduce the exponent, $\\nu$, for polymers with various\narchitectures. The theory of the excluded volume effects impose the severe\nrestriction on the quantities: $\\nu_{0}$, $\\nu$, and $\\lambda$; for instance,\nthe inequality, $\\nu_{0}\\ge\\frac{1}{d+1}$, must be satisfied for isolated\npolymers in good solvents. An intriguing question is whether or not there\nexists an actual molecule that violates this inequality. We take up two\nexamples having $\\nu_{0}=1/4$ for $d=2$ and $\\nu_{0}=1/6$ for $d=3$, and\ndiscuss this question.",
        "positive": "Cooperative O-H$\\cdots\u03c0$ and C-H$\\cdots$O Hydrogen Bonding in\n  Benzene-Methanol Solution: Strong Structures from Weak Interactions: Weak hydrogen bonds, such as O-H$\\cdots\\pi$ and C-H$\\cdots$O, are pivotal in\na wide range of important natural and industrial processes including\nbiochemical assembly, molecular recognition, and chemical selectivity. In this\nstudy we use neutron diffraction in conjunction with comprehensive H/D isotopic\nsubstitution to obtain a detailed spatial and orientational picture of the\nstructure in benzene-methanol solution. This system provides us with a\nprototypical situation where the aromatic ring can act as an hydrogen bond\nacceptor (via the $\\pi$ electron density) and/or a hydrogen bond donor (via the\nCH groups), with the potential for cooperative effects. Our analysis places\nbenzene at the centre of our frame-of-reference, and reveals for the first time\nthat in solution the O-H$\\cdots\\pi$ interaction is highly localised and\ndirectional, the hydrogen atom being located directly above/below the ring\ncentroid at a distance of 2.30 {\\AA} and with the hydroxyl bond axis normal to\nthe aromatic plane. The tendency of methanol to form chain and cyclic motifs in\nthe bulk liquid is manifest in a highly templated, symmetrical equatorial\nsolvation structure; the methanol molecules surround the benzene so that the\nO-H bonds are coplanar with the aromatic ring while the oxygens interact with\nC-H groups through simultaneous bifurcated hydrogen bonds. By contrast,\nC-H$\\cdots\\pi$ interactions are relegated to the role of more distant\nspectators. The experimentally observed solvation therefore demonstrates that\nweak hydrogen bonding can give rise to strongly-ordered cooperative structural\nmotifs also in the liquid phase."
    },
    {
        "anchor": "Retarded and nonretarded van der Waals interactions between a cluster\n  and a second cluster or a conducting surface: In some respects, a cluster consisting of many atoms may be regarded as a\nsingle large atom. Knowing the dielectric properties of such a cluster permits\none to evaluate the form of the van der Waals (dispersion) interactions between\ntwo clusters or between one cluster and a surface. In this paper, we derive\nthese interactions in two extreme opposite regimes of separation: fully\nretarded and nonretarded. In the fully retarded regime (very large separation),\nthe magnitude of the interaction is determined by just the static\npolarizability of the cluster(s). In the nonretarded regime (small separation),\nwe employ a single resonant frequency model of thecluster polarizability to\nderive expressions for the interactions' coefficients. Numerical examples are\npresented to demonstrate that many-body screening of these interactions can be\nsignificant. The results represent the corrections to the commonly used\napproximation of pairwise additivity of interatomic interactions.",
        "positive": "Orientation of topological defects in 2D nematic liquid crystals: Topological defects are an essential part of the structure and dynamics of\nall liquid crystals, and they are particularly important in experiments and\nsimulations on active liquid crystals. In a recent paper, Vromans and Giomi\n[Soft Matter, 2016, 12, 6490] pointed out that topological defects are not\npoint-like objects but actually have orientational properties, which strongly\naffect the energetics and motion of the defects. That paper developed a\nmathematical formalism which describes the orientational properties as vectors.\nHere, we agree with the basic concept of defect orientation, but we suggest an\nalternative mathematical formalism. We represent the defect orientation by a\ntensor, with a rank that depends on the topological charge: rank 1 for a charge\nof +1/2, rank 3 for a charge of -1/2. Using this tensor formalism, we calculate\nthe orientation-dependent interaction between defects, and we present numerical\nsimulations of defect motion."
    },
    {
        "anchor": "Molecular formations in ultracold mixtures of interacting and\n  noninteracting atomic gases: Atom-molecule equilibrium for molecular formation processes is discussed for\nboson-fermion, fermion-fermion, and boson-boson mixtures of ultracold atomic\ngases in the framework of quasichemical equilibrium theory. After presentation\nof the general formulation, zero-temperature phase diagrams of the\natom-molecule equilibrium states are calculated analytically; molecular, mixed,\nand dissociated phases are shown to appear for the change of the binding energy\nof the molecules. The temperature dependences of the atom or molecule densities\nare calculated numerically, and finite-temperature phase structures are\nobtained of the atom-molecule equilibrium in the mixtures. The transition\ntemperatures of the atom or molecule Bose-Einstein condensations are also\nevaluated from these results. Quantum-statistical deviations of the law of mass\naction in atom-molecule equilibrium, which should be satisfied in mixtures of\nclassical Maxwell-Boltzmann gases, are calculated, and the difference in the\ndifferent types of quantum-statistical effects is clarified. Mean-field\ncalculations with interparticle interactions (atom-atom, atom-molecule, and\nmolecule-molecule) are formulated, where interaction effects are found to give\nthe linear density-dependent term in the effective molecular binding energies.\nThis method is applied to calculations of zero-temperature phase diagrams,\nwhere new phases with coexisting local-equilibrium states are shown to appear\nin the case of strongly repulsive interactions.",
        "positive": "Granular discharge rate for submerged hoppers: The discharge of spherical grains from a hole in the bottom of a right\ncircular cylinder is measured with the entire system underwater. We find that\nthe discharge rate depends on filling height, in contrast to the well-known\ncase of dry non-cohesive grains. It is further surprising that the rate\nincreases up to about twenty five percent, as the hopper empties and the\ngranular pressure head decreases. For deep filling, where the discharge rate is\nconstant, we measure the behavior as a function of both grain and hole\ndiameters. The discharge rate scale is set by the product of hole area and the\nterminal falling speed of isolated grains. But there is a small-hole cutoff of\nabout two and half grain diameters, which is larger than the analogous cutoff\nin the Beverloo equation for dry grains."
    },
    {
        "anchor": "Magnetically tunable electrokinetic instability and structuring of\n  non-equilibrium nanoparticle gradients: Inspired by emergent behaviors of living matter, there is increasing interest\nin developing approaches to create dynamic patterns and structures in synthetic\nmaterials with controllable complexity to enable functionalities that are not\npossible in thermodynamic equilibrium. Here we show that electrophoretically\ndriven and maintained non-equilibrium gradients of magnetic nanoparticles in\nnon-polar solvent can undergo electrokinetic instabilities (EKI), leading to\nvarious electrically controllable spatiotemporally patterned states. These\nelectrokinetic instabilities and patterns can be tuned with a magnetic field\nvia magnetostatic energy reduction mechanism to both increase and decrease the\npattern complexity. We reflect the experimental observations on the theoretical\nelectrokinetic and magnetostatic arguments. We further show that small amounts\nof polar water in the otherwise non-polar system are critical enablers for the\nelectrophoretic mobility of the nanoparticles. Since functionalities of\nmagnetic nanoparticles are widely tunable, we foresee that the combination of\ndissipative electrokinetic driving and magnetic energy reduction can lead to\nnovel functional dissipative materials.",
        "positive": "Topological defects in multi-layered swarming bacteria: Topological defects, which are singular points in a director field, play a\nmajor role in shaping active systems. Here, we experimentally study topological\ndefects and the flow patterns around them, that are formed during the highly\nrapid dynamics of swarming bacteria. The results are compared to the\npredictions of two-dimensional active nematics. We show that, even though some\nof the assumptions underlying the theory do not hold, the swarm dynamics is in\nagreement with two-dimensional nematic theory. In particular, we look into the\nmulti-layered structure of the swarm, which is an important feature of real,\nnatural colonies, and find a strong coupling between layers. Our results\nsuggest that the defect-charge density is hyperuniform, i.e., that long range\ndensity-fluctuations are suppressed."
    },
    {
        "anchor": "The stress field and energy of screw dislocation in smectic-A liquid\n  crystals and on the mistakes of the classical solution: The mistakes of the classical solution of screw dislocations in smectic-A\nliquid crystals are pointed out. This reveals a serious problem of the\nwell-known theory, which may be named de Gennes-Kleman-Pershan paradox, for\nmany decades in the scientific community of liquid crystal study. The correct\nsolution is given in this letter in terms of simplest, elementary and\nstraightforward solution method. Furthermore, the stress filed and energy of\ndislocation are discussed in detail. The present article gives a corrected\nstress field and dislocation energy as well.",
        "positive": "Elastocapillary driven assembly of particles at free-standing smectic-A\n  films: Colloidal particles at complex fluid interfaces and within films assemble to\nform ordered structures with high degrees of symmetry via interactions that\ninclude capillarity, elasticity, and other fields like electrostatic charge.\nHere we study microparticle interactions within free-standing smectic-A films,\nin which the elasticity arising from the director field distortion and\ncapillary interactions arising from interface deformation compete to direct the\nassembly of motile particles. New colloidal assemblies and patterns, ranging\nfrom 1D chains to 2D aggregates, sensitive to the initial wetting conditions of\nparticles at the smectic film, are reported. This work paves the way to\nexploiting LC interfaces as a means to direct spontaneously formed,\nreconfigurable, and optically active materials."
    },
    {
        "anchor": "Siloxane molecules: Nonlinear elastic behavior and fracture\n  characteristics: Fracture phenomena in soft materials span multiple length- and timescales.\nThis poses a major challenge in computational modeling and predictive materials\ndesign. To pass quantitatively from molecular- to continuum scales, a precise\nrepresentation of the material response at the molecular level is vital. Here,\nwe derive the nonlinear elastic response and fracture characteristics of\nindividual siloxane molecules using molecular dynamics (MD) studies. For short\nchains, we find deviations from classical scalings for both the effective\nstiffness and mean chain rupture times. A simple model of a non-uniform chain\nof Kuhn segments captures the observed effect and agrees well with MD data. We\nfind that the dominating fracture mechanism depends on the applied force scale\nin a non-monotonic fashion. This analysis suggests that common\npolydimethylsiloxane (PDMS) networks fail at crosslinking points. Our results\ncan be readily lumped into coarse-grained models. Although focusing on PDMS as\na model system, our study presents a general procedure to pass beyond the\nwindow of accessible rupture times in MD studies employing mean first passage\ntime theory, which can be exploited for arbitrary molecular systems.",
        "positive": "Diverse densest ternary sphere packings: The exploration of the densest sphere packings is a fundamental problem in\nmathematics and a wide variety of sciences including materials science. We\npresent our exhaustive computational exploration of the densest ternary sphere\npackings (DTSPs) for 451 radius ratios and 436 compositions on top of our\nprevious study [Koshoji and Ozaki, Phys. Rev. E 104, 024101 (2021)]. The\nunbiased exploration discovers diverse 22 putative DTSPs, and thereby 60\nputative DTSPs are identified in total including the 38 DTSPs discussed by the\nprevious study. Some of the discovered DTSPs are well-ordered, for example, the\nmedium spheres in the (9-7-3) structure are placed in a straight line with\ncomprising the unit cell, and the DTSP has the $Pm \\bar{3}m$ symmetry if the\nstructural distortion is corrected. At a considerable number of radius ratios,\nthe highest packing fractions are achieved by the phase separations consisting\nof only the FCC and/or the putative densest binary sphere packings (DBSPs) for\nall compositions, and the tendency is getting evident as the small and medium\nspheres are getting larger. The result seems to indicate directly that the\nlocal structures in the DBSPs may be denser than those consisting of three\nkinds of spheres. However, the unit cell of undiscovered DTSPs might only be\nmuch larger than in this study due to the complexity of the ternary local\nstructures. Finally, we discuss the correspondence of the DTSPs with real\ncrystals based on the space group. Our study suggests that the diverse\nstructures of DTSPs can be effectively used as structural prototypes for\nsearching ternary, quaternary, and quinary crystal structures."
    },
    {
        "anchor": "Charge-induced phase separation in lipid membranes: The phase separation in lipid bilayers that include negatively charged lipids\nis examined experimentally. We observed phase-separated structures and\ndetermined the membrane miscibility temperatures in several binary and ternary\nlipid mixtures of unsaturated neutral lipid, dioleoylphosphatidylcholine\n(DOPC), saturated neutral lipid, dipalmitoylphosphatidylcholine (DPPC),\nunsaturated charged lipid, dioleoylphosphatidylglycerol\n(DOPG$^{\\scriptsize{(-)}}$), saturated charged lipid,\ndipalmitoylphosphatidylglycerol (DPPG$^{\\scriptsize{(-)}}$), and cholesterol.\nIn binary mixtures of saturated and unsaturated charged lipids, the combination\nof the charged head with the saturation of hydrocarbon tail is a dominant\nfactor for the stability of membrane phase separation.\nDPPG$^{\\scriptsize{(-)}}$ enhances phase separation, while\nDOPG$^{\\scriptsize{(-)}}$ suppresses it. Furthermore, the addition of\nDPPG$^{\\scriptsize{(-)}}$ to a binary mixture of DPPC/cholesterol induces phase\nseparation between DPPG$^{\\scriptsize{(-)}}$-rich and cholesterol-rich phases.\nThis indicates that cholesterol localization depends strongly on the electric\ncharge on the hydrophilic head group rather than on the ordering of the\nhydrocarbon tails. Finally, when DPPG$^{\\scriptsize{(-)}}$ was added to a\nneutral ternary system of DOPC/DPPC/Cholesterol (a conventional model of\nmembrane rafts), a three-phase coexistence was produced. We conclude by\ndiscussing some qualitative features of the phase behaviour in charged\nmembranes using a free energy approach.",
        "positive": "Non-affine fiber reorientation in finite inelasticity: This paper introduces a model for the mechanical response of anisotropic soft\nmaterials undergoing large inelastic deformations. The composite is constituted\nby a soft isotropic matrix reinforced with stiff fibres, that can evolve\nindependently from each other. The constitutive equations are provided in terms\nof the free energy density and the dissipation density which are both required\nto be thermodynamically consistent and structurally frame-indifferent, i.e.,\nthey must be independent of a rotation overimposed on the natural state. This\nis in contrast to many of the currently used inelastic models for soft\nfiber-reinforced materials which do not deal with the lack of uniqueness of the\nnatural state. A constraint between the inelastic spin of the matrix and the\nrotation spin of the fibre is introduced to fully determined the natural state.\nThe resulting flow rules of the inelastic processes incorporate some typical\nscenarios including viscoelasticity and growth."
    },
    {
        "anchor": "Biaxial layering transition of hard rod-like particles in narrow\n  slit-like pores: The phase behavior of hard rectangular rods with length L and diameter D is\nstudied in a narrow slit-like pore using the Parsons-Lee density functional\ntheory. Using the restricted orientation approximation, we find strong\nadsorption at the walls with planar ordering, second order uniaxial-biaxial\nordering transitions and first order layering transitions. The layering\ntransition takes place between two fluids having n and n+1 layers, where the\nlayer spacing is in the order of D. In the case of weak shape anisotropy\n(L/D=3), the coexisting fluids can be either uniaxial or biaxial, while both\nphases are found to be biaxial for L/D=6 and L/D=9. Interestingly, even two or\nmore layering transitions can be observed with increasing density at a given\nshape anisotropy and pore width.",
        "positive": "Autonomously Probing Viscoelasticity in Disordered Suspensions: Recent experiments show a strong rotational-diffusion enhancement for\nself-propelled microrheological probes in colloidal glasses. Here, we provide\nmicroscopic understanding using simulations with a frictional probe-medium\ncoupling that converts active translation into rotation. Diffusive enhancement\nemerges from the medium's disordered structure and peaks at a second-order\ntransition in the number of contacts. Our results reproduce the salient\nfeatures of the colloidal glass experiment and support an effective description\nthat is applicable to a broader class of viscoelastic suspensions."
    },
    {
        "anchor": "Structural Transitions and Hysteresis in Clump- and Stripe-Forming\n  Systems Under Dynamic Compression: Using numerical simulations, we study the dynamical evolution of particles\ninteracting via competing long-range repulsion and short-range attraction in\ntwo dimensions. The particles are compressed using a time-dependent quasi-one\ndimensional trough potential that controls the local density, causing the\nsystem to undergo a series of structural phase transitions from a low density\nclump lattice to stripes, voids, and a high density uniform state. The\ncompression proceeds via slow elastic motion that is interrupted with\navalanche-like bursts of activity as the system collapses to progressively\nhigher densities via plastic rearrangements. The plastic events vary in\nmagnitude from small rearrangements of particles, including the formation of\nquadrupole-like defects, to large-scale vorticity and structural phase\ntransitions. In the dense uniform phase, the system compresses through row\nreduction transitions mediated by a disorder-order process. We characterize the\nrearrangement events by measuring changes in the potential energy, the fraction\nof sixfold coordinated particles, the local density, and the velocity\ndistribution. At high confinements, we find power law scaling of the velocity\ndistribution during row reduction transitions. We observe hysteresis under a\nreversal of the compression when relatively few plastic rearrangements occur.\nThe decompressing system exhibits distinct phase morphologies, and the phase\ntransitions occur at lower compression forces as the system expands compared to\nwhen it is compressed.",
        "positive": "Confinement-induced alternating interactions between inclusions in an\n  active fluid: In a system of colloidal inclusions suspended in a thermalized bath of\nsmaller particles, the bath engenders an attractive force between the\ninclusions, arising mainly from entropic origins, known as the depletion force.\nIn the case of active bath particles, the nature of the bath-mediated force\nchanges dramatically from an attractive to a repulsive one, as the strength of\nparticle activity is increased. We study such bath-mediated effective\ninteractions between colloidal inclusions in a bath of self-propelled Brownian\nparticles, being confined in a narrow planar channel. Confinement is found to\nhave a strong effect on the interaction between colloidal particles, however,\nthis mainly depends on the colloidal orientation inside the channel. Effect of\nthe confinement on the interaction of colloidal disk is controlled by the\nlayering of active particles on the surface boundaries. This can emerge as a\ncompetitive factor, involving the tendencies of the channel walls and the\ncolloidal inclusions in accumulating the active particles in their own\nproximity."
    },
    {
        "anchor": "The short-time critical behaviour of the Ginzburg-Landau model with\n  long-range interaction: The renormalisation group approach is applied to the study of the short-time\ncritical behaviour of the $d$-dimensional Ginzburg-Landau model with long-range\ninteraction of the form $p^{\\sigma} s_{p}s_{-p}$ in momentum space. Firstly the\nsystem is quenched from a high temperature to the critical temperature and then\nrelaxes to equilibrium within the model A dynamics. The asymptotic scaling laws\nand the initial slip exponents $\\theta^{\\prime}$ and $\\theta$ of the order\nparameter and the response function respectively, are calculated to the second\norder in $\\epsilon=2\\sigma-d$.",
        "positive": "Motion of two micro-wedges in a turbulent bacterial bath: The motion of a pair of micro-wedges (\"carriers\") in a turbulent bacterial\nbath is explored using computer simulations with explicit modeling of the\nbacteria and experiments. The orientation of the two micro-wedges is parallel\nand fixed by an applied magnetic field but the translational coordinates can\nmove freely as induced by the bacterial bath. As a result, two carriers of same\norientation move such that their mutual distance decreases. Eventually the two\ncarriers stack on each other with no intervening bacteria exhibiting a stable\ndynamical mode where the two micro-wedges follow each other with the same\nvelocity. These findings are in qualitative agreement with experiments on two\nmicro-wedges in a bacterial bath. Our results provide insight into\nunderstanding the self-assembly of many micro-wedges in an active bath."
    },
    {
        "anchor": "Ordering at two length scales in comb-coil diblock copolymers consisting\n  of only two different monomers: The microphase separated morphology of a melt of a specific class of\ncomb-coil diblock copolymers, consisting of an AB comb block and a linear\nhomopolymer A block, is analyzed in the weak segregation limit. On increasing\nthe length of the homopolymer A block, the systems go through a characteristic\nseries of structural transitions. Starting from the pure comb copolymer the\nfirst series of structures involve the short length scale followed by\nstructures involving the large length scale. A maximum of two critical points\nexists. Furthermore, in the two parameter space, characterizing the comb-coil\ndiblock copolymer molecules considered, a non-trivial bifurcation point exists\nbeyond which the structure factor can have two maxima (two correlation hole\npeaks).",
        "positive": "Hydrophobic interaction in the liquid phases of globular protein\n  solutions: structure factor parameters: We develop a simple correspondence between hydrophobic surface topology of\nglobular proteins and and an effective protein-protein adhesiveness parameter\nof the Baxter type. We discuss within this framework analytical interpretation\nof the structure factor governing static light scattering."
    },
    {
        "anchor": "Dynamic self-assembly of charged colloidal strings and walls in simple\n  fluid flows: Colloidal particles can self-assemble into various ordered structures in\nfluid flows that have potential applications in biomedicine, materials\nsynthesis and encryption. These dynamic processes are also of fundamental\ninterest for probing the general principles of self-assembly in non-equilibrium\nconditions. Here, we report a simple microfluidic experiment, where charged\ncolloidal particles self-assemble into flow-aligned 1D strings with regular\nparticle spacing near a solid boundary. Using high-speed confocal microscopy,\nwe systematically investigate the influence of flow rates, electrostatics and\nparticle polydispersity on the observed string structures. By studying the\ndetailed dynamics of stable flow-driven particle pairs, we quantitatively\ncharacterize interparticle interactions. Based on the results, we construct a\nsimple model that explains the intriguing non-equilibrium self-assembly\nprocess. Our study shows that the colloidal strings arise from a delicate\nbalance between attractive hydrodynamic coupling and repulsive electrostatic\ninteraction between particles. Finally, we demonstrate that, with the\nassistance of transverse electric fields, a similar mechanism also leads to the\nformation of 2D colloidal walls.",
        "positive": "Compound redistribution due to droplet evaporation on a thin polymeric\n  film: theory: A thin polymeric film in contact with a fluid body may leach\nlow-molecular-weight compounds into the fluid. If this fluid is a small\ndroplet, the compound concentration within the liquid increases due to ongoing\nleaching in combination with the evaporation of the droplet. This may\neventually lead to an inversion of the transport process and a redistribution\nof the compounds within the thin film. In order to gain an understanding of the\ncompound redistribution, we apply a macroscopic model for the evaporation of a\ndroplet and combine that with a diffusion model for the compound transport. In\nthe model, material deposition and the resulting contact line pinning are\nassociated with the precipitation of a fraction of the dissolved material. We\nfind three power law regimes for the size of the deposit area as a function of\nthe initial droplet size, dictated by the competition between evaporation,\ndiffusion and the initial compound concentrations in the droplet and the thin\nfilm. The strength of the contact line pinning determines the deposition\nprofile of the precipitate, characterised by a pronounced edge and a linearly\ndecaying profile towards the centre of the stain. Our predictions for the\nconcentration profile within the solid substrate resemble patterns found\nexperimentally."
    },
    {
        "anchor": "Kapitza resistance at a domain boundary in linear and nonlinear chains: We explore Kapitza thermal resistance on the boundary between two homogeneous\nchain fragments with different characteristics. For a linear model, an exact\nexpression for the resistance is derived, and well-defined in the thermodynamic\nlimit. However, the resistance in this case depends on the thermostat\nproperties and therefore is not a local property of the considered domain\nboundary. If the domains are nonlinear, but integrable - Toda lattice,\nelastically colliding particles - the anomalies are similar to the case of the\nlinear chain, besides well-articulated thermal dependence of the resistance.\nFor the case of elastically colliding particles, this dependence follows a\nsimple scaling law - the resistance is proportional to the inverse square root\nof the temperature. For Fermi-Pasta-Ulam domains, both the temperature drop and\nthe heat flux decrease with the chain length, but with different exponents, so\nthe resistance vanishes in the thermodynamic limit. For the domains comprised\nof rotators, the thermal resistance exhibits the expected normal behavior.",
        "positive": "Rheology of Ring Polymer Melts: From Linear Contaminants to Ring/Linear\n  Blends: Ring polymers remain a major challenge to our current understanding of\npolymer dynamics. Experimental results are difficult to interpret because of\nthe uncertainty in the purity and dispersity of the sample. Using both\nequilibrium and non-equilibrium molecular dynamics simulations we have\nsystematically investigated the structure, dynamics and rheology of perfectly\ncontrolled ring/linear polymer blends with chains of such length and\nflexibility that the number of entanglements is up to about 14 per chain, which\nis comparable to experimental systems examined in the literature. The smallest\nconcentration at which linear contaminants increase the zero-shear viscosity of\na ring polymer melt of these chain lengths by 10% is approximately one-fifth of\ntheir overlap concentration. When the two architectures are present in equal\namounts the viscosity of the blend is approximately twice as large as that of\nthe pure linear melt. At this concentration the diffusion coefficient of the\nrings is found to decrease dramatically, while the static and dynamic\nproperties of the linear polymers are mostly unaffected. Our results are\nsupported by a primitive path analysis."
    },
    {
        "anchor": "Heterophase liquid states: Thermodynamics, structure, dynamics: An overview of theoretical results and experimental data on the\nthermodynamics, structure and dynamics of the heterophase glass-forming liquids\nis presented. The theoretical approach is based on the mesoscopic heterophase\nfluctuations model (HPFM) developed within the framework of the bounded\npartition function approach. The Fischer cluster phenomenon, glass transition,\nliquid-liquid transformations, parametric phase diagram, cooperative dynamics\nand fragility of the glass-forming liquids is considered.",
        "positive": "Statistical models for nucleic acids: ds-RNA and standard ds-DNA show specific structural differences in their\ndi-nucleotide steps, piled along the helical axis. Modeling the helices of\nshort fragments by a 3D mesoscopic Hamiltonian model, I use path integral\ntechniques to compute the average helical repeat and show that these structural\nfeatures are at the origin of the opposite twist-stretch patterns of the A- and\nB- form."
    },
    {
        "anchor": "Directional shear-jamming: In this work we, study shear reversals of dense non-Brownian suspensions\ncomposed of cohesionless elliptical particles. By numerical simulations, we\nshow that a new fragility appears for frictionless ellipses in the flowing\nstates, where particles can flow indefinitely in one direction at applied shear\nstresses but shear-jams in the other direction upon shear stress reversal. This\nnew fragility, absent in the isotropic particle case, is linked to the\ndirectional order of the elongated particles at steady shear and its\nreorientation at shear stress reversal, which forces the suspensions to pass\nthrough a more disordered state with an increased number of contacts in which\nit might get arrested.",
        "positive": "Poroelastic indentation of mechanically confined hydrogel layers: We report on the poroelastic indentation response of hydrogel thin films\ngeometrically confined within contacts with rigid spherical probes of radii in\nthe millimeter range. Poly(PEGMA) (poly(ethylene glycol)) methyl ether\nmethacrylate), poly(DMA) (dimethylacrylamide) and poly(NIPAM)\n(\\textit{N}-isopropylacrylamide) gel films with thickness less than 15 $\\mu$m\nwere grafted onto glass substrates using a thiol-ene click chemistry route.\nChanges in the indentation depth under constant applied load were monitored\nover time as a function of the film thickness and the radius of curvature of\nthe probe using an interferometric method. In addition, shear properties of the\nindented films were measured using a lateral contact method. In the case of\npoly(PEGMA) films, we show that poroelastic indentation behavior is adequately\ndescribed within the framework of an approximate contact model derived within\nthe limits of confined contact geometries. This model provides simple scaling\nlaws for the characteristic poroelastic time and the equilibrium indentation\ndepth. Conversely, deviations from this model are evidenced for poly(DMA) and\npoly(NIPAM) films. From lateral contact experiments, these deviations are found\nto result from strong changes in the shear properties as a result of glass\ntransition (poly(DMA)) or phase separation (poly(NIPAM)) phenomena induced by\nthe drainage of the confined films squeezed between the rigid substrates."
    },
    {
        "anchor": "Minimal Model for Sand Dunes: We propose a minimal model for aeolian sand dunes. It combines an analytical\ndescription of the turbulent wind velocity field above the dune with a\ncontinuum saltation model that allows for saturation transients in the sand\nflux. The model provides a qualitative understanding of important features of\nreal dunes, such as their longitudinal shape and aspect ratio, the formation of\na slip face, the breaking of scale invariance, and the existence of a minimum\ndune size.",
        "positive": "Unconventional rheological properties in systems of deformable particles: We demonstrate the existence of unconventional rheological and memory\nproperties in systems of soft-deformable particles whose energy depends on\ntheir shape, via numerical simulations. At large strains, these systems\nexperience an unconventional shear weakening transition characterized by an\nincrease in the mechanical energy and a drastic drop in shear stress, which\nstems from the emergence of short-ranged tetratic order. In these weakened\nstates, the contact network evolves reversibly under strain reversal, keeping\nmemory of its initial state, while the microscopic dynamics is irreversible."
    },
    {
        "anchor": "Hydrodynamic interactions dominate the structure of active swimmers'\n  pair distribution functions: Microswimmers often exhibit surprising patterns due to the nonequilibrium\nnature of their dynamics. Collectively, suspensions of microswimmers appear as\na liquid whose properties set it apart from its passive counterpart. To\nunderstand the impact of hydrodynamic interactions on the basic statistical\nfeatures of a microswimmer's liquid, we investigate its structure by means of\nthe pair distribution function. We perform particle-based simulations of\nmicroswimmers that include steric effects, shape anisotropy, and hydrodynamic\ninteractions. We find that hydrodynamic interactions considerably alter the\norientation-dependent pair distribution function compared to purely\nexcluded-volume models like active Brownian particles, and generally decrease\nthe structure of the liquid. Depletion regions are dominant at lower filling\nfractions, while at larger filling fraction the microswimmer liquid develops a\nstronger first shell of neighbors in specific directions, while losing\nstructure at larger distances. Our work is a first step towards a\nstatistico-mechanical treatment of the structure of microswimmer suspensions.",
        "positive": "Charge Regulation of Polyelectrolyte Gels: Swelling Transition: We study the effects of charge-regulated acid/base equilibrium on the\nswelling of polyelectrolyte gels, by considering a combination of the\nPoisson-Boltzmann theory and a two-site charge-regulation model based on the\nLangmuir adsorption isotherm. By exploring the volume change as a function of\nsalt concentration for both nano-gels and micro-gels, we identify conditions\nwhere the gel volume exhibits a discontinuous swelling transition. This\ntransition is driven exclusively by the charge-regulation mechanism and is\ncharacterized by a closed-loop phase diagram. Our predictions can be tested\nexperimentally for polypeptide gels."
    },
    {
        "anchor": "Spin-coating of moderately concentrated superparamagnetic colloids in\n  different magnetic field configurations: Spin-coating technique is very fast, cheap, reproducible, simple and needs\nless material to fabricate films of particulate systems/colloids. Their\nthickness and uniformity may be controlled by means of external fields. We\napply magnetic fields during the spin-coating of a moderately concentrated\nsuperparamagnetic colloid (made of silica coated magnetite particles). We study\nthe influence of different magnetic field configurations (homogeneous and\ninhomogeneous) on the resulting spin-coated deposits and compare experimental\nresults under various conditions. Superparamagnetic colloids behave as,\nnon-Newtonian, magnetorheological fluids. Their viscosity vary significantly\nunder applied magnetic fields. We measure and compare the effect of uniform and\nnon-uniform magnetic fields on their relative effective viscosity, using the\nspin-coated deposits and a previously existing model for simple colloids. The\nmechanisms involved in the deposits formation under different experimental\nconditions are also discussed. In particular, we show that the magnetophoretic\neffect plays an important role in the spin-coating of magnetic colloids\nsubjected to non-uniform magnetic fields. We characterize an effective\nmagnetoviscosity in non-uniform magnetic fields that is largely influenced by\nthe magnetophoretic effect that enhances the flow of the magnetic fluid.",
        "positive": "Protein Adaptive Plasticity and Night Vision: Proteins appear to be the most dramatic natural example of self-organized\nnetwork criticality (SONC), a concept that explains many otherwise apparently\nexponentially unlikely phenomena. Adaptive plasticity is a term which has\nbecome much more specific as a result of recent physiological and genetic\nstudies. Here we show that the molecular properties of rhodopsin, the\ntransmembrane protein associated with night vision, can be quantified species\nby species using the Moret-Zebende hydropathicity scale based on SONC. The\nresults show that long-range adaptive plasticity optimizes proximate species\nmolecular functionality far more effectively than one would infer using only\nstandard amino acid sequence (local similarity) tools such as BLAST for\nmultiple alignments. These results should be universal, and they suggest new\npaths for analyzing and predicting protein functionality from amino acid\nsequences alone."
    },
    {
        "anchor": "Equilibrium phase behavior of the square-well linear microphase-forming\n  model: We have recently developed a simulation approach to calculate the equilibrium\nphase diagram of particle-based microphase formers. Here, this approach is used\nto calculate the phase behavior of the square-well linear model for different\nstrengths and ranges of the linear long-range repulsive component. The results\nare compared with various theoretical predictions for microphase formation. The\nanalysis further allows us to better understand the mechanism for microphase\nformation in colloidal suspensions.",
        "positive": "Frictional half-plane contact problems subject to alternating normal and\n  shear loads and tension in the steady state: The problem of a general, symmetric contact, between elastically similar\nbodies, and capable of idealisation using half-plane theory, is studied in the\npresence of interfacial friction. It is subject to a constant set of loads -\nnormal force, shear force and bulk tension parallel with the interface -\ntogether with an oscillatory set of the same quantities, and is in the steady\nstate. Partial slip conditions are expected to ensue for a range of these\nquantities, and the permanent stick zone is explicitly established, thereby\neffectively specifying the maximum extent of the slip zones. Exact and\napproximate, easy to apply recipes are obtained."
    },
    {
        "anchor": "Exact coherent structures and phase space geometry of pre-turbulent 2D\n  active nematic channel flow: Confined active nematics exhibit rich dynamical behavior, including\nspontaneous flows, periodic defect dynamics, and chaotic `active turbulence'.\nHere, we study these phenomena using the framework of Exact Coherent\nStructures, which has been successful in characterizing the routes to high\nReynolds number turbulence of passive fluids. Exact Coherent Structures are\nstationary, periodic, quasiperiodic, or traveling wave solutions of the\nhydrodynamic equations that, together with their invariant manifolds, serve as\nan organizing template of the dynamics. We compute the dominant Exact Coherent\nStructures and connecting orbits in a pre-turbulent active nematic channel\nflow, which enables a fully nonlinear but highly reduced order description in\nterms of a directed graph. Using this reduced representation, we compute\ninstantaneous perturbations that switch the system between disparate\nspatiotemporal states occupying distant regions of the infinite dimensional\nphase space. Our results lay the groundwork for a systematic means of\nunderstanding and controlling active nematic flows in the moderate to high\nactivity regime.",
        "positive": "Diagnosing hyperuniformity in two-dimensional disordered jammed-packings\n  of soft spheres: Hyperuniformity characterizes a state of matter for which density\nfluctuations diminish towards zero at the largest length scales. However, the\ntask of determining whether or not an experimental system is hyperuniform is\nexperimentally challenging due to finite-resolution, noise and sample-size\neffects that influence characterization measurements. Here we explore these\nissues, employing video optical microscopy to study hyperuniformity phenomena\nin disordered two-dimensional jammed packings of soft spheres. Using a\ncombination of experiment and simulation we characterize the detrimental\neffects of particle polydispersity, image noise, and finite-size effects on the\nassignment of hyperuniformity, and we develop a methodology that permits\nimproved diagnosis of hyperuniformity from real-space measurements. The key to\nthis improvement is a simple packing reconstruction algorithm that incorporates\nparticle polydispersity to minimize free volume. In addition, simulations show\nthat hyperuniformity can be ascertained more accurately in direct space than in\nreciprocal space as a result of finite sample-size. Finally, experimental\ncolloidal packings of soft polymeric spheres are shown to be hyperuniform."
    },
    {
        "anchor": "Diffusive Evolution of Stable and Metastable Phases I: Local Dynamics of\n  Interfaces: We find analytical solutions to the Cahn-Hilliard equation for the dynamics\nof an interface in a system with a conserved order parameter (Model B). We show\nthat, although steady-state solutions of Model B are unphysical in the\nfar-field, they shed light on the local dynamics of an interface. Exact\nsolutions are given for a particular class of order-parameter potentials, and\nan expandable integral equation is derived for the general case. As well as\nrevealing some generic properties of interfaces moving under condensation or\nevaporation, the formalism is used to investigate two distinct modes of\ninterface propagation in systems with a metastable potential well. Given a\nsufficient transient increase in the flux of material onto a condensation\nnucleus, the normal motion of the interface can be disrupted by interfacial\nunbinding, leading to growth of a macroscopic amount of a metastable phase.",
        "positive": "Aggregation Dynamics of Active Rotating Particles in Dense Passive Media: Active matter systems are able to exhibit emergent non-equilibrium states due\nto activity-induced effective interactions between the active particles. Here\nwe study the aggregation and dynamical behavior of active rotating particles,\nspinners, embedded in 2D passive colloidal monolayers, which constitutes one\nsuch non-equilibrium process. Using both experiments and simulations we observe\naggregation of active particles or spinners whose behavior resembles classical\n2D coarsening. The aggregation behavior and spinner attraction depends on the\nmechanical properties of the passive monolayer and the activity of spinners.\nSpinner aggregation only occurs when the passive monolayer behaves elastically\nand when the spinner activity exceeds a minimum activity threshold.\nInterestingly for the spinner concentrations investigated here, the spinner\nconcentration doesn't seem to change the dynamics of the aggregation behavior.\nThere is also a characteristic cluster size at which the dynamics of spinner\naggregation is maximized as drag through the passive monolayer is minimized and\nthe stress applied on the passive medium is maximized. We also show that a\nternary mixture of passive particles, co-rotating, and counter-rotating\nspinners also aggregates into clusters of co and counter-rotating spinners\nrespectively."
    },
    {
        "anchor": "Rheology and dynamical heterogeneity in frictionless beads at jamming\n  density: We investigate the rheological properties of an assembly of inelastic (but\nfrictionless) particles close to the jamming density using numerical\nsimulation, in which uniform steady states with a constant shear rate\n$\\dot\\gamma$ is realized. The system behaves as a power-law fluid and the\nrelevant exponents are estimated; e.g., the shear stress is proportional to\n$\\dot\\gamma^{1/\\delta_S}$, where $1/\\delta_S=0.64(2)$. It is also found that\nthe relaxation time $\\tau$ and the correlation length $\\xi$ of the velocity\nincrease obeying power laws: $\\tau\\sim\\dot\\gamma^{-\\beta}$ and\n$\\xi\\sim\\dot\\gamma^{-\\alpha}$, where $\\beta=0.27(3)$ and $\\alpha=0.23(3)$.",
        "positive": "Testing the isomorph invariance of the bridge functions of Yukawa\n  one-component plasmas. I. Intermediate and long range: It has been recently conjectured that bridge functions remain nearly\ninvariant along phase diagram lines of constant excess entropy for the broad\nclass of R-simple liquids. To test this hypothesis, the bridge functions of\nYukawa systems are computed outside the correlation void with the\nOrnstein-Zernike inversion method and structural input from ultra-accurate\nmolecular dynamics simulations. The effect of statistical, grid, finite-size,\ntail and isomorphic errors is quantified. Uncertainty propagation analysis is\ncomplemented with a detailed investigation of the sensitivity of the bridge\nfunction to periodic and aperiodic multiplicative perturbations in the radial\ndistribution function. In the long and intermediate range, bridge functions are\ndemonstrated to be approximately isomorph invariant."
    },
    {
        "anchor": "Rotational Dynamics and Angular Locking of Nanoparticles at liquid\n  Interfaces: Nanoparticles with different surface morphologies that straddle the interface\nbetween two immiscible liquids are studied via molecular dynamics simulations.\nThe methodology employed allows us to compute the interfacial free energy at\ndifferent angular orientations of the nanoparticle. Due to their atomistic\nnature, the studied nanoparticles present both microscale and macroscale\ngeometrical features and cannot be accurately modeled as a perfectly smooth\nbody (e.g., spheres, cylinders). Under certain physical conditions, microscale\nfeatures can produce free energy barriers that are much larger than the thermal\nenergy of the surrounding media. The presence of these energy barriers can\neffectively \"lock\" the particle at specific angular orientations with respect\nto the liquid-liquid interface. This work provides new insights on the\nrotational dynamics of Brownian particles at liquid interfaces and suggests\npossible strategies to exploit the effects of microscale features with given\ngeometric characteristics.",
        "positive": "Non-monotonic effect of confinement on the glass transition: The relaxation dynamics of glass forming liquids and their structure are\ninfluenced in the vicinity of confining walls. In view of the great potential\nof this effect for applications in those fields of science and industry, where\nliquids occur under strong confinement (e.g., nano-technology), the number of\nresearchers studying various aspects and consequences of this non-monotonic\nbehaviour has been rapidly growing. This review aims at providing an overview\nof the research activity in this newly emerging field. We first briefly discuss\nhow competing mechanisms such as packing effects and short-range attraction may\nlead to a non-monotonic glass transition scenario in the bulk. We then analyse\nconfinement effects on the dynamics of fluids using a thermodynamic route which\nrelates the single particle dynamics to the excess entropy. Moreover, relating\nthe diffusive dynamics to the Widom's insertion probability, the oscillations\nof the local dynamics with density at moderate densities are fairly well\ndescribed. At high densities belonging to the supercooled regime, however, this\napproach breaks down signaling the onset of strongly collective effects.\nIndeed, confinement introduces a new length scale which in the limit of high\ndensities and small pore sizes competes with the short-range local order of the\nfluid. This gives rise to a non-monotonic dependence of the packing structure\non confinement, with a corresponding effect on the dynamics of structural\nrelaxation. This non-monotonic effect occurs also in the case of a cone-plate\ntype channel, where the degree of confinement varies with distance from the\napex. This is a very promising issue for future research with the possibility\nof uncovering the existence of alternating glassy and liquid-like domains."
    },
    {
        "anchor": "Random packing in three dimensions: Unraveling the complexities of random packing in three dimensions has long\npuzzled physicists. While both experiments and simulations consistently show a\nmaximum density of 64 percent for tightly packed random spheres, we still lack\nan unambiguous and universally accepted definition of random packing. This\npaper introduces an innovative standpoint, depicting random packing as spheres\nclosest to a quenched Poisson field of random points. We furnish an efficacious\nalgorithm to probe this proposed model numerically. We unearth a unique\nout-of-equilibrium thermodynamic phenomenon, akin to a `latent heat', that\nemerges at $\\phi_J \\approx 0.65$ in three dimensions. This phenomenon is\naccompanied by global and local structural rearrangements, marking a jamming\ntransition from an unjammed state to a jammed one. Notably, such a `jamming'\ntransition is absent for two-dimensional random packing. Our innovative\napproach paves a new avenue for defining random packing and provides novel\ninsights into the behavior of amorphous materials.",
        "positive": "Bridging Pico-to-Nanonewtons with a Ratiometric Force Probe for\n  Monitoring Nanoscale Polymer Physics Before Damage: Understanding the transmission of nanoscale forces in the pico-to-nanonewton\nrange is important in polymer physics. While physical approaches have\nlimitations in analyzing the local force distribution in condensed\nenvironments, chemical analysis using force probes is promising. However, there\nare stringent requirements for probing the local forces generated before\nstructural damage. The magnitude of those forces corresponds to the range below\ncovalent bond scission (from 200 pN to several nN) and above thermal\nfluctuation (several pN). Here, we report a conformationally flexible\ndual-fluorescence force probe with a theoretically estimated threshold of\napproximately 100 pN. This probe enables ratiometric analysis of the\ndistribution of local forces in a stretched polymer chain network. Without\nchanging the intrinsic properties of the polymer, the force distribution was\nreversibly monitored in real time. Chemical control of the probe location\ndemonstrated that the local stress concentration is twice as biased at\ncrosslinkers than at main chains, particularly in a strain-hardening region.\nDue to the high sensitivity, the percentage of stressed force probes was\nestimated to be more than 1000 times higher than the activation rate of a\nconventional mechanophore."
    },
    {
        "anchor": "Liquid nanofilms. A mechanical model for the disjoining pressure: Liquids in contact with solids are submitted to intermolecular forces making\nliquids heterogeneous and, in a mechanical model, the stress tensor is not any\nmore spherical as in homogeneous bulks. The aim of this article is to show that\na square-gradient functional taking into account the volume liquid free energy\ncorrected with two surface liquid density functionals is a mean field\napproximation allowing to study structures of very thin liquid nanofilms near\nplane solid walls. The model determines analytically the concept of disjoining\npressure for liquid films of thicknesses of a very few number of nanometers and\nyields a behavior in good agreement with the shapes of experimental curves\ncarried out by Derjaguin and his successors.",
        "positive": "Nucleation and structural growth of cluster crystals: We study the nucleation of crystalline cluster phases in the generalized\nexponential model with exponent n=4. Due to the finite value of this pair\npotential for zero separation, at high densities the system forms cluster\ncrystals with multiply occupied lattice sites. Here, we investigate the\nmicroscopic mechanisms that lead to the formation of cluster crystals from a\nsupercooled liquid in the low-temperature region of the phase diagram. Using\nmolecular dynamics and umbrella sampling, we calculate the free energy as a\nfunction of the size of the largest crystalline nucleus in the system, and\ncompare our results with predictions from classical nucleation theory.\nEmploying bond-order parameters based on a Voronoi tessellation to distinguish\ndifferent crystal structures, we analyze the average composition of crystalline\nnuclei. We find that even for conditions where a multiply-occupied fcc crystal\nis the thermodynamically stable phase, the nucleation into bcc cluster crystals\nis strongly preferred. Furthermore, we study the particle mobility in the\nsupercooled liquid and in the cluster crystal. In the cluster crystal, the\nmotion of individual particles is captured by a simple reaction-diffusion model\nintroduced previously to model the kinetics of hydrogen bonds."
    },
    {
        "anchor": "Surface defects in vesicle aggregates and anyons: We consider surface defects in connection to the closed vesicle form\nevolution in mesomorphism of lyotropic aggregates, based on the experimental\ndata by Feigenson \\cite{Feig} on confocal fluorescent resonant microscopy for\nthe lipid $DPPC/ DLPC$/cholesterol system. To estimate the influence of surface\ntopological defects onto aggregate form it has been used the fractional quantum\nHall effect (FQHE) description \\cite{EPL1992}, \\cite{Haldane1}.",
        "positive": "Droplets capped with an elastic film can be round, elliptical, or nearly\n  square: We present experiments which show that the partial wetting of droplets capped\nby taut elastic films is highly tunable. Adjusting the tension allows the\ncontact angle and droplet morphology to be controlled. By exploiting these\nelastic boundaries, droplets can be made elliptical, with an adjustable aspect\nratio, and can even be transformed into a nearly square shape. This system can\nbe used to create tunable liquid lenses, and moreover, presents a unique\napproach to liquid patterning."
    },
    {
        "anchor": "Topotaxis of Active Particles Induced by Spatially Heterogeneous Sliding\n  along Obstacles: Many biological active agents respond to gradients of environmental cues by\nredirecting their motion. Besides the well-studied prominent examples such as\nphoto- and chemotaxis, there has been considerable recent interest in\ntopotaxis, i.e.\\ the ability to sense and follow topographic environmental\ncues. We numerically investigate the topotaxis of active agents moving in\nregular arrays of circular pillars. While a trivial topotaxis is achievable\nthrough a spatial gradient of obstacle density, here we show that imposing a\ngradient in the characteristics of agent-obstacle interaction can lead to an\neffective topotaxis in an environment with a spatially uniform density of\nobstacles. As a proof of concept, we demonstrate how a gradient in the angle of\nsliding around pillars -- as e.g.\\ observed in bacterial dynamics near surfaces\n-- breaks the spatial symmetry and biases the direction of motion. We provide\nan explanation for this phenomenon based on effective reflection at the\nimaginary interface between pillars with different sliding angles. Our results\nare of technological importance for design of efficient taxis devices.",
        "positive": "Surface-Directed Spinodal Decomposition: A Molecular Dynamics Study: We use molecular dynamics (MD) simulations to study surface-directed spinodal\ndecomposition (SDSD) in unstable binary ($AB$) fluid mixtures at wetting\nsurfaces. The thickness of the wetting layer $R_1$ grows with time $t$ as a\npower-law ($R_1 \\sim t^\\theta$). We find that hydrodynamic effects result in a\ncrossover of the growth exponent from $\\theta\\simeq 1/3$ to $\\theta\\simeq1$. We\nalso present results for the layer-wise correlation functions and domain length\nscales."
    },
    {
        "anchor": "Correlations of strain and plasticity in flowing foam: Via simulations of flowing foam, we connect the high and intermediate density\nregimes of complex fluid flows into a consistent microscopic picture of\ndeformation. While at and above the jamming transition, elastic correlations\nlead to strong spatial organization of the flow field, below jamming, the\nslowly diminishing elastic correlation length leads to slowly ceasing spatial\norganization, which is nevertheless still present down to densities far below\njamming. We show that the long-range correlated flow field arises from the\nsuperposition of quadrupolar strain fields of shear zones with highly\ncorrelated positions, strengths and orientation. These interactions are still\npertinent below jamming, where they systematically weaken with the slowly\ndiminishing elastic correlation length. These results demonstrate the ubiquity\nand importance of elastic correlations in the flow of complex fluids even below\nthe jamming transition, and motivate a scale-bridging description of their flow\nover wide ranges of density from solid to fluid.",
        "positive": "Rising obstacle in a one-layer granular bed induced by continuous\n  vibrations: two dynamical regimes governed by vibration velocity: Rising motion of an obstacle in a vibrated granular medium is a classic\nproblem of granular segregation, and called the Brazil nut (BN) effect. The\ncontrolling vibration parameters of the effect has been a long-standing\nproblem. A simple possibility that the BN effect can be characterized solely by\nvibration velocity has recently been pointed out. The issue has become\ncontroversial before a long history of research, with only a few systems have\nprovided for the simple possibility. Here, we investigate the rising motion of\nan obstacle in a vertically positioned one-layer granular bed under continuous\nvibrations. We find the rising motion is composed of two distinct regimes, and\nthe first and second regimes are both governed, in terms of vibration\nparameters, solely by the vibration velocity. We further demonstrate simple\nscaling laws well describe the two regimes. Our results support the emergent\npossibility on the controlling parameters of the BN effect and suggests that\nthis feature would be universal. We propose two possible mechanisms of\nconvection and arch effect for the two distinct regimes and demonstrate these\nmechanism explain the scaling laws followed by our experimental data."
    },
    {
        "anchor": "Transitions between phyllotactic lattice states in curved geometries: Phyllotaxis, the regular arrangement of leaves or other lateral organs in\nplants including pineapples, sunflowers and some cacti, has attracted\nscientific interest for centuries. More recently there has been interest in\nphyllotaxis within physical systems, especially for cylindrical geometry. In\nthis letter, we expand from a cylindrical geometry and investigate transitions\nbetween phyllotactic states of soft vortex matter confined to a conical\nfrustum. We show that the ground states of this system are consistent with\nprevious results for cylindrical confinement and discuss the resulting defect\nstructures at the transitions. We then eliminate these defects from the system\nby introducing a density gradient to create a configuration in a single state.\nThe nature of the density gradient limits this approach to a small parameter\nrange on the conical system. We therefore seek a new surface, the horn, for\nwhich a defect-free state can be maintained for a larger range of parameters.",
        "positive": "Stability of jammed packings I: the rigidity length scale: In 2005, Wyart et al. (Europhys. Lett., 72 (2005) 486) showed that the low\nfrequency vibrational properties of jammed amorphous sphere packings can be\nunderstood in terms of a length scale, called l*, that diverges as the system\nbecomes marginally unstable. Despite the tremendous success of this theory, it\nhas been difficult to connect the counting argument that defines l* to other\nlength scales that diverge near the jamming transition. We present an alternate\nderivation of l* based on the onset of rigidity. This phenomenological approach\nreveals the physical mechanism underlying the length scale and is relevant to a\nrange of systems for which the original argument breaks down. It also allows us\nto present the first direct numerical measurement of l*."
    },
    {
        "anchor": "Deformation of a soft boundary induced and enhanced by enclosed active\n  particles: We simulate a two dimensional model of self-propelled particles confined by a\ndeformable boundary. The particles tend to accumulate near the boundary and the\nshape of the boundary deforms upon the collisions. We find that there are two\ntypical stages in the variation of the morphology with the increase of active\nforce. One is at small force characterized by radially inhomogeneous\nredistribution of particles and suppression of local fluctuations of the\nboundary. The other is at large force featured by angularly redistribution of\nparticles and global shape deformation of the boundary. The last two processes\nare strongly cooperative. We also find different mechanisms in the particle\nredistribution and opposite force-dependences of the rate of the shape\nvariation at low and high particle concentrations.",
        "positive": "Machine learning topological defects in confluent tissues: Active nematics is an emerging paradigm for characterising biological\nsystems. One aspect of particularly intense focus is the role active nematic\ndefects play in these systems, as they have been found to mediate a growing\nnumber of biological processes. Accurately detecting and classifying these\ndefects in biological systems is, therefore, of vital importance to improving\nour understanding of such processes. While robust methods for defect detection\nexist for systems of elongated constituents, other systems, such as epithelial\nlayers, are not well suited to such methods. Here, we address this problem by\ndeveloping a convolutional neural network to detect and classify nematic\ndefects in confluent cell layers. Crucially, our method is readily\nimplementable on experimental images of cell layers and is specifically\ndesigned to be suitable for cells that are not rod-shaped. We demonstrate that\nour machine learning model outperforms current defect detection techniques and\nthat this manifests itself in our method requiring less data to accurately\ncapture defect properties. This could drastically improve the accuracy of\nexperimental data interpretation whilst also reducing costs, advancing the\nstudy of nematic defects in biological systems."
    },
    {
        "anchor": "Length distribution of stiff, self-assembled polymers at thermal\n  equilibrium: We investigate the length distribution of self-assembled, long and stiff\npolymers at thermal equilibrium. Our analysis is based on calculating the\npartition functions of stiff polymers of variable lengths in the elastic\nregime. Our conclusion is that the length distribution of this self-assembled\nsystem follows closely the exponential distribution, except at the short length\nlimit. We then discuss the implications of our results on the experimentally\nobserved length distributions in amyloid fibrils.",
        "positive": "Simple model for reverse buoyancy in a vibrated granular system: Large objects, immersed in a homogeneous granular system, migrate when\nsubjected to vibrations. Under certain conditions large heavy objects rise and\nsimilar light ones sink to the bottom. This is called reverse buoyancy. We\nreport an experimental study of this singular behavior, for a large sphere\nimmersed in a deep granular bed. A simple mechanism is proposed to describe the\nmotion of a sphere, inside a vertically vibrated granular system. When reverse\nbuoyancy is observed, the measured vertical velocity of the immersed object, as\na function of its density, shows a simple behavior. With a one-dimensional\nmechanical model that takes into account a buoyancy force and the frictional\ndrag, we obtain the rising velocity for heavy objects and the sinking rate for\nlight ones. The model yields a very good qualitative and quantitative agreement\nwith the experiment."
    },
    {
        "anchor": "Polymer translocation through a nanopore under a pulling force: We investigate polymer translocation through a nanopore under a pulling force\nusing Langevin dynamics simulations. We concentrate on the influence of the\nchain length $N$ and the pulling force $F$ on the translocation time $\\tau$.\nThe distribution of $\\tau$ is symmetric and narrow for strong $F$. We find that\n$\\tau\\sim N^{2}$ and translocation velocity $v\\sim N^{-1}$ for both moderate\nand strong $F$. For infinitely wide pores, three regimes are observed for\n$\\tau$ as a function of $F$. With increasing $F$, $\\tau$ is independent of $F$\nfor weak $F$, and then $\\tau\\sim F^{-2+\\nu^{-1}}$ for moderate $F$, where $\\nu$\nis the Flory exponent, which finally crosses over to $\\tau\\sim F^{-1}$ for\nstrong force. For narrow pores, even for moderate force $\\tau\\sim F^{-1}$.\nFinally, the waiting time, for monomer $s$ and monomer $s+1$ to exit the pore,\nhas a maximum for $s$ close to the end of the chain, in contrast to the case\nwhere polymer is driven by an external force within the pore.",
        "positive": "Translational and rotational non-Gaussianities in homogeneous freely\n  evolving granular gases: The importance of roughness in the modeling of granular gases has been\nincreasingly considered in recent years. In this paper, a freely evolving\nhomogeneous granular gas of inelastic and rough hard disks or spheres is\nstudied under the assumptions of the Boltzmann kinetic equation. The\nhomogeneous base state reached by the system is studied from a theoretical\npoint of view using a Sonine approximation, in contrast to a previous\nMaxwellian approach. A general theoretical description is done in terms of\n$d_t$ translational and $d_r$ rotational degrees of freedom, which accounts for\nthe cases of spheres ($d_t=d_r=3$) and disks ($d_t=2$, $d_r=1$) within a\nunified framework. The non-Gaussianities of the velocity distribution function\nof this state are determined by means of the first nontrivial cumulants and by\nthe derivation of non-Maxwellian high-velocity tails. The results are validated\nby computer simulations using direct simulation Monte Carlo and event-driven\nmolecular dynamics algorithms."
    },
    {
        "anchor": "Discontinuous shear-thinning in adhesive dispersions: We present simulations for the steady-shear rheology of a model adhesive\ndispersion. We vary the range of the attractive forces $u$ as well as the\nstrength of the dissipation $b$. For large dissipative forces, the rheology is\ngoverned by the Weisenberg number $ \\text{Wi}\\sim b\\dot\\gamma/u$ and displays\nHerschel-Bulkley form $\\sigma = \\sigma_y+c\\text{Wi}^\\nu$ with exponent\n$\\nu=0.45$. Decreasing the strength of dissipation, the scaling with\n$\\text{Wi}$ breaks down and inertial effects show up. The stress decreases via\nthe Johnson-Samwer law $\\Delta\\sigma\\sim T_s^{2/3}$, where temperature $T_s$ is\nexclusively due to shear-induced vibrations. During flow particles prefer to\nrotate around each other such that the dominant velocities are directed\ntangentially to the particle surfaces. This tangential channel of energy\ndissipation and its suppression leads to a discontinuity in the flow curve, and\nan associated discontinuous shear thinning transition. We set up an analogy\nwith frictional systems, where the phenomenon of discontinuous shear thickening\noccurs. In both cases tangential forces, frictional or viscous, mediate a\ntransition from one branch of the flowcurve with low tangential dissipation to\none with large tangential dissipation.",
        "positive": "Nucleation-induced transition to collective motion in active systems: While the existence of polar ordered states in active systems is well\nestablished, the dynamics of the self-assembly processes are still elusive. We\nstudy a lattice gas model of self-propelled elongated particles interacting\nthrough excluded volume and alignment interactions, which shows a phase\ntransition from an isotropic to a polar ordered state. By analyzing the\nordering process we find that the transition is driven by the formation of a\ncritical nucleation cluster and a subsequent coarsening process. Moreover, the\ntime to establish a polar ordered state shows a power-law divergence."
    },
    {
        "anchor": "Emergence of structural anisotropy in Optical Glasses treated to support\n  Second Harmonic Generation: Structural alterations in v-SiO2 induced by \"thermal poling\", a treatment\nwhich makes the glass able to double the frequency of an impinging infrared\nlight, are revealed by neutron diffraction as a breakdown of the macroscopic\nisotropy. This leads to concomitant changes in the vibrational density of\nstates measured by inelastic neutron scattering. The observations are found to\nbe consistent with the emergence of partial ordering within the glassy matrix\nalong the direction of an electrostatic field applied during the poling\ntreatment.",
        "positive": "Surface induced ordering in thin film diblock copolymers: tilted\n  lamellar phases: We investigate the effect of chemically patterned surfaces on the morphology\nof diblock copolymers below the order-disorder transition. Profiles for\nlamellar phases in contact with one surface, or confined between two surfaces\nare obtained in the weak segregation limit using a Ginzburg-Landau expansion of\nthe free energy, and treating it with mean-field theory. The periodically\npatterned surface induces a tilt of the lamellae in order to match the surface\nperiodicity. The lamellae relax from the constrained periodicity close to the\nsurface to the bulk periodicity far from it. The phases we investigate are a\ngeneralization to the mixed (perpendicular and parallel to the surface)\nlamellar phases occurring when the two surfaces are homogeneous. A special case\nwhen the surface pattern has a period equal to the bulk lamellar period showing\n``T-junction'' morphology is examined. Our analytic calculation agrees with\nprevious computer simulations and self consistent field theories."
    },
    {
        "anchor": "Lattice Boltzmann for Binary Fluids with Suspended Colloids: A new description of the binary fluid problem via the lattice Boltzmann\nmethod is presented which highlights the use of the moments in constructing two\nequilibrium distribution functions. This offers a number of benefits, including\nbetter isotropy, and a more natural route to the inclusion of multiple\nrelaxation times for the binary fluid problem. In addition, the implementation\nof solid colloidal particles suspended in the binary mixture is addressed,\nwhich extends the solid-fluid boundary conditions for mass and momentum to\ninclude a single conserved compositional order parameter. A number of simple\nbenchmark problems involving a single particle at or near a fluid-fluid\ninterface are undertaken and show good agreement with available theoretical or\nnumerical results.",
        "positive": "Fluid - solid transition in simple systems using density functional\n  theory: A free energy functional for a crystal proposed by Singh and Singh\n(Europhysics Letters \\textbf{88}, 16005 (2009)) which contains both the\nsymmetry-conserved and symmetry-broken parts of the direct pair correlation\nfunction has been used to investigate the fluid-solid transition in systems\ninteracting via purely repulsive WCA Lennard - Jones (RLJ) potential and the\nfull Lennard - Jones (LJ) potential. The results found for freezing parameters\nfor the fluid - face centred cubic (fcc) crystal transition are in very good\nagreement with simulation results. It is shown that although the contribution\nmade by the symmetry broken part to the grand thermodynamic potential at the\nfreezing point is small compared to that of the symmetry conserving part, its\nrole is crucial in stabilizing the crystalline structure and on values of\nfreezing parameters. The effect of attractive part of the LJ potential on the\nfreezing parameters is found to be small, confirming the view that the fluid -\nsolid transition is primarily determined by the repulsive part of the\npotential."
    },
    {
        "anchor": "Hydrodynamic coupling of two rotating spheres trapped in harmonic\n  potentials: We theoretically study in detail the hydrodynamic coupling of two equal-sized\ncolloidal spheres at low Reynolds numbers assuming the particles to be\nharmonically trapped with respect to both their positions and orientations. By\ntaking into account the rotational motion, we obtain a rich spectrum of\ncollective eigen modes whose properties we determine on the basis of pure\nsymmetry arguments. Extending recent investigations on translational\ncorrelations [J.-C. Meiners and S. R. Quake, Phys. Rev. Lett. 82, 2211 (1999)],\nwe derive the complete set of auto- and cross-correlation functions emphasizing\nthe coupling of rotation to translation which we illustrate in a few examples.\nAn important feature of our system is the self-coupling of translation and\nrotation of one particle mediated by the neighboring particle that is clearly\nvisible in the appropriate auto-correlation function. This coupling is a\nhigher-order effect and therefore not included in the widely used Rotne-Prager\napproximation for the hydrodynamic mobilities.",
        "positive": "Colloidal templating at a cholesteric - oil interface: Assembly guided\n  by an array of disclination lines: We simulate colloids (radius $R \\sim 1\\mu$m) trapped at the interface between\na cholesteric liquid crystal and an immiscible oil, at which the helical order\n(pitch p) in the bulk conflicts with the orientation induced at the interface,\nstabilizing an ordered array of disclinations. For weak anchoring strength W of\nthe director field at the colloidal surface, this creates a template, favoring\nparticle positions eitheron top of or midway between defect lines, depending on\n$\\alpha = R/p$. For small $\\alpha$, optical microscopy experiments confirm this\npicture, but for larger $\\alpha$ no templating is seen. This may stem from the\nemergence at moderate W of a rugged energy landscape associated with defect\nreconnections."
    },
    {
        "anchor": "Exotic states of matter in an oscillatory driven liquid crystal cell: Matter under different equilibrium conditions of pressure and temperature\nexhibits different states such as solid, liquid, gas, and plasma. Exotic states\nof matter, such as Bose- Einstein condensates, superfluidity, chiral magnets,\nsuperconductivity, and liquid crystalline blue phases are observed in\nthermodynamic equilibrium. Rather than being a result of an aggregation of\nmatter, their emergence is due to a change of a topological state of the\nsystem. Here we investigate topological states of matter in a system with\ninjection and dissipation of energy. In an experiment involving a liquid\ncrystal cell under the influence of a low-frequency oscillatory electric field,\nwe observe a transition from non-vortex state to a state in which vortices\npersist. Depending on the period and the type of the forcing, the vortices\nself-organise forming square lattices, glassy states, and disordered vortex\nstructures. Based on a stochastic amplitude equation, we recognise the origin\nof the transition as the balance between stochastic creation and deterministic\nannihilation of vortices. Our results show that the matter maintained out of\nequilibrium by means of the temporal modulation of parameters can exhibit\nexotic states.",
        "positive": "Decorated vertices with 3-edged cells in 2D foams: exact solutions and\n  properties: The energy, area and excess energy of a decorated vertex in a 2D foam are\ncalculated. The general shape of the vertex and its decoration are described\nanalytically by a reference pattern mapped by a parametric Moebius\ntransformation. A single parameter of control allows to describe, in a common\nframework, different types of decorations, by liquid triangles or 3-sided\nbubbles, and other non-conventional cells. A solution is proposed to explain\nthe stability threshold in the flower problem."
    },
    {
        "anchor": "Critical number of atoms for attractive Bose-Einstein condensates with\n  cylindrically symmetrical traps: We calculated, within the Gross-Pitaevskii formalism, the critical number of\natoms for Bose-Einstein condensates with two-body attractive interactions in\ncylindrical traps with different frequency ratios. In particular, by using the\ntrap geometries considered by the JILA group [Phys. Rev. Lett. 86, 4211\n(2001)], we show that the theoretical maximum critical numbers are given\napproximately by $N_c = 0.55 ({l_0}/{|a|})$. Our results also show that, by\nexchanging the frequencies $\\omega_z$ and $\\omega_\\rho$, the geometry with\n$\\omega_\\rho < \\omega_z$ favors the condensation of larger number of particles.\nWe also simulate the time evolution of the condensate when changing the ground\nstate from $a=0$ to $a<0$ using a 200ms ramp. A conjecture on higher order\nnonlinear effects is also added in our analysis with an experimental proposal\nto determine its signal and strength.",
        "positive": "Monte Carlo simulation of the nonadditive restricted primitive model of\n  ionic fluids: Phase diagram and clustering: We report an accurate Monte Carlo calculation of the phase diagram and\nclustering properties of the restricted primitive model with non-additive\nhard-sphere diameters. At high density the positively non-additive fluid shows\nmore clustering than the additive model and the negatively non-additive fluid\nshows less clustering than the additive model, at low density the reverse\nscenario appears. A negative nonadditivity tends to favor the formation of\nneutrally charged clusters starting from the dipole. A positive nonadditivity\nfavors the pairing of like ions at high density. The critical point of the\ngas-liquid phase transition moves at higher temperatures and higher densities\nfor a negative nonadditivity and at lower temperatures and lower densities for\na positive nonadditivity. The law of corresponding states does not seem to hold\nstrictly. Our results can be used to interpret recent experimental works on\nroom temperature ionic liquids."
    },
    {
        "anchor": "Identifying the Onset of Phase Separation in Quaternary Lipid Bilayer\n  Systems from Coarse-Grained Simulations: Understanding the (de)mixing behavior of multicomponent lipid bilayers is an\nimportant step towards unraveling the nature of spatial composition\nheterogeneities in cellular membranes and their role in biological function. We\nuse coarse-grained molecular dynamics simulations to study the composition\nphase diagram of a quaternary mixture of phospholipids and cholesterol. This\nmixture is known to exhibit both uniform and coexisting phases. We compare and\ncombine different statistical measures of membrane structure to identify the\nonset of phase coexistence in composition space. An important element in our\napproach is the dependence of composition heterogeneities on the size of the\nsystem. While homogeneous phases can be structured and display long correlation\nlengths, the hallmark behavior of phase coexistence is the scaling of the\napparent correlation length with system size. Because the latter cannot be\neasily varied in simulations, our method instead uses information obtained from\nobservation windows of different sizes to accurately distinguish phase\ncoexistence from structured homogeneous phases. This approach is built on very\ngeneral physical principles, and will be beneficial to future studies of the\nphase behavior of multicomponent lipid bilayers.",
        "positive": "Nonuniversal routes to universality: Critical phenomena in colloidal\n  dispersions: We investigate critical phenomena in colloids by means of the\nrenormalization-group based hierarchical reference theory of fluids (HRT). We\nfocus on three experimentally relevant model systems: namely, the\nAsakura-Oosawa model of a colloidal dispersion under the influence of\npolymer-induced attractive depletion forces; fluids with competing short-range\nattractive and longer-range repulsive interactions; solutions of star-polymers\nwhose pair potential presents both an attractive well and an ultrasoft\nrepulsion at shorter distance. Our results show that the ability to tune the\neffective interactions between colloidal particles allows one to generate a\nvariety of crossovers to the asymptotic critical behavior, which are not\nobserved in atomic fluids."
    },
    {
        "anchor": "Competitive sorption of mono- versus di-valent ions by highly charged\n  globular macromolecules: When a highly charged globular macromolecule, such as a dendritic\npolyelectrolyte or charged nanogel, is immersed into a physiological\nelectrolyte solution, monovalent and divalent counterions from the solution\nbind to the macromolecule in a certain ratio and thereby almost completely\nelectroneutralize it. For charged macromolecules in biological media, the\nnumber ratio of bound mono- versus di-valent ions is decisive for the desired\nfunction. A theoretical prediction of such a sorption ratio is challenging\nbecause of the competition of electrostatic (valency), ion-specific, and\nbinding saturation effects. Here, we devise and discuss a few approximate\nmodels to predict such an equilibrium sorption ratio by extending and combining\nestablished electrostatic binding theories such as Donnan, Langmuir, Manning as\nwell as Poisson-Boltzmann approaches, to systematically study the competitive\nuptake of mono- and di-valent counterions by the macromolecule. We compare and\nfit our models to coarse-grained (implicit-solvent) computer simulation data of\nthe globular polyelectrolyte dendritic polyglycerol sulfate (dPGS) in salt\nsolutions of mixed valencies. The dPGS has high potential to serve in\nmacromolecular carrier applications in biological systems and at the same time\nconstitutes a good model system for a highly charged macromolecule. We finally\nuse the simulation-informed models to extrapolate and predict electrostatic\nfeatures such as the effective charge as a function of the divalent ion\nconcentration for a wide range of dPGS generations (sizes).",
        "positive": "Slow, non-diffusive dynamics in concentrated nanoemulsions: Using multispeckle x-ray photon correlation spectroscopy, we have measured\nthe slow, wave-vector dependent dynamics of concentrated, disordered\nnanoemulsions composed of silicone oil droplets in water. The intermediate\nscattering function possesses a compressed exponential lineshape and a\nrelaxation time that varies inversely with wave vector. We interpret these\ndynamics as strain in response to local stress relaxation. The motion includes\na transient component whose characteristic velocity decays exponentially with\ntime following a mechanical perturbation of the nanoemulsions and a second\ncomponent whose characteristic velocity is essentially independent of time. The\nsteady-state characteristic velocity is surprisingly insensitive to droplet\nvolume fraction in the concentrated regime, indicating that the strain motion\nis only weakly dependent on the droplet-droplet interactions."
    },
    {
        "anchor": "Dynamical quantum noise in Bose-Einstein condensates: We introduce the study of dynamical quantum noise in Bose-Einstein\ncondensates through numerical simulation of stochastic partial differential\nequations obtained using phase space representations. We derive evolution\nequations for a single trapped condensate in both the positive-$P$ and Wigner\nrepresentations, and perform simulations to compare the predictions of the two\nmethods. The positive-$P$ approach is found to be highly susceptible to the\nstability problems that have been observed in other strongly nonlinear, weakly\ndamped systems. Using the Wigner representation, we examine the evolution of\nseveral quantities of interest using from a variety of choices of initial state\nfor the condensate, and compare results to those for single-mode models.",
        "positive": "Flexoelxctricity of the distorted twist bend nematic phase: Mesogenic dimers in the twist-bend nematic phase exhibit much higher\nflexoelectric polarization than in their uniform nematic phase. In order to\ntheoretically investigate this data, we extend the symmetry based linear\nelastic theory of the twist-bend nematic phase developed in Phys. Rev. E 92,\n030501(R) 2015, by including flexoelectricity under the action of an external\nelectric field perpendicular to the helical axis. We show that at the nematic\ntowards twist-bend nematic transition, a new flexoelectric mode becomes active.\nConsequently, the present model predicts the increase of the effective\nflexoelectric coefficient when the system is entering the twist-bend nematic\nphase. The influence of the flexoelectric coupling on the equilibrium\nwavevector and the spontaneous heliconical tilt angle are investigated. The\nelectroclinic coefficient is calculated. Finally we argue that the helix could\nbe unwound giving rise to a splay-bend nematic phase."
    },
    {
        "anchor": "A generalised lattice Boltzmann algorithm for the flow of a nematic\n  liquid crystal with variable order parameter: A lattice Boltzmann (LB) scheme is described which recovers the equations\ndeveloped by Qian--Sheng for the hydrodynamics of a nematic liquid crystal with\na tensor order parameter. The standard mesoscopic LB scalar density is\ngeneralised to a tensor quantity and the macroscopic momentum, density and\ntensor order parameter are recovered from appropriate moments of this\nmesoscopic density. A single lattice Boltzmann equation is used with a\ndirection dependent BGK collision term, with additional forcing terms to\nrecover the antisymmetric terms in the stress tensor. A Chapman Enskog analysis\nis presented which demonstrates that the Qian--Sheng scheme is recovered,\nprovided a lattice with sixth order isotropy is used. The method is validated\nagainst analytical results for a number of cases including flow alignment of\nthe order tensor and the Miesowicz viscosities in the presence of an aligning\nmagnetic field. The algorithm accurately recovers the predicted changes in the\norder parameter in the presence of aligning flow, and magnetic, fields.",
        "positive": "Reduced strength and extent of dynamic heterogeneity in a strong glass\n  former as compared to fragile glass formers: We examined dynamic heterogeneity in a model tetrahedral network\nglass-forming liquid. We used four-point correlation functions to extract\ndynamic correlation lengths xi_4^a(t) and susceptibilities chi_4^a(t)\ncorresponding to structural relaxation on two length scales a. One length scale\ncorresponds to structural relaxation at nearest neighbor distances and the\nother corresponds to relaxation of the tetrahedral structure. We find that the\ndynamic correlation length xi_4^{a} grows much slower with increasing\nrelaxation time than for model fragile glass formers. We also find that chi_4^a\n~ (xi_4^a)^z for a range of temperatures, but z < 3 at the lowest temperatures\nexamined in this study. However, we do find evidence that the temperature where\nStokes-Einstein violation begins marks a temperature where there is a change in\nthe character of dynamically heterogeneous regions. Throughout the paper, we\ncontrast the structure and dynamics of a strong glass former with that of a\nrepresentative fragile glass former."
    },
    {
        "anchor": "Enhanced Septahedral Ordering in Cold Lennard-Jones Fluids: We report molecular dynamics calculations on two-component, cold (1.2 > T >\n0.56 in natural units), three-dimensional Lennard-Jones fluids. Our system was\nsmall (7813 A, 7812 B particles), dense (N/V = 1.30), and distinctly finite (L\n\\times L \\times L cube, periodic boundary conditions, with L=22.96 \\sigma_AA),\n\\sigma_AA being the range of the $AA$ interaction in the Lennard-Jones\npotential U_{ij} = 4 \\epsilon[(\\sigma_ij/r)^12 -(\\sigma_ij/r)^6]. We calculated\nspherical harmonic components Q_LM for the density of particles in the first\ncoordination shell of each particle, as well as their spherical invariants\n<(Q_L)^2>, time-correlation functions and wavelet density decompositions. The\nspherical invariants show that non-crystalline septahedral <(Q_{7)^2> ordering\nis important, especially at low temperature. While <(Q_10)^2> could arise from\nicosahedral ordering, its behavior so closely tracks that of the nonicosahedral\n<(Q_11)^2> that alternative origins for <(Q_10)^2> need to be considered. Time\ncorrelation functions of spherical harmonic components are bimodal, with a\nfaster temperature-independent mode and a slow, strongly temperature-dependent\nmode. Microviscosities inferred from mean-square particle displacements are\nexponential in static amplitude <(Q_7)^2>, and track closely in temperature\ndependence the orientation density slow mode lifetime. Volume wavelet\ndecompositions show that when T is reduced, the correlation length of <(Q_7)^2>\nincreases, especially below T=0.7, but the correlation length of <(Q_5)^2> is\nindependent of T.",
        "positive": "Dynamic interactions between deformable drops in the Hele-Shaw geometry: A model has been developed to describe the collision and possible coalescence\nof two driven deformable drops in the Hele-Shaw cell. The interdependence\nbetween hydrodynamic effects and interfacial deformations is characterised by a\nfilm capillary number: Ca_f = (\\mu v/\\sigma)(R_o/h_o)^(3/2) as revealed by an\nanalytic perturbation solution of the governing equations for a system with\ncontinuous phase viscosity \\mu, interfacial tension \\sigma, drop radius R_o,\ncharacteristic relative velocity v and separation h_o between the drops.\nNumerical solutions of the model demonstrate the importance of the full dynamic\nhistory of the interacting drops in determining stability or coalescence. The\ngeometry of the Hele-Shaw cell allows for the possibility of using the model to\ninfer the time dependent force between colliding drops by measuring their\nseparation."
    },
    {
        "anchor": "Dynamics of Self-Threading Ring Polymers in a Gel: We study of the dynamics of ring polymers confined to diffuse in a background\ngel at low concentrations. We do this in order to probe the inter-play between\ntopology and dynamics in ring polymers. We develop an algorithm that takes into\naccount the possibility that the rings hinder their own motion by passing\nthrough themselves, i.e. \"self-threading\". Our results suggest that the number\nof self-threadings scales extensively with the length of the rings and that\nthis is substantially independent of the details of the model. The slowing down\nof the rings' dynamics is found to be related to the fraction of segments that\ncan contribute to the motion. Our results give a novel perspective on the\nmotion of ring polymers in gel, for which a complete theory is still lacking,\nand may help us to understand the irreversible trapping of ring polymers in gel\nelectrophoresis experiments.",
        "positive": "Polyelectrolyte Electrophoresis in Nanochannels: A Dissipative Particle\n  Dynamics Simulation: We present mesoscopic DPD-simulations of polyelectrolyte electrophoresis in\nconfined nanogeometries, for varying salt concentration and surface slip\nconditions. Special attention is given to the influence of electroosmotic flow\n(EOF) on the migration of the polyelectrolyte. The effective polyelectrolyte\nmobility is found to depend strongly on the boundary properties, i.e., the slip\nlength and the width of the electric double layer. Analytic expressions for the\nelectroosmotic mobility and the total mobility are derived which are in good\nagreement with the numerical results. The relevant quantity characterizing the\neffect of slippage is found to be the dimensionless quantity $\\kappa \\:\n\\delta_B$, where $\\delta_B$ is the slip length, and $\\kappa^{-1}$ an effective\nelectrostatic screening length at the channel boundaries."
    },
    {
        "anchor": "Internal noise driven generalized Langevin equation from a nonlocal\n  continuum model: Starting with a micropolar formulation, known to account for nonlocal\nmicrostructural effects at the continuum level, a generalized Langevin equation\n(GLE) for a particle, describing the predominant motion of a localized region\nthrough a single displacement degree-of-freedom (DOF), is derived. The GLE\nfeatures a memory dependent multiplicative or internal noise, which appears\nupon recognising that the micro-rotation variables possess randomness owing to\nan uncertainty principle. Unlike its classical version, the new GLE\nqualitatively reproduces the experimentally measured fluctuations in the\nsteady-state mean square displacement of scattering centers in a polyvinyl\nalcohol slab. The origin of the fluctuations is traced to nonlocal spatial\ninteractions within the continuum. A constraint equation, similar to a\nfluctuation dissipation theorem (FDT), is shown to statistically relate the\ninternal noise to the other parameters in the GLE.",
        "positive": "Shear-Induced Phase Behavior and Topological Defects in Two-Dimensional\n  Crystals: We investigate through numerical simulations how a two-dimensional crystal\nyields and flows under an applied shear. We focus over a range that allows us\nto both address the response in the limit of an infinitesimal shear rate and\ndescribe the phase behavior of the system at a finite shear rate. In doing so,\nwe carefully discuss the role of the topological defects and of the finite-size\neffects. We map out the whole phase diagram of the flowing steady state in the\nplane formed by temperature and shear rate. Shear-induced melting of the\ntwo-dimensional crystal is found to proceed in two steps: first, the solid\nloses long-range bond-orientational order and flows, even for an infinitesimal\nshear rate (in the thermodynamic limit). The resulting flowing hexatic phase\nthen melts to a flowing, rather isotropic, liquid at a finite shear rate that\ndepends on temperature. Finally, at a high shear rate, a third regime\ncorresponding to a strongly anisotropic string-like flowing phase appears."
    },
    {
        "anchor": "Tilt order parameters, polarity and inversion phenomena in smectic\n  liquid crystals: The order parameters for the phenomenological description of the smectic-{\\it\nA} to smectic-{\\it C} phase transition are formulated on the basis of molecular\nsymmetry and structure. It is shown that, unless the long molecular axis is an\naxis of two-fold or higher rotational symmetry, the ordering of the molecules\nin the smectic-{\\it C} phase gives rise to more than one tilt order parameter\nand to one or more polar order parameters. The latter describe the indigenous\npolarity of the smectic-{\\it C} phase, which is not related to molecular\nchirality but underlies the appearance of spontaneous polarisation in chiral\nsmectics. A phenomenological theory of the phase transition is formulated by\nmeans of a Landau expansion in two tilt order parameters (primary and\nsecondary) and an indigenous polarity order parameter. The coupling among these\norder parameters determines the possibility of sign inversions in the\ntemperature dependence of the spontaneous polarisation and of the helical pitch\nobserved experimentally for some chiral smectic-{\\it $C^{\\ast}$} materials. The\nmolecular interpretation of the inversion phenomena is examined in the light of\nthe new formulation.",
        "positive": "Aging and linear response in the H\u00e9braud-Lequeux model for amorphous\n  rheology: We analyse the aging dynamics of the H\\'ebraud-Lequeux model, a\nself-consistent stochastic model for the evolution of local stress in an\namorphous material. We show that the model exhibits initial-condition dependent\nfreezing: the stress diffusion constant decays with time as $D\\sim 1/t^2$\nduring aging so that the cumulative amount of memory that can be erased, which\nis given by the time integral of $D(t)$, is finite. Accordingly the shear\nstress relaxation function, which we determine in the long-time regime, only\ndecays to a plateau and becomes progressively elastic as the system ages. The\nfrequency-dependent shear modulus exhibits a corresponding overall decay of the\ndissipative part with system age, while the characteristic relaxation times\nscale linearly with age as expected."
    },
    {
        "anchor": "Shear localization in 3-Dimensional Amorphous Solids: In this paper we extend the recent theory of shear-localization in\n2-dimensional amorphous solids to 3-D. In 2-D the fundamental instability of\nshear-localization is related to the appearance of a line of displacement\nquadrupoles, that makes an angle of 45 degrees with the principal stress axis.\nIn 3-D the fundamental plastic instability is also explained by the formation\nof a lattice of anisotropic elastic inclusions. In the case of pure external\nshear stress, we demonstrate that this is a 2-dimensional triangular lattice of\nsimilar elementary events. It is shown that this lattice is arranged on a\nplane, that, similarly to the 2-D case, makes an angle of 45 degrees with\nrespect to the principal stress axis. This solution is energetically favorable\nonly if the external strain exceeds a yield-strain value, which is determined\nby the strain parameters of the elementary events and the Poisson ratio. The\npredictions of the theory are compared to numerical simulations and very good\nagreement is observed.",
        "positive": "Using the uncertainty principle to design simple interactions for\n  targeted self-assembly: We present a method that systematically simplifies isotropic interactions\ndesigned for targeted self-assembly. The uncertainty principle is used to show\nthat an optimal simplification is achieved by a combination of heat kernel\nsmoothing and Gaussian screening. We use this method to design isotropic\ninteractions for self-assembly of complex lattices and of materials with\nfunctional properties. The interactions we derive are significantly simpler\nthan those previously published, and it is realistic to discuss explicit\nexperimental implementation of the designed self-assembling components."
    },
    {
        "anchor": "Rheological similarities between dense self-propelled and sheared\n  particulate systems: Different from previous modelings of self-propelled particles, we develop a\nmethod to propel the particles with a constant average velocity instead of a\nconstant force. This constant propulsion velocity (CPV) approach is validated\nby its agreement with the conventional constant propulsion force (CPF) approach\nin the flowing regime. However, the CPV approach shows its advantage of\naccessing quasistatic flows of yield stress fluids with a vanishing propulsion\nvelocity, while the CPF approach is usually unable to because of finite system\nsize. Taking this advantage, we realize the cyclic self-propulsion and study\nthe evolution of the propulsion force with propelled particle displacement,\nboth in the quasistatic flow regime. By mapping shear stress and shear rate to\npropulsion force and propulsion velocity, we find similar rheological behaviors\nof self-propelled systems to sheared systems, including the yield force gap\nbetween the CPF and CPV approaches, propulsion force overshoot,\nreversible-irreversible transition under cyclic propulsion, and propulsion\nbands in plastic flows. These similarities suggest the underlying connections\nbetween self-propulsion and shear, although they act on systems in different\nways.",
        "positive": "Translational diffusion of a fluorescent tracer molecule in nanoconfined\n  water: Diffusion of tracer dye molecules in water confined to nanoscale is an\nimportant subject with a direct bearing on many technological applications. It\nis not yet clear however, if the dynamics of water in hydrophilic as well as\nhydrophobic nanochannels remains bulk-like. Here, we present diffusion\nmeasurement of a fluorescent dye molecule in water confined to nanoscale\nbetween two hydrophilic surfaces whose separation can be controlled with a\nprecision of less than a nm. We observe that the fluorescence intensities\ncorrelate over a fast($\\sim$ 30 $\\mu$s) and slow ($\\sim$ 1000 $\\mu$s) time\ncomponents. The slow timescale is due to adsorption of fluorophores to the\nconfining walls and it disappears in presence of 1 M salt. The fast component\nis attributed to diffusion of dye molecules in the gap and is found to be\nbulk-like for sub-10 nm separations and indicates that viscosity of water under\nconfinement remains unaltered up to confinement gap as small as $\\sim$ 5 nm.\nOur findings contradict some of the recent measurements of diffusion under\nnanoconfinement, however they are consistent with many estimates of\nself-diffusion using molecular dynamics simulations and measurements using\nneutron scattering experiments."
    },
    {
        "anchor": "The role of crosslinking density in surface stress and surface energy of\n  soft solids: Surface stress and surface energy are two fundamental parameters that\ndetermine the surface properties of any materials. While it is commonly\nbelieved that the surface stress and surface energy of liquids are identical,\nthe relationship between the two parameters in soft polymeric gels remains\ndebatable. In this work, we measured the surface stress and surface energy of\nsoft silicone gels with varying weight ratios of crosslinkers in soft wetting\nexperiments. Above a critical density, $k_0$, the surface stress was found to\nincrease significantly with crosslinking density while the surface energy\nremained unchanged. In this regime, we can estimate a non-zero surface elastic\nmodulus that also increases with the ratio of crosslinkers. By comparing the\nsurface mechanics of the soft gels with their bulk rheology, the surface\nproperties near the critical density $k_0$ were found to be closely related to\nthe underlying percolation transition of the polymer networks.",
        "positive": "Bulk modulus of soft particle assemblies under compression: Using a numerical approach based on the coupling of the discrete and finite\nelement methods, we explore the variation of the bulk modulus K of soft\nparticle assemblies undergoing isotropic compression. As the assemblies densify\nunder pressure-controlled boundary conditions, we show that the non-linearities\nof K rapidly deviate from predictions standing on a small-strain framework or\nthe Equivalent Medium Theory (EMT). Using the granular stress tensor and\nextracting the bulk properties of single representative grains under\ncompression, we propose a model to predict the evolution of K as a function of\nthe sample's solid fraction and a reference state as the applied pressure P\ntends to zero. The model closely reproduces the trends observed in our\nnumerical experiments confirming the behavior scalability of soft particle\nassemblies from the individual particle scale. Finally, we present the effect\nof the interparticle friction on K's evolution and how our model easily adapts\nto such a mechanical constraint."
    },
    {
        "anchor": "Effects of Kinks on DNA Elasticity: We study the elastic response of a worm-like polymer chain with reversible\nkink-like structural defects. This is a generic model for (a) the\ndouble-stranded DNA with sharp bends induced by binding of certain proteins,\nand (b) effects of trans-gauche rotations in the backbone of the\nsingle-stranded DNA. The problem is solved both analytically and numerically by\ngeneralizing the well-known analogy to the Quantum Rotator. In the small\nstretching force regime, we find that the persistence length is renormalized\ndue to the presence of the kinks. In the opposite regime, the response to the\nstrong stretching is determined solely by the bare persistence length with\nexponential corrections due to the ``ideal gas of kinks''. This high-force\nbehavior changes significantly in the limit of high bending rigidity of the\nchain. In that case, the leading corrections to the mechanical response are\nlikely to be due to the formation of multi-kink structures, such as kink pairs.",
        "positive": "Displacement field and elastic constants in non-ideal crystals: In this work a periodic crystal with point defects is described in the\nframework of linear response theory for broken symmetry states using\ncorrelation functions and Zwanzig-Mori equations. The main results are\nmicroscopic expressions for the elastic constants and for the coarse-grained\ndensity, point-defect density, and displacement field, which are valid in real\ncrystals, where vacancies and interstitials are present. The coarse-grained\ndensity field differs from the small wave vector limit of the microscopic\ndensity. In the long wavelength limit, we recover the phenomenological\ndescription of elasticity theory including the defect density."
    },
    {
        "anchor": "Complex Crystals from Size-disperse Spheres: Colloids are rarely perfectly uniform but follow a distribution of sizes,\nshapes, and charges. This dispersity can be inherent (static) or develop and\nchange over time (dynamic). Despite a long history of research, the conditions\nunder which non-uniform particles crystallize and which crystal forms is still\nnot well understood. Here, we demonstrate that hard spheres with Gaussian\nradius distribution and dispersity up to 19% always crystallize if compressed\nslow enough, and they do so in surprisingly complex ways. This result is\nobtained by accelerating event-driven simulations with particle swap moves for\nstatic dispersity and particle resize moves for dynamic dispersity. Above 6%\ndispersity, AB$_2$ Laves, AB$_{13}$, and a region of Frank-Kasper phases are\nfound. The Frank-Kasper region includes a quasicrystal approximant with Pearson\nsymbol oS276. Our findings are relevant for ordering phenomena in soft matter\nand alloys.",
        "positive": "Light-induced instabilities in photo-oriented liquid crystal cells: In a planar liquid crystal sample sandwiched between a photosensitive and a\nreference plate instabilities occurred, when the cell was illuminated from the\nreference side. The instabilities were induced both by polarized white light\nsource and monochromatic laser beams. Static and dynamic regimes were found;\nfor laser irradiation dynamic instability was found only in a range of\npolarization directions. A model, developed for monochromatic excitation,\npredicts that at certain thicknesses dynamic instability is forbidden.\nExperiments on a wedge-like cell confirmed this conclusion."
    },
    {
        "anchor": "Growth Shape of Isotactic Polystyrene Crystals in Thin Films: The crystal growth of isotactic polystyrene (it-PS) is investigated in very\nthin, 11 nm thick films. The it-PS crystals grown in the thin films show quite\ndifferent morphology from that in the bulk. With decreasing crystallization\ntemperature, the branching morphology in a diffusion field appears: dendrite\nand compact seaweed.\n  The branching morphology is formed through a morphological instability caused\nby the gradient of film thickness around a crystal; the thicker the film\nthickness, the larger the lateral growth rate of crystals. Regardless of the\nmorphological change, the growth rate as well as the lamellar thickness depends\non crystallization temperature as predicted by the surface kinetics.",
        "positive": "Separable Structure of Many-Body Ground-State Wave Function: We have investigated a general structure of the ground-state wave function\nfor the Schr\\\"odinger equation for $N$ identical interacting particles (bosons\nor fermions) confined in a harmonic anisotropic trap in the limit of large $N$.\nIt is shown that the ground-state wave function can be written in a separable\nform. As an example of its applications, this form is used to obtain the\nground-state wave function describing collective dynamics for $N$ trapped\nbosons interacting via contact forces."
    },
    {
        "anchor": "Structure of Quasi-One Dimensional Ribbon Colloid Suspensions: We report the results of an experimental study of a colloid fluid confined to\na quasi-one dimensional (q1D) ribbon channel as a function of channel width and\ncolloid density. Our findings confirm the principal predictions of previous\ntheoretical studies of such systems. These are (1) that the density\ndistribution of the liquid transverse to the ribbon channel exhibits\nstratification; (2) that even at the highest density the order along the\nstrata, as measured by the longitudinal pair correlation function, is\ncharacteristic of a liquid; and (3) the q1D pair correlation functions in\ndifferent strata exhibits anisotropic behavior, resembling that found in a\nMonte Carlo simulation for the in-plane pair correlation function of a hard\nsphere fluid in a planar slit.",
        "positive": "Binding and structure of tetramers in the scaling limit: The momentum-space structure of the Faddeev-Yakubovsky (FY)components of\nweakly-bound tetramers is investigated at the unitary limit using a\nrenormalized zero-range two-body interaction. The results, obtained by\nconsidering a given trimer level with binding energy $B_3$, provide further\nsupport to a universal scaling function relating the binding energies of two\nsuccessive tetramer states. The correlated scaling between the tetramer\nenergies comes from the sensitivity of the four-boson system to a short-range\nfour-body scale. Each excited $N-$th tetramer energy $B_4^{(N)}$ moves as the\nshort-range four-body scale changes, while the trimer properties are kept\nfixed, with the next excited tetramer $B_4^{(N+1)}$ emerging from the\natom-trimer threshold for a universal ratio $B_4^{(N)}/B_3 = B_4^\n{(N)}/B_4^{(N+1)} \\simeq 4.6$, which does not depend on $N$. We show that both\nchannels of the FY decomposition [atom-trimer ($K-$type) and dimer-dimer\n($H-$type)] present high momentum tails, which reflect the short-range\nfour-body scale. We also found that the $H-$channel is favored over $K-$channel\nat low momentum when the four-body momentum scale largely overcomes the\nthree-body one."
    },
    {
        "anchor": "Confined polymer nematics: order and packing in a nematic drop: We investigate the tight packing of nematic polymers inside a confining hard\nsphere. We model the polymer {\\sl via} the continuum Frank elastic free energy\naugmented by a simple density dependent part as well as by taking proper care\nof the connectivity of the polymer chains when compared with simple nematics.\nThe free energy {\\sl ansatz} is capable of describing an orientational ordering\ntransition within the sample between an isotropic polymer solution and a\npolymer nematic phase. We solve the Euler-Lagrange equations numerically with\nthe appropriate boundary conditions for the director and density field and\ninvestigate the orientation and density profile within a sphere. Two important\nparameters of the solution are the exact locations of the beginning and the end\nof the polymer chain. Pending on their spatial distribution and the actual size\nof the hard sphere enclosure we can get a plethora of various configurations of\nthe chain exhibiting different defect geometry.",
        "positive": "On the Flow Curve of Colloids Presenting Shear-Induced Phase Transitions: This work deals with the evaluation of the flow curve of colloidal systems\nthat develop fluid phases with different mechanical properties, namely\nshear-banding fluids. The problem involved is that, as different fluid phases\ncoexist in the flow domain of the rheometric cell, measured data cannot be\ndirectly converted into rheometric functions. In order to handle this problem,\na shear stress vs. shear rate constitutive relation is introduced to interpret\nthe steady state flow curves. The relation derives from a phenomenological\ndescription of structural changes, and involves the possibility of multivalued\nshear rates under a given shear stress. Numerical predictions satisfactorily\nmatch up to experimental data of wormlike micellar solutions. A crucial aspect\nis the adequate computation of the shear rate function from raw data measured\nin the rheometric cell."
    },
    {
        "anchor": "Non-Hermitian band topology and skin modes in active elastic media: Solids built out of active components can exhibit non-reciprocal elastic\ncoefficients that give rise to non-Hermitian wave phenomena. Here, we\ninvestigate non-Hermitian effects present at the boundary of two-dimensional\nactive elastic media obeying two general assumptions: their microscopic forces\nconserve linear momentum and arise only from static deformations. Using\ncontinuum equations, we demonstrate the existence of the non-Hermitian skin\neffect in which the boundary hosts an extensive number of localized modes.\nFurthermore, lattice models reveal non-Hermitian topological transitions\nmediated by exceptional rings driven by the activity level of individual bonds.",
        "positive": "Hydrodynamic crystals: collective dynamics of regular arrays of\n  spherical particles in a parallel-wall channel: Simulations of over $10^3$ hydrodynamically coupled solid spheres are\nperformed to investigate collective motion of linear trains and regular square\narrays of particles suspended in a fluid bounded by two parallel walls. Our\nnovel accelerated Stokesian-dynamics algorithm relies on simplifications\nassociated with the Hele--Shaw asymptotic far-field form of the flow scattered\nby the particles. The simulations reveal propagation of particle-displacement\nwaves, deformation and rearrangements of a particle lattice, propagation of\ndislocation defects in ordered arrays, and long-lasting coexistence of ordered\nand disordered regions."
    },
    {
        "anchor": "Nonlinear Screening and Effective Interactions in Charged Colloids: Influences of nonlinear screening on effective interactions between spherical\nmacroions in charged colloids are described via response theory. Nonlinear\nscreening, in addition to generating effective many-body interactions, is shown\nto entail essential corrections to the pair potential and one-body volume\nenergy. Numerical results demonstrate that nonlinear effects can substantially\nmodify effective interactions and thermodynamics of aqueous, low-salt\nsuspensions of highly-charged macroions.",
        "positive": "Molecular motions in glass and supercooled states of clotrimazole\n  studied by broadband dielectric spectroscopy: The molecular mobility of glassy and supercooled liquid states of\nclotrimazole is studied using broadband dielectric spectroscopy for a wide\nrange of temperatures and frequency. The dielectric loss data of clotrimazole\nbelow T$_{g}$, do not show well resolved relaxation. Above T$_{g}$, dielectric\nloss show the structural $\\alpha$-relaxation which is reformed to shoulder like\nshape at high frequencies due to the secondary relaxation. The relaxation time\nof $\\alpha$-process, $\\tau_{\\alpha}$ follows Vogel-Fulcher-Tammann equation.\nThe glass transition temperature, $T_{g}$=296K and fragility index, m=50 are\nobtained from the thermal behaviour of the $\\alpha$-process. At temperature\nnear T$_{g}$ the dielectric loss has Kohlrausch-Williams-Watts stretch\nexponential parameter $\\beta_{KWW}$=0.56. The primitive relaxation time\nobtained from the coupling model coincides with the experimentally observed\nsecondary relaxation of clotrimazole. Hence the secondary relaxation is\nconsidered to be the Johari-Goldstein (JG) process which may be the precursor\n$\\alpha$-process. The value of exponent $\\beta_{KWW}$ increases with increase\nof temperature and scaled dielectric loss do not form as single master curve.\nThe structural relaxation $\\alpha$-relaxation and JG $\\beta$-relaxation process\nand its effects in clorimazole is discussed."
    },
    {
        "anchor": "The contact mechanics challenge: Problem definition: We present a contact mechanics problem, which we consider to be\nrepresentative for contacts between nominally flat surfaces. The main\ningredients of the mathematically fully defined contact problem are:\nSelf-affine roughness, linear elasticity, the small-slope approximation, and\nshort-range adhesion between the frictionless surfaces. Surface energies,\nelastic contact modulus and computer-generated surface topographies are\nprovided at www.lms.uni-saarland.de/contact-mechanics-challenge. To minimize\nthe undesirable but frequent problem of unit conversion errors, we provide some\nbenchmark results, such as the relative contact area as a function of load\n$a_{\\rm r}(L)$ between $0.1\\%$ and $15\\%$ relative contact. We call theorists\nand numericists alike to predict quantities that contain more information than\n$a_{\\rm r}(L)$ and provide information on how to submit predictions. Examples\nfor quantities of interest are the mean gap or contact stiffness as a function\nof load as well as distributions of contact patch size, interfacial stress, and\ninterfacial separation at a reference load. Numerically accurate reference\nresults will be disseminated in subsequent work including an evaluation of the\nsubmitted results.",
        "positive": "Defect Motifs for Constant Mean Curvature Surfaces: The energy landscapes of electrostatically charged particles embedded on\nconstant mean curvature surfaces are analysed for a wide range of system size,\ncurvature, and interaction potentials. The surfaces are taken to be rigid, and\nthe basin-hopping method is used to locate the putative global minimum\nstructures. The defect motifs favoured by potential energy agree with\nexperimental observations for colloidal systems: extended defects (scars and\npleats) for weakly positive and negative Gaussian curvatures, and isolated\ndefects for strongly negative Gaussian curvatures. Near the phase boundary\nbetween these regimes the two motifs are in strong competition, as evidenced\nfrom the appearance of distinct funnels in the potential energy landscape. We\nalso report a novel defect motif consisting of pentagon pairs."
    },
    {
        "anchor": "Molecular Dynamics Simulations of Lipid Bilayers: Major Artifacts due to\n  Truncating Electrostatic Interactions: We study the influence of truncating the electrostatic interactions in a\nfully hydrated pure dipalmitoylphosphatidylcholine (DPPC) bilayer through 20 ns\nmolecular dynamics simulations. The computations in which the electrostatic\ninteractions were truncated are compared to similar simulations using the\nParticle-Mesh Ewald (PME) technique. All examined truncation distances (1.8 to\n2.5 nm) lead to major effects on the bilayer properties, such as enhanced order\nof acyl chains together with decreased areas per lipid. The results obtained\nusing PME, on the other hand, are consistent with experiments. These artifacts\nare interpreted in terms of radial distribution functions $g(r)$ of molecules\nand molecular groups in the bilayer plane. Pronounced maxima or minima in g(r)\nappear exactly at the cutoff distance indicating that the truncation gives rise\nto artificial ordering between the polar phosphatidyl and choline groups of the\nDPPC molecules. In systems described using PME, such artificial ordering is not\npresent.",
        "positive": "Adsorption of polyampholytes on charged surfaces: We have studied the adsorption of neutral polyampholytes on model charged\nsurfaces that have been characterized by contact angle and streaming current\nmeasurements. The loop size distributions of adsorbed polymer chains have been\nobtained using atomic force microscopy (AFM) and compared to recent theoretical\npredictions. We find a qualitative agreement with theory; the higher the\nsurface charge, the smaller the number of monomers in the adsorbed layer, in\nagreement with theory. We propose an original scenario for the adsorption of\npolyampholytes on surfaces covered with both neutral long-chain and charged\nshort-chain thiols."
    },
    {
        "anchor": "Janus fluid with fixed patch orientations: theory and simulations: We study thermophysical properties of a Janus fluid with constrained\norientations, using analytical techniques and numerical simulations. The Janus\ncharacter is modeled by means of a Kern-Frenkel potential where each sphere has\none hemisphere of square-well and the other of hard-sphere character. The\norientational constraint is enforced by assuming that each hemisphere can only\npoint either North or South with equal probability. The analytical approach\nhinges on a mapping of the above Janus fluid onto a binary mixture interacting\nvia a \"quasi\" isotropic potential. The anisotropic nature of the original\nKern-Frenkel potential is reflected by the asymmetry in the interactions\noccurring between the unlike components of the mixture. A rational-function\napproximation extending the corresponding symmetric case is obtained in the\nsticky limit, where the square-well becomes infinitely narrow and deep, and\nallows a fully analytical approach. Notwithstanding the rather drastic\napproximations in the analytical theory, this is shown to provide a rather\nprecise estimate of the structural and thermodynamical properties of the\noriginal Janus fluid.",
        "positive": "Polymerization dynamics of double-stranded biopolymers: chemical kinetic\n  approach: The polymerization dynamics of double-stranded polymers, such as actin\nfilaments, is investigated theoretically using simple chemical kinetic models\nthat explicitly take into account some microscopic details of the polymer\nstructure and the lateral interactions between the protofilaments. By\nconsidering all possible molecular configurations, the exact analytical\nexpressions for the growth velocity and dispersion for two-stranded polymers\nare obtained in the case of the growing at only one end, and for the growth\nfrom both polymer ends. Exact theoretical calculations are compared with the\npredictions of approximate multi-layer models that consider only a finite\nnumber of the most relevant polymer configurations. Our theoretical approach is\napplied to analyze the experimental data on the growth and fluctuations\ndynamics of individual single actin filaments."
    },
    {
        "anchor": "Tension Dynamics and Linear Viscoelastic Behavior of a Single\n  Semiflexible Polymer Chain: We study the dynamical response of a single semiflexible polymer chain based\non the theory developed by Hallatschek et al. for the wormlike-chain model. The\nlinear viscoelastic response under oscillatory forces acting at the two chain\nends is derived analytically as a function of the oscillation frequency . We\nshall show that the real part of the complex compliance in the low frequency\nlimit is consistent with the static result of Marko and Siggia whereas the\nimaginary part exhibits the power-law dependence +1/2. On the other hand, these\ncompliances decrease as the power law -7/8 for the high frequency limit. These\nare different from those of the Rouse dynamics. A scaling argument is developed\nto understand these novel results.",
        "positive": "Behaviour of the model antibody fluid constrained by rigid spherical\n  obstacles. Effects of the obstacle--antibody attraction: This study is concerned with behaviour of fluid of monoclonal antibodies\n(mAbs) when trapped in a confinement represented by rigid spherical obstacles\nthat attract proteins. The antibody molecule is depicted as an assembly of\nseven hard spheres, organized to resemble Y shaped molecule. The antibody has\ntwo Fab and one Fc domains located in the corners of letter Y. In this\ncalculation, only the Fab-Fab and Fab-Fc attractive pair interactions are\neffective. The confinement is formed by the randomly distributed hard-spheres\nfixed in space. The spherical obstacles, besides the size exclusion, also\ninteract by the Yukawa attractive interaction with with each bead of the\nantibody molecule. We applied the combination of the scaled-particle theory,\nWertheim's thermodynamic perturbation theory and the Flory-Stockmayer theory to\ncalculate: (i) the liquid-liquid phase separation, and (ii) the percolation\nthreshold. All these quantities were calculated as functions of the strength of\nthe attraction between the monoclonal antibodies, and monoclonal antibodies and\nobstacles. The conclusion is that while the hard-sphere obstacles decrease the\ncritical density as also, the critical temperature of the mAbs fluid, the\neffect of the protein-obstacle attraction is more complex. Adding the\nattraction to obstacle-mAbs interaction first increases the wideness of the\ntemperature-density envelope. However, with the further increase of the\nobstacle-mAbs attraction intensity we observe reversal of the effect, the\ntemperature-density curves become narrower. At some point, depending on the\nAC=BC interaction, the situation is observed where two different temperatures\nhave the same fluid density (reentry point ). In all the cases shown here the\ncritical point decreases below the value for the neat fluid, but the behaviour\nwith respect to increase of the strength of obstacle-mAbs attraction is not\nmonotonic."
    },
    {
        "anchor": "Asymmetric response of a jammed plastic bead raft: Fluctuation-dissipation relations have received significant attention as a\npotential method for defining an effective temperature in nonequilibrium\nsystems. The successful development of an effective temperature would be an\nimportant step in the application of statistical mechanics principles to\nsystems driven far from equilibrium. Many of the systems of interest are\nsufficiently dense that they are close to the jamming transition, a point at\nwhich interesting correlations develop. Here we study the response function in\na driven system of plastic beads as a function of the density in order to\nelucidate the impact of the jamming transition on the use of\nfluctuation-dissipation relations. The focus is on measuring the response\nfunction for applied shear stress. We find that even when the amplitude of the\napplied stress leads to a linear response in the strain, the time scale of the\nresponse is dependent on the direction of the applied stress.",
        "positive": "Swimming Euglena respond to confinement with a behavioural change\n  enabling effective crawling: Some euglenids, a family of aquatic unicellular organisms, can develop highly\nconcerted, large-amplitude peristaltic body deformations. This remarkable\nbehaviour has been known for centuries. Yet, its function remains\ncontroversial, and is even viewed as a functionless ancestral vestige. Here, by\nexamining swimming Euglena gracilis in environments of controlled crowding and\ngeometry, we show that this behaviour is triggered by confinement. Under these\nconditions, it allows cells to switch from unviable flagellar swimming to a new\nand highly robust mode of fast crawling, which can deal with extreme geometric\nconfinement and turn both frictional and hydraulic resistance into propulsive\nforces. To understand how a single cell can control such an adaptable and\nrobust mode of locomotion, we developed a computational model of the motile\napparatus of Euglena cells consisting of an active striated cell envelope. Our\nmodelling shows that gait adaptability does not require specific\nmechanosensitive feedback but instead can be explained by the mechanical\nself-regulation of an elastic and extended motor system. Our study thus\nidentifies a locomotory function and the operating principles of the adaptable\nperistaltic body deformation of Euglena cells."
    },
    {
        "anchor": "Green Algae as Model Organisms for Biological Fluid Dynamics: In the past decade the volvocine green algae, spanning from the unicellular\n$Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for\na number of problems in biological fluid dynamics. These include flagellar\npropulsion, nutrient uptake by swimming organisms, hydrodynamic interactions\nmediated by walls, collective dynamics and transport within suspensions of\nmicroswimmers, the mechanism of phototaxis, and the stochastic dynamics of\nflagellar synchronization. Green algae are well suited to the study of such\nproblems because of their range of sizes (from 10 $\\mu$m to several\nmillimetres), their geometric regularity, the ease with which they can be\ncultured and the availability of many mutants that allow for connections\nbetween molecular details and organism-level behavior. This review summarizes\nthese recent developments and highlights promising future directions in the\nstudy of biological fluid dynamics, especially in the context of evolutionary\nbiology, that can take advantage of these remarkable organisms.",
        "positive": "Strong coupling electrostatic theory of polymer counterions close to\n  planar charges: Strong coupling phenomena, such as the like charged macroions attraction,\nopposite charged macroions repulsion, charge renormalization or charge\ninversion, are known to be mediated by multivalent counterions. Most theories\ntreat the counterions as point charges, and describe the system by a single\ncoupling parameter that measures the strength of the Coulomb interactions. In\nmany biological systems, the counterions are highly charged and have finite\nsizes and can be well-described by polyelectrolytes. The shapes and\norientations of these polymer counterions play a major role in the\nthermodynamics of these systems. In this work we apply a field theoretic\ndescription in the strong coupling regime to polyelectrolytes. We work out the\nspecial cases of rod-like polymer counterions confined by one and two charged\nwalls respectively. The effects of the geometry of the rod-like counterions and\nthe excluded volume of the walls on the density, pressure and the free energy\nof the rodlike counterions are discussed."
    },
    {
        "anchor": "Predicting plastic flow events in athermal shear-strained amorphous\n  solids: We propose a method to predict the value of the external strain where a\ngeneric amorphous solid will fail by a plastic response (i.e. an irreversible\ndeformation), solely on the basis of measurements of the nonlinear elastic\nmoduli. While usually considered fundamentally different, with the elastic\nproperties describing reversible phenomena and plastic failure epitomizing\nirreversible behavior, we show that the knowledge of some nonlinear elastic\nmoduli is enough to predict where plasticity sets in.",
        "positive": "Phase Behaviour of Amphiphilic Monolayers: Theory and Simulation: Coarse grained models of monolayers of amphiphiles (Langmuir monolayers) have\nbeen studied theoretically and by computer simulations. We discuss some of the\ninsights obtained with this approach, and present new simulation results which\nshow that idealised models can successfully reproduce essential aspects of the\ngeneric phase behaviour of Langmuir monolayers."
    },
    {
        "anchor": "Data-driven criterion for the solid-liquid transition of two-dimensional\n  self-propelled colloidal particles far from equilibrium: We establish an explicit data-driven criterion for identifying the\nsolid-liquid transition of two-dimensional self-propelled colloidal particles\nin the far from equilibrium parameter regime, where the transition points\npredicted by different conventional empirical criteria for melting and freezing\ndiverge. This is achieved by applying a hybrid machine learning approach that\ncombines unsupervised learning with supervised learning to analyze over one\nmillion of the system's configurations in the nonequilibrium parameter regime.\nFurthermore, we establish a generic data-driven evaluation function, according\nto which the performance of different empirical criteria can be systematically\nevaluated and improved. In particular, by applying this evaluation function, we\nidentify a new nonequilibrium threshold value for the long-time diffusion\ncoefficient, based on which the predictions of the corresponding empirical\ncriterion are greatly improved in the far from equilibrium parameter regime.\nThese data-driven approaches provide a generic tool for investigating phase\ntransitions in complex systems where conventional empirical ones face\ndifficulties.",
        "positive": "Spatial Distributions of Local Elastic Moduli Near the Jamming\n  Transition: Recent progress on studies of the nanoscale mechanical responses in\ndisordered systems has highlighted a strong degree of heterogeneity in the\nelastic moduli. In this contribution, using computer simulations, we study the\nelastic heterogeneities in athermal amorphous solids, composed of isotropic,\nstatic, sphere packings, near the jamming transition. We employ techniques,\nbased on linear response methods, that are amenable to experimentation. We find\nthat the local elastic moduli are randomly distributed in space and are\ndescribed by Gaussian probability distributions, thereby lacking any\nsignificant spatial correlations, that persists all the way down to the\ntransition point. However, the shear modulus fluctuations grow as the jamming\nthreshold is approached, which is characterized by a new power-law scaling.\nThrough this diverging behavior we are able to identify a characteristic length\nscale, associated with shear modulus heterogeneities, that distinguishes\nbetween bulk and local elastic responses."
    },
    {
        "anchor": "On the Nature of Freezing/Melting Water in Ionic Polysulfones: We investigate the behavior of hydrated sulfonated polysulfones over a range\nof ion contents through differential scanning calorimetry (DSC), Fourier\ntransform infrared spectroscopy (FTIR), and molecular dynamics (MD)\nsimulations. Experimental evidence shows that at comparable ion contents, the\nspacing between the ionic groups along the polymer backbone can significantly\nimpact the amount of melting water present in the polymer. When we only\nconsider water molecules that can hydrogen bond to four neighboring water\nmolecules as the melting water, the MD simulation results are found to agree\nwith the experimental data. The states of water measured by DSC can therefore\nbe described as \"aggregated\" (or bulk-like) for the melting component, and\n\"isolated\" for the nonmelting part. Using this physical picture, a polymer with\nmore aggregated ions has a higher content of melting water, while a polymer at\nthe same ion content but with more dispersed ions has a lower content of\nmelting water. Therefore, ions should be well dispersed to minimize the amount\nof bulk-like water in ionic polymer membranes.",
        "positive": "Robophysical study of jumping dynamics on granular media: Characterizing forces on deformable objects intruding into sand and soil\nrequires understanding the solid and fluid-like responses of such substrates\nand their effect on the state of the object. The most detailed studies of\nintrusion in dry granular media have revealed that interactions of fixed-shape\nobjects during free impact (e.g. cannonballs) and forced slow penetration can\nbe described by hydrostatic and hydrodynamic-like forces. Here we investigate a\nnew class of granular interactions: rapid intrusions by objects that change\nshape (self-deform) through passive and active means. Systematic studies of a\nsimple spring-mass robot jumping on dry granular media reveal that jumping\nperformance is explained by an interplay of nonlinear frictional and\nhydrodynamic drag as well as induced added mass (unaccounted by traditional\nintrusion models) characterized by a rapidly solidified region of grains\naccelerated by the foot. A model incorporating these dynamics reveals that\nadded mass degrades the performance of certain self-deformations due to a shift\nin optimal timing during push-off. Our systematic robophysical experiment\nreveals both new soft matter physics and principles for robotic\nself-deformation and control, which together provide principles of movement in\ndeformable terrestrial environments."
    },
    {
        "anchor": "Fluid phase separation inside a static periodic field: an effectively\n  two-dimensional critical phenomenon: When a fluid with a bulk liquid-vapor critical point is placed inside a\nstatic external field with spatial periodic oscillations in one direction, the\nbulk critical point splits into two new critical points and a triple point.\nThis phenomenon is called laser-induced condensation [Mol. Phys. Vol. 101, Pg.\n1651 (2003)], and it occurs when the wavelength of the field is sufficiently\nlarge. The critical points mark the end of two coexistence regions, namely\nbetween (1) a vapor and stacked-fluid phase, and (2) a stacked-fluid and liquid\nphase. The stacked-fluid or \"zebra\" phase is characterized by large density\noscillations along the field direction. We study the above phenomenon for a\nmixture of colloids and polymers using density functional theory and computer\nsimulation. The theory predicts that the vapor-zebra and liquid-zebra surface\ntensions are extremely small. Most strikingly, however, is the theoretical\nfinding that at their respective critical points, both tensions vanish, but not\naccording to any critical power law. The solution to this apparent paradox is\nprovided by the simulations. These show that the field divides the system into\neffectively two-dimensional slabs, stacked on top of each other along the field\ndirection. Inside each slab, the system behaves as if it were two-dimensional,\nwhile in the field direction the system resembles a one-dimensional Ising\nchain.",
        "positive": "Soft hydraulics: from Newtonian to complex fluid flows through compliant\n  conduits: Microfluidic devices manufactured from soft polymeric materials have emerged\nas a paradigm for cheap, disposable and easy-to-prototype fluidic platforms for\nintegrating chemical and biological assays and analyses. The interplay between\nthe flow forces and the inherently compliant conduits of such microfluidic\ndevices requires careful consideration. While mechanical compliance was\ninitially a side-effect of the manufacturing process and materials used,\ncompliance has now become a paradigm, enabling new approaches to\nmicrorheological measurements, new modalities of micromixing, and improved\nsieving of micro- and nano-particles, to name a few applications. This topical\nreview provides an introduction to the physics of these systems. Specifically,\nthe goal of this review is to summarize the recent progress towards a\nmechanistic understanding of the interaction between non-Newtonian (complex)\nfluid flows and their deformable confining boundaries. In this context, key\nexperimental results and relevant applications are also explored, hand-in-hand\nwith the fundamental principles for their physics-based modeling. The key\ntopics covered include shear-dependent viscosity of non-Newtonian fluids,\nhydrodynamic pressure gradients during flow, the elastic response (deformation\nand bulging) of soft conduits due to flow within, the effect of cross-sectional\nconduit geometry on the resulting fluid--structure interaction, and key\ndimensionless groups describing the coupled physics. Open problems and future\ndirections in this nascent field of soft hydraulics, at the intersection of\nnon-Newtonian fluid mechanics, soft matter physics, and microfluidics, are\nnoted."
    },
    {
        "anchor": "Chemical potential of a test hard sphere of variable size in hard-sphere\n  fluid mixtures: A detailed comparison between the Boubl\\'ik-Mansoori-Carnahan-Starling-Leland\n(BMCSL)equation of state of hard-sphere mixtures is made with Molecular\nDynamics (MD) simulations of the same compositions. The Lab\\'ik and Smith\nsimulation technique [S. Lab\\'ik and W. R. Smith, Mol. Simul. \\textbf{12},\n23-31 (1994)] was used to implement the Widom particle insertion method to\ncalculate the excess chemical potential, $\\beta \\mu_0^\\text{ex}$, of a test\nparticle of variable diameter, $\\sigma_0$, immersed in a hard-sphere fluid\nmixture with different compositions and values of the packing fraction, $\\eta$.\nUse is made of the fact that the only polynomial representation of $\\beta\n\\mu_0^\\text{ex}$ which is consistent with the limits $\\sigma_0\\to 0$ and\n$\\sigma_0\\to\\infty$ has to be of the cubic form, i.e.,\n$c_0(\\eta)+\\overline{c}_1(\\eta)\\sigma_0/M_{1}+\\overline{c}_2(\\eta)(\\sigma_0/M_{1})^2+\\overline{c}_3(\\eta)(\\sigma_0/M_{1})^3$,\nwhere $M_{1}$ is the first moment of the distribution. The first two\ncoefficients, $c_0(\\eta)$ and $\\overline{c}_1(\\eta)$, are known analytically,\nwhile $\\overline{c}_2(\\eta)$ and $\\overline{c}_3(\\eta)$ were obtained by\nfitting the MD data to this expression. This in turn provides a method to\ndetermine the excess free energy per particle, $\\beta a^\\text{ex}$, in terms of\n$\\overline{c}_2$, $\\overline{c}_3$, and the compressibility factor, $Z$. Very\ngood agreement between the BMCSL formulas and the MD data is found for $\\beta\n\\mu^\\text{ex}_0$, $Z$, and $\\beta a^\\text{ex}$ for binary mixtures and\ncontinuous particle size distributions with the top-hat analytic form. However,\nthe BMCSL theory typically slightly underestimates the simulation values,\nespecially for $Z$, differences which the Boubl\\'ik-Carnahan-Starling-Kolafa\nformulas and an interpolation between two Percus-Yevick routes capture well in\ndifferent ranges of the system parameter space.",
        "positive": "Sound-mediated dynamic correlations between colloidal particles in a\n  quasi-one-dimensional channel: We study the hydrodynamic interactions between colloids suspended in a\ncompressible fluid inside a rigid channel. Using lattice-Boltzmann simulations\nand a simplified hydrodynamic theory, we find that the diffusive dynamics of\ndensity perturbations (sound) in the confined fluid give rise to particle\ncorrelations of exceptionally long spatial range and algebraic temporal decay.\nWe examine the effect of these sound-mediated correlations on two-particle\ndynamics and on the collective dynamics of a quasi-one-dimensional suspension."
    },
    {
        "anchor": "Assembly of particle strings via isotropic potentials: Assembly of spherical colloidal particles into extended structures, including\nlinear strings, in the absence of directional interparticle bonding\ninteractions or external perturbation could facilitate the design of new\nfunctional materials. Here, we use methods of inverse design to discover\nisotropic pair potentials that promote the formation of single-stranded,\npolydisperse strings of colloids \"colloidomers\" as well as size-specific,\ncompact colloidal clusters. Based on the designed potentials, a simple model\npair interaction with a short-range attraction and a longer-range repulsion is\nproposed which stabilizes a variety of different particle morphologies\nincluding (i) dispersed fluid of monomers, (ii) ergodic short particle chains\nas well as porous networks of percolated strings, (iii) compact clusters, and\n(iv) thick cylindrical structures including trihelical Bernal spirals.",
        "positive": "Nematic and Polar order in Active Filament Solutions: Using a microscopic model of interacting polar biofilaments and motor\nproteins, we characterize the phase diagram of both homogeneous and\ninhomogeneous states in terms of experimental parameters. The polarity of motor\nclusters is key in determining the organization of the filaments in homogeneous\nisotropic, polarized and nematic states, while motor-induced bundling yields\nspatially inhomogeneous structures."
    },
    {
        "anchor": "Contact statistics highlight distinct organizing principles of proteins\n  and RNA: Although both RNA and proteins have densely packed native structures, chain\norganizations of these two biopolymers are fundamentally different. Motivated\nby the recent discoveries in chromatin folding that interphase chromosomes have\nterritorial organization with signatures pointing to metastability, we analyzed\nthe biomolecular structures deposited in the Protein Data Bank and found that\nthe intrachain contact probabilities, $P(s)$ as a function of the arc length\n$s$, decay in power-law $\\sim s^{-\\gamma}$ over the intermediate range of $s$,\n$10\\lesssim s\\lesssim 110$. We found that the contact probability scaling\nexponent is $\\gamma\\approx 1.11$ for large RNA ($N>110$), $\\gamma\\approx 1.41$\nfor small sized RNA ($N<110$), and $\\gamma\\approx 1.65$ for proteins. Given\nthat Gaussian statistics is expected for a fully equilibrated chain in polymer\nmelts, the deviation of $\\gamma$ value from $\\gamma=1.5$ for the subchains of\nlarge RNA in the native state suggests that the chain configuration of RNA is\nnot fully equilibrated. It is visually clear that folded structures of large\nsized RNA ($N\\gtrsim 110$) adopt crumpled structures, partitioned into modular\nmulti-domains assembled by proximal sequences along the chain, whereas the\npolypeptide chain of folded proteins looks better mixed with the rest of the\nstructure. Our finding of $\\gamma\\approx 1$ for large RNA might be an\nineluctable consequence of the hierarchical ordering of the secondary to\ntertiary elements in the folding process.",
        "positive": "Cluster structure and dynamics in gels and glasses: The dynamical arrest of gels is the consequence of a well defined structural\nphase transition, leading to the formation of a spanning cluster of bonded\nparticles. The dynamical glass transition, instead, is not accompanied by any\nclear structural signature. Nevertheless, both transitions are characterized by\nthe emergence of dynamical heterogeneities. Reviewing recent results from\nnumerical simulations, we discuss the behavior of dynamical heterogeneities in\ndifferent systems and show that a clear connection with the structure exists in\nthe case of gels. The emerging picture may be also relevant for the more\nelusive case of glasses. We show, as an example, that the relaxation process of\na simple glass-forming model can be related to a reverse percolation transition\nand discuss further perspective in this direction."
    },
    {
        "anchor": "Comparison of Conformational Phase Behavior for Flexible and\n  Semiflexible Polymers: We employ the recently introduced generalized microcanonical inflection point\nmethod for the statistical analysis of phase transitions in flexible and\nsemiflexible polymers and study the impact of the bending stiffness upon the\ncharacter and order of transitions between random-coil, globules, and\npseudocrystalline conformations. The high-accuracy estimates of the\nmicrocanonical entropy and its derivatives required for this study were\nobtained by extensive replica-exchange Monte Carlo simulations. We observe that\nthe transition behavior into the compact phases changes qualitatively with\nincreasing bending stiffness. Whereas the $\\Theta$ collapse transition is less\naffected, the first-order liquid-solid transition characteristic for flexible\npolymers ceases to exist once bending effects dominate over attractive\nmonomer-monomer interactions.",
        "positive": "Undulation Amplitude of a Fluid Membrane Surrounded by Near-Critical\n  Binary Fluid Mixtures: We consider the thermal undulation, or shape fluctuation, of an almost planar\nfluid membrane surrounded by the same near-critical binary fluid mixtures on\nboth sides. A weak preferential attraction is assumed between the membrane and\none component of the mixture. We use the Gaussian free-energy functional to\nstudy the equilibrium average of the undulation amplitude within the linear\napproximation with respect to the amplitude. According to our result given by a\nsimple analytic formula, the ambient near-criticality tends to suppress the\nundulation of a membrane, and this suppression effect can overwhelm that of the\nbending rigidity for small wave numbers. Thus, the ambient near-criticality is\nsuggested to prevent a large membrane from becoming floppy even if the lateral\ntension vanishes at the equilibrium."
    },
    {
        "anchor": "Antinematic local order in dendrimer liquids: We use monomer-resolved numerical simulations to study the positional and\norientational structure of a dense dendrimer solution, focusing on the effects\nof dendrimers' prolate shape and deformability on the short-range order. Our\nresults provide unambiguous evidence that the nearest-neighbor shell of a\ntagged particle consists of a mixture of crossed, side-by-side, side-to-end,\nand end-to-end pair configurations, imposing antinematic rather than nematic\norder observed in undeformable rodlike particles. This packing pattern persists\neven at densities where particle overlap becomes sizable. We demonstrate that\nthe antinematic arrangement is compatible with the A15 crystal lattice reported\nin several dendrimer compounds.",
        "positive": "Velocity Force Curves, Laning, and Jamming for Oppositely Driven Disk\n  Systems: Using simulations we examine a two-dimensional disk system in which two disk\nspecies are driven in opposite directions. We measure the average velocity of\none of the species versus the applied driving force and identify four phases as\nfunction of drive and disk density: a jammed state, a completely phase\nseparated state, a continuously mixing phase, and a laning phase. The\ntransitions between these phases are correlated with jumps in the\nvelocity-force curves that are similar to the behavior observed at dynamical\nphase transitions in driven particle systems with quenched disorder such as\nvortices in type-II superconductors. In some cases the transitions between\nphases are associated with negative differential mobility in which the average\nabsolute velocity of either species decreases with increasing drive. We also\nconsider the situation where the drive is applied to only one species as well\nas systems in which both species are driven in the same direction with\ndifferent drive amplitudes. Finally, we discuss how the transitions we observe\ncould be related to absorbing phase transitions where a system in a phase\nseparated or laning regime organizes to a state in which contacts between the\ndisks no longer occur and dynamical fluctuations are lost."
    },
    {
        "anchor": "Strong-coupling theory of counterions with hard cores between\n  symmetrically charged walls: By a combination of Monte Carlo simulations and analytical calculations, we\ninvestigate the effective interactions between highly charged planar\ninterfaces, neutralized by mobile counterions (salt-free system). While most\nprevious analysis have focused on point-like counterions, we treat them as\ncharged hard spheres. We thus work out the fate of like-charge attraction when\nsteric effects are at work. The analytical approach partitions counterions in\ntwo sub-populations, one for each plate, and integrates out one sub-population\nto derive an effective Hamiltonian for the remaining one. The effective\nHamiltonian features plaquette four-particle interactions, and it is worked out\nby computing a Gibbs-Bogoliubov inequality for the free energy. At the root of\nthe treatment is the fact that under strong electrostatic coupling, the system\nof charges forms an ordered arrangement, that can be affected by steric\ninteractions. Fluctuations around the reference positions are accounted for. To\ndominant order at high coupling, it is found that steric effects do not\nsignificantly affect the interplate effective pressure, apart at small\ndistances where hard sphere overlap are unavoidable, and thus rule out\nconfigurations.",
        "positive": "The Immunity of Polymer-Microemulsion Networks: The concept of network immunity, i.e., the robustness of the network\nconnectivity after a random deletion of edges or vertices, has been\ninvestigated in biological or communication networks. We apply this concept to\na self-assembling, physical network of microemulsion droplets connected by\ntelechelic polymers, where more than one polymer can connect a pair of\ndroplets. The gel phase of this system has higher immunity if it is more likely\nto survive (i.e., maintain a macroscopic, connected component) when some of the\npolymers are randomly degraded. We consider the distribution $p(\\sigma)$ of the\nnumber of polymers between a pair of droplets, and show that gel immunity\ndecreases as the variance of $p(\\sigma)$ increases. Repulsive interactions\nbetween the polymers decrease the variance, while attractive interactions\nincrease the variance, and may result in a bimodal $p(\\sigma)$."
    },
    {
        "anchor": "Do hierarchical structures assemble best via hierarchical pathways?: Hierarchically structured natural materials possess functionalities\nunattainable to the same components organized or mixed in simpler ways. For\ninstance, the bones and teeth of mammals are far stronger and more durable than\nthe mineral phases from which they are derived because their constituents are\norganized hierarchically from the molecular scale to the macroscale. Making\nsimilarly functional synthetic hierarchical materials will require an\nunderstanding of how to promote the self-assembly of structure on multiple\nlengthscales, without falling foul of numerous possible kinetic traps. Here we\nuse computer simulation to study the self-assembly of a simple hierarchical\nstructure, a square crystal lattice whose repeat unit is a tetramer. Although\nthe target material is organized hierarchically, it self-assembles most\nreliably when its dynamic assembly pathway consists of the sequential addition\nof monomers to a single structure. Hierarchical dynamic pathways via dimer and\ntetramer intermediates are also viable modes of assembly, but result in general\nin lower yield: these intermediates have a stronger tendency than monomers to\nassociate in ways not compatible with the target structure. In addition,\nassembly via tetramers results in a kinetic trap whereby material is\nsequestered in trimers that cannot combine to form the target crystal. We use\nanalytic theory to relate dynamical pathways to the presence of equilibrium\nphases close in free energy to the target structure, and to identify the\nthermodynamic principles underpinning optimum self-assembly in this model: 1)\nmake the free energy gap between the target phase and the most stable fluid\nphase of order kT, and 2) ensure that no other dense phases (liquids or\nclose-packed solids of monomers or oligomers) or fluids of incomplete building\nblocks fall within this gap.",
        "positive": "SiMPLISTIC: A Novel Pairwise Potential for Implicit Solvent Lipid\n  Simulations with Single-site Models: Implicit solvent, coarse-grained models with pairwise interactions can access\nthe largest length and time scales in molecular dynamics simulations, owing to\nthe absence of interactions with a huge number of solvent particles, the\nsmaller number of interaction sites in the model molecules, and the lack of\nfast sub-molecular degrees of freedom. In this paper, we describe a maximally\ncoarse-grained model for lipids in implicit water. The model is called\nSiMPLISTIC, which abbreviates for Single-site Model with Pairwise interaction\nfor Lipids in Implicit Solvent with Tuneable Intrinsic Curvature. SiMPLISTIC\nlipids rapidly self-assemble into realistic non-lamellar and lamellar phases\nsuch as inverted micelles and bilayers, the spontaneous curvature of the phase\nbeing determined by a single free parameter of the model. Model membrane\nsimulations with the lamellar lipids show satisfactory fluid and gel phases\nwith no interdigitation or tilt. The model lipids follow rigid body dynamics\nsuggested by empirical studies, and generate bilayer elastic properties\nconsistent with experiments and other simulations. SiMPLISTIC can also simulate\nmixtures of lipids that differ in their packing parameter or length, the latter\nleading to the phenomenon of hydrophobic mismatch driven domain formation. The\nmodel has a large scope due to its speed, conceptual and computational\nsimplicity, and versatility. Applications may range from large-scale\nsimulations for academic and industrial research on various lipid-based\nsystems, such as lyotropic liquid crystals, biological and biomimetic\nmembranes, vectors for drug and gene delivery, to fast, lightweight,\ninteractive simulations for gaining insights into self-assembly, lipid\npolymorphism, biomembrane organization etc."
    },
    {
        "anchor": "Active Microrheology of Driven Granular Particles: When pulling a particle in a driven granular fluid with constant force\n$F_{ex}$, the probe particle approaches a steady-state average velocity $v$.\nThis velocity and the corresponding friction coefficient of the probe\n$\\zeta=F_{ex}/v$ are obtained within a schematic model of mode-coupling theory\nand compared to results from event-driven simulations. For small and moderate\ndrag forces, the model describes the simulation results successfully for both\nthe linear as well as the nonlinear region: The linear response regime\n(constant friction) for small drag forces is followed by shear thinning\n(decreasing friction) for moderate forces. For large forces, the model\ndemonstrates a subsequent increasing friction in qualitative agreement with the\ndata. The square-root increase of the friction with force found in [Fiege et\nal., Granular Matter $\\boldsymbol{14}$, 247 (2012)] is explained by a simple\nkinetic theory.",
        "positive": "Subdiffusive model of substance releasing from a thick membrane: We study both theoretically and experimentally the process of subdiffusive\nsubstance releasing from a thick membrane. The theoretical model uses the\nsubdiffusion equation with fractional time derivative and specific boundary\nconditions at the membrane surfaces. Using a special \\textit{ansatz} we find\nanalytical formulas describing the time evolution of concentration profiles and\nan amount of the substance remains in the membrane. Fitting the theoretical\nfunctions to the experimental results, we estimate the subdiffusion coefficient\nof polyethylene glycol 2000 in agarose hydrogel."
    },
    {
        "anchor": "Transport coefficients of dissipative particle dynamics with finite time\n  step: The viscosity and self-diffusion constant of a mesoscale hydrodynamic method,\ndissipative particle dynamics (DPD), are investigated. The viscosity of DPD\nwith finite time step, including the Lowe-Anderson thermostat, is derived\nanalytically for the ideal-gas equation of state and phenomenologically for\nsystems with soft repulsive potentials. The results agree well with numerical\ndata. The scaling of the local relative velocity in molecular dynamics\nsimulations is shown to be useful to obtain faster diffusion than for the DPD\nthermostat.",
        "positive": "Average cluster size inside sediment left after droplet desiccation: In this work, we continue to study the formation of particle chains\n(clusters) inside the annular sediment during the drying of a colloidal droplet\non a substrate. The average value of the cluster size was determined after\nprocessing experimental data from other authors. We performed a series of\ncalculations and found the value of the model parameter allowed to get\nnumerical results agreed with the experiment. Also, a modification of the\npreviously proposed algorithm is analyzed here."
    },
    {
        "anchor": "Triangle-Well and Ramp Interactions in One-Dimensional Fluids: A Fully\n  Analytic Exact Solution: The exact statistical-mechanical solution for the equilibrium properties,\nboth thermodynamic and structural, of one-dimensional fluids of particles\ninteracting via the triangle-well and the ramp potentials is worked out. In\ncontrast to previous studies, where the radial distribution function $g(r)$ was\nobtained numerically from the structure factor by Fourier inversion, we provide\na fully analytic representation of $g(r)$ up to any desired distance. The\nsolution is employed to perform an extensive study of the equation of state,\nthe excess internal energy per particle, the residual multiparticle entropy,\nthe structure factor, the radial distribution function, and the direct\ncorrelation function. In addition, scatter plots of the bridge function versus\nthe indirect correlation function are used to gauge the reliability of the\nhypernetted-chain, Percus--Yevick, and Martynov--Sarkisov closures. Finally,\nthe Fisher--Widom and Widom lines are obtained in the case of the triangle-well\nmodel.",
        "positive": "Particle Density Distributions in Fermi Gas Superfluids: Molecular Boson\n  Effects: We show how to describe the $T \\neq 0$ behavior associated with the usual\nBCS- Bose Einstein condensation (BEC) crossover ground state. We confine our\nattention here to the BEC and near-BEC regime where analytical calculations are\npossible. At finite $T$, non-condensed fermion pairs must be included, although\nthey have been generally ignored in the literature. Within this BEC regime we\ncompute the equations of state for the one and two channel models; these two\ncases correspond to whether Feshbach resonance effects are omitted or included.\nDifferences between these two cases can be traced to differences between the\nnature of a Cooper pair and bosonic condensate. Our results are also compared\nwith the Gross Pitaevskii equations of state for true bosons. Differences found\nhere are associated with the underlying fermionic character of the system.\nFinally, the particle density distribution functions for a trap containing\nsuperfluid fermionic atoms are computed using a Thomas-Fermi approach. The one\nand two channel behavior is found to be very different; we find a narrowing of\nthe density profile as a result of Feshbach resonance effects. Importantly, we\ninfer that the ratio between bosonic and fermionic scattering lengths depends\non the magnetic detuning and is generally smaller than 2. Future experiments\nwill be required to determine to what extent this ratio varies with magnetic\nfields."
    },
    {
        "anchor": "Friction and Adhesion mediated by supramolecular host-guest complexes: The adhesive and frictional response of an AFM tip connected to a substrate\nthrough supramolecular host-guest complexes is investigated by dynamic Monte\nCarlo simulations. The variation of the pull-off force with the unloading rate\nrecently observed in experiments is here unraveled by evidencing a simultaneous\n(progressive) break of the bonds at fast (slow) rates. The model reveals the\norigin of the observed plateaus in the retraction force as a function of\ntip-surface distance, showing that they ensue from the tip geometrical\nfeatures. In lateral sliding, the model exhibits a wide range of dynamic\nbehaviors ranging from smooth sliding to stick-slip at different velocities,\nwith the average friction force determined by the characteristic\nformation/rupture rates of the complexes. In particular, it is shown that for\nsome molecular complexes friction can become almost constant over a wide range\nof velocities. Also, we show the possibility to exploit ageing effect through\nslide-hold-slide experiments, in order to infer the characteristic formation\nrate. Finally, our model predicts a novel \"anti-ageing\" effect which is\ncharacterized by a decrease of static friction force with the hold time. Such\neffect is explained in terms of enhancement of adhesion during sliding,\nespecially observed at high driving velocities.",
        "positive": "Can re-entrance be observed in force induced transitions?: A large conformational change in the reaction co-ordinate and the role of the\nsolvent in the formation of base-pairing are combined to settle a long standing\nissue {\\it i.e.} prediction of re-entrance in the force induced transition of\nDNA. A direct way to observe the re-entrance, i.e a strand goes to the closed\nstate from the open state and again to the open state with temperature, appears\ndifficult to be achieved in the laboratory. An experimental protocol (in direct\nway) in the constant force ensemble is being proposed for the first time that\nwill enable the observation of the re-entrance behavior in the\nforce-temperature plane. Our exact results for small oligonucleotide that forms\na hairpin structure provide the evidence that re-entrance can be observed."
    },
    {
        "anchor": "Testing the Foundations of Classical Entropy: Colloid Experiments: Defining the entropy of classical particles raises a number of paradoxes and\nambiguities, some of which have been known for over a century. Several, such as\nGibbs' paradox, involve the fact that classical particles are distinguishable,\nand in textbooks these are often `resolved' by appeal to the quantum-mechanical\nindistinguishability of atoms or molecules of the same type. However, questions\nthen remain of how to correctly define the entropy of large poly-atomic\nparticles such as colloids in suspension, of which no two are exactly alike. By\nperforming experiments on such colloids, one can establish that certain\ndefinitions of the classical entropy fit the data, while others in the\nliterature do not. Specifically, the experimental facts point firmly to an\n`informatic' interpretation that dates back to Gibbs: entropy is determined by\nthe number of microstates that we as observers choose to treat as equivalent\nwhen we identify a macrostate. This approach, unlike some others, can account\nfor the existence of colloidal crystals, and for the observed abundances of\ncolloidal clusters of different shapes. We also address some lesser-known\nparadoxes whereby the physics of colloidal assemblies, which ought to be purely\nclassical, seems to involve quantum mechanics directly. The experimental\nsymptoms of such involvement are predicted to be `isotope effects' in which\ncolloids with different inertial masses, but otherwise identical sizes and\nproperties, show different aggregation statistics. These paradoxes are caused\nby focussing one's attention on some classical degrees while neglecting others;\nwhen all are treated equally, all isotope effects are found to vanish.",
        "positive": "Tuning thermal transport in highly cross-linked polymers by bond induced\n  void engineering: Tuning the heat flow is fundamentally important for the design of advanced\nfunctional materials. Here, polymers are of particular importance because they\nprovide different pathways for the energy transfer. More specifically, the heat\nflow between two covalently bonded monomers is over 100 times faster than\nbetween the two non-bonded monomers interacting via van der Waals (vdW) forces.\nTherefore, the delicate balance between these two contributions often provide a\nguiding tool for the tunability in thermal transport coefficient k of the\npolymeric materials. Traditionally most studies have investigated k in the\nlinear polymeric materials, the recent interests have also been directed\ntowards the highly cross-linked polymers (HCP). In this work, using the generic\nmolecular dynamics simulations we investigate the factors effecting k of HCP.\nWe emphasize on the importance of the cross-linking bond types and its\ninfluence on the network microstructure with a goal to provide a guiding\nprinciple for the tunability in k. While these simulation results are discussed\nin the context of the available experimental data, we also make predictions."
    },
    {
        "anchor": "New Field Model of Polymer/Nanoparticle Mixture-Realizing Discreteness\n  in the Continuous Description: Field-theoretical method is efficient in predicting the assembling structures\nof polymeric systems. However, for the polymer/nanoparticle mixture, the\ncontinuous density description is not suitable to capture the realistic\nassembly of particles, especially when the size of particle is much larger than\nthe polymer segment. Here, we developed a field-based model, in which the\nparticles are eventually discrete and hence it can overcome the drawbacks of\nthe conventional field descriptions, e.g., inadequate and crude treatment on\nthe polymer-particle interface and the excluded-volume interaction. We applied\nthe model to study the simplest system of nanoparticles immersed in dense\nhomopolymer solution. Our model can address the depletion effect and\ninterfacial interaction in a more delicate way. Insights into the enthalpic\nand/or entropic origin of the structural variation due to the competition\nbetween depletion and interfacial interaction are obtained. New phenomena such\nas depletion-enhanced bridging aggregation are observed in the case of strong\ninterfacial attraction and large depletion length. This approach is readily\nextendable to studying more complex polymer-based nanocomposites or\nbiology-related systems, such as dendrimer/drug encapsulation and\nmembrane/particle assembly.",
        "positive": "Regimes of wrinkling in an indented floating elastic sheet: A thin, elastic sheet floating on the surface of a liquid bath wrinkles when\npoked at its centre. We study the onset of wrinkling as well as the evolution\nof the pattern as indentation progresses far beyond the wrinkling threshold. We\nuse tension field theory to describe the macroscopic properties of the deformed\nfilm and show that the system passes through a host of different regimes, even\nwhile the deflections and strains remain small. We show that the effect of the\nfinite size of the sheet ultimately plays a key role in determining the\nlocation of the wrinkle pattern, and obtain scaling relations that characterize\nthe number of wrinkles at threshold and its variation as the indentation\nprogresses. Some of our predictions are confirmed by recent experiments of Ripp\n\\emph{et al.} [arxiv: 1804.02421]."
    },
    {
        "anchor": "A bending fluctuation-based mechanism for particle detection by ciliated\n  structures: To mimic the mechanical response of passive biological cilia in complex\nfluids, we study the bending dynamics of an anchored elastic fiber submitted to\na dilute granular suspension under shear. We show that the bending fluctuations\nof the fiber accurately encode minute variations of the granular suspension\nconcentration. Indeed, besides the stationary bending induced by the continuous\nphase flow, the passage of each single particle induces an additional\ndeflection. We demonstrate that the dominant particle/fiber interaction arises\nfrom direct contacts of the particles with the fiber and we propose a simple\nelastohydrodynamics model to predict their amplitude. Our results shed light on\nthe extreme mechanical sensitivity of biological cilia to detect the presence\nof solid particles in their vicinity and bring a physical framework to describe\ntheir dynamics in particulate flows.",
        "positive": "Specific properties of supercooled water in light of water anomalies: We review the effect of water anomalies on the properties of low temperature\nwater. When supercooled, liquids dynamical properties change drastically.\nSupercooled liquids undergo an at least exponential decrease of their diffusion\ncoefficient when temperature decreases while their structure merely does not\nchange. We discuss how that still unexplained change of dynamical properties at\nlow temperatures affect water differently from other liquids and what can be\ndeduced from it."
    },
    {
        "anchor": "Tuning the motility and directionality of self-propelled colloids: Microorganisms are able to overcome the thermal randomness of their\nsurroundings by harvesting energy to navigate in viscous fluid environments. In\na similar manner, synthetic colloidal microswimmers are capable of mimicking\ncomplex biolocomotion by means of simple self-propulsion mechanisms. Although\nexperimentally the speed of active particles can be controlled by e.g.\nself-generated chemical and thermal gradients, an in-situ change of swimming\ndirection remains a challenge. In this work, we study self-propulsion of\nhalf-coated spherical colloids in critical binary mixtures and show that the\ncoupling of local body forces, induced by laser illumination, and the wetting\nproperties of the colloid, can be used to finely tune both the colloid's\nswimming speed and its directionality. We experimentally and numerically\ndemonstrate that the direction of motion can be reversibly switched by means of\nthe size and shape of the droplet(s) nucleated around the colloid, depending on\nthe particle radius and the fluid's ambient temperature. Moreover, the\naforementioned features enable the possibility to realize both negative and\npositive phototaxis in light intensity gradients. Our results can be extended\nto other types of half-coated microswimmers, provided that both of their\nhemispheres are selectively made active but with distinct physical properties.",
        "positive": "Cluster phases and bubbly phase separation in active fluids: Reversal of\n  the Ostwald process: It is known that purely repulsive self-propelled colloids can undergo bulk\nliquid-vapor phase separation. In experiments and large scale simulations,\nhowever, more complex steady states are also seen, comprising a dynamic\npopulation of dense clusters in a sea of vapor, or dilute bubbles in a liquid.\nHere we show that these microphase-separated states should emerge generically\nin active matter, without any need to invoke system-specific details. We give a\ncoarse-grained description of them, and predict transitions between regimes of\nbulk phase separation and microphase separation. We achieve these results by\nextending the $\\phi^4$ field theory of passive phase separation to allow for\nall local currents that break detailed balance at leading order in the gradient\nexpansion. These local active currents, whose form we show to emerge from\ncoarse-graining of microscopic models, include a mixture of irrotational and\nrotational contributions, and can be viewed as arising from an effective\nnonlocal chemical potential. Such contributions influence, and in some\nparameter ranges reverse, the classical Ostwald process that would normally\ndrive bulk phase separation to completion."
    },
    {
        "anchor": "Shear thickening in molecular liquids characterized by inverse melting: We studied the rheological behavior of a molecular solution composed of\n$\\alpha$-cyclodextrin, water and 4-methylpyridine, a liquid known to undergo\ninverse melting, at different temperatures and concentrations. The system shows\na marked non-Newtonian behavior, exhibiting the typical signature of shear\nthickening. Specifically, a transition is observed from a Newtonian to a shear\nthickening regime at a critical shear rate $\\dot{\\gamma}_c$. The value of this\ncritical shear rate as a function of T follows an Arrhenius behavior\n$\\dot{\\gamma}_c(T)=$ B exp$(E_a/K_BT)$, with an activation energy $E_a$ close\nto the value of the hydrogen bond energy of the O-H group of the $\\alpha$-CD\nmolecules. We argue that the increase of viscosity vs shear rate (shear\nthickening transition) is due to the formation of hydrogen bonded aggregates\ninduced by the applied shear field. Finally, we speculate on the possible\ninterplay between the non-Newtonian rheology and the inverse melting behavior,\nproposing a single mechanism to be at the origin of both phenomena.",
        "positive": "Molecular Description of the Coil-to-Globule Transition of\n  Poly(N-isopropylacrylamide) in Water/Ethanol Mixture at Low Alcohol\n  Concentration: Poly(N-isopropylacrylamide), PNIPAM, is a widely studied polymer, which\nserves as a key constituent of nanostructured soft materials with responsive\nproperties. Upon increasing temperature the PNIPAM polymer chain undergoes a\nreversible coil-to-globule transition at ~305K, which is reflected by a volume\nphase transition in cross-linked architectures, such as microgels, valuable for\nmany practical applications. The addition of a cosolvent is a simple method to\ntune the transition temperature according to the specific purpose. In this\nstudy, we use atomistic molecular dynamics simulations to explore the solution\nbehavior of a PNIPAM chain in a mixture of water and ethanol, acting as\ncosolvent, at low alcohol concentration. Our simulations reproduce the\noccurrence of the coil-to-globule transition of the polymer chain at 289 K, a\ntemperature lower than that measured in water, in full agreement with\nexperimental findings. By monitoring the temperature evolution of structural\nand dynamical properties of the PNIPAM-water-ethanol ternary system, we detect\na localization of ethanol molecules at the polymer interface, mainly due to\ninteractions between isopropyl and ethyl groups. We observe that the transition\noccurs without a release of adsorbed ethanol molecules, but with a loss of\nwater molecules from the surrounding of PNIPAM hydrophobic moieties that\nfavours the aggregation of ethanol molecules close to the polymer. Our results\nsupport the idea that both the decreased chemical potential of water in the\nbulk of the mixture and the competition between water and ethanol molecules in\nthe interactions with the polymer play a driving role in the transition."
    },
    {
        "anchor": "Mode I fracture of a biopolymer gel: rate-dependent dissipation and\n  large deformations disentangled: We have designed a new experimental setup able to investigate fracture of\nsoft materials at small scales. At high crack velocity, where energy is mostly\ndissipated through viscoelastic processes, we observe an increasingly large\nhigh strain domain in the crack tip vicinity. Taking advantage of our ability\nto determine where linear elasticity breaks down, we derive a simple prediction\nfor the evolution of the energy release rate with the crack velocity.",
        "positive": "Rocking ratchet based on F1-ATPase in the absence of ATP: Bartussek, Hanggi and Kissner studied a rocking ratchet system, in which a\nBrownian particle is subject to an asymmetric periodic potential together with\nan oscillating force, and found that the direction of the macroscopic current\ncan be reversed by changing the parameter values characterizing the model\n[Europhys. Lett., 28 (1994) 459]. In this letter, we apply their ratchet theory\nto a rotary motor-protein, F1-ATPase. In this work, we construct a model of a\nrocking ratchet in which F1-ATPase rotates not as a result of ATP hydrolysis\nbut through the influence of an oscillating force. We then study the motion of\nF1-ATPase on the basis of molecular dynamics simulations of this coarse-grained\nprotein model. Although in the absence of ATP, F1-ATPase exhibits directionless\nBrownian motion when there exists no oscillating force, we observe directional\nmotion when we do apply an oscillating force. Furthermore, we observe that the\ndirection of rotation is reversed when we change the oscillation frequency."
    },
    {
        "anchor": "Polydomain structure and its origins in isotropic-genesis nematic\n  elastomers: We address the physics of nematic liquid crystalline elastomers randomly\ncrosslinked in the isotropic state. To do this, we construct a phenomenological\neffective replica Hamiltonian in terms of two order-parameter fields: one for\nthe vulcanization, the other for nematic alignment. Using a Gaussian\nvariational approach, we analyze both thermal and quenched fluctuations of the\nlocal nematic order, and find that, even for low temperatures, the\nmacroscopically isotropic polydomain state is stabilized by the network\nheterogeneity. For sufficiently strong disorder and low enough temperature, our\ntheory predicts unusual, short-range oscillatory structure in (i.e.,\nanti-alignment of) the local nematic order. The present approach, which\nnaturally takes into account the compliant, thermally fluctuating and\nheterogeneous features of elastomeric networks, can also be applied to other\ntypes of randomly crosslinked solids.",
        "positive": "Guided Neuronal Growth on Arrays of Biofunctionalized GaAs/InGaAs\n  Semiconductor Microtubes: We demonstrate embedded growth of cortical mouse neurons in dense arrays of\nsemiconductor microtubes. The microtubes, fabricated from a strained\nGaAs/InGaAs heterostructure, guide axon growth through them and enable\nelectrical and optical probing of propagating action potentials. The coaxial\nnature of the microtubes -- similar to myelin -- is expected to enhance the\nsignal transduction along the axon. We present a technique of suppressing\narsenic toxicity and prove the success of this technique by overgrowing\nneuronal mouse cells."
    },
    {
        "anchor": "Clogging of soft particles in 2D hoppers: Using experiments and simulations, we study the flow of soft particles\nthrough quasi-two-dimensional hoppers. The first experiment uses oil-in-water\nemulsion droplets in a thin sample chamber. Due to surfactants coating the\ndroplets, they easily slide past each other, approximating soft frictionless\ndisks. For these droplets, clogging at the hopper exit requires a narrow hopper\nopening only slightly larger than the droplet diameter. The second experiments\nuse soft hydrogel particles in a thin sample chamber, where we vary gravity by\nchanging the tilt angle of the chamber. For reduced gravity, clogging becomes\neasier, and can occur for larger hopper openings. Our simulations mimic the\nemulsion experiments and demonstrate that softness is a key factor controlling\nclogging: with stiffer particles or a weaker gravitational force, clogging is\neasier. The fractional amount a single particle is deformed under its own\nweight is a useful parameter measuring particle softness. Data from the\nsimulation and hydrogel experiments collapse when compared using this\nparameter. Our results suggest that prior studies using hard particles were in\na limit where the role of softness is negligible which causes clogging to occur\nwith significantly larger openings.",
        "positive": "Nonlinear Mechanical Response of DNA due to Anisotropic Bending\n  Elasticity: The response of a short DNA segment to bending is studied, taking into\naccount the anisotropy in the bending rigidities caused by the double-helical\nstructure. It is shown that the anisotropy introduces an effective nonlinear\ntwist-bend coupling that can lead to the formation of kinks and modulations in\nthe curvature and/or in the twist, depending on the values of the elastic\nconstants and the imposed deflection angle. The typical wavelength for the\nmodulations, or the distance between the neighboring kinks is found to be set\nby half of the DNA pitch."
    },
    {
        "anchor": "Simulation of magnetodielectric effect in magnetorheological elastomers: We present the results of numerical simulation of magnetodielectric effect\n(MDE) in magnetorheological elastomers (MRE) - the change of effective\npermittivity of elastomer placed under the external magnetic field. The\ncomputer model of effect is based on the assumption about the displacement of\nmagnetic particles inside the elastic matrix under the external magnetic field\nand the formation of chain-like structures. Such displacement of metallic\nparticles between the planes of capacitor leads to the change of capacity,\nwhich can be considered as a change of effective permittivity of elastomer\ncaused by magnetic field (magnetodielectric effect). In the literature mainly\n2D approach was used to model similar effect. In this paper we present the new\napproach of magnetorheological elastomers simulation - 3D-model of\nmagnetodielectric effect with ability to simulate systems of around 100000\nparticles. Within the framework of the model three types of particle size\ndistributions were simulated which gives an advantage over previously reported\napproaches. Lognormal size distribution was shown to give better qualitative\nmatch of the modeling and experimental results than monosized type. The\ndeveloped model resulted in perfect qualitative agreement with all experimental\ndata obtained earlier for Fe-based elastomers. The proposed model is useful to\nstudy these novel functional materials, analyze the features of\nmagnetodielectric effect and predict the optimal composition of\nmagnetorheological elastomers for further profound experimental study.",
        "positive": "Vesicle dynamics in large amplitude oscillatory extensional flow: Although the behavior of fluid-filled vesicles in steady flows has been\nextensively studied, far less is understood regarding the shape dynamics of\nvesicles in time-dependent oscillatory flows. Here, we investigate the\nnonlinear dynamics of vesicles in large amplitude oscillatory extensional\n(LAOE) flows using both experiments and boundary integral (BI) simulations. Our\nresults characterize the transient membrane deformations, dynamical regimes,\nand stress response of vesicles in LAOE in terms of reduced volume (vesicle\nasphericity), capillary number ($\\Ca$, dimensionless flow strength), and\nDeborah number ($\\De$, dimensionless flow frequency). Results from single\nvesicle experiments are found to be in good agreement with BI simulations\nacross a wide range of parameters. Our results reveal three distinct dynamical\nregimes based on vesicle deformation: pulsating, reorienting, and symmetrical\nregimes. We construct phase diagrams characterizing the transition of vesicle\nshapes between pulsating, reorienting, and symmetrical regimes within the\ntwo-dimensional Pipkin space defined by $\\De$ and $\\Ca$. Contrary to\nobservations on clean Newtonian droplets, vesicles do not reach a maximum\nlength twice per strain rate cycle in the reorienting and pulsating regimes.\nThe distinct dynamics observed in each regime result from a competition between\nthe flow frequency, flow time scale, and membrane deformation timescale. By\ncalculating the particle stresslet, we quantify the nonlinear relationship\nbetween average vesicle stress and strain rate. Additionally, we present\nresults on tubular vesicles that undergo shape transformation over several\nstrain cycles. Broadly, our work provides new information regarding the\ntransient dynamics of vesicles in time-dependent flows that directly informs\nbulk suspension rheology."
    },
    {
        "anchor": "DNA electrophoresis studied with the cage model: The cage model for polymer reptation, proposed by Evans and Edwards, and its\nrecent extension to model DNA electrophoresis, are studied by numerically exact\ncomputation of the drift velocities for polymers with a length L of up to 15\nmonomers. The computations show the Nernst-Einstein regime (v ~ E) followed by\na regime where the velocity decreases exponentially with the applied electric\nfield strength. In agreement with de Gennes' reptation arguments, we find that\nasymptotically for large polymers the diffusion coefficient D decreases\nquadratically with polymer length; for the cage model, the proportionality\ncoefficient is DL^2=0.175(2). Additionally we find that the leading correction\nterm for finite polymer lengths scales as N^{-1/2}, where N=L-1 is the number\nof bonds.",
        "positive": "Swim pressure on walls with curves and corners: The concept of swim pressure quantifies the average force exerted by\nmicroswimmers on confining walls in non-equilibrium. Here we explore how the\nswim pressure depends on the wall curvature and on the presence of sharp\ncorners in the wall. For active Brownian particles at high dilution, we present\na coherent framework which describes the force and torque on passive particles\nof arbitrary shape, in the limit of large particles compared to the persistence\nlength of the swimmer trajectories. The resulting forces can be used to derive,\nfor example, the activity-induced depletion interaction between two disks, as\nwell as to optimize the shape of a tracer particle for high swimming velocity.\nOur predictions are verifiable in experiments on passive obstacles exposed to a\nbath of bacteria or artificial microswimmers."
    },
    {
        "anchor": "Yielding, Rigidity, and Tensile Stress in Sheared Columns of Hexapod\n  Granules: Granular packings of non-convex or elongated particles can form free-standing\nstructures like walls or arches. For some particle shapes, such as staples, the\nrigidity arises from interlocking of pairs of particles, but the origins of\nrigidity for non-interlocking particles remains unclear. We report on\nexperiments and numerical simulations of sheared columns of \"hexapods,\"\nparticles consisting of three mutually orthogonal sphero-cylinders whose\ncenters coincide. We vary the length-to-diameter aspect ratio, $\\alpha$, of the\nsphero-cylinders and subject the packings to quasistatic direct shear. For\nsmall $\\alpha$, we observe a finite yield stress. For large $\\alpha$, however,\nthe column becomes rigid when sheared, supporting stresses that increase\nsharply with increasing strain. Analysis of X-ray micro-computed tomography\n(Micro-CT) data collected during the shear reveals that the stiffening is\nassociated with a tilted, oblate cluster of hexapods near the nominal shear\nplane in which particle deformation and average contact number both increase.\nSimulation results show that the particles are collectively under tension along\none direction even though they do not interlock pairwise. These tensions comes\nfrom contact forces carrying large torques, and they are perpendicular to the\ncompressive stresses in the packing. They counteract the tendency to dilate,\nthus stabilize the particle cluster.",
        "positive": "Controlling mechanical properties of a polymeric glass: In this work we use molecular simulations to examine methods of controlling\nmechanical properties of polymeric glass materials such as elastic moduli,\nmechanical heterogeneity as well as their glass transition temperature. We\nstudy filled and unfilled polymers and examine the effect of particle size,\nvolume fraction and polymer-particle interactions. We identify a relationship\nbetween mobility and dynamic heterogeneity with elastic moduli and glass\ntransition temperature."
    },
    {
        "anchor": "Smectic-A Free Standing Film of Lennard-Jones Spherocylinder Model: A spherocylinder-like molecule with a Lennard-Jones type interaction is\nproposed as a model of smectic-A (Sm-A) liquid crystals, which can form a\nfree-standing film. By means of Gibbs ensemble simulations, the isotropic,\nnematic, and Sm-A phases of the model fluid are found to coexist with a vapor\nphase; and the coexistence conditions of the liquid crystal phases with the\nvapor phase are determined. For a set of the interaction-parameters of the\nmodel molecule, the Sm-A free-standing film is produced below the bulk\nisotropic--Sm-A phase transition temperature by using Monte Carlo simulations.\nThe film tension of the Sm-A free-standing film is calculated and its\ndependencies on the temperature and on the number of molecules are discussed.",
        "positive": "How to quantify and avoid finite size effects in computational studies\n  of crystal nucleation: The case of homogeneous crystal nucleation: Finite size artifacts arise in molecular simulations of nucleation when\ncritical nuclei are too close to their periodic images. A rigorous\ndetermination of what constitutes too close is, however, a major challenge.\nRecently, we devised rigorous heuristics for detecting such artifacts based on\nour investigation of how system size impacts the rate of heterogeneous ice\nnucleation (Hussain, Haji-Akbari, \\emph{J. Chem. Phys.} \\textbf{154}, 014108,\n\\textbf{2021}). We identified the prevalence of critical nuclei spanning across\nthe periodic boundary, and the thermodynamic and structural properties of the\nliquid occupying the inter-image region as indicators of finite size artifacts.\nHere, we further probe the performance of such heuristics by examining the\ndependence of homogeneous crystal nucleation rates in the Lennard-Jones liquid\non system size. The rates depend non-monotonically on system size and vary by\nalmost six orders of magnitude for the range of system sizes considered here.\nWe confirm that the prevalence of spanning critical nuclei is the primary\nindicator of finite size artifacts and almost fully explains the observed\nvariations in rate. Proximity, or structuring of the inter-image liquid,\nhowever, is not as strong of an indicator due to the fragmented nature of\ncrystalline nuclei. As a result, the dependence of rate on system size is\nsubtle for the systems with a minuscule fraction of spanning critical nuclei.\nThese observations indicate that our heuristics are universally applicable to\ndifferent modes of nucleation (homogeneous and heterogeneous) in different\nsystems even if they might be overly stringent for homogeneous\nnucleation,~e.g.,~in the LJ system."
    },
    {
        "anchor": "Hydrodynamic Interactions in Ion Transport -- Theory and Simulation: We present a hydrodynamic theory describing pair diffusion in systems with\nperiodic boundary conditions, thereby generalizing earlier work on\nself-diffusion [D\\\"unweg and Kremer, J. Chem. Phys. 1993, 99, 6983-6997; Yeh\nand Hummer, J. Phys. Chem. B 2004, 108, 15873-15879]. Its predictions are\ncompared to Molecular Dynamics simulations for a liquid carbonate electrolyte\nand two ionic liquids, for which we characterize the correlated motion between\ndistinct ions. Overall, we observe good agreement between theory and simulation\ndata, highlighting that hydrodynamic interactions universally dictate ion\ncorrelations. However, when summing over all ion pairs in the system to obtain\nthe cross-contributions to the total cationic or anionic conductivity, the\nhydrodynamic interactions between ions with like and unlike charges largely\ncancel. Consequently, significant conductivity contributions only arise from\ndeviations from a hydrodynamic flow field of an ideal fluid, that is, from the\nlocal electrolyte structure as well as from relaxation processes in the\nsubdiffusive regime. In case of ionic liquids, the momentum-conservation\nconstraint additionally is vital, which we study by employing different ionic\nmasses in the simulations. Our formalism will likely also be helpful to\nestimate finite-size effects of the conductivity or of Maxwell-Stefan\ndiffusivities in simulations.",
        "positive": "Protein Unfolding and Aggregation near a Hydrophobic Interface: The behavior of proteins near interfaces is relevant for biological and\nmedical purposes. Previous results in bulk show that, when the protein\nconcentration increases, the proteins unfold and, at higher concentrations,\naggregate. Here, we study how the presence of a hydrophobic surface affects\nthis course of events. To this goal, we use a coarse-grained model of proteins\nand study by simulations their folding and aggregation near an ideal\nhydrophobic surface in an aqueous environment by changing parameters such as\ntemperature and hydrophobic strength, related, e.g., to ions concentration. We\nshow that the hydrophobic surface, as well as the other parameters, affect both\nthe protein unfolding and aggregation. We discuss the interpretation of these\nresults and define future lines for further analysis, with their possible\nimplications in neurodegenerative diseases."
    },
    {
        "anchor": "Two Transitions in the Damping of a Unitary Fermi Gas: We measure the temperature dependence of the radial breathing mode in an\noptically trapped, strongly-interacting Fermi gas of $^6$Li, just above the\ncenter of a broad Feshbach resonance. The frequency remains close to the\nunitary hydrodynamic value, while the damping rate reveals transitions at two\nwell-separated temperatures, consistent with the existence of atom pairs above\na superfluid transition.",
        "positive": "Stretchable liquid crystal blue phase gels: Liquid crystalline polymers are materials of considerable scientific interest\nand technological value to society [1-3]. An important subset of such materials\nexhibit rubber-like elasticity; these can combine the remarkable optical\nproperties of liquid crystals with the favourable mechanical properties of\nrubber and, further, exhibit behaviour not seen in either type of material\nindependently [2]. Many of their properties depend crucially on the particular\nmesophase employed. Stretchable liquid crystalline polymers have previously\nbeen demonstrated in the nematic, chiral nematic, and smectic mesophases [2,4].\nHere were report the fabrication of a stretchable gel of blue phase I, which\nforms a self-assembled, three-dimensional photonic crystal that may have its\noptical properties manipulated by an applied strain and, further, remains\nelectro-optically switchable under a moderate applied voltage. We find that,\nunlike its undistorted counterpart, a mechanically deformed blue phase exhibits\na Pockels electro-optic effect, which sets out new theoretical challenges and\nnew possibilities for low-voltage electro-optic devices."
    },
    {
        "anchor": "Interparticle hydrogen bonding can elicit shear jamming in dense\n  suspensions: Dense suspensions of hard particles in a liquid can exhibit strikingly\ncounter-intuitive behavior, such as discontinuous shear thickening (DST) [1-8]\nand reversible shear jamming (SJ) into a state with finite yield stress [9-13].\nRecent studies identified a stress-activated crossover from hydrodynamic\ninteractions to frictional particle contacts to be key for these behaviors\n[2-4, 6-8, 10, 14]. However, many suspensions exhibit only DST and not SJ. Here\nwe show that particle surface chemistry can play a central role in creating\nconditions that allow for SJ. We find the system's ability to form\ninterparticle hydrogen bonds when sheared into contact elicits SJ. We\ndemonstrate this with charge-stabilized polymer microspheres and non-spherical\ncornstarch particles, controlling hydrogen bond formation with solvents. The\npropensity for SJ is quantified by tensile tests [13] and linked to an enhanced\nfriction by atomic force microscopy. Our results extend the fundamental\nunderstanding of the SJ mechanism and open new avenues for designing strongly\nnon-Newtonian fluids.",
        "positive": "Field induced anisotropic cooperativity in a magnetic colloidal glass: The translational dynamics in a repulsive colloidal glass-former is probed by\ntime-resolved X-ray Photon Correlation Spectroscopy. In this dense dispersion\nof charge-stabilized and magnetic nanoparticles, the interaction potential can\nbe tuned, from quasi-isotropic to anisotropic by applying an external magnetic\nfield. Structural and dynamical anisotropies are reported on interparticle\nlengthscales associated with highly anisotropic cooperativity, almost two\norders of magnitude larger in the field direction than in the perpendicular\ndirection and in zero field."
    },
    {
        "anchor": "Spin injection into a short DNA chain: Quantun spin transport through a short DNA chain connected to ferromagnetic\nelectrodes has been investigated by the transfer matrix method. We describe the\nsystem by a tight-binding model where the parameters are extracted from the\nexperimental data and realistic metal energy bands. For ferromagnetic iron\nelectrodes, the magnetoresistance of a 30-basepair Poly(G)-Poly(C) DNA is found\nto be lower than 10% at a bias of < 4 V, but can rach up to 20% at a bias of 5\nV. In the presence of the spin-flip mechanism, the magnetoresistance is\nsignificantly enhanced when the spin-flip coupling is weak but as the coupling\nbecomes stronger the decreasing magnetoresistance develops an oscillatory\nbehavior.",
        "positive": "Cell Division and Motility Enable Hexatic Order in Biological Tissues: Biological tissues transform between solid-like and liquid-like states in\nmany fundamental physiological events. Recent experimental observations further\nsuggest that in two-dimensional epithelial tissues these solid-liquid\ntransformations can happen via intermediate states akin to the intermediate\nhexatic phases observed in equilibrium two-dimensional melting. The hexatic\nphase is characterized by quasi-long-range (power-law) orientational order but\nno translational order, thus endowing some structure to an otherwise\nstructureless fluid. While it has been shown that hexatic order in tissue\nmodels can be induced by motility and thermal fluctuations, the role of cell\ndivision and apoptosis (birth and death) has remained poorly understood,\ndespite its fundamental biological role. Here we study the effect of cell\ndivision and apoptosis on global hexatic order within the framework of the\nself-propelled Voronoi model of tissue. Although cell division naively destroys\norder and active motility facilitates deformations, we show that their combined\naction drives a liquid-hexatic-liquid transformation as the motility increases.\nThe hexatic phase is accessed by the delicate balance of dislocation defect\ngeneration from cell division and the active binding of\ndisclination-antidisclination pairs from motility. We formulate a mean-field\nmodel to elucidate this competition between cell division and motility and the\nconsequent development of hexatic order."
    },
    {
        "anchor": "Self-assembly of colloidal particles in deformation landscapes of\n  electrically driven layer undulations in cholesteric liquid crystals: We study elastic interactions between colloidal particles and deformation\nlandscapes of undulations in a cholesteric liquid crystal under an electric\nfield applied normal to cholesteric layers. The onset of undulation instability\nis influenced by the presence of colloidal inclusions and, in turn, layers'\nundulations mediate the spatial patterning of particle locations. We find that\nthe bending of cholesteric layers around a colloidal particle surface prompts\nthe local nucleation of an undulations lattice at electric fields below the\nwell-defined threshold known for liquid crystals without inclusions, and that\nthe onset of the resulting lattice is locally influenced, both dimensionally\nand orientationally, by the initial arrangements of colloids defined using\nlaser tweezers. Spherical particles tend to spatially localize in the regions\nof strong distortions of the cholesteric layers, while colloidal nanowires\nexhibit an additional preference for multistable alignment offset along various\nvectors of the undulations lattice. Magnetic rotation of superparamagnetic\ncolloidal particles couples with the locally distorted helical axis and\nundulating cholesteric layers in a manner that allows for a controlled\nthree-dimensional translation of these particles. These interaction modes lend\ninsight into the physics of liquid crystal structure-colloid elastic\ninteractions, as well as point the way towards guided self-assembly of\nreconfigurable colloidal composites with potential applications in diffraction\noptics and photonics.",
        "positive": "Yielding and Strain Stiffening in Entangled Assemblies of Frictional\n  Granular Chains: Packings of macroscopic granular chains capture some of the essential aspects\nof molecular polymer systems and have been suggested as a paradigm to\nunderstand the physics on a molecular scale. However, here we demonstrate that\nthe interparticle friction $\\mu$ in granular chain packings, which has no\ncounterpart in polymer systems, leads to a nontrivial yielding and rheological\nresponse. Based on discrete element simulations we study the nonlinear rheology\nof random packings of granular chains under large amplitude oscillatory shear.\nWe find that the maximum stress and the penetration depth of the shear\ndeformation into the material bulk are nonmonotonic functions of friction with\nextrema at intermediate values of $\\mu$. We also show that the regularly\nrepeated gaps between the adjacent grains, which are special to commercial\ngranular chains, broaden the shear zone and enhance the entanglements in the\nsystem by promoting the interlocking events between chains. These topological\nconstraints can significantly increase the degree of strain stiffening. Our\nfindings highlight the differences between the physics of granular chain\npackings and molecular polymer systems."
    },
    {
        "anchor": "Free energy landscape of two-state protein Acylphosphatase with large\n  contact order revealed by force-dependent folding and unfolding dynamics: Acylphosphatase (AcP) is a small protein with 98 amino acid residues that\ncatalyzes the hydrolysis of carboxyl-phosphate bonds. AcP is a typical\ntwo-state protein with slow folding rate due to its relatively large contact\norder in the native structure. The mechanical properties and unfolding behavior\nof AcP has been studied by atomic force microscope. But the folding and\nunfolding dynamics at low forces has not been reported. Here using stable\nmagnetic tweezers, we measured the force-dependent folding rates within a force\nrange from 1 pN to 3 pN, and unfolding rates from 15 pN to 40 pN. The obtained\nunfolding rates show different force sensitivities at forces below and above\n~27 pN, which determines a free energy landscape with two energy barriers. Our\nresults indicate that the free energy landscape of small globule proteins have\ngeneral Bactrian camel shape, and large contact order of the native state\nproduces a high barrier dominate at low forces.",
        "positive": "Fluctuation Spectra and Force Generation in Non-equilibrium Systems: Many biological systems are appropriately viewed as passive inclusions\nimmersed in an active bath: from proteins on active membranes to microscopic\nswimmers confined by boundaries. The non-equilibrium forces exerted by the\nactive bath on the inclusions or boundaries often regulate function, and such\nforces may also be exploited in artificial active materials. Nonetheless, the\ngeneral phenomenology of these active forces remains elusive. We show that the\nfluctuation spectrum of the active medium, the partitioning of energy as a\nfunction of wavenumber, controls the phenomenology of force generation. We find\nthat for a narrow, unimodal spectrum, the force exerted by a non-equilibrium\nsystem on two embedded walls depends on the width and the position of the peak\nin the fluctuation spectrum, and oscillates between repulsion and attraction as\na function of wall separation. We examine two apparently disparate examples:\nthe Maritime Casimir effect and recent simulations of active Brownian\nparticles. A key implication of our work is that important non-equilibrium\ninteractions are encoded within the fluctuation spectrum. In this sense the\nnoise becomes the signal."
    },
    {
        "anchor": "A delayed yielding transition in mechanically annealed binary glasses at\n  finite temperature: The influence of strain amplitude, glass stability and thermal fluctuations\non shear band formation and yielding transition is studied using molecular\ndynamics simulations. The model binary mixture is first gradually cooled below\nthe glass transition temperature and then periodically deformed to access a\nbroad range of potential energy states. We find that the critical strain\namplitude becomes larger for highly annealed glasses within about one thousand\nshear cycles. Moreover, upon continued loading at a fixed strain amplitude, the\nyielding transition is delayed in glasses mechanically annealed to lower energy\nstates. It is also demonstrated that nucleation of a small cluster of atoms\nwith large nonaffine displacements precedes a sharp energy change associated\nwith the yielding transition. These results are important for thermal and\nmechanical processing of amorphous alloys with tunable mechanical and physical\nproperties.",
        "positive": "Rheological Model for Wood: Wood as the most important natural and renewable building material plays an\nimportant role in the construction sector. Nevertheless, its hygroscopic\ncharacter basically affects all related mechanical properties leading to\ndegradation of material stiffness and strength over the service life.\nAccordingly, to attain reliable design of the timber structures, the influence\nof moisture evolution and the role of time- and moisture-dependent behaviors\nhave to be taken into account. For this purpose, in the current study a 3D\northotropic elasto-plastic, visco-elastic, mechano-sorptive constitutive model\nfor wood, with all material constants being defined as a function of moisture\ncontent, is presented. The corresponding numerical integration approach, with\nadditive decomposition of the total strain is developed and implemented within\nthe framework of the finite element method (FEM). Moreover to preserve a\nquadratic rate of asymptotic convergence the consistent tangent operator for\nthe whole model is derived.\n  Functionality and capability of the presented material model are evaluated by\nperforming several numerical verification simulations of wood components under\ndifferent combinations of mechanical loading and moisture variation.\nAdditionally, the flexibility and universality of the introduced model to\npredict the mechanical behavior of different species are demonstrated by the\nanalysis of a hybrid wood element. Furthermore, the proposed numerical approach\nis validated by comparisons of computational evaluations with experimental\nresults."
    },
    {
        "anchor": "Variational Approach to the Modulational Instability: We study the modulational stability of the nonlinear Schr\\\"odinger equation\n(NLS) using a time-dependent variational approach. Within this framework, we\nderive ordinary differential equations (ODEs) for the time evolution of the\namplitude and phase of modulational perturbations. Analyzing the ensuing ODEs,\nwe re-derive the classical modulational instability criterion. The case\n(relevant to applications in optics and Bose-Einstein condensation) where the\ncoefficients of the equation are time-dependent, is also examined.",
        "positive": "Simulation of cohesive fine powders under a plane shear: Three dimensional molecular dynamics simulations of cohesive dissipative\npowders under a plane shear are performed. We find the various phases depending\non the dimensionless shear rate and the dissipation rate as well as the\ndensity. We also find that the shape of clusters depends on the initial\ncondition of velocities of particles when the dissipation is large. Our simple\nstochastic model reproduces the non-Gaussian velocity distribution function\nappearing in the coexistence phase of a gas and a plate."
    },
    {
        "anchor": "Soft particles at a fluid interface: Particles added to a fluid interface can be used as a surface stabilizer in\nthe food, oil and cosmetic industries. As an alternative to rigid particles, it\nis promising to consider highly deformable particles that can adapt their\nconformation at the interface. In this study we compute the shapes of soft\nelastic particles using molecular dynamics simulations of a cross-linked\npolymer gel, complemented by continuum calculations based on linear elasticity.\nIt is shown that the particle shape is not only affected by the Young's modulus\nof the particle, but also strongly depends on whether the gel is partially or\ncompletely wetting the fluid interface. We find that the molecular simulations\nfor the partially wetting case are very accurately described by the continuum\ntheory. By contrast, when the gel is completely wetting the fluid interface the\nlinear theory breaks down and we reveal that molecular details have a strong\ninfluence on the equilibrium shape.",
        "positive": "Breakdown of inverse morphologies in charged diblock copolymers: Brownian Dynamics simulations are carried out to understand the effect of\ntemperature and dielectric constant of the medium on microphase separation of\ncharged-neutral diblock copolymer systems. For different dielectric media, we\nfocus on the effect of temperature on the morphology and dynamics of model\ncharged diblock copolymers. In this study we examine in detail a system of\npartially charged block copolymer consisting of 75% neutral blocks and 25% of\ncharged blocks with 50% degree of ionization. Our investigations show that due\nto the presence of strong electrostatic interactions between the charged block\nand counterions, the block copolymer morphologies are rather different than\ntheir neutral counterpart at low dielectric constant, however at high\ndielectric constant the neutral diblock behaviors are observed. This article\nhighlights the effect of dielectric constant of two different media on\ndifferent thermodynamic and dynamic quantities. At low dielectric, the\nmorphologies are a direct outcome of the ion-counterion multiplet formation. At\nhigh dielectric, these charged diblocks behavior resembles that of neutral and\nweakly charged polymers with sustainable long-range order. Similar behavior has\nbeen observed in chain swelling, albeit with small changes in swelling ratio\nfor large change in polarity of the medium. The results of our simulations\nagree with recent experimental results and are consistent with recent\ntheoretical predictions of counterion adsorption on flexible polyelectrolytes."
    },
    {
        "anchor": "Lifting map for ordered surfaces: When a material surface is functionalized so as to acquire some type of\norder, functionalization of which soft condensed matter systems have recently\nprovided many interesting examples, the modeller faces an alternative. Either\nthe order is described on the curved, physical surface where it belongs, or it\nis described on a flat surface that is unrolled as pre-image of the physical\nsurface under a suitable height function. This paper proposes a general method\nthat pursues the latter avenue by lifting whatever order tensor is deemed\nappropriate from a flat to a curved surface. To produce a specific application,\nwe specialize this method to nematic shells, for which it also provides a\nsimple, but convincing interpretation of the outcomes of some\nmolecular-dynamics experiments on ellipsoidal shells.",
        "positive": "Monte Carlo simulations of the HP model (the \"Ising model\" of protein\n  folding): Using Wang-Landau sampling with suitable Monte Carlo trial moves (pull moves\nand bond-rebridging moves combined) we have determined the density of states\nand thermodynamic properties for a short sequence of the HP protein model. For\nfree chains these proteins are known to first undergo a collapse \"transition\"\nto a globule state followed by a second \"transition\" into a native state. When\nplaced in the proximity of an attractive surface, there is a competition\nbetween surface adsorption and folding that leads to an intriguing sequence of\n\"transitions\". These transitions depend upon the relative interaction strengths\nand are largely inaccessible to \"standard\" Monte Carlo methods."
    },
    {
        "anchor": "Mean-field model of jet formation in a collapsing Bose-Einstein\n  condensate: We perform a systematic numerical study, based on the time-dependent\nGross-Pitaevskii equation, of jet formation in collapsing and exploding\nBose-Einstein condensates as in the experiment by Donley et al [2001 Nature 412\n295]. In the actual experiment, via a Feshbach resonance, the scattering length\nof atomic interaction was suddenly changed from positive to negative on a\npre-formed condensate. Consequently, the condensate collapsed and ejected atoms\nvia explosion. On a disruption of collapse by suddenly changing the scattering\nlength to zero a radial jet of atoms was formed in the experiment. We present a\nsatisfactory account of jet formation under the experimental conditions as well\nas make predictions beyond experimental conditions which can be verified in\nfuture experiments.",
        "positive": "Equilibration of High Molecular-Weight Polymer Melts: A Hierarchical\n  Strategy: A strategy is developed for generating equilibrated high molecular-weight\npolymer melts described with microscopic detail by sequentially backmapping\ncoarse-grained (CG) configurations. The microscopic test model is generic but\nretains features like hard excluded volume interactions and realistic melt\ndensities. The microscopic representation is mapped onto a model of soft\nspheres with fluctuating size, where each sphere represents a microscopic\nsubchain with $N_{\\rm b}$ monomers. By varying $N_{\\rm b}$ a hierarchy of CG\nrepresentations at different resolutions is obtained. Within this hierarchy, CG\nconfigurations equilibrated with Monte Carlo at low resolution are sequentially\nfine-grained into CG melts described with higher resolution. A Molecular\nDynamics scheme is employed to slowly introduce the microscopic details into\nthe latter. All backmapping steps involve only local polymer relaxation thus\nthe computational efficiency of the scheme is independent of molecular weight,\nbeing just proportional to system size. To demonstrate the robustness of the\napproach, microscopic configurations containing up to $n=1000$ chains with\npolymerization degrees $N=2000$ are generated and equilibration is confirmed by\nmonitoring key structural and conformational properties. The extension to much\nlonger chains or branched polymers is straightforward."
    },
    {
        "anchor": "Surface tensiometry of phase separated protein and polymer droplets by\n  the sessile drop method: Phase separated macromolecules play essential roles in many biological and\nsynthetic systems. Physical characterization of these systems can be\nchallenging because of limited sample volumes, particularly for phase-separated\nproteins. Here, we demonstrate that a classic method for measuring the surface\ntension of liquid droplets, based on the analysis of the shape of a sessile\ndroplet, can be effectively scaled down for this application. The connection\nbetween droplet shape and surface tension relies on the density difference\nbetween the droplet and its surroundings. This can be determined with small\nsample volumes in the same setup by measuring the droplet sedimentation\nvelocity. An interactive MATLAB script for extracting the capillary length from\na droplet image is included in the ESI.",
        "positive": "Softer than soft: diving into squishy granular matter: Softer than soft, squishy granular matter is composed of grains capable of\nsignificantly changing their shape (typically larger than 10% of deformation)\nwithout tearing or breaking. Because of the difficulty to test these materials\nexperimentally and numerically, such a family of discrete systems remains\nlargely ignored in the granular matter physics field despite being commonly\nfound in nature and industry. Either from a numerical, experimental, or\nanalytical point of view, the study of highly deformable granular matter\ninvolves several challenges covering, for instance: ($i$) the need to include a\nlarge diversity of grain rheology, ($ii$) the need to consider \\dc{large\nmaterial} deformations, and ($iii$) the analysis upon the effects the large\nbody distortion has on the global scale. In this article, we propose a thorough\ndefinition of these squishy granular systems, and we summarize the upcoming\nchallenges in their study."
    },
    {
        "anchor": "End-monomer dynamics in semiflexible polymers: Spurred by an experimental controversy in the literature, we investigate the\nend-monomer dynamics of semiflexible polymers through Brownian hydrodynamic\nsimulations and dynamic mean-field theory. Precise experimental observations\nover the last few years of end-monomer dynamics in the diffusion of\ndouble-stranded DNA have given conflicting results: one study indicated an\nunexpected Rouse-like scaling of the mean squared displacement (MSD) r^2(t) ~\nt^(1/2) at intermediate times, corresponding to fluctuations at length scales\nlarger than the persistence length but smaller than the coil size; another\nstudy claimed the more conventional Zimm scaling r^2(t) ~ t^(2/3) in the same\ntime range. We find a novel intermediate dynamical regime where the effective\nlocal exponent of the end-monomer MSD, alpha(t) = d log r^2(t)/ d log t, drops\nbelow the Zimm value of 2/3 for sufficiently long chains. The deviation from\nthe Zimm prediction increases with chain length, though it does not reach the\nRouse limit of 1/2. The qualitative features of this intermediate regime, in\nparticular the variation of alpha(t) with chain and persistence lengths, can be\nreproduced through a heuristic scaling argument. Anomalously low values of the\neffective exponent alpha are explained by hydrodynamic effects related to the\nslow crossover from dynamics on length scales smaller than the persistence\nlength to dynamics on larger length scales.",
        "positive": "Transitions between Inherent Structures in Water: The energy landscape approach has been useful to help understand the dynamic\nproperties of supercooled liquids and the connection between these properties\nand thermodynamics. The analysis in numerical models of the inherent structure\n(IS) trajectories -- the set of local minima visited by the liquid -- offers\nthe possibility of filtering out the vibrational component of the motion of the\nsystem on the potential energy surface and thereby resolving the slow\nstructural component more efficiently. Here we report an analysis of an IS\ntrajectory for a widely-studied water model, focusing on the changes in\nhydrogen bond connectivity that give rise to many IS separated by relatively\nsmall energy barriers. We find that while the system \\emph{travels} through\nthese IS, the structure of the bond network continuously modifies, exchanging\nlinear bonds for bifurcated bonds and usually reversing the exchange to return\nto nearly the same initial configuration. For the 216 molecule system we\ninvestigate, the time scale of these transitions is as small as the simulation\ntime scale ($\\approx 1$ fs). Hence for water, the transitions between each of\nthese IS is relatively small and eventual relaxation of the system occurs only\nby many of these transitions. We find that during IS changes, the molecules\nwith the greatest displacements move in small ``clusters'' of 1-10 molecules\nwith displacements of $\\approx 0.02-0.2$ nm, not unlike simpler liquids.\nHowever, for water these clusters appear to be somewhat more branched than the\nlinear ``string-like'' clusters formed in a supercooled Lennar d-Jones system\nfound by Glotzer and her collaborators."
    },
    {
        "anchor": "Intrinsic structural features in jammed disordered packing of\n  monodisperse spheres: A new tetrahedral structure model was developed and the geometrical structure\nof jammed disordered packings of monodisperse spheres with different friction\ncoefficients was systematically characterized. An intrinsic structure feature\nis revealed for all jammed disordered packings, which is determined only by the\npacking fraction, independent of interparticle friction. Moreover, the\nstructural configurations associated with crystal phases are more prevalent\nthan the geometric frustrated ones. In addition, irregular simplexes are found\nto play a key role in an increase in density, rather than regular simplexes, in\ncontrast to previous expectation. Our model provides an intrinsic structural\nbasis for the random close packing.",
        "positive": "Size dependence of dynamic fluctuations in liquid and supercooled water: We study the evolution of dynamic fluctuations averaged over different space\nlengths and time scales to characterize spatially and temporally heterogeneous\nbehavior of TIP4P/2005 water in liquid and supercooled states. Analysing a\nmillion particle simulated system we provide evidence of the existence, upon\nsupercooling, of a significant enhancement of spatially localized dynamic\nfluctuations stemming from regions of correlated mobile molecules. We show that\nboth the magnitude of the departure from the value expected for the system-size\ndependence of an uncorrelated system and the molecular size at which such\ntrivial regime is finally recovered clearly increase upon supercooling. This\nprovides a means to estimate an upper limit to the maximum length scale of\ninfluence of the regions of correlated mobile molecules. Notably, such upper\nlimit grows two orders of magnitude on cooling, reaching a value corresponding\nto a few thousand molecules at the lowest investigated temperature."
    },
    {
        "anchor": "Pressure-driven wrinkling of soft inner-lined tubes: Wrinkling of an inextensible elastic lining of an inner-lined tube under\nimposed pressure is considered. A simple equation modeling the elastic\nproperties of the lining, the pressure, and the soft-substrate forces is\nderived. This equation aims to capture the wrinkling response of arterial\nendothelium to blood pressure changes. Numerical continuation is used to\nconstruct a bifurcation diagram as a function of the imposed pressure for\nin-plane deformations, in excellent agreement with weakly nonlinear theory,\nwhich we also develop. Our approach explains how the wavelength and amplitude\nof the wrinkles are selected as a function of the parameters in compressed\nwrinkling systems and shows how localized folds and mixed-mode states form in\nsecondary bifurcations from wrinkled states.",
        "positive": "Generic Conditions for Hydrodynamic Synchronization: Synchronization of actively oscillating organelles such as cilia and flagella\nfacilitates self-propulsion of cells and pumping fluid in low Reynolds number\nenvironments. To understand the key mechanism behind synchronization induced by\nhydrodynamic interaction, we study a model of rigid-body rotors making fixed\ntrajectories of arbitrary shape under driving forces that are arbitrary\nfunctions of the phases. For a wide class of geometries, we obtain the\nnecessary and sufficient conditions for synchronization of a pair of rotors. We\nalso find a novel synchronized pattern with a time-dependent phase shift. Our\nresults shed light on the role of hydrodynamic interactions in biological\nsystems, and could help in developing efficient mixing and transport strategies\nin microfluidic devices."
    },
    {
        "anchor": "Modeling elastic instabilities in nematic elastomers: Liquid crystal elastomers are cross-linked polymer networks covalently bonded\nwith liquid crystal mesogens. In the nematic phase, due to strong coupling\nbetween mechanical strain and orientational order, these materials display\nstrain-induced instabilities associated with formation and evolution of\norientational domains. Using a 3-d finite element elastodynamics simulation, we\ninvestigate one such instability, the onset of stripe formation in a monodomain\nfilm stretched along an axis perpendicular to the nematic director. In our\nsimulation we observe the formation of striped domains with alternating\ndirector rotation. This model allows us to explore the fundamental physics\ngoverning dynamic mechanical response of nematic elastomers and also provides a\npotentially useful computational tool for engineering device applications.",
        "positive": "Rate-dependent slip boundary conditions for simple fluids: The dynamic behavior of the slip length in a fluid flow confined between\natomically smooth surfaces is investigated using molecular dynamics\nsimulations. At weak wall-fluid interactions, the slip length increases\nnonlinearly with the shear rate provided that the liquid/solid interface forms\nincommensurable structures. A gradual transition to the linear rate-dependence\nis observed upon increasing the wall-fluid interaction. We found that the slip\nlength can be well described by a function of a single variable that in turn\ndepends on the in-plane structure factor, contact density and temperature of\nthe first fluid layer near the solid wall. Extensive simulations show that this\nformula is valid in a wide range of shear rates and wall-fluid interactions."
    },
    {
        "anchor": "Measures of mixing quality in open flows with chaotic advection: We address the evaluation of mixing efficiency in experiments of chaotic\nmixing inside an open-flow channel. Since the open flow continuously brings new\nfluid into the limited mixing region, it is difficult to define relevant mixing\nindices, as fluid particles experience typically very different stretching and\nmixing histories. The repeated stretching and folding of a spot of dye leads to\na persistent pattern. We propose that the normalized standard deviation of this\ncharacteristic pattern is a good measure of the mixing quality of the flow. We\ndiscuss the link between this measure and mixing of continuously-injected dye,\nand investigate it using an idealized map.",
        "positive": "Electrically Deformable Liquid Marbles: Liquid marbles, which are droplets coated with a hydrophobic powder, were\nexposed to a uniform electric field. It was established that a threshold value\nof the electric field, 15 cgse, should be surmounted for deformation of liquid\nmarbles. The shape of the marbles was described as a prolate spheroid. The\nsemi-quantitative theory describing deformation of liquid marbles in a uniform\nelectric field is presented. The scaling law relating the radius of the contact\narea of the marble to the applied electric field shows a satisfactory agreement\nwith the experimental data."
    },
    {
        "anchor": "Internal dissipation of a polymer: The dynamics of flexible polymer molecules are often assumed to be governed\nby hydrodynamics of the solvent. However there is considerable evidence that\ninternal dissipation of a polymer contributes as well. Here we investigate the\ndynamics of a single chain in the absence of solvent to characterize the nature\nof this internal friction. We model the chains as freely hinged but with\nlocalized bond angles and 3-fold symmetric dihedral angles. We show that the\ndamping is close but not identical to Kelvin damping, which depends on the\nfirst temporal and second spatial derivative of monomer position. With no\ninternal potential between monomers, the magnitude of the damping is small for\nlong wavelengths and weakly damped oscillatory time dependent behavior is seen\nfor a large range of spatial modes. When the size of the internal potential is\nincreased, such oscillations persist, but the damping becomes larger. However\nunderdamped motion is present even with quite strong dihedral barriers for long\nenough wavelengths.",
        "positive": "Symmetries and invariant solutions of the wave equation for shear\n  disturbances in soft solids: The Lie-group approach was applied to determine symmetries of the third-order\nnon-linear equation formulated for description of shear elastic disturbances in\nsoft solids. Invariant solutions to this equation are derived and it turned out\nthat they could represent outgoing or incoming exponentially decaying or\nunbounded disturbances."
    },
    {
        "anchor": "The alignment of nematic liquid crystal by the Ti layer processed by\n  nonlinear laser lithography: It is well known that the alignment of liquid crystals can be realized by\nrubbing or photoalignment technologies. Recently nonlinear laser lithography\nwas introduced as a fast, relatively low-cost method for large area\nnano-grating fabrication based on laser-induced periodic surface structuring.\nIn this letter for the first time the usage of the nonlinear laser lithography\nas a perspective method of the alignment of nematics was presented. By\nnonlinear laser lithography, microgrooves with about 1 {\\mu}m period were\nformed on Ti layer. The microstructured Ti layer was coated with\noxidianiline-polyimide film with annealing of the polymer followed without any\nfurther processing. Aligning properties of microstructured Ti layers were\nexamined with combined twist LC cell. The dependencies of the twist angle of LC\ncells and azimuthal anchoring energy of layers on scanning speed and power of\nlaser beam during processing of the Ti layer were the focus of our studies as\nwell. The maximum azimuthal anchoring energy, obtained for pure microstructured\nTi layer, is comparable with photoalignment technology. It was found that the\ndeposition of polyimide film on microstructured Ti layer leads to the gain\neffect of the azimuthal anchoring energy. Also, AFM study of aligning surfaces\nwas carried out.",
        "positive": "Wetting behavior of a colloidal particle trapped at a composite\n  liquid-vapor interface of a binary liquid mixture: A partially miscible binary liquid mixture, composed of A and B particles, is\nconsidered theoretically under conditions for which a stable A-rich liquid\nphase is in thermal equilibrium with the vapor phase. The B-rich liquid is\nmetastable. The liquids and the thermodynamic conditions are chosen such, that\nthe interface between the A-rich liquid and the vapor contains an intervening\nwetting film of the B-rich phase. In order to obtain information about the\nlarge-scale fluid structure around a colloidal particle, which is trapped at\nsuch a composite liquid-vapor interface, three related and linked wetting\nphenomena at planar liquid-vapor, wall-liquid, and wall-vapor interfaces are\nstudied analytically, using classical density functional theory in conjunction\nwith the sharp-kink approximation for the number density profiles of the A and\nB particles. If in accordance with the so-called mixing rule the strength of\nthe A-B interaction is given by the geometric mean of the strengths of the A-A\nand B-B interactions, and similarly the ratio between the wall-A and the wall-B\ninteraction, the scenario, in which the colloid is enclosed by a film of the\nB-rich liquid, can be excluded. Up to six distinct wetting scenarios are\npossible, if the above mixing rules for the fluid-wall and for the fluid-fluid\ninteractions are relaxed. The way the space of system parameters is divided\ninto domains corresponding to the six scenarios, and which of the domains\nactually appear, depends on the signs of the deviations from the mixing rule\nprescriptions. Relevant domains emerge, if the ratio between the strengths of\nthe wall-A and the wall-B interactions is reduced as compared to the mixing\nrule prescription, or if the strength of the A-B interaction is increased to\nvalues above the one from the mixing rule prescription. The range, within which\nthe contact angle may vary inside the various domains, is also studied."
    },
    {
        "anchor": "Electrical conductivity of dispersions: from dry foams to dilute\n  suspensions: We present new data for the electrical conductivity of foams in which the\nliquid fraction ranges from two to eighty percent. We compare with a\ncomprehensive collection of prior data, and we model all results with simple\nempirical formul\\ae. We achieve a unified description that applies equally to\ndry foams and emulsions, where the droplets are highly compressed, as well as\nto dilute suspensions of spherical particles, where the particle separation is\nlarge. In the former limit, Lemlich's result is recovered; in the latter limit,\nMaxwell's result is recovered.",
        "positive": "Lane reduction in driven 2d-colloidal systems through microchannels: The transport behavior of a system of gravitationally driven colloidal\nparticles is investigated. The particle interactions are determined by the\nsuperparamagnetic behavior of the particles. They can thus be arranged in a\ncrystalline order by application of an external magnetic field. Therefore the\nmotion of the particles through a narrow channel occurs in well-defined lanes.\nThe arrangement of the particles is perturbed by diffusion and the motion\ninduced by gravity. Due to these combined influences a density gradient forms\nalong the direction of motion of the particles. A reconfiguration of the\ncrystal is observed leading to a reduction of the number of lanes. In the\ncourse of the lane reduction transition a local melting of the\nquasi-crystalline phase to a disordered phase and a subsequent crystallization\nalong the motion of the particles is observed. This transition is characterized\nexperimentally and using Brownian dynamics (BD) simulations."
    },
    {
        "anchor": "Natural rubber-clay nanocomposites: mechanical and structural properties: The mechanical properties of non-vulcanized natural rubber and dialyzed\nnatural rubber-clay nanocomposites have been studied by uniaxial deformations\nto evaluate the reinforcement efficiency of the clay. We show that while\nnon-rubber molecules contribute to auto-reinforcement, removal of these\nmolecules improves significantly the performance of clay as reinforcement\nagent. These mechanical properties are discussed in relation to morphological\naspects of the clay characterized by TEM and SANS. The nanocomposites prepared\nby \"latex-mixing\" with aqueous dispersions of clay are found to contain\ncompletely exfoliated clay lamellae in coexistence with tactoids. Improved\nmechanical properties of the nanocomposites can be modeled by the high aspect\nratio of exfoliated clay platelets coupled with immobilized rubber matrix.\nInterestingly, presence of tactoids does not appear to compromise the excellent\nreinforcement properties of the exfoliated platelets. At high deformations,\nstrain-induced alignment of the clay exhibits anisotropic scattering, with\nanisotropy increasing with clay concentration and stretching.",
        "positive": "Particle Scale Dynamics in Granular Impact: We perform an experimental study of granular impact, where intruders strike\n2D beds of photoelastic disks from above. High-speed video captures the\nintruder dynamics and the local granular force response, allowing investigation\nof grain-scale mechanisms in this process. We observe rich acoustic behavior at\nthe leading edge of the intruder, strongly fluctuating in space and time, and\nwe show that this acoustic activity controls the intruder deceleration,\nincluding large force fluctuations at short time scales. The average intruder\ndynamics match previous studies using empirical force laws, suggesting a new\nmicroscopic picture, where acoustic energy is carried away and dissipated."
    },
    {
        "anchor": "Transition to the viscoelastic regime in the thinning of polymer\n  solutions: In this study, we investigate the transition between the Newtonian and the\nviscoelastic regimes during the pinch-off of droplets of dilute polymer\nsolutions and discuss its link to the coil-stretch transition. The detachment\nof a drop from a nozzle is associated with the formation of a liquid neck that\ncauses the divergence of the local stress in a vanishingly small region. If the\nliquid is a polymer solution, this increasing stress progressively unwinds the\npolymer chains, up to a point where the resulting increase in the viscosity\nslows down drastically the thinning. This threshold to a viscoelastic behavior\ncorresponds to a macroscopic strain rate $\\dot{\\varepsilon}_{\\rm c}$. In the\npresent study, we characterize the variations of $\\dot{\\varepsilon}_{\\rm c}$\nwith respect to the polymer concentration and molar weight, to the solvent\nviscosity, and to the nozzle size, i.e., the weight of the drop. We provide\nempirical scaling laws for these variations. We also analyze the thinning\ndynamics at the transition and show that it follows a self-similar dynamics\ncontrolled by the time scale ${\\dot{\\varepsilon}_{\\rm c}}^{-1}$. This\ncharacteristic time is different and always shorter than the relaxation time of\nthe polymer.",
        "positive": "Kinetic temperature and pressure of an active Tonks gas: Using computer simulation and analytical theory, we study an active analog of\nthe well-known Tonks gas, where active Brownian particles are confined to a\none-dimensional (1D) channel. By introducing the notion of a kinetic\ntemperature, we derive an accurate analytical expression for the pressure and\nclarify the paradoxical behavior where active Brownian particles confined to 1D\nexhibit anomalous clustering but no motility-induced phase transition. More\ngenerally, this work provides a deeper understanding of pressure in active\nsystems as we uncover a unique link between the kinetic temperature and swim\npressure valid for active Brownian particles in higher dimensions."
    },
    {
        "anchor": "Highly cooperative stress relaxation in two-dimensional soft colloidal\n  crystals: Stress relaxation in crystalline solids is mediated by the formation and\ndiffusion of defects. While it is well established how externally-generated\nstresses relax, through the proliferation and motion of dislocations in the\nlattice, it remains relatively unknown how crystals cope with internal\nstresses. We investigate, both experimentally and in simulations, how highly\nlocalized stresses relax in two-dimensional soft colloidal crystals. When a\nsingle particle is actively excited, by means of optical tweezing, a rich\nvariety of highly collective stress relaxation mechanisms results. These\nmanifest in the form of open strings of cooperatively moving particles through\nthe motion of dissociated vacancy-interstitial pairs, and closed loops of\nmobile particles, which either result from cooperative rotations in transiently\ngenerated circular grain boundaries or through the closure of an open string by\nannihilation of a vacancy-interstitial pair. Surprisingly, we find that the\nsame collective events occur in crystals which are excited by thermal\nfluctuations alone; a large thermal agitation inside the crystal lattice can\ntrigger the irreversible displacements of hundreds of particles. Our results\nillustrate how local stresses can induce large scale cooperative dynamics in\ntwo-dimensional soft colloidal crystals and shed new light on the stabilisation\nmechanisms in ultrasoft crystals.",
        "positive": "The configurational entropy of colloidal particles in a confined space: We calculate the configurational entropy of colloidal particles in a confined\ngeometry interacting as hard disks using Monte Carlo integration method. In\nparticular, we consider systems with three kinds of boundary conditions: hard,\nperiodic and spherical. For small to moderate packing fraction $\\phi$ values,\nwe find the entropies per particle for systems with the periodic and spherical\nboundary conditions tend to reach a same value with the increase of the\nparticle number $N$, while that for the system with the hard boundary\nconditions still has obvious differences compared to them within the studied\n$N$ range. Surprisingly, despite the small system sizes, the estimated\nentropies per particle at infinite system size from extrapolations in the\nperiodic and spherical systems are in reasonable agreement with that calculated\nusing thermodynamic integration method. Besides, as $N$ increases we find the\npair correlation function begins to exhibit similar features as that of a large\nself-assembled system at the same packing fraction. Our findings may contribute\nto a better understanding of how the configurational entropy changes with the\nsystem size and the influence of boundary conditions, and provide insights\nrelevant to engineering particles in confined spaces."
    },
    {
        "anchor": "Anomalous behavior of two-dimensional Hertzian sphere system: The anomalous behavior of a two-dimensional system of Hertzian spheres with\nexponent $\\alpha = 7/2 $ has been studied using the method of molecular\ndynamics. The phase diagram of this system is the melting line of a triangular\ncrystal with several maxima and minima. Water-like density and diffusion\nanomalies have been found in the reentrant melting regions. Noteworthy, a\ndensity anomaly has been observed not only in the liquid and hexatic but also\nsolid phase. The calculations of the phonon spectra of longitudinal and\ntransverse modes have yielded negative dependence of the frequency of\ntransverse modes on density along all directions in the regions with a density\nanomaly. This indicates an association of the density anomaly with transverse\noscillations of the crystal lattice. The regions of density and diffusion\nanomalies have been drawn on the phase diagram. It has been found that the\nstability regions of anomalous diffusion extend to temperatures well above\nmaximum melting point $T = 0.0058$ of the triangular crystal. From analysis of\nthe translational order parameter, which decreases with increasing density in\nthe reentrant melting regions, the presence of a structural anomaly in the\nsystem has been assumed.",
        "positive": "Two-Order-Parameter Description of Liquids: Critical Phenomena and Phase\n  Separation of Supercooled Liquids: Because of the isotropic and disordered nature of liquids, the anisotropy\nhidden in intermolecular interactions are often neglected. Accordingly, the\norder parameter describing a simple liquid has so far been believed to be only\ndensity. In contrast to this common sense, we propose that two order\nparameters, namely, density and bond order parameters, are required to describe\nthe phase behavior of liquids since they intrinsically tend to form local\nbonds. This model gives us clear physical explanations for two\npoorly-understood phenomena in supercooled liquids: (i) large-scale density\nfluctuations and (ii) phase separation of a one-component liquid into two\nliquid phases."
    },
    {
        "anchor": "Anisotropic polymer nanoparticles with controlled dimensions from the\n  morphological transformation of isotropic seeds: Understanding and controlling self-assembly processes at multiple length\nscales is vital if we are to design and create advanced materials. In\nparticular, our ability to organise matter on the nanoscale has advanced\nconsiderably, but still lags far behind our skill in manipulating individual\nmolecules. New tools allowing controlled nanoscale assembly are sorely needed,\nas well as the physical understanding of how they work. Here, we report a new\nmethod for the production of highly anisotropic nanoparticles with controlled\ndimensions based on a morphological transformation process (MORPH for short)\ndriven by the formation of supramolecular bonds. We present a minimal physical\nmodel for MORPH which suggests it will be generalisable to a large number of\npolymer/nanoparticle systems. We envision MORPH becoming a valuable tool for\ncontrolling nanoscale self-assembly, and for the production of functional\nnanostructures for diverse applications.",
        "positive": "Influence of polymer bidispersity on the effective particle-particle\n  interactions in polymer nanocomposites: We investigate the role played by the bidispersity of polymer chains on the\nlocal structure and the potential of mean force (PMF) between silica\nnanoparticles (NPs) in a polystyrene melt. We use the hybrid particle-field\nmolecular dynamics technique which allows to efficiently relax polymer\nnanocomposites even with high molecular weights.The NPs we investigate are\neither bare or grafted with polystyrene chains immersed in a melt of free\npolystyrene chains, whereas the grafted and the free polystyrene chains are\neither monodisperse or bidisperse. The two-body PMF shows that a bidisperse\ndistribution of free polymer chains increases the strength of attraction\nbetween a pair of ungrafted NPs. If the NPs are grafted by polymer chains, the\neffective interaction crucially depends on bidispersity and grafting density of\nthe polymer chains: for low grafting densities, the bidispersity of both free\nand grafted chains increases the repulsion between the NPs, whereas for high\ngrafting densities we observe two different effects. An increase of\nbidispersity in free chains causes the rise of the repulsion between the NPs,\nwhile an increase of bidispersity in grafted chains promotes the rise of\nattraction. Additionally, a proper treatment of multi-body interactions\nimproves the simpler two-body PMF calculations, in both unimodal and bimodal\ncases. We found that, by properly tuning the bidispersity of both free and\ngrafted chains, we can control the structure of the composite materials, which\ncan be confirmed by experimental observations. As a result, the hybrid\nparticle-field approach is confirmed to be a valid tool for reproducing and\npredicting microscopic interactions, which determine the stability of the\nmicroscopic structure of the composite in a wide range of conditions."
    },
    {
        "anchor": "Dewetting of thin films on heterogeneous substrates: Pinning vs.\n  coarsening: We study a model for a thin liquid film dewetting from a periodic\nheterogeneous substrate (template). The amplitude and periodicity of a striped\ntemplate heterogeneity necessary to obtain a stable periodic stripe pattern,\ni.e. pinning, are computed. This requires a stabilization of the longitudinal\nand transversal modes driving the typical coarsening dynamics during dewetting\nof a thin film on a homogeneous substrate. If the heterogeneity has a larger\nspatial period than the critical dewetting mode, weak heterogeneities are\nsufficient for pinning. A large region of coexistence between coarsening\ndynamics and pinning is found.",
        "positive": "Dimensional Analysis Theory and Molecular Dynamics Simulation of\n  Polypropylene Melt Flow during Injection Molding Process: Flow marks are common surface defects that occur in injection-molded\nproducts. Their formation may be related to the flow process of the melt in the\nmold. Through dimensional analysis, we have discovered that the geometric shape\nof the flow field is controlled by specific dimensionless quantities. These\nquantities can be summarized as follows: geometric dimensionless quantities\nrelated to the shape of the mold, material dimensionless quantities related to\nthe melt and mold materials, and physical dimensionless quantities related to\nthe flow. When the geometric shape of the mold changes proportionally, with the\nmelt and mold material fixed, and the initial temperature of the melt and mold\nfixed, the geometric shape of the flow field will be solely controlled by the\nWeissenberg number Wi. If Wi is kept constant, changing the injection speed,\nchanging the relaxation time of the polypropylene melt, or scaling the mold\nwill result in similar geometric shapes of the flow field. If the size of the\nmold is not changed, the geometric shape of the flow field will be the same.\nSince the dimensionless equation represents a similar system of all sizes, we\nverified the above conclusion through molecular dynamics simulations at a\nsmaller scale. After further improvement of the micro simulation system, there\nis a possibility of visualizing the formation process of flow marks. This would\ngreatly aid in the advancement of theory and the elimination of flow marks in\nproduction and experiments. This work also illustrates that the methodology of\ndimensional analysis plus molecular dynamics simulation may be applied to a\nwider range of other systems, scaling down large systems and thus significantly\nreducing their computational effort."
    },
    {
        "anchor": "Avalanches and Structural Change in Cyclically Sheared Silica Glass: We investigate avalanches associated with plastic rearrangements and the\nnature of structural change in the prototypical strong glass, silica,\ncomputationally. Although qualitative aspects of yielding in silica are similar\nto other glasses, we find that the statistics of avalanches exhibits\nnon-trivial behaviour. Investigating the statistics of avalanches and clusters\nin detail, we propose and verify a new relation between exponents\ncharacterizing the size distribution of avalanches and clusters. Across the\nyielding transition, anomalous structural change and densification, associated\nwith a suppression of tetrahedral order, is observed to accompany strain\nlocalisation.",
        "positive": "When Like Destabilizes Like: Inverted Solvent Effects in Apolar\n  Nanoparticle Dispersions: We report on the colloidal stability of nanoparticles with alkanethiol shells\nin apolar solvents. Small angle X-ray scattering and molecular dynamics\nsimulations were used to characterize the interaction between nanoparticles in\nlinear alkane solvents ranging from hexane to hexadecane, including\n\\SI{4}{\\nano\\meter} gold cores with hexadecanethiol shells and\n\\SI{6}{\\nano\\meter} cadmium selenide cores with octadecanethiol shells. We find\nthat the agglomeration is enthalpically driven and that, contrary to what one\nwould expect from classical colloid theory, the temperature at which the\nparticles agglomerate increases with increasing solvent chain length. We\ndemonstrate that the inverted trend correlates with the temperatures at which\nthe ligands order in the different solvents, and show that the inversion is due\nto a combination of enthalpic and entropic effects that enhance the stability\nof the ordered ligand state as the solvent length increases. We also explain\nwhy cyclohexane is a better solvent than hexane, despite having very similar\nsolvation parameters to hexadecane."
    },
    {
        "anchor": "Longitudinal Response of Confined Semiflexible Polymers: The longitudinal response of single semiflexible polymers to sudden changes\nin externally applied forces is known to be controlled by the propagation and\nrelaxation of backbone tension. Under many experimental circumstances,\nrealized, e.g., in nano-fluidic devices or in polymeric networks or solutions,\nthese polymers are effectively confined in a channel- or tube-like geometry. By\nmeans of heuristic scaling laws and rigorous analytical theory, we analyze the\ntension dynamics of confined semiflexible polymers for various generic\nexperimental setups. It turns out that in contrast to the well-known linear\nresponse, the influence of confinement on the non-linear dynamics can largely\nbe described as that of an effective prestress. We also study the free\nrelaxation of an initially confined chain, finding a surprising superlinear\nt^(9/8) growth law for the change in end-to-end distance at short times.",
        "positive": "Influence of surface tension in the surfactant-driven fracture of\n  closely-packed particulate monolayers: A phase-field model is used to capture the surfactant-driven formation of\nfracture patterns in particulate monolayers. The model is intended for the\nregime of closely-packed systems in which the mechanical response of the\nmonolayer can be approximated as a linearly elastic solid. The model\napproximates the loss in tensile strength of the monolayer as the surfactant\nconcentration increases through the evolution of a damage field.\nInitial-boundary value problems are constructed and spatially discretized with\nfinite element approximations to the displacement and surfactant damage fields.\nA comparison between model-based simulations and existing experimental\nobservations indicates a qualitative match in both the fracture patterns and\ntemporal scaling of the fracture process. The importance of surface tension\ndifferences is quantified by means of a dimensionless parameter, revealing\nthresholds that separate different regimes of fracture. These findings are\nsupported by newly performed experiments that validate the model and\ndemonstrate the strong sensitivity of the fracture pattern to differences in\nsurface tension."
    },
    {
        "anchor": "Tuning the Selective Permeability of Polydisperse Polymer Networks: We study the permeability and selectivity (`permselectivity') of model\nmembranes made of polydisperse polymer networks for molecular penetrant\ntransport, using coarse-grained, implicit-solvent computer simulations. The\npermeability $\\mathcal P$ is determined on the linear-response level using the\nsolution-diffusion model, $\\mathcal P = {\\mathcal K}D_\\text{in}$,\n$\\textit{i.e.}$, by calculating the equilibrium penetrant partition ratio\n$\\mathcal K$ and penetrant diffusivity $D_\\text{in}$ inside the membrane. We\nvary two key parameters, namely the monomer-monomer interaction, which controls\nthe degree of swelling and collapse of the network, and the monomer-penetrant\ninteraction, which tunes the penetrant uptake and microscopic energy landscape\nfor diffusive transport. The results for the partition ratio $\\mathcal K$ cover\nfour orders of magnitude and are non-monotonic versus the parameters, which is\nwell interpreted by a second-order virial expansion of the free energy of\ntransferring one penetrant from bulk into the polymeric medium. We find that\nthe penetrant diffusivity $D_\\text{in}$ in the polydisperse networks, in\ncontrast to highly ordered membrane structures, exhibits relatively simple\nexponential decays and obeys well-known free-volume and Kramers' escape scaling\nlaws. The eventually resulting permeability $\\mathcal P$ thus resembles the\nqualitative functional behavior (including maximization and minimization) of\nthe partitioning. However, partitioning and diffusion are anti-correlated,\nyielding large quantitative cancellations, controlled and fine-tuned by the\nnetwork density and interactions as rationalized by our scaling laws. As a\nconsequence, we finally demonstrate that even small changes of\npenetrant-network interactions, $\\textit{e.g.}$, by half a $k_\\text{B}T$,\nmodify the permselectivity of the membrane by almost one order of magnitude.",
        "positive": "Ground State of the Double-Well Condensates Interacting with Trap\n  Oscillations: In the present paper it is shown that the interaction between oscillations of\na double-well trappedcondensate and excited Josephson states corresponding to a\nlarge enough initial disbalance of the particle number generates their bound\nstate. The bound state can realize an absolute minimum of the thermodynamic\nenergy. The existence of the equilibrium bound state implies that the Josephson\nstates can be detected by observing thechange in the condensate shape."
    },
    {
        "anchor": "Note: Relaxation time below jamming: Like other critical phenomena, the jamming transition accompanies the\ndivergence of the relaxation time $\\tau$. A recent numerical study of\nfrictionless spherical particles proves that $\\tau$ is inversely proportional\nto the lowest non-zero eigenvalue $\\lambda_1$ of the dynamical matrix. In this\nnote, we derive the scaling of $\\lambda_1$ below the jamming transition point\n$\\varphi_J$ by solving the linearized dynamical equation. The resultant\ncritical exponent agrees with a previous theoretical result for sheared\nsuspension obtained by applying the virtual work theorem to a simple shear,\nhighlighting the universality of the relaxation dynamics below jamming.",
        "positive": "Aging in Dense Colloids as Diffusion in the Logarithm of Time: The far-from-equilibrium dynamics of glassy systems share important\nphenomenological traits. A transition is generally observed from a\ntime-homogeneous dynamical regime to an aging regime where physical changes\noccur intermittently and, on average, at a decreasing rate. It has been\nsuggested that a global change of the independent time variable to its\nlogarithm may render the aging dynamics homogeneous: for colloids, this entails\ndiffusion but on a logarithmic time scale. Our novel analysis of experimental\ncolloid data confirms that the mean square displacement grows linearly in time\nat low densities and shows that it grows linearly in the logarithm of time at\nhigh densities. Correspondingly, pairs of particles initially in close contact\nsurvive as pairs with a probability which decays exponentially in either time\nor its logarithm. The form of the Probability Density Function of the\ndisplacements shows that long-ranged spatial correlations are very long-lived\nin dense colloids. A phenomenological stochastic model is then introduced which\nrelies on the growth and collapse of strongly correlated clusters (\"dynamic\nheterogeneity\"), and which reproduces the full spectrum of observed colloidal\nbehaviors depending on the form assumed for the probability that a cluster\ncollapses during a Monte Carlo update. In the limit where large clusters\ndominate, the collapse rate is ~1/t, implying a homogeneous, log-Poissonian\nprocess that qualitatively reproduces the experimental results for dense\ncolloids. Finally an analytical toy-model is discussed to elucidate the strong\ndependence of the simulation results on the integrability (or lack thereof) of\nthe cluster collapse probability function."
    },
    {
        "anchor": "Exact expressions for the mobility and electrophoretic mobility of a\n  weakly charged sphere in a simple electrolyte: We present (asymptotically) exact expressions for the mobility and\nelectrophoretic mobility of a weakly charged spherical particle in an $1:1$\nelectrolyte solution. This is done by analytically solving the electro and\nhydrodynamic equations governing the electric potential and fluid flow with\nrespect to an electric field and a nonelectric force. The resulting formulae\nare cumbersome, but fully explicit and trivial for computation. In the case of\na very small particle compared to the Debye screening length ($R \\ll r_D$) our\nresults reproduce proper limits of the classical Debye and Onsager theories,\nwhile in the case of a very large particle ($R \\gg r_D$) we recover, both, the\nnon-monotonous charge dependence discovered by Levich (1958) as well as the\nscaling estimate given by Long, Viovy, and Ajdari (1996), while adding the\npreviously unknown coefficients and corrections. The main applicability\ncondition of our solution is charge smallness in the sense that screening\nremains linear.",
        "positive": "Dynamics of packed swarms: time-displaced correlators of two dimensional\n  incompressible flocks: We analytically calculate the scaling exponents of a two-dimensional KPZ-like\nsystem: coherently moving incompressible polar active fluids. Using three\ndifferent renormalization group approximation schemes, we obtain values for the\n``roughness\" exponent $\\chi$ and anisotropy exponent $\\zeta$ that are extremely\nnear the known exact results. This implies our prediction for the previously\ncompletely unknown dynamic exponent $z$ is quantitatively accurate."
    },
    {
        "anchor": "Isomorph theory of physical aging: This paper derives and discusses the configuration-space Langevin equation\ndescribing a physically aging R-simple system and the corresponding\nSmoluchowski equation. Externally controlled thermodynamic variables like\ntemperature, density, pressure enter the description via the single parameter\n${T}_{\\rm s}/T$ in which $T$ is the bath temperature and ${T}_{\\rm s}$ is the\n\"systemic\" temperature defined at any time $t$ as the thermodynamic equilibrium\ntemperature of the state point with density $\\rho(t)$ and potential energy\n$U(t)$. In equilibrium ${T}_{\\rm s}\\cong T$ with fluctuations that vanish in\nthe thermodynamic limit. In contrast to Tool's fictive temperature and other\neffective temperatures in glass science, the systemic temperature is defined\nfor any configuration with a well-defined density, even if it is not in any\nsense close to equilibrium. Density and systemic temperature define an aging\nphase diagram in which the aging system traces out a curve. Predictions are\ndiscussed for aging following various density-temperature and\npressure-temperature jumps from one equilibrium state to another, as well as\nfor a few other scenarios. The proposed theory implies that R-simple\nglass-forming liquids are characterized by a dynamic Prigogine-Defay ratio of\nunity.",
        "positive": "Peculiarities in the gravitational field of a filamentary ring: The gravitational field of a massive, filamentary ring is considered. We\nprovide an analytic expression for the gravitational potential and demonstrate\nthat the exact gravitational potential and its gradient, thus the gravitational\nforce-field, is not central. Hence it is a good candidate to discuss the\ndifference between the concepts of center of mass and center of gravity. We\nfocus on other consequences of reduced symmetry, e.g., only the $z$-component\nof the angular momentum is conserved. However, the remnant high symmetry of\nthis system also ensures that there are special classes of motions which are\nrestricted to invariant subspaces, thus, depending on the initial condition,\nthe dynamics of a point particle is integrable. We also show that periodic\norbits in the equatorial plane external to the ring are possible, but only if\nthe angular momentum is above a threshold value. In this case the orbits are\nstable."
    },
    {
        "anchor": "Electro-Osmotic Flow of Semidilute Polyelectrolyte Solutions: We investigate electro-osmosis in aqueous solutions of polyelectrolytes using\nmean-field equations. A solution of positively charged polyelectrolytes is\nconfined between two negatively charged planar surfaces, and an electric field\nis applied parallel to the surfaces. When electrostatic attraction between the\npolymer and the surface is strong, the polymers adhere to the surface, forming\na highly viscous adsorption layer that greatly suppresses the electro-osmosis.\nConversely, electro-osmosis is enhanced by depleting the polymers from the\nsurfaces. We also found that the electro-osmotic flow is invertible when the\nelectrostatic potential decays to its bulk value with the opposite sign. These\nbehaviors are well explained by a simple mathematical form of the\nelectro-osmotic coefficient.",
        "positive": "Phase diagram of thick ribbons in a bad solvent: Ribbons are topological objects of biological and technological importance.\nHere, we study the folding of thick ribbons with hydrophobic surfaces in a bad\nsolvent in regimes in which either the ribbon's thickness or the solvent\nmolecule size is not vanishingly small compared to the ribbon's width.\nExtensive Monte Carlo simulations show that ribbons of various lengths and with\na small stiffness adopt several distinct configurations as the ground state\nthat include rolled (Archimedean spiral), curled, twisted and globule\nconformations. Analytic and numerical calculations based on the consideration\nof putative ground states lead to phase diagrams that qualitatively agree with\nthe simulation results. A symmetry breaking of the planar rolled configuration\nin favor of the elongated twisted and the globular ribbons is observed on\nincreasing the solvent size. Interestingly, the twisted ribbon is found as the\nground state in the absence of any energetic preference for twisting. We show\nthat the twist of the DNA double helix structure can be stabilized when modeled\nas a hydrophobic thick ribbon even in the limit of vanishing solvent size."
    },
    {
        "anchor": "Polymer Translocation Dynamics in the Quasi-Static Limit: Monte Carlo (MC) simulations are used to study the dynamics of polymer\ntranslocation through a nanopore in the limit where the translocation rate is\nsufficiently slow that the polymer maintains a state of conformational\nquasi-equilibrium. The system is modeled as a flexible hard-sphere chain that\ntranslocates through a cylindrical hole in a hard flat wall. In some\ncalculations, the nanopore is connected at one end to a spherical cavity.\nTranslocation times are measured directly using MC dynamics simulations. For\nsufficiently narrow pores, translocation is sufficiently slow that the mean\ntranslocation time scales with polymer length N according to <\\tau> \\propto\n(N-N_p)^2, where N_p is the average number of monomers in the nanopore; this\nscaling is an indication of a quasi-static regime in which polymer-nanopore\nfriction dominates. We use a multiple-histogram method to calculate the\nvariation of the free energy with Q, a coordinate used to quantify the degree\nof translocation. The free energy functions are used with the Fokker-Planck\nformalism to calculate translocation time distributions in the quasi-static\nregime. These calculations also require a friction coefficient, characterized\nby a quantity N_{eff}, the effective number of monomers whose dynamics are\naffected by the confinement of the nanopore. This was determined by fixing the\nmean of the theoretical distribution to that of the distribution obtained from\nMC dynamics simulations. The theoretical distributions are in excellent\nquantitative agreement with the distributions obtained directly by the MC\ndynamics simulations for physically meaningful values of N_{eff}. The free\nenergy functions for narrow-pore systems exhibit oscillations with an amplitude\nthat is sensitive to the nanopore length. Generally, larger oscillation\namplitudes correspond to longer translocation times.",
        "positive": "Active Fusion and Fission Processes on a Fluid Membrane: We investigate the steady states and dynamical instabilities resulting from\n``particles'' depositing on (fusion) and pinching off (fission) a fluid\nmembrane. These particles could be either small lipid vesicles or isolated\nproteins. In the stable case, such fusion/fission events suppress long\nwavelength fluctuations of the membrane. In the unstable case, the membrane\nshoots out long tubular structures reminiscent of endosomal compartments or\nfolded structures as in internal membranes like the endoplasmic reticulum or\nGolgi. We argue that these fusion/fission events should be strongly affected by\ntension."
    },
    {
        "anchor": "Impact of single-particle compressibility on the fluid-solid phase\n  transition for ionic microgel suspensions: We study ionic microgel suspensions composed of swollen particles for various\nsingle-particle stiffnesses. We measure the osmotic pressure $\\pi$ of these\nsuspensions and show that it is dominated by the contribution of free ions in\nsolution. As this ionic osmotic pressure depends on the volume fraction of the\nsuspension $\\phi$, we can determine $\\phi$ from $\\pi$, even at volume fractions\nso high that the microgel particles are compressed. We find that the width of\nthe fluid-solid phase coexistence, measured using $\\phi$, is larger than its\nhard-sphere value for the stiffer microgels that we study and progressively\ndecreases for softer microgels. For sufficiently soft microgels, the\nsuspensions are fluid-like, irrespective of volume fraction. By calculating the\ndependence on $\\phi$ of the mean volume of a microgel particle, we show that\nthe behavior of the phase-coexistence width correlates with whether or not the\nmicrogel particles are compressed at the volume fractions corresponding to\nfluid-solid coexistence.",
        "positive": "Traveling band formation in feedback-driven colloids: Using simulation and theory we study the dynamics of a colloidal suspension\nin two dimensions subject to a time-delayed repulsive feedback that depends on\nthe positions of the colloidal particles. The colloidal particles experience an\nadditional potential that is a superposition of repulsive potential energies\ncentered around the positions of all the particles a delay time ago. Here we\nshow that such a feedback leads to self-organization of the particles into\ntraveling bands. The width of the bands and their propagation speed can be\ntuned by the delay time and the range of the imposed repulsive potential. The\nemerging traveling band behavior is observed in Brownian dynamics computer\nsimulations as well as microscopic dynamic density functional theory (DDFT).\nTraveling band formation also persists in systems of finite size leading, in\nthe case of circularly confined systems, to rotating traveling waves."
    },
    {
        "anchor": "Mapping the jamming transition of bidisperse mixtures: We systematically map out the jamming transition of all 2D bidisperse\nmixtures of frictionless disks in the hard particle limit. The critical volume\nfraction, mean coordination number, number of rattlers, structural order\nparameters, and bulk modulus each show a rich variation with mixture\ncomposition and particle size ratio, and can therefore be tuned by choosing\ncertain mixtures. We identify two local minima in the critical volume fraction,\nboth of which have low structural order; one minimum is close to the widely\nstudied 50:50 mixture of particles with a ratio of radii of 1:1.4. We also\nidentify a region at low size ratios characterized by increased structural\norder and high rattler fractions, with a corresponding enhancement in the\nstiffness.",
        "positive": "Force chains and networks: wet suspensions through dry granular eyes: Recent advances in shear-thickening suspension rheology suggest a relation\nbetween (wet) suspension flow below jamming and (dry) granular physics. To\nprobe this connection, we simulated the contact force networks in suspensions\nof non-Brownian spheres using the discrete element method (DEM), varying the\nparticle friction coefficient and volume fraction. We find that force networks\nin these suspensions show quantitative similarities to those in jammed dry\ngrains. As suspensions approach the jamming point, the extrapolated volume\nfraction and coordination number at jamming are similar to critical values\nobtained for isotropically compressed spheres. Similarly, the shape of the\ndistribution of contact forces in flowing suspensions is remarkably similar to\nthat found in granular packings, suggesting potential refinements for\nanalytical mean field models for the rheology of shear thickening suspensions."
    },
    {
        "anchor": "Transport of overdamped Brownian particles in a two-dimensional tube:\n  Nonadiabatic regime: Transport of overdamped Brownian particles in a two-dimensional asymmetric\ntube is investigated in the presence of nonadiabatic periodic driving forces.\nBy using Brownian dynamics simulations we can find that the phenomena in\nnonadiabatic regime differ from that in adiabatic case. The direction of the\ncurrent can be reversed by tuning the driving frequency. Remarkably, the\ncurrent as a function of the driving amplitude exhibits several local maxima at\nfinite driving frequency.",
        "positive": "Flexoelectricity and the Entropic Force between Fluctuating Fluid\n  Membranes: Biological membranes undergo noticeable thermal fluctuations at physiological\ntemperatures. When two membranes approach each other, they hinder the out of\nplane fluctuations of the other. This hindrance leads to an entropic repulsive\nforce between membranes which, in an interplay with attractive and repulsive\nforces due to other sources, impacts a range of biological functions: cell\nadhesion, membrane fusion, self-assembly, binding-unbinding transition among\nothers. In this work, we take cognizance of the fact that biological membranes\nare not purely mechanical entities and, due to the phenomenon of\nflexoelectricity, exhibit a coupling between deformation and electric\npolarization. The ensuing coupled mechanics-electrostatics-statistical\nmechanics problem is analytically intractable. We use a variational\nperturbation method to analyze, in closed-form, the contribution of\nflexoelectricity to the entropic force between two fluctuating membranes and\ndiscuss its possible physical implications. We find that flexoelectricity leads\nto a correction that switches from an enhanced attraction at close membrane\nseparations and an enhanced repulsion when the membranes are further apart."
    },
    {
        "anchor": "Geodesics around line defects in elastic solids: Topological defects in solids, usually described by complicated boundary\nconditions in elastic theory, may be described more simply as sources of a\ngravity- like deformation field in the geometric approach of Katanaev and\nVolovich. This way, the deformation field is described by non-Euclidean metric\nthat incorporates the boundary imposed by the defects. A possible way of\ngaining some insight into the motion of particles in a medium with topological\ndefects (e.g., electrons in a dislocated metal) is to look at the geodesics of\nthe medium around the defect. In this work, we find the exact solution for the\ngeodesic equation for elastic medium with a generic line defect, the\ndispiration, that can either be a screw dislocation or a wedge disclination for\nparticular choices of its parameters.",
        "positive": "Phase boundaries, nucleation rates and speed of crystal growth of the\n  water-to-ice transition under an electric field: a simulation study: We investigate with computer simulations the effect of applying an electric\nfield on the water-to-ice transition. We use a combination of state-of-the-art\nsimulation techniques to obtain phase boundaries and crystal growth rates\n(direct coexistence), nucleation rates (seeding) and interfacial free energies\n(seeding and mold integration). First, we consider ice Ih, the most stable\npolymorph in the absence of a field. Its normal melting temperature, speed of\ncrystal growth and nucleation rate (for a given supercooling) diminish as the\nintensity of the field goes up. Then, we study polarised cubic ice, or ice Icf,\nthe most stable solid phase under a strong electric field. Its normal melting\npoint goes up with the field and, for a given supercooling, under the studied\nfield (0.3 V/nm) ice Icf nucleates and grows at a similar rate as Ih with no\nfield. The net effect of the field would be then that ice nucleates at warmer\ntemperatures, but in the form of ice Icf. The main conclusion of this work is\nthat reasonable electric fields (not strong enough to break water molecules\napart) are not relevant in the context of homogeneous ice nucleation at 1 bar."
    },
    {
        "anchor": "Let's deflate that beach ball: We investigate the relationship between pre-buckling and post-buckling states\nas a function of shell properties, within the deflation process of shells of an\nisotropic material. With an original and low-cost set-up that allows to measure\nsimultaneously volume and pressure, elastic shells whose relative thicknesses\nspan on a broad range are deflated until they buckle. We characterize the\npost-buckling state in the pressure-volume diagram, but also the relaxation\ntoward this state. The main result is that before as well as after the\nbuckling, the shells behave in a way compatible with predictions generated\nthrough thin shell assumption, and that this consistency persists for shells\nwhere the thickness reaches up to 0.3 the shell's midsurface radius.",
        "positive": "Impedance of the free surface of liquid electrolytes: A possibility for the observation of so-called structure resonances (SR) in\nelectrolytes arising due to relative motion of the cluster charged nucleus and\nits solvation shell is demonstrated. The discussed method considers the\nresonant contribution of the SR to the frequency dependence of the reflection\n(transmission) coefficient of the electromagnetic wave interacting with the\nfree electrolyte surface. Of special interest is the observation of SR for\nmultiply charged particles in electrolyte providing direct information on the\ncharge of single cluster. Also important are other not so prominent details of\nthe wave interaction with mobile charged clusters in electrolyte related to the\nformation and complicated nature of the frequency dependence of the charged\ncluster associated mass."
    },
    {
        "anchor": "Dewetting of thin polymer films: Influence of interface evolution: The dewetting dynamics of ultrathin polymer films, e.g. in the model system\nof polystyrene on a polydimethylsiloxane-covered substrate, exhibits\ninteresting behavior like a fast decay of the dewetting velocity and a maximum\nin the width of the built-up rim in the course of time. These features have\nbeen recently ascribed to the relaxation of residual stresses in the film that\nstem from the nonequilibrium preparation of the samples. Recent experiments by\nCoppee et al. on PS with low molecular weight, where such stresses could not be\nevidenced, showed however similar behavior. By scaling arguments and numerical\nsolution of a thin film viscoelastic model we show that the maximum in the\nwidth of the rim can be caused by a temporal evolution of the friction\ncoefficient (or equivalently of the slip length), for which we discuss two\npossible mechanisms. In addition, the maximum in the width is affected by the\nsample age. As a consequence, knowing the temporal behavior of friction (or\nslip length) in principle allows to measure the aging dynamics of a\npolymer-polymer interface by simple dewetting experiments.",
        "positive": "Bacterial Motility Enhances Adhesion to Oil Droplets: Adhesion of bacteria to liquid-liquid interfaces can play a role in the\nbiodegradation of dispersed hydrocarbons and in biochemical and bioprocess\nengineering. Whereas thermodynamic factors underpinning adhesion are well\nstudied, the role of bacterial activity on adhesion is less explored.Here, we\nshow that bacterial motility enhances adhesion to surfactant-decorated oil\ndroplets dispersed in artificial sea water. Motile Halomonas titanicae adhered\nto hexadecane droplets stabilized with dioctyl sodium sulfosuccinate (DOSS)\nmore rapidly and at greater surface densities compared to nonmotile H.\ntitanicae, whose flagellar motion was arrested through addition of a pro-ton\nuncoupler. Increasing the concentration of DOSS reduced the surface density of\nboth motile and nonmotile bacteria as a result of the reduced interfacial\ntension."
    },
    {
        "anchor": "Modeling Defects, Shape Evolution, and Programmed Auto-origami in Liquid\n  Crystal Elastomers: Liquid crystal elastomers represent a novel class of programmable\nshape-transforming materials whose shape change trajectory is encoded in the\nmaterial's nematic director field. Using three-dimensional nonlinear finite\nelement elastodynamics simulation, we model a variety of different actuation\ngeometries and device designs: thin films containing topological defects,\npatterns that induce formation of folds and twists, and a bas-relief structure.\nThe inclusion of finite bending energy in the simulation model reveals features\nof actuation trajectory that may be absent when bending energy is neglected. We\nexamine geometries with a director pattern uniform through the film thickness\nencoding multiple regions of positive Gaussian curvature. Simulations indicate\nthat heating such a system uniformly produces a disordered state with curved\nregions emerging randomly in both directions due to the film's up-down\nsymmetry. By contrast, applying a thermal gradient by heating the material\nfirst on one side breaks up-down symmetry and results in a deterministic\ntrajectory producing a more ordered final shape. We demonstrate that a folding\nzone design containing cut-out areas accommodates transverse displacements\nwithout warping or buckling; and demonstrate that bas-relief and more complex\nbent-twisted structures can be assembled by combining simple design motifs.",
        "positive": "Model for the Scaling of Stresses and Fluctuations in Flows near Jamming: We probe flows of soft, viscous spheres near the jamming point, which acts as\na critical point for static soft spheres. Starting from energy considerations,\nwe find nontrivial scaling of velocity fluctuations with strain rate. Combining\nthis scaling with insights from jamming, we arrive at an analytical model that\npredicts four distinct regimes of flow, each characterized by rational-valued\nscaling exponents. Both the number of regimes and values of the exponents\ndepart from prior results. We validate predictions of the model with\nsimulations."
    },
    {
        "anchor": "Peptide pores in lipid bilayers : voltage facilitation pleads for a\n  revised model: We address the problem of antimicrobial peptides that create pores in lipid\nbilayers, focusing on voltage-temperature dependence of pore opening. Two novel\nexperiments (voltage-clamp with alamethicin as an emblematic representative of\nthese peptides and neutron reflectivity of lipid-monolayer at solid/water\ninterface under electric field) serve to revise the only current theoretical\nmodel (H. W. Huang et al.Phys. Rev. Lett., 92, 198304 (2004)). We introduce a\ngeneral contribution of the electric field as being responsible for an\nunbalanced tension of the two bilayer leaflets and we claim that the main\nentropy cost of one pore opening is due to the corresponding \"excluded-area\"\nfor lipid translation.",
        "positive": "Connecting glass-forming ability of binary mixtures of soft particles to\n  equilibrium melting temperatures: The glass-forming ability is an important material property for manufacturing\nglasses and understanding the long-standing glass transition problem. Because\nof the nonequilibrium nature, it is difficult to develop the theory for it.\nHere we report that the glass-forming ability of binary mixtures of soft\nparticles is related to the equilibrium melting temperatures. Due to the\ndistinction in particle size or stiffness, the two components in a mixture\neffectively feel different melting temperatures, leading to a melting\ntemperature gap. By varying the particle size, stiffness, and composition over\na wide range of pressures, we establish a comprehensive picture for the\nglass-forming ability, based on our finding of the direct link between the\nglass-forming ability and the melting temperature gap. Our study reveals and\nexplains the pressure and interaction dependence of the glass-forming ability\nof model glass-formers, and suggests strategies to optimize the glass-forming\nability via the manipulation of particle interactions."
    },
    {
        "anchor": "Interfacial tension and a three-phase generalized self-consistent theory\n  of non-dilute soft composite solids: In the dilute limit Eshelby's inclusion theory captures the behavior of a\nwide range of systems and properties. However, because Eshelby's approach\nneglects interfacial stress, it breaks down in soft materials as the inclusion\nsize approaches the elastocapillarity length $L$. Here, we use a three-phase\ngeneralized self-consistent method to calculate the elastic moduli of\ncomposites comprised of an isotropic, linear-elastic compliant solid hosting a\nspatially random monodisperse distribution of spherical liquid droplets. As\nopposed to similar approaches, we explicitly capture the liquid-solid\ninterfacial stress when it is treated as an isotropic, strain-independent\nsurface tension. Within this framework, the composite stiffness depends solely\non the ratio of the elastocapillarity length $L$ to the inclusion radius $R$.\nIndependent of inclusion volume fraction, we find that the composite is\nstiffened by the inclusions whenever $R < 3L/2$. Over the same range of\nparameters, we compare our results with alternative approaches (dilute and\nMori-Tanaka theories that include surface tension). Our framework can be easily\nextended to calculate the composite properties of more general soft materials\nwhere surface tension plays a role.",
        "positive": "Tensile Forces and Shape Entropy Explain Observed Crista Structure in\n  Mitochondria: A model is presented from which the observed morphology of the inner\nmitochondrial membrane can be inferred as minimizing the system's free energy.\nBesides the usual energetic terms for bending, surface area, and pressure\ndifference, our free energy includes terms for tension that we believe to be\nexerted by proteins and for an entropic contribution due to many dimensions\nworth of shapes available at a given energy.\n  In order to test the model, we measured the structural features of\nmitochondria in HeLa cells and mouse embryonic fibroblasts using 3D electron\ntomography. Such tomograms reveal that the inner membrane self-assembles into a\ncomplex structure that contains both tubular and flat lamellar crista\ncomponents. This structure, which contains one matrix compartment, is believed\nto be essential to the proper functioning of mitochondria as the powerhouse of\nthe cell. We find that tensile forces of the order of 10 pN are required to\nstabilize a stress-induced coexistence of tubular and flat lamellar cristae\nphases. The model also predicts \\Deltap = -0.036 \\pm 0.004 atm and \\sigma=0.09\n\\pm 0.04 pN/nm."
    },
    {
        "anchor": "Conformations and diffusion of flexibly linked colloidal chains: For biologically relevant macromolecules such as intrinsically disordered\nproteins, internal degrees of freedom that allow for shape changes have a large\ninfluence on both the motion and function of the compound. A detailed\nunderstanding of the effect of flexibility is needed in order to explain their\nbehavior. Here, we study a model system of freely-jointed chains of three to\nsix colloidal spheres, using both simulations and experiments. We find that in\nspite of their short lengths, their conformational statistics are well\ndescribed by two-dimensional Flory theory, while their average translational\nand rotational diffusivity follow the Kirkwood-Riseman scaling. Their maximum\nflexibility does not depend on the length of the chain, but is determined by\nthe near-wall in-plane translational diffusion coefficient of an individual\nsphere. Furthermore, we uncover shape-dependent effects in the short-time\ndiffusivity of colloidal tetramer chains, as well as non-zero couplings between\nthe different diffusive modes. Our findings may have implications for\nunderstanding both the diffusive behavior and the most likely conformations of\nmacromolecular systems in biology and industry, such as proteins, polymers,\nsingle-stranded DNA and other chain-like molecules.",
        "positive": "Soft glassy materials with tunable extensibility: Extensibility is beyond the paradigm of classical soft glassy materials, and\nmore broadly, yield-stress fluids. Recently, model yield-stress fluids with\nsignificant extensibility have been designed by adding polymeric phases to\nclassically viscoplastic dispersions [1, 2, 3]. However, fundamental questions\nremain about the design of and coupling between the shear and extensional\nrheology of such systems. In this work, we propose a model material, a mixture\nof soft glassy microgels and solutions of high molecular weight linear\npolymers. We establish systematic criteria for the design and thorough\nrheological characterization of such systems, both in shear and in extension.\nUsing our material, we show that it is possible to dramatically change the\nbehavior in extension with minimal change in the shear yield stress and elastic\nmodulus, thus enabling applications that exploit orthogonal modulation of shear\nand extensional material properties."
    },
    {
        "anchor": "Water-like Anomalies and Breakdown of the Rosenfeld Excess Entropy\n  Scaling Relations for the Core-Softened Systems: Dependence on the Trajectory\n  in Density-Temperature Plane: We show that the existence of the water-like anomalies in kinetic\ncoefficients in the core-softened systems depends on the trajectory in $\\rho-T$\nplane along which the kinetic coefficients are calculated. In particular, it is\nshown that the diffusion anomaly does exist along the isotherms, but disappears\nalong the isochores. We analyze the applicability of the Rosenfeld entropy\nscaling relations to the systems with the core-softened potentials\ndemonstrating the water-like anomalies. It is shown that the validity of the of\nRosenfeld scaling relation for the diffusion coefficient also depends on the\ntrajectory in the $\\rho-T$ plane along which the kinetic coefficients and the\nexcess entropy are calculated. In particular, it is valid along isochors, but\nit breaks down along isotherms.",
        "positive": "Heat capacity at the glass transition: A fundamental problem of glass transition is to explain the jump of heat\ncapacity at the glass transition temperature $T_g$ without asserting the\nexistence of a distinct solid glass phase. This problem is also common to other\ndisordered systems, including spin glasses. We propose that if $T_g$ is defined\nas the temperature at which the liquid stops relaxing at the experimental time\nscale, the jump of heat capacity at $T_g$ follows as a necessary consequence\ndue to the change of system's elastic, vibrational and thermal properties. In\nthis picture, we discuss time-dependent effects of glass transition, and\nidentify three distinct regimes of relaxation. Our approach explains widely\nobserved logarithmic increase of $T_g$ with the quench rate and the correlation\nof heat capacity jump with liquid fragility."
    },
    {
        "anchor": "Temporal response to harmonic driving in electroconvection: The temporal evolution of the spatially periodic electroconvection (EC)\npatterns has been studied within the period of the driving ac voltage by\nmonitoring the light intensity diffracted from the pattern. Measurements have\nbeen carried out on a variety of nematic systems, including those with negative\ndielectric and positive conductivity anisotropy, exhibiting \"standard EC\"\n(s-EC), those with both anisotropies negative exhibiting \"non-standard EC\"\n(ns-EC), as well as those with the two anisotropies positive. Theoretical\npredictions have been confirmed for stationary s-EC and ns-EC patterns.\nTransitions with Hopf bifurcation have also been studied. While traveling had\nno effect on the temporal evolution of dielectric s-EC, traveling conductive\ns-EC and ns-EC patterns exhibited a substantially altered temporal behavior\nwith a dependence on the Hopf frequency. It has also been shown that in\nnematics with both anisotropies positive, the pattern develops and decays\nwithin an interval much shorter than the period, even at relatively large\ndriving frequencies.",
        "positive": "Confinement induced three-dimensional trajectories of microswimmers in\n  rectangular channels: We study the trajectories of a model microorganism inside three-dimensional\nchannels with square and rectangular cross-sections. Using (i) numerical\nsimulations based on lattice-Boltzmann method, and (ii) analytical expressions\nusing far-field hydrodynamic approximations and method of images we\nsystematically investigate the role of the strength and finite-size of the\nsquirmer, confinement dimensions, and initial conditions in determining the\nthree dimensional trajectories of microswimmers. Our results indicate that the\nhydrodynamic interactions with the confining walls of the channel significantly\naffect the swimming speed and trajectory of the model microswimmer.\nSpecifically, pullers always display sliding motion inside the channel: weak\npullers slide through the channel centerline, while strong pullers slide\nthrough a path close to any of the walls. Pushers generally follow helical\nmotion in a square channel. Unlike pullers and pushers, the trajectories of\nneutral swimmers are not easy to generalize, and are sensitive to the initial\nconditions. Despite this diversity in the trajectories, the far-field\nexpressions capture the essential features of channel-confined swimmers.\nFinally, we propose a method based on the principle of superposition to\nunderstand the origin of the three-dimensional trajectories of channel confined\nswimmers. Such construction allows us to predict and justify the origin of\napparently complex 3D trajectories generated by different types of swimmers in\nchannels with square and rectangular cross sections."
    },
    {
        "anchor": "Unstable Flow and Non-Monotonic Constitutive Equation of Transient\n  Networks: We have measured the nonlinear rheological response of a model transient\nnetwork over a large range of steady shear rates. The system is built up from\nan oil in water droplet microemulsion into which a telechelic polymer is\nincorporated. The phase behaviour is characterized which comprises a liquid-gas\nphase separation and a percolation threshold. The rheological measurements are\nperformed in the one phase region above the percolation line. Shear thinning is\nobserved for all samples, leading in most cases to an unstable stress response\nat intermediate shear rates. We built up a very simple mean field model which\ninvolves the reduction of the residence time of the stickers in the droplets\ndue to the chain tensions at high shear. The computed constitutive equation is\nnon-monotonic with a range where the stress is a decreasing function of the\nrate, a feature that indeed makes homogeneous flows unstable. The computed the\nflow curves compare well to the experiments.",
        "positive": "Isobaric first-principles molecular dynamics of liquid water with\n  nonlocal van der Waals interactions: We investigate the structural properties of liquid water at near ambient\nconditions using first-principles molecular dynamics simulations based on a\nsemilocal density functional augmented with nonlocal van der Waals\ninteractions. The adopted scheme offers the advantage of simulating liquid\nwater at essentially the same computational cost of standard semilocal\nfunctionals. Applied to the water dimer and to ice Ih, we find that the\nhydrogen-bond energy is only slightly enhanced compared to a standard semilocal\nfunctional. We simulate liquid water through molecular dynamics in the NpH\nstatistical ensemble allowing for fluctuations of the system density. The\nstructure of the liquid departs from that found with a semilocal functional\nleading to more compact structural arrangements. This indicates that the\ndirectionality of the hydrogen-bond interaction has a diminished role as\ncompared to the overall attractions, as expected when dispersion interactions\nare accounted for. This is substantiated through a detailed analysis comprising\nthe study of the partial radial distribution functions, various local order\nindices, the hydrogen-bond network, and the selfdiffusion coefficient. The\nexplicit treatment of the van der Waals interactions leads to an overall\nimproved description of liquid water."
    },
    {
        "anchor": "Surface coupling effect on wetting and layering transitions: The effect of the surface coupling $J_s$ on the dependency of the layering\ntransition temperature $T_L$ as a function of the thickness $N$, of a spin-1/2\nIsing film, is studied using the mean field theory. It is found that for $J_s$\ngreater than a critical value ($J_{sc}=1.30$), the layering transition\ntemperature decreases when the film thickness $N$ increases for any values of\nthe surface magnetic field $H_s$. While, for $J_s < J_{sc}$, the behaviour of\nthe layering transition temperature $T_L$, as a function of $N$, depends\nstrongly on the values of $H_s$. Indeed, we show the existence of three\ndistinct behaviours of $T_L$, as a function of the film thickness $N$,\nseparated by two critical surface magnetic fields $H_{sc1}$ and $H_{sc2}$,\nnamely: $(i)$ for $H_s < H_{sc1}$, $T_L$ increases with $N$; $(ii)$ for\n$H_{sc1} < H_s < H_{sc2}$, $T_L$ increases for small values of $N$, and\ndecreases for large value ones; (iii) while for $H_s > H_{sc2}$, $T_L$\ndecreases with increasing the film thickness. Furthermore, depending on the\nvalues of $J_s$, the wetting temperature $T_w (T_w=T_L$ when $N \\to \\infty$ for\na given material), can be greater or smaller than the layering transition\ntemperature of a film of thickness $N$ of the same material.",
        "positive": "Phase Transformations in Binary Colloidal Monolayers: Phase transformations can be difficult to characterize at the microscopic\nlevel due to the inability to directly observe individual atomic motions. Model\ncolloidal systems, by contrast, permit the direct observation of individual\nparticle dynamics and of collective rearrangements, which allows for real-space\ncharacterization of phase transitions. Here, we study a quasi-two-dimensional,\nbinary colloidal alloy that exhibits liquid-solid and solid-solid phase\ntransitions, focusing on the kinetics of a diffusionless transformation between\ntwo crystal phases. Experiments are conducted on a monolayer of magnetic and\nnonmagnetic spheres suspended in a thin layer of ferrofluid and exposed to a\ntunable magnetic field. A theoretical model of hard spheres with point dipoles\nat their centers is used to guide the choice of experimental parameters and\ncharacterize the underlying materials physics. When the applied field is normal\nto the fluid layer, a checkerboard crystal forms; when the angle between the\nfield and the normal is sufficiently large, a striped crystal assembles. As the\nfield is slowly tilted away from the normal, we find that the transformation\npathway between the two phases depends strongly on crystal orientation, field\nstrength, and degree of confinement of the monolayer. In some cases, the\npathway occurs by smooth magnetostrictive shear, while in others it involves\nthe sudden formation of martensitic plates."
    },
    {
        "anchor": "Dynamics of individual Brownian rods in a microchannel flow: We study the orientational dynamics of heavy silica microrods flowing through\na microfluidic channel. Comparing experiments and Brownian dynamics simulations\nwe identify different particle orbits, in particular in-plane tumbling\nbehavior, which cannot be explained by classical Jeffery theory, and we relate\nthis behavior to the rotational diffusion of the rods. By constructing the\nfull, three-dimensional, orientation distribution, we describe the rod\ntrajectories and quantify the persistence of Jeffery orbits using temporal\ncorrelation functions of the Jeffery constant. We find that our colloidal rods\nlose memory of their initial configuration in about a second, corresponding to\nhalf a Jeffery period.",
        "positive": "Two step micro-rheological behavior in a viscoelastic fluid: We perform micro-rheological experiments with a colloidal bead driven through\na viscoelastic worm-like micellar fluid and observe two distinctive shear\nthinning regimes, each of them displaying a Newtonian-like plateau. The shear\nthinning behavior at larger velocities is in qualitative agreement with\nmacroscopic rheological experiments. The second process, observed at\nWeissenberg numbers as small as a few percent, appears to have no analog in\nmacro rheological findings. A simple model introduced earlier captures the\nobserved behavior, and implies that the two shear thinning processes correspond\nto two different length scales in the fluid. This model also reproduces\noscillations which have been observed in this system previously. While the\nsystem under macro-shear seems to be near equilibrium for shear rates in the\nregime of the intermediate Newtonian-like plateau, the one under micro-shear is\nthus still far from it. The analysis suggests the existence of a length scale\nof a few micrometres, the nature of which remains elusive."
    },
    {
        "anchor": "Bulk-like viscosity and shear thinning during dynamic compression of a\n  nanoconfined liquid: The viscosity of liquids under nanoconfinement remains controversial. Reports\nrange from spontaneous solidification to no change in the viscosity at all.\nHere, we present thorough measurements with a small-amplitude linear atomic\nforce microscopy technique and careful consideration of the confinement\ngeometry, to show that in a weakly interacting liquid, average viscosity\nremains bulk like, except for strong shear thinning once the liquid is confined\nto less than four molecular layers. Overlaid over this bulk-like viscous\nbehavior are stiffness and damping oscillations, indicating non-continuum\nbehavior, as well as an elastic response when the liquid is allowed to order in\nthe confinement gap.",
        "positive": "Strain-Induced Violation of Temperature Uniformity in Mesoscale Liquids: Thermo-elasticity couples the deformation of an elastic (solid) body to its\ntemperature and vice-versa. It is a solid-like property. Highlighting such\nproperty in liquids is a paradigm shift: it requires long-range collective\ninteractions that are not considered in current liquid descriptions. The\npresent pioneering microthermal studies provide evidence for such solid-like\ncorrelations. It is shown that ordinary liquids emit a modulated thermal signal\nwhen applying a low frequency (Hz) mechanical shear stress. The liquid splits\nin several tenths microns wide thermal bands, all varying synchronously and\nseparately with the applied stress wave reaching a sizable amplitude of $\\pm$\n0.2 {\\deg}C. This thermal property is unknown in liquids. Thermo-mechanical\ncoupling challenges a dogma in fluid dynamics: the liquid responds\ncollectively, adapts its internal energy to external shear strain and is not\ngoverned by short relaxation times responsible of instant thermal dissipation.\nThe proof of thermomechanical coupling opens the way to a new generation of\nenergy-efficient temperature converters."
    },
    {
        "anchor": "Detachment of semiflexible polymer chains from a substrate - a Molecular\n  Dynamics investigation: Using Molecular Dynamics simulations, we study the force-induced detachment\nof a coarse-grained model polymer chain from an adhesive substrate. One of the\nchain ends is thereby pulled at constant speed off the attractive substrate and\nthe resulting saw-tooth profile of the measured mean force $< f >$ vs height\n$D$ of the end-segment over the plane is analyzed for a broad variety of\nparameters. It is shown that the observed characteristic oscillations in the $<\nf >$-$D$ profile depend on the bending and not on the torsional stiffness of\nthe detached chains. Allowing for the presence of hydrodynamic interactions\n(HI) in a setup with explicit solvent and DPD-thermostat, rather than the case\nof Langevin thermostat, one finds that HI have little effect on the $< f >$-$D$\nprofile. Also the change of substrate affinity with respect to the solvent from\nsolvophilic to solvophobic is found to play negligible role in the desorption\nprocess. In contrast, a changing ratio $\\epsilon_s^A / \\epsilon_s^B$ of the\nbinding energies of $A$- and $B$-segments in the detachment of an\n$AB$-copolymer from adhesive surface strongly changes the $< f >$-$D$ profile\nwhereby the $B$-spikes vanish when $\\epsilon_s^A / \\epsilon_s^B < 0.15$.\n  Eventually, performing an atomistic simulation of a (bio)-polymer {\\it\npolyglycine}, we demonstrate that the simulation results, derived from our\ncoarse-grained model, comply favorably with those from the all-atom simulation.",
        "positive": "Active Fluidification of Entangled Polymers by Loop Extrusion: Loop extrusion is one of the main processes shaping chromosome organisation\nacross the cell cycle, yet its role in regulating DNA entanglement and\nnucleoplasm viscoelasticty remains overlooked. We simulate entangled solutions\nof linear polymers under the action of generic Loop Extruding Factors (LEF)\nwith a model that fully accounts for topological constraints and LEF-DNA\nuncrossability. We discover that extrusion drives the formation of\nbottle-brush-like structures which significantly lower the entanglement and\neffective viscosity of the system through an active fluidification mechanism.\nInterestingly, this fluidification displays an optimum at one LEF every\n300-3000 basepairs. In marked contrast with entangled linear chains, the\nviscosity of extruded chains scales linearly with polymer length, yielding up\nto 1000-fold fluidification. Our results illuminate how loop extrusion\ncontributes to actively modulate genome entanglement and viscoelasticity in\nvivo."
    },
    {
        "anchor": "Confining deep eutectic solvents in nanopores: insight into\n  thermodynamics and chemical activity: We have established the detailed phase diagram of the prototypical deep\neutectic solvent ethaline (ethylene glycol / choline chloride 2:1) as a\nfunction of the hydration level, in the bulk state and confined in the\nnanochannels of mesostructured porous silica matrices MCM-41 and SBA-15, with\npore radii $R_P$ = 1.8 nm and 4.15 nm. For neat and moderately hydrated DESs,\nfreezing was avoided and glassforming solutions were formed in all cases. For\nmass fraction of water above a threshold value $W_g'\\approx30\\%$,\ncrystallization occurred and led to the formation of a maximally-freeze\nconcentrated DES solution. In this case, extremely deep melting depressions\nwere attained in the confined states, due to the combination of confinement and\ncryoscopic effects. These phenomena were analyzed quantitatively, based on an\nextended version of the classical Gibbs-Thomson and Raoult thermodynamic\napproaches. In this framework, the predicted values of the water chemical\nactivity in the confined systems were shown to systematically deviate from\nthose of the bulk counterparts. The origin of this striking observation is\ndiscussed with respect to thermodynamic anomalies of water in the 'no-man's\nland' and to the probable existence of specific nanostructures in DES solutions\nwhen manipulated in nanochannels or at interfaces with solids.",
        "positive": "Modeling liquid migration in active swollen gel spheres: Liquid migration in active soft solids is a very common phenomenon in Nature\nat different scales: from cells to leaves. It can be caused by mechanical as\nwell as chemical actions. The work focuses on the migration of liquid provoked\nby remodeling processes in an active impermeable gel sphere. Within this\ncontext, we present a consistent mathematical theory capable to gain a deep\nunderstanding of the phenomenon in both steady and transient conditions."
    },
    {
        "anchor": "The Hydrophobic Aggregation of Two Colloids: A Thermodynamic Model: Colloidal aggregation could be implemented in various fields ranging from\npurely colloidal thermodynamics to protein interactions, their stability, and\nmaybe folding. Indeed, colloidal aggregation is closely linked to the so-called\nhydrophobic effect for which a thermodynamic explanation is proposed. This\nexplanation is performed using Prigogine's out-of-equilibrium thermodynamics\nwhich is based on entropy production. It is shown that a likely destabilizing\nevent could induce a spontaneous and irreversible aggregation of two identical\nor different colloids as it causes the desorption of solvent molecules from\ncolloidal surfaces. This desorption is an entropy production factor through the\nchemical potentials minimization of, among others, initially adsorbed\nmolecules. This may be viewed as an increase of the so-called \"solvent entropy\"\nor \"translational entropy\".",
        "positive": "Splay-bend elastic inequalities shape tactoids, toroids, umbilics, and\n  conic section walls in paraelectric, twist-bend, and ferroelectric nematics: Elastic constants of splay K_11, twist K_22, and bend K_33 of nematic liquid\ncrystals are often assumed to be equal to each other in order to simplify the\ntheoretical description of complex director fields. Here we present examples of\nhow the disparity of K_11 and K_33 produces effects that cannot be described in\na one-constant approximation. In a lyotropic chromonic liquid crystal, nematic\ndroplets coexisting with the isotropic phase change their shape from a\nsimply-connected tactoid to a topologically distinct toroid as a result of\ntemperature or concentration variation. The transformation is caused by the\nincrease of the splay-to-bend ratio K_11/K_33. A phase transition from a\nconventional nematic to a twist-bend nematic implies that the ratio K_11/K_33\nchanges from very large to very small. As a result, the defects caused by an\nexternally applied electric field change the deformation mode of optic axis\nfrom bend to splay. In the paraelectric-ferroelectric nematic transition, one\nfinds an inverse situation: K_11/K_33 changes from small to large, which shapes\nthe domain walls in the spontaneous electric polarization field as conic\nsections. The polarization field tends to be solenoidal, or divergence-free, a\nbehavior complementary to irrotational curl-free director textures of a smectic\nA."
    },
    {
        "anchor": "Nonuniversality of the dispersion interaction: analytic benchmarks for\n  van der Waals energy functionals: We highlight the non-universality of the asymptotic behavior of dispersion\nforces, such that a sum of inverse sixth power contributions is often\ninadequate. We analytically evaluate the cross-correlation energy Ec between\ntwo pi-conjugated layers separated by a large distance D within the\nelectromagnetically non-retarded Random Phase Approximation, via a\ntight-binding model. For two perfect semimetallic graphene sheets at T=0K we\nfind Ec = C D^{-3}, in contrast to the \"insulating\" D^{-4} dependence predicted\nby currently accepted approximations. We also treat the case where one graphene\nlayer is replaced by a thin metal, a model relevant to the exfoliation of\ngraphite. Our general considerations also apply to nanotubes, nanowires and\nlayered metals.",
        "positive": "High-energy deformation of filaments with internal structure and\n  localized torque-induced melting of DNA: We develop a continuum elastic approach to examining the bending mechanics of\nsemiflexible filaments with a local internal degree of freedom that couples to\nthe bending modulus. We apply this model to study the nonlinear mechanics of a\ndouble stranded DNA oligomer (shorter than its thermal persistence length)\nwhose free ends are linked by a single standed DNA chain. This construct,\nstudied by Qu et al. [Europhys. Lett., $\\bf{94}$, 18003, 2011], displays\nnonlinear strain softening associated with the local melting of the double\nstranded DNA under applied torque and serves as a model system with which to\nstudy the nonlinear elasticity of DNA under large energy deformations. We show\nthat one can account quantitatively for the observed bending mechanics using an\naugmented worm-like chain model, the helix coil worm-like chain. We also\npredict that the highly bent and partially molten dsDNA should exhibit\nparticularly large end-to-end fluctuations associated with the fluctuation of\nthe length of the molten region, and propose appropriate experimental tests. We\nsuggest that the augmented worm-like chain model discussed here is a useful\nanalytic approach to the nonlinear mechanics of DNA or other biopolymer\nsystems."
    },
    {
        "anchor": "Questions of perfect lenses by left handed materials: We consider questions about the much discussed \"perfect lenses\" made by left\nhanded materials. The transmission and reflection from a slab of left handed\nmaterials are investigated and the coefficients are obtained by the standard\ntransfer matrix method. Possible limitations on such superlenses are explored.\nIt is shown that the quality of the lenses can be significantly affected by the\nabsorption that is necessarily present in the materials.",
        "positive": "Realization and Properties of Biochemical-Computing Biocatalytic XOR\n  Gate Based on Signal Change: We consider a realization of the XOR logic gate in a system involving two\ncompeting biocatalytic reactions, for which the logic-1 output is defined by\nthese two processes causing a change in the optically detected signal. A model\nis developed for describing such systems in an approach suitable for evaluation\nof the analog noise amplification properties of the gate and optimization of\nits functioning. The initial data are fitted for gate quality evaluation within\nthe developed model, and then modifications are proposed and experimentally\nrealized for improving the gate functioning."
    },
    {
        "anchor": "Design of Sequences with Good Folding Properties in Coarse-Grained\n  Protein Models: Background: Designing amino acid sequences that are stable in a given target\nstructure amounts to maximizing a conditional probability. A straightforward\napproach to accomplish this is a nested Monte Carlo where the conformation\nspace is explored over and over again for different fixed sequences, which\nrequires excessive computational demand. Several approximate attempts to remedy\nthis situation, based on energy minimization for fixed structure or high-$T$\nexpansions, have been proposed. These methods are fast but often not accurate\nsince folding occurs at low $T$.\n  Results: We develop a multisequence Monte Carlo procedure, where both\nsequence and conformation space are simultaneously probed with efficient\nprescriptions for pruning sequence space. The method is explored on\nhydrophobic/polar models. We first discuss short lattice chains, in order to\ncompare with exact data and with other methods. The method is then successfully\napplied to lattice chains with up to 50 monomers, and to off-lattice 20-mers.\n  Conclusions: The multisequence Monte Carlo method offers a new approach to\nsequence design in coarse-grained models. It is much more efficient than\nprevious Monte Carlo methods, and is, as it stands, applicable to a fairly wide\nrange of two-letter models.",
        "positive": "Studying Flow Close to an Interface by Total Internal Reflection\n  Fluorescence Cross Correlation Spectroscopy: Quantitative Data Analysis: Total Internal Reflection Fluorescence Cross Correlation Spectroscopy\n(TIR-FCCS) has recently (S. Yordanov et al., Optics Express 17, 21149 (2009))\nbeen established as an experimental method to probe hydrodynamic flows near\nsurfaces, on length scales of tens of nanometers. Its main advantage is that\nfluorescence only occurs for tracer particles close to the surface, thus\nresulting in high sensitivity. However, the measured correlation functions only\nprovide rather indirect information about the flow parameters of interest, such\nas the shear rate and the slip length. In the present paper, we show how to\ncombine detailed and fairly realistic theoretical modeling of the phenomena by\nBrownian Dynamics simulations with accurate measurements of the correlation\nfunctions, in order to establish a quantitative method to retrieve the flow\nproperties from the experiments. Firstly, Brownian Dynamics is used to sample\nhighly accurate correlation functions for a fixed set of model parameters.\nSecondly, these parameters are varied systematically by means of an\nimportance-sampling Monte Carlo procedure in order to fit the experiments. This\nprovides the optimum parameter values together with their statistical error\nbars. The approach is well suited for massively parallel computers, which\nallows us to do the data analysis within moderate computing times. The method\nis applied to flow near a hydrophilic surface, where the slip length is\nobserved to be smaller than 10nm, and, within the limitations of the\nexperiments and the model, indistinguishable from zero."
    },
    {
        "anchor": "Entangled polymer complex as Higgs phenomena: We derive an effective Maxwell-London equation for entangled polymer complex\nunder the topological constraint, borrowing the theoretical framework from the\ntopological field theory. We find that the transverse current flux of the test\npolymer chain, surrounded with entangled chains, decays exponentially from its\naverage position with finite penetration depth, which is analogous to the\nmagnetic-field decay in a superconductor (SC). Like as the mass acquirement of\nphotons in SC is the origin of the magnetic-field decay, the polymer earns\nuncrossible intersections along the chain due to the preserved linking number,\nwhich restricts the deviation of the transverse polymer current in the normal\ndirection. Interestingly, this picture is well incorporated with the most\nsuccessful phenomenological theory of the so called tube model, of which\nresearchers have long pursued its microscopic origin. The correspondence of our\nequation of motion to the tube model claims that the confining tube potential\nis a consequence of the topological constraint (linking number). The tube\nradius is attributed to the decay length, and increasing the retracting force\nat intersections or increasing the number of intersections (linking number),\nthe tube becomes narrow and tighter. It further shows that the probability of\nthe tube leakage decays exponentially with the decay length of tube radius.",
        "positive": "Radiation stability of biocompatibile magnetic fluid: The radiation stability of biocompatibile magnetic fluid used in nanomedicine\nafter electron irradiation was studied. Two types of the water-based magnetic\nfluids were prepared. The first one was based on the magnetite nanoparticles\nstabilized by one surfactant natrium oleate. The second one was biocompatibile\nmagnetic fluid stabilized with two surfactants, natrium oleate as a first\nsurfactant and Poly(ethylene glycol) (PEG) as a second surfactant. The\nmagnetization measurements showed that electron irradiation up to 1000Gy caused\n50% reduction of saturation magnetization in the case of the first sample with\nonly one surfactant while in the case of the second biocompatibile magnetic\nfluid, only 25% reduction of saturation magnetization was observed. In the\nfirst magnetic fluid the radiation caused the higher sedimentation of the\nmagnetic particles than in the second case, when magnetic particles are covered\nalso with PEG. The obtained results show that PEG behave as a protective\nelement."
    },
    {
        "anchor": "Characterization of PMMA--3-octanone binary by turbidity and light\n  scattering measurements: We measure the coexistence curve and the critical point properties of a\nbinary mixture composed by polymethylmethacrylate (PMMA) at $M_w = 55900$ g/mol\nwith 3- octanone. This binary mixture which has a demixing transition with an\nupper critical solution temperature $T_c$ has indeed interesting properties\nwhich may be useful for several application : a) its correlation length is\nlarger than that of a liquid-liquid binary mixture, b) it is less viscous than\na polymer blend; c) 3- octanone has an evaporation rate much smaller than other\nsolvents. The mixture is first characterized by turbidity, to get the demixing\ntemperature for different volumic fraction of PMMA. The coordinates of the\ncritical point are obtained: $\\phi_c = 12.8\\pm0.2$ % and $T_c = 306.5\\pm0.1$ K.\nThe correlation length $\\xi$ near the critical point is then measured in a\nsolution with a 12.8% volumic fraction of PMMA using static light scattering.\nUsing the fact that PMMA-octanone mixture has scaling exponents compatible with\nIsing 3D, we determine more precisely the critical temperature $T_c =\n306.58\\pm0.04$ K and we find that $\\xi \\simeq \\xi_0 [(T-T_c)/{T_c}]^{-0.63}$\nwith $\\xi_0 = 0.97\\pm 0.02$ nm. The discrepancy between this value and that\nextrapolated from other measurements based on turbidity is discussed.",
        "positive": "Low energy modes and Debye behaviour in a colloidal crystal: We study the vibrational spectrum and the low energy modes of a three\ndimensional colloidal crystal using confocal microscopy. This is done in a\ntwo-dimensional cut through a three-dimensional crystal. We find that the\nobserved density of states is incompatible with the standard Debye form in\neither two or three dimensions. These results are confirmed by numerical\nsimulations. We show that an effective theory for the projections of the modes\nonto the two-dimensional cut describes the experimental and simulation data in\na satisfactory way."
    },
    {
        "anchor": "Universal Ratios of Characteristic Lengths in Semidilute Polymer\n  Solutions: We use experimental and simulation data from the literature to infer five\ncharacteristic lengths, denoted $\\xi_s$, $\\xi_f$, $\\xi_\\Pi$, $\\xi_\\phi$, and\n$\\xi_D$ of a semidilute polymer solution. The first two of these are defined in\nterms of scattering from the solution, the third is defined in terms of osmotic\npressure, the fourth by the spatial monomer concentration profile, and the last\nby co-operative diffusion. In a given solution the ratios of any of these five\nlengths are expected to be universal constants. Knowing these constants thus\nallows one to use one measured property of a solution as a means of inferring\nothers. We calculate these ratios and estimate their uncertainties for\nsolutions in theta as well as good-solvent conditions. The analysis is\nstrengthened by use of scattering properties of isolated polymers inferred from\ncomputer simulations.",
        "positive": "Two dimensional MRT LB model for compressible and incompressible flows: In the paper we extend the Multiple-Relaxation-Time (MRT) Lattice Boltzmann\n(LB) model proposed in [Europhys. Lett. \\textbf{90}, 54003 (2010)] so that it\nis suitable also for incompressible flows. To decrease the artificial\noscillations, the convection term is discretized by the flux limiter scheme\nwith splitting technique. New model is validated by some well-known benchmark\ntests, including Riemann problem and Couette flow, and satisfying agreements\nare obtained between the simulation results and analytical ones. In order to\nshow the merit of LB model over traditional methods, the non-equilibrium\ncharacteristics of system are solved. The simulation results are consistent\nwith physical analysis."
    },
    {
        "anchor": "Connectedness percolation of hard convex polygonal rods and platelets: The properties of polymer composites with nanofiller particles change\ndrastically above a critical filler density known as the percolation threshold.\nReal nanofillers, such as graphene flakes and cellulose nanocrystals, are not\nidealized disks and rods but are often modeled as such. Here we investigate the\neffect of the shape of the particle cross section on the geometric percolation\nthreshold. Using connectedness percolation theory and the second-virial\napproximation, we analytically calculate the percolation threshold of hard\nconvex particles in terms of three single-particle measures. We apply this\nmethod to polygonal rods and platelets and find that the universal scaling of\nthe percolation threshold is lowered by decreasing the number of sides of the\nparticle cross section. This is caused by the increase of the surface area to\nvolume ratio with decreasing number of sides.",
        "positive": "Relaxing in foam: We investigate the mechanical response of an aqueous foam, and its relation\nto the microscopic rearrangement dynamics of the bubble-packing structure. At\nrest, even though the foam is coarsening, the rheology is demonstrated to be\nlinear. Under flow, shear-induced rearrangements compete with\ncoarsening-induced rearrangements. The macroscopic consequences are captured by\na novel rheological method in which a step-strain is superposed on an otherwise\nsteady flow."
    },
    {
        "anchor": "Effect of a potential softness on the solid-liquid transition in a\n  two-dimensional core-softened potential system: In the present paper, using a molecular dynamics simulation, we study a\nnature of melting of a two-dimensional ($2D$) system of classical particles\ninteracting through a purely repulsive isotropic core-softened potential which\nis used for the qualitative description of the anomalous behavior of water and\nsome other liquids. We show that the melting scenario drastically depends on\nthe potential softness and changes with increasing the width of the smooth\nrepulsive shoulder. While at small width of the repulsive shoulder the melting\ntransition exhibits what appears to be weakly first-order behavior, at larger\nvalues of the width a reentrant-melting transition occurs upon compression for\nnot too high pressures, and in the low density part of the $2D$ phase diagram\nmelting is a continuous two-stage transition, with an intermediate hexatic\nphase in accordance with the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY)\nscenario. On the other hand, at high density part of the phase diagram one\nfirst-order transition takes place. These results may be useful for the\nqualitative understanding the behavior of water confined between two\nhydrophobic plates.",
        "positive": "Targeted Assembly and Synchronization of Self-Spinning Microgears: Self-assembly is the autonomous organization of components into patterns or\nstructures: an essential ingredient of biology and a desired route to complex\norganization. At equilibrium, the structure is encoded through specific\ninteractions, at an unfavorable entropic cost for the system. An alternative\napproach, widely used by Nature, uses energy input to bypass the entropy\nbottleneck and develop features otherwise impossible at equilibrium.\nDissipative building blocks that inject energy locally were made available by\nrecent advance in colloidal science but have not been used to control\nself-assembly. Here we show the robust formation of self-powered rotors and\ndynamical superstructures from active particles and harness non-equilibrium\nphoretic phenomena to tailor interactions and direct self-assembly. We use a\nphotoactive component that consumes fuel, hematite, to devise phototactic\nmicroswimmers that form self-spinning microgears following spatiotemporal light\npatterns. The gears are coupled via their chemical clouds and constitute the\nelementary bricks of synchronized superstructures, which autonomously regulate\ntheir dynamics. The results are quantitatively rationalized on the basis of a\nstochastic description of diffusio-phoretic oscillators dynamically coupled by\nchemical gradients to form directional interactions. Our findings demonstrate\nthat non-equilibrium phenomena can be harnessed to shape interactions and\nprogram hierarchical constructions. It lays the groundwork for the\nself-assembly of dynamical architectures and synchronized micro-machinery."
    },
    {
        "anchor": "On bifurcation behavior of hard magnetic soft cantilevers: Hard magnetic materials belong to a novel class of soft active materials with\nthe capability of quick, large, and complex deformation via applying an\nexternal actuation. They have an extensive range of potential applications in\nsoft robots, biomedical devices, and stretchable electronics, etc. Recently,\ninvestigation on the experimental and theoretical nonlinear mechanics of hard\nmagnetic soft cantilevers has received notable considerations. In the available\nanalyses, the most attention was paid to the non-bifurcation-type nonlinear\nmechanics of the system, and bifurcation was considered for a specific case. In\nthe current study, the general trend of bifurcation-type nonlinear mechanics of\nhard magnetic soft cantilevers is introduced and the effective parameters on\nthe occurrence of bifurcation are identified. Additionally, new trajectories\ndue to the bifurcation and the corresponding workspace are presented.\nEventually, a comprehensive comparative study between the new trajectories and\nworkspace with those reported in the prior studies is carried out.",
        "positive": "Structure of the Lennard-Jones liquid estimated from a single simulation: Combining the recent Piskulich-Thompson approach [Z. A. Piskulich and W. H.\nThompson, {\\it J. Chem. Phys.} {\\bf 152}, 011102 (2020)] with isomorph theory,\nfrom a single simulation, the structure of a single-component Lennard-Jones\n(LJ) system is obtained at an arbitrary state point in almost the whole liquid\nregion of the temperature-density phase diagram. The LJ system exhibits two\ntemperature range where the van't Hoff's assumption that energetic and entropic\nforces are temperature independent is valid. A method to evaluate the structure\nat an arbitrary state point along an isochore from the knowledge of structures\nat two temperatures on the isochore is also discussed. We argue that, in\ngeneral, the structure of any hidden scale-invariant system obeying the van't\nHoff's assumption in the whole range of temperatures can be determined in the\nwhole liquid region of the phase diagram from only a single simulation."
    },
    {
        "anchor": "Introduction to colloidal dispersions in external fields: Progress in the research area of colloidal dispersions in external fields\nwithin the last years is reviewed. Colloidal dispersions play a pivotal role as\nmodel systems for phase transitions in classical statistical mechanics. In\nrecent years the leading role of colloids to realize model systems has become\nevident not only for equilibrium situations but also far away from equilibrium.\nBy using external fields (such as shear flow, electric, magnetic or\nlaseroptical fields as well as confinement), a colloidal suspension can be\nbrought into nonequilibrium in a controlled way. Various kinds of equilibrium\nand nonequilibrium phenomena explored by colloidal dispersions are described\nproviding also a guide and summary to this special issue. Particular emphasis\nis put on the comparison of real-space experiments, computer simulations and\nstatistical theories.",
        "positive": "Molecular Modelling Combined with Advanced Chemistry for the Rational\n  Design of Efficient Graphene Dispersing Agents: Pyrene-functional PMMAs were prepared via ATRP-controlled polymerization and\nclick reaction, as efficient dispersing agents for the exfoliation of\nfew-layered graphene sheets (GS) in easily processable low boiling point\nchloroform. In parallel, detailed atomistic simulations showed fine dispersion\nof the GS/polymer hybrids in good agreement with the experiment. Moreover, the\nmolecular dynamics simulations revealed interesting conformations (bridges,\nloops, dangling ends, free chains) of GS/polymer hybrids and allowed us to\nmonitor their time evolution both in solution and in the polymer nanocomposite\nwhere the solvent molecules were replaced with PMMA chains. Microscopic\ninformation about these structures is very important for optimizing mechanical\nperformance. It seems that the combination of atomistic simulation with\nadvanced chemistry constitutes a powerful tool for the design of effective\ngraphene dispersing agents that could be used for the production of\ngraphene-based nanocomposites with tailor-made mechanical properties."
    },
    {
        "anchor": "Reply to the Comment on \"Passage Times for Unbiased Polymer\n  Translocation through a Narrow Pore\": Theoretical derivation and numerical confirmation are provided for the\nscaling of pore-blockade times as $N^{2+\\nu}$ for unbiased translocation in two\nand three dimensions, with $N$ as the polymer length and $\\nu$ as the Flory\nexponent of the polymer. The polymer performs Rouse dynamics.",
        "positive": "The effect of AC electric field on the dynamics of a vesicle under shear\n  flow in the small deformation regime: Vesicles or biological cells under simultaneous shear and electric field can\nbe encountered in dielectrophoretic devices or devices used for continuous flow\nelectrofusion or electroporation. In this work, the dynamics of a vesicle\nsubjected to simultaneous shear and uniform AC electric field is investigated\nin the small deformation limit. The coupled equations for vesicle orientation\nand shape evolution are derived theoretically and the resulting nonlinear\nequations are handled numerically to generate relevant phase diagrams that\ndemonstrate the effect of electrical parameters on the different dynamical\nregimes such as tank-treading (TT), trembling (TR), and tumbling (TU). It is\nfound that while the electric Mason number (Mn) which represents the relative\nstrength of the electrical forces to the shear forces, promotes TT regime, the\nresponse itself is found to be sensitive to the applied frequency as well as\nthe conductivity ratio. While higher outer conductivity promotes orientation\nalong the flow axis, orientation along the electric field is favoured when the\ninner conductivity is higher. Similarly, a switch of orientation from the\ndirection of the electric field to the direction of flow is possible by a mere\nchange of frequency when the outer conductivity is higher. Interestingly, in\nsome cases, a coupling between electric field induced deformation and shear can\nresult in the system admitting an intermediate TU regime while attaining the TT\nregime at high Mn. The results could enable designing better dielectrophoretic\ndevices wherein the residence time, as well as the dynamical states of the\nvesicular suspension, can be controlled as per the application."
    },
    {
        "anchor": "Rheological Study of Transient Networks with Junctions of Limited\n  Multiplicity II. Sol/Gel Transition and Rheology: Viscoelastic and thermodynamic properties of transient gels formed by\ntelechelic polymers are studied on the basis of the transient network theory\nthat takes account of the correlation among polymer chains via network\njunctions. The global information of the gel is incorporated into the theory by\nintroducing the elastically effective chains according to the criterion by\nScanlan and Case. We also consider effects of superbridges whose backbone is\nformed by several chains connected in series with several breakable junctions\ninside. Near the critical concentration for the sol/gel transition,\nsuperbridges becomes infinitely long along the backbone, thereby leading to the\nshort relaxation time $\\tau$ of the network. It is shown that $\\tau$ is\nproportional to the concentration deviation $\\Delta$ near the gelation point.\nThe plateau modulus $G_{\\infty}$ increases as the cube of $\\Delta$ near the\ngelation point as a result of the mean-field treatment, and hence the\nzero-shear viscosity increases as $\\eta_0\\sim G_{\\infty}\\tau\\sim\\Delta^4$. The\ndynamic shear moduli are well described in terms of the Maxwell model, and it\nis shown that the present model can explain the concentration dependence of the\ndynamic moduli for aqueous solutions of telechelic poly(ethylene oxide).",
        "positive": "Numerical simulation of 2D steady granular flows in rotating drum: On\n  surface flows rheology: The rheology of 2D steady surface flow of cohesionless cylinders in a\nrotating drum is investigated through {\\em Non Smooth Contact Dynamics}\nsimulations. Profile of volume fraction, translational and angular velocity,\nrms velocity, strain rate and stress tensor were measured at the midpoint along\nthe length of the surface flowing layer where the flow is generally considered\nas steady and homogeneous. Analysis of these data and their inter-relations\nsuggest the local inertial number - defined as the ratio between local inertial\nforces and local confinement forces - to be the relevant dimensionless\nparameter to describe the transition from the quasi-static part of the packing\nto the flowing part at the surface of the heap. Variations of the components of\nthe stress tensor as well as the ones of rms velocity as a function of the\ninertial number are analysed within both the quasi-static and the flowing\nphases. Their implications are discussed."
    },
    {
        "anchor": "Statistical Theory of Initiation of Explosives by Impact: When a given weight dropped onto an explosive charge, explosion or not is\nprobabilistic for certain impact energy and the frequency of explosion is\nalways increase with increasing impact energy. Based on experimental results\nand recently theoretical work, we propose that the hot spot formation is\nattributed to the activated molecules decomposition and the number of molecules\ninitiation is proportional to the impact energy but not the dropped weight\nheating as the previous hot spot theory. A theoretical model based on two\nstates model has been put forward for this phenomena. It is shown that the\nactivated molecules to form a hot spot determine the probabilistic nature of\ninitiation by impact. It is shown a good agreement tested with Hexogen (RDX)\nexperimental impact data.",
        "positive": "Cylinder-flat contact mechanics during sliding: Using molecular dynamics (MD) we study the dependency of the contact\nmechanics on the sliding speed when an elastic block (cylinder) with a ${\\rm\ncos} (q_0 x)$ surface height profile is sliding in adhesive contact on a rigid\nflat substrate.The atoms on the block interact with the substrate atoms by\nLennard-Jones (LJ) potentials, and we consider both commensurate and(nearly)\nincommensurate contacts. For the incommensurate system the friction force\nfluctuates between positive and negative values, with an amplitude proportional\nto the sliding speed, but with the average close to zero. For the commensurate\nsystem the (time-averaged) friction force is much larger and nearly velocity\nindependent. For both type of systems the width of the contact region is\nvelocity independent even when, for the commensurate case, the frictional shear\nstress increases from zero (before sliding) to $\\approx 0.1 \\ {\\rm MPa}$ during\nsliding. This frictional shear stress, and the elastic modulus used, are\ntypical for Polydimethylsiloxan (PDMS) rubber sliding on a glass surface, and\nwe conclude that the reduction in the contact area observed in some experiments\nwhen increasing the tangential force must be due to effects not included in our\nmodel study, such as viscoelasticity or elastic nonlinearity"
    },
    {
        "anchor": "Thermal Denaturation of Fluctuating DNA Driven by Bending Entropy: A statistical model of homopolymer DNA, coupling internal base pair states\n(unbroken or broken) and external thermal chain fluctuations, is exactly solved\nusing transfer kernel techniques. The dependence on temperature and DNA length\nof the fraction of denaturation bubbles and their correlation length is\ndeduced. The thermal denaturation transition emerges naturally when the chain\nfluctuations are integrated out and is driven by the difference in bending\n(entropy dominated) free energy between broken and unbroken segments.\nConformational properties of DNA, such as persistence length and\nmean-square-radius, are also explicitly calculated, leading, e.g., to a\ncoherent explanation for the experimentally observed thermal viscosity\ntransition.",
        "positive": "Dynamic susceptibilities in dense soft athermal spheres under a\n  finite-rate shear: The mechanical responses of dense packings of soft athermal spheres under a\nfinite-rate shear are studied by means of molecular dynamics simulations. We\ninvestigate the volume fraction and shear rate dependence of the fluctuations\nin the shear stress and the interparticle contact number. In particular, we\nquantify them by defining the susceptibility as the ratio of the global to\nlocal fluctuations. The obtained susceptibilities form ridges on the volume\nfraction-shear rate plane, which are reminiscent of the Widom lines around the\ncritical point in an equilibrium phase transition."
    },
    {
        "anchor": "Mean-Field HP Model, Designability and Alpha-Helices in Protein\n  Structures: Analysis of the geometric properties of a mean-field HP model on a square\nlattice for protein structure shows that structures with large number of switch\nbacks between surface and core sites are chosen favorably by peptides as unique\nground states. Global comparison of model (binary) peptide sequences with\nconcatenated (binary) protein sequences listed in the Protein Data Bank and the\nDali Domain Dictionary indicates that the highest correlation occurs between\nmodel peptides choosing the favored structures and those portions of protein\nsequences containing alpha-helices.",
        "positive": "Structures and orientational transitions in thin films of tilted hexatic\n  smectics: We present detailed systematic studies of structural transformations in thin\nliquid crystal films with the smectic-C to hexatic phase transition. For the\nfirst time all possible structures reported in the literature are observed for\none material (5 O.6) at the variation of temperature and thickness. In unusual\nmodulated structures the equilibrium period of stripes is twice with respect to\nthe domain size. We interpret these patterns in the frame work of\nphenomenological Landau type theory, as equilibrium phenomena produced by a\nnatural geometric frustration in a system having spontaneous splay distortion."
    },
    {
        "anchor": "Effect of polydispersity on the relative stability of hard-sphere\n  crystals: By extending the nonequilibrium potential refinement algorithm and lattice\nswitch method to the semigrand ensemble, the semigrand potentials of the fcc\nand hcp structures of polydisperse hard-sphere crystals are calculated with the\nbias sampling scheme. The result shows that the fcc structure is more stable\nthan the hcp structure for polydisperse hard-sphere crystals below the terminal\npolydispersity.",
        "positive": "Thermodynamic State of the Interface during Acoustic Cavitation in Lipid\n  Suspensions: The thermodynamic state of lipid interfaces was observed during shock wave\ninduced cavitation in water with sub-microsecond resolution, using the emission\nspectra of hydration-sensitive fluorescent probes co-localized at the\ninterface. The experiments show that the cavitation threshold is lowest near a\nphase transition of the lipid interface. The cavitation collapse time and the\nmaximum state change during cavitation are found to be a function of both the\ndriving pressure and the initial state of the lipid interface. The experiments\nshow dehydration and crystallization of lipids during the expansion phase of\ncavitation, suggesting that the heat of vaporization is absorbed from within\nthe interface, which is adiabatically uncoupled from the free water. The study\nunderlines the critical role of the thermodynamic state of the interface in\ncavitation dynamics, which has mechanistic implications for ultrasound-mediated\ndrug delivery, acoustic nerve stimulation, ultrasound contrast agents, and the\nnucleation of ice during cavitation."
    },
    {
        "anchor": "Elastic Effects in Disordered Nematic Networks: Elastic effects in a model of disordered nematic elastomers are numerically\ninvestigated in two dimensions. Networks crosslinked in the isotropic phase\nexhibit unusual soft mechanical response against stretching. It arises from\ngradual alignment of orientationally correlated regions that are elongated\nalong the director. A sharp crossover to a macroscopically aligned state is\nobtained on further stretching. The effect of random internal stress is also\ndiscussed.",
        "positive": "The yield of Amorphous Solids Under Stress Control at Low Temperatures: The yield of amorphous solids like metallic glasses under external stress was\ndiscussed asserting that it is related to the glass transition by increasing\ntemperature, or that it can be understood using statistical theories of various\nsorts. Here we study the approach to stress-controlled yield and argue that\nneither assertions can be supported, at least at low temperatures. The yield of\namorphous solids at low temperatures is a highly structured phenomenon,\ncharacterized by a specific series of mechanical instabilities, and having no\nsimilarity at all to fluidization by increased temperature, real or fictive.\nThe series of instabilities followed by stress controlled yield at low but\nfinite temperature protocols can be predicted by analyzing athermal\nquasi-static strain controlled protocols, making the latter highly relevant for\nthe deep understanding of the mechanical properties of amorphous solids."
    },
    {
        "anchor": "Modelling unidirectional liquid spreading on slanted microposts: A lattice Boltzmann algorithm is used to simulate the slow spreading of drops\non a surface patterned with slanted micro-posts. Gibb's pinning of the\ninterface on the sides or top of the posts leads to unidirectional spreading\nover a wide range of contact angles and inclination angles of the posts.\nRegimes for spreading in no, one or two directions are identified, and shown to\nagree well with a two-dimensional theory proposed in Chu, Xiao and Wang (Nature\nMaterials, 9, 413). A more detailed numerical analysis of the contact line\nshapes allows us to understand deviations from the two dimensional model, and\nto identify the shapes of the pinned interfaces.",
        "positive": "Anomalous melting behavior under extreme conditions: hard matter turning\n  \"soft\": We show that a system of particles interacting through the exp-6 pair\npotential, commonly used to describe effective interatomic forces under high\ncompression, exhibits anomalous melting features such as reentrant melting and\na rich solid polymorphism, including a stable BC8 crystal. We relate this\nbehavior to the crossover, with increasing pressure, between two different\nregimes of local order that are associated with the two repulsive length scales\nof the potential. Our results provide a unifying picture for the high-pressure\nmelting anomalies observed in many elements and point out that, under extreme\nconditions, atomic systems may reveal surprising similarities with soft matter."
    },
    {
        "anchor": "Steady state rheological behaviour of multi-component magnetic\n  suspensions: In this paper we study the rheological behaviour (in the absence of magnetic\nfield and upon its application) of multi-component magnetic suspensions that\nconsist of a mixture of magnetic (iron) and non-magnetic (PMMA) particles\ndispersed in a liquid carrier. These suspensions exhibit considerably higher\nviscosity and yield stress in the absence of magnetic field than\nsingle-component suspensions of the same solid fraction, as a consequence of\nthe adsorption of the iron particles on the PMMA ones. The adsorbed layer of\niron particles on the PMMA ones is observed through optical microscopy of\ndilute samples and confirmed by attenuated total reflectance. Microscopic\nobservations also show that the resulting non-magnetic-core-magnetic-shell\ncomposites move upon magnetic field application and aggregate into particle\nstructures aligned with the applied field. These structures, which consist of\nboth types of particles, give rise to high values of the static and dynamic\nyield stresses upon field application. Actually, both quantities are much\nhigher than those of a suspension with the same volume fraction of magnetic\nparticles, and increase when the amount of non-magnetic ones increases. These\ntrends are adequately predicted by a theoretical model that considers that the\nmain contribution to the yield stress is the change of the suspension magnetic\npermeability when particle chains are deformed by the shear.",
        "positive": "Desiccation of a clay film: Cracking versus peeling: Cracking and peeling of a layer of clay on desiccation has been simulated\nusing a spring model. A vertical section through the layer with finite\nthickness is represented by a rectangular array of nodes connected by linear\nsprings on a square lattice. The effect of reduction of the natural length of\nthe springs, which mimics the drying is studied. Varying the strength of\nadhesion between sample and substrate and the rate of penetration of the drying\nfront produces an interesting phase diagram, showing cross-over from peeling to\ncracking behavior. Changes in the number and width of cracks on varying the\nlayer thickness is observed to reproduce experimental reports."
    },
    {
        "anchor": "Multiscale modeling and simulation for polymer melt flows between\n  parallel plates: The flow behaviors of polymer melt composed of short chains with ten beads\nbetween parallel plates are simulated by using a hybrid method of molecular\ndynamics and computational fluid dynamics. Three problems are solved: creep\nmotion under a constant shear stress and its recovery motion after removing the\nstress, pressure-driven flows, and the flows in rapidly oscillating plates. In\nthe creep/recovery problem, the delayed elastic deformation in the creep motion\nand evident elastic behavior in the recovery motion are demonstrated. The\nvelocity profiles of the melt in pressure-driven flows are quite different from\nthose of Newtonian fluid due to shear thinning. Velocity gradients of the melt\nbecome steeper near the plates and flatter at the middle between the plates as\nthe pressure gradient increases and the temperature decreases. In the rapidly\noscillating plates, the viscous boundary layer of the melt is much thinner than\nthat of Newtonian fluid due to the shear thinning of the melt. Three different\nrheological regimes, i.e., the viscous fluid, visco-elastic liquid, and\nvisco-elastic solid regimes, form over the oscillating plate according to the\nlocal Deborah numbers. The melt behaves as a viscous fluid in a region for\n$\\omega\\tau^R\\lesssim 1$, and the crossover between the liquid-like and\nsolid-like regime takes place around $\\omega\\tau^\\alpha\\simeq 1$ (where\n$\\omega$ is the angular frequency of the plate and $\\tau^R$ and $\\tau^\\alpha$\nare Rouse and $\\alpha$ relaxation time, respectively).",
        "positive": "Sedimentation of colloidal plate-sphere mixtures and inference of\n  particle characteristics from stacking sequences: We investigate theoretically the effect of gravity on a plate-sphere\ncolloidal mixture by means of an Onsager-like density functional to describe\nthe bulk, and sedimentation path theory to incorporate gravity. We calculate\nthe stacking diagram of the mixture for two sets of buoyant masses and\ndifferent values of the sample height. Several stacking sequences appear due to\nthe intricate interplay between gravity, the sample height, and bulk phase\nseparation. These include the experimentally observed floating nematic\nsequence, which consists of a nematic layer sandwiched between two isotropic\nlayers. The values of the thicknesses of the layers in a complex stacking\nsequence can be used to obtain microscopic information of the mixture. Using\nthe thicknesses of the layers in the floating nematic sequence we are able to\ninfer the values of the buoyant masses from the colloidal concentrations and\nvice versa. We also predict new phenomena that can be experimentally tested,\nsuch as a nontrivial evolution of the stacking sequence by increasing the\nsample height in which new layers appear either at the top or at the bottom of\nthe sample."
    },
    {
        "anchor": "Relaxation dynamics of two-component fluid bilayer membranes: We theoretically investigate the relaxation dynamics of a nearly-flat binary\nlipid bilayer membrane by taking into account the membrane tension,\nhydrodynamics of the surrounding fluid, inter-monolayer friction and mutual\ndiffusion in each monolayer. We find that two relaxation modes associated with\nthe mutual diffusion appear in addition to the three previously discussed\nrelaxation modes reflecting the bending and compression of the membrane.\nBecause of the symmetry, only one of the two diffusive mode is coupled to the\nbending mode. The two diffusive modes are much slower than the bending and\ncompression modes in the entire realistic wave number range. This means that\nthe long time relaxation behavior is dominated by the mutual diffusion in\nbinary membranes. The two diffusive modes become even slower in the vicinity of\nthe unstable region towards phase separation, while the other modes are almost\nunchanged. In short time scales, on the other hand, the lipid composition\nheterogeneity induces in-plane compression and bending of the bilayer.",
        "positive": "Macroscopic quantum self-trapping and atomic tunneling in two-species\n  Bose-Einstein condensates: We present a new theoretical treatment of macroscopic quantum self-trapping\n(MQST) and quantum coherent atomic tunneling in a zero-temperature two-species\nBose-Einstein condensate system in the presence of the nonlinear\nself-interaction of each species, the interspecies nonlinear interaction, and\nthe Josephson-like tunneling interaction. It is shown that the nonlinear\ninteractions can dramatically affect the MQST and the atomic tunneling, and\nlead to the collapses and revivals (CR) of population imbalance between the two\ncondensates. The competing effects between the self-interaction of each species\nand the interspecies interaction can lead to the quenching of the MQST and the\nsuppression of the CR and the Shapiro-like steps of the atomic tunneling\ncurrent. It is revealed that the interatomic nonlinear interactions can induce\nthe coherent atomic tunneling between two condensates even though there does\nnot exist the interspecies Josephson-like tunneling coupling."
    },
    {
        "anchor": "Local Ordering Of Polymer-Tethered Nanospheres And Nanorods And The\n  Stabilization Of The Double Gyroid Phase: We present results of Brownian dynamics simulations of tethered nanospheres\nand tethered nanorods. Immiscibility between tether and nanoparticle\nfacilitates microphase separation into the bicontinuous, double gyroid\nstructure (first reported by Iacovella et al. [Phys. Rev. E 75 (2007)] and\nHorsch et al. [J. Chem. Phys. 125 (2006)] respectively). We demonstrate the\nability of these nanoparticles to adopt distinct, minimal energy local\npackings, in which nanospheres form icosahedral-like clusters and nanorods form\nsplayed hexagonal bundles. These local structures reduce packing frustration\nwithin the nodes of the double gyroid. We argue that the ability to locally\norder into stable structures is key to the formation of the double gyroid phase\nin these systems.",
        "positive": "Ordering Phenomena on Growing Films: In many growth processes particles are highly mobile in an active layer at\nthe surface, but are relatively immobile once incorporated in the bulk. We\nstudy models in which atoms are allowed to interact, equilibrate, and order on\nthe surface, but are frozen in the bulk. Order parameter correlations in the\nresulting bulk material are highly anisotropic, reflecting its growth history.\nIn a flat (layer by layer) growth mode, correlations perpendicular to the\ngrowth direction are similar to a two dimensional system in equilibrium, while\nparallel correlations reflect the dynamics of such a system. When the growing\nfilm is rough, various couplings between height and order parameter\nfluctuations are possible. Such couplings modify the dynamic scaling properties\nof surface roughness, and may also change the critical behavior of the order\nparameter. Even the deterministic growth of the surface profile can result in\ninteresting textures for the order parameter."
    },
    {
        "anchor": "Activity-Enhanced Self-Assembly of a Colloidal Kagome Lattice: Here, we describe a method for the enhanced self-assembly of triblock Janus\ncolloids targeted to form a kagome lattice. Using computer simulations, we\ndemonstrate that the formation of this elusive structure can be significantly\nimproved by self-propelling or activating the colloids along the axis\nconnecting their hydrophobic hemispheres. The process by which metastable\naggregates are destabilized and transformed into the favored kagome lattice is\nquite general, and we argue this active approach provides a systematic pathway\nto improving the self-assembly of a large number of colloidal structures.",
        "positive": "Disorder effects on the static scattering function of star branched\n  polymers: We present an analysis of the impact of structural disorder on the static\nscattering function of f-armed star branched polymers in d dimensions. To this\nend, we consider the model of a star polymer immersed in a good solvent in the\npresence of structural defects, correlated at large distances r according to a\npower law \\sim r^{-a}. In particular, we are interested in the ratio g(f) of\nthe radii of gyration of star and linear polymers of the same molecular weight,\nwhich is a universal experimentally measurable quantity. We apply a direct\npolymer renormalization approach and evaluate the results within the double\n\\varepsilon=4-d, \\delta=4-a-expansion. We find an increase of g(f) with an\nincreasing \\delta. Therefore, an increase of disorder correlations leads to an\nincrease of the size measure of a star relative to linear polymers of the same\nmolecular weight."
    },
    {
        "anchor": "Column size effects of DER fluids: The static yield stress of dielectric electrorheological(DER) fluids of\ninfinite column state and chain state are calculated from the first principle\nmethod. The results indicate that the column surface contributions to ER\neffects is very small and both states will give correct results to the real DER\nfluids.",
        "positive": "Microscopic theory for electrocaloric effects in planar double layer\n  systems: We present a field theory approach to study changes in local temperature due\nto an applied electric field (the electrocaloric effect) in electrolyte\nsolutions. Steric effects and a field-dependent dielectric function are found\nto be of paramount importance for accurate estimations of the electrocaloric\neffect. Interestingly, electrolyte solutions are found to exhibit negative\nelectrocaloric effects. Overall, our results point toward using fluids near\nroom temperature with low heat capacity and high salt concentration for\nenhanced electrocalorics."
    },
    {
        "anchor": "Universal Poisson statistics of a passive tracer diffusing in dilute\n  active suspensions: The statistics of a passive tracer immersed in a suspension of active\nself-propelled particles (swimmers) is derived from first principles by\nconsidering a perturbative expansion of the tracer interaction with the\nmicroscopic swimmer field. To first order in the swimmer density, the tracer\nstatistics is exactly represented as a spatial Poisson process combined with\nindependent swimmer-tracer scattering events, rigorously reducing the\nmulti-particle dynamics to two-body interactions. The Poisson representation is\nvalid in any dimensions and for arbitrary interaction forces and swimmer\ndynamics. It provides in particular an analytical derivation of the coloured\nPoisson process introduced in [K. Kanazawa et al.; Nature 579, 364 (2020)]\nhighlighting that such a non-Markovian process can be obtained from Markovian\ndynamics by a variable transformation.",
        "positive": "Active microrheology of a bulk metallic glass: The glass transition remains unclarified in condensed matter physics.\nInvestigating the mechanical properties of glass is challenging because any\nglobal deformation that may result in shear rejuvenation requires an\nastronomical relaxation time. Moreover, it is well known that a glass is\nheterogeneous and a global perturbation cannot explore local\nmechanical/transport properties. However, an investigation based on a local\nprobe, i.e. microrheology, may overcome these problems. Here, we establish\nactive microrheology of a bulk metallic glass: a probe particle driven into\nhost medium glass. This is a technique amenable for experimental\ninvestigations. We show that upon cooling the microscopic friction exhibits a\nsecond-order phase transition; this sheds light on the origin of friction in\nheterogeneous materials. Further, we provide distinct evidence to demonstrate\nthat a strong relationship exists between the microscopic dynamics of the probe\nparticle and the macroscopic properties of the host medium glass. These\nfindings establish active microrheology as a promising technique for\ninvestigating the local properties of bulk metallic glass."
    },
    {
        "anchor": "Phase Separation in a Simple Model with Dynamical Asymmetry: We perform computer simulations of a Cahn-Hilliard model of phase separation\nwhich has dynamical asymmetry between the two coexisting phases. The dynamical\nasymmetry is incorporated by considering a mobility function which is order\nparameter dependent. Simulations of this model reveal morphological features\nsimilar to those observed in viscoelastic phase separation. In the early\nstages, the minority phase domains form a percolating structure which shrinks\nwith time eventually leading to the formation of disconnected domains. The\ndomains grow as L(t) ~ t^{1/3} in the very late stages. Although dynamical\nscaling is violated in the area shrinking regime, it is restored at late times.\nHowever, the form of the scaling function is found to depend on the extent of\ndynamical asymmetry.",
        "positive": "Pulmonary surfactant inhibition of nanoparticle uptake by alveolar\n  epithelial cells: Pulmonary surfactant forms a sub-micrometer thick fluid layer that covers the\nsurface of alveolar lumen and inhaled nanoparticles therefore come in to\ncontact with surfactant prior to any interaction with epithelial cells. We\ninvestigate the role of the surfactant as a protective physical barrier by\nmodeling the interactions using silica-Curosurf-alveolar epithelial cell system\nin vitro. Electron microscopy displays that the vesicles are preserved in the\npresence of nanoparticles while nanoparticle-lipid interaction leads to the\nformation of mixed aggregates. Fluorescence microscopy reveals that the\nsurfactant decreases the uptake of nanoparticles by up to two orders of\nmagnitude in two models of alveolar epithelial cells, A549 and NCI-H441,\nirrespective of immersed culture on glass or air-liquid interface culture on\ntranswell. Confocal microscopy corroborates the results by showing\nnanoparticle-lipid colocalization interacting with the cells. Our work thus\nsupports the idea that pulmonary surfactant plays a protective role against\ninhaled nanoparticles. The effect of surfactant should therefore be considered\nin predictive assessment of nanoparticle toxicity or drug nanocarrier uptake.\nModels based on the one presented in this work may be used for preclinical\ntests with engineered nanoparticles."
    },
    {
        "anchor": "Elastic modulus and yield strength of semicrystalline polymers with bond\n  disorder are higher than in atomic crystals: We perform thorough molecular-dynamics simulations to compare elasticity and\nyielding of atomic crystals and model semicrystalline polymers, the latter\ncharacterized by very similar positional ordering with respect to atomic\ncrystals and considerable bond disorder. We find that the elastic modulus, the\nshear yield strength and the critical yield strain of semicrystalline polymers\nare higher than (modulus and yield strength), or comparable to (critical\nstrain), the corresponding ones of atomic crystals. The findings suggest that\nthe bond disorder suppresses dislocation-mediated plasticity in polymeric\nsolids with positional order.",
        "positive": "Nanofluidic logic with mechano-ionic memristive switches: While most neuromorphic systems are based on nanoscale electronic devices,\nnature relies on ions for energy-efficient information processing. Therefore,\nfinding memristive nanofluidic devices is a milestone toward realizing\nelectrolytic computers mimicking the brain down to its basic principles of\noperation. Here, we present a nanofluidic device designed for circuit scale\nin-memory processing that combines single-digit nanometric confinement and\nlarge entrance asymmetry. Our fabrication process is scalable while the device\noperates at the second timescale with a conductance ratio in the range 10-60.\nIn-operando optical microscopy unveils the origin of memory, arising from the\nreversible formation of liquid blisters modulating the device conductance. The\ncombination of features of these mechano-ionic memristive switches permits\nassembling logic circuits composed of two interactive devices and an ohmic\nresistor. These results open the way to design multi-component ionic machinery,\nsuch as nanofluidic neural networks, and implementing brain-inspired ionic\ncomputations."
    },
    {
        "anchor": "Observation of Chaotic Dynamics in Dilute Sheared Aqueous Solutions of\n  CTAT: The nonlinear flow behaviour of a viscoelastic gel formed due to entangled,\ncylindrical micelles in aqueous solutions of the surfactant CTAT has been\nstudied. On subjecting the system to a step shear rate lying above a certain\nvalue, the shear and normal stresses show interesting time dependent behaviour.\nThe analysis of the measured time series shows the existence of a finite\ncorrelation dimension and a positive Lyapunov exponent, unambiguously implying\nthat the dynamics can be described by that of a dynamical system with a strange\nattractor whose dimension increases with the increase in shear rate.",
        "positive": "Parallel Excluded Volume Tempering for Polymer Melts: We have developed a technique to accelerate the acquisition of effectively\nuncorrelated configurations for off-lattice models of dense polymer melts which\nmakes use of both parallel tempering and large scale Monte Carlo moves. The\nmethod is based upon simulating a set of systems in parallel, each of which has\na slightly different repulsive core potential, such that a thermodynamic path\nfrom full excluded volume to an ideal gas of random walks is generated. While\neach system is run with standard stochastic dynamics, resulting in an NVT\nensemble, we implement the parallel tempering through stochastic swaps between\nthe configurations of adjacent potentials, and the large scale Monte Carlo\nmoves through attempted pivot and translation moves which reach a realistic\nacceptance probability as the limit of the ideal gas of random walks is\napproached. Compared to pure stochastic dynamics, this results in an increased\nefficiency even for a system of chains as short as $N = 60$ monomers, however\nat this chain length the large scale Monte Carlo moves were ineffective. For\neven longer chains the speedup becomes substantial, as observed from\npreliminary data for $N = 200$."
    },
    {
        "anchor": "Emergent hyperuniformity in periodically-driven emulsions: We report the emergence of large-scale hyperuniformity in microfluidic\nemulsions. Upon periodic driving confined emulsions undergo a first-order\ntransition from a reversible to an irreversible dynamics. We evidence that this\ndynamical transition is accompanied by structural changes at all scales\nyielding macroscopic yet finite hyperuniform structures. Numerical simulations\nare performed to single out the very ingredients responsible for the\nsuppression of density fluctuations. We show that as opposed to equilibrium\nsystems the long-range nature of the hydrodynamic interactions are not required\nfor the formation of hyperuniform patterns, thereby suggesting a robust\nrelation between reversibility and hyperuniformity which should hold in a broad\nclass of periodically driven materials.",
        "positive": "Softly Constrained Films: The shape of materials is often subject to a number of geometric constraints\nthat limit the size of the system or fix the structure of its boundary. In soft\nand biological materials, however, these constraints are not always hard, but\nare due to other physical mechanisms that affect the overall force balance. A\ncapillary film spanning a flexible piece of wire or a cell anchored to a\ncompliant substrate by mean of adhesive contacts are examples of these softly\nconstrained systems in the macroscopic and microscopic world. In this article I\nreview some of the important mathematical and physical developments that\ncontributed to our understanding of shape formation in softly constrained films\nand their recent application to the mechanics of adherent cells."
    },
    {
        "anchor": "Bedforms in a turbulent stream.Part 1: Turbulent flow over topography: In the context of subaqueous ripple and dune formation, we present here a\nReynolds averaged calculation of the turbulent flow over a topography. We\nperform a weakly non-linear expansion of the velocity field, sufficiently\naccurate to recover the separation of streamlines and the formation of a\nrecirculation bubble above some aspect ratio. The basal stresses are\ninvestigated in details; in particular, we show that the phase shift of the\nshear stress with respect to the topography, responsible for the formation of\nbedforms, appears in an inner boundary layer where shear stress and pressure\ngradients balance. We study the sensitivity of the calculation with respect to\n(i) the choice of the turbulence closure, (ii) the motion of the bottom (growth\nor propagation), (iii) the physics at work in the surface layer, responsible\nfor the hydrodynamic roughness of the bottom, (iv) the aspect ratio of the\nbedform and (v) the effect of the free surface, which can be interpreted in\nterms of standing gravity waves excited by topography. The most important\neffects are those of points (iii) to (v). We show that the dynamical mechanisms\ncontrolling the hydrodynamical roughness (mixing due to roughness elements,\nviscosity, sediment transport, etc) have an influence on the basal shear stress\nwhen the thickness of the surface layer is comparable to that of the inner\nlayer. We evidence that non-linear effects tend to oppose linear ones and are\nof the same order for bedform aspect ratios of the order of 1/10. We show that\nthe influence of the free surface on the basal shear stress is dominant when\nthe wavelength is large compared to the flow depth, so that the inner layer\nextends throughout the flow and in the resonant conditions, and when the\ndownstream material velocity balances the upstream wave propagation.",
        "positive": "The surprising dynamics of a chain on a pulley: Lift-off and snapping: The motion of weights attached to a chain or string moving on a frictionless\npulley is a classic problem of introductory physics used to understand the\nrelationship between force and acceleration. Here, we consider the dynamics of\nthe chain when one of the weights is removed and, thus, one end is pulled with\nconstant acceleration. This simple change has dramatic consequences for the\nensuing motion: at a finite time, the chain `lifts off' from the pulley and the\nfree end subsequently accelerates faster than the end that is pulled.\nEventually, the chain undergoes a dramatic reversal of curvature reminiscent of\nthe crack, or snap, of a whip. We combine experiments, numerical simulations,\nand theoretical arguments to explain key aspects of this dynamical problem."
    },
    {
        "anchor": "Introduction to Molecular-Scale Understanding of Surface Tension: In this article, microscopic understanding of the surface tension are\nprovided, which needs basic knowledge of thermodynamics, statistical mechanics\nas well as continuum mechanics. By introducing the intermolecular interaction\npotential and temperature definition, and by showing conceptual pictures\nincluding some results obtained by molecular dynamics simulations, the author\nhopes that the target readers of undergraduate level students can find\nfascinating aspects of surface tension as the boundary of macroscopic and\nmicroscopic physics.",
        "positive": "Space-resolved dynamic light scattering within a millimetric drop: from\n  Brownian diffusion to the swelling of hydrogel beads: We present a novel dynamic light scattering setup to probe, with time and\nspace resolution, the microscopic dynamics of soft matter systems confined\nwithin millimeter-sized spherical drops. By using an ad-hoc optical layout, we\ntackle the challenges raised by refraction effects due to the unconventional\nshape of the samples. We first validate the setup by investigating the dynamics\nof a suspension of Brownian particles. The dynamics measured at different\npositions in the drop, and hence different scattering angles, are found to be\nin excellent agreement with those obtained for the same sample in a\nconventional light scattering setup. We then demonstrate the setup capabilities\nby investigating a bead made of a polymer hydrogel undergoing swelling. The gel\nmicroscopic dynamics exhibit a space dependence that strongly varies with time\nelapsed since the beginning of swelling. Initially, the dynamics in the\nperiphery of the bead are much faster than in the core, indicative of\nnon-uniform swelling. As the swelling proceeds, the dynamics slow down and\nbecome more spatially homogeneous. By comparing the experimental results to\nnumerical and analytical calculations for the dynamics of a homogeneous, purely\nelastic sphere undergoing swelling, we establish that the mean square\ndisplacement of the gel strands deviates from the affine motion inferred from\nthe macroscopic deformation, evolving from fast diffusive-like dynamics at the\nonset of swelling to slower, yet supradiffusive, rearrangements at later\nstages."
    },
    {
        "anchor": "Topological mechanics of origami and kirigami: Origami and kirigami have emerged as potential tools for the design of\nmechanical metamaterials whose properties such as curvature, Poisson ratio, and\nexistence of metastable states can be tuned using purely geometric criteria. A\nmajor obstacle to exploiting this property is the scarcity of tools to identify\nand program the flexibility of fold patterns. We exploit a recent connection\nbetween spring networks and quantum topological states to design origami with\nlocalized folding motions at boundaries and study them both experimentally and\ntheoretically. These folding motions exist due to an underlying topological\ninvariant rather than a local imbalance between constraints and degrees of\nfreedom. We give a simple example of a quasi-1D folding pattern that realizes\nsuch topological states. We also demonstrate how to generalize these\ntopological design principles to two dimensions. A striking consequence is that\na domain wall between two topologically distinct, mechanically rigid structures\nis deformable even when constraints locally match the degrees of freedom.",
        "positive": "Passive particle in an active bath: How can we tell it is out of\n  equilibrium?: We study a passive probe immersed in a fluid of active particles. Despite the\nsystem's non-equilibrium nature, the trajectory of the probe does not exhibit\nnon-equilibrium signatures: its velocity distribution remains Gaussian, the\nsecond fluctuation dissipation theorem is not fundamentally violated, and the\nmotion does not indicate breaking of time reversal symmetry. To tell that the\nprobe is out of equilibrium requires examination of its behavior in tandem with\nthat of the active fluid: the kinetic temperature of the probe does not\nequilibrate to that of the surrounding active particles. As a strategy to\ndiagnose non-equilibrium from probe trajectories alone, we propose to examine\ntheir response to a small perturbation which reveals a non-equilibrium\nsignature through a violation of the first fluctuation dissipation theorem."
    },
    {
        "anchor": "Kinetic control of the coverage of oil droplets by DNA-functionalised\n  colloids: We report a study of reversible adsorption of DNA-coated colloids on\ncomplementary functionalized oil droplets. We show that it is possible to\ncontrol the surface coverage of oil droplets by colloidal particles, by\nexploiting the fact that during slow adsorption, compositional arrest takes\nplace well before structural arrest occurs. As a consequence, we can prepare\ncolloid-coated oil droplets with a `frozen' degree of loading, but with fully\nergodic colloidal dynamics on the droplets. We illustrate the equilibrium\nnature of the adsorbed colloidal phase by exploring the quasi two-dimensional\n(2d) phase behaviour of the adsorbed colloids under the influence of depletion\ninteractions. We present simulations of a simple model that illustrates the\nnature of the compositional arrest and the structural ergodicity.",
        "positive": "Torsional Instabilities in the Delamination of Soft Adhesives: Soft adhesive contacts are ubiquitous in nature and are increasingly used in\nsynthetic systems, such as flexible electronics and soft robots, due to their\nadvantages over traditional joining techniques. While methods to study the\nfailure of adhesives typically apply tensile loads to the adhesive joint, less\nis known about the performance of soft adhesives under shear and torsion, which\nmay become important in engineering applications. A major challenge that has\nhindered the characterization of shear/torsion-induced delamination is imposed\nby the fact that, even after delamination, contact with the substrate is\nmaintained, thus allowing for frictional sliding and re-adhesion. In this work,\nwe address this gap by studying the controlled delamination of soft cylinders\nunder combined compression and torsion. Our experimental observations expose\nthe nucleation of delamination at an imperfection and its propagation along the\ncircumference of the cylinder. The observed sequence of `stick-slip' events and\nthe sensitivity of the delamination process to material parameters are\nexplained by a theoretical model that captures axisymmetric delamination\npatterns, along with the subsequent frictional sliding and re-adhesion. By\nopening up an avenue for improved characterization of adhesive failure, our\nexperimental approach and theoretical framework can guide the design of\nadhesives in future applications."
    },
    {
        "anchor": "Role of electrostatic forces in cluster formation in a dry ionomer: This simulation study investigates the dependence of the structure of dry\nNafion$^{\\tiny\\textregistered}$-like ionomers on the electrostatic interactions\nbetween the components of the molecules. In order to speed equilibration, a\nprocedure was adopted which involved detaching the side chains from the\nbackbone and cutting the backbone into segments, and then reassembling the\nmacromolecule by means of a strong imposed attractive force between the cut\nends of the backbone, and between the non-ionic ends of the side chains and the\nmidpoints of the backbone segments. Parameters varied in this study include the\ndielectric constant, the free volume, side-chain length, and strength of\nhead-group interactions. A series of coarse-grained mesoscale simulations shows\nthe morphlogy to depend sensitively on the ratio of the strength of the\ndipole-dipole interactions between the side-chain acidic end groups to the\nstrength of the other electrostatic components of the Hamiltonian. Examples of\nthe two differing morphologies proposed by Gierke and by Gebel emerge from our\nsimulations.",
        "positive": "Composition Heterogeneity Induced Crystallization in Double Crystalline\n  Binary Polymer Blends: Polymer blends offer an exciting material for various potential applications\ndue to their tunable properties by varying constituting components and their\nrelative composition. Our simulation results unravel an intrinsic relationship\nbetween the phase behavior and crystallization characteristics with the\nrelative composition of A- and B-polymer in the system. We report simulation\nresults for non-isothermal and isothermal crystallization with weak and strong\nsegregation strength to elucidate the composition dependent crystallization\nbehavior. With increasing composition of low melting B-polymer, macrophase\nseparation and crystallization temperature changes non-monotonically, which is\nattributed to the change in diffusivity of both the polymers with increasing\ncomposition of B-polymer. In weak segregation strength, however, at high enough\ncomposition of B-polymer, A-polymer yields relatively thicker crystals, which\nis attributed to the dilution effect exhibited by B-polymer. When B-polymer\ncomposition is high enough, it acts like a solvent while A-polymer\ncrystallizes. Under this situation, A-polymer segments become more mobile and\nless facile to crystallize. As a result, A-polymer crystallizes at a relative\nlow temperature with the formation of thicker crystals. At strong segregation\nstrength, dilution effect is accompanied with the strong A-B repulsive\ninteraction, which is reflected in non-monotonic trend of mean square radius of\ngyration with increasing composition of B-polymer. Isothermal crystallization\nreveals a strong relationship between composition and crystallization behavior.\nTwo-step (viz., sequential crystallization) yields better crystals than\none-step (viz., coincident crystallization) for both the polymers."
    },
    {
        "anchor": "A multi-blob representation of semi-dilute polymer solutions: A coarse-grained multi-blob description of polymer solutions is presented,\nbased on soft, transferable effective interactions between bonded and\nnon-bonded blobs. The number of blobs is chosen such that the blob density does\nnot exceed their overlap threshold, allowing polymer concentrations to be\nexplored deep into the semi-dilute regime. This quantitative multi-blob\ndescription is shown to preserve known scaling laws of polymer solutions and\nprovides accurate estimates of amplitudes, while leading to orders of magnitude\nincrease of simulation efficiency and allowing analytic calculations of\nstructural and thermodynamic properties.",
        "positive": "Friction controls submerged granular flows: We investigate the coupling between interstitial medium and granular\nparticles by studying the hopper flow of dry and submerged system\nexperimentally and numerically. In accordance with earlier studies, we find,\nthat the dry hopper empties at a constant rate. However, in the submerged\nsystem we observe the surging of the flow rate. We model both systems using the\ndiscrete element method, which we couple with computational fluid dynamics in\nthe case of a submerged hopper. We are able to match the simulations and the\nexperiments with good accuracy. To do that, we fit the particle-particle\ncontact friction for each system separately, finding that submerging the hopper\nchanges the particle-particle contact friction from $\\mu_{vacuum}=0.15$ to\n$\\mu_{sub}=0.13$, while all the other simulation parameters remain the same.\nFurthermore, our experiments find a particle size dependence to the flow rate,\nwhich is comprehended based on arguments on the terminal velocity and drag.\nThese results jointly allow us to conclude that at the large particle limit,\nthe interstitial medium does not matter, in contrast to small particles. The\nparticle size limit, where this occurs depends on the viscosity of the\ninterstitial fluid."
    },
    {
        "anchor": "Soft matter physics of the ground beneath our feet: Inspired by presentations by the authors during a workshop organized at the\nPrinceton Center for Theoretical Science (PCTS) in January 2022, we present a\nperspective on some of the outstanding questions related to the \"physics of the\nground beneath our feet.\" These identified challenges are intrinsically shared\nwith the field of Soft Matter but also have unique aspects when the natural\nenvironment is studied.",
        "positive": "Clustering and phase separation of circle swimmers dispersed in a\n  monolayer: We perform Brownian dynamics simulations in two dimensions to study the\ncollective behavior of circle swimmers, which are driven by both, an\n(effective) translational and rotational self-propulsion, and interact via\nsteric repulsion. We find that active rotation generally opposes\nmotility-induced clustering and phase separation, as demonstrated by a\nnarrowing of the coexistence region upon increase of the propulsion angular\nvelocity. Moreover, although the particles are intrinsically assigned to rotate\ncounterclockwise, a novel state of clockwise vortices emerges at an optimal\nvalue of the effective propulsion torque. We propose a simple gear-like model\nto capture the underlying mechanism of the clockwise vortices."
    },
    {
        "anchor": "Role of evaporation rate on the particle organization and crack patterns\n  obtained by drying a colloidal layer: -- A scientific hurdle in manufacturing solid films by drying colloidal\nlayers is preventing them from fracturing. This paper examines how the drying\nrate of colloidal liquids influences the particle packing at the nanoscale in\ncorrelation with the crack patterns observed at the macroscale. Increasing the\ndrying rate results in more ordered, denser solid structures, and the dried\nsamples have more cracks.Yet, introducing a holding period (at a prescribed\npoint) during the drying protocol results in a more disordered solid structure\nwith significantly less cracks. To interpret these observations, this paper\nconjectures that a longer drying protocol favors the formation of aggregates.\nIt is further argued that the number and size of the aggregates increase as the\ndrying rate decreases. This results in the formation of a more disordered,\nporous film from the viewpoint of the particle packing, and a more resistant\nfilm, i.e. less cracks, from the macroscale viewpoint.",
        "positive": "Steady state in a gas of inelastic rough spheres heated by a uniform\n  stochastic force: We study here the steady state attained in a granular gas of inelastic rough\nspheres that is subject to a spatially uniform random volume force. The\nstochastic force has the form of the so-called white noise and acts by adding\nimpulse to the particle translational velocities. We work out an analytical\nsolution of the corresponding velocity distribution function from a Sonine\npolynomial expansion that displays energy non-equipartition between the\ntranslational and rotational modes, translational and rotational kurtoses, and\ntranslational-rotational velocity correlations. By comparison with a numerical\nsolution of the Boltzmann kinetic equation (by means of the Direct Simulation\nMonte Carlo method) we show that our analytical solution provides a good\ndescription that is quantitatively very accurate in certain ranges of\ninelasticity and roughness. We also find three important features that make the\nforced granular gas steady state very different from the homogeneous cooling\nstate (attained by an unforced granular gas). First, the marginal velocity\ndistributions are always close to a Maxwellian. Second, there is a continuous\ntransition to the purely smooth limit (where the effects of particle rotations\nare ignored). And third, the angular translational-rotational velocity\ncorrelations show a preference for a quasiperpendicular mutual orientation\n(which is called \"lifted-tennis-ball\" behavior)."
    },
    {
        "anchor": "Flow rate of polygonal grains through a bottleneck: Interplay between\n  shape and size: We report two-dimensional simulations of circular and polygonal grains\npassing through an aperture at the bottom of a silo. The mass flow rate for\nregular polygons is lower than for disks as observed by other authors. We show\nthat both the exit velocity of the grains and the packing fraction are lower\nfor polygons, which leads to the reduced flow rate. We point out the importance\nof the criteria used to define when two objects of different shape are\nconsidered to be of the same size. Depending on this criteria, the mass flow\nrate may vary significantly for some polygons. Moreover, the particle flow rate\nis non-trivially related to a combination of mass flow rate, particle shape and\nparticle size. For some polygons, the particle flow rate may be lower or higher\nthan that of the corresponding disks depending on the size comparison criteria.",
        "positive": "Electrotaxis of self-propelling artificial swimmers in microchannels: Ciliated microswimmers and flagellated bacteria alter their swimming\ntrajectories to follow the direction of an applied electric field exhibiting\nelectrotaxis. Both for matters of application and physical modelling, it is\ninstructive to study such behaviour in synthetic swimmers. We show here that\nunder an external electric field, self-propelling active droplets autonomously\nmodify their swimming trajectories in microchannels, even undergoing `U-turns',\nto exhibit robust electrotaxis. Depending on the relative initial orientations\nof the microswimmer and the external electric field, the active droplet can\nalso navigate upstream of an external flow following a centre-line motion,\ninstead of the oscillatory upstream trajectory observed in absence of electric\nfield. Using a hydrodynamic theory model, we show that the electrically induced\nangular velocity and electrophoretic effects, along with the microswimmer\nmotility and its hydrodynamic interactions with the microchannel walls, play\ncrucial roles in dictating the electrotactic trajectories and dynamics.\nSpecifically, the transformation in the trajectories during upstream swimming\nagainst an external flow under an electric field can be understood as a reverse\nHopf bifurcation for a dynamical system. Our study provides a simple\nmethodology and a systematic understanding of manoeuvring active droplets in\nmicroconfinements for micro-robotic applications especially in biotechnology."
    },
    {
        "anchor": "Interpenetration of fractal clusters drives elasticity in colloidal gels\n  formed upon flow cessation: Colloidal gels are out of equilibrium soft solids composed of attractive\nBrownian particles that form a space-spanning network at low volume fractions.\nThe elastic properties of these systems result from the network microstructure,\nwhich is very sensitive to shear history. Here, we take advantage of such\nsensitivity to tune the viscoelastic properties of a colloidal gel made of\ncarbon black nanoparticles. Starting from a fluidized state under an applied\nshear rate $\\dot \\gamma_0$, we use an abrupt flow cessation to trigger a\nliquid-to-solid transition. We observe that the resulting gel is all the more\nelastic when the shear rate $\\dot \\gamma_0$ is low and that the viscoelastic\nspectra can be mapped on a master curve. Moreover, coupling rheometry to small\nangle X-ray scattering allows us to show that the gel microstructure is\ndifferent from gels solely formed by thermal agitation where only two length\nscales are observed: the dimension of the colloidal and the dimension the\nfractal aggregates. Competition between shear and thermal energy leads to gels\nwith three characteristic length scales. Such gels structure in a percolated\nnetwork of fractal clusters that interpenetrate each other. Experiments on gels\nprepared with various shear histories reveal that cluster interpenetration\nincreases with decreasing values of the shear rate $\\dot \\gamma_0$ applied\nbefore flow cessation. These observations strongly suggest that cluster\ninterpenetration drives the gel elasticity, which we confirm using a structural\nmodel. Our results, which are in stark contrast with previous literature, where\ngel elasticity was either linked to cluster connectivity or to bending modes,\nhighlight a novel local parameter controlling the macroscopic viscoelastic\nproperties of colloidal gels.",
        "positive": "Encoding Gaussian curvature in glassy and elastomeric liquid crystal\n  polymer networks: Considerable recent attention has been given to the study of shape formation\nusing modern responsive materials that can be preprogrammed to undergo\nspatially inhomogeneous local deformations. In particular, nematic liquid\ncrystal polymer networks offer exciting possibilities in this context. In this\npaper, we discuss the generation of Gaussian curvature in thin nematic sheets\nusing smooth in-plane director fields patterned across the surface. We\nhighlight specific patterns which encode constant Gaussian curvature of\nprescribed sign and magnitude and present experimental results which appear to\nsupport the theoretical predictions. Specifically, we provide experimental\nevidence for the realization of positive and negative Gaussian curvature in\nglassy and elastomeric liquid crystal polymer networks through the stimulation\nof smoothly varying in-plane director fields."
    },
    {
        "anchor": "Impact of surface roughness on liquid-liquid transition: Liquid-liquid transition (LLT) in single-component liquids is one of the most\nmysterious phenomena in condensed matter. So far this problem has attracted\nattention mainly from the purely scientific viewpoint. Here we report the first\nexperimental study on an impact of surface nano-structuring on LLT by using a\nsurface treatment called rubbing, which is the key technology for the\nproduction of liquid crystal displays. We find that such a rubbing treatment\nhas a significant impact on the kinetics of liquid-liquid transition (LLT) of\nan isotropic molecular liquid, triphenyl phosphite. For a liquid confined\nbetween rubbed surfaces, surface-induced barrier-less formation of the liquid\nII phase is observed even in a metastable state, where there should be a\nbarrier for nucleation of the liquid II phase in bulk. Thus, surface rubbing of\nsubstrates not only changes the ordering behavior, but also accelerates the\nkinetics significantly. This spatio-temporal pattern modulation of LLT can be\nexplained by a wedge filling transition and the resulting drastic reduction of\nthe nucleation barrier. However, this effect completely disappears in the\nunstable (spinodal) regime, indicating the absence of the activation barrier\neven for bulk LLT. This confirms the presence of nucleation-growth-type and\nspinodal-decomposition-type LLT, supporting that LLT is truly a first-order\ntransition with criticality. Our finding also opens up a new way to control the\nkinetics of LLT of a liquid confined in a solid cell by structuring its surface\non a mesoscopic lengthscale, which may contribute to making LLT useful for\nmicro-fluidics and other industrial applications.",
        "positive": "Copolymer-induced stabilizing effect of highly swollen hexagonal\n  mesophases: We show quantitatively that tiny amounts of copolymer that decorate a\noil/water interfaces can greatly enhance the stability of swollen surfactant\nhexagonal phases, comprising oil tubes regularly arranged in a water matrix.\nSuch soft composite materials, whose both radius of the tubes and water channel\nbetween the tubes can be controlled independently over large ranges, offer a\npotential interest for the synthesis of mesoporous materials."
    },
    {
        "anchor": "Dependence of phase behavior and surface tension on particle stiffness\n  for active Brownian particles: We study quasi two-dimensional, monodisperse systems of active Brownian\nparticles (ABPs) for a range of activities, stiffnesses, and densities. We\ndevelop a microscopic, analytical method for predicting the dense phase\nstructure formed after motility-induced phase separation (MIPS) has occurred,\nincluding the dense cluster's area fraction, interparticle pressure, and\nradius. Our predictions are in good agreement with our Brownian dynamics\nsimulations. We, then, derive a continuum model to investigate the relationship\nbetween the predicted interparticle pressure, the swim pressure, and the\nmacroscopic pressure in the momentum equation. We find that formulating the\npoint-wise macroscopic pressure as the interparticle pressure and modeling the\nparticle activity through a spatially variant body force -- as opposed to a\nvolume-averaged swim pressure -- results in consistent predictions of pressure\nin both the continuum model and the microscopic theory. This formulation of\npressure also results in nearly zero surface tension for the phase separated\ndomains, irrespective of activity, stiffness, and area fraction. Furthermore,\nusing Brownian dynamics simulations and our continuum model, we showed that\nboth the interface width and surface tension, are intrinsic characteristics of\nthe system. On the other hand, if we were to exclude the body force induced by\nactivity, we find that the resulting surface tension values are linearly\ndependent on the size of the simulation, in contrast to the statistical\nmechanical definition of surface tension.",
        "positive": "Active elastic dimers: Cells moving on rigid tracks: Experiments suggest that the migration of some cells in the three-dimensional\nextra cellular matrix bears strong resemblance to one-dimensional cell\nmigration. Motivated by this observation, we construct and study a minimal\none-dimensional model cell made of two beads and an active spring moving along\na rigid track. The active spring models the stress fibers with their\nmyosin-driven contractility and alpha-actinin-driven extendability, while the\nfriction coefficients of the two beads describe the catch/slip bond behavior of\nthe integrins in focal adhesions. In the absence of active noise, net motion\narises from an interplay between active contractility (and passive\nextendability) of the stress fibers and an asymmetry between the front and back\nof the cell due to catch bond behavior of integrins at the front of the cell\nand slip bond behavior of integrins at the back. We obtain reasonable cell\nspeeds with independently estimated parameters. We also study the effects of\nhysteresis in the active spring, due to catch bond behavior and the dynamics of\ncross-linking, and the addition of active noise on the motion of the cell. Our\nmodel highlights the role of alpha-actinin in three-dimensional cell motility\nand does not require Arp2/3 actin filament nucleation for net motion."
    },
    {
        "anchor": "A Reduced Model for a Phoretic Swimmer: We consider a 2D model of an autophoretic particle in which the particle has\na circular shape and emits/absorbs a solute that diffuses and is advected by\nthe suspending fluid. Beyond a certain emission/absorption rate (characterized\nby a dimensionless P\\'eclet number, $Pe$) the particle is known to undergo a\nbifurcation from a non motile to a motile state, with different trajectories,\ngoing from a straight to circular and to a chaotic motion by progressively\nincreasing $Pe$. From the full model involving solute diffusion and advection,\nwe derive a reduced closed model which involves only two time-dependent\namplitudes $C_1(t)$ and $C_2(t)$ corresponding to the first two Fourier modes\nof the solute concentration field. This model consists of two coupled nonlinear\nordinary differential equations for $C_1$ and $C_2$ and presents several great\nadvantages:(i) the straight and circular motions can be handled fully\nanalytically, (ii) complex motions such as chaos can be analyzed numerically\nvery efficiently in comparison to the numerically expensive full model\ninvolving partial differential equations, (iii) the reduced model has a\nuniversal form dictated only by symmetries, (iv) the model can be extended to\nhigher Fourier modes. The derivation method is exemplified for a 2D model, for\nsimplicity, but can easily be extended to 3D, not only for the presently\nselected phoretic model, but also for any model in which chemical activity\ntriggers locomotion. A typical example can be found, for example, in the field\nof cell motility involving acto-myosin kinetics. This strategy offers an\ninteresting way to cope with swimmers on the basis of ordinary differential\nequations, allowing for analytical tractability and efficient numerical\ntreatment.",
        "positive": "Effect of flow-induced molecular alignment on welding and strength of\n  polymer interfaces: Structures formed by fused filament fabrication are often substantially\nweaker than those made with conventional techniques, and fail at the welds\nbetween successive layers. One factor that may influence strength is\nflow-induced alignment of deposited material. Recent work suggests that\nalignment reduces the entanglement density and thus should accelerate welding\nby diffusion. Here, coarse-grained molecular simulations are used to test the\neffect of molecular alignment on diffusion and weld strength. While standard\nmeasures show a decrease of the entanglement density with alignment, there is\nno change in the rate of diffusion normal to the interface or the rate of\nformation of entanglements across the interface. The time for chain\nreorientation also remains equal to the equilibrium disentanglement time\n$\\tau_d$. Despite this, simulations of mechanical tests show that welds formed\nfrom aligned states are weaker until several $\\tau_d$. This is not because the\nweld itself is weaker, but because aligned material near the weld is weaker\nthan unaligned material. The maximum shear strength and tensile fracture energy\nof welded systems are the same as bulk systems with the same alignment."
    },
    {
        "anchor": "Lipid membranes with an edge: Consider a lipid membrane with a free exposed edge. The energy describing\nthis membrane is quadratic in the extrinsic curvature of its geometry; that\ndescribing the edge is proportional to its length. In this note we determine\nthe boundary conditions satisfied by the equilibria of the membrane on this\nedge, exploiting variational principles. The derivation is free of any\nassumptions on the symmetry of the membrane geometry. With respect to earlier\nwork for axially symmetric configurations, we discover the existence of an\nadditional boundary condition which is identically satisfied in that limit. By\nconsidering the balance of the forces operating at the edge, we provide a\nphysical interpretation for the boundary conditions. We end with a discussion\nof the effect of the addition of a Gaussian rigidity term for the membrane.",
        "positive": "Binding branched and linear DNA structures: from isolated clusters to\n  fully bonded gels: The proper design of DNA sequences allows for the formation of well defined\nsupramolecular units with controlled interactions via a consecution of\nself-assembling processes. Here, we benefit from the controlled DNA\nself-assembly to experimentally realize particles with well defined valence,\nnamely tetravalent nanostars (A) and bivalent chains (B). We specifically focus\non the case in which A particles can only bind to B particles, via\nappropriately designed sticky-end sequences. Hence AA and BB bonds are not\nallowed. Such a binary mixture system reproduces with DNA-based particles the\nphysics of poly-functional condensation, with an exquisite control over the\nbonding process, tuned by the ratio, r, between B and A units and by the\ntemperature, T. We report dynamic light scattering experiments in a window of\nTs ranging from 10{\\deg}C to 55{\\deg}C and an interval of r around the\npercolation transition to quantify the decay of the density correlation for the\ndifferent cases. At low T, when all possible bonds are formed, the system\nbehaves as a fully bonded network, as a percolating gel and as a cluster fluid\ndepending on the selected r."
    },
    {
        "anchor": "Influence of anisotropic surface roughness on lubricated rubber friction\n  with application to hydraulic seals: Machine elements and mechanical components have often surfaces with\nanisotropic roughness, which may result from the machining processes, e.g.\ngrinding, or from wear. Hence, it is important to understand how surface\nroughness anisotropy affects contact mechanics properties, such as friction and\nthe interface separation, which is important for lubricated contacts. Here we\nextend and apply a multiscale mean-field model to the lubricated contact\nbetween a soft (e.g. rubber) elastic solid and a rigid countersurface. We\nconsider surfaces with anisotropic surface roughness, and discuss how the fluid\nflow factors and friction factors depend on the roughness. We present an\nexperimental study of the lubricated sliding contact between a nitrile\nbutadiene rubber O-ring and steel surfaces with different types of isotropic\nand anisotropic surface roughness. The good quantitative comparison between the\nexperimental results and the theory predictions suggests that the multiscale\nlubrication mechanisms are accurately captured by the theory.",
        "positive": "Surface Tension Effects on Surface Instabilities of Dielectric\n  Elastomers: Dielectric elastomers have recently been proposed for various\nbiologically-relevant applications, in which they may operate in fluidic\nenvironments where surface tension effects may have a significant effect on\ntheir stability and reliability. Here, we present a theoretical analysis\ncoupled with computational modeling for a generalized electromechanical\nanalysis of surface stability in dielectric elastomers accounting for surface\ntension effects. For mechanically deformed elastomers, significant increases in\ncritical strain and instability wavelength are observed for small\nelastocapillary numbers. When the elastomers are deformed electrostatically,\nboth surface tension and the amount of pre-compression are found to\nsubstantially increase the critical electric field while decreasing the\ninstability wavelength."
    },
    {
        "anchor": "Nonequilibrium fluctuation dissipation relations of interacting Brownian\n  particles driven by shear: We present a detailed analysis of the fluctuation dissipation theorem (FDT)\nclose to the glass transition in colloidal suspensions under steady shear using\nmode coupling approximations. Starting point is the many-particle Smoluchowski\nequation. Under shear, detailed balance is broken and the response functions in\nthe stationary state are smaller at long times than estimated from the\nequilibrium FDT. An asymptotically constant relation connects response and\nfluctuations during the shear driven decay, restoring the form of the FDT with,\nhowever, a ratio different from the equilibrium one. At short times, the\nequilibrium FDT holds. We follow two independent approaches whose results are\nin qualitative agreement. To discuss the derived fluctuation dissipation\nratios, we show an exact reformulation of the susceptibility which contains not\nthe full Smoluchowski operator as in equilibrium, but only its well defined\nHermitian part. This Hermitian part can be interpreted as governing the\ndynamics in the frame comoving with the probability current. We present a\nsimple toy model which illustrates the FDT violation in the sheared colloidal\nsystem.",
        "positive": "Osmotic Swelling Behavior of Surface-Charged Ionic Microgels: In recent years, ionic microgels have garnered much attention due to their\nunique properties, especially their stimulus-sensitive swelling behavior. The\ntunable response of these soft, permeable, compressible, charged colloidal\nparticles is increasingly attractive for applications in medicine and\nbiotechnologies, such as controlled drug delivery, tissue engineering, and\nbiosensing. The ability to model and predict variation of the osmotic pressure\nof a single microgel with respect to changes in particle properties and\nenvironmental conditions proves vital to such applications. In this work, we\napply both nonlinear Poisson-Boltzmann theory and molecular dynamics simulation\nto ionic microgels (macroions) in the cell model to compute density profiles of\nmicroions (counterions, coions), single-microgel osmotic pressure, and\nequilibrium swelling ratios of spherical microgels whose fixed charge is\nconfined to the macroion surface. The basis of our approach is an exact theorem\nthat relates the electrostatic component of the osmotic pressure to the\nmicroion density profiles. Close agreement between theory and simulation serves\nas a consistency check to validate our approach. We predict that\nsurface-charged microgels progressively deswell with increasing microgel\nconcentration, starting well below close packing, and with increasing salt\nconcentration, in qualitative agreement with experiments. Comparison with\nprevious results for microgels with fixed charge uniformly distributed over\ntheir volume demonstrates that surface-charged microgels deswell more rapidly\nthan volume-charged microgels. We conclude that swelling behavior of ionic\nmicrogels in solution is sensitive to the distribution of fixed charge within\nthe polymer-network gel and strongly depends on bulk concentrations of both\nmicrogels and salt ions."
    },
    {
        "anchor": "Microfluidic pump driven by anisotropic phoresis: Fluid flow along microchannels can be induced by keeping opposite walls at\ndifferent temperatures, and placing elongated tilted pillars inside the\nchannel. The driving force for this fluid motion arises from the anisotropic\nthermophoretic effect of the elongated pillars that generates a force parallel\nto the walls, and perpendicular to the temperature gradient. The force is not\ndetermined by the thermophilic or thermophobic character of the obstacle\nsurface, but by the geometry and the thermophoretic anisotropy of the obstacle.\nVia mesoscale hydrodynamic simulations, we investigate the pumping properties\nof the device as a function of the channel geometry, and pillar surface\nproperties. Applications as fluidic mixers, and fluid alternators are also\noutlined, together with the potential use of all these devices to harvest waste\nheat energy. Furthermore, similar devices can be also built employing\ndiffusiophoresis or electrophoresis.",
        "positive": "Determining Hydration Level in Self-Assembled Structures Using Contrast\n  Variation Small Angle Neutron Scattering: We outline a strategy for quantitatively evaluating the conformational\ncharacteristics of self-assembled structures using the techniques of contrast\nvariation small angle neutron scattering. By means of basis function expansion,\na case study of spherical micelles demonstrates that the intra-particle\nhydration and polymer distributions can be determined from the coherent\nscattering intensity in a model-free manner. Our proposed approach is simple,\nanalytical and does not require a presumptive hypothesis of scattering function\nas an input in data analysis. The successful implementation of the proposed\napproach opens the prospect of quantifying the nanoscale complexity of soft\nmatter using neutron scattering."
    },
    {
        "anchor": "Effects of particle compressibility on structural and mechanical\n  properties of compressed soft granular materials: Changes in the mechanical properties of granular materials, induced by\nvariations in the intrinsic compressibility of the particles, are investigated\nby means of numerical simulations based on the combination of the Finite\nElement and Contact Dynamics methods. Assemblies of athermal 2D particles are\nsubjected to quasi-static uni-axial compactions up to packing fractions close\nto $1$. Inspired by the contact mechanics in the Hertz's limit, we show that\nthe effect of the compressibility of the particles both on the global and the\nlocal stresses, can be described by considering only the packing fraction of\nthe system. This result, demonstrated in the whole range of accessible packing\nfractions in case of frictionless particles, remains relevant for moderate\ninter-particles coefficients of friction. The small discrepancies observed with\nfrictional particles originate from irreversible local reorganizations in the\nsystem, the later being facilitated by the compressibility of the particles.",
        "positive": "Charge regulation of nonpolar colloids: Individual colloids often carry a charge as a result of the dissociation (or\nadsorption) of weakly-ionized surface groups. The magnitude depends on the\nprecise chemical environment surrounding a particle, which in a concentrated\ndispersion is a function of the colloid packing fraction $\\eta$. Theoretical\nstudies have suggested that the effective charge $Z_{\\rm{eff}}$ in regulated\nsystems could, in general, decrease with increasing $\\eta$. We test this\nhypothesis for nonpolar dispersions by determining $Z_{\\rm{eff}}(\\eta)$ over a\nwide range of packing fractions ($10^{-5} \\le \\eta \\le 0.3$) using a\ncombination of small-angle X-ray scattering and electrophoretic mobility\nmeasurements. We find a complex dependence of the particle charge as a function\nof the packing fraction, with $Z_{\\rm{eff}}$ initially decreasing at low\nconcentrations before finally increasing at high $\\eta$. We attribute the\nnon-monotonic density dependence to a crossover from concentration-independent\nscreening at low $\\eta$, to a high packing fraction regime in which counterions\noutnumber salt ions and electrostatic screening becomes $\\eta$-dependent. The\nefficiency of charge stabilization at high concentrations may explain the\nunusually high stability of concentrated nanoparticle dispersions which has\nbeen reported."
    },
    {
        "anchor": "Chirality-induced helical self-propulsion of cholesteric liquid crystal\n  droplets: We report the first experimental realization of a chiral artificial\nmicroswimmer exhibiting the helical motion. We found that a cholesteric liquid\ncrystal droplet with a helical director field swims in a helical path driven by\nthe Marangoni flow in an aqueous surfactant solution. We confirmed that the\nhandedness of the droplet determines that of the helical path. This result\nstrongly suggests that the helical motion is originated from the chirality of\nthe cholesteric liquid crystal. To study the mechanism of the emergence of the\nhelical motion, we propose a coupled time-evolution equations in terms of a\nvelocity, an angular velocity and a tensor variable representing the symmetry\nof the helical director field of the droplet. Our model shows that the chiral\ncoupling terms between the velocity and the angular velocity play a crucial\nrole in the emergence of the helical swimming of the droplet.",
        "positive": "Breaking of scale-invariance symmetry in adsorption processes: Standard models of sequential adsorption are implicitly formulated in a {\\em\nscale invariant} form, by assuming adsorption on an infinite surface, with no\ncharacteristic length scales. In real situations, however, involving complex\nsurfaces, intrinsic length scales may be relevant. We present an analytic model\nof continuous random sequential adsorption, in which the scale invariance\nsymmetry is explicitly broken. The characteristic length is imposed by a set of\nscattered obstacles, previously adsorbed onto the surface. We show, by means of\nanalytic solutions and numerical simulations, the profound effects of the\nsymmetry breaking on both the jamming limit and the correlation function of the\nadsorbed layer."
    },
    {
        "anchor": "Temperature phase transition model for the DNA-CNTs-based nanotweezers: DNA and Carbon nanotubes (CNTs) have unique physical, mechanical and\nelectronic properties that make them revolutionary materials for advances in\ntechnology. In state-of-the-art applications, these physical properties can be\nexploited to design a type of bio-nanorobot. In this paper, we present the\nbehaviors of DNA-based nanotweezers and show the capabilities of controlling\nthe robotic device. The theoretical calculations are based on the\nEnglander-Peyrard-Bishop model for DNA. Furthermore, the influence of the\nCasimir force between on the opening and closing of nanotweezers is studied in\ncomparison with the stretching forces of DNA.",
        "positive": "Modelling Washboard Road: from experimental measurements to linear\n  stability analysis: When submitted to the repeated passages of vehicles unpaved roads made of\nsand or gravel can develop a ripply pattern known as washboard or corrugated\nroad. We propose a stability analysis based on experimental measurements of the\nforce acting on a blade (or plow) dragged on a circular sand track and show\nthat a linear model is sufficient to describe the instability near onset. The\nrelation between the trajectory of the plow and the profile of the sand bed\nleft after its passage is studied experimentally. The various terms in the\nexpression of the lift force created by the flow of granular material on the\nplow are determined up to first order by imposing a sinusoidal trajectory to\nthe blade on an initially flat sand bed, as well as by imposing a horizontal\ntrajectory on an initially rippled sand bed. Our model recovers all the\npreviously observed features of washboard road and accurately predicts the most\nunstable wavelength near onset as well as the critical velocity for the\ninstability."
    },
    {
        "anchor": "Hydrodynamic fluctuations and instabilities in ordered suspensions of\n  self-propelled particles: We construct the hydrodynamic equations for {\\em suspensions} of\nself-propelled particles (SPPs) with spontaneous orientational order, and make\na number of striking, testable predictions:(i) SPP suspensions with the\nsymmetry of a true {\\em nematic} are {\\em always} absolutely unstable at long\nwavelengths.(ii) SPP suspensions with {\\em polar}, i.e., head-tail {\\em\nasymmetric}, order support novel propagating modes at long wavelengths,\ncoupling orientation, flow, and concentration. (iii) In a wavenumber regime\naccessible only in low Reynolds number systems such as bacteria, polar-ordered\nsuspensions are invariably convectively unstable.(iv) The variance in the\nnumber N of particles, divided by the mean <N>, diverges as $<N >^{2/3}$ in\npolar-ordered SPP suspensions.",
        "positive": "Comment on ''Minimal Surfaces, Screw Dislocations, and Twist Grain\n  Boundaries'': In a recent letter, (Phys. Rev. Lett. 82, 2892(1999); cond-mat/9808306)\nKamien and Lubensky calculated the energy of the surface constructed via a\nlinear superposition of screw dislocations in SmA phase, and obtained the\npositive (repulsive) sign of the long-range interaction between dislocations.\nWe would like to object that this interaction is attractive. This conclusion\ncan be important to explain the discontinuity of the TGB - SmA phase transition\nin chiral liquid crystals."
    },
    {
        "anchor": "Hydrodynamic Enhancement of $p$-atic Defect Dynamics: We investigate numerically and analytically the effects of hydrodynamics on\nthe dynamics of topological defects in $p-$atic liquid crystals, i.e.\ntwo-dimensional liquid crystals with $p-$fold rotational symmetry. Importantly,\nwe find that hydrodynamics fuels a generic passive self-propulsion mechanism\nfor defects of winding number $s=(p-1)/p$ and arbitrary $p$. Strikingly, we\ndiscover that hydrodynamics always accelerates the annihilation dynamics of\npairs of $\\pm 1/p$ defects, and that, contrary to expectations, this effect\nincreases with $p$. Our Letter paves the way towards understanding cell\nintercalation and other remodelling events in epithelial layers.",
        "positive": "Long Range Correlation in Granular Shear Flow II: Theoretical\n  Implications: Numerical simulations are used to test the kinetic theory constitutive\nrelations of inertial granular shear flow. These predictions are shown to be\naccurate in the dilute regime, where only binary collisions are relevant, but\nunderestimate the measured value in the dense regime, where force networks of\nsize $\\xi$ are present. The discrepancy in the dense regime is due to\nnon-collisional forces that we measure directly in our simulations and arise\nfrom elastic deformations of the force networks. We model the non-collisional\nstress by summing over all paths that elastic waves travel through force\nnetworks. This results in an analytical theory that successfully predicts the\nstress tensor over the entire inertial regime without any adjustable\nparameters."
    },
    {
        "anchor": "Topological Description of the Solidification of Undercooled Fluids and\n  the Temperature Dependence of the Thermal Conductivity of Crystalline and\n  Glassy Solids Above Approximately 50 K: By the adoption of a quaternion orientational order parameter to describe\nsolidification, the topological origins of the thermal transport properties of\ncrystalline and non-crystalline solid states are considered herein. Global\norientational order, achieved by spontaneous symmetry breaking, is prevented at\nfinite temperatures for systems that exist in restricted dimensions\n(Mermin-Wagner theorem). Just as complex ordered systems exist in restricted\ndimensions in 2D and 1D, owing to the dimensionality of the order parameter,\nquaternion ordered systems in 4D and 3D exist in restricted dimensions. Just\nbelow the melting temperature, misorientational fluctuations in the form of\nspontaneously generated topological defects prevent the development of the\nsolid state. Such solidifying systems are well-described using O(4) quantum\nrotor models, and a defect-driven Berezinskii-Kosterlitz-Thouless (BKT)\ntransition is anticipated to separate an undercooled fluid from a crystalline\nsolid state. In restricted dimensions, in addition to orientationally-ordered\nground states, orientationally-disordered ground states may be realized by\ntuning a non-thermal parameter in the relevant O(n) quantum rotor model\nHamiltonian; thus, glassy solid states are anticipated to exist as distinct\nground states of O(4) quantum rotor models. Within this topological framework\nfor solidification, the finite Kauzmann temperature marks a first-order\ntransition between crystalline and glassy solid states at a \"self-dual critical\npoint\" that belongs to O(4) quantum rotor models. This transition is a\nhigher-dimensional analogue to the quantum phase transition that belongs to\nO(2) Josephson junction arrays (JJAs). Thermal transport properties of\ncrystalline and glassy solid states, above approximately 50 K, are considered\nalongside electrical transport properties of JJAs across the\nsuperconductor-to-superinsulator transition.",
        "positive": "Slow time scales in a dense vibrofluidized granular material: Modeling collective motion in non-conservative systems, such as granular\nmaterials, is difficult since a general microscopic-to-macroscopic approach is\nnot available: there is no Hamiltonian, no known stationary densities in phase\nspace, not a known small set of relevant variables. Phenomenological\ncoarse-grained models are a good alternative, provided that one has identified\na few slow observables and collected a sufficient amount of data for their\ndynamics. Here we study the case of a vibrofluidized dense granular material.\nThe experimental study of a tracer, dispersed into the media, showed the\nevidence of many time scales: fast ballistic, intermediate caged, slow\nsuperdiffusive, very slow diffusive. A numerical investigation has demonstrated\nthat tracer's superdiffusion is related to slow rotating drifts of the granular\nmedium. Here we offer a deeper insight into the slow scales of the granular\nmedium, and propose a new phenomenological model for such a \"secular\" dynamics.\nBased upon the model for the granular medium, we also introduce a model for the\ntracer (fast and slow) dynamics, which consists in a stochastic system of\nequations for three coupled variables, and is therefore more refined and\nsuccessful than previous models."
    },
    {
        "anchor": "Viscoelastic properties of attractive and repulsive colloidal glasses: We report a numerical study of the shear viscosity and the frequency\ndependent elastic moduli close to dynamical arrest for a model of short-range\nattractive colloids, both for the repulsive and the attractive glass\ntransition. Calculating the stress autocorrelation functions, we find that\ndensity fluctuations of wavevectors close to the first peak in the structure\nfactor control the viscosity rise on approaching the repulsive glass, while\nfluctuations of larger wavevectors control the viscosity close to the\nattractive glass. On approaching the glass transition, the viscosity diverges\nwith a power law with the same exponent as the density autocorrelation time.",
        "positive": "A path integral approximation of conditional probability densities with\n  application to stochastic elastic rods: In this work, we generalise Gelfand-Yaglom-type methods in the vector case\nfor the computation of Gaussian path integrals. The extension we propose allows\nto consider general second variation operators subject to different boundary\nconditions and to regularise the divergence in presence of zero modes. The\nderived methods are exploited to study the statistical physics of polymers at\nthermodynamic equilibrium (e.g. DNA). The energy of equilibria combined with\nsuitable Jacobi field determinants can be used to estimate the distribution of\nend-to-end displacements when the filament is interacting with a heat bath. In\nthe continuum limit of Cosserat elastic rods, we demonstrate how to derive\napproximate conditional probability density functions governing the relative\nlocation and orientation of the two ends, first for the looping problem and\nsecond when the rod is subject to a prescribed external end-loading, in\naddition to external stochastic forcing. For isotropic Cosserat rods, certain\nlooping boundary value problems admit non-isolated families of critical points\nof the energy due to an associated continuous symmetry, and the standard\nLaplace method fails for the presence of zero modes. Taking inspiration from\n(imaginary) path integral techniques, we show how a quantum mechanical\nprobabilistic treatment of Goldstone modes in statistical rod mechanics sheds\nlight on J-factor computations for isotropic rods in the semi-classical\ncontext. All the results are achieved exploiting appropriate Jacobi fields\narising from Gaussian path integrals, and show good agreement when compared\nwith intense Monte Carlo simulations for the target examples."
    },
    {
        "anchor": "On the Nature of the Debye-Process in Monohydroxy Alcohols:\n  5-Methyl-2-Hexanol Investigated by Depolarized Light Scattering and\n  Dielectric Spectroscopy: The slow Debye-like relaxation in the dielectric spectra of monohydroxy\nalcohols is a matter of long standing debate. In the present work, we probe\nreorientational dynamics of 5-methyl-2-hexanol with dielectric spectroscopy and\ndepolarized light scattering (DDLS) in the supercooled regime. While in a\nprevious study of a primary alcohol no indication of the Debye peak in the DDLS\nspectra was found, we now for the first time report clear evidence of a Debye\ncontribution in a monoalcohol in DDLS. A quantitative comparison between the\ndielectric and DDLS manifestation of the Debye peak reveals that while the\ndielectric Debye process represents fluctuations in the end-to-end vector\ndipole moment of the transient chains, its occurrence in DDLS shows a more\nlocal signature and is related to residual correlations which occur due to a\nslight anisotropy of the $\\alpha$-relaxation caused by the chain formation.",
        "positive": "Stress Relaxation of Entangled Polymer Networks: The non-linear stress-strain relation for crosslinked polymer networks is\nstudied using molecular dynamics simulations. Previously we demonstrated the\nimportance of trapped entanglements in determining the elastic and relaxational\nproperties of networks. Here we present new results for the stress versus\nstrain for both dry and swollen networks. Models which limit the fluctuations\nof the network strands like the tube model are shown to describe the stress for\nboth elongation and compression. For swollen networks, the total modulus is\nfound to decrease like (V_0/V)^{2/3} and goes to the phantom model result only\nfor short strand networks."
    },
    {
        "anchor": "Two-stage crystallization of charged colloids at low supersaturations: We report simulations on the homogeneous liquid-fcc nucleation of charged\ncolloids for both low and high contact energy values. As a precursor for\ncrystal formation, we observe increased local order at the position where the\ncrystal will form, but no correlations with the local density. Thus, the\nnucleation is driven by order fluctuations rather than density fluctuations.\nOur results also show that the transition involves two stages in both cases,\nfirst a transition liquid-bcc, followed by a bcc-hcp/fcc transition. Both\ntransitions have to overcome free energy barriers, so that a spherical bcc-like\ncluster is formed first, in which the final fcc-like structure is nucleated\nmainly at the surface of the crystallite. This means that the bcc-fcc phase\ntransition is a heterogeneous nucleation, even though we start from a\nhomogeneous bulk liquid. The height of the bcc-hcp/fcc free energy barrier\nstrongly depends on the contact energies of the colloids. For low contact\nenergy this barrier is low, so that the bcc-hcp/fcc transition happens\nspontaneously. For the higher contact energy, the second barrier is too high to\nbe crossed spontaneously by the colloidal system. However, it was possible to\nratchet the system over the second barrier and to transform the bcc nuclei into\nthe stable hcp/fcc phase. The transitions are dominated by the first liquid-bcc\ntransition and can be described by Classical Nucleation Theory using an\neffective surface tension.",
        "positive": "Crystallization of magnetic dipolar monolayers: a density functional\n  approach: We employ density functional theory to study in detail the crystallization of\nsuper-paramagnetic particles in two dimensions under the influence of an\nexternal magnetic field that lies perpendicular to the confining plane. The\nfield induces non-fluctuating magnetic dipoles on the particles, resulting into\nan interparticle interaction that scales as the inverse cube of the distance\nseparating them. In line with previous findings for long-range interactions in\nthree spatial dimensions, we find that explicit inclusion of liquid-state\nstructural information on the {\\it triplet} correlations is crucial to yield\ntheoretical predictions that agree quantitatively with experiment. A\nnon-perturbative treatment is superior to the oft-employed functional Taylor\nexpansions, truncated at second or third order. We go beyond the usual Gaussian\nparametrization of the density site-orbitals by performing free minimizations\nwith respect to both the shape and the normalization of the profiles, allowing\nfor finite defect concentrations."
    },
    {
        "anchor": "A model of membrane deformations driven by a surface pH gradient: Many cellular organelles are membrane-bound structures with complex membrane\ncomposition and shape. Their shapes have been observed to depend on the\nmetabolic state of the organelle, and the mechanisms that couple biochemical\npathways and membrane shape are still actively investigated. Here, we study a\nmodel coupling inhomogeneities in the lipid composition and membrane geometry\nvia a generalized Helfrich free energy. We derive the resulting stress tensor,\nthe Green's function for a tubular membrane and compute the phase diagram of\nthe induced deformations. We then apply this model to study the deformation of\nmitochondria cristae described as membrane tubes supporting a pH gradient at\nits surface. This gradient in turn controls the lipid composition of the\nmembrane via the protonation/deprotonation of cardiolipins, which are\nacid-based lipids known to be crucial for mitochondria shape and functioning.\nOur model predicts the appearance of tube deformations resembling the observed\nshape changes of cristea when submitted to a proton gradient.",
        "positive": "Photomechanical coupling in photoactive nematic elastomers: Photoactive nematic elastomers are soft rubbery solids that undergo\ndeformation when illuminated. They are made by incorporating photoactive\nmolecules like azobenzene into nematic liquid crystal elastomers. Since its\ninitial demonstration in 2001, it has received increasing interest with many\nrecent studies of periodic and buckling behavior. However, theoretical models\ndeveloped have focused on describing specific deformation modes (e.g., beam\nbending and uniaxial contraction) in the absence of mechanical loads, with only\nlimited attention to the interplay between mechanical stress and light-induced\ndeformation. This paper explores photomechanical coupling in a photoactive\nnematic elastomer under both light illumination and mechanical stress. We begin\nwith a continuum framework built on the free energy developed by Corbett and\nWarner (Phys. Rev. Lett. 2006). Mechanical stress leads to nematic alignment\nparallel to a uniaxial tensile stress. In the absence of mechanical stress, in\nthe photo-stationary state where the system reaches equilibrium, the nematic\ndirector tends to align perpendicular to the polarization of a linearly\npolarized light. However, sufficient illumination can destroy nematic order\nthrough a first-order nematic-isotropic phase transition which is accompanied\nby a snap through deformation. Combined illumination and mechanical stress can\nlead to an exchange of stability accompanied by stripe domains. Finally, the\nstress-intensity phase diagram shows a critical point that may be of interest\nfor energy conversion."
    },
    {
        "anchor": "Hydrodynamic pursuit by cognitive self-steering microswimmers: The properties of biological microswimmers are to a large extent determined\nby fluid-mediated interactions, which govern their propulsion, perception of\ntheir surrounding, and the steering of their motion for feeding or in pursuit.\nTransferring similar functionalities to synthetic microswimmers poses major\nchallenges, and the design of favorable steering and pursuit strategies is\nfundamental in such an endeavor. Here, we apply a squirmer model to investigate\nthe pursuit of pursuer-target pairs with an implicit sensing mechanism and\nlimited hydrodynamic steering abilities of the pursuer. Two hydrodynamic\nsteering strategies are applied for the pursuer's propulsion direction by\nadaptation of its surface flow field, (i) reorientation toward the target with\nlimited maneuverability, and (ii) alignment with the target's propulsion\ndirection combined with speed adaptation. Depending on the nature of the\nmicroswimmer propulsion (puller, pusher) and the velocity-adaptation scheme,\nstable cooperatively moving states can be achieved, characterized by specific\nsquirmer arrangements and controllable trajectories. Importantly, pursuer and\ntarget mutually affect their motion and trajectories.",
        "positive": "Fluctuating stresslets and the viscosity of colloidal suspensions: Theory and simulation of Brownian colloids suspended in an implicit solvent,\nwith the hydrodynamics of the fluid accounted for by effective interactions\nbetween the colloids, are shown to yield a marked and hitherto unobserved\ndiscrepancy between the viscosity calculated from the average shear stress\nunder an imposed shear rate in the Stokesian regime and the viscosity extracted\nby the Green-Kubo formalism from the auto-correlations of thermal stress\nfluctuations in quiescent equilibrium. We show that agreement between both\nmethods is recovered by accounting for the fluctuating Brownian stresses on the\ncolloids, complementing and related to the traditional fluctuating Brownian\nforces and torques through an extended fluctuation-dissipation theorem based on\nthe hydrodynamic grand resistance matrix. Time-averaging of the fluctuating\nterms gives rise to novel non-fluctuating stresslets. Brownian Dynamics\nsimulations of spheroidal particles illustrate the necessity of these\nfluctuating and non-fluctuating contributions to obtaining consistent\nviscosities."
    },
    {
        "anchor": "Orientational order as the origin of the long-range hydrophobic effect: The long range attractive force between two hydrophobic surfaces immersed in\nwater is observed to decrease exponentially with their separation -- this\ndistance-dependence of effective force is known as the hydrophobic force law\n(HFL). We explore the microscopic origin of HFL by studying distance-dependent\nattraction between two parallel rods immersed in 2D Mercedes Benz model of\nwater. This model is found to exhibit a well-defined HFL. Although the\nphenomenon is conventionally explained by density-dependent theories, we\nidentify orientation, rather than density, as the relevant order parameter. The\nrange of density variation is noticeably shorter than that of orientational\nheterogeneity. The latter is comparable to the observed distances of\nhydrophobic force. At large separation, attraction between the rods arises\nprimarily from a destructive interference among the inwardly propagating\noppositely oriented heterogeneity generated in water by the two rods. As the\nrods are brought closer, the interference increases leading to a decrease in\nheterogeneity and concomitant decrease in free energy of the system, giving\nrise to the effective attraction. We notice formation of hexagonal ice-like\nstructures at the onset of attractive region which suggests that metastable\nfree energy minimum may play a role in the origin of HFL.",
        "positive": "Fundamental challenges in packing problems: from spherical to\n  non-spherical particles: Random packings of objects of a particular shape are ubiquitous in science\nand engineering. However, such jammed matter states have eluded any systematic\ntheoretical treatment due to the strong positional and orientational\ncorrelations involved. In recent years progress on a fundamental description of\njammed matter could be made by starting from a constant volume ensemble in the\nspirit of conventional statistical mechanics. Recent work has shown that this\napproach, first introduced by S. F. Edwards more than two decades ago, can be\ncast into a predictive framework to calculate the packing fractions of both\nspherical and non-spherical particles."
    },
    {
        "anchor": "Defect-mediated morphologies in growing cell colonies: Morphological trends in growing colonies of living cells are at the core of\nphysiological and evolutionary processes. Using active gel equations, which\ninclude cell division, we show that shape changes during the growth can be\nregulated by the dynamics of topological defects in the orientation of cells.\nThe friction between the dividing cells and underlying substrate drives\nanisotropic colony shapes toward more isotropic morphologies, by mediating the\nnumber density and velocity of topological defects. We show that the defects\ninteract with the interface at a specific interaction range, set by the\nvorticity length scale of flows within the colony, and that the cells\npredominantly reorient parallel to the interface due to division-induced active\nstresses.",
        "positive": "Directed polymers at finite temperatures in 1+1 and 2+1 dimensions: We present systematic numerical simulations for directed polymers at finite\ntemperatures in 1+1 and 2+1 dimensions. The transverse fluctuations and free\nenergy fluctuations tend to the strong coupling limit at any temperature in\nboth 1+1 and 2+1 dimensions for long time t. Two different definitions for\nenergy fluctuations at finite temperatures, which are the ensemble energy\nfluctuations and the internal energy fluctuations, are investigated. Apart from\nzero temperature, the behavior of the energy fluctuations and the free energy\nfluctuations for directed polymers is shown to be different. At finite\ntemperatures, the ensemble energy fluctuations in both 1+1 and 2+1 dimensions\nand internal energy fluctuations in 1+1 dimensions scale as t^{1/2} where the\nfree energy fluctuations in 1+1 dimensions and 2+1 dimensions scale as t^{1/3}\nand t^{0.2} respectively. As a consequence of that the specific heat in both\n1+1 and 2+1 dimensions scales as t and the entropy fluctuations in 1+1\ndimensions scale as t^{1/2} at any finite temperature."
    },
    {
        "anchor": "Exact Multifractal Spectra for Arbitrary Laplacian Random Walks: Iterated conformal mappings are used to obtain exact multifractal spectra of\nthe harmonic measure for arbitrary Laplacian random walks in two dimensions.\nSeparate spectra are found to describe scaling of the growth measure in time,\nof the measure near the growth tip, and of the measure away from the growth\ntip. The spectra away from the tip coincide with those of conformally invariant\nequilibrium systems with arbitrary central charge $c\\leq 1$, with $c$ related\nto the particular walk chosen, while the scaling in time and near the tip\ncannot be obtained from the equilibrium properties.",
        "positive": "Structural lubricity and fractures in liquid crystals: Structural superlubricity, one of the most important concepts in modern\ntribology, has attracted lots of interest in both fundamental research and\npractical applications. However, despite promising theoretical models, such as\nthe Prandtl-Tomlinson and Frenkel-Kontorova models, and great success in\nstructural lubricant experiments with two-dimensional materials and colloids,\nthese models have not been directly tested. Here, with the cholesteric liquid\ncrystals confined under the Surface Force Balance, we measure the surface\ntorque during rotational friction, and the molecular rotation from the\ncommensurate to incommensurate configuration, at the onset of structural\nlubricity. Furthermore, by changing the surface potential, the Aubry transition\nis confirmed. The results agree well with the description by a modified\nthree-dimensional version of the above models and provide molecular evidence\nfor rupture nucleation during static friction. Our study bridges the gap\nbetween theories and experiments, and reinforces the connection between\nfriction and fracture."
    },
    {
        "anchor": "Criticality in the approach to failure in amorphous solids: Failure of amorphous solids is fundamental to various phenomena, including\nlandslides and earthquakes. Recent experiments indicate that highly plastic\nregions form elongated structures that are especially apparent near the maximal\nshear stress $\\Sigma_{\\max}$ where failure occurs. This observation suggested\nthat $\\Sigma_{\\max}$ acts as a critical point where the length scale of those\nstructures diverges, possibly causing macroscopic transient shear bands. Here\nwe argue instead that the entire solid phase ($\\Sigma<\\Sigma_{\\max}$) is\ncritical, that plasticity always involves system-spanning events, and that\ntheir magnitude diverges at $\\Sigma_{\\max}$ independently of the presence of\nshear bands. We relate the statistics and fractal properties of these\nrearrangements to an exponent $\\theta$ that captures the stability of the\nmaterial, which is observed to vary continuously with stress, and we confirm\nour predictions in elastoplastic models.",
        "positive": "Nonequilibrium phase behaviour from minimization of free power\n  dissipation: We develop a general theory for describing phase coexistence between\nnonequilibrium steady states in Brownian systems, based on power functional\ntheory (M. Schmidt and J.M. Brader, J. Chem. Phys. 138, 214101 (2013)). We\napply the framework to the special case of fluid-fluid phase separation of\nactive soft sphere swimmers. The central object of the theory, the dissipated\nfree power, is calculated via computer simulations and compared to a simple\nanalytical approximation. The theory describes well the simulation data and\npredicts motility-induced phase separation due to avoidance of dissipative\nclusters."
    },
    {
        "anchor": "Localizing softness and stress along loops in three-dimensional\n  topological metamaterials: Topological states can be used to control the mechanical properties of a\nmaterial along an edge or around a localized defect. The surface rigidity of\nelastic networks is characterized by a bulk topological invariant called the\npolarization; materials with a well-defined uniform polarization display a\ndramatic range of edge softnesses depending on the orientation of the\npolarization relative to the terminating surface. However, in all\nthree-dimensional mechanical metamaterials proposed to date, the topological\nedge modes are mixed with bulk soft modes and so-called Weyl loops. Here, we\nreport the design of a gapped 3D topological metamaterial with a uniform\npolarization that displays a corresponding asymmetry between the number of soft\nmodes on opposing surfaces and, in addition, no bulk soft modes. We then use\nthis construction to localize topological soft modes in interior regions of the\nmaterial by including defect structures---dislocation loops---that are unique\nto three dimensions. We derive a general formula that relates the difference in\nthe number of soft modes and states of self-stress localized along the\ndislocation loop to the handedness of the vector triad formed by the lattice\npolarization, Burgers vector, and dislocation-line direction. Our findings\nsuggest a novel strategy for pre-programming failure and softness localized\nalong lines in 3D, while avoiding extended periodic failure modes associated\nwith Weyl loops.",
        "positive": "Giant thermoelectric response of confined electrolytes with thermally\n  activated charge carrier generation: The thermoelectric response of thermally activated electrolytes (TAE) in a\nslit channel is studied theoretically and by numerical simulations. The term\nTAE refers to electrolytes whose charge carrier concentration is a function of\ntemperature, as recently suggested for ionic liquids and highly concentrated\naqueous electrolyte solutions. Two competing mechanisms driving charge\ntransport by temperature gradients are identified. For suitable values of the\nactivation energy that governs the generation of charge carriers, a giant\nthermoelectric response is found, which could help explaining recent\nexperimental results for nanoporous media infiltrated with TAEs."
    },
    {
        "anchor": "Chemical Potential of a Flexible Polymer Liquid in a Coarse-Grained\n  Representation: While the excess chemical potential is the key quantity in determining phase\ndiagrams, its direct computation for high-density liquids of long polymer\nchains has posed a significant challenge. Computationally, the excess chemical\npotential is calculated using the Widom insertion method, which involves\nmonitoring the change in internal energy as one incrementally introduces\nindividual molecules in the liquid. However, when dealing with dense polymer\nliquids, inserting long chains requires generating trial configurations with a\nbias that favors those at low energy on a unit-by-unit basis: a procedure that\nbecomes more challenging as the number of units increases. Thus, calculating\nthe excess chemical potential of dense polymer liquids using this method\nbecomes computationally intractable as the chain length exceeds $N > 30$. Here,\nwe adopt a coarse-grained model derived from integral equation theory, for\nwhich inserting long polymer chains becomes feasible. The Integral Equation\ntheory of Coarse-Graining (IECG) represents a polymer as a sphere or a\ncollection of blobs interacting through a soft potential. We employ the IECG\napproach to compute the excess chemical potential using Widom's method for\npolymer chains of increasing lengths, extending up to $N=720$ monomers, and at\ndensities reaching up to $\\rho= 0.767$ g/cm$^{3}$. From a fundamental\nperspective, we demonstrate that the excess chemical potentials remain nearly\nconstant across various levels of coarse-graining, offering valuable insights\ninto the consistency of this type of procedure. Ultimately, we argue that\ncurrent Monte Carlo (MC) algorithms, originally designed for atomistic\nsimulations, such as Configurational Bias Monte Carlo (CBMC) methods, can\nsignificantly benefit from the integration of the IECG approach, thereby\nenhancing their performance in the study of phase diagrams of polymer liquids.",
        "positive": "Microfluidic self assembly: Recent progress in colloidal science has led to elaborate self-assembled\nstructures whose complexity raises hopes for elaborating new materials.\nHowever, the throughputs are extremely low and consequently, the chance to\nproduce materials of industrial interest, for instance, groundbreaking optical\ndevices, harnessing complete three-dimensional band gaps, is markedly low.\n  We discovered a novel hydrodynamic effect that may unlock this bottleneck. It\nis based on the dipolar flow interactions that build up when droplets are\nslowed down by the microchannel walls along which they are transported. Coupled\nwith depletion forces, we succeeded to form, via a continuous flow process, at\nunprecedented speeds and under exquisite control, a rich ensemble of\nmonodisperse planar and tridimensional clusters, such as chains, triangles,\ndiamonds, tetahedrons, heterotrimers, possessing geometrical, chemical, and/or\nmagnetic anisotropies enabling directional bonding. Continuous productions of\nmillions of building blocks per second for elaborating new functional materials\ncan be envisioned."
    },
    {
        "anchor": "Stochastic kinetics reveal imperative role of anisotropic interfacial\n  tension to determine morphology and evolution of nucleated droplets in\n  nematogenic films: For isotropic fluids, classical nucleation theory predicts the nucleation\nrate, barrier height and critical droplet size by accounting for the\ncompetition between bulk energy and interfacial tension. The nucleation process\nin liquid crystals is less understood. We numerically investigate nucleation in\nmonolayered nematogenic films using a mesoscopic framework, in particular, we\nstudy the mor- phology and kinetic pathway in spontaneous formation and growth\nof droplets of the stable phase in the metastable background. The parameter\n$\\kappa$ that quantifies the anisotropic elastic energy plays a central role in\ndetermining the geometric structure of the droplets. Noncircular nematic\ndroplets with homogeneous director orientation are nucleated in a background of\nsupercooled isotropic phase for small $\\kappa$. For large $\\kappa$, noncircular\ndroplets with integer topological charge, accompanied by a biaxial ring at the\nouter surface, are nucleated. The isotropic droplet shape in a superheated\nnematic background is found to depend on $\\kappa$ in a similar way. Identical\ngrowth laws are found in the two cases, although an unusual two-stage mechanism\nis observed in the nucleation of isotropic droplets. Temporal distributions of\nsuccessive events indicate the relevance of long-ranged elasticity-mediated\ninteractions within the isotropic domains. Implications for a theoretical\ndescription of nucleation in anisotropic fluids are discussed.",
        "positive": "Juggling bubbles in square capillaries: an experimental proof of\n  non-pairwise bubble interactions: .The physical properties of an ensemble of tightly packed particles like\nbubbles, drops or solid grains are controlled by their interactions. For the\ncase of bubbles and drops it has recently been shown theoretically and\ncomputationally that their interactions cannot generally be represented by\npair-wise additive potentials, as is commonly done for simulations of soft\ngrain packings. This has important consequences for the mechanical properties\nof foams and emulsions, especially for strongly deformed bubbles or droplets\nwell above the jamming point. Here we provide the first experimental\nconfirmation of this prediction by quantifying the interactions between bubbles\nin simple model foams consisting of trains of equal-volume bubbles confined in\nsquare capillaries. The obtained interaction laws agree quantitatively with\nSurface Evolver simulations and are well described by an analytically derived\nexpression based on the recently developed non-pairwise interaction model of\nH\\\"ohler et al. [Soft Matter, 2017, 13,(7):1371], based on Morse-Witten theory.\nWhile all experiments are done at Bond numbers sufficiently low for the\nhydrostatic pressure variation across one bubble to be negligible, we provide\nthe full analysis taking into account gravity in the appendix for the\ninterested reader. Even though the article focuses on foams, all results\ndirectly apply to the case of emulsions."
    },
    {
        "anchor": "Incorporating Ion-Specific van der Waals and Soft Repulsive Interactions\n  in the Poisson-Boltzmann Theory of Electrical Double Layers: Electrical double layers (EDLs) arise when an electrolyte is in contact with\na charged surface, and are encountered in several application areas including\nbatteries, supercapacitors, electrocatalytic reactors, and colloids. In the\nmodeling of EDLs, a prominent knowledge gap has been the exclusion of van der\nWaals (vdW) and soft repulsive interactions in modified Poisson-Boltzmann (PB)\ntheories. Although more short-ranged as compared to electrostatic interactions,\nwe show here that vdW interactions can play an important role in determining\nthe structure of the EDL via the formation of a Stern layer and in modulating\nthe differential capacitance of an electrode in solution. To this end, we\nincorporate ion-ion and wall-ion vdW attraction and soft repulsion via a 12-6\nLennard-Jones (LJ) potential, resulting in a modified PB-LJ approach. The\nwall-ion LJ interactions were found to have a significant effect on the\nelectrical potential and concentration profiles, especially close to the wall.\nHowever, ion-ion LJ interactions do not affect the EDL structure at low bulk\nion concentrations (< 1 M). We also derive dimensionless numbers to quantify\nthe impact of ion-ion and wall-ion LJ interactions on the EDL. Furthermore, in\nthe pursuit of capturing ion-specific effects, we apply our model by\nconsidering various combinations of ions. We observe how varying parameters\nsuch as the electrolyte concentration and electrode potential affect the\nstructure of the EDL due to the competition between ion-specific LJ and\nelectrostatic interactions. Lastly, we show that the inclusion of vdW and soft\nrepulsion interactions as well as hydration effects lead to a better\nqualitative agreement of the PB models with experimental double-layer\ndifferential capacitance data. Overall, the modified PB-LJ approach presented\nherein will lead to more accurate theoretical descriptions of EDLs in various\napplication areas.",
        "positive": "Role of particle aggregation on the structure of dried colloidal silica\n  layers: The process of colloidal drying gives way to particle self-assembly in\nnumerous elds including photonics or biotechnology. Yet, the mechanisms and\nconditions driving the nal particle arrangement in dry colloidal layers remain\nelusive. Here, we examine how the drying rate selects the nanostructure of\nthick dried layers in four dierent suspensions of silica nanospheres. Depending\non particle size and dispersity, either an amorphous arrangement, a crystalline\narrangement, or a rate-dependent amorphous-to-crystalline transition occurs at\nthe drying surface. Amorphous arrangements are observed in the two most\npolydisperse suspensions while crystallinity occurs when dispersity is lower.\nCounter-intuitively in the latter case, a higher drying rate favors ordering of\nthe particles. To complement these measurements and to take stock of the bulk\nproperties of the layer, tests on the layer porosity were undertaken. For all\nsuspensions studied herein, faster drying yields denser dry layers. Crystalline\nsurface arrangement implies large bulk volume fraction ($\\sim$ 0.65) whereas\namorphous arrangements can be observed in layers with either low (down to\n$\\sim$ 0.53) or high ($\\sim$ 0.65) volume fraction. Lastly, we demonstrate via\ntargeted additional experiments and SAXS measurements, that the packing\nstructure of the layers is mainly driven by the formation of aggregates and\ntheir subsequent packing, and not by the competition between Brownian diusion\nand convection. This highlights that a second dimensionless ratio in addition\nto the Peclet number should be taken into account, namely the aggregation over\nevaporation timescale."
    },
    {
        "anchor": "Scaling of the elastic contribution to the surface free energy of a\n  nematic on a sawtoothed substrate: We characterize the elastic contribution to the surface free energy of a\nnematic in presence of a sawtooth substrate. Our findings are based on\nnumerical minimization of the Landau-de Gennes model and analytical\ncalculations on the Frank-Oseen theory. The nucleation of disclination lines\n(characterized by non-half-integer winding numbers) in the wedges and apexes of\nthe substrate induces a leading order proportional to qlnq to the elastic\ncontribution to the surface free energy density, q being the wavenumber\nassociated with the substrate periodicity.",
        "positive": "Machine learning that predicts well may not learn the correct physical\n  descriptions of glassy systems: The complexity of glasses makes it challenging to explain their dynamics.\nMachine Learning (ML) has emerged as a promising pathway for understanding\nglassy dynamics by linking their structural features to rearrangement dynamics.\nSupport Vector Machine (SVM) was one of the first methods used to detect such\ncorrelations. Specifically, a certain output of SVMs trained to predict\ndynamics from structure, the distance from the separating hyperplane, was\ninterpreted as being linearly related to the activation energy for the\nrearrangement. By numerical analysis of toy models, we explore under which\nconditions it is possible to infer the energy barrier to rearrangements from\nthe distance to the separating hyperplane. We observe that such successful\ninference is possible only under very restricted conditions. Typical tests,\nsuch as the apparent Arrhenius dependence of the probability of rearrangement\non the inferred energy and the temperature, or high cross-validation accuracy\ndo not guarantee success. We propose practical approaches for measuring the\nquality of the energy inference and for modifying the inferred model to improve\nthe inference, which should be usable in the context of realistic datasets."
    },
    {
        "anchor": "An integrated DEM-FEM approach to study breakage in packing of glass\n  cartridges on a conveyor belt: The use of glass for pharmaceutical new applications such as high-technology\ndrugs, requires the strictest container inertness. A common theme of paramount\nimportance in glass container integrity preservation is the detailed mechanism\ndriving the sudden failure due the crack propagation. Using a combination of\nDiscrete Element Method (DEM) and Finite Element Method (FEM), a stress map for\nglass cartridges packed into an accumulation table and transported by a\nconveyor belt at a fixed velocity is obtained under realistic conditions. The\nDEM calculation provides a full description of the dynamics of the cartridges,\nas approximated by an equivalent sphere, as well as the statistics of the\nmultiple collisions. The FEM calculation exploits this input to provide the\nmaximum principal stress of different pairs as a function of time. Our analysis\nshows that, during their transportation on the conveyor belt, the cartridges\nare subject to several shocks of varying intensities. Under these conditions, a\ncrack may originate inside the cartridge in the area of maximal tensile stress,\nand propagate outward. Estimated stresses are found in good agreement with real\nsystems.",
        "positive": "Kosmotropic effect leads to LCST decrease in thermoresponsive polymer\n  solutions: We study the phenomena of decrease in lower critical solution temperature\n(LCST) with addition of kosmotropic (order-making) cosolvents in\nthermoresponsive polymer solutions. A combination of explicit solvent\ncoarse-grained simulations and mean-field theory has been employed. The\npolymer-solvent LCST behavior in the theoretical models have been incorporated\nthrough the Kolomeisky-Widom solvophobic potential. Our results illustrate how\nthe decrease in the LCST can be achieved by the reduction in the bulk solvent\nenergy with addition of cosolvent. It is shown that this effect of cosolvent is\nweaker with increase in polymer hydrophilicity which can explain the absence of\nLCST decrease in PDEA, water and methanol systems. The coarse-grained nature of\nthe models indicates that a mean energetic representation of the system is\nsufficient to understand the phenomena of LCST decrease."
    },
    {
        "anchor": "Collective rotational motion of freely-expanding T84 epithelial cell\n  colonies: Coordinated rotational motion is an intriguing, yet still elusive mode of\ncollective cell migration, which is relevant in pathological and morphogenetic\nprocesses. Most of the studies on this topic have been carried out on confined\nepithelial cells. The driver of collective rotation in such conditions has not\nbeen clearly elucidated, although it has been speculated that spatial\nconfinement can play an essential role in triggering cell rotation. Here, we\nstudy the growth of epithelial cell colonies freely expanding (i.e., with no\nphysical constraints) on the surface of cell culture plates, a case which has\nreceived scarce attention in the literature. We find that coordinated cell\nrotation spontaneously occurs in cell clusters in the free growth regime, thus\nimplying that cell confinement is not necessary to elicit collective rotation\nas previously suggested. The collective rotation was size and shape dependent:\na highly coordinated disk-like rotation was found in small cell clusters with a\nround shape, while collective rotation was suppressed in large irregular cell\nclusters generated by merging of different clusters in the course of their\ngrowth. The angular motion was persistent in the same direction, although\nclockwise and anticlockwise rotations were equally likely to occur among\ndifferent cell clusters. Radial cell velocity was low as compared to the\nangular velocity. A clear difference in morphology was observed between cells\nat the periphery and the ones in the core of the clusters, the former being\nmore elongated and spread out as compared to the latter. Overall, our results\nprovide the first quantitative and systematic evidence that coordinated cell\nrotation does not require a spatial confinement and occurs spontaneously in\nfreely expanding epithelial cell colonies.",
        "positive": "Formation of polyhedral vesicles and polygonal membrane tubes induced by\n  banana-shaped proteins: The shape transformations of fluid membranes induced by curved protein rods\nare studied using meshless membrane simulations. The rod assembly at low rod\ndensity induces a flat membrane tube and oblate vesicle. It is found that the\npolyhedral shapes are stabilized at high rod densities. The discrete shape\ntransition between triangular and buckled discoidal tubes is obtained and their\ncurvature energies are analyzed by a simple geometric model. For vesicles,\ntriangular hosohedron and elliptic-disk shapes are formed in equilibrium,\nwhereas tetrahedral and triangular prism shapes are obtained as metastable\nstates."
    },
    {
        "anchor": "Foam as a self-assembling amorphous photonic band gap material: We show that slightly polydisperse disordered 2D foams can be used as a\nself-assembled template for isotropic photonic band gap (PBG) materials for\ntransverse electric (TE) polarization. Calculations based on in-house\nexperimental and simulated foam structures demonstrate that, at sufficient\nrefractive index contrast, a dry foam organization with threefold nodes and\nlong slender Plateau borders is especially advantageous to open a large PBG. A\ntransition from dry to wet foam structure rapidly closes the PBG mainly by\nformation of bigger fourfold nodes, filling the PBG with defect modes. By\ntuning the foam area fraction, we find an optimal quantity of dielectric\nmaterial, which maximizes the PBG in experimental systems. The obtained results\nhave a potential to be extended to 3D foams to produce a next generation of\nself-assembled disordered PBG materials, enabling fabrication of cheap and\nscalable photonic devices.",
        "positive": "Importance of molecular interactions in colloidal dispersions: We review briefly the concept of colloidal dispersions, their general\nproperties and some of their most important applications, as well as the basic\nmolecular interactions that give rise to their properties in equilibrium.\nSimilarly, we revisit Brownian motion and hydrodynamic interactions associated\nwith the concept of viscosity of colloidal dispersion. It is argued that the\nuse of modern research tools, such as computer simulations, allows one to\npredict accurately some macroscopically measurable properties by solving\nrelatively simple models of molecular interactions for a large number of\nparticles. Lastly, as a case study, we report the prediction of rheological\nproperties of polymer brushes using state of the art, coarse grained computer\nsimulations, which are in excellent agreement with experiments."
    },
    {
        "anchor": "Fluctuations and Elastic Properties of Lipid Membranes in the Tilted Gel\n  State: A Coarse-Grained Monte Carlo Study: We study the stress distribution profiles and the height and thickness\nfluctuations of lipid membranes in the tilted gel state by Monte Carlo\nsimulations of a generic coarse-grained model for lipid membranes, which\nreproduces many known properties of DPPC bilayers. The results are related to\nthe corresponding properties of fluid membranes, and to theoretical predictions\nfor crystalline and hexatic membranes. One striking observation is that the\nspontaneous curvature of the monolayers changes sign from the fluid to the gel\nphase. In the gel phase, the long-wavelength height fluctuations are\nsuppressed, and the fluctuation spectrum is highly anisotropic. In the\ndirection of tilt, it carries the signature of soft modes that are compatible\nwith the wavelength of the ripple phase, which emerges in the transition region\nbetween the fluid and the gel state. In the direction perpendicular to the\ntilt, the thickness fluctuations are almost entirely suppressed, and the height\nfluctuations seem to be dominated by an interfacial energy, i.e., by\nout-of-layer fluctuations, up to length scales of tens of nanometers.",
        "positive": "Note: Sound velocities of generalized Lennard-Jones ($n-6$) fluids near\n  freezing: In a recent paper [S. Khrapak, Molecules {\\bf 25}, 3498 (2000)] the\nlongitudinal and transverse sound velocities of conventional Lennard-Jones\nsystems at the liquid-solid coexistence were calculated. It was shown that the\nsound velocities remain almost invariant along the liquid-solid coexistence\nboundary lines and that their magnitudes are comparable with those of repulsive\nsoft sphere and hard sphere models at the fluid-solid phase transition. This\nimplies that attraction does not affect the magnitude of sound velocities at\nthe fluid-solid phase transition. This paper provides further evidence to this\nby examining the generalized Lennard-Jones $n$-6 fluids with $n$ ranging from\n$12$ to $7$ and demonstrating that the steepness of repulsive term has only a\nminor effect on the magnitude of the sound velocities."
    },
    {
        "anchor": "Rotation shields chaotic mixing regions from no-slip walls: We report on the decay of a passive scalar in chaotic mixing protocols where\nthe wall of the vessel is rotated, or a net drift of fluid elements near the\nwall is induced at each period. As a result the fluid domain is divided into a\ncentral isolated chaotic region and a peripheral regular region. Scalar\npatterns obtained in experiments and simulations converge to a strange\neigenmode and follow an exponential decay. This contrasts with previous\nexperiments [Gouillart et al., Phys. Rev. Lett. 99, 114501 (2007)] with a\nchaotic region spanning the whole domain, where fixed walls constrained mixing\nto follow a slower algebraic decay. Using a linear analysis of the flow close\nto the wall, as well as numerical simulations of Lagrangian trajectories, we\nstudy the influence of the rotation velocity of the wall on the size of the\nchaotic region, the approach to its bounding separatrix, and the decay rate of\nthe scalar.",
        "positive": "Critical Casimir force in $^4$He films: confirmation of finite-size\n  scaling: We present new capacitance measurements of critical Casimir force-induced\nthinning of $^4$He films near the superfluid/normal transition, focused on the\nregion below $T_{\\lambda}$ where the effect is the greatest. $^4$He films of\n238, 285, and 340 \\AA thickness are adsorbed on N-doped silicon substrates with\nroughness $\\approx 8 {\\AA}$. The Casimir force scaling function $\\vartheta $,\ndeduced from the thinning of these three films, collapses onto a single\nuniversal curve, attaining a minimum $\\vartheta = -1.30 \\pm 0.03$ at\n$x=td^{1/\\nu}=-9.7\\pm 0.8 {\\AA}^{1/\\nu}$. The collapse confirms the finite-size\nscaling origin of the dip in the film thickness. Separately, we also confirm\nthe presence down to $2.13 K$ of the Goldstone/surface fluctuation force, which\nmakes the superfluid film $\\sim 2 {\\AA}$ thinner than the normal film."
    },
    {
        "anchor": "Generic Maximum-Valence Model for Fluid Polyamorphism: Recently, maximal valence model has been proposed to model liquid-liquid\nphase transition induced by polymerization in sulfur. In this paper we present\na simple generic model to describe liquid polyamorphism in single-component\nfluids using a maximum-valence approach for any arbitrary coordination number.\nThe model contains three types of interactions: i) atoms attract each other by\nvan der Waals forces that generate a liquid-gas transition at low pressures,\nii) atoms may form covalent bonds that induce association, and iii) additional\nrepulsive forces between atoms with maximal valence and atoms with any valence.\nThis additional repulsion generates liquid-liquid phase separation and the\nregion of negative heat expansion coefficient (density anomaly) on a P-T phase\ndiagram. We show the existence of liquid-liquid phase transitions for\ndimerization, polymerization, gelation and network formation for corresponding\ncoordination numbers z = 1, 2, ..6 and discuss the limits of this generic model\nfor producing fluid polyamorphism.",
        "positive": "Short-time inertial response of viscoelastic fluids measured with\n  Brownian motion and with active probes: We have directly observed short-time stress propagation in viscoelastic\nfluids using two optically trapped particles and a fast interferometric\nparticle-tracking technique. We have done this both by recording correlations\nin the thermal motion of the particles and by measuring the response of one\nparticle to the actively oscillated second particle. Both methods detect the\nvortex-like flow patterns associated with stress propagation in fluids. This\ninertial vortex flow propagates diffusively for simple liquids, while for\nviscoelastic solutions the pattern spreads super-diffusively, dependent on the\nshear modulus of the medium."
    },
    {
        "anchor": "Size and shape control of magnetite nanoparticles with a nonselective\n  binding surfactants: A Martian meteorite, magnetic inks, drug targeting, batteries, contrasts for\nMRI, data storage or even clinical thermo-therapy seem to have no connection,\nbut all have in common a dark mineral called magnetite. However, in each of\nthese applications this iron oxide shows up with different forms because their\noptical, electrical and magnetic properties are strongly dependent on size,\nshape and kind of surfactant. In this sense the control of this characteristics\nhas long been of scientific and technological interest. In an AC magnetic\nfield-assisted cancer therapy, \\textit{e.g.}, from a biological point of view,\nthe interaction of the nanoparticles with cells is critically determined by the\nsurface properties which control their fate in biological environments. Besides\nthe size, factors as the shape also seems to affect the cellular uptake. On the\nother hand, the specific absorption rate (SAR) at a fixed frequency and\nmagnetic field, is hugely dependent on average and distribution of size, shape,\ncrystalline anisotropy, and degree of aggregation or agglomeration of the\nnanoparticles. Each of these factors contributes to an independent energy loss\nmechanism: N\\'eel relaxation, Brown relaxation or magnetic hysteresis loss.\nThus, the key for improving the efficiency of a given application is the\nknowledge about the morphological control.",
        "positive": "Surface anchoring as a control parameter for stabilizing torons,\n  skyrmions, twisted walls, fingers and their hybrids in chiral nematics: Chiral condensed matter systems, such as liquid crystals and magnets, exhibit\na host of spatially localized topological structures that emerge from the\nmedium's tendency to twist and its competition with confinement and field\ncoupling effects. We show that the strength of perpendicular surface boundary\nconditions can be used to control the structure and topology of solitonic and\nother localized field configurations. By combining numerical modeling and\nthree-dimensional imaging of the director field, we reveal structural stability\ndiagrams and inter-transformation of twisted walls and fingers, torons and\nskyrmions and their crystalline organizations upon changing boundary\nconditions. Our findings provide a recipe for controllably realizing skyrmions,\ntorons and hybrid solitonic structures possessing features of both of them,\nwhich will aid in fundamental explorations and technological uses of such\ntopological solitons. Moreover, we discuss how other material parameters can be\nused to determine soliton stability, and how similar principles can be\nsystematically applied to other liquid crystal solitons, and solitons in other\nmaterial systems."
    },
    {
        "anchor": "Phase behavior of colloidal suspensions with critical solvents in terms\n  of effective interactions: We study the phase behavior of colloidal suspensions the solvents of which\nare considered to be binary liquid mixtures undergoing phase segregation. We\nfocus on the thermodynamic region close to the critical point of the\naccompanying miscibility gap. There, due to the colloidal particles acting as\ncavities in the critical medium, the spatial confinements of the critical\nfluctuations of the corresponding order parameter result in the effective,\nso-called critical Casimir forces between the colloids. Employing an approach\nin terms of effective, one-component colloidal systems, we explore the\npossibility of phase coexistence between two phases of colloidal suspensions,\none being rich and the other being poor in colloidal particles. The reliability\nof this effective approach is discussed.",
        "positive": "Designing Machine Learning Surrogates using Outputs of Molecular\n  Dynamics Simulations as Soft Labels: Molecular dynamics simulations are powerful tools to extract the microscopic\nmechanisms characterizing the properties of soft materials. We recently\nintroduced machine learning surrogates for molecular dynamics simulations of\nsoft materials and demonstrated that artificial neural network based regression\nmodels can successfully predict the relationships between the input material\nattributes and the simulation outputs. Here, we show that statistical\nuncertainties associated with the outputs of molecular dynamics simulations can\nbe utilized to train artificial neural networks and design machine learning\nsurrogates with higher accuracy and generalizability. We design soft labels for\nthe simulation outputs by incorporating the uncertainties in the estimated\naverage output quantities, and introduce a modified loss function that\nleverages these soft labels during training to significantly reduce the\nsurrogate prediction error for input systems in the unseen test data. The\napproach is illustrated with the design of a surrogate for molecular dynamics\nsimulations of confined electrolytes to predict the complex relationship\nbetween the input electrolyte attributes and the output ionic structure. The\nsurrogate predictions for the ionic density profiles show excellent agreement\nwith the ground truth results produced using molecular dynamics simulations.\nThe high accuracy and small inference times associated with the surrogate\npredictions provide quick access to quantities derived using the number density\nprofiles and facilitate rapid sensitivity analysis."
    },
    {
        "anchor": "Capillary stress and structural relaxation in moist granular materials: We propose a theoretical framework to calculate capillary stresses in complex\nmesoporous materials, such as moist sand, nanoporous hydrates, and drying\ncolloidal films. Molecular simulations are mapped onto a phase-field model of\nthe liquid-vapor mixture, whose inhomogeneous stress tensor is integrated over\nVoronoi polyhedra in order to calculate equal and opposite forces between each\npair of neighboring grains. The method is illustrated by simulations of\nmoisture-induced forces in small clusters and random packings of spherical\ngrains using lattice-gas Density Functional Theory. For a nano-granular model\nof cement hydrates, this approach reproduces the hysteretic water\nsorption/desorption isotherms and predicts drying shrinkage strain isotherm in\ngood agreement with experiments. We show that capillary stress is an effective\nmechanism for internal stress relaxation in colloidal random packings, which\ncontributes to the extraordinary durability of cement paste.",
        "positive": "Scale-free static and dynamical correlations in melts of monodisperse\n  and Flory-distributed homopolymers: A review of recent bond-fluctuation model\n  studies: It has been assumed until very recently that all long-range correlations are\nscreened in three-dimensional melts of linear homopolymers on distances beyond\nthe correlation length $\\xi$ characterizing the decay of the density\nfluctuations. Summarizing simulation results obtained by means of a variant of\nthe bond-fluctuation model with finite monomer excluded volume interactions and\ntopology violating local and global Monte Carlo moves, we show that due to an\ninterplay of the chain connectivity and the incompressibility constraint, both\nstatic and dynamical correlations arise on distances $r \\gg \\xi$. These\ncorrelations are scale-free and, surprisingly, do not depend explicitly on the\ncompressibility of the solution. Both monodisperse and (essentially)\nFlory-distributed equilibrium polymers are considered."
    },
    {
        "anchor": "Monte Carlo Protein Folding: Simulations of Met-Enkephalin with\n  Solvent-Accessible Area Parameterizations: Treating realistically the ambient water is one of the main difficulties in\napplying Monte Carlo methods to protein folding. The solvent-accessible area\nmethod, a popular method for treating water implicitly, is investigated by\nmeans of Metropolis simulations of the brain peptide Met-Enkephalin. For the\nphenomenological energy function ECEPP/2 nine atomic solvation parameter (ASP)\nsets are studied that had been proposed by previous authors. The simulations\nare compared with each other, with simulations with a distance dependent\nelectrostatic permittivity $\\epsilon (r)$, and with vacuum simulations\n($\\epsilon =2$). Parallel tempering and a recently proposed biased Metropolis\ntechnique are employed and their performances are evaluated. The measured\nobservables include energy and dihedral probability densities (pds), integrated\nautocorrelation times, and acceptance rates. Two of the ASP sets turn out to be\nunsuitable for these simulations. For all other sets, selected configurations\nare minimized in search of the global energy minima. Unique minima are found\nfor the vacuum and the $\\epsilon(r)$ system, but for none of the ASP models.\nOther observables show a remarkable dependence on the ASPs. In particular,\nautocorrelation times vary dramatically with the ASP parameters. Three ASP sets\nhave much smaller autocorrelations at 300 K than the vacuum simulations,\nopening the possibility that simulations can be speeded up vastly by\njudiciously chosing details of the force",
        "positive": "Three-dimensional Brownian diffusion of rod-like macromolecules in the\n  presence of randomly distributed spherical obstacles: Molecular dynamics\n  simulation: Brownian diffusion of rod-like polymers in the presence of randomly\ndistributed spherical obstacles is studied using molecular dynamics (MD)\nsimulations. It is observed that dependence of the reduced diffusion\ncoefficient of these macromolecules on the available volume fraction can be\ndescribed reasonably by a power law function. Despite the case of obstructed\ndiffusion of flexible polymers in which reduced diffusion coefficient has a\nweak dependence on the polymer length, this dependence is noticeably strong in\nthe case of rod-like polymers. Diffusion of these macromolecules in the\npresence of obstacles is observed that is anomalous at short time scales and\nnormal at long times. Duration time of the anomalous diffusion regime is found\nthat increases very rapidly with increasing both the polymer length and the\nobstructed volume fraction. Dynamics of diffusion of these polymers is observed\nthat crosses over from Rouse to reptation type with increasing the density of\nobstacles."
    },
    {
        "anchor": "Swinging and tumbling of elastic capsules in shear flow: The deformation of an elastic micro-capsule in an infinite shear flow is\nstudied numerically using a spectral method. The shape of the capsule and the\nhydrodynamic flow field are expanded into smooth basis functions. Analytic\nexpressions for the derivative of the basis functions permit the evaluation of\nelastic and hydrodynamic stresses and bending forces at specified grid points\nin the membrane. Compared to methods employing a triangulation scheme, this\nmethod has the advantage that the resulting capsule shapes are automatically\nsmooth, and few modes are needed to describe the deformation accurately.\nComputations are performed for capsules both with spherical and ellipsoidal\nunstressed reference shape. Results for small deformations of initially\nspherical capsules coincide with analytic predictions. For initially\nellipsoidal capsules, recent approximative theories predict stable oscillations\nof the tank-treading inclination angle, and a transition to tumbling at low\nshear rate. Both phenomena have also been observed experimentally. Using our\nnumerical approach we could reproduce both the oscillations and the transition\nto tumbling. The full phase diagram for varying shear rate and viscosity ratio\nis explored. While the numerically obtained phase diagram qualitatively agrees\nwith the theory, intermittent behaviour could not be observed within our\nsimulation time. Our results suggest that initial tumbling motion is only\ntransient in this region of the phase diagram.",
        "positive": "Quasi-periodic vs. irreversible dynamics of an optically confined\n  Bose-Einstein condensate: We consider the evolution of a dilute Bose-Einstein condensate in an optical\ntrap formed by a doughnut laser mode. By solving a one dimensional\nGross-Pitaevskii equation and looking at the variance and the statistical\nentropy associated with the position of the system we can study the dynamical\nbehavior of the system. It is shown that for small condensates nonlinear\nrevivals of the macroscopic wave function are expected. For sufficiently large\nand dense condensates irreversible dynamics takes place for which revivals of\nregular dynamics appear as predicted in [9]. These results are confirmed by a\ntwo dimensional simulation in which the scales of energy associated with the\ntwo different directions mimic the experimental situation."
    },
    {
        "anchor": "Geometry of membranes: This review reports some theoretical results on the Geometry of membranes.\nThe governing equations to describe equilibrium configurations of lipid\nvesicles, lipid membranes with free edges, and chiral lipid membranes are\nderived from the variation of free energies of these structures. Some analytic\nsolutions to these equations and their corresponding configurations are also\nshown.",
        "positive": "Heterogeneous critical nucleation on a completely-wettable substrate: Heterogeneous nucleation of a new bulk phase on a flat substrate can be\nassociated with the surface phase transition called wetting transition. When\nthis bulk heterogeneous nucleation occurs on a completely-wettable flat\nsubstrate with a zero contact angle, the classical nucleation theory predicts\nthat the free energy barrier of nucleation vanishes. In fact, there always\nexist a critical nucleus and a free energy barrier as the first-order\npre-wetting transition will occur even when the contact angle is zero.\nFurthermore, the critical nucleus changes its character from the critical\nnucleus of surface phase transition below bulk coexistence (undersaturation) to\nthe critical nucleus of bulk heterogeneous nucleation above the coexistence\n(oversaturation) when it crosses the coexistence. Recently, Sear [J.Chem.Phys\n{\\bf 129}, 164510 (2008)] has shown by a direct numerical calculation of\nnucleation rate that the nucleus does not notice this change when it crosses\nthe coexistence. In our work the morphology and the work of formation of\ncritical nucleus on a completely-wettable substrate are re-examined across the\ncoexistence using the interface-displacement model. Indeed, the morphology and\nthe work of formation changes continuously at the coexistence. Our results\nsupport the prediction of Sear and will rekindle the interest on heterogeneous\nnucleation on a completely-wettable substrate."
    },
    {
        "anchor": "Da Vinci Fluids, catch-up dynamics and dense granular flow: We introduce and study a da Vinci Fluid, a fluid whose dissipation is\ndominated by solid friction. We analyse the flow rheology of a discrete model\nand then coarse-grain it to the continuum. We find that the model gives rise to\nbehaviour that is characteristic of dense granular fluids. In particular, it\nleads to plug flow. We analyse the nucleation mechanism of plugs and their\ndevelopment. We find that plug boundaries generically expand and we calculate\nthe growth rate of plug regions. In systems whose internal effective friction\ncoefficient is relatively uniform we find that the linear size of plug regions\ngrows as (time)$^{1/3}$. The suitability of the model to granular materials is\ndiscussed.",
        "positive": "Orientational ordering of point dipoles on a sphere: Arrangement of interacting particles on a sphere is historically a well known\nproblem, however, ordering of particles with anisotropic interaction, such as\nthe dipole-dipole interaction, has remained unexplored. We solve the\norientational ordering of point dipoles on a sphere with fixed positional order\nwith numerical minimization of interaction energy and analyze stable\nconfigurations depending on their symmetry and degree of ordering. We find that\na macrovortex is a generic ground state, with various discrete rotational\nsymmetries for different system sizes, while higher energy metastable states\nare similar, but less ordered. We observe orientational phase transitions and\nhysteresis in response to changing external field both for the fixed sphere\norientation with respect the field, as well as for a freely-rotating sphere.\nFor the case of a freely rotating sphere, we also observe changes of the\nsymmetry axis with increasing field strength."
    },
    {
        "anchor": "Theory and simulation studies of self-assembly of helical particle: This is the unedited authors' version of Chapter 3 appearing in the following\nbook: Self-Assembly Systems: Theory and Simulations Ed. Li-Tang Yan John Wiley\n& Sons, Ltd, Chichester, pp. 53-84 (2017)",
        "positive": "Derivation of the Johnson-Samwer $T^{(2/3)}$ Temperature Dependence of\n  the Yield Strain in Metallic Glasses: Metallic Glasses are prone to fail mechanically via a shear-banding\ninstability. In a remarkable paper Johnson and Samwer demonstrated that this\nfailure enjoys a high degree of universality in the sense that a large group of\nmetallic glasses appears to possess a yield-strain that decreases with\ntemperature following a $-T^{2/3}$ law up to logarithmic corrections. In this\nLetter we offer a theoretical derivation of this law. We show that our formula\nfits very well simulational data on typical amorphous solids."
    },
    {
        "anchor": "Computational models for active matter: A variety of computational models have been developed to describe active\nmatter at different length and time scales. The diversity of the methods and\nthe challenges in modeling active matter---ranging from molecular motors and\ncytoskeletal filaments over artificial and biological swimmers on microscopic\nto groups of animals on macroscopic scales---mainly originate from their\nout-of-equilibrium character, multiscale nature, nonlinearity, and multibody\ninteractions. In the present review, various modeling approaches and numerical\ntechniques are addressed, compared, and differentiated to illuminate the\ninnovations and current challenges in understanding active matter. The\ncomplexity increases from minimal microscopic models of dry active matter\ntoward microscopic models of active matter in fluids. Complementary,\ncoarse-grained descriptions and continuum models are elucidated. Microscopic\ndetails are often relevant and strongly affect collective behaviors, which\nimplies that the selection of a proper level of modeling is a delicate choice,\nwith simple models emphasizing universal properties and detailed models\ncapturing specific features. Finally, current approaches to further advance the\nexisting models and techniques to cope with real-world applications, such as\ncomplex media and biological environments, are discussed.",
        "positive": "Penrose Tilings as Jammed Solids: Penrose tilings form lattices, exhibiting 5-fold symmetry and isotropic\nelasticity, with inhomogeneous coordination much like that of the force\nnetworks in jammed systems. Under periodic boundary conditions, their average\ncoordination is exactly four. We study the elastic and vibrational properties\nof rational approximants to these lattices as a function of unit-cell size\n$N_S$ and find that they have of order $\\sqrt{N_S}$ zero modes and states of\nself stress and yet all their elastic moduli vanish. In their generic form\nobtained by randomizing site positions, their elastic and vibrational\nproperties are similar to those of particulate systems at jamming with a\nnonzero bulk modulus, vanishing shear modulus, and a flat density of states."
    },
    {
        "anchor": "Circumferential buckling of a hydrogel tube emptying upon dehydration: A cylindrical hydrogel tube, completely submerged in water, hydrates by\nswelling and filling its internal cavity. When it comes back into contact with\nair, it dehydrates: the tube thus expels the solvent through the walls,\nshrinking. This dehydration process causes a depression in the tube cavity,\nwhich can lead to circumferential buckling. Here we study the occurrence of\nsuch buckling using a continuous model that combines non-linear elasticity with\nFlory-Rehner theory, to take into account both the large deformations and the\nactive behavior of the hydrogel. In quasi-static approximation, we use the\nincremental deformation formalism, extended to the chemo-mechanical equations,\nto determine the threshold value of the enclosed volume at which buckling is\ntriggered. This critical value is found to depend on the shell thickness,\nchemical potential and constitutive features. The results obtained are in good\nagreement with the results of the finite element simulations of the complete\ndynamic problem.",
        "positive": "Multiple Glasses in Asymmetric Binary Hard Spheres: Multiple distinct glass states occur in binary hard-sphere mixtures with\nconstituents of very disparate sizes according to the mode-coupling theory of\nthe glass transition (MCT), distinguished by considering whether small\nparticles remain mobile or not, and whether small particles contribute\nsignificantly to perturb the big-particle structure or not. In the idealized\nglass, the four different glasses are separated by sharp transitions that give\nrise to higher-order transition phenomena involving logarithmic decay laws, and\nto anomalous power-law-like diffusion. The phenomena are argued to be expected\ngenerally in glass-forming mixtures."
    },
    {
        "anchor": "Mesoscopic fluctuations and intermittency in aging dynamics: The configurational de-correlation in an aging system is attributed to\nirreversible intermittent rearrangements, which are described as a Poisson\nprocess with average $\\propto \\ln(1 + t/t_w)$, where $t$ is the observation\ntime and $t_w$ is the age [P. Sibani and H.J. Jensen, Europhys. Lett. 69,\n2005]. On this basis, we obtain a simple model for the off-equilibrium aging\nbehavior of the autocorrelation: the average autocorrelation decays\nalgebraically, and its shifted and rescaled probability density function (PDF)\nhas a Gumbel-like shape which approaches a Gaussian at large times and becomes\nsharp in the thermodynamic limit. The model properties are tested against\nsimulations of the Edwards-Anderson spin glass, and are in reasonable agreement\nwith other available data.",
        "positive": "Kinematic irreversibility in surfactant-laden interfaces: The surface shear viscosity of an insoluble surfactant monolayer often\ndepends strongly on its surface pressure. Here, we show that a particle moving\nwithin a bounded monolayer breaks the kinematic reversibility of\nlow-Reynolds-number flows. The Lorentz reciprocal theorem allows such\nirreversibilities to be computed without solving the full nonlinear equations,\ngiving the leading-order contribution of surface-pressure-dependent surface\nviscosity. In particular, we show that a disk translating or rotating near an\ninterfacial boundary experiences a force in the direction perpendicular to that\nboundary. In unbounded monolayers, coupled modes of motion can also lead to\nnon-intuitive trajectories, which we illustrate using an interfacial analog of\nthe Magnus effect. This perturbative approach can be extended to more complex\ngeometries, and to 2D suspensions more generally."
    },
    {
        "anchor": "Dissipation in Langevin Equation and Construction of Mobility Tensor\n  from Dissipative Heat Flow: The rheological behavior of a material is strongly related to the energy\ndissipation, and the understanding and modeling of dissipation is important\nfrom the view point of rheology. To study rheological properties with some\nmesoscopic and macroscopic dynamics models, the modeling of dynamic equation\nwhich appropriately incorporates the dissipation is important. Although there\nare several methods to construct mesoscopic and macroscopic dynamic equations,\nsuch as the Onsager's method, their validity is not fully clear. In this work,\nwe theoretically analyze the dissipation in a mesoscopic Langevin equation in\ndetail, from the view point of stochastic energetics. We show that the\ndissipative heat flow from the heat bath to the system plays an important role\nin the mesoscopic dynamics. The dissipative heat flow is unchanged under the\nvariable transform, and thus it is a covariant quantity. We show that we can\nconstruct the Langevin equation and also perform a coarse-graining based on the\ndissipative heat flow. We can derive the mobility tensor from the dissipative\nheat flow, and construct the Langevin equation by combining it and the free\nenergy. Our method can be applied to various systems, such as the dumbbell\nmodel and the diffusion type equation for the density field, to give the\ncoarse-grained dynamic equations for them.",
        "positive": "Self-replicating segregation patterns in horizontally vibrated binary\n  mixture of granules: When granular mixtures of different sizes are fluidized, each species\nspontaneously separates and condenses to form patterns. Although granular\nsegregation has been extensively studied, the inability to directly observe the\ntime evolution of the internal structure hinders the understanding of the\nmechanism of segregation dynamics driven by surface flow. In this study, we\nreport rich band dynamics, including a self-replicating band, in a horizontally\nshaken granular mixture in a quasi-two-dimensional container where the granules\nformed steady surface waves. Direct observation of surface flow and segregated\ninternal structure revealed that coupling among segregation, surface flow, and\nhysteresis in the fluidity of granules is key to understanding complex band\ndynamics."
    },
    {
        "anchor": "A classical long-time tail in a driven granular fluid: I derive a mode-coupling theory for the velocity autocorrelation function,\n\\psi(t), in a fluid of randomly driven inelastic hard spheres far from\nequilibrium. With this, I confirm a conjecture from simulations that the\nvelocity autocorrelation function decays algebraically, \\psi(t) ~ t^{-3/2}, if\nmomentum is conserved. I show that the slow decay is due to the coupling to\ntransverse currents.",
        "positive": "Rayleigh waves and surface stability for Bell materials in compression;\n  comparison with rubber: The stability of a Bell-constrained half-space in compression is studied. To\nthis end, the propagation of Rayleigh waves on the surface of the material when\nit is maintained in a static state of triaxial prestrain is considered. The\nprestrain is such that the free surface of the half-space is a principal plane\nof deformation. The exact secular equation is established for surface waves\ntraveling in a principal direction of strain with attenuation along the\nprincipal direction normal to the free plane. As the half-space is put under\nincreasing compressive loads, the speed of the wave eventually tends to zero\nand the bifurcation criterion, or stability equation, is reached.\n  Then the analysis is specialized to specific forms of strain energy functions\nand prestrain, and comparisons are made with results previously obtained in the\ncase of incompressible neo-Hookean or Mooney-Rivlin materials. It is found that\nthese rubber-like incompressible materials may be compressed more than \"Bell\nempirical model\" materials, but not as much as \"Bell simple hyperelastic\"\nmaterials, before the critical stretches, solutions to the bifurcation\ncriterion, are reached. In passing, some classes of incompressible materials\nwhich possess a relative-universal bifurcation criterion are presented."
    },
    {
        "anchor": "Polymer induced depletion potentials in polymer-colloid mixtures: The depletion interactions between two colloidal plates or between two\ncolloidal spheres, induced by interacting polymers in a good solvent, are\ncalculated theoretically and by computer simulations. A simple analytical\ntheory is shown to be quantitatively accurate for case of two plates. A related\ndepletion potential is derived for two spheres; it also agrees very well with\ndirect computer simulations. Theories based on ideal polymers show important\ndeviations with increasing polymer concentration: They overestimate the range\nof the depletion potential between two plates or two spheres at all densities,\nwith the largest relative change occurring in the dilute regime. They\nunderestimate the well depth at contact for the case of two plates, but\noverestimate it for two spheres. Depletion potentials are also calculated using\na coarse graining approach which represents the polymers as ``soft colloids'':\ngood agreement is found in the dilute regime. Finally, the effect of the\npolymers on colloid-colloid osmotic virial coefficients is related to phase\nbehavior of polymer-colloid mixtures.",
        "positive": "Effect of externally deposited nanoscale heterogeneities in thin polymer\n  films on their adhesion behavior: Adhesion between two surfaces depend on the chemical and the mechanical\nproperties of both the materials. However, heterogeneities (surface or bulk)\naffect the adhesion between the two surfaces tremendously. In this work, we\nstudy the role of externally deposited nanoscale heterogeneities on their\nadhesion behavior. Silica nanoparticles in the bulk polydimethylsiloxane (PDMS)\npolymer matrix act as external heterogeneities, which subsequently affect their\nadhesion. The nanoscale heterogeneities change the polymer environment locally,\nwhich subsequently modify its mechanical properties, e.g. elastic modulus, as a\nresult, it affects its adhesion behavior. We observe that the adhesion behavior\nvary in nonlinear manner with increasing nanoparticle concentration. Therefore,\nprobing these heterogeneities may allow us to understand the emergence of\nprocessing-induced deviations and the role of external defects in the\nmacroscopic properties of a polymer."
    },
    {
        "anchor": "Effective potentials in a bidimensional vibrated granular gas: We present a numerical study of the spatial correlations of a\nquasi-two-dimensional granular fluid kept in a non-static steady state via\nvertical shaking. The simulations explore a wide range of packing fractions,\nvertical accelerations and restitution coefficients, always staying below the\ncrystallization limit. From the simulations we obtain the relevant Pair\nDistribution Functions (PDFs), and effective potentials for the interparticle\ninteraction are extracted from these PDFs via the Ornstein-Zernike equation\nwith the Percus-Yevick closure. The correlations in the granular structures\noriginating from these effective potentials are checked against the originating\nPDF using standard Monte Carlo simulations, and we find in general an excellent\nagreement. The resulting effective potentials show an increase of the spatial\ncorrelation at contact with the decreasing values of the restitution\ncoefficient, and a general tendency of the potentials to display deeper wells\nfor more dissipative dynamics. An exception to this general trend appears for\ncertain combinations of density and forcing, where resonant bouncing increases\ncorrelations.",
        "positive": "Structural, mechanical, and vibrational properties of particulate\n  physical gels: Our lives are surrounded by a rich assortment of disordered materials. In\nparticular, glasses are well known as dense, amorphous materials, whereas gels\nexist in low-density, disordered states. Recent progress has provided a\nsignificant step forward in understanding the material properties of glasses,\nsuch as mechanical, vibrational, and transport properties. In contrast, our\nunderstanding of particulate physical gels is still highly limited. Here, using\nmolecular dynamics simulations, we study a simple model of particulate physical\ngels, the Lennard-Jones (LJ) gels, and provide a comprehensive understanding of\ntheir structural, mechanical, and vibrational properties, all of which are\nmarkedly different from those of glasses. First, the LJ gels show sparse,\nheterogeneous structures, and the length scale $\\xi_s$ of the structures grows\nas the density is lowered. Second, the gels are extremely soft, with both shear\n$G$ and bulk $K$ moduli being orders of magnitude smaller than those of\nglasses. Third, many low-frequency vibrational modes are excited, which form a\ncharacteristic plateau with the onset frequency $\\omega_\\ast$ in the\nvibrational density of states. Structural, mechanical, and vibrational\nproperties, characterized by $\\xi_s$, $G$, $K$, and $\\omega_\\ast$,\nrespectively, show power-law scaling behaviors with the density, which\nestablishes a close relationship between them. Throughout the present work, we\nreveal that gels are multiscale, solid-state materials: (i) homogeneous elastic\nbodies at long lengths, (ii) heterogeneous elastic bodies with fractal\nstructures at intermediate lengths, and (iii) amorphous structural bodies at\nshort lengths."
    },
    {
        "anchor": "Numerical calculations of effective elastic properties of two cellular\n  structures: Young's moduli of regular two-dimensional truss-like and eye-shape-like\nstructures are simulated by using the finite element method. The structures are\nthe idealizations of soft polymeric materials used in the electret\napplications. In the simulations size of the representative smallest units are\nvaried, which changes the dimensions of the cell-walls in the structures. A\npower-law expression with a quadratic as the exponential term is proposed for\nthe effective Young's moduli of the systems as a function of the solid volume\nfraction. The data is divided into three regions with respect to the volume\nfraction; low, intermediate and high concentrations. The parameters of the\nproposed power-law expression in each region are later represented as a\nfunction of the structural parameters, unit-cell dimensions. The presented\nexpression can be used to predict structure/property relationship in materials\nwith similar cellular structures. It is observed that the structures with\nvolume fractions of solid higher than 0.15 exhibit the importance of the\ncell-wall thickness contribution in the elastic properties. The cell-wall\nthickness is the most significant factor to predict the effective Young's\nmodulus of regular cellular structures at high volume fractions of solid. At\nlower concentrations of solid, eye-like structure yields lower Young's modulus\nthan the truss-like structure with the similar anisotropy. Comparison of the\nnumerical results with those of experimental data of poly(propylene) show good\naggreement regarding the influence of cell-wall thickness on elastic properties\nof thin cellular films.",
        "positive": "Direct Evidence for an Absorbing Phase Transition Governing Yielding of\n  a Soft Glass: We present the first direct experimental evidence showing that yielding of a\nprototypical soft solid - a colloidal glass - is a non-equilibrium 'absorbing'\nphase transition. By simultaneously quantifying single-particle dynamics and\nbulk mechanical response, we extracted critical exponents for the order\nparameter and the relaxation time and found that this transition belongs to the\nconserved directed percolation universality class. In addition, the observed\ncritical slowing down is accompanied by a growing correlation length associated\nwith the size of regions of high Debye-Waller factor which are precursors to\nyield events in glasses. Our results show unambiguously that yielding of soft\nsolids falls squarely in the realm of non-equilibrium critical phenomena."
    },
    {
        "anchor": "Local Plasticity as the Source of Creep and Slow Dynamics in Granular\n  Materials: Creep mechanisms in uniaxially compressed 3D granular solids comprised of\nfaceted frictionless grains are studied numerically using a constant pressure\nand constant stress simulation method. Rapid uniaxial compression followed by\nslow dilation is predicted on the basis of a logarithmic creep phenomenon.\nMicromechanical analysis indicates the existence of a correlation between\ngranular creep and grain-scale deformations. Localized regions of large strain\nappear during creep and grow in magnitude and size with time. Furthermore, the\naccumulation of non-affine granular displacements increases linearly with local\nstrain, thereby providing insights into the origins of plastic dissipation\nduring stress-driven creep evolution. The prediction of slow logarithmic\ndynamics in the absence of friction indicates a universality in the role of\nplastic dissipation during the creep of granular solids.",
        "positive": "Dynamical regimes and hydrodynamic lift of viscous vesicles under shear: The dynamics of two-dimensional viscous vesicles in shear flow, with\ndifferent fluid viscosities $\\eta_{\\rm in}$ and $\\eta_{\\rm out}$ inside and\noutside, respectively, is studied using mesoscale simulation techniques.\nBesides the well-known tank-treading and tumbling motions, an oscillatory\nswinging motion is observed in the simulations for large shear rate. The\nexistence of this swinging motion requires the excitation of higher-order\nundulation modes (beyond elliptical deformations) in two dimensions.\nKeller-Skalak theory is extended to deformable two-dimensional vesicles, such\nthat a dynamical phase diagram can be predicted for the reduced shear rate and\nthe viscosity contrast $\\eta_{\\rm in}/\\eta_{\\rm out}$. The simulation results\nare found to be in good agreement with the theoretical predictions, when\nthermal fluctuations are incorporated in the theory. Moreover, the hydrodynamic\nlift force, acting on vesicles under shear close to a wall, is determined from\nsimulations for various viscosity contrasts. For comparison, the lift force is\ncalculated numerically in the absence of thermal fluctuations using the\nboundary-integral method for equal inside and outside viscosities. Both methods\nshow that the dependence of the lift force on the distance $y_{\\rm {cm}}$ of\nthe vesicle center of mass from the wall is well described by an effective\npower law $y_{\\rm {cm}}^{-2}$ for intermediate distances $0.8 R_{\\rm p}\n\\lesssim y_{\\rm {cm}} \\lesssim 3 R_{\\rm p}$ with vesicle radius $R_{\\rm p}$.\nThe boundary-integral calculation indicates that the lift force decays\nasymptotically as $1/[y_{\\rm {cm}}\\ln(y_{\\rm {cm}})]$ far from the wall."
    },
    {
        "anchor": "Phase separation and dynamical arrest of protein solutions dominated by\n  short-range attractions: The interplay of phase separation and dynamical arrest can lead to the\nformation of gels and glasses, which is relevant for such diverse fields as\nhard and soft condensed matter physics, materials science, food engineering and\npharmaceutical industry. Here, the non-equilibrium states as well as the\ninteractions of globular proteins are analyzed. Lysozyme in brine is chosen as\na model system with short-range attractions. The metastable gas-liquid binodal\nand the dynamical arrest line as well as the second virial coefficient $B_2$\nhave been determined for various solution conditions by cloud-point\nmeasurements, optical microscopy, centrifugation experiments and light\nscattering. If temperature is expressed in terms of $B_2$, the binodals\nobtained under various conditions fall onto a master curve, as suggested by the\nextended law of corresponding states. Arrest lines for different salt\nconcentrations overlap within experimental errors, whereas they do not overlap\nif the temperature axis is replaced by $B_2$. This indicates that the binodals\nare not sensitive to the details of the potential, but can be described by one\nintegral parameter, i.e. $B_2$, whereas the arrest line appears governed by its\nattractive part. The experimental findings are supported by numerical results\nof the non-equilibrium self-consistent generalized Langevin equation theory.",
        "positive": "On the connected-charges Thomson problem: We investigate the modifications brought about by the linear connectivity\namong charges in the classical Thomson problem. Instead of packing with local\nhexagonal order intersperced with topological defects, we find charge\ndistributions with helical symmetry wound around the surface of the sphere.\nThis finding should have repercussions in the viral packing and macroion\nadsorption theories."
    },
    {
        "anchor": "Visualization, coarsening and flow dynamics of focal conic domains in\n  simulated Smectic-A liquid crystals: Smectic liquid crystals vividly illustrate the subtle interplay of broken\ntranslational and orientational symmetries, by exhibiting defect structures\nforming geometrically perfect confocal ellipses and hyperbolas. Here, we\ndevelop and numerically implement an effective theory to study the dynamics of\nfocal conic domains in smectic-A liquid crystals. We use the information about\nthe smectic's structure and energy density provided by our simulations to\ndevelop several novel visualization tools for the focal conics. Our simulations\naccurately describe both simple and extensional shear, which we compare to\nexperiments, and provide additional insight into the coarsening dynamics of\nfocal conic domains.",
        "positive": "Feedback-controlled microbubble generator producing one million\n  monodisperse bubbles per second: Monodisperse lipid-coated microbubbles are a promising route to unlock the\nfull potential of ultrasound contrast agents for medical diagnosis and therapy.\nHere, we present a stand-alone lab-on-a-chip instrument that allows\nmicrobubbles to be formed with high monodispersity at high production rates.\nKey to maintaining a long-term stable, controlled, and safe operation of the\nmicrofluidic device with full control over the output size distribution is an\noptical transmission based measurement technique that provides real-time\ninformation on production rate and bubble size. We feed the data into a\nfeedback loop and demonstrate that this system can control the on-chip bubble\nradius (2.5 to 20 $\\mu$m) and the production rate up to $10^6$ bubbles/s. The\nfreshly formed phospholipid-coated bubbles stabilize after their formation to a\nsize approximately two times smaller than their initial on-chip bubble size\nwithout loss of monodispersity. The feedback control technique allows for full\ncontrol over the size distribution of the agent and can aid the development of\nmicrofluidic platforms operated by non-specialist end users."
    },
    {
        "anchor": "How heat controls fracture: the thermodynamics of creeping and\n  avalanching cracks: While of paramount importance in material science, the dynamics of cracks\nstill lacks a complete physical explanation. The transition from their slow\ncreep behavior to a fast propagation regime is a notable key, as it leads to\nfull material failure if the size of a fast avalanche reaches that of the\nsystem. We here show that a simple thermodynamics approach can actually account\nfor such complex crack dynamics, and in particular for the non-monotonic\nforce-velocity curves commonly observed in mechanical tests on various\nmaterials. We consider a thermally activated failure process that is coupled\nwith the production and the diffusion of heat at the fracture tip. In this\nframework, the rise in temperature only affects the sub-critical crack dynamics\nand not the mechanical properties of the material. We show that this\ndescription can quantitatively reproduce the rupture of two different polymeric\nmaterials (namely, the mode I opening of polymethylmethacrylate (PMMA) plates,\nand the peeling of pressure sensitive adhesive (PSA) tapes), from the very slow\nto the very fast fracturing regimes, over seven to nine decades of crack\npropagation velocities. In particular, the fastest regime is obtained with an\nincrease of temperature of thousands of kelvins, on the molecular scale around\nthe crack tip. Although surprising, such an extreme temperature is actually\nconsistent with different experimental observations that accompany the fast\npropagation of cracks, namely, fractoluminescence (i.e., the emission of\nvisible light during rupture) and a complex morphology of post-mortem fracture\nsurfaces, which could be due to the sublimation of bubbles.",
        "positive": "Wannier states and Bose-Hubbard parameters for 2D optical lattices: We consider the physical implementation of a 2D optical lattice with schemes\ninvolving 3 and 4 light fields. We illustrate the wide range of geometries\navailable to the 3 beam lattice, and compare the general potential properties\nof the two lattice schemes. Numerically calculating the band structure we\nobtain the Wannier states and evaluate the parameters of the Bose-Hubbard\nmodels relevant to these lattices. Using these results we demonstrate lattices\nthat realize Bose-Hubbard models with 2, 4, or 6 nearest neighbors, and\nquantify the extent that these different lattices effect the superfluid to\nMott-insulator transition."
    },
    {
        "anchor": "Nucleation and growth in one dimension, part II: Application to DNA\n  replication kinetics: Inspired by recent experiments on DNA replication, we apply a one-dimensional\nnucleation-and-growth model to DNA-replication kinetics, focusing on how to\nextract the time-dependent nucleation rate I(t) and growth speed v from data.\nWe discuss generic experimental problems, namely spatial inhomogeneity,\nmeasurement noise, and finite-size effects. After evaluating how each of these\naffects the measurements of I(t) and v, we give guidelines for the design of\nexperiments. These ideas are then discussed in the context of the\nDNA-replication experiments.",
        "positive": "Light-controllable chiral dopant based on azo-fragment: synthesis and\n  characterization: We present the newly synthesized chiral dopant\n2-[(2-isopropyl-5-methylcyclohexyl)oxy]-2-oxoethyl\n4-{(E)-[4-(decyloxy)phenyl]diazenyl}benzoate (ChD-3501), consisting of azo- and\naliphatic fragments together with a chiral center based on l-menthol as a\nreversible light-controllable chiral dopant. To assess the effects of UV/VIS\nirradiation and temperature in the isotropic and liquid crystalline (LC)\nstates, we studied the spectral kinetics of ethanol solution of ChD-3501, as\nwell as induction of the cholesteric helix when it was dissolved in nematic LC\n(E7) as a chiral dopant. The concentration dependence of the helical pitch of\nthe induced cholesterics was studied by means on Grandjean-Cano method, and the\nhelical twisting power of ChD-3501 in the nematic host E7 was determined. The\nreversible trans-cis isomerization of chiral dopandt ChD-3501 in E7 under\nUV/VIS irradiation was studied, and it has been found that the storage of the\ncis-isomer at certain constant temperature also leads to the reversible\nisomerisation, which presents a certain interest for applications."
    },
    {
        "anchor": "Tubulation and dispersion of oil by bacterial growth on droplets: Bacteria on surfaces exhibit collective behaviors, such as active turbulence\nand active stresses, which result from their motility, growth, and interactions\nwith their local surroundings. However, interfacial deformations on soft\nsurfaces and liquid interfaces caused by active growth, particularly over long\ntime scales, are not well understood. Here, we describe experimental\nobservations on the emergence of tubular structures arising from the growth of\nrod-shaped bacteria at the interface of oil droplets in water. Using\nmicrofluidics and timelapse microscopy, the dimensions and extension rates of\nindividual tubular structures as well as bulk bio-aggregate formation are\nquantified for hundreds of droplets over 72 hours. Tubular structures are\ncomparable in length to the initial droplet radius and are composed of an outer\nshell of bacteria that stabilize an inner filament of oil. The oil filament\nbreaks up into smaller microdroplets dispersed within the bacterial shell. This\nwork provides insight into active stresses at deformable interfaces and\nimproves our understanding of microbial oil biodegradation and its potential\ninfluence on the transport of droplets in the ocean water column.",
        "positive": "Domain Structures of Smectic Films Formed by Bent-Shaped Molecules: We formulate a simple Landau type model describing macroscopic behaviour\nrecently discovered new smectic phases composed of achiral bent-shaped\nmolecules. Films of such smectics exhibit three types of ordering related to\ndipole polarization, molecular tilt, and chirality. However due to specific\nthird order coupling of the order parameters these three types of\nsymmetry-breaking are not independent ones, and this fact leads to specific\ndomain structures really observed in experiments."
    },
    {
        "anchor": "A Lattice-Boltzmann model for suspensions of self-propelling colloidal\n  particles: We present a Lattice-Boltzmann method for simulating self-propelling (active)\ncolloidal particles in two-dimensions. Active particles with symmetric and\nasymmetric force distribution on its surface are considered. The velocity field\ngenerated by a single active particle, changing its orientation randomly, and\nthe different time scales involved are characterized in detail. The steady\nstate speed distribution in the fluid, resulting from the activity, is shown to\ndeviate considerably from the equilibrium distribution.",
        "positive": "Time-Rate-Transformation framework for targeted assembly of short-range\n  attractive colloidal suspensions: The aggregation of attractive colloids has been extensively studied from both\ntheoretical and experimental perspectives as the fraction of solid particles is\nchanged, and the range, type and strength of attractive or repulsive forces\nbetween particles varies. The resulting gels consisting of disordered\nassemblies of attractive colloidal particles, have also been investigated with\nregards to percolation, phase separation, and the mechanical characteristics of\nthe resulting fractal networks. Despite tremendous progress in our\nunderstanding of the gelation process, and the exploration of different routes\nfor arresting the dynamics of attractive colloids, the complex interplay\nbetween convective transport processes and many-body effects in such systems\nhas limited our ability to drive the system towards a specific configuration.\nHere we study a model attractive colloidal system over a wide range of particle\ncharacteristics and flow conditions undergoing aggregation far from\nequilibrium. The complex multiscale dynamics of the system can be understood\nusing a Time-Rate-Transformation diagram adapted from understanding of\nmaterials processing in block copolymers, supercooled liquids and much stiffer\nglassy metals to direct targeted assembly of attractive colloidal particles."
    },
    {
        "anchor": "Sound of Interfacial Flows: Unraveling the Forces Shaping Fast Capillary\n  Flows using their Acoustic Signature: Many familiar events feature a distinctive sound: paper crumpling or tearing,\nsqueaking doors, drumming rain or boiling water. Such characteristic sounds\nactually carry a profusion of informations about the fleeting physical\nprocesses at the root of acoustic emission, which appears appealing especially\nin situations precluding direct or in-situ measurements, such as e.g. the\nrupture of micron-thick liquid sheet. Here we report on such a link between\nfast interfacial hydrodynamics and sound. The acoustic emission of a bursting\nsoap bubble is captured by means of antennae and deciphered with the conceptual\nframework of aeroacoustics. This reveals that capillary forces, thin-film\nhydrodynamics, but also out-of-equilibrium surfactants dynamics all shape the\ncapillary burst sound. Whereas ultra-fast imagery only captures the shapes of\nflows, the acoustic signature radiated by hydrodynamical forces offers a timely\ncomplement for it allows a direct experimental access to these dynamical\nquantities.",
        "positive": "Capillary Forces on a Small Particle at a Liquid-Vapor Interface: Theory\n  and Simulation: We study the meniscus on the outside of a small spherical particle with\nradius $R$ at a liquid-vapor interface. The liquid is confined in a cylindrical\ncontainer with a finite radius $L$ and has a contact angle $\\pi/2$ at the\ncontainer surface. The center of the particle is placed at various heights\nalong the central axis of the container. By varying $L$, we are able to\nsystematically study the crossover of the meniscus from nanometer to\nmacroscopic scales. The meniscus rise or depression on the particle is found to\ngrow as $\\ln (2L/R)$ when $R\\ll L\\ll \\kappa^{-1}$ with $\\kappa^{-1}$ being the\ncapillary length and saturate to a value predicted by the Derjaguin-James\nformula when $R \\ll \\kappa^{-1} \\ll L$. The capillary force on the particle\nexhibits a linear dependence on the particle's displacement from its\nequilibrium position at the interface when the displacement is small. The\nassociated spring constant is found to be $2\\pi\\gamma\\ln^{-1} (2L/R)$ for $L\\ll\n\\kappa^{-1}$ and saturates to $2\\pi\\gamma\\ln^{-1} (3.7\\kappa^{-1}/R)$ for $L\\gg\n\\kappa^{-1}$. At nanometer scales, we perform molecular dynamics simulations of\nthe described geometry and the results agree well with the predictions of the\nmacroscopic theory of capillarity. At micrometer to macroscopic scales,\ncomparison to experiments by Anachkov \\textit{et al.} [Soft Matter {\\bf 12},\n7632 (2016)] shows that the finite span of a liquid-vapor or liquid-liquid\ninterface needs to be considered to interpret experimental data collected with\n$L \\sim \\kappa^{-1}$."
    },
    {
        "anchor": "A phase space approach to supercooled liquids and a universal collapse\n  of their viscosity: A broad fundamental understanding of the mechanisms underlying the\nphenomenology of supercooled liquids has remained elusive, despite decades of\nintense exploration. When supercooled beneath its characteristic melting\ntemperature, a liquid sees a sharp rise in its viscosity over a narrow\ntemperature range, eventually becoming frozen on laboratory timescales.\nExplaining this immense increase in viscosity is one of the principle goals of\ncondensed matter physicists. To that end, numerous theoretical frameworks have\nbeen proposed which explain and reproduce the temperature dependence of the\nviscosity of supercooled liquids. Each of these frameworks appears only\napplicable to specific classes of glassformers and each possess a number of\nvariable parameters. Here we describe a classical framework for explaining the\ndynamical behavior of supercooled liquids based on statistical mechanical\nconsiderations, and possessing only a single variable parameter. This parameter\nvaries weakly from liquid to liquid. Furthermore, as predicted by this new\nclassical theory and its earlier quantum counterpart, we find with the aid of a\nsmall dimensionless constant that varies in size from $\\sim 0.05-0.12$, a\nuniversal (16 decade) collapse of the viscosity data as a function of\ntemperature. The collapse appears in all known types of glass forming\nsupercooled liquids (silicates, metallic alloys, organic systems, chalcogenide,\nsugars, and water).",
        "positive": "Relationship between Local Molecular Field Theory and Density Functional\n  Theory for non-uniform liquids: The Local Molecular Field Theory (LMF) developed by Weeks and co-workers has\nproved successful for treating the structure and thermodynamics of a variety of\nnon-uniform liquids. By reformulating LMF in terms of one-body direct\ncorrelation functions we recast the theory in the framework of classical\nDensity Functional Theory (DFT). We show that the general LMF equation for the\neffective reference potential phi_R follows directly from the standard\nmean-field DFT treatment of attractive interatomic forces. Using an accurate\n(Fundamental Measures) DFT for the non-uniform hard-sphere reference fluid we\ndetermine phi_R for a hard-core Yukawa liquid adsorbed at a planar hard wall.\nIn the approach to bulk liquid-gas coexistence we find the effective potentials\nexhibit rich structure that can include damped oscillations at large distances\nfrom the wall as well as the repulsive hump near the wall required to generate\nthe low density 'gas' layer characteristic of complete drying. We argue that it\nwould be difficult to obtain the same level of detail from other (non DFT\nbased) implementations of LMF. LMF emphasizes the importance of making an\nintelligent division of the interatomic pair potential of the full system into\na reference part and a remainder that can be treated in mean-field\napproximation. We investigate different divisions for an exactly solvable one-\ndimensional model where the pair potential has a hard-core plus a linear\nattractive tail. Results for the structure factor and the equation of state of\nthe uniform fluid show that including a significant portion of the attraction\nin the reference system can be much more accurate than treating the full\nattractive tail in mean-field approximation. We discuss further aspects of the\nrelationship between LMF and DFT."
    },
    {
        "anchor": "Transitions to Nematic states in homogeneous suspensions of high aspect\n  ratio magnetic rods: Isotropic-Nematic and Nematic-Nematic transitions from a homogeneous base\nstate of a suspension of high aspect ratio, rod-like magnetic particles are\nstudied for both Maier-Saupe and the Onsager excluded volume potentials. A\ncombination of classical linear stability and asymptotic analyses provides\ninsight into possible nematic states emanating from both the isotropic and\nnematic non-polarized equilibrium states. Local analytical results close to\ncritical points in conjunction with global numerical results (Bhandar, 2002)\nyields a unified picture of the bifurcation diagram and provides a convenient\nbase state to study effects of external orienting fields.",
        "positive": "Anticipated synchronization in coupled inertia ratchets with\n  time-delayed feedback: a numerical study: We investigate anticipated synchronization between two periodically driven\ndeterministic, dissipative inertia ratchets that are able to exhibit directed\ntransport with a finite velocity. The two ratchets interact through an\nunidirectional delay coupling: one is acting as a master system while the other\none represents the slave system. Each of the two dissipative deterministic\nratchets is driven externally by a common periodic force. The delay coupling\ninvolves two parameters: the coupling strength and the (positive-valued) delay\ntime. We study the synchronization features for the unbounded, current carrying\ntrajectories of the master and the slave, respectively, for four different\nstrengths of the driving amplitude. These in turn characterize differing phase\nspace dynamics of the transporting ratchet dynamics: regular, intermittent and\na chaotic transport regime. We find that the slave ratchet can respond in\nexactly the same way as the master will respond in the future, thereby\nanticipating the nonlinear directed transport."
    },
    {
        "anchor": "A test for the existence of isomorphs in glass-forming materials: We describe a method to determine whether a material has isomorphs in its\nthermodynamic phase diagram. Isomorphs are state points for which various\nproperties are invariant in reduced units. Such materials are commonly\nidentified from strong correlation between thermal fluctuations of the\npotential energy, U, and the virial W, but this identification is not generally\napplicable to real materials. We show from molecular dynamic simulations of\natomic, molecular, and polymeric materials that systems with strong U-W\ncorrelation cannot be pressure densified; that is, the density obtained on\ncooling to the glassy state and releasing the pressure is independent of the\npressure applied during cooling.",
        "positive": "The fraction of condensed counterions around a charged rod: Comparison\n  of Poisson-Boltzmann theory and computer simulations: We investigate the phenomenon of counterion condensation in a solution of\nhighly charged rigid polyelectrolytes within the cell model. A method is\nproposed which -- based on the charge distribution function -- identifies both\nthe fraction of condensed ions and the radial extension of the condensed layer.\nWithin salt-free Poisson-Boltzmann (PB) theory it reproduces the well known\nfraction 1-1/xi of condensed ions for a Manning parameter xi>1. Furthermore, it\npredicts a weak salt dependence of this fraction and a breakdown of the concept\nof counterion condensation in the high salt limit. We complement our\ntheoretical investigations with molecular dynamics simulations of a cell-like\nmodel, which constantly yield a stronger condensation than predicted by PB\ntheory. While the agreement between theory and simulation is excellent in the\nmonovalent, weakly charged case, it deteriorates with increasing electrostatic\ninteraction strength and, in particular, increasing valence. For instance, at a\nhigh concentration of divalent salt and large xi our computer simulations\npredict charge oscillations, which mean-field theory is unable to reproduce."
    },
    {
        "anchor": "Why is nacre strong? II: remaining mechanical weakness for cracks\n  propagating along the sheets: In our previous paper (Eur. Phys. J. E 4, 121 (2001)) we proposed a\ncoarse-grained elastic energy for nacre, or stratified structure of hard and\nsoft layers. We then analyzed a crack running perpendicular to the layers and\nsuggested one possible reason for the enhanced toughness of this substance. In\nthe present paper, we consider a crack running parallel to the layers. We\npropose a new term added to the previous elastic energy, which is associated\nwith the bending of layers. We show that there are two regimes for the\nparallel-fracture solution of this elastic energy; near the fracture tip the\ndeformation field is governed by a parabolic differential equation while the\nfield away from the tip follows the usual elliptic equation. Analytical results\nshow that the fracture tip is lenticular, as suggested in a paper on a smectic\nliquid crystal (P. G. de Gennes, Europhys. Lett. 13 (8), 709 (1990)). On the\ncontrary, away from the tip, the stress and deformation distribution recover\nthe usual singular behaviors (sqrt(x) and 1/sqrt(x), respectively, where x is\nthe distance from the tip). This indicates there is no enhancement in toughness\nin the case of parallel fracture.",
        "positive": "Salt-induced microheterogeneities in binary liquid mixtures: The salt-induced microheterogeneity (MH) formation in binary liquid mixtures\nis studied by small-angle X-ray scattering (SAXS) and liquid state theory.\nPrevious experiments have shown that this phenomenon occurs for antagonistic\nsalts, whose cations and anions prefer different components of the solvent\nmixture. However, so far the precise mechanism leading to the characteristic\nlength scale of MHs remained unclear. Here, it is shown that MHs can be\ngenerated by the competition of short-ranged interactions and long-ranged\nmonopole-dipole interactions. The experimental SAXS patterns can be\nquantitatively reproduced by fitting to the derived correlation functions\nwithout assuming any specific model. The dependency of the MH structure with\nrespect to ionic strength and temperature is analyzed. Close to the demixing\nphase transition, critical-like behavior occurs with respect to the spinodal\nline in the phase diagram."
    },
    {
        "anchor": "Dynamical Simulation of Nuclear \"Pasta\": Soft Condensed Matter in Dense\n  Stars: More than twenty years ago, it was predicted that nuclei can adopt\ninteresting shapes, such as rods or slabs, etc., in the cores of supernovae and\nthe crusts of neutron stars. These non-spherical nuclei are referred to as\nnuclear \"pasta\".\n  In recent years, we have been studying the dynamics of the pasta phases using\na method called quantum molecular dynamics (QMD) and have opened up a new\naspect of study for this system. Our findings include: dynamical formation of\nthe pasta phases by cooling down the hot uniform nuclear matter; phase diagrams\nin the density versus temperature plane; structural transitions between the\npasta phases induced by compression and elucidation of the mechanism by which\nthey proceed. In the present article, we given an overview of the basic physics\nand astrophysics of the pasta phases and review our works for readers in other\nfields.",
        "positive": "DNA-polymer architecture orchestrates the segregation and\n  spatio-temporal organization of E. coli chromosomes during replication in\n  slow growth: The mechanism and driving forces of chromosome segregation in the bacterial\ncell cycle of E. coli is one of the least understood events in its life cycle.\nUsing principles of entropic repulsion between polymer loops confined in a\ncylinder, we use Monte carlo simulations to show that the segregation dynamics\nis spontaneously enhanced by the adoption of a certain DNA-polymer architecture\nas replication progresses. Secondly, the chosen polymer-topology ensures its\nself-organization along the cell axis while segregation is in progress, such\nthat various chromosomal loci get spatially localized. The time evolution of\nloci positions quantitatively match the corresponding experimentally reported\nresults, including observation of the cohesion time and the ter-transition.\nAdditionally, the contact map generated using our bead-spring model reproduces\nthe four macro-domains of the experimental Hi-C maps. Lastly, the proposed\nmechanism reproduces the observed universal dynamics as the sister loci\nseparate during segregation.\n  It was already hypothesized and expected that SMC proteins, e.g. MukBEF\ncontribute over and above entropic repulsion between bacterial-DNA\nring-polymers to aid the segregation of daughter DNAs in the E.coli cell cycle.\nWe propose that cross-links (plausibly induced by SMC proteins) at crucial\npositions along the contour is enough to provide sufficient forces for\nsegregation within reasonable time scales. A mapping between Monte Carlo\ndiffusive dynamics time scales and real time units helps us use experimentally\nrelevant numbers for our modeling."
    },
    {
        "anchor": "Quantum vortices in optical lattices: A vortex in a superfluid gas inside an optical lattice can behave as a\nmassive particle moving in a periodic potential and exhibiting quantum\nproperties. In this Letter we discuss these properties and show that the\nexcitation of vortex motions in a two-dimensional lattice can lead to striking\nmeasurable changes in its dynamic response. It would be possible by means of\nBragg spectroscopy to carry out the first direct measurement of the effective\nvortex mass, the pinning to the underlying lattice, and the dissipative\ndamping.",
        "positive": "Surface Wetting of Liquid Nanodroplets: The spreading of liquid nanodroplets of different initial radii $R_{0}$ is\nstudied using molecular dynamics simulation. Results for two distinct systems,\nPb on Cu(111), which is non-wetting, and a coarse grained polymer model, which\nwets the surface, are presented for Pb droplets ranging in size from $\\sim55\n000$ to $220 000$ atoms and polymer droplets ranging in size from $\\sim200 000$\nto $780 000$ monomers. In both cases, a precursor foot precedes the spreading\nof the main droplet. This precursor foot spreads as $r_{f}^{2}(t)=2D_{eff}t$\nwith an effective diffusion constant that exhibits a droplet size dependence\n$D_{eff}\\sim R_{0}^{1/2}$. The radius of the main droplet $r_{b}(t)\\sim\nR_{0}^{4/5}$ in agreement with kinetic models for the cylindrical geometry\nstudied."
    },
    {
        "anchor": "Effect of attractions on correlation length scales in a glass-forming\n  liquid: There is growing evidence that slow dynamics and dynamic heterogeneity\npossess structural signatures in glass-forming liquids. However, even in the\nweakly frustrated glass-forming liquids, whether or not the dynamic\nheterogeneity has a structural origin is a matter of debate. Via molecular\ndynamics simulation, we present a study of examining the connection between\ndynamic heterogeneity and bond orientational order in a weakly frustrated\nglass-forming liquid in two dimensions by taking advantage of assessing the\neffect of attractions on the correlation length scales. We find that\nattractions can strongly affect relaxation dynamics, dynamic heterogeneity and\nthe associated dynamic correlation length of the liquid, but their influence on\nbond orientational order and the associated static correlation length shows a\nmanner reminiscent of the effect of attractions on the thermodynamics of\nliquids. This implies that the growth of bond orientational order and static\ncorrelation length scale might be merely a manifestation of favoring the\nconfigurational entropy in weakly frustrated glass-forming liquids. Thus, our\nresults lead strong evidence that bond orientational order cannot provide a\ncomplete description of dynamic heterogeneity even in weakly frustrated\nglass-forming systems.",
        "positive": "Electrostatically tunable small-amplitude free vibrations of pressurized\n  electro-active spherical balloons: Designing tunable resonators is of practical importance in active/adaptive\nsound generation, noise control, vibration isolation and damping. In this\npaper, we propose to exploit the biasing fields (induced by internal pressure\nand radial electric voltage) to tune the three-dimensional and small-amplitude\nfree vibration of a thick-walled soft electro-active (SEA) spherical balloon.\nThe incompressible isotropic SEA balloon is characterized by both neo-Hookean\nand Gent ideal dielectric models. The equations governing small-amplitude\nvibrations under inhomogeneous biasing fields can be linearized and solved in\nspherical coordinates using the state-space formalism, which establishes two\nseparate transfer relations correlating the state vectors at the inner surface\nwith those at the outer surface of the SEA balloon. By imposing the mechanical\nand electric boundary conditions, two separate analytical frequency equations\nare derived, which characterize two independent classes of vibration for\ntorsional and spheroidal modes, respectively. Numerical examples are finally\nconducted to validate the theoretical derivation as well as to investigate the\neffects of both radial electric voltage and internal pressure on the resonant\nfrequency of the SEA balloon. The reported analytical solution is truly and\nfully three-dimensional, covering from the purely radial breathing mode to\ntorsional mode to any general spheroidal mode, and hence provides a more\naccurate prediction of the vibration characteristics of tunable resonant\ndevices that incorporate the SEA spherical balloon as the tuning element."
    },
    {
        "anchor": "Lipid membrane-mediated attractions between curvature inducing objects: The interplay of membrane proteins is vital for many biological processes,\nsuch as cellular transport, cell division, and signal transduction between\nnerve cells. Theoretical considerations have led to the idea that the membrane\nitself mediates protein self-organization in these processes through\nminimization of membrane curvature energy. Here, we present a combined\nexperimental and numerical study in which we quantify these interactions\ndirectly for the first time. In our experimental model system we control the\ndeformation of a lipid membrane by adhering colloidal particles. Using confocal\nmicroscopy, we establish that these membrane deformations cause an attractive\ninteraction force leading to reversible binding. The attraction extends over\n2.5 times the particle diameter and has a strength of three times the thermal\nenergy (-3.3 kT). Coarse-grained Monte-Carlo simulations of the system are in\nexcellent agreement with the experimental results and prove that the measured\ninteraction is independent of length scale. Our combined experimental and\nnumerical results reveal membrane curvature as a common physical origin for\ninteractions between any membrane-deforming objects, from nanometre-sized\nproteins to micrometre-sized particles.",
        "positive": "Hydrodynamics and multiscale order in confluent epithelia: We formulate a hydrodynamic theory of confluent epithelia: i.e. monolayers of\nepithelial cells adhering to each other without gaps. Taking advantage of\nrecent progresses toward establishing a general hydrodynamic theory of p-atic\nliquid crystals, we demonstrate that collectively migrating epithelia feature\nboth nematic (i.e. p=2) and hexatic (i.e. p=6) order, with the former being\ndominant at large and the latter at small length scales. Such a remarkable\nmultiscale liquid crystal order leaves a distinct signature in the system's\nstructure factor, which exhibits two different power law scaling regimes,\nreflecting both the hexagonal geometry of small cells clusters, as well as the\nuniaxial structure of the global cellular flow. We support these analytical\npredictions with two different cell-resolved models of epithelia -- i.e. the\nself-propelled Voronoi model and the multiphase field model -- and highlight\nhow momentum dissipation and noise influence the range of fluctuations at small\nlength scales, thereby affecting the degree of cooperativity between cells. Our\nconstruction provides a theoretical framework to conceptualize the recent\nobservation of multiscale order in layers of Madin-Darby canine kidney cells\nand pave the way for further theoretical developments."
    },
    {
        "anchor": "Signal propagation and linear response in the delay Vicsek model: Retardation between sensation and action is an inherent biological trait.\nHere we study its effect in the Vicsek model, which is a paradigmatic swarm\nmodel. We find that: (i) a discrete time delay in the orientational\ninteractions diminishes the ability of strongly aligned swarms to follow a\nleader and, in return, increases their stability against random orientation\nfluctuations; (ii) both longer delays and higher speeds favor ballistic over\ndiffusive spreading of information (orientation) through the swarm; (iii) for\nshort delays, the mean change in the total orientation (the order parameter)\nscales linearly in a small orientational bias of the leaders and inversely in\nthe delay time, while its variance first increases and then saturates with\nincreasing delays; (iv) the linear response breaks down when orientation\nconservation is broken.",
        "positive": "Bending Mechanics of Biomimetic Scale Plates: We develop the fundamentals of nonlinear and anisotropic bending behavior of\nbiomimetic scale plates using a combination of analytical modeling, finite\nelement (FE) computations, and motivational experiments. The analytical\narchitecture-property relationships are derived for both synclastic and\nanticlastic curvatures. The results show that, as the scales engage, both\nsynclastic and anticlastic deformations show non-linear scale contact\nkinematics and cross-curvature sensitivity of moments resulting in strong\ncurvature-dependent elastic nonlinearity and emergent anisotropy. The\nanisotropy of bending rigidities and their evolution with curvature are\naffected by both the direction and magnitude of bending as well as scale\ngeometry parameters, and their distribution on the substrate. Like earlier\nbeam-like substrates, kinematic locked states were found to occur; however,\ntheir existence and evolution are also strongly determined by scale geometry\nand imposed cross-curvatures. This validated model helps us to quantify bending\nresponse, locking behavior, and their geometric dependence, paving the way for\na deeper understanding of the nature of nonlinearity and anisotropy of these\nsystems."
    },
    {
        "anchor": "Active Brownian motion with orientation-dependent motility: theory and\n  experiments: Combining experiments on active colloids, whose propulsion velocity can be\ncontrolled via a feedback loop, and theory of active Brownian motion, we\nexplore the dynamics of an overdamped active particle with a motility that\ndepends explicitly on the particle orientation. In this case, the active\nparticle moves faster when oriented along one direction and slower when\noriented along another, leading to an anisotropic translational dynamics which\nis coupled to the particle's rotational diffusion. We propose a basic model of\nactive Brownian motion for orientation-dependent motility. Based on this model,\nwe obtain analytic results for the mean trajectories, averaged over the\nBrownian noise for various initial configurations, and for the mean-square\ndisplacements including their anisotropic non-Gaussian behavior. The\ntheoretical results are found to be in good agreement with the experimental\ndata. Our findings establish a methodology to engineer complex anisotropic\nmotilities of active Brownian particles, with potential impact in the study of\nthe swimming behavior of microorganisms subjected to anisotropic driving\nfields.",
        "positive": "Mechanics of metric frustration in contorted filament bundles: From\n  local symmetry to columnar elasticity: Bundles of filaments are subject to geometric frustration: certain\ndeformations (e.g. bending while twisted) require longitudinal variations in\nspacing between filaments. While bundles are common -- from protein fibers to\nyarns -- the mechanical consequences of longitudinal frustration are unknown.\nWe derive a geometrically-nonlinear formalism for bundle mechanics, using a\ngauge-like symmetry under reptations along filament backbones. We relate force\nbalance to orientational geometry and assess the elastic cost of frustration in\ntwisted toroidal bundles."
    },
    {
        "anchor": "Diffusion and sedimentation in colloidal suspensions using multiparticle\n  collision dynamics with a discrete particle model: We study self-diffusion and sedimentation in colloidal suspensions of\nnearly-hard spheres using the multiparticle collision dynamics simulation\nmethod for the solvent with a discrete mesh model for the colloidal particles\n(MD+MPCD). We cover colloid volume fractions from 0.01 to 0.40 and compare the\nMD+MPCD simulations to Brownian dynamics simulations with free-draining\nhydrodynamics (BD) as well as pairwise far-field hydrodynamics described using\nthe Rotne--Prager--Yamakawa mobility tensor (BD+RPY). The dynamics in MD+MPCD\nsuggest that the colloidal particles are only partially coupled to the solvent\nat short times. However, the long-time self-diffusion coefficient in MD+MPCD is\ncomparable to that in BD and BD+RPY, and the sedimentation coefficient in\nMD+MPCD is in good agreement with that in BD+RPY, suggesting that MD+MPCD gives\na reasonable description of the hydrodynamic interactions in colloidal\nsuspensions. The discrete-particle MD+MPCD approach is convenient and readily\nextended to more complex shapes, and we determine the long-time self-diffusion\ncoefficient in suspensions of nearly-hard cubes to demonstrate its generality.",
        "positive": "Self similarity of liquid droplet coalescence in a quasi-2D\n  free-standing liquid-crystal film: Coalescence of droplets is an ubiquitous phenomenon in chemical, physical and\nbiolog-ical systems. The process of merging of liquid objects has been studied\nduring the pastyears experimentally and theoretically in different geometries.\nWe introduce a uniquesystem that allows a quasi two-dimensional description of\nthe coalescence process,micrometer-sized flat droplets in freely suspended\nsmectic liquid-crystal films. We findthat the bridge connecting the droplets\ngrows linearly in time during the initial stage ofcoalescence, both with\nrespect to its height and lateral width. We also verify self-similardynamics of\nthe bridge during the first stage of coalescence. We compare our resultswith a\nmodel based on the thin sheet equations."
    },
    {
        "anchor": "Membrane budding driven by intra-cellular ESCRT-III filaments: Exocytosis is a common transport mechanism via which cells transport out\nnon-essential macro-molecules (cargo) into the extra cellular space. ESCRT-III\nproteins are known to help in this. They polymerize into a conical spring like\nstructure and help deform the cell membrane locally into a bud which wrapps the\noutgoing cargo. we model this process using a continuum energy functional. It\nconsists of elastic energies of the membrane and the semi-rigid ESCRT-III\nfilament, favorable adhesion energy between the cargo and the membrane, and\naffinity among the ESCRT-III filaments. We take the free energy minimization\nroute to identify the sequence of composite structures which form during the\nprocess. We show that membrane adhesion of the cargo is the driving force for\nthis budding process and not the buckling of ESCRT-III filaments from flat\nspiral to conical spring shape. However ESCRT-III stabilizes the bud once it\nforms. Further we conclude that a non-equilibrium process is needed to pinch\noff/separate the stable bud (containing the cargo) from the cell body.",
        "positive": "Length-dependent translocation of polymers through nanochannels: We consider the flow-driven translocation of single polymer chains through\nnanochannels. Using analytical calculations based on the de Gennes blob model\nand mesoscopic numerical simulations, we estimate the threshold flux for the\ntranslocation of chains of different number of monomers. The translocation of\nthe chains is controlled by the competition between entropic and hydrodynamic\neffects, which set a critical penetration length for the chain before it can\ntranslocate through the channel. We demonstrate that the polymers show two\ndifferent translocation regimes depending on how their length under confinement\ncompares to the critical penetration length. For polymer chains longer than the\nthreshold, the translocation process is insensitive to the number of monomers\nin the chain as predicted in Sakaue {\\it et al.}, {\\it Euro. Phys. Lett.}, {\\bf\n72} 83 (2005). However, for chains shorter than the critical length we show\nthat the translocation process is strongly dependent on the length of the\nchain. We discuss the possible relevance of our results to biological\ntransport."
    },
    {
        "anchor": "Looking for a compact semi empirical equation of state for hard spheres:\n  possibility of a glassy transition and random loose packing: The equation of state of a hard sphere fluid at high density should exhibit a\nsimple pole at the random close packing limit. Here we show that trying to\nobtain a compact semi-empirical equation of state simultaneously compatible\nwith that asymptotic behaviour and with the known virial coefficients raises an\nanalytical difficulty which can be solved if a glassy transition occurs in the\ndisordered metastable phase at a density intermediate between the freezing\npoint and the random close packing limit, numerically close to the melting\npoint. The estimated value for the transition point, which is identified with\nrandom loose packing, is in good agreement with earlier estimations.",
        "positive": "Numerical studies of triangulated vesicles with anisotropic membrane\n  inclusions: In this study, we implement the deviatoric curvature model to examine\ndynamically triangulated surfaces with anisotropic membrane inclusions. The\nMonte-Carlo numerical scheme is devised to not only minimize the total bending\nenergy of the membrane but also the in-plane nematic order of the inclusions by\nconsidering the mismatch between the curvature of the membrane and the\nintrinsic curvature of the inclusion. Neighboring inclusions can either attract\nwith nearest-neighbor interaction or with a nematic interaction derived from\nliquid crystal theory. Orientational order determines whether vesicles fully\ncovered with inclusions result in bulbs connected by necks or long tubes.\nRemarkably, when inclusions on vesicles with no vacancies interact\nnon-nematically, a spontaneous local order can lead to a bulb transition which\nmay have implications in cell or organelle division. Furthermore we find that\naverage nematic order is inversely proportional to the number of thin necks\nformed in the vesicles. Our method shows good convergence and is suitable for\nfurther upgrades, for example to vesicles constrained by volume."
    },
    {
        "anchor": "Polymer translocation under a pulling force: scaling arguments and\n  threshold forces: DNA translocation through nanopores is one of the most promising strategies\nfor the next-generation sequencing technologies. Most part of experimental and\nnumerical works has focused on polymer translocation biased by electrophoresis,\nwhere a pulling force acts on the polymer within the nanopore. An alternative\nstrategy however is emerging, which uses optical or magnetic tweezers. In this\ncase, the pulling force is exerted directly at one end of the polymer, which\nstrongly modifies the translocation process. In this paper, we report numerical\nsimulations of both linear and structured (mimicking DNA) polymer models,\nsimple enough to allow for a statistical treatment of the pore structure\neffects on the translocation time probability distributions. Based on extremely\nextended computer simulation data, we : i) propose scaling arguments for an\nextension of the predicted translocation times $\\tau \\sim N^{2}F^{-1}$ over the\nmoderate forces range; ii) analyze the effect of pore size and polymer\nstructuration on translocation times $\\tau$.",
        "positive": "Rippling Instability of a Collapsing Bubble: When a bubble of air rises to the top of a highly viscous liquid, it forms a\ndome-shaped protuberance on the free surface. Unlike a soap bubble, it bursts\nso slowly as to collapse under its own weight simultaneously, and folds into a\nstriking wavy structure. This rippling effect occurs in fact for both elastic\nand viscous sheets, and a theory for its onset is formulated. The growth of the\ncorrugation is governed by the competition between gravitational and bending\n(shearing) forces and is exhibited for a range of densities, stiffnesses\n(viscosities), and sizes -- a result which arises less from dynamics than from\ngeometry, suggesting a wide validity. A quantitative expression for the number\nof ripples is presented, together with experimental results which are in\nagreement with the theoretical predictions."
    },
    {
        "anchor": "Free energy of the edge of an open lipid bilayer based on the\n  interactions of its constituent molecules: Lipid-bilayers are the fundamental constituents of the walls of most living\ncells and lipid vesicles, giving them shape and compartment. The formation and\ngrowing of pores in a lipid bilayer have attracted considerable attention from\nan energetic point of view in recent years. Such pores permit targeted delivery\nof drugs and genes to the cell, and regulate the concentration of various\nmolecules within the cell. The formation of such pores is caused by various\nreasons such as changes in cell environment, mechanical stress or thermal\nfluctuations. Understanding the energy and elastic behaviour of a lipid-bilayer\nedge is crucial for controlling the formation and growth of such pores. In the\npresent work, the interactions in the molecular level are used to obtain the\nfree energy of the edge of an open lipid bilayer. The resulted free-energy\ndensity includes terms associated with flexural and torsional energies of the\nedge, in addition to a line-tension contribution. The line tension, elastic\nmoduli, and spontaneous normal and geodesic curvatures of the edge are obtained\nas functions of molecular distribution, molecular dimensions, cutoff distance,\nand the interaction strength. These parameters are further analyzed by\nimplementing a soft-core interaction potential in the microphysical model. The\ndependence of the elastic free-energy of the edge to the size of the pore is\nreinvestigated through an illustrative example, and the results are found to be\nin agreement with the previous observations.",
        "positive": "Diffusion in active magnetic colloids: Properties of active colloids of circle swimmers are reviewed. As an\nparticular example of active magnetic colloids the magnetotactic bacteria under\nthe action of a rotating magnetic field is considered. The relation for a\ndiffusion coefficient due to the random switching of the direction of rotation\nof their rotary motors is derived on the basis of the master equation. The\nobtained relation is confirmed by the direct numerical simulation of random\ntrajectory of a magnetotactic bacterium under the action of the Poisson type\ninternal noise due to the random switching of rotary motors. The results\nobtained are in qualitative and quantitative agreement with the available\nexperimental results and allows one to determine the characteristic time\nbetween the switching events of a rotary motor of the bacterium."
    },
    {
        "anchor": "Evidence of natural isotopic distribution from single-molecule SERS: We report on the observation of the natural isotopic spread of carbon from\nsingle-molecule Surface Enhanced Raman Spectroscopy (SM-SERS). By choosing a\ndye molecule with a very localized Raman active vibration in a cyano bond\n(C$\\equiv$N triple bond), we observe (in a SERS colloidal liquid) a small\nfraction of SM-SERS events where the frequency of the cyano mode is softened\nand in agreement with the effect of substituting $^{12}$C by the next most\nabundant $^{13}$C isotope. This example adds another demonstration of single\nmolecule sensitivity in SERS through isotopic editing which is done, in this\ncase, not by artificial isotopic editing but rather by nature itself. It also\nhighlights SERS as a unique spectroscopic tool, capable of detecting an\nisotopic change in one atom of a single molecule.",
        "positive": "Dimers of ultracold two-component Fermi gases on magnetic-field Feshbach\n  resonance: At the location of a magnetic-field Feshbach resonance, a mixture gas of\nfermionic atoms and dimers of fermionic atom pairs is investigated in the\nunitarity limit where the absolute value of the scattering length is much\nlarger than the mean distance between atoms. The dynamic equilibrium of the\nmixture gases is characterized by the minimum of the Gibbs free energy. For the\nfermionic atoms and dimers with divergent scattering length, it is found that\nthe fraction of the dimers based on a very simple theory agrees with the high\nfraction of zero-momentum molecules observed in a recent experiment (M. W.\nZwierlein et al, Phys. Rev. Lett. 92, 120403 (2004)). The dimeric gas can be\nalso used to interpret the frequency of the radial breathing mode observed in\nthe experiment by J. Kinast et al (Phys. Rev. Lett. 92, 150402 (2004))."
    },
    {
        "anchor": "Anharmonicity and quasi-localization of the excess low-frequency\n  vibrations in jammed solids: We compare the harmonic and anharmonic properties of the vibrational modes in\n3-dimensional jammed packings of frictionless spheres interacting via\nrepulsive, finite range potentials. A crossover frequency is apparent in the\ndensity of states, the diffusivity and the participation ratio of the modes. At\nthis frequency, which shifts to zero at the jamming threshold, the vibrational\nmodes have a very small participation ratio implying that the modes are\nquasi-localized. The most anharmonic modes occur at low frequency which is\nopposite to what is normally found in crystals. The lowest frequency modes have\nthe strongest response to the pressure and the lowest energy barriers to\nmechanical failure.",
        "positive": "Tomographic femtosecond X-ray diffractive imaging: A method is proposed for obtaining three simultaneous projections of a target\nfrom a single radiation pulse, which also allows the relative orientation of\nsuccessive targets to be determined. The method has application to femtosecond\nX-ray diffraction, and does not require solution of the phase problem. We show\nthat the principle axes of a compact charge-density distribution can be\nobtained from projections of its autocorrelation function, which is directly\naccessible in diffraction experiments. The results may have more general\napplication to time resolved tomographic pump-probe experiments and time-series\nimaging."
    },
    {
        "anchor": "The sinking dynamics and splitting of a granular droplet: Recent experimental results have shown that vibro-fluidized, binary granular\nmaterials exhibit Rayleigh-Taylor-like instabilities that manifest themselves\nin rising plumes, rising bubbles and the sinking and splitting of granular\ndroplets. This work explores the physics behind the splitting of a granular\ndroplet that is composed of smaller and denser particles in a bed of larger and\nlighter particles. During its sinking motion, a granular droplet undergoes a\nseries of binary splits resembling the fragmentation of a liquid droplet\nfalling in a miscible fluid. However, different physical mechanisms cause a\ngranular droplet to split. By applying particle-image-velocimetry and numerical\nsimulations, we demonstrate that the droplet of high-density particles causes\nthe formation of an immobilized zone underneath the droplet. This zone\nobstructs the downwards motion of the droplet and causes the droplet to spread\nand ultimately to split. The resulting fragments sink at inclined trajectories\naround the immobilized zone until another splitting event is initiated. The\noccurrence of consecutive splitting events is explained by the re-formation of\nan immobilized zone underneath the droplet fragments. Our investigations\nidentified three requirements for a granular droplet to split: 1) frictional\ninter-particle contacts, 2) a higher density of the particles composing the\ngranular droplet compared to the bulk particles and 3) and a minimal granular\ndroplet diameter.",
        "positive": "Periodic Orbits of Active Particles induced by Hydrodynamic Monopoles: Terrestrial experiments on active particles, such as Volvox, involve\ngravitational forces, torques and accompanying monopolar fluid flows. Taking\nthese into account, we analyse the dynamics of a pair of self-propelling,\nself-spinning active particles between widely separated parallel planes.\nNeglecting flow reflected by the planes, the dynamics of orientation and\nhorizontal separation is symplectic, with a Hamiltonian exactly determining\nlimit cycle oscillations. Near the bottom plane, gravitational torque damps and\nreflected flow excites this oscillator, sustaining a second limit cycle that\ncan be perturbatively related to the first. Our work provides a theory for\ndancing Volvox and highlights the importance of monopolar flow in active\nmatter."
    },
    {
        "anchor": "Critical Casimir forces steered by patterned substrates: Among the various kinds of effective forces in soft matter, the spatial range\nand the direction of the so-called critical Casimir force - which is generated\nby the enhanced thermal fluctuations close to a continuous phase transition -\ncan be controlled and reversibly modified to an uncommonly large extent. In\nparticular, minute temperature changes of the fluid solvent, which provides the\nnear-critical thermal fluctuations, lead to a significant change of the range\nand strength of the effective interaction among the solute particles. This\nfeature allows one to control, e.g., the aggregation of colloidal dispersions\nor the spatial distribution of colloids in the presence of chemically or\ntopographically patterned substrates. The spatial direction of the effective\nforce acting on a solute particle depends only on the surface properties of the\nimmersed particles and can be spatially modulated by suitably patterned\nsurfaces. These critical Casimir forces are largely independent of the specific\nmaterials properties of both the solvent and the confining surfaces. This\ncharacteristic universality of critical phenomena allows systematic and\nquantitative theoretical studies of the critical Casimir forces in terms of\nsuitable representative and simplified models. Here we highlight recent\ntheoretical and experimental advances concerning critical Casimir forces with a\nparticular emphasis on the numerous possibilities of controlling these forces\nby substrate patterns.",
        "positive": "Uniaxial extensional viscosity of semidilute DNA solutions: The extensional rheology of polymeric liquids has been extensively examined\nthrough experiments and theoretical predictions. However, a systematic study of\nthe extensional rheology of polymer solutions in the semidilute regime, in\nterms of examining the effects of concentration and molecular weight, has not\nbeen carried out so far. Prior studies of the shear rheology of semidilute\npolymer solutions have demonstrated that their behaviour is distinctively\ndifferent from that observed in the dilute and concentrated regimes. This\ndifference in behaviour is anticipated to be even more pronounced in\nextensional flows. In this work, the extensional rheology of linear,\ndouble-stranded DNA molecules, spanning an order of magnitude of molecular\nweights (25 to 289 kilobasepairs) and concentrations (0.03 to 0.3 mg/ml), has\nbeen investigated. DNA solutions are now used routinely as model polymeric\nsystems due to their near-perfect monodispersity. Measurements have been\ncarried out with a filament stretching rheometer since it is the most reliable\nmethod for obtaining an estimate of the elongational stress growth of a polymer\nsolution. Transient and steady-state uniaxial extensional viscosities of DNA\ndissolved in a solvent under excess salt conditions, with a high concentration\nof sucrose in order to achieve a sufficiently high solvent viscosity, have been\ndetermined in the semidilute regime at room temperature. The dependence of the\nsteady state uniaxial extensional viscosity on molecular weight, concentration\nand extension rate is measured with a view to determining if data collapse can\nbe observed with an appropriate choice of variables. Steady state shear\nviscosity measurements suggest that sucrose-DNA interactions might play a role\nin determining the observed rheological behaviour of semidilute DNA solutions\nwith sucrose as a component in the solvent."
    },
    {
        "anchor": "Shear Melting and Recovery of Crosslinkable Cellulose\n  Nanocrystal-Polymer Gels: Cellulose nanocrystals (CNC) are naturally-derived nanostructures of growing\nimportance for the production of composites having attractive mechanical\nproperties, and offer improved sustainability over purely petroleum-based\nalternatives. Fabrication of CNC composites typically involves extrusion of CNC\nsuspensions and gels in a variety of solvents, in the presence of additives\nsuch as polymers and curing agents. However, most studies so far have focused\non aqueous CNC gels, yet the behavior of CNC-polymer gels in organic solvents\nis important to their wider processability. Here, we study the rheological\nbehavior of composite polymer-CNC gels in dimethylformamide, which include\nadditives for both UV and thermal crosslinking. Using rheometry coupled with\nin-situ infrared spectroscopy, we show that under external shear, CNC-polymer\ngels display progressive and irreversible failure of the hydrogen bond network\nthat is responsible for their pronounced elastic properties. In the absence of\ncross-linking additives, the polymer-CNC gels show negligible recovery upon\ncessation of flow, while the presence of additives allows the gels to recover\nvia van der Waals interactions. By exploring a broad range of shear history and\nCNC concentrations, we construct master curves for the temporal evolution of\nthe viscoelastic properties of the polymer-CNC gels, illustrating universality\nof the observed dynamics with respect to gel composition and flow conditions.\nWe therefore find that polymer-CNC composite gels display a number of the\ndistinctive features of colloidal glasses and, strikingly, that their response\nto the flow conditions encountered during processing can be tuned by chemical\nadditives. These findings have implications for processing of dense CNC-polymer\ncomposites in solvent casting, 3D printing, and other manufacturing techniques.",
        "positive": "Harnessing confinement and driving to tune active particle dynamics: A distinguishing feature of active particles is the nature of the\nnon-equilibrium noise driving their dynamics. Control of these noise properties\nis, therefore, of both fundamental and applied interest. We demonstrate\nemergent tuning of the active noise of a granular self-propelled particle by\nconfining it to a quasi one-dimensional channel. We find that this particle,\nmoving like an active Brownian particle (ABP) in two-dimensions, displays\nrun-and-tumble (RTP) characteristics in confinement. We show that the dynamics\nof the relative orientation co-ordinate of the particle maps to that of a\nBrownian particle in a periodic potential subject to a constant force, in\nanalogy to the dynamics of a molecular motor. This mapping captures the\nessential statistical characteristics of the one-dimensional RTP motion.\nSpecifically, our theoretical analysis is in agreement with the empirical\ndistributions of the relative orientation co-ordinate and the run-times\n(tumble-rates) of the particle. Finally, we explicitly control these emergent\nrun-and-tumble like noise parameters by external driving. Altogether, our work\nillustrates geometry-induced tuning of the active dynamics of self-propelled\nunits thus suggesting an independent route to harness their internal dynamics."
    },
    {
        "anchor": "Time-scale coupling in hydrogen- and van der Waals-bonded liquids: The coupling behavior of time scales of structural relaxation is investigated\non the basis of five different response functions for 1,2,6-hexanetriol, a\nhydrogen-bonded liquid with a minor secondary contribution, and\n2,6,10,15,19,23-hexamethyl-tetracosane (squalane), a van der Waals bonded\nliquid with a prominent secondary relaxation process. Time scales of structural\nrelaxation are derived as inverse peak frequencies for each investigated\nresponse function. For 1,2,6-hexanetriol, the time-scale indices are\ntemperature-independent, while a decoupling of time scales is observed for\nsqualane in accordance with literature. An alternative evaluation approach is\nmade on the squalane data, extracting time scales from the terminal relaxation\nmode instead of the peak position, and in this case temperature-independent\ncoupling is also found for squalane, despite its strong secondary relaxation\ncontribution. Interestingly, the very same ordering of\nresponse-function-specific time scales is observed for these two liquids, which\nis also consistent with the observation made for simple van der Waals bonded\nliquids reported previously [Jakobsen \\textit{et al.}, J. Chem. Phys.\n\\textbf{136}, 081102 (2012)]. This time-scale ordering is based on the\nfollowing response functions, from fast to slow dynamics: shear modulus, bulk\nmodulus, dielectric permittivity, longitudinal thermal expansivity coefficient,\nand longitudinal specific heat. These findings indicate a general relation\nbetween the time scales of different response functions and, as inter-molecuar\ninteractions apparently play a subordinate role, suggest a rather generic\nnature of the process of structural relaxation.",
        "positive": "Bending elasticity of macromolecules: analytic predictions from the\n  wormlike chain model: We present a study of the bend angle distribution of semiflexible polymers of\nshort and intermediate lengths within the wormlike chain model. This enables us\nto calculate the elastic response of a stiff molecule to a bending moment. Our\nresults go beyond the Hookean regime and explore the nonlinear elastic\nbehaviour of a single molecule. We present analytical formulae for the bend\nangle distribution and for the moment-angle relation. Our analytical study is\ncompared against numerical Monte Carlo simulations. The functional forms\nderived here can be applied to fluorescence microscopic studies on actin and\nDNA. Our results are relevant to recent studies in \"kinks\" and cyclization in\nshort and intermediate length DNA strands."
    },
    {
        "anchor": "Drag effect and topological complexes in strongly interacting\n  two-component lattice superfluids: The mutual drag in strongly interacting two-component superfluids in optical\nlattices is discussed. Two competing drag mechanisms are the vacancy-assisted\nmotion and proximity to the quasi-molecular state, in which an integer number\n$q$ of atoms (or holes) of one component might be bound to one atom (or hole)\nof the other component. Then the lowest energy topological excitation (vortex\nor persistent current) becomes a composite object consisting of $q$ circulation\nquanta of one component and one circulation of the other. In the SQUID-type\ngeometry, the value of $q$ can become fractional. These topological complexes\ncan be detected by absorptive imaging. We present both the mean field and Monte\nCarlo results. The drag effects in optical lattices are drastically different\nfrom the Galilean invariant Andreev-Bashkin effect in liquid helium.",
        "positive": "Equilibrium calculation of transport coefficients for a fluid-particle\n  model: A recently introduced particle-based model for fluid flow, called Stochastic\nRotation Dynamics, can be made Galilean invariant by introducing a random shift\nof the computational grid before collisions. In this paper, it is shown how the\nGreen-Kubo relations derived previously can be resummed to obtain exact\nexpressions for the collisional contributions to the transport coefficients. It\nis also shown that the collisional contribution to the microscopic stress\ntensor is not symmetric, and that this leads to an additional viscosity. The\nresulting identification of the transport coefficients for the hydrodynamic\nmodes is discussed in detail, and it is shown that this does not impose\nrestrictions on the applicability of the model. The collisional contribution to\nthe thermal conductivity, which becomes important for small mean free path and\nsmall average particle number per cell, is also derived."
    },
    {
        "anchor": "Nonequilibrium mode-coupling theory for uniformly sheared systems: We develop a nonequilibrium mode-coupling theory for uniformly sheared\nsystems starting from microscopic, thermostatted SLLOD equations of motion. Our\ntheory aims at describing stationary-state properties including rheological\nones of sheared systems, and this is accomplished via two steps. Firstly, a set\nof self-consistent equations is formulated based on the projection-operator\nformalism and on the mode-coupling approach for the transient density\ncorrelators which measure the correlations between the density fluctuations in\nthe initial equilibrium state and the ones at later times after the shearing\nforce is turned on. The transient time-correlation function formalism is then\nused which, combined with the mode-coupling approximation, expresses\nstationary-state properties in terms of the transient density correlators. A\ndetailed comparison of our theory is also presented with the related\nmode-coupling theory which is based on the Smoluchowski equation for Brownian\nparticles under stationary shearing.",
        "positive": "Wettability of reentrant surfaces: a global energy approach: In this work we consider two possible wetting states for a droplet when\nplaced on a substrate: the Fakir configuration of a Cassie-Baxter (CB) state\nwith a droplet residing on top of roughness grooves and the Wenzel (W) state\ncharacterized by the homogeneous wetting of the surface. We extend a\ntheoretical model based on the global interfacial energies for both states to\nstudy the wetting behavior of simple and double reentrant surfaces. Due to the\nminimization of the energies associated to each wetting state, we predict the\nthermodynamic wetting state of the droplet for a given surface and obtain its\ncontact angle ${\\theta}_C$. We first use this model to find the geometries for\npillared, simple and double reentrant surfaces that most enhances ${\\theta}_C$\nand conclude that the repellent behavior of these surfaces is governed by the\nrelation between the height and width of the reentrances. We compare our\nresults with recent experiments and discuss the limitations of this\nthermodynamic approach. To address one of these limitations, we implement Monte\nCarlo simulations of the cellular Potts Model in three dimensions, allowing us\nto investigate the dependency of the wetting state on the initial state of the\ndroplet. We find that when the droplet is initialized in a CB state, it gets\ntrapped in a local minimum and stays in the repellent behavior irrespective of\nthe theoretical prediction. When the initial state is W, simulations show a\ngood agreement with theory for pillared surfaces, but for reentrant surfaces\nthe agreement only happens in few cases: for most simulated geometries the\ncontact angle reached by the droplet in simulations is higher than ${\\theta}_C$\npredicted by the model. Moreover, we find that the contact angle of the\nsimulated droplet is higher when placed on the reentrant surfaces than for a\npillared surfaces with the same height, width and pillar distance."
    },
    {
        "anchor": "Controlling biomolecular condensates via chemical reactions: Biomolecular condensates are small droplets forming spontaneously in\nbiological cells via phase separation. They play a role in many cellular\nprocesses, but it is unclear how cells control them. Cellular regulation often\nrelies on post-translational modifications of proteins. For biomolecular\ncondensates, such chemical modifications could alter the molecular interaction\nof key condensate components. We here test this idea using a theoretical model\nbased on non-equilibrium thermodynamics. In particular, we describe the\nchemical reactions using transition-state theory, which accounts for the\nnon-ideality of phase separation. We identify that fast control, like in cell\nsignaling, is only possible when external energy input drives the reaction out\nof equilibrium. If this reaction differs inside and outside the droplet, it is\neven possible to control droplet sizes. Such an imbalance in the reaction could\nbe created by enzymes localizing to the droplet. Since this situation is\ntypical inside cells, we speculate that our proposed mechanism is used to\nstabilize multiple droplets with independently controlled size and count. Our\nmodel provides a novel and thermodynamically consistent framework for\ndescribing droplets subject to non-equilibrium chemical reactions.",
        "positive": "Time-averaged approach to the dewetting problem at evaporation: Dewetting of liquid films on solid surfaces in the presence of evaporation is\na common phenomenon and has been studied by many researchers. The previous\nnumerical approach has revealed that evaporation accelerates the dewetting\nspeed of the triple contact line and established correlations between the\ndewetting speed and the surface wettability and superheating. However, such a\nnumerical calculation is time- and resource-consuming. ,We examine dewetting\nphysics and propose a time-averaged approach based on the multiscale theory.\nThe new approach averages the dewetting process over time and consists of only\nseveral algebraic equations, making the problem easier to solve. It can produce\ntime-averaged values of essential quantities, such as the dewetting speed and\ncontact angle as a function of superheating, which agrees with the previous\nnumerical results. This simple approach is valuable for many applications, such\nas modeling pulsating heat pipes and describing the microlayer dynamics under\ngrowing vapor bubbles in nucleate boiling."
    },
    {
        "anchor": "Iterative Reconstruction of Memory Kernels: In recent years, it has become increasingly popular to construct\ncoarse-grained models with non-Markovian dynamics to account for an incomplete\nseparation of time scales. One challenge of a systematic coarse-graining\nprocedure is the extraction of the dynamical properties, namely, the memory\nkernel, from equilibrium all-atom simulations. In this article, we propose an\niterative method for memory reconstruction from dynamical correlation\nfunctions. Compared to previously proposed noniterative techniques, it ensures\nby construction that the target correlation functions of the original\nfine-grained systems are reproduced accurately by the coarse-grained system,\nregardless of time step and discretization effects. Furthermore, we also\npropose a new numerical integrator for generalized Langevin equations that is\nsignificantly more accurate than the more commonly used generalization of the\nvelocity Verlet integrator. We demonstrate the performance of the\nabove-described methods using the example of backflow-induced memory in the\nBrownian diffusion of a single colloid. For this system, we are able to\nreconstruct realistic coarse-grained dynamics with time steps about 200 times\nlarger than those used in the original molecular dynamics simulations.",
        "positive": "Hard biaxial ellipsoids revisited: numerical results: Monte Carlo simulations are performed for hard ellipsoids for a number of\nvalues of its semi-axes in the range $c/a \\in \\{0.1,10\\}$. The isotropic phase\nresults are compared to the Vega equation of state [Mol. Phys. {\\bf 92} (1997)\n651-665]. The position of the isotropic-nematic transition is also evaluated.\nThe biaxial phase is seen to form only after the previous formation of a\ndiscotic phase."
    },
    {
        "anchor": "Quantum spin liquid in antiferromagnetic chain S=1/2 with Acoustic\n  Phonons: A spin and phonon excitations spectrum are studied using quantum Monte Carlo\nmethod in antiferromagnetic chain with spins $S=1/2$ coupled nonadiabaticity\nwith acoustic phonons . It is found the critical coupling exists to open gap in\nthe triplet excitation spectrum for any phonon velocity. The phase boundaries\nof delocalized phonons and propagated the bound states of magnon and a phonon\nare calculated. It is shown that the spherical symmetry of the spin-spin\ncorrelation functions is broken . The magnetic and optical properties $CuGeO_3$\nare explained without using spin-Peierls transition.",
        "positive": "An improved integration scheme for Mode-coupling-theory equations: Within the mode-coupling theory (MCT) of the glass transition, we reconsider\nthe numerical schemes to evaluate the MCT functional. Here we propose\nnonuniform discretizations of the wave number, in contrast to the standard\nequidistant grid, in order to decrease the number of grid points without losing\naccuracy. We discuss in detail how the integration scheme on the new grids has\nto be modified from standard Riemann integration. We benchmark our approach by\nsolving the MCT equations numerically for mono-disperse hard disks and hard\nspheres and by computing the critical packing fraction and the nonergodicity\nparameters. Our results show that significant improvements in performance can\nbe obtained by employing a nonuniform grid."
    },
    {
        "anchor": "Global topology of contact force networks: new insight into shear\n  thickening suspensions: Highly concentrated or 'dense\" particle suspensions can undergo a sharp\nincrease in viscosity, or shear thickening, under applies stress. Understanding\nthe fundamental features leading to such rheological changes in dense\nsuspensions is crucial to optimize flow conditions or to design flow modifiers\nfor slurry processing. While local changes to the particle environment under an\napplied shear can be related to changes in viscosity, there is a broader need\nto connect the shear thickening transition to the fundamental organization of\nparticle-interaction forces which lead to long-range organization. In\nparticular, at a high volume fraction of particles, recent evidence indicates\nfrictional forces between contacting particles is of importance. Herein, the\nnetwork of frictional contact forces is analyzed within simulated\ntwo-dimensional shear thickening suspensions. Two topological metrics are\nstudied to characterize the response of the contact force network (CFN) under\nvarying applied shear stress. The metrics, geodesic index and the void\nparameter, reflect complementary aspects of the CFN: one is the connectedness\nof the contact network and the second is the distribution of spatial areas\ndevoid of particle-particle contacts. Considered in relation to the variation\nof the viscosity, the topological metrics show that the network grows\nhomogeneously at large scales but with many local regions devoid of contacts,\nindicating clearly the role of stress chain growth in causing the large change\nin the rheological response at the shear thickening transition.",
        "positive": "Confinement-driven translocation of a flexible polymer: We consider the escape of a flexible, self-avoiding polymer chain out of a\nconfined geometry. By means of simulations, we demonstrate that the\ntranslocation time can be described by a simple scaling law that exhibits a\nnonlinear dependence on the degree of polymerization and that is sensitive to\nthe nature of the confining geometry. These results contradict earlier\npredictions but are in agreement with recently confirmed geometry-dependent\nexpressions for the free energy of confinement."
    },
    {
        "anchor": "Role of dimensions in first passage of a diffusing particle under\n  stochastic resetting and attractive bias: Recent studies in one dimension have revealed that the temporal advantage\nrendered by stochastic resetting to diffusing particles in attaining first\npassage, may be annulled by a sufficiently strong attractive potential. We\nextend the results to higher dimensions. For a diffusing particle in an\nattractive potential $V({R})=k {R}^n$, in general $d$ dimensions, we study the\ncritical strength $k = k_c$ above which resetting becomes disadvantageous. The\npoint of continuous transition may be exactly found even in cases where the\nproblem with resetting is not solvable, provided the first two moments of the\nproblem without resetting are known. We find the dimensionless critical\nstrength $\\kappa_{c,n}(k_c)$ exactly when $d/n$ and $2/n$ take positive\nintegral values. Also for the limiting case of a box potential (representing $n\n\\to \\infty$), and the special case of a logarithmic potential $k\n\\ln\\big(\\frac{R}{a}\\big)$, we find the corresponding transition points\n$\\kappa_{c,\\infty}$ and $\\kappa_{c,l}$ exactly for any dimension $d$. The\nasymptotic forms of the critical strengths at large dimensions $d$ are\ninteresting. We show that for the power law potential, for any $n \\in\n(0,\\infty)$, the dimensionless critical strength $\\kappa_{c,n} \\sim\nd^{\\frac{1}{n}}$ at large $d$. For the box potential, asymptotically,\n$\\kappa_{c,\\infty} \\sim (1 - \\ln(\\frac{d}{2})/d)$, while for the logarithmic\npotential, $\\kappa_{c,l} \\sim d$.",
        "positive": "Mediation of hydrogen-bond coupling interactions by programmable heating\n  and salting: We show that programmable heating and salting share the same effect on the\nfrequency shift of the O:H and the H-O stretching phonons of the O:H-O hydrogen\nbond, which revealed that both heating and salting lengthens and softens the\nO:H bond and shortens and stiffens the H-O bond due to the weakening of the\nCoulomb repulsion between electron pairs of adjacent oxygen atoms.\nUnderstanding provides possible mechanism for the Hofmeister series and the\ndetergent effect on cloth cleaning."
    },
    {
        "anchor": "Heterogeneous Diffusion in Highly Supercooled Liquids: The diffusivity of tagged particles is demonstrated to be very heterogeneous\non time scales comparable to or shorter than the $\\alpha$ relaxation time\n$\\tau_{\\alpha}$ ($\\cong$ the stress relaxation time) in a highly supercooled\nliquid via 3D molecular dynamics simulation. The particle motions in the\nrelatively active regions dominantly contribute to the mean square\ndisplacement, giving rise to a diffusion constant systematically larger than\nthe Einstein-Stokes value. The van Hove self-correlation function $G_s(r,t)$ is\nshown to have a long distance tail which can be scaled in terms of $r/t^{1/2}$\nfor $t \\ls 3\\tau_{\\alpha}$. Its presence indicates heterogeneous diffusion in\nthe active regions. However, the diffusion process eventually becomes\nhomogeneous on time scales longer than the life time of the heterogeneity\nstructure ($\\sim 3 \\tau_{\\alpha}$).",
        "positive": "Correlation between ordering and shear thinning in confined liquids: Despite the extensive research that has been conducted for decades on the\nbehavior of confined liquids, detailed knowledge of this phenomenon,\nparticularly in the mixed/boundary lubrication regime, remains limited. This\ncan be attributed to several factors including the difficulty of direct\nexperimental observations of the behavior of lubricant molecules under\nnon-equilibrium conditions, the high computational cost of molecular\nsimulations to reach steady state, and the low signal-to-noise ratio at\nextremely low shear rates corresponding to actual operating conditions. To this\nend, we studied the correlation between the structure formation and shear\nviscosity of octamethylcyclotetrasiloxane confined between two mica surfaces in\na mixed/boundary lubrication regime. Three different surface separations\ncorresponding to two-, three-, and five-layered structures were considered to\nanalyze the effect of confinement. The orientational distributions with one\nspecific peak for $n=2$ and two distributions, including a parallel orientation\nwith the surface normal for $n>2$, were observed at rest. The confined liquids\nexhibited a distinct shear-thinning behavior independent of surface separations\nfor a relatively low sliding velocity, $V_{\\rm x}\\lesssim 10^{-1}\\,{\\rm m/s}$.\nHowever, the shear viscosities at $V_{\\rm x}\\lesssim 10^{-1}\\,{\\rm m/s}$\ndepended on the number of layered structures. Newtonian behavior was observed\nwith a further increase in the sliding velocity. Furthermore, we found a strong\ncorrelation between the degree of molecular orientation and the shear viscosity\nof the confined liquids. The magnitude of the shear viscosity of the confined\nliquids can primarily be determined by the degree of molecular orientation, and\nshear-thinning originates from the vanishing of specific orientational\ndistributions with increasing sliding velocity."
    },
    {
        "anchor": "Collapsing granular suspensions: A 2D contact dynamics model is proposed as a microscopic description of a\ncollapsing suspension/soil to capture the essential physical processes\nunderlying the dynamics of generation and collapse of the system. Our physical\nmodel is compared with real data obtained from in situ measurements performed\nwith a natural collapsing/suspension soil. We show that the shear strength\nbehavior of our collapsing suspension/soil model is very similar to the\nbehavior of this collapsing suspension soil, for both the unperturbed and the\nperturbed phases of the material.",
        "positive": "On the validity of some equilibrium models for thermodiffusion: When applied to binary solutions, thermal gradients lead to the generation of\nconcentration-gradients and thus to inhomogeneous systems. While being known\nfor more than 150 years, the molecular origins for this phenomenon are still\ndebated, and there is no consensus on the underlying physical models or\ntheories that could explain the amplitude of the concentration gradient in\nresponse to a given temperature gradients. Notably, there have been some\nattempts to relate this non-equilibrium, steady-state manifestation, to\nequilibrium properties of these solutions, for example, to the temperature\ndependence of the self-diffusion coefficient or to the solvation free-energies\nof each of their components. Here, we use molecular dynamics simulations on\ndilute solutions containing molecular size solutes, both in a thermophoretic\nsetting as well as under equilibrium conditions, to test the validity of such\nmodels. We show that these approaches are inadequate and lead to completely\nuncorrelated estimates as compared to those based on the out-of-equilibrium\nmeasurements. Crucially, they fail to explain the strong mass-dependence (to\nwhich thermodynamics or single particle diffusion are insensitive) observed in\nthe simulations and measured in the experiments. However, our results suggest\nan interesting correlation between the amplitude of the short-time molecular\nmotion and that of the concentration-gradient that would deserve future\ninvestigations."
    },
    {
        "anchor": "Formation and mechanics of fire ant rafts as an active self-healing\n  membrane: The unique ability of fire ants to form a raft to survive flooding rain has\nenchanted biologists as well as researchers in other disciplines. It has been\nestablished during the last decade that an aggregation of fire ants exhibits\nviscoelasticity with respect to external compression and shearing among\nnumerous unusual mechanical properties. In addition to clarifying that the\nCheerios effect is neither sufficient nor essential for the ant raft, we\nperform the force-displacement and creep experiments on the ant raft and\nconcentrate on unearthing properties that derive from the unique combination of\nself-healing and activeness of its constituent. Varying pull speed results in\ndistinct mechanical responses and fracture patterns, characteristic of ductile\nand brittle material. By image processing, we count the number of ants that\nactively participate in the stress-strain relation and determine their\norientation to map out the force chain. The latter information reveals that the\npull force expedites the alignment of fire ants, in analogy to the effect of an\nelectric field on liquid crystal polymers. In addition, the raft can be\ntailored not to transversely deform in response to the axial strain. Without\nresorting to specific geometry structures, this property of zero Poisson's\nratio is enabled by the active recruitment of ants from the top to bottom layer\nto keep the raft from disintegrating. Furthermore, effective Young's modulus\ncan also be customized and is proportion to either the raft length or its\ninverse, depending on whether the raft is in the elastic or plastic region.",
        "positive": "Role of the glassy dynamics and thermal mixing in the dynamic nuclear\n  polarization and relaxation mechanisms of pyruvic acid: The temperature dependence of $^1$H and $^{13}$C nuclear spin-lattice\nrelaxation rate $1/T_1$ has been studied in the 1.6 K - 4.2 K temperature range\nin pure pyruvic acid and in pyruvic acid containing trityl radicals at a\nconcentration of 15 mM. The temperature dependence of $1/T_1$ is found to\nfollow a quadratic power law for both nuclei in the two samples. Remarkably the\nsame temperature dependence is displayed also by the electron spin-lattice\nrelaxation rate $1/T_{1e}$ in the sample containing radicals. These results are\nexplained by considering the effect of the structural dynamics on the\nrelaxation rates in pyruvic acid. Dynamic nuclear polarization experiments show\nthat below 4 K the $^{13}$C build up rate scales with $1/T_{\\text{1e}}$, in\nanalogy to $^{13}$C $1/T_1$ and consistently with a thermal mixing scenario\nwhere all the electrons are collectively involved in the dynamic nuclear\npolarization process and the nuclear spin reservoir is in good thermal contact\nwith the electron spin system."
    },
    {
        "anchor": "Model-free approach to the interpretation of restricted and anisotropic\n  self-diffusion in magnetic resonance of biological tissues: Magnetic resonance imaging (MRI) is the method of choice for noninvasive\nstudies of micrometer-scale structures in biological tissues via their effects\non the time/frequency-dependent (\"restricted\") and anisotropic self-diffusion\nof water. Traditional MRI relies on pulsed magnetic field gradients to encode\nthe signal with information about translational motion in the direction of the\ngradient, which convolves fundamentally different aspects-such as bulk\ndiffusivity, restriction, anisotropy, and flow-into a single effective\nobservable lacking specificity to distinguish between biologically plausible\nmicrostructural scenarios. To overcome this limitation, we introduce a formal\nanalogy between measuring rotational correlation functions and interaction\ntensor anisotropies in nuclear magnetic resonance (NMR) spectroscopy and\ninvestigating translational motion in MRI, which we utilize to convert data\nacquisition and analysis strategies from NMR of rotational dynamics in\nmacromolecules to MRI of diffusion in biological tissues, yielding\nmodel-independent quantitative metrics reporting on relevant microstructural\nproperties with unprecedented specificity. Our model-free approach advances the\nstate-of-the-art in microstructural MRI, thereby enabling new applications to\ncomplex multi-component tissues prevalent in both tumors and healthy brain.",
        "positive": "Revisiting Imidazolium Based Ionic Liquids: Effect of the Conformation\n  Bias of the [NTf$_{2}$] Anion Studied By Molecular Dynamics Simulations: We study ionic liquids composed 1-alkyl-3-methylimidazolium cations and\nbis(trifluoromethyl-sulfonyl)imide anions ([C$_n$MIm][NTf$_2$]) with varying\nchain-length $n\\!=\\!2, 4, 6, 8$ by using molecular dynamics simulations. We\nshow that a reparametrization of the dihedral potentials as well as charges of\nthe [NTf$_2$] anion leads to an improvment of the force field model introduced\nby K\\\"oddermann {\\em et al.} [ChemPhysChem, \\textbf{8}, 2464 (2007)] (KPL-force\nfield). A crucial advantage of the new parameter set is that the minimum energy\nconformations of the anion ({\\em trans} and {\\em gauche}), as deduced from {\\em\nab initio} calculations and {\\sc Raman} experiments, are now both well\nrepresented by our model. In addition, the results for [C$_n$MIm][NTf$_2$] show\nthat this modification leads to an even better agreement between experiment and\nmolecular dynamics simulation as demonstrated for densities, diffusion\ncoefficients, vaporization enthalpies, reorientational correlation times, and\nviscosities. Even though we focused on a better representation of the anion\nconformation, also the alkyl chain-length dependence of the cation behaves\ncloser to the experiment. We strongly encourage to use the new NGKPL force\nfield for the [NTf$_2$] anion instead of the earlier KPL parameter set for\ncomputer simulations aiming to describe the thermodynamics, dynamics and also\nstructure of imidazolium based ionic liquids."
    },
    {
        "anchor": "Computing with non-orientable defects: nematics, smectics and natural\n  patterns: Defects are a ubiquitous feature of ordered media. They have certain\nuniversal features, independent of the underlying physical system, reflecting\ntheir topological origins. While the topological properties of defects are\nrobust, they appear as `unphysical' singularities, with non-integrable energy\ndensities in coarse-grained macroscopic models. We develop a principled\napproach for enriching coarse-grained theories with enough of the\n`micro-physics' to obtain thermodynamically consistent, well-set models, that\nallow for the investigations of dynamics and interactions of defects in\nextended systems. We also develop associated numerical methods that are\napplicable to computing energy driven behaviors of defects across the\namorphous-soft-crystalline materials spectrum. Our methods can handle order\nparameters that have a head-tail symmetry, i.e. director fields, in systems\nwith a continuous translation symmetry, as in nematic liquid crystals, and in\nsystems where the translation symmetry is broken, as in smectics and convection\npatterns. We illustrate our methods with explicit computations.",
        "positive": "Bidirectional Motion of Droplets on Gradient Liquid Infused Surfaces: We demonstrate spontaneous bidirectional motion of droplets on liquid infused\nsurfaces in the presence of a topographical gradient, in which the droplets can\nmove either toward the denser or the sparser solid fraction area. Our\nanalytical theory explains the origin of this bidirectional motion.\nFurthermore, using both lattice Boltzmann simulations and experiments, we show\nthat the key factor determining the direction of motion is the wettability\ndifference of the droplet on the solid surface and on the lubricant film. The\nbidirectional motion is shown for various combinations of droplets and\nlubricants, as well as for different forms of topographical gradients."
    },
    {
        "anchor": "Universal hydrodynamic mechanisms for crystallization in active\n  colloidal suspensions: The lack of detailed balance in active colloidal suspensions allows\ndissipation to determine stationary states. Here we show that slow viscous flow\nproduced by polar or apolar active colloids near plane walls mediates\nattractive hydrodynamic forces that drive crystallization. Hydrodynamically\nmediated torques tend to destabilize the crystal but stability can be regained\nthrough critical amounts of bottom-heaviness or chiral activity. Numerical\nsimulations show that crystallization is not nucleational, as in equilibrium,\nbut is preceded by a spinodal-like instability. Harmonic excitations of the\nactive crystal relax diffusively but the normal modes are distinct from an\nequilibrium colloidal crystal. The hydrodynamic mechanisms presented here are\nuniversal and rationalize recent experiments on the crystallization of active\ncolloids.",
        "positive": "Shear viscosity of two-dimensional Yukawa systems in liquid state: The shear viscosity of a two-dimensional (2D) liquid was calculated using\nequilibrium molecular dynamics simulations with a Yukawa potential. The shear\nviscosity has a minimum, at a Coulomb coupling parameter of about 17, arising\nfrom the temperature dependence of the kinetic and potential contributions.\nPrevious calculations of 2D viscosity were less extensive, and for a different\npotential. The stress autocorrelation function was found to decay rapidly,\ncontrary to some earlier work. These results are useful for 2D condensed matter\nsystems and are compared to a recent dusty plasma experiment."
    },
    {
        "anchor": "Parameter-free prediction of DNA dynamics in planar extensional flow of\n  semidilute solutions: The dynamics of individual DNA molecules in semidilute solutions undergoing\nplanar extensional flow is simulated using a multi-particle Brownian dynamics\nalgorithm, which incorporates hydrodynamic and excluded volume interactions in\nthe context of a coarse-grained bead-spring chain model for DNA. The successive\nfine-graining protocol [1, 2], in which simulation data acquired for\nbead-spring chains with increasing values of the number of beads $N_b$, is\nextrapolated to the number of Kuhn steps $N_\\text{K}$ in DNA (while keeping key\nphysical parameters invariant), is used to obtain parameter-free predictions\nfor a range of Weissenberg numbers and Hencky strain units. A systematic\ncomparison of simulation predictions is carried out with the experimental\nobservations of [3], who have recently used single molecule techniques to\ninvestigate the dynamics of dilute and semidilute solutions of $\\lambda$-phage\nDNA in planar extensional flow. In particular, they examine the response of\nindividual chains to step-strain deformation followed by cessation of flow,\nthereby capturing both chain stretch and relaxation in a single experiment. The\nsuccessive fine-graining technique is shown to lead to quantitatively accurate\npredictions of the experimental observations in the stretching and relaxation\nphases. Additionally, the transient chain stretch following a step strain\ndeformation is shown to be much smaller in semidilute solutions than in dilute\nsolutions, in agreement with experimental observations.",
        "positive": "The aqueous Triton X-100 - Dodecyltrimethylammonium bromide micellar\n  mixed system. Experimental results and thermodynamic analysis: The micellization process of the aqueous mixed system Triton X-100\n(TX100)-Dodecyltrimethylammonium Bromide (DTAB) was studied with a battery of\nprocedures: surface tension, static and dynamic light scattering and\nion-selective electrodes. Results were also analysed with two thermodynamic\nprocedures. The system shows some changes in its behaviour with changing the\nmole fraction of DTAB, $\\alpha_{DTAB}$, in the whole surfactant mixture. For $\n\\alpha_{DTAB} < 0.40$ micelles are predominantly TX100 with scarce solubilized\nDTA+ ions, and TX100 acts as a nearly ideal solvent. In the range $0.50 <\n\\alpha_{DTAB} < 0.75$ it seems that none of the components acts as a solvent,\nand above $\\alpha_{DTAB} > 0.75$ there are abrupt changes in the size and\nelectrophoretic mobility of micelles. These phenomena have been interpreted in\nthe light of the thermodynamic results and some TX100-ionic surfactant mixtures\nof literature."
    },
    {
        "anchor": "Competing chemical and hydrodynamic interactions in autophoretic\n  colloidal suspensions: At the surfaces of autophoretic colloids, slip velocities arise from local\nchemical gradients that are many-body functions of particle configuration and\nactivity. For rapid chemical diffusion, coupled with slip-induced hydrodynamic\ninteractions, we deduce the chemohydrodynamic forces and torques between\ncolloids. Near a no-slip wall, the forces can be expressed as gradients of a\nnon-equilibrium potential which, by tuning the type of activity, can be varied\nfrom repulsive to attractive. When this potential has a barrier, we find\narrested phase separation with a mean cluster size set by competing chemical\nand hydrodynamic forces. These are controlled in turn by the monopolar and\ndipolar contributions to the active chemical surface fluxes.",
        "positive": "Self-diffusion in plastic flow of amorphous solids: We report on a particle-based numerical study of sheared amorphous solids in\nthe dense slow flow regime. In this framework, deformation and flow are\naccompanied by critical fluctuation patterns associated with the macroscopic\nplastic response and single particle kinematics. The former is commonly\nattributed to the collective slip patterns that relax internal stresses within\nthe bulk material and give rise to an effective mechanical noise governing the\nlatter particle-level process. In this work, the avalanche-type dynamics\nbetween plastic events is shown to have a strong relevance on the\nself-diffusion of tracer particles in the Fickian regime. As a consequence,\nstrong size effects emerge in the effective diffusion coefficient that is\nrationalized in terms of avalanche size distributions and the relevant temporal\noccurrence."
    },
    {
        "anchor": "Lattice Model for water-solute mixtures: A lattice model for the study of mixtures of associating liquids is proposed.\nSolvent and solute are modeled by adapting the associating lattice gas (ALG)\nmodel. The nature of interaction solute/solvent is controlled by tuning the\nenergy interactions between the patches of ALG model. We have studied three set\nof parameters, resulting on, hydrophilic, inert and hydrophobic interactions.\nExtensive Monte Carlo simulations were carried out and the behavior of pure\ncomponents and the excess properties of the mixtures have been studied. The\npure components: water (solvent) and solute, have quite similar phase diagrams,\npresenting: gas, low density liquid, and high density liquid phases. In the\ncase of solute, the regions of coexistence are substantially reduced when\ncompared with both the water and the standard ALG models. A numerical procedure\nhas been developed in order to attain series of results at constant pressure\nfrom simulations of the lattice gas model in the grand canonical ensemble. The\nexcess properties of the mixtures: volume and enthalpy as the function of the\nsolute fraction have been studied for different interaction parameters of the\nmodel. Our model is able to reproduce qualitatively well the excess volume and\nenthalpy for different aqueous solutions. For the hydrophilic case, we show\nthat the model is able to reproduce the excess volume and enthalpy of mixtures\nof small alcohols and amines. The inert case reproduces the behavior of large\nalcohols such as, propanol, butanol and pentanol. For last case (hydrophobic),\nthe excess properties reproduce the behavior of ionic liquids in aqueous\nsolution.",
        "positive": "Distribution of the second virial coefficients of globular proteins: George and Wilson [Acta. Cryst. D 50, 361 (1994)] looked at the distribution\nof values of the second virial coefficient of globular proteins, under the\nconditions at which they crystallise. They found the values to lie within a\nfairly narrow range. We have defined a simple model of a generic globular\nprotein. We then generate a set of proteins by picking values for the\nparameters of the model from a probability distribution. At fixed solubility,\nthis set of proteins is found to have values of the second virial coefficient\nthat fall within a fairly narrow range. The shape of the probability\ndistribution of the second virial coefficient is Gaussian because the second\nvirial coefficient is a sum of contributions from different patches on the\nprotein surface."
    },
    {
        "anchor": "Dewetting of Thin Lubricating Films Underneath Aqueous Drops on Slippery\n  Surfaces: Stability of thin lubricating fluid coated slippery surfaces depends on the\nsurface energy of the underlying solid surface. High energy solid surfaces,\ncoated with thin lubricating oil, lead to the dewetting of the oil films upon\ndepositing aqueous drops on it. The total surface energy, which is due to the\nlong range and short range interactions, also predict the instability of thin\nlubricating films under the given condition. In this article, we present\nexperimental study of dewetting of thin lubricating oil films sandwiched\nbetween hydrophilic solid surface and aqueous drops. Fluorescence imaging of\nlubricant film and wetting behavior of aqueous drops are used for the analysis.\nWe find that the dewetting dynamics and the final pattern depend strongly on\nthe thickness of the lubricating oil film.",
        "positive": "Comment on ``Passage Times for Unbiased Polymer Translocation through a\n  Narrow Pore'': One of the most fundamental quantities associated with polymer translocation\nthrough a nanopore is the translocation time $\\tau$ and its dependence on the\nchain length $N$. Our simulation results based on both the bond fluctuation\nMonte Carlo and Molecular Dynamics methods confirm the original prediction\n$\\tau\\sim N^{2\\nu+1}$, which scales in the same manner as the Rouse relaxation\ntime of the chain except for a larger prefactor, and invalidates other scaling\nclaims."
    },
    {
        "anchor": "Solvation of positive ions in water: The dominant role of water-water\n  interaction: Local polarization effects, induced by mono and divalent positive ions in\nwater, influence (and in turn are influenced by) the large scale structural\nproperties of the solvent. Experiments can only distinguish this process of\ninterplay in a generic qualitative way. Instead, first principles quantum\ncalculations can address the question at both electronic and atomistic scale,\naccounting for electronic polarization as well as geometrical conformations.\nFor this reason we study the extension of the scales' interconnection by means\nof first principle Car-Parrinello molecular dynamics applied to systems of\ndifferent size. In this way we identify the general aspects dominating the\nphysics of the first solvation shell and their connection to the effects\nrelated to the formation of the outer shells and eventually the bulk. We show\nthat while the influence of the ions is extended to the first shell only, the\nwater-water interaction is instead playing a dominant role even within the\nfirst shell independently from the size or the charge of the ion.",
        "positive": "Theory of Liquid Crystal Elastomers: From Polymer Physics to\n  Differential Geometry: In liquid crystal elastomers, the orientational order of liquid crystals is\ncoupled with elastic distortions of crosslinked polymer networks. Previous\ntheoretical research has described these materials through two different\napproaches: a neoclassical theory based on the liquid crystal director and the\ndeformation tensor, and a geometric elasticity theory based on the difference\nbetween the actual metric tensor and a reference metric. Here, we connect those\ntwo approaches using a formalism based on differential geometry. Through this\nconnection, we determine how both the director and the geometry respond to a\nchange of temperature."
    },
    {
        "anchor": "Colloids, polymers, and needles: Demixing phase behavior: We consider a ternary mixture of hard colloidal spheres, ideal polymer\nspheres, and rigid vanishingly thin needles, which model stretched polymers or\ncolloidal rods. For this model we develop a geometry-based density functional\ntheory, apply it to bulk fluid phases, and predict demixing phase behavior. In\nthe case of no polymer-needle interactions, two-phase coexistence between\ncolloid-rich and -poor phases is found. For hard needle-polymer interactions we\npredict rich phase diagrams, exhibiting three-phase coexistence, and reentrant\ndemixing behavior.",
        "positive": "A tangential force model for interactions between bonded colloidal\n  particles: Recently, Pantina and Furst (Phys. Rev. Lett., 94(13), 138301, 2005)\nexperimentally demon- strated that there are tangential forces between bonded\ncolloidal particles and that bonds between colloidal particles are capable of\nsupporting bending moments. We introduce a model to be used in computer\nsimulations that describes these tangential interactions. We show how the model\nparame- ters can be determined from experimental data. Simulations using the\nmodel are able to reproduce the measurement of Pantina and Furst. Application\nof the model to an aggregate with fractal structure leads to more realistic\nbehavior than using classical approaches only."
    },
    {
        "anchor": "The simplest microscopic model of a complex fluid: flow phenomena and\n  constitutive relation: It was shown in [PRL 114, 138301 (2015)] that a remarkably simple dynamical\nmodel exhibits many of the complex flow regimes and non-equilibrium phase\ntransitions characteristic of complex fluids. By removing extraneous detail,\nthis simplest microscopic model of non-Newtonian flow can reveal the universal\nphysics relevant to all complex fluids. Here we present more detailed results\nand a full derivation of the model's compact mean-field constitutive relation,\nwith great potential scope for insights into universality and tractable\nmathematics. By enforcing local conservation of angular momentum, the\none-dimensional (1D) XY-model (originally used for equilibrium magnetic\nsystems) can be driven into various flow regimes, including simple Newtonian\nbehaviour, shear banding, solid-liquid coexistence and slip-plane motion. The\nmodel demonstrates that the phenomenon of shear banding does not rely on\ndetails of tensorial stress fields, but can exist in 1D.",
        "positive": "Phase transition of a single star polymer: a Wang-Landau sampling study: Star polymer is a typical nonlinear macromolecule possessing special\nthermodynamic behaviors for the existence of a jointing point. The\nthermodynamic transitions of a single star polymer are systematically studied\nwith bond fluctuation model using Wang-Landau sampling technique. A new\nanalysis method applying the shape factor is proposed to determine coil-globule\n(CG) and liquid-crystal (LC) transitions, which shows higher efficiency and\nprecision than canonical specific heat function. It is found that the LC\ntransition of star polymer at lower temperature obeys the identical scaling law\nas linear polymer. With the increase of the arm density of star polymer,\nhowever, the CG transition point, corresponding to {\\theta} temperature, shifts\ntowards the LC transition and the reason comes from the high density arms of\nstar polymer, which requires the lower temperature for attracting force to\novercome the volume excluding effects of chain. This work clearly demonstrates\nthat the distinction of linear and star polymers in structures only affects CG\ntransition and has no influence on LC transition."
    },
    {
        "anchor": "Nonlinear optical properties of a channel waveguide produced with\n  crosslinkable ferroelectric liquid crystals: A binary mixture of ferroelectric liquid crystals (FLCs) was used for the\ndesign of a channel waveguide. The FLCs possess two important functionalities:\na chromophore with a high hyperpolarizability $\\beta$ and photoreactive groups.\nThe smectic liquid crystal is aligned in layers parallel to the glass plates in\na sandwich geometry. This alignment offers several advantages, such as that\nmoderate electric fields are sufficient to achieve a high degree of polar\norder. The arrangement was then permanently fixed by photopolymerization which\nyielded a polar network possessing a high thermal and mechanical stability\nwhich did not show any sign of degradation within the monitored period of\nseveral months. The linear and nonlinear optical properties have been measured\nand all four independent components of the nonlinear susceptibility tensor\n$\\bar d$ have been determined. The off-resonant $d$-coefficients are remarkably\nhigh and comparable to those of the best known inorganic materials. The\nalignment led to an inherent channel waveguide for p-polarized light without\nadditional preparation steps. The photopolymerization did not induce scattering\nsites in the waveguide and the normalized losses were less than 2 dB/cm. The\nmaterial offers a great potential for the design of nonlinear optical devices\nsuch as frequency doublers of low power laser diodes.",
        "positive": "Hydrodynamics of thermally-driven chiral propulsion and separation: Considerable effort has been directed towards the characterization of chiral\nmesoscale structures, as shown in chiral protein assemblies and carbon\nnanotubes. Here, we establish a thermally-driven hydrodynamic description for\nthe actuation and separation of mesoscale chiral structures in a fluid medium.\nCross flow of a Newtonian liquid with a thermal gradient gives rise to chiral\nstructure propulsion and separation according to their handedness. In turn, the\nchiral suspension alters the liquid flow which thus acquires a transverse\n(chiral) velocity component. Since observation of the predicted effects\nrequires a low degree of sophistication, our work provides an efficient and\ninexpensive approach to test and calibrate chiral particle propulsion and\nseparation strategies."
    },
    {
        "anchor": "Vortex in liquid films from concentrated surfactant solutions containing\n  micelles and colloidal particles: Hypothesis: New dynamic phenomena can be observed in evaporating free liquid\nfilms from colloidal solutions with bimodal particle size distribution. Such\ndistributions are formed in a natural way in mixed (slightly turbid) solutions\nof cationic and anionic surfactants, where nanosized micelles coexist with\nmicronsized precipitated particles. Experiment: Without evaporation of water,\nthe films thin down to thickness < 100 nm. Upon water evaporation from the\nfilm, one observes spontaneous film thickening (above 300 nm) and appearance of\na dynamic vortex with a spot of thinner film in the center. The vortex wall has\na stepwise profile with step-height equal to the effective micelle diameter\n(ca. 8 nm) and up to 20-30 stratification steps. Results: For thicknesses\ngreater than 100 nm, stratification in foam films from micellar solutions has\nnever been observed so far. It evidences for the formation of a thick colloidal\ncrystal of micelles in the evaporating film. The role of the bigger,\nmicronsized particles is to form a filtration cake in the Plateau border, which\nsupports the thick film. The developed quantitative mechanical model shows that\nthe stepwise vortex profile is stabilized by the balance of hydrodynamic and\nsurface tension forces. Vortex is observed not only in films from catanionic\nsurfactant solutions, but also in films from silica and latex particle\nsuspensions, which contain smaller surfactant micelles.",
        "positive": "Characteristic features of self-avoiding active Brownian polymers under\n  linear shear flow: We present Brownian dynamics simulation results of a flexible linear polymer\nwith excluded-volume interactions under shear flow in the presence of active\nnoise. The active noise strongly affects the polymer's conformational and\ndynamical properties, such as the stretching in the flow direction and\ncompression in the gradient direction, shear-induced alignment, and shear\nviscosity. In the asymptotic limit of large activities and shear rates, the\npower-law scaling exponents of these quantities differ significantly from those\nof passive polymers. The chain's shear-induced stretching at a given shear rate\nis reduced by active noise, and it displays a non-monotonic behavior, where an\ninitial polymer compression is followed by its stretching with increasing\nactive force."
    },
    {
        "anchor": "Extraterrestrial sink dynamics in granular matter: A loosely packed bed of sand sits precariously on the fence between\nmechanically stable and flowing states. This has especially strong implications\nfor animals or vehicles needing to navigate sandy environments, which can sink\nand become stuck in a \"dry quicksand\" if their weight exceeds the yield stress\nof this fragile matter. While it is known that the contact stresses in these\nsystems are loaded by gravity, very little is known about the sinking dynamics\nof objects into loose granular systems under gravitational accelerations\ndifferent from the Earth's (g). A fundamental understanding of how objects sink\nin different gravitational environments is not only necessary for successful\nplanetary navigation and engineering, but it can also improve our understanding\nof celestial impact dynamics and crater geomorphology. Here we perform and\nexplain the first systematic experiments of the sink dynamics of objects into\ngranular media in different gravitational accelerations. By using an\naccelerating experimental apparatus, we explore gravitational conditions\nranging from 0.4g to 1.2g. With the aid of discrete element modeling\nsimulations, we reproduce these results and extend this range to include\nobjects as small as asteroids and as large as Jupiter. Surprisingly, we find\nthat the final sink depth is independent of the gravitational acceleration, an\nobservation with immediate relevance to the design of future extraterrestrial\nstructures land-roving spacecraft. Using a phenomenological equation of motion\nthat includes a gravity-loaded frictional term, we are able to quantitatively\nexplain the experimental and simulation results.",
        "positive": "Effective interactions in colloid - semipermeable membrane systems: We investigate effective interactions between a colloidal particle, immersed\nin a binary mixture of smaller spheres, and a semipermeable membrane. The\ncolloid is modeled as a big hard sphere and the membrane is represented as an\ninfinitely thin surface which is fully permeable to one of the smaller spheres\nand impermeable to the other one. Within the framework of the density\nfunctional theory we evaluate the depletion potentials, and we consider two\ndifferent approximate theories - the simple Asakura-Oosawa approximation and\nthe accurate White-Bear version of the fundamental measure theory. The\neffective potentials are compared with the corresponding potentials for a hard,\nnonpermeable wall. Using statistical-mechanical sum rules we argue that the\ncontact value of the depletion potential between a colloid and a semipermeable\nmembrane is smaller in magnitude than the potential between a colloid and a\nhard wall. Explicit calculations confirm that the colloid-semipermeable\nmembrane effective interactions are generally weaker than these near a hard\nnonpermeable wall. This effect is more pronounced for smaller osmotic\npressures. The depletion potential for a colloidal particle inside a\nsemipermeable vesicle is stronger than the potential for the colloidal particle\nlocated outside of a vesicle. We find that the asymptotic decay of the\ndepletion potential for the semipermeable membrane is similar to that for the\nnonpermeable wall and reflects the asymptotics of the total correlation\nfunction of the corresponding binary mixture of smaller spheres. Our results\ndemonstrate that the ability of the membrane to change its shape constitutes an\nimportant factor in determining the effective interactions between the\nsemipermeable membrane and the colloidal macroparticle."
    },
    {
        "anchor": "Assessing Position-Dependent Diffusion from Biased Simulations and\n  Markov State Model Analysis: A variety of enhanced statistical and numerical methods are now routinely\nused to extract comprehensible and relevant thermodynamic information from the\nvast amount of complex, high-dimensional data obtained from intensive molecular\nsimulations. The characterization of kinetic properties, such as diffusion\ncoefficients, of molecular systems with significantly high energy barriers, on\nthe other hand, has received less attention. Among others, Markov state models,\nin which the long-time statistical dynamics of a system is approximated by a\nMarkov chain on a discrete partition of configuration space, have seen\nwidespread use in recent years, with the aim of tackling these fundamental\nissues. Here we propose a general, automatic method to assess multidimensional\nposition-dependent diffusion coefficients within the framework of Markovian\nstochastic processes and Kramers-Moyal expansion. We apply the formalism to\none- and two-dimensional analytic potentials and data from explicit solvent\nmolecular dynamics simulations, including the water-mediated conformations of\nalanine dipeptide. Importantly, the developed algortihm presents significant\nimprovement compared to standard methods when the transport of solute across\nthree-dimensional heterogeneous porous media is studied, for example, the\nprediction of membrane permeation of drug molecules.",
        "positive": "Molecular dynamic simulation of wet water vapour transport in porous\n  medium: Studies of the transport of wet water vapour are relevant for various areas\nof human activity, including the construction and production of building\nmaterials, mining, agriculture, environmental safety of technological\nprocesses, scientific research. In particular, one of the methods for\nextracting highly viscous bitumen grades of oil from the subterranean depths is\nbased on the dilution of the contents of the porous medium by means of pumping\ncoolants. The simplest and environmentally friendly coolant is wet steam\ncontaining small drops of water. In addition, with the help of heated water\nvapour, the filtering elements of collectors are cleaned from sediments of the\nsolid phase (for example, paraffins, gas hydrates and ice floes) on the walls\nof the porous medium. For realistic modeling of the processes of filtration and\nheat and mass transfer during the injection of wet steam into a porous medium,\nit is necessary to investigate the characteristics of the interaction of\nsaturated water vapour with individual through-type pores. In this paper, a\nstudy was carried out through mathematical modelling of the dependence of the\ndiffusion rate of wet water vapour on the pressure difference outside the pore\nthat occurs when water vapour is injected into a porous medium. The\ndependencies of the diffusion rate on the pore cross section, the magnitude of\nvapour adsorption on the pore walls, as well as the effect of water vapour\ntemperature on all these processes were also investigated. Practical interest\nis the study of the influence of the rate of cooling of water vapour on the\ndiffusion rate and the adsorption of water vapour on the wall of the pores. The\ncalculations were carried out using a hybrid type model that combines molecular\ndynamics and macro-diffusion approaches to describe the interaction of water\nvapour with individual pores."
    },
    {
        "anchor": "Surface Tension of Acid Solutions: Fluctuations beyond the Non-linear\n  Poisson-Boltzmann Theory: We extend our previous study of surface tension of ionic solutions and apply\nit to the case of acids (and salts) with strong ion-surface interactions. These\nion-surface interactions yield a non-linear boundary condition with an\neffective surface charge due to adsorption of ions from the bulk onto the\ninterface. The calculation is done using the loop-expansion technique, where\nthe zero-loop (mean field) corresponds of the non-linear Poisson-Boltzmann\nequation. The surface tension is obtained analytically to one-loop order, where\nthe mean-field contribution is a modification of the Poisson-Boltzmann surface\ntension, and the one-loop contribution gives a generalization of the\nOnsager-Samaras result. Our theory fits well a wide range of different acids\nand salts, and is in accord with the reverse Hofmeister series for acids.",
        "positive": "Dense granular flow of mixtures of spheres and dumbbells down a rough\n  inclined plane: Segregation and rheology: We study the flow of equal-volume binary granular mixtures of spheres and\ndumbbells with different aspect ratios down a rough inclined plane, using the\ndiscrete element method. We consider two types of mixtures -- in the first type\nthe particles of the two species have equal volume but different aspect ratios\n(EV) and in the second type they have variable volumes and aspect ratios (VV).\nWe also use mixtures of spheres of two different sizes (SS) with the same\nvolume ratios as in the mixtures of the second type, as the base case. Based on\nthe study of Guillard, Forterre and Pouliquen [\\textit{J. Fluid Mech.}\n\\textbf{807}, R1--R11 (2016)], the inclination angle of the base for each\nmixture is adjusted and maintained at a high value to yield the same pressure\nand shear stress gradients for all mixtures and a high effective friction\n($\\mu$) for each. This ensures that the segregation force and resulting extent\nof segregation depend only the size and shape of the particles. The species\nwith larger effective size, computed in terms of the geometric mean diameter,\nfloats up in all cases and the dynamics of the segregation process for all the\nmixtures are reported. The concentration profiles of the species at steady\nstate agree well with the predictions of a continuum theory. The $\\mu-I$ and\n$\\phi-I$ scaling relations, where $I$ is the inertial number and $\\phi$ is the\nsolid volume fraction, extended to the case of mixtures, are shown to describe\nthe rheology for all the cases."
    },
    {
        "anchor": "Nonequilibrium Thermodynamics of Colloids: The common rules of classical nonequilibrium thermodynamics do not allow an\nOnsager coefficient like the viscosity to depend on the shear rate. Such a\ndependence is experimentally well documented, however. In this paper it is\nshown, using nonequilibrium thermodynamics alone, how it is possible that the\neffective viscosity coefficient of an isotropic colloidal system depends on\nboth the shear rate and the frequency.",
        "positive": "Characterization of microscopic deformation through two-point spatial\n  correlation function: The molecular rearrangements of most fluids under flow and deformation do not\ndirectly follow the macroscopic strain field. In this work, we describe a\nphenomenological method for characterizing such non-affine deformation via the\nanisotropic pair distribution function (PDF). We demonstrate now the\nmicroscopic strain can be calculated in both simple shear and uniaxial\nextension, by perturbation expansion of anisotropic PDF in terms of real\nspherical harmonics. Our results, given in the real as well as the reciprocal\nspace, can be applied in spectrum analysis of small-angle scattering\nexperiments and non-equilibrium molecular dynamics simulations of soft matter\nunder flow."
    },
    {
        "anchor": "Structural heterogeneity: a topological characteristic to track the time\n  evolution of soft matter systems: We introduce structural heterogeneity, a new topological characteristic for\nsemi-ordered materials that captures their degree of organisation at a\nmesoscopic level and tracks their time-evolution, ultimately detecting the\norder-disorder transition at the microscopic scale. Such quantitative\ncharacterisation of a complex, soft matter system has not yet been achieved\nwith any other method. We show that structural heterogeneity can track\nstructural changes in a liquid crystal nanocomposite, reveal the effect of\nconfined geometry on the nematic-isotropic and isotropic-nematic phase\ntransitions, and uncover physical differences between these two processes. The\nsystem used in this work is representative of a class of composite\nnanomaterials, partially ordered and with complex structural and physical\nbehaviour, where their precise characterisation poses significant challenges.\nOur newly developed analytic framework can provide both a qualitative and a\nquantitative characterisations of the dynamical behaviour of a wide range of\nsemi-ordered soft matter systems.",
        "positive": "Buckling Metamaterials for Extreme Vibration Damping: Damping mechanical resonances is a formidable challenge in an increasing\nnumber of applications. Many of the passive damping methods rely on using low\nstiffness dissipative elements, complex mechanical structures or electrical\nsystems, while active vibration damping systems typically add an additional\nlayer of complexity. However, in many cases, the reduced stiffness or\nadditional complexity and mass render these vibration damping methods\nunfeasible. Here, we introduce a method for passive vibration damping by\nallowing buckling of the primary load path, which sets an upper limit for\nvibration transmission: the transmitted acceleration saturates at a maximum\nvalue, no matter what the input acceleration is. This nonlinear mechanism leads\nto an extreme damping coefficient tan delta ~0.23 in our metal\nmetamaterial|orders of magnitude larger than the linear damping of traditional\nlightweight structural materials. We demonstrate this principle experimentally\nand numerically in free-standing rubber and metal mechanical metamaterials over\na range of accelerations, and show that bi-directional buckling can further\nimprove its performance. Buckling metamaterials pave the way towards extreme\nvibration damping without mass or stiffness penalty, and as such could be\napplicable in a multitude of high-tech applications, including aerospace\nstructures, vehicles and sensitive instruments."
    },
    {
        "anchor": "Why neural functionals suit statistical mechanics: We describe recent progress in the statistical mechanical description of\nmany-body systems via machine learning combined with concepts from density\nfunctional theory and many-body simulations. We argue that the neural\nfunctional theory by Samm\\\"uller et al. [Proc. Nat. Acad. Sci. 120, e2312484120\n(2023)] gives a functional representation of direct correlations and of\nthermodynamics that allows for thorough quality control and consistency\nchecking of the involved methods of artificial intelligence. Addressing a\nprototypical system we here present a pedagogical application to hard core\nparticle in one spatial dimension, where Percus' exact solution for the free\nenergy functional provides an unambiguous reference. A corresponding standalone\nnumerical tutorial that demonstrates the neural functional concepts together\nwith the underlying fundamentals of Monte Carlo simulations, classical density\nfunctional theory, machine learning, and differential programming is available\nonline at https://github.com/sfalmo/NeuralDFT-Tutorial.",
        "positive": "Bulk Modulus along Jamming Transition Lines of Bidisperse Granular\n  Packings: We present 3D DEM simulations of bidisperse granular packings to investigate\ntheir jamming densities, $\\phi_J$, and dimensionless bulk moduli, $K$, as a\nfunction of the size ratio, $\\delta$, and the concentration of small particles,\n$X_{\\mathrm S}$. We determine the partial and total bulk moduli for each\npacking and report the jamming transition diagram, i.e., the density or volume\nfraction marking both the first and second transitions of the system. At a\nlarge enough size difference, e.g., $\\delta \\le 0.22$, $X^{*}_{\\mathrm S}$\ndivides the diagram with most small particles either non-jammed or jammed\njointly with large ones. We find that the bulk modulus $K$ jumps at\n$X^{*}_{\\mathrm S}(\\delta = 0.15) \\approx 0.21$, at the maximum jamming\ndensity, where both particle species mix most efficiently, while for\n$X_{\\mathrm S} < X^{*}_{\\mathrm S}$ $K$ is decoupled in two scenarios as a\nresult of the first and second jamming transition. Along the second transition,\n$K$ rises relative to the values found at the first transition, however, is\nstill small compared to $K$ at $X^{*}_{\\mathrm S}$. While the first transition\nis sharp, the second is smooth, carried by small-large interactions, while the\nsmall-small contacts display a transition. This demonstrates that for low\nenough $\\delta$ and $X_{\\mathrm S}$, the jamming of small particles indeed\nimpacts the internal resistance of the system. Our new results will allow\ntuning the bulk modulus $K$ or other properties, such as the wave speed, by\nchoosing specific sizes and concentrations based on a better understanding of\nwhether small particles contribute to the jammed structure or not, and how the\nmicromechanical structure behaves at either transition."
    },
    {
        "anchor": "Building a \"trap model\" of glassy dynamics from a local structural\n  predictor of rearrangements: Here we introduce a variation of the trap model of glasses based on softness,\na local structural variable identified by machine learning, in supercooled\nliquids. Softness is a particle-based quantity that reflects the local\nstructural environment of a particle and characterizes the energy barrier for\nthe particle to rearrange. As in the trap model, we treat each particle's\nsoftness, and hence energy barrier, as evolving independently. We show that\nsuch a model reproduces many qualitative features of softness, and therefore\nmakes qualitatively reasonable predictions of behaviors such as the dependence\nof fragility on density in a model supercooled liquid. We also show failures of\nthis simple model, indicating features of the dynamics of softness that may\nonly be explained by correlations.",
        "positive": "Kramers-Kronig Relations for Nonlinear Rheology: 2. Validation of Medium\n  Amplitude Oscillatory Shear (MAOS) Measurements: The frequency dependence of third-harmonic medium amplitude oscillatory shear\n(MAOS) modulus $G_{33}^{*}(\\omega)$ provides insight into material behavior and\nmicrostructure in the asymptotically nonlinear regime. Motivated by the\ndifficulty in the measurement of MAOS moduli, we propose a test for data\nvalidation based on nonlinear Kramers-Kronig relations. We extend the approach\nused to assess the consistency of linear viscoelastic data by expressing the\nreal and imaginary parts of $G_{33}^{*}(\\omega)$ as a linear combination of\nMaxwell elements: the functional form for the MAOS kernels is inspired by\ntime-strain separability (TSS). We propose a statistical fitting technique\ncalled the SMEL test, which works well on a broad range of materials and models\nincluding those that do not obey TSS. It successfully copes with experimental\ndata that are noisy, or confined to a limited frequency range. When Maxwell\nmodes obtained from the SMEL test are used to predict the first-harmonic MAOS\nmodulus $G_{31}^{*}$, it is possible to identify the range of timescales over\nwhich a material exhibits TSS."
    },
    {
        "anchor": "Charged hydrophobic colloids at an oil/aqueous phase interface: Hydrophobic PMMA colloidal particles, when dispersed in oil with a relatively\nhigh dielectric constant, can become highly charged. In the presence of an\ninterface with a conducting aqueous phase, image charge effects lead to strong\nbinding of colloidal particles to the interface, even though the particles are\nwetted very little by the aqueous phase. In this paper, we study both the\nbehavior of individual colloidal particles as they approach the interface, and\nthe interactions between particles that are already interfacially bound. We\ndemonstrate that using particles which are minimally wetted by the aqueous\nphase allows us to isolate and study those interactions which are due solely to\ncharging of the particle surface in oil. Finally, we show that these\ninteractions can be understood by a simple image-charge model in which the\nparticle charge $q$ is the sole fitting parameter.",
        "positive": "Driven and active colloids at fluid interfaces: We derive expressions for the leading-order far-field flows generated by\nexternally driven and active (swimming) colloids at planar fluid-fluid\ninterfaces. We consider colloids adjacent to the interface or adhered to the\ninterface with a pinned contact line. The Reynolds and capillary numbers are\nassumed much less than unity, in line with typical micron-scale colloids\ninvolving air- or alkane-aqueous interfaces. For driven colloids, the\nleading-order flow is given by the point-force (and/or torque) response of this\nsystem. For active colloids, the force-dipole (stresslet) response occurs at\nleading order. At clean (surfactant-free) interfaces, these hydrodynamic modes\nare essentially a restricted set of the usual Stokes multipoles in a bulk\nfluid. To leading order, driven colloids exert Stokeslets parallel to the\ninterface, while active colloids drive differently oriented stresslets\ndepending on the colloid's orientation. We then consider how these modes are\naltered by the presence of an incompressible interface, a typical circumstance\nfor colloidal systems at small capillary numbers in the presence of surfactant.\nThe leading-order modes for driven and active colloids are restructured\ndramatically. For driven colloids, interfacial incompressibility substantially\nweakens the far-field flow normal to the interface; the point-force response\ndrives flow only parallel to the interface. However, Marangoni stresses induce\na new dipolar mode, which lacks an analogue on a clean interface.\nSurface-viscous stresses, if present, potentially generate very long-ranged\nflow on the interface and the surrounding fluids. Our results have important\nimplications for colloid assembly and advective mass transport enhancement near\nfluid boundaries."
    },
    {
        "anchor": "Simplicity and scaling - size of a real polymer in three (or any)\n  dimensions: We examine the scaling of the linear dimension of the system size of a real\npolymer solution at constant excess free energy and in two different spacial\ndimensionalities, d=d0 and d=d1. Standard results for the functional form of\nthe excess free energy lead to the conclusion that the scaling exponent nu(d)\nsatisfies nu(d0) - nu(d1) = 1/d0 - 1/d1. Taking the critical dimensionality as\na point of reference (nu(4)=1/2) gives a scaling exponent nu(d) = 1/4 +1/d, in\nagreement with the accepted result for two-dimensions (nu(2) = 3/4) and the\nfirst term in the epsilon (d-4) expansion. For the unsolved case of three\ndimensions it predicts nu(3)=7/12. Several simplifying features of this result\nare pointed out.",
        "positive": "Stochastic dynamics of granular hopper flows: a slow hidden mode\n  controls the stability of clogs: Granular flows in small-outlet hoppers exhibit intermittent clogging\nbehavior: while a temporary clog (pause) can last for an extended period before\nflow spontaneously restarts, there are also permanent clogs that last beyond\nexperimental timescales. Here, we introduce a phenomenological model with\nmultiplicative noise that provides a dynamical explanation for these extreme\nevents: they arise due to coupling between the flow rate and a slow hidden mode\nthat controls the stability of clogs. The theory fully resolves the statistics\nof pause and clog events, including the non-exponential clogging times and\nnon-Gaussian flow rate distribution and explains the stretched-exponential\ngrowth of the average clogging time with outlet size. Our work provides a\nframework for extracting features of granular flow dynamics from experimental\ntrajectories."
    },
    {
        "anchor": "Origami and materials science: Origami, the ancient art of folding thin sheets, has attracted increasing\nattention for its practical value in diverse fields: architectural design,\ntherapeutics, deployable space structures, medical stent design, antenna design\nand robotics. In this survey article we highlight its suggestive value for the\ndesign of materials. At continuum level the rules for constructing origami have\ndirect analogs in the analysis of the microstructure of materials. At atomistic\nlevel the structure of crystals, nanostructures, viruses and quasicrystals all\nlink to simplified methods of constructing origami. Underlying these linkages\nare basic physical scaling laws, the role of isometries, and the simplifying\nrole of group theory. Non-discrete isometry groups suggest an unexpected\nframework for the possible design of novel materials.",
        "positive": "Point Defect Dynamics in Two-Dimensional Colloidal Crystals: We study the topological configurations and dynamics of individual point\ndefect vacancies and interstitials in a two-dimensional colloidal crystal. Our\nBrownian dynamics simulations show that the diffusion mechanism for vacancy\ndefects occurs in two phases. The defect can glide along the crystal lattice\ndirections, and it can rotate during an excited topological transition\nconfiguration to assume a different direction for the next period of gliding.\nThe results for the vacancy defects are in good agreement with recent\nexperiments. For the interstitial point defects, which were not studied in the\nexperiments, we find several of the same modes of motion as in the vacancy\ndefect case along with two additional diffusion pathways. The interstitial\ndefects are more mobile than the vacancy defects due to the more\ntwo-dimensional nature of the diffusion of the interstitial defects."
    },
    {
        "anchor": "Measuring the deformation of a ferrogel sphere in a homogeneous magnetic\n  field: A sphere of a ferrogel is exposed to a homogeneous magnetic field. In\naccordance to theoretical predictions, it gets elongated along the field lines.\nThe time-dependence of the elastic shear modulus causes the elongation to\nincrease with time analogously to mechanic creep experiments, and the rapid\nexcitation causes the sphere to vibrate. Both phenomena can be well described\nby a damped harmonic oscillator model. By comparing the elongation along the\nfield with the contraction perpendicular to it, we can calculate Poisson's\nratio of the gel. The magnitude of the elongation is compared with the\ntheoretical predictions for elastic spheres in homogeneous fields.",
        "positive": "Stress representations for tensor basis neural networks: alternative\n  formulations to Finger-Rivlin-Ericksen: Data-driven constitutive modeling frameworks based on neural networks and\nclassical representation theorems have recently gained considerable attention\ndue to their ability to easily incorporate constitutive constraints and their\nexcellent generalization performance. In these models, the stress prediction\nfollows from a linear combination of invariant-dependent coefficient functions\nand known tensor basis generators. However, thus far the formulations have been\nlimited to stress representations based on the classical Rivlin and Ericksen\nform, while the performance of alternative representations has yet to be\ninvestigated. In this work, we survey a variety of tensor basis neural network\nmodels for modeling hyperelastic materials in a finite deformation context,\nincluding a number of so far unexplored formulations which use theoretically\nequivalent invariants and generators to Finger-Rivlin-Ericksen. Furthermore, we\ncompare potential-based and coefficient-based approaches, as well as different\ncalibration techniques. Nine variants are tested against both noisy and\nnoiseless datasets for three different materials. Theoretical and practical\ninsights into the performance of each formulation are given."
    },
    {
        "anchor": "Critical swelling of particle-encapsulating vesicles: We consider a ubiquitous scenario where a fluctuating, semipermeable vesicle\nis embedded in solution while enclosing a fixed number of solute particles. The\nswelling with increasing number of particles or decreasing concentration of the\nouter solution exhibits a continuous phase transition from a fluctuating state\nto the maximum-volume configuration, whereupon appreciable pressure difference\nand surface tension build up. This criticality is unique to\nparticle-encapsulating vesicles, whose volume and inner pressure both\nfluctuate. It implies a universal swelling behavior of such vesicles as they\napproach their limiting volume and osmotic lysis.",
        "positive": "Thinning or thickening? Multiple rheological regimes in dense\n  suspensions of soft particles: The shear rheology of dense colloidal and granular suspensions is strongly\nnonlinear, as these materials exhibit shear-thinning and shear-thickening,\ndepending on multiple physical parameters. We numerically study the rheology of\na simple model of soft repulsive particles at large densities, and show that\nnonlinear flow curves reminiscent of experiments on real suspensions can be\nobtained. By using dimensional analysis and basic elements of kinetic theory,\nwe rationalize these multiple rheological regimes and disentangle the relative\nimpact of thermal fluctuations, glass and jamming transitions, inertia and\nparticle softness on the flow curves. We characterize more specifically the\nshear-thickening regime and show that both particle softness and the emergence\nof a yield stress at the jamming transition compete with the inertial effects\nresponsible for the observed thickening behaviour. This allows us to construct\na dynamic state diagram, which can be used to analyze experiments."
    },
    {
        "anchor": "Plasticity-Induced Magnetization in Amorphous Magnetic Solids: Amorphous magnetic solids, like metallic glasses, exhibit a novel effect: the\ngrowth of magnetic order as a function of mechanical strain under athermal\nconditions in the presence of a magnetic field. The magnetic moment increases\nin steps whenever there is a plastic event. Thus plasticity induces the\nmagnetic ordering, acting as the effective noise driving the system towards\nequilibrium. We present results of atomistic simulations of this effect in a\nmodel of a magnetic amorphous solid subjected to pure shear and a magnetic\nfield. To elucidate the dependence on external strain and magnetic field we\noffer a mean-field theory that provides an adequate qualitative understanding\nof the observed phenomenon.",
        "positive": "Vapor condensation onto a non-volatile liquid drop: Molecular dynamics simulations of miscible and partially miscible binary\nLennard--Jones mixtures are used to study the dynamics and thermodynamics of\nvapor condensation onto a non-volatile liquid drop in the canonical ensemble.\nWhen the system volume is large, the driving force for condensation is low and\nonly a submonolayer of the solvent is adsorbed onto the liquid drop. A small\ndegree of mixing of the solvent phase into the core of the particles occurs for\nthe miscible system. At smaller volumes complete film formation is observed and\nthe dynamics of film growth are dominated by cluster-cluster coalescence.\nMixing into the core of the droplet is also observed for partially miscible\nsystems below an onset volume suggesting, the presence of a solubility\ntransition. We also develop a non-volatile liquid drop model, based on the\ncapillarity approximations, that exhibits a solubility transition between small\nand large drops for partially miscible mixtures and has a hysteresis loop\nsimilar to the one observed in the deliquescence of small soluble salt\nparticles. The properties of the model are compared to our simulation results\nand the model is used to study the formulation of classical nucleation theory\nfor systems with low free energy barriers."
    },
    {
        "anchor": "Field - Driven Translocation of Regular Block Copolymers through a\n  Selective Liquid - Liquid Interface: We propose a simple scaling theory describing the variation of the mean first\npassage time (MFPT) $\\tau(N,M)$ of a regular block copolymer of chain length\n$N$ and block size $M$ which is dragged through a selective liquid-liquid\ninterface by an external field $B$. The theory predicts a non-Arrhenian $\\tau$\nvs. $B$ relationship which depends strongly on the size of the blocks, $M$, and\nrather weakly on the total polymer length, $N$. The overall behavior is\nstrongly influenced by the degree of selectivity between the two solvents\n$\\chi$.\n  The variation of $\\tau(N,M)$ with $N$ and $M$ in the regimes of weak and\nstrong selectivity of the interface is also studied by means of computer\nsimulations using a dynamic Monte Carlo coarse-grained model. Good qualitative\nagreement with theoretical predictions is found. The MFPT distribution is found\nto be well described by a $\\Gamma$ - distribution. Transition dynamics of ring-\nand telechelic polymers is also examined and compared to that of the linear\nchains.\n  The strong sensitivity of the ``capture'' time $\\tau(N,M)$ with respect to\nblock length $M$ suggests a possible application as a new type of\nchromatography designed to separate and purify complex mixtures with different\nblock sizes of the individual macromolecules.",
        "positive": "Study of wet mesostructure silica MCM-41 by low frequency dielectric\n  spectroscopy: The dielectric measurements of mesostructured silica MCM-41 with the pore\ndiameter 3.5 nm at wettings close to maximal were carried out. The measurements\nwere made by using the dielectric spectroscopy method at frequency interval\nfrom 25Hz up to 1MHz and for cooling from 23{\\deg}C to -70{\\deg}C. The phase\ntransition near -40{\\deg}C was observed. It is supposed that liquid crystal\nstate exists at higher temperatures of point phase transition. For lower\ntemperatures there were two phases, with one of them being ferroelectric."
    },
    {
        "anchor": "On the deflection of light by topological defects in nematic liquid\n  crystals: The influence of controlable parameters like temperature and wavelength on\nthe trajectories of light in a nematic liquid crystal with topological defects\nis studied through a geometric model. The model incorporates phenomenological\ndetails as how the refractive indices depend on such parameters. The deflection\nof light by the topological defect is then shown to be greater at lower\ntemperatures and shorter wavelengths.",
        "positive": "Shape and symmetry of a fluid-supported elastic sheet: A connection between the dynamics of a sine-Gordon chain and a certain static\nmembrane folding problem was recently found. The one-dimensional membrane\nprofile is a cross-section of the position-time sine-Gordon amplitude profile.\nHere we show that when one system is embedded in a higher-dimensional system in\nthis way, obvious symmetries in the larger system can lead to nontrivial\nsymmetries in the embedded system. In particular, a thin buckled membrane on a\nfluid substrate has a continuous degeneracy that interpolates between a\nsymmetric and an antisymmetric fold. We find the Hamiltonian generator of this\nsymmetry and the corresponding conserved momentum by interpreting the simple\ntranslational symmetries of the sine-Gordon chain in terms of the embedded\ncoordinates. We discuss possible extensions to other embedded dynamical\nsystems."
    },
    {
        "anchor": "On the Coupling between Ionic Conduction and Dipolar Relaxation in Deep\n  Eutectic Solvents: Influence of Hydration and Glassy Dynamics: We have studied the ionic conductivity and the dipolar reorientational\ndynamics of aqueous solutions of a prototypical deep eutectic solvent (DES),\nethaline, by using dielectric spectroscopy on a broad range of frequency\n(MHz-Hz) and for temperatures ranging from 128 to 283 K. The fraction of water\nin the DES was varied systematically to cover different regimes, starting from\npure DES and its water-in-DES mixtures to the diluted electrolyte solutions.\nDepending on these parameters, different physical states were examined,\nincluding low viscosity liquid, supercooled viscous liquid, amorphous solid and\nfreeze-concentrated solution. The ionic conductivity and the reorientational\nrelaxation both exhibited characteristic features of glassy dynamics that could\nbe quantified from the deviation from Arrhenius temperature dependence and\nnon-exponential decay of the relaxation function. A transition occurred between\nthe water-in-DES regime, (< 40 wt %),where the dipolar relaxation and ionic\nconductivity remained inversely proportional to each other, and the\nDES-in-water regime, (> 40 wt %), where a clear rotation-translation decoupling\nwas observed. This suggests that for low water content, on the timescale\ncovered by this study (~10-6 s to 1 s), the rotational and transport properties\nof ethaline aqueous solutions obey classical hydrodynamic scaling despite these\nsystems being presumably spatially microheterogeneous. A fractional scaling is\nobserved in the DES-in-water regime, due to the formation of a maximally\nfreeze-concentrated DES aqueous solution coexisting with frozen water domains\nat sub-ambient temperature.",
        "positive": "Thermodynamics and Structural Properties of the High Density Gaussian\n  Core Model: We numerically study thermodynamic and structural properties of the\none-component Gaussian core model (GCM) at very high densities. The solid-fluid\nphase boundary is carefully determined. We find that the density dependence of\nboth the freezing and melting temperatures obey the asymptotic relation, $\\log\nT_f$, $\\log T_m \\propto -\\rho^{2/3}$, where $\\rho$ is the number density, which\nis consistent with Stillinger's conjecture. Thermodynamic quantities such as\nthe energy and pressure and the structural functions such as the static\nstructure factor are also investigated in the fluid phase for a wide range of\ntemperature above the phase boundary. We compare the numerical results with the\nprediction of the liquid theory with the random phase approximation (RPA). At\nhigh temperatures, the results are in almost perfect agreement with RPA for a\nwide range of density, as it has been already shown in the previous studies. In\nthe low temperature regime close to the phase boundary line, although RPA fails\nto describe the structure factors and the radial distribution functions at the\nlength scales of the interparticle distance, it successfully predicts their\nbehaviors at shorter length scales. RPA also predicts thermodynamic quantities\nsuch as the energy, pressure, and the temperature at which the thermal\nexpansion coefficient becomes negative, almost perfectly. Striking ability of\nRPA to predict thermodynamic quantities even at high densities and low\ntemperatures is understood in terms of the decoupling of the length scales\nwhich dictate thermodynamic quantities from the interparticle distance which\ndominates the peak structures of the static structure factor due to the\nsoftness of the Gaussian core potential."
    },
    {
        "anchor": "Weakly faceted cellular patterns versus growth-induced plastic\n  deformation in thin-sample directional solidification of monoclinic biphenyl: We present an experimental study of thin-sample directional solidification\n(T-DS) in impure biphenyl. The plate-like growth shape of the monoclinic\nbiphenyl crystals includes two low-mobility (001) facets and four high-mobility\n{110} facets. Upon T-DS, biphenyl plates oriented with (001) facets parallel to\nthe sample plane can exhibit either a strong growth-induced plastic deformation\n(GID), or deformation-free weakly faceted (WF) growth patterns. We determine\nthe respective conditions of appearance of these phenomena. GID is shown to be\na long-range thermal-stress effect, which disappears when the growth front has\na cellular structure. An early triggering of the cellular instability allowed\nus to avoid GID and study the dynamics of WF patterns as a function of the\norientation of the crystal.",
        "positive": "The binding dynamics of tropomyosin on actin: We discuss a theoretical model for the cooperative binding dynamics of\ntropomyosin to actin filaments. Tropomyosin binds to actin by occupying seven\nconsecutive monomers. The model includes a strong attraction between attached\ntropomyosin molecules. We start with an empty lattice and show that the binding\ngoes through several stages. The first stage represents fast initial binding\nand leaves many small vacancies between blocks of bound molecules. In the\nsecond stage the vacancies annihilate slowly as tropomyosin molecules detach\nand re-attach. Finally the system approaches equilibrium. Using a grain-growth\nmodel and a diffusion-coagulation model we give analytical approximations for\nthe vacancy density in all regimes."
    },
    {
        "anchor": "Poly-Sarcosine and Poly(ethylene-glycol) interactions with proteins\n  investigated using molecular dynamics simulations: Nanoparticles coated with hydrophilic polymers often show a reduction in\nunspecific interactions with the biological environment, which improves their\nbiocompatibility. The molecular determinants of this reduction are not very\nwell understood yet, and their knowledge may help improving nanoparticle\ndesign. Here we address, using molecular dynamics simulations, the interactions\nof human serum albumin, the most abundant serum protein, with two promising\nhydrophilic polymers used for the coating of therapeutic nanoparticles,\npoly(ethylene-glycol) and poly-sarcosine. By simulating the protein immersed in\na polymer-water mixture, we show that the two polymers have a very similar\naffinity for the protein surface, both in terms of the amount of polymer\nadsorbed and also in terms of the type of amino acids mainly involved in the\ninteractions. We further analyze the kinetics of adsorption and how it affects\nthe polymer conformations. Minor differences between the polymers are observed\nin the thickness of the adsorption layer, that are related to the different\ndegree of flexibility of the two molecules. In comparison poly-alanine, an\nisomer of poly-sarcosine known to self-aggregate and induce protein\naggregation, shows a significantly larger affinity for the protein surface than\nPEG and PSar, which we show to be related not to a different patterns of\ninteractions with the protein surface, but to the different way the polymer\ninteracts with water.",
        "positive": "Transition to Superfluid Turbulence: Turbulence in superfluids depends crucially on the dissipative damping in\nvortex motion. This is observed in the B phase of superfluid 3He where the\ndynamics of quantized vortices changes radically in character as a function of\ntemperature. An abrupt transition to turbulence is the most peculiar\nconsequence. As distinct from viscous hydrodynamics, this transition to\nturbulence is not governed by the velocity-dependent Reynolds number, but by a\nvelocity-independent dimensionless parameter 1/q which depends only on the\ntemperature-dependent mutual friction -- the dissipation which sets in when\nvortices move with respect to the normal excitations of the liquid. At large\nfriction and small values of 1/q < 1 the dynamics is vortex number conserving,\nwhile at low friction and large 1/q > 1 vortices are easily destabilized and\nproliferate in number. A new measuring technique was employed to identify this\nhydrodynamic transition: the injection of a tight bundle of many small vortex\nloops in applied vortex-free flow at relatively high velocities. These vortices\nare ejected from a vortex sheet covering the AB interface when a two-phase\nsample of 3He-A and 3He-B is set in rotation and the interface becomes unstable\nat a critical rotation velocity, triggered by the superfluid Kelvin-Helmholtz\ninstability."
    },
    {
        "anchor": "Non-local effects in inhomogeneous flows of soft athermal disks: We numerically investigate non-local effects on inhomogeneous flows of soft\nathermal disks close to but below their jamming transition. We employ molecular\ndynamics to simulate Kolmogorov flows, in which a sinusoidal flow profile with\nfixed wave number is externally imposed, resulting in a spatially inhomogeneous\nshear rate. We find that the resulting rheology is strongly wave\nnumber-dependent, and that particle migration, while present, is not sufficient\nto describe the resulting stress profiles within a conventional local model. We\nshow that, instead, stress profiles can be captured with non-local constitutive\nrelations that account for gradients to fourth order. Unlike nonlocal flow in\nyield stress fluids, we find no evidence of a diverging length scale.",
        "positive": "Escape dynamics of a self-propelled nanorod from circular confinements\n  with narrow openings: We perform computer simulations to explore the escape dynamics of a\nself-propelled (active) nanorod from circular confinements with narrow\nopening(s). Our results clearly demonstrate how the persistent and directed\nmotion of the nanorod helps it to escape. Such escape events are absent if the\nnanorod is passive. To quantify the escape dynamics, we compute the radial\nprobability density function (RPDF) and mean first escape time (MFET) and show\nhow the activity is responsible for the bimodality of RPDF, which is clearly\nabsent if the nanorod is passive. The broadening of displacement distributions\nwith activity has also been observed. The computed mean first escape time\ndecreases with activity. In contrast, the fluctuations of the first escape\ntimes vary in a non-monotonic way. This results high values of the coefficient\nof variation and indicates the presence of multiple timescales in first escape\ntime distributions and multimodality in uniformity index distributions. We hope\nour study will help in differentiating activity-driven escape dynamics from\npurely thermal passive diffusion in confinement."
    },
    {
        "anchor": "Strain-rate and temperature-driven transition in the shear\n  transformation zone for two-dimensional amorphous solids: We couple the recently developed self-learning metabasin escape algorithm,\nwhich enables efficient exploration of the potential energy surface (PES), with\nshear deformation to elucidate strain-rate and temperature effects on the shear\ntransformation zone (STZ) characteristics in two-dimensional amorphous solids.\nIn doing so, we report a transition in the STZ characteristics that can be\nobtained through either increasing the temperature or decreasing the strain\nrate. The transition separates regions having two distinct STZ characteristics.\nSpecifically, at high temperatures and high strain rates, we show that the STZs\nhave characteristics identical to those that emerge from purely strain-driven,\nathermal quasistatic atomistic calculations. At lower temperatures and\nexperimentally relevant strain rates, we use the newly coupled PES + shear\ndeformation method to show that the STZs have characteristics identical to\nthose that emerge from a purely thermally activated state. The specific changes\nin STZ characteristics that occur in moving from the strain-driven to thermally\nactivated STZ regime include a 33% increase in STZ size, faster spatial decay\nof the displacement field, a change in the deformation mechanism inside the STZ\nfrom shear to tension, a reduction in the stress needed to nucleate the first\nSTZ, and finally a notable loss in characteristic quadrupolar symmetry of the\nsurrounding elastic matrix that has previously been seen in athermal,\nquasistatic shear studies of STZs.",
        "positive": "Pattern formation in desiccated sessile colloidal droplets with salt\n  admixture: Short review: This short review is devoted to the simple process of drying a\nmulti-component droplet consisting of a complex fluid containing a salt. These\nprocesses provide a fascinating subject for study. The explanation of the rich\nvariety of patterns formed is not only an academic challenge, but a problem of\npractical importance, as applications are growing in medical diagnosis and\nimprovement of coating/printing technology. The fundamental scientific problem\nis the study of the mechanism of micro- and nanoparticle self-organization in\nopen systems. The specific fundamental problem to be solved, related to this\nsystem is - the investigation of the mass transfer processes, the formation and\nevolution of phase fronts and the identification of mechanisms of pattern\nformation. The drops of liquid containing dissolved substances and suspended\nparticles are assumed to be drying on a horizontal solid substrate. The\nchemical composition and macroscopic properties of the complex fluid, the\nconcentration and nature of the salt, the surface energy of the substrate and\nthe interaction between the fluid and substrate which determines the wetting,\nall affect the final morphology of the dried film."
    },
    {
        "anchor": "Heterogeneous surface charge confining an electrolyte solution: The structure of dilute electrolyte solutions close to a surface carrying a\nspatially inhomogeneous surface charge distribution is investigated by means of\nclassical density functional theory (DFT) within the approach of fundamental\nmeasure theory (FMT). For electrolyte solutions the influence of these\ninhomogeneities is particularly strong because the corresponding characteristic\nlength scale is the Debye length, which is large compared to molecular sizes.\nHere a fully three-dimensional investigation is performed, which accounts\nexplicitly for the solvent particles, and thus provides insight into effects\ncaused by ion-solvent coupling. The present study introduces a versatile\nframework to analyze a broad range of types of surface charge heterogeneities\neven beyond the linear response regime. This reveals a sensitive dependence of\nthe number density profiles of the fluid components and of the electrostatic\npotential on the magnitude of the charge as well as on details of the surface\ncharge patterns at small scales.",
        "positive": "Volumetric formulation of lattice Boltzmann models with energy\n  conservation: We analyze a volumetric formulation of lattice Boltzmann for compressible\nthermal fluid flows. The velocity set is chosen with the desired accuracy,\nbased on the Gauss-Hermite quadrature procedure, and tested against controlled\nproblems in bounded and unbounded fluids. The method allows the simulation of\nthermohydrodyamical problems without the need to preserve the exact\nspace-filling nature of the velocity set, but still ensuring the exact\nconservation laws for density, momentum and energy. Issues related to boundary\ncondition problems and improvements based on grid refinement are also\ninvestigated."
    },
    {
        "anchor": "Growth Kinetics of the Homogeneously Nucleated Water Droplets:\n  Simulation Results: The growth of homogeneously nucleated droplets in water vapor at the fixed\ntemperatures T=273, 283, 293, 303, 313, 323, 333, 343, 353, 363 and 373 K (the\npressure $p=1$ atm.) is investigated on the basis of the coarse-grained\nmolecular dynamics simulation data with the mW-model. The treatment of\nsimulation results is performed by means of the statistical method within the\nmean-first-passage-time approach, where the reaction coordinate is associated\nwith the largest droplet size. It is found that the water droplet growth is\ncharacterized by the next features: (i) the rescaled growth law is unified at\nall the considered temperatures and (ii) the droplet growth evolves with\nacceleration and follows the power law.",
        "positive": "Counter-ions at Charged Walls: Two Dimensional Systems: We study equilibrium statistical mechanics of classical point counter-ions,\nformulated on 2D Euclidean space with logarithmic Coulomb interactions\n(infinite number of particles) or on the cylinder surface (finite particle\nnumbers), in the vicinity of a single uniformly charged line (one single\ndouble-layer), or between two such lines (interacting double-layers). The\nweak-coupling Poisson-Boltzmann theory, which applies when the coupling\nconstant Gamma is small, is briefly recapitulated (the coupling constant is\ndefined as Gamma = beta e^2 where beta is the inverse temperature, and e the\ncounter-ion charge). The opposite strong-coupling limit (Gamma -> infinity) is\ntreated by using a recent method based on an exact expansion around the\nground-state Wigner crystal of counter-ions. The weak- and strong-coupling\ntheories are compared at intermediary values of the coupling constant Gamma=2\ngamma (gamma=1,2,3), to exact results derived within a 1D lattice\nrepresentation of 2D Coulomb systems in terms of anti-commuting field\nvariables. The models (density profile, pressure) are solved exactly for any\nparticles numbers N at Gamma=2 and up to relatively large finite N at Gamma=4\nand 6. For the one-line geometry, the decay of the density profile at\nasymptotic distance from the line undergoes a fundamental change with respect\nto the mean-field behavior at Gamma=6. The like-charge attraction regime,\npossible in the strong coupling limit but precluded at mean-field level,\nsurvives for Gamma=4 and 6, but disappears at Gamma=2."
    },
    {
        "anchor": "From the bulk electrolyte solution to the electrochemical interface: This paper is aiming at presenting some relevant contributions of Jean-Pierre\nBadiali during the first ten years of his growing scientific activity. This\npresentation does not contain new materials but is based on a number of\nselected papers published in the seventies, a part of them written in French.\nThe presentation is organized around three points. The first point,\ncorresponding to his PhD thesis, is concerned with the study of ion-solvent and\nion-ion interactions in a solution using complex dielectric permittivity\nmeasurements in the Hertzian and microwave frequency range. The second one is\nconcerned with an analysis of the ion pair absorption band observed in the far\ninfrared region in terms of an interionic potential energy. The third one is\nconcerned with the metal-solution interface and his significant advances on (i)\nthe Lippmann equation linking electrocapillary and electrical measurements and\n(ii) the contribution of the metal to the differential interfacial capacity.",
        "positive": "Projection of strong coupling interaction with thermal bath in a polymer: We investigate modifications of a stochastic polymer picture through a shift\nin the boundary between the system and an external environment. A conventional\nbead-and-spring model serving as the coarse-graining model is given by the\nLangevin equation for all the monomers subject to white noise. However,\nstochastic motion for only a tagged monomer is observed to occur in the\npresence of colored noise. The qualitative change in the observations arises\nfrom the boundary shift decided by the observer. The Langevin dynamics analyses\ninterpret the colored noise as the emergence of the polymeric elastic force,\nresulting in additional heat in the tagged monomer observation. Being\ndistinguished from coarse-graining based on scale separation, the projection of\ncomparable internal degrees of freedom is also discussed in light of the\nfluctuation theorem and the stochastic polymer thermodynamics."
    },
    {
        "anchor": "Long time simulations of granular hydrodynamics : instabilities and\n  attractors: Using a hydrodyamic model of granular flows, we present very long time\nsimulations of a granular fluid in two dimensions without gravity and with\nperiodic boundary conditions in a square domain. Depending upon the values of\nthe viscosity, thermal conductivity and dissipation, we find for intermediate\ntimes a metastable clustering state. For longer times the system is attracted\nto either a shear band or a vortex state. Our results are in general agreement\nwith molecular dynamics simulations.",
        "positive": "Electro-optical memory of a nematic liquid crystal doped by multi-walled\n  carbon nanotubes: A pronounced irreversible electro-optical response (memory effect) has been\nrecently observed for nematic liquid crystal (LC) EBBA doped by multi-walled\ncarbon nanotubes (MWCNTs) near the percolation threshold of the MWCNTs\n(0.02-0.05 wt. %). It is caused by irreversible homeotropic-to-planar\nreorientation of LC in an electric field. This feature is explained by\nelectro-hydrodynamically stimulated dispergation of MWCNTs in LC and by the\nformation of a percolation MWCNT network which acts as a spatially distributed\nsurface stabilizing the planar state of the LC. This mechanism is confirmed by\nthe absence of memory in the EBBA/MWCNT composites, whose original structure is\nfixed by a polymer. The observed effect suggests new operation modes for the\nmemory type and bistable LC devices, as well as a method for \\textit{in situ}\ndispergation of carbon nanotubes in LC cells."
    },
    {
        "anchor": "Clustering and phase behaviour of attractive active particles with\n  hydrodynamics: We simulate clustering, phase separation and hexatic ordering in a\nmonolayered suspension of active squirming disks subject to an attractive\nLennard-Jones-like pairwise interaction potential, taking hydrodynamic\ninteractions between the particles fully into account. By comparing the\nhydrodynamic case with counterpart simulations for passive and active Brownian\nparticles, we elucidate the relative roles of self-propulsion, interparticle\nattraction, and hydrodynamic interactions in determining clustering and phase\nbehaviour. Even in the presence of an attractive potential, we find that\nhydrodynamic interactions strongly suppress the motility induced phase\nseparation that might a priori have been expected in a highly active\nsuspension. Instead, we find only a weak tendency for the particles to form\nstringlike clusters in this regime. At lower activities we demonstrate phase\nbehaviour that is broadly equivalent to that of the counterpart passive system\nat low temperatures, characterized by regimes of gas-liquid, gas-solid and\nliquid-solid phase coexistence. In this way, we suggest that a dimensionless\nquantity representing the level of activity relative to the strength of\nattraction plays the role of something like an effective non-equilibrium\ntemperature, counterpart to the (dimensionless) true thermodynamic temperature\nin the passive system. However there are also some important differences from\nthe equilibrium case, most notably with regards the degree of hexatic ordering,\nwhich we discuss carefully.",
        "positive": "Testing constitutive relations by running and walking on cornstarch and\n  water suspensions: The ability of a person to run on the surface of a suspension of cornstarch\nand water has fascinated scientists and the public alike. However, the\nconstitutive relation obtained from traditional steady-state rheology of\ncornstarch and water suspensions has failed to explain this behavior. In a\nprevious paper, we presented an averaged constitutive relation for impact\nrheology consisting of an effective compressive modulus of a system-spanning\ndynamically jammed structure (arXiv:1407:0719). Here, we show that this\nconstitutive model can be used to quantitatively predict, for example, the\ntrajectory and penetration depth of the foot of a person walking or running on\ncornstarch and water. The ability of the constitutive relation to predict the\nmaterial behavior in a case with different forcing conditions and flow geometry\nthan it was obtained from suggests that the constitutive relation could be\napplied more generally. We also present a detailed calculation of the added\nmass effect to show that while it may be able to explain some cases of people\nrunning or walking on the surface of cornstarch and water for pool depths $H\n>1.2$ m and foot impact velocities $V_I> 1.7$ m/s, it cannot explain\nobservations of people walking or running on the surface of cornstarch and\nwater for smaller $H$ or $V_I$."
    },
    {
        "anchor": "Length-scale Dependence of Stokes-Einstien Breakdown in Active\n  Glass-forming Liquids: Stokes-Einstein (SE) relation, which relates diffusion constant with the\nviscosity of a liquid at high temperatures in equilibrium, is violated in the\nsupercooled temperature regime. Whether this relation is obeyed in\nnonequilibrium active liquids is a question of significant current interest to\nthe statistical physics community trying to develop the theoretical framework\nof nonequilibrium statistical mechanics. Via extensive computer simulations of\nmodel active glass-forming liquids in three dimensions, we show that SE is\nobeyed at a high temperature similar to the equilibrium behaviour, and it gets\nviolated in the supercooled temperature regimes. The degree of violation\nincreases systematically with the increasing activity which quantifies the\namount the system is driven out of equilibrium. First passage-time (FPT)\ndistributions helped us to gain insights into this enhanced breakdown from the\nincreased short-time peak, depicting hoppers. Subsequently, we study the wave\nvector dependence of SE relation and show that it gets restored at a wave\nvector that decreases with increasing activity, and the cross-over wave vector\nis found to be proportional to the inverse of the dynamical heterogeneity\nlength scale in the system. Our work showed how SE violation in active\nsupercooled liquids could be rationalized using the growth of dynamic length\nscale, which is found to grow enormously with increasing activity in these\nsystems.",
        "positive": "Shear rheology of a dilute emulsion of ferrofluid droplets dispersed in\n  a non-magnetizable carrier fluid under the influence of a uniform magnetic\n  field: The effect of a spatially uniform magnetic field on the shear rheology of a\ndilute emulsion of monodispersed ferrofluid droplets, immersed in a\nnon-magnetizable immiscible fluid, is investigated using direct numerical\nsimulations. The direction of the applied magnetic field is normal to the shear\nflow direction. The droplets extra stress tensor arising from the presence of\ninterfacial forces of magnetic nature is modeled on the basis of the seminal\nwork of G. K. Batchelor, J. Fluid Mech., 41.3 (1970) under the assumptions of a\nlinearly magnetizable ferrofluid phase and negligible inertia. The results show\nthat even relatively small magnetic fields can have significant consequences on\nthe rheological properties of the emulsion due to the magnetic forces that\ncontribute to deform and orient the droplets towards the direction of the\napplied magnetic vector. In particular, we have observed an increase of the\neffective (bulk) viscosity and a reversal of the sign of the two normal stress\ndifferences with respect to the case without magnetic field for those\nconditions where the magnetic force prevails over the shearing force.\nComparisons between the results of our model with a direct integration of the\nviscous stress have provided an indication of its reliability to predict the\neffective viscosity of the suspension. Moreover, this latter quantity has been\nfound to behave as a monotonic increasing function of the applied magnetic\nfield for constant shearing flows (\"magneto-thickening\" behaviour), which\nallowed us to infer a simple constitutive equation describing the emulsion\nviscosity."
    },
    {
        "anchor": "Conformation and dynamics of partially active linear polymers: We perform numerical simulations of isolated, partially active polymers,\ndriven out-of-equilibrium by a fraction of their monomers. We show that, if the\nactive beads are all gathered in a contiguous block, the position of the\nsection along the chain determines the conformational and dynamical properties\nof the system. Notably, one can modulate the diffusion coefficient of the\npolymer from {active-like to passive-like} just by changing the position of the\nactive block. Further, in special cases, enhancement of diffusion can be\nachieved by decreasing the overall polymer activity. Our findings may help in\nthe modelization of active biophysical systems, such as filamentous bacteria or\nworms.",
        "positive": "Poisson-Bracket Approach to the Dynamics of Bent-Core Molecules: We generalize our previous work on the phase stability and hydrodynamic of\npolar liquid crystals possessing local uniaxial $C_{\\infty v}$-symmetry to\nbiaxial systems exhibiting local $C_{2v}$-symmetry. Our work is motivated by\nthe recently discovered examples of thermotropic biaxial nematic liquid\ncrystals comprising bent-core mesogens, whose molecular structure is\ncharacterized by a non-polar body axis $({\\bf{n}})$ as well as a polar axis\n$({\\bf{p}})$ along the bisector of the bent mesogenic core which is coincident\nwith a large, transverse dipole moment. The free energy for this system differs\nfrom that of biaxial nematic liquid crystals in that it contains terms\nviolating the ${\\bf{p}}\\to -{\\bf{p}}$ symmetry. We show that, in spite of a\ngeneral splay instability associated with these parity-odd terms, a uniform\npolarized biaxial state can be stable in a range of parameters. We then derive\nthe hydrodynamic equations of the system, via the Poisson-bracket formalism, in\nthe polarized state and comment on the structure of the corresponding linear\nhydrodynamic modes. In our Poisson-bracket derivation, we also compute the\nflow-alignment parameters along the three symmetry axes in terms of microscopic\nparameters associated with the molecular geometry of the constituent biaxial\nmesogens."
    },
    {
        "anchor": "Capillary adhesion between elastic solids with randomly rough surfaces: I study how the contact area and the work of adhesion, between two elastic\nsolids with randomly rough surfaces, depend on the relative humidity. The\nsurfaces are assumed to be hydrophilic, and capillary bridges form at the\ninterface between the solids. For elastically hard solids with relative smooth\nsurfaces, the area of real contact and therefore also the sliding friction, are\nmaximal when there is just enough liquid to fill out the interfacial space\nbetween the solids, which typically occurs for $d_{\\rm K} \\approx 3 h_{\\rm\nrms}$, where $d_{\\rm K}$ is the height of the capillary bridge and $h_{\\rm\nrms}$ the root-mean-square roughness of the (combined) surface roughness\nprofile. For elastically soft solids, the area of real contact is maximal for\nvery low humidity (i.e., small $d_{\\rm K}$), where the capillary bridges are\nable to pull the solids into nearly complete contact. In both case, the work of\nadhesion is maximal (and equal to $2\\gamma {\\rm cos}\\theta$, where $\\gamma$ is\nthe liquid surface tension and $\\theta$ the liquid-solid contact angle) when\n$d_{\\rm K} >> h_{\\rm rms}$, corresponding to high relative humidity.",
        "positive": "Colloids with key-lock interactions: non-exponential relaxation, aging\n  and anomalous diffusion: The dynamics of particles interacting by key-lock binding of attached\nbiomolecules are studied theoretically. Experimental realizations of such\nsystems include colloids grafted with complementary single-stranded DNA\n(ssDNA), and particles grafted with antibodies to cell-membrane proteins.\nDepending on the coverage of the functional groups, we predict two distinct\nregimes. In the low coverage localized regime, there is an exponential\ndistribution of departure times. As the coverage is increased the system enters\na diffusive regime resulting from the interplay of particle desorption and\ndiffusion. This interplay leads to much longer bound state lifetimes, a\nphenomenon qualitatively similar to aging in glassy systems. The diffusion\nbehavior is analogous to dispersive transport in disordered semiconductors:\ndepending on the interaction parameters it may range from a finite\nrenormalization of the diffusion coefficient to anomalous, subdiffusive\nbehavior. We make connections to recent experiments and discuss the\nimplications for future studies."
    },
    {
        "anchor": "Synchrotron X-Ray Reflectivity Study of the Adsorption Film of\n  Octadecanamide at the Toluene-Water Interface: The structure of an adsorption octadecanamide film at the planar\ntoluene-water interface is studied by X-ray reflectometry using synchrotron\nradiation with photon energy of 15 keV. The electron density (polarizability)\nprofiles, according to which the interface structure is determined by the pH\nlevel in the water subphase, are reconstructed from experimental data with the\nhelp of a model-independent approach. For a high pH~11, the adsorption film is\na crystalline octadecanamide monolayer with a thickness of about 2.6 nm, in\nwhich aliphatic tails of surfactant are extended along the normal to the\nsurface. For low pH ~ 2, the thickness of the surface structure consisting of\nthe crystalline monolayer directly on the toluene-water interface and a thick\nlayer of deposited octadecanamide micelles reaches about 50 nm. In our opinion,\nthe condensation of nonionogenic surfactant micelles for which the surface\nconcentration of the surfactant increases significantly is caused by a change\nin the polarization direction upon a decrease in the pH level in the electric\ndouble layer at the interface between the water subphase and the octadecanamide\nmonolayer. The shape of the reconstructed electron density profiles also\nindicates the existence of a plane of the closest approach of surfactant\nmicelles to the interface at a distance of about 7 nm from it.",
        "positive": "Adiabatic and irreversible classical discrete time crystals: We simulate the dynamics of paramagnetic colloidal particles that are placed\nabove a magnetic hexagonal pattern and exposed to an external field\nperiodically changing its direction along a control loop. The conformation of\nthree colloidal particles above one unit cell adiabatically responds with half\nthe frequency of the external field creating a time crystal at arbitrary low\nfrequency. The adiabatic time crystal occurs because of the non-trivial\ntopology of the stationary manifold. When coupling colloidal particles in\ndifferent unit cells, many body effects cause the formation of topologically\nisolated time crystals and dynamical phase transitions between different\nadiabatic reversible and non-adiabatic irreversible space-time-crystallographic\narrangements."
    },
    {
        "anchor": "MD simulations and continuum theory of partially fluidized shear\n  granular flows: We carry out a detailed comparison of soft particle molecular dynamics\nsimulations with the theory of partially fluidized shear granular flows. We\nverify by direct simulations a constitutive relation based on the separation of\nthe shear stress tensor into a fluid part proportional to the strain rate\ntensor, and a remaining solid part. The ratio of these two components is\ndetermined by the order parameter. Based on results of the simulations we\nconstruct the ``free energy'' function for the order parameter. We also present\nthe simulations of the stationary deep 2D granular flows driven by an upper\nwall and compare it with the continuum theory.",
        "positive": "Theory of mechanical unfolding of homopolymer globule: all-or-none\n  transition in force-clamp mode vs phase coexistence in position-clamp mode: Equilibrium mechanical unfolding of a globule formed by long flexible\nhomopolymer chain collapsed in a poor solvent and subjected to an extensional\nforce f (force-clamp mode) or extensional deformation D (position-clamp mode)\nis studied theoretically. Our analysis, like all previous analysis of this\nproblem, shows that the globule behaves essentially differently in two modes of\nextension. In the force-clamp mode, mechanical unfolding of the globule with\nincreasing applied force occurs without intramolecular microphase segregation,\nand at certain threshold value of the pulling force the globule unfolds as a\nwhole (\"all-or-none\" transition). The value of the threshold force and the\ncorresponding jump in the distance between the chain ends increase with a\ndeterioration of the solvent quality and/or with an increase in the degree of\npolymerization. In the position-clamp mode, the globule unfolding occurs via\nintramolecular microphase coexistence of globular and extended microphases\nfollowed by an abrupt unraveling transition. Reaction force in the microphase\nsegregation regime demonstrates an \"anomalous\" decrease with increasing\nextension. Comparison of deformation curves in force and position-clamp modes\ndemonstrates that at weak and strong extensions the curves for two modes\ncoincide, differences are observed in the intermediate extension range. Another\nunfolding scenario is typical for short globules: in both modes of extension\nthey unfold continuously, without jumps or intramolecular microphase\ncoexistence, by passing a sequence of uniformly elongated configurations."
    },
    {
        "anchor": "Error-in-constitutive-relation (ECR) framework for the characterization\n  of linear viscoelastic solids: We develop an error-in-constitutive-relation (ECR) approach toward the\nfull-field characterization of linear viscoelastic solids described within the\nframework of standard generalized materials. To this end, we formulate the\nviscoelastic behavior in terms of the (Helmholtz) free energy potential and a\ndissipation potential. Assuming the availability of full-field interior\nkinematic data, the constitutive mismatch between the kinematic quantities\n(strains and internal thermodynamic variables) and their ``stress''\ncounterparts (Cauchy stress tensor and that of thermodynamic tensions),\ncommonly referred to as the ECR functional, is established with the aid of\nLegendre-Fenchel gap functionals linking the thermodynamic potentials to their\nenergetic conjugates. We then proceed by introducing the modified ECR (MECR)\nfunctional as a linear combination between its ECR parent and the kinematic\ndata misfit, computed for a trial set of constitutive parameters. The\naffiliated stationarity conditions then yield two coupled evolution problems,\nnamely (i) the forward evolution problem for the (trial) displacement field\ndriven by the constitutive mismatch, and (ii) the backward evolution problem\nfor the adjoint field driven by the data mismatch. This allows us to establish\ncompact expressions for the MECR functional and its gradient with respect to\nthe viscoelastic constitutive parameters. For generality, the formulation is\nestablished assuming both time-domain (i.e. transient) and frequency-domain\ndata. We illustrate the developments in a two-dimensional setting by pursuing\nthe multi-frequency MECR reconstruction of (i) piecewise-homogeneous standard\nlinear solid, and (b) smoothly-varying Jeffreys viscoelastic material.",
        "positive": "A priori Determination of the Extensional Viscosity of Polymer Melts: The COMOFLO dynamic Monte Carlo algorithm is extended to enable the\nsimulation of steady-state extensional rheology of dense melts for the first\ntime ever. This significant advancement provides the ability to accurately\ncapture the extensional viscosity of entangled polymer melts from low\ndeformation rates, throughout the strain hardening regime, and into the region\nof viscosity thinning To do so, the purely extensional flow field associated\nwith a four roll mill experiment is implemented in three dimensions. Periodic\nboundary conditions exist in all directions to enable a uniform deformation\nrate throughout the simulation domain. As expected, the extensional viscosity\nis four times the zero shear viscosity at low deformation rates. As the\ndeformation rate increases, the extensional viscosity increases, plateaus, and\nthen decreases. The algorithm thus correctly captures the physics of polymer\nmelts in extensional flow in a fully a priori manner while providing\nsignificant computational advantages over molecular dynamics methods. Because\nthe technique is applicable to polydisperse systems, the ability to predict in\nan a priori manner both shear and elongational rheology for linear polymer\nmelts of arbitrary molecular weight distribution can now be considered a solved\nproblem."
    },
    {
        "anchor": "Superstructures par agr\u00e9gation contr\u00f4l\u00e9e de nanocollo\u00efdes:\n  caract\u00e9risation structurale par diffusion de neutrons aux petits angles et\n  simulation num\u00e9rique: The complexation of micelles or charged nanoparticles with neutral-charged\nblock copolymers in aqueous solutions leads to the formation of colloidal\nsuperstructures also termed 'colloidal complexes'. Their primary interest\nrelies in their monodispersity in size, and in their increased domain of\nstability. In this review, the structural characterization by dynamic light\nscattering, cryo-TEM, and small angle neutron scattering is presented. Small\nangle neutron scattering results have been analyzed using numerical simulations\n- Monte Carlo or reverse Monte Carlo (RMC). Such simulations are useful to show\nthe compatibility between different models of colloidal superstructures, and\nexperiment. Our results have allowed us to propose a generic structure of\ncomplex colloids, made of a dense core of interacting colloids, bridged by\npolyelectrolyte blocks, and a hydrated corona. We have shown that such\nsuperstructures are formed systematically in these systems, with either\nmicelles or nanoparticles, for different copolymers, and different charges. The\ntext is in French.",
        "positive": "Stress-Induced Dinoflagellate Bioluminescence at the Single Cell Level: One of the characteristic features of many marine dinoflagellates is their\nbioluminescence, which lights up nighttime breaking waves or seawater sliced by\na ship's prow. While the internal biochemistry of light production by these\nmicroorganisms is well established, the manner by which fluid shear or\nmechanical forces trigger bioluminescence is still poorly understood. We report\ncontrolled measurements of the relation between mechanical stress and light\nproduction at the single-cell level, using high-speed imaging of\nmicropipette-held cells of the marine dinoflagellate $Pyrocystis~lunula$\nsubjected to localized fluid flows or direct indentation. We find a\nviscoelastic response in which light intensity depends on both the amplitude\nand rate of deformation, consistent with the action of stretch-activated ion\nchannels. A phenomenological model captures the experimental observations."
    },
    {
        "anchor": "Under-liquid Self-Assembly of Submerged Buoyant Polymer Particles: The self-assembly of submerged cold-plasma-treated polyethylene beads is\nreported. The plasma-treated immersed millimetrically-sized polyethylene beads\nformed well-ordered 2D quasi-crystalline structures. The submerged floating of\nlight polyethylene beads is possible due to the energy gain achieved by the\nwetting of the high-energy plasma-treated polymer surface prevailing over the\nenergy loss due to the upward climb of the liquid over the beads. The capillary\nimmersion attraction force is responsible for the observed self-assembly. The\nobserved 2D quasi-crystalline structures demonstrate dislocations and point\ndefects. Mechanical vibration of self-assembled rafts built of polyethylene\nbeads leads to the healing of point defects. The immersion capillary lateral\nforce governs the self-assembly, whereas the elastic force is responsible for\nthe repulsion of polymer beads.",
        "positive": "Arrest of flow and emergence of activated processes at the glass\n  transition of a suspension of particles with hard sphere-like interactions: By combining aspects of the coherent and self intermediate scattering\nfunctions, measured by dynamical light scattering on a suspension of hard\nsphere-like particles, we show that the arrest of particle number density\nfluctuations spreads from the position of the main structure factor peak.\nTaking the velocity auto-correlation function into account we propose that as\ndensity fluctuations are arrested the system's ability to respond to diffusing\nmomentum currents is impaired and, accordingly, the viscosity increases. From\nthe stretching of the coherent intermediate scattering function we read a\nquantitative manifestation of the undissipated thermal energy, the source of\nthose, ergodicity restoring, processes that short-circuit the sharp transition\nto a perfect glass."
    },
    {
        "anchor": "Dynamic Monte Carlo simulation of coupled transport through a narrow\n  multiply-occupied pore: Dynamic Monte Carlo simulations are used to study coupled transport\n(co-transport) through sub-nanometer-diameter pores. In this classic\nHodgkin-Keynes mechanism, an ion species uses the large flux of an abundant ion\nspecies to move against its concentration gradient. The efficiency of\nco-transport is examined for various pore parameters so that synthetic\nnanopores can be engineered to maximize this effect. In general, the pore must\nbe narrow enough that ions cannot pass each other and the charge of the pore\nlarge enough to attract many ions so that they exchange momentum. Co-transport\nefficiency increases as pore length increases, but even very short pores\nexhibit co-transport, in contradiction to the usual perception that long pores\nare necessary. The parameter ranges where co-transport occurs is consistent\nwith current and near-future synthetic nanopore geometry parameters, suggesting\nthat co-transport of ions may be a new application of nanopores.",
        "positive": "Flux saturation length of sediment transport: Sediment transport along the surface drives geophysical phenomena as diverse\nas wind erosion and dune formation. The main length-scale controlling the\ndynamics of sediment erosion and deposition is the saturation length\n$L_\\mathrm{s}$, which characterizes the flux response to a change in transport\nconditions. Here we derive, for the first time, an expression predicting\n$L_\\mathrm{s}$ as a function of the average sediment velocity under different\nphysical environments. Our expression accounts for both the characteristics of\nsediment entrainment and the saturation of particle and fluid velocities, and\nhas only two physical parameters which can be estimated directly from\nindependent experiments. We show that our expression is consistent with\nmeasurements of $L_\\mathrm{s}$ in both aeolian and subaqueous transport regimes\nover at least five orders of magnitude in the ratio of fluid and particle\ndensity, including on Mars."
    },
    {
        "anchor": "On the contact area and mean gap of rough, elastic contacts: Dimensional\n  analysis, numerical corrections and reference data: The description of elastic, nonadhesive contacts between solids with\nself-affine surface roughness seems to necessitate knowledge of a large number\nof parameters. However, few parameters suffice to determine many important\ninterfacial properties as we show by combining dimensional analysis with\nnumerical simulations. This insight is used to deduce the pressure dependence\nof the relative contact area and the mean interfacial separation $\\Delta\n\\bar{u}$ and to present the results in a compact form. Given a proper unit\nchoice for pressure $p$, i.e., effective modulus $E^*$ times the\nroot-mean-square gradient $\\bar{g}$, the relative contact area mainly depends\non $p$ but barely on the Hurst exponent $H$ even at large $p$. When using the\nroot-mean-square height $\\bar{h}$ as unit of length, $\\Delta \\bar{u}$\nadditionally depends on the ratio of the height spectrum cutoffs at short and\nlong wavelengths. In the fractal limit, where that ratio is zero, solely the\nroughness at short wavelengths is relevant for $\\Delta \\bar{u}$. This limit,\nhowever, should not be relevant for practical applications. Our work contains a\nbrief summary of the employed numerical method Green's function molecular\ndynamics including an illustration of how to systematically overcome numerical\nshortcomings through appropriate finite-size, fractal, and discretization\ncorrections. Additionally, we outline the derivation of Persson theory in\ndimensionless units. Persson theory compares well to the numerical reference\ndata.",
        "positive": "A Gaussian model for the membrane of red blood cells with cytoskeletal\n  defects: We study a Gaussian model of the membrane of red blood cells: a \"phantom\"\ntriangular network of springs attached at its vertices to a fluid bilayer with\ncurvature elasticity and tension. We calculate its fluctuation spectrum and we\ndiscuss the different regimes and non-monotonic features, including the precise\ncrossover at the mesh size between the already known limits with two different\ntensions and the renormalisation of the bending rigidity at low wavevectors. We\nalso show that the non-diagonal correlations reveal, in \"dark field\", the\ncytoskeletal defects. As a first step toward a non-invasive defect\nspectroscopy, the specific case of lacking bonds is studied numerically and\nanalytically."
    },
    {
        "anchor": "Universality of the Plastic Instability in Strained Amorphous Solids: By comparing the response to external strains in metallic glasses and in\nLenard-Jones glasses we find a quantitative universality of the fundamental\nplastic instabilities in the athermal, quasistatic limit. Microscopically these\ntwo types of glasses are as different as one can imagine, the latter being\ndetermined by binary interactions, whereas the former by multiple interactions\ndue to the effect of the electron gas that cannot be disregarded. In spite of\nthis enormous difference the plastic instability is the same saddle-node\nbifurcation. As a result the statistics of stress and energy drops in the\nelasto-plastic steady state are universal, sharing the same system-size\nexponents.",
        "positive": "The Length Scales of Dynamic Heterogeneity: Results from Molecular\n  Dynamics Simulations: Over times shorter than that required for relaxation of enthalpy, a liquid\ncan exhibit striking heterogeneities. The picture of these heterogeneities is\ncomplex with transient patches of rigidity, irregular yet persistent,\nintersected by tendrils of mobile particles, flickering intermittently into new\nspatial patterns of motion and arrest. The study of these dynamic\nheterogeneities has, over the last 20 years, allowed us to characterize\ncooperative dynamics, to identify new strategies in controlling kinetics in\nglass-forming liquids and to begin to systematically explore the relationship\nbetween dynamics and structure that underpins the behaviour of amorphous\nmaterials. Computer simulations of the dynamics in atomic and molecular liquids\nhave played a dominant role in all of this progress. While some may be uneasy\nabout this reliance on modelling, it is unavoidable, given the amount of\nmicroscopic detail needed to characterize the dynamic heterogeneities. The\ncomplexities revealed by these simulations have called for new conceptual\ntools. In this essay, I have tried to provide the reader with a clear and\ncomplete account of how these tools have been developed in terms of the\nliterature on kinetic length scales in molecular dynamics simulations. Through\nthe `prism' of these length scales, this essay addresses the question what have\nwe learnt about dynamic heterogeneities from computer simulations?"
    },
    {
        "anchor": "Monomer Fluctuations and the Distribution of Residual Bond Orientations\n  in Polymer Networks: In the present work, four series of simulations are analyzed: entangled model\nnetworks of a) mono-disperse or b) poly-disperse weight distribution between\nthe crosslinks, c) non-entangled phantom model networks and d) non-entangled\nmodel networks with excluded volume interactions. Previous work on the average\nresidual bond orientations (RBO) of model networks [1] is extended to describe\nthe distribution of RBOs for the entangled networks of the present study. The\nphantom model can be used to describe the monomer fluctuations, average RBOs,\nand the distribution of RBOs in networks without entanglements and without\nexcluded volume. Monomer fluctuations in networks with excluded volume but\nwithout entanglements can be described if the phantom model is corrected by the\neffect of the incompletely screened excluded volume. It is shown that\nparameters of the tube model can be determined from monomer fluctuations in\npolymer networks and from the RBO. A scaling of the RBO $\\propto N^{-1/2}$ is\nobserved in both mono-disperse and poly-disperse entangled networks, while for\nall networks without entanglements an RBO $\\propto N^{-1}$ is found. The\ndistribution of the RBO of entangled samples can be described by assuming a\nnormal distribution of tube lengths that is broadened by local fluctuations in\ntube curvature. Both observables, monomer fluctuations and RBO, are in\nagreement with slip link or slip tube models [2] for networks and disagree with\nnetwork models that do not allow a sliding motion of the monomers along a\nconfining tube.",
        "positive": "Critical cavity in the stretched fluid studied using square-gradient\n  density-functional model with triple-parabolic free energy: The generic square-gradient density-functional model with triple-parabolic\nfree energy is used to study the stability of a cavity introduced into the\nstretched liquid. The various properties of the critical cavity, which is the\nlargest stable cavity within the liquid, are compared with those of the\ncritical bubble of the homogeneous bubble nucleation. It is found that the size\nof the critical cavity is always smaller than that of the critical bubble,\nwhile the work of formation of the former is always higher than the latter in\naccordance with the conjectures made by Punnathanam and Corti [J. Chem. Phys.\n{\\bf 119}, 10224 (2003)] deduced from the Lennard-Jones fluids. Therefore their\nconjectures about the critical cavity size and the work of formation would be\nmore general and valid even for other types of liquid such as metallic liquid\nor amorphous. However, the scaling relations they found for the critical cavity\nin the Lennard-Jones fluid are marginally satisfied only near the spinodal."
    },
    {
        "anchor": "Two-component electrolyte solutions with dipolar cations on a charged\n  electrode: Theory and computer simulations: The development of advanced electrochemical devices for energy conversion and\nstorage requires fine tuning of electrode reactions, which can be accomplished\nby altering the electrode/solution interface structure. Particularly, in case\nof an alkali-salt electrolyte the electric double layer (EDL) composition can\nbe managed by introducing organic cations (e.g. room temperature ionic liquid\ncations) that may possess polar fragments. To explore this approach, we develop\na theoretical model predicting the efficient replacement of simple (alkali)\ncations with dipolar (organic) ones within the EDL. For the typical values of\nthe molecular dipole moment ($2-4~D$) the effect manifests itself at the\nsurface charge densities higher than 30 $\\mu C/cm^2$. We show that the\npredicted behavior of the system is in qualitative agreement with the molecular\ndynamics simulation results.",
        "positive": "Transition from viscous to inertial regime in dense suspensions: Non-Brownian suspensions present a transition from Newtonian behavior in the\nzero-shear limit to a shear thickening behaviour at a large shear rate, none of\nwhich is clearly understood so far. Here, we carry out numerical simulations of\nsuch an athermal dense suspension under shear, at an imposed confining\npressure. This set-up is conceptually identical to the recent experiments of\nBoyer and co-workers [Phys. Rev. Lett. 107,188301 (2011)]. Varying the\ninterstitial fluid viscosities, we recover the Newtonian and Bagnoldian regimes\nand show that they correspond to a dissipation dominated by viscous and contact\nforces respectively. We show that the two rheological regimes can be unified as\na function of a single dimensionless number, by adding the contributions to the\ndissipation at a given volume fraction."
    },
    {
        "anchor": "Local structure-mobility relationships of confined fluids reverse upon\n  supercooling: We examine the structural and dynamic properties of confined binary\nhard-sphere mixtures designed to mimic realizable colloidal thin films. Using\ncomputer simulations, governed by either Newtonian or overdamped Langevin\ndynamics, together with other techniques including a Fokker-Planck\nequation-based method, we measure the position-dependent and average\ndiffusivities of particles along structurally isotropic and inhomogeneous\ndimensions of the fluids. At moderate packing fractions, local single-particle\ndiffusivities normal to the direction of confinement are higher in regions of\nhigh total packing fraction; however, these trends are reversed as the film is\nsupercooled at denser average packings. Auxiliary short-time measurements of\nparticle displacements mirror data obtained for experimental supercooled\ncolloidal systems. We find that average dynamics can be approximately predicted\nbased on the distribution of available space for particle insertion across\norders of magnitude in diffusivity regardless of the governing microscopic\ndynamics.",
        "positive": "Collective Charge Fluctuations in Single-Electron Processes on\n  Nano-Networks: Using numerical modeling we study emergence of structure and\nstructure-related nonlinear conduction properties in the self-assembled\nnanoparticle films. Particularly, we show how different nanoparticle networks\nemerge within assembly processes with molecular bio-recognition binding. We\nthen simulate the charge transport under voltage bias via single-electron\ntunnelings through the junctions between nanoparticles on such type of\nnetworks. We show how the regular nanoparticle array and topologically\ninhomogeneous nanonetworks affect the charge transport. We find long-range\ncorrelations in the time series of charge fluctuation at individual\nnanoparticles and of flow along the junctions within the network. These\ncorrelations explain the occurrence of a large nonlinearity in the simulated\nand experimentally measured current-voltage characteristics and non-Gaussian\nfluctuations of the current at the electrode."
    },
    {
        "anchor": "Solution landscapes of the diblock copolymer-homopolymer model under\n  two-dimensional confinement: We investigate the solution landscapes of the confined diblock copolymer and\nhomopolymer in two-dimensional domain by using the extended Ohta--Kawasaki\nmodel. The projected saddle dynamics method is developed to compute the saddle\npoints with mass conservation and construct the solution landscape by coupling\nwith downward/upward search algorithms. A variety of novel stationary solutions\nare identified and classified in the solution landscape, including Flower\nclass, Mosaic class, Core-shell class, and Tai-chi class. The relationships\nbetween different stable states are shown by either transition pathways\nconnected by index-1 saddle points or dynamical pathways connected by a\nhigh-index saddle point. The solution landscapes also demonstrate the\nsymmetry-breaking phenomena, in which more solutions with high symmetry are\nfound when the domain size increases.",
        "positive": "Liquid Crystals as Multifunctional Interfaces for Trapping and\n  Characterizing Microplastics: Identifying and removing microplastics (MPs) from the environment is a global\nchallenge. This study explores how the colloidal fraction of common MPs behave\nat aqueous interfaces of liquid crystal (LC) films. We observed polyethylene\n(PE) and polystyrene (PS) microparticles to be captured at the LC interface and\nexhibit distinct two-dimensional aggregation patterns. The addition of low\nconcentrations of surfactant (sodium dodecylsulfate (SDS)) was found to further\namplify the differences in PS/PE aggregation patterns, with PS changing from a\nlinear chain-like morphology to a singly dispersed state with increasing SDS\nconcentration and PE forming dense clusters at all SDS concentrations.\nStatistical characterization of assembly patterns using fractal geometric\ntheory-based machine learning and a deep learning image recognition model\nyielded highly accurate classification of PE vs PS (>99%). Additionally, by\nperforming feature importance analysis on our deep learning model, dense,\nmulti-branched assemblies were confirmed to be unique features of PE relative\nto PS. To obtain additional insight into the origin of these key features, we\nperformed microscopic characterization of LC ordering at the microparticle\nsurfaces. These observations led us to predict that both microparticle types\nshould generate LC-mediated interactions (due to elastic strain) with a dipolar\nsymmetry, a prediction consistent with the observed interfacial organization of\nPS but not PE. We conclude that the non-equilibrium organization of the PE\nmicroparticles arises from their polycrystalline nature, which leads to rough\nparticle surfaces and weakened LC elastic interactions and enhanced capillary\nforces. Overall, our results highlight the potential utility of LC interfaces\nfor surface-sensitive characterization of colloidal MPs."
    },
    {
        "anchor": "Force-dependent switch in protein unfolding pathways and transition\n  state movements: Although known that single domain proteins fold and unfold by parallel\npathways, demonstration of this expectation has been difficult to establish in\nexperiments. Unfolding rate, $k_\\mathrm{u}(f)$, as a function of force $f$,\nobtained in single molecule pulling experiments on src SH3 domain, exhibits\nupward curvature on a $\\log k_\\mathrm{u}(f)$ plot. Similar observations were\nreported for other proteins for the unfolding rate $k_\\mathrm{u}([C])$. These\nfindings imply unfolding in these single domain proteins involves a switch in\nthe pathway as $f$ or $[C]$ is increased from a low to a high value. We provide\na unified theory demonstrating that if $\\log k_\\mathrm{u}$ as a function of a\nperturbation ($f$ or $[C]$) exhibits upward curvature then the underlying\nenergy landscape must be strongly multidimensional. Using molecular simulations\nwe provide a structural basis for the switch in the pathways and dramatic\nshifts in the transition state ensemble (TSE) in src SH3 domain as $f$ is\nincreased. We show that a single point mutation shifts the upward curvature in\n$\\log k_\\mathrm{u}(f)$ to a lower force, thus establishing the malleability of\nthe underlying folding landscape. Our theory, applicable to any perturbation\nthat affects the free energy of the protein linearly, readily explains movement\nin the TSE in a $\\beta$-sandwich (I27) protein and single chain monellin as the\ndenaturant concentration is varied. We predict that in the force range\naccessible in laser optical tweezer experiments there should be a switch in the\nunfolding pathways in I27 or its mutants.",
        "positive": "Heating mechanism affects equipartition in a binary granular system: Two species of particles in a binary granular system typically do not have\nthe same mean kinetic energy, in contrast to the equipartition of energy\nrequired in equilibrium. We investigate the role of the heating mechanism in\ndetermining the extent of this non-equipartition of kinetic energy. In most\nexperiments, different species of particle are unequally heated at the\nboundaries. We show by event-driven simulations that this differential heating\nat the boundary influences the level of non-equipartition even in the bulk of\nthe system. This conclusion is fortified by studying a numerical model and a\nsolvable stochastic model without spatial degrees of freedom. In both cases,\neven in the limit where heating events are rare compared to collisions, the\neffect of the heating mechanism persists."
    },
    {
        "anchor": "Anomalous elasticity, fluctuations and disorder in elastic membranes: Motivated by a freely suspended graphene and polymerized membranes in soft\nand biological matter we present a detailed study of a tensionless elastic\nsheet in the presence of thermal fluctuations and quenched disorder. The\nmanuscript is based on an extensive draft dating back to 1993, that was\ncirculated privately. It presents the general theoretical framework and\ncalculational details of numerous results, partial forms of which have been\npublished in brief Letters (Le Doussal and Radzihovsky 1992). The experimental\nrealization of atom-thin graphene sheets has driven a resurgence in this\nfascinating subject, making our dated predictions and their detailed\nderivations timely. To this end we analyze the statistical mechanics of a\ngeneralized D-dimensional elastic \"membrane\" embedded in d dimensions using a\nself-consistent screening approximation (SCSA), that has proved to be\nunprecedentedly accurate in this system, exact in three complementary limits: d\n--> infinity, D --> 4, and D=d. Focusing on the critical \"flat\" phase, for a\nhomogeneous two-dimensional membrane embedded in three dimensions, we predict\nits universal length-scale dependent roughness, elastic moduli exponents, and a\nuniversal negative Poisson ratio of -1/3. We also extend these results to\nshort- and long-range correlated random heterogeneity, predicting a variety of\nglassy wrinkled membrane states. Finally, we also predict and analyze a\ncontinuous crumpling transition in a \"phantom\" elastic sheet. We hope that this\ndetailed presentation of the SCSA theory will be useful for further theoretical\ndevelopments and corresponding experimental investigations on freely suspended\ngraphene.",
        "positive": "Entropic elasticity and dynamics of the bacterial chromosome: a\n  simulation study: We study the compression and extension dynamics of a DNA-like polymer\ninteracting with non-DNA binding and DNA-binding proteins, by means of computer\nsimulations. The geometry we consider is inspired by recent experiments probing\nthe compressional elasticity of the bacterial nucleoid (DNA plus associated\nproteins), where DNA is confined into a cylindrical container and subjected to\nthe action of a \"piston\" - a spherical bead to which an external force is\napplied. We quantify the effect of steric interactions (excluded volume) on the\nforce-extension curves as the polymer is compressed. We find that\nnon-DNA-binding proteins, even at low densities, exert an osmotic force which\ncan be a lot larger than the entropic force exerted by the compressed DNA. The\ntrends we observe are qualitatively robust with respect to changes in protein\nsize, and are similar for neutral and charged proteins (and DNA). We also\nquantify the dynamics of DNA expansion following removal of the \"piston\": while\nthe expansion is well fitted by power laws, the apparent exponent depends on\nprotein concentration, and protein-DNA interaction in a significant way. We\nfurther highlight an interesting kinetic process which we observe during the\nexpansion of DNA interacting with DNA-binding proteins when the interaction\nstrength is intermediate: the proteins bind while the DNA is packaged by the\ncompression force, but they \"pop-off\" one-by-one as the force is removed,\nleading to a slow unzipping kinetics. Finally, we quantify the importance of\nsupercoiling, which is an important feature of bacterial DNA in vivo."
    },
    {
        "anchor": "Nematic and gas-liquid transitions for sticky rods on square and cubic\n  lattices: Using grand-canonical Monte Carlo simulations, we investigate the phase\ndiagram of hard rods of length $L$ with additional contact (sticky) attractions\non square and cubic lattices. The phase diagram shows a competition between\ngas-liquid and ordering transitions (which are of demixing type on the square\nlattice for $L \\ge 7$ and of nematic type on the cubic lattice for $L \\ge 5$).\nOn the square lattice, increasing attractions initially lead to a stabilization\nof the isotropic phase. On the cubic lattice, the nematic transition remains of\nweak first order upon increasing the attractions. In the vicinity of the\ngas-liquid transition, the coexistence gap of the nematic transition quickly\nwidens. These features are different from nematic transitions in the continuum.",
        "positive": "Ion specificity and anomalous electrokinetic effects in hydrophobic\n  nanochannels: We demonstrate with computer simulations that anomalous electrokinetic\neffects, such as ion specificity and non-zero zeta potentials for uncharged\nsurfaces, are generic features of electro-osmotic flow in hydrophobic channels.\nThis behavior is due to the stronger attraction of larger ions to the\n``vapour--liquid-like'' interface induced by a hydrophobic surface. An\nanalytical model involving a modified Poisson--Boltzmann description for the\nion density distributions is proposed, which allows the anomalous flow profiles\nto be predicted quantitatively. This description incorporates as a crucial\ncomponent an ion-size-dependent hydrophobic solvation energy. These results\nprovide an effective framework for predicting specific ion effects, with\nimportant implications for the modeling of biological problems."
    },
    {
        "anchor": "Dynamics of Fiberboids: Fiberboids are active filaments trapped at the interface of two phases, able\nof harnessing energy (and matter) fluxes across the interface in order to\nproduce a rolling-like self-propulsion. We discuss several table-top examples\nand develop the physical framework for understanding their complex dynamics. In\nspite of some specific features in the examples studied we conclude that the\nphenomenon of fiberboids is highly generic and robust across different\nmaterials, types of fluxes and timescales. Fiberboid motility should play a\nrole from the macroscopic realm down to the micro scale and, as recently\nhypothesized, possibly as a means of biological self-propulsion that has\nescaped previous attention.",
        "positive": "Density profiles of a colloidal liquid at a wall under shear flow: Using a dynamical density functional theory we analyze the density profile of\na colloidal liquid near a wall under shear flow. Due to the symmetries of the\nsystem considered, the naive application of dynamical density functional theory\ndoes not lead to a shear induced modification of the equilibrium density\nprofile, which would be expected on physical grounds. By introducing a\nphysically motivated dynamic mean field correction we incorporate the missing\nshear induced interparticle forces into the theory. We find that the shear flow\ntends to enhance the oscillations in the density profile of hard-spheres at a\nhard-wall and, at sufficiently high shear rates, induces a nonequilibrium\ntransition to a steady state characterized by planes of particles parallel to\nthe wall. Under gravity, we find that the center-of-mass of the density\ndistribution increases with shear rate, i.e., shear increases the potential\nenergy of the particles."
    },
    {
        "anchor": "Vortex synchronization in dry active matter: It was recently shown that dry active matter may form rotating vortices\naround circular obstacles. However, is lacking of a systematic study in the\nliterature. Here, we study how two such structures interact mainly as a\nfunction of the shortest distance between the obstacles. We find that, like the\nobservations of vortex formation in wet active matter, both vortices can\nsynchronize their rotations in either opposite or in the same direction; we\ncall such regimes antiferromagnetic or ferromagnetic, respectively. We show\nthat, for the antiferromagnetic case, both vortices keep their motion\ncorrelated by exchanging particles through the region in between them,\nsimilarly to a cog; on the other hand, for the ferromagnetic regime, the\nparticle exchange takes place above and below the vortices, as two opposite\nparticle currents appear, similarly to a belt wrapped around both and, driving\nthem through their edges.",
        "positive": "Dynamics of cylindrical droplets on flat substrate: Lattice Boltzmann\n  modeling versus simple analytic models: The steady state motion of cylindrical droplets under the action of external\nbody force is investigated both theoretically and via lattice Boltzmann\nsimulation. As long as the shape-invariance of droplet is maintained, the\ndroplet's center-of-mass velocity linearly scales with both the force density\nand the square of droplet radius. However, a non-linear behavior appears as the\ndroplet deformation becomes significant. This deformation is associated with\nthe drop elongation occurring at sufficiently high external forcing. Yet,\nindependent of either the force density or the droplet size, the center-of-mass\nvelocity is found to be linear in terms of the inverse of dynamic viscosity. In\naddition, it is shown that the energy is mainly dissipated in a region near the\nsubstrate particularly close to the three phase contact line. The total viscous\ndissipation is found to be proportional to both the square of force density and\nthe inverse of dynamic viscosity. Moreover, the dependence of the\ncenter-of-mass velocity on the equilibrium contact angle is investigated. A\nsimple analytic model is provided reproducing the observed behavior."
    },
    {
        "anchor": "Asymptotic Theory for Directed Transport of Suspended Ferromagnetic\n  Nanoparticles: Using the rigid dipole model, we study the translational and rotational\nmotions of single-domain fer-romagnetic nanoparticles in a dilute suspension\ninduced by the harmonically oscillating gradient magnetic field in the presence\nof a time-independent uniform magnetic field. Our approach is based on a set of\nthe first-order differential equations that describe the time dependencies of\nthe particle coordinate and mag-netization angle. We find the asymptotic\nsolutions of this set of equations at small and large times and, by applying\nthe matched asymptotic expansions for discrete times, derive analytical\nexpressions for the aver-age particle coordinate and velocity.",
        "positive": "Stretching Hookean ribbons Part II: from buckling instability to\n  far-from-threshold wrinkle pattern: We address the fully-developed wrinkle pattern formed upon stretching a\nHookean, rectangular-shaped sheet, when the longitudinal tensile load induces\ntransverse compression that far exceeds the stability threshold of a purely\nplanar deformation. At this \"far from threshold\" parameter regime, which has\nbeen the subject of the celebrated Cerda-Mahadevan (CM) model, the wrinkle\npattern expands throughout the length of the sheet and the characteristic\nwavelength of undulations is much smaller than its width. Employing Surface\nEvolver simulations over a range of sheet thicknesses and tensile loads we\nelucidate the theoretical underpinnings of the far-from-threshold framework in\nthis set-up. We show that the evolution of wrinkles comes in tandem with\ncollapse of transverse compressive stress, rather than vanishing transverse\nstrain, such that the stress field approaches asymptotically a compression-free\nlimit, describable by tension field theory. We compute the compression-free\nstress field by simulating a Hookean sheet that has finite stretching modulus\nbut no bending rigidity, and show that this singular limit encapsulates the\ngeometrical nonlinearity underlying the amplitude-wavelength ratio of wrinkle\npatterns in physical, highly bendable sheets, even though the actual strains\nmay be so small that the local mechanics is perfectly Hookean. Finally, we\nrevisit the balance of bending and stretching energies that gives rise to a\nfavorable wrinkle wavelength, and study the consequent dependence of the\nwavelength on the tensile load as well as the thickness and length of the\nsheet."
    },
    {
        "anchor": "Accurate freezing and melting equations for the Lennard-Jones system: Analyzing three approximate methods to locate liquid-solid coexistence in\nsimple systems, an observation is made that all of them predict the same\nfunctional dependence of the temperature on density at freezing and melting of\nthe conventional Lennard-Jones system. The emerging equations can be written as\n$T={\\mathcal A}\\rho^4+{\\mathcal B}\\rho^2$ in normalized units. We suggest to\ndetermine the values of the coefficients ${\\mathcal A}$ at freezing and melting\nfrom the high-temperature limit, governed by the inverse twelfth power\nrepulsive potential. The coefficients ${\\mathcal B}$ can be determined from the\ntriple point parameters of the LJ fluid. This produces freezing and melting\nequations which are exact in the high-temperature limit and at the triple\npoint, and show remarkably good agreement with numerical simulation data in the\nintermediate region.",
        "positive": "Effect of size of nanoparticles on the Wormlike micelle-nanoparticle\n  system: We investigate the effect of the size of nanoparticles on the behaviour of\nequilibrium polymers (Wormlike micelles) and nanoparticle system. The\nself-organised structures of nanoparticles in the system show a morphological\nchange from percolating networks to non-percolating clusters with an increase\nin the minimum approaching distance (EVP-excluded volume parameter) between\nnanoparticles and the equilibrium polymers. The shape of the nanoparticle\nclusters (nanorods, nanosheets, etc.) depends on the density of the polymer\nmatrix, irrespective of the size of nanoparticles. We show that with an\nincrease in the nanoparticle size, the value of EVP at which the nanoparticle\nstructure undergoes the morphological change shifts to lower values. We also\nreport that with the increase in nanoparticle size, the packing of\nnanoparticles decreases. Hence, they do not form a well-defined structure with\nnanoparticles of bigger size. This decrease in the packing is due to the\ndecrease in the surface to volume ratio which in turn decreases the surface\ninteractions."
    },
    {
        "anchor": "The role of pair correlation function in the dynamical transition\n  predicted by the mode coupling theory: In a recent study we have found that for a large number of systems the\nconfiguration entropy at pair level, $S_{c2}$, which is primarily determined by\nthe structural information, vanishes at the mode coupling transition\ntemperature $T_{c}$.\n  Thus it appears that the information of the transition temperature is\nembedded in the structure of the liquid. In order to investigate this we\ndescribe the dynamics of the system at the mean field level and using the\nconcepts of the dynamical density function theory show that the dynamics\ndepends only on the structure of the liquid. Thus this theory is similar in\nspirit to the microscopic MCT. However unlike microscopic MCT, which predicts a\nvery high transition temperature, the present theory predicts a transition\ntemperature which is similar to $T_{c}$. Thus our study reveals that the\ninformation of the mode coupling transition temperature is embedded in the\nstructure of the liquid.",
        "positive": "Pores in a two-dimensional network of DNA strands - computer simulations: Formation of random network of DNA strands is simulated on a two-dimensional\ntriangular lattice. We investigate the size distribution of pores in the\nnetwork. The results are interpreted within theory of percolation on Bethe\nlattice."
    },
    {
        "anchor": "Simple Model for Attraction between Like-Charged Polyions: We present a simple model for the possible mechanism of appearance of\nattraction between like charged polyions inside a polyelectrolyte solution. The\nattraction is found to be short ranged, and exists only in presence of\nmultivalent counterions. The attraction is produced by the correlations in the\ncondensed layers of counterions surrounding each polyion, and appears only if\nthe number of condensed counterions exceeds the threshold, $ n > Z/2 \\alpha $,\nwhere $\\alpha$ is the valence of counterions and $Z$ is the polyion charge.",
        "positive": "Weak dispersive forces between glass-gold macroscopic surfaces in\n  alcohols: In this work we concentrate on an experimental validation of the Lifshitz\ntheory for van der Waals and Casimir forces in gold-alcohol-glass systems. From\nthis theory weak dispersive forces are predicted when the dielectric properties\nof the intervening medium become comparable to one of the interacting surfaces.\nUsing inverse colloid probe atomic force microscopy dispersive forces were\nmeasured occasionally and under controlled conditions by addition of salt to\nscreen the electrostatic double layer force if present. The dispersive force\nwas found to be attractive, and an order of magnitude weaker than that in air.\nAlthough the theoretical description of the forces becomes less precise for\nthese systems even with full knowledge of the dielectric properties, we find\nstill our results in reasonable agreement with Lifshitz theory."
    },
    {
        "anchor": "Soft wetting and the Shuttleworth effect, at the crossroads between\n  thermodynamics and mechanics: Extremely compliant elastic materials, such as thin membranes or soft gels,\ncan be deformed when wetted by a liquid drop. It is commonly assumed that the\nsolid capillarity in \"soft wetting\" can be treated in the same manner as liquid\nsurface tension. However, the physical chemistry of a solid interface is itself\naffected by any distortion with respect to the elastic reference state. This\ngives rise to phenomena that have no counterpart in liquids: the mechanical\nsurface stress is different from the excess free energy in surface. Here we\npoint out some striking consequences of this \"Shuttleworth effect\" in the\ncontext of wetting on deformable substrates, such as the appearance of elastic\nsingularities and unconventional capillary forces. We provide a synthesis\nbetween different viewpoints on soft wetting (microscopic and macroscopic,\nmechanics and thermodynamics), and point out key open issues in the field.",
        "positive": "Tailoring Relaxation Time Spectrum in Soft Glassy Materials: Physical properties of out of equilibrium soft materials depend on time as\nwell as deformation history. In this work we propose to transform this major\nshortcoming into gain by applying controlled deformation field to tailor the\nrheological properties. We take advantage of the fact that deformation field of\na certain magnitude can prevent particles in an aging soft glassy material from\noccupying energy wells up to a certain depth, thereby populating only the\ndeeper wells. We employ two soft glassy materials with dissimilar\nmicrostructures and demonstrate that increase in strength of deformation field\nwhile aging leads to narrowing of spectrum of relaxation times. We believe\nthat, in principle, this philosophy can be universally applied to different\nkinds of glassy materials by changing nature and strength of impetus."
    },
    {
        "anchor": "Elastic Behavior of a Two-dimensional Crystal near Melting: Using positional data from video-microscopy we determine the elastic moduli\nof two-dimensional colloidal crystals as a function of temperature. The moduli\nare extracted from the wave-vector-dependent normal mode spring constants in\nthe limit $q\\to 0$ and are compared to the renormalized Young's modulus of the\nKTHNY theory. An essential element of this theory is the universal prediction\nthat Young's modulus must approach $16 \\pi$ at the melting temperature. This is\nindeed observed in our experiment.",
        "positive": "Curiosity-driven search for novel non-equilibrium behaviors: Exploring the spectrum of novel behaviors a physical system can produce can\nbe a labor-intensive task. Active learning is a collection of iterative\nsampling techniques developed in response to this challenge. However, these\ntechniques often require a pre-defined metric, such as distance in a space of\nknown order parameters, in order to guide the search for new behaviors. Order\nparameters are rarely known for non-equilibrium systems a priori, especially\nwhen possible behaviors are also unknown, creating a chicken-and-egg problem.\nHere, we combine active and unsupervised learning for automated exploration of\nnovel behaviors in non-equilibrium systems with unknown order parameters. We\niteratively use active learning based on current order parameters to expand the\nlibrary of known behaviors and then relearn order parameters based on this\nexpanded library. We demonstrate the utility of this approach in Kuramoto\nmodels of coupled oscillators of increasing complexity. In addition to\nreproducing known phases, we also reveal previously unknown behavior and the\nrelated order parameter."
    },
    {
        "anchor": "Self propelled particle transport in regular arrays of rigid asymmetric\n  obstacles: We report numerical results which show the achievement of net transport of\nself-propelled particles (SPP) in the presence of a two-dimensional regular\narray of convex, either symmetric or asymmetric, rigid obstacles. The repulsive\ninter-particle (soft disks) and particle-obstacle interactions present no\nalignment rule. We find that SPP present a vortex-type motion around convex\nsymmetric obstacles even in the absence of hydrodynamic effects. Such a motion\nis not observed for a single SPP, but is a consequence of the collective motion\nof SPP around the obstacles. An steady particle current is spontaneously\nestablished in an array of non-symmetric convex obstacle (which presents no\ncavity in which particles may be trapped in), and in the absence of an external\nfield. Our results are mainly a consequence of the tendency of the\nself-propelled particles to attach to solid surfaces.",
        "positive": "The effects of polydispersity and metastability on crystal growth\n  kinetics: We investigate the effect of metastable gas-liquid (G-L) separation on\ncrystal growth in a system of either monodisperse or slightly size-polydisperse\nsquare well particles, using a simulation setup that allows us to focus on the\ngrowth of a single crystal. Our system parameters are such that, inside the\nmetastable G-L binodal, a macroscopic layer of the gas phase \"coats\" the\ncrystal as it grows, consistent with experiment and theoretical free energy\nconsiderations. Crucially, the effect of this metastable G-L separation on the\ncrystal growth rate depends qualitatively on whether the system is\npolydisperse. We measure reduced polydispersity and qualitatively different\nlocal size ordering in the crystal relative to the fluid, proposing that the\nrequired fractionation is dynamically facilitated by the gas layer. Our results\nshow that polydispersity and metastability, both ubiquitous in soft matter,\nmust be considered in tandem if their dynamical effects are to be understood."
    },
    {
        "anchor": "Dynamical Crossover in Supercritical Water: Dynamical crossover in water is studied by means of computer simulation. The\ncrossover temperature is calculated from the behavior of velocity\nautocorrelation functions. The results are compared with experimental data. It\nis shown that the qualitative behavior of the dynamical crossover line is\nsimilar to the melting curve behavior. Importantly, the crossover line belongs\nto experimentally achievable $(P,T)$ region which stimulates the experimental\ninvestigation in this field.",
        "positive": "Osmotic compression of droplets of hard rods: A computer simulation\n  study: By means of computer simulations we study how droplets of hard, rod-like\nparticles optimize their shape and internal structure under the influence of\nthe osmotic compression caused by the presence of spherical particles that act\nas depletion agents. At sufficiently high osmotic pressures the rods that make\nup the drops spontaneously align to turn them into uniaxial nematic liquid\ncrystalline droplets. The nematic droplets or \"tactoids\" that are formed this\nway are not spherical but elongated, resulting from the competition between the\nanisotropic surface tension and the elastic deformation of the director field.\nIn agreement with recent theoretical predictions we find that sufficiently\nsmall tactoids have a uniform director field, whilst large ones are\ncharacterized by a bipolar director field. From the shape and director-field\ntransformation of the droplets we are able to estimate the surface anchoring\nstrength and an average of the elastic constants of the hard-rod nematic."
    },
    {
        "anchor": "Collective motion of cells crawling on a substrate: roles of cell shape\n  and contact inhibition: Contact inhibition plays a crucial role in the motility of cells, the process\nof wound healing, and the formation of tumors. By mimicking the mechanical\nmotion of calls crawling on a substrate using a pseudopod, we constructed a\nminimal model for migrating cells which gives rise to contact inhibition of\nlocomotion (CIL) naturally. The model cell consists of two disks, one in the\nfront (a pseudopod) and the other one in the back (cell body), connected by a\nfinitely extensible spring. Despite the simplicity of the model, the cells'\ncollective behavior is highly nontrivial, depending on the shape of cells and\nwhether CIL is enabled or not. Cells with a small front circle (i.e. a narrow\npseudopod) form immobile colonies. In contrast, cells with a large front circle\n(i.e. such as a lamellipodium) exhibit coherent migration without any explicit\nalignment mechanism being present in the model. This suggests that crawling\ncells often exhibit broad fronts because it helps them avoid clustering. Upon\nincreasing the density, the cells develop density waves which propagate against\nthe direction of cell migration and finally arrest at higher densities.",
        "positive": "Lift at low Reynolds number: Lift forces are widespread in hydrodynamics. These are typically observed for\nbig and fast objects, and are often associated with a combination of fluid\ninertia (i.e. large Reynolds numbers) and specific symmetry-breaking\nmechanisms. In contrast, the properties of viscosity-dominated (i.e. low\nReynolds numbers) flows make it more difficult for such lift forces to emerge.\nHowever, the inclusion of boundary effects qualitatively changes this picture.\nIndeed, in the context of soft and biological matter, recent studies have\nrevealed the emergence of novel lift forces generated by boundary softness,\nflow gradients and/or surface charges. The aim of the present review is to\ngather and analyse this corpus of literature, in order to identify and unify\nthe questioning within the associated communities, and pave the way towards\nfuture research."
    },
    {
        "anchor": "Novel force field of [Bmim][Nf$_2$T] and its tranferability in a mixture\n  with water: In this work, a new force field is presented for the ionic liquid\n1-butyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide, [Bmim][Nf$_2$T].\nAs a part of the \\epsilon force field, the acronym IL/\\epsilon is used to refer\nto this ionic liquid. This new force field reproduces the dielectric constant,\nthe density, and the entalphy of vaporization, with an error of less than 3%,\nbeing posible to generate new force fields for ionic liquids, based on the\nflexibility of the molecule. In addition, a study of the [Bmim][Nf$_2$T]-H$_2$O\nmixture is performed from pure IL to pure water, passing through various\nconcentrations.",
        "positive": "Toroidal hollow-core microcavities produced by self-rolling of strained\n  polymer bilayer films: Hollow-core toroidal micro-cavities are obtained by self-rolling of\ndouble-layer (polyvinyl pyridine/polystyrole) polymer films. Rolling of the\nbilayer is due to preferential swelling of the polyvinyl pyridine in water\nsolution of dodecyl benzene sulfonic acid. The tube formation proceeds from a\ncircular opening in the film made by photolithography or by mechanical\nscratching. The toroid equilibrium dimensions are determined by the balance of\nthe elastic energy relaxation via the film scrolling and the work of the\nin-plane stretching that is due to increasing radius of the toroid. The\nprincipal features of the micro-toroid formation process are captured by a\nsimple analytical model. The inner walls of the cavities can be made metal\ncoated. To this aim, the polymer bilayer can be metallized by vacuum sputtering\nprior to lithographic patterning and rolling of the bilayer. The toroids with\nmetallic inner surface are promising for the future research as IR-frequency\nrange resonators."
    },
    {
        "anchor": "Anomalous softness in amorphous matter in the reversible plastic regime: We study an integer automaton elasto-plastic model of an amorphous solid\nsubject to cyclic shear of amplitude $\\Gamma$. We focus on the reversible\nplastic regime at intermediate $\\Gamma_0<\\Gamma<\\Gamma_y$, where, after a\ntransient, the system settles into a periodic limit cycle with hysteretic,\ndissipative plastic events which repeat after an integer number of cycles. We\nstudy the plastic strain rate, $\\frac{d\\epsilon}{d\\gamma}$, (where $\\gamma$ is\nthe applied strain and $\\epsilon$ is the plastic strain) during the terminal\nlimit cycles and show that it consists of a creeping regime at low $\\gamma$\nwith very low $\\frac{d\\epsilon}{d\\gamma}$ followed by a sharp transition at a\ncharacteristic strain, $\\gamma_*$, and stress, $\\sigma_*$, to a flowing regime\nwith higher $\\frac{d\\epsilon}{d\\gamma}$. We show that while increasing $\\Gamma$\nabove $\\Gamma_0$ results in lower terminal ground state energy,\n$U_{\\text{min}}$, and a correspondingly narrower distribution of stresses, it,\nsurprisingly, results in lower $\\gamma_*$, and $\\sigma_*$. The stress\ndistribution, $P(\\sigma)$, also becomes skewed for $\\Gamma>\\Gamma_0$. That is,\nthe systems in the RPR are anomalously soft and mechanically polarized. We\nrelate this to an emergent characteristic feature in the stress distribution,\n$P(\\sigma)$, at a value, $\\sigma_0$, which is independent of $\\Gamma$ and show\nthat $\\sigma_0$ implies a relation between the $\\Gamma$ dependence of\n$\\sigma_*$, $\\gamma_*$, and the amplitude of plastic strain, $\\epsilon_p$. We\nshow that the onset of hysteresis is characterized by a power-law scaling,\nindicative of a second order transition with $\\epsilon_p\\propto\n(\\Gamma-\\Gamma_0)^{1.2\\pm0.1}$. We argue that $\\sigma_0$ and, correspondingly,\nthe onset of the RPR at $\\Gamma=\\Gamma_0$, is simply set by the so-called\nEshelby-stress. Furthermore, we show that cycling at $\\Gamma_0$ results in a\nmaximally hardened state.",
        "positive": "In-drop capillary spooling of spider capture thread inspires hybrid\n  fibers with mixed solid-liquid mechanical properties: An essential element in the web-trap architecture, the capture silk spun by\necribellate orb spiders consists of glue droplets sitting astride a silk\nfilament. Mechanically this thread presents a mixed solid-liquid behavior\nunknown to date. Under extension, capture silk behaves as a particularly\nstretchy solid, owing to its molecular nanosprings, but it totally switches\nbehavior in compression to now become liquid-like: It shrinks with no apparent\nlimit while exerting a constant tension. Here, we unravel the physics\nunderpinning the unique behavior of this \"liquid wire\" and demonstrate that its\nmechanical response originates in the shape-switching of the silk filament\ninduced by buckling within the droplets. Learning from this natural example of\ngeometry and mechanics, we manufactured programmable liquid wires that present\npreviously unidentified pathways for the design of new hybrid solid-liquid\nmaterials. This article is available in open access with supplementary\nmaterials on the PNAS website."
    },
    {
        "anchor": "Inverse design of self-folding 3D shells: Inverse design aims at the development of elementary building blocks that\norganize spontaneously into target shapes. In self-assembly, the blocks diffuse\nto their target position. Alternatively, recent experiments point to a more\nrobust process in which the shape is formed from the self-folding of a planar\ntemplate. To control the folding of templates with competing folded structures,\nwe propose the inclusion of bond specificity. We consider a template that can\nfold into an octahedron or a boat shell and find the minimal design capable of\ntargeting either shell or switching between the two through an external\nstimulus, adding a new dimension to the design of shape-changing materials.",
        "positive": "Disentangling boson peaks and Van Hove singularities in a model glass: Using the example of a two-dimensional macroscopic model glass in which the\ninterparticle forces can be precisely measured, we obtain strong hints for\nresolving a controversy concerning the origin of the anomalous enhancement of\nthe vibrational spectrum in glasses (boson peak). Whereas many authors\nattribute this anomaly to the structural disorder, some other authors claim\nthat the short-range order, leading to washed-out Van Hove singularities, would\ncause the boson-peak anomaly. As in our model system, the disorder-induced and\nshortrange--order-induced features can be completely separated, we are able to\ndiscuss the controversy about the boson peak in real glasses in a new light.\nOur findings suggest that the interpretation of the boson peak in terms of\nshort-range order only, might result from a coincidence of the two phenomena in\nthe materials studied. In general, as we show, the two phenomena both exist,\nbut are two completely separate entities."
    },
    {
        "anchor": "Disordered boundaries destroy bulk phase separation in scalar active\n  matter: We show that disordered boundaries destroy bulk phase separation in scalar\nactive systems in dimension $d<d_c=3$. This is in strong contrast with the\nequilibrium case where boundaries have no impact on the bulk of phase-separated\nsystems. The underlying mechanism is revealed by considering a localized\ndeformation of an otherwise flat wall, from which the case of a disordered\nboundary can be inferred. We find long-ranged correlations of the density field\nas well as a cascade of eddies which we show prevent bulk phase separation in\nlow enough dimensions. The results are derived for dilute systems as well as in\nthe presence of interactions, under the sole condition that the density field\nis the unique hydrodynamic mode. Our theoretical calculations are validated by\nnumerical simulations of microscopic active systems.",
        "positive": "Electromagnetic propulsion and separation by chirality of nanoparticles\n  in liquids: We introduce a new mechanism for the propulsion and separation by chirality\nof small ferromagnetic particles suspended in a liquid. Under the action of a\nuniform d.c. magnetic field H and an a.c. electric field E isomers with\nopposite chirality move in opposite directions. Such a mechanism could have a\nsignificant impact on a wide range of emerging technologies. The component of\nthe chiral velocity that is odd in H is found to be proportional to the\nintrinsic orbital and spin angular momentum of the magnetized electrons. This\neffect arises because a ferromagnetic particle responds to the applied torque\nas a small gyroscope."
    },
    {
        "anchor": "Giant deformations and soft-inflation in LCE balloons: We propose that ballooning can be controlled, enriched and amplified by using\nrubbery networks of aligned molecular rods known as liquid crystal elastomers\n(LCEs). Firstly, LCEs are promising artificial muscles, showing large\nspontaneous deformations in response to heat and light. In LCE balloons,\nspontaneous deformations can trigger classic ballooning, either as\nphase-separation (at constant volume) or a volume jump (at constant pressure),\nresulting in greatly magnified actuation strains. Secondly, even at constant\ntemperature, LCEs have unusual mechanics augmented by soft-modes of deformation\nin which the nematic director rotates within the elastomer. These soft modes\nenrich the mechanics of LCE balloons, which can also \"balloon\" between rotated\nand unrotated states, either during the classic instability, or as a separate\npre-cursor, leading to successive instabilities during inflation.",
        "positive": "Accurate determination of crystal structures based on averaged local\n  bond order parameters: Local bond order parameters based on spherical harmonics, also known as\nSteinhardt order parameters, are often used to determine crystal structures in\nmolecular simulations. Here we propose a modification of this method in which\nthe complex bond order vectors are averaged over the first neighbor shell of a\ngiven particle and the particle itself. As demonstrated using soft particle\nsystems, this averaging procedure considerably improves the accuracy with which\ndifferent crystal structures can be distinguished."
    },
    {
        "anchor": "Solitary and shock waves in discrete double power-law materials: A novel strongly nonlinear laminar metamaterial supporting new types of\nsolitary and shock waves with impact energy mitigating capabilities is\npresented. It consists of steel plates with intermittent polymer toroidal rings\nacting as strongly nonlinear springs with large allowable strain. Their\nforce-displacement relationship is described by the addition of two power-law\nrelationships resulting in a solitary wave speed and width depending on the\namplitude. This double nonlinearity allows splitting of an initial impulse into\ntwo separate strongly nonlinear solitary wave trains. Solitary and shock waves\nare observed experimentally and analyzed numerically in an assembly with Teflon\no-rings.",
        "positive": "Statistics of reversible bond dynamics observed in force-clamp\n  spectroscopy: We present a detailed analysis of two-state trajectories obtained from\nforce-clamp spectroscopy (FCS) of reversibly bonded systems. FCS offers the\nunique possibility to vary the equilibrium constant in two-state kinetics, for\ninstance the unfolding and refolding of biomolecules, over many orders of\nmagnitude due to the force dependency of the respective rates. We discuss two\ndifferent kinds of counting statistics, the event-counting usually employed in\nthe statistical analysis of two-state kinetics and additionally the so-called\ncycle-counting. While in the former case all transitions are counted,\ncycle-counting means that we focus on one type of transitions. This might be\nadvantageous in particular if the equilibrium constant is much larger or much\nsmaller than unity because in these situations the temporal resolution of the\nexperimental setup might not allow to capture all transitions of an\nevent-counting analysis. We discuss how an analysis of FCS data for complex\nsystems exhibiting dynamic disorder might be performed yielding information\nabout the detailed force-dependence of the transition rates and about the time\nscale of the dynamic disorder. In addition, the question as to which extent the\nkinetic scheme can be viewed as a Markovian two-state model is discussed."
    },
    {
        "anchor": "Dependence of the energies of fusion on the intermembrane separation:\n  optimal and constrained: We calculate the characteristic energies of fusion between planar bilayers as\nafunction of the distance between them, measured from the\nhydrophobic/hydrophilic interface of one of the two nearest, cis, leaves to the\nother. The two leaves of each bilayer are of equal composition; 0.6 volume\nfraction of a lamellar-forming amphiphile, such as dioleoylphosphatidylcholine,\nand 0.4 volume fraction of a hexagonal-forming amphiphile, such as\ndioleoylphosphatidylethanolamine. Self-consistent field theory is employed to\nsolve the model. We find that the largest barrier to fusion is that to create\nthe metastable stalk. This barrier is the smallest, about 14.6 $k_BT$, when the\nbilayers are at a distance about 20 percent greater than the thickness of a\nsingle leaf, a distance which would correspond to between two and three\nnanometers for typical bilayers. The very size of the protein machinery which\nbrings the membranes together can prevent them from reaching this optimum\nseparation. For even modestly larger separations, we find a linear rate of\nincrease of the free energy with distance between bilayers for the metastable\nstalk itself and for the barrier to the creation of this stalk. We estimate\nthese rates for biological membranes to be about 7.1 $k_BT$/nm and 16.7\n$k_BT$/nm respectively. The major contribution to this rate comes from the\nincreased packing energy associated with the hydrophobic tails. From this we\nestimate, for the case of hemagglutinin, a free energy of 38 k_BT for the\nmetastable stalk itself, and a barrier to create it of 73 k_BT. Such a large\nbarrier would require that more than a single hemagglutinin molecule be\ninvolved in the fusion process, as is observed.",
        "positive": "Nonlinear geometrically exact dynamics of fluid-conveying cantilevered\n  hard magnetic soft pipe with uniform and nonuniform magnetizations: It is generally acknowledged that a hanging cantilevered pipe conveying fluid\nbecomes unstable by flutter-type instability at a critical flow velocity;\nmoreover, the pipe undergoes periodic self-excited oscillations in the\npost-flutter region. Additionally, the critical flow velocity increases when\nthe magnetized pipe is exposed to an actuating parallel magnetic field. The\nquestion arises as to whether the actuating magnetic field leads to lessening\nthe oscillation amplitude of the system in the post-flutter region. To answer\nthe question, the nonlinear responses of a fluid-conveying cantilevered hard\nmagnetic soft pipe with uniform and nonuniform magnetizations under an\nactuating parallel magnetic field are examined. In the case of the nonuniform\nmagnetization, the mass density and elastic modulus of the pipe in addition to\nits residual magnetic flux density vary along its length. The mathematical\nformulation is constructed via a nonlinear geometrically exact model and is\nsolved by employing the Galerkin technique in conjunction with the Runge-Kutta\nfinite difference scheme. The numerical results are then analyzed to reveal the\nrole of magnetization in the magneto-hydro-elastic responses of the system in\nthe absence and presence of magnetic field."
    },
    {
        "anchor": "How adsorption influences DNA denaturation: The thermally induced denaturation of DNA in the presence of attractive solid\nsurface is studied. The two strands of DNA are modeled via two coupled flexible\nchains without volume interactions. If the two strands are adsorbed on the\nsurface, the denaturation phase-transition disappears. Instead, there is a\nsmooth crossover to a weakly naturated state. Our second conclusion is that\neven when the inter-strand attraction alone is too weak for creating a\nnaturated state at the given temperature, and also the surface-strand\nattraction alone is too weak for creating an adsorbed state, the combined\neffect of the two attractions can lead to a naturated and adsorbed state.",
        "positive": "Simple derivation of the first cumulant for the Rouse chain: A simple analytic expression for the first cumulant of the dynamic structure\nfactor of a polymer coil in the Rouse model is derived. The obtained formula is\nexact within the usual assumption of the continuum distribution of beads along\nthe chain. It reflects the contributions to the scattering of light or neutrons\nfrom both the internal motion of the polymer and its diffusion, and is valid in\nthe whole region of the wave-vector change at the scattering."
    },
    {
        "anchor": "Relaxation and Rheology in Dense Athermal Suspensions: We study relaxation and rheology of dense athermal suspensions of\nfrictionless particles close below the jamming density. Our key quantity, the\nrelaxation time---determined from the exponential decay of the energy after the\nshearing has suddenly been switched off---is argued to be a determining factor\nbehind the algebraic divergence of various quantities as the jamming density is\napproached from below. We also define and measure the ``dissipation time'',\nwhich is obtained directly in shearing simulations and find that it behaves\nsimilarly to the relaxation time. Comparing shear viscosity with the expression\nfor the dissipation time we identify a non-divergent factor that explains the\nneed for correction terms in the scaling analyses of the shear viscosity.",
        "positive": "Universality of liquid dynamics: We investigate the origin of the Stokes-Einstein relation in liquids. The\nhard-sphere dynamics is analyzed using a new measure of structural relaxation -\nthe minimum Euclidean distance between configurations of particles. It is shown\nthat the universal relation between the structural relaxation and diffusion in\nliquids is caused by the existence of one dominating length scale imposed by\nthe structural correlations and associated with de Gennes narrowing. We\ndemonstrate that this relation can be described by a model of independent\nrandom walkers under the single-occupancy constraint."
    },
    {
        "anchor": "Curvature effects in interfacial acidity of amphiphilic vesicles: We analyze the changes in the vicinal acidity (pH) at a spherical amphiphilic\nmembrane. The membrane is assumed to contain solvent accessible, embedded,\ndissociable, charge regulated moieties. Basing our approach on the linear\nDebye-H\\\"uckel as well as the non-linear Poisson-Boltzmann theory, together\nwith the general Frumkin-Fowler-Guggenheim adsorption isotherm model of the\ncharge regulation process, we analyse and review the dependence of the local pH\non the position, as well as bulk electrolyte concentration, bulk pH and\ncurvature of the amphiphilic single membrane vesicle. With appropriately chosen\nadsorption parameters of the charge regulation model, we find a good agreement\nwith available experimental data.",
        "positive": "Excitation of fountain and entrainment instabilities at the interface\n  between two viscous fluids using a beam of laser light: We report on two instabilities called viscous fountain and viscous\nentrainment triggered at the interface between two liquids by the action of\nbulk flows driven by a laser beam. These streaming flows are due to light\nscattering losses in turbid liquids, and can be directed either toward or\nforward the interface. We experimentally and numerically investigate these\ninterface instabilities and show that the height and curvature of the interface\ndeformation at the threshold and the jet radius after interface destabilization\nmainly depend on the waist of the laser beam. Analogies and differences between\nthese two instabilities are characterized."
    },
    {
        "anchor": "Relationship between Characteristic Lengths and Effective Saffman Length\n  in Colloidal Monolayers near a Water-Oil Interface: The hydrodynamic interactions (HIs) in colloidal monolayers are strongly\ninfluenced by the boundary conditions and can be directly described in terms of\nthe cross-correlated diffusion of the colloid particles. In this work, we\nexperimentally measured the cross-correlated diffusion in colloidal monolayers\nnear a water-oil inter-face. The characteristic lengths of the system were\nobtained by introducing an effec-tive Saffman length. The characteristic\nlengths of a particle monolayer near a water-oil interface were found to be\nanisotropic in the longitudinal and transverse directions. From these\ncharacteristic lengths, the master curves of cross-correlated diffusion are\nobtained, which universally describe the HIs near a liquid-liquid interface.",
        "positive": "Origins of barchan dune asymmetry: insights from numerical simulations: Barchan dunes --- crescent-shaped dunes that form in areas of unidirectional\nwinds and low sand availability --- commonly display an asymmetric shape, with\none limb extended downwind. Several factors have been identified as potential\ncauses for barchan dune asymmetry on Earth and Mars: asymmetric bimodal wind\nregime, topography, influx asymmetry and dune collision. However, the dynamics\nand potential range of barchan morphologies emerging under each specific\nscenario that leads to dune asymmetry are far from being understood. In the\npresent work, we use dune modeling in order to investigate the formation and\nevolution of asymmetric barchans. We find that a bimodal wind regime causes\nlimb extension when the divergence angle between primary and secondary winds is\nlarger than $90^{\\circ}$, whereas the extended limb evolves into a seif dune if\nthe ratio between secondary and primary transport rates is larger than 25%.\nCalculations of dune formation on an inclined surface under constant wind\ndirection also lead to barchan asymmetry, however no seif dune is obtained from\nsurface tilting alone. Asymmetric barchans migrating along a tilted surface\nmove laterally, with transverse migration velocity proportional to the slope of\nthe terrain. Limb elongation induced by topography can occur when a barchan\ncrosses a topographic rise. Furthermore, transient asymmetric barchan shapes\nwith extended limb also emerge during collisions between dunes or due to an\nasymmetric influx. Our findings can be useful for making quantitative inference\non local wind regimes or spatial heterogeneities in transport conditions of\nplanetary dune fields hosting asymmetric barchans."
    },
    {
        "anchor": "X-ray fluorescence spectroscopy from ions at charged vapor/water\n  interfaces: X-ray fluorescence spectra from monovalent ions (Cs+) that accumulate from\ndilute solutions to form an ion-rich layer near a charged Langmuir monolayer\nare presented. For the salt solution without the monolayer, the fluorescence\nsignals below the critical angle are significantly lower than the detection\nsensitivity and only above the critical angle signals from the bulk are\nobserved. In the presence of a monolayer that provides surface charges, strong\nfluorescence signals below the critical angle are observed. Ion density\naccumulated at the interface are determined from the fluorescence. The\nfluorescent spectra collected as a function of incident x-ray energy near the\nLIII edge yield the extended absorption spectra from the ions, and are compared\nto recent independent results. The fluorescence data from divalent Ba2+ with\nand without monolayer are also presented.",
        "positive": "Steady Microfluidic Measurements of Mutual Diffusion Coefficients of\n  Liquid Binary Mixtures: We present a microfluidic method leading to accurate measurements of the\nmutual diffusion coefficient of a liquid binary mixture over the whole solute\nconcentration range in a single experiment. This method fully exploits solvent\npervaporation through a poly(dimethylsiloxane) (PDMS) membrane to obtain a\nsteady concentration gradient within a microfluidic channel. Our method is\napplicable for solutes which cannot permeate through PDMS, and requires the\nactivity and the density over the full concentration range as input parameters.\nWe demonstrate the accuracy of our methodology by measuring the mutual\ndiffusion coefficient of the water (1) $+$ glycerol (2) mixture, from\nmeasurements of the concentration gradient using Raman confocal spectroscopy\nand the pervaporation-induced flow using particle tracking velocimetry."
    },
    {
        "anchor": "Perpendicular separations of a binary mixture under van der Waals\n  confinement: We investigated the dynamics of a binary mixture (water and epoxy resin)\nconfined within van der Waals (vdW) walls using molecular dynamics simulations.\nWe discovered a novel phenomenon named perpendicular separations of two phases\n(PSTP). In the initial stage, central water molecules diffused, subsequently\ncondensing symmetrically within the confinement's mid-plane. In the later\nstage, as water droplets nucleate and grow, the resin separates perpendicularly\ninto two films due to the action of bubblers and vdW walls, resulting in a\nhollow nanochannel. The mechanisms and conditions underlying PSTS are\ndiscussed. The results indicate that the concentration (C) of resin in the\nmiddle region is linearly decreased with temporal power and linearly decreased\nwith time in the very last stage. Our findings could shed light on the\nmanufacture of nanofilms and organic nanochannels, which could help advance\nbio-detection and energy fields.",
        "positive": "Knot complexity and the probability of random knotting: The probability of a random polygon (or a ring polymer) having a knot type\n$K$ should depend on the complexity of the knot $K$. Through computer\nsimulation using knot invariants, we show that the knotting probability\ndecreases exponentially with respect to knot complexity. Here we assume that\nsome aspects of knot complexity are expressed by the minimal crossing number\n$C$ and the aspect ratio $p$ of the tube length to the diameter of the {\\it\nideal knot} of $K$, which is a tubular representation of $K$ in its maximally\ninflated state."
    },
    {
        "anchor": "Charge and hydration structure of dendritic polyelectrolytes: molecular\n  simulations of polyglycerol sulphate: Macromolecules based on dendritic or hyperbranched polyelectrolytes have been\nemerging as high potential candidates for biomedical applications. Here we\nstudy the charge and solvation structure of dendritic polyglycerol sulphate\n(dPGS) of generations 0 to 3 in aqueous sodium chloride solution by\nexplicit-solvent molecular dynamics computer simulations. We characterize dPGS\nby calculating several important properties such as relevant dPGS radii,\nmolecular distributions, the solvent accessible surface area, and the partial\nmolecular volume. In particular, as the dPGS exhibits high charge\nrenormalization effects, we address the challenges of how to obtain a\nwell-defined effective charge and surface potential of dPGS for practical\napplications. We compare implicit- and explicit-solvent approaches in our\nall-atom simulations with the coarse-grained simulations from our previous\nwork. We find consistent values for the effective electrostatic size (i.e., the\nlocation of the effective charge of a Debye--H\\\"{u}ckel sphere) within all the\napproaches, deviating at most by the size of a water molecule. Finally, the\nexcess chemical potential of water insertion into dPGS and its thermodynamic\nsignature are presented and rationalized.",
        "positive": "Logical and information aspects in surface science: friction,\n  capillarity, and superhydrophobicity: Logical and information aspects of friction and wetting (including the\nadhesion, capillarity, and superhydrophobicity) are discussed. Friction\ninvolves paradoxes, such as the Painlev\\'e paradoxes of non-existence or\nnon-uniqueness of solutions in mechanical systems of rigid bodies with dry\nfriction. These paradoxes can be treated by introducing ternary logic with the\nthree basic states: rest-motion-undefined. When elastic deformation is\nintroduced, the paradoxical solutions correspond to frictional instabilities\nleading to rest-motion-unstable as three states of a system. The dynamic\nevolution of a frictional interface towards a limit cycle can be viewed as a\nprocess of erasing the information about the interface due to the\ninstabilities. Furthermore, while friction force is universal, it is not\ntreated as a fundamental force and can be considered as an epiphenomenon of\nvarious synergetic mechanisms. This further relates friction to other surface\neffects, including the capillarity, with its binary logic of wetting states and\na possibility of droplet computation for lab-on-a-chip microfluidic reactors.\nWe discuss the logical foundation of biomimetic superhydrophobic surface design\nand how it is different from the conventional design. Both friction and wetting\ncan be used for novel unconventional logical and computational devices."
    },
    {
        "anchor": "Anomalously Slow Domain Growth in Fluid Membranes with Asymmetric\n  Transbilayer Lipid Distribution: The effect of asymmetry in the transbilayer lipid distribution on the\ndynamics of phase separation in fluid vesicles is investigated numerically for\nthe first time. This asymmetry is shown to set a spontaneous curvature for the\ndomains that alter the morphology and dynamics considerably. For moderate\ntension, the domains are capped and the spontaneous curvature leads to\nanomalously slow dynamics, as compared to the case of symmetric bilayers. In\ncontrast, in the limiting cases of high and low tensions, the dynamics proceeds\ntowards full phase separation.",
        "positive": "Forced dynamic dewetting of structured surfaces: Influence of\n  surfactants: We analyse the dewetting of printing plates for gravure printing with\nwell-defined gravure cells. The printing plates were mounted on a rotating\nhorizontal cylinder that is half immersed in an aqueous solution of the anionic\nsurfactant sodium 1-decanesulfonate. The gravure plates and the presence of\nsurfactants serve as one example of a real-world dewetting situation. When\nrotating the cylinder, a liquid meniscus was partially drawn out of the liquid\nforming a dynamic contact angle at the contact line. The dynamic contact angle\nis decreased on a structured surface as compared to a smooth one. This is due\nto contact line pinning at the borders of the gravure cells. Additionally,\nsurfactants tend to decrease the dynamic receding contact angle. We consider\nthe interplay between these two effects. We compare the height differences of\nthe meniscus on the structured and unstructured area as function of dewetting\nspeeds. The height difference increases with increasing dewetting speed. With\nincreasing size of the gravure cells this height difference and the induced\nchanges in the dynamic contact angle increased. By adding surfactant, the\nheight difference and the changes in the contact angle for the same surface\ndecreased. We further note that although the liquid dewets the printing plates\nsome liquid is always left in the gravure cell. At high enough surfactant\nconcentrations or high enough dewetting speed, the dynamic contact angles in\nthe structured surface approach those in flat surfaces. We conclude that\nsurfactant reduces the influence of surface structure on dynamic dewetting."
    },
    {
        "anchor": "Time Dependence and Density Inversion in Simulations of Vertically\n  Oscillated Granular Layers: We study a layer of grains atop a plate which oscillates sinusoidally in the\ndirection of gravity, using three-dimensional, time-dependent numerical\nsolutions of continuum equations to Navier-Stokes order as well as hard-sphere\nmolecular dynamics simulations. For high accelerational amplitudes of the\nplate, the layer exhibits a steady-state \"density inversion\" in which a\nhigh-density portion of the layer is supported by a lower-density portion. At\nlow accelerational amplitudes, the layer exhibits oscillatory time dependence\nthat is strongly correlated to the motion of the plate. We show that continuum\nsimulations yield results consistent with molecular dynamics results in both\nregimes.",
        "positive": "Transitions between distinct compaction regimes in complexes of\n  multivalent cationic lipids and DNA: We use X-ray scattering and molecular simulations to investigate the\nstructural properties of complexes of multivalent cationic lipids and DNA\nmolecules. At low mole fraction of neutral lipids (NLs), $\\Phi_{\\rm NL}$, the\ncomplexes show dramatic DNA compaction down to essentially close packed DNA\narrays with a DNA interaxial spacing $d_{\\rm DNA}=25\\AA$. A gradual increase in\n$\\Phi_{\\rm NL}$ does not lead to a continuous increase in $d_{\\rm DNA}$ as\nobserved for DNA complexes of monovalent cationic lipids (CLs). Instead,\ndistinct spacing regimes exist, with sharp transitions between them. Three\npacking states have been identified: (i) close packed, (ii) condensed, but not\nclose packed, with $d_{\\rm DNA}=27-28\\AA$, and (iii) an expanded state, where\n$d_{\\rm DNA}$ increases gradually with $\\Phi_{\\rm NL}$. Based on our\nexperimental and computational results, we conclude that the DNA condensation\nis mediated by the multivalent cationic lipids, which assemble between the\nnegatively charged DNA rods. Quite remarkably, the computational results show\nthat the less tightly packed structure in regime (ii) is thermodynamically more\nstable than the close packed structure in regime (i). Accordingly, the constant\nDNA spacing observed in regime (ii) is attributed to lateral phase coexistence\nbetween this stable CL-DNA complex and neutral membranes. This finding may\nexplain the reduced transfection efficiency measured for such complexes:\nTransfection involves endosomal escape and disassembly of the complex, and\nthese processes are inhibited by the high thermodynamic stability. Our results,\nwhich demonstrate the existence of an inverse correlation between the stability\nand transfection activity of lamellar CL-DNA complexes are, therefore,\nconsistent with a recently proposed model of cellular entry."
    },
    {
        "anchor": "Interaction of the model alkyltrimethylammonium ions with alkali halide\n  salts: an explicit water molecular dynamics study: We present an explicit water molecular dynamics simulation of dilute\nsolutions of model alkyltrimethylammonium surfactant ions (number of methylene\ngroups in the tail is 3, 5, 8, 10, and 12) in mixture with NaF, NaCl, NaBr, and\nNaI salts, respectively. The SPC/E model is used to describe water molecules.\nResults of the simulation at 298 K are presented in the form of radial\ndistribution functions between nitrogen and carbon atoms of CH$_2$ groups on\nthe alkyltrimethylammonium ion, and the counterion species in the solution. The\nrunning coordination numbers between carbon atoms of surfactants and\ncounterions are also calculated. We show that I$^-$ counterion exhibits the\nhighest, and F$^-$ the lowest affinity to \"bind\" to the model surfactants. The\nresults are discussed in view of the available experimental and simulation data\nfor this and similar solutions.",
        "positive": "Scaling of complex polymers: new universality classes and beyond: We analyse scaling laws that govern macromolecules of different topology:\npolymer chains, homogeneous and miktoarm star polymers in a good solvent\npossibly constrained by a porous medium. The latter is modelled by\nlong-range-correlated disorder with a pair correlation function g(r) that\ndecays with a power law g(r) r^{-a} at large distances r. We show that this\ntype of disorder changes the universality class of the system. Within the\nframes of the field-theoretical renormalization group approach we obtain the\ncorresponding new universal critical exponents for systems of homogeneous and\nstar copolymers and discuss different consequences of the architecture\ndependent change of the scaling behaviour."
    },
    {
        "anchor": "Phototactic bioconvection with the effect of oblique collimated flux at\n  forward scattering algae suspension in rotating medium: The primary objective of this article is to explore how rotation influences\nthe initiation of phototactic bioconvection. This investigation is conducted\nthrough the application of linear stability theory to a suspension composed of\nforward-scattering phototactic algae. The suspension is uniformly exposed to\noblique collimated flux. The bioconvection phenomenon is characterized by an\nunstable disturbance mode that undergoes a transition from a stationary state\nto an oscillatory state as the Taylor number varies while keeping other\nparameters constant. Additionally, it is noteworthy that rotation of the system\nhas a substantial stabilizing effect on the suspension.",
        "positive": "Design of acoustic diffraction plates for manipulating ultrasound in\n  liquid Helium: Many experiments in liquid Helium, such as the optical imaging of exploding\nelectron bubbles, which enables research on individual particles under applied\nconditions, involve the usage of ultrasound generated by piezoelectric\ntransducers. Previous studies either use planar transducers, which limits the\nmaximum sound intensity and the spatial resolution, or curved transducers,\nwhich only allow observations at fixed foci and make it difficult to apply\nuniform electric fields. In this paper, we introduce the usage of acoustic\ndiffraction plates in liquid Helium to amplify ultrasonic pressure oscillations\nat an arbitrary set of primary foci coupled with large counts of secondary\nfoci, all of which can be freely moved around by changing the ultrasound\nfrequency. The frequency dependence also allows us to generate controlled\nFaraday instabilities at the surface, which enables the generation of\nmulti-electron bubbles with desired parameters."
    },
    {
        "anchor": "Force network analysis of jammed solids: Using a system of repulsive, soft particles as a model for a jammed solid, we\nanalyze its force network as characterized by the magnitude of the contact\nforce between two particles, the local contact angle subtended between three\nparticles, and the local coordination number. In particular, we measure the\nlocal contact angle distribution as a function of the magnitude of the local\ncontact force. We find the suppression of small contact angles for locally\nlarger contact forces, suggesting the existence of chain-like correlations in\nthe locally larger contact forces. We couple this information with a\ncoordination number-spin state mapping to arrive at a Potts spin model with\nfrustration and correlated disorder to draw a potential connection between\njammed solids (no quenched disorder) and spin glasses (quenched disorder). We\nuse this connection to measure chaos due to marginality in the jammed system.\nIn addition, we present the replica solution of the one-dimensional, long-range\nPotts glass as a potential toy building block for a jammed solid, where a sea\nof weakly interacting spins provide for long-range interactions along a\nchain-like backbone of more strongly interacting spins.",
        "positive": "Stress driven fractionalization of vacancies in regular packings of\n  elastic particles: Elucidating the interplay of defect and stress at the microscopic level is a\nfundamental physical problem that has strong connection with materials science.\nHere, based on the two-dimensional crystal model, we show that the instability\nmode of vacancies with varying size and morphology conforms to a common\nscenario. A vacancy under compression is fissioned into a pair of dislocations\nthat glide and vanish at the boundary. This neat process is triggered by the\nlocal shear stress around the vacancy. The remarkable fractionalization of\nvacancies creates rich modes of interaction between vacancies and other\ntopological defects, and provides a new dimension for mechanical engineering of\ndefects in extensive crystalline structures."
    },
    {
        "anchor": "Rectification of bipolar nanopores in multivalent electrolytes: effect\n  of charge inversion and strong ionic correlations: Bipolar nanopores have powerful rectification properties due to the asymmetry\nin the charge pattern on the wall of the nanopore. In particular, bipolar\nnanopores have positive and negative surface charges along the pore axis.\nRectification is strong if the radius of the nanopore is small compared to the\nscreening length of the electrolyte so that both cations and anions have\ndepletion zones in the respective regions. The depths of these depletion zones\nis sensitive to sign of the external voltage. In this work, we are interested\nin the effect of the presence of strong ionic correlations (both between ions\nand between ions and surface charge) due to the presence of multivalent ions\nand large surface charges. We show that strong ionic correlations cause leakage\nof the coions, a phenomenon that is absent in mean field theories. In this\nmodeling study, we use both the mean-field Poisson-Nernst-Planck (PNP) theory\nand a particle simulation method, Local Equilibrium Monte Carlo (LEMC), to show\nthat phenomena such as overcharging and charge inversion cannot be reproduced\nwith PNP, while LEMC is able to produce nonmonotonic dependence of currents and\nrectification as a function of surface charge strength.",
        "positive": "Computer simulations of polydisperse ER fluids in DID model: The theoretical investigations on electrorheological (ER) fluids are usually\nconcentrated on monodisperse systems. Real ER fluids must be polydisperse in\nnature, i.e., the suspended particles can have various sizes and/or different\ndielectric constants. An initial approach for these studies would be the\npoint-dipole (PD) approximation, which is known to err considerably when the\nparticles approach and finally touch due to multipolar interactions. In a\nrecent work, we proposed a dipole-induced-dipole (DID) model for computer\nsimulation of ER fluids, which was shown to be both more accurate than the PD\nmodel and easy to use. The DID model was applied to simulate the athermal\naggregation of particles in ER fluids and the aggregation time was found to be\nsignificantly reduced as compared to the PD model. In this work, we will report\nresults for the case when the dielectric contrasts of some particles can be\nnegative. In which case, the direction of the force is reversed. Moreover, the\ninclusion of DID force further complicates the results because the symmetry\nbetween positive and negative contrasts will be broken by the presence of\ndipole-induced interactions."
    },
    {
        "anchor": "Semiflexible polymer enclosed in a 3D compact domain: The conformational states of a semiflexible polymer enclosed in a volume\n$V:=\\ell^{3}$ are studied as stochastic realizations of paths using the\nstochastic curvature approach developed in [Rev. E 100, 012503 (2019)], in the\nregime whenever $3\\ell/\\ell_ {p}> 1$, where $\\ell_{p}$ is the persistence\nlength. The cases of a semiflexible polymer enclosed in a cube and sphere are\nconsidered. In these cases, we explore the Spakowitz-Wang type polymer shape\ntransition, where the critical persistence length distinguishes between an\noscillating and a monotonic phase at the level of the mean-square end-to-end\ndistance. This shape transition provides evidence of a universal signature of\nthe behavior of a semiflexible polymer confined in a compact domain.",
        "positive": "Universal scaling and characterisation of gelation in associative\n  polymer solutions: A Brownian dynamics algorithm is used to describe the static behaviour of\nassociative polymer solutions. Predictions for the fractions of stickers bound\nby intra-chain and inter-chain association, as a function of system parameters,\nsuch as the number of stickers, the number of monomers between stickers, the\nsolvent quality, and concentration are obtained. A systematic comparison with\nthe scaling relations predicted by the mean-field theory of Dobrynin\n(Macromolecules, 37, 3881, 2004) is carried out. Different regimes of scaling\nbehaviour are identified depending on the monomer concentration, the density of\nstickers on a chain, and the solvent quality for backbone monomers. Simulation\nresults validate the predictions of the mean-field theory across a wide range\nof parameter values in all the scaling regimes. The value of the des Cloizeaux\nexponent proposed by Dobrynin for sticky polymer solutions, is shown to lead to\na collapse of simulation data for all the scaling relations considered here.\nThree different signatures for the characterisation of gelation are identified,\nwith each leading to a different value of the concentration at the sol-gel\ntransition. The modified Flory-Stockmayer expression is found to be validated\nby simulations for all three gelation signatures. Simulation results confirm\nthe prediction of scaling theory for the gelation line that separates sol and\ngel phases, when the modified Flory-Stockmayer expression is used. Phase\nseparation is found to occur with increasing concentration for systems in which\nthe backbone monomers are under theta-solvent conditions, and is shown to\ncoincide with a breakdown in the predictions of scaling theory."
    },
    {
        "anchor": "Effective triplet interactions in nematic colloids: Three-body effective interactions emerging between parallel cylindrical rods\nimmersed in a nematic liquid crystals are calculated within the Landau-de\nGennes free energy description. Collinear, equilateral and midplane\nconfigurations of the three colloidal particles are considered. In the last two\ncases the effective triplet interaction is of the same magnitude and range as\nthe pair one.",
        "positive": "Contactless Interfacial Rheology: Probing Shear at Liquid-Liquid\n  Interfaces without an Interfacial Geometry via Fluorescence Microscopy: Interfacial rheology is important for understanding properties such as\nPickering emulsion or foam stability. Currently, the response is measured using\na probe directly attached to the interface. This can both disturb the interface\nand is coupled to flow in the bulk phase, limiting its sensitivity. We have\ndeveloped a contactless interfacial method to perform interfacial shear\nrheology on liquid/liquid interfaces with no tool attached directly to the\ninterface. This is achieved by shearing one of the liquid phases and measuring\nthe interfacial response via confocal microscopy. Using this method we have\nmeasured steady shear material parameters such as interfacial elastic moduli\nfor interfaces with solid-like behaviour and interfacial viscosities for\nfluid-like interfaces. The accuracy of this method has been verified relative\nto a double-wall ring geometry. Moreover, using our contactless method we are\nable to measure lower interfacial viscosities than those that have previously\nbeen reported using a double-wall ring geometry. A further advantage is the\nsimultaneous combination of macroscopic rheological analysis with microscopic\nstructural analysis. Our analysis directly visualizes how the interfacial\nresponse is strongly correlated to the particle surface coverage and their\ninterfacial assembly. Furthermore, we capture the evolution and irreversible\nchanges in the particle assembly that correspond with the rheological response\nto steady shear."
    },
    {
        "anchor": "An Opto-Electric Micropump for Saline Fluids: A novel method to pump fluid in lab on chip devices with velocities up to\ntens of micrometer per second is introduced. A focused laser beam locally heats\nup an electrolyte. A net charge tends to accumulate in the heat-absorbing area,\ndue to unequal tendencies of positive and negative ions to move in the presence\nof the temperature gradient. An external electric field then exerts a net force\non the accumulated charge and consequently on water. This causes flow of water,\nwith velocities up to tens of micrometer per second, for a simple NaCl+water\nsolution. The method lets us change direction and amount of fluid pumping,\nsimply by replacing the focal area.",
        "positive": "Columnar and lamellar phases in attractive colloidal systems: In colloidal suspensions, the competition between attractive and repulsive\ninteractions gives rise to a rich and complex phenomenology. Here, we study the\nequilibrium phase diagram of a model system using a DLVO interaction potential\nby means of molecular dynamics simulations and a thermodynamical approach. As a\nresult, we find tubular and lamellar phases at low volume fraction. Such\nphases, extremely relevant for designing new materials, may be not easily\nobserved in the experiments because of the long relaxation times and the\npresence of defects."
    },
    {
        "anchor": "The interplay between boundary conditions and flow geometries in shear\n  banding: hysteresis, band configurations, and surface transitions: We study shear banding flows in models of wormlike micelles or polymer\nsolutions, and explore the effects of different boundary conditions for the\nviscoelastic stress. These are needed because the equations of motion are\ninherently non-local and include ``diffusive'' or square-gradient terms. Using\nthe diffusive Johnson-Segalman model and a variant of the Rolie-Poly model for\nentangled micelles or polymer solutions, we study the interplay between\ndifferent boundary conditions and the intrinsic stress gradient imposed by the\nflow geometry. We consider prescribed gradient (Neumann) or value (Dirichlet)\nof the viscoelastic stress tensor at the boundary, as well as mixed boundary\nconditions in which an anchoring strength competes with the gradient\ncontribution to the stress dynamics. We find that hysteresis during shear rate\nsweeps is suppressed if the boundary conditions favor the state that is induced\nby the sweep. For example, if the boundaries favor the high shear rate phase\nthen hysteresis is suppressed at the low shear rate edges of the stress\nplateau. If the boundaries favor the low shear rate state, then the high shear\nrate band can lie in the center of the flow cell, leading to a three-band\nconfiguration. Sufficiently strong stress gradients due to curved flow\ngeometries, such as that of cylindrical Couette flow, can convert this to a\ntwo-band state by forcing the high shear rate phase against the wall of higher\nstress, and can suppress the hysteresis loop observed during a shear rate\nsweep.",
        "positive": "Simulation of grains in a vibrated U-tube without interstitial fluid: We present a computational study using Molecular Dynamics of the development\nof an accumulation of grains in one side of a two dimensional U-tube under\nvertical vibrations. Studying the evolution of the height difference between\nthe centers of mass of the branches of the tube, we found that it reaches a\nsaturation value after vibrating for some time. We obtain that this saturation\nvalue is the same if the simulation start with the arms leveled or with a large\ninitial height difference. We explore the effect of the width of the tube, the\ndensity of the grains and the coefficient of restitution between the grains and\nthe wall on the value of the saturation. We obtain a value of the width of the\ntube for which the saturation value reaches a maximum, and show that the\ntransport of grains between arms is favored for low grain densities and high\ngrain-wall restitution coefficient."
    },
    {
        "anchor": "Holographic characterization of imperfect colloidal spheres: We demonstrate precise measurements of the size and refractive index of\nindividual dimpled colloidal spheres using holographic characterization\ntechniques developed for ideal spheres.",
        "positive": "The hydrogen bond network of water supports propagating optical\n  phonon-like modes: The local structure of liquid water as a function of temperature is a source\nof intense research. This structure is intimately linked to the dynamics of\nwater molecules, which can be measured using Raman and infrared spectroscopies.\nThe assignment of spectral peaks depends on whether they are collective modes\nor single molecule motions. Vibrational modes in liquids are usually considered\nto be associated to the motions of single molecules or small clusters. Using\nmolecular dynamics simulations we find dispersive optical phonon-like modes in\nthe librational and OH stretching bands. We argue that on subpicosecond time\nscales these modes propagate through water's hydrogen bond network over\ndistances of up to two nanometers. In the long wavelength limit these optical\nmodes exhibit longitudinal-transverse splitting, indicating the presence of\ncoherent long range dipole-dipole interactions, as in ice. Our results indicate\nthe dynamics of liquid water have more similarities to ice than previously\nthought."
    },
    {
        "anchor": "Scalable fabrication of bijel films via continuous flow slit-coating: Nanocomposite membranes are an emerging filtration material in the production\nof clean water. Recently, the fabrication of porous nanocomposite membranes via\nsolvent transfer induced phase separation (STrIPS) was introduced. During\nSTrIPS, the phase separation of two immiscible liquids is arrested by the\nattachment of nanoparticles at the liquid-liquid interface, generating a porous\nparticle-stabilized membrane template. STrIPS nanocomposite membranes, however,\nhave so far only been produced as hollow fibers. To overcome this, we designed\na roll-to-roll (R2R)-process for the continuous fabrication of flat-sheet\nnanocomposite membranes via STrIPS. We produce the STrIPS membrane by printing\nthe membrane precursor on a carrier substrate. This allows for the continuous\ncollection of STrIPS membranes with control over the membrane dimensions.\nContact angle measurements elucidate the wetting dynamics of the STrIPS\nmembrane on the substrate. Furthermore, we demonstrate control over the\nmembrane pore structure by varying the precusor liquid composition and by\nchanging the particle modification and loading in the membrane. With this, the\nR2R-approach may stimulate further advancements in the fabrication of\nflat-sheet nanocomposite membranes via STrIPS.",
        "positive": "Guided accumulation of active particles by topological design of a\n  second-order skin effect: Collective guidance of out-of-equilibrium systems without using external\nfields is a challenge of paramount importance in active matter, ranging from\nbacterial colonies to swarms of self-propelled particles. Designing strategies\nto guide active matter and exploiting enhanced diffusion associated to its\nmotion will provide insights for application from sensing, drug delivery to\nwater remediation. However, achieving directed motion without breaking detailed\nbalance, for example by asymmetric topographical patterning, is challenging.\nHere we engineer a two-dimensional periodic topographical design with detailed\nbalance in its unit cell where we observe spontaneous particle edge guidance\nand corner accumulation of self-propelled particles. This emergent behaviour is\nguaranteed by a second-order non-Hermitian skin effect, a topologically robust\nnon-equilibrium phenomenon, that we use to dynamically break detailed balance.\nOur stochastic circuit model predicts, without fitting parameters, how guidance\nand accumulation can be controlled and enhanced by design: a device guides\nparticles more efficiently if the topological invariant characterizing it is\nnon-zero. Our work establishes a fruitful bridge between active and topological\nmatter, and our design principles offer a blueprint to design devices that\ndisplay spontaneous, robust and predictable guided motion and accumulation,\nguaranteed by out-of-equilibrium topology."
    },
    {
        "anchor": "Mapping between long-time molecular and Brownian dynamics: We use computer simulations to test a simple idea for mapping between\nlong-time self diffusivities obtained from molecular and Brownian dynamics. The\nstrategy we explore is motivated by the behavior of fluids comprising particles\nthat interact via inverse-power-law pair potentials, which serve as good\nreference models for dense atomic or colloidal materials. Based on our\nsimulation data, we present an empirical expression that semi-quantitatively\ndescribes the \"atomic\" to \"colloidal\" diffusivity mapping for inverse-power-law\nfluids, but also for model complex fluids with considerably softer\n(star-polymer, Gaussian-core, or Hertzian) interactions. As we show, the\nanomalous structural and dynamic properties of these latter ultrasoft systems\npose problems for other strategies designed to relate Newtonian and Brownian\ndynamics of hard-sphere-like particles.",
        "positive": "Active nematic-isotropic interfaces in channels: We use numerical simulations to investigate the hydrodynamic behavior of the\ninterface between nematic (N) and isotropic (I) phases of a confined active\nliquid crystal. At low activities, a stable interface with constant shape and\nvelocity is observed separating the two phases. For nematics in homeotropic\nchannels, the velocity of the interface at the NI transition increases from\nzero (i) linearly with the activity for contractile systems and (ii)\nquadratically for extensile ones. Interestingly, the nematic phase expands for\ncontractile systems while it contracts for extensile ones, as a result of the\nactive forces at the interface. Since both activity and temperature affect the\nstability of the nematic, for active nematics in the stable regime the\ntemperature can be tuned to observe static interfaces, providing an operational\ndefinition for the coexistence of active nematic and isotropic phases. At\nhigher activities, beyond the stable regime, an interfacial instability is\nobserved for extensile nematics. In this regime defects are nucleated at the\ninterface and move away from it. The dynamics of these defects is regular and\npersists asymptotically for a finite range of activities. We used an improved\nhybrid model of finite differences and lattice Boltzmann method with\nmulti-relaxation-time collision operator, the accuracy of which allowed us to\ncharacterize the dynamics of the distinct interfacial regimes."
    },
    {
        "anchor": "Intrinsically polar elastic metamaterials: The ability to design and fabricate materials with tailored mechanical\nproperties, combined with immunity to damage, is a frontier of materials\nengineering. For example, materials which are characterized by elastic\nproperties that depend on the position inside a medium are required in\napplications where structural stability has to be combined with a soft and\ncompliant surface, like in impact protection and cushioning. A gradient in the\nelastic properties can be built from a single material, varying gradually the\nbulk porosity of the material or its geometrical structure. However, if such a\ngradient is built into the material at production, damage or wearing over time\nmight expose unwanted elastic properties. Here, we implement a design principle\nfor a spatially inhomogeneous material based on topological band-theory for\nmechanical systems. The resulting inhomogeneity is stable against wearing and\neven cutting the material in half. We show how, by creating a periodic elastic\nmaterial with topological properties, one can create an intrinsically polar\nbehavior, where a face with a given surface normal is stiff while its opposing\nface is soft.",
        "positive": "Enhanced ordering in length-polydisperse carbon nanotube solutions at\n  high concentrations as revealed by small angle X-ray scattering: Carbon nanotubes (CNTs) are stiff, all-carbon macromolecules with diameters\nas small as one nanometer and few microns long. Solutions of CNTs in\nchlorosulfonic acid (CSA) follow the phase behavior of rigid rod polymers\ninteracting via a repulsive potential and display a liquid crystalline phase at\nsufficiently high concentration. Here, we show that small-angle X-ray\nscattering and polarized light microscopy data can be combined to characterize\nquantitatively the morphology of liquid crystalline phases formed in CNT\nsolutions at concentrations from 3 to 6.5 % by volume. We find that upon\nincreasing their concentration, CNTs self-assemble into a liquid crystalline\nphase with a pleated texture and with a large inter-particle spacing that could\nbe indicative of a transition to higher-order liquid crystalline phases. We\nexplain how thermal undulations of CNTs can enhance their electrostatic\nrepulsion and increase their effective diameter by an order of magnitude. By\ncalculating the critical concentration, where the mean amplitude of undulation\nof an unconstrained rod becomes comparable to the rod spacing, we find that\nthermal undulations start to affect steric forces at concentrations as low as\nthe isotropic cloud point in CNT solutions."
    },
    {
        "anchor": "Kinetics of isotropic to string-like phase switching in\n  electrorheological fluids of nanocubes: Applying an electric field to polarisable colloidal particles, whose\npermittivity differs from that of the dispersing medium, generates induced\ndipoles that promote the formation of string-like clusters and ultimately alter\nthe fluid mechanical and rheological properties. Complex systems of this kind,\nwhose electric-field-induced rheology can be manipulated between that of\nviscous and elastic materials, are referred to as electrorheological fluids. By\ndynamic Monte Carlo simulations, we investigate the dynamics of self-assembly\nof dielectric nanocubes upon application of an electric field. Switching the\nfield on induces in-particle dipoles and, at sufficiently large field\nintensity, leads to stringlike clusters of variable length across a spectrum of\nvolume fractions. The kinetics of switching from the isotropic to the\nstring-like state suggests the existence of two mechanisms, the first related\nto the nucleation of chains and the second to the competition between further\nmerging and separation. We characterise the transient unsteady state by\nfollowing the chain length distribution and analysing the probability of\ntransition of nanocubes from one chain to another over time. Additionally, we\nemploy passive microrheology to gain an insight into the effect of the electric\nfield on the viscoelastic response of our model fluid. Not only do we observe\nthat it becomes more viscoelastic in the presence of the field, but also that\nits viscoelasticity assumes an anisotropic signature, with both viscous and\nelastic moduli in planes perpendicular to the external field being larger than\nthose along it.",
        "positive": "Hierarchical structures for a robustness-oriented capacity design: In this paper, we study the response of 2D framed structures made of\nrectangular cells, to the sudden removal of columns. We employ a simulation\nalgorithm based on the Discrete Element Method, where the structural elements\nare represented by elasto-plastic Euler Bernoulli beams with\nelongation-rotation failure threshold. The effect of structural cell\nslenderness and of topological hierarchy on the dynamic residual strength after\ndamage $\\ROne$ is investigated. Topologically \\textit{hierarchical} frames have\na primary structure made of few massive elements, while \\textit{homogeneous}\nframes are made of many thin elements. We also show how $\\ROne$ depends on the\nactivated collapse mechanisms, which are determined by the mechanical hierarchy\nbetween beams and columns, i.e. by their relative strength and stiffness.\nFinally, principles of robustness-oriented capacity design which seem to be in\ncontrast to the conventional anti-seismic capacity design are addressed."
    },
    {
        "anchor": "Cross-stream migration of a Brownian droplet in a polymer solution under\n  Poiseuille flow: The migration of a Brownian fluid droplet in a parallel-plate microchannel\nwas investigated using dissipative particle dynamics computer simulations. In a\nNewtonian solvent, the droplet migrated toward the channel walls due to\ninertial effects at the studied flow conditions, in agreement with theoretical\npredictions and recent simulations. However, the droplet focused onto the\nchannel centerline when polymer chains were added to the solvent. Focusing was\ntypically enhanced for longer polymers and higher polymer concentrations with a\nnontrivial flow-rate dependence due to droplet and polymer deformability.\nBrownian motion caused the droplet position to fluctuate with a distribution\nthat primarily depended on the balance between inertial lift forces pushing the\ndroplet outward and elastic forces from the polymers driving it inward. The\ndroplet shape was controlled by the local shear rate, and so its average shape\ndepended on the droplet distribution.",
        "positive": "The physics of active polymers and filaments: Active matter agents consume internal energy or extract energy from the\nenvironment for locomotion and force generation. Already rather generic models,\nsuch as ensembles of active Brownian particles, exhibit phenomena, which are\nabsent at equilibrium, in particular motility-induced phase separation and\ncollective motion. Further intriguing nonequilibrium effects emerge in\nassemblies of bound active agents as in linear polymers or filaments. The\ninterplay of activity and conformational degrees of freedom gives rise to novel\nstructural and dynamical features of individual polymers as well as in\ninteracting ensembles. Such out-of-equilibrium polymers are an integral part of\nliving matter, ranging from biological cells with filaments propelled by motor\nproteins in the cytoskeleton, and RNA/DNA in the transcription process, to long\nswarming bacteria and worms such as Proteus mirabilis and Caenorhabditis\nelegans, respectively. Even artificial active polymers have been synthesized.\nThe emergent properties of active polymers or filaments depend on the coupling\nof the active process to their conformational degrees of freedom, aspects which\nare addressed in this article. The theoretical models for tangentially and\nisotropically self-propelled or active-bath driven polymers are presented, both\nin presence and absence of hydrodynamic interactions. The consequences for\ntheir conformational and dynamical properties are examined, emphasizing the\nstrong influence of the coupling between activity and hydrodynamic\ninteractions. Particular features of emerging phenomena, induced by steric and\nhydrodynamic interactions, are highlighted. Various important, yet\ntheoretically unexplored, aspects are featured and future challenges are\ndiscussed."
    },
    {
        "anchor": "One- and two-component bottle-brush polymers: simulations compared to\n  theoretical predictions: Scaling predictions and results from self-consistent field calculations for\nbottle-brush polymers with a rigid backbone and flexible side chains under good\nsolvent conditions are summarized and their validity and applicability is\nassessed by a comparison with Monte Carlo simulations of a simple lattice\nmodel. It is shown that under typical conditions, as they are also present in\nexperiments, only a rather weak stretching of the side chains is realized, and\nthen the scaling predictions based on the extension of the Daoud-Cotton blob\npicture are not applicable.\n  Also two-component bottle brush polymers are considered, where two types\n(A,B) of side chains are grafted, assuming that monomers of different kind\nrepel each other. In this case, variable solvent quality is allowed for, such\nthat for poor solvent conditions rather dense cylinder-like structures result.\nTheories predict ``Janus Cylinder''-type phase separation along the backbone in\nthis case. The Monte Carlo simulations, using the pruned-enriched Rosenbluth\nmethod (PERM) then are restricted to rather short side chain length.\nNevertheless, evidence is obtained that the phase separation between an A-rich\npart of the cylindrical molecule and a B-rich part can only occur locally. The\ncorrelation length of this microphase separation can be controlled by the\nsolvent quality. This lack of a phase transition is interpreted by an analogy\nwith models for ferromagnets in one space dimension.",
        "positive": "Influence of Wetting Properties on Diffusion in a Confined Fluid: We briefly discuss how the wetting properties of a fluid/solid interface can\nindirectly influence the diffusion properties of fluid confined between two\nsolid walls. This influence is related to the variability of the hydrodynamic\nboundary conditions at the interface, which correlates to the wetting\nproperties."
    },
    {
        "anchor": "Monte Carlo simulations of interfaces in polymer blends: We review recent simulation studies of interfaces between immiscible\nhomopolymer phases. Special emphasis is given to the presentation of efficient\nsimulation techniques and powerful methods of data analysis, such as the\nanalysis of capillary wave spectra. Possible reasons for polymer\nincompatibility and ways to relate model dependent interaction parameters to an\neffective Flory Huggins parameter are discussed. Various interfaces are then\nconsidered and characterised with respect to their microscopic structure and\nthermodynamic properties. In particular, interfaces between homopolymers of\nequal or disparate stiffness are studied, interfaces containing diblock\ncopolymers, and interfaces confined in thin films. The results are related to\nthe phase behaviour of ternary homopolymer/copolymer systems, and to wetting\ntransitions in thin films.",
        "positive": "Nucleation of frictional slip: A yielding or a fracture process?: The onset of frictional sliding between contacting bodies under shear load is\nnucleated by the quasi-static growth of localized slip patches. After reaching\na certain critical size, these patches become unstable and continue growing\ndynamically, eventually causing the sliding of the entire interface. Two\ndifferent theories have been used to compute the nucleation length of such\npatches depending on the dominant process driving their growth. If it is only\nthe yielding of contact asperities (large-scale yielding), a stress criterion\nis applied, based on linear stability analysis, whereas if fracture dominates,\nan energy criterion is applied, based on fracture mechanics and classical\nnucleation theory. Both approaches contain important underlying assumptions\nthat are well-suited to describe either one situation or the other. However,\nwhat happens in-between is not captured by any of them. In this work, we use\nnumerical simulations to study what is the dominant underlying process driving\nnucleation for different conditions of heterogeneity and what are the\nimplications for nucleation dynamics and the onset of frictional sliding. We\nshow that large frictional heterogeneities enable a transition from a\nyielding-driven nucleation phase to a fracture-driven one. This transition\noccurs only above a certain level of heterogeneity and can either be\nquasi-static (stable) or dynamic (unstable), depending on the correlation\nlength of frictional strength along the interface and the difference in\nstrength between the strongest and the weakest point (the amplitude). Unstable\ntransitions generate localized dynamic slip events, whose magnitude increases\nwith higher correlation length and decreases with larger amplitude. Our work\nsheds new light on the role of heterogeneity and fracture in the nucleation of\nfrictional slip, bridging the gap between the two main governing theories for\nnucleation."
    },
    {
        "anchor": "Effective interactions of colloids on nematic films: The elastic and capillary interactions between a pair of colloidal particles\ntrapped on top of a nematic film are studied theoretically for large\nseparations $d$. The elastic interaction is repulsive and of quadrupolar type,\nvarying as $d^{-5}$. For macroscopically thick films, the capillary interaction\nis likewise repulsive and proportional to $d^{-5}$ as a consequence of\nmechanical isolation of the system comprised of the colloids and the interface.\nA finite film thickness introduces a nonvanishing force on the system (exerted\nby the substrate supporting the film) leading to logarithmically varying\ncapillary attractions. However, their strength turns out to be too small to be\nof importance for the recently observed pattern formation of colloidal droplets\non nematic films.",
        "positive": "The emergence of Airy stress function in two-dimensional disordered\n  packings of particles: The packing of hard-core particles in contact with their neighbors offers the\nstatically determinate problem which allows analytical investigation of the\nstress tensor distribution. We construct the stress probability functional and\nderive the complete set of equations for the tensor components in\ntwo-dimensions."
    },
    {
        "anchor": "Water and Ice Dielectric Spectra Scaling at 0 \u00b0C: Dielectric spectra (10^4-10^11 Hz) of water and ice at 0 {\\deg}C are\nconsidered in terms of proton conductivity and compared to each other. In this\npicture, the Debye relaxations, centered at 1/{\\tau}_W ~ 20 GHz (in water) and\n1/{\\tau}_I ~ 5 kHz (in ice), are seen as manifestations of diffusion of\nseparated charges in the form of H3O+ and OH- ions. The charge separation\nresults from the self-dissociation of H2O molecules, and is accompanied by\nrecombination in order to maintain the equilibrium concentration, N. The charge\nrecombination is a diffusion-controlled process with characteristic lifetimes\nof {\\tau}_W and {\\tau}_I, for water and ice respectively. The static\npermittivity, {\\epsilon}(0), is solely determined by N. Both, N and\n{\\epsilon}(0), are roughly constant at the water-ice phase transition, and both\nincrease, due to a slowing down of the diffusion rate, as the temperature is\nlowered. The transformation of the broadband dielectric spectra at 0 {\\deg}C\nwith the drastic change from {\\tau}_W to {\\tau}_I is mainly due to an abrupt\n(by 0.4 eV) change of the activation energy of the charge diffusion.",
        "positive": "Shear unzipping of double stranded DNA: We propose a simple nonlinear scaler displacement model to calculate the\ndistribution of effect created by a shear stress on a double stranded DNA\n(dsDNA) molecule and the value of shear force $F_c$ which is required to\nseparate the two strands of a molecule. It is shown that as long as the force\npulls entire strand in the direction of its application the value of $F_c$\ndepends linearly on the length; the deviation from linear behaviour takes place\nwhen part of a strand moves in opposite direction under the influence of force\nacting on the other strand. The calculated values of $F_c$ as a function of\nlength of dsDNA molecules are in very good agreement with the experimental\nvalues of Hatch et al (Phys. Rev. E $\\bf 78$, 011920 (2008))."
    },
    {
        "anchor": "Bifurcations of buckled, clamped anisotropic rods and thin bands under\n  lateral end translations: Motivated by observations of snap-through phenomena in buckled elastic strips\nsubject to clamping and lateral end translations, we experimentally explore the\nmulti-stability and bifurcations of thin bands of various widths and compare\nthese results with numerical continuation of a perfectly anisotropic Kirchhoff\nrod. Our choice of boundary conditions is not easily satisfied by the\nanisotropic structures, forcing a cooperation between bending and twisting\ndeformations. We find that, despite clear physical differences between rods and\nstrips, a naive Kirchhoff model works surprisingly well as an organizing\nframework for the experimental observations. In the context of this model, we\nobserve that anisotropy creates new states and alters the connectivity between\nexisting states. Our results are a preliminary look at relatively unstudied\nboundary conditions for rods and strips that may arise in a variety of\nengineering applications, and may guide the avoidance of jump phenomena in such\nsettings. We also briefly comment on the limitations of current strip models.",
        "positive": "Bulk dynamics of Brownian hard disks: Dynamical density functional\n  theory versus experiments on two-dimensional colloidal hard spheres: Using dynamical density functional theory (DDFT), we theoretically study\nBrownian self-diffusion and structural relaxation of hard disks and compare to\nexperimental results on quasi two-dimensional colloidal hard spheres. To this\nend, we calculate the self and distinct van Hove correlation functions by\nextending a recently proposed DDFT-approach for three-dimensional systems to\ntwo dimensions. We find that the theoretical results for both self- and\ndistinct part of the van Hove function are in very good quantitative agreement\nwith the experiments up to relatively high fluid packing fractions of roughly\n0.60. However, at even higher densities, deviations between experiment and the\ntheoretical approach become clearly visible. Upon increasing packing fraction,\nin experiments the short-time self diffusive behavior is strongly affected by\nhydrodynamic effects and leads to a significant decrease in the respective\nmean-squared displacement. In contrast, and in accordance with previous\nsimulation studies, the present DDFT which neglects hydrodynamic effects, shows\nno dependence on the particle density for this quantity."
    },
    {
        "anchor": "Photocontrol of Protein Conformation in a Langmuir Monolayer: We report a method to control the conformation of a weak polyampholyte (the\nprotein $\\beta$-casein) in Langmuir monolayers by light, even though the\nprotein is not photosensitive. Our approach is to couple the monolayer state to\na photochemical reaction excited in the liquid subphase. The conformational\ntransition of the protein molecule is triggered through its sensitivity to a\nsubphase bulk field (pH in this study), changing in the course of the\nphotochemical process. Thus, reaction of photoaquation of the ferrocyanide ion,\nwhich increases the subphase pH from 7.0 to about 8.3, produces a change in the\nsurface monolayer pressure, $\\Delta\\Pi$, between -0.5 and +1.5 ${\\rm mN/m}$\n(depending on the surface concentration), signalling a conformational switch.\nThe approach proposed here can be used to selectively target and influence\ndifferent interfacial properties by light, without embedding photosensitisers\nin the matrix.",
        "positive": "Internal and surface waves in vibrofluidized granular materials: Role of\n  cohesion: Wave phenomena in vibrofluidized dry and partially wet granular materials\nconfined in a quasi-two-dimensional geometry are investigated with numerical\nsimulations considering individual particles as hard spheres. Short ranged\ncohesive interactions arising from the formation of liquid bridges between\nadjacent particles are modeled by changing the velocity dependent coefficient\nof restitution. Such a change effectively suppresses the formation of surface\nwaves, in agreement with previous experimental observations. The difference in\npattern creation arises from the suppressed momentum transfer due to wetting\nand it can be quantitatively understood from an analysis of binary impacts."
    },
    {
        "anchor": "Putting hydrodynamic interactions to work: tagged particle separation: Separation of magnetically tagged cells is performed by attaching markers to\na subset of cells in suspension and applying fields to pull from them in a\nvariety of ways. The magnetic force is proportional to the field gradient, and\nthe hydrodynamic interactions play only a passive, adverse role. Here we\npropose using a homogeneous rotating magnetic field only to make tagged\nparticles rotate, and then performing the actual separation by means of\nhydrodynamic interactions, which thus play an active role. The method, which we\nexplore here theoretically and by means of numerical simulations, lends itself\nnaturally to sorting on large scales.",
        "positive": "Weak solution of the Hele-Shaw problem: shocks and viscous fingering: In Hele-Shaw flows, boundaries between fluids develop unstable viscous\nfingers. At vanishing surface tension, the fingers further evolve to cusp-like\nsingularities. We show that the problem admits a {\\it weak solution} where\nshock fronts triggered by a singularity propagate together with a fluid. Shocks\nform a growing, branching tree of a mass deficit, and a line distribution of\nvorticity where pressure and velocity of the fluid have finite discontinuities.\nImposing that the flow remain curl-free at macroscale determines the shock\ngraph structure. We present a self-similar solution describing shocks emerging\nfrom a generic (2,3)-cusp singularity -- an elementary branching event."
    },
    {
        "anchor": "Large Scale Brownian Dynamics of Confined Suspensions of Rigid Particles: We introduce methods for large scale Brownian Dynamics (BD) simulation of\nmany rigid particles of arbitrary shape suspended in a fluctuating fluid. Our\nmethod adds Brownian motion to the rigid multiblob method at a cost comparable\nto the cost of deterministic simulations. We demonstrate that we can\nefficiently generate deterministic and random displacements for many particles\nusing preconditioned Krylov iterative methods, if kernel methods to efficiently\ncompute the action of the Rotne-Prager-Yamakawa (RPY) mobility matrix and it\n\"square\" root are available for the given boundary conditions. We address a\nmajor challenge in large-scale BD simulations, capturing the stochastic drift\nterm that arises because of the configuration-dependent mobility. Unlike the\nwidely-used Fixman midpoint scheme, our methods utilize random finite\ndifferences and do not require the solution of resistance problems or the\ncomputation of the action of the inverse square root of the RPY mobility\nmatrix. We construct two temporal schemes which are viable for large scale\nsimulations, an Euler-Maruyama traction scheme and a Trapezoidal Slip scheme,\nwhich minimize the number of mobility solves per time step while capturing the\nrequired stochastic drift terms. We validate and compare these schemes\nnumerically by modeling suspensions of boomerang shaped particles sedimented\nnear a bottom wall. Using the trapezoidal scheme, we investigate the\nsteady-state active motion in a dense suspensions of confined microrollers,\nwhose height above the wall is set by a combination of thermal noise and active\nflows. We find the existence of two populations of active particles, slower\nones closer to the bottom and faster ones above them, and demonstrate that our\nmethod provides quantitative accuracy even with relatively coarse resolutions\nof the particle geometry.",
        "positive": "Curvature generation in nematic surfaces: In recent years there has been a growing interest in the study of shape\nformation using modern responsive materials that can be preprogrammed to\nundergo spatially inhomogeneous local deformations. In particular, nematic\nliquid crystalline solids offer exciting possibilities in this context.\nConsiderable recent progress has been made in achieving a variety of shape\ntransitions in thin sheets of nematic solids by engineering isolated points of\nconcentrated Gaussian curvature using topological defects in the nematic\ndirector field across textured surfaces. In this paper, we consider ways of\nachieving shape transitions in thin sheets of nematic glass by generation of\nnon-localised Gaussian curvature in the absence of topological defects in the\ndirector field. We show how one can blueprint any desired Gaussian curvature in\na thin nematic sheet by controlling the nematic alignment angle across the\nsurface and highlight specific patterns which present feasible initial targets\nfor experimental verification of the theory."
    },
    {
        "anchor": "Electrostatic-driven Self-assembly of Janus-like Monolayer-protected\n  Metal Nanoclusters: The generation of controlled microstructures of functionalized nanoparticles\nhas been one of the crucial challenges in nanoscience and nanotechnology.\nEfforts have been made to tune ligand charge states that can affect the\naggregation propensity and modulate the self-assembled structures. In this\nwork, we modelled zwitterionic Janus-like monolayer ligand-protected metal\nnanoclusters (J-MPCs) and studied their self-assembly using atomistic molecular\ndynamics and advanced enhanced sampling simulations. The oppositely-charged\nligands functionalization on two hemispheres of a J-MPC elicits asymmetric\nsolvation, primarily driven by distinctive hydrogen bonding patterns in the\nligand-solvent interactions. Electrostatic interactions between the oppositely\ncharged residues in J-MPCs guide the formation of one-dimensional and ring-like\nself-assembled superstructures with molecular dipoles oriented in specific\npatterns. The pertinent atomistic insights into the intermolecular interactions\ngoverning the self-assembled structures of zwitterionic J-MPCs obtained from\nthis work can be used to design a general strategy to create tunable\nmicrostructures of charged MPCs.",
        "positive": "A Supersolid Skin Covering both Water and Ice: The mysterious nature and functionality of water and ice skins remain\nbaffling to the community since 1859 when Farady firstly proposed liquid skin\nlubricating ice. Here we show the presence of supersolid phase that covers both\nwater and ice using Raman spectroscopy measurements and quantum calculations.\nIn the skin of two molecular layers thick, molecular undercoordination shortens\nthe H-O bond by ~16% and lengthens the OH nonbond by ~25% through repulsion\nbetween electron pairs on adjacent O atoms, which depresses the density from\n0.92 for bulk ice to 0.75 gcm-3. The O:H-O cooperative relaxation stiffens the\nH-O stretching phonon from 3200/3150 cm-1 to the same value of 3450 cm-1 and\nraises the melting temperature of both skins by up to ~310 K. Numerical\nderivatives on the viscosity and charge accumulation suggests that the elastic,\npolarized, and thermally stable supersolid phase makes the ice frictionless and\nwater skin hydrophobic and ice like at room temperature."
    },
    {
        "anchor": "Sample-to-sample torque fluctuations in a system of coaxial randomly\n  charged surfaces: Polarizable randomly charged dielectric objects have been recently shown to\nexhibit long-range lateral and normal interaction forces even when they are\neffectively net neutral. These forces stem from an interplay between the\nquenched statistics of random charges and the induced dielectric image charges.\nThis type of interaction has recently been evoked to interpret measurements of\nCasimir forces in vacuo, where a precise analysis of such disorder-induced\neffects appears to be necessary. Here we consider the torque acting on a\nrandomly charged dielectric surface (or a sphere) mounted on a central axle\nnext to another randomly charged surface and show that although the resultant\nmean torque is zero, its sample-to-sample fluctuation exhibits a long-range\nbehavior with the separation distance between the juxtaposed surfaces and that,\nin particular, its root-mean-square value scales with the total area of the\nsurfaces. Therefore, the disorder-induced torque between two randomly charged\nsurfaces is expected to be much more pronounced than the disorder-induced\nlateral force and may provide an effective way to determine possible disorder\neffects in experiments, in a manner that is independent of the usual normal\nforce measurement.",
        "positive": "Modeling bacterial flagellar motor with new structure information:\n  Rotational dynamics of two interacting protein nano-rings: In this article, we develop a mathematical model for the rotary bacterial\nflagellar motor (BFM) based on the recently discovered structure of the stator\ncomplex (MotA$_5$MotB$_2$). The structure suggested that the stator also\nrotates. The BFM is modeled as two rotating nano-rings that interact with each\nother. Specifically, translocation of protons through the stator complex drives\nrotation of the MotA pentamer ring, which in turn drives rotation of the FliG\nring in the rotor via interactions between the MotA ring of the stator and the\nFliG ring of the rotor. Preliminary results from the structure-informed model\nare consistent with the observed torque-speed relation. More importantly, the\nmodel predicts distinctive rotor and stator dynamics and their load dependence,\nwhich may be tested by future experiments. Possible approaches to verify and\nimprove the model to further understanding of the molecular mechanism for\ntorque generation in BFM are also discussed."
    },
    {
        "anchor": "Fragmentation and Limits to Dynamical Scaling in Viscous Coarsening: An\n  Interrupted in situ X-Ray Tomographic Study: X-Ray microtomography was used to follow the coarsening of the structure of a\nternary silicate glass experiencing phase separation in the liquid state. The\nvolumes, surfaces, mean and Gaussian curvatures of the domains of minority\nphase were measured after reconstruction of the 3D images and segmentation. A\nlinear growth law of the characteristic length scale $\\ell \\sim t$ was\nobserved. A detailed morphological study was performed. While dynamical scaling\nholds for most of the geometrical observables under study, a progressive\ndeparture from scaling invariance of the distributions of local curvatures was\nevidenced. The latter results from a gradual fragmentation of the structure in\nthe less viscous phase that also leads to a power-law size distribution of\nisolated domains.",
        "positive": "A simple theory for interfacial properties of dilute solutions: Recent studies suggest that cosolute mixtures may exert significant\nnon-additive effects upon protein stability. The corresponding liquid-vapor\ninterfaces may provide useful insight into these non-additive effects.\nAccordingly, in this work we relate the interfacial properties of dilute\nmulticomponent solutions to the interactions between solutes. We first derive a\nsimple model for the surface excess of solutes in terms of thermodynamic\nobservables. We then develop a lattice-based statistical mechanical\nperturbation theory to derive these observables from microscopic interactions.\nRather than adopting a random mixing approximation, this dilute solution theory\n(DST) exactly treats solute-solute interactions to lowest order in perturbation\ntheory. Although it cannot treat concentrated solutions, Monte Carlo (MC)\nsimulations demonstrate that DST describes dilute solutions with much greater\naccuracy than regular solution theory. Importantly, DST emphasizes an important\ndistinction between the `intrinsic' and `effective' preferences of solutes for\ninterfaces. DST predicts that three classes of solutes can be distinguished by\ntheir intrinsic preference for interfaces. While the surface preference of\nstrong depletants are relatively insensitive to interactions, the surface\npreference of strong surfactants can be modulated by interactions at the\ninterface. Moreover, DST predicts that the surface preference of weak\ndepletants and weak surfactants can be qualitatively inverted by interactions\nin the bulk. We also demonstrate that DST can be extended to treat surface\npolarization effects and to model experimental data. MC simulations validate\nthe accuracy of DST predictions for lattice systems that correspond to molar\nconcentrations."
    },
    {
        "anchor": "Nonlinear plastic modes in disordered solids: We propose a framework within which a robust mechanical definition of\nprecursors to plastic instabilities, often termed `soft-spots', naturally\nemerges. They are shown to be collective displacements (modes) $\\hat{z}_0$ that\ncorrespond to local minima of the `barrier function' $b(\\hat{z})$. The latter\nis derived from the cubic approximation of the variation $\\delta\nU_{\\hat{z}}(s)$ of the potential energy upon displacing particles a distance\n$s$ along $\\hat{z}$. We show that modes $\\hat{z}_0$ corresponding to low-lying\nminima of $b(\\hat{z})$ lead to transitions over energy barriers in the glass,\nand are therefore associated with highly asymmetric variations $\\delta\nU_{\\hat{z}}(s)$ with $s$. We further demonstrate how a heuristic search for\nlocal minima of $b(\\hat{z})$ can a-priori detect the locus and geometry of\nimminent plastic instabilities with remarkable accuracy, at strains as large as\n$\\gamma_c-\\gamma \\sim 10^{-2}$ away from the instability strain $\\gamma_c$,\nwhere the non-affine displacements under shear are still largely delocalized.\nOur findings suggest that the a-priori detection of plastic instabilities can\nbe effectively carried out by the investigation of the landscape of\n$b(\\hat{z})$.",
        "positive": "Non-Gaussian polymers described by alpha-stable chain statistics: model,\n  applications and effective interactions in binary mixtures: The Gaussian chain model is the classical description of a polymeric chain,\nwhich provides the analytical results regarding end-to-end distance, the\ndistribution of segments around the mass center of a chain, coarse grained\ninteractions between two chains and effective interactions in binary mixtures.\nThis hierarchy of results can be calculated thanks to the alpha stability of\nthe Gaussian distribution. In this paper we show that it is possible to\ngeneralize the model of Gaussian chain to the entire class of alpha stable\ndistributions, obtaining the analogous hierarchy of results expressed by the\nanalytical closed-form formulas in the Fourier space. This allows us to\nestablish the alpha-stable chain model. We begin with reviewing the\napplications of Levy flights in the context of polymer sciences, which include:\nchains with heavy-tailed distributions of persistence length, polymers adsorbed\nto the surface and the chains driven by a noise with power-law spatial\ncorrelations. Further, we derive the distribution of segments around the mass\ncenter of the alpha-stable chain and the coarse-grained interaction potential\nbetween two chains is constructed. These results are employed to discuss the\nmodel of binary mixture consisting of the alpha-stable chains. On what follows,\nwe establish the spinodal decomposition condition generalized to the particles\ndescribed by the shape of alpha-stable distributions. This condition is finally\napplied to analyze the on-surface phase separation of adsorbed polymers, which\nare known to be described with heavy tailed statistics."
    },
    {
        "anchor": "Crossover from viscous fingering to fracturing in cohesive wet granular\n  media: a photoporomechanics study: We study fluid-induced deformation and fracture of cohesive granular media,\nand apply photoporomechanics to uncover the underpinning grain-scale mechanics.\nWe fabricate photoelastic spherical particles of diameter d=2mm, and make a\nmonolayer granular pack with tunable intergranular cohesion in a circular\nHele-Shaw cell that is initially filled with viscous silicone oil. We inject\nwater into the oil-filled photoelastic granular pack, varying the injection\nflow rate, defending-fluid viscosity, and intergranular cohesion. We find two\ndifferent modes of fluid invasion: viscous fingering, and fracturing with\nleak-off of the injection fluid. We directly visualize the evolving effective\nstress field through the particles' photoelastic response, and discover a hoop\neffective stress region behind the water invasion front, where we observe\ntensile force chains in the circumferential direction. Outside the invasion\nfront, we observe compressive force chains aligning in the radial direction. We\nconceptualize the system's behavior by means of a two-phase poroelastic\ncontinuum model. The model captures granular pack dilation and compaction with\nthe boundary delineated by the invasion front, which explains the observed\ndistinct alignments of the force chains. Finally, we rationalize the crossover\nfrom viscous fingering to fracturing by comparing the competing forces behind\nthe process: viscous force from fluid injection that drives fractures, and\nintergranular cohesion and friction that resist fractures.",
        "positive": "The break-up of free films pulled out of a pure liquid bath: In this paper, we derive a lubrication model to describe the non-stationary\nfree liquid film that is created when a vertical frame is pulled out of a\nliquid reservoir at a given velocity. We here focus on the case of a pure\nliquid, corresponding to a stress-free boundary condition at the liquid/air\ninterfaces of the film, and thus employ an essentially extensional description\nof the flow. Taking into account van der Waals interactions between the\ninterfaces, we observe that film rupture is well-defined in time as well as in\nspace, which allows us to compute the critical thickness and the film height at\nthe moment of rupture. The theoretical predictions of the model turn out to be\nin quantitative agreement with experimental measurements of the break-up height\nof silicone oil films in a wide range of pulling velocities and supporting\nfiber diameters."
    },
    {
        "anchor": "Optical Tweezers as a Micromechanical Tool for Studying Defects in 2D\n  Colloidal Crystals: This paper reports on some new results from the analyses of the video\nmicroscopy data obtained in a prior experiment on two-dimensional (2D)\ncolloidal crystals. It was reported previously that optical tweezers can be\nused to create mono- and di-vacancies in a 2D colloidal crystal. Here we report\nthe results on the creation of a vacancy-interstitial pair, as well as\ntri-vacancies. It is found that the vacancy-interstitial pair can be\nlong-lived, but they do annihilate each other. The behavior of tri-vacancies is\nmost intriguing, as it fluctuates between a configuration of bound pairs of\ndislocations and that of a locally amorphous state. The relevance of this\nobservation to the issue of the nature of 2D melting is discussed.",
        "positive": "Ramsey fringes in a Bose-Einstein condensate between atoms and molecules: In a recent experiment, a Feshbach scattering resonance was exploited to\nobserve Ramsey fringes in a $^{85}$Rb Bose-Einstein condensate. The oscillation\nfrequency corresponded to the binding energy of the molecular state. We show\nthat the observations are remarkably consistent with predictions of a resonance\nfield theory in which the fringes arise from oscillations between atoms and\nmolecules."
    },
    {
        "anchor": "Rate effects on layering of a confined linear alkane: We perform drainage experiments of a linear alkane fluid (n-hexadecane) down\nto molecular thicknesses, and focus on the role played by the confinement rate.\nWe show that molecular layering is strongly influenced by the velocity at which\nthe confining walls are approached: under high enough shear rates, the confined\nmedium behaves as a structureless liquid of enhanced viscosity for film\nthickness below $\\sim$10 nm. Our results also lead us to conclude that a\nrapidly confined film can be quenched in a metastable disordered state, which\nmight be related with recent intriguing results on the shear properties of\nconfined films produced at different rates [Zhu and Granick, Phys. Rev. Lett.\n{\\bf 93}, 096101 (2004)].",
        "positive": "Phase separation in binary mixtures of active and passive particles: We study binary mixtures of small active and big passive athermal particles\ninteracting via soft repulsive forces on a frictional substrate. Athermal self\npropelled particles are known to phase separate into a dense aggregate and a\ndilute gas-like phase at fairly low packing fractions. Known as {\\emph\n{motility induced phase separation}}, this phenomenon governs the behaviour of\nbinary mixtures for small to intermediate size ratios of the particle species.\nAn effective attraction between passive particles, due to the surrounding\nactive medium, leads to true phase separation for large size ratios and volume\nfractions of active particles. The effective interaction between active and\npassive particles can be attractive or repulsive at short range depending on\nthe size ratio and volume fractions of the particles. This affects the\nclustering of passive particles. We find three distinct phases based on the\nspatial distribution of passive particles.\n  The cluster size distribution of passive particles decays exponentially in\nthe {\\emph{homogeneous phase}}. It decays as a power law with an exponential\ncutoff in the {\\emph{clustered phase}} and tends to a power law as the system\napproaches the transition to the {\\emph{phase separated state}}. We present a\nphase diagram in the plane defined by the size ratio and volume fraction of\npassive particles."
    },
    {
        "anchor": "Confinement dynamics of a semiflexible chain inside nano-spheres: We study the conformations of a semiflexible chain, confined in nano-scaled\nspherical cavities, under two distinct processes of confinement. Radial\ncontraction and packaging are employed as two confining procedures. The former\nmethod is performed by gradually decreasing the diameter of a spherical shell\nwhich envelopes a confined chain. The latter procedure is carried out by\ninjecting the chain inside a spherical shell through a hole on the shell\nsurface. The chain is modeled with a rigid body molecular dynamics simulation\nand its parameters are adjusted to DNA base-pair elasticity. Directional order\nparameter is employed to analyze and compare the confined chain and the\nconformations of the chain for two different sizes of the spheres are studied\nin both procedures. It is shown that for the confined chains in the sphere\nsizes of our study, they appear in spiral or tennis-ball structures, and the\ntennis-ball structure is more likely to be observed in more compact\nconfinements. Our results also show that the dynamical procedure of confinement\nand the rate of the confinement are influential parameters of the structure of\nthe chain inside spherical cavities.",
        "positive": "Athermal quasistatic cavitation in amorphous solids: effect of random\n  pinning: Amorphous solids are known to fail catastrophically via fracture, wherein\ncavitation at nano-metric scales is known to play a significant role.\nMicro-alloying via inclusions is often used as a means to increase the fracture\ntoughness of amorphous solids. Modeling such inclusions as randomly pinned\nparticles that move only affinely and do not participate in plastic relaxation,\nwe study how the pinning influences the process of cavitation-driven fracture\nin an amorphous solid. Using extensive numerical simulations and probing in the\nathermal quasistatic limit, we show that just by pinning a very small fraction\nof particles, the tensile strength is increased and also the cavitation is\ndelayed. Further, the cavitation that is expected to be spatially heterogeneous\nbecomes spatially homogeneous by forming a large number of small cavities\ninstead of a dominant cavity."
    },
    {
        "anchor": "Neutral polyphosphocholine-modified liposomes as boundary\n  superlubricants: Boundary lubrication is associated with two sliding molecularly thin\nlubricated film-coated surfaces, where the energy dissipation occurs at the\nslip-plane between lubricated films. The hydration lubrication paradigm, which\naccounts for ultralow friction in aqueous media, has been extended to various\nsystems, with phosphatidylcholine (PC) lipids recognized as extremely efficient\nlubrication elements due to their high hydration level. In this work, we extend\na previous study (Lin et al., Langmuir 35 (2019) 6048-6054), where a charged\nlipid-poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) conjugate was\nprepared, to the very different case of a neutral lipid-PMPC) conjugate. This\nneutral molecule stabilizes the liposomes by attaching highly water-soluble\nPMPC to the surface of liposomes with its lipid moieties incorporated in the\nlipid bilayers. Such neutral polyphosphocholinated liposomes provide a surface\nlubricity which is well within the superlubrication regime (coefficient of\nfriction = ca. 10-3 or even lower). In contrast, negatively charged\nlipid/polyphosphocholine conjugates modified liposomes were unable to adsorb on\nnegatively-charged (mica) surfaces. Our method provides stable liposomes that\ncan adsorb on negatively charged surfaces and provide superlubricity.",
        "positive": "Effects of hydrodynamic interactions on rectified transport of\n  self-propelled particles: Directed transport of self-propelled particles is numerically investigated in\na three-dimensional asymmetric potential. Beside the steric repulsive forces,\nhydrodynamic interactions between particles have been taken into account in an\napproximate way. From numerical simulations, we find that hydrodynamic\ninteractions can strongly affect the rectified transport of self-propelled\nparticles. Hydrodynamic interactions enhance the performance of the rectified\ntransport when particles can easily pass across the barrier of the potential,\nand reduce the rectified transport when particles are mainly trapped in the\npotential well."
    },
    {
        "anchor": "Dynamic Properties of Motor Proteins with Two Subunits: The dynamics of motor protein molecules that have two subunits is\ninvestigated using simple discrete stochastic models. Exact steady-state\nanalytical expressions are obtained for velocities and dispersions for any\nnumber of intermediate states and conformations between the corresponding\nbinding states of proteins. These models enabled a detailed description and\ncomparison of two possible mechanisms of the motion of motor proteins along the\nlinear tracks: the hand-over-hand mechanism when the motion of subunits\nalternate, and the inchworm mechanism when one subunit is always trailing\nanother one. It is shown that particles in the hand-over-hand mechanism move\nfaster and fluctuate more than the molecules in the inchworm mechanism. The\neffect of external forces on dynamic properties of motor proteins is discussed.\nFinally, a method is proposed for distinguishing between these two mechanisms\nbased on experimental observations.",
        "positive": "Block Analysis for the Calculation of Dynamic and Static Length Scales\n  in Glass-Forming Liquids: We present {\\it block analysis}, an efficient method to perform finite-size\nscaling for obtaining the length scale of dynamic heterogeneity and the\npoint-to-set length scale for generic glass-forming liquids. This method\ninvolves considering blocks of varying sizes embedded in a system of a fixed\n(large) size. The length scale associated with dynamic heterogeneity is\nobtained from a finite-size scaling analysis of the dependence of the\nfour-point dynamic susceptibility on the block size. The block size dependence\nof the variance of the $\\alpha$-relaxation time yields the static point-to-set\nlength scale. The values of the obtained length scales agree quantitatively\nwith those obtained from other conventional methods. This method provides an\nefficient experimental tool for studying the growth of length scales in systems\nsuch as colloidal glasses for which performing finite-size scaling by carrying\nout experiments for varying system sizes may not be feasible."
    },
    {
        "anchor": "Dynamics of polymers: classic results and recent developments: In this chapter we review concepts and theories of polymer dynamics. We think\nof it as an introduction to the topic for scientists specializing in other\nsubfields of statistical mechanics and condensed matter theory, so, for the\nreaders reference, we start with a short review of the equilibrium static\nproperties of polymer systems. Most attention is paid to the dynamics of\nunentangled polymer systems, where apart from classical Rouse and Zimm models\nwe review some recent scaling and analytical generalizations. The dynamics of\nsystems with entanglements is also briefly reviewed. Special attention is paid\nto the discussion of comparatively weakly understood topological states of\npolymer systems and possible approaches to the description of their dynamics.",
        "positive": "Theory of electrolyte solutions in a slit charged pore: effects of\n  structural interactions and specific adsorption of ions: In this paper, we present a continuation of our research on modeling\nelectrolyte solutions within charged slit pores. We make use of the model\ndeveloped by Blossey et al., which takes into account the structural\ninteractions between ions through a bilinear form over the gradients of local\nionic concentrations in the grand thermodynamic potential, as well as their\nsteric interactions through the lattice gas model. The structural interactions\nmay describe effects of the molecular structure of ions at a phenomenological\nlevel. For example, these effects include steric effects due to non-spherical\nshapes of ions, their conformation lability, and solvent effects. In addition,\nwe explore their specific interactions with the pore walls by incorporating\nexternal attractive potentials. Our primary focus is on observing the behavior\nof ionic concentration profiles and the disjoining pressure as the pore width\nchanges. By starting with the local mechanical equilibrium condition, we derive\na general expression for the disjoining pressure. Our findings indicate that\nconsidering the structural interactions of ions leads to a pronounced minimum\non the disjoining pressure profiles at small pore widths. We attribute this\nminimum to the formation of electric double layers on the electrified surfaces\nof the pore. Additionally, our results demonstrate that inclusion of the\nattractive interactions of ions with the pore walls enhances this minimum and\nshifts it to smaller pore thicknesses. Our theoretical discoveries may be\nuseful for those involved in supercapacitor electrochemical engineering,\nparticularly when working with porous electrodes that have been infused with\nconcentrated electrolyte solutions."
    },
    {
        "anchor": "Multiplicity of actuated shapes in woven fabrics with twisted Janus\n  fibres: We investigate actuation of woven fabrics including active Janus fibres with\nan imposed twist, which bend in variable directions upon phase transition\nbetween isotropic and nematic state. The essential feature of textiles\nincorporating a pair of Janus fibres with a mismatched pitch or handedness of\ncoiling is the existence of multiple stable shapes with different energies\nwithin a certain range of the extension coefficient. If the active fibres are\nclosed into a ring, torsion develops to accommodate adjustment of the direction\nof bending. The structure is generally stabilised by adding more passive\nfilaments, and multistability is observed also in this case.",
        "positive": "Observation of vortex phase singularities in Bose-Einstein condensates: We have observed phase singularities due to vortex excitation in\nBose-Einstein condensates. Vortices were created by moving a laser beam through\na condensate. They were observed as dislocations in the interference fringes\nformed by the stirred condensate and a second unperturbed condensate. The\nvelocity dependence for vortex excitation and the time scale for\nre-establishing a uniform phase across the condensate were determined."
    },
    {
        "anchor": "In situ stimulation of self-assembly tunes the elastic properties of\n  interpenetrated glycolipid-biopolymer biobased hydrogels: Hydrogels are widespread soft materials, which can serve a wide range of\napplications. The control over the viscoelastic properties of the gel is of\nparamount importance. Ongoing environmental issues have raised the consumer's\nconcern towards the use of more sustainable materials, including hydrogels.\nHowever, are greener materials compatible with high functionality? In a\nsafe-by-design approach, this work demonstrates that functional hydrogels with\nin situ responsivity of their elastic properties by external stimuli can be\ndeveloped from entirely ``sustainable'' components, a biobased amphiphile and\nbiopolymers (gelatin, chitosan and alginate). The bioamphiphile is a\nstimuli-responsive glycolipid obtained by microbial fermentation, which can\nself-assemble into fibers, but also micelles or vesicles, in water under high\ndilution and by a rapid variation of the stimuli. The elastic properties of the\nbioamphiphile/biopolymer interpenetrated hydrogels can be modulated by\nselectively triggering the phase transition of the glycolipid and/or the\nbiopolymer inside the gel by mean of temperature or pH.",
        "positive": "Shear induced drainage in foamy yield-stress fluids: Shear induced drainage of a foamy yield stress fluid is investigated using\nMRI techniques. Whereas the yield stress of the interstitial fluid stabilizes\nthe system at rest, a fast drainage is observed when a horizontal shear is\nimposed. It is shown that the sheared interstitial material behaves as a\nviscous fluid in the direction of gravity, the effective viscosity of which is\ncontrolled by shear in transient foam films between bubbles. Results provided\nfor several bubble sizes are not captured by the R^2 scaling classically\nobserved for liquid flow in particulate systems, such as foams and thus\nconstitute a remarkable demonstration of the strong coupling of drainage flow\nand shear induced interstitial flow. Furthermore, foam films are found to be\nresponsible for the unexpected arrest of drainage, thus trapping irreversibly a\nsignificant amount of interstitial liquid."
    },
    {
        "anchor": "Recasting a model atomistic glassformer as a system of icosahedra: We consider a binary Lennard-Jones glassformer whose super-Arrhenius dynamics\nare correlated with the formation of icosahedral structures. Upon cooling these\nicosahedra organize into mesoclusters. We recast this glassformer as an\neffective system of icosahedra which we describe with a population dynamics\nmodel. This model we parameterize with data from the temperature regime\naccessible to molecular dynamics simulations. We then use the model to\ndetermine the population of icosahedra in mesoclusters at arbitrary\ntemperature. Using simulation data to incorporate dynamics into the model we\npredict relaxation behavior at temperatures inaccessible to conventional\napproaches. Our model predicts super-Arrhenius dynamics whose relaxation time\nremains finite for non-zero temperature.",
        "positive": "Morphological phase transitions of thin fluid films on chemically\n  structured substrates: Using an interface displacement model derived from a microscopic density\nfunctional theory we investigate thin liquidlike wetting layers adsorbed on\nflat substrates with an embedded chemical heterogeneity forming a stripe. For a\nwide range of effective interface potentials we find first-order phase\ntransitions as well as continuous changes between lateral interfacial\nconfigurations bound to and repelled from the stripe area. We determine phase\ndiagrams and discuss the conditions under which these morphological changes\narise."
    },
    {
        "anchor": "Tagged-particle motion in a dense confined liquid: We investigate the dynamics of a tagged particle embedded in a strongly\ninteracting confined liquid enclosed between two opposing flat walls. Using the\nZwanzig-Mori projection operator formalism we obtain an equation of motion for\nthe incoherent scattering function suitably generalized to account for the lack\nof translational symmetry. We close the equations of motion by a\nself-consistent mode-coupling ansatz. The interaction of the tracer with the\nsurrounding liquid is encoded in generalized direct correlation functions. We\nextract the in-plane dynamics and provide a microscopic expression for the\ndiffusion coefficient parallel to the walls. The solute particle may differ in\nsize or interaction from the surrounding host-liquid constituents offering the\npossibility of a systematic analysis of dynamic effects on the tagged-particle\nmotion in confinement.",
        "positive": "A characteristic lengthscale causes anomalous size effects and boundary\n  programmability in mechanical metamaterials: The architecture of mechanical metamaterialsis designed to harness geometry,\nnon-linearity and topology to obtain advanced functionalities such as shape\nmorphing, programmability and one-way propagation. While a purely geometric\nframework successfully captures the physics of small systems under idealized\nconditions, large systems or heterogeneous driving conditions remain\nessentially unexplored. Here we uncover strong anomalies in the mechanics of a\nbroad class of metamaterials, such as auxetics, shape-changers or topological\ninsulators: a non-monotonic variation of their stiffness with system size, and\nthe ability of textured boundaries to completely alter their properties. These\nstriking features stem from the competition between rotation-based\ndeformations---relevant for small systems---and ordinary elasticity, and are\ncontrolled by a characteristic length scale which is entirely tunable by the\narchitectural details. Our study provides new vistas for designing, controlling\nand programming the mechanics of metamaterials in the thermodynamic limit."
    },
    {
        "anchor": "Interfacial and wetting properties of a binary point Yukawa fluid: We investigate the interfacial phase behavior of a binary fluid mixture\ncomposed of repulsive point Yukawa particles. Using a simple approximation for\nthe Helmholtz free energy functional, which yields the random phase\napproximation (RPA) for the pair direct correlation functions, we calculate the\nequilibrium fluid density profiles of the two species of particles adsorbed at\na planar wall. We show that for a particular choice (repulsive exponential) of\nthe wall potentials and the fluid pair-potential parameters, the Euler-Lagrange\nequations for the equilibrium fluid density profiles may be transformed into a\nsingle ordinary differential equation and the profiles obtained by a simple\nquadrature. For certain other choices of the fluid pair-potential parameters\nfluid-fluid phase separation of the bulk fluid is observed. We find that when\nsuch a mixture is exposed to a planar hard-wall, the fluid exhibits complete\nwetting on the species 2 poor side of the binodal, i.e. we observe a thick film\nof fluid rich in species 2 adsorbed at the hard-wall. The thickness of the\nwetting film grows logarithmically with the concentration difference between\nthe fluid state-point and the binodal and is proportional to the bulk\ncorrelation length of the intruding (wetting) fluid phase. However, for state\npoints on the binodal that are further from the critical point, we find there\nis no thick wetting film. We determine the accompanying line of first-order\n(pre-wetting) surface phase transitions which separate a thin and thick\nadsorbed film. We show that for some other choices of repulsive wall potentials\nthe pre-wetting line is still present, but its location and extent in the phase\ndiagram is strongly dependent on the wall-fluid interaction parameters.",
        "positive": "Programming Boundary Deformation Patterns in Active Networks: Active materials take advantage of their internal sources of energy to\nself-organize in an automated manner. This feature provides a novel opportunity\nto design micron-scale machines with minimal required control. However,\nself-organization goes hand in hand with predetermined dynamics that are hardly\nsusceptible to environmental perturbations. Therefore utilizing this feature of\nactive systems requires harnessing and directing the macroscopic dynamics to\nachieve specific functions; which in turn necessitates understanding the\nunderlying mechanisms of active forces. Here we devise an optical control\nprotocol to engineer the dynamics of active networks composed of microtubules\nand light-activatable motor proteins. The protocol enables carving activated\nnetworks of different shapes, and isolating them from the embedding solution.\nStudying a large set of shapes, we observe that the active networks contract in\na shape-preserving manner that persists over the course of contraction. We\nformulate a coarse-grained theory and demonstrate that self-similarity of\ncontraction is associated with viscous-like active stresses. These findings\nhelp us program the dynamics of the network through manipulating the light\nintensity in space and time, and maneuver the network into bending in specific\ndirections, as well as temporally alternating directions. Our work improves\nunderstanding the active dynamics in contractile networks, and paves a new path\ntowards engineering the dynamics of a large class of active materials."
    },
    {
        "anchor": "Thermodynamic Control of Activity Patterns in Cytoskeletal Networks: We aim to identify the control principles governing the adaptable formation\nof non-equilibrium structures in actomyosin networks. We build a\nphenomenological model and predict that biasing the energy dissipated by\nmolecular motors should effectively renormalize the motor-mediated interactions\nbetween actin filaments. Indeed, using methods from large deviation theory, we\ndemonstrate that biasing energy dissipation is equivalent to modulating the\nmotor rigidity and results in an aster-to-bundle transition. From the\nsimulation statistics, we extract a relation between the biasing parameter and\nthe corresponding normalized motor rigidity. This work elucidates the\nrelationship between energy dissipation, effective interactions, and pattern\nformation in active biopolymer networks, providing a control principle of\ncytoskeletal structure and dynamics.",
        "positive": "Harnessing Synthetic Active Particles for Physical Reservoir Computing: The processing of information is an indispensable property of living systems\nrealized by networks of active processes with enormous complexity. They have\ninspired many variants of modern machine learning one of them being reservoir\ncomputing, in which stimulating a network of nodes with fading memory enables\ncomputations and complex predictions. Reservoirs are implemented on computer\nhardware, but also on unconventional physical substrates such as mechanical\noscillators, spins, or bacteria often summarized as physical reservoir\ncomputing. Here we demonstrate physical reservoir computing with a synthetic\nactive microparticle system that self-organizes from an active and passive\ncomponent into inherently noisy nonlinear dynamical units. The\nself-organization and dynamical response of the unit is the result of a delayed\npropulsion of the microswimmer to a passive target. A reservoir of such units\nwith a self-coupling via the delayed response can perform predictive tasks\ndespite the strong noise resulting from Brownian motion of the microswimmers.\nTo achieve efficient noise suppression, we introduce a special architecture\nthat uses historical reservoir states for output. Our results pave the way for\nthe study of information processing in synthetic self-organized active particle\nsystems."
    },
    {
        "anchor": "Particle-scale statistical theory for hydrodynamically induced polar\n  ordering in microswimmer suspensions: Previous particle-based computer simulations have revealed a significantly\nmore pronounced tendency of spontaneous global polar ordering in puller\n(contractile) microswimmer suspensions than in pusher (extensile) suspensions.\nWe here evaluate a microscopic statistical theory to investigate the emergence\nof such order through a linear instability of the disordered state. For this\npurpose, input concerning the orientation-dependent pair-distribution function\nis needed, and we discuss corresponding approaches, particularly a heuristic\nvariant of the Percus test-particle method applied to active systems. Our\ntheory identifies an inherent evolution of polar order in planar systems of\npuller microswimmers, if mutual alignment due to hydrodynamic interactions\novercomes the thermal dealignment by rotational diffusion. In the theory, the\ncause of orientational ordering can be traced back to the actively induced\nhydrodynamic rotation--translation coupling between the swimmers. Conversely,\ndisordered pusher suspensions remain linearly stable against homogeneous polar\norientational ordering. We expect that our results can be confirmed in\nexperiments on (semi-)dilute active microswimmer suspensions, based, for\ninstance, on biological pusher- and puller-type swimmers.",
        "positive": "Molecular dynamics simulation of orientational glass formation in\n  anisotropic particle systems in three dimensions: We propose a simple microscopic model of molecular dynamics simulation to\nstudy orientational glass in three dimensions. We present simulation results\nfor mixtures of mildly anisotropic particles and spherical impurities. We\nrealize fcc solids without orientational order in a rotator phase. As the\ntemperature $T$ is lowered, the disordered matrix is gradually replaced by four\nkinds of orientationally ordered, rhombohedral domains. Two-phase coexistence\nis realized in a temperature window. The impurities serve to anchor the\norientations of the surrounding anisotropic particles, resulting in finely\ndivided domains or medium long-range orientational order. We examine the\nrotational dynamics of the molecular orientations which is slowed down at low\n$T$. We predict the shape memory effect under a stretching cycle due to\ninter-variant transformation."
    },
    {
        "anchor": "The Helical Superstructure of Intermediate Filaments: Intermediate filaments are the least explored among the large cytoskeletal\nelements. We show here that they display conformational anomalies in narrow\nmicrofluidic channels. Their unusual behavior can be understood as the\nconsequence of a previously undetected, large scale helically curved\nsuperstructure. Confinement in a channel orders the otherwise soft, strongly\nfluctuating helical filaments and enhances their structural correlations,\ngiving rise to experimentally detectable, strongly oscillating tangent\ncorrelation functions. We propose an explanation for the detected intrinsic\ncurving phenomenon - an elastic shape instability that we call autocoiling. The\nmechanism involves self-induced filament buckling via a surface stress located\nat the outside of the cross-section. The results agree with ultrastructural\nfindings and rationalize for the commonly observed looped intermediate filament\nshapes.",
        "positive": "Phase diagram of hard colloidal platelets: a theoretical account: We construct the complete liquid crystal phase diagram of hard plate-like\ncylinders for variable aspect ratio using Onsager's second virial theory with\nthe Parsons-Lee decoupling approximation to account for higher-body\ninteractions in the isotropic and nematic fluid phases. The stability of the\nsolid (columnar) state at high packing fraction is included by invoking a\nsimple equation of state based on a Lennard-Jones-Devonshire (LJD) cell model\nwhich has proven to be quantitatively reliable over a large range of packing\nfractions. By employing an asymptotic analysis based on the Gaussian\napproximation we are able to show that the nematic-columnar transition is\nuniversal and independent of particle shape. The predicted phase diagram is in\nqualitative agreement with simulation results."
    },
    {
        "anchor": "Undulations of smectic A layers in achiral liquid crystals manifested as\n  stripe textures: Self-assembly of organic molecules represents a fascinating playground to\ncreate various liquid crystalline (LC) nanostructures. In this work, we study\nlayer undulations on micrometer scale in smectic A phases for achiral\ncompounds, experimentally demonstrated as regular stripe patterns induced by\nthermal treatment. Undulations including their anharmonic properties are\nevaluated by means of polarimetric imaging and light diffraction experiments in\ncells with various thicknesses. The key role in stripe formation is played by\nhigh negative values of the thermal expansion coefficient.",
        "positive": "Spectral holographic trapping: Creating dynamic force landscapes with\n  polyphonic waves: Acoustic trapping uses forces exerted by sound waves to transport small\nobjects along specified trajectories in three dimensions. The structure of the\nacoustic force landscape is governed by the amplitude and phase profiles of the\nsound's pressure wave. These profiles can be controlled through deliberate\nspatial modulation of monochromatic waves, by analogy to holographic optical\ntrapping. Alternatively, spatial and temporal control can be achieved by\ninterfering a small number of sound waves at multiple frequencies to create\nacoustic holograms based on spectral content. We demonstrate spectral\nholographic trapping by projecting acoustic conveyor beams that move\nmillimeter-scale objects along prescribed paths, and control the complexity of\nparticle trajectories by tuning the strength of weak reflections. Illustrative\nspectral superpositions of static and dynamic force landscapes enable us to\nrealize two variations on the theme of a wave-driven oscillator, a deceptively\nsimple dynamical system with surprisingly complex phenomenology."
    },
    {
        "anchor": "Chain structure of head-on collisions in boundary driven granular gases: We report a peculiar dynamic phenomenon in granular gases, chain structures\nof head-on collisions caused by the boundary heated mechanism form a network in\nan Airbus micro-gravity experiment and horizontal vibrated one in the\nlaboratory, which differ markedly from the grazing-collision-dominant in\nrandomly driven granular fluid. This new order property is an orientation\ncorrelation between the relative position and the relative velocity of any\nparticle pair, which weakens the collision frequency and leads a long range\nboundary effect. By the histogram of the relative position and the relative\nvelocity, we find this position-velocity correlation is not only at limits of\nvery small relative velocities but also large ones, which means the breakdown\nof molecular chaos assumption is not limited to a small portion of the phase\nspace. Through a simple anisotropic angular distribution model of the relative\nposition and the relative velocity, we could modify classical uniform angular\nintegration results of mean field values taking the effect of the observed\ncollision chain structure explicitly into account.",
        "positive": "Effects of confinement on self-assembling systems: Systems in which particles can self-assemble into mono- or bilayers can form\nvariety of stable and metastable structures on a nanometer length scale. For\nthis reason confinement has a particularly strong effect on such systems. We\ndiscuss in some detail effects of confinement on lamellar and cubic phases with\ndouble-diamond structure. Structural deformations in slit geometry are\ndescribed for large and small unit cells of the structure (in units of the\nthickness of the monolayer) and for various strengths of interactions with the\nconfining surfaces. We show how the structural changes of the confined fluid\nare reflected in the measurable solvation force between the confining walls."
    },
    {
        "anchor": "Assembly of nothing: Equilibrium fluids with designed structured\n  porosity: Controlled micro- to meso-scale porosity is a common materials design goal\nwith possible applications ranging from molecular gas adsorption to particle\nsize selective permeability or solubility. Here, we use inverse methods of\nstatistical mechanics to design an isotropic pair interaction that, in the\nabsence of an external field, assembles particles into an inhomogeneous {\\em\nfluid} matrix surrounding pores of prescribed size ordered in a lattice\nmorphology. The pore size can be tuned via modification of temperature or\nparticle concentration. Moreover, modulating density reveals a rich series of\nmicrophase-separated morphologies including pore- or particle-based lattices,\npore- or particle-based columns, and bicontinuous or lamellar structures.\nSensitivity of pore assembly to the form of the designed interaction potential\nis explored.",
        "positive": "Hysteresis and re-entrant melting of a self-organized system of\n  classical particles confined in a parabolic trap: A self-organized system composed of classical particles confined in a\ntwo-dimensional parabolic trap and interacting through a potential with a\nshort-range attractive part and long-range repulsive part is studied as\nfunction of temperature. The influence of the competition between the\nshort-range attractive part of the inter-particle potential and its long-range\nrepulsive part on the melting temperature is studied. Different behaviors of\nthe melting temperature are found depending on the screening length ($\\kappa$)\nand the strength ($B$) of the attractive part of the inter-particle potential.\nA re-entrant behavior and a thermal induced phase transition is observed in a\nsmall region of ($\\kappa,B$)-space. A structural hysteresis effect is observed\nas a function of temperature and physically understood as due to the presence\nof a potential barrier between different configurations of the system."
    },
    {
        "anchor": "Avalanche statistics and time-resolved grain dynamics for a driven heap: We probe the dynamics of intermittent avalanches caused by steady addition of\ngrains to a quasi-two dimensional heap. To characterize the time-dependent\naverage avalanche flow speed v(t), we image the top free surface. To\ncharacterize the grain fluctuation speed dv(t), we use Speckle-Visibility\nSpectroscopy. During an avalanche, we find that the fluctuation speed is\napproximately one-tenth the average flow speed, and that these speeds are\nlargest near the beginning of an event. We also find that the distribution of\nevent durations is peaked, and that event sizes are correlated with the time\ninterval since the end of the previous event. At high rates of grain addition,\nwhere successive avalanches merge into smooth continuous flow, the relationship\nbetween average and fluctuation speeds changes to dv Sqrt[v].",
        "positive": "Geometric frustration in small colloidal clusters: We study the structure of clusters in a model colloidal system with competing\ninteractions using Brownian dynamics simulations. A short-ranged attraction\ndrives clustering, while a weak, long-ranged repulsion is used to model\nelectrostatic charging in experimental systems. The former is treated with a\nshort-ranged Morse attractive interaction, the latter with a repulsive Yukawa\ninteraction. We consider the yield of clusters of specific structure as a\nfunction of the strength of the interactions, for clusters with m=3,4,5,6,7,10\nand 13 colloids. At sufficient strengths of the attractive interaction (around\n10 kT), the average bond lifetime approaches the simulation timescale and the\nsystem becomes nonergodic. For small clusters m<=5 where geometric frustration\nis not relevant, despite nonergodicity, for sufficient strengths of the\nattractive interaction the yield of clusters which maximise the number of bonds\napproaches 100%. However for $m=7$ and higher, in the nonergodic regime we find\na lower yield of these structures where we argue geometric frustration plays a\nsignificant role. $m=6$ is a special case, where two structures, of octahedral\nand C2v symmetry compete, with the latter being favoured by entropic\ncontributions in the ergodic regime and by kinetic trapping in the nonergodic\nregime. We believe that our results should be valid as far as the one-component\ndescription of the interaction potential is valid. A system with competing\nelectrostatic repulsions and van der Waals attractions may be such an example.\nHowever, in some cases, the one-component description of the interaction\npotential may not be appropriate."
    },
    {
        "anchor": "Properties of a nonlinear bath: Experiments, theory, and a stochastic\n  Prandtl-Tomlinson model: A colloidal particle is a prominent example of a stochastic system, and, if\nsuspended in a simple viscous liquid, very closely resembles the case of an\nideal random walker. A variety of new phenomena have been observed when such\ncolloid is suspended in a viscoelastic fluid instead, for example pronounced\nnonlinear responses when the viscoelastic bath is driven out of equilibrium.\nHere, using a micron-sized particle in a micellar solution, we investigate in\ndetail, how these nonlinear bath properties leave their fingerprints already in\nequilibrium measurements, for the cases where the particle is unconfined or\ntrapped in a harmonic potential. We find that the coefficients in an effective\nlinear (generalized) Langevin equation show intriguing inter-dependencies,\nwhich can be shown to arise only in nonlinear baths: For example, the friction\nmemory can depend on the external potential that acts only on the colloidal\nparticle (as recently noted in simulations of molecular tracers in water in\nPhys. Rev. X 7, 041065 (2017)), it can depend on the mass of the colloid, or,\nin an overdamped setting, on its bare diffusivity. These inter-dependencies,\ncaused by so-called fluctuation renormalizations, are seen in an exact small\ntime expansion of the friction memory based on microscopic starting points.\nUsing linear response theory, they can be interpreted in terms of\nmicrorheological modes of force-controlled or velocity-controlled driving. The\nmentioned nonlinear markers are observed in our experiments, which are\nastonishingly well reproduced by a stochastic Prandtl-Tomlinson model mimicking\nthe nonlinear viscoelastic bath. The pronounced nonlinearities seen in our\nexperiments together with the good understanding in a simple theoretical model\nmake this system a promising candidate for exploration of colloidal motion in\nnonlinear stochastic environments.",
        "positive": "An Ising model for the thermal and dynamic properties of supercooled\n  liquids and the glass transition: We describe the behavior of an Ising model with orthogonal dynamics, where\nchanges in energy and changes in alignment never occur during the same Monte\nCarlo (MC) step. This orthogonal Ising model (OIM) allows conservation of\nenergy and conservation of momentum to proceed independently, on their own\npreferred time scales. MC simulations of the OIM mimic more than twenty\ndistinctive characteristics that are commonly found above and below the glass\ntemperature, Tg. Examples include a specific heat that has hysteresis around\nTg, out-of-phase loss that exhibits primary and secondary peaks,\nsuper-Arrhenius T dependence for the alpha response time, and fragilities that\nincrease with increasing system size (N). Mean-field theory for energy\nfluctuations in the OIM yields a novel expression for the super-Arrhenius\ndivergence. Because this divergence is reminiscent of the Vogel-Fulcher-Tammann\n(VFT) law squared, we call it the VFT2 law. A modified Stickel plot, which\nlinearizes the VFT2 law, gives qualitatively consistent agreement with\nmeasurements of primary response (from the literature) on five glass-forming\nliquids. Such agreement with the OIM suggests that several basic features\ngovern supercooled liquids. The freezing of a liquid into a glass involves an\nunderlying 2nd-order transition that is broadened by finite-size effects. The\nVFT2 law comes from energy fluctuations that enhance the pathways through an\nentropy bottleneck, not activation over an energy barrier. Primary response\ntimes vary exponentially with inverse N, consistent with the distribution of\nrelaxation times deduced from measurements. System sizes found via the T\ndependence of the primary response are similar to sizes of independently\nrelaxing regions measured by nuclear magnetic resonance for simple-molecule\nglass-forming liquids. The OIM provides a broad foundation for more-detailed\nmodels of liquid-glass behavior."
    },
    {
        "anchor": "Viscoelastic shear stress relaxation in two-dimensional glass forming\n  liquids: Translational dynamics of two-dimensional glass forming fluids is strongly\ninfluenced by soft, long-wavelength fluctuations first recognized by D. Mermin\nand H. Wagner. As a result of these fluctuations, characteristic features of\nglassy dynamics, such as plateaus in the mean squared displacement and the\nself-intermediate scattering function, are absent in two dimensions. In\ncontrast, Mermin-Wagner fluctuations do not influence orientational relaxation\nand well developed plateaus are observed in orientational correlation\nfunctions. It has been suggested that by monitoring translational motion of\nparticles relative to that of their neighbors, one can recover characteristic\nfeatures of glassy dynamics and thus disentangle the Mermin-Wagner fluctuations\nfrom the two-dimensional glass transition. Here we use molecular dynamics\nsimulations to study viscoelastic relaxation in two and three dimensions. We\nfind different behavior of the dynamic modulus below the onset of slow dynamics\n(determined by the orientational or cage-relative correlation functions) in two\nand three dimensions. The dynamic modulus for two-dimensional supercooled\nfluids is more stretched than for three-dimensional supercooled fluids and it\ndoes not exhibit a plateau, which implies the absence of glassy viscoelastic\nrelaxation. At lower temperatures, the two-dimensional dynamic modulus starts\nexhibiting an intermediate time plateau and decays similarly to the\nthree-dimensional dynamic modulus. The differences in the glassy behavior of\ntwo- and three-dimensional glass forming fluids parallel differences in the\nordering scenarios in two and three dimensions.",
        "positive": "Diffusion at the liquid-vapor interface: Recently, the intrinsic sampling method has been developed in order to\nobtain, from molecular simulations, the intrinsic structure of the liquid-vapor\ninterface that is presupposed in the classical capillary wave theory. Our\npurpose here is to study dynamical processes at the liquid-vapor interface,\nsince this method allows tracking down and analyzing the movement of surface\nmolecules, thus providing, with great accuracy, dynamical information on\nmolecules that are \"at\" the interface. We present results for the coefficients\nfor diffusion parallel and perpendicular to the liquid-vapor interface of the\nLennard-Jones fluid, as well as other time and length parameters that\ncharacterize the diffusion process in this system. We also obtain statistics of\npermanence and residence time. The generality of our results is tested by\nvarying the system size and the temperature; for the later case, an existing\nmodel for alkali metals is also considered. Our main conclusion is that, even\nif diffusion coefficients can still be computed, the turnover processes, by\nwhich molecules enter and leave the intrinsic surface, are as important as\ndiffusion. For example, the typical time required for a molecule to traverse a\nmolecular diameter is very similar to its residence time at the surface."
    },
    {
        "anchor": "Heat transfer between elastic solids with randomly rough surfaces: We study the heat transfer between elastic solids with randomly rough\nsurfaces. We include both the heat transfer from the area of real contact, and\nthe heat transfer between the surfaces in the noncontact regions. We apply a\nrecently developed contact mechanics theory, which accounts for the\nhierarchical nature of the contact between solids with roughness on many\ndifferent length scales. For elastic contact, at the highest (atomic)\nresolution the area of real contact typically consists of atomic (nanometer)\nsized regions, and we discuss the implications of this for the heat transfer.\nFor solids with very smooth surfaces, as is typical in many modern engineering\napplications, the interfacial separation in the non-contact regions will be\nvery small, and for this case we show the importance of the radiative heat\ntransfer associated with the evanescent electromagnetic waves which exist\noutside of all bodies.",
        "positive": "Compact expansion of a repulsive suspension: Short-range repulsion governs the dynamic behavior of matter across length\nscales, from atoms to animals. As the density increases, the dynamics\ntransition from nearest-neighbor to many-body interactions, posing a challenge\nfor an analytical description. Here we use theory, simulations, and experiments\nto show that a suspension of particles with short-range repulsion spreads\ncompactly. Unlike the diffusive boundary of a spreading drop of Brownian\nparticles, a compact expansion is characterized by a density profile that is\nstrictly zero beyond a cutoff distance. Starting from the microscopic\ninteractions, we derive an effective, non-linear diffusion equation and find\nthat the dynamics exhibit two distinct transitions: (1) when very dense,\nparticle-particle interactions extend beyond nearest neighbors, and the\nensemble grows in a self-similar fashion as time to the power of 1/4. (2) at\nlower densities, nearest-neighbor interactions dominate, and the expansion\nslows to logarithmic growth. We examine the second regime experimentally by\nmonitoring the expansion of a dense suspension of charge-stabilized colloids.\nUsing simulations of thousands of particles, we observe the continuous\ncrossover between the self-similar and the logarithmic dynamics. Our results\nare general and robust, with practical implications in engineering and\npharmaceutical industries, where suspensions must operate at extreme densities."
    },
    {
        "anchor": "Slowing down of ring polymer diffusion caused by inter-ring threading: Diffusion of long ring polymers in a melt is much slower than the\nreorganization of their internal structures. While direct evidences for\nentanglements have not been observed in the long ring polymers unlike linear\npolymer melts, threading between the rings is suspected to be the main reason\nfor slowing down of ring polymer diffusion. It is, however, difficult to define\nthe threading configuration between two rings because the rings have no chain\nend. In this work, evidences for threading dynamics of ring polymers are\npresented by using molecular dynamics simulation and applying a novel analysis\nmethod. The simulation results are analyzed in terms of the statistics of\npersistence and exchange times that have proved useful in studying\nheterogeneous dynamics of glassy systems. We find that the threading time of\nring polymer melts increases more rapidly with the degree of polymerization\nthan that of linear polymer melts. This indicates that threaded ring polymers\ncannot diffuse until unthreading event occurs, which results in the slowing\ndown of ring polymer diffusion.",
        "positive": "Fast, accurate, and system-specific variable-resolution modelling of\n  proteins: In recent years, a few multiple-resolution modelling strategies have been\nproposed, in which functionally relevant parts of a biomolecule are described\nwith atomistic resolution, while the remainder of the system is concurrently\ntreated using a coarse-grained model. In most cases, the parametrisation of the\nlatter requires lengthy reference all-atom simulations and/or the usage of\noff-shelf coarse-grained force fields, whose interactions have to be refined to\nfit the specific system under examination. Here, we overcome these limitations\nthrough a novel multi-resolution modelling scheme for proteins, dubbed\ncoarse-grained anisotropic network model for variable resolution simulations,\nor CANVAS. This scheme enables the user-defined modulation of the resolution\nlevel throughout the system structure; a fast parametrisation of the potential\nwithout the necessity of reference simulations; and the straightforward usage\nof the model on the most commonly used molecular dynamics platforms. The method\nis presented and validated on two case studies, the enzyme adenylate kinase and\nthe therapeutic antibody pembrolizumab, by comparing results obtained with the\nCANVAS model against fully atomistic simulations. The modelling software,\nimplemented in python, is made freely available for the community on a\ncollaborative github repository."
    },
    {
        "anchor": "Ultrasonic Study of Water Adsorbed in Nanoporous Glasses: Thermodynamic properties of fluids confined in nanopores differ from those\nobserved in the bulk. To investigate the effect of nanoconfinement on water\ncompressibility, we performed water sorption experiments on two nanoporous\nglass samples while concomitantly measuring the speed of longitudinal and shear\nultrasonic waves in these samples. These measurements yield the longitudinal\nand shear moduli of the water laden nanoporous glass as a function of relative\nhumidity that we utilized in the Gassmann theory to infer the bulk modulus of\nthe confined water. This analysis shows that the bulk modulus (inverse of\ncompressibility) of confined water is noticeably higher than that of the bulk\nwater at the same temperature. Moreover, the modulus exhibits a linear\ndependence on the Laplace pressure. The results for water, which is a polar\nfluid, agree with previous experimental and numerical data reported for\nnon-polar fluids. This similarity suggests that irrespective of intermolecular\nforces, confined fluids are stiffer than bulk fluids. Accounting for fluid\nstiffening in nanopores may be important for accurate interpretation of wave\npropagation measurements in fluid-filled nanoporous media, including in\npetrophysics, catalysis, and other applications, such as in porous materials\ncharacterization.",
        "positive": "Shear banding in large amplitude oscillatory shear (LAOStrain and\n  LAOStress) of polymers and wormlike micelles: We investigate theoretically shear banding in large amplitude oscillatory\nshear (LAOS) of polymers and wormlike micelles. In LAOStrain we find banding at\nlow frequencies and sufficiently high strain rate amplitudes in fluids for\nwhich the underlying constitutive curve of shear stress as a function of shear\nrate is non-monotonic. This is the direct analogue of quasi steady state\nbanding seen in slow strain rate sweeps along the flow curve. At higher\nfrequencies and sufficiently high strain amplitudes we report a different but\nrelated phenomenon, which we call `elastic' shear banding. This is associated\nwith an overshoot in the elastic (Lissajous-Bowditch) curve of stress as a\nfunction of strain. We suggest that this may arise widely even in fluids that\nhave a monotonic underlying constitutive curve, and so do not show steady state\nbanding under a steadily applied shear flow. In LAOStress we report banding in\nfluids that shear thin strongly enough to have either a negatively, or weakly\npositively, sloping region in the underlying constitutive curve, noting again\nthat fluids in the latter category do not display steady state banding in a\nsteadily applied flow. This banding is triggered in each half cycle as the\nstress magnitude transits the region of weak slope in an upward direction, such\nthat the fluid effectively yields. Our numerics are performed in the Rolie-poly\nmodel of polymeric fluids, but we also provide arguments suggesting that our\nresults should apply more widely. Besides banding in the shear rate profile,\nwhich can be measured by velocimetry, we also predict banding in the shear and\nnormal stress components, measurable by birefringence. As a backdrop to\nunderstanding the new results on shear banding in LAOS, we also briefly review\nearlier work on banding in other time-dependent protocols, focusing in\nparticular on shear startup and step stress."
    },
    {
        "anchor": "Collective oscillations in optical matter: Atom and nanoparticle arrays trapped in optical lattices are shown to be\ncapable of sustaining collective oscillations of frequency proportional to the\nstrength of the external light field. The spectrum of these oscillations\ndetermines the mechanical stability of the arrays. This phenomenon is studied\nfor dimers, strings, and two-dimensional planar arrays. Laterally confined\nparticles free to move along an optical channel are also considered as an\nexample of collective motion in partially-confined systems. The fundamental\nconcepts of dynamical response in optical matter introduced here constitute the\nbasis for potential applications to quantum information technology and signal\nprocessing. Experimental realizations of these systems are proposed.",
        "positive": "Svortices and the fundamental modes of the \"snake instability\":\n  Possibility of observation in the gaseous Bose-Einstein Condensate: The connection between quantized vortices and dark solitons in a long and\nthin, waveguide-like trap geometry is explored in the framework of the\nnon-linear Schr\\\"odinger equation. Variation of the transverse confinement\nleads from the quasi-1D regime where solitons are stable to 2D (or 3D)\nconfinement where soliton stripes are subject to a transverse modulational\ninstability known as the ``snake instability''. We present numerical evidence\nof a regime of intermediate confinement where solitons decay into single,\ndeformed vortices with solitonic properties, also called svortices, rather than\nvortex pairs as associated with the ``snake'' metaphor. Further relaxing the\ntransverse confinement leads to production of 2 and then 3 vortices, which\ncorrelates perfectly with a Bogoliubov-de Gennes stability analysis. The decay\nof a stationary dark soliton (or, planar node) into a single svortex is\npredicted to be experimentally observable in a 3D harmonically confined dilute\ngas Bose-Einstein condensate."
    },
    {
        "anchor": "Self-assembly of binary nanoparticle dispersions: from square arrays and\n  stripe phases to colloidal corrals: The generation of nanoscale square and stripe patterns is of major\ntechnological importance since they are compatible with industry-standard\nelectronic circuitry. Recently, a blend of diblock copolymer interacting via\nhydrogen-bonding was shown to self-assemble in square arrays. Motivated by\nthose experiments we study, using Monte Carlo simulations, the pattern\nformation in a two-dimensional binary mixture of colloidal particles\ninteracting via isotropic core-corona potentials. We find a rich variety of\npatterns that can be grouped mainly in aggregates that self-assemble in regular\nsquare lattices or in alternate strips. Other morphologies observed include\ncolloidal corrals that are potentially useful as surface templating agents.\nThis work shows the unexpected versatility of this simple model to produce a\nvariety of patterns with high technological potential.",
        "positive": "Timescale divergence at the shear jamming transition: We find that in simulations of quasi-statically sheared frictional disks, the\nshear jamming transition can be characterized by an abrupt jump in the number\nof force bearing contacts between particles. This mechanical coordination\nnumber increases discontinuously from $Z = 0$ to $Z \\gtrsim d +1$ at a critical\nshear value $\\gamma_c$, as opposed to a smooth increase in the number of\ngeometric contacts. This is accompanied by a diverging timescale $\\tau^*$ that\ncharacterizes the time required by the system to attain force balance when\nsubjected to a perturbation. As the global shear $\\gamma$ approaches the\ncritical value $\\gamma_c$ from below, one observes the divergence of the time\ntaken to relax to a state where all the inter-particle contacts have uniformly\nzero force. Above $\\gamma_{c}$, the system settles into a state characterized\nby finite forces between particles, with the timescale also increasing as\n$\\gamma \\to \\gamma_{c}^{+}$. By using two different protocols to generate force\nbalanced configurations, we show that this timescale divergence is a robust\nfeature that accompanies the shear jamming transition."
    },
    {
        "anchor": "Computer simulations of domain growth in off-critical quenches of\n  two-dimensional binary mixtures: The phase separation of two-dimensional binary mixtures has been studied\nthrough numerical Langevin simulations based on a Ginzburg-Landau free energy.\nWe have considered not symmetric mixtures with and without imposed shear flow.\nIn the sheared case our main results are as follows: (1) domains are distorted\nby the flow; (2) the structure factor has four peaks; (3) excess viscosity\nshows a peak whose position is independent of shear rate but its height\ndecreases increasing shear rate.",
        "positive": "Main phase transition in lipid bilayers: phase coexistence and line\n  tension in a soft, solvent-free, coarse-grained model: We devise a soft, solvent-free, coarse-grained model for lipid bilayer\nmembranes. The non-bonded interactions take the form of a weighted-density\nfunctional which allows us to describe the thermodynamics of self-assembly and\npacking effects of the coarse-grained beads in terms of a density expansion of\nthe equation of state and the weighting functions that regularize the\nmicroscopic bead densities, respectively. Identifying the length and energy\nscales via the bilayer thickness and the thermal energy scale, kT, the model\nqualitatively reproduces key characteristics (e.g., bending rigidity, area per\nlipid molecules, and compressibility) of lipid membranes. We employ this model\nto study the main phase transition between the liquid and the gel phase of the\nbilayer membrane. We accurately locate the phase coexistence using free energy\ncalculations and also obtain estimates for the bare and the thermodynamic line\ntension."
    },
    {
        "anchor": "Chemical analysis and aqueous solution properties of Charged Amphiphilic\n  Block Copolymers PBA-b-PAA synthesized by MADIX: We have linked the structural and dynamic properties in aqueous solution of\namphiphilic charged diblock copolymers poly(butyl acrylate)-b-poly(acrylic\nacid), PBA-b-PAA, synthesized by controlled radical polymerization, with the\nphysico-chemical characteristics of the samples. Despite product imperfections,\nthe samples self-assemble in melt and aqueous solutions as predicted by\nmonodisperse microphase separation theory. However, the PBA core are abnormally\nlarge; the swelling of PBA cores is not due to AA (the Flory parameter\nchiPBA/PAA, determined at 0.25, means strong segregation), but to h-PBA\nhomopolymers (content determined by Liquid Chromatography at the Point of\nExclusion and Adsorption Transition LC-PEAT). Beside the dominant population of\nmicelles detected by scattering experiments, capillary electrophoresis CE\nanalysis permitted detection of two other populations, one of h-PAA, and the\nother of free PBA-b-PAA chains, that have very short PBA blocks and never\nself-assemble. Despite the presence of these free unimers, the self-assembly in\nsolution was found out of equilibrium: the aggregation state is history\ndependant and no unimer exchange between micelles occurs over months\n(time-evolution SANS). The high PBA/water interfacial tension, measured at 20\nmN/m, prohibits unimer exchange between micelles. PBA-b-PAA solution systems\nare neither at thermal equilibrium nor completely frozen systems: internal\nfractionation of individual aggregates can occur.",
        "positive": "Kinetic stability and energetics of simulated glasses created by\n  constant pressure cooling: We use computer simulations to study the cooling rate dependence of the\nstability and energetics of model glasses created at constant pressure\nconditions and compare the results with glasses formed at constant volume\nconditions. To examine the stability, we determine the time it takes for a\nglass cooled and reheated at constant pressure to transform back into a liquid,\n$t_{\\mathrm{trans}}$, and calculate the stability ratio $S =\nt_{\\mathrm{trans}}/\\tau_\\alpha$, where $\\tau_\\alpha$ is the equilibrium\nrelaxation time of the liquid. We find that, for slow enough cooling rates,\ncooling and reheating at constant pressure results in a larger stability ratio\n$S$ than for cooling and reheating at constant volume. We also compare the\nenergetics of glasses obtained by cooling while maintaining constant pressure\nwith those of glasses created by cooling from the same state point while\nmaintaining constant volume. We find that cooling at constant pressure results\nin glasses with lower average potential energy and average inherent structure\nenergy. We note that in model simulations of the vapor deposition process\nglasses are created under constant pressure conditions, and thus they should be\ncompared to glasses obtained by constant pressure cooling."
    },
    {
        "anchor": "Active-Passive Brownian Particle in Two Dimensions: This paper presents a model for active particles in two dimensions with\ntime-dependent self-propulsion speed undergoing both translational and\nrotational diffusion. Usually, for modeling the motion of active particles, the\nself-propulsion speed is assumed to be constant as in the famous model of\nactive Brownian motion. This assumption is far from what may happen in reality.\nHere, we generalize active Brownian motion by considering stochastic\nself-propulsion speed $v(t)$. In particular, we assume that $v(t)$ is a\ntwo-state process with $v=0$ (passive state) and $v=s$ (active state). The\ntransition between the two states is also modeled using the random telegraph\nprocess. It is expected that the presented two-state model where we call it\nactive-passive Brownian particle has the characteristics of both pure active-\nand pure passive-Brownian particle. The analytical results for the first two\nmoments of displacement and the effective diffusion coefficient confirm this\nexpectation. We also show that a run-and-tumble particle (such as a motile\nbacterium) can be mapped to our model so that their diffusivities at large\nscales are equal.",
        "positive": "Curvature-induced clustering of cell adhesion proteins: Cell adhesion proteins typically form stable clusters that anchor the cell\nmembrane to its environment. Several works have suggested that cell membrane\nprotein clusters can emerge from a local feedback between the membrane\ncurvature and the density of proteins. Here, we investigate the effect of such\ncurvature-sensing mechanism in the context of cell adhesion proteins. We show\nhow clustering emerges in an intermediate range of adhesion and\ncurvature-sensing strengths. We identify key differences with the tilt-induced\ngradient sensing mechanism we previously proposed (Lin et al.,\narXiv:2307.03670, 2023)."
    },
    {
        "anchor": "A new non linear mechanism able to generate avalanches based on soil\n  mechanics: We propose a general mechanism based on soil mechanics concepts, such as\ndilatancy and friction, to explain the fact that avalanches stop at an angle\nsmaller than they start: the mechanism involved is linked to the fact that the\nstress field near the free surface of a pile built with inclined strata obeys\nalways the plasticity criteria, even when the slope is smaller than the\nfriction angle. It results from this that the larger the slope angle the\nsmaller the mean stress and the smaller the maximum principal stress. So when\nthe pile rotates to generate the next instability the granular material is\nsubmitted to a decrease of the mean stress, resulting in an increase of its\nyielding angle, which becomes larger than the friction angle. The slope starts\nthen flowing at an angle larger than the friction angle.",
        "positive": "Point Defects in Hard Sphere Crystals: We report numerical calculations of the concentration of interstitials in\nhard-sphere crystals. We find that, in a three-dimensional fcc hard-sphere\ncrystal at the melting point, the concentration of interstitials is 2 * 10^-8.\nThis is some three orders of magnitude lower than the concentration of\nvacancies. A simple, analytical estimate yields a value that is in fair\nagreement with the numerical results."
    },
    {
        "anchor": "Effective wave-equations for the dynamics of cigar-shaped and\n  disc-shaped Bose condensates: Starting from the 3D Gross-Pitaevskii equation and using a variational\napproach, we derive an effective 1D wave-equation that describes the axial\ndynamics of a Bose condensate confined in an external potential with\ncylindrical symmetry. The trapping potential is harmonic in the transverse\ndirection and generic in the axial one. Our equation, that is a time-dependent\nnon-polynomial nonlinear Schr\\\"odinger equation (1D NPSE), can be used to model\ncigar-shaped condensates, whose dynamics is essentially 1D. We show that 1D\nNPSE gives much more accurate results than all other effective equations\nrecently proposed. By using 1D NPSE we find analytical solutions for bright and\ndark solitons, which generalize the ones known in the literature. We deduce\nalso an effective 2D non-polynomial Schr\\\"odinger equation (2D NPSE) that\nmodels disc-shaped Bose condensates confined in an external trap that is\nharmonic along the axial direction and generic in the transverse direction. In\nthe limiting cases of weak and strong interaction, our approach gives rise to\nSchr\\\"odinger-like equations with different polynomial nonlinearities.",
        "positive": "Understanding Mechanochemical Coupling in Kinesins Using First-Passage\n  Time Processes: Kinesins are processive motor proteins that move along microtubules in a\nstepwise manner, and their motion is powered by the hydrolysis of ATP. Recent\nexperiments have investigated the coupling between the individual steps of\nsingle kinesin molecules and ATP hydrolysis, taking explicitly into account\nforward steps, backward steps and detachments. A theoretical study of\nmechanochemical coupling in kinesins, which extends the approach used\nsuccessfully to describe the dynamics of conventional motor proteins, is\npresented. The possibility of irreversible detachments of kinesins from the\nmicrotubules is also explicitly taken into account. Using the method of first-\npassage times, experimental data on the mechanochemical coupling in kinesins\nare fully described using the simplest two-state model. It is shown that the\ndwell times for the kinesin to move one step forward or backward, or to\ndissociate irreversibly are the same, although the probabilities of these\nevents are different. It is concluded that the current theoretical view, that\nonly the forward motion of the motor protein molecule is coupled to ATP\nhydrolysis, is consistent with all available experimental observations for\nkinesins."
    },
    {
        "anchor": "Asymmetric periodic boundary conditions for molecular dynamics and\n  coarse-grained simulations of nucleic acids: Periodic boundary conditions are commonly applied in molecular dynamics\nsimulations in the microcanonical (NVE), canonical (NVT) and\nisothermal-isobaric (NpT) ensembles. In their simplest application, a\nbiological system of interest is placed in the middle of a solvation box, which\nis chosen 'sufficiently large' to minimize any numerical artefacts associated\nwith the periodic boundary conditions. This practical approach brings\nlimitations to the size of biological systems that can be simulated. Here, we\nstudy simulations of effectively infinitely-long nucleic acids, which are\nsolvated in the directions perpendicular to the polymer chain, while periodic\nboundary conditions are also applied along the polymer chain. We study the\neffects of these asymmetric periodic boundary conditions (APBC) on the\nsimulated results, including the mechanical properties of biopolymers and the\nproperties of the surrounding solvent. To get some further insights into the\nadvantages of using the APBC, a coarse-grained worm-like chain model is first\nstudied, illustrating how the persistence length can be extracted from local\nproperties of the polymer chain, which are less affected by the APBC than some\nglobal averages. This is followed by all-atom molecular dynamics simulations of\nDNA in ionic solutions, where we use the APBC to investigate sequence-dependent\nproperties of DNA molecules and properties of the surrounding solvent.",
        "positive": "Shear banding in soft glassy materials: Many soft materials, including foams, dense emulsions, micro gel bead\nsuspensions, star polymers, dense packing of surfactant onion micelles, and\ntextured morphologies of liquid crystals, share the basic \"glassy\" features of\nstructural disorder and metastability. These in turn give rise to several\nnotable features in the low frequency shear rheology (deformation and flow\nproperties) of these materials: in particular, the existence of a yield stress\nbelow which the material behaves like a solid, and above which it flows like a\nliquid. In the last decade, intense experimental activity has also revealed\nthat these materials often display a phenomenon known as shear banding, in\nwhich the flow profile across the shear cell exhibits macroscopic bands of\ndifferent viscosity. Two distinct classes of yield stress fluid have been\nidentified: those in which the shear bands apparently persist permanently (for\nas long as the flow remains applied), and those in which banding arises only\ntransiently during a process in which a steady flowing state is established out\nof an initial rest state (for example, in a shear startup or step stress\nexperiment). After surveying the motivating experimental data, we describe\nrecent progress in addressing it theoretically, using the soft glassy rheology\nmodel and a simple fluidity model. We also briefly place these theoretical\napproaches in the context of others in the literature, including elasto-plastic\nmodels, shear transformation zone theories, and molecular dynamics simulations.\nWe discuss finally some challenges that remain open to theory and experiment\nalike."
    },
    {
        "anchor": "Tunable transport in bi-disperse porous materials with vascular\n  structure: We study transport in synthetic, bi-disperse porous structures, with arrays\nof microchannels interconnected by a nanoporous layer. These structures are\ninspired by the xylem tissue in vascular plants, in which sap water travels\nfrom the roots to the leaves to maintain hydration and carry micronutrients. We\nexperimentally evaluate transport in three conditions: high pressure-driven\nflow, spontaneous imbibition, and transpiration-driven flow. The latter case\nresembles the situation in a living plant, where bulk liquid water is\ntransported upwards in a metastable state (negative pressure), driven by\nevaporation in the leaves; here we report stable, transpiration-driven flows\ndown to $\\sim -15$ MPa of driving force. By varying the shape of the\nmicrochannels, we show that we can tune the rate of these transport processes\nin a predictable manner, using a simple analytical (effective medium) approach\nand numerical simulations of the flow field in the bi-disperse media. We also\nshow that the spontaneous imbibition behavior of a single structure - with\nfixed geometry - can behave very differently depending on its preparation\n(filled with air, vs. evacuated), because of a dramatic change in the\nconductance of vapor in the microchannels; this change offers a second way to\ntune the rate of transport in bi-disperse, xylem-like structures, by switching\nbetween air-filled and evacuated states.",
        "positive": "Critical Casimir interaction of ellipsoidal colloids with a planar wall: Based on renormalization group concepts and explicit mean field calculations\nwe study the universal contribution to the effective force and torque acting on\nan ellipsoidal colloidal particle which is dissolved in a critical fluid and is\nclose to a homogeneous planar substrate. At the same closest distance between\nthe substrate and the surface of the particle, the ellipsoidal particle prefers\nan orientation parallel to the substrate and the magnitude of the fluctuation\ninduced force is larger than if the orientation of the particle is\nperpendicular to the substrate. The sign of the critical torque acting on the\nellipsoidal particle depends on the type of boundary conditions for the order\nparameter at the particle and substrate surfaces, and on the pivot with respect\nto which the particle rotates."
    },
    {
        "anchor": "Effects of hydrogen bonding on supercooled liquid dynamics and the\n  implications for supercooled water: The supercooled state of bulk water is largely hidden by unavoidable\ncrystallization, which creates an experimentally inaccessible temperature\nregime - a 'no man's land'. We address this and circumvent the crystallization\nproblem by systematically studying the supercooled dynamics of hydrogen bonded\noligomeric liquids (glycols), where water corresponds to the chain-ends alone.\nThis novel approach permits a 'dilution of water' by altering the hydrogen bond\nconcentration via variations in chain length. We observe a dynamic crossover in\nthe temperature dependence of the structural relaxation time for all glycols,\nconsistent with the common behavior of most supercooled liquids. We find that\nthe crossover becomes more pronounced for increasing hydrogen bond\nconcentrations, which leads to the prediction of a marked dynamic transition\nfor water within 'no man's land' at T~220 K. Interestingly, the predicted\ntransition thus takes place at a temperature where a so called 'strong-fragile'\ntransition has previously been suggested. Our results, however, imply that the\ndynamic transition of supercooled water is analogous to that commonly observed\nin supercooled liquids. Moreover, we find support also for the existence of a\nsecondary relaxation of water with behavior analogous to that of the secondary\nrelaxation observed for the glycols.",
        "positive": "Surface directed spinodal decomposition of fluids confined in\n  cylindrical pore: The surface directed spinodal decomposition of a binary liquid confined\ninside cylindrical pore is investigated using molecular dynamics simulation.\nOne component of the liquid wets the pore surface while the other remains\nneutral. A variety of wetting conditions are studied. For the partial wetting\ncase, after an initial period of phase separation, the domains organize\nthemselves into plug-like structure and the system enters into a metastable\nstate. Therefore, a complete phase separation is never achieved. Analysis of\ndomain growth and the structure factor suggests an one-dimensional growth\ndynamics for partial wetting case. As the wetting interaction is increased\nbeyond a critical value, a transition from the plug-like to tube-like domain\nformation is observed which corresponds to the full wetting morphology. Thus, a\ncomplete phase separation is achieved as the wetting species moves towards the\npore surface and forms layers enclosing the non wetting species residing around\nthe axis of the cylinder. The coarsening dynamics of both the species are\nstudied separately. The wetting species is found to follow a two-dimensional\ndomain growth dynamics with a growth exponent 1/2 in the viscous hydrodynamic\nregime. This was substantiated by the Porod tail of the structure factor. On\nthe other hand, the domain grows linearly with time for the non wetting\nspecies. This suggests that the non wetting species behaves akin to a\nthree-dimensional bulk system. An appropriate reasoning is presented to justify\nthe given observations."
    },
    {
        "anchor": "Finite amplitude elastic waves propagating in compressible solids: The paper studies the interaction of a longitudinal wave with transverse\nwaves in general isotropic and unconstrained hyperelastic materials, including\nthe possibility of dissipation. The dissipative term chosen is similar to the\nclassical stress tensor describing a Stokesian fluid and is commonly used in\nnonlinear acoustics. The aim of this research is to derive the corresponding\ngeneral equations of motion, valid for any possible form of the strain energy\nfunction and to investigate the possibility of obtaining some general and exact\nsolutions to these equations by reducing them to a set of ordinary differential\nequations. Then the reductions can lead to some exact closed-form solutions for\nspecial classes of materials (here the examples of the Hadamard, Blatz-Ko, and\npower-law strain energy densities are considered, as well as fourth-order\nelasticity). The solutions derived are in a time/space separable form and may\nbe interpreted as generalized oscillatory shearing motions and generalized\nsinusoidal standing waves. By means of standard methods of dynamical systems\ntheory, some peculiar properties of waves propagating in compressible materials\nare uncovered, such as for example, the emergence of destabilizing effects.\nThese latter features exist for highly nonlinear strain energy functions such\nas the relatively simple power-law strain energy, but they cannot exist in the\nframework of fourth-order elasticity.",
        "positive": "Active and Passive Transport of Cargo in a Corrugated Channel: A Lattice\n  Model Study: Inside cells, cargos such as vesicles and organelles are transported by\nmolecular motors to their correct locations via active motion on cytoskeletal\ntracks and passive, Brownian diffusion. During the transportation of cargos,\nmotor-cargo complexes (MCC) navigate the confining and crowded environment of\nthe cytoskeletal network and other macromolecules. Motivated by this, we study\na minimal two-state model of motor-driven cargo transport in confinement and\npredict transport properties that can be tested in experiments. We assume that\nthe motion of the MCC is directly affected by the entropic barrier due to\nconfinement if it is in the passive, unbound state, but not in the active,\nbound state where it moves with a constant bound velocity. We construct a\nlattice model based on a Fokker Planck description of the two-state system,\nstudy it using a kinetic Monte Carlo method and compare our numerical results\nwith analytical expressions for a mean field limit. We find that the effect of\nconfinement strongly depends on the bound velocity and the binding kinetics of\nthe MCC. Confinement effectively reduces the effective diffusivity and average\nvelocity, except when it results in an enhanced average binding rate and\nthereby leads to a larger average velocity than when unconfined."
    },
    {
        "anchor": "Propagating irreversibility fronts in cyclically-sheared suspensions: The interface separating a liquid from its vapor phase is diffuse: the\ncomposition varies continuously from one phase to the other over a finite\nlength. Recent experiments on dynamic jamming fronts in two dimensions\n[Waitukaitis et al., Europhysics Letters 102, 44001 (2013)] identified a\ndiffuse interface between jammed and unjammed discs. In both cases, the\nthickness of the interface diverges as a critical transition is approached. We\ninvestigate the generality of this behavior using a third system: a model of\ncyclically-sheared non-Brownian suspensions. As we sediment the particles\ntowards a boundary, we observe a diffuse traveling front that marks the\ninterface between irreversible and reversible phases. We argue that the front\nwidth is linked to a diverging correlation lengthscale in the bulk, which we\nprobe by studying avalanches near criticality. Our results show how diffuse\ninterfaces may arise generally when an incompressible phase is brought to a\ncritical point.",
        "positive": "A density functional study of the structure of tethered chains in a\n  binary mixture: A density functional study of the structure of a layer formed by chain\nmolecules pinned to a solid surface is presented. The chains are modeled as\nfreely joined spheres. Segments and all components interact via Lennard-Jones\n(12-6) potential. The interactions of fluid molecules with the wall are\ndescribed by the Lennard-Jones (9-3) potential. We analyze how different\nparameters of the model affect the dependence of the brush height upon the\nmixture composition. We consider the effect of grafting density and the\nparameters characterizing the interactions of fluid molecules with the\nsubstrate and with the chains as well as interactions within the mixture. The\nchanges in the brush height correlate with the adsorption of particular\ncomponents."
    },
    {
        "anchor": "Mapping onto ideal chains overestimates self-entanglements in polymer\n  melts: In polymer physics it is typically assumed that excluded volume interactions\nare effectively screened in polymer melts. Hence, chains could be described by\nan effective random walk without excluded volume interactions. In this letter,\nwe show that this mapping is problematic by analyzing the occurrence of knots,\ntheir spectrum and sizes in polymer melts, corresponding random walks and\nchains in dilute solution. The effective random walk severely overrates the\noccurrence of knots and their complexity, particularly when compared to melts\nof flexible chains, indicating that non-trivial effects due to remnants of\nself-avoidance still play a significant role for the chain lengths considered\nin this numerical study. For melts of semiflexible chains, the effect is less\npronounced. In addition, we find that chains in a melt are very similar in\nstructure and topology to dilute single chains close to the collapse\ntransition, which indicates that the latter are also not well-represented by\nrandom walks. We finally show that typical equilibration procedures are\nwell-suited to relax the topology in melts.",
        "positive": "The effect of chain polydispersity on the elasticity of disordered\n  polymer networks: Due to their unique structural and mechanical properties,\nrandomly-crosslinked polymer networks play an important role in many different\nfields, ranging from cellular biology to industrial processes. In order to\nelucidate how these properties are controlled by the physical details of the\nnetwork (\\textit{e.g.} chain-length and end-to-end distributions), we generate\ndisordered phantom networks with different crosslinker concentrations $C$ and\ninitial density $\\rho_{\\rm init}$ and evaluate their elastic properties. We\nfind that the shear modulus computed at the same strand concentration for\nnetworks with the same $C$, which determines the number of chains and the\nchain-length distribution, depends strongly on the preparation protocol of the\nnetwork, here controlled by $\\rho_{\\rm init}$. We rationalise this dependence\nby employing a generic stress-strain relation for polymer networks that does\nnot rely on the specific form of the polymer end-to-end distance distribution.\nWe find that the shear modulus of the networks is a non-monotonic function of\nthe density of elastically-active strands, and that this behaviour has a purely\nentropic origin. Our results show that if short chains are abundant, as it is\nalways the case for randomly-crosslinked polymer networks, the knowledge of the\nexact chain conformation distribution is essential for predicting correctly the\nelastic properties. Finally, we apply our theoretical approach to published\nexperimental data, qualitatively confirming our interpretations."
    },
    {
        "anchor": "Efficient tunable generic model for fluid bilayer membranes: We present a model for the efficient simulation of generic bilayer membranes.\nIndividual lipids are represented by one head- and two tail-beads. By means of\nsimple pair potentials these robustly self-assemble to a fluid bilayer state\nover a wide range of parameters, without the need for an explicit solvent. The\nmodel shows the expected elastic behavior on large length scales, and its\nphysical properties (eg fluidity or bending stiffness) can be widely tuned via\na single parameter. In particular, bending rigidities in the experimentally\nrelevant range are obtained, at least within $3-30 k_{\\text{B}}T$. The model is\nnaturally suited to study many physical topics, including self-assembly,\nfusion, bilayer melting, lipid mixtures, rafts, and protein-bilayer\ninteractions.",
        "positive": "Using electrowetting to control interface motion in patterned\n  microchannels: We use mesoscale simulations to demonstrate the feasibility of a novel\nmicrofluidic valve, which exploits Gibbs' pinning in microchannels patterned by\nposts or ridges, together with electrowetting."
    },
    {
        "anchor": "Characterizing 1D Inertial Particle Clustering: Clustering is an important phenomenon in turbulent flows laden with inertial\nparticles. Although this process has been studied extensively, there are still\nopen questions about both the fundamental physics and the reconciliation of\ndifferent observations into a coherent quantitative view of this important\nmechanism for particle-turbulence interaction. In this work, we study the\neffect of projecting this phenomenon onto 2D and 1D (as usually done in\nexperiments). In particular, the effect of measurement volume in 1D projections\non detected cluster properties, such as size or concentration, is explored to\nprovide a method for comparison of published/future observations, from\nexperimental or numerical data. The results demonstrate that, in order to\ncapture accurate values of the mean cluster properties under a wide range of\nexperimental conditions, the measurement volume needs to be larger than the\nKolmogorov length scale, and smaller than about ten percent of the integral\nlength scale of the turbulence. This dependency provides the correct scaling to\ncarry out 1D measurements of preferential concentration, considering the\nturbulence characteristics. It is also critical to disentangle the\ncluster-characterizing results from random contributions to the cluster\nstatistics, especially in 1D, as the raw probability density function of\nVoronoi cells does not provide error-free information on the clusters size or\nlocal concentration. We propose a methodology to correct for this measurement\nbias, with an analytical model of the cluster PDF obtained from comparison with\na Random Poisson Process probability distribution in 1D, which appears to\ndiscard the existence of power laws in the cluster PDF. We develop a new test\nto discern between turbulence-driven clustering and randomness, that\ncomplements the cluster identification algorithm by segregating the number of\nparticles inside each cluster.",
        "positive": "Hierarchical bounding structures for efficient virial computations:\n  Towards a realistic molecular description of cholesterics: We detail the application of bounding volume hierarchies to accelerate\nsecond-virial evaluations for arbitrary complex particles interacting through\nhard and soft finite-range potentials. This procedure, based on the\nconstruction of neighbour lists through the combined use of recursive\natom-decomposition techniques and binary overlap search schemes, is shown to\nscale sub-logarithmically with particle resolution in the case of molecular\nsystems with high aspect ratios. Its implementation within an efficient\nnumerical and theoretical framework based on classical density functional\ntheory enables us to investigate the cholesteric self-assembly of a wide range\nof experimentally-relevant particle models. We illustrate the method through\nthe determination of the cholesteric behaviour of hard, structurally-resolved\ntwisted cuboids, and report quantitative evidence of the long-predicted phase\nhandedness inversion with increasing particle thread angles near the\nphenomenological threshold value of $45^\\circ$. Our results further highlight\nthe complex relationship between microscopic structure and helical twisting\npower in such model systems, which may be attributed to subtle geometric\nvariations of their chiral excluded-volume manifold."
    },
    {
        "anchor": "Dynamic control of self-assembly of quasicrystalline structures through\n  reinforcement learning: We propose reinforcement learning to control the dynamical self-assembly of\nthe dodecagonal quasicrystal (DDQC) from patchy particles. The patchy particles\nhave anisotropic interactions with other particles and form DDQC. However,\ntheir structures at steady states are significantly influenced by the kinetic\npathways of their structural formation. We estimate the best policy of\ntemperature control trained by the Q-learning method and demonstrate that we\ncan generate DDQC with few defects using the estimated policy. The temperature\nschedule obtained by reinforcement learning can reproduce the desired structure\nmore efficiently than the conventional pre-fixed temperature schedule, such as\nannealing. To clarify the success of the learning, we also analyse a simple\nmodel describing the kinetics of structural changes through the motion in a\ntriple-well potential. We have found that reinforcement learning autonomously\ndiscovers the critical temperature at which structural fluctuations enhance the\nchance of forming a globally stable state. The estimated policy guides the\nsystem toward the critical temperature to assist the formation of DDQC.",
        "positive": "Wetting of an Ising system with perfect and corrugated surfaces in a\n  transverse field: Using the mean field theory, a comparative study of the wetting and layering\ntransitions of a spin-1/2 Ising model with perfect and corrugated surfaces, is\nestablished. The phase diagrams are investigated and compared in the presence\nof both a longitudinal and surface fields. The effect of increasing the\ntemperature and the transverse field on the wetting and layering transitions is\noutlined."
    },
    {
        "anchor": "Transport and phase separation of active Brownian particles in\n  fluctuating environments: In this work, we study the dynamics of a single active Brownian particle, as\nwell as the collective behavior of interacting active Brownian particles, in a\nfluctuating heterogeneous environment. We employ a variant of the diffusing\ndiffusivity model where the equation of motion of the active particle involves\na time-dependent motility and diffusivities. Within our model, those\nfluctuations are coupled to each other. Using analytical methods, we obtain the\nprobability distribution function of particle displacement and its moments for\na single particle. We then investigate the impact of the environmental\nfluctuations on the collective behavior of the active Brownian particles by\nmeans of extensive numerical simulations. Our results show that the\nfluctuations hinder the motility-induced phase separation, accompanied by a\nsignificant change of the density dependence of particle velocities. These\neffects are interpreted using our analytical results for the dynamics of a\nsingle particle.",
        "positive": "Complete absorption of topologically protected waves: Chiral edge states can transmit energy along imperfect interfaces in a\ntopologically robust and unidirectional manner when protected by bulk-boundary\ncorrespondence. However, in continuum systems, the number of states at an\ninterface can depend on boundary conditions. Here we design interfaces that\nhost a net flux of the number of modes into a region, trapping incoming energy.\nAs a realization, we present a model system of two topological fluids composed\nof counter-spinning particles, which are separated by a boundary that\ntransitions from a fluid-fluid interface into a no-slip wall. In these fluids,\nchiral edge states disappear, which implies non-Hermiticity and leads to a\nnovel interplay between topology and energy dissipation. Solving the fluid\nequations of motion, we find explicit expressions for the disappearing modes.\nWe then conclude that energy dissipation is sped up by mode trapping. Instead\nof making efficient waveguides, our work shows how topology can be exploited\nfor applications towards acoustic absorption, shielding, and soundproofing."
    },
    {
        "anchor": "Half-integer and full-integer topological defects in polar active\n  matter: Emergence, crossover, and coexistence: The presence and significance of active topological defects is increasingly\nrealised in diverse biological and biomimetic systems. We introduce a continuum\nmodel of polar active matter, based on conservation laws and symmetry\narguments, that recapitulates both polar and apolar (nematic) features of\ntopological defects in active turbulence. Using numerical simulations of the\ncontinuum model, we demonstrate the emergence of both half- and full-integer\ntopological defects in polar active matter. Interestingly, we find that\ncrossover from active turbulence with half- to full-integer defects can emerge\nwith the coexistence region characterized by both defect types. These results\nput forward a minimal, generic framework for studying topological defect\npatterns in active matter which is capable of explaining the emergence of\nhalf-integer defects in polar systems such as bacteria and cell monolayers, as\nwell as predicting the emergence of coexisting defect states in active matter.",
        "positive": "DNA unzipping phase diagram calculated via replica theory: We show how single-molecule unzipping experiments can provide strong evidence\nthat the zero-force melting transition of long molecules of natural dsDNA\nshould be classified as a phase transition of the higher-order type\n(continuous). We study a model for a long molecule of dsDNA, and compute the\nequilibrium phase diagram for the experiment in which the molecule is unzipped\nunder force. We consider a perfect-matching dsDNA model, in which the loops are\nvolume-excluding chains with arbitrary loop exponent c. We include stacking\ninteractions, hydrogen bonds, and main-chain entropy, including sequence\nheterogeneity at the level of random sequences. We use the replica method to\ncalculate the equilibrium properties of the system. As a function of\ntemperature, we obtain the minimal force at which the molecule separates\ncompletely. This critical force curve is a line in the temperature-force phase\ndiagram that marks the regions where the molecule exists primarily as a helix,\nversus the region where the molecule exists as two separate strands. Near\nmelting, the critical force curve of our random-sequence model is very\ndifferent from that of the homogeneous version of our model. For both sequence\nmodels, the critical force falls to zero at the melting temperature with a\npower law having exponent alpha. For the homogeneous model, alpha is 1/2 almost\nexactly, while for the random model, alpha is about 0.9. The shape of the\ncritical force determines how the helix fraction falls to zero at melting, and\nthus classifies the melting transition as a type of phase transition."
    },
    {
        "anchor": "Brownian motion of a self-propelled particle: Overdamped Brownian motion of a self-propelled particle is studied by solving\nthe Langevin equation analytically. On top of translational and rotational\ndiffusion, in the context of the presented model, the \"active\" particle is\ndriven along its internal orientation axis. We calculate the first four moments\nof the probability distribution function for displacements as a function of\ntime for a spherical particle with isotropic translational diffusion as well as\nfor an anisotropic ellipsoidal particle. In both cases the translational and\nrotational motion is either unconfined or confined to one or two dimensions. A\nsignificant non-Gaussian behavior at finite times t is signalled by a\nnon-vanishing kurtosis. To delimit the super-diffusive regime, which occurs at\nintermediate times, two time scales are identified. For certain model\nsituations a characteristic t^3 behavior of the mean square displacement is\nobserved. Comparing the dynamics of real and artificial microswimmers like\nbacteria or catalytically driven Janus particles to our analytical expressions\nreveals whether their motion is Brownian or not.",
        "positive": "Anatomy of cage formation in a 2D glass-forming liquid: The solidity of glassy materials is believed to be due to the cage formed\naround each particle by its neighbors, but in reality the details of\ncage-formation remain elusive [1-4]. This cage starts to be formed at the onset\ntemperature/density at which the normal liquid begins to show the first signs\nof glassy dynamics. To study cage-formation we use here focused lasers to\nproduce a local perturbation of the structure on the particle level in 2D\ncolloidal suspensions and monitor by means of video microscopy the system's\nnon-linear dynamic response. All observables we probed show a response which is\nnon-monotonic as a function of the packing fraction, peaking at the onset\ndensity. Video microscopic images reveal that this maximum response is due to\nthe buildup of domains with cooperative dynamics that become increasingly rigid\nand start to dominate the particle dynamics. This proof-of-concept from\nmicrorheological deformation demonstrates that in this glass-forming liquid\ncage formation is directly related to the merging of these domains, thus\nelucidating the first step in glass-formation [1, 5]."
    },
    {
        "anchor": "Electric-Field Induced Phase Transitions in Capillary Electrophoretic\n  Systems: The movement of the particles in a capillary electrophoretic system under\nelectroosmotic flow was modeled using Monte Carlo simulation with Metropolis\nalgorithm. Two different cases, with repulsive and attractive interactions\nbetween molecules were taken into consideration. The simulation was done using\na spin-like system where the interactions between the nearest and second\nclosest neighbors were considered in two separate steps of the modeling study.\nA total of 20 different cases with different rate of interactions for both\nrepulsive and attractive interactions were modeled. The movement of the\nparticles through the capillary is defined as current. At a low interaction\nlevel between molecules, a regular electroosmotic flow is obtained, on the\nother hand, with increasing interactions between molecules the current shows a\nphase transition behavior. The results also show that a modular electroosmotic\nflow can be obtained for separations by tuning the ratio between molecular\ninteractions and electric field strength.",
        "positive": "1-d granular gas with little dissipation in 0-g : A comment on\n  \"Resonance oscillations in Granular gases\": It is demonstrated that recent results on 1d granular gas in a container with\na vibrating piston, which was modelled by a shock wave propagation, can be\nunderstood with a modelling using ideas coming from the \"thermodynamics of a\nsingle particle\". Defining e as the square root of the energetic-restitution\ncoefficient of a single collision, and N as the total number of grains, the\nmean loss during a round trip of the momentum is calculated in the limit\nN(1-e)<<1. It is also demonstrated that the system cannot propagate sound waves\nnor shock waves in the limit of N(1-e)<<1 and that hydrodynamics equations\ncannot be defined when N(1-e)<<1. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn"
    },
    {
        "anchor": "Predicting the morphology of multiphase biomolecular condensates from\n  protein interaction networks: Phase-separated biomolecular condensates containing proteins and RNAs can\nassemble into higher-order structures by forming thermodynamically stable\ninterfaces between immiscible phases. Using a minimal model of a protein/RNA\ninteraction network, we demonstrate how a \"shared\" protein species that\npartitions into both phases of a multiphase condensate can function as a\ntunable surfactant that modulates the interfacial properties. We use Monte\nCarlo simulations and free-energy calculations to identify conditions under\nwhich a low concentration of this shared species is sufficient to trigger a\nwetting transition. We also describe a numerical approach based on classical\ndensity functional theory to predict concentration profiles and surface\ntensions directly from the model protein/RNA interaction network. Finally, we\nshow that the wetting phase diagrams that emerge from our calculations can be\nunderstood in terms of a simple model of selective adsorption to a fluctuating\ninterface. Our work shows how a low-concentration protein species might\nfunction as a biological switch for regulating multiphase condensate\nmorphologies.",
        "positive": "Dynamical patterns in active nematics on a sphere: Using agent-based simulations of self-propelled particles subject to\nshort-range repulsion and nematic alignment we explore the dynamical phases of\na dense active material confined to the surface of a sphere. We map the\ndynamical phase diagram as a function of curvature, alignment strength and\nactivity and reproduce phases seen in recent experiments on active microtubules\nmoving on the surfaces of vesicles. At low driving, we recover the equilibrium\nnematic ground state with four +1/2 defects. As the driving is increased,\ngeodesic forces drive the transition to a band of polar matter wrapping around\nan equator, with large bald spots corresponding to two +1 defects at the poles.\nFinally, bands fold onto themselves, followed by the system moving into a\nturbulent state marked by active proliferation of pairs of topological defects.\nWe highlight the role of nematic persistence length and time for pattern\nformation in these confined systems with finite curvature."
    },
    {
        "anchor": "Critical Scaling of Shearing Rheology at the Jamming Transition of Soft\n  Core Frictionless Disks: We perform numerical simulations to determine the shear stress and pressure\nof steady-state shear flow in a soft-disk model in two dimensions at zero\ntemperature in the vicinity of the jamming transition \\phi_J. We use critical\npoint scaling analyses to determine the critical behavior at jamming, and we\nfind that it is crucial to include corrections to scaling for a reliable\nanalysis. We find that the relative size of these corrections are much smaller\nfor pressure than for shear stress. We furthermore find a superlinear behavior\nfor pressure and shear stress above \\phi_J, both from the scaling analysis and\nfrom a direct analysis of pressure data extrapolated to the limit of vanishing\nshear rate.",
        "positive": "An entropic effect essential for surface entrapment of bacteria: The entrapment of bacteria near boundary surfaces is of biological and\npractical importance, yet the underlying physics is still not well understood.\nWe demonstrate that it is crucial to include a commonly neglected entropic\neffect arising from the spatial variation of hydrodynamic interactions, through\na model that provides analytic explanation of bacterial entrapment in two\ndimensionless parameters: $\\alpha_1$ the ratio of thermal energy to\nself-propulsion, and $\\alpha_2$ an intrinsic shape factor. For $\\alpha_1$ and\n$\\alpha_2$ that match an {\\it Escherichia coli} at room temperature, our model\nquantitatively reproduces existing experimental observations, including two key\nfeatures that have not been previously resolved: The bacterial \"nose-down\"\nconfiguration, and the anticorrelation between the pitch angle and the wobbling\nangle. Furthermore, our model analytically predicts the existence of an\nentrapment zone in the parameter space defined by $\\{\\alpha_1,\\alpha_2\\}$."
    },
    {
        "anchor": "Inhomogeneous transport in model hydrated polymer electrolyte supported\n  ultra-thin films: Structure of polymer electrolytes membranes, e.g., Nafion, inside fuel cell\ncatalyst layers has significant impact on the electrochemical activity and\ntransport phenomena that determine cell performance. In those regions, Nafion\ncan be found as an ultra-thin film, coating the catalyst and the catalyst\nsupport surfaces. The impact of the hydrophilic/hydrophobic character of these\nsurfaces on the structural formation of the films and, in turn, on transport\nproperties, has not been sufficiently explored yet. Here, we report about\nclassical Molecular Dynamics simulations of hydrated Nafion thin-films in\ncontact with unstructured supports, characterized by their global wetting\nproperties only. We have investigated structure and transport in different\nregions of the film and found evidences of strongly heterogeneous behavior. We\nspeculate about the implications of our work on experimental and technological\nactivity.",
        "positive": "Thermodynamic consistency of third grade finite strain elasticity: Thermodynamic framework of finite strain viscoelasticity with second order\nweak nonlocality in the deformation gradient is investigated. The application\nof Liu procedure leads to a class of third grade elastic materials where the\nsecond gradient of the stress appears in the elastic constitutive relation.\nFinally the dispersion relation of longitudinal plane waves is calculated in\nisotropic materials."
    },
    {
        "anchor": "Lipids and lipid-mixtures in boundary layers: from hydration lubrication\n  to osteoarthritis: The hydration layer surrounding the phosphocholine headgroups of\nsingle-component phosphatidylcholine (PC) lipids, or of lipid-mixtures,\nassembled at an interface greatly modifies the interfacial properties and\ninteractions. As water molecules within the hydration layer are held tightly by\nthe headgroup but are nonetheless very fluid upon shear, the boundary lipid\nlayers, exposing the highly hydrated headgroup arrays, can provide efficient\nboundary lubrication when sliding against an opposing surface, at\nphysiologically-high contact pressures. Additionally, any free lipids in the\nsurrounding liquid can heal defects which may form during sliding on the\nboundary PC layer. Similar boundary lipid layers contribute to the lubricating,\npressure-bearing, and wear-protection functions of healthy articular joints.\nThis review presents a survey of the relationship between the molecular\ncomposition of the interfacial complex and the lubrication behavior of the\nlipid-based boundary layers, which could be beneficial for designing boundary\nlubricants for intra-articular injection for the treatment of early OA.",
        "positive": "Motility-induced temperature difference in coexisting phases: In nature, objects which are in thermal contact with each other, usually\napproach the same temperature, unless a heat source (or sink) cherishes a\npersistent flow of heat. Accordingly, in a well-isolated apartment flat, most\nitems are at a similar temperature. This is a general consequence of\nequilibrium thermodynamics, requiring coexisting phases to have identical\ntemperatures. Opposing this generic situation, here we identify a system\nshowing different temperatures in coexisting phases, which are separated from\neach other by a sharp and persistent temperature gradient. Thermodynamically,\nsuch a \"hot\" and a \"cold\" phase are allowed to coexist, as the system we\nconsider comprises \"active\" particles which self-propel relative to their\nenvironment and are thus intrinsically out-of-equilibrium. Although these\nmicroparticles are well known to spontaneously phase-separate into a liquid-\nand a gas-like state, different kinetic temperatures in coexisting phases occur\nif and only if inertia is introduced, which is neglected in standard models\ndescribing active particles. Our results, therefore, exemplify a novel route to\nuse active particles to create a self-sustained temperature gradient across\ncoexisting phases, a phenomenon, which is fundamentally beyond equilibrium\nphysics."
    },
    {
        "anchor": "Remarkably strong magnetic response in molecules with polar groups: For more than a century, electricity and magnetism have been believed to\nalways exhibit inextricable link due to the symmetry in electromagnetism. At\nthe interface, polar groups that have polar charges, are indispensable to be\nconsidered, which interact directly with other polar charges/external\ncharges/external electric fields. However, there is no report on the\ncorresponding magnetic properties on these polar groups. Clearly, such\nasymmetry, that is, only the interaction between the polar groups and charges,\nis out of bounds. Here we show that those molecules with considerable polar\ngroups, such as cellulose acetate (CA) and other cellulose derivatives with\ndifferent polar groups, can have strong magnetic response, indicating that they\nare strongly paramagnetic. Density functional theory (DFT) calculation shows\nthat the polarity greatly reduces the excitation energy from the state without\nnet spin (singlet) to the state with net spin (triplet), making the\nconsiderable existence of magnetic moments on the polar groups. We note that\nthe hydrophobic groups in these molecules have no magnetic moments, however,\nthey make the molecules aggregate to amply the magnetic effect of the magnetic\nmoments in the polar groups, so that these magnetic moments can induce the\nstrong paramagnetism. Our observations suggest a recovery of the symmetry with\ninextricable link between the electricity and magnetism at the interface. The\nfindings leave many imaginations of the role of the magnetic interaction in\nbiological systems as well as other magnetic applications considering that many\nof those polar materials are biological materials, pharmaceutical materials,\nchemical raw materials, and even an essential hormone in agricultural\nproduction.",
        "positive": "Proposition of extension of models relating rheological quantities and\n  microscopic structure through the use of a double fractal structure: Colloidal suspensions and the relation between their rheology and their\nmicrostructure is investigated. The literature showed great evidence of the\nrelation between rheological quantities and particle volume fraction, ignoring\nthe influence of the cluster. We propose to extend previous models using a new\ndouble fractal structure which allows, first, to recover the well-known models\non the case of percolated system and, second, to capture the influence of the\ncluster size. This new model emphasises the necessity of such structure to\naccount for recent experimental results. Then, the model is compared with data\ncoming from the literature and shows close agreement."
    },
    {
        "anchor": "Recovering the activity parameters of an active fluid confined in a\n  sphere: The properties of an active fluid, for example, a bacterial bath or a\ncollection of microtubules and molecular motors, can be accessed through the\ndynamics of passive particle probes. Here, in the perspective of analyzing\nexperimental situations of confinement in droplets, we consider the kinematics\nof a negatively buoyant probe particle in an active fluid, both confined within\na spherical domain. The active bath generates a fluctuating flow that pushes\nthe particle with a velocity that is modeled as a colored stochastic noise,\ncharacterized by two parameters, the intensity and memory time of the active\nflow. When the particle departs a little from the bottom of the spherical\ndomain, the configuration is well approximated by a particle in a\ntwo-dimensional harmonic trap subjected to the colored noise, in which case an\nanalytical solution exists, which is the base for quantitative analysis. We\nnumerically simulate the dynamics of the particle and use the planar,\ntwo-dimensional mean square displacement to recover the activity parameters of\nthe bath. This approach yields satisfactory results as long as the particle\nremains relatively confined, that is, as long as the intensity of the colored\nnoise remains low.",
        "positive": "Shearing effects on the phase coarsening of binary mixtures using the\n  Active Model B: The phase separation of a two-dimensional active binary mixture is studied\nunder the action of an applied shear through numerical simulations. It is\nhighlighted how the strength of the external flow modifies the initial shape of\ngrowing domains. The activity is responsible for the formation of isolated\ndroplets which affect both the coarsening dynamics and the morphology of the\nsystem. The characteristic dimensions of domains along the flow and the shear\ndirection are modulated in time by oscillations whose amplitudes are reduced\nwhen the activity increases. This induces a broadening of the distribution\nfunctions of domain lengths with respect to the passive case due to the\npresence of dispersed droplets of different sizes."
    },
    {
        "anchor": "Squeezing and temperature measurement in Bose-Einstein Condensates: In this paper we discuss the presence of temperature-dependent squeezing in\nthe collective excitations of trapped Bose-Einstein condensates, based on a\nrecent theory of quasiparticle damping. A new scheme to measure temperature\nbelow the critical temperature is also considered.",
        "positive": "Layering Transitions and Solvation Forces in an Asymmetrically Confined\n  Fluid: We consider a simple fluid confined between two parallel walls (substrates),\nseparated by a distance L. The walls exert competing surface fields so that one\nwall is attractive and may be completely wet by liquid (it is solvophilic)\nwhile the other is solvophobic. Such asymmetric confinement is sometimes termed\na `Janus Interface'. The second wall is: (i) purely repulsive and therefore\ncompletely dry (contact angle 180 degrees) or (ii) weakly attractive and\npartially dry (the contact angle is typically in the range 160-170 degrees). At\nlow temperatures, but above the bulk triple point, we find using classical\ndensity functional theory (DFT) that the fluid is highly structured in the\nliquid part of the density profile. In case (i) a sequence of layering\ntransitions occurs: as L is increased at fixed chemical potential (mu) close to\nbulk gas--liquid coexistence, new layers of liquid-like density develop\ndiscontinuously. In contrast to confinement between identical walls, the\nsolvation force is repulsive for all wall separations and jumps discontinuously\nat each layering transition and the excess grand potential exhibits many\nmetastable minima as a function of the adsorption. For a fixed temperature\nT=0.56Tc, where Tc is the bulk critical temperature, we determine the\ntransition lines in the L, mu plane. In case (ii) we do not find layering\ntransitions and the solvation force oscillates about zero. We discuss how our\nmean-field DFT results might be altered by including effects of fluctuations\nand comment on how the phenomenology we have revealed might be relevant for\nexperimental and simulation studies of water confined between hydrophilic and\nhydrophobic substrates, emphasizing it is important to distinguish between\ncases (i) and (ii)."
    },
    {
        "anchor": "Complex free energy landscapes in biaxial nematics and role of repulsive\n  interactions : A Wang - Landau study: General quadratic Hamiltonian models, describing interaction between crystal\nmolecules (typically with $D_{2h}$ symmetry) take into account couplings\nbetween their uniaxial and biaxial tensors. While the attractive contributions\narising from interactions between similar tensors of the participating\nmolecules provide for eventual condensation of the respective orders at\nsuitably low temperatures, the role of cross-coupling between unlike tensors is\nnot fully appreciated. Our recent study with an advanced Monte Carlo technique\n(entropic sampling) showed clearly the increasing relevance of this cross term\nin determining the phase diagram, contravening in some regions of model\nparameter space, the predictions of mean field theory and standard Monte Carlo\nsimulation results. In this context, we investigated the phase diagrams and the\nnature of the phases therein, on two trajectories in the parameter space: one\nis a line in the interior region of biaxial stability believed to be\nrepresentative of the real systems, and the second is the extensively\ninvestigated parabolic path resulting from the London dispersion approximation.\nIn both the cases, we find the destabilizing effect of increased cross-coupling\ninteractions, which invariably result in the formation of local biaxial\norganizations inhomogeneously distributed. This manifests as a small, but\nunmistakable, contribution of biaxial order in the uniaxial phase.The free\nenergy profiles computed in the present study as a function of the two dominant\norder parameters indicate complex landscapes, reflecting the difficulties in\nthe ready realization of the biaxial phase in the laboratory.",
        "positive": "Influence of hydrodynamic interactions on stratification in drying\n  mixtures: Nonequilibrium molecular dynamics simulations are used to investigate the\ninfluence of hydrodynamic interactions on vertical segregation (stratification)\nin drying mixtures of long and short polymer chains. In agreement with previous\ncomputer simulations and theoretical modeling, the short polymers stratify on\ntop of the long polymers at the top of the drying film when hydrodynamic\ninteractions between polymers are neglected. However, no stratification occurs\nat the same drying conditions when hydrodynamic interactions are incorporated\nthrough an explicit solvent model. Our analysis demonstrates that models\nlacking hydrodynamic interactions do not faithfully represent stratification in\ndrying mixtures, in agreement with recent analysis of an idealized model for\ndiffusiophoresis, and must be incorporated into such models in future."
    },
    {
        "anchor": "Disentangling Entanglements in Biopolymer Solutions: Reptation theory has been highly successful in explaining the unusual\nmaterial properties of entangled polymer solutions. It reduces the complex\nmany-body dynamics to a single-polymer description where each polymer is\nenvisaged to be confined to a tube through which it moves in a snake-like\nfashion. For flexible polymers, reptation theory has been amply confirmed by\nboth experiments and simulations. In contrast, for semiflexible polymers\nexperimental and numerical tests are either limited to the onset of reptation,\nor were performed for tracer polymers in a fixed, static matrix. Here we report\nBrownian dynamics simulations of entangled solutions of semiflexible polymers,\nwhich show that curvilinear motion along a tube (reptation) is no longer the\ndominant mode of dynamics. Instead, we find that polymers disentangle due to\ncorrelated constraint release which leads to equilibration of internal bending\nmodes before polymers diffuse the full tube length. The physical mechanism\nunderlying terminal stress relaxation is rotational diffusion mediated by\ndisentanglement rather than curvilinear motion along a tube.",
        "positive": "Structure, stability and elasticity of DNA nanotube: DNA nanotubes are tubular structures composed of DNA crossover molecules. We\npresent a bottom up approach for construction and characterization of these\nstructures. Various possible topologies of nanotubes are constructed such as\n6-helix, 8-helix and tri-tubes with different sequences and lengths. We have\nused fully atomistic molecular dynamics simulations to study the structure,\nstability and elasticity of these structures. Several nanosecond long MD\nsimulations give the microscopic details about DNA nanotubes. Based on the\nstructural analysis of simulation data, we show that 6-helix nanotubes are\nstable and maintain their tubular structure; while 8-helix nanotubes are\nflattened to stabilize themselves. We also comment on the sequence dependence\nand effect of overhangs. These structures are approximately four times more\nrigid having stretch modulus of ~4000 pN compared to the stretch modulus of\n1000 pN of DNA double helix molecule of same length and sequence. The stretch\nmoduli of these nanotubes are also three times larger than those of PX/JX\ncrossover DNA molecules which have stretch modulus in the range of 1500-2000\npN. The calculated persistence length is in the range of few microns which is\nclose to the reported experimental results on certain class of the DNA\nnanotubes."
    },
    {
        "anchor": "Topological persistence and dynamical heterogeneities near jamming: We introduce topological methods for quantifying spatially heterogeneous\ndynamics, and use these tools to analyze particle-tracking data for a\nquasi-two-dimensional granular system of air-fluidized beads on approach to\njamming. In particular we define two overlap order parameters, which quantify\nthe correlation between particle configurations at different times, based on a\nVoronoi construction and the persistence in the resulting cells and nearest\nneighbors. Temporal fluctuations in the decay of the persistent area and bond\norder parameters define two alternative dynamic four-point susceptibilities,\nXA(t) and XB(t), well-suited for characterizing spatially-heterogeneous\ndynamics. These are analogous to the standard four-point dynamic susceptibility\nX4(l,t), but where the space-dependence is fixed uniquely by topology rather\nthan by discretionary choice of cutoff function. While these three\nsusceptibilities yield characteristic time scales that are somewhat different,\nthey give domain sizes for the dynamical heterogeneities that are in good\nagreement and that diverge on approach to jamming.",
        "positive": "Melting-freezing cycles in a relatively sheared pair of crystalline\n  monolayers: The nonequilibrium dynamical behaviour that arises when two ordered\ntwo-dimensional monolayers of particles are sheared over each other is studied\nin Brownian dynamics simulations. A curious sequence of nonequilibrium states\nis observed as the driving rate is increased, the most striking of which is a\nsliding state with irregular alternation between disordered and ordered states.\nWe comment on possible mechanisms underlying these cycles, and experiments that\ncould observe them."
    },
    {
        "anchor": "Renormalized charge in a two-dimensional model of colloidal suspension\n  from hypernetted chain approach: The renormalized charge of a simple two-dimensional model of colloidal\nsuspension was determined by solving the hypernetted chain approximation and\nOrnstein-Zernike equations. At the infinite dilution limit, the asymptotic\nbehavior of the correlations functions is used to define the effective\ninteractions between the components of the system and these effective\ninteractions were compared to those derived from the Poisson-Boltzmann theory.\nThe results we obtained show that, in contrast to the mean-field theory, the\nrenormalized charge does not saturate, but exhibits a maximum value and then\ndecays monotonically as the bare charge increases. The results also suggest\nthat beyond the counterion layer near to the macroion surface, the ionic cloud\nis not a diffuse layer which can be handled by means of the linearized theory,\nas the two-state model claims, but a more complex structure is settled by the\ncorrelations between microions.",
        "positive": "Revisiting the Poisson-Boltzmann theory: charge surfaces, multivalent\n  ions and inter-plate forces: The Poisson-Boltzmann (PB) theory is extensively used to gain insight on\ncharged colloids and biological systems as well as to elucidate fundamental\nproperties of intermolecular forces. Many works were devoted in the past to\nstudy PB related features and to confirm them experimentally. In this work we\nexplore the properties of inter-plate forces in terms of different boundary\nconditions. We treat the cases of constant surface charge, constant surface\npotential and mixed boundaries. The interplay between electrostatic\ninteractions, attractive counter-ions release, and repulsive van 't Hoff\ncontribution are discussed separately for each case. Finally, we discuss how\nthe crossover between attractive and repulsive interactions for constant\nsurface charge case is influenced by the presence of multivalent counter-ions,\nwhere it is shown that the range of the attractive interaction grows with the\nvalency."
    },
    {
        "anchor": "Temperature of systems out of thermodynamic equilibrium: Two phenomenological approaches are currently used in the study of the\nvitreous state. One is based on the concept of fictive temperature introduced\nby Tool [Jour. Research Nat. Bur. Standards 34, 199 (1945)] and recently\nrevisited by Nieuwenhuizen [Phys. Rev. Lett. 80, 5580 (1998)]. The other is\nbased on the thermodynamics of irreversible processes initiated by De Donder at\nthe beginning of the last century [L'Affinit\\'e (Gauthier-Villars, Paris,\n1927)] and recently used by M\\\"oller and co-workers for a thorough study of the\nglass transition [J. Chem. Phys. 125, 094505 (2006)]. This latter approach\nleads to the possibility of describing the glass transition by means of the\nfreezing-in of one or more order parameters connected to the internal\nstructural degrees of freedom involved in the vitrification process. In this\npaper, the equivalence of the two preceding approaches is demonstrated, not\nonly for glasses, but in a very general way for any system undergoing an\nirreversible transformation. This equivalence allows the definition of an\neffective temperature for all systems departed from equilibrium generating a\npositive amount of entropy. In fact, the initial fictive temperature concept of\nTool leads to the generalization of the notion of temperature for systems out\nof thermodynamic equilibrium, for which glasses are just particular cases.",
        "positive": "Elastic Instabilities in Flows through Pillared Micro channels: Viscoelastic fluids exhibit elastic instabilities in simple shear flow and\nflow through curved streamlines. Surprisingly, we found in a porous medium such\nfluids show strikingly different hydrodynamic instabilities depicted by very\nlarge sideways excursions and presence of fast and slow moving lanes which have\nnot been reported before. Particle image velocimetry (PIV) measurements through\na pillared microchannel, provide experimental evidence of such instabilities at\nvery low Reynolds number (< 0.01). We observe a transition from a symmetric\nlaminar to an asymmetric flow, which finally transforms to a nonlinear\naperiodic flow with strong lateral movements. The instability is characterized\nby a rapid increase in spatial and temporal fluctuations of velocity components\nand pressure at a critical Deborah number (De). Our experiments reveal the\npresence of a fascinating interplay between pore space and fluid rheology."
    },
    {
        "anchor": "A colloidal time crystal and its tempomechanical properties: The spontaneous breaking of symmetries is a widespread phenomenon in physics.\nWhen time translational symmetry is spontaneously broken, an exotic\nnonequilibrium state of matter in which the same structures repeat themselves\nin time can arise. This state, known as \"time crystal\", attracted a lot of\ninterest recently. Another relatively new research area deals with active\nmatter. Materials consisting of colloidal particles that consume energy from\ntheir environment and propel themselves forward can exhibit intriguing\nproperties like superfluidity that were previously known only from\nquantum-mechanical systems. Here, we bring together these - at first glance\ncompletely different - research fields by showing that self-propelled colloidal\nparticles can form classical continuous time crystals. We present a state\ndiagram showing where this new state of matter arises. Furthermore, we\ninvestigate its tempomechanical properties and present a temporal stress-strain\ndiagram showing parallels to conventional materials science but also remarkable\nnew properties that do not have a counterpart in common materials.",
        "positive": "Two- or three-step assembly of banana-shaped proteins coupled with shape\n  transformation of lipid membranes: BAR superfamily proteins have a banana-shaped domain that causes the local\nbending of lipid membranes. We study as to how such a local anisotropic\ncurvature induces effective interaction between proteins and changes the global\nshape of vesicles and membrane tubes using meshless membrane simulations. The\nproteins are modeled as banana-shaped rods strongly adhered to the membrane.\nOur study reveals that the rods assemble via two continuous directional phase\nseparations unlike a conventional two-dimensional phase separation. As the rod\ncurvature increases, in the membrane tube the rods assemble along the azimuthal\ndirection and subsequently along the longitudinal direction accompanied by\nshape transformation of the tube. In the vesicle, in the addition to these two\nassembly processes, further increase in the rod curvature induces tubular\nscaffold formation."
    },
    {
        "anchor": "Equivalence of fluctuation-dissipation and Edwards' temperature in\n  cyclically sheared granular systems: Using particle trajectory data obtained from x-ray tomography, we determine\ntwo kinds of effective temperatures in a cyclically sheared granular system.\nThe first one is obtained from the fluctuation-dissipation theorem which\nrelates the diffusion and mobility of lighter tracer particles immersed in the\nsystem. The second is the Edwards compactivity defined via the packing volume\nfluctuations. We find robust excellent agreement between these two\ntemperatures, independent of the type of the tracers, cyclic shear amplitudes,\nand particle surface roughness. We further elucidate that in granular systems\nthe viscous-like drag force is due to the broken symmetry of the local contact\ngeometry.",
        "positive": "Collapse transition of flexible homopolymers with adhesive contacts: The presence of ordered structures such as helices in collapsed states of\npolymer chains is still an open question challenging physics and biology. In\nthis work, we present a potential model for polymer chains with monomers that\nare not strictly attractive, but that can make adhesive contacts with other\nmonomers. We find that the chain develop helical order during the process of\ncollapsing from an initially stretched conformation. It seems in this case that\nthe adhesive contacts help the polymer chain to stay trapped in the helix\nstate."
    },
    {
        "anchor": "Molecular conformations of dumbbell-shaped polymers in good solvent: We study conformational properties of diluted dumbbell polymers which consist\nof two rings that are attached to both ends of a linear spacer segment by using\nanalytical methods of field theory and bead-spring coarse-grained molecular\ndynamics simulations. We investigate the influence of the relative length of\nthe spacer segment to the length of side rings on the shape and the relative\nsize of dumbbells as compared to linear polymers of equal mass. We find that\ndumbbells with short spacers are much more compact than linear polymers.\nOppositely, we observe that the influence of side rings on the size of\ndumbbells becomes negligible with increasing length of a spacer. Consequently\ndumbbell molecules with long spacers become comparable in size with\ncorresponding linear chains. Our analytical theory predicts quantitative\ncross-over between short- and long-spacer behavior and is confirmed by\nnumerical simulations.",
        "positive": "Emergent vortices and phase separation in systems of chiral active\n  particles with dipolar interactions: Using Brownian dynamics (BD) simulations we investigate the self-organization\nof a monolayer of chiral active particles with dipolar interactions. Each\nparticle is driven by both, translational and rotational self-propulsion, and\ncarries a permanent point dipole moment at its center. The direction of the\ntranslational propulsion for each particle is chosen to be parallel to its\ndipole moment. Simulations are performed at high dipolar coupling strength and\na density below that related to motility-induced phase separation in simple\nactive Brownian particles. Despite this restriction, we observe a wealth of\nphenomena including formation of two types of vortices, phase separation, and\nflocking transitions. To understand the appearance and disappearance of\nvortices in the many-particle system, we further investigate the dynamics of\nsimple ring structures under the impact of self-propulsion."
    },
    {
        "anchor": "Nonlinear Fluid Dynamics Description of non-Newtonian Fluids: Nonlinear hydrodynamic equations for visco-elastic media are discussed. We\nstart from the recently derived fully hydrodynamic nonlinear description of\npermanent elasticity that utilizes the (Eulerian) strain tensor. The reversible\nquadratic nonlinearities in the strain tensor dynamics are of the 'lower\nconvected' type, unambiguously. Replacing the (often neglected) strain\ndiffusion by a relaxation of the strain as a minimal ingredient, a generalized\nhydrodynamic description of viscoelasticity is obtained. This can be used to\nget a nonlinear dynamic equation for the stress tensor (sometimes called\nconstitutive equation) in terms of a power series in the variables. The form of\nthis equation and in particular the form of the nonlinear convective term is\nnot universal but depends on various material parameters. A comparison with\nexisting phenomenological models is given. In particular we discuss how these\nad-hoc models fit into the hydrodynamic description and where the various\nnon-Newtonian contributions are coming from.",
        "positive": "Surface viscosity in simple liquids: The response of Newtonian liquids to small perturbations is usually\nconsidered to be fully described by homogeneous transport coefficients like\nshear and dilatational viscosity. However, the presence of strong density\ngradients at the liquid/vapor boundary of fluids hints at the possible\nexistence of an inhomogeneous viscosity. Here, we show that a surface viscosity\nemerges from the collective dynamics of interfacial layers in molecular\nsimulations of simple liquids. We estimate the surface viscosity to be 8-16\ntimes smaller than that of the bulk fluid at the thermodynamic point\nconsidered. This result can have important implications for reactions at liquid\nsurfaces in atmospheric chemistry and catalysis."
    },
    {
        "anchor": "How hidden 3D structure within crack fronts reveals energy balance: Griffith's energetic criterion, or `energy balance', has for a century formed\nthe basis for fracture mechanics; the energy flowing into a crack front is\nprecisely balanced by the dissipation (fracture energy) at the front. If the\ncrack front structure is not properly accounted for, energy balance will either\nappear to fail or lead to unrealistic results. Here, we study the influence of\nthe secondary structure of low-speed crack propagation in hydrogels under\ntensile loading conditions. We first show that these cracks are bistable;\neither simple (cracks having no secondary structure) or faceted crack states\n(formed by steps propagating along crack fronts) can be generated under\nidentical loading conditions. The selection of either crack state is determined\nby the form of the initial `seed' crack; perfect seed cracks generate simple\ncracks while a small local mode~III component generates crack fronts having\nmultiple steps. Step coarsening eventually leads to single steps that propagate\nalong crack fronts. As they evolve, steps locally change the instantaneous\nstructure and motion of the crack front, breaking transverse translational\ninvariance. In contrast to simple cracks, faceted cracks can, therefore, no\nlonger be considered as existing in a quasi-2D system. For both simple and\nfaceted cracks we simultaneously measure the energy flux and local dissipation\nalong these crack fronts over velocities, $v$, spanning $0<v<0.2c_R$ ($c_R$ is\nthe Rayleigh wave speed). We find that, in the presence of secondary structure\nwithin the crack front, the implementation of energy balance must be\ngeneralized for 3D systems; faceted cracks reveal energy balance, only when we\naccount for the local dynamic dissipation at each point along the crack front.",
        "positive": "Effective temperature of active matter: We follow the dynamics of an ensemble of interacting self-propelled motorized\nparticles in contact with an equilibrated thermal bath. We find that the\nfluctuation-dissipation relation allows for the definition of an effective\ntemperature that is compatible with the results obtained using a tracer\nparticle as a thermometer. The effective temperature takes a value which is\nhigher than the temperature of the bath and it is continuously controlled by\nthe motor intensity."
    },
    {
        "anchor": "Anomalous Vapor and Ice Nucleation in Water at Negative Pressures: A\n  Classical Density Functional Theory Study: In contrast to the abundance of work on the anomalous behavior of water, the\nrelationship between the water's thermodynamic anomalies and kinetics of phase\ntransition from metastable water is relatively unexplored. In this work, we\nhave employed classical density functional theory to provide a unified and\ncoherent picture of nucleation (both vapor and ice) from metastable water,\nespecially at negative pressure conditions. Our results suggest a peculiar\nnon-monotonic temperature dependence of liquid-vapor surface tension at\ntemperatures where liquid-vapor coexistence is metastable with respect to the\nice phase. The vapor nucleation barrier on isochoric cooling also shows a\nnon-monotonic temperature dependence. We further note that, for lower density\nisochores, the temperature of minimum vapor nucleation barrier ($T_{\\Delta\n\\Omega_{\\rm v/min}^*}$) does not coincide with the temperature of maximum\ndensity (TMD) where metastability is maximum. The temperature difference\nbetween the $T_{\\Delta \\Omega_{\\rm v/min}^*}$ and the TMD, however, decreases\nwith increasing the density of the isochore, suggesting a strong correlation\nbetween the propensity of cavitation and metastability of the liquid water at\nhigh densities. The vapor nucleation barrier along isobaric cooling shows an\ninteresting crossover behavior where it first increases on lowering the\ntemperature and then shows a non-monotonic behavior in the vicinity of the\nWidom line on further lowering the temperature. Our results on the ice\nnucleation from metastable water show an anomalous retracing behavior of the\nice nucleation barrier along isotherms and theoretically validate the recent\nfindings that the reentrant ice(Ih)-liquid coexistence can induce a drastic\nchange in the kinetics of ice nucleation. In addition, this study also provides\ndeeper insights into the origin of the isothermal compressibility maximum on\nisochoric cooling.",
        "positive": "The Role of Contact Angle Hysteresis for Fluid Transport in Wet Granular\n  Matter: The stability of sand castles is determined by the structure of wet\ngranulates. Experimental data about the size distribution of fluid pockets are\nambiguous about their origin. We discovered that contact angle hysteresis plays\na fundamental role in the equilibrium distribution of bridge volumes, and not\ngeometrical disorder as commonly conjectured, which has substantial\nconsequences on the mechanical properties of wet granular beds, including a\nhistory dependent rheology and lowered strength. Our findings are obtained\nusing a novel model where the Laplace pressures, bridge volumes and contact\nangles are dynamical variables associated to the contact points. While\naccounting for contact line pinning, we track the temporal evolution of each\nbridge. We observe a cross-over to a power-law decay of the variance of\ncapillary pressures at late times and a saturation of the variance of bridge\nvolumes to a finite value connected to contact line pinning. Large scale\nsimulations of liquid transport in the bridge network reveal that the\nequilibration dynamics at early times is well described by a mean field model.\nThe spread of final bridge volumes can be directly related to the magnitude of\ncontact angle hysteresis."
    },
    {
        "anchor": "Long-standing heterogeneity in shear-thickening suspension subjected to\n  swirling excitation: The heterogeneity in shear thickened state has recently gained attention. In\nthis study, we present a novel dynamic phenomenon in a dense suspension with a\nfree surface subjected to swirling excitation. When the volume fraction $\\Phi$\nand the oscillation frequency $f$ are beyond a critical threshold, numerous\npersistent jammed clusters emerge in the high-$\\phi$ region of the density\nwaves. A reduction in the thickness of the suspension shifts these critical\n$\\Phi$ and $f$ to lower values. The jammed cluster drives the downstream\nsuspension to accelerate forward, creating a steep density gradient upstream, a\nnotable difference from the previously reported motion associated with density\nwaves. Our results shed light on the evolution of heterogeneity, primarily\ngoverned by the interplay between kinematic instability and particle migrations\nunder free surface conditions. The negative slope of the constitutive curve is\nnot necessary for instability in this context. Furthermore, when the suspension\nis constrained by rigid confinement, no high-density regions persist beyond one\nperiod.",
        "positive": "Suspensions of magnetic nanogels at zero field: equilibrium structural\n  properties: Magnetic nanogels represent a cutting edge of magnetic soft matter research\ndue to their numerous potential applications. Here, using Langevin dynamics\nsimulations, we analyse the influence of magnetic nanogel concentration and\nembedded magnetic particle interactions on the self-assembly of magnetic\nnanogels at zero field. For this, we calculated radial distribution functions\nand structure factors for nanogels and magnetic particles within them. We found\nthat, in comparison to suspensions of free magnetic nanoparticles, where the\nself-assembly is already observed if the interparticle interaction strength\nexceeds the thermal fluctuations by approximately a factor of three,\nself-assembly of magnetic nanogels only takes place by increasing such ratio\nabove six. This magnetic nanogel self-assembly is realised by means of\nfavourable close contacts between magnetic nanoparticles from different\nnanogels. It turns out that for high values of interparticle interactions,\ncorresponding to the formation of internal rings in isolated nanogels, in their\nsuspensions larger magnetic particle clusters with lower elastic penalty can be\nformed by involving different nanogels. Finally, we show that when the\nself-assembly of these nanogels takes place, it has a drastic effect on the\nstructural properties even if the volume fraction of magnetic nanoparticles is\nlow."
    },
    {
        "anchor": "Mechanical properties of drying plant roots: Evolution of the\n  longitudinal Young's modulus of chick-pea roots with dessication: Mechanical characterizations of plant roots are of primary importance in\ngeophysics and engineering science for implementing mechanical models for the\nstability of root reinforced-soils, as well as in agronomy and soil science for\nunderstanding the penetration of roots in soils and optimizing crop. Yet the\nmechanical properties of plant roots depend on their water content, which can\ndrastically evolve with drying or flooding of the external soil. The present\nwork deals with the determination of the longitudinal Young's modulus of single\nnon-lignified plant roots, chick-peas (Cicer arietinum L.), tested in\ncompression along their root axis for different external environments: in\ncontrolled conditions of natural drying in air or in a osmotic solution of\nmannitol at the isotonic concentration where no water exchange occurs between\nthe root and the external solution. We submitted the chick-pea radicles to\nsuccessive mechanical compression cycles separated by rest periods to follow\nthe time evolution of the root mechanical properties in drying and non-drying\nenvironments. Control experiments on non-drying roots placed in isotonic\nosmotic solutions showed no evolution of the root's Young's modulus whose value\nwas around 2 MPa. On the contrary, the experiments performed in air exhibited a\ndramatic increase of the root's Young's modulus with the drying time, sometimes\nby a factor of 35. Moreover, the Young's modulus in these cases was observed to\nscale as a decaying power-law with the root's cross section measured at\ndiffrent times of drying. We interpreted our results in the framework of the\nmechanics of cellular foams.",
        "positive": "A model for the force stretching double-stranded chain molecules: We modify and extend the recently developed statistical mechanical model for\npredicting the thermodynamic properties of chain molecules having noncovalent\ndouble-stranded conformations, as in RNA or ssDNA, and $\\beta-$sheets in\nprotein, by including the constant force stretching at one end of molecules as\nin a typical single-molecule experiment. The conformations of double-stranded\nregions of the chain are calculated based on polymer graph-theoretic approach\n[S-J. Chen and K. A. Dill, J. Chem. Phys. {\\bf109}, 4602(1998)], while the\nunpaired single-stranded regions are treated as self-avoiding walks. Sequence\ndependence and excluded volume interaction are taken into account explicitly.\nTwo classes of conformations, hairpin and RNA secondary structure are explored.\nFor the hairpin conformations, all possible end-to-end distances corresponding\nto the different types of double-stranded regions are enumerated exactly. For\nthe RNA secondary structure conformations, a new recursive formula\nincorporating the secondary structure and end-to-end distribution has been\nderived. Using the model, we investigate the extension-force curves, contact\nand population distributions and re-entering phenomena, respectively. we find\nthat the force stretching homogeneous chains of hairpin and secondary structure\nconformations are very different: the unfolding of hairpins is two-state, while\nunfolding the latter is one-state. In addition, re-entering transitions only\npresent in hairpin conformations, but are not observed in secondary structure\nconformations."
    },
    {
        "anchor": "Free Energy Formalism for Particle Adsorption: The equilibrium properties of particles adsorption is investigated\ntheoretically. The model relies on a free energy formulation which allows to\ngeneralize the Maxwell-Boltzmann description to solutions for which the bulk\nvolume fraction of potentially adsorbed particles is very high. As an\napplication we consider the equilibrium physical adsorption of neutral and\ncharged particles from solution onto two parallel adsorbing surfaces.",
        "positive": "Dynamic path dependence of phase behaviors in dense active system: There are rich emergent phase behaviors in non-equilibrium active systems.\nFlocking and clustering are two representative dynamic phases. The relationship\nbetween these two phases is still unclear. In the paper, we numerically\ninvestigate the evolution of flocking and clustering in a system consisting of\nself-propelled particles with active reorientation. We consider the interplay\nbetween flocking and clustering phases under different initial states, and\nobserve an unstable domain in order parameters phase diagrams due to initial\nstates even in the absence of an explicit attraction. This point is different\nfrom the previous finding that active angular fluctuations lead to an earlier\nbreakdown of collective motion and the emergence of a new bi-stable regime in\nthe aligned active particles [R.Grossmann et al, New J. Phys.073033,14 (2012)].\nIn particular, we find that the existence of bi-stable states is due to the\ndiversity of dynamic paths arising from different initial states. By increasing\n(decreasing) the initial degree of ordering, the bi-stable state can be shifted\nto a more ordered flocking (disordered clustering) state. These results\nenlighten us pave the way to manipulate emergent behaviors and collective\nmotions of active system."
    },
    {
        "anchor": "Protein Adsorption on Lipid Monolayers at their Coexistence Region: We investigate theoretically the behavior of proteins as well as other large\nmacromolecules which are incorporated into amphiphilic monolayers at the\nair-water interface. We assume the monolayer to be in the coexistence region of\nthe ``main'' transition, where domains of the liquid condensed phase coexist\nwith the liquid expanded background. Using a simple mean-field free energy\naccounting for the interactions between proteins and amphiphilic molecules, we\nobtain the spatial protein distribution with the following characteristics.\nWhen the proteins preferentially interact with either the liquid condensed or\nliquid expanded domains, they will be dissolved in the respective phase. When\nthe proteins are energetically rather indifferent to the density of the\namphiphiles, they will be localized at the line boundary between the\n(two-dimensional) liquid expanded and condensed phases. In between these two\nlimiting cases, a delocalization transition of the proteins takes place. This\ntransition is accessible by changing the temperature or the amount of\nincorporated protein. These findings are in agreement with recent fluorescence\nmicroscopy experiments. Our results also apply to lipid multicomponent\nmembranes showing coexistence of distinct fluid phases.",
        "positive": "Texture transitions in binary mixtures of 6OBAC with compounds of its\n  homologous series: Recently we have observed in compounds of the 4,n-alkyloxybenzoic acid\nseries, with the homologous index n ranging from 6 to 9, a texture transition\nin the nematic range which subdivides the nematic phase in two sub-phases\ndisplaying different textures in polarised light analysis. To investigate a\npersistence of texture transitions in nematic phases, we prepared binary\nmixtures of 4,6-alkyloxybenzoic acid (6OBAC) with other members (7-,8-,9-,12-,\n16OBAC) of its homologous series. Binary mixtures exhibit a broadening in the\ntemperature ranges of both smectic and nematic phases. A nematic temperature\nrange of 75 C is observed. In the nematic phase, in spite of the microscopic\ndisorder introduced by mixing two components, the polarised light optics\nanalysis of the liquid crystal cells reveals a texture transition. In the case\nof the binary mixture of 6OBAC with 12OBAC and with 16OBAC, that is of\ncompounds with monomers of rather different lengths, the texture transition\ntemperature is not homogeneous in the cell, probably due to a local variation\nin the relative concentrations of compounds."
    },
    {
        "anchor": "Microscopic structure of liquid hydrogen: a neutron diffraction\n  experiment: We have measured the center-of-mass structure factor S(k) of liquid\npara-hydrogen by neutron diffraction, using the D4C diffractometer at the\nInstitute Laue Langevin, Grenoble, France. The present determination is at\nvariance with previous results obtained from inelastic neutron scattering data,\nbut agrees with path integral Monte Carlo simulations.",
        "positive": "Inverse flexoelectret effect: bending dielectrics by a uniform electric\n  field: It is highly desirable to discover an electromechanical coupling that allows\na dielectric material to generate curvature in response to a uniform electric\nfield, which would add a new degree of freedom for designing actuators.\nFlexoelectricity, a two-way coupling between polarization and strain gradient,\nis a good candidate. But its applications are usually limited to the nanoscale\ndue to its inherent size dependence. Here, an inverse flexoelectret effect in\nsilicone elastomers is introduced to overcome this limitation. Based on this\nidea, a flexing actuator which can generate large curvature at the millimeter\nlength scale is fabricated and shown to have excellent actuation performance\ncomparable with current nanoscale flexoelectric actuators. Theoretical analysis\nindicates that the new phenomenon originates from the interplay of electrets\nand Maxwell stress. This work opens an avenue for applying macroscopic\nflexoelectricity in actuators and flexible electronics."
    },
    {
        "anchor": "Wave Propagation in Periodic Plasma Media: A Semiclassical Approach: The propagation of electromagnetic waves in unmagnetized periodic plasma\nmedia is studied using the semiclassical wave packet approximation. The\nformalism gives rise to Berry effect terms in the equation of motion. The Berry\neffect manifests itself as Rytov polarization rotation law and the\npolarization-dependent Hall effect. The formalism is also applied to the case\nof non-periodic inhomogeneous plasma media.",
        "positive": "Adaptable materials via retraining: Elastic metamaterials are often designed for a single permanent function. We\nexplore the possibility of altering a material's function repeatedly through a\nself-organization, \"training\" process, controlled by applied strains. We show\nthat the elastic function can be altered numerous times, though each new\ntrained task imprints a memory. This ultimately leads to material degradation\nthrough the gradual reduction of the frequency gap in the density of states. We\nalso show that retraining adapts previously trained low energy modes to a new\nfunction. As a result consecutive trained responses are realized similarly. We\nshow how retraining can be exploited to attain a response that would otherwise\nbe difficult."
    },
    {
        "anchor": "Orienting lipid-coated graphitic micro-particles in solution using AC\n  electric fields: A new theoretical dual-ellipsoid Laplace model for\n  electro-orientation: Graphitic micro-particles coated with thin layers in solution are\ntechnologically interesting as they can be manipulated with electric fields.\nModeling the electrical manipulation of submerged layered micro-particles\nanalytically or numerically is not straight forward. In particular, the\ngeneration of reliable quantitative torque predictions for electro-orientation\nexperiments has been elusive. The traditional Laplace model approximates the\ncoated particle by an ellipsoid with a confocal ellipsoidal layer and solves\nLaplace's equation to produce convenient analytical predictions. However, due\nto the non-uniformity of the layer thickness around the ellipsoid, this method\ncan lead to incorrect torque predictions. Here we present a new theoretical\ndual-ellipsoid Laplace model that corrects the effect of the non-uniform layer\nthickness by calculating two layered ellipsoids, each accounting for the\ncorrect layer thickness along each relevant direction for the torque. Our model\ndescribes the electro-orientation of submerged lipid-coated graphitic\nmicro-particles in the presence of an alternating current (AC) electric field\nand is valid for ellipsoids with moderate aspect ratios and coated with thin\nshells. It is one of the first models to generate correct quantitative electric\ntorque predictions. We present model results for the torque versus frequency\nand compare them to our measurements for lipid-coated highly ordered pyrolytic\ngraphite (HOPG) micro-flakes in aqueous NaCl solution at MHz frequencies. The\nresults show how the lipid shell changes the overall electrical properties of\nthe micro-flakes so that the torque is low at low frequencies and increases at\nhigher frequencies into the MHz regime. The torque depends critically on the\nlipid-shell thickness, the solution conductivity and the shape of the particle,\nall of which can be used as handles to control the response of the particles.",
        "positive": "Pronounced structural crossover in supercritical water: There have been ample studies of the many phases of H2O in both its solid and\nlow pressure liquid states, and the transitions between them. Using molecular\ndynamics simulations we address the hitherto unexplored deeply supercritical\npressures, where no qualitative transitions are thought to take place and where\nall properties are expected to vary smoothly. On the basis of these simulations\nwe predict that water at supercritical pressures undergoes a structural\ncrossover across the Frenkel line at pressures as high as 45 times the critical\npressure. This provides a new insight into the water phase diagram and\nestablishes a link between the structural and dynamical properties of\nsupercritical water. Specifically, the crossover is demonstrated by a sharp and\npronounced at low pressures, and smooth at high pressures, signified by changes\nin the pair distribution functions and local coordination which coincide with\nthe dynamical transition (the loss of all oscillatory molecular motion) at the\nFrenkel line on the phase diagram."
    },
    {
        "anchor": "Surface-triggered cascade reactions between DNA linkers direct\n  self-assembly of colloidal crystals of controllable thickness: Functionalizing colloids with reactive DNA linkers is a versatile way of\nprogramming self-assembly. DNA selectivity provides direct control over\ncolloid-colloid interactions allowing the engineering of structures such as\ncomplex crystals or gels. However, self-assembly of localized and finite\nstructures remains an open problem with many potential applications. In this\nwork, we present a system in which functionalized surfaces initiate a cascade\nreaction between linkers leading to self-assembly of crystals with a\ncontrollable number of layers. Specifically, we consider colloidal particles\nfunctionalized by two families of complementary DNA linkers with mobile\nanchoring points, as found in experiments using emulsions or lipid bilayers. In\nbulk, intra-particle linkages formed by pairs of complementary linkers prevent\nthe formation of inter-particle bridges and therefore colloid-colloid\naggregation. However, colloids interact strongly with the surface given that\nthe latter can destabilize intra-particle linkages. When in direct contact with\nthe surface, colloids are activated, meaning that they feature more unpaired\nDNA linkers ready to react. Activated colloids can then capture and activate\nother colloids from the bulk through the formation of inter-particle linkages.\nUsing simulations and theory, validated by existing experiments, we clarify the\nthermodynamics of the activation and binding process and explain how\nparticle-particle interactions, within the adsorbed phase, weaken as a function\nof the distance from the surface. The latter observation underlies the\npossibility of self-assembling finite aggregates with controllable thickness\nand flat solid-gas interfaces. Our design suggests a new avenue to fabricate\nheterogeneous and finite structures.",
        "positive": "Controlling the fluid-fluid mixing-demixing phase transition with\n  electric fields: We review recent theoretical advances on controlling the fluid-fluid phase\ntransition with electric fields. Using a mean-field approach, we compare the\neffects of uniform versus non-uniform electric fields, and show how non-uniform\nfields are better at altering the phase diagram. Focusing on non-uniform\nfields, we then discuss the behavior of the fluid concentration profile and the\nparameters (temperature, fluid concentration, etc.) that control the location\nof the fluid-fluid interface from both equilibrium and dynamic perspectives."
    },
    {
        "anchor": "Ground State and Quasiparticle Spectrum of a Two Component Bose-Einstein\n  Condensate: We consider a dilute atomic Bose-Einstein condensate with two non-degenerate\ninternal energy levels. The presence of an external radiation field can result\nin new ground states for the condensate which result from the lowering of the\ncondensate energy due to the interaction energy with the field. In this\napproach there are no instabilities in the quasiparticle spectrum as was\npreviously found by Goldstein and Meystre (Phys. Rev. A \\QTR{bf}{55}, 2935\n(1997)).",
        "positive": "Aging in a mean field elastoplastic model of amorphous solids: We construct a mean-field elastoplastic description of the dynamics of\namorphous solids under arbitrary time-dependent perturbations, building on the\nwork of Lin and Wyart [Phys. Rev. X 6, 011005 (2016)] for steady shear. Local\nstresses are driven by power-law distributed mechanical noise from yield events\nthroughout the material, in contrast to the well-studied H\\'{e}braud-Lequeux\nmodel where the noise is Gaussian. We first use a mapping to a mean first\npassage time problem to study the phase diagram in the absence of shear, which\nshows a transition between an arrested and a fluid state. We then introduce a\nboundary layer scaling technique for low yield rate regimes, which we first\napply to study the scaling of the steady state yield rate on approaching the\narrest transition. These scalings are further developed to study the aging\nbehaviour in the glassy regime, for different values of the exponent $\\mu$\ncharacterizing the mechanical noise spectrum. We find that the yield rate\ndecays as a power-law for $1<\\mu<2$, a stretched exponential for $\\mu=1$ and an\nexponential for $\\mu<1$, reflecting the relative importance of far-field and\nnear-field events as the range of the stress propagator is varied. Comparison\nof the mean-field predictions with aging simulations of a lattice elastoplastic\nmodel shows excellent quantitative agreement, up to a simple rescaling of time."
    },
    {
        "anchor": "Annealing cycles and the self-organization of functionalized colloids: The self-assembly of functionalized (patchy) particles with directional\ninteractions into target structures is still a challenge, despite the\nsignificant experimental advances on their synthesis. The self-assembly\npathways are typically characterized by high energy barriers that hinder the\naccess to stable (equilibrium) structures. A possible strategy to tackle this\nchallenge is to perform annealing cycles. By periodically switching on and off\nthe inter-particle bonds, one expects to smooth-out the kinetic pathways and\nfavor the assembly of targeted structures. Preliminary results have shown that\nthe efficiency of annealing cycles depends strongly on their frequency. Here,\nwe study numerically how this frequency-dependence scales with the strength of\nthe directional interactions (size of the patch $\\sigma$). We use analytical\narguments to show that the scaling results from the statistics of a random walk\nin configurational space.",
        "positive": "Self-assembling multiblock amphiphiles: Molecular design, supramolecular\n  structure, and mechanical properties: We perform off-lattice, canonical ensemble molecular dynamics simulations of\nthe self-assembly of long segmented copolymers consisting of alternating,\ntunably attractive and hydrophobic {\\em binder} domains, connected by\nhydrophilic {\\em linker} chains whose length may be separately controlled. In\nsuch systems, the molecular design of the molecule directly determines the\nbalance between energetic and entropic tendencies. We determine the structural\nphase diagram of this system, which shows collapsed states (dominated by the\nattractive linkers' energies), swollen states (dominated by the random coil\nlinkers' entropies) as well as intermediate network hydrogel phases, where the\nlong molecules exhibit partial collapse to a {\\em single molecule network}\nstate. We present an analysis of the connectivity and spatial structure of this\nnetwork phase, and relate its basic topology to mechanical properties, using a\nmodified rubber elasticity model. The mechanical properties are further\ncharacterized in a direct computational implementation of oscillatory rheology\nmeasurements. We find that it is possible to optimize the mechanical\nperformance by an appropriate choice of molecular design, which may point the\nway to novel synthetics that make optimal mechanical use of constituent\npolymers."
    },
    {
        "anchor": "The Magnus (Kutta-Jukovskii) Force Acting on a Sphere: The expression is derived for the Magnus force acting on the sphere.",
        "positive": "Energetically favoured defects in dense packings of particles on\n  spherical surfaces: The dense packing of interacting particles on spheres has proved to be a\nuseful model for virus capsids and colloidosomes. Indeed, icosahedral symmetry\nobserved in virus capsids corresponds to potential energy minima that occur for\nmagic numbers of, e.g., 12, 32 and 72 identical Lennard-Jones particles, for\nwhich the packing has exactly the minimum number of twelve five-fold defects.\nIt is unclear, however, how stable these structures are against thermal\nagitation. We investigate this property by means of basin-hopping global\noptimisation and Langevin dynamics for particle numbers between ten and one\nhundred. An important measure is the number and type of point defects, that is,\nparticles that do not have six nearest neighbours. We find that small\nicosahedral structures are the most robust against thermal fluctuations,\nexhibiting fewer excess defects and rearrangements for a wide temperature\nrange. Furthermore, we provide evidence that excess defects appearing at low\nnon-zero temperatures lower the potential energy at the expense of entropy. At\nhigher temperatures defects are, as expected, thermally excited and thus\nentropically stabilised. If we replace the Lennard-Jones potential by a very\nshort-ranged (Morse) potential, which is arguably more appropriate for colloids\nand virus capsid proteins, we find that the same particle numbers give a\nminimum in the potential energy, although for larger particle numbers these\nminima correspond to different packings. Furthermore, defects are more\ndifficult to excite thermally for the short-ranged potential, suggesting that\nthe short-ranged interaction further stabilises equilibrium structures."
    },
    {
        "anchor": "Self-Assembly of Spiral Patterns in Confined System with Competing\n  Interactions: Colloidal particles in polymer solutions and functionalized nanoparticles\noften exhibit short-range attraction coupled with long-range repulsion (SALR)\nleading to the spontaneous formation of symmetric patterns. Chiral\nnanostructures formed by thin film of SALR particles have not been reported\nyet. In this study, we observe striking topological transitions from a\nsymmetric pattern of concentric rings to a chiral structure of a spiral shape,\nwhen the system is in hexagonal confinement. We find that the spiral formation\ncan be induced either by breaking the system symmetry with a wedge, or by\nmelting of the rings. In the former case, the chirality of the spiral is\ndetermined by orientation of the wedge and thus can be controlled. In the\nlatter, the spiral rises due to thermally induced defects and is absent in the\naverage particle distribution that form highly regular hexagonal patterns in\nthe central part of the system. These hexagonal patterns can be explained by\ninterference of planar density waves. Thermodynamic considerations indicate\nthat equilibrium spirals can appear spontaneously in any stripe-forming system\nconfined in a hexagon with a small wedge, provided that certain conditions are\nsatisfied by a set of phenomenological parameters.",
        "positive": "Thermodynamic relations for DNA phase transitions: The force induced unzipping transition of a double stranded DNA is considered\nfrom a purely thermodynamic point of view. This analysis provides us with a set\nof relations that can be used to test microscopic theories and experiments. The\nthermodynamic approach is based on the hypothesis of impenetrability of the\nforce in the zipped state. The melting and the unzipping transitions are\nconsidered in the same framework and compared with the existing statistical\nmodel results. The analysis is then extended to a possible continuous unzipping\ntransition."
    },
    {
        "anchor": "Chaos driven by interfering memory: The transmission of information can couple two entities of very different\nnature, one of them serving as a memory for the other. Here we study the\nsituation in which information is stored in a wave field and serves as a memory\nthat pilots the dynamics of a particle. Such a system can be implemented by a\nbouncing drop generating surface waves sustained by a parametric forcing. The\nmotion of the resulting \"walker\" when confined in a harmonic potential well is\ngenerally disordered. Here we show that these trajectories correspond to\nchaotic regimes characterized by intermittent transitions between a discrete\nset of states. At any given time, the system is in one of these states\ncharacterized by a double quantization of size and angular momentum. A low\ndimensional intermittency determines their respective probabilities. They thus\nform an eigenstate basis of decomposition for what would be observed as a\nsuperposition of states if all measurements were intrusive.",
        "positive": "Effect of substrate heterogeneity and topology on epithelial tissue\n  growth dynamics: Tissue growth kinetics and interface dynamics depend on the properties of the\ntissue environment and cell-cell interactions. In cellular environments,\nsubstrate heterogeneity and geometry arise from a variety factors, such as the\nstructure of the extracellular matrix and nutrient concentration. We used the\nCellSim3D model, a kinetic division simulator, to investigate the growth\nkinetics and interface roughness dynamics of epithelial tissue growth on\nheterogeneous substrates with varying topologies. The results show that the\npresence of quenched disorder has a clear effect on the colony morphology and\nthe roughness scaling of the interface in the moving interface regime. In a\nmedium with quenched disorder, the tissue interface has a smaller interface\nroughness exponent, $\\alpha$, and a larger growth exponent, $\\beta$. The\nscaling exponents also depend on the topology of the substrate and cannot be\ncategorized by well-known universality classes."
    },
    {
        "anchor": "Motion of a Viscoelastic Micellar Fluid Around a Cylinder: Flow and\n  Fracture: We present an experimental study of the motion of a viscoelastic micellar\nmaterial around a moving cylinder, which ranges in response from fluid-like\nflow to solid-like tearing and fracture, depending on the cylinder radius and\nvelocity. The observation of viscoelastic crack propagation driven by the\ncylinder indicates an extremely low tear strength, approximately equal to the\nsteady state surface tension of the fluid. At the highest speeds a driven crack\nis observed in front of the cylinder, propagating with a fluctuating speed\nequal on average to the cylinder speed, here as low as 5% of the elastic wave\nspeed in the medium.",
        "positive": "Current fluctuations in nanopores: the effects of electrostatic and\n  hydrodynamic interactions: Using nonequilibrium Langevin dynamics simulations of an electrolyte with\nexplicit solvent particles, we investigate the effect of hydrodynamic\ninteractions on the power spectrum of ionic nanopore currents. At low\nfrequency, we find a power-law dependence of the power spectral density, with\nan exponent depending on the ion density. Surprisingly, however, the exponent\nis not affected by the presence of the neutral solvent particles. We conclude\nthat hydrodynamic interactions do not affect the shape of the power spectrum in\nthe frequency range studied."
    },
    {
        "anchor": "Macroscopic DNA-programmed photonic crystals via seeded growth: Photonic crystals -- a class of materials whose optical properties derive\nfrom their structure in addition to their composition -- can be created by\nself-assembling particles whose sizes are comparable to the wavelengths of\nvisible light. Proof-of-principle studies have shown that DNA can be used to\nguide the self-assembly of micrometer-sized colloidal particles into fully\nprogrammable crystal structures with photonic properties in the visible\nspectrum. However, the extremely temperature-sensitive kinetics of\nmicrometer-sized DNA-functionalized particles has frustrated attempts to grow\nlarge, monodisperse crystals that are required for photonic metamaterial\napplications. Here we describe a robust two-step protocol for self-assembling\nsingle-domain crystals that contain millions of optical-scale\nDNA-functionalized particles: Monodisperse crystals are initially assembled in\nmonodisperse droplets made by microfluidics, after which they are grown to\nmacroscopic dimensions via seeded diffusion-limited growth. We demonstrate the\ngenerality of our approach by assembling different macroscopic single-domain\nphotonic crystals with metamaterial properties, like structural coloration,\nthat depend on the underlying crystal structure. By circumventing the\nfundamental kinetic traps intrinsic to crystallization of optical-scale\nDNA-coated colloids, we eliminate a key barrier to engineering photonic devices\nfrom DNA-programmed materials.",
        "positive": "Solvation of Nonionic Poly(Ethylene Oxide) Surfactant Brij 35 in Organic\n  and Aqueous-Organic Solvents: Hypothesis: By combining the experimental small- and wide-angle x-ray\nscattering (SWAXS) method with molecular dynamics simulations and the\ntheoretical 'complemented-system approach' it is possible to obtain detailed\ninformation about the intra- and inter-molecular structure and dynamics of the\nsolvation and hydration of the surfactant in organic and mixed solvents, e.g.,\nof the nonionic surfactant Brij 35 (C12E23) in alcohols and aqueous\nalcohol-rich ternary systems. This first application of the complemented-system\napproach to the surfactant system will promote the use of this powerful\nmethodology that is based on experimental and calculated SWAXS data in studies\nof colloidal systems. By applying high-performance computing systems, such an\napproach is readily available for studies in the colloidal domain.\n  Experiments: SWAXS experiments and MD simulations were performed for binary\nBrij 35/alcohol and ternary Brij 35/water/alcohol systems with ethanol,\nn-butanol and n-hexanol as the organic solvent component at 25 {\\deg}C.\n  Findings: We confirmed the presence of solvated Brij 35 monomers in the\nstudied organic media, revealed their preferential hydration and discussed\ntheir structural and dynamic features at the intra- and inter-molecular levels.\nAnisotropic effective surfactant molecular conformations were found. The\ninfluence of the hydrophobicity of the organic solvent on the hydration\nphenomena of surfactant molecules was explained."
    },
    {
        "anchor": "Effect of Noise on DNA Sequencing via Transverse Electronic Transport: Previous theoretical studies have shown that measuring the transverse current\nacross DNA strands while they translocate through a nanopore or channel may\nprovide a statistically distinguishable signature of the DNA bases, and may\nthus allow for rapid DNA sequencing. However, fluctuations of the environment,\nsuch as ionic and DNA motion, introduce important scattering processes that may\naffect the viability of this approach to sequencing. To understand this issue,\nwe have analyzed a simple model that captures the role of this complex\nenvironment in electronic dephasing and its ability to remove charge carriers\nfrom current-carrying states. We find that these effects do not strongly\ninfluence the current distributions due to the off-resonant nature of tunneling\nthrough the nucleotides - a result we expect to be a common feature of\ntransport in molecular junctions. In particular, only large scattering\nstrengths, as compared to the energetic gap between the molecular states and\nthe Fermi level, significantly alter the form of the current distributions.\nSince this gap itself is quite large, the current distributions remain\nprotected from this type of noise, further supporting the possibility of using\ntransverse electronic transport measurements for DNA sequencing.",
        "positive": "Clustering-induced attraction in granular mixtures of rods and spheres: Depletion-induced aggregation of rods enhanced by clustering is observed to\nproduce a novel model of attractive pairs of rods separated by a line of\nspheres in a quasi-2D, vertically-shaken, granular gas of rods and spheres. We\nshow that the stability of these peculiar granular aggregates increases as a\nfunction of shaking intensity. Velocity distributions of spheres inside and\noutside of a pair of rods trapping a line of spheres show a clear suppression\nof the momentum acquired by the trapped spheres. The condensed phase formed\nbetween the rods is caused by a clustering instability of the trapped spheres,\nenhanced by a vertical guidance produced by the confining rods. The liberated\narea corresponding to direct excluded-volume pairs and indirect\ndepletion-aggregated pairs is measured as a function of time. The stability of\nrod pairs mediated by spheres reveals an attraction comparable in strength to\nthe one purely induced by depletion forces."
    },
    {
        "anchor": "Acoustodynamic mass determination: Accounting for inertial effects in\n  acoustic levitation of granular materials: Acoustic traps use forces exerted by sound waves to confine and transport\nsmall objects. The dynamics of an object moving in the force landscape of an\nacoustic trap can be significantly influenced by the inertia of the surrounding\nfluid medium. These inertial effects can be observed by setting a trapped\nobject in oscillation and tracking it as it relaxes back to mechanical\nequilibrium in its trap. Large deviations from Stokesian dynamics during this\nprocess can be explained quantitatively by accounting for boundary-layer\neffects in the fluid. The measured oscillations of a perturbed particle then\ncan be used not only to calibrate the trap but also to characterize the\nparticle.",
        "positive": "Experimentally measuring rolling and sliding in three-dimensional dense\n  granular packings: We experimentally measure a three-dimensional (3D) granular system's\nreversibility under cyclic compression. We image the grains using a\nrefractive-index-matched fluid, then analyze the images using the artificial\nintelligence of variational autoencoders. These techniques allow us to track\nall the grains' translations and 3D rotations with accuracy sufficient to infer\nsliding and rolling displacements. Our observations reveal unique roles played\nby 3D rotational motions in granular flows. We find that rotations and\ncontact-point motion dominate the dynamics in the bulk, far from the\nperturbation's source. Furthermore, we determine that 3D rotations are\nirreversible under cyclic compression. Consequently, contact-point sliding,\nwhich is dissipative, accumulates throughout the cycle. Using numerical\nsimulations whose accuracy our experiment supports, we discover that much of\nthe dissipation occurs in the bulk, where grains rotate more than they\ntranslate. Our observations suggest that the analysis of 3D rotations is needed\nfor understanding granular materials' unique and powerful ability to absorb and\ndissipate energy."
    },
    {
        "anchor": "Kinetics of Surface Enrichment: A Molecular Dynamics Study: We use molecular dynamics (MD) to study the kinetics of surface enrichment\n(SE) in a stable homogeneous mixture (AB), placed in contact with a surface\nwhich preferentially attracts A. The SE profiles show a characteristic\ndouble-exponential behavior with two length scales: \\xi_-, which rapidly\nsaturates to its equilibrium value, and \\xi_+, which diverges as a power-law\nwith time (\\xi_+ \\sim t^\\theta). We find that hydrodynamic effects result in a\ncrossover of the growth exponent from \\theta \\simeq 0.5 to \\theta \\simeq 1.0.\nThere is also a corresponding crossover in the growth dynamics of the SE-layer\nthickness.",
        "positive": "Inherent Structure Energy is a Good Indicator of Molecular Mobility in\n  Glasses: Glasses produced via physical vapor deposition can display greater kinetic\nstability and lower enthalpy than glasses prepared by liquid cooling. While the\nreduced enthalpy has often been used as a measure of the stability, it is not\nobvious whether dynamic measures of stability provide the same view. Here, we\nstudy dynamics in vapor-deposited and liquid-cooled glass films using molecular\nsimulations of a bead-spring polymer model as well as a Lennard-Jones binary\nmixture in two and three dimensions. We confirm that the dynamics in\nvapor-deposited glasses is indeed slower than in ordinary glasses. We further\nshow that the inherent structure energy is a good reporter of local dynamics,\nand that aged systems and glasses prepared by cooling at progressively slower\nrates exhibit the same behavior as vapor-deposited materials when they both\nhave the same inherent structure energy. These findings suggest that the\nstability inferred from measurements of the energy is also manifested in\ndynamic observables, and they strengthen the view that vapor deposition\nprocesses provide an effective strategy for creation of stable glasses."
    },
    {
        "anchor": "A parallel algorithm for step- and chain-growth polymerization in\n  Molecular Dynamics: Classical Molecular Dynamics (MD) simulations provide insight on the\nproperties of many soft-matter systems. In some situations it is interesting to\nmodel the creation of chemical bonds, a process that is not part of the MD\nframework. In this context, we propose a parallel algorithm for step- and\nchain-growth polymerization that is based on a generic reaction scheme, works\nat a given intrinsic rate and produces continuous trajectories. We present an\nimplementation in the ESPResSo++ simulation software and compare it with the\ncorresponding feature in LAMMPS. For chain growth, our results are compared to\nthe existing simulation literature. For step growth, a rate equation is\nproposed for the evolution of the crosslinker population that compares well to\nthe simulations for low crosslinker functionality or for short times.",
        "positive": "Anomalous Thermomechanical Properties of a Self-propelled Colloidal\n  Fluid: We use numerical simulations to compute the equation of state of a suspension\nof spherical, self-propelled nanoparticles. We study in detail the effect of\nexcluded volume interactions and confinement as a function of the system\ntemperature, concentration and strength of the propulsion. We find a striking\nnon-monotonic dependence of the pressure with the temperature, and provide\nsimple scaling arguments to predict and explain the occurrence of such an\nanomalous behavior. We conclude the paper by explicitly showing how our results\nhave an important implications for the effective forces exerted by fluids of\nself-propelled particles on passive, larger components."
    },
    {
        "anchor": "Glass formation in a mixture of hard disks and hard ellipses: We present an event-driven molecular dynamics study of glass formation in\ntwo-dimensional binary mixtures composed of hard disks and hard ellipses, where\nboth types of particles have the same area. We demonstrate that characteristic\nglass-formation behavior appears upon compression under appropriate conditions\nin such systems. In particular, while a rotational glass transition occurs only\nfor the ellipses, both types of particles undergo a kinetic arrest in the\ntranslational degrees of freedom at a single density. The translational\ndynamics for the ellipses is found to be faster than that for the disks within\nthe same system, indicating that shape anisotropy promotes the translational\nmotion of particles. We further examine the influence of mixture's composition\nand aspect ratio on the glass formation. For the mixtures with an ellipse\naspect ratio of $k=2$, both translational and rotational glass transition\ndensities decrease with increasing the disk concentration at a similar rate and\nhence, the two glass transitions remain close to each other at all\nconcentrations investigated. By elevating $k$, however, the rotational glass\ntransition density diminishes at a faster rate than the translational one,\nleading to the formation of an orientational glass for the ellipses between the\ntwo transitions. Our simulations imply that mixtures of particles with\ndifferent shapes emerge as a promising model for probing the role of particle\nshape in determining the properties of glass-forming liquids. Furthermore, our\nwork illustrates the potential of using knowledge concerning the dependence of\nglass-formation properties on mixture's composition and particle shape to\nassist in the rational design of amorphous materials.",
        "positive": "Electric field unbinding of solid-supported lipid multilayers: We studied by X-ray reflectivity the behaviour of fully hydrated\nsolid-supported lipid multilayers under the influence of a transverse electric\nfield, under conditions routinely used in the electroformation process. The\nkinetics of sample loss (unbinding) was measured as a function of the amplitude\nand frequency of the applied field by monitoring the integrated intensity of\nthe Bragg peaks. We also performed a time-resolved analysis of the intensity of\nthe first Bragg peak and characterized the final state of the sample."
    },
    {
        "anchor": "Instabilities during the evaporation of a film: non glassy polymer +\n  volatile solvent: We consider solutions where the surface tension of the solvent is smaller\nthan the surface tension of the polymer. In an evaporating film, a plume of\nsolvent rich fluid, then induces a local depression in surface tension, and the\nsurface forces tend to strengthen the plume. We give an estimate (at the level\nof scaling laws) for the minimum thickness required to obtain this instability.\nWe predict that the thickness a) is a decreasing function of the solvent vapor\npressure b) should be very small (<1 micron) provided that the initial solution\nis rather dilute. The overall evaporation time for the film should be much\nlonger than the growth time of the instability. The instability should lead to\ndistortions of the free surface and may be optically observable. It should\ndominate over the classical Bernard-Marangoni instability induced by cooling.",
        "positive": "Coupled electro-elastic deformation and instabilities of a toroidal\n  membrane: We analyse here the problem of large deformation of dielectric elastomeric\nmembranes under coupled electromechanical loading. Extremely large deformations\n(enclosed volume changes of 100 times and greater) of a toroidal membrane are\nstudied by the use of a variational formulation that accounts for the total\nenergy due to mechanical and electrical fields. A modified shooting method is\nadopted to solve the resulting system of coupled and highly nonlinear ordinary\ndifferential equations. We demonstrate the occurrence of limit point,\nwrinkling, and symmetry-breaking buckling instabilities in the solution of this\nproblem. Onset of each of these \"reversible\" instabilities depends\nsignificantly on the ratio of the mechanical load to the electric load, thereby\nproviding a control mechanism for state switching."
    },
    {
        "anchor": "Memory in an aging molecular glass: The dielectric susceptibility of the molecular liquid sorbitol below its\ncalorimetric glass transition displays memory strikingly similar to that of a\nvariety of glassy materials. During a temporary stop in cooling, the\nsusceptibility changes with time, and upon reheating the susceptibility\nretraces these changes. To investigate the out-of-equilibrium state of the\nliquid as it displays this memory, the heating stage of this cycle is\ninterrupted and the subsequent aging characterized. At temperatures above that\nof the original cooling stop, the liquid enters a state on heating with an\neffective age that is proportional to the duration of the stop, while at lower\ntemperatures no effective age can be assigned and subtler behavior emerges.\nThese results, which reveal differences with memory displayed by spin glasses,\nare discussed in the context of the liquid's energy landscape.",
        "positive": "Corrections to Scaling in the Hydrodynamic Properties of Dilute Polymer\n  Solutions: We discuss the hydrodynamic radius $R_H$ of polymer chains in good solvent,\nand show that the leading order correction to the asymptotic law $R_H \\propto\nN^\\nu$ ($N$ degree of polymerization, $\\nu \\approx 0.59$) is an ``analytic''\nterm of order $N^{-(1 - \\nu)}$, which is directly related to the discretization\nof the chain into a finite number of beads. This result is further corroborated\nby exact calculations for Gaussian chains, and extensive numerical simulations\nof different models of good--solvent chains, where we find a value of $1.591\n\\pm 0.007$ for the asymptotic universal ratio $R_G / R_H$, $R_G$ being the\nchain's gyration radius. For $\\Theta$ chains the data apparently extrapolate to\n$R_G / R_H \\approx 1.44$, which is different from the Gaussian value 1.5045,\nbut in accordance with previous simulations. We also show that the\nexperimentally observed deviations of the initial decay rate in dynamic light\nscattering from the asymptotic Benmouna--Akcasu value can partly be understood\nby similar arguments."
    },
    {
        "anchor": "Molecular dynamics simulation: a tool for exploration and discovery\n  using simple models: Emergent phenomena share the fascinating property of not being obvious\nconsequences of the design of the system in which they appear. This\ncharacteristic is no less relevant when attempting to simulate such phenomena,\ngiven that the outcome is not always a foregone conclusion. The present survey\nfocuses on several simple model systems that exhibit surprisingly rich emergent\nbehavior, all studied by MD simulation. The examples are taken from the\ndisparate fields of fluid dynamics, granular matter and supramolecular\nself-assembly. In studies of fluids modeled at the detailed microscopic level\nusing discrete particles, the simulations demonstrate that complex hydrodynamic\nphenomena in rotating and convecting fluids, the Taylor-Couette and\nRayleigh-B\\'enard instabilities, can not only be observed within the limited\nlength and time scales accessible to MD, but even quantitative agreement can be\nachieved. Simulation of highly counterintuitive segregation phenomena in\ngranular mixtures, again using MD methods, but now augmented by forces\nproducing damping and friction, leads to results that resemble experimentally\nobserved axial and radial segregation in the case of a rotating cylinder, and\nto a novel form of horizontal segregation in a vertically vibrated layer.\nFinally, when modeling self-assembly processes analogous to the formation of\nthe polyhedral shells that package spherical viruses, simulation of suitably\nshaped particles reveals the ability to produce complete, error-free assembly,\nand leads to the important general observation that reversible growth steps\ncontribute to the high yield. While there are limitations to the MD approach,\nboth computational and conceptual, the results offer a tantalizing hint of the\nkinds of phenomena that can be explored, and what might be discovered when\nsufficient resources are brought to bear on a problem.",
        "positive": "Geometry and topology of knotted ring polymers in an array of obstacles: We study knotted polymers in equilibrium with an array of obstacles which\nmodels confinement in a gel or immersion in a melt. We find a crossover in both\nthe geometrical and the topological behavior of the polymer. When the polymers'\nradius of gyration, $R_G$, and that of the region containing the knot,\n$R_{G,k}$, are small compared to the distance b between the obstacles, the knot\nis weakly localised and $R_G$ scales as in a good solvent with an amplitude\nthat depends on knot type. In an intermediate regime where $R_G > b > R_{G,k}$,\nthe geometry of the polymer becomes branched. When $R_{G,k}$ exceeds b, the\nknot delocalises and becomes also branched. In this regime, $R_G$ is\nindependent of knot type. We discuss the implications of this behavior for gel\nelectrophoresis experiments on knotted DNA in weak fields."
    },
    {
        "anchor": "Measuring and upscaling micromechanical interactions in a cohesive\n  granular material: The mechanical properties of a disordered heterogeneous medium depend, in\ngeneral, on a complex interplay between multiple length scales. Connecting\nlocal interactions to macroscopic observables, such as stiffness or fracture,\nis thus challenging in this type of material. Here, we study the properties of\na cohesive granular material composed of glass beads held together by soft\npolymer bridges. We characterise the mechanical response of single bridges\nunder traction and shear, using a setup based on the deflection of flexible\nmicropipettes. These measurements, along with information from X-ray\nmicrotomograms of the granular packings, then inform large-scale discrete\nelement model (DEM) simulations. Although simple, these simulations are\nconstrained in every way by empirical measurement and accurately predict\nmechanical responses of the aggregates, including details on their compressive\nfailure, and how the material's stiffness depends on the stiffness and geometry\nof its parts. By demonstrating how to accurately relate microscopic information\nto macroscopic properties, these results provide new perspectives for\npredicting the behaviour of complex disordered materials, such as porous rock,\nsnow, or foam.",
        "positive": "Adam-Gibbs Model for the Supercooled Dynamics in OTP-OPP Mixture: Dielectric measurements of the alpha-relaxation time were carried out on a\nmixture of ortho-terphenyl (OTP) with ortho-phenylphenol (OPP), over a range of\ntemperatures at two pressures, 0.1 and 28.8 MPa. These are the same conditions\nfor which heat capacity, thermal expansivity, and compressibility measurements\nwere reported by Takahara et al. [S. Takahara, M. Ishikawa, O. Yamamuro, and T.\nMatsuo, Journal of Physical Chemistry B 103 (16), 3288 (1999).] for the same\nmixture. From the combined dynamic and thermodynamic data, we determine that\ndensity and temperature govern to an equivalent degree the variation of the\nrelaxation times with temperature. Over the measured range, the dependence of\nthe relaxation times on configurational entropy is in accord with the\nAdam-Gibbs model, and this dependence is invariant to pressure. Consistent with\nthe implied connection between relaxation and thermodynamic properties, the\nkinetic and thermodynamic fragilities are found to have the same pressure\nindependence. In comparing the relaxation properties of the mixture to those of\nneat OTP, density effects are stronger in the former, perhaps suggestive of\nless efficient packing."
    },
    {
        "anchor": "Nonlinear Screening and Effective Electrostatic Interactions in\n  Charge-Stabilized Colloidal Suspensions: A nonlinear response theory is developed and applied to electrostatic\ninteractions between spherical macroions, screened by surrounding microions, in\ncharge-stabilized colloidal suspensions. The theory describes leading-order\nnonlinear response of the microions (counterions, salt ions) to the\nelectrostatic potential of the macroions and predicts microion-induced\neffective many-body interactions between macroions. A linear response\napproximation [Phys. Rev. E 62, 3855 (2000)] yields an effective pair potential\nof screened-Coulomb (Yukawa) form, as well as a one-body volume energy, which\ncontributes to the free energy. Nonlinear response generates effective\nmany-body interactions and essential corrections to both the effective pair\npotential and the volume energy. By adopting a random-phase approximation (RPA)\nfor the response functions, and thus neglecting microion correlations,\npractical expressions are derived for the effective pair and triplet potentials\nand for the volume energy. Nonlinear screening is found to weaken repulsive\npair interactions, induce attractive triplet interactions, and modify the\nvolume energy. Numerical results for monovalent microions are in good agreement\nwith available ab initio simulation data and demonstrate that nonlinear effects\ngrow with increasing macroion charge and concentration and with decreasing salt\nconcentration. In the dilute limit of zero macroion concentration,\nleading-order nonlinear corrections vanish. Finally, it is shown that nonlinear\nresponse theory, when combined with the RPA, is formally equivalent to the\nmean-field Poisson-Boltzmann theory and that the linear response approximation\ncorresponds, within integral-equation theory, to a linearized hypernetted-chain\nclosure.",
        "positive": "Disentangling $1/f$ noise from confined ion dynamics: Ion transport through biological and solid-state nanochannels is known to be\na highly noisy process. The power spectrum of current fluctuations is\nempirically known to scale like the inverse of frequency, following the\nlong-standing yet poorly understood Hooge's law. Here, we report measurements\nof current fluctuations across nanometer-scale two-dimensional channels with\ndifferent surface properties. The structure of fluctuations is found to depend\non channel's material. While in pristine channels current fluctuations scale\nlike $1/f^{1+a}$ with $a = 0 - 0.5$, the noise power spectrum of activated\ngraphite channels displays different regimes depending on frequency. Based on\nthese observations, we develop a theoretical formalism directly linking ion\ndynamics and current fluctuations. We predict that the noise power spectrum\ntake the form $1/f \\times S_\\text{channel}(f)$, where $1/f$ fluctuations emerge\nin fluidic reservoirs on both sides of the channel and $S_\\text{channel}$\ndescribes fluctuations inside it. Deviations to Hooge's law thus allow direct\naccess to the ion transport dynamics of the channel -- explaining the entire\nphenomenology observed in experiments on 2D nanochannels. Our results\ndemonstrate how current fluctuations can be used to characterize nanoscale ion\ndynamics."
    },
    {
        "anchor": "Unveiling the Interstitial Pressure Between Growing Ice Crystals During\n  Ice-Templating Using a Lipid Lamellar Probe: What is pressure generated by ice crystals during ice-templating? This work\naddresses this crucial question by estimating the pressure exerted by oriented\nice columns on a supramolecular probe composed of a lipid lamellar hydrogel\nduring directional freezing. This process, also known as freeze-casting, has\nemerged as a unique processing technique for a broad class of organic,\ninorganic, soft and biological materials. Nonetheless, the pressure exerted\nduring and after crystallization between two ice columns is not known, despite\nits importance with respect to the fragility of the frozen material, especially\nfor biological samples. By using the lamellar period of a glycolipid lamellar\nhydrogel as a common probe, we couple data obtained from ice-templated-resolved\nin situ synchrotron Small Angle X-ray Scattering (SAXS) with data obtained from\ncontrolled adiabatic dessication experiments. We estimate the pressure to vary\nbetween 1 $\\pm$ 10% kbar at-15{\\textdegree}C and 3.5 $\\pm$ 20% kbar\nat-60{\\textdegree}C.",
        "positive": "Separation of interacting active particles in an asymmetric channel: We study the diffusive behaviour of interacting active particles\n(self-propelled) with mass $m$ in an asymmetric channel. The particles are\nsubjected to an external oscillatory force along the length of the channel. In\nthis setup, particles may exhibit rectification. In the absence of interaction,\nthe mean velocity $\\langle v \\rangle$ of the particles shows a maximum at\nmoderate $m$ values. It means that particles of moderate $m$ have higher\nvelocities than the others. However, by incorporating short-range interaction\nbetween the particles, $\\langle v \\rangle$ exhibits an additional peak at lower\n$m$ values, indicating that particles of lower and moderate m can be separated\nsimultaneously from the rest. Furthermore, by tuning the interaction strength,\nthe self-propelled velocity, and the parameters of the oscillatory force, one\ncan selectively separate the particles of lower $m$, moderate $m$, or both.\nEmpirical relations for estimating the optimal mass as a function of these\nparameters are discussed. These findings are beneficial for separating the\nparticles of selective $m$ from the rest of the particles."
    },
    {
        "anchor": "Kinetics of the helix-coil transition: Based on the Zimm-Bragg model we study cooperative helix-coil transition\ndriven by a finite-speed change of temperature. There is an asymmetry between\nthe coil-to-helix and helix-to-coil transition: the latter is displayed already\nfor finite speeds, and takes shorter time than the former. This hysteresis\neffect has been observed experimentally, and it is explained here via\nquantifying system's stability in the vicinity of the critical temperature. A\nfinite-speed cooling induces a non-equilibrium helical phase with the\ncorrelation length larger than in equilibrium. In this phase the characteristic\nlength of the coiled domain and the non-equilibrium specific heat can display\nan anomalous response to temperature changes. Several pertinent experimental\nresults on the kinetics helical biopolymers are discussed in detail.",
        "positive": "Ductile-to-brittle transition and yielding in soft amorphous materials:\n  perspectives and open questions: Soft amorphous materials are viscoelastic solids ubiquitously found around\nus, from clays and cementitious pastes to emulsions and physical gels\nencountered in food or biomedical engineering. Under an external deformation,\nthese materials undergo a noteworthy transition from a solid to a liquid state\nthat reshapes the material microstructure. This yielding transition was the\nmain theme of a workshop held from January 9 to 13, 2023 at the Lorentz Center\nin Leiden. The manuscript presented here offers a critical perspective on the\nsubject, synthesizing insights from the various brainstorming sessions and\ninformal discussions that unfolded during this week of vibrant exchange of\nideas. The result of these exchanges takes the form of a series of open\nquestions that represent outstanding experimental, numerical, and theoretical\nchallenges to be tackled in the near future."
    },
    {
        "anchor": "Three-dimensional \"Mercedes-Benz\" model for water: In this paper we introduce a three-dimensional version of the Mercedes-Benz\nmodel to describe water molecules. In this model van der Waals interactions and\nhydrogen bonds are given explicitly through a Lennard-Jones potential and a\nGaussian orientation-dependent terms, respectively. At low temperature the\nmodel freezes forming Ice-I and it reproduces the main peaks of the\nexperimental radial distribution function of water. In addition to these\nstructural properties, the model also captures the thermodynamical anomalies of\nwater: the anomalous density profile, the negative thermal expansivity, the\nlarge heat capacity and the minimum in the isothermal compressibility.",
        "positive": "Collective behavior of active molecules: dynamic clusters, holes and\n  active fractalytes: Recent experiments have led to active colloidal molecules which aggregate\nfrom non-motile building blocks and acquire self-propulsion through their\nnon-reciprocal interactions. Here, we model the collective behavior of such\nactive molecules and predict, besides dynamic clusters, the existence of a\nso-far unknown state of active matter made of 'active fractalytes' which are\nmotile crystallites featuring internal holes, gaps and a fractal dimension.\nThese structures could serve as a starting point for the creation of active\nmaterials with a low density and mechanical properties that can be designed\nthrough their fractal internal structure."
    },
    {
        "anchor": "Discontinuous transition in electrolyte flow through charge-patterned\n  nanochannels: We investigate the flow of an electrolyte through a rigid nanochannel\ndecorated with a surface charge pattern. Employing lattice Boltzmann and\ndissipative particle dynamics methods, as well as analytical theory, we show\nthat the electro-hydrodynamic coupling leads to two distinct flow regimes. The\naccompanying discontinuous transition between slow, ionic, and fast, Poiseuille\nflows is observed at intermediate ion concentrations, channel widths, and\nelectrostatic coupling strengths. These findings indicate routes to design\nnanochannels containing a typical aqueous electrolyte that exhibit a digital\non/off flux response, which could be useful for nanofluidics and ionotronic\napplications.",
        "positive": "Mode coupling behavior of a Lennard Jones binary mixture: a comparison\n  between bulk and confined phases: We present a quantitative comparison at equivalent thermodynamical conditions\nof bulk and confined dynamical properties of a Lennard Jones binary mixture\nupon supercooling. Both systems had been previously found to display a behavior\nin agreement with the Mode Coupling theory of the evolution of glassy dynamics.\nDifferences and analogies of behavior are discussed focusing in particular on\nthe role of hopping in reducing spatially correlated dynamics in the confined\nsystem with respect to the bulk."
    },
    {
        "anchor": "FCS and RICS Spectra of Probes in Complex Fluids: The Fluorescence Correlation Spectroscopy (FCS) spectrum G(t) and Raster\nImage Correlation Spectroscopy (RICS) spectrum R(t) of dilute diffusing\nparticles are determined by the displacement distribution function P(x,t) of\nthe particles and by the experimental parameters of the associated optical\ntrains. This letter obtains the general relationships between P(x,t) and these\nspectra. For dilute diffusing molecules in simple liquids, P(x,t) is a Gaussian\nin the displacement x; the corresponding G(t) is a Lorentzian in\n(<(x(t))^2>)^(1/2). In complex fluids such as polymer solutions, colloid and\nprotein solutions, and the interior of living cells, P(x,t) may have a\nnon-Gaussian dependence on x, for example an exponential in |x|. We compare\ntheoretical forms for FCS and for RICS spectra of two systems in which P(x,t)\nis a Gaussian or an exponential in x, but in which the mean-square\ndisplacements are precisely equal at all times. If the G(t) and R(t) arising\nfrom an exponential P(x,t) are interpreted by using the forms for G(t) and R(t)\nthat are appropriate for a Gaussian P(x,t), the inferred diffusion coefficient\nmay be substantially in error.",
        "positive": "MR Imaging of Reynolds Dilatancy in the Bulk of Smooth Granular Flows: Dense granular matter has to expand in order to flow, a phenomenon known as\ndilatancy. Here we perform, by means of Magnetic Resonance Imaging, direct\nmeasurements of the evolution of the local packing density of a slow and smooth\ngranular shear flow generated in a split-bottomed geometry. The dilatancy is\nfound to be surprisingly strong. The dilated zone follow the region of large\nstrain rate and slowly spreads as a function of time. This suggests that the\nlocal packing density is governed by the total amount of local strain\nexperienced since the start of the experiment."
    },
    {
        "anchor": "Migration, trapping, and venting of gas in a soft granular material: Gas migration through a soft granular material involves a strong coupling\nbetween the motion of the gas and the deformation of the material. This process\nis relevant to a variety of natural phenomena, such as gas venting from\nsediments and gas exsolution from magma. Here, we study this process\nexperimentally by injecting air into a quasi-2D packing of soft particles and\nmeasuring the morphology of the air as it invades and then rises due to\nbuoyancy. We systematically increase the confining pre-stress in the packing by\ncompressing it with a fluid-permeable piston, leading to a gradual transition\nin migration regime from fluidization to pathway opening to pore invasion. We\nfind that mixed migration regimes emerge at intermediate confinement due to the\nspontaneous formation of a compaction layer at the top of the flow cell. By\nconnecting these migration mechanisms with macroscopic invasion, trapping, and\nventing, we show that mixed regimes enable a sharp increase in the average\namount of gas trapped within the packing, as well as much larger venting\nevents. Our results suggest that the relationship between invasion, trapping,\nand venting could be controlled by modulating the confining stress.",
        "positive": "Towards Biochemical Filter with Sigmoidal Response to pH Changes:\n  Buffered Biocatalytic Signal Transduction: We realize a biochemical filtering process by introducing a buffer in a\nbiocatalytic signal-transduction logic system based on the function of an\nenzyme, esterase. The input, ethyl butyrate, is converted into butyric acid-the\noutput signal, which in turn is measured by the drop in the pH value. The\ndeveloped approach offers a versatile \"network element\" for increasing the\ncomplexity of biochemical information processing systems. Evaluation of an\noptimal regime for quality filtering is accomplished in the framework of a\nkinetic rate-equation model."
    },
    {
        "anchor": "Interfacial strength dominates fold formation in microscale, soft static\n  friction: Utilizing colloidal probe, lateral force microscopy and simultaneous confocal\nmicroscopy, combined with finite element analysis, we investigate the mechanism\nof static friction for a microparticle on a soft, adhesive surface. We find\nthat the surface can form a self-contacting fold at the leading front, which\nresults from a buildup of compressive stress. A sufficiently high lateral\nresistance is required for folding to occur, although the folds themselves do\nnot increase the peak force. Experimentally, folds are observed on substrates\nthat exhibit both high and low normal adhesion, motivating the use of\nsimulations to consider the role of adhesion energy and interfacial strength.\nOur simulations illustrate that the interfacial strength plays a dominating\nrole in the formation of folds, rather than the overall adhesion energy. These\nresults reveal that adhesion energy alone is not sufficient to predict the\nnucleation of folds or the lateral force, but instead the specific parameters\nthat define the adhesion energy must be considered.",
        "positive": "Radial distribution function of Lennard-Jones fluids in shear flows from\n  intermediate asymptotics: Determining the microstructure of colloidal suspensions under shear flows has\nbeen a challenge for theoretical and computational methods due to the\nsingularly-perturbed boundary-layer nature of the problem. Previous approaches\nhave been limited to the case of hard-sphere systems and suffer from various\nlimitations in their applicability. We present a new analytic scheme based on\nintermediate asymptotics which solves the Smoluchowski diffusion-convection\nequation including both intermolecular and hydrodynamic interactions. The\nmethod is able to recover previous results for the hard-sphere fluid and, for\nthe first time, to predict the radial distribution function (rdf) of attractive\nfluids such as the Lennard-Jones (LJ) fluid. In particular, a new depletion\neffect is predicted in the rdf of the LJ fluid under shear. This method can be\nused for the theoretical modelling and understanding of real fluids subjected\nto flow, with applications ranging from chemical systems to colloids, rheology,\nplasmas, and atmospherical science."
    },
    {
        "anchor": "Shear-Driven Flow of Athermal, Frictionless, Spherocylinder Suspensions\n  in Two Dimensions: Spatial Structure and Correlations: We use numerical simulations to study the flow of athermal, frictionless,\nsoft-core two dimensional spherocylinders driven by a uniform steady-state\nsimple shear applied at a fixed volume and a fixed finite strain rate\n$\\dot\\gamma$. Energy dissipation is via a viscous drag with respect to a\nuniformly sheared host fluid, giving a simple model for flow in a non-Brownian\nsuspension with Newtonian rheology. We study the resulting spatial structure of\nthe sheared system, and compute correlation functions of the velocity, the\nparticle density, the nematic order parameter, and the particle angular\nvelocity. Correlations of density, nematic order, and angular velocity are\nshown to be short ranged both below and above jamming. We compare a system of\nsize-bidisperse particles with a system of size-monodisperse particles, and\nargue how differences in spatial order as the packing increases leads to\ndifferences in the global nematic order parameter. We consider the effect of\nshearing on initially well ordered configurations, and show that in many cases\nthe shearing acts to destroy the order, leading to the same steady-state\nensemble as found when starting from random initial configurations.",
        "positive": "Entropy of jammed matter: We investigate the nature of randomness in disordered packings of frictional\nspheres. We calculate the entropy of 3D packings through the force and volume\nensemble of jammed matter, a mesoscopic ensemble and numerical simulations\nusing volume fluctuation analysis and graph theoretical methods. Equations of\nstate are obtained relating entropy, volume fraction and compactivity\ncharacterizing the different states of jammed matter. At the mesoscopic level\nthe entropy vanishes at random close packing. The entropy of the jammed system\nreveals that the random loose packings are more disordered than random close\npackings, allowing for an unambiguous interpretation of both limits."
    },
    {
        "anchor": "Jet-driven viscous locomotion of confined thermoresponsive microgels: We consider the dynamics of micro-sized, asymmetrically-coated\nthermoresponsive hydrogel ribbons (microgels) under periodic heating and\ncooling in the confined space between two planar surfaces. As the result of the\ntemperature changes, the volume and thus the shape of the slender microgel\nchange, which lead to repeated cycles of bending and elastic relaxation, and to\nnet locomotion. Small devices designed for biomimetic locomotion need to\nexploit flows that are not symmetric in time (non-reciprocal) to escape the\nconstraints of the scallop theorem and undergo net motion. Unlike other\nbiological slender swimmers, the non-reciprocal bending of the gel centreline\nis not sufficient here to explain for the overall swimming motion. We show\ninstead that the swimming of the gel results from the flux of water\nperiodically emanating from (or entering) the gel itself due to its shrinking\n(or swelling). The associated flows induce viscous stresses that lead to a net\npropulsive force on the gel. We derive a theoretical model for this hypothesis\nof jet-driven propulsion, which leads to excellent agreement with our\nexperiments.",
        "positive": "Reentrant Network Formation in Patchy Colloidal Mixtures under Gravity: We study a two-dimensional binary mixture of patchy colloids in\nsedimentation-diffusion-equilibrium using Monte Carlo simulation and Wertheim's\ntheory. By tuning the buoyant masses of the colloids we can control the\ngravity-induced sequence of fluid stacks of differing density and percolation\nproperties. We find complex stacking sequences with up to four layers and\nreentrant network formation, consistently in simulations and theoretically\nusing only the bulk phase diagram as input. Our theory applies to general\npatchy colloidal mixtures and is relevant to understanding experiments under\ngravity."
    },
    {
        "anchor": "Glass transition and alpha-relaxation dynamics of thin films of labeled\n  polystyrene: The glass transition temperature and relaxation dynamics of the segmental\nmotions of thin films of polystyrene labeled with a dye,\n4-[N-ethyl-N-(hydroxyethyl)]amino-4-nitraozobenzene (Disperse Red 1, DR1) are\ninvestigated using dielectric measurements. The dielectric relaxation strength\nof the DR1-labeled polystyrene is approximately 65 times larger than that of\nthe unlabeled polystyrene above the glass transition, while there is almost no\ndifference between them below the glass transition. The glass transition\ntemperature of the DR1-labeled polystyrene can be determined as a crossover\ntemperature at which the temperature coefficient of the electric capacitance\nchanges from the value of the glassy state to that of the liquid state. The\nglass transition temperature of the DR1-labeled polystyrene decreases with\ndecreasing film thickness in a reasonably similar manner to that of the\nunlabeled polystyrene thin films. The dielectric relaxation spectrum of the\nDR1-labeled polystyrene is also investigated. As thickness decreases, the\n$\\alpha$-relaxation time becomes smaller and the distribution of the\n$\\alpha$-relaxation times becomes broader. These results show that thin films\nof DR1-labeled polystyrene are a suitable system for investigating confinement\neffects of the glass transition dynamics using dielectric relaxation\nspectroscopy.",
        "positive": "A fully solvable equilibrium self-assembly process: fine tuning the\n  clusters size and the connectivity in patchy particle systems: Self-assembly is the mechanism that controls the formation of well defined\nstructures from disordered pre-existing parts. Despite the importance of\nself-assembly as a manufacturing method and the increasingly large number of\nexperimental realizations of complex self-assembled nano aggregates,\ntheoretical predictions are lagging behind. Here we show that for a non-trivial\nself-assembly phenomenon, originating branched loop-less clusters, it is\npossible to derive a fully predictive parameter-free theory of equilibrium\nself-assembly by combining the Wertheim theory for associating liquids with the\nFlory-Stockmayer approach for chemical gelation."
    },
    {
        "anchor": "Charge Regulation of Colloidal Particles: Theory and Simulations: To explore charge regulation (CR) in physicochemical and biophysical systems,\nwe present a model of colloidal particles with sticky adsorption sites which\naccount for the formation of covalent bonds between the hydronium ions and the\nsurface functional groups. Using this model and Monte Carlo simulations, we\nfind that the standard Ninham and Parsegian (NP) theory of CR leads to results\nwhich deviate significantly from computer simulations. The problem of NP\napproach is traced back to the use of bulk equilibrium constant to account for\nsurface chemical reactions. To resolve this difficulty we present a new theory\nof CR. The fundamental ingredient of the new approach is the sticky length,\nwhich is non-trivially related with the bulk equilibrium constant. The theory\nis found to be in excellent agreement with computer simulations, without any\nadjustable parameters. As an application of the theory we calculate the\neffective charge of colloidal particles containing carboxyl groups, as a\nfunction of pH and salt concentration.",
        "positive": "On the confinement of semiflexible chains under torsion: The effect of a finite torque on semiflexible polymers in a confined\nenvironment is investigated. It is shown how a new lengthscale appears in the\nstrongly confined limit. The influence of a torque on the extension of\nbiopolymers in nanochannels is also touched upon and it is argued that the\npresence of a torque has a strong influence on the dimensions of nanochannels\nneeded to prevent hairpins."
    },
    {
        "anchor": "Onset of criticality in hyper-auxetic polymer networks: Against common sense, auxetic materials expand or contract perpendicularly\nwhen stretched or compressed, respectively, by uniaxial strain, being\ncharacterized by a negative Poisson's ratio $\\nu$. The amount of deformation in\nresponse to the applied force can be at most equal to the imposed one, so that\n$\\nu=-1$ is the lowest bound for the mechanical stability of solids, a\ncondition here defined as \"hyper-auxeticity\". In this work, we numerically show\nthat ultra-low-crosslinked polymer networks under tension display hyper-auxetic\nbehavior at a finite crosslinker concentration. At this point, the nearby\nmechanical instability triggers the onset of a critical-like transition between\ntwo states of different densities. This phenomenon displays similar features as\nwell as important differences with respect to gas-liquid phase separation.\nSince our model is able to faithfully describe real-world hydrogels, the\npresent results can be readily tested in laboratory experiments, paving the way\nto explore this unconventional phase behavior.",
        "positive": "Dilatancy, Jamming, and the Physics of Granulation: Granulation is a process whereby a dense colloidal suspension is converted\ninto pasty granules (surrounded by air) by application of shear. Central to the\nstability of the granules is the capillary force arising from the interfacial\ntension between solvent and air. This force appears capable of maintaining a\nsolvent granule in a jammed solid state, under conditions where the same amount\nof solvent and colloid could also exist as a flowable droplet. We argue that in\nthe early stages of granulation the physics of dilatancy, which requires that a\npowder expand on shearing, is converted by capillary forces into the physics of\narrest. Using a schematic model of colloidal arrest under stress, we speculate\nupon various jamming and granulation scenarios. Some preliminary experimental\nresults on aspects of granulation in hard-sphere colloidal suspensions are also\nreported."
    },
    {
        "anchor": "Nonequilibrium growth of patchy-colloid networks on substrates: Patchy colloids with highly directional interactions are ideal building\nblocks to control the local arrangements resulting from their spontaneous\nself-organization. Here we propose their use, combined with substrates and\nnonequilibrium conditions, to obtain structures, different from those of\nequilibrium thermodynamic phases. Specifically, we investigate numerically the\nirreversible adhesion of three-patch colloids near attractive substrates, and\nanalyze the fractal network of connected particles that is formed. The network\ndensity profile exhibits three distinct regimes, with different structural and\nscaling properties, which we characterize in detail. The adsorption of a\nmixture of three- and two-patch colloids is also considered. An optimal\nfraction of two-patch colloids is found where the total density of the film is\nmaximized, in contrast to the equilibrium gel structures where a monotonic\ndecrease of the density has been reported.",
        "positive": "Dynamic optical rectification and delivery of active particles: We use moving light patterns to control the motion of {\\it Escherichia coli}\nbacteria whose motility is photo-activated. Varying the pattern speed controls\nthe magnitude and direction of the bacterial flux, and therefore the\naccumulation of cells in up- and down-stream reservoirs. We validate our\nresults with two-dimensional simulations and a 1-dimensional analytic model,\nand use these to explore parameter space. We find that cell accumulation is\ncontrolled by a competition between directed flux and undirected, stochastic\ntransport. We articulate design principles for using moving light patterns and\nlight-activated micro-swimmers to achieve particular experimental goals."
    },
    {
        "anchor": "Strain localization and anisotropic correlations in a mesoscopic model\n  of amorphous plasticity: A mesoscopic model for shear plasticity of amorphous materials in two\ndimensions is introduced, and studied through numerical simulations in order to\nelucidate the macroscopic (large scale) mechanical behavior. Plastic\ndeformation is assumed to occur through a series of local reorganizations.\nUsing a discretization of the mechanical fields on a discrete lattice, local\nreorganizations are modeled as local slip events. Local yield stresses are\nrandomly distributed in space and invariant in time. Each plastic slip event\ninduces a long-ranged elastic stress redistribution. Rate and thermal effects\nare not discussed in the present study. Extremal dynamics allows for recovering\nmany of the complex features of amorphous plasticity observed experimentally\nand in numerical atomistic simulations in the quasi-static regime. In\nparticular, a quantitative picture of localization, and of the anisotropic\nstrain correlation both in the initial transient regime, and in the steady\nstate are provided. In addition, the preparation of the amorphous sample is\nshown to have a crucial effect of on the localization behavior.",
        "positive": "Phase Separation in Soft Matter: Concept of Dynamic Asymmetry: Phase separation is a fundamental phenomenon that produces spatially\nheterogeneous patterns in soft matter. In this Lecture Note we show that phase\nseparation in these materials generally belongs to what we call \"viscoelastic\nphase separation\", where the morphology is determined by the mechanical balance\nof not only the thermodynamic force (interface tension) but also the\nviscoelastic force. The origin of the viscoelastic force is dynamic asymmetry\nbetween the components of a mixture, which can be caused by either a size\ndisparity or a difference in the glass transition temperature between the\ncomponents. We stress that such dynamic asymmetry generally exists in soft\nmatter. The key is that dynamical asymmetry leads to a non-trivial coupling\nbetween the concentration, velocity, and stress fields. Viscoelastic phase\nseparation can be explained by viscoelastic relaxation in pattern evolution and\nthe resulting switching of the relevant order parameter, which are induced by\nthe competition between the deformation rate of phase separation and the\nslowest mechanical relaxation rate of a system. We also discuss an intimate\nlink of viscoelastic phase separation, where deformation fields are\nspontaneously generated by phase separation itself, to mechanical instability\n(or fracture) of glassy material, which is induced by externally imposed strain\nfields. We propose that all these phenomena can be understood as\nmechanically-driven inhomogeneization in a unified manner."
    },
    {
        "anchor": "Partial Clustering in Binary Two-Dimensional Colloidal Suspensions: Strongly interacting binary mixtures of superparamagnetic colloidal particles\nconfined to a two-dimensional water-air interface are examined by theory,\ncomputer simulation and experiment. The mixture exhibits a partial clustering\nin equilibrium: in the voids of the matrix of unclustered big particles, the\nsmall particles form subclusters with a sponge-like topology which is\naccompanied by a characteristic small-wave vector peak in the small-small\nstructure factor. This partial clustering is a general phenomenon occurring for\nstrongly coupled negatively non-additive mixtures.",
        "positive": "Chiral Symmetry Breaking in Bent-Core Liquid Crystals: By molecular modeling we demonstrate that the nematic long-range order\ndiscovered in bent-core liquid crystal systems should reveal further spatially\nhomogeneous phases. Two of them are identified as a tetrahedratic nematic\n($N_T$) phase with $D_{2d}$ symmetry and a chiral tetrahedratic nematic\n($N_T^*$) phase with $D_2$ symmetry. These new phases were found for a lattice\nmodel with quadrupolar and octupolar anisotropic interactions using Mean Field\ntheory and Monte Carlo simulations. The phase diagrams exhibit tetrahedratic\n($T$), $N_T$ and $N_T^*$ phases, in addition to ordinary isotropic ($I$),\nuniaxial nematic ($N_U$) and biaxial nematic ($N_B$) phases. To our knowledge,\nthis is the first molecular model with spontaneous chiral symmetry breaking in\nnon-layered systems."
    },
    {
        "anchor": "Self-assembly of three-dimensional open structures using patchy\n  colloidal particles: Open structures can display a number of unusual properties, including a\nnegative Poisson's ratio, negative thermal expansion, and holographic\nelasticity, and have many interesting applications in engineering. However, it\nis a grand challenge to self-assemble open structures at the colloidal scale,\nwhere short-range interactions and low coordination number can leave them\nmechanically unstable. In this paper we discuss the self-assembly of open\nstructures using triblock Janus particles, which have two large attractive\npatches that can form multiple bonds, separated by a band with purely\nhard-sphere repulsion. Such surface patterning leads to open structures that\nare stabilized by orientational entropy (in an order-by-disorder effect) and\nselected over close-packed structures by vibrational entropy. For different\npatch sizes the particles can form into either tetrahedral or octahedral\nstructural motifs which then compose open lattices, including the pyrochlore,\nthe hexagonal tetrastack and the perovskite lattices. Using an analytic theory,\nwe examine the phase diagrams of these possible open and close-packed\nstructures for triblock Janus particles and characterize the mechanical\nproperties of these structures. Our theory leads to rational designs of\nparticles for the self-assembly of three-dimensional colloidal structures that\nare possible using current experimental techniques.",
        "positive": "Increasing granular flow rate with obstructions: We describe a simple experiment involving spheres rolling down an inclined\nplane towards a bottleneck and through a gap. Results of the experiment\nindicate that flow rate can be increased by placing an obstruction at optimal\npositions near the bottleneck. We use the experiment to develop a computer\nsimulation using the PhysX physics engine. Simulations confirm the experimental\nresults and we state several considerations necessary to obtain a model that\nagrees well with experiment. We demonstrate that the model exhibits clogging,\nintermittent and continuous flow, and that it can be used as a tool for further\ninvestigations in granular flow."
    },
    {
        "anchor": "Entropy Driven Phase Separation in a Model Colloid-Polymer Mixture: A grand canonical Monte Carlo method for the simulation of a simple\ncolloid-polymer mixture called the AO model will be described. The phase\nseparation known to occur in this model is driven by entropy. The phase diagram\nof the unmixing transition, the surface tension and thecritical point will be\ndetermined.\n  To appear in: \"Computer Simulation Studies in Condensed Matter Physics XVIII,\nEds. D.P. Landau, S.P. Lewis, and H.B. Schuettler (Springer Verlag, Heidelberg,\nBerlin, 2004).",
        "positive": "Flux reversal in a two-state symmetric optical thermal ratchet: A Brownian particle's random motions can be rectified by a periodic potential\nenergy landscape that alternates between two states, even if both states are\nspatially symmetric. If the two states differ only by a discrete translation,\nthe direction of the ratchet-driven current can be reversed by changing their\nrelative durations. We experimentally demonstrate flux reversal in a symmetric\ntwo-state ratchet by tracking the motions of colloidal spheres moving through\nlarge arrays of discrete potential energy wells created with dynamic\nholographic optical tweezers. The model's simplicity and high degree of\nsymmetry suggest possible applications in molecular-scale motors."
    },
    {
        "anchor": "Scaling law of the disjoining pressure reveals two dimensional structure\n  of polymeric fluids: A scaling relation for the disjoining pressure of strongly confined polymer\nfluids is proposed for the first time, which yields directly the scaling\nexponent, nu, of the radius of gyration for polymers. To test the proposed\nscaling relation we performed extensive particle based, coarse grained computer\nsimulations of polymers confined under theta solvent conditions and found that\nthe value of nu agrees with the expected value for strictly two dimensional\nchains, nu = 4/7, which points towards the essential correctness of our scaling\nrelation. New approaches are suggested for experimental tests of this scaling\nlaw. This work opens up the way to look for other scaling exponents that may\nreveal new physical regimes and it constitutes an efficient route to determine\nnu because the scaling exponent can be obtained with chains of a single\npolymerization degree by simply reducing the distance between the confining\nplates.",
        "positive": "Nonlinear model of ice surface softening during friction: The ice surface softening during friction is shown as a result of spontaneous\nappearance of shear strain caused by external supercritical heating. This\ntransformation is described by the Kelvin-Voigt equation for viscoelastic\nmedium, by the relaxation equations of Landau-Khalatnikov-type and for heat\nconductivity. The study reveals that the above-named equations formally\ncoincide with the synergetic Lorenz system, where the order parameter is\nreduced to shear strain, stress acts as the conjugate field, and temperature\nplays the role of a control parameter. Using the adiabatic approximation, the\nstationary values of these quantities are derived. The examination of\ndependence of the relaxed shear modulus on strain explains the ice surface\nsoftening according to the first-order transition mechanism. The critical\nheating rate is proportional to the relaxed value of the ice shear modulus and\ninversely proportional to its typical value."
    },
    {
        "anchor": "A glass transition scenario based on heterogeneities and entropy\n  barriers: We propose a scenario for the glass transition based on the cooperative\nnature of nucleation processes and entropic effects. The main point is the\nrelation between the off-equilibrium energy dissipation and nucleation\nprocesses in off-equilibrium supercooled liquids which leads to a natural\ndefinition of the complexity. From the absence of coarsening growth we can\nderive an entropy based fluctuation formula which relates the free energy\ndissipation rate in the glass with the nucleation rate of the largest\ncooperative regions. As by-product we obtain a new phenomenological relation\nbetween the largest relaxation time in the supercooled liquid phase and an\neffective temperature. This differs from the Adam-Gibbs relation in that\npredicts no divergence of the primary relaxation time at the Kauzmann\ntemperature and the existence of a crossover from fragile to strong behavior.",
        "positive": "Slow Relaxations of Chemically Confined Hydration Layers near Lipid\n  Bilayers: Dynamical Heterogeneities above Supercooling: A hydrated 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) lipid\nmembrane is investigated using an all atom molecular dynamics simulation at\n308K to find out the physical sources of universal slow relaxation of hydration\nlayers. Continuously residing interface water (IW) hydrogen bonded to each\nother and concertedly to different moieties of lipid heads are identified. The\nnon-gaussian parameter of all IW show a crossover from cage vibration to\ntranslational diffusion. A significant non-gaussianity is observed for the IW\nprevailing large length correlations in translational van Hove functions. Two\ntime-scales for the ballisitic motions and hopping transitions are obtained\nfrom the self intermediate scattering functions of the IW with an additional\nlong relaxation which disappears for the BW. This is attributed to the coupled\ndynamics of IW cages hydrogen bonded to lipid heads. Our calculations reveal\nthat the water near membranes are slowed down due to dynamical heterogeneities\nabove room temperature and have implications to bioprotection mechanism at\nfreezing conditions."
    },
    {
        "anchor": "Lateral phase separation in mixtures of lipids and cholesterol systems: In an effort to understand ``rafts'' in biological membranes, we propose\nphenomenological models for saturated and unsaturated lipid mixtures, and\nlipid-cholesterol mixtures. We consider simple couplings between the local\ncomposition and internal membrane structure, and their influence on transitions\nbetween liquid and ``gel'' membrane phases. Assuming that the gel transition\ntemperature of the saturated lipid is shifted by the presence of the\nunsaturated lipid, and that cholesterol acts as an external field on the chain\nmelting transition, a variety of phase diagrams are obtained. The phase\ndiagrams for binary mixtures of saturated/unsaturated lipids and\nlipid/cholesterol are in semi-quantitative agreement with the experiments. Our\nresults also apply to regions in the ternary phase diagram of\nlipid/lipid/cholesterol systems.",
        "positive": "Fluid-driven slow slip and earthquake nucleation on a slip-weakening\n  circular fault: We investigate the propagation of fluid-driven fault slip on a slip-weakening\nfrictional interface separating two identical half-spaces of a\nthree-dimensional elastic solid. Our focus is on axisymmetric circular shear\nruptures as they capture the most essential aspects of the dynamics of\nunbounded ruptures in three dimensions. In our model, fluid-driven aseismic\nslip occurs in two modes: as an interfacial rupture that is unconditionally\nstable, or as the quasi-static nucleation phase of an otherwise dynamic\nrupture. Unconditionally stable ruptures progress through four stages.\nInitially, ruptures are diffusively self-similar and the interface behaves as\nif it were governed by a constant friction coefficient equal to the static\nfriction value. Slip then accelerates due to frictional weakening while the\ncohesive zone develops. Once the latter gets properly localized, a finite\namount of fracture energy emerges along the interface and the rupture dynamics\nis governed by an energy balance of the Griffith's type. In this stage, fault\nslip transition from a large-toughness to a small-toughness regime. Ultimately,\nself-similarity is recovered and the fault behaves again as having a constant\nfriction coefficient, but this time equal to the dynamic friction value. When\nslow slip is the result of a frustrated dynamic instability, slip also\ninitiates self-similarly at a constant peak friction coefficient. The maximum\naseismic rupture size varies from a critical nucleation radius (shear modulus\ndivided by slip-weakening rate) to infinity near the limit that separates the\ntwo modes of aseismic sliding. We provide analytical and numerical solutions\nfor the problem solved over its full dimensionless parameter space. Due to its\nthree-dimensional nature, the model enables quantitative comparisons with field\nobservations as well as preliminary engineering design of hydraulic stimulation\noperations."
    },
    {
        "anchor": "Correcting the polarization effect in low frequency Dielectric\n  Spectroscopy: We demonstrate a simple and robust methodology for measuring and analyzing\nthe polarization impedance appearing at interface between electrodes and ionic\nsolutions, in the frequency range from 1 to $10^6$ Hz. The method assumes no\nparticular behavior of the electrode polarization impedance and it only makes\nuse of the fact that the polarization effect dies out with frequency. The\nmethod allows a direct and un-biased measurement of the polarization impedance,\nwhose behavior with the applied voltages and ionic concentration is\nmethodically investigated. Furthermore, based on the previous findings, we\npropose a protocol for correcting the polarization effect in low frequency\nDielectric Spectroscopy measurements of colloids. This could potentially lead\nto the quantitative resolution of the $\\alpha$-dispersion regime of live cells\nin suspension.",
        "positive": "The interplay between phase-separation and gene-enhancer communication:\n  a theoretical study: The phase-separation occurring in a system of mutually interacting proteins\nthat can bind on specific sites of a chromatin fiber is here investigated. This\nis achieved by means of extensive Molecular Dynamics simulations of a simple\npolymer model which includes regulatory proteins as interacting spherical\nparticles. Our interest is particularly focused on the role played by\nphase-separation in the formation of molecule aggregates that can join distant\nregulatory elements, such as gene promoters and enhancers, along the DNA. We\nfind that the overall equilibrium state of the system resulting from the mutual\ninterplay between binding molecules and chromatin can lead, under suitable\nconditions that depend on molecules concentration, molecule-molecule and\nmolecule-DNA interactions, to the formation of phase-separated molecular\nclusters allowing robust contacts between regulatory sites. Vice-versa, the\npresence of regulatory sites can promote the phase-separation process.\nDifferent dynamical regimes can generate the enhancer-promoter contact, either\nby cluster nucleation at binding sites or by bulk spontaneous formation of the\nmediating cluster to which binding sites are successively attracted. The\npossibility that such processes can explain experimental live-cell imaging data\nmeasuring distances between regulatory sites during time is also discussed."
    },
    {
        "anchor": "Fluid-mediated impact of soft solids: A viscous, lubrication-like response can be triggered in a thin film of fluid\nsqueezed between a rigid and flat surface and the tip of an incoming\nprojectile. We develop a comprehensive theory for this viscous approach stage\nof fluid-mediated normal impact, applicable to soft impactors. Under the\nassumption of mediating fluid being incompressible, the impacting solid\ndisplays two limit regimes: one dominated by elasticity and the other by\ninertia. The transition between the two is predicted by a dimensionless\nparameter, which can be interpreted as the ratio between two time scales that\nare the time that it takes for the surface waves to warn the leading edge of\nthe impactor of the forthcoming impact, and the characteristic duration of the\nfinal viscous phase of the approach. Additionally, we assess the role of solid\ncompressibility and elucidate why nearly-incompressible solids feature (a)\nsubstancial \"gliding\" prior to contact at the transition between regimes, (b)\nthe largest size of entrapped bubble between the deformed tip of the impactor\nand the flat surface, and (c) a sudden drop in entrapped bubble radius past the\ntransition between regimes. Finally, we argue that the above time scale ratio\n(a dimensionless number) can govern the different dynamics reported\nexperimentally for a fluid droplet as a function of its viscosity and surface\ntension.",
        "positive": "Hybrid continuum-discrete simulation of granular impact dynamics: Granular impact -- the dynamic intrusion of solid objects into granular media\n-- is widespread across scientific and engineering applications including\ngeotechnics. Existing approaches for simulating granular impact dynamics have\nrelied on either a pure discrete method or a pure continuum method. Neither of\nthese methods, however, is deemed optimal from the computational perspective.\nHere, we introduce a hybrid continuum-discrete approach, built on the coupled\nmaterial-point and discrete-element method (MP-DEM), for simulating granular\nimpact dynamics with unparalleled efficiency. To accommodate highly complex\nsolid-granular interactions, we enhance the existing MP-DEM formulation with\nthree new ingredients: (i) a robust contact algorithm that couples the\ncontinuum and discrete parts without any interpenetration under extreme impact\nloads, (ii) large deformation kinematics employing multiplicative\nelastoplasticity, and (iii) a trans-phase constitutive relation capturing\ngasification of granular media. For validation, we also generate experimental\ndata through laboratory measurement of the impact dynamics of solid spheres\ndropped onto dry sand. Simulation of the experiments shows that the proposed\napproach can well reproduce granular impact dynamics in terms of impact forces,\nintrusion depths, and splash patterns. Further, through parameter studies on\nmaterial properties, model formulations, and numerical schemes, we identify key\nfactors for successful continuum-discrete simulation of granular impact\ndynamics."
    },
    {
        "anchor": "Long-lived submicrometric bubbles in very diluted alkali halide water\n  solutions: Solutions of LiCl and of NaCl in ultrapure water were studied through\nRayleigh/Brillouin scattering as a function of the concentration (molarity, M)\nof dissolved salt from 0.2M to extremely low concentration (2.10^-17 M ). The\nLandau-Placzek ratio, R/B, of the Rayleigh scattering intensity over the total\nBrillouin, was measured thanks to the dynamically controlled stability of the\nused Fabry-Perot interferometer. It was observed that the R/B ratio follows two\nstages as a function of increasing dilution rate: after a strong decrease\nbetween 0.2M and 2.10^-5 M, it increases to reach a maximum between 10^-9 M and\n10^-16 M. The first stage corresponds to the decrease of the Rayleigh\nscattering by the ion concentration fluctuations with the decrease of salt\nconcentration. The second stage, at lower concentrations, is consistent with\nthe increase of the Rayleigh scattering by long-lived sub-microscopic bubbles\nwith the decrease of ion concentration. The origin of these sub-microscopic\nbubbles is the shaking of the solutions which was carried out after each\ncentesimal dilution. The very long lifetime of the sub-microscopic bubbles and\nthe effects of aging originate in the electric charge of bubbles. The increase\nof R/B with the decrease of the low salt concentration corresponds to the\nincrease of the sub-microscopic bubble size with the decrease of concentration,\nthat is imposed by the bubble stability due to the covering of the surface\nbubble by negative ions.",
        "positive": "Spontaneous Crystallization in Systems of Binary Hard Sphere Colloids: Computer simulations of the fluid-to-solid phase transition in the hard\nsphere system were instrumental for our understanding of crystallization\nprocesses. But while colloid experiments and theory have been predicting the\nstability of several binary hard sphere crystals for many years, simulations\nwere not successful to confirm this phenomenon. Here, we report the growth of\nbinary hard sphere crystals isostructural to Laves phases, AlB$_2$, and\nNaZn$_{13}$ in simulation directly from the fluid. We analyze particle kinetics\nduring Laves phase growth using event-driven molecular dynamics simulations\nwith and without swap moves that speed up diffusion. The crystallization\nprocess transitions from nucleation and growth to spinodal decomposition\nalready deep within the fluid-solid coexistence regime. Finally, we present\npacking fraction-size ratio state diagrams in the vicinity of the stability\nregions of three binary crystals."
    },
    {
        "anchor": "Jamming of Frictional Particles: a Non-equilibrium First Order Phase\n  Transition: We propose a phase diagram for the shear flow of dry granular particles in\ntwo dimensions based on simulations and a phenomenological Landau-theory for a\nnonequilibrium first order phase transition. Our approach incorporates both\nfrictional as well as frictionless particles. The most important feature of the\nfrictional phase diagram is re-entrant flow and a critical jamming point at\nfinite stress. In the frictionless limit the regime of re-entrance vanishes and\nthe jamming transition is continuous with a critical point at zero stress. The\njamming phase diagrams derived from the model agree with the experiments of Bi\net al. (Nature (2011)) and brings together previously conflicting numerical\nresults.",
        "positive": "Discriminating protein tags on dsDNA constructs using a dual Nanopore\n  device: We report a novel simulation strategy that enables us to identify key\nparameters controlling the experimentally measurable characteristics of\nstructural protein tags on dsDNA construct translocating through a double\nnanopore setup. First, we validate the scheme in silico by reproducing and\nexplaining the physical origin of the experimental dwell time distributions of\nthe Streptavidin markers on a 48 kbp long dsDNA. These studies reveal the\nimportant differences in the characteristics of the protein tags compared to\nthe dynamics of dsDNA segments, immediately providing clues on how to improve\nthe measurement protocols to decipher the unknown genomic lengths accurately.\nOf particular importance is the in silico studies on the effect of electric\nfield inside and beyond the pores which we find is critical to discriminate\nprotein tags based on their effective charges and masses revealed through a\ngeneric power-law dependence of the average dwell time at each pore. The\nsimulation protocols enable to monitor piecewise dynamics of the individual\nmonomers at a sub-nanometer length scale and provide an explanation of the\ndisparate velocity variation from one tag to the other using the nonequilibrium\ntension propagation theory, - a key element to decipher genomic lengths\naccurately. We further justify the model and the chosen simulation parameters\nby calculating the Peclet number which is in close agreement with the\nexperiment. Analysis of our simulation results from the CG model has the\ncapability to refine the accuracy of the experimentally obtained genomic\nlengths and carefully chosen simulation strategies can serve as a powerful tool\nto discriminate different types of neutral and charged tags of different\norigins on a dsDNA construct in terms of their physical characteristics and can\nprovide insights to increase both the efficiency and accuracy of an\nexperimental dual-nanopore setup."
    },
    {
        "anchor": "Stress Tensor of Single Rigid Dumbbell by Virtual Work Method: We derive the stress tensor of a rigid dumbbell by using the virtual work\nmethod. In the virtual work method, we virtually apply a small deformation to\nthe system, and relate the change of the energy to the work done by the stress\ntensor. A rigid dumbbell consists of two particles connected by a rigid bond of\nwhich length is constant (the rigid constraint). The energy of the rigid\ndumbbell consists only on the kinetic energy. Also, only the deformations which\ndo not violate the rigid constraint are allowed. Thus we need the dynamic\nequations which is consistent with the rigid constraint to apply the virtual\ndeformation. We rewrite the dynamic equations for the underdamped SLLOD-type\ndynamic equations into the forms which are consistent with the rigid\nconstraint. Then we apply the virtual deformation to a rigid dumbbell based on\nthe obtained dynamic equations. We derive the stress tensor for the rigid\ndumbbell model from the change of the kinetic energy. Finally, we take the\noverdamped limit and derive the stress tensor and the dynamic equation for the\noverdamped rigid dumbbell. We show that the Green-Kubo type linear response\nformula can be reproduced by combining the stress tensor and the dynamic\nequation at the overdamped limit.",
        "positive": "Applications of fractional calculus to diffusion transport in clay-water\n  system: The analysis of the low-frequency conductivity spectra of the clay-water\nmixtures is presented. The conductivity spectra for samples at different water\ncontent values are shown to collapse to a single master curve when\nappropriately rescaled. The frequency dependence of the conductivity is shown\nto follow the power-law with the exponent n=0,67 before reaching the\nfrequency-independent part. It is argued that the observed conductivity\ndispersion is a consequence of the anomalously diffusing ions in the clay-water\nsystem. The fractional Langevin equation is then used to describe the\nstochastic dynamics of the single ion."
    },
    {
        "anchor": "Excess Wings in Broadband Dielectric Spectroscopy: Analysis of excess wings in broadband dielectric spectroscopy data of glass\nforming materials is found to provide evidence for anomalous time evolutions\nand fractional semigroups. Solutions of fractional evolution equations in\nfrequency space are used to fit dielectric spectroscopy data of glass forming\nmaterials with a range between 4 and 10 decades in frequency. We show that with\nonly three parameters (two relaxation times plus one exponent) excellent fits\ncan be obtained for 5-methyl-2-hexanol and for methyl-m-toluate over up to 7\ndecades. The traditional Havriliak-Negami fit with three parameters (two\nexponents and one relaxation time) fits only 4-5 decades. Using a second\nexponent, as in Havriliak-Negami fits, the $\\alpha$-peak and the excess wing\ncan be modeled perfectly with our theory for up to 10 decades for all materials\nat all temperatures considered here. Traditionally this can only be\naccomplished by combining two Havriliak-Negami functions with 6 parameters. The\ntemperature dependent relaxation times are fitted with the\nVogel-Tammann-Fulcher relation which provides the corresponding Vogel-Fulcher\ntemperatures. The relaxation times turn out to obey almost perfectly the\nVogel-Tammann-Fulcher law. Finally we report new and computable expressions of\ntime dependent relaxation functions corresponding to the frequency dependent\ndielectric susceptibilities.",
        "positive": "Hydrodynamic Inflation of Ring Polymers under Shear: Hydrodynamic interactions as modeled by Multi-Particle Collision Dynamics can\ndramatically influence the dynamics of fully flexible, ring-shaped polymers in\nways not known for any other polymer architecture or topology. We show that\nsteady shear leads to an inflation scenario exclusive to ring polymers, which\ndepends not only on Weissenberg number but also on contour length of the ring.\nBy analyzing velocity fields of the solvent around the polymer, we show the\nexistence of a hydrodynamic pocket which allows the polymer to self-stabilize\nat a certain alignment angle to the flow axis. This self-induced stabilization\nis accompanied by transitioning of the ring to a non-Brownian particle and a\ncessation of tumbling. The ring swells significantly in the vorticity\ndirection, and the horseshoe regions on the stretched and swollen ring are\neffectively locked in place relative to the ring's center-of-mass. The observed\neffect is exclusive to ring polymers and stems from an interplay between\nhydrodynamic interactions and topology. Furthermore, knots tied onto such rings\ncan serve as additional \"stabilization anchors\". Under strong shear, the\nknotted section is pulled tight and remains well-localized while tank-treading\nfrom one horseshoe region to the opposite one in sudden bursts. We find knotted\npolymers of high contour length behave very similarly to unknotted rings of the\nsame contour length, but small knotted rings feature a host of different\nconfigurations. We propose a filtering technique for rings and chains based on\nour observations and suggest that strong shear could be used to tighten knots\non rings."
    },
    {
        "anchor": "Kirigami-inspired inflatables with programmable shapes: Kirigami, the Japanese art of paper cutting, has recently enabled the design\nof stretchable mechanical metamaterials that can be easily realized by\nembedding arrays of periodic cuts into an elastic sheet. Here, we exploit\nkirigami principles to design inflatables that can mimic target shapes upon\npressurization. Our system comprises a kirigami sheet embedded into an\nunstructured elastomeric membrane. First, we show that the inflated shape can\nbe controlled by tuning the geometric parameters of the kirigami pattern. Then,\nby applying a simple optimization algorithm, we identify the best parameters\nthat enable the kirigami inflatables to transform into a family of target\nshapes at a given pressure. Furthermore, thanks to the tessellated nature of\nthe kirigami, we show that we can selectively manipulate the parameters of the\nsingle units to allow the reproduction of features at different scales and\nultimately enable a more accurate mimicking of the target.",
        "positive": "Scaling regimes and fluctuations of observables in computer glasses\n  approaching the unjamming transition: Under decompression, disordered solids undergo an unjamming transition where\nthey become under-coordinated and lose their structural rigidity. The\nmechanical and vibrational properties of these materials have been an object of\ntheoretical, numerical, and experimental research for decades. In the study of\nlow-coordination solids, understanding the behavior and physical interpretation\nof observables that diverge near the transition is of particular importance.\nSeveral such quantities are length scales ($\\xi$ or $l$) that characterize the\nsize of excitations, the decay of spatial correlations, the response to\nperturbations, or the effect of physical constraints in the boundary or bulk of\nthe material. Additionally, the spatial and sample-to-sample fluctuations of\nmacroscopic observables such as contact statistics or elastic moduli diverge\napproaching unjamming. Here, we discuss important connections between all of\nthese quantities, and present numerical results that characterize the scaling\nproperties of sample-to-sample contact and shear modulus fluctuations in\nensembles of low-coordination disordered sphere packings and spring networks.\nOverall, we highlight three distinct scaling regimes and two crossovers in the\ndisorder quantifiers $\\chi_z$ and $\\chi_\\mu$ as functions of system size $N$\nand proximity to unjamming $\\delta z$. As we discuss, $\\chi_X$ relates to the\nstandard deviation $\\sigma_X$ of the sample-to-sample distribution of the\nquantity $X$ (e.g. excess coordination $\\delta z$ or shear modulus $\\mu$) for\nan ensemble of systems. Importantly, $\\chi_\\mu$ has been linked to\nexperimentally accessible quantities that pertain to sound attenuation and the\ndensity of vibrational states in glasses."
    },
    {
        "anchor": "Active diffusion of self-propelled particles in flexible polymer\n  networks: Biopolymer networks having a meshwork topology, e.g., extracellular matrix\nand mucus gels, are ubiquitous. It is an open question to understand how\nself-propelled agents such as Janus colloidal particles diffuse through such a\nbiopolymer network. Here, we computationally explore this issue in-depth by\nexplicitly modeling three-dimensional biopolymer networks and performing\nLangevin dynamics simulations of active diffusion of the self-propelled tracers\ntherein. We show that the active tracer performs distinct diffusion dynamics\ndepending on the mesh-to-particle size and P\\'eclet number (Pe). When the\nparticle is smaller than the mesh size, it moves as if in free space with a\ndecreased mobility depending on the polymer occupation density and Pe. However,\nwhen the particle size is increased to be comparable to the mesh size, the\nactive particles explore the polymer network using the trapped-and-hopping\nmechanism. We study the trapped time distribution, flight length distribution,\nthe mean-squared displacement, and the long-time diffusivity at varying Pe. If\nthe particle is larger than the mesh, it captures the collective viscoelastic\ndynamics from the polymer network at short times and the simple diffusion of\nthe total system at large times. Finally, we discuss the scaling behavior of\nthe long-time diffusivity with Pe, where we find a range of Pe that yields a\nnontrivial power law. The latter turns out to arise from a large fluctuation of\ntrapped, activated tracers in conjugation with responsive polymer networks.",
        "positive": "Morphological Transitions during Melting of Small Cylindrical Aggregates: Most studies on melting under confinement focus only on the solid and liquid\nmelt phases. Despite of its ubiquity, contributions from the capillary\ninterface (liquid / vapor interface) are often neglected. In this study the\nmelting behavior of small cylindrical aggregates in vapor attached to planar\nsurfaces is analyzed. For the assumed boundary conditions (cylindrical solid\nwith a non wetting top plane and a wettable side wall) solid and the liquid\nphases can coexist within a certain temperature range. Due to capillary\ninstability, the liquid phase can form either an axisymmetric rouloid\nmorphology or, above a certain threshold liquid volume fraction, a bulge\ncoexisting with a rouloid-like section. The corresponding melting points are\ndifferent. The analysis explicitly describes the behavior of a real system of\nsmall aggregates of long chain alkanes on planar substrates. It also gives\nqualitative insights into the melting behavior of small aggregates with\nanisotropic wetting behaviors in general. It reveals in particular how melting\npoints and melting pathways depend on the energetic respectively morphological\npathways leading to complete melting."
    },
    {
        "anchor": "Transition in the supercritical state of matter: experimental evidence: A large and mostly unexplored part of the phase diagram lies above the\ncritical point. The supercritical matter was traditionally believed to be\nphysically homogeneous with no discernible differences between liquidlike and\ngaslike states. More recently, several proposals have been put forward\nchallenging this view, and here we review the history of this research. Close\nto the critical point, persisting critical anomalies enable the separation of\nthe supercritical state into two different states. About a decade ago, it was\nproposed that the Frenkel line (FL), corresponding to the dynamical transition\nof particle motion and related thermodynamic and structural transitions, gives\na unique and path-independent way to separate the supercritical states into two\nqualitatively different states and extends to arbitrarily high pressure and\ntemperature on the phase diagram. Here, we review several lines of enquiry that\nfollowed. We focus on the experimental evidence of transitions in deeply\nsupercritical Ne, N$_2$, CH$_4$, C$_2$H$_6$, CO$_2$ and H$_2$O at the FL\ndetected by a number of techniques including X-ray, neutron and Raman\nscattering experiments. %Except for H$_2$O, these experiments were stimulated\nby the FL and followed the state points of the FL mapped in preceding\ncalculations. We subsequently summarise other developments in the field,\nincluding recent extensions of analysis of dynamics at the FL, quantum\nsimulations, topological and geometrical approaches as well as universality of\nproperties at the FL. Finally, we review current theoretical understanding of\nthe supercritical state and list open problems in the field.",
        "positive": "Rheology of two-dimensional F-actin networks associated with a lipid\n  interface: We report on the surface rheology of cross-linked F-actin networks associated\nwith a lipid monolayer at the air-water interface of a Langmuir monolayer. The\nrheological measurements are made using a Couette cell. These data demonstrate\nthat the network has a finite elastic modulus that grows as a function of the\ncross-linking concentration. We also note that under steady-state flow the\nsystem behaves as a power law fluid in which the effective viscosity decreases\nwith imposed shear."
    },
    {
        "anchor": "Phase-field-crystal model for liquid crystals: Based on static and dynamical density functional theory, a\nphase-field-crystal model is derived which involves both the translational\ndensity and the orientational degree of ordering as well as a local director\nfield. The model exhibits stable isotropic, nematic, smectic A, columnar,\nplastic crystalline and orientationally ordered crystalline phases. As far as\nthe dynamics is concerned, the translational density is a conserved order\nparameter while the orientational ordering is non-conserved. The derived\nphase-field-crystal model can serve for efficient numerical investigations of\nvarious nonequilibrium situations in liquid crystals.",
        "positive": "A microscopic model for hydrated biological tissues: The present work presents a density-functional microscopic model of soft\nbiological tissue. The model was based on a prototype molecular structure from\nexperimentally resolved collagen peptide residues and water clusters and has\nthe objective to capture some well-known experimental features of soft tissues.\nIt was obtained the optimized geometry, binding and coupling energies and\ndipole moments. The results concerning the stability of the confined water\nclusters, the water-water and water-collagen interactions within the CLBM\nframework were successfully correlated to some important trends observed\nexperimentally in inflammatory tissues."
    },
    {
        "anchor": "Simultaneous photon absorption as a probe of molecular interaction and\n  hydrogen-bond correlation in liquids: We have investigated the simultaneous absorption of near-infrared photons by\npairs of neighboring molecules in liquid methanol. Simultaneous absorption by\ntwo OH-stretching modes is found to occur at an energy higher than the sum of\nthe two absorbing modes. This frequency shift arises from interaction between\nthe modes, and its value has been used to determine the average coupling\nbetween neighboring methanol molecules. We find a rms coupling strength of\n46+/-1 cm-1, much larger than can be explained from transition-dipole coupling,\nsuggesting that hydrogen-bond mediated interactions between neighboring\nmolecules play an important role in liquid methanol. The most important aspect\nof simultaneous vibrational absorption is that it allows for a quantitative\ninvestigation of hydrogen-bond cooperativity. We derive the extent to which the\nhydrogen-bond strengths of neighboring molecules are correlated by comparing\nthe line shape of the absorption band caused by simultaneous absorption with\nthat of the fundamental transition. Surprisingly, neighboring hydrogen bonds in\nmethanol are found to be strongly correlated, and from the data we obtain a\nhydrogen-bond correlation coefficient of 0.69+/-0.12.",
        "positive": "Particle-scale reversibility in athermal particulate media below jamming: We perform numerical simulations of athermal repulsive frictionless disks and\nspheres in two and three spatial dimensions undergoing cyclic quasi-static\nsimple shear to investigate particle-scale reversible motion. We identify three\nclasses of steady-state dynamics as a function of packing fraction \\phi and\nmaximum strain amplitude per cycle \\gamma_{\\rm max}. Point-reversible states,\nwhere particles do not collide and exactly retrace their intra-cycle\ntrajectories, occur at low \\phi and \\gamma_{\\rm max}. Particles in\nloop-reversible states undergo numerous collisions and execute complex\ntrajectories, but return to their initial positions at the end of each cycle.\nLoop-reversible dynamics represents a novel form of self-organization that\nenables reliable preparation of configurations with specified structural and\nmechanical properties over a broad range of \\phi from contact percolation to\njamming onset at \\phi_J. For sufficiently large \\phi and \\gamma_{\\rm max},\nsystems display irreversible dynamics with nonzero self-diffusion."
    },
    {
        "anchor": "A transient network of telechelic polymers and microspheres : structure\n  and rheology: We study the structure and dynamics of a transient network composed of\ndroplets of microemulsion connected by telechelic polymers. The polymer induces\na bridging attraction between droplets without changing their shape. A\nviscoelastic behaviour is induced in the initially liquid solution,\ncharacterised in the linear regime by a stretched exponential stress\nrelaxation. We analyse this relaxation in the light of classical theories of\ntransient networks. The role of the elastic reorganisations in the deformed\nnetwork is emphasized. In the non linear regime, a fast relaxation dynamics is\nfollowed by a second one having the same rate as in the linear regime. This\nbehaviour, under step strain experiments, should induce a non monotonic\nbehaviour in the elastic component of the stress under constant shear rate.\nHowever, we obtain in this case a singularity in the flow curve very different\nfrom the one observed in other systems, that we interpret in terms of fracture\nbehaviour.",
        "positive": "Orientational order and alignment of elongated particles induced by\n  shear: Shear induced alignment of elongated particles is studied experimentally and\nnumerically. We show that shear alignment of ensembles of macroscopic particles\nis comparable even on a quantitative level to simple molecular systems, despite\nthe completely different types of particle interactions. We demonstrate that\nfor dry elongated grains the preferred orientation forms a small angle with the\nstreamlines, independent of shear rate across three decades. For a given\nparticle shape, this angle decreases with increasing aspect ratio of the\nparticles. The shear-induced alignment results in a considerable reduction of\nthe effective friction of the granular material."
    },
    {
        "anchor": "A macroscopic constitutive relation for isotropic-genesis, polydomain\n  liquid crystal elastomers: Liquid crystal elastomers (LCEs) are rubber-like solids that incorporate\nnematic mesogens (stiff rod-like molecules) as a part of their polymer chains.\nIn recent years, isotropic-genesis, polydomain liquid crystal elastomers\n(I-PLCEs) has been a topic of both scientific and technological interest due to\ntheir intriguing properties such as soft behavior, ability to dissipate energy\nand stimuli response, as well as the ease with which they can be synthesized.\nWe present a macroscopic or engineering scale constitutive model of the\nbehavior of I-PLCEs. The model implicitly accounts for the complex evolution of\nthe domain patterns and is able to faithfully capture the experimentally\nobserved complex response to multi-axial loading. We describe a multiscale\nframework that motivates the model, explore various aspects of the model,\nvalidate it against experiments, and finally verify and demonstrate a numerical\nimplementation.",
        "positive": "Two-dimensional nematics in bulk and confined geometries: Two-dimensional nematics possess peculiar properties that have been studied\nrecently using computer simulation and various theoretical models. Here we\nreview our own contribution to the field using density-functional theory, and\npresent some preliminary simulation results on confined two-dimensional\nnematics. First we discuss the possible stable bulk phases and phase diagrams\nand the relation between phases and particle geometry. We then explore the\nadsorption properties on a single substrate and the confinement effects that\narise when the fluid is confined between parallel walls. Next, confinement in\ncircular cavities is presented; this geometry allows us to measure some\nproperties of the simplest defects that arise in two-dimensional nematics.\nFinally, preliminary Monte Carlo simulation results of confined nematics in\ncircular geometry are shown."
    },
    {
        "anchor": "Thermalization of plastic flow versus stationarity of thermomechanical\n  equilibrium in SGR theory: We discuss issues related to thermalization of plastic flow in the context of\nsoft glassy rheology (SGR) theory. An apparent problem with the theory in its\ncurrent form is that the stationarity of thermomechanical equilibrium obtained\nby requiring that its flow rule satisfy detailed balance in the absence of\napplied deformation requires plastic flow to be athermal. This prevents proper\napplication of SGR to small-molecule and polymer glasses where plastic flow is\noften well-thermalized. Clearly, one would like to have a SGR-like theory of\nthermalized plastic flow that satisfies stationarity. We discuss reasons why\nsuch a theory could prove very useful and clarify obstacles that must be\novercome in order to develop it.",
        "positive": "Thermodynamic anomalies and structural fluctuations in aqueous solutions\n  of tertiary butyl alcohol: In this work, we discuss the connection between the anomalies of the\nthermodynamic properties, experimentally observed in tertiary butyl alcohol\n(TBA) and water solutions, and the molecular clustering in these solutions, as\nrevealed by molecular dynamics (MD) simulations. These anomalies are observed\nin relatively dilute solutions of about 0.03 to 0.08 mole fraction of TBA and\nbecome more pronounced at low temperatures. MD simulations show that these\nsolutions exhibit shortranged (order of 1 nm), shortlived (tens of picoseconds)\n\"micelle-like\" structural fluctuations in the same concentration range. We\nattribute the anomalies in the thermodynamic properties of aqueous TBA\nsolutions to these structural fluctuations on the molecular scale."
    },
    {
        "anchor": "Orientational transitions in symmetric diblock copolymers on rough\n  surfaces: We present a model addressing the orientation transition of symmetric block\ncopolymers such as PS/PMMA on smooth and rough surfaces. The distortion free\nenergy of parallel and perpendicular lamellar phases in contact with a rough\nsolid surface is calculated as function of the surface roughness amplitude and\nwavelength, as well as the polymer lamellar periodicity (molecular weight). We\nfind an analytical expression for the orientation transition. This expression\nis compared and agrees well with recent experiments done with six different\npolymer molecular weights and surface preparations.",
        "positive": "Active dipolar spheroids in shear flow and transverse field: Population\n  splitting, cross-stream migration and orientational pinning: We study the steady-state behavior of active, dipolar, Brownian spheroids in\na planar channel subjected to an imposed Couette flow and an external\ntransverse field, applied in the 'downward' normal-to-flow direction. The\nfield-induced torque on active spheroids (swimmers) is taken to be of magnetic\nform by assuming that they have a permanent magnetic dipole moment, pointing\nalong their self-propulsion (swim) direction. Using a continuum approach, we\nshow that a host of behaviors emerge over the parameter space spanned by the\nparticle aspect ratio, self-propulsion and shear/field strengths, and the\nchannel width. The cross-stream migration of the model swimmers is shown to\ninvolve a regime of linear response (quantified by a linear-response factor) in\nweak fields. For prolate swimmers, the weak-field behavior crosses over to a\nregime of full swimmer migration to the bottom half of the channel in strong\nfields. For oblate swimmers, a counterintuitive regime of reverse migration\narises in intermediate fields, where a macroscopic fraction of swimmers\nreorient and swim to the top channel half at an acute `upward' angle relative\nto the field axis. The diverse behaviors reported here are analyzed based on\nthe shear-induced population splitting (bimodality) of the swim orientation,\ngiving two distinct, oppositely polarized, swimmer subpopulations (albeit very\ndifferently for prolate/oblate swimmers) in each channel half. In strong\nfields, swimmers of both types exhibit net upstream currents relative to the\nlaboratory frame. The onsets of full migration and net upstream current depend\non the aspect ratio, enabling efficient particle separation strategies in\nmicrofluidic setups."
    },
    {
        "anchor": "Ratchet Cellular Automata for Colloids in Dynamic Traps: We numerically investigate the transport of kinks in a ratchet cellular\nautomata geometry for colloids interacting with dynamical traps. We find that\nthermal effects can enhance the transport efficiency in agreement with recent\nexperiments. At high temperatures we observe the creation and annihilation of\nthermally induced kinks that degrade the signal transmission. We consider both\nthe deterministic and stochastic cases and show how the trap geometry can be\nadjusted to switch between these two cases. The operation of the dynamical trap\ngeometry can be achieved with the adjustment of fewer parameters than ratchet\ncellular automata constructed using static traps.",
        "positive": "A soft departure from jamming: the compaction of deformable granular\n  matter under high pressures: The high-pressure compaction of three dimensional granular packings is\nsimulated using a bonded particle model (BPM) to capture linear elastic\ndeformation. In the model, grains are represented by a collection of point\nparticles connected by bonds. A simple multibody interaction is introduced to\ncontrol Poisson's ratio and the arrangement of particles on the surface of a\ngrain is varied to model both high- and low-frictional grains. At low\npressures, the growth in packing fraction and coordination number follow the\nexpected behavior near jamming and exhibit friction dependence. As the pressure\nincreases, deviations from the low-pressure power-law scaling emerge after the\npacking fraction grows by approximately 0.1 and results from simulations with\ndifferent friction coefficients converge. These results are compared to\npredictions from traditional discrete element method simulations which,\ndepending on the definition of packing fraction and coordination number, may\nonly differ by a factor of two. As grains deform under compaction, the average\nvolumetric strain and asphericity, a measure of the change in the shape of\ngrains, are found to grow as power laws and depend heavily on the Poisson's\nratio of the constituent solid. Larger Poisson's ratios are associated with\nless volumetric strain and more asphericity and the apparent power-law exponent\nof the asphericity may vary. The elastic properties of the packed grains are\nalso calculated as a function of packing fraction. In particular, we find the\nPoisson's ratio near jamming is 1/2 but decreases to 1/4 before rising again as\nsystems densify."
    },
    {
        "anchor": "Pressure of a gas of underdamped active dumbbells: The pressure exerted on a wall by a gas at equilibrium does not depend on the\nshape of the confining potential defining the wall. In contrast, it has been\nshown recently [A.P. Solon et al., Nat. Phys. 11, 673 (2015)] that a gas of\noverdamped active particles exerts on a wall a force that depends on the\nconfining potential, resulting in a net force on an asymmetric wall between two\nchambers at equal densities. Here, considering a model of underdamped\nself-propelled dumbbells in two dimensions, we study how the behavior of the\npressure depends on the damping coefficient of the dumbbells, thus exploring\ninertial effects. We find in particular that the force exerted on a moving wall\nbetween two chambers at equal density continuously vanishes at low damping\ncoefficient, and exhibits a complex dependence on the damping coefficient at\nlow density, when collisions are scarce. We further show that this behavior of\nthe pressure can to a significant extent be understood in terms of the\ntrajectories of individual particles close to and in contact with the wall.",
        "positive": "Twist-grain boundary phase characterized by AFM technique: Twist grain boundary (TGB) phases represent liquid crystalline systems with a\nregular array of defects. In our research, we studied a compound with a stable\nTGBC phase and established its structure by various experimental techniques. We\nobserved the surface of the smectic film by AFM microscope and detected a\nperiodic relief. We found that the displacement amplitude is few nanometers\nwith the periodicity about 500 nm. Such periodicity is in accordance with the\nperiodicity of the TGBC blocks rotation estimated by polarizing microscopy. The\nsurface modulation is explained by the deformation of TGBC structure, which is\ncreated on TGBC films. A simplified model interpreting the observed smectic\nsurface displacement to occur as a consequence of rotating TGBC blocks inside\nthe sample is proposed. TGBC blocks deform differently depending on their\norientation with respect to the force acting by the tip of AFM microscope\ncantilever probing the smectic surface."
    },
    {
        "anchor": "Granular Elasticity without the Coulomb Condition: An self-contained elastic theory is derived which accounts both for\nmechanical yield and shear-induced volume dilatancy. Its two essential\ningredients are thermodynamic instability and the dependence of the elastic\nmoduli on compression.",
        "positive": "Role of loop entropy in the force induced melting of DNA hairpin: Dynamics of a single stranded DNA, which can form a hairpin have been studied\nin the constant force ensemble. Using Langevin dynamics simulations, we\nobtained the force-temperature diagram, which differs from the theoretical\nprediction based on the lattice model. Probability analysis of the extreme\nbases of the stem revealed that at high temperature, the hairpin to coil\ntransition is entropy dominated and the loop contributes significantly in its\nopening. However, at low temperature, the transition is force driven and the\nhairpin opens from the stem side. It is shown that the elastic energy plays a\ncrucial role at high force. As a result, the phase diagram differs\nsignificantly with the theoretical prediction."
    },
    {
        "anchor": "Topology and morphology of self-deforming active shells: We present a generic framework for modelling three-dimensional deformable\nshells of active matter that captures the orientational dynamics of the active\nparticles and hydrodynamic interactions on the shell and with the surrounding\nenvironment. We find that the cross-talk between the self-induced flows of\nactive particles and dynamic reshaping of the shell can result in conformations\nthat are tunable by varying the form and magnitude of active stresses. We\nfurther demonstrate and explain how self-induced topological defects in the\nactive layer can direct the morphodynamics of the shell. These findings are\nrelevant to understanding morphological changes during organ development and\nthe design of bio-inspired materials that are capable of self-organisation.",
        "positive": "Single-parameter aging in the weakly nonlinear limit: Physical aging deals with slow property changes over time caused by molecular\nrearrangements. This is relevant for non-crystalline materials like polymers\nand inorganic glasses, both in production and during subsequent use. The\nNarayanaswamy theory from 1971 describes physical aging - an inherently\nnonlinear phenomenon - in terms of a linear convolution integral over the\nso-called material time $\\xi$. The resulting \"Tool-Narayanaswamy (TN)\nformalism\" is generally recognized to provide an excellent description of\nphysical aging for small, but still highly nonlinear temperature variations.\nThe simplest version of the TN formalism is single-parameter aging according to\nwhich the clock rate $d\\xi/dt$ is an exponential function of the property\nmonitored [T. Hecksher et al., J. Chem. Phys. 142, 241103 (2015)]. For\ntemperature jumps starting from thermal equilibrium, this leads to a\nfirst-order differential equation for property monitored, involving a\nsystem-specific function. The present paper shows analytically that the\nsolution to this equation to first order in the temperature variation has a\nuniversal expression in terms of the zeroth-order solution, $R_0(t)$. Numerical\ndata for a binary Lennard-Jones glass former probing the potential energy\nconfirm that, in the weakly nonlinear limit, the theory predicts aging\ncorrectly from $R_0(t)$ (which by the fluctuation-dissipation theorem is the\nnormalized equilibrium potential-energy time-autocorrelation function)."
    },
    {
        "anchor": "Yielding of a Model Glassformer: an Interpretation with an Effective\n  System of Icosahedra: We consider the yielding under simple shear of a binary Lennard-Jones\nglassformer whose super-Arrhenius dynamics are correlated with the formation of\nicosahedral structures. We recast this glassformer as an effective system of\nicosahedra [Pinney et al. J. Chem. Phys. 143 244507 (2015)]. Looking at the\nsmall-strain region of sheared simulations, we observe that shear rates affect\nthe shear localisation behavior particularly at temperatures below the glass\ntransition as defined with a fit to the Vogel-Fulcher-Tamman equation. At\nhigher temperature, shear localisation starts immediately upon shearing for all\nshear rates. At lower temperatures, faster shear rates can result in a delayed\nstart in shear localisation; which begins close to the yield stress. Building\nfrom a previous work which considered steady-state shear [Pinney et al. J.\nChem. Phys. 143 244507 (2016)], we interpret the response to shear and the\nshear localisation in terms of a \\emph{local} effective temperature with our\nsystem of icosahedra. We find that the effective temperatures of the regions\nundergoing shear localisation increase significantly with increasing strain\n(before reaching a steady state plateau).",
        "positive": "Jamming as a random first-order percolation transition: We determine the dimensional dependence of the percolative exponents of the\njamming transition via numerical simulations in four and five spatial\ndimensions. These novel results complement literature ones, and establish\njamming as a mixed first-order percolation transition, with critical exponents\n$\\beta =0$, $\\gamma = 2$, $\\alpha = 0$ and the finite size scaling exponent\n$\\nu^* = 2/d$ for values of the spatial dimension $d \\geq 2$. We argue that the\nupper critical dimension is $d_u=2$ and the connectedness length exponent is\n$\\nu =1$."
    },
    {
        "anchor": "Analytical mesoscale modeling of aeolian sand transport: The mesoscale structure of aeolian sand transport determines a variety of\nnatural phenomena studied in planetary and Earth science. We analyze it\ntheoretically beyond the mean-field level, based on the grain-scale transport\nkinetics and splash statistics. A coarse-grained analytical model is proposed\nand verified by numerical simulations resolving individual grain trajectories.\nThe predicted height-resolved sand flux and other important characteristics of\nthe aeolian transport layer agree remarkably well with a comprehensive\ncompilation of field and wind tunnel data, suggesting that the model robustly\ncaptures the essential mesoscale physics. By comparing the saturation length\nwith field data for the minimum sand-dune size, we can reconcile conflicting\nprevious models for this most enigmatic emergent aeolian scale and elucidate\nthe importance of intermittent turbulent wind fluctuations for field\nmeasurements.",
        "positive": "Low temperature phase transformations in 4-cyano-4'-pentylbiphenyl (5CB)\n  filled by multiwalled carbon nanotubes: The effects of multiwalled carbon nanotubes (NTs) on low-temperature phase\ntransformations in 5CB were studied by means of differential scanning\ncalorimetry (DSC), low-temperature photoluminescence and measurements of\nelectrical conductivity. The concentration of NTs was varied within 0-1% wt.\nThe experimental data, obtained for pure 5CB by DSC and measurements of\nphotoluminescence in the heating mode, evidenced the presence of two\ncrystallization processes at T->229 K and T->262 K, which correspond to\nC1a->C1b, and C1b->C2 phase transformations. Increase of temperature T from 10\nK to 229 K provoked the red shift of photoluminescence spectral band that was\nexplained by flattening of 5CB molecule conformation. Moreover, the\nphotoluminescence data allow to conclude that crystallisation at T=229 K\nresults in conformation transition to non-planar 5CB structure characteristic\nto ideal crystal. The non-planar conformations were dominating in nematic\nphase, i.e., at T>297 K. Electrical conductivity data for NTs-5CB composites\nrevealed supplementary anomaly inside the stable crystalline phase C2,\nidentified earlier in the temperature range 229 K-296.8 K. It can reflect the\ninfluence of phase transformation of 5CB in interfacial layers on the transport\nof charge carriers between NTs."
    },
    {
        "anchor": "Adsorption of polymer chains on structured surface: field theoretical\n  approach: Taking into account the well known correspondence between the field\ntheoretical O(n)-vector model in the limit $n\\to 0$ and the behavior of\nlong-flexible polymer chains in a good solvent the investigation of ideal\npolymer chains adsorption onto structured surface like as a chemical step\n(where one part of a surface is repulsive for polymers and other part is at the\nadsorption threshold) was performed. The two-point correlation function of\nideal polymer chain in the half - space bounded by structured surface with\ndifferent adsorption energies $c_{1}$ and $c_{2}$ (with $c_{1}\\neq c_{2}$) and\nthe \"closest form\" for the free propagator of the model were obtained in\nanalytical form. Besides, the force which ideal polymer chain with free end\nexerts on the structured surface, when the other end is fixed at the surface,\nwas calculated. The obtained results indicate that the process of homopolymer\nadsorption onto structured surfaces should be described by different scaling\nlaws than universal scaling laws predicted in the literature for homopolymer\nadsorption on homogeneous surfaces.",
        "positive": "Molecular Mechanism of Gas Solubility in Liquid: Constant Chemical\n  Potential Molecular Dynamics Simulations: Accurate prediction of a gas solubility in a liquid is crucial in many areas\nof chemistry, and a detailed understanding of the molecular mechanism of the\ngas solvation continues to be an active area of research. Here, we extend the\nidea of constant chemical potential molecular dynamics (C{\\mu}MD) approach to\nthe calculation of the gas solubility in the liquid under constant gas chemical\npotential conditions. As a representative example, we utilize this method to\ncalculate the isothermal solubility of carbon dioxide in water. Additionally,\nwe provide microscopic insight into the mechanism of solvation that\npreferentially occurs in areas of the surface where the hydrogen network is\nbroken."
    },
    {
        "anchor": "Slack Dynamics on an Unfurling String: An arch will grow on a rapidly deployed thin string in contact with a rigid\nplane. We present a qualitative model for the growing structure involving the\namplification, rectification, and advection of slack in the presence of a\nsteady stress field, validate our assumptions with numerical experiments, and\npose new questions about the spatially developing motions of thin objects.",
        "positive": "The Expansion in Width for Domain Walls in Nematic Liquid Crystals in\n  External Magnetic Field: The improved expansion in width is applied to curved domain walls in uniaxial\nnematic liquid crystals in external magnetic field. In the present paper we\nconcentrate on the case of equal elastic constants. We obtain approximate form\nof the director field up to second order in magnetic coherence length."
    },
    {
        "anchor": "Effect of polymer concentration and length of hydrophobic end block on\n  the unimer-micelle transition broadness in amphiphilic ABA symmetric triblock\n  copolymer solutions: The effects of the length of each hydrophobic end block N_{st} and polymer\nconcentration \\bar{\\phi}_{P} on the transition broadness in amphiphilic ABA\nsymmetric triblock copolymer solutions are studied using the self-consistent\nfield lattice model. When the system is cooled, micelles are observed, i.e.,the\nhomogenous solution (unimer)-micelle transition occurs. When N_{st} is\nincreased, at fixed \\bar{\\phi}_{P}, micelles occur at higher temperature, and\nthe temperature-dependent range of micellar aggregation and half-width of\nspecific heat peak for unimer-micelle transition increase monotonously.\nCompared with associative polymers, it is found that the magnitude of the\ntransition broadness is determined by the ratio of hydrophobic to hydrophilic\nblocks, instead of chain length. When \\bar{\\phi}_{P} is decreased, given a\nlarge N_{st}, the temperature-dependent range of micellar aggregation and\nhalf-width of specific heat peak initially decease, and then remain nearly\nconstant. It is shown that the transition broadness is concerned with the\nchanges of the relative magnitudes of the eductions of nonstickers and solvents\nfrom micellar cores.",
        "positive": "Topological Floppy Modes in Epithelial Tissues: Recent advances in topological mechanics have revealed unusual phenomena such\nas topologically protected floppy modes and states of self-stress that are\nexponentially localized at boundaries and interfaces of mechanical networks. In\nthis paper, we explore the topological mechanics of epithelial tissues, where\nthe appearance of these boundary and interface modes could lead to localized\nsoft or stressed spots and play a role in morphogenesis. We consider both a\nsimple vertex model (VM) governed by an effective elastic energy and its\ngeneralization to an active tension network (ATN) which incorporates active\nadaptation of the cytoskeleton. By analyzing spatially periodic lattices at the\nMaxwell point of mechanical instability, we find topologically polarized phases\nwith exponential localization of floppy modes and states of self-stress in the\nATN when cells are allowed to become concave, but not in the VM."
    },
    {
        "anchor": "Dynamics and Topology of Flexible Chains: Knots in Steady Shear Flows: We use numerical simulations of a bead-spring model chain to investigate the\nevolution of the conformation of long and flexible elastic fibers in a steady\nshear flow. In particular, for rather open initial configurations, and by\nvarying a dimensionless elastic parameter, we identify two distinct\nconformational modes with different final size, shape, and orientation. Through\nfurther analysis we identify slipknots in the chain. Finally, we provide\nexamples of initial configurations of an \"open\" trefoil knot that the flow\nunknots and then knots again, sometimes repeating several times. These changes\nin topology should be reflected in changes in bulk rheological and/or transport\nproperties.",
        "positive": "De-pinning of contact line of droplets on rough surfaces: The present study reports the formation of self-assembled droplet pattern on\nthe PDMS polymer coated over grooved side of DVD under saturated vapours of\nalcohols. Comparison of the results with breath figures formed over\nunconstrained side of DVD is made. Four different environments namely methanol,\nethanol, 2-propanol and n-butanol are used for the analysis. It is observed\nthat the pattern formation occurs with methanol and ethanol vapours and not\nwith 2-propanol and n-butanol. The difference is pattern formation with\ndifferent alcohols is attributed to the variation in chain length and the\npresence of hydrophobic groups in alcohols, as given by Traube's rule. The\ndistortion of patterns over constrained surface is attributed to the depinning\nof contact lines."
    },
    {
        "anchor": "Time-dependent active microrheology in dilute colloidal suspensions: In a microrheological set-up a single probe particle immersed in a complex\nfluid is exposed to a strong external force driving the system out of\nequilibrium. Here, we elaborate analytically the time-dependent response of a\nprobe particle in a dilute suspension of Brownian particles to a large\nstep-force, exact in first order of the density of the bath particles. The\ntime-dependent drift velocity approaches its stationary state value\nexponentially fast for arbitrarily small driving in striking contrast to the\npower-law prediction of linear response encoded in the long-time tails of the\nvelocity autocorrelation function. We show that the stationary-state behavior\ndepends nonanalytically on the driving force and connect this behavior to the\npersistent correlations in the equilibrium state. We argue that this relation\nholds generically. Furthermore, we elaborate that the fluctuations in the\ndirection of the force display transient superdiffusive behavior.",
        "positive": "Hydrodynamics strongly affect the dynamics of colloidal gelation but not\n  gel structure: Colloidal particles with strong, short-ranged attractions can form a gel. We\nsimulate this process without and with hydrodynamic interactions (HI), using\nthe lattice-Boltzmann method to account for presence of a thermalized solvent.\nWe show that HI speed up and slow down gelation at low and high volume\nfractions, respectively. The transition between these two regimes is linked to\nthe existence of a percolating cluster shortly after quenching the system.\nHowever, when we compare gels at matched 'structural age', we find nearly\nindistinguishable structures with and without HI. Our result explains\nlongstanding, unresolved conflicts in the literature."
    },
    {
        "anchor": "Layer Analysis of the Structure of Water Confined in Vycor Glass: A Molecular Dynamics simulation of the microscopic structure of water\nconfined in a silica pore is presented. A single cavity in the silica glass has\nbeen modeled as to reproduce the main features of the pores of real Vycor\nglass. A layer analysis of the site-site radial distribution functions evidence\nthe presence in the pore of two subsets of water molecules with different\nmicroscopic structure. Molecules which reside in the inner layer, close to the\ncenter of the pore, have the same structure as bulk water but at a temperature\nof 30 K higher. On the contrary the structure of the water molecules in the\nouter layer, close to the substrate, is strongly influenced by the\nwater-substrate hydrophilic interaction and sensible distortions of the H-bond\nnetwork and of the orientational correlations between neighboring molecules\nshow up. Lowering the hydration has little effect on the structure of water in\nthe outer layer. The consequences on experimental determinations of the\nstructural properties of water in confinement are discussed.",
        "positive": "Heterogeneous Force Chains in Cellularized Biopolymer Network: Biopolymer Networks play an important role in coordinating and regulating\ncollective cellular dynamics via a number of signaling pathways. Here, we\ninvestigate the mechanical response of a model biopolymer network due to the\nactive contraction of embedded cells. Specifically, a graph (bond-node) model\nderived from confocal microscopy data is used to represent the network\nmicrostructure, and cell contraction is modeled by applying correlated\ndisplacements at specific nodes, representing the focal adhesion sites. A\nforce-based stochastic relaxation method is employed to obtain force-balanced\nnetwork under cell contraction. We find that the majority of the forces are\ncarried by a small number of heterogeneous force chains emitted from the\ncontracting cells. The force chains consist of fiber segments that either\npossess a high degree of alignment before cell contraction or are aligned due\nto the reorientation induced by cell contraction. Large fluctuations of the\nforces along different force chains are observed. Importantly, the decay of the\nforces along the force chains is significantly slower than the decay of\nradially averaged forces in the system. These results suggest that the fibrous\nnature of biopolymer network structure can support long-range force\ntransmission and thus, long-range mechanical signaling between cells."
    },
    {
        "anchor": "Distribution of contact forces in a homogeneous granular material of\n  identical spheres under triaxial compression: The distribution P(F) of contact forces F in a homogeneous isotropic\ndisordered granular sample subject to uniform triaxial stress field is studied\nusing a model where forces propagate and collide. Collisions occur at grain and\nobey given rules which allow satisfying local static equilibrium. Analogy with\nBoltzmann's equation of density evolution is drawn and used to derive the\nparameters that control the distribution Ps(F) of contact forces F in the\nstationary state in case of a packing of mono-disperse spheres. Using symmetry\nargument and mean field approximation, it is found that stationarity is\nachieved when the density Ps(F) of force can be written as the product of\nexponentials of quantities whose sums are preserved during collisions. This\nintroduces 3 parameters in 2d and 6 in 3d which are the mean force components\n{Fxo, Fyo, Fzo}, and the mean torques of the force on a grain {Mxo, Myo, Mzo}\n>. Astonishingly, it seems that the theory cannot include distribution of\ncontact orientation implicitly. Extension of the model is possible with some\ncare to case of anisotropic packing. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn",
        "positive": "Active Ornstein-Uhlenbeck model for self-propelled particles with\n  inertia: Self-propelled particles, which convert energy into mechanical motion,\nexhibit inertia if they have a macroscopic size or move inside a gaseous\nmedium, in contrast to micron-sized overdamped particles immersed in a viscous\nfluid. Here we study an extension of the active Ornstein-Uhlenbeck model, in\nwhich self-propulsion is described by colored noise, to access these inertial\neffects. We summarize and discuss analytical solutions of the particle's\nmean-squared displacement and velocity autocorrelation function for several\nsettings ranging from a free particle to various external influences, like a\nlinear or harmonic potential and coupling to another particle via a harmonic\nspring. Taking into account the particular role of the initial particle\nvelocity in a nonstationary setup, we observe all dynamical exponents between\nzero and four. After the typical intertial time, determined by the particle's\nmass, the results inherently revert to the behavior of an overdamped particle\nwith the exception of the harmonically confined systems, in which the overall\ndisplacement is enhanced by inertia. We further consider an underdamped model\nfor an active particle with a time-dependent mass, which critically affects the\ndisplacement in the intermediate time-regime. Most strikingly, for a\nsufficiently large rate of mass accumulation, the particle's motion is\ncompletely governed by inertial effects as it remains superdiffusive for all\ntimes."
    },
    {
        "anchor": "The effect of internal architecture on the assembly of soft particles at\n  fluid interfaces: Monolayers of soft colloidal particles confined at fluid interfaces have been\nattracting increasing interest for fundamental studies and applications alike.\nHowever, establishing the relation between their internal architecture, which\nis controlled during synthesis, and their structural and mechanical properties\nupon interfacial confinement, which define the monolayer's properties, remains\nan elusive task. Here, we propose a comprehensive study elucidating this\nrelation for a system of microgels with tunable architecture. We synthesize\ncore-shell microgels, whose soft core can be chemically degraded in a\ncontrolled fashion, yielding particles ranging from analogues of standard\nbatch-synthesized to completely hollow microgels after total core removal. We\ncharacterize the internal structure of these particles, their swelling\nproperties in bulk and their morphologies upon adsorption at an oil-water\ninterface via a combination of numerical simulations and complementary\nexperiments. In particular, we confirm that hollow microgels are mechanically\nstable in bulk aqueous conditions and that the progressive removal of the core\nleads to a significant flattening of the microgels, which become disk-like\nparticles, at the interface. At low compression, the mechanical response of the\nmonolayer is dominated by the presence of loosely crosslinked polymers forming\na corona surrounding the particle within the interfacial plane, regardless of\nthe presence of a core. By contrast, at high compression, the absence of a core\nenables the particles to deform in the direction orthogonal to the interface.\nThese findings shed new light on which structural features of soft particles\ndetermine their interfacial behaviour, enabling new design strategies for\ntailored materials.",
        "positive": "Propagating stress-pulses and wiggling transition revealed in string\n  dynamics: Understanding string dynamics yields insights into the intricate dynamic\nbehaviors of various filamentary thin structures in nature and industry\ncovering multiple length scales. In this work, we investigate the planar\ndynamics of a flexible string where one end is free and the other end is\nsubject to transverse and longitudinal motions. Under transverse harmonic\nmotion, we reveal the propagating pulse structure in the stress profile over\nthe string, and analyze its role in bringing the system into a chaotic state.\nFor a string where one end is under longitudinal uniform acceleration, we\nidentify the wiggling transition, derive the analytical wiggling solution from\nthe string equations, and present the phase diagram."
    },
    {
        "anchor": "Motion of nanodroplets near chemical heterogeneities: We investigate the dynamics of nanoscale droplets in the vicinity of chemical\nsteps which separate parts of a substrate with different wettabilities. Due to\nlong-ranged dispersion forces, nanodroplets positioned on one side of the step\nperceive the different character of the other side even at some distances from\nthe step, leading to a dynamic response. The direction of the ensuing motion of\nsuch droplets does not only depend on the difference between the equilibrium\ncontact angles on these two parts but in particular on the difference between\nthe corresponding Hamaker constants. Therefore the motion is not necessarily\ndirected towards the more wettable side and can also be different from that of\ndroplets which span the step.",
        "positive": "Long DNA molecule as a pseudoscalar liquid crystal: We show that a long DNA molecule can form a novel condensed phase of matter,\nthe pseudoscalar liquid crystal, that consists of aperiodically ordered DNA\nfragments in right-handed B and left-handed Z forms. We discuss the possibility\nof transformation of B-DNA into Z-DNA and vice versa via first-order phase\ntransitions as well as transformations from the phase with zero total chirality\ninto pure B- or Z-DNA samples through second-order phase transitions. The\npresented minimalistic phenomenological model describes the pseudoscalar liquid\ncrystal phase of DNA and the phase transition phenomena. We point out to a\npossibility that a pseudoscalar liquid nano-crystal can be assembled via\nDNA-programming."
    },
    {
        "anchor": "Probing the membrane potential of living cells by dielectric\n  spectroscopy: In this paper we demonstrate a quantitative way to measure the membrane\npotential of live cells by dielectric spectroscopy. We also show that the\nvalues of the membrane potential obtained using our technique are in good\nagreement with those obtained using traditional methods-voltage sensitive dyes.\nThe membrane potential is determined by fitting the experimental dielectric\ndispersion curves with the dispersion curves obtain from a theoretical model.\nVariations in the membrane potential were induced by modifying the\nconcentration of potassium chloride in the solution of the cell suspension in\nthe presence of valinomycin. For exemplification of the method, E. coli were\nchosen for our experiments.",
        "positive": "Slow and fast particles in shear-driven jamming: critical behavior and\n  finite size scaling: We do shear-driven simulations of a simple model of non-Brownian particles in\ntwo dimensions. By examining the velocity distribution at different densities\nand shear rates we find strong evidence for the existence of two different\nprocesses, respectively dominated by the slower and the faster particles -- the\nslow process and the fast process. The leading divergence in the shear\nviscosity is governed by the fast process. An examination of height and\nposition of the low-velocity peak in the distribution demonstrates that it is\nthe slow process that is responsible for the correction-to-scaling term in the\ncritical scaling analysis. We further find that the long range velocity\ncorrelations are primarily due to the slow process which implies that the\ndiverging viscosity and the diverging correlation length are only indirectly\nrelated."
    },
    {
        "anchor": "Anisotropic micro-cloths fabricated from DNA-stabilized carbon\n  nanotubes: one-stop manufacturing with electrode needles: Among a variety of solution-based approaches to fabricate anisotropic films\nof aligned carbon nanotubes (CNTs), we focus on the dielectrophoretic assembly\nmethod using AC electric fields in DNA-stabilized CNT suspensions. We\ndemonstrate that a one-stop manufacturing system using electrode needles can\ndraw anisotropic DNA-CNT hybrid films of 10-100 $\\mu$m in size (i.e.,\nfree-standing DNA-CNT micro-cloths) from the remaining suspension into the\natmosphere while maintaining structural order. It has been found that a maximal\ndegree of polarization (ca. 40 \\%) can be achieved by micro-cloths fabricated\nfrom a variety of DNA-CNT mixtures. Our results suggest that the one-stop\nmethod can impart biocompatibility to the downsized CNT films and that the\nDNA-stabilized CNT micro-cloths directly connected to an electrode could be\nuseful for biofuel cells in terms of electron transfer and/or enzymatic\nactivity.",
        "positive": "Like-charge attraction at short distances in a charge-asymmetric\n  two-dimensional two-component plasma: Exact results: We determine exactly the short-distance effective potential between two\n\"guest\" charges immersed in a two-dimensional two-component charge-asymmetric\nplasma composed of positively ($q_1 = +1$) and negatively ($q_2 = -1/2$)\ncharged point particles. The result is valid over the whole regime of\nstability, where the Coulombic coupling (dimensionless inverse temperature)\n$\\beta <4$. At high Coulombic coupling $\\beta>2$, this model features\nlike-charge attraction. Also, there cannot be repulsion between\nopposite-charges at short-distances, at variance with large-distance\ninteractions."
    },
    {
        "anchor": "DNA uptake into nuclei: Numerical and analytical results: The dynamics of polymer translocation through a pore has been the subject of\nrecent theoretical and experimental works. We have considered theoretical\nestimates and performed computer simulations to understand the mechanism of DNA\nuptake into the cell nucleus, a phenomenon experimentally investigated by\nattaching a small bead to the free end of the double helix and pulling this\nbead with the help of an optical trap. The experiments show that the uptake is\nmonotonous and slows down when the remaining DNA segment becomes very short.\nNumerical and analytical studies of the entropic repulsion between the DNA\nfilament and the membrane wall suggest a new interpretation of the experimental\nobservations. Our results indicate that the repulsion monotonically decreases\nas the uptake progresses. Thus, the DNA is pulled in (i) either by a small\nforce of unknown origin, and then the slowing down can be interpreted only\nstatistically; (ii) or by a strong but slow ratchet mechanism, which would\nnaturally explain the observed monotonicity, but then the slowing down requires\nadditional explanations. Only further experiments can unambiguously distinguish\nbetween these two mechanisms.",
        "positive": "Drop dynamics on Liquid Infused Surfaces: The Role of the Wetting Ridge: We employ a free energy lattice Boltzmann method to study the dynamics of a\nternary fluid system consisting of a liquid drop driven by a body force across\na regularly textured substrate, infused by a lubricating liquid. We focus on\nthe case of partial wetting lubricants and observe a rich interplay between\ncontact line pinning and viscous dissipation at the lubricant ridge, which\nbecome dominant at large and small apparent angles respectively. Our numerical\ninvestigations further demonstrate that the relative importance of viscous\ndissipation at the lubricant ridge depends on the drop to lubricant viscosity\nratio, as well as on the shape of the wetting ridge."
    },
    {
        "anchor": "Counterion Effects on Nano-confined Metal-Drug-DNA Complexes: We have explored morphology of DNA molecules bound with Cu-complexes of\npiroxicam molecules, a non-steroidal anti-inflammatory drug (NSAID), under\none-dimensional confinement of thin films and have studied the effect of\ncounterions present in a buffer. X-ray reflectivity at and away from the Cu K\nabsorption edge and atomic force microscopy studies reveal that confinement\nsegregates the drug molecules preferentially in a top layer of the DNA film,\nand counterions enhance this segregation.",
        "positive": "Combining (Non-) Linear Optical and Fluorescence Analysis of DiD to\n  Enhance Lipid Phase Recognition: The widespread interest in phase recognition of lipid membranes has led to\nthe use of different optical techniques to enable differentiation of healthy\nand not fully functional cells. In this work, we show how the combination of\ndifferent (non)linear optical methods such as One Photon Absorption (OPA), Two\nPhoton Absorption (TPA) and Second Harmonic Generation (SHG) as well as the\nstudy of the fluorescence decay time leads to an enhanced screening of membrane\nphases using a fluorescent dioctadecyltetramethylindocarbocyanine (DiD) probe.\nIn the current study we consider the pure liquid disordered phases of DOPC\n(room temperature) and DPPC (323 K), the solid gel phase of DPPC (298 K), and\nthe liquid ordered phase of a 2:1 binary mixture of Sphingomyelin and\nCholesterol. By means of extensive hybrid quantum mechanics molecular mechanics\ncalculations and based upon the (non) linear absorption of the embedded probes,\nit is found that DiD can be used to identify the lipid bilayer phase. The joint\nTPA and SHG as well as fluorescence analyses qualifies DiD as versatile probe\nfor phase recognition. In particular, the SHG data obtained by means of\nHyperRayleigh Scattering and by Electric Field Induced Second Harmonic\nGeneration reveal differences in polarization of the probe in the different\nenvironments. The TPA results finally confirm the particular location of the\nprobe in between the polar head group region of the 2:1 SM:Chol mixture in the\nliquid ordered phase."
    },
    {
        "anchor": "Identification of local structures in water from supercooled to ambient\n  conditions: Studies of water thermodynamics have long been tied to the identification of\ntwo distinct families of local structures, whose competition could explain the\norigin of the many thermodynamic anomalies and of the hypothesized\nliquid-liquid critical point in water. Despite the many successes and insights\ngained, the structural indicators proposed throughout the years were not able\nto unequivocally identify these two families over a wide range of conditions.\nWe show that a recently introduced indicator, $\\Psi$, which exploits\ninformation on the HB network connectivity, can reliably identify these two\ndistinct local environments over a wide range of thermodynamic conditions (188\nto 300 K and 0 to 13 kbar), and that close to the liquid-liquid critical point\nthe spatial correlations of density fluctuations are identical to those of the\n$\\Psi$ indicator. Our results strongly support the idea that water\nthermodynamic properties arise from the competition between two distinct and\nidentifiable local environments.",
        "positive": "Dynamical Ordering of Driven Stripe Phases in Quenched Disorder: We examine the dynamics and stripe formation in a system with competing short\nand long range interactions in the presence of both an applied dc drive and\nquenched disorder. Without disorder, the system forms stripes organized in a\nlabyrinth state. We find that, when the disorder strength exceeds a critical\nvalue, an applied dc drive can induce a dynamical stripe ordering transition to\na state that is more ordered than the originating undriven, unpinned pattern.\nWe show that signatures in the structure factor and transport properties\ncorrespond to this dynamical reordering transition, and we present the dynamic\nphase diagram as a function of strengths of disorder and dc drive."
    },
    {
        "anchor": "Remarks on the n=1/2 disclination line in Landau-de Gennes theory of\n  nematic liquid crystals: Using Landau-de Gennes effective theory for nematic liquid crystals we\nanalyse the structure of rectilinear n=1/2 smooth disclination line in the case\nof equal elastic constants. We find that at certain temperature there is an\nexact mathematical correspondence with a rectilinear vortex in superfluid\n$^4He$. With a help of polynomial approximation difference of free energies of\nthe smooth and of a singular disclination lines is estimated. It turns out that\nthe smooth disclination line is energetically preferred only if temperature is\nlow enough. At higher temperatures a disordered core should be expected.",
        "positive": "Influence of sample inhomogeneity on the linear elongational viscosities\n  of two low density polyethylenes: An experimental investigation of the impact of sample inhomogeneity on\nmeasurements of the linear elongational viscosity of two low-density\npolyethelenes is presented. A novel method of in-situ measurements of the\ndiameter of samples under extension has recently been implemented to properly\naccount for the sample non-uniformities during elongation. Two types of low\ndensity polyethylenes (LDPE's) have been investigated: Lupolen 1840 D and LPDE\n1840 H. Whereas in the case of Lupolen 1840 H the Trouton relationship is\nverified, in the case of Lupolen 1840 D the deviations can be as large as 40%,\ndepending on the magnitude of the initial sample non-uniformity and the\nexperimental conditions. Based on real time visualization of the sample, these\ndeviations are associated with an inhomogeneous deformation of the specimen.\nDifferences in the homogeneity of deformation between the H and D samples are\nexplained by significantly different maximal retardation times. The\nexperimental investigation is complemented by a simplified theoretical\nestimation of the error induced by the sample inhomogeneity in the case of\nmeasurements of elongational viscosities in the linear range. A fair level of\nagreement is found with the experimentally measured error."
    },
    {
        "anchor": "Testing a hypothesis for the evolution of sex: An asexual set of primitive bacteria is simulated with a bit-string Penna\nmodel with a Fermi function for survival. A recent hypothesis by Jan, Stauffer\nand Moseley on the evolution of sex from asexual cells as a strategy for trying\nto escape the effects of deleterious mutations is checked. This strategy is\nfound to provide a successful scenario for the evolution of a stable\nmacroscopic sexual population.",
        "positive": "Tension-induced multistability in inextensible helical ribbons: We study the non-monotonic force-extension behaviour of helical ribbons using\na new model for inextensible elastic strips. Unlike previous rod models our\nmodel predicts hysteresis behaviour for low-pitch ribbons of arbitrary material\nproperties. Associated with it is a first-order transition between two\ndifferent helical states as observed in experiments with cholesterol ribbons.\nNumerical solutions show non-uniform uncoiling with hysteresis also occurring\nunder controlled tension. They furthermore reveal a new uncoiling scenario in\nwhich a ribbon of very low pitch shears under tension and successively releases\na sequence of almost planar loops. Our results may be relevant for nanoscale\ndevices such as force probes."
    },
    {
        "anchor": "Nucleation at the contact line observed on nano-textured surfaces: It has been conjectured that roughness plays a role in surface nucleation,\nthe tendency for freezing to begin preferentially at the liquid-gas interface.\nUsing high speed imaging, we sought evidence for freezing at the contact line\non catalyst substrates with imposed characteristic length scales (texture).\nLength scales consistent with the critical nucleus size and with $\\delta \\sim\n\\tau / \\sigma$, where $\\tau$ is a relevant line tension and $\\sigma$ is the\nsurface tension, range from nanometers to micron. It is found that nano-scale\ntexture causes a shift in the nucleation of ice in supercooled water to the\nthree-phase contact line, while micro-scale texture does not.",
        "positive": "Magnetic Soret effect: Application of the ferrofluid dynamics theory: The ferrofluid dynamics theory is applied to thermodiffusive problems in\nmagnetic fluids in the presence of magnetic fields. The analytical form for the\nmagnetic part of the chemical potential and the most general expression of the\nmass flux are given. By employing these results to experiments, global Soret\ncoefficients in agreement with measurements are determined. Also an estimate\nfor a hitherto unknown transport coefficient is made."
    },
    {
        "anchor": "Stretching of a fractal polymer around a disc reveals KPZ-like\n  statistics: While stretching of a polymer along a flat surface is hardly different from\nthe classical Pincus problem of pulling chain ends in free space, the role of\ncurved geometry in conformational statistics of the stretched chain is an\nexciting open question. Here by means of the scaling analyses and computer\nsimulations we examine stretching of a fractal polymer chain around a disc in\n2D (or a cylinder in 3D) of radius $R$. Surprisingly, we reveal that the\ntypical excursions of the polymer away from the surface scale as $\\Delta \\sim\nR^{\\beta}$, with the Kardar-Parisi-Zhang (KPZ) growth exponent $\\beta=1/3$, for\nany fractal dimension of the chain. Moreover, we find that the\ncurvature-induced correlation length of a fractal chain behaves as $S^* \\sim\nR^{1/z}$ with the KPZ dynamic exponent $z=3/2$, suggesting that the crossover\nfrom flat to curved geometry of a stretched polymer corresponds to the\ncrossover from large to short time scales in the KPZ stochastic growth. Thus,\nwe argue that curvature of an underlying boundary furnishes universal KPZ-like\nstatistics to the stretched fractal paths, which further suggests numerous\nconnections with several branches of mathematical physics.",
        "positive": "Minimal cyclic behavior in sheared amorphous solids: Although jammed packings of soft spheres exist in potential-energy landscapes\nwith a vast number of minima, when subjected to cyclic shear they may revisit\nthe same configurations repeatedly. Simple hysteretic spin models, in which\nparticle rearrangements are represented by spin flips, capture many features of\nthis periodic behavior. Yet it has been unclear to what extent individual\nrearrangements can be described by such binary objects. Using a particularly\nsensitive algorithm, we identify rearrangements in simulated jammed packings.\nWe select pairs of rearrangements that undo one another to create periodic\ncyclic behavior, explore the statistics of these pairs, and show that their\ninternal structure is more complex than a spin analogy would indicate. This\noffers insight into both the collective nature of rearrangement events\nthemselves and how complex systems such as amorphous solids can reach a limit\ncycle with relative ease."
    },
    {
        "anchor": "Recent theoretical advances in elasticity of membranes following\n  Helfrich's spontaneous curvature model: Recent theoretical advances in elasticity of membranes following Helfrich's\nfamous spontaneous curvature model are summarized in this review. The governing\nequations describing equilibrium configurations of lipid vesicles, lipid\nmembranes with free edges, and chiral lipid membranes are presented. Several\nanalytic solutions to these equations and their corresponding configurations\nare demonstrated.",
        "positive": "Forming Three-Dimensional Colloidal Structures Using Holographic Optical\n  Tweezers: A method for forming permanent three dimensional structures from colloidal\nparticles using holographic optical trapping is described. Holographic optical\ntweezers (HOT) are used to selectively position charge stabilized colloidal\nparticles within a flow cell. Once the particles are in the desired location an\nelectrolyte solution is pumped into the cell which reduces the Debye length and\ninduces aggregation caused by the van der Waals attraction. This technique\nallows for the formation of three dimensional structures both on and away from\nthe substrate that can be removed from solution without the aid of critical\npoint drying. This technique is inexpensive, fast, and versatile as it relies\non forces acting on almost all colloidal suspensions."
    },
    {
        "anchor": "Diffusion and Current of Brownian Particles in Tilted Piecewise Linear\n  Potentials: Amplification and Coherence: Overdamped motion of Brownian particles in tilted piecewise linear periodic\npotentials is considered. Explicit algebraic expressions for the diffusion\ncoefficient, current, and coherence level of Brownian transport are derived.\nTheir dependencies on temperature, tilting force, and the shape of the\npotential are analyzed. The necessary and sufficient conditions for the\nnon-monotonic behavior of the diffusion coefficient as a function of\ntemperature are determined. The diffusion coefficient and coherence level are\nfound to be extremely sensitive to the asymmetry of the potential. It is\nestablished that at the values of the external force, for which the enhancement\nof diffusion is most rapid, the level of coherence has a wide plateau at low\ntemperatures with the value of the Peclet factor 2. An interpretation of the\namplification of diffusion in comparison with free thermal diffusion in terms\nof probability distribution is proposed.",
        "positive": "Successive Phase Transitions in Antiferroelectric Liquid Crystal Systems: An axial next-nearest-neighbor XY model is studied as a model of chiral\nliquid crystals which exhibit many ferro-, ferri- and antiferroelectric tilted\nsmectic phases. Depending on the values of interaction parameters, this model\nexhibits Ising symmetric (i.e., the tilt directions of directors are parallel\nor anti parallel) phases or XY symmetric phases. Phases with each\ntype-of-symmetry show the character of devil's staircase, which has been\nobserved in experiments."
    },
    {
        "anchor": "Immobilization of a bubble in water by nanoelectrolysis: A surprising phenomenon is presented: a bubble, produced from water\nelectrolysis, is immobilized in the liquid (as if the Archimedes' buoyant force\nwere annihilated). This is achieved using a nanoelectrode (1 nm to 1 $\\mu$m of\ncurvature radius at the apex) and an alternating electric potential with\nadapted values of amplitude and frequency. A simple model based on\n\"nanoelectrolysis\" (i.e., nanolocalization of the production of H2 and O2\nmolecules at the apex of the nanoelectrode) and an \"open bubble\" (i.e.,\nexchanging H2 and O2 molecules with the solution) explains most of the\nobservations.",
        "positive": "Diffusion Spreadability as a Probe of the Microstructure of Complex\n  Media Across Length Scales: Consider the time-dependent problem of mass transfer of a solute between two\nphases and assume that the solute is initially distributed in one phase (phase\n2) and absent from the other (phase 1). We desire the fraction of total solute\npresent in phase 1 as a function of time, ${\\cal S}(t)$, which we call the {\\it\nspreadability}, since it is a measure of the spreadability of diffusion\ninformation as a function of time. We derive exact direct-space formulas for\n${\\cal S}(t)$ in any Euclidean space dimension $d$ in terms of the\nautocovariance function as well as corresponding Fourier representations of\n${\\cal S}(t)$ in terms of the spectral density. We derive closed-form general\nformulas for the short- and long-time behaviors of the spreadability in terms\nof crucial small- and large-scale microstructural information, respectively.\nThe long-time behavior of ${\\cal S}(t)$ enables one to distinguish the entire\nspectrum of microstructures that span from hyperuniform to nonhyperuniform\nmedia. For hyperuniform media, disordered or not, we show that the \"excess\"\nspreadability, ${\\cal S}(\\infty)-{\\cal S}(t)$, decays to its long-time behavior\nexponentially faster than that of any nonhyperuniform two-phase medium, the\n\"slowest\" being antihyperuniform media. The stealthy hyperuniform class is\ncharacterized by an excess spreadability with the fastest decay rate among all\ntranslationally invariant microstructures. Moreover, we establish a remarkable\nconnection between the spreadability and an outstanding problem in discrete\ngeometry, namely, microstructures with \"fast\" spreadabilities are also those\nthat can be derived from efficient \"coverings\" of space. We also identify\nheretofore unnoticed remarkable links between the spreadability ${\\cal S}(t)$\nand NMR pulsed field gradient spin-echo amplitude as well as diffusion MRI\nmeasurements."
    },
    {
        "anchor": "Thermodynamics of surface tension: application to electrolyte solution: In this contribution to the special issue of the Journal of Statistical\nPhysics dedicated to Michael Fisher on his 70'th birthday, I shall review two\nthermodynamically distinct routes for obtaining the interfacial tension of\nliquid-vapor interfaces in mixtures. A specific application to the calculation\nof the excess surface tension of aqueous electrolyte solutions will be\npresented.",
        "positive": "Facilitation of polymer looping and giant polymer diffusivity in crowded\n  solutions of active particles: We study the dynamics of polymer chains in a bath of self-propelled particles\n(SPP) by extensive Langevin dynamics simulations in a two dimensional system.\nSpecifically, we analyse the polymer looping properties versus the SPP activity\nand investigate how the presence of the active particles alters the chain\nconformational statistics. We find that SPPs tend to extend flexible polymer\nchains while they rather compactify stiffer semiflexible polymers, in agreement\nwith previous results. Here we show that larger activities of SPPs yield a\nhigher effective temperature of the bath and thus facilitate looping kinetics\nof a passive polymer chain. We explicitly compute the looping probability and\nlooping time in a wide range of the model parameters. We also analyse the\nmotion of a monomeric tracer particle and the polymer's centre of mass in the\npresence of the active particles in terms of the time averaged mean squared\ndisplacement, revealing a giant diffusivity enhancement for the polymer chain\nvia SPP pooling. Our results are applicable to rationalising the dimensions and\nlooping kinetics of biopolymers at constantly fluctuating and often actively\ndriven conditions inside biological cells or suspensions of active colloidal\nparticles or bacteria cells."
    },
    {
        "anchor": "Compaction of mixtures of rigid and highly deformable particles: a\n  micro-mechanical model: We analyze the isotropic compaction of mixtures composed of rigid and\ndeformable incompressible particles by the non-smooth contact dynamics approach\n(NSCD). The deformable bodies are simulated using a hyper-elastic neo-Hookean\nconstitutive law by means of classical finite elements. For mixtures that\nvaried from totally rigid to totally deformable particles, we characterize the\nevolution of the packing fraction, the elastic modulus, and the connectivity as\na function of the applied stresses when varying inter-particle coefficient of\nfriction. We show first that the packing fraction increases and tends\nasymptotically to a maximum value $\\phi_{max}$, which depends on both the\nmixture ratio and the inter-particle friction. The bulk modulus is also shown\nto increase with the packing fraction and to diverges as it approaches\n$\\phi_{max}$. From the micro-mechanical expression of the granular stress\ntensor, we develop a model to describe the compaction behavior as a function of\nthe applied pressure, the Young modulus of the deformable particles, and the\nmixture ratio. A bulk equation is also derived from the compaction equation.\nThis model lays on the characterization of a single deformable particle under\ncompression together with a power-law relation between connectivity and packing\nfraction. This compaction model, set by well-defined physical quantities,\nresults in outstanding predictions from the jamming point up to very high\ndensities and allows us to give a direct prediction of $\\phi_{max}$ as a\nfunction of both the mixture ratio and the friction coefficient.",
        "positive": "Statics and Dynamics of Yukawa Cluster Crystals on Ordered Substrates: We examine the statics and dynamics of particles with repulsive Yukawa\ninteractions in the presence of a two-dimensional triangular substrate for\nfillings of up to twelve particles per potential minimum. We term the ordered\nstates Yukawa cluster crystals and show that they are distinct from the\ncolloidal molecular crystal states found at low fillings. As a function of\nsubstrate and interaction strength at fixed particle density we find a series\nof novel crystalline states that we characterize using the structure factor.\nFor fillings greater than four, shell and ring structures form at each\npotential minimum and can exhibit sample-wide orientational order. A disordered\nstate can appear between ordered states as the substrate strength varies. Under\nan external drive, the onsets of different orderings produce clear changes in\nthe critical depinning force, including a peak effect phenomenon that has\ngenerally only previously been observed in systems with random substrates. We\nalso find a rich variety of dynamic ordering transitions that can be observed\nvia changes in the structure factor and features in the velocity-force curves.\nThe dynamical states encompass a variety of moving structures including\none-dimensional stripes, smectic ordering, polycrystalline states, triangular\nlattices, and symmetry locking states. Despite the complexity of the system, we\nidentify several generic features of the dynamical phase transitions which we\nmap out in a series of phase diagrams. Our results have implications for the\nstructure and depinning of colloids on periodic substrates, vortices in\nsuperconductors and Bose-Einstein condensates, Wigner crystals, and dusty\nplasmas."
    },
    {
        "anchor": "Models of gemini surfactants: Gemini (dimeric) surfactants are composed of two monomeric surfactant\nmolecules linked by a spacer chain. Their self-assembly behavior differs\nqualitatively from that of monomeric surfactants. We review the various\ntheoretical attempts to account for the behavior of this new class of\namphiphilic molecules.",
        "positive": "Diffusiophoretically induced interactions between chemically active and\n  inert particles: In the presence of a chemically active particle, a nearby chemically inert\nparticle can respond to a concentration gradient and move by diffusiophoresis.\nThe nature of the motion is studied for two cases: first, a fixed reactive\nsphere and a moving inert sphere, and second, freely moving reactive and inert\nspheres. The continuum reaction-diffusion and Stokes equations are solved\nanalytically for these systems and microscopic simulations of the dynamics are\ncarried out. Although the relative velocities of the spheres are very similar\nin the two systems, the local and global structures of streamlines and the flow\nvelocity fields are found to be quite different. For freely moving spheres,\nwhen the two spheres approach each other the flow generated by the inert sphere\nthrough diffu- siophoresis drags the reactive sphere towards it. This leads to\na self-assembled dimer motor that is able to propel itself in solution. The\nfluid flow field at the moment of dimer formation changes direction. The ratio\nof sphere sizes in the dimer influences the characteristics of the flow fields,\nand this feature suggests that active self-assembly of spherical colloidal\nparticles may be manipulated by sphere-size changes in such reactive systems."
    },
    {
        "anchor": "The potential energy landscape and inherent dynamics of a hard-sphere\n  fluid: Hard-sphere models exhibit many of the same kinds of supercooled-liquid\nbehavior as more realistic models of liquids, but the highly non-analytic\ncharacter of their potentials makes it a challenge to think of that behavior in\npotential-energy-landscape terms. We show here that it is possible to calculate\nan important topological property of hard-sphere landscapes, the geodesic\npathways through those landscapes, and to do so without artificially\ncoarse-graining or softening the potential. We show, moreover, that the rapid\ngrowth of the lengths of those pathways with increasing packing fraction\nquantitatively predicts the precipitous decline in diffusion constants in a\nglass-forming hard-sphere mixture model. The geodesic paths themselves can be\nconsidered as defining the intrinsic dynamics of hard spheres, so it is also\nrevealing to find that they (and therefore the features of the underlying\npotential-energy landscape) correctly predict the occurrence of dynamic\nheterogeneity and non-zero values of the non-Gaussian parameter. The success of\nthese landscape predictions for the dynamics of such a singular model\nemphasizes that there is more to potential energy landscapes than is revealed\nby looking at the minima and saddle points.",
        "positive": "Universal mechanical instabilities in the energy landscape of amorphous\n  solids: evidence from athermal quasistatic expansion: Using numerical simulations, we study the failure of an amorphous solid under\nquasi-static expansion starting from a homogeneous high-density state. During\nthe volume expansion, we demonstrate the existence of instabilities manifesting\nvia saddle-node bifurcation in which a minimum meets a saddle. During all such\nevents, the smallest eigenvalue of the Hessian matrix vanishes as a square-root\nsingularity. The plastic instabilities are manifested via sudden jumps in\npressure and energy, with the largest event happening when a cavity appears,\nleading to the yielding of the material. We show that during cavitation and\nprior to complete fracture, the statistics of pressure or energy jumps\ncorresponding to the plastic events show sub-extensive finite-size scaling,\nsimilar to the case of simple shear but with different exponents. Thus,\noverall, our study reveals universality in the fundamental characteristics\nduring mechanical failure in amorphous solids under any quasi-static\ndeformation protocol."
    },
    {
        "anchor": "Cooling-rate dependence of kinetic and mechanical stability of simulated\n  glasses: Recently, ultrastable glasses have been created through vapor deposition.\nSubsequently, computer simulation algorithms have been proposed that mimic the\nvapor deposition process and result in simulated glasses with increased\nstability. In addition, random pinning has been used to generate very stable\nglassy configurations without the need for lengthy annealing or special\nalgorithms inspired by vapor deposition. Kinetic and mechanical stability of\nexperimental ultrastable glasses is compared to those of experimental glasses\nformed by cooling. We provide the basis for a similar comparison for simulated\nstable glasses: we analyze the kinetic and mechanical stability of simulated\nglasses formed by cooling at a constant rate by examining the transformation\ntime to a liquid upon rapid re-heating, the inherent structure energies, and\nthe shear modulus. The kinetic and structural stability increases slowly with\ndecreasing cooling rate. The methods outlined here can be used to assess\nkinetic and mechanical stability of simulated glasses generated by using\nspecialized algorithms.",
        "positive": "Jet impact on a soap film: We experimentally investigate the impact of a liquid jet on a soap film. We\nobserve that the jet never breaks the film and that two qualitatively different\nsteady regimes may occur. The first one is a refraction-like behavior obtained\nat small incidence angles when the jet crosses the film and is deflected by the\nfilm-jet interaction. For larger incidence angles, the jet is absorbed by the\nfilm, giving rise to a new class of flow in which the jet undulates along the\nfilm with a characteristic wavelength. Besides its fundamental interest, this\nstudy presents a new way to guide a micro-metric flow of liquid in the inertial\nregime and to probe foam stability submitted to violent perturbations at the\nsoap film scale."
    },
    {
        "anchor": "Anomalous coupling between topological defects and curvature: We investigate a counterintuitive geometric interaction between defects and\ncurvature in thin layers of superfluids, superconductors and liquid crystals\ndeposited on curved surfaces. Each defect feels a geometric potential whose\nfunctional form is determined only by the shape of the surface, but whose sign\nand strength depend on the transformation properties of the order parameter.\nFor superfluids and superconductors, the strength of this interaction is\nproportional to the square of the charge and causes all defects to be repelled\n(attracted) by regions of positive (negative) Gaussian curvature. For liquid\ncrystals in the one elastic constant approximation, charges between 0 and\n$4\\pi$ are attracted by regions of positive curvature while all other charges\nare repelled.",
        "positive": "Short-time dynamics of random-bond Potts ferromagnet with continuous\n  self-dual quenched disorders: We present Monte Carlo simulation results of random-bond Potts ferromagnet\nwith the Olson-Young self-dual distribution of quenched disorders in\ntwo-dimensions. By exploring the short-time scaling dynamics, we find universal\npower-law critical behavior of the magnetization and Binder cumulant at the\ncritical point, and thus obtain estimates of the dynamic exponent $z$ and\nmagnetic exponent $\\eta$, as well as the exponent $\\theta$. Our special\nattention is paid to the dynamic process for the $q$=8 Potts model."
    },
    {
        "anchor": "Active fluctuations in the harmonic chain: phonons, entropons and\n  velocity correlations: Non-equilibrium random fluctuations of non-thermal nature are a salient\nfeature of active matter. In this work, we consider the collective excitations\nof active systems at high density, focusing on a one-dimensional chain of\nelastically coupled inertial particles, whose activity is modeled with an\nOrnstein-Uhlenbeck process. Their excitation spectrum shows the presence of two\nkinds of fluctuations: the first ones are thermally excited phonons analogous\nto those of a passive crystal while the second ones have been termed entropons\nbecause associated with the entropy production due to the active forces. These\ntwo types of fluctuations show different properties: in fact, only entropons\ngenerate spatial velocity correlations and fail to satisfy a standard\nfluctuation-response relation. We derive the exact expression for the\nequal-time velocity and displacement correlations as well as for the structure\nfactor and in each case identify the phonon and entropon contributions.\nFinally, we investigate the dynamical properties of the excitations in terms of\nsteady-state two-time correlations, such as the intermediate scattering\nfunction and the mean-square displacement, and show that both phonon and\nentropon fluctuations are characterized by a long wavelength overdamped regime\nand a short wavelength underdamped regime. In the large persistence case,\nentropons decay slower than phonons, and in general, activity tends to suppress\nthe oscillations typical of the underdamped regime.",
        "positive": "Enhanced phoretic self-propulsion of active colloids through surface\n  charge asymmetry: Charged colloidal particles propel themselves through asymmetric fluxes of\nchemically generated ions on their surface. We show that asymmetry in the\nsurface charge distribution introduces a new mode of self-phoretic motion for\nchemically active particles that produce ionic species. Particles of sizes\nsmaller than or comparable to the Debye length achieve directed self-propulsion\nthrough surface charge asymmetry even when ionic flux is uniform over the\nparticle surface. Janus nanoparticles endowed with both surface charge and\nionic flux asymmetries results in enhanced propulsion speeds of the order of\n$\\mu$m/s or higher. Our work provides a theoretical framework to quantitatively\ndetermine the velocity of asymmetrically charged nanoparticles undergoing ionic\nself-diffusiophoresis, and suggests an avenue for specifying surface properties\nthat optimize and regulate self-propulsion in ionic media."
    },
    {
        "anchor": "Microscale Marangoni Surfers: We apply laser light to induce the asymmetric heating of Janus colloids\nadsorbed at water-oil interfaces and realize active micrometric \"Marangoni\nsurfers\". The coupling of temperature and surfactant concentration gradients\ngenerates Marangoni stresses leading to self-propulsion. Particle velocities\nspan four orders of magnitude, from microns/s to cm/s, depending on laser power\nand surfactant concentration. Experiments are rationalized by finite elements\nsimulations, defining different propulsion regimes relative to the magnitude of\nthe thermal and solutal Marangoni stress components.",
        "positive": "Flashing flexodomains and electroconvection rolls in a nematic liquid\n  crystal: Pattern forming instabilities induced by ultralow frequency sinusoidal\nvoltages were studied in a rod-like nematic liquid crystal by microscopic\nobservations and simultaneous electric current measurements. Two pattern\nmorphologies, electroconvection (EC) and flexodomains (FD), were distinguished;\nboth appearing as time separated flashes within each half period of driving. A\ncorrelation was found between the time instants of the EC flashes and that of\nthe nonlinear current response. The voltage dependence of the pattern contrast\nC(U) for EC has a different character than that for the FD. The flattening of\nC(U) at reducing the frequency was described in terms of an imperfect\nbifurcation model. Analysing the threshold characteristics of FD the\ntemperature dependence of the difference |e_1-e_3| of the flexoelectric\ncoefficients were also determined by considering elastic anisotropy."
    },
    {
        "anchor": "Nanoparticles modulate contact angle hysteresis in electrowetting: The pinning of the contact line adversely influences the electrowetting\nperformance of sessile liquid droplets. In this paper, we report the\nelectrowetting hysteresis characteristics of 100 mM aq. KCl sessile liquid\ndroplet placed on a hydrophobic PDMS surface. The effect of nanoparticles on\nthe contact angle hysteresis under the imposed electric potential is further\ninvestigated. This study reveals that the contact angle hysteresis decreases\nbeyond a certain threshold value of nanoparticles concentration. Therefore,\nnanoparticle suspension in the liquid droplet can be used to enhance or\nsuppress the electrowetting hysteresis and consequentially rate of heat\ntransfer during hot spot cooling.",
        "positive": "Effective interactions, Fermi-Bose duality, and ground states of\n  ultracold atomic vapors in tight de Broglie waveguides: Derivation of effective zero-range one-dimensional (1D) interactions between\natoms in tight waveguides is reviewed, as is the Fermi-Bose mapping method for\ndetermination of exact and strongly-correlated states of ultracold bosonic and\nfermionic atomic vapors in such waveguides, including spin degrees of freedom.\nOdd-wave 1D interactions derived from 3D p-wave scattering are included as well\nas the usual even-wave interactions derived from 3D s-wave scattering, with\nemphasis on the role of 3D Feshbach resonances for selectively enhancing s-wave\nor p-wave interactions. A duality between 1D fermions and bosons with\nzero-range interactions suggested by Cheon and Shigehara is shown to hold for\nthe effective 1D dynamics of a spinor Fermi gas with both even and odd-wave\ninteractions and that of a spinor Bose gas with even and odd-wave interactions,\nwith even(odd)-wave Bose coupling constants inversely related to odd(even)-wave\nFermi coupling constants. Some recent applications of Fermi-Bose mapping to\ndetermination of many-body ground states of Bose gases and of both magnetically\ntrapped, spin-aligned and optically trapped, spin-free Fermi gases are\ndescribed, and a new generalized Fermi-Bose mapping is used to determine the\nphase diagram of ground-state total spin of the spinor Fermi gas as a function\nof the even and odd-wave coupling constants."
    },
    {
        "anchor": "Effective Interactions in Soft Materials: Soft materials, such as colloidal suspensions, polymer solutions, and\nbiological systems, are typically multicomponent mixtures of macromolecules and\nsimpler components (e.g., microions, monomers, solvent) that can assemble into\ncomplex structures spanning broad length and time scales. Many characteristic\ntraits of soft matter, e.g., mechanical fragility, sensitivity to external\ninfluence, and tunable thermal and optical properties, emerge from a mingling\nof microscopic and mesoscopic constituents. Large asymmetries in size and\ncharge between macromolecules and microscopic components often make impractical\nthe explicit modeling of all degrees of freedom over physically significant\nlength and time scales. The complexity often can be reduced, however, by\npre-averaging (coarse-graining) the degrees of freedom of some microscopic\ncomponents, thus mapping the real system onto a simpler model of fewer\ncomponents, but governed by effective interparticle interactions. This chapter\nreviews the statistical mechanical foundations of effective interactions in\nsoft materials and discusses illustrative applications to charged colloids,\npolyelectrolytes, and colloid-polymer mixtures",
        "positive": "Controlling colloidal phase transitions with critical Casimir forces: The critical Casimir effect provides a thermodynamic analogue of the\nwell-known quantum mechanical Casimir effect. It acts between two surfaces\nimmersed in a critical binary liquid mixture, and results from the confinement\nof concentration fluctuations of the solvent. Unlike the quantum mechanical\neffect, the magnitude and range of this attraction can be adjusted with\ntemperature via the solvent correlation length, thus offering new opportunities\nfor the assembly of nano and micron-scale structures. Here, we demonstrate the\nactive assembly control of equilibrium phases using critical Casimir forces. We\nguide colloidal particles into analogues of molecular liquid and solid phases\nvia exquisite control over their interactions. By measuring the critical\nCasimir particle pair potential directly from density fluctuations in the\ncolloidal gas, we obtain insight into liquefaction at small scales: We apply\nthe Van der Waals model of molecular liquefaction and show that the colloidal\ngas-liquid condensation is accurately described by the Van der Waals theory,\neven on the scale of a few particles. These results open up new possibilities\nin the active assembly control of micro and nanostructures."
    },
    {
        "anchor": "Forces on rigid inclusions in elastic media and resulting\n  matrix-mediated interactions: To describe many-particle systems suspended in incompressible\nlow-Reynolds-number fluids, effective hydrodynamic interactions can be\nintroduced. Here, we consider particles embedded in elastic media. The\neffective elastic interactions between spherical particles are calculated\nanalytically, inspired by the approach in the fluid case. Our experiments on\ninteracting magnetic particles confirm the theory. In view of the huge success\nof the method in hydrodynamics, we similarly expect many future applications in\nthe elastic case, e.g. for elastic composite materials.",
        "positive": "Material Line Fluctuations Slaved to Bulk Correlations in\n  Two-Dimensional Turbulence: An analogy is pointed out between a polymer chain fluctuating in a\ntwo-dimensional nematic background and a freely floating material line buffeted\nby a two-dimensional turbulent fluid in the inertial (Kraichnan) regime. Under\ncertain conditions, the back-reaction of the line on the turbulent flow may be\nneglected. The fractal exponent related to the size-contour relation of the\nmaterial line is connected to a \"nematic\" correlation function in the bulk."
    },
    {
        "anchor": "Electrical charging during the sharkskin instability of a metallocene\n  melt: Flow instabilities are widely studied because of their economical and\ntheoretical interest, however few results have been published about the polymer\nelectrification during the extrusion. Nevertheless the generation of the\nelectrical charges is characteristic of the interaction between the polymer\nmelt and the die walls. In our study, the capillary extrusion of a metallocene\npolyethylene (mPE) through a tungsten carbide die is characterized through\naccurate electrical measurements thanks a Faraday pail. No significant charges\nare observed since the extrudate surface remains smooth. However, as soon as\nthe sharkskin distortion appears, measurable charges are collected (around 5\n10-8 C/m2). Higher level of charges are measured during the spurt or the\ngross-melt fracture (g.m.f) defects. This work is focused on the electrical\ncharging during the sharkskin instability. The variation of the electrical\ncharges versus the apparent wall shear stress is investigated for different die\ngeometries. This curve exhibits a linear increase, followed by a sudden growth\njust before the onset of the spurt instability. This abrupt charging\ncorresponds also to the end of the sharkskin instability. It is also well-known\nthat wall slip appears just at the same time, with smaller velocity values than\nduring spurt flow. Our results indicate that electrification could be a\nsignature of the wall slip. We show also that the electrification curves can be\nshifted according to the time-temperature superposition principle, leading to\nthe conclusion that molecular features of the polymer are also involved in this\nprocess.",
        "positive": "Navier-Stokes hydrodynamics of thermal collapse in a freely cooling\n  granular gas: We employ Navier-Stokes granular hydrodynamics to investigate the long-time\nbehavior of clustering instability in a freely cooling dilute granular gas in\ntwo dimensions. We find that, in circular containers, the homogeneous cooling\nstate (HCS) of the gas loses its stability via a sub-critical pitchfork\nbifurcation. There are no time-independent solutions for the gas density in the\nsupercritical region, and we present analytical and numerical evidence that the\ngas develops thermal collapse unarrested by heat diffusion. To get more\ninsight, we switch to a simpler geometry of a narrow-sector-shaped container.\nHere the HCS loses its stability via a transcritical bifurcation. For some\ninitial conditions a time-independent inhomogeneous density profile sets in,\nqualitatively similar to that previously found in a narrow-channel geometry.\nFor other initial conditions, however, the dilute gas develops thermal collapse\nunarrested by heat diffusion. We determine the dynamic scalings of the flow\nclose to collapse analytically and verify them in hydrodynamic simulations. The\nresults of this work imply that, in dimension higher than one, Navier-Stokes\nhydrodynamics of a dilute granular gas is prone to finite-time density blowups.\nThis provides a natural explanation to the formation of densely packed clusters\nof particles in a variety of initially dilute granular flows."
    },
    {
        "anchor": "Effect of Thermal and Mechanical Rejuvenation on Rheological Behavior of\n  Chocolate: Chocolate is known to undergo solid-liquid transition upon an increase in\ntemperature as well as under application of deformation field. Upon sudden\nreduction in temperature from a molten state (or thermal rejuvenation),\nrheological properties of chocolate undergo evolution as a function of time\nunder isothermal conditions, a behavior reminiscent of physical aging in\npolymeric glasses. Then again, subsequent to cessation of shear flow (or\nmechanical rejuvenation), chocolate shows temporal evolution of the rheological\nproperties, a behavior similar to physical aging in soft glassy materials. In\nthis work, we evaluate three rheological properties, namely, dynamic moduli,\nrelaxation time spectrum and characteristic relaxation time of chocolate, and\ncompare their evolution after thermal as well as mechanical rejuvenation. We\nobserve that the evolution of the rheological properties subsequent to\nmechanical rejuvenation is distinctly different from that of thermal\nrejuvenation, wherein the evolution is more gradual in the former case. On the\none hand, this work provides unique insights into how shear affects the\nrheological behavior of chocolate. On the other hand, this work clearly\nsuggests that chocolate explores different sections of the energy landscape\nafter mechanical rejuvenation compared to that of thermal rejuvenation.",
        "positive": "Dynamics of semi-flexible polymer solutions in the highly entangled\n  regime: We present experimental evidence that the effective medium approximation\n(EMA), developed by D.C. Morse [Phys. Rev. E {\\bf 63}, 031502, (2001)],\nprovides the correct scaling law of the macroscopic plateau modulus\n$G^{0}\\propto\\rho^{4/3}L^{-1/3}_{p}$ (where $\\rho$ is the contour length per\nunit volume and $L_{p}$ is the persistence length) of semi-flexible polymer\nsolutions, in the highly entangled concentration regime. Competing theories,\nincluding a self-consistent binary collision approximation (BCA), have instead\npredicted $G^{0}\\propto\\rho^{7/5}L^{-1/5}_{p}$. We have tested both the EMA and\nBCA scaling predictions using actin filament (F-actin) solutions which permit\nexperimental control of $L_p$ independently of other parameters. A combination\nof passive video particle tracking microrheology and dynamic light scattering\nyields independent measurements of the elastic modulus $G$ and $L_{p}$\nrespectively. Thus we can distinguish between the two proposed laws, in\ncontrast to previous experimental studies, which focus on the (less\ndiscriminating) concentration functionality of $G$."
    },
    {
        "anchor": "Solution of the problem of catastrophic relaxation of homogeneous spin\n  precession in superfluid $^3$He-B: The quantitative analysis of the \"catastrophic relaxation\" of the coherent\nspin precession in $^3$He-B is presented. This phenomenon has been observed\nbelow the temperature about 0.5 T$_c$ as an abrupt shortening of the induction\nsignal decay. It is explained in terms of the decay instability of homogeneous\ntransverse NMR mode into spin waves of the longitudinal NMR. Recently the cross\ninteraction amplitude between the two modes has been calculated by Sourovtsev\nand Fomin \\cite{SF} for the so-called Brinkman-Smith configuration, i.e. for\nthe orientation of the orbital momentum of Cooper pairs along the magnetic\nfield, ${\\bf L}\\parallel {\\bf H}$. In their treatment, the interaction is\ncaused by the anisotropy of the speed of the spin waves. We found that in the\nmore general case of the non-parallel orientation of ${\\bf L}$ corresponding to\nthe typical conditions of experiment, the spin-orbital interaction provides the\nadditional interaction between the modes. By analyzing experimental data we are\nable to distinguish which contribution is dominating in different regimes.",
        "positive": "Strain Analysis of a Chiral Smectic A Elastomer: We present a detailed analysis of the molecular packing of a strained liquid\ncrystal elastomer composed of chiral mesogens in the smectic A phase. X-ray\ndiffraction patterns of the elastomer collected over a range of orientations\nwith respect to the X-ray beam were used to reconstruct the three-dimensional\nscattering intensity as a function of tensile strain. For the first time, we\nshow that the smectic domain order is preserved in these strained elastomers.\nChanges in the intensity within a given scattering plane are due to\nreorientation, and not loss, of the molecular order in directions orthogonal to\nthe applied strain. Incorporating the physical parameters of the elastomer, a\nnonlinear elastic model is presented to describe the rotation of the\nsmectic-layered domains under strain, thus providing a fundamental analysis to\nthe mechanical response of these unique materials."
    },
    {
        "anchor": "On the shape of barchan dunes: Barchans are crescent-shaped sand dunes forming in aride regions with\nunidirectional wind and limited sand supply. We report analytical and numerical\nresults for dune shapes under different environmental conditions as obtained\nfrom the so-called `minimal model' of aeolian sand dunes. The profiles of\nlongitudinal vertical slices (i.e. along the wind direction) are analyzed as a\nfunction of wind speed and sand supply. Shape transitions can be induced by\nchanges of mass, wind speed and sand supply. Within a minimal extension of the\nmodel to the transverse direction the scale-invariant profile of transverse\nvertical cuts can be derived analytically.",
        "positive": "Dumbbells in suspension: A numerical study on their dynamics and shear\n  viscosity: The dynamics of elastic dumbbells in linear shear flow is investigated by\nfluid particle dynamics simulations at small Reynolds numbers. The positive\ncontribution of a single dumbbell to the effective shear viscosity is\ndetermined via the extra stress exerted at the boundaries of the shear cell and\nthe difference to the contributions obtained via the Kramers-Kirkwood formula\nare described. For a small Weissenberg number and when the mean dumbbell length\nbecomes larger than the mean next-neighbor distance, the contribution of\ninteracting dumbbells to the mean shear viscosity exceeds significantly the\ncontribution of unconnected beads occupying the same volume fraction."
    },
    {
        "anchor": "Colloids and polymers in random colloidal matrices: demixing under\n  good-solvent conditions: We consider a simplified coarse-grained model for colloid-polymer mixtures,\nin which polymers are represented as monoatomic molecules interacting by means\nof pair potentials. We use it to study polymer-colloid segregation in the\npresence of a quenched matrix of colloidal hard spheres. We fix the\npolymer-to-colloid size ratio to 0.8 and consider matrices such that the\nfraction f of the volume that is not accessible to the colloids due to the\nmatrix is equal to 40%. As in the Asakura-Oosawa-Vrij (AOV) case, we find that\nbinodal curves in the polymer and colloid volume-fraction plane have a small\ndependence on disorder. As for the position of the critical point, the behavior\nis different from that observed in the AOV case: while the critical colloid\nvolume fraction is essentially the same in the bulk and in the presence of the\nmatrix, the polymer volume fraction at criticality increases as f increases. At\nvariance with the AOV case, no capillary colloid condensation or evaporation is\ngenerically observed.",
        "positive": "Fluctuations of Fluctuation-Induced \"Casimir\" Forces: The force experienced by objects embedded in a correlated medium undergoing\nthermal fluctuations--the so-called fluctuation--induced force--is actually\nitself a fluctuating quantity. We compute the corresponding probability\ndistribution and show that it is a Gaussian centered on the well-known Casimir\nforce, with a non-universal standard deviation that can be typically as large\nas the mean force itself. The relevance of these results to the experimental\nmeasurement of fluctuation-induced forces is discussed, as well as the\ninfluence of the finite temporal resolution of the measuring apparatus."
    },
    {
        "anchor": "Fluid-fluid transitions of hard spheres with a very short-range\n  attraction: Hard spheres with an attraction of range a tenth to a hundredth of the sphere\ndiameter are constrained to remain fluid even at densities when monodisperse\nparticles at equilibrium would have crystallised, in order to compare with\nexperimental systems which remain fluid. They are found to have a fluid-fluid\ntransition at high density. As the range of the attraction tends to zero, the\ndensity at the critical point tends towards the random-close-packing density of\nhard spheres.",
        "positive": "The role of dilation and confining stresses in shear thickening of dense\n  suspensions: Many densely packed suspensions and colloids exhibit a behavior known as\nDiscontinuous Shear Thickening in which the shear stress jumps dramatically and\nreversibly as the shear rate is increased. We performed rheometry and video\nmicroscopy measurements on a variety of suspensions to determine the mechanism\nfor this behavior. Shear profiles and normal stress measurements indicate that,\nin the shear thickening regime, stresses are transmitted through frictional\nrather than viscous interactions, and come to the surprising conclusion that\nthe local constitutive relation between stress and shear rate is not\nnecessarily shear thickening. If the suspended particles are heavy enough to\nsettle we find the onset stress of shear thickening tau_min corresponds to a\nhydrostatic pressure from the weight of the particle packing where neighboring\nparticles begin to shear relative to each other. Above tau_min, dilation is\nseen to cause particles to penetrate the liquid-air interface of the sheared\nsample. The upper stress boundary tau_max of the shear thickening regime is\nshown to roughly match the ratio of surface tension divided by a radius of\ncurvature on the order of the particle size. These results suggest a new model\nin which the increased dissipation in the shear thickening regime comes from\nfrictional stresses that emerge as dilation is frustrated by a confining stress\nfrom surface tension at the liquid-air interface. When instead the suspensions\nare confined by solid walls and have no liquid-air interface, we find tau_max\nis set by the stiffness of the most compliant boundary which frustrates\ndilation. This rheology can be described by a non-local constitutive relation\nin which the local relation between stress and shear rate is shear thinning,\nbut where the stress increase comes from a normal stress term which depends on\nthe global dilation."
    },
    {
        "anchor": "Volume fluctuations and geometrical constraints in granular packs: Structural organization and correlations are studied in very large packings\nof equally sized acrylic spheres, reconstructed in three-dimensions by means of\nX-ray computed tomography. A novel technique, devised to analyze correlations\namong more than two spheres, shows that the structural organization can be\nconveniently studied in terms of a space-filling packing of irregular\ntetrahedra. The study of the volume distribution of such tetrahedra reveals an\nexponential decay in the region of large volumes; a behavior that is in very\ngood quantitative agreement with theoretical prediction. I argue that the\nsystem's structure can be described as constituted of two phases: 1) an\n`unconstrained' phase which freely shares the volume; 2) a `constrained' phase\nwhich assumes configurations accordingly with the geometrical constraints\nimposed by the condition of non-overlapping between spheres and mechanical\nstability. The granular system exploits heterogeneity maximizing freedom and\nentropy while constraining mechanical stability.",
        "positive": "Thermodynamic limits of sperm swimming precision: Sperm swimming is crucial to fertilise the egg, in nature and in assisted\nreproductive technologies. Modelling the sperm dynamics involves elasticity,\nhydrodynamics, internal active forces, and out-of-equilibrium noise. Here we\ndemonstrate experimentally the relevance of energy dissipation for sperm\nbeating fluctuations. For each motile cell, we reconstruct the time-evolution\nof the two main tail's spatial modes, which together trace a noisy limit cycle\ncharacterised by a maximum level of precision $p_{max}$. Our results indicate\n$p_{max} \\sim 10^2 s^{-1}$, remarkably close to the estimated precision of a\ndynein molecular motor actuating the flagellum, which is bounded by its energy\ndissipation rate according to the Thermodynamic Uncertainty Relation. Further\nexperiments under oxygen deprivation show that $p_{max}$ decays with energy\nconsumption, as it occurs for a single molecular motor. Both observations can\nbe explained by conjecturing a high level of coordination among the\nconformational changes of dynein motors. This conjecture is supported by a\ntheoretical model for the beating of an ideal flagellum actuated by a\ncollection of motors, including a motor-motor nearest neighbour coupling of\nstrength $K$: when $K$ is small the precision of a large flagellum is much\nhigher than the single motor one. On the contrary, when $K$ is large the two\nbecome comparable."
    },
    {
        "anchor": "Controlling placement of nonspherical (boomerang) colloids in nematic\n  cells with photopatterned director: Placing colloidal particles in predesigned sites represents a major challenge\nof the current state-of-the-art colloidal science. Nematic liquid crystals with\nspatially varying director patterns represent a promising approach to achieve a\nwell-controlled placement of colloidal particles thanks to the elastic forces\nbetween the particles and the surrounding landscape of molecular orientation.\nHere we demonstrate how the spatially varying director field can be used to\ncontrol placement of non-spherical particles of boomerang shape. The boomerang\ncolloids create director distortions of a dipolar symmetry. When a boomerang\nparticle is placed in a periodic splay-bend director pattern, it migrates\ntowards the region of a maximum bend. The behavior is contrasted to that one of\nspherical particles with normal surface anchoring, which also produce dipolar\ndirector distortions, but prefer to compartmentalize into the regions with a\nmaximum splay. The splay-bend periodic landscape thus allows one to spatially\nseparate these two types of particles. By exploring overdamped dynamics of the\ncolloids, we determine elastic driving forces responsible for the preferential\nplacement. Control of colloidal locations through patterned molecular\norientation can be explored for future applications in microfluidic, lab on a\nchip, sensing and sorting devices.",
        "positive": "Methodology to Construct Large Realizations of Perfectly Hyperuniform\n  Disordered Packings: Disordered hyperuniform packings are unusual amorphous states of two-phase\nmaterials that are endowed with exotic physical properties. Such hyperuniform\nsystems are characterized by an anomalous suppression of volume-fraction\nfluctuations at infinitely long-wavelengths, compared to ordinary disordered\nmaterials. While there has been growing interest in such singular states of\namorphous matter, a major obstacle has been an inability to produce large\nhyperuniform samples due to practical limitations of conventional methods. To\novercome these limitations, we introduce a general theoretical methodology to\nconstruct perfectly hyperuniform packings in $d$-dimensional Euclidean space.\nSpecifically, beginning with an initial general tessellation of space that\nmeets a \"bounded-cell\" condition, hard particles are placed inside each cell\nsuch that the packing fraction within the cell becomes identical to the global\npacking fraction. We prove that the constructed packings are perfectly\nhyperuniform in the infinite-sample-size limit and their hyperuniformity is\nindependent of particle shapes, positions, and numbers per cell. We employ two\ndistinct types of initial tessellations: Voronoi as well as sphere\ntessellations. Beginning with Voronoi tessellations, we show that our algorithm\ncan remarkably convert extremely large nonhyperuniform packings into\nhyperuniform ones in $\\mathbb{R}^2$ and $\\mathbb{R}^3$. Implementing our\ntheoretical methodology on sphere tessellations, we establish the\nhyperuniformity of the classical Hashin-Shtrikman multiscale coated-spheres\nstructures that possess optimal effective transport and elastic properties. In\naddition, the tunability of our methodology offers promise for discovery of\nnovel disordered hyperuniform two-phase materials."
    },
    {
        "anchor": "Surface effects on anti-plane shear waves propagating in\n  magneto-electro-elastic nano-plates: Material surface may have a remarkable effect on the mechanical behavior of\nmagneto-electro-elastic (or multiferroic) structures at nano-scale. In this\npaper, a surface magneto-electro-elasticity theory (or effective boundary\ncondition formulation), which governs the motion of the material surface of\nmagneto-electro-elastic nano-plates, is established by employing the\nstate-space formalism. The properties of anti-plane shear (SH) waves\npropagating in a transversely isotropic magneto-electro-elastic plate with\nnano-thickness are investigated by taking surface effects into account. The\nsize-dependent dispersion relations of both antisymmetric and symmetric SH\nwaves are presented. The thickness-shear frequencies and the asymptotic\ncharacteristics of the dispersion relations considering surface effects are\ndetermined analytically as well. Numerical results show that surface effects\nplay a very pronounced role in elastic wave propagation in\nmagneto-electro-elastic nano-plates, and the dispersion properties depend\nstrongly on the chosen surface material parameters of magneto-electro-elastic\nnano-plates. As a consequence, it is possible to modulate the waves in\nmagneto-electro-elastic nano-plates through surface engineering.",
        "positive": "Active fractal networks with stochastic force monopoles and force\n  dipoles unravel subdiffusion of chromosomal loci: We study the Rouse-type dynamics of elastic fractal networks with embedded,\nstochastically driven, active force monopoles and dipoles, that are temporally\ncorrelated. We compute, analytically -- using a general theoretical framework\n-- and via Langevin dynamics simulations, the mean square displacement of a\nnetwork bead. Following a short-time super-diffusive behavior, force monopoles\nyield anomalous subdiffusion with an exponent identical to that of the thermal\nsystem. Force dipoles do not induce subdiffusion, and result in rotational\nmotion of the whole network -- as found for micro-swimmers -- and network\ncollapses beyond a critical force amplitude. The collapse persists with\nincreasing system size, signifying a true first-order dynamical phase\ntransition. We conclude that the observed identical subdiffusion exponents of\nchromosomal loci in normal and ATP-depleted cells are attributed to active\nforce monopoles rather than force dipoles."
    },
    {
        "anchor": "Melting line and thermodynamic properties of a supeionic compound\n  SrCl$_2$ by molecular dynamics simulation: In the present paper we study the thermodynamic properties of superionic\nconductor $SrCl_2$ at high temperatures by means of molecular dynamics method.\nFirstly, we calculate the melting line. Then we compute the equations of state\nand the response functions (heat capacity, thermal expansion coefficient, etc)\nat the temperatures up to the melting. We show that the response functions show\nmaxima or minima at the temperatures well above the temperature of transition\ninto the conductive state, and therefore are not related to this transition.",
        "positive": "On the influence of molecular structure on the conductivity of\n  electrolyte solutions - sodium nitrate in water: Theoretical calculations of the conductivity of sodium nitrate in water are\npresented and compared with experimental measurements. The method of direct\ncorrelation force in the framework of the interionic theory is used for the\ncalculation of transport properties in connection with the associative mean\nspherical approximation (AMSA). The effective interactions between ions in\nsolutions are derived with the help of Monte Carlo and Molecular Dynamics\ncalculations on the Born-Oppenheimer level. This work is based on earlier\ntheoretical and experimental studies of the structure of concentrated aqueous\nsodium nitrate solutions."
    },
    {
        "anchor": "Experimental assessment of the effective friction at the base of\n  granular chute flows on smooth incline: We report on direct measurements of the basal force components for granular\nmaterial flowing down a smooth incline. We investigate granular flows for a\nlarge range of inclination angles from teta=13.4{\\deg} to 83.6{\\deg} and\nvarious gate opening of the chute. We find that the effective basal friction\ncoefficient, muB, obtained from the ratio of the longitudinal force to the\nnormal one exhibits a systematic increase with increasing slope angle and a\nsignificant weakening with increasing particle hold-up H (the depth-integrated\nparticle volume fraction). At low angles, the basal friction is slightly less\nthan or equal to tan(teta). The deviation from tan(teta) can be interpreted as\na contribution from the side-wall to the overall friction. At larger angles,\nthe basal friction muB saturates at an asymptotic value that is dependent on\nthe gate opening of the chute. Importantly, our data confirm the outcomes of\nrecent discrete numerical simulations. First, for steady and fully developed\nflows as well as for moderately accelerated ones, the variation of the basal\nfriction can be captured through a unique dimensionless number, the Froude\nnumber Fr, defined as Fr=U/(gHcos(teta))^1/2, where U is the mean flow\nvelocity. Second, the mean velocity scales with the particle hold-up H with a\npower exponent close to 1/4, contrasting with the Bagnold scaling (U~H^3/2).",
        "positive": "A Coupled Map Lattice Model for Rheological Chaos in Sheared Nematic\n  Liquid Crystals: A variety of complex fluids under shear exhibit complex spatio-temporal\nbehaviour, including what is now termed rheological chaos, at moderate values\nof the shear rate. Such chaos associated with rheological response occurs in\nregimes where the Reynolds number is very small. It must thus arise as a\nconsequence of the coupling of the flow to internal structural variables\ndescribing the local state of the fluid. We propose a coupled map lattice (CML)\nmodel for such complex spatio-temporal behaviour in a passively sheared nematic\nliquid crystal, using local maps constructed so as to accurately describe the\nspatially homogeneous case. Such local maps are coupled diffusively to nearest\nand next nearest neighbours to mimic the effects of spatial gradients in the\nunderlying equations of motion. We investigate the dynamical steady states\nobtained as parameters in the map and the strength of the spatial coupling are\nvaried, studying local temporal properties at a single site as well as\nspatio-temporal features of the extended system. Our methods reproduce the full\nrange of spatio-temporal behaviour seen in earlier one-dimensional studies\nbased on partial differential equations. We report results for both the one and\ntwo-dimensional cases, showing that spatial coupling favours uniform or\nperiodically time-varying states, as intuitively expected. We demonstrate and\ncharacterize regimes of spatio-temporal intermittency out of which chaos\ndevelops. Our work suggests that such simplified lattice representations of the\nspatio-temporal dynamics of complex fluids under shear may provide useful\ninsights as well as fast and numerically tractable alternatives to continuum\nrepresentations."
    },
    {
        "anchor": "Chain Collapse and Counterion Condensation in Dilute Polyelectrolyte\n  Solutions: A new quantitative theory for polyelectrolytes in salt free dilute solutions\nis developed. Depending on the electrostatic interaction strength,\npolyelectrolytes in solutions can undergo strong stretching (with\npolyelectrolyte dimension R_g\\sim l_B^{1/3}N, where l_B is the Bjerrum length\nand N is the number of the chain segments) or strong compression (with R_g\\sim\nl_B^{-1/2}N^{1/3}). A strong polymer collapse occurs as a first-order phase\ntransition due to accompanying counterion condensation.",
        "positive": "Focusing of Active Particles in a Converging Flow: We consider active particles swimming in a convergent fluid flow in a\ntrapezoid nozzle with no-slip walls. We use mathematical modeling to analyze\ntrajectories of these particles inside the nozzle. By extensive Monte Carlo\nsimulations, we show that trajectories are strongly affected by the background\nfluid flow and geometry of the nozzle leading to wall accumulation and upstream\nmotion (rheotaxis). In particular, we describe the non-trivial focusing of\nactive rods depending on physical and geometrical parameters. It is also\nestablished that the convergent component of the background flow leads to\nstability of both downstream and upstream swimming at the centerline. The\nstability of downstream swimming enhances focusing, and the stability of\nupstream swimming enables rheotaxis in the bulk."
    },
    {
        "anchor": "Surface modes and critical velocity in trapped Bose-condensates: We propose the novel mechanism leading to superfluidity breakdown in dilute\nBose-condensed gases. We discuss the properties and highlight the role played\nby surface excitations in trapped condensates. We show that the critical\nvelocity measured in recent experiments is nothing else but the critical\nvelocity associated with the spontaneous creation of surface modes. The latter\nturns out to be larger than that found by the analysis of a superflow stability\nwith respect to vortex nucleation.",
        "positive": "Fluid rings and droplet arrays via rim streaming: Tip-streaming generates micron- and submicron- sized droplets when a thin\nthread pulled from the pointy end of a drop disintegrates. Here, we report\nstreaming from the equator of a drop placed in a uniform electric field. The\ninstability generates concentric fluid rings encircling the drop, which break\nup to form an array of microdroplets in the equatorial plane. We show that the\nstreaming results from an interfacial instability at the stagnation line of the\nelectrohydrodynamic flow, which creates a sharp rim. The flow draws from the\nrim a thin sheet which destabilizes and sheds fluid cylinders. This streaming\nphenomenon provides a new route for generating monodisperse microemulsions."
    },
    {
        "anchor": "Studying Soft Matter with \"Soft\" Potentials: Fast Lattice Monte Carlo\n  Simulations and Corresponding Lattice Self-Consistent Field Calculations: The basic idea of fast Monte Carlo (MC) simulations is to perform\nparticle-based MC simulations with the excluded-volume interactions modeled by\n\"soft\" repulsive potentials that allow particle overlapping. This gives much\nfaster system relaxation and better sampling of the configurational space than\nconventional molecular simulations with \"hard\" repulsions that prevent particle\noverlapping. Here we present fast lattice MC (FLMC) simulations for confined\nhomopolymers, where multiple occupancy of lattice sites is allowed with a\nproper Boltzmann weight and thus the evaluation of nearest-neighbor\ninteractions can also be avoided. When compared with the corresponding lattice\nfield theories based on the \\emph{same} Hamiltonian, FLMC simulations further\nprovide a powerful means for unambiguously and quantitatively revealing the\ncorrelation/fluctuation effects.",
        "positive": "Dumbbell impurities in 2D crystals of repulsive colloidal spheres induce\n  particle-bound dislocations: Impurity-induced defects play a crucial role for the properties of crystals,\nbut little is known about impurities with anisotropic shape. Here, we study how\ncolloidal dumbbells distort and interact with a hexagonal crystal of charged\ncolloidal spheres at a fluid interface. We find that subtle changes in the\ndumbbell length induce a transition from a local distortion to a particle-bound\ndislocation, and determine how the dumbbell moves inside the repulsive\nhexagonal lattice. Our results provide new routes towards controlling material\nproperties through particle-bound dislocations."
    },
    {
        "anchor": "Spiralling molecular structures and chiral selectivity in model\n  membranes: Since the lipid raft model was developed at the end of the last century, it\nbecame clear that the specific molecular arrangements of phospholipid\nassemblies within a membrane have profound implications in a vast range of\nphysiological functions. Studies of such condensed lipid islands in model\nsystems using fluorescence and Brewster angle microscopies have shown a wide\nrange of sizes and morphologies, with suggestions of substantial in-plane\nmolecular anisotropy and mesoscopic structural chirality. Whilst these\nvariations can significantly alter many membrane properties including its\nfluidity, permeability, and molecular recognition, the details of the in-plane\nmolecular orientations underlying these traits remain largely unknown. Here, we\nuse phase-resolved sum-frequency generation microscopy on model membranes of\nphospholipid monolayers with mixed molecular chirality, which form micron-scale\ncircular domains of condensed lipids, to fully determine their\nthree-dimensional molecular structure. We find that the domains possess curved\nmolecular directionality with spiralling mesoscopic packing. By comparing\ndifferent enantiomeric mixtures, both the molecular and spiral turning\ndirections are shown to depend on the lipid chirality, but with a clear\ndeviation from mirror symmetry in the formed structures. This demonstrates\nstrong enantioselectivity in the domain growth process, which has potential\nconnections to the evolution of homochirality in all living organisms as well\nas implications for enantioselective drug design.",
        "positive": "Mechanics and wrinkling patterns of pressurized bent tubes: Take a drinking straw and bend it from its ends. After sufficient bending,\nthe tube buckles forming a kink, where the curvature is localized in a very\nsmall area. This instability, known generally as the Brazier effect, is\ninherent to thin-walled cylindrical shells, which are particularly ubiquitous\nin living systems, such as rod-shaped bacteria. However, tubular biological\nstructures are often pressurized, and the knowledge of the mechanical response\nupon bending in this scenario is limited. In this work, we use a computational\nmodel to study the mechanical response and the deformations as a result of\nbending pressurized tubes. In addition, we employ tension-field theory to\ndescribe the mechanical behaviour before and after the wrinkling transition.\nFurthermore, we investigate the development and evolution of wrinkle patterns\nbeyond the instability, showing different wrinkled configurations. We discover\nthe existence of a multi-wavelength mode following the purely sinusoidal\nwrinkles and anticipating the kinked configuration of the tube."
    },
    {
        "anchor": "Density controls the kinetic stability of ultrastable glasses: We use a swap Monte Carlo algorithm to numerically prepare bulk glasses with\nkinetic stability comparable to that of glass films produced experimentally by\nphysical vapor deposition. By melting these systems into the liquid state, we\nshow that some of our glasses retain their amorphous structures longer than\n10^5 times the equilibrium structural relaxation time. This exceptional kinetic\nstability cannot be achieved experimentally for bulk materials. We perform\nsimulations at both constant volume and constant pressure to demonstrate that\nthe density mismatch between the ultrastable glass and the equilibrium liquid\naccounts for a major part of the observed kinetic stability.",
        "positive": "Aqueous foams in microgravity, measuring bubble sizes: The paper describes a study of wet foams in microgravity whose bubble size\ndistribution evolves due to diffusive gas exchange. We focus on the comparison\nbetween the size of bubbles determined from images of the foam surface and the\nsize of bubbles in the bulk foam, determined from Diffuse Transmission\nSpectroscopy (DTS). Extracting the bubble size distribution from images of a\nfoam surface is difficult so we have used three different procedures : manual\nanalysis, automatic analysis with a customized Python script and machine\nlearning analysis. Once various pitfalls were identified and taken into\naccount, all the three procedures yield identical results within error bars.\nDTS only allows the determination of an average bubble radius which is\nproportional to the photon transport mean free path $\\ell^*$. The relation\nbetween the measured diffuse transmitted light intensity and {$\\ell^*$}\npreviously derived for slab-shaped samples of infinite lateral extent does not\napply to the cuboid geometry of the cells used in the microgravity experiment.\nA new more general expression of the diffuse intensity transmitted with\nspecific optical boundary conditions has been derived and applied to determine\nthe average bubble radius. The temporal evolution of the average bubble radii\ndeduced from DTS and of the same average radii of the bubbles measured at the\nsample surface are in very good agreement throughout the coarsening. Finally,\nground experiments were performed to compare bubble size distributions in a\nbulk wet foam and at its surface at times so short that diffusive gas exchange\nis insignificant. They were found to be similar, confirming that bubbles seen\nat the surface are representative of the bulk foam bubbles."
    },
    {
        "anchor": "Theory of Chiral Imprinting: We present a continuum model for a nematic elastomer network formed in a\nchiral environment, for instance in the presence of a chiral solvent. When this\nenvironment is removed, the network can retain some memory of its chiral\ngenesis. We predict the residual chiral order parameter for a number of\npossible scenarios, and go on to examine the robustness (stability) of the\nimprinted chirality. We show that a twist-untwist transition can take place,\nwhich determines whether the imprinting has been successful. A transition is\nvia a coarsening of the helical director pattern and a lengthening of its\npitch. Finally, the effect due to a subsequent swelling by an achiral solvent,\nor by a solvent of differing chirality, is considered.",
        "positive": "Controlling anomalous stresses in soft field-responsive systems: We report a new phenomenon occurring in field-responsive suspensions:\nshear-induced anomalous stresses. Competition between a rotating field and a\nshear flow originates a multiplicity of anomalous stress behaviors in\nsuspensions of bounded dimers constituted by induced dipoles. The great variety\nof stress regimes includes non-monotonous behaviors, multi-resonances, negative\nviscosity effect and blockades. The reversibility of the transitions between\nthe different regimes and the self-similarity of the stresses make this\nphenomenon controllable and therefore applicable to modify macroscopic\nproperties of soft condensed matter phases"
    },
    {
        "anchor": "Chiral flow in a binary mixture of two-dimensional active disks: We study, experimentally, the dynamics of a binary mixture of air-fluidized\ndisks. The disks are chiral since they incorporate a set of blades with\nconstant tilt. Both species are identical except for their blades tilt angle,\nwhich is rotated by 180o in the second species. We analyze the phase behavior\nof the system. Our analysis reveals a wide range of different fluid dynamics,\nincluding chiral flow. This chiral flow features in its base state a large\nvortex. We report, for certain ranges of relative particle density of each\nspecies, inversion of the vorticity of this vortex. We discuss on the possible\nmechanisms behind these chiral flow transitions.",
        "positive": "Nonlinear response functions in an exponential trap model: The nonlinear response to an oscillating field is calculated for a kinetic\ntrap model with an exponential density of states and the results are compared\nto those for the model with a Gaussian density of states. The calculations are\nlimited to the high temperature phase of the model. It is found that the\nresults are qualitatively different only in a temperature range near the glass\ntransition temperature $T_0$ of the exponential model. While for the Gaussian\nmodel the choice of the dynamical variable that couples to the field has no\nimpact on the shape of the linear response, this is different for the\nexponential model. Here, it is found that also the relaxation time strongly\ndepends on the variable chosen. Furthermore, the modulus of the frequency\ndependent third-order response shows either a peak or exhibits a monotonuous\ndecay from a finite low-frequency limit to a vanishing response at high\nfrequencies depending on the dynamical variable. For variables that give rise\nto a peak in the modulus it is found that its height either increases or\ndecreases as a function of temperature, again depending on the details of the\nchoice of the variable. The peak value of the modulus shows a scaling behavior\nnear $T_0$. It is found that for some variables the low-frequency limit of the\ncubic response diverges at the glass transition temperature and also at a\nfurther temperature determined by the particular variable. A recently proposed\napproximation that relates the cubic response to a four-time correlation\nfunction does not give reliable results due to a wrong estimate of the\nlow-frequency limit of the response."
    },
    {
        "anchor": "Bending-Rotation coupling in the viscoelasticity of semi-flexible\n  polymers -- Rigorous perturbation analysis from the rod limit: Brownian motion and viscoelasticity of semi-flexible polymers is a subject\nthat has been studied for many years. Still, rigorous analysis has been\nhindered due to the difficulty in handling the constraint that polymer chains\ncannot be stretched along the contour. Here, we show a straightforward method\nto solve the problem. We consider a stiff polymer that has a persistent length\n$L_p$ much larger than the contour length $L$. We express the polymer\nconfiguration using three types of variables: the position vector of the center\nof mass $R_c$, the unit vector $n$ along the main axis, and the normal\ncoordinates $u_p$ for bending. Solving the Smoluchowski equation for the\ndistribution function of these variables, we calculate the equilibrium time\ncorrelation function $ \\langle P(t)\\cdot P(0) \\rangle$ of the end-to-end vector\n$P$ and the complex modulus $G^*(\\omega)$ of dilute solution. They include the\nbending effect to the first order in $\\theta \\equiv L/L_p$ and reduce to the\nexact results for the rigid rod in the limit of $\\theta \\to 0$. The rotational\ndiffusion coefficient increases slightly by the semi-flexibility because the\nequilibrium length of the semi-flexible polymer is smaller than that of the\nrigid rod with the same contour length. The storage modulus shows the same\nasymptotic dependence $G'(\\omega) \\sim \\omega^{3/4}$ predicted by Shankar,\nPasquali, and Morse [J. Rheol. 2002, 46, 1111--1154]. The high-frequency\nviscosity is predicted to be dependent on the thickness of the semi-flexible\npolymers.",
        "positive": "Temperature Dependence of Anchoring Energy of MBBA on SiO-Evaporated\n  Substrate: The temperature behaviour of the anchoring energy of nematic liquid crystal\nMBBA at the substrates with oblique SiO evaporation and director orientation at\nthe interface have been studied by means of magnetic Freedericksz transition\ntechnique. The temperature dependence of the coefficients in the\nphenomenological model of surface anchoring energy has been determined."
    },
    {
        "anchor": "Scattering and absorption of light by periodic and nearly periodic\n  metallodielectric structures: We consider the effect of different approximations to the dielectric function\nof a silver sphere on the absorption of light by two-dimensional and\nthree-dimensional periodic and non-periodic arrays of non-overlapping silver\nspheres in a host dielectric medium. We present also some results on the band\nstructure and the absorption coefficient of light by photonic crystals\nconsisting of non-overlapping silver-coated spheres in a dielectric medium.",
        "positive": "Electrostatics of ions inside the nanopores and trans-membrane channels: A model of a finite cylindrical ion channel through a phospholipid membrane\nof width $L$ separating two electrolyte reservoirs is studied. Analytical\nsolution of the Poisson equation is obtained for an arbitrary distribution of\nions inside the trans-membrane pore. The solution is asymptotically exact in\nthe limit of large ionic strength of electrolyte on the two sides of membrane.\nHowever, even for physiological concentrations of electrolyte, the\nelectrostatic barrier sizes found using the theory are in excellent agreement\nwith the numerical solution of the Poisson equation. The analytical solution is\nused to calculate the electrostatic potential energy profiles for pores\ncontaining charged protein residues. Availability of a semi-exact interionic\npotential should greatly facilitate the study of ionic transport through\nnanopores and ion channels."
    },
    {
        "anchor": "Yukawa potentials in systems with partial periodic boundary conditions\n  II : Lekner sums for quasi-two dimensional systems: Yukawa potentials may be long ranged when the Debye screening length is\nlarge. In computer simulations, such long ranged potentials have to be taken\ninto account with convenient algorithms to avoid systematic bias in the\nsampling of the phase space. Recently, we have provided Ewald sums for\nquasi-two dimensional systems with Yukawa interaction potentials [M. Mazars,\n{\\it J. Chem. Phys.}, {\\bf 126}, 056101 (2007) and M. Mazars, {\\it Mol. Phys.},\nPaper I]. Sometimes, Lekner sums are used as an alternative to Ewald sums for\nCoulomb systems. In the present work, we derive the Lekner sums for quasi-two\ndimensional systems with Yukawa interaction potentials and we give some\nnumerical tests for pratical implementations. The main result of this paper is\nto outline that Lekner sums cannot be considered as an alternative to Ewald\nsums for Yukawa potentials. As a conclusion to this work : Lekner sums should\nnot be used for quasi-two dimensional systems with Yukawa interaction\npotentials.",
        "positive": "Aging-Induced Dynamics for Statically Indeterminate System: Statically indeterminate systems are experimentally demonstrated to be in\nfact dynamical at the microscopic scale. Take the classic ladder-wall problem,\nfor instance. Depending on the Young's modulus of the wall, it may take up to\ntwenty minutes before its weight saturates. This finding is shown to be shared\nby other statically indeterminate systems, such as a granule silo and a beam\nwith three support points. We believe that the aging effect is responsible for\nthis surprising phenomenon because it can be correlated with the evolution of\nmicroscopic contact area with the wall and floor. Finally, a heuristic and\nsimple method is introduced that can uniquely determine and analytically solve\nthe saturated weight without invoking detailed material properties."
    },
    {
        "anchor": "Effective tension and fluctuations in active membranes: We calculate the fluctuation spectrum of the shape of a lipid vesicle or cell\nexposed to a nonthermal source of noise. In particular we take into account\nconstraints on the membrane area and the volume of fluid that it encapsulates\nwhen obtaining expressions for the dependency of the membrane tension on the\nnoise. We then investigate three possible origins of the non-thermal noise\ntaken from the literature: A direct force, which models an external medium\npushing on the membrane. A curvature force, which models a fluctuating\nspontaneous curvature, and a permeation force coming from an active transport\nof fluid through the membrane. For the direct force and curvature force cases,\nwe compare our results to existing experiments on active membranes.",
        "positive": "Dispersing Nanoparticles in a Polymer Film via Solvent Evaporation: Large scale molecular dynamics simulations are used to study the dispersion\nof nanoparticles (NPs) in a polymer film during solvent evaporation. As the\nsolvent evaporates, a dense polymer-rich skin layer forms at the liquid/vapor\ninterface, which is either NP rich or poor depending on the strength of the\nNP/polymer interaction. When the NPs are strongly wet by the polymer, the NPs\naccumulate at the interface and form layers. However when the NPs are only\npartially wet by the polymer, most NPs are uniformly distributed in the bulk of\nthe polymer film with the dense skin layer serving as a barrier to prevent the\nNPs from moving to the interface. Our results point to a possible route to\nemploy less favorable NP/polymer interactions and fast solvent evaporation to\nuniformly disperse NPs in a polymer film, contrary to the common belief that\nstrong NP/polymer attractions are needed to make NPs well dispersed in polymer\nnanocomposites."
    },
    {
        "anchor": "Structure of Polymer Brushes in Cylindrical Tubes: A Molecular Dynamics\n  Simulation: Molecular Dynamics simulations of a coarse-grained bead-spring model of\nflexible macromolecules tethered with one end to the surface of a cylindrical\npore are presented. Chain length $N$ and grafting density $\\sigma$ are varied\nover a wide range and the crossover from ``mushroom'' to ``brush'' behavior is\nstudied for three pore diameters. The monomer density profile and the\ndistribution of the free chain ends are computed and compared to the\ncorresponding model of polymer brushes at flat substrates. It is found that\nthere exists a regime of $N$ and $\\sigma$ for large enough pore diameter where\nthe brush height in the pore exceeds the brush height on the flat substrate,\nwhile for large enough $N$ and $\\sigma$ (and small enough pore diameters) the\nopposite behavior occurs, i.e. the brush is compressed by confinement. These\nfindings are used to discuss the corresponding theories on polymer brushes at\nconcave substrates.",
        "positive": "Relation between the contact force and local geometry for an elastic\n  curve under general surface confinement: Confinement of filamentary objects is ubiquitous in numerous biological,\nmedical, and engineering scenarios. Quantitatively determining the mechanical\ninteraction between flexible filaments and surface confinement is particularly\nchallenging due to the unknown contact force induced by elasticity interacting\nwith geometric constraints. Here, we consider a simplified model of confined\nfilamentary object: an elastic curve under surface confinement. Local force and\nmoment balance equation incorporating the role of contact is utilized to derive\nthe contact force exerted by surface on the confined elastic curve. It reveals\nthe relation between contact force and local geometry at balanced state and\nprovides a route to obtain the contact force from local confined geometry\ndirectly. Examples are provided to illustrate how to calculate contact force\nfrom obtained geometries. We believe that our results contribute to future\nefforts in the mechanics of filamentary objects under surface confinement."
    },
    {
        "anchor": "Correlation Functions for an Elastic String in a Random Potential:\n  Instanton Approach: We develop an instanton technique for calculations of correlation functions\ncharacterizing statistical behavior of the elastic string in disordered media\nand apply the proposed approach to correlations of string free energies\ncorresponding to different low-lying metastable positions. We find high-energy\ntails of correlation functions for the case of long-range disorder (the\ndisorder correlation length well exceeds the characteristic distance between\nthe sequential string positions) and short-range disorder with the correlation\nlength much smaller then the characteristic string displacements. The former\ncase refers to energy distributions and correlations on the distances below the\nLarkin correlation length, while the latter describes correlations on the large\nspatial scales relevant for the creep dynamics.",
        "positive": "On Mechanical Behavior of Elastomeric Networks: Effects of Random Porous\n  Microstructure: An assumption in micromechanical analysis of polymers is that the\nconstitutive polymeric media is non-porous. Non-porosity of media, however, is\nmerely a simplifying assumption. In this paper, we neglect this assumption and\nstudied polymer networks with a different porosity volume fraction. A random\nmorphology description function is used to model the porosity of the network\nand nonlinear finite element analyses are conducted to perform structural\nanalysis of porous polymer networks. The results show that the porosity effect\nis significant in mechanical behavior of polymer networks and may increase the\nmaximum Von-Mises stress drastically."
    },
    {
        "anchor": "Effect of ions on confined near-critical binary aqueous mixture: Near-critical binary mixtures containing ions and confined between two\ncharged and selective surfaces are studied within a Landau-Ginzburg theory\nextended to include electrostatic interactions. Charge density profiles and the\neffective interactions between the confining surfaces are calculated in the\ncase of chemical preference of ions for one of the solvent components. Close to\nthe consolute point of the binary solvent, the preferential solubility of ions\nleads to the modification of the charge density profiles in respect to the ones\nobtained from the Debye-H\\\"uckel theory. As a result, the electrostatic\ncontribution to the effective potential between the charged surface can exhibit\nan attractive well. Our calculations are based on the approximation scheme\nvalid if the bulk correlation length of a solvent is much larger than the Debye\nscreening length; in this critical regime the effect of charge on the\nconcentration profiles of the solvent is subdominant. Such conditions are met\nin the recent measurements of the effective forces acting between a substrate\nand a spherical colloidal particle immersed in the near-critical water-lutidine\nmixture [Nature V. 451, 172 (2008)]. Our analytical results are in a\nquantitative agreement with the experimental ones.",
        "positive": "Hydrodynamic spin-orbit coupling in asynchronous optically driven\n  micro-rotors: Vortical flows of rotating particles describe interactions ranging from\nmolecular machines to atmospheric dynamics. Yet to date, direct observation of\nthe hydrodynamic coupling between artificial micro-rotors has been restricted\nby the details of the chosen drive, either through synchronization (using\nexternal magnetic fields) or confinement (using optical tweezers). Here we\npresent a new active system that illuminates the interplay of rotation and\ntranslation in free rotors. We developed a non-tweezing circularly polarized\nbeam that simultaneously rotates hundreds of silica-coated birefringent\ncolloids. The particles rotate asynchronously in the optical torque field while\nfreely diffusing in the plane. We observe that neighboring particles orbit each\nother with an angular velocity that depends on their spins. We derive an\nanalytical model in the Stokes limit for pairs of spheres that quantitatively\nexplains the observed dynamics. We then find that the geometrical nature of the\nlow Reynolds fluid results in a universal hydrodynamic spin-orbit coupling. Our\nfindings are of significance for the understanding and development of\nfar-from-equilibrium materials."
    },
    {
        "anchor": "New criteria for cluster identification in continuum systems: Two new criteria, that involve the microscopic dynamics of the system, are\nproposed for the identification of clusters in continuum systems. The first one\nconsiders a residence time in the definition of the bond between pairs of\nparticles, whereas the second one uses a life time in the definition of an\naggregate. Because of the qualitative features of the clusters yielded by the\ncriteria we call them chemical and physical clusters, respectively. Molecular\ndynamics results for a Lennard-Jones system and general connectivity theories\nare presented.",
        "positive": "Ray Optics for Gliders: Control of self-propelled particles is central to the development of many\nmicrorobotic technologies, from dynamically reconfigurable materials to\nadvanced lab-on-a-chip systems. However, there are few physical principles by\nwhich particle trajectories can be specified and can be used to generate a wide\nrange of behaviors. Within the field of ray optics, a single principle for\ncontrolling the trajectory of light -- Snell's law -- yields an intuitive\nframework for engineering a broad range of devices, from microscopes to cameras\nand telescopes. Here we show that the motion of self-propelled particles\ngliding across a resistance discontinuity is governed by a variant of Snell's\nlaw, and develop a corresponding ray optics for gliders. Just as the ratio of\nrefractive indexes sets the path of a light ray, the ratio of resistance\ncoefficients is shown to determine the trajectories of gliders. The magnitude\nof refraction depends on the glider's shape, in particular its aspect ratio,\nwhich serves as an analog to the wavelength of light. This enables the demixing\nof a polymorphic, many-shaped, beam of gliders into distinct monomorphic,\nsingle-shaped, beams through a friction prism. In turn, beams of monomorphic\ngliders can be focused by spherical and gradient friction lenses.\nAlternatively, the critical angle for total internal reflection can be used to\ncreate shape-selective glider traps. Overall our work suggests that furthering\nthe analogy between light and microscopic gliders will result in a wide range\nof new devices for sorting, concentrating, and analyzing self-propelled\nparticles."
    },
    {
        "anchor": "Crossover of aging dynamics in polymer glass: from cumulative aging to\n  non-cumulative aging: The aging behavior of polymer glass, poly(methyl methacrylate), has been\ninvestigated through the measurement of ac dielectric susceptibility ata fixed\nfrequency after a temperature shift $\\Delta T$ ($\\le $ 20 K)between two\ntemperatures, $T_1$ and $T_2$. A crossover from cumulative aging to\nnon-cumulative aging could be observed with increasing $\\Delta T$ using a twin\ntemperature ($T$-) shift measurement. Based on a growth law of a dynamical\ncoherent length given by activated dynamics, we obtained a unique coherent\nlength for positive and negative $T$-shifts. The possibility of the existence\nof temperature chaos in polymer glasses is discussed.",
        "positive": "Isostaticity and the solidification of semiflexible polymer melts: Using molecular dynamics simulations of a tangent-soft-sphere bead-spring\npolymer model, we examine the degree to which semiflexible polymer melts\nsolidify at isostaticity. Flexible and stiff chains crystallize when they are\nisostatic as defined by appropriate degree-of-freedom-counting arguments.\nSemiflexible chains also solidify when isostatic if a generalized isostaticity\ncriterion that accounts for the slow freezing out of configurational freedom as\nchain stiffness increases is employed. The dependence of the average\ncoordination number at solidification $Z(T_s)$ on chains' characteristic ratio\n$C_\\infty$ has the same functional form [$Z \\simeq a - b\\ln(C_\\infty)$] as the\ndependence of the average coordination number at jamming $Z(\\phi_J)$ on\n$C_\\infty$ in athermal systems, suggesting that jamming-related phenomena play\na significant role in thermal polymer solidification."
    },
    {
        "anchor": "Ab initio investigation of intermolecular interactions in solid benzene: A computational strategy for the evaluation of the crystal lattice constants\nand cohesive energy of the weakly bound molecular solids is proposed. The\nstrategy is based on the high level ab initio coupled-cluster determination of\nthe pairwise additive contribution to the interaction energy. The\nzero-point-energy correction and non-additive contributions to the interaction\nenergy are treated using density functional methods. The experimental crystal\nlattice constants of the solid benzene are reproduced, and the value of 480\nmeV/molecule is calculated for its cohesive energy.",
        "positive": "Soft interactions modify the diffusive dynamics of polymer-grafted\n  nanoparticles in solutions of free polymer: We examine the dynamics of silica particles grafted with high molecular\nweight polystyrene suspended in semidilute solutions of chemically similar\nlinear polymer using x-ray photon correlation spectroscopy. The particle\ndynamics decouple from the bulk viscosity despite their large hydrodynamic size\nand instead experience an effective viscosity that depends on the molecular\nweight of the free polymer chains. Unlike for hard sphere nanoparticles in\nsemidilute polymer solutions, the diffusivities of the polymer-grafted\nnanoparticles do not collapse onto a master curve as a function of normalized\nlength scales. These results suggest that the soft interaction potential\nbetween polymer-grafted nanoparticles and free polymer allows polymer-grafted\nnanoparticles to diffuse faster than predicted based on bulk rheology and\nmodifies the coupling between grafted particle dynamics and the relaxations of\nthe surrounding free polymer."
    },
    {
        "anchor": "Length segregation in mixtures of spherocylinders induced by imposed\n  topological defects: We explore length segregation in binary mixtures of spherocylinders of\nlengths $L_1$ and $L_2$ with the same diameter $D$ which are tangentially\nconfined on a spherical surface of radius $R$. The orientation of\nspherocylinders is constrained along an externally imposed direction field on\nthe sphere which is either along the longitude or the latitude lines of the\nsphere. In both situations, integer orientational defects at the poles are\nimposed. We show that these topological defects induce a complex segregation\npicture also depending on the length ratio factor $\\gamma$=$L_2/L_1$ and the\ntotal packing fraction $\\eta$ of the spherocylinders. When the binary mixture\nis aligned along longitudinal lines of the sphere, shorter rods tend to\naccumulate at the topological defects of the polar caps whereas longer rods\noccupy central equatorial area of the spherical surface. In the reverse case of\nlatitude ordering, a state can emerge where longer rods are predominantly both\nin the cap and in the equatorial areas and shorter rods are localized in\nbetween. As a reference situation, we consider a defect-free situation in the\nflat plane and do not find any length segregation there at similar $\\gamma$ and\n$\\eta$, hence the segregation is purely induced by the imposed topological\ndefects. It is also revealed that the shorter rods at $\\gamma$=4 and $\\eta\n\\ge$0.5 act as obstacles to the rotational relaxation of the longer rods when\nall orientational constraints are released.",
        "positive": "Phase diagram and effective shape of semi-flexible colloidal rods and\n  biopolymers: We study suspensions of semi-flexible colloidal rods and biopolymers using an\nOnsager-type second-virial functional for a segmented-chain model. For\nsuspensions of thin and thick fd virus particles we calculate phase diagrams in\nquantitative agreement with experimental observations, and we find their\neffective state-point dependent shape to be much shorter and thicker than the\nactual shape. We also calculate the stretching of worm-like micelles in a host\nfd virus solution, again finding agreement with experiments. For both systems,\nour results show that the fd virus stiffness can play a key role in system\nbehavior."
    },
    {
        "anchor": "Structure formation in binary mixtures of surfactants: vesicle\n  opening-up to bicelles and octopus-like micelles: Micelle formation in binary mixtures of surfactants is studied using a\ncoarse-grained molecular simulation. When a vesicle composed of lipid and\ndetergent types of molecules is ruptured, a disk-shaped micelle, the bicelle,\nis typically formed. It is found that cup-shaped vesicles and bicelles\nconnected with worm-like micelles are also formed depending on the surfactant\nratio and critical micelle concentration. The obtained octopus shape of\nmicelles agree with those observed in the cryo-TEM images reported in [S. Jain\nand F. S. Bates, Macromol. 37, 1511 (2004).]. Two types of connection\nstructures between the worm-like micelles and the bicelles are revealed.",
        "positive": "Crystallization of self-propelled hard-discs : a new scenario: We experimentally study the crystallization of a monolayer of vibrated discs\nwith a built-in polar asymmetry, a model system of active liquids, and contrast\nit with that of vibrated isotropic discs. Increasing the packing fraction\n$\\phi$, the quasi-continuous crystallization reported for isotropic discs is\nreplaced by a transition, or a crossover towards a \"self-melting\" crystal.\nIncreasing the packing fraction from the liquid phase, clusters of dense\nhexagonally-ordered packed discs spontaneously form, melt, split and merge\nleading to a highly intermittent and heterogeneous dynamics. The resulting\nsteady state cluster size distribution decreases monotonically. For packing\nfraction larger than $\\phi^*$, a few large clusters span the system size and\nthe cluster size distribution becomes non monotonic, the transition being\nsigned by a power-law. The system is however never dynamically arrested. The\nclusters permanently melt from place to place forming droplets of active liquid\nwhich rapidly propagate across the system. This state of affair remains up to\nthe highest possible packing fraction questioning the stability of the crystal\nfor active discs, unless at ordered close packing."
    },
    {
        "anchor": "Rejuvenating the structure and rheological properties of silica\n  nanocomposites based on natural rubber: The antagonistic effect of processing and thermal annealing on both the\nfiller structure and the polymer matrix is explored in polymer nanocomposites\nbased on natural rubber with precipitated silica incorporated by coagulation\nfrom aqueous suspension followed by roll-milling. Their structure and linear\nand non-linear rheology have been studied, with a particular emphasis on the\neffect of high temperature thermal treatment and the number of milling passes.\nSmall-angle X-ray scattering intensities show that the silica is organized in\nsmall, unbreakable aggregates containing ca. 50 primary nanoparticles, which\nare reorganized on a larger scale in filler networks percolating at the highest\nsilica contents. As expected, the filler network structure is found to be\nsensitive to milling, more milling inducing rupture, as evidenced by the\ndecreasing Payne effect. After thermal treatment, the nanocomposite structure\nis found to be rejuvenated, erasing the effect of the previous milling on the\nlow-strain modulus. In parallel, the dynamics of the samples described by the\nrheology or the calorimetric glass-transition temperature remain unchanged,\nwhereas the natural latex polymer network structure is modified by milling\ntowards a more fluid-like rheology, and cannot be recovered.",
        "positive": "Divergence of Viscosity in Jammed Granular Materials: A Theoretical\n  Approach: A theory for jammed granular materials is developed with the aid of a\nnonequilibrium steady-state distribution function. The approximate\nnonequilibrium steady-state distribution function is explicitly given in the\nweak dissipation regime by means of the relaxation time. The theory\nquantitatively agrees with the results of the molecular dynamics simulation on\nthe critical behavior of the viscosity below the jamming point without\nintroducing any fitting parameter."
    },
    {
        "anchor": "Groundstates of SU(2)-Symmetric Confined Bose Gas: Trap for a\n  Schr\u00f6dinger Cat: Conservation of the total isotopic spin S of a two-component Bose gas-like\n$^{87}$Rb-has a dramatic impact on the structure of the ground state. In the\ncase when S is much smaller than the total number of particles N, the\ncondensation of each of the two components occurs into two single-particle\nmodes. The quantum wavefunction of such a groundstate is a Schr\\\"odinger Cat-a\nsuperposition of the phase separated classical condensates, the most \"probable\"\nstate in the superposition corresponding to the classical groundstate in the\nsector of given N and S. After measurement of the spatial distribution of the\ndensities of the two components, the Cat collapses into one of the classical\ncondensate states.",
        "positive": "Size, shape and diffusivity of a single Debye-H\u00fcckel polyelectrolyte\n  chain in solution: Brownian dynamics simulations of a coarse-grained bead-spring chain model,\nwith Debye-H\\\"uckel electrostatic interactions between the beads, are used to\ndetermine the root-mean-square end-to-end vector, the radius of gyration, and\nvarious shape functions (defined in terms of eigenvalues of the radius of\ngyration tensor) of a weakly-charged polyelectrolyte chain in solution, in the\nlimit of low polymer concentration. The long-time diffusivity is calculated\nfrom the mean square displacement of the centre of mass of the chain, with\nhydrodynamic interactions taken into account through the incorporation of the\nRotne-Prager-Yamakawa tensor. Simulation results are interpreted in the light\nof the OSFKK blob scaling theory (R. Everaers, A. Milchev, and V. Yamakov, Eur.\nPhys. J. E 8, 3 (2002)) which predicts that all solution properties are\ndetermined by just two scaling variables--the number of electrostatic blobs\n$X$, and the reduced Debye screening length, $Y$. We identify three broad\nregimes, the ideal chain regime at small values of $Y$, the blob-pole regime at\nlarge values of $Y$, and the crossover regime at intermediate values of $Y$,\nwithin which the mean size, shape, and diffusivity exhibit characteristic\nbehaviours. In particular, when simulation results are recast in terms of blob\nscaling variables, universal behaviour independent of the choice of bead-spring\nchain parameters, and the number of blobs $X$, is observed in the ideal chain\nregime and in much of the crossover regime, while the existence of logarithmic\ncorrections to scaling in the blob-pole regime leads to non-universal\nbehaviour."
    },
    {
        "anchor": "Dynamic Scaling of Polymer Gels Comprising Nanoparticles: We present dynamic light scattering (DLS) measurements of soft\npolymethyl-methacrylate (PMMA) and polyacrylamide(PA) polymer gels prepared\nwith trapped bodies (latex spheres or maghemite nanoparticles). We show that\nthe anomalous diffusivity of the trapped particles can be analyzed in terms of\na fractal Gaussian network gel model for the entire time range probed by DLS\ntechnique. This model is a generalization of the Rouse model for linear chains\nextended for structures with power law network connectivity scaling, which\nincludes both percolating and uniform bulk gel limits. For a dilute dispersion\nof strongly scattering particles trapped in a gel, the scattered electric field\ncorrelation function at small wavevector ideally probes self-diffusion of gel\nportions imprisoning the particles. Our results show that the time-dependent\ndiffusion coefficients calculated from the correlation functions change from a\nfree diffusion regime at short times to an anomalous sub-diffusive regime at\nlong times (increasingly arrested displacement). The characteristic time of\ntransition between these regimes depends on scattering vector as $\\sim q^{-2}$\nwhile the time decay power exponent tends to the value expected for a bulk\nnetwork at small $q$. The diffusion curves for all scattering vectors and all\nsamples were scaled to a single master curve.",
        "positive": "Orientational ordering in hard rectangles: The role of three-body\n  correlations: We investigate the effect of three-body correlations on the phase behavior of\nhard rectangle two-dimensional fluids. The third virial coefficient, $B_3$, is\nincorporated via an equation of state that recovers scaled particle theory for\nparallel hard rectangles. This coefficient, a functional of the orientational\ndistribution function, is calculated by Monte Carlo integration, using an\naccurate parameterized distribution function, for various particle aspect\nratios in the range 1-25. A bifurcation analysis of the free energy calculated\nfrom the obtained equation of state is applied to find the isotropic\n(I)-uniaxial nematic (N$_u$) and isotropic-tetratic nematic (N$_t$) spinodals\nand to study the order of these phase transitions. We find that the relative\nstability of the N$_t$ phase with respect to the isotropic phase is enhanced by\nthe introduction of $B_3$. Finally, we have calculated the complete phase\ndiagram using a variational procedure and compared the results with those\nobtained from scaled particle theory and with Monte Carlo simulations carried\nout for hard rectangles with various aspect ratios. The predictions of our\nproposed equation of state as regards the transition densities between the\nisotropic and orientationally ordered phases for small aspect ratios are in\nfair agreement with simulations. Also, the critical aspect ratio below which\nthe N$_t$ phase becomes stable is predicted to increase due to three-body\ncorrelations, although the corresponding value is underestimated with respect\nto simulation."
    },
    {
        "anchor": "Softness dependence of the Anomalies for the Continuous Shouldered Well\n  potential: By molecular dynamic simulations we study a system of particles interacting\nthrough a continuous isotropic pairwise core-softened potential consisting of a\nrepulsive shoulder and an attractive well. The model displays a phase diagram\nwith three fluid phases, a gas-liquid critical point, a liquid-liquid critical\npoint, and anomalies in density, diffusion and structure. The hierarchy of the\nanomalies is the same as for water. We study the effect on the anomalies of\nvarying the softness of the potential. We find that, making the soft-core\nsteeper, the regions of density and diffusion anomalies contract in the T -\n{\\rho} plane, while the region of structural anomaly is weakly affected.\nTherefore, a liquid can have anomalous structural behavior without density or\ndiffusion anomalies. We show that, by considering as effective distances those\ncorresponding to the maxima of the first two peaks of the radial distribution\nfunction g(r) in the high-density liquid, we can generalize to continuous\ntwo-scales potentials a criterion for the occurrence of the anomalies of\ndensity and diffusion, originally proposed for discontinuous potentials. We\nobserve that the knowledge of the structural behavior within the first two\ncoordination shells of the liquid is not enough to establish the occurrence of\nthe anomalies. By introducing the density derivative of the the cumulative\norder integral of the excess entropy we show that the anomalous behavior is\nregulated by the structural order at distances as large as the fourth\ncoordination shell. By comparing the results for different softness of the\npotential, we conclude that the disappearing of the density and diffusion\nanomalies for the steeper potentials is due to a more structured short-range\norder. All these results increase our understanding on how, knowing the\ninteraction potential, we can evaluate the possible presence of anomalies for a\nliquid.",
        "positive": "A Cyclical Route Linking Fundamental Mechanism and AI Algorithm: An\n  Example from Poisson's Ratio in Amorphous Networks: \"AI for science\" is widely recognized as a future trend in the development of\nscientific research. Currently, although machine learning algorithms have\nplayed a crucial role in scientific research with numerous successful cases,\nrelatively few instances exist where AI assists researchers in uncovering the\nunderlying physical mechanisms behind a certain phenomenon and subsequently\nusing that mechanism to improve machine learning algorithms' efficiency. This\narticle uses the investigation into the relationship between extreme Poisson's\nratio values and the structure of amorphous networks as a case study to\nillustrate how machine learning methods can assist in revealing underlying\nphysical mechanisms. Upon recognizing that the Poisson's ratio relies on the\nlow-frequency vibrational modes of dynamical matrix, we can then employ a\nconvolutional neural network, trained on the dynamical matrix instead of\ntraditional image recognition, to predict the Poisson's ratio of amorphous\nnetworks with a much higher efficiency. Through this example, we aim to\nshowcase the role that artificial intelligence can play in revealing\nfundamental physical mechanisms, which subsequently improves the machine\nlearning algorithms significantly."
    },
    {
        "anchor": "On the correlation between fragility and stretching in glassforming\n  liquids: We study the pressure and temperature dependences of the dielectric\nrelaxation of two molecular glassforming liquids, dibutyl phtalate and\nm-toluidine. We focus on two characteristics of the slowing down of relaxation,\nthe fragility associated with the temperature dependence and the stretching\ncharacterizing the relaxation function. We combine our data with data from the\nliterature to revisit the proposed correlation between these two quantities. We\ndo this in light of constraints that we suggest to put on the search for\nempirical correlations among properties of glassformers. In particular, argue\nthat a meaningful correlation is to be looked for between stretching and\nisochoric fragility, as both seem to be constant under isochronic conditions\nand thereby reflect the intrinsic effect of temperature.",
        "positive": "Locomotion and transport in a hexatic liquid crystal: The swimming behavior of bacteria and other microorganisms is sensitive to\nthe physical properties of the fluid in which they swim. Mucus, biofilms, and\nartificial liquid-crystalline solutions are all examples of fluids with some\ndegree of anisotropy that are also commonly encountered by bacteria. In this\narticle, we study how liquid-crystalline order affects the swimming behavior of\na model swimmer. The swimmer is a one-dimensional version of G. I. Taylor's\nswimming sheet: an infinite line undulating with small-amplitude transverse or\nlongitudinal traveling waves. The fluid is a two-dimensional hexatic\nliquid-crystalline film. We calculate the power dissipated, swimming speed, and\nflux of fluid entrained as a function of the swimmer's waveform as well as\nproperties of the hexatic film, such as the rotational and shear viscosity, the\nFrank elastic constant, and the anchoring strength. The departure from\nisotropic behavior is greatest for large rotational viscosity and weak\nanchoring boundary conditions on the orientational order at the swimmer\nsurface. We even find that if the rotational viscosity is large enough, the\ntransverse-wave swimmer moves in the opposite direction relative to a swimmer\nin an isotropic fluid."
    },
    {
        "anchor": "The Geometry of the Vapor Layer Under a Leidenfrost Drop: In the Leidenfrost effect, liquid drops deposited on a hot surface levitate\non a thin vapor cushion fed by evaporation of the liquid. This vapor layer\nforms a concave depression in the drop interface. Using laser-light\ninterference coupled to high-speed imaging, we measured the radius, curvature,\nand height of the vapor pocket, as well as non-axisymmetric fluctuations of the\ninterface for water drops at different temperatures. The geometry of the vapor\npocket depends primarily on the drop size and not on the substrate temperature.",
        "positive": "Rich polymorphism of a rod-like liquid crystal (8CB) confined in two\n  types of unidirectional nanopores: We present a neutron and X-rays scattering study of the phase transitions of\n4-n-octyl-4'-cyanobiphenyl (8CB) confined in unidirectional nanopores of porous\nalumina and porous silicon (PSi) membranes with an average diameter of 30 nm.\nSpatial confinement reveals a rich polymorphism, with at least four different\nlow temperature phases in addition to the smectic A phase. The structural study\nas a function of thermal treatments and conditions of spatial confinement\nallows us to get insights into the formation of these phases and their relative\nstability. It gives the first description of the complete phase behavior of 8CB\nconfined in PSi and provides a direct comparison with results obtained in bulk\nconditions and in similar geometric conditions of confinement but with reduced\nquenched disorder effects using alumina anopore membranes"
    },
    {
        "anchor": "Crossover behavior in failure avalanches: Composite materials, with statistically distributed threshold for breakdown\nof individual elements, are considered. During the failure process of such\nmaterials under external stress (load or voltage), avalanches consisting of\nsimultaneous rupture of several elements occur, with a distribution $D(\\Delta)$\nof the magnitude $\\Delta$ of such avalanches. The distribution is typically a\npower law $D(\\Delta)\\propto\\Delta^{-\\xi}$. For the systems we study here, a\ncrossover behavior is seen between two power laws, with a small exponent $\\xi$\nin the vicinity of complete breakdown and a larger exponent $\\xi$ for failures\naway from the breakdown point. We demonstrate this analytically for bundles of\nmany fibers where the load is uniformly distributed among the surviving fibers.\nIn this case $\\xi=3/2$ near the breakdown point and $\\xi=5/2$ away from it. The\nlatter is known to be the generic behavior. This crossover is a signal of\nimminent catastrophic failure of the material. Near the breakdown point,\navalanche statistics show nontrivial finite size scaling. We observe similar\ncrossover behavior in a network of electric fuses, and find $\\xi=2$ near the\ncatastrophic failure and $\\xi=3$ away from it. For this fuse model power\ndissipation avalanches show a similar crossover near breakdown.",
        "positive": "From concentration profiles to polymer osmotic equations of state: We show that equilibrium monomer and centre-of-mass concentration profiles of\nlattice polymers in a gravitational field, computed by Monte-Carlo simulations,\nprovide an accurate and efficient road to the osmotic equation-of-state of\npolymer solutions, via a straightforward application of the hydrostatic\nequilibrium condition. The method yields the full equation of state over a wide\nrange of concentrations from a single simulation, and does not suffer from\nsignificant finite size effects. It has been applied to self-avoiding walk\npolymer chains with nearest neighbour monomer attractions, from the good\nsolvent to the theta solvent regimes. The consistency of the method has been\ncarefully checked by varying the strength of the gravitational field."
    },
    {
        "anchor": "Self-assembling two-dimensional quasicrystals in simple systems of\n  monodisperse soft-core disks: In previous approaches to form quasicrystals, multiple competing length\nscales involved in particle size, shape or interaction potential are believed\nto be necessary. It is unexpected that quasicrystals can be self-assembled by\nmonodisperse, isotropic particles interacting via a simple potential without\nmultiple length scales. Here we report the surprising finding of the\nself-assembly of such quasicrystals in two dimensional systems of soft-core\ndisks interacting via repulsions. We find not only dodecagonal but also\noctagonal quasicrystals, which have not been found yet in soft quasicrystals.\nIn the self-assembly of such unexpected quasicrystals, particles tend to form\npentagons, which are essential elements to form the quasicrystalline order. Our\nfindings pave an unexpected and simple way to form quasicrystals and pose a new\nchallenge for theoretical understanding of quasicrystals.",
        "positive": "Critical behavior of active Brownian particles: We study active Brownian particles as a paradigm for genuine non-equilibrium\nphase transitions. Access to the critical point in computer simulations is\nobstructed by the fact that the density is conserved. We propose a modification\nof sampling finite-size fluctuations and successfully test this method for the\n2D Ising model. Using this model allows us to determine accurately the critical\npoint of two dimensional active Brownian particles at\n$\\text{Pe}_{\\text{cr}}=40(2)$, $\\phi_{\\text{cr}}=0.597(3)$. Based on this\nestimate, we study the corresponding critical exponents $\\beta$, $\\gamma/\\nu$,\nand $\\nu$. Our results are incompatible with the 2D-Ising exponents, thus\nraising the question whether there exists a corresponding non-equilibrium\nuniversality class."
    },
    {
        "anchor": "Molecular velocity auto-correlation of simple liquids observed by NMR\n  MGSE method: The velocity auto-correlation spectra of simple liquids obtained by the NMR\nmethod of modulated gradient spin echo show features in the low frequency range\nup to a few kHz, which can be explained reasonably well by a $t^{-3/2}$ long\ntime tail decay only for non-polar liquid toluene, while the spectra of polar\nliquids, such as ethanol, water and glycerol, are more congruent with the model\nof diffusion of particles temporarily trapped in potential wells created by\ntheir neighbors. As the method provides the spectrum averaged over ensemble of\nparticle trajectories, the initial non-exponential decay of spin echoes is\nattributed to a spatial heterogeneity of molecular motion in a bulk of liquid,\nreflected in distribution of the echo decays for short trajectories. While at\nlonger time intervals, and thus with longer trajectories, heterogeneity is\naveraged out, giving rise to a spectrum which is explained as a combination of\nmolecular self-diffusion and eddy diffusion within the vortexes of hydrodynamic\nfluctuations.",
        "positive": "Stokes Law at Molecular Length Scales: Effects of Intermolecular\n  Interactions and Linear Response Theory: The celebrated Stokes Law (SL) of hydrodynamics predicts that the velocity of\na particle pulled through a liquid by an external force, Fex, is directly\nproportional to the force and inversely proportional to the friction {\\zeta}\nacted by the medium on the particle. We investigate the range of validity of\nStokes Law at molecular length scales by employing computer simulations to\ncalculate friction by pulling a tagged particle with a constant force. We thus\ncalculate friction for two model interaction potentials, Lennard-Jones, and\nsoft sphere, for several particle sizes, ranging from radius (a) smaller than\nthe solvent particles to three times larger. We next obtain friction from\ndiffusion (D) by using Einstein's relation between diffusion and friction\n{\\zeta} in an unperturbed liquid. We find, to our surprise, a quantitative\nagreement between the two at a small-to-intermediate pulling force regime for\nall the sizes studied. The Law does break down at a large pulling force beyond\na threshold value. Importantly, the range of validity of Stokes' scheme to\nobtain friction increases substantially if we turn off the attractive part of\nthe interaction potential. Additionally, we calculate the viscosity ({\\eta}) of\nthe unperturbed liquid and find a good agreement with the Stokes-Einstein\nrelation {\\zeta}=C{\\eta}a for the viscosity dependence with a value of C close\nto 5 {\\pi}, that is intermediate between the slip and stick boundary condition."
    },
    {
        "anchor": "Universality of Block Copolymer Melts: Simulations of five different coarse-grained models of symmetric diblock\ncopolymer melts are compared to demonstrate a universal (i.e.,\nmodel-independent) dependence of the free energy on the invariant degree of\npolymerization $\\overline{N}$, and to study universal properties of the\norder-disorder transition (ODT). The ODT appears to exhibit two regimes:\nSystems of very long chains ($\\overline{N} \\gtrsim 10^{4}$) are well described\nby the Fredrickson-Helfand theory, which assumes weak segregation near the ODT.\nSystems of smaller but experimentally relevant values, $\\overline{N} \\lesssim\n10^4$, undergo a transition between strongly segregated disordered and lamellar\nphases that, though universal, is not adequately described by any existing\ntheory.",
        "positive": "Absence of logarithmic attraction between colloids trapped at the\n  interface of droplets: We pinpoint and correct several mathematical errors in EPL 75(2006)978. As a\nconsequence, we conclude that there is no logarithmically varying interfacial\ndeformation, contrary to the claim in the EPL."
    },
    {
        "anchor": "Long range polarization attraction between two different likely charged\n  macroions: It is known that in a water solution with multivalent counterions (Z-ions),\ntwo likely charged macroions can attract each other due to correlations of\nZ-ions adsorbed on their surfaces. This \"correlation\" attraction is\nshort-ranged and decays exponentially with increasing distance between\nmacroions at characteristic distance A/2\\pi, where A is the average distance\nbetween Z-ions on the surfaces of macroions. In this work, we show that an\nadditional long range \"polarization\" attraction exists when the bare surface\ncharge densities of the two macroions have the same sign, but are different in\nabsolute values. The key idea is that with adsorbed Z-ions, two insulating\nmacroions can be considered as conductors with fixed but different electric\npotentials. Each potential is determined by the difference between the entropic\nbulk chemical potential of a Z-ion and its correlation chemical potential at\nthe surface of the macroion determined by its bare surface charge density. When\nthe two macroions are close enough, they get polarized in such a way that their\nadjacent spots form a charged capacitor, which leads to attraction. In a salt\nfree solution this polarization attractive force is long ranged: it decays as a\npower of the distance between the surfaces of two macroions, d. The\npolarization force decays slower than the van der Waals attraction and\ntherefore is much larger than it in a large range of distances. In the presence\nof large amount of monovalent salt, when A/2\\pi<< d<< r_s (r_s is the\nDebye-H\\\"{u}ckel screening radius), this force is still much stronger than the\nvan der Waals attraction and the correlation attraction mentioned above.",
        "positive": "The van der Waals idea of pseudo associations and the critical\n  compressibility factor: The dimensionless value of critical compressibility factor in the van der\nWaals theory of gas-liquid critical point is a universal constant, $Z_\\text{c}\n= 0.375$. Experimentally measured values of this quantity for simple fluids are\nconsiderably smaller than the theory prediction. Van der Waals once assumed\nthat this discrepancy can be removed by taking account of the impact of the\nmolecular pseudo-associations on the fluid criticality but he did not complete\na proper modification of his theory following up on this idea. The\ncommunication is devoted to the filling of this gap."
    },
    {
        "anchor": "Theory of Sol-Gel Transition in Thermoreversible Gels with due Regard\n  for Fundamental Role of Mesoscopic Cyclization Effects. I. Thermodynamic and\n  Structural Characteristics of Gel Phase: The sol-gel transition (SGT), upon which the infinite cluster (IC) of\nthermoreversibly bonded particles (gel fraction) appears against a background\nof a set of finite clusters (sol fraction), is first quantitatively considered\nwith due regard for large and complicated (mesoscopic) cycles inevitably\npresent in the IC. To this end we present a new approach based on a concept of\nthe monomer identity breaking and density functional description. We strictly\nderive, via a proper choice of basic structural units of the gel fraction, all\nstatements usually supposed to be just Flory (Stockmayer) assumptions. A\nfurther analysis of the IC structure reveals some new IC structural units\n(those involved into mesoscopic cycles) overlooked in both Flory and Stockmayer\napproaches and to be described by a new order parameter characteristic only of\nthe gel phase. As a result, the SGT is found to transform from a geometric\nphenomenon to a genuine 1st order phase transition always followed by a phase\nseparation into sol and gel phases. The free energy, total conversion, volume\nfractions of the gel fraction and dangling monomers as well as other structural\nquantities are calculated as functions of a reduced monomer density and\nanalyzed for all the existing models. The Flory approach is found to be\nsuperior to the Stockmayer-Tanaka one and satisfactorily describe some of the\ndense weak gel properties but fail (even qualitatively) in a quite extended\nvicinity of the SGT.",
        "positive": "Dynamics and Stress Relaxation of Bidisperse Polymer Melts with\n  Unentangled and Moderately Entangled Chains: Polydispersity is inevitable in industrially produced polymers. Established\ntheories of polymer dynamics and rheology, however, were mostly built on\nmonodisperse linear polymers. Dynamics of polydisperse polymers is yet to be\nfully explored -- especially how chains of different lengths affect the\ndynamics of one another in a mixture. This study explored the dynamics of\nbidisperse polymer melts using molecular dynamics and a bead-spring chain\nmodel. Binary mixtures between a moderately entangled long-chain species and an\nunentangled or marginally entangled short-chain species were investigated. We\nfound that adding short chains can significantly accelerate the dynamics of the\nlong chains by substantially lessening their extent of entanglement. Meanwhile,\nalthough introducing long chains also hinders the motion of the short chains,\nit does not qualitatively alter the nature of their dynamics -- unentangled\nshort chains still follow classical Rouse dynamics even in a matrix containing\nentangled chains. Detailed Rouse mode analysis was used to reveal the effects\nof entanglement at chain segments of different scales. Stress relaxation\nfollowing a step shear strain was also studied and semi-empirical mixing rules\nthat predict the linear viscoelasticity of polydisperse polymers based on that\nof monodisperse systems were evaluated with simulation results."
    },
    {
        "anchor": "Modeling the Relaxation of Polymer Glasses under Shear and Elongational\n  Loads: Glassy polymers show strain hardening: at constant extensional load, their\nflow first accelerates, then arrests. Recent experiments under such loading\nhave found this to be accompanied by a striking dip in the segmental relaxation\ntime. This can be explained by a minimal nonfactorable model combining\nflow-induced melting of a glass with the buildup of stress carried by strained\npolymers. Within this model, liquefaction of segmental motion permits strong\nflow that creates polymer-borne stress, slowing the deformation enough for the\nsegmental (or solvent) modes to then re-vitrify. Here we present new results\nfor the corresponding behavior under step-stress shear loading, to which very\nsimilar physics applies. To explain the unloading behavior in the extensional\ncase requires introduction of a crinkle factor describing a rapid loss of\nsegmental ordering. We discuss in more detail here the physics of this, which\nwe argue involves non-entropic contributions to the polymer stress, and which\nmight lead to some important differences between shear and elongation. We also\ndiscuss some fundamental and possibly testable issues concerning the physical\nmeaning of entropic elasticity in vitrified polymers. Finally we present new\nresults for the startup of steady shear flow, addressing the possible role of\ntransient shear banding.",
        "positive": "Analysis and correction of errors in nanoscale particle tracking using\n  the Single-pixel interior filling function (SPIFF) algorithm: Particle tracking, which is an essential tool in many fields of scientific\nresearch, uses algorithms that retrieve the centroid of tracked particles with\nsub-pixel accuracy. However, images in which the particles occupy a small\nnumber of pixels on the detector, are in close proximity to other particles or\nsuffer from background noise, show a systematic error in which the particle\nsub-pixel positions are biased towards the center of the pixel. This pixel\nlocking effect greatly reduces particle tracking accuracy. In this report, we\ndemonstrate the severity of these errors by tracking experimental (and\nsimulated) imaging data of optically trapped silver nanoparticles and single\nfluorescent proteins. We show that errors in interparticle separation, angle\nand mean square displacement are significantly reduced by applying the\ncorrective Single- pixel interior filling function (SPIFF) algorithm. Our work\ndemonstrates the potential ubiquity of such errors and the general\napplicability of SPIFF correction to many experimental fields."
    },
    {
        "anchor": "Mean field elastic moduli of a three-dimensional cell-based vertex model: The mechanics of a foam typically depends on the bubble geometry, topology,\nand the material at hand, be it metallic or polymeric, for example. While the\nfoam energy functional for each bubble is typically minimization of surface\narea for a given volume, biology provides us with a wealth of additional energy\nfunctionals, should one consider biological cells as a foam-like material.\nHere, we focus on a mean field approach to obtain the elastic moduli, within\nlinear response, for an ordered, three-dimensional vertex model using the\nspace-filling shape of a truncated octahedron and whose energy functional is\ncharacterized by a restoring surface area spring and a restoring volume spring.\nThe tuning of the three-dimensional shape index exhibits a rigidity transition\nvia a compatible-incompatible transition. Specifically, for smaller shape\nindices, both the target surface area and volume cannot be achieved, while\nbeyond some critical value of the three-dimensional shape index, they can be,\nresulting in a zero-energy state. As the elastic moduli depend on curvatures of\nthe energy when the system, we obtain these as well. In addition to\nanalytically determining the location of the transition in mean field, we find\nthat the rigidity transition and the elastic moduli depend on the\nparameterization of the cell shape with this effect being more pronounced in\nthree dimensions given the array of shapes that a polyhedron can take on (as\ncompared to a polygon). We also uncover nontrivial dependence on the\ndeformation protocol in which some deformations result in affine motion of the\nvertices, while others result in nonaffine motion. Such dependencies on the\nshape parameterization and deformation protocol give rise to a nontrivial shape\nlandscape and, therefore, nontrivial mechanical response even in the absence of\ntopology changes.",
        "positive": "Robust Molecular Computation by Active Mechanics: The living cell expends energetic and material resources to reliably process\ninformation from its environment. To do so, it utilises unreliable molecular\ncircuitry that is subject to thermal and other fluctuations. Here, we argue\nthat active, physical processes can provide error correcting mechanisms for\ninformation processing. We analyse a model in which fluctuating receptor\nactivation induces contractile stresses that recruit further receptors,\ndynamically controlling resource usage and accuracy. We show that this active\nscheme can outperform passive, static clusters (as formed, for instance, by\nprotein crosslinking). We consider simple binary environments, informative\ndecision trees, and chemical computations; in each case, active stresses serve\nto contextually build signalling platforms that dynamically suppress error and\nallows for robust cellular computation."
    },
    {
        "anchor": "On the contact conditions for the density and charge profiles in the\n  theory of electrical double layer: From planar to spherical and cylindrical\n  geometry: In this paper, starting from the Bogoliubov-Born-Green-Yvon equations of the\nliquid-state theory, we formulate two equivalent approaches for the calculation\nof the total density profile and of the charge density profile of ionic fluids\nnear nonplanar charged surfaces. In the framework of these approaches, we\nestablish exact conditions, that a particular point of these profiles should\nsatisfy, in the form of contact theorems. These contact theorems for the total\ndensity profile and the charge density profile are obtained by direct\nintegration of a system of equations derived from the\nBogoliubov-Born-Green-Yvon equations. The contact theorems for both profiles\nhave nonlocal character. It is shown that the contact value of the total\ndensity profile for uncharged surfaces is characterized by the bulk pressure\nand the surface tension. The contact theorems are applied to the cases of\nspherical and cylindrical surfaces. It is shown that the contact theorem for\nthe total density profile coincides with the recent results obtained by W.\nSilvester-Alcantara, D. Henderson and L.B. Bhuiyan Mol. Phys., 113, 3403, 2015",
        "positive": "Rouse Chains with Excluded Volume Interactions: Linear Viscoelasticity: Linear viscoelastic properties for a dilute polymer solution are predicted by\nmodeling the solution as a suspension of non-interacting bead-spring chains.\nThe present model, unlike the Rouse model, can describe the solution's\nrheological behavior even when the solvent quality is good, since excluded\nvolume effects are explicitly taken into account through a narrow Gaussian\nrepulsive potential between pairs of beads in a bead-spring chain. The use of\nthe narrow Gaussian potential, which tends to the more commonly used\ndelta-function repulsive potential in the limit of a width parameter \"d\" going\nto zero, enables the performance of Brownian dynamics simulations. The\nsimulations results, which describe the exact behavior of the model, indicate\nthat for chains of arbitrary but finite length, a delta-function potential\nleads to equilibrium and zero shear rate properties which are identical to the\npredictions of the Rouse model. On the other hand, a non-zero value of \"d\"\ngives rise to a prediction of swelling at equilibrium, and an increase in zero\nshear rate properties relative to their Rouse model values. The use of a\ndelta-function potential appears to be justified in the limit of infinite chain\nlength. The exact simulation results are compared with those obtained with an\napproximate solution which is based on the assumption that the non-equilibrium\nconfigurational distribution function is Gaussian. The Gaussian approximation\nis shown to be exact to first order in the strength of excluded volume\ninteraction, and is found to be accurate above a threshold value of \"d\", for\ngiven values of chain length and strength of excluded volume interaction."
    },
    {
        "anchor": "Glassiness, Rigidity and Jamming of Frictionless Soft Core Disks: The jamming of bi-disperse soft core disks is considered, using a variety of\ndifferent protocols to produce the jammed state. In agreement with other works,\nwe find that cooling and compression can lead to a broad range of jamming\npacking fractions $\\phi_J$, depending on cooling rate and initial\nconfiguration; the larger the degree of big particle clustering in the initial\nconfiguration, the larger will be the value of $\\phi_J$. In contrast, we find\nthat shearing disrupts particle clustering, leading to a much narrower range of\n$\\phi_J$ as the shear strain rate varies. In the limit of vanishingly small\nshear strain rate, we find a unique non-trivial value for the jamming density\nthat is independent of the initial system configuration. We conclude that shear\ndriven jamming is a unique and well defined critical point in the space of\nshear driven steady states. We clarify the relation between glassy behavior,\nrigidity and jamming in such systems and relate our results to recent\nexperiments.",
        "positive": "Polymer threadings and rigidity dictate the viscoelasticity and\n  nonlinear relaxation dynamics of entangled ring-linear blends and their\n  composites with rigid rod microtubules: Mixtures of polymers of varying topologies and stiffnesses display complex\nemergent rheological properties that often cannot be predicted from their\nsingle-component counterparts. For example, entangled blends of ring and linear\npolymers have been shown to exhibit enhanced shear thinning and viscosity, as\nwell as prolonged relaxation timescales, compared to pure solutions of rings or\nlinear chains. These emergent properties arise in part from the synergistic\nthreading of rings by linear polymers. Topology has also been shown to play an\nimportant role in composites of flexible (e.g., DNA) and stiff (e.g.,\nmicrotubules) polymers, whereby rings promote mixing while linear polymers\ninduce de-mixing and flocculation of stiff polymers, with these\ntopology-dependent interactions giving rise to highly distinct rheological\nsignatures. To shed light on these intriguing phenomena, we use optical\ntweezers microrheology to measure the linear and nonlinear rheological\nproperties of entangled ring-linear DNA blends and their composites with rigid\nmicrotubules. We show that the linear viscoelasticity is primarily dictated by\nthe microtubules at lower frequencies, but their contributions become frozen\nout at frequencies above the DNA entanglement rate. In the nonlinear regime, we\nreveal that mechanical response features, such as shear thinning, stress\nsoftening and multi-modal relaxation dynamics are mediated by entropic\nstretching, threading, and flow alignment of entangled DNA, as well as forced\nde-threading, disentanglement, and clustering. The contributions of each of\nthese mechanisms depend on the strain rate as well as the entanglement density\nand stiffness of the polymers, leading to non-monotonic rate dependences of\nmechanical properties that are most pronounced for highly concentrated\nring-linear blends rather than DNA-MT composites."
    },
    {
        "anchor": "Structure and Depletion at Fluoro- and Hydro-carbon/Water Liquid/Liquid\n  Interfaces: The results of x-ray reflectivity studies of two oil/water (liquid/liquid)\ninterfaces are inconsistent with recent predictions of the presence of a\nvapor-like depletion region at hydrophobic/aqueous interfaces. One of the oils,\nperfluorohexane, is a fluorocarbon whose super-hydrophobic interface with water\nprovides a stringent test for the presence of a depletion layer. The other oil,\nheptane, is a hydrocarbon and, therefore, is more relevant to the study of\nbiomolecular hydrophobicity. These results are consistent with the sub-angstrom\nproximity of water to soft hydrophobic materials.",
        "positive": "Effect of chain stiffness on the dynamics and microstructure of\n  crystallizable bead-spring polymer melts: We constrast the dynamics in model unentangled polymer melts of chains of\nthree different stiffnesses: flexible, intermediate, and rodlike. Flexible and\nrodlike chains, which readily solidify into close-packed crystals (respectively\nwith randomly oriented and nematically aligned chains), display simple melt\ndynamics with Arrhenius temperature dependence and a discontinuous change upon\nsolidification. Intermediate-stiffness chains, however, are fragile\nglass-formers displaying Vogel-Fulcher dynamical arrest, despite the fact that\nthey also possess a nematic-close-packed crystalline ground state. To connect\nthis difference in dynamics to the differing microstructure of the melts, we\nexamine how various measures of structure, including cluster-level metrics\nrecently introduced in studies of colloidal systems, vary with chain stiffness\nand temperature. No clear static-structural cause of the dynamical arrest is\nfound. However, we find that the intermediate-stiffness chains display\nqualitatively different dynamical heterogeneity. Specifically, their stringlike\ncorrelated motion (cooperative rearrangement) is correlated along chain\nbackbones in a way not found for either flexible or rodlike chains. This\nactivated \"crawling\" motion seems to be the cause of the dynamical arrest\nobserved for these systems, and shows that the factors controlling the\ncrystallization vs.\\ glass formation competition in polymers likely depend\nnonmonotonically on chain stiffness."
    },
    {
        "anchor": "Direct Determination of DNA Twist-Stretch Coupling: The symmetries of the DNA double helix require a new term in its linear\nresponse to stress: the coupling between twist and stretch. Recent experiments\nwith torsionally-constrained single molecules give the first direct measurement\nof this important material parameter. We extract its value from a recent\nexperiment of Strick et al. [Science 271 (1996) 1835] and find rough agreement\nwith an independent experimental estimate recently given by Marko. We also\npresent a very simple microscopic theory predicting a value comparable to the\none observed.",
        "positive": "Nanoparticle characterization by continuous contrast variation in SAXS\n  with a solvent density gradient: Many low-density nanoparticles show a radial inner structure. This work\nproposes a novel approach to contrast variation with SAXS based on the\nconstitution of a solvent density gradient in a glass capillary in order to\nresolve this internal morphology. Scattering curves of a polymeric core-shell\ncolloid were recorded at different suspending medium contrasts at the\nfour-crystal monochromator beamline of PTB at the synchrotron radiation\nfacility BESSY II. The mean size and size distribution of the particles as well\nas an insight into the colloid electron density composition were determined\nusing the position of the isoscattering points in the Fourier region of the\nscattering curves and by examining the Guinier region in detail. These results\nwere corroborated with a model fit to the experimental data, which provided\ncomplementary information about the inner electron density distribution of the\nsuspended nanoparticles."
    },
    {
        "anchor": "Configurational Entropy and Diffusivity of Supercooled Water: We calculate the configurational entropy S_conf for the SPC/E model of water\nfor state points covering a large region of the (T,rho) plane. We find that (i)\nthe (T,rho) dependence of S_conf correlates with the diffusion constant and\n(ii) that the line of maxima in S_conf tracks the line of density maxima. Our\nsimulation data indicate that the dynamics are strongly influenced by S_conf\neven above the mode-coupling temperature T_MCT(rho).",
        "positive": "Planar sheets meet negative curvature liquid interfaces: If an inextensible thin sheet is adhered to a substrate with a negative\nGaussian curvature it will experience stress due to geometric frustration. We\nanalyze the consequences of such geometric frustration using analytic arguments\nand numerical simulations. Both concentric wrinkles and eye-like folds are\nshown to be compatible with negative curvatures. Which pattern will be realized\ndepends on the curvature of the substrate. We discuss both types of folding\npatterns and determine the phase diagram governing their appearance."
    },
    {
        "anchor": "An $[\u03b7]$ Linear in $M$ Does Not Imply Rouse Dynamics: Contrary to some expectations, an experimental finding for a polymer that the\nsolution intrinsic viscosity $[\\eta]$ or the melt viscosity is linear in the\npolymer molecular weight $M$ does not indicate that polymer dynamics are\nRouselike. Why? The other major polymer dynamic model, due to Kirkwood and\nRiseman [\\emph{J. Chem.\\ Phys.\\ } \\textbf{16}, 565-573 (1948)], leads in its\nfree-draining form to a prediction $[\\eta] \\sim M$, even though the polymer\nmotions in this model are totally unlike the polymer motions in the Rouse\nmodel. In the Rouse model, the chain motions are linear translation and\ninternal ('Rouse') modes. In the Kirkwood-Riseman model (and its free-draining\nform, derived here), the chain motions are translation and whole-body rotation.\nThe difference arises because Rouse's calculation implicitly refers only to\nchains subject to zero external shear force (And, as an aside, Rouse's\nconstruction of $[\\eta]$ is invalid, because it concludes that there is viscous\ndissipation in a system that Rouse implicitly assumed to have no applied\nshear).",
        "positive": "Melting of Colloidal Molecular Crystals on Triangular Lattices: The phase behavior of a two-dimensional colloidal system subject to a\ncommensurate triangular potential is investigated. We consider the integer\nnumber of colloids in each potential minimum as rigid composite objects with\neffective discrete degrees of freedom. It is shown that there is a rich variety\nof phases including ``herring bone'' and ``Japanese 6 in 1'' phases. The\nensuing phase diagram and phase transitions are analyzed analytically within\nvariational mean-field theory and supplemented by Monte Carlo simulations.\nConsequences for experiments are discussed."
    },
    {
        "anchor": "Kinetic Partitioning Mechanism as a Unifying Theme in the Folding of\n  Biomolecules: We present a unified framework for folding kinetics of proteins and RNA. The\nbasis for this framework relies on the notion of topological frustration, which\ngives rise to several competing basins of attraction (CBA) in addition to the\nnative basin of attraction (NBA) on the free energy surface. A rough free\nenergy surface results in direct and indirect pathways to the NBA, i.e., a\nkinetic partitioning mechanism (KPM). The unified framework for folding\nkinetics allows us to propose a foldability principle, according to which fast\nfolding sequences are characterized by the folding transition temperature\n$T_{F}$ being close to the collapse transition temperature $T_{\\theta }$.\nBiomolecules, for which foldability principle is satisfied, such as small\nproteins and tRNAs, are expected to fold rapidly with two-state kinetics.\nEstimates for the multiple time scales in KPM are also given.",
        "positive": "Charged dendrimers revisited: Effective charge and surface potential of\n  dendritic polyglycerol sulfate: We investigate key electrostatic features of charged dendrimers at hand of\nthe biomedically important dendritic polyglycerol sulfate (dPGS) macromolecule\nusing multi-scale computer simulations and Zetasizer experiments. In our\nsimulation study, we first develop an effective mesoscale Hamiltonian specific\nto dPGS based on input from all-atom, explicit-water simulations of dPGS of low\ngeneration. Employing this in coarse-grained, implicit-solvent/explicit-salt\nLangevin dynamics simulations, we then study dPGS structural and electrostatic\nproperties up to the sixth generation. By systematically mapping then the\ncalculated electrostatic potential onto the Debye-H\\\"uckel form -- that serves\nas a basic defining equation for the effective charge -- we determine\nwell-defined effective net charges and corresponding radii, surface charge\ndensities, and surface potentials of dPGS. The latter are found to be up to one\norder of magnitude smaller than the bare values and consistent with previously\nderived theories on charge renormalization and weak saturation for high\ndendrimer generations (charges). Finally, we find that the surface potential of\nthe dendrimers estimated from the simulations compare very well with our new\nelectrophoretic experiments."
    },
    {
        "anchor": "Segment-Scale, Force-Level Theory of Mesoscopic Dynamic Localization and\n  Entropic Elasticity in Entangled Chain Polymer Liquids: We develop a segment-scale, force-based theory for the breakdown of the\nunentangled Rouse model and subsequent emergence of isotropic mesoscopic\nlocalization and entropic elasticity in chain polymer liquids in the absence of\nergodicity-restoring anisotropic reptation motion. The theory is formulated in\nterms of a conformational N-dynamic-order-parameter Generalized Langevin\nEquation approach. It is implemented using a field-theoretic Gaussian thread\nmodel of polymer structure and closed in a universal manner at the level of the\nchain dynamic second moment matrix. The physical idea is that the isotropic\nRouse model fails due to the dynamical emergence of time-persistent\nintermolecular contacts determined by the combined influence of local chain\nuncrossability, long range polymer connectivity and a self-consistent treatment\nof chain motion and the dynamic forces that hinder it. For long chain melts,\nthe mesoscopic localization length (tube diameter) and emergent elasticity\npredictions are in near quantitative agreement with experiment. Moreover, the\nonset chain length scales with the semi-dilute crossover concentration with a\nrealistic numerical prefactor. Distinctive predictions are made for various\noff-diagonal correlation functions that quantify the full spatial structure of\nthe dynamically localized polymer conformation. As the local uncrossability\nconstraint and/or intrachain bonding spring are softened, the tube diameter is\npredicted to swell until it reaches the chain radius-of-gyration at which point\nentanglement localization vanishes in a discontinuous manner. A full dynamic\nphase diagram for the destruction of mesoscopic localization is constructed,\nwhich is qualitatively consistent with simulations and the classical concept of\nan entanglement degree of polymerization.",
        "positive": "Anomalous Structure and Scaling of Ring Polymer Brushes: A comparative simulation study of polymer brushes formed by grafting at a\nplanar surface either flexible linear polymers (chain length $N_L$) or\n(non-catenated) ring polymers (chain length $N_R=2 N_L$) is presented. Two\ndistinct off-lattice models are studied, one by Monte Carlo methods, the other\nby Molecular Dynamics, using a fast implementation on graphics processing units\n(GPUs). It is shown that the monomer density profiles $\\rho(z)$ in the\n$z$-direction perpendicular to the surface for rings and linear chains are\npractically identical, $\\rho_R(2 N_L, z)=\\rho_L(N_L, z)$. The same applies to\nthe pressure, exerted on a piston at hight z, as well. While the gyration radii\ncomponents of rings and chains in $z$-direction coincide, too, and increase\nlinearly with $N_L$, the transverse components differ, even with respect to\ntheir scaling properties: $R_{gxy}^{(L)} \\propto N_L^{1/2}$, $R_{gxy}^{(R)}\n\\propto N_L^{0.4}$. These properties are interpreted in terms of the\nstatistical properties known for ring polymers in dense melts."
    },
    {
        "anchor": "Four-Wave Mixing In BEC Systems With Multiple Spin States: We calculate the four-wave mixing (FWM) in a Bose-Einstein condensate system\nhaving multiple spin wave packets that are initially overlapping in physical\nspace, but have nonvanishing relative momentum that cause them to recede from\none another. Three receding condensate atom wave packets can result in\nproduction of a fourth wave packet by the process of FWM due to atom-atom\ninteractions. We consider cases where the four final wave packets are composed\nof 1, 2, 3 and 4 different internal spin components. FWM with 1- or 2-spin\nstate wave packets is much stronger than 3- or 4-spin state FWM, wherein two of\nthe coherent moving BEC wave packets form a polarization-grating that rotates\nthe spin projection of the third wave into that of fourth diffracted wave (as\nopposed to the 1- or 2-spin state case where a regular density-grating is\nresponsible for the diffraction). Calculations of FWM for $^{87}$Rb and\n$^{23}$Na condensate systems are presented.",
        "positive": "Deformability-based red blood cell separation in deterministic lateral\n  displacement devices - a simulation study: We show, via three-dimensional\nimmersed-boundary-finite-element-lattice-Boltzmann simulations, that\ndeformability-based red blood cell (RBC) separation in deterministic lateral\ndisplacement (DLD) devices is possible. This is due to the\ndeformability-dependent lateral extension of RBCs and enables us to predict a\npriori which RBCs will be displaced in a given DLD geometry. Several diseases\naffect the deformability of human cells. Malaria-infected RBCs or sickle cells,\nfor example, tend to become stiffer than their healthy counterparts. It is\ntherefore desirable to design microfluidic devices which can detect those\ndiseases based on the cells' deformability fingerprint, rather than preparing\nsamples using expensive and time-consuming biochemical preparation steps. Our\nfindings should be helpful in the development of new methods for sorting cells\nand particles by deformability."
    },
    {
        "anchor": "Mechanical surface tension governs membrane thermal fluctuations: Motivated by the still ongoing debate about the various possible meanings of\nthe term surface tension of bilayer membranes, we present here a detailed\ndiscussion that explains the differences between the \"intrinsic\",\n\"renormalized\", and \"mechanical\" tensions. We use analytical considerations and\ncomputer simulations to show that the membrane spectrum of thermal fluctuations\nis governed by the mechanical and not the intrinsic tension. Our study\nhighlights the fact that the commonly used quadratic approximation of Helfrich\neffective Hamiltonian is not rotationally invariant. We demonstrate that this\nnon-physical feature leads to a calculated mechanical tension that differs\ndramatically from the correct mechanical tension. Specifically, our results\nsuggest that the mechanical and intrinsic tensions vanish simultaneously, which\ncontradicts recent theoretical predictions derived for the approximated\nHamiltonian.",
        "positive": "Interfacial Velocity Corrections due to Multiplicative Noise: The problem of velocity selection for reaction fronts has been intensively\ninvestigated, leading to the successful marginal stability approach for\npropagation into an unstable state. Because the front velocity is controlled by\nthe leading edge which perforce has low density, it is interesting to study the\nrole that finite particle number fluctuations have on this picture. Here, we\nuse the well-known mapping of discrete Markov processes to stochastic\ndifferential equations and focus on the front velocity in the simple $A+A\n\\stackrel{\\leftarrow}{\\to} A$ system. Our results are consistent with a recent\n(heuristic) proposal that $v_{MS} - v \\sim {1\\over \\ln^2 {N}}$."
    },
    {
        "anchor": "Acceleration and suppression of banana-shaped-protein-induced tubulation\n  by addition of small membrane inclusions of isotropic spontaneous curvatures: The membrane tubulation induced by banana-shaped protein rods is investigated\nby using coarse-grained meshless membrane simulations. It is found that the\ntubulation is promoted by laterally isotropic membrane inclusions that generate\nthe same sign of spontaneous curvature as the adsorbed protein rods. The\ninclusions are concentrated in the tubules and reduce the bending energy of the\ntip of the tubules. On the other hand, the inclusions with an opposite\ncurvature suppress the tubulation by percolated-network formation at a high\nprotein-rod density while they induce a spherical membrane bud at a low rod\ndensity. When equal amounts of the two types of inclusions (with positive and\nnegative curvatures) are added, their effects cancel each other for the first\nshort period but later the tubulation is slowly accelerated. A positive surface\ntension suppresses the tubulation. Out results suggest that the cooperation of\nscaffolding of BAR (Bin/Amphiphysin/Rvs) domains and isotropic membrane\ninclusions is important for the tubulation.",
        "positive": "Pitcher Plant Inspired Biomimetic Liquid Infused Slippery Surface Using\n  Taro Leaf: Bio-inspired anti-wetting surfaces, such as lotus leaf or pitcher plant, have\nled to the development of stable liquid infused slippery surfaces for various\nscientific applications. The present work demonstrates the use of biomimetic\nsuperhydrophobic surface (inspired from taro leaf) for fabrication of a stable\nair-liquid film. The taro leaf replica is fabricated on PDMS using two step\nsoft-molding technique, where microstructures of the replicated surface are\nused to retain silicone oil layer to form a stable slippery surface. The\nfabricated surface exhibits a low contact angle hysteresis (CAH) of 2{\\deg},\nwith sliding angle (SA) of 1.1{\\deg}, which further affirms the super-slippery\nnature of the surface. Furthermore, it also shows excellent self-repairing\nability, thermal stability and long-term durability of the oil coating against\nhigh shear rates, high impact droplets etc. We thus envisage that the present\nmethod of fabrication of slippery surface is simple and economical, and thus\nuseful for various applications such as water drag reduction, self-cleaning,\nanti-fogging, anti-fouling etc."
    },
    {
        "anchor": "Co-non-solvency: Mean-field polymer theory does not describe polymer\n  collapse transition in a mixture of two competing good solvents: Smart polymers are a modern class of polymeric materials that often exhibit\nunpredictable behavior in mixtures of solvents. One such phenomenon is\nco-non-solvency. Co-non-solvency occurs when two (perfectly) miscible and\ncompeting good solvents, for a given polymer, are mixed together. As a result,\nthe same polymer collapses into a compact globule within intermediate mixing\nratios. More interestingly, polymer collapses when the solvent quality remains\ngood and even gets increasingly better by the addition of the better cosolvent.\nThis is a puzzling phenomenon that is driven by strong local concentration\nfluctuations. Because of the discrete particle based nature of the\ninteractions, Flory-Huggins type mean field arguments become unsuitable. In\nthis work, we extend the analysis of the co-non-solvency effect presented\nearlier [Nature Communications 5, 4882 (2014)]. We explain why co-non-solvency\nis a generic phenomenon that can be understood by the thermodynamic treatment\nof the competitive displacement of (co)solvent components. This competition can\nresult in a polymer collapse upon improvement of the solvent quality. Specific\nchemical details are not required to understand these complex conformational\ntransitions. Therefore, a broad range of polymers are expected to exhibit\nsimilar reentrant coil-globule-coil transitions in competing good solvents.",
        "positive": "On two continuous models for the dynamics of sandpile surfaces: We consider a modified BCRE model for pile surface dynamics (Bouchaud, Cates,\nRavi Prakash, and Edwards, J. Phys. I France, v. 4, p. 1383, 1994) and show\nthat in the long-scale limit this model converges to a quasistationary model of\npile growth in the form of an evolutionary variational inequality (Prigozhin,\nPhys. Rev. E, v. 49, p. 1161, 1994)."
    },
    {
        "anchor": "Barrier crossing in a viscoelastic bath: We investigate the hopping dynamics of a colloidal particle across a\npotential barrier and within a viscoelastic, i.e., non-Markovian bath, and\nreport two clearly separated time scales in the corresponding waiting time\ndistributions. While the longer time scale exponentially depends on the barrier\nheight, the shorter one is similar to the relaxation time of the fluid. This\nshort time scale is a signature of the storage and release of elastic energy\ninside the bath, that strongly increases the hopping rate. Our results are in\nexcellent agreement with numerical simulations of a simple Maxwell model.",
        "positive": "Statistical Theory of Force Induced Unzipping of DNA: The unzipping transition under the influence of external force of a dsDNA\nmolecule has been studied using the Peyrard-Bishop Hamiltonian. The critical\nforce $F_c(T)$ is found to depend on the potential parameters $k$, represents\nthe stiffness of single strand of DNA and the potential depth $D$. We used\nconstant extension ensemble to calculate the average force needed to stretch a\nbase pair $y$ distance apart. A very large peak around $y = 1 {\\rm \\AA}$ is\nfound. The value of $F(y)$ needed to stretch a base pair located far away from\nthe ends of a dsDNA molecule is found twice the value of the force needed to\nstretch a base pair located at one of the ends to the same distance. The effect\nof mismatching in the base pairs on the peak height and position is\ninvestigated. The formation and behaviour of a loop of Y shape when one of the\nends base pair is stretched and a bubble of ssDNA with the shape of \"an eye\"\nwhen a base pair far from ends is stretched are investigated."
    },
    {
        "anchor": "Indentation of an elastic arch on a frictional substrate: Pinning,\n  unfolding and snapping: We investigate the morphology and mechanics of a naturally curved elastic\narch loaded at its center and frictionally supported at both ends on a flat,\nrigid substrate. Through systematic numerical simulations, we classify the\nobserved behaviors of the arch into three distinct types of configurations in\nterms of the arch geometry and the coefficient of static friction with the\nsubstrate. A linear theory is developed based on a planar elastica model\ncombined with Amontons-Coulomb's frictional law, which quantitatively explains\nthe numerically constructed phase diagram. The snapping transition of a loaded\narch in a sufficiently large indentation regime, which involves a discontinuous\nforce jump, is numerically observed. The proposed model problem allows a fully\nanalytical investigation and demonstrates a rich variety of mechanical\nbehaviors owing to the interplay between elasticity, geometry, and friction.\nThis study provides a basis for understanding more common but complex systems,\nsuch as a cylindrical shell subjected to a concentrated load and simultaneously\nsupported by frictional contact with surrounding objects.",
        "positive": "Layer-by-layer assembly of colloidal particles deposited onto the\n  polymer-grafted elastic substrate: We demonstrate a novel route of spatially organizing the colloid arrangements\non the polymer-grafted substrate by use of self-consistent field and density\nfunctional theories. We find that grafting of polymers onto a substrate can\neffectively control spatial dispersions of deposited colloids as a result of\nthe balance between colloidal settling force and entropically elastic force of\nbrushes, and colloids can form unexpected ordered structures on a grafting\nsubstrate. The depositing process of colloidal particles onto the elastic\n\"soft\" substrate includes two steps: brush-mediated one-dimensional arrangement\nof colloidal crystals and controlled layer-by-layer growth driven entropically\nby non-adsorbing polymer solvent with increasing the particles. The result\nindicates a possibility for the production of highly ordered and defect-free\nstructures by simply using the grafted substrate instead of periodically\npatterned templates, under appropriate selection of colloidal size, effective\ndepositing potential, and brush coverage density."
    },
    {
        "anchor": "Lattice Boltzmann simulations of a viscoelastic shear-thinning fluid: We present a hybrid lattice Boltzmann algorithm for the simulation of flow\nglass-forming fluids, characterized by slow structural relaxation, at the level\nof the Navier-Stokes equation. The fluid is described in terms of a nonlinear\nintegral constitutive equation, relating the stress tensor locally to the\nhistory of flow. As an application, we present results for an integral\nnonlinear Maxwell model that combines the effects of (linear) viscoelasticity\nand (nonlinear) shear thinning. We discuss the transient dynamics of\nvelocities, shear stresses, and normal stress differences in planar\npressure-driven channel flow, after switching on (startup) and off (cessation)\nof the driving pressure. This transient dynamics depends nontrivially on the\nchannel width due to an interplay between hydrodynamic momentum diffusion and\nslow structural relaxation.",
        "positive": "A Microscopic Description of the Granular Fluidity Field in Nonlocal\n  Flow Modeling: A recent granular rheology based on an implicit `granular fluidity' field has\nbeen shown to quantitatively predict many nonlocal phenomena. However, the\nphysical nature of the field has not been identified. Here, the granular\nfluidity is found to be a kinematic variable given by the velocity fluctuation\nand packing fraction. This is verified with many discrete element simulations,\nwhich show the operational fluidity definition, solutions of the fluidity\nmodel, and the proposed microscopic formula all agree. Kinetic theoretical and\nEyring-like explanations shed insight into the obtained form."
    },
    {
        "anchor": "How does torsional rigidity affect the wrapping transition of a\n  semiflexible chain around a spherical core?: We investigated the effect of torsional rigidity of a semiflexible chain on\nthe wrapping transition around a spherical core, as a model of nucleosome, the\nfundamental unit of chromatin. Through molecular dynamics simulation, we show\nthat the torsional effect has a crucial effect on the chain wrapping around the\ncore under the topological constraints. In particular, the torsional stress (i)\ninduces the wrapping/unwrapping transition, and (ii) leads to a unique complex\nstructure with an antagonistic wrapping direction which never appears without\nthe topological constraints. We further examine the effect of the stretching\nstress for the nucleosome model, in relation to the unique characteristic\neffect of the torsional stress on the manner of wrapping.",
        "positive": "Dynamic mechanical analysis of supercooled water in nanoporous\n  confinement: Dynamical mechanical analysis (DMA)(f=0.2 - 100 Hz) is used to study the\ndynamics of confined water in mesoporous Gelsil (2.6 nm and 5 nm pores) and\nVycor (10 nm) in the temperature range from T=80 K to 300 K. Confining water\ninto nanopores partly suppresses crystallization and allows us to perform\nmeasurements of supercooled water below 235 K, i.e. in water's so called \"no\nman's land\", in parts of the pores. Two distinct relaxation peaks are observed\naround T1 = 145 K (P1) and T2 = 205 K (P2) for Gelsil 2.6 nm and Gelsil 5 nm at\n0.2 Hz. Both peaks shift to higher T with increasing pore size d and change\nwith f in a systematic way, typical of an Arrhenius behaviour of the\ncorresponding relaxation times. For P1 we obtain an average activation energy\nof Ea=0.47 eV, in good agreement with literature values. It is suggested that\nP1 corresponds to the glass transition of supercooled water far from pore\nwalls, whereas P2 reflects the dynamics of water molecules near the surface of\nthe pores. The observation of a pronounced softening of the Young's modulus\naround 165 K (for Gelsil 2.6 nm at 0.2 Hz) is in agreement with a\nglass-to-liquid transition in the vicinity of P1. In addition we find a\nclear-cut 1=d-dependence of the calculated glass transition temperatures which\nextrapolates to Tg(1/d=0)=136 K, i.e. the traditional value of water."
    },
    {
        "anchor": "Models for membrane curvature sensing of curvature generating proteins: The curvature sensitive localization of proteins on membranes is vital for\nmany cell biological processes. Coarse-grained models are routinely employed to\nstudy the curvature sensing phenomena and membrane morphology at the length\nscale of few micrometers. Two prevalent phenomenological models exist for\nmodeling experimental observations of curvature sensing, (1) the spontaneous\ncurvature model and (2) the curvature mismatch model, which differ in their\ntreatment of the change in elastic energy due to the binding of proteins on the\nmembrane. In this work, the prediction of sensing and generation behaviour, by\nthese two models, are investigated using analytical calculations as well as\nDynamic Triangulation Monte Carlo simulations of quasi-spherical vesicles.\nWhile the spontaneous curvature model yields a monotonically decreasing sensing\ncurve as a function of vesicle radius, the curvature mismatch model results in\na non-monotonic sensing curve. We highlight the main differences in the\ninterpretation of the protein-related parameters in the two models. We further\npropose that the spontaneous curvature model is appropriate for modeling\nperipheral proteins employing the hydrophobic insertion mechanism, with minimal\nmodification of membrane rigidity, while the curvature mismatch model is\nappropriate for modeling curvature generation using scaffolding mechanism where\nthere is significant stiffening of the membrane due to protein binding.",
        "positive": "Anisotropic electrostatic screening of charged colloids in nematic\n  solvents: The physical behaviour of anisotropic charged colloids is determined by their\nmaterial dielectric anisotropy, affecting colloidal self-assembly, biological\nfunction and even out-of-equilibrium behaviour. However, little is known about\nanisotropic electrostatic screening, which underlies all electrostatic\neffective interactions in such soft or biological materials. In this work, we\ndemonstrate anisotropic electrostatic screening for charged colloidal particles\nin a nematic electrolyte. We show that material anisotropy behaves markedly\ndifferent from particle anisotropy: The electrostatic potential and pair\ninteractions decay with an anisotropic Debye screening length, contrasting the\nconstant screening length for isotropic electrolytes. Charged dumpling-shaped\nnear-spherical colloidal particles in a nematic medium are used as an\nexperimental model system to explore the effects of anisotropic screening,\ndemonstrating competing anisotropic elastic and electrostatic effective pair\ninteractions for colloidal surface charges tunable from neutral to high,\nyielding particle-separated metastable states. Generally, our work contributes\nto the understanding of electrostatic screening in nematic anisotropic media."
    },
    {
        "anchor": "Area per Lipid in DPPC-Cholesterol Bilayers:Analytical Approach: Area per molecule in a DPPC-Cholesterol bilayers depends non-linearly on the\ncholesterol concentration. Using flexible strings model of lipid membranes we\ncalculate area per molecule in DPPC-Cholesterol mixtures in the biologically\nrelevant concentrations range. Few parameters of the model are optimized for a\nperfect agreement with the area per lipid data available from molecular\ndynamics simulations. Lateral pressure at the hydrophilic interface, {\\gamma},\nis taken to be proportional to the cholesterol concentration. Non-linearity\narises as a consequence of the non-linear dependence of thermodynamical\nequilibrium area of molecules on {\\gamma}. DPPC lipid is modeled as flexible\nstring of finite thickness and a given bending rigidity, while cholesterol\nmolecule is modeled as rigid rod with finite thickness and infinite rigidity.\nUsing parameters fitted to reproduce area per molecule dependence on\ncholesterol concentration, we had further calculated our model predictions for\nthe NMR order parameter of DPPC lipid chains and coefficient of thermal area\nexpansion. The microscopic nature of the model allows to consider a broad range\nof thermodynamic phenomena.",
        "positive": "Pattern orientation in finite domains without boundaries: We investigate the orientation of nonlinear stripe patterns in finite\ndomains. Motivated by recent experiments, we introduce a control parameter drop\nfrom supercritical inside a domain to subcritical outside without boundary\nconditions at the domain border. As a result, stripes align perpendicular to\nshallow control parameter drops. For steeper drops, non-adiabatic effects lead\nto a surprising orientational transition to parallel stripes with respect to\nthe borders. We demonstrate this effect in terms of the Brusselator model and\ngeneric amplitude equations."
    },
    {
        "anchor": "Chemotactic self-caging in active emulsions: A common feature of biological self-organization is how active agents\ncommunicate with each other or their environment via chemical signaling. Such\ncommunications, mediated by self-generated chemical gradients, have\nconsequences for both individual motility strategies and collective migration\npatterns. Here, in a purely physicochemical system, we use self-propelling\ndroplets as a model for chemically active particles that modify their\nenvironment by leaving chemical footprints, which act as chemorepulsive signals\nto other droplets. We analyze this communication mechanism quantitatively both\non the scale of individual agent-trail collisions as well as on the collective\nscale where droplets actively remodel their environment while adapting their\ndynamics to that evolving chemical landscape. We show in experiment and\nsimulation how these interactions cause a transient dynamical arrest in active\nemulsions where swimmers are caged between each other's trails of secreted\nchemicals. Our findings provide new insight into the collective dynamics of\nchemically active particles and yield principles for predicting how negative\nautochemotaxis shapes their navigation strategy.",
        "positive": "Ferrihydrite nanoparticles entrapped in shear-induced multilamellar\n  vesicles: Hypothesis Ferrihydrite (Fh) nanoparticles are receiving considerable\nscientific interest due to their large reactive surface areas, crystalline\nstructures, and nanoparticle morphology. They are of great importance in\nbiogeochemical processes and have the ability to sequester hazardous and toxic\nsubstances. Here, the working hypothesis was to entrap fractal-like Fh\nnanoparticles, with a radius of gyration of 6.2 nm and a primary building block\nof polydisperse spheres with a radius of 0.8 nm, in a shear-induced\nmultilamellar vesicle (MLV) state using a 40 wt.% polyethylene glycol dodecyl\nether surfactant. Experiments Small- and Wide- Angle X-ray scattering revealed\nthe equilibrium state of the non-ionic planar lamellar phase, the Fh\ndispersion, and their mixture. The MLV state was induced by using a shear flow\nin a Taylor-Couette geometry of a rheometer. Findings The nonionic surfactant\ninitially exhibited a lamellar gel phase with two distinct d-spacings of 11.0\nand 9.7 nm, which collapsed into the MLV state under shear flow. The Fh\nnanoparticles induced bilayer attraction by suppressing lamellar layer\nundulations, decreasing the d-spacing. These results are helpful in the\nunderstanding of the relationship between nanoparticle size and\nnanoparticle-bilayers interactions and provides insight on Fh encapsulations in\na kinetically stable MLVs state."
    },
    {
        "anchor": "Test of the Stokes-Einstein relation in a two-dimensional Yukawa liquid: The Stokes-Einstein relation, relating the diffusion and viscosity\ncoefficients D and eta, is tested in two dimensions. An equilibrium\nmolecular-dynamics simulation was used with a Yukawa pair potential. Regimes\nare identified where motion is diffusive and D is meaningful. The\nStokes-Einstein relation, D ~ kT, was found to be violated near the disordering\ntransition; under these conditions collective particle motion exhibits\ndynamical heterogeneity. At slightly higher temperatures, however, the\nStokes-Einstein relation is valid. These results may be testable in\nstrongly-coupled dusty plasma experiments.",
        "positive": "2H-NMR studies of supercooled and glassy aspirin: Acetyl salicylic acid, deuterated at the methyl group, was investigated using\n2H-NMR in its supercooled and glassy states. Just above the glass transition\ntemperature the molecular reorientations were studied using stimulated-echo\nspectroscopy and demonstrated a large degree of similarity with other glass\nformers. Deep in the glassy phase the NMR spectra look similar to those\nreported for the crystal [A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z.\nOlejniczak, Z. T. Lalowicz, Z. Naturforsch. A 50 (1995) 95] and below 20 K they\nare indicative for rotational tunneling with a relatively large tunneling\nfrequency. Measurements of the spin-lattice relaxation times for temperatures\nbelow 150 K reveal a broad distribution of correlation times in the glass. The\ndominant energy barrier characterizing the slow-down of the methyl group is\nsignificantly smaller than the well defined barrier in the crystal."
    },
    {
        "anchor": "Renormalized one-loop theory of correlations in polymer blends: The renormalized one-loop theory is a coarse-grained theory of corrections to\nthe self-consistent field theory (SCFT) of polymer liquids, and to the random\nphase approximation (RPA) theory of composition fluctuations. We present\npredictions of corrections to the RPA for the structure function $S(k)$ and to\nthe random walk model of single-chain statics in binary homopolymer blends. We\nconsider an apparent interaction parameter $\\chi_{a}$ that is defined by\napplying the RPA to the small $k$ limit of $S(k)$. The predicted deviation of\n$\\chi_{a}$ from its long chain limit is proportional to $N^{-1/2}$, where $N$\nis chain length. This deviation is positive (i.e., destabilizing) for weakly\nnon-ideal mixtures, with $\\chi_{a} N \\alt 1$, but negative (stabilizing) near\nthe critical point. The positive correction to $\\chi_{a}$ for low values of\n$\\chi_{a} N$ is a result of the fact that monomers in mixtures of shorter\nchains are slightly less strongly shielded from intermolecular contacts. The\ndepression in $\\chi_{a}$ near the critical point is a result of long-wavelength\ncomposition fluctuations. The one-loop theory predicts a shift in the critical\ntemperature of ${\\cal O}(N^{-1/2})$, which is much greater than the predicted\n${\\cal O}(N^{-1})$ width of the Ginzburg region. Chain dimensions deviate\nslightly from those of a random walk even in a one-component melt, and contract\nslightly with increasing $\\chi_{e}$. Predictions for $S(k)$ and single-chain\nproperties are compared to published lattice Monte Carlo simulations.",
        "positive": "The concept of entropic rectifier facing experiments: The transport of molecules in confined media is subject to entropic barriers.\nSo theoretically, asymmetry of the confinement length may lead to molecular\nratchets with entropy as the only driving force for the biased transport. We\naddress experimentally this question by performing alternative ionic current\nmeasurements on electrolytes confined in neutral conical nanopores. In case\nanions and cations widely differ in size, we show that rectification of ionic\ncurrent can be obtained that depends on ions size and cycle frequency,\nconsistently with the entropic ratchet mechanism."
    },
    {
        "anchor": "Nature's forms are frilly, flexible, and functional: A ubiquitous motif in nature is the self-similar hierarchical buckling of a\nthin lamina near its margins. This is seen in leaves, flowers, fungi, corals,\nand marine invertebrates. We investigate this morphology from the perspective\nof non-Euclidean plate theory. We identify a novel type of defect, a\nbranch-point of the normal map, that allows for the generation of such complex\nwrinkling patterns in thin elastic hyperbolic surfaces, even in the absence of\nstretching. We argue that branch points are the natural defects in hyperbolic\nsheets, they carry a topological charge which gives them a degree of\nrobustness, and they can influence the overall morphology of a hyperbolic\nsurface without concentrating elastic energy. We develop a theory for branch\npoints and investigate their role in determining the mechanical response of\nhyperbolic sheets to weak external forces.",
        "positive": "Bubble formation due to capillary instability during evaporation of a\n  porous medium: We show that during evaporation of a pore network, liquid can refill the gas\noccupied pores, snapping off a gas bubble, which then moves to a stable\nconfiguration. This phenomenon is induced by the capillary instability due to\nthe wettability heterogeneity of the pore network and has a much smaller time\nscale as compared to the evaporation process. The capillary instability induced\nliquid refilling and bubble movement are explained in detail based on the\nanalysis of the images obtained from the visualization experiment. The\ncapillary valve effect, which hinders the movement of the gas-liquid interface\nand is induced by the sudden geometrical expansion between small and large\npores, can be suppressed by the residual liquid in the large pore. For better\nunderstanding of the capillary instability induced gas-liquid two-phase\ntransport during evaporation, a novel pore network model is developed, which\nconsiders not only the capillary and viscous forces but also the inertial\nforces that are seldom taken into account in the previous models. The pore\nnetwork modeling results are in good agreement with the experimental data,\ndemonstrating the effectiveness of the developed pore network model, which\nopens up a new route for better understanding of the role of inertial forces in\ntwo-phase transport in porous media."
    },
    {
        "anchor": "Phase separation and folding in swelled nematoelastic films: We explore reshaping of nematoelastic films upon imbibing an isotropic\nsolvent under conditions when isotropic and nematic phases coexist. The\nstructure of the interphase boundary is computed taken into account the optimal\nnematic orientation governed by interaction of gradients of the nematic order\nparameter and solvent concentration. This structure determines the effective\nline tension of the boundary. We further compute equilibrium shapes of deformed\nthin sheets and cylindrical and spherical shells with the rectilinear or\ncircular shape of the boundary between nematic and isotropic domains. A\ndifferential expansion or contraction near this boundary generates a folding\npattern spreading out into the bulk of both phases. The hierarchical ordering\nof this pattern is most pronounced on a cylindrical shell.",
        "positive": "Designing the pressure-dependent shear modulus using tessellated\n  granular metamaterials: Jammed packings of granular materials display complex mechanical response.\nFor example, the ensemble-averaged shear modulus $\\left\\langle G \\right\\rangle$\nincreases as a power-law in pressure $p$ for static packings of soft spherical\nparticles that can rearrange during compression. We seek to design granular\nmaterials with shear moduli that can either increase {\\it or} decrease with\npressure without particle rearrangements even in the large-system limit. To do\nthis, we construct {\\it tessellated} granular metamaterials by joining multiple\nparticle-filled cells together. We focus on cells that contain a small number\nof bidisperse disks in two dimensions. We first study the mechanical properties\nof individual disk-filled cells with three types of boundaries: periodic\nboundary conditions (PBC), fixed-length walls (FXW), and flexible walls (FLW).\nHypostatic jammed packings are found for cells with FLW, but not in cells with\nPBC and FXW, and they are stabilized by quartic modes of the dynamical matrix.\nThe shear modulus of a single cell depends linearly on $p$. We find that the\nslope of the shear modulus with pressure, $\\lambda_c < 0$ for all packings in\nsingle cells with PBC where the number of particles per cell $N \\ge 6$. In\ncontrast, single cells with FXW and FLW can possess $\\lambda_c > 0$, as well as\n$\\lambda_c < 0$, for $N \\le 16$. We show that we can force the mechanical\nproperties of multi-cell granular metamaterials to possess those of single\ncells by constraining the endpoints of the outer walls and enforcing an affine\nshear response. These studies demonstrate that tessellated granular\nmetamaterials provide a novel platform for the design of soft materials with\nspecified mechanical properties."
    },
    {
        "anchor": "Dynamical Self-assembly during Colloidal Droplet Evaporation Studied by\n  in situ Small Angle X-ray Scattering: The nucleation and growth kinetics of highly ordered nanocrystal\nsuperlattices during the evaporation of nanocrystal colloidal droplets was\nelucidated by in situ time resolved small-angle x-ray scattering. We\ndemonstrated for the first time that evaporation kinetics can affect the\ndimensionality of the superlattices. The formation of two-dimensional\nnanocrystal superlattices at the liquid-air interface of the droplet has an\nexponential growth kinetics that originates from interface \"crushing\".",
        "positive": "Can a large packing be assembled from smaller ones?: We consider zero temperature packings of soft spheres, that undergo a jamming\nto unjamming transition as a function of packing fraction. We compare\ndifferences in the structure, as measured from the contact statistics, of a\nfinite subsystem of a large packing to a whole packing with periodic boundaries\nof an equivalent size and pressure. We find that the fluctuations of the\nensemble of whole packings are smaller than those of the ensemble of\nsubsystems. Convergence of these two quantities appears to occur at very large\nsystems, which are usually not attainable in numerical simulations. Finding\ndifferences between packings in two dimensions and three dimensions, we also\nconsider four dimensions and mean-field models, and find that they show similar\nsystem size dependence. Mean-field critical exponents appear to be consistent\nwith the 3d and 4d packings, suggesting they are above the upper critical\ndimension. We also find that the convergence as a function of system size to\nthe thermodynamic limit is characterized by two different length scales. We\nargue that this is the result of the system being above the upper critical\ndimension."
    },
    {
        "anchor": "Modelling ternary fluids in contact with elastic membranes: We present a thermodynamically consistent model of a ternary fluid\ninteracting with elastic membranes. Following a free-energy modelling approach\nand taking into account the thermodynamics laws, we derive the equations\ngoverning the ternary fluid flow and dynamics of the membranes. We also provide\nthe numerical framework for simulating such fluid-structure interaction\nproblems. It is based on the lattice Boltzmann method, employed for resolving\nthe evolution equations of the ternary fluid in an Eulerian description,\ncoupled to the immersed boundary method, allowing for the membrane equations of\nmotion to be solved in a Lagrangian system. The configuration of an elastic\ncapsule placed at a fluid-fluid interface is considered for validation\npurposes. Systematic simulations are performed for a detailed comparison with\nreference numerical results obtained by Surface Evolver, and the Galilean\ninvariance of the proposed model is also proven. The proposed approach is\nversatile, and a wide range of geometries can be simulated. To demonstrate\nthis, the problem of a capillary bridge formed between two deformable capsules\nis investigated here.",
        "positive": "Mechanism of nucleation and growth near the gas-liquid spinodal: Understanding the mechanism of nucleation of the stable phase inside the\nmetastable parent phase during a first order phase transition has been a\nsubject of outstanding interest in natural science. The problem becomes even\nmore challenging as the spinodal is approached. In this work, we have\nundertaken extensive computer simulation studies to probe the molecular\nmechanism for the onset of instability. We have constructed the free energy\nsurfaces of nucleation as a function of multiple reaction coordinates, both for\nsupercooled Lennard-Jones fluid and for 2- and 3-dimensional Ising models.\nWhile the classical Becker-Doring (BD) picture of homogenous nucleation, that\nassumes the growth of a single nucleus by single particle addition, holds good\nat low to moderate supersaturation, the formation of the new stable phase\nbecomes more collective and spread over the whole system at large\nsupersaturation. As the spinodal curve is approached from the coexistence line,\nthe free energy, as a function of the size of the largest liquid-like cluster,\ndevelops a minimum at a sub-critical cluster size. This minimum at intermediate\nsize is responsible for the barrier towards further growth of the nucleus at\nlarge supersaturation. As the spinodal is approached closely, this minimum\ngradually disappears and so does the free energy barrier for the cluster\ngrowth. We find the emergence of an alternative free energy pathway (with a\nbarrier less than that in the BD picture) that involves participation of many\nsub-critical liquid-like clusters and the growth of the stable phase is\npromoted by a coalescence mechanism. Very close to the spinodal the free energy\nsurface becomes quite flat, the significance of a critical nucleus is lost and\nthe classical Becker-Doring picture of nucleation breaks down."
    },
    {
        "anchor": "Crystallization kinetics of binary colloidal monolayers: Experiments and simulations are used to study the kinetics of crystal growth\nin a mixture of magnetic and nonmagnetic particles suspended in ferrofluid. The\ngrowth process is quantified using both a bond order parameter and a mean\ndomain size parameter. The largest single crystals obtained in experiments\nconsist of approximately 1000 particles and form if the area fraction is held\nbetween 65-70% and the field strength is kept in the range of 8.5-10.5 Oe.\nSimulations indicate that much larger single crystals containing as many as\n5000 particles can be obtained in impurity-free conditions within a few hours.\nIf our simulations are modified to include impurity concentrations as small as\n1-2%, then the results agree quantitatively with the experiments. These\nfindings provide an important step toward developing strategies for growing\nsingle crystals that are large enough to enable follow-on investigations across\nmany subdisciplines in condensed matter physics.",
        "positive": "Restricted Dislocation Motion in Crystals of Colloidal Dimer Particles: At high area fractions, monolayers of colloidal dimer particles form a\ndegenerate crystal (DC) structure in which the particle lobes occupy triangular\nlattice sites while the particles are oriented randomly along any of the three\nlattice directions. We report that dislocation glide in DCs is blocked by\ncertain particle orientations. The mean number of lattice constants between\nsuch obstacles is 4.6 +/- 0.2 in experimentally observed DC grains and 6.18 +/-\n0.01 in simulated monocrystalline DCs. Dislocation propagation beyond these\nobstacles is observed to proceed through dislocation reactions. We estimate\nthat the energetic cost of dislocation pair separation via such reactions in an\notherwise defect free DC grows linearly with final separation, hinting that the\nmaterial properties of DCs may be dramatically different from those of 2-D\ncrystals of spheres."
    },
    {
        "anchor": "Electrostatic interactions between discrete helices of charge: We analytically examine the pair interaction for parallel, discrete helices\nof charge. Symmetry arguments allow for the energy to be decomposed into a sum\nof terms, each of which has an intuitive geometric interpretation. Truncated\nFourier expansions for these terms allow for accurate modeling of both the\naxial and azimuthal terms in the interaction energy and these expressions are\nshown to be insensitive to the form of the interaction. The energy is evaluated\nnumerically through application of an Ewald-like summation technique for the\nparticular case of unscreened Coulomb interactions between the charges of the\ntwo helices. The mode structures and electrostatic energies of flexible helices\nare also studied. Consequences of the resulting energy expressions are\nconsidered for both F-actin and A-DNA aggregates.",
        "positive": "Flexible, photonic films of surfactant-functionalized cellulose\n  nanocrystals for pressure and humidity sensing: Most paints contain pigments that absorb light and fade over time. A robust\nalternative can be found in nature, where structural coloration arises from the\ninterference of light with submicron features. Plant-derived, cellulose\nnanocrystals (CNCs) mimic these features by self-assembling into a cholesteric\nliquid crystal that exhibits structural coloration when dried. While much\nresearch has been done on CNCs in aqueous solutions, less is known about\ntransferring CNCs to apolar solvents that are widely employed in paints. This\nstudy uses a common surfactant in agricultural and industrial products to\nsuspend CNCs in toluene that are then dried into structurally colored films.\nSurprisingly, a stable liquid crystal phase is formed within hours, even with\nconcentrations of up to 50 wt.-%. Evaporating the apolar CNC suspensions\nresults in photonic films with peak wavelengths ranging from 660 to 920 nm. The\nresulting flexible films show increased mechanical strength, enabling a\nblue-shift into the visible spectrum with applied force. The films also act as\nhumidity sensors, with increasing relative humidity yielding a red-shift. With\nthe addition of a single surfactant, CNCs can be made compatible with existing\nproduction methods of industrial coatings, while improving the strength and\nresponsiveness of structurally-colored films to external stimuli."
    },
    {
        "anchor": "Mpemba paradox: Hydrogen bond memory and water-skin supersolidity: Numerical reproduction of measurements, experimental evidence for skin\nsuper-solidity and hydrogen-bond memory clarified that Mpemba paradox\nintegrates the heat emission-conduction-dissipation dynamics in the\nsource-path-drain cycle system.",
        "positive": "Active Motion of Janus Particle by Self-thermophoresis in Defocused\n  Laser Beam: We study self-propulsion of a half-metal coated colloidal particle under\nlaser irradiation. The motion is caused by self-thermophoresis: i.e. absorption\nof laser at the metal-coated side of the particle creates local temperature\ngradient which in turn drives the particle by thermophoresis. To clarify the\nmechanism, temperature distribution and a thermal slip flow field around a\nmicro-scale Janus particle are measured for the first time. With measured\ntemperature drop across the particle, the speed of self-propulsion is\ncorroborated with the prediction based on accessible parameters. As an\napplication for driving micro-machine, a micro-rotor heat engine is\ndemonstrated."
    },
    {
        "anchor": "Lateral migration of flexible fibers in Poiseuille flow between two\n  parallel planar solid walls: Dynamics of non-Brownian flexible fibers in Poiseuille flow between two\nparallel planar solid walls is evaluated from the Stokes equations, solved\nnumerically by an accurate multipole code HYDROMULTIPOLE. Fibers migrate\ntowards a critical distance from the wall zc, which depends significantly on\nthe fiber length N and bending stiffness A. Therefore, the calculated values of\nzc can be used to sort fibers. Three modes of the dynamics are found, depending\non a shear-to-bending parameter Gamma. In the first mode, stiff fibers deform\nonly a little and accumulate close to the wall, as the result of a balance\nbetween the tendency to drift away from the channel and the repulsive\nhydrodynamic interaction with the wall. This mechanism is confirmed by\nsimulations in the unbounded Poiseuille flow. In the second mode, flexible\nfibers deform significantly and accumulate far from the wall. In both modes,\nthe tumbling pattern is repeatable. In the third mode, the fibers are even more\ncurved, and their tumbling is irregular.",
        "positive": "Mysteries of supercooled water elucidated by studies of aqueous\n  solutions: The most abundant form of water in the universe probably is its supercooled\nstate, staying non-crystalline down to lowest temperatures. The many\npeculiarities of liquid water, like its partly negative thermal expansion, have\nbeen traced back to prominent anomalies occurring in its supercooled form -\nespecially under elevated pressure - and to the presence of two variants of\nsupercooled water and of amorphous, glassy ice. However, the bare existence of\nthese different liquid states and of a related liquid-liquid crossover at\nambient pressure are controversially debated since decades, just as the\nabsolute value of water's glass-transition temperature. Their direct\nexperimental detection is hampered by the inevitable crystallization of pure\nwater in a certain temperature range, termed \"no-man's land\". To tackle these\nproblems, we have applied dielectric spectroscopy and differential scanning\ncalorimetry to aqueous LiCl solutions. By covering a frequency range of up to\n14 decades and by quenching some of the solutions to avoid crystallization,\nhere we show that there are indeed strong hints at two forms of water,\noccurring in different temperature ranges and having different glass-transition\ntemperatures, even at ambient pressure: A so-called \"fragile\" liquid,\ncharacterized by super-Arrhenius temperature dependence of the molecular\ndynamics at high temperatures, and a \"strong\" liquid, nearly following\nArrhenius behaviour, at low temperatures."
    },
    {
        "anchor": "Bridging the microscopic and the hydrodynamic in active filament\n  solutions: Hydrodynamic equations for an isotropic solution of active polar filaments\nare derived from a microscopic mean-field model of the forces exchanged between\nmotors and filaments. We find that a spatial dependence of the motor stepping\nrate along the filament is essential to drive bundle formation. A number of\ndifferences arise as compared to hydrodynamics derived (earlier) from a\nmesoscopic model where relative filament velocities were obtained on the basis\nof symmetry considerations. Due to the anisotropy of filament diffusion, motors\nare capable of generating net filament motion relative to the solvent. The\neffect of this new term on the stability of the homogeneous state is\ninvestigated.",
        "positive": "Micromechanical description of the compaction of soft pentagon\n  assemblies: We analyze the isotropic compaction of assemblies composed of soft pentagons\ninteracting through classical Coulomb friction via numerical simulations. The\neffect of the initial particle shape is discussed by comparing packings of\npentagons with packings of soft circular particles. We characterize the\nevolution of the packing fraction, the elastic modulus, and the microstructure\n(particle rearrangement, connectivity, contact force and particle stress\ndistributions) as a function of the applied stresses. Both systems behave\nsimilarly; the packing fraction increases and tends asymptotically to a maximum\nvalue $\\phi_{max}$, where the bulk modulus diverges. At the microscopic scale\nwe show that particle rearrangements occur even beyond the jammed state, the\nmean coordination increases as a square root of the packing fraction and, the\nforce and stress distributions become more homogeneous as the packing fraction\nincreases. Soft pentagons present larger particle rearrangements than circular\nones, and such behavior decreases proportionally to the friction.\nInterestingly, the friction between particles also contributes to a better\nhomogenization of the contact force network in both systems. From the\nexpression of the granular stress tensor, we develop a model that describes the\ncompaction behavior as a function of the applied pressure, the Young modulus\nand the initial shape of the particles. This model, settled on the joint\nevolution of the particle connectivity and the contact stress, provides\noutstanding predictions from the jamming point up to very high densities."
    },
    {
        "anchor": "Coupling of elasticity to capillarity in soft aerated materials: We study the elastic properties of soft solids containing air bubbles.\nContrary to standard porous materials, the softness of the matrix allows for a\ncoupling of the matrix elasticity to surface tension forces brought in by the\nbubbles. Thanks to appropriate experiments on model systems, we show how the\nelastic response of the dispersions is governed by two dimensionless\nparameters: the gas volume fraction and a capillary number comparing the\nelasticity of the matrix to the stiffness of the bubbles. We also show that our\nexperimental results are in good agreement with computations of the shear\nmodulus through a micro-mechanical approach.",
        "positive": "Slip and Stress From Low Strain-Rate Nonequilibrium Molecular Dynamics:\n  The Transient-Time Correlation Function Technique: We derive the transient-time correlation function (TTCF) expression for the\ncomputation of phase variables of inhomogenous confined atomistic fluids\nundergoing boundary-driven planar shear (Couette) flow at constant pressure.\nUsing nonequilibrium molecular dynamics simulations, we then apply the TTCF\nformalism to the computation of the shear stress and the slip velocity for\natomistic fluids at realistic low shear rates, in systems under constant\npressure and constant volume. We show that, compared to direct averaging of\nmultiple trajectories, the TTCF method dramatically improves the accuracy of\nthe results at low shear rates, and that it is suitable to investigate the\ntribology and rheology of atomistically detailed confined fluids at realistic\nflow rates."
    },
    {
        "anchor": "Structural transformations of even-numbered n-alkanes confined in\n  mesopores: The n-alkanes C12H26, C14H30, and C16H34 have been imbibed and solidified in\nmesoporous Vycor glass with a mean pore diameter of 10nm. The samples have been\ninvestigated by x-ray diffractometry and calorimetric measurements. The\nstructures and phase sequences have been determined. Apart from a reduction and\nthe hysteresis of the melting/freezing transition, pore confined C12 reproduces\nthe liquid-triclinic phase sequence of the bulk material, but for C16 an\northorhombic rotator mesophase appears that in the bulk state is absent for C16\nbut well known from odd numbered alkanes of similar length. In pore confined\nC14 this phase shows up on cooling but not on heating.",
        "positive": "Scaling behavior of fracture properties of tough adhesive hydrogels: Tough adhesive hydrogels find broad applications in engineering and medicine.\nSuch hydrogels feature high resistance against both cohesion and adhesion\nfailure. The superior fracture properties may, however, deteriorate when the\nhydrogels swell upon exposure of water. The underlying correlation between the\npolymer fraction and fracture properties of tough adhesive hydrogels remains\nlargely unexplored. Here we study how the cohesion and adhesion energies of a\ntough adhesive hydrogel evolve with the swelling process. The results reveal a\nsimilar scaling law of the two quantities on the polymer fraction. Our scaling\nanalysis and computational study reveal that it stems from the scaling of shear\nmodulus. The study will promote the investigation of scaling of hydrogel\nfracture and provide development guidelines for new tough adhesive hydrogels."
    },
    {
        "anchor": "Nonlinearity In A Crosslinked Polyelectric Polypeptide: Youngs modulus of soft solids composed of crosslinked synthetic polypeptides\nhas been determined under different conditions. Co-poly-(L-glutamic acid$_4$,\nL-tyrosine$_1$) [PLEY (4:1)] was crosslinked with poly-L-lysine (PLK) and\n1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Elasticity\nwas assessed by subjecting samples to a compressive strain. Cross-linked\nmaterial at high relative humidity, RH 75-85%, exhibited non-linear elasticity.\nStress-strain response was approximately linear at low strain but nonlinear\nabove a threshold strain. Analysis of the secant modulus revealed apparent\nsoftening of samples at low strain and hardening at high strain, as in\nbiological soft tissues. Fitting stress-strain data with a neo-Hookean model\nyielded approximately 40 $\\le E \\le$ 300 kPa at high RH. Viscoelasticity was\nnonlinear at low RH. The average viscosity-driven relaxation time was 13 min at\nhigh strain and 6 min at low strain. Analysis of the derivative of the secant\nmodulus for non-linear elastic materials revealed a transient response up to a\nstrain of $\\varepsilon \\approx$ 0.18-0.20. Above this range, oscillations\ntended to zero. Non-linear viscoelastic materials showed lower-amplitude\noscillations than samples at high RH up to $\\varepsilon \\approx$ 0.06 and\nstrong damping thereafter. The data suggest that it will be possible to\nengineer mechanical properties of polypeptide materials.",
        "positive": "An alternative, dynamic density functional-like theory for\n  time-dependent density fluctuations in glass-forming fluids: We propose an alternative theory for the relaxation of density fluctuations\nin glass-forming fluids. We derive an equation of motion for the density\ncorrelation function which is local in time and is similar in spirit to the\nequation of motion for the average non-uniform density profile derived within\nthe dynamic density functional theory. We identify the Franz-Parisi free energy\nfunctional as the non-equilibrium free energy for the evolution of the density\ncorrelation function. An appearance of a local minimum of this functional leads\nto a dynamic arrest. Thus, the ergodicity breaking transition predicted by our\ntheory coincides with the dynamic transition of the static approach based on\nthe same non-equilibrium free energy functional."
    },
    {
        "anchor": "A deep learning approach to the structural analysis of proteins: Deep Learning (DL) algorithms hold great promise for applications in the\nfield of computational biophysics. In fact, the vast amount of available\nmolecular structures, as well as their notable complexity, constitutes an ideal\ncontext in which DL-based approaches can be profitably employed. To express the\nfull potential of these techniques, though, it is a prerequisite to express the\ninformation contained in the molecule's atomic positions and distances in a set\nof input quantities that the network can process. Many of the molecular\ndescriptors devised insofar are effective and manageable for relatively small\nstructures, but become complex and cumbersome for larger ones. Furthermore,\nmost of them are defined locally, a feature that could represent a limit for\nthose applications where global properties are of interest. Here, we build a\ndeep learning architecture capable of predicting non-trivial and intrinsically\nglobal quantities, that is, the eigenvalues of a protein's lowest-energy\nfluctuation modes. This application represents a first, relatively simple test\nbed for the development of a neural network approach to the quantitative\nanalysis of protein structures, and demonstrates unexpected use in the\nidentification of mechanically relevant regions of the molecule.",
        "positive": "Pore formation in fluctuating membranes: We study the nucleation of a single pore in a fluctuating lipid membrane,\nspecifically taking into account the membrane fluctuations, as well as the\nshape fluctuations of the pore. For large enough pores, the nucleation free\nenergy is well-described by shifts in the effective membrane surface tension\nand the pore line tension. Using our framework, we derive the stability\ncriteria for the various pore formation regimes. In addition to the well-known\nlarge-tension regime from the classical nucleation theory of pores, we also\nfind a low-tension regime in which the effective line and surface tensions can\nchange sign from their bare values. The latter scenario takes place at\nsufficiently high temperatures, where the opening of a stable pore of finite\nsize is entropically favorable."
    },
    {
        "anchor": "Influence of PEG on the Clustering of Active Janus Colloids: Micrometer scale colloidal particles that propel in a deterministic fashion\nin response to local environmental cues are useful analogs to self-propelling\nentities found in nature. Both natural and synthetic active colloidal systems\nare often near boundaries or are located in crowded environments. Herein, we\ndescribe experiments in which we measured the influence of hydrogen peroxide\nconcentration and dispersed polyethylene glycol (PEG) on the clustering\nbehavior of 5 micrometer catalytic active Janus particles at low concentration.\nWe found the extent to which clustering occurred in ensembles of active Janus\nparticles grew with hydrogen peroxide concentration in the absence of PEG. Once\nPEG was added, clustering was slightly enhanced at low PEG volume fractions,\nbut was reduced at higher PEG volumes fractions. The region in which clustering\nwas mitigated at higher PEG volume fractions corresponded to the region in\nwhich propulsion was previously found to be quenched. Complementary agent based\nsimulations showed that clustering grew with nominal speed. These data support\nthe hypothesis that growth of living crystals is enhanced with increases in\npropulsion speed, but the addition of PEG will tend to mitigate cluster\nformation as a consequence of quenched propulsion at these conditions.",
        "positive": "Block Copolymer at Nano-Patterned Surfaces: We present numerical calculations of lamellar phases of block copolymers at\npatterned surfaces. We model symmetric di-block copolymer films forming\nlamellar phases and the effect of geometrical and chemical surface patterning\non the alignment and orientation of lamellar phases. The calculations are done\nwithin self-consistent field theory (SCFT), where the semi-implicit relaxation\nscheme is used to solve the diffusion equation. Two specific set-ups, motivated\nby recent experiments, are investigated. In the first, the film is placed on\ntop of a surface imprinted with long chemical stripes. The stripes interact\nmore favorably with one of the two blocks and induce a perpendicular\norientation in a large range of system parameters. However, the system is found\nto be sensitive to its initial conditions, and sometimes gets trapped into a\nmetastable mixed state composed of domains in parallel and perpendicular\norientations. In a second set-up, we study the film structure and orientation\nwhen it is pressed against a hard grooved mold. The mold surface prefers one of\nthe two components and this set-up is found to be superior for inducing a\nperfect perpendicular lamellar orientation for a wide range of system\nparameters."
    },
    {
        "anchor": "Why Granular Media Are, After All, Thermal: Granular media are considered \"athermal\", because the grains are too large to\ndisplay Brownian type thermal fluctuations. Yet being macroscopic, every grain\nundergoes thermal expansion, possesses a temperature that may be measured with\na thermometer, and consists of many, many internal degrees of freedom that in\ntheir sum do affect granular dynamics. Therefore, including them in a\ncomprehensive approach to account for granular behavior entails crucial\nadvantages. The pros and cons of thermal versus athermal descriptions are\nconsidered.",
        "positive": "Shape Selection in Chiral Self-Assembly: Many biological and synthetic materials self-assemble into helical or twisted\naggregates. The shape is determined by a complex interplay between elastic\nforces and the orientation and chirality of the constituent molecules. We study\nthis interplay through Monte Carlo simulations, with an accelerated algorithm\nmotivated by the growth of an aggregate out of solution. The simulations show\nthat the curvature changes smoothly from cylindrical to saddle-like as the\nelastic moduli are varied. Remarkably, aggregates of either handedness form\nfrom molecules of a single handedness, depending on the molecular orientation."
    },
    {
        "anchor": "Influence of Confinement on Flow and Lubrication Properties of a Salt\n  Model Ionic Liquid Investigated with Molecular Dynamics: We present a molecular dynamics study of the effects of confinement on the\nlubrication and flow properties of ionic liquids. We use a coarse-grained salt\nmodel description of ionic liquid as a lubricant confined between finite solid\nplates and subjected to two dynamic regimes: shear and cyclic loading. The\nimpact of confinement on the ion arrangement and mechanical response of the\nsystem has been studied in detail and compared to static and bulk properties.\nThe results have revealed that the wall slip has a profound influence on the\nforce built--up as a response to mechanical deformation and that at the same\ntime in the dynamic regime interaction with the walls represents a principal\ndriving force governing the behavior of ionic liquid in the gap. We also\nobserve a transition from a dense liquid to an ordered and potentially\nsolidified state of the ionic liquid taking place under variable normal loads\nand under shear.",
        "positive": "Taming Polar Active Matter with Moving Substrates: Directed Transport\n  and Counterpropagating Macrobands: Following the goal of using active particles as targeted cargo carriers\naimed, for example, to deliver drugs towards cancer cells, the quest for the\ncontrol of individual active particles with external fields is among the most\nexplored topics in active matter. Here, we provide a scheme allowing to control\ncollective behaviour in active matter, focusing on the fluctuating band\npatterns naturally occurring e.g. in the Vicsek model. We show that exposing\nthese patterns to a travelling wave potential tames them, yet in a remarkably\nnontrivial way: the bands, which initially pin to the potential and comove with\nit, upon subsequent collisions, self-organize into a macroband, featuring a\npredictable transport against the direction of motion of the travelling\npotential. Our results provide a route to simultaneously control transport and\nstructure, i.e. micro- versus macrophase separation, in polar active matter."
    },
    {
        "anchor": "Designing patchy interactions to self-assemble arbitrary structures: One of the fundamental goals of nanotechnology is to exploit selective and\ndirectional interactions between molecules to design particles that\nself-assemble into desired structures, from capsids, to nano-clusters, to fully\nformed crystals with target properties (e.g. optical, mechanical, etc.). Here\nwe provide a general framework which transforms the inverse problem of\nself-assembly of colloidal crystals into a Boolean satisfiability problem for\nwhich solutions can be found numerically. Given a reference structure and the\ndesired number of components, our approach produces designs for which the\ntarget structure is an energy minimum, and also allows to exclude solutions\nthat correspond to competing structures. We demonstrate the effectiveness of\nour approach by designing model particles that spontaneously nucleate milestone\nstructures such as the cubic diamond, the pyrochlore and the clathrate\nlattices.",
        "positive": "Parallel flow in Hele-Shaw cells with ferrofluids: Parallel flow in a Hele-Shaw cell occurs when two immiscible liquids flow\nwith relative velocity parallel to the interface between them. The interface is\nunstable due to a Kelvin-Helmholtz type of instability in which fluid flow\ncouples with inertial effects to cause an initial small perturbation to grow.\nLarge amplitude disturbances form stable solitons. We consider the effects of\napplied magnetic fields when one of the two fluids is a ferrofluid. The\ndispersion relation governing mode growth is modified so that the magnetic\nfield can destabilize the interface even in the absence of inertial effects.\nHowever, the magnetic field does not affect the speed of wave propagation for a\ngiven wavenumber. We note that the magnetic field creates an effective\ninteraction between the solitons."
    },
    {
        "anchor": "Equilibration and aging of liquids of non-spherically interacting\n  particles: The non-equilibrium self-consistent generalized Langevin equation theory of\nirreversible processes in liquids is extended to describe the positional and\norientational thermal fluctuations of the instantaneous local concentration\nprofile $n(\\mathbf{r},\\Omega,t)$ of a suddenly-quenched colloidal liquid of\nparticles interacting through non spherically-symmetric pairwise interactions,\nwhose mean value $\\overline{n}(\\mathbf{r},\\Omega,t)$ is constrained to remain\nuniform and isotropic, $\\overline{n}(\\mathbf{r},\\Omega,t)=\\overline{n}(t)$.\nSuch self-consistent theory is cast in terms of the time-evolution equation of\nthe covariance $\\sigma(t)=\\overline{\\delta n_{lm}(\\mathbf{k};t) \\delta\nn^{\\dagger}_{lm}(\\mathbf{k};t)}$ of the fluctuations $\\delta\nn_{lm}(\\mathbf{k};t)=n_{lm}(\\mathbf{k};t) -\\overline{n_{lm}}(\\mathbf{k};t)$ of\nthe spherical harmonics projections $n_{lm}(\\mathbf{k};t)$ of the Fourier\ntransform of $n(\\mathbf{r},\\Omega,t)$. The resulting theory describes the\nnon-equilibrium evolution after a sudden temperature quench of both, the static\nstructure factor projections $S_{lm}(k,t)$ and the two-time correlation\nfunction $F_{lm}(k,\\tau;t)\\equiv\\overline{\\delta n_{lm}(\\mathbf{k},t)\\delta\nn_{lm}(\\mathbf{k},t+\\tau)}$, where $\\tau$ is the correlation \\emph{delay} time\nand $t$ is the \\emph{evolution} or \\emph{waiting} time after the quench. As a\nconcrete and illustrative application we use the resulting self-consistent\nequations to describe the irreversible processes of equilibration or aging of\nthe orientational degrees of freedom of a system of strongly interacting\nclassical dipoles with quenched positional disorder.",
        "positive": "Nonuniform growth and topological defects in the shaping of elastic\n  sheets: Programming the non-uniform growth of a responsive polymer gel has emerged as\na powerful tool to shape sheets into prescribed three dimensional shapes. We\ndemonstrate that shapes with zero Gaussian curvature, except at singularities,\nproduced by the growth-induced buckling of a thin elastic sheet are the same as\nthose produced by the Volterra construction of topological defects in which\nedges of an intrinsically flat surface are identified. With this connection, we\nstudy the problem of choosing an optimal pattern of growth for a prescribed\ndevelopable surface, finding a fundamental trade-off between optimal design and\nthe accuracy of the resulting shape which can be quantified by the length along\nwhich an edge should be identified."
    },
    {
        "anchor": "The vapor-liquid interface potential of (multi)polar fluids and its\n  influence on ion solvation: The interface between the vapor and liquid phase of quadrupolar-dipolar\nfluids is the seat of an electric interfacial potential whose influence on ion\nsolvation and distribution is not yet fully understood. To obtain further\nmicroscopic insight into water specificity we first present extensive classical\nmolecular dynamics simulations of a series of model liquids with variable\nmolecular quadrupole moments that interpolates between SPC/E water and a purely\ndipolar liquid. We then pinpoint the essential role played by the competing\nmultipolar contributions to the vapor-liquid and the solute-liquid interface\npotentials in determining an important ion-specific direct electrostatic\ncontribution to the ionic solvation free energy for SPC/E water---dominated by\nthe quadrupolar and dipolar contributions---beyond the dominant polarization\none. Our results show that the influence of the vapor-liquid interfacial\npotential on ion solvation is strongly reduced due to the strong partial\ncancellation brought about by the competing solute-liquid interface potential.",
        "positive": "Paraffin Wax Crystal Coarsening: Effects of Strains and Wax Crystal\n  Shape: We developed a model of paraffin wax crystal coarsening that well describes\nour experimental results and allows behavior of the paraffin films to be\npredicted on the basis of the extracted kinetic parameters. Wax crystalline\nfilms were evaporated on different substrates (silicon wafer, glass slide, thin\nlayer of gold on silicon), thermally treated at different temperatures, and\ninvestigated by powder X-ray diffraction, high-resolution scanning electron\nmicroscopy, and optical confocal imaging of the surfaces. Preferred (110)\ncrystal orientation of all deposited wax films, independently of substrate\ntype, was observed from the start and increased during heat treatment. The\nchange in preferred orientation was accompanied by changes in crystal\nmorphology and shape, resulting in surface nano-roughening. We modeled the\nprocess as the coarsening of oriented C36H74 crystal islands driven by the\ndecrease in total surface energy. Coarsening kinetics was controlled by\ndiffusion of single molecular chains along the substrate. Evolution of\nnano-roughness during annealing time was well described by a surface coarsening\nlaw. Two additional factors influenced the evolution rate: strains accumulated\nin wax crystals during deposition, and divergence of initial crystal shape from\nthe shape at equilibrium. Both factors lowered activation energy and\neffectively shortened coarsening time."
    },
    {
        "anchor": "Rheology of granular flows across the transition from soft to rigid\n  particles: The rheology of dense granular flows is often seen as dependent on the nature\nof the energy landscape defining the modes of energy relaxation under shear. We\ninvestigate numerically the transition from soft to rigid particles, varying\n$S$, their stiffness compared to the confining pressure over three decades and\nthe inertial number $I$ of the shear flow over five decades. We show that the\nrheological constitutive relation, characterized by a dynamical friction\ncoefficient of the form $\\mu(I)=\\mu_c + a I^{\\alpha}$ is marginally affected by\nthe particle stiffness, with constitutive parameters being essentially\ndependent on the inter-particle friction. Similarly, the distribution of local\nshear rate mostly depends on the inertial number $I$, which shows that the\ncharacteristic timescale of plastic events is primarily controlled by the\nconfining pressure and is insensitive to $S$. By contrast, the form under which\nenergy is stored between these events, but also the contact network properties\nsuch as the coordination number and the distance to isostaticity, are strongly\naffected by stiffness, allowing us to discuss the different regimes in the\n$(S,I)$ phase space.",
        "positive": "Crumpling wires in two dimensions: An energy-minimal simulation is proposed to study the patterns and mechanical\nproperties of elastically crumpled wires in two dimensions. We varied the\nbending rigidity and stretching modulus to measure the energy allocation,\nsize-mass exponent, and the stiffness exponent. The mass exponent is shown to\nbe universal at value $D_{M}=1.33$. We also found that the stiffness exponent\n$\\alpha =-0.25$ is universal, but varies with the plasticity parameters $s$ and\n$\\theta_{p}$. These numerical findings agree excellently with the experimental\nresults."
    },
    {
        "anchor": "Thirty Femtograms Detection of Iron in Mammalian Cells: Inorganic nanomaterials and particles with enhanced optical, mechanical or\nmagnetic attributes are currently being developed for a wide range of\napplications. Safety issues have been formulated however concerning their\npotential cyto- and genotoxicity. For in vivo and in vitro experimentations,\nrecent developments have heightened the need of simple and facile methods to\nmeasure the amount of nanoparticles taken up by cells or tissues. In this work,\nwe present a rapid and highly sensitive method for quantifying the uptake of\niron oxide nanoparticles in mammalian cells. Our approach exploits the\ndigestion of incubated cells with concentrated hydrochloric acid reactant and a\ncolorimetric based UV-Visible absorption technique. The technique allows the\ndetection of iron in cells over 4 decades in masses, from 0.03 to 300 picograms\nper cell. Applied on particles of different surface chemistry and sizes, the\nprotocol demonstrates that the coating is the key parameter in the\nnanoparticle/cell interactions. The data are corroborated by scanning and\ntransmission electron microscopy and stress the importance of resiliently\nadsorbed nanoparticles at the plasma membrane.",
        "positive": "Lattice Boltzmann Simulations of Liquid Crystal Hydrodynamics: We describe a lattice Boltzmann algorithm to simulate liquid crystal\nhydrodynamics. The equations of motion are written in terms of a tensor order\nparameter. This allows both the isotropic and the nematic phases to be\nconsidered. Backflow effects and the hydrodynamics of topological defects are\nnaturally included in the simulations, as are viscoelastic properties such as\nshear-thinning and shear-banding."
    },
    {
        "anchor": "Defects in Crystalline Packings of Twisted Filament Bundles: I.\n  Continuum Theory of Disclinations: We develop the theory of the coupling between in-plane order and out-of-plane\ngeometry in twisted, two-dimensionally ordered filament bundles based on the\nnon-linear continuum elasticity theory of columnar materials. We show that\ntwisted textures of filament backbones necessarily introduce stresses into the\ncross-sectional packing of bundles and that these stresses are formally\nequivalent to the geometrically-induced stresses generated in thin elastic\nsheets that are forced to adopt spherical curvature. As in the case of\ncrystalline order on curved membranes, geometrically-induced stresses couple\nelastically to the presence of topological defects in the in-plane order. We\nderive the effective theory of multiple disclination defects in the cross\nsection of bundle with a fixed twist and show that above a critical degree of\ntwist, one or more 5-fold disclinations is favored in the elastic energy ground\nstate. We study the structure and energetics of multi-disclination packings\nbased on models of equilibrium and non-equilibrium cross-sectional order.",
        "positive": "Bidimensional fluid system with competing interactions: In this paper we present a study of pattern formation in bidimensional\nsystems with competing short-range attractive and long-range repulsive\ninteractions. The interaction parameters are chosen in such a way to analyse\ntwo different situations: the spontaneous pattern formation due to the presence\nof strong competing interactions on different length scales and the pattern\nformation as a response to an external modulating potential when the system is\nclose to its Lifshitz point. We compare different Monte Carlo techniques\nshowing that Parallel Tempering technique represents a promising approach to\nstudy such systems and we present detailed results for the specific heat and\nthe structural properties. We also present random phase approximation\npredictions about the spontaneous pattern formation (or microphase separation),\nas well as linear response theory predictions about the induced pattern\nformation due to the presence of an external modulating field. In particular we\nobserve that the response of our systems to external fields is much stronger\ncompared to the response of a Lennard-Jones fluid."
    },
    {
        "anchor": "X-ray cross-correlation analysis of liquid crystal membranes in the\n  vicinity of hexatic-smectic phase transition: We present an x-ray study of liquid crystal membranes in the vicinity of\nhexatic-smectic phase transition by means of angular x-ray cross-correlation\nanalysis (XCCA). By applying two-point angular intensity cross-correlation\nfunctions to the measured series of diffraction patterns the parameters of\nbond-orientational (BO) order in hexatic phase were directly determined. The\ntemperature dependence of the positional correlation lengths was analyzed as\nwell. The obtained correlation lengths show larger values for the higher-order\nFourier components of BO order. These findings indicate a strong coupling\nbetween BO and positional order that has not been studied in detail up to now.",
        "positive": "Nonlinear response theory for Markov processes: Simple models for glassy\n  relaxation: The theory of nonlinear response for Markov processes obeying a master\nequation is formulated in terms of time-dependent perturbation theory for the\nGreen's functions and general expressions for the response functions up to\nthird order in the external field are given. The nonlinear response is\ncalculated for a model of dipole reorientations in an asymmetric double well\npotential, a standard model in the field of dielectric spectroscopy. The static\nnonlinear response is finite with the exception of a certain temperature $T_0$\ndetermined by the value of the asymmetry. In a narrow temperature range around\n$T_0$, the modulus of the frequency-dependent cubic response shows a peak at a\nfrequency on the order of the relaxation rate and it vanishes for both, low\nfrequencies and high frequencies. At temperatures at which the static response\nis finite (lower and higher than $T_0$), the modulus is found to decay\nmonotonously from the static limit to zero at high frequencies. In addition,\nresults of calculations for a trap model with a Gaussian density of states are\npresented. In this case, the cubic response depends on the specific dynamical\nvariable considered and also on the way the external field is coupled to the\nkinetics of the model. In particular, a set of different dynamical variables is\nconsidered that gives rise to identical shapes of the linear susceptibility and\nonly to different temperature dependencies of the relaxation times. It is found\nthat the frequency dependence of the nonlinear response functions, however,\nstrongly depends on the particular choice of the variables. The results are\ndiscussed in the context of recent theoretical and experimental findings\nregarding the nonlinear response of supercooled liquids and glasses."
    },
    {
        "anchor": "The Electrostatic Persistence Length of Polymers beyond the OSF Limit: We use large scale Monte Carlo simulations to test scaling theories for the\nelectrostatic persistence length $l_e$ of isolated, uniformly charged polymers\nwith \\DH intrachain interactions in the limit where the screening length\n$\\kappa^{-1}$ exceeds the intrinsic persistence length of the chains. Our\nsimulations cover a significantly larger part of the parameter space than\nprevious studies. We observe no significant deviations from the prediction\n$l_e\\propto\\kappa^{-2}$ by Khokhlov and Khachaturian which is based on applying\nthe Odijk-Skolnick-Fixman theory to the stretched de\nGennes-Pincus-Velasco-Brochard polyelectrolyte blob chain. A linear or\nsublinear dependence of the persistence length on the screening length can be\nruled out. We argue that previous numerical results pointing into this\ndirection are probably due to a combination of excluded volume and finite chain\nlength effects. The paper emphasizes the role of scaling arguments in the\ndevelopment of useful representations for experimental and simulation data.",
        "positive": "Rheology of active suspensions with hydrodynamic interactions: Using a simple model of self-propelled particle, the effective shear\nviscosity of a dilute, spatially homogeneous suspension of active particles is\nstudied. We use formulation of non-linear Fokker-Planck equation to drive a\nkinetic description, including the effect of external flow field, rotary\ndiffusion, and particle-particle hydrodynamic interactions in two dimensions.\nAnalytical expressions are obtained for the stress tensor at small Peclet\nnumbers, in a simple shear flow, up to second order of volume fraction of the\nswimmers, which shows the explicit dependence of shear viscosity on the details\nof the swimming mechanism."
    },
    {
        "anchor": "First-order layering and critical wetting transitions in non-additive\n  hard sphere mixtures: Using fundamental-measure density functional theory we investigate entropic\nwetting in an asymmetric binary mixture of hard spheres with positive\nnon-additivity. We consider a general planar hard wall, where preferential\nadsorption is induced by a difference in closest approach of the different\nspecies and the wall. Close to bulk fluid-fluid coexistence the phase rich in\nthe minority component adsorbs either through a series of first-order layering\ntransitions, where an increasing number of liquid layers adsorbs sequentially,\nor via a critical wetting transition, where a thick film grows continuously.",
        "positive": "Role of Gaussian curvature on local equilibrium and dynamics of\n  smectic-isotropic interfaces: Recent research on interfacial instabilities of smectic films has shown\nunexpected morphologies that are not fully explained by classical local\nequilibrium thermodynamics. Annealing focal conic domains can lead to conical\npyramids, changing the sign of the Gaussian curvature, and exposing smectic\nlayers at the interface. In order to explore the role of the Gaussian curvature\non the stability and evolution of the film-vapor interface, we introduce a\nphase field model of a smectic-isotropic system as a first step in the study.\nThrough asymptotic analysis of the model, we generalize the classical condition\nof local equilibrium, the Gibbs-Thomson equation, to include contributions from\nsurface bending and torsion, and a dependence on the layer orientation at the\ninterface. A full numerical solution of the phase field model is then used to\nstudy the evolution of focal conic structures in smectic domains in contact\nwith the isotropic phase via local evaporation and condensation of smectic\nlayers. As in experiments, numerical solutions show that pyramidal structures\nemerge near the center of the focal conic owing to evaporation of adjacent\nsmectic planes and to their orientation relative to the interface. Near the\ncenter of the focal conic domain, a correct description of the motion of the\ninterface requires the additional curvature terms obtained in the asymptotic\nanalysis, thus clarifying the limitations in modeling motion of hyperbolic\nsurfaces solely driven by mean curvature."
    },
    {
        "anchor": "Perspective: Surface Freezing in Water: A Nexus of Experiments and\n  Simulations: Surface freezing is a phenomenon in which crystallization is enhanced at a\nvapor-liquid interface. In some systems, such as $n$-alkanes, this enhancement\nis dramatic, and results in the formation of a crystalline layer at the free\ninterface even at temperatures slightly above the equilibrium bulk freezing\ntemperature. There are, however, systems in which the enhancement is purely\nkinetic, and only involves faster nucleation at or near the interface. The\nfirst, thermodynamic, type of surface freezing is easier to confirm in\nexperiments, requiring only the verification of the existence of crystalline\norder at the interface. The second, kinetic, type of surface freezing is far\nmore difficult to prove experimentally. One material that is suspected of\nundergoing the second type of surface freezing is liquid water. Despite strong\nindications that the freezing of liquid water is kinetically enhanced at\nvapor-liquid interfaces, the findings are far from conclusive, and the topic\nremains controversial. In this perspective, we present a simple thermodynamic\nframework to understand conceptually and distinguish these two types of surface\nfreezing. We then briefly survey fifteen years of experimental and\ncomputational work aimed at elucidating the surface freezing conundrum in\nwater.",
        "positive": "Monomer distributions and intra-chain collisions of a polymer confined\n  to a channel: We study the conformations of a self-avoiding polymer confined to a channel\nby computing the cross-sectional distributions of the positions of its\nmonomers. By means of Monte-Carlo simulations for a self-avoiding,\nfreely-jointed chain we determine how the cross-sectional distribution for a\ngiven monomer depends on its location in the polymer, and how strongly this\ndistribution is affected by self avoidance. To this end we analyze how the\nfrequency of intra-chain collisions between monomers depends on their spatial\nposition in the channel and on their location within the polymer. We show that\nmost collisions occur between closely neighboring monomers. As a consequence\nthe collision probability depends only weakly on the spatial position of the\nmonomers. Our results explain why the effect of self-avoidance on the monomer\ndistributions is weaker than predicted by mean-field theory. We discuss the\nrelevance of our results for studies of DNA conformations in nanofluidic\nchannels."
    },
    {
        "anchor": "The Topological Origin of the Peierls-Nabarro Barrier: Crystals and other condensed matter systems described by density waves often\nexhibit dislocations. Here we show, by considering the topology of the ground\nstate manifolds (GSMs) of such systems, that dislocations in the density phase\nfield always split into disclinations, and that the disclinations themselves\nare constrained to sit at particular points in the GSM. Consequently, the\ntopology of the GSM forbids zero-energy dislocation glide, giving rise to a\nPeirels-Nabarro barrier.",
        "positive": "Stress Transmission through Three-Dimensional Ordered Granular Arrays: We measure the local contact forces at both the top and bottom boundaries of\nthree-dimensional face-centered-cubic and hexagonal-close-packed granular\ncrystals in response to an external force applied to a small area at the top\nsurface. Depending on the crystal structure, we find markedly different results\nwhich can be understood in terms of force balance considerations in the\nspecific geometry of the crystal. Small amounts of disorder are found to create\nadditional structure at both the top and bottom surfaces."
    },
    {
        "anchor": "Evolutionary strategy for inverse charge measurements of dielectric\n  particles: We report a computational strategy to obtain the charges of individual\ndielectric particles from experimental observation of their interactions as a\nfunction of time. This strategy uses evolutionary optimization to minimize the\ndifference between trajectories extracted from experiment and simulated\ntrajectories based on many-particle force fields. The force fields include both\nCoulombic interactions and dielectric polarization effects that arise due to\nparticle-particle charge mismatch and particle-environment dielectric contrast.\nThe strategy was applied to systems of free falling charged granular particles\nin vacuum, where electrostatic interactions are the only driving forces that\ninfluence the particles' motion. We show that when the particles' initial\npositions and velocities are known, the optimizer requires only an initial and\nfinal particle configuration of a short trajectory in order to accurately infer\nthe particles' charges; when the initial velocities are unknown and only the\ninitial positions are given, the optimizer can learn from multiple frames along\nthe trajectory to determine the particles' initial velocities and charges.\nWhile the results presented here offer a proof-of-concept demonstration of the\nproposed ideas, the proposed strategy could be extended to more complex systems\nof electrostatically charged granular matter.",
        "positive": "Mechanical characterization of brain tissue in simple shear at dynamic\n  strain rates: During severe impact conditions, brain tissue experiences a rapid and complex\ndeformation, which can be seen as a mixture of compression, tension and shear.\nMoreover, diffuse axonal injury (DAI) occurs in animals and humans when both\nthe strains and strain rates exceed 10% and 10/s, respectively. Knowing the\nmechanical properties of brain tissue in shear at these strains and strain\nrates is thus of particular importance, as they can be used in finite element\nsimulations to predict the occurrence of brain injuries under different impact\nconditions. In this research, an experimental setup was developed to perform\nsimple shear tests on porcine brain tissue at strain rates < 120/s. The maximum\nmeasured shear stress at strain rates of 30, 60, 90 and 120/s was 1.15 +/- 0.25\nkPa, 1.34 +/- 0.19 kPa, 2.19 +/- 0.225 kPa and 2.52 +/- 0.27 kPa, (mean +/-\nSD), respectively, at the maximum amount of shear, K = 1. Good agreement of\nexperimental, theoretical (Ogden and MooneyRivlin models) and numerical shear\nstresses was achieved (p = 0.7866 - 0.9935). Specimen thickness effects (2.0 -\n10.0 mm thick specimens) were also analyzed numerically and we found that there\nis no significant difference (p = 0.9954) in the shear stress magnitudes,\nindicating a homogeneous deformation of the specimens during simple shear\ntests. Stress relaxation tests in simple shear were also conducted at different\nstrain magnitudes (10% - 60% strain) with the average rise time of 14 ms. This\nallowed us to estimate elastic and viscoelastic parameters (mu = 4942.0 Pa and\nProny parameters: g1 = 0.520, g2 = 0.3057, tau1 = 0.0264 s, tau2 = 0.011 s)\nthat can be used in FE software to analyze the hyperviscoelastic behavior of\nbrain tissue."
    },
    {
        "anchor": "Dissipative particle dynamics with energy conservation: isoenergetic\n  integration and transport properties: Simulations of nano- to micro-meter scale fluidic systems under thermal\ngradients require consistent mesoscopic methods accounting for both\nhydrodynamic interactions and proper transport of energy. One such method is\ndissipative particle dynamics with energy conservation (DPDE), which has been\nused for various fluid systems with non-uniform temperature distributions.\nDespite the success of the method, existing integration algorithms have shown\nto result in an undesired energy drift, putting into question whether the DPDE\nmethod properly captures properties of real fluids. We propose a modification\nof the velocity-Verlet algorithm with local energy conservation for each DPDE\nparticle, such that the total energy is conserved up to machine precision.\nFurthermore, transport properties of a DPDE fluid are analyzed in detail. In\nparticular, an analytical approximation for the thermal conductivity\ncoefficient is derived, which allows the selection of a specific value a\npriori. Finally, we provide approximate expressions for the dimensionless\nPrandtl and Schmidt numbers, which characterize fluid transport properties and\ncan be adjusted independently by a proper selection of model parameters, and\ntherefore, made comparable with those of real fluids. In conclusion, our\nresults strengthen the DPDE method as a very robust approach for the\ninvestigation of mesoscopic systems with temperature inhomogeneities.",
        "positive": "A Model for Thermodynamic Properties of Monoatomic Liquids: We present an analytical model for calculating the thermodynamic properties\nof monoatomic liquids using a rough potential energy surface (PES). The PES is\ntransformed into an equivalent simple harmonic oscillator. Without employing\nany adjustable parameters, the model agrees closely with experimental entropy,\nheat capacity, and latent heat of fusion and vaporization data for monatomic\nliquids. In addition, it offers a simple, physical explanation for Richard\nMelting rule, and provides a material-dependent correction to Trouton\nVaporization rule."
    },
    {
        "anchor": "Third virial coefficient for 4-arm and 6-arm star polymers: We discuss the computation of the third virial coefficient in polymer\nsystems, focusing on an additional contribution absent in the case of\nmonoatomic fluids. We determine the interpenetration ratio and several\nquantities that involve the third virial coefficient for star polymers with 4\nand 6 arms in the good-solvent regime, in the limit of a large degree of\npolymerization.",
        "positive": "Dynamical density functional theory for colloidal particles with\n  arbitrary shape: Starting from the many-particle Smoluchowski equation, we derive dynamical\ndensity functional theory for Brownian particles with an arbitrary shape. Both\npassive and active (self-propelled) particles are considered. The resulting\ntheory constitutes a microscopic framework to explore the collective dynamical\nbehavior of biaxial particles in nonequilibrium. For spherical and uniaxial\nparticles, earlier derived dynamical density functional theories are recovered\nas special cases. Our study is motivated by recent experimental progress in\npreparing colloidal particles with many different biaxial shapes."
    },
    {
        "anchor": "Thomson problem in the disk: We investigate the classical ground state of a large number of charges\nconfined inside a disk and interacting via the Coulomb potential. By realizing\nthe important role that the peripheral charges play in determining the lowest\nenergy solutions, we have successfully implemented an algorithm that allows us\nto work with configurations with a desired number of border charges. This\nfeature brings a consistent reduction in the computational complexity of the\nproblem, thus simplifying the search of global minima of the energy.\nAdditionally, we have implemented a divide and conquer approach which has\nallowed us to study configurations of size never reached before (the largest\none corresponding to $N=40886$ charges). These last configurations, in\nparticular, are seen to display an increasingly rich structure of topological\ndefects as $N$ gets larger.",
        "positive": "Soft matter and fractional mathematics: insights into mesoscopic quantum\n  and time-space structures: Recent years have witnessed a great research boom in soft matter physics. by\nnow, most advances, however, are of either empirical results or purely\nmathematical extensions. The major obstacle is lacking of insights into\nfundamental phsysical laws underlying fractal mesostructures of soft matter.\nThis study will use fractional mathematics, which consists of fractal,\nfractional calculus, fractional Brownian motion, and Levy stable distribution,\nto examine mesoscopic quantum mechanics and time-space structures governing\n\"anomalous\" behaviors of soft matter. Our major results include fractional\nPlanck quantum energy relationship, fractional phonon, and time-space scaling\ntransform."
    },
    {
        "anchor": "Adhesive forces inhibit underwater contact formation for a soft-hard\n  collision: Thermodynamics tells us to expect underwater contact between two hydrophobic\nsurfaces to result in stronger adhesion compared to two hydrophilic surfaces.\nHowever, presence of water changes not only energetics, but also the dynamic\nprocess of reaching a final state, which couples solid deformation and liquid\nevacuation. These dynamics can create challenges for achieving strong\nunderwater adhesion/friction, which affects diverse fields including soft\nrobotics, bio-locomotion and tire traction. Closer investigation, requiring\nsufficiently precise resolution of film evacuation while simultaneously\ncontrolling surface wettability has been lacking. We perform high resolution\nin-situ frustrated total internal reflection imaging to track underwater\ncontact evolution between soft-elastic hemispheres of varying stiffness and\nsmooth-hard surfaces of varying wettability. Surprisingly, we find exponential\nrate of water evacuation from hydrophobic-hydrophobic (adhesive) contact is 3\norders of magnitude lower than that from hydrophobic-hydrophilic (non-adhesive)\ncontact. The trend of decreasing rate with decreasing wettability of glass\nsharply changes about a point where thermodynamic adhesion crosses zero,\nsuggesting a transition in mode of evacuation, which is illuminated by\n3-Dimensional spatiotemporal heightmaps. Adhesive contact is characterized by\nthe early localization of sealed puddles, whereas non-adhesive contact remains\nsmooth, with film-wise evacuation from one central puddle. Measurements with a\nhuman thumb and alternatively hydrophobic/hydrophilic glass surface demonstrate\npractical consequences of the same dynamics: adhesive interactions cause\ninstability in valleys and lead to a state of more trapped water and less\nintimate solid-solid contact.",
        "positive": "An Incremental Contact Model for Rough Surfaces of Strain Hardening\n  Solids: The load-area relation of rough surfaces is of great interest in tribology.\nFor elastic-plastic solids with strain hardening, an incremental model is\nadopted to analyze the contact of rough surfaces, in which the contact is\nmodeled by accumulation of equivalent circular contacts with varying radius.\nFor three typical rough surfaces with various material properties, comparisons\nwith direct finite element calculations demonstrate the efficiency of this\nincremental contact model. An approximate linear relation between load and\ncontact area is predicted by both methods up to a contact fraction of 15%. The\ninfluence of yield stress and strain hardening index on the load-area\nproportionality is presented. This work gives a simple while effective method\nto calculate the load-area relation for rough contact of strain hardening\nmaterials."
    },
    {
        "anchor": "Crystallization of hard-sphere glasses: We study by molecular dynamics the interplay between arrest and\ncrystallization in hard spheres. For state points in the plane of volume\nfraction ($0.54 \\leq phi \\leq 0.63$) and polydispersity ($0 \\leq s \\leq\n0.085$), we delineate states that spontaneously crystallize from those that do\nnot. For noncrystallizing (or precrystallization) samples we find\nisodiffusivity lines consistent with an ideal glass transition at $\\phi_g\n\\approx 0.585$, independent of $s$. Despite this, for $s<0.05$, crystallization\noccurs at $\\phi > \\phi_g$. This happens on time scales for which the system is\naging, and a diffusive regime in the mean square displacement is not reached;\nby those criteria, the system is a glass. Hence, contrary to a widespread\nassumption in the colloid literature, the occurrence of spontaneous\ncrystallization within a bulk amorphous state does not prove that this state\nwas an ergodic fluid rather than a glass.",
        "positive": "Equilibrium of fluid membranes with tangent-plane order (TPO),\n  elasticity of smectics with TPO, and dispiration asymmetry in smectics-C*: Fluid membranes endowed with tangent-plane order (TPO) such as tilt- and\nhexatic order afford unique soft matter systems for investigating the interplay\nbetween elasticity, shape, topology, and thermal fluctuations. Using the\nspin-connection formulation of membrane energy we obtain equa- tions of\nequilibrium together with free boundary conditions for ground states of such\nmembranes. We extend the spin-connection formulation to smectic liquid crystals\nwith TPO and show that for chiral smectics-C* this generalization leads to\nexperimentally verifiable consequences for dispirations having topological\nindices (helicities) of the same magnitude but opposite signs."
    },
    {
        "anchor": "Mesh update techniques for free-surface flow solvers using spectral\n  element method: This paper presents a novel mesh-update technique for unsteady free-surface\nNewtonian flows using spectral element method and relying on the arbitrary\nLagrangian--Eulerian kinematic description for moving the grid. Selected\nresults showing compatibility of this mesh-update technique with spectral\nelement method are given.",
        "positive": "Nonaffine deformation and tunable yielding of colloidal assemblies at\n  the air-water interface: Silica nanoparticles trapped at air-water interface form a 2D solid state\nwith amorphous order. We propose a theoretical model to describe how this\nsolid-like state deforms under a shear strain ramp up to and beyond a yielding\npoint which leads to plastic flow. The model accounts for all the\nparticle-level and many-body physics of the system: nonaffine displacements,\nlocal connectivity and its evolution in terms of cage-breaking, and\ninterparticle interactions mediated by the particle chemistry and colloidal\nforces. The model is able to reproduce experimental data with only two\nnon-trivial fitting parameters: the relaxation time of the cage and the viscous\nrelaxation time. The interparticle spring constant contains information about\nthe strength of interparticle bonding which is tuned by the amount of\nsurfactant that renders the particles hydrophobic and mutually attractive. This\nframework opens up the possibility of quantitatively tuning and rationally\ndesigning the mechanical response of colloidal assemblies at the air-water\ninterface. Also, it provides a mechanistic explanation to the observed\nnon-monotonic dependence of yield strain on surfactant concentration."
    },
    {
        "anchor": "Buckling of semiflexible filaments under compression: A model for filament buckling at finite temperatures is presented. Starting\nfrom the classical worm-like chain model under constant compression, we use a\nmean-field approach for filament inextensibility to find the complete partition\nfunction. We find that there is a simple interpolation formula that describes\nthe free energy of chains or filaments as a function of end-to-end separation,\nwhich spans the whole range of filament stiffnesses. Using this formula we\nstudy the buckling transition of semiflexible filaments and find that kinetics\nplays an important role. We propose that the filament buckling is essentially\nthe first order transition governed by the kinetics of escaping a local free\nenergy minimum. A simple model for the kinetics is put forward, which shows the\ncritical buckling force for a filament is reduced by a fraction that has a\nuniversal scaling with temperature with an exponent 0.56.",
        "positive": "Heterogeneous Dynamics in Columnar Liquid Crystals of Parallel Hard Rods: In the wake of previous studies on the rattling-and-jumping diffusion in\nsmectic liquid crystal phases of colloidal rods, we analyze here for the first\ntime the heterogeneous dynamics in columnar phases. More specifically, we\nperform computer simulations to investigate the relaxation dynamics of a binary\nmixture of perfectly aligned hard spherocylinders. We detect that the columnar\narrangement of the system produces free-energy barriers the particles should\novercome to jump from one column to another, thus determining a hopping-type\ndiffusion. This phenomenon accounts for the non-Gaussian inter-column diffusion\nand shows a two-step structural relaxation which is remarkably analogous to\nthat of out-of-equilibrium glass-forming systems and gels. Surprisingly enough,\nslight deviations from the behavior of simple liquids due to transient cages is\nalso observed in the direction perpendicular to this plane, where the system is\nusually referred to as liquid-like."
    },
    {
        "anchor": "Transverse Instability of Avalanches in Granular Flows down Incline: Avalanche experiments on an erodible substrate are treated in the framework\nof ``partial fluidization'' model of dense granular flows. The model identifies\na family of propagating soliton-like avalanches with shape and velocity\ncontrolled by the inclination angle and the depth of substrate. At high\ninclination angles the solitons display a transverse instability, followed by\ncoarsening and fingering similar to recent experimental observation. A primary\ncause for the transverse instability is directly related to the dependence of\nsoliton velocity on the granular mass trapped in the avalanche.",
        "positive": "Landau theory-based estimates for viscosity coefficients of uniaxial and\n  biaxial nematic liquid crystals: Using Landau theory, it is shown that eight phenomenological parameters are\nneeded to describe and distinguish the twelve viscosity coefficients of a\nbiaxial nematic phase, or the five viscosity coefficients of a uniaxial nematic\nphase. The dependence of the coefficients on the macroscopic uniaxial and\nbiaxial order parameters is established. Since these order parameters are\ndetermined by the anisotropies of the dielectric constant, we show that it\nshould be possible to determine values for all eight of the phenomenological\nparameters of the theory from measurements of the temperature dependence of the\nfive viscosities of a uniaxial phase."
    },
    {
        "anchor": "Large deformation electrohydrodynamics of a Skalak elastic capsule in AC\n  electric field: The axisymmetric electrohydrodynamic deformation of an elastic capsule with\ncapacitive membrane obeying Skalak law under uniform AC electric field is\ninvestigated using analytical and boundary integral theory. The low capillary\nnumber (the ratio of destabilizing shear or electric force to the stabilizing\nelastic force) regime shows time-averaged prolate and oblate spheroid\ndeformations, and the time-periodic prolate-sphere, oblate-sphere breathing\nmodes are commensurate with the time averaged-deformation. A novel\nprolate-oblate breathing mode is observed due to an interplay of finite\nmembrane charging time and the field reversal of the AC field. The study, when\nextended to high capillary number, shows new breathing modes of\ncylinder-prolate, cylinder-oblate, and biconcave-prolate deformation. These are\nthe results of highly compressive normal Maxwell stress at the poles and are\naided by weak compressive equatorial stress, characteristic of a capacitive\nmembrane. The findings of this work should form the basis for the understanding\nof more complex biological cells and synthetic capsules for industrial\napplications.",
        "positive": "Properties of surface Landau-de Gennes Q-tensor models: Uniaxial nematic liquid crystals whose molecular orientation is subjected to\na tangential anchoring on a curved surface offer a non trivial interplay\nbetween the geometry and the topology of the surface and the orientational\ndegree of freedom. We consider a general thin film limit of a Landau-de Gennes\nQ-tensor model which retains the characteristics of the 3D model. From this,\npreviously proposed surface models follow as special cases. We compare\nfundamental properties, such as alignment of the orientational degrees of\nfreedom with principle curvature lines, order parameter symmetry and phase\ntransition type for these models, and suggest experiments to identify proper\nmodel assumptions."
    },
    {
        "anchor": "Crater Depth Prediction in Granular Collisions: A Uniaxial Compression\n  Model: Impact crater experiments in granular media traditionally involve loosely\npacked sand targets. However, this study investigates granular impact craters\non both loosely and more tightly packed sand targets. We report granular vs.\ngranular experiments that consistently adhere to power-law scaling laws for\ndiameter as a function of impacting energy, similar to those reported by other\ngroups for their experiments utilizing both solid and granular projectiles. In\ncontrast, we observe significant deviations in the depth vs. energy power-law\npredicted by previous models. To address this discrepancy, we introduce a\nphysical model of uniaxial compression that explains how depth saturates in\ngranular collisions. Furthermore, we present an energy balance alongside this\nmodel that aligns well with our crater volume measurements and describes the\nenergy transfer mechanisms acting during crater formation. Central peak\nformation also plays an essential role in better transferring vertical momentum\nto horizontal degrees of freedom, resulting in shallow craters on compacted\nsandbox targets. Our results reveal a depth-to-diameter aspect ratio of\napproximately $\\sim 1/5$, allowing us to interpret the shallowness of planetary\ncraters in light of the uniaxial compression mechanism proposed in this work.",
        "positive": "Anomalous diffusion in polydisperse granular gases: Monte Carlo\n  simulations: We perform a direct Monte Carlo simulation of the diffusion in a\nmulticomponent granular medium. We investigate the diffusion coefficients and\nmean-squared displacements of granular particles in a polydisperse granular gas\nin a homogeneous cooling state containing an arbitrary number of species of\ndifferent sizes and masses using both models of constant and time-dependent\nrestitution coefficients. In our study, we used a powerful low-rank algorithm\nthat allows for efficient simulation of highly polydisperse granular systems.\nMean square displacements in Monte Carlo simulations are in good agreement with\ntheoretical predictions."
    },
    {
        "anchor": "Periodic, quasi-periodic, fractal, Kolakoski and random binary polymers:\n  Energy structure and carrier transport: We study periodic, quasi-periodic (Thue-Morse, Fibonacci, Period Doubling,\nRudin-Shapiro), fractal (Cantor, generalized Cantor), Kolakoski and random\nbinary sequences using a tight-binding wire model, where a site is a monomer\n(e.g., in DNA, a base pair). We use B-DNA as our prototype system. All\nsequences have purines, guanine (G) or adenine (A) on the same strand, i.e.,\nour prototype binary alphabet is (G,A). Our aim is to examine the influence of\nsequence intricacy and magnitude of parameters on energy structure,\nlocalization and charge transport. We study quantities such as autocorrelation\nfunction, eigenspectra, density of states, Lyapunov exponents, transmission\ncoefficients and current-voltage curves. We show that the degree of sequence\nintricacy and the presence of correlations decisively affect the aforementioned\nphysical properties. Periodic segments have enhanced transport properties.\nSpecifically, in homogeneous sequences transport efficiency is maximum. There\nare several deterministic aperiodic sequences that can support significant\ncurrents, depending on the Fermi level of the leads. Random sequences is the\nless efficient category.",
        "positive": "Correlating toughness and roughness in ductile fracture: Three dimensional calculations of ductile crack growth under mode I plane\nstrain, small scale yielding conditions are carried out using an\nelastic-viscoplastic constitutive relation for a progres- sively cavitating\nplastic solid with two populations of void nucleating second phase particles.\nFull field solutions are obtained for three dimensional material\nmicrostructures characterized by ran- dom distributions of void nucleating\nparticles. Crack growth resistance curves and fracture surface roughness\nstatistics are calculated using standard procedures. The range of void\nnucleating particle volume fractions considered give rise to values of\ntoughness, JIC, that vary by a factor of four. For all volume fractions\nconsidered, the computed fracture surfaces are self-affine over a size range of\nabout two orders of magnitude with a roughness exponent of 0.54 $\\pm$ 0.03. For\nsmall void nucleating particle volume fractions, the mean large particle\nspacing serves as a single dominant length scale. In this regime, the\ncorrelation length of the fracture surface corresponding to the cut-off of the\nself-affine behavior is found to be linearly related to JIC thus quantitatively\ncorrelating toughness and fracture surface roughness."
    },
    {
        "anchor": "Characterizing Surface Wetting and Interfacial Properties using Enhanced\n  Sampling (SWIPES): We introduce an accurate and efficient method for characterizing surface\nwetting and interfacial properties, such as the contact angle made by a liquid\ndroplet on a solid surface, and the vapor-liquid surface tension of a fluid.\nThe method makes use of molecular simulations in conjunction with the indirect\numbrella sampling technique to systematically wet the surface and estimate the\ncorresponding free energy. To illustrate the method, we study the wetting of a\nfamily of Lennard-Jones surfaces by water. We estimate contact angles for\nsurfaces with a wide range of attractions for water by using our method and\nalso by using droplet shapes. Notably, as surface-water attractions are\nincreased, our method is able to capture the transition from partial to\ncomplete wetting. Finally, the method is straightforward to implement and\ncomputationally efficient, providing accurate contact angle estimates in\nroughly 5 nanoseconds of simulation time.",
        "positive": "Dynamics of the fast component of nano-confined water under electric\n  field: We report the diffusion of water molecules confined in the pores of folded\nsilica materials (FSM-12 with average pore diameter of $\\sim$ 16 \\AA), measured\nby means of quasielastic neutron scattering using the cold neutron chopper\nspectrometer (CNCS). The goal is to investigate the effect of electric field on\nthe previously observed fast component of nano-confined water. The measurements\nwere taken at temperatures between 220 K and 245 K, and at two electric field\nvalues, 0 kV/mm and 2 kV/mm. Similar to the recently observed electric field\ninduced enhancement of the slow translational motion of confined water, there\nis a an equally important impact of the field on the faster diffusion."
    },
    {
        "anchor": "Active Darcy's Law: While bacterial swarms can exhibit active turbulence in vacant spaces, they\nnaturally inhabit crowded environments. We numerically show that driving\ndisorderly active fluids through porous media enhances Darcy's law. While\npurely active flows average to zero flux, hybrid active/driven flows display\ngreater drift than pure-driven fluids. This enhancement is non-monotonic with\nactivity, leading to an optimal activity to maximize flow rate. We incorporate\nthe active contribution into an active Darcy's law, which may serve to help\nunderstand anomalous transport of swarming in porous media.",
        "positive": "Arm retraction dynamics in dense polymer brushes: Large scale Monte Carlo simulations of dense layers of grafted polymer chains\nin good solvent conditions are used to explore the relaxation of a polymer\nbrush. Monomer displacements are analyzed for the directions parallel and\nperpendicular to the grafting plane. Auto-correlation functions of individual\nsegments or chain sections are monitored as function of time. We demonstrate\nthat the terminal relaxation time $\\tau$ of grafted layers well in the brush\nregime grows exponentially with degree of polymerization $N$ of the chains,\n$\\tau\\propto N^{3}\\exp(N/N_{e})$, with $N_{e}$ the entanglement degree of\npolymerization in the brush. One specific feature of entangled polymer brushes\nis that the late time relaxation of the perpendicular component coincides for\nall segments. We use this observation to extract the terminal relaxation time\nof an entangled brush."
    },
    {
        "anchor": "Elastic monopoles and external torques in nematic liquid crystal\n  colloids: Up to now it is commonly believed that a colloidal particle suspended in a\nnematic liquid crystal never produces elastic monopoles because this violates\nthe mechanical equilibrium condition. And the only way to obtain deformations\nof director field falling off with distance as r^{-1} is to exert an external\ntorque \\Gamma_{ext} on the colloid \\cite{de_Gennes}. In this paper we\ndemonstrate that this statement is not quite correct and elastic monopoles, as\nwell as dipoles and quadrupoles, can be induced without any external influence\njust by the particle itself. A behavior of a spherical colloidal particle with\nasymmetric anchoring strength distribution is considered theoretically. It is\ndemonstrated that such a particle when suspended in a nematic host can produce\ndirector deformations decreasing as $r^{-1}$, i.e. elastic monopoles, by itself\nwithout any external influence.",
        "positive": "A thin film model for corotational Jeffreys fluids under strong slip: We derive a thin film model for viscoelastic liquids under strong slip which\nobey the stress tensor dynamics of corotational Jeffreys fluids."
    },
    {
        "anchor": "Granular segregation in dense systems: the role of statistical mechanics\n  and entropy: Granular segregation is ubiquitous in industrial, geological or daily-life\ncontext, but there is still no unifying theoretical approach. In this review,\nwe examine two examples of granular segregation -- shallow rapid flows and\nrotating drums -- which suggest that the dynamics of systems at intermediate\nand high density might be amenable to a statistical mechanics approach.",
        "positive": "Time-Resolved Mechanical Spectroscopy of Soft Materials via Optimally\n  Windowed Chirps: The ability to measure the bulk dynamic behavior of soft materials with\ncombined time- and frequency-resolution is instrumental for improving our\nfundamental understanding of connections between the microstructural dynamics\nand the macroscopic mechanical response. Current state-of-the-art techniques\nare often limited by a compromise between resolution in the time and frequency\ndomain, mainly due to the use of elementary input signals that have not been\ndesigned for fast time-evolving systems such as materials undergoing gelation,\ncuring or self-healing. In this work, we develop an optimized and robust\nexcitation signal for time-resolved mechanical spectroscopy through the\nintroduction of joint frequency- and amplitude-modulated exponential chirps.\nInspired by the biosonar signals of bats and dolphins, we optimize the signal\nprofile to maximize the signal-to-noise ratio while minimizing spectral leakage\nwith a carefully-designed modulation of the envelope of the chirp. A combined\nexperimental and numerical investigation reveals that there exists an optimal\nrange of window profiles that minimizes the error with respect to standard\nsingle frequency sweep methods. The minimum error is set by the noise floor of\nthe instrument, suggesting that the accuracy of an optimally windowed chirp\nsignal is directly comparable to that achievable with a standard frequency\nsweep, while the acquisition time can be reduced by up to two orders of\nmagnitude, for comparable spectral content. Finally, we demonstrate the ability\nof this optimized signal to provide time- and frequency-resolved rheometric\ndata by studying the fast gelation process of an acid-induced protein gel. The\nuse of optimally windowed chirps enables a robust rheological characterization\nof a wide range of soft materials undergoing rapid mutation and has the\npotential to become an invaluable tool for researchers across different\ndisciplines."
    },
    {
        "anchor": "Behavior of confined granular beds under cyclic thermal loading: We investigate the mechanical behavior of a confined granular packing of\nirregular polyhedral particles under repeated heating and cooling cycles by\nmeans of numerical simulations with the Non-Smooth Contact Dynamics method.\nAssuming a homogeneous temperature distribution as well as constant temperature\nrate, we study the effect of the container shape, and coefficients of thermal\nexpansions on the pressure buildup at the confining walls and the density\nevolution. We observe that small changes in the opening angle of the\nconfinement can lead to a drastic peak pressure reduction. Furthermore, the\ndisplacement fields over several thermal cycles are obtained and we discover\nthe formation of convection cells inside the granular material having the shape\nof a torus. The root mean square of the vorticity is then calculated from the\ndisplacement fields and a quadratic dependency on the ratio of thermal\nexpansion coefficients is established.",
        "positive": "A new method for measurement and quantification of tracer diffusion in\n  nanoconfined liquids: We report development of a novel instrument to measure tracer diffusion in\nwater under nano-scale confinement. A direct optical access to the confinement\nregion, where water is confined between a tapered fiber and a flat substrate,\nis made possible by coating the probe with metal and opening a small aperture(\n0.1 $\\mu$m to 1 $\\mu$m) at its end. A well-controlled cut using an ion beam\nensures desired lateral confinement area as well as adequate illumination of\nthe confinement gap. The probe is mounted on a tuning-fork based force sensor\nto control the separation between the probe and the substrate with nm\nprecision. Fluctuations in fluorescence intensity due to diffusion of a dye\nmolecule in water confined between probe and the sample are recorded using a\nconfocal arrangement with a single photon precision. A Monte-Carlo method is\ndeveloped to determine the diffusion coefficient from the measured\nautocorrelation of intensity fluctuations which accommodates the specific\ngeometry of confinement and the illumination profile. The instrument allows\nmeasurement of diffusion laws under confinement. We found that the diffusion of\na tracer molecule is slowed down by more than ten times for the probe-substrate\nseparations of 5 nm and below."
    },
    {
        "anchor": "Numerical modeling of non-woven fiber mats: Numerical simulations on non-woven-fibrous, porous structures were performed\nto determine material design space for energy storage device (battery and\nultracapacitor) separators.",
        "positive": "Transition in heterogeneous dynamics across the morphological hierarchy\n  in two-dimensional aggregates: Two-dimensional (2D) particulate aggregates formed due to competing\ninteractions exhibit a range of non-equilibrium steady state morphologies from\nfinite-size compact crystalline structures to non-compact string-like\nconformations. We report a transition in heterogeneous microscopic dynamics\nacross this morphological hierarchy as a function of decreasing long-range\nrepulsion relative to short-range attraction at a constant {\\it low} density\nand temperature. Following a very slow cooling protocol to form steady state\naggregates, we show that geometric frustration inherent to competing\ninteractions assures non-ergodicity of the system, which in turn results in\nlong-time sub diffusive relaxation of the same. Analysing individual particle\ntrajectories generated by molecular dynamics, we identify {\\it caging} dynamics\nof particles in compact clusters in contrast to the {\\it bonding} scenario for\nnon-compact ones. Finally, by monitoring temperature dependence, we present a\ngeneric relation between diffusivity and structural randomness of the\naggregates, irrespective of their thermodynamic equilibrium."
    },
    {
        "anchor": "Influence of confinement on granular penetration by impact: We study experimentally the influence of confinement on the penetration depth\nof impacting spheres into a granular medium contained in a finite cylindrical\nvessel. The presence of close lateral walls reduces the penetration depth, and\nthe characteristic distance for these lateral wall effects is found to be of\nthe order of one sphere diameter. The influence of the bottom wall is found to\nhave a much shorter range.",
        "positive": "Criticality in strongly correlated fluids: In this brief review I will discuss criticality in strongly correlated\nfluids. Unlike simple fluids, molecules of which interact through short ranged\nisotropic potential, particles of strongly correlated fluids usually interact\nthrough long ranged forces of Coulomb or dipolar form. While for simple fluids\nmechanism of phase separation into liquid and gas was elucidated by van der\nWaals more than a century ago, the universality class of strongly correlated\nfluids, or in some cases even existence of liquid-gas phase separation remains\nuncertain."
    },
    {
        "anchor": "Understanding water's anomalies with locally favored structures: Water is a complex structured liquid of hydrogen-bonded molecules that\ndisplays a surprising array of unusual properties, also known as water\nanomalies, the most famous being the density maximum at about $4^\\circ$C. The\norigin of these anomalies is still a matter of debate, and so far a\nquantitative description of water's phase behavior starting from the molecular\narrangements is still missing. Here we provide a simple physical description\nfrom microscopic data obtained through computer simulations. We introduce a\nnovel structural order parameter, which quantifies the degree of translational\norder of the second shell, and show that this parameter alone, which measures\nthe amount of locally favored structures, accurately characterizes the state of\nwater. A two-state modeling of these microscopic structures is used to describe\nthe behavior of liquid water over a wide region of the phase diagram, correctly\nidentifying the density and compressibility anomalies, and being compatible\nwith the existence of a second critical point in the deeply supercooled region.\nFurthermore, we reveal that locally favored structures in water not only have\ntranslational order in the second shell, but also contain five-membered rings\nof hydrogen-bonded molecules. This suggests their mixed character: the former\nhelps crystallization, whereas the latter causes frustration against\ncrystallization.",
        "positive": "Nonequilibrium pattern formation in chiral Langmuir monolayers with\n  transmembrane flows: Nonequilibrium Langmuir monolayers including a fraction of chiral molecules\nand subject to transmembrane flow are considered. The flow induces coherent\ncollective precession of chiral molecules. Our theoretical study shows that\nsplay interactions in this system lead to spatial redistribution of chiral\nmolecules and formation of spiral waves and target patterns observed in\nexperiments."
    },
    {
        "anchor": "Flow and structure of fluids in functionalized nanopores: We investigate through non-equilibrium Molecular Dynamics simulations the\nstructure and flow of fluids in functionalized nanopores. The nanopores are\nmodeled as cylindrical structures with solvophilic and solvophobic sites. Two\nfluids are modeled. The first is a standard Lennard Jones fluid. The second one\nis modeled with a isotropic two-length scale potential, which exhibits in bulk\nwater-like anomalies. Our results indicates distinct dependence of the overall\nmass flux for each species of fluid with the number of solvophilic sites for\ndifferent nanotubes radii. Also, the density and fluid structure are dependent\nfrom the nanotube radius and the solvophilic properties of the nanotube. This\nindicates that the presence of a second length scale in the fluid-fluid\ninteraction will lead to distinct behavior. Also, our results shows that\nchemically functionalized nanotubes with different radius will have distinct\nnano-fluidic features. Our results are explained in the basis of the\ncharacteristic scale fluid properties and the effects of nanoconfinement.",
        "positive": "Observation of non-local dielectric relaxation in glycerol: Since its introduction, liquid viscosity and relaxation time $\\tau$ have been\nconsidered to be an intrinsic property of the system that is essentially local\nin nature and therefore independent of system size. We perform dielectric\nrelaxation experiments in glycerol, and find that this is the case at high\ntemperature only. At low temperature, $\\tau$ increases with system size and\nbecomes non-local. We discuss the origin of this effect in a picture based on\nliquid elasticity length, the length over which local relaxation events in a\nliquid interact via induced elastic waves, and find good agreement between\nexperiment and theory."
    },
    {
        "anchor": "Interaction Between Motor Domains Can Explain the Complex Dynamics of\n  Heterodimeric Kinesins: Motor proteins are active enzyme molecules that play a crucial role in many\nbiological processes. They transform the chemical energy into the mechanical\nwork and move unidirectionally along rigid cytoskeleton filaments.\nSingle-molecule experiments suggest that motor proteins, consisting of two\nmotor domains, move in a hand-over-hand mechanism when each subunit changes\nbetween trailing and leading positions in alternating steps, and these subunits\ndo not interact with each other. However, recent experiments on heterodimeric\nkinesins suggest that the motion of motor domains is not independent, but\nrather strongly coupled and coordinated, although the mechanism of these\ninteractions are not known. We propose a simple discrete stochastic model to\ndescribe the dynamics of homodimeric and heterodimeric two-headed motor\nproteins. It is argued that interactions between motor domains modify free\nenergy landscapes of each motor subunit, and motor proteins still move via the\nhand-over-hand mechanism but with different transitions rates. Our calculations\nof biophysical properties agree with experimental observations. Several ways to\ntest the theoretical model are proposed.",
        "positive": "A new dielectric effect in viscous liquids: An accurate experimental and theoretical study has been performed about a\nphenomenon, not previously reported in the literature, occurring in highly\nviscous liquids: the formation of a definite pipe structure induced by the\npassage of a heavy body, this structure lasting for quite a long time. A very\nrich phenomenology (including mechanical, optical and structural effects)\nassociated with the formation of the pipe has been observed in different\nliquids. Actually, the peculiar dynamical evolution of that structure does not\nappear as a trivial manifestation of standard relaxation or spurious effects.\nIn particular we have revealed different time scales during the evolution of\nthe pipe and a non-monotonous decrease of the persistence time with decreasing\nviscosity (with the appearance of at least two different maxima). We put\nforward a microscopic model, consistent with the experimental data, where the\npipe behaves as a \"dielectric shell\" whose time evolution is described through\na simple thermodynamical approach, predicting several properties effectively\nobserved."
    },
    {
        "anchor": "Neutron diffraction of hydrogenous materials: measuring incoherent and\n  coherent intensities separately from liquid water - a 40-year-old puzzle\n  solved: (short version) Accurate determination of the coherent static structure\nfactor of disordered materials containing proton nuclei is prohibitively\ndifficult by neutron diffraction, due to the large incoherent cross section of\n$^1$H. This notorious problem has set severe obstacles to the structure\ndetermination of hydrogenous materials up to now, via introducing large\nuncertainties into neutron diffraction data processing. Here we present the\nfirst accurate separate measurements, using polarized neutron diffraction, of\nthe coherent and incoherent contributions to the total static structure factor\nof 5 mixtures of light and heavy water, over an unprecedentedly wide momentum\ntransfer range. The structure factors of H$_2$O and D$_2$O mixtures derived in\nthis work may signify the beginning of a new era in the structure determination\nof hydrogenous materials, using neutron diffraction.",
        "positive": "Effective temperature and jamming transition in dense, gently sheared\n  granular assemblies: We present extensive computational results for the effective temperature,\ndefined by the fluctuation-dissipation relation between the mean square\ndisplacement and the average displacement of grains, under the action of a\nweak, external perturbation, of a sheared, bi-disperse granular packing of\ncompressible spheres. We study the dependence of this parameter on the shear\nrate and volume fractions, the type of particle and the observable in the\nfluctuation-dissipation relation. We find the same temperature for different\ntracer particles in the system. The temperature becomes independent on the\nshear rate for slow enough shear suggesting that it is the effective\ntemperature of the jammed packing. However, we also show that the agreement of\nthe effective temperature for different observables is only approximate, for\nvery long times, suggesting that this defintion may not capture the full\nthermodynamics of the system. On the other hand, we find good agreement between\nthe dynamical effective temperature and a compactivity calculated assuming that\nall jammed states are equiprobable. Therefore, this definition of temperature\nmay capture an instance of the ergodic hypothesis for granular materials as\nproposed by theoretical formalisms for jamming. Finally, our simulations\nindicate that the average shear stress and apparent shear viscosity follow the\nusual relation with the shear rate for complex fluids. Our results show that\nthe application of shear induces jamming in packings whose particles interact\nby tangential forces."
    },
    {
        "anchor": "Emergent Self-organization in Active Materials: Biological systems exhibit large-scale self-organized dynamics and structures\nwhich enable organisms to perform the functions of life. The field of active\nmatter strives to develop and understand microscopically-driven nonequilibrium\nmaterials, with emergent properties comparable to those of living systems. This\nreview will describe two recently developed classes of active matter systems,\nin which simple building blocks --- self-propelled colloidal particles or\nextensile rod-like particles --- self-organize to form macroscopic structures\nwith features not possible in equilibrium systems. We summarize the recent\nexperimental and theoretical progress on each of these systems, and we present\nsimple descriptions of the physics underlying their emergent behaviors.",
        "positive": "Global Defect Topology in Nematic Liquid Crystals: We give the global homotopy classification of nematic textures for a general\ndomain with weak anchoring boundary conditions and arbitrary defect set in\nterms of twisted cohomology, and give an explicit computation for the case of\nknotted and linked defects in $\\mathbb{R}^3$, showing that the distinct\nhomotopy classes have a 1-1 correspondence with the first homology group of the\nbranched double cover, branched over the disclination loops. We show further\nthat the subset of those classes corresponding to elements of order 2 in this\ngroup have representatives that are planar and characterise the obstruction for\nother classes in terms of merons. The planar textures are a feature of the\nglobal defect topology that is not reflected in any local characterisation.\nFinally, we describe how the global classification relates to recent\nexperiments on nematic droplets and how elements of order 4 relate to the\npresence of $\\tau$ lines in cholesterics."
    },
    {
        "anchor": "Reversal of Solvent Migration in Poroelastic Folds: Polymer networks and biological tissues are often swollen by a solvent, such\nthat their properties emerge from a coupling between swelling and elastic\nstress. This poroelastic coupling becomes particularly intricate in wetting,\nadhesion, and creasing, for which sharp folds appear that can even lead to\nphase separation. Here we resolve the singular nature of poroelastic surface\nfolds and determine the solvent distribution in the vicinity of the fold-tip.\nSurprisingly, two opposite scenarios emerge depending on the angle of the fold.\nIn obtuse folds such as creases, it is found that the solvent is completely\nexpelled near the crease-tip, according to a nontrivial spatial distribution.\nFor wetting ridges with acute fold angles, the solvent migration is reversed as\ncompared to creasing, and the degree of swelling is maximal at the fold-tip. We\ndiscuss how our poroelastic fold-analysis offers an explanation for phase\nseparation, fracture and contact angle hysteresis.",
        "positive": "Dynamically Heterogeneous Relaxation of Entangled Polymer Chains: Stress relaxation following deformation of an entangled polymeric liquid is\nthought to be affected by transient reforming of chain entanglements. In this\nwork, we use single molecule techniques to study the relaxation of individual\npolymers in the transition regime from unentangled to entangled solutions. Our\nresults reveal the emergence of dynamic heterogeneity underlying polymer\nrelaxation behavior, including distinct molecular sub-populations described by\na single-mode and a double-mode exponential relaxation process. The slower\ndouble-mode timescale $\\tau_{d,2}$ is consistent with a characteristic\nreptation time, whereas the single-mode timescale $\\tau_s$ and the fast\ndouble-mode timescale $\\tau_{d,1}$ are attributed to local regions of transient\ndisentanglement due to deformation."
    },
    {
        "anchor": "Spreading law on a completely wettable spherical substrate: The energy\n  balance approach: The spreading of a cap-shaped spherical droplet on a completely wettable\nspherical substrate is studied. The non-equilibrium thermodynamic formulation\nis used to derive the thermodynamic driving force of spreading including the\nline-tension effect. Then the energy balance approach is adopted to derive the\nevolution equation of the spreading droplet. The time evolution of the contact\nangle $\\theta$ of a droplet obeys a power law $\\theta \\sim t^{-\\alpha}$ with\nthe exponent $\\alpha$, which is different from that derived from Tanner's law\non a flat substrate. Furthermore, the line tension must be positive to promote\ncomplete wetting on a spherical substrate, while it must be negative on a flat\nsubstrate.",
        "positive": "Pattern formation in odd viscoelastic fluids: Non-reciprocal interactions fueled by local energy consumption can be found\nin biological and synthetic active matter at scales where viscoelastic forces\nare important. Such systems can be described by \"odd\" viscoelasticity, which\nassumes fewer material symmetries than traditional theories. Here we study odd\nviscoelasticity analytically and using lattice Boltzmann simulations. We\nidentify a pattern-forming instability which produces an oscillating array of\nfluid vortices, and we elucidate which features govern the growth rate,\nwavelength, and saturation of the vortices. Our observation of pattern\nformation through odd mechanical response can inform models of biological\npatterning and guide engineering of odd dynamics in soft active matter systems."
    },
    {
        "anchor": "Classical Hydrodynamics for Analogue Spacetimes: Open Channel Flows and\n  Thin Films: Here we review the way to build analogue spacetimes in open channel flows by\nlooking at the flow phase diagram and the corresponding analogue experiments\nperformed during the last years in the associated flow regimes. Thin films like\nthe circular jump with different dispersive properties are discussed with the\nintroduction of a brand new system for the next generation of analogue gravity\nexperiments: flowing soap films with their capillary/elastic waves.",
        "positive": "Delocalization of interacting directed polymers on a periodic substrate:\n  Localization length and critical exponents from non-Hermitian spectra: We study a classical model of thermally fluctuating polymers confined to two\ndimensions, experiencing a grooved periodic potential, and subject to pulling\nforces both along and transverse to the grooves. The equilibrium polymer\nconformations are described by a mapping to a quantum system with a\nnon-Hermitian Hamiltonian and with fermionic statistics generated by\nnoncrossing interactions among polymers. Using molecular dynamics simulations\nand analytical calculations, we identify a localized and a delocalized phase of\nthe polymer conformations, separated by a delocalization transition which\ncorresponds (in the quantum description) to the breakdown of a band insulator\nwhen driven by an imaginary vector potential. We calculate the average tilt of\nthe many-body system, at arbitrary shear values and filling density of polymer\nchains, in terms of the complex-valued non-Hermitian band structure. We find\nthe critical shear value, the localization length, and the critical exponent by\nwhich the shear modulus diverges in terms of the branch points (exceptional\npoints) in the band structure at which the bandgap closes. We also investigate\nthe combined effects of non-Hermitian delocalization and localization due to\nboth periodicity and disorder, uncovering preliminary evidence that while\ndisorder favours localization at high values, it encourages delocalization at\nlower values."
    },
    {
        "anchor": "Network formation and relaxation dynamics in a new model for colloidal\n  gelation: We investigate the gel formation from the equilibrium sol phase in a simple\nmodel that has the characteristics of (colloidal) gel-forming systems at a\nfinite temperature. At low volume fraction and low temperatures, particles are\nlinked by long-living bonds and form an open percolating network. By means of\nmolecular dynamics simulations, we study the lifetime of bonds and nodes of the\ngel network in order to relate these quantities to the complex relaxation\ndynamics observed.",
        "positive": "Measurement of the temperature decrease in evaporating soap films: Recent advances have demonstrated that evaporation can play a significant\nrole on soap film stability, which is a key concern in many industrial areas\nbut also for children playing with bubbles. Thus, evaporation leads to a film\nthinning but also to a film cooling, which has been overlooked for soapy\nobjects. Here, we study the temperature variation of an evaporating soap film\nfor different values of relative humidity and glycerol concentrations. We\nevidence that the temperature of soap films can decrease after their creation\nup to 8$~^\\text{o}$C. We propose a model describing the temperature drop of\nsoap films after their formation that is in quantitative agreement with our\nexperiments. We emphasize that this cooling effect is significant and must be\ncarefully considered in future studies on the dynamics of soap films."
    },
    {
        "anchor": "Dynamics of active filaments in porous media: The motion of active polymers in a porous medium is shown to depend\ncritically on flexibilty, activity and degree of polymerization. For given\nPeclet number, we observe a transition from localisation to diffusion as the\nstiffness of the chains is increased. Whereas stiff chains move almost\nunhindered through the porous medium, flexible ones spiral and get stuck. Their\nmotion can be accounted for by the model of a continuous time random walk with\na renewal process corresponding to unspiraling. The waiting time distribution\nis shown to develop heavy tails for decreasing stiffness, resulting in\nsubdiffusive and ultimately caged behaviour.",
        "positive": "A direct quantitative measure of surface mobility in a glassy polymer: Thin polymer films have striking dynamical properties that differ from their\nbulk counterparts. With the simple geometry of a stepped polymer film on a\nsubstrate, we probe mobility above and below the glass transition temperature\n$T_{\\textrm{g}}$. Above $T_{\\textrm{g}}$ the entire film flows, while below\n$T_{\\textrm{g}}$ only the near surface region responds to the excess\ninterfacial energy. An analytical thin film model for flow limited to the free\nsurface region shows excellent agreement with sub-$T_{\\textrm{g}}$ data. The\nsystem transitions from whole film flow to surface localized flow over a narrow\ntemperature region near the bulk $T_{\\textrm{g}}$. The experiments and model\nprovide a measure of surface mobility in a sample geometry where confinement\nand substrate effects are negligible. This fine control of the glassy rheology\nis of key interest to nanolithography among numerous other applications."
    },
    {
        "anchor": "Modeling of the bending of an electroactive pseudo trilayer based on\n  PEDOT, a semiconductor polymer: Electroactive polymers (EAP) are smart materials that can be used as\nactuators, sensors or energy harvesters in many fields. We had previously\nstudied an ionic metal-polymer composites (IPMC), which consists in an ionic\npolymer film such as Nafion saturated with water and coated on both sides with\na thin layer of metal acting as electrodes. This system bends when it is\nsubject to an electric field orthogonal to the film and can thus be used as an\nactuator. Conversely, the deflection of the film generates a potential\ndifference between the electrodes ; the same system can therefore be used as a\nsensor.We have developed a ''continuous medium'' model for this system. The\nthermodynamics of linear irreversible processes had enabled us to establish its\nconstitutive equations.We are currently interested in a system of close\nproperties based on PEDOT, a semiconductor EAP. The central part of the device\nconsists in two interpenetrating polymers playing the role of an ions\nreservoir. The PEDOT is polymerized on each side and forms an interpenetrating\nnetwork with the two other polymers. A pseudo trilayer is obtained, the two\nouter layers containing the PEDOT acting as electrodes. It is then saturated\nwith an ionic liquid. When the blade thus obtained is placed in an electric\nfield orthogonal to its faces, the PEDOT undergoes a reduction reaction (or\ndedoping) on the side of the negative electrode, which attracts cations from\nthe central part and therefore swells ; the blade ultimately bends towards the\npositive electrode.We have first adapted our model to this two-components\nsystem : the cations on the one hand, and the three polymers and the anions on\nthe other hand. We have written its balance equations and thermodynamic\nrelations first at the microscopic scale for each phase, then at the\nmacroscopic scale for the whole material using an averaging technique. The\nthermodynamics of linear irreversible processes then provides its constitutive\nrelations : a Kelvin - Voigt type stress-strain relation and generalized\nFourier's and Darcy's laws. The equations obtained were applied to the case of\na cantilevered blade subject to a continuous potential difference at constant\ntemperature. The numerical resolution of the equations system enabled us to\ndraw the profiles of the different quantities, which are very steep functions\nnear the electrodes. We also evaluated the tip displacement and the force that\nmust be exerted on the free end of the beam to prevent its displacement\n(blocking force). The results obtained are in good agreement with the\nexperimental data published in the literature.",
        "positive": "Fluid depletion in shear bands: How does pore liquid reconfigure within shear bands in wet granular media?\nConventional wisdom predicts that liquid is drawn into dilating granular media.\nWe, however, find a depletion of liquid in shear bands despite increased\nporosity due to dilatancy. This apparent paradox is resolved by a microscale\nmodel for liquid transport at low liquid contents induced by rupture and\nreconfiguration of individual liquid bridges. Measured liquid content profiles\nshow macroscopic depletion bands similar to results of numerical simulations.\nWe derive a modified diffusion description for rupture-induced liquid\nmigration."
    },
    {
        "anchor": "Vapour-Liquid Coexistence of an Active Lennard-Jones fluid: We study a three-dimensional system of self-propelled Lennard-Jones particles\nusing Brownian Dynamics simulations. Using recent theoretical results for\nactive matter, we calculate the pressure and report equations of state for the\nsystem. Additionally, we chart the vapour-liquid coexistence and show that the\ncoexistence densities can be well described using simple power laws. Lastly, we\ndemonstrate that our out-of-equilibrium system shows deviations from both the\nlaw of rectilinear diameters and the law of corresponding states.",
        "positive": "Two phase transitions in the two-dimensional nematic 3-vector model with\n  no quasi long-range order: Monte Carlo simulation of the density of states: The presence of stable topological defects in a two-dimensional (\\textit{d} =\n2) liquid crystal model allowing molecular reorientations in three dimensions\n(\\textit{n} = 3) was largely believed to induce defect-mediated\nBerzenskii-Kosterlitz-Thouless (BKT) type transition to a low temperature phase\nwith quasi long-range order. However, earlier Monte Carlo (MC) simulations\ncould not establish certain essential signatures of the transition, suggesting\nfurther investigations. We study this model by computing its equilibrium\nproperties through MC simulations, based on the determination of the density of\nstates of the system. Our results show that, on cooling, the high temperature\ndisordered phase deviates from its initial progression towards the topological\ntransition, crossing over to a new fixed point, condensing into a nematic phase\nwith exponential correlations of its director fluctuations. The thermally\ninduced topological kinetic processes continue, however limited to the length\nscales set by the nematic director fluctuations, and lead to a second\ntopological transition at a lower temperature. We argue that in the (\\textit{d}\n= 2, \\textit{n} = 3) system with a biquadratic Hamiltonian, the presence of\nadditional molecular degree of freedom and local $Z_{2}$ symmetry associated\nwith lattice sites, together promote the onset of an additional relevant\nscaling field at matching length scales in the high temperature region, leading\nto a crossover."
    },
    {
        "anchor": "Lagrangian 3D tracking of fluorescent microscopic objects in motion: We describe the development of a tracking device, mounted on an\nepi-fluorescent inverted microscope, suited to obtain time resolved 3D\nLagrangian tracks of fluorescent passive or active micro-objects in\nmicro-fluidic devices. The system is based on real-time image processing,\ndetermining the displacement of a x,y mechanical stage to keep the chosen\nobject at a fixed position in the observation frame. The z displacement is\nbased on the refocusing of the fluorescent object determining the displacement\nof a piezo mover keeping the moving object in focus. Track coordinates of the\nobject with respect to the micro-fluidic device, as well as images of the\nobject are obtained at a frequency of several tenths of Hertz. This device is\nparticularly well adapted to obtain trajectories of motile micro-organisms in\nmicro-fluidic devices with or without flow.",
        "positive": "Kinetic Monte Carlo Simulations for Birefringence Relaxation of\n  Photo-Switchable Molecules on a Surface: Recent experiments have demonstrated that in a dense monolayer of\nphoto-switchable dye Methyl-Red molecules the relaxation of an initial\nbirefringence follows a power-law decay, typical for glass-like dynamics. The\nslow relaxation can efficiently be controlled and accelerated by illuminating\nthe monolayer with circularly polarized light, which induces trans-cis\nisomerization cycles. To elucidate the microscopic mechanism, we develop a\ntwo-dimensional molecular model in which the trans and cis isomers are\nrepresented by straight and bent needles, respectively. As in the experimental\nsystem, the needles are allowed to rotate and to form overlaps but they cannot\ntranslate. The out-of-equilibrium rotational dynamics of the needles is\ngenerated using kinetic Monte Carlo simulations. We demonstrate that, in a\nregime of high density and low temperature, the power-law relaxation can be\ntraced to the formation of spatio-temporal correlations in the rotational dy-\nnamics, i.e., dynamic heterogeneity. We also show that the nearly isotropic cis\nisomers can prevent dynamic heterogeneity from forming in the monolayer and\nthat the relaxation then becomes exponential."
    },
    {
        "anchor": "Tuning electrostatic interactions of colloidal particles at oil-water\n  interfaces with organic salts: Monolayers of colloidal particles at oil-water interfaces readily crystalize\nowing to electrostatic repulsion, which is often mediated through the oil.\nHowever, little attempts exist to control it using oil-soluble electrolytes. We\nprobe the interactions amongst charged hydrophobic micospheres confined at a\nwater/hexadecane interface and show that repulsion can be continuously tuned\nover orders of magnitude upon introducing minor amounts of an organic salt into\nthe oil. Our results show that charged groups at the particle/oil interface are\nsubject to an associative discharging mechanism, analogous to the charge\nregulation kinetics observed for charged colloids in non-polar solvents.",
        "positive": "Force networks and the dynamic approach to jamming in sheared granular\n  media: Diverging correlation lengths on either side of the jamming transition are\nused to formulate a rheological model of granular shear flow, based on the\npropagation of stress through force chain networks. The model predicts three\ndistinct flow regimes, characterized by the shear rate dependence of the stress\ntensor, that have been observed in both simulations and experiments. The\nboundaries separating the flow regimes are quantitatively determined and\ntestable. In the limit of jammed granular solids, the model predicts the\nobserved anomalous scaling of the shear modulus and a new relation for the\nshear strain at yield."
    },
    {
        "anchor": "Packing of elastic rings with friction: We study the deformations of elastic filaments confined within\nslowly-shrinking circular boundaries, under contact forces with friction. We\nperform computations with a spring-lattice model that deforms like a thin\ninextensible filament of uniform bending stiffness. Early in the deformation,\ntwo lobes of the filament make contact. If the friction coefficient is small\nenough, one lobe slides inside the other; otherwise, the lobes move together or\none lobe bifurcates the other. There follows a sequence of deformations that is\na mixture of spiraling and bifurcations, primarily the former with small\nfriction and the latter with large friction. With zero friction, a simple model\npredicts that the maximum curvature and the total elastic energy scale as the\nwall radius to the -3/2 and -2 powers respectively. With nonzero friction, the\nelastic energy follows a similar scaling but with a prefactor up to 8 times\nlarger, due to delayering and bending with a range of small curvatures. For\nfriction coefficients as large as 1, the deformations are qualitatively similar\nwith and without friction at the outer wall. Above 1, the wall friction case\nbecomes dominated by buckling near the wall.",
        "positive": "An improved transform theory for estimation of number density\n  distribution of colloidal particles on a surface: A method for\n  colloidal-probe atomic force microscopy: In the short letter, we explain an improved transform theory for\ncolloidal-probe atomic force microscopy (CP-AFM). CP-AFM can measure a force\ncurve between the colloidal probe and a wall surface in a colloidal dispersion.\nThe transform theory can estimate the normalized number density distribution of\nthe colloidal particles on the wall from the force curve measured by CP-AFM.\nThe transform theory is important for study of the stratification of the\ncolloidal particles on the wall, which is related to fundamental studies of\ncolloidal crystal and glass."
    },
    {
        "anchor": "Generally applicable physics-based equation of state for liquids: Physics-based first-principles pressure-volume-temperature equations of state\n(EOS) exist for solids and gases but not for liquids due to the long-standing\nfundamental problems involved in liquid theory. Current EOS models that are\napplicable to liquids and supercritical fluids at liquid-like density under\nconditions relevant to planetary interiors and industrial processes are complex\nempirical models with many physically meaningless adjustable parameters. Here,\nwe develop a generally applicable physics-based (GAP) EOS for liquids including\nsupercritical fluids at liquid-like density. The GAP equation has only one\ndimensionless parameter: the Gr\\\"uneisen parameter for the fluid. The GAP\nequation is explicit in the internal energy, and hence links the most\nfundamental macroscopic static property of fluids, the\npressure-volume-temperature EOS, to their key microscopic property: the\nmolecular hopping frequency or liquid relaxation time, from which the internal\nenergy can be obtained. We test our GAP equation against available experimental\ndata in several different ways and find good agreement. We observe that the GAP\nequation is similar to the Mie-Gr\\\"{u}neisen solid EOS in a wide range of the\nliquid phase diagram. This similarity is ultimately related to the condensed\nstate of these two phases. On the other hand, the differences between the GAP\nequation and EOS for gases are fundamental. Finally, we identify the key gaps\nin the experimental data that need to be filled in to proceed further with the\nliquid EOS.",
        "positive": "Non-spherical nanoparticles in block copolymer composites: nanosquares,\n  nanorods and diamonds: A hybrid block copolymer(BCP) nanocomposite computational model is proposed\nto study nanoparticles(NPs) with a generalised shape including squares,\nrectangles and rhombus. Simulations are used to study the role of anisotropy in\nthe assembly of colloids within BCPs, ranging from NPs that are compatible with\none phase, to neutral NPs. The ordering of square-like NPs into grid\nconfigurations within a minority BCP domain was investigated, as well as the\nalignment of nanorods in a lamellar-forming BCP, comparing the simulation\nresults with experiments of mixtures of nanoplates and PS-\\textit{b}-PMMA BCP.\nThe assembly of rectangular NPs at the interface between domains resulted in\nalignment along the interface. The aspect ratio is found to play a key role on\nthe aggregation of colloids at the interface, which leads to a distinct\nco-assembly behaviour for low and high aspect ratio NPs."
    },
    {
        "anchor": "Kinetics of nanopore transport: A nonlinear kinetic exclusion model is used to study osmosis and pressure\ndriven flows through nearly single file pores such as antibiotic channels,\naquaporins, zeolites and nanotubules. Two possible maxima in the steady state\nflux as a function of pore-solvent affinity are found. For small driving\nforces, the linear macroscopic osmotic and hydraulic permeabilities $P_{os}$\nand $L_{p}$, are defined in terms of microscopic kinetic parameters. The\ndependences of the flux on activation energies, pore length and radius, and\ndriving forces are explored and Arrhenius temperature dependences derived.\nReasonable values for the physical parameters used in the analyses yield\ntransport rates consistent with experimental measurements. Experimental\nconsequences and interpretations are examined, and a straightforward extension\nto osmosis through disordered pores is given.",
        "positive": "Homogeneous Ice Nucleation Rate in Water Droplets: To predict the radiative forcing of clouds it is necessary to know the rate\nwith which ice homogeneously nucleates in supercooled water. Such rate is often\nmeasured in drops to avoid the presence of impurities. At large supercooling\nsmall (nanoscopic) drops must be used to prevent simultaneous nucleation\nevents. The pressure inside such drops is larger than the atmospheric one by\nvirtue of the Laplace equation. In this work, we take into account such\npressure raise in order to predict the nucleation rate in droplets using the\nTIP4P/Ice water model. We start from a recent estimate of the maximum drop size\nthat can be used at each supercooling avoiding simultaneous nucleation events\n[Espinosa et al. J. Chem. Phys., 2016]. We then evaluate the pressure inside\nthe drops with the Laplace equation. Finally, we obtain the rate as a function\nof the supercooling by interpolating our previous results for 1 and 2000 bar\n[Espinosa et al. Phys. Rev. Lett. 2016] using the Classical Nucleation Theory\nexpression for the rate. This requires, in turn, interpolating the ice-water\ninterfacial free energy and chemical potential difference. The TIP4P/Ice rate\ncurve thus obtained is in good agreement with most droplet-based experiments.\nIn particular, we find a good agreement with measurements performed using\nnanoscopic drops, that are currently under debate. The successful comparison\nbetween model and experiments suggests that TIP4P/Ice is a reliable model to\nstudy the water-to-ice transition and that Classical Nucleation Theory is a\ngood framework to understand it."
    },
    {
        "anchor": "First-principles molecular dynamics simulation of liquid indium: We report an ab-initio simulation of liquid Indium in a wide range of\npressures and temperatures. We calculate equation of state, thermal expansion\nand compressibility coefficients. The structure of the system is analyzed by\nradial distribution functions and structure factors. The results are compared\nwith available experimental data.",
        "positive": "Active particles using reinforcement learning to navigate in complex\n  motility landscapes: As the length scales of the smallest technology continue to advance beyond\nthe micron scale it becomes increasingly important to equip robotic components\nwith the means for intelligent and autonomous decision making with limited\ninformation. With the help of a tabular Q-learning algorithm, we design a model\nfor training a microswimmer, to navigate quickly through an environment given\nby various different scalar motility fields, while receiving a limited amount\nof local information. We compare the performances of the microswimmer, defined\nvia time of first passage to a target, with performances of suitable reference\ncases. We show that the strategy obtained with our reinforcement learning model\nindeed represents an efficient navigation strategy, that outperforms the\nreference cases. By confronting the swimmer with a variety of unfamiliar\nenvironments after the finalised training, we show that the obtained strategy\ngeneralises to different classes of random fields."
    },
    {
        "anchor": "Elasticity and onset of frictional dissipation at a non-sliding\n  multicontact interface: We measure the elastic and dissipative responses of a multicontact interface,\nformed between the rough surfaces of two contacting macroscopic solids,\nsubmitted to a biased oscillating shear force. We evidence that beyond a linear\nviscoelastic regime, observed at low shear amplitude, the interface response\nexhibits a dissipative component which corresponds to the onset of frictional\ndissipation. The latter regime exists whereas the tangential force applied, far\nfrom the nominal static threshold, does not provoke any sliding. This result,\nakin to that of Mindlin for a single contact, leads us to extend his model of\n`microslip' to the case of an interface composed of multiple microcontacts.\nWhile describing satisfactorily the elastic response, the model fails to\naccount quantitatively for the observed energy dissipation, which, we believe,\nresults from the fact that the key assumption of local Coulomb friction in\nMindlin's model is not legitimate at the sub-micrometer scale of the microslip\nzones within microcontacts between surface asperities.",
        "positive": "Theory of magnetoresistance based on variable-range hopping in the\n  presence of Hubbard interaction and spin-dynamics: We develop a theory of magnetoresistance based on variable-range hopping. An\nexponentially large, low-field and necessarily positive magnetoresistance\neffect is predicted in the presence of Hubbard interaction and spin-dynamics\nunder certain conditions. The theory was developed with the recently discovered\norganic magnetoresistance in mind. To account for the experimental observation\nthat the organic magnetoresistance effect can also be negative, we tentatively\namend the theory with a mechanism of bipolaron formation."
    },
    {
        "anchor": "Dynamically asymmetric and bicontinuous morphologies in active emulsions: The morphology of a mixture made of a polar active gel immersed in an\nisotropic passive fluid is studied numerically. Lattice Boltzmann method is\nadopted to solve the Navier-Stokes equation and coupled to a finite-difference\nscheme used to integrate the dynamic equations of the concentration and of the\npolarization of the active component. By varying the relative amounts of the\nmixture phases, different structures can be observed. In the contractile case,\nat moderate values of activity, elongated structures are formed when the active\ncomponent is less abundant, while a dynamic emulsion of passive droplets in an\nactive matrix is obtained for symmetric composition. When the active component\nis extensile, aster-like rotating droplets and a phase-separated pattern appear\nfor asymmetric and symmetric mixtures, respectively. The relevance of space\ndimensions in the overall morphology is shown by studying the system in three\ndimensions in the case of extensile asymmetric mixtures where interconnected\ntube-like structures span the whole system.",
        "positive": "Thermodynamic properties of a simple model of like-charged attracting\n  rods: We study the thermodynamic properties of a simple model for the possible\nmechanism of attraction between like charged rodlike polyions inside a\npolyelectrolyte solution. We consider two polyions in parallel planes, with $Z$\ncharges each, in a solution containing multivalent counterions of valence\n$\\alpha$. The model is solved exactly for $Z \\le 13$ for a general angle\n$\\theta$ between the rods and supposing that $n$ counterions are condensed on\neach polyion. The free energy has two minima, one at $\\theta=0$ (parallel rods)\nand another at $\\theta=\\pi/2$ (perpendicular rods). In general, in situations\nwhere an attractive force develops at small distances between the centers of\nthe polyions, the perpendicular configuration has the lowest free energy at\nlarge distances, while at small distances the parallel configuration minimizes\nthe free energy of the model. However, at low temperatures, a reentrant\nbehavior is observed, such that the perpendicular configuration is the global\nminimum for both large and small distances, while the parallel configuration\nminimizes the free energy at intermediate distances."
    },
    {
        "anchor": "Transport of free surface liquid films and drops by external ratchets\n  and self-ratcheting mechanisms: We discuss the usage of ratchet mechanisms to transport a continuous phase in\nseveral micro-fluidic settings. In particular, we study the transport of a\ndielectric liquid in a heterogeneous ratchet capacitor that is periodically\nswitched on and off. The second system consists of drops on a solid substrate\nthat are transported by different types of harmonic substrate vibrations. We\nargue that the latter can be seen as a self-ratcheting process and discuss\nanalogies between the employed class of thin film equations and Fokker-Planck\nequations for transport of discrete objects in a 'particle ratchet'.",
        "positive": "Polymer Nanofibers and Nanotubes: Charge Transport and Device\n  Applications: A critical analysis of recent advances in synthesis and electrical\ncharacterization of nanofibers and nanotubes made of different conjugated\npolymers is presented. The applicability of various theoretical models is\nconsidered in order to explain results on transport in conducting polymer\nnanofibers and nanotubes. The relationship between these results and the\none-dimensional (1D) nature of the conjugated polymers is discussed in light of\ntheories for tunneling in 1D conductors (e.g. Luttinger liquid, Wigner\ncrystal). The prospects for nanoelectronic applications of polymer fibers and\ntubes as wires, nanoscale field-effect transistors (nanoFETs), and in other\napplications are analyzed."
    },
    {
        "anchor": "Microstructural diversity, nucleation paths and phase behaviour in\n  binary mixtures of charged colloidal spheres: We study low-salt, binary aqueous suspensions of charged colloidal spheres of\nsize ratio Phi = 0.57, number densities below the eutectic number density n_E,\nand number fractions of p = 1.00-0.40. The typical phase obtained by\nsolidification from a homogeneous shear-melt is a substitutional alloy of body\ncentred cubic structure. In strictly gas-tight vials, the polycrystalline solid\nis stable against melting and further phase transformation for extended times.\nFor comparison, we prepare the same samples also by slow and mechanically\nundisturbed deionization in commercial slit cells. These cells feature a\ncomplex but well reproducible sequence of global and local gradients in salt\nconcentration, number density and composition as induced by successive\ndeionization, phoretic transport and differential settling of the components,\nrespectively. Moreover, they provide an extended bottom surface suitable for\nheterogeneous nucleation of the beta-phase. We give a detailed qualitative\ncharacterization of the crystallization processes using imaging and optical\nmicroscopy. By contrast to the bulk samples, the initial alloy formation in\nslit cells is not volume-filling, and we now observe also alpha- and\nbeta-phases with low solubility of the odd component. In addition to the\ninitial homogeneous nucleation route, the interplay of gradients opens various\nfurther crystallization and transformation pathways leading to a great\ndiversity of microstructures. Upon subsequent increase in salt concentration,\ncrystals melt again. Wall-based, pebble-shaped beta-phase crystals and facetted\nalpha-crystals melt last. Our observations suggest that the substitutional\nalloys formed in bulk experiments by homogeneous nucleation and subsequent\ngrowth are mechanically stable in the absence of solid-fluid interfaces but\nthermodynamically metastable.",
        "positive": "Abrasion of flat rotating shapes: We report on the erosion of flat linoleum \"pebbles\" under steady rotation in\na slurry of abrasive grit. To quantify shape as a function of time, we develop\na general method in which the pebble is photographed from multiple angles with\nrespect to the grid of pixels in a digital camera. This reduces digitization\nnoise, and allows the local curvature of the contour to be computed with a\ncontrollable degree of uncertainty. Several shape descriptors are then employed\nto follow the evolution of different initial shapes toward a circle, where\nabrasion halts. The results are in good quantitative agreement with a simple\nmodel, where we propose that points along the contour move radially inward in\nproportion to the product of the radius and the derivative of radius with\nrespect to angle."
    },
    {
        "anchor": "Ultra-stable shear jammed granular material: Dry granular materials such as sand, gravel, pills, or agricultural grains,\ncan become rigid when compressed or sheared. At low density, one can distort\nthe shape of a container of granular material without encountering any\nresistance. Under isotropic compression, the material will reach a certain {\\it\njamming} density and then resist further compression. {\\em Shear jamming}\noccurs when resistance to shear emerges in a system at a density lower than the\njamming density, and the elastic properties of such states have important\nimplications for industrial and geophysical processes. We report on\nexperimental observations of changes in the mechanical properties of a\nshear-jammed granular material subjected to small-amplitude, quasi-static\ncyclic shear. We study a layer of plastic discs confined to a shear cell, using\nphotoelasticimetry to measure all inter-particle vector forces. For\nsufficiently small cyclic shear amplitudes and large enough initial shear, the\nmaterial evolves to an unexpected \"ultra-stable\" state in which all the\nparticle positions and inter-particle contact forces remain unchanged after\neach complete shear cycle for thousands of cycles. The stress response of these\nstates to small imposed shear is nearly elastic, in contrast to the original\nshear jammed state.",
        "positive": "Theory of the dielectric susceptibility of liquid crystals with\n  bent-core molecules: Statistical theory of the dielectric susceptibility of polar liquid crystals\nis proposed. The molecules are calamitic or bent-core but the permanent dipole\nmoment is perpendicular to the molecule long axis. The ordering of the phase is\ndescribed by means of the mean-field theory based on the Maier-Saupe approach.\nThe theory is used to calculate the temperature dependence of the order\nparameters and the susceptibilities. The phase diagram with four phases is\nobtained: isotropic, uniaxial nematic, uniaxial ferroelectric, and biaxial\nferroelectric. Four critical points are predicted."
    },
    {
        "anchor": "Generalized hydrodynamics of the Lennard-Jones liquid in view of hidden\n  scale invariance: In recent years lines along which structure and dynamics are invariant to a\ngood approximation, so-called isomorphs, have been identified in the\nthermodynamic phase diagrams of several model liquids and solids. This paper\nreports computer simulations of the transverse and longitudinal collective\ndynamics at different length scales along an isomorph of the Lennard-Jones\nsystem. Our findings are compared to corresponding results along an isotherm\nand an isochore. Confirming the theoretical prediction, the reduced-unit\ndynamics of the transverse momentum density is invariant to a good\napproximation along the isomorph at all time and length scales. Likewise, the\nwave-vector dependent shear-stress autocorrelation function is found to be\nisomorph invariant. A similar invariance is not seen along the isotherm or the\nisochore. Using a spatially non-local hydrodynamic model for the transverse\nmomentum-density time-autocorrelation function, the macroscopic shear viscosity\nand its wave dependence are determined, demonstrating that the shear viscosity\nis isomorph invariant on all length scales studied. This analysis implies the\nexistence of a novel length scale which characterizes each isomorph. The\ntransverse sound-wave velocity, the Maxwell relaxation time, and the rigidity\nshear modulus are also isomorph invariant. In contrast, the reduced-unit\ndynamics of the mass density is not invariant at length scales longer than the\ninter-particle distance. By fitting to a generalized hydrodynamic model, we\nextract values for the wave-vector-dependent thermal diffusion coefficient,\nsound attenuation coefficient, and adiabatic sound velocity. The isomorph\nvariation of these quantities in reduced units at long length scales can be\neliminated by scaling with the density-scaling, a fundamental quantity in the\nisomorph theory framework, an empirical observation that remains to be\nexplained theoretically.",
        "positive": "Diffusion dynamics of star-shaped macromolecules in dilute solutions: Polymer chains dissolved in a solvent take random conformations due to large\ninternal degrees of freedom and are characterized geometrically by their\naverage shape and size. The diffusive dynamics of such large macromolecules\nplay an indispensable role in a plethora of engineering applications. The\ninfluence of the size of the polymer chain on its diffusion is well studied,\nwhereas the same cannot be said for the shape of the polymer chain. In the\npresent work, the influence of shape on the center-of-mass diffusion of the\nstar-shaped chains in solution is investigated using Multi-particle Collision\nDynamics. Star-shaped chains of varying degrees of functionality are modeled in\na good solvent at infinite dilution. The radius of gyration($R_g$) of the\nstar-shaped chains follows a functionality-independent scaling law with the\nchain length($N$), $R_g \\sim N^{\\nu}$, where $\\nu \\sim 0.627$. The shape of the\npolymer chains is calibrated by relative shape anisotropy. Highly anisotropic\nstar-shaped polymer chains are found to have a faster rate of diffusion along\nthe translational direction due to a slower rate of rotational diffusion when\nthe radius of gyration of the polymer chains is maintained constant."
    },
    {
        "anchor": "Fluid-driven deformation of a soft granular material: Compressing a porous, fluid-filled material will drive the interstitial fluid\nout of the pore space, as when squeezing water out of a kitchen sponge.\nInversely, injecting fluid into a porous material can deform the solid\nstructure, as when fracturing a shale for natural gas recovery. These\nporomechanical interactions play an important role in geological and biological\nsystems across a wide range of scales, from the propagation of magma through\nthe Earth's mantle to the transport of fluid through living cells and tissues.\nThe theory of poroelasticity has been largely successful in modeling\nporomechanical behavior in relatively simple systems, but this continuum theory\nis fundamentally limited by our understanding of the pore-scale interactions\nbetween the fluid and the solid, and these problems are notoriously difficult\nto study in a laboratory setting. Here, we present a high-resolution\nmeasurement of injection-driven poromechanical deformation in a system with\ngranular microsctructure: We inject fluid into a dense, confined monolayer of\nsoft particles and use particle tracking to reveal the dynamics of the\nmulti-scale deformation field. We find that a continuum model based on\nporoelasticity theory captures certain macroscopic features of the deformation,\nbut the particle-scale deformation field exhibits dramatic departures from\nsmooth, continuum behavior. We observe particle-scale rearrangement and\nhysteresis, as well as petal-like mesoscale structures that are connected to\nmaterial failure through spiral shear banding.",
        "positive": "Bose-Einstein condensation dynamics from the numerical solution of the\n  Gross-Pitaevskii equation: We study certain stationary and time-evolution problems of trapped\nBose-Einstein condensates using the numerical solution of the Gross-Pitaevskii\nequation with both spherical and axial symmetries. We consider time-evolution\nproblems initiated by changing the interatomic scattering length or harmonic\ntrapping potential suddenly in a stationary condensate. These changes introduce\noscillations in the condensate which are studied in detail. We use a time\niterative split-step method for the solution of the time-dependent\nGross-Pitaevskii equation, where all nonlinear and linear nonderivative terms\nare treated separately from the time propagation with the kinetic energy terms.\nEven for an arbitrarily strong nonlinear term this leads to extremely accurate\nand stable results after millions of time iterations of the original equation."
    },
    {
        "anchor": "A Kirchhoff-like theory for hard magnetic rods under geometrically\n  nonlinear deformation in three dimensions: Magneto-rheological elastomers (MREs) are functional materials that can be\nactuated by applying an external magnetic field. MREs comprise a composite of\nhard magnetic particles dispersed into a nonmagnetic elastomeric matrix. By\napplying a strong magnetic field, one can magnetize the structure to program\nits deformation under the subsequent application of an external field. Hard\nMREs, whose coercivities are large, have been receiving particular attention\nbecause the programmed magnetization remains unchanged upon actuation. Hence,\nonce a structure made of a hard MRE is magnetized, it can be regarded as\nmagnetized permanently. Motivated by a new realm of applications, there have\nbeen significant theoretical developments in the continuum description of hard\nMREs. By reducing the 3D description into 1D or 2D via dimensional reduction,\nseveral theories of hard magnetic slender structures such as linear beams,\nelastica, and shells have been recently proposed. In this paper, we derive an\neffective theory for MRE rods under geometrically nonlinear 3D deformation. Our\ntheory is based on reducing the 3D magneto-elastic energy functional for the\nhard MREs into a 1D Kirchhoff-like description. Restricting the theory to 2D,\nwe reproduce previous works on planar deformations. For further validation in\nthe general case of 3D deformation, we perform precision experiments with both\nnaturally straight and curved rods under either constant or constant-gradient\nmagnetic fields. Our theoretical predictions are in excellent agreement with\nboth discrete simulations and precision-model experiments. Finally, we discuss\nsome limitations of our framework, as highlighted by the experiments, where\nlong-range dipole interactions, which are neglected in the theory, can play a\nrole.",
        "positive": "Gel Formation in Reversibly Cross-Linking Polymers: By means of Langevin dynamics simulations, we investigate the gel formation\nof randomly functionalized polymers in solution, with the ability to form both\nintra- and intermolecular reversible bonds. Under highly dilute conditions,\nthese polymers form soft nano-objects (so-called single-chain nanoparticles,\nSCNPs), resulting from the purely intramolecular cross-linking of the reactive\nfunctional groups. Here we show that the competition between intra- and\nintermolecular bonds at finite concentration is governed by a delicate balance\nof various entropic contributions and leads to a density dependent effective\nvalence. System-spanning networks are formed at relatively low monomer\ndensities and their stability is mediated by just a small number of\nintermolecular connections per chain. The formation of intermolecular bonds\nfurthermore can induce a non-monotonic dependence of the polymer size on the\ndensity for long bond lifetimes. Concomitantly, the polymers in the percolating\ncluster adopt an intramolecular structure characteristic for self-avoiding\nchains, which constitutes a strong contrast to the fractal globular behavior of\nirreversible SCNPs in crowded solutions with purely topological interactions\n(no intermolecular bonds). Finally, we study the dynamics of the system, which\ndisplays signatures expected for reversible gel-forming systems. An interesting\nbehavior emerges in the reorganization dynamics of the percolating cluster. The\nrelaxation is mostly mediated by the diffusion over long distances, through\nbreaking and formation of bonds, of chains that do not leave the percolating\ncluster. Regarding the few chains that are transiently free, the time they\nspend until they reattach to the cluster is solely governed by the bond\nstrength."
    },
    {
        "anchor": "Role of viscoelasticity on the dynamics and aggregation of chemically\n  active sphere-dimers: The impact of complex media on the dynamics of active swimmers has gained a\nthriving interest in the research community for their prominent applications in\nvarious fields. This paper investigates the effect of viscoelasticity on the\ndynamics and aggregation of chemically powered sphere-dimers by using a\ncoarse-grained hybrid mesoscopic simulation technique. The sphere-dimers\nperform active motion by virtue of the concentration gradient around the\nswimmer's surface, produced by the chemical reaction at one end of the dimer.\nWe observe that the fluid elasticity enhances translational and rotational\nmotion of a single dimer, however for a pair of dimers, the clustering in a\nparticular alignment is more pronounced. In case of multiple dimers, the\nkinetics of cluster formation along with their propulsive nature are presented\nin detail. The key factors influencing the enhanced motility and the\naggregation of dimers are the concentration gradients, hydrodynamic coupling\nand the microstructures present in the system.",
        "positive": "A connection between Living Liquid Crystals and electrokinetic phenomena\n  in nematic fluids: We develop a formal analogy between configurational stresses in two distinct\nphysical systems, and study the flows that they induce when the configurations\nof interest include topological de- fects. The two systems in question are\nelectrokinetic flows in a nematic fluid under an applied electrostatic field,\nand the motion of self propelling or active particles in a nematic matrix (a\nliving liquid crystal). The mapping allows the extension, within certain\nlimits, of existing results on trans- port in electrokinetic systems to self\npropelled transport. We study motion induced by a pair of point defects in a\ndipole configuration, and steady rotating flows due to a swirling vortex\nnematic director pattern. The connection presented allows the design of\nelectrokinetic experiments that correspond to particular active matter\nconfigurations that may, however, be easier to conduct and control in the\nlaboratory."
    },
    {
        "anchor": "M13-phage-based star-shaped particles with internal flexibility: We report on the construction and the dynamics of monodisperse star-shaped\nparticles, mimicking, at the mesoscale, star polymers. Such multi-arm star-like\nparticles result from the self-assembly of gold nanoparticles, forming the\ncore, with tip-linked filamentous viruses - M13 bacteriophages - acting as\nspines in a sea urchin-like structure. By combining fluorescence and dark-field\nmicroscopy with dynamic light scattering, we investigate the diffusion of these\nhybrid spiny particles. We reveal the internal dynamics of the star particles\nby probing their central metallic core, which exhibits a hindered motion that\ncan be described as a Brownian particle trapped in a harmonic potential. We\ntherefore show that the filamentous viruses and specifically their tip proteins\nbehave as entropic springs, extending the relevance of the study of such hybrid\nmesoscopic analogs of star polymers to phage biotechnology.",
        "positive": "On the universality class of the special adsorption point of\n  two-dimensional lattice polymers: In recent work [PRE 100, 022121 (2019)] evidence was found that the surface\nadsorption transition of interacting self-avoiding trails (ISATs) placed on the\nsquare lattice displays a non-universal behavior at the special adsorption\npoint (SAP) where the collapsing polymers adsorb. In fact, different surface\nexponents $\\phi^{(s)}$ and $1/\\delta^{(s)}$ were found at the SAP depending on\nwhether the surface orientation is horizontal (HS) or diagonal (DS). Here, we\nrevisit these systems and study other ones, through extensive Monte Carlo\nsimulations, considering much longer trails than previous works. Importantly,\nwe demonstrate that the different exponents observed in the reference above are\ndue to the presence of a previously unseen surface-attached-globule (SAG) phase\nin the DS system, which changes the multicritical nature of the SAP and is\nabsent in the HS case. By considering a modified horizontal surface (mHS) where\nthe trails are forbidden of having two consecutive steps along it, resembling\nthe DS situation, a stable SAG phase is found in the phase diagram, and both DS\nand mHS systems present similar $1/\\delta^{(s)}$ exponents at the SAP, being\n$1/\\delta^{(s)} \\approx 0.44$, whilst $1/\\delta^{(s)} \\approx 0.34$ in the HS\ncase. Intriguingly, while $\\phi^{(s)} \\approx 1/\\delta^{(s)}$ is found for the\nDS and HS scenarios, as expected, in the mHS case $\\phi^{(s)}$ is about $10$\\%\nsmaller than $1/\\delta^{(s)}$. These results strongly indicate that at least\ntwo universality classes exist for the SAPs of adsorbing ISATs on the square\nlattice."
    },
    {
        "anchor": "Propulsion with a Rotating Elastic Nanorod: The dynamics of a rotating elastic filament is investigated using Stokesian\nsimulations. The filament, straight and tilted with respect to its rotation\naxis for small driving torques, undergoes at a critical torque a strongly\ndiscontinuous shape bifurcation to a helical state. It induces a substantial\nforward propulsion whatever the sense of rotation: a nanomechanical\nforce-rectification device is established.",
        "positive": "Determination of Young's modulus of active pharmaceutical ingredients by\n  relaxation dynamics at elevated pressures: A new approach is theoretically proposed to study the glass transition of\nactive pharmaceutical ingredients and a glass-forming anisotropic molecular\nliquid at high pressures. We describe amorphous materials as a fluid of hard\nspheres. Effects of nearest-neighbor interactions and cooperative motions of\nparticles on glassy dynamics are quantified through a local and collective\nelastic barrier calculated using the Elastically Collective Nonlinear Langevin\nEquation theory. Inserting two barriers into Kramer's theory gives structural\nrelaxation time. Then, we formulate a new mapping based on the thermal\nexpansion process under pressure to intercorrelate particle density,\ntemperature, and pressure. This analysis allows us to determine the pressure\nand temperature dependence of alpha relaxation. From this, we estimate an\neffective elastic modulus of amorphous materials and capture effects of\nconformation on the relaxation process. Remarkably, our theoretical results\nagree well with experiments."
    },
    {
        "anchor": "Comparison of splashing in high and low viscosity liquids: We explore the evolution of a splash when a liquid drop impacts a smooth, dry\nsurface. There are two splashing regimes that occur when the liquid viscosity\nis varied, as is evidenced by its dependence on ambient gas pressure. A\nhigh-viscosity drop splashes by emitting a thin sheet of liquid from a\nspreading liquid lamella long after the drop has first contacted the solid.\nLikewise, we find that there is also a delay in the ejection of a thin sheet\nwhen a low-viscosity drop splashes. We show how the ejection time of the thin\nsheet depends on liquid viscosity and ambient gas pressure.",
        "positive": "Dielectric effects in the self-assembly of binary colloidal aggregates: Electrostatic interactions play an important role in numerous self-assembly\nphenomena, including colloidal aggregation. Although colloids typically have a\ndielectric constant that differs from the surrounding solvent, the effective\ninteractions that arise from inhomogeneous polarization charge distributions\nare generally neglected in theoretical and computational studies. We introduce\nan efficient technique to resolve polarization charges in dynamical dielectric\ngeometries, and demonstrate that dielectric effects \\emph{qualitatively} alter\nthe predicted self-assembled structures, with surprising colloidal strings\narising from many-body effects."
    },
    {
        "anchor": "Universal Kinetics of the Sol-to-Gel Transition: A comprehensive theory encompassing the kinetics of sol-to-gel transition is\nyet to be formulated due to break-down of the mean-field Smoluchowski Equation.\nUsing high temporal-resolution Monte Carlo simulation of irreversible\naggregation systems, we show that this transition has three distinct regimes\nwith kinetic exponent z ranging between 1 and 2, corresponding to aggregation\nof sol clusters proceeding to the ideal gel point (IGP); z ranging between 2\nand 5.7 for gelation of sol clusters beyond IGP; and z ranging between 2 and\n3.5 for a hitherto unidentified regime involving aggregation of gels when\nmonomer-dense. We further establish universal power-law scaling relationships\nthat connect the kinetics of these three regimes.",
        "positive": "Tank-treading as a means of propulsion in viscous shear flows: The use of tank-treading as a means of propulsion for microswimmers in\nviscous shear flows is taken into exam. We discuss the possibility that a\nvesicle be able to control the drift in an external shear flow, by varying\nlocally the bending rigidity of its own membrane. By analytical calculation in\nthe quasi-spherical limit, the stationary shape and the orientation of the\ntank-treading vesicle in the external flow, are determined, working to lowest\norder in the membrane inhomogeneity. The membrane inhomogeneity acts in the\nshape evolution equation as an additional force term, that can be used to\nbalance the effect of the hydrodynamic stresses, thus allowing the vesicle to\nassume shapes and orientations that would otherwise be forbidden. The vesicle\nshapes and orientations required for migration transverse to the flow, together\nwith the bending rigidity profiles that would lead to such shapes and\norientations, are determined. A simple model is presented, in which a vesicle\nis able to migrate up or down the gradient of a concentration field, by\nstiffening or softening of its membrane, in response to the variations in the\nconcentration level experienced during tank-treading."
    },
    {
        "anchor": "Scaling and Universality in the Counterion-Condensation Transition at\n  Charged Cylinders: We address the critical and universal aspects of counterion-condensation\ntransition at a single charged cylinder in both two and three spatial\ndimensions using numerical and analytical methods. By introducing a novel\nMonte-Carlo sampling method in logarithmic radial scale, we are able to\nnumerically simulate the critical limit of infinite system size (corresponding\nto infinite-dilution limit) within tractable equilibration times. The critical\nexponents are determined for the inverse moments of the counterionic density\nprofile (which play the role of the order parameters and represent the inverse\nlocalization length of counterions) both within mean-field theory and within\nMonte-Carlo simulations. In three dimensions (3D), correlation effects\n(neglected within mean-field theory) lead to an excessive accumulation of\ncounterions near the charged cylinder below the critical temperature\n(condensation phase), while surprisingly, the critical region exhibits\nuniversal critical exponents in accord with the mean-field theory. In two\ndimensions (2D), we demonstrate, using both numerical and analytical\napproaches, that the mean-field theory becomes exact at all temperatures\n(Manning parameters), when number of counterions tends to infinity. For finite\nparticle number, however, the 2D problem displays a series of peculiar singular\npoints (with diverging heat capacity), which reflect successive de-localization\nevents of individual counterions from the central cylinder. In both 2D and 3D,\nthe heat capacity shows a universal jump at the critical point, and the energy\ndevelops a pronounced peak. The asymptotic behavior of the energy peak location\nis used to locate the critical temperature, which is also found to be universal\nand in accordance with the mean-field prediction.",
        "positive": "Elasto-capillarity at the nanoscale: on the coupling between elasticity\n  and surface energy in soft solids: The capillary forces exerted by liquid drops and bubbles on a soft solid are\ndirectly measured using molecular dynamics simulations. The force on the solid\nby the liquid near the contact line is not oriented along the liquid vapor\ninterface nor perpendicular to the solid surface, as usually assumed, but\npoints towards the liquid.\n  It is shown that the elastic deformations induced by this force can only be\nexplained if, contrary to an incompressible liquid, the surface stress is\ndifferent from the surface energy. Using thermodynamic variations we show that\nthe the surface stress and the surface energy can both be determined accurately\nby measuring the deformation of a slender body plunged in a liquid. The results\nobtained from molecular dynamics fully confirm those recently obtained\nexperimentally [Marchand et al. Phys. Rev. Lett. 108, 094301 (2012)] for an\nelastomeric wire."
    },
    {
        "anchor": "The low temperature interface between the gas and solid phases of hard\n  spheres with a short-ranged attraction: At low temperature, spheres with a very short-ranged attraction exist as a\nclose-packed solid coexisting with an infinitely dilute gas. We find that the\nratio of the interfacial tension between these two phases to the thermal energy\ndiverges as the range of the attraction goes to zero. The large tensions when\nthe interparticle attractions are short-ranged may be why globular proteins\nonly crystallise over a narrow range of conditions.",
        "positive": "Comprehensive Analysis of Dewetting Profiles to Quantify Hydrodynamic\n  Slip: Hydrodynamic slip of Newtonian liquids is a new phenomenon, the origin of\nwhich is not yet clarified. There are various direct and indirect techniques to\nmeasure slippage. Here we describe a method to characterize the influence of\nslippage on the shape of rims surrounding growing holes in thin polymer films.\nAtomic force microscopy is used to study the shape of the rim; by analyzing its\nprofile and applying an appropriate lubrication model we are able to determine\nthe slip length for polystyrene films. In the experiments we study polymer\nfilms below the entanglement length that dewet from hydrophobized (silanized)\nsurfaces. We show that the slip length at the solid/liquid interface increases\nwith increasing viscosity. The correlation between viscosity and slip length is\ndependent on the type of silanization. This indicates a link between the\nmolecular mechanism of the interaction of polymer chains and silane molecules\nunder flow conditions that we will discuss in detail."
    },
    {
        "anchor": "Electrostatics-driven shape transitions in soft shells: Manipulating the shape of nanoscale objects in a controllable fashion is at\nthe heart of designing materials that act as building blocks for self-assembly\nor serve as targeted drug delivery carriers. Inducing shape deformations by\ncontrolling external parameters is also an important way of designing\nbiomimetic membranes. In this paper, we demonstrate that electrostatics can be\nused as a tool to manipulate the shape of soft, closed membranes by tuning\nenvironmental conditions such as the electrolyte concentration in the medium.\nUsing a molecular dynamics-based simulated annealing procedure, we investigate\ncharged elastic shells that do not exchange material with their environment,\nsuch as elastic membranes formed in emulsions or synthetic nanocontainers. We\nfind that by decreasing the salt concentration or increasing the total charge\non the shell's surface, the spherical symmetry is broken, leading to the\nformation of ellipsoids, discs, and bowls. Shape changes are accompanied by a\nsignificant lowering of the electrostatic energy and a rise in the surface area\nof the shell. To substantiate our simulation findings, we show analytically\nthat a uniformly charged disc has a lower Coulomb energy than a sphere of the\nsame volume. Further, we test the robustness of our results by including the\neffects of charge renormalization in the analysis of the shape transitions and\nfind the latter to be feasible for a wide range of shell volume fractions.",
        "positive": "Interfacial free energy and Tolman length of curved liquid-solid\n  interfaces from equilibrium studies: In this work, we study by means of simulations of hard spheres the\nequilibrium between a spherical solid cluster and the fluid. In the NVT\nensemble we observe stable/metastable clusters of the solid phase in\nequilibrium with the fluid, representing configurations that are global/local\nminima of the Helmholtz free energy. Then, we run NpT simulations of the\nequilibrated system at the average pressure of the NVT run and observe that the\nclusters are critical because they grow/shrink with a probability of 1/2.\nTherefore, a crystal cluster equilibrated in the NVT ensemble corresponds to a\nGibbs free energy maximum where the nucleus is in unstable equilibrium with the\nsurrounding fluid, in accordance with what has been recently shown for vapor\nbubbles in equilibrium with the liquid. Then, within the Seeding framework, we\nuse Classical Nucleation Theory to obtain both the interfacial free energy\n{\\gamma} and the nucleation rate. The latter is in very good agreement with\nindependent estimates using techniques that do not rely on Classical Nucleation\nTheory when the mislabeling criterion is used to identify the molecules of the\nsolid cluster. We therefore argue that the radius obtained from the mislabeling\ncriterion provides a good approximation for the radius of tension, Rs. We\nobtain an estimate of the Tolman length by extrapolating the difference between\nRe (the Gibbs dividing surface) and Rs to infinite radius. We show that such\ndefinition of the Tolman length coincides with that obtained by fitting\n{\\gamma} versus 1/Rs to a straight line as recently applied to hard spheres\n[Montero de Hijes et al., J. Chem. Phys. 151, 155401, 2019]"
    },
    {
        "anchor": "FFT-LB modeling of thermal liquid-vapor systems: We further develop a thermal LB model for multiphase flows. In the improved\nmodel, we propose to use the FFT scheme to calculate both the convection term\nand external force term. The usage of FFT scheme is detailed and analyzed. By\nusing the FFT algorithm spatiotemporal discretization errors are decreased\ndramatically and the conservation of total energy is much better preserved. A\ndirect consequence of the improvement is that the unphysical spurious\nvelocities at the interfacial regions can be damped to neglectable scale.\nTogether with the better conservation of total energy, the more accurate flow\nvelocities lead to the more accurate temperature field which determines the\ndynamical and final states of the system. With the new model, the phase diagram\nof the liquid-vapor system obtained from simulation is more consistent with\nthat from theoretical calculation. Very sharp interfaces can be achieved. The\naccuracy of simulation results are also verified by the Laplace law. The FFT\nscheme can be easily applied to other models for multiphase flows.",
        "positive": "Local Dielectric Spectroscopy of Nanocomposite Materials Interfaces: Local dielectric spectroscopy is performed to study how relaxation dynamics\nof a poly-vinyl-acetate ultra-thin film is influenced by inorganic\nnano-inclusions of a layered silicate (montmorillonite). Dielectric loss\nspectra are measured by electrostatic force microscopy in the\nfrequency-modulation mode in ambient air. Spectral changes in both shape and\nrelaxation time are evidenced across the boundary between pure polymer and\nmontmorillonite sheets. Dielectric loss imaging is also performed, evidencing\nspatial variations of dielectric properties near to nanostructures with\nnanometer scale resolution."
    },
    {
        "anchor": "Surface extrapolation length and director structures in confined\n  nematics: We report the results of Monte Carlo simulations of the Lebwohl--Lasher model\nof nematic liquid crystals confined to cylindrical cavities with homeotropic\nanchoring. We show that the ratio of the bulk to surface couplings is not in\ngeneral equal to the corresponding parameter K/W used in elastic theory (where\nK is the Frank elastic constant in the one constant approximation and W is the\nsurface anchoring strength). By measuring the temperature dependence of K/W\n(which is equivalent to the surface extrapolation length) we are able to\nreconcile the results of our simulations as well as others with the predictions\nof elastic theory. We find that the rate at which we cool the system from the\nisotropic to nematic phase plays a crucial role in the development of the final\ndirector structure, because of a large free energy barrier separating different\ndirector structures as well as the temperature dependence of $K/W$. With a\nsuitably fast cooling rate we are able to keep the system out of a metastable\nplanar state and form an escaped radial structure for large enough systems.",
        "positive": "Thermoelastic-Plastic Flow Equations in General Coordinates: The equations governing the thermoelastic-plastic flow of isotropic solids in\nthe Prandtl-Reuss and small anisotropy approximations in Cartesian coordinates\nare generalized to arbitrary coordinate systems. In applications the choice of\ncoordinates is dictated by the symmetry of the solid flow. The generally\ninvariant equations are evaluated in spherical, cylindrical (including\nuniaxial), and both prolate and oblate spheroidal coordinates."
    },
    {
        "anchor": "Topology mediated organization of E.coli chromosome in fast growth\n  conditions: Recent experiments have been able to visualise chromosome organization in\nfast-growing E.coli cells. However, the mechanism underlying the\nspatio-temporal organization remains poorly understood. We propose that the DNA\nadopts a specific polymer topology as it goes through its cell cycle. We\nestablish that the emergent entropic forces between polymer segments of the\nDNA-polymer with modified topology, leads to chromosome organization as seen\nin-vivo. We employ computer simulations of a replicating bead spring model of a\npolymer in a cylinder to investigate the problem. Our simulation of the\noverlapping cell cycles not only show successful segregation, but also\nreproduces the evolution of the spatial organization of the chromosomes as\nobserved in experiments. This manuscript in addition to our previous work on\nslowly growing bacterial cells, shows that our topology-based model can explain\nthe organization of chromosomes in all growth conditions.",
        "positive": "Programmed Wrapping and Assembly of Droplets with Mesoscale Polymers: Nature is remarkably adept at using interfaces to build structures,\nencapsulate reagents, and regulate biological processes. Inspired by Nature, we\ndescribe flexible polymer-based ribbons, termed \"mesoscale polymers\" (MSPs), to\nmodulate interfacial interactions with liquid droplets. This produces\nunprecedented hybrid assemblies in the forms of flagellum-like structures and\nMSP-wrapped droplets. Successful preparation of these hybrid structures hinges\non interfacial interactions and tailored MSP compositions, such as MSPs with\ndomains possessing distinctly different affinity for fluid-fluid interfaces as\nwell as mechanical properties. In situ measurements of MSP-droplet interactions\nconfirm that MSPs possess a negligible bending stiffness, allowing interfacial\nenergy to drive mesoscale assembly. By exploiting these interfacial driving\nforces, mesoscale polymers are demonstrated as a powerful platform that\nunderpins the preparation of sophisticated hybrid structures in fluids."
    },
    {
        "anchor": "Dynamics of Hard Colloidal Cuboids in Nematic Liquid Crystals: We perform Dynamic Monte Carlo simulations to investigate the equilibrium\ndynamics of hard colloidal cuboids in oblate and prolate nematic liquid\ncrystals. In particular, we characterise the particles' diffusion along the\nnematic director and perpendicularly to it, and observe a structural relaxation\ndecay that strongly depend on the particle anisotropy. To assess the\nGaussianity of their dynamics and eventual occurrence of collective motion, we\ncalculate two- and four-point correlation functions that incorporate the\ninstantaneous values of the diffusion coefficients parallel and perpendicular\nto the nematic director. Our simulation results highlight the occurrence of\nFickian and Gaussian dynamics at short and long times, locate the minimum\ndiffusivity at the self-dual shape, the particle geometry that would\npreferentially stabilise biaxial nematics, and exclude the existence of\ndynamically correlated particles.",
        "positive": "Erosion dynamics of a wet granular medium: Liquid may give strong cohesion properties to a granular medium, and confer a\nsolid-like behavior. We study the erosion of a fixed circular aggregate of wet\ngranular matter subjected to a flow of dry grains inside a half-filled rotating\ndrum. During the rotation, the dry grains flow around the fixed obstacle. We\nshow that its diameter decreases linearly with time for low liquid content, as\nwet grains are pulled-out of the aggregate. This erosion phenomenon is governed\nby the properties of the liquids. The erosion rate decreases exponentially with\nthe surface tension while it depends on the viscosity to the power -1. We\npropose a model based on the force fluctuations arising inside the flow,\nexplaining both dependencies: the capillary force acts as a threshold and the\nviscosity controls the erosion time scale. We also provide experiments using\ndifferent flowing grains confirming our model."
    },
    {
        "anchor": "Equilibrium clusters in suspensions of colloids interacting via\n  potentials with a local minimum: In simple colloidal suspensions, clusters are various multimers that result\nfrom colloid self-association and exist in equilibrium with monomers.There are\ntwo types of potentials that are known to produce clusters: a) potentials that\nresult from the competition between short-range attraction and long-range\nrepulsion and are characterized by a global minimum and a repulsive tail and b)\npurely repulsive potentials which have a soft shoulder. Using computer\nsimulations, we demonstrate in this work that potentials with a local minimum\nand a repulsive tail, not belonging to either of the known types, are also\ncapable of generating clusters. A detailed comparative analysis shows that the\nnew type of cluster-forming potential serves as a bridge between the other two.\nThe new clusters are expanded in shape and their assembly is driven by entropy,\nlike in the purely repulsive systems but only at low density. At high density,\nclusters are collapsed and stabilized by energy, in common with the systems\nwith competing attractive and repulsive interactions.",
        "positive": "Strain Stiffening Induced by Molecular Motors in Active Crosslinked\n  Biopolymer Networks: We have studied the elastic response of actin networks with both compliant\nand rigid crosslinks by modeling molecular motors as force dipoles. Our finite\nelement simulations show that for compliant crosslinkers such as filamin A, the\nnetwork can be stiffened by two orders of magnitude while stiffening achieved\nwith incompliant linkers such as scruin is significantly smaller, typically a\nfactor of two, in excellent agreement with recent experiments. We show that the\ndifferences arise from the fact that the motors are able to stretch the\ncompliant crosslinks to the fullest possible extent, which in turn causes to\nthe deformation of the filaments. With increasing applied strain, the filaments\nfurther deform leading to a stiffened elastic response. When the crosslinks are\nincompliant, the contractile forces due to motors do not alter the network\nmorphology in a significant manner and hence only small stiffening is observed."
    },
    {
        "anchor": "Structural changes across thermodynamic maxima in supercooled liquid\n  tellurium: a water-like scenario: Liquid polymorphism is an intriguing phenomenon which has been found in a few\nsingle-component systems, the most famous being water. By supercooling liquid\nTe to more than 130 K below its melting point and performing simultaneous\nsmall-angle and wide-angle X-ray scattering measurements, we observe clear\nmaxima in its thermodynamic response functions around 615 K, suggesting the\npossible existence of liquid polymorphism. A close look at the underlying\nstructural evolution shows the development of intermediate-range order upon\ncooling, most strongly around the thermodynamic maxima, which we attribute to\nbond-orientational ordering. The striking similarities between our results and\nthose of water, despite the lack of hydrogen-bonding and tetrahedrality in\ntellurium, indicate that water-like anomalies may be a general phenomenon among\nliquid systems with competing bond- and density-ordering.",
        "positive": "Overload wave-memory induces amnesia of a self-propelled particle: Information storage is a key element of autonomous, out-of-equilibrium\ndynamics, especially for biological and synthetic active matter. In synthetic\nactive matter however, the implementation of internal memory in self-propelled\nsystems is often absent, limiting our understanding of memory-driven dynamics.\nRecently, a system comprised of a droplet generating its guiding wavefield\nappeared as a prime candidate for such investigations. Indeed, the wavefield,\npropelling the droplet, encodes information about the droplet trajectory and\nthe amount of information can be controlled by a single scalar experimental\nparameter. In this work, we show numerically and experimentally that the\naccumulation of information in the wavefield induces the loss of time\ncorrelations, where the dynamics can then be described by a memory-less\nprocess. We rationalize the resulting statistical behaviour by defining an\neffective temperature for the particle dynamics where the wavefield acts as a\nthermostat of large dimensions, and by evidencing a minimization principle of\nthe generated wavefield."
    },
    {
        "anchor": "Many-body dipole-induced dipole model for electrorheological fluids: Theoretical investigations on electrorheological (ER) fluids usually rely on\ncomputer simulations. An initial approach for these studies would be the\npoint-dipole (PD) approximation, which is known to err considerably when the\nparticles approach and finally touch due to many-body and multipolar\ninteractions. Thus various work attempted to go beyond the PD model. Being\nbeyond the PD model, previous attempts have been restricted to either\nlocal-field effects only or multipolar effects only, but not both. For\ninstance, we recently proposed a dipole-induced-dipole (DID) model which is\nshown to be both more accurate than the PD model and easy to use. This work is\nnecessary because the many-body (local-field) effect is included to put forth\nthe many-body DID model. The results show that the multipolar interactions can\nindeed be dominant over the dipole interaction, while the local-field effect\nmay yield an important correction.",
        "positive": "Correlating thermodynamics, morphology, mechanics and thermal transport\n  in PMMA-PLA blends: Thermodynamics controls structure, function, stability and morphology of\npolymer blends. However, obtaining the precise information about their mixing\nthermodynamics is a challenging task, especially when dealing with complex\nmacromolecules. This is partially because of a delicate balance between the\nlocal concentration/composition fluctuations and the monomer level (multi-body)\ninteractions. In this context, the Kirkwood-Buff (KB) theory serves as a useful\ntool that connects the local pairwise fluid structure to the mixing\nthermodynamics. Using larger scale molecular dynamics simulations, within the\nframework of KB theory, we investigate a set of technologically relevant\npoly(methyl methacrylate)-poly(lactic acid) (PMMA-PLA) blends with the aim to\nelucidate the underlying microscopic picture of their phase behavior.\nConsistent with these experiments, we emphasize the importance of properly\naccounting for the entropic contribution, to the mixing Gibbs free energy\nchange $\\Delta {\\mathcal G}_{\\rm mix}$, that controls the phase morphology. We\nfurther show how the relative microscopic interaction details and the molecular\nlevel structures between different mixing species can control the non-linear\nmechanics and ductility. As a direct consequence, we provide a correlation that\nlinks thermodynamics, phase behavior, mechanics, and thus also thermal\ntransport in polymer blends. Therefore, this study provides a guiding principle\nfor the design of light weight functional materials with extraordinary physical\nproperties."
    },
    {
        "anchor": "Defect-free Perpendicular Diblock Copolymer Films: The Synergistic\n  Effect of Surface Topography and Chemistry: We propose a direct self-assembly mechanism towards obtaining defect-free\nperpendicular lamellar phases of diblock copolymer (BCP) thin films. In our\nnumerical study, a thin BCP film having a flat top surface is casted on a\nuni-directional corrugated solid substrate. The substrate is treated chemically\nand has a weak preference toward one of the two BCP components. Employing\nself-consistent field theory (SCFT), we find that there is an enhanced synergy\nbetween two substrate characteristics: its topography (geometrical roughness)\ncombined with a weak surface preference. This synergy produces the desired\nperpendicular lamellar phase with perfect inplane ordering. Defect-free BCP\nlamellar phases are reproducible for several random initial states, and are\nobtained for a range of substrate roughness and chemical characteristics, even\nfor a uni-directional multi-mode substrate roughness. Our theoretical study\nsuggests possible experiments that will explore the interplay between\nuni-directional substrate corrugation and chemical surface treatment. It may\nlead to viable and economical ways of obtaining BCP films with defect-free\nlateral alignment.",
        "positive": "Thermal phase diagrams of columnar liquid crystals: In order to understand the possible sequence of transitions from the\ndisordered columnar phase to the helical phase in hexa(hexylthio)triphenylene\n(HHTT), we study a three-dimensional planar model with octupolar interactions\ninscribed on a triangular lattice of columns. We obtain thermal phase diagrams\nusing a mean-field approximation and Monte Carlo simulations. These two\napproaches give similar results, namely, in the quasi one-dimensional regime,\nas the temperature is lowered, the columns order with a linear polarization,\nwhereas helical phases develop at lower temperatures. The helicity patterns of\nthe helical phases are determined by the exact nature of the frustration in the\nsystem, itself related to the octupolar nature of the molecules."
    },
    {
        "anchor": "Conformational transformations induced by the charge-curvature\n  interaction: A simple phenomenological model for describing the conformational dynamics of\nbiological macromolecules via the nonlinearity-induced instabilities is\nproposed. It is shown that the interaction between charges and bending degrees\nof freedom of closed molecular aggregates may act as drivers giving impetus to\nconformational dynamics of biopolymers. It is demonstrated that initially\ncircular aggregates may undergo transformation to polygonal shapes and possible\napplication to aggregates of bacteriochlorophyl a molecules is considered.",
        "positive": "Theory for the single-particle dynamics in glassy mixtures with particle\n  size swaps: We present a theory for the single-particle dynamics in binary mixtures with\nparticle size swaps. The general structure of the theory follows that of the\ntheory for the collective dynamics in binary mixtures with particle size swaps,\nwhich we developed previously [G. Szamel, Phys. Rev. E 98, 050601(R) (2018)].\nParticle size swaps open up an additional relaxation channel, which speeds up\nboth the collective dynamics and the single-particle dynamics. To make explicit\npredictions, we resort to a factorization approximation similar to that\nemployed in the mode-coupling theory of glassy dynamics. We show that, like in\nthe standard mode-coupling theory, the single-particle motion becomes arrested\nat the dynamic glass transition predicted by the theory for the collective\ndynamics. We compare the non-ergodicity parameters predicted by our\nmode-coupling-like approach for the an equimolar binary hard sphere mixture\nwith particle size swaps with the non-ergodicity parameters predicted by the\nstandard mode-coupling theory for the same system without swaps. Our theory\npredicts that the \"cage size\" is bigger in the system with particle size swaps."
    },
    {
        "anchor": "Diffusion of single ellipsoids under quasi-2D confinements: We report video-microscopy measurements of the translational and rotational\nBrownian motions of isolated ellipsoidal particles in quasi-two-dimensional\nsample cells of increasing thickness. The long-time diffusion coefficients were\nmeasured along the long ($D_a$) and short ($D_b$) ellipsoid axes, respectively,\nand the ratio, $D_a/D_b$, was determined as a function of wall confinement and\nparticle aspect ratio. In three-dimensions this ratio ($D_a/D_b$) cannot be\nlarger than two, but wall confinement was found to substantially alter\ndiffusion anisotropy and substantially slow particle diffusion along the short\naxis.",
        "positive": "Birefringence of silica hydrogels prepared under high magnetic fields\n  reinvestigated: Birefringence is an indicator of structural anisotropy of materials. We\nmeasured the birefringence of Pb(II)-doped silica hydrogels prepared under a\nhigh magnetic field of various strengths. Because the silica is diamagnetic,\none does not expect the structural anisotropy induced by a magnetic field. In\nprevious work [Mori A, Kaito T, Furukawa H 2008 Mater. Lett. 62 3459-3461], we\nprepared samples in cylindrical cells made of borosilicate glass and obtained a\npreliminary result indicating a negative birefringence for samples prepared at\n5T with the direction of the magnetic field being the optic axis. We have\nmeasured the birefringence of Pn(II)-doped silica hydrogels prepared in square\ncross-sectional cells made of quartz and reverted the previous conclusion.\nInterestingly, the magnetic-influenced silica hydrogels measured have been\nclassified into four classes: two positive birefringent ones, no birefringent\none, and negative birefringent one. Proportionality between birefringence and\nthe strength of magnetic field is seen for the former two."
    },
    {
        "anchor": "Asymmetric crystallization during cooling and heating in model\n  glass-forming systems: We perform molecular dynamics (MD) simulations of the crystallization process\nin binary Lennard-Jones systems during heating and cooling to investigate\natomic-scale crystallization kinetics in glass-forming materials. For the\ncooling protocol, we prepared equilibrated liquids above the liquidus\ntemperature $T_l$ and cooled each sample to zero temperature at rate $R_c$. For\nthe heating protocol, we first cooled equilibrated liquids to zero temperature\nat rate $R_p$ and then heated the samples to temperature $T > T_l$ at rate\n$R_h$. We measured the critical heating and cooling rates $R_h^*$ and $R_c^*$,\nbelow which the systems begin to form a substantial fraction of crystalline\nclusters during the heating and cooling protocols. We show that $R_h^* >\nR_c^*$, and that the asymmetry ratio $R_h^*/R_c^*$ includes an intrinsic\ncontribution that increases with the glass-forming ability (GFA) of the system\nand a preparation-rate dependent contribution that increases strongly as $R_p\n\\rightarrow R_c^*$ from above. We also show that the predictions from classical\nnucleation theory (CNT) can qualitatively describe the dependence of the\nasymmetry ratio on the GFA and preparation rate $R_p$ from the MD simulations\nand results for the asymmetry ratio measured in Zr- and Au-based bulk metallic\nglasses (BMG). This work emphasizes the need for and benefits of an improved\nunderstanding of crystallization processes in BMGs and other glass-forming\nsystems.",
        "positive": "Computational Study of pKa shift of Aspartate residue in Thioredoxin:\n  Role of Configurational Sampling and Solvent Model: Alchemical free energy calculations are widely used in predicting pKa, and\nbinding free energy calculations in biomolecular systems. These calculations\nare carried out using either Free Energy Perturbation (FEP) or Thermodynamic\nIntegration (TI). Numerous efforts have been made to improve the accuracy and\nefficiency of such calculations, especially by boosting conformational\nsampling. In this paper, we use a technique that enhances the conformational\nsampling by temperature acceleration of collective variables for alchemical\ntransformations and applies it to the prediction of pKa of the buried Asp 26\nresidue in thioredoxin protein. We discuss the importance of enhanced sampling\nin the pKa calculations. The effect of the solvent models in the computed pKa\nvalues is also presented."
    },
    {
        "anchor": "Mutual diffusion of inclusions in freely-suspended smectic liquid\n  crystal films: We study experimentally and theoretically the hydrodynamic interaction of\npairs of circular inclusions in two-dimensional, fluid smectic membranes\nsuspended in air. By analyzing their Brownian motion, we find that the radial\nmutual mobilities of identical inclusions are independent of their size but\nthat the angular coupling becomes strongly size-dependent when their radius\nexceeds a characteristic hydrodynamic length. The observed dependence of the\nmutual mobilities on inclusion size is described well for arbitrary separations\nby a model that generalizes the Levine/MacKintosh theory of point-force\nresponse functions and uses a boundary-element approach to calculate the\nmobility matrix.",
        "positive": "Hierarchy of Periodic patterns in the twist-bend nematic phase of\n  mesogenic dimers: Several attractive properties of hydrocarbon-linked mesogenic dimers have\nbeen discovered, a major feature of these has been the ability of dimers under\nconfinement to form periodic patterns. At least six different types of\nstripe-like periodic patterns can be observed in these materials under various\nexperimental conditions. Our most recent finding is the discovery of\nmicrometre-scale periodic patterns at the N-Ntb phase transition interface, and\nsub-micrometre scale patterns in the Ntb phase. Layer-like sub-micrometre\npatterns were observed using three-photon excitation fluorescence polarizing\nmicroscopy, and these are being reported here."
    },
    {
        "anchor": "Conserving controversies of melting line of graphite and graphene: Investigation of melting line of graphite and liquid carbon has long history.\nHowever, up to now there are still numerous controversies in the field, for\ninstance, the melting temperatures obtained in different experiments are in\nvery bad agrement. In the present paper we compare several models of carbon\nwidely used in computational studies and the results of ab-initio simulations\nof liquid carbon. We show that the empirical models fail to reproduce the\nproperties of liquid carbon correctly. We also discuss the \"melting\" of\ngraphene.",
        "positive": "Topology and ground state degeneracy of tetrahedral smectic vesicles: Chemical design of block copolymers makes it possible to create polymer\nvesicles with tunable microscopic structure. Here we focus on a model of a\nvesicle made of smectic liquid-crystalline block copolymers at zero\ntemperature. The vesicle assumes a faceted tetrahedral shape and the smectic\nlayers arrange in a stack of parallel straight lines with topological defects\nlocalized at the vertices. We counted the number of allowed states at $T=0$.\nFor any fixed shape, we found a two-dimensional countable degeneracy in the\nsmectic pattern depending on the tilt angle between the smectic layers and the\nedge of the tetrahedral shell. For most values of the tilt angle, the smectic\nlayers contain spiral topological defects. The system can spontaneously break\nchiral symmetry when the layers organize into spiral patterns, composed of a\nbound pair of $+1/2$ disclinations. Finally, we suggest possible applications\nof tetrahedral smectic vesicles in the context of functionalizing defects and\nthe possible consequences of the spiral structures for the rigidity of the\nvesicle."
    },
    {
        "anchor": "The FCC-BCC-Fluid triple point for model pair interactions with variable\n  softness: It is demonstrated that the coordinates of the fcc-bcc-fluid triple point of\nvarious model systems are located in a relatively narrow region, when expressed\nin terms of the two proper variables, characterizing the softness and strength\nof the interaction force at the mean interparticle separation. This can be\nregarded as a consequence of the \"corresponding states principle\" for strongly\ninteracting particle systems we have put forward recently [S. A. Khrapak, M.\nChaudhuri, and G. E. Morfill, J. Chem. Phys. {\\bf 134}, 241101 (2011)]. The\nrelated possibilities to predict the existence and approximate location of the\nfcc-bcc-fluid triple point for a wide range of pair interactions with variable\nsoftness are illustrated. Relation of the obtained results to experimental\nstudies of complex (dusty) plasmas are briefly discussed.",
        "positive": "Chiral Structure of F-actin Bundle Formed by Multivalent Counterions?: The mechanism of multivalent counterion-induced bundle formation by\nfilamentous actin (F-actin) is studied using a coarse-grained model and\nmolecular dynamics simulation. Real diameter size, helically ordered charge\ndistribution and twist rigidity of F-actin are taken into account in our model.\nThe attraction between parallel F-actins induced by multivalent counterions is\nstudied in detail and it is found that the maximum attraction occurs between\ntheir closest charged domains. The model F-actins aggregate due to the\nlike-charge attraction and form closely packed bundles. Counterions are mostly\ndistributed in the narrowest gaps between neighboring F-actins inside the\nbundles and the channels between three adjacent F-actins correspond to low\ndensity of the counterions. Density of the counterions varies periodically with\na wave length comparable to the separation between consecutive G-actin monomers\nalong the actin polymers. Long-lived defects in the hexagonal order of F-actins\nin the bundles are observed that their number increases with increasing the\nbundles size. Combination of electrostatic interactions and twist rigidity has\nbeen found not to change the symmetry of F-actin helical conformation from the\nnative 13/6 symmetry. Calculation of zero-temperature energy of hexagonally\nordered model F-actins with the charge of the counterions distributed as\ncolumns of charge domains representing counterion charge density waves has\nshown that helical symmetries commensurate with the hexagonal lattice\ncorrespond to local minima of the energy of the system. The global minimum of\nenergy corresponds to 24/11 symmetry with the columns of charge domains\narranged in the narrowest gaps between the neighboring F-actins."
    },
    {
        "anchor": "Dynamics of active defects on the anisotropic surface of an ellipsoidal\n  droplet: Cells are fundamental building blocks of living organisms displaying an array\nof shapes, morphologies, and textures that encode specific functions and\nphysical behaviors. Elucidating the rules of this code remains a challenge. In\nthis work, we create biomimetic structural building blocks by coating\nellipsoidal droplets of a smectic liquid crystal with a protein-based active\ncytoskeletal gel, thus obtaining core-shell structures. By exploiting the\npatterned texture and anisotropic shape of the smectic core, we were able to\nmold the complex nematodynamics of the interfacial active material and identify\nnew time-dependent states where topological defects periodically oscillate\nbetween rotational and translational regimes. Our nemato-hydrodynamic\nsimulations of active nematics demonstrate that, beyond topology and activity,\nthe dynamics of the active material are profoundly influenced by the local\ncurvature and smectic texture of the droplet, as well as by external\nhydrodynamic forces.\n  These results illustrate how the incorporation of these constraints into\nactive nematic shells orchestrates remarkable spatio-temporal motifs, offering\ncritical new insights into biological processes and providing compelling\nprospects for designing bio-inspired micro-machines.",
        "positive": "Electrophoretic separation of large DNAs using steric confinement: We report an alternative method for electrophoretic separation of large DNAs\nusing steric confinement between solid walls, without gel or obstacles. The\nchange of electrophoretic mobility vs confinement thickness is investigated\nusing fluorescence video microscopy. We observe separation at small confinement\nthicknesses followed by a transition to the bulk behaviour (no separation) at a\nthickness of about 4 &#956;m (a few radii of gyration for the studied DNA\nchains). We present tentative explanations of our original observations."
    },
    {
        "anchor": "Understanding the physics of hydrophobic solvation: Simulations of water near extended hydrophobic spherical solutes have\nrevealed the presence of a region of depleted density and accompanying enhanced\ndensity fluctuations.The physical origin of both phenomena has remained\nsomewhat obscure. We investigate these effects employing a mesoscopic binding\npotential analysis, classical density functional theory (DFT) calculations for\na simple Lennard-Jones (LJ) solvent and Grand Canonical Monte Carlo (GCMC)\nsimulations of a monatomic water (mw) model. We argue that the density\ndepletion and enhanced fluctuations are near-critical phenomena. Specifically,\nwe show that they can be viewed as remnants of the critical drying surface\nphase transition that occurs at bulk liquid-vapor coexistence in the\nmacroscopic planar limit, i.e.~as the solute radius $R_s\\to\\infty$. Focusing on\nthe radial density profile $\\rho(r)$ and a sensitive spatial measure of\nfluctuations, the local compressibility profile $\\chi(r)$, our binding\npotential analysis provides explicit predictions for the manner in which the\nkey features of $\\rho(r)$ and $\\chi(r)$ scale with $R_s$, the strength of\nsolute-water attraction $\\varepsilon_{sf}$, and the deviation from liquid-vapor\ncoexistence of the chemical potential, $\\delta\\mu$. These scaling predictions\nare confirmed by our DFT calculations and GCMC simulations. As such our theory\nprovides a firm basis for understanding the physics of hydrophobic solvation.",
        "positive": "Periodically driven DNA: Theory and simulation: We propose a generic model of driven DNA under the influence of an\noscillatory force of amplitude $F$ and frequency $\\nu$ and show the existence\nof a dynamical transition for a chain of finite length. We find that the area\nof the hysteresis loop, $A_{\\rm loop}$, scales with the same exponents as\nobserved in a recent study based on a much more detailed model. However,\ntowards the true thermodynamic limit, the high-frequency scaling regime extends\nto lower frequencies for larger chain length $L$ and the system has only one\nscaling ($A_{\\rm loop} \\approx \\nu^{-1}F^2)$. Expansion of an analytical\nexpression for $A_{\\rm loop}$ obtained for the model system in the low-force\nregime revealed that there is a new scaling exponent associated with force\n($A_{\\rm loop} \\approx \\nu^{-1}F^{2.5}$), which has been validated by\nhigh-precision numerical calculation. By a combination of analytical and\nnumerical arguments, we also deduce that for large but finite $L$, the\nexponents are robust and independent of temperature and friction coefficient."
    },
    {
        "anchor": "Inverse design of soft materials via a deep-learning-based evolutionary\n  strategy: Colloidal self-assembly -- the spontaneous organization of colloids into\nordered structures -- has been considered key to produce next-generation\nmaterials. However, the present-day staggering variety of colloidal building\nblocks and the limitless number of thermodynamic conditions make a systematic\nexploration intractable. The true challenge in this field is to turn this logic\naround, and to develop a robust, versatile algorithm to inverse design colloids\nthat self-assemble into a target structure. Here, we introduce a generic\ninverse design method to efficiently reverse-engineer crystals, quasicrystals,\nand liquid crystals by targeting their diffraction patterns. Our algorithm\nrelies on the synergetic use of an evolutionary strategy for parameter\noptimization, and a convolutional neural network as an order parameter, and\nprovides a new way forward for the inverse design of experimentally feasible\ncolloidal interactions, specifically optimized to stabilize the desired\nstructure.",
        "positive": "NVU dynamics. II. Comparing to four other dynamics: In the companion paper [Ingebrigtsen et al., arXiv:1012.3447] an algorithm\nwas developed for tracing out a geodesic curve on the constant-potential-energy\nhypersurface. Here simulations of this NVU dynamics are compared to results for\nfour other dynamics, both deterministic and stochastic. First, NVU dynamics is\ncompared to the standard energy-conserving Newtonian NVE dynamics by\nsimulations of the Kob-Andersen binary Lennard-Jones liquid, its WCA version\n(i.e., with cut-off's at the pair potential minima), and the Gaussian\nLennard-Jones liquid. We find identical results for all quantities probed:\nradial distribution functions, incoherent intermediate scattering functions,\nand mean-square displacement as function of time. Arguments are then presented\nfor the equivalence of NVU and NVE dynamics in the thermodynamic limit; in\nparticular to leading order in 1/N these two dynamics give identical\ntime-autocorrelation functions. In the final section NVU dynamics is compared\nto Monte Carlo dynamics, to a diffusive dynamics of small-step random walks on\nthe constant-potential-energy hypersurface, and to Nose-Hoover NVT dynamics. If\ntime is scaled for the two stochastic dynamics to make their single-particle\ndiffusion constants identical to those of NVE dynamics, the simulations show\nthat all five dynamics are equivalent at low temperatures except at short\ntimes."
    },
    {
        "anchor": "On the transport of CO$_2$ through humidified facilitated transport\n  membranes: Membrane-based CO$_2$ removal from exhaust streams has recently gained much\nattention as a means of reducing emissions and limiting climate change. Novel\nmembranes for CO$_2$ removal include so called facilitated transport membranes\n(FTMs), which offer very high selectivities for CO$_2$ while maintaining decent\npermeabilities. Recently, these FTMs have been scaled up from laboratory level\nto plant-sized pilot modules with promising results. However, the molecular\ndetails of CO$_2$ transport in these has not yet been fully unraveled. In this\nwork, experimental studies were combined with quantum-mechanical ab initio\nmolecular dynamics simulations to gain insight into the underlying molecular\nmechanism of CO$_2$ permeation through FTMs. Various compositions of polyvinyl\nalcohol (PVA) as the membrane matrix with polyvinyl amine (PVAm),\nmonoethanolamine (MEA), or 4-amino-1-butanol (BA) as carrier molecules were\nexperimentally tested. Our experiments revealed that water was essential for\nthe CO$_2$ transport and a transport superposition was achieved with a mixed\ncomposition of PVAm and MEA in PVA. Furthermore, sorption measurements with PVA\nwere conducted with humidified N$_2$ and CO$_2$ to quantify water\nsorption-induced swelling and its contribution to the gas uptake. As the\ncarbonic acid--amine interaction is assumed to cause transport facilitation,\nelectronic structure-based ab initio molecular dynamics simulations were\nconducted to study the transport of CO$_2$ in the form of carbonic acid along\nPVAm polymer chains. In particular, the necessity of local water for transport\nfacilitation was studied at different water contents. The simulations show that\ntransport is fastest in the system with low water content and does not happen\nin the absence of water.",
        "positive": "Spontaneous membrane formation and self-encapsulation of active rods in\n  an inhomogeneous motility field: We study the collective dynamics of self-propelled rods in an inhomogeneous\nmotility field. At the interface between two regions of constant but different\nmotility, a smectic rod layer is spontaneously created through aligning\ninteractions between the active rods, reminiscent of an artificial,\nsemi-permeable membrane. This \"active membrane\" engulfes rods which are locally\ntrapped in low-motility regions and thereby further enhances the trapping\nefficiency by self-organization, an effect which we call \"self-encapsulation\".\nOur results are gained by computer simulations of self-propelled rod models\nconfined on a two-dimensional planar or spherical surface with a stepwise\nconstant motility field, but the phenomenon should be observable in any\ngeometry with sufficiently large spatial inhomogeneity. We also discuss\npossibilities to verify our predictions of active-membrane formation in\nexperiments of self-propelled colloidal rods and vibrated granular matter."
    },
    {
        "anchor": "Generalized Langevin Equation Formulation for Anomalous Polymer Dynamics: For reproducing the anomalous -- i.e., sub- or super-diffusive -- behavior in\nsome stochastic dynamical systems, the Generalized Langevin Equation (GLE) has\ngained considerable popularity in recent years. Motivated by the question\nwhether or not a system with anomalous dynamics can have the GLE formulation,\nhere I consider polymer physics, where sub-diffusive behavior is commonplace. I\nprovide an exact derivation of the GLE for phantom Rouse polymers, andby\nidentifying polymeric response to local strains, I argue the case for the GLE\nformulation for self-avoiding polymers and polymer translocation through a\nnarrow pore in a membrane. The number of instances in polymer physics, where\nthe anomalous dynamics corresponds to the GLE, thus seems to be fairly common.",
        "positive": "A constitutive law for cross-linked actin networks by homogenization\n  techniques: Inspired by experiments on the actin driven propulsion of micrometer sized\nbeads we develop and study a minimal mechanical model of a two-dimensional\nnetwork of stiff elastic filaments grown from the surface of a cylinder.\nStarting out from a discrete model of the network structure and of its\nmicroscopic mechanical behavior we derive a macroscopic constitutive law by\nhomogenization techniques. We calculate the axisymmetric equilibrium state and\nstudy its linear stability depending on the microscopic mechanical properties.\nWe find that thin networks are linearly stable, whereas thick networks are\nunstable. The critical thickness for the change in stability depends on the\nratio of the microscopic elastic constants. The instability is induced by the\nincrease in the compressive load on the inner network layers as the thickness\nof the network increases. The here employed homogenization approach combined\nwith more elaborate microscopic models can serve as a basis to study the\nevolution of polymerizing actin networks and the mechanism of actin driven\nmotion."
    },
    {
        "anchor": "Crack Nucleation in the Adhesive Wear of an Elastic-Plastic Half-Space: The detachment of material in an adhesive wear process is driven by a\nfracture mechanism which is controlled by a critical length-scale. Previous\nefforts in multi-asperity wear modeling have applied this microscopic process\nto rough elastic contact. However, experimental data shows that the assumption\nof purely elastic deformation at rough contact interfaces is unrealistic, and\nthat asperities in contact must deform plastically to accommodate the large\ncontact stresses. We therefore investigate the consequences of plastic\ndeformation on the macro-scale wear response using novel elastoplastic contact\nsimulations. The crack nucleation process at a rough contact interface is\nanalyzed in a comparative study with a classical $J_2$ plasticity approach and\na saturation plasticity model. We show that plastic residual deformations in\nthe $J_2$ model heighten the surface tensile stresses, leading to a higher\ncrack nucleation likelihood for contacts. This effect is shown to be stronger\nwhen the material is more ductile. We also show that elastic interactions\nbetween contacts can increase the likelihood of individual contacts nucleating\ncracks, irrespective of the contact constitutive model. This is supported by a\nstatistical approach we develop based on a Greenwood--Williamson model modified\nto take into account the elastic interactions between contacts and the shear\nstrength of the contact junction.",
        "positive": "Challenges in modelling diffusiophoretic transport: The methodology to simulate transport phenomena in bulk systems is\nwell-established. In contrast, there is no clear consensus about the choice of\ntechniques to model cross-transport phenomena and phoretic transport, mainly\nbecause some of the hydrodynamic descriptions are incomplete from a\nthermodynamic point of view. In the present paper, we use a unified framework\nto describe diffusio-osmosis(phoresis), and we report non-equilibrium Molecular\nDynamics (NEMD) on such systems. We explore different simulation methods to\nhighlight some of the technical problems that arise in the calculations. For\ndiffusiophoresis, we use two NEMD methods: boundary-driven and field-driven.\nAlthough the two methods should be equivalent in the limit of very weak\ngradients, we find that finite Peclet-number effects are much stronger in\nboundary-driven flows than in the case where we apply fictitious color forces."
    },
    {
        "anchor": "Dynamic heterogeneity and non-Gaussian behavior in a model supercooled\n  liquid: We use a recently-derived reformulation of the diffusion constant [Stillinger\nF H and Debenedetti P G 2005 J. Phys. Chem. B 109 6604] to investigate\nheterogeneous dynamics and non-Gaussian diffusion in a binary Lennard-Jones\nmixture. Our work focuses on the joint probability distribution of particles\nwith velocity v_0 at time t=0 and eventual displacement Delta x at time t=Delta\nt. We show that this distribution attains a distinctive shape at the time of\nmaximum non-Gaussian behavior in the supercooled liquid. By performing a\ntwo-Gaussian fit of the displacement data, we obtain, in a non-arbitrary\nmanner, two diffusive length scales inherent to the supercooled liquid and use\nthem to identify spatially separated regions of mobile and immobile particles.",
        "positive": "Phase behaviors of binary mixtures composed of banana-shaped and\n  calamitic mesogens: In this work, five mixtures with different concentrations of banana-shaped\nand calamitic compounds have been prepared and subsequently studied by\npolarizing optical microscopy, differential scanning calorimetry, and X-ray\ndiffraction on non-oriented samples. The phase sequences and molecular\nparameters of the binary systems are presented."
    },
    {
        "anchor": "Chain deformation helps translocation: Deformation of single stranded DNA in translocation process before reaching\nthe pore is investigated. By solving the Laplace equation in a suitable\ncoordinate system and with appropriate boundary conditions, an approximate\nsolution for the electric field inside and outside of a narrow pore is\nobtained. With an analysis based on \"electrohydrodynamic equivalence\" we\ndetermine the possibility of extension of a charged polymer due to the presence\nof an electric field gradient in the vicinity of the pore entrance. With a\nmulti-scale hybrid simulation (LB-MD), it is shown that an effective\ndeformation before reaching the pore occurs which facilitates the process of\nfinding the entrance for the end monomers. We also highlight the role of long\nrange hydrodynamic interactions via comparison of the LB-MD results with those\nobtained using a Langevin thermostat instead of the LB solver.",
        "positive": "Davydov's soliton in an external alternating magnetic field: The influence of an external oscillating in time magnetic field on the\ndynamics of the Davydov's soliton is investigated. It is shown that it\nessentially depends not only on the amplitude and frequency of the magnetic\nfield, but also on the field orientation with respect to the molecular chain\naxis. The soliton velocity and phase are calculated. They are oscillating in\ntime functions with the frequency of the main harmonic, given by the external\nfield frequency, and higher multiple harmonics. It is concluded that such\ncomplex effects of external time-depending magnetic fields on the dynamics of\nsolitons modify the charge transport in low-dimensional molecular systems,\nwhich can affect functioning of the devices based on such systems. These\nresults suggest also the physical mechanism of therapeutic effects of\noscillating magnetic fields, based on the field influence on the dynamics of\nsolitons which provide charge transport through biological macro-molecules in\nthe redox processes."
    },
    {
        "anchor": "A Novel Algorithm for the Estimation of the Surfactant Surface Excess at\n  Emulsion Interfaces: When the theoretical values of the interfacial tension -resulting from the\nhomogeneous distribution of ionic surfactant molecules amongst the interface of\nemulsion drops- are plotted against the total surfactant concentration, they\nproduce a curve comparable to the Gibbs adsorption isotherm. However, the\nactual isotherm takes into account the solubility of the surfactant in the\naqueous bulk phase. Hence, assuming that the total surfactant population is\nonly distributed among the available oil/water interfaces, one can calculate\nwhat surface concentration is necessary to reproduce the experimental values of\nthe interfacial tension. A similar procedure can be followed using the zeta\npotential of the drops as a standard for a given set of salt and surfactant\nconcentrations. We applied these procedures to the case of hexadecane/water\nnanoemulsions at different salt concentrations. This information was used to\ncompute typical interaction potentials between non-deformable nanoemulsion\ndrops. The results indicate that there are significant differences between the\nsurfactant population expected from macroscopic adsorption isotherms, and the\nactual surfactant popula- tion adsorbed to the surface of nanoemulsion drops.",
        "positive": "Orientation of plastic rearrangements in two-dimensional model glasses\n  under shear: The plastic deformation of amorphous solids is mediated by localized shear\ntransformations involving small groups of particles rearranging irreversibly in\nan elastic background. We introduce and compare three different computational\nmethods to extract the size and orientation of these shear transformations in\nsimulations of a two-dimensional (2D) athermal model glass under simple shear.\nWe find that the shear angles are broadly distributed around the macroscopic\nshear direction, with a more or less Gaussian distribution with a standard\ndeviation of around 20 $\\bullet$ about the direction of maximal local shear.\nThe distributions of sizes and orientations of shear transformations display no\nsubstantial sensitivity to the shear rate. These results can notably be used to\nrefine the description of rearrangements in elastoplastic models."
    },
    {
        "anchor": "Flexoelectricity and piezoelectricity - reason for rich variety of\n  phases in antiferroelectric liquid crystals: The free energy of antiferroelectric liquid crystal which takes into account\npolar order explicitly is presented. Steric, van der Waals, piezoelectric and\nflexoelectric interactions to the nearest layers and dipolar electrostatic\ninteractions to the nearest and to the next nearest layers induce indirect tilt\ninteractions with chiral and achiral properties, which extend to the third and\nto the fourth nearest layers. Chiral indirect interactions between tilts can be\nlarge and induce helicoidal modulations even in systems with negligible chiral\nvan der Waals interactions. If indirect chiral interactions compete with chiral\nvan der Waals interactions, the helix unwinding is possible. Although strength\nof microscopic interactions change monotonically with decreasing temperature,\neffective interlayer interactions change nonmonotonically and give rise to\nnonmonotouous change of modulation period through various phases. Increased\nenatiomeric excess i.e. increased chirality changes the phase sequence.",
        "positive": "Binary separation in very thin nematic films: thickness and phase\n  coexistence: The behavior as a function of temperature of very thin films (10 to 200 nm)\nof pentylcyanobiphenyl (5CB) on silicon substrates is reported. In the vicinity\nof the nematic/isotropic transition we observe a coexistence of two regions of\ndifferent thicknesses: thick regions are in the nematic state while thin ones\nare in the isotropic state. Moreover, the transition temperature is shifted\ndownward following a 1/h^2 law (h is the film thickness). Microscope\nobservations and small angle X-ray scattering allowed us to draw a phase\ndiagram which is explained in terms of a binary first order phase transition\nwhere thickness plays the role of an order parameter."
    },
    {
        "anchor": "Interactions of neutral semipermeable shells in asymmetric electrolyte\n  solutions: We study the ionic equilibria and interactions of neutral semi-permeable\nspherical shells immersed in electrolyte solutions, including polyions.\nAlthough the shells are uncharged, only one type of ions of the electrolyte can\npermeate them, thus leading to a steric charge separation in the system. This\ngives rise to a charge accumulation inside the shell and a build up of\nconcentration- dependent shell potential, which converts into a disjoining\npressure between the neighboring shells. These are quantified by using the\nPoisson-Boltzmann and integral equations theory. In particular, we show that in\ncase of low valency electrolytes, interactions between shells are repulsive and\ncan be sufficiently strong to stabilize the shell dispersion. In contrast, the\ncharge correlation effects in solutions of polyvalent ions result in\nattractions between the shells, with can lead to their aggregation.",
        "positive": "Orientational ordering of closely packed Janus particles: We study orientational ordering of $2$-dimensional closely packed Janus\nparticles by extensive Monte Carlo simulations. For smaller patch sizes the\nsystem remains in the plastic crystal phase where the rotational degrees of\nfreedom are disordered down to the lowest temperatures. There the liquid\nconsist of dimers and trimers of the attractive patches. For large enough patch\nsizes, the system exhibits a thermodynamic transition into a phase with stripe\npatterns of the patches breaking the three-fold rotational symmetry. Our\nresults strongly suggests that the latter is a 2nd order phase transition whose\nuniversality is the same as that of the $3$-state Potts model in\n$2$-dimensions. Furthermore we analyzed the relaxation dynamics of the system\nperforming quenching simulations into the stripe phase. We found growing\ndomains of the stripes. The relaxation of key dynamical quantities follow\nuniversal scaling features in terms of the domain size."
    },
    {
        "anchor": "Effective temperatures and activated dynamics for a two-dimensional\n  air-driven granular system on two approaches to jamming: We present experiments on several distinct effective temperatures in a\ngranular system at a sequence of increasing packing densities and at a sequence\nof decreasing driving rates. This includes single-grain measurements based on\nthe mechanical energies of both the grains and an embedded oscillator, as well\nas a collective measurement based on the Einstein relation between diffusivity\nand mobility, which all probe different time scales. Remarkably, all effective\ntemperatures agree. Furthermore, mobility data along the two trajectories\ncollapse when plotted vs effective temperature and exhibit an Arrhenius form\nwith the same energy barrier as the microscopic relaxation time.",
        "positive": "Stress management in composite biopolymer networks: Living tissues show an extraordinary adaptiveness to strain, which is crucial\nfor their proper biological functioning. The physical origin of this mechanical\nbehaviour has been widely investigated using reconstituted networks of collagen\nfibres, the principal load-bearing component of tissues. However, collagen\nfibres in tissues are embedded in a soft hydrated polysaccharide matrix which\ngenerates substantial internal stresses whose effect on tissue mechanics is\nunknown. Here, by combining mechanical measurements and computer simulations,\nwe show that networks composed of collagen fibres and a hyaluronan matrix\nexhibit synergistic mechanics characterized by an enhanced stiffness and\ndelayed strain-stiffening. We demonstrate that the polysaccharide matrix has a\ndual effect on the composite response involving both internal stress and\nelastic reinforcement. Our findings elucidate how tissues can tune their\nstrain-sensitivity over a wide range and provide a novel design principle for\nsynthetic materials with programmable mechanical properties."
    },
    {
        "anchor": "Crescent Singularities in Crumpled Sheets: We examine the crescent singularity of a developable cone in a setting\nsimilar to that studied by Cerda et al [Nature 401, 46 (1999)]. Stretching is\nlocalized in a core region near the pushing tip and bending dominates the outer\nregion. Two types of stresses in the outer region are identified and shown to\nscale differently with the distance to the tip. Energies of the d-cone are\nestimated and the conditions for the scaling of core region size R_c are\ndiscussed. Tests of the pushing force equation and direct geometrical\nmeasurements provide numerical evidence that core size scales as R_c ~ h^{1/3}\nR^{2/3}, where h is the thickness of sheet and R is the supporting container\nradius, in agreement with the proposition of Cerda et al. We give arguments\nthat this observed scaling law should not represent the asymptotic behavior.\nOther properties are also studied and tested numerically, consistent with our\nanalysis.",
        "positive": "Orientational correlations in active and passive nematic defects: We investigate the emergence of orientational order among +1/2 disclinations\nin active nematic liquid crystals. Using a combination of theoretical and\nexperimental methods, we show that +1/2 disclinations have short-range\nantiferromagnetic alignment, as a consequence of the elastic torques\noriginating from their polar structure. The presence of intermediate -1/2\ndisclinations, however, turns this interaction from anti-aligning to aligning\nat scales that are smaller than the typical distance between like-sign defects.\nNo long-range orientational order is observed. Strikingly, these effects are\ninsensitive to material properties and qualitatively similar to what is found\nfor defects in passive nematic liquid crystals."
    },
    {
        "anchor": "Self-organising Dissipative Polymer Structures: In frameworks of the scaling theory of phase transitions and critical\nphenomena the quantitative dependence of macroscopic properties on\nnanostructural parameters in a polymeric material is revealed. The draw ratios\nat neck and at break are referred to the macroscopic properties. The structure\nis characterized by an average thickness of amorphous layers in isotropic\nmelt-crystallized linear high density polyethylene which is chosen as an\nexample. The square of the neck draw ratio is equal to the product of the\nsquare of the draw ratio at break and the chain ends collision probability.\nThis probability in its turn is proportional to the average thickness of\namorphous layers in the isotropic material. The neck draw ratio is a parameter\nof order. Polymers with flexible chains are solutions in solid state as well as\nin melt, the interacting ends of a marked chain serving as a solvent. At\ncritical polymerization degree all the phases are identical. This research is\nan important contribution to the molecular theory of polymer liquids. It has\nbeen found that the melt viscosity vs the molecular weight of linear\nflexible-chain polymer follows the power law with the 3.4-exponent within the\nreptation model near the critical point. This is different from the value 3\nexpected for the melt of ring macromolecules. The rotation vibration precession\nmotion of chain ends about the polymer melt flow direction were taken into\naccount to find better agreement with the experiment.",
        "positive": "Bulk and Collective Properties of a Dilute Fermi Gas in the BCS-BEC\n  Crossover: We investigate the zero-temperature properties of a dilute two-component\nFermi gas with attractive interspecies interaction in the BCS-BEC crossover. We\nbuild an efficient parametrization of the energy per particle based on Monte\nCarlo data and asymptotic behavior. This parametrization provides, in turn,\nanalytical expressions for several bulk properties of the system such as the\nchemical potential, the pressure and the sound velocity. In addition, on the\nbasis of a local polytropic equation of state, we determine the collective\nmodes of the Fermi gas under harmonic confinement in the framework of the\nhydrodynamic theory. The calculated collective frequencies are compared to\nexperimental data on confined vapors of $^6$Li atoms and with other theoretical\npredictions."
    },
    {
        "anchor": "In Search of Colloidal Hard Spheres: We recently reviewed the experimental determination of the volume fraction,\n$\\phi$, of hard-sphere colloids, and concluded that the absolute value of\n$\\phi$ was unlikely to be known to better than $\\pm 3$-6%. Here, in a second\npart to that review, we survey effects due to softness in the interparticle\npotential, which necessitates the use of an {\\em effective} volume fraction. We\nreview current experimental systems, and conclude that the one that most\nclosely approximates hard spheres remains polymethylmethacrylate spheres\nsterically stabilised by polyhydroxystearic acid `hairs'. For these particles\ntheir effective hard sphere diameter is around 1-10% larger than the core\ndiameter, depending on the particle size. We argue that for larger colloids\nsuitable for confocal microscopy, the effect of electrostatic charge cannot be\nneglected, so that mapping to hard spheres must be treated with caution.",
        "positive": "Action-derived molecular dynamics in the study of rare events: We present a practical method to generate classical trajectories with fixed\ninitial and final boundary conditions. Our method is based on the minimization\nof a suitably defined discretized action. The method finds its most natural\napplication in the study of rare events. Its capabilities are illustrated by\nnon-trivial examples. The algorithm lends itself to straightforward\nparallelization, and when combined with molecular dynamics (MD) it promises to\noffer a powerful tool for the study of chemical reactions."
    },
    {
        "anchor": "The restricted primitive model of ionic fluids with nonadditive\n  diameters: The restricted primitive model with nonadditive hard-sphere diameters is\nshown to have interesting and peculiar clustering properties. We report\naccurate calculations of the cluster concentrations. Implementing efficient and\nad hoc Monte Carlo algorithms we determine the effect of nonadditivity on both\nthe clustering and the gas-liquid binodal. For negative nonadditivity, tending\nto the extreme case of completely overlapping unlike ions, the prevailing\nclusters are made of an even number of particles having zero total charge. For\npositive nonadditivity, the frustrated tendency to segregation of like\nparticles and the reduced space available to the ions favors percolating\nclusters at high densities.",
        "positive": "From random walk to single-file diffusion: We report an experimental study of diffusion in a quasi-one-dimensional (q1D)\ncolloid suspension which behaves like a Tonks gas. The mean squared\ndisplacement as a function of time is described well with an ansatz\nencompassing a time regime that is both shorter and longer than the mean time\nbetween collisions. This ansatz asserts that the inverse mean squared\ndisplacement is the sum of the inverse mean squared displacement for short time\nnormal diffusion (random walk) and the inverse mean squared displacement for\nasymptotic single-file diffusion (SFD). The dependence of the single-file 1D\nmobility on the concentration of the colloids agrees quantitatively with that\nderived for a hard rod model, which confirms for the first time the validity of\nthe hard rod SFD theory. We also show that a recent SFD theory by Kollmann\nleads to the hard rod SFD theory for a Tonks gas."
    },
    {
        "anchor": "Conjecture on the lateral growth of type I collagen fibrils: Type I collagen fibrils have circular cross sections with radii mostly\ndistributed in between 50 and 100 nm and are characterized by an axial banding\npattern with a period of 67 nm. The constituent long molecules of those\nfibrils, the so-called triple helices, are densely packed but their nature is\nsuch that their assembly must conciliate two conflicting requirements : a\ndouble-twist around the axis of the fibril induced by their chirality and a\nperiodic layered organization, corresponding to the axial banding, built by\nspecific lateral interactions. We examine here how such a conflict could\ncontribute to the control of the radius of a fibril. We develop our analysis\nwith the help of two geometrical archetypes : the Hopf fibration and the\nalgorithm of phyllotaxis. The first one provides an ideal template for a\ntwisted bundle of fibres and the second ensures the best homogeneity and local\nisotropy possible for a twisted dense packing with circular symmetry. This\napproach shows that, as the radius of a fibril with constant double-twist\nincreases, the periodic layered organization can not be preserved without\nmoving from planar to helicoidal configurations. Such changes of configurations\nare indeed made possible by the edge dislocations naturally present in the\nphyllotactic pattern where their distribution is such that the lateral growth\nof a fibril should stay limited in the observed range. Because of our limited\nknowledge about the elastic constants involved, this purely geometrical\ndevelopment stays at a quite conjectural level.",
        "positive": "On the effect of temperature on the reentrant condensation in\n  polyelectrolyte-liposome complexation: In systems of highly charged linear polyelectrolytes and oppositely charged\ncolloidal particles, long-lived clusters of polyelectrolyte-decorated particles\nform in an interval of concentrations around the isoelectric point, where\nreentrant condensation connected to charge inversion of cluster is observed.\nThe mechanisms that drive the aggregation and stabilize, at the different\npolymer/particle ratios, a well defined size of the aggregates are not\ncompletely understood. Moreover, a central question still remains unanswered,\ni.e., whether the clusters are true equilibrium or metastable aggregates. To\nelucidate this point, in this work, we have investigated the effect of the\ntemperature on the formation of the clusters. We employed liposomes built up by\nDOTAP lipid interacting with a simple anionic polyion, sodium polyacrylate,\nover an extended concentration range below and over the isoelectric condition.\nOur results show that the aggregation process can be described by a\nthermally-activated mechanism."
    },
    {
        "anchor": "Microstructure Formation in Freezing Nanosuspension Droplets: The structural evolution of suspensions upon freezing is studied with optical\nmicroscopy in a suspended droplet configuration. Droplets have millimeter size\nand consist in an aqueous mixture of silica particles while the surroundings\nphase is hexane. Freeze-thaw cycles are applied to this system and a two-step\nfreezing mechanism evidenced. A fast adiabatic growth of dendrites that invade\nthe full droplets is first observed, and occurs within a few milliseconds. Then\na slow process lasts for several seconds and corresponds to the release of\nsolidification latent heat into the hexane phase. The striking feature of this\nwork is to evidence that after the first freeze-thaw cycle flocculated\nmicrostructures are generated. When a second cycle is performed,\nmicrostructures further flocculate and generate, for dense silica suspensions,\nstable porous spheres of the size of the droplets. A phenomenological\ndescription based on repulsion or engulfment of particles by solidifying ice\nfronts is proposed.",
        "positive": "How patchiness controls the properties of chain-like assemblies of\n  colloidal platelets: Patchy colloidal platelets with convex, non-spherical shapes have been\nrealized with different materials at length scales ranging from nanometers to\nmicrons. While the assembly of these hard shapes tends to maximize edge-to-edge\ncontacts, as soon as a directional attraction is added -- by means of, e.g.,\nspecific ligands along the particle edges -- a competition between shape and\nbonding anisotropy sets in, giving rise to a complex assembly scenario. We\nfocus here on a two-dimensional system of patchy rhombi, i.e., colloidal\nplatelets with a regular rhombic shape decorated with bonding sites along their\nperimeter. Specifically, we consider rhombi with two patches, placed on either\nopposite or adjacent edges. While for the first particle class only chains can\nform, for the latter we observe the emergence of either chains or loops,\ndepending on the system parameters. According to the patch positioning --\nclassified in terms of different classes, topologies and distances from the\nedge center -- we are able to characterize the emerging chain-like assemblies\nin terms of length, packing abilities, flexibility properties and nematic\nordering."
    },
    {
        "anchor": "Three dimensional optical manipulation and structural imaging of soft\n  materials by use of laser tweezers and multimodal nonlinear microscopy: We develop an integrated system of holographic optical trapping and\nmultimodal nonlinear microscopy and perform simultaneous three-dimensional\noptical manipulation and non-invasive structural imaging of composite\nsoft-matter systems. We combine different nonlinear microscopy techniques such\nas coherent anti-Stokes Raman scattering, multi-photon excitation fluorescence\nand multi-harmonic generation, and use them for visualization of long-range\nmolecular order in soft materials by means of their polarized excitation and\ndetection. The combined system enables us to accomplish both, manipulation in\ncomposite soft materials such as colloidal inclusions in liquid crystals as\nwell as imaging of each separate constituents of the composite material in\ndifferent nonlinear optical modalities. We also demonstrate optical generation\nand control of topological defects and simultaneous reconstruction of their\nthree-dimensional long-range molecular orientational patterns from the\nnonlinear optical images.",
        "positive": "Elementary vibrational model for thermal conductivity of Lennard-Jones\n  fluids: Applicability domain and accuracy level: Exact mechanisms of thermal conductivity in liquids are not well understood,\ndespite rich research history. A vibrational model of energy transfer in dense\nsimple liquids with soft pairwise interactions seems adequate to partially fill\nthis gap. The purpose of the present paper is to define its applicability\ndomain and to demonstrate how well it works within the identified applicability\ndomain in the important case of the Lennard-Jones model system. The existing\nresults from molecular dynamics simulations are used for this purpose.\nAdditionally, we show that a freezing density scaling approach represents a\nvery powerful tool to estimate the thermal conductivity coefficient across\nessentially the entire gas-liquid region of the phase diagram, including\nmetastable regions. A simple practical expression serving this purpose is\nproposed."
    },
    {
        "anchor": "Ordering dynamics of blue phases entails kinetic stabilization of\n  amorphous networks: The cubic blue phases of liquid crystals are fascinating and technologically\npromising examples of hierarchically structured soft materials, comprising\nordered networks of defect lines (disclinations) within a liquid crystalline\nmatrix. We present the first large-scale simulations of their domain growth,\nstarting from a blue phase nucleus within a supercooled isotropic or\ncholesteric background. The nucleated phase is thermodynamically stable; one\nexpects its slow orderly growth, creating a bulk cubic. Instead, we find that\nthe strong propensity to form disclinations drives the rapid disorderly growth\nof a metastable amorphous defect network. During this process the original\nnucleus is destroyed; re-emergence of the stable phase may therefore require a\nsecond nucleation step. Our findings suggest that blue phases exhibit\nhierarchical behavior in their ordering dynamics, to match that in their\nstructure.",
        "positive": "Tunable critical Casimir forces counteract Casimir-Lifshitz attraction: Casimir forces in quantum electrodynamics emerge between microscopic metallic\nobjects because of the confinement of the vacuum electromagnetic fluctuations\noccurring even at zero temperature. Their generalization at finite temperature\nand in material media are referred to as Casimir--Lifshitz forces. These forces\nare typically attractive, leading to the widespread problem of stiction between\nthe metallic parts of micro- and nanodevices. Recently, repulsive Casimir\nforces have been experimentally realized but their reliance on specialized\nmaterials prevents their dynamic control and thus limits their further\napplicability. Here, we experimentally demonstrate that repulsive critical\nCasimir forces, which emerge in a critical binary liquid mixture upon\napproaching the critical temperature, can be used to actively control\nmicroscopic and nanoscopic objects with nanometer precision. We demonstrate\nthis by using critical Casimir forces to prevent the stiction caused by the\nCasimir--Lifshitz forces. We study a microscopic gold flake above a flat\ngold-coated substrate immersed in a critical mixture. Far from the critical\ntemperature, stiction occurs because of dominant Casimir--Lifshitz forces. Upon\napproaching the critical temperature, however, we observe the emergence of\nrepulsive critical Casimir forces that are sufficiently strong to counteract\nstiction. This experimental demonstration can accelerate the development of\nmicro- and nanodevices by preventing stiction as well as providing active\ncontrol and precise tunability of the forces acting between their constituent\nparts."
    },
    {
        "anchor": "Rheology of bidisperse non-Brownian suspensions: We study the rheology of bidisperse non-Brownian suspensions using\nparticle-based simulation, mapping the viscosity as a function of the size\nratio of the species, their relative abundance, and the overall solid content.\nThe variation of the viscosity with applied stress exhibits paradigmatic shear\nthickening phenomenology irrespective of composition, though the\nstress-dependent limiting solids fraction governing the viscosity and its\ndivergence point are non-monotonic in the mixing ratio. Contact force data\ndemonstrate an exchange in dominant stress contribution from large-large to\nsmall-small particle contacts as the mixing ratio of the species evolves.\nCombining a prior model for shear thickening with one for composition-dependent\njamming, we obtain a full description of the rheology of bidisperse\nnon-Brownian suspensions capable of predicting effects such as the viscosity\nreduction observed upon adding small particle fines to a suspension of large\nparticles.",
        "positive": "Kinetic theory of driven granular fluids: Granular matter under rapid flow conditions can be modeled as a granular gas,\nnamely, a gas of hard spheres dissipating part of their kinetic energy during\nbinary collisions (inelastic hard spheres, IHS). On the other hand, given that\ncollisions are inelastic one has to inject energy into the system to compensate\nfor the inelastic cooling and maintain it in rapid conditions. Although in real\nexperiments the external energy is supplied to the system by the boundaries, it\nis quite usual in computer simulations to heat the system by the action of an\nexternal driving force or thermostat. Despite thermostats have been widely\nemployed in the past, their influence on the dynamic properties of the system\n(for elastic and granular fluids) is not yet completely understood. In this\nwork, we determine the transport properties of driven granular systems by using\ntwo independent and complementary routes, one of them being analytic\n(Chapman-Enskog method, BGK solution and Grad's moments method) and the other\none being computational (Monte Carlo simulations)."
    },
    {
        "anchor": "Perturbative expansion for the half-integer rectilinear disclination\n  line in the Landau-de Gennes theory: The structure of the half-integer rectilinear disclination line within the\nframework of the Landau-de Gennes effective theory of nematic liquid crystals\nis investigated. The consistent perturbative expansion is constructed for the\ncase of $L_2\\neq 0$. It turns out that such expansion can be performed around\nonly a discrete subset of an infinite set of the degenerate zeroth order\nsolutions. These solutions correspond to the positive and negative wedge\ndisclination lines and to four configurations of the twist disclination line.\nThe first order corrections to both the order parameter field as well as the\nfree energy of the disclination lines have been found. The results for the free\nenergy are compared with the ones obtained in the Frank-Oseen-Zocher director\ndescription.",
        "positive": "Cell mechanics and signalisation: SARS-CoV-2 hijacks membrane liquid\n  crystals and cytoskeletal fractal topology: We highlight changes to cell signalling under virus invasion (SARS-CoV-2),\ninvolving disturbance of membranes and of nanodomains, modulated by the\ncytoskeleton. Virus alters the mechanical properties of the membranes,\nimpairing mesophase structures mediated by the fractal architecture initiated\nby actomyosin."
    },
    {
        "anchor": "Snapping Mechanical Metamaterials under Tension: We present a monolithic mechanical metamaterial comprising a periodic\narrangement of snapping units with tunable tensile behavior. Under tension, the\nmetamaterial undergoes a large extension caused by sequential snap-through\ninstabilities, and exhibits a pattern switch from an undeformed wavy-shape to a\ndiamond configuration. By means of experiments performed on 3D printed\nprototypes, numerical simulations and theoretical modeling, we demonstrate how\nthe snapping architecture can be tuned to generate a range of nonlinear\nmechanical responses including monotonic, S-shaped, plateau and non-monotonic\nsnap-through behavior. This work contributes to the development of design\nstrategies that allow programming nonlinear mechanical responses in solids.",
        "positive": "Collective hydrodynamic transport of magnetic microrollers: We investigate the collective transport properties of microscopic magnetic\nrollers that propel close to a surface due to a circularly polarized, rotating\nmagnetic field. The applied field exerts a torque to the particles, which\ninduces a net rolling motion close to a surface. The collective dynamics of the\nparticles result from the balance between magnetic dipolar interactions and\nhydrodynamic ones. We show that, when hydrodynamics dominate, i.e. for high\nparticle spinning, the collective mean velocity linearly increases with the\nparticle density. In this regime we analyse the clustering kinetics, and find\nthat hydrodynamic interactions between the anisotropic, elongated particles,\ninduce preferential cluster growth along a direction perpendicular to the\ndriving one, leading to dynamic clusters that easily break and reform during\npropulsion."
    },
    {
        "anchor": "Adhesive Loose Packings of Small Particles: We explore adhesive loose packings of dry small spherical particles of\nmicrometer size using 3D discrete-element simulations with adhesive contact\nmechanics. A dimensionless adhesion parameter ($Ad$) successfully combines the\neffects of particle velocities, sizes and the work of adhesion, identifying a\nuniversal regime of adhesive packings for $Ad>1$. The structural properties of\nthe packings in this regime are well described by an ensemble approach based on\na coarse-grained volume function that includes correlations between bulk and\ncontact spheres. Our theoretical and numerical results predict: (i) An equation\nof state for adhesive loose packings that appears as a continuation from the\nfrictionless random close packing (RCP) point in the jamming phase diagram;\n(ii) The existence of a maximal loose packing point at the coordination number\n$Z=2$ and packing fraction $\\phi=1/2^{3}$. Our results highlight that adhesion\nleads to a universal packing regime at packing fractions much smaller than the\nrandom loose packing, which can be described within a statistical mechanical\nframework. We present a general phase diagram of jammed matter comprising\nfrictionless, frictional, adhesive as well as non-spherical particles,\nproviding a classification of packings in terms of their continuation from the\nspherical frictionless RCP.",
        "positive": "Exact solution for the force-extension relation of a semiflexible\n  polymer under compression: Exact solutions for the elastic and thermodynamic properties for the wormlike\nchain model are elaborated in terms of Mathieu functions. The smearing of the\nclassical Euler buckling instability for clamped polymers is analyzed for the\nforce-extension relation. Interestingly, at strong compression forces the\nthermal fluctuations lead to larger elongations than for the elastic rod. The\nsusceptibility defined as the derivative of the force-extension relation\ndisplays a prominent maximum at a force that approaches the critical Euler\nbuckling force as the persistence length is increased. We also evaluate the\nexcess entropy and heat capacity induced by the compresssion and find that they\nvary non-monotonically with the load. These findings are corroborated by\npseudo-Brownian simulations."
    },
    {
        "anchor": "A framework for the analysis of fully coupled normal and tangential\n  contact problems with complex interfaces: An extension to the interface finite element with eMbedded Profile for Joint\nRoughness (MPJR interface finite element) is herein proposed for solving the\nfrictional contact problem between a rigid indenter of any complex shape and an\nelastic body under generic oblique load histories. The actual shape of the\nindenter is accounted for as a correction of the gap function. A regularised\nversion of the Coulomb friction law is employed for modeling the tangential\ncontact response, while a penalty approach is introduced in the normal contact\ndirection. The development of the finite element (FE) formulation stemming from\nits variational formalism is thoroughly derived and the model is validated in\nrelation to challenging scenarios for standard (alternative) finite element\nprocedures and analytical methods, such as the contact with multi-scale rough\nprofiles. The present framework enables the comprehensive investigation of the\nsystem response due to the occurrence of tangential tractions, which are at the\norigin of important phenomena such as wear and fretting fatigue, together with\nthe analysis of the effects of coupling between normal and tangential contact\ntractions. This scenario is herein investigated in relation to challenging\nphysical problems involving arbitrary loading histories.",
        "positive": "Kinetics of 2D-constrained orbitally-shaken particles: We present an experimental study of the kinetics of orbitally-shaken\nmacroscopic particles confined to a two-dimensional bounded domain. Discounting\nthe forcing action of the external periodic actuation, the particles show\ntranslational velocities and diffusivity consistent with a confined random walk\nmodel. Such experimental system may therefore represent a suitable macroscopic\nanalog to investigate aspects of molecular dynamics and self-assembly."
    },
    {
        "anchor": "Instabilities and Oscillations in Isotropic Active Gels: We present a generic formulation of the continuum elasticity of an isotropic\ncrosslinked active gel. The gel is described by a two-component model\nconsisting of an elastic network coupled frictionally to a permeating fluid.\nActivity is induced by active crosslinkers that undergo an ATP-activated cycle\nand transmit forces to the network. The on/off dynamics of the active\ncrosslinkers is described via rate equations for unbound and bound motors. For\nlarge activity motors yield a contractile instability of the network. At\nsmaller values of activity, the on/off motor dynamics provides an effective\ninertial drag on the network that opposes elastic restoring forces, resulting\nin spontaneous oscillations. Our work provides a continuum formulation that\nunifies earlier microscopic models of oscillations in muscle sarcomeres and a\ngeneric framework for the description of the large scale properties of\nisotropic active solids.",
        "positive": "Phase separation of binary fluids with dynamic temperature: Phase separation of binary fluids quenched by contact with cold external\nwalls is considered. Navier-Stokes, convection-diffusion, and energy equations\nare solved by lattice Boltzmann method coupled with finite-difference schemes.\nAt high viscosity, different morphologies are observed by varying the thermal\ndiffusivity. In the range of thermal diffusivities with domains growing\nparallel to the walls, temperature and phase separation fronts propagate\ntowards the inner of the system with power-law behavior. At low viscosity\nhydrodynamics favors rounded shapes, and complex patterns with different\nlengthscales appear. Off-symmetrical systems behave similarly but with more\nordered configurations."
    },
    {
        "anchor": "Contact values for disparate-size hard-sphere mixtures: A universality ansatz for the contact values of a multicomponent mixture of\nadditive hard spheres is used to propose new formulae for the case of\ndisparate-size binary mixtures. A comparison with simulation data and with a\nrecent proposal by Alawneh and Henderson for binary mixtures shows reasonably\ngood agreement with the predictions for the contact values of the large-large\nradial distribution functions. A discussion on the usefulness and limitations\nof the new proposals is also presented.",
        "positive": "Exceptional Anti-Icing Performance of Self-Impregnating Slippery\n  Surfaces: A heat exchange interface at subzero temperature in a water vapor\nenvironment, exhibits high probability of frost formation due to freezing\ncondensation, a factor that markedly decreases the heat transfer efficacy due\nto the considerable thermal resistance of ice. Here we report a novel strategy\nto delay ice nucleation on these types of solid-water vapor interfaces. With a\nprocess-driven mechanism, a self-generated liquid intervening layer immiscible\nto water, is deposited on a textured superhydrophobic surface and acts as a\nbarrier between the water vapor and the solid substrate. This liquid layer\nimparts remarkable slippery conditions resulting in high mobility of condensing\nwater droplets. A large increase of the ensuing ice coverage time is shown\ncompared to the cases of standard smooth hydrophilic or textured\nsuperhydrophobic surfaces. During deicing of these self-impregnating surfaces\nwe show an impressive tendency of ice fragments to skate expediting defrosting.\nRobustness of such surfaces is also demonstrated by operating them under\nsubcooling for at least 490hr without a marked degradation. This is attributed\nto the presence of the liquid intervening layer, which protects the substrate\nfrom hydrolyzation enhancing longevity and sustaining heat transfer efficiency."
    },
    {
        "anchor": "Non-uniform Curvature and Anisotropic Deformation Control Wrinkling\n  Patterns on Tori: We investigate wrinkling patterns in a tri-layer torus consisting of an\nexpanding thin outer layer, an intermediate soft layer and an inner core with a\ntunable shear modulus, inspired by pattern formation in developmental\nbiologies, such as follicle pattern formation during the development of chicken\nembryos. We show from large-scale finite element simulations that hexagonal\nwrinkling patterns form for stiff cores whereas stripe wrinkling patterns\ndevelop for soft cores. Hexagons and stripes co-exist to form hybrid patterns\nfor cores with intermediate stiffness. The governing mechanism for the pattern\ntransition is that the stiffness of the inner core controls the degree to which\nthe major radius of the torus expands this has a greater effect on deformation\nin the long direction as compared to the short direction of the torus. This\nanisotropic deformation alters stress states in the outer layer which change\nfrom biaxial (preferred hexagons) to uniaxial (preferred stripes) compression\nas the core stiffness is reduced. As the outer layer continues to expand,\nstripe and hexagon patterns will evolve into Zigzag and segmented labyrinth,\nrespectively. Stripe wrinkles are observed to initiate at the inner surface of\nthe torus while hexagon wrinkles start from the outer surface as a result of\ncurvature-dependent stresses in the torus. We further discuss the effects of\nelasticities and geometries of the torus on the wrinkling patterns.",
        "positive": "Coarsening and Aging of Lattice Polymers: Influence of Bond Fluctuations: We present results for the nonequilibrium dynamics of collapse for a model\nflexible homopolymer on simple cubic lattices with fixed and fluctuating bonds\nbetween the monomers. Results from our Monte Carlo simulations show that,\nphenomenologically, the sequence of events observed during the collapse are\nindependent of the bond criterion. While the growth of the clusters (of\nmonomers) at different temperatures exhibits a nonuniversal power-law behavior\nwhen the bonds are fixed, the introduction of fluctuations in the bonds by\nconsidering the existence of diagonal bonds produces a temperature independent\ngrowth, which can be described by a universal nonequilibrium finite-size\nscaling function with a non-universal metric factor. We also examine the\nrelated aging phenomenon, probed by a suitable two-time density-density\nautocorrelation function showing a simple power-law scaling with respect to the\ngrowing cluster size. Unlike the cluster-growth exponent $\\alpha_c $, the\nnonequilibrium autocorrelation exponent $\\lambda_C$ governing the aging during\nthe collapse, however, is independent of the bond type and strictly follows the\nbounds proposed by two of us in Phys. Rev. E 93, 032506 (2016) at all\ntemperatures."
    },
    {
        "anchor": "Bouncing of a projectile impacting a dense potato-starch suspension\n  layer: When a solid projectile is dropped onto a dense non-Brownian-particle\nsuspension, the action of an extremely large resistance force on the projectile\nresults in its drastic deceleration, followed by a rebound. In this study, we\nperform a set of simple experiments of dropping a solid-projectile impact onto\na dense potato-starch suspension. From the kinematic data of the projectile\nmotion, the restitution coefficient and timescale of the rebound are measured.\nBy assuming linear viscoelasticity, the effective transient elasticity and\nviscosity can be estimated. We additionally estimate the Stokes viscosity on a\nlonger timescale by measuring the slow sinking time of the projectile. The\nestimated elastic modulus and viscosity are consistent with separately measured\nprevious results. In addition, the effect of mechanical vibration on the\nviscoelasticity is examined. As a result, we find that the viscoelasticity of\nthe impacted dense suspension is not significantly affected by the mechanical\nvibration.",
        "positive": "Multiple interfaces in diffusional phase transitions in binary\n  mesogen-non-mesogen mixtures undergoing metastable phase separations: Theory and simulations of simultaneous chemical demixing and phase ordering\nare performed for a mixed order parameter system with an isotropic-isotropic\n(I-I) phase separation that is metastable with respect to an isotropic-nematic\n(I-N) phase ordering transition. Under certain conditions, the disordered phase\ntransforms into an ordered phase via the motion of a double front containing a\nmetastable phase produced by I-I demixing, a thermodynamically driven mechanism\nnot previously reported. Different kinetic regimes are found depending on the\nlocation of the initial conditions in the thermodynamic phase diagram and the\nratio between diffusional and nematic phase ordering mobilities. For a\ndiffusional process, depending if the temperature is above or below the\ncritical co-dissolution point, an inflection point or a phase separation takes\nplace in the depletion layer. This phase separation leads to the formation of a\nsecond interface where the separation of the two metastable isotropic phases\ngrows monotonically with time. The observed deviations from the typical Fickian\nconcentration profiles are associated with strong positive deviations of the\nmixture from ideality due to couplings between concentration and nematic\nordering. Although systems of interest include liquid crystalline\nnanocomposites, this novel mechanism may apply to any mixture that can undergo\nan order-disorder transition and demix."
    },
    {
        "anchor": "Lattice models of directed and semiflexible polymers in anisotropic\n  environment: We study the conformational properties of polymers in presence of extended\ncolumnar defects of parallel orientation. Two classes of macromolecules are\nconsidered: the so-called partially directed polymers with preferred\norientation along direction of the external stretching field and semiflexible\npolymers. We are working within the frames of lattice models: partially\ndirected self-avoiding walks (PDSAWs) and biased self-avoiding walks (BSAWs).\nOur numerical analysis of PDSAWs reveals, that competition between the\nstretching field and anisotropy caused by presence of extended defects leads to\nexisting of three characteristic length scales in the system. At each fixed\nconcentration of disorder we found a transition point, where the influence of\nextended defects is exactly counterbalanced by the stretching field. Numerical\nsimulations of BSAWs in anisotropic environment reveal an increase of polymer\nstiffness. In particular, the persistence length of semiflexible polymers\nincreases in presence of disorder.",
        "positive": "Q-dependent Collective Relaxation Dynamics of Glass-Forming Liquid\n  Ca0.4K0.6(NO3)1.4 Investigated by Wide-Angle Neutron Spin-Echo: Employing wide-angle neutron spin echo spectroscopy, we measured the\nQ-dependent coherent intermediate scattering function of the prototypical ionic\nglass former Ca0.4K0.6(NO3)1.4, in the equilibrium and supercooled liquid\nstates beyond the hydrodynamic regime. The data reveal a clear two-step\nrelaxation: an exponential fast process, and a stretched exponential slow alpha\nprocess. de Gennes narrowing is observed in all characteristic variables of the\nalpha process: the relaxation time, amplitude, and stretching exponent. At all\nlength scales probed, the relative amplitude of the alpha-relaxation decreases\nwith increasing temperature and levels off in the normal liquid state. The\ntemperature dependence of the stretching exponent and the relaxation time at\ndifferent Q's indicate that modifications of the relaxation mechanisms at the\nlocal length scales, manifested as temperature independent dynamic\nheterogeneity and smaller deviations from Arrhenius behavior, have occurred\neven above the alpha-beta (Johari-Goldstein) bifurcation temperature."
    },
    {
        "anchor": "The role of adhesion in contact mechanics: Adhesive [e.g. van der Waals] forces were not generally taken into account in\ncontact mechanics until 1971, when Johnson, Kendall and Roberts (JKR)\ngeneralized Hertz' solution for an elastic sphere using an energetic argument\nwhich we now recognize to be analogous to that used in linear elastic fracture\nmechanics. A significant result is that the load-displacement relation exhibits\ninstabilities in which approaching bodies `jump in' to contact, whereas\nseparated bodies `jump out' at a tensile `pull-off force'. The JKR approach has\nsince been widely used in other geometries, but at small length scales or for\nstiffer materials it is found to be less accurate. In conformal contact\nproblems, other instabilities can occur, characterized by the development of\nregular patterns of regions of large and small traction. All these\ninstabilities result in differences between loading and unloading curves and\nconsequent hysteretic energy losses. Adhesive contact mechanics has become\nincreasingly important in recent years with the focus on soft materials [which\ngenerally permit larger areas of the interacting surfaces to come within the\nrange of adhesive forces], nano-devices and the analysis of bio-systems.\nApplications are found in nature, such as insect attachment forces, in\nnano-manufacturing, and more generally in industrial systems involving rubber\nor polymer contacts. In this paper, we review the strengths and limitations of\nvarious methods for analyzing contact problems involving adhesive tractions,\nwith particular reference to the effect of the inevitable roughness of the\ncontacting surfaces.",
        "positive": "Rifts in Rafts: A particle raft floating on an expanding liquid substrate provides a\nmacroscopic analog for studying material failure. The time scales in this\nsystem allow both particle-relaxation dynamics and rift formation to be\nresolved. In our experiments, a raft, an aggregate of particles, is stretched\nuniaxially by the expansion of the air-liquid interface on which it floats. Its\nfailure morphology changes continuously with pulling velocity. This can be\nunderstood as a competition between two velocity scales: the speed of\nre-aggregation, in which particles relax towards a low-energy configuration\ndetermined by viscous and capillary forces, and the difference of velocity\nbetween neighboring particles caused by the expanding fluid. This competition\nselects the cluster length, i.e., the distance between adjacent rifts. A model\nbased on this competition is consistent with the experimental failure patterns."
    },
    {
        "anchor": "Shear-induced reinforcement in boehmite gels: a rheo-X-ray-scattering\n  study: Boehmite, an aluminum oxide hydroxide $\\gamma$-AlO(OH), is broadly used in\nthe form of particulate dispersions in industrial applications, e.g., for the\nfabrication of ceramics and catalyst supports or as a binder for extrusion\nprocesses. Under acidic conditions, colloidal boehmite dispersions at rest form\ngels, i.e., space-spanning percolated networks that behave as soft solids at\nrest, and yet yield and flow like liquids under large enough deformations. Like\nmany other colloidal gels, the solid-like properties of boehmite gels at rest\nare very sensitive to their previous mechanical history. Our recent work\n[Sudreau et al., J. Rheol. 66, 91-104 (2022), and Phys. Rev. Material 6,\nL042601 (2022)] has revealed such \\textit{memory effects}, where the shear\nexperienced prior to flow cessation drives the elasticity of boehmite gels:\nwhile gels formed following application of a shear rate $\\dot\\gamma_{\\rm p}$\nlarger than a critical value $\\dot\\gamma_{\\rm c}$ are insensitive to shear\nhistory, gels formed after application of $\\dot\\gamma_{\\rm p}<\\dot\\gamma_{\\rm\nc}$ display reinforced viscoelastic properties and non-negligible residual\nstresses. Here, we provide a microstructural scenario for these striking\nobservations by coupling rheometry and small-angle X-ray scattering.\nTime-resolved measurements for $\\dot\\gamma_{\\rm p} <\\dot\\gamma_{\\rm c}$ show\nthat scattering patterns develop an anisotropic shape that persists upon flow\ncessation, whereas gels exposed to $\\dot\\gamma_{\\rm p}>\\dot\\gamma_{\\rm c}$\ndisplay isotropic scattering patterns upon flow cessation. Moreover, as the\nshear rate applied prior to flow cessation is decreased below $\\dot\\gamma_{\\rm\nc}$, the level of anisotropy frozen in the sample microstructure grows\nsimilarly to the viscoelastic properties, thus providing a direct link between\nmechanical reinforcement and flow-induced microstructural anisotropy.",
        "positive": "Interfacial Partitioning Enhances Microextractionby Multicomponent\n  Nanodroplets: The sensitive and reliable in-droplet chemical analysis benefits from the\nenhanced partition of an analyte into the droplets. This work, we will show\nthat chemical reactions in surface nanodroplets can shift the partition of\nanalytes from a highly diluted solution to the droplets. Seven types of organic\nacids with partition coefficients (LgP) ranging from -0.7 to 1.87 are used as\nmodel analytes dissolved in an oil solution that are extracted from the flow\ninto aqueous nanodroplets immobilized on a substrate. The timescale of\nintegrated extraction and reaction in droplets was represented by the\ndecoloration time of the droplets. Our results show that the effective\ndistribution coefficient of the analyte can be decreased by 3 to 11 times of\nthe distribution coefficient of the analyte in the bulk liquids. The principle\nbehind the significantly shifted partition is proposed to be enhanced the\ntransfer of the analyte across the droplet surface. The chemical reaction in\nthe droplets enhances the partition of the analyte from a highly diluted\nsolution. Our results show that the interfacial behavior of the analyte may be\nadvantageous as it may improve extraction and partition. Such enhanced\nextraction may be leveraged for sensitive chemical detection using reactive\ndroplets."
    },
    {
        "anchor": "Topological effects in the thermal properties of knotted polymer rings: The topological effects on the thermal properties of several knot\nconfigurations are investigated using Monte Carlo simulations. In order to\ncheck if the topology of the knots is preserved during the thermal fluctuations\nwe propose a method that allows very fast calculations and can be easily\napplied to arbitrarily complex knots. As an application, the specific energy\nand heat capacity of the trefoil, the figure-eight and the $8_1$ knots are\ncalculated at different temperatures and for different lengths. Short-range\nrepulsive interactions between the monomers are assumed. The knots\nconfigurations are generated on a three-dimensional cubic lattice and sampled\nby means of the Wang-Landau algorithm and of the pivot method. The obtained\nresults show that the topological effects play a key role for short-length\npolymers. Three temperature regimes of the growth rate of the internal energy\nof the system are distinguished.",
        "positive": "A Spin-1 Representation for Dual-Funnel Energy Landscapes: The interconversion between left- and right-handed helical folds of a\npolypeptide defines a dual-funneled free energy landscape. In this context, the\nfunnel minima are connected through a continuum of unfolded conformations,\nevocative of the classical helix-coil transition. Physical intuition and recent\nconjectures suggest that this landscape can be mapped by assigning a left- or\nright-handed helical state to each residue. We explore this possibility using\nall-atom replica exchange molecular dynamics and an Ising-like model,\ndemonstrating that the energy landscape architecture is at odds with a\ntwo-state picture. A three-state model - left, right, and unstructured - can\naccount for most key intermediates during chiral interconversion. Competing\nfolds and excited conformational states still impose limitations on the scope\nof this approach. However, the improvement is stark: Moving from a two-state to\na three-state model decreases the fit error from 1.6 $k_B T$ to 0.3 $k_B T$\nalong the left-to-right interconversion pathway."
    },
    {
        "anchor": "Stokes traction on an active particle: The mechanics and statistical mechanics of a suspension of active particles\nare determined by the traction (force per unit area) on their surfaces. Here we\npresent an exact solution of the direct boundary integral equation for the\ntraction on a spherical active particle in an imposed slow viscous flow. Both\nsingle- and double-layer integral operators can be simultaneously diagonalised\nin a basis of irreducible tensorial spherical harmonics and the solution, thus,\ncan be presented as an infinite number of linear relations between the harmonic\ncoefficients of the traction and the velocity at the boundary of the particle.\nThese generalise Stokes laws for the force and torque. Using these relations we\nobtain simple expressions for physically relevant quantities such as the\nsymmetric-irreducible dipole acting on, or the power dissipated by, an active\nparticle in an arbitrary imposed flow. We further present an explicit\nexpression for the variance of the Brownian contributions to the traction on an\nactive colloid in a thermally fluctuating fluid.",
        "positive": "Programmable collective behavior in dynamically self-assembled mobile\n  microrobotic swarms: Collective control of mobile microrobotic swarms is indispensable for their\npotential high-impact applications in targeted drug delivery, medical\ndiagnostics, parallel micromanipulation, and environmental sensing and\nremediation. Lack of on-board computational and sensing capabilities in current\nmicrorobotic systems necessitates use of physical interactions among individual\nmicrorobots for local physical communication and cooperation. Here, we show\nthat mobile microrobotic swarms with well-defined collective behavior can be\ndesigned by engineering magnetic interactions among individual units.\nMicrorobots, consisting of a linear chain of self-assembled magnetic\nmicroparticles, locomote on surfaces in response to a precessing magnetic\nfield. Control over the direction of precessing magnetic field allows\nengineering attractive and repulsive interactions among microrobots and, thus,\ncollective order with well-defined spatial organization and parallel operation\nover macroscale distances (~1 cm). These microrobotic swarms can be guided\nthrough confined spaces, while preserving microrobot morphology and function.\nThese swarms can further achieve directional transport of large cargoes on\nsurfaces and small cargoes in bulk fluids. Described design approach,\nexploiting physical interactions among individual robots, enables facile and\nrapid formation of self-organized and reconfigurable microrobotic swarms with\nprogrammable collective order."
    },
    {
        "anchor": "Atom optics with rotating Bose-Einstein condensates: The atom optics of Bose-Einstein condensates containing a vortex of\ncirculation one is discussed. We first analyze in detail the reflection of such\na condensate falling on an atomic mirror. In a second part, we consider a\nrotating condensate in the case of attractive interactions. We show that for\nsufficiently large nonlinearity the rotational symmetry of the rotating\ncondensate is broken.",
        "positive": "Unzipping of a double-stranded block copolymer DNA by a periodic force: Using Monte Carlo simulations, we study the hysteresis in unzipping of a\ndouble stranded block copolymer DNA with $-A_n B_n-$ repeat units. Here $A$ and\n$B$ represent two different types of base pairs having two- and three-bonds,\nrespectively, and $2n$ represents the number of such base pairs in a unit. The\nend of the DNA are subjected to a time dependent periodic force with frequency\n($\\omega$) and amplitude ($g_0$) keeping the other end fixed. We find that the\nequilibrium force-temperature phase diagram for the static force is independent\nof the DNA sequence. For the periodic force case, the results are found to be\ndependent on the block copolymer DNA sequence and also on the base pair type on\nwhich the periodic force is acting. We observe hysteresis loops of various\nshapes and sizes and obtain the scaling of loop area both at low and high\nfrequency regimes."
    },
    {
        "anchor": "Determining the nonequilibrium criticality of a Gardner transition via a\n  hybrid study of molecular simulations and machine learning: Apparent critical phenomena, typically indicated by growing correlation\nlengths and dynamical slowing-down, are ubiquitous in non-equilibrium systems\nsuch as supercooled liquids, amorphous solids, active matter and spin glasses.\nIt is often challenging to determine if such observations are related to a true\nsecond-order phase transition as in the equilibrium case, or simply a\ncrossover, and even more so to measure the associated critical exponents. Here,\nwe show that the simulation results of a hard-sphere glass in three dimensions,\nare consistent with the recent theoretical prediction of a Gardner transition,\na continuous non-equilibrium phase transition. Using a hybrid molecular\nsimulation-machine learning approach, we obtain scaling laws for both\nfinite-size and aging effects, and determine the critical exponents that\ntraditional methods fail to estimate. Our study provides a novel approach that\nis useful to understand the nature of glass transitions, and can be generalized\nto analyze other non-equilibrium phase transitions.",
        "positive": "Spontaneous polar and chiral symmetry breaking in ordered fluids --\n  heliconical ferroelectric nematic phases: It is known that the chiral interaction described by Dzyaloshinskii-Moriya\n(DMI) term lead to the plethora of topological structures of magnetic spins,\nsuch as helical or skyrmion phases. Here we present the that analogues\nelectrical DMI can lead to similar structural complexity of electric dipoles in\nsoft matter. We report on a new polar liquid phase in which achiral molecules\nspontaneously form a heliconical structure. The helical pitch is comparable to\nthe wavelength of visible light and unwinds critically at the transition to a\nuniformly polar, ferroelectric nematic phase. Although this new liquid\ncrystalline phase resembles the twist-bend nematic phase, the mechanism of its\nformation is different and is attributed to electrical interactions that cause\nnon-collinear arrangement of electric dipoles, similarly as observed for spins\nin magnetic systems."
    },
    {
        "anchor": "Packing of Compressible Granular Materials: 3D Computer simulations and experiments are employed to study random packings\nof compressible spherical grains under external confining stress. Of particular\ninterest is the rigid ball limit, which we describe as a continuous transition\nin which the applied stress vanishes as (\\phi-\\phi_c)^\\beta, where \\phi is the\n(solid phase) volume density. This transition coincides with the onset of shear\nrigidity. The value of \\phi_c depends, for example, on whether the grains\ninteract via only normal forces (giving rise to random close packings) or by a\ncombination of normal and friction generated transverse forces (producing\nrandom loose packings). In both cases, near the transition, the system's\nresponse is controlled by localized force chains. As the stress increases, we\ncharacterize the system's evolution in terms of (1) the participation number,\n(2) the average force distribution, and (3) visualization techniques.",
        "positive": "Thermodynamic and structural anomalies of the Gaussian-core model in one\n  dimension: We investigated the equilibrium properties of a one-dimensional system of\nclassical particles which interact in pairs through a bounded repulsive\npotential with a Gaussian shape. Notwithstanding the absence of a proper\nfluid-solid phase transition, we found that the system exhibits a complex\nbehaviour, with \"anomalies\" in the density and in the thermodynamic response\nfunctions which closely recall those observed in bulk and confined liquid\nwater. We also discuss the emergence in the cold fluid under compression of an\nunusual structural regime, characterized by density correlations reminiscent of\nthe ordered arrangements found in clustered crystals."
    },
    {
        "anchor": "Foam-like compression behavior of fibrin networks: The rheological properties of fibrin networks have been of long-standing\ninterest. As such there is a wealth of studies of their shear and tensile\nresponses, but their compressive behavior remains unexplored. Here, by\ncharacterization of the network structure with synchronous measurement of the\nfibrin storage and loss moduli at increasing degrees of compression, we show\nthat the compressive behavior of fibrin networks is similar to that of cellular\nsolids. A non-linear stress-strain response of fibrin consists of three\nregimes: 1) an initial linear regime, in which most fibers are straight, 2) a\nplateau regime, in which more and more fibers buckle and collapse, and 3) a\nmarkedly non-linear regime, in which network densification occurs {{by bending\nof buckled fibers}} and inter-fiber contacts. Importantly, the spatially\nnon-uniform network deformation included formation of a moving \"compression\nfront\" along the axis of strain, which segregated the fibrin network into\ncompartments with different fiber densities and structure. The Young's modulus\nof the linear phase depends quadratically on the fibrin volume fraction while\nthat in the densified phase depends cubically on it. The viscoelastic plateau\nregime corresponds to a mixture of these two phases in which the fractions of\nthe two phases change during compression. We model this regime using a\ncontinuum theory of phase transitions and analytically predict the storage and\nloss moduli which are in good agreement with the experimental data. Our work\nshows that fibrin networks are a member of a broad class of natural cellular\nmaterials which includes cancellous bone, wood and cork.",
        "positive": "Monte Carlo simulations of polymers with nearest- and next\n  nearest-neighbor interactions on square and cubic lattices: We study a generalized interacting self-avoiding walk (ISAW) model with\nnearest- and next nearest-neighbor (NN and NNN) interactions on the square and\ncubic lattices. In both dimensions, the phase diagrams show coil and globule\nphases separated by continuous transition lines. Along these lines, we\ncalculate the metric $\\nu_t$, crossover $\\phi_t$ and entropic $\\gamma_t$\nexponents, all of them in good agreement with the exact values of the $\\Theta$\nuniversality class. Therefore, the introduction of NNN interactions does not\nchange the class of the ISAW model, which still exists even for repulsive\nforces. The growth parameters $\\mu_t$ are shown to change monotonically with\ntemperature along the $\\Theta$-lines. In the square lattice, the $\\Theta$-line\nhas an almost linear behavior, which was not found in the cubic one. Although\nthe region of repulsive NNN interactions, with attractive NN ones, leads to\nstiff polymers, no evidence of a transition to a crystalline phase was found."
    },
    {
        "anchor": "Influence of surface interactions on folding and forced unbinding of\n  semiflexible chains: We investigate the folding and forced-unbinding transitions of adsorbed\nsemiflexible polymer chains using theory and simulations. These processes\ndescribe biologically relevant phenomena that include adhesive interactions\nbetween proteins and tethering of receptors to cell walls. The binding\ninterface is modeled as a solid surface and the worm-like chain is used for the\nsemiflexible chain. Using Langevin simulations we examine the ordering kinetics\nof racquet-like and toroidal structures in the presence of attractive\ninteraction between the surface and the polymer chain. For a range of\ninteractions, temperature, and the persistence length l_p we obtained the\nmonomer density distribution n(x) for all the relevant morphologies. The\nsimulated results for n(x) are in good agreement with theory. The formation of\ntoroids on the surface appears to be a first order transition. Chain-surface\ninteraction is probed by subjecting the surface structures to a pulling force\nf. The average extension x as a function of f exhibit sigmoidal profile with\nsharp all-or-none transition at the unfolding f_c which increases for more\nstructured states. Simulated x compare well with the theoretical predictions.\nThe critical force f_c is a function of l_s/l_c for a fixed temperature, where\nl_c, l_s are the length scales that express the strength of the intramolecular\nand chain-surface attraction, respectively. For a fixed l_s, f_c increases as\nl_p decreases.",
        "positive": "Random-Graph Models and Characterization of Granular Networks: Various approaches and measures from network analysis have been applied to\ngranular and particulate networks to gain insights into their structural,\ntransport, failure-propagation and other systems-level properties. In this\narticle, we examine a variety of common network measures and study their\nability to characterize various two-dimensional and three-dimensional spatial\nrandom-graph models and empirical two-dimensional granular networks. We\nidentify network measures that are able to distinguish between physically\nplausible and unphysical spatial network models. Our results also suggest that\nthere are significant differences in the distributions of certain network\nmeasures in two and three dimensions, hinting at important differences that we\nalso expect to arise in experimental granular networks."
    },
    {
        "anchor": "Snapping of Bistable, Prestressed Cylindrical Shells: Bistable shells can reversibly change between two stable configurations with\nvery little energetic input. Understanding what governs the shape and\nsnap-through criteria of these structures is crucial for designing devices that\nutilize instability for functionality. Bistable cylindrical shells fabricated\nby stretching and bonding multiple layers of elastic plates will contain\nresidual stress that will impact the shell's shape and the magnitude of\nstimulus necessary to induce snapping. Using the framework of non-Euclidean\nshell theory, we first predict the mean curvature of a nearly cylindrical shell\nformed by arbitrarily prestretching one layer of a bilayer plate with respect\nto another. Then, beginning with a residually stressed cylinder, we determine\nthe amount of the stimuli needed to trigger the snapping between two\nconfigurations through a combination of numerical simulations and theory. We\ndemonstrate the role of prestress on the snap-through criteria, and highlight\nthe important role that the Gaussian curvature in the boundary layer of the\nshell plays in dictating shell stability.",
        "positive": "Stability Threshold as a Selection Principle for Protein Design: The sensitivity of the native states of protein-like heteropolymers to\nmutations modelled as perturbations in the interaction potential between amino\nacids is studied. The stability threshold against mutations is shown to be zero\nfor random heteropolymers on a lattice in two dimensions, whereas a design\nprocedure modelling evolution produces a non-zero threshold. We introduce an\nevolution-like protein design procedure based on an optimization of the\nstability threshold that is shown to naturally ensure thermodynamic stability\nas well."
    },
    {
        "anchor": "Novel Universality Classes in Ferroelectric Liquid Crystals: Starting from a Langevin formulation of a thermally perturbed nonlinear\nelastic model of the ferroelectric smectic-C$^*$ (SmC${*}$) liquid crystals in\nthe presence of an electric field, this article characterizes the hitherto\nunexplored dynamical phase transition from a thermo-electrically forced\nferroelectric SmC${}^{*}$ phase to a chiral nematic liquid crystalline phase\nand vice versa. The theoretical analysis is based on a combination of dynamic\nrenormalization (DRG) and numerical simulation of the emergent model. While the\nDRG architecture predicts a generic transition to the Kardar-Parisi-Zhang (KPZ)\nuniversality class at dynamic equilibrium, in agreement with recent\nexperiments, the numerical simulations of the model show simultaneous existence\nof two phases, one a \"subdiffusive\" (SD) phase characterized by a dynamical\nexponent value of 1, and the other a KPZ phase, characterized by a dynamical\nexponent value of 1.5. The SD phase flows over to the KPZ phase with increased\nexternal forcing, offering a new universality paradigm, hitherto unexplored in\nthe context of ferroelectric liquid crystals.",
        "positive": "Revisiting the Hanbury Brown-Twiss Setup for Phase Fluctuating Bose\n  Gases: The Hanbury Brown-Twiss experiment has proved to be an effective means of\nmeasuring two-point correlation function of identical particles. We analyze\nexperimental observation of stripes formation of a phase fluctuating\nBose-Einstein condensates in a highly elongated 3D traps [Dettmer {\\em et al.},\nPhys. Rev. Lett. {\\bf 87}, 160406 (2001)] by means of axial two-point\ncorrelation functions. We also predict that the stripes are present in quasi-1D\nBose gas in the mean-field as well as in the hard-core bosons regimes. These\nstripes can be realized by measuring the axial two-point correlation functions\nby using the Bragg interferometric method which is similar to the original\nHanbury Brown and Twiss experimental setup."
    },
    {
        "anchor": "Dislocation Dynamics in an Anisotropic Stripe Pattern: The dynamics of dislocations confined to grain boundaries in a striped system\nare studied using electroconvection in the nematic liquid crystal N4. In\nelectroconvection, a striped pattern of convection rolls forms for sufficiently\nhigh driving voltages. We consider the case of a rapid change in the voltage\nthat takes the system from a uniform state to a state consisting of striped\ndomains with two different wavevectors. The domains are separated by domain\nwalls along one axis and a grain boundary of dislocations in the perpendicular\ndirection. The pattern evolves through dislocation motion parallel to the\ndomain walls. We report on features of the dislocation dynamics. The kinetics\nof the domain motion are quantified using three measures: dislocation density,\naverage domain wall length, and the total domain wall length per area. All\nthree quantities exhibit behavior consistent with power law evolution in time,\nwith the defect density decaying as $t^{-1/3}$, the average domain wall length\ngrowing as $t^{1/3}$, and the total domain wall length decaying as $t^{-1/5}$.\nThe two different exponents are indicative of the anisotropic growth of domains\nin the system.",
        "positive": "Structural Polymorphism of the Cytoskeleton: A Model of Linker-Assisted\n  Filament Aggregation: The phase behavior of charged rods in the presence of inter-rod linkers is\nstudied theoretically as a model for the equilibrium behavior underlying the\norganization of actin filaments by linker proteins in the cytoskeleton. The\npresence of linkers in the solution modifies the effective inter-rod\ninteraction and can lead to inter-filament attraction. Depending on the\nsystem's composition and physical properties such as linker binding energies,\nfilaments will either orient perpendicular or parallel to each other, leading\nto network-like or bundled structures. We show that such a system can have one\nof three generic phase diagrams, one dominated by bundles, another by networks,\nand the third containing both bundle and network-like phases. The first two\ndiagrams can be found over a wide range of interaction energies, while the\nthird occurs only for a narrow range. These results provide theoretical\nunderstanding of the classification of linker proteins as bundling proteins or\ncrosslinking proteins. In addition, they suggest possible mechanisms by which\nthe cell may control cytoskeletal morphology."
    },
    {
        "anchor": "Gravitational effect on the advancing and receding angle of a 2D\n  Cassie-Baxter droplet on a textured surface: Advancing and receding angles are physical quantities frequently measured to\ncharacterize the wetting properties of a rough surface. Thermodynamically, the\nadvancing and receding angles are often interpreted as the maximum and minimum\ncontact angles that can be formed by a droplet without losing its stability.\nDespite intensive research on wetting of rough surfaces, the gravitational\neffect on these angles has been overlooked because most studies have considered\ndroplets smaller than the capillary length. In this study, however, by\ncombining theoretical and numerical modeling, we show that the shape of a\ndroplet smaller than the capillary length can be substantially modified by\ngravity under advancing and receding conditions. First, based on the Laplace\npressure equation, we predict the shape of a two-dimensional Cassie-Baxter\ndroplet on a textured surface with gravity at each pinning point. Then the\nstability of the droplet is tested by examining the interference between the\nliquid surface and neighboring pillars as well as analyzing the free energy\nchange upon depinning. Interestingly, it turns out that the apparent contact\nangles under advancing and receding conditions are not affected by gravity,\nwhile the overall shape of a droplet and the position of the pinning point is\naffected by gravity. In addition, the advancing and receding of the droplet\nwith continuously increasing or decreasing volume is analyzed, and it is showed\nthat the gravitational effect plays a key role on the movement of the droplet\ntip. Finally, the theoretical predictions were validated against line-tension\nbased front tracking modeling that seamlessly captures the attachment and\ndetachment between the liquid surface and the solid substrate.",
        "positive": "Polyelectrolyte stars in planar confinement: We employ monomer-resolved Molecular Dynamics simulations and theoretical\nconsiderations to analyze the conformations of multiarm polyelectrolyte stars\nclose to planar, uncharged walls. We identify three mechanisms that contribute\nto the emergence of a repulsive star-wall force, namely: the confinement of the\ncounterions that are trapped in the star interior, the increase in\nelectrostatic energy due to confinement as well as a novel mechanism arising\nfrom the compression of the stiff polyelectrolyte rods approaching the wall.\nThe latter is not present in the case of interaction between two\npolyelectrolyte stars and is a direct consequence of the impenetrable character\nof the planar wall."
    },
    {
        "anchor": "Odd-odd Magnetic Interaction and Spontaneous Ortho-para Transitions in\n  Molecule and Molecular Hydrogen Ion: Spontaneous nuclear ortho-para transitions are shown to be possible in\nhydrogen molecule and molecular ion as due to hyperfine interaction odd-odd\nrelative to the space or spin nuclear coordinate permutations. A part of this\ninteraction inversely proportional to the first power of nuclear mass is found\nfor hydrogen molecular ion.",
        "positive": "Condensed states of a semiflexible copolymer in poor solvent: Figures of\n  eight and discrete size torii: We examine the condensed states of a simple semiflexible copolymer in which\nthere are two monomer types that are immiscible with each other and with the\nsolvent. Although this is similar to the well known problem of collapse for a\nsemiflexible homopolymer we find that it gives rise to a much richer variety of\ncondensed states. We predict the existence of these states using simple\nanalytic arguments and also observe them directly using Brownian dynamics\nsimulations."
    },
    {
        "anchor": "Effective equilibrium states in the colored-noise model for active\n  matter II. A unified framework for phase equilibria, structure and mechanical\n  properties: Active particles driven by colored noise can be approximately mapped onto a\nsystem that obeys detailed balance. The effective interactions which can be\nderived for such a system allow to describe the structure and phase behavior of\nthe active fluid by means of an effective free energy. In this paper we explain\nwhy the related thermodynamic results for pressure and interfacial tension do\nnot represent the results one would measure mechanically. We derive a dynamical\ndensity functional theory, which in the steady state simultaneously validates\nthe use of effective interactions and provides access to mechanical quantities.\nOur calculations suggest that in the colored-noise model the mechanical\npressure in coexisting phases might be unequal and the interfacial tension can\nbecome negative.",
        "positive": "Free Solution Electrophoresis of Homopolyelectrolytes: We investigate the behavior of single polyelectrolytes in multivalent salt\nsolutions under the action of electric fields through computer simulations. The\nchain is unfolded in a strong electric field and aligned parallel to the field\ndirection, and the chain size shows a sigmoidal transition. The unfolding\nelectric field $E^*$ depends on the salt concentration and scales as $V^{-1/2}$\nwith $V$ being the ellipsoidal volume occupied by the chain. The magnitude of\nthe electrophoretic mobility of chain drastically increases during the\nunfolding. The fact that $E^*$ depends on the chain length provides a plausible\nmechanism to separate long charged homopolymers by size in free solution\nelectrophoresis via the unfolding transition of globule polyelectrolytes\ncondensed by multivalent salt."
    },
    {
        "anchor": "Self-induced polar order of active Brownian particles in a harmonic trap: Hydrodynamically interacting active particles in an external harmonic\npotential form a self-assembled fluid pump at large enough P\\'eclet numbers.\nHere, we give a quantitative criterion for the formation of the pump and show\nthat particle orientations align in the self-induced flow field in surprising\nanalogy to ferromagnetic order where the active P\\'eclet number plays the role\nof inverse temperature. The particle orientations follow a Boltzmann\ndistribution $\\Phi(\\mathbf{p}) \\sim \\exp(A p_z)$ where the ordering mean field\n$A$ scales with active P\\'eclet number and polar order parameter. The mean flow\nfield in which the particles' swimming directions align corresponds to a\nregularized stokeslet with strength proportional to swimming speed. Analytic\nmean-field results are compared with results from Brownian dynamics simulations\nwith hydrodynamic interactions included and are found to capture the\nself-induced alignment very well.",
        "positive": "Equilibrium Bundle Size of Rodlike Polyelectrolytes with\n  Counterion-Induced Attractive Interactions: Multivalent counterions can induce an effective attraction between\nlike-charged rodlike polyelectrolytes, leading to the formation of\npolelectrolyte bundles. In this paper, we calculate the equilibrium bundle size\nusing a simple model in which the attraction between polyelectrolytes (assumed\nto be pairwise additive) is treated phenomenologically. If the counterions are\npoint-like, they almost completely neutralize the charge of the bundle, and the\nequilibrium bundle size diverges. When the counterions are large, however,\nsteric and short-range electrostatic interactions prevent charge neutralization\nof the bundle, thus forcing the equilibrium bundle size to be finite. We also\nconsider the possibility that increasing the number of nearest neighbors for\neach rod in the bundle frustrates the attractive interaction between the rods.\nSuch a frustration leads to the formation of finite size bundles as well, even\nwhen the counterions are small."
    },
    {
        "anchor": "Critical numbers of attractive Bose-condensed atoms in asymmetric traps: The recent Bose-Einstein condensation of ultracold atoms with attractive\ninteractions led us to consider the novel possibility to probe the stability of\nits ground state in arbitrary three-dimensional harmonic traps. We performed a\nquantitative analysis of the critical number of atoms through a full numerical\nsolution of the mean field Gross-Pitaevskii equation. Characteristic limits are\nobtained for reductions from three to two and one dimensions, in perfect\ncylindrical symmetries as well as in deformed ones.",
        "positive": "Transfer coefficients for the Gibbs surface in a two-phase mixture in\n  the non-equilibrium square gradient model: In this paper we calculate the transfer coefficients for evaporation and\ncondensation of mixtures. We use the continuous profiles of various\nthermodynamic quantities through the interface, obtained in our previous works\nusing the square gradient model. Furthermore we introduce the Gibbs surface and\nobtain the excess entropy production for a surface. Following the traditional\nnon-equilibrium thermodynamic approach we introduce the surface transfer\ncoefficients which we are able to determine from the continuous solution. The\nknowledge of these coefficients is important for many industrial applications\nwhich involve transport through a surface, such as for instance distillation.\nIn our approach the values of the local resistivities in the liquid and the\nvapor phases are chosen on the basis of experimental values. In the interfacial\nregion there are small peaks in these resistivities. Three amplitudes control\nthe magnitude of these peaks. Possible values of these amplitudes are found by\nmatching the diagonal transfer coefficients to values predicted by kinetic\ntheory. Using these amplitudes we find that the value of the cross\nresistivities is 1-2 orders of magnitude higher then the one from kinetic\ntheory. The results of both kinetic theory and molecular dynamics simulations\nsupport the existence of small peaks in the local resistivities in the\ninterfacial region. The square gradient approach gives an independent way to\ndetermine the transfer coefficients for surfaces. The results indicate that\nkinetic theory underestimates the interfacial transfer coefficients in real\nfluids."
    },
    {
        "anchor": "The effect of elastic walls on suspension flow: We study suspensions of rigid particles in a plane Couette flow with\ndeformable elastic walls. We find that, in the limit of vanishing inertia, the\nelastic walls induce shear thinning of the suspension flow such that the\neffective viscosity decreases as the wall deformability increases. This\nshear-thinning behavior originates from the interactions between rigid\nparticles, soft wall and carrier fluid; an asymmetric wall deformation induces\na net lift force acting on the particles which therefore migrate towards the\nbulk of the channel. Based on our observations, we provide a closure for the\nsuspension viscosity which can be used to model the rheology of suspensions\nwith arbitrary volume fraction in elastic channels.",
        "positive": "Comments on \"Evidence for Nuclear Emissions During Acoustic Cavitation\"\n  by R.P. Taleyarkhan et al., Science volume 295,p.1868, March 8, 2002: In a paper recently published in Science, Taleyarkhan et al. claimed to\nobserve fusion from acoustic cavitation and the associated phenomenon of\nsonoluminescence. Although, this is a worthwhile line of investigation we\nexplain why, in our opinion, their data neither proves nor disproves this\npossibility."
    },
    {
        "anchor": "Magnetic Field Tomography: Neutral atoms may be trapped via the interaction of their magnetic dipole\nmoment with magnetic field gradients. One of the possible schemes is the\ncloverleaf trap. It is often desirable to have at hand a fast and precise\ntechnique for measuring the magnetic field distribution. We introduce a novel\ndiagnostic tool for instantaneous imaging the equipotential lines of a magnetic\nfield within a region of space (the vacuum recipient) that is not accessible to\nmassive probes. Our technique is based on spatially resolved observation of the\nfluorescence emitted by a hot beam of sodium atoms crossing a thin slice of\nresonant laser light within the magnetic field region to be investigated. The\ninhomogeneous magnetic field spatially modulates the resonance condition\nbetween the Zeeman-shifted hyperfine sublevels and the laser light and\ntherefore the amount of scattered photons. We demonstrate this technique by\nmapping the field of our cloverleaf trap in three dimensions under various\nconditions.",
        "positive": "Confined granular packings: structure, stress, and forces: The structure and stresses of static granular packs in cylindrical containers\nare studied using large-scale discrete element molecular dynamics simulations\nin three dimensions. We generate packings by both pouring and sedimentation and\nexamine how the final state depends on the method of construction. The vertical\nstress becomes depth-independent for deep piles and we compare these stress\ndepth-profiles to the classical Janssen theory. The majority of the tangential\nforces for particle-wall contacts are found to be close to the Coulomb failure\ncriterion, in agreement with the theory of Janssen, while particle-particle\ncontacts in the bulk are far from the Coulomb criterion. In addition, we show\nthat a linear hydrostatic-like region at the top of the packings unexplained by\nthe Janssen theory arises because most of the particle-wall tangential forces\nin this region are far from the Coulomb yield criterion. The distributions of\nparticle-particle and particle-wall contact forces $P(f)$ exhibit\nexponential-like decay at large forces in agreement with previous studies."
    },
    {
        "anchor": "Digital instability of a confined elastic meniscus: Thin soft elastic layers serving as joints between relatively rigid bodies\nmay function as sealants, thermal, electrical, or mechanical insulators,\nbearings, or adhesives. When such a joint is stressed, even though perfect\nadhesion is maintained, the exposed free meniscus in the thin elastic layer\nbecomes unstable, leading to the formation of spatially periodic digits of air\nthat invade the elastic layer, reminiscent of viscous fingering in a thin fluid\nlayer. How- ever, the elastic instability is reversible and rate-independent,\ndis- appearing when the joint is unstressed. We use theory, experiments, and\nnumerical simulations to show that the transition to the digital state is\nsudden (first-order), the wavelength and amplitude of the fingers are\nproportional to the thickness of the elastic layer, and the required separation\nto trigger the instability is inversely proportional to the in-plane dimension\nof the layer. Our study reveals the energetic origin of this instability and\nhas implications for the strength of polymeric adhesives; it also suggests a\nmethod for patterning thin films reversibly with any arrangement of localized\nfingers in a digital elastic memory, which we confirm experimentally.",
        "positive": "Improving the prediction of glassy dynamics by pinpointing the local\n  cage: The relationship between structure and dynamics in glassy fluids remains an\nintriguing open question. Recent work has shown impressive advances in our\nability to predict local dynamics using structural features, most notably due\nto the use of advanced machine learning techniques. Here we explore whether a\nsimple linear regression algorithm combined with intelligently chosen\nstructural order parameters can reach the accuracy of the current, most\nadvanced machine learning approaches for predicting dynamic propensity. To do\nthis we introduce a method to pinpoint the cage state of the initial\nconfiguration -- i.e. the configuration consisting of the average particle\npositions when particle rearrangement is forbidden. We find that, in comparison\nto both the initial state and the inherent state, the structure of the cage\nstate is highly predictive of the long-time dynamics of the system. Moreover,\nby combining the cage state information with the initial state, we are able to\npredict dynamic propensities with unprecedentedly high accuracy over a broad\nregime of time scales, including the caging regime."
    },
    {
        "anchor": "Aggregation of a macromolecule in a nano cube: We model a macromolecule as an infinitely long Gaussian semi-flexible polymer\nchain and the conformations of the chain were realized in the nano cube using a\ncubic lattice. A modified version of the recursion relations is used to\ncalculate the grand canonical partition function of the chain to investigate\ndistinct thermo-dynamical properties of the nano polymer aggregate than\ncorresponding bulk behaviour of the macromolecule. Our analytical estimates on\nthe thermodynamical properties of the macromolecule clearly show that the nano\naggregate of the polymer chain has interesting and distinct conformational\nstatistics than its corresponding bulk state, and the method described in the\npresent report can be easily extend to investigate the thermodynamics of the\nselfavoiding polymer chain in the nano dimensions.",
        "positive": "Free-energy barrier of filling a spherical cavity in the presence of\n  line tension: Implication to the energy barrier between the Cassie and Wenzel\n  state on a superhydrophobic surface with spherical cavities: The free-energy barrier of filling a spherical cavity having an inner wall of\nvarious wettabiities is studied. The morphology and free energy of a\nlens-shaped droplet are determined from the minimum of the free energy. The\neffect of line tension on the free energy is also studied. Then, the\nequilibrium contact angle of the droplet is determined from the generalized\nYoung's equation. By increasing the droplet volume within the spherical cavity,\nthe droplet morphology changes from spherical with an equilibrium contact angle\nof $180^{\\circ}$ to a lens with a convex meniscus, where the morphological\ncomplete drying transition occurs. By further increasing the droplet volume,\nthe meniscus changes from convex to concave. Then, the lens-shaped droplet with\nconcave meniscus spreads over the whole inner wall resulting in an equilibrium\ncontact angle of $0^{\\circ}$ to leave a spherical bubble, where the\nmorphological complete wetting transition occurs. Finally, the whole cavity is\nfilled with liquid. The free energy shows a barrier from complete drying to\ncomplete wetting as a function of droplet volume, which corresponds to the\nenergy barrier between the Cassie and Wenzel state of the superhydrophobic\nsurface with spherical cavities. The free-energy maximum occurs when the\nmeniscus of the droplet becomes flat and it is given by an analytic formula.\nThe effect of line tension is expressed by the scaled line tension, and this\neffect is largest at the free-energy maximum. The positive line tension\nincreases the free-energy maximum, which thus, increases the stability of the\nCassie superhydrophobic state, whereas the negative line tension destabilizes\nthe superhydrophobic state."
    },
    {
        "anchor": "Controlling local order of athermal self-propelled particles: We consider a model of self-propelled dynamics for athermal active particles,\nwhere the non-equilibrium active forces are modelled by a Ornstein-Uhlenbeck\nprocess. In the limit of no-driving force, the model reduces to the passive,\nBrownian dynamics of an atomistic glass forming fluid, the Wahnstr\\\"om binary\nmixture. The Wahnstr\\\"om mixture is known to show strong correlations between\nthe emergence of slow dynamics and the formation of locally favoured structures\nbased on icosahedra. Here, we study how the non-equilibrium forces affect the\nlocal structure of the system, and find that these strongly promote icosahedral\norder. The phases rich in local icosahedral order correspond to configurations\nof very low potential energy, suggesting that the non-equilibrium dynamics in\nthe self propelled model can be effectively exploited to explore the potential\nenergy surface of the binary mixture and have access to states that are\ndifficult to attain using passive dynamics.",
        "positive": "Role of curvature and domain shape on Turing patterns: We consider pattern formation using reaction-diffusion equation on various\nnon-uniformly curved surfaces. We explore how, in general, curvature and, in\nparticular the domain shape would affect the pattern formation in these\ngeometries. As examples, we study stripe and spot patterns on a torus, and on\nan ellipsoid. Our results show that the curvature and domain shape can control\nthe orientation of stripe pattern as well as the size and number of spots. Our\nresults also indicate that by controlling the curvature and shape, one can\ndrive the chemicals to a preferred region. Specifically on a torus, curvature\nand shape can guide the chemicals more on to outer side than inner side. This\nresult may prove important in the studies of self-organization of molecules in\nbiological membranes."
    },
    {
        "anchor": "Effective equilibrium states in mixtures of active particles driven by\n  colored noise: We consider the steady-state behavior of pairs of active particles having\ndifferent persistence times and diffusivities. To this purpose we employ the\nactive Ornstein-Uhlenbeck model, where the particles are driven by colored\nnoises with exponential correlation functions whose intensities and correlation\ntimes vary from species to species. By extending Fox's theory to many\ncomponents, we derive by functional calculus an approximate Fokker-Planck\nequation for the configurational distribution function of the system. After\nillustrating the predicted distribution in the solvable case of two particles\ninteracting via a harmonic potential, we consider systems of particles\nrepelling through inverse power laws potentials. We compare the analytic\npredictions to computer simulations for such soft-repulsive interactions in one\ndimension, and show that at linear order in the persistence times the theory is\nsatisfactory. This work provides the toolbox to qualitatively describe\nmany-body phenomena, such as demixing and depletion, by means of effective pair\npotentials.",
        "positive": "Concentration Dependen Sedimentation of Collidal Rods: In the first part of this paper, an approximate theory is developed for the\nleading order concentration dependence of the sedimentation coefficient for\nrod-like colloids/polymers/macromolecules. To first order in volume fraction\n$\\phi$ of rods, the sedimentation coefficient is written as $1+\\alpha \\phi$.\nFor large aspect ratio L/D (L is the rod length, D it's thickness) $\\alpha$ is\nfound to very like $\\propto (\\frac{L}{D})^2/\\log (\\frac{L}{D})$. This\ntheoretical prediction is compared to experimental results. In the second part,\nexperiments on {\\it fd}-virus are described, both in the isotropic and nematic\nphase. First order in concentration results for this very long and thin\n(semi-flexible) rod are in agreement with the above theoretical prediction.\nSedimentation profiles for the nematic phase show two sedimentation fronts.\nThis result indicates that the nematic phase becomes unstable with the respect\nto isotropic phase during sedimentation."
    },
    {
        "anchor": "Rigidity and auxeticity transitions in networks with strong bond-bending\n  interactions: A widely-studied model for gels or biopolymeric fibrous materials are\nnetworks with central force interactions, such as Hookean springs. Less\ncommonly studied are materials whose mechanics are dominated by non-central\nforce interactions such as bond-bending potentials. Inspired by recent\nexperimental advancements in designing colloidal gels with tunable\ninteractions, we study the micro- and macroscopic elasticity of two-dimensional\nplanar graphs with strong bond bending potentials, in addition to weak central\nforces. We introduce a theoretical framework that allows us to directly\ninvestigate the limit in which the ratio of characteristic central-force to\nbending stiffnesses vanishes. In this limit we show that a generic isostatic\npoint exists at $z_c=4$, coinciding with the isostatic point of frames with\ncentral force interactions in two dimensions. We further demonstrate the\nemergence of a stiffening transition when the coordination is increased towards\nthe isostatic point, which shares similarities with the strain-induced\nstiffening transition observed in biopolymeric fibrous materials, and coincides\nwith an auxeticity transition above which the material's Poisson's ratio\napproaches -1 when bond-bending interactions dominate.",
        "positive": "Onset of Convection in a Very Compressible Fluid : The Transient Toward\n  Steady State: We analyze the time profile $\\Delta T(t)$ of the temperature difference,\nmeasured across a very compressible supercritical $^3$He fluid layer in its\nconvective state. The experiments were done along the critical isochore in a\nRayleigh-B\\'{e}nard cell after starting the vertical constant heat flow $q$.\nFor $q$ sufficiently well above that needed for the convection onset, the\ntransient $\\Delta T(t)$ for a given $\\epsilon\\equiv(T-T_c)/T_c$, with $T_c$ =\n3.318K, shows a damped oscillatory profile with period $t_{osc}$ modulating a\nsmooth base profile. The smooth profile forms the exponential tail of the\ntransient which tends to the steady-state $\\Delta T(\\infty)$ with a time\nconstant $\\tau_{tail}$. The scaled times $t_{osc}/t_D$ and $\\tau_{tail}/t_D$\nfrom all the data could be collapsed onto two curves as a function of the\nRayleigh number over $\\sim$ 3.5 decades. Here $t_D$ is the characteristic\nthermal diffusion time. Furthermore comparisons are made between measurements\nof a third characteristic time $t_m$ between the first peak and the first\nminimum in the $\\Delta T(t)$ profile and its estimation by Onuki et al. Also\ncomparisons are made between the observed oscillations and the 2D simulations\nby Onuki et al. and by Amiroudine and Zappoli. For $\\epsilon < 9\\times 10^{-3}$\nthe experiments show a crossover to a different transient regime. This new\nregime, which we briefly describe, is not understood at present."
    },
    {
        "anchor": "Multi-objective optimization for targeted self-assembly among competing\n  polymorphs: While inverse approaches for designing crystalline materials typically focus\non the thermodynamic stability of a target polymorph, the outcome of a\nself-assembly process is often controlled by kinetic pathways. A prototypical\nexample is the design of an isotropic pair potential to guide the self-assembly\nof a two-dimensional honeycomb lattice, which is a challenging problem due to\nthe existence of competing crystal polymorphs. Here we present a\nmachine-learning-guided approach to explore potentials that maximize both the\nthermodynamic stability and kinetic accessibility of the honeycomb polymorph.\nOptimal pair potentials exist along a Pareto front, indicating a trade-off\nbetween these objectives. We show that this trade-off is density-dependent and\narises from a competition between crystal polymorphs: Kinetically optimal\npotentials that favor the honeycomb polymorph on short timescales tend to\nstabilize a triangular polymorph at long times. Finally, we explore the\nfundamental limits of optimization algorithms based on ensembles of short\ntrajectories, which can find potentials close to the kinetically optimal region\nof the Pareto Front. Our work reveals fundamental trade-offs between\ncrystallization speed and accuracy in the presence of competing polymorphs and\nsuggests guiding principles for the development of materials design algorithms\nthat optimize for kinetic accessibility.",
        "positive": "Non-affine lattice dynamics of defective fcc crystals: The mechanical, thermal and vibrational properties of defective crystals are\nimportant in many different contexts, from metallurgy and solid-state physics\nto, more recently, soft matter and colloidal physics. Here we study two\ndifferent models of disordered fcc crystal lattices, with randomly-removed\nbonds and with vacancies, respectively, within the framework of non-affine\nlattice dynamics. We find that both systems feature the same scaling of the\nshear modulus with the newly defined inversion-symmetry breaking (ISB)\nparameter, which shows that local inversion-symmetry breaking around defects is\nthe universal root source of the non-affine softening of the shear modulus.\nThis finding allows us to derive analytical relations for the non-affine\n(zero-frequency) shear modulus as a function of vacancy concentration in\nexcellent agreement with numerical simulations. Nevertheless, due to the\ndifferent microstructural disorder, the spatial fluctuations of the local ISB\nparameter are different in the vacancy and bond-depleted case. The vacancy fcc\nexhibits comparatively a more heterogenous microstructural disorder (due to the\nbroader distribution of coordination number $Z$), which is reflected in a\ndifferent scaling relation between boson peak frequency in the DOS and the\naverage $\\bar{Z}$. These differences are less important at low vacancy\nconcentrations, where the numerical DOS of the vacancy fcc can be well\ndescribed theoretically by coherent-potential approximation, presented here for\nthe bond-depleted fcc lattice in 3d."
    },
    {
        "anchor": "Growth kinetics of circular liquid domains on vesicles by\n  diffusion-controlled coalescence: Motivated by recent experiments on multi-component membranes, the growth\nkinetics of domains on vesicles is theoretically studied. It is known that the\nsteady-state rate of coalescence cannot be obtained by taking the long-time\nlimit of the coalescence rate when the membrane is regarded as an infinite\ntwo-dimensional (2D) system. The steady-state rate of coalescence is obtained\nby explicitly taking into account the spherical vesicle shape. Using the\nexpression of the 2D diffusion coefficient obtained in the limit of small\ndomain size, an analytical expression for the domain growth kinetics is\nobtained when the circular shape is always maintained. For large domains, the\ngrowth kinetics is discussed by investigating the size dependence of the\ncoalescence rate using the expression for the diffusion coefficient of\narbitrary domain size.",
        "positive": "Structural and thermodynamic properties of fluids whose molecules\n  interact via one-, two-, and three-step potentials: The structural and thermodynamic properties of fluids whose molecules\ninteract via potentials with a hard-core plus a square well, a square shoulder,\nand a second square well, are considered. Those properties are derived by using\na (semi-analytical) rational-function approximation method as a particular case\nof the more general formulation provided earlier involving potentials with a\nhard-core plus $n$ piecewise constant sections. Comparison of the results with\nrecent simulation data confirms the usefulness of the approach."
    },
    {
        "anchor": "General scaling relations for locomotion in granular media: We derive a general dimensionless form for granular locomotion, which is\nvalidated in experiments and Discrete Element Method (DEM) simulations. The\nform instructs how to scale size, mass, and driving parameters in order to\nrelate dynamic behaviors of different locomotors in the same granular media.\nThe scaling can be derived by assuming intrusion forces arise from Resistive\nForce Theory (RFT) or equivalently by assuming the granular material behaves as\na continuum obeying a frictional yield criterion. The scalings are\nexperimentally confirmed using pairs of wheels of various shapes and sizes\nunder many driving conditions in a common sand bed. We discuss why the two\nmodels provide such a robust set of scaling laws even though they neglect a\nnumber of the complexities of granular rheology. Motivated by potential\nextra-planetary applications, the dimensionless form also implies a way to\npredict wheel performance in one ambient gravity based on tests in a different\nambient gravity. We confirm this using DEM simulations, which show that scaling\nrelations are satisfied over an array of driving modes even when gravity\ndiffers between scaled tests.",
        "positive": "Jammed packings of 3D superellipsoids with tunable packing fraction,\n  contact number, and ordering: We carry out numerical studies of static packings of frictionless\nsuperellipsoidal particles in three spatial dimensions. We consider more than\n$200$ different particle shapes by varying the three shape parameters that\ndefine superellipsoids. We characterize the structural and mechanical\nproperties of both disordered and ordered packings using two packing-generation\nprotocols. We perform athermal quasi-static compression simulations starting\nfrom either random, dilute configurations (Protocol 1) or thermalized, dense\nconfigurations (protocol $2$), which allows us to tune the orientational order\nof the packings. In general, we find that the contact numbers at jamming onset\nfor superellipsoid packings are hypostatic, with $z_J < z_{\\rm iso}$, where\n$z_{\\rm iso} = 2d_f$ and $d_f = 5$ or $6$ depending on whether the particles\nare axi-symmetric or not. Over the full range of orientational order, we find\nthat the number of quartic modes of the dynamical matrix for the packings\nalways matches the number of missing contacts relative to the isostatic value.\nThis result suggests that there are no mechanically redundant contacts for\nordered, yet hypostatic packings of superellipsoidal particles. Additionally,\nwe find that the packing fraction at jamming onset for disordered packings of\nsuperellipsoidal particles can be collapsed using two particle shape\nparameters, e.g. the asphericity $\\mathcal{A}$ and reduced aspect ratio $\\beta$\nof the particles."
    },
    {
        "anchor": "Anomalous Critical Slowdown at a First Order Phase Transition in Single\n  Polymer Chains: Using Brownian Dynamics, we study the dynamical behavior of a polymer grafted\nonto an adhesive surface close to the mechanically induced\nadsorption-stretching transition. Even though the transition is first order,\n(in the infinite chain length limit, the stretching degree of the chain jumps\ndiscontinuously), the characteristic relaxation time is found to grow according\nto a power law as the transition point is approached. We present a dynamic\neffective interface model which reproduces these observations and provides an\nexcellent quantitaive description of the simulations data. The generic nature\nof the theoretical model suggests that the unconventional mixing of features\nthat are characteristic for first-order transitions (a jump in an order\nparameter) and features that are characteristic of critical points (anomalous\nslowdown) may be a common phenomenon in force-driven phase transitions of\nmacromolecules.",
        "positive": "Wrinkling of Random and Regular Semiflexible Polymer Networks: We investigate wrinkling of two-dimensional random and triangular\nsemiflexible polymer networks under shear. Both types of semiflexible networks\nexhibit wrinkling above a small critical shear angle, which scales with an\nexponent of the bending modulus between 1.9 and 2.0. Random networks exhibit\nhysteresis at the wrinkling threshold. Wrinkling lowers the total elastic\nenergy by up to 20% and strongly affects the elastic properties of all\nsemiflexible networks such as the crossover between bending and stretching\ndominated behavior. In random networks, we also find evidence for metastable\nwrinkled configurations. While the disordered microstructure of random networks\naffects the scaling behavior of wrinkle amplitudes, it has little effect on\nwrinkle wavelength. Therefore, wrinkles represent a robust,\nmicrostructure-independent assay of shear strain or elastic properties."
    },
    {
        "anchor": "Shape diagram of vesicles in Poiseuille flow: Soft bodies flowing in a channel often exhibit parachute-like shapes usually\nattributed to an increase of hydrodynamic constraint (viscous stress and/or\nconfinement). We show that the presence of a fluid membrane leads to the\nreverse phenomenon and build a phase diagram of shapes --- which are classified\nas bullet, croissant and parachute --- in channels of varying aspect ratio.\nUnexpectedly, shapes are relatively wider in the narrowest direction of the\nchannel. We highlight the role of flow patterns on the membrane in this\nresponse to the asymmetry of stress distribution.",
        "positive": "Buckling transition of nematic gels in confined geometry: A spontaneous buckling transition in thin layers of monodomain nematic liquid\ncrystalline gel was observed by polarized light microscopy. The coupling\nbetween the orientational ordering of liquid crystalline solvent and the\ntranslational ordering of crosslinked polymer backbones inside the nematic gel\ncontributes to such buckling transition. As the nematic mesogens become more\nordered when the gel is cooled down from a higher gelation temperature, the\npolymeric backbones tend to elongate along the direction parallel to the\nnematic director, which is perpendicular to the rigid glass surfaces in the\nexperimental setup. The shape change of such confined gel sample lead to the\nspontaneous buckling of polymeric network and the spatial modulation of nematic\nliquid crystalline director, which is observed as the stripe patterns. The\ninstability analysis was used to explain such transitions, and the relationship\nbetween the critical field, stripe's wavelength and temperature can be\nexplained qualitatively by the rubber elasticity theory for liquid crystalline\ngels."
    },
    {
        "anchor": "Interactions Between Charged Rods Near Salty Surfaces: Using both theoretical modeling and computer simulations we study a model\nsystem for DNA interactions in the vicinity of charged membranes. We focus on\nthe polarization of the mobile charges in the membranes due to the nearby\ncharged rods (DNA) and the resulting screening of their fields and inter-rod\ninteractions. We find, both within a Debye-Huckel model and in Brownian\ndynamics simulations, that the confinement of the mobile charges to the surface\nleads to a qualitative reduction in their ability to screen the charged rods to\nthe degree that the fields and resulting interactions are not finite-ranged as\nin systems including a bulk salt concentration, but rather decay algebraically\nand the screening effect is more like an effective increase in the multipole\nmoment of the charged rod.",
        "positive": "Shear localisation with 2D Viscous Froth and its relation to the\n  Continuum Model: Simulations of monodisperse and polydisperse ($\\mu_2(A)=0.13\\pm0.002$) 2D\nfoam samples undergoing simple shear are performed using the 2D Viscous Froth\n(VF) Model. These simulations clearly demonstrate shear localisation. The\ndependence of localisation length on the product $\\lambda V$ (shearing velocity\n$V$ times external wall friction coefficient $\\lambda$) is examined and is\nshown to agree qualitatively with other published experimental data. A wide\nrange of localisation lengths is found at low $\\lambda V$, an effect which is\nattributed to the existence of distinct yield and limit stresses. The general\nContinuum Model is extended to incorporate such an effect and its parameters\nare subsequently related to those of the VF Model. A Herschel-Bulkley exponent\nof $a=0.3$ is shown to accurately describe the observed behaviour. The\nlocalisation length is found to be independent of $\\lambda V$ for monodisperse\nfoam samples."
    },
    {
        "anchor": "Curvature Dependence of Surface Free Energy of Liquid Drops and Bubbles:\n  A Simulation Study: We study the excess free energy due to phase coexistence of fluids by Monte\nCarlo simulations using successive umbrella sampling in finite LxLxL boxes with\nperiodic boundary conditions. Both the vapor-liquid phase coexistence of a\nsimple Lennard-Jones fluid and the coexistence between A-rich and B-rich phases\nof a symmetric binary (AB) Lennard-Jones mixture are studied, varying the\ndensity rho in the simple fluid or the relative concentration x_A of A in the\nbinary mixture, respectively. The character of phase coexistence changes from a\nspherical droplet (or bubble) of the minority phase (near the coexistence\ncurve) to a cylindrical droplet (or bubble) and finally (in the center of the\nmiscibility gap) to a slab-like configuration of two parallel flat interfaces.\nExtending the analysis of M. Schrader, P. Virnau, and K. Binder [Phys. Rev. E\n79, 061104 (2009)], we extract the surface free energy gamma (R) of both\nspherical and cylindrical droplets and bubbles in the vapor-liquid case, and\npresent evidence that for R -> Infinity the leading order (Tolman) correction\nfor droplets has sign opposite to the case of bubbles, consistent with the\nTolman length being independent on the sign of curvature. For the symmetric\nbinary mixture the expected non-existence of the Tolman length is confirmed. In\nall cases {and for a range of radii} R relevant for nucleation theory, gamma(R)\ndeviates strongly from gamma (Infinity) which can be accounted for by a term of\norder gamma(Infinity)/gamma(R)-1 ~ 1/R^2. Our results for the simple\nLennard-Jones fluid are also compared to results from density functional theory\nand we find qualitative agreement in the behavior of gamma(R) as well as in the\nsign and magnitude of the Tolman length.",
        "positive": "Surface sulci in squeezed soft solids: The squeezing of soft solids, the constrained growth of biological tissues,\nand the swelling of soft elastic solids such as gels can generate large\ncompressive stresses at their surfaces. This causes the otherwise smooth\nsurface of such a solid to becomes unstable when its stress exceeds a critical\nvalue. Previous analyses of the surface instability have assumed\ntwo-dimensional plane-strain conditions, but in experiments isotropic stresses\noften lead to complex three-dimensional sulcification patterns. Here we show\nhow such diverse morphologies arise by numerically modeling the lateral\ncompression of a rigidly clamped elastic layer. For incompressible solids,\nclose to the instability threshold, sulci appear as I-shaped lines aligned\northogonally with their neighbors; at higher compressions they are Y-shaped and\nprefer a hexagonal arrangement. In contrast, highly compressible solids when\nsqueezed show only one sulcified phase characterized by a hexagonal sulcus\nnetwork."
    },
    {
        "anchor": "Sounds of Failure: Passive Acoustic Measurements of Excited Vibrational\n  Modes: Granular materials can fail through spontaneous events like earthquakes or\nbrittle fracture. However, measurements and analytic models which forecast\nfailure in this class of materials, while of both fundamental and practical\ninterest, remain elusive. Materials including numerical packings of spheres,\ncolloidal glasses, and granular materials have been known to develop an excess\nof low-frequency vibrational modes as the confining pressure is reduced. Here,\nwe report experiments on sheared granular materials in which we monitor the\nevolving density of excited modes via passive monitoring of acoustic emissions.\nWe observe a broadening of the distribution of excited modes coincident with\nboth bulk and local plasticity, and clear evolution in the shape of the\ndistribution before and after bulk failure. These results provide a new\ninterpretation of the changing state of the material on its approach to\nstick-slip failure.",
        "positive": "Active transport of a passive colloid in a bath of run-and-tumble\n  particles: The dispersion of a passive colloid immersed in a bath of non-interacting and\nnon-Brownian run-and-tumble microswimmers in two dimensions is analyzed using\nstochastic simulations and an asymptotic theory, both based on a minimal model\nof swimmer-colloid collisions characterized solely by frictionless steric\ninteractions. We estimate the effective long-time diffusivity $\\mathcal{D}$ of\nthe suspended colloid resulting from its interaction with the active bath, and\nelucidate its dependence on the level of activity (persistence length of\nswimmer trajectories), the mobility ratio of the colloid to a swimmer, and the\nnumber density of swimmers in the bath. We also propose a semi-analytical model\nfor the colloid diffusivity in terms of the variance and correlation time of\nthe net fluctuating active force on the colloid resulting from swimmer\ncollisions. Quantitative agreement is found between numerical simulations and\nanalytical results in the experimentally-relevant regime of low swimmer\ndensity, low mobility ratios, and high activity."
    },
    {
        "anchor": "Three-point susceptibilities $\u03c7_n(k;t)$ and $\u03c7_n^s(k;t)$:\n  mode-coupling approximation: Recently, it was argued that a three-point susceptibility equal to the\ndensity derivative of the intermediate scattering function, $\\chi_n(k;t) = d\nF(k;t)/d n$, enters into an expression for the divergent part of an integrated\nfour-point dynamic density correlation function of a colloidal suspension\n[Berthier \\textit{et al.}, J. Chem. Phys. \\textbf{126}, 184503 (2007)]. We show\nthat, within the mode-coupling theory, the equation of motion for $\\chi_n(k;t)$\nis essentially identical as the equation of motion for the $\\mathbf{q}\\to 0$\nlimit of the three-point susceptibility $\\chi_{\\mathbf{q}}(\\mathbf{k};t)$\nintroduced by Biroli \\textit{et al.} [Phys. Rev. Lett. \\textbf{97}, 195701\n(2006)]. We present a numerical solution of the equation of motion for\n$\\chi_n(k;t)$. We also derive and numerically solve an equation of motion for\nthe density derivative of the self-intermediate scattering function,\n$\\chi_n^s(k;t) = d F^s(k;t)/d n$. We contrast the wave vector dependence of\n$\\chi_n(k;t)$ and $\\chi_n^s(k;t)$.",
        "positive": "Fractionalization of Interstitials in Curved Colloidal Crystals: Understanding the out-of equilibrium behaviour of point defects in crystals,\nyields insights into the nature and fragility of the ordered state, as well as\nbeing of great practical importance. In some rare cases defects are\nspontaneously healed - a one-dimensional crystal formed by a line of identical\ncharged particles, for example, can accommodate an interstitial (extra\nparticle) by a re-adjusting all particle positions to even out the spacing. In\nsharp contrast, particles organized into a perfect hexagonal crystal in the\nplane cannot accommodate an interstitial by a simple re-adjustment of the\nparticle spacing - the interstitial remains instead trapped between lattice\nsites and diffuses by hopping, leaving the crystal permanently defected. Here\nwe report on the behavior of interstitials in colloidal crystals on curved\nsurfaces. Using optical tweezers operated independently of three dimensional\nimaging, we insert a colloidal interstitial in a lattice of similar particles\non flat and curved (positively and negatively) oil-glycerol interfaces and\nimage the ensuing dynamics. We find that, unlike in flat space, the curved\ncrystals self-heal through a collective rearrangement that re-distributes the\nincreased density associated with the interstitial. The self-healing process\ncan be interpreted in terms of an out of equilibrium interaction of topological\ndefects with each other and with the underlying curvature. Our observations\nsuggest the existence of \"particle fractionalization\" on curved surface\ncrystals."
    },
    {
        "anchor": "Electromagnetic theory of sound and phonons in liquid: Sound waves in and dielectric liquid, that consists of subsystems of valency\nelectrons with effective mass and ions which interact through the long-wave\npotential electric field are considered, on analogies with and metallic liquid,\nbut with the requirement, that electric current is absent. It is shown that\nusual description of sound wave in an ideal liquid as wave of mass density and\nmass velocity follows from the offered consideration. It is also shown that\nsound waves with other side can be considered as waves of potential electric\nfield in an environment. Introduction of phonons in both cases is considered.",
        "positive": "Design Strategies for Self-Assembly of Discrete Targets: Both biological and artificial self-assembly processes can take place by a\nrange of different schemes, from the successive addition of identical building\nblocks, to hierarchical sequences of intermediates, all the way to the fully\naddressable limit in which each component is unique. In this paper we introduce\nan idealized model of cubic particles with patterned faces that allows\nself-assembly strategies to be compared and tested. We consider a simple\noctameric target, starting with the minimal requirements for successful\nself-assembly and comparing the benefits and limitations of more sophisticated\nhierarchical and addressable schemes. Simulations are performed using a hybrid\ndynamical Monte Carlo protocol that allows self-assembling clusters to\nrearrange internally while still providing Stokes-Einstein-like diffusion of\naggregates of different sizes. Our simulations explicitly capture the\nthermodynamic, dynamic and steric challenges typically faced by self-assembly\nprocesses, including competition between multiple partially-completed\nstructures. Self-assembly pathways are extracted from the simulation\ntrajectories by a fully extendable scheme for identifying structural fragments,\nwhich are then assembled into history diagrams for successfully completed\ntarget structures. For the simple target, a one-component assembly scheme is\nmost efficient and robust overall, but hierarchical and addressable strategies\ncan have an advantage under some conditions if high yield is a priority."
    },
    {
        "anchor": "Wall attraction and repulsion of hydrodynamically interacting particles: We investigate hydrodynamic interaction effects between colloidal particles\nin the vicinity of a wall in the low Reynolds-number limit. Hydrodynamically\ninteracting pairs of beads being dragged by a force parallel to a wall, as for\ninstance during sedimentation, are repelled by the boundary. If a pair of beads\nis trapped by harmonic potentials parallel to the external flow and at the same\ndistance to a wall, then the particle upstream is repelled from the boundary\nwhile its neighbor downstream is attracted. The free end of a semiflexible\nbead-spring polymer-model, which is fixed at one end in a flow near a wall, is\nbent towards the wall by the same reason. The results obtained for point-like\nparticles are exemplarily confirmed by fluid particle dynamics simulations for\nbeads of finite radii, where the shear induced particle rotations either weaken\nor enhance the the effects obtained for point-like particles.",
        "positive": "Elasticity of highly cross-linked random networks: Starting from a microscopic model of randomly cross-linked particles with\nquenched disorder, we calculate the Laudau-Wilson free energy S for arbitrary\ncross-link densities. Considering pure shear deformations, S takes the form of\nthe elastic energy of an isotropic amorphous solid state, from which the shear\nmodulus can be identified. It is found to be an universal quantity, not\ndepending on any microscopic length-scales of the model."
    },
    {
        "anchor": "Inelastic mechanics of sticky biopolymer networks: We propose a physical model for the nonlinear inelastic mechanics of sticky\nbiopolymer networks with potential applications to inelastic cell mechanics. It\nconsists in a minimal extension of the glassy wormlike chain (GWLC) model,\nwhich has recently been highly successful as a quantitative mathematical\ndescription of the viscoelastic properties of biopolymer networks and cells. To\nextend its scope to nonequilibrium situations, where the thermodynamic state\nvariables may evolve dynamically, the GWLC is furnished with an explicit\nrepresentation of the kinetics of breaking and reforming sticky bonds. In spite\nof its simplicity the model exhibits many experimentally established\nnon-trivial features such as power-law rheology, stress stiffening,\nfluidization, and cyclic softening effects.",
        "positive": "The Hydrodynamics of Active Systems: This is a series of four lectures presented at the 2015 Enrico Fermi summer\nschool in Varenna. The aim of the lectures is to give an introduction to the\nhydrodynamics of active matter concentrating on low Reynolds number examples\nsuch as cells and molecular motors. Lecture 1 introduces the hydrodynamics of\nsingle active particles, covering the Stokes equation and the Scallop Theorem,\nand stressing the link between autonomous activity and the dipolar symmetry of\nthe far flow field. In lecture 2 I discuss applications of this mathematics to\nthe behaviour of microswimmers at surfaces and in external flows, and describe\nour current understanding of how swimmers stir the surrounding fluid. Lecture 3\nconcentrates on the collective behaviour of active particles, modelled as an\nactive nematic. I write down the equations of motion and motivate the form of\nthe active stress. The resulting hydrodynamic instability leads to a state\ntermed active turbulence characterised by strong jets and vortices in the flow\nfield and the continual creation and annihilation of pairs of topological\ndefects. Lecture 4 compares simulations of active turbulence to experiments on\nsuspensions of microtubules and molecular motors. I introduce lyotropic active\nnematics and discuss active anchoring at interfaces."
    },
    {
        "anchor": "Comment on 'Statistical mechanics of developable ribbons' by L. Giomi\n  and L. Mahadevan: Giomi and Mahadevan [Phys. Rev. Lett. 104, 238104 (2010)] study the\nstatistical mechanics of elastic ribbons and claim to provide evidence for \"an\nunderlying helical structure\" of ribbon-like polymers even in the absence of\nintrinsic curvature (or, in the authors' words, \"of a preferential\nzero-temperature twist\"). They find a persistence length that is over three\ntimes that of a wormlike chain having the same bending rigidity. We show that\nthese results are an artefact of the authors' flawed formulation, which\nproduces a helical bias, and that no support for the described effect can be\nclaimed.",
        "positive": "Jamming of Bidisperse Frictional Spheres: By generalizing a geometric argument for frictionless spheres, a model is\nproposed for the jamming density $\\phi_J$ of mechanically stable packings of\nbidisperse, frictional spheres. The monodisperse, $\\mu_s$-dependent jamming\ndensity $\\phi_J^{\\mathrm{mono}}(\\mu_s)$ is the only input required in the\nmodel, where $\\mu_s$ is the coefficient of friction. The predictions of the\nmodel are validated by robust estimates of $\\phi_J$ obtained from computer\nsimulations of up to $10^7$ particles for a wide range of $\\mu_s$, and size\nratios up to 40:1. Although $\\phi_J$ varies nonmonotonically with the volume\nfraction of small spheres $f^s$ for all $\\mu_s$, its maximum value\n$\\phi_{J,\\mathrm{max}}$ at an optimal $f^{s}_{\\mathrm{max}}$ are both\n$\\mu_s$-dependent. The optimal $f^{s}_{\\mathrm{max}}$ is characterized by a\nsharp transition in the fraction of small rattler particles."
    },
    {
        "anchor": "The Thermodynamic Origins of Chiral Twist in Monolayer Assemblies of\n  Hard Rod-like Colloids: The propagation of chirality across scales is a common but poorly understood\nphenomenon in soft matter. In this work, we use computer simulations to study\nchiral monolayer assemblies formed by hard rod-like colloidal particles in the\npresence of non-adsorbing polymer and characterize the thermodynamic driving\nforces responsible for the twisting. Simulations show that straight (achiral)\nrods assemble into monolayers with a spontaneous twist that is either left- or\nright-handed, while helical (chiral) rods lead to assemblies with preferential\nchiral features that depend on their handedness and curliness. The onset of\nchirality in these monolayers can be traced back to small clusters formed at\nthe initial stage of the self-assembly. In these microscopic monolayers,\nentropy drives twisting in ways that differ from the assumptions on which\nexisting continuum theory is built. Depending on the geometry of the\nconstituent rods, the preferred chiral twist can be driven by entropy gain of\nthe polymers, or of the rods, or both. In addition, the variation of the\npolymer entropy with twist depends on changes in both the surface area and the\nvolume of the monolayer. Rod fluctuations perpendicular to the monolayer also\nplay an important role in stabilising the twisting.",
        "positive": "Nonadditivity of Critical Casimir Forces: In soft and condensed matter physics, effective interactions often emerge as\na result of the spatial confinement of a fluctuating field. For instance,\nmicroscopic particles in a binary liquid mixture are subject to critical\nCasimir forces whenever their surfaces confine the thermal fluctuations of the\norder parameter of this kind of solvent, the range of which diverges upon\napproaching the critical demixing point. Critical Casimir forces are predicted\nto be nonadditive on a particular large scale. However, a direct experimental\nevidence of this fact is still lacking. Here, we fill in this gap by reporting\nthe experimental measurement of the associated many-body effects. In\nparticular, we focus on three colloidal particles in optical traps and observe\nthat the critical Casimir force exerted on one of them by the other two\ncolloids differs from the sum of the forces they exert separately. The\nmagnitude and range of this three-body effect turn out to depend sensitively on\nthe distance from the critical point of the solvent and on the preferential\nadsorption at the surfaces of the colloids for the two components of the\nmixture."
    },
    {
        "anchor": "Shape of Dynamical Heterogeneities and the Stokes-Einstein and\n  Stokes-Einstein-Debye Relations in Suspensions of Colloidal Ellipsoids: We examine the role of shape of dynamical heterogeneities on the validity of\nthe Stokes-Einstein (SE) and Stokes-Einstein-Debye (SED) relations in\nquasi-two-dimensional suspensions of colloidal ellipsoids. For ellipsoids with\nrepulsive interactions, although the orientational relaxation time remains\ncoupled to the structural one, the SED relation by the Einstein formalism shows\na breakdown. Strikingly, we find that it is the change in the shape of the\ndynamical heterogeneities from string-like to compact and not just their\npresence that results in the breakdown of both the SE and SED relations. On\nintroducing a short-range depletion attraction between the ellipsoids,\nassociated with the lack of morphological evolution of dynamical\nheterogeneities, the SE and SED relations remain valid even for deep\nsupercooling. Our observations are consistent with numerical predictions.",
        "positive": "Two Landmarks in Polymer Physics: The Edwards Model and de Gennes\n  Observation: The impact of two landmark papers one by Edwards and the other by de Gennes\non the field of polymer physics is highlighted."
    },
    {
        "anchor": "Probing shear-induced rearrangements in Fourier Space. II. Differential\n  Dynamic Microscopy: We discuss in two companion papers (arXiv:1802.03737 and the present\nmanuscript) how Fourier-space measurements may be coupled to rheological tests\nin order to elucidate the relationship between mechanical properties and\nmicroscopic dynamics in soft matter. In this second companion paper, we focus\non Differential Dynamic Microscopy (DDM) under shear. We highlight the\nanalogies and the differences with Dynamic Light Scattering coupled to\nrheology, providing a theoretical approach and practical guidelines to separate\nthe contributions to DDM arising from the affine and the non-affine part of the\nmicroscopic displacement field. We show that in DDM under shear the coherence\nof the illuminating source plays a key role, determining the effective sample\nthickness that is probed. Our theoretical analysis is validated by experiments\non 2D samples and 3D gels.",
        "positive": "Fluctuations and Pinch-Offs Observed in Viscous Fingering: Our experiments on viscous (Saffman-Taylor) fingering in Hele-Shaw channels\nreveal several phenomena that were not observed in previous experiments. At low\nflow rates, growing fingers undergo width fluctuations that intermittently\nnarrow the finger as they evolve. The magnitude of these fluctuations is\nproportional to Ca^{-0.64}, where Ca is the capillary number, which is\nproportional to the finger velocity. This relation holds for all aspect ratios\nstudied up to the onset of tip instabilities. At higher flow rates, finger\npinch-off and reconnection events are observed. These events appear to be\ncaused by an interaction between the actively growing finger and suppressed\nfingers at the back of the channel. Both the fluctuation and pinch-off\nphenomena are robust but not explained by current theory."
    },
    {
        "anchor": "Programmable interactions with biomimetic DNA linkers at fluid membranes\n  and interfaces: At the heart of the structured architecture and complex dynamics of\nbiological systems are specific and timely interactions operated by\nbiomolecules. In many instances, biomolecular agents are spatially confined to\nflexible lipid membranes where, among other functions, they control cell\nadhesion, motility and tissue formation. Besides being central to several\nbiological processes, \\emph{multivalent interactions} mediated by reactive\nlinkers confined to deformable substrates underpin the design of\nsynthetic-biological platforms and advanced biomimetic materials. Here we\nreview recent advances on the experimental study and theoretical modelling of a\nheterogeneous class of biomimetic systems in which synthetic linkers mediate\nmultivalent interactions between fluid and deformable colloidal units,\nincluding lipid vesicles and emulsion droplets. Linkers are often prepared from\nsynthetic DNA nanostructures, enabling full programmability of the\nthermodynamic and kinetic properties of their mutual interactions. The coupling\nof the statistical effects of multivalent interactions with substrate fluidity\nand deformability gives rise to a rich emerging phenomenology that, in the\ncontext of self-assembled soft materials, has been shown to produce exotic\nphase behaviour, stimuli-responsiveness, and kinetic programmability of the\nself-assembly process. Applications to (synthetic) biology will also be\nreviewed.",
        "positive": "Chirality-driven edge flow and non-Hermitian topology in active nematic\n  cells: Many of the biological phenomena involve collective dynamics driven by\nself-propelled motion and nonequilibrium force (i.e., activity) that result in\nfeatures unexpected from equilibrium physics. On the other hand, biological\nexperiments utilizing molecular motors, bacteria, and mammalian cells have\nserved as ideal setups to probe the effect of activity in materials and compare\nwith theory. As has been established, however, biomolecules are chiral in\nnature, which can lead to the chiral patterning of cells and even to the\nleft-right symmetry breaking in our body. The general mechanism of how the\ndynamics of bio-matters can couple with its own inherent chirality to produce\nmacroscopic patterns is yet to be elucidated. Here we report that cultured\nneural progenitor cells (NPCs), which undergo self-propelled motion with\nnematic cell-to-cell interactions, exhibit large scale chiral patterns when\nflowing out from containers made by gel. Moreover, a robust chiral cell flow is\nproduced along the boundary when the NPCs are cultured on substrates with\nedges. Perturbation by actomyosin inhibitors allowed control over the\nchirality, resulting in the switching of the direction of the chiral patterning\nand boundary flow. As predicted by a hydrodynamic theory analogous to the\nnon-Hermitian Schrodinger equation, we find an edge-localized unidirectional\nmode in the Fourier spectrum of the cell density, which corresponds to the\ntopological Kelvin wave. These results establish a novel mechanism of flow that\nemerges from a pool of bipolar cells, and demonstrate how topological concepts\nfrom condensed matter physics can naturally arise in chiral active systems and\nmulti-cellular phenomena."
    },
    {
        "anchor": "Comparative analysis of anisotropic material properties of uniaxial\n  nematics formed by flexible dimers and rod-like monomers: We report temperature dependencies of material properties such as dielectric\nanisotropy, birefringence, splay (K11), twist (K22), and bend (K33) elastic\nconstants of the uniaxial nematic (N) phase formed by flexible dimers of DTC5C9\nand compare their behavior to that of a corresponding monomer MCT5. DTC5C9\nforms a twist-bend nematic (Ntb) at temperatures below the N phase. Anisotropic\nproperties of MCT5 are typical of the rod-like mesogens. In particular,\nbirefringence increases as the temperature is reduced, following the classic\nbehavior, described by Haller. The elastic constants also follow the standard\nbehavior, with their ratios being practically temperature-independent. In\ncontrast, DTC5C9 shows a dramatic departure from the standard case.\nBirefringence changes non-monotonously with temperature, decreasing on\napproaching the N-Ntb phase transition. decreases strongly to 0.4 pN near the N\n- Ntb transition, although remains finite. The ratios of the elastic constants\nin DTC5C9 show a strong temperature dependence that can be associated with the\nbend-induced changes in the orientational distribution function. The measured\nelastic properties are consistent with the tendency of the dimeric molecules to\nadopt bent configurations that give rise to the Ntb phase.",
        "positive": "Crosslinked networks of stiff filaments exhibit negative normal stress: Motivated by recent experiments showing that stiff biopolymer gels exhibit\nhighly unusual negative normal elastic stresses, we develop a computational\nmodel for stiff polymer networks subject to large strains. In all cases, we\nfind that such networks develop normal stresses that are both negative and of\nmagnitude comparable to the corresponding shear stress. We find that these\nnormal stresses coincide with other nonlinearities in our networks, and\nspecifically with compressive bucking of the individual filaments. Our results\nsuggest that negative normal stresses are a characteristic feature of stiff\n(bio)polymer gels that have been shown to exhibit strong nonlinear elastic\nproperties."
    },
    {
        "anchor": "Auxetic metamaterials from disordered networks: Recent theoretical work suggests that systematic pruning of disordered\nnetworks consisting of nodes connected by springs can lead to materials that\nexhibit a host of unusual mechanical properties. In particular, global\nproperties such as the Poisson's ratio or local responses related to\ndeformation can be precisely altered. Tunable mechanical responses would be\nuseful in areas ranging from impact mitigation to robotics and, more generally,\nfor creation of metamaterials with engineered properties. However, experimental\nattempts to create auxetic materials based on pruning-based theoretical ideas\nhave not been successful. Here we introduce a new and more realistic model of\nthe networks, which incorporates angle-bending forces and the appropriate\nexperimental boundary conditions. A sequential pruning strategy of select bonds\nin this model is then devised and implemented that enables engineering of\nspecific mechanical behaviors upon deformation, both in the linear and\nnon-linear regimes. In particular, it is shown that the Poisson's ratio can be\ntuned to arbitrary values. The model and concepts discussed here are validated\nby preparing physical realizations of the networks designed in this manner,\nwhich are produced by laser cutting two-dimensional sheets and are found to\nbehave as predicted. Furthermore, by relying on optimization algorithms, we\nexploit the networks' susceptibility to tuning to design networks that posses a\ndistribution of stiffer and more compliant bonds, and whose auxetic behavior is\neven greater than that of homogeneous networks. Taken together, the findings\nreported here serve to establish that pruned networks represent a promising\nplatform for the creation of novel mechanical metamaterials.",
        "positive": "A finite membrane element formulation for surfactants: Surfactants play an important role in various physiological and biomechanical\napplications. An example is the respiratory system, where pulmonary surfactants\nfacilitate the breathing and reduce the possibility of airway blocking by\nlowering the surface tension when the lung volume decreases during exhalation.\nThis function is due to the dynamic surface tension of pulmonary surfactants,\nwhich depends on the concentration of surfactants spread on the liquid layer\nlining the interior surface of the airways and alveoli. Here, a finite membrane\nelement formulation for liquids is introduced that allows for the dynamics of\nconcentration-dependent surface tension, as is the particular case for\npulmonary surfactants. A straightforward approach is suggested to model the\ncontact line between liquid drops/menisci and planar solid substrates, which\nallows the presented framework to be easily used for drop shape analysis. It is\nfurther shown how line tension can be taken into account. Following an\nisogeometric approach, NURBS-based finite elements are used for the\ndiscretization of the membrane surface. The capabilities of the presented\ncomputational model is demonstrated by different numerical examples - such as\nthe simulation of liquid films, constrained and unconstrained sessile drops,\npendant drops and liquid bridges - and the results are compared with\nexperimental data."
    },
    {
        "anchor": "Least-perimeter partition of the disc into $N$ regions of two different\n  areas: We present conjectured candidates for the least perimeter partition of a disc\ninto $N \\le 10$ regions which take one of two possible areas. We assume that\nthe optimal partition is connected, and therefore enumerate all three-connected\nsimple cubic graphs for each $N$. Candidate structures are obtained by\nassigning different areas to the regions: for even $N$ there are $N/2$ regions\nof one area and $N/2$ regions of the other, and for odd $N$ we consider both\ncases, i.e. where the extra region takes either the larger or the smaller area.\nThe perimeter of each candidate is found numerically for a few representative\narea ratios, and then the data is interpolated to give the conjectured least\nperimeter candidate for all possible area ratios. At larger $N$ we find that\nthese candidates are best for a more limited range of the area ratio.",
        "positive": "The relation of steady evaporating drops fed by an influx and freely\n  evaporating drops: We discuss a thin film evolution equation for a wetting evaporating liquid on\na smooth solid substrate. The model is valid for slowly evaporating small\nsessile droplets when thermal effects are insignificant, while wettability and\ncapillarity play a major role. The model is first employed to study steady\nevaporating drops that are fed locally through the substrate. An asymptotic\nanalysis focuses on the precursor film and the transition region towards the\nbulk drop and a numerical continuation of steady drops determines their fully\nnon-linear profiles.\n  Following this, we study the time evolution of freely evaporating drops\nwithout influx for several initial drop shapes. As a result we find that drops\ninitially spread if their initial contact angle is larger than the apparent\ncontact angle of large steady evaporating drops with influx. Otherwise they\nrecede right from the beginning."
    },
    {
        "anchor": "A Critical Assessment of the Boltzmann Approach for Active Systems: Generic models of propelled particle systems posit that the emergence of\npolar order is driven by the competition between local alignment and noise.\nAlthough this notion has been confirmed employing the Boltzmann equation, the\nrange of applicability of this equation remains elusive. We introduce a broad\nclass of mesoscopic collision rules and analyze the prerequisites for the\nemergence of polar order in the framework of kinetic theory. Our findings\nsuggest that a Boltzmann approach is appropriate for weakly aligning systems\nbut is incompatible with experiments on cluster forming systems.",
        "positive": "Onset of flow in a confined colloidal glass under an imposed shear\n  stress: A confined colloidal glass, under the imposition of a uniform shear stress,\nis investigated using numerical simulations. Both at macro- and microscales,\nthe consequent dynamics during the onset of flow is studied. When the imposed\nstress is gradually decreased, the time scale for the onset of steady flow\ndiverges, associated with long-lived spatial heterogeneities. Near this\nyield-stress regime, persistent creep in the form of shear-banded structures is\nobserved."
    },
    {
        "anchor": "Non-affine response: jammed packings versus spring networks: We compare the elastic response of spring networks whose contact geometry is\nderived from real packings of frictionless discs, to networks obtained by\nrandomly cutting bonds in a highly connected network derived from a\nwell-compressed packing. We find that the shear response of packing-derived\nnetworks, and both the shear and compression response of randomly cut networks,\nare all similar: the elastic moduli vanish linearly near jamming, and\ndistributions characterizing the local geometry of the response scale with\ndistance to jamming. Compression of packing-derived networks is exceptional:\nthe elastic modulus remains constant and the geometrical distributions do not\nexhibit simple scaling. We conclude that the compression response of jammed\npackings is anomalous, rather than the shear response.",
        "positive": "Local and Global Expansivity in Water: The supra-molecular structure of a liquid is strongly connected to its\ndynamics which in turn controls macroscopic properties such as viscosity.\nConsequently, detailed knowledge about how this structure changes with\ntemperature is essential to understand the thermal evolution of the dynamics\nranging from the liquid to the glass. Here we combine infrared spectroscopy\n(IR) measurements of the hydrogen (H) bond stretching vibration of water with\nmolecular dynamics simulations and employ a quantitative analysis to extract\nthe inter-molecular H-bond length in a wide temperature range of the liquid.\nThe extracted expansivity of this H-bond differs strongly from that of the\naverage nearest neighbor distance of oxygen atoms obtained through a common\nconversion of mass density. However, both properties can be connected through a\nsimple model based on a random loose packing of spheres with a variable\ncoordination number which demonstrates the relevance of supra-molecular\narrangement. Further, the exclusion of the expansivity of the inter-molecular\nH-bonds reveals that the most compact molecular arrangement is formed in the\nrange $\\sim316-331\\,\\text{K}$ (i.e. above the density maximum) close to the\ntemperature of several pressure-related anomalies which indicates a\ncharacteristic point in the supra-molecular arrangement. These results confirm\nour earlier approach to deduce inter-molecular H-bond lengths via IR in\npolyalcohols [Gabriel et al. 2021] quantitatively and open a new alley to\ninvestigate the role of inter-molecular expansion as a precursor of molecular\nfluctuations on a bond-specific level."
    },
    {
        "anchor": "Self-Similarity in Electrorheological Behavior: In this work we study creep flow behavior of suspension of Polyaniline (PANI)\nparticles in silicone oil under application of electric field. Suspension of\nPANI in silicone oil, a model electrorheological fluid, shows enhancement in\nelastic modulus and yield stress with increase in the magnitude of electric\nfield. Under creep flow field, application of greater magnitude of electric\nfield reduces strain induced in the material while application of greater\nmagnitude of shear stress at any electric field enhances strain induced in the\nmaterial. Remarkably, time evolution of strain in PANI suspension at different\nstresses, electric field strengths and concentrations show superposition after\nappropriate shifting of the creep curves on time and strain axes. Observed\nelectric field - shear stress - creep time - concentration superposition\ndemonstrates self-similarity in electrorheological behavior. We analyze the\nexperimental data using Bingham and Klingenberg - Zukoski model and observe\nthat the latter predicts the experimental behavior very well. We conclude by\ndiscussing remarkable similarities between observed rheological behavior of ER\nfluids and rheological behavior of aging soft glassy materials.",
        "positive": "Rotation-equivariant Graph Neural Networks for Learning Glassy Liquids\n  Representations: Within the glassy liquids community, the use of Machine Learning (ML) to\nmodel particles' static structure is currently a hot topic. The state of the\nart consists in Graph Neural Networks (GNNs), which have a great expressive\npower but are heavy models with numerous parameters and lack interpretability.\nInspired by recent advances in the field of Machine Learning group-equivariant\nrepresentations, we build a GNN that learns a robust representation of the\nglass' static structure by constraining it to preserve the roto-translation\n(SE(3)) equivariance. We show that this constraint not only significantly\nimproves the predictive power but also improves the ability to generalize to\nunseen temperatures while allowing to reduce the number of parameters.\nFurthermore, interpretability is improved, as we can relate the action of our\nbasic convolution layer to well-known rotation-invariant expert features.\nThrough transfer-learning experiments we demonstrate that our network learns a\nrobust representation, which allows us to push forward the idea of a learned\nglass structural order parameter."
    },
    {
        "anchor": "Elastoviscoplastic rheology and ageing in a simplified soft glassy\n  constitutive model: Yield stress fluids display a rich rheological phenomenology. Beyond the\ndefining existence of a yield stress in the steady state flow curve, this\nincludes in many materials rather flat viscoelastic spectra over many decades\nof frequency in small amplitude oscillatory shear; slow stress relaxation\nfollowing the sudden imposition of a small shear strain; stress overshoot in\nshear startup; logarithmic or sublinear power law creep following the\nimposition of a shear stress below the yield stress; creep followed by yielding\nafter the imposition of a shear stress above the yield stress; richly featured\nLissajous-Bowditch curves in large amplitude oscillatory shear; a Bauschinger\neffect, in which a material's effective yield strain is lowered under straining\nin one direction, following a preceding strain in the opposite direction;\nhysteresis in up-down shear rate sweeps; and (in some materials) thixotropy\nand/or rheological ageing. A key challenge is to develop a constitutive model\nthat contains enough underlying mesoscopic physics to have meaningful\npredictive power for the full gamut of rheological behaviour just described,\nwith only a small number of model parameters, and yet is simple enough for use\nin computational fluid dynamics to predict flows in complicated geometries, or\ncomplicated flows that arise due to spontaneous symmetry breaking instabilities\neven in simple geometries. Here we introduce such a model, motivated by the\nwidely used soft glassy rheology model, and show that it captures all the above\nrheological features.",
        "positive": "Lindemann Parameters for solid Membranes focused on Carbon Nanotubes: Temperature fluctuations in the normal direction of planar crystals such as\ngraphene are quite violent and may be expected to influence strongly their\nmelting properties. In particular, they will modify the Lindemann melting\ncriterium. We calculate this modification in a self-consistent Born\napproximation. The result is applied to graphene and its wrapped version\nrepresented by single-walled carbon nanotubes (SWNTs). It is found that the\nout-of-plane fluctuations dominate over the in-plane fluctuations. This makes\nstrong restrictions to possible Lindemann parameters. Astonishing we find that\nthese large out-of-plane fluctuations have only a small influence upon the\nmelting temperature."
    },
    {
        "anchor": "Spin-1/2 fermions on spin-dependent optical lattices: We study the phase diagram of one dimensional spin one-half fermionic cold\natoms. The two ``spin'' species can have different hopping or mass. The phase\ndiagram at equal densities of the species is found to be very rich, Mott\ninsulators as well as superfluids. We also briefly discuss coupling 1D systems\ntogether, and some experimental signatures of these phases. In particular, we\ncompute the spin structure factor in the small momentum limit, which should\nallow the spin gap to be detected.",
        "positive": "Nonlinear viscoelasticity of metastable complex fluids: Many metastable complex fluids such as colloidal glasses and gels show\ndistinct nonlinear viscoelasticity with increasing oscillatory-strain\namplitude; the storage modulus decreases monotonically as the strain amplitude\nincreases whereas the loss modulus has a distinct peak before it decreases at\nlarger strains. We present a qualitative argument to explain this ubiquitous\nbehavior and use mode coupling theory (MCT) to confirm it. We compare\ntheoretical predictions to the measured nonlinear viscoelasticity in a dense\nhard sphere colloidal suspensions; reasonable agreement is obtained. The\nargument given here can be used to obtain new information about linear\nviscoelasticity of metastable complex fluids from nonlinear strain\nmeasurements."
    },
    {
        "anchor": "Anomalous dimensionality dependence of diffusion in a rugged energy\n  landscape : How pathological is one dimension ?: Rugged (or, rough) energy landscape (REL) with spatially distributed maxima\nand minima are often employed in applications of physics, chemistry and biology\n(enzyme kinetics, protein folding, diffusion in disordered solids, transport in\norganic semiconductors, relaxation in random spin systems, in supercooled\nliquids and glasses). Sometimes the system needs to be modeled as a random\nwalker in high dimensions (like in protein folding/unfolding) where dimensions\ncould be the distances between different amino acid residues (as in unfolding\nof HP-36). Nevertheless, most of the theoretical studies of these phenomena\nstill employ a one dimensional description. This is despite the prediction that\nin a rough (or, rugged) energy landscape (REL), diffusion in one dimension (1d)\nis predicted to be pathologically different from any higher dimension with the\nincreased chance of encountering broken ergodicity (Stein and Newman, 2012). We\nexplore the dimensionality dependent diffusion on REL by carrying out an\neffective medium approximation based analytical calculations and compare them\nwith the available computer simulation results. We find that at intermediate\nlevel of ruggedness (assumed to have a Gaussian distribution), where diffusion\nis well-defined, the value of the effective diffusion coefficient depends on\ndimensionality and changes (increases) by several factors (~5-10) in going from\n1d to 2d. In contrast, the changes in subsequent transitions (like 2d to 3d and\n3d to 4d and so on) are far more modest, of the order of 10-20% only. When\nruggedness is given by random traps with an exponential distribution of barrier\nheights, the mean square displacement is sub-diffusive (a well-known result),\nbut the growth of MSD is described by different exponents in one and higher\ndimensions. The exponent of growth is larger in higher dimensions than in 1d.",
        "positive": "All twist and no bend makes raft edges splay: Spontaneous curvature of\n  domain edges in colloidal membranes: Using a combination of theory and experiments we study the interface between\ntwo immiscible domains in a colloidal membrane composed of rigid rods of\ndifferent lengths. Geometric considerations of rigid rod packing imply that a\ndomain of sufficiently short rods in a background membrane of long rods is more\nsusceptible to twist than the inverse structure, a long-rod domain in a\nshort-rod membrane background. The tilt at the inter-domain edge forces splay,\nwhich in turn manifests as a spontaneous edge curvature whose energetics are\ncontrolled by the length asymmetry of constituent rods. A thermodynamic model\nof such tilt-curvature coupling at inter-domain edges explains a number of\nexperimental observations, including a non-monotonic dependence of the edge\ntwist on the domain radius, and annularly shaped domains of long rods. Our work\nshows how coupling between orientational and compositional degrees of freedom\nin two-dimensional fluids give rise to complex shapes and thermodynamics of\ndomains, analogous to shape transitions in 3D fluid vesicles."
    },
    {
        "anchor": "Attraction between like-charged colloidal particles induced by a surface\n  a density - functional analysis: We show that the first non-linear correction to the linearised\nPoisson-Boltzman n (or DLVO) theory of effective pair interactions between\ncharge-stabilised, co lloidal particles near a charged wall leads to an\nattractive component of entro pic origin. The position and depth of the\npotential compare favourably with rec ent experimental measurements",
        "positive": "Large heat-capacity jump in cooling-heating of fragile glass from\n  kinetic Monte Carlo simulations based on a two-state picture: The specific heat capacity $c_v$ of glass formers undergoes a hysteresis when\nsubjected to a cooling-heating cycle, with a larger $c_v$ and a more pronounced\nhysteresis for fragile glasses than for strong ones. Here, we show that these\nexperimental features, including the unusually large magnitude of $c_v$ of\nfragile glasses, are well reproduced by kinetic Monte Carlo and equilibrium\nstudy of a distinguishable particle lattice model (DPLM) incorporating a\ntwo-state picture of particle interactions. The large $c_v$ in fragile glasses\nis caused by a dramatic transfer of probabilistic weight from high-energy\nparticle interactions to low-energy ones as temperature decreases."
    },
    {
        "anchor": "Optimising nanoporous supercapacitors for heat-to-electricity conversion: Innovative ways of harnessing sustainable energy are needed to meet the\nworld's ever-increasing energy demands. Supercapacitors may contribute, as they\ncan convert waste heat to electricity through cyclic charging and discharging\nat different temperatures. Herein, we use an analytically-solvable model of a\ncylindrical pore filled with a single file of ions to identify optimal\nconditions for heat-to-electricity conversion with supercapacitors. We consider\nStirling and Ericsson-like charging cycles and show that the former or latter\nyields more work when a supercapacitor operates under charge or voltage\nlimitations, respectively. Both cycles yield the most work for pores almost as\nnarrow as the size of the ions they contain, as is the case for energy storage\nwith supercapacitors. In contrast to energy storage, which can be maximised by\nionophobic pores, such pores do not yield the best heat-to-electricity\nconversion, independently of the applied potential. Instead, we find that for a\ngiven pore size, a moderately ionophilic pore harvests more work than\nionophobic and strongly ionophilic pores.",
        "positive": "Surfactancy in a tadpole model of proteins: We model the environment of eukaryotic nuclei by representing macromolecules\nby only their entropic properties, with globular molecules represented by\nspherical colloids and flexible molecules by polymers. We put particular focus\non proteins with both globular and intrinsically disordered regions, which we\nrepresent with `tadpole' constructed by grafting single polymers and colloids\ntogether. In Monte Carlo simulations we find these tadpoles support phase\nseparation via depletion flocculation, and demonstrate several surfactant\nbehaviours, including being found preferentially at interfaces and forming\nmicelles in single phase solution. Furthermore, the model parameters can be\ntuned to give a tadpole a preference for either bulk phase. However, we find\nentropy too weak to drive these behaviours by itself at likely biological\nconcentrations."
    },
    {
        "anchor": "Can Polymer Coils be modeled as \"Soft Colloids\"?: We map dilute or semi-dilute solutions of non-intersecting polymer chains\nonto a fluid of ``soft'' particles interacting via a concentration dependent\neffective pair potential, by inverting the pair distribution function of the\ncenters of mass of the initial polymer chains. A similar inversion is used to\nderive an effective wall-polymer potential; these potentials are combined to\nsuccessfully reproduce the calculated exact depletion interaction induced by\nnon-intersecting polymers between two walls. The mapping opens up the\npossibility of large-scale simulations of polymer solutions in complex\ngeometries.",
        "positive": "Rod-like Polyelectrolyte Brushes with Mono- and Multivalent Counterions: A model of rod-like polyelectrolyte brushes in the presence of monovalent and\nmultivalent counterions but with no added-salt is studied using Monte Carlo\nsimulation. The average height of the brush, the histogram of rod\nconformations, and the counterion density profile are obtained for different\nvalues of the grafting density of the charge-neutral wall. For a domain of\ngrafting densities, the brush height is found to be relatively insensitive to\nthe density due to a competition between counterion condensation and inter-rod\nrepulsion. In this regime, multivalent counterions collapse the brush in the\nform of linked clusters. Nematic order emerges at high grafting densities,\nresulting is an abrupt increase of the brush height."
    },
    {
        "anchor": "Visualizing Energy Transfer Between Redox-Active Colloids: Redox-based electrical conduction in nonconjugated polymers has been explored\nless than a decade, yet is already showing promise as a new concept for\nelectrical energy transport. Here using monolayers and sub-monolayers of\ntouching micron-sized redox active colloids (RAC) containing high densities of\nethyl-viologen (EV) side groups, intercolloid redox-based electron transport\nwas directly observed via fluorescence microscopy. This observation was enabled\nby the discovery that these RAC exhibit a highly non-linear\nelectrofluorochromism which can be quantitatively coupled to the colloid redox\nstate. By evaluating the quasi-Fickian nature of the charge transfer (CT)\nkinetics, the apparent CT diffusion coefficient DCT was extracted. Along with\naddressing more fundamental questions regarding energy transport in colloidal\nmaterials, this first real-time real-space imaging of energy transport within\nmonolayers of redox-active colloids may provide insights into energy transfer\nin flow batteries, and enable design of new forms of conductive polymers for\napplications including organic electronics.",
        "positive": "Micro/Nano Motor Navigation and Localization via Deep Reinforcement\n  Learning: Efficient navigation and precise localization of Brownian micro/nano\nself-propelled motor particles within complex landscapes could enable future\nhigh-tech applications involving for example drug delivery, precision surgery,\noil recovery, and environmental remediation. Here we employ a model-free deep\nreinforcement learning algorithm based on bio-inspired neural networks to\nenable different types of micro/nano motors to be continuously controlled to\ncarry out complex navigation and localization tasks. Micro/nano motors with\neither tunable self-propelling speeds or orientations or both, are found to\nexhibit strikingly different dynamics. In particular, distinct control\nstrategies are required to achieve effective navigation in free space and\nobstacle environments, as well as under time constraints. Our findings provide\nfundamental insights into active dynamics of Brownian particles controlled\nusing artificial intelligence and could guide the design of motor and robot\ncontrol systems with diverse application requirements."
    },
    {
        "anchor": "Field Theoretic Study of Bilayer Membrane Fusion: II. Mechanism of a\n  Stalk-Hole Complex: We use self-consistent field theory to determine structural and energetic\nproperties of intermediates and transition states involved in bilayer membrane\nfusion. In particular, we extend our original calculations from those of the\nstandard hemifusion mechanism, which was studied in detail in the first paper\nof this series, to consider a possible alternative to it. This mechanism\ninvolves non-axial stalk expansion, in contrast to the axially symmetric\nevolution postulated in the classical mechanism. Elongation of the initial\nstalk facilitates the nucleation of holes and leads to destabilization of the\nfusing membranes via the formation of a stalk-hole complex. We study properties\nof this complex in detail, and show how transient leakage during fusion,\npreviously predicted and recently observed in experiment, should vary with\nsystem architecture and tension. We also show that the barrier to fusion in the\nalternative mechanism is lower than that of the standard mechanism by a few\n$k_BT$ over most of the relevant region of system parameters, so that this\nalternative mechanism is a viable alternative to the standard pathway.",
        "positive": "First-Principles Approach to Electrorotation Assay: We have presented a theoretical study of electrorotation assay based on the\nspectral representation theory. We consider unshelled and shelled spheroidal\nparticles as an extension to spherical ones. From the theoretical analysis, we\nfind that the coating can change the characteristic frequency at which the\nmaximum rotational angular velocity occurs. The shift in the characteristic\nfrequency is attributed to a change in the dielectric properties of the\nbead-coating complex with respect to those of the uncoated particles. By\nadjusting the dielectric properties and the thickness of the coating, it is\npossible to obtain good agreement between our theoretical predictions and the\nassay data."
    },
    {
        "anchor": "Slow fatigue and highly delayed yielding via shear banding in\n  oscillatory shear: We study theoretically the dynamical process of yielding in cyclically\nsheared amorphous materials, within a thermal elastoplastic model and the soft\nglassy rheology model. Within both models we find an initially slow\naccumulation, over many cycles after the inception of shear, of low levels of\ndamage in the form strain heterogeneity across the sample. This slow fatigue\nthen suddenly gives way to catastrophic yielding and material failure. Strong\nstrain localisation in the form of shear banding is key to the failure\nmechanism. We characterise in detail the dependence of the number of cycles\nbefore failure on the amplitude of imposed strain, the working temperature, and\nthe degree to which the sample is annealed prior to shear. We discuss our\nfinding with reference to existing experiments and particle simulations, and\nsuggest new ones to test our predictions.",
        "positive": "A phase diagram for bacterial swarming: Bacterial swarming is a rapid mass-migration, in which thousands of cells\nspread collectively to colonize a surface. Physically, swarming is a natural\nexample of active particles that use energy to generate motion. Accordingly,\nunderstanding the constraints physics imposes on the dynamics is essential to\nunderstand the mechanisms underlying the swarming phenomenon. We present new\nexperiments of swarming Bacillus subtilis mutants with different aspect ratios\nand densities. Analyzing the dynamics reveals a rich phase diagram of\nqualitatively distinct swarming regimes, describing how the shape and density\nof cells govern the global dynamical characteristics of the entire swarm.\nMoreover, we show that under standard conditions bacteria inhabit a region of\nphase space that is associated with rapid mixing and robust dynamics, with\nhomogeneous density and no preferred direction of motion. This contrasts\ncharacteristic clustering behavior of self-propelled rods that is recovered\nonly for very elongated mutant species. Thus, bacteria have adapted their\nphysics to optimize the principle functions assumed for swarming."
    },
    {
        "anchor": ">>On demand<< triggered crystallization of CaCO3 from solute precursor\n  species: Can we control the crystallization of solid CaCO3 from supersaturated aqueous\nsolutions and thus mimic a natural process predicted to occur in living\norganisms that produce biominerals? Here we show how we achieved this by\nconfining the reaction between Ca2+ and CO32- ions to the environment of\nnanosized water cores of water-in-oil microemulsions. Using a combination of in\nsitu small-angle X-ray scattering, high-energy X-ray diffraction, and low-dose\nliquid-cell scanning transmission electron microscopy, we elucidate how the\npresence of micellar interfaces leads to the formation of a solute CaCO3 phase\nthat can be stabilized for extended periods of time inside micellar water\nnano-droplets. We can also control and >>on-demand<< trigger the actual\nprecipitation and crystallization of solid CaCO3 phases through the targeted\nremoval of the organic-inorganic interfaces.",
        "positive": "Sound propagation and oscillations of a superfluid Fermi gas in the\n  presence of a 1D optical lattice: We develop the hydrodynamic theory of Fermi superfluids in the presence of a\nperiodic potential. The relevant parameters governing the propagation of sound\n(compressibility and effective mass) are calculated in the weakly interacting\nBCS limit. The conditions of stability of the superfluid motion with respect to\ncreation of elementary excitations are discussed.\n  We also evaluate the frequency of the center of mass oscillation when the\nsuperfluid gas is additionally confined by a harmonic trap."
    },
    {
        "anchor": "Slip and friction mechanisms at polymer semi-dilute solutions / solid\n  interfaces: The role of the polymer volume fraction, $\\phi$, on steady state slippage and\ninterfacial friction is investigated for a semi-dilute polystyrene solutions in\ndiethyl phthalate in contact with two solid surfaces. Signicant slippage is\nevidenced for all samples, with slip lengths b obeying a power law dependence.\nThe Navier's interfacial friction coecient, k, is deduced from the slip length\nmeasurements and from independent measurements of the solutions viscosity\n$\\eta$. The observed scaling of k versus $\\phi$ clearly excludes a molecular\nmechanism of friction based on the existence of a depletion layer. Instead, we\nshow that the data of $\\eta$($\\phi$) and k($\\phi$) are understood when taking\ninto account the dependence of the solvent friction on $\\phi$. Two models,\nbased on the friction of blobs or of monomers on the solid surface, well\ndescribe our data. Both points out that the Navier's interfacial friction is a\nsemi-local phenomenon.",
        "positive": "Power law scaling of early-stage forces during granular impact: We experimentally and computationally study the early-stage forces during\nintruder impacts with granular beds in the regime where the impact velocity\napproaches the granular force propagation speed. Experiments use 2D assemblies\nof photoelastic disks of varying stiffness, and complimentary discrete-element\nsimulations are performed in 2D and 3D. The peak force during the initial\nstages of impact and the time at which it occurs depend only on the impact\nspeed, the intruder diameter, the mass density of the grains, and the elastic\nmodulus of the grains according to power-law scaling forms that are not\nconsistent with Poncelet models, granular shock theory, or added-mass models.\nThe insensitivity of our results to many system details suggest that they may\nalso apply to impacts into similar materials like foams and emulsions."
    },
    {
        "anchor": "The jamming surface of granular matter determined from soil mechanics\n  results: Classical soil mechanics results are used to propose the equation of the\njamming transition surface in the (stress, specific volume) space. Taking\naxis-ymmetric conditions, labelling q the deviatoric stress and p' the mean\npressure applied on the granular skeleton, and considering normal range of\npressure (10 kPa-10MPa) the equation of the surface of jamming transition is v\n= vo-m ln(p'/p'o)+ md ln(1+q q/(M' M' p' p')); M' is related to the friction\nangle, m and md are two constants which depend on soil characteristics; p'o is\na \"unit\" pressure.",
        "positive": "Many-body critical Casimir interactions in colloidal suspensions: We study the fluctuation-induced Casimir interactions in colloidal\nsuspensions, especially between colloids immersed in a binary liquid close to\nits critical demixing point. To simulate these systems, we present a highly\nefficient cluster Monte Carlo algorithm based on geometric symmetries of the\nHamiltonian. Utilizing the principle of universality, the medium is represented\nby an Ising system while the colloids are areas of spins with fixed\norientation. Our results for the Casimir interaction potential between two\nparticles at the critical point in two dimensions perfectly agree with the\nexact predictions. However, we find that in finite systems the behavior\nstrongly depends on whether the $Z_{2}$ symmetry of the system is broken by the\nparticles. Eventually we present Monte Carlo results for the three-body Casimir\ninteraction potential and take a close look onto the case of one particle in\nthe vicinity of two adjacent particles, which can be calculated from the\ntwo-particle interaction by a conformal mapping. These results emphasize the\nfailure of the common decomposition approach for many-particle critical Casimir\ninteractions."
    },
    {
        "anchor": "Mesoscale simulations of diffusion and sedimentation in\n  shape-anisotropic nanoparticle suspensions: We determine the long-time self-diffusion coefficient and sedimentation\ncoefficient for suspensions of nanoparticles with anisotropic shapes\n(octahedra, cubes, tetrahedra, and spherocylinders) as a function of\nnanoparticle concentration using mesoscale simulations. We use a discrete\nparticle model for the nanoparticles, and we account for solvent-mediated\nhydrodynamic interactions between nanoparticles using the multiparticle\ncollision dynamics method. Our simulations are compared to theoretical\npredictions and experimental data from existing literature, demonstrating good\nagreement in the majority of cases. Further, we find that the self-diffusion\ncoefficient of the regular polyhedral shapes can be estimated from that of a\nsphere whose diameter is average of their inscribed and circumscribed sphere\ndiameters.",
        "positive": "Origin of attraction between likely charged hydrophobic and hydrophilic\n  walls confining near-critical binary aquaeous mixture with ions: Effect of ionic solute on a near-critical binary aqueous mixture confined\nbetween charged walls with different adsorption preferences is considered\nwithin a simple density functional theory. For the near-critical system\ncontaining small amount of ions a Landau-type functional is derived based on\nthe assumption that the correlation, $\\xi$, and the Debye screening length,\n$\\kappa^{-1}$, are both much larger than the molecular size. The corresponding\napproximate Euler-Lagrange equations aresolved analytically for ions insoluble\nin the organic solvent. Nontrivial concentration profile of the solvent is\nfound near the charged hydrophobic wall as a result of the competition between\nthe short-range attraction of the organic solvent and the electrostatic\nattraction of the hydrated ions. Excess of water may be present near the\nhydrophobic surface for some range of the surface charge and $\\xi\\kappa$. As a\nresult, the effective potential between the hydrophilic and the hydrophobic\nsurface can be repulsive far from the critical point, then attractive and again\nrepulsive when the critical temperature is approached, in agreement with the\nrecent experiment [Nellen at.al., Soft Matter {\\bf 7}, 5360 (2011)]."
    },
    {
        "anchor": "Using Depletion to Control Colloidal Crystal Assemblies of Hard\n  Cuboctahedra: Depletion interactions arise from entropic forces, and their ability to\ninduce aggregation and even ordering of colloidal particles through\nself-assembly is well established, especially for spherical colloids. We vary\nthe size and concentration of penetrable hard sphere depletants in a system of\ncuboctahedra, and we show how depletion changes the preferential facet\nalignment of the colloids and thereby selects different crystal structures.\nMoreover, we explain the cuboctahedra phase behavior using perturbative free\nenergy calculations. We find that cuboctahedra can form a stable simple cubic\nphase, and, remarkably, that the stability of this phase can only be\nrationalized by considering the effects of both the colloid and depletant\nentropy. We corroborate our results by analyzing how the depletant\nconcentration and size affect the emergent directional entropic forces and\nhence the effective particle shape. We propose the use of depletants as a means\nof easily changing the effective shape of self-assembling anisotropic colloids.",
        "positive": "Universal features of polymer shapes in crowded environment: We study the universal characteristics of the shape of a polymer chain in an\nenvironment with correlated structural obstacles, applying the\nfield-theoretical renormalization group approach. Our results qualitatively\nindicate an increase of the asymmetry of the polymer shape in crowded\nenvironment comparing with the pure solution case."
    },
    {
        "anchor": "Far-field approximation for hydrodynamic interactions in parallel-wall\n  geometry: A complete analysis is presented for the far-field creeping flow produced by\na multipolar force distribution in a fluid confined between two parallel planar\nwalls. We show that at distances larger than several wall separations the flow\nfield assumes the Hele-Shaw form, i.e., it is parallel to the walls and varies\nquadratically in the transverse direction. The associated pressure field is a\ntwo-dimensional harmonic function that is characterized by the same multipolar\nnumber m as the original force multipole. Using these results we derive\nasymptotic expressions for the Green's matrix that represents Stokes flow in\nthe wall-bounded fluid in terms of a multipolar spherical basis. This Green's\nmatrix plays a central role in our recently proposed algorithm [Physica A xx,\n{\\bf xxx} (2005)] for evaluating many-body hydrodynamic interactions in a\nsuspension of spherical particles in the parallel-wall geometry. Implementation\nof our asymptotic expressions in this algorithm increases its efficiency\nsubstantially because the numerically expensive evaluation of the exact matrix\nelements is needed only for the neighboring particles. Our asymptotic analysis\nwill also be useful in developing hydrodynamic algorithms for wall-bounded\nperiodic systems and implementing acceleration methods by using corresponding\nresults for the two-dimensional scalar potential.",
        "positive": "Multi-scale coarse-graining for the study of assembly pathways in\n  DNA-brick self assembly: Inspired by recent successes using single-stranded DNA tiles to produce\ncomplex structures, we develop a two-step coarse-graining approach that uses\ndetailed thermodynamic calculations with oxDNA, a nucleotide-based model of\nDNA, to parametrize a coarser kinetic model that can reach the time and length\nscales needed to study the assembly mechanisms of these structures. We test the\nmodel by performing a detailed study of the assembly pathways for a\ntwo-dimensional target structure made up of 334 unique strands each of which\nare 42 nucleotides long. Without adjustable parameters, the model reproduces a\ncritical temperature for the formation of the assembly that is close to the\ntemperature at which assembly first occurs in experiments. Furthermore, the\nmodel allows us to investigate in detail the nucleation barriers and the\ndistribution of critical nucleus shapes for the assembly of a single target\nstructure. The assembly intermediates are compact and highly connected\n(although not maximally so) and classical nucleation theory provides a good fit\nto the height and shape of the nucleation barrier at temperatures close to\nwhere assembly first occurs."
    },
    {
        "anchor": "The metallic state in disordered quasi-one-dimensional conductors: The unusual metallic state in conjugated polymers and single-walled carbon\nnanotubes is studied by dielectric spectroscopy (8--600 GHz). We have found an\nintriguing correlation between scattering time and plasma frequency. This\nrelation excludes percolation models of the metallic state. Instead, the\ncarrier dynamics can be understood in terms of the low density of delocalized\nstates around the Fermi level, which arises from the competion between\ndisorder-induced localization and interchain-interactions-induced\ndelocalization.",
        "positive": "Simulation of charge reversal in salty environments: Giant overcharging?: We have performed MD simulations of a highly charged colloid in a solution of\n3:1 and additional 1:1 salt. The dependency of the colloid's inverted charge on\nthe concentration of the additional 1:1 salt has been studied. Most theories\npredict, that the inverted charge increases when the concentration of\nmonovalent salt grows, up to what is called \"giant overcharging\", while\nexperiments and simulational studies observe the opposite. Our simulations\nagree with the experimental findings and shed light onto the weaknesses of the\ntheories."
    },
    {
        "anchor": "Active Particle Condensation by Nonreciprocal and Time-delayed\n  Interactions: We consider flocking of self-propelling agents in two dimensions, each of\nwhich communicates with its neighbors within a limited vision cone. Also, the\ncommunication occurs with some delay. The communication among the agents are\nmodeled by Vicsek rules. In this study we explore the effect of non-reciprocal\ninteraction among the agents, induced by their vision cone, together with the\ndelayed interactions on the dynamical pattern formation within the flock. We\nfind that under these two influences and without any position based attractive\ninteractions or confining boundaries, the agents can spontaneously condense\ninto drops. Though the agents are in motion within the drop, the drop as whole\nis virtually pinned in space. We also find that this novel state of the flock\nhas a well defined order stabilized by the noise present in the system.",
        "positive": "Effect of mixing and spatial dimension on the glass transition: We study the influence of composition changes on the glass transition of\nbinary hard disc and hard sphere mixtures in the framework of mode coupling\ntheory. We derive a general expression for the slope of a glass transition\nline. Applied to the binary mixture in the low concentration limits, this new\nmethod allows a fast prediction of some properties of the glass transition\nlines. The glass transition diagram we find for binary hard discs strongly\nresembles the random close packing diagram. Compared to 3D from previous\nstudies, the extension of the glass regime due to mixing is much more\npronounced in 2D where plasticization only sets in at larger size disparities.\nFor small size disparities we find a stabilization of the glass phase quadratic\nin the deviation of the size disparity from unity."
    },
    {
        "anchor": "A lattice mesoscopic model of dynamically heterogeneous fluids: We introduce a mesoscopic three-dimensional Lattice Boltzmann Model which\nattempts to mimick the physical features associated with cage effects in\ndynamically heterogeneous fluids. To this purpose, we extend the standard\nLattice Boltzmann dynamics with self-consistent constraints based on the\nnon-local density of the surrounding fluid. The resulting dynamics exhibits\ntypical features of dynamic heterogeneous fluids, such as non-Gaussian density\ndistributions and long-time relaxation. Due to its intrinsically parallel\ndynamics, and absence of statistical noise, the method is expected to compute\nsignificantly faster than molecular dynamics, Monte Carlo and lattice glass\nmodels.",
        "positive": "Equation of state of polydisperse hard-disk mixtures in the high-density\n  regime: A proposal to link the equation of state of a monocomponent hard-disk fluid\nto the equation of state of a polydisperse hard-disk mixture is presented.\nEvent-driven molecular dynamics simulations are performed to obtain data for\nthe compressibility factor of the monocomponent fluid and of 26 polydisperse\nmixtures with different size distributions. Those data are used to assess the\nproposal and to infer the values of the compressibility factor of the\nmonocomponent hard-disk fluid in the metastable region from those of mixtures\nin the high-density region. The collapse of the curves for the different\nmixtures is excellent in the stable region. In the metastable regime, except\nfor two mixtures in which crystallization is present, the outcome of the\napproach exhibits a rather good performance. The simulation results indicate\nthat a (reduced) variance of the size distribution larger than about $0.01$ is\nsufficient to avoid crystallization and explore the metastable fluid branch."
    },
    {
        "anchor": "Ideal Mixing of Paraelectric and Ferroelectric Nematic Phases in Liquid\n  Crystals of Distinct Molecular Species: The organic mesogens RM734 and DIO are members of separate molecular families\nfeaturing distinct molecular structures. These families, at the present time,\nare the only ones known to exhibit a ferroelectric nematic liquid crystal (LC)\nphase. Here we present an experimental investigation of the phase diagram and\nelectro-optics of binary mixtures of RM734 and DIO. We observe paraelectric\nnematic (N) and ferroelectric nematic (NF) phases in both materials, each of\nwhich exhibits complete miscibility across the phase diagram, showing that the\nparaelectric and ferroelectric are the same phases in RM734 as in DIO.\nRemarkably, these molecules form ideal mixtures with respect to both the\nparaelectric-ferroelectric nematic phase behavior and the ferroelectric\npolarization density of the mixtures, the principal order parameter of the\ntransition. Ideal mixing is also manifested in the orientational viscosity, and\nthe onset of glassy dynamics at low temperature. This behavior is attributable\nin part to the similarity of their overall molecular shape and net longitudinal\ndipole moment (~ 11 Debye), and to a common tendency for head-to-tail molecular\nassociation. In contrast, the significant difference in molecular structures\nleads to poor solubility in the crystal phases, enhancing the stability of the\nferroelectric nematic phase at low temperature in the mixtures and making\npossible room temperature electro-optic effects. In the mixtures with excess\nDIO, an intermediate phase appears via an ultraweak, first-order transition\nfrom the N phase, in a narrow temperature range between the paraelectric and\nferroelectric nematics.",
        "positive": "Capillary condensation of saturated vapor in a corner formed by two\n  intersecting walls: The dynamics of saturated vapor between two intersecting walls is examined.\nIt is shown that, if the angle $\\phi$ between the walls is sufficiently small,\nthe vapor becomes unstable, and spontaneous condensation occurs in the corner,\nsimilar to the so-called capillary condensation of vapor into a porous medium.\nAs a result, an ever-growing liquid meniscus develops near the corner. The\ndiffuse-interface model and the lubrication approximation are used to\ndemonstrate that the meniscus grows if and only if $\\phi+2\\theta<\\pi$, where\n$\\theta$ is the contact angle corresponding to the fluid/solid combination\nunder consideration. This criterion has a simple physical explanation: if it\nholds, the meniscus surface is concave -- hence, the Kelvin effect causes\ncondensation. Once the thickness of the condensate exceeds by an order of\nmagnitude the characteristic interfacial thickness, the volume of the meniscus\nstarts to grow linearly with time. If the near-vertex region of the corner is\nsmoothed, the instability can be triggered off only by finite-size\nperturbations, such that include enough liquid to cover the smoothed aria by a\nmicroscopically-thin liquid film."
    },
    {
        "anchor": "Directed transport of polymer drops on vibrating superhydrophobic\n  substrates: A Molecular Dynamics study: Using Molecular Dynamics simulations of a coarse-grained polymer liquid we\ninvestigate the transport of droplets on asymmetrically structured (saw-tooth\nshaped), vibrating substrates. Due to a continuous supply of power by substrate\nvibrations and the asymmetry of its topography, the droplets are driven in a\npreferred direction. We study this directed motion as a function of the size of\nthe droplets, the linear dimensions of the substrate corrugation, and the\nperiod of vibrations.\n  Two mechanisms of driven transport are identified: (i) one that relies on the\ndroplet's contact lines and (ii), in a range of vibration periods, the entire\ncontact area contributes to the driving. In this latter regime, the set-up may\nbe used in experiments for sorting droplets according to their size.\nAdditionally, we show that the linear dimension of the substrate corrugation\naffects the flux inside the droplet. While on a substrate with a fine\ncorrugation droplets mostly slide, on a more coarsely corrugated substrate the\nflux may exhibit an additional rotation pattern.",
        "positive": "Structural Responses of Quasi-2D Colloid Fluids to Excitations Elicited\n  by Nonequilibrium Perturbations: We investigate the response of a dense monodisperse quasi-two-dimensional\n(q2D) colloid suspension when a particle is dragged by a constant velocity\noptical trap. Consistent with microrheological studies of other geometries, the\nperturbation induces a leading density wave and trailing wake, and we use\nStokesian Dynamics (SD) simulations to parse direct colloid-colloid and\nhydrodynamic interactions. We go on to analyze the underlying individual\nparticle-particle collisions in the experimental images. The displacements of\nparticles form chains reminiscent of stress propagation in sheared granular\nmaterials. From these data, we can reconstruct steady-state dipolar flow\npatterns that were predicted for dilute suspensions and previously observed in\ngranular analogs to our system. The decay of this field differs, however, from\npoint Stokeslet calculations, indicating that the finite size of the colloids\nis important. Moreover, there is a pronounced angular dependence that\ncorresponds to the surrounding colloid structure, which evolves in response to\nthe perturbation. Put together, our results show that the response of the\ncomplex fluid is highly anisotropic owing to the fact that the effects of the\nperturbation propagate through the structured medium via chains of\ncolloid-colloid collisions."
    },
    {
        "anchor": "Nonlinear Dynamics of DNA Chain: A couple of models are explained. Helicoidal PB model is studied in more\ndetails. It is shown that semi-discrete approximation yields to breather-type\nsoliton moving along the chain. The model can explain local opening as a\nresonance mode. Also, DNA-RNA transcription is explained through a standing\nsolitary mode.",
        "positive": "The phase behaviour and structure of a fluid confined between competing\n  (solvophobic and solvophilic) walls: We consider a model fluid with long-ranged, dispersion interparticle\npotentials confined between competing parallel walls. One wall is solvophilic\nand would be completely wet at bulk liquid-gas coexistence while the other is\nsolvophobic and would be completely dry at bulk coexistence. When the wall\nseparation L is large and the system is below the bulk critical temperature and\nclose to bulk liquid-gas coexistence, a `delocalized interface' or `soft mode'\nphase forms with a liquid-gas interface near to the centre of the slit; this\ninteracts with the walls via the power-law tails of the interparticle\npotentials. We use a coarse-grained effective Hamiltonian approach to derive\nexplicit scaling expressions for the Gibbs adsorption, the surface tension, the\nsolvation force and the total susceptibility. Using a non-local density\nfunctional theory (DFT) we calculate density profiles for the asymmetrically\nconfined fluid at different chemical potentials and, for sufficiently large L,\nconfirm the scaling predictions for the four thermodynamic quantities. Since\nthe upper critical dimension for complete wetting with power-law potentials is\n<3 we argue that our (mean-field) scaling predictions should remain valid in\ntreatments that incorporate the effects of interfacial fluctuations. As the\nwall separation L is decreased at bulk liquid-gas coexistence we predict a\ncapillary evaporation transition from the `delocalized interface' phase to a\ndilute gas state with just a thin adsorbed film of liquid-like density next to\nthe solvophilic wall. This transition is connected closely to the first order\npre-wetting transition which occurs at the solvophilic wall in the\nsemi-infinite system. We compare the phase diagram for the competing walls\nsystem with the phase diagrams for the fluid confined between identical\nsolvophilic and identical solvophobic walls."
    },
    {
        "anchor": "The square gradient model in a two-phase mixture II. Non-equilibrium\n  properties of a 2D-isotropic interface: In earlier work \\cite{bedeaux/vdW/I, bedeaux/vdW/II, bedeaux/vdW/III} a\nsystematic extension of the van der Waals square gradient model to\nnon-equilibrium one-component systems was given. In this work the focus was on\nheat and mass transfer through the liquid-vapor interface as caused by a\ntemperature difference or an over or under pressure. It was established that\nthe surface as described using Gibbs excess densities was in local equilibrium.\nHeat and mass transfer coefficients were evaluated. In our first paper\n\\cite{glav/gradient/eq/I} we discussed the equilibrium properties of a\nmulti-component system following the same procedure. In particular, we derived\nan explicit expression for the pressure tensor and discussed the validity of\nthe Gibbs relation in the interfacial region. In this paper we will give an\nextension of this approach to multi-component non-equilibrium systems in the\nsystematic context of non-equilibrium thermodynamics. The two-dimensional\nisotropy of the interface is discussed. Furthermore we give numerically\nobtained profiles of the concentration, the mole fraction and the temperature,\nwhich illustrate the solution for some special cases.",
        "positive": "Line tension in a thick soap film: The thickness of freshly made soap films is usually in the micron range, and\ninterference colors make thickness fluctuations easily visible. Circular\npatterns of constant thickness are commonly observed, either a thin film disc\nin a thicker film or the reverse. In this Letter, we evidence the line tension\nat the origin of these circular patterns. Using a well controlled soap film\npreparation, we produce a piece of thin film surrounded by a thicker film. The\nthickness profile, measured with a spectral camera, leads to a line tension of\nthe order of 0.1 nN which drives the relaxation of the thin film shape,\ninitially very elongated, toward a circular shape.A balance between line\ntension and air friction leads to a quantitative prediction of the relaxation\nprocess. Such a line tension is expected to play a role in the production of\nmarginal regeneration patches, involved in soap film drainage and stability."
    },
    {
        "anchor": "Emergent Metric-like States of Active Particles with Metric-free Polar\n  Alignment: We study a model of self-propelled particles interacting with their $k$\nnearest neighbors through polar alignment. By exploring its phase space as a\nfunction of two nondimensional parameters (alignment strength $g$ and Peclet\nnumber $\\mathrm{Pe}$), we identify two distinct order-disorder transitions. One\nis continuous, occurs at a low critical $g$ value independent of Pe, and\nresembles a mean-field transition with no density-order coupling. The other is\ndiscontinuous, depends on a combined control parameter involving $g$ and Pe,\nand results from the formation of small, dense, highly persistent clusters of\nparticles that follow metric-like dynamics. These dense clusters form at a\ncritical value of the combined control parameter $\\mathrm{Pe}/g^{\\alpha}$, with\n$\\alpha \\approx 1.5$, which appears to be valid for different alignment-based\nmodels. Our study shows that models of active particles with metric-free\ninteractions can produce characteristic length-scales and self-organize into\nmetric-like collective states that undergo metric-like transitions.",
        "positive": "New kind of dodecagonal quasicrystal: We report a novel kind of dodecagonal quasicrystal that has so far never been\nobserved, nor theoretically predicted. It is composed of axially stacked\nhexagonal particle layers, with 12-fold rotational symmetry induced by 30\ndegrees rotation of adjacent layers with respect to each other. The\nquasicrystal was produced in a molecular-dynamics simulation of a\nsingle-component system of particles interacting via a spherically-symmetric\npotential, as a result of a first-order phase transition from a liquid phase\nunder constant-density cooling. This finding implies that a similarly\nstructured quasicrystal can possibly be produced by the mesogens of the kind\nthat produce smectic-B crystals and in a system of spherically-shaped colloidal\nparticles with appropriately tuned potential."
    },
    {
        "anchor": "Universal features of complex $n$-block copolymers: We study the conformational properties of complex polymer macromolecules,\nconsisting in general of $n$ subsequently connected chains (blocks) of\ndifferent lengths and distinct chemical structure. Depending on the solvent\nconditions, the inter- or intrachain interactions of some blocks may vanish,\ncausing the rich conformational behavior. Our main attention is focused on the\nuniversal conformational properties of such molecules. Applying the direct\npolymer renormalization group approach, we derive the analytical expressions\nfor the scaling exponent $\\gamma(n)$, governing the number of possible\nconformations of $n$-block copolymer, and analyze the effective linear size\nmeasures of individual blocks. In particular, it is quantitatively estimated\nthe degree of extension of the block sizes as functions of $n$ and position of\nblocks in sequence. The numerical simulations of the simplest $n=2$-block\ncopolymer chain are performed as well for better illustration of the\nconformational behavior of such molecules.",
        "positive": "Buckling transition and boundary layer in non-Euclidean plates: Non-Euclidean plates are thin elastic bodies having no stress-free\nconfiguration, hence exhibiting residual stresses in the absence of external\nconstraints. These bodies are endowed with a three-dimensional reference\nmetric, which may not necessarily be immersible in physical space. Here, based\non a recently developed theory for such bodies, we characterize the transition\nfrom flat to buckled equilibrium configurations at a critical value of the\nplate thickness. Depending of the reference metric, the buckling transition may\nbe either continuous or discontinuous. In the infinitely thin plate limit,\nunder the assumption that a limiting configuration exists, we show that the\nlimit is a configuration that minimizes the bending content, amongst all\nconfigurations with zero stretching content (isometric immersions of the\nmid-surface). For small but finite plate thickness we show the formation of a\nboundary layer, whose size scales with the square root of the plate thickness,\nand whose shape is determined by a balance between stretching and bending\nenergies."
    },
    {
        "anchor": "Thermotropic Phase Transition in an Adsorbed Melissic Acid Film at the\n  n-Hexane - Water Interface: A reversible thermotropic phase transition in an adsorption melissic acid\nfilm at the interface between n-hexane and an aqueous solution of potassium\nhydroxide (pH=10) is investigated by X-ray reflectometry and diffuse scattering\nusing synchrotron radiation. The experimental data indicate that the interface\n\"freezing\" transition is accompanied not only by the crystallization of the\nGibbs monolayer but also by the formation of a planar smectic structure in the\n~300-Angstrom-thick adsorption film; this structure is formed by\n~50-Angstrom-thick layers.",
        "positive": "Twisted vortex state: We study a twisted vortex bundle where quantized vortices form helices\ncircling around the axis of the bundle in a \"force-free\" configuration. Such a\nstate is created by injecting vortices into rotating vortex-free superfluid.\nUsing continuum theory we determine the structure and the relaxation of the\ntwisted state. This is confirmed by numerical calculations. We also present\nexperimental evidence of the twisted vortex state in superfluid 3He-B."
    },
    {
        "anchor": "A molecular dynamics study of chemical gelation in a patchy particle\n  model: We report event-driven molecular dynamics simulations of the irreversible\ngelation of hard ellipsoids of revolution containing several associating\ngroups, characterizing how the cluster size distribution evolves as a function\nof the extent of reaction, both below and above the gel point. We find that in\na very large interval of values of the extent of reaction, parameter-free\nmean-field predictions are extremely accurate, providing evidence that in this\nmodel the Ginzburg zone near the gel point, where non-mean field effects are\nimportant, is very limited. We also find that the Flory's hypothesis for the\npost-gelation regime properly describes the connectivity of the clusters even\nif the long-time limit of the extent of reaction does not reach the fully\nreacted state. This study shows that irreversibly aggregating asymmetric\nhard-core patchy particles may provide a close realization of the mean-field\nmodel, for which available theoretical predictions may help control the\nstructure and the connectivity of the gel state. Besides chemical gels, the\nmodel is relevant to network-forming soft materials like systems with\nbioselective interactions, functionalized molecules and patchy colloids.",
        "positive": "A Universal Nucleation Mechanism for Solvent Cast Polymer Film Rupture: It is shown that the intrinsic stress in solvent cast polymer coatings plays\na key role in the nucleation of holes in the film. Nucleation is important\nbecause it is meanwhile clear that heterogeneous nucleation is the only\nrelevant rupture mechanism for the technologically relevant thickness regime\nwell above 100 nm. The most striking feature is that in contrast to what has\nbeen widely believed, the number density of holes scales not algebraically, but\nexponentially with the film thickness."
    },
    {
        "anchor": "Thermodynamics of Peptide Aggregation Processes. An Analysis from\n  Perspectives of Three Statistical Ensembles: We employ a mesoscopic model for studying aggregation processes of\nprotein-like hydrophobic-polar heteropolymers. By means of multicanonical Monte\nCarlo computer simulations, we find strong indications that peptide aggregation\nis a phase separation process, in which the microcanonical entropy exhibits a\nconvex intruder due to nonnegligible surface effects of the small systems. We\nanalyze thermodynamic properties of the conformational transitions accompanying\nthe aggregation process from the multicanonical, canonical, and microcanonical\nperspective. It turns out that the microcanonical description is particularly\nadvantageous as it allows for unraveling details of the phase-separation\ntransition in the thermodynamic region, where the temperature is not a suitable\nexternal control parameter anymore.",
        "positive": "Active noise-driven particles under space-dependent friction in one\n  dimension: We study a Langevin equation describing the stochastic motion of a particle\nin one dimension with coordinate $x$, which is simultaneously exposed to a\nspace-dependent friction coefficient $\\gamma(x)$, a confining potential $U(x)$\nand non-equilibrium (i.e., active) noise. Specifically, we consider frictions\n$\\gamma(x)=\\gamma_0 + \\gamma_1 | x |^p$ and potentials $U(x) \\propto | x |^n$\nwith exponents $p = 1,2$ and $n = 0, 1, 2$. We provide analytical and numerical\nresults for the particle dynamics for short times and the stationary\nprobability density functions (PDFs) for long times. The short-time behaviour\ndisplays diffusive and ballistic regimes while the stationary PDFs display\nunique characteristic features depending on the exponent values $(p, n)$. The\nPDFs interpolate between Laplacian, Gaussian and bimodal distributions, whereby\na change between these different behaviours can be achieved by a tuning of the\nfriction strengths ratio $\\gamma_0/\\gamma_1$. Our model is relevant for\nmolecular motors moving on a one-dimensional track and can also be realized for\nconfined self-propelled colloidal particles."
    },
    {
        "anchor": "Mutual Synchronization of Spin-Torque Oscillators within a Ring Array: An array of spin torque nano-oscillators (STNOs), coupled by dipolar\ninteraction and arranged on a ring, has been studied numerically and\nanalytically. The phase patterns and locking ranges are extracted as a function\nof the number $N$, their separation, and the current density mismatch between\nselected subgroups of STNOs. If $N\\geq 6$ for identical current densities\nthrough all STNOs, two degenerated modes are identified an in-phase mode (all\nSTNOs have the same phase) and an out-of-phase mode (the phase makes a 2$\\pi$\nturn along the ring). When inducing a current density mismatch between two\nsubgroups, additional phase shifts occur. The locking range (maximum current\ndensity mismatch) of the in-phase mode is larger than the one for the\nout-of-phase mode and depends on the number $N$ of STNOs on the ring as well as\non the separation. These results can be used for the development of magnetic\ndevices that are based on STNO arrays.",
        "positive": "Collective behavior of self-steering active particles with velocity\n  alignment and visual perception: The formation and dynamics of swarms is wide spread in living systems, from\nbacterial bio-films to schools of fish and flocks of birds. We study this\nemergent collective behavior in a model of active Brownian particles with\nvisual-perception-induced steering and alignment interactions through\nagent-based simulations. The dynamics, shape, and internal structure of the\nemergent aggregates, clusters, and swarms of these intelligent active Brownian\nparticles (iABPs) is determined by the maneuverabilities $\\Omega_v$ and\n$\\Omega_a$, quantifying the steering based on the visual signal and polar\nalignment, respectively, the propulsion velocity, characterized by the\nP{\\'e}clet number $Pe$, the vision angle $\\theta$, and the orientational noise.\nVarious non-equilibrium dynamical aggregates -- like motile worm-like swarms\nand millings, and close-packed or dispersed clusters -- are obtained. Small\nvision angles imply the formation of small clusters, while large vision angles\nlead to more complex clusters. In particular, a strong polar-alignment\nmaneuverability $\\Omega_a$ favors elongated worm-like swarms, which display\nsuper-diffusive motion over a much longer time range than individual ABPs,\nwhereas a strong vision-based maneuverability $\\Omega_v$ favors compact, nearly\nimmobile aggregates. Swarm trajectories show long persistent directed motion,\ninterrupted by sharp turns. Milling rings, where a worm-like swarm bites its\nown tail, emerge for an intermediate regime of $Pe$ and vision angles. Our\nresults offer new insights into the behavior of animal swarms, and provide\ndesign criteria for swarming microbots."
    },
    {
        "anchor": "Templated synthesis of cyclic poly(ionic liquid)s: Charged cyclic polymers, e.g. cyclic DNAs and polypeptides, play enabling\nroles in organisms, but their synthesis was challenging due to the well known\npolyelectrolyte effect. To tackle the challenge, we developed a templated\nmethod to synthesize a library of imidazolium and pyridinium based cyclic\npoly(ionic liquid)s. Cyclic templates, cyclic polyimidazole and\npoly(2-pyridine), were synthesized first through ring-closure method by\nlight-induced Diels-Alder click reaction. Through quaternization of cyclic\ntemplates followed by anion metathesis, the cyclic poly(ionic liquid)s were\nsynthesized, which paired with varied counter anions.",
        "positive": "Van der Waals interaction between polymers with sequence-specific\n  polarizabilities: Stiff polymers and flexible Gaussian coils: We consider the van der Waals interaction between a pair of polymers with\nquenched heterogeneous sequences of local polarizabilities along their\nbackbones, and study the effective pairwise interaction energy for both stiff\npolymers and flexible Gaussian coils. In particular, we focus on the cases\nwhere the pair of polarizability sequences are (i)~distinct and (ii)~identical.\nWe find that the pairwise interaction energies of distinct and identical\nGaussian coils are both isotropic and exhibit the same decay behavior for\nseparations larger than the gyration radius, in contradistinction to the\norientationally anisotropic interaction energies of distinct and identical\nstiff polymers. For both Gaussian coils and stiff polymers, the attractive\ninteraction between identical polymers is enhanced if the polarizability\nsequence is more heterogeneous."
    },
    {
        "anchor": "Convective Heat Transport in Compressible Fluids: We present hydrodynamic equations of compressible fluids in gravity as a\ngeneralization of those in the Boussinesq approximation used for nearly\nincompressible fluids. They account for adiabatic processes taking place\nthroughout the cell (the piston effect) and those taking place within plumes\n(the adiabatic temperature gradient effect). Performing two-dimensional\nnumerical analysis, we reveal some unique features of plume generation and\nconvection in transient and steady states of compressible fluids. As the\ncritical point is approached, overall temperature changes induced by plume\narrivals at the boundary walls are amplified, giving rise to overshoot behavior\nin transient states and significant noises of the temperature in steady states.\n  The velocity field is suggested to assume a logarithmic profile within\nboundary layers. Random reversal of macroscopic shear flow is examined in a\ncell with unit aspect ratio. We also present a simple scaling theory for\nmoderate Rayleigh numbers.",
        "positive": "Nonequilibrium interfacial properties of chemically driven fluids: Chemically driven fluids can demix to form condensed droplets that exhibit\nphase behaviors not observed at equilibrium. In particular, nonequilibrium\ninterfacial properties can emerge when the chemical reactions are driven\ndifferentially between the interior and exterior of the phase-separated\ndroplets. Here, we use a minimal model to study changes in the interfacial\ntension between coexisting phases away from equilibrium. Simulations of both\ndroplet nucleation and interface roughness indicate that the nonequilibrium\ninterfacial tension can either be increased or decreased relative to its\nequilibrium value, depending on whether the driven chemical reactions are\naccelerated or decelerated within the droplets. Finally, we show that these\nobservations can be understood using a predictive theory based on an effective\nthermodynamic equilibrium."
    },
    {
        "anchor": "Dynamics in field-induced biaxial nematic liquid crystals of board-like\n  particles: Biaxial nematic ($N_B$) liquid crystals have been indicated as promising\ncandidates for the design of next-generation displays with novel\nelectro-optical properties and faster switching times. While at the molecular\nscale their existence is still under debate, experimental evidence, supported\nby theory and simulation, has unambiguously proved that suitable colloidal\nparticles can indeed form $N_B$ fluids under specific conditions. While this\ndiscovery has sparked a widespread interest in the characterisation of the\nphase behaviour of $N_B$ liquid crystals, significantly less attention has been\ndevoted to the study of their transport properties. To bridge this gap, by\nDynamic Monte Carlo simulations we have investigated the equilibrium dynamics\nof field-induced $N_B$ phases comprising monodisperse hard cuboids. In\nparticular, we calculated the long-time self-diffusion coefficients of cuboids\nover a wide range of anisotropies, spanning prolate to oblate geometries.\nAdditionally, we have compared these diffusivities with those that, upon\nswitching the external field off, are measured in the thermodynamically-stable\nisotropic or uniaxial nematic phases at the same density. Our results indicate\nthat while prolate cuboids diffuse significantly faster in biaxial nematics\nthan in less ordered fluids, we do not observe such an increase with oblate\ncuboids at high packing fractions. We show that these changes are most likely\ndue to the field-induced freezing of the axes perpendicular to the nematic\ndirector, along with a substantial increase in the ordering of the resulting\n$N_B$ phase.",
        "positive": "Discussion on Ohta et al., \"Traveling bands in self-propelled soft\n  particles\": A discussion on the contribution of Ohta and Yamanaka in this special issue,\nsupplemented by new agent-based simulations of band collisions within the\nstandard Vicsek-model."
    },
    {
        "anchor": "Fragility and elastic behavior of a supercooled liquid: A model for the supercooled liquid is considered by taking into account its\nsolid like properties. We focus on how the long time dynamics is affected due\nto the coupling between the slowly decaying density fluctuations and the local\ndisplacement variables in the frozen liquid. Results from our model agree with\nthe recent observation of Novikov and Sokolov [Nature (London) {\\bf 431}, 961\n(2004)] that the fragility index $m$ of a glass forming material is linearly\nrelated to the corresponding ratio $K/G$ of the bulk and the shear moduli.",
        "positive": "Unified Theory of Inertial Granular Flows and Non-Brownian Suspensions: Rheological properties of dense flows of hard particles are singular as one\napproaches the jamming threshold where flow ceases, both for aerial granular\nflows dominated by inertia, and for over-damped suspensions. Concomitantly, the\nlengthscale characterizing velocity correlations appears to diverge at jamming.\nHere we introduce a theoretical framework that proposes a tentative, but\npotentially complete scaling description of stationary flows. Our analysis,\nwhich focuses on frictionless particles, applies {\\it both} to suspensions and\ninertial flows of hard particles. We compare our predictions with the empirical\nliterature, as well as with novel numerical data. Overall we find a very good\nagreement between theory and observations, except for frictional inertial flows\nwhose scaling properties clearly differ from frictionless systems. For\nover-damped flows, more observations are needed to decide if friction is a\nrelevant perturbation or not. Our analysis makes several new predictions on\nmicroscopic dynamical quantities that should be accessible experimentally."
    },
    {
        "anchor": "Double layer for hard spheres with an off-center charge: Simulations for the density and potential profiles of the ions in the planar\nelectrical double layer of a model electrolyte or an ionic liquid are reported.\nThe ions of a real electrolyte or an ionic liquid are usually not spheres; in\nionic liquids, the cations are molecular ions. In the past, this asymmetry has\nbeen modelled by considering spheres that are asymmetric in size and/or valence\n(viz., the primitive model) or by dimer cations that are formed by tangentially\ntouching spheres. In this paper we consider spherical ions that are asymmetric\nin size and mimic the asymmetrical shape through an off-center charge that is\nlocated away from the center of the cation spheres, while the anion charge is\nat the center of anion spheres. The various singlet density and potential\nprofiles are compared to (i) the dimer situation, that is, the constituent\nspheres of the dimer cation are tangentially tethered, and (ii) the standard\nprimitive model. The results reveal the double layer structure to be\nsubstantially impacted especially when the cation is the counterion. As well as\nbeing of intrinsic interest, this off-center charge model may be useful for\ntheories that consider spherical models and introduce the off-center charge as\na perturbation.",
        "positive": "Loss of solutions in shear banding fluids in shear banding fluids driven\n  by second normal stress differences: Edge fracture occurs frequently in non-Newtonian fluids. A similar\ninstability has often been reported at the free surface of fluids undergoing\nshear banding, and leads to expulsion of the sample. In this paper the\ndistortion of the free surface of such a shear banding fluid is calculated by\nbalancing the surface tension against the second normal stresses induced in the\ntwo shear bands, and simultaneously requiring a continuous and smooth meniscus.\nWe show that wormlike micelles typically retain meniscus integrity when shear\nbanding, but in some cases can lose integrity for a range of average applied\nshear rates during which one expects shear banding. This meniscus fracture\nwould lead to ejection of the sample as the shear banding region is swept\nthrough. We further show that entangled polymer solutions are expected to\ndisplay a propensity for fracture, because of their much larger second normal\nstresses. These calculations are consistent with available data in the\nliterature. We also estimate the meniscus distortion of a three band\nconfiguration, as has been observed in some wormlike micellar solutions in a\ncone and plate geometry."
    },
    {
        "anchor": "Probing the mechanical unzipping of DNA: A study of the micromechanical unzipping of DNA in the framework of the\nPeyrard-Bishop-Dauxois model is presented. We introduce a Monte Carlo technique\nthat allows accurate determination of the dependence of the unzipping forces on\nunzipping speed and temperature. Our findings agree quantitatively with\nexperimental results for homogeneous DNA, and for $\\lambda$-phage DNA we\nreproduce the recently obtained experimental force-temperature phase diagram.\nFinally, we argue that there may be fundamental differences between {\\em in\nvivo} and {\\em in vitro} DNA unzipping.",
        "positive": "Emergent collective phenomena in a mixture of hard shapes through active\n  rotation: We investigate collective phenomena with rotationally driven spinners of\nconcave shape. Each spinner experiences a constant internal torque in either a\nclockwise or counterclockwise direction. Although the spinners are modeled as\nhard, otherwise non-interacting rigid bodies, we find that their active motion\ninduces an effective interaction that favors rotation in the same direction.\nWith increasing density and activity, phase separation occurs via spinodal\ndecomposition, as well as self-organization into rotating crystals. We observe\nthe emergence of cooperative, super-diffusive motion along interfaces, which\ncan transport inactive test particles. Our results demonstrate novel phase\nbehavior of actively rotated particles that is not possible with linear\npropulsion or in non-driven, equilibrium systems of identical hard particles."
    },
    {
        "anchor": "Interplay of edge fracture and shear banding in complex fluids: We explore theoretically the interplay between shear banding and edge\nfracture in complex fluids, by performing a detailed simulation study within\ntwo constitutive models: the Johnson-Segalman model and the Giesekus model. We\nconsider separately parameter regimes in which the underlying constitutive\ncurve is monotonic and non-monotonic, such that the bulk flow (in the absence\nof any edge effects) is respectively homogeneous and shear banded. Phase\ndiagrams of the levels of edge disturbance and of bulk (or quasi-bulk) shear\nbanding are mapped as a function of the surface tension of the fluid-air\ninterface, the wetting angle where this interface meets the walls of the flow\ncell, and the imposed shear rate. In particular, we explore in more detail the\nbasic result recently announced in Hemingway et al. (2018): that precursors to\nedge fracture can induce quasi-bulk shear banding. We also appraise analytical\npredictions that shear banding can induce edge fracture, Skorski and Olmsted\n(2011). Although a study of remarkable early insight, that study made some\nstrong assumptions about the nature of the \"base state\", which we examine using\ndirect numerical simulation. The basic prediction that shear banding can cause\nedge fracture remains valid, but with qualitatively modified phase boundaries.",
        "positive": "Writing in Water: Writing is an ancient communication technique dating back at least 30,000\nyears. While even sophisticated contemporary writing techniques hinge on solid\nsurfaces for engraving or the deposition of ink, writing within a liquid medium\nrequires a fundamentally different approach. We here demonstrate writing of\nlines, letters, and complex patterns in water by assembling lines of colloidal\nparticles. Unlike established techniques for underwater writing on solid\nsubstrates, these lines are fully reconfigurable and do not require any\nfixation onto the substrate. Exploiting gravity, we roll an ion-exchange bead\n(pen) across a layer of sedimented colloidal particles (ink). The pen evokes a\nhydrodynamic flow collecting ink-particles into a durable, high-contrast line\nalong its trajectory. Deliberate substrate-tilting sequences facilitate\npen-steering and thus to draw and write. We complement our experiments with a\nminimal model that quantitatively predicts the observed parameter dependence\nfor writing in fluids and highlights the generic character of writing by\nline-assembly. Overall, our approach opens a versatile route for writing,\ndrawing, and patterning fluids - even at the micro-scale."
    },
    {
        "anchor": "Self-diffusion in two-dimensional hard ellipsoid suspensions: We studied the self-diffusion of colloidal ellipsoids in a monolayer near a\nflat wall by video microscopy. The image processing algorithm can track the\npositions and orientations of ellipsoids with sub-pixel resolution. The\ntranslational and rotational diffusions were measured in both the lab frame and\nthe body frame along the long and short axes. The long-time and short-time\ndiffusion coefficients of translational and rotational motions were measured as\nfunctions of the particle concentration. We observed sub-diffusive behavior in\nthe intermediate time regime due to the caging of neighboring particles. Both\nthe beginning and the ending times of the intermediate regime exhibit power-law\ndependence on concentration. The long-time and short-time diffusion\nanisotropies change non-monotonically with concentration and reach minima in\nthe semi-dilute regime because the motions along long axes are caged at lower\nconcentrations than the motions along short axes. The effective diffusion\ncoefficients change with time t as a linear function of (lnt)/t for the\ntranslational and rotational diffusions at various particle densities. This\nindicates that their relaxation functions decay according to 1/t which provides\nnew challenges in theory. The effects of coupling between rotational and\ntranslational Brownian motions were demonstrated and the two time scales\ncorresponding to anisotropic particle shape and anisotropic neighboring\nenvironment were measured.",
        "positive": "Discrete differential geometry-based model for nonlinear analysis of\n  axisymmetric shells: In this paper, we propose a novel one-dimensional (1D) discrete differential\ngeometry (DDG)-based numerical method for geometrically nonlinear mechanics\nanalysis (e.g., buckling and snapping) of axisymmetric shell structures. Our\nnumerical model leverages differential geometry principles to accurately\ncapture the complex nonlinear deformation patterns exhibited by axisymmetric\nshells. By discretizing the axisymmetric shell into interconnected 1D elements\nalong the meridional direction, the in-plane stretching and out-of-bending\npotentials are formulated based on the geometric principles of 1D nodes and\nedges under the Kirchhoff-Love hypothesis, and elastic force vector and\nassociated Hession matrix required by equations of motion are later derived\nbased on symbolic calculation. Through extensive validation with available\ntheoretical solutions and finite element method (FEM) simulations in\nliterature, our model demonstrates high accuracy in predicting the nonlinear\nbehavior of axisymmetric shells. Importantly, compared to the classical\ntheoretical model and three-dimensional (3D) FEM simulation, our model is\nhighly computationally efficient, making it suitable for large-scale real-time\nsimulations of nonlinear problems of shell structures such as instability and\nsnap-through phenomena. Moreover, our framework can easily incorporate complex\nloading conditions, e.g., boundary nonlinear contact and multi-physics\nactuation, which play an essential role in the use of engineering applications,\nsuch as soft robots and flexible devices. This study demonstrates that the\nsimplicity and effectiveness of the 1D discrete differential geometry-based\napproach render it a powerful tool for engineers and researchers interested in\nnonlinear mechanics analysis of axisymmetric shells, with potential\napplications in various engineering fields."
    },
    {
        "anchor": "On the role of flexoelectricity in triboelectricity for randomly rough\n  surfaces: I show how flexoelectricity result in a fluctuating surface electric\npotential when elastic solids with random roughness are squeezed into contact.\nThe flexoelectric potential may induce surface charge distributions and hence\ncontribute to triboelectricity. Using the developed theory I analyze the Kelvin\nForce Microscopy data of Baytekin et al for the electric potential above a\npolydimethylsiloxane (PDMS) surface after it was peeled away from another PDMS\nsurface",
        "positive": "Strong-Coupling Theory for Counter-Ion Distributions: The Poisson-Boltzmann approach gives asymptotically exact counter-ion density\nprofiles around charged objects in the weak-coupling limit of low valency and\nhigh temperature. In this paper we derive, using field-theoretic methods, a\ntheory which becomes exact in the opposite limit of strong coupling. Formally,\nit corresponds to a standard virial expansion. Long-range divergences, which\nrender the virial expansion intractable for homogeneous bulk systems, are shown\nto be renormalizable for the case of inhomogeneous distribution functions by a\nsystematic expansion in inverse powers of the coupling parameter. For a planar\ncharged wall, our analytical results compare quantitatively with extensive\nMonte-Carlo simulations."
    },
    {
        "anchor": "Dielectric and Dilatometric Studies of Glass Transitions in Thin Polymer\n  Films: Dielectric relaxation and thermal expansion spectroscopy were made for thin\npolystyrene films in order to measure the temperature $T_{\\alpha}$\ncorresponding to the peak in the loss component of susceptibility due to the\n$\\alpha$-process and the $\\alpha$-relaxation time $\\tau$ as functions of film\nthickness $d$. While the glass transition temperature $T_{\\rm g}$ decreases\nwith decreasing film thickness, $T_{\\alpha}$ and $\\tau$ were found to remain\nalmost constant for $d>d_{\\rm c}$ and decrease drastically for $d<d_{\\rm c}$\nfor high temperatures. Here, $d_{\\rm c}$ is a critical thickness. Near the\nglass transition temperature, the thickness dependence of $T_{\\alpha}$ and\n$\\tau$ is more prominent. The relation between the fragility index and\nnon-exponentiallity is discussed for thin films of polystyrene.",
        "positive": "Crossover between parabolic and hyperbolic scaling, oscillatory modes\n  and resonances near flocking: A stability and bifurcation analysis of a kinetic equation indicates that the\nflocking bifurcation of the two-dimensional Vicsek model exhibits an interplay\nbetween parabolic and hyperbolic behavior. For box sizes smaller than a certain\nlarge value, flocking appears continuously from a uniform disordered state at a\ncritical value of the noise. Because of mass conservation, the amplitude\nequations describing the flocking state consist of a scalar equation for the\ndensity disturbance from the homogeneous particle density (particle number\ndivided by box area) and a vector equation for a current density. These two\nequations contain two time scales. At the shorter scale, they are a hyperbolic\nsystem in which time and space scale in the same way. At the longer, diffusive,\ntime scale, the equations are parabolic. The bifurcating solution depends on\nthe angle and is uniform in space as in the normal form of the usual pitchfork\nbifurcation. We show that linearization about the latter solution is described\nby a Klein-Gordon equation in the hyperbolic time scale. Then there are\npersistent oscillations with many incommensurate frequencies about the\nbifurcating solution, they produce a shift in the critical noise and resonate\nwith a periodic forcing of the alignment rule. These predictions are confirmed\nby direct numerical simulations of the Vicsek model."
    },
    {
        "anchor": "Conserved Linking in Single- and Double-Stranded Polymers: We demonstrate a variant of the Bond Fluctuation lattice Monte Carlo model in\nwhich moves through cis conformations are forbidden. Ring polymers in this\nmodel have a conserved quantity that amounts to a topological linking number.\nIncreased linking number reduces the radius of gyration mildly. A linking\nnumber of order 0.2 per bond leads to an eight-percent reduction of the radius\nfor 128-bond chains. This percentage appears to rise with increasing chain\nlength, contrary to expectation. For ring chains evolving without the\nconservation of linking number, we demonstrate a substantial anti-correlation\nbetween the twist and writhe variables whose sum yields the linking number. We\nraise the possibility that our observed anti-correlations may have counterparts\nin the most important practical polymer that conserves linking number, DNA.",
        "positive": "Polyelectrolytes in Multivalent Salt Solutions under the Action of DC\n  Electric Fields: We study conformational and electrophoretic properties of polyelectrolytes\n(PEs) in tetravalent salt solutions under the action of electric fields by\nmeans of molecular dynamics simulations. Chain conformations are found to have\na sensitive dependence on salt concentration $C_s$. As $C_s$ is increased, the\nchains first shrink to a globular structure and subsequently reexpand above a\ncritical concentration $C_s^*$. An external electric field can further alter\nthe chain conformation. If the field strength $E$ is larger than a critical\nvalue $E^*$, the chains are elongated. $E^*$ is shown to be a function of $C_s$\nby using two estimators $E_{I}^*$ and $E_{II}^*$ through the study of the\npolarization energy and the onset point of chain unfolding, respectively. The\nelectrophoretic mobility of the chains depends strongly on $C_s$, and the\nmagnitude increases significantly, accompanying the chain unfolding, when $E>\nE_{II}^*$. We study the condensed ion distributions modified by electric fields\nand discuss the connection of the modification with the change of chain\nmorphology and mobility. Finally, $E^*$ is studied by varying the chain length\n$N$. The inflection point is used as a third estimator $E_{III}^*$. $E_{III}^*$\nscales as $N^{-0.63(4)}$ and $N^{-0.76(2)}$ at $C_s=0.0$ and $C_s^*$,\nrespectively. $E_{II}^*$ follows a similar scaling law to $E_{III}^*$ but a\ncrossover appears at $C_s=C_s^*$ when $N$ is small. The $E_{I}^*$ estimator\nfails to predict the critical field, which is due to oversimplifying the\ncritical polarization energy to the thermal energy. Our results provide\nvaluable information to understand the electrokinetics of PE solutions at the\nmolecular level and could be helpful in micro/nano-fluidics applications."
    },
    {
        "anchor": "Elastic octopoles and colloidal structures in nematic liquid crystals: We propose a simple theoretical model which explains a formation of dipolar\n2D and 3D colloidal structures in nematic liquid crystal. Colloidal particles\nare treated as effective hard spheres interacting via their elastic dipole,\nquadrupole and octopole moments. It is shown that octopole moment plays an\nimportant role in the formation of 2D and 3D nematic colloidal crystals. We\ngeneralize this assumption on the case of the external electric field and\ntheoretically explain a giant electrostriction effect in 3D crystals observed\nrecently [A. Nych et al., Nature Communications \\textbf{4}, 1489 (2013)].",
        "positive": "Adsorption of hard spheres: structure and effective density according to\n  the potential distribution theorem: We propose a new type of effective densities via the potential distribution\ntheorem. These densities are for the sake of enabling the mapping of the free\nenergy of a uniform fluid onto that of a nonuniform fluid. The potential\ndistribution theorem gives the work required to insert a test particle into the\nbath molecules under the action of the external (wall) potential. This\ninsertion work W_ins can be obtained from Monte Carlo (MC) simulation (e.g.\nfrom Widom's test particle technique) or from an analytical theory. The\npseudo-densities are constructed thusly so that when their values are\nsubstituted into a uniform-fluid equation of state (e.g. the Carnahan-Starling\nequation for the hard-sphere chemical potentials), the MC nonuniform insertion\nwork is reproduced. We characterize the pseudo-density behavior for the hard\nspheres/hard wall system at moderate to high densities (from \\rho^*= 0.5745 to\n0.9135). We adopt the MC data of Groot et al. for this purpose. The\npseudo-densities show oscillatory behavior out of phase (opposite) to that of\nthe singlet densities. We also construct a new closure-based density functional\ntheory (the star-function based density functional theory) that can give\naccurate description of the MC density profiles and insertion works. A viable\ntheory is established for several cases in hard sphere adsorption."
    },
    {
        "anchor": "Universal Elasticity and Fluctuations of Nematic Gels: We study elasticity of spontaneously orientationally-ordered amorphous\nsolids, characterized by a vanishing transverse shear modulus, as realized for\nexample by nematic elastomers and gels. We show that local heterogeneities and\nelastic nonlinearities conspire to lead to anomalous nonlocal universal\nelasticity controlled by a nontrivial infared fixed point. Namely, at long\nscales, such solids are characterized by universal shear and bending moduli\nthat, respectively, vanish and diverge at long scales, are universally\nincompressible and exhibit a universal negative Poisson ratio and a non-Hookean\nelasticity down to arbitrarily low strains. Based on expansion about five\ndimensions, we argue that the nematic order is stable to thermal fluctuation\nand local hetergeneities down to d_lc < 3.",
        "positive": "Crack front \u00e9chelon instability in mixed mode fracture of a strongly\n  nonlinear elastic solid: Mixed mode (I+III) loading induces segmented crack front \\'echelon structures\nconnected by steps. We study this instability in a highly deformable,\nstrain-hardening material. We find that \\'echelons develop beyond a finite,\nsize-independent mode mixity threshold, markedly growing with energy release\nrate. They appear via nucleation of localized helical front distortions, and\ntheir emergence is the continuation of the mode I cross-hatching instability of\ngels and rubbers, shifted by the biasing effect of shear. This result, at odds\nwith the direct bifurcation predicted by linear elastic fracture mechanics, can\nbe assigned to the controlling role of elastic nonlinearity."
    },
    {
        "anchor": "Conductance of ion channels and nanopores with charged walls: a toy\n  model: We consider ion transport through protein ion channels in lipid membranes and\nwater-filled nanopores in silicon films. It is known that, due to the large\nratio of dielectric constants of water and the surrounding material, an ion\nplaced inside the channel faces a large electrostatic self-energy barrier. The\nbarrier leads to an exponentially large resistance of the channel. We study\nreduction of the electrostatic barrier by immobile charges located on the\ninternal walls of the channel. We show that the barrier practically vanishes\nalready at relatively small concentration of wall charges.",
        "positive": "Translocation Dynamics with Attractive Nanopore-Polymer Interactions: Using Langevin dynamics simulations, we investigate the influence of\npolymer-pore interactions on the dynamics of biopolymer translocation through\nnanopores. We find that an attractive interaction can significantly change the\ntranslocation dynamics. This can be understood by examining the three\ncomponents of the total translocation time $\\tau \\approx \\tau_1+\\tau_2+\\tau_3$\ncorresponding to the initial filling of the pore, transfer of polymer from the\n\\textit{cis} side to the \\textit{trans} side, and emptying of the pore,\nrespectively. We find that the dynamics for the last process of emptying of the\npore changes from non-activated to activated in nature as the strength of the\nattractive interaction increases, and $\\tau_3$ becomes the dominant\ncontribution to the total translocation time for strong attraction. This leads\nto a new dependence of $\\tau$ as a function of driving force and chain length.\nOur results are in good agreement with recent experimental findings, and\nprovide a possible explanation for the different scaling behavior observed in\nsolid state nanopores {\\it vs.} that for the natural $\\alpha$-hemolysin\nchannel."
    },
    {
        "anchor": "Vascular journey and adhesion mechanics of micro-sized carriers in\n  narrow capillaries: In this work a Lattice Boltzmann Immersed Boundary method is used for\npredicting the dynamics of rigid and deformable adhesive micro carriers (1 um)\nnavigating a capillary by the size of 10 um with 20% hematocrit. Red cells and\nparticles are modeled as a collection of mass spring elements responding to a\nbending potential, an elastic potential and total enclosed area conservation\nconstraint. Furthermore, particle surfaces are uniformly decorated with\nadhesive molecules (ligands) interacting with receptors disposed on the walls.\nParticle adhesion is modeled as a short range ligad receptor interaction and in\nterm of formation and destruction probability functions that discriminate\nwhether a chemical bond can be formed or destroyed. If a bond is established an\nattractive elastic force is activated. Particle transport and adhesion are\ncharacterized in terms of their ability to reach the capillary peripheries\n(margination rate) and firmly adhere the vasculature. This analysis is carried\nout systematically by varying particles' and cells' releasing positions and\nstiffness (Ca = 0 and 10-2). Moreover, three rigid and soft representative\nparticles are transported on a finer mesh (Dx = 15 nm) and the chemical\nstrength of their adhesive coating is varied (s = 0.5, 1.0, and 2.0) to\nprecisely analyze the resulting adhesion mechanics. Stiffness is found to\nweakly influence the margination rate while significantly affect the ability of\nsuch constructs to efficiently interact with the endothelium by forming stable\nchemical bonds.",
        "positive": "Predicting Ion Sequestration in Charged Polymers with the\n  Steepest-Entropy-Ascent Quantum Thermodynamic Framework: The steepest-entropy-ascent quantum thermodynamic framework is used to\ninvestigate the effectiveness of multi-chain\npolyethyleneimine-methylenephosphonic acid in sequestering rare-earth ions\n(Eu$^{+3}$) from aqueous solutions. The framework applies a thermodynamic\nequation of motion to a discrete energy eigenstructure to model the binding\nkinetics of europium ions to reactive sites of the polymer chains. The energy\neigenstructure is generated using a non-Markovian Monte Carlo model that\nestimates energy level degeneracies. The equation of motion is used to\ndetermine the occupation probability of each energy level, describing the\nunique path through thermodynamic state space by which the polymer system\nsequesters rare-earth ions from solution. A second Monte Carlo simulation is\nconducted to relate the kinetic path in state space to physical descriptors\nassociated with the polymer, including the radius of gyration, tortuosity, and\nEu-neighbor distribution functions. These descriptors are used to visualize the\nevolution of the polymer during the sequestration process. The fraction of\nsequestered Eu$^{+3}$ ions depends upon the total energy of the system, with\nlower energy resulting in higher sequestration. The kinetics of the overall\nsequestration are dependent on the steepest-entropy-ascent principle used by\nthe equation of motion to generate a unique kinetic path from an initial\nnon-equilibrium state."
    },
    {
        "anchor": "Helfrich-Canham bending energy as a constrained non-linear sigma model: The Helfrich-Canham bending energy is identified with a non-linear sigma\nmodel for a unit vector. The identification, however, is dependent on one\nadditional constraint: that the unit vector be constrained to lie orthogonal to\nthe surface. The presence of this constraint adds a source to the divergence of\nthe stress tensor for this vector so that it is not conserved. The stress\ntensor which is conserved is identified and its conservation shown to reproduce\nthe correct shape equation.",
        "positive": "Structure and Short-time Dynamics in Suspensions of Charged Silica\n  Spheres in the entire Fluid Regime: We present an experimental study of short-time diffusion properties in\nfluid-like suspensions of monodisperse charge-stabilized silica spheres\nsuspended in DMF. The static structure factor S(q), the short-time diffusion\nfunction, D(q), and the hydrodynamic function, H(q), in these systems have been\nprobed by combining X-ray photon correlation spectroscopy experiments with\nstatic small-angle X-ray scattering. Our experiments cover the full\nliquid-state part of the phase diagram, including deionized systems right at\nthe liquid-solid phase boundary. We show that the dynamic data can be\nconsistently described by the renormalized density fluctuation expansion theory\nof Beenakker and Mazur over a wide range of concentrations and ionic strengths.\nIn accord with this theory and Stokesian dynamics computer simulations, the\nmeasured short-time properties cross over monotonically, with increasing salt\ncontent, from the bounding values of salt-free suspensions to those of neutral\nhard spheres. Moreover, we discuss an upper bound for the hydrodynamic function\npeak height of fluid systems based on the Hansen-Verlet freezing criterion."
    },
    {
        "anchor": "Solid Surface Structure Affects Liquid Order at the Polystyrene/SAM\n  Interface: We present a combined x-ray and neutron reflectivity study characterizing the\ninterface between polystyrene (PS) and silanized surfaces. Motivated by the\nlarge difference in slip velocity of PS on top of dodecyl-trichlorosilane (DTS)\nand octadecyl-trichlorosilane (OTS) found in previous studies, these two\nsystems were chosen for the present investigation. The results reveal the\nmolecular conformation of PS on silanized silicon. Differences in the molecular\ntilt of OTS and DTS are replicated by the adjacent phenyl rings of the PS. We\ndiscuss our findings in terms of a potential link between the microscopic\ninterfacial structure and dynamic properties of polymeric liquids at\ninterfaces.",
        "positive": "Self-Consistent Description of Vapor-Liquid Interface in Ionic Fluids: Inhomogeneity of ion correlation widely exists in many physicochemical, soft\nmatter, and biological systems. Here, we apply the modified Gaussian\nrenormalized fluctuation theory to study the classic example of the\nvapor-liquid interface of ionic fluids. The ion correlation is decomposed into\na short-range contribution associated with the local electrostatic environment\nand a long-range contribution accounting for the spatially varying ionic\nstrength and dielectric permittivity. For symmetric salt, both the coexistence\ncurve and the interfacial tension predicted by our theory are in quantitative\nagreement with simulation data reported in the literature. Furthermore, we\nprovide the first theoretical prediction of interfacial structure for\nasymmetric salt, highlighting the importance of capturing local charge\nseparation."
    },
    {
        "anchor": "Healing Regimes for Microscopic Wounds in the Vertex Model of Cell\n  Tissues: Wounds in epithelial tissues compromise their vital role in homeostasis. A\nrapid and efficient wound healing encompasses different mechanisms, which\nincludes the formation of a contractile actin-myosin cable around its edge,\nknown as the purse-string mechanism. We combine mean-field calculations and\nnumerical simulations of the Vertex model to study the interplay between tissue\nproperties and the purse-string mechanism and its impact on the healing\nprocess. We find different regimes, where the wound opens, closes partially or\ncompletely. We also derive an analytic expression for the closure time which is\nvalidated by numerical simulations. This study establishes under which\nconditions the purse-string mechanism suffices for closure, providing an\nanalytical mean-field expression for the respective thresholds.",
        "positive": "Strain-dependent localization, microscopic deformations, and macroscopic\n  normal tensions in model polymer networks: We use molecular dynamics simulations to investigate the microscopic and\nmacroscopic response of model polymer networks to uniaxial elongations. By\nstudying networks with strands lengths ranging from $N_s=20$ to 200 we cover\nthe full crossover from cross-link to entanglement dominated behavior. Our\nresults support a recent version of the tube model which accounts for the\ndifferent strain dependence of chain localization due to chemical cross-links\nand entanglements."
    },
    {
        "anchor": "Adsorption isotherms of charged nanoparticles: We present theory and simulations which allow us to quantitatively calculate\nthe amount of surface adsorption excess of charged nanoparticles onto a charged\nsurface. The theory is very accurate for weakly charged nanoparticles and can\nbe used at physiological concentrations of salt. We have also developed an\nefficient simulation algorithm which can be used for dilute suspensions of\nnanoparticles of any charge, even at very large salt concentrations. With the\nhelp of the new simulation method, we are able to efficiently calculate the\nadsorption isotherms of highly charged nanoparticles in suspensions containing\nmultivalent ions, for which there are no accurate theoretical methods\navailable.",
        "positive": "Lift and drag in intruders moving through hydrostatic granular media at\n  high speeds: Recently, experiments showed that forces on intruders dragged horizontally\nthrough dense, hydrostatic granular packings mainly depend on the local surface\norientation and can be seen as the sum of the forces exerted on small surface\nelements. In order to understand such forces more deeply, we perform 2D\nsoft-sphere molecular dynamics simulation, on similar set up, of an intruder\ndragged through a 50-50 bi-disperse granular packing, with diameters 0.30 and\n0.34 cm. We measure, for both circular and half-circle shapes, the forces\nparallel (drag) and perpendicular (lift) to the drag direction as functions of\nthe drag speed, with V=10.3-309 cm/s, and intruder depths, with D=3.75-37.5 cm.\nThe drag forces on an intruder monotonically increase with V and D, and are\nlarger for the circle. However, the lift force does not depend monotonically on\nV and D, and this relationship is affected by the shape of the intruder. The\nvertical force was negative for the half-circle, but for a small range of V and\nD, we measure positive lift. We find no sign change for the lift on the circle,\nwhich is always positive. The explanation for the nonmonotonic dependence is\nrelated to the decrease in contacts on the intruder as V increases. This is\nqualitatively similar to supersonic flow detachment from an obstacle. The\ndetachment picture is supported by simulation measurements of the velocity\nfield around the intruder and force profiles measured on its surface."
    },
    {
        "anchor": "The \u03b8-formulation of the 2D elastica -- Buckling and boundary layer\n  theory: The equations of a planar elastica under pressure can be rewritten in a\nuseful form by parametrising the variables in terms of the local orientation\nangle, $\\theta$, instead of the arc length. This ``$\\theta$-formulation'' lends\nitself to a particularly easy boundary layer analysis in the limit of weak\nbending stiffness. Within this parameterization, boundary layers are located at\ninflexion points, where $\\theta$ is extremum, and they connect regions of low\nand large curvature. A simple composite solution is derived without resorting\nto elliptic functions and integrals. This approximation can be used as an\nelementary building block to describe complex shapes. Applying this theory to\nthe study of an elastic ring under uniform pressure and subject to a set of\npoint forces, we discover a snapping instability. This instability is confirmed\nby numerical simulations. Finally, we carry out experiments and find good\nagreement of the theory with the experimental shape of the deformed elastica.",
        "positive": "A density functional approach to ferrogels: Ferrogels consist of magnetic colloidal particles embedded in an elastic\npolymer matrix. As a consequence, their structural and rheological properties\nare governed by a competition between magnetic particle-particle interactions\nand mechanical matrix elasticity. Typically, the particles are permanently\nfixed within the matrix, which makes them distinguishable by their positions.\nOver time, particle neighbors do not change due to the fixation by the matrix.\nHere we present a classical density functional approach for such ferrogels. We\nmap the elastic matrix-induced interactions between neighboring colloidal\nparticles distinguishable by their positions onto effective pairwise\ninteractions between indistinguishable particles similar to a \"pairwise\npseudopotential\". Using Monte-Carlo computer simulations, we demonstrate for\none-dimensional dipole-spring models of ferrogels that this mapping is\njustified. We then use the pseudopotential as an input into classical density\nfunctional theory of inhomogeneous fluids and predict the bulk elastic modulus\nof the ferrogel under various conditions. In addition, we propose the use of an\n\"external pseudopotential\" when one switches from the viewpoint of a\none-dimensional dipole-spring object to a one-dimensional chain embedded in an\ninfinitely extended bulk matrix. Our mapping approach paves the way to describe\nvarious inhomogeneous situations of ferrogels using classical density\nfunctional concepts of inhomogeneous fluids."
    },
    {
        "anchor": "Comment on \"Writhe formulas and antipodal points in plectonemic DNA\n  configurations\": We point out that the disagreement between the paper by Neukirch and\nStarostin (Ref.[1]) and ours (Ref. [5]) is only apparent and stems from a\ndifference in approach. Ref. [1] is concerned with classical elasticity and\nindividual curves while Ref. [5] focuses on statistical averages over curves.",
        "positive": "Effect of Shape and Friction on the Packing and Flow of Granular\n  Materials: The packing and flow of aspherical frictional particles are studied using\ndiscrete element simulations. Particles are superballs with shape\n$|x|^{s}+|y|^{s}+|z|^{s} = 1$ that varies from sphere ($s=2$) to cube\n($s=\\infty$), constructed with an overlapping-sphere model. Both packing\nfraction, $\\phi$, and coordination number, $z$, decrease monotonically with\nmicroscopic friction $\\mu$, for all shapes. However, this decrease is more\ndramatic for larger $s$ due to a reduction in the fraction of face-face\ncontacts with increasing friction. For flowing grains, the dynamic friction\n$\\tilde{\\mu}$ - the ratio of shear to normal stresses - depends on shape,\nmicroscopic friction and inertial number $I.$ For all shapes, $\\tilde{\\mu}$\ngrows from its quasi-static value $\\tilde{\\mu}_0$ as\n$(\\tilde{\\mu}-\\tilde{\\mu}_0) = dI^\\alpha,$ with different universal behavior\nfor frictional and frictionless shapes. For frictionless shapes the exponent\n$\\alpha \\approx 0.5$ and prefactor $d \\approx 5\\tilde{\\mu}_0$ while for\nfrictional shapes $\\alpha \\approx 1$ and $d$ varies only slightly. The results\nhighlight that the flow exponents are universal and are consistent for all the\nshapes simulated here."
    },
    {
        "anchor": "Microstructure evolution of compressible granular systems under large\n  deformations: We report three-dimensional particle mechanics static calculations that\npredict the microstructure evolution during die-compaction of elastic spherical\nparticles up to relative densities close to one. We employ a nonlocal contact\nformulation that remains predictive at high levels of confinement by removing\nthe classical assumption that contacts between particles are formulated locally\nas independent pair-interactions. The approach demonstrates that the\ncoordination number depends on the level of compressibility, i.e., on the\nPoisson's ratio, of the particles. Results also reveal that distributions of\ncontact forces between particles and between particles and walls, although\nsimilar at jamming onset, are very different at full compaction. Particle-wall\nforces are in remarkable agreement with experimental measurements reported in\nthe literature, providing a unifying framework for bridging experimental\nboundary observations with bulk behavior.",
        "positive": "Anisotropic hysteresis on ratcheted superhydrophobic surfaces: We consider the equilibrium behaviour and dynamics of liquid drops on a\nsuperhydrophobic surface patterned with sawtooth ridges or posts. Due to the\nanisotropic geometry of the surface patterning, the contact line can\npreferentially depin from one side of the ratchets, leading to a novel,\npartially suspended, superhydrophobic state. In both this configuration, and\nthe collapsed state, the drops show strong directional contact angle hysteresis\nas they are pushed across the surface. The easy direction is, however,\ndifferent for the two states. This observation allows us to interpret recent\nexperiments describing the motion of water drops on butterfly wings."
    },
    {
        "anchor": "The influence of material properties and process parameters on the\n  spreading process in additive manufacturing: Laser powder bed fusion (LPBF) is an additive manufacturing (AM) technology.\nTo achieve high product quality, the powder is best spread as a uniform, dense\nlayer. The challenge for LPBF manufacturers is to develop a spreading process\nthat can produce a consistent layer quality for the many powders used, which\nshow considerable differences in spreadability. Therefore, we investigate the\ninfluence of material properties, process parameters and the type of spreading\ntool on the layer quality. The discrete particle method is used to simulate the\nspreading process and to define metrics to evaluate the powder layer\ncharacteristics. We found that particle shape and surface roughness in terms of\nrolling resistance and interparticle sliding friction as well as particle\ncohesion all have a major (sometimes surprising) influence on the powder layer\nquality: more irregular shaped particles, rougher particle surfaces and/or\nhigher interfacial cohesion usually, but not always, lead to worse\nspreadability. Our findings illustrate that there is a trade-off between\nmaterial properties and process parameters. Increasing the spreading speed\ndecreases layer quality for non- and weakly cohesive powders, but improves it\nfor strongly cohesive ones. Using a counter-clockwise rotating roller as a\nspreading tool improves the powder layer quality compared to spreading with a\nblade. Finally, for both geometries, a unique correlation between the quality\ncriteria uniformity and mass fraction is reported and some of the findings are\nrelated to size-segregation during spreading.",
        "positive": "Anchoring-dependent bifurcation in nematic microflows within cylindrical\n  capillaries: Capillary microflows of liquid crystal phases are central to material,\nbiological and bio-inspired systems. Despite their fundamental and applied\nsignificance, a detailed understanding of the stationary behaviour of nematic\nliquid crystals (NLC-s) in cylindrical capillaries is still lacking. Here,\nusing numerical simulations based on the continuum theory of Leslie, Ericksen\nand Parodi, we investigate stationary NLC flows within cylindrical capillaries\npossessing homeotropic (normal) and uniform planar anchoring conditions. By\nconsidering the material parameters of the flow-aligning NLC, 5CB, we report\nthat instead of the expected, unique director field monotonically approaching\nthe alignment angle over corresponding Ericksen numbers (dimensionless number\ncapturing viscous v/s elastic effects), a second solution emerges below a\nthreshold flow rate (or applied pressure gradient). We demonstrate that the\nonset of the second solution, a nematodynamic bifurcation yielding\nenergetically degenerate director tilts at the threshold pressure gradient, can\nbe controlled by the surface anchoring and the flow driving mechanism\n(pressure-driven or volume-driven). For homeotropic surface anchoring, this\nalternate director field orients against the alignment angle in the vicinity of\nthe capillary center; while in the uniform planar case, the alternate director\nfield extends throughout the capillary volume, leading to reduction of the flow\nspeed with increasing pressure gradients. While the practical realization and\nutilization of such nematodynamic bifurcations still await systematic\nexploration, signatures of the emergent rheology have been reported previously\nwithin microfluidic environments, under both homeotropic (Sengupta et al.,\nPhys. Rev. Lett. 110, 048303, 2013) and planar anchoring conditions (Sengupta,\nInt. J. Mol. Sci. 14, 22826, 2013)."
    },
    {
        "anchor": "An introduction to the colloidal glass transition: Colloids are suspensions of small solid particles in a liquid, and exhibit\nglassy behavior when the particle concentration is high. In these samples, the\nparticles are roughly analogous to individual molecules in a traditional glass.\nThis model system has been used to study the glass transition since the 1980's.\nIn this Viewpoint we summarize some of the intriguing behaviors of the glass\ntransition in colloids, and discuss open questions.",
        "positive": "Activation energy spectrum for relaxation and polyamorphism in an\n  ultra-viscous metallic glass former: Many glass-formers exhibit phase transitions between two distinct liquid\nstates. For some metallic glass-formers, the liquid-liquid transition is\nexperimentally found in the supercooled liquid at intermediate temperature\nbetween the melting point and the glass transition temperature Tg. We report\nhere on a liquid-liquid transition in an ultra-viscous metallic glass-former,\naccessed during long-time annealing. This study is conducted on the\nAu49Cu26.9Si16.3Ag5.5Pd2.3 composition with a liquid-liquid transition\ntemperature slightly lower than Tg. The consequence is that the\nhigh-temperature kinetically fragile liquid freezes into the glass during\nconventional processing and the underlying liquid-liquid transition is thus\naccessed by the system during annealing below Tg. Upon reheating, the reverse\ntransformation is observed by calorimetry. This conclusion is supported by a\nbroad collection of complementary laboratory and synchrotron-based techniques,\nsuch as differential- and fast- scanning calorimetry, and x-ray photon\ncorrelation spectroscopy. Our findings support the big-picture proposed by\nAngell that liquids with different fragility occupy different flanks of an\nunderlying order-disorder transition. Furthermore, our multiscale analysis\nreveals the existence of multiple decays of the enthalpy recovery, which is\nreflected in the observed microscopic ordering and aging mechanism of the glass\nthrough distinct stationary regimes interconnected by abrupt dynamical aging\nregimes."
    },
    {
        "anchor": "Adaptation of Autocatalytic Fluctuations to Diffusive Noise: Evolution of a system of diffusing and proliferating mortal reactants is\nanalyzed in the presence of randomly moving catalysts. While the continuum\ndescription of the problem predicts reactant extinction as the average growth\nrate becomes negative, growth rate fluctuations induced by the discrete nature\nof the agents are shown to allow for an active phase, where reactants\nproliferate as their spatial configuration adapts to the fluctuations of the\ncatalysts density. The model is explored by employing field theoretical\ntechniques, numerical simulations and strong coupling analysis. For d<=2, the\nsystem is shown to exhibits an active phase at any growth rate, while for d>2 a\nkinetic phase transition is predicted. The applicability of this model as a\nprototype for a host of phenomena which exhibit self organization is discussed.",
        "positive": "Dynamics of end to end loop formation for an isolated chain in\n  viscoelastic fluid: We theoretically investigate the looping dynamics of a linear polymer\nimmersed in a viscoelastic fluid. The dynamics of the chain is governed by a\nRouse model with a fractional memory kernel recently proposed by Weber et al.\n(S. C. Weber, J. A. Theriot, and A. J. Spakowitz, Phys. Rev. E 82, 011913\n(2010)). Using the Wilemski-Fixman (G. Wilemski and M. Fixman, J. Chem. Phys.\n60, 866 (1974)) formalism we calculate the looping time for a chain in a\nviscoelastic fluid where the mean square displacement of the center of mass of\nthe chain scales as t^(1/2). We observe that the looping time is faster for the\nchain in viscoelastic fluid than for a Rouse chain in Newtonian fluid up to a\nchain length and above this chain length the trend is reversed. Also no scaling\nof the looping time with the length of the chain seems to exist for the chain\nin viscoelastic fluid."
    },
    {
        "anchor": "Rheology of athermal amorphous solids: Revisiting simplified scenarios\n  and the concept of mechanical noise temperature: We study the rheology of amorphous solids in the limit of negligible thermal\nfluctuations. On the basis of general arguments, the flow curve is shown to\nresult from an interplay between the time scales of the macroscopic driving and\nthe (cascades of) local particle rearrangements. Such rearrangements are known\nto induce a redistribution of the elastic stress in the system. Although\nmechanical noise, i.e., the local stress fluctuations arising from this\nredistribution, is widely believed to activate new particle rearrangements, we\nprovide evidence that casts severe doubt on the analogy with thermal\nfluctuations: mechanical and thermal fluctuations lead to asymptotically\ndifferent statistics for barrier crossing. These ideas are illustrated and\nsupported by a simple coarse-grained model whose ingredients are directly\nconnected with the physical processes relevant for the flow.",
        "positive": "Osmosis, colligative properties, entropy, free energy and the chemical\n  potential: A diffusive model of osmosis is presented that explains currently available\nexperimental data. It makes predictions that distinguish it from the\ntraditional convective flow model of osmosis, some of which have already been\nconfirmed experimentally and others have yet to be tested. It also provides a\nsimple kinetic explanation of Raoult's law and the colligative properties of\ndilute aqueous solutions. The diffusive model explains that when a water\nmolecule jumps from low to high osmolarity at equilibrium, the free energy\nchange is zero because the work done pressurizing the water molecule is\nbalanced by the entropy of mixing. It also explains that equal chemical\npotentials are required for particle exchange equilibrium in analogy with the\nfamiliar requirement of equal temperatures at thermal equilibrium."
    },
    {
        "anchor": "Braided Bundles and Compact Coils: The Structure and Thermodynamics of\n  Hexagonally-Packed, Chiral Filament Assemblies: Molecular chirality frustrates the two-dimensional assembly of filamentous\nmolecules, a fact that reflects the generic impossibility of imposing a global\ntwisting of layered materials. We explore the consequences of this frustration\nfor hexagonally-ordered assemblies of chiral filaments that are {\\it finite} in\nlateral dimension. Specifically, we employ a continuum-elastic description of\ncylindrical bundles of filaments, allowing us to consider the most general\nresistance to and preference for chiral ordering of the assembly. We explore\ntwo distinct mechanisms by which chirality at the molecular scale of the\nfilament frustrates the assembly into aggregates. In the first, chiral\ninteractions between filaments impart an overall twisting of filaments around\nthe central axis of the bundle. In the second, we consider filaments that are\ninherently helical in structure, imparting a writhing geometry to the central\naxis. For both mechanisms, we find that a thermodynamically-stable state of\ndispersed bundles of {\\it finite} width appears close to, but below, the point\nof bulk filament condensation. The range of thermodynamic stability of\ndispersed bundles is sensitive only to the elastic cost and preference for\nchiral filament packing. The self-limited assembly of chiral filaments has\nparticular implications for a large class of biological molecules -- DNA,\nfilamentous proteins, viruses, bacterial flagella -- which are universally\nchiral and are observed to form compact bundles under a broad range of\nconditions.",
        "positive": "Furrows in the wake of propagating d-cones: We investigate the formation dynamics of plastic creases in thin\nelasto-plastic sheets. In contrast to the commonly accepted description of\ncrumpled thin sheets, which asserts that creases form only by elastic\ninteraction between two d-cones, the creases we study in this letter are\ncreated by plastic deformations left in the wake of a single propagating\nd-cone. Upon application of load, a d-cone initially remains stationary and\nresponds by deforming globally. However, above a critical load, the d-cone\nundergoes a sharpening transition that focuses the stresses at its tip,\nallowing it to propagate along the sheet, leaving a furrow-like scar in its\nwake. Our results show that the dynamics of plastic defect creation are\nimportant for predicting the final geometry and statistics of a defect network\nin a crumpled thin sheet."
    },
    {
        "anchor": "Coarse graining of master equations with fast and slow states: We propose a general method for simplifying master equations by eliminating\nfrom the description rapidly evolving states. The physical recipe we impose is\nthe suppression of these states and a renormalization of the rates of all the\nsurviving states. In some cases, this decimation procedure can be analytically\ncarried out and is consistent with other analytical approaches, like in the\nproblem of the random walk in a double-well potential. We discuss the\napplication of our method to nontrivial examples: diffusion in a lattice with\ndefects and a model of an enzymatic reaction outside the steady state regime.",
        "positive": "Quantitative reintepretation of quartz-crystal-microbalance experiments\n  with adsorbed particles using analytical hydrodynamics: Despite being a fundamental tool in soft matter research, quartz crystal\nmicrobalance (QCM) analyses of discrete macromolecules in liquid so far lack a\nfirm theoretical basis. Currently, acoustic signals are qualitatively\ninterpreted using ad-hoc frameworks based on effective electrical circuits,\neffective springs and trapped-solvent models with abundant fitting parameters.\nNevertheless, due to its extreme sensitivity, the QCM technique pledges to\nbecome an accurate predictive tool. Using unsteady low Reynolds hydrodynamics\nwe derive analytical expressions for the acoustic impedance of adsorbed\ndiscrete spheres. Our theory is successfully validated against 3D simulations\nand a plethora of experimental results covering more than a decade of research\non proteins, viruses, liposomes, massive nanoparticles, with sizes ranging from\nfew to hundreds of nanometers. The excellent agreement without fitting\nconstants clearly indicates that the acoustic response is dominated by the\nhydrodynamic impedance, thus, deciphering the secondary contribution of\nphysico-chemical forces will first require a hydrodynamic-reinterpretation of\nQCM."
    },
    {
        "anchor": "Polydispersity stabilizes Biaxial Nematic Liquid Crystals: Inspired by the observations of a remarkably stable biaxial nematic phase\n[E.v.d. Pol et al., Phys. Rev. Lett. 103, 258301 (2009)], we investigate the\neffect of size polydispersity on the phase behavior of a suspension of\nboardlike particles. By means of Onsager theory within the restricted\norientation (Zwanzig) model we show that polydispersity induces a novel\ntopology in the phase diagram, with two Landau tetracritical points in between\nwhich oblate uniaxial nematic order is favored over the expected prolate order.\nAdditionally, this phenomenon causes the opening of a huge stable biaxiality\nregime in between uniaxial nematic and smectic states.",
        "positive": "Wrinkling and developable cones in centrally confined sheets: Thin sheets respond to confinement by smoothly wrinkling, or by focusing\nstress into small, sharp regions. From engineering to biology, geology,\ntextiles, and art, thin sheets are packed and confined in a wide variety of\nways, and yet fundamental questions remain about how stresses focus and\npatterns form in these structures. Using experiments and molecular dynamics\n(MD) simulations, we probe the confinement response of circular sheets,\nflattened in their central region and quasi-statically drawn through a ring.\nWrinkles develop in the outer, free region, then are replaced by a truncated\ncone, which forms in an abrupt transition to stress focusing. We explore how\nthe force associated with this event, and the number of wrinkles, depend on\ngeometry. Additional cones sequentially pattern the sheet, until axisymmetry is\nrecovered in most geometries. The cone size is sensitive to in-plane geometry.\nWe uncover a coarse-grained description of this geometric dependence, which\ndiverges depending on the proximity to the asymptotic d-cone limit, where the\nclamp size approaches zero. This work contributes to the characterization of\ngeneral confinement of thin sheets, while broadening the understanding of the\nd-cone, a fundamental element of stress focusing, as it appears in realistic\nsettings."
    },
    {
        "anchor": "From yielding to shear jamming in a cohesive frictional suspension: Simulations are used to study the steady shear rheology of dense suspensions\nof frictional particles exhibiting discontinuous shear thickening and shear\njamming, in which finite-range cohesive interactions result in a yield stress.\nWe develop a constitutive model that combines yielding behavior and shear\nthinning at low stress with the frictional shear thickening at high stresses,\nin good agreement with the simulation results. This work shows that there is a\ndistinct difference between solids below the yield stress and in the\nshear-jammed state, as the two occur at widely separated stress levels,\nseparated by a region of stress in which the material is flowable.",
        "positive": "Granular segregation as a critical phenomenon: We present the results of an experimental study of patterned segregation in a\nhorizontally shaken shallow layer of a binary mixture of dry particles. An\norder parameter for the segregated structures is defined and the effect of the\nvariation of the combined filling fraction, $C$, of the mixture on the observed\npattern formation is systematically studied. The surprising result is that\nthere is a critical event associated with the onset of the pattern, at\n$C=0.647\\pm0.049$, which has the characteristics of a second order phase\ntransition, including critical slowing down."
    },
    {
        "anchor": "Elastic Rayleigh-Plateau instability: Dynamical selection of nonlinear\n  states: A slender thread of elastic hydrogel is susceptible to a surface instability\nthat is reminiscent of the classical Rayleigh-Plateau instability of liquid\njets. The final, highly nonlinear states that are observed in experiments arise\nfrom a competition between capillarity and large elastic deformations.\nCombining a slender analysis and fully three-dimensional numerical simulations,\nwe present the phase map of all possible morphologies for an unstable\nneo-Hookean cylinder subjected to capillary forces. Interestingly, for softer\ncylinders we find the coexistence of two distinct configurations, namely,\ncylinders-on-a-string and beads-on-a-string. It is shown that for a given set\nof parameters, the final pattern is selected via a dynamical evolution. To\ncapture this, we compute the dispersion relation and determine the\ncharacteristic wavelength of the dynamically selected profiles. The validity of\nthe \"slender\" results is confirmed via simulations and these results are\nconsistent with experiments on elastic and viscoelastic threads.",
        "positive": "Modification of the fluctuation dynamics of ultra-thin wetting films: We report on the effect of intermolecular forces on the fluctuations of\nsupported liquid films. Using an optically-induced thermal gradient, we form\nnanometer-thin films of wetting liquids on glass substrates, where van der\nWaals forces are balanced by thermocapillary forces. We show that the\nfluctuation dynamics of the film interface is strongly modified by\nintermolecular forces at lower frequencies. Data spanning three frequency\ndecades are in excellent agreement with theoretical predictions accounting for\nvan der Waals forces. Our results emphasize the relevance of intermolecular\nforces on thermal fluctuations when fluids are confined at the nanoscale."
    },
    {
        "anchor": "Quantum Chemical Analysis of the Excited State Dynamics of Hydrated\n  Electrons: Quantum calculations are performed for an anion water cluster representing\nthe first hydration shell of the solvated electron in solution. The absorption\nspectra from the ground state, the instant excited states and the relaxed\nexcited states are calculated including CI-SD interactions. Analytic\nexpressions for the nonadiabatic relaxation are presented. It is shown that the\n50fs dynamics recently observed after s->p excitation is best accounted for if\nit is identified with the internal conversion, preceded by an adiabatic\nrelaxation within the excited p state. In addition, transient absorptions found\nin the infrared are qualitatively reproduced by these calculations .",
        "positive": "Pair interactions between complex mesoscopic particles from Widom's\n  particle-insertion method: We demonstrate that Widom's particle insertion technique provides a\nconvenient and efficient method to determine the effective pair interaction\nbetween complex, composite soft-matter particles in the zero-density limit. By\nmeans of three different test systems, i.e. amphiphilic dendrimers,\nelectrostatic polymers and colloids coated with electrostatic polymers, we\ndemonstrate the validity and the power of the presented method."
    },
    {
        "anchor": "Physics of Smart Matter: integrating active matter and control to gain\n  insights into living systems: We offer our opinion on the benefits of integration of insights from active\nmatter physics with principles of regulatory interactions and control to\ndevelop a field we term ``smart matter\". This field can provide insight into\nimportant principles in living systems as well as aid engineering of\nresponsive, robust and functional collectives.",
        "positive": "Statistical Mechanics of DNA Rupture: Theory and Simulations: We study the effects of the shear force on the rupture mechanism on a double\nstranded DNA. Motivated by recent experiments, we perform the atomistic\nsimulations with explicit solvent to obtain the distributions of extension in\nhydrogen and covalent bonds below the rupture force. We obtain a significant\ndifference between the atomistic simulations and the existing results in the\niterature based on the coarse-grained models (theory and simulations). We\ndiscuss the possible reasons and improve the coarse-grained model by\nincorporating the consequences of semi-microscopic details of the nucleotides\nin its description. The distributions obtained by the modified model\n(simulations and theoretical) are qualitatively similar to the one obtained\nusing atomistic simulations."
    },
    {
        "anchor": "Collective dynamics and pair-distribution function of active Brownian\n  ellipsoids: While the collective dynamics of spherical active Brownian particles is\nrelatively well understood by now, the much more complex dynamics of\nnonspherical active particles still raises interesting open questions. Previous\nwork has shown that the dynamics of rod-like or ellipsoidal active particles\ncan differ significantly from that of spherical ones. Here, we obtain the full\nstate diagram of active Brownian ellipsoids depending on the P\\'eclet number\nand packing density via computer simulations. The system is found to exhibit a\nrich state behavior that includes cluster formation, local polar order, polar\nflocks, and disordered states. Moreover, we obtain numerical results and an\nanalytical representation for the pair-distribution function of active\nellipsoids. This function provides useful quantitative insights into the\ncollective behavior of active particles with lower symmetry and has potential\napplications in the development of predictive theoretical models.",
        "positive": "Molecular Dynamics Simulations of Anisotropic Particles Accelerated by\n  Neural-Net Predicted Interactions: Rigid bodies, made of smaller composite beads, are commonly used to simulate\nanisotropic particles with molecular dynamics or Monte Carlo methods. To\naccurately represent the particle shape and to obtain smooth and realistic\neffective pair interactions between two rigid bodies, each body may need to\ncontain hundreds of spherical beads. Given an interacting pair of particles,\ntraditional MD methods calculate the inter-body distances between the beads of\nthe rigid bodies within a certain distance. For a system containing many\nanisotropic particles, distance calculations are computationally costly and\nlimit the attainable system size and simulation time. However, the effective\ninteraction between two rigid particles only depends on the distance between\ntheir center of masses and their relative orientation. Therefore, a function\ndirectly mapping the center of mass distance and orientation to the interaction\nenergy between the two rigid bodies, would completely bypass inter-bead\ndistance calculations. It is challenging to derive such a general function\nanalytically for most non-spherical rigid bodies. We have trained neural nets,\npowerful tools to fit nonlinear functions to complex datasets, to achieve this\ntask. The pair configuration is taken as input and the energy, forces and\ntorques between two rigid particles are predicted directly. We show that MD\nsimulations of cubes and cylinders performed with forces and torques obtained\nfrom the gradients of the energy neural-nets quantitatively match traditional\nsimulations that uses composite rigid bodies. Both structural quantities and\ndynamic measures are in agreement, while achieving up to 23 times speed up over\ntraditional molecular dynamics, depending on hardware and system size. The\nmethod can, in principle, be applied to any irregular shape with any pair\ninteraction, provided that sufficient training data can be obtained."
    },
    {
        "anchor": "Active Caustics: Heavy particles in vortical fluid flow cluster strongly, forming singular\nstructures termed caustics for their resemblance to focal surfaces in optics.\nWe show here that such extreme aggregation onto low-dimensional submanifolds\ncan arise without inertia for self-propelled particles (SPPs). We establish\nthat a singular perturbation is at the heart of caustic formation by SPPs\naround a single vortex, and our numerical studies of SPPs in two-dimensional\nNavier-Stokes turbulence shows intense caustics in the straining regions of the\nflow, peaking at intermediate levels of self-propulsion. Our work offers a\nroute to singularly high local concentrations in a macroscopically dilute\nsuspension of zero-Reynolds number swimmers, with potentially game-changing\nimplications for communication and sexual reproduction. An intriguing open\ndirection is whether the active turbulence of a suspension of swimming microbes\ncould serve to generate caustics in its own concentration.",
        "positive": "Liquid-state theory of charged colloids: A simple theory of the fluid state of a charged colloidal suspension is\nproposed. The full free energy of a polyelectrolyte solution is calculated. It\nis found that the counterions condense onto the polyions forming clusters\ncomposed of one polyion and n counterions. The distribution of cluster sizes is\ndetermined explicitly. In agreement with the current experimental and Monte\nCarlo results, no liquid-gas phase separation was encountered."
    },
    {
        "anchor": "Molecular Tilt on Monolayer-Protected Nanoparticles: The structure of the tilted phase of monolayer-protected nanoparticles is\ninvestigated by means of a simple Ginzburg-Landau model. The theory contains\ntwo dimensionless parameters representing the preferential tilt angle and the\nratio epsilon between the energy cost due to spatial variations in the tilt of\nthe coating molecules and that of the van der Waals interactions which favors\nuniform tilt. We analyze the model for both spherical and octahedral particles.\nOn spherical particles, we find a transition from a tilted phase, at small\nepsilon, to a phase where the molecules spontaneously align along the surface\nnormal and tilt disappears. Octahedral particles have an additional phase at\nsmall epsilon characterized by the presence of six topological defects. These\ndefective configurations provide preferred sites for the chemical\nfunctionalization of monolayer-protected nanoparticles via place-exchange\nreactions and their consequent linking to form molecules and bulk materials.",
        "positive": "Mapping diffusivity of narrow channels into one-dimension: The diffusion of particles trapped in long narrow channels occurs\npredominantly in one dimension. Here, molecular dynamics simulation is used to\nstudy the inertial dynamics of two-dimensional hard disks, confined to long,\nnarrow, structureless channels with hard walls in the no-passing regime. We\nshow that the diffusion coefficient obtained from the mean squared displacement\ncan be mapped onto the exact results for the diffusion of the strictly\none-dimensional hard rod system through an effective occupied volume fraction\nobtained from either the equation of state or a geometric projection of the\nparticle interaction diameters."
    },
    {
        "anchor": "Surface roughness induced electric field enhancement and\n  triboluminescence: The separation of solids in adhesive contact, or the fracture of solid\nbodies, often results in the emission of high energy photons, e.g., visible\nlight and X-rays. This is believed to be related to charge separation. We\npropose that the emission of high energy photons involves surface roughness and\nsurface diffusion of ions or electrons, resulting in the concentration of\ncharge at the tips of high asperities, and to electric field enhancement, which\nfacilitate the discharging process which result in the high energy photons. If\nthe surface diffusion is too fast, or the separation of the solid surfaces too\nslow, discharging start at small interfacial separation resulting in low energy\nphotons.",
        "positive": "Deriving fundamental measure theory from the virial series: Consistency\n  with the zero-dimensional limit: Fundamental measure theory (FMT) for hard particles has great potential for\npredicting the phase behavior of colloidal and nanometric shapes. The modern\nversions of FMT are usually derived from the zero-dimensional limit, a system\nof at most one particle confined in a collection of cavities in the limit that\nall cavities shrink to the size of the particle. In [Phys. Rev. E 85, 041150\n(2012)], a derivation from an approximated and resummed virial expansion was\npresented, whose result was not fully consistent with the FMT from the\nzero-dimensional limit. Here we improve upon this derivation and obtaining\nexactly the same FMT functional as was obtained earlier from the\nzero-dimensional limit. As a result, further improvements of FMT based on the\nvirial expansion can now be formulated, some of which we suggest in the\noutlook."
    },
    {
        "anchor": "Hydrodynamic correlations in isotropic fluids and liquid crystals\n  simulated by multi-particle collision dynamics: Multi-particle collision dynamics is an appealing numerical technique aiming\nat simulating fluids at the mesoscopic scale. It considers molecular details in\na coarse-grained fashion and reproduces hydrodynamic phenomena. Here, the\nimplementation of multi-particle collision dynamics for isotropic fluids is\nanalysed under the so-called Andersen-thermostatted scheme, a particular\nalgorithm for systems in the canonical ensemble. This method gives rise to\nhydrodynamic fluctuations that spontaneously relax towards equilibrium. This\nrelaxation process can be described by a linearized theory and used to\ncalculate transport coefficients of the system. The extension of the algorithm\nfor nematic liquid crystals is also considered. It is shown that thermal\nfluctuations in the average molecular orientation can be described by an\nextended linearized scheme. Flow fluctuations induce orientation fluctuations.\nHowever, orientational changes produce observable effects on velocity\ncorrelation functions only when simulation parameters exceed their values from\nthose used in previous applications of the method. Otherwise, the flow can be\nconsidered to be independent of the orientation field.",
        "positive": "Regularization methods for finding the relaxation time spectra of linear\n  polydisperse polymer melts: The calculation of discrete or continuous relaxation time spectra from\nrheometric measurables of polydisperse polymers is an ill-posed problem. In\nthis paper, a curve fitting method for solving this problem is presented and\ncompared to selected models from the literature. It is shown that the new\nmethod is capable of correctly predicting the molecular mass distributions of\nlinear polydisperse polymer melts as well as their relaxation time spectra."
    },
    {
        "anchor": "The Topology of Dislocations in Smectic Liquid Crystals: The order parameter of the smectic liquid crystal phase is the same as that\nof a superfluid or superconductor, namely a complex scalar field. We show that\nthe essential difference in boundary conditions between these systems leads to\na markedly different topological structure of the defects. Screw and edge\ndefects can be distinguished topologically. This implies an invariant on an\nedge dislocation loop so that smectic defects can be topologically linked not\nunlike defects in ordered systems with non-Abelian fundamental groups.",
        "positive": "Protocol-Dependence and State Variables in the Force-Moment Ensemble: Stress-based ensembles incorporating temperature-like variables have been\nproposed as a route to an equation of state for granular materials. To test the\nefficacy of this approach, we perform experiments on a two-dimensional\nphotoelastic granular system under three loading conditions: uniaxial\ncompression, biaxial compression, and simple shear. From the interparticle\nforces, we find that the distributions of the normal component of the\ncoarse-grained force-moment tensor are exponential-tailed, while the deviatoric\ncomponent is Gaussian-distributed. This implies that the correct stress-based\nstatistical mechanics conserves both the force-moment tensor and the\nMaxwell-Cremona force-tiling area. As such, two variables of state arise: the\ntensorial angoricity ($\\hat{\\alpha}$) and a new temperature-like quantity\nassociated with the force-tile area which we name {\\it keramicity} ($\\kappa$).\nEach quantity is observed to be inversely proportional to the global confining\npressure; however only $\\kappa$ exhibits the protocol-independence expected of\na state variable, while $\\hat{\\alpha}$ behaves as a variable of process."
    },
    {
        "anchor": "Signature of a non-harmonic potential as revealed from a consistent\n  shape and fluctuation analysis of an adherent membrane: The interaction of fluid membranes with a scaffold, which can be a planar\nsurface or a more complex structure, is intrinsic to a number of systems - from\nartificial supported bilayers and vesicles to cellular membranes. In principle,\nthese interactions can be either discrete and protein mediated, or continuous.\nIn the latter case, they emerge from ubiquitous intrinsic surface interaction\npotentials as well as nature-designed steric contributions of the fluctuating\nmembrane or from the polymers of the glycocalyx. Despite the fact that these\nnonspecific potentials are omnipresent, their description has been a major\nchallenge from experimental and theoretical points of view. Here we show that a\nfull understanding of the implications of the continuous interactions can be\nachieved only by expanding the standard superposition models commonly used to\ntreat these types of systems, beyond the usual harmonic level of description.\nSupported by this expanded theoretical framework, we present three independent,\nyet mutually consistent, experimental approaches to measure the interaction\npotential strength and the membrane tension. Upon explicitly taking into\naccount the nature of shot noise as well as of finite experimental resolution,\nexcellent agreement with the augmented theory is obtained, which finally\nprovides a coherent view of the behavior of the membrane in a vicinity of a\nscaffold.",
        "positive": "Dynamical Eigenmodes of Star and Tadpole Polymers: The dynamics of phantom bead-spring chains with the topology of a symmetric\nstar with $f$ arms and tadpoles ($f=3$, a special case) is studied, in the\noverdamped limit. In the simplified case where the hydrodynamic radius of the\ncentral monomer is $f$ times as heavy as the other beads, we determine their\ndynamical eigenmodes exactly, along the lines of the Rouse modes for linear\nbead-spring chains. These eigenmodes allow full analytical calculations of\nvirtually any dynamical quantity. As examples we determine the radius of\ngyration, the mean square displacement of a tagged monomer, and, for star\npolymers, the autocorrelation function of the vector that spans from the center\nof the star to a bead on one of the arms."
    },
    {
        "anchor": "Freezing a Flock: Motility-Induced Phase Separation in Polar Active\n  Liquids: Combining model experiments and theory, we investigate the dense phases of\npolar active matter beyond the conventional flocking picture. We show that\nabove a critical density flocks assembled from self-propelled colloids arrest\ntheir collective motion, lose their orientational order and form solids that\nactively rearrange their local structure while continuously melting and\nfreezing at their boundaries. We establish that active solidification is a\nfirst-order dynamical transition: active solids nucleate, grow, and slowly\ncoarsen until complete phase separation with the polar liquids they coexists\nwith. We then theoretically elucidate this phase behaviour by introducing a\nminimal hydrodynamic description of dense polar flocks and show that the active\nsolids originate from a Motility-Induced Phase Separation. We argue that the\nsuppression of collective motion in the form of solid jams is a generic feature\nof flocks assembled from motile units that reduce their speed as density\nincreases, a feature common to a broad class of active bodies, from synthetic\ncolloids to living creatures.",
        "positive": "flippy: User friendly and open source framework for lipid membrane\n  simulations: Animal cells are both encapsulated and subdivided by lipid bilayer membranes.\nBeyond just acting as boundaries, these membranes' shapes influence the\nfunction of cells and their compartments. Physically, membranes are\ntwo-dimensional fluids with complex elastic behavior, which makes it\nimpossible, for all but a few simple cases, to predict membrane shapes\nanalytically. Instead, the shape and behavior of biological membranes can be\ndetermined by simulations. However, the setup and use of such simulations\nrequire a significant programming background. The availability of open-source\nand user-friendly packages for simulating biological membranes needs\nimprovement.Here, we present flippy, an open-source package for simulating\nlipid membrane shapes, their interaction with proteins or external particles,\nand the effect of external forces. Our goal is to provide a tool that is easy\nto use without sacrificing performance or versatility. flippy is an\nimplementation of a dynamically triangulated membrane. We use a precise yet\nfast algorithm for calculating the geometric properties of membranes and can\nalso account for local spontaneous curvature, a feature not all discretizations\nallow. Finally, in flippy we can also include regions of purely elastic\n(non-fluid) membranes and thus explore various shapes encountered in living\nsystems."
    },
    {
        "anchor": "Excluded volume effects in polymer brushes at moderate chain stretching: We develop a strong stretching approximation for a polymer brush made of\nself-avoiding polymer chains. The density profile of the brush and the\ndistribution of the end monomer positions in stretching direction are computed\nand compared with simulation data. We find that our approach leads to a clearly\nbetter approximation as compared to previous approaches based upon Gaussian\nelasticity at low grafting densities (moderate chain stretching), for which\ncorrections due to finite extensibility can be ignored.",
        "positive": "Quasiparticles, Flat Bands, and the Melting of Hydrodynamic Matter: The concept of quasiparticles -- long-lived low-energy particle-like\nexcitations -- has become a keystone of condensed quantum matter, where it\nexplains a variety of emergent many-body phenomena, such as superfluidity and\nsuperconductivity. Here, we use quasiparticles to explain the collective\nbehavior of a classical system of hydrodynamically interacting particles in two\ndimensions. In the disordered phase of this matter, measurements reveal a\nsub-population of long-lived particle pairs. Modeling and simulation of the\nordered crystalline phase identify the pairs as quasiparticles, emerging at the\nDirac cones of the spectrum. The quasiparticles stimulate supersonic pairing\navalanches, bringing about the melting of the crystal. In hexagonal crystals,\nwhere the intrinsic threefold symmetry of the hydrodynamic interaction matches\nthat of the crystal, the spectrum forms a flat band dense with ultra-slow,\nlow-frequency phonons whose collective interactions induce a much sharper\nmelting transition. Altogether, these findings demonstrate the usefulness of\nconcepts from quantum matter theory in understanding many-body physics in\nclassical dissipative settings."
    },
    {
        "anchor": "Continuous Time Random Walks and South Spain Seismic Series: Levy flights were introduced through the mathematical research of the algebra\nor random variables with infinite moments. Mandelbrot recognized that the Levy\nflight prescription had a deep connection to scale-invariant fractal random\nwalk trajectories. The theory of Continuous Time Random Walks (CTRW) can be\ndescribed in terms of Levy distribution functions and it can be used to explain\nsome earthquake characteristics like the distribution of waiting times and\nhypocenter locations in a seismic region. This paper checks the validity of\nthis assumption analyzing three seismic series localized in South Spain. The\nthree seismic series (Alboran, Antequera and Loja) show qualitatively the same\nbehavior, although there are quantitative differences between them.",
        "positive": "Unjamming of active rotators: Active particle assemblies can exhibit a wide range of interesting dynamical\nphases depending on internal parameters such as density, adhesion strength or\nself-propulsion. Active self-rotations are rarely studied in this context,\nalthough they can be relevant for active matter systems, as we illustrate by\nanalyzing the motion of Chlamydomonas reinhardtii algae under different\nexperimental conditions. Inspired by this example, we simulate the dynamics of\na system of interacting active disks endowed with active torques. At low\npacking fractions, adhesion causes the formation of small rotating clusters,\nresembling those observed when algae are stressed. At higher densities, the\nmodel shows a jamming to unjamming transition promoted by active torques and\nhindered by adhesion. Our results yield a comprehensive picture of the dynamics\nof active rotators, providing useful guidance to interpret experimental results\nin cellular systems where rotations might play a role."
    },
    {
        "anchor": "Supported lipid membranes with designed geometry: The membrane curvature of cells and intracellular compartments continuously\nadapts to enable cells to perform vital functions, from cell division to signal\ntrafficking. Understanding how membrane geometry affects these processes in\nvivo is challenging because of the membrane complexity as well as the short\ntime and small length scales involved. By contrast, in vitro model membranes\nwith engineered curvature provide a versatile platform for this investigation\nand applications to biosensing and biocomputing. However, a general route to\nthe fabrication of lipid membranes with prescribed curvature and high spatial\nresolution is still missing. Here, we present a strategy that overcomes these\nchallenges and achieve lipid membranes with designed shape by combining 3D\nmicro-printing and replica-molding lithography to create scaffolds with\nvirtually any geometry and high spatial resolution. The resulting supported\nlipid membranes are homogeneous, fluid, and can form chemically distinct lipid\ndomains. These features are essential for understanding curvature-dependent\ncellular processes and developing programmable bio-interfaces for living cells\nand nanostructures.",
        "positive": "Rate-dependent elastic hysteresis during the peeling of Pressure\n  Sensitive Adhesives: The modelling of the adherence energy during peeling of Pressure Sensitive\nAdhesives (PSA) has received much attention since the 1950's, uncovering\nseveral factors that aim at explaining their high adherence on most substrates,\nsuch as the softness and strong viscoelastic behaviour of the adhesive, the low\nthickness of the adhesive layer and its confinement by a rigid backing. The\nmore recent investigation of adhesives by probe-tack methods also revealed the\nimportance of cavitation and stringing mechanisms during debonding, underlining\nthe influence of large deformations and of the related non-linear response of\nthe material, which also intervenes during peeling. Although a global modelling\nof the complex coupling of all these ingredients remains a formidable issue, we\nreport here some key experiments and modelling arguments that should constitute\nan important step forward. We first measure a non-trivial dependence of the\nadherence energy on the loading geometry, namely through the influence of the\npeeling angle, which is found to be separable from the peeling velocity\ndependence. This is the first time to our knowledge that such adherence energy\ndependence on the peeling angle is systematically investigated and\nunambiguously demonstrated. Secondly, we reveal an independent strong influence\nof the large strain rheology of the adhesives on the adherence energy. We\ncomplete both measurements with a microscopic investigation of the debonding\nregion. We discuss existing modellings in light of these measurements and of\nrecent soft material mechanics arguments, to show that the adherence energy\nduring peeling of PSA should not be associated to the propagation of an\ninterfacial stress singularity. The relevant deformation mechanisms are\nactually located over the whole adhesive thickness, and the adherence energy\nduring peeling of PSA should rather be associated to the energy loss by viscous\nfriction and by rate-dependent elastic hysteresis."
    },
    {
        "anchor": "Chain Length Determines the Folding Rates of RNA: We show that the folding rates (k_F) of RNA are determined by N, the number\nof nucleotides. By assuming that the distribution of free energy barriers\nseparating the folded and the unfolded states is Gaussian, which follows from\ncentral limit theorem arguments and polymer physics concepts, we show that k_F\n~ k_0 exp(-alpha N^0.5). Remarkably, the theory fits the experimental rates\nspanning over seven orders of magnitude with k_0 ~ 1.0 (microsec)^{-1}. An\nimmediate consequence of our finding is that the speed limit of RNA folding is\nabout one microsecond just as it is in the folding of globular proteins.",
        "positive": "Reacting Polymers with Highly Correlated Initial Conditions: We propose and theoretically study an experiment designed to measure short\ntime polymer reaction kinetics in melts or dilute solutions. The photolysis of\ngroups centrally located along chain backbones, one group per chain, creates\npairs of spatially highly correlated macroradicals. We calculate time-dependent\nrate coefficients $\\kappa(t)$ governing their first order recombination\nkinetics, which are novel on account of the far-from-equilibrium initial\nconditions. In dilute solutions (good solvents) reaction kinetics are\nintrinsically weak, despite the highly reactive radical groups involved. This\nleads to a generalised mean field kinetics in which the rate of radical density\ndecay $-\\ndot \\twid S(t)$ where $S(t)\\twid t^{-(1+g/3)}$ is the {\\em\nequilibrium} return probability for 2 reactive groups, given initial contact.\nHere $g\\approx 0.27$ is the correlation hole exponent for self-avoiding chain\nends. For times beyond the longest coil relaxation time $\\tau$, $-\\ndot \\twid\nS(t)$ remains true, but center of gravity coil diffusion takes over with rms\ndisplacement of reactive groups $x(t)\\twid t^{1/2}$ and $S(t)\\twid 1/x^3(t)$.\nAt the shortest times ($t\\lsim 10^{-6}$ sec), recombination is inhibited due to\nspin selection rules and we find $\\ndot \\twid t S(t)$. In melts, kinetics are\nintrinsically diffusion-controlled, leading to entirely different rate laws.\nDuring the regime limited by spin selection rules, the density of radicals\ndecays linearly, $n(0)-n(t)\\twid t$. At longer times the standard result\n$-\\ndot\\twid dx^3(t)/dt$ (for randomly distributed ends) is replaced by\n$\\ndot\\twid d^2x^3(t)/dt^2$ for these correlated initial conditions. The long\ntime behavior, $t>\\tau$, has the same scaling form in time as for dilute\nsolutions."
    },
    {
        "anchor": "A tensor model for nematic phases of bent-core molecules based on\n  molecular theory: We construct a tensor model for nematic phases of bent-core molecules from\nmolecular theory. The form of free energy is determined by molecular symmetry,\nwhich includes the couplings and derivatives of a vector and two second-order\ntensors, with the coefficients determined by molecular parameters. We use the\nmodel to study the nematic phases resulted from the hard-core potential. Unlike\nmost macroscopic models, we are able to obtain the phase diagram about the\nmolecular parameters, but not merely some phenomenological coefficients. The\ntensor model is applicable to other molecules with the same symmetry, which we\ndemonstrate by studying the phase diagram of star molecules.",
        "positive": "Electrical conductance of two-dimensional composites with embedded\n  rodlike fillers: an analytical consideration and comparison of two\n  computational approaches: Using Monte Carlo simulation, we studied the electrical conductance of\ntwo-dimensional films. The films consisted of a poorly conductive host matrix\nand highly conductive rodlike fillers (rods). The rods were of various lengths,\nobeying a log-normal distribution. They were allowed to be aligned along a\ngiven direction. The impacts of length dispersity and the extent of rod\nalignment on the insulator-to-conductor phase transition were studied. Two\nalternative computational approaches were compared. Within Model I, the films\nwere transformed into resistor networks with regular structures and randomly\ndistributed conductances. Within Model II, the films were transformed into\nresistor networks with irregular structures but with equal conductivities of\nthe conductors. Comparison of the models evidenced similar behavior in both\nmodels when the concentration of fillers exceeded the percolation threshold.\nSome analytical results were obtained: (i) the relationship between the number\nof fillers per unit area and the transmittance of the film within Model I, (ii)\nthe electrical conductance of the film for dense networks within Model II."
    },
    {
        "anchor": "Screening of a macroion by multivalent ions: Correlation induced\n  inversion of charge: Screening of a strongly charged macroion by multivalent counterions is\nconsidered. It is shown that counterions form a strongly correlated liquid at\nthe surface of the macroion. Cohesive energy of this liquid leads to additional\nattraction of counterions to the surface which is absent in conventional\nsolutions of Poisson-Boltzmann equation. Away from the surface this attraction\ncan be taken into account by a new boundary condition for the concentration of\ncounterions near the surface. Poisson-Boltzmann equation is solved with this\nboundary condition for a charged flat surface, a cylinder and a sphere. In all\nthree cases, screening is much stronger than in the conventional approach. At\nsome critical exponentially small concentration of multivalent counterions in\nthe solution they totally neutralize the surface charge at small distances from\nthe surface. At larger concentrations they invert the sign the net macroion\ncharge. Absolute value of the inverted charge density can be as large as 20% of\nthat of the bare one. In particular, for a cylindrical macroion, it is shown\nthat for screening by multivalent counterions predictions of the\nOnsager-Manning theory are quantitatively incorrect. The net charge density of\nthe cylinder is smaller than their theory predicts and inverts sign with\ngrowing concentration of counterions. Moreover the condensation looses its\nuniversality and the net charge linear density depends on the bare one.",
        "positive": "Stripes ordering in self-stratification experiments of binary and\n  ternary granular mixtures: The self-stratification of binary and ternary granular mixtures has been\nexperimentally investigated. Ternary mixtures lead to a particular ordering of\nthe strates which was not accounted for in former explanations. Bouncing grains\nare found to have an important effect on strate formation. A complementary\nmechanism for self-stratification of binary and ternary granular mixtures is\nproposed."
    },
    {
        "anchor": "The study of uniaxial-biaxial phase transition of confined hard\n  ellipsoids using density functional theory: The density profiles and corresponding order parameters of the hard\nellipsoids confined between two hard walls and also in contact with a single\nhard wall are studied using the density functional theory. The Hyper-Netted\nChain (HNC) approximation is used to write excess grand potential of the system\nwith respect to the bulk value. To simplify the calculations we use restricted\norientation model (ROM) for the orientation of ellipsoids to find the density\nprofiles and order parameters. Density functional theory shows that there is a\nuniaxial-biaxial phase transition near a single hard wall and also between two\nhard walls for a fluid consisting of uniaxial hard ellipsoidal particles with\nfinite elongation.",
        "positive": "Line defects in nematic liquid crystals as charged superelastic rods\n  with negative twist--stretch coupling: Topological defects are a ubiquitous phenomenon in diverse physical systems.\nIn nematic liquid crystals (LCs), they are dynamic, physicochemically distinct,\nsensitive to stimuli, and are thereby promising for a range of applications.\nHowever, our current understanding of the mechanics and dynamics of defects in\nnematic LCs remain limited and are often overwhelmed by the intricate details\nof the specific systems. Here, we unify singular and nonsingular line defects\nas superelastic rods and combine theory, simulation, and experiment to\nquantitatively measure their effective elastic moduli, including line tension,\ntorsional rigidity, and twist--stretch coefficient. Interestingly, we found\nthat line defects exhibit a negative twist--stretch coupling, meaning that\ntwisted line defects tend to unwind under stretching, which is reminiscent of\nDNA molecules. A patterned nematic cell experiment further confirmed the above\nfindings. Taken together, we have established an effective elasticity theory\nfor nematic defects, paving the way towards understanding and engineering their\ndeformation and transformation in driven and active nematic materials."
    },
    {
        "anchor": "Breaking Chiral Symmetry with Microfluidics: A robust route for the biased production of single-handed chiral structures\nhas been found in generating non-spherical, multi-component double emulsions\nusing microfluidics. The specific type of handedness is determined by the final\npacking geometry of four different inner drops inside an ultra-thin sheath of\noil. Before three-dimensional chiral structures are formed, the\nquasi-one-dimensional chain re-arranges in two dimensions into either\ncheckerboard or stripe patterns. We derive an analytical model predicting which\npattern is more likely and assembles in the least amount of time. Moreover, our\ndimensionless model accurately predicts our experimental results and is based\non local bending dynamics, rather than global surface energy minimization. This\nbetter reflects the underlying self-assembly process which will not, in\ngeneral, reach a global energy minimum. In summary, using glass microfluidic\ntechniques for channeling aqueous fluids through narrow orifices of multi-bore\ninjection capillaries while encapsulating these fluids as drops inside an\nultra-thin sheath of oil is sufficient to produce single-handed chiral\nstructures.",
        "positive": "The nonlinear damping of Bose-Einstein condensate oscillations at\n  ultra-low temperatures: We analyze the damping of the transverse breathing mode in an elongated trap\nat ultralow temperatures. The damping occurs due to the parametric resonance\nentailing the energy transfer to the longitudinal degrees of freedom. It is\nfound that the nonlinear coupling between the transverse and discrete\nlongitudinal modes can result in an anomalous behavior of the damping as a\nfunction of time with the partially reversed pumping of the breathing mode. The\npicture revealed explains the results observed in [16]."
    },
    {
        "anchor": "Cross-interaction drives stratification in drying film of binary\n  colloidal mixtures: When a liquid film of colloidal solution consisting of particles of different\nsizes is dried on a substrate, the colloids often stratify, where smaller\ncolloids are laid upon larger colloids. This phenomenon is counter intuitive\nbecause larger colloids which have smaller diffusion constant are expected to\nremain near the surface during the drying process, leaving the layer of larger\ncolloids on top of smaller colloids. Here we show that the phenomenon is caused\nby the interaction between the colloids, and can be explained by the diffusion\nmodel which accounts for the interaction between the colloids. By studying the\nevolution equation both numerically and analytically, we derive the condition\nat which the stratified structures are obtained.",
        "positive": "Dynamic clustering in active colloidal suspensions with chemical\n  signaling: In this paper, we explore experimentally the phase behavior of a dense active\nsuspension of self- propelled colloids. In addition to a solid-like and a\ngas-like phase observed for high and low densities, a novel cluster phase is\nreported at intermediate densities. This takes the form of a stationary\nassembly of dense aggregates, with an average size which grows with activity as\na linear function of the self-propelling velocity. While different possible\nscenarii can be considered to account for these observations - such as a\ngeneric velocity weakening instability recently put forward -, we show that the\nexperimental results are reproduced by a chemotactic aggregation mechanism,\noriginally introduced to account for bacterial aggregation, and accounting here\nfor diffusiophoretic chemical interaction between colloidal swimmers."
    },
    {
        "anchor": "Theory of Sound Propagation in Superfluid Solutions Filled Porous Media: A theory of the propagation of acoustic waves in a porous medium filled with\nsuperfluid solution is developed. The elastic coefficients in the system of\nequations are expressed in terms of physically measurable quantities. The\nequations obtained describe all volume modes that can propagate in a porous\nmedium saturated with superfluid solution. Finally, derived equations are\napplied to the most important particular case when the normal fluid component\nis locked inside a highly porous media (aerogel) by viscous forces and the\nvelocities of two longitudinal sound modes are calculated.",
        "positive": "Dissolution-driven propulsion of floating solids: We show that unconstrained asymmetric dissolving solids floating in a fluid\ncan move rectilinearly as a result of attached density currents which occur\nalong their inclined surfaces. Solids in the form of boats composed of\ncentimeter-scale sugar and salt slabs attached to a buoy are observed to move\nrapidly in water with speeds up to 5 mm/s determined by the inclination angle\nand orientation of the dissolving surfaces. While symmetric boats drift slowly,\nasymmetric boats are observed to accelerate rapidly along a line before\nreaching a terminal velocity when their drag matches the thrust generated by\ndissolution. By visualizing the flow around the body, we show that the boat\nvelocity is always directed opposite to the horizontal component of the density\ncurrent. We derive the thrust acting on the body from its measured kinematics,\nand show that the propulsion mechanism is consistent with the unbalanced\nmomentum generated by the attached density current. We obtain an analytical\nformula for the body speed depending on geometry and material properties, and\nshow that it captures the observed trends reasonably. Our analysis shows that\nthe gravity current sets the scale of the body speed consistent with our\nobservations, and we estimate that speeds can grow slowly as the cube-root of\nthe length of the inclined dissolving surface. The dynamics of dissolving\nsolids demonstrated here applies equally well to solids undergoing phase\nchange, and may enhance the drift of melting icebergs, besides unraveling a\nprimal strategy by which to achieve locomotion in active matter."
    },
    {
        "anchor": "Gravitaxis of asymmetric self-propelled colloidal particles: Many motile microorganisms adjust their swimming motion relative to the\ngravitational field and thus counteract sedimentation to the ground. This\ngravitactic behavior is often the result of an inhomogeneous mass distribution\nwhich aligns the microorganism similar to a buoy. However, it has been\nsuggested that gravitaxis can also result from a geometric fore-rear asymmetry,\ntypical for many self-propelling organisms. Despite several attempts, no\nconclusive evidence for such an asymmetry-induced gravitactic motion exists.\nHere, we study the motion of asymmetric self-propelled colloidal particles\nwhich have a homogeneous mass density and a well-defined shape. In experiments\nand by theoretical modeling we demonstrate that a shape anisotropy alone is\nsufficient to induce gravitactic motion with either preferential upward or\ndownward swimming. In addition, also trochoid-like trajectories transversal to\nthe direction of gravity are observed.",
        "positive": "Understanding Collective Dynamics of Soft Active Colloids by Binary\n  Scattering: Collective motion in actively propelled particle systems is triggered on the\nvery local scale by nucleation of coherently moving units consisting of just a\nhandful of particles. These units grow and merge over time, ending up in a\nlong-range ordered, coherently-moving state. So far, there exists no bottom-up\nunderstanding of how the microscopic dynamics and interactions between the\nconstituents are related to the system's ordering instability. In this paper,\nwe study a class of models for propelled colloids allowing an explicit\ntreatment of the microscopic details of the collision process. Specifically,\nthe model equations are Newtonian equations of motion with separate force terms\nfor particles' driving, dissipation and interaction forces. Focusing on dilute\nparticle systems, we analyze the binary scattering behavior for these models,\nand determine-based on the microscopic dynamics-the corresponding\ncollision-rule, i.e., the mapping of pre-collisional velocities and impact\nparameter on post-collisional velocities. By studying binary scattering we also\nfind that the considered models for active colloids share the same principle\nfor parallel alignment: the first incoming particle (with respect to the center\nof collision) is aligned to the second particle as a result of the encounter.\nThis behavior is distinctively different to alignment in non-driven dissipative\ngases. Moreover, the obtained collision rule lends itself as a starting point\nto apply kinetic theory for propelled particle systems in order to determine\nthe phase boundary to a long-range ordered, coherently-moving state. The\nmicroscopic origin of the collision rule offers the opportunity to\nquantitatively scrutinize the predictions of kinetic theory for propelled\nparticle systems through direct comparison with multi-particle simulations."
    },
    {
        "anchor": "Spectroscopic Signatures of the Dynamical Hydrophobic Solvation Shell\n  Formation: When a hydrophilic solute in water is suddenly turned into a hydrophobic\nspecies, for instance, by photoionization, a layer of hydrated water molecules\nforms around the solute on a time scale of a few picoseconds. We study the\ndynamic build-up of the hydration shell around a hydrophobic solute on the\nbasis of a time-dependent dielectric continuum model. Information about the\nsolvent is spectroscopically extracted from the relaxation dynamics of a test\ndipole inside a static Onsager sphere in the nonequilibrium solvent. The growth\nprocess is described phenomenologically within two approaches. First, we\nconsider a time-dependent thickness of the hydration layer which grows from\nzero to a finite value over a finite time. Second, we assume a time-dependent\ncomplex permittivity within a finite layer region around the Onsager sphere.\nThe layer is modeled as a continuous dielectric with a much slower fluctuation\ndynamics. We find a time-dependent frequency shift down to the blue of the\nresonant absorption of the dipole, together with a dynamically decreasing line\nwidth, as compared to bulk water. The blue shift reflects the work performed\nagainst the hydrogen bonded network of the bulk solvent and is a directly\nmeasurable quantity. Our results are in agreement with an experiment on the\nhydrophobic solvation of iodine in water.",
        "positive": "Binding of anisotropic curvature-inducing proteins onto membrane tubes: Bin/Amphiphysin/Rvs superfamily proteins and other curvature-inducing\nproteins have anisotropic shapes and anisotropically bend biomembrane. Here, we\nreport how the anisotropic proteins bind the membrane tube and are\norientationally ordered using mean-field theory including an\norientation-dependent excluded volume. The proteins exhibit a second-order or\nfirst-order nematic transition with increasing protein density depending on the\nradius of the membrane tube. The tube curvatures for the maximum protein\nbinding and orientational order are different and varied by the protein density\nand rigidity. As the external force along the tube axis increases, a\nfirst-order transition from a large tube radius with low protein density to a\nsmall radius with high density occurs once, and subsequently, the protein\norientation tilts to the tube-axis direction. When an isotropic bending energy\nis used for the proteins with an elliptic shape, the force-dependence curves\nbecome symmetric and the first-order transition occurs twice. This theory\nquantitatively reproduces the results of meshless membrane simulation for short\nproteins, whereas deviations are seen for long proteins owing to the formation\nof protein clusters."
    },
    {
        "anchor": "Phase Separation, Edge Currents, and Hall Effect for Active Matter with\n  Magnus Dynamics: We examine run and tumble disks in two-dimensional systems where the\nparticles also have a Magnus component to their dynamics. For increased\nactivity, we find that the system forms a motility-induced phase-separated\n(MIPS) state with chiral edge flow around the clusters, where the direction of\nthe current is correlated with the sign of the Magnus term. The stability of\nthe MIPS state is non-monotonic as a function of increasing Magnus term\namplitude, with the MIPS region first extending down to lower activities\nfollowed by a break up of MIPS at large Magnus amplitudes into a gel-like\nstate. We examine the dynamics in the presence of quenched disorder and a\nuniform drive, and find that the bulk flow exhibits a drive-dependent Hall\nangle. This is a result of the side jump effect produced by scattering from the\npinning sites, and is similar to the behavior found for skyrmions in chiral\nmagnets with quenched disorder.",
        "positive": "Chiral fluid membranes with orientational order and multiple edges: We carry out Monte Carlo simulations on fluid membranes with orientational\norder and multiple edges in the presence and absence of external forces. The\nmembrane resists bending and has an edge tension, the orientational order\ncouples with the membrane surface normal through a cost for tilting, and there\nis a chiral liquid crystalline interaction. In the absence of external forces,\na membrane initialized as a vesicle will form a disk at low chirality, with the\ndirectors forming a smectic-A phase with alignment perpendicular to the\nmembrane surface except near the edge. At large chirality a catenoid-like shape\nor a trinoid-like shape is formed, depending on the number of edges in the\ninitial vesicle. This shape change is accompanied by cholesteric ordering of\nthe directors and multiple $\\pi$ walls connecting the membrane edges and\nwrapping around the membrane neck. If the membrane is initialized instead in a\ncylindrical shape and stretched by an external force, it maintains a nearly\ncylindrical shape but additional liquid crystalline phases appear. For large\ntilt coupling and low chirality, a smectic-A phase forms. For lower values of\nthe tilt coupling, a nematic phase appears at zero chirality with the average\ndirector oriented perpendicular to the long axis of the membrane, while for\nnonzero chirality a cholesteric phase appears. The $\\pi$ walls are tilt walls\nat low chirality and transition to twist walls as chirality is increased. We\nconstruct a continuum model of the director field to explain this behavior."
    },
    {
        "anchor": "Polymer chains in confined spaces and flow-injection problems: some\n  remarks: We revisit the classical problem of the behavior of an isolated linear\npolymer chain in confined spaces, introducing the distinction between two\ndifferent confinement regimes (the {\\it weak} and the {\\it strong} confinement\nregimes, respectively). We then discuss some recent experimental findings\nconcerning the partitioning of individual polymers into protein pores. We also\ngeneralize our study to the case of branched polymers, and study the\nflow-injection properties of such objects into nanoscopic pores, for which the\nstrong confinement regime plays an important role.",
        "positive": "Role of microgel stiffness in particle self-assembly and suspension\n  rheology across the lower consolute solution temperature: We synthesize thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) colloidal\nmicrogel particles of different stiffnesses by controlling the concentration of\ncrosslinker in a one-pot synthesis method. We employ oscillatory rheology and\ncryogenic scanning electron microscopy to study the temperature and\nstiffness-induced mechanical properties and microscopic structures of dense\naqueous suspensions of the synthesized PNIPAM microgels. Using Fourier\ntransform infrared (FTIR) spectroscopy, we show that particle hydrophobicity\nincreases with increasing suspension temperature and decreasing particle\nstiffness. Our zeta potential measurements of soft PNIPAM particles and those\nof intermediate stiffnesses demonstrate that these particles are\nelectrostatically unstable and prone to aggregation even at temperatures below\nthe lower consolute solution temperature (LCST). In contrast, stiff PNIPAM\nparticles in dilute aqueous suspensions are electrostatically stabilized at all\ntemperatures explored in this study. Interestingly, our frequency and strain\namplitude sweep rheology experiments reveal that the linear viscoelastic moduli\nand yield stresses of all the PNIPAM suspensions increase when the temperature\nis raised above the LCST. Combining cryogenic scanning electron microscopy\n(cryo-SEM) and rheology, we demonstrate that dense suspensions of soft PNIPAM\nmicrogels show a gel-liquid-gel transition with increase in temperature across\nthe LCST. Suspensions of stiff particles, in contrast, exhibit a glass-glass\ntransition under the same temperature sweep conditions and do not pass through\nan intermediate liquid state."
    },
    {
        "anchor": "Freezing of Spinodal Decompostion by Irreversible Chemical Growth\n  Reaction: We present a description of the freezing of spinodal decomposition in\nsystems, which contain simultaneous irreversible chemical reactions, in the\nhydrodynamic limit approximation. From own results we conclude, that the\nchemical reaction leads to an onset of spinodal decomposition also in the case\nof an initial system which is completely miscible and can lead to an extreme\nretardation of the dynamics of the spinodal decomposition, with the probability\nof a general freezing of this process, which can be experimetally observed in\nsimultaneous IPN formation.",
        "positive": "Mode coupling theory for molecular liquids: What can we learn from a\n  system of hard ellipsoids?: Molecular fluids show rich and complicated dynamics close to the glass\ntransition. Some of these observations are related to the fact that\ntranslational and orientational degrees of freedom couple in nontrivial ways. A\nmodel system which can serve as a paradigm to understand these couplings is a\nsystem of hard ellipsoids of revolution. To test this we compare at the ideal\nglass transition the static molecular correlators of a linear A-B Lennard-Jones\nmolecule obtained from a molecular dynamics simulation with a selected fluid of\nhard ellipsoids for which the static correlators have been obtained using\nPercus-Yevick theory. We also demonstrate that the critical non-ergodicity\nparameters obtained from molecular mode coupling theory for both systems show a\nremarkable similarity at the glass transition, provided the aspect ratio is\nchosen properly. Therefore we conclude that a system of hard ellipsoids can\nindeed be used to understand part of the essential behaviour of such a simple\nmolecular system like the A-B Lennard-Jones molecules in the vicinity of the\nideal glass transition."
    },
    {
        "anchor": "How many ways a cell can move: the modes of self-propulsion of an active\n  drop: Numerous physical models have been proposed to explain how cell motility\nemerges from internal activity, mostly focused on how crawling motion arises\nfrom internal processes. Here we offer a classification of self-propulsion\nmechanisms based on general physical principles, showing that crawling is not\nthe only way for cells to move on a substrate. We consider a thin drop of\nactive matter on a planar substrate and fully characterize its autonomous\nmotion for all three possible sources of driving: (i) the stresses induced in\nthe bulk by active components, which allow in particular tractionless motion,\n(ii) the self-propulsion of active components at the substrate, which gives\nrise to crawling motion, and (iii) a net capillary force, possibly\nself-generated, and coupled to internal activity. We determine travelling-wave\nsolutions to the lubrication equations as a function of a dimensionless\nactivity parameter for each mode of motion. Numerical simulations are used to\ncharacterize the drop motion over a wide range of activity magnitudes, and\nexplicit analytical solutions in excellent agreement with the simulations are\nderived in the weak-activity regime.",
        "positive": "Viscoelastic contact mechanics between randomly rough surfaces: We present exact numerical results for the friction force and the contact\narea for a viscoelastic solid (rubber) in sliding contact with hard, randomly\nrough substrates. The rough surfaces are self-affine fractal with roughness\nover several decades in length scales. We calculate the contribution to the\nfriction from the pulsating deformations induced by the substrate asperities.\nWe also calculate how the area of real contact, $A(v,p) $, depends on the\nsliding speed $v$ and on the nominal contact pressure $p$, and we show how the\ncontact area for any sliding speed can be obtained from a universal master\ncurve $A(p)$. The numerical results are found to be in good agreement with the\npredictions of an analytical contact mechanics theory."
    },
    {
        "anchor": "On the chain length dependence of local correlations in polymer melts\n  and a perturbation theory of symmetric polymer blends: The self-consistent field (SCF) theory of dense polymer liquids assumes that\nshort-range correlations are almost independent of how monomers are connected\ninto polymers. Some limits of this idea are explored in the context of a\nperturbation theory for mixtures of structurally identical polymer species, A\nand B, in which the AB pair interaction differs slightly from the AA and BB\ninteraction, and the difference is controlled by a parameter alpha Expanding\nthe free energy to O(\\alpha) yields an excess free energy of the form alpha\n$z(N)\\phi_{A}\\phi_{B}$, in both lattice and continuum models, where z(N) is a\nmeasure of the number of inter-molecular near neighbors of each monomer in a\none-component liquid. This quantity decreases slightly with increasing N\nbecause the self-concentration of monomers from the same chain is slightly\nhigher for longer chains, creating a deeper correlation hole for longer chains.\nWe analyze the resulting $N$-dependence, and predict that $z(N) = z^{\\infty}[1\n+ \\beta \\bar{N}^{-1/2}]$, where $\\bar{N}$ is an invariant degree of\npolymerization, and $\\beta=(6/\\pi)^{3/2}$. This and other predictions are\nconfirmed by comparison to simulations. We also propose a way to estimate the\neffective interaction parameter appropriate for comparisons of simulation data\nto SCF theory and to coarse-grained theories of corrections to SCF theory,\nwhich is based on an extrapolation of coefficients in this perturbation theory\nto the limit $N \\to \\infty$. We show that a renormalized one-loop theory\ncontains a quantitatively correct description of the $N$-dependence of local\nstructure studied here.",
        "positive": "Maximizing Entropy by Minimizing Area: Towards a New Principle of\n  Self-Organization: We propose a heuristic explanation for the numerous non-close-packed crystal\nstructures observed in various colloidal systems. By developing an analogy\nbetween soap froths and the soft coronas of fuzzy colloids, we provide a\ngeometrical interpretation of the free energy of soft spheres. Within this\npicture, we show that the close-packing rule associated with hard-core\ninteraction and positional entropy of particles is frustrated by a minimum-area\nprinciple associated with the soft tail and internal entropy of the soft\ncoronas. We also discuss these ideas in terms of crystal architecture and pair\ndistribution functions and analyze the phase diagram of a model\nhard-sphere--square-shoulder system within the cellular theory. We find that\nthe A15 lattice, known to be area minimizing, is favored for a reasonable range\nof model parameters and so it is among the possible equilibrium states for a\nvariety of colloidal systems. We also show that in the case of short-range\nconvex potentials the A15 and other non-close-packed lattices coexist over a\nbroad ranges of densities, which could make their identification difficult."
    },
    {
        "anchor": "Hydrodynamic correlations of viscoelastic fluids by multiparticle\n  collision dynamics simulations: The emergent fluctuating hydrodynamics of a viscoelastic fluid modeled by the\nmultiparticle collision dynamics (MPC) approach is studied. The fluid is\ncomposed of flexible, Gaussian phantom polymers, which interact by local\nmomentum-conserving stochastic MPC collisions. For comparison, the analytical\nsolution of the linearized Navier-Stokes equation is calculated, where\nviscoelasticity is taken into account by a time-dependent shear relaxation\nmodulus. The fluid properties are characterized by the transverse velocity\nautocorrelation function in Fourier space as well as in real space. Various\npolymer lengths are considered---from dumbbells to (near-)continuous polymers.\nViscoelasticity affects the fluid properties and leads to strong correlations,\nwhich overall decay exponentially in Fourier space. In real space, the\ncenter-of-mass velocity autocorrelation function of individual polymers\nexhibits a long-time tail independent of polymer length, which decays as\n$t^{-3/2}$, similar to a Newtonian fluid, in the asymptotic limit $t \\to\n\\infty$. Moreover, for long polymers an additional power-law decay appears at\ntime scales shorter than the longest polymer relaxation time with the same time\ndependence, but negative correlations, and the polymer length dependence\n$L^{-1/2}$. Good agreement is found between the analytical and simulation\nresults.",
        "positive": "Frictional weakening induced by cohesion: the numerical case of cohesive\n  granular failures: The failure of 2D numerical cohesive granular steps collapsing under gravity\nare simulated for a large range of cohesion. Focussing on the cumulative\ndisplacement of the grains, and defining a displacement threshold, we establish\na sensible criterion for capturing the failure characteristics. We are able to\nlocate the failure in time and to identify the different stages of the\ndestabilisation. We find that the onset of the failure is delayed by increasing\ncohesion, but its duration becomes shorter. Defining a narrow displacement\ninterval, a well-defined shear band revealing the failure comes out. Solving\nthe equilibrium of the failing block, we are able to make successful\npredictions for the dependance between failure angle and cohesion, thereby\ndisclosing two distinct frictional behaviour: while friction remains constant\nat small cohesion, it significantly decreases with cohesive properties at\nlarger cohesion. The results hence reveal two regimes for the behaviour of\ncohesive granular matter depending on cohesion strength, revealing a\ncohesion-induced weakening mechanism."
    },
    {
        "anchor": "A charged finitely extensible dumbbell model: Explaining rheology of\n  dilute polyelectrolyte solutions: A robust non-Newtonian fluid model of dilute polyelectrolyte solutions is\nderived from kinetic theory arguments. Polyelectrolyte molecules are modeled as\nfinitely elongated nonlinear elastic dumbbells, where effective charges\n(interacting through a simple Coulomb force) are added to the beads in order to\nmodel the repulsion between the charged sections of polyelectrolyte chains. It\nis shown that the relative strength of this repulsion is regulated by the\nelectric-to-elastic energy ratio, $E$, which is one of the key parameters of\nthe model. In particular, $E$ accounts for the intrinsic rigidity of\npolyelectrolyte molecules and can be used to explain the impact of solvent\nsalinity on polyelectrolyte rheology. With two preaveraging approximations, the\nconstitutive equations of the resulting fluid model are formulated in closed\nform. Material functions predicted by the model for steady shear flow, steady\nextensional flow, small-amplitude oscillatory shear flow, and start-up and\ncessation of steady shear flow are obtained and investigated using a\ncombination of analytical and numerical methods. In particular, it is shown how\nthese material functions depend on $E$. The two limiting cases of the model --\nuncharged dumbbells ($E=0$) and rigid dumbbells ($E\\to \\infty$) -- are included\nin the analysis. It is found that despite its simplicity, the model predicts\nmost of experimentally observed rheological features of polyelectrolyte\nsolutions.",
        "positive": "Fluctuations in Chemical Gelation: We study a chemical gelation model in two dimensions which includes both\nmonomer aggregations and bond fluctuations. Our numerical simulation shows that\na sol-gel transition occurs when an initial monomer concentration is above a\ncritical concentration. Fractal aggregates grow until the sol-gel transition\noccurs. After the gelation, however, bond fluctuations break the fractal\nstructure and a novel inhomogeneous gel fibre network appears instead. A pore\nsize distribution of the inhomogeneous structure shows the existence of\nhierarchical structures in the gel phase. It is also found that slow dynamics\nappear near the critical concentration."
    },
    {
        "anchor": "Influence of lattice disorder on the structure of persistent polymer\n  chains: We study the static properties of a semiflexible polymer exposed to a\nquenched random environment by means of computer simulations. The polymer is\nmodeled as two-dimensional Heisenberg chain. For the random environment we\nconsider hard disks arranged on a square lattice. We apply an off-lattice\ngrowth algorithm as well as the multicanonical Monte Carlo method to\ninvestigate the influence of both disorder occupation probability and polymer\nstiffness on the equilibrium properties of the polymer. We show that the\nadditional length scale induced by the stiffness of the polymer extends the\nwell-known phenomenology considerably. The polymer's response to the disorder\nis either contraction or extension depending on the ratio of polymer stiffness\nand void space extension. Additionally, the periodic structure of the lattice\nis reflected in the observables that characterize the polymer.",
        "positive": "Interaction of Acoustic and Quasi-Elastic Modes in Liquid Water on\n  Nanometer Length Scales: We investigate the presence of an acoustic-quasi-elastic interaction\ncontribution in the IXS spectra of liquid water at 301K using inelastic x-ray\nscattering with sub-meV energy resolution at momentum transfers 0.77<=Q<=4.20\n/nm. The contribution appears due to the overlap the acoustic mode with the\ntail the quasi-elastic mode and is fully consistent with hydrodynamic theory.\nIncorporating this interaction allows us to describe the dynamic structure\nfactor, S(Q,w), without introducing an extra mode, and may help explain earlier\ncontradictory interpretations. The sound velocity, and relative intensity of\nthe quasi-elastic and acoustic mode, plateau for Q>2/nm at values consistent\nwith a viscoelastic generalization of the Landau-Placzek relation."
    },
    {
        "anchor": "Structure and relaxation processes of an anisotropic molecular fluid\n  confined into 1D nanochannels: Structural order parameters of a smectic liquid crystal confined into the\ncolumnar form of porous silicon are studied using neutron scattering and\noptical spectroscopic techniques. It is shown that both the translational and\norientational anisotropic properties of the confined phase strongly couple to\nthe one-dimensional character of the porous silicon matrix. The influence of\nthis confinement induced anisotropic local structure on the molecular\nreorientations occuring in the picosecond timescale is discussed.",
        "positive": "Self-assembly of bi-functional patchy particles with anisotropic shape\n  into polymers chains: theory and simulations: Concentrated solutions of short blunt-ended DNA duplexes, down to 6 base\npairs, are known to order into the nematic liquid crystal phase. This\nself-assembly is due to the stacking interactions between the duplex terminals\nthat promotes their aggregation into poly-disperse chains with a significant\npersistence length. Experiments show that liquid crystals phases form above a\ncritical volume fraction depending on the duplex length. We introduce and\ninvestigate via numerical simulations, a coarse-grained model of DNA\ndouble-helical duplexes. Each duplex is represented as an hard quasi-cylinder\nwhose bases are decorated with two identical reactive sites. The stacking\ninteraction between terminal sites is modeled via a short-range square-well\npotential. We compare the numerical results with predictions based on a free\nenergy functional and find satisfactory quantitative matching of the\nisotropic-nematic phase boundary and of the system structure. Comparison of\nnumerical and theoretical results with experimental findings confirm that the\nDNA duplexes self-assembly can be properly modeled via equilibrium\npolymerization of cylindrical particles and enables us to estimate the stacking\nenergy."
    },
    {
        "anchor": "Insights into the interactions among Surfactin, betaines, and PAM:\n  surface tension, small-angle neutron scattering, and small-angle X-ray\n  scattering study: The interactions among neutral polymer polyacrylamide (PAM) and the\nbiosurfactant Surfactin and four betaines,\nN-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SDDAB),\nN-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (STDAB),\nN-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SHDAB), and\nN-dodecyl-N,N-dimethyl-2-ammonio-acetate (C12BE), in phosphate buffer solution\n(PBS) have been studied by surface tension measurements, small-angle neutron\nscattering (SANS), small-angle X-ray scattering (SAXS), and rheological\nexperiments. It has been confirmed that the length of alkyl chain is a key\nparameter of interaction between betaines and PAM. Differences in scattering\ncontrast between X-ray and neutrons for surfactants and PAM molecules provide\nthe opportunity to separately follow the changes of structure of PAM and\nsurfactant aggregates. At concentrations of betaines higher than CMC (critical\nmicelle concentration) and C2 (CMC of surfactant with the presence of polymer),\nspherical micelles are formed in betaines and betaines/PAM solutions.\nTransition from spherical to rod-like aggregates (micelles) has been observed\nin solutions of Surfactin and Surfactin/SDDAB ({\\alpha}Surfactin = 0.67 (molar\nfraction)) with addition of 0.8 wt % of PAM. The conformation change of PAM\nmolecules only can be observed for Surfactin/SDDAB/PAM system. Viscosity values\nfollow the structural changes suggested from scattering measurements i.e.,\ngradually increases for mixtures PAM -> Surfactin/PAM -> Surfactin/SDDAB/PAM in\nPBS.",
        "positive": "Surface Excitations in a Bose-Einstein Condensate: Surface modes in a Bose-Einstein condensate of sodium atoms have been\nstudied. We observed excitations of standing and rotating quadrupolar and\noctopolar modes. The modes were excited with high spatial and temporal\nresolution using the optical dipole force of a rapidly scanning laser beam.\nThis novel technique is very flexible and should be useful for the study of\nrotating Bose-Einstein condensates and vortices."
    },
    {
        "anchor": "Shape and size changes of adherent elastic epithelia: Epithelial tissues play a fundamental role in various morphogenetic events\nduring development and early embryogenesis. Although epithelial monolayers are\noften modeled as two-dimensional (2D) elastic surfaces, they distinguish\nthemselves from conventional thin elastic plates in three important ways - the\npresence of an apical-basal polarity, spatial variability of cellular\nthickness, and their nonequilibrium active nature. Here, we develop a minimal\ncontinuum model of a planar epithelial tissue as an active elastic material\nthat incorporates all these features. We start from a full three-dimensional\n(3D)description of the tissue and derive an effective 2D model that captures,\nthrough the curvature of the apical surface, both the apical-basal asymmetry\nand the spatial geometry of the tissue. Crucially, variations of active\nstresses across the apical-basal axis lead to active torques that can drive\ncurvature transitions. By identifying four distinct sources of activity, we\nfind that bulk active stresses arising from actomyosin contractility and growth\ncompete with boundary active tensions due to localized actomyosin cables and\nlamellipodial activity to generate the various states spanning the morphospace\nof a planar epithelium. Our treatment hence unifies 3D shape deformations\nthrough the coupled mechanics of apical curvature change and in-plane\nexpansion/contraction of substrate-adhered tissues. Finally, we discuss the\nimplications of our results for some biologically relevant processes such as\ntissue folding at the onset of lumen formation.",
        "positive": "Directing liquid crystalline self-organization of rod-like particles\n  through tunable attractive single tips: Dispersions of rodlike colloidal particles exhibit a plethora of liquid\ncrystalline states, including nematic, smectic A, smectic B, and columnar\nphases. This phase behavior can be explained by presuming the predominance of\nhard-core volume exclusion between the particles. We show here how the\nself-organization of rodlike colloids can be controlled by introducing a weak\nand highly localized directional attractive interaction between one of the ends\nof the particles. This has been performed by functionalizing the tips of\nfilamentous viruses by means of regioselectively grafting fluorescent dyes onto\nthem, resulting in a hydrophobic patch whose attraction can be tuned by varying\nthe number of bound dye molecules. We show, in agreement with our computer\nsimulations, that increasing the single tip attraction stabilizes the smectic\nphase at the expense of the nematic phase, leaving all other liquid crystalline\nphases invariant. For a sufficiently strong tip attraction, the nematic state\nmay be suppressed completely to get a direct isotropic liquid-to-smectic phase\ntransition. Our findings provide insights into the rational design of building\nblocks for functional structures formed at low densities."
    },
    {
        "anchor": "Colloidal ionic complexes on periodic substrates: ground state\n  configurations and pattern switching: We theoretically and numerically studied ordering of \"colloidal ionic\nclusters\" on periodic substrate potentials as those generated by optical\ntrapping. Each cluster consists of three charged spherical colloids: two\nnegatively and one positively charged. The substrate is a square or rectangular\narray of traps, each confining one such cluster. By varying the lattice\nconstant from large to small, the observed clusters are first rod-like and form\nferro- and antiferro-like phases, then they bend into a banana-like shape and\nfinally condense into a percolated structure. Remarkably, in a broad parameter\nrange between single-cluster and percolated structures, we have found stable\nsupercomplexes composed of six colloids forming grape-like or rocket-like\nstructures. We investigated the possibility of macroscopic pattern switching by\napplying external electrical fields.",
        "positive": "Understanding Creep in Vitrimers: Insights from Molecular Dynamics\n  Simulations: Vitrimers offer a promising sustainable alternative to conventional epoxies\ndue to their recyclability. Vitrimers are covalent adaptive networks where some\nbonds can break and reform above the vitrimer transition temperature. While\nthis can lead to desirable behavior such as malleability, this also leads to\nundesirable rheological behavior such as low-temperature creep. In this work,\nwe investigate the molecular mechanisms of the creep of vitrimers using\nmolecular dynamics simulations. The interplay between dynamic bonding with\nmechanical loading is modeled using a topology-based reaction scheme. The creep\nbehavior is compared against cross-linked epoxies with dynamic reactions to\nunderstand the unique aspects related to dynamic bonding. It is found that the\nfree volume that arises from tensile loads is reduced in vitrimers through\ndynamic bond rearrangement. An important feature that explains the difference\nin secondary creep behavior between conventional epoxies and vitrimers is the\norientation of the dynamic bonds during loading. In vitrimers, the dynamic\nbonds preferentially align orthogonal to the loading axis, decreasing the axial\nstiffness during secondary creep, resulting in larger creep strain compared to\nepoxies. Over longer timescales, such increased strain leads to void growth,\nresulting in tertiary creep. Thus, chemistry changes or additives that can\nprevent the initial realignment of dynamic bonds, and therefore subsequent void\ngrowth, can be an effective strategy to mitigate creep in vitrimers."
    },
    {
        "anchor": "Cooperative intramolecular dynamics control the chain-length-dependent\n  glass transition in polymers: The glass transition is a long-standing unsolved problem in materials\nscience. For polymers, our understanding of glass-formation is particularly\npoor due to the added complexity of chain connectivity and flexibility;\nstructural relaxation of polymers thus involves a complex interplay between\nintra- and inter-molecular cooperativity. Here we study how the glass\ntransition temperature Tg varies with molecular weight M for different polymer\nchemistries and chain flexibilities. We find that Tg(M) is controlled by the\naverage mass (or volume) per conformational degree of freedom, and that a\n`local' molecular relaxation (involving a few conformers) controls the\nlarger-scale cooperative alpha relaxation responsible for Tg. We propose that\ndynamic facilitation where a `local' relaxation facilitates adjacent\nrelaxations, leading to hierarchical dynamics, can explain our observations\nincluding logarithmic Tg(M) dependences. Our study provides a new understanding\nof molecular relaxations and the glass transition in polymers, which paves the\nway for predictive design of polymers based on monomer-scale metrics.",
        "positive": "Measurement theory of a density profile of colloid particles on a flat\n  surface: Conversion of force acting on a colloidal probe into pressure on its\n  surface element: Recently, we proposed a method that converts the force between two-large\ncolloids into the pressure on the surface element (FPSE conversion) in a system\nof a colloidal solution. Using it, the density distribution of the small\ncolloids around the large colloid is calculated. In a similar manner, in this\nletter, we propose a transform theory for colloidal probe atomic force\nmicroscopy (colloidal probe AFM), which transforms the force acting on the\ncolloidal probe into the density distribution of the small colloids on a flat\nsurface. If measured condition is proper one, in our view, it is possible for\nthe transform theory to be applied for liquid AFM and obtain the liquid\nstructure. The transform theory we derived is briefly explained in this letter."
    },
    {
        "anchor": "Dispersion relation of lipid membrane shape fluctuations by neutron\n  spin-echo spectrometry: We have studied the mesoscopic shape fluctuations in aligned multilamellar\nstacks of DMPC bilayers using the neutron spin-echo technique. The\ncorresponding in plane dispersion relation $\\tau^{-1}$(q$_{||}$) at different\ntemperatures in the gel (ripple, P$_{\\beta'}$) and the fluid (L$_{\\alpha}$)\nphase of this model system has been determined. Two relaxation processes, one\nat about 10ns and a second, slower process at about 100ns can be quantified.\nThe dispersion relation in the fluid phase is fitted to a smectic hydrodynamic\ntheory, with a correction for finite q$_z$ resolution. We extract values for,\nthe bilayer bending rigidity $\\kappa$, the compressional modulus of the stacks\n$B$, and the effective sliding viscosity $\\eta_3$. The softening of a mode\nwhich can be associated with the formation of the ripple structure is observed\nclose to the main phase transition.",
        "positive": "Elemental substitution tuned magneto elastoviscous behavior of nanoscale\n  ferrite MFe2O4 M = Mn, Fe, Co, Ni based complex fluids: The present article reports the governing influence of substituting the M2\nsite in nanoscale MFe2O4 spinel ferrites by different magnetic metals\nFe,Mn,Co,Ni on magnetorheological and magneto elastoviscous behaviors of the\ncorresponding magnetorheological fluids MRFs. Different doped MFe2O4\nnanoparticles have been synthesized using the polyol assisted hydrothermal\nmethod. Detailed steady and oscillatory shear rheology have been performed on\nthe MRFs to determine the magneto-viscoelastic responses. The MRFs exhibit\nshear thinning behavior and augmented yield characteristics under influence of\nmagnetic field. The steady state magnetoviscous behaviors are scaled against\nthe governing Mason number and self similar response from all the MRFs have\nbeen noted. The MRFs conform to an extended Bingham plastic model under field\neffect. Transient magnetoviscous responses show distinct hysteresis behaviors\nwhen the MRFs are exposed to time varying magnetic fields. Oscillatory shear\nstudies using frequency and strain amplitude sweeps exhibit predominant solid\nlike behaviors under field environment. However, the relaxation behaviors and\nstrain amplitude sweep tests of the MRFs reveal that while the fluids show\nsolid like behaviors under field effect, they cannot be termed as typical\nelastic fluids. Comparisons show that the MnFe2O4 MRFs have superior yield\nperformance among all. However, in case of dynamic and oscillatory systems,\nCoFe2O4 MRFs show the best performance. The viscoelastic responses of the MRFs\nare noted to correspond to a three element viscoelastic model. The study may\nfind importance in design and development strategies of nano MRFs for different\napplications."
    },
    {
        "anchor": "Statistical field theory for nonlinear elasticity of polymer networks\n  with excluded volume interactions: Polymer networks formed by cross linking flexible polymer chains are\nubiquitous in many natural and synthetic soft-matter systems. Current\nmicromechanics models generally do not account for excluded volume interactions\nexcept, for instance, through imposing a phenomenological incompressibility\nconstraint at the continuum scale. This work aims to examine the role of\nexcluded volume interactions on the mechanical response. The approach is based\non the framework of the self-consistent statistical field theory of polymers,\nwhich provides an efficient mesoscale approach that enables the accounting of\nexcluded volume effects without the expense of large-scale molecular modeling.\nA mesoscale representative volume element is populated with multiple\ninteracting chains, and the macroscale nonlinear elastic deformation is imposed\nby mapping the end-to-end vectors of the chains by this deformation. In the\nabsence of excluded volume interactions, it recovers the closed-form results of\nthe classical theory of rubber elasticity. With excluded volume interactions,\nthe model is solved numerically in three dimensions using a finite element\nmethod to obtain the energy, stresses, and linearized moduli under imposed\nmacroscale deformation. Highlights of the numerical study include: (i) the\nlinearized Poisson's ratio is very close to the incompressible limit without a\nphenomenological imposition of incompressibility; (ii) despite the harmonic\nGaussian chain as a starting point, there is an emergent strain-softening and\nstrain-stiffening response that is characteristic of real polymer networks,\ndriven by the interplay between the entropy and the excluded volume\ninteractions; and (iii) the emergence of a deformation-sensitive localization\ninstability at large excluded volumes.",
        "positive": "Non-equilibrium interfaces in colloidal fluids: The time-dependent structure, interfacial tension, and evaporation of an\noversaturated colloid-rich (liquid) phase in contact with an undersaturated\ncolloid-poor (vapor) phase of a colloidal dispersion is investigated\ntheoretically during the early-stage relaxation, where the interface is\nrelaxing towards a local equilibrium state while the bulk phases are still out\nof equilibrium. Since systems of this type exhibit a clear separation of\ncolloidal and solvent relaxation time scales with typical times of interfacial\ntension measurements in between, they can be expected to be suitable for\nanalogous experimental studies, too. The major finding is that, irrespective of\nhow much the bulk phases differ from two-phase coexistence, the interfacial\nstructure and the interfacial tension approach those at two-phase coexistence\nduring the early-stage relaxation process. This is a surprising observation\nsince it implies that the relaxation towards global equilibrium of the\ninterface is not following but preceding that of the bulk phases. Scaling forms\nfor the local chemical potential, the flux, and the dissipation rate exhibit\nqualitatively different leading order contributions depending on whether an\nequilibrium or a non-equilibrium system is considered. The degree of\nnon-equilibrium between the bulk phases is found to not influence the\nqualitative relaxation behavior (i.e., the values of power-law exponents), but\nto determine the quantitative deviation of the observed quantities from their\nvalues at two-phase coexistence. Whereas the underlying dynamics differs\nbetween colloidal and molecular fluids, the behavior of quantities such as the\ninterfacial tension approaching the equilibrium values during the early-stage\nrelaxation process, during which non-equilibrium conditions of the bulk phases\nare not changed, can be expected to occur for both types of systems."
    },
    {
        "anchor": "Extended space charge near non-ideally selective membranes and\n  nanochannels: We demonstrate the role of selectivity variation in the structure of the\nnon-equilibrium extended space-charge using 1D analytic and 2D numerical\nPoisson-Nernst-Planck models for the electro- diffusive transport of a\nsymmetric electrolyte. This provides a deeper understanding of the underly- ing\nmechanism behind a previously-observed maximum in the resistance-voltage curve\nfor a shallow micro-nanochannel interface device [Schiffbauer, Liel, Leibowitz,\nPark, and Yossifon, submitted to Phys. Rev. E.]. The current study helps to\nestablish a connection between parameters such as the geometry and nanochannel\nsurface-charge and the control of selectivity and resistance in the\nover-limiting current regime.",
        "positive": "Influence of Cohesive Energy and Chain Stiffness on Polymer Glass\n  Formation: The generalized entropy theory is applied to assess the joint influence of\nthe microscopic cohesive energy and chain stiffness on glass formation in\npolymer melts using a minimal model containing a single bending energy and a\nsingle (monomer averaged) nearest neighbor van der Waals energy. The analysis\nfocuses on the combined impact of the microscopic cohesive energy and chain\nstiffness on the magnitudes of the isobaric fragility parameter $m_P$ and the\nglass transition temperature $T_g$. The computations imply that polymers with\nrigid structures and weak nearest neighbor interactions are the most fragile,\nwhile $T_g$ becomes larger when the chains are stiffer and/or nearest neighbor\ninteractions are stronger. Two simple fitting formulas summarize the\ncomputations describing the dependence of $m_P$ and $T_g$ on the microscopic\ncohesive and bending energies. The consideration of the combined influence of\nthe microscopic cohesive and bending energies leads to the identification of\nsome important design concepts, such as iso-fragility and iso-$T_g$ lines,\nwhere, for instance, iso-fragility lines are contours with constant $m_P$ but\nvariable $T_g$. Several thermodynamic properties are found to remain invariant\nalong the iso-fragility lines, while no special characteristics are detected\nalong the iso-$T_g$ lines. Our analysis supports the widely held view that\nfragility provides more fundamental insight for the description of glass\nformation than $T_g$."
    },
    {
        "anchor": "Crystallization of hard spheres revisited. II. Thermodynamic modeling,\n  nucleation work, and the surface of tension: Combining three numerical methods (forward flux sampling, seeding of\ndroplets, and finite size droplets), we probe the crystallization of hard\nspheres over the full range from close to coexistence to the spinodal regime.\nWe show that all three methods allow to sample different regimes and agree\nperfectly in the ranges where they overlap. By combining the nucleation work\ncalculated from forward flux sampling of small droplets and the nucleation\ntheorem, we show how to compute the nucleation work spanning three orders of\nmagnitude. Using a variation of the nucleation theorem, we show how to extract\nthe pressure difference between the solid droplet and ambient liquid. Moreover,\ncombining the nucleation work with the pressure difference allows us to\ncalculate the interfacial tension of small droplets. Our results demonstrate\nthat employing bulk quantities yields inaccurate results for the nucleation\nrate.",
        "positive": "Two diverging length scales in the structure of jammed packings: At densities higher than the jamming transition for athermal, frictionless\nrepulsive spheres we find two distinct length scales, both of which diverge as\na power law as the transition is approached. The first, $\\xi_{Z}$, is\nassociated with the two-point correlation function for the number of contacts\non two particles as a function of the particle separation. The second,\n$\\xi_{f}$, is associated with contact-number fluctuations in subsystems of\ndifferent sizes. On scales below $\\xi_{f}$ the fluctuations are highly\nsuppressed, similar to the phenomenon of hyperuniformity usually associated\nwith density fluctuations. The exponents for the divergence of $\\xi_{Z}$ and\n$\\xi_{f}$ are different and appear to be different in two and three dimensions."
    },
    {
        "anchor": "Ab Initio Modeling Of Friction Reducing Agents Shows Quantum Mechanical\n  Interactions Can Have Macroscopic Manifestation: Two of the most commonly encountered friction reducing agents used in plastic\nsheet production are the amides known as erucamide and behenamide, which\ndespite being almost identical chemically, lead to markedly different values of\nthe friction coefficient. To understand the origin of this contrasting\nbehavior, in this work we model brushes made of these two types of linear chain\nmolecules using quantum mechanical numerical simulations under the Density\nFunctional Theory at the B97D/6-31G(d,p)level of theory. Four chains of\nerucamide and behenamide were linked to a 2X10 zigzag graphene sheet and\noptimized both in vacuum and in continuous solvent using the SMD implicit\nsolvation model. We find that erucamide chains tend to remain closer together\nthrough {\\pi}{\\pi} stacking interactions arising from the double bonds located\nat C13 C14, a feature behenamide lacks and thus a more spread configuration is\nobtained with the latter. It is argued that this arrangement of the erucamide\nchains is responsible for the lower friction coefficient of erucamide brushes,\ncompared with behenamide brushes, which is a macroscopic consequence of\ncooperative quantum mechanical interactions. While only quantum level\ninteractions are modeled here, we show that behenamide chains are more spread\nout in the brush than erucamide chains as a consequence of those interactions.\nThe spread out configuration allows more solvent particles to penetrate the\nbrush, leading in turn to more friction, in agreement with macroscopic\nmeasurements and mesoscale simulations of the friction coefficient reported in\nthe literature.",
        "positive": "Anharmonic Coupling between Intermolecular Motions of Water Revealed by\n  Terahertz Kerr Effect: Formation of local molecular structures in liquid water is believed to have\nmarked effect on the bulk properties of water, however, resolving such\nstructural motives in an experiment is challenging. This challenge might be\nhandled if the relevant low-frequency structural motion of the liquid is\ndirectly driven with an intense electromagnetic pulse. Here, we resonantly\nexcite diffusive reorientational motions in water with intense terahertz pulses\nand measure the resulting transient optical birefringence. The observed\nresponse is shown to arise from a particular configuration, namely the\nrestricted trans-lational motion of water molecules whose motions are\npredominantly orthogonal to the dipole moment of the excited neighboring water\nmolecules. Accordingly, we estimate the strength of the anharmonic coupling\nbetween the rotational and the restricted translational degrees of freedom of\nwater."
    },
    {
        "anchor": "Locomotion of magnetoelastic membranes in viscous fluids: The development of multifunctional and biocompatible microrobots for\nbiomedical applications relies on achieving locomotion through viscous fluids.\nHere, we describe a framework for swimming in homogeneous magnetoelastic\nmembranes composed of superparamagnetic particles. By solving the equations of\nmotion, we find the dynamical modes of circular membranes in precessing\nmagnetic fields, which are found to actuate in or out of synchronization with a\nmagnetic field precessing above or below a critical precession frequency,\n$\\omega_c$, respectively. For frequencies larger than $\\omega_c$, synchronized\nrotational and radial waves propagate on the membrane. These waves give rise to\nlocomotion in an incompressible fluid at low Reynolds number using the lattice\nBoltzmann approach. Non-reciprocal motion resulting in swimming is achieved by\nbreaking the morphological symmetry of the membrane, attained via truncation of\na circular segment. The membrane translation can be adapted to a predetermined\npath by programming the external magnetic field. Our results lay the foundation\nfor achieving directed motion in thin, homogeneous magnetoelastic membranes\nwith a diverse array of geometries.",
        "positive": "On twinning in smectic crystals: It is shown that mechanical twinning in smectic crystals is possible. The\nstructure of the boundary of twins for a small disorientation of crystallites\nis determined. The periodic twin structure, which should appear at the tension\nof the smectic layer, is proposed."
    },
    {
        "anchor": "Mesoscopic theory of the viscoelasticity of polymers: We have advanced our previous static theory of polymer entanglement involving\nan extended Cahn-Hilliard functional, to include time-dependent dynamics. We go\nbeyond the Gaussian approximation, to the one-loop level, to compute the\nfrequency dependent storage and loss moduli of the system. The three parameters\nin our theory are obtained by fitting to available experimental data on\npolystyrene melts of various chain lengths. This provides a physical\nrepresentation of the parameters in terms of the chain length of the system. We\ndiscuss the importance of the various terms in our energy functional with\nrespect to their contribution to the viscoelastic response of the polymeric\nsystem.",
        "positive": "Mesoscopic simulation study of wall roughness effects in micro-channel\n  flows of dense emulsions: We study the Poiseuille flow of a soft-glassy material above the jamming\npoint, where the material flows like a complex fluid with Herschel- Bulkley\nrheology. Microscopic plastic rearrangements and the emergence of their spatial\ncorrelations induce cooperativity flow behavior whose effect is pronounced in\npresence of confinement. With the help of lattice Boltzmann numerical\nsimulations of confined dense emulsions, we explore the role of geometrical\nroughness in providing activation of plastic events close to the boundaries. We\nprobe also the spatial configuration of the fluidity field, a continuum\nquantity which can be related to the rate of plastic events, thereby allowing\nus to establish a link between the mesoscopic plastic dynamics of the jammed\nmaterial and the macroscopic flow behaviour."
    },
    {
        "anchor": "Analysis of viscoelastic soft dielectric elastomer generators operating\n  in an electrical circuit: A predicting model for soft Dielectric Elastomer Generators (DEGs) must\nconsider a realistic model of the electromechanical behaviour of the elastomer\nfilling, the variable capacitor and of the electrical circuit connecting all\nelements of the device. In this paper such an objective is achieved by\nproposing a complete framework for reliable simulations of soft energy\nharvesters. In particular, a simple electrical circuit is realised by\nconnecting the capacitor, stretched periodically by a source of mechanical\nwork, in parallel with a battery through a diode and with an electrical load\nconsuming the energy produced. The electrical model comprises resistances\nsimulating the effect of the electrodes and of the conductivity current\ninvariably present through the dielectric film. As these devices undergo a high\nnumber of electro-mechanical loading cycles at large deformation, the\ntime-dependent response of the material must be taken into account as it\nstrongly affects the generator outcome. To this end, the viscoelastic behaviour\nof the polymer and the possible change of permittivity with strains are\nanalysed carefully by means of a proposed coupled electro-viscoelastic\nconstitutive model, calibrated on experimental data available in the literature\nfor an incompressible polyacrilate elastomer (3M VHB4910). Numerical results\nshowing the importance of time-dependent behaviour on the evaluation of\nperformance of DEGs for different loading conditions, namely equi-biaxial and\nuniaxial, are reported in the final section.",
        "positive": "Surface-induced layer formation in polyelectrolytes: We analyze, by means of an RPA calculation, the conditions under which a\nmixture of oppositely charged polyelectrolytes can micro-segregate in the\nneighborhood of a charged surface creating a layered structure. A number of\nstable layers can be formed if the surface is sufficiently strongly charged\neven at temperatures at which the bulk of the mixture is homogeneous."
    },
    {
        "anchor": "Hydrogen-bonded Silica Gels Dispersed in a Smectic Liquid Crystal: A\n  Random Field XY System: The effect on the nematic to smectic-A transition in octylcyanobiphenyl (8CB)\ndue to dispersions of hydrogen-bonded silica (aerosil) particles is\ncharacterized with high-resolution x-ray scattering. The particles form weak\ngels in 8CB creating a quenched disorder that replaces the transition with the\ngrowth of short range smectic correlations. The correlations include thermal\ncritical fluctuations that dominate at high temperatures and a second\ncontribution that quantitatively matches the static fluctuations of a random\nfield system and becomes important at low temperatures.",
        "positive": "Transport of Torsional Stress in DNA: It is well known that transcription can induce torsional stress in DNA,\naffecting the activity of nearby genes or even inducing structural transitions\nin the DNA duplex. It has long been assumed that the generation of significant\ntorsional stress requires the DNA to be anchored, forming a limited topological\ndomain, since otherwise it would spin almost freely about its axis. Previous\nestimates of the rotational drag have, however, neglected the role of small\nnatural bends in the helix backbone. We show how these bends can increase the\ndrag several thousandfold relative to prior estimates, allowing significant\ntorsional stress even in linear, unanchored DNA. The model helps explain\nseveral puzzling experimental results on structural transitions induced by\ntranscription of DNA."
    },
    {
        "anchor": "Local vs. Cooperative: Unraveling Glass Transition Mechanisms with SEER: Which phenomenon slows down the dynamics in super-cooled liquids and turns\nthem into glasses is a long-standing question of condensed-matter. Most popular\ntheories posit that as the temperature decreases, many events must occur in a\ncoordinated fashion on a growing length scale for relaxation to occur. Instead,\nother approaches consider that local barriers associated with the elementary\nrearrangement of a few particles or `excitations' govern the dynamics. To\nresolve this conundrum, our central result is to introduce an algorithm, SEER,\nwhich can systematically extract hundreds of excitations and their energy from\nany given configuration. We also provide a novel measurement of the activation\nenergy, characterizing the liquid dynamics, based on fast quenching and\nreheating. We use these two methods in a popular liquid model of polydisperse\nparticles. Such polydisperse models are known to capture the hallmarks of the\nglass transition and can be equilibrated efficiently up to millisecond time\nscales. The analysis reveals that cooperative effects do not control the\nfragility of such liquids: the change of energy of local barriers determines\nthe change of activation energy. More generally, these methods can now be used\nto measure the degree of cooperativity of any liquid model.",
        "positive": "Mechanical unfolding and refolding pathways of ubiquitin: Mechanical unfolding and refolding of ubiquitin are studied by Monte Carlo\nsimulations of a Go model with binary variables. The exponential dependence of\nthe time constants on the force is verified, and folding and unfolding lengths\nare computed, with good agreement with experimental results. Furthermore, the\nmodel exhibits intermediate kinetic states, as observed in experiments.\nUnfolding and refolding pathways and intermediate states, obtained by tracing\nsingle secondary structure elements, are consistent with simulations of\nprevious all-atom models and with the experimentally observed step sizes."
    },
    {
        "anchor": "Elasticity of Jammed Packings of Sticky Disks: Numerous soft materials jam into an amorphous solid at high packing fraction.\nThis non-equilibrium phase transition is best understood in the context of a\nmodel system in which particles repel elastically when they overlap. Recently,\nhowever, it was shown that introducing any finite amount of attraction between\nparticles changes the universality class of the transition. The properties of\nthis new ``sticky jamming'' class remain almost entirely unexplored. We use\nmolecular dynamics simulations and scaling analysis to determine the shear\nmodulus, bulk modulus, and coordination of marginal solids close to the sticky\njamming point. In each case, the behavior of the system departs sharply and\nqualitatively from the purely repulsive case.",
        "positive": "DNA self-assembly of single molecules with deterministic position and\n  orientation: An ideal nanofabrication method should allow the organization of\nnanoparticles and molecules with nanometric positional precision,\nstoichiometric control and well-defined orientation. The DNA origami technique\nhas evolved into a highly versatile bottom-up nanofabrication methodology that\nfulfils almost all of these features. It enables the nanometric positioning of\nmolecules and nanoparticles with stoichiometric control, and even the\norientation of asymmetrical nanoparticles along predefined directions. However,\norienting individual molecules has been a standing challenge, mainly due to\nunspecific electrostatic interactions. Here, we show how single molecules,\nnamely Cy5 and Cy3 fluorophores, can be incorporated in a DNA origami with\ncontrolled orientation by doubly linking them to oligonucleotide strands that\nare hybridized while leaving enough unpaired bases to induce a stretching\nforce. Particularly, we explore the effects of leaving 0, 2, 4, 6, and 8\nunpaired bases and find extreme orientations for 0 and 8 unpaired bases,\ncorresponding to the molecules being perpendicular and parallel to the DNA\ndouble helix, respectively. We foresee that these results will expand the\napplication field of DNA origami towards the fabrication of nanodevices\ninvolving a wide range of orientation-dependent molecular interactions, such as\nenergy transfer, intermolecular electron transport, catalysis, exciton\ndelocalization, or the electromagnetic coupling of a molecule to specific\nresonant nano-antennas modes."
    },
    {
        "anchor": "Swapping trajectories: a new wall-induced cross-streamline particle\n  migration mechanism in a dilute suspension of spheres: Binary encounters between spherical particles in shear flow are studied for a\nsystem bounded by a single planar wall or two parallel planar walls under\ncreeping flow conditions. We show that wall proximity gives rise to a new class\nof binary trajectories resulting in cross-streamline migration of the\nparticles. The spheres on these new trajectories do not pass each other (as\nthey would in free space) but instead they swap their cross-streamline\npositions. To determine the significance of the wall-induced particle\nmigration, we have evaluated the hydrodynamic self-diffusion coefficient\nassociated with a sequence of uncorrelated particle displacements due to binary\nparticle encounters. The results of our calculations quantitatively agree with\nthe experimental value obtained by \\cite{Zarraga-Leighton:2002} for the\nself-diffusivity in a dilute suspension of spheres undergoing shear flow in a\nCouette device. We thus show that the wall-induced cross-streamline particle\nmigration is the source of the anomalously large self-diffusivity revealed by\ntheir experiments.",
        "positive": "Conformal Smectics and their Many Metrics: We establish that equally-spaced smectic configurations enjoy an\ninfinite-dimensional conformal symmetry and show that there is a natural map\nbetween them and null hypersurfaces in maximally-symmetric spacetimes. By\nchoosing the appropriate conformal factor it is possible to restore additional\nsymmetries of focal structures only found before for smectics on flat\nsubstrates."
    },
    {
        "anchor": "The Chain Flexibility Effects on the Self-assembly of Diblock Copolymer\n  in Thin Film: We investigate the effects of chain flexibility on the self-assembly behavior\nof symmetric diblock copolymers (BCPs) when they are confined as a thin film\nbetween two surfaces. Employing worm-like chain (WLC) self-consistent field\ntheory, we study the relative stability of parallel (L$_{\\parallel}$) and\nperpendicular (L$_{\\perp}$) orientations of BCP lamellar phases, ranging in\nchain flexibility from flexible Gaussian chains to semi-flexible and rigid\nchains. For flat and neutral bounding surfaces (no surface preference for one\nof the two BCP components), the stability of the L$_{\\perp}$ lamellae increases\nwith chain rigidity. When the top surface is flat and the bottom substrate is\ncorrugated, increasing the surface roughness enhances the stability of the\nL$_{\\perp}$ lamellae for flexible Gaussian chains. However, an opposite\nbehavior is observed for rigid chains, where the L$_{\\perp}$ stability\ndecreases as the substrate roughness increases. We further show that as the\nsubstrate roughness increases, the critical value of the substrate preference,\n$u^{*}$, corresponding to an L$_{\\perp}$-to-L$_{\\parallel}$ transition,\ndecreases for rigid chains, while it increases for flexible Gaussian chains.\nOur results highlight the physical mechanism of tailoring the orientation of\nlamellar phases in thin-film setups. This is of importance, in particular, for\nshort (semi-flexible or rigid) chains that are in high demand in emerging\nnanolithography and other industrial applications.",
        "positive": "Mean first passage times for bond formation for a Brownian particle in\n  linear shear flow above a wall: Motivated by cell adhesion in hydrodynamic flow, here we study bond formation\nbetween a spherical Brownian particle in linear shear flow carrying receptors\nfor ligands covering the boundary wall. We derive the appropriate Langevin\nequation which includes multiplicative noise due to position-dependent mobility\nfunctions resulting from the Stokes equation. We present a numerical scheme\nwhich allows to simulate it with high accuracy for all model parameters,\nincluding shear rate and three parameters describing receptor geometry\n(distance, size and height of the receptor patches). In the case of homogeneous\ncoating, the mean first passage time problem can be solved exactly. In the case\nof position-resolved receptor-ligand binding, we identify different scaling\nregimes and discuss their biological relevance."
    },
    {
        "anchor": "Microscopic understanding of ion solvation in water: Solvation of ions is ubiquitous on our planet. Solvated ions have a profound\neffect on the behavior of ionic solutions, which is crucial in nature and\ntechnology. Experimentally, ions have been classified into \"structure makers\"\nor \"structure breakers\", depending on whether they slow down or accelerate the\nsolution dynamics. Theoretically, the dynamics of ions has been explained by a\ndielectric friction model combining hydrodynamics and charge-dipole interaction\nin the continuum description. However, both approaches lack a microscopic\nstructural basis, leaving the microscopic understanding of salt effects\nunclear. Here we elucidate unique microscopic features of solvation of\nspherical ions by computer simulations. We find that increasing the ion\nelectric field causes a sharp transitional decrease in the hydration-shell\nthickness, signaling the ion mobility change from the Stokes to dielectric\nfriction regime. The dielectric friction regime can be further divided into two\ndue to the competition between the water-water hydrogen bonding and ion-water\nelectrostatic interactions: Whether the former or latter prevails determines\nwhether the water dynamics are accelerated or decelerated. In the ion-water\ninteraction predominant regime, a specific combination of ion size and charge\nstabilizes the hydration shell via orientational-symmetry breaking, reminiscent\nof the Thomson problem for the electron configuration of atoms. Notably, the\nhydration-shell stability is much higher for a composite coordination number\nthan a prime one, a prime-number effect on solvent dynamics. These findings are\nfundamental to the structure breaker/maker concept and provide new insights\ninto the solvent structure and dynamics beyond the continuum model, paving the\nway towards a microscopic theory of ionic solutions.",
        "positive": "Core-shell structures in single flexible-semiflexible block copolymers:\n  Finding the free energy minimum for the folding transition: We investigate the folding transition of a single diblock copolymer\nconsisting of a semiflexible and a flexible block. We obtain a {\\it\nSaturn-shaped} core-shell conformation in the folded state, in which the\nflexible block forms a core and the semiflexible block wraps around it. We\ndemonstrate two distinctive features of the core-shell structures: (i) The\nkinetics of the folding transition in the copolymer are significantly more\nefficient than those of a semiflexible homopolymer. (ii) The core-shell\nstructure does not depend on the transition pathway."
    },
    {
        "anchor": "Influence of tangential displacement on the force of adhesion between a\n  parabolic profile and plane surface: The force of adhesion of a rotationally symmetric indenter and an elastic\nhalf-space is analyzed analytically and numerically using an extension of the\nmethod of dimensionality reduction (MDR) for superimposed normal/tangential\nadhesive contacts. In particular, the dependency of the critical adhesion force\non the simultaneously applied tangential force is obtained and the relevant\ndimensionless parameters of the problem are identified. The developed method is\napplicable straightforwardly to adhesive contacts of any bodies of revolution.",
        "positive": "Physical phase field model for phagocytosis: We propose and study a simple, physical model for phagocytosis, i.e. the\nactive, actin-mediated uptake of micron-sized particles by biological cells.\nThe cell is described by the phase field method and the driving mechanisms of\nuptake are actin ratcheting, modeled by a dynamic vector field, as well as\ncell-particle adhesion due to receptor-ligand binding. We first test the\nmodeling framework for the symmetric situation of a spherical cell engulfing a\nfixed spherical particle. We then exemplify its versatility by studying various\nasymmetric situations like different particle shapes and orientations, as well\nas the simultaneous uptake of two particles. In addition, we perform a\nperturbation theory of a slightly modified model version in the symmetric\nsetting, allowing to derive a reduced model, shedding light on the effective\ndriving forces and being easier to solve. This work is meant as a first step in\ndescribing phagocytosis and we discuss several effects that are amenable to\nfuture modeling within the same framework."
    },
    {
        "anchor": "Calorimetric study of the nematic to smectic-\\textit{A} and\n  smectic-\\textit{A} to smectic-\\textit{C} phase transitions in\n  liquid-crystal+aerosil dispersions: A high-resolution calorimetric study has been carried out on nano-colloidal\ndispersions of aerosils in the liquid crystal\n4-\\textit{n}-pentylphenylthiol-4'-\\textit{n}-octyloxybenzoate ($\\bar{8}$S5) as\na function of aerosil concentration and temperature spanning the\nsmectic-\\textit{C} to nematic phases. Over this temperature range, this liquid\ncrystal possesses two continuous XY phase transitions: a fluctuation dominated\nnematic to smectic-\\textit{A} transition with $\\alpha \\approx \\alpha_{XY} =\n-0.013$ and a mean-field smectic-\\textit{A} to smectic-\\textit{C} transition.\nThe effective critical character of the \\textit{N}-Sm\\textit{A} transition\nremains unchanged over the entire range of introduced quenched random disorder\nwhile the peak height and enthalpy can be well described by considering a\ncut-off length scale to the quasi-critical fluctuations. The robust nature of\nthe \\textit{N}-Sm\\textit{A} transition in this system contrasts with\ncyanobiphenyl-aerosil systems and may be due to the mesogens being non-polar\nand having a long nematic range. The character of the Sm\\textit{A}-Sm\\textit{C}\ntransition changes gradually with increasing disorder but remains\nmean-field-like. The heat capacity maximum at the Sm\\textit{A}-Sm\\textit{C}\ntransition scales as $\\rho_S^{-0.5}$ with an apparent evolution from\ntricritical to a simple mean-field step behavior. These results may be\ngenerally understood as a stiffening of the liquid crystal (both the nematic\nelasticity as well as the smectic layer compression modulus $B$) with silica\ndensity.",
        "positive": "Kinetics of Ordering in Fluctuation-Driven First-Order Transitions:\n  Simulations and Dynamical Renormalization: Many systems where interactions compete with each other or with constraints\nare well described by a model first introduced by Brazovskii. Such systems\ninclude block copolymers, alloys with modulated phases, Rayleigh-Benard Cells\nand type-I superconductors. The hallmark of this model is that the fluctuation\nspectrum is isotropic and has a minimum at a nonzero wave vector represented by\nthe surface of a d-dimensional hyper-sphere. It was shown by Brazovskii that\nthe fluctuations change the free energy structure from a $ \\phi ^{4}$ to a\n$\\phi ^{6}$ form with the disordered state metastable for all quench depths.\nThe transition from the disordered to the periodic, lamellar structure changes\nfrom second order to first order and suggests that the dynamics is governed by\nnucleation. Using numerical simulations we have confirmed that the equilibrium\nfree energy function is indeed of a $ \\phi ^{6}$ form. A study of the dynamics,\nhowever, shows that, following a deep quench, the dynamics is described by\nunstable growth rather than nucleation. A dynamical calculation, based on a\ngeneralization of the Brazovskii calculations shows that the disordered state\ncan remain unstable for a long time following the quench."
    },
    {
        "anchor": "Instability of the symmetric Couette-flow in a granular gas:\n  hydrodynamic field profiles and transport: We investigate the inelastic hard disk gas sheared by two parallel bumpy\nwalls (Couette-flow). In our molecular dynamic simulations we found a\nsensitivity to the asymmetries of the initial condition of the particle places\nand velocities and an asymmetric stationary state, where the deviation from\n(anti)symmetric hydrodynamic fields is stronger as the normal restitution\ncoefficient decreases. For the better understanding of this sensitivity we\ncarried out a linear stability analysis of the former kinetic theoretical\nsolution [Jenkins and Richman: J. Fluid. Mech. {\\bf 171} (1986)] and found it\nto be unstable. The effect of this asymmetry on the self-diffusion coefficient\nis also discussed.",
        "positive": "Self-diffusiophoresis induced by fluid interfaces: The influence of a fluid-fluid interface on self-phoresis of chemically\nactive, axially symmetric, spherical colloids is analyzed. Distinct from the\nstudies of self-phoresis for colloids trapped at fluid interfaces or in the\nvicinity of hard walls, here we focus on the issue of self-phoresis close to a\nfluid-fluid interface. In order to provide physically intuitive results\nhighlighting the role played by the interface, the analysis is carried out for\nthe case that the symmetry axis of the colloid is normal to the interface;\nmoreover, thermal fluctuations are not taken into account. Similarly to what\nhas been observed near hard walls, we find that such colloids can be set into\nmotion even if their whole surface is homogeneously active. This is due to the\nanisotropy along the direction normal to the interface owing to the\npartitioning by diffusion, among the coexisting fluid phases, of the product of\nthe chemical reaction taking place at the colloid surface. Different from\nresults corresponding to hard walls, in the case of a fluid interface the\ndirection of motion, i.e., towards the interface or away from it, can be\ncontrolled by tuning the physical properties of one of the two fluid phases.\nThis effect is analyzed qualitatively and quantitatively, both by resorting to\na far-field approximation and via an exact, analytical calculation which\nprovides the means for a critical assessment of the approximate analysis."
    },
    {
        "anchor": "Multi-chain slip-spring simulations with various slip-spring densities: Although it has been established that the multi-chain slip-spring (MCSS)\nmodel can reproduce entangled polymer dynamics, the effects of model parameters\nhave not been fully elucidated yet. In this study, we systematically\ninvestigated the effects of slip-spring density. For the diffusion and the\nlinear viscoelasticity, the simulation results exhibited universality. Namely,\nthe results from the simulations with various slip-spring densities can be\nsuperposed with each other by the conversion factors for the bead number per\nchain, unit of length, unit of time, and modulus. The diffusion and the\nviscoelasticity were in good agreement with the literature data for the\nstandard bead-spring simulations, including the molecular weight dependence.\nThe universality among the MCSS simulations with various slip-spring density\nalso held under mild shear if the slip-spring density was not significantly\nhigh. The results imply that the level of coarse-graining for the MCSS model\ncan be arbitrarily chosen as in the Rouse model.",
        "positive": "Theory of defect-mediated morphogenesis: Growing experimental evidence indicates that topological defects could serve\nas organizing centers in the morphogenesis of tissues. Here, we provide a\nquantitative explanation for this phenomenon, rooted in the buckling theory of\ndeformable active polar liquid crystals. Using a combination of linear\nstability analysis and computational fluid dynamics, we demonstrate that active\nlayers, such as confined cell monolayers, are unstable to the formation of\nprotrusions in the presence of disclinations. The instability originates from\nan interplay between the focusing of the elastic forces, mediated by defects,\nand the renormalization of the system's surface tension by the active flow. The\nposttransitional regime is also characterized by several complex\nmorphodynamical processes, such as oscillatory deformations, droplet\nnucleation, and active turbulence. Our findings offer an explanation of recent\nobservations on tissue morphogenesis and shed light on the dynamics of active\nsurfaces in general."
    },
    {
        "anchor": "Creep and fluidization in thermal amorphous solids: When submitted to a constant mechanical load, many amorphous solids display\npower law creep followed by fluidization. A fundamental understanding of these\nprocesses is still far from being achieved. Here, we characterize creep and\nfluidization on the basis of a mesoscopic viscoplastic model that includes\nthermally activated yielding events and a broad distribution of energy\nbarriers, which may be lowered under the effect of a local deformation. We\nrelate the creep exponent observed before fluidization to the width of barrier\ndistribution and to the specific form of stress redistribution following\nyielding events. We show that Andrade creep is accompanied by local\nstrain-hardening driven by stress redistribution and find that the fluidization\ndepends exponentially on the applied stress. The simulation results are\ninterpreted in the light of a mean-field analysis, and should help in\nrationalizing the creep phenomenology of amorphous solids.",
        "positive": "Dynamics of unbinding of polymers in a random medium: We have studied the aging effect on the dynamics of unbinding of a double\nstranded directed polymer in a random medium. By using the Monte Carlo dynamics\nof a lattice model in two dimensions, for which disorder is known to be\nrelevant, the unbinding dynamics is studied by allowing the bound polymer to\nrelax in the random medium for a waiting time and then allowing the two strands\nto unbind. The subsequent dynamics is formulated in terms of the overlap of the\ntwo strands and also the overlap of each polymer with the configuration at the\nstart of the unbinding process. The interrelations between the two and the\nnature of the dependence on the waiting time are studied."
    },
    {
        "anchor": "Base pair fluctuations in helical models for nucleic acids: A statistical method is developed to estimate the maximum amplitude of the\nbase pair fluctuations in a three dimensional mesoscopic model for nucleic\nacids. The base pair thermal vibrations around the helix diameter are viewed as\na Brownian motion for a particle embedded in a stable helical structure. The\nprobability to return to the initial position is computed, as a function of\ntime, by integrating over the particle paths consistent with the physical\nproperties of the model potential. The zero time condition for the\nfirst-passage probability defines the constraint to select the integral cutoff\nfor various macroscopic helical conformations, obtained by tuning the twist,\nthe bending and the slide motion between adjacent base pairs along the molecule\nstack. Applying the method to a short homogeneous chain at room temperature, we\nobtain meaningful estimates for the maximum fluctuations in the twist\nconformation with $\\sim 10.5$ base pairs per helix turn, typical of double\nstranded DNA helices. Untwisting the double helix, the base pair fluctuations\nbroaden and the integral cutoff grows. The cutoff is found to increase also in\nthe presence of a sliding motion which shortens the helix contour length, a\nsituation peculiar of dsRNA molecules.",
        "positive": "Topological Defects in Ferromagnetic, Antiferromagnetic and Cyclic\n  Spinor Condensates -- A Homotopy Theory: We apply the homotopy group theory in classifying the topological defects in\natomic spin-1 and spin-2 Bose-Einstein condensates. The nature of the defects\ndepends crucially on the spin-spin interaction between the atoms. We find the\ntopologically stable defects both for spin-1 ferromagnetic and\nanti-ferromagnetic states, and for spin-2 ferromagnetic and cyclic states. With\nthis rigorous approach we clarify the previously controversial identification\nof symmetry groups and order parameter spaces for the spin-1 anti-ferromagnetic\nstate, and show that the spin-2 cyclic case provides a rare example of a\nphysical system with non-Abelian line defects, like those observed in biaxial\nnematics. We also show the possibility to produce vortices with fractional\nwinding numbers of 1/2, 1/3 and their multiples in spinor condensates."
    },
    {
        "anchor": "Polarization of active Janus particles: We study the collective motion of Janus particles in a temperature or\nconcentration gradient. Because of the torque exerted by an external or\nself-generated field, the particles align their axis on this gradient. In a\nswarm of self-driven particles, this polarization enhances the\ninteractiondriven confinement. Self-polarization in a non-uniform laser beam\ncould be used for guiding hot particles along a given trajectory.",
        "positive": "Acoustic emission signals resulting from the drying induced fractures of\n  Phyllostachys Pubescens bamboo, Evidence of scale free phenomena: I have performed experimental measurements of acoustic emission signals\nresulting from the drying process of Phyllostachys Pubescens bamboo. The\nemphasis was on identifying individual events, and characterize them according\nto their time span and energy release. My results show a histogram of\nexperimental squared voltage distributions nicely fit into a power law with\nexponent of $-1.16$, reminiscent of scale free phenomena. I have also\ncalculated the average signal shape, for different time spans of the system,\nand found an asymmetrical form. The experimental evidence points to the system\nhaving an isolated large crack at the beginning of the simulation."
    },
    {
        "anchor": "Anisotropic Mobility Model for Polymers under Shear and its Linear\n  Response Functions: We propose a simple dynamic model of polymers under shear with an anisotropic\nmobility tensor. We calculate the shear viscosity, the rheo-dielectric response\nfunction, and the parallel relaxation modulus under shear flow deduced from our\nmodel. We utilize recently developed linear response theories for\nnonequilibrium systems to calculate linear response functions. Our results are\nqualitatively consistent with experimental results. We show that our\nanisotropic mobility model can reproduce essential dynamical nature of polymers\nunder shear qualitatively. We compare our model with other models or theories\nsuch as the convective constraint release model or nonequilibrium linear\nresponse theories.",
        "positive": "Equilibrium cluster phases and low-density arrested disordered states:\n  The role of short-range attraction and long-range repulsion: We study a model in which particles interact with short-ranged attractive and\nlong-ranged repulsive interactions, in an attempt to model the equilibrium\ncluster phase recently discovered in sterically stabilized colloidal systems in\nthe presence of depletion interactions. At low packing fraction particles form\nstable equilibrium clusters which act as building blocks of a cluster fluid. We\nstudy the possibility that cluster fluids generate a low-density disordered\narrested phase, a gel, via a glass transition driven by the repulsive\ninteraction. In this model the gel formation is formally described with the\nsame physics of the glass formation."
    },
    {
        "anchor": "Dissipative Dynamics of a Single Polymer in Solution: A Lowe-Andersen\n  Approach: We study the equilibrium dynamics of a single polymer chain under good\nsolvent condition. Special emphasis is laid on varying the drag force\nexperienced by the chain while it moves. To this end we model the solvent in a\nmesoscopic manner by employing the Lowe-Andersen approach of dissipative\nparticle dynamics which is known to reproduce hydrodynamic effects. Our\napproach captures the correct static behavior in equilibrium. Regarding the\ndynamics, we investigate the scaling of the self-diffusion coefficient $D$ with\nrespect to the length of the polymer $N$, yielding results that are compatible\nwith the Zimm scaling $D \\sim N^{-3/5}$.",
        "positive": "Discontinuous Shear Thickening of Frictional Hard-Sphere Suspensions: Discontinuous shear thickening (DST) observed in many dense athermal\nsuspensions has proven difficult to understand and to reproduce by numerical\nsimulation. By introducing a numerical scheme including both relevant\nhydrodynamic interactions and granularlike contacts, we show that contact\nfriction is essential for having DST. Above a critical volume fraction, we\nobserve the existence of two states: a low viscosity, contactless (hence,\nfrictionless) state, and a high viscosity frictional shear jammed state. These\ntwo states are separated by a critical shear stress, associated with a critical\nshear rate where DST occurs. The shear jammed state is reminiscent of the\njamming phase of granular matter. Continuous shear thickening is seen as a\nlower volume fraction vestige of the jamming transition."
    },
    {
        "anchor": "What is liquid in random porous media: the Barker-Henderson perturbation\n  theory: We apply the Barker-Henderson (BH) perturbation theory to the study of a\nLennard-Jones fluid confined in a random porous matrix formed by hard sphere\nparticles. In order to describe the reference system needed in this\nperturbation scheme, the extension of the scaled particle theory (SPT) is used.\nThe recent progress in the development of SPT approach for a hard sphere fluid\nin a hard sphere matrix allows us to obtain very accurate results for\nthermodynamic properties in such a system. Hence, we combine the BH\nperturbation theory with the SPT approach to derive expressions for the\nchemical potential and the pressure of a confined fluid. Using the obtained\nexpressions, the liquid-vapour phase diagrams of a LJ fluid in HS matrix are\nbuilt from the phase equilibrium conditions. Therefore, the effect of matrix\nporosity and a size of matrix particles is considered. It is shown that a\ndecrease of matrix porosity lowers both the critical temperature and the\ncritical density, while the phase diagram becomes narrower. An increase of a\nsize of matrix particles leads to an increase of the critical temperature. From\nthe comparison it is observed that the results obtained from the theory are in\nagreement with computer simulations. The approach proposed in the present study\ncan be extended to the case of anisotropic fluid particles in HS matrices.",
        "positive": "Ultrasonic wave transport in concentrated disordered resonant emulsions: We show how resonant (near-field) coupling affects wave transport in\ndisordered media through ultrasonic experiments in concentrated suspensions.\nThe samples consist of resonant emulsions in which oil droplets are suspended\nin a liquid gel. By varying the droplet concentration, the limits of the\nIndependent Scattering Approximation are experimentally demonstrated. For the\nmost concentrated samples, the proximity of resonant scatterers induces a\nrenormalization of the surrounding medium, leading to a reducing of scattering\nstrength. We point out an optimal volume fraction of oil droplets for which\nnon-diffusive wave transport is experimentally demonstrated. Our demonstration\nof maximum scattering at an intermediate droplet concentration is very relevant\nfor designing materials for the study of wave transport phenomena such as\nAnderson Localization."
    },
    {
        "anchor": "Solvent-free coarse-grained lipid model for large-scale simulations: A coarse-grained molecular model, which consists of a spherical particle and\nan orientation vector, is proposed to simulate lipid membrane on a large length\nscale. The solvent is implicitly represented by an effective attractive\ninteraction between particles. A bilayer structure is formed by\norientation-dependent (tilt and bending) potentials. In this model, the\nmembrane properties (bending rigidity, line tension of membrane edge, area\ncompression modulus, lateral diffusion coefficient, and flip-flop rate) can be\nvaried over broad ranges. The stability of the bilayer membrane is investigated\nvia droplet-vesicle transition. The rupture of the bilayer and worm-like\nmicelle formation can be induced by an increase in the spontaneous curvature of\nthe monolayer membrane.",
        "positive": "The microscopic pathway to crystallization in supercooled liquids: Despite its fundamental and technological importance, a microscopic\nunderstanding of the crystallization process is still elusive. By computer\nsimulations of the hard-sphere model we reveal the mechanism by which thermal\nfluctuations drive the transition from the supercooled liquid state to the\ncrystal state. In particular we show that fluctuations in bond orientational\norder trigger the nucleation process, contrary to the common belief that the\ntransition is initiated by density fluctuations. Moreover, the analysis of bond\norientational fluctuations shows that these not only act as seeds of the\nnucleation process, but also i) determine the particular polymorph which is to\nbe nucleated from them and ii) at high density favour the formation of fivefold\nstructures which can frustrate the formation of crystals. These results can\nshed new light on our understanding of the relationship between crystallization\nand vitrification."
    },
    {
        "anchor": "A Model for the Optical Absorption in Porous Silicon Quantum Wires: In this paper, we analyse the optical absorption in porous silicon . This is\nthe first attempt to explicitly demonstrate that it is not possible to extract\nthe band gap of such low dimensional nanostructures like porous silicon from a\nTauc plot of Square Root(alpha h nu) vs (h nu) . These objections are also\nvalid for other reduced dimensional systems like quantum wires and quantum dots\netc.\n  So we model the absorption process assuming that porous silicon is a pseudo\n1D material system having a distribution of band gaps. We show that in order to\nexplain the absorption we specifically need to invoke - (a) k is not conserved\nin optical transitions,(b) the oscillator strength of these transitions depends\non the size of the nanostructure in which the absorption takes place and (c)\nthe distribution of band gaps significantly influences the optical absorption.\nA natural explanation of the temperature dependence of absorption in porous\nsilicon also follows from our model . We have also shown that porosity can be\ninferred non-destructively from transmission measurements in the region of low\nabsorption.\n  One can easily generalize our equations and use them to analyse the\nabsorption process of other low dimensional materials too .",
        "positive": "Solidity of viscous liquids. IV. Density fluctuations: This paper is the fourth in a series exploring the physical consequences of\nthe solidity of highly viscous liquids. It is argued that the two basic\ncharacteristics of a flow event (a jump between two energy minima in\nconfiguration space) are the local density change and the sum of all particle\ndisplacements. Based on this it is proposed that density fluctuations are\ndescribed by a time-dependent Ginzburg-Landau equation with rates in k-space of\nthe form $\\Gamma_0+Dk^2$ with $D\\gg\\Gamma_0a^2$ where $a$ is the average\nintermolecular distance. The inequality expresses a long-wavelength dominance\nof the dynamics which implies that the Hamiltonian (free energy) may be taken\nto be ultra local. As an illustration of the theory the case with the simplest\nnon-trivial Hamiltonian is solved to second order in the Gaussian\napproximation, where it predicts an asymmetric frequency dependence of the\nisothermal bulk modulus with Debye behavior at low frequencies and an\n$\\omega^{-1/2}$ decay of the loss at high frequencies. Finally, a general\nformalism for the description of viscous liquid dynamics, which supplements the\ndensity dynamics by including stress fields, a potential energy field, and\nmolecular orientational fields, is proposed."
    },
    {
        "anchor": "Side-wall pressure distribution of granular silos: The side-wall pressure distribution in static silos is an important and open\nproblem related to storage safety of granular materials. Referring to Lvin's\ntheory [Powder Technology 4, 280 (1971)] and Rodolfo's 2D numerical result\n[Phys. Rev. E 97.1(2018)], a new theoretical model of side wall pressure is\nestablished by assuming the friction coefficient as well as the ratio of\nhorizontal to vertical stress changing with depth position in silo.\nFurthermore, the transition of stress state between hydrostatic-like and\nJanssen-like is systematically investigated by our model and experiment, and\nfinally an empirical expression describing this transition is proposed.",
        "positive": "Local melting attracts grain boundaries in colloidal polycrystals: We find that laser-induced local melting attracts and deforms grain\nboundaries in 2D colloidal crystals. When a melted region in contact with the\nedge of a crystal grain recrystallizes, it deforms the grain boundary --- this\nattraction is driven by the multiplicity of deformed grain boundary\nconfigurations. Furthermore, the attraction provides a method to fabricate\nartificial colloidal crystal grains of arbitrary shape, enabling new\nexperimental studies of grain boundary dynamics and ultimately hinting at a\nnovel approach for fabricating materials with designer microstructures."
    },
    {
        "anchor": "Curvature as a guiding field for patterns in thin block copolymer films: Experimental data on thin films of cylinder-forming block copolymers (BC) --\nfree-standing BC membranes as well as supported BC films -- strongly suggest\nthat the local orientation of the BC patterns is coupled to the geometry in\nwhich the patterns are embedded. We analyze this phenomenon using general\nsymmetry considerations and numerical self-consistent field studies of curved\nBC films in cylindrical geometry. The stability of the films against\ncurvature-induced dewetting is also analyzed. In good agreement with\nexperiments, we find that the BC cylinders tend to align along the direction of\ncurvature at high curvatures. At low curvatures, we identify a transition from\nperpendicular to parallel alignment in supported films, which is absent in free\nstanding membranes. Hence both experiments and theory show that curvature can\nbe used to manipulate and align BC patterns.",
        "positive": "Non-Appearance of Vortices in Fast Mechanical Expansions of Liquid 4He\n  Through the Lambda Transition: A new experiment has been performed to study the formation of topological\ndefects (quantized vortices) during rapid quenches of liquid 4He through the\nsuperfluid transition, with particular care taken to minimise vortex creation\nvia conventional hydrodynamic flow processes. It is found that the generated\nvortices, if any, are being produced at densities at least two orders of\nmagnitude less than might be expected on the basis of the Kibble-Zurek\nmechanism."
    },
    {
        "anchor": "Diffusivity and Weak Clustering in a Quasi 2D Granular Gas: We present results from a detailed simulation of a quasi-2D dissipative\ngranular gas, kept in a non-condensed steady state via vertical shaking over a\nrough substrate. This gas shows a weak power-law decay in the tails of its Pair\nDistribution Functions (PDF's), indicating fractality and therefore a tendency\nto form clusters over several size scales. This clustering depends\nmonotonically on the dissipation coefficient, and disappears when the\nsphere-sphere collisions are conservative. Clustering is also sensitive to the\npacking fraction. This gas also displays the standard nonequilibrium\ncharacteristics of similar systems, including non-Maxwellian velocity\ndistributions. The diffusion coefficients are calculated over all the\nconditions of the simulations, and it is found that diluted gases are more\ndiffusive for smaller restitution coefficients.",
        "positive": "Granular Response to Impact: Topology of the Force Networks: Impact of an intruder on granular matter leads to formation of mesoscopic\nforce networks seen particularly clearly in the recent experiments carried out\nwith photoelastic particles, e.g., Clark et al., Phys. Rev. Lett., 114 144502\n(2015). These force networks are characterized by complex structure and evolve\non fast time scales. While it is known that total photoelastic activity in the\ngranular system is correlated with the acceleration of the intruder, it is not\nknown how the structure of the force network evolves during impact, and if\nthere is a dominant features in the networks that can be used to describe\nintruder's dynamics. Here, we use topological tools, in particular persistent\nhomology, to describe these features. Persistent homology allows quantification\nof both structure and time evolution of the resulting force networks. We find\nthat there is a clear correlation of the intruder's dynamics and some of the\ntopological measures implemented. This finding allows us to discuss which\nproperties of the force networks are most important when attempting to describe\nintruder's dynamics. Regarding temporal evolution of the networks, we are able\nto define the upper bound on the relevant time scale on which the networks\nevolve."
    },
    {
        "anchor": "Coexistence of nonequilibrium phases in assemblies of driven nematic\n  colloids: We combine experiments, theory, and simulations to investigate the\ncoexistence of nonequilibrium phases emerging from interacting colloidal\nparticles that are electrokinetically propelled in a nematic liquid crystal\nsolvent. We directly determine the mechanical pressure within the radial\nassemblies and measure a non-equilibrium equation of state for this athermal\ndriven system. A generic model combines phoretic propulsion with the interplay\nbetween electrostatic effects and liquid-crystal-mediated hydrodynamics, which\nare effectively cast into a long-range interparticle repulsion, while\nelasticity plays a subdominant role. Simulations based on this model explain\nthe observed collective organization process and phase coexistence\nquantitatively. Our colloidal assemblies provide an experimental test-bed to\ninvestigate the fundamental role of phoretic pressure in the organization of\ndriven out-of-equilibrium matter.",
        "positive": "Irreversible Incremental Behavior in a Granular Material: We test the elasticity of granular aggregates using increments of shear and\nvolume strain in a numerical simulation. We find that the increment in volume\nstrain is almost reversible, but the increment in shear strain is not. The\nstrength of this irreversibility increases as the average number of contacts\nper particle (the coordination number) decreases. For increments of volume\nstrain, an elastic model that includes both average and fluctuating motions\nbetween contacting particles reproduces well the numerical results over the\nentire range of coordination numbers. For increments of shear strain, the\ntheory and simulations agree quite well for high values of the coordination\nnumber."
    },
    {
        "anchor": "Rotational directionality via symmetry-breaking in an electrostatic\n  motor: We theoretically investigate how one can achieve a preferred rotational\ndirection for the case of a simple electrostatic motor. The motor is composed\nby a rotor and two electronic reservoirs. Electronic islands on the rotor can\nexchange electrons with the reservoirs. An electrostatic field exerts a force\non the occupied islands. The charge dynamics and the electrostatic field drive\nrotations of the rotor. Coupling to an environment lead to damping on the\nrotational degree of freedom. We use two different approaches to the charge\ndynamics in the electronic islands: hopping process and mean-field. The hopping\nprocess approach takes into account charge fluctuations, which can appear along\nCoulomb blockade effects in nanoscale systems. The mean-field approach neglects\nthe charge fluctuations on the islands, which is typically suitable for larger\nsystems. We show that for a system described by the mean-field equations one\ncan in principle prepare initial conditions to obtain a desired rotational\ndirection. In contrast, this is not possible in the stochastic description.\nHowever, for both cases one can achieve rotational directionality by changing\nthe geometry of the rotor. By scanning the space formed by the relevant\ngeometric parameters we find optimal geometries, while fixing the dissipation\nand driving parameters. Remarkably, in the hopping process approach perfect\nrotational directionality is possible for a large range of geometries.",
        "positive": "Onset of Irreversibility in Cyclic Shear of Granular Packings: We investigate the onset of irreversibility in a dense granular medium\nsubjected to cyclic shear in a split-bottom geometry. To probe the micro and\nmesoscale we image bead trajectories in 3D throughout a series of shear strain\noscillations. Though beads lose and regain contact with neighbors during a\ncycle, the topology of the contact network exhibits reversible properties for\nsmall oscillation amplitudes. With increasing reversal amplitude a transition\nto an irreversible diffusive regime occurs."
    },
    {
        "anchor": "Active Spaghetti: Collective Organization in Cyanobacteria: Filamentous cyanobacteria can show fascinating examples of nonequilibrium\nself-organization, which however are not well-understood from a physical\nperspective. We investigate the motility and collective organization of\ncolonies of these simple multicellular lifeforms. As their area density\nincreases, linear chains of cells gliding on a substrate show a transition from\nan isotropic distribution to bundles of filaments arranged in a reticulate\npattern. Based on our experimental observations of individual behavior and\npairwise interactions, we introduce a nonreciprocal model accounting for the\nfilaments' large aspect ratio, fluctuations in curvature, motility, and nematic\ninteractions. This minimal model of active filaments recapitulates the\nobservations, and rationalizes the appearance of a characteristic lengthscale\nin the system, based on the Peclet number of the cyanobacteria filaments.",
        "positive": "Phase stability of dispersions of hollow silica nanocubes mediated by\n  non-adsorbing polymers: Although there are theoretical predictions [\\textit{Eur.~Phys.~J.~E}\n\\textbf{41} (2018) 110] for the rich phase behaviour of colloidal cubes mixed\nwith non-adsorbing polymers, a thorough verification of this phase behaviour is\nstill underway; experimental studies on mixtures of cubes and non-adsorbing\npolymers in bulk are scarce. In this paper, mixtures of hollow silica nanocubes\nand linear polystyrene in \\textit{N,-N-}dimethylformamide are used to measure\nthe structure factor of the colloidal cubes as a function of non-adsorbing\npolymer concentration. Together with visual observations these structure\nfactors enabled us to assess the depletion-mediated phase stability of\ncube-polymer mixtures. The theoretical and experimental phase boundaries for\ncube-depletant mixtures are in remarkable agreement, despite the\nsimplifications underlying the theory employed."
    },
    {
        "anchor": "Biaxial nematic phase stability and demixing behaviour in monolayers of\n  rod-plate mixtures: We theoretically study the phase behaviour of monolayers of hard rod-plate\nmixtures using a fundamental-measure density functional in the\nrestricted-orientation (Zwanzig) approximation. We consider both species to be\nsubject to an attractive potential proportional to the particle contact area on\nthe surface and with adsorption strengths that depend on the species type.\nParticles have board-like shape, with sizes chosen using a symmetry criterion:\nsame volume and same aspect ratio $\\kappa$. Phase diagrams were calculated for\n$\\kappa=10$, 20 and 40 and different values of adsorption strengths. For small\nadsorption strengths the mixtures exhibit a second-order uniaxial\nnematic-biaxial nematic transition for molar fraction of rods $0\\leq x\\lesssim\n0.9$. In the uniaxial nematic phase the particle axes of rods and plates are\naligned perpendicular and parallel to the monolayer, respectively. At the\ntransition, the orientational symmetry of the plate axes is broken, and they\norient parallel to a director lying on the surface. For large and equal\nadsorption strengths the mixture demixes at low pressures into a uniaxial\nnematic phase, rich in plates, and a biaxial nematic phase, rich in rods. This\ndemixing is located between two tricritical points. Also, at higher pressures\nand in the plate-rich part of the phase diagram, the system exhibits a strong\nfirst-order uniaxial nematic-biaxial nematic phase transition with a large\ndensity coexistence gap. When rod adsorption is considerably large while that\nof plates is small, the transition to the biaxial nematic phase is always of\nsecond order. At very high pressures the mixture can effectively be identified\nas a two-dimensional mixture of squares and rectangles which again demixes\nabove a certain critical point. We also studied the relative stability of\nuniform phases with respect to density modulations of smectic, columnar and\ncrystalline symmetry.",
        "positive": "Hexatic phase and water-like anomalies in a two-dimensional fluid of\n  particles with a weakly softened core: We study a two-dimensional fluid of particles interacting through a\nspherically-symmetric and marginally soft two-body repulsion. This model can\nexist in three different crystal phases, one of them with square symmetry and\nthe other two triangular. We show that, while the triangular solids first melt\ninto a hexatic fluid, the square solid is directly transformed on heating into\nan isotropic fluid through a first-order transition, with no intermediate\ntetratic phase. In the low-pressure triangular and square crystals melting is\nreentrant provided the temperature is not too low, but without the necessity of\ntwo competing nearest-neighbor distances over a range of pressures. A whole\nspectrum of water-like fluid anomalies completes the picture for this model\npotential."
    },
    {
        "anchor": "Crossover from normal to anomalous diffusion in field-aligned dipolar\n  systems: Using molecular dynamics simulations we investigate the translational\ndynamics of particles with dipolar interactions in homogenous external fields.\nFor a broad range of concentrations, we find that the anisotropic, yet normal\ndiffusive behavior characterizing weakly coupled systems becomes anomalous both\nparallel and perpendicular to the field at sufficiently high dipolar coupling\nand field strength. After the ballistic regime, chain formation first yields\ncage-like motion in all directions, followed by transient, mixed\ndiffusive-superdiffusive behavior resulting from cooperative motion of the\nchains. The enhanced dynamics disappears only at higher densities close to\ncrystallization.",
        "positive": "Morphology of soft and slippery contact via fluid drainage: The dynamic of contact formation between soft materials immersed in a fluid\nis accompanied by fluid drainage and elastic deformation. As a result,\ncontrolling the coupling between lubrication pressure and elasticity provides\nstrategies to design materials with reversible and dynamic adhesion to wet or\nflooded surfaces. We characterize the elastic deformation of a soft coating\nwith nanometer-scale roughness as it approaches and contacts a rigid surface in\na fluid environment. The lubrication pressure during the approach causes\nelastic deformation and prevents contact formation. We observe deformation\nprofiles that are drastically different from those observed for elastic\nhalf-space when the thickness of the soft coating is comparable to the\nhydrodynamic radius. In contrast, we show that surface roughness favors fluid\ndrainage without altering the elastic deformation. As a result, the coupling\nbetween elasticity and slip (caused by surface roughness) can lead to trapped\nfluid pockets in the contact region."
    },
    {
        "anchor": "Unveiling the complex glassy dynamics of square shoulder systems:\n  simulations and theory: We performed extensive molecular dynamics (MD) simulations, supplemented by\nMode Coupling Theory (MCT) calculations, for the Square Shoulder (SS) model, a\npurely repulsive potential where the hard-core is complemented by a finite\nshoulder. For the one-component version of this model, MCT predicted [Sperl\n{\\it et al.} Phys. Rev. Lett. {\\bf 104}, 145701 (2010)] the presence of\ndiffusion anomalies both upon cooling and upon compression and the occurrence\nof glass-glass transitions. In the simulations, we focus on a non-crystallising\nbinary mixture, which, at the investigated shoulder width, shows a\nnon-monotonic behaviour of the diffusion upon cooling but not upon isothermal\ncompression. In addition, we find the presence of a disconnected glass-glass\nline in the phase diagram, ending in two higher-order singularities. These\npoints generate a logarithmic dependence of the density correlators as well as\na subdiffusive behaviour of the mean squared displacement, although with the\ninterference of the nearby liquid-glass transition. We also perform novel MCT\ncalculations using as input the partial structure factors obtained within MD,\nconfirming the simulation results. The presence of two hard sphere glasses,\ndiffering only in their hard core length, is revealed, showing that the simple\ncompetition between the two is sufficient for creating a rather complex\ndynamical behaviour.",
        "positive": "Influence of C$_{6}$H$_{4}$(OH)$_{2}$ isomers on water disinfection by\n  photocatalysis: a computational study: Solar disinfection by photocatalysis is one of the promising methods used for\ndrinking water disinfection. It leads to the destruction of bacteria like\n$Escherichia$ $Coli$ ($E.$ $Coli$). In this paper, we compare our theoretical\nresults with experimental ones done previously by A.G. Rinc\\'on and his\ncolleagues concerning the order of decay of C$_{6}$H$_{4}$(OH)$_{2}$ isomers in\nthe presence of titanium dioxide TiO$_{2}$, and show the influence of optical\nproperties of those molecules on $E.$ $Coli$ inactivation. According to the\nadsorption energy parameter, we find that catechol has the highest adsorption\ndegree on titanium dioxide, followed by resorcinol, and finally hydroquinone.\nThree dihydroxybenzene isomers absorb photons belonging to ultraviolet (UV)\nrange. The lowest absorption energies of resorcinol, catechol and hydroquinone\nare respectively 3.42, 4.44 and 4.49 eV."
    },
    {
        "anchor": "Identifying the mechanism for superdiffusivity in mouse fibroblast\n  motility: We seek to characterize the motility of mouse fibroblasts on 2D substrates.\nUtilizing automated tracking techniques, we find that cell trajectories are\nsuper-diffusive, where displacements scale faster than t^(1/2) in all\ndirections. Two mechanisms have been proposed to explain such statistics in\nother cell types: run and tumble behavior with L\\'{e}vy-distributed run times,\nand ensembles of cells with heterogeneous speed and rotational noise. We\ndevelop an automated toolkit that directly compares cell trajectories to the\npredictions of each model and demonstrate that ensemble-averaged quantities\nsuch as the mean-squared displacements and velocity autocorrelation functions\nare equally well-fit by either model. However, neither model correctly captures\nthe short-timescale behavior quantified by the displacement probability\ndistribution or the turning angle distribution. We develop a hybrid model that\nincludes both run and tumble behavior and heterogeneous noise during the runs,\nwhich correctly matches the short-timescale behaviors and indicates that the\nrun times are not L\\'{e}vy distributed. The analysis tools developed here\nshould be broadly useful for distinguishing between mechanisms for\nsuperdiffusivity in other cells types and environments.",
        "positive": "Mechanisms for slow strengthening in granular materials: Several mechanisms cause a granular material to strengthen over time at low\napplied stress. The strength is determined from the maximum frictional force\nF_max experienced by a shearing plate in contact with wet or dry granular\nmaterial after the layer has been at rest for a waiting time \\tau. The layer\nstrength increases roughly logarithmically with \\tau -only- if a shear stress\nis applied during the waiting time. The mechanisms of strengthening are\ninvestigated by sensitive displacement measurements and by imaging of particle\nmotion in the shear zone. Granular matter can strengthen due to a slow shift in\nthe particle arrangement under shear stress. Humidity also leads to\nstrengthening, but is found not to be its sole cause. In addition to these time\ndependent effects, the static friction coefficient can also be increased by\ncompaction of the granular material under some circumstances, and by cycling of\nthe applied shear stress."
    },
    {
        "anchor": "Ordering and Dynamics of Vibrated Hard Squares: We study an experimental system of hard granular squares in two dimensions,\nenergized by vibration. The interplay of order in the orientations and\npositions of anisotropic particles allows for a rich set of phases. We measure\nthe structure and dynamics of steady states as a function of particle density.\nThis allows us to identify a progression of phases in which a low density\nisotropic fluid gives way to a phase with tetratic orientational order,\nshort-range translational correlations, and slowed rotational dynamics. In this\nrange of density we also observe a coupling between the molecular orientational\norder and bond-orientational order. At higher densities, the particles freeze\ninto a translationally and orientationally ordered square crystalline phase in\nwhich translational diffusion is suppressed.",
        "positive": "Self-Assembly of Patchy Colloidal Dumbbells: We employ Monte Carlo simulations to investigate the self-assembly of patchy\ncolloidal dumbbells interacting via a modified Kern-Frenkel potential by\nprobing the system concentration and dumbbell shape. We consider dumbbells\nconsisting of one attractive sphere with diameter $\\sigma_1$ and one repulsive\nsphere with diameter $\\sigma_2$ and center-to-center distance $d$ between the\nspheres. For three different size ratios, we study the self-assembled\nstructures for different separations $l = 2d/(\\sigma_1+\\sigma_2)$ between the\ntwo spheres. In particular, we focus on structures that can be assembled from\nthe homogeneous fluid, as these might be of interest in experiments. We use\ncluster order parameters to classify the shape of the formed structures. When\nthe size of the spheres is almost equal, $q=\\sigma_2/\\sigma_1=1.035$, we find\nthat, upon increasing $l$, spherical micelles are transformed to elongated\nmicelles and finally to vesicles and bilayers. For size ratio $q=1.25$ we\nobserve a continuously tunable transition from spherical to elongated micelles\nupon increasing the sphere separation. For size ratio $q=0.95$ we find bilayers\nand vesicles, plus faceted polyhedra and liquid droplets. Our results identify\nkey parameters to create colloidal vesicles with attractive dumbbells in\nexperiments."
    },
    {
        "anchor": "Injection of Deformable Capsules in a Reservoir, a Systematic Analysis: A computational study of capsule ejection from a narrow channel into a\nreservoir is undertaken for a combination of varying deformable capsule sizes\nand channel dimensions. A mass spring membrane model is coupled to an Immersed\nBoundary Lattice Boltzmann model solver. The aim of the present work is the\ndescription of the capsules motion, deformation and the response of the fluid\ndue to the complex particle dynamics. The interactions between the capsules\naffect the local velocity field significantly and are responsible for the\ndynamics observed. Capsule membrane deformability is also seen to affect inter\ncapsule interaction, and we observe that the train of three particles locally\nhomogenizes the velocity field and the leading capsule travels faster than the\nother two trailing capsules. On the contrary, variations in size of the\nreservoir do not seem to be relevant, while the ratio of capsule diameter with\nrespect to channel diameter plays a major role as well as the ratio of capsule\ndiameter to inter capsule spacing. This flow set up has not been covered in the\nliterature, and consequently we focus on describing capsule motion, membrane\ndeformation and fluid dynamics, as a preliminary investigation in this field.",
        "positive": "Pressure fluctuations in isotropic solids and fluids: Comparing isotropic solids and fluids at either imposed volume or pressure we\ninvestigate various correlations of the instantaneous pressure and its ideal\nand excess contributions. Focusing on the compression modulus K it is\nemphasized that the stress fluctuation representation of the elastic moduli may\nbe obtained directly (without a microscopic displacement field) by comparing\nthe stress fluctuations in conjugated ensembles. This is made manifest by\ncomputing the Rowlinson stress fluctuation expression K_row of the compression\nmodulus for NPT-ensembles. It is shown theoretically and numerically that\nK_row|P = P_id (2 - P_id/K) with P_id being the ideal pressure contribution."
    },
    {
        "anchor": "Phase transition in liquid crystal elastomer - a Monte Carlo study\n  employing non-Boltzmann sampling: We investigate Isotropic - Nematic transition in liquid crystal elastomers\nemploying non-Boltzmann Monte Carlo techniques. We consider a lattice model of\na liquid elastomer and Selinger-Jeon-Ratna Hamiltonian which accounts for\nhomogeneous/inhomogeneous interactions among liquid crystalline units,\ninteraction of local nematics with global strain, and with inhomogeneous\nexternal fields and stress. We find that when the local director is coupled\nstrongly to the global strain the transition is strongly first order; the\ntransition softens when the coupling becomes weaker. Also the transition\ntemperature decreases with decrease of coupling strength. Besides we find that\nthe nematic order scales nonlinearly with global strain especially for strong\ncoupling and at low temperatures.",
        "positive": "Affine and non-affine motions in sheared polydisperse jammed emulsions: We study dense and highly polydisperse emulsions at droplet volume fractions\n\\phi >= 0.65. We apply oscillatory shear and observe droplet motion using\nconfocal microscopy. The presence of droplets with sizes several times the mean\nsize dramatically changes the motion of smaller droplets. Both affine and\nnonaffine droplet motions are observed, with the more nonaffine motion\nexhibited by the smaller droplets which are pushed around by the larger\ndroplets. Droplet motions are correlated over length scales from one to four\ntimes the mean droplet diameter, with larger length scales corresponding to\nhigher strain amplitudes (up to strains of about 6%)."
    },
    {
        "anchor": "Weak non-linear surface charging effects in electrolytic films: A simple model of soap films with nonionic surfactants stabilized by added\nelectrolyte is studied. The model exhibits charge regularization due to the\nincorporation of a physical mechanism responsible for the formation of a\nsurface charge. We use a Gaussian field theory in the film but the full\nnon-linear surface terms which are then treated at a one-loop level by\ncalculating the mean-field Poisson-Boltzmann solution and then the fluctuations\nabout this solution. We carefully analyze the renormalization of the theory and\napply it to a triple layer model for a thin film with Stern layer of thickness\n$h$. For this model we give expressions for the surface charge $\\sigma(L)$ and\nthe disjoining pressure $P_d(L)$ and show their dependence on the parameters.\nThe influence of image charges naturally arise in the formalism and we show\nthat predictions depend strongly on $h$ because of their effects. In\nparticular, we show that the surface charge vanishes as the film thickness $L\n\\to 0$. The fluctuation terms about this class of theories exhibit a\nCasimir-like attraction across the film and although this attraction is well\nknown to be negligible compared with the mean-field component for thick films\nin the presence of electrolyte, in the model studied here these fluctuations\nalso affect the surface charge regulation leading to a fluctuation component in\nthe disjoining pressure which has the same behavior as the mean-field component\neven for large film thickness.",
        "positive": "A microscopic theory of photonucleation: Density functional approach for\n  the properties of a fluid of two-level atoms, a part of which is excited: We use the density functional method to examine the properties of the\nnonuniform (two-phase) fluid of two-level atoms, a part of which is excited.\nBasing on the analysis of the equation of state of a gas of two-level atoms, a\npart of which is excited, we suggest a simple density functional of the grand\nthermodynamical potential. We use the proposed density functional of the grand\nthermodynamical potential to calculate the nucleation barrier for\nvapor-to-liquid phase transition in the presence of excited atoms."
    },
    {
        "anchor": "Nonaffine Correlations in Random Elastic Media: Materials characterized by spatially homogeneous elastic moduli undergo\naffine distortions when subjected to external stress at their boundaries, i.e.,\ntheir displacements $\\uv (\\xv)$ from a uniform reference state grow linearly\nwith position $\\xv$, and their strains are spatially constant. Many materials,\nincluding all macroscopically isotropic amorphous ones, have elastic moduli\nthat vary randomly with position, and they necessarily undergo nonaffine\ndistortions in response to external stress. We study general aspects of\nnonaffine response and correlation using analytic calculations and numerical\nsimulations. We define nonaffine displacements $\\uv' (\\xv)$ as the difference\nbetween $\\uv (\\xv)$ and affine displacements, and we investigate the\nnonaffinity correlation function $\\mathcal{G} = < [\\uv'(\\xv) - \\uv' (0)]^2>$\nand related functions. We introduce four model random systems with random\nelastic moduli induced by locally random spring constants, by random\ncoordination number, by random stress, or by any combination of these. We show\nanalytically and numerically that $\\mathcal{G}$ scales as $A |\\xv|^{-(d-2)}$\nwhere the amplitude $A$ is proportional to the variance of local elastic moduli\nregardless of the origin of their randomness. We show that the driving force\nfor nonaffine displacements is a spatial derivative of the random elastic\nconstant tensor times the constant affine strain. Random stress by itself does\nnot drive nonaffine response, though the randomness in elastic moduli it may\ngenerate does. We study models with both short and long-range correlations in\nrandom elastic moduli.",
        "positive": "Inhomogeneous shear flows in soft jammed materials with tunable\n  attractive forces: We perform molecular dynamics simulations to characterize the occurrence of\ninhomogeneous shear flows in soft jammed materials. We use rough walls to\nimpose a simple shear flow and study the athermal motion of jammed assemblies\nof soft particles, both for purely repulsive interactions and in the presence\nof an additional short-range attraction of varying strength. In steady state,\npronounced flow inhomogeneities emerge for all systems when the shear rate\nbecomes small. Deviations from linear flow are stronger in magnitude and become\nvery long-lived when the strength of the attraction increases, but differ from\npermanent shear-bands. Flow inhomogeneities occur in a stress window bounded by\nthe dynamic and static yield stress values. Attractive forces enhance the flow\nheterogeneities because they accelerate stress relaxation, thus effectively\nmoving the system closer to the yield stress regime where inhomogeneities are\nmost pronounced. The present scenario for understanding the effect of particle\nadhesion on shear localization, which is based on detailed molecular dynamics\nsimulations with realistic particle interactions, differs qualitatively from\nprevious qualitative explanations and ad-hoc theoretical modelling."
    },
    {
        "anchor": "General solutions of poroelastic equations with viscous stress: Mechanical properties of cellular structures, including the cell\ncytoskeleton, are increasingly used as biomarkers for disease diagnosis and\nfundamental studies in cell biology. Recent experiments suggest that the cell\ncytoskeleton and its permeating cytosol, can be described as a poroelastic (PE)\nmaterial. Biot theory is the standard model used to describe PE materials. Yet,\nthis theory does not account for the fluid viscous stress, which can lead to\ninaccurate predictions of the mechanics in the dilute filamentous network of\nthe cytoskeleton. Here, we adopt a two-phase model that extends Biot theory by\nincluding the fluid viscous stresses in the fluid's momentum equation. We use\ngeneralized linear viscoelastic (VE) constitutive equations to describe the\npermeating fluid and the network stresses and assume a constant friction\ncoefficient that couples the fluid and network displacement fields. As the\nfirst step in developing a computational framework for solving the resulting\nequations, we derive closed-form general solutions of the fluid and network\ndisplacement fields in spherical coordinates. To demonstrate the applicability\nof our results, we study the motion of a rigid sphere moving under a constant\nforce inside a PE medium, composed of a linear elastic network and a Newtonian\nfluid. We find that the network compressibility introduces a slow relaxation of\nthe sphere and a non-monotonic network displacements with time along the\ndirection of the applied force. These novel features cannot be predicted if VE\nconstitutive equation is used for the medium. We show that our results can be\napplied to particle-tracking microrheology to differentiate between PE and VE\nmaterials and to independently measure the permeability and VE properties of\nthe fluid and the network phases.",
        "positive": "Elastic energy and string configurations in the chiral gauge theory of\n  biaxial uniaxial nematic phase transitions: In nematic liquid crystals (NLCs), topological defects of a chiral origin\nplay a role in phase transitions and lead to phase configurations of nontrivial\ntopology, like those in neutron stars and helium in the A-phase. In the\nbiaxial-uniaxial phase transition, the deformation of the orbit, as the order\nparameter degeneracy of the NLC, connects together an evolution of topological\ndefects, the surface anchoring energy and elastic Frank modui. In this work we\nestimate the chiral gauge field presentation of the constrained Ladnau-de\nGennes theory of the biaxial nematics, which have to explain their\ntopologically dependent phase transformation, using the description of the\ntransformation of disclinations in the biaxial nematic phase into the surface\nbojooms of a uniaxial NLC."
    },
    {
        "anchor": "Avalanches, Plasticity, and Ordering in Colloidal Crystals Under\n  Compression: Using numerical simulations we examine colloids with a long-range Coulomb\ninteraction confined in a two-dimensional trough potential undergoing dynamical\ncompression. As the depth of the confining well is increased, the colloids move\nvia elastic distortions interspersed with intermittent bursts or avalanches of\nplastic motion. In these avalanches, the colloids rearrange to minimize their\ncolloid-colloid repulsive interaction energy by adopting an average lattice\nconstant that is isotropic despite the anisotropic nature of the compression.\nThe avalanches take the form of shear banding events that decrease or increase\nthe structural order of the system. At larger compressions, the avalanches are\nassociated with a reduction of the number of rows of colloids that fit within\nthe confining potential, and between avalanches the colloids can exhibit\npartially crystalline or even smectic ordering. The colloid velocity\ndistributions during the avalanches have a non-Gaussian form with power law\ntails and exponents that are consistent with those found for the velocity\ndistributions of gliding dislocations. We observe similar behavior when we\nsubsequently decompress the system, and find a partially hysteretic response\nreflecting the irreversibility of the plastic events.",
        "positive": "Coexistence of defect morphologies in three dimensional active nematics: We establish how active stress globally affects the morphology of\ndisclination lines of a three dimensional active nematic liquid crystal under\nchaotic flow. Thanks to a defect detection algorithm based on the local nematic\norientation, we show that activity selects a crossover length scale in between\nthe size of small defect loops and the one of long and tangled defect lines of\nfractal dimension $2$. This length scale crossover is consistent with the\nscaling of the average separation between defects as a function of activity.\nMoreover, on the basis of numerical simulation in a 3D periodic geometry, we\nshow the presence of a network of regular defect loops, contractible onto the\n$3$-torus, always coexisting with wrapping defect lines. While the length of\nregular defects scales linearly with the emerging active length scale, it\nverifies an inverse quadratic dependence for wrapping defects. The shorter the\nactive length scale, the more the defect lines wrap around the periodic\nboundaries, resulting in extremely long and buckled structures."
    },
    {
        "anchor": "Viscoelasticity of Dilute Solutions of Semiflexible Polymers: We show using Brownian dynamics simulations and theory how the shear\nrelaxation modulus G(t) of dilute solutions of relatively stiff semiflexible\npolymers differs qualitatively from that of rigid rods. For chains shorter than\ntheir persistence length, G(t) exhibits three time regimes: At very early\ntimes, when the longitudinal deformation is affine, G(t) \\sim t^{-3/4}. Over a\nbroad intermediate regime, during which the chain length relaxes, G(t) \\sim\nt^{-5/4}. At long times, $G(t) mimics that of rigid rods. A model of the\npolymer as an effectively extensible rod with a frequency dependent elastic\nmodulus B(\\omega) \\sim (i \\omega)^{3/4} quantitatively describes G(t)\nthroughout the first two regimes.",
        "positive": "Probing the stability and magnetic properties of magnetosome chains in\n  freeze-dried magnetotactic bacteria: \\textit{Magnetospirillum gryphiswaldense} biosynthesize high quality\nmagnetite nanoparticles, called magnetosomes, and arrange them into a chain\nthat behaves like a magnetic compass. Here we perform magnetometry and\npolarized small-angle neutron scattering (SANS) experiments on a powder of\nfreeze-dried and immobilized \\textit{M. gryphiswaldense}. We confirm that the\nindividual nanoparticles are single-domain particles and that an alignment of\nthe particle moments in field direction occurs exclusively by a N\\'eel-like\nrotation. Our magnetometry results of the bacteria powder indicate an absence\nof dipolar interactions between the particle chains and a dominant uniaxial\nmagnetic anisotropy. Finally, we can verify by SANS that the chain structure\nwithin the immobilized, freeze-dried bacteria is preserved also after\napplication of large magnetic fields of up to 1\\,T."
    },
    {
        "anchor": "Plateau-Rayleigh instability of a soft layer coated on a rigid cylinder: We study the Plateau-Rayleigh instability of a viscoelastic soft solid layer\ncoated on a rigid cylinder i.e., a soft fibre with a rigid core. The onset of\ninstability is examined using a linear stability analysis. We find that\nincreasing the rigid cylinder radius reduce the growth rate of the fastest\ngrowing mode. For each rigid cylinder radius, a critical elastocapillary number\nis found below which all wavelengths of disturbances are stable. The critical\nvalue for a soft fibre with a thick rigid cylindrical core can be several\norders of magnitudes larger than that for a totally soft fibre (no rigid core),\nwhich highlights the strong stabilizing effect of the rigid core on the system.\nIncreasing the relaxation timescale of the viscoelastic material also slows\ndown the growth of disturbance, but has no effect on the critical\nelastocapillary number. Interestingly, the wavelength of the fastest growing\nmode is independent of the rigid cylinder radius for the purely elastic case.",
        "positive": "On the pressure dependence of the thermodynamical scaling exponent gamma: Since its initial discovery more than fifteen years ago, the thermodynamical\nscaling of the dynamics of supercooled liquids has been used to provide many\nnew important insights in the physics of liquids, particularly on the link\nbetween dynamics and intermolecular potential. A question that has long been\ndiscussed is whether the scaling exponent gamma is a constant or it depends on\npressure. Here we offer a simple method to determine the pressure dependence of\ngamma using only the pressure dependence of the glass transition and the\nequation of state. Using this new method we find that for the six\nnon-associated liquids investigated gamma always decreases with increasing\npressure. Importantly in all cases the value of gammaremains always larger than\n4. Liquids having gamma closer to 4 at low pressure show a smaller change in\ngamma with pressure. We argue that this result has very important consequences\nfor the experimental determination of the functional form of the repulsive part\nof the potential in liquids."
    },
    {
        "anchor": "On the shape-dependent propulsion of nano- and microparticles by\n  traveling ultrasound waves: Among the many types of artificial motile nano- and microparticles that have\nbeen developed in the past, colloidal particles that exhibit propulsion when\nthey are exposed to ultrasound are particularly advantageous. Their properties,\nhowever, are still largely unexplored. For example, the dependence of the\npropulsion on the particle shape and the structure of the flow field generated\naround the particles are still unknown. In this article, we address the\npropulsion mechanism of ultrasound-propelled nano- and microparticles in more\ndetail. Based on direct computational fluid dynamics simulations and focusing\non traveling ultrasound waves, we study the effect of two important aspects of\nthe particle shape on the propulsion: rounded vs. pointed and filled vs. hollow\nshapes. We also address the flow field generated around such particles. Our\nresults reveal that pointedness leads to an increase of the propulsion speed,\nwhereas it is not significantly affected by hollowness. Furthermore, we find\nthat the flow field of ultrasound-propelled particles allows to classify them\nas pusher squirmers, which has far-reaching consequences for the understanding\nof these particles and allows us to predict that they can be used to realize\nactive materials with a tunable viscosity that can exhibit suprafluidity and\neven negative viscosities. The obtained results are helpful, e.g., for future\nexperimental work further investigating or applying ultrasound-propelled\ncolloidal particles as well as for theoretical approaches that aim at modeling\ntheir dynamics on mesoscopic scales.",
        "positive": "Condensation of helium in nanoscopic alkali wedges at zero temperature: We present a complete calculation of the structure of liquid $^4$He confined\nto a concave nanoscopic wedge, as a function of the opening angle of the walls.\nThis is achieved within a finite-range density functional formalism. The\nresults here presented, restricted to alkali metal substrates, illustrate the\nchange in meniscus shape from rather broad to narrow wedges on weak and strong\nalkali adsorbers, and relate this change to the wetting behavior of helium on\nthe corresponding planar substrate. As the wedge angle is varied, we find a\nsequence of stable states that, in the case of cesium, undergo one filling and\none emptying transition at large and small openings, respectively. A\ncomputationally unambiguous criterion to determine the contact angle of $^4$He\non cesium is also proposed."
    },
    {
        "anchor": "Dilute gel networks vs. clumpy gels in colloid-polymer mixtures: Using Brownian dynamics simulations we study gel-forming colloid-polymer\nmixtures. The focus of this article lies on the differences of dense and dilute\ngel networks in terms of structure formation both on a local and a global\nlevel. We apply reduction algorithms and observe that dilute networks and dense\ngels differ in the way structural properties like the thickness of strands\nemerge. We also analyze the percolation behavior and find that two different\nregimes of percolation exist which might be responsible for structural\ndifferences. In dilute networks we confirm that solidity is mainly a\nconsequence of pentagonal bipyramids forming in the network. In dense gels also\ntetrahedral structures influence solidity.",
        "positive": "Critical Thickness Ratio for Buckled and Wrinkled Fruits and Vegetables: Fruits and vegetables are usually composed of exocarp and sarcocarp and they\ntake a variety of shapes when they are ripe. Buckled and wrinkled fruits and\nvegetables are often observed. This work aims at establishing the geometrical\nconstraint for buckled and wrinkled shapes based on a mechanical model. The\nmismatch of expansion rate between the exocarp and sarcocarp can produce a\ncompressive stress on the exocarp. We model a fruit/vegetable with exocarp and\nsarcocarp as a hyperelastic layer-substrate structure subjected to uniaxial\ncompression. The derived bifurcation condition contains both geometrical and\nmaterial constants. However, a careful analysis on this condition leads to the\nfinding of a critical thickness ratio which separates the buckling and\nwrinkling modes, and remarkably, which is independent of the material\nstiffnesses. More specifically, it is found that if the thickness ratio is\nsmaller than this critical value a fruit/vegetable should be in a buckling mode\n(under a sufficient stress); if a fruit/vegetable in a wrinkled shape the\nthickness ratio is always larger than this critical value. To verify the\ntheoretical prediction, we consider four types of buckled fruits/vegetables and\nfour types of wrinkled fruits/vegetables with three samples in each type. The\ngeometrical parameters for the 24 samples are measured and it is found that\nindeed all the data fall into the theoretically predicted buckling or wrinkling\ndomains. Some practical applications based on this critical thickness ratio are\nbriefly discussed."
    },
    {
        "anchor": "Role of a polymeric component in the phase separation of ternary fluid\n  mixtures: A dissipative particle dynamics study: We present the results from dissipative particle dynamics (DPD) simulations\nof phase separation dynamics in ternary (ABC) fluids mixture in $d=3$ where\ncomponents A and B represent the simple fluids and component C represents a\npolymeric fluid. Here, we study the role of polymeric fluid (C) on domain\nmorphology by varying composition ratio, polymer chain length, and polymer\nstiffness. We observe that the system under consideration lies in the same\ndynamical universality class as a simple ternary fluids mixture. However, the\nscaling functions depend upon the parameters mentioned above as they change the\ntime scale of the evolution morphologies. In all cases, the characteristic\ndomain size follows: $l(t) \\sim t^{\\phi} $ with dynamic growth exponent $\\phi$,\nshowing a crossover from the viscous hydrodynamic regime $(\\phi=1)$ to the\ninertial hydrodynamic regime $(\\phi=2/3)$ in the system at late times.",
        "positive": "Compressing $\u0398$-chain in slit geometry: When compressed in a slit of width $D$, a $\\Theta$-chain that displays the\nscaling of size $R_0$ (diameter) with respect to the number of monomers $N$,\n$R_0\\sim aN^{1/2}$, expands in the lateral direction as $R_{\\parallel}\\sim a\nN^{\\nu}(a/D)^{2\\nu-1}$. Provided that the $\\Theta$ condition is strictly\nmaintained throughout the compression, the well-known scaling exponent of\n$\\Theta$-chain in 2 dimensions, $\\nu=4/7$, is anticipated in a perfect\nconfinement. However, numerics shows that upon increasing compression from\n$R_0/D<1$ to $R_0/D\\gg 1$, $\\nu$ gradually deviates from $\\nu=1/2$ and plateaus\nat $\\nu=3/4$, the exponent associated with the self-avoiding walk in two\ndimensions. Using both theoretical considerations and numerics, we argue that\nit is highly nontrivial to maintain the $\\Theta$ condition under confinement\nbecause of two major effects. First, as the dimension is reduced from 3 to 2\ndimensions, the contributions of higher order virial terms, which can be\nignored in 3 dimensions at large $N$, become significant. Second and more\nimportantly, the geometrical confinement, which is regarded as an applied\nexternal field, alters the second virial coefficient ($B_2$) changes from\n$B_2=0$ ($\\Theta$ condition) in free space to $B_2>0$ (good-solvent condition)\nin confinement. Our study provides practical insight into how confinement\naffects the conformation of a single polymer chain."
    },
    {
        "anchor": "Application of M\u00f6ssbauer spectroscopy to study vibrations of a\n  granular medium excited by ultrasound: It is shown that analysis of M\\\"{o}ssbaur spectra of a granulated medium,\nimmersed into the epoxy resin without hardener, allows to study mechanical\nvibrations of granules. In our experiments, small particles of the potassium\nferrocyanide with a 1.25 micron mean size played a role of granules. This\ncompound was enriched by $^{57}$Fe isotope. Particle vibrations in the vibrated\nresin with the frequency 12.72 MHz were induced by piezo polymer film. At rest,\nM\\\"{o}ssbauer spectrum of $^{57}$Fe in the potassium ferrocyanide consists of a\nsingle line. Ultrasonic vibration of nuclei splits the line into a comb\nstructure with a period equal to the vibration frequency. The spectrum analysis\nallows to estimate the vibration amplitude of particles and decay of the\nultrasound in this medium. The proposed method is unique since it allows to\nmeasure subangstrom displacements of particles vibrating with several MHz\nfrequency.",
        "positive": "Relaxation oscillations of Zeeman and dipole magnetizations of a\n  paramagnet under conditions of deep low-frequency modulation: The relaxation oscillations of Zeeman and dipole magnetizaions in spin system\nof a solid paramagnet are theoretically analyzed under conditions of\nintermediate saturation of magnetic resonance and strong low-frequency\nmodulation of the external magnetic field. Peculiarities of the relaxation\noscillations in the synchronous detection regime are considered."
    },
    {
        "anchor": "Overcharging, charge inversion and reentrant condensation: Using\n  highly-charged polyelectrolytes in tetravalent salt solutions as an example\n  of study: We study salt-induced charge overcompensation and charge inversion of\nflexible polyelectrolytes via computer simulations and demonstrate the\nimportance of ion excluded volume. Reentrant condensation takes place when the\nion size is comparable to monomer size, and happens in a middle region of salt\nconcentration. In a high-salt region, ions can overcharge a chain near its\nsurface and charge distribution around a chain displays an oscillatory\nbehavior. Unambiguous evidence obtained by electrophoresis shows that charge\ninversion does not necessarily appear with overcharging and occurs when the ion\nsize is not big. These findings suggest a disconnection of resolubilization of\npolyelectrolyte condensates at high salt concentration with charge inversion.",
        "positive": "Nonphononic spectrum of two-dimensional structural glasses: The scaling form and system-size dependence of the low-frequency wing of the\nnonphononic vibrational spectrum of two-dimensional structural glasses have\nbeen debated in recent literature. Here we provide numerical evidence that the\nprefactor $A_{\\rm g}$ of the low-frequency nonphononic vibrational spectrum --\nthe latter grows from zero frequency ($\\omega\\!=\\!0$) as $A_{\\rm\ng}\\omega^\\beta$ -- is system-size dependent, and that the exponent $\\beta$\nexhibits a similar glass-formation-protocol and system-size dependence as seen\nin three-dimensional structural glasses."
    },
    {
        "anchor": "Dynamics of microstructure anisotropy and rheology of soft jammed\n  suspensions: We explore the rheology predicted by a recently proposed constitutive model\nfor jammed suspensions of soft elastic particles derived from particle-level\ndynamics [Cuny et al., Phys. Rev. Lett. 127, 218003 (2021)]. Our model predicts\nthat the orientation of the anisotropy of the microstructure, governed by an\ninterplay between advection and contact elasticity, plays a key role at\nyielding and in flow. It generates normal stress differences contributing\nsignificantly to the yield criterion and Trouton ratio. It gives rise to\nnon-trivial transients such as stress overshoots in step increases of shear\nrate, residual stresses after flow cessation and power-law decay of the shear\nrate in creep. Finally, it explains the collapse of storage modulus as measured\nin parallel superposition for a yielded suspension.",
        "positive": "Revisiting the Persson theory of elastoplastic contact: A simpler\n  closed-form solution and a rigorous proof of boundary conditions: Persson's theory of contact is extensively used in the study of the purely\nnormal interaction between a nominally flat rough surface and a rigid flat. In\nthe literature, Persson's theory was successfully applied to the elastoplastic\ncontact problem with a scale-independent hardness $H$. However, it yields a\nclosed-form solution, $P(p, \\xi)$, in terms of an infinite sum of sines. In\nthis study, $P(p, \\xi)$ is found to have a simpler form which is a\nsuperposition of three Gaussian functions. A rigorous proof of the boundary\ncondition $P(p=0, \\xi)=P(p=H, \\xi) = 0$ is given based on the new solution."
    },
    {
        "anchor": "The Origin of the Designability of Protein Structures: We examined what determines the designability of 2-letter codes (H and P)\nlattice proteins from three points of view. First, whether the native structure\nis searched within all possible structures or within maximally compact\nstructures. Second, whether the structure of the used lattice is bipartite or\nnot. Third, the effect of the length of the chain, namely, the number of\nmonomers on the chain. We found that the bipartiteness of the lattice structure\nis not a main factor which determines the designability. Our results suggest\nthat highly designable structures will be found when the length of the chain is\nsufficiently long to make the hydrophobic core consisting of enough number of\nmonomers.",
        "positive": "Geometric friction directs cell migration: In the absence of environmental cues, a migrating cell performs an isotropic\nrandom motion. Recently, the breaking of this isotropy has been observed when\ncells move in the presence of asymmetric adhesive patterns. However, up to now\nthe mechanisms at work to direct cell migration in such environments remain\nunknown. Here, we show that a non-adhesive surface with asymmetric\nmicro-geometry consisting of dense arrays of tilted micro-pillars can direct\ncell motion. Our analysis reveals that most features of cell trajectories,\nincluding the bias, can be reproduced by a simple model of active Brownian\nparticle in a ratchet potential, which we suggest originates from a generic\nelastic interaction of the cell body with the environment. The observed guiding\neffect, independent of adhesion, is therefore robust and could be used to\ndirect cell migration both in vitro and in vivo."
    },
    {
        "anchor": "Out-of-equilibrium interactions and collective locomotion of colloidal\n  spheres with squirming of nematoelastic multipoles: Many living and artificial systems show a similar emergent behavior and\ncollective motions on different scales, starting from swarms of bacteria to\nsynthetic active particles, herds of mammals and crowds of people. What all\nthese systems often have in common is that new collective properties like\nflocking emerge from interactions between individual self-propelled or\nexternally driven units. Such systems are naturally out-of-equilibrium and\npropel at the expense of consumed energy. Mimicking nature by making\nself-propelled or externally driven particles and studying their individual and\ncollective motility may allow for deeper understanding of physical\nunderpinnings behind the collective motion of large groups of interacting\nobjects or beings. Here, using a soft matter system of colloids immersed into a\nliquid crystal, we show that resulting so-called nematoelastic multipoles can\nbe set into a bidirectional locomotion by external periodically oscillating\nelectric fields. Out-of-equilibrium elastic interactions between such colloids\nlead to collective flock-like behaviors, which emerge from time-varying\nelasticity-mediated interactions between externally driven propelling\nparticles. The repulsive elastic interactions in the equilibrium state can be\nturned into attractive interactions in the out-of-equilibrium state under\napplied electric fields. We probe this behavior at different number densities\nof colloidal particles and show that particles in a dense dispersion\ncollectively select the same direction of a coherent motion due to elastic\ninteractions between near neighbors. In our experimentally implemented design,\ntheir motion is highly ordered and without clustering or jamming often present\nin other colloidal transport systems, which is promising for technological and\nfundamental-science applications, like nano-cargo transport, out-of-equilibrium\nassembly and microrobotics.",
        "positive": "Dynamics of magnetoelastic robots in water-saturated granular beds: We investigate the dynamics of a magnetoelastic robot with a dipolar magnetic\nhead and a slender elastic body as it performs undulatory strokes and burrows\nthrough water-saturated granular beds. The robot is actuated by an oscillating\nmagnetic field and moves forward when the stroke amplitude increases above a\ncritical threshold. By visualizing the medium, we show that the undulating body\nfluidizes the bed, resulting in the appearance of a dynamic burrow, which\nrapidly closes in behind the moving robot as the medium loses energy. We\ninvestigate the applicability of Lighthill's elongated body theory of fish\nlocomotion, and estimate the contribution of thrust generated by the undulating\nbody and the drag incorporating the granular volume fraction-dependent\neffective viscosity of the medium. The projected speeds are found to be\nconsistent with the measured speeds over a range of frequencies and amplitudes\nabove the onset of forward motion. However, systematic deviations are found to\ngrow with increasing driving, pointing to a need for further sophisticated\nmodelling of the medium-structure interactions."
    },
    {
        "anchor": "On the existence of elastic minimizers for initially stressed materials: A soft solid is said to be initially stressed if it is subjected to a state\nof internal stress in its unloaded reference configuration. Developing a sound\nmathematical framework to model initially stressed solids in nonlinear\nelasticity is key for many applications in engineering and biology. This work\ninvestigates the links between the existence of elastic minimizers and the\nconstitutive restrictions for initially stressed materials subjected to finite\ndeformations. In particular, we consider a subclass of constitutive responses\nin which the strain energy density is taken as a scalar valued function of both\nthe deformation gradient and the initial stress tensor. The main advantage of\nthis approach is that the initial stress tensor belongs to the group of the\ndivergence-free symmetric tensors satisfying the boundary condition in any\ngiven reference configuration. However, it is still unclear which physical\nrestrictions must be imposed for the well-posedness of this elastic problem.\nAssuming that the constitutive response depends on the choice of the reference\nconfiguration only through the initial stress tensor, under given conditions we\nprove the local existence of a relaxed state given by an implicit tensor\nfunction of the initial stress distribution. This tensor function is generally\nnot unique, and can be transformed accordingly to the symmetry group of the\nmaterial at fixed initial stresses. These results allow to extend Ball's\nexistence theorem of elastic minimizers for the proposed constitutive choice of\ninitially stressed materials.",
        "positive": "The distinguishable-particle lattice model of glasses in three\n  dimensions: The nature of glassy states in realistic finite dimensions is still under\nfierce debate. Lattice models can offer valuable insights and facilitate deeper\ntheoretical understanding. Recently, a disordered-interacting lattice model\nwith distinguishable particles in two dimensions (2D) has been shown to produce\na wide range of dynamical properties of structural glasses, including the slow\nand heterogeneous characteristics of the glassy dynamics, various fragility\nbehaviors of glasses, and so on. These findings support the usefulness of this\nmodel for modeling structural glasses. An important question is whether such\nproperties still hold in the more realistic three dimensions. In this study, we\naim to extend the distinguishable-particle lattice model (DPLM) to three\ndimensions (3D) and explore the corresponding glassy dynamics. Through\nextensive kinetic Monte Carlo simulations, we found that the 3D DPLM exhibits\nmany typical glassy behaviors, such as plateaus in the mean square displacement\nof particles and the self-intermediate scattering function, dynamic\nheterogeneity, variability of glass fragilities, and so on, validating the\neffectiveness of the DPLM in a broader realistic setting. The observed glassy\nbehaviors of the 3D DPLM appear similar to those of its 2D counterpart, in\naccordance with recent findings in molecular models of glasses. We further\ninvestigate the role of void-induced motions in dynamical relaxations and\ndiscuss their relation to dynamic facilitation. As lattice models tend to keep\nthe minimal but important modeling elements, they are typically much more\namenable to analysis. Therefore, we envisage that the DPLM will benefit future\ntheoretical developments, such as the configuration tree theory, towards a more\ncomprehensive understanding of structural glasses."
    },
    {
        "anchor": "Theory of the Spatial Transfer of Interface-Nucleated Changes of\n  Dynamical Constraints and Its Consequences in Glass-Forming Films: We formulate a new theory for how caging constraints in glass-forming liquids\nat a surface or interface are modified and then spatially transferred, in a\nlayer-by-layer bootstrapped manner, into the film interior in the context of\nthe dynamic free energy concept of the Nonlinear Langevin Equation theory\napproach. The dynamic free energy at any mean location involves contributions\nfrom two adjacent layers where confining forces are not the same. At the most\nfundamental level of the theory, the caging component of the dynamic free\nenergy varies essentially exponentially with distance from the interface,\nsaturating deep enough into the film with a correlation length of modest size\nand weak sensitivity to thermodynamic state. This imparts a roughly exponential\nspatial variation of all the key features of the dynamic free energy required\nto compute gradients of dynamical quantities including the localization length,\njump distance, cage barrier, collective elastic barrier and alpha relaxation\ntime. The spatial gradients are entire of dynamical, not structural nor\nthermodynamic, origin. The theory is implemented for the hard sphere fluid and\ndiverse interfaces which can be a vapor, a rough pinned particle solid, a\nvibrating pinned particle solid, or a smooth hard wall. Their basic description\nat the level of the spatially-heterogeneous dynamic free energy is identical,\nwith the crucial difference arising from the first layer where dynamical\nconstraints can be weakened, softened, or hardly changed depending on the\nspecific interface. Numerical calculations establish the spatial dependence and\nfluid volume fraction sensitivity of the key dynamical property gradients for\nfive different model interfaces. Comparison of the theoretical predictions for\nthe dynamic localization length and glassy modulus with simulations and\nexperiments for systems with a vapor interface reveals good agreement.",
        "positive": "Eddies and interface deformations induced by optical streaming: We study flows and interface deformations produced by the scattering of a\nlaser beam propagating through non-absorbing turbid fluids. Light scattering\nproduces a force density resulting from the transfer of linear momentum from\nthe laser to the scatterers. The flow induced in the direction of the beam\npropagation, called 'optical streaming', is also able to deform the interface\nseparating the two liquid phases and to produce wide humps. The viscous flow\ntaking place in these two liquid layers is solved analytically, in one of the\ntwo liquid layers with a stream function formulation, as well as numerically in\nboth fluids using a boundary integral element method. Quantitative comparisons\nare shown between the numerical and analytical flow patterns. Moreover, we\npresent predictive simulations regarding the effects of the geometry, of the\nscattering strength and of the viscosities, on both the flow pattern and the\ndeformation of the interface. Finally, theoretical arguments are put forth to\nexplain the robustness of the emergence of secondary flows in a two-layer fluid\nsystem."
    },
    {
        "anchor": "Non-continuous Froude number scaling for the closure depth of a\n  cylindrical cavity: A long, smooth cylinder is dragged through a water surface to create a cavity\nwith an initially cylindrical shape. This surface void then collapses due to\nthe hydrostatic pressure, leading to a rapid and axisymmetric pinch-off in a\nsingle point. Surprisingly, the depth at which this pinch-off takes place does\nnot follow the expected Froude$^{1/3}$ power-law. Instead, it displays two\ndistinct scaling regimes separated by discrete jumps, both in experiment and in\nnumerical simulations (employing a boundary integral code). We quantitatively\nexplain the above behavior as a capillary waves effect. These waves are created\nwhen the top of the cylinder passes the water surface. Our work thus gives\nfurther evidence for the non-universality of the void collapse.",
        "positive": "Density functional theory for soft matter with mesoscopic length scale\n  fluctuations included within field-theoretic formalism: Mesoscopic theory for soft-matter systems that combines density functional\nand statistical field theory is derived from the microscopic theory by a\nsystematic coarse-graining procedure. Within the framework of this theory we\nobtain the universal sequence of phases: disordered, bcc, hexagonal, lamellar,\ninverted hexagonal, inverted bcc, disordered, for increasing density well below\nthe close-packing density. In addition to the above phases, more complex phases\nmay appear depending on the interaction potentials. For a particular form of\nthe short-range attraction long-range repulsion potential we find the\nbicontinuous gyroid phase (Ia3d symmetry) that may be related to a network\nforming cluster of colloids in a mixture of colloids and nonadsorbing polymers."
    },
    {
        "anchor": "The role of long-range forces in the phase behavior of colloids and\n  proteins: The phase behavior of colloid-polymer mixtures, and of solutions of globular\nproteins, is often interpreted in terms of a simple model of hard spheres with\nshort-ranged attraction. While such a model yields a qualitative understanding\nof the generic phase diagrams of both colloids and proteins, it fails to\ncapture one important difference: the model predicts fluid-fluid phase\nseparation in the metastable regime below the freezing curve. Such demixing has\nbeen observed for globular proteins, but for colloids it appears to be\npre-empted by the appearance of a gel. In this paper, we study the effect of\nadditional long-range attractions on the phase behavior of spheres with\nshort-ranged attraction. We find that such attractions can shift the\n(metastable) fluid-fluid critical point out of the gel region. As this\nmetastable critical point may be important for crystal nucleation, our results\nsuggest that long-ranged attractive forces may play an important role in the\ncrystallization of globular proteins. However, in colloids, where refractive\nindex matching is often used to switch off long-ranged dispersion forces,\ngelation is likely to inhibit phase separation.",
        "positive": "A molecular equation of state for alcohols which includes steric\n  hindrance in hydrogen bonding: In this paper we develop the first equation of state for alcohol containing\nmixtures which includes the effect of steric hindrance between the two electron\nlone pair hydrogen bond acceptor sites on the alcohol's hydroxyl oxygen. The\ntheory is derived for multi-component mixtures within Wertheim's multi-density\nstatistical mechanics in a second order perturbation theory. The accuracy of\nthe new approach is demonstrated by application to pure methanol and ethanol\nand binary ethanol / water mixtures. It is demonstrated that the new approach\ngives a substantial improvement in the prediction of hydrogen bond structure of\nboth pure alcohol and alcohol / water mixtures as compared to standard first\norder approaches."
    },
    {
        "anchor": "Three-Dimensional Multicomponent Vesicles: Dynamics & Influence of\n  Material Properties: In this work, the nonlinear dynamics of a fully three-dimensional\nmulticomponent vesicle in shear flow are explored. Using a volume- and\narea-conserving projection method coupled to a gradient-augmented level set and\nsurface phase method, the dynamics are systematically studied as a function of\nthe membrane bending rigidity difference between the components, the speed of\ndiffusion compared to the underlying shear flow, and the strength of the phase\ndomain energy compared to the bending energy. Using a pre-segregated vesicle,\nthree dynamics are observed: stationary phase, phase-treading, and a new\ndynamic called vertical banding. These regimes are very sensitive to the\nstrength of the domain line energy, as the vertical banding regime is not\nobserved when line energy is larger than the bending energy. These findings\ndemonstrate that a complete understanding of multicomponent vesicle dynamics\nrequire that the full three-dimensional system be modeled, and show the\ncomplexity obtained when considering heterogeneous material properties.",
        "positive": "Intermittent gravity-driven flow of grains through narrow pipes: Grain flows through pipes are frequently found in various settings, such as\nin pharmaceutical, chemical, petroleum, mining and food industries. In the case\nof size-constrained gravitational flows, density waves consisting of\nalternating high- and low-compactness regions may appear. This study\ninvestigates experimentally the dynamics of density waves that appear in\ngravitational flows of fine grains through vertical and slightly inclined\npipes. The experimental device consisted of a transparent glass pipe through\nwhich different populations of glass spheres flowed driven by gravity. Our\nexperiments were performed under controlled ambient temperature and relative\nhumidity, and the granular flow was filmed with a high-speed camera.\nExperimental results concerning the length scales and celerities of density\nwaves are presented, together with a one-dimensional model and a linear\nstability analysis. The analysis exhibits the presence of a long-wavelength\ninstability, with the most unstable mode and a cut-off wavenumber whose values\nare in agreement with the experimental results."
    },
    {
        "anchor": "Some New Aspects of Dendrimer Applications: Dendrimers are characterized by special features that make them promising\ncandidates for many applications. Here we focus on two such applications:\ndendrimers as light harvesting antennae, and dendrimers as molecular\namplifiers, which may serve as novel platforms for drug delivery. Both\napplications stem from the unique structure of dendrimers. We present a\ntheoretical framework based on the master equation within which we describe\nthese applications. The quantities of interest are the first passage time (FPT)\nprobability density function (PDF), and its moments. We examine how the FPT PDF\nand its characteristics depend on the geometric and energetic structures of the\ndendrimeric system. In particular, we investigate the dependence of the FPT\nproperties on the number of generations (dendrimer size), and the system bias.\nWe present analytical expressions for the FPT PDF for very efficient\ndendrimeric antennae and for dendrimeric amplifiers. For these cases the mean\nfirst passage time scales linearly with the system length, and fluctuations\naround the mean first passage time are negligible for large systems.\nRelationships of the FPT to light harvesting process for other types of\nsystem-bias are discussed.",
        "positive": "Possible influence of the Kuramoto length in a photo-catalytic water\n  splitting reaction revealed by Poisson--Nernst--Planck equations involving\n  ionization in a weak electrolyte: We studied ion concentration profiles and the charge density gradient caused\nby electrode reactions in weak electrolytes by using the\nPoisson--Nernst--Planck equations without assuming charge neutrality. In weak\nelectrolytes, only a small fraction of molecules is ionized in bulk. Ion\nconcentration profiles depend on not only ion transport but also the ionization\nof molecules. We considered the ionization of molecules and ion association in\nweak electrolytes and obtained analytical expressions for ion densities,\nelectrostatic potential profiles, and ion currents. We found the case that the\ntotal ion density gradient was given by the Kuramoto length which characterized\nthe distance over which an ion diffuses before association. The charge density\ngradient is characterized by the Debye length for 1:1 weak electrolytes. We\ndiscuss the role of these length scales for efficient water splitting reactions\nusing photo-electrocatalytic electrodes."
    },
    {
        "anchor": "An Ising-Like model for protein mechanical unfolding: The mechanical unfolding of proteins is investigated by extending the\nWako-Saito-Munoz-Eaton model, a simplified protein model with binary degrees of\nfreedom, which has proved successful in describing the kinetics of protein\nfolding. Such a model is generalized by including the effect of an external\nforce, and its thermodynamics turns out to be exactly solvable. We consider two\nmolecules, the 27th immunoglobulin domain of titin and protein PIN1. In the\ncase of titin we determine equilibrium force-extension curves and study\nnonequilibrium phenomena in the frameworks of dynamic loading and force clamp\nprotocols, verifying theoretical laws and finding the position of the kinetic\nbarrier which hinders the unfolding of the molecule. The PIN1 molecule is used\nto check the possibility of computing the free energy landscape as a function\nof the molecule length by means of an extended form of the Jarzynski equality.",
        "positive": "Actin polymerization front propagation in a comb-reaction system: Anomalous transport and reaction dynamics are considered by providing the\ntheoretical grounds for the possible experimental realization of actin\npolymerization in comb-like geometry. Two limiting regimes are recovered,\ndepending on the concentration of reagents (magnesium and actin). These are\nboth the failure of the reaction front propagation and a finite speed\ncorresponding to the Fisher-KPP long time asymptotic regime."
    },
    {
        "anchor": "Wrinkles in the opening angle method: We investigate the stability of the deformation modeled by the opening angle\nmethod, often used to give a measure of residual stresses in arteries and other\nbiological soft tubular structures. Specifically, we study the influence of\nstiffness contrast, dimensions and inner pressure on the onset of wrinkles when\nan open sector of a soft tube, coated with a stiffer film, is bent into a full\ncylinder. The tube and its coating are made of isotropic, incompressible,\nhyperelastic materials. We provide a full analytical exposition of the\ngoverning equations and the associated boundary value problem for the large\ndeformation and for the superimposed small-amplitude wrinkles. For\nillustration, we solve them numerically with a robust algorithm in the case of\nMooney-Rivlin materials. We confront the results to experimental data that we\ncollected for soft silicone sectors. We study the influence of axial stretch\nand inner pressure on the stability of closed-up coated tubes with material\nparameters comparable with those of soft biological tubes such as arteries and\nveins, although we do not account for anisotropy. We find that the large\ndeformation described in the opening angle method does not always exist, as it\ncan become unstable for certain combinations of dimensions and material\nparameters.",
        "positive": "Internal and interfacial friction in the dynamics of soft/solid\n  interfaces: We analyze theoretically the effect of friction on quartz crystal\nmicrobalance (QCM) measurements that probe soft (viscoelastic) films and\nbiomolecular layers adsorbed from aqueous solutions. While water provides a\nnatural environment for biomolecules, an interface with unknown rheological\nproperties forms between the adsorbed soft molecular layer and the quartz\nsubstrate in the latter case. We investigate therefore the dynamics of soft\nfilms adsorbed onto a solid quartz surface within a continuum mechanics\napproach using both the Maxwell and the Voight/Kelvin models of viscoelasticity\nand their combination. The rigorous expressions derived for the acoustic\nresponse of a quartz crystal oscillator, accounting for both interfacial\n(sliding) friction and internal friction (viscosity), demonstrate that the QCM\ncan be used as a sensor for quantitative characteristization of friction\neffects as well as for ``in situ'' measurements of mechanical properties of\nadsorbed biomolecular films."
    },
    {
        "anchor": "Cavitation-induced force transition in confined viscous liquids under\n  traction: We perform traction experiments on simple liquids highly confined between\nparallel plates. At small separation rates, we observe a simple response\ncorresponding to a convergent Poiseuille flow. Dramatic changes in the force\nresponse occur at high separation rates, with the appearance of a force plateau\nfollowed by an abrupt drop. By direct observation in the course of the\nexperiment, we show that cavitation accounts for these features which are\nreminiscent of the utmost complex behavior of adhesive films under traction.\nSurprisingly enough, this is observed here in purely viscous fluids.",
        "positive": "Anomalous fluctuations in homogeneous fluid phase of active Brownian\n  particles: Giant number fluctuations (GNF) are an anomaly universally observed in active\nfluids with polar or nematic order. In this paper, we show that GNF arise in\nthe fluid phase of active Brownian particles (ABP), where the polar order is\nabsent. GNF in ABP extends over a large but finite length which characterizes\nthe growing velocity correlations. To suppress unwanted phase separation and\nallow ones to explore the disordered fluid phase at large activities, we impart\nthe inertia, or the mass, to the ABP. A linearized hydrodynamic theory captures\nour findings, but only qualitatively. We find numerically a nontrivial scaling\nrelation for the density correlation function, which the linearized theory\ncannot explain. The results suggest ubiquitousness of the anomalous\nfluctuations even in the disordered homogeneous fluid phase in the absence of\nthe directional order."
    },
    {
        "anchor": "Understanding rheological hysteresis in soft glassy materials: Motivated by recent experimental studies of rheological hysteresis in soft\nglassy materials, we study numerically strain rate sweeps in simple yield\nstress fluids and viscosity bifurcating yield stress fluids. Our simulations of\ndownward followed by upward strain rate sweeps, performed within fluidity\nmodels and the soft glassy rheology model, successfully capture the\nexperimentally observed monotonic decrease of the area of the rheological\nhysteresis loop with sweep time in simple yield stress fluids, and the bell\nshaped dependence of hysteresis loop area on sweep time in viscosity\nbifurcating fluids. We provide arguments explaining these two different\nfunctional forms in terms of differing tendencies of simple and viscosity\nbifurcating fluids to form shear bands during the sweeps, and show that the\nbanding behaviour captured by our simulations indeed agrees with that reported\nexperimentally. We also discuss the difference in hysteresis behaviour between\ninelastic and viscoelastic fluids. Our simulations qualitatively agree with the\nexperimental data discussed here for four different soft glassy materials.",
        "positive": "Nearly hyperuniform, nonhyperuniform, and antihyperuniform density\n  fluctuations in two-dimensional transition metal dichalcogenides with defects: Hyperuniform many-body systems in $d$-dimensional Euclidean space are\ncharacterized by completely suppressed (normalized) infinite-wavelength density\nfluctuations, and appear to be endowed with novel exotic physical properties.\nIn this work, we analyze the effects of localized defects on the density\nfluctuations across length scales and on the hyperuniformity property of\nexperimental samples of two-dimensional transition metal dichalcogenides. In\nparticular, we extract atomic coordinates from time series annular dark\nfield-scanning transmission electron microscopy imaging data of 2D tungsten\nchalcogenides with the 2H structure showing continuous development and\nevolution of electron-beam induced defects, and construct the corresponding\nchemical-bonding informed coordination networks between the atoms. We then\ncompute a variety of pair statistics and bond-orientational statistics to\ncharacterize the samples. At low defect concentrations, the corresponding\nmaterials are nearly hyperuniform. As more defects are introduced, the\n(approximate) hyperuniformity of the materials is gradually destroyed, and the\nsystem becomes non-hyperuniform even when the material still contains a\nsignificant amount of crystalline regions. At high defect concentrations, the\nstructures become antihyperuniform with diverging (normalized) large-scale\ndensity fluctuations. Overall, the defected materials possess varying degrees\nof orientation order, and there is apparently no intermediate hexatic phase\nemerging. We also construct a minimalist structural model and demonstrate that\nthe experimental samples can be essentially viewed as perturbed honeycomb\ncrystals with small correlated displacements and double chalcogen vacancies."
    },
    {
        "anchor": "Analytic results for the three-sphere swimmer at low Reynolds number: The simple model of a low Reynolds number swimmer made from three spheres\nthat are connected by two arms is considered in its general form and analyzed.\nThe swimming velocity, force--velocity response, power consumption, and\nefficiency of the swimmer are calculated both for general deformations and also\nfor specific model prescriptions. The role of noise and coherence in the stroke\ncycle is also discussed.",
        "positive": "Nonequilibrium self-organization of colloidal particles on substrates:\n  adsorption, relaxation, and annealing: Colloidal particles are considered ideal building blocks to produce materials\nwith enhanced physical properties. The state-of-the-art techniques for\nsynthesizing these particles provide control over shape, size, and\ndirectionality of the interactions. In spite of these advances, there is still\na huge gap between the synthesis of individual components and the management of\ntheir spontaneous organization towards the desired structures. The main\nchallenge is the control over the dynamics of self-organization. In their\nkinetic route towards thermodynamically stable structures, colloidal particles\nself-organize into intermediate (mesoscopic) structures that are much larger\nthan the individual particles and become the relevant units for the dynamics.\nTo follow the dynamics and identify kinetically trapped structures, one needs\nto develop new theoretical and numerical tools. Here we discuss the\nself-organization of functionalized colloids (also known as patchy colloids) on\nattractive substrates. We review our recent results on the adsorption and\nrelaxation and explore the use of annealing cycles to overcome kinetic barriers\nand drive the relaxation towards the targeted structures."
    },
    {
        "anchor": "Two-Dimensional Clusters of Colloidal Spheres: Ground States, Excited\n  States, and Structural Rearrangements: We study experimentally what is arguably the simplest yet non-trivial\ncolloidal system: two-dimensional clusters of 6 spherical particles bound by\ndepletion interactions. These clusters have multiple, degenerate ground states\nwhose equilibrium distribution is determined by entropic factors, principally\nthe symmetry. We observe the equilibrium rearrangements between ground states\nas well as all of the low-lying excited states. In contrast to the ground\nstates, the excited states have soft modes and low symmetry, and their\noccupation probabilities depend on the size of the configuration space reached\nthrough internal degrees of freedom, as well as a single \"sticky parameter\"\nencapsulating the depth and curvature of the potential. Using a geometrical\nmodel that accounts for the entropy of the soft modes and the diffusion rates\nalong them, we accurately reproduce the measured rearrangement rates. The\nsuccess of this model, which requires no fitting parameters or measurements of\nthe potential, shows that the free-energy landscape of colloidal systems and\nthe dynamics it governs can be understood geometrically.",
        "positive": "The polydisperse cell model: Non-linear screening and charge\n  renormalization in colloidal mixtures: We propose a model for the calculation of renormalized charges and osmotic\nproperties of mixtures of highly charged colloidal particles. The model is a\ngeneralization of the cell model and the notion of charge renormalization as\nintroduced by Alexander and his collaborators (J. Chem. Phys. 80, 5776 (1984)).\nThe total solution is partitioned into as many different cells as components in\nthe mixture. The radii of these cells are determined self-consistently for a\ngiven set of parameters from the solution of the non-linear Poisson-Boltzmann\nequation with appropriate boundary conditions. This generalizes Alexanders's\nmodel where the (unique) Wigner-Seitz cell radius is fixed solely by the\ncolloids packing fraction. We illustrate the technique by considering a binary\nmixture of colloids with the same sign of charge. The present model can be used\nto calculate thermodynamic properties of highly charged colloidal mixtures at\nthe level of linear theories, while taking the effect of non-linear screening\ninto account."
    },
    {
        "anchor": "On the mechanisms responsible of photocurrent in bacteriorhodopsin\n  (Bacteriorhodopsin's sense of light): Recently, a growing interest has been addressed to the electrical properties\nof bacteriorhodopsin (bR), a protein belonging to the transmembrane protein\nfamily. To take into account the structure-dependent nature of the current, in\na previous set of papers we suggested a mechanism of sequential tunneling among\nneighbouring amino acids. As a matter of fact, it is well accepted that, when\nirradiated with green light, bR undergoes a conformational change at a\nmolecular level. Thus, the role played by the protein tertiary-structure in\nmodeling the charge transfer cannot be neglected. The aim of this paper is to\ngo beyond previous models, in the framework of a new branch of electronics, we\ncalled proteotronics, which exploits the ability to use proteins as reliable,\nwell understood materials, for the development of novel bioelectronic devices.\nIn particular, the present approach assumes that the conformational change is\nnot the unique transformation that the protein undergoes when irradiated by\nlight. Instead, the light can also promote a free-energy increase of the\nprotein state that, in turn, should modify its internal degree of connectivity,\nhere described by the change in the value of an interaction radius associated\nwith the physical interactions among amino acids. The implemented model enables\nus to achieve a better agreement between theory and experiments in the region\nof a low applied bias by preserving the level of agreement at high values of\napplied bias. Furthermore, results provide new insights on the mechanisms\nresponsible for bR photoresponse.",
        "positive": "Epigenetic Transitions and Knotted Solitons in Stretched Chromatin: The spreading and regulation of epigenetic marks on chromosomes is crucial to\nestablish and maintain cellular identity. Nonetheless, the dynamical mechanism\nleading to the establishment and maintenance of a given, cell-line specific,\nepigenetic pattern is still poorly understood. In this work we propose, and\ninvestigate in silico, a possible experimental strategy to illuminate the\ninterplay between 3D chromatin structure and epigenetic dynamics. We consider a\nset-up where a reconstituted chromatin fibre is stretched at its two ends\n(e.g., by laser tweezers), while epigenetic enzymes (writers) and\nchromatin-binding proteins (readers) are flooded into the system. We show that,\nby tuning the stretching force and the binding affinity of the readers for\nchromatin, the fibre undergoes a sharp transition between a stretched,\nepigenetically disordered, state and a crumpled, epigenetically coherent, one.\nWe further investigate the case in which a knot is tied along the chromatin\nfibre, and find that the knotted segment enhances local epigenetic order,\ngiving rise to \"epigenetic solitons\" which travel and diffuse along chromatin.\nOur results point to an intriguing coupling between 3D chromatin topology and\nepigenetic dynamics, which may be investigated via single molecule experiments."
    },
    {
        "anchor": "Orientational ordering of colloidal dispersions by application of time\n  dependent external forces: We present a method of organizing incoherent motion of a colloidal suspension\nto produce synchronized, coherent motion. This method exploits general features\nof rotational response to time-dependent forcing, and it does not require\ninteraction between the particles. We report two methods of achieving\norientational alignment of an ensemble of identical colloids by means of a\ntime-dependent, but spatially uniform forcing: a) a piecewise constant force\nalternating between two directions and b) a force uniformly rotating about an\naxis. The physical origin of the forcing may be e.g., sedimentation or\nelectrophoresis. We will demonstrate that these forcing methods achieve\nalignment both by analyzing the equations of motion and by simulation. We find\nthe conditions guaranteeing alignment, discuss the limitations of these\nmethods, and suggest possible applications. Examples of such forcing include\nelectrophoresis and sedimentation.",
        "positive": "Velocity profile of granular flows down a heap described by dimensional\n  analysis: Gravity-driven thick granular flows are relevant to many industrial and\ngeophysical processes. In particular, it is important to know and understand\nthe particle velocity distributions as we get deeper into the flow from the\nfree surface. In this paper, we use dimensional analysis as a tool to reproduce\nthe velocity profile experimentally reported for granular flows down a confined\nheap for the so-called flowing layer and the creep layer underneath: the grains\nvelocity first decrease linearly from the free surface, and then exponentially."
    },
    {
        "anchor": "Depinning transition of self-propelled particles: A depinning transition is observed in a variety of contexts when a certain\nthreshold force must be applied to drive a system out of an immobile state. A\nwell-studied example is the depinning of colloidal particles from a corrugated\nlandscape, whereas its active-matter analogue has remained unexplored. We\ndiscuss how active noise due to self-propulsion impacts the nature of the\ntransition: it causes a change of the critical exponent from 1/2 for quickly\nreorienting particles to 3/2 for slowly reorienting ones. In between these\nanalytically tractable limits, the drift velocity exhibits a superexponential\nbehavior as is corroborated by high-precision data. Giant diffusion phenomena\noccur in the two different regimes. Our predictions appear amenable to\nexperimental tests, lay foundations for insight into the depinning of\ncollective variables in active matter, and are relevant for any system with a\nsaddle-node bifurcation in the presence of a bounded noise.",
        "positive": "Transverse electrokinetic and microfluidic effects in micro-patterned\n  channels: lubrication analysis for slab geometries: Off-diagonal (transverse) effects in micro-patterned geometries are predicted\nand analyzed within the general frame of linear response theory, relating\napplied presure gradient and electric field to flow and electric current. These\neffects could contribute to the design of pumps, mixers or flow detectors.\nShape and charge density modulations are proposed as a means to obtain sizeable\ntransverse effects, as demonstrated by focusing on simple geometries and using\nthe lubrication approximation."
    },
    {
        "anchor": "Minimum scaling model and exact exponents for the Nambu-Goldstone modes\n  in the Vicsek Model: We investigate the scaling behavior of Nambu-Goldstone (NG) modes in the\nordered phase of the Vicsek model, introducing a phenomenological equation of\nmotion (EOM) incorporating a previously overlooked non-linear term. This term\narises from the interaction between velocity fields and density fluctuations,\nleading to new scaling behaviors. We derive exact scaling exponents in two\ndimensions, which reproduce the isotropic scaling behavior reported in a prior\nnumerical simulation.",
        "positive": "Diffusion of single long polymers in fixed and low density matrix of\n  obstacles confined to two dimensions: Diffusion properties of a self-avoiding polymer embedded in regularly\ndistributed obstacles with spacing a=20 and confined in two dimensions is\nstudied numerically using the extended bond fluctuation method which we have\ndeveloped recently. We have observed for the first time to our knowledge, that\nthe mean square displacement of a center monomer $\\phi_{M/2}(t)$ exhibits four\ndynamical regimes, i.e., $\\phi_{M/2}(t) \\sim t^{\\nu_m}$ with $\\nu_m\\sim 0.6$,\n3/8, 3/4, and 1 from the shortest to longest time regimes. The exponents in the\nsecond and third regimes are well described by segmental diffusion in the\n``self-avoiding tube''. In the fourth (free diffusion) regime, we have\nnumerically confirmed the relation between the reptation time $\\tau_d$ and the\nnumber of segments $M, \\tau_d\\propto M^3$."
    },
    {
        "anchor": "Interfacial colloidal monolayers under steady shear: structure and flow\n  profiles: We study the coupling between the structural dynamics and rheological\nresponse of charged colloidal monolayers at water/oil interfaces, driven into\nsteady shear by a microdisk rotating at a controlled angular velocity. The flow\ncauses particles to layer into rotating concentric rings linked to the local,\nposition-dependent shear rate, which triggers two distinct dynamical regimes:\nparticles move continuously \"Flowing\") close to the microdisk, or exhibit\nintermittent \"Hopping\" between local energy minima farther away. The shear-rate\ndependent surface viscosity of a monolayer can be extracted from an interfacial\nstress balance, giving \"macroscopic\" flow curves whose behavior corresponds to\nthe distinct microscopic regimes of particle motion. Hopping Regions correspond\nto a surface yield stress $\\eta \\sim \\tau_S^Y \\dot{\\gamma}^{-1}$, whereas\nFlowing Regions exhibit surface viscosities with power-law shear-thinning\ncharacteristics.",
        "positive": "Phase behaviour and dynamics of three-dimensional active dumbbell\n  systems: We present a comprehensive numerical study of the phase behavior and dynamics\nof a three-dimensional active dumbbell system with attractive interactions. We\ndemonstrate that attraction is essential for the system to exhibit nontrivial\nphases. We construct a detailed phase diagram by exploring the effects of the\nsystem's activity, density, and attraction strength. We identify several\ndistinct phases, including a disordered, a gel, and a completely\nphase-separated phase. Additionally, we discover a novel dynamical phase, that\nwe name percolating network, which is characterized by the presence of a\nspanning network of connected dumbbells. In the phase-separated phase we\ncharacterize numerically and describe analytically the helical motion of the\ndense cluster."
    },
    {
        "anchor": "Polar Patterns in Active Fluids: We study the spatio-temporal dynamics of a model of polar active fluid in two\ndimensions. The system exhibits a transition from an isotropic to a polarized\nstate as a function of density. The uniform polarized state is, however,\nunstable above a critical value of activity. Upon increasing activity, the\nactive fluids displays increasingly complex patterns, including traveling\nbands, traveling vortices and chaotic behavior. The advection arising from the\nparticles self-propulsion and unique to polar fluids yields qualitatively new\nbehavior as compared to that obtain in active nematic, with traveling-wave\nstructures. We show that the nonlinear hydrodynamic equations can be mapped\nonto a simplified diffusion-reaction-convection model, highlighting the\nconnection between the complex dynamics of active system and that of excitable\nsystems.",
        "positive": "Analytical solution to the Poisson-Nernst-Planck equations for the\n  charging of a long electrolyte-filled slit pore: We study the charging dynamics of a long electrolyte-filled slit pore in\nresponse to a suddenly applied potential. In particular, we analytically solve\nthe Poisson-Nernst-Planck (PNP) equations for a pore for which $\\lambda_D\\ll\nH\\ll L$, with $\\lambda_D$ the Debye length and $H$ and $L$ the pore's width and\nlength. For small applied potentials, we find the time-dependent potential drop\nbetween the pore's surface and its center to be in complete agreement with a\nprediction of the celebrated transmission line model. For moderate to high\napplied potentials, prior numerical work showed that charging slows down at\nlate times; Our analytical model reproduces and explains such biexponential\ncharge buildup."
    },
    {
        "anchor": "Golden, Quasicrystalline, Chiral Packings of Tetrahedra: Since antiquity, the packing of convex shapes has been of great interest to\nmany scientists and mathematicians. Recently, particular interest has been\ngiven to packings of three-dimensional tetrahedra. Dense packings of both\ncrystalline and semi-quasicrystalline have been reported. It is interesting\nthat a semiquasicrystalline packing of tetrahedra can emerge naturally within a\nthermodynamic simulation approach. However, this packing is not perfectly\nquasicrystalline and the packing density, while dense, is not maximal. Here we\nsuggest that a \"golden rotation\" between tetrahedral facial junctions can\narrange tetrahedra into a perfect quasicrystalline packing.",
        "positive": "Anisotropic Structural Predictor in Glassy Materials: There is a growing evidence that relaxation in glassy materials, both\nspontaneous and externally driven, is mediated by localized soft spots. Recent\nprogress made it possible to identify the soft spots inside glassy structures\nand to quantify their degree of softness. These softness measures, however, are\ntypically scalars, not taking into account the tensorial/anisotropic nature of\nsoft spots, which implies orientation-dependent coupling to external\ndeformation. Here we derive from first principles the linear response coupling\nbetween the local heat capacity of glasses, previously shown to provide a\nmeasure of glassy softness, and external deformation in different directions.\nWe first show that this linear response quantity follows an anomalous,\nfat-tailed distribution related to the universal $\\omega^4$ density of states\nof quasilocalized, nonphononic excitations in glasses. We then construct a\nstructural predictor as the product of the local heat capacity and its linear\nresponse to external deformation, and show that it offers enhanced\npredictability of plastic rearrangements under deformation in different\ndirections, compared to the purely scalar predictor."
    },
    {
        "anchor": "Viscoelasticity and shear flow of concentrated, non-crystallizing\n  colloidal suspensions: Comparison with Mode-Coupling Theory: We present a comprehensive rheological study of a suspension of\nthermosensitive particles dispersed in water. The volume fraction of these\nparticles can be adjusted by the temperature of the system in a continuous\nfashion. Due to the finite polydispersity of the particles (standard deviation:\n17%), crystallization is suppressed and no fluid-crystal transition intervenes.\nHence, the moduli $G'$ and $G\"$ in the linear viscoelastic regime as well as\nthe flow curves (shear stress $\\sigma(\\dot{\\gamma})$ as the function of the\nshear rate $\\dot{\\gamma}$) could be measured in the fluid region up to the\nvicinity of the glass transition. Moreover, flow curves could be obtained over\na range of shear rates of 8 orders of magnitude while $G'$ and $G\"$ could be\nmeasured spanning over 9 orders of magnitude. Special emphasis has been laid on\nprecise measurements down to the smallest shear rates/frequencies. It is\ndemonstrated that mode-coupling theory generalized in the integration through\ntransients framework provides a full description of the flow curves as well as\nthe viscoelastic behavior of concentrated suspensions with a single set of\nwell-defined parameters.",
        "positive": "Recurrent oligomers in proteins - an optimal scheme reconciling accurate\n  and concise backbone representations in automated folding and design studies: A novel scheme is introduced to capture the spatial correlations of\nconsecutive amino acids in naturally occurring proteins. This knowledge-based\nstrategy is able to carry out optimally automated subdivisions of protein\nfragments into classes of similarity. The goal is to provide the minimal set of\nprotein oligomers (termed ``oligons'' for brevity) that is able to represent\nany other fragment. At variance with previous studies where recurrent local\nmotifs were classified, our concern is to provide simplified protein\nrepresentations that have been optimised for use in automated folding and/or\ndesign attempts. In such contexts it is paramount to limit the number of\ndegrees of freedom per amino acid without incurring in loss of accuracy of\nstructural representations. The suggested method finds, by construction, the\noptimal compromise between these needs. Several possible oligon lengths are\nconsidered. It is shown that meaningful classifications cannot be done for\nlengths greater than 6 or smaller than 4. Different contexts are considered\nwere oligons of length 5 or 6 are recommendable. With only a few dozen of\noligons of such length, virtually any protein can be reproduced within typical\nexperimental uncertainties. Structural data for the oligons is made publicly\navailable."
    },
    {
        "anchor": "Brownian dynamics of a self-propelled particle in shear flow: Brownian dynamics of a self-propelled particle in linear shear flow is\nstudied analytically by solving the Langevin equation and in simulation. The\nparticle has a constant propagation speed along a fluctuating orientation and\nis additionally subjected to a constant torque. In two spatial dimensions, the\nmean trajectory and the mean square displacement (MSD) are calculated as\nfunctions of time t analytically. In general, the mean trajectories are\ncycloids that are modified by finite temperature effects. With regard to the\nMSD different regimes are identified where the MSD scales with t^a with a =\n0,1,2,3,4. In particular, an accelerated (a = 4) motion emerges if the particle\nis self-propelled along the gradient direction of the shear flow.",
        "positive": "Extraction du solvant d'un hydrogel par des gouttes de bact\u00e9ries B.\n  subtilis: We observe that small drops of a Bacillus subtilis suspension deposited on\nagar strongly increase in volume while similar bacteria-void drops do not. By\nmeasuring the bacterial concentration within the drop at different heights, we\nshow that the biomass increase due to the constant bacterial cell-division is\ntoo small to explain the drop bloating. Rather, the increased volume is caused\nby the presence of surfactin - a surfactant produced by the bacteria - which\ninduces a water flow out of the environment by an osmotic capillary effect. The\nrequired concentration is very low (< 1 mM), four orders of magnitude smaller\nthan the concentration of, for example, glucose to produce a similar effect.\nThe ability of B. subtilis to extract water from its environment probably\ncontributes to collective migration modes like mass swarming. It also gives\nrise to a new displacement mode independent of cellular motility: By combining\nthe osmotic and wetting effects of the surfactant, B. subtilis can actively\ninduce the sliding of the bacterial colony on substrates tilted by angles as\nsmall as 0.1 degrees."
    },
    {
        "anchor": "Spontaneously rotating clusters of active droplets: We report on the emergence of spontaneously rotating clusters in active\nemulsions. Ensembles of self-propelling droplets sediment and then\nself-organise into planar, hexagonally ordered clusters which hover over the\ncontainer bottom while spinning around the plane normal. This effect exists for\nsymmetric and asymmetric arrangements of isotropic droplets and is therefore\nnot caused by torques due to geometric asymmetries. We found, however, that\nindividual droplets exhibit a helical swimming mode in a small window of\nintermediate activity in a force-free bulk medium. We show that by forming an\nordered cluster, the droplets cooperatively suppress their chaotic dynamics and\nturn the transient instability into a steady rotational state. We analyse the\ncollective rotational dynamics as a function of droplet activity and cluster\nsize and further propose that the stable collective rotation in the cluster is\ncaused by a cooperative coupling between the rotational modes of individual\ndroplets in the cluster.",
        "positive": "Effects of spherical confinement and backbone stiffness on flexible\n  polymer jamming: We use molecular simulations to study jamming of a crumpled bead-spring model\npolymer in a finite container and compare to jamming of repulsive spheres.\nAfter proper constraint counting, the onset of rigidity is seen to occur\nisostatically as in the case of repulsive spheres. Despite this commonality,\nthe presence of the curved container wall and polymer backbone bonds introduce\nnew mechanical properties. Notably, these include additional bands in the\nvibrational density of states that reflect the material structure as well as\noscillations in local contact number and density near the wall but with lower\namplitude for polymers. Polymers have fewer boundary contacts, and this\nlow-density surface layer strongly reduces the global bulk modulus. We further\nshow that bulk-modulus dependence on backbone stiffness can be described by a\nmodel of stiffnesses in series and discuss potential experimental and\nbiological applications."
    },
    {
        "anchor": "Steady advection-diffusion around finite absorbers in two-dimensional\n  potential flows: We perform an exhaustive study of the simplest, nontrivial problem in\nadvection-diffusion -- a finite absorber of arbitrary cross section in a steady\ntwo-dimensional potential flow of concentrated fluid. This classical problem\nhas been studied extensively in the theory of solidification from a flowing\nmelt, and it also arises in Advection-Diffusion-Limited Aggregation. In both\ncases, the fundamental object is the flux to a circular disk, obtained by\nconformal mapping from more complicated shapes. We construct the first accurate\nnumerical solution using an efficient new method, which involves mapping to the\ninterior of the disk and using a spectral method in polar coordinates. Our\nmethod also combines exact asymptotics and an adaptive mesh to handle boundary\nlayers. Starting from a well-known integral equation in streamline coordinates,\nwe also derive new, high-order asymptotic expansions for high and low P\\'eclet\nnumbers ($\\Pe$). Remarkably, the `high' $\\Pe$ expansion remains accurate even\nfor such low $\\Pe$ as $10^{-3}$. The two expansions overlap well near $\\Pe =\n0.1$, allowing the construction of an analytical connection formula that is\nuniformly accurate for all $\\Pe$ and angles on the disk with a maximum relative\nerror of 1.75%. We also obtain an analytical formula for the Nusselt number\n($\\Nu$) as a function of the P\\'eclet number with a maximum relative error of\n0.53% for all possible geometries. Because our finite-plate problem can be\nconformally mapped to other geometries, the general problem of two-dimensional\nadvection-diffusion past an arbitrary finite absorber in a potential flow can\nbe considered effectively solved.",
        "positive": "Moving contact line of a volatile fluid: Interfacial flows close to a moving contact line are inherently multi-scale.\nThe shape of the interface and the flow at meso- and macroscopic scales inherit\nan apparent interface slope and a regularization length, both called after\nVoinov, from the dynamical processes at work at the microscopic level. Here, we\nsolve this inner problem in the case of a volatile fluid at equilibrium with\nits vapor. The evaporative/condensation flux is then controlled by the\ndependence of the saturation temperature on interface curvature -- the\nso-called Kelvin effect. We derive the dependencies of the Voinov angle and of\nthe Voinov length as functions of the substrate temperature. The relevance of\nthe predictions for experimental problems is finally discussed."
    },
    {
        "anchor": "Measuring the dynamic thermal expansivity of molecular liquids near the\n  glass transition: Based on previous works on polymers by Bauer et al. [Phys, Rev. B (2000)],\nthis paper describes a capacitative method for measuring the dynamical\nexpansion coefficient of a viscous liquid. Data are presented for the\nglass-forming liquid tetramethyl tetraphenyl trisiloxane (DC704) in the\nultraviscous regime. Compared to the method of Bauer et al. the dynamical range\nhas been extended by making time-domain experiments and by making very small\nand fast temperature steps. The modelling of the experiment presented in this\npaper includes the situation where the capacitor is not full because the liquid\ncontracts when cooling from room temperature down to around the\nglass-transition temperature, which is relevant when measuring on a molecular\nliquid rather than polymer.",
        "positive": "Thermodynamics predicts a stable microdroplet phase in polymer-gel\n  mixtures undergoing elastic phase separation: We study the thermodynamics of binary mixtures with the volume fraction of\nthe minority component less than the amount required to form a flat interface\nand show that the surface tension dominated equilibrium phase of the mixture\nforms a single macroscopic droplet. Elastic interactions in gel-polymer\nmixtures stabilize a phase with multiple droplets. Using a mean-field free\nenergy we compute the droplet size as a function of the interfacial tension,\nFlory parameter, and elastic moduli of the gel. Our results illustrate the role\nof elastic interactions in dictating the phase behavior of biopolymers\nundergoing liquid-liquid phase separation."
    },
    {
        "anchor": "Experimental evidence of a state-point dependent scaling exponent of\n  liquid dynamics: A large class of liquids have hidden scale invariance characterized by a\nscaling exponent. In this letter we present experimental evidence that the\nscaling exponent of liquid dynamics is state-point dependent for the\nglass-forming silicone oil tetramethyl-tetraphenyl-trisiloxane (DC704) and\n5-polyphenyl ether (5PPE). From dynamic and thermodynamic properties at\nequilibrium, we use a method to estimate the value of $\\gamma$ at any state\npoint of the pressure-temperature plane, both in the supercooled and normal\nliquid regimes. We find agreement between the average exponents and the value\nobtained by superposition of relaxation times over a large range of\nstate-points. We confirm the state-point dependence of $\\gamma$ by reanalyzing\ndata of 20 metallic liquids and two model liquids.",
        "positive": "Smectic elastomer membranes: We present a model for smectic elastomer membranes which includes elastic and\nliquid crystalline degrees of freedom. Based on our model, we determined the\nqualitative phase diagram of a smectic elastomer membrane using mean-field\ntheory. This phase diagram is found to comprise five phases, viz.\nsmectic-A--flat, smectic-A--crumpled, smectic-C--flat, smectic-C--crumpled and\nsmectic-C--tubule, where in the latter phase, the membrane is flat in the\ndirection of mesogenic tilt and crumpled in the perpendicular direction. The\ntransitions between adjacent phases are second order phase transitions. We\nstudy in some detail the elasticity of the smectic-C--flat and the\nsmectic-C--tubule phases which are associated with a spontaneous breaking of\nin-plane rotational symmetry. As a consequence of the Goldstone theorem, these\nphases exhibit soft elasticity characterized by the vanishing of in-plane shear\nmoduli."
    },
    {
        "anchor": "Progressive damage and rupture in polymers: Progressive damage, which eventually leads to failure, is ubiquitous in\nbiological and synthetic polymers. The simplest case to consider is that of\nelastomeric materials, which can undergo large reversible deformations with\nnegligible rate dependence. In this paper, we develop a theory for modeling\nprogressive damage and rupture of such materials. We extend the phase-field\nmethod, which is widely used to describe the damage and fracture of brittle\nmaterials, to elastomeric materials undergoing large deformations. A central\nfeature of our theory is the recognition that the free energy of elastomers is\nnot entirely entropic in nature---there is also an energetic contribution from\nthe deformation of the bonds in the chains. It is the energetic part in the\nfree energy which is the driving force for progressive damage and fracture.",
        "positive": "Spontaneous Unidirectional Loop Extrusion Emerges from Symmetry Breaking\n  of SMC Extension: DNA loop extrusion is arguably one of the most important players in genome\norganization. The precise mechanism by which loop extruding factors (LEFs) work\nis still unresolved and much debated. One of the major open questions in this\nfield is how do LEFs establish and maintain unidirectional motion along DNA. In\nthis paper, we use High-Speed AFM data to show that condensin hinge domain\ndisplays a structural, geometric constraint on the angle within which it can\nextend with respect to the DNA-bound domains. Using computer simulations, we\nthen show that such a geometrical constraint results in a local symmetry\nbreaking and is enough to rectify the extrusion process, yielding\nunidirectional loop extrusion along DNA. Our work highlights an overlooked\ngeometric aspect of the loop extrusion process that may have a universal impact\non SMC function across organisms."
    },
    {
        "anchor": "Iso-electric point of fluid: Iso-electric point(IEP) is the PH, at which the $\\zeta$ potential is measured\nto be zero. The occurrence of IEP has been understood due to the neutralization\nof surface charge density (SCD) at the solid-liquid interface. In this work, we\nuse the potential trap model to study the sources of the surface charge density\nat verious PC and PH, by taking the water-silica system as an example. It is\nrevealed that in the case of $PH<8$, the SCD is mainly originated from the\ndissociation of water molecules. And the bulk ions trapped at the interface can\ndominate the SCD when $PH>9$. Due to the mass action law, the dissociation of\nwater molecules is suppressed at the PH close to IEP, leading to a zero surface\ncharge density. In this way, zero $\\zeta$ potential is obtained at the IEP. It\nhas also been obtained that the increase of the salt concentration in the water\ncan decrease the $\\zeta$ potential, but increase the surface charge density.",
        "positive": "Coarse-grained models of complex fluids at equilibrium and unter shear: Complex fluids exhibit structure on a wide range of length and time scales,\nand hierarchical approaches are necessary to investigate all facets of their\noften unusual properties. The study of idealized coarse-grained models at\ndifferent levels of coarse-graining can provide insight into generic structures\nand basic dynamical processes at equilibrium and non-equilibrium.\n  In the first part of this lecture, some popular coarse-grained models for\nmembranes and membrane systems are reviewed. Special focus is given to\nbead-spring models with different solvent representations, and to\nrandom-interface models. Selected examples of simulations at the molecular and\nthe mesoscopic level are presented, and it is shown how simulations of\nmolecular coarse-grained models can bridge between different levels.\n  The second part addresses simulation methods for complex fluids under shear.\nAfter a brief introduction into the phenomenology (in particular for liquid\ncrystals), different non-equilibrium molecular dynamics (NEMD) methods are\nintroduced and compared to one another. Application examples include the\nbehavior of liquid crystal interfaces and lamellar surfactant phases under\nshear. Finally, mesoscopic simulation approaches for liquid crystals under\nshear are briefly discussed."
    },
    {
        "anchor": "Equilibrium size of large ring molecules: The equilibrium properties of isolated ring molecules were investigated using\nan off-lattice model with no excluded volume but with dynamics that preserve\nthe topological class. Using an efficient set of long range moves, chains of\nmore than 2000 monomers were studied. Despite the lack of any excluded volume\ninteraction, the radius of gyration scaled like that of a self avoiding walk,\nas had been previously conjectured. However this scaling was only seen for\nchains greater than 500 monomers.",
        "positive": "Molecular emulsions: from charge order to domain order: Aqueous mixtures of small molecules, such as lower n-alkanols for example,\nare known to be micro-segregated, with domains in the nano-meter range. One\nconsequence of micro-segregated domains would be the existence of long range\ndomain-domain oscillatory correlations in the various atom- atom pair\ncorrelation functions, and subsequent pre-peaks in the corresponding atom atom\nstructure factors, in the q-vector range corresponding to nano-sized domains.\nHowever, no such pre-peak have ever been observed in the large corpus of\nradiation scattering data published so far. Here, through large scale\nsimulations of aqueous-1propanol mixtures, I report that the domain pre-peak\ncontributions in the atom-atom structure factors exactly cancel each other in\nthe total scattering intensity, thus suppressing the pre-peak in agreement with\nthe experimental findings. This cancellation is explained by drawing an analogy\nbetween the charge order found in ionic fluids and the segregated domain order.\nThis finding opens new interpretation of the well known scattering pre-peak\nobserved in micro-emulsions. In particular, it implies that scattering\nexperiment cannot detect homogeneous domain segregation, hence cannot lead to a\nproper microscopic description of atom-atom correlations in domain ordered\nmixtures."
    },
    {
        "anchor": "Fast dynamics in glass-forming salol investigated by dielectric\n  spectroscopy: We analyze dielectric-loss spectra of glass forming salol extending up to 400\nGHz allowing for the detection of the high-frequency minimum, where the fast\ncritical dynamics predicted by the mode-coupling theory of the glass transition\nshould prevail. Indeed, we find such a minimum which, moreover, well fulfills\nthe critical scaling predicted by the theory. This includes the spectral shape\nof the minimum, the critical temperature dependence of the minimum frequency\nand amplitude, and the critical temperature dependence of the alpha-relaxation\nrate at high temperatures. The minimum exponents a and b leading to a system\nparameter lambda = 0.63 and the critical temperature Tc = 256 K are all in\nreasonable agreement with previous investigations of salol using different\nmethods. Salol was one of the first materials where mode-coupling theory was\ntested and initial dielectric measurements were taken as an argument against\nthe universal applicability of this theory.",
        "positive": "A simple statistical-mechanical interpretation of Onsager reciprocal\n  relations and Derjaguin theory of thermo-osmosis: The application of a temperature gradient along a fluid-solid interface\ngenerates stresses in the fluid causing \"thermo-osmotic\" flow. Much of the\nunderstanding of this phenomenon is based on Derjaguin's work relating\nthermo-osmotic flows to the mechano-caloric effect, namely, the interfacial\nheat flow induced by a pressure gradient. This is done by using Onsager's\nreciprocity relationship for the equivalence of the thermo-osmotic and\nmechano-caloric cross-term transport coefficients. Both Derjaguin theory and\nOnsager framework for out-of-equilibrium systems are formulated in macroscopic\nthermodynamics terms and lack a clear interpretation at the molecular level.\nHere, we use statistical-mechanical tools to derive expressions for the\ntransport cross-coefficients and, thereby, to directly demonstrate their\nequality. This is done for two basic models: (i) an incopressible continuum\nsolvent containing non-interacting solute particles, and (ii) a\nsingle-component fluid without thermal expansivity. The derivation of the\nmechano-caloric coefficient appears to be remarkably simple, and provides a\nsimple interpretation for the connection between interfacial heat and particle\nfluxes. We use this interpretation to consider yet another example, which is an\nelectrolyte interacting with a uniformly-charged surface in the strong\nscreening (Debye-H\\\"uckel) regime."
    },
    {
        "anchor": "Colloidal crystal growth at externally imposed nucleation clusters: We study the conditions under which and how an imposed cluster of fixed\ncolloidal particles at prescribed positions triggers crystal nucleation from a\nmetastable colloidal fluid. Dynamical density functional theory of freezing and\nBrownian dynamics simulations are applied to a two-dimensional colloidal system\nwith dipolar interactions. The externally imposed nucleation clusters involve\ncolloidal particles either on a rhombic lattice or along two linear arrays\nseparated by a gap. Crystal growth occurs after the peaks of the nucleation\ncluster have first relaxed to a cutout of the stable bulk crystal.",
        "positive": "Phase Phenomena in Supported Lipid Films under Varying Electric\n  Potential: We model cyclic voltammetry experiments on supported lipid films where a\nnon-trivial dependence of the capacitance on the applied voltage is observed.\nPreviously, based on a mean-field treatment of the Flory-Huggins type, under\nthe assumption of strongly screened electrostatic interactions, it has been\nhypothesized that peaks in the capacitance-vs-voltage profiles correspond to a\nsequence of structural or phase transitions within the interface. To examine\nthis hypothesis, in this study we use both mean-field calculations and Monte\nCarlo simulations where the electrostatic effects due to the varying electric\npotential and the presence of salt are accounted for explicitly. Our main focus\nis on the structure of the film and the desorption-readsorption phenomena.\nThese are found to be driven by a strong competition for the progressively\ncharged-up (hydrophobic) surface between lipid hydrocarbon tails and the\nelectrode counterions (cations). As the surface charge density is raised, the\nfollowing phase phenomena within the interface are clearly observed: (i) a\ngradual displacement of the monolayer from the surface by the counterions,\nleading to complete monolayer desorption and formation of an electric double\nlayer by the surface, (ii) a transformation of the monolayer into a bilayer\nupon its desorption, (iii) in the case of zwitterionic (or strongly polar)\nlipid head groups, the desorption is followed by the bilayer readsorption to\nthe electrode via interaction with the electric double layer and release of the\nexcess counterions into the bulk solution. We argue then that the voltammetry\npeaks are associated with a stepwise process of formation of layers of\nalternating charge: electric double layer - upon film desorption, triple or\nmulti-layer - upon film readsoption."
    },
    {
        "anchor": "Ising-like critical behavior of vortex lattices in an active fluid: Turbulent vortex structures emerging in bacterial active fluids can be\norganized into regular vortex lattices by weak geometrical constraints such as\nobstacles. Here we show, using a continuum-theoretical approach, that the\nformation and destruction of these patterns exhibit features of a continuous\nsecond-order equilibrium phase transition, including long-range correlations,\ndivergent susceptibility, and critical slowing down. The emerging vorticity\nfield can be mapped onto a two-dimensional (2D) Ising model with\nantiferromagnetic nearest-neighbor interactions by coarse-graining. The\nresulting effective temperature is found to be proportional to the strength of\nthe nonlinear advection in the continuum model.",
        "positive": "Assessment of exchange-correlation functionals for the calculation of\n  dynamical properties of small clusters in TDDFT: We present a detailed study of different exchange-correlation (xc)\nfunctionals in describing the dynamical properties of finite systems. For that\npurpose, we calculated the static polarizabilities, ionization potentials and\noptical absorption spectrum of four small clusters, Na_2, Na_4, SiH_4 and\nSi_2H_6, using a real-space, real-time technique. The computed static\npolarizabilities and ionization potentials seem to be in rather good agreement\nwith the available experimental data, once the proper asymptotics of the\npotential are taken into account. The same conclusion holds for the absorption\nspectra, although the xc kernels in use do not provide a sufficiently strong\nattractive interaction between electrons and holes, leading to spectra slightly\nshifted towards higher energies. This deficiency is traced back to the\ninsufficient description of dynamical effects in the correlation functional.\nFurthermore, it is shown that the xc potential used to obtain the ground state\nis the key factor to get reasonable spectra, whereas the choice of the xc\nkernel just amounts to small, although important, quantitative changes."
    },
    {
        "anchor": "Anisotropic swelling due to hydration in fibrous biomaterials: Naturally occurring protein fibres often undergo anisotropic swelling when\nhydrated. Within a tendon, a hydrated collagen fibril's radius expands by 40\\%\nbut its length only increases by 5\\%. The same effect, with similar magnitude,\nis observed for keratin microfibrils within hair. Nevertheless, current\nexplanations for swelling anisotropy are based on molecular details that are\nunique to each material. Here, we describe a coarse-grained liquid-crystalline\nelastomer model for biomaterial hydration that allows for anisotropic swelling.\nWe show that our model is consistent with previously observed behavior for both\nhair fibers and collagen fibrils. Despite a non-linear relationship between\nwater saturation and relative humidity, we find that the squared deformation in\nthe axial and radial directions is approximately linear with water saturation.\nWe further find that anisotropic swelling is linear with respect to volume and\nshape changes. Hair and collagen exhibit remarkably similar behavior under\nhydration. We suggest that our model may also be useful for other biomaterials\nthat exhibit anisotropic swelling.",
        "positive": "Influence of asymmetric depletion of solvents on the electric double\n  layer of charged objects in binary polar solvent mixture: For binary solvent mixtures composed of ions and two kinds of polar solvents,\nelectric double layer near a charged object is strongly affected by not only\nthe binary solvent composition but also nature of solvents such as volume and\ndipole moment of a solvent molecule. Accounting for difference in sizes of\nsolvents and orientational ordering of solvent dipoles, we theoretically obtain\ngeneral expressions for the spatial distribution functions of solvents and\nions, in planar geometry and within the mean-field approach. Although focusing\non long-range electrostatic interaction, we neglect short-range interactions\nsuch as preferential solvation, our approach predicts an asymmetric depletion\nof the two solvents from the charged surface and a behavior of decreased\npermittivity of the binary solvent mixture. Furthermore, we suggest that the\nkey factor for the depletion is the ratio of the solvent dipole moment to the\nsolvent volume. The influence of binary solvent composition, volume of solvent\nand dipole moment of solvent on the number density of solvents, permittivity\nand differential capacitance are presented and discussed, respectively. We\nconclude that accounting for difference in the volume and dipole moment between\npolar solvents is necessary for new approach to represent more realistic\nsituations such as preferential solvation."
    },
    {
        "anchor": "Self-oscillation and Synchronisation Transitions in Elasto-Active\n  Structures: The interplay between activity and elasticity often found in active and\nliving systems triggers a plethora of autonomous behaviors ranging from\nself-assembly and collective motion to actuation. Amongst these, spontaneous\nself-oscillations of mechanical structures is perhaps the simplest and most\nwide-spread type of non-equilibrium phenomenon. Yet, we lack experimental model\nsystems to investigate the various dynamical phenomena that may appear. Here,\nwe report self-oscillation and synchronization transitions in a\ncentimeter-sized model system for one-dimensional elasto-active structures. By\ncombining precision-desktop experiments of elastically coupled self-propelled\nparticles with numerical simulations and analytical perturbative theory, we\ndemonstrate that the dynamics of single chain follows a Hopf bifurcation. We\nshow that this instability is controlled by a single non-dimensional\nelasto-active number that quantifies the interplay between activity and\nelasticity. Finally, we demonstrate that pairs of coupled elasto-active chains\ncan undergo a synchronization transition: the oscillations phases of both\nchains lock when the coupling link is sufficiently stiff. Beyond the canonical\ncase considered here, we anticipate our work to open avenues for the\nunderstanding and design of the self-organisation and response of active\nartificial and biological solids, e.g. in higher dimensions and for more\nintricate geometries.",
        "positive": "What determines static force chains in stressed granular media?: The determination of the normal and transverse (frictional) inter-particle\nforces within a granular medium is a long standing, taunting, and yet\nunresolved problem. We present a new formalism which employs the knowledge of\nthe external forces and the orientations of contacts between particles (of any\ngiven sizes), to compute all the inter-particle forces. Having solved this\nproblem we exemplify the efficacy of the formalism showing that the force\nchains in such systems are determined by an expansion in the eigenfunctions of\na newly defined operator."
    },
    {
        "anchor": "The effect of combined roundness and polydispersity on the phase\n  behavior of hard-rectangle fluids: We introduce a model for a fluid of polydisperse rounded hard rectangles\nwhere the length and width of the rectangular core are fixed, while the\nroundness is taken into account by the convex envelope of a disk displaced\nalong the perimeter of the core. The diameter of the disk has a continuous\npolydispersity described by a Schultz distribution function. We implemented the\nscaled particle theory for this model with the aim to studying: (i) the effect\nof roundness on the phase behavior of the one-component hard-rectangle fluid,\nand (ii) how polydispersity affects phase transitions between isotropic,\nnematic and tetratic phases. We found that roundness greatly affects the\ntetratic phase, whose region of stability in the phase diagram strongly\ndecreases as the roundness parameter is increased. Also the interval of aspect\nratios where the tetratic-nematic and isotropic-nematic phase transitions are\nof first order considerably reduces with roundness, both transitions becoming\nweaker. Polydispersity induces strong fractionation between the coexisting\nphases, with the nematic phase enriched in particles of lower roundness.\nFinally, for high enough polydispersity and certain mean aspect ratios, the\nisotropic-to-nematic transition can change from second (for the one-component\nfluid) to first order. We also found a packing-fraction inversion phenomenon\nfor large polydispersities: the coexisting isotropic phase has a higher packing\nfraction than the nematic.",
        "positive": "Quantum Numbers for Excitations of Bose-Einstein Condensates in 1D\n  Optical Lattices: The excitation spectrum and the band structure of a Bose-Einstein condensate\nin a periodic potential are investigated. Analyses within full 3D systems,\nfinite 1D systems, and ideal periodic 1D systems are compared. We find two\nbranches of excitations in the spectra of the finite 1D model. The band\nstructures for the first and (part of) the second band are compared between a\nfinite 1D and the fully periodic 1D systems, utilizing a new definition of a\neffective wavenumber and a phase-slip number. The upper and lower edges of the\nfirst gap coincide well between the two cases. The remaining difference is\nexplained by the existence of the two branches due to the finite-size effect."
    },
    {
        "anchor": "Cell motility: a viscous fingering analysis of active gels: The symmetry breaking of the actin network from radial to longitudinal\nsymmetry has been identified as the major mechanism for keratocytes (fish\ncells) motility on solid substrate. For strong friction coefficient, the two\ndimensional actin flow which includes the polymerisation at the edge and\ndepolymerisation in the bulk can be modelled as a Darcy flow, the cell shape\nand dynamics being then modelled by standard complex analysis methods. We use\nthe theory of active gels to describe the orientational order of the filaments\nwhich varies from the border to the bulk. We show analytically that the\nreorganisation of the cortex is enough to explain the motility of the cell and\nfind the velocity as a function of the orientation order parameter in the bulk.",
        "positive": "Scaling in rupture of polymer chains: We consider the rupture dynamics of a homopolymer chain pulled at one end at\na constant loading rate r. Compared to single bond breaking, the existence of\nthe chain introduces two new aspects into rupture dynamics: the non-Markovian\naspect in the barrier crossing and the slow-down of the force propagation to\nthe breakable bond. The relative impact of both these processes is\ninvestigated, and the second one was found to be the most important at moderate\nloading rates. The most probable rupture force is found to decrease with the\nnumber of bonds as f_{max} const-(ln(N/r))^(2/3) and finally to approach a\nsaturation value independent on N. All our analytical findings are confirmed by\nextensive numerical simulations."
    },
    {
        "anchor": "A Retrofit Sensing Strategy for Soft Fluidic Robots: Soft robots are intrinsically capable of adapting to different environments\nby changing their shape in response to interaction forces with the environment.\nHowever, sensing and feedback are still required for higher level decisions and\nautonomy. Most sensing technologies developed for soft robots involve the\nintegration of separate sensing elements in soft actuators, which presents a\nconsiderable challenge for both the fabrication and robustness of soft robots\ndue to the interface between hard and soft components and the complexity of the\nassembly. To circumvent this, here we present a versatile sensing strategy that\ncan be retrofitted to existing soft fluidic devices without the need for design\nchanges. We achieve this by measuring the fluidic input that is required to\nactivate a soft actuator and relating this input to its deformed state during\ninteraction with the environment. We demonstrate the versatility of our sensing\nstrategy by tactile sensing of the size, shape, surface roughness and stiffness\nof objects. Moreover, we demonstrate our approach by retrofitting it to a range\nof existing pneumatic soft actuators and grippers powered by positive and\nnegative pressure. Finally, we show the robustness of our fluidic sensing\nstrategy in closed-loop control of a soft gripper for practical applications\nsuch as sorting, fruit picking and ripeness detection. Based on these results,\nwe conclude that as long as the interaction of the actuator with the\nenvironment results in a shape change of the interval volume, soft fluidic\nactuators require no embedded sensors and design modifications to implement\nuseful sensing. We believe that the relative simplicity, versatility, broad\napplicability and robustness of our sensing strategy will catalyze new\nfunctionalities in soft interactive devices and systems, thereby accelerating\nthe use of soft robotics in real world applications.",
        "positive": "Hydrodynamics of an odd active surfer in a chiral fluid: We theoretically and computationally study the low-Reynolds-number\nhydrodynamics of a linear active microswimmer surfing on a compressible thin\nfluid layer characterized by an odd viscosity. Since the underlying\nthree-dimensional fluid is assumed to be very thin compared to any lateral size\nof the fluid layer, the model is effectively two-dimensional. In the limit of\nsmall odd viscosity compared to the even viscosities of the fluid layer, we\nobtain analytical expressions for the self-induced flow field, which includes\nnon-reciprocal components due to the odd viscosity. On this basis, we fully\nanalyze the behavior of a single linear swimmer, finding that it follows a\ncircular path, the radius of which is, to leading order, inversely proportional\nto the magnitude of the odd viscosity. In addition, we show that a pair of\nswimmers exhibits a wealth of two-body dynamics that depends on the initial\nrelative orientation angles as well as on the propulsion mechanism adopted by\neach swimmer. In particular, the pusher-pusher and pusher-puller-type swimmer\npairs exhibit a generic spiral motion, while the puller-puller pair is found to\neither co-rotate in the steady state along a circular trajectory or exhibit a\nmore complex chaotic behavior resulting from the interplay between hydrodynamic\nand steric interactions. Our theoretical predictions may pave the way toward a\nbetter understanding of active transport in active chiral fluids with odd\nviscosity, and may find potential applications in the quantitative\nmicrorheological characterization of odd-viscous fluids."
    },
    {
        "anchor": "Real-space model for activated processes in rejuvenation and memory\n  behavior of glassy systems: We offer an alternative real-space description based purely on activated\nprocesses for the understanding of relaxation dynamics in hierarchical\nlandscapes. To this end, we use the cluster model, a coarse-grained lattice\nmodel of a jammed system, to analyze rejuvenation and memory effects during\naging after a hard quench. In this model, neighboring particles on a lattice\naggregate through local interactions into clusters that fragment with a\nprobability based on their size. Despite the simplicity of the cluster model,\nit has been shown to reproduce salient observables of the aging dynamics in\ncolloidal systems, such as those accounting for particle mobility and\ndisplacements. Here, we probe the model for more complex quench protocols and\nshow that it exhibits the same rejuvenation and memory effects attributed to\nthe complex hierarchical structure of a glassy energy landscape. Beyond\nstudying rejuvenation and memory effects, we also demonstrate that this model\ncan be used for predictive purposes on the end of memory.",
        "positive": "Rheology of 2D vertex model: The mechanical properties of tissues play an essential role for all tissue\nproperties such as cell division, and differentiation or morphogenesis. Here,\nwe study theoretically the rheology of 2-dimensional epithelial tissues\ndescribed by a discrete vertex-like model, using an analytical coarsegrained\ncontinuum formulation. We show that epithelial tissues are most often\nshear-thinning under constant shear rate, and in certain circumstances cross\nover from shear thickening at low shear rates to shear thinning at high shear\nrates. We give an analytical expression of the tissue response in an\noscillating strain experiment in the linear regime, and calculate it\nnumerically in the non-linear regime. When the tissue is supported by an\noscillating substrate, it reorients depending on frequency and substrate's\nPoisson's ratio. Reorientation could be gradual or abrupt, depending on tissue\nand substrate parameters, and the configuration phase space exhibits a\ntricritical point."
    },
    {
        "anchor": "A fast adhesive discrete element method for random packings of fine\n  particles: Introducing a reduced particle stiffness in discrete element method (DEM)\nallows for bigger time steps and therefore fewer total iterations in a\nsimulation. Although this approach works well for dry non-adhesive particles,\nit has been shown that for fine particles with adhesion, system behaviors are\ndrastically sensitive to the particle stiffness. Besides, a simple and\napplicable principle to set the parameters in adhesive DEM is also lacking. To\nsolve these two problems, we first propose a fast DEM based on scaling laws to\nreduce particle Young's modulus, surface energy and to modify rolling and\nsliding resistances simultaneously in the framework of Johnson-Kendall-Roberts\n(JKR)-based contact theory. A novel inversion method is then presented to help\nusers to quickly determine the damping coefficient, particle stiffness and\nsurface energy to reproduce a prescribed experimental result. After validating\nthis inversion method, we apply the fast adhesive DEM to packing problems of\nmicroparticles. Measures of packing fraction, averaged coordination number and\ndistributions of local packing fraction and contact number of each particle are\nin good agreement with results simulated using original value of particle\nproperties. The new method should be helpful to accelerate DEM simulations for\nsystems associated with aggregates or agglomerates.",
        "positive": "Active osmotic-like pressure on permeable inclusions: We use active Brownian model to study effective pressure produced by active\nfluids on a fixed permeable inclusion whose interior and exterior regions are\ncharacterized by different particle motilities. We consider both rectangular\nand disklike inclusions and investigate the role of mismatching\ninterior/exterior motility in the osmotic-like (effective) pressure which is\nexerted by active particles on the enclosing membrane of the inclusions. We\nfind two different traits in the regimes of small and large motility strengths.\nIn the former case, active pressure is sensitive to initial conditions. Given\nan initial condition where active particles are homogeneously distributed in\nthe environment, active pressure is found to be higher in the region with\nhigher motility. By contrast, in the regime of strong motility, active pressure\nis nonsensitive to initial conditions and is found to be higher in the region\nwith lower motility. This difference arises from the ability of active\nparticles to go through the membrane enclosure. In the weak motility regime,\nactive particles are unable to permeate through the membrane, maintaining the\nsame concentration inside and outside the inclusion as established by initial\nconditions; hence, expectedly, active pressure is higher in the region of\nhigher motility strength. In the strong motility regime, active particles\naccumulate preferentially in the region of lower motility strength where they\nproduce a respectively higher active pressure."
    },
    {
        "anchor": "A new Bloch period for interacting cold atoms in 1D optical lattices: The paper studies Bloch oscillations of ultracold atoms in optical lattice in\nthe presence of atom-atom interaction. A new, interaction-induced Bloch period\nis identified. The analytical results are corroborated by realistic numerical\ncalculations.",
        "positive": "Theory for the nonequilibrium dynamics of flexible chain molecules:\n  relaxation to equilibrium of pentadecane from an all-trans conformation: We extend to nonequilibrium processes our recent theory for the long time\ndynamics of flexible chain molecules. While the previous theory describes the\nequilibrium motions for any bond or interatomic separation in (bio)polymers by\ntime correlation functions, the present extension of the theory enables the\nprediction of the nonequilibrium relaxation that occurs in processes, such as\nT-jump experiments, where there are sudden transitions between, for example,\ndifferent equilibrium states. As a test of the theory, we consider the\n``unfolding'' of pentadecane when it is transported from a constrained\nall-trans conformation to a random-coil state at thermal equilibrium. The time\nevolution of the mean-square end-to-end distance after release of the\nconstraint is computed both from the theory and from Brownian dynamics (BD)\nsimulations. The predictions of the theory agree very well with the BD\nsimulations. Furthermore, the theory produces enormous savings in computer\ntime. This work is a starting point for the application of the new method to\nnonequilibrium processes with biological importance such as the helix-coil\ntransition and protein folding."
    },
    {
        "anchor": "Temperature-driven anchoring transitions at liquid crystal / water\n  interfaces: Controlling the anchoring of liquid crystal molecules at an interface with a\nwater solution influences the entire organization of the underlying liquid\ncrystal phase, which is crucial for many applications. The simplest way to\nstabilize such interfaces is by fabricating droplets of liquid crystal in\nwater; however, a greater sensitivity to interfacial effects can be achieved\nusing liquid crystal shells, i.e. spherical films of liquid crystal suspended\nin water. Anchoring transitions on those systems are traditionally triggered by\nthe adsorption of surfactant molecules onto the interface, which is neither an\ninstantaneous nor a reversible process. In this study, we report the ability to\nchange the anchoring of 4-cyano-4'-pentylbiphenyl (5CB), one of the most widely\nused liquid crystals, at the interface with dilute water solutions of polyvinyl\nalcohol (PVA), a polymer commonly used for stabilizing liquid crystal shells,\nsimply by controlling the temperature in the close vicinity of the liquid\ncrystal clearing point. A quasi-static increase in temperature triggers an\ninstantaneous reorientation of the molecules from parallel to perpendicular to\nthe interfaces, owing to the local disordering effect of PVA on 5CB, prior to\nthe phase transition of the bulk 5CB. We study this anchoring transition on\nboth flat suspended films and spherical shells of liquid crystals. Switching\nanchoring entails a series of structural transformations involving the\nformation of transient structures in which topological defects are stabilized.\nThe type of defect structure depends on the topology of the film. This method\nhas the ability to influence both interfaces of the film nearly at the same\ntime, and can be applied to transform an initially polydisperse group of\nnematic shells into a monodisperse population of bivalent shells.",
        "positive": "Differently Shaped Hard Body Colloids in Confinement: From passive to\n  active particles: We review recent progress in the theoretical description of anisotropic hard\ncolloidal particles. The shapes considered range from rods and dumbbells to\nrounded cubes, polyhedra and to biaxial particles with arbitrary shape. Our\nfocus is on both static and dynamical density functional theory and on computer\nsimulations. We describe recent results for the structure, dynamics and phase\nbehaviour in the bulk and in various confining geometries, e.g. established by\ntwo parallel walls which reduce the dimensionality of the system to two\ndimensions. We also include recent theoretical modelling for active particles,\nwhich are autonomously driven by some intrinsic motor, and highlight their\nfascinating nonequilibrium dynamics and collective behaviour."
    },
    {
        "anchor": "Anomalous diffusion on random graphs: We show that anomalous diffusion can result when the steps of a random walk\nare not statistically independent. We present an algorithm that counts all the\npossible paths of particles diffusing on random graphs with arbitrary degree\ndistribution. Using this to calculate the mean square displacement, we show\nthat in sharp contrast to continua, random walks on random graphs can exhibit\nanomalous behavior and yet have well-defined and predictable properties.",
        "positive": "Controlling the size and adhesion of DNA droplets using surface-active\n  DNA molecules: Liquid droplets of biomolecules serve as organizers of the cellular interior\nand are of interest in biosensing and biomaterials applications. Here, we\ninvestigate means to tune the interfacial properties of a model biomolecular\nliquid consisting of multi-armed DNA 'nanostar' particles. We find that long\nDNA molecules that have binding affinity for the nanostars are preferentially\nenriched on the interface of nanostar droplets, thus acting as surfactants.\nFluorescent measurements indicate that, in certain conditions, the interfacial\ndensity of the surfactant is around 20 per square micron, indicative of a\nsparse brush-like structure of the long, polymeric DNA. Increasing surfactant\nconcentration leads to decreased droplet size, down to the sub-micron scale,\nconsistent with arrest of droplet coalescence by the disjoining pressure\ncreated by the brush-like surfactant layer. Added DNA surfactant also keeps\ndroplets from adhering to both hydrophobic and hydrophilic solid surfaces,\napparently due to this same disjoining effect of the surfactant layer. We thus\ndemonstrate control of the size and adhesive properties of droplets of a\nbiomolecular liquid, with implications for basic biophysical understanding of\nsuch droplets, as well as for their applied use."
    },
    {
        "anchor": "Non-equilibrium hydrodynamics of a rotating filament: The nonlinear dynamics of an elastic filament that is forced to rotate at its\nbase is studied by hydrodynamic simulation techniques; coupling between\nstretch, bend, twist elasticity and thermal fluctuations is included. The\ntwirling-overwhirling transition is located and found to be strongly\ndiscontinuous. For finite bend and twist persistence length, thermal\nfluctuations lower the threshold rotational frequency, for infinite persistence\nlength the threshold agrees with previous analytical predictions.",
        "positive": "Diffusion of a sphere in a dilute solution of polymer coils: We calculate the short time and the long time diffusion coefficient of a\nspherical tracer particle in a polymer solution in the low density limit by\nsolving the Smoluchowski equation for a two-particle system and applying a\ngeneralized Einstein relation (fluctuation dissipation theorem). The tracer\nparticle as well as the polymer coils are idealized as hard spheres with a\nno-slip boundary condition for the solvent but the hydrodynamic radius of the\npolymer coils is allowed to be smaller than the direct-interaction radius. We\ntake hydrodynamic interactions up to 11th order in the particle distance into\naccount. For the limit of small polymers, the expected generalized\nStokes-Einstein relation is found. The long time diffusion coefficient also\nroughly obeys the generalized Stokes-Einstein relation for larger polymers\nwhereas the short time coefficient does not. We find good qualitative and\nquantitative agreement to experiments."
    },
    {
        "anchor": "Network Topology in Water Nanoconfined between Phospholipid Membranes: Water provides the driving force for the assembly and stability of many\ncellular components. Despite its impact on biological functions, a nanoscale\nunderstanding of the relationship between its structure and dynamics under soft\nconfinement has remained elusive. As expected, water in contact with biological\nmembranes recovers its bulk density and dynamics at $\\sim 1$ nm from\nphospholipid headgroups but surprisingly enhances its intermediate-range order\n(IRO) over a distance, at least, twice as large. Here, we explore how the IRO\nis related to the water's hydrogen bond network (HBN) and its coordination\ndefects. We characterize the increased IRO by an alteration of the HBN up to\nmore than eight coordination shells of hydration water. The HBN analysis\nemphasizes the existence of a bound-unbound water interface at $\\sim 0.8$ nm\nfrom the membrane. The unbound water has a distribution of defects intermediate\nbetween bound and bulk water, but with density and dynamics similar to bulk,\nwhile bound water has reduced thermal energy and much more HBN defects than\nlow-temperature water. This observation could be fundamental for developing\nnanoscale models of biological interactions and for understanding how\nalteration of the water structure and topology, for example, due to changes in\nextracellular ions concentration, could affect diseases and signaling. More\ngenerally, it gives us a different perspective to study nanoconfined water.",
        "positive": "Three-dimensional Binary Superlattices of Oppositely-charged Colloids: We report the equilibrium self-assembly of binary crystals of\noppositely-charged colloidal microspheres at high density. By varying the\nmagnitude of the charge on near equal-sized spheres we show that the structure\nof the binary crystal may be switched between face-centered cubic, cesium\nchloride and sodium chloride. We interpret these transformations in terms of a\ncompetition between entropic and Coulombic forces."
    },
    {
        "anchor": "Complex Transport Phenomena in a Simple Lattice Gas System: The transport phenomena of a nonequilibrium lattice gas system are\ninvestigated. We consider a simple system that consists of two particles\ninteracting repulsively and the potential forces acting on these particles.\nUnder an external driving field applied to only one particle, we found the\nfollowing relation between the mean velocity of the driven particle and the\ncoefficient of effective drag of this particle under certain conditions; With\nthe increase in the mean velocity, the coefficient of effective drag varies in\nthe form, increase $\\to$ decrease $\\to$ increase $\\to$ decrease. Moreover,\nunder other conditions, we found the following relations between these values\nwhich show changes similar to those between shear rate and shear viscosity\nobserved in the shear-thickening polymer or colloidal suspensions; With the\nincrease in the mean velocity, the coefficient of effective drag varies in the\nform, increase $\\to$ decrease or decrease $\\to$ increase $\\to$ decrease. We\nexplain the mechanisms of such phenomena by considering the transition\ndiagrams.",
        "positive": "Optimisation of hierarchical dielectric elastomer laminated composites: This paper is concerned with the optimisation of the actuation response of\nelectro-elastic, rank-two laminates obtained laminating a core rank-one\ncomposite with a soft phase which constitutes the shell. The analysis is\nperformed for two classes of composites that are subjected to traction-free\nboundary-value problems. The results are compared with those computed in a\nprevious study where the optimisation was carried out at small strains. The\nnon-linear approach allows a better estimation of the geometric layout of the\nreference configuration to enhance the maximum stretch or shear strain at the\noperative applied voltage. The optimum layouts are in general characterised by\na very low volume fraction of the shell while in the core the two components\nare almost equally distributed. The amplification of the electric field in each\nphase of the laminate in the actuated state is also estimated to provide an\nindication of the effective local electro-mechanical response."
    },
    {
        "anchor": "Mechanism of pressure sensitive adhesion in nematic elastomers: Nematic liquid crystal elastomers (LCEs) have anomalously high vibration\ndamping, and it has been assumed this is the cause of their anomalously high\npressure-sensitive adhesion (PSA). Here we investigate the mechanism behind\nthis enhanced PSA by first preparing thin adhesive tapes with LCE of varying\ncrosslinking density, characterizing their material and surface properties, and\nthen studying the adhesion characteristics with a standard set of 90-deg peel,\nlap shear, and probe tack tests. The study confirms that the enhanced PSA is\nonly present in (and due to) the nematic phase of the elastomer, and the\nstrength of bonding takes over 24 hours to fully reach its maximum value. Such\na long saturation time is caused by the slow relaxation of local stress and\ndirector orientation in nematic domains after pressing against the surface. We\nconfirm this mechanism by showing that a freshly pressed and annealed tape\nreaches the same maximum bonding strength on cooling, when the returning\nnematic order is forming in its optimal configuration in the pressed film.",
        "positive": "Velocity Distributions & Density Fluctuations in a 2D Granular Gas: Velocity distributions in a vibrated granular monolayer are investigated\nexperimentally. Non-Gaussian velocity distributions are observed at low\nvibration amplitudes but cross over smoothly to Gaussian distributions as the\namplitude is increased. Cross-correlations between fluctuations in density and\ntemperature are present only when the velocity distributions are strongly\nnon-Gaussian. Confining the expansion of the granular layer results in\nnon-Gaussian velocity distributions that persist to high vibration amplitudes."
    },
    {
        "anchor": "Structure and stimuli-responsiveness of all-DNA dendrimers: theory and\n  experiment: We present a comprehensive theoretical and experimental study of the solution\nphase properties of DNA-based family of nanoparticles - dendrimer-like DNA\nmolecules (DL-DNA). These charged DNA dendrimers are novel macromolecular\naggregates, which hold high promise in targeted self-assembly of soft matter\nsystems in the bulk and at interfaces. To describe the behavior of this family\nof dendrimers (with generations ranging from G1 to G7), we use a theoretical\nmodel in which base-pairs of a single DL-DNA molecule are modeled by charged\nmonomers, whose interactions are chosen to mimic the equilibrium properties of\nDNA correctly. Experimental results on the sizes and conformations of DL-DNA\nare based on static and 1dynamic light scattering; at the same time, Molecular\nDynamics simulations are employed to model the equilibrium properties of\nDL-DNA, which compare favorably with the findings from experiments while at the\nsame time providing a host of additional information and insight into the\nmolecular structure of the nanostructures. We also examine the\nsalt-responsiveness of these macromolecules, finding that despite the strong\nscreening of electrostatic interactions, brought about by the added salt, the\nmacromolecules shrink only slightly, their size robustness stemming from the\nhigh bending rigidity of the DNA-segments. The study of these charged dendrimer\nsystems is an important field of research in the area of soft matter due to\ntheir potential role for various interdisciplinary applications, ranging from\nmolecular cages and carriers for drug delivery in a living organism to the\ndevelopment of dendrimer- and dendron-based ultra-thin films in the area of\nnanotechnology. These findings are essential to determine if DL-DNA is a viable\ncandidate for the experimental realization of cluster crystals in the bulk, a\nnovel form of solids with multiple site occupancy.",
        "positive": "Particle size effect on strength, failure and shock behavior in\n  Polytetrafluoroethylene-Al-W granular composites: The variation of metallic particle size and sample porosity significantly\nalters the dynamic mechanical properties of high density granular composites\nprocessed using a cold isostatically pressed mixture of polytetrafluoroethylene\n(PTFE), aluminum (Al) and tungsten (W) powders. Quasi-static and dynamic\nexperiments are performed with identical constituent mass fractions with\nvariations in the size of the W particles and pressing conditions. The\nrelatively weak polymer matrix allows the strength and fracture modes of this\nmaterial to be governed by the granular type behavior of agglomerated metal\nparticles. A higher ultimate compressive strength was observed in relatively\nhigh porosity samples with small W particles compared to those with coarse W\nparticles in all experiments. Mesoscale granular force chains comprised of the\nmetallic particles explain this unusual phenomenon as observed in a hydrocode\nsimulation of a drop-weight test. Macrocracks forming below the critical\nfailure strain for the matrix and unusual behavior due to a competition between\ndensification and fracture in dynamic tests of porous samples were also\nobserved. Shock loading of this granular composite resulted in higher fraction\nof total internal energy deposition in the soft PTFE matrix, specifically\nthermal energy, which can be tailored by the W particle size distribution."
    },
    {
        "anchor": "Ballistic Ejection of Microdroplets from Overpacked Interfacial\n  Assemblies: Spontaneous emulsification, resulting from the assembly and accumulation of\nsurfactants at liquid-liquid interfaces, is an interfacial instability where\nmicrodroplets are generated and diffusively spread from the interface until\ncomplete emulsification. Here, we show that an external magnetic field can\nmodulate the assembly of paramagnetic nanoparticle surfactants (NPSs) at\nliquid-liquid interfaces and trigger an oversaturation in the areal density of\nthe NPSs at the interface, as evidenced by a marked reduction in the\ninterfacial tension, {\\gamma}, and corroborated with a magnetostatic continuum\ntheory. Despite the significant reduction in {\\gamma}, the presence of the\nmagnetic field does not cause stable interfaces to become unstable. Upon rapid\nremoval of the field, however, an explosive ejection of a plume of\nmicrodroplets from the surface occurs, a dynamical interfacial instability\nwhich is termed explosive emulsification. This explosive event rapidly reduces\nthe areal density of the NPSs to its pre-field level, stabilizing the\ninterface. The ability to externally suppress or trigger the explosive\nemulsification and controlled generation of tens of thousands of microdroplets,\nuncovers an efficient energy storage and release process, that has potential\napplications for controlled and directed delivery of chemicals and remotely\ncontrolled soft microrobots, taking advantage of the ferromagnetic nature of\nthe microdroplets.",
        "positive": "A microscopically-based, global landscape perspective on slow dynamics\n  in condensed matter: A complete understanding of the precipitous onset of slow dynamics in systems\nsuch as supercooled liquids requires making direct connections between dynamics\nand the underlying potential energy landscape. With the aid of a switch in\nensembles, we show that it is possible to formulate a landscape-based mechanism\nfor the onset of slow dynamics based on the rapid lengthening of the geodesic\npaths that traverse the landscape. We confirm the usefulness of this purely\ngeometric analysis by showing that it successfully predicts the diffusion\nconstants of a standard model supercooled liquid."
    },
    {
        "anchor": "Double-well magnetic trap for Bose-Einstein condensates: We present a magnetic trapping scheme for neutral atoms based on a hybrid of\nIoffe-Pritchard and Time-averaged Orbiting Potential traps. The resulting\ndouble-well magnetic potential has readily controllable barrier height and well\nseparation. This offers a new tool for studying the behavior of Bose\ncondensates in double-well potentials, including atom interferometry and\nJosephson tunneling. We formulate a description for the potential of this\nmagnetic trap and discuss practical issues such as loading with atoms,\nevaporative cooling and manipulating the potential.",
        "positive": "Periodic orbits, pair nucleation, and unbinding of active nematic\n  defects on cones: Geometric confinement and topological constraints present promising means of\ncontrolling active materials. By combining analytical arguments derived from\nthe Born-Oppenheimer approximation with numerical simulations, we investigate\nthe simultaneous impact of confinement together with curvature singularity by\ncharacterizing the dynamics of an active nematic on a cone. Here, the\nBorn-Oppenheimer approximation means that textures can follow defect positions\nrapidly on the time scales of interest. Upon imposing strong anchoring boundary\nconditions at the base of a cone, we find a a rich phase diagram of\nmulti-defect dynamics including exotic periodic orbits of one or two $+1/2$\nflank defects, depending on activity and non-quantized geometric charge at the\ncone apex. By characterizing the transitions between these ordered dynamical\nstates, we can understand (i) defect unbinding, (ii) defect absorption and\n(iii) defect pair nucleation at the apex. Numerical simulations confirm\ntheoretical predictions of not only the nature of the circular orbits but also\ndefect unbinding from the apex."
    },
    {
        "anchor": "Microrheology measurements with a hanging-fiber AFM probe: A method to measure the viscosity of liquids at microscales is presented. It\nuses a thin glass fiber fixed on the tip of the cantilever of an extremely low\nnoise Atomic Force Microscope (AFM), which accurately measures the cantilever\n{deflection}. When the fiber is dipped into the liquid the dissipation of the\ncantilever-fiber system increases. This dissipation, linked to the liquid\nviscosity, is computed from the power spectral density of the thermal\nfluctuations of the cantilever {deflection}. The {high sensitivity of the AFM}\nallows us to show the existence and to develop a model of the coupling between\nthe dynamics of the fiber and that of the cantilever. This model {accurately}\nfits the experimental data. The advantages and draw-backs of the method are\ndiscussed",
        "positive": "Synergistic Energy Absorption Mechanisms of Architected Liquid Crystal\n  Elastomers: Here, we report the rate-dependent energy absorption behavior of a liquid\ncrystal elastomer (LCE)-based architected material consisting of repeating unit\ncells of bistable tilted LCE beams sandwiched between stiff supports.\nViscoelastic behaviors of the LCE material cause the energy absorption to\nincrease with strain rate according to a power-law relationship, which can be\nmodulated by changing the degree of mesogens alignment during synthesis. For a\nstrain rate of 600 s-1, the unit cell structure shows up to a 5 MJ/m3 energy\nabsorption density, which is two orders of magnitude higher than the same\nstructure fabricated from Polydimethylsiloxane (PDMS), and is comparable to the\ndissipation from irreversible plastic deformation exhibited by denser metals.\nFor a stacked structure of unit cells, viscoelasticity also produces nonuniform\nbuckling of the LCE beams, causing the energy absorption density to increase\nwith the stacking number n up to n=3. Varying the beam geometry further\npromotes the nonuniform buckling behavior allowing the energy absorption\ndensity to increase with stacking number without bounds. We envision that our\nstudy can lead to the development of lightweight extreme energy-absorbing\nmaterials."
    },
    {
        "anchor": "Spontaneous Liquid Crystal and Ferromagnetic Ordering of Colloidal\n  Magnetic Nanoplates: Ferrofluids are familiar as colloidal suspensions of ferromagnetic\nnanoparticles in aqueous or organic solvents. The dispersed particles are\nrandomly oriented but their moments become aligned if a magnetic field is\napplied, producing a variety of exotic and useful magneto-mechanical effects. A\nlongstanding interest and challenge has been to make such suspensions\nmacroscopically ferromagnetic, that is having uniform magnetic alignment in\nabsence of a field. Here we report a fluid suspension of magnetic nanoplates\nwhich spontaneously aligns into an equilibrium nematic liquid crystal phase\nthat is also macroscopically ferromagnetic. Its zero-field magnetization\nproduces distinctive magnetic self-interaction effects, including liquid\ncrystal textures of fluid block domains arranged in closed flux loops, and\nmakes this phase highly sensitive, with it dramatically changing shape even in\nthe Earth's magnetic field.",
        "positive": "Formation of bubbly horizon in liquid-saturated porous medium by surface\n  temperature oscillation: We study non-isothermal diffusion transport of a weakly-soluble substance in\na liquid-saturated porous medium being in contact with the reservoir of this\nsubstance. The surface temperature of the porous medium half-space oscillates\nin time, which results in a decaying solubility wave propagating deep into the\nporous medium. In such a system, the zones of saturated solution and\nnon-dissolved phase coexist with the zones of undersaturated solution. The\neffect is firstly considered for the case of annual oscillation of the surface\ntemperature of water-saturated ground being in contact with atmosphere. We\nreveal the phenomenon of formation of a near-surface bubbly horizon due to the\ntemperature oscillation. An analytical theory of the phenomenon is developed.\nFurther, the treatment is extended to the case of higher frequency oscillations\nand case of weakly-soluble solids and liquids."
    },
    {
        "anchor": "Deriving effective mesoscale potentials from atomistic simulations: We demonstrate how an iterative method for potential inversion from\ndistribution functions developed for simple liquid systems can be generalized\nto polymer systems. It uses the differences in the potentials of mean force\nbetween the distribution functions generated from a guessed potential and the\ntrue (simulated) distribution functions to improve the effective potential\nsuccessively. The optimization algorithm is very powerful: convergence is\nreached for every trial function in few iterations. As an extensive test case\nwe coarse-grained an atomistic all-atom model of poly (isoprene) (PI) using a\n13:1 reduction of the degrees of freedom. This procedure was performed for PI\nsolutions as well as for a PI melt. Comparisons of the obtained force fields\nare drawn. They prove that it is not possible to use a single force field for\ndifferent concentration regimes.",
        "positive": "Non-monotonic fluidization generated by fluctuating edge tensions in\n  confluent tissues: In development and homeostasis, multi-cellular systems exhibit spatial and\ntemporal heterogeneity in their biochemical and mechanical properties.\nNevertheless, it remains unclear how spatiotemporally heterogeneous forces\naffect the dynamical and mechanical properties of confluent tissue. To address\nthis question, we study the dynamical behavior of the two-dimensional cellular\nvertex model for epithelial monolayers in the presence of fluctuating cell-cell\ninterfacial tensions, which is a biologically relevant source of mechanical\nspatiotemporal heterogeneity. In particular, we investigate the effects of the\namplitude and persistence time of fluctuating tension on the tissue dynamics.\nWe unexpectedly find that the long-time diffusion constant describing cell\nrearrangements depends non-monotonically on the persistence time, while it\nincreases monotonically as the amplitude increases. Our analysis indicates that\nat low and intermediate persistence times tension fluctuations drive motion of\nvertices and promote cell rearrangements, while at the highest persistence\ntimes the tension in the network evolves so slowly that rearrangements become\nrare."
    },
    {
        "anchor": "DNA-condensation, redissolution and mesocrystals induced by tetravalent\n  counterions: The distance-resolved effective interaction potential between two parallel\nDNA molecules is calculated by computer simulations with explicit tetravalent\ncounterions and monovalent salt. Adding counterions first yields an attractive\nminimum in the potential at short distances which then disappears in favor of a\nshallower minimum at larger separations. The resulting phase diagram includes a\nDNA-condensation and redissolution transition and a stable mesocrystal with an\nintermediate lattice constant for high counterion concentration.",
        "positive": "Roughness Induced Rotational Slowdown Near the Colloidal Glass\n  Transition: Roughening the surface of spherical colloids can drastically change their\ntranslational and rotational dynamics in dense suspensions. Using 3D confocal\nmicroscopy, we show that roughness not only lowers the concentration of the\ntranslational colloidal glass transition, but also generates a broad\nconcentration range in which the rotational Brownian motion changes signature\nfrom high-amplitude diffusive to low-amplitude rattling. This hitherto not\nreported second glass transition for rough spherical colloids emerges when the\nparticle intersurface distance becomes comparable to the roughness length\nscale. Interlocking contacts are responsible for restricting the particle\nrotations."
    },
    {
        "anchor": "Tuning Structure and Rheology of Silica-Latex Nanocomposites with the\n  Molecular Weight of Matrix Chains: A Coupled SAXS-TEM-Simulation Approach: The structure of silica-latex nanocomposites of three matrix chain masses\n(20, 50, and 160 kg/mol of poly(ethyl methacrylate)) are studied using a\nSAXS/TEM approach, coupled via Monte Carlo simulations of scattering of fully\npolydisperse silica nanoparticle aggregates. At low silica concentrations (1\nvol. %), the impact of the matrix chain mass on the structure is quantified in\nterms of the aggregation number distribution function, highest mass leading to\nindividual dispersion, whereas the lower masses favor the formation of small\naggregates. Both simulations for SAXS and TEM give compatible aggregate\ncompacities around 10 vol. %, indicating that the construction algorithm for\naggregates is realistic. Our results on structure are rationalized in terms of\nthe critical collision time between nanoparticles due to diffusion in viscous\nmatrices. At higher concentrations, aggregates overlap and form a percolated\nnetwork, with a smaller and lighter mesh in the presence of high mass polymers.\nThe linear rheology is investigated with oscillatory shear experiments. It\nshows a feature related to the silica structure at low frequencies, the\namplitude of which can be described by two power laws separated by the\npercolation threshold of aggregates.",
        "positive": "Neural functional theory for inhomogeneous fluids: Fundamentals and\n  applications: We present a hybrid scheme based on classical density functional theory and\nmachine learning for determining the equilibrium structure and thermodynamics\nof inhomogeneous fluids. The exact functional map from the density profile to\nthe one-body direct correlation function is represented locally by a deep\nneural network. We substantiate the general framework for the hard sphere fluid\nand use grand canonical Monte Carlo simulation data of systems in randomized\nexternal environments during training and as reference. Functional calculus is\nimplemented on the basis of the neural network to access higher-order\ncorrelation functions via automatic differentiation and the free energy via\nfunctional line integration. Thermal Noether sum rules are validated\nexplicitly. We demonstrate the use of the neural functional in the\nself-consistent calculation of density profiles. The results outperform those\nfrom state-of-the-art fundamental measure density functional theory. The low\ncost of solving an associated Euler-Lagrange equation allows to bridge the gap\nfrom the system size of the original training data to macroscopic predictions\nupon maintaining near-simulation microscopic precision. These results establish\nthe machine learning of functionals as an effective tool in the multiscale\ndescription of soft matter."
    },
    {
        "anchor": "Glass elasticity from particle trajectories: Using positional data from video-microscopy of a two-dimensional colloidal\nsystem and from simulations of hard discs we determine the\nwave-vector-dependent normal mode spring constants in the supercooled fluid and\nglassy state, respectively. The emergence of rigidity and the existence of a\ndisplacement field in amorphous solids is clarified. Continuum elastic theory\nis used in the limit of long wavelengths to analyze the bulk and shear modulus\nof this amorphous system as a function of temperature. The onset of a finite\nstatic shear modulus upon cooling marks the fluid/solid transition. This\nprovides an opportunity to determine the glass transition temperature $T_g$ in\nan intuitive and precise way.",
        "positive": "Influence of Dopamine Methacrylamide on swelling behaviour and\n  nanomechanical properties of PNIPAM microgels: The combination of the catechol-containing co-monomer dopamine methacrylamide\n(DMA) with stimuli-responsive microgels such as poly(N-isopropylacrylamide)\n(PNIPAM) bears a huge potential in research and for applications due to the\nversatile properties of catechols. This research gives first detailed insights\ninto the influence of DMA on the swelling of PNIPAM microgels and the\ncorrelation with their nanomechanical properties. Dynamic light scattering\n(DLS) was used to analyse the swelling behaviour of microgels in bulk solution.\nThe incorporation of DMA decreases the volume phase transition temperature\n(VPTT) and completion temperature (VPT CT) due to its higher hydrophobicity\nwhen compared to NIPAM, while sharpening the transition. The cross-linking\nability of DMA decreases swelling ratios and mesh sizes of the microgels.\nMicrogels adsorbed at the solid surface are characterised by atomic force\nmicroscopy (AFM): Scanning provides information about the microgel's shape on\nthe surface and force spectroscopy measurements determines their nanomechanical\nproperties ($E$ modulus). As the DMA content increases, microgels protrude more\nfrom the surface, correlating with an increase of $E$ modulus and a stiffening\nof the microgels - confirming the cross-linking ability of DMA. Force\nspectroscopy measurements below and above the VPTT display a stiffening of the\nmicrogels with the incorporation of DMA and upon heating across it's entire\ncross-section. The affine network factor $\\beta$, derived from the Flory-Rehner\ntheory describing the elasticity and swelling of the microgel network, is\nlinearly correlated with the $E$ moduli of the microgels for both - pure PNIPAM\nand P(NIPAM-co-DMA) microgels. However, for large amounts of DMA, DMA appears\nto hinder the microgel shrinking, while still ensuring mechanical stiffness,\npossibly due to catechol interactions within the microgel network."
    },
    {
        "anchor": "Topological Transformations in Hyperuniform Pentagonal 2D Materials\n  Induced by Stone-Wales Defects: We discover two distinct topological pathways through which the pentagonal\nCairo tiling (P5), a structural model for single-layer $AB_2$ pyrite materials,\nrespectively transforms into a crystalline rhombus-hexagon (C46) tiling and\nrandom rhombus-pentagon-hexagon (R456) tilings, by continuously introducing the\nStone-Wales (SW) topological defects. We find these topological transformations\nare controlled by the orientation correlations among neighboring $B$-$B$ bonds,\nand exhibit a phenomenological analogy of the (anti)ferromagnetic to\nparamagnetic transition in two-state Ising systems. Unlike the SW defects in\nhexagonal 2D materials such as graphene, which cause distortions, the defects\nin pentagonal 2D materials preserve the shape and symmetry of the fundamental\ncell of P5 tiling and are associated with a minimal energy cost, making the\nintermediate R456 tilings realizable metastable states at room temperature.\nMoreover, the intermediate structures along the two pathways are neither\ncrystals nor quasicrystals, and yet these random tilings preserve\nhyperuniformity of the P5 or C46 crystal (i.e., the infinite-wavelength\nnormalized density fluctuations are completely suppressed), and can be viewed\nas 2D analogs of disordered Barlow packings in three dimensions. The resulting\n2D materials possess metal-like electronic properties, making them promising\ncandidates for forming Schottky barriers with the semiconducting P5 material.",
        "positive": "Modelling the evaporation of thin films of colloidal suspensions using\n  Dynamical Density Functional Theory: Recent experiments have shown that various structures may be formed during\nthe evaporative dewetting of thin films of colloidal suspensions. Nano-particle\ndeposits of strongly branched `flower-like', labyrinthine and network\nstructures are observed. They are caused by the different transport processes\nand the rich phase behaviour of the system. We develop a model for the system,\nbased on a dynamical density functional theory, which reproduces these\nstructures. The model is employed to determine the influences of the solvent\nevaporation and of the diffusion of the colloidal particles and of the liquid\nover the surface. Finally, we investigate the conditions needed for\n`liquid-particle' phase separation to occur and discuss its effect on the\nself-organised nano-structures."
    },
    {
        "anchor": "Temperature dependence of the hydrogen bond network in Trimethylamine\n  N-oxide and guanidine hydrochloride - water solutions: We present an X-ray Compton scattering study on aqueous Trimethylamine\nN-oxide (TMAO) and guanidine hydrochloride solutions (GdnHCl) as a function of\ntemperature. Independent from the concentration of the solvent, Compton\nprofiles almost resemble results for liquid water as a function of temperature.\nHowever, The number of hydrogen bonds per water molecule extracted from the\nCompton profiles suggests a decrease of hydrogen bonds with rising temperatures\nfor all studied samples, the differences between water and the solutions are\nweak. Nevertheless, the data indicate a reduced bond weakening with rising TMAO\nconcentration up to 5M of 7.2% compared to 8 % for pure water. In contrast, the\naddition of GdnHCl appears to behave differently for concentrations up to 3.1 M\nwith a weaker impact on the temperature response of the hydrogen bond\nstructure.",
        "positive": "The vortex-driven dynamics of droplets within droplets: Understanding the fluid-structure interaction is crucial for an optimal\ndesign and manufacturing of soft mesoscale materials. Multi-core emulsions are\na class of soft fluids assembled from cluster configurations of deformable\noil-water double droplets (cores), often employed as building-blocks for the\nrealisation of devices of interest in bio-technology, such as drug-delivery,\ntissue engineering and regenerative medicine. Here, we study the physics of\nmulti-core emulsions flowing in microfluidic channels and report numerical\nevidence of a surprisingly rich variety of driven non-equilibrium states (NES),\nwhose formation is caused by a dipolar fluid vortex triggered by the sheared\nstructure of the flow carrier within the microchannel. The observed dynamic\nregimes range from long-lived NES at low core-area fraction, characterised by a\nplanetary-like motion of the internal drops, to short-lived ones at high\ncore-area fraction, in which a pre-chaotic motion results from multi-body\ncollisions of inner drops, as combined with self-consistent hydrodynamic\ninteractions. The onset of pre-chaotic behavior is marked by transitions of the\ncores from one vortex to another, a process that we interpret as manifestations\nof the system to maximize its entropy by filling voids, as they arise\ndynamically within the capsule."
    },
    {
        "anchor": "Stochastic Eulerian-Lagrangian Methods for Fluid-Structure Interactions\n  with Thermal Fluctuations and Shear Boundary Conditions: A computational approach is introduced for the study of the rheological\nproperties of complex fluids and soft materials. The approach allows for a\nconsistent treatment of microstructure elastic mechanics, hydrodynamic\ncoupling, thermal fluctuations, and externally driven shear flows. A mixed\ndescription in terms of Eulerian and Lagrangian reference frames is used for\nthe physical system. Microstructure configurations are represented in a\nLagrangian reference frame. Conserved quantities, such as momentum of the fluid\nand microstructures, are represented in an Eulerian reference frame. The\nmathematical formalism couples these different descriptions using general\noperators subject to consistency conditions. Thermal fluctuations are taken\ninto account in the formalism by stochastic driving fields introduced in\naccordance with the principles of statistical mechanics. To study the\nrheological responses of materials subject to shear, generalized periodic\nboundary conditions are developed where periodic images are shifted relative to\nthe unit cell to induce shear. Stochastic numerical methods are developed for\nthe formalism. As a demonstration of the methods, results are presented for the\nshear responses of a polymeric fluid, lipid vesicle fluid, and a gel-like\nmaterial.",
        "positive": "Measure of distance and overlap between two arbitrary ellipses on a\n  sphere: Various packing problems and simulations of hard and soft interacting\nparticles, such as microscopic models of nematic liquid crystals, reduce to\ncalculations of intersections and pair interactions between ellipsoids. When\nconstrained to a spherical surface, curvature and compactness lead to\nnontrivial behavior that finds uses in physics, computer science and geometry.\nA well-known idealized isotropic example is the Tammes problem of finding\noptimal non-intersecting packings of equal hard disks. The anisotropic case of\nelliptic particles remains, on the other hand, comparatively unexplored. We\ndevelop an algorithm to detect collisions between ellipses constrained to the\ntwo-dimensional surface of a sphere based on a solution of an eigenvalue\nproblem. We investigate and discuss topologically distinct ways two ellipses\nmay touch or intersect on a sphere, and define a contact function that can be\nused for construction of short- and long-range pair potentials."
    },
    {
        "anchor": "A constant extension ensembles model of double-stranded chain molecules: Because the constant extension ensemble of single chain molecule is not\nalways equivalent with constant force ensemble, a model of double-stranded\nconformations, as in RNA molecules and $\\beta$-sheets in proteins, with fixed\nextension constraint is built in this paper. Based on polymer-graph theory and\nthe self-avoiding walks, sequence dependence and excluded-volume interactions\nare explicitly taken into account. Using the model, we investigate\nforce-extension curves, contact distributions and force-temperature curves at\ngiven extensions. We find that, for the same homogeneous chains, the\nforce-extension curves are almost consistent with the extension-force curves in\nthe conjugated force ensembles. Especially, the consistence depends on chain\nlengths. But the curves of the two ensembles are completely different from each\nother if sequences are considered. In addition, contact distributions of\nhomogeneous sequence show that the double-stranded regions in hairpin\nconformations tend to locate at two sides of the chain. We contribute the\nunexpected phenomena to the nonuniformity of excluded-volume interactions of\nthe region and two tails with different lengths. This tendency will disappear\nif the interactions are canceled. Finally, in constant extension ensemble, the\nforce-flipping transitions conjugated with re-entering phenomena in constant\nforce ensemble are observed in hairpin conformations, while they do not present\nin secondary structure conformations.",
        "positive": "Skyrmion Tubes in achiral nematic liquid crystals: We analyze the interaction with uniform external fields of nematic liquid\ncrystals within a recent generalized free-energy posited by Virga and falling\nin the class of quartic functionals in the spatial gradients of the nematic\ndirector. We review some known interesting solutions, i. e., uniform\nheliconical structures, which correspond to the so-called twist-bend nematic\nphase and we also study the transition between this phase and the standard\nuniform nematic one. Moreover, we find liquid crystal configurations, which\nclosely resemble some novel, experimentally detected, structures called\nSkyrmion Tubes. Skyrmion Tubes are characterized by a localized\ncylindrically-symmetric pattern surrounded by either twist-bend or uniform\nnematic phase. We study the equilibrium differential equations and find\nnumerical solutions and analytical approximations."
    },
    {
        "anchor": "Tracer diffusion in a sea of polymers with binding zones: mobile vs\n  frozen traps: We use molecular dynamics simulations to investigate the tracer diffusion in\na sea of polymers with specific binding zones for the tracer. These binding\nzones act as traps. Our simulations show that the tracer can undergo normal yet\nnon-Gaussian diffusion under certain circumstances, e.g, when the polymers with\ntraps are frozen in space and the volume fraction and the binding strength of\nthe traps are moderate. In this case, as the tracer moves, it experiences a\nheterogeneous environment and exhibits confined continuous time random walk\n(CTRW) like motion resulting a non-Gaussian behavior. Also the long time\ndynamics becomes subdiffusive as the number or the binding strength of the\ntraps increases. However, if the polymers are mobile then the tracer dynamics\nis Gaussian but could be normal or subdiffusive depending on the number and the\nbinding strength of the traps. In addition, with increasing binding strength\nand the number of the polymer traps, the probability of the tracer being\ntrapped increases. On the other hand, removing the binding zones does not\nresult trapping, even at comparatively high crowding. Our simulations also show\nthat the trapping probability increases with the increasing size of the tracer\nand for a bigger tracer with the frozen polymer background the dynamics is only\nweakly non-Gaussian but highly subdiffusive. Our observations are in the same\nspirit as found in many recent experiments on tracer diffusion in polymeric\nmaterials and questions the validity of Gaussian theory to describe diffusion\nin crowded environment in general.",
        "positive": "Spontaneous morphing of equibiaxially pre-stretched elastic bilayers:\n  the role of sample geometry: An elastic bilayer, consisting of an equibiaxially pre-stretched sheet bonded\nto a stress-free one, spontaneously morphs into curved shapes in the absence of\nexternal loads or constraints. Using experiments and numerical simulations, we\nexplore the role of geometry for square and rectangular samples in determining\nthe equilibrium shape of the system, for a fixed pre-stretch. We classify the\nobserved shapes over a wide range of aspect ratios according to their\ncurvatures and compare measured and computed values, which show good agreement.\nIn particular, as the bilayer becomes thinner, a bifurcation of the principal\ncurvatures occurs, which separates two scaling regimes for the energy of the\nsystem. We characterize the transition between these two regimes and show the\npeculiar features that distinguish square from rectangular samples. The results\nfor our model bilayer system may help explaining morphing in more complex\nsystems made of active materials."
    },
    {
        "anchor": "Experimental observation of the marginal glass phase in a colloidal\n  glass: The replica theory of glasses predicts that in the infinite dimensional mean\nfield limit there exist two distinct glassy phases of matter: stable glass and\nmarginal glass. We have developed a technique to experimentally probe these\nphases of matter using a colloidal glass. We avoid the difficulties inherent in\nmeasuring the long time behavior of glasses by instead focusing on the very\nshort time dynamics of the ballistic to caged transition. We track a single\ntracer particle within a slowly densifying glass and measure the resulting mean\nsquared displacement (MSD). By analyzing the MSD we find that upon\ndensification our colloidal system moves through several states of matter. At\nlowest densities it is a sub-diffusive liquid. Next it behaves as a stable\nglass, marked by the appearance of a plateau in the MSD whose magnitude shrinks\nwith increasing density. However, this shrinking plateau does not shrink to\nzero, instead at higher densities the system behaves as a marginal glass,\nmarked by logarithmic growth in the MSD towards that previous plateau value.\nFinally, at the highest experimental densities the system returns to the stable\nglass phase. This provides direct experimental evidence for the existence of a\nmarginal glass in 3d.",
        "positive": "Continuous manipulation and characterization of colloidal beads and\n  liposomes via diffusiophoresis in single- and double-junction microchannels: We reveal an unreported physical mechanism that enables the\npre-concentration, sorting and characterization of charged polystyrene\nnanobeads and liposomes dispersed in a continuous flow within a straight\nmicron-sized channel. Initially, a single $\\Psi$-junction microfluidic chip is\nused to generate a steady-state salt concentration gradient in the direction\nperpendicular to the flow. As a result, fluorescent nanobeas dispersed in the\nelectrolyte solutions accumulate into symmetric regions of the channel,\nappearing as two distinct symmetric stripes when the channel is observed from\ntop via epi-fluorescence microscopy. Depending on the electrolyte flow\nconfiguration and, thus, the direction of the salt gradient field, the\nfluorescent stripes get closer to or apart from each other as the distance from\nthe inlet increases. Our numerical and experimental analysis shows that,\nalthough diffusiophoresis and hydrodynamic effects are involved in the\naccumulation process, diffusioosmosis plays a crucial role in the observed\nparticles dynamics. In addition, we developed a proof-of-concept double\n$\\Psi$-junction microfluidic device which exploits this new accumulation\nmechanism for the size-based separation and size detection of nanobeads as well\nas for the measurement of zeta potential and charged lipid composition of\nliposomes under continuous flow settings. This device is also used to\ninvestigate the effect of fluid-like or gel-like states of the lipid membranes\non the liposome diffusiophoretic response. The proposed strategies for\nsolute-driven manipulation of colloids have great potential for microfluidic\nbio-analytical testing applications, including bioparticle pre-concentration,\nsorting, sensing and analysis."
    },
    {
        "anchor": "Amorphous Solidification of a Supercooled Liquid in the Limit of Rapid\n  Cooling: We monitor the transformation of a liquid into an amorphous solid in\nsimulations of a glass forming liquid by measuring the variation of a\nstructural order parameter with either changing temperature or potential energy\nto establish the influence of the cooling rate on amorphous solidification. We\nshow that the latter representation, unlike the former, exhibits no significant\ndependence on cooling rate. This independence extends to the limit of\ninstantaneous quenches which we find can accurately reproduce the\nsolidification observed during slow cooling. We conclude that amorphous\nsolidification is an expression of the topography of the energy landscape and\npresent the relevant topographic measures.",
        "positive": "Coarsening and mechanics in the bubble model for wet foams: Aqueous foams are an important model system that displays coarsening\ndynamics. Coarsening in dispersions and foams is well understood in the dilute\nand dry limits, where the gas fraction tends to zero and one, respectively.\nHowever, foams are known to undergo a jamming transition from a fluid-like to a\nsolid-like state at an intermediate gas fraction,$\\phi_c$. Much less is known\nabout coarsening dynamics in wet foams near jamming, and the link to mechanical\nresponse, if any, remains poorly understood. Here, we probe coarsening and\nmechanical response using numerical simulations of a variant of the Durian\nbubble model for wet foams. As in other coarsening systems we find a steady\nstate scaling regime with an associated particle size distribution. We relate\nthe time-rate of evolution of the coarsening process to the wetness of the foam\nand identify a characteristic coarsening time that diverges approaching\njamming. We further probe mechanical response of the system to strain while\nundergoing coarsening. There are two competing time scales, namely the\ncoarsening time and the mechanical relaxation time. We relate these to the\nevolution of the elastic response and the mechanical structure."
    },
    {
        "anchor": "Premicellar aggregation of amphiphilic molecules: Aggregate lifetime and\n  polydispersity: A recently introduced thermodynamic model of amphiphilic molecules in\nsolution has yielded, under certain realistic conditions, a significant\npresence of metastable aggregates well below the critical micelle concentration\n-- a phenomenon that has been reported also experimentally. The theory is\nextended in two directions pertaining to the experimental and technological\nrelevance of such premicellar aggregates. (a) Combining the thermodynamic model\nwith reaction rate theory, we calculate the lifetime of the metastable\naggregates. (b) Aggregation number fluctuations are examined. We demonstrate\nthat, over most of the metastable concentration range, the premicellar\naggregates should have macroscopic lifetimes and small polydispersity.",
        "positive": "Quasi-static incremental behavior of granular materials: elastic-plastic\n  coupling and micro-scale dissipation: The paper addresses a common assumption of elastoplastic modeling: that the\nrecoverable, elastic strain increment is unaffected by alterations of the\nelastic moduli that accompany loading. This assumption is found to be false for\na granular material, and discrete element (DEM) simulations demonstrate that\ngranular materials are coupled materials at both micro- and macro-scales.\nElasto-plastic coupling at the macro-scale is placed in the context of\nthermomechanics framework of Tomasz Hueckel and Hans Ziegler, in which the\nelastic moduli are altered by irreversible processes during loading. This\ncomplex behavior is explored for multi-directional loading probes that follow\nan initial monotonic loading. An advanced DEM model is used in the study, with\nnon-convex non-spherical particles and two different contact models: a\nconventional linear-frictional model and an exact implementation of the\nHertz-like Cattaneo-Mindlin model. Rectilinear true-triaxial probes were used\nin the study (i.e., no direct shear strain), with tiny strain increments of\n$2\\times 10^{-6}$. At the micro-scale, contact movements were monitored during\nsmall increments of loading and load-reversal, and results show that these\nmovements are not reversed by a reversal of strain direction, and some contacts\nthat were sliding during a loading increment continue to slide during reversal.\nThe probes show that the coupled part of a strain increment, the difference\nbetween the recoverable (elastic) increment and its reversible part, must be\nconsidered when partitioning strain increments into elastic and plastic parts.\nSmall increments of irreversible (and plastic) strain and contact slipping and\nfrictional dissipation occur for all directions of loading, and an elastic\ndomain, if it exists at all, is smaller than the strain increment used in the\nsimulations."
    },
    {
        "anchor": "Counter-ion release and electrostatic adsorption: The effective charge of a rigid polyelectrolyte (PE) approaching an\noppositely charged surface is studied. The cases of a weak (annealed) and\nstrongly charged PE with condensed counterions (such as DNA) are discussed. In\nthe most interesting case of the adsorption onto a substrate of low dielectric\nconstant (such as a lipid membrane or a mica sheet) the condensed counterions\nare not always released as the PE approaches the substrate, because of the\nmajor importance of the image charge effect. For the adsorption onto a surface\nwith freely moving charges, the image charge effect becomes less important and\nfull release is often expected.",
        "positive": "Predicting the Characteristics of Defect Transitions on Curved Surfaces: The energetically optimal position of lattice defects on intrinsically curved\nsurfaces is a complex function of shape parameters. For open surfaces, a simple\ncondition predicts the critical size for which a central disclination yields\nlower energy than a boundary disclination. In practice, this transition is\nmodified by activation energies or more favorable intermediate defect\npositions. Here it is shown that these transition characteristics (continuous\nor discontinuous, first or second order) can also be inferred from analytical,\ngeneral criteria evaluated from the surface shape. A universal scale of\nactivation energy is found, and the criterion is generalized to predict\ntransition order as symmetries such as that of the shape are broken. The\nresults give practical insight into structural transitions to disorder in many\ncellular materials of technological and biological importance."
    },
    {
        "anchor": "Colloidal dipolar interactions in 2D smectic C films: We use a two-dimensional (2D) elastic free energy to calculate the effective\ninteraction between two circular disks immersed in smectic-$C$ films. For\nstrong homeotropic anchoring, the distortion of the director field caused by\nthe disks generates additional topological defects that induce an effective\ninteraction between the disks. We use finite elements, with adaptive meshing,\nto minimize the 2D elastic free energy. The method is shown to be accurate and\nefficient for inhomogeneities on the length scales set by the disks and the\ndefects, that differ by up to 3 orders of magnitude. We compute the effective\ninteraction between two disk-defect pairs in a simple (linear) configuration.\nFor large disk separations, $D$, the elastic free energy scales as $\\sim\nD^{-2}$, confirming the dipolar character of the long-range effective\ninteraction. For small $D$ the energy exhibits a pronounced minimum. The lowest\nenergy corresponds to a symmetrical configuration of the disk-deffect pairs,\nwith the inner defect at the mid-point between the disks. The disks are\nseparated by a distance that is twice the distance of the outer defect from the\nnearest disk. The latter is identical to the equilibrium distance of a defect\nnucleated by an isolated disk.",
        "positive": "Dynamics in dense hard-sphere colloidal suspensions: The dynamic behavior of a hard-sphere colloidal suspension was studied by\nX-ray Photon Correlation Spectroscopy and Small Angle X-ray Scattering over a\nwide range of particle volume fractions. The short-time mobility of the\nparticles was found to be smaller than that of free particles even at\nrelatively low concentrations, showing the importance of indirect hydrodynamic\ninteractions. Hydrodynamic functions were derived from the data and for\nmoderate particle volume fractions (> 0.40) there is a good agreement with\nearlier many-body theory calculations by Beenakker and Mazur [C.W.J. Beenakker\nand P. Mazur, Physica A 120, 349 (1984)]. Important discrepancies appear at\nhigher concentrations, above ~0.40, where the hydrodynamic effects are\noverestimated by the Beenakker-Mazur theory, but predicted accurately by an\naccelerated Stokesian dynamics algorithm developed by Banchio and Brady [A.J.\nBanchio and J. F. Brady, J. Chem. Phys. 118, 10323 (2003)]. For the relaxation\nrates, good agreement was also found between the experimental data and a\nscaling form predicted by Mode Coupling Theory. In the high concentration\nrange, with the fluid suspensions approaching the glass transition, the\nlong-time diffusion coefficient was compared with the short-time collective\ndiffusion coefficient to verify a scaling relation previously proposed by Segre\nand Pusey [P.N. Segre and P.N. Pusey, Phys. Rev. Lett. 77, 771 (1996)]. We\ndiscuss our results in view of previous experimental attempts to validate this\nscaling law [L. Lurio et al., Phys. Rev. Lett. 84, 785 (2000)]"
    },
    {
        "anchor": "Jamming is a first-order transition with quenched disorder in amorphous\n  materials sheared by cyclic quasistatic deformations: Jamming is an athermal transition between flowing and rigid states in\namorphous systems such as granular matter, colloidal suspensions, complex\nfluids and cells. The jamming transition seems to display mixed aspects of a\nfirst-order transition, evidenced by a discontinuity in the coordination\nnumber, and a second-order transition, indicated by power-law scalings and\ndiverging lengths. Here we demonstrate that jamming is a first-order transition\nwith quenched disorder in cyclically sheared systems with quasistatic\ndeformations. Particle models are simulated in two and three dimensions, which\nundergo reversible-irreversible transitions under cyclic shear. The ensemble of\nconfigurations, with partially crystallized and fragile states excluded, is\ngenerated in the irreversible phase, where the system is stationary and\nparticles are diffusive. Detailed scaling analyses are performed on the\ndistribution of coordination numbers. The fluctuation of the jamming density in\nfinite-sized systems has important consequences on the finite-size effects of\nvarious quantities, resulting in a square relationship between disconnected and\nconnected susceptibilities, a key signature of first-order transitions with\nquenched disorder. This study puts the jamming transition into the category of\na broad class of transitions in disordered systems, including the first-order\ntransition in the random-field Ising model, brittle yielding of amorphous\nmaterials, and melting of ultra-stable glasses.",
        "positive": "Computer simulation study of a mesogenic lattice model based on\n  long-range dispersion interactions: In contrast to thermotropic biaxial nematic phases, for which some long\nsought for experimental realizations have been obtained, no experimental\nrealizations are yet known for their tetrahedratic and cubatic\ncounterparts,involving orientational orders of ranks 3 and 4, respectively,\nalso studied theoretically over the last few decades. In previous studies,\ncubatic order has been found for hard-core or continuous models consisting of\nparticles possessing cubic or nearly-cubic tetragonal or orthorhombic\nsymmetries; in a few cases, hard-core models involving uniaxial ($D_{\\infty\nh}-$symmetric) particles have been claimed to produce cubatic order as well.\nHere we address by Monte Carlo simulation a lattice model consisting of\nuniaxial particles coupled by long-range dispersion interactions of the\nLondon-De Boer-Heller type; the model was found to produce no second-rank\nnematic but only fourth-rank cubatic order, in contrast to the nematic behavior\nlong known for its counterpart with interactions truncated at nearest-neighbor\nseparation."
    },
    {
        "anchor": "Change in flexibility of DNA with binding ligands: The percentage and sequence of AT and GC base pairs and charges on the DNA\nbackbone contribute significantly to the stiffness of DNA. This elastic\nproperty of DNA also changes with small interacting ligands. The\nsingle-molecule force spectroscopy technique shows different interaction modes\nby measuring the mechanical properties of DNA bound with small ligands. When a\nds-DNA molecule is overstretched in the presence of ligands, it undergoes a\nco-operative structural transition based on the externally applied force, the\nmode of binding of the ligands, the binding constant of the ligands to the DNA,\nthe concentration of the ligands and the ionic strength of the supporting\nmedium. This leads to the changes in the regions- upto 60 pN, cooperative\nstructural transition region and the overstretched region, compared to that of\nthe FEC in the absence of any binding ligand. The cooperative structural\ntransitions were studied by the extended and twistable worm-like chain model.\nHere we have depicted these changes in persistence length and the elastic\nmodulus constant as a function of binding constant and the concentration of the\nbound ligands, which vary with time. Therefore, besides ionic strength,\ninteracting proteins and content of AT and GC base pairs, the ligand binding or\nintercalation with the ligands is an important parameter which changes the\nstiffness of DNA.",
        "positive": "Generation of mechanical force by grafted polyelectrolytes in an\n  electric field. Application to polyelectrolyte-based nano-devices: We analyze theoretically and by means of molecular dynamics (MD) simulations\nthe generation of mechanical force by a polyelectrolyte (PE) chain grafted to a\nplane. The PE is exposed to an external electric field that favors its\nadsorption on the plane. The free end of the chain is linked to a deformable\ntarget body. Varying the field one can alter the length of the non-adsorbed\npart of the chain. This entails variation of the deformation of the target body\nand hence variation of the arising in the body force. Our theoretical\npredictions for the generated force are in a very good agreement with the MD\ndata. Using the developed theory for the generated force we study the\neffectiveness of possible PE-based nano-vices, comprised of two clenching\nplanes connected by PEs and exposed to an external electric field. We exploit\nCundall-Struck solid friction model to describe the friction between a particle\nand the clenching planes. We compute the self-diffusion coefficient of a\nclenched particle and show that it drastically decreases even in weak applied\nfields. This demonstrates the efficacy of the PE-based nano-vices, which may be\na a possible alternative to the existing nano-tube nano-tweezers and optical\ntweezers."
    },
    {
        "anchor": "Manifestations of metastable criticality in the long-range structure of\n  model water glasses: Much attention has been devoted to water's metastable phase behavior,\nincluding polyamorphism (multiple amorphous solid phases), and the hypothesized\nliquid-liquid transition and associated critical point. However, the possible\nrelationship between these phenomena remains incompletely understood. Using\nmolecular dynamics simulations of the realistic TIP4P/2005 model, we found a\nstriking signature of the liquid-liquid critical point in the structure of\nwater glasses, manifested as a pronounced increase in long-range density\nfluctuations at pressures proximate to the critical pressure. By contrast,\nthese signatures were absent in glasses of two model systems that lack a\ncritical point. We also characterized the departure from equilibrium upon\nvitrification via the non-equilibrium index; water-like systems exhibited a\nstrong pressure dependence in this metric, whereas simple liquids did not.\nThese results reflect a surprising relationship between the metastable\nequilibrium phenomenon of liquid-liquid criticality and the non-equilibrium\nstructure of glassy water, with implications for our understanding of water\nphase behavior and glass physics. Our calculations suggest a possible\nexperimental route to probing the existence of the liquid-liquid transition in\nwater and other fluids.",
        "positive": "Intermolecular Cross-Correlations in the Dielectric Response of Glycerol: We suggest a way to disentangle self- from cross-correlation contributions in\nthe dielectric spectra of glycerol. Recently it was demonstrated for\nmonohydroxy alcohols that a detailed comparison of the dynamic susceptibilities\nof photon correlation and broadband dielectric spectroscopy allows to\nunambiguously disentangle a collective relaxation mode known as the Debye\nprocess, which could arises due to supramolecular structures, and the\n$\\alpha$-relaxation, which proves to be identical in both methods. In the\npresent paper, we apply the same idea and analysis to the paradigmatic glass\nformer glycerol. For that purpose we present new light scattering data from\nphoton correlation spectroscopy measurements and combine these with literature\ndata to obtain a data set covering a dynamic range from $10^{-4}-10^{13}\\,$Hz.\nThen we apply the above mentioned analysis by comparing this data set with a\ncorresponding set of broadband dielectric data. Our finding is that even in a\npolyalcohol self- and cross-correlation contributions can approximately be\ndisentangled in that way and that the emerging picture is very similar to that\nin monohydroxy alcohols. This is further supported by comparing the data with\nfast field cycling NMR measurements and dynamic shear relaxation data from the\nliterature, and it turns out that, within the described approach, the\n$\\alpha$-process appears very similar in all methods, while the pronounced\ndifferences observed in the spectral density are due to a different expression\nof the slow collective relaxational contribution. In the dielectric spectra the\nstrength of this peak is reasonably well estimated by the Kirkwood correlation\nfactor, which supports the view that it arises due to dynamic\ncross-correlations, which were previously often assumed to be negligible in\ndielectric measurements."
    },
    {
        "anchor": "Derivation of a constitutive model for the rheology of jammed soft\n  suspensions from particle dynamics: Considering the rheology of two-dimensional soft suspensions above the\njamming density, we derive a tensorial constitutive model from the microscopic\nparticle dynamics. Starting from the equation governing the $N$-particle\ndistribution, we derive an evolution equation for the stress tensor. This\nevolution equation is not closed, as it involves the pair and three-particle\ncorrelation functions. To close this equation, we first employ the standard\nKirkwood closure relation to express the three-particle correlation function in\nterms of the pair correlation function. Then we use a simple and physically\nmotivated parametrization of the pair correlation function to obtain a closed\nevolution equation for the stress tensor. The latter is naturally expressed as\nseparate evolution equations for the pressure and for the deviatoric part of\nthe stress tensor. These evolution equations provide us with a non-linear\ntensorial constitutive model describing the rheological response of a jammed\nsoft suspension to an arbitrary uniform deformation. One of the advantages of\nthis microscopically-rooted description is that the coefficients appearing in\nthe constitutive model are known in terms of packing fraction and microscopic\nparameters.",
        "positive": "Single-File diffusion in a Box: We study diffusion of (fluorescently) tagged hard-core interacting particles\nof finite size in a finite one-dimensional system. We find an exact analytical\nexpression for the tagged particle probability density using a coordinate\nBethe-ansatz, from which the mean square displacement is calculated. The\nanalysis show the existence of three regimes of drastically different behavior\nfor short, intermediate and large times. The results show excellent agreement\nwith stochastic simulations (Gillespie algorithm). The findings of the Letter\nholds promise for the development of novel bio-nano sensors."
    },
    {
        "anchor": "Dynamics of Lieb-Liniger Gases: It is proved that the Lieb-Liniger (LL) cusp condition implementing the delta\nfunction interaction in one-dimensional Bose gases is dynamically conserved\nunder phase imprinting by pulses of arbitrary spatial form and the subsequent\nmany-body dynamics in the thermodynamic limit is expressed approximately in\nterms of solutions of the time-dependent single-particle Schrodinger equation\nfor a set of time-dependent orbitals evolving from an initial LL-Fermi sea. As\nan illustrative application, generation of gray solitons in a LL gas on a ring\nby a phase-imprinting pulse is studied.",
        "positive": "The no-slip condition for a mixture of two liquids: When a mixture of two viscous liquids flows past a solid wall there is an\nambiguity in the use of the no-slip boundary condition. It is not obvious\nwhether the mass-averaged velocity, the volume-averaged velocity, the\nindividual species velocities, all or none of the above, or none of the above\nshould exhibit no-slip. Extensive molecular dynamics simulations of the\nPoiseuille flow of mixtures of coexisting liquid species past an atomistic wall\nindicate that the velocity of each individual liquid species satisfies the\nno-slip condition and, therefore, so do mass and volume averages."
    },
    {
        "anchor": "Machine Learning in a data-limited regime: Augmenting experiments with\n  synthetic data uncovers order in crumpled sheets: Machine learning has gained widespread attention as a powerful tool to\nidentify structure in complex, high-dimensional data. However, these techniques\nare ostensibly inapplicable for experimental systems where data is scarce or\nexpensive to obtain. Here we introduce a strategy to resolve this impasse by\naugmenting the experimental dataset with synthetically generated data of a much\nsimpler sister system. Specifically, we study spontaneously emerging local\norder in crease networks of crumpled thin sheets, a paradigmatic example of\nspatial complexity, and show that machine learning techniques can be effective\neven in a data-limited regime. This is achieved by augmenting the scarce\nexperimental dataset with inexhaustible amounts of simulated data of rigid\nflat-folded sheets, which are simple to simulate and share common statistical\nproperties. This significantly improves the predictive power in a test problem\nof pattern completion and demonstrates the usefulness of machine learning in\nbench-top experiments where data is good but scarce.",
        "positive": "Critical polymer-polymer phase separation in ternary solutions: We study polymer-polymer phase separation in a common good solvent by means\nof Monte Carlo simulations of the bond-fluctuation model. Below a critical,\nchain-length dependent concentration, no phase separation occurs. For higher\nconcentrations, the critical demixing temperature scales nonlinearly with the\ntotal monomer concentration, with a power law relatively close to a\nrenormalization-group prediction based on \"blob\" scaling arguments. We point\nout that earlier simulations and experiments have tested this power-law\ndependence at concentrations outside the validity regime of the scaling\narguments. The critical amplitudes of the order parameter and the zero-angle\nscattering intensity also exhibit chain-length dependences that differ from the\nconventional predictions but are in excellent agreement with the\nrenormalization-group results. In addition, we characterize the variation of\nthe average coil shape upon phase separation."
    },
    {
        "anchor": "Drop deposition on surfaces with contact-angle hysteresis: Liquid-bridge\n  stability and breakup: We study the stability and breakup of liquid bridges with a free contact line\non a surface with contact-angle hysteresis under zero-gravity conditions.\nTheoretical predictions of the stability limits are validated by experimental\nmeasurements. Experiments are conducted in a water-methanol-silicon oil system\nwhere the gravity force is offset by buoyancy. We highlight cases where\nstability is lost during the transition from a pinned-pinned to pinned-free\ninterface when the receding contact angle is approached---rather than a\ncritical state, indicating that the breakup length is not always associated\nwith the static maximum-length stability limit. We demonstrate that the dynamic\ncontact angle controls the contact-line radius following stability loss, and\nthat interface evolution following stability loss can increase the\ndispensed-drop size if the contact angle is fixed.",
        "positive": "Elastic deformations of loaded core-shell systems: Macroscopic elastic core-shell systems can be generated as toy models to be\ndeformed and haptically studied by hand. On the mesoscale, colloidal core-shell\nparticles and microgels are fabricated and investigated by different types of\nmicroscopy. We analyse, using linear elasticity theory, the response of\nspherical core-shell systems under the influence of a line density of force\nthat is oriented radially and acts along the equator of the outer surface.\nInterestingly, deformational coupling of the shell to the core can determine\nthe resulting overall appearance in response to the forces. We address various\ncombinations of radii, stiffness, and Poisson ratio of core and shell and\nillustrate the resulting deformations. Macroscopically, the situation could be\nrealized by wrapping a cord around the equator of a macroscopic model system\nand pulling it tight. On the mesoscale, colloidal microgel particles\nsymmetrically confined to the interface between two immiscible fluids are\npulled radially outward by surface tension."
    },
    {
        "anchor": "Interface-Induced Ordering of Gas Molecules Confined in a Small Space: The thermodynamic properties of gases have been understood primarily through\nphase diagrams of bulk gases. However, observations of gases confined in a\nnanometer space have posed a challenge to the principles of classical\nthermodynamics. Here, we investigated interfacial structures comprising either\nO2 or N2 between water and a hydrophobic solid surface by using advanced atomic\nforce microscopy techniques. Ordered epitaxial layers and cap-shaped\nnanostructures were observed. In addition, pancake-shaped disordered layers\nthat had grown on top of the epitaxial base layers were observed in\noxygen-supersaturated water. We propose that hydrophobic solid surfaces provide\nlow-chemical-potential sites at which gas molecules dissolved in water can be\nadsorbed. The structures are further stabilized by interfacial water. Gas\nmolecules can agglomerate into a condensed form when confined in a sufficiently\nsmall space under ambient conditions. The ordering and thermodynamic properties\nof the confined gases are determined primarily according to interfacial\ninteractions. The crystalline solid surface may even induce a solid-gas state.",
        "positive": "Grazing incidence x-ray diffraction studies of lipid-peptide mixed\n  monolayers during shear flow: Grazing Incidence X-ray Diffraction (GIXD) studies of monolayers of\nbiomolecules at the air-water interface give quantitative information of\nin-plane packing, coherence lengths of the ordered diffracting crystalline\ndomains and the orientation of hydrocarbon chains. Rheo-GIXD measurements revel\nquantitative changes in the monolayer under shear. Here we report GIXD studies\nof monolayers of Alamethicin peptide, DPPC lipid and their mixtures at the\nair-water interface under the application of steady shear stresses. The\nAlamethicin monolayer and the mixed monolayer show flow jamming transition. On\nthe other hand, pure DPPC monolayer under the constant stress flows steadily\nwith a notable enhancement of area/molecule, coherence length, and the tilt\nangle with increasing stress, suggesting fusion of nanocrystallites during\nflow. The DPPC-Alamethicin mixed monolayer shows no significant change in the\narea/DPPC molecule or in the DPPC chain tilt but the coherence length of both\nphases (DPPC and Alamethicin) increases suggesting that the crystallites of\nindividual phases are merging to bigger size promoting more separation of\nphases in the system during flow. Our results show that Rheo-GIXD has the\npotential to explore in-situ molecular structural changes under rheological\nconditions for a diverse range of confined biomolecules at the interfaces."
    },
    {
        "anchor": "On the effective one-component description of highly asymmetric\n  hard-sphere binary fluid mixtures: The phase diagram of a binary fluid mixture of highly asymmetric additive\nhard spheres is investigated. Demixing is analyzed from the exact low-density\nexpansions of the thermodynamic properties of the mixture and compared with the\nfluid-fluid separation based on the effective one-component description.\nDifferences in the results obtained from both approaches, which have been\nclaimed to be equivalent, are pointed out and their possible origin is\ndiscussed. It is argued that to deal with these differences new theoretical\napproximations should be devised.",
        "positive": "Role of interfacial friction for flow instabilities in a thin polar\n  ordered active fluid layer: We construct a generic coarse-grained dynamics of a thin inflexible planar\nlayer of polar-ordered suspension of active particles, that is frictionally\ncoupled to an embedding isotropic passive fluid medium with a friction\ncoefficient $\\Gamma$. Being controlled by $\\Gamma$, our model provides a\nunified framework to describe the long wavelength behaviour of a variety of\nthin polar-ordered systems, ranging from {\\em wet} to {\\em dry} active matters\nand free standing active films. Investigations of the linear instabilities\naround a chosen orientationally ordered uniform reference state reveal generic\nmoving and static instabilities in the system, that can depend sensitively on\n$\\Gamma$. Based on our results, we discuss estimation of bounds on $\\Gamma$ in\nexperimentally accessible systems."
    },
    {
        "anchor": "Icosahedral packing of RNA viral genomes: Recent studies reveal that certain viruses package a portion of their genome\nin a manner that mirrors the icosahedral symmetry of the protein container, or\ncapsid. Graph theoretical constraints forbid exact realization of icosahedral\nsymmetry. This paper proposes a model for the determination of\nquasi-icosahedral genome structures and discusses the connection between\ngenomic structure and viral assembly kinetics.",
        "positive": "Curvature corrections to the nonlocal interfacial model for short-ranged\n  forces: In this paper we revisit the derivation of a nonlocal interfacial Hamiltonian\nmodel for systems with short-ranged intermolecular forces. Starting from a\nmicroscopic Landau-Ginzburg-Wilson Hamiltonian with a double parabola\npotential, we reformulate the derivation of the interfacial model using a\nrigorous boundary integral approach. This is done for three scenarios: a single\nfluid phase in contact with a nonplanar substrate (i.e., wall); a free\ninterface separating coexisting fluid phases (say, liquid and gas); and finally\na liquid-gas interface in contact with a nonplanar confining wall, as is\napplicable to wetting phenomena. For the first two cases our approaches\nidentifies the correct form of the curvature corrections to the free energy\nand, for the case of a free interface, it allows us to recast these as an\ninterfacial self-interaction as conjectured previously in the literature. When\nthe interface is in contact with a substrate our approach similarly identifies\ncurvature corrections to the nonlocal binding potential, describing the\ninteraction of the interface and wall, for which we propose a generalized and\nimproved diagrammatic formulation."
    },
    {
        "anchor": "Frame hydrodynamics of biaxial nematics from molecular-theory-based\n  tensor models: Starting from a dynamic tensor model about two second-order tensors, we\nderive the frame hydrodynamics for the biaxial nematic phase using the Hilbert\nexpansion. The coefficients in the frame model are derived from those in the\ntensor model. The energy dissipation of the tensor model is maintained in the\nframe model. The model is reduced to the Ericksen--Leslie model if the biaxial\nbulk energy minimum of the tensor model is reduced to a uniaxial one.",
        "positive": "Topology counts: force distributions in circular spring networks: Filamentous polymer networks govern the mechanical properties of many\nbiological materials. Force distributions within these networks are typically\nhighly inhomogeneous and, although the importance of force distributions for\nstructural properties is well recognized, they are far from being understood\nquantitatively. Using a combination of probabilistic and graph-theoretical\ntechniques we derive force distributions in a model system consisting of\nensembles of random linear spring networks on a circle. We show that\ncharacteristic quantities, such as mean and variance of the force supported by\nindividual springs, can be derived explicitly in terms of only two parameters:\n(i) average connectivity and (ii) number of nodes. Our analysis shows that a\nclassical mean-field approach fails to capture these characteristic quantities\ncorrectly. In contrast, we demonstrate that network topology is a crucial\ndeterminant of force distributions in an elastic spring network."
    },
    {
        "anchor": "Numerical electrokinetics: A new lattice method is presented in order to efficiently solve the\nelectrokinetic equations, which describe the structure and dynamics of the\ncharge cloud and the flow field surrounding a single charged colloidal sphere,\nor a fixed array of such objects. We focus on calculating the electrophoretic\nmobility in the limit of small driving field, and systematically linearise the\nequations with respect to the latter. This gives rise to several subproblems,\neach of which is solved by a specialised numerical algorithm. For the total\nproblem we combine these solvers in an iterative procedure. Applying this\nmethod, we study the effect of the screening mechanism (salt screening vs.\ncounterion screening) on the electrophoretic mobility, and find a weak\nnon-trivial dependence, as expected from scaling theory. Furthermore, we find\nthat the orientation of the charge cloud (i. e. its dipole moment) depends on\nthe value of the colloid charge, as a result of a competition between\nelectrostatic and hydrodynamic effects.",
        "positive": "Wetting properties of structured interfaces composed of surface-attached\n  spherical nanoparticles: The influence of the external pressure and surface energy on the wetting\ntransition at nanotextured interfaces is studied using molecular dynamics and\ncontinuum simulations. The surface roughness of the composite interface is\nintroduced via an array of spherical nanoparticles with controlled wettability.\nWe find that in the absence of an external pressure, the liquid interface is\nflat and its location relative to the solid substrate is determined by the\nparticle size and the local contact angle. With increasing pressure on the\nliquid film, the interface becomes more curved and the three-phase contact line\nis displaced along the spherical surface but remains stable due to re-entrant\ngeometry. It is demonstrated that the results of molecular dynamics simulations\nfor the critical pressure of the Cassie-Baxter wetting state agree well with\nthe estimate of the critical pressure obtained by numerical minimization of the\ninterfacial energy."
    },
    {
        "anchor": "Dynamics and Interactions of Quincke Roller Clusters: from Orbits and\n  Flips to Excited States: Active matter systems may be characterised by the conversion of energy into\nactive motion, e.g. the self-propulsion of microorganisms. Artificial active\ncolloids form models which exhibit essential properties of more complex\nbiological systems but are amenable to laboratory experiments. While most\nexperimental models consist of spheres, such as Janus particles, active\nparticles of different shapes are less understood. In particular, interactions\nbetween such active colloidal \"molecules\" are largely unexplored. Here, we\ninvestigate the motion of active colloidal molecules and the interactions\nbetween them. We focus on self-assembled dumbbells and trimers powered by an\nexternal electric field. For dumbbells, we observe an activity-dependent\nbehaviour of spinning, circular and orbital motion. Moreover, collisions\nbetween dumbbells lead to the hierarchical self-assembly of tetramers and\nhexamers, both of which form rotational excited states. On the other hand,\ntrimers exhibit a novel type of flipping motion that leads to trajectories\nreminiscent of a honeycomb lattice.",
        "positive": "Symmetry breaking and coarsening of clusters in a prototypical driven\n  granular gas: Granular hydrodynamics predicts symmetry-breaking instability in a\ntwo-dimensional (2D) ensemble of nearly elastically colliding smooth hard\nspheres driven, at zero gravity, by a rapidly vibrating sidewall. Super- and\nsubcritical symmetry-breaking bifurcations of the simple clustered state are\nidentified, and the supercritical bifurcation curve is computed. The cluster\ndynamics proceed as a coarsening process mediated by the gas phase. Far above\nthe bifurcation point the final steady state, selected by coarsening,\nrepresents a single strongly localized densely packed 2D cluster."
    },
    {
        "anchor": "Testing cosmological defect formation in the laboratory: Topological defects such as cosmic strings may have been formed at\nearly-universe phase transitions. Direct tests of this idea are impossible, but\nthe mechanism can be elucidated by studying analogous processes in\nlow-temperature condensed-matter systems. Experiments on vortex formation in\nsuperfluid helium and in superconductors have so far yielded somewhat confusing\nresults. I shall discuss their possible interpretation.",
        "positive": "Correction of Wall Adhesion Effects in the Centrifugal Compression of\n  Strong Colloidal Gels: Several methods for measuring the compressive strength of strong particulate\ngels are available, including the centrifuge method, whereby the strength as a\nfunction of volume-fraction is obtained parametrically from the dependence of\nequilibrium sediment height upon acceleration. The analysis used conventionally\ndue to Buscall & White (1987) ignores the possibility that the particulate\nnetwork might adhere to the walls of the centrifuge tube, even though many\ntypes of cohesive particulate gel can be expected to. The neglect of adhesion\nis justifiable when the ratio of the shear to compressive strength is small,\nwhich it can be for many systems away from the gel-point, but never very near\nit. The errors arising from neglect of adhesion are investigated theoretically\nand quantified by synthesising equilibrium sediment height versus acceleration\ndata for various degrees of adhesion and then analysing them in the\nconventional manner. Approximate correction factors suggested by dimensionless\nanalysis are then tested. The errors introduced by certain other approximations\nmade routinely in order to render the data-inversion practicable are analysed\ntoo. For example, it shown that the error introduced by treating the\nacceleration vector as approximately one-dimensional is minuscule for typical\ncentrifuge dimensions, whereas making this assumption renders the data\ninversion tractable."
    },
    {
        "anchor": "Connecting the grain-shearing mechanism of wave propagation in marine\n  sediments to fractional order wave equations: The characteristic time-dependent viscosity of the intergranular pore-fluid\nin Buckingham's grain-shearing (GS) model [Buckingham, J. Acoust. Soc. Am. 108,\n2796-2815 (2000)] is identified as the property of rheopecty. The property\ncorresponds to a rare type of a non-Newtonian fluid in rheology which has\nlargely remained unexplored. The material impulse response function from the GS\nmodel is found to be similar to the power-law memory kernel which is inherent\nin the framework of fractional calculus. The compressional wave equation and\nthe shear wave equation derived from the GS model are shown to take the form of\nthe Kelvin-Voigt fractional-derivative wave equation and the fractional\ndiffusion-wave equation respectively. Therefore, an analogy is drawn between\nthe dispersion relations obtained from the fractional framework and those from\nthe GS model to establish the equivalence of the respective wave equations.\nFurther, a physical interpretation of the characteristic fractional order\npresent in the wave equations is inferred from the GS model. The overall goal\nis to show that fractional calculus is not just a mathematical framework which\ncan be used to curve-fit the complex behavior of materials. Rather, it can also\nbe derived from real physical processes as illustrated in this work by the\nexample of grain-shearing.",
        "positive": "Protein-mediated Loops and Phase Transition in Nonthermal Denaturation\n  of DNA: We use a statistical mechanical model to study nonthermal denaturation of DNA\nin the presence of protein-mediated loops. We find that looping proteins which\nrandomly link DNA bases located at a distance along the chain could cause a\nfirst-order phase transition. We estimate the denaturation transition time near\nthe phase transition, which can be compared with experimental data. The model\ndescribes the formation of multiple loops via dynamical (fluctuational) linking\nbetween looping proteins, that is essential in many cellular biological\nprocesses."
    },
    {
        "anchor": "Wetting Transitions Displayed by Persistent Active Particles: A lattice model for active matter is studied numerically, showing that it\ndisplays wettings transitions between three distinctive phases when in contact\nwith an impenetrable wall. The particles in the model move persistently,\ntumbling with a small rate $\\alpha$, and interact via exclusion volume only.\nWhen increasing the tumbling rates $\\alpha$, the system transits from total\nwetting to partial wetting and unwetting phases. In the first phase, a wetting\nfilm covers the wall, with increasing heights when $\\alpha$ is reduced. The\nsecond phase is characterized by wetting droplets on the wall with a periodic\nspacing between them. Finally, the wall dries with few particles in contact\nwith it. These phases present nonequilibrium transitions. The first transition,\nfrom partial to total wetting, is continuous and the fraction of dry sites\nvanishes continuously when decreasing the tumbling rate $\\alpha$. For the\nsecond transition, from partial wetting to dry, the mean droplet distance\ndiverges logarithmically when approaching the critical tumbling rate, with\nsaturation due to finite-size effects.",
        "positive": "Damping of acoustic waves in dilute polymer solutions: The shear viscosity eta_s(w) of dilute polymer solutions (of flexible coils)\nhas been classically measured and interpreted in terms of the Zimm modes. We\npoint out that the longitudinal viscosity eta_l(w) is the sum of two components\neta_l=4*eta_s/3+eta_p, where eta_p is due to an effect of pressure on the coil\nsize. We discuss eta_p for a crude model involving a dependence of both the\nKuhn length a and the Flory parameter chi on pressure. We find that eta_p is\ncomparable to eta_s for good solvent conditions, but that eta_p should dominate\nover eta_s near the theta point."
    },
    {
        "anchor": "The role of lubricant molecular shape in microscopic friction: With the help of a simple two-dimensional model we simulate the tribological\nproperties of a thin lubricant film consisting of linear (chain) molecules in\nthe ordinary soft-lubricant regime. We find that friction generally increases\nwith chain length, in agreement with their larger bulk viscosity. When\ncomparing the tribological properties of molecules which stick bodily to the\nsubstrates with others carrying a single sticking termination, we find that the\nlatter generally yield a larger friction than the former.",
        "positive": "Raman spectroscopy of chocolate bloom: Raman spectroscopy has been widely applied to the chemical analysis of food\nquality and, in particular, of chocolate. We perform Raman analysis of bloom\nformation in white and dark chocolates. We show evidence of sugar and fat bloom\nand investigate spectroscopic signatures of polymorphic changes in different\nphases."
    },
    {
        "anchor": "Dynamic Fracture Model for Acoustic Emission: We study the acoustic emission produced by micro-cracks using a\ntwo-dimensional disordered lattice model of dynamic fracture, which allows to\nrelate the acoustic response to the internal damage of the sample. We find that\nthe distributions of acoustic energy bursts decays as a power law in agreement\nwith experimental observations. The scaling exponents measured in the present\ndynamic model can related to those obtained in the quasi-static random fuse\nmodel.",
        "positive": "Collapse of Stiff Polyelectrolytes due to Counterion Fluctuations: The effective elasticity of highly charged stiff polyelectrolytes is studied\nin the presence of counterions, with and without added salt. The rigid polymer\nconformations may become unstable due to an effective attraction induced by\ncounterion density fluctuations. Instabilities at the longest, or intermediate\nlength scales may signal collapse to globule, or necklace states, respectively.\nIn the presence of added-salt, a generalized electrostatic persistence length\nis obtained, which has a nontrivial dependence on the Debye screening length."
    },
    {
        "anchor": "Drag Coefficient of a Rigid Spherical Particle in a Near-Critical Binary\n  Fluid Mixture beyond the Regime of the Gaussian Model: The drag coefficient of a rigid spherical particle deviates from the Stokes\nlaw when it is put into a near-critical fluid mixture in the homogeneous phase\nwith the critical composition. The deviation ($\\Delta\\gamma_{\\rm d}$) is\nexperimentally shown to depend approximately linearly on the correlation length\nfar from the particle ($\\xi_\\infty$), and is suggested to be caused by the\npreferential attraction between one component and the particle surface. In\ncontrast, the dependence was shown to be much steeper in the previous\ntheoretical studies based on the Gaussian free-energy density. In the vicinity\nof the particle, especially when the adsorption of the preferred component\nmakes the composition strongly off-critical, the correlation length becomes\nvery small as compared with $\\xi_\\infty$. This spacial inhomogeneity, not\nconsidered in the previous theoretical studies, can influence the dependence of\n$\\Delta\\gamma_{\\rm d}$ on $\\xi_\\infty$. To examine this possibility, we here\napply the local renormalized functional theory, which was previously proposed\nto explain the interaction of walls immersed in a (near-)critical binary fluid\nmixture, describing the preferential attraction in terms of the surface field.\nThe free-energy density in this theory, coarse-grained up to the local\ncorrelation length, has much complicated dependence on the order parameter, as\ncompared with the Gaussian free-energy density. Still, a concise expression of\nthe drag coefficient, which was derived in one of the previous theoretical\nstudies, turns out to be available in the present formulation. We show that, as\n$\\xi_{\\infty}$ becomes larger, the dependence of $\\Delta\\gamma_{\\rm d}$ on\n$\\xi_\\infty$ becomes distinctly gradual and close to the linear dependence.",
        "positive": "Bistable defect structures in blue phase devices: Blue phases (BPs) are liquid crystals made up by networks of defects, or\ndisclination lines. While existing phase diagrams show a striking variety of\ncompeting metastable topologies for these networks, very little is known as to\nhow to kinetically reach a target structure, or how to switch from one to the\nother, which is of paramount importance for devices. We theoretically identify\ntwo confined blue phase I systems in which by applying an appropriate series of\nelectric field it is possible to select one of two bistable defect patterns.\nOur results may be used to realise new generation and fast switching\nenergy-saving bistable devices in ultrathin surface treated BPI wafers."
    },
    {
        "anchor": "Surface rheotaxis of three-sphere microrobots with cargo: Upstream swimming governs bacterial contamination, but also the navigation of\nmicrorobots transporting cargo in complex flow environments. We demonstrate how\nsuch payloads can be exploited to enhance the motion against flows. Using fully\nresolved simulations, the hydrodynamic mechanisms are revealed that allow\nmicrorobots of different shapes to reorient upstream. Cargo pullers are the\nfastest at most flow strengths, but pushers feature a non-trivial optimum that\ncan be tuned by their geometry. These results can be used to control navigation\nand prevent contamination from first principles.",
        "positive": "Lateral correlation of multivalent counterions is the universal\n  mechanism of charge inversion: We review works on screening of a macroion, such as colloidal particle or\ndouble helix DNA, by multivalent counterions. Multivalent metal ions, charged\nmicelles, short or long polyelectrolytes can play the role of multivalent\ncounterions. Due to the strong Coulomb repulsion such multivalent counterions\nform a strongly correlated liquid resembling a Wigner crystal at the surface of\nthe macroion. Even if the macroion is neutralized by this liquid, a newly\narriving counterion creates in the liquid a correlation hole or image which\nattracts the ion to the surface. As a result, total charge of adsorbed\ncounterions can substantially exceed the bare macroion charge, so that the\nmacroion net charge inverts its sign. We discuss two previously suggested\nexplanations of charge inversion and show that physics underlying both of them\nis intrinsically that of correlations, so that correlation is the universal\nforce driving charge inversion."
    },
    {
        "anchor": "Lyotropic chromonic liquid crystal semiconductors for water-solution\n  processable organic electronics: We propose lyotropic chromonic liquid crystals (LCLCs) as a distinct class of\nmaterials for organic electronics. In water, the chromonic molecules stack on\ntop of each other into elongated aggregates that form orientationally ordered\nphases. The aligned aggregated structure is preserved when the material is\ndeposited onto a substrate and dried. The dried LCLC films show a strongly\nanisotropic electric conductivity of semiconductor type. The field-effect\ncarrier mobility measured along the molecular aggregates in unoptimized films\nof LCLC V20 is 0.03 cm^2 V^(-1) s^(-1). Easy processibility, low cost, and high\nmobility demonstrate the potential of LCLCs for microelectronic applications.",
        "positive": "Precise Particle Tracking Against a Complicated Background: Polynomial\n  Fitting with Gaussian Weight: We present a new particle tracking software algorithm designed to accurately\ntrack the motion of low-contrast particles against a background with large\nvariations in light levels. The method is based on a polynomial fit of the\nintensity around each feature point, weighted by a Gaussian function of the\ndistance from the centre, and is especially suitable for tracking endogeneous\nparticles in the cell, imaged with bright field, phase contrast or fluorescence\noptical microscopy. Furthermore, the method can simultaneously track particles\nof all different sizes, and allows significant freedom in their shape. The\nalgorithm is evaluated using the quantitative measures of accuracy and\nprecision of previous authors, using simulated images at variable\nsignal-to-noise ratios. To these we add a new test of the error due to a\nnon-uniform background. Finally the tracking of particles in real cell images\nis demonstrated. The method is made freely available for non-commencial use as\na software package with a graphical user-inferface, which can be run within the\nMatlab programming environment."
    },
    {
        "anchor": "Statics and Dynamics of Colloid-Polymer Mixtures Near Their Critical\n  Point of Phase Separation: A Computer Simulation Study of a Continuous AO\n  Model: We propose a new coarse-grained model for the description of liquid-vapor\nphase separation of colloid-polymer mixtures. The hard-sphere repulsion between\ncolloids and between colloids and polymers, which is used in the well-known\nAsakura-Oosawa (AO) model, is replaced by Weeks-Chandler-Anderson potentials.\nSimilarly, a soft potential of height comparable to thermal energy is used for\nthe polymer-polymer interaction, rather than treating polymers as ideal gas\nparticles. It is shown by grand-canonical Monte Carlo simulations that this\nmodel leads to a coexistence curve that almost coincides with that of the AO\nmodel and the Ising critical behavior of static quantities is reproduced. Then\nthe main advantage of the model is exploited - its suitability for Molecular\nDynamics simulations - to study the dynamics of mean square displacements of\nthe particles, transport coefficients such as the self-diffusion and\ninterdiffusion coefficients, and dynamic structure factors. While the\nself-diffusion of polymers increases slightly when the critical point is\napproached, the self-diffusion of colloids decreases and at criticality the\ncolloid self-diffusion coefficient is about a factor of 10 smaller than that of\nthe polymers. Critical slowing down of interdiffusion is observed, which is\nqualitatively similar to symmetric binary Lennard-Jones mixtures, for which no\ndynamic asymmetry of self-diffusion coefficients occurs.",
        "positive": "The Correlation Potential of a Test Ion Near a Strongly Charged Plate: We analytically calculate the correlation potential of a test ion near a\n\\emph{strongly} charged plate inside a dilute $m:-n$ electrolyte. We do this by\ncalculating the electrostatic Green's function in the presence of a nonlinear\nbackground potential, the latter having been obtained using the nonlinear\nPoisson-Boltzmann theory. We consider the general case where the dielectric\nconstants of the plate and the electrolyte are distinct. The following generic\nresults emerge from our analyses: (1) If the distance to the plate $\\Delta z$\nis much larger than a Gouy-Chapman length, the plate surface will behave\neffectively as an infinitely charged surface, and the dielectric constant of\nthe plate effectively plays no role. (2) If $\\Delta z$ is larger than a\nGouy-Chapman length but shorter than a Debye length, the correlation potential\ncan be interpreted in terms of an image charge that is three times larger than\nthe source charge. This behavior is independent of the valences of the ions.\n(3) The Green's function vanishes inside the plate if the surface charge\ndensity is infinitely large; hence the electrostatic potential is constant\nthere. In this respect, a strongly charged plate behaves like a conductor\nplate. (4) If $\\Delta z$ is smaller than a Gouy-Chapman length, the correlation\npotential is dominated by the conventional image charge due to the dielectric\ndiscontinuity at the interface. (5) If $\\Delta z$ is larger than a Debye\nlength, the leading order behavior of the correlation potential will depend on\nthe valences of the ions in the electrolyte. Furthermore, inside an\n\\emph{asymmetric} electrolyte, the correlation potential is \\emph{singly}\nscreened, i.e., it undergoes exponential decay with a decay width equal to the\nDebye length."
    },
    {
        "anchor": "Using Molecular Simulation to Compute Transport Coefficients of\n  Molecular Gases: The existing kinetic theory of gases is based on an analytical approach that\nbecomes intractable for all but the simplest molecules. Here we propose a\nsimple numerical scheme to compute the transport properties of molecular gases\nin the limit of infinite dilution. The approach that we propose is approximate,\nbut our results for the diffusivity $D$, the viscosity $\\eta$ and the thermal\nconductivity $\\lambda$ of hard spheres, Lennard-Jones particles and rough hard\nspheres, agree well with the standard (lowest order) Chapman-Enskog results. We\nalso present results for a Lennard-Jones-dimer model for nitrogen, for which no\nanalytical results are available. In the case of poly-atomic molecules (we\nconsider n-octane), our method remains simple and gives good predictions for\nthe diffusivity and the viscosity. Computing the thermal conductivity of\npoly-atomic molecules requires an approximate treatment of their quantized\ninternal modes. We show that a well-known approximation that relates $\\lambda$\nto $D$ and $\\eta$, yields good results. We note that our approach should yield\na lower limit to the exact value of $D$, $\\eta$ and $\\lambda$. Interestingly,\nthe most sophisticated (higher-order) Chapman-Enskog results for rough hard\nspheres seem to violate this bound.",
        "positive": "Coarse-graining strategies in polymer solutions: We review a coarse-graining strategy (multiblob approach) for polymer\nsolutions in which groups of monomers are mapped onto a single atom (a blob)\nand effective blob-blob interactions are obtained by requiring the\ncoarse-grained model to reproduce some coarse-grained features of the\nzero-density isolated-chain structure. By tuning the level of coarse graining,\ni.e. the number of monomers to be mapped onto a single blob, the model should\nbe adequate to explore the semidilute regime above the collapse transition,\nsince in this case the monomer density is very small if chains are long enough.\nThe implementation of these ideas has been previously based on a\ntransferability hypothesis, which was not completely tested against\nfull-monomer results (Pierleoni et al., J. Chem. Phys, 127, 171102 (2007)). We\nstudy different models proposed in the past and we compare their predictions to\nfull-monomer results for the chain structure and the thermodynamics in the\nrange of polymer volume fractions \\Phi between 0 and 8. We find that the\ntransferability assumption has a limited predictive power if a\nthermodynamically consistent model is required. We introduce a new tetramer\nmodel parametrized in such a way to reproduce not only zero-density\nintramolecular and intermolecular two-body probabilities, but also some\nintramolecular three-body and four-body distributions. We find that such a\nmodel correctly predicts three-chain effects, the structure and the\nthermodynamics up to \\Phi ~ 2, a range considerably larger than that obtained\nwith previous simpler models using zero-density potentials. Our results show\nthe correctness of the ideas behind the multiblob approach but also that more\nwork is needed to understand how to develop models with more effective monomers\nwhich would allow us to explore the semidilute regime at larger chain volume\nfractions."
    },
    {
        "anchor": "Lattice Boltzmann simulations of lamellar and droplet phases: Lattice Boltzmann simulations are used to investigate spinodal decomposition\nin a two-dimensional binary fluid with equilibrium lamellar and droplet phases.\nWe emphasise the importance of hydrodynamic flow to the phase separation\nkinetics. For mixtures slightly asymmetric in composition the fluid phase\nseparates into bulk and lamellar phases with the lamellae forming distinctive\nspiral structures to minimise their elastic energy.",
        "positive": "Dilatancy transition in a granular model: We introduce a model of granular matter and use a stress ensemble to analyze\nshearing. Monte Carlo simulation shows the model to exhibit a second order\nphase transition, associated with the onset of dilatancy."
    },
    {
        "anchor": "The helix--coil transition on the worm--like chain: I propose a variation of the standard worm--like chain model to account for\ninternal order parameter (helix/coil) fields on the polymer chain. This\ninternal order parameter field influences polymer conformational statistics by\nlocally modifying the persistence length of the chain. Using this model, I make\npredictions for the bending and stretching response of an alpha-helical domain\nof a protein. In particular, I show that alpha-helical protein domains will\nbuckle under applied torque. This highly nonlinear elastic behavior may be\nimportant in the understanding of allosteric control of biochemical pathways.",
        "positive": "Axisymmetric Stokes flow due to a point-force singularity acting between\n  two coaxially positioned rigid no-slip disks: We investigate theoretically on the basis of the steady Stokes equations for\na viscous incompressible fluid the flow induced by a Stokeslet located on the\ncentre axis of two coaxially positioned rigid disks. The Stokeslet is directed\nalong the centre axis. No-slip boundary conditions are assumed to hold at the\nsurfaces of the disks. We perform the calculation of the associated Green's\nfunction in large parts analytically, reducing the spatial evaluation of the\nflow field to one-dimensional integrations amenable to numerical treatment. To\nthis end, we formulate the solution of the hydrodynamic problem for the viscous\nflow surrounding the two disks as a mixed-boundary-value problem, which we then\nreduce into a system of four dual integral equations. We show the existence of\nviscous toroidal eddies arising in the fluid domain bounded by the two disks,\nmanifested in the plane containing the centre axis through adjacent\ncounterrotating eddies. Additionally, we probe the effect of the confining\ndisks on the slow dynamics of a point-like particle by evaluating the\nhydrodynamic mobility function associated with axial motion. Thereupon, we\nassess the appropriateness of the commonly-employed superposition approximation\nand discuss its validity and applicability as a function of the geometrical\nproperties of the system. Additionally, we complement our semi-analytical\napproach by finite-element computer simulations, which reveals a good\nagreement. Our results may find applications in guiding the design of\nmicroparticle-based sensing devices and electrokinetic transport in small scale\ncapacitors."
    },
    {
        "anchor": "Characterization of the sub-micrometer hierarchy levels in the\n  twist-bend nematic phase with nanometric helices via photopolymerization.\n  Explanation for the sign reversal in the polar response: Photo-polymerization of a reactive mesogen mixed with a mesogenic dimer,\nshown to exhibit the twist-bend nematic phase ($N_{TB}$), reveals the complex\nstructure of the self-deformation patterns observed in planar cells. The\npolymerized reactive mesogen retains the structure formed by liquid crystalline\nmolecules in the twist bend phase, thus enabling observation by Scanning\nElectron Microscope (SEM). Hierarchical ordering scales from tens of nanometers\nto micrometers are imaged in detail. Submicron features, anticipated from\nearlier X-ray experiments, are visualized directly. In the self-deformation\nstripes formed in the $N_{TB}$ phase, the average director field is found\ntilted in the cell plane by an angle of up to 45$^{\\circ}$ from the cell\nrubbing direction. This tilting explains the sign inversion being observed in\nthe electro-optical studies.",
        "positive": "Tracer diffusion in colloidal gels: Computer simulations were done of the mean square displacement (MSD) of\ntracer particles in colloidal gels formed by diffusion or reaction limited\naggregation of hard spheres. The diffusion coefficient was found to be\ndetermined by the volume fraction accessible to the spherical tracers\n($\\phi_a$) independent of the gel structure or the tracer size. In all cases,\ncritical slowing down was observed at $\\phi_a\\approx 0.03$ and was\ncharacterized by the same scaling laws reported earlier for tracer diffusion in\na Lorentz gas. Strong heterogeneity of the MSD was observed at small $\\phi_a$\nand was related to the size distribution of pores."
    },
    {
        "anchor": "Average Time Spent by Levy Flights and Walks on an Interval with\n  Absorbing Boundaries: We consider a Levy flyer of order alpha that starts from a point x0 on an\ninterval [O,L] with absorbing boundaries. We find a closed-form expression for\nthe average number of flights the flyer takes and the total length of the\nflights it travels before it is absorbed. These two quantities are equivalent\nto the mean first passage times for Levy flights and Levy walks, respectively.\nUsing fractional differential equations with a Riesz kernel, we find exact\nanalytical expressions for both quantities in the continuous limit. We show\nthat numerical solutions for the discrete Levy processes converge to the\ncontinuous approximations in all cases except the case of alpha approaching 2\nand the cases of x0 near absorbing boundaries. For alpha larger than 2 when the\nsecond moment of the flight length distribution exists, our result is replaced\nby known results of classical diffusion. We show that if x0 is placed in the\nvicinity of absorbing boundaries, the average total length has a minimum at\nalpha=1, corresponding to the Cauchy distribution. We discuss the relevance of\nthis result to the problem of foraging, which has received recent attention in\nthe statistical physics literature.",
        "positive": "Emergence of Tension Chains and Active Force Patterning: Viewed under a fluorescence microscope, the actomyosin cytoskeleton presents\nvivid streaks of lines together with persistent oscillatory waves. Using an\nactive hydrodynamic approach, we show how a uniform distribution of single or\nmixture of contractile stresslets spontaneously segregate, followed by the\nformation of singular structures of high contractility (tension chains) in\nfinite time. Simultaneously, the collection of stresslets exhibit travelling\nwaves and swapping as a consequence of nonreciprocity. In the finite geometry\nof the cell, the collection of active tension chains can form an active web\nheld together by specific anchoring at the cell boundary. On the other hand,\npreferential wetting at the cell boundary can reinforce active segregation in a\nmixture of stresslets leading to stratification."
    },
    {
        "anchor": "Molecular engineering of chiral colloidal liquid crystals using DNA\n  origami: Establishing precise control over the shape and the interactions of the\nmicroscopic building blocks is essential for design of macroscopic soft\nmaterials with novel structural, optical and mechanical properties. Here, we\ndemonstrate robust assembly of DNA origami filaments into cholesteric liquid\ncrystals, 1D supramolecular twisted ribbons and 2D colloidal membranes. The\nexquisite control afforded by the DNA origami technology establishes a\nquantitative relationship between the microscopic filament structure and the\nmacroscopic cholesteric pitch. Furthermore, it also enables robust assembly of\n1D twisted ribbons, which behave as effective supramolecular polymers whose\nstructure and elastic properties can be precisely tuned by controlling the\ngeometry of the elemental building blocks. Our results demonstrate the\npotential synergy between DNA origami technology and colloidal science, in\nwhich the former allows for rapid and robust synthesis of complex particles,\nand the latter can be used to assemble such particles into bulk materials.",
        "positive": "Freezing of a soft-core fluid in a one-dimensional potential: Appearance\n  of a locked smectic phase: We investigate the phase behaviour of a two-dimensional colloidal model\nsystem of ultra-soft particles on a substrate which varies periodically along\none spatial direction. Our calculations are based on mean-field density\nfunctional theory for a system of particles interacting via an ultra-soft\npotential, that is, the generalized exponential model with index four\n(\\mbox{GEM-4}). For suitable substrate periodicities (with commensurability\nparameter $p=2$), we find a succession of phase transitions from a modulated\nliquid to a locked smectic and then to a locked floating solid phase. The\nappearance of a locked smectic phase is consistent with earlier theoretical\npredictions and experiments for freezing of more repulsive systems on\nstructured surfaces (with $p=2$). However, the present ultra-soft system does\nnot display re-entrant melting. We here investigate the details of the density\ndistributions of the different phases, thereby supplementing earlier work on\nGEM-4 systems with $p=1$ [Phys. Rev. E \\textbf{101}, 012609 (2020)].\nInterestingly, the observed succession of phase transitions can be triggered\nthrough different paths along which physical control parameters are changed."
    },
    {
        "anchor": "Effects of interfaces on dynamics in micro-fluidic devices:\n  slip-boundaries' impact on rotation characteristics of polar liquid film\n  motors: Slip-boundary effects on the polar liquid film motor (PLFM) -- a novel\nmicro-fluidic device with important implications for advancing knowledge on\nliquid micro-film's structure, dynamics, modeling and technology -- are\nstudied. We develop a mathematical model, under slip boundary conditions,\ndescribing electro-hydro-dynamical rotations in the PLFMs induced either by\ndirect current (DC) or alternating current (AC) fields. Our main results are:\n(i) rotation characteristics depend on the ratio $k=l_{s}/D$ ($l_{s}$ denotes\nthe slip length, resulting from the interface's impact on the structure of the\nliquid and $D$ denotes the film's diameter). (ii) As $k$ ($k>-1/2$) increases:\n(a) PLFMs subsequently exhibit rotation characteristics under \"negative-\",\n\"no-\", \"partial-\" and \"perfect-\" slip boundary conditions; (b) the maximum\nvalue of the linear velocity of the steady rotating liquid film increases and\nits location approaches the film's border; (c) the decay of the angular\nvelocities' dependency on the distance from the center of the film slows down,\nresulting in a macroscopic flow near the boundary. (iii) In addition to $k$,\nthe rotation characteristics of the AC PLFM depend on the magnitudes, the\nfrequencies, and the phase difference of the AC fields. (iv) Our analytical\nderived rotation speed distributions are consistent with the existing\nexperimental ones.",
        "positive": "Axiomatic Theories of Intermediate Phases (IP) and Ideal Stretched\n  Exponential Relaxation (SER): Minimalist theories of complex systems are broadly of two kinds: mean-field\nand axiomatic. So far all theories of properties absent from simple systems and\nintrinsic to complex systems, such as IP and SER, are axiomatic. SER is the\nprototypical complex temporal property of glasses, discovered by Kohlrausch 150\nyears ago, and now observed almost universally in microscopically homogeneous,\ncomplex non-equilibrium materials (strong network and fragile molecular\nglasses, polymers and copolymers, even electronic glasses). The Scher-Lax trap\nmodel (1973) is paradigmatic for electronic SER; for molecular SER Phillips\n(3RCS 1995) identified two \"magic\" shape fractions \\beta = 3/5 and 3/7, as\nconfirmed by many later experiments here reviewed. In the dielectric SER\nfrequency domain involving ion conduction, there are also special beta values\nfor fused salts and glasses, slightly, but distinguishably, different because\nof the presence of a forcing electric field."
    },
    {
        "anchor": "Probing the role of mobility in the collective motion of non-equilibrium\n  systems: By systematically varying the mobility of self-propelled particles in a\ntwo-dimensional (2D) lattice, we experimentally study the influence of particle\nmobility on system's collective motion. Our system is intrinsically\nnon-equilibrium due to the lack of energy equipartition. By constructing the\ncovariance matrix of spatial fluctuations and solving for its eigenmodes, we\nobtain the collective motions of the system with various magnitudes.\nInterestingly, our structurally ordered non-equilibrium system exhibits almost\nidentical properties as disordered glassy systems under thermal equilibrium:\nthe modes with large overall motions are spatially correlated and\nquasilocalized while the modes with small collective motions are highly\nlocalized, resembling the low- and high-frequency modes in glass. More\nsurprisingly, a peak similar to the boson peak forms in our non-equilibrium\nsystem as the number of mobile particles increases, revealing the possible\norigin of the boson peak from a dynamic aspect. We further illustrate that the\nspatially-correlated large-movement modes can be produced by the cooperation of\nhighly-active particles above a threshold fraction, while the localized\nsmall-movement modes can be created by adding individual inactive particles.\nOur study clarifies the role of mobility in collective motions, and further\nsuggests a promising possibility of extending the powerful mode analysis\napproach to non-equilibrium systems.",
        "positive": "The role of counterions in ionic liquid crystals: Previous theoretical studies of calamitic (i.e., rod-like) ionic liquid\ncrystals (ILCs) based on an effective one-species model led to indications of a\nnovel smectic-A phase with a layer spacing being much larger than the length of\nthe mesogenic (i.e., liquid-crystal forming) ions. In order to rule out the\npossibility that this wide smectic-A phase is merely an artifact caused by the\none-species approximation, we investigate an extension which accounts\nexplicitly for cations and anions in ILCs. Our present findings, obtained by\ngrand canonical Monte Carlo simulations, show that the phase transitions\nbetween the isotropic and the smectic-A phases of the cation-anion system are\nin qualitative agreement with the effective one-species model used in the\npreceding studies. In particular, for ILCs with mesogenes (i.e., liquid-crystal\nforming species) carrying charged sites at their tips, the wide smectic-A phase\nforms, at low temperatures and within an intermediate density range, in between\nthe isotropic and a hexagonal crystal phase. We find that in the ordinary\nsmectic-A phase the spatial distribution of the counterions of the mesogens is\napproximately uniform, whereas in the wide smectic-A phase the small\ncounterions accumulate in between the smectic layers. Due to this phenomenology\nthe wide smectic-A phase could be interesting for applications which hinge on\nthe presence of conductivity channels for mobile ions."
    },
    {
        "anchor": "Evolution of Maximum Bending Strain on Poisson's Ratio Distribution: In recent years, new flexible functional materials have attracted increasing\ninterest, but there is a lack of the designing mechanisms of flexibility design\nwith superstructures. In traditional engineering mechanics, the maximum bending\nstrain (MBS) was considered universal for describing the bendable properties of\na given material, leading to the universal designing method of lowering the\ndimension such as thin membranes designed flexible functional materials.In this\nwork, the MBS was found only applicable for materials with uniformly\ndistributed Poisson's ratio, while the MBS increases with the thickness of the\ngiven material in case there is a variation Poisson's ratio in different areas.\nThis means the MBS can be enhanced by certain Poisson's ratio design in the\nfuture to achieve better flexibility of thick materials. Here, the inorganic\nfreestanding nanofiber membranes, which have a nonconstant Poisson's ratio\nresponse on stress/strain for creating nonuniformly distributed Poisson's ratio\nwere proven applicable for designing larger MBS and lower Young's modulus for\nthicker samples.",
        "positive": "Membrane tension lowering induced by protein activity: We present measurements of the fluctuation spectrum of giant vesicles\ncontaining bacteriorhodopsin (BR) pumps using video-microscopy. When the pumps\nare activated, we observe a significant increase of the fluctuations in the low\nwavevector region, which we interpret as due to a lowering of the effective\ntension of the membrane."
    },
    {
        "anchor": "Accelerated relaxation in disordered solids under cyclic loading with\n  alternating shear orientation: The effect of alternating shear orientation during cyclic loading on the\nrelaxation dynamics in disordered solids is examined using molecular dynamics\nsimulations. The model glass was initially prepared by rapid cooling from the\nliquid state and then subjected to cyclic shear along a single plane or\nperiodically alternated in two or three dimensions. We showed that with\nincreasing strain amplitude in the elastic range, the system is relocated to\ndeeper energy minima. Remarkably, it was found that each additional alternation\nof the shear orientation in the deformation protocol brings the glass to lower\nenergy states. The results of mechanical tests after more than a thousand shear\ncycles indicate that cyclic loading leads to the increase in strength and\nshear-modulus anisotropy.",
        "positive": "Confinement Effects on Phase Behavior of Soft Matter Systems: When systems that can undergo phase separation between two coexisting phases\nin the bulk are confined in thin film geometry between parallel walls, the\nphase behavior can be profoundly modified. These phenomena shall be described\nand exemplified by computer simulations of the Asakura-Oosawa model for\ncolloid-polymer mixtures, but applications to other soft matter systems (e.g.\nconfined polymer blends) will also be mentioned. Typically a wall will prefer\none of the phases, and hence the composition of the system in the direction\nperpendicular to the walls will not be homogeneous. If both walls are of the\nsame kind, this effect leads to a distortion of the phase diagram of the system\nin thin film geometry, in comparison with the bulk, analogous to the phenomenon\nof \"capillary condensation\" of simple fluids in thin capillaries. In the case\nof \"competing walls\", where both walls prefer different phases of the two\nphases coexisting in the bulk, a state with an interface parallel to the walls\ngets stabilized. The transition from the disordered phase to this \"soft mode\nphase\" is rounded by the finite thickness of the film and not a sharp phase\ntransition. However, a sharp transition can occur where this interface gets\nlocalized at (one of) the walls. The relation of this interface localization\ntransition to wetting phenomena is discussed. Finally, an outlook to related\nphenomena is given, such as the effects of confinement in cylindrical pores on\nthe phase behavior, and more complicated ordering phenomena (lamellar\nmesophases of block copolymers or nematic phases of liquid crystals under\nconfinement)."
    },
    {
        "anchor": "Angular velocity distribution of a granular planar rotator in a\n  thermalized bath: The kinetics of a granular planar rotator with a fixed center undergoing\ninelastic collisions with bath particles is analyzed both numerically and\nanalytically by means of the Boltzmann equation. The angular velocity\ndistribution evolves from quasi-gaussian in the Brownian limit to an algebraic\ndecay in the limit of an infinitely light particle. In addition, we compare\nthis model with a planar rotator with a free center. We propose experimental\ntests that might confirm the predicted behaviors.",
        "positive": "Soft-mode and Anderson-like localization in two-phase disordered media: Wave localization is ubiquitous in disordered media -- from amorphous\nmaterials, where soft-mode localization is closely related to materials\nfailure, to semi-conductors, where Anderson localization leads to\nmetal-insulator transition. Our main understanding, though, is based on\ndiscrete models. Here, we provide a continuum perspective on the wave\nlocalization in two-phase disordered elastic media by studying the scalar wave\nequation with heterogeneous modulus and/or density. At low frequencies, soft\nmodes arise as a result of disordered elastic modulus, which can also be\npredicted by the localization landscape. At high frequencies, Anderson-like\nlocalization occurs due to disorder either in density or modulus. For the\nlatter case, we demonstrate how the vibrational dynamics changes from plane\nwaves to diffusons with increasing frequency. Finally, we discuss the\nimplications of our findings on the design of architected soft materials."
    },
    {
        "anchor": "Propulsion in a viscoelastic fluid: Flagella beating in complex fluids are significantly influenced by\nviscoelastic stresses. Relevant examples include the ciliary transport of\nrespiratory airway mucus and the motion of spermatozoa in the mucus-filled\nfemale reproductive tract. We consider the simplest model of such propulsion\nand transport in a complex fluid, a waving sheet of small amplitude free to\nmove in a polymeric fluid with a single relaxation time. We show that, compared\nto self-propulsion in a Newtonian fluid occurring at a velocity U_N, the sheet\nswims (or transports fluid) with velocity U / U_N = [1+De^2 (eta_s)/(eta)\n]/[1+De^2], where eta_s is the viscosity of the Newtonian solvent, eta is the\nzero-shear-rate viscosity of the polymeric fluid, and De is the Deborah number\nfor the wave motion, product of the wave frequency by the fluid relaxation\ntime. Similar expressions are derived for the rate of work of the sheet and the\nmechanical efficiency of the motion. These results are shown to be independent\nof the particular nonlinear constitutive equations chosen for the fluid, and\nare valid for both waves of tangential and normal motion. The generalization to\nmore than one relaxation time is also provided. In stark contrast with the\nNewtonian case, these calculations suggest that transport and locomotion in a\nnon-Newtonian fluid can be conveniently tuned without having to modify the\nwaving gait of the sheet but instead by passively modulating the material\nproperties of the liquid.",
        "positive": "Speed-Dispersion Induced Alignment : a 1D model inspired by swimming\n  droplets experiments: We investigate the collective dynamics of self-propelled droplets, confined\nin a one dimensional micro-fluidic channel. On one hand, neighboring droplets\nalign and form large trains of droplets moving in the same direction. On the\nother hand, the droplets condensates, leaving large regions with very low\ndensity. A careful examination of the interactions between two \"colliding\"\ndroplets demonstrates that local alignment takes place as a result of the\ninterplay between the dispersion of their speeds and the absence of Galilean\ninvariance. Inspired by these observations, we propose a minimalistic 1D model\nof active particles reproducing such dynamical rules and, combining analytical\narguments and numerical evidences, we show that the model exhibits a transition\nto collective motion in 1D for a large range of values of the control\nparameters. Condensation takes place as a transient phenomena which\ntremendously slows down the dynamics, before the system eventually settles into\na homogeneous aligned phase."
    },
    {
        "anchor": "Floating active carpets drive transport and aggregation in aquatic\n  ecosystems: Communities of swimming microorganisms often thrive near liquid-air\ninterfaces. We study how such `active carpets' shape their aquatic environment\nby driving biogenic transport in the water column beneath the active carpet.\nThe collective flows that these organisms generate lead to diffusive upward\nfluxes of nutrients from deeper water layers, and downward fluxes of oxygen and\ncarbon. Combining analytical theory and simulations, we examine the key\ntransport metrics including the single and pair diffusivity, the first passage\ntime for particle pair encounters, and the rate of particle aggregation. Our\nfindings reveal that the hydrodynamic fluctuations driven by active carpets\nhave a region of influence that reaches orders of magnitude further in distance\nthan the size of the organisms. These non-equilibrium fluctuations lead to a\nstrongly enhanced diffusion of particles, which is anisotropic and\nspace-dependent. The fluctuations also facilitate encounters of particle pairs,\nwhich we quantify by analyzing their velocity pair correlation functions as a\nfunction of distance between the particles. We found that the size of the\nparticles plays a crucial role in their encounter rates, with larger particles\nsituated near the active carpet being more favourable for aggregation. Overall,\nthis research has broadened our comprehension of aquatic systems out of\nequilibrium, particularly how biologically driven fluctuations contribute to\nthe transport of fundamental elements in biogeochemical cycles.",
        "positive": "Granular front formation in free-surface flow of concentrated\n  suspensions: Granular fronts are a common yet unexplained phenomenon emerging during the\ngravity driven free-surface flow of concentrated suspensions. They are usually\nbelieved to be the result of fluid convection in combination with particle size\nsegregation. However, suspensions composed of uniformly sized particles also\ndevelop a granular front. Within a large rotating drum, a stationary\nrecirculating avalanche is generated. The flowing material is a mixture of a\nvisco-plastic fluid obtained from a kaolin-water dispersion, with spherical\nceramic particles denser than the fluid. The goal is to mimic the composition\nof many common granular-fluid materials, like fresh concrete or debris flow. In\nthese materials, granular and fluid phases have the natural tendency to\nsegregate due to particle settling. However, through the shearing caused by the\nrotation of the drum, a reorganization of the phases is induced, leading to the\nformation of a granular front. By tuning the material properties and the drum\nvelocity, it is possible to control this phenomenon. The setting is reproduced\nin a numerical environment, where the fluid is solved by a Lattice-Boltzmann\nMethod, and the particles are explicitly represented using the Discrete Element\nMethod. The simulations confirm the findings of the experiments, and provide\ninsight into the internal mechanisms. Comparing the time-scale of particle\nsettling with the one of particle recirculation, a non-dimensional number is\ndefined, and is found to be effective in predicting the formation of a granular\nfront."
    },
    {
        "anchor": "Coherent Atomic Oscillations and Resonances between Coupled\n  Bose-Einstein Condensates with Time-Dependent Trapping Potential: We study the quantum coherent-tunneling between two Bose-Einstein condensates\nseparated through an oscillating trap potential. The cases of slowly and\nrapidly varying in time trap potential are considered. In the case of a slowly\nvarying trap we study the nonlinear resonances and chaos in the oscillations of\nthe relative atomic population. Using the Melnikov function approach, we find\nthe conditions for chaotic macroscopic quantum-tunneling phenomena to exists.\nCriteria for the onset of chaos are also given. We find the values of frequency\nand modulation amplitude which lead to chaos on oscillations in the relative\npopulation, for any given damping and the nonlinear atomic interaction. In the\ncase of a rapidly varying trap we use the multiscale expansion method in the\nparameter epsilon = 1/Omega, where Omega is the frequency of modulations and we\nderive the averaged system of equations for the modes. The analysis of this\nsystem shows that new macroscopic quantum self trapping regions, in comparison\nwith the constant trap case, exist.",
        "positive": "Dynamics of Associative Polymers with High Density of Reversible Bonds: We design and synthesize unentangled associative polymers carrying\nunprecedented high fractions of stickers, up to eight per Kuhn segment, that\ncan form strong pairwise hydrogen bonding of $\\sim20k_BT$ without microphase\nseparation. The reversible bonds significantly slow down the polymer dynamics\nbut nearly do not change the shape of linear viscoelastic spectra. Moreover,\nthe structural relaxation time of associative polymers increases exponentially\nwith the fraction of stickers and exhibits a universal yet non-Arrhenius\ndependence on the distance from polymer glass transition temperature. These\nresults cannot be understood within the framework of the classic sticky-Rouse\nmodel but are rationalized by a renormalized Rouse model, which highlights an\nunexpected influence of reversible bonds on the structural relaxation rather\nthan the shape of viscoelastic spectra for associative polymers with high\nconcentrations of stickers."
    },
    {
        "anchor": "Spatial and temporal spectra of noise driven stripe patterns: Spatial and temporal noise power spectra of stripe patterns are investigated,\nusing as a model a Swift-Hohenberg equation with a stochastic term. In\nparticular, the analytical and numerical investigations show: 1) the temporal\nnoise spectra are of 1/f^alpha form, where alpha=1+(3-D)/4 with D the spatial\ndimension of the system; 2) that the stochastic fluctuations of the stripe\nposition are sub-diffusive.",
        "positive": "Collapse or Swelling Dynamics of Homopolymer Rings: Self-consistent\n  Hartree approach: We investigate by the use of the Martin - Siggia - Rose generating functional\ntechnique and the self - consistent Hartree approximation, the dynamics of the\nring homopolymer collapse (swelling) following an instantaneous change into a\npoor (good) solvent conditions.The equation of motion for the time dependent\nmonomer - to - monomer correlation function is systematically derived. It is\nargued that for describing of the coarse - graining process (which neglects the\ncapillary instability and the coalescence of ``pearls'') the Rouse mode\nrepresentation is very helpful, so that the resulting equations of motion can\nbe simply solved numerically. In the case of the collapse this solution is\nanalyzed in the framework of the hierarchically crumpled fractal picture, with\ncrumples of successively growing scale along the chain. The presented numerical\nresults are in line with the corresponding simple scaling argumentation which\nin particular shows that the characteristic collapse time of a segment of\nlength $g$ scales as $t^* \\sim \\zeta_0 g/\\tau$ (where $\\zeta_0$ is a bare\nfriction coefficient and $\\tau$ is a depth of quench). In contrast to the\ncollapse the globule swelling can be seen (in the case that topological effects\nare neglected) as a homogeneous expansion of the globule interior. The swelling\nof each Rouse mode as well as gyration radius $R_g$ is discussed."
    },
    {
        "anchor": "Discrete charge patterns, Coulomb correlations and interactions in\n  protein solutions: The effective Coulomb interaction between globular proteins is calculated as\na function of monovalent salt concentration $c_s$, by explicit Molecular\nDynamics simulations of pairs of model proteins in the presence of microscopic\nco and counterions. For discrete charge patterns of monovalent sites on the\nsurface, the resulting osmotic virial coefficient $B_2$ is found to be a\nstrikingly non-monotonic function of $c_s$. The non-monotonicity follows from a\nsubtle Coulomb correlation effect which is completely missed by conventional\nnon-linear Poisson-Boltzmann theory and explains various experimental findings.",
        "positive": "Phase separation of passive particles in active liquids: The transport properties of colloidal particles in active liquids have been\nstudied extensively. It has led to a deeper understanding of the interactions\nbetween passive and active particles. However, the phase behavior of colloidal\nparticles in active media has received little attention. Here, we present a\ncombined experimental and numerical investigation of passive colloids dispersed\nin suspensions of active particles. Our study reveals dynamic clustering of\ncolloids in active media due to an interplay of active noise and an attractive\neffective potential between the colloids. The size-ratio of colloidal particles\nto the bacteria sets the strength of the interaction. As the relative size of\nthe colloids increases, the effective potential becomes stronger and the\naverage size of the clusters grows. The simulations reveal a macroscopic phase\nseparation of passive colloids at sufficiently large size-ratios. We will\npresent the role of density fluctuations and hydrodynamic interactions in the\nemergence of effective interactions."
    },
    {
        "anchor": "Pause Point Spectra in DNA Constant-Force Unzipping: Under constant applied force, the separation of double-stranded DNA into two\nsingle strands is known to proceed through a series of pauses and jumps. Given\nexperimental traces of constant-force unzipping, we present a method whereby\nthe locations of pause points can be extracted in the form of a pause point\nspectrum. A simple theoretical model of DNA constant-force unzipping is\ndemonstrated to produce good agreement with the experimental pause point\nspectrum of lambda phage DNA. The locations of peaks in the experimental and\ntheoretical pause point spectra are found to be nearly coincident below 6000\nbp. The model only requires the sequence, temperature and a set of empirical\nbase pair binding and stacking energy parameters, and the good agreement with\nexperiment suggests that pause points are primarily determined by the DNA\nsequence. The model is also used to predict pause point spectra for the\nBacterioPhage PhiX174 genome. The algorithm for extracting the pause point\nspectrum might also be useful for studying related systems which exhibit\npausing behavior such as molecular motors.",
        "positive": "Fractal dimensions of jammed packings with power-law particle size\n  distributions in two and three dimensions: Static structure factors are computed for large-scale, mechanically stable,\njammed packings of frictionless spheres (three dimensions) and disks (two\ndimensions) with broad, power-law size dispersity characterized by the exponent\n$-\\beta$. The static structure factor exhibits diverging power-law behavior for\nsmall wavenumbers, allowing us to identify a structural fractal dimension,\n$d_f$. In three dimensions, $d_f \\approx 2.0$ for $2.5 \\le \\beta \\le 3.8 $,\nsuch that each of the structure factors can be collapsed onto a universal\ncurve. In two dimensions, we instead find $1.0 \\lesssim d_f \\lesssim 1.34 $ for\n$2.1 \\le \\beta \\le 2.9 $. Furthermore, we show that the fractal behavior\npersists when rattler particles are removed, indicating that the long\nwavelength structural properties of the packings are controlled by the large\nparticle backbone conferring mechanical rigidity to the system. A numerical\nscheme for computing structure factors for triclinic unit cells is presented\nand employed to analyze the jammed packings."
    },
    {
        "anchor": "Geometric strong segregation theory for compositionally asymmetric\n  diblock copolymer melts: We have identified the effect of the Wigner-Seitz cell geometry in the strong\nsegregation limit of diblock copolymer melts with strong composition asymmetry.\nA variational problem is proposed describing the distortions of the chain paths\ndue to the geometric constraints imposed by the cell shape. We computed the\ngeometric excess energies for cylindrical phases arranged into hexagonal,\nsquare, and triangular lattices and explicitly demonstrated that the hexagonal\nlattice has the lowest energy for a fixed cell area.",
        "positive": "Scaling behavior for ionic transport and its fluctuations in individual\n  carbon nanotubes: In this letter we perform an experimental study of ionic transport and\ncurrent fluctuations inside individual Carbon Nanotubes (CNT). The conductance\nexhibits a power law behavior at low salinity, with an exponent close to 1/3\nversus the salt concentration. This scaling behavior is rationalized in terms\nof a model accounting for hydroxide adsorption at the (hydrophobic) carbon\nsurface, leading to a density dependent surface charge. This is in contrast to\nboron nitride nanotubes which exhibit a constant surface conductance. Further\nwe measure the low frequency noise of the ionic current in CNT and show that\nthe amplitude of the noise scales with the surface charge, with data collapsing\non a master curve for the various studied CNT at a given pH."
    },
    {
        "anchor": "Static Rouse Modes and Related Quantities: Corrections to Chain Ideality\n  in Polymer Melts: Following the Flory ideality hypothesis intrachain and interchain excluded\nvolume interactions are supposed to compensate each other in dense polymer\nsystems. Multi-chain effects should thus be neglected and polymer conformations\nmay be understood from simple phantom chain models. Here we provide evidence\nagainst this phantom chain, mean-field picture. We analyze numerically and\ntheoretically the static correlation function of the Rouse modes. Our numerical\nresults are obtained from computer simulations of two coarse-grained polymer\nmodels for which the strength of the monomer repulsion can be varied, from full\nexcluded volume (`hard monomers') to no excluded volume (`phantom chains'). For\nnonvanishing excluded volume we find the simulated correlation function of the\nRouse modes to deviate markedly from the predictions of phantom chain models.\nThis demonstrates that there are nonnegligible correlations along the chains in\na melt. These correlations can be taken into account by perturbation theory.\nOur simulation results are in good agreement with these new theoretical\npredictions.",
        "positive": "Emergence of Biaxiality in Nematic Liquid Crystals with Magnetic\n  Inclusions: Some Theoretical Insights: The biaxial phase in nematic liquid crystals has been elusive for several\ndecades after its prediction in the 1970s. A recent experimental breakthrough\nwas achieved by Liu et al. [PNAS 113, 10479 (2016)] in a liquid crystalline\nmedium with magnetic nanoparticles (MNPs). They exploited the different length\nscales of dipolar and magneto-nematic interactions to obtain an equilibrium\nstate where the magnetic moments are at an angle to the nematic director. This\ntilt introduces a second distinguished direction for orientational ordering or\nbiaxiality in the two-component system. Using coarse-grained Ginzburg-Landau\nfree energy models for the nematic and magnetic fields, we provide a\ntheoretical framework which allows for the manipulation of morphologies and\nquantitative estimates of biaxial order."
    },
    {
        "anchor": "Controlled self-aggregation of polymer-based nanoparticles employing\n  shear flow and magnetic fields: Star polymers with magnetically functionalized end groups are presented as a\nnovel polymeric system whose morphology, self-aggregation, and orientation can\neasily be tuned by exposing these macromolecules simultaneously to an external\nmagnetic field and to shear forces. Our investigations are based on a\nspecialized simulation technique which faithfully takes into account the\nhydrodynamic interactions of the surrounding, Newtonian solvent. We find that\nthe combination of magnetic field (including both strength and direction) and\nshear rate controls the mean number of magnetic clusters, which in turn is\nlargely responsible for the static and dynamic behavior. While some properties\nare similar to comparable non-magnetic star polymers, others exhibit novel\nphenomena; examples of the latter include the breakup and reorganization of the\nclusters beyond a critical shear rate, and a strong dependence of the\nefficiency with which shear rate is translated into whole-body rotations on the\ndirection of the magnetic field.",
        "positive": "Enumerating Designing Sequences in the HP Model: The hydrophobic/polar HP model on the square lattice has been widely used to\ninvestigate basics of protein folding. In the cases where all designing\nsequences (sequences with unique ground states) were enumerated without\nrestrictions on the number of contacts, the upper limit on the chain length N\nhas been 18-20 because of the rapid exponential growth of the numbers of\nconformations and sequences. We show how a few optimizations push this limit by\nabout 5 units. Based on these calculations, we study the statistical\ndistribution of hydrophobicity along designing sequences. We find that the\naverage number of hydrophobic and polar clumps along the chains is larger for\ndesigning sequences than for random ones, which is in agreement with earlier\nfindings for N up to 18 and with results for real enzymes. We also show that\nthis deviation from randomness disappears if the calculations are restricted to\nmaximally compact structures."
    },
    {
        "anchor": "Analysis of Two-State Folding Using Parabolic Approximation III:\n  Non-Arrhenius Kinetics of FBP28 WW Part-I: A model which treats the denatured and the native conformers as being\nconfined to harmonic Gibbs energy wells has been used to analyse the\nnon-Arrhenius behaviour of spontaneously folding fixed two-state systems. The\nresults demonstrate that when pressure and solvent are constant: (i) a\ntwo-state system is physically defined only for a finite temperature range;\n(ii)irrespective of the primary sequence, the 3-dimensional structure of the\nnative conformer, the residual structure in the denatured state, and the\nmagnitude of the folding and unfolding rate constants, the equilibrium\nstability of a two-state system is a maximum when its denatured conformers bury\nthe least amount of solvent accessible surface area (SASA) to reach the\nactivated state; (iii) the Gibbs barriers to folding and unfolding are not\nalways due to the incomplete compensation of the activation enthalpies and\nentropies; (iv) the difference in heat capacity between the reaction-states is\ndue to both the size of the solvent-shell and the noncovalent interactions; (v)\nthe position of the transition state ensemble along the reaction coordinate\n(RC) depends on the choice of the RC; and (vi) the atomic structure of the\ntransiently populated reaction-states cannot be inferred from\nperturbation-induced changes in their energetics.",
        "positive": "Hierarchies in Nucleation Transitions: We discuss the hierarchy of subphase transitions in first-order-like\nnucleation processes for an exemplified aggregation transition of\nheteropolymers. We perform an analysis of the microcanonical entropy, i.e., the\ndensity of states is considered as the central statistical system quantity\nsince it connects system-specific entropic and energetic information in a\nnatural and unique way."
    },
    {
        "anchor": "Electrostatic complexation of spheres and chains under elastic stress: We consider the complexation of highly charged semiflexible polyelectrolytes\nwith oppositely charged macroions. On the basis of scaling arguments we discuss\nhow the resulting complexes depend on the persistence length of the\npolyelectrolyte, the salt concentration, and the sizes and charges of the chain\nand the macroions. We study first the case of complexation with a single sphere\nand calculate the wrapping length of the chain. We then extend our\nconsiderations to complexes involving many wrapped spheres and study\ncooperative effects. The mechanical properties of such a complex under an\nexternal deformation are evaluated.",
        "positive": "Empty liquid state and re-entrant phase behavior of the patchy colloids\n  confined in the porous media: Patchy colloidal model with three and four equivalent patches, confined in\nthe attractive random porous media, undergo re-entrant gas-liquid phase\nseparation with the possibility for the liquid phase density to approach zero.\nThis unusual behavior is caused by an interplay between strong fluid-fluid\nbonding interactions and weak fluid-matrix attractions. At high temperature the\nshape of the phase diagram is determined by the attractive interaction between\nthe fluid particles; weak Yukawa attraction between fluid and obstacles only\nslightly enhances the fluid-fluid bonding. At low enough temperature the\nnetwork of the fluid particles is formed and the shape of the phase diagram\nbecomes defined by the Yukawa fluid-obstacle attraction. Due to this\ninteraction a layer of mutually bonded particles around the obstacles is formed\nand the network becomes fluid particles in the network is defined by a spatial\narrangement of the matrix particles. These features may open a new\npossibilities in making the equilibrium gels with the predefined nonuniform\ndistribution of the particles."
    },
    {
        "anchor": "Instability and front propagation in laser-tweezed lipid bilayer tubules: We study the mechanism of the `pearling' instability seen recently in\nexperiments on lipid tubules under a local applied laser intensity. We argue\nthat the correct boundary conditions are fixed chemical potentials, or surface\ntensions \\Sigma, at the laser spot and the reservoir in contact with the\ntubule. We support this with a microscopic picture which includes the intensity\nprofile of the laser beam, and show how this leads to a steady-state flow of\nlipid along the surface and gradients in the local lipid concentration and\nsurface tension (or chemical potential). This leads to a natural explanation\nfor front propagation and makes several predictions based on the tubule length.\nWhile most of the qualitative conclusions of previous studies remain the same,\nthe `ramped' control parameter (surface tension) implies several new\nqualitative results. We also explore some of the consequences of front\npropagation into a noisy (due to pre-existing thermal fluctuations) unstable\nmedium.",
        "positive": "Capillary migration of microdisks on curved interfaces: The capillary energy landscape for particles on curved fluid interfaces is\nstrongly influenced by the particle wetting conditions. Contact line pinning\nhas now been widely reported for colloidal particles, but its implications in\ncapillary interactions have not been addressed. Here, we present experiment and\nanalysis for disks with pinned contact lines on curved fluid interfaces. In\nexperiment, we study microdisk migration on a host interface with zero mean\ncurvature; the microdisks have contact lines pinned at their sharp edges and\nare sufficiently small that gravitational effects are negligible. The disks\nmigrate away from planar regions toward regions of steep curvature with\ncapillary energies inferred from the dissipation along particle trajectories\nwhich are linear in the deviatoric curvature. We derive the curvature capillary\nenergy for an interface with arbitrary curvature, and discuss each contribution\nto the expression. By adsorbing to a curved interface, a particle eliminates a\npatch of fluid interface and perturbs the surrounding interface shape. Analysis\npredicts that perfectly smooth, circular disks do not migrate, and that\nnanometric deviations from a planar circular, contact line, like those around a\nweakly roughened planar disk, will drive migration with linear dependence on\ndeviatoric curvature, in agreement with experiment."
    },
    {
        "anchor": "Density functional theory of freezing for soft interactions in two\n  dimensions: A density functional theory of two-dimensional freezing is presented for a\nsoft interaction potential that scales as inverse cube of particle distance.\nThis repulsive potential between parallel, induced dipoles is realized for\nparamagnetic colloids on an interface, which are additionally exposed to an\nexternal magnetic field. An extended modified weighted density approximation\nwhich includes correct triplet correlations in the liquid state is used. The\ntheoretical prediction of the freezing transition is in good agreement with\nexperimental and simulation data.",
        "positive": "Local chain ordering in amorphous polymer melts: Influence of chain\n  stiffness: Molecular dynamics simulation of a generic polymer model is applied to study\nmelts of polymers with different types of intrinsic stiffness. Important static\nobservables of the single chain such as gyration radius or persistence length\nare determined. Additionally we investigate the overall static melt structure\nincluding pair correlation function, structure function and orientational\ncorrelation function."
    },
    {
        "anchor": "Monopole Oscillations and Dampings in Boson and Fermion Mixture in the\n  Time-Dependent Gross-Pitaevskii and Vlasov Equations: We construct a dynamical model for the time evolution of the boson-fermion\ncoexistence system. The dynamics of bosons and fermions are formulated with the\ntime-dependent Gross-Pitaevsky equation and the Vlasov equation. We thus study\nthe monopole oscillation in the bose-fermi mixture. We find that large damping\nexists for fermion oscillations in the mixed system even at zero temperature.",
        "positive": "Mixed lipid bilayers with locally varying spontaneous curvature and\n  bending: A model of lipid bilayers made of a mixture of two lipids with different\naverage compositions on both leaflets, is developed. A Landau hamiltonian\ndescribing the lipid-lipid interactions on each leaflet, with two lipidic\nfields $\\psi_1$ and $\\psi_2$, is coupled to a Helfrich one, accounting for the\nmembrane elasticity, via both a local spontaneous curvature, which varies as\n$C_0+C_1(\\psi_1-\\psi_2)/2$, and a bending modulus equal to\n$\\kappa_0+\\kappa_1(\\psi_1+\\psi_2)/2$. This model allows us to define curved\npatches as membrane domains where the asymmetry in composition,\n$\\psi_1-\\psi_2$, is large, and thick and stiff patches where $\\psi_1+\\psi_2$ is\nlarge. These thick patches are good candidates for being lipidic rafts, as\nobserved in cell membranes, which are composed primarily of saturated lipids\nforming a liquid-ordered domain and are known to be thick and flat\nnano-domains. The lipid-lipid structure factors and correlation functions are\ncomputed for globally spherical membranes and planar ones. Phase diagrams are\nestablished, within a Gaussian approximation, showing the occurrence of two\ntypes of Structure Disordered phases, with correlations between either curved\nor thick patches, and an Ordered phase, corresponding to the divergence of the\nstructure factor at a finite wave vector. The varying bending modulus plays a\ncentral role for curved membranes, where the driving force $\\kappa_1C_0^2$ is\nbalanced by the line tension, to form raft domains of size ranging from 10 to\n100~nm. For planar membranes, raft domains emerge via the cross-correlation\nwith curved domains. A global picture emerges from curvature-induced\nmechanisms, described in the literature for planar membranes, to coupled\ncurvature- and bending-induced mechanisms in curved membranes forming a closed\nvesicle."
    },
    {
        "anchor": "Effective models for charge transport in DNA nanowires: The rapid progress in the field of molecular electronics has led to an\nincreasing interest on DNA oligomers as possible components of electronic\ncircuits at the nanoscale. For this, however, an understanding of charge\ntransfer and transport mechanisms in this molecule is required. Experiments\nshow that a large number of factors may influence the electronic properties of\nDNA. Though full first principle approaches are the ideal tool for a\ntheoretical characterization of the structural and electronic properties of\nDNA, the structural complexity of this molecule make these methods of limited\nuse. Consequently, model Hamiltonian approaches, which filter out single\nfactors influencing charge propagation in the double helix are highly valuable.\nIn this chapter, we give a review of different DNA models which are thought to\ncapture the influence of some of these factors. We will specifically focus on\nstatic and dynamic disorder.",
        "positive": "Calculation of Critical Nucleation Rates by the Persistent Embryo\n  Method: Application to Quasi Hard Sphere Models: We study crystal nucleation of the Weeks-Chandler-Andersen (WCA) model, using\nthe recently introduced Persistent Embryo Method (PEM). The method provides\ndetailed characterization of pre-critical, critical and post-critical nuclei,\nas well as nucleation rates that compare favorably with those obtained using\nother methods (umbrella sampling, forward flux sampling or seeding). We further\nmap our results to a hard sphere model allowing to compare with other existing\npredictions. Implications for experiments are also discussed."
    },
    {
        "anchor": "Slippery or sticky ! Control of wrinkling patterns by selective adhesion: Wrinkling patterns at the metallized surface of thin polymer films are shown\nto be sensitive to the sticky or slippery character of the polymer/substrate\ninterface (titanium coating, polystyrene film and coated silicon substrate).\nSelective prefered wrinkle orientation and amplitude are achieved. Existing\ntheoretical models are expanded to specific boundary conditions (adhesive vs\nslippery) and rationalize these observations.",
        "positive": "Spiral defect chaos in Rayleigh-B\u00e9nard convection: Asymptotic and\n  numerical studies of azimuthal flows induced by rotating spirals: Rotating spiral patterns in Rayleigh-B\\'enard convection are known to induce\nazimuthal flows, which raises the question of how different neighboring spirals\ninteract with each other in spiral chaos, and the role of hydrodynamics in this\nregime. Far from the core, we show that spiral rotations lead to an azimuthal\nbody force that is irrotational and of magnitude proportional to the\ntopological index of the spiral and its angular frequency. The force, although\nirrotational, cannot be included in the pressure field as it would lead to a\nnonphysical, multivalued pressure. We calculate the asymptotic dependence of\nthe resulting flow, and show that it leads to a logarithmic dependence of the\nazimuthal velocity on distance r away from the spiral core in the limit of\nnegligible damping coefficient. This solution dampens to approximately $1/r$\nwhen accounting for no-slip boundary conditions for the convection cell's\nplate. This flow component can provide additional hydrodynamic interactions\namong spirals including those observed in spiral defect chaos. We show that the\nanalytic prediction for the azimuthal velocity agrees with numerical results\nobtained from both two-dimensional generalized Swift-Hohenberg and\nthree-dimensional Boussinesq models, and find that the velocity field is\naffected by the size and charges of neighboring spirals. Numerically, we\nidentify a correlation between the appearance of spiral defect chaos and the\nbalancing between the mean-flow advection and the diffusive dynamics related to\nroll unwinding."
    },
    {
        "anchor": "Translational and rotational friction on a colloidal rod near a wall: We present particulate simulation results for translational and rotational\nfriction components of a shish-kebab model of a colloidal rod with aspect ratio\n(length over diameter) $L/D = 10$ in the presence of a planar hard wall.\nHydrodynamic interactions between rod and wall cause an overall enhancement of\nthe friction tensor components. We find that the friction enhancements to\nreasonable approximation scale inversely linear with the closest distance $d$\nbetween the rod surface and the wall, for $d$ in the range between $D/8$ and\n$L$. The dependence of the wall-induced friction on the angle $\\theta$ between\nthe long axis of the rod and the normal to the wall is studied and fitted with\nsimple polynomials in $\\cos \\theta$.",
        "positive": "Non-Newtonian granular hydrodynamics. What do the inelastic simple shear\n  flow and the elastic Fourier flow have in common?: We describe a special class of steady Couette flows in dilute granular gases\nadmitting a non-Newtonian hydrodynamic description for strong dissipation. The\nclass occurs when viscous heating exactly balances inelastic cooling, resulting\nin a uniform heat flux. It includes the Fourier flow of ordinary gases and the\nsimple or uniform shear flow (USF) of granular gases as special cases. The\nrheological functions have the same values as in the USF and generalized\nthermal conductivity coefficients can be identified. These points are confirmed\nby molecular dynamics simulations, Monte Carlo simulations of the Boltzmann\nequation, and analytical results from Grad's 13-moment method."
    },
    {
        "anchor": "Effect of Dibucaine on Phase Behavior of Ternary Liposome: We investigated the effect of Dibucaine hydrochloride (DC$\\cdot$HCl), one of\nthe local anesthetics, on phase behavior of ternary liposome composed of\ndioleoylphosphatidylcholine (DOPC), dipalmitoylphosphatidylcholine (DPPC), and\ncholesterol (Chol). The large DOPC/DPPC/Chol liposome, that is directly\nobservable by optical microscope, is commonly known to be laterally separated\ninto liquid-ordered (Lo) phase (raft-like domain) and liquid-disordered (Ld)\nphase under certain conditions and is useful for study of lipid-raft-like\ndomains as a simple model system. In order to confirm the effect of\nDC$\\cdot$HCl on a miscibility transition temperature, $T_{\\rm c}$, of the\nternary liposome, we observed the liposomes with three concentrations, 0, 0.05,\nand 0.2~mM, of DC$\\cdot$HCl at various temperatures. In addition, we calculated\nthe angle-averaged two-dimensional autocorrelation (2D-AC) functions in order\nto quantify the phase behavior. The results of these observations and\ncalculations revealed that the DC$\\cdot$HCl molecules induce the reduction of\n$T_{\\rm c}$ of the ternary liposome. Furthermore, we calculated the circularity\nof Lo domain in order to confirm the change in the line tension of the Lo/Ld\nphase boundary and revealed that the insertion of the DC molecules induces the\nreduction of line tension. In terms of the critical phenomena, we conclude that\nthe insertion of the DC molecules induces the reduction of the $T_{\\rm c}$ of\nthe ternary liposome due to reduction of line tension. This suggests that the\nDC molecules may disturb function of ion channels via affecting the lipid\nbilayers which surround ion channels.",
        "positive": "Scaling dependence on time and distance in nonlinear fractional\n  diffusion equations and possible applications to the water transport in soils: Recently, fractional derivatives have been employed to analyze various\nsystems in engineering, physics, finance and hidrology. For instance, they have\nbeen used to investigate anomalous diffusion processes which are present in\ndifferent physical systems like: amorphous semicondutors, polymers, composite\nheterogeneous films and porous media. They have also been used to calculate the\nheat load intensity change in blast furnace walls, to solve problems of control\ntheory \\ and dynamic problems of linear and nonlinear hereditary mechanics of\nsolids. In this work, we investigate the scaling properties related to the\nnonlinear fractional diffusion equations and indicate the possibilities to the\napplications of these equations to simulate the water transport in unsaturated\nsoils. Usually, the water transport in soils with anomalous diffusion, the\ndependence of concentration on time and distance may be expressed in term of a\nsingle variable given by $\\lambda_q = x/t^{q}.$ In particular, for $q=1/2$ the\nsystems obey Fick's law and Richards' equation for water transport. We show\nthat a generalization of Richards' equation via fractional approach can\nincorporate the above property."
    },
    {
        "anchor": "Dynamical Transitions of Supercooled Water in Graphene oxide Nanopores:\n  Influence of Surface Hydrophobicity: Molecular dynamics simulations are carried out to explore the dynamical\ncrossover phenomenon in strongly confined and mildly supercooled water in\ngraphene oxide nanopores. In contrast to studies where confinement is used to\nstudy the properties of bulk water, we are interested in the dynamical\ntransitions for strongly confined water in the absence of any bulk-like water.\nThe influence of the physicochemical nature of the graphene oxide surface on\nthe dynamical transitions is investigated by varying the extent of\nhydrophobicity on the confining surfaces placed at an inter-surface separation\nof 10 \\AA\\,. All dynamical quantities show a typical slowing down as the\ntemperature is lowered from 298 to 200 K; however, the nature of the transition\nis a distinct function of the surface type. Water confined between surfaces\nconsisting of alternating hydrophilic and hydrophobic regions exhibit a\nstrong-to-strong dynamical transition in the diffusion coefficients and\nrotational relaxation times at a crossover temperature of 237 K and show a\nfragile-to-strong transition in the $\\alpha$-relaxation time at 238 K. The\nobserved crossover temperature is much higher than the freezing point of the\nSPC/E water model used in this study, indicating that these dynamical\ntransitions can occur with mild supercooling under strong confinement in the\nabsence of bulk-like water. In contrast, water confined in hydrophilic pore\nshows a single Arrhenius energy barrier over the entire temperature range. Our\nresults indicate that in addition to confinement, the nature of the surface can\nplay a critical role in determining the dynamical transitions for water upon\nsupercooling.",
        "positive": "Fluid-bicontinuous emulsions stabilized by colloidal particles: Using controlled spinodal decomposition, we have created a fluid-bicontinuous\nstructure stabilized by colloidal particles. We present confocal microscopy\nstudies of these structures and their variation with kinetic pathway. Our\nstudies reveal a rigid multilayer of colloidal particles jammed at the\ninterface which prevents the liquids demixing for many hours. The arrangement\nof two-fluid domains, interpenetrating on the meso-scale, could be useful as a\nmicroreaction medium."
    },
    {
        "anchor": "Logarithmic Relaxation in Glass-Forming Systems: Within the mode-coupling theory for ideal glass transitions, an analysis for\nthe correlation functions of glass-forming systems for states near higher-order\nglass-transition singularities is presented. It is shown that the solutions of\nthe equations of motion can be asymptotically expanded in polynomials of the\nlogarithm of time t. In leading order, an ln(t)-law is obtained, and the\nleading corrections are given by a fourth-order polynomial. The correlators\ninterpolate between three scenarios. First, there are planes in parameter space\nwhere the dominant corrections to the ln(t)-law vanish, so that the logarithmic\ndecay governs the structural relaxation process. Second, the dynamics due to\nthe higher-order singularity can describe the initial and intermediate part of\nthe alpha-process thereby reducing the range of validity of von Schweidler's\nlaw and leading to strong alpha-relaxation stretching. Third, the ln(t)-law can\nreplace the critical decay law of the beta-process leading to a particularly\nlarge crossover interval between the end of the transient and the beginning of\nthe alpha-process. This may lead to susceptibility spectra below the band of\nmicroscopic excitations exhibiting two peaks. Typical results of the theory are\ndemonstrated for models dealing with one and two correlation functions.",
        "positive": "Turning catalytically active pores into active pumps: We develop a semi-analytical model of self-diffusioosmotic transport in\nactive pores, which includes advective transport and the inverse chemical\nreaction which consumes solute. In previous work (Phys. Rev. Lett. 129, 188003,\n2022), we have demonstrated the existence of a spontaneous symmetry breaking in\nfore-aft symmetric pores that enables them to function as a micropump. We now\nshow that this pumping transition is controlled by three timescales. Two\ntimescales characterize advective and diffusive transport. The third timescale\ncorresponds to how long a solute molecule resides in the pore before being\nconsumed. Introducing asymmetry to the pore (either via the shape or the\ncatalytic coating) reveals a second type of advection-enabled transitions. In\nasymmetric pores, the flow rate exhibits discontinuous jumps and hysteresis\nloops upon tuning the parameters that control the asymmetry. This work\ndemonstrates the interconnected roles of shape and catalytic patterning in the\ndynamics of active pores, and shows how to design a pump for optimum\nperformance."
    },
    {
        "anchor": "Gas bubble dynamics in soft materials: Epstein and Plesset's seminal work on the rate of gas bubble dissolution and\ngrowth in a simple liquid is generalized to render it applicable to a gas\nbubble embedded in a soft elastic medium. Both the underlying diffusion\nequation and the expression for the gas bubble pressure were modified to allow\nfor the non-zero shear modulus of the elastic medium. The extension of the\ndiffusion equation results in a trivial shift (by an additive constant) in the\nvalue of the diffusion coefficient, and does not change the form of the rate\nequations. But the use of a Generalized Young-Laplace equation for the bubble\npressure resulted in significant differences on the dynamics of bubble\ndissolution and growth, relative to a simple liquid medium. Depending on\nwhether the salient parameters (solute concentration, initial bubble radius,\nsurface tension, and shear modulus) lead to bubble growth or dissolution, the\neffect of allowing for a non-zero shear modulus in the Generalized\nYoung-Laplace equation is to speed up the rate of bubble growth, or to reduce\nthe rate of bubble dissolution, respectively. The relation to previous work on\nvisco-elastic materials is discussed, as is the connection of this work to the\nproblem of Decompression Sickness (specifically, \"the bends\"). Examples of\ntissues to which our expressions can be applied are provided. Also, a new\nphenomenon is predicted whereby, for some parameter values, a bubble can be\nmetastable and persist for long times, or it may grow, when embedded in a\nhomogeneous under-saturated soft elastic medium.",
        "positive": "Spectral Signatures of the Diffusional Anomaly in Water: Analysis of power spectrum profiles for various tagged particle quantities in\nbulk SPC/E water is used to demonstrate that variations in mobility associated\nwith the diffusional anomaly are mirrored in the exponent of the \\onebyf\\\nregion. Monitoring of \\onebyf behaviour is shown to be a simple and direct\nmethod for linking phenomena on three distinctive length and time scales: the\nlocal molecular environment, hydrogen bond network reorganisations and the\ndiffusivity. The results indicate that experimental studies of supercooled\nwater to probe the density dependence of $1/f^\\alpha$ spectral features, or\nequivalent stretched exponential behaviour in time-correlation functions, will\nbe of interest."
    },
    {
        "anchor": "Stability and buckling of flat circular configurations of closed,\n  intrinsically nonrectilinear filaments spanned by fluid films: We explore how the stability and buckling behavior of a flexible but\ninextensible loop spanned by a liquid film in a flat circular configuration is\ninfluenced by the intrinsic shape of the fiber from which the loop is made.",
        "positive": "Structure--property relationships of cell clusters in biotissues: 2D\n  analysis: To insight the relationships between the self-organizing structures of cells,\nsuch as the cell clusters, and the properties of biotissues is helpful in\nrevealing the function and designing biomaterial. Traditional random foam model\nneglects several important details of the frameworks of cell clusters, in this\nstudy we use a more complete model, cell adhesion model, to investigate the\nmechanical and morphological properties of the two-dimensional (2D) dry foams\ncomposed by cells. Supposing these structures are formed due to adhesion\nbetween cells, the equilibrium formations result from the minimum of the free\nenergy. The equilibrium shape equations for high symmetrical structures without\nthe volume constraint are derived, and the analytical results of the\ncorresponding mechanical parameters, such as the Young's modulus, bulk modulus\nand failure strength, are obtained. Numerical simulation method is applied to\nstudy the complex shapes with the volume constraint and several stable\nmulticellular structures are obtained. Symmetry-breaking due to the volume\nchange is founded and typical periodic shapes and the corresponding phase\ntransformations are explored. Our study provides a potential method to connect\nthe microstructure with the macro-mechanical parameters of biotissues. The\nresults also are helpful to understand the physical mechanism of how the\nstructures of biotissues are formed."
    },
    {
        "anchor": "Geometry-driven folding of a floating annular sheet: Predicting the large-amplitude deformations of thin elastic sheets is\ndifficult due to the complications of self-contact, geometric nonlinearities,\nand a multitude of low-lying energy states. We study a simple two-dimensional\nsetting where an annular polymer sheet floating on an air-water interface is\nsubjected to different tensions on the inner and outer rims. The sheet folds\nand wrinkles into many distinct morphologies that break axisymmetry. These\nstates can be understood within a recent geometric approach for determining the\ngross shape of extremely bendable yet inextensible sheets by extremizing an\nappropriate area functional. Our analysis explains the remarkable feature that\nthe observed buckling transitions between wrinkled and folded shapes are\ninsensitive to the bending rigidity of the sheet.",
        "positive": "Computational method for highly-constrained molecular dynamics of rigid\n  bodies: coarse-grained simulation of auxetic two-dimensional protein crystals: The increasing number of protein-based metamaterials demands reliable and\nefficient theoretical and computational methods to study the physicochemical\nproperties they may display. In this regard, we develop a simulation strategy\nbased on Molecular Dynamics (MD) that addresses the geometric degrees of\nfreedom of an auxetic two-dimensional protein crystal. This model consists of a\nnetwork of impenetrable rigid squares linked through massless rigid rods. Our\nMD methodology extends the well-known protocols SHAKE and RATTLE to include\nhighly non-linear holonomic and non-holonomic constraints, with emphasis on\ncollision detection and response between anisotropic rigid bodies. The\npresented method enables the simulation of long-time dynamics with reasonably\nlarge time-steps. The data extracted from the simulations allow the\ncharacterization of the dynamical correlations featured by the protein\nsubunits, which show a persistent motional interdependence across the array. On\nthe other hand, non-holonomic constraints (collisions between subunits)\nincrease the number of inhomogeneous deformations of the network, thus driving\nit away from an isotropic response. Our work provides the first long-timescale\nsimulation of the dynamics of protein crystals and offers insights into\npromising mechanical properties afforded by these materials."
    },
    {
        "anchor": "Grain-size dependence of water retention in a model aggregated soil: We experimentally examined the amount of water retention in a model soil\ncomposed of aggregated glass beads. The model soil was characterized by two\nsize parameters: size of aggregates $D$ and size of monomer particles\n(composing aggregates) $d$. In the experiment, water was sprinkled on the\nmodel-soil system that has an open top surface and drainable sieve bottom. When\nthe sprinkled water amount exceeded a threshold (retainable limit), draining\nflux balanced with the sprinkled flux. The weight variations of retained and\ndrained water were measured to confirm this balanced (steady) state and\nquantify the retained water. We defined the weight of the retained water in\nthis steady state as $W_0$ and examined the relationship among $W_0$, $d$ and\n$D$. As a result, it was revealed that $W_0$ increases as $d$ decreases simply\ndue to the capillary effects. Regarding $D$ dependence, it turned out that\n$W_0$ becomes the maximum around $D\\simeq 500$~$\\mu$m. The value of $D$\nmaximizing water retention is determined by the void formation due to the\naggregated structure, capillary effect, and gravity.",
        "positive": "A novel proof of the DFT formula for the interatomic force field of\n  Molecular Dynamics: We give a novel and simple proof of the DFT expression for the interatomic\nforce field that drives the motion of atoms in classical Molecular Dynamics,\nbased on the observation that the ground state electronic energy, seen as a\nfunctional of the external potential, is the Legendre transform of the\nHohenberg-Kohn functional, which in turn is a functional of the electronic\ndensity. We show in this way that the so-called Hellmann-Feynman analytical\nformula, currently used in numerical simulations, actually provides the exact\nexpression of the interatomic force."
    },
    {
        "anchor": "Influence of conformational fluctuations on enzymatic activity:\n  modelling the functional motion of beta-secretase: Considerable insight into the functional activity of proteins and enzymes can\nbe obtained by studying the low-energy conformational distortions that the\nbiopolymer can sustain. We carry out the characterization of these large scale\nstructural changes for a protein of considerable pharmaceutical interest, the\nhuman $\\beta$-secretase. Starting from the crystallographic structure of the\nprotein, we use the recently introduced beta-Gaussian model to identify, with\nnegligible computational expenditure, the most significant distortion occurring\nin thermal equilibrium and the associated time scales. The application of this\nstrategy allows to gain considerable insight into the putative functional\nmovements and, furthermore, helps to identify a handful of key regions in the\nprotein which have an important mechanical influence on the enzymatic activity\ndespite being spatially distant from the active site. The results obtained\nwithin the Gaussian model are validated through an extensive comparison against\nan all-atom Molecular Dynamics simulation.",
        "positive": "Rolling and ageing in T-ramp soft adhesion: Immediately before adsorption to a horizontal substrate, sinking\npolymer-coated colloids can undergo a complex sequence of landing, jumping,\ncrawling and rolling events. Using video tracking we studied the soft adhesion\nto a horizontal flat plate of micron-size colloids coated by a controlled molar\nfraction $f$ of the polymer PLL-g-PNIPAM which is temperature sensitive. We\nramp the temperature from below to above $T_c=32\\pm 1^{\\circ}$C, at which the\nPNIPAM polymer undergoes a transition triggering attractive interaction between\nmicroparticles and surface. The adsorption rate, the effective in-plane ($x-y$)\ndiffusion constant and the average residence time distribution over $z$ were\nextracted from the Brownian motion records during last seconds before\nimmobilisation. Experimental data are understood within a rate-equations based\nmodel that includes ageing effects and includes three populations: the\nuntethered, the rolling and the arrested colloids. We show that pre-adsorption\ndynamics casts analyze a characteristic scaling function $\\alpha (f)$\nproportional to the number of available PNIPAM patches met by soft contact\nduring Brownian rolling. In particular, the increase of in-plane diffusivity\nwith increasing $f$ is understood: the stickiest particles have the shortest\nrolling regime prior to arrest, so that their motion is dominated by untethered\nphase."
    },
    {
        "anchor": "Critical effects and scaling at meniscus osculation transitions: We propose a simple scaling theory describing critical effects at rounded\nmeniscus osculation transitions which occur when the Laplace radius of a\ncondensed macroscopic drop of liquid coincides with the local radius of\ncurvature $R_w$ in a confining parabolic geometry. We argue that the exponent\n$\\beta_{\\rm osc}$ characterising the scale of the interfacial height $\\ell_0\n\\propto R_w^{\\beta_{\\rm osc}}$ at osculation, for large $R_w$, falls into two\nregimes representing fluctuation-dominated and mean-field like behaviour,\nrespectively. These two regimes are separated by an upper critical dimension,\nwhich is determined here explicitly and which depends on the range of the\nintermolecular forces. In the fluctuation-dominated regime, representing the\nuniversality class of systems with short-ranged forces, the exponent is related\nto the value of the interfacial wandering exponent $\\zeta$ by $\\beta_{\\rm\nosc}=3\\zeta/(4-\\zeta)$. In contrast, in the mean-field regime, which has not\nbeen previously identified, and which occurs for systems with longer ranged\nforces (and higher dimensions), the exponent $\\beta_{\\rm osc}$ takes the same\nvalue as the exponent $\\beta_s^{\\rm co}$ for complete wetting which is\ndetermined directly by the intermolecular forces. The prediction $\\beta_{\\rm\nosc}=3/7$ in $d=2$ for systems with short-ranged forces (corresponding to\n$\\zeta=1/2$) is confirmed using an interfacial Hamiltonian model which\ndetermines the exact scaling form for the decay of the interfacial height\nprobability distribution function. A numerical study in $d=3$, based on a\nmicroscopic model Density Functional Theory, determines that $\\beta_{\\rm osc}\n\\approx \\beta_s^{\\rm co}\\approx 0.326$ close to the predicted value $1/3$\nappropriate to the mean-field regime for dispersion forces.",
        "positive": "A path integral approach for the colloidal glass transition based on an\n  analogy with the $\u03bb$-transition in liquid helium: We describe a model for the colloidal glass transition that is based on\nFeynman's theory for the $\\lambda$-transition in liquid helium. Our model\nessentially counts the number of configurations of dynamic loops, strings or\nclusters of different sizes, and determines the glass transition volume\nfraction $\\phi_{g}$ from the distribution of these heterogeneities. Since\nconfinement restricts the available number of configurations for these loops,\nstrings and clusters, its effect on $\\phi_{g}$ can also be calculated in a\nrelatively straightforward manner."
    },
    {
        "anchor": "Dynamically Correlated Region in Sheared Colloidal Glasses Revealed by\n  Neutron Scattering: The microscopic deformation mechanism of charged colloidal glasses with\nextended-range interactions under shear is investigated by in-situ small-angle\nneutron scattering, and a dynamically correlated region (DCR) is identified.\nThis short-lived region provides the resistance to the configurational\nrearrangement imposed by the external deformation, as evidenced by the\nevolution of the size of DCR in the shear thinning regime and the quantitative\nagreement between the local stress sustained by DCR and the macroscopic stress\nfrom rheological measurements at low and mediate shear rates. This finding\nsuggests that DCR is an important quantity for microscopically addressing the\nflow and deformation behavior of strongly interacting colloids.",
        "positive": "Volume Determination of Globular Proteins by Molecular Dynamics: Molecular dynamics simulations of myoglobin and aspartate aminotransferase,\nwith explicit solvent, are shown to accurately reproduce the experimentally\nmeasured molar volumes. Single amino-acid substitution at VAL39 of aspartate\naminotransferase is known to produce large volumetric changes in the enzyme,\nand this effect is demonstrated in simulation as well. This molecular dynamics\napproach, while more computationally expensive that extant computational\nmethods of determining the apparent volume of biological systems, is quite\nfeasible with modern computer hardware and is shown to yield accurate\nvolumetric data with as little as several nanoseconds of dynamics."
    },
    {
        "anchor": "On the effect of the thermal gas component to the stability of vortices\n  in trapped Bose-Einstein condensates: We study the stability of vortices in trapped single-component Bose-Einstein\ncondensates within self-consistent mean-field theories--especially we consider\nthe Hartree-Fock-Bogoliubov-Popov theory and its recently proposed gapless\nextensions. It is shown that for sufficiently repulsively interacting systems\nthe anomalous negative-energy modes related to vortex instabilities are lifted\nto positive energies due to partial filling of the vortex core with\nnoncondensed gas. Such a behavior implies that within these theories the vortex\nstates are eventually stable against transfer of condensate matter to the\nanomalous core modes. This self-stabilization of vortices, shown to occur under\nvery general circumstances, is contrasted to the predictions of the\nnon-self-consistent Bogoliubov approximation, which is known to exhibit\nanomalous modes for all vortex configurations and thus implying instability of\nthese states. In addition, the shortcomings of these approximations in\ndescribing the properties of vortices are analysed, and the need of a\nself-consistent theory taking properly into account the coupled dynamics of the\ncondensate and the noncondensate atoms is emphasized.",
        "positive": "Programmed buckling by controlled lateral swelling in a thin elastic\n  sheet: Recent experiments have imposed controlled swelling patterns on thin polymer\nfilms, which subsequently buckle into three-dimensional shapes. We develop a\nsolution to the design problem suggested by such systems, namely, if and how\none can generate particular three-dimensional shapes from thin elastic sheets\nby mere imposition of a two-dimensional pattern of locally isotropic growth.\nNot every shape is possible. Several types of obstruction can arise, some of\nwhich depend on the sheet thickness. We provide some examples using the\naxisymmetric form of the problem, which is analytically tractable."
    },
    {
        "anchor": "Deformations of an active liquid droplet: A fluid droplet in general deforms, if subject to active driving, such as a\nfinite slip velocity or active tractions on its interface. We show that these\ndeformations and their dynamics can be computed analytically in a perturbation\ntheory in the inverse surface tension using an approach based on vector\nspherical harmonics. In lowest order, the deformation is of first order, yet it\naffects the flow fields inside and outside of the droplet in zeroth order.\nHence a correct description of the flow has to allow for shape fluctuations,\neven in the limit of large surface tension.",
        "positive": "Drag force in immersed granular materials: We investigate the drag forces acting on large objects moving through a\ngranular packing immersed in water. In this aim, we conducted uplift\nexperiments involving pulling out horizontal plates at a prescribed velocity\nvertically. During these tests, we observed that the drag force reaches to peak\nat a low displacement and then decays. Results show that the peak drag force\nstrongly increases with the velocity and depends on the plate size and grain\ndiameter. We identify empirical scaling laws for these properties and introduce\na Darcy-flow mechanism that can explain them. Furthermore, we conducted tests\ninvolving suddenly stopping the motion of the plate, which evidenced a\nprogressive relaxation of the drag force in time. We discuss how a\nvisco-elasto-plastic mechanical analogue can reproduce these dynamics. These\nresults and analyses highlight fundamental differences in drag force between\ndry and immersed granular materials."
    },
    {
        "anchor": "Comment on Influence of non-conservative optical forces on the dynamics\n  of optically trapped colloidal spheres: The fountain of probability,\n  arXiv:0804.0730v1: We demonstrate that the data presented in the manuscript by Y. Roichman et\nal. are not sufficient to show that the circulation of a trapped particle\nexists in a static optical trap.",
        "positive": "Magnetorheological effect in elastomers containing uniaxial\n  ferromagnetic particles: The description of the collective magnetorheological effect induced by\nmagnetic field in magnetoactive elastomers is proposed. The condition of\nconsistency is used between magnetic and mechanic momenta of forces exerted on\nmagnetically uniaxial ferromagnetic particles in elastomer at their\nmagnetization. The study shows that even in the case of small concentration of\nparticles, the value of magnetically-induced shear can be anomalously large,\nreaching up to tens of percent. The deformation of magnetoactive elastomer can\nevolve critically, as a second-order phase transition, if magnetic field is\naligned along the easy axis of particles."
    },
    {
        "anchor": "Micrometric particles twodimensional self-assembly during drying of\n  liquid film: We computed the self-organisation process of a monodisperse collection of\nspherical micrometric particles trapped in a two-dimensional (2D) thin liquid\nfilm isothermally dried on a chemically inert substrate. The substrate is\neither flat or indented to create linear stripes on its surface. The numerical\nresults are illustrated and discussed in the light of experimental ones\nobtained from the drying of diamond particles water based suspension ($d_{50} =\n10 \\mu m$) on a glass substrate. The drying of the suspension on a flat\nsubstrate leads to the formation of linear patterns and small clusters of\nmicrometric particles distributed over the whole surface of the substrate,\nwhereas the drying of the suspension on a indented substrate leads to the\naggregation of the particles along one side of the stripe which has a higher\nroughness than the other side of the stripe. This is an easy experimental way\nto obtain colloidal selforganized patterns.",
        "positive": "Tuning the critical solution temperature of polymers by copolymerization: We study statistical copolymerization effects on the upper critical solution\ntemperature (CST) of generic homopolymers by means of coarse-grained Langevin\ndynamics computer simulations and mean-field theory. Our systematic\ninvestigation reveals that the CST can change monotonically or\nnon-monotonically with copolymerization, as observed in experimental studies,\ndepending on the degree of non-additivity of the monomer (A-B)\ncross-interactions. The simulation findings are confirmed and qualitatively\nexplained by a combination of a two-component Flory-de Gennes model for polymer\ncollapse and a simple thermodynamic expansion approach. Our findings provide\nsome rationale behind the effects of copolymerization and may be helpful for\ntuning CST behavior of polymers in soft material design."
    },
    {
        "anchor": "A simplified theory of \"stickiness\" due to electroadhesion between rough\n  surfaces: Building on theories of Persson, we derive a simpler theory for\nelectroadhesion between rough surfaces using BAM (Bearing Area Model) of\nCiavarella, or previous ideas by Persson and Tosatti. Rather surprisingly, in\nterms of stickiness, we obtain very simple and similar results for pure power\nlaw power spectrum density (PSD), confirming stickiness to be mainly dependent\non macroscopic quantities. We define a new dimensionless parameter for\nelectroadhesive stickiness.",
        "positive": "Self-assembly of colloid-cholesteric composites provides a possible\n  route to switchable optical materials: Colloidal particles dispersed in liquid crystals can form new materials with\ntunable elastic and electro-optic properties. In a periodic `blue phase' host,\nparticles should template into colloidal crystals with potential uses in\nphotonics, metamaterials, and transformational optics. Here we show by computer\nsimulation that colloid/cholesteric mixtures can give rise to regular crystals,\nglasses, percolating gels, isolated clusters, twisted rings and undulating\ncolloidal ropes. This structure can be tuned via particle concentration, and by\nvarying the surface interactions of the cholesteric host with both the\nparticles and confining walls. Many of these new materials are metastable: two\nor more structures can arise under identical thermodynamic conditions. The\nobserved structure depends not only on the formulation protocol, but also on\nthe history of an applied electric field. This new class of soft materials\nshould thus be relevant to design of switchable, multistable devices for\noptical technologies such as smart glass and e-paper."
    },
    {
        "anchor": "Navier-Stokes hydrodynamics in a granular gas fluidized by a non-uniform\n  stochastic field: We show a case of steady flow in a granular gas that, for small shear rates,\nis accurately described by Navier-Stokes hydrodynamics, even for high\ninelasticity. The (low density) granular gas is composed of identical inelastic\nspheres and is fluidized by a temperature field produced by a stochastic volume\nforce plus thermal walls. We prove that the theoretical Navier-Stokes transport\ncoefficients exhibit good agreement with numerical solutions of the\ncorresponding the kinetic equation (direct simulation Monte Carlo method) in\nthe steady state.",
        "positive": "Crystallization kinetics of colloidal model suspensions: recent\n  achievements and new perspectives: Colloidal model systems allow studying crystallization kinetics under fairly\nideal conditions with rather well characterized pair interactions and minimized\nexternal influences. In complementary approaches therefore experiment, analytic\ntheory and simulation have been employed to study colloidal solidification in\ngreat detail. These studies were based on advanced optical methods, careful\nsystem characterization and sophisticated numerical methods. Both the effects\nof the type, strength and range of the pair-interaction between the colloidal\nparticles and those of the colloid-specific polydispersity were addressed in a\nquantitative way. Key parameters of crystallization were derived and compared\nto those of metal systems. These systematic investigations significantly\ncontributed to an enhanced understanding of the crystallization processes in\ngeneral. Further, new fundamental questions have arisen and (partially) been\nsolved over the last decade including e.g. a two step nucleation mechanism in\nhomogeneous nucleation, choice of the crystallization pathway or the subtle\ninterplay of boundary conditions in heterogeneous nucleation. On the other\nside, via the application of both gradients and external fields the competition\nbetween different nucleation and growth modes can be controlled and the\nresulting micro-structure be influenced. The present review attempts an account\nof the interesting developments occurred since the turn of the millennium and\nan identification of important novel trends with particular focus on\nexperimental aspects."
    },
    {
        "anchor": "The stability of the 18-fold symmetry soft-matter quasicrystals: Following our previous work this article reports a study on the stability of\nthe 18-fold symmetry soft-matter quasicrystals, in which the extended free\nenergy is a basis for the analysis that is similar to the study of the 12-fold\nsymmetry quasicrystals. Due to the differences in structure between these two\nkinds of quasicrystals, their stabilities present some different characters to\neach other. Because there were no any results of the stability of 18-fold\nsymmetry soft-matter quasicrystals reported yet, perhaps the present work is\nthe first probe on the topic.",
        "positive": "Reciprocal theorem for linear poro-viscoelastic materials: In studying the transport of particles and inclusions in multi-phase systems\nwe are often interested in integrated quantities such as the total force and\nthe net velocity of the particles. Here, we derive a reciprocal formulation for\nlinear poro-viscoelastic (PVE) materials, which are composed of a linear\ncompressible viscoelastic phase, i.e. the network phase, permeated by a viscous\nfluid. As an application of the reciprocal theorem, we analytically calculate\nthe time-dependent net force on a rigid stationary sphere in response to\npoint-forces applied to the elastic network and Newtonian fluid phases of a PVE\nmaterial. We show that the net force on the sphere in response to a point-force\nin the fluid phase evolves over timescales that are independent of the distance\nof the point-force to the sphere; in comparison, when the point-force is\napplied to the network phase the timescale for force development becomes\ndistance-dependent. We discuss how in both cases these relaxation times are\nrelated to the physical timescales that are determined by mechanical properties\nof both phases -- such as the network's Poisson ratio, permeability and shear\nmodules, and the fluid viscosity -- as well as geometric factors, including the\nsize of the spherical inclusion and its distance from point-forces. The\nreciprocal theorem presented here can be applied to a wide range of problems\ninvolving the transport of cells, organelles and condensates in biological\nsystems composed of filamentous networks permeated by viscous fluids."
    },
    {
        "anchor": "Phase Incremented Echo Train Acquisition applied to Magnetic Resonance\n  Pore Imaging: Efficient phase cycling schemes remain a challenge for NMR techniques if the\npulse sequences involve a large number of rf-pulses. Especially complex is the\nCarr Purcell Meiboom Gill (CPMG) pulse sequence where the number of rf-pulses\ncan range from hundreds to several thousands. Our recent implementation of\nMagnetic Resonance Pore Imaging (MRPI) is based on a CPMG rf-pulse sequence in\norder to refocus the effect of internal gradients inherent in porous media.\nWhile the spin dynamics for spin-$1/2$ systems in CPMG like experiments are\nwell understood it is still not straight forward to separate the desired\npathway from the spectrum of unwanted coherence pathways. In this contribution\nwe apply Phase Incremented Echo Train Acquisition (PIETA) to MRPI. We show how\nPIETA offers a convenient way to implement a working phase cycling scheme and\nhow it allows one to gain deeper insights into the amplitudes of undesired\npathways.",
        "positive": "\"Pseudoisomorphs\" in liquids with intramolecular degrees of freedom: Computer simulations show that liquids of molecules with harmonic\nintramolecular bonds may have \"pseudoisomorphic\" lines of approximately\ninvariant dynamics in the thermodynamic phase diagram. We demonstrate that\nthese lines can be identified by requiring scale invariance of the\ninherent-structure reduced-unit low-frequency vibrational spectrum evaluated\nfor a single equilibrium configuration. This rationalizes why excess-entropy\nscaling, density scaling, and isochronal superposition apply for many liquids\nwith internal degrees of freedom."
    },
    {
        "anchor": "Biased transport of elastic cytoskeletal filaments with alternating\n  polarities by molecular motors: We present a simple model for the bidirectional dynamics of actin bundles\nwith alternating polarities in gliding assays with non-processive myosin\nmotors. In the model, the bundle is represented as an elastic chain consisting\nof monomers with positive and negative polarities. The motion of the bundle is\ninduced by the pulling forces of the underlying motors which stochastically\nattach to the monomers and, depending on the polarity of the monomers, pull\nthem in the right or left direction. We demonstrate that perfectly a-polar\nchains consisting of equal numbers of monomers with positive and negative\npolarities may exhibit biased bidirectional motion with non-zero drift. This\neffect is attributed to the elastic tension developed in the chain due to the\naction of the myosin motors. We also show that as a result of this tension, the\nattachment probability of the motors is greatly reduced and becomes strongly\ndependent on the length of the chain. These surprising effects point to the\nnecessity of considering the elasticity of the cytoskeleton in theoretical\nstudies of cooperative dynamics of molecular motors.",
        "positive": "Self-assembly of Colloids with Competing Interactions Confined in\n  Spheres: At low temperatures, colloidal particles with short-range attractive and\nlong-range repulsive interactions can form various periodic microphases in\nbulk.In this paper, we investigate the self-assembly behaviour of colloids with\ncompeting interactions under spherical confinement by conducting molecular\ndynamics simulations. We find that the cluster, mixture, cylindrical,\nperforated lamellar and lamellar structures can be obtained, but the details of\nthe ordered structures are different from those in bulk systems. Interestingly,\nthe system tends to form more perforated structures when confined in smaller\nspheres. The mechanism behind this phenomenon is the relationship between the\nenergy of the ordered structures and the bending of the confinement wall, which\nis different from the mechanism in copolymer systems."
    },
    {
        "anchor": "Size scaling of static friction: Sliding friction across a thin soft lubricant film typically occurs by\nstick-slip, the lubricant fully solidifying at stick, yielding and flowing at\nslip. The static friction force per unit area preceding slip is known from\nmolecular dynamics (MD) simulations to decrease with increasing contact area.\nThat makes the large-size fate of stick-slip unclear and unknown; its possible\nvanishing is important as it would herald smooth sliding with a dramatic drop\nof kinetic friction at large size. Here we formulate a scaling law of the\nstatic friction force, which for a soft lubricant is predicted to decrease as\nf_m + \\Delta f /A^gamma for increasing contact area A, with gamma>0. Our main\nfinding is that the value of f_m, controlling the survival of stick-slip at\nlarge size, can be evaluated by simulations of comparably small size. MD\nsimulations of soft lubricant sliding are presented, which verify this theory.",
        "positive": "Phase Separation of Rigid-Rod Suspensions in Shear Flow: We analyze the behavior of a suspension of rigid rod-like particles in shear\nflow using a modified version of the Doi model, and construct diagrams for\nphase coexistence under conditions of constant imposed stress and constant\nimposed strain rate, among paranematic, flow-aligning nematic, and log-rolling\nnematic states. We calculate the effective constitutive relations that would be\nmeasured through the regime of phase separation into shear bands. We calculate\nphase coexistence by examining the stability of interfacial steady states and\nfind a wide range of possible ``phase'' behaviors."
    },
    {
        "anchor": "The Widom-Rowlinson mixture on a sphere: Elimination of exponential\n  slowing down at first-order phase transitions: Computer simulations of first-order phase transitions using standard toroidal\nboundary conditions are generally hampered by exponential slowing down. This is\npartly due to interface formation, and partly due to shape transitions. The\nlatter occur when droplets become large such that they self-interact through\nthe periodic boundaries. On a spherical simulation topology, however, shape\ntransitions are absent. By using an appropriate bias function, we expect that\nexponential slowing down can be largely eliminated. In this work, these ideas\nare applied to the two-dimensional Widom-Rowlinson mixture confined to the\nsurface of a sphere. Indeed, on the sphere, we find that the number of Monte\nCarlo steps needed to sample a first-order phase transition does not increase\nexponentially with system size, but rather as a power law $\\tau \\propto\nV^\\alpha$, with $\\alpha \\approx 2.5$, and $V$ the system area. This is\nremarkably close to a random walk for which $\\alpha$ equals 2. The benefit of\nthis improved scaling behavior for biased sampling methods, such as the\nWang-Landau algorithm, is investigated in detail.",
        "positive": "Hamiltonian Dynamics and Structural States of Two-Dimensional\n  Microswimmers: We show that a two-dimensional system of flocking microswimmers interacting\nhydrodynamically can be expressed using a Hamiltonian formalism. The\nHamiltonian depends strictly on the angles between the particles and their\nswimming orientation, thereby restricting their available phase-space.\nSimulations of co-oriented microswimmers evolve into \"escalators\" - sharp lines\nat a particular tilt along which particles circulate. The conservation of the\nHamiltonian and its symmetry germinate the self-assembly of the observed\nsteady-state arrangements as confirmed by stability analysis."
    },
    {
        "anchor": "Toward a High Performance IPMC Soft Actuator using A disturbance-aided\n  method: Besides the advantages of Ionic polymer-metal composites (IPMCs) for\nbiomedical applications, there are some drawbacks in their performance, which\ncan be enhanced. One of those critical drawbacks is \"back relaxation\" (BR). If\nwe apply a step voltage to IPMC, it will bend in the anode direction.\nAfterward, there is an unwanted and relatively slow counter-bending toward the\ncathode side. There are some disadvantages in the current BR control methods of\nIPMC actuators that prevent them from being used in real applications. This\npaper presents a new non-feedback method for eliminating the BR effect of\nnon-patterned IPMCs by using a relatively high-frequency disturbance and\nproving it by theoretical and experimental explanations. The results show that\nthe proposed method, needless to have any pattern on the electrodes of the\nIPMCs, can significantly eliminate the BR effect. Unlike the patterned IPMCs,\nno reduction will occur in the bending amplitude of IPMC, and even we can see\nthe increased bending amplitude.",
        "positive": "Formation of molecules and entangled atomic pairs from atomic BEC due to\n  Feshbach resonance: Bose-Einstein condensate (BEC) is considered under conditions of Feshbach\nresonance in two-atom collisions due to a coupling of atomic pair and resonant\nmolecular states. The association of condensate atoms can form a molecular BEC,\nand the molecules can dissociate to pairs of entangled atoms in two-mode\nsqueezed states. Both entanglement and squeezing can be applied to quantum\nmeasurements and information processing.\n  The processes in the atom-molecule quantum gas are analyzed using two\ntheoretical approaches. The mean-field one takes into account deactivating\ncollisions of resonant molecules with other atoms and molecules, neglecting\nquantum fluctuations. This method allows analysis of inhomogeneous systems,\nsuch as expanding BEC. The non-mean-field approach -- the parametric\napproximation -- takes into account both deactivation and quantum fluctuations.\nThis method allows determination of optimal conditions for formation of\nmolecular BEC and describes Bose-enhanced dissociation of molecular BEC, as\nwell as entanglement and squeezing of the non-condensate atoms."
    },
    {
        "anchor": "Automated tracking of colloidal clusters with sub-pixel accuracy and\n  precision: Quantitative tracking of features from video images is a basic technique\nemployed in many areas of science. Here, we present a method for the tracking\nof features that partially overlap, in order to be able to track so-called\ncolloidal molecules. Our approach implements two improvements into existing\nparticle tracking algorithms. Firstly, we use the history of previously\nidentified feature locations to successfully find their positions in\nconsecutive frames. Secondly, we present a framework for non-linear\nleast-squares fitting to summed radial model functions and analyze the accuracy\n(bias) and precision (random error) of the method on artificial data. We find\nthat our tracking algorithm correctly identifies overlapping features with an\naccuracy below 0.2% of the feature radius and a precision of 0.1 to 0.01 pixels\nfor a typical image of a colloidal cluster. Finally, we use our method to\nextract the three-dimensional diffusion tensor from the Brownian motion of\ncolloidal dimers.",
        "positive": "Electron Scattering in Liquid Water and Amorphous Ice: A Striking\n  Resemblance: The lack of accurate low-energy electron scattering cross sections for liquid\nwater is a substantial source of uncertainty in the modelling of radiation\nchemistry and biology. The use of existing amorphous ice scattering cross\nsections for lack of liquid data has been discussed controversially over\ndecades. Here, we compare experimental photoemission data of liquid water with\ncorresponding predictions using amorphous ice cross sections, with the aim of\nresolving the debate regarding the difference of electron scattering in liquid\nwater and amorphous ice. We find very similar scattering properties in the\nliquid and the ice for electron kinetic energies up to a few hundred electron\nvolts. The scattering cross sections recommended here for liquid water are an\nextension of the amorphous ice cross sections. Within the framework of\ncurrently available experimental data, our work answers one of the most debated\nquestions regarding electron scattering in liquid water."
    },
    {
        "anchor": "Colloidal suspensions of C-particles: Entanglement, percolation and\n  microrheology: We explore structural and dynamical behavior of concentrated colloidal\nsuspensions made up by C-shape particles using Brownian dynamics computer\nsimulations and theory. In particular, we focus on the entanglement process\nbetween nearby particles for almost closed C-shapes with a small opening angle.\nDepending on the opening angle and the particle concentration, there is a\npercolation transition for the cluster of entangled particles which shows the\nclassical scaling characteristics. In a broad density range below the\npercolation threshold, we find a stretched exponential function for the\ndynamical decorrelation of the entanglement process. Finally, we study a set-up\ntypical in microrheology by dragging a single tagged particle with constant\nspeed through the suspension. We measure the cluster connected to and dragged\nwith this tagged particle. In agreement with a phenomenological theory, the\nsize of the dragged cluster depends on the dragging direction and increases\nmarkedly with the dragging speed.",
        "positive": "Deformation and sorting of capsules in a T-junction: We study experimentally the motion and deformation of individual capsules\ntransported by a constant volume-flux flow of low Reynolds number, through the\nT-junction of a channel with rectangular cross-section. We use millimetric\novalbumin-alginate capsules which we manufacture and characterise independently\nof the flow experiment. Centred capsules travel at constant velocity down the\nstraight channel leading to the T-junction where they decelerate and expand in\nthe spanwise direction before turning into one of the two identical daughter\nchannels. There, non-inertial lift forces act to re-centre them and relax their\nshape until they reach a steady state of propagation. We find that the dynamics\nof fixed-size capsules within our channel geometry are governed by a capillary\nnumber Ca defined as the ratio of viscous shear forces to elastic restoring\nforces. We quantify the elastic forces by statically compressing the capsule to\n50% of its initial diameter between parallel plates rather than by the Young's\nmodulus of the encapsulating membrane, in order to account for different\nmembrane thickness, pre-inflation and non-linear elastic deformation. We show\nthat the maximum extension in the T-junction of capsules of different stiffness\ncollapses onto a master curve in Ca. Thus, it provides a sensitive measure of\nthe relative stiffness of capsules at constant flow rate, particularly for\nsofter capsules. We also find that the T-junction can sort fixed-size capsules\naccording to their stiffness because the position in the T-junction from which\ncapsules are entrained into the daughter channel depends uniquely on Ca. We\ndemonstrate that a T-junction can be used as a sorting device by enhancing this\ninitial capsule separation through a diffuser."
    },
    {
        "anchor": "Machine Learning of Implicit Combinatorial Rules in Mechanical\n  Metamaterials: Combinatorial problems arising in puzzles, origami, and (meta)material design\nhave rare sets of solutions, which define complex and sharply delineated\nboundaries in configuration space. These boundaries are difficult to capture\nwith conventional statistical and numerical methods. Here we show that\nconvolutional neural networks can learn to recognize these boundaries for\ncombinatorial mechanical metamaterials, down to finest detail, despite using\nheavily undersampled training sets, and can successfully generalize. This\nsuggests that the network infers the underlying combinatorial rules from the\nsparse training set, opening up new possibilities for complex design of\n(meta)materials.",
        "positive": "Unoccupied space and short-range order characterization in polymers\n  under heat treatment: Large scale molecular dynamics simulations on polyvinyl alcohol were used to\ninvestigate the distribution of unoccupied space under different heat\ntreatments. Representative volume elements consisting of 3600 chains of 300\nmonomers were equilibrated at melt state and cooled by different cooling rates.\nThe positions of center of mass of the monomers were extracted and a series of\nspatial analysis were conducted to estimate the distribution of free volume or\nunoccupied space by Voronoi tessellation algorithm. An open-source software was\nemployed which incorporates both compilers of Matlab and C programing languages\nto reduce the computational costs associated with Voronoi calculations and\nstatistical analysis. The results confirmed that low free volume content is\nachievable through annealing while high free volume content is achievable\nthrough quenching samples at high cooling rates. An appreciable degree of\nshort-range order in the packing of chains is revealed in annealed samples."
    },
    {
        "anchor": "Combinatorial Design of Textured Mechanical Metamaterials: The structural complexity of metamaterials is limitless, although in\npractice, most designs comprise periodic architectures which lead to materials\nwith spatially homogeneous features. More advanced tasks, arising in e.g. soft\nrobotics, prosthetics and wearable tech, involve spatially textured mechanical\nfunctionality which require aperiodic architectures. However, a na\\\"ive\nimplementation of such structural complexity invariably leads to frustration,\nwhich prevents coherent operation and impedes functionality. Here we introduce\na combinatorial strategy for the design of aperiodic yet frustration-free\nmechanical metamaterials, whom we show to exhibit spatially textured\nfunctionalities. We implement this strategy using cubic building blocks -\nvoxels - which deform anisotropically, a local stacking rule which allows\ncooperative shape changes by guaranteeing that deformed building blocks fit as\nin a 3D jigsaw puzzle, and 3D printing. We show that, first, these aperiodic\nmetamaterials exhibit long-range holographic order, where the 2D pixelated\nsurface texture dictates the 3D interior voxel arrangement. Second, they act as\nprogrammable shape shifters, morphing into spatially complex but predictable\nand designable shapes when uniaxially compressed. Third, their mechanical\nresponse to compression by a textured surface reveals their ability to perform\nsensing and pattern analysis. Combinatorial design thus opens a new avenue\ntowards mechanical metamaterials with unusual order and machine-like\nfunctionalities.",
        "positive": "Fluctuation-induced phase separation in metric and topological models of\n  collective motion: We study the role of noise on the nature of the transition to collective\nmotion in dry active matter. Starting from field theories that predict a\ncontinuous transition at the deterministic level, we show that fluctuations\ninduce a density-dependent shift of the onset of order, which in turns changes\nthe nature of the transition into a phase-separation scenario. Our results\napply to a range of systems, including the topological models in which\nparticles interact with a fixed number of nearest neighbors, which were\nbelieved so far to exhibit a continuous onset of order. Our analytical\npredictions are confirmed by numerical simulations of fluctuating hydrodynamics\nand microscopic models."
    },
    {
        "anchor": "Stress Relaxation in Aging Soft Colloidal Glasses: We investigate the stress relaxation behavior on the application of step\nstrains to aging aqueous suspensions of the synthetic clay Laponite. The stress\nexhibits a two-step decay, from which the slow relaxation modes are extracted\nas functions of the sample ages and applied step strain deformations.\nInterestingly, the slow time scales that we estimate show a dramatic\nenhancement with increasing strain amplitudes. We argue that the system ends up\nexploring the deeper sections of its energy landscape following the application\nof the step strain.",
        "positive": "Crowding-Regulated Binding of Divalent Biomolecules: Macromolecular crowding affects biophysical processes as diverse as\ndiffusion, gene expression, cell growth, and senescence. Yet, there is no\ncomprehensive understanding of how crowding affects reactions, particularly\nmultivalent binding. Herein, we use scaled particle theory and develop a\nmolecular simulation method to investigate the binding of monovalent to\ndivalent biomolecules. We find that crowding can increase or reduce\ncooperativity--the extent to which the binding of a second molecule is enhanced\nafter binding a first molecule--by orders of magnitude, depending on the sizes\nof the involved molecular complexes. Cooperativity generally increases when a\ndivalent molecule swells and then shrinks upon binding two ligands. Our\ncalculations also reveal that, in some cases, crowding enables binding that\ndoes not occur otherwise. As an immunological example, we consider\nImmunoglobulin G-antigen binding and show that crowding enhances its\ncooperativity in bulk but reduces it when an Immunoglobulin G binds antigens on\na surface."
    },
    {
        "anchor": "Shapes of Non-symmetric Capillary Bridges: Here we study the shapes of droplets captured between chemically distinct\nparallel plates. This work is a preliminary step toward characterizing the\ninfluence of second-phase bridging between biomolecular surfaces on their\nsolution contacts, i.e., capillary attraction or repulsion. We obtain a simple,\nvariable-separated quadrature formula for the bridge shape. The technical\ncomplication of double-ended boundary conditions on the shapes of non-symmetric\nbridges is addressed by studying waists in the bridge shape, i.e., points where\nthe bridge silhouette has zero derivative. Waists are always expected with\nsymmetric bridges, but waist-points can serve to characterize shape segments in\ngeneral cases. We study how waist possibilities depend on the physical input to\nthese problems, noting that these formulae change with the sign of the\ninside-outside pressure difference of the bridge. These results permit a\nvariety of different interesting shapes, and the development below is\naccompanied by several examples.",
        "positive": "Oscillatory decay of a two-component Bose-Einstein condensate: We study the decay of a two-component Bose-Einstein condensate with negative\neffective interaction energy. With a decreasing atom number due to losses, the\natom-atom interaction becomes less important and the system undergoes a\ntransition from a bistable Josephson regime to the monostable Rabi regime,\ndisplaying oscillations in phase and number. We study the equations of motion\nand derive an analytical expression for the oscillation amplitude. A quantum\ntrajectory simulation reveals that the classical description fails for low\nemission rates, as expected from analytical considerations. Observation of the\nproposed effect will provide evidence for negative effective interaction."
    },
    {
        "anchor": "Buckled nano rod - a two state system and its dynamics using system plus\n  reservoir model: We consider a suspended elastic rod under longitudinal compression. The\ncompression can be used to adjust potential energy for transverse displacements\nfrom harmonic to double well regime. As compressional strain is increased to\nthe buckling instability, the frequency of fundamental vibrational mode drops\ncontinuously to zero (first buckling instability). As one tunes the separation\nbetween ends of a rod, the system remains stable beyond the instability and\ndevelops a double well potential for transverse motion. The two minima in\npotential energy curve describe two possible buckled states at a particular\nstrain. From one buckled state it can go over to the other by thermal\nfluctuations or quantum tunnelling. Using a continuum approach and transition\nstate theory (TST) one can calculate the rate of conversion from one state to\nother. Saddle point for the change from one state to other is the straight rod\nconfiguration. The rate, however, diverges at the second buckling instability.\nAt this point, the straight rod configuration, which was a saddle till then,\nbecomes hill top and two new saddles are generated. The new saddles have bent\nconfigurations and as rod goes through further instabilities, they remain\nstable and the rate calculated according to harmonic approximation around\nsaddle point remains finite. In our earlier paper classical rate calculation\nincluding friction has been carried out [J. Comput. Theor. Nanosci. {\\bf 4}\n(2007) {\\it 1}], by assuming that each segment of the rod is coupled to its own\ncollection of harmonic oscillators - our rate expression is well behaved\nthrough the second buckling instability. In this paper we have extended our\nmethod to calculate quantum rate using the same system plus reservoir model. We\nfind that friction lowers the rate of conversion.",
        "positive": "Momentum state engineering and control in Bose-Einstein condensates: We demonstrate theoretically the use of genetic learning algorithms to\ncoherently control the dynamics of a Bose-Einstein condensate. We consider\nspecifically the situation of a condensate in an optical lattice formed by two\ncounterpropagating laser beams. The frequency detuning between the lasers acts\nas a control parameter that can be used to precisely manipulate the condensate\neven in the presence of a significant mean-field energy. We illustrate this\nprocedure in the coherent acceleration of a condensate and in the preparation\nof a superposition of prescribed relative phase."
    },
    {
        "anchor": "Tuning the shear-thickening of suspensions through surface roughness and\n  physico-chemical interactions: Shear thickening denotes the reversible increase in viscosity of a suspension\nof rigid particles under external shear. This ubiquitous phenomenon has been\ndocumented in a broad variety of multiphase particulate systems, while its\nmicroscopic origin has been successively attributed to hydrodynamic\ninteractions and frictional contact between particles. The relative\ncontribution of these two phenomena to the magnitude of shear thickening is\nstill highly debated and we report here a discriminating experimental study\nusing a model shear-thickening suspension that allows us to tune independently\nboth the surface chemistry and the surface roughness of the particles. We show\nhere that both properties matter when it comes to continuous shear thickening\n(CST) and that the presence of hydrogen bonds between the particles is\nessential to achieve discontinuous shear thickening (DST) by enhancing solid\nfriction between closely contacting particles. Moreover, a simple argument\nallows us to predict the onset of CST, which for these very rough particles\noccurs at a critical volume fraction much lower than that previously reported\nin the literature. Finally, we demonstrate how mixtures of particles with\nopposing surface chemistry make it possible to finely tune the shear-thickening\nresponse of the suspension at a fixed volume fraction, paving the way for a\nfine control of the shear-thickening transition in engineering applications.",
        "positive": "Criticality and phase separation in a two-dimensional binary colloidal\n  fluid induced by the solvent critical behavior: We present an experimental and theoretical study of the phase behavior of a\nbinary mixture of colloids with opposite adsorption preferences in a critical\nsolvent. As a result of the attractive and repulsive critical Casimir forces,\nthe critical fluctuations of the solvent lead to a further critical point in\nthe colloidal system, i.e. to a critical colloidal-liquid--colloidal-liquid\ndemixing phase transition which is controlled by the solvent temperature. Our\nexperimental findings are in good agreement with calculations based on a simple\napproximation for the free energy of the system."
    },
    {
        "anchor": "Dense packings of spheres in cylinders I. Simulations: We study the optimal packing of hard spheres in an infinitely long cylinder,\nusing simulated annealing, and compare our results with the analogous problem\nof packing disks on the unrolled surface of a cylinder. The densest structures\nare described and tabulated in detail up to D/d=2.873 (ratio of cylinder and\nsphere diameters). This extends previous computations into the range of\nstructures which include internal spheres that are not in contact with the\ncylinder.",
        "positive": "Arrested Cracks in Nonlinear Lattice Models of Brittle Fracture: We generalize lattice models of brittle fracture to arbitrary nonlinear force\nlaws and study the existence of arrested semi-infinite cracks. Unlike what is\nseen in the discontinuous case studied to date, the range in driving\ndisplacement for which these arrested cracks exist is very small. Also, our\nresults indicate that small changes in the vicinity of the crack tip can have\nan extremely large effect on arrested cracks. Finally, we briefly discuss the\npossible relevance of our findings to recent experiments."
    },
    {
        "anchor": "Point force manipulation and activated dynamics of polymers adsorbed on\n  structured substrates: We study the activated motion of adsorbed polymers which are driven over a\nstructured substrate by a localized point force.Our theory applies to\nexperiments with single polymers using, for example, tips of scanning force\nmicroscopes to drag the polymer.We consider both flexible and semiflexible\npolymers,and the lateral surface structure is represented by double-well or\nperiodic potentials. The dynamics is governed by kink-like excitations for\nwhich we calculate shapes, energies, and critical point forces. Thermally\nactivated motion proceeds by the nucleation of a kink-antikink pair at the\npoint where the force is applied and subsequent diffusive separation of kink\nand antikink. In the stationary state of the driven polymer, the collective\nkink dynamics can be described by an one-dimensional symmetric simple exclusion\nprocess.",
        "positive": "Plastic ridge formation in a compressed thin amorphous film: We demonstrate that surface morphogenesis in compressed thin films may result\nfrom spatially correlated plastic activity. A soft glassy film strongly\nadhering to a smooth and rigid substrate and subjected to uniaxial compression,\nindeed, does not undergo any global elastic pattern-forming instability, but\nresponds plastically via localized burst events that self-organize, leading to\nthe emergence of a series of parallel ridges transverse to the compression\naxis. This phenomenon has been completely overlooked, but results from common\nfeatures of the plastic response of glasses, hence should be highly generic for\ncompressed glassy thin films."
    },
    {
        "anchor": "Electrostatics on the sphere with applications to Monte Carlo\n  simulations of two dimensional polar fluids: We present two methods for solving the electrostatics of point charges and\nmultipoles on the surface of a sphere, \\textit{i.e.} in the space\n$\\mathcal{S}_{2}$, with applications to numerical simulations of\ntwo-dimensional polar fluids.\n  In the first approach, point charges are associated with uniform neutralizing\nbackgrounds to form neutral pseudo-charges, while, in the second, one instead\nconsiders bi-charges, \\textit{i.e.} dumbells of antipodal point charges of\nopposite signs. We establish the expressions of the electric potentials of\npseudo- and bi-charges as isotropic solutions of the Laplace-Beltrami equation\nin $\\mathcal{S}_{2}$. A multipolar expansion of pseudo- and bi-charge\npotentials leads to the electric potentials of mono- and bi-multipoles\nrespectively. These potentials constitute non-isotropic solutions of the\nLaplace-Beltrami equation the general solution of which in spherical\ncoordinates is recast under a new appealing form.\n  We then focus on the case of mono- and bi-dipoles and build the theory of\ndielectric media in $\\mathcal{S}_{2}$. We notably obtain the expression of the\nstatic dielectric constant of a uniform isotropic polar fluid living in\n$\\mathcal{S}_{2}$ in term of the polarization fluctuations of subdomains of\n$\\mathcal{S}_{2}$. We also derive the long range behavior of the equilibrium\npair correlation function under the assumption that it is governed by\nmacroscopic electrostatics. These theoretical developments find their\napplication in Monte Carlo simulations of the $2D$ fluid of dipolar hard\nspheres.\n  Some preliminary numerical experiments are discussed with a special emphasis\non finite size effects, a careful study of the thermodynamic limit, and a check\nof the theoretical predictions for the asymptotic behavior of the pair\ncorrelation function.",
        "positive": "Kepler orbits of settling discs: The collective dynamics of objects moving through a viscous fluid is complex\nand counterintuitive. A key to understanding the role of nontrivial particle\nshape in this complexity is the interaction of a pair of sedimenting spheroids.\nWe report experimental results on two discs settling at negligible Reynolds\nnumber ($\\simeq 10^{-4}$), finding two classes of bound periodic orbits, each\nwith transitions to scattering states. We account for these dynamics, at\nleading far-field order, through an effective Hamiltonian in which\ngravitational driving endows orientation with the properties of momentum. This\nleads to a precise correspondence with the Kepler problem of planetary motion\nfor a wide range of initial conditions, and also to orbits with no Keplerian\nanalogue. This notion of internal degrees of freedom manifesting themselves as\nan effective inertia is potentially a more general tool in Stokesian driven\nsystems."
    },
    {
        "anchor": "Nonadiabatic effects in the dynamics of atoms confined in a cylindric\n  time-orbiting-potential magnetic trap: In a time-orbiting-potential magnetic trap the neutral atoms are confined by\nmeans of an inhomogeneous magnetic field superimposed to an uniform rotating\none. We perform an analytic study of the atomic motion by taking into account\nthe nonadiabatic effects arising from the spin dynamics about the local\nmagnetic field. Geometric-like magnetic-fields determined by the Berry's phase\nappear within the quantum description. The application of a variational\nprocedure on the original quantum equation leads to a set of dynamical\nevolution equations for the quantum average value of the position operator and\nof the spin variables. Within this approximation we derive the\nquantum-mechanical ground state configuration matching the classical adiabatic\nsolution and perform some numerical simulations.",
        "positive": "Singular electrostatic energy of nanoparticle clusters: The binding of clusters of metal nanoparticles is partly electrostatic. We\naddress difficulties in calculating the electrostatic energy when high charging\nenergies limit the total charge to a single quantum, entailing unequal\npotentials on the particles. We show that the energy at small separation $h$\nhas a singular logarithmic dependence on $h$. We derive a general form for this\nenergy in terms of the singular capacitance of two spheres in near contact\n$c(h)$, together with nonsingular geometric features of the cluster. Using this\nform, we determine the energies of various clusters, finding that more compact\nclusters are more stable. These energies are proposed to be significant for\nmetal-semiconductor binary nanoparticle lattices found experimentally. We\nsketch how these effects should dictate the relative abundances of metal\nnanoparticle clusters in nonpolar solvents."
    },
    {
        "anchor": "Self-assembly and crystallisation of indented colloids at a planar wall: We report experimental and simulation studies of the structure of a monolayer\nof indented (\"lock and key\") colloids, on a planar surface. On adding a\nnon-absorbing polymer with prescribed radius and volume fraction, depletion\ninteractions are induced between the colloids, with controlled range and\nstrength. For spherical particles, this leads to crystallisation, but the\nindented colloids crystallise less easily than spheres, in both simulation and\nexperiment. Nevertheless, simulations show that indented colloids do form\nplastic (rotator) crystals. We discuss the conditions under which this occurs,\nand the possibilities of lower-symmetry crystal states. We also comment on the\nkinetic accessibility of these states.",
        "positive": "Collapse of a Bose-Einstein condensate induced by fluctuations of the\n  laser intensity: The dynamics of a metastable attractive Bose-Einstein condensate trapped by a\nsystem of laser beams is analyzed in the presence of small fluctuations of the\nlaser intensity. It is shown that the condensate will eventually collapse. The\nexpected collapse time is inversely proportional to the integrated covariance\nof the time autocorrelation function of the laser intensity and it decays\nlogarithmically with the number of atoms. Numerical simulations of the\nstochastic 3D Gross-Pitaevskii equation confirms analytical predictions for\nsmall and moderate values of mean field interaction."
    },
    {
        "anchor": "Condensation of Self-assembled Lyotropic Chromonic Liquid Crystal Sunset\n  Yellow in Aqueous Solutions Crowded with Polyethylene glycol and Doped with\n  Salt: We use optical and fluorescence microscopy, densitometry, cryo-transmission\nelectron microscopy (cryo-TEM), spectroscopy, and synchrotron X-ray scattering,\nto study the phase behavior of the reversible self-assembled chromonic\naggregates of an anionic dye Sunset Yellow (SSY) in aqueous solutions crowded\nwith an electrically neutral polymer polyethylene glycol (PEG) and doped with\nthe salt NaCl. PEG causes the isotropic SSY solutions to condense into a\nliquid-crystalline region with a high concentration of SSY aggregates,\ncoexisting with a PEG-rich isotropic (I) region. PEG added to the homogeneous\nnematic (N) phase causes separation into the coexisting N and I domains; the\nSSY concentration in the N domains is higher than the original concentration of\nPEG-free N phase. Finally, addition of PEG to the highly concentrated\nhomogeneous N phase causes separation into the coexisting columnar hexagonal\n(C) phase and I phase. This behavior can be qualitatively explained by the\ndepletion (excluded volume) effects that act at two different levels: at the\nlevel of aggregate assembly from monomers and short aggregates and at the level\nof inter-aggregate packing. We also show a strong effect of a monovalent salt\nNaCl on phase diagrams that is different for high and low concentrations of\nSSY. Upon the addition of salt, dilute I solutions of SSY show appearance of\nthe condensed N domains, but the highly concentrated C phase transforms into a\ncoexisting I and N domains. We suggest that the salt-induced screening of\nelectric charges at the surface of chromonic aggregates leads to two different\neffects: (a) increase of the scission energy and the contour length of\naggregates, and (b) decrease of the persistence length of SSY aggregates.",
        "positive": "The emergence of soft-glassy mechanics in simulated foams: Several seemingly different soft materials, including foams, cells, and many\ncomplex fluids, exhibit remarkably similar rheological properties and\nmicroscopic dynamics, termed soft glassy mechanics. Here, we show that such\nbehavior emerges from a simple model of a damped ripening foam, for\nsufficiently weak damping. In particular, we observe intermittent avalanchey\ndynamics, bubble super-diffusion, and power-law rheology that vary as the\ndamping factor is changed. In the limit of weak damping, the dynamics are\ndetermined by the tortuous low-lying portions of the energy landscape, as\ndescribed in a recent study. For strong damping the viscous stresses cause the\nsystem configuration to evolve along higher energy paths, washing out\nsmall-scale tortuosity and producing motion with an increasingly ballistic\ncharacter. Using a microrheological approach, the linear viscoelastic response\nof the model can be efficiently calculated. This resembles the power-law\nrheology expected for soft glassy mechanics, but unexpectedly, is only weakly\nsensitive to the damping parameter. Lastly, we study the reported memory effect\nin foams after large perturbations and find that the timescale of the memory\ngoes to zero as the damping parameter vanishes, suggesting that the effect is\ndue to viscous stress relaxation rather than slow structural changes stabilized\nby the energy landscape."
    },
    {
        "anchor": "To be or not to be polar: the ferroelectric and antiferroelectric\n  nematic phases: We report the properties of two new series of compounds that show the\nferroelectric nematic phase in which the length of a terminal chain is varied.\nThe longer the terminal chain, the weaker the dipole-dipole interactions of the\nmolecules are along the director, and thus the lower the temperature at which\nthe axially ferroelectric nematic phase is formed. For homologues of\nintermediate chain length, between the non-polar and ferroelectric nematic\nphases, there is a wide temperature range nematic phase with antiferroelectric\ncharacter. The size of the antiparallel ferroelectric domains critically\nincreases upon transition to the ferroelectric phase. In dielectric studies,\nboth collective (\"ferroelectric\" and non-collective fluctuations are present,\nthe \"ferroelectric\" mode softens weakly at the N-NX phase transition because\nthe polar order in this phase is weak. The transition to the NF phase is\ncharacterized by a much stronger lowering of the mode relaxation frequency and\nan increase in its strength, typical critical behavior is observed.",
        "positive": "Exceptionally Dense and Resilient Polydisperse Disk Packings: Understanding the way disordered particle packings transition between jammed\n(rigid) and unjammed (fluid) states is of both great practical importance and\nstrong fundamental interest. The values of critical packing fraction (and other\nstate variables) at the jamming transition are protocol dependent. Here, we\ndemonstrate that this variability can be systematically traced to structural\nmeasures of packing, as well as to energy measures inside the jamming regime. A\nnovel generalized simultaneous particle swap algorithm constructs overjammed\nstates of desired energy, which upon decompression lead to predictable critical\npacking fractions. Thus, for a given set of particle sizes, states with\nextraordinarily high critical packing fractions can be found efficiently, which\nsustain substantial shear strain and preserve their special structure over the\nentire jammed domain. The close relation revealed here between the energy\nlandscape of overjammed soft-particle packings and the behavior near the\njamming transition points towards new ways of understanding and constructing\ndisordered materials with exceptional properties."
    },
    {
        "anchor": "Precision measurement of tribocharging in acoustically levitated\n  sub-millimeter grains: Contact electrification of dielectric grains forms the basis for a myriad of\nphysical phenomena. However, even the basic aspects of collisional charging\nbetween grains are still unclear. Here we develop a new experimental method,\nbased on acoustic levitation, which allows us to controllably and repeatedly\ncollide two sub-millimeter grains and measure the evolution of their electric\ncharges. This is therefore the first tribocharging experiment to provide\ncomplete electric isolation for the grain-grain system from its surroundings.\nWe use this method to measure collisional charging rates between pairs of\ngrains for three different material combinations: polyethylene-polyethylene,\npolystyrene-polystyrene, and polystyrene-sulfonated polystyrene. The ability to\ndirectly and noninvasively collide particles of different constituent\nmaterials, chemical functionality, size, and shape opens the door to detailed\nstudies of collisional charging in granular materials.",
        "positive": "Eukaryotic swimming cells are shaped by hydrodynamic constraints: Eukaryotic swimming cells such as spermatozoa, algae or protozoa use flagella\nor cilia to move in viscous fluids. The motion of their flexible appendages in\nthe surrounding fluid induces propulsive forces that balance with the viscous\ndrag on the cells and lead to a directed swimming motion. Here, we use our\nrecently built database of cell motility (BOSO-Micro) to investigate the extent\nto which the shapes of eukaryotic swimming cells may be optimal from a\nhydrodynamic standpoint. We first examine the morphology of flexible flagella\nundergoing waving deformation and show that their amplitude-to-wavelength ratio\nis near the one predicted theoretically to optimise the propulsive efficiency\nof active filaments. Next, we consider ciliates, for which locomotion is\ninduced by the collective beating of short cilia covering their surface. We\nshow that the aspect ratio of ciliates are close to the one predicted to\nminimise the viscous drag of the cell body. Both results strongly suggest a key\nrole played by hydrodynamic constraints, in particular viscous drag, in shaping\neukaryotic swimming cells."
    },
    {
        "anchor": "Classical dynamical density functional theory: from fundamentals to\n  applications: Classical dynamical density functional theory (DDFT) is one of the\ncornerstones of modern statistical mechanics. It is an extension of the highly\nsuccessful method of classical density functional theory (DFT) to\nnonequilibrium systems. Originally developed for the treatment of simple and\ncomplex fluids, DDFT is now applied in fields as diverse as hydrodynamics,\nmaterials science, chemistry, biology, and plasma physics. In this review, we\ngive a broad overview over classical DDFT. We explain its theoretical\nfoundations and the ways in which it can be derived. The relations between the\ndifferent forms of deterministic and stochastic DDFT as well as between DDFT\nand related theories, such as quantum-mechanical time-dependent DFT, mode\ncoupling theory, and phase field crystal models, are clarified. Moreover, we\ndiscuss the wide spectrum of extensions of DDFT, which covers methods with\nadditional order parameters (like extended DDFT), exact approaches (like power\nfunctional theory), and systems with more complex dynamics (like active\nmatter). Finally, the large variety of applications, ranging from fluid\nmechanics and polymer physics to solidification, pattern formation, biophysics,\nand electrochemistry, is presented.",
        "positive": "Curvature dependence of the interfacial heat and mass transfer\n  coefficients: Nucleation is often accompanied by heat transfer between the surroundings and\na nucleus of a new phase. The interface between two phases gives an additional\nresistance to this transfer. For small nuclei the interfacial curvature is\nhigh, which affects not only equilibrium quantities such as surface tension,\nbut also the transport properties. In particular, high curvature affects the\ninterfacial resistance to heat and mass transfer. We develop a framework for\ndetermining the curvature dependence of the interfacial heat and mass transfer\nresistances. We determine the interfacial resistances as a function of a\ncurvature. The analysis is performed for a bubble of a one-component fluid and\nmay be extended to various nuclei of multicomponent systems. The curvature\ndependence of the interfacial resistances is important in modeling transport\nprocesses in multiphase systems."
    },
    {
        "anchor": "Where the linearized Poisson-Boltzmann cell model fails: (I) spurious\n  phase separation in charged colloidal suspensions: We perform a linearization of the Poisson-Boltzmann (PB) density functional\nfor spherical Wigner-Seitz cells that yields Debye-H\\\"uckel-like equations\nagreeing asymptotically with the PB results in the weak-coupling\n(high-temperature) limit. Both the canonical (fixed number of microions) as\nwell as the semi-grand-canonical (in contact with an infinite salt reservoir)\ncases are considered and discussed in a unified linearized framework. In the\ncanonical case, for sufficiently large colloidal charges the linearized theory\npredicts the occurrence of a thermodynamical instability with an associated\nphase separation of the homogeneous suspension into dilute (gas) and dense\n(liquid) phases. In the semi-grand-canonical case it is predicted that the\nisothermal compressibility and the osmotic-pressure difference between the\ncolloidal suspension and the salt reservoir become negative in the\nlow-temperature, high-surface charge or infinite-dilution (of polyions) limits.\nAs already pointed out in the literature for the latter case, these features\nare in disagreement with the exact nonlinear PB solution inside a Wigner-Seitz\ncell and are thus artifacts of the linearization. By using explicitly\ngauge-invariant forms of the electrostatic potential we show that these\nartifacts, although thermodynamically consistent with quadratic expansions of\nthe nonlinear functional and osmotic pressure, may be traced back to the\nnon-fulfillment of the underlying assumptions of the linearization.",
        "positive": "Deep learning approaches to surrogates for solving the diffusion\n  equation for mechanistic real-world simulations: In many mechanistic medical, biological, physical and engineered\nspatiotemporal dynamic models the numerical solution of partial differential\nequations (PDEs) can make simulations impractically slow. Biological models\nrequire the simultaneous calculation of the spatial variation of concentration\nof dozens of diffusing chemical species. Machine learning surrogates, neural\nnetworks trained to provide approximate solutions to such complicated numerical\nproblems, can often provide speed-ups of several orders of magnitude compared\nto direct calculation. PDE surrogates enable use of larger models than are\npossible with direct calculation and can make including such simulations in\nreal-time or near-real time workflows practical. Creating a surrogate requires\nrunning the direct calculation tens of thousands of times to generate training\ndata and then training the neural network, both of which are computationally\nexpensive. We use a Convolutional Neural Network to approximate the stationary\nsolution to the diffusion equation in the case of two equal-diameter, circular,\nconstant-value sources located at random positions in a two-dimensional square\ndomain with absorbing boundary conditions. To improve convergence during\ntraining, we apply a training approach that uses roll-back to reject stochastic\nchanges to the network that increase the loss function. The trained neural\nnetwork approximation is about 1e3 times faster than the direct calculation for\nindividual replicas. Because different applications will have different\ncriteria for acceptable approximation accuracy, we discuss a variety of loss\nfunctions and accuracy estimators that can help select the best network for a\nparticular application."
    },
    {
        "anchor": "Membrane Viscosity Determined from Shear-Driven Flow in Giant Vesicles: The viscosity of lipid bilayer membranes plays an important role in\ndetermining the diffusion constant of embedded proteins and the dynamics of\nmembrane deformations, yet it has historically proven very difficult to\nmeasure. Here we introduce a new method based on quantification of the\nlarge-scale circulation patterns induced inside vesicles adhered to a solid\nsurface and subjected to simple shear flow in a microfluidic device. Particle\nImage Velocimetry based on spinning disk confocal imaging of tracer particles\ninside and outside of the vesicle, and tracking of phase-separated membrane\ndomains are used to reconstruct the full three-dimensional flow pattern induced\nby the shear. These measurements show excellent agreement with the predictions\nof a recent theoretical analysis, and allow direct determination of the\nmembrane viscosity.",
        "positive": "Chaotic Dynamics in Shear-thickening Surfactant Solutions: We report the observation of dynamical behaviour in dilute, aqueous solutions\nof a surfactant CTAT (cetyl trimethylammonium p-toluenesulphonate), below the\noverlap concentration c$^{\\star}$. At these concentrations, CTAT forms\ncylindrical micelles and shows a pronounced shear thickening transition above a\nconcentration-dependent critical shear rate $\\dot\\gamma_{c}$. An analysis of\nthe time-series of the stress relaxations at controlled shear rates in the\nshear-thickening regime shows the existence of correlation dimensions greater\nthan two and positive Lyapunov exponents. This indicates the existence of\ndeterministic chaos in the dynamics of stress relaxation at these\nconcentrations and shear rates. The observed chaotic behaviour may be\nattributed to the stick-slip between the shear - induced structure (SIS) formed\nin the sheared surfactant solution and the coexisting dilute phase. At still\nhigher shear rates, when the SIS spans the Couette, there is a transition to\nhigher-dimensional dynamics arising out of the breakage and recombination of\nthe SIS."
    },
    {
        "anchor": "A comparative study of crumpling and folding of thin sheets: Crumpling and folding of paper are at rst sight very di erent ways of con\nning thin sheets in a small volume: the former one is random and stochastic\nwhereas the latest one is regular and deterministic. Nevertheless, certain\nsimilarities exist. Crumpling is surprisingly ine cient: a typical crumpled\npaper ball in a waste-bin consists of as much as 80% air. Similarly, if one\nfolds a sheet of paper repeatedly in two, the necessary force becomes so large\nthat it is impossible to fold it more than 6 or 7 times. Here we show that the\nsti ness that builds up in the two processes is of the same nature, and\ntherefore simple folding models allow to capture also the main features of\ncrumpling. An original geometrical approach shows that crumpling is\nhierarchical, just as the repeated folding. For both processes the number of\nlayers increases with the degree of compaction. We nd that for both processes\nthe crumpling force increases as a power law with the number of folded layers,\nand that the dimensionality of the compaction process (crumpling or folding)\ncontrols the exponent of the scaling law between the force and the compaction\nratio.",
        "positive": "Novel Core-Shell Structures for Colloids made from Surfactants and\n  Polymers: We report on the formation of colloidal complexes resulting from the\nelectrostatic self-assembly of polyelectrolyte-neutral block copolymers and\noppositely charged surfactants. The copolymers investigated are asymmetric and\ncharacterized by a large neutral block. Using light, neutron and x-ray\nscattering experiments, we have shown that the colloidal complexes exhibit a\ncore-shell microstructure. The core is described as a dense and disordered\nmicro-phase of micelles connected by the polyelectrolyte blocks, whereas the\nshell is a diffuse brush made from the neutral chains. Colloidal complexes with\ncore-shell structures resemble the well-known amphiphilic block copolymer\nmicelles. The self-assembly mechanism is however different here. It is based on\nthe complexation between opposite charges. This mechanism has recently\nattracted much interest because it allows to associate components of different\nnature, such as organic and inorganic or synthetic and biological."
    },
    {
        "anchor": "Viscosity and Stokes-Einstein relation in deeply supercooled water under\n  pressure: We report measurements of the shear viscosity $\\eta$ in water up to\n$150\\,\\mathrm{MPa}$ and down to $229.5\\,\\mathrm{K}$. This corresponds to more\nthan $30\\,\\mathrm{K}$ supercooling below the melting line. The temperature\ndependence is non-Arrhenius at all pressures, but its functional form at\n$0.1\\,\\mathrm{MPa}$ is qualitatively different from that at all pressures above\n$20\\,\\mathrm{MPa}$. The pressure dependence is non-monotonic, with a\npressure-induced decrease of viscosity by more than 50 % at low temperature.\nCombining our data with literature data on the self-diffusion coefficient\n$D_\\mathrm{s}$ of water, we check the Stokes-Einstein relation which, based on\nhydrodynamics, predicts constancy of $D_\\mathrm{s} \\eta/T$, where $T$ is the\ntemperature. The observed temperature and pressure dependence of $D_\\mathrm{s}\n\\eta/T$ is analogous to that obtained in simulations of a realistic water\nmodel. This analogy suggests that our data are compatible with the existence of\na liquid-liquid critical point at positive pressure in water.",
        "positive": "Structural and Topological Nature of Plasticity in Sheared Granular\n  Materials: Upon mechanical loading, granular materials yield and undergo plastic\ndeformation. The nature of plastic deformation is essential for the development\nof the macroscopic constitutive models and the understanding of shear band\nformation. However, we still do not fully understand the microscopic nature of\nplastic deformation in disordered granular materials. Here we used synchrotron\nX-ray tomography technique to track the structural evolutions of\nthree-dimensional granular materials under shear. We establish that highly\ndistorted coplanar tetrahedra are the structural defects responsible for\nmicroscopic plasticity in disordered granular packings. The elementary plastic\nevents occur through flip events which correspond to a neighbor switching\nprocess among these coplanar tetrahedra (or equivalently as the rotation motion\nof 4-ring disclinations). These events are discrete in space and possess\nspecific orientations with the principal stress direction."
    },
    {
        "anchor": "Shrinking stacking fault through glide of the Shockley partial\n  dislocation in hard-sphere crystal under gravity: Disappearance of a stacking fault in the hard-sphere crystal under gravity,\nsuch as reported by Zhu et al. [Nature 387 (1997) 883], has successfully been\ndemonstrated by Monte Carlo simulations. We previously found that a less\nordered (or defective) crystal formed above a bottom ordered crystal under\nstepwise controlled gravity [Mori et al. J. Chem. Phys. 124 (2006) 174507]. A\ndefect in the upper defective region has been identified with a stacking fault\nfor the (001) growth. We have looked at the shrinking of a stacking fault\nmediated by the motion of the Shockley partial dislocation; the Shockley\npartial dislocation terminating the lower end of the stacking fault glides. In\naddition, the presence of crystal strain, which cooperates with gravity to\nreduce stacking faults, has been observed.",
        "positive": "Connecting shear localization with the long-range correlated polarized\n  stress fields in granular materials: One long-lasting puzzle in amorphous solids is shear localization, where\nlocal plastic deformation involves cooperative particle rearrangements in small\nregions of a few inter-particle distances, self-organizing into shear bands and\neventually leading to the material failure. Understanding the connection\nbetween the structure and dynamics of amorphous solids is essential in physics,\nmaterial sciences, geotechnical and civil engineering, and geophysics. Here we\nshow a deep connection between shear localization and the intrinsic structures\nof internal stresses in an isotropically jammed granular material subject to\nshear. Specifically, we find strong (anti)correlations between the micro shear\nbands and two polarized stress fields along two directions of maximal shear. By\nexploring the tensorial characteristics and the rotational symmetry of force\nnetwork, we reveal that such profound connection is a result of symmetry\nbreaking by shear. Finally, we provide the solid experimental evidence of\nlong-range correlated inherent shear stress in an isotropically jammed granular\nsystem."
    },
    {
        "anchor": "Solid superheating observed in two-dimensional strongly-coupled dusty\n  plasma: It is demonstrated experimentally that strongly-coupled plasma exhibits solid\nsuperheating. A 2D suspension of microspheres in dusty plasma, initially\nself-organized in a solid lattice, was heated and then cooled rapidly by\nturning laser heating on and off. Particles were tracked using video\nmicroscopy, allowing atomistic-scale observation during melting and\nsolidification. During rapid heating, the suspension remained in a solid\nstructure at temperatures above the melting point, demonstrating solid\nsuperheating. Hysteresis diagrams did not indicate liquid supercooling in this\n2D system.",
        "positive": "The ferroelectric nematic phase: An optimum liquid crystal candidate for\n  nonlinear optics: Materials that exhibit high nonlinear optical (NLO) susceptibilities are\nconsidered as promising candidates for a wide range of photonic and electronic\napplications. Here we argue that the ferroelectric nematic (NF) materials have\nsufficient potentialities to become materials for the next-generation of NLO\ndevices. We have carried out a study of the efficiency of optical\nsecond-harmonic generation in a prototype NF material, finding a nonlinear\nsusceptibility of 5.6 pmV-1 in the transparent regime, one of the highest ever\nreported in ferroelectric liquid crystals. Given the fact that the studied\nmolecule was not specifically designed for NLO applications we conclude there\nis still margin to obtain NF materials with enhanced properties that should\nallow their practical use."
    },
    {
        "anchor": "On the density scaling of liquid dynamics: Superpositioning of relaxation data as a function of the product variable\nTV^{\\gamma}, where T is temperature, V the specific volume, and {\\gamma} a\nmaterial constant, is an experimental fact demonstrated for approximately 100\nliquids and polymers. Such scaling behavior would result from the\nintermolecular potential having the form of an inverse power law (IPL),\nsuggesting that an IPL is a good approximation for certain relaxation\nproperties over the relevant range of intermolecular distances. However, the\nderivation of the scaling property of an IPL liquid is based on reduced\nquantities, for example, the reduced relaxation time equal to T^1/2V^-1/3 times\nthe actual relaxation time. The difference between scaling using reduced rather\nthan unreduced units is negligible in the supercooled regime; however, at\nhigher temperature the difference can be substantial, accounting for the\npurported breakdown of the scaling and giving rise to different values of the\nscaling exponent. Only the {\\gamma} obtained using reduced quantities can be\nsensibly related to the intermolecular potential.",
        "positive": "Dynamics in inhomogeneous liquids and glasses via the test particle\n  limit: We show that one may view the self and the distinct part of the van Hove\ndynamic correlation function of a simple fluid as the one-body density\ndistributions of a binary mixture that evolve in time according to dynamical\ndensity functional theory. For a test case of soft core Brownian particles the\ntheory yields results for the van Hove function that agree quantitatively with\nthose of our Brownian dynamics computer simulations. At sufficiently high\ndensities the free energy landscape underlying the dynamics exhibits a barrier\nas a function of the mean particle displacement, shedding new light on the\nnature of glass formation. For hard spheres confined between parallel planar\nwalls the barrier height oscillates in-phase with the local density, implying\nthat the mobility is maximal between layers, which should be experimentally\nobservable in confined colloidal dispersions."
    },
    {
        "anchor": "Cyclization of a Polymer: A First Passage Problem for a Non-Markovian\n  Process: We discuss a problem of cyclization of a polymer molecule, which is an\nimportant example of reaction in a system showing strongly non-Markovian\nbehavior on the timescales of interest. We show that the knowledge of the joint\nthree-time probability distribution of the end-to-end distance is sufficient\nfor the full description of the cyclization kinetics, so that the survival\nprobability follows rigorously as a solution of the Volterra integral equation.\nThe corresponding kinetics can easily be evaluated numerically. We moreover\ndiscuss how do some well-known approximations appear from this exact scheme due\nto decoupling.",
        "positive": "Water's Hydrogen Bond Strength: Water is necessary both for the evolution of life and its continuance. It\npossesses particular properties that cannot be found in other materials and\nthat are required for life-giving processes. These properties are brought about\nby the hydrogen bonded environment particularly evident in liquid water. Each\nliquid water molecule is involved in about four hydrogen bonds with strengths\nconsiderably less than covalent bonds but considerably greater than the natural\nthermal energy. These hydrogen bonds are roughly tetrahedrally arranged such\nthat when strongly formed the local clustering expands, decreasing the density.\nSuch low density structuring naturally occurs at low and supercooled\ntemperatures and gives rise to many physical and chemical properties that\nevidence the particular uniqueness of liquid water. If aqueous hydrogen bonds\nwere actually somewhat stronger then water would behave similar to a glass,\nwhereas if they were weaker then water would be a gas and only exist as a\nliquid at sub-zero temperatures. The overall conclusion of this investigation\nis that water's hydrogen bond strength is poised centrally within a narrow\nwindow of its suitability for life."
    },
    {
        "anchor": "The effect of thermal history on the atomic structure and mechanical\n  properties of amorphous alloys: The influence of thermal processing on the potential energy, atomic\nstructure, and mechanical properties of metallic glasses is examined using\nmolecular dynamics simulations. We study the three-dimensional binary mixture,\nwhich was first relaxed near the glass transition temperature, and then rapidly\ncooled deep into the glass phase. It was found that glasses prepared at higher\nannealing temperatures are relocated to higher energy states and their average\nglass structure remains more disordered, as reflected in the shape of the pair\ncorrelation function. The results of mechanical testing demonstrate that both\nthe shear modulus and yielding peak increase significantly when the annealing\ntemperature approaches $T_g$ from above. Moreover, the shear modulus becomes a\nstrong function of strain rate only for samples equilibrated at sufficiently\nhigh temperatures. Based on the spatial distribution of nonaffine\ndisplacements, we show that the deformation mode changes from brittle to\nductile upon increasing annealing temperature. These results can be useful for\nthe design and optimization of the fabrication processes of bulk glassy alloys\nwith improved plasticity.",
        "positive": "Glassy, Gardner-like Phenomenology in Minimally Polydisperse Crystalline\n  Systems: We report on a non-equilibrium phase of matter, the minimally disordered\ncrystal phase, which we find exists between the maximally amorphous glasses and\nthe ideal crystal. Even though these near crystals appear highly ordered, they\ndisplay glassy and jamming features akin to those observed in amorphous solids.\nStructurally, they exhibit a power-law scaling in their probability\ndistribution of weak forces and small interparticle gaps as well as a flat\ndensity of vibrational states. Dynamically, they display anomalous aging above\na characteristic pressure. Quantitatively this disordered crystal phase has\nmuch in common with the Gardner-like phase seen in maximally disordered solids.\nNear crystals should be amenable to experimental realizations in\ncommercially-available particulate systems and are to be indispensable in\nverifying the theory of amorphous materials."
    },
    {
        "anchor": "Structure and phase equilibria of the Widom-Rowlinson model: The Widom-Rowlinson model plays an important role in the statistical\nmechanics of second order phase transitions and yet there currently exists no\ntheoretical approach capable of accurately predicting both the microscopic\nstructure and phase equilibria. We address this issue using computer\nsimulation, density functional theory and integral equation theory. A detailed\nstudy of the pair correlation functions obtained from computer simulation\nmotivates a closure of the Ornstein-Zernike equations which gives a good\ndescription of the pair structure and locates the critical point to an accuracy\nof 2 percent.",
        "positive": "Capillary action in scalar active matter: We study the capacity of active matter to rise in thin tubes against gravity\nand other related phenomena, like, wetting of vertical plates and spontaneous\nimbibition, where a wetting liquid is drawn into a porous medium. This\ncapillary action or capillarity is well known in classical fluids and\noriginates from attractive interactions between the liquid molecules and the\ncontainer walls, and from the attraction of the liquid molecules among each\nother. We observe capillarity in a minimal model for scalar active matter with\npurely repulsive interactions, where an effective attraction emerges due to\nslowdown during collisions between active particles and between active\nparticles and walls. Simulations indicate that the capillary rise in thin tubes\nis approximately proportional to the active sedimentation length $\\lambda$ and\nthat the wetting height of a vertical plate grows superlinear with $\\lambda$.\nIn a disordered porous medium the imbibition height scales as $\\langle\nh\\rangle\\propto\\lambda\\phi_m$, where $\\phi_m$ is its packing fraction."
    },
    {
        "anchor": "Can a double stranded DNA be unzipped by pulling a single strand?:\n  Phases of adsorbed DNA: We study the unzipping of a double stranded DNA (dsDNA) by applying an\nexternal force on a single strand while leaving the other strand free. We find\nthat the dsDNA can be unzipped to two single strands if the external force\nexceeds a critical value. We obtain the phase diagram which is found to be\ndifferent from the phase diagram of unzipping by pulling both the strands in\nopposite directions. In the presence of an attractive surface near DNA, the\nphase diagram gets modified drastically and shows richer surprises including a\ncritical end point and a triple point.",
        "positive": "Polymer reptation and nucleosome repositioning: We consider how beads can diffuse along a chain that wraps them, without\nbecoming displaced from the chain; our proposed mechanism is analogous to the\nreptation of \"stored length\" in more familiar situations of polymer dynamics.\nThe problem arises in the case of globular aggregates of proteins (histones)\nthat are wound by DNA in the chromosomes of plants and animals; these beads\n(nucleosomes) are multiply wrapped and yet are able to reposition themselves\nover long distances, while remaining bound by the DNA chain."
    },
    {
        "anchor": "Hydrophobic interactions: an overview: We present an overview of the recent progress that has been made in\nunderstanding the origin of hydrophobic interactions. We discuss the different\ncharacter of the solvation behavior of apolar solutes at small and large length\nscales. We emphasize that the crossover in the solvation behavior arises from a\ncollective effect, which means that implicit solvent models should be used with\ncare. We then discuss a recently developed explicit solvent model, in which the\nsolvent is not described at the atomic level, but rather at the level of a\ndensity field. The model is based upon a lattice-gas model, which describes\ndensity fluctuations in the solvent at large length scales, and a Gaussian\nmodel, which describes density fluctuations at smaller length scales. By\nintegrating out the small length scale field, a Hamiltonian is obtained, which\nis a function of the binary, large-length scale field only. This makes it\npossible to simulate much larger systems than hitherto possible as demonstrated\nby the application of the model to the collapse of an ideal hydrophobic\npolymer. The results show that the collapse is dominated by the dynamics of the\nsolvent, in particular the formation of a vapor bubble of critical size.\nImplications of these findings to the understanding of pressure denaturation of\nproteins are discussed.",
        "positive": "Adsorption of annealed branched polymers on curved surfaces: The behavior of annealed branched polymers near adsorbing surfaces plays a\nfundamental role in many biological and industrial processes. Most importantly\nsingle stranded RNA in solution tends to fold up and self-bind to form a highly\nbranched structure. Using a mean field theory, we both perturbatively and\nnumerically examine the adsorption of branched polymers on surfaces of several\ndifferent geometries in a good solvent. Independent of the geometry of the\nwall, we observe that as branching density increases, surface tension\ndecreases. However, we find a coupling between the branching density and\ncurvature in that a further lowering of surface tension occurs when the wall\ncurves towards the polymer, but the amount of lowering of surface tension\ndecreases when the wall curves away from the polymer. We find that for branched\npolymers confined into spherical cavities, most of branch-points are located in\nthe vicinity of the interior wall and the surface tension is minimized for a\ncritical cavity radius. For branch polymers next to sinusoidal surfaces, we\nfind that branch-points accumulate at the valleys while end-points on the\npeaks."
    },
    {
        "anchor": "From rods to helices: evidence of a screw-like nematic phase: Evidence of a special chiral nematic phase is provided using numerical\nsimulation and Onsager theory for systems of hard helical particles. This phase\nappears at the high density end of the nematic phase, when helices are well\naligned, and is characterized by the C$_2$ symmetry axes of the helices\nspiraling around the nematic director with periodicity equal to the particle\npitch. This coupling between translational and rotational degrees of freedom\nallows a more efficient packing and hence an increase of translational entropy.\nSuitable order parameters and correlation functions are introduced to identify\nthis screw-like phase, whose main features are then studied as a function of\nradius and pitch of the helical particles. Our study highlights the physical\nmechanism underlying a similar ordering observed in colloidal helical flagella\n[E. Barry et al. \\textit{Phys. Rev. Lett.} \\textbf{96}, 018305 (2006)] and\nraises the question of whether it could be observed in other helical particle\nsystems, such as DNA, at sufficiently high densities.",
        "positive": "Simulation of fluid-solid coexistence in finite volumes: A method to\n  study the properties of wall-attached crystalline nuclei: The Asakura-Oosawa model for colloid-polymer mixtures is studied by Monte\nCarlo simulations at densities inside the two-phase coexistence region of fluid\nand solid. Choosing a geometry where the system is confined between two flat\nwalls, and a wall-colloid potential that leads to incomplete wetting of the\ncrystal at the wall, conditions can be created where a single nanoscopic\nwall-attached crystalline cluster coexists with fluid in the remainder of the\nsimulation box. Following related ideas that have been useful to study\nheterogeneous nucleation of liquid droplets at the vapor-liquid coexistence, we\nestimate the contact angles from observations of the crystalline clusters in\nthermal equilibrium. We find fair agreement with a prediction based on Young's\nequation, using estimates of interface and wall tension from the study of flat\nsurfaces. It is shown that the pressure versus density curve of the finite\nsystem exhibits a loop, but the pressure maximum signifies the \"droplet\nevaporation-condensation\" transition and thus has nothing in common with a van\nder Waals-like loop. Preparing systems where the packing fraction is deep\ninside the two-phase coexistence region, the system spontaneously forms a \"slab\nstate\", with two wall-attached crystalline domains separated by (flat)\ninterfaces from liquid in full equilibrium with the crystal in between;\nanalysis of such states allows a precise estimation of the bulk equilibrium\nproperties at phase coexistence."
    },
    {
        "anchor": "Microgels at interfaces behave as 2D elastic particles featuring\n  reentrant dynamics: Soft colloids are increasingly used as model systems to address fundamental\nissues such as crystallisation and the glass and jamming transitions. Among the\navailable classes of soft colloids, microgels are emerging as the gold\nstandard. Since their great internal complexity makes their theoretical\ncharacterization very hard, microgels are commonly modelled, at least in the\nsmall-deformation regime, within the simple framework of linear elasticity\ntheory. Here we show that there exist conditions where its range of validity\ncan be greatly extended, providing strong numerical evidence that microgels\nadsorbed at an interface follow the two-dimensional Hertzian theory, and hence\nbehave like 2D elastic particles, up to very large deformations, in stark\ncontrast to what found in bulk conditions. We are also able to estimate the\nYoung's modulus of the individual particles and, by comparing it with its\ncounterpart in bulk conditions, we demonstrate a significant stiffening of the\npolymer network at the interface. Finally, by analyzing dynamical properties,\nwe predict multiple reentrant phenomena: by a continuous increase of particle\ndensity, microgels first arrest and then re-fluidify due to the high\npenetrability of their extended coronas. We observe this anomalous behavior in\na range of experimentally accessible conditions for small and loosely\ncrosslinked microgels. The present work thus establishes microgels at\ninterfaces as a new model system for fundamental investigations, paving the way\nfor the experimental synthesis and research on unique high-density liquidlike\nstates. In addition, these results can guide the development of novel assembly\nand patterning strategies on surfaces and the design of novel materials with\ndesired interfacial behavior.",
        "positive": "Structural and topological changes across the liquid-liquid transition\n  in water: It has recently been shown that the TIP4P/Ice model of water can be studied\nnumerically in metastable equilibrium at and below its liquid-liquid critical\ntemperature. We report here simulations along a subcritical isotherm, for which\ntwo liquid states with the same pressure and temperature, but different\ndensity, can be equilibrated. This allows for a clear visualisation of the\nstructural changes taking place across the transition. We specifically focus on\nhow the topological properties of the H-bond network change across the\nliquid-liquid transition. Our results demonstrate that the structure of the\nhigh-density liquid, characterised by the existence of interstitial molecules\nand commonly explained in terms of the collapse of the second neighbour shell,\nactually originates from the folding back of long rings, bringing pairs of\nmolecules separated by several hydrogen-bonds close by in space."
    },
    {
        "anchor": "Buckling and competition of energy and entropy lead conformation of\n  single-walled carbon nanocones: Using a continuum model, expressions for the elastic energy, defect energy,\nstructure entropy, and mixing entropy of carbon nanocones are proposed\nanalytically. The optimal conformation of carbon nanocones is studied by\nimposing minimization of free energy and analyzing the effects that the\nbuckling of a nanocone's walls have during formation. The model explains the\nexperimentally observed preference of 19.2 degrees for the cone angle of carbon\nnanocone. Furthermore, it predicts the optimal conformation of carbon nanocones\nto result in a cone angle of 19.2 degrees, radius of 0.35 nm, and critical\nlength of 24 nm, all of which agree very well with experimental observations.",
        "positive": "Designing Phononic Band Gaps with Sticky Potentials: Spectral gaps in the vibrational modes of disordered solids are key design\nelements in the synthesis and control of phononic metamaterials that exhibit a\nplethora of novel elastic and mechanical properties. However, reliably\nproducing these gaps often require a high degree of network specificity through\ncomplex control optimization procedures. In this work, we present as an\nadditional tool to the existing repertoire, a numerical scheme that rapidly\ngenerates sizeable spectral gaps in absence of any fine tuning of the network\nstructure or elastic parameters. These gaps occur even in disordered\npolydisperse systems consisting of relatively few particles ($N \\sim\n10^2-10^3$). Our proposed procedure exploits sticky potentials that have\nrecently been shown to suppress the formation of soft modes, thus effectively\nrecovering the linear elastic regime where band structures appear, at much\nshorter length scales than in conventional models of disordered solids. Our\napproach is relevant to design and realization of gapped spectra in a variety\nof physical setups ranging from colloidal suspensions to 3D-printed elastic\nnetworks."
    },
    {
        "anchor": "Ultrafast ultrasonic imaging coupled to rheometry: principle and\n  illustration: We describe a technique coupling standard rheology and ultrasonic imaging\nwith promising applications to characterization of soft materials under shear.\nPlane wave imaging using an ultrafast scanner allows to follow the local\ndynamics of fluids sheared between two concentric cylinders with frame rates as\nhigh as 10,000 images per second, while simultaneously monitoring the shear\nrate, shear stress, and viscosity as a function of time. The capacities of this\n\"rheo-ultrasound\" instrument are illustrated on two examples: (i) the classical\ncase of the Taylor-Couette instability in a simple viscous fluid and (ii) the\nunstable shear-banded flow of a non-Newtonian wormlike micellar solution.",
        "positive": "Unusual Transition Patterns in Bose-Einstein Condensation: We analyze the possible transition patterns exhibited by an effective\nnon-relativistic field model describing interacting binary homogeneous dilute\nBose gases whose overall potential is repulsive. We evaluate the temperature\ndependence of all couplings and show that at intermediate temperatures the\ncrossed interaction, which is allowed to be attractive, dominates, leading to\nsmooth re-entrant phases. At higher temperatures this interaction suffers a\nsudden sign inversion leading to an abrupt discontinuous transition back to the\nnormal gas phase. This situation may suggest an alternative way to observe\ncollapsing and exploding condensates. Our results also suggest that such binary\nsystems may offer the possibility of observing Bose-Einstein condensation at\nhigher critical temperatures."
    },
    {
        "anchor": "Hydrodynamics interactions of clusters of drops: a study of the\n  coalescence phenomena with the finite volume method: In this work has been proposed a numerical scheme with the aim of simulate\nthe coalescence process between water drops immersed in a continuous phase\n(n-heptane). This numerical scheme is based in the Finite Volume method and two\ndifferent values for the initial velocity of the drops were chosen. Depending\nof the initial velocity of collision some scenarios emerge, such as: permanent\ncoalescence, formation of satellite drops etc. For some snap shots the\nstreamlines are calculated for the different process of permanent coalescence.\nThese streamlines allow the understanding of the dynamics of the droplets\nimmersed on the n-heptane phase. The model used for the surface tension is\npresented and its effects on the dynamics of coalescence of the droplets are\nshowed, which after some time tends to the spherical form.",
        "positive": "Landscape-Inversion Phase Transition in Dipolar Colloids: Tuning the\n  Structure and Dynamics of 2D Crystals: We study the 2D crystalline phases of paramagnetic colloidal particles with\ndipolar interactions and constrained on a periodic substrate. Combining theory,\nsimulation, and experiments we demonstrate a new scenario of first-order phase\ntransitions that occurs via a complete inversion of the energy landscape,\nfeaturing non-conventional properties that allow for: (i) tuning of crystal\nsymmetry; (ii) control of dynamical properties of different crystalline orders\nvia tuning of their relative stability with an external magnetic field; (iii)\nan equivalent but independent control of the same dynamic properties via\ntemporal modulations of that field; and (iv) non-standard phase-ordering\nkinetics involving spontaneous formation of transient metastable domains."
    },
    {
        "anchor": "Ultrafiltration of charge-stabilized dispersions at low salinity: We present a comprehensive study of cross-flow ultrafiltration (UF) of\ncharge-stabilized suspensions, under low-salinity conditions of\nelectrostatically strongly repelling colloidal particles. The axially varying\npermeate flux, near-membrane concentration-polarization (CP) layer and osmotic\npressure profiles are calculated using a macroscopic diffusion-advection\nboundary layer method, and are compared with filtration experiments on aqueous\nsuspensions of charge-stabilized silica particles. The theoretical description\nbased on the one-component macroion fluid model (OCM) accounts for the strong\ninfluence of surface-released counterions on the renormalized colloid charge\nand suspension osmotic compressibility, and for the influence of the colloidal\nhydrodynamic interactions and electric double layer repulsion on the\nconcentration-dependent suspension viscosity $\\eta$, and collective diffusion\ncoefficient $D_c$. A strong electro-hydrodynamic enhancement of $D_c$ and\n$\\eta$, and likewise of the osmotic pressure is predicted theoretically, as\ncompared with their values for a hard-sphere suspension. We also point to the\nfailure of generalized Stokes-Einstein relations describing reciprocal\nrelations between $D_c$ and $\\eta$. According to our filtration model, $D_c$ is\nof dominant influence, giving rise to an only weakly developed CP layer having\npractically no effect on the permeate flux. This prediction is quantitatively\nconfirmed by our UF measurements of the permeate flux using an aqueous\nsuspension of charged silica spheres as the feed system. The experimentally\ndetected fouling for the largest considered transmembrane pressure values is\nshown not to be due to filter cake formation by crystallization or\nvitrification.",
        "positive": "Smectic ordering in liquid crystal - aerosil dispersions I. X-ray\n  scattering: Comprehensive x-ray scattering studies have characterized the smectic\nordering of octylcyanobiphenyl (8CB) confined in the hydrogen-bonded silica\ngels formed by aerosil dispersions. For all densities of aerosil and all\nmeasurement temperatures, the correlations remain short range, demonstrating\nthat the disorder imposed by the gels destroys the nematic (N) to smectic-A\n(SmA) transition. The smectic correlation function contains two distinct\ncontributions. The first has a form identical to that describing the critical\nthermal fluctuations in pure 8CB near the N-SmA transition, and this term\ndisplays a temperature dependence at high temperatures similar to that of the\npure liquid crystal. The second term, which is negligible at high temperatures\nbut dominates at low temperatures, has a shape given by the thermal term\nsquared and describes the static fluctuations due to random fields induced by\nconfinement in the gel. The correlation lengths appearing in the thermal and\ndisorder terms are the same and show strong variation with gel density at low\ntemperatures. The temperature dependence of the amplitude of the static\nfluctuations further suggests that nematic susceptibility become suppressed\nwith increasing quenched disorder. The results overall are well described by a\nmapping of the liquid crystal-aerosil system into a three dimensional XY model\nin a random field with disorder strength varying linearly with the aerosil\ndensity."
    },
    {
        "anchor": "Spherical Foams in Flat Space: Regular tesselations of space are characterized through their Schlafli\nsymbols {p,q,r}, where each cell has regular p-gonal sides, q meeting at each\nvertex, and r meeting on each edge. Regular tesselations with symbols {p,3,3}\nall satisfy Plateau's laws for equilibrium foams. For general p, however, these\nregular tesselations do not embed in Euclidean space, but require a uniform\nbackground curvature. We study a class of regular foams on S^3 which, through\nconformal, stereographic projection to R^3 define irregular cells consistent\nwith Plateau's laws. We analytically characterize a broad classes of bulk foam\nbubbles, and extend and explain recent observations on foam structure and shape\ndistribution. Our approach also allows us to comment on foam stability by\nidentifying a weak local maximum of A^(3/2)/V at the maximally symmetric\ntetrahedral bubble that participates in T2 rearrangements.",
        "positive": "Active turbulence in active nematics: Dense, active systems show active turbulence, a state characterised by flow\nfields that are chaotic, with continually changing velocity jets and swirls.\nHere we review our current understanding of active turbulence. The development\nis primarily based on the theory and simulations of active liquid crystals, but\nwith accompanying summaries of related literature."
    },
    {
        "anchor": "Colloidal particle adsorption at water/water interfaces with ultra-low\n  interfacial tension: Using fluorescence microscopy we study the adsorption of single latex\nmicroparticles at a water/water interface between demixing aqueous solutions of\npolymers, generally known as a water-in-water emulsion. Similar microparticles\nat the interface between molecular liquids have exhibited an extremely slow\nrelaxation preventing the observation of expected equilibrium states. This\nphenomenon has been attributed to \"long-lived\" metastable states caused by\nsignificant energy barriers $\\Delta{\\cal F}\\sim \\gamma A_d\\gg k_B T$ induced by\nhigh interfacial tension ($\\gamma \\sim 10^{-2}$ N/m) and nanoscale surface\ndefects with characteristic areas $A_d \\simeq$ 10--30 nm$^2$. For the studied\nwater/water interface with ultra-low surface tension ($\\gamma \\sim 10^{-4}$\nN/m) we are able to characterize the entire adsorption process and observe\nequilibrium states prescribed by a single equilibrium contact angle independent\nof the particle size. Notably, we observe crossovers from fast initial dynamics\nto slower kinetic regimes analytically predicted for large surface defects\n($A_d \\simeq$ 500 nm$^2$). Moreover, particle trajectories reveal a\nposition-independent damping coefficient that is unexpected given the large\nviscosity contrast between phases. These observations are attributed to the\nremarkably diffuse nature of the water/water interface and the adsorption and\nentanglement of polymer chains in the semidilute solutions. This work offers\nsome first insights on the adsorption dynamics/kinetics of microparticles at\nwater/water interfaces in bio-colloidal systems.",
        "positive": "Shear thickening and migration in granular suspensions: We study the emergence of shear thickening in dense suspensions of\nnon-Brownian particles. We combine local velocity and concentration\nmeasurements using Magnetic Resonance Imaging with macroscopic rheometry\nexperiments. In steady state, we observe that the material is heterogeneous,\nand we find that that the local rheology presents a continuous transition at\nlow shear rate from a viscous to a shear thickening, Bagnoldian, behavior with\nshear stresses proportional to the shear rate squared, as predicted by a\nscaling analysis. We show that the heterogeneity results from an unexpectedly\nfast migration of grains, which we attribute to the emergence of the Bagnoldian\nrheology. The migration process is observed to be accompanied by macroscopic\ntransient discontinuous shear thickening, which is consequently not an\nintrinsic property of granular suspensions."
    },
    {
        "anchor": "Engineered optical nonlinearities and enhanced light transmission in\n  soft-matter systems with tunable polarizabilities: In this work, we demonstrate that the nonlinear response of certain\nsoft-matter systems can be tailored at will by appropriately engineering their\noptical polarizability. In particular, we deliberately synthesize stable\ncolloidal suspensions with negative polarizabilities, and observe for the first\ntime robust propagation and enhanced transmission of self-trapped light over\nlong distances that would have been otherwise impossible in conventional\nsuspensions with positive polarizabilities. What greatly facilitates this\nbehavior is an induced saturable nonlinear optical response introduced by the\nthermodynamic properties of these colloidal systems. This in turn leads to a\nsubstantial reduction in scattering via self-activated transparency effects.\nOur results may open up new opportunities in developing soft-matter systems\nwith tunable optical nonlinearities.",
        "positive": "Strand plasticity governs fatigue in colloidal gels: Repeated loading of a solid leads to microstructural damage that ultimately\nresults in catastrophic material failure. While posing a major threat to the\nstability of virtually all materials, the microscopic origins of fatigue,\nespecially for soft solids, remain elusive. Here we explore fatigue in\ncolloidal gels as prototypical inhomogeneous soft solids by combining\nexperiments and computer simulations. Our results reveal how mechanical loading\nleads to irreversible strand stretching, which builds slack into the network\nthat softens the solid at small strains and causes strain hardening at larger\ndeformations. We thus find that microscopic plasticity governs fatigue at much\nlarger scales. This gives rise to a new picture of fatigue in soft thermal\nsolids and calls for new theoretical descriptions of soft gel mechanics in\nwhich local plasticity is taken into account."
    },
    {
        "anchor": "Surface flow profiles for dry and wet granular materials by Particle\n  Tracking Velocimetry; the effect of wall roughness: Two-dimensional Particle Tracking Velocimetry (PTV) is a promising technique\nto study the behaviour of granular flows. The aim is to experimentally\ndetermine the free surface width and position of the shear band from the\nvelocity profile to validate simulations in a split-bottom shear cell geometry.\nThe position and velocities of scattered tracer particles are tracked as they\nmove with the bulk flow by analyzing images. We then use a new technique to\nextract the continuum velocity field, applying coarse-graining with the\npostprocessing toolbox MercuryCG on the discrete experimental PTV data. For\nintermediate filling heights, the dependence of the shear (or angular) velocity\non the radial coordinate at the free surface is well fitted by an error\nfunction. From the error function, we get the width and the centre position of\nthe shear band. We investigate the dependence of these shear band properties on\nfilling height and rotation frequencies of the shear cell for dry glass beads\nfor rough and smooth wall surfaces. For rough surfaces, the data agrees with\nthe existing experimental results and theoretical scaling predictions. For\nsmooth surfaces, particle-wall slippage is significant and the data deviates\nfrom the predictions. We further study the effect of cohesion on the shear band\nproperties by using small amount of silicon oil and glycerol as interstitial\nliquids with the glass beads. While silicon oil does not lead to big changes,\nglycerol changes the shear band properties considerably. The shear band gets\nwider and is situated further inward with increasing liquid saturation, due to\nthe correspondingly increasing trend of particles to stick together.",
        "positive": "Confinement Effect on Thermopower of Electrolytes: Ionic Seebeck effect of electrolytes has shown promising applications in\nharvesting energy from low-grade waste-heat sources with small temperature\ndifference from the environment, which can power sensors and Internet-of-Things\ndevices. Recent experiments have demonstrated giant thermopower (~ 10 mV/K) of\nelectrolytes under confinement due to the overlapping of electric double layer\n(EDL). Nonetheless, there has been no consensus on the theory of the ionic\nSeebeck effect, especially whether the thermopower depends on ionic\ndiffusivities, imposing confusion on the theoretical interpretation of\nexperimental discovery on giant thermopower of confined electrolytes. This\narticle presents a linear perturbative solution of Poisson-Nernst-Planck (PNP)\nequations to describe the ionic Seebeck effect of confined liquid electrolytes.\nWe provide both analytical and numerical solutions to the PNP equations for\nclosed systems and open systems connected to reservoirs of electrolytes. The\nanalytical solution captured the confinement effect both along and\nperpendicular to the temperature gradient, and showed excellent agreement with\nnumerically solved PNP equations for a wide range of EDL potentials, channel\nwidths, and lengths. Finally, we show that for polyelectrolytes with largely\nmismatched diffusivities, thermopower can only be enhanced for closed system\nthrough confinement perpendicular to the temperature gradient."
    },
    {
        "anchor": "An effective potential for one-dimensional matter-wave solitons in an\n  axially inhomogeneous trap: We demonstrate that a tight transverse trap with the local frequency, $%\n\\omega_{\\perp}$, gradually varying in the longitudinal direction ($x$) induces\nan effective potential for one-dimensional solitons in a self-attractive\nBose-Einstein condensate. An analytical approximation for this potential is\nderived by means of a variational method. In the lowest approximation, the\npotential is $N(S+1)\\omega_{\\perp}(x)$, with $N$ the soliton's norm (number of\natoms), and $S$ its intrinsic vorticity (if any). The results can be used to\ndevise nonuniform traps helping to control the longitudinal dynamics of the\nsolitons. Numerical verification of the analytical predictions will be\npresented elsewhere.",
        "positive": "When does Wenzel's extension of Young's equation for the contact angle\n  of droplets apply? A density functional study: he contact angle of a liquid droplet on a surface under partial wetting\nconditions differs for a nanoscopically rough or periodically corrugated\nsurface from its value for a perfectly flat surface. Wenzel's relation\nattributes this difference simply to the geometric magnification of the surface\narea (by a factor $r_{\\rm w}$), but the validity of this idea is controversial.\nWe elucidate this problem by model calculations for a sinusoidal corrugation of\nthe form $z_{\\rm wall}(y) = \\Delta\\cos(2\\pi y/\\lambda)$ , for a potential of\nshort range $\\sigma_{\\rm w}$ acting from the wall on the fluid particles. When\nthe vapor phase is an ideal gas, the change of the wall-vapor surface tension\ncan be computed exactly, and corrections to Wenzel's equation are typically of\norder $\\sigma_{\\rm w}\\Delta/\\lambda^2$. For fixed $r_{\\rm w}$ and fixed\n$\\sigma_{\\rm w}$ the approach to Wenzel's result with increasing $\\lambda$ may\nbe nonmonotonic and this limit often is only reached for $\\lambda/\\sigma_{\\rm\nw}>30$. For a non-additive binary mixture, density functional theory is used to\nwork out the density profiles of both coexisting phases both for planar and\ncorrugated walls, as well as the corresponding surface tensions. Again,\ndeviations from Wenzel's results of similar magnitude as in the above ideal gas\ncase are predicted. Finally, a crudely simplified description based on the\ninterface Hamiltonian concept is used to interpret corresponding simulation\nresults along similar lines. Wenzel's approach is found to generally hold when\n$\\lambda/\\sigma_{\\rm w}\\gg 1$, $\\Delta/\\lambda<1$, and conditions avoiding\nproximity of wetting or filling transitions."
    },
    {
        "anchor": "Orientational Memory of Active Particles in Multistate Non-Markovian\n  Processes: The orientational memory of particles can serve as an effective measure of\ndiffusivity, spreading, and search efficiency in complex stochastic processes.\nWe develop a theoretical framework to describe the decay of directional\ncorrelations in a generic class of stochastic active processes consisting of\ndistinct states of motion characterized by their persistence and switching\nprobabilities between the states. For exponentially distributed sojourn times,\nthe orientation autocorrelation is analytically derived and the characteristic\ntimes of its crossovers are obtained in terms of the persistence of each state\nand the switching probabilities. We show how non-exponential sojourn-time\ndistributions of interest, such as Gaussian and power-law distributions, can\nresult from history-dependent transitions between the states. The relaxation\nbehavior of the correlation function in such non-Markovian processes is\ngoverned by the history-dependence of the switching probabilities and cannot be\nsolely determined by the mean sojourn times of the states.",
        "positive": "Stabilizing the Discrete Vortex of Topological Charge S=2: We study the instability of the discrete vortex with topological charge S=2\nin a prototypical lattice model and observe its mediation through the central\nlattice site. Motivated by this finding, we analyze the model with the central\nsite being inert. We identify analytically and observe numerically the\nexistence of a range of linearly stable discrete vortices with S=2 in the\nlatter model. The range of stability is comparable to that of the recently\nobserved experimentally S=1 discrete vortex, suggesting the potential for\nobservation of such higher charge discrete vortices."
    },
    {
        "anchor": "Correlations in atomic systems: Diagnosing coherent superpositions: While investigating quantum correlations in atomic systems, we note that\nsingle measurements contain information about these correlations. Using a\nsimple model of measurement -- analogous to the one used in quantum optics --\nwe show how to extract higher order correlation functions from individual\n\"phtotographs\" of the atomic sample. As a possible application we apply the\nmethod to detect a subtle phase coherence in mesoscopic superpostitions.",
        "positive": "Nonlinear Elasticity of Flow-Stabilized Solids: Thermal fluctuations, geometric exclusion, and external driving all govern\nthe mechanical response of dense particulate suspensions. Here, we measure the\nstress-strain response of quasi-two-dimensional flow-stabilized microsphere\nheaps in a regime in which all three effects are present using a microfluidic\ndevice. We observe that the elastic modulus and the mean interparticle\nseparation of the heaps are tunable via the confining stress provided by the\nfluid flow. Furthermore, the measured stress-strain curves exhibit a universal\nnonlinear shape which can be predicted from a thermal van der Waals equation of\nstate with excluded volume. This analysis indicates that many-body interactions\ncontribute a significant fraction of the stress supported by the heap."
    },
    {
        "anchor": "Stationary particle currents in sedimenting active matter wetting a wall: Recently it was predicted, on the basis of a lattice gas model, that scalar\nactive matter in a gravitational field would rise against gravity up a\nconfining wall or inside a thin capillary - in spite of repulsive particle-wall\ninteractions [Phys. Rev. Lett. 124, 048001 (2020)]. In this paper we confirm\nthis prediction with sedimenting active Brownian particles (ABPs) in a box\nnumerically and elucidate the mechanism leading to the formation of a meniscus\nrising above the bulk of the sedimentation region. The height of the meniscus\nincreases with the activity of the system, algebraically with the P\\'eclet\nnumber. The formation of the meniscus is determined by a stationary circular\nparticle current, a vortex, centered at the base of the meniscus, whose size\nand strength increase with the ABP activity. The origin of these vortices can\nbe traced back to the confinement of the ABPs in a box: already the stationary\nstate of ideal (non-interacting) ABPs without gravitation displays circular\ncurrents that arrange in a highly symmetric way in the eight octants of the\nbox. Gravitation distorts this vortex configuration downward, leaving two major\nvortices at the two side walls, with a strong downward flow along the walls.\nRepulsive interactions between the ABPs change this situation only as soon as\nmotility induced phase separation (MIPS) sets in and forms a dense, sedimented\nliquid region at the bottom, which pushes the center of the vortex upwards\ntowards the liquid-gas interface. Self-propelled particles therefore represent\nan impressive realization of scalar active matter that forms stationary\nparticle currents being able to perform visible work against gravity or any\nother external field, which we predict to be observable experimentally in\nactive colloids under gravitation.",
        "positive": "Crowding induced clustering under confinement: We present Langevin dynamics simulations that study the collective behavior\nof driven particles embedded in a densely packed background consisting of\npassive particles. Depending on the driving force, the densities of driven and\npassive particles, and the temperature we observe a dynamical phase separation\nof the driven particles, which cluster together in tight bands. We explore the\nmechanisms that drive this cluster formation, and determine the critical\nconditions for such phase separation. A simple physical picture explains the\nformation and subsequent growth of a jammed zone developing in front of the\ndriven cluster. The model correctly captures the observed scaling with time. We\nanalyze the implications of this clustering transition for the driven transport\nin dense particulate flows, which due to a non-monotonic dependence on the\napplied driving force is not straightforwardly optimized. We provide\nproof-of-concept for a direct application of the clustering effect, and propose\na 'colloidal chromatograph'; a setup that permits the separation of colloids by\nmass or size."
    },
    {
        "anchor": "Harvesting information to control non-equilibrium states of active\n  matter: We propose to use a correlated noise bath to drive an optically trapped\nBrownian particle that mimics active biological matter. Thanks to the\nflexibility and precision of our setup, we are able to control the different\nparameters that drive the stochastic motion of the particle with unprecedented\naccuracy, thus reaching strongly correlated regimes that are not easily\naccessible with real active matter. In particular, by using the correlation\ntime (i.e., the \"color\") of the noise as a control parameter, we can trigger\ntransitions between two non-equilibrium steady states with no expended work,\nbut only a calorific cost. Remarkably, the measured heat production is directly\nproportional to the spectral entropy of the correlated noise, in a fashion that\nis reminiscent of Landauer's principle. Our procedure can be viewed as a method\nfor harvesting information from the active fluctuations.",
        "positive": "The glass susceptibility: growth kinetics and saturation under shear: We study the growth kinetics of glassy correlations in a structural glass by\nmonitoring the evolution, within mode-coupling theory, of a suitably defined\nthree-point function $\\chi_C(t,t_w)$ with time $t$ and waiting time $t_w$. From\nthe complete wave vector-dependent equations of motion for domain growth we\npass to a schematic limit to obtain a numerically tractable form. We find that\nthe peak value $\\chi_C^P$ of $\\chi_C(t,t_w)$, which can be viewed as a\ncorrelation volume, grows as $t_w^{0.5}$, and the relaxation time as\n$t_w^{0.8}$, following a quench to a point deep in the glassy state. These\nresults constitute a theoretical explanation of the simulation findings of\nParisi [J. Phys. Chem. B {\\bf 103}, 4128 (1999)] and Kob and Barrat [Phys. Rev.\nLett. {\\bf 78}, 4581 (1997)] and are also in qualitative agreement with\nParsaeian and Castillo [Phys. Rev. E {\\bf 78}, 060105(R) (2008)]. On the other\nhand, if the quench is to a point on the {\\em liquid side}, the correlation\nvolume grows to saturation. We present a similar calculation for the growth\nkinetics in a $p$-spin spin glass mean-field model where we find a slower\ngrowth, $\\chi_C^P \\sim t_w^{0.13}$. Further, we show that a shear rate $\\gdot$\ncuts off the growth of glassy correlations when $t_w\\sim 1/\\gdot$ for quench in\nthe glassy regime and $t_w=\\min(t_r,1/\\gdot)$ in the liquid, where $t_r$ is the\nrelaxation time of the unsheared liquid. The relaxation time of the steady\nstate fluid in this case is $\\propto \\gdot^{-0.8}$."
    },
    {
        "anchor": "Shear Reversal in Dense Suspensions: The Challenge to Fabric Evolution\n  Models from Simulation Data: Despite the industrial importance of dense suspensions of hard particles, few\nconstitutive models for them have been proposed or tested. Most of these are\neffectively \"fabric evolution models\" (FEMs) based on a stress rule connecting\nthe bulk stress to a rank-2 microstructural fabric tensor Q and a closed\ntime-evolution equation for Q. In dense suspensions most of the stress comes\nfrom short-ranged pairwise steric or lubrication interactions at near-contacts,\nso a natural choice for Q is the deviatoric 2nd moment of the distribution P(p)\nof the near-contact orientations p. Here we test directly whether a closed\ntime-evolution equation for such a Q can exist for inertialess non-Brownian\nhard spheres in a Newtonian solvent. We perform extensive numerical simulations\nfor the evolution of P(p) under shear reversal, providing a stringent test for\nFEMs. We consider a generic class of these as defined by Hand (1962)\nconstrained only by frame indifference. Motivated by the small microstructural\nanisotropy in the dense regime, we start with linear models and successively\nconsider increasingly nonlinear ones. Based on these results we suggest that no\nclosed FEM properly describes the dynamics of Q under reversal. We attribute\nthis to the fact that Q gives a poor description of the microstructure during\nlarge parts of the microstructural evolution following shear reversal.\nSpecifically, the truncation of P(p) at 2nd spherical harmonic level describes\ntwo-lobed distributions of near-contact orientations, whereas on reversal we\nobserve distributions that are markedly four-lobed; moreover dP/dt (p) has\noblique axes, not collinear with those of Q in the shear plane. This structure\nlikely precludes any adequate closure at second-rank level. Instead, our\nnumerical data suggest that closures involving the coupled evolution of both a\nfabric tensor and a fourth-rank tensor might be reasonably accurate.",
        "positive": "Suppression of crystalline fluctuations by competing structures in a\n  supercooled liquid: We propose a geometrical characterization of amorphous liquid structures that\nsuppress crystallization by competing locally with crystalline order. We\nintroduce for this purpose the crystal affinity of a liquid, a simple measure\nof its propensity to accumulate local crystalline structures on cooling. This\nquantity is explicitly related to the high temperature structural covariance\nbetween local fluctuations in crystal order and that of competing liquid\nstructures: favouring a structure that, due to poor overlap properties,\nanticorrelates with crystalline order reduces the affinity of the liquid. Using\na lattice model of a liquid, we show that this quantity successfully predicts\nthe tendency of a liquid to either accumulate or suppress local crystalline\nfluctuations with increasing supercooling. We demonstrate that the crystal\naffinity correlates strongly with the crystal nucleation rate and the\ncrystal-liquid interfacial free energy of the low-temperature liquid, making\nour theory a predictive tool to determine easily which amorphous structures\nenhance glass-forming ability."
    },
    {
        "anchor": "Adaptive two capacitor model to describe slide electrification in moving\n  water drops: Slide electrification is a spontaneous charge separation between a surface\nand a sliding drop. Here, we describe this effect in terms of a voltage\ngenerated at the three-phase contact line. This voltage moves charges between\ncapacitors, one formed by the drop and one on the surface. By introducing an\nadaptation of the voltage upon water contact, we can model drop charge\nexperiments on many surfaces, including more exotic ones with drop-rate\ndependent charge polarity. Thus, the adaptive two capacitor model enables new\ninsights into the molecular details of the charge separation mechanism.",
        "positive": "Enhanced motility in a binary mixture of active nano/microswimmers: It is often desirable to enhance the motility of active nano- or microscale\nswimmers such as, e.g., self-propelled Janus particles as agents of chemical\nreactions or weak sperm cells for better chances of successful fertilization.\nHere we tackle this problem based on the idea that motility can be transferred\nfrom a more active guest species to a less active host species. We performed\nnumerical simulations of motility transfer in two typical cases, namely for\ninteracting particles with weak inertia effect, by analyzing their velocity\ndistributions, and for interacting overdamped particles, by studying their\neffusion rate. In both cases we detected motility transfer with a motility\nenhancement of the host species of up to a factor of four. This technique of\nmotility enhancement can find applications in chemistry, biology and medicine."
    },
    {
        "anchor": "Tunable viscosity modification with diluted particles: When particles\n  decrease the viscosity of complex fluids: While spherical particles are the most studied viscosity modifiers, they are\nwell known only to increase viscosities, in particular at low concentrations.\nExtended studies and theories on non-spherical particles find a more\ncomplicated behavior, but still a steady increase. Involving platelets in\ncombination with complex fluids displays an even more complex scenario that we\nanalyze experimentally and theoretically as a function of platelet diameter, to\nfind the underlying concepts. Using a broad toolbox of different techniques we\nwere able to decrease the viscosity of crude oils although solid particles were\nadded. This apparent contradiction could lead to a wider range of applications.",
        "positive": "Controlling the microstructure and phase behavior of confined soft\n  colloids by active interaction switching: We explore the microstructure and phase behavior of confined soft colloids\nwhich can actively switch their interactions at a predefined kinetic rate. For\nthis, we employ a reaction-diffusion approach based on a reactive dynamical\ndensity-functional theory (R-DDFT) and study the effect of a binary (two-state)\nswitching of the size of colloids interacting with a Gaussian pair potential.\nThe rate of switching interpolates between a near-equilibrium binary Gaussian\nmixture at low rates and an effective monodisperse liquid for large rates,\nhence strongly affecting the one-body density profiles, adsorption, and\npressure at confining walls. Importantly, we demonstrate that sufficiently fast\nswitching impedes the phase separation of an (in equilibrium) unstable liquid,\nallowing the dynamic control of the degree of mixing/condensation and local\nmicro-structuring in a cellular confinement by tuning the switching rate."
    },
    {
        "anchor": "Topology of desiccation crack patterns in clay and invariance of crack\n  interface area with thickness: We study the crack patterns developed on desiccating films of an aqueous\ncolloidal suspension of bentonite on a glass substrate. Varying the thickness\nof the layer $h$ gives the following new and interesting results: (i)We\nidentify a critical thickness $h_{c}$, above which isolated cracks join each\nother to form a fully connected network. A topological analysis of the crack\nnetwork shows that the Euler number falls to a minimum at $h_{c}$. (ii) We find\nfurther, that the total vertical surface area of the clay $A_v$, which has\nopened up due to cracking, is a constant independent of the layer thickness for\n$h \\geq h_c$. (iii) The total area of the glass substrate $A_s$, exposed by the\nhierarchical sequence of cracks is also a constant for $h \\geq h_c$. These\nresults are shown to be consistent with a simple energy conservation argument,\nneglecting dissipative losses. (iv) Finally we show that if the crack pattern\nis viewed at successively finer resolution, the total cumulative area of cracks\nvisible at a certain resolution, scales with the layer thickness. A suspension\nof Laponite in methanol is found to exhibit similar salient features (i)-(iv),\nthough in this case the crack initiation process for very thin layers is quite\ndifferent.",
        "positive": "Spatio-temporal dynamics of an active, polar, viscoelastic ring: Constitutive equations for a one-dimensional, active, polar, viscoelastic\nliquid are derived by treating the strain field as a slow hydrodynamic\nvariable. Taking into account the couplings between strain and polarity allowed\nby symmetry, the hydrodynamics of an active, polar, viscoelastic body include\nan evolution equation for the polarity field that generalizes the damped\nKuramoto-Sivashinsky equation. Beyond thresholds of the active coupling\ncoefficients between the polarity and the stress or the strain rate,\nbifurcations of the homogeneous state lead first to stationary waves, then to\npropagating waves of the strain, stress and polarity fields. I argue that these\nresults are relevant to living matter, and may explain rotating actomyosin\nrings in cells and mechanical waves in epithelial cell monolayers."
    },
    {
        "anchor": "Topology-driven ordering of flocking matter: When interacting motile units self-organize into flocks, they realize one of\nthe most robust ordered state found in nature. However, after twenty five years\nof intense research, the very mechanism controlling the ordering dynamics of\nboth living and artificial flocks has remained unsettled. Here, combining\nactive-colloid experiments, numerical simulations and analytical work, we\nexplain how flocking liquids heal their spontaneous flows initially plagued by\ncollections of topological defects to achieve long-ranged polar order even in\ntwo dimensions. We demonstrate that the self-similar ordering of flocking\nmatter is ruled by a living network of domain walls linking all $\\pm 1$\nvortices, and guiding their annihilation dynamics. Crucially, this singular\norientational structure echoes the formation of extended density patterns in\nthe shape of interconnected bow ties. We establish that this double structure\nemerges from the interplay between self-advection and density gradients\ndressing each $-1$ topological charges with four orientation walls. We then\nexplain how active Magnus forces link all topological charges with extended\ndomain walls, while elastic interactions drive their attraction along the\nresulting filamentous network of polarization singularities. Taken together our\nexperimental, numerical and analytical results illuminate the suppression of\nall flow singularities, and the emergence of pristine unidirectional order in\nflocking matter.",
        "positive": "Computing the elastic mechanical properties of rod-like DNA\n  nanostructures: To study the elastic properties of rod-like DNA nanostructures, we perform\nlong simulations of these structure using the oxDNA coarse-grained model. By\nanalysing the fluctuations in these trajectories we obtain estimates of the\nbend and twist persistence lengths, and the underlying bend and twist elastic\nmoduli and couplings between them. Only on length scales beyond those\nassociated with the spacings between the interhelix crossovers do the bending\nfluctuations behave like those of a worm-like chain. The obtained bending\npersistence lengths are much larger than that for double-stranded DNA and\nincrease non-linearly with the number of helices, whereas the twist moduli\nincrease approximately linearly. To within the numerical error in our data, the\ntwist-bend coupling constants are of order zero. That the bending persistence\nlengths we obtain are generally somewhat higher than in experiment probably\nreflects both that the simulated origami have no assembly defects and that the\noxDNA extensional modulus for double-stranded DNA is too large."
    },
    {
        "anchor": "The repton model of gel electrophoresis: We discuss the repton model of agarose gel electrophoresis of DNA. We review\nprevious results, both analytic and numerical, as well as presenting a new\nnumerical algorithm for the efficient simulation of the model, and suggesting a\nnew approach to the model's analytic solution.",
        "positive": "Transient Pattern Formation in an Active Matter Contact Poisoning Model: One of the most notable features in repulsive particle based active matter\nsystems is motility-induced-phase separation (MIPS) where a dense, often\ncrystalline phase coexists with a low density fluid. In most active matter\nstudies, the activity is kept constant as a function of time; however, there\nare many examples of active systems in which individual particles transition\nfrom living or moving to dead or nonmotile due to lack of fuel, infection, or\npoisoning. Here we consider an active matter particle system at densities where\nMIPS does not occur. When we add a small number of infected particles that can\neffectively poison other particles, rendering them nonmotile, we find a rich\nvariety of time dependent pattern formation, including MIPS, a wetting phase,\nand a fragmented state formed when mobile particles plow through an nonmotile\npacking. We map out the patterns as a function of time scaled by the duration\nof the epidemic, and show that the pattern formation is robust for a wide range\nof poisoning rates and activity levels. We also show that pattern formation\ndoes not occur in a random death model, but requires the promotion of\nnucleation by contact poisoning. Our results should be relevant to biological\nand active matter systems where there is some form of poisoning, death, or\ntransition to nonmotility."
    },
    {
        "anchor": "Effect of reorientation statistics on torque response of self propelled\n  particles: We consider the dynamics of self-propelled particles subject to external\ntorques. Two models for the reorientation of self-propulsion are considered,\nrun-and-tumble particles, and active Brownian particles. Using the standard\ntools of non-equilibrium statistical mechanics we show that the run and tumble\nparticles have a more robust response to torques. This macroscopic signature of\nthe underlying reorientation statistics can be used to differentiate between\nthe two types of self propelled particles. Further this result might indicate\nthat run and tumble motion is indeed the evolutionarily stable dynamics for\nbacteria.",
        "positive": "Density profiles of loose and collapsed cohesive granular structures\n  generated by ballistic deposition: Loose granular structures stabilized against gravity by an effective cohesive\nforce are investigated on a microscopic basis using contact dynamics. We study\nthe influence of the granular Bond number on the density profiles and the\ngeneration process of packings, generated by ballistic deposition under\ngravity. The internal compaction occurs discontinuously in small avalanches and\nwe study their size distribution. We also develop a model explaining the final\ndensity profiles based on insight about the collapse of a packing under changes\nof the Bond number."
    },
    {
        "anchor": "Inhomogeneous relaxation in vibrated granular media: consolidation waves: We investigate the spatial dependence of the density of vibrated granular\nbeds, using simulations based on a hybrid Monte Carlo algorithm. We find that\nthe initial consolidation is typically inhmogeneous, both in the presence of a\nconstant shaking intensity and when the granular bed is submitted to `annealed\nshaking'. We also present a theoretical model which explains such inhomogeneous\nrelaxation in terms of a `consolidation wave', in good qualitative agreement\nwith our simulations. Our results are also in qualitative agreement with recent\nsimulations.",
        "positive": "Active ideal sedimentation: Exact two-dimensional steady states: We consider an ideal gas of active Brownian particles that undergo\nself-propelled motion and both translational and rotational diffusion under the\ninfluence of gravity. We solve analytically the corresponding Smoluchowski\nequation in two space dimensions for steady states. The resulting one-body\ndensity is given as a series, where each term is a product of an\norientation-dependent Mathieu function and a height-dependent exponential. A\nlower hard wall is implemented as a no-flux boundary condition. Numerical\nevaluation of the suitably truncated analytical solution shows the formation of\ntwo different spatial regimes upon increasing Peclet number. These regimes\ndiffer in their mean particle orientation and in their variation of the\norientation-averaged density with height."
    },
    {
        "anchor": "Demonstration and interpretation of \"scutoid\" cells in a quasi-2D soap\n  froth: Recently a novel type of epithelial cell has been discovered and dubbed the\n\"scutoid\". It is induced by curvature of the bounding surfaces. We show by\nsimulations and experiments that such cells are to be found in a dry foam\nsubjected to this boundary condition.",
        "positive": "Quantized Roentgen Effect in Bose-Einstein Condensates: A classical dielectric moving in a charged capacitor can create a magnetic\nfield (Roentgen effect). A quantum dielectric, however, will not produce a\nmagnetization, except at vortices. The magnetic field outside the quantum\ndielectric appears as the field of quantized monopoles."
    },
    {
        "anchor": "Defect-Mediated Emulsification in Two Dimensions: We consider two dimensional dispersions of droplets of isotropic phase in a\nliquid with an XY-like order parameter, tilt, nematic, and hexatic symmetries\nbeing included. Strong anchoring boundary conditions are assumed. Textures for\na single droplet and a pair of droplets are calculated and a universal\ndroplet-droplet pair potential is obtained. The interaction of dispersed\ndroplets via the ordered phase is attractive at large distances and repulsive\nat short distances, which results in a well defined preferred separation for\ntwo droplets and topological stabilization of the emulsion. This interaction\nalso drives self-assembly into chains. Preferred separations and energy\nbarriers to coalescence are calculated, and effects of thermal fluctuations and\nfilm thickness are discussed.",
        "positive": "A multi-species exchange model for fully fluctuating polymer field\n  theory simulations: Field-theoretic models have been used extensively to study the phase behavior\nof inhomogeneous polymer melts and solutions, both in self-consistent\nmean-field calculations and in numerical simulations of the full theory\ncapturing composition fluctuations. The models commonly used can be grouped\ninto two categories, namely {\\it species} models and {\\it exchange} models.\nSpecies models involve integrations of functionals that explicitly depend on\nfields originating both from species density operators and their conjugate\nchemical potential fields. In contrast, exchange models retain only linear\ncombinations of the chemical potential fields. In the two-component case,\ndevelopment of exchange models has been instrumental in enabling stable complex\nLangevin (CL) simulations of the full complex-valued theory. No comparable\nstable CL approach has yet been established for field theories of the species\ntype. Here we introduce an extension of the exchange model to an arbitrary\nnumber of components, namely the multi-species exchange (MSE) model, which\ngreatly expands the classes of soft material systems that can accessed by the\ncomplex Langevin simulation technique. We demonstrate the stability and\naccuracy of the MSE-CL sampling approach using numerical simulations of\ntriblock and tetrablock terpolymer melts, and tetrablock quaterpolymer melts.\nThis method should enable studies of a wide range of fluctuation phenomena in\nmultiblock/multi-species polymer blends and composites."
    },
    {
        "anchor": "Bidirectional Zigzag Growth from Clusters of Active Colloidal Shakers: Driven or self-propelling particles moving in viscoelastic fluids recently\nemerge as novel class of active systems showing a complex yet rich set of\nphenomena due to the non-Newtonian nature of the dispersing medium. Here we\ninvestigate the one-dimensional growth of clusters made of active colloidal\nshakers, which are realized by oscillating magnetic rotors dispersed within a\nviscoelastic fluid and at different concentration of the dissolved polymer.\nThese magnetic particles when actuated by an oscillating field display a flow\nprofile similar to that of a shaker force dipole, i.e. without any net\npropulsion. We design a protocol to assemble clusters of colloidal shakers and\ninduce their controlled expansion into elongated zigzag structures. We observe\na power law growth of the mean chain length and use theoretical arguments to\nexplain the measured $1/3$ exponent. These arguments agree well with both\nexperiments and particle based numerical simulations.",
        "positive": "Hydrodynamics of self-propelled hard rods: Motivated by recent simulations and by experiments on aggregation of gliding\nbacteria, we study a model of the collective dynamics of self-propelled hard\nrods on a substrate in two dimensions. The rods have finite size, interact via\nexcluded volume and their dynamics is overdamped by the interaction with the\nsubstrate. Starting from a microscopic model with non-thermal noise sources, a\ncontinuum description of the system is derived. The hydrodynamic equations are\nthen used to characterize the possible steady states of the systems and their\nstability as a function of the particles packing fraction and the speed of self\npropulsion."
    },
    {
        "anchor": "Surface Fluctuating Hydrodynamics Methods for the Drift-Diffusion\n  Dynamics of Particles and Microstructures within Curved Fluid Interfaces: We introduce fluctuating hydrodynamics approaches on surfaces for capturing\nthe drift-diffusion dynamics of particles and microstructures immersed within\ncurved fluid interfaces of spherical shape. We take into account the\ninterfacial hydrodynamic coupling, traction coupling with the surrounding bulk\nfluid, and thermal fluctuations. For fluid-structure interactions, we introduce\nImmersed Boundary Methods (IBM) and related Stochastic Eulerian-Lagrangian\nMethods (SELM) for curved surfaces. We use these approaches to investigate the\nstatistics of surface fluctuating hydrodynamics and microstructures. For\nvelocity autocorrelations, we find characteristic power-law scalings\n$\\tau^{-1}$, $\\tau^{-2}$, and plateaus can emerge. This depends on the physical\nregime associated with the geometry, surface viscosity, and bulk viscosity.\nThis differs from the characteristic $\\tau^{-3/2}$ scaling for bulk three\ndimensional fluids. We develop theory explaining these observed power-laws\nassociated with time-scales for dissipation within the fluid interface and\ncoupling to the surrounding fluid. We then use our introduced methods to\ninvestigate a few example systems and roles of hydrodynamic coupling and\nthermal fluctuations including for the kinetics of passive particles and active\nmicroswimmers in curved fluid interfaces.",
        "positive": "On the dependence of the leak-rate of seals on the skewness of the\n  surface height probability distribution: Seals are extremely useful devices to prevent fluid leakage. We present\nexperimental result which show that the leak-rate of seals depend sensitively\non the skewness in the height probability distribution. The experimental data\nare analyzed using the critical-junction theory. We show that using the\ntop-power spectrum result in good agreement between theory and experiment."
    },
    {
        "anchor": "Electronic pathway in the photosynthetic reaction centers and some\n  mutation of RC's: The reaction center of Chloroflexus aurantiacus and Rhodobacter sphaeroides\nmutation of RC`s was investigated. To describe the kinetic of the Chloroflexus\naurantiacus RC's we use incoherent model of electron transfer. It was shown\nthat the asymmetry in electronic coupling must be included to explain the\nexperiments. For the description of Rhodobacter sphaeroides H(M182)L mutation\nwe used partially coherent as incoherent models of electron transfer. These two\nmodels are discussed with regard to the observed electron transfer kinetics. It\ncan be concluded that partially coherent model is more adequate. We predict\nsome new electron pathways for describing the kinetic of RC's and some\nmutation.",
        "positive": "Self-consistent field theoretic simulations of amphiphilic triblock\n  copolymer solutions: Polymer concentration and chain length effects: Using the self-consistent field lattice model, polymer concentration\n$\\bar{\\phi}_{{P}}$ and chain length $N$ (keeping the length ratio of\nhydrophobic to hydrophilic blocks constant) the effects on\ntemperature-dependent behavior of micelles are studied, in amphiphilic\nsymmetric ABA triblock copolymer solutions. When chain length is increased, at\nfixed $\\bar{\\phi}_{{P}}$, micelles occur at higher temperature. The variations\nof average volume fraction of stickers $\\bar{\\phi}_\\textrm{co}^\\textrm{s}$ and\nthe lattice site numbers $N_\\textrm{co}^\\textrm{ls}$ at the micellar cores with\ntemperature are dependent on $N$ and $\\bar{\\phi}_{{P}}$, which demonstrates\nthat the aggregation of micelles depends on $N$ and $\\bar{\\phi}_{{P}}$.\nMoreover, when $\\bar{\\phi}_{{P}}$ is increased, firstly a peak appears on the\ncurve of specific heat $C_V$ for unimer-micelle transition, and then in\naddition a primary peak, the secondary peak, which results from the\nremicellization, is observed on the curve of $C_V$. For a long chain, in\nintermediate and high concentration regimes, the shape of specific heat peak\nmarkedly changes, and the peak tends to be a more broad peak. Finally, the\naggregation behavior of micelles is explained by the aggregation way of\namphiphilic triblock copolymer. The obtained results are helpful in\nunderstanding the micellar aggregation process."
    },
    {
        "anchor": "Equilibrium properties of charged microgels: a Poisson-Boltzmann-Flory\n  approach: The equilibrium properties of ionic microgels are investigated using a\ncombination of the Poisson-Boltzmann and Flory theories. Swelling behavior,\ndensity profiles, and effective charges are all calculated in a self-consistent\nway. Special attention is given to the effects of salinity on these quantities.\nIt is found that the equilibrium microgel size is strongly influenced by the\namount of added salt. Increasing the salt concentration leads to a considerable\nreduction of the microgel volume, which therefore releases its internal\nmaterial -- solvent molecules and dissociated ions -- into the solution.\nFinally, the question of charge renormalization of ionic microgels in the\ncontext of the cell model is briefly addressed.",
        "positive": "Quasi-one-dimensional disordered systems: fluctuations, transport and\n  interplay: In a one dimensional lattice thermal fluctuations destroy the long-range\norder making particles of the lattice move on a scale much larger than the\nlattice spacing. We discuss the assumption that this motion may be responsible\nfor the transport of localized electrons in a system of weakly coupled chains.\nThe model with diffusing localization sites gives a temperature-independent\nmobility with a crossover to an activated dependence at high temperature. This\nprediction is consistent with and might account for experimental results on\ndiscotic liquid crystals and certain biopolymers."
    },
    {
        "anchor": "Droplet and cluster formation in freely falling granular streams: Particle beams are important tools for probing atomic and molecular\ninteractions. Here we demonstrate that particle beams also offer a unique\nopportunity to investigate interactions in macroscopic systems, such as\ngranular media. Motivated by recent experiments on streams of grains that\nexhibit liquid-like breakup into droplets, we use molecular dynamics\nsimulations to investigate the evolution of a dense stream of macroscopic\nspheres accelerating out of an opening at the bottom of a reservoir. We show\nhow nanoscale details associated with energy dissipation during collisions\nmodify the stream's macroscopic behavior. We find that inelastic collisions\ncollimate the stream, while the presence of short-range attractive interactions\ndrives structure formation. Parameterizing the collision dynamics by the\ncoefficient of restitution (i.e., the ratio of relative velocities before and\nafter impact) and the strength of the cohesive interaction, we map out a\nspectrum of behaviors that ranges from gas-like jets in which all grains drift\napart to liquid-like streams that break into large droplets containing hundreds\nof grains. We also find a new, intermediate regime in which small aggregates\nform by capture from the gas phase, similar to what can be observed in\nmolecular beams. Our results show that nearly all aspects of stream behavior\nare closely related to the velocity gradient associated with vertical free\nfall. Led by this observation, we propose a simple energy balance model to\nexplain the droplet formation process. The qualitative as well as many\nquantitative features of the simulations and the model compare well with\navailable experimental data and provide a first quantitative measure of the\nrole of attractions in freely cooling granular streams.",
        "positive": "On the geometric phenomenology of static friction: In this note we introduce a hierarchy of phase spaces for static friction,\nwhich give a graphical way to systematically quantify the directional\ndependence in static friction via subregions of the phase spaces. We\nexperimentally plot these subregions to obtain phenomenological descriptions\nfor static friction in various examples where the macroscopic shape of the\nobject affects the frictional response. The phase spaces have the universal\nproperty that for any experiment in which a given object is put on a substrate\nfashioned from a chosen material with a specified nature of contact,the\nfrictional behavior can be read off from a uniquely determined classifying map\non the control space of the experiment which takes values in the appropriate\nphase space."
    },
    {
        "anchor": "Solid-solid collapse transition in a two dimensional model molecular\n  system: Solid-solid collapse transition in open framework structures is ubiquitous in\nnature. The real difficulty in understanding detailed microscopic aspects of\nsuch transitions in molecular systems arises from the interplay between\ndifferent energy and length scales involved in molecular systems, often\nmediated through a solvent. In this work we employ Monte Carlo (MC) simulations\nto study the collapse transition in a model molecular system interacting via\nboth isotropic as well as anisotropic interactions having different length and\nenergy scales. The model we use is known as Mercedes-Benz (MB) which for a\nspecific set of parameters sustains three solid phases: honeycomb, oblique and\ntriangular. In order to study the temperature induced collapse transition, we\nstart with a metastable honeycomb solid and induce transition by heating. High\ndensity oblique solid so formed has two characteristic length scales\ncorresponding to isotropic and anisotropic parts of interaction potential.\nContrary to the common believe and classical nucleation theory, interestingly,\nwe find linear strip-like nucleating clusters having significantly different\norder and average coordination number than the bulk stable phase. In the early\nstage of growth, the cluster grows as linear strip followed by branched and\nring-like strips. The geometry of growing cluster is a consequence of the\ndelicate balance between two types of interactions which enables the dominance\nof stabilizing energy over the destabilizing surface energy. The nuclei of\nstable oblique phase are wetted by intermediate order particles which minimizes\nthe surface free energy. We observe different pathways for pressure and\ntemperature induced transitions.",
        "positive": "Semi-soft Nematic Elastomers and Nematics in Crossed Electric and\n  Magnetic Fields: Nematic elastomers with a locked-in anisotropy direction exhibit semi-soft\nelastic response characterized by a plateau in the stress-strain curve in which\nstress does not change with strain. We calculate the global phase diagram for a\nminimal model, which is equivalent to one describing a nematic in crossed\nelectric and magnetic fields, and show that semi-soft behavior is associated\nwith a broken symmetry biaxial phase and that it persists well into the\nsupercritical regime. We also consider generalizations beyond the minimal model\nand find similar results."
    },
    {
        "anchor": "Intramolecular Form Factor in Dense Polymer Systems: Systematic\n  Deviations from the Debye formula: We discuss theoretically and numerically the intramolecular form factor\n$F(q)$ in dense polymer systems. Following Flory's ideality hypothesis, chains\nin the melt adopt Gaussian configurations and their form factor is supposed to\nbe given by Debye's formula. At striking variance to this, we obtain noticeable\n(up to 20%) non-monotonic deviations which can be traced back to the\nincompressibility of dense polymer solutions beyond a local scale. The Kratky\nplot ($q^2F(q)$ {\\it vs.} wavevector $q$) does not exhibit the plateau expected\nfor Gaussian chains in the intermediate $q$-range. One rather finds a\nsignificant decrease according to the correction $\\delta(F^{-1}(q)) =\nq^3/32\\rho$ that only depends on the concentration $\\rho$ of the solution, but\nneither on the persistence length or the interaction strength.",
        "positive": "Phase behavior of repulsive polymer-tethered colloids: We report molecular dynamics simulations of a system of repulsive,\npolymer-tethered colloidal particles. We use an explicit polymer model to\nexplore how the length and the behavior of the polymer (ideal or self-avoiding)\naffect the ability of the particles to organize into ordered structures when\nthe system is compressed to moderate volume fractions. We find a variety of\ndifferent phases whose origin can be explained in terms of the configurational\nentropy of polymers and colloids. Finally, we discuss and compare our results\nto those obtained for similar systems using simplified coarse-grained polymer\nmodels, and set the limits of their applicability."
    },
    {
        "anchor": "Particle dynamics in two-dimensional random energy landscapes -\n  experiments and simulations: The dynamics of individual colloidal particles in random potential energy\nlandscapes were investigated experimentally and by Monte Carlo simulations. The\nvalue of the potential at each point in the two-dimensional energy landscape\nfollows a Gaussian distribution. The width of the distribution, and hence the\ndegree of roughness of the energy landscape, was varied and its effect on the\nparticle dynamics studied. This situation represents an example of Brownian\ndynamics in the presence of disorder. In the experiments, the energy landscapes\nwere generated optically using a holographic set-up with a spatial light\nmodulator, and the particle trajectories were followed by video microscopy. The\ndynamics are characterized using, e.g., the time-dependent diffusion\ncoefficient, the mean squared displacement, the van Hove function and the\nnon-Gaussian parameter. In both, experiments and simulations, the dynamics are\ninitially diffusive, show an extended sub-diffusive regime at intermediate\ntimes before diffusive motion is recovered at very long times. The dependence\nof the long-time diffusion coefficient on the width of the Gaussian\ndistribution agrees with theoretical predictions. Compared to the dynamics in a\none-dimensional potential energy landscape, the localization at intermediate\ntimes is weaker and the diffusive regime at long times reached earlier, which\nis due to the possibility to avoid local maxima in two-dimensional energy\nlandscapes.",
        "positive": "Active colloids in the context of chemical kinetics: We study a mesoscopic model of a chemically active colloidal particle which\non certain parts of its surface promotes chemical reactions in the surrounding\nsolution. For reasons of simplicity and conceptual clarity, we focus on the\ncase in which only electrically neutral species are present in the solution and\non chemical reactions which are described by first order kinetics. Within a\nself-consistent approach we explicitly determine the steady state product and\nreactant number density fields around the colloid as functionals of the\ninteraction potentials of the various molecular species in solution with the\ncolloid. By using Teubner's reciprocal theorem, this allows us to compute and\nto interpret -- in a transparent way in terms of the classical Smoluchowski\ntheory of chemical kinetics -- the external force needed to keep such a\ncatalytically active colloid at rest (\\textit{stall} force) or, equivalently,\nthe corresponding velocity of the colloid \\textit{if} it is free to move. We\nuse the particular case of triangular-well interaction potentials as a\nbenchmark example for applying the general theoretical framework developed\nhere. For this latter case, we derive explicit expressions for the dependences\nof the quantities of interest on the diffusion coefficients of the chemical\nspecies, the reaction rate constant, the coverage by catalyst, the size of the\ncolloid, as well as on the parameters of the interaction potentials. These\nexpressions provide a detailed picture of the phenomenology associated with\ncatalytically-active colloids and self-diffusiophoresis."
    },
    {
        "anchor": "Elastocapillary Snapping: Capillarity Induces Snap-Through Instabilities\n  in Small Elastic Beams: We report on the capillary-induced snapping of elastic beams. We show that a\nmillimeter-sized water drop gently deposited on a thin buckled polymer strip\nmay trigger an elastocapillary snap-through instability. We investigate\nexperimentally and theoretically the statics and dynamics of this phenomenon\nand we further demonstrate that snapping can act against gravity, or be induced\nby soap bubbles on centimeter-sized thin metal strips. We argue that this\nphenomenon is suitable to miniaturization and design a condensation-induced\nspin-off version of the experiment involving an hydrophilic strip placed in a\nsteam flow.",
        "positive": "Coarse Graining of Nonbonded Inter-particle Potentials Using Automatic\n  Simplex Optimization to Fit Structural Properties: We implemented a coarse-graining procedure to construct mesoscopic models of\ncomplex molecules. The final aim is to obtain better results on properties\ndepending on slow modes of the molecules. Therefore the number of particles\nconsidered in molecular dynamics simulations is reduced while conserving as\nmany properties of the original substance as possible. We address the problem\nof finding nonbonded interaction parameters which reproduce structural\nproperties from experiment or atomistic simulations. The approach consists of\noptimizing automatically nonbonded parameters using the simplex algorithm to\nfit structural properties like the radial distribution function as target\nfunctions. Moreover, any mix of structural and thermodynamic properties can be\nincluded in the target function. Different spherically symmetric inter-particle\npotentials are discussed. Besides demonstrating the method for Lennard--Jones\nliquids, it is applied to several more complex molecular liquids such as\ndiphenyl carbonate, tetrahydrofurane, and monomers of poly(isoprene)."
    },
    {
        "anchor": "Turbulence lifetimes: what we can learn from the physics of glasses: In this note, we critically discuss the issue of the possible finiteness of\nthe turbulence lifetime in subcritical transition to turbulence in shear flows,\nwhich attracted a lot of interest recently. We briefly review recent\nexperimental and numerical results, as well as theoretical proposals, and\ncompare the difficulties arising in assessing this issue in subcritical shear\nflow with that encountered in the study of the glass transition. In order to go\nbeyond the purely methodological similarities, we further elaborate on this\nanalogy and propose a qualitative mapping between these two apparently\nunrelated situations, which could possibly foster new directions of research in\nsubcritical shear flows.",
        "positive": "Anomalous behavior and structure of a liquid of particles interacting\n  through the harmonic-repulsive pair potential near the crystallization\n  transition: A characteristic property of many soft matter systems is an ultrasoft\neffective interaction between their structural units. This softness often leads\nto complex behavior. In particular, ultrasoft systems under pressure\ndemonstrate polymorphism of complex crystal and quasicrystal structures.\nTherefore, it is of interest to investigate how different can be the structure\nof the fluid state in such systems at different pressures. Here we address this\nissue for the model liquid composed of particles interacting through the\nharmonic-repulsive pair potential. This system can form different crystal\nstructures as the liquid is cooled. We find that, at certain pressures, the\nliquid exhibits unusual properties, such as the negative thermal expansion\ncoefficient. Besides, the volume and the potential energy of the system can\nincrease during crystallization. At certain pressures, the system demonstrates\nhigh stability against crystallization and it is hardly possible to crystallize\nit on the timescales of the simulations. To address the liquid's structure at\nhigh pressures, we consider the scaled pair distribution function (PDF) and the\nbond-orientational order (BOO) parameters. The marked change happening with the\nPDF, as pressure increases, is the splitting of the first peak which is caused\nby the appearance of non-negligible interaction with the second neighbors and\nthe following rearrangement of the structure. Our findings suggest that\nnon-trivial effects, usually explained by different interactions at different\nspatial scales, can be observed also in one-component systems with simple\none-length-scale ultrasoft repulsive interactions."
    },
    {
        "anchor": "On the relevance of numerical simulations to booming sand: We have performed a simulation study of 3D cohesionless granular flows down\nan inclined chute. We find that the oscillations observed in [L.E. Silbert,\nPhys. Rev. Lett., 94, 098002 (2005)] near the angle of repose are harmonic\nvibrations of the lowest normal mode. Their frequencies depend on the contact\nstiffness as well as on the depth of the flow. Could these oscillations account\nfor the phenomena of \"booming sand\"? We estimate an effective contact stiffness\nfrom the Hertz law, but this leads to frequencies several times higher than\nobserved. However, the Hertz law also predicts interpenetrations of a few\nnanometers, indicating that the oscillations frequencies are governed by the\nsurface stiffness, which can be much lower than the bulk one. This is in\nagreement with previous studies ascribing the ability to sing to the presence\nof a soft coating on the grain surface.",
        "positive": "Anomalous diffusion in an electrolyte saturated paper matrix: Diffusion of colored dye on water saturated paper substrates has been\ntraditionally exploited with great skill by renowned water color artists. The\nsame physics finds more recent practical applications in paper based diagnostic\ndevices deploying chemicals that react with a bodily fluid yielding\ncolorimetric signals for disease detection. During spontaneous imbibition\nthrough the tortuous pathways of a porous electrolyte saturated paper matrix, a\ndye molecule undergoes diffusion in a complex network of pores. The advancing\nfront forms a strongly correlated interface that propagates diffusively but\nwith an enhanced effective diffusivity. We measure this effective diffusivity\nand show that it is several orders of magnitude greater than the free solution\ndiffusivity and has a significant dependence on the solution pH and salt\nconcentration in the background electrolyte. We attribute this to electrically\nmediated interfacial interactions between the ionic species in the liquid dye\nand spontaneous surface charges developed at porous interfaces, and introduce a\nsimple theory to explain this phenomenon."
    },
    {
        "anchor": "Hydrodynamic Effects on Confined Polymers: We consider the statics and dynamics of a flexible polymer confined between\nparallel plates both in the presence and absence of hydrodynamic interactions.\nThe hydrodynamic interactions are described at the level of the fluctuating,\ncompressible Navier-Stokes equation. We consider two cases: (i) confinement for\nboth the solvent and the polymer, and (ii) confinement for the polymer only (in\na 3D solvent), which is experimentally feasible, for instance, by (optical)\ntrapping. We find a continuous transition from 2D to 3D dynamic scaling as a\nfunction of decreasing degree of confinement within the de Gennes and the\nweak-confinement regimes. We demonstrate that, in the presence of\nhydrodynamics, the polymer's center-of-mass diffusion coefficient in the\ndirection parallel to the walls scales differently as a function of the level\nof confinement in cases (i) and (ii). We also find that in the commonly used\nLangevin dynamics description, the polymer swells more parallel to the walls\nthan in the presence of hydrodynamics, and the planar diffusion coefficient\nshows scaling behavior similar to case (ii) rather than case (i). In addition,\nwe quantify the differences in the static structure factor of the polymer\nbetween cases (i) and (ii), and between case (i) and Langevin dynamics.",
        "positive": "Multidimensional optical fractionation with holographic verification: The trajectories of colloidal particles driven through a periodic potential\nenergy landscape can become kinetically locked in to directions dictated by the\nlandscape's symmetries. When the landscape is realized with forces exerted by a\nstructured light field, the path a given particle follows has been predicted to\ndepend exquisitely sensitively on such properties as the particle's size and\nrefractive index These predictions, however, have not been tested\nexperimentally. Here, we describe measurements of colloidal silica spheres'\ntransport through arrays of holographic optical traps that use holographic\nvideo microscopy to track individual spheres' motions in three dimensions and\nsimultaneously to measure each sphere's radius and refractive index with\npart-per-thousand resolution. These measurements confirm previously untested\npredictions for the threshold of kinetically locked-in transport, and\ndemonstrate the ability of optical fractionation to sort colloidal spheres with\npart-per-thousand resolution on multiple characteristics simultaneously."
    },
    {
        "anchor": "Thermally Increasing Correlation/Modulation Lengths and Other Selection\n  Rules in Systems with Long Range Interactions: In this article, addressing large $n$ systems, we report that in numerous\nsystems hosting long and short range interactions, multiple correlation lengths\nmay appear. The largest correlation lengths often monotonically increase with\ntemperature and diverge in the high temperature limit. Notwithstanding, the\nmagnitude of the correlations themselves decreases with increasing temperature.\nWe examine correlation function in the presence of competing interactions of\nlong and short ranges. The behavior of the correlation and modulation lengths\nas a function of temperature provides us with selection rules on the possible\nunderlying microscopic interactions. As a concrete example of these notions, we\nconsider the correlations in a system of screened Coulomb interactions\ncoexisting with attractive short range interactions.",
        "positive": "Precise Determination of Pair Interactions from Pair Statistics of\n  Many-Body Systems In and Out of Equilibrium: The determination of the pair potential $v({\\bf r})$ that accurately yields\nan equilibrium state at positive temperature $T$ with a prescribed pair\ncorrelation function $g_2({\\bf r})$ or corresponding structure factor $S({\\bf\nk})$ in $d$-dimensional Euclidean space $\\mathbb{R}^d$ is an outstanding\ninverse statistical mechanics problem with far-reaching implications. Recently,\nZhang and Torquato conjectured that any realizable $g_2({\\bf r})$ or $S({\\bf\nk})$ corresponding to a translationally invariant nonequilibrium system can be\nattained by a classical equilibrium ensemble involving only (up to) effective\npair interactions. Testing this conjecture for nonequilibrium systems as well\nas for nontrivial equilibrium states requires improved inverse methodologies.\nWe have devised a novel optimization algorithm to find effective pair\npotentials that correspond to pair statistics of general translationally\ninvariant disordered many-body equilibrium or nonequilibrium systems at\npositive temperatures. This methodology utilizes a parameterized family of\npointwise basis functions for the potential function whose initial form is\ninformed by small- and large-distance behaviors dictated by\nstatistical-mechanical theory. Subsequently, a nonlinear optimization technique\nis utilized to minimize an objective function that incorporates both the target\npair correlation function $g_2({\\bf r})$ and structure factor $S({\\bf k})$ so\nthat the small- and large-distance correlations are very accurately captured.\nTo illustrate the versatility and power of our methodology, we accurately\ndetermine the effective pair interactions of the following four diverse target\nsystems. We found that the optimized pair potentials generate corresponding\npair statistics that accurately match their corresponding targets with total\n$L_2$-norm errors that are an order of magnitude smaller than that of previous\nmethods."
    },
    {
        "anchor": "Inverse Optimization Techniques for Targeted Self-Assembly: This article reviews recent inverse statistical-mechanical methodologies that\nwe have devised to optimize interaction potentials in soft matter systems that\ncorrespond to stable \"target\" structures. We are interested in finding the\ninteraction potential, not necessarily pairwise additive or spherically\nsymmetric, that stabilizes a targeted many-body system by generally\nincorporating complete configurational information. Unlike previous work, our\nprimary interest is in the possible many-body structures that may be generated,\nsome of which may include interesting but known structures, while others may\nrepresent entirely new structural motifs. Soft matter systems, such as colloids\nand polymers, offer a versatile means of realizing the optimized interactions.\nIt is shown that these inverse approaches hold great promise for controlling\nself-assembly to a degree that surpasses the less-than-optimal path that nature\nhas provided. Indeed, we envision being able to \"tailor\" potentials that\nproduce varying degrees of disorder, thus extending the traditional idea of\nself-assembly to incorporate both amorphous and crystalline structures as well\nas quasicrystals. The notion of tailoring potentials that correspond to\ntargeted structures is motivated by the rich fundamental statistical-mechanical\nissues and questions offered by this fascinating inverse problem as well as our\nrecent ability to identify structures that have optimal bulk properties or\ndesirable performance characteristics. Recent results have already led to a\ndeeper basic understanding of the mathematical relationship between the\ncollective structural behavior of many-body systems and their interactions, as\nwell as optimized potentials that enable self-assembly of ordered and\ndisordered particle configurations with novel structural and bulk properties.",
        "positive": "Hydrodynamic Interactions of Self-Propelled Swimmers: The hydrodynamic interactions of a suspension of self-propelled particles are\nstudied using a direct numerical simulation method which simultaneously solves\nfor the host fluid and the swimming particles. A modified version of the\n\"Smoothed Profile\" method (SPM) is developed to simulate microswimmers as\nsquirmers, which are spherical particles with a specified surface-tangential\nslip velocity between the particles and the fluid. This simplified swimming\nmodel allows one to represent different types of propulsion (pullers and\npushers) and is thus ideal to study the hydrodynamic interactions among\nswimmers. We use the SPM to study the diffusive behavior which arises due to\nthe swimming motion of the particles, and show that there are two basic\nmechanisms responsible for this phenomena: the hydrodynamic interactions caused\nby the squirming motion of the particles, and the particle-particle collisions.\nThis dual nature gives rise to two distinct time- and length- scales, and thus\nto two diffusion coefficients, which we obtain by a suitable analysis of the\nswimming motion. We show that the collisions between swimmers can be\ninterpreted in terms of binary collisions, in which the effective collision\nradius is reduced due to the collision dynamics of swimming particles in\nviscous fluids. At short time-scales, the dynamics of the swimmer is analogous\nto that of an inert tracer particle in a swimming suspension, in which the\ndiffusive motion is caused by fluid-particle collisions. Our results, along\nwith the simulation method we have introduced, will allow us to gain a better\nunderstanding of the complex hydrodynamic interactions of self-propelled\nswimmers."
    },
    {
        "anchor": "Microscopic formulation of the Zimm-Bragg model for the helix-coil\n  transition: A microscopic spin model is proposed for the phenomenological Zimm-Bragg\nmodel for the helix-coil transition in biopolymers. This model is shown to\nprovide the same thermophysical properties of the original Zimm-Bragg model and\nit allows a very convenient framework to compute statistical quantities.\nPhysical origins of this spin model are made transparent by an exact mapping\ninto a one-dimensional Ising model with an external field. However, the\ndependence on temperature of the reduced external field turns out to differ\nfrom the standard one-dimensional Ising model and hence it gives rise to\ndifferent thermophysical properties, despite the exact mapping connecting them.\nWe discuss how this point has been frequently overlooked in the recent\nliterature.",
        "positive": "Temperature Expansions in the Square Shoulder Fluid II: Thermodynamics: In a companion paper, we derived analytical expressions for the structure\nfactor of the square-shoulder potential in a perturbative way around the high-\nand low-temperature regimes. Here, various physical properties of these\nsolutions are derived. In particular, we investigate the large wave number\nsector, and relate it to the contact values of the pair-correlation function.\nThen, thermoelastic properties of the square-shoulder fluids are discussed."
    },
    {
        "anchor": "Template Dissolution Interfacial Patterning of Single Colloids for\n  Nanoelectrochemistry and Nanosensing: Deterministic positioning and assembly of colloidal nanoparticles (NPs) onto\nsubstrates is a core requirement and a promising alternative to top down\nlithography to create functional nanostructures and nanodevices with intriguing\noptical, electrical, and catalytic features. Capillary-assisted particle\nassembly (CAPA) has emerged as an attractive technique to this end, as it\nallows controlled and selective assembly of a wide variety of NPs onto\npredefined topographical templates using capillary forces. One critical issue\nwith CAPA, however, lies in its final printing step, where high printing yields\nare possible only with the use of an adhesive polymer film. To address this\nproblem, we have developed a template dissolution interfacial patterning (TDIP)\ntechnique to assemble and print single colloidal AuNP arrays onto various\ndielectric and conductive substrates in the absence of any adhesion layer, with\nprinting yields higher than 98%. The TDIP approach grants direct access to the\ninterface between the AuNP and the target surface, enabling the use of\ncolloidal AuNPs as building blocks for practical applications. The versatile\napplicability of TDIP is demonstrated by the creation of direct electrical\njunctions for electro- and photoelectrochemistry and nanoparticle-on-mirror\ngeometries for single particle molecular sensing.",
        "positive": "Brownian Dynamics of Confined Suspensions of Active Microrollers: We develop efficient numerical methods for performing many-body Brownian\ndynamics simulations of a recently-observed fingering instability in an active\nsuspension of colloidal rollers sedimented above a wall [M. Driscoll, B.\nDelmotte, M. Youssef, S. Sacanna, A. Donev and P. Chaikin, Nature Physics,\n2016, doi:10.1038/nphys3970]. We present a stochastic Adams-Bashforth\nintegrator for the equations of Brownian dynamics, which has the same cost as\nbut is more accurate than the widely-used Euler-Maruyama scheme, and uses a\nrandom finite difference to capture the stochastic drift proportional to the\ndivergence of the configuration-dependent mobility matrix. We generate the\nBrownian increments using a Krylov method, and show that for particles confined\nto remain in the vicinity of a no-slip wall by gravity or active flows the\nnumber of iterations is independent of the number of particles. Our numerical\nexperiments with active rollers show that the thermal fluctuations set the\ncharacteristic height of the colloids above the wall, both in the initial\ncondition and the subsequent evolution dominated by active flows. The\ncharacteristic height in turn controls the timescale and wavelength for the\ndevelopment of the fingering instability."
    },
    {
        "anchor": "Shear Layers and Plugs in the Capillary Flow of Wormlike Micellar Gels: Wormlike micellar solutions formed by long-chained zwitterionic surfactants\nshow gel-like rheology at room temperature and have recently been found to\nexhibit other complex and interesting rheological features. We study the\ndynamics of these wormlike micellar gels in a pipe-flow scenario using optical\ncoherence tomography-based velocimetry and report the existence of plug flows\nwith strong wall slip and non-parabolic velocity profiles for different\nsurfactant concentrations and imposed flow rates. We rationalize these results\nas features of a developing transient flow of a viscoelastic solution in space\nand time and show that these shear layers indicate a flow induced\nheterogeneity. Our experiments shed light on the transient fluid dynamics of\nwormlike micelles in simple geometries and highlight the complexity of flows\ninvolving wormlike micellar gels and similar soft matter systems in canonical\nflows.",
        "positive": "Balancing torques in membrane-mediated interactions: Exact results and\n  numerical illustrations: Torques on interfaces can be described by a divergence-free tensor which is\nfully encoded in the geometry. This tensor consists of two terms, one\noriginating in the couple of the stress, the other capturing an intrinsic\ncontribution due to curvature. In analogy to the description of forces in terms\nof a stress tensor, the torque on a particle can be expressed as a line\nintegral along any contour surrounding the particle. Interactions between\nparticles mediated by a fluid membrane are studied within this framework. In\nparticular, torque balance places a strong constraint on the shape of the\nmembrane. Symmetric two-particle configurations admit simple analytical\nexpressions which are valid in the fully nonlinear regime; in particular, the\nproblem may be solved exactly in the case of two membrane-bound parallel\ncylinders. This apparently simple system provides some flavor of the remarkably\nsubtle nonlinear behavior associated with membrane-mediated interactions."
    },
    {
        "anchor": "Using Fundamental Measure Theory to Treat the Correlation Function of\n  the Inhomogeneous Hard-Sphere Fluid: We investigate the value of the correlation function of an inhomogeneous\nhard-sphere fluid at contact. This quantity plays a critical role in\nStatistical Associating Fluid Theory (SAFT), which is the basis of a number of\nrecently developed classical density functionals. We define two averaged values\nfor the correlation function at contact, and derive formulas for each of them\nfrom the White Bear version of the Fundamental Measure Theory functional, using\nan assumption of thermodynamic consistency. We test these formulas, as well as\ntwo existing formulas against Monte Carlo simulations, and find excellent\nagreement between the Monte Carlo data and one of our averaged correlation\nfunctions.",
        "positive": "Liquid crystals and their defects: These lecture notes discuss classical models of liquid crystals, and the\ndifferent ways in which defects are described according to the different\nmodels."
    },
    {
        "anchor": "A 3 - dimensionally modulated structure in a chiral smectic-C liquid\n  crystal: We report the discovery of a new Twist Grain Boundary phase. This phase is\ncharacterised by a 2-dimensional undulation of the smectic C* like blocks in\nthe form of a square lattice. We suggest that this three dimensionally\nmodulated structure, which was not anticipated by theory, owes its origin to\nchiral interactions.",
        "positive": "Effect of small-scale architecture on polymer mobility: Processes on different length scales affect the dynamics of chain molecules.\nIn this work, we focus on structures on the scale of a monomer and investigate\npolyolefins, i.e. hydrocarbon chains with different small scale architectures.\nWe present an exact enumeration scheme for the simulation of interactions and\nrelative motion of two short chain sections on a lattice and employ it to\ndeduce the probability for segmental motion for polymers of four different\narchitectures in the melt. The probability for segmental motion is inversely\nproportional to the monomeric friction coefficient and hence the viscosity of a\npolymer. Combining our simulation results with an equation of state for the\nthermodynamic properties of the polymers, we are able to make predictions about\nthe variation of the friction coefficient with temperature, pressure, and small\nscale architecture. To compare our results with experimental data, we have\ndetermined monomeric friction coefficients from experimental viscosity data for\nthe four polyolefins considered in this work. For temperatures well above the\nglass transition temperature, we find that our simple approach gives a good\nqualitative representation of the variation of the friction coefficient with\nchain architecture, temperature and pressure."
    },
    {
        "anchor": "Do active nematic self-mixing dynamics help growing bacterial colonies\n  to maintain local genetic diversity?: Recent studies have shown that packings of cells, both eukaryotic cellular\ntissues and growing or swarming bacterial colonies, can often be understood as\nactive nematic fluids. A key property of volume-conserving active nematic model\nsystems is chaotic self-mixing characterized by motile topological defects.\nHowever, for active nematics driven by growth rather than motility, less is\nunderstood about mixing and defect motion. Mixing could affect evolutionary\noutcomes in bacterial colonies by counteracting the tendency to spatially\nsegregate into monoclonal sectors, which reduces the local genetic diversity\nand confines competition between subpopulations to the boundaries between\nneighboring sectors. To examine whether growth-driven active nematic physics\ncould influence this genetic demixing process, we conduct agent-based\nsimulations of growing, dividing, and sterically repelling rod-like bacteria of\nvarious aspect ratios, and we analyze colony morphology using tools from both\nsoft matter physics and population genetics. We find that despite measurable\ndefect self-propulsion in growth-driven active nematics, the radial expansion\nflow prevents chaotic mixing. Even so, at biologically relevant cell aspect\nratios, self-mixing is more effective in growing active nematics of rod-like\ncells compared to growing isotropic colonies of round cells. This suggests\npotential evolutionary consequences associated with active nematic dynamics.",
        "positive": "Pulse propagation in decorated granular chains: An analytical approach: We study pulse propagation in one-dimensional chains of spherical granules\ndecorated with small grains placed between large granules. The effect of the\nsmall granules can be captured by replacing the decorated chains by undecorated\nchains of large granules of appropriately renormalized mass and effective\ninteraction between the large granules. This allows us to obtain simple\nanalytic expressions for the pulse propagation properties using a\ngeneralization of the binary collision approximation introduced in our earlier\nwork [Phys. Rev. E in print (2009); Phys. Rev. E {\\bf 69}, 037601 (2004)]"
    },
    {
        "anchor": "The response of jammed packings to thermal fluctuations: We focus on the response of mechanically stable (MS) packings of\nfrictionless, bidisperse disks to thermal fluctuations, with the aim of\nquantifying how nonlinearities affect system properties at finite temperature.\nPackings of disks with purely repulsive contact interactions possess two main\ntypes of nonlinearities, one from the form of the interaction potential and one\nfrom the breaking (or forming) of interparticle contacts. To identify the\ntemperature regime at which the contact-breaking nonlinearities begin to\ncontribute, we first calculated the minimum temperatures $T_{cb}$ required to\nbreak a single contact in the MS packing for both single and multiple eigenmode\nperturbations of the $T=0$ MS packing. We then studied deviations in the\nconstant volume specific heat $C_V$ and deviations of the average disk\npositions $\\Delta r$ from their $T=0$ values in the temperature regime $T_{cb}\n< T < T_{r}$, where $T_r$ is the temperature beyond which the system samples\nthe basin of a new MS packing. We find that the deviation in the specific heat\nper particle $\\Delta {\\overline C}_V^0/{\\overline C}_V^0$ relative to the zero\ntemperature value ${\\overline C}_V^0$ can grow rapidly above $T_{cb}$, however,\nthe deviation $\\Delta {\\overline C}_V^0/{\\overline C}_V^0$ decreases as\n$N^{-1}$ with increasing system size. To characterize the relative strength of\ncontact-breaking versus form nonlinearities, we measured the ratio of the\naverage position deviations $\\Delta r^{ss}/\\Delta r^{ds}$ for single- and\ndouble-sided linear and nonlinear spring interactions. We find that $\\Delta\nr^{ss}/\\Delta r^{ds} > 100$ for linear spring interactions and is independent\nof system size.",
        "positive": "Correlated disorder in random block-copolymers: We study the effect of a random Flory-Huggins parameter in a symmetric\ndiblock copolymer melt which is expected to occur in a copolymer where one\nblock is near its structural glass transition. In the clean limit the\nmicrophase segregation between the two blocks causes a weak, fluctuation\ninduced first order transition to a lamellar state. Using a renormalization\ngroup approach combined with the replica trick to treat the quenched disorder,\nwe show that beyond a critical disorder strength, that depends on the length of\nthe polymer chain, the character of the transition is changed. The system\nbecomes dominated by strong randomness and a glassy rather than an ordered\nlamellar state occurs. A renormalization of the effective disorder distribution\nleads to nonlocal disorder correlations that reflect strong compositional\nfluctuation on the scale of the radius of gyration of the polymer chains. The\nreason for this behavior is shown to be the chain length dependent role of\ncritical fluctuations, which are less important for shorter chains and become\nincreasingly more relevant as the polymer length increases and the clean first\norder transition becomes weaker."
    },
    {
        "anchor": "Electrorheological study of the nematic LC 4-n-hepthyl-4'-cyanobiphenyl:\n  experimental and theoretical treatment: The experimental and theoretical study of the electrorheological (ER) effect\nobserved in the nematic phase of the 4-n-hepthyl-4'-cyanobiphenyl (K21) is the\naim of this work. The K21 liquid crystal (LC) appears to be a model system\nwhere all the observed rheologial behaviours can be interpreted by the\nLeslie-Ericksen (L-E) continuum theory for low molecular weight liquid\ncrystals. We present the flow curves of our sample for different temperatures\nand under the influence of an external electric field, ranging from 0 to\n3kV/mm, applied perpendicular to the flow direction. We also present the\nviscosity as a function of the temperature, for the same values of electric\nfield, obtained for different shear rates. A master flow curve was built,\ndividing the shear rate by the square of the electric field and multiplying by\nthe square of a reference electric field value, for each temperature, where two\nNewtonian plateaus appear at low and high shear rate values, connected by a\nshear-thinning region at intermediate shear rate values. Theoretical\ninterpretation of the observed behaviours is proposed in the framework of the\ncontinuum theory. In this description the director alignment angle is a\nfunction of the electric field and the flow field - boundary conditions are\nneglected. In this way it was possible to extract some viscoelastic parameters,\nas well as the dielectric anisotropy.",
        "positive": "Phase diagram of a polydisperse soft-spheres model for liquids and\n  colloids: The phase diagram of soft spheres with size dispersion has been studied by\nmeans of an optimized Monte Carlo algorithm which allows to equilibrate below\nthe kinetic glass transition for all sizes distribution. The system\nubiquitously undergoes a first order freezing transition. While for small size\ndispersion the frozen phase has a crystalline structure, large density\ninhomogeneities appear in the highly disperse systems. Studying the interplay\nbetween the equilibrium phase diagram and the kinetic glass transition, we\nargue that the experimentally found terminal polydispersity of colloids is a\npurely kinetic phenomenon."
    },
    {
        "anchor": "Routes to spatiotemporal chaos in the rheology of nematogenic fluids: With a view to understanding the ``rheochaos'' observed in recent experiments\nin a variety of orientable fluids, we study numerically the equations of motion\nof the spatiotemporal evolution of the traceless symmetric order parameter of a\nsheared nematogenic fluid. In particular we establish, by decisive numerical\ntests, that the irregular oscillatory behavior seen in a region of parameter\nspace where the nematic is not stably flow-aligning is in fact spatiotemporal\nchaos. We outline the dynamical phase diagram of the model and study the route\nto the chaotic state. We find that spatiotemporal chaos in this system sets in\nvia a regime of {\\em spatiotemporal intermittency}, with a power-law\ndistribution of the widths of laminar regions, as in H. Chat\\'{e} and P.\nManneville, Phys. Rev. Lett. {\\bf 58}, 112 (1987). Further, the evolution of\nthe histogram of band sizes shows a growing length-scale as one moves from the\nchaotic towards the flow aligned phase. Finally we suggest possible experiments\nwhich can observe the intriguing behaviors discussed here.",
        "positive": "Topological correlations and asymptotic freedom in cellular aggregates: In random cellular systems, both observation and maximum entropy inference\ngive a specific form to the topological pair correlation: it is bi-affine in\nthe cells number of edges with coefficients depending on the distance between\nthe two cells of the pair. Assuming this form for the pair correlations, we\nmake explicit the conditions of statistical independence at large distance.\nWhen, on average, the defects do not contribute, the layer population and the\nenclosed topological charge both increase polynomially with distance. In\ndimension 2, the exponent of the leading terms depend on sum rules satisfied,\nor not, by the maximum entropy coefficients."
    },
    {
        "anchor": "Shear-Induced Anisotropy in Rough Elastomer Contact: True contact between randomly rough solids consists of myriad individual\nmicro-junctions. While their total area controls the adhesive friction force of\nthe interface, other macroscopic features, including viscoelastic friction,\nwear, stiffness and electric resistance, also strongly depend on the size and\nshape of individual micro-junctions. Here we show that, in rough elastomer\ncontacts, the shape of micro-junctions significantly varies as a function of\nthe shear force applied to the interface. This process leads to a growth of\nanisotropy of the overall contact interface, which saturates in macroscopic\nsliding regime. We show that smooth sphere/plane contacts have the same\nshear-induced anisotropic behaviour as individual micro-junctions, with a\ncommon scaling law over four orders of magnitude in initial area. We discuss\nthe physical origin of the observations in the light of a fracture-based\nadhesive contact mechanics model, described in the companion article, which\ncaptures the smooth sphere/plane measurements. Our results shed light on a\ngeneric, overlooked source of anisotropy in rough elastic contacts, not taken\ninto account in current rough contact mechanics models.",
        "positive": "Entropy-Driven Phase Transitions in Colloidal Systems: This thesis can be divided into two independent parts. In the first part of\nthis thesis, we focus on studying the kinetic pathways of nucleation in\ncolloidal systems. In Chapter 2, we briefly introduce the relevant theory of\nnucleation, i.e., classic nucleation theory. Then in Chapter 3, we investigate\nthe crystal nucleation in the \"simplest\" model system for colloids, i.e., the\nmonodisperse hard-sphere system, by using three different simulation methods,\ni.e., molecular dynamics, forward flux sampling and umbrella sampling\nsimulations. Subsequently, we apply our simulation methods to a more realistic\nsystem of colloidal hard spheres in Chapter 4. Furthermore, we study the\nnucleation in a variety of systems consisting of hard particles, i.e., hard\ndumbbells (Chapter 5), hard rods (Chapter 6), hard colloidal polymers (Chapter\n7) and binary hard-sphere mixtures (Chapter 8). In the second part of this\nthesis, we study the phase behavior of several colloidal systems. In Chapter 9,\nwe study the equilibrium phase diagram of colloidal hard superballs whose shape\ninterpolates from cubes to octahedra via spheres. We investigate the\nmicellization of asymmetric patchy dumbbells induced by the depletion\nattraction in Chapter 10."
    },
    {
        "anchor": "Distinguished rheological models in the framework of a thermodynamical\n  internal variable theory: We present and analyze a thermodynamical theory of rheology with single\ninternal variable. The universality of the model is ensured as long as the\nmesoscopic and/or microscopic background processes satisfy the applied\nthermodynamical principles, which are the second law, the basic balances and\nthe existence of an additional-tensorial-state variable. The resulting model,\nwhich we suggest to call the Kluitenberg-Verh\\'as body, is the\nPoynting-Thomson-Zener body with an additional inertial element, or, in other\nwords, is the extension of Jeffreys model to solids. We argue that this\nKluitenberg-Verh\\'as body is the natural thermodynamical building block of\nrheology. An important feature of the presented methodology is that nontrivial\ninequality-type restrictions arise for the four parameters of the model. We\ncompare these conditions and other aspects to those of other known\nthermodynamical approaches, like Extended Irreversible Thermodynamics or the\noriginal theory of Kluitenberg.",
        "positive": "Study of Aqueous Dispersions of Magnetic Nanoparticles by Magnetic and\n  Rheological Measurements: The observed magnetic tunability of light transmission through a ferrofluid\ncan be effectively understood in terms of the inter-particle interaction that\ncan be estimated from the magnetic and rheological properties of these fluids.\nThe present study reports complementary magnetic and rheological measurements\nof aqueous dispersions of ferrite nanoparticles and a commercial ferrofluid.\nThe room temperature magnetization measured in a SQUID magnetometer up to\nfields of 1 to 2 Tesla showed superparamagnetic behaviour of the particles and\nthe dispersion with the background signal of the liquid showing a diamagnetic\nbehaviour. The room temperature rheological behaviour in zero magnetic field of\nthe fluids was investigated by measuring the viscosity as a function of shear\nrate from 1-100 s-1. The particle size and the nature of the carrier liquid\ndetermine the viscosity and is expected to have an effect on the inter-particle\ninteraction."
    },
    {
        "anchor": "Bidirectional particle transport and size selective sorting of Brownian\n  particles in a flashing spatially periodic energy landscape: We demonstrate a size sensitive experimental scheme which enables\nbidirectional transport and fractionation of paramagnetic colloids in a fluid\nmedium. It is shown that two types of magnetic colloidal particles with\ndifferent sizes can be simultaneously transported in opposite directions, when\ndeposited above a stripe-patterned ferrite garnet film subjected to a\nsquare-wave magnetic modulation. Due to their different sizes, the particles\nare located at distinct elevations above the surface, and they experience two\ndifferent energy landscapes, generated by the modulated magnetic substrate. By\ncombining theoretical arguments and numerical simulations, we reveal such\nenergy landscapes, which fully explain the bidirectional transport mechanism.\nThe proposed technique does not require pre-imposed channel geometries such as\nin conventional microfluidics or lab-on-a-chip systems, and permits remote\ncontrol over the particle motion, speed and trajectory, by using relatively low\nintense magnetic fields.",
        "positive": "Slippery but tough - the rapid fracture of lubricated frictional\n  interfaces: We study the onset of friction for rough contacting blocks whose interface is\ncoated with a thin lubrication layer. High speed measurements of the real\ncontact area and stress fields near the interface reveal that propagating shear\ncracks mediate lubricated frictional motion. While lubricants reduce interface\nresistances, surprisingly, they significantly increase energy dissipated,\n$\\Gamma$, during rupture. Moreover, lubricant viscosity affects the onset of\nfriction but has no effect on $\\Gamma$. Fracture mechanics provide a new way to\nview the otherwise hidden complex dynamics of the lubrication layer."
    },
    {
        "anchor": "The Smectic $A$-$C$ Phase Transition in Biaxial Disordered Environments: We study the smectic $A$-$C$ phase transition in biaxial disordered\nenvironments, e.g. fully anisotropic aerogel. We find that both the $A$ and $C$\nphases belong to the universality class of the \"XY Bragg glass\", and therefore\nhave quasi-long-ranged translational smectic order. The phase transition itself\nbelongs to a new universality class, which we study using an $\\epsilon=7/2-d$\nexpansion. We find a stable fixed point, which implies a continuous transition,\nthe critical exponents of which we calculate.",
        "positive": "A unified picture of roto-translational dynamics in aqueous polyatomic\n  ions: Mode-coupling theory provides a unified description of the rotational and\ntranslational dynamics of polyatomic ions. These molecular ions are distinct\nfrom usual models of ion diffusion, such as K+ , Cl- etc., and also different\nfrom rotational dynamics of dipolar molecules often modeled in dielectric\ncontinuum models as point dipoles. Both these approaches are untenable for\npolyatomic ions. Here rotational and translational dynamics are so strongly\ncoupled that one obtains a more coherent description by treating them together.\nWe carry out theoretical and computational studies of a series of well-known\npolyatomic ions, namely sulfate, nitrate and acetate ions. All the three ions\nexhibit different rotational diffusivity, with that of nitrate ion being\nconsiderably larger than the other two. They all defy the hydrodynamic laws of\nsize dependence. Study of the local structure around the ions provides valuable\ninsight into the origin of these differences. We carry out a detailed study of\nthe rotational diffusion of these ions by extensive computer simulation and\nusing the theoretical approaches of the dielectric friction developed by\nFatuzzo-Mason (FM) and Nee-Zwanzig (NZ), and subsequently generalized by Alavi\nand Waldeck. We develop a self-consistent mode-coupling theory (SC-MCT)\nformalism that helps elucidating the role of coupling between translational and\nrotational motion of these ions. In fact, these two motions self-consistently\ndetermine the value of each other. The RISM-based MCT suggests an interesting\nrelation between the torque-torque and the force-force time correlation\nfunction with the proportionality constant being determined by the geometry and\nthe charge distribution of the polyatomic molecule.We point out several\nparallelism between the theories of translational and rotation friction\ncalculations of ions in dipolar liquids."
    },
    {
        "anchor": "Measuring Spatial Distribution of Local Elastic Modulus in Glasses: Glasses exhibit spatially inhomogeneous elastic properties, which can be\ninvestigated by measuring their elastic moduli at a local scale. Various\nmethods to evaluate the local elastic modulus have been proposed in the\nliterature. A first possibility is to measure the local stress-local strain\ncurve and to obtain the local elastic modulus from the slope of the curve, or\nequivalently to use a local fluctuation formula. Another possible route is to\nassume an affine strain and to use the applied global strain instead of the\nlocal strain for the calculation of the local modulus. Most recently a third\ntechnique has been introduced, which is easy to be implemented and has the\nadvantage of low computational cost. In this contribution, we compare these\nthree approaches by using the same model glass and reveal the differences among\nthem caused by the non-affine deformations.",
        "positive": "Realization and Properties of Biochemical-Computing Biocatalytic XOR\n  Gate Based on Enzyme Inhibition by a Substrate: We consider a realization of the XOR logic gate in a process biocatalyzed by\nan enzyme (here horseradish peroxidase: HRP), the function of which can be\ninhibited by a substrate (hydrogen peroxide for HRP), when the latter is\ninputted at large enough concentrations. A model is developed for describing\nsuch systems in an approach suitable for evaluation of the analog noise\namplification properties of the gate. The obtained data are fitted for gate\nquality evaluation within the developed model, and we discuss aspects of\ndevising XOR gates for functioning in \"biocomputing\" systems utilizing\nbiomolecules for information processing."
    },
    {
        "anchor": "Noise and diffusion of a vibrated self-propelled granular particle: Granular materials are an important physical realization of active matter. In\nvibration-fluidized granular matter, both diffusion and self-propulsion derive\nfrom the same collisional forcing, unlike many other active systems where there\nis a clean separation between the origin of single-particle mobility and the\ncoupling to noise. Here we present experimental studies of single-particle\nmotion in a vibrated granular monolayer, along with theoretical analysis that\ncompares grain motion at short and long time scales to the assumptions and\npredictions, respectively, of the active Brownian particle (ABP) model. The\nresults demonstrate that despite the unique relation between noise and\npropulsion, granular media do show the generic features predicted by the ABP\nmodel and indicate that this is a valid framework to predict collective\nphenomena. Additionally, our scheme of analysis for validating the inputs and\noutputs of the model can be applied to other granular and non-granular systems.",
        "positive": "Mean-field phase diagram of cold lattice bosons in disordered potentials: We show that a site-dependent mean-field approach captures the quantum phases\nof the disordered Bose-Hubbard model commonly adopted to describe ultracold\nbosons in random optical lattice potentials. The different phases, namely\nsuperfluid, Mott insulator, Bose-glass and -- at finite temperature -- normal\nfluid, are characterized by means of the superfluid and condensate fractions,\nand compressibility of the system. We point out that both the boundaries of the\nMott lobes and the nature of the phase surrounding them are related to the\nspectral features of a purely off-diagonal non-interacting Anderson model. We\ncompare our results to other works."
    },
    {
        "anchor": "Mode Coupling and Dynamical Heterogeneity in Colloidal Gelation: A\n  Simulation Study: We present simulation results addressing the dynamics of a colloidal system\nwith attractive interactions close to gelation. Our interaction also has a\nsoft, long range repulsive barrier which suppresses liquid-gas type phase\nseparation at long wavelengths. The new results presented here lend further\nweight to an intriguing picture emerging from our previous simulation work on\nthe same system. Whereas mode coupling theory (MCT) offers quantitatively good\nresults for the decay of correlators, closer inspection of the dynamics reveals\na bimodal population of fast and slow particles with a very long exchange\ntimescale. This population split represents a particular form of dynamic\nheterogeneity (DH). Although DH is usually associated with activated hopping\nand/or facilitated dynamics in glasses, the form of DH observed here may be\nmore collective in character and associated with static (i.e., structural)\nheterogeneity.",
        "positive": "Nonstationary models for liquid crystals: A fresh mathematical\n  perspective: In this article we discuss nonstationary models for inhomogeneous liquid\ncrystals driven out of equilibrium by flow. Emphasis is put on those models\nwhich are used in the mathematics as well as in the physics literature, the\noverall goal being to illustrate the mathematical progress on popular models\nwhich physicists often just solve numerically. Our discussion includes the\nDoi--Hess model for the orientational distribution function, the $Q$-tensor\nmodel and the Ericksen--Leslie model which focuses on the director dynamics. We\nsurvey particularly the mathematical issues (such as existence of solutions)\nand linkages between these models. Moreover, we introduce the new concept of\nrelative energies measuring the distance between solutions of equation systems\nwith nonconvex energy functionals and discuss possible applications of this\nconcept for future studies."
    },
    {
        "anchor": "Sound damping in frictionless granular materials: The interplay between\n  configurational disorder and inelasticity: We numerically investigate sound damping in a model of granular materials in\ntwo dimensions. We simulate evolution of standing waves in disordered\nfrictionless disks and analyze their damped oscillations by velocity\nautocorrelation functions and power spectra. We control the strength of\ninelastic interactions between the disks in contact to examine the effect of\nenergy dissipation on sound characteristics of disordered systems. Increasing\nthe strength of inelastic interactions, we find that (i) sound softening\nvanishes and (ii) sound attenuation due to configurational disorder, i.e. the\nRayleigh scattering at low frequencies and disorder-induced broadening at high\nfrequencies, is completely dominated by the energy dissipation. Our findings\nsuggest that sound damping in granular media is determined by the interplay\nbetween elastic heterogeneities and inelastic interactions.",
        "positive": "Effect of surfactant concentration on the responsiveness of a\n  thermoresponsive copolymer/surfactant mixture with potential application on\n  Smart foams formulations: We studied a system formed by a mixture of a thermoresponsive negatively\ncharged graft copolymer (Alg-g-PNIPAAm) with a brush-type structure, and an\noppositely charged surfactant (DTAB), in bulk and at the air-solution\ninterface. We performed experiments of surface tension, electrophoretic\nmobility, dynamic and static light scattering and atomic force microscopy in\norder to characterize the complexes formed as a function of DTAB concentration\nand temperature. We found that these polymer-surfactant complexes are able to\nrespond by changing their sizes, both in bulk and at the air-solution\ninterface, when T is increased above the coil-globule transition temperature\n(LSCT) of the copolymer. However, the thermoresponse was found to be dependent\non surfactant concentration, cs: for cs < 2.8 mM, the size of the aggregates\ndecreases as T increases but, for cs >= 2.8 mM, the opposite behavior takes\nplace, i.e. the size increases with T. At the interface, the intensity of the\neffect produced on the surface tension by increasing T above LCST diminishes\ncontinuously as cs increases, reducing the ability of the interfacial complex\nto respond to temperature changes. We studied the stability of aqueous foams\nformulated with these mixtures as a function of T and cs. We found that the\nstability of the foam can be modulated by changing T, but we observed that this\neffect is dependent on the surfactant concentration range. We found a\ncorrelation between changes in the aggregates sizes, the surface tension\nbehavior and the responsiveness of foam stability to changes of temperature."
    },
    {
        "anchor": "Multiscale dynamics of colloidal deposition and erosion in porous media: Diverse processes -- e.g., environmental pollution, groundwater remediation,\noil recovery, filtration, and drug delivery -- involve the transport of\ncolloidal particles in porous media. Using confocal microscopy, we directly\nvisualize this process in situ and thereby identify the fundamental mechanisms\nby which particles are distributed throughout a medium. At high injection\npressures, hydrodynamic stresses cause particles to be continually deposited on\nand eroded from the solid matrix -- notably, forcing them to be distributed\nthroughout the entire medium. By contrast, at low injection pressures, the\nrelative influence of erosion is suppressed, causing particles to localize near\nthe inlet of the medium. Unexpectedly, these macroscopic distribution behaviors\ndepend on imposed pressure in similar ways for particles of different charges,\nalthough the pore-scale distribution of deposition is sensitive to particle\ncharge. These results reveal how the multiscale interactions between fluid,\nparticles, and the solid matrix control how colloids are distributed in a\nporous medium.",
        "positive": "Connecting Relaxation Time to a Dynamical Length Scale in Athermal\n  Active Glass Formers: Supercooled liquids display dynamics that are inherently heterogeneous in\nspace. This essentially means that at temperatures below the melting point,\nparticle dynamics in certain regions of the liquid can be orders of magnitude\nfaster than other regions. Often dubbed as dynamical heterogeneity, this\nbehavior has fascinated researchers involved in the study of glass transition,\nfor over two decades. A fundamentally important question in all glass\ntransition studies is whether one can connect the growing relaxation time to a\nconcomitantly growing length scale. In this paper, we go beyond the realm of\nordinary glass forming liquids and study the origin of a growing dynamical\nlength scale $\\xi$ in a self propelled \"active\" glass former. This length scale\nwhich is constructed using structural correlations agrees well with the average\nsize of the clusters of slow moving particles that are formed as the liquid\nbecomes spatially heterogeneous. We further report that the concomitantly\ngrowing $\\alpha$- relaxation time exhibits a simple scaling law, $\\tau_\\alpha\n\\sim \\text{exp} (\\xi \\mu / T_{eff})$, with $\\mu$ as an effective chemical\npotential, $T_{eff}$ as the effective temperature, and $\\xi \\mu$ as the growing\nfree energy barrier for cluster rearrangements. The findings of our study are\nvalid over three decades of persistence times, and hence could be very useful\nin understanding the slow dynamics of a generic active liquid such as an active\ncolloidal suspension, or a self propelled granular medium, to mention a few."
    },
    {
        "anchor": "Correlated rigidity percolation in fractal lattices: Rigidity percolation (RP) is the emergence of mechanical stability in\nnetworks. Motivated by the experimentally observed fractal nature of materials\nlike colloidal gels and disordered fiber networks, we study RP in a fractal\nnetwork. Specifically, we calculate the critical packing fractions of\nsite-diluted lattices of Sierpi\\'nski gaskets (SG's) with varying degrees of\nfractal iteration. Our results suggest that although the correlation length\nexponent and fractal dimension of the RP of these lattices are identical to\nthat of the regular triangular lattice, the critical volume fraction is\ndramatically lower due to the fractal nature of the network. Furthermore, we\ndevelop a simplified model for an SG lattice based on the fragility analysis of\na single SG. This simplified model provides an upper bound for the critical\npacking fractions of the full fractal lattice, and this upper bound is strictly\nobeyed by the disorder averaged RP threshold of the fractal lattices. Our\nresults characterize rigidity in ultra-low-density fractal networks.",
        "positive": "Reversibility and hysteresis of the sharp yielding transition of a\n  colloidal glass under oscillatory shear: The mechanical response of glasses remains challenging to understand. Recent\nresults indicate that the oscillatory rheology of soft glasses is accompanied\nby a sharp non-equilibrium transition in the microscopic dynamics. Here, we use\nsimultaneous x-ray scattering and rheology to investigate the reversibility and\nhysteresis of the sharp sharp symmetry change from anisotropic solid to\nisotropic liquid dynamics observed in the oscillatory shear of colloidal\nglasses [D. V. Denisov, M. T. Dang, B. Struth, A. Zaccone, and P. Schall, Sci.\nRep. 5, 14359 (2015)]. We use strain sweeps with increasing and decreasing\nstrain amplitude to show that, in analogy to equilibrium transitions, this\nsharp symmetry change is reversible and exhibits systematic frequency-dependent\nhysteresis. Using the non-affine response formalism of amorphous solids, we\nshow that these hysteresis effects arise from frequency-dependent non-affine\nstructural cage rearrangements at large strain. These results consolidate the\nfirst-order like nature of the oscillatory shear transition and quantify\nrelated hysteresis effects both via measurements and theoretical modelling."
    },
    {
        "anchor": "Flow of anisometric particles in a quasi-2D hopper: The stationary flow field in a quasi-two-dimensional hopper is investigated\nexperimentally. The behavior of materials consisting of beads and elongated\nparticles with different aspect ratio is compared. We show, that while the\nvertical velocity in the flowing region can be fitted with a Gaussian function\nfor beads, in the case of elongated grains the flowing channel is narrower and\nis bordered with sharper velocity gradient. For this case, we quantify\ndeviations from the Gaussian velocity profile. Relative velocity fluctuations\nare considerably larger and slower for elongated grains.",
        "positive": "Micromorphic FE$^2$ Simulation of Plastic Deformations of Foam\n  Structures: Capturing and predicting the effective mechanical properties of highly porous\ncellular media still represents a significant challenge for the research\ncommunity, due to their complex structural interdependencies and known size\neffects. Micromorphic theories are often applied in this context to model the\ninelastic deformation behavior of foam-like structures, in particular to\nincorporate such size effect into the investigation of structure-property\ncorrelations. This raises the problems of formulating appropriate constitutive\nrelations for the numerous non-classical stress measures and determining the\ncorresponding material parameters, which are usually difficult to assess\nexperimentally. The present contribution therefore alternatively employs a\nconcurrent micromorphic multi-scale approach within the Direct FE$^2$ framework\nto simulate the complex irreversible behavior of foam-like porous solids. The\npredictions of Cosserat (micropolar) and a fully-micromorphic theory are\ncompared with conventional FE$^2$ results and direct numerical simulations\n(DNS) for complex loading scenarios with elastic, elastic-plastic, and creep\ndeformations."
    },
    {
        "anchor": "Mode Coupling Theory for Nonequilibrium Glassy Dynamics of Thermal\n  Self-Propelled Particles: We present a promising mode coupling theory study for the relaxation and\nglassy dynamics of a system of strongly interacting self-propelled particles,\nwherein the self-propulsion force is described by Ornstein-Uhlenbeck colored\nnoise and thermal noises are included. Our starting point is an effective\nSmoluchowski equation governing the distribution function of particle's\npositions, from which we derive a memory function equation for the time\ndependence of density fluctuations in nonequilibrium steady states. With the\nbasic assumption of absence of macroscopic currents and standard mode coupling\napproximation, we can obtain expressions for the irreducible memory function\nand other relevant dynamic terms. With these equations obtained, we study the\nglassy dynamics of this thermal self-propelled particles system by\ninvestigating the Debye-Waller factor f_{q} and relaxation time \\tau_{\\alpha}\nas functions of the persistence time \\tau_{p} of self-propulsion, the single\nparticle effective temperature T_{\\text{eff}} as well as the number density\n\\rho. Consequently, we find the critical density \\rho_{c} for given \\tau_{p}\nshifts to larger values with increasing magnitude of propulsion force or\neffective temperature, in good accordance with previous reported simulation\nworks. In addition, the theory facilitates us to study the critical effective\ntemperature T_{\\text{eff}}^{c} for fixed \\rho as well as its dependence on\n\\tau_{p}. We find that T_{\\text{eff}}^{c} increases with \\tau_{p} and in the\nlimit \\tau_{p}\\to0, it approaches the value for a simple passive Brownian\nsystem as expected. Our theory also well recovers the results for passive\nsystems and can be easily extended to more complex systems such as\nactive-passive mixtures.",
        "positive": "Modelling how curved active proteins and shear flow pattern cellular\n  shape and motility: Cell spreading and motility on an adhesive substrate are driven by the active\nphysical forces generated by the actin cytoskeleton. We have recently shown\nthat coupling curved membrane complexes to protrusive forces, exerted by the\nactin polymerization that they recruit, provides a mechanism that can give rise\nto spontaneous membrane shapes and patterns. In the presence of an adhesive\nsubstrate, this model was shown to give rise to an emergent motile phenotype,\nresembling a motile cell. Here, we utilize this ``minimal-cell\" model to\nexplore the impact of external shear flow on the cell shape and migration on a\nuniform adhesive flat substrate. We find that in the presence of shear the\nmotile cell reorients such that its leading edge, where the curved active\nproteins aggregate, faces the shear flow. The flow-facing configuration is\nfound to minimize the adhesion energy by allowing the cell to spread more\nefficiently over the substrate. For the non-motile vesicle shapes, we find that\nthey mostly slide and roll with the shear flow. We compare these theoretical\nresults with experimental observations, and suggest that the tendency of many\ncell types to move against the flow may arise from the very general, and\nnon-cell-type-specific mechanism predicted by our model."
    },
    {
        "anchor": "Phase ordering, transformation, and grain growth of two-dimensional\n  binary colloidal crystals: A phase field crystal modeling: The formation and dynamics of a wide variety of binary two-dimensional\nordered structures and superlattices are investigated through a phase field\ncrystal model with sublattice ordering. Various types of binary ordered phases,\nthe phase diagrams, and the grain growth dynamics and structural transformation\nprocesses, including the emergence of topological defects, are examined. The\nresults are compared to the ordering and assembly of two-component colloidal\nsystems. Two factors governing the binary phase ordering are identified, the\ncoupling and competition between the length scales of two sublattices and the\nselection of average particle densities of two components. The control and\nvariation of these two factors lead to the prediction of various complex binary\nordered patterns, with different types of sublattice ordering for integer vs.\nnoninteger ratios of sublattice length scales. These findings will enable\nfurther systematic studies of complex ordering and assembly processes of binary\nsystems particularly binary colloidal crystals.",
        "positive": "Diffusion of a ring polymer in good solution via the Brownian dynamics: Diffusion constants D_{R} and D_{L} of ring and linear polymers of the same\nmolecular weight in a good solvent, respectively, have been evaluated through\nthe Brownian dynamics with hydrodynamic interaction. The ratio $C=D_{R}/D_{L}$,\nwhich should be universal in the context of the renormalization group, has been\nestimated as $C= 1.11 \\pm 0.01$ for the large-N limit. It should be consistent\nwith that of synthetic polymers, while it is smaller than that of DNAs such as\n$C \\approx 1.3$. Furthermore, the probability of the ring polymer being a\nnontrivial knot is found to be very small, while bond crossings may occur at\nalmost all time steps in the present simulation that realizes the good solvent\nconditions."
    },
    {
        "anchor": "Soap Froths and Crystal Structures: We propose a physical mechanism to explain the crystal symmetries found in\nmacromolecular and supramolecular micellar materials. We argue that the packing\nentropy of the hard micellar cores is frustrated by the entropic interaction of\ntheir brush-like coronas. The latter interaction is treated as a surface effect\nbetween neighboring Voronoi cells. The observed crystal structures correspond\nto the Kelvin and Weaire-Phelan minimal foams. We show that these structures\nare stable for reasonable areal entropy densities.",
        "positive": "Order-preserving dynamics in one dimension -- single-file diffusion and\n  caging from the perspective of dynamical density functional theory: Dynamical density functional theory (DDFT) is a powerful variational\nframework to study the nonequilibrium properties of colloids by only\nconsidering a time-dependent one-body number density. Despite the large number\nof recent successes, properly modeling the long-time dynamics in interacting\nsystems within DDFT remains a notoriously difficult problem, since structural\ninformation, accounting for temporary or permanent particle cages, gets lost.\nHere we address such a caging scenario by reducing it to a clean\none-dimensional problem, where the particles are naturally ordered (arranged on\na line) by perfect cages created by their two next neighbors. In particular, we\nconstruct a DDFT approximation based on an equilibrium system with an\nasymmetric pair potential, such that the corresponding one-body densities still\ncarry the footprint of particle order. Applied to a system of confined hard\nrods, this order-preserving dynamics (OPD) yields exact results at the system\nboundaries, in addition to the imprinted correct long-time behavior of density\nprofiles representing individual particles. In an open system, our approach\ncorrectly reproduces the reduced long-time diffusion coefficient and\nsubdiffusion, characteristic for a single-file setup. These observations cannot\nbe made using current forms of DDFT without particle order."
    },
    {
        "anchor": "Energy Landscape and Overlap Distribution of Binary Lennard-Jones\n  Glasses: We study the distribution of overlaps of glassy minima, taking proper care of\nresidual symmetries of the system. Ensembles of locally stable, low lying\nglassy states are efficiently generated by rapid cooling from the liquid phase\nwhich has been equilibrated at a temperature $T_{run}$. Varying $T_{run}$, we\nobserve a transition from a regime where a broad range of states are sampled to\na regime where the system is almost always trapped in a metastable glassy\nstate. We do not observe any structure in the distribution of overlaps of\nglassy minima, but find only very weak correlations, comparable in size to\nthose of two liquid configurations.",
        "positive": "Elastocaloric effect in amorphous polymer networks undergoing\n  mechanotropic phase transitions: Deformations of amorphous polymer networks prepared with significant\nconcentrations of liquid crystalline mesogens have been recently reported to\nundergo mechanotropic phase transitions. Here, we report that these\nmechanotropic phase transitions are accompanied by an elastocaloric response\n($\\Delta T = 2.9 \\text{ K}$). Applied uniaxial strain to the elastomeric\npolymer network transitions the organization of the material from a disordered,\namorphous state (order parameter $Q=0$) to the nematic phase ($Q=0.47$). Both\nthe magnitude of the elastocaloric temperature change and mechanically induced\norder parameter are dependent on the concentration of liquid crystal mesogens\nin the material. While the observed temperature changes in these materials are\nsmaller than those observed in shape memory alloys, the responsivity, defined\nas the temperature change divided by the input stress, is larger by an order of\nmagnitude."
    },
    {
        "anchor": "Universal power law in the orientational relaxation in thermotropic\n  liquid crystals: We observe a surprisingly general power law decay at short to intermediate\ntimes in orientational relaxation in a variety of model systems (both calamitic\nand discotic, and also discrete) for thermotropic liquid crystals. As all these\nsystems transit across the isotropic-nematic phase boundary, two power law\nrelaxation regimes, separated by a plateau, emerge giving rise to a step-like\nfeature (well-known in glassy liquids) in the single-particle second-rank\norientational time correlation function. In contrast to its probable dynamical\norigin in supercooled liquids, we show that the power law here can originate\nfrom the thermodynamic fluctuations of the orientational order parameter,\ndriven by the rapid growth in the second-rank orientational correlation length.",
        "positive": "Coarse-Graining Simulation Approaches for Polymer Melts: Range of\n  Potential and Computational Efficiency: The integral equation coarse-graining (IECG) approach is a promising\nhigh-level coarse-graining (CG) method for polymer melts, with variable\nresolution from soft spheres to multi CG sites, which preserves the structural\nand thermodynamical consistencies with the related atomistic simulations. When\ncompared to the atomistic description, the procedure of coarse-graining results\nin smoother free energy surfaces, longer-ranged potentials, a decrease in the\nnumber of interaction sites for a given polymer, and more. Because these\nchanges have competing effects on the computational efficiency of the CG model,\ncare needs to be taken when studying the effect of coarse-graining on the\ncomputational speed-up in CG molecular dynamics simulations. For instance,\ntreatment of long-range CG interactions requires the selection of cutoff\ndistances that include the attractive part of the effective CG potential and\nforce. In particular, we show how the complex nature of the range and curvature\nof the effective CG potential, the selection of a suitable CG timestep, the\nchoice of the cutoff distance, the molecular dynamics algorithms, and the\nsmoothness of the CG free energy surface affect the efficiency of IECG\nsimulations. By direct comparison with the atomistic simulations of relatively\nshort chain polymer melts, we find that the overall computational efficiency is\nhighest for the highest level of CG (soft spheres), with an overall improvement\nof the computational efficiency being about $10^6-10^8$ for various CG\nlevels/resolutions. Therefore, the IECG method can have important applications\nin molecular dynamics simulations of polymeric systems. Finally, making use of\nthe standard spatial decomposition algorithm, the parallel scalability of the\nIECG simulations for various levels of CG is presented. Optimal parallel\nscaling is observed for a reasonably large number of processors."
    },
    {
        "anchor": "The role of curvature anisotropy in the ordering of spheres on an\n  ellipsoid: Non-spherical emulsion droplets can be stabilized by densely packed colloidal\nparticles adsorbed at their surface. In order to understand the microstructure\nof these surface packings, the ordering of hard spheres on ellipsoidal surfaces\nis determined through large scale computer simulations. Defects in the packing\nare shown generically to occur most often in regions of strong curvature;\nhowever, the relationship between defects and curvature is nontrivial, and the\ndistribution of defects shows secondary maxima for ellipsoids of sufficiently\nhigh aspect ratio. As with packings on spherical surfaces, additional defects\nbeyond those required by topology are observed as chains or 'scars'. The\ntransition point, however, is found to be softened by the anisotropic curvature\nwhich also partially orients the scars. A rich library of symmetric\ncommensurate packings are identified for low particle number. We verify\nexperimentally that ellipsoidal droplets of varying aspect ratio can be\narrested by surface-adsorbed colloids.",
        "positive": "A Coarse-grained Model for Aqueous Two-phase Systems: Application to\n  Ferrofluids: Aqueous two-phase systems (ATPSs), that is, phase-separating solutions of\nwater soluble but mutually immiscible molecular species, offer fascinating\nprospects for selective partitioning, purification, and extraction. Here, we\nformulate a general Brownian dynamics based coarse-grained simulation model for\na polymeric ATPS comprising two water soluble but mutually immiscible polymer\nspecies. A third solute species, representing, e.g., nanoparticles (NPs),\nadditional macromolecular species, or impurities can readily be incorporated\ninto the model. We demonstrate that the model captures satisfactorily the phase\nseparation, partitioning, and interfacial properties of a model ATPS composed\nof a polymer mixture of dextran and polyethylene glycol (PEG) in which magnetic\nNPs selectively partition into one of the two polymeric phases. The NP\npartitioning is characterized both via the computational model and\nexperimentally under different conditions. The simulation model captures the\ntrends observed in the experiments and quantitatively links the partitioning\nbehavior to the component species interactions. Finally, the response of the\nsimulation model to external magnetic field, with the magnetic NPs as the\nadditional partitioned component, shows that the ATPS interface fluctuations\ncan be controlled by the magnetic field at length scales much smaller than\nthose probed experimentally to date."
    },
    {
        "anchor": "Cascade kernels for models of the turbulent fluid cascade: This paper presents calculations of the Castaing (Physica D, 46, 177, 1990)\ncascade kernels for five well-known models of the turbulent cascade and\ndemonstrates that these kernels provide conceptually simple and direct\ndescriptions of turbulence models equivalent to their multifractal spectra. The\nproblem with a log-normal model seems to be that its Castaing kernel predicts a\nsmall but non-zero probability that finite-amplitude turbulence will decay to\narbitrarily large turbulent amplitudes at smaller scales. Kernels for\nlog-Poisson models do not have this pathology. It is shown how kernels evolve\nwhen the cascade model itself varies with scale. Future studies of other\nkernels compatible with and even dictated by detailed fluid physics may assist\nunderstanding of the turbulent cascade.",
        "positive": "Current-mediated synchronization of a pair of beating non-identical\n  flagella: The basic phenomenology of experimentally observed synchronization (i.e., a\nstochastic phase locking) of identical, beating flagella of a biflagellate alga\nis known to be captured well by a minimal model describing the dynamics of\ncoupled, limit-cycle, noisy oscillators (known as the noisy Kuramoto model). As\ndemonstrated experimentally, the amplitudes of the noise terms therein, which\nstem from fluctuations of the rotary motors, depend on the flagella length.\nHere we address the conceptually important question which kind of synchrony\noccurs if the two flagella have different lengths such that the noises acting\non each of them have different amplitudes. On the basis of a minimal model,\ntoo, we show that a different kind of synchrony emerges, and here it is\nmediated by a current carrying, steady-state; it manifests itself via\ncorrelated \"drifts\" of phases. We quantify such a synchronization mechanism in\nterms of appropriate order parameters $Q$ and $Q_{\\cal S}$ - for an ensemble of\ntrajectories and for a single realization of noises of duration ${\\cal S}$,\nrespectively. Via numerical simulations we show that both approaches become\nidentical for long observation times ${\\cal S}$. This reveals an ergodic\nbehavior and implies that a single-realization order parameter $Q_{\\cal S}$ is\nsuitable for experimental analysis for which ensemble averaging is not always\npossible."
    },
    {
        "anchor": "Direct numerical simulations of rigid body dispersions. I.\n  Mobility/Friction tensors of assemblies of spheres: An improved formulation of the Smoothed Profile method is introduced to\nperform direct numerical simulations of arbitrary rigid body dispersions in a\nNewtonian host solvent. Previous implementations of the method were restricted\nto spherical particles, severely limiting the types of systems that could be\nstudied. The validity of the method is carefully examined by computing the\nfriction/mobility tensors for a wide variety of geometries and comparing them\nto reference values obtained from accurate solutions to the Stokes-Equation.",
        "positive": "Determination of Finite Size Effect in Lattice Models From the Local\n  Height Difference Distribution: Growth of interfaces during vapor deposition is analyzed on a discrete\nlattice. It leads to finding distribution of local heights, measurable for any\nlattice model. Invariance in the change of this distribution in time is used to\ndetermine the finite size effects in various models The analysis is applied to\nthe discrete linear growth equation and Kardar-Parisi-Zhang (KPZ) equation.\n  A new model is devised that shows early convergence to the KPZ dynamics.\n  Various known conservative and non conservative models are tested on a one\ndimensional substrate by comparing the growth results with the exact KPZ and\nlinear growth equation results. The comparison helps in establishing the\ncondition that helps in determining the presence of finite size effect for the\ngiven model. The new model is used in 2+1 dimensions to predict close to the\ntrue value of roughness constant for KPZ equation."
    },
    {
        "anchor": "A Dissipative-Particle-Dynamics Model for Simulating Dynamics of Charged\n  Colloid: A mesoscopic colloid model is developed in which a spherical colloid is\nrepresented by many interacting sites on its surface. The hydrodynamic\ninteractions with thermal fluctuations are taken accounts in full using\nDissipative Particle Dynamics, and the electrostatic interactions are simulated\nusing Particle-Particle-Particle Mesh method. This new model is applied to\ninvestigate the electrophoretic mobility of a charged colloid under an external\nelectric field, and the influence of salt concentration and colloid charge are\nsystematically studied. The simulation results show good agreement with\npredictions from the electrokinetic theory.",
        "positive": "Topological Defects in Twisted Bundles of Two-Dimensionally Ordered\n  Filaments: Twisted assemblies of filaments in ropes, cables and bundles are essential\nstructural elements in wide use in macroscopic materials as well as within the\ncells and tissues of living organisms. We develop the unique, non-linear\nelastic properties of twisted filament bundles that derive from generic\nproperties of two-dimensional line-ordered materials. Continuum elasticity\nreveals a formal equivalence between the elastic stresses induced by bundle\ntwist and those induced by the positive curvature in thin, elastic sheets.\nThese geometrically-induced stresses can be screened by 5-fold disclination\ndefects in lattice packing, and we predict a discrete spectrum elastic energy\ngroundstates associated with integer numbers of disclinations in cylindrical\nbundles. Finally, we show that elastic-energy groundstates are extremely\nsensitive to defect position in the cross-section, with off-center\ndisclinations driving the entire bundle to buckle, adopting globally writhing\nconfigurations."
    },
    {
        "anchor": "Coarse Graining in Block Copolymer Films: We present few ordering mechanisms in block copolymer melts in the\ncoarse-graining approach. For chemically homogeneous or modulated confining\nsurfaces, the surface ordering is investigated above and below the\norder-disorder temperature. In some cases the copolymer deformation near the\nsurface is similar to the copolymer morphology in bulk grain boundaries. Block\ncopolymers in contact with rough surfaces are considered as well, and the\ntransition from lamellae parallel to perpendicular to the surface is\ninvestigated as a function of surface roughness. Finally, we describe how\nexternal electric fields can be used to align block copolymer meso-phases in a\ndesired direction, or to induce an order-order phase transition, and dwell on\nthe role of mobile dissociated ions on the transition.",
        "positive": "On Slow Dynamic Elasticity at short times: It has been reported that slow dynamic nonlinear elastic relaxations, widely\nthought to proceed in proportion to the logarithm of time since mechanical\nconditioning ceases, recover at a diminished rate at early times, with a time\nof transition that varies with the grain size of the material. Here we recount\nnew observations at short times, in the single bead system, in cement paste and\nin sandstone and mortar. Notwithstanding the limits imposed by finite duration\nring down such that the effective instant of conditioning cessation is\nimprecise, and the corresponding ambiguity as to the time that relaxation\nbegins, we find no reliable sign of such a transition, even in samples of large\ngrain size mortar similar to those described elsewhere as having clear and late\ncutoffs."
    },
    {
        "anchor": "Curvature effects in charge-regulated lipid bilayers: We formulate a theory of electrostatic interactions in lipid bilayer\nmembranes where both monolayer leaflets contain dissociable moieties that are\nsubject to charge regulation. We specifically investigate the coupling between\nmembrane curvature and charge regulation of a lipid bilayer vesicle using both\nthe linear Debye-H\\\"uckel (DH) and the non-linear Poisson-Boltzmann (PB)\ntheory. We find that charge regulation of an otherwise symmetric bilayer\nmembrane can induce charge symmetry breaking, non-linear flexoelectricity and\nanomalous curvature dependence of free energy. The pH effects investigated go\nbeyond the paradigm of electrostatic renormalization of the mechano-elastic\nproperties of membranes.",
        "positive": "Critical Exponents for Granular Phase Transitions: The solid--fluid phase transition of a granular material shaken horizontally\nis investigated numerically. We find that it is a second-order phase transition\nand propose two order parameters, namely the averaged kinetic energy and the\naveraged granular temperature, to determine the fluidization point precisely.\nIt scales with the acceleration of the external vibration. Using this\nfluidization point as critical point, we discuss the scaling of the kinetic\nenergy and show that the kinetic energy and the granular temperature show two\ndifferent universal critical point exponents for a wide range of excitation\namplitudes."
    },
    {
        "anchor": "Driving Bose-Einstein condensate vorticity with a rotating normal cloud: We have developed an evaporative cooling technique that accelerates the\ncirculation of an ultra-cold $^{87}$Rb gas, confined in a static harmonic\npotential. As a normal gas is evaporatively spun up and cooled below quantum\ndegeneracy, it is found to nucleate vorticity in a Bose-Einstein condensate.\nMeasurements of the condensate's aspect ratio and surface-wave excitations are\nconsistent with effective rigid-body rotation. Rotation rates of up to 94% of\nthe centrifugal limit are inferred. A threshold in the normal cloud's rotation\nis observed for the intrinsic nucleation of the first vortex. The threshold\nvalue lies below the prediction for a nucleation mechanism involving the\nexcitation of surface-waves of the ground-state condensate.",
        "positive": "Regelation: why does ice melt under pressure?: Unlike other unusual materials whose bonds contract under compression, the\nO:H nonbond undergoes contraction and the H-O bond elongation towards O:H and\nH-O length symmetry in water and ice. The energy drop of the H-O bond dictates\nthe melting point Tm depression of ice. Once the pressure is relieved, the\nO:H-O bond fully recovers its initial state, resulting in Regelation."
    },
    {
        "anchor": "Structural Transition in the Isotropic Phase of the\n  C$_{12}$EO$_6$/H$_2$O Lyotropic Mixture: A Rheological Investigation: We study the structural changes occurring in the isotropic phase of the\nC$_{12}$=EO$_6$/H$_2$O lyotropic mixture (up to 35% surfactant weight\nconcentration) upon increasing the concentration and temperature, from small\nindividual micelles to an entangled network which subsequently becomes\nconnected. High-frequency (up to $\\omega = 6 \\times 10^4$ rad/s) rheological\nmeasurements give us access to the viscoelastic relaxation spectrum, which can\nbe well described by the sum of two Maxwell models with very different\ntemperature behaviors: the slower one ($\\tau _1 \\simeq 10^{-4}$ s) is probably\ndue to reptation, and its associated viscosity first increases with temperature\n(micellar growth) and then decreases after reaching a maximum (appearance of\nconnections). The fast mechanism ($\\tau _2 \\simeq 10^{-6}$ s) remains\npractically unchanged in temperature and can be related to the relaxation of\nlocal micellar order, as observed at higher concentration in a previous\ninvestigation. This interpretation is confirmed by additional measurements in\naqueous mixtures of the related surfactant C$_{12}$EO$_8$ (which forms smaller\nmicelles), where only the fast mechanism -related to local order- is detected.",
        "positive": "Scaling of the dynamics of flexible Lennard-Jones chains: The isomorph theory provides an explanation for the so-called power law\ndensity scaling which has been observed in many molecular and polymeric glass\nformers, both experimentally and in simulations. Power law density scaling\n(relaxation times and transport coefficients being functions of\n$\\rho^{\\gamma_S}/T$, where $\\rho$ is density, $T$ is temperature, and\n$\\gamma_S$ is a material specific scaling exponent) is an approximation to a\nmore general scaling predicted by the isomorph theory. Furthermore, the\nisomorph theory provides an explanation for Rosenfeld scaling (relaxation times\nand transport coefficients being functions of excess entropy) which has been\nobserved in simulations of both molecular and polymeric systems. Doing\nmolecular dynamics simulations of flexible Lennard-Jones chains (LJC) with\nrigid bonds, we here provide the first detailed test of the isomorph theory\napplied to flexible chain molecules. We confirm the existence of isomorphs,\nwhich are curves in the phase diagram along which the dynamics is invariant in\nthe appropriate reduced units. This holds not only for the relaxation times but\nalso for the full time dependence of the dynamics, including chain specific\ndynamics such as the end-to-end vector autocorrelation function and the\nrelaxation of the Rouse modes. As predicted by the isomorph theory, jumps\nbetween different state points on the same isomorph happen instantaneously\nwithout any slow relaxation. Since the LJC is a simple coarse-grained model for\nalkanes and polymers, our results provide a possible explanation for why\npower-law density scaling is observed experimentally in alkanes and many\npolymeric systems. The theory provides an independent method of determining the\nscaling exponent, which is usually treated as a empirical scaling parameter."
    },
    {
        "anchor": "Crossover from Shear-Driven to Thermally Activated Drainage of\n  Liquid-Infused Microscale Capillaries: The shear-driven drainage of capillary grooves filled with viscous liquid is\na dynamic wetting phenomenon relevant to numerous industrial processes and\nnovel lubricant-infused surfaces. Prior work has reported that a finite length\n$L_\\infty$ of the capillary groove can remain indefinitely filled with liquid\neven when large shear stresses are applied. The mechanism preventing full\ndrainage is attributed to a balance between the shear-driven flow and a\ncounterflow driven by capillary pressures caused by deformation of the free\nsurface. The final equilibrium length $L_\\infty$ is uniquely determined by\nphysical properties of the filling liquid as well as the geometry and\nwettability of the capillary. In this work, we examine closely the approach to\nthe final equilibrium length $L_\\infty$ and report a crossover to a slow\ndrainage regime that cannot be described by conventional dynamic models\nconsidering solely hydrodynamic and capillary forces. The slow drainage regime\nobserved in experiments can be instead modeled by a kinetic equation describing\na sequence of random thermally activated transitions between multiple\nmetastable states caused by surface defects with nanoscale dimensions. Our\nfindings provide new insights on the critical role that natural or engineered\nsurface roughness with nanoscale dimensions can play in the imbibition and\ndrainage of capillaries and other dynamic wetting processes in microscale\nsystems.",
        "positive": "Molecular Weight Dependence of Excluded Volume Effects: Molecular weight dependence of excluded volume effects is examined. The\nswollen-to-unperturbed coil transition point shifts to lower concentration\nrange with increasing molecular weight (Mw). It is shown that in the limit of\nthe infinite molecular weight, the excluded volume effects should vanish in all\nconcentration range, except for the only one point, Co = 0. Quite in contrast,\nfor short chains, the excluded volume effects never disappear even at the melt\nstate."
    },
    {
        "anchor": "Continuum Theory of Polymer Crystallization: We present a kinetic model of crystal growth of polymers of finite molecular\nweight. Experiments help to classify polymer crystallization broadly into two\nkinetic regimes. One is observed in melts or in high molar mass polymer\nsolutions and is dominated by nucleation control with $G \\sim \\exp(1/T \\Delta\nT)$, where $G$ is the growth rate and $\\Delta T$ is the super-cooling. The\nother is observed in low molar mass solutions (as well as for small molecules)\nand is diffusion controlled with $G \\sim \\Delta T$, for small $\\Delta T$. Our\nmodel unifies these two regimes in a single formalism. The model accounts for\nthe accumulation of polymer chains near the growth front and invokes an\nentropic barrier theory to recover both limits of nucleation and diffusion\ncontrol. The basic theory applies to both melts and solutions, and we\nnumerically calculate the growth details of a single crystal in a dilute\nsolution. The effects of molecular weight and concentration are also determined\nconsidering conventional polymer dynamics. Our theory shows that entropic\nconsiderations, in addition to the traditional energetic arguments, can capture\ngeneral trends of a vast range of phenomenology. Unifying ideas on\ncrystallization from small molecules and from flexible polymer chains emerge\nfrom our theory.",
        "positive": "Boundary Condition of Polyelectrolyte Adsorption: The modification of the boundary condition for polyelectrolyte adsorption on\ncharged surface with short-ranged interaction is investigated under two\nregimes. For weakly charged Gaussian polymer in which the short-ranged\nattraction dominates, the boundary condition is the same as that of the neutral\npolymer adsorption. For highly charged polymer (compressed state) in which the\nelectrostatic interaction dominates, the linear relationship (electrostatic\nboundary condition) between the surface monomer density and the surface charge\ndensity needs to be modified."
    },
    {
        "anchor": "Local dielectric spectroscopy of near-surface glassy polymer dynamics: A non-contact scanning-probe-microscopy method was used to probe local\nnear-surface dielectric susceptibility and dielectric relaxation in\npoly-vinyl-acetate (PVAc) near the glass transition. Dielectric spectra were\nmeasured from 10-4 Hz to 102 Hz as a function of temperature. The measurements\nprobed a 20 nm thick layer below the free-surface of a bulk film. A small (4 K)\nreduction in glass transition temperature and moderate narrowing of the\ndistribution of relaxation times was found. In contrast to results for\nultra-thin-films confined on or between metallic electrodes, no reduction in\nthe dielectric strength was found, inconsistent with the immobilization of\nslower modes.",
        "positive": "Ultrasonic study of the gelation of gelatin: phase diagram, hysteresis\n  and kinetics: We map the ultrasonic (8 MHz) speed and attenuation of edible-grade gelatin\nin water, exploring the key dependencies on temperature, concentration and\ntime. The ultrasonic signatures of the sol-gel transition, confirmed by\nrheological measurements, and incomplete gel formation at low concentrations,\nenable a phase diagram of the system to be constructed. Sensitivity is also\ndemonstrated to the kinetics of gel formation and melting, and associated\nhysteresis effects upon cyclic temperature sweeps. Furthermore, simple acoustic\nmodels of the sol and gel state enable estimation of the speed of sound and\ncompressibility of gelatin. Our results demonstrate the potential of ultrasonic\nmeasurements to characterise the structure and visco-elasticity of gelatin\nhydrogels."
    },
    {
        "anchor": "Driven and undriven states of multicomponent granular gases of inelastic\n  and rough hard disks or spheres: Starting from a recent derivation of the energy production rates in terms of\nthe number of translational and rotational degrees of freedom, a comparative\nstudy on different granular temperatures in gas mixtures of inelastic and rough\ndisks or spheres is carried out. Both the homogeneous freely cooling state and\nthe state driven by a stochastic thermostat are considered. It is found that\nthe relaxation number of collisions per particle is generally smaller for disks\nthan for spheres, the mean angular velocity relaxing more rapidly than the\ntemperature ratios. In the asymptotic regime of the undriven system, the\nrotational-translational nonequipartition is stronger in disks than in spheres,\nwhile it is hardly dependent on the class of particles in the driven system. On\nthe other hand, the degree of component-component nonequipartition is higher\nfor spheres than for disks, both for driven and undriven systems. A study of\nthe mimicry effect (whereby a multicomponent gas mimics the\nrotational-translational temperature ratio of a monocomponent gas) is also\nundertaken.",
        "positive": "Active turbulence in microswimmer suspensions -- the role of active\n  hydrodynamic stress and volume exclusion: Microswimmers exhibit an intriguing, highly-dynamic collective motion with\nlarge-scale swirling and streaming patterns, denoted as active turbulence --\nreminiscent of classical high-Reynolds-number hydrodynamic turbulence. Various\nexperimental, numerical, and theoretical approaches have been applied to\nelucidate similarities and differences to inertial hydrodynamic and active\nturbulence. These studies reveal a wide spectrum of possible structural and\ndynamical behaviors of active mesoscale systems, not necessarily consistent\nwith the predictions of the Kolmogorov-Kraichnan theory of turbulence. We use\nsquirmers embedded in a mesoscale fluid, modeled by the multiparticle collision\ndynamics (MPC) approach, to explore the collective behavior of bacteria-type\nmicroswimmers. Our model includes the active hydrodynamic stress generated by\npropulsion, and a rotlet dipole characteristic for flagellated bacteria. We\nfind emergent clusters, activity-induced phase separation, and swarming,\ndepending on density, active stress, and the rotlet dipole strength. The\nanalysis of the squirmer dynamics in the swarming phase yields\nKolomogorov-Kraichnan-type hydrodynamic turbulence and energy spectra for\nsufficiently high concentrations and strong rotlet dipoles. This emphasizes the\nparamount importance of the hydrodynamic flow field for swarming and bacterial\nturbulence."
    },
    {
        "anchor": "Testing a New Monte Carlo Strategy for Folding Model Proteins: We demonstrate that the recently proposed pruned-enriched Rosenbluth method\nPERM (P.~Grassberger, Phys.~Rev.~{\\bf E 56} (1997)\n  3682) leads to very efficient algorithms for the folding of simple model\nproteins. We test it on several models for lattice heteropolymers, and compare\nto published Monte Carlo studies of the properties of particular sequences. In\nall cases our method is faster than the previous ones, and in several cases we\nfind new minimal energy states. In addition to producing more reliable\ncandidates for ground states, our method gives detailed information about the\nthermal spectrum and, thus, allows to analyze static aspects of the folding\nbehavior of arbitrary sequences.",
        "positive": "Dynamics of 2D Monolayer Confined Water in Hydrophobic and Charged\n  Environments: Using molecular dynamics simulations we study the dynamics of a water-like\nTIP5P model of water in hydrophilic and hydrophobic confinement. We find that\nin case of extreme nanocofinement such that there is only one molecular layer\nof water between the confinement surface, the dynamics of water remains\nArrhenius with a very high activation energy up to high temperatures. In case\nof polar (hydrophilic) confinement, The intermediate time scale dynamics of\nwater is drastically modified presumably due to the transient coupling of\ndipoles with the effective electric field due to the surface charges.\nSpecifically, we find that in the presence of the polar surfaces, the dynamics\nof monolayer water shows anomalous region -- namely the lateral mean square\ndisplacement displays a distinct superdiffusive intermediate time scale\nbehavior in addition to ballistic and diffusive regimes. We explain these\nfinding by proposing a simple model. Furthermore, we find that confinement and\nthe surface polarity changes the vibrational density of states specifically we\nsee the enhancement of the low frequency collective modes in confinement\ncompared to bulk water. Finally, we find that the length scale of\ntranslational-orientational coupling increases with the strength of the\npolarity of the surface."
    },
    {
        "anchor": "Elastic properties of vanadium pentoxide aggregates and topological\n  defects: We study the aqueous solution of vanadium pentoxide by using topology\nmethods. The experiments by Zocher, Kaznacheev, and Dogic exhibited, that in\nthe sol phases of $V_2O_5-H_2O$, the tactoid droplets of $V_2O_5$ can coalesce.\nIn the magnetic field, this effect is associated with a gauge field action,\nviz. we consider coalescence (in the topologically more convenient term,\n\"junction\") of droplets as annihilation of topological defects, concerning with\nthe tactoid geometry. We have shown, that in the magnetic field, the tactoid\njunction is mainly caused by non-Abelian monopoles (vortons), whereas the\nAbelian defects almost do not annihilate. Taking into account this annihilation\nmechanism, the estimations of time-aging of the $V_2O_5-H_2O$ sols may be\nspecified",
        "positive": "Excess entropy, Diffusivity and Structural Order in liquids with\n  water-like anomalies: The excess entropy, Se, defined as the difference between the entropies of\nthe liquid and the ideal gas under identical density and temperature\nconditions, is shown to be the critical quantity connecting the structural,\ndiffusional and density anomalies in water-like liquids. Based on simulations\nof silica and the two-scale ramp liquids, water-like density and diffusional\nanomalies can be seen as consequences of a characteristic non-monotonic density\ndependence of Se. The relationship between excess entropy, the order metrics\nand the structural anomaly can be understood using a pair correlation\napproximation to Se."
    },
    {
        "anchor": "In Situ Ion Induced Gelation of Colloidal Dispersion of Laponite:\n  Relating Microscopic Interactions to Macroscopic Behavior: Aqueous dispersion of Laponite, when exposed to carbon dioxide environment\nleads to in situ inducement of magnesium and lithium ions, which is, however\nabsent when dispersion is exposed to air. Consequently, in the rheological\nexperiments, Laponite dispersion preserved under carbon dioxide shows more\nspectacular enhancement in the elastic and viscous moduli as a function of time\ncompared to that exposed to air. By measuring concentration of all the ions\npresent in a dispersion as well as change in pH, the evolving inter-particle\ninteractions among the Laponite particles is estimated. DLVO analysis of a\nlimiting case is performed, wherein two particles approach each other in a\nparallel fashion a situation with maximum repulsive interactions. Interestingly\nit is observed that DLVO analysis explains the qualitative details of an\nevolution of elastic and viscous moduli remarkably well thereby successfully\nrelating the macroscopic phenomena to the microscopic interactions.",
        "positive": "Chirality for crooked curves: Chiral objects rotate when placed in a collimated flow or wind. We exploit\nthis hydrodynamic intuition to construct a tensorial chirality measure for\nrigid filaments and curves. This tensor is trace-free, so if a curve has a\nright-handed twist about some axis, there is a perpendicular axis about which\nthe twist is left-handed. Our measure places minimal requirements on the\nsmoothness of the curve, hence it can be readily used to quantify chirality for\nbiomolecules and polymers, polygonal and rectifiable curves, and other discrete\ngeometrical structures."
    },
    {
        "anchor": "Molecular Dynamics Simulation of Apolipoprotein E3 Lipid Nanodiscs: Nanodiscs are binary discoidal complexes of a phospholipid bilayer\ncircumscribed by belt-like helical scaffold proteins. Using coarse-grained and\nall-atom molecular dynamics simulations, we explore the stability, size, and\nstructure of nanodiscs formed between the N-terminal domain of apolipoprotein\nE3 (apoE3-NT) and variable number of\n1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) molecules. We study both\nparallel and antiparallel double-belt configurations, consisting of four\nproteins per nanodisc. Our simulations predict nanodiscs containing between 240\nand 420 DMPC molecules to be stable. The antiparallel configurations exhibit an\naverage of 1.6 times more amino acid interactions between protein chains and 2\ntimes more ionic contacts, compared to the parallel configuration. With one\nexception, DMPC order parameters are consistently larger in the antiparallel\nconfiguration than in the parallel one. In most cases, the root mean square\ndeviation of the positions of the protein backbone atoms is smaller in the\nantiparallel configuration. We further report nanodisc size, thickness, radius\nof gyration, and solvent accessible surface area. Combining all investigated\nparameters, we hypothesize the antiparallel protein configuration leading to\nmore stable and more rigid nanodiscs than the parallel one.",
        "positive": "Elastic deformation during dynamic force measurements in viscous fluids: Understanding and harnessing the coupling between lubrication pressure and\nelasticity provides materials design strategies for applications such as\nadhesives, coatings, microsensors, and biomaterials. Elastic deformation of\ncompliant solids caused by viscous forces can also occur during dynamic force\nmeasurements in instruments such as the surface forces apparatus (SFA) or the\natomic force microscope (AFM). We briefly review hydrodynamic interactions in\nthe presence of soft, deformable interfaces in the lubrication limit. More\nspecifically, we consider the scenario of two surfaces approaching each other\nin a viscous fluid where one or both surfaces is deformable, which is also\nrelevant to many force measurement systems. In this article the basic\ntheoretical background of the elastohydrodynamic problem is detailed, followed\nby a discussion of experimental validation and considerations, especially for\nthe role of elastic deformation on surface forces measurements. Finally,\ncurrent challenges to our understanding of soft hydrodynamic interactions, such\nas the consideration of substrate layering, poroelasticity, viscoelasticity,\nsurface heterogeneity, as well as their implications are discussed."
    },
    {
        "anchor": "Shear flow induced isotropic to nematic transition in a suspension of\n  active filaments: We study the effects of externally applied shear flow on a model of\nsuspensions of motors and filaments, via the equations of active hydrodynamics\n[PRL {\\bf 89} (2002) 058101; {\\bf 92} (2004) 118101]. In the absence of shear,\nthe orientationally ordered phase of {\\it both} polar and apolar active\nparticles is always unstable at zero-wavenumber. An imposed steady shear large\nenough to overcome the active stresses stabilises both apolar and moving polar\nphases. Our work is relevant to {\\it in vitro} studies of active filaments, the\nreorientation of endothelial cells subject to shear flow and shear-induced\nmotility of attached cells.",
        "positive": "Phase nucleation in curved space: Nucleation and growth is the dominant relaxation mechanism driving first\norder phase transitions. In two-dimensional at systems nucleation has been\napplied to a wide range of problems in physics, chemistry and biology. Here we\nstudy nucleation and growth of two-dimensional phases lying on curved surfaces\nand show that curvature modify both, critical sizes of nuclei and paths towards\nthe equilibrium phase. In curved space nucleation and growth becomes inherently\ninhomogeneous and critical nuclei form faster on regions of positive Gaussian\ncurvature. Substrates of varying shape display complex energy landscapes with\nseveral geometry-induced local minima, where initially propagating nuclei\nbecome stabilized and trapped by the underlying curvature."
    },
    {
        "anchor": "Friction and Memory Effects in Homogeneous Gas-Liquid Nucleation: Quest\n  for Quantitative Rate Calculation: The task of a first principles theoretical calculation of the rate of gas to\nliquid nucleation has remained largely incomplete despite the existence of\nreliable results from unbiased simulation studies at large supersaturation.\nAlthough the classical nucleation theory, formulated by Becker-Doring-Zeldovich\n(BDZ) about a century ago, provides an elegant, widely-used picture of\nnucleation in a first-order phase transition, the theory finds difficulties in\npredicting the rate accurately, especially in the case of gas-to-liquid\nnucleation. Here, we use a multiple-order parameter description to construct\nthe nucleation free energy surface needed to calculate the nucleation rate. A\nmultidimensional non-Markovian rate theory formulation that generalizes\nLanger's well-known nucleation theory by using Grote-Hynes multidimensional\nnon-Markovian treatment is used to obtain the rate of barrier crossing. We find\ngood agreement of the theory with the rate obtained by direct unbiased\nmolecular dynamics simulations, the latter is feasible at large\nsupersaturation, S. The theory gives the experimentally strong dependence of\nthe rate of nucleation on supersaturation, S. Interestingly, we find a strong\ninfluence of frequency-dependent friction at the barrier top. This arises from\nmultiple recrossing of the barrier surface. We find that a Markovian theory,\nsuch as Langer's formulation, fails to capture the rate quantitatively. In\naddition, the multidimensional transition state theory expression performs\npoorly, revealing the underlying role of friction.",
        "positive": "Cooperative Motions and Topology-Driven Dynamical Arrest in Prime Knots: Knots are entangled structures that cannot be untangled without a cut.\nTopological stability of knots is one of the many examples of their important\nproperties that can be used in information storage and transfer. Knot dynamics\nis important for understanding general principles of entanglement as knots\nprovide an isolated system where tangles are highly controlled and easily\nmanipulated. To unravel the dynamics of these entangled topological objects,\nthe first step is to identify the dominant motions that are uniquely guided by\nknot structure and its complexity. We identify and classify motions into three\nmain groups -- orthogonal, aligned, and mixed motions, which often act in\nunison, orchestrating the complex dynamics of knots. The balance between these\nmotions is what creates an identifiable signature for every knot. As knot\ncomplexity increases, the carefully orchestrated dynamics is gradually\nsilenced, eventually reaching a state of topologically driven dynamical arrest.\nDepending on their complexity, knots undergo a transition from nearly\nstochastic motions to either non-random or even quasiperiodic dynamics before\nculminating in dynamical arrest. Here, we show for the first time that\nconnectivity alone can lead to a topology-driven dynamical arrest in knots of\nhigh complexity. Unexpectedly, we noticed that some knots undergo cooperative\nmotions as they reach higher complexity, uniquely modulating conformational\npatterns of a given knot. Together, these findings demonstrate a link between\ntopology and dynamics, presenting applications to nanoscale materials."
    },
    {
        "anchor": "Self-Starting Micromotors in a Bacterial Bath: Micromotors pushed by biological entities, like motile bacteria, constitute a\nfascinating way to convert chemical energy into mechanical work at the\nmicrometer scale. Here we show, by using numerical simulations, that a properly\ndesigned asymmetric object can be spontaneously set into the desired motion\nwhen immersed in a chaotic bacterial bath. Our findings open the way to\nconceive new hybrid microdevices exploiting the mechanical power production of\nbacterial organisms. Moreover, the system provides an example of how, in\ncontrast with equilibrium thermal baths, the irreversible chaotic motion of\nactive particles can be rectified by asymmetric environments.",
        "positive": "Bistable Auxetic Mechanical Metamaterials Inspired by Ancient Geometric\n  Motifs: Auxetic materials become thicker rather than thinner when stretched,\nexhibiting an unusual negative Poisson's ratio well suited for designing shape\ntransforming metamaterials. Current auxetic designs, however, are often\nmonostable and cannot maintain the transformed shape upon load removal. Here,\ninspired by ancient geometric motifs arranged in square and triangular grids,\nwe introduce a class of switchable architected materials exhibiting\nsimultaneous auxeticity and structural bistability. The material concept is\nexperimentally realized by perforating various cut motifs into a sheet of\nrubber, thus creating a network of rotating units connected with compliant\nhinges. The metamaterial performance is assessed through mechanical testing and\naccurately predicted by a coherent set of finite element simulations. A\ndiscussion on a rich set of mechanical phenomena follows to shed light on the\nmain design principles governing bistable auxetics."
    },
    {
        "anchor": "Electric field shielding in dielectric nanosolutions: To gain some insight into electrochemical activity of dielectric colloids of\ntechnical and biomedical interest we investigate a model of dielectric\nnanosolution whose micro-constitution is dominated by dipolarions -- positively\nand negatively charged spherically symmetric nano-structures composed of ionic\ncharge surrounded by cloud of radially polarized dipoles of electrically\nneutral molecules of solvent. Combing the standard constitutive equations of an\nisotropic dielectric liquid with Maxwell equation of electrostatics and\npresuming the Boltzmann shape of the particle density of bound-charge we derive\nequation for the in-medium electrostatic field. Particular attention is given\nto numerical analysis of obtained analytic solutions of this equation\ndescribing the exterior fields of dipolarions with dipolar atmospheres of\nsolvent molecules endowed with either permanent or field-induced dipole moments\nradially polarized by central symmetric field of counterions. The presented\ncomputations show that the electric field shielding of dipolarions in\ndielectric nanosolutions is quite different from that of counterionic\nnano-complexes of Debye-H\\\"uckel theory of electrolytes.",
        "positive": "Freezing and correlations in fluids with competing interactions: We consider fluids where the attractive interaction at distances slightly\nlarger than the particle size is dominated at larger distances by a repulsive\ncontribution. A previous investigation of the effects of the competition\nbetween attraction and repulsion on the liquid-vapour transition and on the\ncorrelations is extended to the study of the stability of liquid-vapour phase\nseparation with respect to freezing. We find that this long-range repulsive\npart of the interaction expands the region where the fluid-solid transition\npreempts the liquid-vapour one, so that the critical point becomes metastable\nat longer attraction ranges than those required for purely attractive\npotentials. Moreover, the large density fluctuations that occur near the\nliquid-vapour critical point are greatly enhanced by the competition between\nattractive and repulsive forces, and encompass a much wider region than in the\nattractive case. The decay of correlations for states where the compressibility\nis large is governed by two characteristic lengths, and the usual\nOrnstein-Zernike picture breaks down except for the very neighborhood of the\ncritical point, where one length reduces to the commonly adopted correlation\nlength, while the other one saturates at a finite value."
    },
    {
        "anchor": "Statistical mechanics of a polymer chain attached to the interface of a\n  cone-shaped channel: A polymer chain confined in nano-scale geometry has been used to investigate\nthe underlying mechanism of Nuclear Pore Complex (NPC), where transport of\ncargoes is directional. It was shown here that depending on the solvent quality\n(good or poor) across the channel, a polymer chain can be either inside or\noutside the channel or both. Exact results based on the short chain revealed\nthat a slight variation in the solvent quality can drag polymer chain inside\nthe pore and {\\it vice versa} similar to one seen in NPC. Furthermore, we also\nreport the absence of crystalline (highly dense) state when the pore-size is\nless than the certain value, which may have potential application in packaging\nof DNA inside the preformed viral proheads.",
        "positive": "Some Thermodynamic Properties of Colloidal Dispersions: In this paper, some equations are derived to describe the out-of-equilibrium\nthermodynamics of colloidal suspensions. These results are obtained assuming\nthat the properties of the colloids essentially come from their surfaces which\nare unusually high in comparison to their volume. The dispersion, in the form\nof a variable, is introduced in such a way as to embody the various changes\nwhich could affect those systems. Explicit relations are deduced for the free\nenthalpy of dispersion which describe two separated phenomena: the\npeptization/coalescence and the suspension of a colloidal phase."
    },
    {
        "anchor": "The Role of Molecular Quantum Electrodynamics in Linear Aggregations of\n  Red Blood Cells: Despite the fact that red blood cells carry negative charges, under certain\nconditions they form cylindrical stacks, or ``rouleaux''. It is shown here that\na form of the Casimir effect, generalizing the more well-known van der Waals\nforces, can provide the necessary attractive force to balance the electrostatic\nrepulsion. Erythrocytes in plasma are modelled as negatively charged dielectric\ndisks in an ionic solution, allowing predictions to be made about the\nconditions under which rouleaux will form. The results show qualitative and\nquantitative agreement with observations, and suggest new experiments and\nfurther applications to other biological systems, colloid chemistry and\nnanotechnology.",
        "positive": "Fractal approach to the beta relaxation in supercooled liquids: In the present work we present a fractal model for the beta relaxation in\nsupercooled liquids. The macroscopic dynamics is obtained by superposition of\nrelaxation of independent mesoscopic regions (cages). Scaling relations and\nexponents are assumed for the distribution of cage sizes and for the size\ndependent response of the independent cages. In this way we obtain some scaling\nrelations for the average response, in the time and frequency domain. For a\nparticular choice of the scaling exponents we obtain the scaling relations\npredicted by the MCT. The comparison with recent light scattering data reveals\nthat the scaling exponents of the distribution of cage sizes are universal but\nthe single cage relaxation depends on the detailed material structure"
    },
    {
        "anchor": "Hydrodynamic slip boundary condition at chemically patterned surfaces: A\n  continuum deduction from molecular dynamics: We investigate the slip boundary condition for single-phase flow past a\nchemically patterned surface. Molecular dynamics (MD) simulations show that\nmodulation of fluid-solid interaction along a chemically patterned surface\ninduces a lateral structure in the fluid molecular organization near the\nsurface. Consequently, various forces and stresses in the fluid vary along the\npatterned surface. Given the presence of these lateral variations, a general\nscheme is developed to extract hydrodynamic information from MD data. With the\nhelp of this scheme, the validity of the Navier slip boundary condition is\nverified for the chemically patterned surface, where a local slip length can be\ndefined. Based on the MD results, a continuum hydrodynamic model is formulated\nusing the Navier-Stokes equation and the Navier boundary condition, with a slip\nlength varying along the patterned surface. Steady-state velocity fields from\ncontinuum calculations are in quantitative agreement with those from MD\nsimulations. It is shown that, when the pattern period is sufficiently small,\nthe solid surface appears to be homogeneous, with an effective slip length that\ncan be controlled by surface patterning. Such a tunable slip length may have\nimportant applications in nanofluidics.",
        "positive": "Formation of double glass in binary mixtures of anisotropic particles: We study glass transitions in mixtures of elliptic and circular particles in\ntwo dimensions using an orientation-dependent Lennard-Jones potential. Changing\nanisotropic parameters of the potential, the size ratio, and the concentration,\nwe realize double glass, where both the particle positions and orientations are\ndisordered but still hold mesoscopic order. The ellipses are anchored around\nthe circular impurities in the homeotropic or planar directions. We examine\nslowing-down of rotational and translational time-correlation functions.\nTurnover motions of the ellipses are activated more frequently than the\nconfiguration changes, where the latter cause the structural relaxation."
    },
    {
        "anchor": "First principles determination of some static and dynamic properties of\n  the liquid 3$d$ transition metals near melting: We report an ab initio molecular dynamics simulation study of several static\nand dynamic properties of the liquid 3d transition metals. The calculated\nstatic structure factors show qualitative agreement with the available\nexperimental data, and its second peak displays an asymmetric shape which\nsuggests a significant local icosahedral short-range order. The dynamical\nstructure reveals propagating density fluctuations whose dispersion relation\nhas been evaluated; moreover, its long wavelength limit is compatible with\ntheir respective experimental sound velocity. Results are reported for the\nlongitudinal and transverse current spectral functions as well as for the\nrespective dispersion relations. We also analyze the possible appearance of\ntransverse-like low-energy excitations in the calculated dynamic structure\nfactors. Several transport coefficients have been evaluated and compared with\nthe available experimental data.",
        "positive": "Topological boundary modes in jammed matter: Granular matter at the jamming transition is poised on the brink of\nmechanical stability, and hence it is possible that these random systems have\ntopologically protected surface phonons. Studying two model systems for jammed\nmatter, we find states that exhibit distinct mechanical topological classes,\nprotected surface modes, and ubiquitous Weyl points. The detailed statistics of\nthe boundary modes enable tests of a standard understanding of the detailed\nfeatures of the jamming transition, and show that parts of this argument are\ninvalid."
    },
    {
        "anchor": "Fracturing of topological Maxwell lattices: We present fracturing analysis of topological Maxwell lattices when they are\nstretched by applied stress. Maxwell lattices are mechanical structures\ncontaining equal numbers of degrees of freedom and constraints in the bulk and\nare thus on the verge of mechanical instability. Recent progress in topological\nmechanics led to the discovery of topologically protected floppy modes and\nstates of self stress at edges and domain walls of Maxwell lattices. When\nnormal brittle materials are being stretched, stress focuses on crack tips,\nleading to catastrophic failure. In contrast, we find that when topological\nMaxwell lattices are being stretched, stress focuses on states of self stress\ndomain walls instead, and bond-breaking events start at these domain walls,\neven in presence of cracks. Remarkably, we find that the stress-focusing\nfeature of the self-stress domain walls persists deep into the the failure\nprocess, when a lot of damages already occurred at these domain walls. We\nexplain the results using topological mechanics theory and discuss the\npotential use of these topological Maxwell lattice structures as mechanical\nmetamaterials that exhibit high strength against fracturing and well controlled\nfracturing process.",
        "positive": "A method for estimating the interactions in dissipative particle\n  dynamics from particle trajectories: We introduce a method for determining the functional form of the stochastic\nand dissipative interactions in a dissipative particle dynamics (DPD) model\nfrom projected phase space trajectories. The DPD model is viewed as a coarse\ngraining of a detailed dynamics that displays a clear time scale separation.\nBased on the Mori-Zwanzig projection operator method we derive a consistency\nequation for the stochastic interaction in DPD. The consistency equation can be\nsolved by an iterative boot strapping procedure. Combined with standard\ntechniques for estimating the conservative interaction, our method makes it\npossible to reconstruct all the forces in a coarse grained DPD model. We\ndemonstrate how the method works by recreating the interactions in a DPD model\nfrom its phase space trajectory. Furthermore, we discuss how our method can be\nused in realistic systems with finite time scale separation."
    },
    {
        "anchor": "PECVD and PEALD on polymer substrates (Part II): Understanding and\n  tuning of barrier and membrane properties of thin films: This feature article presents insights concerning the correlation of PECVD\nand PEALD thin film structures with their barrier or membrane properties. While\nin principle similar precursor gases and processes can be applied, the\nadjustment of deposition parameters for different polymer substrates can lead\nto either an effective diffusion barrier or selective permeabilities. In both\ncases the understanding of the film growth and the analysis of the pore size\ndistribution and the pore surface chemistry is of utmost importance for the\nunderstanding of the related transport properties of small molecules. In this\nregard the article presents both concepts of thin film engineering and\nanalytical as well as theoretical approaches leading to a comprehensive\ndescription of the state of the art in this field. Moreover, based on the\npresented correlation of film structure and molecular transport properties\nperspectives of future relevant research in this area is presented.",
        "positive": "Foams Stabilized by Tricationic Amphiphilic Surfactants: The unique surface properties of amphiphilic molecules have made them widely\nused in applications where foaming, emulsifying or coating processes are\nneeded. Novel surfactant architectures with multi-cephalic and multi-tailed\nmolecules have reportedly enhanced their anti-bacterial activity in connection\nwith tail length and the nature of the head group, but their ability to produce\nand stabilize foam is mostly unknown. Here we report on experiments with\ntris-cationic, triple-headed, double- and single-tailed amphiphiles and their\nfoamability and foam stability with respect to head group, tail number and tail\nlength. The amphiphiles are composed of an aromatic mesitylene core and three\nbenzylic amonium bromide groups, with alkyl chains attached to one or two of\nthe head groups. Whereas shorter (14 carbons in length) double-tailed molecules\nare found to produce very stable foams, foams made with single tail molecules\nof the same length show poor foamability and stability, and foams with longer\n(16 carbons in length) double-tail molecules do not foam with the methods used.\nBy contrast, the structure of the non-tail-bearing head group\n(trimethylammonium vs. pyridinium) has no impact on foamability. Furthermore,\nobservations of the coarsening rate at nearly constant liquid content indicate\nthat the enhanced foam stability is a result of lower gas permeability through\nthe surfactant monolayer. Finally, the critical aggregation concentration (CAC)\nof the surfactants demonstrates to be a good predictor of foamability and foam\nstability for these small molecule surfactants. This results inform how\nsurfactant architecture can be tailored to produce stable foams."
    },
    {
        "anchor": "Observations on Sound Propagation in Rapidly Rotating Bose-Einstein\n  Condensates: Repulsive laser potential pulses applied to vortex lattices of rapidly\nrotating Bose-Einstein condensates create propagating density waves which we\nhave observed experimentally and modeled computationally to high accuracy. We\nhave observed a rich variety of dynamical phenomena ranging from interference\neffects and shock-wave formation to anisotropic sound propagation.",
        "positive": "Compressive force generation by a bundle of living biofilaments: To study the compressional forces exerted by a bundle of living stiff\nfilaments pressing on a surface, akin to the case of an actin bundle in\nfilopodia structures, we have performed particulate Molecular Dynamics\nsimulations of a grafted bundle of parallel living (self-assembling) filaments,\nin chemical equilibrium with a solution of their constitutive monomers.\nEquilibrium is established as these filaments, grafted at one end to a wall of\nthe simulation box, grow at their chemically active free end and encounter the\nopposite confining wall of the simulation box. Further growth of filaments\nrequires bending and thus energy, which automatically limit the populations of\nlonger filaments. The resulting filament sizes distribution and the force\nexerted by the bundle on the obstacle are analyzed for different grafting\ndensities and different sub- or supercritical conditions, these properties\nbeing compared with the predictions of the corresponding ideal confined bundle\nmodel. In this analysis, non-ideal effects due to interactions between\nfilaments and confinement effects are singled out. For all state points\nconsidered at the same temperature and at the same gap width between the two\nsurfaces, the force per filament exerted on the opposite wall appears to be a\nfunction of a rescaled free monomer density $\\hat{\\rho}_1^{\\rm eff}$. This\nquantity can be estimated directly from the characteristic length of the\nexponential filament size distribution $P$ observed in the size domain where\nthese grafted filaments are not in direct contact with the wall. We also\nanalyze the dynamics of the filament contour length fluctuations in terms of\neffective polymerization ($U$) and depolymerization ($W$) rates, where again it\nis possible to disentangle non-ideal and confinement effects."
    },
    {
        "anchor": "Gaseous Diffusion as a Correlated Random Walk: The mean square displacement per collision of a molecule (also referred to as\na random walker or intruder) immersed in a gas at equilibrium is given by its\nmean square displacement between two consecutive collisions (mean square free\npath) corrected by a prefactor in the form of a series. The $(n+1)$-th term of\nthe series is directly proportional to the mean value of the projection of\n$\\mathbf{r}_i$ over $\\mathbf{r}_{i-n}$, being $\\mathbf{r}_i$ the displacement\nof the intruder between the $(i-1)$-th and $i$-th collision. In this article,\nwe provide simple arguments to derive an accurate approximate expression for\neach term of the series. Summation of this series enables the determination of\nboth the mean square displacement and the diffusion coefficient, which are\nexpressed exclusively in terms of two quantities: the mean square free path and\nthe mean persistence ratio (a quantity related to the correlation between\nvelocities before and after a collision). The key result in this random walk\napproach is that the ratio of two consecutive terms of the corrective series is\nwell approximated by the mean persistence ratio. We consider exact expressions\nfor the terms of this series and calculate the ratio of several consecutive\nterms for the case of hard spheres. We find that these ratios are indeed very\nwell approximated by the mean persistence ratio, which supports our approach.\nThese theoretical results are confirmed with Monte Carlo simulations of the\nBoltzmann equation. A simple and an improved expression for the diffusion\ncoefficient $D$ are derived. They are compared with the so-called first and\nsecond Sonine approximations to $D$ as well as with computer simulations of the\nBoltzmann equation. It is found that the improved random walk diffusion\ncoefficient exhibits a very good agreement with simulation results across all\nintruder and molecule mass ranges.",
        "positive": "Direct Measurement of Unsteady Microscale Stokes Flow Using Optically\n  Driven Microspheres: A growing body of work on the dynamics of eukaryotic flagella has noted that\ntheir oscillation frequencies are sufficiently high that the viscous\npenetration depth of unsteady Stokes flow is comparable to the scales over\nwhich flagella synchronize. Incorporating these effects into theories of\nsynchronization requires an understanding of the global unsteady flows around\noscillating bodies. Yet, there has been no precise experimental test on the\nmicroscale of the most basic aspects of such unsteady Stokes flow: the orbits\nof passive tracers and the position-dependent phase lag between the oscillating\nresponse of the fluid at a distant point and that of the driving particle.\nHere, we report the first such direct Lagrangian measurement of this unsteady\nflow. The method uses an array of $30$ submicron tracer particles positioned by\na time-shared optical trap at a range of distances and angular positions with\nrespect to a larger, central particle, which is then driven by an oscillating\noptical trap at frequencies up to $400$ Hz. In this microscale regime, the\ntracer dynamics is considerably simplified by the smallness of both inertial\neffects on particle motion and finite-frequency corrections to the Stokes drag\nlaw. The tracers are found to display elliptical Lissajous figures whose\norientation and geometry are in agreement with a low-frequency expansion of the\nunderlying dynamics, and the experimental phase shift between motion parallel\nand orthogonal to the oscillation axis exhibits a predicted scaling form in\ndistance and angle. Possible implications of these results for synchronization\ndynamics are discussed."
    },
    {
        "anchor": "Electrosteric enhanced stability of functional sub-10 nm cerium and iron\n  oxide particles in cell culture medium: Applications of nanoparticles in biology require that the nanoparticles\nremain stable in solutions containing high concentrations of proteins and\nsalts, as well as in cell culture media. In this work, we developed simple\nprotocols for the coating of sub-10 nm nanoparticles and evaluated the\ncolloidal stability of dispersions in various environments. Ligands (citric\nacid), oligomers (phosphonate-terminated poly(ethylene oxide)) and polymers\n(poly(acrylic acid)) were used as nanometer-thick adlayers for cerium (CeO2)\nand iron (gamma-Fe2O3) oxide nanoparticles. The organic functionalities were\nadsorbed on the particle surfaces via physical (electrostatic) forces.\nStability assays at high ionic strength and in cell culture media were\nperformed by static and dynamic light scattering. Among the three coating\nexamined, we found that only poly(acrylic acid) fully preserved the dispersion\nstability on the long term (> weeks). The improved stability was explained by\nthe multi-point attachments of the chains onto the particle surface, and by the\nadlayer-mediated electrosteric interactions. These results suggest that\nanionically charged polymers represent an effective alternative to conventional\ncoating agents.",
        "positive": "Stressed and sliding ice surfaces liquefy without much heating: The low kinetic friction observed between ice or snow and numerous\ncounterbodies is commonly attributed to a thin interfacial water layer [1-3],\nwhich is believed to exist because of pressure melting [4], surface melting [5,\n6], or friction-induced heating [7]. However, even the currently leading theory\nof frictional melting keeps being challenged, for example, due to the lack of\ndetectable warming of snow surfaces under a rotating slider at -7{\\deg}C\ntemperature and 1 m/s sliding velocity despite high temporospatial resolution\n[8]. Here we present molecular simulations of ice interfaces that reveal that\nice surfaces liquefy readily without melting thermally but rather by\ndisplacement driven amorphization, normal-stress gradients, and tensile\nin-plane stress. Yet, friction coefficients below 0.01, as observed during the\nsliding of hydrophobic solids over ice [9], appear possible only when the\ncounterfaces are smooth and allow water to slip past them. Our findings provide\nfundamental guidelines on how to optimize ice friction and challenge\nexperimentalists to measure the surface temperature of ice and snow at minute\nscales and with unprecedented speed."
    },
    {
        "anchor": "Random pinning elucidates the nature of melting transition in\n  two-dimensional core-softened potential system: Despite about forty years of investigations, the nature of the melting\ntransition in two dimensions is not completely clear. In the framework of the\nmost popular Berezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young (BKTHNY)\ntheory, 2D systems melt through two continuous Berezinskii-Kosterlitz-Thouless\n(BKT) transitions with intermediate hexatic phase. The conventional first-order\ntransition is also possible. On the other hand, recently on the basis of\ncomputer simulations the new melting scenario was proposed with continuous BKT\ntype solid-hexatic transition and first order hexatic-liquid transition.\nHowever, in the simulations the hexatic phase is extremely narrow that makes\nits study difficult. In the present paper, we propose to apply the random\npinning to investigate the hexatic phase in more detail. The results of\nmolecular dynamics simulations of two dimensional system having core-softened\npotentials with narrow repulsive step which is similar to the soft disk system\nare outlined. The system has a small fraction of pinned particles giving\nquenched disorder. Random pinning widens the hexatic phase without changing the\nmelting scenario and gives the possibility to study the behavior of the\ndiffusivity and order parameters in the vicinity of the melting transition and\ninside the hexatic phase.",
        "positive": "Superposition of droplet elasticity and volume fraction effects on\n  emulsion dynamics: The rheological properties of emulsions are of considerable importance in a\ndiverse range of scenarios. Here we describe a superposition of the effects of\ndroplet elasticity and volume fraction on the dynamics of emulsions. The\nsuperposition is governed by physical interactions between droplets, and\nprovides a new mechanism for modifying the flow behavior of emulsions, by\ncontrolling the elasticity of the dispersed phase. We investigate the\nproperties of suspensions of emulsified wormlike micelles (WLM). Dense\nsuspensions of the emulsified WLM droplets exhibit thermally responsive\nproperties in which the viscoelastic moduli decrease by an order of magnitude\nover a temperature range of 0 $^\\circ$C to 25 $^\\circ$C. Surprisingly, the\nfragility (i.e. the volume-fraction dependence of the modulus) of the emulsions\ndoes not change with temperature. Instead, the emulsion modulus scales as a\npower-law with volume fraction with a constant exponent across all temperatures\neven as the droplet properties change from elastic to viscous. Nevertheless,\nthe underlying droplet dynamics depend strongly on temperature. From stress\nrelaxation experiments, we quantify droplet dynamics across the cage breaking\ntime scale below which the droplets are locally caged by neighbors and above\nwhich the droplets escape their cages to fully relax. For elastic droplets and\nhigh volume fractions, droplets relax less stress through cage rattling and the\nterminal relaxations are slower than for viscous droplets and lower volume\nfractions. The cage rattling and cage breaking dynamics are highly correlated\nfor variations in both temperature and emulsion concentration, suggesting that\nthermal and volume fraction effects represent independent parameters to control\nemulsion properties."
    },
    {
        "anchor": "Structure and stability of chiral beta-tapes: a computational\n  coarse-grained approach: We present two coarse-grained models of different levels of detail for the\ndescription of beta-sheet tapes obtained from equilibrium self-assembly of\nshort rationally designed oligopeptides in solution. Here we only consider the\ncase of the homopolymer oligopeptides with the identical sidegroups attached,\nin which the tapes have a helicoid surface with two equivalent sides. The\ninfluence of the chirality parameter on the geometrical characteristics, namely\nthe diameter, inter-strand distance and pitch, of the tapes have been\ninvestigated. The two models are found to produceequivalent results suggesting\na considerable degree of universality in conformations of the tapes.",
        "positive": "Self-assembly of colloidal polymers via depletion-mediated lock and key\n  binding: We study the depletion-induced self-assembly of indented colloids. Using\nstate-of-the-art Monte Carlo simulation techniques that treat the depletant\nparticles explicitly, we demonstrate that colloids assemble by a lock-and-key\nmechanism, leading to colloidal polymerization. The morphology of the chains\nthat are formed depends sensitively on the size of the colloidal indentation,\nwith smaller values additionally permitting chain branching. In contrast to the\ncase of spheres with attractive patches, Wertheim's thermodynamic perturbation\ntheory fails to provide a fully quantitative description of the polymerization\ntransition. We trace this failure to a neglect of packing effects and we\nintroduce a modified theory that accounts better for the shape of the colloids,\nyielding improved agreement with simulation."
    },
    {
        "anchor": "Water diffusion in carbon nanotubes: interplay between confinement,\n  surface deformation and temperature: In this article we investigate through molecular dynamics simulations the\ndiffusion behavior of the TIP4P/2005 water when confined in pristine and\ndeformed carbon nanotubes (armchair and zigzag). To analyze different diffusive\nmechanisms, the water temperature was varied from $210\\leq T\\leq 380$~K. The\nresults of our simulations reveal that water present a non-Arrhenius to\nArrhenius diffusion crossover. The confinement shifts the diffusion transition\nto higher temperatures when compared with the bulk system. In addition, for\nnarrower nanotubes, water diffuses in a single line which leads to a mobility\nindependent of the activation energy.",
        "positive": "Active nematic defects in compressible and incompressible flows: We study the dynamics of active nematic films on a substrate driven by active\nflows with or without the incompressible constraint.Through simulations and\ntheoretical analysis, we show that arch patterns are stable in the compressible\ncase, whilst they become unstable under the incompressibility constraint. For\ncompressible flows at high enough activity, stable arches organize themselves\ninto a smectic-like pattern, which induce an associated global polar ordering\nof $+1/2$ nematic defects. By contrast, divergence-free flows give rise to a\nlocal nematic order of the $+1/2$ defects, consisting of anti-aligned pairs of\nneighboring defects, as established in previous studies."
    },
    {
        "anchor": "Inhomogeneous shear of orthotropic incompressible non-linearly elastic\n  solids: singular solutions and biomechanical interpretation: We present a detailed study of rectilinear shear deformation in the framework\nof orthotropic nonlinear elasticity, under Dirichlet and mixed-boundary\nconditions. We take a slab made of a soft matrix, reinforced with two families\nof extensible fibers. We consider the case where the shear occurs along the\nbissectrix of the angle between the two privileged directions aligned with the\nfibers. We show that if the two families of parallel fibers are mechanically\nequivalent, then only smooth solutions are possible, whereas if the mechanical\ndifferences among the two families of fibers is pronounced, then strain\nsingularities may develop. We determine the precise conditions for the\nexistence of such singular solutions for the standard reinforcing orthotropic\nmodel. We then extend our findings to some orthotropic models of interest in\nbiomechanical applications, and we discuss the possible relevance of the\nsingular solutions to biomechanics.",
        "positive": "Real-time observation of polyelectrolyte-induced binding of charged\n  bilayers: We present real-time observations by confocal microscopy of the dynamic\nbehavior of multilamellar vesicles (MLVs), composed of charged synthetic\nlipids, when put in contact with oppositely charged polyelectrolyte (PE)\nmolecules. We find that the MLVs exhibit astonishing morphological transitions,\nwhich result from the discrete and progressive binding of the charged bilayers\ninduced by a high PE concentration gradient. Our physical picture is confirmed\nby quantitative measurements of the fluorescence intensity as the bilayers bind\nto each other. The shape transitions lead eventually to the spontaneous\nformation of hollow capsules, whose thick walls are composed of lipid\nmultilayers condensed with PE molecules. This class of objects may have some\n(bio)technological applications."
    },
    {
        "anchor": "Self-avoidant memory effects on enhanced diffusion in a stochastic model\n  of environmentally responsive swimming droplets: Enhanced diffusion is an emergent property of many experimental microswimmer\nsystems that usually arises from a combination of ballistic motion with random\nreorientations. A subset of these systems, autophoretic droplet swimmers that\nmove as a result of Marangoni stresses, have additionally been shown to respond\nto local, self-produced chemical gradients that can mediate self-avoidance or\nself-attraction. Via this mechanism, we present a mathematical model\nconstructed to encode experimentally observed self-avoidant memory and\nnumerically study the effect of this particular memory on the enhanced\ndiffusion of such swimming droplets. To disentangle the enhanced diffusion due\nto the random reorientations from the enhanced diffusion due to the\nself-avoidant memory, we compare to the widely-used active Brownian model.\nParadoxically, we find that the enhanced diffusion is substantially suppressed\nby the self-avoidant memory relative to that predicted by only an equivalent\nreorientation persistence timescale in the active Brownian model. We attribute\nthis to transient self-caging that we propose is novel for self-avoidant\nsystems. Additionally, we further explore the model parameter space by\ncomputing emergent parameters that capture the velocity and reorientation\npersistence, thus finding a finite parameter domain in which enhanced diffusion\nis observable.",
        "positive": "Phase diagram of hard board like colloids from computer simulations: The rich mesophase polymorhism and the phase sequence of board-like colloids\ndepends critically on their shape anisometry. Implementing extensive Monte\nCarlo simulations, we calculated the full phase diagram of sterically\ninteracting board-like particles, for a range of experimentally accessible\nmolecular dimensions/anisometries of colloids of this shape. A variety of self\norganized mesophases including uniaxial and biaxial nematics, smectic, cubatic\nand columnar phases have been identified. Our results demonstrate clearly that\nthe molecular anisometry influences critically not only the structure and the\nsymmetry of the mesophases but also, and perhaps more interestingly, the phase\nsequence among them. New classes of phase sequences such as nematic-nematic\nand, for the first time, a direct transition from a discotic and a biaxial\nnematic to an orthogonal smectic A phase have been identified. The molecular\ngeometry requirements for such a phase behavior have been located."
    },
    {
        "anchor": "Chain level insights into tensile-compressive asymmetry in glassy and\n  semicrystalline polymers: Using molecular dynamics simulations, we provide chain-level insights into\nthe dissimilarities in rearrangements of polymers under uniaxial tensile and\ncompressive deformation in glassy and semicrystalline samples of varying chain\nlengths. The organization of polymers under tension and compression is\ndistinctively different. The chains align themselves along the tensile axis\nleading to a net global nematic ordering of their bonds and end-to-end vectors\nwhereas under compression, the polymers arrange themselves in a plane\nperpendicular to the compressive axis resulting in emergence of an anti-nematic\nordering of the bonds and the chain end-to-end vectors. Moreover, the degree of\npolymers unfolding is greater under tension and they deform less affinely when\ncompared to chains under compression. The difference between the two responses\nstrongly depends on the chain length and is the largest at intermediate chain\nlengths.",
        "positive": "Adhesion-induced phase separation of multiple species of membrane\n  junctions: A theory is presented for the membrane junction separation induced by the\nadhesion between two biomimetic membranes that contain two different types of\nanchored junctions (receptor/ligand complexes). The analysis shows that several\nmechanisms contribute to the membrane junction separation. These mechanisms\ninclude (i) the height difference between type-1 and type-2 junctions is the\nmain factor which drives the junction separation, (ii) when type-1 and type-2\njunctions have different rigidities against stretch and compression, the\n``softer'' junctions are the ``favored'' species, and the aggregation of the\nsofter junction can occur, (iii) the elasticity of the membranes mediates a\nnon-local interaction between the junctions, (iv) the thermally activated shape\nfluctuations of the membranes also contribute to the junction separation by\ninducing another non-local interaction between the junctions and renormalizing\nthe binding energy of the junctions. The combined effect of these mechanisms is\nthat when junction separation occurs, the system separates into two domains\nwith different relative and total junction densities."
    },
    {
        "anchor": "Precipitation in aqueous mixtures with addition of strongly hydrophilic\n  or hydrophobic solute: We examine phase separation in aqueous mixtures due to preferential solvation\nwith a low-density solute (hydrophilic ions or hydrophobic particles). For\nhydrophilic ions, preferential solvation can stabilize water domains enriched\nwith ions. This precipitation occurs in wide ranges of the temperature and the\naverage composition above a critical solute density $n_p$, where the mixture\nsolvent would be in a one-phase state without solute. The volume fraction of\nprecipitated domains tends to zero as the average solute density $\\bar n$ is\ndecreased to $n_p$ or as the interaction parameter $\\chi$ is decreased to a\ncritical value $\\chi_p$. If we start with one-phase states with ${\\bar n}>n_p$\nor $\\chi>\\chi_p$, precipitation proceeds via homogeneous nucleation or via\nheterogeneous nucleation, for example, around suspended colloids. In the latter\ncase, colliod particles are wrapped by thick wetting layers. We also predict a\nfirst-order prewetting transition for $\\bar n$ or $\\chi$ slightly below $n_p$\nor $\\chi_p$.",
        "positive": "Polymer solutions: from hard monomers to soft polymers: A coarse-graining strategy for dilute and semi-dilute solutions of\ninteracting polymers, and of colloid polymer mixtures is briefly described.\nMonomer degrees of freedom are traced out to derive an effective, state\ndependent pair potential between the polymer centres of mass. The cross-over\nbetween good and poor solvent conditions is discussed within a scaling\nanalysis. The method is extended to block copolymers represented as \"necklaces\"\nof soft \"blobs\", and its success is illustrated here in the case of a symmetric\ndiblock copolymer which exhibits microphase separation."
    },
    {
        "anchor": "Tensile Fracture of Welded Polymer Interfaces: Miscibility,\n  Entanglements and Crazing: Large-scale molecular simulations are performed to investigate tensile\nfailure of polymer interfaces as a function of welding time $t$. Changes in the\ntensile stress, mode of failure and interfacial fracture energy $G_I$ are\ncorrelated to changes in the interfacial entanglements as determined from\nPrimitive Path Analysis. Bulk polymers fail through craze formation, followed\nby craze breakdown through chain scission. At small $t$ welded interfaces are\nnot strong enough to support craze formation and fail at small strains through\nchain pullout at the interface. Once chains have formed an average of about one\nentanglement across the interface, a stable craze is formed throughout the\nsample. The failure stress of the craze rises with welding time and the mode of\ncraze breakdown changes from chain pullout to chain scission as the interface\napproaches bulk strength. The interfacial fracture energy $G_I$ is calculated\nby coupling the simulation results to a continuum fracture mechanics model. As\nin experiment, $G_I$ increases as $t^{1/2}$ before saturating at the average\nbulk fracture energy $G_b$. As in previous simulations of shear strength,\nsaturation coincides with the recovery of the bulk entanglement density. Before\nsaturation, $G_I$ is proportional to the areal density of interfacial\nentanglements. Immiscibiltiy limits interdiffusion and thus suppresses\nentanglements at the interface. Even small degrees of immisciblity reduce\ninterfacial entanglements enough that failure occurs by chain pullout and $G_I\n\\ll G_b$.",
        "positive": "On the swelling properties of pom-pom polymers: impact of backbone\n  length: The present work continues our previous studies of pom-pom molecule [K.\nHaydukivska, O. Kalyuzhnyi, V. Blavatska, and J. Ilnytskyi, J. Mol. Liq. 328,\n115456 (2021); Condens. Matter Phys. 25, 23302 (2022)]. The molecule consists\nof a linear backbone with two branching points at both ends, with\nfunctionalities $f_1$ and $f_2$. Here, the main attention is concentrated on\nstudying the impact of the central backbone length on the configurational\ncharacteristics of complex molecule, such as size and shape ratios. We apply\nboth a direct polymer renormalization scheme based on continuous chain model\nand the alternative Wei's method to analyze a set of size and shape properties\nof pom-pom polymers in dilute solution. The size ratio of a pom-pom and a chain\npolymer of the same total molecular mass is calculated with an excluded volume\ninteraction taken into account, and estimates for asphericity are found in\nGaussian approximation, whereas for the size ratio we found a monotonous\ndependence of the length of backbone at different functionalities of side arms.\nResults for asphericity show a non-trivial behaviour."
    },
    {
        "anchor": "Topological nanocolloids with facile electric switching of plasmonic\n  properties: Combining topology and plasmonics paradigms in nanocolloidal systems may\nenable new means of pre-engineering desired composite material properties. Here\nwe design and realize orientationally ordered assemblies of noble metal\nnanoparticles with genus-one topology and unusual long-range ordering mediated\nby their interactions with the surrounding nematic fluid host. Facile electric\nswitching of these composites is reminiscent to that of pristine liquid\ncrystals (LCs), but provides a means of reconfiguring the nanoparticle assembly\nand thus also the ensuing composite medium's optical properties. Our findings\nmay lead to formation of new molecular-colloidal soft matter phases with\nunusual optical properties as well as optical metamaterials.",
        "positive": "Spatially heterogenous dynamics in dense, driven granular flows: Interest in the dynamical arrest leading to a fluid --> solid transition in\nthermal and athermal systems has led to questions about the nature of these\ntransitions. These jamming transitions may be dependent on the influence of\nextended structures on the dynamics of the system. Here we show results from a\nsimple driven, dissipative, non-equilibrium system which exhibits dynamical\nheterogeneities similar to those observed in a supercooled liquid which is a\nsystem in thermal equilibrium. Observations of the time $\\tau_R(r)$ required\nfor a particular particle to move a distance $r$ reveal the existence of\nlarge-scale correlated dynamical regions with characteristic timescales chosen\nfrom a broad distribution. The mean squared displacement of ensembles of\nparticles with varying characteristic $\\tau_R(r)$ reveals an intriguing\nspatially heterogenous mobility. This suggests that a unified framework for\njamming will have to be based on the connection between the nature of these\nheterogeneities and the effective dynamics."
    },
    {
        "anchor": "Probing the Fluctuation-Dissipation Theorem in a Perrin-like Experiment: In this Letter, we present a new experimental approach to investigate the\neffective temperature concept as a generalization of the\nfluctuation-dissipation theorem (FDT) for nonequilibrium systems. Simultaneous\nmeasurements of diffusion coefficient and sedimentation velocity of heavy\ncolloids, embedded in a Laponite clay suspension, are performed with a\nfluorescence-recovery-based setup. This nonperturbative dual measurement,\nperformed at a single time in a single sample, allows for a direct application\nof the FDT to the tracer velocity observable. It thus provides a well-defined\nderivation of the effective temperature in this ageing colloidal gel. For a\nwide range of concentrations and ageing times, we report no violation of the\nFDT, with effective temperature agreeing with bath temperature. This result is\nconsistent with recent theoretical predictions on the coupling between the\nvelocity observable and nonequilibrium gels dynamics.",
        "positive": "Environment effects on the electric conductivity of the DNA: We present a theoretical analysis of the environment effects on charge\ntransport in double-stranded synthetic poly(G)-poly(C) DNA molecules attached\nto two ideal leads. Coupling of the DNA to the environment results in two\neffects: (i) localization of carrier functions due to the static disorder and\n(ii) phonon-induced scattering of the carrier between these localized states,\nresulting in hopping conductivity. A nonlinear Pauli master equation for\npopulations of localized states is used to describe the hopping transport and\ncalculate the electric current as a function of the applied bias. We\ndemonstrate that, although the electronic gap in the density of states shrinks\nas the disorder increases, the voltage gap in the $I-V$ characteristics becomes\nwider. Simple physical explanation of this effect is provided."
    },
    {
        "anchor": "Counterion adsorption on flexible polyelectrolytes: comparison of\n  theories: Counterion adsorption on a flexible polyelectrolyte chain in a spherical\ncavity is considered by taking a \"permuted\" charge distribution on the chain so\nthat the \"adsorbed\" counterions are allowed to move along the backbone. We\ncompute the degree of ionization by using self-consistent field theory (SCFT)\nand compare with the previously developed variational theory. Analysis of\nvarious contributions to the free energy in both theories reveals that the\nequilibrium degree of ionization is attained mainly as an interplay of the\nadsorption energy of counterions on the backbone, the translational entropy of\nthe small ions, and their correlated density fluctuations. Degree of ionization\ncomputed from SCFT is significantly lower than that from the variational\nformalism. The difference is entirely due to the density fluctuations of the\nsmall ions in the system, which are accounted for in the variational procedure.\nWhen these fluctuations are deliberately suppressed in the truncated\nvariational procedure, there emerges a remarkable quantitative agreement in the\nvarious contributing factors to the equilibrium degree of ionization, in spite\nof the fundamental differences in the approximations and computational\nprocedures used in these two schemes. Nevertheless, since the significant\neffects from density fluctuations of small ions are not captured by the SCFT,\nand due to the close agreement between SCFT and the other contributing factors\nin the more transparent variational procedure, the latter is a better\ncomputational tool for obtaining the degree of ionization.",
        "positive": "Chiral sedimentation of extended objects in viscous media: We study theoretically the chirality of a generic rigid object's\nsedimentation in a fluid under gravity in the low Reynolds number regime. We\nrepresent the object as a collection of small Stokes spheres or stokeslets, and\nthe gravitational force as a constant point force applied at an arbitrary point\nof the object. For a generic configuration of stokeslets and forcing point, the\nmotion takes a simple form in the nearly free draining limit where the\nstokeslet radius is arbitrarily small. In this case, the internal hydrodynamic\ninteractions between stokeslets are weak, and the object follows a helical path\nwhile rotating at a constant angular velocity $\\omega$ about a fixed axis. This\n$\\omega$ is independent of initial orientation, and thus constitutes a chiral\nresponse for the object. Even though there can be no such chiral response in\nthe absence of hydrodynamic interactions between the stokeslets, the angular\nvelocity obtains a fixed, nonzero limit as the stokeslet radius approaches\nzero. We characterize empirically how $\\omega$ depends on the placement of the\nstokeslets, concentrating on three-stokeslet objects with the external force\napplied far from the stokeslets. Objects with the largest $\\omega$ are aligned\nalong the forcing direction. In this case, the limiting $\\omega$ varies as the\ninverse square of the minimum distance between stokeslets. We illustrate the\nprevalence of this robust chiral motion with experiments on small macroscopic\nobjects of arbitrary shape."
    },
    {
        "anchor": "Statics and Dynamics of Strongly Charged Soft Matter: Soft matter materials, such as polymers, membranes, proteins, are often\nelectrically charged. This makes them water soluble, which is of great\nimportance in technological application and a prerequisite for biological\nfunction. We discuss a few static and dynamic systems that are dominated by\ncharge effects. One class comprises complexation between oppositely charged\nobjects, for example the adsorption of charged ions or charged polymers (such\nas DNA) on oppositely charged substrates of different geometry. The second\nclass comprises effective interactions between similarly charged objects. Here\nthe main theme is to understand the experimental finding that similarly and\nhighly charged bodies attract each other in the presence of multi-valent\ncounterions. This is demonstrated using field-theoretic arguments as well as\nMonte-Carlo simulations for the case of two homogeneously charged bodies.\nRealistic surfaces, on the other hand, are corrugated and also exhibit\nmodulated charge distributions, which is important for static properties such\nas the counterion-density distribution, but has even more pronounced\nconsequences for dynamic properties such as the counterion mobility. More\npronounced dynamic effects are obtained with highly condensed charged systems\nin strong electric fields. Likewise, an electrostatically collapsed highly\ncharged polymer is unfolded and oriented in strong electric fields. At the end\nof this review, we give a very brief account of the behavior of water at planar\nsurfaces and demonstrate using ab-initio methods that specific interactions\nbetween oppositely charged groups cause ion-specific effects that have recently\nmoved into the focus of interest.",
        "positive": "Conformational Transitions of Heteropolymers: We study conformational transitions of simple coarse-grained models for\nprotein-like heteropolymers on the simple cubic lattice and off-lattice,\nrespectively, by means of multicanonical sampling algorithms. The effective\nhydrophobic/polar models do not require the knowledge of the native topology\nfor a given sequence of residues as input. Therefore these models are eligible\nto investigate general properties of the tertiary folding behaviour of such\nprotein-like heteropolymers."
    },
    {
        "anchor": "A lattice Boltzmann model with random dynamical constraints: In this paper we introduce a modified lattice Boltzmann model (LBM) with the\ncapability of mimicking a fluid system with dynamic heterogeneities. The\nphysical system is modeled as a one-dimensional fluid, interacting with\nfinite-lifetime moving obstacles. Fluid motion is described by a lattice\nBoltzmann equation and obstacles are randomly distributed semi-permeable\nbarriers which constrain the motion of the fluid particles. After a lifetime\ndelay, obstacles move to new random positions. It is found that the\nnon-linearly coupled dynamics of the fluid and obstacles produces heterogeneous\npatterns in fluid density and non-exponential relaxation of two-time\nautocorrelation function.",
        "positive": "Fractional solitons in non-Euclidian elastic plates: We show that minimal-surface non-Euclidean elastic plates share the same\nlow-energy effective theory as Haldane's dimerized quantum spin chain. As a\nresult, such elastic plates support fractional excitations, which take the form\nof charge-$1/2$ solitons between degenerate states of the plates, in strong\nanalogy to their quantum counterpart. These fractional solitons exhibit\nproperties similar to fractional excitations in quantum fractional topological\nstates, including deconfinement and braiding, as well as unique new features\nsuch as holographic properties and diode-like nonlinear response, demonstrating\ngreat potentials for applications as mechanical metamaterials."
    },
    {
        "anchor": "Computational Steering of Cluster Formation in Brownian Suspensions: We simulate cluster formation of model colloidal particles interacting via\nDLVO (Derjaguin, Landau, Vervey, Overbeek) potentials. The interaction\npotentials can be related to experimental conditions, defined by the pH-value,\nthe salt concentration and the volume fraction of solid particles suspended in\nwater. The system shows different structural properties for different\nconditions, including cluster formation, a glass-like repulsive structure, or a\nliquid suspension. Since many simulations are needed to explore the whole\nparameter space, when investigating the properties of the suspension depending\non the experimental conditions, we have developed a steering approach to\ncontrol a running simulation and to detect interesting transitions from one\nregion in the configuration space to another. The advantages of the steering\napproach and the restrictions of its applicability due to physical constraints\nare illustrated by several example cases.",
        "positive": "Electron Magnetic Resonance: The Modified Bloch Equation: We find a modified Bloch equation for the electronic magnetic moment when the\nmagnetic moment explicitly contains a diamagnetic contribution (a magnetic\nfield induced magnetic moment arising from the electronic orbital angular\nmomentum) in addition to the intrinsic magnetic moment of the electron. The\nmodified Bloch is coupled to equations of motion for the position and momentum\noperators. In the presence of static and time varying magnetic field\ncomponents, the magnetic moment oscillates out of phase with the magnetic field\nand power is absorbed by virtue of the magnetic field induced magnetic moment,\neven in the absence of coupling to the environment. We explicitly work out the\nspectrum and absorption for the case of a $p$ state electron."
    },
    {
        "anchor": "Crossover in dynamics in the Kob-Andersen binary mixture glass-forming\n  liquid: Glass-forming liquids are broadly classified as being fragile or strong,\ndepending on the deviation from Arrhenius behavior of their relaxation times. A\nfragile to strong crossover is observed or inferred in liquids like water and\nsilica, and more recently also in metallic glasses and phase change alloys,\nleading to the expectation that such a crossover is more widely realised among\nglass formers. We investigate computationally the well-studied Kob-Andersen\nmodel, accessing temperatures well below the mode coupling temperature\n$T_{MCT}$. We find that relaxation times exhibit a crossover in dynamics around\n$T_{MCT}$, and discuss whether it bears characteristics of the fragile to\nstrong crossover. Several aspects of dynamical heterogeneity exhibit behavior\nmirroring the dynamical crossover, whereas thermodynamic quantities do not. In\nparticular, the Adam-Gibbs relation describing the relation between relaxation\ntimes and configurational entropy continues to hold below the dynamical\ncrossover, when anharmonic corrections to the vibrational entropy are included.",
        "positive": "Diffusion of an Inhomogeneous Vortex Tangle: The spatial diffusion of an inhomogeneous vortex tangle is studied\nnumerically with the vortex filament model. A localized initial tangle is\nprepared by applying a counterflow, and the tangle is allowed to diffuse freely\nafter the counterflow is turned off. Comparison with the solution of a\ngeneralization of the Vinen equation that takes diffusion into account leads to\na very small diffusion constant, as expected from simple theoretical\nconsiderations. The relevance of this result to recent experiments on the\ngeneration and decay of superfluid turbulence at very low temperatures is\ndiscussed."
    },
    {
        "anchor": "Multiple glass transitions in star polymer mixtures: Insights from\n  theory and simulations: The glass transition in binary mixtures of star polymers is studied by mode\ncoupling theory and extensive molecular dynamics computer simulations. In\nparticular, we have explored vitrification in the parameter space of size\nasymmetry $\\delta$ and concentration $\\rho_2$ of the small star polymers at\nfixed concentration of the large ones. Depending on the choice of parameters,\nthree different glassy states are identified: a single glass of big polymers at\nlow $\\delta$ and low $\\rho_2$, a double glass at high $\\delta$ and low\n$\\rho_2$, and a novel double glass at high $\\rho_2$ and high $\\delta$ which is\ncharacterized by a strong localization of the small particles. At low $\\delta$\nand high $\\rho_2$ there is a competition between vitrification and phase\nseparation. Centered in the $(\\delta, \\rho_2)$-plane, a liquid lake shows up\nrevealing reentrant glass formation. We compare the behavior of the dynamical\ndensity correlators with the predictions of the theory and find remarkable\nagreement between the two.",
        "positive": "Characterizing anomalous diffusion in crowded polymer solutions and gels\n  over five decades in time with variable-lengthscale fluorescence correlation\n  spectroscopy: The diffusion of macromolecules in cells and in complex fluids is often found\nto deviate from simple Fickian diffusion. One explanation offered for this\nbehavior is that molecular crowding renders diffusion anomalous, where the\nmean-squared displacement of the particles scales as $\\langle r^2 \\rangle\n\\propto t^{\\alpha}$ with $\\alpha < 1$. Unfortunately, methods such as\nfluorescence correlation spectroscopy (FCS) or fluorescence recovery after\nphotobleaching (FRAP) probe diffusion only over a narrow range of lengthscales\nand cannot directly test the dependence of the mean-squared displacement (MSD)\non time. Here we show that variable-lengthscale FCS (VLS-FCS), where the volume\nof observation is varied over several orders of magnitude, combined with a\nnumerical inversion procedure of the correlation data, allows retrieving the\nMSD for up to five decades in time, bridging the gap between diffusion\nexperiments performed at different lengthscales. In addition, we show that\nVLS-FCS provides a way to assess whether the propagator associated with the\ndiffusion is Gaussian or non-Gaussian. We used VLS-FCS to investigate two\nsystems where anomalous diffusion had been previously reported. In the case of\ndense cross-linked agarose gels, the measured MSD confirmed that the diffusion\nof small beads was anomalous at short lengthscales, with a cross-over to simple\ndiffusion around $\\approx 1~\\mu$m, consistent with a caged diffusion process.\nOn the other hand, for solutions crowded with marginally entangled dextran\nmolecules, we uncovered an apparent discrepancy between the MSD, found to be\nlinear, and the propagators at short lengthscales, found to be non-Gaussian.\nThese contradicting features call to mind the \"anomalous, yet Brownian\"\ndiffusion observed in several biological systems, and the recently proposed\n\"diffusing diffusivity\" model."
    },
    {
        "anchor": "Converting water adsorption and capillary condensation in useable forces\n  with simple porous inorganic thin films: This work reports an innovative humidity driven actuation concept based on\nBangham effect using simple nanoporous sol-gel silica thin films as humidity\nresponsive materials. Bilayer shaped actuators, consisting on a\nhumidity-sensitive active nanostructured silica film deposited on a polymeric\nsubstrate (Kapton) were demonstrated as an original mean to convert water\nmolecule adsorption and capillary condensation in useable mechanical work.\nReversible silica surface energy modifications by water adsorption and the\nenergy produced by the rigid silica film contraction, induced by water\ncapillary condensation in mesopores, were finely controlled and used as the\nenergy sources. The influence of the film nanostructure (microporosity,\nmesoporosity) and thickness, and of the polymeric support thickness, on the\nactuation force, on the movement speed, and on the amplitude of displacement\nare clearly evidenced and discussed. We show that the global mechanical\nresponse of such silica-based actuators can be easily adjusted to fabricate a\nhumidity variation triggered tailor-made actuation systems. This first insight\nin hard ceramic stimulus responsive materials may open the door toward new\ngeneration of surface chemistry driven actuation systems.",
        "positive": "Role of surface heterogeneous nucleation on nanoporous drug delivery\n  systems: In this work we investigate the use of nanoporous carrier as drug delivery\nsystems for hydrophobic molecules. By studying a model system made of porous\nsilicon loaded with beta-carotene, we unveil a fundamental limitation of these\ncarriers that is due to heterogeneous nucleation that imposes a tradeoff\nbetween the amount of drug loaded and the reproducibility of the release.\nNonetheless, such issue is an alternative and improved method, compared with\nthe standard induction time, to monitor the formation of heterogenously\nnucleated aggregates."
    },
    {
        "anchor": "Probabilistic Description of Traffic Breakdowns: We analyze the characteristic features of traffic breakdown. To describe this\nphenomenon we apply to the probabilistic model regarding the jam emergence as\nthe formation of a large car cluster on highway. In these terms the breakdown\noccurs through the formation of a certain critical nucleus in the metastable\nvehicle flow, which enables us to confine ourselves to one cluster model. We\nassume that, first, the growth of the car cluster is governed by attachment of\ncars to the cluster whose rate is mainly determined by the mean headway\ndistance between the car in the vehicle flow and, may be, also by the headway\ndistance in the cluster. Second, the cluster dissolution is determined by the\ncar escape from the cluster whose rate depends on the cluster size directly.\nThe latter is justified using the available experimental data for the\ncorrelation properties of the synchronized mode. We write the appropriate\nmaster equation converted then into the Fokker-Plank equation for the cluster\ndistribution function and analyze the formation of the critical car cluster due\nto the climb over a certain potential barrier. The further cluster growth\nirreversibly gives rise to the jam formation. Numerical estimates of the\nobtained characteristics and the experimental data of the traffic breakdown are\ncompared. In particular, we draw a conclusion that the characteristic intrinsic\ntime scale of the breakdown phenomenon should be about one minute and explain\nthe case why the traffic volume interval inside which traffic breakdown is\nobserved is sufficiently wide.",
        "positive": "Anomalous Diffusion of Self-Propelled Particles in Directed Random\n  Environments: We theoretically study the transport properties of self-propelled particles\non complex structures, such as motor proteins on filament networks. A general\nmaster equation formalism is developed to investigate the persistent motion of\nindividual random walkers, which enables us to identify the contributions of\nkey parameters: the motor processivity, and the anisotropy and heterogeneity of\nthe underlying network. We prove the existence of different dynamical regimes\nof anomalous motion, and that the crossover times between these regimes as well\nas the asymptotic diffusion coefficient can be increased by several orders of\nmagnitude within biologically relevant control parameter ranges. In terms of\nmotion in continuous space, the interplay between stepping strategy and\npersistency of the walker is established as a source of anomalous diffusion at\nshort and intermediate time scales."
    },
    {
        "anchor": "Adsorption-Induced Slip Inhibition for Polymer Melts on Ideal Substrates: Hydrodynamic slip of a liquid at a solid surface represents a fundamental\nphenomenon in fluid dynamics that governs liquid transport at small scales. For\npolymeric liquids, de Gennes predicted that the Navier boundary condition\ntogether with the theory of polymer dynamics imply extraordinarily large\ninterfacial slip for entangled polymer melts on ideal surfaces; this Navier-de\nGennes model was confirmed using dewetting experiments on ultra-smooth,\nlow-energy substrates. Here, we use capillary leveling - surface tension driven\nflow of films with initially non-uniform thickness - of polymeric films on\nthese same substrates. Measurement of the slip length from a robust\none-parameter fit to a lubrication model is achieved. We show that at the lower\nshear rates involved in leveling experiments as compared to dewetting ones, the\nemployed substrates can no longer be considered ideal. The data is instead\nconsistent with physical adsorption of polymer chains at the solid/liquid\ninterface. We extend the Navier-de Gennes description using one additional\nparameter, namely the density of physically adsorbed chains per unit surface.\nThe resulting formulation is found to be in excellent agreement with the\nexperimental observations.",
        "positive": "Metropolis simulations of the manipulation of DNA strands in solution: This paper has been withdrawn by the authors."
    },
    {
        "anchor": "Confined Multilamellae Prefer Cylindrical Morphology: By evaporating a drop of lipid dispersion we generate the myelin morphology\noften seen in dissolving surfactant powders. We explain these puzzling\nnonequilibrium structures using a geometric argument: The bilayer repeat\nspacing increases and thus the repulsion between bilayers decreases when a\nmultilamellar disk is converted into a myelin without gain or loss of material\nand with number of bilayers unchanged. Sufficient reduction in bilayer\nrepulsion can compensate for the cost in curvature energy, leading to a net\nstability of the myelin structure. A numerical estimate predicts the degree of\ndehydration required to favor myelin structures over flat lamellae.",
        "positive": "Escape dynamics of confined undulating worms: We investigate the escape dynamics of oligochaeta {\\it Lumbriculus\nvariegatus} by confining them to a quasi-2D circular chamber with a narrow exit\npassage. The worms move by performing undulatory and peristaltic strokes and\nuse their head to actively probe their surroundings. We show that the worms\nfollow the chamber boundary with occasional reversals in direction and with\nvelocities determined by the orientation angle of the body with respect to the\nboundary. The average time needed to reach the passage decreases with its width\nbefore approaching a constant, consistent with a boundary-following search\nstrategy. We model the search dynamics as a persistent random walk along the\nboundary and demonstrate that the head increasingly skips over the passage\nentrance for smaller passage widths due to body undulations. The simulations\ncapture the observed exponential time-distributions taken to reach the exit and\ntheir mean as a function of width when starting from random locations. Even\nafter the head penetrates the passage entrance, we find that the worm does not\nalways escape because the head withdraws rhythmically back into the chamber\nover distances set by the dual stroke amplitudes. Our study highlights the\nimportance of boundary following and body strokes in determining how active\nmatter escapes from enclosed spaces."
    },
    {
        "anchor": "Anisotropic dynamics of a self-assembled colloidal chain in an active\n  bath: Anisotropic macromolecules exposed to non-equilibrium (active) noise are very\ncommon in biological systems, and an accurate understanding of their\nanisotropic dynamics is therefore crucial. Here, we experimentally investigate\nthe dynamics of isolated chains assembled from magnetic microparticles at a\nliquid-air interface and moving in an active bath consisting of motile E. coli\nbacteria. We investigate both the internal chain dynamics and the anisotropic\ncenter-of-mass dynamics through particle tracking. We find that both the\ninternal and center-of-mass dynamics are greatly enhanced compared to the\npassive case, i.e., a system without bacteria, and that the center-of-mass\ndiffusion coefficient $D$ features a non-monotonic dependence as a function of\nthe chain length. Furthermore, our results show that the relationship between\nthe components of $D$ parallel and perpendicular with respect to the direction\nof the applied magnetic field is preserved in the active bath compared to the\npassive case, with a higher diffusion in the parallel direction, in contrast to\nprevious findings in the literature. We argue that this qualitative difference\nis due to subtle differences in the experimental geometry and conditions and\nthe relative roles played by long-range hydrodynamic interactions and\nshort-range collisions.",
        "positive": "Quenched Charge Disorder and Coulomb Interactions: We develop a general formalism to investigate the effect of quenched fixed\ncharge disorder on effective electrostatic interactions between charged\nsurfaces in a one-component (counterion-only) Coulomb fluid. Analytical results\nare explicitly derived for two asymptotic and complementary cases: i)\nmean-field or Poisson-Boltzmann limit (including Gaussian-fluctuations\ncorrection), which is valid for small electrostatic coupling, and ii)\nstrong-coupling limit, where electrostatic correlations mediated by counterions\nbecome significantly large as, for instance, realized in systems with\nhigh-valency counterions. In the particular case of two apposed and ideally\npolarizable planar surfaces with equal mean surface charge, we find that the\neffect of the disorder is nil on the mean-field level and thus the plates\nrepel. In the strong-coupling limit, however, the effect of charge disorder\nturns out to be additive in the free energy and leads to an enhanced long-range\nattraction between the two surfaces. We show that the equilibrium inter-plate\ndistance between the surfaces decreases for elevated disorder strength (i.e.\nfor increasing mean-square deviation around the mean surface charge), and\neventually tends to zero, suggesting a disorder-driven collapse transition."
    },
    {
        "anchor": "Nanorheology of active-passive polymer mixtures is topology-sensitive: We study the motion of dispersed nanoprobes in entangled active-passive\npolymer mixtures. By comparing the two architectures of linear vs.\nunconcatenated and unknotted circular polymers, we demonstrate that novel, rich\nphysics emerge. For both polymer architectures, nanoprobes of size smaller than\nthe entanglement threshold of the solution move faster as activity is increased\nand more energy is pumped in the system. For larger nanoprobes, a surprising\nphenomenon occurs: while in linear solutions they move qualitatively as before,\nin active-passive ring solutions nanoprobes {\\it decelerate} with respect to\nthe purely passive conditions. We rationalize this effect in terms of the\nnon-equilibrium, topology-dependent association (clustering) of nanoprobes to\nthe cold component of the ring mixture reminiscent of the recently discovered\n[Weber et al., Phys. Rev. Lett. 116, 058301 (2016)] phase separation in scalar\nactive-passive mixtures. We conclude with a potential connection to the\nmicrorheology of the chromatin in the nuclei of the cells.",
        "positive": "Two-step aging dynamics in enzymatic milk gels: Colloidal gels undergo a phenomenon known as physical aging, i.e., a\ncontinuous change of their physical properties with time after the gel point.\nTo date, most of the research effort on aging in gels has been focused on\nsuspensions of hard colloidal particles. In this letter, we tackle the case of\nsoft colloidal \"micelles\" comprised of proteins, where gelation is induced by\nthe addition of an enzyme. Using time-resolved mechanical spectroscopy, we\nmonitor the viscoelastic properties of a suspension of colloidal micelles\nthrough the sol-gel transition and its subsequent aging. We show that the\nmicroscopic scenario underpinning the macroscopic aging dynamics comprises two\nsequential steps. First, the gel microstructure undergoes rapid coarsening, as\nobserved by optical microscopy, followed by arrest. Second, aging occurs solely\nthrough a contact-driven mechanism, as evidenced by the square-root dependence\nof the yield stress with the elastic modulus measured at different ages of the\ngel. These results provide a comprehensive understanding of aging in enzymatic\nmilk gels, which is crucial not only for a broad range of dairy products, but\nalso for soft colloids in general."
    },
    {
        "anchor": "Glassy Dynamics of Simulated Polymer Melts: Coherent Scattering and Van\n  Hove Functions Part II: Dynamics in the alpha-Relaxation Regime: Whereas the first part of this paper dealt with the relaxation in the\nbeta-regime, this part investigates the final (alpha) relaxation of a simulated\npolymer melt consisting of short non-entangled chains above the critical\ntemperature Tc of mode-coupling theory (MCT). We monitor the intermediate\nincoherent as well as the coherent chain and coherent melt scattering functions\nover a wide range of wave numbers q. Upon approaching Tc the coherent\nalpha-relaxation time of the melt increases strongly close to the maximum of\nthe static structure factor of the melt. At q corresponding to the radius of\ngyration of the chain the melt relaxation time exhibits another maximum. The\ntemperature dependence of the relaxation times is well described by a power-law\nwith a q-dependent exponent in an intermediate temperature range. The\ntime-temperature superposition principle of MCT is clearly bourne out in the\nwhole range of wave numbers. An analysis of the alpha-decay using\nKohlrausch-Williams-Watts (KWW) functions reveals that the collective melt\nKWW-stretching exponent and KWW-relaxation times are modulated with the\nstructure factor. Furthermore, both incoherent and coherent KWW-times approach\nthe large-q prediction of MCT at q comparable to the maximum of the structure\nfactor. At small q a power law with exponent -3 is found for the coherent chain\nKWW-times similar to that of recent experiments.",
        "positive": "Colloidal brazil nut effect in sediments of binary charged suspensions: Equilibrium sedimentation density profiles of charged binary colloidal\nsuspensions are calculated by computer simulations and density functional\ntheory. For deionized samples, we predict a colloidal ``brazil nut'' effect:\nheavy colloidal particles sediment on top of the lighter ones provided that\ntheir mass per charge is smaller than that of the lighter ones. This effect is\nverifiable in settling experiments."
    },
    {
        "anchor": "Floppy modes and non-affine deformations in random fiber networks: We study the elasticity of random fiber networks. Starting from a microscopic\npicture of the non-affine deformation fields we calculate the macroscopic\nelastic moduli both in a scaling theory and a self-consistent effective medium\ntheory. By relating non-affinity to the low-energy excitations of the network\n(``floppy-modes'') we achieve a detailed characterization of the non-affine\ndeformations present in fibrous networks.",
        "positive": "Transport and Fractionation in Periodic Potential-Energy Landscapes: Objects driven through periodically modulated potential-energy landscapes in\ntwo dimensions can become locked in to symmetry-selected directions that are\nindependent of the driving force's orientation. We investigate this problem in\nthe overdamped limit, and demonstrate that the crossover from free-flowing to\nlocked-in transport can depend exponentially on an object's size, with this\nexceptional selectivity emerging from the periodicity of the environment."
    },
    {
        "anchor": "Evaporation of Colloidal Suspension Droplets over Oil-infused Slippery\n  Surfaces: Evaporative drying of colloidal droplets with different concentrations (Ci)\non liquid infused slippery substrate (LISS) surfaces fabricated over\nbiomimetically patterned sticky hydrophobic surfaces is reported here. These\nslippery surfaces remain stable under the aqueous droplets. The effective\nthickness of the infused oil layer (hE) was varied and its effect on the\nevaporation dynamics, wetting ridge formation and the final deposition pattern\nwere studied using an optical microscope as well as a contact angle goniometer.\nThe results were contrasted to those obtained over bare (oil-free) flat and\npatterned sticky surfaces. Unlike strong pinning and consequent peripheral ring\ndeposit invariably observed in evaporation of a colloidal droplet over a solid\nsurface (i.e. bare flat Sylgard 184 without oil), over a LISS, the dynamics,\nincluding the extent of pinning and the final deposit morphology, were found to\nbe strongly dependant on hE. Due to the presence of the underlying patterns,\nthe extent of pinning increased with a reduction in hE. Prolonged evaporation\nover a LISS leads to a uniform deposition due to gravity-induced settling of\nthe colloids followed by capillarity-mediated rearrangement of the particles.\nColloidal assembly at the droplet free surface and the droplet-wetting ridge\ninterface leads to a thinner encapsulating oil layer and faster drainage of the\nwetting ridge resulting in a higher evaporation rate before pinning of the\nsuspension droplets over all LISS surfaces.",
        "positive": "Multiscale modeling of solute diffusion in triblock copolymer membranes: We develop a multiscale simulation model for diffusion of solutes through\nporous triblock copolymer membranes. The approach combines two techniques:\nself-consistent field theory (SCFT) to predict the structure of the\nself-assembled, solvated membrane and on-lattice kinetic Monte Carlo (kMC)\nsimulations to model diffusion of solutes. Solvation is simulated in SCFT by\nconstraining the glassy membrane matrix while relaxing the brush-like membrane\npore coating against the solvent. The kMC simulations capture the resulting\nsolute spatial distribution and concentration-dependent local diffusivity in\nthe polymer-coated pores; we parameterize the latter using particle-based\nsimulations. We apply our approach to simulate solute diffusion through\nnonequilibrium morphologies of a model triblock copolymer, and we correlate\ndiffusivity with structural descriptors of the morphologies. We also compare\nthe model's predictions to alternative approaches based on simple lattice\nrandom walks and find our multiscale model to be more robust and systematic to\nparameterize. Our multiscale modeling approach is general and can be readily\nextended in the future to other chemistries, morphologies, and models for the\nlocal solute diffusivity and interactions with the membrane."
    },
    {
        "anchor": "The interplay of geometry and coarsening in multicomponent lipid\n  vesicles under the influence of hydrodynamics: We consider the impact of surface hydrodynamics on the interplay between\ncurvature and composition in coarsening processes on model systems for\nbiomembranes. This includes scaling laws and equilibrium configurations, which\nare investigated by computational studies of a surface two-phase flow problem\nwith additional phase-depending bending terms. These additional terms\ngeometrically favor specific configurations. We find that as in 2D the effect\nof hydrodynamics strongly depends on the composition. In situations where the\ncomposition allows a realization of a geometrically favored configuration, the\nhydrodynamics enhances the evolution into this configuration. We restrict our\nmodel and numerics to stationary surfaces and validate the numerical approach\nwith various benchmark problems and convergence studies.",
        "positive": "Regimes of strong electrostatic collapse of a highly charged\n  polyelectrolyte in a poor solvent: We perform extensive molecular dynamics simulations of a highly charged\nflexible polyelectrolyte (PE) chain in a poor solvent for the case when the\nchain is in a collapsed state and the electrostatic interactions, characterized\nby the reduced Bjerrum length $\\ell_B$, are strong. We detect the existence of\nseveral sub-regimes, $R_g \\sim \\ell_B^{-\\gamma}$, in the dependence of the\ngyration radius of the chain $R_g$ on $\\ell_B$. In contrast to a good solvent,\nthe exponent $\\gamma$ for a poor solvent crucially depends on the size and\nvalency of counterions. To explain the different sub-regimes we generalize the\nexisting counterion fluctuation theory by a more complete account of the volume\ninteractions in the free energy of the chain. These include interactions\nbetween the chain monomers, between monomers and counterions and the\ncounterions themselves. We also demonstrate that the presence of the condensed\ncounterions can modify the effective attraction among the chain monomers and\nimpact the sign of the second virial coefficient."
    },
    {
        "anchor": "Twirling Elastica: Kinks, Viscous Drag, and Torsional Stress: Biological filaments such as DNA or bacterial flagella are typically curved\nin their natural states. To elucidate the interplay of viscous drag, twisting,\nand bending in the overdamped dynamics of such filaments, we compute the\nsteady-state torsional stress and shape of a rotating rod with a kink. Drag\ndeforms the rod, ultimately extending or folding it depending on the kink\nangle. For certain kink angles and kink locations, both states are possible at\nhigh rotation rates. The agreement between our macroscopic experiments and the\ntheory is good, with no adjustable parameters.",
        "positive": "Mode-Coupling Theory as a Mean-Field Description of the Glass Transition: Mode-coupling theory (MCT) is conjectured to be a mean-field description of\ndynamics of the structural glass transition and the replica theory to be its\nthermodynamic counterpart. However, the relationship between the two theories\nremains controversial and quantitative comparison is lacking. In this Letter,\nwe investigate MCT for monatomic hard sphere fluids at arbitrary dimensions\nabove three and compare the results with replica theory. We find grave\ndiscrepancies between the predictions of two theories. While MCT describes the\nnonergodic parameter quantitatively better than the replica theory in three\ndimension, it predicts a completely different dimension dependence of the\ndynamical transition point. We find it to be due to the pathological behavior\nof the nonergodic parameters derived from MCT, which exhibit negative tails in\nreal space at high dimensions."
    },
    {
        "anchor": "Permeation dynamics of active swimmers through anisotropic porous walls: Natural habitats of most living microorganisms are distinguished by a complex\nstructure often formed by a porous medium such as soil. The dynamics and\ntransport properties of motile microorganisms are strongly affected by crowded\nand locally anisotropic environments. Using \\chlamy as a model system, we\nexplore the permeation of active colloids through a structured wall of\nobstacles by tracking microswimmers' trajectories and analysing their\nstatistical properties. Employing micro-labyrinths formed by cylindrical or\nelongated pillars, we demonstrate that the anisotropy of the pillar's form and\norientation strongly affects the microswimmers' dynamics on different time\nscales. Furthermore, we discuss the kinetics of the microswimmer exchange\nbetween two compartments separated by an array of pillars.",
        "positive": "Universal effective interactions of globular proteins close to\n  liquid-liquid phase separation: corresponding-states behavior reflected in\n  the structure factor: Intermolecular interactions in protein solutions in general contain many\ncontributions. If short-range attractions dominate, the state diagram exhibits\nliquid-liquid phase separation (LLPS) that is metastable with respect to\ncrystallization. In this case, the extended law of corresponding states (ELCS)\nsuggests that thermodynamic properties are insensitive to details of the\nunderlying interaction potential. Using lysozyme solutions, we investigate the\napplicability of the ELCS to the static structure factor and in how far\neffective colloidal interaction models can help to rationalize the phase\nbehavior and interactions of protein solutions in the vicinity of the LLPS\nbinodal. The (effective) structure factor has been determined by small-angle\nX-ray scattering (SAXS). It can be described by Baxter's adhesive hard-sphere\nmodel, which implies a single fit parameter from which the normalized second\nvirial coefficient $b_2$ is inferred and found to quantitatively agree with\nprevious results from static light scattering. The $b_2$ values are independent\nof protein concentration, but systematically vary with temperature and solution\ncomposition, i.e. salt and additive content. If plotted as a function of\ntemperature normalized by the critical temperature, the values of $b_2$ follow\na universal behaviour. These findings validate the applicability of the ELCS to\nglobular protein solutions and indicate that the ELCS can also be reflected in\nthe structure factor."
    },
    {
        "anchor": "Response of a Complex Fluid at Intermediate Distances: The viscoelastic response of complex fluids is length- and time-scale\ndependent, encoding information on intrinsic dynamic correlations and\nmesoscopic structure. We derive the subdominant response of such fluids at\nintermediate distances and show that it governs their dynamics over\nsurprisingly large length scales. Generalizing the framework of microrheology\nto include this response, we experimentally confirm the theory, thereby\nmeasuring the dynamic correlation length of F-actin networks, as well as their\nbulk and local viscoelastic properties.",
        "positive": "Active Particles on Curved Surfaces: Recent studies have highlighted the sensitivity of active matter to\nboundaries and their geometries. Here we develop a general theory for the\ndynamics and statistics of active particles on curved surfaces and illustrate\nit on two examples. We first show that active particles moving on a surface\nwith no ability to probe its curvature only exhibit steady-state\ninhomogeneities in the presence of orientational order. We then consider a\nstrongly confined 3D ideal active gas and compute its steady-state density\ndistribution in a box of arbitrary convex shape."
    },
    {
        "anchor": "Friction and Nonlinear Dynamics: The nonlinear dynamics associated with sliding friction forms a broad\ninterdisciplinary research field that involves complex dynamical processes and\npatterns covering a broad range of time and length scales. Progress in\nexperimental techniques and computational resources has stimulated the\ndevelopment of more refined and accurate mathematical and numerical models,\ncapable of capturing many of the essentially nonlinear phenomena involved in\nfriction.",
        "positive": "Two-Dimensional Polymers with Random Short-Range Interactions: We use complete enumeration and Monte Carlo techniques to study\ntwo-dimensional self-avoiding polymer chains with quenched ``charges'' $\\pm 1$.\nThe interaction of charges at neighboring lattice sites is described by $q_i\nq_j$. We find that a polymer undergoes a collapse transition at a temperature\n$T_{\\theta}$, which decreases with increasing imbalance between charges. At the\ntransition point, the dependence of the radius of gyration of the polymer on\nthe number of monomers is characterized by an exponent $\\nu_{\\theta} = 0.60 \\pm\n0.02$, which is slightly larger than the similar exponent for homopolymers. We\nfind no evidence of freezing at low temperatures."
    },
    {
        "anchor": "Hybrid lattice Boltzmann model for binary fluid mixtures: A hybrid lattice Boltzmann method (LBM) for binary mixtures based on the\nfree-energy approach is proposed. Non-ideal terms of the pressure tensor are\nincluded as a body force in the LBM kinetic equations, used to simulate the\ncontinuity and Navier-Stokes equations. The convection-diffusion equation is\nstudied by finite difference methods. Differential operators are discretized in\norder to reduce the magnitude of spurious velocities. The algorithm has been\nshown to be stable and reproducing the correct equilibrium behavior in simple\ntest configurations and to be Galilean invariant. Spurious velocities can be\nreduced of about an order of magnitude with respect to standard discretization\nprocedure.",
        "positive": "Design of nematic liquid crystals to control microscale dynamics: Dynamics of small particles, both living such as swimming bacteria and\ninanimate, such as colloidal spheres, has fascinated scientists for centuries.\nIf one could learn how to control and streamline their chaotic motion, that\nwould open technological opportunities in areas such as the transformation of\nstored or environmental energy into systematic motion, micro-robotics, and\ntransport of matter at the microscale. This overview presents an approach to\ncommand microscale dynamics by replacing an isotropic medium such as water with\nan anisotropic fluid, a nematic liquid crystal. Orientational order leads to\nnew dynamic effects, such as propagation of particle-like solitary waves. Many\nof these effects are still awaiting their detailed mathematical description. By\nusing plasmonic metamask photoalignment, the nematic director can be patterned\ninto predesigned structures that control dynamics of inanimate particles\nthrough the liquid crystal enabled nonlinear electrokinetics. Moreover,\nplasmonic patterning of liquid crystals allows one to command the dynamics of\nswimming bacteria, guiding their trajectories, polarity of swimming, and\nconcentration in space. The patterned director design can also be extended to\nliquid crystal elastomers, in which case the director gradients define the\ndynamic profile of elastomer coatings. Some of these systems form an\nexperimental playground for the exploration of out-of-equilibrium active\nmatter, in which the levels of activity, degree of orientational order and\npatterns of alignment can all be controlled independently of each other."
    },
    {
        "anchor": "Calibration of scanning acoustic microscopy for the differentiation\n  between unstable and stable atherosclerotic plaques by X-ray fluorescence\n  imaging: Although cardiovascular diseases are the leading cause of death globally,\nnon-invasive and inexpensive diagnostic tools for the identification of\nassociated unstable atherosclerotic plaques are not yet available. Scanning\nacoustic microscopy offers a high potential to fill this critical gap in\npatient care. However, convincing validation and calibration of this technique\nrequires high resolution maps of Ca concentrations of atherosclerotic plaques.\nHere, we demonstrate that synchrotron radiation-based X-ray fluorescence\nimaging with micrometer spatial resolution can provide such a gold standard.",
        "positive": "Withdrawing a solid from a bath: how much liquid is coated?: A solid withdrawn from a liquid bath entrains a film. In this review, after\nrecalling the predictions and results for pure Newtonian liquids coated on\nsimple solids, we analyze the deviations to this ideal case exploring\nsuccessively three potential sources of complexity: the liquid-air interface,\nthe bulk rheological properties of the liquid and the mechanical or chemical\nproperties of the solid. For these different complexities, we show that\nsignificant effects on the film thickness are observed experimentally and we\nsummarize the theoretical analysis presented in the literature, which attempt\nto rationalize these measurements."
    },
    {
        "anchor": "Thickening of viscoelastic flow in a model porous medium: We study numerically two-dimensional creeping viscoelastic flow past a\nbiperiodic square array of cylinders within the Oldroyd B, FENE-CR and FENE-P\nconstitutive models of dilute polymer solutions. Our results capture the\ninitial mild decrease then dramatic upturn ('thickening') seen experimentally\nin the drag coefficient as a function of increasing Weissenberg number. By\nsystematically varying the porosity of the flow geometry, we demonstrate two\nqualitatively different mechanisms underpinning this thickening effect: one\nthat operates in the highly porous case of widely spaced obstacles, and another\nfor more densely packed obstacles, with a crossover between these two\nmechanisms at intermediate porosities. We also briefly consider 2D creeping\nviscoelastic flow past a linear array of cylinders confined to a channel, where\nwe find that the flow is steady for all Weissenberg numbers explored.",
        "positive": "A Drop of Active Matter: We study theoretically the hydrodynamics of a fluid drop containing oriented\nfilaments endowed with active contractile or extensile stresses and placed on a\nsolid surface. The active stresses alter qualitatively the wetting properties\nof the drop, leading to new spreading laws and novel static drop shapes.\nCandidate systems for testing our predictions include cytoskeletal extracts\nwith motors and ATP, suspensions of bacteria or pulsatile cells, or fluids\nladen with artificial self-propelled colloids."
    },
    {
        "anchor": "Induced and endogenous acoustic oscillations in granular faults: The frictional properties of disordered systems are affected by external\nperturbations. These perturbations usually weaken the system by reducing the\nmacroscopic friction coefficient. This friction reduction is of particular\ninterest in the case of disordered systems composed of granular particles\nconfined between two plates, as this is a simple model of seismic fault.\nIndeed, in the geophysical context frictional weakening could explain the\nunexpected weakness of some faults, as well as earthquake remote triggering. In\nthis manuscript we review recent results concerning the response of confined\ngranular systems to external perturbations, considering the different\nmechanisms by which the perturbation could weaken a system, the relevance of\nthe frictional reduction to earthquakes, as well as discussing the intriguing\nscenario whereby the weakening is not monotonic in the perturbation frequency,\nso that a re-entrant transition is observed, as the system first enters a\nfluidized state and then returns to a frictional state.",
        "positive": "Spontaneous instabilities and stick-slip motion in a generalized\n  Hebraud-Lequeux model: We revisit the H\\'ebraud-Lequeux (HL) model for the rheology of jammed\nmaterials and argue that a possibly important time scale is missing from HL's\ninitial specification. We show that our generalization of the HL model\nundergoes interesting oscillating instabilities for a wide range of parameters,\nwhich lead to intermittent, stick-slip flows under constant shear rate. The\ninstability we find is akin to the synchronization transition of coupled\nelements that arises in many different contexts (neurons, fireflies, financial\nbankruptcies, etc.). We hope that our scenario could shed light on the commonly\nobserved intermittent, serrated flows of glassy materials under shear."
    },
    {
        "anchor": "Shear dilatancy in marginal solids: Shearing stresses can change the volume of a material via a nonlinear effect\nknown as shear dilatancy. We calculate the elastic dilatancy coefficient of\nsoft sphere packings and random spring networks, two canonical models of\nmarginal solids close to their rigidity transition. We predict a dramatic\nenhancement of dilatancy near rigidity loss in both materials, with a\nsurprising distinction: while packings expand under shear, networks contract.\nWe show that contraction in networks is due to the destabilizing influence of\nincreasing hydrostatic or uniaxial loads, which is counteracted in packings by\nthe formation of new contacts.",
        "positive": "Effect of Equilibration on Primitive Path Analyses of Entangled Polymers: We use recently developed primitive path analysis (PPA) methods to study the\neffect of equilibration on entanglement density in model polymeric systems.\nValues of N_e for two commonly used equilibration methods differ by a factor of\ntwo or three even though the methods produce similar large-scale chain\nstatistics. We find that local chain stretching in poorly equilibrated samples\nincreases entanglement density. The evolution of N_e with time shows that many\nentanglements are lost through fast processes such as chain retraction as the\nlocal stretching relaxes. Quenching a melt state into a glass has little effect\non N_e. Equilibration-dependent differences in short-scale structure affect the\ncraze extension ratio much less than expected from the differences in PPA\nvalues of N_e."
    },
    {
        "anchor": "Resolving stress state at crack tip to elucidate nature of elastomeric\n  fracture: Based on spatial-temporal resolved measurements of the stress field at crack\ntip based on polarized optical microscopy (str-POM), the stress analysis\napproach to elastomeric fracture uncovers new insights. We show new\nphenomenology in contrast to the standard description of linear elastic\nfracture mechanics (LEFM). First, str-POM measurements show emergence of a\nstress saturation zone whose dimension r_ss is independent of the stress\nintensity factor K. This elastic zone is plastic zone whose size would scale\nquadratically with K. The absence of stress divergence allows us to measure tip\nstress s_tip at the onset of fracture, identified as inherent material\nstrength, i.e., s_tip(F) = s_F(inh). We are able to explain why LEFM applies\nwell to elastomers, i.e., why toughness (either given as critical energy\nrelease rate Gc or critical stress intensity factor Kc) is a material constant,\nand we have identified parameters that determine the magnitude of toughness.\nSecond, the popular Rivlin-Thomas energy balance description of elastomeric\nfracture in pure shear has acquired a fresh and different interpretation based\non str-POM observations, which show that the stress buildup at cut tip\nexplicitly scales with specimen height h0, leading to Gc = wch0 being constant.\nThird, the str-POM observations reveal how elastomeric fracture occurs at a\ncommon Kc independent of specimen thickness. At a given load there is weaker\nstress buildup for a thicker specimen due to greater stress saturation at cut\ntip, and fracture is observed to occur at lower tip stress for a thicker\nspecimen.",
        "positive": "From caging to Rouse dynamics in polymer melts with intramolecular\n  barriers: a critical test of the Mode Coupling Theory: By means of computer simulations and solution of the equations of the Mode\nCoupling Theory (MCT), we investigate the role of the intramolecular barriers\non several dynamic aspects of non-entangled polymers. The investigated dynamic\nrange extends from the caging regime characteristic of glass-formers to the\nrelaxation of the chain Rouse modes. We review our recent work on this\nquestion, provide new results and critically discuss the limitations of the\ntheory. Solutions of the MCT for the structural relaxation reproduce\nqualitative trends of simulations for weak and moderate barriers. However a\nprogressive discrepancy is revealed as the limit of stiff chains is approached.\nThis disagreement does not seem related with dynamic heterogeneities, which\nindeed are not enhanced by increasing barrier strength. It is not connected\neither with the breakdown of the convolution approximation for three-point\nstatic correlations, which retains its validity for stiff chains. These\nfindings suggest the need of an improvement of the MCT equations for polymer\nmelts. Concerning the relaxation of the chain degrees of freedom, MCT provides\na microscopic basis for time scales from chain reorientation down to the caging\nregime. It rationalizes, from first principles, the observed devations from the\nRouse model on increasing the barrier strength. These include anomalous scaling\nof relaxation times, long-time plateaux, and non-monotonous wavelength\ndependence of the mode correlators."
    },
    {
        "anchor": "Wrapping of ellipsoidal nano-particles by fluid membranes: Membrane budding and wrapping of particles, such as viruses and\nnano-particles, play a key role in intracellular transport and have been\nstudied for a variety of biological and soft matter systems. We study\nnano-particle wrapping by numerical minimization of bending, surface tension,\nand adhesion energies. We calculate deformation and adhesion energies as a\nfunction of membrane elastic parameters and adhesion strength to obtain\nwrapping diagrams. We predict unwrapped, partially-wrapped, and\ncompletely-wrapped states for prolate and oblate ellipsoids for various aspect\nratios and particle sizes. In contrast to spherical particles, where\npartially-wrapped states exist only for finite surface tensions,\npartially-wrapped states for ellipsoids occur already for tensionless\nmembranes. In addition, the partially-wrapped states are long-lived, because of\nan increased energy cost for wrapping of the highly-curved tips. Our results\nsuggest a lower uptake rate of ellipsoidal particles by cells and thereby a\nhigher virulence of tubular viruses compared with icosahedral viruses, as well\nas co-operative budding of ellipsoidal particles on membranes.",
        "positive": "Competitive Clustering in a Bi-disperse Granular Gas: A bi-disperse granular gas in a compartmentalized system is experimentally\nfound to cluster competitively: Depending on the shaking strength, the\nclustering can be directed either towards the compartment initially containing\nmainly small particles, or to the one containing mainly large particles. The\nexperimental observations are quantitatively explained within a flux model."
    },
    {
        "anchor": "First-principles study on the specific heat jump in the glass transition\n  of silica glass and the Prigogine-Defay ratio: The most important characteristic of glass transition is a jump in specific\nheat $\\Delta C_{p}$. Despite its significance, no standard theory exists to\ndescribe it. In this study, first-principles molecular-dynamics (MD)\nsimulations are used to describe the glass transition of silica glass, which\npresents many challenges. The novel view that state variables are extended to\ninclude the equilibrium positions of atoms $\\{ \\bar{\\bf R}_{j} \\}$ is fully\nused in analyzing the simulation results. Decomposing the internal energy into\nthree components (structural, phonon, and thermal expansion energies) reveals\nthat the jump $\\Delta C_{p}$ of silica glass is entirely determined by the\ncomponent of structural energy. The reason for the small $\\Delta C_{p}$ is its\nhigh glass-transition temperature, which makes the fluctuation in the\nstructural energy insensitive to temperature changes. This significantly\naffects how the Prigogine-Defay ratio $\\it{\\Pi}$ is interpreted, which was\npreviously unknown. The ratio $\\it{\\Pi}$ represents the ratio of the total\nenergy change to the contribution of thermal expansion energy at the glass\ntransition. The general property, $\\it{\\Pi}>1$, of glasses indicates that glass\ntransitions occur mainly by changes in the structural energy. Silica glass is\nan extreme case in that the transition occurs entirely by the change in\ninternal structure, such as the distribution of the bending angle of Si--O--Si\nbond.",
        "positive": "Monte Carlo simulation of an strongly coupled XY model in three\n  dimensions: Many experimental studies, over the past two decades, have constantly\nreported a novel critical behavior for the transition from Smectic-A phase of\nliquid crystals to Hexatic-B phase with non-XY critical exponents. However\naccording to symmetry arguments this transition must belong to XY universality\nclass. Using an optimized Monte Carlo simulation technique based on\nmulti-histogram method, we have investigated phase diagram of a coupled XY\nmodel, proposed by Bruinsma and Aeppli (PRL {\\bf 48}, 1625 (1982)), in three\ndimensions. The simulation results demonstrate the existence of a tricritical\npoint for this model, in which two different orderings are established\nsimultaneously. This result verifies the accepted idea the large specific heat\nanomaly exponent observed for SmA-HexB transition could be due to the\noccurrence of this transition in the vicinity of a tricritical point"
    },
    {
        "anchor": "Chiral oily streaks in a smectic-A liquid crystal: The liquid crystal octylcyanobiphenyl (8CB) was doped with the chiral agent\nCB15 and spin-coated onto a substrate treated for planar alignment of the\ndirector, resulting in a film of thickness several hundred nm in the smectic-A\nphase. In both doped and undoped samples, the competing boundary conditions -\nplanar alignment at the substrate and vertical alignment at the free surface -\ncause the liquid crystal to break into a series of flattened hemicylinders to\nsatisfy the boundary conditions. When viewed under an optical microscope with\ncrossed polarizers, this structure results in a series of dark and light\nstripes (\"oily streaks\") of period ~ 1 $\\mu$m. In the absence of chiral dopant\nthe stripes run perpendicular to the substrate's easy axis. However, when doped\nwith chiral CB15 at concentrations up to c = 4 wt-%, the stripe orientation\nrotates by a temperature-dependent angle $\\phi$ with respect to the c = 0\nstripe orientation, where $\\phi$ increases monotonically with c. $\\phi$ is\nlargest just below the nematic -- smectic-A transition temperature TNA and\ndecreases with decreasing temperature. As the temperature is lowered, $\\phi$\nrelaxes to a steady-state orientation close to zero within ~1$^\\circ$ C of TNA.\nWe suggest that the rotation phenomenon is a manifestation of the surface\nelectroclinic effect: The rotation is due to the weak smectic order parameter\nand resulting large director tilt susceptibility with respect to the smectic\nlayer normal near TNA, in conjunction with an effective surface electric field\ndue to polar interactions between the liquid crystal and substrate.",
        "positive": "Phase Diagram and Snap-Off Transition for a Twisted Party Balloon: All children enjoy inflating balloons and twisting them into different shapes\nand animals. Snapping the balloon into two separate compartments is a necessary\nstep that bears resemblance to the pinch-off phenomenon for water droplet\ndetached from the faucet. In addition to testing whether balloons exhibit the\nproperties of self-similarity and memory effect that are often associated with\nthe latter event, we determine their phase diagram by experiments. It turns out\nthat a common party balloon does not just snap. They in fact can assume five\nmore shapes, i.e., straight, necking, wrinkled, helix, and supercoil, depending\non the twist angle and ratio of its length and diameter. Moreover, history also\nmatters due to their prominent hysteresis. One may shift the phase boundary\nor/and reshuffle the phases by untwisting or lengthening the balloon at\ndifferent twist angle and initial length. Heuristic models are provided to\nobtain analytic expressions for the phase boundaries."
    },
    {
        "anchor": "Optical and thermal effects in the neighborhood of the spherical layered\n  nanoparticle of the \"metallic core -- J-aggregate shell'' structure: The relations for the polarizability of the metallic nanoparticles, coated\nwith the shell of cyanine dyes, are obtained in the article. The frequency\ndependencies for light absorption and scattering efficiencies, the heating of\nthe composite nanoparticle and the electric field amplification in its\nneighborhood are studied. It is established that all the dependencies have\nthree maxima which correspond to the frequencies of hybrid plasmon-exciton\nresonance. It is shown that an increase in content of metal in the nanoparticle\ncauses a blue shift of the maxima from the visible part of the spectrum and a\nred shift of the maximum from ultraviolet frequency range. The issue of\napplication of metal-organic nanoparticles in nanomedicine, in particular for\nthe photothermal therapy of malignant neoplasms is studied.",
        "positive": "The boundary element approach to Van der Waals interactions: We develop a boundary element method to calculate Van der Waals interactions\nfor systems composed of domains of spatially constant dielectric response. We\nachieve this by rewriting the interaction energy expression exclusively in\nterms of surface integrals of surface operators. We validate this approach in\nthe Lifshitz case and give numerical results for the interaction of two spheres\nas well as the van der Waals self-interaction of a uniaxial ellipsoid. Our\nmethod is simple to implement and is particularly suitable for a full,\nnon-perturbative numerical evaluation of non-retarded van der Waals\ninteractions between objects of a completely general shape."
    },
    {
        "anchor": "Anomalous Molecular Weight Dependence of Chain Dynamics in Unentangled\n  Polymer Blends with Strong Dynamic Asymmetry: We address the general question of how the molecular weight dependence of\nchain dynamics in unentangled polymers is modified by blending. By dielectric\nspectroscopy we measure the normal mode relaxation of polyisoprene in blends\nwith a slow matrix of poly(ter-butylstyrene). Unentangled polyisoprene in the\nblend exhibits strong deviations from Rouse scaling, approaching\n'entangled-like' behavior at low temperatures in concomitance with the increase\nof the dynamic asymmetry in the blend. The obtained results are discussed in\nthe framework of the generalized Langevin equation formalism. On this basis, a\nnon trivial relationship between the molecular weight dependence of the longest\nchain relaxation time and the nonexponentiality of the corresponding Rouse\ncorrelator is found. This result is confirmed by molecular dynamics\nsimulations.",
        "positive": "Micro-fabrication of Carbon Structures by Pattern Miniaturization in\n  Resorcinol-Formaldehyde Gel: A simple and novel method to fabricate and miniaturize surface and\nsub-surface micro-structures and micro-patterns in glassy carbon is proposed\nand demonstrated. An aqueous resorcinol-formaldehyde (RF) sol is employed for\nmicro-molding of the master-pattern to be replicated, followed by controlled\ndrying and pyrolysis of the gel to reproduce an isotropically shrunk replica in\ncarbon. The miniaturized version of the master-pattern thus replicated in\ncarbon is about one order of magnitude smaller than original master by\nrepeating three times the above cycle of molding and drying. The\nmicro-fabrication method proposed will greatly enhance the toolbox for a facile\nfabrication of a variety of Carbon-MEMS and C-microfluidic devices."
    },
    {
        "anchor": "A Liquid Crystal Model of Viral DNA Encapsidation: A liquid crystal continuum modeling framework for icosahedra bacteriophage\nviruses is developed and tested. The main assumptions of the model are the\nchromonic columnar hexagonal structure of confined DNA, the high resistance to\nbending and the phase transition from solid to fluid-like states as the\nconcentration of DNA in the capsid decreases during infection. The model\npredicts osmotic pressure inside the capsid and the ejection force of the DNA\nas well as the size of the isotropic volume at the center of the capsid.\nExtensions of the model are discussed.",
        "positive": "Vibration Improves Performance in Granular Jamming Grippers: Granular jamming is a popular soft robotics technology that has seen recent\nwidespread applications including industrial gripping, surgical robotics and\nhaptics. However, to date the field has not fully exploited the fundamental\nscience of the jamming phase transition, which has been rigorously studied in\nthe field of statistical and condensed matter physics. This work introduces\nvibration as a means to improve the properties of granular jamming grippers\nthrough vibratory fluidisation and the exploitation of resonant modes within\nthe granular material. We show that vibration in soft jamming grippers can\nimprove holding strength, reduce the downwards force needed for the gripping\naction, and lead to a simplified setup where the second air pump, generally\nused for unjamming, could be removed. In a series of studies, we show that\nfrequency and amplitude of the waveforms are key determinants to performance,\nand that jamming performance is also dependent on temporal properties of the\ninduced waveform. We hope to encourage further study in transitioning\nfundamental jamming mechanisms into a soft robotics context to improve\nperformance and increase diversity of applications for granular jamming\ngrippers."
    },
    {
        "anchor": "Effect of local stress on accurate modeling of bacterial outer membranes\n  using all-atom molecular dynamics: Biological membranes are fundamental components of living organisms that play\nan undeniable role in their survival. Molecular dynamics (MD) serves as an\nessential computational tool for studying biomembranes on molecular and\natomistic scales. The status quo of MD simulations of biomembranes studies a\nnanometer-sized membrane patch periodically extended under periodic boundary\nconditions (PBC). In nature, membranes are usually composed of different lipids\nin their two layers (referred to as leaflets). This compositional asymmetry\nimposes a fixed ratio of lipid numbers between the two leaflets in a\nperiodically constrained membrane, which needs to be set appropriately. The\nwidely adopted methods of defining leaflet lipid ratio suffer from the lack of\ncontrol over the mechanical tension of each leaflet, which could significantly\ninfluence research findings. In this study, we investigate the role of\nmembrane-building protocol and the resulting initial stress state on the\ninteraction between small molecules and asymmetric membranes. We model the\nouter membrane of Pseudomonas aeruginosa bacteria using two different building\nprotocols and probe their interactions with the Pseudomonas Quinolone Signal\n(PQS). Our results show that differential stress could shift the position of\nfree energy minimum for the PQS molecule between the two leaflets of the\nasymmetric membrane. This work provides critical insights into the relationship\nbetween the initial per-leaflet tension and the spontaneous intercalation of\nPQS.",
        "positive": "Segregation patterns in binary mixtures with same layer-thicknesses\n  under vertical vibration: Inspired by the theoretical prediction [Phys. Rev. Lett. 86, 3423 (2001)] and\nthe disputed experimental results [Phys. Rev. Lett. 89, 189601(2002), Phys.\nRev. Lett. 90, 014302 (2003)], we systematically investigate the pattern of\nbinary mixtures consisting of same layer-thickness under vertical vibration.\nVarious kinds of mixtures with different diameters and densities particles are\nused to observe the separation regime. It is found that these mixtures behave\nlike five kinds of segregation patterns for different driving control\nparameters, i.e., Brazil nut (BN), reversed Brazil nut (RBN), Mixed states,\nlight-BN (LBN), and light-RBN (LRBN), where the latter two regimes are neither\npurely segregated nor completely mixed states. Not only that, but LBN (LRBN) is\nobserved to be the transition path from BN (RBN) to Mixed state. Moreover, BN\nphenomenon takes place in the area of low density ratio and found to be\nindependent of layer structure, while RBN is sensitive to the layer structure\nand occurs at the large density ratio but lower diameter ratio. Our result may\nbe helpful for the establishment of theory about the segregation and mixing of\ngranular mixtures."
    },
    {
        "anchor": "Reentrant melting of the exp-6 fluid: the role of the repulsion softness: We investigate the phase behaviour of a system of particles interacting\nthrough the exp-6 pair potential, a model interaction that is appropriate to\ndescribe effective interatomic forces under high compression. The\nsoft-repulsive component of the potential is being varied so as to study the\neffect on reentrant melting and density anomaly. Upon increasing the repulsion\nsoftness, we find that the anomalous melting features persist and occur at\nsmaller pressures. Moreover, if we reduce the range of downward concavity in\nthe potential by extending the hard core at the expenses of the soft-repulsive\nshoulder, the reentrant part of the melting line reduces in extent so as it\ndoes the region of density anomaly.",
        "positive": "Reflection and Exclusion of Shear Zones in Inhomogeneous Granular\n  Materials: Shear localization in granular materials is studied experimentally and\nnumerically. The system consists of two material layers with different\neffective frictions. The presence of the material interface leads to a special\ntype of \"total internal reflection\" of the shear zone. In a wide range of\nconfigurations the reflection is characterized by a fixed angle which is\nanalogous to the critical angle of refraction in optics. The zone leaves and\nreenters the high friction region at this critical angle and in between it\nstays near the interface in the low friction region. The formalism describing\nthe geometry of the shear zones and that of refracted and reflected light beams\nis very similar. For the internal visualization of shear localization two\nindependent experimental techniques were used (i) excavation and (ii) Magnetic\nResonance Imaging."
    },
    {
        "anchor": "Activity-induced droplet propulsion and multifractality: We develop a minimal hydrodynamic model, without an orientational order\nparameter, for assemblies of contractile swimmers encapsulated in a droplet of\na binary-fluid emulsion. Our model uses two coupled scalar order parameters,\n$\\phi$ and $\\psi$, which capture, respectively, the droplet interface and the\nactivity of the contractile swimmers inside this droplet. These order\nparameters are also coupled to the velocity field $\\bm u$. At low activity, our\nmodel yields a self-propelling droplet whose center of mass $(CM)$ displays\nrectilinear motion, powered by the spatiotemporal evolution of the field\n$\\psi$, which leads to a time-dependent vortex dipole at one end of the\ndroplet. As we increase the activity, this $CM$ shows chaotic super-diffusive\nmotion, which we characterize by its mean-square displacement; and the droplet\ninterface exhibits multifractal fluctuations, whose spectrum of exponents we\ncalculate. We explore the implications of our results for experiments on active\ndroplets of contractile swimmers.",
        "positive": "Structure and Fragmentation in Colloidal Artificial Molecules and Nuclei: Motivated by recent experiments on colloidal systems with competing\nattractive and repulsive interactions, we simulate a two-dimensional system of\ncolloids with competing interactions that can undergo fragmentation. In the\nabsence of any other confining potential, the colloids can form stable clusters\ndepending on the strength of the short range attractive term. By suddenly\nchanging the strength of one of the interaction terms we find a rich variety of\nfragmentation behavior which is affected by the existence of \"magic\" cluster\nnumbers. Such soft matter systems can be used to construct artificial nuclei."
    },
    {
        "anchor": "Darcy law for yield stress fluid: Predicting the flow of non-Newtonian fluids in porous structure is still a\nchallenging issue due to the interplay betwen the microscopic disorder and the\nnon-linear rheology. In this letter, we study the case of an yield stress fluid\nin a two-dimensional structure. Thanks to a performant optimization algorithm,\nwe show that the system undergoes a continuous phase transition in the behavior\nof the flow controlled by the applied pressure drop. In analogy with the\nstudies of the plastic depinning of vortex lattices in high-$T_c$\nsuperconductors we characterize the nonlinearity of the flow curve and relate\nit to the change in the geometry of the open channels. In particular, close to\nthe transition, an universal scale free distribution of the channel length is\nobserved and explained theoretically via a mapping to the KPZ equation.",
        "positive": "Ferromagnetic filament shapes in a rotating field reveal their\n  magnetoelastic properties: Flexible ferromagnetic filaments can be used to control the flow on the\nmicro-scale with external magnetic field. To accurately model them, it is\ncrucial to know their parameters such as their magnetization and bending\nmodulus, the latter of which is hard to determine precisely. We present a\nmethod how the ferromagnetic filament's shape in a rotating field can be used\nto determine the magnetoelastic number $Cm$ - the ratio of magnetic to elastic\nforces. Then once the magnetization of the filament is known, it is possible to\ndetermine its bending modulus. The main idea of the method is that $Cm$ is the\nonly parameter that determines whether the filament is straight or whether its\ntips are bent towards the magnetic field direction. Comparing with numerical\nsolutions, we show that the method results in an error of $15...20\\%$ for the\ndetermined $Cm$, what is more precise than estimations from other methods. This\nmethod will allow to improve the comparability between theoretical filament\nmodels and experimental measurements."
    },
    {
        "anchor": "Physics of counterion mediated attractions between double-stranded DNAs: Attraction between two indentical objects uniformly charged in solution seems\nintuitively surprising on the one hand because we know that such objects do\nrepel in vacuum and on another hand because this simple mental picture is still\npreserved within the Poisson-Boltzmann theory of ion-mediated interactions. We\nwill see, however, that by relaxing some contraints on the models used, one can\nfind ion-mediated attraction between uniformly charged objects in solution.\nThis allows to give some insights on the possible way two DNA double strands\nattract each other in many biologically relevant cases.",
        "positive": "Phase separation dynamics in deformable droplets: Phase separation can drive spatial organization of multicomponent mixtures.\nFor instance in developing animal embryos, effective phase separation\ndescriptions have been used to account for the spatial organization of\ndifferent tissue types. Similarly, separation of different tissue types and the\nemergence of a polar organization is also observed in cell aggregates mimicking\nearly embryonic axis formation. Here, we describe such aggregates as deformable\ntwo-phase fluid droplets, which are suspended in a fluid environment (third\nphase). Using hybrid finite-volume Lattice-Boltzmann simulations, we\nnumerically explore the out-of-equilibrium routes that can lead to the polar\nequilibrium state of such a droplet (Janus droplet). We focus on the interplay\nbetween spinodal decomposition and advection with hydrodynamic flows driven by\ninterface tensions, which we characterize by a Peclet number $Pe$. Consistent\nwith previous work, for large $Pe$ the coarsening process is generally\naccelerated. However, for intermediate $Pe$ we observe long-lived, strongly\nelongated droplets, where both phases form an alternating stripe pattern. We\nshow that these ``croissant'' states are close to mechanical equilibrium and\ncoarsen only slowly through diffusive fluxes in an Ostwald-ripening-like\nprocess. Finally, we show that a surface tension asymmetry between both droplet\nphases leads to transient, rotationally symmetric states whose resolution leads\nto flows reminiscent of Marangoni flows. Our work highlights the importance of\nadvection for the phase separation process in finite, deformable systems."
    },
    {
        "anchor": "Experimental Investigation of Plastic Deformations Before Granular\n  Avalanche: We present an experimental study of the deformation inside a granular\nmaterial that is progressively tilted. We investigate the deformation before\nthe avalanche with a spatially resolved Diffusive Wave Spectroscopy setup. At\nthe beginning of the inclination process, we first observe localized and\nisolated events in the bulk, with a density which decreases with the depth. As\nthe angle of inclination increases, series of micro-failures occur periodically\nin the bulk, and finally a granular avalanche takes place. The micro-failures\nare observed only when the tilt angles are larger than a threshold angle much\nsmaller than the granular avalanche angle. We have characterized the density of\nreorganizations and the localization of micro-failures. We have also explored\nthe effect of the nature of the grains, the relative humidity conditions and\nthe packing fraction of the sample. We discuss those observations in the\nframework of the plasticity of granular matter. Micro-failures may then be\nviewed as the result of the accumulation of numerous plastic events.",
        "positive": "Destabilization and phase separation of particle suspensions in\n  emulsions: Yield stress fluids are widely used in industrial application to arrest dense\nsolid particles, which can be studied by using a concentrated emulsion as a\nmodel fluid. We show in experiments that particle sedimentation in emulsions\ncannot be predicted by the classical criterion for spheres embedded in a yield\nstress fluid. Phase separation processes take place, where a liquid layer forms\nand particle sedimentation is enhanced by the emulsion drainage. In addition,\nemulsion drainage can be arrested or enhanced by the amount of particles\nembedded in the emulsion. A minimal mathematical model is developed and solved\nin numerical simulations to describe the emulsion drainage in the presence of\nparticles, which favorably compares with the experimental stability diagram and\nthe sedimentation dynamics."
    },
    {
        "anchor": "Polymer Translocation out of Planar Confinements: Polymer translocation in three dimensions out of planar confinements is\nstudied in this paper. Three membranes are located at $z=-h$, $z=0$ and\n$z=h_1$. These membranes are impenetrable, except for the middle one at $z=0$,\nwhich has a narrow pore. A polymer with length $N$ is initially sandwiched\nbetween the membranes placed at $z=-h$ and $z=0$ and translocates through this\npore. We consider strong confinement (small $h$), where the polymer is\nessentially reduced to a two-dimensional polymer, with a radius of gyration\nscaling as $R^{\\tinytext{(2D)}}_g \\sim N^{\\nu_{\\tinytext{2D}}}$; here,\n$\\nu_{\\tinytext{2D}}=0.75$ is the Flory exponent in two dimensions. The polymer\nperforms Rouse dynamics. Based on theoretical analysis and high-precision\nsimulation data, we show that in the unbiased case $h=h_1$, the dwell-time\n$\\tau_d$ scales as $N^{2+\\nu_{\\tinytext{2D}}}$, in perfect agreement with our\npreviously published theoretical framework. For $h_1=\\infty$, the situation is\nequivalent to field-driven translocation in two dimensions. We show that in\nthis case $\\tau_d$ scales as $N^{2\\nu_{\\tinytext{2D}}}$, in agreement with\nseveral existing numerical results in the literature. This result violates the\nearlier reported lower bound $N^{1+\\nu}$ for $\\tau_d$ for field-driven\ntranslocation. We argue, based on energy conservation, that the actual lower\nbound for $\\tau_d$ is $N^{2\\nu}$ and not $N^{1+\\nu}$. Polymer translocation in\nsuch theoretically motivated geometries thus resolves some of the most\nfundamental issues that are the subjects of much heated debate in recent times.",
        "positive": "Experimental study of out of equilibrium fluctuations in a colloidal\n  suspension of Laponite using optical traps: This work is devoted to the study of displacement fluctuations of\nmicron-sized particles in an aging colloidal glass. We address the issue of the\nvalidity of the fluctuation dissipation theorem (FDT) and the time evolution of\nviscoelastic properties during aging of aqueous suspensions of a clay (Laponite\nRG) in a colloidal glass phase. Given the conflicting results reported in the\nliterature for different experimental techniques, our goal is to check and\nreconcile them using \\emph{simultaneously} passive and active microrheology\ntechniques. For this purpose we measure the thermal fluctuations of micro-sized\nbrownian particles immersed in the colloidal glass and trapped by optical\ntweezers. We find that both microrheology techniques lead to compatible results\neven at low frequencies and no violation of FDT is observed. Several\ninteresting features concerning the statistical properties and the long time\ncorrelations of the particles are observed during the transition."
    },
    {
        "anchor": "Drift of suspended single-domain nanoparticles in a harmonically\n  oscillating gradient magnetic field: We study the nonlinear dynamics of single-domain ferromagnetic nanoparticles\nin a viscous liquid induced by a harmonically oscillating gradient magnetic\nfield in the absence and presence of a static uniform magnetic field. Under\nsome physically reasonable assumptions, we derive a coupled set of stiff\nordinary differential equations for the magnetization angle and particle\ncoordinate describing the rotational and translational motions of\nnanoparticles. Analytical solutions of these equations are determined for\nnanoparticles near and far from the coordinate origin, and their correctness is\nconfirmed numerically. We show that if a uniform magnetic field is absent, the\nmagnetization angle and particle coordinate of each nanoparticle are periodic\nfunctions of time. In contrast, the presence of a uniform magnetic field makes\nthese functions aperiodic. In this case, we perform a detailed analysis of the\nnanoparticle dynamics and predict the appearance of the drift motion (directed\ntransport) of nanoparticles. We calculate both analytically and numerically the\ndrift velocity, study its dependence on time and model parameters, analyze the\nphysical origin of the drift phenomenon and discuss its potential biomedical\napplications.",
        "positive": "Wetting in the presence of the electric field: The classical density\n  functional theory study for a model system: We discuss the effect of an external electric field on the wetting of a solid\nsurface by liquid. To this end, we use a model of the two-level-atom fluid for\nwhich the changes in interatomic interactions due to the presence of the field\ncan be found using quantum-mechanical perturbation theory. Constructing the\ngrand potential functional, we perform the standard calculations of Young's\nequilibrium contact angle. The switching on of the electric field $|{\\bf {E}}|\n> 0$ may increase noticeably the contact angle $\\theta$."
    },
    {
        "anchor": "Novel structural features of the ripple phase of phospholipids: We have calculated the electron density maps of the ripple phase of\ndimyristoylphosphatidylcholine (DMPC) and palmitoyl-oleoyl phosphatidylcholine\n(POPC) multibilayers at different temperatures and fixed relative humidity. Our\nanalysis establishes, for the first time, the existence of an average tilt of\nthe hydrocarbon chains of the lipid molecules along the direction of the ripple\nwave vector, which we believe is responsible for the occurrence of asymmetric\nripples in these systems.",
        "positive": "Dynamics of end-pulled polymer translocation through a nanopore: We consider the translocation dynamics of a polymer chain forced through a\nnanopore by an external force on its head monomer on the trans side. For a\nproper theoretical treatment we generalize the iso-flux tension propagation\n(IFTP) theory to include friction arising from the trans side subchain. The\ntheory reveals a complicated scenario of multiple scaling regimes depending on\nthe configurations of the cis and the trans side subchains. In the limit of\nhigh driving forces $f$ such that the trans subchain is strongly stretched, the\ntheory is in excellent agreement with molecular dynamics simulations and allows\nan exact analytic solution for the scaling of the translocation time ${\\tau}$\nas a function of the chain length $N_0$ and $f$. In this regime the asymptotic\nscaling exponents for ${\\tau} \\sim N_0^{\\alpha} f^{\\beta}$ are $\\alpha=2$, and\n$\\beta =-1$. The theory reveals significant correction-to-scaling terms arising\nfrom the cis side subchain and pore friction, which lead to a very slow\napproach to $\\alpha =2$ from below as a function of increasing $N_0$."
    },
    {
        "anchor": "Enhanced vector-based model for elastic bonds in solids: A model (further referred to as the enhanced vector-based model or EVM) for\nelastic bonds in solids, composed of bonded particles is presented. The model\ncan be applied for a description of elastic deformation of rocks, ceramics,\nconcrete, nanocomposites, aerogels and other materials with structural elements\ninteracting via forces and torques. A material is represented as a set of\nparticles (rigid bodies) connected by elastic bonds. Vectors rigidly connected\nwith particles are used for description of particles orientations. Simple\nexpression for potential energy of a bond is proposed. Corresponding forces and\ntorques are calculated. Parameters of the potential are related to\nlongitudinal, transverse (shear), bending, and torsional stiffnesses of the\nbond. It is shown that fitting parameters of the potential allows one to\nsatisfy any values of stiffnesses. Therefore, the model is applicable to bonds\nwith arbitrary length/thickness ratio. Bond stiffnesses are expressed in terms\nof geometrical and elastic properties of the bonds using three models:\nBernoulli-Euler beam, Timoshenko beam, and short elastic cylinder. An approach\nfor validation of numerical implementation of the model is presented.\nValidation is carried out by a comparison of numerical and analytical solutions\nof four test problems for a pair of bonded particles. Benchmark expressions for\nforces and torques in the case of pure tension/compression, shear, bending and\ntorsion of a single bond are derived. This approach allows one to minimize the\ntime required for a numerical implementation of the model.\n  Keywords: granular solid, elastic bond, torque interactions, V-model,\ndiscrete element method, distinct element method, particle dynamics.",
        "positive": "Transient Binding and Dissipation in Semi-flexible Polymer Networks: While polymer solutions lack the mechanical stability only transiently\ncross-linked networks can fulfill the competing requirements of structural\nstability and maximal energy dissipation. Here, we show that transient\ncross-links entail local stress relaxation and energy dissipation in an\nintermediate elasticity dominated frequency regime. We quantify the mechanical\nresponse of a semi-flexible polymer network by experimentally tuning the\noff-rate of the transient cross-linker molecule and theoretically reproduce the\nmeasured frequency response by a model that is predicated on microscopic\nunbinding events."
    },
    {
        "anchor": "Effect of interstitial fluid on the fraction of flow microstates that\n  precede clogging in granular hoppers: We report on the nature of flow events for the gravity-driven discharge of\nglass beads through a hole that is small enough that the hopper is susceptible\nto clogging. In particular, we measure the average and standard deviation of\nthe distribution of discharged masses as a function of both hole and grain\nsizes. We do so in air, which is usual, but also with the system entirely\nsubmerged under water. This damps the grain dynamics and could be expected to\ndramatically affect the distribution of the flow events, which are described in\nprior work as avalanche-like. Though the flow is slower and the events last\nlonger, we find that the average discharge mass is only slightly reduced for\nsubmerged grains. Furthermore, we find that the shape of the distribution\nremains exponential, implying that clogging is still a Poisson process even for\nimmersed grains. Per Thomas and Durian [Phys. Rev. Lett. 114, 178001 (2015]),\nthis allows interpretation of the average discharge mass in terms of the\nfraction of flow microstates that precede, i.e. that effectively cause, a\nstable clog to form. Since this fraction is barely altered by water, we\nconclude that the crucial microscopic variables are the grain positions; grain\nmomenta play only a secondary role in destabilizing weak incipient arches.\nThese insights should aid on-going efforts to understand the susceptibility of\ngranular hoppers to clogging.",
        "positive": "Flow of magnetic repelling grains in a two-dimensional silo: During a typical silo discharge, the material flow rate is determined by the\ncontact forces between the grains. Here, we report an original study concerning\nthe discharge of a two-dimensional silo filled with repelling magnetic grains.\nThis non-contact interaction leads to a different dynamics from the one\nobserved with conventional granular materials. We found that, although the flow\nrate dependence on the aperture size follows roughly the power-law with an\nexponent $3/2$ found in non-repulsive systems, the density and velocity\nprofiles during the discharge are totally different. New phenomena must be\ntaken into account. Despite the absence of contacts, clogging and intermittence\nwere also observed for apertures smaller than a critical size determined by the\neffective radius of the repulsive grains."
    },
    {
        "anchor": "Colloid-polymer mixtures in the protein limit: We computed the phase-separation behavior and effective interactions of\ncolloid-polymer mixtures in the \"protein limit\", where the polymer radius of\ngyration is much larger than the colloid radius. For ideal polymers, the\ncritical colloidal packing fraction tends to zero, whereas for interacting\npolymers in a good solvent the behavior is governed by a universal binodal,\nimplying a constant critical colloid packing fraction. In both systems the\ndepletion interaction is not well described by effective pair potentials but\nrequires the incorporation of many-body contributions.",
        "positive": "A semi-flexible attracting-segment model of three-dimensional polymer\n  collapse: Recently it has been shown that a two-dimensional model of self-attracting\npolymers based on attracting segments with the addition of stiffness displays\nthree phases: a swollen phase, a globular, liquid-like phase, and an\nanisotropic crystal-like phase. Here, we consider the attracting segment model\nin three dimensions with the addition of stiffness. While we again identify a\nswollen and two distinct collapsed phases, we find that both collapsed phases\nare anisotropic, so that there is no phase in which the polymer resembles a\ndisordered liquid drop. Moreover all the phase transitions are first order."
    },
    {
        "anchor": "Transporting Particles with Vortex Rings: Due to their long-lived nature, vortex rings are highly promising for\nnon-contact transportation of colloidal microparticles. However, they are\ncomplex structures, and their description using rigorous, closed-form\nmathematical expressions is challenging, particularly in the presence of\nstrongly inhomogeneous colloidal suspensions. This study presents\nstraightforward analytical approximations that reveal the dynamics of vortex\nrings transporting microparticles. Our results were validated using\ncomprehensive simulations and experimental measurements.",
        "positive": "Density Functional Theory of Inhomogeneous Liquids IV. Squared-gradient\n  approximation and Classical Nucleation Theory: The Squared-Gradient approximation to the Modified-Core Van der Waals density\nfunctional theory model is developed. A simple, explicit expression for the SGA\ncoefficient involving only the bulk equation of state and the interaction\npotential is given. The model is solved for planar interfaces and spherical\nclusters and is shown to be quantitatively accurate in comparisons to computer\nsimulations. An approximate technique for solving the SGA based on\npiecewise-linear density profiles is introduced and is shown to give reasonable\nzeroth-order approximations to the numerical solution of the model. The\npiecewise-linear models of spherical clusters are shown to be a natural\nextension of Classical Nucleation Theory and serve to clarify some of the\nnon-classical effects previously observed in liquid-vapor nucleation.\nNucleation pathways are investigated using both constrained energy-minimization\nand steepest-descent techniques."
    },
    {
        "anchor": "Theoretical estimation of density profile of semiflexible polymers\n  adsorbed on a surface and thermodynamic glass transition scenario by means of\n  the Bethe-Peierls approximation: We develop a theory describing density profile of the semi-flexible polymers\nabsorbed onto a planar surface. The theoretical analysis consists of two parts.\nAs a first part, we calculate a density profile of the adsorbed polymers by\ndeveloping an extension of the Bethe-Peierls approximation to the case of\nnonhomogeneous systems. This approach relies on the combination of the single\nchain adsorption theory and the lattice version of the self-consistent field\ntheory. Semi-flexibility of a chain is described by incorporating a finite\ncoordination number of the lattice into the consideration, in the spirit of the\nprevious Silberberg approach. The developed lattice theory incorporates the\ninteraction between nearest-neighbor pairs of segments and finite chain length.\nThe theory is completely mapped into the Scheutjens-Fleer theory in the limit\nof infinite coordination number. As a second part of the developed approach, we\ncalculate the configurational entropy to investigate how the density structure\nof the semi-flexible polymers near the surface relates to possible reduction of\nglass transition temperature near nonabsorbing surface and enhancement near the\nstrongly attractive surface.",
        "positive": "Holographic characterization and tracking of colloidal dimers in the\n  effective-sphere approximation: An in-line hologram of a colloidal sphere can be analyzed with the Lorenz-Mie\ntheory of light scattering to measure the sphere's three-dimensional position\nwith nanometer-scale precision while also measuring its diameter and refractive\nindex with part-per-thousand precision. Applying the same technique to\naspherical or inhomogeneous particles yields the position, diameter and\nrefractive index of an effective sphere that represents an average over the\nparticle's geometry and composition. This effective-sphere interpretation has\nbeen applied successfully to porous, dimpled and coated spheres, as well as to\nfractal clusters of nanoparticles, all of whose inhomogeneities appear on\nlength scales smaller than the wavelength of light. Here, we combine numerical\nand experimental studies to investigate effective-sphere characterization of\nsymmetric dimers of micrometer-scale spheres, a class of aspherical objects\nthat appear commonly in real-world dispersions. Our studies demonstrate that\nthe effective-sphere interpretation usefully identifies dimers in holographic\ncharacterization studies of monodisperse colloidal spheres. The\neffective-sphere estimate for a dimer's axial position closely follows the\nground truth for its center of mass. Trends in the effective-sphere diameter\nand refractive index, furthermore, can be used to measure a dimer's\nthree-dimensional orientation. When applied to colloidal dimers transported in\na Poiseuille flow, the estimated orientation distribution is consistent with\nexpectations for Brownian particles undergoing Jeffery orbits."
    },
    {
        "anchor": "Spatiotemporal correlations between plastic events in the shear flow of\n  athermal amorphous solids: The slow flow of amorphous solids exhibits striking heterogeneities: swift\nlocalised particle rearrangements take place in the midst of a more or less\nhomogeneously deforming medium. Recently, experimental as well as numerical\nwork has revealed spatial correlations between these flow heterogeneities.\nHere, we use molecular dynamics (MD) simulations to characterise the\nrearrangements and systematically probe their correlations both in time and in\nspace. In particular, these correlations display a four-fold azimuthal symmetry\ncharacteristic of shear stress redistribution in an elastic medium and we\nunambiguously detect their increase in range with time. With increasing shear\nrate, correlations become shorter-ranged and more isotropic. In addition, we\nstudy a coarse-grained model motivated by the observed flow characteristics and\nchallenge its predictions directly with the MD simulations. While the model\ncaptures both macroscopic and local properties rather satisfactorily, the\nagreement with respect to the spatiotemporal correlations is at most\nqualitative. The discrepancies provide important insight into relevant physics\nthat is missing in all related coarse-grained models that have been developed\nfor the flow of amorphous materials so far, namely the finite shear wave\nvelocity and the impact of elastic heterogeneities on stress redistribution.",
        "positive": "A Generalized Grand-Reaction Method for Modelling the Exchange of Weak\n  (Polyprotic) Acids between a Solution and a Weak Polyelectrolyte Phase: We introduce a Monte-Carlo method that allows for the simulation of a\npolymeric phase containing a weak polyelectrolyte, which is coupled to a\nreservoir at a fixed pH, salt concentration and total concentration of a weak\npolyprotic acid. The method generalizes the established Grand-Reaction Method\nby Landsgesell et al. [Macromolecules 53, 3007-3020 (2020)] and thus allows for\nthe simulation of polyelectrolyte systems coupled to reservoirs with a more\ncomplex chemical composition. In order to set the required input parameters\nthat correspond to a desired reservoir composition, we propose a generalization\nof the recently published chemical potential tuning algorithm of Miles et al.\n[Phys. Rev. E 105, 045311 (2022)]. To test the proposed tuning procedure, we\nperform extensive numerical tests for both ideal and interacting systems.\nFinally, as a showcase, we apply the method to a simple test system which\nconsists of a weak polybase solution that is coupled to a reservoir containing\na small diprotic acid. The complex interplay of the ionization various species,\nthe electrostatic interactions and the partitioning of small ions leads to a\nnon-monotonous, stepwise swelling behaviour of the weak polybase chains."
    },
    {
        "anchor": "Free energy of colloidal particles at the surface of sessile drops: The influence of finite system size on the free energy of a spherical\nparticle floating at the surface of a sessile droplet is studied both\nanalytically and numerically. In the special case that the contact angle at the\nsubstrate equals $\\pi/2$ a capillary analogue of the method of images is\napplied in order to calculate small deformations of the droplet shape if an\nexternal force is applied to the particle. The type of boundary conditions for\nthe droplet shape at the substrate determines the sign of the capillary\nmonopole associated with the image particle. Therefore, the free energy of the\nparticle, which is proportional to the interaction energy of the original\nparticle with its image, can be of either sign, too. The analytic solutions,\ngiven by the Green's function of the capillary equation, are constructed such\nthat the condition of the forces acting on the droplet being balanced and of\nthe volume constraint are fulfilled. Besides the known phenomena of attraction\nof a particle to a free contact line and repulsion from a pinned one, we\nobserve a local free energy minimum for the particle being located at the drop\napex or at an intermediate angle, respectively. This peculiarity can be traced\nback to a non-monotonic behavior of the Green's function, which reflects the\ninterplay between the deformations of the droplet shape and the volume\nconstraint.",
        "positive": "Many-particle hydrodynamic interactions in parallel-wall geometry:\n  Cartesian-representation method: This paper describes the results of our theoretical and numerical studies of\nhydrodynamic interactions in a suspension of spherical particles confined\nbetween two parallel planar walls, under creeping-flow conditions. We propose a\nnovel algorithm for accurate evaluation of the many-particle friction matrix in\nthis system--no such algorithm has been available so far.\n  Our approach involves expanding the fluid velocity field into spherical and\nCartesian fundamental sets of Stokes flows. The interaction of the fluid with\nthe particles is described using the spherical basis fields; the flow scattered\nwith the walls is expressed in terms of the Cartesian fundamental solutions. At\nthe core of our method are transformation relations between the spherical and\nCartesian basis sets. These transformations allow us to describe the flow field\nin a system that involves both the walls and particles.\n  We used our accurate numerical results to test the single-wall superposition\napproximation for the hydrodynamic friction matrix. The approximation yields\nfair results for quantities dominated by single particle contributions, but it\nfails to describe collective phenomena, such as a large transverse resistance\ncoefficient for linear arrays of spheres."
    },
    {
        "anchor": "Orientational ordering and phase behaviour of a binary mixture of hard\n  spheres and hard spherocylinders: We study structure and fluid-phase behaviour of a binary mixture of hard\nspheres (HSs) and hard spherocylinders (HSCs) in isotropic and nematic states\nusing the $NP_nAT$ ensemble Monte Carlo (MC) method in which a normal pressure\ntensor component is fixed in a system confined between two hard walls. The\nmethod allows one to estimate the location of the isotropic-nematic phase\ntransition and to observe the asymmetry in the composition between the\ncoexisting phases, with the expected increase of the HSC concentration in the\nnematic phase. This is in stark contrast with the previously reported MC\nsimulations where a conventional isotropic $NPT$ ensemble was used. We further\ncompare the simulation results with the theoretical predictions of two analytic\ntheories that extend the original Parsons-Lee theory using the one-fluid and\nthe many-fluid approximation [Malijevsk\\'y {\\it at al} J. Chem. Phys.\n\\textbf{129}, 144504 (2008)]. In the one-fluid version of the theory the\nproperties of the mixture are mapped on an effective one-component HS system\nwhile in the many-fluid theory the components of the mixtures are represented\nas separate effective HS particles. The comparison reveals that both the one-\nand the many-fluid approaches provide a reasonably accurate quantitative\ndescription of the mixture including the predictions of the isotropic-nematic\nphase boundary and degree of orientational order of the HSC-HS mixtures.",
        "positive": "On a new application of the path integrals in polymer statistical\n  physics: We propose a new approach based on the path integral formalism to the\ncalculation of the probability distribution functions of quadratic quantities\nof the Gaussian polymer chain in d-dimensional space, such as the radius of\ngyration and potential energy in the parabolic well. In both cases we obtain\nthe exact relations for the characteristic function and cumulants. Using the\nstandard steepest-descent method, we evaluate the probability distribution\nfunctions in two limiting cases of the large and small values of corresponding\nvariables."
    },
    {
        "anchor": "Surface tension in bilayer membranes with fixed projected area: We study the elastic response of bilayer membranes with fixed projected area\nto both stretching and shape deformations. A surface tension is associated to\neach of these deformations. By using model amphiphilic membranes and computer\nsimulations, we are able to observe both the types of deformation, and thus,\nboth the surface tensions, related to each type of deformation, are measured\nfor the same system. These surface tensions are found to assume different\nvalues in the same bilayer membrane: in particular they vanish for different\nvalues of the projected area. We introduce a simple theory which relates the\ntwo quantities and successfully apply it to the data obtained with computer\nsimulations.",
        "positive": "Evaporative Deposition Patterns Revisited: Spatial Dimensions of the\n  Deposit: A model accounting for finite spatial dimensions of the deposit patterns in\nthe evaporating sessile drops of colloidal solution on a plane substrate is\nproposed. The model is based on the assumption that the solute particles occupy\nfinite volume and hence these dimensions are of the steric origin. Within this\nmodel, the geometrical characteristics of the deposition patterns are found as\nfunctions of the initial concentration of the solute, the initial geometry of\nthe drop, and the time elapsed from the beginning of the drying process. The\nmodel is solved analytically for small initial concentrations of the solute and\nnumerically for arbitrary initial concentrations of the solute. The agreement\nbetween our theoretical results and the experimental data is demonstrated, and\nit is shown that the observed dependence of the deposit dimensions on the\nexperimental parameters can indeed be attributed to the finite dimensions of\nthe solute particles. These results are universal and do not depend on any free\nor fitting parameters; they are important for understanding the evaporative\ndeposition and may be useful for creating controlled deposition patterns."
    },
    {
        "anchor": "Analytic Solution of an Active Brownian Particle in a Harmonic Well: We provide an analytical solution for the time-dependent Fokker-Planck\nequation for a two-dimensional active Brownian particle trapped in an isotropic\nharmonic potential. Using the passive Brownian particle as basis states we show\nthat the Fokker-Planck operator becomes lower diagonal, implying that the\neigenvalues are unaffected by the activity. The propagator is then expressed as\na combination of the equilibrium eigenstates with weights obeying exact\niterative relations. We show that for the low-order correlation functions, such\nas the positional autocorrelation function, the recursion terminates at finite\norder in the P\\'eclet number allowing us to generate exact compact expressions\nand derive the velocity autocorrelation function and the time-dependent\ndiffusion coefficient. The nonmonotonic behavior of latter quantities serves as\na fingerprint of the non-equilibrium dynamics.",
        "positive": "Thermal Degradation of Adsorbed Bottle-Brush Macromolecules: Molecular\n  Dynamics Simulation: The scission kinetics of bottle-brush molecules in solution and on an\nadhesive substrate is modeled by means of Molecular Dynamics simulation with\nLangevin thermostat. Our macromolecules comprise a long flexible polymer\nbackbone with $L$ segments, consisting of breakable bonds, along with two side\nchains of length $N$, tethered to each segment of the backbone. In agreement\nwith recent experiments and theoretical predictions, we find that bond cleavage\nis significantly enhanced on a strongly attractive substrate even though the\nchemical nature of the bonds remains thereby unchanged.\n  We find that the mean bond life time $<\\tau>$ decreases upon adsorption by\nmore than an order of magnitude even for brush molecules with comparatively\nshort side chains $N=1 \\div 4$. The distribution of scission probability along\nthe bonds of the backbone is found to be rather sensitive regarding the\ninterplay between length and grafting density of side chains. The life time\n$<\\tau>$ declines with growing contour length $L$ as $<\\tau>\\propto L^{-0.17}$,\nand with side chain length as $<\\tau>\\propto N^{-0.53}$. The probability\ndistribution of fragment lengths at different times agrees well with\nexperimental observations. The variation of the mean length $L(t)$ of the\nfragments with elapsed time confirms the notion of the thermal degradation\nprocess as a first order reaction."
    },
    {
        "anchor": "Fold analysis of crumpled sheet using micro computed tomography: Hand crumpled paper balls involve intricate structure with a network of\ncreases and vertices, yet show simple scaling properties, which suggests\nself-similarity of the structure. We investigate the internal structure of\ncrumpled papers by the micro computed tomography (micro-CT) without destroying\nor unfolding them. From the reconstructed three dimensional data, we examine\nseveral power laws for the crumpled square sheets of paper of the sizes\n$L=50\\sim 300$ mm, and obtain the mass fractal dimension $D_M = 2.7\\pm 0.1$ by\nthe relation between the mass and the radius of gyration of the balls, and the\nfractal dimension $2.5\\lesssim d_f \\lesssim 2.8$ for the internal structure of\neach crumpled paper ball by the box counting method in the real space and the\nstructure factors in the Fourier space; The data for the paper sheets are\nconsistent with $D_M = d_f$, suggesting that the self-similarity in the\nstructure of each crumpled ball gives rise to the similarity among the balls\nwith different sizes. We also examine the cellophane sheets and the aluminium\nfoils of the size $L=200$ mm and obtain $2.6\\lesssim d_f\\lesssim 2.8$ for both\nof them. The micro-CT also allows us to reconstruct 3-d structure of a line\ndrawn on the crumpled sheets of paper. The Hurst exponent for the root mean\nsquare displacement along the line is estimated as $H\\approx 0.9$ for the\nlength scale shorter than the scale of the radius of gyration, beyond which the\nline structure becomes more random with $H\\sim 0.5$.",
        "positive": "Atomic Bose-Einstein Condensation with Three-Body Interactions and\n  Collective Excitations: The stability of a Bose-Einstein condensed state of trapped ultra-cold atoms\nis investigated under the assumption of an attractive two-body and a repulsive\nthree-body interaction. The Ginzburg-Pitaevskii-Gross (GPG) nonlinear\nSchr\\\"odinger equation is extended to include an effective potential dependent\non the square of the density and solved numerically for the s-wave. The lowest\nfrequency of the collective mode is determined and its dependences on the\nnumber of atoms and on the strength of the three-body force are studied. We\nshow that the addition of three-body dynamics can allow the number of condensed\natoms to increase considerably, even when the strength of the three-body force\nis very small compared with the strength of the two-body force. We also observe\na first-order liquid-gas phase transition for the condensed state up to a\ncritical strength of the effective three-body force."
    },
    {
        "anchor": "Unsteady flow and particle migration in dense, non-Brownian suspensions: We present experimental results on dense corn-starch suspensions as examples\nof non-Brownian, nearly-hard particles that undergo continuous and\ndiscontinuous shear thickening (CST and DST) at intermediate and high densities\nrespectively. Our results offer strong support for recent theories involving a\nstress-dependent effective contact friction among particles. We show however\nthat in the DST regime, where theory might lead one to expect steady-state\nshear bands oriented layerwise along the vorticity axis, the real flow is\nunsteady. To explain this, we argue that steady-state banding is generically\nruled out by the requirement that, for hard non-Brownian particles, the solvent\npressure and the normal-normal component of the particle stress must balance\nseparately across the interface between bands. (Otherwise there is an\nunbalanced migration flux.) However, long-lived transient shear-bands remain\npossible.",
        "positive": "Tilt or twist-competing synclinic and anticlinic interactions in SmC\n  phases of bent-core mesogens: Recent liquid-crystalline (LC) research is focused on structurally new\nmolecular systems distinct from simple nematic or smectic phases. Sophisticated\nmolecular shape may reveal structural complexity, combining helicity and\npolarity. Achiral symmetry-breaking in bent-core molecules leads to propensity\nfor synclinic and anticlinic molecular structures within consecutive smectic\nlayers. Moreover, despite their achiral character, dimers readily adopt helical\nphases. In our study, we investigated a hybrid molecular structure\nincorporating both characteristics, namely a rigid-bent core and an attached\nbulky polar group via a flexible spacer. To perform phase identification, we\nenriched the standard experimental methods with the sophisticated resonant soft\nx-ray scattering. Notably, we have observed a distinct preference for specific\nphase types depending on the length of the homologue. Longer homologues exhibit\na predisposition towards the formation of tilted smectic phases, characterized\nby complex sequences of synclinic and anticlinic interfaces. Conversely,\nshorter homologues manifest a propensity for helical smectic structures. For\nintermediate homologues, the frustration is alleviated through the formation of\nseveral modulated smectic phases. Based on the presented research, we describe\nthe preconditions for high level structures in relation with conflicting\nconstraints."
    },
    {
        "anchor": "Diffusion, mixing, and segregation in confined granular flows: Discrete element method simulations of confined bidisperse granular shear\nflows elucidate the balance between diffusion and segregation that can lead to\neither mixed or segregated states, depending on confining pressure. Results\nindicate that the collisional diffusion is essentially independent of\noverburden pressure. Because the rate of segregation diminishes with overburden\npressure, the tendency for particles to segregate weakens relative to the\nre-mixing of particles due to collisional diffusion as the overburden pressure\nincreases. Using a continuum approach that includes a pressure dependent\nsegregation velocity and a pressure independent diffusion coefficient, the\ninterplay between diffusion and segregation is accurately predicted for both\nsize and density bidisperse mixtures over a wide range of flow conditions when\ncompared to simulation results. Additional simulations with initially\nsegregated conditions demonstrate that applying a high enough overburden\npressure can suppress segregation to the point that collisional diffusion mixes\nthe segregated particles.",
        "positive": "Sol-gel transition by evaporation in porous media: Historical monuments, outdoor stone sculptures and artworks made of porous\nmaterials are exposed to chemical and physical degradation over time.\nPresently, the most promising route for consolidation of weakened porous\nmaterials is the injection of viscoelastic solutions of polymerizing compounds.\nThose compounds, after injection, undergo a sol-gel transition inside the\nporous media through evaporation of the solvent. Finding a suitable gelifying\nsolution as a consolidant calls for understanding the drying kinetics of\nviscoelastic fluids in porous media. Here, we present a multiscale study of the\ndrying kinetics of solutions during the sol-gel transition. We investigate the\ndrying dynamics and subsequent water uptake of a gel using NMR and X-ray\nmicrotomography techniques in porous materials. We find that during drying, a\ndistinct front develops which separates the liquid region from the gelled\nregion. This front advances from the free surface of evaporation towards the\ninner parts of the stone. We identify different drying periods which appear to\nbe dependent on the intrinsic properties of the porous medium influencing\nstrongly the homogeneity of the final gel distribution within a treated stone.\nOur findings not only are relevant for the consolidation of porous artworks but\nalso for civil and soil engineering processes where the fluids considered are\ngenerally more complex than water."
    },
    {
        "anchor": "From density to interface fluctuations: the origin of wavelength\n  dependence in surface tensions: The height-height correlation function for a fluctuating interface between\ntwo coexisting bulk phases is derived by means of general equilibrium\nproperties of the corresponding density-density correlation function. A\nwavelength-dependent surface tension $\\gamma(\\mathbf{q})$ can be defined and\nexpressed in terms of the direct correlation function\n$c(\\mathbf{r},\\mathbf{r}')$, the equilibrium density profile\n$\\rho_{\\circ}(\\mathbf{r})$ and an operator which relates density to surface\nconfigurations. Neither the concept of an effective interface Hamiltonian nor\nthe difference in pressure is needed to determine the general structure of the\nheight-height correlations or $\\gamma(\\mathbf{q})$, respectively. This result\ngeneralizes the Mecke/Dietrich surface tension $\\gmd$ (Phys. Rev. E {\\bf 59},\np. 6766 (1999)) and modifies recently published criticism concerning $\\gmd$ (P.\nTarazona, R. Checa and, E.Chac\\'{o}n: Phys. Rev. Lett. {\\bf 99}, p. 196101\n(2007)).",
        "positive": "Generation and propagation of solitary waves in nematic liquid crystals: Solitons in nematic liquid crystals offer intriguing opportunities for\ntransport and sensing in microfluidic systems. Little is known about the\nelementary conditions that are needed to create solitons in nematic materials.\nIn this work, theory, simulations and experiments are used to study the\ngeneration and propagation of solitary waves (or \"solitons\") in nematic liquid\ncrystals upon the application of an alternating current (AC) electric field. We\nfind that these solitary waves exhibit \"butterfly\"-like or \"bullet\"-like\nstructures that travel in the direction perpendicular to the applied electric\nfield. Such structures propagate over long distances without losing their\ninitial shape. The theoretical model adopted here serves to identify some of\nthe key requirements that are needed to generate solitons in the absence of\nelectrostatic interactions. These include surface imperfections that introduce\na twist in the director, unequal elastic constants, and negative anisotropic\ndielectric permittivity. The results of simulations are shown to be in good\nagreement with our own experimental observations, serving to establish the\nvalidity of the theoretical concepts advanced in this work."
    },
    {
        "anchor": "Thermal Breakage and Self-Healing of a Polymer Chain under Tensile\n  Stress: We consider the thermal breakage of a tethered polymer chain of discrete\nsegments coupled by Morse potentials under constant tensile stress. The chain\ndynamics at the onset of fracture is studied analytically by Kramers-Langer\nmultidimensional theory and by extensive Molecular Dynamics simulations in 1D-\nand 3D-space. Comparison with simulation data in one- and three dimensions\ndemonstrates that the Kramers-Langer theory provides good qualitative\ndescription of the process of bond-scission as caused by a {\\em collective}\nunstable mode. We derive distributions of the probability for scission over the\nsuccessive bonds along the chain which reveal the influence of chain ends on\nrupture in good agreement with theory. The breakage time distribution of an\nindividual bond is found to follow an exponential law as predicted by theory.\nSpecial attention is focused on the recombination (self-healing) of broken\nbonds. Theoretically derived expressions for the recombination time and\ndistance distributions comply with MD observations and indicate that the energy\nbarrier position crossing is not a good criterion for true rupture. It is shown\nthat the fraction of self-healing bonds increases with rising temperature and\nfriction.",
        "positive": "Understanding crack versus cavitation in pressure-sensitive adhesives:\n  the role of kinetics: We perform traction experiments on viscous liquids highly confined between\nparallel plates, a geometry known as the probe-tack test in the adhesion\ncommunity. Direct observation during the experiment coupled to force\nmeasurement shows the existence of several mechanisms for releasing the stress.\nBubble nucleation and instantaneous growth had been observed in a previous\nwork. Upon increasing further the traction velocity or the viscosity, the\nbubble growth is progressively delayed. At high velocities, cracks at the\ninterface between the plate and the liquid appear before the bubbles have grown\nto their full size. Bubbles and cracks are thus observed concomitantly. At even\nhigher velocities, cracks develop fully so early that the bubbles are not even\nvisible. We present a theoretical model that describes these regimes, using a\nMaxwell fluid as a model for the actual fluid, a highly viscous silicon oil. We\npresent the resulting phase diagramme for the different force peak regimes. The\npredictions are compatible with the data. Our results show that in addition to\ncavitation, interfacial cracks are encountered in a probe-tack traction test\nwith viscoelastic, \\emph{liquid} materials and not solely with viscoelastic\nsolids like adhesives."
    },
    {
        "anchor": "Spontaneous sense inversion in helical mesophases: We investigate the pitch sensitivity of cholesteric phases of helicoidal\npatchy cylinders as a generic model for chiral (bio-)polymers and helix-shaped\ncolloidal rods. The behaviour of the macroscopic cholesteric pitch is studied\nfrom microscopic principles by invoking a simple density functional theory\ngeneralised to accommodate weakly twisted director fields. Upon changing the\ndegree of alignment along the local helicoidal director we find that\ncholesteric phases exhibit a sudden sense inversion whereby the cholesteric\nphase changes from left- to right-handed and vice versa. Since the local\nalignment is governed by thermodynamic variables such as density, temperature\nor the amplitude of an external directional field such pitch sense inversions\ncan be expected in systems of helical mesogens of both thermotropic and\nlyotropic origin. We show that the spontaneous change of helical symmetry is a\ndirect consequence of an antagonistic effective torque between helical\nparticles with a certain prescribed internal helicity. The results may help\nopening up new routes towards precise control of the helical handedness of\nchiral assemblies by a judicious choice of external control parameters.",
        "positive": "Textural properties of dense granular pastes produced by kneading: The efficiency of supported catalysts depends on the porous microstructure of\ntheir solid support, which regulates mass transfer, exposure to the active\nphase, and mechanical strength. Here, we focus on the manufacturing of a\nspecific type of catalytic support, $\\gamma$-alumina extrudates, by a\nkneading-extrusion process. In this process, a paste is initially formed by\nblending and subsequently kneading a boehmite powder, an aluminum oxide\nhydroxide precursor of $\\gamma$-alumina, with various liquids before undergoing\nextrusion. The crucial step in this process is the kneading step, which allows\ncontrol over the textural and mechanical properties of the extrudate. The\npresent experimental study aims to measure the impact of the kneading step on\nboehmite pastes prepared using a pilot kneader. The pastes are obtained by\nmixing boehmite powder with an acid and a basic solution in a two-step process\nknown as peptization and neutralization. In this study, kneading is conducted\nat various mixing speeds and durations while monitoring the torque exerted by\nthe boehmite paste on the kneader blades. Moreover, samples are extracted from\nthe pilot kneader at various stages of the kneading process, and their textural\nproperties are determined by both nitrogen sorption and mercury intrusion\nporosimetry. Our findings show that, at fixed composition, the textural\nproperties of boehmite pastes are controlled by the overall deformation\naccumulated during kneading. Conversely, for a fixed accumulated deformation,\nthe pH sets the textural properties. Finally, we identify an empirical control\nparameter that captures the combined effects of pH and accumulated deformation\non the key textural attributes of boehmite pastes. These results set the stage\nfor a systematic design approach of boehmite-based catalyst supports."
    },
    {
        "anchor": "Vacancy-stabilized crystalline order in hard cubes: We examine the effect of vacancies on the phase behavior and structure of\nsystems consisting of hard cubes using event-driven molecular dynamics and\nMonte Carlo simulations. We find a first-order phase transition between a fluid\nand a simple cubic crystal phase that is stabilized by a surprisingly large\nnumber of vacancies, reaching a net vacancy concentration of ~6.4% near bulk\ncoexistence. Remarkably, we find that vacancies increase the positional order\nin the system. Finally, we show that the vacancies are delocalized and\ntherefore hard to detect.",
        "positive": "The influence of adsorbed atoms concentration on the temperature\n  coefficient of resonant frequency of the quasi-Rayleigh wave: Within the model of self-consistent connection of quasi-Rayleigh wave with\nadsorbed atoms, a method of constructing a new class of radiometric sensors of\nthe temperature and concentration of adsorbed atoms on the surface acoustic\nwaves is proposed. Based on the developed theory of the dispersion and acoustic\nmode width of a quasi-Rayleigh wave on the adsorbed surface of monocrystals\nwith a Zinc blende structure, the temperature coefficient of the resonant\nfrequency of the surface acoustic wave is calculated depending on the\ntemperature and on the concentration of adsorbed atoms."
    },
    {
        "anchor": "Folded Goursat surface and banana-shaped seedpod: Thin vegetal shells have recently been a significant source of inspiration\nfor the de\\text{sign} of smart materials and soft actuators. Herein is\npresented a novel analytical family of isometric deformations with folds,\ninspired by a banana-shaped seedpod, which converts a vertical closing into\neither an horizontal closing or an opening depending on the location of the\nfold. Similarly to the seedpod, optimum shapes for opening ease are the most\nelongated ones.",
        "positive": "Cis-Trans Dynamical Asymmetry in Driven Polymer Translocation: During polymer translocation driven by e.g. voltage drop across a nanopore,\nthe segments in the cis-side is incessantly pulled into the pore, which are\nthen pushed out of it into the trans-side. This pulling and pushing polymer\nsegments are described in the continuum level by nonlinear transport processes\nknown, respectively, as fast and slow diffusions. By matching solutions of both\nsides through the mass conservation across the pore, we provide a physical\nbasis for the cis and trans dynamical asymmetry, a feature repeatedly reported\nin recent numerical simulations. We then predict how the total driving force is\ndynamically allocated between cis (pulling) and trans (pushing) sides,\ndemonstrating that the trans-side event adds a finite-chain length effect to\nthe dynamical scaling, which may become substantial for weak force and/or high\npore friction cases."
    },
    {
        "anchor": "Colloidal test bed for universal dynamics of phase transitions: Confined colloids constitute an ideal platform to advance our understanding\nof universal dynamics in critical systems.",
        "positive": "Barrier-mediated predator-prey dynamics: The survival chance of a prey chased by a predator depends not only on their\nrelative speeds but importantly also on the local environment they have to\nface. For example, a wolf chasing a deer might take a long time to cross a\nriver which can quickly be crossed by the deer. Here, we propose a simple\npredator-prey model for a situation in which both the escaping prey and the\nchasing predator have to surmount an energetic barrier. Different\nbarrier-assisted states of catching or final escaping are classified and\nsuitable scaling laws separating these two states are derived. We discuss the\neffect of fluctuations on the catching times and determine states in which\ncatching or escaping is more likely. We further identify trapping or escaping\nstates which are determined by hydrodynamics and chemotactic interactions. Our\nresults are of importance for both microbes and self-propelled unanimate\nmicroparticles following each other by non-reciprocal interactions in\ninhomogeneous landscapes."
    },
    {
        "anchor": "Frustrated Self-Assembly of Non-Euclidean Crystals of Nanoparticles: Self-organized complex structures in nature, e.g. viral capsids, hierarchical\nbiopolymers, and bacterial flagella, offer efficiency, adaptability,\nrobustness, and multi-functionality. Can we program the self-assembly of\nthree-dimensional (3D) complex structures with simple building blocks, and\nreach similar or higher level of sophistication in engineered materials? Here\nwe present an analytic theory of tetrahedral nanoparticles (NPs)\nself-assembling in 3D space, where unavoidable geometrical frustration combined\nwith competing attractive and repulsive inter-particle interactions lead to\ncontrollable, high-yield, and enantiopure self-assembly of helicoidal ribbons.\nThis theory, based on crystal structures in non-Euclidean space, predicts\nmorphologies that exhibit qualitative agreement with experimental observations.\nWe expect that this theory will offer a general framework for the self-assembly\nof simple polyhedral building blocks into complex morphologies with new\nmaterial capabilities such as tunable optical activity, essential for multiple\nemerging technologies.",
        "positive": "Studies on electrostatic interactions of colloidal particles under\n  two-dimensional confinement: We study the effective electrostatic interactions between a pair of charged\ncolloidal particles without salt ions while the system is confined in two\ndimensions. In particular we use a simplified model to elucidate the effects of\nrotational fluctuations in counterion distribution. The results exhibit\neffective colloidal attractions under appropriate conditions. Meanwhile,\nlong-range repulsions persist over most of our studied cases. The repulsive\nforces arise from the fact that in two dimensions the charged colloids cannot\nbe perfectly screened by counterions, as the residual quadrupole moments\ncontribute to the repulsions at longer range. And by applying multiple\nexpansions we find that the attractive forces observed at short range are\nmainly contributed from electrostatic interactions among higher-order electric\nmoments. We argue that the scenario for attractive interactions discussed in\nthis work is applicable to systems of charged nanoparticles or colloidal\nsolutions with macroions."
    },
    {
        "anchor": "Reaching the ideal glass transition by aging polymer films: Searching for the ideal glass transition, we exploit the ability of glassy\npolymer films to explore low energy states in remarkably short time scales. We\nuse 30 nm thick polystyrene (PS) films, which in the supercooled state\nbasically display the bulk polymer equilibrium thermodynamics and dynamics. We\nshow that in the glassy state, this system exhibits two mechanisms of\nequilibrium recovery. The faster one, active well below the kinetic glass\ntransition temperature ($T_g$), allows massive enthalpy recovery. This implies\nthat the 'fictive' temperature ($T_f$) reaches values as low as the predicted\nKauzmann temperature ($T_K$) for PS. Once the thermodynamic state corresponding\nto $T_f = T_K$ is reached, no further decrease of enthalpy is observed. This is\ninterpreted as a signature of the ideal glass transition.",
        "positive": "The mode-coupling glass transition in a fluid confined by a periodic\n  potential: We show that a fluid under strong spatially periodic confinement displays a\nglass transition within mode-coupling theory (MCT) at a much lower density than\nthe corresponding bulk system. We use fluctuating hydrodynamics, with\nconfinement imposed through a periodic potential whose wavelength plays an\nimportant role in our treatment. To make the calculation tractable we implement\na detailed calculation in one dimension. Although we do not expect simple 1d\nfluids to show a glass transition, our results are indicative of the behaviour\nexpected in higher dimensions. In a certain region of parameter space we\nobserve a three-step relaxation reported recently in computer simulations [S.H.\nKrishnan, PhD thesis, Indian Institute of Science (2005); Kim et al., Eur.\nPhys. J-ST 189, 135-139 (2010)] and a glass-glass transition. We compare our\nresults to those of Krakoviack, PRE 75, 031503 (2007) and Lang et al., PRL 105,\n125701 (2010)."
    },
    {
        "anchor": "Spinodal dewetting of thin films with large interfacial slip:\n  implications from the dispersion relation: We compare the dispersion relations for spinodally dewetting thin liquid\nfilms for increasing magnitude of interfacial slip length in the lubrication\nlimit. While the shape of the dispersion relation, in particular the position\nof the maximum, are equal for no-slip up to moderate slip lengths, the position\nof the maximum shifts to much larger wavelengths for large slip lengths. Here,\nwe discuss the implications of this fact for recently developed methods to\nassess the disjoining pressure in spinodally unstable thin films by measuring\nthe shape of the roughness power spectrum. For PS films on OTS covered Si\nwafers (with slip length b approx. 1 mum) we predict a 20% shift of the\nposition of the maximum of the power spectrum which should be detectable in\nexperiments.",
        "positive": "First-principles derivation of density functional formalism for\n  quenched-annealed systems: We derive from first principles (without resorting to the replica trick) a\ndensity functional theory for fluids in quenched disordered matrices (QA-DFT).\nWe show that the disorder-averaged free energy of the fluid is a functional of\nthe average density profile of the fluid as well as the pair correlation of the\nfluid and matrix particles. For practical reasons it is preferable to use\nanother functional: the disorder-averaged free energy plus the fluid-matrix\ninteraction energy, which, for fixed fluid-matrix interaction potential, is a\nfunctional only of the average density profile of the fluid. When the matrix is\ncreated as a quenched configuration of another fluid, the functional can be\nregarded as depending on the density profile of the matrix fluid as well. In\nthis situation, the replica-Ornstein-Zernike equations which do not contain the\nblocking parts of the correlations can be obtained as functional identities in\nthis formalism, provided the second derivative of this functional is\ninterpreted as the connected part of the direct correlation function. The\nblocking correlations are totally absent from QA-DFT, but nevertheless the\nthermodynamics can be entirely obtained from the functional. We apply the\nformalism to obtain the exact functional for an ideal fluid in an arbitrary\nmatrix, and discuss possible approximations for non-ideal fluids."
    },
    {
        "anchor": "The Yield-Strain and Shear-Band Direction in Amorphous Solids Under\n  General Loading: It is well known experimentally that well-quenched amorphous solids exhibit a\nplastic instability in the form of a catastrophic shear localization at a well\ndefined value of the external strain. The instability may develop to a\nshear-band that in some cases is followed by a fracture. It is also known that\nthe values of the yield-strain (and yield-stress), as well as the direction of\nthe shear band with respect to the principal stress axis, vary considerably\nwith variations in the external loading conditions. In this paper we present a\nmicroscopic theory of these phenomena for 2-dimensional athermal amorphous\nsolids that are strained quasi-statically. We present analytic formulae for the\nyield-strains for different loading conditions, and well as for the angles of\nthe shear bands. We explain that the external loading conditions determine the\neigenvalues of the quadrupolar Eshelby inclusions which model the non-affine\ndisplacement field. These inclusions model elementary plastic events and\ndetermine both the yield-strain and the direction of the shear-band. We show\nthat the angles of the shear bands with respect to the principal stress axis\nare limited theoretically between $30^o$ and $60^o$. Available experimental\ndata conform to this prediction.",
        "positive": "Emergence of odd elasticity in a microswimmer using deep reinforcement\n  learning: We investigate the emergence of odd elasticity in an elastic microswimmer\nmodel by using Deep Q-Network with a reinforcement learning method. Although\nthe swimming velocity decreases for an elastic microswimmer with prescribed\ndynamics in the large-frequency regime, the fully trained elastic microswimmer\nadapts a waiting strategy to avoid the velocity decrease. For the trained\nmicroswimmers, we evaluate the performance of the cycles by the product of the\nloop area (called non-reciprocality) and the loop frequency, and show that the\naverage swimming velocity is proportional to the performance. By calculating\nthe force-displacement correlations, we obtain the effective odd elasticity of\nthe microswimmer to characterize its non-reciprocal dynamics. The emergent odd\nelasticity is closely related to the loop frequency of the cyclic deformation.\nThe present work provides us with a clue to reveal the emergence of various\nnon-reciprocal phenomena in active systems by using machine learning."
    },
    {
        "anchor": "High Strain and Strain-Rate Behaviour of PTFE/Aluminium/Tungsten\n  Mixtures: Conventional drop-weight techniques were modified to accommodate\nlow-amplitude force transducer signals from low-strength, cold isostatically\npressed 'heavy' composites of polytetrafluoroethylene, aluminum and tungsten.\nThe failure strength, strain and the post-critical behavior of failed samples\nwere measured for samples of different porosity and tungsten grain size.\nUnusual phenomenon of significantly higher strength (55 MPa) of porous\ncomposites (density 5.9 g/cc) with small W particles (less than 1 micron) in\ncomparison with strength (32 MPa) of dense composites (7.1 g/cc) with larger W\nparticles (44 microns) at the same volume content of components was observed.\nThis is attributed to force chains created by a network of small W particles.\nInterrupted tests at different levels of strain revealed the mechanisms of\nfracture under dynamic compression.",
        "positive": "Simulations of driven overdamped frictionless hard spheres: We introduce an event-driven simulation scheme for overdamped dynamics of\nfrictionless hard spheres subjected to external forces, neglecting hydrodynamic\ninteractions. Our event-driven approach is based on an exact equation of motion\nwhich relates the driving force to the resulting velocities through the\ngeometric information characterizing the underlying network of contacts between\nthe hard spheres. Our method allows for a robust extraction of the\ninstantaneous coordination of the particles as well as contact force statistics\nand dynamics, under any chosen driving force, in addition to shear flow and\ncompression. It can also be used for generating high-precision jammed packings\nunder shear, compression, or both. We present a number of additional\napplications of our method."
    },
    {
        "anchor": "Prediction and control of slip-free rotation states in sphere assemblies: We study fixed assemblies of touching spheres that can individually rotate.\nFrom any initial state, sliding friction drives an assembly toward a slip-free\nrotation state. For bipartite assemblies, which have only even loops, this\nstate has at least four degrees of freedom. For exactly four degrees of\nfreedom, we analytically predict the final state, which we prove to be\nindependent of the strength of sliding friction, from an arbitrary initial one.\nWith a tabletop experiment, we show how to impose any slip-free rotation state\nby only controlling two spheres, regardless of the total number.",
        "positive": "Many particle entanglement in two-component Bose-Einstein Condensates: We investigate schemes to dynamically create many particle entangled states\nof a two component Bose-Einstein condensate in a very short time proportional\nto 1/N where $N$ is the number of condensate particles. For small $N$ we\ncompare exact numerical calculations with analytical semiclassical estimates\nand find very good agreement for $N \\geq 50$. We also estimate the effect of\ndecoherence on our scheme, study possible scenarios for measuring the entangled\nstates, and investigate experimental imperfections."
    },
    {
        "anchor": "Mobile linkers on DNA-coated colloids: valency without patches: Colloids coated with single-stranded DNA (ssDNA) can bind selectively to\nother colloids coated with complementary ssDNA. The fact that DNA-coated\ncolloids (DNACCs) can bind to specific partners opens the prospect of making\ncolloidal `molecules'. However, in order to design DNACC-based molecules, we\nmust be able to control the valency of the colloids, i.e. the number of\npartners to which a given DNACC can bind. One obvious, but not very simple\napproach is to decorate the colloidal surface with patches of single-stranded\nDNA that selectively bind those on other colloids. Here we propose a design\nprinciple that exploits many-body effects to control the valency of otherwise\nisotropic colloids. Using a combination of theory and simulation, we show that\nwe can tune the valency of colloids coated with mobile ssDNA, simply by tuning\nthe non-specific repulsion between the particles. Our simulations show that the\nresulting effective interactions lead to low-valency colloids self-assembling\nin peculiar open structures, very different from those observed in DNACCs with\nimmobile DNA linkers.",
        "positive": "Phase diagram of diblock polyampholyte solutions: We discuss in this paper the phase diagram of a diblock polyampholyte\nsolution in the limit of high ionic strength as a function of concentration and\ncharge asymmetry. This system is shown to be very similar to solutions of\nso-called charged-neutral diblock copolymers: at zero charge asymmetry the\nsolution phase separates into a polyelectrolyte complex and almost pure\nsolvent. Above a charge asymmetry threshold, the copolymers are soluble as\nfinite size aggregates. Scaling laws of the aggregates radius as a function of\npH of the solution are in qualitative agreement with experiments."
    },
    {
        "anchor": "Geometric interpretation of pre-vitrification in hard sphere liquids: We derive a microscopic criterion for the stability of hard sphere\nconfigurations, and we show empirically that this criterion is marginally\nsatisfied in the glass. This observation supports a geometric interpretation\nfor the initial rapid rise of viscosity with packing fraction, or\npre-vitrification. It also implies that barely stable soft modes characterize\nthe glass structure, whose spatial extension is estimated. We show that both\nthe short-term dynamics and activation processes occur mostly along those soft\nmodes, and we study some implications of these observations. This article\nsynthesizes new and previous results [C. Brito and M. Wyart, Euro. Phys.\nLetters, {\\bf 76}, 149-155, (2006) and C. Brito and M. Wyart, J. Stat. Mech.,\nL08003 (2007) ] in a unified view.",
        "positive": "Avalanche localization and crossover scaling in amorphous plasticity: We perform large scale simulations of a two dimensional lattice model for\namorphous plasticity with random local yield stresses and long-range\nquadrupolar elastic interactions. We show that as the external stress increases\ntowards the yielding phase transition, the scaling behavior of the avalanches\ncrosses over from mean-field theory to a different universality class. This\nbehavior is associated with strain localization, which significantly depends on\nthe short-range properties of the interaction kernel."
    },
    {
        "anchor": "Scaling of Rough Surfaces: Effects of Surface Diffusion on Growth and\n  Roughness Exponents: Random deposition model with surface diffusion over several next nearest\nneighbours is studied. The results agree with the results obtained by Family\nfor the case of nearest neighbour diffusion [F. Family, J. Phys. A 19(8), L441,\n1986]. However for larger diffusion steps, the growth exponent and the\nroughness exponent show interesting dependence on diffusion length.",
        "positive": "Controlling phase separation in microgel-polymeric micelle mixtures\n  using variable quench rates: We investigate the temperature dependent phase behaviour of mixtures of\npoly(Nisopropylacrylamide) (pNIPAM) microgel colloids and a triblock copolymer\n(PEO-PPO-PEO) surfactant, which undergoes micellisation. Gelation in these\nsystems results from an increase in temperature. Here we alter the heating rate\nand observe that the mechanism for aggregation changes from one of depletion of\nthe microgels by the micelles at low temperatures to association of the two\nspecies at high temperatures. We use this to access multiple structures at one\nmicrogel concentration. Samples with a micelle concentration above 7 wt% were\nfound to demix into phases rich and poor in microgel particles at temperatures\nbelow 33 degrees, under conditions where the microgels particles are partially\nswollen. Under rapid heating full demixing is bypassed and gel networks are\nformed instead. The temperature history of the sample therefore allows for\nkinetic selection between different final structures, which may be metastable."
    },
    {
        "anchor": "Mean-Field Theory of Inhomogeneous Fluids: The Barker-Henderson perturbation theory is a bedrock of liquid-state\nphysics, providing quantitative predictions for the bulk thermodynamic\nproperties of realistic model systems. However, this successful method has not\nbeen exploited for the study of inhomogeneous systems. We develop and implement\na first-principles 'Barker-Henderson density functional', thus providing a\nrobust and quantitatively accurate theory for classical fluids in external\nfields. Numerical results are presented for the hard-core Yukawa model in three\ndimensions. Our predictions for the density around a fixed test particle and\nbetween planar walls are in very good agreement with simulation data. The\ndensity profiles for the free liquid vapour interface show the expected\noscillatory decay into the bulk liquid as the temperature is reduced towards\nthe triple point, but with an amplitude much smaller than that predicted by the\nstandard mean-field density functional.",
        "positive": "Cage Length Controls the Non-Monotonic Dynamics of Active Glassy Matter: Dense active matter is gaining widespread interest due to its remarkable\nsimilarity with conventional glass-forming materials. However, active matter is\ninherently out-of-equilibrium and even simple models such as active Brownian\nparticles (ABPs) and active Ornstein-Uhlenbeck particles (AOUPs) behave\nmarkedly differently from their passive counterparts. Controversially, this\ndifference has been shown to manifest itself via either a speedup, slowdown, or\nnon-monotonic change of the glassy relaxation dynamics. Here we rationalize\nthese seemingly contrasting views on the departure from equilibrium by\nidentifying the ratio of the short-time length scale to the cage length, i.e.\nthe length scale of local particle caging, as a vital and unifying control\nparameter for active glassy matter. In particular, we explore the glassy\ndynamics of both thermal and athermal ABPs and AOUPs upon increasing the\npersistence time. We find that for all studied systems there is an optimum of\nthe dynamics; this optimum occurs when the cage length coincides with the\ncorresponding short-time length scale of the system, which is either the\npersistence length for athermal systems or a combination of the persistence\nlength and a diffusive length scale for thermal systems. This new insight, for\nwhich we also provide a simple physical argument, allows us to reconcile and\nexplain the manifestly disparate departures from equilibrium reported in many\nprevious studies of dense active materials."
    },
    {
        "anchor": "Levitation by a dipole electric field: The phenomenon of floating can be fascinating in any field, with its presence\nseen in art, films, and scientific research. This phenomenon is a captivating\nand pertinent subject with practical applications, such as Penning traps for\nantimatter confinement and Ion traps as essential architectures for quantum\ncomputing models. In our project, we reproduced the 1893 water bridge\nexperiment using glycerol and first observed that lump-like macroscopic dipole\nmoments can undergo near-periodic oscillations that exhibit floating effects\nand do not need classical bridge form. By combining experimental analysis,\nneural networks, investigation of Kelvin force generated by the Finite element\nmethod, and exploration of discharging, we gain insights into the mechanisms of\nmotion. Our discovery has overturned the previous impression of a bridge\nfloating in the water, leading to a deeper understanding of the new trap\nmechanism under strong electric fields with a single pair of electrodes.",
        "positive": "Solvent Mediated Assembly of Nanoparticles Confined in Mesoporous\n  Alumina: The controlled self-assembly of thiol stabilized gold nanocrystals in a\nmediating solvent and confined within mesoporous alumina was probed in situ\nwith small angle x-ray scattering. The evolution of the self-assembly process\nwas controlled reversibly via regulated changes in the amount of solvent\ncondensed from an undersaturated vapor. Analysis indicated that the\nnanoparticles self-assembled into cylindrical monolayers within the porous\ntemplate. Nanoparticle nearest-neighbor separation within the monolayer\nincreased and the ordering decreased with the controlled addition of solvent.\nThe process was reversible with the removal of solvent. Isotropic clusters of\nnanoparticles were also observed to form temporarily during desorption of the\nliquid solvent and disappeared upon complete removal of liquid. Measurements of\nthe absorption and desorption of the solvent showed strong hysteresis upon\nthermal cycling. In addition, the capillary filling transition for the solvent\nin the nanoparticle-doped pores was shifted to larger chemical potential,\nrelative to the liquid/vapor coexistence, by a factor of 4 as compared to the\nexpected value for the same system without nanoparticles."
    },
    {
        "anchor": "Controlling Polymer Capture and Translocation by Electrostatic\n  Polymer-Pore Interactions: Polymer translocation experiments typically involve anionic polyelectrolytes\nsuch as DNA molecules driven through negatively charged nanopores. Quantitative\nmodelling of polymer capture to the nanopore followed by translocation\ntherefore necessitates the consideration of the electrostatic barrier resulting\nfrom like-charge polymer-pore interactions. To this end, in this work we couple\nmean-field level electrohydrodynamic equations with the Smoluchowski formalism\nto characterize the interplay between the electrostatic barrier, the\nelectrophoretic drift, and the electro-osmotic liquid flow. In particular, we\nfind that due to distinct ion density regimes where the salt screening of the\ndrift and barrier effects occur, there exists a characteristic salt\nconcentration maximizing the probability of barrier-limited polymer capture\ninto the pore. We also show that in the barrier-dominated regime, the polymer\ntranslocation time increases exponentially with the membrane charge and decays\nexponentially fast with the pore radius and the salt concentration. These\nresults suggest that the alteration of these parameters in the barrier-driven\nregime can be an efficient way to control the duration of the translocation\nprocess and facilitate more accurate measurements of the ionic current signal\nin the pore.",
        "positive": "Viscoelasticity and Rheological Hysteresis: Rheological characterization of complex fluids subjected to cyclic shear-rate\nsweep often exhibits hysteresis. Since both viscoelastic and thixotropic\nmaterials show hysteresis loops, it is important to understand distinguishing\nfeatures (if any) in the same shown by either. Lately, there has been\nsubstantial work that attempts to relate the area enclosed by the hysteresis\nloop with the manner in which shear rate is varied in the cycle, in order to\ninfer thixotropic parameters of a material. In this work, we use the nonlinear\nGiesekus model to study its response to the application of cyclic shear-rate\nsweep. We find that this model produces each type of ualitatively similar\nhysteresis loop that has hitherto been ascribed to thixotropic materials. We\nalso show that the area of the hysteresis loop for a viscoelastic material as a\nfunction of sweep rate shows bell-shaped/bi-modal curves as has been observed\nfor thixotropic materials. This study illustrates that caution needs to be\nexercised while attributing hysteresis loops and associated features observed\nin a material exclusively to thixotropy. Another feature related to the\nhysteresis loop is the occurrence of shear banding instability. We find that\nviscoelastic hysteresis may not have any connection to shear banding\ninstability."
    },
    {
        "anchor": "Frequency response in surface-potential driven electro-hydrodynamics: Using a Fourier approach we offer a general solution to calculations of slip\nvelocity within the circuit description of the electro-hydrodynamics in a\nbinary electrolyte confined by a plane surface with a modulated surface\npotential. We consider the case with a spatially constant intrinsic surface\ncapacitance where the net flow rate is in general zero while harmonic rolls as\nwell as time-averaged vortex-like components may exist depending on the spatial\nsymmetry and extension of the surface potential. In general the system displays\na resonance behavior at a frequency corresponding to the inverse RC time of the\nsystem. Different surface potentials share the common feature that the\nresonance frequency is inversely proportional to the characteristic length\nscale of the surface potential. For the asymptotic frequency dependence above\nresonance we find a 1/omega^2 power law for surface potentials with either an\neven or an odd symmetry. Below resonance we also find a power law omega^alpha\nwith alpha being positive and dependent of the properties of the surface\npotential. Comparing a tanh potential and a sech potential we qualitatively\nfind the same slip velocity, but for the below-resonance frequency response the\ntwo potentials display different power law asymptotics with alpha=1 and\nalpha~2, respectively.",
        "positive": "Self-Organization of Self-Clearing Beating Patterns in an Array of\n  Locally Interacting Ciliated Cells Formulated as an Adaptive Boolean Network: The observed spatio-temporal ciliary beat patterns on multiciliated epithelia\nare suspected to be the result of self-organizing processes on various levels.\nHere, we present an abstract epithelium model at the pluricellular level, which\nintends to make the self-organization of ciliary beating patterns as well as of\nthe associated fluid transport across the airway epithelium plausible. Ciliated\ncells are modeled in terms of locally interacting oscillating two-state\nactuators. The local interactions among these boolean actuators are triggered\nby seeded mucus lumps. In the course of a simulation the actuators' state and\nthe associated mucus velocity field self-organize in tandem. We suggest to\nconsider the dynamics on multiciliated epithelia in the context of adaptive\n(boolean) networks. Within the framework of adaptive boolean networks ciliated\ncells represent the nodes and as the mucus establishes the local interactions\namong nodes, its distribution determines the topology of the network.\nFurthermore, we present the results and insights from comprehensive parameter\nstudies. The results show evidence that so called deterministic update schemes,\nwhich are meant to represent intercellular signaling, lead to more realistic\nand robust dynamics and may therefore be favored by nature. Finally, we suppose\nthat unciliated cells introduce a modular network topology on ciliated\nepithelia causing the self-organization taking place simultaneously in each\n\"ciliated module\". This reasoning provides the first consistent explanation for\nthe meaning of the observed patchy expression patterns of the mucus modulation\nwave fields. Modularity may therefore be seen as a modular construction plan of\nnature for ciliated epithelia whose number of cells range over several order of\nmagnitudes."
    },
    {
        "anchor": "The role of the extra cellular matrix on memory: We expose first a biological model of memory based on one hand of the\nmechanical oscillations of axons during action potential and on the other hand\non the changes in the extra cellular matrix composition when a mechanical\nstrain is applied on it. Due to these changes, the stiffness of the extra\ncellular matrix along the most excited neurons will increase close to these\nneurons due to the growth of astrocytes around them and to the elastoplastic\nbehavior of collagen. This will create preferential paths linked to a memory\neffect. In a second part, we expose a physical model based on random walk of\nthe action potential on the array composed of dendrites and axons. This last\nmodel shows that repetition of the same event leads to long time memory of this\nevent and that paradoxical sleep leads to the linking of different events put\ninto memory.",
        "positive": "Wrinkling and multiplicity in the dynamics of deformable sheets in\n  uniaxial extensional flow: The processing of thin-structured materials in a fluidic environment, from\nnearly inextensible but flexible graphene sheets to highly extensible polymer\nfilms, arises in many applications. So far, little is known about the dynamics\nof such thin sheets freely suspended in fluid. In this work, we study the\ndynamics of freely suspended soft sheets in uniaxial extensional flow. Elastic\nsheets are modeled with a continuum model that accounts for in-plane\ndeformation and out-of-plane bending, and the fluid motion is computed using\nthe method of regularized Stokeslets. We explore two types of sheets: \"stiff\"\nsheets that strongly resist bending deformations and always stay flat, and\n\"flexible\" sheets with both in-plane and out-of plane deformability that can\nwrinkle. For stiff sheets, we observe a coil-stretch-like transition, similar\nto what has been observed for long-chain linear polymers under extension as\nwell as elastic sheets under planar extension: in a certain range of capillary\nnumber (flow strength relative to in-plane deformability), the sheets exhibit\neither a compact or a highly stretched conformation, depending on deformation\nhistory. For flexible sheets, sheets with sufficiently small bending stiffness\nwrinkle to form various conformations. Here, the compact-stretched bistability\nstill occurs, but is strongly modified by the wrinkling instability: a\nhighly-stretched planar state can become unstable and wrinkle, after which it\nmay dramatically shrink in length due to hydrodynamic screening associated with\nwrinkling. Therefore, wrinkling renders a shift in the bistability regime. In\naddition, we can predict and understand the nonlinear long-term dynamics for\nsome parameter regimes with linear stability analysis of the flat steady\nstates."
    },
    {
        "anchor": "Elastometry of Deflated Capsules: Elastic Moduli from Shape and Wrinkle\n  Analysis: Elastic capsules, prepared from droplets or bubbles attached to a capillary\n(as in a pendant drop tensiometer), can be deflated by suction through the\ncapillary. We study this deflation and show that a combined analysis of the\nshape and wrinkling characteristics enables us to determine the elastic\nproperties in situ. Shape contours are analyzed and fitted using shape\nequations derived from nonlinear membrane-shell theory to give the elastic\nmodulus, Poisson ratio and stress distribution of the membrane. We include\nwrinkles, which generically form upon deflation, within the shape analysis.\nMeasuring the wavelength of wrinkles and using the calculated stress\ndistribution gives the bending stiffness of the membrane. We compare this\nmethod with previous approaches using the Laplace-Young equation and illustrate\nthe method on two very different capsule materials: polymerized\noctadecyltrichlorosilane (OTS) capsules and hydrophobin (HFBII) coated bubbles.\nOur results are in agreement with the available rheological data. For\nhydrophobin coated bubbles the method reveals an interesting nonlinear behavior\nconsistent with the hydrophobin molecules having a rigid core surrounded by a\nsofter shell.",
        "positive": "Twisting short dsDNA with applied tension: The twisting deformation of mechanically stretched DNA molecules is studied\nby a coarse grained Hamiltonian model incorporating the fundamental\ninteractions that stabilize the double helix and accounting for the radial and\nangular base pair fluctuations. The latter are all the more important at short\nlength scales in which DNA fragments maintain an intrinsic flexibility. The\npresented computational method simulates a broad ensemble of possible molecule\nconformations characterized by a specific average twist and determines the\nenergetically most convenient helical twist by free energy minimization. As\nthis is done for any external load, the method yields the characteristic\ntwist-stretch profile of the molecule and also computes the changes in the\nmacroscopic helix parameters i.e. average diameter and rise distance. It is\npredicted that short molecules under stretching should first over-twist and\nthen untwist by increasing the external load. Moreover, applying a constant\nload and simulating a torsional strain which over-twists the helix, it is found\nthat the average helix diameter shrinks while the molecule elongates, in\nagreement with the experimental trend observed in kilo-base long sequences. The\nquantitative relation between percent relative elongation and superhelical\ndensity at fixed load is derived. The proposed theoretical model and\ncomputational method offer a general approach to characterize specific DNA\nfragments and predict their macroscopic elastic response as a function of the\neffective potential parameters of the mesoscopic Hamiltonian."
    },
    {
        "anchor": "Diffusion to capture and the concept of diffusive interactions: Diffusion to capture is an ubiquitous phenomenon in many fields in biology\nand physical chemistry, with implications as diverse as ligand-receptor binding\non eukaryotic and bacterial cells, nutrient uptake by colonies of unicellular\norganisms and the functioning of complex core-shell nanoreactors. Whenever many\nboundaries compete for the same diffusing molecules, they inevitably shield a\nvariable part of the molecular flux from each other. This gives rise to the\nso-called diffusive interactions (DI), which can reduce substantially the\ninflux to a collection of reactive boundaries depending chiefly on their\ngeometrical configuration. In this review we provide a pedagogical discussion\nof the main mathematical aspects underlying a rigorous account of DIs. Starting\nfrom a striking and deep result on the mean-field description of ligand binding\nto a receptor-covered cell, we develop little by little a rigorous mathematical\ndescription of DIs in the stationary case through the use of translational\naddition theorems for spherical harmonics. We provide several enlightening\nillustrations of this powerful mathematical theory, including diffusion to\ncapture to ensembles of reactive boundaries within a spherical cavity.",
        "positive": "Aspects of the dynamics of colloidal suspensions: Further results of the\n  mode-coupling theory of structural relaxation: Results of the idealized mode-coupling theory for the structural relaxation\nin suspensions of hard-sphere colloidal particles are presented and discussed\nwith regard to recent light scattering experiments. The structural relaxation\nbecomes non-diffusive for long times, contrary to the expectation based on the\nde Gennes narrowing concept. A semi-quantitative connection of the wave vector\ndependences of the relaxation times and amplitudes of the final\n$\\alpha$-relaxation explains the approximate scaling observed by Segr{\\`e} and\nPusey [Phys. Rev. Lett. {\\bf 77}, 771 (1996)]. Asymptotic expansions lead to a\nqualitative understanding of density dependences in generalized Stokes-Einstein\nrelations. This relation is also generalized to non-zero frequencies thereby\nyielding support for a reasoning by Mason and Weitz [Phys. Rev. Lett {\\bf 74},\n1250 (1995)]. The dynamics transient to the structural relaxation is discussed\nwith models incorporating short-time diffusion and hydrodynamic interactions\nfor short times."
    },
    {
        "anchor": "Sound emission due to superfluid vortex reconnections: By performing numerical simulations of superfluid vortex ring collisions we\nmake direct quantitative measurements of the sound energy released due to\nvortex reconnections. We show that the energy radiated expressed in terms of\nthe loss of vortex line length is a simple function of the reconnection angle.\nIn addition, we study the temporal and spatial distribution of the radiation\nand show that energy is emitted in the form of a rarefaction pulse. The pulse\nevolves into a sound wave with a wavelength of 6-8 healing lengths.",
        "positive": "Computing bulk and shear viscosities from simulations of fluids with\n  dissipative and stochastic interactions: Exact values for bulk and shear viscosity are important to characterize a\nfluid and they are a necessary input for a continuum description. Here we\npresent two novel methods to compute bulk viscosities by non-equilibrium\nmolecular dynamics (NEMD) simulations of steady-state systems with periodic\nboundary conditions -- one based on frequent particle displacements and one\nbased on the application of external bulk forces with an inhomogeneous force\nprofile.\n  In equilibrium simulations, viscosities can be determined from the stress\ntensor fluctuations via Green-Kubo relations; however, the correct\nincorporation of random and dissipative forces is not obvious. We discuss\ndifferent expressions proposed in the literature and test them at the example\nof a dissipative particle dynamics (DPD) fluid."
    },
    {
        "anchor": "Aharonov-Bohm-like effect for light propagating in nematics with\n  disclinations: Using a geometric approach for the propagation of light in anisotropic media,\nwe investigate what effect the director field of disclinations may have on the\npolarization state of light. Parallel transport around the defect, of the\nspinor describing the polarization, indicates the acquisition of a topological\nphase, in analogy with the Aharonov-Bohm effect.",
        "positive": "Why liquids are fragile: The fragilities (Tg-normalized temperature dependence of alpha-relaxation\ntimes) of 33 glass-forming liquids and polymers are compared for isobaric, mP,\nand isochoric, mV, conditions. We find that the two quantities are linearly\ncorrelated, mP = (37 +/- 3) + (0.84 +/- 0.5)mV. This result has obvious\nimportant consequences, since the ratio mV/mP is a measure of the relative\ndegree to which temperature and density control the dynamics, Moreover, we show\nthat the fragility itself is a consequence of the relative interplay of\ntemperature and density effects near Tg. Specifically, strong behavior reflects\na substantial contribution from density (jammed dynamics), while the relaxation\nof fragile liquids is more thermally-activated. Drawing on a scaling law, a\nphysical interpretation of this result in terms of the intermolecular potential\nis offered."
    },
    {
        "anchor": "Connectivity of the Hexagonal, Cubic, and Isotropic Phases of the\n  C$_{12}$EO$_6$/H$_2$O Lyotropic Mixture Investigated by Tracer Diffusion and\n  X-ray Scattering: The connectivity of the hydrophobic medium in the nonionic binary system\nC$_{12}$EO$_6$/H$_2$O is studied by monitoring the diffusion constants of\ntracer molecules at the transition between the hexagonal mesophase and the\nfluid isotropic phase. The increase in the transverse diffusion coefficient on\napproaching the isotropic phase reveals the proliferation of bridgelike defects\nconnecting the surfactant cylinders. This suggests that the isotropic phase has\na highly connected structure. Indeed, we find similar diffusion coefficients in\nthe isotropic and cubic bicontinuous phases. The temperature dependence of the\nlattice parameter in the hexagonal phase confirms the change in connectivity\nclose to the hexagonal-isotropic transition. Finally, an X-ray investigation of\nthe isotropic phase shows that its structure is locally similar to that of the\nhexagonal phase.",
        "positive": "Density and concentration field description of nonperiodic structures: We propose a simple nonlocal energy functional that is suitable for the\ncontinuum field characterization of nonperiodic and localized textures. The\nphenomenological functional is based on the pairwise direction-dependent\ninteraction of field gradients that are separated by a fixed distance. In an\nappendix, we describe the numerical minimization of our functional. On that\nbasis, we investigate the kinetic evolution of thread-like stripe patterns that\nare created by the functional when we start from an initially disordered state.\nAt later stages, we find a coarse-graining that shows the same scaling behavior\nas was obtained for the Cahn-Hilliard equation. In fact, the Cahn-Hilliard\nmodel is contained in our characterization as a limiting case. A slight\nmodification of our model omits this coarse-graining and leads to nonperiodic\nstripe phases. For the latter case, we investigate the temporal evolution of\nthe defects (end points) of the thread-like stripes. In view of possible\napplications of this functional, we discuss a possible characterization of\npolymeric systems and vesicles. The statistics of the growth of the thread-like\nstructures is compared to the case of step-growth polymerization reactions.\nFurthermore, we demonstrate that the functional may be applied for the study of\nvesicles in a continuum field description. Basic features, such as the tendency\nof tank-treading in simple shear flows and parachute folding in pipe flows, are\nreproduced."
    },
    {
        "anchor": "Shape Dynamics of Interfacial Front in Rotating Cylinders: The evolution of the interface propagation in a slowly rotating half-filled\nhorizontal cylinder is studied using MRI. Initially, the cylinder contains two\naxially segregated bands of small and large particles with a sharp interface.\nThe process of the formation of the radial core is clearly captured, and the\nshape and the velocity of the propagating front are calculated by assuming a\none-dimensional diffusion process along the rotation axis of the cylinder and a\nseparation of time scales associated with segregation in the radial and axial\ndirections. We found that the interfacial dynamics are best described when a\nconcentration dependent diffusion process is assumed.",
        "positive": "Reverse undercompressive shock structures in driven thin film flow: We show experimental evidence of a new structure involving an\nundercompressive and reverse undercompressive shock for draining films driven\nby a surface tension gradient against gravity. The reverse undercompressive\nshock is unstable to transverse perturbations while the leading\nundercompressive shock is stable. Depending on the pinch-off film thickness, as\ncontrolled by the meniscus, either a trailing rarefaction wave or a compressive\nshock separates from the reverse undercompressive shock."
    },
    {
        "anchor": "Molecular Weight Dependence of Polymersome Membrane Elasticity and\n  Stability: Vesicles prepared in water from a series of diblock copolymers and termed\n\"polymersomes\" are physically characterized. With increasing molecular weight\n$\\bar{M}_n$, the hydrophobic core thickness $d$ for the self-assembled bilayers\nof polyethyleneoxide - polybutadiene (PEO-PBD) increases up to 20 $nm$ -\nconsiderably greater than any previously studied lipid system. The mechanical\nresponses of these membranes, specifically, the area elastic modulus $K_a$ and\nmaximal areal strain $\\alpha_c$ are measured by micromanipulation. As expected\nfor interface-dominated elasticity, $K_a$ ($\\simeq$ 100 $pN/nm$) is found to be\nindependent of $\\bar{M}_n$. Related mean-field ideas also predict a limiting\nvalue for $\\alpha_c$ which is universal and about 10-fold above that typical of\nlipids. Experiments indeed show $\\alpha_c$ generally increases with\n$\\bar{M}_n$, coming close to the theoretical limit before stress relaxation is\nopposed by what might be chain entanglements at the highest $\\bar{M}_n$. The\nresults highlight the interfacial limits of self-assemblies at the nano-scale.",
        "positive": "Role of the potential landscape on the single-file diffusion through\n  channels: Transport of colloid particles through narrow channels is ubiquitous in cell\nbiology as well as becoming increasingly important for microfluidic\napplications or targeted drug delivery. Membrane channels in cells are useful\nmodels for artificial designs because of their high efficiency, selectivity and\nrobustness to external fluctuations. Here we model the passive channels that\nlet cargo simply diffuse through them, affected by a potential profile along\nthe way. Passive transporters achieve high levels of efficiency and specificity\nfrom binding interactions with the cargo inside the channel. This however leads\nto a paradox: why should channels which are so narrow that they are blocked by\ntheir cargo evolve to have binding regions for their cargo if that will\neffectively block them? Using Brownian dynamics simulations, we show that\ndifferent potentials, notably symmetric, increase the flux through narrow\npassive channels -- and investigate how shape and depth of potentials influence\nthe flux. We find that there exist optimal depths for certain potential shapes\nand that it is most efficient to apply a small force over an extended region of\nthe channel. On the other hand, having several spatially discrete binding\npockets will not alter the flux significantly. We also explore the role of\nmany-particle effects arising from pairwise particle interactions with their\nneighbours and demonstrate that the relative changes in flux can be accounted\nfor by the kinetics of the absorption reaction at the end of the channel."
    },
    {
        "anchor": "Granular binary mixtures improve energy dissipation efficiency of\n  granular dampers: Granular dampers are systems used to attenuate undesired vibrations produced\nby mechanical devices. They consist of cavities filled by granular particles.\nIn this work, we consider a granular damper filled with a binary mixture of\nfrictionless spherical particles of the same material but different size using\nnumerical discrete element method simulations. We show that the damping\nefficiency is largely influenced by the composition of the binary mixture.",
        "positive": "Decoupling of rotation and translation at the colloidal glass transition: Little is known about the coupling of rotation and translation in dense\nsystems. Here, we report results of confocal fluorescence microscopy where\nsimultaneous recording of translational and rotational particle trajectories\nfrom a bidisperse colloidal dispersion is achieved by spiking the samples with\nrotational probe particles. The latter consist of colloidal particles\ncontaining two fluorescently labelled cores suited for tracking the particle's\norientation. A comparison of the experimental data with event driven Brownian\nsimulations gives insight into the system's structure and dynamics close to the\nglass transition and sheds new light onto the translation-rotation coupling.\nThe data show that with increasing volume fractions, translational dynamics\nslows down drastically, whereas rotational dynamics changes very little. We\nfind convincing agreement between simulation and experiments, even though the\nsimulations neglect far-field hydrodynamic interactions. An additional analysis\nof the glass transition following mode coupling theory works well for the\nstructural dynamics but indicates a decoupling of the diffusion of the smaller\nparticle species. The shear stress correlations do not decorrelate in the\nsimulated glass states and are not affected by rotational motion."
    },
    {
        "anchor": "Time correlation functions in the Lebwohl-Lasher model of liquid\n  crystals: Time correlation functions in the Lebwohl-Lasher model of nematic liquid\ncrystals are studied using theory and molecular dynamics simulations. In\nparticular, the autocorrelation functions of angular momentum and nematic\ndirector fluctuations are calculated in the long-wavelength limit. The\nconstitutive relations for the hydrodynamic currents are derived using a\nstandard procedure based on non-negativity of the entropy production. The\ncontinuity equations are then linearized and solved to calculate the\ncorrelation functions. We find that the transverse angular momentum\nfluctuations are coupled to the director fluctuations, and are both\npropagative. The propagative nature of the fluctuations suppress the\nanticipated hydrodynamic long-time tails in the single-particle autocorrelation\nfunctions. The fluctuations in the isotropic phase are however diffusive,\nleading to $t^{-d/2}$ long-time tails in $d$ spatial dimensions. The Frank\nelastic constant measured using the time-correlation functions are in good\nagreement with previously reported results.",
        "positive": "Diversity of phase transitions and phase separations in active fluids: Active matter is not only indispensable to our understanding of diverse\nbiological processes, but also provides a fertile ground for discovering novel\nphysics. Many emergent properties impossible for equilibrium systems have been\ndemonstrated in active systems. These emergent features include\nmotility-induced phase separation, long-ranged ordered (collective motion)\nphase in two dimensions, and order-disorder phase co-existences (banding and\nreverse-banding regimes). Here, we unify these diverse phase transitions and\nphase co-existences into a single formulation based on generic hydrodynamic\nequations for active fluids. We also reveal a novel co-moving co-existence\nphase and a putative novel critical point."
    },
    {
        "anchor": "Vortex precession in Bose-Einstein condensates: observations with filled\n  and empty cores: We have observed and characterized the dynamics of singly quantized vortices\nin dilute-gas Bose-Einstein condensates. Our condensates are produced in a\nsuperposition of two internal states of 87Rb, with one state supporting a\nvortex and the other filling the vortex core. Subsequently, the state filling\nthe core can be partially or completely removed, reducing the radius of the\ncore by as much as a factor of 13, all the way down to its bare value. The\ncorresponding superfluid rotation rates, evaluated at the core radius, vary by\na factor of 150, but the precession frequency of the vortex core about the\ncondensate axis changes by only a factor of two.",
        "positive": "Multiple Scale Reorganization of Electrostatic Complexes of PolyStyrene\n  Sulfonate and Lysozyme: We report on a SANS investigation into the potential for these structural\nreorganization of complexes composed of lysozyme and small PSS chains of\nopposite charge if the physicochemical conditions of the solutions are changed\nafter their formation. Mixtures of solutions of lysozyme and PSS with high\nmatter content and with an introduced charge ratio [-]/[+]intro close to the\nelectrostatic stoichiometry, lead to suspensions that are macroscopically\nstable. They are composed at local scale of dense globular primary complexes of\nradius ~ 100 {\\AA}; at a higher scale they are organized fractally with a\ndimension 2.1. We first show that the dilution of the solution of complexes,\nall other physicochemical parameters remaining constant, induces a macroscopic\ndestabilization of the solutions but does not modify the structure of the\ncomplexes at submicronic scales. This suggests that the colloidal stability of\nthe complexes can be explained by the interlocking of the fractal aggregates in\na network at high concentration: dilution does not break the local aggregate\nstructure but it does destroy the network. We show, secondly, that the addition\nof salt does not change the almost frozen inner structure of the cores of the\nprimary complexes, although it does encourage growth of the complexes; these\ncoalesce into larger complexes as salt has partially screened the electrostatic\nrepulsions between two primary complexes. These larger primary complexes remain\naggregated with a fractal dimension of 2.1. Thirdly, we show that the addition\nof PSS chains up to [-]/[+]intro ~ 20, after the formation of the primary\ncomplex with a [-]/[+]intro close to 1, only slightly changes the inner\nstructure of the primary complexes. Moreover, in contrast to the synthesis\nachieved in the one-step mixing procedure where the proteins are unfolded for a\nrange of [-]/[+]intro, the native conformation of the proteins is preserved\ninside the frozen core."
    },
    {
        "anchor": "Acoustic crystallization and heterogeneous nucleation: By focusing a high intensity acoustic wave in liquid helium, we have observed\nthe nucleation of solid helium inside the wave above a certain threshold in\namplitude. The nucleation is a stochastic phenomenon. Its probability increases\ncontinuously from 0 to 1 in a narrow pressure interval around Pm + 4.7 bars (Pm\nis the melting pressure where liquid and solid helium are in equilibrium). This\noverpressure is larger by two to three orders of magnitude than what had been\npreviously observed. Our result strongly supports a recent suggestion by\nBalibar, Mizusaki and Sasaki that, in all previous experiments, solid helium\nnucleated on impurities.",
        "positive": "Phase diagram for a single flexible Stockmayer polymer at zero field: The equilibrium conformations of a flexible permanent magnetic chain that\nconsists of a sequence of linked magnetic colloidal nanoparticles with\nshort-ranged Lennard-Jones attractive interactions (Stockmayer polymer) are\nthoroughly analysed via Langevin dynamics simulations. A tentative phase\ndiagram is presented for a chain of length $N=100$. The phase diagram exhibits\nseveral unusual conformational phases when compared with the non-magnetic\nchains. These phases are characterised by a large degree of conformational\nanisotropy, and consist of closed chains, helicoidal-like states, partially\ncollapsed states, and very compact disordered states. The phase diagram\ncontains several interesting features like the existence of at least two\n'triple points'."
    },
    {
        "anchor": "Control of pathways and yields of protein crystallization through the\n  interplay of nonspecific and specific attractions: We use computer simulation to study crystal-forming model proteins equipped\nwith interactions that are both orientationally specific and nonspecific.\nDistinct dynamical pathways of crystal formation can be selected by tuning the\nstrengths of these interactions. When the nonspecific interaction is strong,\nliquidlike clustering can precede crystallization; when it is weak, growth can\nproceed via ordered nuclei. Crystal yields are in certain parameter regimes\nenhanced by the nonspecific interaction, even though it promotes association\nwithout local crystalline order. Our results suggest that equipping nanoscale\ncomponents with weak nonspecific interactions (such as depletion attractions)\ncan alter both their dynamical pathway of assembly and optimize the yield of\nthe resulting material.",
        "positive": "On the equivalence of self-consistent equations for nonuniform liquids:\n  a unified description of the various modifications: A variety of self-consistent (SC) equations have been proposed for\nnon-uniform states of liquid particles under external fields, including\nadsorbed states at solid substrates and confined states in pores. External\nfields represent not only confining geometries but also fixed solutes. We\nconsider SC equations ranging from the modified Poisson-Boltzmann equations for\nthe Coulomb potential to the hydrostatic linear response equation for the\nequilibrium density distribution of Lennard-Jones fluids. Here, we present a\nunified equation that explains the apparent diversity of previous forms and\nproves the equivalence of various SC equations. This unified description of SC\nequations is obtained from a hybrid method combining the conventional density\nfunctional theory and statistical field theory. The Gaussian approximation of\ndensity fluctuations around a mean-field distribution is performed based on the\ndeveloped hybrid framework, allowing us to derive a novel form of the\ngrand-potential density functional that provides the unified SC equation for\nequilibrium density."
    },
    {
        "anchor": "Three-Dimensional Nonlinear Lattices: From Oblique Vortices and\n  Octupoles to Discrete Diamonds and Vortex Cubes: We construct a variety of novel localized states with distinct topological\nstructures in the 3D discrete nonlinear Schr{\\\"{o}}dinger equation. The states\ncan be created in Bose-Einstein condensates trapped in strong optical lattices,\nand crystals built of microresonators. These new structures, most of which have\nno counterparts in lower dimensions, range from purely real patterns of dipole,\nquadrupole and octupole types to vortex solutions, such as \"diagonal\" and\n\"oblique\" vortices, with axes oriented along the respective directions\n$(1,1,1)$ and $(1,1,0)$. Vortex \"cubes\" (stacks of two quasi-planar vortices\nwith like or opposite polarities) and \"diamonds\" (discrete skyrmions formed by\ntwo vortices with orthogonal axes) are constructed too. We identify stability\nregions of these 3D solutions and compare them with their 2D counterparts, if\nany. An explanation for the stability/instability of most solutions is\nproposed. The evolution of unstable states is studied as well.",
        "positive": "Wormlike chain or tense string? A question of resolution: It is shown that a wormlike chain, i.e., a filament with a fixed\ncontour-length S and a bending elasticity kappa, attached to a frame of length\nL, can be described--at low resolutions--by the same type of elastic\nfree-energy as a tense string. The corresponding tension is calculated as a\nfunction of temperature, L, kappa and S."
    },
    {
        "anchor": "Defect Dynamics in Artificial Colloidal Ice: Real-Time Observation,\n  Manipulation and Logic Gate: We study the defect dynamics in a colloidal spin ice system realized by\nfilling a square lattice of topographic double well islands with repulsively\ninteracting magnetic colloids. We focus on the contraction of defects in the\nground state, and contraction/expansion in a metastable biased state. Combining\nreal-time experiments with simulations, we prove that these defects behave like\nemergent topological monopoles obeying a Coulomb law with an additional line\ntension. We further show how to realize a completely resettable \"NOR\" gate,\nwhich provides guidelines for fabrication of nanoscale logic devices based on\nthe motion of topological magnetic monopoles.",
        "positive": "Non-monotonic Size Dependence of Diffusion and Levitation Effect: A Mode\n  Coupling Theory Analysis: We present a study of diffusion of small tagged particles in a solvent, using\nmode coupling theory (MCT) analysis and computer simulations. The study is\ncarried out for various interaction potentials. For the first time, using MCT,\nit is shown that for strongly attractive interaction potential with soft core\n(allowing interpenetration between the solute-solvent pair) the diffusion\nexhibits a non-monotonic size dependence. This was earlier predicted in\nsimulation and experimental studies and was connected to levitation effect [J.\nPhys. Chem. B 2005, 109, 5824-5835]. Our MCT analysis reveals that for weak or\nno attractive interactions, all the small solute particles studied here show\nlevitation through the inter-solvent transient cage. However, for strong\nattractive interaction the levitation is not present for the smallest particle\nsizes. It is found that for systems where the interaction potential is hard,\nnot allowing any interpenetration between the solute-solvent pair, the solute\ncannot explore the inter-solvent cage. Thus these systems will never show any\nnon monotonic size dependence of diffusion. We also show that although\nlevitation is a dynamic phenomena, the effect of levitation can be obtained in\nthe radial distribution function."
    },
    {
        "anchor": "A Small-gap Effective-Temperature Model of Transient Shear Band\n  Formation During Flow: Recent Couette-cell shear experiments of carbopol gels have revealed the\nformation of a transient shear band before reaching the steady state, which is\ncharacterized by homogeneous flow. This shear band is observed in the small-gap\nlimit where the shear stress is spatially uniform. An effective-temperature\nmodel of the transient shear banding and solid-fluid transition is developed\nfor the small-gap limit. The small-gap model demonstrates the ability of a\ncontinuum-constitutive law that is based solely on microstructural\nrearrangements of the gel to account for this transient behavior, and\nidentifies that it proceeds via two distinct processes. A shear band nucleates\nand gradually broadens via disordering at the interface of the band.\nSimultaneously, spatially homogeneous fluidization is induced outside of the\nshear band where the disorder of the gel grows uniformly. Experimental data are\nused to determine the physical parameters of the theory, and direct,\nquantitative comparison is made to measurements of the structural evolution of\nthe gel, its fluidization time, and its mechanical response under plastic flow.",
        "positive": "Shape transitions in a soft incompressible sphere with residual stresses: Residual stresses may appear in elastic bodies due to the formation of\nmisfits in the micro-structure, driven by plastic deformations, thermal or\ngrowth processes. They are especially widespread in living matter, resulting\nfrom the dynamic remodelling processes aiming at optimizing the overall\nstructural response to environmental physical forces. From a mechanical\nviewpoint, residual stresses are classically modelled through the introduction\nof a virtual incompatible state that collects the local relaxed states around\neach material point. In this work, we instead employ an alternative approach\nbased on a strain energy function that constitutively depends only on the\ndeformation gradient and the residual stress tensor. In particular, our\nobjective is to study the morphological stability of an incompressible sphere,\nmade of a neo-Hookean material and subjected to given distributions of residual\nstresses. Firstly, we perform a linear stability analysis on the pre-stressed\nsolid sphere using the method of incremental deformations. The marginal\nstability conditions are given as a function of a control parameter, being the\ndimensionless variable that represents the characteristic intensity of the\nresidual stresses. Secondly, we perform finite element simulations using a\nmixed formulation in order to investigate the post-buckling morphology in the\nfully nonlinear regime. Considering different distributions of the residual\nstresses, we find that different morphological transitions occur around the\nmaterial domain where the hoop residual stress reaches its maximum compressive\nvalue. The results provide useful guidelines in order to design morphable soft\nspheres, for example by controlling the residual stresses through active\ndeformations. They finally suggest a viable solution for the nondestructive\ncharacterization of residual stresses in soft tissues, such as solid tumors."
    },
    {
        "anchor": "Shear Mediated Elongational Flow and Yielding in Soft Glassy Materials: In this work, we study the deformation behavior of thin films of various soft\nglassy materials that are simultaneously subjected to two creep flow fields,\nrotational shear flow by applying torque and elongational flow by applying\nnormal force. The generic behavior under the combined fields is investigated in\ndifferent soft glassy materials with diverse microstructure such as: hair gel,\nemulsion paint, shaving foam and clay suspension. Increase in strength of one\nstress component while keeping the other constant, not only leads to an\nexpected enhanced deformation in its own direction, but also greater strain in\nthe other direction. Herschel Bulkley model is observed to explain this\nbehavior qualitatively. Elongational flow induced in the materials eventually\ncauses failure in the same. Interestingly time to failure is observed to be\nstrongly dependent not just on normal force but also on the applied rotational\nshear stress. We believe that the presence of a three dimensional jammed\nstructure, in which overall unjamming can be induced by applying stress having\nsufficient magnitude irrespective of the direction leads to the observed\nbehavior. In addition, we observe self-similarity in the elongational as well\nas rotational strain time curves corresponding to various combinations of both\nthe fields. This observation suggests a mere shift in the time-scales involved\nkeeping the path followed in the process unchanged. A phase diagram is also\nconstructed for various soft glassy materials by determining different\ncombinations of orthogonal stresses beyond which materials yield. Estimated\nyield stress in the limit of flow dominated by applied tensile force on the top\nplate demonstrates scatter, which might be originating from fingering\ninstability. Except this deviation, yielding is observed when the invariant of\nstress tensor exceeds yield stress, validating the Von Mises criterion.",
        "positive": "Numerical calculation of free-energy barriers for entangled polymer\n  nucleation: The crystallisation of entangled polymers from their melt is investigated\nusing computer simulation with a coarse-grained model. Using hybrid Monte Carlo\nsimulations enables us to probe the behaviour of long polymer chains. We\nidentify solid-like beads with a centrosymmetry local order parameter and\ncompute the nucleation free-energy barrier at relatively high supercooling with\nadaptive-bias windowed umbrella sampling. Our results demonstrate that the\ncritical nucleus sizes and the heights of free-energy barriers do not\nsignificantly depend on the molecular weight of the polymer; however, the\nnucleation rate decreases with increasing molecular weight. Moreover, an\nanalysis of the composition of the critical nucleus suggests that\nintramolecular growth of the nucleated cluster does not contribute\nsignificantly to crystallisation for this system."
    },
    {
        "anchor": "Enslaved Phase-Separation Fronts in One-Dimensional Binary Mixtures: Phase-separation fronts leave in their wakes morphologies that are\nsubstantially different from the morphologies formed in homogeneous\nphase-separation. In this paper we focus on fronts in binary mixtures that are\nenslaved phase-separation fronts, i.e. fronts that follow in the wake of a\ncontrol-parameter front. In the one-dimensional case, which is the focus of\nthis paper, the formed morphology is deceptively simple: alternating domains of\na regular size. However, determining the size of these domains as a function of\nthe front speed and other system parameters is a non-trivial problem. We\npresent an analytical solution for the case where no material is deposited\nahead of the front and numerical solutions and scaling arguments for more\ngeneral cases. Through these enslaved phase-separation fronts large domains can\nbe formed that are practically unattainable in homogeneous one-dimensional\nphase-separation.",
        "positive": "Effect of chain stiffness on ion distributions around a polyelectrolyte\n  in multivalent salt solutions: Ion distributions in dilute polyelectrolyte solutions are studied by means of\nLangevin dynamics simulations. We show that the distributions depend on the\nconformation of a chain while the conformation is determined by the chain\nstiffness and the salt concentration. We observe that the monovalent\ncounterions originally condensed on a chain can be replaced by the multivalent\nones dissociated from the added salt due to strong electrostatic interaction.\nThese newly condensed ions give an important impact on the chain structure. At\nlow and at high salt concentrations, the conformation of a semiflexible chain\nis rodlike. The ion distributions show similarity to those for a rigid chain,\nbut difference to those for a flexible chain whose conformation is a coil. In\nthe mid-salt region, the flexible chain and the semiflexible chain collapse but\nthe collapsed chain structures are, respectively, disordered and ordered\nstructures. The ion distributions hence show different profiles for these three\nchain stiffness with the curves for the semiflexible chain lying between those\nfor the flexible and the rigid chains. The number of the condensed multivalent\ncounterions, as well as the effective chain charge, also shows similar\nbehavior, demonstrating a direct connection with the chain morphology.\nMoreover, we find that the condensed multivalent counterions form triplets with\ntwo adjacent monomers and are localized on the chain axis at intermediate salt\nconcentration when the chain stiffness is semiflexible or rigid. The\nmicroscopic information obtained here provides valuable insight to the\nphenomena of DNA condensation and is very useful for researchers to develop new\nmodels."
    },
    {
        "anchor": "Euler-Lagrangian dynamics to the physical interpretation with granular\n  constraints for MD simulations: In this article, Euler-Lagrangian dynamics explain that the two particle\ninteraction has non-conservative forces about the frame of the center of mass.\nThis interpretation clarifies the underlying interaction and the system\ndescriptions become advantages for MD simulations.",
        "positive": "Formation of Diblock Copolymer Nanoparticles: Theoretical Aspects: We explore the shape and internal structure of diblock copolymer (di-BCP)\nnanoparticles (NPs) by using the Ginzburg-Landau free-energy expansion. The\nself-assembly of di-BCP lamellae confined in emulsion droplets can form either\nellipsoidal or onion-like NPs. The corresponding inner structure is a lamellar\nphase that is either perpendicular to the long axis of the ellipsoids\n(L$_\\perp$) or forms a multi-layer concentric shell (C$_\\parallel$),\nrespectively. We focus on the effects of the interaction parameter between the\nA/B monomers $\\tau$, and the polymer/solvent $\\chi$, as well as the NP size on\nthe nanoparticle shape and internal morphology. The aspect ratio ($l_{\\rm AR}$)\ndefined as the length ratio between the long and short axes is used to\ncharacterize the overall NP shape. Our results show that for the solvent that\nis neutral towards the two blocks, as $\\tau$ increases, the $l_{\\rm AR}$ of the\nNP first increases and then decreases, indicating that the NP becomes more\nelongated and then changes to a spherical NP. Likewise, decreasing $\\chi$ or\nincreasing the NP size can result in a more elongated NP. However, when the\nsolvent has a preference towards the A or B blocks, the NP shape changes from\nstriped ellipsoid to onion-like sphere by increasing the A/B preference\nparameter strength. The critical condition of the transition from an L$_\\perp$\nto C$_\\parallel$ phase has been identified. Our results are in good agreement\nwith previous experiments, and some of our predictions could be tested in\nfuture experiments."
    },
    {
        "anchor": "Supercooled water confined in a metal-organic framework: Within the so-called \"no-man's land\" between about 150 and 235 K,\ncrystallization of bulk water is inevitable. The glasslike freezing and a\nliquid-to-liquid transition of water, predicted to occur in this region, can be\ninvestigated by confining water in nanometer-sized pores. Here we report the\nmolecular dynamics of water within the pores of a metal-organic framework using\ndielectric spectroscopy. The detected temperature-dependent dynamics of\nsupercooled water matches that of bulk water as reported outside the borders of\nthe no-man's land. In confinement, a different type of water is formed,\nnevertheless still undergoing a glass transition with considerable molecular\ncooperativity. Two different length scales seem to exist in water: A smaller\none, of the order of 2 nm, being the cooperativity length scale governing\nglassy freezing, and a larger one (> 2 nm), characterizing the minimum size of\nthe hydrogen-bonded network needed to create \"real\" water with its unique\ndynamic properties",
        "positive": "Transition from confined to bulk dynamics in symmetric star-linear\n  polymer mixtures: We report on the linear viscoelastic properties of mixtures comprising\nmultiarm star (as model soft colloids) and long linear chain homopolymers in a\ngood solvent. In contrast to earlier works, we investigated symmetric mixtures\n(with a size ratio of 1) and showed that the polymeric and colloidal responses\ncan be decoupled. The adopted experimental protocol involved probing the linear\nchain dynamics in different star environments. To this end, we studied mixtures\nwith different star mass fraction, which was kept constant while linear chains\nwere added and their entanglement plateau modulus ($G_p$) and terminal\nrelaxation time ($\\tau_d$) were measured as functions of their concentration.\nTwo distinct scaling regimes were observed for both $G_p$ and $\\tau_d$: at low\nlinear polymer concentrations, a weak concentration dependence was observed,\nthat became even weaker as the fraction of stars in the mixtures increased into\nthe star glassy regime. On the other hand, at higher linear polymer\nconcentrations, the classical entangled polymer scaling was recovered. Simple\nscaling arguments show that the threshold crossover concentration between the\ntwo regimes corresponds to the maximum osmotic star compression and signals the\ntransition from confined to bulk dynamics. These results provide the needed\ningredients to complete the state diagram of soft colloid-polymer mixtures and\ninvestigate their dynamics at large polymer-colloid size ratios. They also\noffer an alternative way to explore aspects of the colloidal glass transition\nand the polymer dynamics in confinement. Finally, they provide a new avenue to\ntailor the rheology of soft composites."
    },
    {
        "anchor": "Self-Assembly of Core-Shell Hybrid Nanoparticles by Directional\n  Crystallization of Grafted Polymers: Nanoparticle self-assembly is an efficient bottom-up strategy for the\ncreation of nanostructures. In the standard approach, ligands are grafted on\nthe surfaces of nanoparticles to keep them separated and control interparticle\ninteractions. Ligands then remain secondary and usually are not expected to\norder significantly during superstructure formation. Here, we investigate how\nligands can play a more primary role in the formation of inorganic-organic\nhybrid materials. We graft poly(2-iso-propyl-2-oxazoline) (PiPrOx) as a\ncrystallizable shell onto SiO$_2$ nanoparticles. By varying the PiPrOx grafting\ndensity, solution stability, and nanoparticle aggregation behavior can be\ncontrolled. Upon prolonged heating, anisotropic nanostructures form in\nconjunction with the crystallization of the ligands. Self-assembly of hybrid\nPiPrOx@SiO$_2$ (shell@core) nanoparticles proceeds in two steps: First, rapid\nformation of amorphous aggregates via gelation, mediated by the interaction\nbetween nanoparticles through grafted polymers; second, slow radial growth of\nfibers via directional crystallization, governed by the incorporation of\ncrystalline ribbons formed from unbound polymers coupling to the grafted\npolymer shell. Our work reveals how crystallization-driven self-assembly of\nligands can create intricate hybrid nanostructures.",
        "positive": "Connecting Inverse Design with Experimentally Relevant Models: While colloids are promising building blocks for the self-assembly of\nmaterials with novel microstructures, their numerous tunable parameters inhibit\nbrute force searching for appropriate parameter combinations that yield\nself-assembly of a desired structure. Instead, inverse approaches that invoke a\nsystematic optimization framework can effectively navigate this design space.\nIn this proceeding, we apply one such inverse technique, Relative Entropy\nMinimization, to discover isotropic pairwise interaction potentials that prompt\nself-assembly of clusters in silico. The functional form of the pair\ninteraction is chosen to model a mixture of charged colloids and neutral\npolymers that act as depletants, and the parameters are directly connected to\nexperimentally tunable quantities."
    },
    {
        "anchor": "Relaxation and Creep in Twist and Flexure + Addendum to <<Relaxation and\n  Creep in Twist and Flexure>>: The aim of the paper is to derive the exact analytical expressions for\ntorsion and bending creep of rods with the Norton-Bailey, Garofalo and\nNaumenko-Altenbach-Gorash constitutive models. These simple constitutive\nmodels, for example, the time- and strain-hardening constitutive equations,\nwere based on adaptations for time-varying stress of equally simple models for\nthe secondary creep stage from constant load/stress uniaxial tests where\nminimum creep rate is constant. The analytical solution is studied for\nNorton-Bailey and Garofalo laws in uniaxial states of stress. The most common\nsecondary creep constitutive model has been the Norton-Bailey Law which gives a\npower law relationship between minimum creep rate and (constant) stress. The\ndistinctive mathematical properties of the power law allowed the development of\nanalytical methods, many of which can be found in high temperature design\ncodes. The results of creep simulation are applied to practically important\nproblem of engineering, namely for simulation of creep and relaxation of\nhelical and disk springs. The exact analyticalexpressions giving the torque and\nbending moment as a function of the time were derived.",
        "positive": "Quasi-rigidity: some uniqueness issues: Quasi-rigidity means that one builds a theory for assemblies of grains under\na slowly changing external load by using the deformation of those grains as a\nsmall parameter. Is quasi-rigidity a complete theory for these granular\nassemblies? Does it provide unique predictions of the assembly's behavior, or\nmust some other process be invoked to decide between several possibilities? We\nprovide evidence that quasi-rigidity is a complete theory by showing that two\npossible sources of indeterminacy do not exist for the case of disk shaped\ngrains. One possible source of indeterminacy arises from zero-frequency modes\npresent in the packing. This problem can be solved by considering the\nconditions required to obtain force equilibrium. A second possible source of\nindeterminacy is the necessity to choose the status (sliding or non-sliding) at\neach contact. We show that only one choice is permitted, if contacts slide only\nwhen required by Coulomb friction."
    },
    {
        "anchor": "Manifestation of the collective drift of molecules in argon according to\n  their mean square displacements: The mean square displacement (MSD) of an argon molecule as a function of time\nis studied. Its deviations from the standard asymptotic law for intermediate\ntimes are analyzed in details. It is shown that these deviations are mainly\nconnected with the square-root contribution to the MSD which is proportional\nthe ratio of the collective part to the full self-diffusion coefficient. It is\nestablished that the relative value of the collective contribution to the\nself-diffusion coefficient of argon changes from 0.23 near the triple point up\nto 0.4 at approaching the critical point. A new method for the determination of\nthe Maxwell relaxation time is proposed. Its temperature dependence on the\ncoexistence curve and one of isochors is investigated.",
        "positive": "Robustness of stress focusing in soft lattices under topology-switching\n  deformation: Recent developments in topological mechanics have demonstrated the ability of\nMaxwell lattices to effectively focus stress along domain walls between\ndifferently polarized domains. The focusing ability can be exploited to protect\nthe lattice bulk from accidental stress concentration -- and eventually onset\nand propagation of fracture -- at structural hot spots such as defects and\ncracks. A recent study has revisited the problem for structural lattices\nfeaturing non-ideal hinges, showing that the focusing remains robust, albeit\ndiluted in strength. Realizing that the problem of domain wall localization has\nbeen traditionally framed in the context of linear elasticity, in this work we\nextend the study to the realm of soft structures undergoing nonlinear finite\ndeformation. Through experiments performed on silicone hyperelastic prototypes,\nwe assess and quantify the robustness of the phenomenon against the macroscopic\nshape changes induced by large deformation, with special attention to\ndeformation levels that alter the topology of the bulk, lifting the topological\nprotection. Furthermore, we identify a simple geometric indicator for this\ntransition."
    },
    {
        "anchor": "The Spectrum of Structure for Jammed and Unjammed Soft Disks: We investigate the short, medium, and long-range structure of soft disk\nconfigurations for a wide range of area fractions and simulation protocols by\nconverting the real-space spectrum of volume fraction fluctuations for windows\nof width $L$ to the distance $h(L)$ from the window boundary over which\nfluctuations occur. Rapidly quenched unjammed configurations exhibit\nsize-dependent super-Poissonian long-range features that, surprisingly,\napproach the totally-random limit even close to jamming. Above and just below\njamming, the spectra exhibit a plateau, $h(L)=h_e$, for $L$ larger than\nparticle size and smaller than a cutoff $L_c$ beyond which there are long-range\nfluctuations. The value of $h_e$ is independent of protocol and characterizes\nthe putative hyperuniform limit. This behavior is compared with that for\nEinstein solids, with and without hyperuniformity-destroying defects. We find\nthat key structural features of the particle configurations are more evident,\nas well as easier and more intuitive to quantify, using the real-space spectrum\nof hyperuniformity lengths rather than the spectral density.",
        "positive": "Mpemba meets Newton: Exploring the Mpemba and Kovacs effects in the\n  time-delayed cooling law: Despite extensive research, the fundamental physical mechanisms underlying\nthe Mpemba effect, a phenomenon where a substance cools faster after initially\nbeing heated, remain elusive. Although historically linked with water, the\nMpemba effect manifests across diverse systems, sparking heightened interest in\nMpemba-like phenomena. Concurrently, the Kovacs effect, a memory phenomenon\nobserved in materials like polymers, involves rapid quenching and subsequent\ntemperature changes, resulting in nonmonotonic relaxation behavior. This paper\nprobes the intricacies of the Mpemba and Kovacs effects within the framework of\nthe time-delayed Newton's law of cooling, recognized as a simplistic yet\neffective phenomenological model accommodating memory phenomena. This law\nallows for a nuanced comprehension of temperature variations, introducing a\ntime delay ($\\tau$) and incorporating specific protocols for the thermal bath\ntemperature, contingent on a defined waiting time ($t_{\\text{w}}$). Remarkably,\nthe relevant parameter space is two-dimensional ($\\tau$ and $t_{\\text{w}}$),\nwith bath temperatures exerting no influence on the presence or absence of the\nMpemba effect or the relative strength of the Kovacs effect. The findings\nenhance our understanding of these memory phenomena, providing valuable\ninsights applicable to researchers across diverse fields, ranging from physics\nto materials science."
    },
    {
        "anchor": "Viscous fingering in volatile thin films: A thin water film on a cleaved mica substrate undergoes a first order phase\ntransition between two values of film thickness. By inducing a finite\nevaporation rate of the water, the interface between the two phases develops a\nfingering instability similar to that observed in the Saffman-Taylor problem.\nWe draw the connection between the two problems, and construct solutions\ndescribing the dynamics of evaporation in this system.",
        "positive": "The counterion condensation of differently flexible polyelectrolyte\n  aqueous solutions in the dilute and semidilute regime: The low-frequency limit of the electrical conductivity (d.c. conductivity) of\ndifferently flexible polyions in aqueous solutions has been measured over an\nextended polyion concentration range, covering both the dilute and semidilute\n(entangled and unentangled) regime, up to the concentrated regime. The data\nhave been analyzed taking into account the different flexibility of the polymer\nchains according to the scaling theory of polyion solutions, in the case of\nflexible polyions, and according to the Manning model, in the case of rigid\npolyions. In both cases, the fraction f of free counterions, released into the\naqueous phase from the ionizable polyion groups, has been evaluated and its\ndependence on the polyion concentration determined. Our results show that the\ncounterion condensation follows at least three different regimes in dependence\non the polyion concentration. The fraction f of free counterions remains\nconstant only in the semidilute regime (a region that we have named the Manning\nregime), while there is a marked dependence on the polyion concentration both\nin the dilute and in the concentrated regime. These results are briefly\ndiscussed at the light of the aqueous ionic solutions."
    },
    {
        "anchor": "Selective Trapping of DNA using Glass Microcapillaries: We show experimentally that a cheap glass microcapillary can accumulate\n{\\lambda}-phage DNA at its tip and deliver the DNA into the capillary using a\ncombination of electro-osmotic flow, pressure-driven flow, and electrophoresis.\nWe develop an efficient simulation model for this phenomenon based on the\nelectrokinetic equations and the finite-element method. Using our model, we\nexplore the large parameter space of the trapping mechanism by varying the salt\nconcentration, the capillary surface charge, the applied voltage, the pressure\ndifference, and the mobility of the analyte molecules. Our simulation results\nshow that this system can be tuned to capture a wide range of analyte\nmolecules, such as DNA or proteins, based on their electrophoretic mobility.\nOur method for separation and pre-concentration of analytes has implications\nfor the development of low-cost lab-on-a-chip devices.",
        "positive": "Structural and elastic properties of a confined 2D colloidal solid: a\n  molecular dynamics study: We implement molecular dynamics simulations in canonical ensemble to study\nthe effect of confinement on a $2d$ crystal of point particles interacting with\nan inverse power law potential proportional to $r^{-12}$ in a narrow channel.\nThis system can describe colloidal particles at the air-water interface. It is\nshown that the system characteristics depend sensitively on the boundary\nconditions at the two {\\it walls} providing the confinement. The walls exert\nperpendicular forces on their adjacent particles. The potential between walls\nand particles varies as the inverse power of ten. Structural quantities such as\ndensity profile, structure factor and orientational order parameter are\ncomputed. It is shown that orientational order persists near the walls even at\ntemperatures where the system in the bulk is in fluid state. The dependence of\nelastic constants, stress tensor elements, shear and bulk modulii on density as\nwell as the channel width is discussed. Moreover, the effect of channel\nincommensurability with the triangular lattice structure is discussed. It is\nshown that incommensurability notably affects the system properties. We compare\nour findings to those obtained by Monte Carlo simulations and also to the case\nwith the periodic boundary condition along the channel width. ."
    },
    {
        "anchor": "Role of ionic surfactant in magnetic dynamics of self-assembled\n  dispersions of nanoplatelets: In complex colloidal systems, interparticle interactions strongly affect the\ndynamics of the constituting particles. A study of the dynamical response also\nprovides invaluable information on the character of those interactions. Here we\ndemonstrate how tuning the electrostatic interactions by an ionic surfactant in\ndispersions of magnetic nanoplatelets leads to developing new dynamic modes in\nmagnetic response spectra. The collective modes can be induced or suppressed by\neither varying the concentration ratio of the magnetic nanoplatelets (MP) to\nthe surfactant or increasing the MP concentration reflecting the nanoscale\ncharacteristics of this fluid magnet.",
        "positive": "Competition between hydrogen bonding and electric field in single-file\n  transport of water in carbon nanotubes: Recent studies have shown the possibility of water transport across carbon\nnanotubes, even in the case of nanotubes with small diameter (0.822 nm). In\nthis case, water shows subcontinuum transport following an ordered 1D structure\nstabilized by hydrogen bonds. In this work, we report MD simulations describing\nthe effect of a perpendicular electric field in this single-file water\ntransport in carbon nanotubes. We show that water permeation is substantially\nreduced for field intensities of 2-3 V/nm and it is no longer possible under\nperpendicular fields of 4 V/nm."
    },
    {
        "anchor": "Landau theory of bending-to-stretching transition: Transition from bending-dominated to stretching-dominated elastic response in\nsemi-flexible fibrous networks plays an important role in the mechanical\nbehavior of cells and tissues. It is induced by changes in network connectivity\nand relies on construction of new cross-links. We propose a simple continuum\nmodel of this transition with macroscopic strain playing the role of order\nparameter. An unusual feature of this Landau-type theory is that it is based on\na single-well potential. We predict that bending-to-stretching transition\nproceeds through propagation of the localized fronts separating domains with\naffine and non-affine elastic response.",
        "positive": "Kinetics of Ion Transport in Ionic Liquids: Two Dynamical Diffusion\n  States: Using classical molecular dynamics simulations, we investigate the mobility\nof ions in [Bmim][TFSI], a typical room temperature ionic liquid. Analyzing the\ntrajectories of individual cations and anions, we estimate the time that ions\nspend in bound, clustered states, and when the ions move quasi-freely. Using\nthis information, we evaluate the average portion of free ions that dominate\nconductivity. The amount of thus defined free ions comprises 15-25%,\nmonotonically increasing with temperature in the range of 300-600 K, with the\nrest of the ions being temporarily bound, moving rather in local potentials.\nThe conductivities as a function of temperature, calculated from electric\ncurrent autocorrelation functions, reproduce reported experimental data well.\nInterestingly, for free ions the Nernst-Einstein relationship between the\nmobility and diffusion coefficient holds fairly well. In analogy with\nelectronic semiconductors, one can speak about an ionic semiconductor model for\nionic liquids with valence (or excitonic) and conduction band states for ions,\nseparated by an energy gap. The obtained band gap for the ionic liquid is,\nhowever, very small, about 0.026 eV, allowing for easy interchanges between the\ntwo dynamic states."
    },
    {
        "anchor": "Slow relaxations and stringlike jump motions in fragile glass-forming\n  liquids: Breakdown of the Stokes-Einstein relation: We perform molecular dynamics simulation on a glass-forming liquid binary\nmixture with the soft-core potential in three dimensions. We investigate\ncrossover of the configuration changes caused by stringlike jump motions. With\nlowering the temperature $T$, the motions of the particles composing strings\nbecome larger in sizes and displacements, while those of the particles\nsurrounding strings become smaller. Then, the contribution of the latter to\ntime-correlation functions tends to be long-lived as $T$ is lowered. As a\nresult, the relaxation time $\\tau_\\alpha$ and the viscosity $\\eta$ grow more\nsteeply than the inverse diffusion constant $D^{-1}$ at low $T$, leading to\nbreakdown of the Stokes-Einstein relation. At low $T$, the diffusion occurs as\nactivation processes and may well be described by short-time analysis of rare\njump motions with broken bonds and large displacements. Some characteristic\nfeatures of the van Hove self-correlation function arise from escape jumps over\nhigh potential barriers.",
        "positive": "Manipulation of Colloids by Nonequilibrium Depletion Force in\n  Temperature Gradient: The non-equilibrium distribution of colloids in a polymer solution under a\ntemperature gradient is studied experimentally. A slight increase of local\ntemperature by a focused laser drives the colloids towards the hot region,\nresulting in the trapping of the colloids irrespective of their own\nthermophoretic properties. An amplification of the trapped colloid density with\nthe polymer concentration is measured, and is quantitatively explained by\nhydrodynamic theory. The origin of the attraction is a migration of colloids\ndriven by a non-uniform polymer distribution sustained by the polymer's\nthermophoresis. These results show how to control thermophoretic properties of\ncolloids."
    },
    {
        "anchor": "Simulations of strongly phase-separated liquid-gas systems: Lattice Boltzmann simulations of liquid-gas systems are believed to be\nrestricted to modest density ratios of less than 10. In this article we show\nthat reducing the speed of sound and, just as importantly, the interfacial\ncontributions to the pressure allows lattice Boltzmann simulations to achieve\nhigh density ratios of 1000 or more. We also present explicit expressions for\nthe limits of the parameter region in which the method gives accurate results.\nThere are two separate limiting phenomena. The first is the stability of the\nbulk liquid phase. This consideration is specific to lattice Boltzmann methods.\nThe second is a general argument for the interface discretization that applies\nto any diffuse interface method.",
        "positive": "Bubble and droplet motion in binary mixtures: Evaporation-condensation\n  mechanism and Marangoni effect: Bubble and droplet motion in binary mixtures is studied in weak heat and\ndiffusion fluxes and in gravity by solving the linearized hydrodynamic\nequations supplemented with appropriate surface boundary conditions. Without\ngravity, the velocity field is induced by evaporation and condensation at the\ninterface and by the Marangoni effect due to a surface tension gradient. In\npure fluids, the latter nearly vanishes since the interface temperature tends\nto the coexistence temperature $T_{\\rm cx}(p)$ even in heat flow. In binary\nmixtures, the velocity field can be much enhanced by the Marangoni effect above\na crossover concentration $c^*$ inversely proportional to the radius $R$ of the\nbubble or droplet. Here $c^*$ is usually very small for large $R$ for\nnon-azeotropic mixtures. The temperature and concentration deviations are also\ncalculated."
    },
    {
        "anchor": "Non-Maxwellian viscoelastic stress relaxations in soft matter: Viscoelastic stress relaxation is a basic characteristic of soft matter\nsystems such as colloids, gels, and biological networks. Although the Maxwell\nmodel of linear viscoelasticity provides a classical description of stress\nrelaxation, the Maxwell model is often not sufficient for capturing the complex\nrelaxation dynamics of soft matter. In this Tutorial, we introduce and dis-cuss\nthe physics of non-Maxwellian linear stress relaxation as observed in soft\nmaterials, the ascribed origins of this effect in different systems, and\nappropriate models that can be used to capture this relaxation behavior. We\nprovide a basic toolkit that can assist the understanding and modeling of the\nmechanical relaxation of soft materials for diverse applications.",
        "positive": "Microscopic theory for hyperuniformity in two-dimensional chiral active\n  fluid: Some nonequilibrium systems exhibit anomalous suppression of the large-scale\ndensity fluctuations, so-called hyperuniformity. Recently, hyperuniformity was\nfound numerically in a simple model of chiral active fluids [Q.-L. Lei et al.,\nSci. Adv. 5, eaau7423 (2019)]. We revisit this phenomenon and put forward a\nmicroscopic theory to explain it. An effective fluctuating hydrodynamic\nequation is derived for a simple particle model of chiral active matter. We\nshow that the linear analysis of the obtained hydrodynamic equation captures\nhyperuniformity. Our theory yields hyperuniformity characterized by the same\nexponents as the numerical observation, but the agreement with the numerical\ndata is qualitative. We also argue that the hydrodynamic equation for the\neffective particle representation, in which each rotating trajectory is\nregarded as an effective particle, has the same form as the macroscopic\ndescription of the random organization model with the center of mass\nconservation."
    },
    {
        "anchor": "Frictional rigidity percolation and minimal rigidity proliferation: From\n  a new universality class to superuniversality: We introduce two new concepts, frictional rigidity percolation and minimal\nrigidity proliferation, to help identify the nature of the frictional jamming\ntransition as well as significantly broaden the scope of rigidity percolation.\nFor frictional rigidity percolation, we construct rigid clusters in two\ndifferent lattice models using a $(3,3)$ pebble game, while taking into account\ncontacts below and at the Coulomb threshold. The first lattice is a honeycomb\nlattice with next-nearest neighbors, the second, a hierarchical lattice. For\nboth, we generally find a continuous rigidity transition. Our numerical results\nsuggest that, for the honeycomb lattice, the exponents associated with the\ntransition found with the frictional $(3,3)$ pebble game are distinct from\nthose of a central-force $(2,3)$ pebble game. We propose that localized motifs,\nsuch as hinges, connecting rigid clusters that are allowed only with friction\ncould give rise to this new frictional universality class. However, the\ncloseness of the order parameter exponent between the two cases hints at\npotential superuniversality. To explore this possibility, we construct a\nbespoke cluster generating algorithm invoking generalized Henneberg moves,\ndubbed minimal rigidity proliferation. The minimally rigid clusters the\nalgorithm generates appear to be in the same universality class as connectivity\npercolation, suggesting superuniversality between all three types of\ntransitions. Finally, the hierarchical lattice is analytically tractable and we\nfind that the exponents depend both on the type of force and on the fraction of\ncontacts at the Coulomb threshold. These combined results allow us to compare\ntwo universality classes on the same lattice via rigid clusters for the first\ntime to highlight unifying and distinguishing concepts within the set of all\npossible rigidity transitions in disordered systems.",
        "positive": "Active binary mixtures of fast and slow hard spheres: We computationally studied the phase behavior and dynamics of binary mixtures\nof active particles, where each 'species' had distinct activities leading to\ndistinct velocities, fast and slow. We obtained phase diagrams demonstrating\nmotility-induced phase separation (MIPS) upon varying the activity and\nconcentration of each species, and extended current kinetic theory of\nactive/passive mixtures to active/active mixtures. We discovered two regimes of\nbehavior quantified through the participation of each species in the dense\nphase compared to their monodisperse counterparts. In regime I (active/passive\nand active/weakly-active), we found that the dense phase was segregated by\nparticle type into domains of fast and slow particles. Moreover, fast particles\nwere suppressed from entering the dense phase while slow particles were\nenhanced entering the dense phase, compared to monodisperse systems of all-fast\nor all-slow particles. These effects decayed asymptotically as the activity of\nthe slow species increased, approaching the activity of the fast species until\nthey were negligible (regime II). In regime II, the dense phase was\nhomogeneously mixed and each species participated in the dense phase as if it\nwere it a monodisperse system; each species behaved as if it weren't mixed at\nall. Finally, we collapsed our data defining two quantities that measure the\ntotal activity of the system. We thus found expressions that predict, a priori,\nthe percentage of each particle type that participates in the dense phase\nthrough MIPS."
    },
    {
        "anchor": "Aggregation kinetics of irreversible patches coupled with reversible\n  isotropic interaction leading to chains, bundles and globules: In the present study we are performing simulation of simple model of two\npatch colloidal particles undergoing irreversible diffusion limited cluster\naggregation using patchy Brownian cluster dynamics. In addition to the\nirreversible aggregation of patches, the spheres are coupled with isotropic\nreversible aggregation through the Kern-Frenkel potential. Due to the presence\nof anisotropic and isotropic potential we have also defined 3 different kinds\nof clusters formed due to anisotropic potential and isotropic potential only as\nwell as both the potentials together. We have investigated the effect of patch\nsize on self-assembly under different solvent qualities for various volume\nfractions. We will show that at low volume fractions during aggregation\nprocess, we end up in a chain conformation for smaller patch size while in a\nglobular conformation for bigger patch size. We also observed a chain to bundle\ntransformation depending on the attractive interaction strength between the\nchains or in other words depending on the quality of the solvent. We will also\nshow that bundling process is very similar to nucleation and growth phenomena\nobserved in colloidal system with short range attraction. We have also studied\nthe bond angle distribution for this system, where for small patches only 2\nangles are more probable indicating chain formation, while for bundling at very\nlow volume fraction a tail is developed in the distribution. While for the case\nof higher patch angle this distribution is broad compared to the case of low\npatch angles showing we have a more globular conformation. We are also\nproposing a model for the formation of bundles which are similar to amyloid\nfibers using two patch colloidal particles.",
        "positive": "Conformational dynamics and internal friction in homo-polymer globules:\n  equilibrium vs. non-equilibrium simulations: We study the conformational dynamics within homo-polymer globules by\nsolvent-implicit Brownian dynamics simulations. A strong dependence of the\ninternal chain dynamics on the Lennard-Jones cohesion strength {\\epsilon} and\nthe globule size NG is observed. We find two distinct dynamical regimes: a\nliquid- like regime (for {\\epsilon} < {\\epsilon}s) with fast internal dynamics\nand a solid-like regime (for {\\epsilon} > {\\epsilon}s) with slow internal\ndynamics. The cohesion strength {\\epsilon}s of this freezing transition depends\non NG. Equilibrium simulations, where we investigate the diffusional chain\ndynamics within the globule, are compared with non-equilibrium simulations,\nwhere we unfold the globule by pulling the chain ends with prescribed velocity\n(encompassing low enough velocities so that the linear-response, viscous regime\nis reached). From both simulation protocols we derive the internal viscosity\nwithin the globule. In the liquid-like regime the internal friction increases\ncontinuously with {\\epsilon} and scales extensive in NG. This suggests an\ninternal friction scenario where the entire chain (or an extensive fraction\nthereof) takes part in conformational reorganization of the globular structure."
    },
    {
        "anchor": "Coupling Finite Element Method with Large Scale Atomic/Molecular\n  Massively Parallel Simulator (LAMMPS) for Hierarchical Multiscale Simulations: In this work, we have developed a multiscale computational algorithm to\ncouple finite element method with an open source molecular dynamics code ---\nthe Large scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) --- to\nperform hierarchical multiscale simulations in highly scalable parallel\ncomputations. The algorithm was firstly verified by performing simulations of\nsingle crystal copper deformation, and a good agreement with the\nwell-established method was confirmed. Then, we applied the multiscale method\nto simulate mechanical responses of a polymeric material composed of\nmulti-million fine scale atoms inside the representative unit cells (r-cell)\nagainst uniaxial loading. It was observed that the method can successfully\ncapture plastic deformation in the polymer at macroscale, and reproduces the\ndouble yield points typical in polymeric materials, strain localization and\nnecking deformation after the second yield point. In addition, parallel\nscalability of the multiscale algorithm was examined up to around 100 thousand\nprocessors with 10 million particles, and an almost ideal strong scaling was\nachieved thanks to LAMMPS parallel architecture.",
        "positive": "Equipartition of rotational and translational energy in a dense granular\n  gas: Experiments quantifying the rotational and translational motion of particles\nin a dense, driven, 2D granular gas floating on an air table reveal that\nkinetic energy is divided equally between the two translational and one\nrotational degrees of freedom. This equipartition persists when the particle\nproperties, confining pressure, packing density, or spatial ordering are\nchanged. While the translational velocity distributions are the same for both\nlarge and small particles, the angular velocity distributions scale with the\nparticle radius. The probability distributions of all particle velocities have\napproximately exponential tails. Additionally, we find that the system can be\ndescribed with a granular Boyle's Law with a van der Waals-like equation of\nstate. These results demonstrate ways in which conventional statistical\nmechanics can unexpectedly apply to non-equilibrium systems."
    },
    {
        "anchor": "Vesicles as osmotically stressed capsules: Vesicular capsules are used to carry biochemicals in biology and liposome\ntechnology. Being water-permeable with differing interior and exterior\ncompositions, they are necessarily under osmotic stress. Recent studies have\nunderlined the different thermodynamic behavior of osmotically stressed\nvesicles in comparison to vesicles subjected to a hydrostatic pressure as\nstudied earlier. Through their different behavior one gains access to the\nparameters affecting the osmotic swelling of vesicles, such as the\nmembrane-permeability coefficients of solute molecules.",
        "positive": "Measuring Colloidomer Hydrodynamics with Holographic Video Microscopy: In-line holographic video microscopy records a wealth of information about\nthe microscopic structure and dynamics of colloidal materials. Powerful\nanalytical techniques are available to retrieve that information when the\ncolloidal particles are well-separated. Large assemblies of close-packed\nparticles create holograms that are substantially more challenging to\ninterpret. We demonstrate that Rayleigh-Sommerfeld back-propagation is useful\nfor analyzing holograms of colloidomer chains, close-packed linear assemblies\nof micrometer-scale emulsion droplets. Colloidomers are fully flexible chains\nand undergo three-dimensional configurational changes under the combined\ninfluence of random thermal forces and hydrodynamic forces. We demonstrate the\nability of holographic reconstruction to track these changes as colloidomers\nsediment through water in a horizontal slit pore. Comparing holographically\nmeasured configurational trajectories with predictions of hydrodynamic models\nboth validates the analytical technique for this valuable class of\nself-organizing materials and also provides insights into the influence of\ngeometric confinement on colloidomer hydrodynamics."
    },
    {
        "anchor": "Crystallization of hard aspherical particles: We use numerical simulations to study the crystallization of monodisperse\nsystems of hard aspherical particles. We find that particle shape and\ncrystallizability can be easily related to each other when particles are\ncharacterized in terms of two simple and experimentally accessible order\nparameters: one based on the particle surface-to-volume ratio, and the other on\nthe angular distribution of the perturbations away from the ideal spherical\nshape. We present a phase diagram obtained by exploring the crystallizability\nof 487 different particle shapes across the two-order-parameter spectrum.\nFinally, we consider the physical properties of the crystalline structures\naccessible to aspherical particles, and discuss limits and relevance of our\nresults.",
        "positive": "A unifying model for chemical and colloidal gels: We investigate the slow dynamics in gelling systems by means of MonteCarlo\nsimulations on the cubic lattice of a minimal statistical mechanics model. By\nopportunely varying some model parameter we are able to describe a crossover\nfrom the chemical gelation behaviour to dynamics more typical of colloidal\nsystems. The results suggest a novel connection linking classical gelation, as\noriginally described by Flory, to more recent results on colloidal systems."
    },
    {
        "anchor": "Collective epithelial migration is mediated by the unbinding of hexatic\n  defects: Collective cell migration in epithelia relies on cell intercalation: i.e. a\nlocal remodelling of the cellular network that allows neighbouring cells to\nswap their positions. While in common with foams and other passive cellular\nfluids, intercalation in epithelia crucially depends on active processes, where\nthe local geometry of the network and the contractile forces generated therein\nconspire to produce an ``avalanche'' of remodelling events, which collectively\ngive rise to a vortical flow at the mesoscopic length scale. In this article we\nformulate a continuum theory of the mechanism driving this process, built upon\nrecent advances towards understanding the hexatic (i.e. $6-$fold ordered)\nstructure of epithelial layers. Using a combination of active hydrodynamics and\ncell-resolved numerical simulations, we demonstrate that cell intercalation\ntakes place via the unbinding of topological defects, naturally initiated by\nfluctuations and whose late-times dynamics is governed by the interplay between\npassive attractive forces and active self-propulsion. Our approach sheds light\non the structure of the cellular forces driving collective migration in\nepithelia and provides an explanation of the observed extensile activity of in\nvitro epithelial layers.",
        "positive": "Universal effects of solvent species on the stabilized structure of a\n  protein: We investigate the effects of solvent specificities on the stability of the\nnative structure (NS) of a protein on the basis of our free-energy function\n(FEF). We use CPB-bromodomain (CBP-BD) and apoplastocyanin (apoPC) as\nrepresentatives of the protein universe and water, methanol, ethanol, and\ncyclohexane as solvents. The NSs of CBP-BD and apoPC consist of 66$\\%$\n$\\alpha$-helices and of 35$\\%$ $\\beta$-sheets and 4$\\%$ $\\alpha$-helices,\nrespectively. In order to assess the structural stability of a given protein\nimmersed in each solvent, we contrast the FEF of its NS against that of a\nnumber of artificially created, misfolded decoys possessing the same amino-acid\nsequence but significantly different topology and $\\alpha$-helix and\n$\\beta$-sheet contents. We find that for both CBP-BD and apoPC, the energetic\ncomponent dominates in methanol, ethanol, and cyclohexane, with the most stable\nstructures in these solvents sharing the same characteristics described as an\nassociation of a-helices. In water, the entropic component is as strong as or\neven stronger than the energetic one, with a large gain of translational,\nconfigurational entropy of water becoming crucially important, so that the\nrelative contents of $\\alpha$-helix and $\\beta$-sheet and the content of total\nsecondary structures are carefully selected to achieve sufficiently close\npacking of side chains. Our analysis, which requires minimal computational\neffort, can be applied to any protein immersed in any solvent and provides\nrobust predictions that are quite consistent with the experimental observations\nfor proteins in different solvent environments, thus paving the way toward a\nmore detailed understanding of the folding process."
    },
    {
        "anchor": "Rotational and translational drags of a Janus particle close to a wall\n  and a lipid membrane: Hypothesis: Measuring rotational and translational Brownian motion of single\nspherical particles reveals dissipations due to the interaction between the\nparticle and the environment. Experiments: In this article, we show experiments\nwhere the in-plane translational and two rotational drag coefficients of a\nsingle spherical Brownian particle can be measured. These particle drags are\nfunctions of the particle size and the particle-wall distance, and of the\nviscous dissipations at play. We measure drag coefficients for Janus particles\nclose to a solid wall and close to a lipid bilayer membrane. Findings: For a\nparticle close to wall, we show that according to hydrodynamic models,\nparticlewall distance and particle size can be determined. For a particle\npartially wrapped by lipid membranes, in absence of strong binding\ninteractions, translational and rotational drags are significantly larger than\nthe ones of non-wrapped particles. Beside the effect of the membrane viscosity,\nwe show that dissipations in the deformed membrane cap region strongly\ncontribute to the drag coefficients.",
        "positive": "Charge regulation and ionic screening of patchy surfaces: The properties of surfaces with charge-regulated patches are studied using\nnon-linear Poisson-Boltzmann theory. Using a mode expansion to solve the\nnon-linear problem efficiently, we reveal the charging behaviour of\nDebye-length sized patches. We find that patches charge up to higher charge\ndensities if their size is relatively small and if the patches are well\nseparated. The numerical results are used to construct a basic analytical model\nwhich predicts the average surface charge density on surfaces with patchy\nchargeable groups."
    },
    {
        "anchor": "Compatible director fields in $\\mathbb{R}^3$: The geometry and interactions between the constituents of a liquid crystal,\nwhich are responsible for inducing the partial order in the fluid, may locally\nfavor an attempted phase that could not be realized in $\\mathbb{R}^3$. While\nstates that are incompatible with the geometry of $\\mathbb{R}^3$ were\nidentified more than 50 years ago, the collection of compatible states remained\npoorly understood and not well characterized. Recently, the compatibility\nconditions for three-dimensional director fields were derived using the method\nof moving frames. These compatibility conditions take the form of six\ndifferential relations in five scalar fields locally characterizing the\ndirector field. In this work, we rederive these equations using a more\ntransparent approach employing vector calculus. We then use these equations to\ncharacterize a wide collection of compatible phases.",
        "positive": "Non-equilibrium condensation and coarsening of field-driven dipolar\n  colloids: In colloidal suspensions, self-organization processes can be easily fueled by\nexternal fields. One particularly interesting class of phenomena occurs in\nmonolayers of dipolar particles that are driven by rotating external fields.\nHere we report results from a computer simulation study of such systems\nfocusing on the clustering behavior also observed in recent experiments. The\nkey result of this paper is a novel interpretation of this pattern formation\nphenomenon: We show the clustering to be a by-product of a vapor-liquid first\norder phase transition. In fact, the observed dynamic coarsening process\ncorresponds to the spindodal demixing that occurs during such a transition"
    },
    {
        "anchor": "Multiplicative cross-correlated noise induced escape rate from a\n  metastable state: We present an analytical framework to study the escape rate from a metastable\nstate under the influence of two external multiplicative cross-correlated noise\nprocesses. Starting from a phenomenological stationary Langevin description\nwith multiplicative noise processes, we have investigated the Kramers' theory\nfor activated rate processes in a nonequilibrium open system (one-dimensional\nin nature) driven by two external cross-correlated noise processes which are\nGaussian, stationary and delta correlated. Based on the Fokker-Planck\ndescription in phase space, we then derive the escape rate from a metastable\nstate in the moderate to large friction limit to study the effect of degree of\ncorrelation on the same. By employing numerical simulation in the presence of\nexternal cross-correlated additive and multiplicative noises we check the\nvalidity of our analytical formalism for constant dissipation, which shows a\nsatisfactory agreement between both the approaches for the specific choice of\nnoise processes. It is evident both from analytical development and the\ncorresponding numerical simulation that the enhancement of rate is possible by\nincreasing the degree of correlation of the external fluctuations.",
        "positive": "Thermocapillary flows and interface deformations produced by localized\n  laser heating in confined environment: The deformation of a fluid-fluid interface due to the thermocapillary stress\ninduced by a continuous Gaussian laser wave is investigated analytically. We\nshow that the direction of deformation of the liquid interface strongly depends\non the viscosities and the thicknesses of the involved liquid layers. We first\ninvestigate the case of an interface separating two different liquid layers\nwhile a second part is dedicated to a thin film squeezed by two external layers\nof same liquid. These results are predictive for applications fields where\nlocalized thermocapillary stresses are used to produce flows or to deform\ninterfaces in presence of confinement, such as optofluidics."
    },
    {
        "anchor": "Interplay between polydispersity, inelasticity, and roughness in the\n  freely cooling regime of hard-disk granular gases: A polydisperse granular gas made of inelastic and rough hard disks is\nconsidered. Focus is laid on the kinetic-theory derivation of the partial\nenergy production rates and the total cooling rate as functions of the partial\ndensities and temperatures (both translational and rotational) and of the\nparameters of the mixture (masses, diameters, moments of inertia, and mutual\ncoefficients of normal and tangential restitution). The results are applied to\nthe homogeneous cooling state of the system and the associated nonequipartition\nof energy among the different components and degrees of freedom. It is found\nthat disks typically present a stronger rotational-translational\nnonequipartition but a weaker component-component nonequipartition than\nspheres. A noteworthy \"mimicry\" effect is unveiled, according to which a\npolydisperse gas of disks having common values of the coefficient of\nrestitution and of the reduced moment of inertia can be made indistinguishable\nfrom a monodisperse gas in what concerns the degree of rotational-translational\nenergy nonequipartition. This effect requires the mass of a disk of component\n$i$ to be approximately proportional to $2\\sigma_i+\\langle\\sigma\\rangle$, where\n$\\sigma_i$ is the diameter of the disk and $\\langle\\sigma\\rangle$ is the mean\ndiameter.",
        "positive": "Hierarchies of Critical Points of a Landau-de Gennes Free Energy on\n  Three-Dimensional Cuboids: We investigate critical points of a Landau-de Gennes (LdG) free energy in\nthree-dimensional (3D) cuboids, that model nematic equilibria. We develop a\nhybrid saddle dynamics-based algorithm to efficiently compute solution\nlandscapes of these 3D systems. Our main results concern (a) the construction\nof 3D LdG critical points from a database of 2D LdG critical points and (b)\nstudies of the effects of cross-section size and cuboid height on solution\nlandscapes. In doing so, we discover multiple-layer 3D LdG critical points\nconstructed by stacking 3D critical points on top of each other, novel pathways\nbetween distinct energy minima mediated by 3D LdG critical points and novel\nmetastable escaped solutions, all of which can be tuned for tailor-made static\nand dynamic properties of confined nematic liquid crystal systems in 3D."
    },
    {
        "anchor": "Contractility in an Extensile System: Essentially all biology is active and dynamic. Biological entities\nautonomously sense, com- pute, and respond using energy-coupled ratchets that\ncan produce force and do work. The cytoskeleton, along with its associated\nproteins and motors, is a canonical example of biological active matter, which\nis responsible for cargo transport, cell motility, division, and morphol- ogy.\nPrior work on cytoskeletal active matter systems showed either extensile or\ncontractile dynamics. Here, we demonstrate a cytoskeletal system that can\ncontrol the direction of the network dynamics to be either extensile,\ncontractile, or static depending on the concentration of filaments or transient\ncrosslinkers through systematic variation of the crosslinker or micro- tubule\nconcentrations. Based off these new observations and our previously published\nresults, we created a simple one-dimensional model of the interaction of\nfilaments within a bundle. Despite its simplicity, our model recapitulates the\nobserved activities of our experimental sys- tem, implying that the dynamics of\nour finite networks of bundles are driven by the local filament-filament\ninteractions within the bundle. Finally, we show that contractile phases can\nresult in autonomously motile networks that resemble cells. Our experiments and\nmodel allow us to gain a deeper understanding of cytoskeletal dynamics and\nprovide a stepping stone for designing active, autonomous systems that could\npotentially dynamically switch states.",
        "positive": "Interfaces in partly compatible polymer mixtures: A Monte Carlo\n  simulation approach: The structure of polymer coils near interfaces between coexisting phases of\nsymmetrical polymer mixtures (AB) is discussed, as well as the structure of\nsymmetric diblock copolymers of the same chain length N adsorbed at the\ninterface. The problem is studied by Monte Carlo simulations of the bond\nfluctuation model on the simple cubic lattice, using massively parallel\ncomputers (CRAY T3D). While homopolymer coils in the strong segregation limit\nare oriented parallel to the interface, the diblocks form ``dumbbells''\noriented perpendicular to the interface. However, in the dilute case\n(``mushroom regime'' rather than ``brush regime''), the diblocks are only\nweakly stretched. Distribution functions for monomers at the chain ends and in\nthe center of the polymer are obtained, and a comparison to the self consistent\nfield theory is made."
    },
    {
        "anchor": "Exclusion Zone of Convex Brushes in the Strong-Stretching Limit: We investigate asymptotic properties of long polymers grafted to convex\ncylindrical and spherical surfaces, and, in particular, distribution of chain\nfree ends. The parabolic potential profile, predicted for flat and concave\nbrushes, fails in convex brushes, and chain free ends span only a finite\nfraction of the brush thickness. In this paper, we extend the self-consistent\nmodel developed by Ball, Marko, Milner and Witten to determine the size of the\nexclusion zone, i.e. size of the region of the brush free from chain ends. We\nshow that in the limit of strong stretching, the brush can be described by an\nalternative system of integral equations. This system can be solved exactly in\nthe limit of weakly curved brushes, and numerically for the intermediate to\nstrong curvatures. We find that going from melt state to theta solvent and then\nto marginal solvent decreases relative size of the exclusion zone. These\nrelative differences grow exponentially as the curvature decreases to zero.",
        "positive": "Clusters and collective motions in Brownian vibrators: Using Brownian vibrators, where single particles can undergo Brownian motion\nunder vibration, we experimentally investigated self-organized structures and\ndynamics of quasi-two-dimensional (quasi-2d) granular materials with volume\nfractions $0.111\\le\\phi\\le0.832$. We show rich structures and dynamics in\nhard-disk systems of inelastic particle collisions, with four phases\ncorresponding to cluster fluid, collective fluid, poly-crystal, and crystal.\nWhile poly-crystal and crystal are strikingly similar to the equilibrium hard\ndisks, the first two phases differ substantially from the equilibrium ones and\nthe previous quasi-2d experiments of uniformly driven spheres. Our\ninvestigation provides single-particle-scale evidence that granular materials\nsubject to uniform random forcing are weakly cohesive with complex internal\nstructures and dynamics. Moreover, our experiment shows that large-scale\ncollective motion can arise in a purely repulsive hard-disk system. The\ncollective motion emerges near $\\phi=0.317$, where the most significant\nclusters span half of the system, and disappears near $\\phi=0.713$, around\nwhich the system crystallizes and the melting transition occurs in the\nequilibrium hard disks."
    },
    {
        "anchor": "Classical Nucleation Theory for Active Fluid Phase Separation: Classical nucleation theory (CNT), linking rare nucleation events to the free\nenergy landscape of a growing nucleus, is central to understanding phase-change\nkinetics in passive fluids. Nucleation in non-equilibrium systems is much\nharder to describe because there is no free energy, but instead a\ndynamics-dependent quasi-potential that typically must be found numerically.\nHere we extend CNT to a class of active phase separating systems governed by a\nminimal field-theoretic model (Active Model B+). In the small noise and\nsupersaturation limits that CNT assumes, we compute analytically the\nquasi-potential, and hence nucleation barrier, for liquid-vapor phase\nseparation. Crucially to our results, detailed balance, although broken\nmicroscopically by activity, is restored along the instanton trajectory, which\nin CNT involves the nuclear radius as the sole reaction coordinate.",
        "positive": "Phoretic self-propulsion: a mesoscopic description of reaction dynamics\n  that powers motion: The fabrication of synthetic self-propelled particles and the experimental\ninvestigations of their dynamics have stimulated interest in self-generated\nphoretic effects that propel nano- and micron-scale objects. Theoretical\nmodeling of these phenomena is often based on a continuum description of the\nsolvent for different phoretic propulsion mechanisms, including,\nself-electrophoresis, self-diffusiophoresis and self-thermophoresis. The work\nin this paper considers various types of catalytic chemical reaction at the\nmotor surface and in the bulk fluid that come into play in mesoscopic\ndescriptions of the dynamics. The formulation is illustrated by developing the\nmesoscopic reaction dynamics for exothermic and dissociation reactions that are\nused to power motor motion. The results of simulations of the self-propelled\ndynamics of composite Janus particles by these mechanisms are presented."
    },
    {
        "anchor": "Flattened and wrinkled encapsulated droplets: Shape-morphing induced by\n  gravity and evaporation: We report surprising morphological changes of suspension droplets (containing\nclass II hydrophobin protein HFBI from Trichoderma reesei and water) as they\nevaporate with a contact line pinned on a rigid solid substrate. Both pendant\nand sessile droplets display the formation of an encapsulating elastic film as\nthe bulk concentration of solute reaches a critical value during evaporation,\nbut the morphology of the droplet varies significantly: for sessile droplets,\nthe elastic film ultimately crumples in a nearly flattened area close to the\napex while in pendant droplets, circumferential wrinkling occurs close to the\ncontact line. These different morphologies are understood through a\ngravito-elasto-capillary model that predicts the droplet morphology and the\nonset of shape changes, as well as showing that the influence of the direction\nof gravity remains crucial even for very small droplets (where the effect of\ngravity can normally be neglected). The results pave the way to control droplet\nshape in several engineering and biomedical applications.",
        "positive": "Pathways of mechanical unfolding of FnIII_{10}: low force intermediates: We study the mechanical unfolding pathways of the $FnIII_{10}$ domain of\nfibronectin by means of an Ising--like model, using both constant force and\nconstant velocity protocols. At high forces and high velocities our results are\nconsistent with experiments and previous computational studies. Moreover, the\nsimplicity of the model allows us to probe the biologically relevant low force\nregime, where we predict the existence of two intermediates with very close\nelongations. The unfolding pathway is characterized by stochastic transitions\nbetween these two intermediates."
    },
    {
        "anchor": "Dynamic crossover length in soft-glassy materials: Based upon mesoscale simulations of binary mixtures with very low surface\ntension and positive disjoining pressure (frustration), we measure the\ncorrelation length of the stress field within the flowing mixture, as a\nfunction of the frequency of the applied load. Two scaling regimes are clearly\nidentified, with a sharp crossover between the liquid and solid regions, with\nexponent -1/2 and -1, respectively. The crossover correlation length is shown\nto be closely connected to the typical scale of the coherent excitations of the\ndensity field, whose collective dynamics is shown to be responsible for\nnon-trivial rheological effects including the emergence of yield stress.",
        "positive": "Self-organisation of auto-phoretic suspensions in confined shear flows: Janus phoretic particles exploit chemical energy stored in their environment\nto self-propel. These active particles modify and respond to their hydrodynamic\nand chemical environments, thus giving them a sensibility to external flows and\nother particles. Furthermore, experimental observations and analysis on\nbiological or synthetic active suspensions indicate that hydro-chemical\ninterparticle interactions lead to non-trivial collective behaviour (e.g.,\ncluster formation of phoretic particles or bacterial swarming) and that the\nresponse of the suspensions to shear flows is non-trivial. In fact, it can lead\nto significant reductions in viscosity due to the energy conversion at\nmicroscopic scales. In this work, using simulations of a continuum kinetic\nmodel, we analyse the dynamics and response to shear and confinement of dilute\nsuspensions of chemotactic phoretic particles that reorient and drift toward\nthe chemical solutes released by their neighbours. We show that a 1D transient\nsteady distribution driven by the effect of confinement is a common feature\nconsidered and analyse its stability for varying confinement strength and shear\nrate. In the second step, we consider and discuss, more specifically, the\nfeedback effect on the flow by the particle and the resulting effective\nviscosity of the suspension."
    },
    {
        "anchor": "Nucleation of a new phase on a surface that is changing irreversibly\n  with time: Nucleation of a new phase almost always starts at a surface. This surface is\nalmost always assumed not to change with time. However, surfaces can roughen,\npartially dissolve and change chemically with time. Each of these irreversible\nchanges will change the nucleation rate at the surface, resulting in a\ntime-dependent nucleation rate. Here we use a simple model to show that partial\nsurface dissolution can qualitatively change the nucleation process, in a way\nthat is testable in experiment. The changing surface means that the nucleation\nrate is increasing with time. There is an initial period during which no\nnucleation occurs, followed by relatively rapid nucleation.",
        "positive": "Simultaneous concentration and velocity maps in particle suspensions\n  under shear from rheo-ultrasonic imaging: We extend a previously developed ultrafast ultrasonic technique [Gallot et\nal., Rev. Sci. Instrum. 84, 045107 (2013)] to concentration field measurements\nin non-Brownian particle suspensions under shear. The technique provides access\nto time-resolved concentration maps within the gap of a Taylor-Couette cell\nsimultaneously to local velocity measurements and standard rheological\ncharacterization. Benchmark experiments in homogeneous particle suspensions are\nused to calibrate the system. We then image heterogeneous concentration fields\nthat result from centrifugation effects, from the classical Taylor-Couette\ninstability and from sedimentation or shear-induced resuspension."
    },
    {
        "anchor": "Nonlinear mechanics of rigidifying curves: Thin shells are characterized by a high cost of stretching compared to\nbending. As a result isometries of the midsurface of a shell play a crucial\nrole in their mechanics. In turn, curves with zero normal curvature play a\ncritical role in determining the number and behavior of isometries. In this\npaper, we show how the presence of these curves results in a decrease in the\nnumber of linear isometries. Paradoxically, shells are also known to\ncontinuously fold more easily across these rigidifying curves than other curves\non the surface. We show how including nonlinearities in the strain can explain\nthis phenomena and demonstrate folding isometries with explicit solutions to\nthe nonlinear isometry equations. In addition to explicit solutions, exact\ngeometric arguments are given to validate and guide our analysis in a\ncoordinate free way.",
        "positive": "Viscosity bounds in liquids with different structure and bonding types: Recently, it was realised that liquid viscosity has a lower bound which is\nnearly constant for all liquids and is governed by fundamental physical\nconstants. This was supported by experimental data in noble and molecular\nliquids. Here, we perform large-scale molecular dynamics simulations to\nascertain this bound in two other important liquid types: the ionic molten salt\nsystem LiF and metallic Pb. We find that these ionic and metallic systems\nsimilarly have lower viscosity bounds corresponding to the minimum of kinematic\nviscosity of about 10$^{-7}$ $\\frac{{\\rm m}^2}{\\rm s}$. We show that this\nagrees with experimental data in other systems with different structures and\nbonding types, including noble, molecular, metallic and covalent liquids. This\nexpands the universality of viscosity bounds into the main system types known."
    },
    {
        "anchor": "Dissipative particle dynamics: Dissipative forces from atomistic\n  simulation: We present a novel approach of mapping dissipative particle dynamics (DPD)\ninto classical molecular dynamics. By introducing the invariant volume element\nrepresenting the swarm of atoms we show that the interactions between the\nemerging Brownian quasiparticles arise naturally from its geometric definition\nand include both conservative repulsion and dissipative drag forces. The\nquasiparticles, which are composed of atomistic host solvent rather than being\nsimply immersed in it, provide a link between the atomistic and DPD levels and\na practical route to extract the DPD parameters as direct statistical averages\nover the atomistic host system. The method thus provides the molecular\nfoundations for the mesoscopic DPD. It is illustrated on the example of simple\nmonatomic supercritical fluid demonstrating good agreement in thermodynamic and\ntransport properties calculated for the atomistic system and DPD using the\nobtained parameters.",
        "positive": "Glassy behavior of molecular crystals: A comparison between results from\n  MD-simulation and mode coupling theory: We have investigated the glassy behavior of a molecular crystal built up with\nchloroadamantane molecules. For a simple model of this molecule and a rigid fcc\nlattice a MD simulation was performed from which we obtained the dynamical\norientational correlators $S_{\\lambda \\lambda '}({\\bf{q}},t)$ and the ``self''\ncorrelators $S_{\\lambda \\lambda '}^{(s)}(t)$, with $\\lambda = (\\ell, m)$,\n$\\lambda' = (\\ell', m')$. Our investigations are for the diagonal correlators\n$\\lambda = \\lambda'$. Since the lattice constant decreases with decreasing\ntemperature which leads to an increase of the steric hindrance of the\nmolecules, we find a strong slowing down of the relaxation. It has a high\nsensitivity on $\\lambda$, $\\lambda '$. For most $(\\ell,m)$, there is a two-step\nrelaxation process, but practically not for $(\\ell,m) = (2,1)$, $(3,2)$,\n$(4,1)$ and $(4,3)$. Our results are consistent with the $\\alpha$-relaxation\nscaling laws predicted by mode coupling theory from which we deduce the glass\ntransition temperature $T_c^{MD} \\cong 217K$. From a first principle solution\nof the mode coupling equations we find $T_c^{MCT} \\cong 267K$. Furthermore mode\ncoupling theory reproduces the absence of a two-step relaxation process for\n$(\\ell,m)=(2,1)$, $(3,2)$, $(4,1)$ and $(4,3)$, but underestimates the critical\nnonergodicity parameters by about 50 per cent for all other $(\\ell,m)$. It is\nsuggested that this underestimation originates from the anisotropic crystal\nfield which is not accounted for by mode coupling theory. Our results also\nimply that phonons have no essential influence on the long time relaxation."
    },
    {
        "anchor": "Two dimensional curved disks on a sphere: the evolution of kinetic\n  energy: We put disks on a sphere between two parallels of this sphere. The disks have\nthe curvature of the sphere and interact via a simplified Hertz law. We analyze\nthe behavior of the total kinetic energy of the whole assembly of disks with\nRiemanian geometry and contrarily to flat spaces, this kinetic energy\nincreases. This is due to a non radial component of the resulting velocity\nvector at each interaction between two disks. The study of granular matter in\ntwodimensional curved spaces is therefore not trivial.",
        "positive": "On the existence of a simple yield stress fluid behavior: Materials such as foams, concentrated emulsions, dense suspensions or\ncolloidal gels, are yield stress fluids. Their steady flow behavior,\ncharacterized by standard rheometric techniques, is usually modeled by a\nHerschel-Bulkley law. The emergence of techniques that allow the measurement of\ntheir local flow properties (velocity and volume fraction fields) has led to\nobserve new complex behaviors. It was shown that many of these materials\nexhibit shear banding in a homogeneous shear stress field, which cannot be\naccounted for by the standard steady-state constitutive laws of simple yield\nstress fluids. In some cases, it was also observed that the velocity fields\nunder various conditions cannot be modeled with a single constitutive law and\nthat nonlocal models are needed to describe the flows. Doubt may then be cast\non any macroscopic characterization of such systems, and one may wonder if any\nmaterial behaves in some conditions as a Herschel-Bulkley material. In this\npaper, we address the question of the existence of a simple yield stress fluid\nbehavior. We first review experimental results from the literature and we point\nout the main factors (physical properties, experimental procedure) at the\norigin of flow inhomogeneities and nonlocal effects. It leads us to propose a\nwell-defined procedure to ensure that steady-state bulk properties of the\nmaterials are studied. We use this procedure to investigate yield stress fluid\nflows with MRI techniques. We focus on nonthixotropic dense suspensions of soft\nparticles (foams, concentrated emulsions, Carbopol gels). We show that, as long\nas they are studied in a wide (as compared to the size of the material\nmesoscopic elements) gap geometry, these materials behave as 'simple yield\nstress fluids': they are homogeneous, they do not exhibit steady-state shear\nbanding, and their steady flow behavior in simple shear can be modeled by a\nlocal continuous monotonic constitutive equation which accounts for flows in\nvarious conditions and matches the macroscopic response."
    },
    {
        "anchor": "Steady states of non-axial dipolar rods driven by rotating fields: We investigate a two-dimensional system of magnetic colloids with anisotropic\ngeometry (rods) subjected to an oscillating external magnetic field. The\nstructural and dynamical properties of the steady states are analyzed, by means\nof Langevin Dynamics simulations, as a function of the misalignment of the\nintrinsic magnetic dipole moment of the rods with respect to their axial\ndirection, and also in terms of the strength and rotation frequency of an\nexternal magnetic field. The misalignment of the dipole relative to their axial\ndirection is inspired by recent studies, and this is extremely relevant in the\nmicroscopic aggregation states of the system. The dynamical response of the\nmagnetic rods to the external magnetic field is strongly affected by such a\nmisalignment. Concerning the synchronization between the magnetic rods and the\ndirection of the external magnetic field, we define three distinct regimes of\nsynchronization. A set of steady states diagrams are presented, showing the\nmagnitude and rotation frequency intervals in which the distinct self-organized\nstructures are observed.",
        "positive": "Volume Expansion of Branched Polymers: The excluded volume effects of randomly branched polymers are investigated.\nTo approach this problem we assume the Gaussian distribution of segments around\nthe center of gravity. Once this approximation is introduced, we can make use\nof the same method as employed for linear molecules. By simulating a\nmodel-polymer system, it is found that the excluded volume effects of branched\npolymers are manifested pronouncedly under any conditions from the dilution\nlimit to the melt, including the $\\Theta$ state; every result satisfies the\nrestraining condition: $\\langle s^2\\rangle^{1/2} \\ge N^{1/d}$ in accord with\nour experiences. As a result the Gaussian approximation extracts the essential\nfeatures of the excluded volume effects of branched molecules."
    },
    {
        "anchor": "Magnetism, FeS colloids, and Origins of Life: A number of features of living systems: reversible interactions and weak\nbonds underlying motor-dynamics; gel-sol transitions; cellular connected\nfractal organization; asymmetry in interactions and organization; quantum\ncoherent phenomena; to name some, can have a natural accounting via $physical$\ninteractions, which we therefore seek to incorporate by expanding the horizons\nof `chemistry-only' approaches to the origins of life. It is suggested that the\nmagnetic 'face' of the minerals from the inorganic world, recognized to have\nplayed a pivotal role in initiating Life, may throw light on some of these\nissues. A magnetic environment in the form of rocks in the Hadean Ocean could\nhave enabled the accretion and therefore an ordered confinement of\nsuper-paramagnetic colloids within a structured phase. A moderate H-field can\nhelp magnetic nano-particles to not only overcome thermal fluctuations but also\nharness them. Such controlled dynamics brings in the possibility of accessing\nquantum effects, which together with frustrations in magnetic ordering and\nhysteresis (a natural mechanism for a primitive memory) could throw light on\nthe birth of biological information which, as Abel argues, requires a\ncombination of order and complexity. This scenario gains strength from\nobservations of scale-free framboidal forms of the greigite mineral, with a\nmagnetic basis of assembly. And greigite's metabolic potential plays a key role\nin the mound scenario of Russell and coworkers-an expansion of which is\nsuggested for including magnetism.",
        "positive": "Solid or Liquid ? - Kinetically induced phase transition of a confined\n  liquid: There has been long-standing debate about the physical state and possible\nphase transformations of confined liquids. In this report we show that a model\nconfined liquid can behave both as a Newtonian liquid with very little change\nin its dynamics or as a pseudo-solid depending solely on the {\\it rate} of\napproach of the confining surfaces. Thus, the confined liquid does {\\it not}\nexhibit any confinement induced solidification in thermodynamic equilibrium.\nInstead, solidification is induced kinetically, when the two confining surfaces\nare approached with a minimum critical rate. This critical rate is surprisingly\nslow, of the order of 6 \\AA /s, explaining the frequent observation of\nconfinement induced solidification."
    },
    {
        "anchor": "Behavior of block-polyampholytes near a charged surface: The behavior of polyampholytes near a charged planar surface is studied by\nmeans of Monte Carlo simulations. The investigated polyampholytes are overall\nelectrically neutral and made up of oppositely charged units (called blocks)\nthat are highly charged and of the the same length. The influence of block\nlength and substrate's surface-charge-density on the adsorption behavior is\naddressed. A detailed structural study, including local monomer concentration,\nmonomer mean height, transversal chain size, interface-bond orientation\ncorrelation, is provided. It is demonstrated that adsorption is favored for\nlong enough blocks and/or high enough Coulomb interface-ion couplings. By\nexplicitly measuring the chain size in the bulk, it is shown that the charged\ninterface induces either a swelling or a shrinkage of the transversal dimension\nof the chain depending, in a non trivial manner, on the block length.",
        "positive": "Onset and cessation of motion in hydrodynamically sheared granular beds: We performed molecular dynamics simulations of granular beds driven by a\nmodel hydrodynamic shear flow to elucidate general grain-scale mechanisms that\ndetermine the onset and cessation of sediment transport. By varying the Shields\nnumber (the nondimensional shear stress at the top of the bed) and particle\nReynolds number (the ratio of particle inertia to viscous damping), we explore\nhow variations of the fluid flow rate, particle inertia, and fluid viscosity\naffect the onset and cessation of bed motion. For low to moderate particle\nReynolds numbers, a critical boundary separates mobile and static states.\nTransition times between these states diverge as this boundary is approached\nboth from above and below. At high particle Reynolds number, inertial effects\nbecome dominant, and particle motion can be sustained well below flow rates at\nwhich mobilization of a static bed occurs. We also find that the onset of bed\nmotion (for both low and high particle Reynolds numbers) is described by\nWeibullian weakest-link statistics, and thus is crucially dependent on the\npacking structure of the granular bed, even deep beneath the surface."
    },
    {
        "anchor": "Surface Tension of Electrolyte Interfaces: Ionic Specificity within a\n  Field-Theory Approach: We study the surface tension of ionic solutions at air/water and oil/water\ninterfaces. By using field-theoretical methods and including a finite proximal\nsurface-region with ionic-specific interactions. The free energy is expanded to\nfirst-order in a loop expansion beyond the mean-field result. We calculate the\nexcess surface tension and obtain analytical predictions that reunite the\nOnsager-Samaras pioneering result (which does not agree with experimental\ndata), with the ionic specificity of the Hofmeister series. We derive\nanalytically the surface-tension dependence on the ionic strength, ionic size\nand ion-surface interaction, and show consequently that the Onsager-Samaras\nresult is consistent with the one-loop correction beyond the mean-field result.\nOur theory fits well a wide range of salt concentrations for different\nmonovalent ions using one fit parameter per electrolyte, and reproduces the\nreverse Hofmeister series for anions at the air/water and oil/water interfaces.",
        "positive": "Hydrodynamics of a Micro-Hunter: Chemotactic Scenario: Inspired by bacterial chemotaxis we propose a hydrodynamic molecular scale\nhunter that can swim and find its target. The system is essentially a\nstochastic low Reynolds swimmer with ability to move in two dimensional space\nand sense the local value of the chemical concentration emitted by a target. We\nshow that by adjusting the geometrical and dynamical variables of the swimmer\nwe can always achieve a swimmer that can navigate and search for the region\nwith higher concentration of a chemical emitted from a source. The system\ndiscussed here can also be considered as a theoretical framework for describing\nthe bacterial chemotaxis."
    },
    {
        "anchor": "Orientation, Flow, and Clogging in a Two-Dimensional Hopper: Ellipses\n  vs. Disks: Two-dimensional (2D) hopper flow of disks has been extensively studied. Here,\nwe investigate hopper flow of ellipses with aspect ratio $\\alpha = 2$, and we\ncontrast that behavior to the flow of disks. We use a quasi-2D hopper\ncontaining photoelastic particles to obtain stress/force information. We\nsimultaneously measure the particle motion and stress. We determine several\nproperties, including discharge rates, jamming probabilities, and the number of\nparticles in clogging arches. For both particle types, the size of the opening,\n$D$, relative to the size of particles, $\\ell$ is an important dimensionless\nmeasure. The orientation of the ellipses plays an important role in flow\nrheology and clogging. The alignment of contacting ellipses enhances the\nprobability of forming stable arches. This study offers insight for\napplications involving the flow of granular materials consisting of ellipsoidal\nshapes, and possibly other non-spherical shapes.",
        "positive": "Two-step nucleation in a binary mixture of Patchy Particles: Nucleation in systems with a metastable liquid-gas critical point is the\nprototypical example of a two-step nucleation process, in which the appearance\nof the critical nucleus is preceded by the formation of a liquid-like density\nfluctuation. So far, the majority of studies on colloidal and protein\ncrystallization have focused on one-component systems, and we are lacking a\nclear description of two-step nucleation processes in multicomponent systems,\nwhere critical fluctuations involve coupled density and concentrations\ninhomogeneities. Here, we examine the nucleation process of a binary mixture of\npatchy particles designed to nucleate into a diamond lattice. By combining\nGibbs-ensemble simulations and direct nucleation simulations over a wide range\nof thermodynamic conditions, we are able to pin down the role of the liquid-gas\nmetastable phase diagram on the nucleation process. In particular, we show that\nthe strongest enhancement of crystallization occurs at an azeotropic point with\nthe same stoichiometric composition of the crystal."
    },
    {
        "anchor": "Motile bacteria in a critical fluid mixture: We studied the swimming of \\textit{Escherichia coli} bacteria in the vicinity\nof the critical point in a solution of the non-ionic surfactant\n\\chem{C_{12}E_{5}} in buffer solution. In phase contrast microscopy, each\nswimming cell produces a transient trail behind itself lasting several seconds.\nComparing quantitative image analysis with simulations show that these trails\nare due to local phase re-organisation triggered by differential adsorption.\nThis contrasts with similar trails seen in bacteria swimming in liquid\ncrystals, which are due to shear effects. We show how our trails are\ncontrolled, and use them to probe the structure and dynamics of critical\nfluctuations in the fluid medium.",
        "positive": "A corrected single element Maxwell visco-elastic model: The original Maxwell visco-elastic constitutive model cannot predict the\ncorrect mechanical properties for most fluids. In this work, the model is\ngeneralized with respect to wave-vector and extended with a correction\nfunction. This new model has only two free parameters and avoids the\nattenuation-frequency locking present in the original model. Through molecular\nsimulations it is shown that the model satisfactory predicts the transverse\ndynamics of the binary Lennard-Jones system at different temperatures, as well\nas water and toluene at ambient conditions. From the correction function it is\nshown that the viscous response is significantly reduced compared to the\npredictions from the original model when taking the wave-vector dependency into\naccount. Morover, a temperature dependent characteristic length scale of\nmaximum reduced viscous response is identified."
    },
    {
        "anchor": "Anatomy of triply-periodic network assemblies: Characterizing skeletal\n  and inter-domain surface geometry of block copolymer gyroids: Triply-periodic networks (TPNs), like the well-known gyroid and diamond\nnetwork phases, abound in soft matter assemblies, from block copolymers (BCPs),\nlyotropic liquid crystals and surfactants to functional architectures in\nbiology. While TPNs are, in reality, volume-filling patterns of\nspatially-varying molecular composition, physical and structural models most\noften reduce their structure to lower-dimensional geometric objects: the {\\it\n2D interfaces} between chemical domains; and the {\\it 1D skeletons} that thread\nthrough inter-connected, tubular domains. These lower-dimensional structures\nprovide a useful basis of comparison to idealized geometries based on\ntriply-periodic minimal, or constant-mean curvature surfaces, and shed\nimportant light on the spatially heterogeneous packing of molecular\nconstituents that form the networks. Here, we propose a simple, efficient and\nflexible method to extract a 1D skeleton from 3D volume composition data of\nself-assembled networks. We apply this method to both self-consistent field\ntheory predictions as well as experimental electron microtomography\nreconstructions of the double-gyroid phase of an ABA triblock copolymer. We\nfurther demonstrate how the analysis of 1D skeleton, 2D inter-domain surfaces,\nand combinations therefore, provide physical and structural insight into TPNs,\nacross multiple length scales. Specifically, we propose and compare simple\nmeasures of {\\it network chirality} as well as {\\it domain thickness}, and\nanalyze their spatial and statistical distributions in both ideal (theoretical)\nand non-ideal (experimental) double gyroid assemblies.",
        "positive": "Scaling theory for mechanical critical behavior in fiber networks: As a function of connectivity, spring networks exhibit a critical transition\nbetween floppy and rigid phases at an isostatic threshold. For connectivity\nbelow this threshold, fiber networks were recently shown theoretically to\nexhibit a rigidity transition with corresponding critical signatures as a\nfunction of strain. Experimental collagen networks were also shown to be\nconsistent with these predictions. We develop a scaling theory for this\nstrain-controlled transition. Using a real-space renormalization approach, we\ndetermine relations between the critical exponents governing the transition,\nwhich we verify for the strain-controlled transition using numerical\nsimulations of both triangular lattice-based and packing-derived fiber\nnetworks."
    },
    {
        "anchor": "Unsteady flows and inhomogeneous packing in damp granular heap flows: We experimentally study the transition from steady flow to unsteady flow in a\nquasi-2D granular heap when small amounts of water are added to monodisperse\nglass spheres. Particles flow uniformly down both sides of the heap for low\nwater content, but unsteady flow occurs as the water content increases. The\nunsteady flow mode consists of a non-depositing downslope avalanche and an\nupslope propagating granular jump. The transition from steady to unsteady flow\noccurs when the slope exceeds a critical angle as a result of water-induced\ncohesion. Under unsteady flow conditions, the deposited heap consists of\nloosely packed and densely packed layers, the formation of which is closely\nrelated to the unsteady flow dynamics.",
        "positive": "Molecular dynamics simulations of cRGD-conjugated PEGylated TiO$_2$\n  nanoparticles for targeted photodynamic therapy: The conjugation of high-affinity cRGD-containing peptides is a promising\napproach in nanomedicine to efficiently reduce off-targeting effects and\nenhance the cellular uptake by integrin-overexpressing tumor cells. Herein we\nutilize atomistic molecular dynamics simulations to evaluate key\nstructural-functional parameters of these targeting ligands for an effective\nbinding activity towards $\\alpha_V\\beta_3$ integrins. An increasing number of\ncRGD ligands is conjugated to PEG chains grafted to highly curved TiO$_2$\nnanoparticles to unveil the impact of cRGD density on the ligand's\npresentation, stability, and conformation in an explicit aqueous environment.\nWe find that a low density leads to an optimal spatial presentation of cRGD\nligands out of the \"stealth\" PEGylated layer around the nanosystem, favoring a\nstraight upward orientation and spaced distribution of the targeting ligands in\nthe bulk-water phase. On the contrary, high densities favor clustering and\ninternalization of cRGD ligands in the inner region of the PEGylated layer,\ndriven by a concerted mechanism of enhanced ligand-ligand interactions and\nreduced water accessibility over the ligand's molecular surface. These findings\nstrongly suggest that the ligand density modulation is a key factor in the\ndesign of cRGD-targeting nanodevices to maximize their binding efficiency into\nover-expressed $\\alpha_V\\beta_3$ integrin receptors."
    },
    {
        "anchor": "Charged Plate in Asymmetric Electrolytes: One-loop Renormalization of\n  Surface Charge Density and Debye Length due to Ionic Correlations: The self-consistent field theory (SCFT) is used to study the mean potential\nnear a charged plate inside a $m:-n$ electrolyte. A perturbation series is\ndeveloped in terms of $g = 4 \\pi b/\\ell_{\\rm {\\scriptscriptstyle DB}}$, where\n$b, \\ell_{\\rm{\\scriptscriptstyle DB}}$ are Bjerrum length and {\\em bare} Debye\nlength respectively. To the zeroth order, we obtain nonlinear Poisson-Boltzmann\ntheory. For asymmetric electrolytes ($m \\neq n$), the first order (one-loop)\ncorrection to mean potential contains a {\\em secular term}, which indicates the\nbreakdown of regular perturbation method. Using a renormalizaton group\ntransformation (RG), we remove the secular term and obtain a globally\nwell-behaved one-loop approximation with {\\em a renormalized Debye length} and\n{\\em a renormalized surface charge density}. Furthermore, we find that if the\ncounter-ions are multivalent, the surface charge density is renormalized\nsubstantially {\\em downwards}, and may undergo a change of sign, if the bare\nsurface charge density is sufficiently large.",
        "positive": "Protein-lipid domains in heterogeneous membranes beyond spontaneous\n  curvature effects: We study a model of a lipid bilayer membrane described by two order\nparameters: the chemical composition described using the Gaussian model and the\nspatial configuration described with the elastic deformation model of a\nmembrane with a finite thickness, or equivalently, for an adherent membrane. We\nassume and explain on physical grounds the linear coupling between the two\norder parameters. Using the exact solution, we calculate the correlation\nfunctions and order parameters profiles. We also study the domains that form\naround inclusions on the membrane. We propose and compare six distinct ways to\nquantify the size of such domains. Despite of its simplicity, the model has\nmany interesting features like Fisher-Widom line or two distinct critical\nregions."
    },
    {
        "anchor": "On the presence of a critical detachment angle in gecko spatula peeling\n  -- A numerical investigation using an adhesive friction model: A continuum-based computational contact model is employed to study coupled\nadhesion and friction in gecko spatulae. Nonlinear finite element analysis is\ncarried out to simulate spatula peeling from a rigid substrate. It is shown\nthat the \"frictional adhesion\" behavior, until now only observed from seta to\ntoe levels, is also present at the spatula level. It is shown that for\nsufficiently small spatula pad thickness, the spatula detaches at a constant\nangle known as the critical detachment angle irrespective of the peeling and\nshaft angles. The spatula reaches the same energy states at the jump-off\ncontact point, which directly relates to the invariance of the critical\ndetachment angle. This study also reveals that there is an optimum pad\nthickness associated with the invariance of the critical detachment angle. It\nis further observed that the sliding of the spatula pad is essential for the\ninvariance of the critical detachment angle.",
        "positive": "Comment on \"Field Theory for Amorphous Solids\" by Eric DeGiuli: In a recent pair of papers, Eric DeGiuli has developed a field theory of\nglasses and granular materials based on the Edwards ensemble, extending our\nearlier theoretical framework. In this comment, we address a misconception\nregarding the relation between equiprobability of microstates and a flat\nmeasure in a field theory, which appears in the DeGiuli papers, and has often\nplagued discussions surrounding the Edwards ensemble. We point out that\nmodeling this measure is the challenge addressed in both our earlier work and\nthe recent DeGiuli work. Contrary to what is stated in the the DeGiuli papers,\nwe did not assume a flat measure in our earlier work."
    },
    {
        "anchor": "Predicting Polymer Brush Behavior in Solvents using the\n  Steepest-Entropy-Ascent Quantum Thermodynamic Framework: The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework is\nutilized to study the effects of temperature on polymer brushes. The brushes\nare represented by a discrete energy spectrum and energy degeneracies obtained\nthrough the Replica-Exchange Wang-Landau algorithm. The SEAQT equation of\nmotion is applied to the density of states to establish a unique kinetic path\nfrom an initial thermodynamic state to a stable equilibrium state. The kinetic\npath describes the brush's evolution in state space as it interacts with a\nthermal reservoir. The predicted occupation probabilities along the kinetic\npath are used to determine expected thermodynamic and structural properties.\nThe polymer density profile of a polystyrene brush in cyclohexane solvent is\npredicted using the equation of motion, and it agrees qualitatively with\nexperimental density profiles. The Flory-Huggins parameter chosen to describe\nbrush-solvent interactions affects the solvent distribution in the brush but\nhas minimal impact on the polymer density profile. Three types of\nnon-equilibrium kinetic paths with differing amounts of entropy production are\nconsidered: a heating path, a cooling path, and a heating-cooling path.\nProperties such as tortuosity, radius of gyration, brush density, solvent\ndensity, and brush chain conformations are calculated for each path.",
        "positive": "Forming a cube from a sphere with tetratic order: Composed of square particles, the tetratic phase is characterised by a\nfour-fold symmetry with quasi-long-range orientational order but no\ntranslational order. We construct the elastic free energy for tetratics and\nfind a closed form solution for 1/4-disclinations in planar geometry. Applying\nthe same covariant formalism to a sphere we show analytically that within the\none elastic constant approximation eight +1/4-disclinations favor positions\ndefining the vertices of a cube. The interplay between defect-defect\ninteractions and bending energy results in a flattening of the sphere towards\nsuperspheroids with the symmetry of a cube."
    },
    {
        "anchor": "Cage-jump motion reveals universal dynamics and non-universal structural\n  features in glass forming liquids: The sluggish and heterogeneous dynamics of glass forming liquids is\nfrequently associated to the transient coexistence of two phases of particles,\nrespectively with an high and low mobility. In the absence of a dynamical order\nparameter that acquires a transient bimodal shape, these phases are commonly\nidentified empirically, which makes difficult investigating their relation with\nthe structural properties of the system. Here we show that the distribution of\nsingle particle diffusivities can be accessed within a Continuous Time Random\nWalk description of the intermittent motion, and that this distribution\nacquires a transient bimodal shape in the deeply supercooled regime, thus\nallowing for a clear identification of the two coexisting phase. In a simple\ntwo-dimensional glass forming model, the dynamic phase coexistence is\naccompanied by a striking structural counterpart: the distribution of the\ncrystalline-like order parameter becomes also bimodal on cooling, with\nincreasing overlap between ordered and immobile particles. This simple\nstructural signature is absent in other models, such as the three-dimesional\nKob-Andersen Lennard-Jones mixture, where more sophisticated order parameters\nmight be relevant. In this perspective, the identification of the two dynamical\ncoexisting phases opens the way to deeper investigations of structure-dynamics\ncorrelations.",
        "positive": "Onsager-theory-based dynamic model for nematic phases of bent-core\n  molecules and star molecules: We construct the molecular model and the tensor model for the dynamics of the\nnematic phases of bent-core molecules and star molecules in incompressible\nfluid. We start from the molecular interaction and the molecule--fluid\nfriction, and write down a general formulation based on the molecular shape and\nthe free energy. Then we incorporate an Onsager-theory-based static tensor\nmodel that is determined by the molecular shape. In this way, the terms in the\nmolecular model are fully determined by the molecular shape and expressed by\nphysical parameters. For bent-core molecules and star molecules, the model\nshares the same form, but is different in the coefficients. With the polar\ninteraction and elastic energy taken into account, and the convection and\ndiffusion included both spatially and orientationally, the model is suitable\nfor inhomogeneous flows. We adopt the quasi-equilibrium approximation to derive\nthe tensor model with energy dissipation maintained. Numerical simulation is\ncarried out focusing on the shear flow problem using both the molecular and the\ntensor models. We choose the parameters near the transition region of different\nequilibrium nematic phases and examine the effect of molecular shape on the\nflow modes. The tensor model proves to exhibit all the flow modes found in the\nmolecular model."
    },
    {
        "anchor": "Conformational and Structural Relaxations of Poly(ethylene oxide) and\n  Poly(propylene oxide) Melts: Molecular Dynamics Study of Spatial\n  Heterogeneity, Cooperativity, and Correlated Forward-Backward Motion: Performing molecular dynamics simulations for all-atom models, we\ncharacterize the conformational and structural relaxations of poly(ethylene\noxide) and poly(propylene oxide) melts. The temperature dependence of these\nrelaxation processes deviates from an Arrhenius law for both polymers. We\ndemonstrate that mode-coupling theory captures some aspects of the glassy\nslowdown, but it does not enable a complete explanation of the dynamical\nbehavior. When the temperature is decreased, spatially heterogeneous and\ncooperative translational dynamics are found to become more important for the\nstructural relaxation. Moreover, the transitions between the conformational\nstates cease to obey Poisson statistics. In particular, we show that, at\nsufficiently low temperatures, correlated forward-backward motion is an\nimportant aspect of the conformational relaxation, leading to strongly\nnonexponential distributions for the waiting times of the dihedrals in the\nvarious conformational states",
        "positive": "Growth of Order in An Anisotropic Swift-Hohenberg Model: We have studied the ordering kinetics of a two-dimensional anisotropic\nSwift-Hohenberg (SH) model numerically. The defect structure for this model is\nsimpler than for the isotropic SH model. One finds only dislocations in the\naligned ordering striped system. The motion of these point defects is strongly\ninfluenced by the anisotropic nature of the system. We developed accurate\nnumerical methods for following the trajectories of dislocations. This allows\nus to carry out a detailed statistical analysis of the dynamics of the\ndislocations. The average speeds for the motion of the dislocations in the two\northogonal directions obey power laws in time with different amplitudes but the\nsame exponents. The position and velocity distribution functions are only\nweakly anisotropic."
    },
    {
        "anchor": "Rules essential to water molecular undercoordination: A sequential of concepts developed in last decade has enabled a resolution to\nmultiple anomalies of water ice and its low-dimensionality, particularly.\nDeveloped concepts include the coupled hydrogen bond oscillator pair, segmental\nspecific heat, three-body coupling potentials, quasisolidity, and\nsupersolidity. Resolved anomalies include ice buoyancy, ice slipperiness, water\nskin toughness, supercooling and superheating at the nanoscale, etc. Evidence\nshows consistently that molecular undercoordination shortens the HO bond and\nstiffens its phonon while undercoordination does the OH nonbond contrastingly\nassociated with strong lone pair polarization, which endows the low-dimensional\nwater ice with supersolidity. The supersolid phase is hydrophobic, less dense,\nviscoelastic, thermally more diffusive and stable, having longer electron and\nphonon lifetime. The equal number of lone pairs and protons reserves the\nconfiguration and orientation of the coupled hydrogen bond bonds and restricts\nmolecular rotation and proton hopping, which entitles water the simplest,\nordered, tetrahedrally-coordinated, fluctuating molecular crystal covered with\na supersolid skin. The hydrogen bond segmental cooperativity and specific-heat\ndisparity form the soul dictating the extraordinary adaptivity, reactivity,\nrecoverability, sensitivity of water ice when subjecting to physical\nperturbation. It is recommended that the premise of hydrogen bonding and\nelectronic dynamics would deepen the insight into the core physics and\nchemistry of water ice.",
        "positive": "Memory formation in matter: Memory formation in matter is a theme of broad intellectual relevance; it\nsits at the interdisciplinary crossroads of physics, biology, chemistry, and\ncomputer science. Memory connotes the ability to encode, access, and erase\nsignatures of past history in the state of a system. Once the system has\ncompletely relaxed to thermal equilibrium, it is no longer able to recall\naspects of its evolution. Memory of initial conditions or previous training\nprotocols will be lost. Thus many forms of memory are intrinsically tied to\nfar-from-equilibrium behavior and to transient response to a perturbation. This\ngeneral behavior arises in diverse contexts in condensed matter physics and\nmaterials: phase change memory, shape memory, echoes, memory effects in\nglasses, return-point memory in disordered magnets, as well as related contexts\nin computer science. Yet, as opposed to the situation in biology, there is\ncurrently no common categorization and description of the memory behavior that\nappears to be prevalent throughout condensed-matter systems. Here we focus on\nmaterial memories. We will describe the basic phenomenology of a few of the\nknown behaviors that can be understood as constituting a memory. We hope that\nthis will be a guide towards developing the unifying conceptual underpinnings\nfor a broad understanding of memory effects that appear in materials."
    },
    {
        "anchor": "Beyond Tonks-Girardeau: strongly correlated regime in\n  quasi-one-dimensional Bose gases: We consider a homogeneous 1D Bose gas with contact interactions and large\nattractive coupling constant. This system can be realized in tight waveguides\nby exploiting a confinement induced resonance of the effective 1D scattering\namplitude. By using a variational {\\it ansatz} for the many-body wavefunction,\nwe show that for small densities the gas-like state is stable and the\ncorresponding equation of state is well described by a gas of hard rods. By\ncalculating the compressibility of the system, we provide an estimate of the\ncritical density at which the gas-like state becomes unstable against cluster\nformation. Within the hard-rod model we calculate the one-body density matrix\nand the static structure factor of the gas. The results show that in this\nregime the system is more strongly correlated than a Tonks-Girardeau gas. The\nfrequency of the lowest breathing mode for harmonically trapped systems is also\ndiscussed as a function of the interaction strength.",
        "positive": "Discontinuous shear thickening of dense suspensions under confining\n  pressure: We use 2D numerical simulations to study dense suspensions of non-Brownian\nhard particles using the Critical Load Model (CLM) under constant confining\npressures. This simple model shows discontinuous shear thickening (DST) as the\ntangential forces get activated upon increased shear stresses. By\nparameterizing a simple binary system of frictional and non-frictional\nparticles of different proportions we show that the jamming packing fraction,\nat which the viscosity diverges, is controlled by the fraction of frictional\ncontacts. The viscosity of dense suspensions can thereby be expressed as a\nfunction of the fraction of frictional contacts as well as the packing fraction\nof solid particles. In addition, we show that there exists a simple\nrelationship between the fraction of frictional contacts and the two control\nparameters (under confining pressure): the viscous number J and the ratio\nbetween the repulsive barrier force and confining pressure. Under confining\npressures the viscosity curves are found to depend on the shear protocol, with\nthe possibility of yielding negative dynamic compressibility."
    },
    {
        "anchor": "Brownian granular flows down heaps: We study the avalanche dynamics of a pile of micrometer-sized silica grains\nin water-filled microfluidic drums. Contrary to what is expected for classical\ngranular materials, avalanches do not stop at a finite angle of repose. After a\nfirst rapid phase during which the angle of the pile relaxes to an angle\n$\\theta\\_c$, a creep regime is observed where the pile slowly flows until the\nfree surface reaches the horizontal. This relaxation is logarithmic in time and\nstrongly depends on the ratio between the weight of the grains and the thermal\nagitation (gravitational P\\'eclet number). We propose a simple one-dimensional\nmodel based on Kramer's escape rate to describe these Brownian granular\navalanches, which reproduces the main observations.",
        "positive": "Active-Particle Polarization Without Alignment Forces: Active-particle suspensions exhibit distinct polarization-density patterns in\nactivity landscapes, even without anisotropic particle interactions. Such\npolarization without alignment forces is at work in motility-induced phase\nseparation and betrays intrinsic microscopic activity to mesoscale observers.\nUsing stable long-term confinement of a single hot microswimmer in a dedicated\nforce-free particle trap, we examine the polarized interfacial layer at a\nmotility step and confirm that it does not exert pressure onto the bulk. Our\nobservations are quantitatively explained by an analytical theory that can also\nguide the analysis of more complex geometries and many-body effects."
    },
    {
        "anchor": "Analysis of a Toy Model of Electron \"Splitting\": We examine Maris' recent suggestion that the fission of electron-inhabited\nbubbles in liquid helium may give rise to a new form of electron\nfractionization. We introduce a one-dimensional toy-model--a simplified\nanalogue of the helium system--which may be analyzed using the Born-Oppenheimer\napproximation. We find that none of the model's low-lying energy eigenstates\nhave the form suggested by Maris' computations, in which the bubbles were\ntreated completely classically. Instead, the eigenstates are\nquantum-mechanically entangled superposition states, which the classical\ntreatment overlooks.",
        "positive": "Coupled interactions at the ionic graphene/water interface: We compute ionic free energy adsorption profiles at aqueous graphene\ninterface by developing a self-consistent approach. To do so, we design a\nmicroscopic model for water and put the liquid on an equal footing with the\ngraphene described by its electronic band structure. By evaluating\nprogressively the electronic/dipolar coupled electrostatic interactions, we\nshow that the coupling level including mutual graphene/water screening permits\nto recover remarkably the precision of extensive quantum simulations. We\nfurther derive the potential of mean force evolution of several alkali cations."
    },
    {
        "anchor": "Application of the Eckart frame to soft matter: rotation of star\n  polymers under shear flow: The Eckart co-rotating frame is used to analyze the dynamics of star polymers\nunder shear flow, either in melt or solution and with different types of bonds.\nThis formalism is compared with the standard approach used in many previous\nstudies on polymer dynamics, where an apparent angular velocity $\\omega$ is\nobtained from relation between the tensor of inertia and angular momentum. A\ncommon mistake is to interpret $\\omega$ as the molecular rotation frequency,\nwhich is only valid for rigid-body rotation. The Eckart frame, originally\nformulated to analyze the infrared spectra of small molecules, dissects\ndifferent kinds of displacements: vibrations without angular momentum, pure\nrotation, and vibrational angular momentum (leading to a Coriolis cross-term).\nThe Eckart frame co-rotates with the molecule with an angular frequency\n$\\Omega$ obtained from the Eckart condition for minimal coupling between\nrotation and vibration. The standard and Eckart approaches are compared with a\nstraight description of the star's dynamics taken from the time autocorrelation\nof the monomers positions moving around the molecule's center of mass. This is\nan underdamped oscillatory signal, which can be described by a rotation\nfrequency $\\omega_R$ and a decorrelation rate $\\Gamma$. We consistently find\nthat $\\Omega$ coincides with $\\omega_R$, which determines the characteristic\ntank-treading rotation of the star. By contrast, the apparent angular velocity\n$\\omega < \\Omega$ does not discern between pure rotation and molecular\nvibrations. We believe that the Eckart frame will be useful to unveil the\ndynamics of semiflexible molecules where rotation and deformations are\nentangled, including tumbling, tank-treading motions and breathing modes.",
        "positive": "Rupture of a Biomembrane under Dynamic Surface Tension: How long a fluid membrane vesicle stressed with a steady ramp of micropipette\nlast before rupture? Or conversely, how high the surface tension should be to\nrupture a membrane? To answer these challenging questions we have developed a\ntheoretical framework that allows description and reproduction of Dynamic\nTension Spectroscopy (DTS) observations. The kinetics of the membrane rupture\nunder ramps of surface tension is described as a combination of initial pore\nformation followed by Brownian process of the pore radius crossing the\ntime-dependent energy barrier. We present the formalism and derive (formal)\nanalytical expression of the survival probability describing the fate of the\nmembrane under DTS conditions. Using numerical simulations for the membrane\nprepared in an initial state with a given distribution of times for pore\nnucleation, we have studied the membrane lifetime (or inverse of rupture rate)\nand distribution of membrane surface tension at rupture as a function of\nmembrane characteristics like pore nucleation rate, the energy barrier to\nfailure and tension loading rate. It is found that simulations reproduce main\nfeatures of the experimental data, particularly, the pore nucleation and pore\nsize diffusion controlled limits of membrane rupture dynamics. This approach\ncan also be applied to processes of permeation and pore opening in membranes\n(electroporation, membrane disruption by antimicrobial peptides, vesicle\nfusion)."
    },
    {
        "anchor": "Air fluidized balls in a background of smaller beads: We report on quasi-two-dimensional granular systems in which either one or\ntwo large balls is fluidized by an upflow of air in the presence of a\nbackground of several hundred smaller beads. A single large ball is observed to\npropel ballistically in nearly circular orbits, in direct contrast to the\nBrownian behavior of a large ball fluidized in the absence of this background.\nFurther, the large ball motion satisfies a Langevin equation with an additional\nspeed-dependent force acting in the direction of motion. This results in a\nnon-zero average speed of the large ball that is an order of magnitude faster\nthan the root mean square speed of the background balls. Two large balls\nfluidized in the absence of the small-bead background experience a repulsive\nforce depending only on the separation of the two balls. With the background\nbeads present, by contrast, the ball-ball interaction becomes\nvelocity-dependent and attractive. The attraction is long-ranged and\ninconsistent with a depletion model; instead, it is mediated by local\nfluctuations in the density of the background beads which depends on the large\nballs' motion.",
        "positive": "Comment on \"Simulations of ionization equilibria in weak polyelectrolyte\n  solutions and gels\" by J. Landsgesell, L. Nov\u00e1, O. Rud, F. Uhl\u00edk, D.\n  Sean, P. Hebbeker, C. Holm and P. Ko\\v sovan, Soft Matter, 2019,15, 1155-1185: In a recent review~Landsgesell et al., Soft Matter {\\bf 15}, 1155 (2019)\nstated that $\\text{pH} - \\text{pK}_a$ is a ``universal parameter\" for titrating\nsystems. We show that this is not the case. This broken symmetry has important\nimplications for constant pH (cpH) simulations. In particular, we show that for\nconcentrated suspensions the error resulting from the use of cpH algorithm\ndescribed by Landsgesell et al. is very significant, even for suspension\ncontaining 1:1 electrolyte. We show how to modify the cpH algorithm to account\nfor the grand-canonical nature of the cpH simulations and for the charge\nneutrality requirement."
    },
    {
        "anchor": "Nonlinear Statistical Mechanics Drives Intrinsic Electrostriction and\n  Volumetric Torque in Polymer Networks: Statistical mechanics is an important tool for understanding polymer\nelectroelasticity because the elasticity of polymers is primarily due to\nentropy. However, a common approach for the statistical mechanics of polymer\nchains, the Gaussian chain approximation, misses key physics. By considering\nthe nonlinearities of the problem, we show a strong coupling between the\ndeformation of a polymer chain and its dielectric response; that is, its net\ndipole. When chains with this coupling are cross-linked in an elastomer network\nand an electric field is applied, the field breaks the symmetry of the\nelastomer's elastic properties, and, combined with electrostatic torque and\nincompressibility, leads to intrinsic electrostriction. Conversely, deformation\ncan break the symmetry of the dielectric response leading to volumetric torque\n(i.e., a couple stress or torque per unit volume) and asymmetric actuation.\nBoth phenomena have important implications for designing high-efficiency soft\nactuators and soft electroactive materials; and the presence of mechanisms for\nvolumetric torque, in particular, can be used to develop higher degree of\nfreedom actuators and to achieve bioinspired locomotion.",
        "positive": "Direct route to reproducing pair distribution functions with\n  coarse-grained models via transformed atomistic cross correlations: Coarse-grained (CG) models are often parametrized to reproduce\none-dimensional structural correlation functions of an atomically-detailed\nmodel along the degrees of freedom governing each interaction potential. While\ncross correlations between these degrees of freedom inform the optimal set of\ninteraction parameters, the correlations generated from the higher-resolution\nsimulations are often too complex to act as an accurate proxy for the CG\ncorrelations. Instead, the most popular methods determine the interaction\nparameters iteratively, while assuming that individual interactions are\nuncorrelated. While these iterative methods have been validated for a wide\nrange of systems, they also have disadvantages when parametrizing models for\nmulti-component systems or when refining previously established models to\nbetter reproduce particular structural features. In this work, we propose two\ndistinct approaches for the direct (i.e., non-iterative) parametrization of a\nCG model by adjusting the high-resolution cross correlations of an atomistic\nmodel in order to more accurately reflect correlations that will be generated\nby the resulting CG model. The derived models more accurately describe the\nlow-order structural features of the underlying AA model, while necessarily\ngenerating inherently distinct cross correlations compared with the\natomically-detailed reference model. We demonstrate the proposed methods for a\none-site-per-molecule representation of liquid water, where pairwise\ninteractions are incapable of reproducing the true tetrahedral solvation\nstructure. We then investigate the precise role that distinct cross-correlation\nfeatures play in determining the correct pair correlation functions, evaluating\nthe importance of the placement of correlation features as well as the balance\nbetween features appearing in different solvation shells."
    },
    {
        "anchor": "Bridging and depletion mechanisms in colloid-colloid effective\n  interactions: A reentrant phase diagram: A general class of nonadditive sticky-hard-sphere binary mixtures, where\nsmall and large spheres represent the solvent and the solute, respectively, is\nintroduced. The solute-solute and solvent-solvent interactions are of\nhard-sphere type, while the solute-solvent interactions are of\nsticky-hard-sphere type with tunable degrees of size nonadditivity and\nstickiness. Two particular and complementary limits are studied using\nanalytical and semi-analytical tools. The first case is characterized by zero\nnonadditivity, lending itself to a Percus-Yevick approximate solution from\nwhich the impact of stickiness on the spinodal curves and on the effective\nsolute-solute potential is analyzed. In the opposite nonadditive case, the\nsolvent-solvent diameter is zero and the model can then be reckoned as an\nextension of the well-known Asakura-Oosawa model with additional sticky\nsolute-solvent interaction. This latter model has the property that its exact\neffective one-component problem involves only solute-solute pair potentials for\nsize ratios such that a solvent particle fits inside the interstitial region of\nthree touching solutes. In particular, we explicitly identify the three\ncompeting physical mechanisms (depletion, pulling, and bridging) giving rise to\nthe effective interaction. Some remarks on the phase diagram of these two\ncomplementary models are also addressed through the use of the Noro-Frenkel\ncriterion and a first-order perturbation analysis. Our findings suggest\nreentrance of the fluid-fluid instability as solvent density (in the first\nmodel) or adhesion (in the second model) is varied. Some perspectives in terms\nof the interpretation of recent experimental studies of microgels adsorbed onto\nlarge polystyrene particles are discussed.",
        "positive": "A thermodynamically consistent constitutive equation describing polymer\n  disentanglement under flow: We derive a thermodynamically consistent framework for incorporating\nentanglement dynamics into constitutive equations for flowing polymer melts. We\nuse this to combine the convected constraint release (CCR) dynamics of\nIanniruberto-Marriccui into a finitely-extensible version of the Rolie-Poly\nmodel, and also include an anisotropic mobility as in the Giesekus model. The\nreversible dynamics are obtained from a free energy that describes both a\nfinitely-extensible conformation tensor and an ideal gas of entanglements along\nthe chain. The dissipative dynamics give rise to coupled kinetic equations for\nthe conformation tensor and entanglements, whose coupling terms describe\nshear-induced disentanglement. The relaxation dynamics of the conformation\ntensor follow the GLaMM and Rolie-Poly models, and account for reptation,\nretraction and CCR. We propose that the relaxation time $\\tau_\\nu$ for\nentanglement recovery is proportional to the Rouse time $\\tau_R$ which governs\npolymer stretch within the tube. This which matches recent molecular dynamics\nsimulations, and corresponds to relaxing the entanglement number before the\nentire polymer anisotropy has relaxed on the longer reptation time $\\tau_d$.\nOur model suggests that claimed signatures of slow re-entanglement on the\nreptation time in step-strain experiments may be interpreted as arising from\nanisotropies in reptation dynamics."
    },
    {
        "anchor": "The tubular phase of self-avoiding anisotropic crystalline membranes: We analyze the tubular phase of self-avoiding anisotropic crystalline\nmembranes. A careful analysis using renormalization group arguments together\nwith symmetry requirements motivates the simplest form of the large-distance\nfree energy describing fluctuations of tubular configurations. The\nnon-self-avoiding limit of the model is shown to be exactly solvable. For the\nfull self-avoiding model we compute the critical exponents using an\nepsilon-expansion about the upper critical embedding dimension for general\ninternal dimension D and embedding dimension d. We then exhibit various methods\nfor reliably extrapolating to the physical point (D=2,d=3). Our most accurate\nestimates are nu=0.62 for the Flory exponent and zeta=0.80 for the roughness\nexponent.",
        "positive": "Optimal Entanglement of Polymers Promotes Formation of Highly Oriented\n  Fibers: Polymer fibers consist of macromolecules oriented along the fiber axis.\nBetter alignment of chains leads to an increased strength of the fiber. It is\nbelieved that the key factor preventing formation of a perfectly oriented fiber\nis entanglement of polymers. We performed large-scale computer simulations of\nuniaxial stretching of semicrystalline ultrahigh molecular weight polyethylene.\nWe discovered that there is an optimal number of entanglements per\nmacromolecule necessary to maximize chain orientation in a fiber. Polymers that\nwere entangled too strongly formed less oriented fibers. On the other hand,\nwhen polymers had too few entanglements per chain, they disentangled during\nstretching, and the strong fiber was not formed. We constructed a microscopic\nanalytical theory describing both the fiber formation and disentanglement\nprocesses. Our work presents a novel view on the role of entanglements during\nfiber production and predicts the existence of a single universal optimal\nnumber of entanglements per chain maximizing the fiber quality: approximately\n$10^2$ entanglements."
    },
    {
        "anchor": "On the conformational structure of a stiff homopolymer: In this paper we complete the study of the phase diagram and conformational\nstates of a stiff homopolymer. It is known that folding of a sufficiently stiff\nchain results in formation of a torus. We find that the phase diagram obtained\nfrom the Gaussian variational treatment actually contains not one, but several\ndistinct toroidal states distinguished by the winding number. Such states are\nseparated by first order transition curves terminating in critical points at\nlow values of the stiffness. These findings are further supported by\noff-lattice Monte Carlo simulation. Moreover, the simulation shows that the\nkinetics of folding of a stiff chain passes through various metastable states\ncorresponding to hairpin conformations with abrupt U-turns.",
        "positive": "Simulating Particle Dispersions in Nematic Liquid-Crystal Solvents: A new method is presented for mesoscopic simulations of particle dispersions\nin nematic liquid crystal solvents. It allows efficient first-principle\nsimulations of the dispersions involving many particles with many-body\ninteractions mediated by the solvents. A simple demonstration is shown for the\naggregation process of a two dimentional dispersion."
    },
    {
        "anchor": "Maier-Saupe model for a mixture of uniaxial and biaxial molecules: We introduce shape fluctuations in a liquid-crystalline system by considering\nan elementary Maier--Saupe lattice model for a mixture of uniaxial and biaxial\nmolecules. Shape variables are treated in the annealed (thermalized) limit. We\nanalyze the thermodynamic properties of this system in terms of temperature\n$T$, concentration $c$ of intrinsically biaxial molecules, and a parameter\n$\\Delta$ associated with the degree of biaxiality of the molecules. At the\nmean-field level, we use standard techniques of statistical mechanics to draw\nglobal phase diagrams, which are shown to display a rich structure, including\nuniaxial and biaxial nematic phases, a reentrant ordered region, and many\ndistinct multicritical points. Also, we use the formalism to write an expansion\nof the free energy in order to make contact with the Landau--de Gennes theory\nof nematic phase transitions.",
        "positive": "Richtmyer-Meshkov Instability of a Liquid-Gas Interface Driven by a\n  Cylindrical Imploding Pressure Wave: The compression of a cylindrical gas bubble by an imploding molten lead (Pb)\nshell may be accompanied by the development of the Richtmyer-Meshkov (RM)\ninstability at the liquid-gas interface due to the initial imperfection of the\ninterface. A converging pressure wave impinging upon the interface causes a\nshell of liquid to detach and continue to travel inwards, compressing the gas\nbubble. The efficiency of compression and collapse evolution can be affected by\ndevelopment of the RM instability. Investigations have been performed in the\nregime of extreme Atwood number $A=-1$ with the additional complexity of\nmodeling liquid cavitation in the working fluid. Simulations have been carried\nout using the open source CFD software OpenFOAM on a set of parameters relevant\nto the prototype compression system under development at General Fusion Inc.\nfor use as a Magnetized Target Fusion (MTF) driver.\n  After validating the numerical setup in planar geometry, simulations have\nbeen carried out in 2D cylindrical geometry for both initially smooth and\nperturbed interfaces. Where possible, results have been validated against\nexisting theoretical models and very good agreement has been found. While our\nmain focus is on the effects of initial perturbation amplitude and azimuthal\nmode number, we also address differences between this problem and those usually\nconsidered, such as RM instability at an interface between two gases with a\nmoderate density ratio. One important difference is the formation of narrow\nmolten lead jets rapidly propagating inwards during the final stages of the\ncollapse. Jet behaviour has been observed for a range of azimuthal mode numbers\nand perturbation amplitudes."
    },
    {
        "anchor": "Cooperativity flows and Shear-Bandings: a statistical field theory\n  approach: Cooperativity effects have been proposed to explain the non-local rheology in\nthe dynamics of soft jammed systems. Based on the analysis of the free-energy\nmodel proposed by L. Bocquet, A. Colin \\& A. Ajdari ({\\em Phys. Rev. Lett.}\n{\\bf 103}, 036001 (2009)), we show that cooperativity effects resulting from\nthe non-local nature of the fluidity (inverse viscosity), are intimately\nrelated to the emergence of shear-banding configurations. This connection\nmaterializes through the onset of inhomogeneous compact solutions (compactons),\nwherein the fluidity is confined to finite-support subregions of the flow and\nstrictly zero elsewhere. Compactons coexistence with regions of zero fluidity\n(\"non-flowing vacuum\") is shown to be stabilized by the presence of mechanical\nnoise, which ultimately shapes up the equilibrium distribution of the fluidity\nfield, the latter acting as an order parameter for the flow-noflow transitions\noccurring in the material.",
        "positive": "Revisiting the composition dependence of the properties of\n  water-dimethyl sulfoxide liquid mixtures. Molecular dynamics computer\n  simulations: We have revisited the composition dependence of principal properties of\nliquid water-DMSO mixtures by using the isobaric-isothermal molecular dynamics\ncomputer simulations. A set of non-polarizable semi-flexible models for the\nDMSO molecule combined with the TIP4P-2005 and TIP4P/$\\varepsilon$ water models\nis considered. We restrict calculations to atmospheric pressure, 0.1013 MPa,\nand room temperature, 298.15 K. Composition trends of density, excess mixing\nvolume and excess mixing enthalpy, partial molar volumes and partial molar\nenthalpies of species, apparent molar volumes are reported. Besides, we explore\ncomposition trends of the self-diffusion of species, the static dielectric\nconstant and the surface tension. Evolution of the microscopic structure of the\nmixture with composition is analyzed in terms of radial distributions\nfunctions, coordination numbers and the fractions of hydrogen-bonded molecules.\nWe intend to capture the peculiarities of mixing the species in the mixture\nupon the DMSO molar fraction and the anomalous behaviors, if manifested in each\nof the properties under study. The quality of several combinations of the\nmodels for species is evaluated in detail to establish the possibility of\nnecessary improvements."
    },
    {
        "anchor": "A Simple Tensorial Theory of Smectic C Liquid Crystals: The smectic C (smC) phase represents a unique class of liquid crystal phases\ncharacterised by the layered arrangement of molecules with tilted orientations\nwith respect to layer normals. Building upon the real-valued tensorial smectic\nA (smA) model in [Xia et al., PRL, 126, 177801 (2021)], we propose a new\ncontinuous mathematical model for smC (and smA) by introducing a novel coupling\nterm between the real tensor containing orientational information and density\nvariation, to control the tilt angle between directors and the layer normal\n(the tilt angle is zero for smA and nonzero for smC). To validate our proposed\nmodel, we conduct a series of two- and three-dimensional numerical experiments\nthat account for typical structures in smectics: chevron patterns, defects,\ndislocations and toroidal focal conic domains (TFCDs). These results also\nreveal the phenomenological differences between smA and smC configurations.",
        "positive": "Surface Pressure of Charged Colloids at the Air/Water Interface: Charged colloidal monolayers at the interface between water and air (or oil)\nare used in a large number of chemical, physical and biological applications.\nAlthough a considerable experimental and theoretical effort has been devoted in\nthe past few decades to investigate such monolayers, some of their fundamental\nproperties are not yet fully understood. In this paper, we model charged\ncolloidal monolayers as a continuum layer of finite thickness, with separate\ncharge distribution on the water and air sides. The electrostatic surface\nfree-energy and surface pressure are calculated via the charging method and\nwithin the Debye-H{\\\"u}ckel approximation. We obtain the dependence of surface\npressure on several system parameters: the monolayer thickness, its distinct\ndielectric permittivity, and the ionic strength of the aqueous subphase. The\nsurface pressure scaling with the area per particle, ${a}$, is found to be\nbetween ${a}^{-2}$ in the close-packing limit, and ${a}^{-5/2}$ in the\nloose-packing limit. In general, it is found that the surface-pressure is\nstrongly influenced by charges on the air-side of the colloids. However, when\nthe larger charge resides on the water-side, a more subtle dependence on salt\nconcentration emerges. This corrects a common assumption that the charges on\nthe water-side can \\textit{always} be neglected due to screening. Finally,\nusing a single fit parameter, our theory is found to fit well the experimental\ndata for strong to intermediate strength electrolytes. We postulate that an\nanomalous scaling of $a^{-3/2}$, recently observed in low ionic concentrations,\ncannot be accounted for within a linear theory, and its explanation requires a\nfully-nonlinear analysis."
    },
    {
        "anchor": "Stabilization of frictional sliding by normal load modulation: A\n  bifurcation analysis: This paper presents the stability analysis of a system sliding at low\nvelocities ($< 100 \\mu$m.s$^{-1}$) under a periodically modulated normal load,\npreserving interfacial contact. Experiments clearly evidence that normal\nvibrations generally stabilize the system against stick-slip oscillations, at\nleast for a modulation frequency much larger than the stick-slip one. The\nmechanical model of Bureau {\\it et al.} (2000), validated on the steady-state\nresponse of the system, is used to map its stability diagram. The model takes\nexplicitly into account the finite shear stiffness of the load-bearing\nasperities, in addition to a classical state- and rate-dependent friction\nforce. The numerical results are in excellent quantitative agreement with the\nexperimental data obtained from a multicontact frictional system between glassy\npolymer materials. Simulations at larger amplitude of modulation (typically 20%\nof the mean normal load) suggest that the non-linear coupling between normal\nand sliding motion could have a destabilizing effect in restricted regions of\nthe parameter space.",
        "positive": "Relaxation with long-period oscillation in defect turbulence of planar\n  nematic liquid crystals: Through experiments, we studied defect turbulence, a type of spatiotemporal\nchaos in planar systems of nematic liquid crystals, to clarify the chaotic\nadvection of weak turbulence. In planar systems of large aspect ratio,\nstructural relaxation which is characterized by the dynamic structure factor\nexhibits a long-period oscillation that is described well by a combination of a\nsimple exponential relaxation and underdamped oscillation. The simple\nrelaxation arises as a result of the roll modulation while the damped\noscillation is manifest in the repetitive gliding of defect pairs in a local\narea. Each relaxation is derived analytically by the projection operator method\nthat separates turbulent transport into a macroscopic contribution and\nfluctuations. The analysis proposes that the two relaxations are not\ncorrelated. The nonthermal fluctuations of defect turbulence are consequently\nseparated into two independent Markov processes. Our approach sheds light on\ndiversity and universality from a unified viewpoint for weak turbulence."
    },
    {
        "anchor": "Theory of tunable pH sensitive vesicles of anionic and cationic lipids\n  or anionic and neutral lipids: The design of vesicles which become unstable at an easily tuned value of pH\nis of great interest for targeted drug delivery. We present a microscopic\ntheory for two forms of such vesicles. A model of lipids introduced by us\npreviously is applied to a system of ionizable, anionic lipid, and permanently\ncharged, cationic lipid. We calculate the pH at which the lamellar phase\nbecomes unstable with respect to an inverted hexagonal one, a value which\ndepends continuously on the system composition. Identifying this instability\nwith that displayed by unilamellar vesicles undergoing fusion, we obtain very\ngood agreement with the recent experimental data of Hafez et al., Biophys. J.\n2000 79: 1438-1446, on the pH at which fusion occurs vs. vesicle composition.\nWe explicate the mechanism in terms of the role of the counter ions. This\nunderstanding suggests that a system of a neutral, non lamellar forming lipid\nstabilized by an anionic lipid would serve equally well for preparing tunable,\npH sensitive vesicles. Our calculations confirm this. Further, we show that\nboth forms of vesicle have the desirable feature of exhibiting a regime in\nwhich the pH at instability is a rapidly varying function of the vesicle\ncomposition.",
        "positive": "Filamin cross-linked semiflexible networks: Fragility under strain: The semiflexible F-actin network of the cytoskeleton is cross-linked by a\nvariety of proteins including filamin, which contain Ig-domains that unfold\nunder applied tension. We examine a simple semiflexible network model\ncross-linked by such unfolding linkers that captures the main mechanical\nfeatures of F-actin networks cross-linked by filamin proteins and show that\nunder sufficiently high strain the network spontaneously self-organizes so that\nan appreciable fraction of the filamin cross-linkers are at the threshold of\ndomain unfolding. We propose an explanation of this organization based on a\nmean-field model and suggest a qualitative experimental signature of this type\nof network reorganization under applied strain that may be observable in\nintracellular microrheology experiments of Crocker et al."
    },
    {
        "anchor": "Effective viscosity of a suspension of flagellar beating microswimmers:\n  Three-dimensional modeling: Micro-organisms usually can swim in their liquid environment by flagellar or\nciliary beating. In this numerical work, we analyze the influence of flagellar\nbeating on the orbits of a swimming cell in a shear flow. We also calculate the\neffect of the flagellar beating on the rheology of a dilute suspension of\nmicro-swimmers. A three-dimensional model is proposed for Chlamydomonas\nReinhardtii swimming with a breaststroke-like beating of two anterior flagella\nmodeled by two counter-rotating fore beads. The active swimmer model reveals\nunusual angular orbits in a linear shear flow. Namely, the swimmer sustains\norientations transiently across the flow. Such behavior is a result of the\ninterplay between shear flow and swimmer's periodic beating motion of flagella\nwhich exert internal torques on the cell body. This peculiar behavior has some\nsignificant consequences on the rheological properties of the suspension. We\ncalculate the Einstein's viscosity of the suspension composed of such isolated\nmodeled microswimmers (dilute case) in a shear flow. We use numerical\nsimulations based on a Rotne-Prager like approximation for hydrodynamic\ninteraction between simplified flagella and the cell body. The results show an\nincreased intrinsic viscosity for active swimmer suspensions in comparison to\nnon-active ones as well as a shear thinning behavior in accordance with\nprevious experimental measurements [Phys. Rev. Lett. 104 , 098102 (2010)].",
        "positive": "Correlation-induced DNA adsorption on like-charged membranes: The adsorption of DNA or other polyelectrolyte molecules on charged membranes\nis a recurrent motif in soft matter and bionanotechnological systems. Two\ntypical situations encountered are the deposition of single DNA chains onto\nsubstrates for further analysis, e.g., by force microscopy, or the pulling of\npolyelectrolytes into membrane nanopores, as in sequencing applications. In\nthis paper, we present a theoretical analysis of such scenarios based on the\nself-consistent field theory approach, which allows us to address the important\neffect of charge correlations. We calculate the grand potential of a stiff\npolyelectrolyte immersed in an electrolyte in contact with a negatively charged\ndielectric membrane. For the sake of conciseness, we neglect conformational\npolymer fluctuations and model the molecule as a rigid charged line. At\nstrongly charged membranes, the adsorbed counterions enhance the screening\nability of the interfacial region. In the presence of highly charged polymers\nsuch as double-stranded DNA molecules close to the membrane, this enhanced\ninterfacial screening dominates the mean-field level DNA-membrane repulsion and\nresults in the adsorption of the DNA molecule to the surface. This picture\nprovides a simple explanation for the recently observed DNA binding onto\nsimilarly charged substrates [G. L.-Caballero et al., Soft Matter 10, 2805\n(2014)] and points out charge correlations as a non-negligible ingredient of\npolymer-surface interactions."
    },
    {
        "anchor": "Polarization and decoherence in a two-component Bose-Einstein Condensate: We theoretically investigate polarization properties of a two-component\nBose-Einstein condensate (BEC) and influence of decoherence induced by\nenvironment on BEC polarization through introducing four BEC Stokes operators\nwhich are quantum analog of the classical Stokes parameters for a light field.\nBEC polarization states can be geometrically described by a Poincar\\'{e} sphere\ndefined by expectation values of BEC Stokes operators. Without decoherence, it\nis shown that nonlinear inter-atomic interactions in the BEC induce periodic\npolarization oscillations whose periods depend on the difference between\nself-interaction in each component and inter-component interaction strengths.\nIn particular, when inter-atomic nonlinear self-interaction in each BEC\ncomponent equals inter-component nonlinear interaction, Stokes vector\nassociated with Stokes operators precesses around a fixed axis in the dynamic\nevolution of the BEC. The value of the processing frequency is determined by\nthe strength of the linear coupling between two components of the BEC. When\ndecoherence is involved, we find each component of the Stokes vector decays\nwhich implies that decoherence depolarizes the BEC.",
        "positive": "My model, it has three layers: a reduced model of the smectic transition\n  in two dimensions: My model, it has three layers, Three layers is nematic. And had it just two\nlayers, it would be a smectic.\n  We study a reduced model of the smectic transition in two dimensions where\nthe particles occupy three equally spaced layers. The role of particle geometry\ncomes in through the interactions between particles on the central layer and\nthose above and below. The system is understood to be smectic when the central\nlayer is empty, and nematic when all three are equally occupied. It is possible\nto compute the free energies of these states exactly. We find that the free\nenergy of the nematic can only exceed that of the smectic if the particle tips\nare sufficiently wide, mirroring the fact that ellipsoids do not make a smectic\nbut sphero-cylinders do."
    },
    {
        "anchor": "Comparison of compression vs shearing near jamming, for a simple model\n  of athermal frictionless disks in suspension: Using a simplified model for a non-Brownian suspension, we numerically study\nthe response of athermal, overdamped, frictionless disks in two dimensions to\nisotropic and uniaxial compression, as well as to pure {\\color{black}and\nsimple} shearing, all at finite constant strain rates $\\dot\\epsilon$. We show\nthat isotropic and uniaxial compression result in the same jamming packing\nfraction $\\phi_J$, while pure shear and simple shear induced jamming occurs at\na slightly higher $\\phi_J^*$, consistent with that found previously for simple\nshearing. A critical scaling analysis of pure shearing gives critical exponents\nconsistent with those previously found for both isotropic compression and\nsimple shearing. Using orientational order parameters for contact bond\ndirections, we compare the anisotropy of the force and contact networks at both\nlowest nematic order, as well as higher $2n$-fold order.",
        "positive": "A theory for the effect of patch / non-patch attractions on the\n  self-assembly of patchy colloids: In this paper, we develop a thermodynamic perturbation theory to describe the\nself-assembly of patchy colloids which exhibit both patch-patch attractions as\nwell as patch / non-patch attractions. That is, patches attract other patches\nas well as the no patch region. In general these attractions operate on\ndifferent energy scales, which allows for controlled self-assembly as well as\nanomalous phase behavior. As an application we apply the model to the study of\nliquid water."
    },
    {
        "anchor": "Spontaneous Micro Flocking of Active Inertial Particles without\n  Alignment Interaction: Observing spontaneous velocity ordering or flocking during motility induced\nphase separation (MIPS) in a system of spherical active Brownian particles\nwithout alignment interaction is challenging. We take up this problem by\nperforming simulations of spherical active inertial particles with purely\nrepulsive potential in presence of thermal noise and absence of any explicit\nalignment interaction. Our results not only show the presence of MIPS, but also\nreveal a micro-flocking transition. We characterize this transition in terms of\na velocity order parameter as well as a characteristic length scale derived\nfrom the spatial correlation of the velocities.",
        "positive": "Reaction-induced molecular dancing and boosted diffusion of enzymes: A novel mechanism of reaction-induced active molecular motion, not involving\nany kind of self-propulsion, is proposed and analyzed. Because of the momentum\nexchange with the surrounding solvent, conformational transitions in\nmechano-chemical enzymes are accompanied by motions of their centers of mass.\nAs we show, in combination with rotational diffusion, such repeated reciprocal\nmotions generate an additional random walk - or molecular dancing - and hence\nboost translational diffusion of an enzyme. A systematic theory of this\nphenomenon is developed, using as an example a simple enzyme model of a rigid\ntwo-state dumbbell. To support the analysis, numerical simulations are\nperformed. Our conclusion is that the phenomenon of molecular dancing could\nunderlie the observations of reaction-induced diffusion enhancement in enzymes.\nMajor experimental findings, such as the occurrence of leaps, the\nanti-chemotaxis, the linear dependence on the reaction turnover rate and on the\nrate of energy supply, become thus explained. Moreover, the dancing behavior is\npossible in other systems, natural and synthetic, too. In the future,\ninteresting biotechnology applications may be developed using such effects."
    },
    {
        "anchor": "Osmosis with active solutes: Despite much current interest in active matter, little is known about osmosis\nin active systems. Using molecular dynamics simulations, we investigate how\nactive solutes perturb osmotic steady states. We find that solute activity\nincreases the osmotic pressure, and can also expel solvent from the solution -\ni.e. cause reverse osmosis. The latter effect cannot be described by an\neffective temperature, but can be reproduced by mapping the active solution\nonto a passive one with the same degree of local structuring as the passive\nsolvent component. Our results provide a basic framework for understanding\nactive osmosis, and suggest that activity-induced structuring of the passive\ncomponent may play a key role in the physics of active-passive mixtures.",
        "positive": "Spontaneous formation of helical states in polymer chains via molecular\n  dynamics simulation: Molecular process of polymer collapse was reproduced by isothermal molecular\ndynamics simulation. The initial polymer chains were obtained by mean of random\nwalks in continuum space. Two potential models were considered to represent\nshort range interactions between monomers. Various structural properties during\nthe collapse of the polymer were measured and different collapse pathways were\nobserved. For low temperatures, we have obtained a spontaneous collapse to\nhelical states."
    },
    {
        "anchor": "Phase separation around heated colloid in bulk and under confinement: We study the non-equilibrium coarsening dynamics of a binary liquid solvent\naround a colloidal particle in a presence of a time-dependent temperature\ngradient that emerges after temperature quench of a suitably coated colloid\nsurface. The solvent is maintained at its critical concentration and the\ncolloid is fixed in space. The coarsening patterns near the surface are shown\nto be strongly dependent on the colloid surface adsorption properties and on\nthe temperature evolution. The temperature gradient alters the morphology of a\nbinary solvent near the surface of a colloid as compared to the coarsening\nproceeding at constant temperature everywhere. We also present results for the\nevolution of coarsening in thin films with confining surfaces preferring one\nspecies of the binary liquid mixture over the other. Confinement leads to a\nfaster phase segregation process and formation of a bridge connecting the\ncolloid and both the confining walls.",
        "positive": "Minimal model for aeolian sand dunes: We present a minimal model for the formation and migration of aeolian sand\ndunes. It combines a perturbative description of the turbulent wind velocity\nfield above the dune with a continuum saltation model that allows for\nsaturation transients in the sand flux. The latter are shown to provide the\ncharacteristic length scale. The model can explain the origin of important\nfeatures of dunes, such as the formation of a slip face, the broken scale\ninvariance, and the existence of a minimum dune size. It also predicts the\nlongitudinal shape and aspect ratio of dunes and heaps, their migration\nvelocity and shape relaxation dynamics. Although the minimal model employs\nnon-local expressions for the wind shear stress as well as for the sand flux,\nit is simple enough to serve as a very efficient tool for analytical and\nnumerical investigations and to open up the way to simulations of large scale\ndesert topographies."
    },
    {
        "anchor": "Effective index of refraction, optical rotation, and circular dichroism\n  in isotropic chiral liquid crystals: This paper concerns optical properties of the isotropic phase above the\nisotropic-cholesteric transition and of the blue phase BP III. We introduce an\neffective index, which describes spatial dispersion effects such as optical\nrotation, circular dichroism, and the modification of the average index due to\nthe fluctuations. We derive the wavelength dependance of these spatial\ndispersion effects quite generally without relying on an expansion in powers of\nthe chirality and without assuming that the pitch of the cholesteric $P$ is\nmuch shorter than the wavelength of the light $\\lambda$, an approximation which\nhas been made in previous studies of this problem. The theoretical predictions\nare supported by comparing them with experimental spectra of the optical\nactivity in the BP III phase.",
        "positive": "Integral relations for the surface transfer coefficients: In this paper we derive relations between the local resistivities inside the\ninterfacial region and the overall resistances of the surface between two\nphases for a mixture. These resistivities are the coefficients in the\nforce-flux relations for the stationary heat and mass transfer through the\ninterface. We have shown that interfacial resistances depend among other things\non the enthalpy profile across the interface. Since this variation is\nsubstantial (the enthalpy of evaporation is one of the main differences between\nliquid and vapor phases) the interfacial resistivities are also substantial.\nParticularly, surface put up much more resistance to the heat and mass transfer\nthen the homogeneous phase. This is the case not only for the pure heat\nconduction and diffusion but also for the cross effects like thermal diffusion."
    },
    {
        "anchor": "Nature of Sub-diffusion Crossover in Molecular and Polymeric\n  Glass-Formers: A crossover from a non-Gaussian to Gaussian sub-diffusion has been observed\nubiquitously in various polymeric/molecular glass-formers. We have developed a\nframework which generalizes the fractional Brownian motion (fBm) model to\nincorporate non-Gaussian features by introducing a jump kernel. We illustrate\nthat the non-Gaussian fBm (nGfBm) model accurately characterizes the\nsub-diffusion crossover. From the solutions of the nGfBm model, we gain\ninsights into the nature of van-Hove self-correlation in non-Gaussian\nsubdiffusive regime, which are found to exhibit exponential tails, providing\nfirst such experimental evidence in molecular and polymeric glass-formers. The\nresults of the model are substantiated using incoherent quasielastic neutron\nscattering on glass-forming deep eutectic solvents.",
        "positive": "The Glass-like Structure of Globular Proteins and the Boson Peak: Vibrational spectra of proteins and topologically disordered solids display a\ncommon anomaly at low frequencies, known as Boson peak. We show that such\nfeature in globular proteins can be deciphered in terms of an energy landscape\npicture, as it is for glassy systems. Exploiting the tools of Euclidean random\nmatrix theory, we clarify the physical origin of such anomaly in terms of a\nmechanical instability of the system. As a natural explanation, we argue that\nsuch instability is relevant for proteins in order for their molecular\nfunctions to be optimally rooted in their structures."
    },
    {
        "anchor": "Preferential Root Tropism Induced by Structural Inhomogeneities in 2D\n  Wet Granular Media: We investigate certain aspects of the physical mechanisms of root growth in a\ngranular medium and how these roots adapt to changes in water distribution\ninduced by the presence of structural inhomogeneities in the form of solid\nintrusions. Physical intrusions such as a square rod added into the 2D granular\nmedium modify water distribution by maintaining robust capillary action,\npumping water from the more saturated areas at the bottom of the cell towards\nthe less saturated areas near the top of the cell while the rest of the medium\nis slowly devoid of water via evaporation. This water redistribution induces\n`preferential tropism' of roots, guiding the roots and permitting them to grow\ndeeper into more saturated regions in the soil. This further allows more\nefficient access to available water in the deeper sections of the medium\nthereby resulting to increased plant lifetime",
        "positive": "Relaxation time of a polymer glass stretched at very large strains: The polymer relaxation dynamic of a sample, stretched up to the stress\nhardening regime, is measured, at room temperature, as a function of the strain\n$\\lambda$ for a wide range of the strain rate $\\dot\\gamma$, by an original\ndielectric spectroscopy set up. The mechanical stress modies the shape of the\ndielectric spectra mainly because it affects the dominant polymer relaxation\ntime $\\tau$, which depends on $\\lambda$ and is a decreasing function of\n$\\dot\\gamma$. The fastest dynamics is not reached at yield but in the softening\nregime. The dynamics slows down during the hardening, with a progressive\nincrease of $\\tau$. A small inuence of $\\dot\\gamma$ and $\\lambda$ on the\ndielectric strength cannot be excluded."
    },
    {
        "anchor": "Thermodynamic restrictions on evolutionary optimization of transcription\n  factor proteins: Conformational fluctuations are believed to play an important role in the\nprocess by which transcription factor proteins locate and bind their target\nsite on the genome of a bacterium. Using a simple model, we show that the\nbinding time can be minimized, under selective pressure, by adjusting the\nspectrum of conformational states so that the fraction of time spent in more\nmobile conformations is matched with the target recognition rate. The\nassociated optimal binding time is then within an order of magnitude of the\nlimiting binding time imposed by thermodynamics, corresponding to an idealized\nprotein with instant target recognition. Numerical estimates suggest that\ntypical bacteria operate in this regime of optimized conformational\nfluctuations.",
        "positive": "Boundary Singularities Produced by the Motion of Soap Films: Recent work has shown that a M\\\"obius strip soap film rendered unstable by\ndeforming its frame changes topology to that of a disk through a\n'neck-pinching' boundary singularity. This behavior is unlike that of the\ncatenoid, which transitions to two disks through a bulk singularity. It is not\nyet understood whether the type of singularity is generally a consequence of\nthe surface topology, nor how this dependence could arise from an equation of\nmotion for the surface. To address these questions we investigate\nexperimentally, computationally, and theoretically the route to singularities\nof soap films with different topologies, including a family of punctured Klein\nbottles. We show that the location of singularities (bulk or boundary) may\ndepend on the path of the boundary deformation. In the unstable regime the\ndriving force for soap-film motion is the mean curvature. Thus, the narrowest\npart of the neck, associated with the shortest nontrivial closed geodesic of\nthe surface, has the highest curvature and is the fastest-moving. Just before\nonset of the instability there exists on the stable surface a shortest closed\ngeodesic, which is the initial condition for evolution of the neck's geodesics,\nall of which have the same topological relationship to the frame. We make the\nplausible conjectures that if the initial geodesic is linked to the boundary\nthen the singularity will occur at the boundary, whereas if the two are\nunlinked initially then the singularity will occur in the bulk. Numerical study\nof mean curvature flows and experiments support these conjectures."
    },
    {
        "anchor": "Induced Orientational Effects in Relaxation of Polymer Melts: We study stress relaxation in bi-disperse entangled polymer solutions.\nShorter chains embedded in a majority of longer ones are known to be oriented\nby coupling to them. We analyze the mechanism for this both by computer\nsimulation and theoretically. We show that the results can be understood in\nterms of stress fluctuations in a polymer melt and chain screening. Stress\nfluctuations are frozen on the relaxation time of the longer chains, and these\nwill induce strong orientational couplings in the shorter chains.",
        "positive": "Memory-induced motion reversal in Brownian liquids: We study the Brownian dynamics of hard spheres under spatially inhomogeneous\nshear, using event-driven Brownian dynamics simulations and power functional\ntheory. We examine density and current profiles both for steady states and for\nthe transient dynamics after switching on and switching off an external square\nwave shear force field. We find that a dense hard sphere fluid (volume fraction\n$\\approx$0.35) undergoes global motion reversal after switching off the shear\nforce field. We use power functional theory with a spatially nonlocal memory\nkernel to describe the superadiabatic force contributions and obtain good\nquantitative agreement of the theoretical results with simulation data. The\ntheory provides an explanation for the motion reversal: Internal superadiabatic\nnonequilibrium forces that oppose the externally driven current arise due to\nmemory after switching off. The effect is genuinely viscoelastic: in steady\nstate, viscous forces oppose the current, but they elastically generate an\nopposing current after switch-off."
    },
    {
        "anchor": "Holographic assembly of quasicrystalline photonic heterostructures: Quasicrystals have a higher degree of rotational and point-reflection\nsymmetry than conventional crystals. As a result, quasicrystalline\nheterostructures fabricated from dielectric materials with micrometer-scale\nfeatures exhibit interesting and useful optical properties including large\nphotonic bandgaps in two-dimensional systems. We demonstrate the holographic\nassembly of two-dimensional and three-dimensional dielectric quasicrystalline\nheterostructures, including structures with specifically engineered defects.\nThe highly uniform quasiperiodic arrays of optical traps used in this process\nalso provide model aperiodic potential energy landscapes for fundamental\nstudies of transport and phase transitions in soft condensed matter systems.",
        "positive": "Forced Rayleigh Scattering Studies of Tracer Diffusion in a Nematic\n  Liquid Crystal: The Relevance of Complementary Gratings: We have employed forced Rayleigh scattering (FRS) to study the diffusion of\nan azo tracer molecule (methyl red) through a nematic liquid crystal (5CB).\nThis system was first investigated in an important study by Hara et al. (Japan.\nJ. Appl. Phys. 23, 1420 [1984]). Since that time, it has become clear that the\npresence of complementary ground-state and photoproduct FRS gratings can result\nin nonexponential profiles, and that complementary-grating effects are\nsignificant even when \"minor\" deviations from exponential decay are observed.\nWe have investigated the methyl red/5CB system in order to evaluate the\npossible effects of complementary gratings. In the isotropic phase, we find\nthat the presence of complementary gratings results in a nonmonotonic FRS\nsignal, which significantly changes the values inferred for the isotropic\ndiffusion coefficients. As a result, the previously reported discontinuity at\nthe nematic/isotropic transition temperature (TNI) is not present in the new\ndata. On the other hand, in the nematic phase, the new experiments largely\nconfirm the previous observations of single-exponential FRS decay and the\nnon-Arrhenius temperature dependence of the nematic diffusion coefficients\nclose to TNI. Finally, we have also observed that the decrease in the diffusion\nanisotropy with increasing temperature can be correlated with the 5CB nematic\norder parameter S(T) over the full nematic temperature range."
    },
    {
        "anchor": "Morphologies of three-dimensional shear bands in granular media: We present numerical results on spontaneous symmetry breaking strain\nlocalization in axisymmetric triaxial shear tests of granular materials. We\nsimulated shear band formation using three-dimensional Distinct Element Method\nwith spherical particles. We demonstrate that the local shear intensity, the\nangular velocity of the grains, the coordination number, and the local void\nratio are correlated and any of them can be used to identify shear bands,\nhowever the latter two are less sensitive. The calculated shear band\nmorphologies are in good agreement with those found experimentally. We show\nthat boundary conditions play an important role. We discuss the formation\nmechanism of shear bands in the light of our observations and compare the\nresults with experiments. At large strains, with enforced symmetry, we found\nstrain hardening.",
        "positive": "Structure and organization in inclusion-containing bilayer membranes: Membrane organization is essential for cellular functions such as signal\ntransduction and membrane trafficking. A major challenge is to understand the\nlateral heterogeneous structures in membranes and membrane fluidity in the\npresence of inclusions. Based on a considerable amount of experimental evidence\nfor lateral organization of lipid membranes which share astonishingly similar\nfeatures in the presence of different inclusions, we first present a general\nmodel system of bilayer membranes embedded by nanosized inclusions, and explain\nexperimental findings. Here, the hydrophobic inclusions are simple models of\nintrinsic membrane proteins, cholesterol embedded in the membrane, hydrophobic\ndrugs, or other nanoparticles for bio-medical applications. It is found that\nlipid/inclusion-rich raft domains are formed at moderate inclusion\nconcentrations, and disappear with the increase of inclusions. At high\ninclusion content, chaining of inclusions occurs due to the effective\nattraction between inclusions mediated by lipids. Meanwhile, increasing\ninclusions can also cause thickening of the membrane, and the distribution of\ninclusions undergoes a layering transition from one-layer located in the\nbilayer midplane to two-layer structure arranged into the two leaflets of a\nbilayer. Our theoretical predictions address the complex interactions between\nmembranes and inclusions, suggesting a unifying mechanism which reflects the\ncompetition between the conformational entropy of lipids favoring the formation\nof lipid-rich rafts and the steric repulsion of inclusions leading to the\nuniform dispersion."
    },
    {
        "anchor": "The contribution of electrostatic interactions to the collapse of\n  oligoglycine in water: Protein solubility and conformational stability are a result of a balance of\ninteractions both within a protein and between protein and solvent. The\nelectrostatic solvation free energy of oligoglycines, models for the peptide\nbackbone, becomes more favorable with an increasing length, yet longer peptides\ncollapse due to the formation of favorable intrapeptide interactions between CO\ndipoles, in some cases without hydrogen bonds. The strongly repulsive solvent\ncavity formation is balanced by van der Waals attractions and electrostatic\ncontributions. In order to investigate the competition between solvent\nexclusion and charge interactions we simulate the collapse of a long\noligoglycine comprised of 15 residues while scaling the charges on the peptide\nfrom zero to fully charged. We examine the effect this has on the\nconformational properties of the peptide. We also describe the approximate\nthermodynamic changes that occur during the scaling both in terms of\nintrapeptide potentials and peptide-water potentials, and estimate the\nelectrostatic solvation free energy of the system.",
        "positive": "Ion Conductivity and Correlations in Model Salt-Doped Polymers: Effects\n  of Interaction Strength and Concentration: Correlated anion and cation motion can significantly reduce the overall ion\nconductivity in electrolytes versus the ideal conductivity calculated based on\nthe diffusion constants alone. Using coarse-grained molecular dynamics\nsimulations, we calculate conductivity and the degree of uncorrelated ion\nmotion in salt-doped homopolymers and block copolymers as a function of\nconcentration and interaction strengths. Calculating conductivity from ion\nmobility under an applied electric field increases accuracy versus the typical\nuse of fluctuation dissipation relationships in equilibrium simulations. In\ntypical electrolytes, correlation in cation-anion motion is often expected to\nbe reduced at low ion concentrations. However, for these polymer electrolytes\nwith strong ion-polymer and ion-ion interactions, we find correlations are\nincreased at lower concentrations when other variables are held constant. We\nshow this phenomenon is related to the slower ion cluster relaxation rate at\nlow concentrations rather than the static spatial state of ion aggregation or\nthe fraction of free ions."
    },
    {
        "anchor": "Self-induced hydrodynamic coil-stretch transition of active polymers: We analyze the conformational dynamics and statistical properties of an\nactive polymer model. The polymer is described as a freely-jointed bead-rod\nchain subject to stochastic active force dipoles that act on the suspending\nsolvent where they drive long-ranged fluid flows. Using Langevin simulations of\nisolated chains in unconfined domains, we show how the coupling of active flows\nwith polymer conformations leads to emergent dynamics. Systems with contractile\ndipoles behave similarly to passive Brownian chains with enhanced fluctuations\ndue to dipolar flows. In systems with extensile dipoles, however, our\nsimulations uncover an active coil-stretch transition whereby the polymer\nspontaneously unfolds and stretches out in its own self-induced hydrodynamic\nflow, and we characterize this transition in terms of a dimensionless activity\nparameter comparing active dipolar forces to thermal fluctuations. We discuss\nour findings in the context of the classic coil-stretch transition of passive\npolymers in extensional flows, and complement our simulations with a simple\nkinetic model for an active trimer.",
        "positive": "Generating ring currents, solitons, and svortices by stirring a\n  Bose-Einstein condensate in a toroidal trap: We propose a simple stirring experiment to generate quantized ring currents\nand solitary excitations in Bose-Einstein condensates in a toroidal trap\ngeometry. Simulations of the 3D Gross-Pitaevskii equation show that pure ring\ncurrent states can be generated efficiently by adiabatic manipulation of the\ncondensate, which can be realized on experimental time scales. This is\nillustrated by simulated generation of a ring current with winding number two.\nWhile solitons can be generated in quasi-1D tori, we show the even more robust\ngeneration of hybrid, solitonic vortices (svortices) in a regime of wider\nconfinement. Svortices are vortices confined to essentially one-dimensional\ndynamics, which obey a similar phase-offset--velocity relationship as solitons.\nMarking the transition between solitons and vortices, svortices are a distinct\nclass of symmetry-breaking stationary and uniformly rotating excited solutions\nof the 2D and 3D Gross-Pitaevskii equation in a toroidal trapping potential.\nSvortices should be observable in dilute-gas experiments."
    },
    {
        "anchor": "Assembling of three-dimensional crystals by large nonequilibrium\n  depletion force: We propose and demonstrate a method to achieve large effective Soret\ncoefficient in colloids by suitably mixing two different particles, e.g.,\nsilica beads and Fe3O4 nanoparticles. It is shown that the thermophoretic\nmotion of Fe3O4 nanoparticles out of the heating region results in a large\nnonequlibrium depletion force for silica beads. Consequently, silica beads are\ndriven quickly to the heating region, forming a three-dimensional crystal with\nfew defects and dislocations. The binding of silica beads is so tight that a\ncolloidal photonic crystal can be achieved after the complete evaporation of\nsolvent, water. Thus, for fabrication of defect free colloidal PCs, periodic\nstructures for molecular sieves, among others, the proposed technique could be\na low cost alternative. In addition as we use biocompatible materials, this\ntechnique could be a tool for biophysics studies where the potential of large\neffective Soret coefficient could be useful.",
        "positive": "Modelling fluids and crystals using a two-component modified phase field\n  crystal model: A modified phase field crystal model in which the free energy may be\nminimised by an order parameter profile having isolated bumps is investigated.\nThe phase diagram is calculated in one and two dimensions and we locate the\nregions where modulated and uniform phases are formed and also regions where\nlocalised states are formed. We investigate the effectiveness of the phase\nfield crystal model for describing fluids and crystals with defects. We further\nconsider a two component model and elucidate how the structure transforms from\nhexagonal crystalline ordering to square ordering as the concentration changes.\nOur conclusion contains a discussion of possible interpretations of the order\nparameter field."
    },
    {
        "anchor": "Mechanical equilibrium of aggregates of dielectric spheres: Industrial as well as natural aggregation of fine particles is believed to be\nassociated with electrostatics. Yet like charges repel, so it is unclear how\nsimilarly treated particles aggregate. To resolve this apparent contradiction,\nwe analyze conditions necessary to hold aggregates together with electrostatic\nforces. We find that aggregates of particles charged with the same sign can be\nheld together due to dielectric polarization, we evaluate the effect of\naggregate size, and we briefly summarize consequences for practical\naggregation.",
        "positive": "Non-affine displacements in flexible polymer networks: The validity of the affine assumption in model flexible polymer networks is\nexplored. To this end, the displacements of fluorescent tracer beads embedded\nin polyacrylamide gels are quantified by confocal microscopy under shear\ndeformation, and the deviations of these displacements from affine responses\nare recorded. Non-affinity within the gels is quantified as a function of\npolymer chain density and cross-link concentration. Observations are in\nqualitative agreement with current theories of polymer network non-affinity.\nThe measured degree of non-affinity in the polyacrylamide gels suggests the\npresence of structural inhomogeneities which likely result from heterogeneous\nreaction kinetics during gel preparation. In addition, the macroscopic\nelasticity of the polyacrylamide gels is confirmed to behave in accordance with\nstandard models of flexible polymer network elasticity."
    },
    {
        "anchor": "Pressure in an exactly solvable model of active fluid: We consider the pressure in the steady-state regime of three stochastic\nmodels characterized by self-propulsion and persistent motion and widely\nemployed to describe the behavior of active particles, namely the Active\nBrownian particle (ABP) model, the Gaussian colored noise (GCN) model and the\nunified colored noise model (UCNA). Whereas in the limit of short but finite\npersistence time the pressure in the UCNA model can be obtained by different\nmethods which have an analog in equilibrium systems, in the remaining two\nmodels only the virial route is, in general, possible.\n  According to this method, notwithstanding each model obeys its own specific\nmicroscopic law of evolution, the pressure displays a certain universal\nbehavior. For generic interparticle and confining potentials, we derive a\nformula which establishes a correspondence between the GCN and the UCNA\npressures. In order to provide explicit formulas and examples, we specialize\nthe discussion to the case of an assembly of elastic dumbbells confined to a\nparabolic well. By employing the UCNA we find that, for this model, the\npressure determined by the thermodynamic method coincides with the pressures\nobtained by the virial and mechanical methods. The three methods when applied\nto the GCN give a pressure identical to that obtained via the UCNA. Finally, we\nfind that the ABP virial pressure exactly agrees with the UCNA and GCN result.",
        "positive": "Exact equilibrium properties of square-well and square-shoulder disks in\n  single-file confinement: This study investigates the (longitudinal) thermodynamic and structural\ncharacteristics of single-file confined square-well and square-shoulder disks\nby employing a mapping technique that transforms the original system into a\none-dimensional polydisperse mixture of nonadditive rods. Leveraging standard\nstatistical-mechanical techniques, exact results are derived for key\nproperties, including the equation of state, internal energy, radial\ndistribution function, and structure factor. The asymptotic behavior of the\nradial distribution function is explored, revealing structural changes in the\nspatial correlations. Additionally, exact analytical expressions for the second\nvirial coefficient are presented. Comparisons with Monte Carlo simulations\ndemonstrate an excellent agreement with theory."
    },
    {
        "anchor": "Anomalous Stress Fluctuations in Athermal Two Dimensional Amorphous\n  Solids: We numerically study the local stress distribution within athermal,\nisotropically stressed, mechanically stable, packings of bidisperse\nfrictionless disks above the jamming transition in two dimensions. Considering\nthe Fourier transform of the local stress, we find evidence for algebraically\nincreasing fluctuations in both isotropic and anisotropic components of the\nstress tensor at small wavenumbers, contrary to recent theoretical predictions.\nSuch increasing fluctuations imply a lack of self-averaging of the stress on\nlarge length scales. The crossover to these increasing fluctuations defines a\nlength scale $\\ell_0$, however it appears that $\\ell_0$ does not vary much with\npacking fraction $\\phi$, nor does $\\ell_0$ seem to be diverging as $\\phi$\napproaches the jamming $\\phi_J$. We also find similar large length scale\nfluctuations of stress in the inherent states of a quenched Lennard-Jones\nliquid, leading us to speculate that such fluctuations may be a general\nproperty of amorphous solids in two dimensions.",
        "positive": "Viscous fingering patterns in ferrofluids: Viscous fingering occurs in the flow of two immiscible, viscous fluids\nbetween the plates of a Hele-Shaw cell. Due to pressure gradients or gravity,\nthe initially planar interface separating the two fluids undergoes a\nSaffman-Taylor instability and develops finger-like structures. When one of the\nfluids is a ferrofluid and a perpendicular magnetic field is applied, the\nlabyrinthine instability supplements the usual viscous fingering instability,\nresulting in visually striking, complex patterns. We consider this problem in a\nrectangular flow geometry using a perturbative mode-coupling analysis. We\ndeduce two general results: viscosity contrast between the fluids drives\ninterface asymmetry, with no contribution from magnetic forces; magnetic\nrepulsion within the ferrofluid generates finger tip-splitting, which is absent\nin the rectangular geometry for ordinary fluids."
    },
    {
        "anchor": "High-speed photoelastic tomography for axisymmetric stress fields in a\n  soft material: temporal evolution of all stress components: This study presents a novel approach for reconstructing all stress components\nof the dynamic axisymmetric fields of a soft material using photoelastic\ntomography (PT) and a high-speed polarization camera. This study focuses on\nstatic and dynamic Hertzian contact as an example of transient stress field\nreconstructions. For the static Hertzian contact (a solid sphere pressed\nagainst a gel block), all stress components in the urethane gel, which has an\nelastic modulus of 47.4 kPa, were reconstructed by PT using the measured\nphotoelastic parameters. The results were compared with theoretical solutions\nand showed good agreement. For the dynamic Hertzian contact (a sphere impacting\ngel), a high-speed polarization camera was used to reconstruct the transient\nstress field within the gel. PT was used to quantitatively measure the shear\nand axial stress waves and showed different propagation speeds on the\nsubstrate. The technique allowed the simultaneous measurement of stress fields\nranging from $O(10^{-1})$ to $O(10^1)$ kPa during large deformations,\ndemonstrating its accuracy in capturing rapidly changing stress tensor\ncomponents in dynamic scenarios. The scaling laws of the calculated impact\nforce agreed with theoretical predictions, validating the accuracy of PT for\nmeasuring dynamic axisymmetric stress fields in soft materials.",
        "positive": "Emergence of zero modes in disordered solids under periodic tiling: In computational models of particle packings with periodic boundary\nconditions, it is assumed that the packing is attached to exact copies of\nitself in all possible directions. The periodicity of the boundary then\nrequires that all of the particles' images move together. An infinitely\nrepeated structure, on the other hand, does not necessarily have this\nconstraint. As a consequence, a jammed packing (or a rigid elastic network)\nunder periodic boundary conditions may have a corresponding infinitely repeated\nlattice representation that is not rigid or indeed may not even be at a local\nenergy minimum. In this manuscript, we prove this claim and discuss ways in\nwhich periodic boundary conditions succeed to capture the physics of repeated\nstructures and where they fall short."
    },
    {
        "anchor": "Modeling dependence of creep recovery behavior on relaxation time\n  distribution of ageing colloidal suspensions: A scaling model is developed to correlate relaxation time distribution of\nsoft glassy materials to ultimate recovery. We propose that in the limit of\ncreep-recovery time smaller than age, time translational invariance can be\napplied to ageing soft materials. In such limit, multimode linear viscoelastic\nmodel with Spriggs relaxation spectrum predicts enhancement in the ultimate\nrecovery with broadening of the relaxation time distribution. We analyze these\nresults in the context of creep-recovery behavior of aqueous suspension of\nlaponite with varying concentration of salt.",
        "positive": "Hydrodynamic Coupling of Two Brownian Spheres to a Planar Surface: We describe direct imaging measurements of the collective and relative\ndiffusion of two colloidal spheres near a flat plate. The bounding surface\nmodifies the spheres' dynamics, even at separations of tens of radii. This\nbehavior is captured by a stokeslet analysis of fluid flow driven by the\nspheres' and wall's no-slip boundary conditions. In particular, this analysis\nreveals surprising asymmetry in the normal modes for pair diffusion near a flat\nsurface."
    },
    {
        "anchor": "Active microrheology in corrugated channels: We analyze the dynamics of a tracer particle embedded in a bath of hard\nspheres confined in a channel of varying section. By means of Brownian dynamics\nsimulations we apply a constant force on the tracer particle and discuss the\ndependence of its mobility on the relative magnitude of the external force with\nrespect to the entropic force induced by the confinement. A simple theoretical\none-dimensional model is also derived, where the contribution from\nparticle-particle and particle-wall interactions is taken from simulations with\nno external force. Our results show that the mobility of the tracer is strongly\naffected by the confinement. The tracer velocity in the force direction has a\nmaximum close to the neck of the channel, in agreement with the theory for\nsmall forces. Upon increasing the external force, the tracer is effectively\nconfined to the central part of the channel and the velocity modulation\ndecreases, what cannot be reproduced by the theory. This deviation marks the\nregime of validity of linear response. Surprisingly, when the channel section\nis not constant the effective friction coefficient is reduced as compared to\nthe case of a plane channel. The transversal velocity, which cannot be studied\nwith our model, follows the qualitatively the derivative of the channel\nsection, in agreement previous theoretical calculations for the tracer\ndiffusivity in equilibrium.",
        "positive": "Inertia and universality of avalanche statistics: The case of slowly\n  deformed amorphous solids: By means of a finite elements technique we solve numerically the dynamics of\nan amorphous solid under deformation in the quasistatic driving limit. We study\nthe noise statistics of the stress-strain signal in the steady state plastic\nflow, focusing on systems with low internal dissipation. We analyze the\ndistributions of avalanche sizes and durations and the density of shear\ntransformations when varying the damping strength. In contrast to avalanches in\nthe overdamped case, dominated by the yielding point universal exponents,\ninertial avalanches are controlled by a non-universal damping dependent\nfeedback mechanism; eventually turning negligible the role of correlations.\nStill, some general properties of avalanches persist and new scaling relations\ncan be proposed."
    },
    {
        "anchor": "Phonon Dispersion and Elastic Moduli of Two-Dimensional Disordered\n  Colloidal Packings of Soft Particles with Frictional Interactions: Particle tracking and displacement covariance matrix techniques are employed\nto investigate the phonon dispersion relations of two-dimensional colloidal\nglasses composed of soft, thermoresponsive microgel particles whose\ntemperature-sensitive size permits \\textit{in situ} variation of particle\npacking fraction. Bulk, $B$, and shear, $G$, moduli of the colloidal glasses\nare extracted from the dispersion relations as a function of packing fraction,\nand variation of the ratio $G/B$ with packing fraction is found to agree\nquantitatively with predictions for jammed packings of frictional soft\nparticles. In addition, $G$ and $B$ individually agree with numerical\npredictions for frictional particles. This remarkable level of agreement\nenabled us to extract an energy scale for the inter-particle interaction from\nthe individual elastic constants and to derive an approximate estimate for the\ninter-particle friction coefficient.",
        "positive": "Coarse-Grained Counterions in the Strong Coupling Limit: Recent Monte Carlo simulations (A. G. Moreira and R. R. Netz: Eur. Phys. J. E\n{\\bf 8} (2002) 33) in the strong Coulomb coupling regime suggest strange\ncounterion electrostatics unlike the Poisson-Boltzmann picture: when\ncounterion-counterion repulsive interactions are much larger than\ncounterion--macroion attraction, the coarse-grained counterion distribution\naround a macroion is determined only by the latter, and the former is\nirrelevant. Here, we offer an explanation for the apparently paradoxical\nelectrostatics by mathematically manipulating the strong coupling limit."
    },
    {
        "anchor": "Morphological analysis of chiral rod clusters from a coarse-grained\n  single-site chiral potential: We present a coarse-grained single-site potential for simulating chiral\ninteractions, with adjustable strength, handedness, and preferred twist angle.\nAs an application, we perform basin-hopping global optimisation to predict the\nfavoured geometries for clusters of chiral rods. The morphology phase diagram\nbased upon these predictions has four distinct families, including previously\nreported structures for potentials that introduce chirality based on shape,\nsuch as membranes and helices. The transition between these two configurations\nreproduces some key features of experimental results for {\\it{fd}}\nbacteriophage. The potential is computationally inexpensive, intuitive, and\nversatile; we expect it will be useful for large scale simulations of chiral\nmolecules. For chiral particles confined in a cylindrical container we\nreproduce the behaviour observed for fusilli pasta in a jar. Hence this\nchiropole potential has the capability to provide insight into structures on\nboth macroscopic and molecular length scales.",
        "positive": "Linear response and stability of ordered phases of diblock copolymer\n  melts: An efficient pseudo-spectral numerical method is introduced for calculating a\nself-consistent field (SCF) approximation for the linear susceptibility of\nordered phases in block copolymer melts (sometimes referred to as the random\nphase approximation). Our method is significantly more efficient than that used\nin the first calculations of this quantity by Shi, Laradji and coworkers,\nallowing for the study of more strongly segregated structures. We have\nre-examined the stability of several phases of diblock copolymer melts, and\nfind that some conclusions of Laradji et al. regarding the stability of the\nGyroid phase were the result of insufficient spatial resolution. We find that\nan epitaxial (k=0) instability of the Gyroid phase with respect to the\nhexagonal phase that was considered previously by Matsen competes extremely\nclosely with an instability that occurs at a nonzero crystal wavevector k."
    },
    {
        "anchor": "Molecular chains under tension: Thermal and mechanical activation of\n  statistically interacting extension and contraction particles: This work introduces a methodology for the statistical mechanical analysis of\npolymeric chains under tension controlled by optical or magnetic tweezers at\nthermal equilibrium with an embedding fluid medium. The response of single\nbonds between monomers or of entire groups of monomers to tension is governed\nby the activation of statistically interacting particles representing quanta of\nextension or contraction. This method of analysis is capable of describing\nthermal unbending of the freely jointed or wormlike chain kind, linear or\nnonlinear contour elasticity, and structural transformations including effects\nof cooperativity. The versatility of this approach is demonstrated in an\napplication to double-stranded DNA undergoing torsionally unconstrained\nstretching across three regimes of mechanical response including an\noverstretching transition. The three-regime force-extension characteristic,\nderived from a single free-energy expression, accurately matches empirical\nevidence.",
        "positive": "Rigid flocks, undulatory gaits, and chiral foldamers from chemical\n  self-interaction in a freely-jointed active colloidal chain: Active matter systems - such as a collection of active colloidal particles -\noperate far from equilibrium with complex inter-particle interactions that\ngovern their collective dynamics. Predicting the collective dynamics of such\nsystems may aid the design of self-shaping structures comprised of active\ncolloidal units with a prescribed dynamical function. Here, using simulations\nand theory, we study the collective dynamics of a chain consisting of active\nBrownian particles with internal interactions via trail-mediated chemicals,\nconnected by harmonic springs in two dimensions to obtain design principles for\nactive colloidal molecules. We show that two-dimensional confinement and\nchemo-repulsive interactions between the freely-jointed particles lead to an\nemergent rigidity of the chain in the steady-state dynamics. In the\nchemo-attractive regime, the chain collapses into crystals that abruptly halt\ntheir motion. Further, in a chain consisting of a binary mixture of monomers,\nwe show that non-reciprocal chemical affinities between distinct species give\nrise to novel phenomena, such as chiral molecules with tunable dynamics,\nsustained undulatory gaits and reversal of the direction of motion. Our results\nsuggest a novel interpretation of the role of trail-mediated interactions, in\naddition to providing active self-assembly principles."
    },
    {
        "anchor": "Pressure-energy correlations in liquids. I. Results from computer\n  simulations: We show that a number of model liquids at fixed volume exhibit strong\ncorrelations between equilibrium fluctuations of the configurational parts of\n(instantaneous) pressure and energy. We present detailed results for thirteen\nsystems, showing in which systems these correlations are significant. These\ninclude Lennard-Jones liquids (both single- and two-component) and several\nother simple liquids, but not hydrogen-bonding liquids like methanol and water,\nnor the Dzugutov liquid which has significant contributions to pressure at the\nsecond nearest neighbor distance. The pressure-energy correlations, which for\nthe Lennard-Jones case are shown to also be present in the crystal and glass\nphases, reflect an effective inverse power-law potential dominating\nfluctuations, even at zero and slightly negative pressure. An exception to the\ninverse-power law explanation is a liquid with hard-sphere repulsion and a\nsquare-well attractive part, where a strong correlation is observed, but only\nafter time-averaging. The companion paper [arXiv:0807.0551] gives a thorough\nanalysis of the correlations, with a focus on the Lennard-Jones liquid, and a\ndiscussion of some experimental and theoretical consequences.",
        "positive": "Hidden Markov modeling of single particle diffusion with stochastic\n  tethering: The statistics of the diffusive motion of particles often serve as an\nexperimental proxy for their interaction with the environment. However,\ninferring the physical properties from the observed trajectories is\nchallenging. Inspired by a recent experiment, here we analyze the problem of\nparticles undergoing two-dimensional Brownian motion with transient tethering\nto the surface. We model the problem as a Hidden Markov Model where the\nphysical position is observed, and the tethering state is hidden. We develop an\nalternating maximization algorithm to infer the hidden state of the particle\nand estimate the physical parameters of the system. The crux of our method is a\nsaddle-point-like approximation, which involves finding the most likely\nsequence of hidden states and estimating the physical parameters from it.\nExtensive numerical tests demonstrate that our algorithm reliably finds the\nmodel parameters, and is insensitive to the initial guess. We discuss the\ndifferent regimes of physical parameters and the algorithm's performance in\nthese regimes. We also provide a ready-to-use open source implementation of our\nalgorithm."
    },
    {
        "anchor": "Switching dynamics in cholesteric liquid crystal emulsions: In this work we numerically study the switching dynamics of a 2D cholesteric\nemulsion droplet immersed in an isotropic fluid under an electric field, which\nis either uniform or rotating with constant speed. The overall dynamics depend\nstrongly on the magnitude and on the direction (with respect to the cholesteric\naxis) of the applied field, on the anchoring of the director at the droplet\nsurface and on the elasticity. If the surface anchoring is homeotropic and a\nuniform field is parallel to the cholesteric axis, the director undergoes deep\nelastic deformations and the droplet typically gets stuck into metastable\nstates which are rich in topological defects. When the surface anchoring is\ntangential, the effects due to the electric field are overall less dramatic, as\na small number of topological defects form at equilibrium. The application of\nthe field perpendicular to the cholesteric axis usually has negligible effects\non the defect dynamics. The presence of a rotating electric field of varying\nfrequency fosters the rotation of the defects and of the droplet as well,\ntypically at lower speed than that of the field, due to the inertia of the\nliquid crystal. If the surface anchoring is homeotropic a periodic motion is\nfound. Our results represent a first step to understand the dynamical response\nof a cholesteric droplet under an electric field and its possible application\nin designing novel liquid crystal-based devices.",
        "positive": "Nucleation and Bulk Crystallization in Binary Phase Field Theory: We present a phase field theory for binary crystal nucleation. In the\none-component limit, quantitative agreement is achieved with computer\nsimulations (Lennard-Jones system) and experiments (ice-water system) using\nmodel parameters evaluated from the free energy and thickness of the interface.\nThe critical undercoolings predicted for Cu-Ni alloys accord with the\nmeasurements, and indicate homogeneous nucleation. The Kolmogorov exponents\ndeduced for dendritic solidification and for \"soft-impingement\" of particles\nvia diffusion fields are consistent with experiment."
    },
    {
        "anchor": "Elastic continuum theory: Fully understanding of the twist-bend nematic\n  phases: The twist-bend nematic phase, $N_{\\rm TB}$, may be viewed as a heliconical\nmolecular arrangement in which the director $\\bf n$ precesses uniformly about\nan extra director field, $\\bf t$. It corresponds to a nematic ground state\nexhibiting nanoscale periodic modulation. To demonstrate the stability of this\nphase from the elastic point of view, a natural extension of the Frank elastic\nenergy density is proposed. The elastic energy density is built in terms of the\nelements of symmetry of the new phase in which intervene the components of\nthese director fields together with the usual Cartesian tensors. It is shown\nthat the ground state corresponds to a deformed state for which $K_{22} >\nK_{33}$. When the elastic free energy is interpreted in analogy with the Landau\ntheory, it is demonstrated the existence of a second order phase transition\nbetween the usual and the twist-bend nematic phase, driven by a new elastic\nparameter playing a role similar to the one of the main dielectric anisotropy\nof classical nematics and being closely related to the bulk compression modulus\nrepresenting the pseudo-layers of twist-bend nematic phases. A phase transition\nand the value of the nanoscale pitch are predicted in accordance to\nexperimental results.",
        "positive": "Coarsening Dynamics of Biaxial Nematic Liquid Crystals: We study the coarsening dynamics of two and three dimensional biaxial nematic\nliquid crystals, using Langevin dynamics. Unlike previous work, we use a model\nwith no a priori relationship among the three elastic constants associated with\ndirector deformations. We find a rich variety of coarsening behavior, including\nthe simulataneous decay of nearly equal populations of the three classes of\nhalf-integer disclination lines. The behavior we observed can be understood on\nthe basis of the relative values of the elastic constants and the resulting\ndecay channels of the defects."
    },
    {
        "anchor": "Universal deformation of soft substrates near a contact line and the\n  direct measurement of solid surface stresses: Droplets deform soft substrates near their contact lines. Using confocal\nmicroscopy, we measure the deformation of silicone gel substrates due to\nglycerol and fluorinated-oil droplets for a range of droplet radii and\nsubstrate thicknesses. For all droplets, the substrate deformation takes a\nuniversal shape close to the contact line that depends on liquid composition,\nbut is independent of droplet size and substrate thickness. This shape is\ndetermined by a balance of interfacial tensions at the contact line and\nprovides a novel method for direct determination of the surface stresses of\nsoft substrates. Moreover, we measure the change in contact angle with droplet\nradius and show that Young's law fails for small droplets when their radii\napproach an elastocapillary length scale. For larger droplets the macroscopic\ncontact angle is constant, consistent with Young's law.",
        "positive": "Oiling-out Crystallization of Beta-Alanine onSolid Surfaces Controlled\n  by Solvent Exchange: Droplet formation in oiling-out crystallization has important implication for\nseparation and purification of pharmaceutical active ingredients by using an\nantisolvent. In this work, we report the crystallization processes of\noiling-out droplets on surfaces during solvent exchange. Our model ternary\nsolution is beta-alanine dissolved in isopropanol and water mixture. As the\nantisolvent isopropanol displaced the alanine solution pre-filled in a\nmicrochamber, liquid-liquid phase separation occurred at the mixing front. The\nalanine-rich subphase formed surface microdroplets that subsequently\ncrystallized with progression of solvent exchange. We find that the flow rates\nhave significant influence on the droplet size, crystallization process, and\ngrowth rate, and final morphology of the crystals. At fast flow rates the\ndroplets solidified rapidly and formed spherical-cap structures resembling the\nshape of droplets, in contrast to crystal microdomains or thin films formed at\nslow flow rates. On a highly hydrophilic surface, the crystals formed thin film\nwithout droplets formed on the surface. We further demonstrated that by the\nsolvent exchange crystals can be formed by using a stock solution with a very\nlow concentration of the precursor, and the as-prepared crystals can be used as\nseeds to trigger crystallization in bulk solution. Our results suggest that the\nsolvent exchange has the potential to be an effective approach for controlling\noiling-out crystallization, which can be applied in wide areas, such as\nseparation and purification of many food, medical, and therapeutic ingredients."
    },
    {
        "anchor": "Universal and non-universal features in coarse-grained models of flow in\n  disordered solids: We study the two-dimensional (2D) shear flow of amorphous solids within\nvariants of an elastoplastic model, paying particular attention to spatial\ncorrelations and time fluctuations of, e.g., local stresses. The model is based\non the local alternation between an elastic regime and plastic events during\nwhich the local stress is redistributed. The importance of a fully tensorial\ndescription of the stress and of the inclusion of (coarse-grained) convection\nin the model is investigated; scalar and tensorial models yield very similar\nresults, while convection enhances fluctuations and breaks the spurious\nsymmetry between the flow and velocity gradient directions, for instance when\nshear localisation is observed. Besides, correlation lengths measured with\ndiverse protocols are discussed. One class of such correlation lengths simply\nscale with the spacing between homogeneously distributed, simultaneous plastic\nevents. This leads to a scaling of the correlation length with the shear rate\nas $\\dot{\\gamma}^{\\frac{-1}{2}}$ in 2D in the athermal regime, regardless of\nthe details of the model. The radius of the cooperative disk, defined as the\nnear-field region in which plastic events induce a stress redistribution that\nis not amenable to a mean-field treatment, notably follows this scaling. On the\nother hand, the cooperative volume measured from the four-point stress\nsusceptibility and its dependence on the system size and the shear rate are\nmodel-dependent.",
        "positive": "Switching Reversibly between Ultrastable and Unstable Foams: Ultrastable foams with an optimal foamability have been obtained using\nhydroxyl fatty acids tubes. The stabilization results from the adsorption of\nmonomers at the air-water interface preventing coalescence and coarsening and\nfrom the presence of tubes in the Plateau borders limiting the drainage. Upon\nheating, tubes transit to micelles, which induces foam destabilization. Such\nfoams are thus the first to have a temperature tunable stability."
    },
    {
        "anchor": "Construction and Refinement of Coarse-Grained Models: A general scheme, which includes constructions of coarse-grained (CG) models,\nweighted ensemble dynamics (WED) simulations and cluster analyses (CA) of\nstable states, is presented to detect dynamical and thermodynamical properties\nin complex systems. In the scheme, CG models are efficiently and accurately\noptimized based on a directed distance from original to CG systems, which is\nestimated from ensemble means of lots of independent observable in two systems.\nFurthermore, WED independently generates multiple short molecular dynamics\ntrajectories in original systems. The initial conformations of the trajectories\nare constructed from equilibrium conformations in CG models, and the weights of\nthe trajectories can be estimated from the trajectories themselves in\ngenerating complete equilibrium samples in the original systems. CA calculates\nthe directed distances among the trajectories and groups their initial\nconformations into some clusters, which correspond to stable states in the\noriginal systems, so that transition dynamics can be detected without requiring\na priori knowledge of the states.",
        "positive": "Deformable hard particles particles confined in a disordered porous\n  matrix: With suitably designed Monte Carlo simulations we have investigated the\nproperties of mobile, impenetrable, yet deformable particles that are immersed\ninto a porous matrix, the latter one realized via a frozen configuration of\nspherical particles. By virtue of a model put forward by Batista and Miller\n[Phys. Rev. Lett. {\\bf 105}, 088305 (2010)] the fluid particles can change\nunder the impact of their surrounding (i.e., either other fluid particles or\nthe matrix) their shape within the class of ellipsoids of revolution; such a\nchange in shape is related to an energy change which is fed into suitably\ndefined selection rules in the deformation \"moves\" of the Monte Carlo\nsimulations. This concept represents a simple, yet powerful model of realistic,\ndeformable molecules with complex internal structures (such as dendrimers or\npolymers). For the evaluation of the properties of the system we have used the\nwell-known quenched-annealed protocol (with its characteristic double average\nprescription) and have analysed the simulation data in terms of static\nproperties (radial distribution function and aspect ratio distribution of the\nellipsoids) and dynamic features (notably the mean squared displacement). Our\ndata provide evidence that the degree of deformability of the fluid particles\nhas a distinct impact on the aforementioned properties of the system."
    },
    {
        "anchor": "From the granular Leidenfrost state to buoyancy-driven convection: Grains inside a vertically vibrated box undergo a transition from a density\ninverted and horizontally homogeneous state, referred to as the granular\nLeidenfrost state, to a buoyancy-driven convective state. We perform a\nsimulational study of the precursors of such a transition, and quantify their\ndynamics as the bed of grains is progressively fluidized. The transition is\npreceded by transient convective states, which increase their correlation time\nas the transition point is approached. Increasingly correlated convective flows\nlead to density fluctuations, as quantified by the structure factor, that also\nshows critical behaviour near the transition point. The amplitude of the\nmodulations in the vertical velocity field are seen to be best described by a\nquintic supercritical amplitude equation with an additive noise term. The\nvalidity of such an amplitude equation, and previously observed collective\nsemi-periodic oscillations of the bed of grains, suggests a new interpretation\nof the transition analogous to a coupled chain of vertically vibrated damped\noscillators. Increasing the size of the container shows metastability of\nconvective states, as well as an overall invariant critical behaviour close to\nthe transition.",
        "positive": "Emulsion Destabilization by Squeeze Flow: There is a large debate on the destabilization mechanism of emulsions. We\npresent a simple technique using mechanical compression to destabilize\noil-in-water emulsions. Upon compression of the emulsion, the continuous\naqueous phase is squeezed out, while the dispersed oil phase progressively\ndeforms from circular to honeycomb-like shapes. The films that separate the oil\ndroplets are observed to thin and break at a critical oil/water ratio, leading\nto coalescence events. Electrostatic interactions and local droplet\nrearrangements do not determine film rupture. Instead, the destabilization\noccurs like an avalanche propagating through the system, starting at areas\nwhere the film thickness is smallest."
    },
    {
        "anchor": "On the importance of hydrodynamic interactions in polyelectrolyte\n  electrophoresis: The effect of hydrodynamic interactions on the free-solution electrophoresis\nof polyelectrolytes is investigated with coarse-grained molecular dynamics\nsimulations. By comparing the results to simulations with switched-off\nhydrodynamic interactions, we demonstrate their importance in modelling the\nexperimentally observed behaviour. In order to quantify the hydrodynamic\ninteractions between the polyelectrolyte and the solution, we present a novel\nway to estimate its effective charge. We obtain an effective friction that is\ndifferent from the hydrodynamic friction obtained from diffusion measurements.\nThis effective friction is used to explain the constant electrophoretic\nmobility for longer chains. To further emphasize the importance of hydrodynamic\ninteractions, we apply the model to end-labeled free-solution electrophoresis.",
        "positive": "Computer simulations of two-dimensional melting with dipole-dipole\n  interactions: We perform molecular dynamics and Monte Carlo simulations of two-dimensional\nmelting with dipole-dipole interactions. Both static and dynamic behaviors are\nexamined. In the isotropic liquid phase, the bond orientational correlation\nlength 6 and susceptibility 6 are measured, and the data are fitted to the\ntheoretical ansatz. An algebraic decay is detected for both spatial and\ntemporal bond orientational correlation functions in an intermediate\ntemperature regime, and it provides an explicit evidence for the existence of\nthe hexatic phase. From the finite-size scaling analysis of the global bond\norientational order parameter, the disclination unbinding temperature Ti is\nestimated. In addition, from dynamic Monte Carlo simulations of the positional\norder parameter, we extract the critical exponents at the dislocation unbinding\ntemperature Tm. All the results are in agreement with those from experiments\nand support the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory."
    },
    {
        "anchor": "Hydrostatic pressure dependence of the luminescence and Raman\n  frequencies in polyfluorene: We present studies of the photoluminescence (PL), absorption and Raman\nscattering from poly[2,7-(9,9'-bis(2-ethylhexyl))fluorene] under hydrostatic\npressures of 0-100 kbar at room temperature. The well-defined PL and associated\nvibronics that are observed at atmospheric pressure change dramatically around\n20 kbar in the bulk sample and at around 35 kbar for the thin film sample.\nBeyond these pressures the PL emission from the backbone is swamped by strong\npeaks due to aggregates and keto defects in the 2.1-2.6 eV region. The Raman\npeaks shift to higher energies and exhibit unexpected antiresonance lineshapes\nat higher pressures, indicating a strong electron-phonon interaction.",
        "positive": "Competition of hydrophobic and Coulombic interactions between nano-sized\n  solutes: The solvation of charged, nanometer-sized spherical solutes in water, and the\neffective, solvent-induced force between two such solutes are investigated by\nconstant temperature and pressure Molecular Dynamics simulations of model\nsolutes carrying various charge patterns. The results for neutral solutes agree\nwell with earlier findings, and with predictions of simple macroscopic\nconsiderations: substantial hydrophobic attraction may be traced back to strong\ndepletion (``drying'') of the solvent between the solutes. This hydrophobic\nattraction is strongly reduced when the solutes are uniformly charged, and the\ntotal force becomes repulsive at sufficiently high charge; there is a\nsignificant asymmetry between anionic and cationic solute pairs, the latter\nexperiencing a lesser hydrophobic attraction. The situation becomes more\ncomplex when the solutes carry discrete (rather than uniform) charge patterns.\nDue to antagonistic effects of the resulting hydrophilic and hydrophobic\n``patches'' on the solvent molecules, water is once more significantly depleted\naround the solutes, and the effective interaction reverts to being mainly\nattractive, despite the direct electrostatic repulsion between solutes.\nExamination of a highly coarse-grained configurational probability density\nshows that the relative orientation of the two solutes is very different in\nexplicit solvent, compared to the prediction of the crude implicit solvent\nrepresentation. The present study strongly suggests that a realistic modeling\nof the charge distribution on the surface of globular proteins, as well as the\nmolecular treatment of water are essential prerequisites for any reliable study\nof protein aggregation."
    },
    {
        "anchor": "Dynamics and Rheology of Ring-Linear Blend Semidilute Solutions in\n  Extensional Flow: Single Molecule Experiments: Ring polymers exhibit unique flow properties due to their closed chain\ntopology. Despite recent progress, we have not yet achieved a full\nunderstanding of the nonequilibrium flow behavior of rings in nondilute\nsolutions where intermolecular interactions greatly influence chain dynamics.\nIn this work, we directly observe the dynamics of DNA rings in semidilute\nring-linear polymer blends using single molecule techniques. We systematically\ninvestigate ring polymer relaxation dynamics from high extension and transient\nand steady-state stretching dynamics in planar extensional flow for a series of\nring-linear blends with varying ring fraction. Our results show multiple\nmolecular sub-populations for ring relaxation in ring-linear blends, as well as\nlarge conformational fluctuations for rings in steady extensional flow, even\nlong after the initial transient stretching process has subsided. We further\nquantify the magnitude and characteristic timescales of ring conformational\nfluctuations as a function of blend composition. Interestingly, we find that\nthe magnitude of ring conformational fluctuations follows a non-monotonic\nresponse with increasing ring fraction, first increasing at low ring fraction\nand then substantially decreasing at large ring fraction in ring-linear blends.\nA unique set of ring polymer conformations are observed during the transient\nstretching process, which highlights the prevalence of molecular individualism\nand supports the notion of complex intermolecular interactions in ring-linear\npolymer blends. Together with results from molecular simulations, our results\nsuggest that ring conformational fluctuations arise due to ring-linear\nthreading and intermolecular hydrodynamic interactions (HI). Taken together,\nour results provide a new molecular understanding of ring polymer dynamics in\nring-linear blends in nonequilibrium flow.",
        "positive": "Equilibrium morphology of tactoids in elastically anisotropic nematics: We study two dimensional tactoids in nematic liquid crystals by using a\n$\\mathbf{Q}$-tensor representation. A bulk free energy of the Maier-Saupe form\nwith eigenvalue constraints on $\\mathbf{Q}$, plus elastic terms up to cubic\norder in $\\mathbf{Q}$ are used to understand the effects of anisotropic\nanchoring and Frank-Oseen elasticity on the morphology of nematic-isotropic\ndomains. Further, a volume constraint is introduced to stabilize tactoids of\nany size at coexistence. We find that anisotropic anchoring results in\ndifferences in interface thickness depending on the relative orientation of the\ndirector at the interface, and that interfaces become biaxial for tangential\nalignment when anisotropy is introduced. For negative tactoids, surface defects\ninduced by boundary topology become sharper with increasing elastic anisotropy.\nOn the other hand, by parametrically studying their energy landscape, we find\nthat surface defects do not represent the minimum energy configuration in\npositive tactoids. Instead, the interplay between Frank-Oseen elasticity in the\nbulk, and anisotropic anchoring yields semi-bipolar director configurations\nwith non-circular interface morphology. Finally, we find that for growing\ntactoids the evolution of the director configuration is highly sensitive to the\nanisotropic term included in the free energy, and that minimum energy\nconfigurations may not be representative of kinetically obtained tactoids at\nlong times."
    },
    {
        "anchor": "A molecular dynamics computer simulation study of room-temperature ionic\n  liquids. I. Equilibrium solvation structure and free energetics: Solvation in 1-ethyl-3-methylmidazolium chloride and in\n1-ethyl-3-methylimidazolium hexafluorophosphate near equilibrium is\ninvestigated via molecular dynamics computer simulations with diatomic and\nbenzenelike molecules employed as probe solutes. It is found that\nelectrostriction plays an important role in both solvation structure and free\nenergetics. The angular and radial distributions of cations and anions become\nmore structured and their densities near the solute become enhanced as the\nsolute charge separation grows. Due to the enhancement in structural rigidity\ninduced by electrostriction, the force constant associated with solvent\nconfiguration fluctuations relevant to charge shift and transfer processes is\nalso found to increase. The effective polarity and reorganization free energies\nof these ionic liquids are analyzed and compared with those of highly polar\nacetonitrile. Their screening behavior of electric charges is also\ninvestigated.",
        "positive": "Simulation Study of Ion Diffusion in Charged Nanopores with Anchored\n  Terminal Groups: We present coarse-grained simulation results for enhanced ion diffusion in a\ncharged nanopore grafted with ionomer sidechains. The pore surface is\nhydrophobic and its diameter is varied from 2.0 nm to 3.7 nm. The sidechains\nhave from 2 to 16 monomers (united atom units) and contain sulfonate terminal\ngroups.\n  Our simulation results indicate a strong dependence of the ion diffusion\nalong the pore axis on the pore parameters. In the case of short sidechains and\nlarge pores the ions mostly occupy the pore wall area, where their distribution\nis strongly disturbed by their host sulfonates. In the case of short sidechains\nand narrow pores, the mobility of ions is strongly affected by the structuring\nand polarization effects of the water molecules. In the case of long\nsidechains, and when the sidechain sulfonates reach the pore center, a radial\ncharge separation occurs in the pore. Such charge separation suppresses the ion\ndiffusion along the pore axis.\n  An enhanced ion diffusion was found in the pores grafted with medium-size\nsidechains provided that the ions do not enter the central pore area, and the\nwater is less structured around the ions and sulfonates. In this case, the 3D\ndensity of the ions has a hollow-cylinder type shape with a smooth and\nuninterrupted surface. We found that the maximal ion diffusion has a linear\ndependence on the number of sidechain monomers. It is suggested that the\nmaximal ion diffusion along the pore axis is attained if the effective length\nof the sidechain extension into the pore center (measured as twice the gyration\nradius of the sidechain with the Flory exponent 1/4) is about 1/3 of the pore\nradius."
    },
    {
        "anchor": "Surface and smectic layering transitions in binary mixtures of parallel\n  hard rods: The surface phase behavior of binary mixtures of colloidal hard rods in\ncontact with a solid substrate (hard wall) is studied, with special emphasis on\nthe region of the phase diagram that includes the smectic A phase. The\ncolloidal rods are modelled as hard cylinders of the same diameter and\ndifferent lengths, in the approximation of perfect alignment. A\nfundamental--measure density functional is used to obtain equilibrium density\nprofiles and thermodynamic properties such as surface tensions and adsorption\ncoefficients. The bulk phase diagram exhibits nematic-smectic and\nsmectic-smectic demixing, with smectic phases having different compositions; in\nsome cases they are microfractionated. The calculated surface phase diagram of\nthe wall-nematic interface shows a very rich phase behavior, including layering\ntransitions and complete wetting at high pressures, whereby an infinitely thick\nsmectic film grows at the wall via an infinite sequence of stepwise\nfirst--order layering transitions. For lower pressures complete wetting also\nobtains, but here the smectic film grows in a continuous fashion. Finally, at\nvery low pressures, the wall-nematic interface exhibits critical adsorption by\nthe smectic phase, due to the second-order character of the bulk\nnematic-smectic transition.",
        "positive": "Dense Packings of Superdisks and the Role of Symmetry: We construct the densest known two-dimensional packings of superdisks in the\nplane whose shapes are defined by |x^(2p) + y^(2p)| <= 1, which contains both\nconvex-shaped particles (p > 0.5, with the circular-disk case p = 1) and\nconcave-shaped particles (0 < p < 0.5). The packings of the convex cases with p\n1 generated by a recently developed event-driven molecular dynamics (MD)\nsimulation algorithm [Donev, Torquato and Stillinger, J. Comput. Phys. 202\n(2005) 737] suggest exact constructions of the densest known packings. We find\nthat the packing density (covering fraction of the particles) increases\ndramatically as the particle shape moves away from the \"circular-disk\" point (p\n= 1). In particular, we find that the maximal packing densities of superdisks\nfor certain p 6 = 1 are achieved by one of the two families of Bravais lattice\npackings, which provides additional numerical evidence for Minkowski's\nconjecture concerning the critical determinant of the region occupied by a\nsuperdisk. Moreover, our analysis on the generated packings reveals that the\nbroken rotational symmetry of superdisks influences the packing characteristics\nin a non-trivial way. We also propose an analytical method to construct dense\npackings of concave superdisks based on our observations of the structural\nproperties of packings of convex superdisks."
    },
    {
        "anchor": "Analysis of multilayer electro-active tubes under different constraints: Dielectric elastomers are an emerging class of highly deformable\nelectro-active materials employed for electromechanical transduction\ntechnology. For practical applications, the design of such transducers requires\na model accounting for insulation of the active membrane, non-perfectly\ncompliant behaviour of the electrodes or interaction of the transducer with a\nsoft actuated body. To this end, a three-layer model, in which the active\nmembrane is embedded between two soft passive layers, can be formulated. In\nthis paper, the theory of nonlinear electro-elasticity for heterogeneous soft\ndielectrics is used to investigate the electromechanical response of multilayer\nelectro-active tubes---formed either by the active membrane only (single-layer\ntube) or by the coated active membrane (multilayer tube). Numerical results\nshowing the influence of the mechanical and the geometrical properties of the\nsoft coating layers on the electromechanical response of the active membrane\nare presented for different constraint conditions.",
        "positive": "Negative Differential Mobility and Trapping in Active Matter Systems: Using simulations, we examine the average velocity as a function of applied\ndrift force for active matter particles moving through a random obstacle array.\nWe find that for low drift force, there is an initial flow regime where the\nmobility increases linearly with drive, while for higher drift forces a regime\nof negative differential mobility appears in which the velocity decreases with\nincreasing drive due to the trapping of active particles behind obstacles. A\nfully clogged regime exists at very high drift forces when all the particles\nare permanently trapped behind obstacles. We find for increasing activity that\nthe overall mobility is nonmonotonic, with an enhancement of the mobility for\nsmall levels of activity and a decrease in mobility for large activity levels.\nWe show how these effects evolve as a function of disk and obstacle density,\nactive run length, drift force, and motor force."
    },
    {
        "anchor": "Direct determination of the size of basins of attraction of jammed\n  solids: We propose a free-energy based Monte-Carlo method to measure the volume of\npotential-energy basins in configuration space. Using this approach we can\nestimate the number of distinct potential-energy minima, even when this number\nis much too large to be sampled directly. We validate our approach by comparing\nour results with the direct enumeration of distinct jammed states in small\npackings of frictionless spheres. We find that the entropy of distinct packings\nis extensive and that the entropy of distinct hard-sphere packings must have a\nmaximum as a function of packing fraction.",
        "positive": "Effects of particle distribution on mechanical properties of\n  magneto-sensitive elastomers in a homogeneous magnetic field: We propose a theory which describes the mechanical behaviour of\nmagneto-sensitive elastomers (MSEs) under a uniform external magnetic field. We\nfocus on the MSEs with isotropic spatial distribution of magnetic particles. A\nmechanical model is used in which magnetic particles are arranged on the sites\nof three regular lattices: simple cubic, body-centered cubic and hexagonal\nclose-packed lattices. By this we extend our previous approach [Ivaneyko D. et\nal., Macromolecular Theory and Simulations, 2011, 20, 411] which used only a\nsimple cubic lattice for describing the spatial distribution of the particles.\nThe magneto-induced deformation and the Young's modulus of MSEs are calculated\nas functions of the strength of the external magnetic field. We show that the\nmagneto-mechanical behaviour of MSEs is very sensitive to the spatial\ndistribution of the magnetic particles. MSEs can demonstrate either uniaxial\nexpansion or contraction along the magnetic field and the Young's modulus can\nbe an increasing or decreasing function of the strength of the magnetic field\ndepending on the spatial distribution of the magnetic particles."
    },
    {
        "anchor": "Lateral diffusion of a protein on a fluctuating membrane: Measurements of lateral diffusion of proteins in a membrane typically assume\nthat the movement of the protein occurs in a flat plane. Real membranes,\nhowever, are subject to thermal fluctuations, leading to movement of an\ninclusion into the third dimension. We calculate the magnitude of this effect\nby projecting real three-dimensional diffusion onto an effective one on a flat\nplane. We consider both a protein that is free to diffuse in the membrane and\none that also couples to the local curvature. For a freely diffusing inclusion\nthe measured projected diffusion constant is up to 15% smaller than the actual\nvalue. Coupling to the curvature enhances diffusion significantly up to a\nfactor of two.",
        "positive": "Phase behaviour of semiflexible lattice polymers in poor-solvent\n  solution: mean-field theory and Monte Carlo simulations: We study a solution of interacting semiflexible polymers with curvature\nenergy in poor-solvent conditions on the d-dimensional cubic lattice using\nmean-field theory and Monte Carlo computer simulations. Building upon past\nstudies on a single chain, we construct a field-theory representation of the\nsystem and solve it within a mean-field approximation supported by Monte Carlo\nsimulations in d=3. A gas-liquid transition is found in the temperature-density\nplane that is then interpreted in terms of real systems. Interestingly, we find\nthis transition to be independent of the bending rigidity. Past classical\nFlory-Huggins and Flory mean-field results are shown to be particular cases of\nthis more general framework. Perspectives in terms of guiding experimental\nresults towards optimal conditions are also proposed."
    },
    {
        "anchor": "The component groups structure of DPPC bilayers obtained by specular\n  neutron reflectometry: Specular neutron reflectometry (SNR) was measured on a system of a floating\nbilayer consisting of 1,2-dipalmitoyl-d62-\\textit{sn}-glycero-3-phosphocholine\n(d62-diC16:0PC) deposited over a\n1,2-dibehenoyl-\\textit{sn}-glycero-3-phosphocholine (diC22:0PC) bilayer at 25\nand 55 {\\deg}C. The internal structure of lipid bilayers was described by a one\ndimensional scattering length density profile (SLDP) model, originally\ndeveloped for the evaluation of small angle scattering data. The corresponding\nmodel reflectivity curves successfully describe the experimental reflectivity\ncurves of a supported bilayer in the gel phase and a system of a floating\nbilayer in the liquid crystalline phase. The reflectivity data from the\nsupported bilayer were evaluated individually and served further as an input by\nthe data treatment of floating bilayer reflectivity curves. The results yield\ninternal structure of a deposited and floating bilayer on the level of\ncomponent groups of lipid molecules. The obtained structure of the floating\nd62-diC16:0PC bilayer displays high resemblance to the bilayer structure in the\nform of unilamellar vesicles, however, simultaneously it shows rate of\nfluctuations in comparison to unilamellar vesicle bilayers.",
        "positive": "Ice-water Interface: Correlation between Structure and Dynamics: To comprehend the complexities of the ice-water interface, we perform a study\nthat attempts to correlate the altered dynamics of water to its perturbed\nstructure at, and due to, the interface. The deviation from bulk values of\nstructural and dynamical quantities at the interface are obtained by computer\nsimulations. Water molecules are found to get exchanged between the ice-like\nand water-like domains of the interface with a time scale of the order of ~10\nps. To investigate the effect of interfaces in general, we study three other\nsystems, namely (i) water between two hydrophobic nano-slabs, (ii) water at\nprotein and (iii) DNA surfaces. In all these systems, we find that the\ndifference from bulk properties become negligible beyond ~1 nm, with structural\nfeatures converging to bulk values faster than the dynamical properties. Even\nin the case of the latter, we find that single-particle and collective\nproperties behave differently. The approach to bulk values is rapid except for\ncollective shell-dipole moments. We present a new insightful characterization\nof the surfaces by establishing a quantitative correlation between\ntetrahedrality order parameter (q_td) and dynamics by diffusion (D) and angular\njumps. In the ice-water system, we find that the variation of qtd, as we move\nfrom solid to the liquid phase, correlated well with D. The correlation is\nfound to be present in all the interfaces studied. Our results can be used to\nexplain the experimental outcomes of the likes of dielectric relaxation and\nsolvation dynamics."
    },
    {
        "anchor": "de Vries behavior of the electroclinic effect in the smectic-A* phase\n  near a biaxiality-induced smectic-A* -- smectic-C* tricritical point: Using a generalized Landau theory involving orientational, layering, tilt,\nand biaxial order parameters we analyze the smectic-A* and smectic-C* (Sm-A* --\nSm-C*) transition, showing that a combination of small orientational order and\nlarge layering order leads to Sm-A* -- Sm-C* transitions that are either\ncontinuous and close to tricriticality or first order. The model predicts that\nin such systems the increase in birefringence upon entry to the Sm-C* phase\nwill be especially rapid. It also predicts that the change in layer spacing at\nthe Sm-A* -- Sm-C* transition will be proportional to the orientational order.\nThese are two hallmarks of Sm-A* -- Sm-C* transitions in de Vries materials. We\nanalyze the electroclinic effect in the Sm-A* phase and show that as a result\nof the zero-field Sm-A* -- Sm-C* transition being either continuous and close\nto tricriticality or first order (i.e for systems with a combination of weak\norientational order and strong layering order) the electroclinic response of\nthe tilt will be unusually strong. Additionally, we investigate the associated\nelectrically induced change in birefringence and layer spacing, demonstrating\nde Vries behavior for each, i.e. an unusually large increase in birefringence\nand an unusually small layer contraction. Both the induced change in\nbirefringence and layer spacing are shown to scale quadratically with the\ninduced tilt angle.",
        "positive": "Jamming in two-dimensional packings: We investigate the existence of random close and random loose packing limits\nin two-dimensional packings of monodisperse hard disks. A statistical mechanics\napproach-- based on several approximations to predict the probability\ndistribution of volumes-- suggests the existence of the limiting densities of\nthe jammed packings according to their coordination number and compactivity.\nThis result has implications for the understanding of disordered states in the\ndisk packing problem as well as the existence of a putative glass transition in\ntwo dimensional systems."
    },
    {
        "anchor": "Interaction of Conical Membrane Inclusions: Effect of Lateral Tension: Considering two rigid conical inclusions embedded in a membrane subject to\nlateral tension, we study the membrane-mediated interaction between these\ninclusions that originates from the hat-shaped membrane deformations associated\nwith the cones. At non-vanishing lateral tensions, the interaction is found to\ndepend on the orientation of the cones with respect to the membrane plane. The\ninteraction of inclusions of equal orientation is repulsive at all distances\nbetween them, while the inclusions of opposite orientation repel each other at\nsmall separations, but attract each other at larger ones. Both the repulsive\nand attractive forces become stronger with increasing lateral tension. This is\ndifferent from what has been predicted on the basis of the same static model\nfor the case of vanishing lateral tension. Without tension, the inclusions\nrepel each other at all distances independently of their relative orientation.\nWe conclude that lateral tension may induce the aggregation of conical membrane\ninclusions.",
        "positive": "Viscoelasticity from a Microscopic Model of Dislocation Dynamics: It is shown that the dynamics of a two-dimensional crystal with a finite\nconcentration of dislocations, as well as vacancy and interstitial defects, is\ngoverned by the hydrodynamic equations of a viscoelastic medium. At the longest\nlength scales the viscoelasticity is described by the simplest Maxwell model,\nwhose shear and compressional relaxation times are obtained in terms of\nmicroscopic quantities, including the density of free dislocations. At short\nlength scales, bond orientational order effects become important and lead to\nwavevector dependent corrections to the relaxation times."
    },
    {
        "anchor": "Magnetization plateaus for spin-one bosons in optical lattices:\n  Stern-Gerlach experiments with strongly correlated atoms: We consider insulating states of spin-one bosons in optical lattices in the\npresence of a weak magnetic field. For the states with more than one atom per\nlattice site we find a series of quantum phase transitions between states with\nfixed magnetization and a canted nematic phase. In the presence of a global\nconfining potential, this unusual phase diagram leads to several novel\nphenomena, including formation of magnetization plateaus. We discuss how these\neffects can be observed using spatially resolved density measurements.",
        "positive": "Shear induced ordering in systems with competing interactions: A machine\n  learning study: When short-range attractions are combined with long-range repulsions in\ncolloidal particle systems, complex microphases can emerge. Here, we study a\nsystem of isotropic particles which can form lamellar structures or a\ndisordered fluid phase when temperature is varied. We show that at equilibrium\nthe lamellar structure crystallizes, while out of equilibrium the system forms\na variety of structures at different shear rates and temperatures above\nmelting. The shear-induced ordering is analyzed by means of principal component\nanalysis and artificial neural networks, which are applied to data of reduced\ndimensionality. Our results reveal the possibility of inducing ordering by\nshear, potentially providing a feasible route to the fabrication of ordered\nlamellar structures from isotropic particles."
    },
    {
        "anchor": "Elastic snap-through instabilities are governed by geometric symmetries: Many elastic structures exhibit rapid shape transitions between two possible\nequilibrium states: umbrellas become inverted in strong wind and hopper popper\ntoys jump when turned inside-out. This snap-through is a general motif for the\nstorage and rapid release of elastic energy, and it is exploited by many\nbiological and engineered systems from the Venus flytrap to mechanical\nmetamaterials. Shape transitions are known to be related to the type of\nbifurcation the system undergoes, however, to date, there is no general\nunderstanding of the mechanisms that select these bifurcations. Here we analyze\nnumerically and analytically two systems proposed in recent literature in which\nan elastic strip, initially in a buckled state, is driven through shape\ntransitions by either rotating or translating its boundaries. We show that the\ntwo systems are mathematically equivalent, and identify three cases that\nillustrate the entire range of transitions described by previous authors.\nImportantly, using reduction order methods, we establish the nature of the\nunderlying bifurcations and explain how these bifurcations can be predicted\nfrom geometric symmetries and symmetry-breaking mechanisms, thus providing\nuniversal design rules for elastic shape transitions.",
        "positive": "Finite-Width Bundle is Most Stable in a Solution with Salt: We applied the mean-field approach to a columnar bundle assembled by the\nparallel arrangement of stiff polyelectrolyte rods in a salt bath. The\nelectrostatic potential can be divided into two regions: inside the bundle for\ncondensed counter-ions, and outside the bundle for free small ions. To\ndetermine the distribution of condensed counter-ions inside the bundle, we use\na local self-consistent condition that depends on the charge density, the\nelectrostatic potential, and the net polarization. The results showed that,\nupon bundle formation, the electric charge of polyelectrolytes, even those\ninside the bundle, tend to survive in an inhomogeneous manner, and thus their\nwidth remains finite under thermal equilibrium because of the long-range effect\nof charge instability."
    },
    {
        "anchor": "Single particle fluctuations and directional correlations in driven hard\n  sphere glasses: Via event driven molecular dynamics simulations and experiments, we study the\npacking fraction and shear-rate dependence of single particle fluctuations and\ndynamic correlations in hard sphere glasses under shear. At packing fractions\nabove the glass transition, correlations increase as shear rate decreases: the\nexponential tail in the distribution of single particle jumps broadens and\ndynamic four-point correlations increase. Interestingly, however, upon\ndecreasing the packing fraction, a broadening of the exponential tail is also\nobserved, while dynamic heterogeneity is shown to decrease. An explanation for\nthis behavior is proposed in terms of a competition between shear and thermal\nfluctuations. Building upon our previous studies [Chikkadi et al, Europhys.\nLett. (2012)], we further address the issue of anisotropy of the dynamic\ncorrelations.",
        "positive": "Cut it out: Out-of-plane stresses in cell sheet folding of Volvox\n  embryos: The folding of cellular monolayers pervades embryonic development and\ndisease. It results from stresses out of the plane of the tissue, often caused\nby cell shape changes including cell wedging via apical constriction. These\nlocal cellular changes need not however be compatible with the global shape of\nthe tissue. Such geometric incompatibilities lead to residual stresses that\nhave out-of-plane components in curved tissues, but the mechanics and function\nof these out-of-plane stresses are poorly understood, perhaps because their\nquantification has proved challenging. Here, we overcome this difficulty by\ncombining laser ablation experiments and a mechanical model to reveal that such\nout-of-plane residual stresses exist and also persist during the inversion of\nthe spherical embryos of the green alga Volvox. We show how to quantify the\nmechanical properties of the curved tissue from its unfurling on ablation, and\nreproduce the tissue shape sequence at different developmental timepoints\nquantitatively by our mechanical model. Strikingly, this reveals not only clear\nmechanical signatures of out-of-plane stresses associated with cell shape\nchanges away from those regions where cell wedging bends the tissue, but also\nindicates an adaptive response of the tissue to these stresses. Our results\nthus suggest that cell sheet folding is guided mechanically not only by cell\nwedging, but also by out-of-plane stresses from these additional cell shape\nchanges."
    },
    {
        "anchor": "Dynamical instabilities of two-fluid interfaces in a porous medium: A\n  three-dimensional video imaging study: Two-fluid interfaces in porous media, an example of driven disordered\nsystems, were studied by a real time three-dimensional imaging technique with\npore scale resolution for a less viscous fluid displacing a more viscous one.\nWith increasing flow rate the interface transforms from flat to fingers and\nthence to droplets for both drainage and imbibition. The results compare and\ncontrast the effects of randomness, both physical (geometry of the pore space)\nand chemical (wettability of the fluids), on the dynamical instability and\nidentify the origin of the pore-scale processes that govern them.",
        "positive": "Dynamics of capillary coalescence and breakup: quasi-two-dimensional\n  nematic and isotropic droplets: For the first time we observed formation of small satellite droplets from the\nbridge at droplet coalescence. Investigations were made using a Hele-Shaw cell\nin the two-phase region at nematic-isotropic phase transition. In previous\nworks on coalescence it was considered that before start of coalescence there\nexists a bridge between the outer fluid connecting regions on the two sides of\nthe droplets (outer bridge). After start of coalescence a bridge connecting the\ntwo droplets appears (droplet bridge) and the outer bridge is broken. For the\nfirst time we have shown that there are coalescence processes when after start\nof coalescence both the droplet bridge and the outer bridge can exist. This\ncardinally changes the coalescence process. During the first coalescence stage\nthe size of the outer bridge decreases, the size of the droplet bridge\nincreases. During the second stage the outer bridge becomes unstable with\npinch-off, formation of pointed end domains, secondary instability, splitting\nof pointed end domains and formation of satellite droplets. Our work connects\ntwo areas of fluid dynamics: coalescence and breakup with formation of\nsatellite droplets."
    },
    {
        "anchor": "Non-Equilibrium Effects of Molecular Motors on Polymers: We present a generic coarse-grained model to describe molecular motors acting\non polymer substrates, mimicking, for example, RNA polymerase on DNA or kinesin\non microtubules. The polymer is modeled as a connected chain of beads; motors\nare represented as freely diffusing beads which, upon encountering the\nsubstrate, bind to it through a short-ranged attractive potential. When bound,\nmotors and polymer beads experience an equal and opposite active force,\ndirected tangential to the polymer; this leads to motion of the motors along\nthe polymer contour. The inclusion of explicit motors differentiates our model\nfrom other recent active polymer models. We study, by means of Langevin\ndynamics simulations, the effect of the motor activity on both the\nconformational and dynamical properties of the substrate. We find that activity\nleads, in addition to the expected enhancement of polymer diffusion, to an\neffective reduction of its persistence length. We discover that this effective\n\"softening\" is a consequence of the emergence of double-folded branches, or\nhairpins, and that it can be tuned by changing the number of motors or the\nforce they generate. Finally, we investigate the effect of the motors on the\nprobability of knot formation. Counter-intuitively our simulations reveal that,\neven though at equilibrium a more flexible substrate would show an increased\nknotting probability, motor activity leads to a marked decrease in the\noccurrence of knotted conformations with respect to equilibrium.",
        "positive": "Advanced iontronic spiking modes with multiscale diffusive dynamics in a\n  fluidic circuit: Fluidic iontronics is emerging as a distinctive platform for implementing\nneuromorphic circuits, characterized by its reliance on the same aqueous medium\nand ionic signal carriers as the brain. Drawing upon recent theoretical\nadvancements in both iontronic spiking circuits and in dynamic transport of\naqueous electrolytes through conical ion channels, which form fluidic\nmemristors, we expand the repertoire of proposed neuronal spiking dynamics in\niontronic circuits. Through a modelled circuit containing channels that carry a\nbipolar surface charge, we extract phasic bursting, mixed-mode spiking, tonic\nbursting, and threshold variability, all with spike voltages and frequencies\nwithin the typical range for mammalian neurons. These features are possible due\nto the strong dependence of the typical conductance memory retention time on\nthe channel length, enabling timescales varying from individual spikes to\nbursts of multiple spikes within a single circuit. These advanced forms of\nneuronal-like spiking support the exploration of aqueous iontronics as an\ninteresting platform for neuromorphic circuits."
    },
    {
        "anchor": "Phase Separation and Ripening in a Viscoelastic Gel: The process of phase separation in elastic solids and viscous fluids is of\nfundamental importance to the stability and function of soft materials. We\nexplore the dynamics of phase separation and domain growth in a viscoelastic\nmaterial such as a polymer gel. Using analytical theory and Monte Carlo\nsimulations we report a new domain growth regime, in which the domain size\nincreases algebraically with a ripening exponent $\\alpha$ that depends on the\nviscoelastic properties of the material. For a prototypical Maxwell material,\nwe obtain $\\alpha=1$, which is markedly different from the well-known Ostwald\nripening process with $\\alpha=1/3$. We generalize our theory to systems with\narbitrary power-law relaxation behavior and discuss our findings in the context\nof the long-term stability of materials as well as recent experimental results\non phase separation in cross-linked networks and cytoskeleton.",
        "positive": "Force and torque-free helical tail robot to study low Reynolds number\n  microorganism swimming: Helical propulsion is used by many microorganisms to swim in\nviscous-dominated environments. Their swimming dynamics are relatively well\nunderstood, but detailed study of the flow fields and actuation mechanisms are\nstill needed to realize wall effects and hydrodynamic interactions. In this\nletter, we describe the development of an autonomous swimming robot with a\nhelical tail that operates in the Stokes regime. The device uses a\nbattery-based power system with a miniature motor that imposes a rotational\nspeed to a helical tail. The speed, direction, and activation are controlled\nelectronically using an infrared remote control. Since the robot is about 5\ncentimeters long, we use highly viscous fluids to match the Reynolds number to\nbe $\\text{Re} \\lessapprox 0.1$. Measurements of swimming speeds are conducted\nfor a range of helical wavelengths, $\\lambda$, head geometries and rotation\nrates, $\\omega$. We provide comparisons of the experimental measurements with\nanalytical predictions derived from resistive force theory. This force and\ntorque-free neutrally-buoyant swimmer mimics the swimming strategy of bacteria\nmore closely than previously used designs and offers a lot of potential for\nfuture applications."
    },
    {
        "anchor": "On the potential of mean force of a sterically stabilized dispersion: The potential of mean force (PMF) of a colloidal dispersion under various\ncircumstances of current interest, such as varying solvent quality, polymer\ncoating thickness, and addition of electrostatic interaction is obtained from\nradial distribution functions available from the literature. They are based on\nan implicit solvent, molecular dynamics simulation study of a model titania\ndispersion that takes into account three major components to the interaction\nbetween colloidal particles, namely van der Waals attraction, repulsion between\npolymer coating layers, and a hard core particle repulsion. Additionally, a\nscreened form of the electrostatic interaction was included also. It is argued\nthat optimal conditions for dispersion stability can be derived from a\ncomparative analysis of the PMF under the different situations under study.\nThis thermodynamics based analysis is believed to be more accessible to\nspecialists working on the development of improved titania formulations than\nthat based on the more abstract, radial distribution functions.",
        "positive": "A Poisson-Boltzmann approach for a lipid membrane in an electric field: The behavior of a non-conductive quasi-planar lipid membrane in an\nelectrolyte and in a static (DC) electric field is investigated theoretically\nin the nonlinear (Poisson-Boltzmann) regime. Electrostatic effects due to\ncharges in the membrane lipids and in the double layers lead to corrections to\nthe membrane elastic moduli which are analyzed here. We show that, especially\nin the low salt limit, i) the electrostatic contribution to the membrane's\nsurface tension due to the Debye layers crosses over from a quadratic behavior\nin the externally applied voltage to a linear voltage regime. ii) the\ncontribution to the membrane's bending modulus due to the Debye layers\nsaturates for high voltages. Nevertheless, the membrane undulation instability\ndue to an effectively negative surface tension as predicted by linear\nDebye-H\\\"uckel theory is shown to persist in the nonlinear, high voltage\nregime."
    },
    {
        "anchor": "A study of deformation localization in nonlinear elastic lattices: The paper investigates localized deformation patterns resulting from the\nonset of instabilities in lattice structures. The study is motivated by\nprevious observations on discrete hexagonal lattices, where the onset of\nnon-uniform, quasi-static deformation patterns was associated with the loss of\nconvexity of the interaction potential, and where a variety of localized\ndeformations were found depending on loading configuration, lattice parameters\nand boundary conditions. These observations are here conducted on other lattice\nstructures, with the goal of identifying models of reduced complexity that are\nable to provide insight into the key parameters that govern the onset of\ninstability-induced localization. To this end, we first consider a\ntwo-dimensional square lattice consisting of point masses connected by in-plane\naxial springs and vertical ground springs. Results illustrate that depending on\nthe choice of spring constants and their relative values, the lattice exhibits\nin-plane or out-of plane instabilities leading to folding and unfolding. This\nmodel is further simplified by considering the one-dimensional case of a\nspring-mass chain sitting on an elastic foundation. A bifurcation analysis of\nthis lattice identifies the stable and unstable branches and illustrates its\nhysteretic and loading path-dependent behaviors. Finally, the lattice is\nfurther reduced to a minimal four mass model which undergoes a\nfolding/unfolding process qualitatively similar to the same process in the\ncentral part of a longer chain, helping our understanding of localization in\nmore complex systems. In contrast to the widespread assumption that\nlocalization is induced by defects or imperfections in a structure, this work\nillustrates that such phenomena can arise in perfect lattices as a consequence\nof the mode-shapes at the bifurcation points.",
        "positive": "Enlargement of Grains of Silica Colloidal Crystals by Centrifugation in\n  an Inverted-Triangle Internal-Shaped Container: We successfully fabricated large grains of silica colloidal crystals in an\ninverted-triangle internal-shaped container (inverted-triangle container) by\ncentrifugation. The largest grain in the container was much larger than that in\na container which has a flat bottom and constant width (flat-bottomed\ncontainer). The edged bottom of the inverted-triangle container eliminated the\nnumber of the grains, and then the broadened shape of the container effectively\nwidened the grains."
    },
    {
        "anchor": "Nonequilibrium glass transitions in the spherical $p$-spin model with\n  antisymmetric interactions: Our theoretical understanding of glassy dynamics is notoriously incomplete,\nand it is even more so when the glassy systems are driven out of equilibrium.\nAn extreme way to drive a system out of equilibrium is to introduce\nnonequilibrium dynamics at the microscopic level, e.g., through active forcing\nof the constituent particles or by having nonreciprocal interactions among the\nparticles. While glassy dynamics under active forcing has been studied by many,\nthe latter nonequilibrium scenario has received little attention. Here, I study\nthe glassy dynamics of the spherical $p$-spin model for $p\\geq 3$ with\nantisymmetric interactions, which generalizes reciprocal interactions in 2-body\ninteractions. The spherical $p$-spin model is an integral tool in the study of\ndynamical glass transition, and when antisymmetric interactions are added, I\nshow analytically and numerically that glassy behavior is generically\nsuppressed. Moreover, I obtain analytical expressions on the modified dynamical\nglass transition point and the Edward-Anderson parameter (i.e., the asymptotic\nplateau height value of the spin-spin correlation function) in the small\ndriving limit.",
        "positive": "Avalanche properties at the yielding transition: from externally\n  deformed glasses to active systems: We investigated the yielding phenomenon in the quasistatic limit using\nnumerical simulations of soft particles. Two different deformation scenarios,\nsimple shear (passive) and self-random force (active), and two interaction\npotentials were used. Our approach reveals that the exponents describing the\navalanche distribution are universal within the margin of error, showing\nconsistency between the passive and active systems. This indicates that any\ndifferences observed in the flow curves may have resulted from a dynamic effect\non the avalanche propagation mechanism. The evolution time required to reach a\nsteady state differs significantly between active and passive scenarios under\nsimilar conditions. However, we demonstrated that plastic avalanches under\nathermal quasistatic simulation dynamics display a similar scaling relationship\nbetween avalanche size and relaxation time, which cannot explain the different\nflow curves."
    },
    {
        "anchor": "Multifunctional Hyperuniform Cellular Networks: Optimality, Anisotropy\n  and Disorder: Disordered hyperuniform heterogeneous materials are new, exotic amorphous\nstates of matter that behave like crystals in the manner in which they suppress\nvolume-fraction fluctuations at large length scales, and yet are statistically\nisotropic with no Bragg peaks. It has recently been shown that disordered\nhyperuniform dielectric two-dimensional cellular network solids possess\ncomplete photonic band gaps comparable in size to photonic crystals, while at\nthe same time maintaining statistical isotropy, enabling waveguide geometries\nnot possible with photonic crystals. Motivated by these developments, we\nexplore other functionalities of various two-dimensional ordered and disordered\nhyperuniform cellular networks, including their effective thermal or electrical\nconductivities and elastic moduli. We establish the multifunctionality of a\nclass of such low-density networks by demonstrating that they maximize or\nvirtually maximize the effective conductivities and elastic moduli. This is\naccomplished using the machinery of homogenization theory, including optimal\nbounds and cross-property bounds, and statistical mechanics. We have identified\nordered and disordered hyperuniform low-weight cellular networks that are\nmultifunctional with respect to transport (e.g., heat dissipation and fluid\ntransport), mechanical and electromagnetic properties, which can be readily\nfabricated using 3D printing and lithographic technologies.",
        "positive": "Sound damping in ferrofluids: Magnetically enhanced compressional\n  viscosity: The damping of sound waves in magnetized ferrofluids is investigated and\nshown to be considerably higher than in the non-magnetized case. This fact may\nbe interpreted as a field-enhanced, effective compressional viscosity -- in\nanalogy to the ubiquitous field-enhanced shear viscosity that is known to be\nthe reason for many unusual behavior of ferrofluids under shear."
    },
    {
        "anchor": "Knots and Swelling in Protein Folding: Proteins can sometimes be knotted, and for many reasons the study of knotted\nproteins is rapidly becoming very important. For example, it has been proposed\nthat a knot increases the stability of a protein. Knots may also alter\nenzymatic activities and enhance binding. Moreover, knotted proteins may even\nhave some substantial biomedical significance in relation to illnesses such as\nParkinson's disease. But to a large extent the biological role of knots remains\na conundrum. In particular, there is no explanation why knotted proteins are so\nscarce. Here we argue that knots are relatively rare because they tend to cause\nswelling in proteins that are too short, and presently short proteins are\nover-represented in the Protein Data Bank (PDB). Using Monte Carlo simulations\nwe predict that the figure-8 knot leads to the most compact protein\nconfiguration when the number of amino acids is in the range of 200-600. For\nthe existence of the simplest knot, the trefoil, we estimate a theoretical\nupper bound of 300-400 amino acids, in line with the available PDB data.",
        "positive": "The crumpling transition of membranes driven by quantum fluctuations in\n  a D=epsilon expansion: We consider a D-dimensional fluid membrane in a D+1-dimensional embedding\nspace, subject to quantum fluctuations. The corresponding action is invariant\nunder coordinate transformations and depends only on the shape of the membrane\nand its variation, neglecting tangential degrees of freedom. We calculate the\nresulting field theory to one loop order in a D=epsilon expansion and find a\nquantum transition even at T=0."
    },
    {
        "anchor": "Anisotropic swim stress in active matter with nematic order: Active Brownian Particles (ABPs) transmit a swim pressure $\\Pi^{swim}=n\\zeta\nD^{swim}$ to the container boundaries, where $\\zeta$ is the drag coefficient,\n$D^{swim}$ is the swim diffusivity and $n$ is the uniform bulk number density\nfar from the container walls. In this work we extend the notion of the\nisotropic swim pressure to the anisotropic tensorial swim stress\n$\\mathbf{\\sigma}^{swim} = - n \\zeta \\mathbf{D}^{swim}$, which is related to the\nanisotropic swim diffusivity $\\mathbf{D}^{swim}$. We demonstrate this\nrelationship with ABPs that achieve nematic orientational order via a bulk\nexternal field. The anisotropic swim stress is obtained analytically for dilute\nABPs in both 2D and 3D systems, and the anisotropy is shown to grow\nexponentially with the strength of the external field. We verify that the\nnormal component of the anisotropic swim stress applies a pressure\n$\\Pi^{swim}=-(\\mathbf{\\sigma}^{swim}\\cdot\\mathbf{n})\\cdot\\mathbf{n}$ on a wall\nwith normal vector $\\mathbf{n}$, and, through Brownian dynamics simulations,\nthis pressure is shown to be the force per unit area transmitted by the active\nparticles. Since ABPs have no friction with a wall, the difference between the\nnormal and tangential stress components -- the normal stress difference --\ngenerates a net flow of ABPs along the wall, which is a generic property of\nactive matter systems.",
        "positive": "Polystyrene clusters captured by acoustic tweezers spontaneously\n  rupturing: Numerous investigations have demonstrated that standing acoustic waves can\ntrap particles that range in size from microns to millimeters. Powerful\ntweezers may trap clusters of particles rather than single ones because their\ntrapping radius is substantially larger than the size of the trapped particle.\nIn this study, clusters of polystyrene particles measuring 450 microns in size\nthat were suspended in an ionic surfactant solution were trapped at the nodes\nof acoustic standing waves. The correlation between surfactant concentration\nand threshold radius is examined, and potential mechanisms that could be\nresponsible for the phenomenon are investigated. The findings demonstrated that\nadding polystyrene made clusters unstable and caused them to spontaneously\nrupture. Additionally, studies revealed that the cluster began to undergo\nspontaneous sequential ruptures after its radius above a particular threshold."
    },
    {
        "anchor": "Jellium and Cell Model for Titratable Colloids with Continuous Size\n  Distribution: A good understanding and determination of colloidal interactions is paramount\nto comprehend and model the thermodynamic and structural properties of\ncolloidal suspensions. In concentrated aqueous suspensions of colloids with a\ntitratable surface charge, this determination is, however, complicated by the\ndensity dependence of the effective pair potential due to both the many-body\ninteractions and the charge regulation of the colloids. In addition, colloids\ngenerally present a size distribution which results in a virtually infinite\ncombination of colloid pairs. In this paper we develop two methods and describe\nthe corresponding algorithms to solve this problem for arbitrary size\ndistributions. An implementation in Nim is also provided.The methods, inspired\nby the seminal work of Torres et al., are based on a generalization of the cell\nand renormalized jellium models to polydisperse suspensions of spherical\ncolloids with a charge regulating boundary condition. The latter is described\nby the one-pK-Stern model. The predictions of the models are confronted to the\nequations of state of various commercially available silica dispersions. The\nrenormalized Yukawa parameters (effective charges and screening lengths) are\nalso calculated. The importance of size and charge polydispersity as well as\nthe validity of these two models are discussed in light of the results.",
        "positive": "Softness Matters: Effects of Compression on the Behavior of Adsorbed\n  Microgels at Interfaces: Deformable colloids and macromolecules adsorb at interfaces, as they decrease\nthe interfacial energy between the two media. The deformability, or softness,\nof these particles plays a pivotal role in the properties of the interface. In\nthis study, we employ a comprehensive \\emph{in situ} approach, combining\nneutron reflectometry with molecular dynamics simulations, to thoroughly\nexamine the profound influence of softness on the structure of microgel\nLangmuir monolayers under compression. Lateral compression of both hard and\nsoft microgel particle monolayers induces substantial structural alterations,\nleading to an amplified protrusion of the microgels into the aqueous phase.\nHowever, a critical distinction emerges: hard microgels are pushed away from\nthe interface, in stark contrast to the soft ones, which remain steadfastly\nanchored to it. Concurrently, on the air-exposed side of the monolayer, lateral\ncompression induces a flattening of the surface of the hard monolayer. This\nphenomenon is not observed for the soft particles as the monolayer is already\nextremely flat even in the absence of compression. These findings significantly\nadvance our understanding of the pivotal role of softness on both the\nequilibrium phase behavior of the monolayer and its effect when soft colloids\nare used as stabilizers of responsive interfaces and emulsions."
    },
    {
        "anchor": "An efficient Cellular Potts Model algorithm that forbids cell\n  fragmentation: The Cellular Potts Model (CPM) is a lattice based modeling technique which is\nwidely used for simulating cellular patterns such as foams or biological\ntissues. Despite its realism and generality, the standard Monte Carlo algorithm\nused in the scientific literature to evolve this model preserves connectivity\nof cells on a limited range of simulation temperature only. We present a new\nalgorithm in which cell fragmentation is forbidden for all simulation\ntemperatures. This allows to significantly enhance realism of the simulated\npatterns. It also increases the computational efficiency compared with the\nstandard CPM algorithm even at same simulation temperature, thanks to the time\nspared in not doing unrealistic moves. Moreover, our algorithm restores the\ndetailed balance equation, ensuring that the long-term stage is independent of\nthe chosen acceptance rate and chosen path in the temperature space.",
        "positive": "Analysis of the Interplay of Quantum Phases and Nonlinearity Applied to\n  Dimers with Anharmonic Interactions: We extend our analysis of the effects of the interplay of quantum phases and\nnonlinearity to address saturation effects in small quantum systems.\n  We find that initial phases dramatically control the dependence of\nself-trapping on initial asymmetry of quasiparticle population and can compete\nor act with nonlinearity as well as saturation effects. We find that there is a\nminimum finite saturation value in order to obtain self-trapping that crucially\ndepends on the initial quasiparticle phases and present a detailed\nphase-diagram in terms of the control parameters of the system: nonlinearity\nand saturation."
    },
    {
        "anchor": "A Transition State Theory for Calculating Hopping Times and Diffusion in\n  Highly Confined Fluids: Monte Carlo simulation is used to study the dynamical crossover from single\nfile diffusion to normal diffusion in fluids confined to narrow channels. We\nshow that the long time diffusion coefficients for a series of systems\ninvolving hard and soft interaction potentials can be described in terms of a\nhopping time that measures the time it takes for a particle to escape the cage\nformed by its neighbors in the pore. Free energy barriers for the particle\nhopping process are calculated and used to show that transition state theory\neffectively describes the hopping time for all the systems studied, over a\nrange of pore diameters. Our work suggests that the combination of hopping\ntimes and transition state theory offers a useful and general framework to\ndescribe the dynamics of these highly confined fluids.",
        "positive": "Master curves for the stress tensor invariants in stationary states of\n  static granular beds. Implications for the thermodynamic phase space: We prepare static granular beds under gravity in different stationary states\nby tapping the system with pulsed excitations of controlled amplitude and\nduration. The macroscopic state---defined by the ensemble of static\nconfigurations explored by the system tap after tap---for a given tap intensity\nand duration is studied in terms of volume, V, and force moment tensor, \\Sigma.\nIn a previous paper [Pugnaloni et al., Phys. Rev. E 82, 050301(R) (2010)], we\nreported evidence supporting that such macroscopic states cannot be fully\ndescribed by using only V or \\Sigma, apart from the number of particles N. In\nthis work, we present an analysis of the fluctuations of these variables that\nindicates that V and \\Sigma may be sufficient to define the macroscopic states.\nMoreover, we show that only one of the invariants of \\Sigma is necessary, since\neach component of \\Sigma falls onto a master curve when plotted as a function\nof Tr(\\Sigma). This implies that these granular assemblies have a common shape\nfor the stress tensor, even though it does not correspond to the hydrostatic\ntype. Although most results are obtained by molecular dynamics simulations, we\npresent supporting experimental results."
    },
    {
        "anchor": "A criterion to identify the equilibration time in lipid bilayer\n  simulations: With the aim of establishing a criterion for identifying when a lipid bilayer\nhas reached steady state using the molecular dynamics simulation technique,\nlipid bilayers of different composition in their liquid crystalline phase were\nsimulated in aqueous solution in presence of CaCl$_2$ as electrolyte, at\ndifferent concentration levels. In this regard, we used two different lipid\nbilayer systems: one composed by 288 DPPC (DiPalmitoylPhosphatidylCholine) and\nanother constituted by 288 DPPS (DiPalmitoylPhosphatidylSerine). In this sense,\nfor both type of lipid bilayers, we have studied the temporal evolution of some\nlipids properties, such as the surface area per lipid, the deuterium order\nparameter, the lipid hydration and the lipid-calcium coordination. From their\nanalysis, it became evident how each property has a different time to achieve\nequilibrium. The following order was found, from faster property to slower\nproperty: coordination of ions $\\approx$ deuterium order parameter $>$ area per\nlipid $\\approx$ hydration. Consequently, when the hydration of lipids or the\nmean area per lipid are stable, we can ensure that the lipid membrane has\nreached the steady state.",
        "positive": "Dissipation in Dynamics of a Moving Contact Line: The dynamics of the deformations of a moving contact line is studied assuming\ntwo different dissipation mechanisms. It is shown that the characteristic\nrelaxation time for a deformation of wavelength $2\\pi/|k|$ of a contact line\nmoving with velocity $v$ is given as $\\tau^{-1}(k)=c(v) |k|$. The velocity\ndependence of $c(v)$ is shown to drastically depend on the dissipation\nmechanism: we find $c(v)=c(v=0)-2 v$ for the case when the dynamics is governed\nby microscopic jumps of single molecules at the tip (Blake mechanism), and\n$c(v)\\simeq c(v=0)-4 v$ when viscous hydrodynamic losses inside the moving\nliquid wedge dominate (de Gennes mechanism). We thus suggest that the debated\ndominant dissipation mechanism can be experimentally determined using\nrelaxation measurements similar to the Ondarcuhu-Veyssie experiment [T.\nOndarcuhu and M. Veyssie, Nature {\\bf 352}, 418 (1991)]."
    },
    {
        "anchor": "Depleted Depletion Drives Polymer Swelling in Poor Solvent Mixtures: Macromolecular solubility in solvent mixtures often exhibit striking and\nparadoxical nature. For example, when two well miscible poor solvents for a\ngiven polymer are mixed together, the same polymer may swell within\nintermediate mixing ratios. We combine computer simulations and theoretical\narguments to unveil the first microscopic, generic origin of this\ncollapse-swelling-collapse scenario. We show that this phenomenon naturally\nemerges at constant pressure in mixtures of purely repulsive components,\nespecially when a delicate balance of the entropically driven depletion\ninteractions is achieved.",
        "positive": "Molecular dynamics simulations of active Brownian particles in dilute\n  suspension: diffusion in free space and distribution in confinement: In this work, we report a new method to simulate active Brownian particles\n(ABPs) in molecular dynamics (MD) simulations. Immersed in a fluid, each ABP\nconsists of a head particle and a spherical phantom region of fluid where the\nflagellum of a microswimmer takes effect. The orientation of the active\nparticle is governed by a stochastic dynamics, with the orientational\npersistence time determined by the rotational diffusivity. To hydrodynamically\ndrive the active particle as a pusher, a pair of active forces are exerted on\nthe head particle and the phantom fluid region respectively. The active\nvelocity measured along the particle orientation is proportional to the\nmagnitude of the active force. The effective diffusion coefficient of the\nactive particle is first measured in free space, showing semi-quantitative\nagreement with the analytical result predicted by a minimal model for ABPs. We\nthen turn to the probability distribution of the active particle in confinement\npotential. We find that the stationary particle distribution undergoes an\nevolution from the Boltzmann-type to non-Boltzmann distribution as the\norientational persistence time is increased relative to the relaxation time in\nthe potential well. From the stationary distribution in confinement potential,\nthe active part of the diffusion coefficient is measured and compared to that\nobtained in free space, showing a good semi-quantitative agreement while the\norientational persistence time varies greatly relative to the relaxation time."
    },
    {
        "anchor": "Coarse-Grained Modeling of a Deformable Nematic Vesicle: We develop a coarse-grained particle-based model to simulate membranes with\nnematic liquid-crystal order. The coarse-grained particles form vesicles which,\nat low temperature, have orientational order in the local tangent plane. As the\nstrength of coupling between the nematic director and the vesicle curvature\nincreases, the vesicles show a morphology transition from spherical to prolate\nand finally to a tube. We also observe the shape and defect arrangement around\nthe tips of the prolate vesicle.",
        "positive": "Jammed disks of two sizes in a narrow channel: A granular-matter model is exactly solved, where disks of two sizes and\nweights in alternating sequence are confined to a narrow channel. The axis of\nthe channel is horizontal and its plane vertical. Disk sizes and channel width\nare such that under jamming no disks remain loose and all disks touch one wall.\nJammed microstates are characterized via statistically interacting particles\nconstructed out of two-disk tiles. Jammed macrostates depend on measures of\nexpansion work, gravitational potential energy, and intensity of random\nagitations before jamming. The dependence of configurational entropy on excess\nvolume exhibits a critical point."
    },
    {
        "anchor": "Emergence of Living Chiral Superlattice from Biased-Active Particles: We introduce for the first time a general model of biased-active particles,\nwhere the direction of the active force has a biased angle from the principle\norientation of the anisotropic interaction between particles. We find that a\nhighly ordered living superlattice consisting of small clusters with dynamic\nchirality emerges in a mixture of such biased-active particles and passive\nparticles. We show that the biased-propulsion-induced instability of\nactive-active particle pairs and rotating of active-passive particle pairs are\nthe very reason for the superlattice formation. In addition, a\nbiased-angle-dependent optimal active force is most favorable for both the\nlong-range order and global dynamical chirality of the system. Our results\ndemonstrate the proposed biased-active particle providing a great opportunity\nto explore a variety of new fascinating collective behaviors beyond\nconventional active particles.",
        "positive": "Analogy of the slow dynamics between the supercooled liquid and the\n  supercooled plastic crystal states of difluorotetrachloroethane: Slow dynamics of difluorotetrachloroethane in both supercooled plastic\ncrystal and supercooled liquid states have been investigated from Molecular\nDynamics simulations. The temperature and wave-vector dependence of collective\ndynamics in both states are probed using coherent dynamical scattering\nfunctions $S(Q,t)$. Our results confirm the strong analogy between molecular\nliquids and plastic crystals for which $\\alpha$-relaxation times and\nnon-ergodicity parameters are controlled by the non trivial static correlations\n$S(Q)$ as predicted by the Mode Coupling Theory. The use of infinitely thin\nneedles distributed on a lattice as model of plastic crystals is discussed."
    },
    {
        "anchor": "An immersed boundary method for the fluid-structure interaction of\n  slender flexible structures in viscous fluid: This paper presents a numerical method for the simulation of fluid-structure\ninteraction specifically tailored to interactions between Newtonian fluids and\na large number of slender viscoelastic Cosserat rods. Because of their high\nflexibility and low weight the rods considered here exhibit large deflections,\neven under moderate fluid loads. Their motion, in turn, modifies the flow so\nthat fluid and structures are strongly coupled to each other which is\nnumerically very challenging. The paper proposes a new coupling approach based\non an immersed boundary method which improves upon existing methods for this\nproblem. It is numerically stable and exempt from any global iteration between\nthe fluid part and the structure part, thus yielding high stability and low\ncomputational cost of the coupling scheme. The contribution presents the\nunderlying methodology and its algorithmic realization, including an assessment\nof accuracy and convergence by systematic studies. Various validation cases\nillustrate performance and versatility of the proposed method.",
        "positive": "Thermoelectric ratchet effect for charge carriers with hopping dynamics: We show that the huge Seebeck coefficients observed recently for ionic\nconductors, arise from a ratchet effect where activated jumps between neighbor\nsites are rectified by a temperature gradient, thus driving mobile ions towards\nthe cold. For complex systems with mobile molecules like water or polyethylene\nglycol, there is an even more efficient diffusiophoretic transport mechanism,\nproportional to the thermally induced concentration gradient of the molecular\ncomponent. Without free parameters, our model describes experiments on the\nionic liquid EMIM-TFSI and hydratedNaPSS, and it qualitatively accounts for\npolymer electrolyte membranes with Seebeck coefficients of hundreds of $k_B/e$."
    },
    {
        "anchor": "Spheroidal and Nanocrystal Structures From Carbodiimide Crosslinking\n  Reaction With RADA16: RADA16 is a widely studied polypeptide known for its ability to self-assemble\ninto $\\beta$-sheets that form nanofibers. Here we show that it is possible to\nself-crosslink the molecule via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide\nhydrochloride (EDC) as aqueous solutions. The product results in a mix of\nnanocrystals and near micron-size spherules. SEM and TEM pictures provide a\nview of the structures and nano tracking analysis give their size\ndistributions. FTIR analysis provides evidence for the existence of a\ncrosslinking reaction.",
        "positive": "Structural nonequilibrium forces in driven colloidal systems: We identify a structural one-body force field that sustains spatial\ninhomogeneities in nonequilibrium overdamped Brownian many-body systems. The\nstructural force is perpendicular to the local flow direction, it is free of\nviscous dissipation, it is microscopically resolved in both space and and time,\nand it can stabilize density gradients. From the time evolution in the exact\n(Smoluchowski) low-density limit, Brownian dynamics simulations and a novel\npower functional approximation, we obtain a quantitative understanding of\nviscous and structural forces, including memory and shear migration."
    },
    {
        "anchor": "A unified description of gravity- and kinematics-induced segregation\n  forces in dense granular flows: Particle segregation is common in natural and industrial processes involving\nflowing granular materials. Complex, and seemingly contradictory, segregation\nphenomena have been observed for different boundary conditions and forcing.\nUsing discrete element method simulations, we show that segregation of a single\nparticle intruder can be described in a unified manner across different flow\nconfigurations. A scaling relation for the net segregation force is obtained by\nmeasuring forces on an intruder particle in controlled-velocity flows where\ngravity and flow kinematics are varied independently. The scaling law consists\nof two additive terms: a buoyancy-like gravity-induced pressure gradient term\nand a shear rate gradient term, both of which depend on the particle size\nratio. The shear rate gradient term reflects a kinematics-driven mechanism\nwhereby larger (smaller) intruders are pushed toward higher (lower) shear rate\nregions. The scaling is validated, without refitting, in wall-driven flows,\ninclined wall-driven flows, vertical silo flows, and free surface flows down\ninclines. Comparing the segregation force to the intruder weight results in\npredictions of the segregation direction that match experimental and\ncomputational results for various flow configurations.",
        "positive": "Colloidal Gels Tuned by Oscillatory Shear: We examine microstructural and mechanical changes which occur during\noscillatory shear flow and reformation after flow cessation of an intermediate\nvolume fraction colloidal gel using rheometry and Brownian Dynamics (BD)\nsimulations. A model depletion colloid-polymer mixture is used, comprising of a\nhard sphere colloidal suspension with the addition of non-adsorbing linear\npolymer chains. Results reveal three distinct regimes depending on the strain\namplitude of oscillatory shear. Large shear strain amplitudes fully break the\nstructure which results into a more homogenous and stronger gel after flow\ncessation. Intermediate strain amplitudes densify the clusters and lead to\nhighly heterogeneous and weak gels. Shearing the gel to even lower strain\namplitudes creates a less heterogonous stronger solid. These three regimes of\nshearing are connected to the microscopic shear-induced structural\nheterogeneity. A comparison with steady shear flow reveals that the latter does\nnot produce structural heterogeneities as large as oscillatory shear. Therefore\noscillatory shear is a much more efficient way of tuning the mechanical\nproperties of colloidal gels. Moreover, colloidal gels presheared at large\nstrain amplitudes exhibit a distinct nonlinear response characterized largely\nby a single yielding process while in those presheared at lower rates a two\nstep yield process is promoted due to the creation of highly heterogeneous\nstructures."
    },
    {
        "anchor": "Direct observation of phase transitions in Archimedean trunctated\n  tetrahedrons under quasi-2D confinement: Colloidal crystals are used to understand fundamentals of atomic\nrearrangements in condensed matter and build complex metamaterials with unique\nfunctionalities. Simulations predict a multitude of self-assembled crystal\nstructures from anisotropic colloids, but these shapes have been challenging to\nfabricate. Here, we use two-photon lithography to fabricate Archimedean\ntruncated tetrahedrons and self-assemble them under quasi-2D confinement. Under\na small gravitational potential, these particles self-assemble into a hexatic\nphase, which has not yet been observed or reported for this shape. Under\nadditional gravitational potential, the hexatic phase transitions into a\nquasi-diamond two-unit basis. In-situ imaging reveal this phase transition is\ninitiated by an out-of-plane rotation of a particle at a crystalline defect and\ncauses a chain reaction of neighboring particle rotations. Our results provide\na framework of studying different structures from hard-particle self-assembly\nand demonstrates the ability to use confinement to induce unusual phases.",
        "positive": "Fluid-fluid demixing transitions in colloid--polyelectrolyte star\n  mixtures: We derive effective interaction potentials between hard, spherical colloidal\nparticles and star-branched polyelectrolytes of various functionalities and\nsmaller size than the colloids. The effective interactions are based on a\nDerjaguin-like approximation, which is based on previously derived potentials\nacting between polyelectrolyte stars and planar walls. On the basis of these\ninteractions we subsequently calculate the demixing binodals of the binary\ncolloid--polyelectrolyte star mixture, employing standard tools from\nliquid-state theory. We find that the mixture is indeed unstable at moderately\nhigh overall concentrations. The system becomes more unstable with respect to\ndemixing as the star functionality and the size ratio grow."
    },
    {
        "anchor": "Near-Wall Dynamics of Concentrated Hard-Sphere Suspensions: Comparison\n  of Evanescent Wave DLS Experiments, Virial Approximation and Simulations: In this article we report on a study of the near-wall dynamics of suspended\ncolloidal hard spheres over a broad range of volume fractions. We present a\nthorough comparison of experimental data with predictions based on a virial\napproximation and simulation results. We find that the virial approach\ndescribes the experimental data reasonably well up to a volume fraction of\n$\\phi=0.25$ which provides us with a fast and non-costly tool for the analysis\nand prediction of Evanescent Wave DLS data. Based on this we propose a new\nmethod to assess the near-wall self-diffusion at elevated density. Here, we\nqualitatively confirm earlier results [Michailidou et al., Phys. Rev. Lett.,\n2009, 102, 068302], which indicate that many-particle hydrodynamic interactions\nare diminished by the presence of the wall at increasing volume fractions as\ncompared to bulk dynamics. Beyond this finding we show that this diminishment\nis different for the particle motion normal and parallel to the wall.",
        "positive": "Quantitative Microscale Thermometry in Droplets Loaded with Gold\n  Nanoparticles: Gold nanoparticles (AuNPs) are increasingly used for their thermoplasmonic\nproperties, i.e. their ability to convert light into heat upon plasmon\nresonance. However, measuring temperature gradients generated at the microscale\nby assemblies of AuNPs remains challenging, especially when they are randomly\ndistributed in three dimensions. Here, we introduce a label-free thermometry\napproach, combining optical wavefront microscopy and numerical simulations, to\ninfer the heating power dissipated by a three-dimensional model system\nconsisting in emulsion microdroplets loaded with AuNPs. This approach gives\naccess to the temperature reached in the core of droplets upon irradiation\nwithout need of extrinsic calibration. These quantitative results are validated\nqualitatively via the observation of the phase transition of a thermoresponsive\npolymer added in the droplet as an in situ thermal probe. This versatile\nthermometry approach is promising for non-invasive temperature measurements in\nvarious three-dimensional microsystems involving AuNPs as colloidal heat\nsources, such as several light-responsive drug delivery systems."
    },
    {
        "anchor": "Design of patchy rhombi: from close-packed tilings to open lattices: In the realm of functional materials, the production of two-dimensional\nstructures with tuneable porosity is of paramount relevance for many practical\napplications: surfaces with regular arrays of pores can be used for selective\nadsorption or immobilization of guest units that are complementary in shape\nand/or size to the pores, thus achieving, for instance, selective filtering or\nwell-defined responses to external stimuli. The principles that govern the\nformation of such structures are valid at both the molecular and the colloidal\nscale. Here we provide simple design directions to combine the anisotropic\nshape of the building units -- either molecules or colloids -- and selective\ndirectional bonding. Using extensive computer simulations we show that regular\nrhombic platelets decorated with attractive and repulsive interaction sites\nlead to specific tilings, going smoothly from close-packed arrangements to open\nlattices. The rationale behind the rich tiling scenario observed can be\ndescribed in terms of steric incompatibilities, unsatisfied bonding geometries\nand interplays between local and long-range order.",
        "positive": "Molecular Dynamics Simulations of Microscopic Structural Transition and\n  Macroscopic Mechanical Properties of Magnetic Gels: Magnetic gels with embedded micro/nano-sized magnetic particles in\ncrosslinked polymer networks can be actuated by external magnetic fields, with\nchanges in their internal microscopic structures and macroscopic mechanical\nproperties. We investigate the responses of such magnetic gels to an external\nmagnetic field, by means of coarse-grained molecular dynamics simulations. We\nfind that the dynamics of magnetic particles are determined by the interplay of\nbetween magnetic dipole-dipole interactions, polymer elasticity and thermal\nfluctuations. The corresponding microscopic structures formed by the magnetic\nparticles such as elongated chains can be controlled by the external magnetic\nfield. Furthermore, the magnetic gels can exhibit reinforced macroscopic\nmechanical properties, where the elastic modulus increases algebraically with\nthe magnetic moments of the particles in the form of\n$\\propto(m-m_{\\mathrm{c}})^{2}$ when magnetic chains are formed. This\nsimulation work can not only serve as a tool for studying the microscopic and\nthe macroscopic responses of the magnetic gels, but also facilitate future\nfabrications and practical controls of magnetic composites with desired\nphysical properties."
    },
    {
        "anchor": "Role of microscopic phase separation in gelation of aqueous gelatin\n  solutions: Using a unique home-made cell for four-contact impedance spectroscopy of\nconductive liquid samples, we establish the existence of two low frequency\nconductivity relaxations in aqueous solutions of gelatin, in both liquid and\ngel state. A comparison with diffusion measurements using pulsed field gradient\nNMR shows that the faster relaxation process is due to gelatin macromolecule\nself-diffusion. This single molecule diffusion is mostly insensitive to the\nmacroscopic state of the sample, implying that the gelation of gelatin is not a\npercolative phenomenon, but is caused by aggregation of triple helices into a\nsystem-spanning fibre network.",
        "positive": "Studies of a weak polyampholyte at the air-buffer interface: The effect\n  of varying pH and ionic strength: We have carried out experiments to probe the static and dynamic interfacial\nproperties of $\\beta$--casein monolayers spread at the air-buffer interface,\nand analysed these results in the context of models of weak polyampholytes.\nMeasurements have been made systematically over a wide range of ionic strength\nand pH. In the semi-dilute regime of surface concentration a scaling exponent,\nwhich can be linked to the degree of chain swelling, is found. This shows that\nat pH close to the isoelectric point, the protein is compact. At pH away from\nthe isoelectric pH the protein is extended. The transition between compact and\nextended states is continuous. As a function of increasing ionic strength, we\nobserve swelling of the protein at the isoelectric pH but contraction of the\nprotein at pH values away from it. These behaviours are typical of a those\npredicted theoretically for a weak polyampholyte. Dilational moduli\nmeasurements, made as a function of surface concentration exhibit maxima that\nare linked to the collapse of hydrophilic regions of the protein into the\nsubphase. Based on this data we present a configuration map of the protein\nconfiguration in the monolayer. These findings are supported by strain (surface\npressure) relaxation measurements and surface quasi-elastic light scattering\n(SQELS) measurements which suggest the existence of loops and tails in the\nsubphase at higher surface concentrations."
    },
    {
        "anchor": "Surfactant Mediated Particle Aggregation in Nonpolar Solvent: Aggregation behavior of particles in nonpolar medium is studied with\ntime-resolved light scattering. At low concentrations of surfactant particles\nare weakly charged and suspensions are not stable. Suspensions get\nprogressively more stable with increasing surfactant concentration as particles\nget more highly charged. At high concentrations the particles get neutralized\nand aggregation is again fast. The theory of Derjaguin, Landau, Verwey, and\nOverbeek (DLVO) is able to predict the stability ratios quantitatively by using\nthe experimentally measured surface charge, screening lengths and van der Waals\nforces.",
        "positive": "Mixed equilibrium/nonequilibrium effects govern surface mobility in\n  polymer glasses: The temperature at which supercooled liquids turn into solid-like glasses\n($T_g$) can change at the free surface, affecting the properties of\nnanostructured glasses and their applications. However, inadequate experimental\nresolution to determine the $T_g$ gradient and a longstanding debate over the\nrole of nonequilibrium effects have hindered fundamental understanding of this\nphenomenon. Using spatially resolved $T_g$ measurements and molecular dynamics\nsimulations, we reveal a crossover from equilibrium behavior to a new regime of\nnear-surface nonequilibrium glass physics on cooling. This crossover causes the\nform of the nonequilibrium $T_g$ gradient to change, highlighting the need to\ninclude these physics for rational understanding of the properties of realistic\nnanostructured glass-forming materials. They also potentially recast the\ninterpretation of decades of experimental data on nanoconfined glasses."
    },
    {
        "anchor": "Angular momentum exchange between coherent light and matter fields: Full, three dimensional, time-dependent simulations are presented\ndemonstrating the quantized transfer of angular momentum to a Bose-Einstein\ncondensate from a laser carrying orbital angular momentum in a\nLaguerre-Gaussian mode. The process is described in terms of coherent Bragg\nscattering of atoms from a chiral optical lattice. The transfer efficiency and\nthe angular momentum content of the output coupled vortex state are analyzed\nand compared with a recent experiment.",
        "positive": "Attraction-induced jamming in the flow of foam through a channel: We study the flow of a pressure-driven foam through a straight channel using\nnumerical simulations, and examine the effects of a tuneable attractive\npotential between bubbles. This potential, which accounts for the effects of\ndisjoining pressure in the liquid films between separating bubbles, is shown\nhere to introduce jamming and stick-slip flow in a straight channel. We report\non the behaviour of these new regimes by varying the strength of the attractive\npotential. It is seen that there is a force threshold below which the flow\njams, and on increasing the driving force, a cross over from intermittent\n(stick-slip) to smooth flow is observed. This threshold force below which the\nfoam jams increases linearly with the strength of the attractive potential. By\nexamining the spectra of energy fluctuations, we show that stick-slip flow is\ncharacterized by low frequency rearrangements and strongly local behaviour,\nwhereas steady flow shows a broad spectrum of energy drop events and collective\nbehaviour. Our work suggests that the stick-slip and the jamming regimes occur\ndue to the increased stabilization of contact networks by the attractive\npotential - as the strength of attraction is increased, bubbles are\nincreasingly trapped within networks, and there is a decrease in the number of\ncontact changes."
    },
    {
        "anchor": "Programming Curvature using Origami Tessellations: Origami describes rules for creating folded structures from patterns on a\nflat sheet, but does not prescribe how patterns can be designed to fit target\nshapes. Here, starting from the simplest periodic origami pattern that yields\none degree-of-freedom collapsible structures, we show that scale-independent\nelementary geometric constructions and constrained optimization algorithms can\nbe used to determine spatially modulated patterns that yield approximations to\ngiven surfaces of constant or varying curvature. Paper models confirm the\nfeasibility of our calculations. We also assess the difficulty of realizing\nthese geometric structures by quantifying the energetic barrier that separates\nthe metastable flat and folded states. Moreover, we characterize the trade-off\nbetween the accuracy to which the pattern conforms to the target surface, and\nthe effort associated with creating finer folds. Our approach enables the\ntailoring of origami patterns to drape complex surfaces independent of absolute\nscale, and quantify the energetic and material cost of doing so.",
        "positive": "Bacterial diffusion in disordered media, by forgetting the media: We study bacterial diffusion in disordered porous media. Interactions with\nobstacles, at unknown locations, make this problem challenging. We approach it\nby abstracting the environment to cell states with memoryless transitions. With\nthis, we derive an effective diffusivity that agrees well with simulations in\nexplicit geometries. The diffusivity is non-monotonic, and we solve the optimal\nrun length. We also find a rescaling that causes all of the theory and\nsimulations to collapse. Our results indicate that a small set of microscopic\nfeatures captures bacterial diffusion in disordered media."
    },
    {
        "anchor": "Inertio-elastic instability of non shear-banding wormlike micelles: Homogeneous polymer solutions are well-known to exhibit viscoelastic flow\ninstabilities: purely elastic when inertia is negligible, inertio-elastic\notherwise. Recently, shear-banding wormlike micelles solutions were also\ndiscovered to follow a similar phenomenology. In the shear-banding regime,\ninertia is usually negligible so only purely elastic flows have been reported.\nHere, we investigate a non-shear-banding solution where inertia becomes\nsignificant, leading to flow patterns akin to the inertio-elastic regime of\ndilute polymer solutions. We show that the instability follows a supercritical\nbifurcation and we investigate the structure of the inertio-elastic vortices\nthat develop above onset.",
        "positive": "Complex crystal structures formed by the self assembly of di-tethered\n  nanospheres: We report the results from a computational study of the self-assembly of\namphiphilic di-tethered nanospheres using molecular simulation. As a function\nof the interaction strength and directionality of the tether-tether\ninteractions, we predict the formation of four highly ordered phases not\npreviously reported for nanoparticle systems. We find a double diamond\nstructure comprised of a zincblende (binary diamond) arrangement of spherical\nmicelles with a complementary diamond network of nanoparticles (ZnS/D); a phase\nof alternating spherical micelles in a NaCl structure with a complementary\nsimple cubic network of nanoparticles to form an overall crystal structure\nidentical to that of AlCu_2Mn (NaCl/SC); an alternating tetragonal ordered\ncylinder phase with a tetragonal mesh of nanoparticles described by the [8,8,4]\nArchimedean tiling (TC/T); and an alternating diamond phase in which both\ndiamond networks are formed by the tethers (AD) within a nanoparticle matrix.\nWe compare these structures with those observed in linear and star triblock\ncopolymer systems."
    },
    {
        "anchor": "Growing spatial correlations of particle displacements in a simulated\n  liquid on cooling toward the glass transition: We define a correlation function that quantifies the spatial correlation of\nsingle-particle displacements in liquids and amorphous materials. We show for\nan equilibrium liquid that this function is related to fluctuations in a bulk\ndynamical variable. We evaluate this function using computer simulations of an\nequilibrium glass-forming liquid, and show that long range spatial correlations\nof displacements emerge and grow on cooling toward the mode coupling critical\ntemperature.",
        "positive": "Axisymmetric membranes with edges under external force: buckling,\n  minimal surfaces, and tethers: We use theory and numerical computation to determine the shape of an\naxisymmetric fluid membrane with a resistance to bending and constant area. The\nmembrane connects two rings in the classic geometry that produces a catenoidal\nshape in a soap film. In our problem, we find infinitely many branches of\nsolutions for the shape and external force as functions of the separation of\nthe rings, analogous to the infinite family of eigenmodes for the Euler\nbuckling of a slender rod. Special attention is paid to the catenoid, which\nemerges as the shape of maximal allowable separation when the area is less than\na critical area equal to the planar area enclosed by the two rings. A\nperturbation theory argument directly relates the tension of catenoidal\nmembranes to the stability of catenoidal soap films in this regime. When the\nmembrane area is larger than the critical area, we find additional cylindrical\ntether solutions to the shape equations at large ring separation, and that\narbitrarily large ring separations are possible. These results apply for the\ncase of vanishing Gaussian curvature modulus; when the Gaussian curvature\nmodulus is nonzero and the area is below the critical area, the force and the\nmembrane tension diverge as the ring separation approaches its maximum value.\nWe also examine the stability of our shapes and analytically show that\ncatenoidal membranes have markedly different stability properties than their\nsoap film counterparts."
    },
    {
        "anchor": "Light, Matter, Action: Shining light on active matter: Light carries energy and momentum. It can therefore alter the motion of\nobjects from atomic to astronomical scales. Being widely available, readily\ncontrollable and broadly biocompatible, light is also an ideal tool to propel\nmicroscopic particles, drive them out of thermodynamic equilibrium and make\nthem active. Thus, light-driven particles have become a recent focus of\nresearch in the field of soft active matter. In this perspective, we discuss\nrecent advances in the control of soft active matter with light, which has\nmainly been achieved using light intensity. We also highlight some first\nattempts to utilize light's additional degrees of freedom, such as its\nwavelength, polarization, and momentum. We then argue that fully exploiting\nlight with all of its properties will play a critical role to increase the\nlevel of control over the actuation of active matter as well as the flow of\nlight itself through it. This enabling step will advance the design of soft\nactive matter systems, their functionalities and their transfer towards\ntechnological applications.",
        "positive": "Wrinkling instability in 3D active nematics: In nature interactions between biopolymers and motor proteins give rise to\nbiologically essential emergent behaviours. Besides cytoskeleton mechanics,\nactive nematics arise from such interactions. Here we present a study on 3D\nactive nematics made of microtubules, kinesin motors and depleting agent. It\nshows a rich behaviour evolving from a nematically ordered space-filling\ndistribution of microtubule bundles toward a flattened and contracted 2D ribbon\nthat undergoes a wrinkling instability and subsequently transitions into a 3D\nactive turbulent state. The wrinkle wavelength is independent of the ATP\nconcentration and our theoretical model describes its relation with the\nappearance time. We compare the experimental results with a numerical\nsimulation that confirms the key role of kinesin motors in cross-linking and\nsliding the microtubules. Our results on the active contraction of the network\nand the independence of wrinkle wavelength on ATP concentration are important\nsteps forward for the understanding of these 3D systems."
    },
    {
        "anchor": "Effective surface shear viscosity of an incompressible particle-laden\n  fluid interface: The presence of even small amount of surfactant at the particle-laden fluid\ninterface subjected to shear makes surface flow incompressible if the shear\nrate is small enough [T. M. Fischer et al, J. Fluid Mech. 558, 451 (2006)]. In\nthe present paper the effective surface shear viscosity of a flat,\nlow-concentration, particle-laden incompressible interface separating two\nimmiscible fluids is calculated. The resulting value is found to be 7.6% larger\nthan the value obtained without account for surface incompressibility.",
        "positive": "Elastic effects of liquids on surface physics: The contact between a liquid and an elastic solid generates a stress vector\ndepending on the curvature tensor in each point of the separating surface. For\nnanometer values of the mean curvature and for suitable materials, the stress\nvector takes significant amplitude on the surface. Although the surface average\naction of the liquid on the solid is the hydrostatic pressure, the local strain\ngenerates torques tending to regularize the surface undulations and asperities."
    },
    {
        "anchor": "Determination of the electrical conductivity and the elctroosmotic\n  transfer in the concentrated dispersions on the basis of the cell theory of\n  the electroosmosis: Theoretical calculations of the electrical conductivity and electroosmotic\ntransfer as functions of the disperse phase volume fraction and non-dissolving\nboundary layer thickness were provided on the basis of the cell theory of\nelectroosmosis for the limiting case of large degree of electric double layers\noverlapping in interparticle space. The obtained results are in qualitative\nagreement with the experimental data and describe the main features of the\nlatter",
        "positive": "The Fourier state of a dilute granular gas described by the inelastic\n  Boltzmann equation: The existence of two stationary solutions of the nonlinear Boltzmann equation\nfor inelastic hard spheres or disks is investigated. They are restricted\nneither to weak dissipation nor to small gradients. The one-particle\ndistribution functions are assumed to have an scaling property, namely that all\nthe position dependence occurs through the density and the temperature. At the\nmacroscopic level, the state corresponding to both is characterized by uniform\npressure, no mass flow, and a linear temperature profile. Moreover, the state\nexhibits two peculiar features. First, there is a relationship between the\ninelasticity of collisions, the pressure, and the temperature gradient. Second,\nthe heat flux can be expressed as being linear in the temperature gradient,\ni.e. a Fourier-like law is obeyed. One of the solutions is singular in the\nelastic limit. The theoretical predictions following from the other one are\ncompared with molecular dynamics simulation results and a good agreement is\nobtained in the parameter region in which the Fourier state can be actually\nobserved in the simulations, namely not too strong inelasticity."
    },
    {
        "anchor": "Flow of Electrically Charged Fluids Through Elastic Porous Media: We study the flow of an electrically charged fluid through an elastic and\nporous medium. A three continuum model consisting of an elastic solid, a\nviscous fluid, and a mobile charge continuum is used. The relevant laws of\nphysics are applied systematically to the constituents or the combined\ncontinuum, leading to their continuity equations for conservation of mass or\ncharge, linear and angular momentum equations as well as constitutive\nrelations. The analysis assumes quasistatic electric fields and is for\nnonmagnetizable materials. The resulting theory is nonlinear, valid for large\ndeformations and strong fields and can be specialized or generalized in various\nways.",
        "positive": "Weak and Strong-Coupling Electrostatic Interactions between\n  Asymmetrically Charged Planar Surfaces: We compare weak and strong coupling theory of counterion-mediated\nelectrostatic interactions between two asymmetrically charged plates with\nextensive Monte-Carlo simulations. Analytical results in both weak and strong\ncoupling limits compare excellently with simulations in their respective\nregimes of validity. The system shows a surprisingly rich structure in terms of\ninteractions between the surfaces as well as fundamental qualitative\ndifferences in behavior in the weak and the strong coupling limits."
    },
    {
        "anchor": "Fracturing-induced fluidization of vibrated fine-powder column: We experimentally investigate the effect of vertical vibrations on the\nbrittle behavior of fine cohesive powders consisting of glass beads of 5\nmicrons in diameter. This is an attempt to understand the sole role of\nvibrations in fluidizing Geldart's group C powders, which is known for posing\ndifficulty while fluidization. We find that the cohesive powder column can be\ncompacted, fractured, and effectively fluidized by increasing the strengths of\nexternal vibrations. This process of vibration-induced fracturing is summarized\nin a full experimental phase diagram showing four distinct phases of the\nvibrated powder column: consolidation (CS), static fracture (SF), dynamic\nfracture (DF), and convective fracture (CF). We find that the boundary\nseparating the consolidated and fracture regimes depends on the dimensionless\nshaking strength, S. However, in the DF regime, the decompaction wave\npropagation speed normalized to gravitational speed is found to be independent\nof S. In order to reach our ultimate goal of effective fluidization of group C\npowders, we explore geometrical parameters like container shapes, sizes, and\nbase conditions. We find that the circular cylinder with hemispherical base\ncondition is the most effective container in order to achieve effective\nfluidization of group C powders when vibrated.",
        "positive": "Molecular hydrodynamics of the moving contact line in two-phase\n  immiscible flows: The ``no-slip'' boundary condition, i.e., zero fluid velocity relative to the\nsolid at the fluid-solid interface, has been very successful in describing many\nmacroscopic flows. A problem of principle arises when the no-slip boundary\ncondition is used to model the hydrodynamics of immiscible-fluid displacement\nin the vicinity of the moving contact line, where the interface separating two\nimmiscible fluids intersects the solid wall. Decades ago it was already known\nthat the moving contact line is incompatible with the no-slip boundary\ncondition, since the latter would imply infinite dissipation due to a\nnon-integrable singularity in the stress near the contact line. In this paper\nwe first present an introductory review of the problem. We then present a\ndetailed review of our recent results on the contact-line motion in immiscible\ntwo-phase flow, from MD simulations to continuum hydrodynamics calculations.\nThrough extensive MD studies and detailed analysis, we have uncovered the slip\nboundary condition governing the moving contact line, denoted the generalized\nNavier boundary condition. We have used this discovery to formulate a continuum\nhydrodynamic model whose predictions are in remarkable quantitative agreement\nwith the MD simulation results at the molecular level. These results serve to\naffirm the validity of the generalized Navier boundary condition, as well as to\nopen up the possibility of continuum hydrodynamic calculations of immiscible\nflows that are physically meaningful at the molecular level."
    },
    {
        "anchor": "Strong non-exponential relaxation and memory effects in a fluid with\n  non-linear drag: We analyse the dynamical evolution of a fluid with non-linear drag, for which\nbinary collisions are elastic, described at the kinetic level by the\nEnskog-Fokker-Planck equation. This model system, rooted in the theory of\nnon-linear Brownian motion, displays a really complex behaviour when quenched\nto low temperatures. Its glassy response is controlled by a long-lived\nnon-equilibrium state, independent of the degree of non-linearity and also of\nthe Brownian-Brownian collisions rate. The latter property entails that this\nbehaviour persists in the collisionless case, where the fluid is described by\nthe non-linear Fokker-Planck equation. The observed response, which includes\nnon-exponential, algebraic, relaxation and strong memory effects, presents\nscaling properties: the time evolution of the temperature -- for both\nrelaxation and memory effects -- falls onto a master curve, regardless of the\ndetails of the experiment. To account for the observed behaviour in\nsimulations, it is necessary to develop an extended Sonine approximation for\nthe kinetic equation -- which considers not only the fourth cumulant but also\nthe sixth one.",
        "positive": "Rigidity percolation control of the brittle-ductile transition in\n  disordered networks: In ordinary solids, material disorder is known to increase the size of the\nprocess zone in which stress concentrates at the crack tip, causing a\ntransition from localized to diffuse failure. Here, we report experiments on\ndisordered 2D lattices, derived from frictional particle packings, in which the\nmean coordination number $\\langle z \\rangle$ of the underlying network provides\na similar control. Our experiments show that tuning the connectivity of the\nnetwork provides access to a range of behaviors from brittle to ductile\nfailure. We elucidate the cooperative origins of this transition using a\nfrictional pebble game algorithm on the original, intact lattices. We find that\nthe transition corresponds to the isostatic value $\\langle z \\rangle = 3$ in\nthe large-friction limit, with brittle failure occurring for structures\nvertically spanned by a rigid cluster, and ductile failure for floppy networks\ncontaining nonspanning rigid clusters. Furthermore, we find that individual\nfailure events typically occur within the floppy regions separated by the rigid\nclusters."
    },
    {
        "anchor": "Minimum Entropy Production by Microswimmers with Internal Dissipation: The energy dissipation and entropy production by self-propelled microswimmers\ndiffer profoundly from passive particles pulled by external forces. The\ndifference extends both to the shape of the flow around the swimmer, as well as\nto the internal dissipation of the propulsion mechanism. Here we derive a\ngeneral theorem that provides an exact lower bound on the total, external and\ninternal, dissipation by a microswimmer. The problems that can be solved\ninclude an active surface-propelled droplet, swimmers with an extended\npropulsive layer and swimmers with an effective internal dissipation. We apply\nthe theorem to determine the swimmer shapes that minimize the total dissipation\nwhile keeping the volume constant. Our results show that the entropy production\nby active microswimmers is subject to different fundamental limits than the\nentropy production by externally driven particles.",
        "positive": "How to make and trap a pseudo-vesicle with a micropipette: We present a simple method to produce giant lipid pseudo-vesicles (vesicles\nwith an oily cap on the top), trapped in an agarose gel. The method can be\nimplemented using only a regular micropipette and relies on the formation of a\nwater/oil/water double droplet in liquid agarose. We characterize the produced\nvesicle with fluorescence imaging and establish the presence and integrity of\nthe lipid bilayer by the successful insertion of {\\alpha}-Hemolysin\ntransmembrane proteins. Finally, we show that the vesicle can be easily\nmechanically deformed, non-intrusively, by indenting the surface of the gel."
    },
    {
        "anchor": "Correlated hip motions during quiet standing: Kinematic measurements of two simultaneous coordinates from postural sway\nduring quiet standing were performed employing multiple ultrasonic transducers.\nThe use of accurate acoustic devices was required for the detection of the\nsmall random noise displacements. The trajectory in the anteroposterior -\nmediolateral plane of human chest was measured and compared with the trajectory\nin anteroposterior direction from the upper and lower body. The latter was\nstatistically analyzed and appeared to be strongly anti-correlated. The\nanti-correlations represent strong evidence for the dominance of hip strategy\nduring an unperturbed one minute stance. That the hip strategy, normally\nobserved for large amplitude motions, also appears in the small amplitude of a\nquite stance, indicates the utility of such noise measurements for exploring\nthe biomechanics of human balance.",
        "positive": "Picosecond Dynamic Heterogeneity, Hopping and Johari-Goldstein\n  Relaxation in Glassforming Liquids: We show that incoherent quasi-elastic neutron scattering (QENS) from\nmolecular liquids reveals a two-state dynamic heterogeneity on a 1 ps\ntimescale, where molecules are either highly confined or are free to undergo\nrelatively large excursions. Data ranging from deep in the glassy state to well\nabove the melting point allows us to observe temperature-dependent population\nlevels and exchange between these two states. A simple physical picture emerges\nfrom this data, combined with published work, that provides a mechanism for\n\"hopping\" and for the Johari-Goldstein ($\\beta_{JG}$) relaxation, and allows us\nto accurately calculate the diffusion coefficient, $D_T$, and characteristic\ntimes for $\\alpha$, and $\\beta_{JG}$ relaxations from ps timescale neutron\ndata."
    },
    {
        "anchor": "Curvature-Controlled Geometrical Lensing Behavior in Self-Propelled\n  Colloidal Particle Systems: In many biological systems, the curvature of the surfaces cells live on\ninfluence their collective properties. Curvature should likewise influence the\nbehavior of active colloidal particles. We show using molecular simulation of\nself-propelled active particles on surfaces of Gaussian curvature (both\npositive and negative) that curvature sign and magnitude can alter the system's\ncollective behavior. Curvature acts as a geometrical lens and shifts the\ncritical density of motility-induced phase separation (MIPS) to lower values\nfor positive curvature and higher values for negative curvature, which we\nexplain theoretically by the nature of parallel lines in spherical and\nhyperbolic space. Curvature also fluidizes dense MIPS clusters due to the\nemergence of defect patterns disrupting the crystalline order inside the\nclusters. Using our findings, we engineer three confining surfaces that\nstrategically combine regions of different curvature to produce a host of novel\ndynamic phases, including cyclic MIPS on sphercylinders, wave-like MIPS on\nspherocones, and cluster fluctuations on metaballs.",
        "positive": "Structural Signature of a Brittle-to-Ductile Transition in\n  Self-Assembled Networks: We study the nonlinear rheology of a novel class of transient networks, made\nof surfactant micelles of tunable morphology reversibly linked by block\ncopolymers. We couple rheology and time-resolved structural measurements, using\nsynchrotron radiation, to characterize the highly nonlinear viscoelastic\nregime. We propose the fluctuations of the degree of alignment of the micelles\nunder shear as a probe to identify a fracture process. We show a clear\nsignature of a brittle-to-ductile transition in transient gels, as the\nmorphology of the micelles varies, and provide a parallel between the fracture\nof solids and the fracture under shear of viscoelastic fluids."
    },
    {
        "anchor": "Collisions enhance tracer diffusivity in an active Janus bath: The generation of fluid flows by autophoretic microswimmers has been proposed\nas a mechanism to enhance mass transport at the micro- and nanoscale. Here, we\nexperimentally investigate the ability of model \"active baths\" of\nphotocatalytic silica-titania Janus microspheres to enhance the diffusivity of\ntracer particles at different microswimmer densities excluding collective\neffects. Inspired by the similarities between our experimental findings and\nprevious results for biological microorganisms, we also model our Janus\nmicroswimmers using a general squirmer framework. The numerical simulations\nfaithfully capture our observations, offer an insight into the microscopic\nmechanism underpinning tracer transport, and allow us to expand the parameter\nspace beyond our experimental system. We find strong evidence for a\ncollision-based mechanism for increased tracer diffusivity, which leads to the\nidentification of an operating window for enhanced tracer transport by chemical\nmicroswimmers based on dimensionless scaling arguments.",
        "positive": "Liquid demixing in elastic networks: cavitation, permeation, or size\n  selection?: Demixing of multicomponent biomolecular systems via liquid-liquid phase\nseparation (LLPS) has emerged as a potentially unifying mechanism governing the\nformation of several membrane-less intracellular organelles (\"condensates\"),\nboth in the cytoplasm (e.g., stress granules) and in the nucleoplasm (e.g.,\nnucleoli). While both in vivo experiments and studies of synthetic systems\ndemonstrate that LLPS is strongly affected by the presence of a macromolecular\nelastic network, a fundamental understanding of the role of such networks on\nLLPS is still lacking. Here we show that, upon accounting for capillary forces\nresponsible for network expulsion, small-scale heterogeneity of the network,\nand its nonlinear mechanical properties, an intriguing picture of LLPS emerges.\nSpecifically, we predict that, in addition to the experimentally observed\ncavitated droplets which fully exclude the network, two other phases are\nthermodynamically possible: elastically arrested, size-limited droplets at the\nnetwork pore scale, and network-including macroscopic droplets. In particular,\npore size-limited droplets may emerge in chromatin networks, with implications\nfor structure and function of nucleoplasmic condensates."
    },
    {
        "anchor": "Fluctuating viscoelasticity based on a finite number of dumbbells: Two alternative routes are taken to derive, on the basis of the dynamics of a\nfinite number of dumbbells, viscoelasticity in terms of a conformation tensor\nwith fluctuations. The first route is a direct approach using stochastic\ncalculus only, and it serves as a benchmark for the second route, which is\nguided by thermodynamic principles. In the latter, the Helmholtz free energy\nand a generalized relaxation tensor play a key role. It is shown that the\nresults of the two routes agree only if a finite-size contribution to the\nHelmholtz free energy of the conformation tensor is taken into account. Using\nstatistical mechanics, this finite-size contribution is derived explicitly in\nthis paper for a large class of models; this contribution is non-zero whenever\nthe number of dumbbells in the volume of observation is finite. It is noted\nthat the generalized relaxation tensor for the conformation tensor does not\nneed any finite-size correction.",
        "positive": "Liquid antiferromagnets in two dimensions: It is shown that, for proper symmetry of the parent lattice,\nantiferromagnetic order can survive in two-dimensional liquid crystals and even\nisotropic liquids of point-like particles, in contradiction to what common\nsense might suggest. We discuss the requirements for antiferromagnetic order in\nthe absence of translational and/or orientational lattice order. One example is\nthe honeycomb lattice, which upon melting can form a liquid crystal with\nquasi-long-range orientational and antiferromagnetic order but short-range\ntranslational order. The critical properties of such systems are discussed.\nFinally, we draw conjectures for the three-dimensional case."
    },
    {
        "anchor": "Deformation and break-up of viscoelastic droplets Using Lattice\n  Boltzmann Models: We investigate the break-up of Newtonian/viscoelastic droplets in a\nviscoelastic/Newtonian matrix under the hydrodynamic conditions of a confined\nshear flow. Our numerical approach is based on a combination of\nLattice-Boltzmann models (LBM) and Finite Difference (FD) schemes. LBM are used\nto model two immiscible fluids with variable viscosity ratio (i.e. the ratio of\nthe droplet to matrix viscosity); FD schemes are used to model viscoelasticity,\nand the kinetics of the polymers is introduced using constitutive equations for\nviscoelastic fluids with finitely extensible non-linear elastic dumbbells with\nPeterlin's closure (FENE-P). We study both strongly and weakly confined cases\nto highlight the role of matrix and droplet viscoelasticity in changing the\ndroplet dynamics after the startup of a shear flow. Simulations provide easy\naccess to quantities such as droplet deformation and orientation and will be\nused to quantitatively predict the critical Capillary number at which the\ndroplet breaks, the latter being strongly correlated to the formation of\nmultiple neckings at break-up. This study complements our previous\ninvestigation on the role of droplet viscoelasticity (A. Gupta \\& M.\nSbragaglia, {\\it Phys. Rev. E} {\\bf 90}, 023305 (2014)), and is here further\nextended to the case of matrix viscoelasticity.",
        "positive": "Theory of Cation Solvation and Ionic Association in Non-Aqueous Solvent\n  Mixtures: Conventional lithium-ion batteries, and many next-generation technologies,\nrely on organic electrolytes with multiple solvents to achieve the desired\nphysicochemical and interfacial properties. The complex interplay between these\nproperties can often be elucidated via the coordination environment of the\ncation. We develop a theory for the coordination shell of cations in\nnon-aqueous solvent mixtures that can be applied with high fidelity, up to\nsuper-concentrated electrolytes. Our theory can naturally explain simulation\nand experimental values of cation solvation in ''classical'' non-aqueous\nelectrolytes. Moreover, we utilise our theory to understand general design\nprinciples of emerging classes of non-aqueous electrolyte mixtures, such as\nhigh entropy electrolytes. It is hoped that this theory provides a systematic\nframework to understand simulations and experiments which engineer the\nsolvation structure and ionic associations of concentrated non-aqueous\nelectrolytes."
    },
    {
        "anchor": "Influence of mineralization and injection flow rate on flow patterns in\n  three-dimensional porous media: Reactive flows inside porous media play an important role in a number of\ngeophysical and industrial processes. Here we present three-dimensional\nexperimental measurements on how precipitation and flow patterns change with\nthe flow rate inside a model porous medium consisting of monodisperse glass\nbeads. The sample is initially filled with an aqueous solution of sodium\ncarbonate into which a solution of barium chloride is injected at a constant\nflow rate. Upon contact and reaction, the two reactants produce water-insoluble\nbarium carbonate which precipitates onto the glass beads. This precipitate then\nmodifies the flow morphology which in turn changes the spatial distribution of\nthe precipitate. We discuss the influence of the flow rate on the morphology of\nthe flow pattern and demonstrate that neither viscous fingering nor the\nRayleigh-Taylor instability have any significant influence in our model system.",
        "positive": "Harnessing elasticity to generate self-oscillation via an\n  electrohydrodynamic instability: Under a steady DC electric field of sufficient strength, a weakly conducting\ndielectric sphere in a dielectric solvent with higher conductivity can undergo\nspontaneous spinning (Quincke rotation) through a pitchfork bifurcation. We\ndesign an object composed of a dielectric sphere and an elastic filament. By\nsolving an elasto-electro-hydrodynamic (EEH) problem numerically, we uncover an\nEEH instability exhibiting diverse dynamic responses. Varying the bending\nstiffness of the filament, the composite object displays three behaviours: a\nstationary state, undulatory swimming and steady spinning, where the swimming\nresults from a self-oscillatory instability through a Hopf bifurcation. By\nconducting a linear stability analysis incorporating an elastohydrodynamic\nmodel, we theoretically predict the growth rates and critical conditions, which\nagree well with the numerical counterparts. We also propose a reduced model\nsystem consisting of a minimal elastic structure which reproduces the EEH\ninstability. The elasto-viscous response of the composite structure is able to\ntransform the pitchfork bifurcation into a Hopf bifurcation, leading to\nself-oscillation. Our results imply a new way of harnessing elastic media to\nengineer self-oscillations, and more generally, to manipulate and diversify the\nbifurcations and the corresponding instabilities. These ideas will be useful in\ndesigning soft, environmentally adaptive machines."
    },
    {
        "anchor": "Electric Switching of Fluorescence Decay in Gold-Silica-Dye Nematic\n  Nanocolloids Mediated by Surface Plasmons: Tunable composite materials with interesting physical behavior can be\ndesigned through integrating unique optical properties of solid nanostructures\nwith the facile responses of soft matter to weak external stimuli, but this\napproach remains challenged by their poorly controlled co-assembly at the\nmesoscale. Using scalable wet chemical synthesis procedures, we fabricated\nanisotropic gold-silica-dye colloidal nanostructures and then organized them\ninto the device-scale (demonstrated for square inch cells) electrically tunable\ncomposites by simultaneously invoking molecular and colloidal self-assembly. We\nshow that the ensuing ordered colloidal dispersions of shape-anisotropic\nnanostructures exhibit tunable fluorescence decay rates and intensity. We\ncharacterize how these properties depend on low-voltage fields and polarization\nof both the excitation and emission light, demonstrating a great potential for\nthe practical realization of an interesting breed of nanostructured composite\nmaterials.",
        "positive": "Segmental Lennard-Jones Interactions for Semi-flexible Polymer Networks: Simulating soft matter systems such as the cytoskeleton can enable deep\nunderstanding of experimentally observed phenomena. One challenge of modeling\nsuch systems is realistic description of the steric repulsion between nearby\npolymers. Previous models of the polymeric excluded volume interaction have the\ndeficit of being non-analytic, being computationally expensive, or allowing\npolymers to erroneously cross each other. A recent solution to these issues,\nimplemented in the MEDYAN simulation platform, uses analytical expressions\nobtained from integrating an interaction kernel along the lengths of two\npolymer segments to describe their repulsion. Here, we extend this model by\nre-deriving it for lower-dimensional geometrical configurations, deriving\nsimilar expressions using a steeper interaction kernel, comparing it to other\ncommonly used potentials, and showing how to parameterize these models. We also\ngeneralize this new integrated style of potential by introducing a segmental\nLennard-Jones potential, which enables modelling both attractive and repulsive\ninteractions in semi-flexible polymer networks. These results can be further\ngeneralized to facilitate the development of effective interaction potentials\nfor other finite elements in simulations of soft-matter systems."
    },
    {
        "anchor": "Theory of molecular crowding in Brownian hard-sphere liquids with\n  application to the polymer coil-globule transition: We derive an analytical pair potential of mean force for Brownian molecules\nin the liquid-state. Our approach accounts for many-particle correlations of\ncrowding particles of the liquid, and for diffusive transport across the\nspatially modulated local density of crowders in the dense environment.\nSpecializing on the limit of equal-size particles, we show that this diffusive\ntransport leads to additional density- and structure-dependent terms in the\ninteraction potential, and to a much stronger attraction (by a factor ~4 at\naverage volume fraction of crowders 0.25) than in the standard depletion\ninteraction where the diffusive effects are neglected. As an illustration of\nthe theory, we use it to study the size of a polymer chain in a solution of\ninert crowders. Even in the case of athermal background solvent, when a\nclassical chain should be fully swollen, we find a sharp coil-globule\ntransition of the ideal chain collapsing at a critical value of the crowder\nvolume fraction ~0.145.",
        "positive": "Self-motile colloidal particles: from directed propulsion to random walk: The motion of an artificial micro-scale swimmer that uses a chemical reaction\ncatalyzed on its own surface to achieve autonomous propulsion is fully\ncharacterized experimentally. It is shown that at short times, it has a\nsubstantial component of directed motion, with a velocity that depends on the\nconcentration of fuel molecules. At longer times, the motion reverts to a\nrandom walk with a substantially enhanced diffusion coefficient. Our results\nsuggest strategies for designing artificial chemotactic systems."
    },
    {
        "anchor": "A Unifying Model for the Rheological Behavior of Hygro-responsive\n  Materials: Hygro-responsive materials exhibit a complex structure-to-property\nrelationship. The interactions of water within these materials under varying\nhygric and mechanical loads play a crucial role in their macroscopic\ndeformation and final application. While multiple models are available in\nliterature, many lack a comprehensive physical understanding of these\nphenomena. In this study, we introduce a novel Stick-Slip Fiber Bundle Model\nthat captures the fundamental behaviors of hygro-responsive materials. We\nincorporate moisture-dependent elements and rules governing the initiation and\nrelaxation of slip strains as well as failure to the statistical approach\noffered by Fiber Bundle Models. The additional features are based on\nwell-founded interpretations of the structure-to-property relationship in\ncellulosic materials. Slip strains are triggered by changes in load and\nmoisture, as well as by creep deformations. When subjected to moisture cycles,\nthe model accumulates slip strains, resulting in mechanosorptive behavior. When\nthe load is removed, slip strains are partially relaxed, and subsequent\nmoisture cycles trigger further relaxation, as expected from observations with\nmechanosorptive material. Importantly, these slip strains are not considered\nplastic strains; instead, they are unified, non-linear frozen strains,\nactivated by various stimuli. Failure of fibers is defined by a critical number\nof slip events allowing for an integrated simulation from intact, via damaged,\nfailed states. We investigate the transition between these regimes upon changes\nin the hygric and mechanical loading history for relevant parameter ranges. Our\nenhanced Stick-Slip Fiber Bundle Model increases the understanding of the\nintricate behavior of hygro-responsive materials and contributes to a more\nrobust framework for analyzing and interpreting their properties.",
        "positive": "A Ubiquitous Thermal Conductivity Formula for Liquids, Polymer Glass,\n  and Amorphous Solids: The microscopic mechanism of thermal transport in liquids and amorphous\nsolids has been an outstanding problem for a long time. There have been several\ndifferent approaches to explain the thermal conductivities for these systems,\nfor example, the Bridgman's formula for simple liquids, the concept of the\nminimum thermal conductivity for amorphous solids, and the thermal resistance\nnetwork model for amorphous polymers. Here, we present a ubiquitous formula to\nexplain the thermal conductivities of liquids and amorphous solids in a unified\nway. The calculated thermal conductivities using this formula without fitting\nparameters are in excellent agreement with the experimental data for these\nsystems. Our formula is not only providing detailed implications on microscopic\nmechanisms of heat transfer in these systems, but also solves the discrepancies\nbetween existing formulae and experimental data."
    },
    {
        "anchor": "Quantification and Physics of Cold Plasma Treatment of Organic Liquid\n  Surfaces: Plasma treatment increases the surface energy of condensed phases: solids and\nliquids. Two independent methods of the quantification of the influence imposed\nby a cold radiofrequency air plasma treatment on the surface properties of\nsilicone oils (polydimethylsiloxane) of various molecular masses and castor oil\nare introduced. Under the first method the water droplet coated by oils was\nexposed to the cold air radiofrequency plasma, resulting in an increase of\noil/air surface energy. An expression relating the oil/air surface energy to\nthe apparent contact angle of the water droplet coated with oil was derived.\nThe apparent contact angle was established experimentally. Calculation of the\noil/air surface energy and spreading parameter was carried out for the various\nplasma-treated silicone and castor oils. The second method is based on the\nmeasurement of the electret response of the plasma-treated liquids.",
        "positive": "Effective Cahn-Hilliard equation for the phase separation of active\n  Brownian particles: The kinetic separation of repulsive active Brownian particles into a dense\nand a dilute phase is analyzed using a systematic coarse-graining strategy. We\nderive an effective Cahn-Hilliard equation on large length and time scales,\nwhich implies that the separation process can be mapped onto that of passive\nparticles. A lower density threshold for clustering is found, and using our\napproach we demonstrate that clustering first proceeds via a hysteretic\nnucleation scenario and above a higher threshold changes into a spinodal-like\ninstability. Our results are in agreement with particle-resolved computer\nsimulations and can be verified in experiments of artificial or biological\nmicroswimmers."
    },
    {
        "anchor": "First Jump of Microgel: Actuation Speed Enhancement by Elastic\n  Instability: Swelling-induced snap-buckling in a 3D micro hydrogel device, inspired by the\ninsect-trapping action of Venus flytrap, makes it possible to generate\nastonishingly fast actuation. We demonstrate that elastic energy is effectively\nstored and quickly released from the device by incorporating elastic\ninstability. Utilizing its rapid actuation speed, the device can even jump by\nitself upon wetting.",
        "positive": "Molecular Dynamics Simulation of Vascular Network Formation: Endothelial cells are responsible for the formation of the capillary blood\nvessel network. We describe a system of endothelial cells by means of\ntwo-dimensional molecular dynamics simulations of point-like particles. Cells'\nmotion is governed by the gradient of the concentration of a chemical substance\nthat they produce (chemotaxis). The typical time of degradation of the chemical\nsubstance introduces a characteristic length in the system. We show that\npoint-like model cells form network resembling structures tuned by this\ncharacteristic length, before collapsing altogether. Successively, we improve\nthe non-realistic point-like model cells by introducing an isotropic strong\nrepulsive force between them and a velocity dependent force mimicking the\nobserved peculiarity of endothelial cells to preserve the direction of their\nmotion (persistence). This more realistic model does not show a clear network\nformation. We ascribe this partial fault in reproducing the experiments to the\nstatic geometry of our model cells that, in reality, change their shapes by\nelongating toward neighboring cells."
    },
    {
        "anchor": "Linear Polycatenanes from Kinetoplast Edge Loops: We use graph theory simulations and single molecule experiments to\ninvestigate percolation properties of kinetoplasts, the topologically linked\nmitochondrial DNA from trypanosome parasites. The edges of some kinetoplast\nnetworks contain a fiber of redundantly catenated DNA loops, but previous\ninvestigations of kinetoplast topology did not take this into account. Our\ngraph simulations track the size of connected components in lattices as nodes\nare removed, analogous to the removal of minicircles from kinetoplasts. We find\nthat when the edge loop is taken into account, the largest component after the\nnetwork de-percolates is a remnant of the edge loop, before it undergoes a\nsecond percolation transition and breaks apart. This implies that\nstochastically removing minicircles from kinetoplast DNA would isolate large\npolycatenanes, which is observed in experiments that use photonicking to\nstochastically destroy kinetoplasts from Crithidia fasciculata. Our results\nimply kinetoplasts may be used as a source of linear polycatenanes for future\nexperiments.",
        "positive": "Structural and electrostatic properties between pH-responsive\n  polyelectrolyte brushes studied by augmented strong stretching theory: In this paper, we study electrostatic and structural properties between\npH-responsive polyelectrolyte brushes by using a strong stretching theory\naccounting for excluded volume interactions, the density of polyelectrolyte\nchargeable sites and the Born energy difference between the inside and outside\nof the brush layer.\n  In a free energy framework, we obtain self-consistent field equations to\ndetermine electrostatic properties between two pH-responsive polyelectrolyte\nbrushes. We elucidate that in the region between two pH-responsive\npolyelectrolyte brushes, electrostatic potential at the centerline and osmotic\npressure increase not only with excluded volume interaction, but also with\ndensity of chargeable sites on a polyelectrolyte molecule.\n  Importantly, we clarify that when two pH-responsive polyelectrolyte brushes\napproach each other, the brush thickness becomes short and that a large\nexcluded volume interaction and a large density of chargeable sites yield the\nenhanced contract of polyelectrolyte brushes. In addition, we also demonstrate\nhow the influence of such quantities as pH, the number of Kuhn monomers, the\ndensity of charged sites, the lateral separation between adjacent\npolyelectrolyte brushes, Kuhn length on the electrostatic and structural\nproperties between the two polyelectrolyte brushes is affected by the exclusion\nvolume interaction.\n  Finally, we investigate the influence of Born energy difference on the\nthickness of polyelectrolyte brushes and the osmotic pressure between two\npH-responsive polyelectrolyte brushes."
    },
    {
        "anchor": "A universality class for RNA-like polymers and double polymers: We examine the statistics of conformations of a linear polymer in a solvent.\nThe polymer is allowed to form double polymers. We closely follow a classical\ntechnique to derive a field theory for the problem from an $O\\left(n\\right)$\nsymmetric spin model. The field theory is a model for RNA or DNA with constant\nbinding energy per monomer.\n  It is shown that there is a stable renormalization group fixed point, at\nwhich the double polymer decouples from the single-strand polymer and becomes a\nbranched polymer of the conventional type with a three-point interaction. To\nreach this fixed point, at least one parameter must be adjusted. The critical\ndimension is eight. Fisher-renormalization, equation of state and critical\nexponents are reproduced in this limit. The single-strand polymer depends on\nthe double-strand polymer and disappears at the critical point, but has its own\ncritical exponents.",
        "positive": "Static and dynamic contributions to anomalous chain dynamics in polymer\n  blends: By means of computer simulations, we investigate the relaxation of the Rouse\nmodes in a simple bead-spring model for non-entangled polymer blends. Two\ndifferent models are used for the fast component, namely fully-flexible and\nsemiflexible chains. The latter are semiflexible in the meaning that static\nintrachain correlations are strongly non-gaussian at all length scales. The\ndynamic asymmetry in the blend is strongly enhanced by decreasing temperature,\ninducing confinement effects on the fast component. The dynamics of the Rouse\nmodes show very different trends for the two models of the fast component. For\nthe fully-flexible case, the relaxation times exhibit a progressive deviation\nfrom Rouse scaling on increasing the dynamic asymmetry. This anomalous effect\nhas a dynamic origin. It is not related to particular static features of the\nRouse modes, which indeed are identical to those of the fully-flexible\nhomopolymer, and are not modified by the dynamic asymmetry in the blend. On the\ncontrary, in the semiflexible case the relaxation times exhibit approximately\nthe same scaling behaviour as the amplitudes of the modes. This suggests that\nthe origin of the anomalous dynamic scaling for semiflexible chains confined in\nthe blend is esentially of static nature. We discuss implications of these\nobservations for the applicability of theoretical approaches to chain dynamics\nin polymer blends."
    },
    {
        "anchor": "The Effects of the Interplay Between Motor and Brownian Forces on the\n  Rheology of Active Gels: Active gels perform key mechanical roles inside the cell, such as cell\ndivision, motion and force sensing. The unique mechanical properties required\nto perform such functions arise from the interactions between molecular motors\nand semi-flexible polymeric filaments. Molecular motors can convert the energy\nreleased in the hydrolysis of ATP into forces of up to pico-Newton magnitudes.\nMoreover, the polymeric filaments that form active gels are flexible enough to\nrespond to Brownian forces, but also stiff enough to support the large tensions\ninduced by the motor-generated forces. Brownian forces are expected to have a\nsignificant effect especially at motor activities at which stable\nnon-contractile in vitro active gels are prepared for rheological measurements.\nHere, a microscopic mean-field theory of active gels originally formulated in\nthe limit of motor-dominated dynamics is extended to include Brownian forces.\nIn the model presented here Brownian forces are included accurately, at real\nroom temperature, even in systems with high motor activity. It is shown that a\nsubtle interplay, or competition, between motor-generated forces and Brownian\nforces has an important impact in the mass transport and rheological properties\nof active gels. The model predictions show that at low frequencies the dynamic\nmodulus of active gels is determined mostly by motor protein dynamics. However,\nBrownian forces significantly increase the breadth of the relaxation spectrum\nand can affect the shape of the dynamic modulus over a wide frequency range\neven for ratios of motor to Brownian forces of more than a hundred. Since the\nratio between motor and Brownian forces is sensitive to ATP concentration, the\nresults presented here shed some light on how the transient mechanical response\nof active gels changes with varying ATP concentration.",
        "positive": "Experimental evidence of shock mitigation in a Hertzian tapered chain: We present an experimental study of the mechanical impulse propagation\nthrough a horizontal alignment of elastic spheres of progressively decreasing\ndiameter $\\phi_n$, namely a tapered chain. Experimentally, the diameters of\nspheres which interact via the Hertz potential are selected to keep as close as\npossible to an exponential decrease, $\\phi_{n+1}=(1-q)\\phi_n$, where the\nexperimental tapering factor is either $q_1\\simeq5.60$~% or $q_2\\simeq8.27$~%.\nIn agreement with recent numerical results, an impulse initiated in a\nmonodisperse chain (a chain of identical beads) propagates without shape\nchanges, and progressively transfer its energy and momentum to a propagating\ntail when it further travels in a tapered chain. As a result, the front pulse\nof this wave decreases in amplitude and accelerates. Both effects are\nsatisfactorily described by the hard spheres approximation, and basically, the\nshock mitigation is due to partial transmissions, from one bead to the next, of\nmomentum and energy of the front pulse. In addition when small dissipation is\nincluded, a better agreement with experiments is found. A close analysis of the\nloading part of the experimental pulses demonstrates that the front wave adopts\nitself a self similar solution as it propagates in the tapered chain. Finally,\nour results corroborate the capability of these chains to thermalize\npropagating impulses and thereby act as shock absorbing devices."
    },
    {
        "anchor": "Correlations of plasticity in sheared glasses: In a recent paper [S. Mandal et al., Phys. Rev. E 88, 022129 (2013)] the\nnature of spatial correlations of plasticity in hard sphere glasses was\naddressed both via computer simulations and in experiments. It was found that\nthe experimentally obtained correlations obey a power law whereas the\ncorrelations from simulations are better fitted by an exponential decay. We\nhere provide direct evidence--- via simulations of a hard sphere glass in\n2D---that this discrepancy is a consequence of the finite system size in the 3D\nsimulations. By extending the study to a 2D soft disk model at zero\ntemperature, the robustness of the power-law decay in sheared amorphous solids\nis underlined. Deviations from a power law occur when either reducing the\npacking fraction towards the supercooled regime in the case of hard spheres or\nchanging the dissipation mechanism from contact dissipation to a mean-field\ntype drag for the case of soft disks.",
        "positive": "Ab initio calculation of the KRb dipole moments: The relativistic configuration interaction valence bond method has been used\nto calculate permanent and transition electric dipole moments of the KRb\nheteronuclear molecule as a function of internuclear separation. The permanent\ndipole moment of the ground state $X^1\\Sigma^+$ potential is found to be\n0.30(2) $ea_0$ at the equilibrium internuclear separation with excess negative\ncharge on the potassium atom. For the $a^3\\Sigma^+$ potential the dipole moment\nis an order of magnitude smaller (1 $ea_0=8.47835 10^{-30}$ Cm) In addition, we\ncalculate transition dipole moments between the two ground-state and\nexcited-state potentials that dissociate to the K(4s)+Rb(5p) limits. Using this\ndata we propose a way to produce singlet $X^1\\Sigma^+$ KRb molecules by a\ntwo-photon Raman process starting from an ultracold mixture of doubly\nspin-polarized ground state K and Rb atoms. This Raman process is only allowed\ndue to relativistic spin-orbit couplings and the absence of gerade/ungerade\nselection rules in heteronuclear dimers."
    },
    {
        "anchor": "Effective pair interactions between colloidal particles at a\n  nematic-isotropic interface: The Landau-de Gennes free energy is used to study theoretically the\ninteraction of parallel cylindrical colloidal particles trapped at a\nnematic-isotropic interface. We find that the effective interaction potential\nis non-monotonic. The corresponding force-distance curves exhibit jumps and\nhysteresis upon approach/separation due to the creation/annihilation of\ntopological defects. Minimization results suggest a simple empirical pair\npotential for the effective colloid-colloid interaction at the interface. We\npropose that the interface-mediated interaction can play an important role in\nself-organization and clustering of colloidal particles at such interfaces.",
        "positive": "Electric Field and Humidity Trigger Contact Electrification: Here, we study the old problem of why identical insulators can charge one\nanother on contact. We perform several experiments showing that, if driven by a\npreexisting electric field, charge is transferred between contacting\ninsulators. This happens because the insulator surfaces adsorb small amounts of\nwater from a humid atmosphere. We believe the electric field then separates\npositively from negatively charged ions prevailing within the water, which we\nbelieve to be hydronium and hydroxide ions, such that at the point of contact,\npositive ions of one insulator neutralize negative ions of the other one,\ncharging both of them. This mechanism can explain for the first time the\nobservation made four decades ago that wind-blown sand discharges in sparks if\nand only if a thunderstorm is nearby."
    },
    {
        "anchor": "Dynamics of folding in Semiflexible filaments: We investigate the dynamics of a single semiflexible filament, under the\naction of a compressing force, using numerical simulations and scaling\narguments. The force is applied along the end to end vector at one extremity of\nthe filament, while the other end is held fixed. We find that, unlike in\nelastic rods the filament folds asymmetrically with a folding length which\ndepends only on the bending stiffness and the applied force. It is shown that\nthis behavior can be attributed to the exponentially falling tension profile in\nthe filament. While the folding time depends on the initial configuration, at\nlate time, the distance moved by the terminal point of the filament and the\nlength of the fold shows a power law dependence on time with an exponent 1/2.",
        "positive": "Microscopic modeling of contact formation between confined surfaces in\n  solution: We derive a Kinetic Monte Carlo model for studying how contacts form between\nconfined surfaces in an ideal solution. The model incorporates repulsive and\nattractive surface-surface forces between a periodic (2+1)-dimensional\nsolid-on-solid (SOS) crystal surface and a confining flat surface. The\nrepulsive interaction is derived from the theory of electric double-layers, and\nthe attractive interactions are Van der Waals interactions between particles on\nthe SOS surface and the confining surface. The confinement is induced by a\nconstant external pressure normal to the surfaces which is in mechanical\nequilibrium with the surface-surface forces. The system is in thermal\nequilibrium, and particles can deposit to and dissolve from the SOS surface.\nThe size of stable contacts formed between the surfaces in chemical equilibrium\nshow a non-trivial dependency on the external pressure which is\nphenomenologically similar to the dependency of oscillatory hydration forces on\nthe surface-surface separation. As contacts form we find classical phenomena\nsuch as Ostwald ripening, coalescence, and primary and secondary nucleation\nstages. We find contacts shaped as islands, bands or pits, depending solely on\nthe contact size relative to the system size. We also find the model to behave\nwell out of chemical equilibrium. The model is relevant for understanding\nprocesses where the force of crystallization and pressure solution are key\nmechanisms."
    },
    {
        "anchor": "Phase behavior and structure of colloidal bowl-shaped particles:\n  simulations: We study the phase behavior of bowl-shaped particles using computer\nsimulations. These particles were found experimentally to form a meta-stable\nworm-like fluid phase in which the bowl-shaped particles have a strong tendency\nto stack on top of each other [M.Marechal et al, Nano Letters 10, 1907 (2010)].\nIn this work, we show that the transition from the low-density fluid to the\nworm-like phase has an interesting effect on the equation of state. The\nsimulation results also show that the worm-like fluid phase transforms\nspontaneously into a columnar phase for bowls that are sufficiently deep.\nFurthermore, we describe the phase behavior as obtained from free energy\ncalculations employing Monte Carlo simulations. The columnar phase is stable\nfor bowl shapes ranging from infinitely thin bowls to surprisingly shallow\nbowls. Aside from a large region of stability for the columnar phase, the phase\ndiagram features four novel crystal phases and a region where the stable fluid\ncontains worm-like stacks.",
        "positive": "Binding of Similarly Charged Plates: A Global Analysis: Similarly and highly charged plates in the presence of multivalent counter\nions attract each other, leading to electrostatically bound states. Using\nMonte-Carlo simulations we obtain the inter-plate pressure in the global\nparameter space. The equilibrium plate separation, where the pressure changes\nfrom attractive to repulsive, exhibits a novel unbinding transition. A\nsystematic and asymptotically exact strong-coupling field-theory yields the\nbound state from a competition between counter-ion entropy and electrostatic\nattraction, in agreement with simple scaling arguments."
    },
    {
        "anchor": "Active Brownian motion of emulsion droplets: Coarsening dynamics at the\n  interface and rotational diffusion: A micron-sized droplet of bromine water immersed in a surfactant-laden oil\nphase can swim (S. Thutupalli, R. Seemann, S. Herminghaus, New J. Phys. 13\n073021 (2011)). The bromine reacts with the surfactant at the droplet interface\nand generates a surfactant mixture. It can spontaneously phase-separate due to\nsolutocapillary Marangoni flow, which propels the droplet. We model the system\nby a diffusion-advection-reaction equation for the mixture order parameter at\nthe interface including thermal noise and couple it to fluid flow. Going beyond\nprevious work, we illustrate the coarsening dynamics of the surfactant mixture\ntowards phase separation in the axisymmetric swimming state. Coarsening\nproceeds in two steps: an initially slow growth of domain size followed by a\nnearly ballistic regime. On larger time scales thermal fluctuations in the\nlocal surfactant composition initiates random changes in the swimming direction\nand the droplet performs a persistent random walk, as observed in experiments.\nNumerical solutions show that the rotational correlation time scales with the\nsquare of the inverse noise strength. We confirm this scaling by a perturbation\ntheory for the fluctuations in the mixture order parameter and thereby identify\nthe active emulsion droplet as an active Brownian particle.",
        "positive": "Electronic and vibronic properties of a discotic liquid-crystal and its\n  charge transfer complex: Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine\nvisible light absorption and rapid charge transfer characteristics within the\nCT complex, being favorable properties for photovoltaic (PV) applications. We\npresent a detailed study of the electronic and vibrational properties of the\nprototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene\n(HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular\ncharge transfer occurs in the groundstate of the complex: a charge\ndelocalization of about 10-2 electron from the HAT6 core to TNF is deduced from\nboth Raman and our previous NMR measurements (Reference 32), implying the\npresence of permanent dipoles at the donor-acceptor interface. A combined\nanalysis of density functional theory calculations, resonant Raman and UV-VIS\nabsorption measurements indicate that fast relaxation occurs in the UV region\ndue to intramolecular vibronic coupling of HAT6 quinoidal modes with lower\nlying electronic states. Relatively slower relaxation in the visible region\nCT-band of the complex is also indicated, which likely involves motions of the\nTNF nitro groups. The fast quinoidal relaxation process in the hot UV band of\nHAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit,\nsuggesting that the underlying vibronic coupling mechanism can be generic for\npolyaromatic hydrocarbons. Both the presence of CT dipoles and relatively slow\nrelaxation processes in the CT band can be relevant concerning the design of\nDLC based organic PV systems."
    },
    {
        "anchor": "Understanding the Onset of Oscillatory Swimming in Microchannels: Self-propelled colloids (swimmers) in confining geometries follow\ntrajectories determined by hydrodynamic interactions with the bounding\nsurfaces. However, typically these interactions are ignored or truncated to\nlowest order. We demonstrate that higher-order hydrodynamic moments cause\nrod-like swimmers to follow oscillatory trajectories in quiescent fluid between\ntwo parallel plates, using a combination of lattice-Boltzmann simulations and\nfar-field calculations. This behavior occurs even far from the confining walls\nand does not require lubrication results. We show that a swimmer's hydrodynamic\nquadrupole moment is crucial to the onset of the oscillatory trajectories. This\ninsight allows us to develop a simple model for the dynamics near the channel\ncenter based on these higher hydrodynamic moments, and suggests opportunities\nfor trajectory-based experimental characterization of swimmers' hydrodynamic\nproperties.",
        "positive": "Controlled Capillary Assembly of Magnetic Janus Particles at Fluid-Fluid\n  Interfaces: Capillary interactions can be used to direct assembly of particles adsorbed\nat fluid-fluid interfaces. Precisely controlling the magnitude and direction of\ncapillary interactions to assemble particles into favoured structures for\nmaterials science purposes is desirable but challenging. In this paper, we\ninvestigate capillary interactions between magnetic Janus particles adsorbed at\nfluid-fluid interfaces. We develop a pair-interaction model that predicts that\nthese particles should arrange into a side--side configuration, and carry out\nsimulations that confirm the predictions of our model. Finally, we investigate\nthe monolayer structures that form when many magnetic Janus particles adsorb at\nthe interface. We find that the particles arrange into long, straight chains\nexhibiting little curvature, in contrast with capillary interactions between\nellipsoidal particles. We further find a regime in which highly ordered,\nlattice-like monolayer structures form, which can be tuned dynamically using an\nexternal magnetic field."
    },
    {
        "anchor": "Universal amplitudes of the Casimir-like interactions between four types\n  of rods in fluid membranes: The fluctuation-induced, Casimir-like interaction between two parallel rods\nof length L adsorbed on a fluid membrane is calculated analytically at short\nseparations d<<L. The rods are modeled as constraints imposed on the membrane\ncurvature along a straight line. This allows to define four types of rods,\naccording to whether the membrane can twist along the rod and/or curve across\nit. For stiff constraints, all the interaction potentials between the different\ntypes of rods are attractive and proportional to L/d. Two of the four types of\nrods are then equivalent, which yields six universal Casimir amplitudes.\nRepulsion can occur between different rods for soft constraints. Numerical\nresults obtained for all ranges of d/L show that the attraction potential\nreaches kT for d/L\\simeq0.2. At separations smaller than d_c \\approx\nL(L/l_p)^(1/3), where l_p is the rod persistence length, two rods with fixed\nends will bend toward each other and finally come into contact because of the\nCasimir interaction.",
        "positive": "Are nucleation bubbles in a liquid all independent?: The spontaneous formation of tiny bubbles in a liquid is at the root of the\nnucleation mechanism during the liquid-to-vapor transition of a metastable\nliquid. The smaller the bubbles the larger their probability to appear, and\neven for moderately metastable liquid, it is frequent to observe several tiny\nbubbles close to each other, suggesting that they are not all independent. It\nis shown that these spatially correlated bubbles should be seen as belonging to\none single density depression of the liquid due to fluctuations (called LDR for\nLow Density Region) and should be counted as one event instead of several. This\nhas a major impact on the characterization of the bubble density in a liquid,\nwith consequences (i) for understanding liquid-to-vapor transitions which\nproceed through growing and merging of these correlated bubbles, and (ii) for\nfree energy profile and barrier calculations with molecular simulation\ntechniques which require to convert the calculated size distribution of the\nlargest bubble into the size distribution of any bubble. Remarkably, the\naverage number of LDRs in a given volume simply relates to the probability of\nnot having bubbles in the liquid."
    },
    {
        "anchor": "Structure factors in granular experiments with homogeneous fluidization: Velocity and density structure factors are measured over a hydrodynamic range\nof scales in a horizontal quasi-2d fluidized granular experiment, with packing\nfractions $\\phi\\in[10%,40%]$. The fluidization is realized by vertically\nvibrating a rough plate, on top of which particles perform a Brownian-like\nhorizontal motion in addition to inelastic collisions. On one hand, the density\nstructure factor is equal to that of elastic hard spheres, except in the limit\nof large length-scales, as it occurs in the presence of an effective\ninteraction. On the other hand, the velocity field shows a more complex\nstructure which is a genuine expression of a non-equilibrium steady state and\nwhich can be compared to a recent fluctuating hydrodynamic theory with\nnon-equilibrium noise. The temporal decay of velocity modes autocorrelations is\ncompatible with linear hydrodynamic equations with rates dictated by viscous\nmomentum diffusion, corrected by a typical interaction time with the\nthermostat. Equal-time velocity structure factors display a peculiar shape with\na plateau at large length-scales and another one at small scales, marking two\ndifferent temperatures: the \"bath\" temperature $T_b$, depending on shaking\nparameters, and the \"granular\" temperature $T_g<T_b$, which is affected by\ncollisions. The two ranges of scales are separated by a correlation length\nwhich grows with $\\phi$, after proper rescaling with the mean free path.",
        "positive": "Tailoring of phononic band structures in colloidal crystals: We report an experimental study of the elastic properties of a\ntwo-dimensional (2D) colloidal crystal subjected to light-induced substrate\npotentials. In agreement with recent theoretical predictions [H.H. von\nGruenberg and J. Baumgartl, Phys. Rev. E 75, 051406 (2007)] the phonon band\nstructure of such systems can be tuned depending on the symmetry and depth of\nthe substrate potential. Calculations with binary crystals suggest that\nphononic band engineering can be also performed by variations of the pair\npotential and thus opens novel perspectives for the fabrication of phononic\ncrystals with band gaps tunable by external fields."
    },
    {
        "anchor": "Topological and geometrical disorder correlate robustly in\n  two-dimensional foams: A 2D foam can be characterised by its distribution of bubble areas, and of\nnumber of sides. Both distributions have an average and a width (standard\ndeviation). There are therefore at least two very different ways to\ncharacterise the disorder. The former is a geometrical measurement, while the\nlatter is purely topological. We discuss the common points and differences\nbetween both quantities. We measure them in a foam which is sheared, so that\nbubbles move past each other and the foam is \"shuffled\" (a notion we discuss).\nBoth quantities are strongly correlated; in this case (only) it thus becomes\nsufficient to use either one or the other to characterize the foam disorder. We\nsuggest applications to the analysis of other systems, including biological\ntissues.",
        "positive": "Non-Equilibrium Structural and Dynamic Behaviors of Polar Active Polymer\n  Controlled by Head Activity: Thermodynamic behavior of polymer chains out of equilibrium is a fundamental\nproblem in both polymer physics and biological physics. By using molecular\ndynamics simulation, we discover a general non-equilibrium mechanism that\ncontrols the conformation and dynamics of polar active polymer, i.e., head\nactivity commands the overall chain activity, resulting in re-entrant swelling\nof active chains and non-monotonic variation of Flory exponent $\\nu$. These\nintriguing phenomena lie in the head-controlled railway motion of polar active\npolymer, from which two oppose non-equilibrium effects emerge, i.e., dynamic\nchain rigidity and the involution of chain conformation characterized by the\nnegative bond vector correlation. The competition between these two effects\ndetermines the polymer configuration. Moreover, we identify several generic\ndynamic features of polar active polymers, i.e., linear decay of the end-to-end\nvector correlation function, polymer-size dependent crossover from ballistic to\ndiffusive dynamics, and a polymer-length independent diffusion coefficient that\nis sensitive to head activity. A simple dynamic theory is proposed to\nfaithfully explain these interesting dynamic phenomena. This sensitive\nstructural and dynamical response of active polymer to its head activity\nprovides us a practical way to control active-agents with applications in\nbiomedical engineering."
    },
    {
        "anchor": "A perturbative theory for Brownian vortexes: Brownian vortexes are stochastic machines that use static non-conservative\nforce fields to bias random thermal fluctuations into steadily circulating\ncurrents. The archetype for this class of systems is a colloidal sphere in an\noptical tweezer. Trapped near the focus of a strongly converging beam of light,\nthe particle is displaced by random thermal kicks into the nonconservative part\nof the optical force field arising from radiation pressure, which then biases\nits diffusion. Assuming the particle remains localized within the trap, its\ntime-averaged trajectory traces out a toroidal vortex. Unlike trivial Brownian\nvortexes, such as the biased Brownian pendulum, which circulate preferentially\nin the direction of the bias, the general Brownian vortex can change direction\nand even topology in response to temperature changes. Here we introduce a\ntheory based on a perturbative expansion of the Fokker-Planck equation for weak\nnon-conservative driving. The first-order solution takes the form of a modified\nBoltzmann relation and accounts for the rich phenomenology observed in\nexperiments on micrometer-scale colloidal spheres in optical tweezers.",
        "positive": "Spontaneous assembly of condensate networks during the demixing of\n  structured fluids: Liquid-liquid phase separation, whereby two liquids spontaneously demix, is\nubiquitous in industrial, environmental, and biological processes. While\nisotropic fluids are known to condense into spherical droplets in the binodal\nregion, these dynamics are poorly understood for structured fluids. Here, we\nreport the novel observation of condensate networks, which spontaneously\nassemble during the demixing of a mesogen from a solvent. Condensing mesogens\nform rapidly-elongating filaments, rather than spheres, to relieve distortion\nof a simultaneously-forming internal smectic mesophase. As filaments densify,\nthey collapse into bulged discs, lowering the elastic free energy. Additional\ndistortion is relieved by retraction of filaments into the bulged discs, which\nare straightened under tension to form a ramified network. Understanding and\ncontrolling these dynamics may provide new avenues to direct pattern formation\nor template materials."
    },
    {
        "anchor": "Caffeine Modulates the Dynamics of DODAB Membranes: Role of the Physical\n  State of the Bilayer: Caffeine (1,3,7-trimethylxanthine), an ingredient of coffee, is used\nworldwide as a psychostimulant, antioxidant, and adjuvant analgesic. To gain\ninsights into the action mechanism of caffeine, we report on its effects on the\nphase behaviour and microscopic dynamics of a dioctadecyldimethylammonium\nbromide (DODAB) lipid membrane, as studied quasielastic neutron scattering\n(QENS). Tracking the elastic scattering intensity as a function of temperature\nshowed that caffeine does not alter the phase behaviour of the DODAB membrane\nand that transition temperatures remain almost unaltered. However, QENS\nmeasurements revealed caffeine significantly modulates the microscopic dynamics\nof the lipids in the system, and that the effects depend on the structural\narrangement of the lipids in the membrane. In the coagel phase, caffeine acts\nas a plasticizing agent which enhances the membrane dynamics. However, in the\nfluid phase the opposite effect is observed; caffeine behaves like a stiffening\nagent, restricting the lipid dynamics. Further analysis of the QENS data\nindicates that in the fluid phase, caffeine restricts both lateral and internal\nmotions of the lipids in the membrane. The present study illustrates how\ncaffeine regulates the fluidity of the membrane by modulating the dynamics of\nconstituent lipids depending on the physical state of the bilayer.",
        "positive": "From Equilibrium to Steady State: The Transient Dynamics of Colloidal\n  Liquids under Shear: We investigate stresses and particle motion during the start up of flow in a\ncolloidal dispersion close to arrest into a glassy state. A combination of\nmolecular dynamics simulation, mode coupling theory and confocal microscopy\nexperiment is used to investigate the origins of the widely observed stress\novershoot and (previously not reported) super-diffusive motion in the transient\ndynamics. A link between the macro-rheological stress versus strain curves and\nthe microscopic particle motion is established. Negative correlations in the\ntransient auto-correlation function of the potential stresses are found\nresponsible for both phenomena, and arise even for homogeneous flows and almost\nGaussian particle displacements."
    },
    {
        "anchor": "Flow-induced surface charge heterogeneity in electrokinetics due to\n  Stern-layer conductance coupled to reaction kinetics: We theoretically study the electrokinetic problem of a pressure-induced\nliquid flow through a narrow long channel with charged walls, going beyond the\nclassical Helmholtz-Schmolukowski picture by considering the surprisingly\nstrong combined effect of (i) Stern layer conductance and (ii) dynamic\ncharge-regulating rather than fixed surface charges. We find that the water\nflow induces, apart from the well-known streaming potential, also a strongly\nheterogeneous surface charge and zeta-potential on chemically homogeneous\nchannel walls. Moreover, we identify a novel steady state with a nontrivial 3D\nelectric flux with 2D surface charges acting as sources and sinks. For a pulsed\npressure drop our findings also provide a first-principles explanation for\nill-understood experiments on the effect of flow on interfacial chemistry [D.\nLis et al., Science 344, 1138 (2014)].",
        "positive": "Current rectification by molecules with asymmetric tunneling barriers: A simple experimentally accessible realization of current rectification by\nmolecules (molecular films) bridging metal electrodes is described. It is based\non the spatial asymmetry of the molecule and requires only one resonant\nconducting molecular level (pi-orbital). The rectification, which is due to\nasymmetric coupling of the level to the electrodes by tunnel barriers, is\nlargely independent of the work function difference between the two electrodes.\nResults of extensive numerical studies of the family of suggested molecular\nrectifiers HS-(CH2)_m-C6H4-(CH2)_n-SH are presented. The highest rectification\nratio ~500 is achieved at m = 2 and n = 10."
    },
    {
        "anchor": "Experimental investigation of water distribution in two-phase zone\n  during gravity-dominated evaporation: We characterize the water repartition within the partially saturated\n(two-phase) zone (PSZ) during evaporation out of mixed wettable porous media by\ncontrolling the wettability of glass beads, their sizes, and as well the\nsurrounding relative humidity. Here, Capillary numbers are low and under these\nconditions, the percolating front is stabilized by gravity. Using experimental\nand numerical analyses, we find that the PSZ saturation decreases with the Bond\nnumber, where packing of smaller particles have higher saturation values than\npacking made of larger particles. Results also reveal that the extent (height)\nof the PSZ, as well as water saturation in the PSZ, both increase with\nwettability. We also numerically calculate the saturation exclusively contained\nin connected liquid films and results show that values are less than the\nexpected PSZ saturation. These results strongly reflect that the two-phase zone\nis not solely made up of connected capillary networks, but also made of\ndisconnected water clusters or pockets. Moreover, we also find that global\nsaturation (PSZ + full wet zone) decreases with wettability, confirming that\ngreater quantity of water is lost via evaporation with increasing\nhydrophilicity. These results show that connected liquid films are favored in\nmore hydrophilic systems while disconnected water pockets are favored in less\nhydrophilic systems.",
        "positive": "Simulation of the impregnation in the porous media by the Self-\n  organized Gradient Percolation method: Many processes can correspond to reactive impregnation in porous solids.\nThese processes are usually numerically computed by classical methods like\nfinite element method, finite volume method, etc. The disadvantage of these\nmethods remains in the computational time. The convergence and accuracy require\na small step-time and a small mesh size, which is expensive in computational\ntime and can induce a spurious oscillation. In order to avoid this problem, we\npropose a Self-organized Gradient Percolation algorithm. This method permits to\nreduce the CPU time drastically."
    },
    {
        "anchor": "Dendritic Growth of a Polymer on a 2D Mesoscale Square Lattice: Dendritic growth patterns exhibiting four-fold anisotropy are observed when\npolyethylene oxide undergoes phase segregation from a solution phase to a solid\nphase. When this phase transition occurs on a substrate that has patterns of\ncross-linked polyethylene oxide resist pillars made using electron beam\nlithography, the polymer grows in between the patterns giving rise to dendritic\ngrowth structures exhibiting eight-fold anisotropy. This paper presents these\nexperimental observations and explains the dendritic growth using principles of\nminimization of free energy associated with phase change. Numerical simulations\nare carried out using phase-field modeling, and the results are shown to\nqualitatively match experimental observations. The simulations reveal that the\npolymer assumes the anisotropy of the patterned lattice.",
        "positive": "How should the contact angle of a noncircular wetting boundary be\n  described?: For over 200 years, wettability has made significant contributions to\nunderstanding the properties of objects, advancing technological progress.\nTheoretical model of the contact angle (CA) for evaluating wettability has\nconstantly been modified to address relevant emerging issues. However, these\nexisting models disregard the difference in the CA along the contact line and\nuse a single-point CA to evaluate the entire contact line. From this\nperspective, there is no reasonable explanation for noncircular wetting. Here,\nwe reveal that noncircular wetting boundaries result from property differences\nin the surfaces along the boundary, and utilize friction as a comprehensive\nfactor reflecting local wettability. Average CA is proposed to evaluate the\ncontact line instead of the single-point CA, making the Cassie method and\nWenzel method obsolete, which will take an average property of the whole\nsurface as a weight coefficient of the single-point CA, ignoring the\nsubordination between physical properties and roughness in systematics."
    },
    {
        "anchor": "Self-Assembly Formed by Spherical Patchy Particles with Long-Range\n  Attraction: We report on self-assemblies formed from spherical patchy particles\ninteracting by a long-range attraction through a patch region in a\ntwo-dimensional system. We performed Monte Carlo simulations to find stable\nstructures in a system with constant number of particles under constant\ntemperature and constant pressure\n  (NPT system), in which particles interact via the Kern--Frenkel potential. We\nalso performed Brownian dynamics simulations employing an interaction potential\nsimilar to the Kern--Frenkel potential to study the formation of those\nstructures. For long-range attractive potentials, we describe how these stable\nstructures and their formation depend on the coverage of the patch. Under high\npressure, when the coverage is small, triangular lattices are formed as\nreported in previous papers. From our simulations, we find when the pressure is\nlow short chain-like structures, in which the distance between particles is\nlong, and square clusters, which are not formed with a short-range attractive\npotential, are formed. When the coverage of the patch region is large, square\nclusters are formed since the interaction between particles is stronger than\nthat for with small coverage When the coverage ratio is larger than 0.5, the\ndirection of the patch is perpendicular to the plane in which the particles are\nplaced.",
        "positive": "Discharge of elongated grains from silo with rotating bottom: We study the flow of elongated grains (wooden pegs of length $L$=20 mm with\ncircular cross section of diameter $d_c$=6 and 8 mm) from a silo with a\nrotating bottom and a circular orifice of diameter $D$. In the small orifice\nrange ($D/d<5$) clogs are mostly broken by the rotating base, and the flow is\nintermittent with avalanches and temporary clogs. Here\n$d\\equiv(\\frac{3}{2}d_c^2L)^{1/3}$ is the effective grain diameter. Unlike for\nspherical grains, for rods the flow rate $W$ clearly deviates from the power\nlaw dependence $W\\propto (D-kd)^{2.5}$ at lower orifice sizes in the\nintermittent regime, where $W$ is measured in between temporary clogs only.\nInstead, below about $D/d<3$ an exponential dependence $W\\propto e^{\\kappa D}$\nis detected. Here $k$ and $\\kappa$ are constants of order unity. Even more\nimportantly, rotating the silo base leads to a strong -- more than 50% --\ndecrease of the flow rate, which otherwise does not depend significantly on the\nvalue of $\\omega$ in the continuous flow regime. In the intermittent regime,\n$W(\\omega)$ appears to follow a non-monotonic trend, although with considerable\nnoise. A simple picture, in terms of the switching from funnel flow to mass\nflow and the alignment of the pegs due to rotation, is proposed to explain the\nobserved difference between spherical and elongated grains. We also observe\nshear induced orientational ordering of the pegs at the bottom such that their\nlong axes in average are oriented at a small angle $\\langle\\theta\\rangle\n\\approx 15^\\circ$ to the motion of the bottom."
    },
    {
        "anchor": "Enhancing protein drop stability for crystallization by chemical\n  patterning: Motion of protein drops on crystallization media during routine handling is a\nmajor factor affecting the reproducibility of crystallization conditions. Drop\nstability can be enhanced by chemical patterning to more effectively pin the\ndrop's contact line. As an example, a hydrophilic area is patterned on an\ninitially flat hydrophobic glass slide. The drop remains confined to the\nhydrophilic area, and the maximum drop size that remains stable when the slide\nis rotated to the vertical position increases. This simple method is readily\nscalable and has the potential to significantly improve outcomes in hanging and\nsitting drop crystallization.",
        "positive": "Anisotropic colloids through non-trivial buckling: We present a study on buckling of colloidal particles, including\nexperimental, theoretical and numerical developments. Oil-filled thin shells\nprepared by emulsion templating show buckling in mixtures of water and ethanol,\ndue to dissolution of the core in the external medium. This leads to\nconformations with a single depression, either axisymmetric or polygonal\ndepending on the geometrical features of the shells. These conformations could\nbe theoretically and/or numerically reproduced in a model of homogeneous\nspherical thin shells with bending and stretching elasticity, submitted to an\nisotropic external pressure."
    },
    {
        "anchor": "Ionic content dependence of viscoelasticity of lyotropic chromonic\n  liquid crystal sunset yellow: A lyotropic chromonic liquid crystal (LCLC) is an orientationally ordered\nsystem made by self-assembled aggregates of charged organic molecules in water,\nbound by weak non-covalent attractive forces and stabilized by electrostatic\nrepulsions. We determine how the ionic content of the LCLC, namely the presence\nof mono- and divalent salts and pH enhancing agent, alter the viscoelastic\nproperties of the LCLC. Aqueous solutions of the dye Sunset Yellow with a\nuniaxial nematic order are used as an example. By applying a magnetic field to\nimpose orientational deformations, we measure the splay $K_1$, twist $K_2$ and\nbend $K_3$ elastic constants and rotation viscosity $\\gamma_1$ as a function of\nconcentration of additives. The data indicate that the viscoelastic parameters\nare influenced by ionic content in dramatic and versatile ways. For example,\nthe monovalent salt NaCl decreases $K_3$ and $K_2$ and increases $\\gamma_1$,\nwhile an elevated pH decreases all the parameters. We attribute these features\nto the ion-induced changes in length and flexibility of building units of LCLC,\nthe chromonic aggregates, a property not found in conventional thermotropic and\nlyotropic liquid crystals formed by covalently bound units of fixed length.",
        "positive": "Wallpaper group kirigami: Kirigami, the art of paper cutting, has become a paradigm for mechanical\nmetamaterials in recent years. The basic building blocks of any kirigami\nstructures are repetitive deployable patterns that derive inspiration from\ngeometric art forms and simple planar tilings. Here we complement these\napproaches by directly linking kirigami patterns to the symmetry associated\nwith the set of seventeen repeating patterns that fully characterize the space\nof periodic tilings of the plane. We start by showing how to construct\ndeployable kirigami patterns using any of the wallpaper groups, and then design\nsymmetry-preserving cut patterns to achieve arbitrary size changes via\ndeployment. We further prove that different symmetry changes can be achieved by\ncontrolling the shape and connectivity of the tiles and connect these results\nto the underlying kirigami-based lattice structures. All together, our work\nprovides a systematic approach for creating a broad range of kirigami-based\ndeployable structures with any prescribed size and symmetry properties."
    },
    {
        "anchor": "Binary Blends of Diblock Copolymers: An Efficient Route to Complex\n  Spherical Packing Phases: The phase behaviour of binary blends composed of A$_1$B$_1$ and A$_2$B$_2$\ndiblock copolymers is systematically studied using the polymeric\nself-consistent field theory, focusing on the formation and relative stability\nof various spherical packing phases. The results are summarized in a set of\nphase diagrams covering a large phase space of the system. Besides the commonly\nobserved body-centered-cubic (BCC) phase, complex spherical packing phases\nincluding the Frank-Kasper A15 and $\\sigma$ and the Laves C14 and C15 phases\ncould be stabilized by the addition of longer A$_2$B$_2$-copolymers to\nasymmetric A$_1$B$_1$-copolymers. Stabilizing the complex spherical packing\nphases requires that the added A$_2$B$_2$-copolymers have a longer A-block and\nan overall chain length at least comparable to the host copolymer chains. A\ndetailed analysis of the block distributions reveals the existence of inter-\nand intra-domain segregation of different copolymers, which depends sensitively\non the copolymer length ratio and composition. The predicted phase behaviours\nof the A$_1$B$_1$/A$_2$B$_2$ diblock copolymer blends are in good agreement\nwith available experimental and theoretical results. The study demonstrated\nthat binary blends of diblock copolymers provide an efficient route to regulate\nthe emergence and stability of complex spherical packing phases.",
        "positive": "From avalanches to fluid flow: A continuous picture of grain dynamics\n  down a heap: Surface flows are excited by steadily adding spherical glass beads to the top\nof a heap. To simultaneously characterize the fast single-grain dynamics and\nthe much slower collective intermittency of the flow, we extend\nphoton-correlation spectroscopy via fourth-order temporal correlations in the\nscattered light intensity. We find that microscopic grain dynamics during an\navalanche are similar to those in the continuous flow just above the\ntransition. We also find that there is a minimum jamming time, even arbitrarily\nclose to the transition."
    },
    {
        "anchor": "Motion of grains in a vibrated U-tube: We investigate experimentally the behavior of the rate of growth of a column\nof grains, in a partially filled vertically shaken U-tube. For the set of\nfrequencies used we identify three qualitatively different behaviors for the\ngrowth rate $\\gamma$ as a function of the dimensionless acceleration $\\Gamma$:\n1) an interval of zero growth for low $\\Gamma$ with a smooth change to nonzero\ngrowth, analogous to a continuous phase transition; 2) a sigmoidal region for\n$\\gamma$ at intermediate values of the dimensionless acceleration $\\Gamma$; and\n3) an abrupt change from high values of $\\gamma$ to zero growth at high values\nof $\\Gamma$, similar to a first order phase transition. We obtain that our data\nis well described by a simple differential equation for the change of the\ngrowth rate with the dimensionless acceleration of the vertical vibrations.",
        "positive": "Kinetics and mechanism of proton transport across membrane nanopores: We use computer simulations to study the kinetics and mechanism of proton\npassage through a narrow-pore carbon-nanotube membrane separating reservoirs of\nliquid water. Free energy and rate constant calculations show that protons move\nacross the membrane diffusively in single-file chains of hydrogen-bonded water\nmolecules. Proton passage through the membrane is opposed by a high barrier\nalong the effective potential, reflecting the large electrostatic penalty for\ndesolvation and reminiscent of charge exclusion in biological water channels.\nAt neutral pH, we estimate a translocation rate of about 1 proton per hour and\ntube."
    },
    {
        "anchor": "Atomistic simulation of PDADMAC/PSS oligoelectrolyte multilayers:\n  overall comparison of tri- and tetra-layer systems: By employing large-scale molecular dynamics simulations of atomistically\nresolved oligoelectrolytes in aqueous solutions, we study in detail the first\nfour layer-by-layer deposition cycles of an oligoelectrolyte multilayer made of\npoly(diallyl dimethyl ammonium chloride)/poly(styrene sulfonate sodium salt)\n(PDADMAC/PSS). The multilayers are grown on a silica substrate in 0.1M {NaCl}\nelectrolyte solutions and the swollen structures are then subsequently exposed\nto varying added salt concentration. We investigated the microscopic properties\nof the films, analyzing in detail the differences between three- and\nfour-layers systems. Our simulations provide insights on the early stages of\ngrowth of a multilayer, which are particularly challenging for experimental\nobservations. We found a rather strong entanglement of the oligoelectrolytes,\nwith a fuzzy layering of the film structure. The main charge compensation\nmechanism is for all cases intrinsic, whereas extrinsic compensation is\nrelatively ehanced for the layer of the last deposition cycle. In addition, we\nquantified other fundamental observables of these systems, as the film\nthickness, water uptake, and overcharge fractions for each deposition layer.",
        "positive": "Tuning nucleation kinetics via nonequilibrium chemical reactions: Unlike fluids at thermal equilibrium, biomolecular mixtures in living systems\ncan sustain nonequilibrium steady states, in which active processes modify the\nconformational states of the constituent molecules. Despite qualitative\nsimilarities between liquid--liquid phase separation in these systems, the\nextent to which the phase-separation kinetics differ remains unclear. Here we\nshow that inhomogeneous chemical reactions can alter the nucleation kinetics of\nliquid--liquid phase separation in a manner that is consistent with classical\nnucleation theory, but can only be rationalized by introducing a nonequilibrium\ninterfacial tension. We identify conditions under which nucleation can be\naccelerated without changing the energetics or supersaturation, thus breaking\nthe correlation between fast nucleation and strong driving forces that is\ntypical of phase separation and self-assembly at thermal equilibrium."
    },
    {
        "anchor": "A Conceptual Approach to Two-Scale Constitutive Modelling For\n  Hydro-Mechanical Coupling: Large scale modelling of fluid flow coupled with solid failure in geothermal\nreservoirs or hydrocarbon extraction from reservoir rocks usually involves\nbehaviours at two scales: lower scale of the inelastic localization zone, and\nlarger scale of the bulk continuum where elastic behaviour can be reasonably\nassumed. The hydraulic conductivities corresponding to the mechanical\nproperties at these two scales are different. In the bulk elastic host rock,\nthe hydraulic conductivity does not vary much with the deformation, while it\nsignificantly changes in the lower scale of the localization zone due to\ninelastic deformation. Increase of permeability due to fracture and/or\ndilation, or reduction of permeability due to material compaction can take\nplace inside this zone. The challenge is to predict the evolution of hydraulic\nconductivities coupled with the mechanical behaviour of the material in all\nstages of the deformation process. In the early stage of diffuse deformation,\nthe permeability of the material can be reasonably assumed to be homogenous\nover the whole Representative Volume Element (RVE) However, localized failure\nresults in distinctly different conductivities in different parts of the RVE.\nThis paper establishes a general framework and corresponding field equations to\ndescribe the hydro-mechanical coupling in both diffuse and localized stages of\ndeformation in rocks. In particular, embedding the lower scale hydro-mechanical\nbehaviour of the localization zone inside an elastic bulk, together with their\ncorresponding effective sizes, helps effectively deal with scaling issues in\nlarge-scale modelling. Preliminary results are presented which demonstrate the\npromising features of this new approach.",
        "positive": "Conditions for extreme sensitivity of protein diffusion in membranes to\n  cell environments: We study protein diffusion in multicomponent lipid membranes close to a rigid\nsubstrate separated by a layer of viscous fluid. The large-distance, long-time\nasymptotics for Brownian motion are calculated using a nonlinear stochastic\nNavier-Stokes equation including the effect of friction with the substrate. The\nadvective nonlinearity, neglected in previous treatments, gives only a small\ncorrection to the renormalized viscosity and diffusion coefficient at room\ntemperature. We find, however, that in realistic multicomponent lipid mixtures,\nclose to a critical point for phase separation, protein diffusion acquires a\nstrong power-law dependence on temperature and the distance to the substrate\n$H$, making it much more sensitive to cell environment, unlike the logarithmic\ndependence on $H$ and very small thermal correction away from the critical\npoint."
    },
    {
        "anchor": "Microscopic Aspects of Stretched Exponential Relaxation (SER) in\n  Homogeneous Molecular and Network Glasses and Polymers: Because the theory of SER is still a work in progress, the phenomenon itself\ncan be said to be the oldest unsolved problem in science, as it started with\nKohlrausch in 1847. Many electrical and optical phenomena exhibit SER with\nprobe relaxation I(t) ~ exp[-(t/{\\tau}){\\beta}], with 0 < {\\beta} < 1. Here\n{\\tau} is a material-sensitive parameter, useful for discussing chemical\ntrends. The \"shape\" parameter {\\beta} is dimensionless and plays the role of a\nnon-equilibrium scaling exponent; its value, especially in glasses, is both\npractically useful and theoretically significant. The mathematical complexity\nof SER is such that rigorous derivations of this peculiar function were not\nachieved until the 1970's. The focus of much of the 1970's pioneering work was\nspatial relaxation of electronic charge, but SER is a universal phenomenon, and\ntoday atomic and molecular relaxation of glasses and deeply supercooled liquids\nprovide the most reliable data. As the data base grew, the need for a\nquantitative theory increased; this need was finally met by the\ndiffusion-to-traps topological model, which yields a remarkably simple\nexpression for the shape parameter {\\beta}, given by d*/(d* + 2). At first\nsight this expression appears to be identical to d/(d + 2), where d is the\nactual spatial dimensionality, as originally derived. The original model,\nhowever, failed to explain much of the data base. Here the theme of earlier\nreviews, based on the observation that in the presence of short-range forces\nonly d* = d = 3 is the actual spatial dimensionality, while for mixed short-\nand long-range forces, d* = fd = d/2, is applied to four new spectacular\nexamples, where it turns out that SER is useful not only for purposes of\nquality control, but also for defining what is meant by a glass in novel\ncontexts. (Please see full abstract in main text)",
        "positive": "Local loop opening in untangled ring polymer melts: A detailed \"Feynman\n  test\" of models for the large scale structure: The conformational statistics of ring polymers in melts or dense solutions is\nstrongly affected by their quenched microscopic topological state. The effect\nis particularly strong for untangled (i.e. non-concatenated and unknotted)\nrings, which are known to crumple and segregate. Here we study these systems\nusing a computationally efficient multi-scale approach, where we combine\nmassive simulations on the fiber level with the explicit construction of\nuntangled ring melt configurations based on theoretical ideas for their large\nscale structure. We find (i) that topological constraints may be neglected on\nscales below the standard entanglement length, $L_e$, (ii) that rings with a\nsize $1 \\le L_r/L_e \\le 30$ exhibit nearly ideal lattice tree behavior\ncharacterized by primitive paths which are randomly branched on the\nentanglement scale, and (iii) that larger rings are compact with gyration radii\n$\\langle R_g^2(L_r) \\rangle \\propto L_r^{2/3}$. The detailed comparison between\nequilibrated and constructed ensembles allows us to perform a `Feynman test' of\nour understanding of untangled rings: can we convert ideas for the large-scale\nring structure into algorithms for constructing (nearly) equilibrated ring melt\nsamples? We show that most structural observables are quantitatively reproduced\nby two different construction schemes: hierarchical crumpling and ring melts\nderived from the analogy to interacting branched polymers. However, the latter\nfail the `Feynman test' with respect to the magnetic radius, $R_m$, which we\nhave defined based on an analogy to magnetostatics. While $R_m$ is expected to\nvanish for double-folded structures, the observed values of $\\langle R_m^2(L_r)\n\\rangle \\propto \\langle R_g^2(L_r) \\rangle$ provide a simple and\ncomputationally convenient measure of the presence of a non-negligible amount\nof local loop opening in crumpled rings."
    },
    {
        "anchor": "Acoustic wave propagation in two-phase heterogeneous porous media: The propagation of an acoustic wave through two-phase porous media with\nspatial variation in porosity is studied. The evolutionary wave equation is\nderived, and the propagation of an acoustic wave is numerically analyzed in\napplication to marine sediments with various physical parameters.",
        "positive": "Experimental Studies of the Jamming Behaviour of Triblock Copolymer\n  Solutions and Triblock Copolymer-Anionic Surfactant Mixture: Photon correlation spectroscopy and rheological measurements are performed to\ninvestigate the microscopic dynamics and mechanical responses of aqueous\nsolutions of triblock copolymers and aqueous mixtures of triblock copolymers\nand anionic surfactants. Increasing the concentration of triblock copolymers\nresults in a sharp increase in the magnitude of the complex moduli\ncharacterising the samples. This is understood in terms of the changes in the\naggregation and packing behaviours of the copolymers and the constraints\nimposed upon their dynamics due to increased close packing. The addition of\nsuitable quantities of an anionic surfactant to a strongly elastic copolymer\nsolution results in a decrease in the complex moduli of the samples by several\ndecades. It is argued that the shape anisotropy and size polydispersity of the\nmicelles comprising mixtures cause dramatic changes in the packing behaviour,\nresulting in sample unjamming and the observed decrease in complex moduli.\nFinally, a phase diagram is constructed in the temperature-surfactant\nconcentration plane to summarise the jamming-unjamming behaviour of aggregates\nconstituting triblock copolymer-anionic surfactant mixtures."
    },
    {
        "anchor": "Quantum Diffusion in Polaron Model of poly(dG)-poly(dC) and\n  poly(dA)-poly(dT) DNA polymers: We numerically investigate quantum diffusion of an electron in a model of\npoly(dG)-poly(dC) and poly(dA)-poly(dT) DNA polymers with fluctuation of the\nparameters due to the impact of colored noise. The randomness is introduced by\nfluctuations of distance between two consecutive bases along the stacked base\npairs. We demonstrate that in the model the decay time of the correlation can\ncontrol the spread of the electronic wavepacket. Furthermore it is shown that\nin a motional narrowing regime the averaging over fluctuation causes ballistic\npropagation of the wavepacket, and in the adiabatic regime the electronic\nstates are affected by localization.",
        "positive": "Local rheological measurements in the granular flow around an intruder: The rheological properties of granular matter within a two-dimensional flow\naround a moving disk is investigated experimentally. Using a combination of\nphotoelastic and standard tessellation techniques, the strain and stress\ntensors are estimated at the grain scale in the time-averaged flow field around\na large disk pulled at constant velocity in an assembly of smaller disks. On\nthe one hand, one observes inhomogeneous shear rate and strongly localized\nshear stress and pressure fields. On the other hand, a significant dilation\nrate, which has the same magnitude as the shear strain rate, is reported.\nSignificant deviations are observed with local rheology that justify the need\nof searching for a non-local rheology."
    },
    {
        "anchor": "The effect of polymorphism on the structural, dynamic and dielectric\n  properties of plastic crystal water: A molecular dynamics simulation\n  perspective: We have employed molecular dynamics simulations based on the TIP4P/2005 water\nmodel to investigate the local structural, dynamical, and dielectric properties\nof the two recently reported body-centered-cubic and face-centered-cubic\nplastic crystal phases of water. Our results reveal significant differences in\nthe local orientational structure and rotational dynamics of water molecules\nfor the two polymorphs. The probability distributions of trigonal and\ntetrahedral order parameters exhibit a multi-modal structure, implying the\nexistence of significant local orientational heterogeneities, particularly in\nthe face-centered-cubic phase. The calculated hydrogen bond statistics and\ndynamics provide further indications of the existence of a strongly\nheterogeneous and rapidly interconverting local orientational structural\nnetwork in both polymorphs. We have observed a hindered molecular rotation,\nmuch more pronounced in the body-centered-cubic phase, which is reflected by\nthe decay of the fourth-order Legendre reorientational correlation functions\nand angular Van Hove functions. Molecular rotation, however, is additionally\nhindered in the high-pressure liquid compared to the plastic crystal phase. The\nresults obtained also reveal significant differences in the dielectric\nproperties of the polymorphs due to the different dipolar orientational\ncorrelation characterizing each phase.",
        "positive": "The influence of Gaussian pinning on the melting scenario of a\n  two-dimensional soft-disk system: First-Order versus Continuous Transition: Two-dimensional systems are realized experimentally as thin layers on a\nsubstrate. The substrate can have some imperfections (defects of the\ncrystalline structure, chemical impurities, etc.), which demonstrate stronger\ninteraction with the particles of the two-dimensional layer than the rest of\nthe system. Such randomly distributed centers of strong interactions are called\n\"pinning centers\". The presence of random pinning can substantially change the\nbehavior of the system. It not only shifts the melting point of the system, but\ncan also change the melting scenario itself. In the present paper the influence\nof Gaussian pinning on the melting scenario of a two-dimensional system of soft\ndisks is studied by means of molecular dynamics simulation. We randomly\nintroduce into the system of soft disks a set of \"pinning centers\" which\nattract the particles via the Gauss potential. We observe that increasing the\ndepth of a Gaussian well leads to a change in the melting scenario of the\nsystem. The results demonstrate that simple kind of quenched disorder can\nsignificantly affect the melting scenario of two-dimensional systems, offering\nthe possibility of its introduction in complex experiments and studying its\ninfluence on the self-assembly and phase diagram of two-dimensional systems in\nrotating external fields."
    },
    {
        "anchor": "Patterns on a Roll: A Method for Continuous Feed Nanoprinting: Exploiting elastic instability in thin films has proven a robust method for\ncreating complex patterns and structures across a wide range of lengthscales.\nEven the simplest of systems, an elastic membrane with a lattice of pores,\nunder mechanical strain, generates complex patterns featuring long-range\norientational order. When we promote this system to a curved surface, in\nparticular, a cylindrical membrane, a novel set of features, patterns and\nbroken symmetries appears. The newfound periodicity of the cylinder allows for\na novel continuous method for nanoprinting.",
        "positive": "Power law relaxation and glassy dynamics in Lebwohl-Lasher model near\n  isotropic-nematic phase transition: Orientational dynamics in a liquid crystalline system near the\nisotropic-nematic (I-N) phase transition is studied using Molecular Dynamics\nsimulations of the well-known Lebwohl-Lasher (LL) model. As the I-N transition\ntemperature is approached from the isotropic side, we find that the decay of\nthe orientational time correlation functions (OTCF) slows down noticeably,\ngiving rise to a power law decay at intermediate timescales. The angular\nvelocity time correlation function also exhibits a rather pronounced power law\ndecay near the I-N boundary. In the mean squared angular displacement at\ncomparable timescales, we observe the emergence of a \\emph{subdiffusive regime}\nwhich is followed by a \\emph{superdiffusive regime} before the onset of the\nlong-time diffusive behavior. We observe signature of dynamical heterogeneity\nthrough \\emph{pronounced non-Gaussian behavior in orientational motion}\nparticularly at lower temperatures. This behavior closely resembles what is\nusually observed in supercooled liquids. We obtain the free energy as a\nfunction of orientational order parameter by the use of transition matrix Monte\nCarlo method. The free energy surface is flat for the system considered here\nand the barrier between isotropic and nematic phases is vanishingly small for\nthis weakly first-order phase transition, hence allowing large scale,\ncollective and correlated orientational density fluctuations. This might be\nresponsible for the observed power law decay of the OTCFs."
    },
    {
        "anchor": "Modeling of the interaction of rigid wheels with dry granular media: We analyze the capabilities of various recently developed techniques, namely\nResistive Force Theory (RFT) and continuum plasticity implemented with the\nMaterial Point Method (MPM), in capturing dynamics of wheel--dry granular media\ninteractions. We compare results to more conventionally accepted methods of\nmodeling wheel locomotion. While RFT is an empirical force model for\narbitrarily-shaped bodies moving through granular media, MPM-based continuum\nmodeling allows the simulation of full granular flow and stress fields. RFT\nallows for rapid evaluation of interaction forces on arbitrary shaped intruders\nbased on a local surface stress formulation depending on depth, orientation,\nand movement of surface elements. We perform forced-slip experiments for three\ndifferent wheel types and three different granular materials, and results are\ncompared with RFT, continuum modeling, and a traditional terramechanics\nsemi-empirical method. Results show that for the range of inputs considered,\nRFT can be reliably used to predict rigid wheel granular media interactions\nwith accuracy exceeding that of traditional terramechanics methodology in\nseveral circumstances. Results also indicate that plasticity-based continuum\nmodeling provides an accurate tool for wheel-soil interaction while providing\nmore information to study the physical processes giving rise to resistive\nstresses in granular media.",
        "positive": "Phase transitions on non-uniformly curved surfaces: Coupling between\n  phase and location: For particles confined to two dimensions, any curvature of the surface\naffects the structural, kinetic and thermodynamic properties of the system. If\nthe curvature is non-uniform, an even richer range of behaviours can emerge.\nUsing a combination of bespoke Monte Carlo, molecular dynamics and\nbasin-hopping methods, we show that the stable states of attractive colloids\nconfined to non-uniformly curved surfaces are distinguished not only by the\nphase of matter but also by their location on the surface. Consequently, the\ntransitions between these states involve cooperative migration of the entire\ncolloidal assembly. We demonstrate these phenomena on toroidal and sinusoidal\nsurfaces for model colloids with different ranges of interactions as described\nby the Morse potential. In all cases, the behaviour can be rationalised in\nterms of three universal considerations: cluster perimeter, stress, and the\npacking of next-nearest neighbours."
    },
    {
        "anchor": "Kinematic flow patterns in slow deformation of a dense granular material: The kinematic flow pattern in slow deformation of a model dense granular\nmedium is studied at high resolution using \\emph{in situ} imaging, coupled with\nparticle tracking. The deformation configuration is indentation by a flat punch\nunder macroscopic plane-strain conditions. Using a general analysis method,\nvelocity gradients and deformation fields are obtained from the disordered\ngrain arrangement, enabling flow characteristics to be quantified. The key\nobservations are the formation of a stagnation zone, as in dilute granular flow\npast obstacles; occurrence of vortices in the flow immediately underneath the\npunch; and formation of distinct shear bands adjoining the stagnation zone. The\ntransient and steady state stagnation zone geometry, as well as the strength of\nthe vortices and strain rates in the shear bands, are obtained from the\nexperimental data. All of these results are well-reproduced in exact-scale\nNon-Smooth Contact Dynamics (NSCD) simulations. Full 3D numerical particle\npositions from the simulations allow extraction of flow features that are\nextremely difficult to obtain from experiments. Three examples of these, namely\nmaterial free surface evolution, deformation of a grain column below the punch\nand resolution of velocities inside the primary shear band, are highlighted.\nThe variety of flow features observed in this model problem also illustrates\nthe difficulty involved in formulating a complete micromechanical analytical\ndescription of the deformation.",
        "positive": "Non-simple flow behavior in a polar van der Waals liquid: structural\n  relaxation under scope: The non-exponential character of the structural relaxation is considered one\nof the hallmarks of the glassy dynamics and in this context, the singular shape\nobserved by dielectric techniques has attracted the attention of the community\nfor long time. Particularly, the exceptionally narrow dielectric response of\npolar glass formers has been attributed so far to dipolar cross correlations.\nHere we show that dipole interactions can couple to shear stress and modify the\nflow behavior preventing the occurrence of the simple liquid behavior. We\ndiscuss our findings in the general framework of the glassy dynamics and the\nrole of intermolecular interactions."
    },
    {
        "anchor": "Rototaxis: localization of active motion under rotation: The ability to navigate in complex, inhomogeneous environments is fundamental\nto survival at all length scales, giving rise to the rapid development of\nvarious subfields in bio-locomotion such as the well established concept of\nchemotaxis. In this work, we extend this existing notion of taxis to rotating\nenvironments and introduce the idea of roto-taxis to bio-locomotion. In\nparticular, we explore both overdamped and inertial dynamics of a model\nsynthetic self-propelled particle in the presence of constant global rotation,\nfocusing on the particle's ability to localize near a rotation center as a\nsurvival strategy. We find that in the overdamped regime, the swimmer is in\ngeneral able to generate a self restoring active torque that enables it to\nremain on stable epicyclical-like trajectories. On the other hand, for\nunderdamped motion with inertial effects, the intricate competition between\nself-propulsion and inertial forces, in conjunction with the rototactic torque\nleads to complex dynamical behavior with non-trivial phase space of initial\nconditions which we reveal by numerical simulations. Our results are relevant\nfor a wide range of setups, from vibrated granular matter on turntables to\nmicroorganisms or animals swimming near swirls or vortices.",
        "positive": "Protein-Polymer Mixtures in the Colloid Limit: Aggregation,\n  Sedimentation and Crystallization: While proteins have been treated as particles with a spherically symmetric\ninteraction, of course in reality the situation is rather more complex. A\nsimple step towards higher complexity is to treat the proteins as\nnon--spherical particles and that is the approach we pursue here. We\ninvestigate the phase behavior of enhanced green fluorescent protein (eGFP)\nunder the addition of a non--adsorbing polymer, polyethylene glycol (PEG). From\nsmall angle x-ray scattering we infer that the eGFP undergoes dimerization and\nwe treat the dimers as spherocylinders with aspect ratio $L/D-1 = 1.05$.\nDespite the complex nature of the proteins, we find that the phase behaviour is\nsimilar to that of hard spherocylinders with ideal polymer depletant,\nexhibiting aggregation and, in a small region of the phase diagram,\ncrystallization. By comparing our measurements of the onset of aggregation with\npredictions for hard colloids and ideal polymers [S.V. Savenko and M. Dijkstra,\nJ. Chem. Phys 124, 234902 (2006) and F. lo Verso et al., Phys. Rev. E 73,\n061407 (2006)] we find good agreement, which suggests that the eGFP proteins\nare consistent with hard spherocylinders and ideal polymer."
    },
    {
        "anchor": "Anchoring effects at the isotropic-nematic interface in liquid crystals: The isotropic-to-nematic transition in liquid crystals is studied in d=3\nspatial dimensions. A simulation method is proposed to measure the angle\ndependent interfacial tension g(theta), with theta the anchoring angle of the\nnematic phase at the interface. In addition, an alternative liquid crystal\nmodel is introduced, defined on a lattice. The advantage of the lattice model\nis that accurate simulations of anchoring effects become possible. For the\nlattice model, g(theta) depends sensitively on the nearest-neighbor pair\ninteraction, and both stable and metastable anchoring angles can be detected.\nWe also measure g(theta) for an off-lattice fluid of soft rods. For soft rods,\nonly one stable anchoring angle is found, corresponding to homogeneous\nalignment of the nematic director in the plane of the interface. This finding\nis in agreement with most theoretical predictions obtained for hard rods.",
        "positive": "Gelation dynamics upon pressure-induced liquid-liquid phase separation\n  in a water-lysozyme solution: Employing X-ray photon correlation spectroscopy we measure the kinetics and\ndynamics of a pressure-induced liquid-liquid phase separation (LLPS) in a\nwater-lysozyme solution. Scattering invariants and kinetic information provide\nevidence that the system reaches the phase boundary upon pressure-induced LLPS\nwith no sign of arrest. The coarsening slows down with increasing quench\ndepths. The $g_2$-functions display a two-step decay with a gradually\nincreasing non-ergodicity parameter typical for gelation. We observe fast\nsuperdiffusive ($\\gamma \\geq 3/2$) and slow subdiffusive ($\\gamma < 0.6$)\nmotion associated with fast viscoelastic fluctuations of the network and a slow\nviscous coarsening process, respectively. The dynamics age linear with time\n$\\tau \\propto t_\\mathrm{w}$ and we observe the onset of viscoelastic relaxation\nfor deeper quenches. Our results suggest that the protein solution gels upon\nreaching the phase boundary."
    },
    {
        "anchor": "Scaling Relations of Viscous Fingers in Anisotropic Hele-Shaw Cells: Viscous fingers in a channel with surface tension anisotropy are numerically\nstudied. Scaling relations between the tip velocity v, the tip radius and the\npressure gradient are investigated for two kinds of boundary conditions of\npressure, when v is sufficiently large. The power-law relations for the\nanisotropic viscous fingers are compared with two-dimensional dendritic growth.\nThe exponents of the power-law relations are theoretically evaluated.",
        "positive": "Soil granular dynamics on-a-chip: fluidization inception under scrutiny: Predicting rapid and slower soil evolution remains a scientific challenge.\nThis process involves poorly understood aspects of disordered granular matter\nand dense suspension dynamics. This study presents a novel two-dimensional\nexperiment on a small-scale chip structure; this allows the observation of the\ndeformation at the particle scale of a large-grained sediment bed, under\nconditions where friction dominate over cohesive and thermal forces, and with\nan imposed fluid flow. Experiments are performed at conditions which span the\nparticle resuspension criterion, and particle motion is detected and analyzed.\nThe void size population and statistics of particle trajectories bring insight\nto the sediment dynamics near fluidization conditions. Specifically, particle\nrearrangement and net bed compaction are observed at flow rates significantly\nbelow the criterion for instability growth. Above a threshold, a large vertical\nchannel through the bed forms. In the range of flow rates where channelization\ncan occur, the coexistence of compacting and dilating bed scenarios is\nobserved. The results of the study enhance our capacity for modeling of both\nslow dynamics and eventual rapid destabilization of sediment beds.\nMicrofluidics channel soil-on-a-chip studies open avenues to new investigations\nincluding dissolution-precipitation, fine particles transport, or\nmicro-organisms swimming and population growth, which may depend on mechanics\nof the porous media itself."
    },
    {
        "anchor": "Lattice Boltzmann simulations on the tumbling to tank-treading\n  transition: effects of membrane viscosity: The tumbling to tank-treading (TB-TT) transition for red blood cells (RBCs)\nhas been widely investigated, with a main focus on the effects of the viscosity\nratio $\\lambda$ (i.e., the ratio between the viscosities of the fluids inside\nand outside the membrane) and the shear rate $\\dot{\\gamma}$ applied to the RBC.\nHowever, the membrane viscosity $\\mu_m$ plays a major role in a realistic\ndescription of RBC's dynamics, and only a few works have systematically focused\non its effects on the TB-TT transition. In this work, we provide a parametric\ninvestigation on the effect of membrane viscosity $\\mu_m$ on the TB-TT\ntransition, for a single RBC. It is found that, at fixed viscosity ratios\n$\\lambda$, larger values of $\\mu_m$ lead to an increased range of values of\ncapillary number at which the TB-TT transition occurs. We systematically\nquantify such an increase by means of mesoscale numerical simulations based on\nthe lattice Boltzmann models.",
        "positive": "Snap buckling of a confined thin elastic sheet: A growing or compressed thin elastic sheet adhered to a rigid substrate can\nexhibit a buckling instability, forming an inward hump. Our study shows that\nthe strip morphology depends on the delicate balance between the compression\nenergy and the bending energy. We find that this instability is a first order\nphase transition between the adhered solution and the buckled solution whose\nmain control parameter is related to the sheet stretchability. In the nearly-\nunstretchable regime we provide an analytic expression for the critical\nthreshold. Compressibility is the key assumption which allows us to resolve the\napparent paradox of an unbounded pressure exerted on the external wall by a\nconfined flexible loop."
    },
    {
        "anchor": "Elastic Response of Wire Frame Glasses. II. Three Dimensional Systems: We study the elastic response of rigid, wire frame particles in concentrated,\nglassy suspensions to a step strain by applying the simple, geometric methods\ndeveloped in part I. The wire frame particles are comprised of thin, rigid rods\nof length $L$ and their number density, $\\rho$, is such that $\\rho L^3 \\gg 1$.\nWe specifically compare rigid rods to L-shapes made of two equal length rods\njoined at right angles. The behaviour of wire frames is found to be strikingly\ndifferent from that of rods. The linear elasticity scales like $\\rho^3 L^6$ for\nL-shaped particles, whereas it scales proportional to $\\rho$ for rods and the\nnon-linear response shows a transition from shear hardening to shear softening\nat a critical density $\\rho_c \\sim \\sqrt{K / k_B T L^6}$, where $K$ is the\nbending modulus of the particles. For realistic particles made of double\nstranded DNA, this transition occurs at densities of about $\\rho L^3 \\sim 10$.\nThe reason for these differences is that wire frames can be forced to bend by\nthe entanglements with their surroundings, whereas rods always remain straight.\nThis is found to be very important even for small strains, with most particles\nbeing bent above a critical strain $\\gamma_c \\sim (\\rho L^3)^{-1}$.",
        "positive": "Dynamics of coreless vortices and rotation-induced dissipation peak in\n  superfluid films on rotating porous substrates: We analyze dynamics of 3D coreless vortices in superfluid films covering\nporous substrates. The 3D vortex dynamics is derived from the 2D dynamics of\nthe film. The motion of a 3D vortex is a sequence of jumps between neighboring\nsubstrate cells, which can be described, nevertheless, in terms of\nquasi-continuous motion with average vortex velocity. The vortex velocity is\nderived from the dissociation rate of vortex-antivortex pairs in a 2D film,\nwhich was developed in the past on the basis of the Kosterlitz-Thouless theory.\nThe theory explains the rotation-induced dissipation peak in torsion-oscillator\nexperiments on $^4$He films on rotating porous substrates and can be used in\nthe analysis of other phenomena related to vortex motion in films on porous\nsubstrates."
    },
    {
        "anchor": "Theory of swimming filaments in viscoelastic media: Motivated by the swimming of sperm in the non-Newtonian fluids of the female\nmammalian reproductive tract, we examine the swimming of filaments in the\nnonlinear viscoelastic Upper Convected Maxwell model. We obtain the swimming\nvelocity and hydrodynamic force exerted on an infinitely long cylinder with\nprescribed beating pattern. We use these results to examine the swimming of a\nsimplified sliding-filament model for a sperm flagellum. Viscoelasticity tends\nto decrease swimming speed, and changes in the beating patterns due to\nviscoelasticity can reverse swimming direction.",
        "positive": "Thermal and active fluctuations of a compressible bilayer vesicle: We discuss thermal and active fluctuations of a compressible bilayer vesicle\nby using the results of hydrodynamic theory for vesicles. Coupled Langevin\nequations for the membrane deformation and the density fields are employed to\ncalculate the power spectral density matrix of membrane fluctuations. Thermal\ncontribution is obtained by means of the fluctuation dissipation theorem,\nwhereas active contribution is calculated from exponentially decaying time\ncorrelation functions of active random forces. We obtain the total power\nspectral density as a sum of thermal and active contributions. An apparent\nresponse function is further calculated in order to compare with the recent\nmicrorheology experiment on red blood cells. An enhanced response is predicted\nin the low-frequency regime for non-thermal active fluctuations."
    },
    {
        "anchor": "Living on the edge: transfer and traffic of E. coli in a confined flow: We quantitatively study the transport of E. coli near the walls of confined\nmicrofluidic channels, and in more detail along the edges formed by the\ninterception of two perpendicular walls. Our experiments establish the\nconnection between bacteria motion at the flat surface and at the edges and\ndemonstrate the robustness of the upstream motion at the edges. Upstream\nmigration of E. coli at the edges is possible at much larger flow rates\ncompared to motion at the flat surfaces. Interestingly, the bacteria speed at\nthe edges mainly results from collisions between bacteria moving along this\nsingle line. We show that upstream motion not only takes place at the edge but\nalso in an \"edge boundary layer\" whose size varies with the applied flow rate.\nWe quantify the bacteria fluxes along the bottom walls and the edges and show\nthat they result from both the transport velocity of bacteria and the decrease\nof surface concentration with increasing flow rate due to erosion processes. We\nrationalize our findings as a function of the local variations of the shear\nrate in the rectangular channels and hydrodynamic attractive forces between\nbacteria and walls.",
        "positive": "Singular Values, Nematic Disclinations, and Emergent Biaxiality: Both uniaxial and biaxial nematic liquid crystals are defined by\norientational ordering of their building blocks. While uniaxial nematics only\norient the long molecular axis, biaxial order implies local order along three\naxes. As the natural degree of biaxiality and the associated frame, that can be\nextracted from the tensorial description of the nematic order, vanishes in the\nuniaxial phase, we extend the nematic director to a full biaxial frame by\nmaking use of a singular value decomposition of the gradient of the director\nfield instead. New defects and degrees of freedom are unveiled and the\nsimilarities and differences between the uniaxial and biaxial phase are\nanalyzed by applying the algebraic rules of the quaternion group to the\nuniaxial phase."
    },
    {
        "anchor": "Note: A replica liquid theory of binary mixtures: It has been known that the binary replica liquid theory (RLT) is inconsistent\nwith its one-component counterpart; In the limit that all atoms are identical,\nthe configurational entropy and thus the glass transition point calculated by\nthe binary RLT differ from those obtained by the one-component RLT. More\nspecifically, an extra composition-dependent term, or the mixing entropy,\nremains finite in the configurational entropy computed by the binary RLT. In\nthis Short Note, we reformulate the RLT in order to resolve this problem.",
        "positive": "Ejection dynamics of a ring polymer out of a nanochannel: We investigate the ejection dynamics of a ring polymer out of a cylindrical\nnanochannel using both theoretical analysis and three dimensional Langevin\ndynamics simulations. The ejection dynamics for ring polymers shows two regimes\nlike for linear polymers, depending on the relative length of the chain\ncompared with the channel. For long chains with length $N$ larger than the\ncritical chain length $N_{c}$, at which the chain just fully occupies the\nnanochannel, the ejection for ring polymers is faster compared with linear\nchains of identical length due to a larger entropic pulling force; while for\nshort chains ($N<N_c$), it takes longer time for ring polymers to eject out of\nthe channel due to a longer distance to be diffused to reach the exit of the\nchannel before experiencing the entropic pulling force. These results can help\nunderstand many biological processes, such as bacterial chromosome segregation."
    },
    {
        "anchor": "Structural criterion for the onset of rigidity in a colloidal gel: Identifying the necessary conditions for the onset of rigidity in a gel\nremains a challenge. It has been suggested that local particle coordination\ncould be used to establish such conditions, but rigid gels occur for various\ncoordination numbers. Combining simulations, oscillatory rheology, and a\npercolation analysis, for particles where the valence can be controlled, we\nfind that the onset of rigidity coincides with the percolation of particles\nwith three or more bonds, which arises after the connectivity percolation. We\nshow that the rigidity results from an interplay of bonding and non-bonding\ninteractions, providing insight into low-valence colloidal gel rigidity.",
        "positive": "Stability of Big Surface Bubbles: Impact of Evaporation and Bubbles Size: Surface bubbles have attracted much interest in the past decades. In this\narticle, we propose to explore the lifetime and thinning dynamics of\ncentimetric surface bubbles. We study the impact of the bubbles size as well as\nthat of the atmospheric humidity through a careful control and systematic\nvariation of the relative humidity in the measuring chamber. We first adress\nthe question of the drainage under saturated water vapor conditions and show\nthat a model including both capillary and gravity driven drainage provides the\nbest prediction for this process. Additionally, unprecedented statistics on the\nbubbles lifetimes confirm experimentally that this parameter is set by\nevaporation to leading order. We make use of a model based on the overall\nthinning dynamics of the thin film and assume a rupture thickness of the order\n10-100 nm to obtain a good representation of these data. For experiments\nconducted far from saturation, the convective evaporation of the bath is shown\nto dominate the overall mass loss in the cap film due to evaporation."
    },
    {
        "anchor": "Axisymmetric versus Non-axisymmetric Vortices in Spinor Bose-Einstein\n  Condensates: The structure and stability of various vortices in F=1 spinor Bose-Einstein\ncondensates are investigated by solving the extended Gross-Pitaevskii equation\nunder rotation. We perform an extensive search for stable vortices, considering\nboth axisymmetric and non-axisymmetric vortices and covering a wide range of\nferromagnetic and antiferromagnetic interactions. The topological defect called\nMermin-Ho (Anderson-Toulouse) vortex is shown to be stable for ferromagnetic\ncase. The phase diagram is established in a plane of external rotation Omega vs\ntotal magnetization M by comparing the free energies of possible vortices. It\nis shown that there are qualitative differences between axisymmetric and\nnon-axisymmetric vortices which are manifested in the Omega- and M-dependences.",
        "positive": "Giant Amplification of Small Perturbations in Frictional Amorphous Solid: Catastrophic events in Nature can be often triggered by small perturbations,\nwith \"remote triggering\" of earthquakes being an important example. Here we\npresent a mechanism for the giant amplification of small perturbations that is\nexpected to be generic in systems whose dynamics is not derivable from a\nHamiltonian. We offer a general discussion of the typical instabilities\ninvolved (being oscillatory with an exponential increase of noise) and examine\nin detail the normal forms that determine the relevant dynamics. The high\nsensitivity to external perturbations is explained for systems with and without\ndissipation. Numerical examples are provided using the dynamics of frictional\ngranular matter. Finally we point out the relationship of the presently\ndiscussed phenomenon to the highly topical issue of \"exceptional points\" in\nquantum models with non-Hermitian Hamiltonians."
    },
    {
        "anchor": "Thermodynamic consistency in variable-level coarse-graining of polymeric\n  liquids: Numerically optimized reduced descriptions of macromolecular liquids often\npresent thermodynamic inconsistency with atomistic level descriptions even if\nthe total correlation function, i.e. the structure, appears to be in agreement.\nAn analytical expression for the effective potential between a pair of\ncoarse-grained units is derived starting from the first-principles\nOrnstein-Zernike equation, for a polymer liquid where each chain is represented\nas a collection of interpenetrating blobs, with a variable number of blobs,\n$n_b$, of size $N_b$. The potential is characterized by a long tail, slowly\ndecaying with characteristic scaling exponent of $N_b^{1/4}$. This general\nresult applies to any coarse-grained model of polymer melts with units larger\nthan the persistence length, highlighting the importance of the long,\nrepulsive, potential tail for the model to correctly predict both structural\nand thermodynamic properties of the macromolecular liquid.",
        "positive": "Dynamics of Viscoelastic Filaments Based on Onsager Principle: When a polymer solution is uniaxially stretched and held fixed at both ends,\nthe solution quickly separates into droplets connected by strings and takes the\nbeads-on-string structure. The string then becomes thinner by capillary forces.\nHere we develop a theoretical framework on viscoelastic fluids based on Onsager\nprinciple, and apply it to the dynamics of viscoelastic filaments. We show that\nthe beads-on-string structure is a thermodynamic quasi-equilibrium state, and\nderive an equation for the coexistence condition in the pseudo-equilibrium\nstate. Using the condition, we solve the evolution equation analytically and\nshow that the string radius and the tensile stress vary exponentially as\npredicted by the classical theory of Entov and Hinch [J. Non-Newtonian Fluid\nMech. 72, 31 (1997)], but the prefactor for the tensile stress is different\nfrom their theory and agrees with the numerical solutions of Clasen et al. [J.\nFluid Mech. 556, 283 (2006)]."
    },
    {
        "anchor": "Angular x-ray cross-correlation analysis (AXCCA): Basic concepts and\n  recent applications to soft matter and nanomaterials: Angular x-ray cross-correlation analysis (AXCCA) is a technique which allows\nquantitative measurement of the angular anisotropy of x-ray diffraction\npatterns and provides insights into the orientational order in the system under\ninvestigation. This method is based on the evaluation of the angular\ncross-correlation function of the scattered intensity distribution on a\ntwo-dimensional (2D) detector and further averaging over many diffraction\npatterns for enhancement of the anisotropic signal. Over the last decade, AXCCA\nwas successfully used to study the anisotropy in various soft matter systems,\nsuch as solutions of anisometric particles, liquid crystals, colloidal\ncrystals, superlattices composed by nanoparticles, etc. This review provides an\nintroduction to the technique and gives a survey of the recent experimental\nwork in which AXCCA in combination with micro- or nanofocused x-ray microscopy\nwas used to study the orientational order in various soft matter systems.",
        "positive": "Bond orientational ordering in liquids: Towards a unified description of\n  water-like anomalies, liquid-liquid transition, glass transition, and\n  crystallization: There are at least three fundamental states of matter, depending upon\ntemperature and pressure: gas, liquid, and solid (crystal). These states are\nseparated by first-order phase transitions between them. In both gas and liquid\nphases the complete translational and rotational symmetry exist, whereas in a\nsolid phase both symmetries are broken. In intermediate phases between liquid\nand solid, which include liquid crystal and plastic crystal phases, only one of\nthe two symmetries is preserved. Among the fundamental states of matter, the\nliquid state is most poorly understood. We argue that it is crucial for a\nbetter understanding of liquid to recognize that a liquid generally has a\ntendency to have local structural order and its presence is intrinsic and\nuniversal to any liquid. Such structural ordering is a consequence of many body\ncorrelations, more specifically, bond angle correlations, which we believe are\ncrucial for the description of the liquid state. We show that this physical\npicture may naturally explain difficult unsolved problems associated with the\nliquid state, such as anomalies of water-type liquids (water, Si, Ge, ...),\nliquid-liquid transition, liquid-glass transition, crystallization and\nquasicrystal formation, in a unified manner. In other words, we need a new\norder parameter representing low local free-energy configuration, which is bond\norientational order parameter in many cases, in addition to density order\nparameter for the physical description of these phenomena. Here we review our\ntwo-order-parameter model of liquid and consider how transient local structural\nordering is linked to all of the above-mentioned phenomena. The relationship\nbetween these phenomena are also discussed."
    },
    {
        "anchor": "Temperature dependence of the slip length in polymer melts at attractive\n  surfaces: Using Couette and Poiseuille flow, we extract the temperature dependence of\nthe slip length, $\\delta$, from molecular dynamics simulations of a\ncoarse-grained polymer model in contact with an attractive, corrugated surface.\n$\\delta$ is dictated by the ratio of bulk viscosity and surface mobility. At\nweakly attractive surfaces, a lubrication layer forms, $\\delta$ is large and\nincreases upon cooling. Close to the glass transition temperature, $T_ g$, very\nlarge slip lengths are observed. At a more attractive surface, a``stick y\nsurface layer\" is build up, which gives rise to a small slip length. Upon cool\ning, $\\delta$ decreases at high temperatures, passes through a minimum and\ngrows upon approaching $T_g$. At strongly attractive surfaces, the Navier-slip\ncondit ion fails to describe Couette and Poiseuille flow simultaneously. The\nsimulation results are corroborated by a schematic, two-layer model suggesting\nthat the ob servations do not depend on the details of the computational model.",
        "positive": "New structural anomaly induced by nanoconfinement: We explore the structural properties of anomalous fluids confined in a\nnanopore using Molecular Dynamics simulations. The fluid is modeled by\ncore-softened (CS) potentials that have a repulsive shoulder and an attractive\nwell at a further distance. Changing the attractive well depth of the\nfluid-fluid interaction potential, we studied the behavior of the anomalies in\nthe translational order parameter $t$ and excess entropy $s_{ex}$ for the\nparticles near to the nanopore wall (contact layer) for systems with two or\nthree layers of particles. When the attractive well of the CS potential is\nshallow, the systems present a three to two layers transition and, additionally\nto the usual structural anomaly, a new anomalous region in $t$ and $s_{ex}$.\nFor attractive well deep enough, the systems change from three layers to a\nbulk-like profile and just one region of anomaly in $t$ and $s_{ex}$ is\nobserved. Our results are discussed in the basis of the fluid-fluid and\nfluid-surface interactions."
    },
    {
        "anchor": "Diffusion between evolving interfaces: Diffusion in an evolving environment is studied by continuos-time Monte Carlo\nsimulations. Diffusion is modelled by continuos-time random walkers on a\nlattice, in a dynamic environment provided by bubbles between two\none-dimensional interfaces driven symmetrically towards each other. For\none-dimensional random walkers constrained by the interfaces, the bubble size\ndistribution domi- nates diffusion. For two-dimensional random walkers, it is\nalso controlled by the topography and dynamics of the interfaces. The results\nof the one-dimensional case are recovered in the limit where the interfaces are\nstrongly driven. Even with simple hard-core repulsion between the interfaces\nand the particles, diffusion is found to depend strongly on the details of the\ndynamical rules of particles close to the interfaces. Article reference:\nJournal of Physics: Condensed Matter 22, 465402 (2010).",
        "positive": "Diffusion constant for the repton model of gel electrophoresis: The repton model is a simple model of the \"reptation\" motion by which DNA\ndiffuses through a gel during electrophoresis. In this paper we show that the\nmodel can be mapped onto a system consisting of two types of particles with\nhard-sphere interactions diffusing on a one-dimensional lattice. Using this\nmapping we formulate an efficient Monte Carlo algorithm for the model which\nallows us to simulate systems more than twice the size of those studied before.\nOur results confirm scaling hypotheses which have previously been put forward\nfor the model. We also show how the particle version of the model can be used\nto construct a transfer matrix which allows us to solve exactly for the\ndiffusion constant of small repton systems. We give results for systems of up\nto 20 reptons."
    },
    {
        "anchor": "Electrostatic Self-assembly : A New Route Towards Nanostructures: During the last 3 years, our group has investigated extensively the\ncomplexation mechanism between neutral-polyelectrolyte block copolymers with\noppositely charged species. These species are surfactant micelles, multivalent\ncounterions and inorganic nanoparticles. In the three cases, we have\nestablished the thermodynamical phase diagram of these systems, and found broad\nregions where supramolecular aggregates spontaneously form via electrostatic\nself-assembly. From earlier works, it was suspected that these mixed colloids\nexhibit a core-shell structure. However, their inner structure was unveiled by\nus only recently, using a combination of light, neutron and x-ray scattering\nexperiments.",
        "positive": "Two approaches to quantification of force networks in particulate\n  systems: The interactions between particles in particulate systems are organized in\n`force networks', mesoscale features that bridge between the particle scale and\nthe scale of the system as a whole. While such networks are known to be crucial\nin determining the system wide response, extracting their properties,\nparticularly from experimental systems, is difficult due to the need to measure\nthe interparticle forces. In this work, we show by analysis of the data\nextracted from simulations that such detailed information about interparticle\nforces may not be necessary, as long as the focus is on extracting the most\ndominant features of these networks. The main finding is that a reasonable\nunderstanding of the time evolution of force networks can be obtained from\nincomplete information such as total force on the particles. To compare the\nevolution of the networks based on the completely known particle interactions\nand the networks based on incomplete information (total force each grain) we\nuse tools of algebraic topology. In particular we will compare simple measures\ndefined on persistence diagrams that provide useful summaries of the force\nnetwork features."
    },
    {
        "anchor": "Connectivity dynamics in the vitrification of colloidal liquids: While various structural and dynamical precursors to vitrification have been\nidentified, a predictive and quantitative description of how subtle changes at\nthe microscopic scale give rise to the steep growth in macroscopic viscosity is\nmissing. It was proposed that the presence of long-lived bonded structures\nwithin the liquid may provide this connection. Here we directly observe and\nquantify the connectivity dynamics in liquids of charged colloids en-route to\nvitrification. Based on these data, we extend Dyre's elastic model for the\nglass transition to account for particle-level dynamics; this results in a\nparameter-free expression for the slowing down of relaxations in the liquid\nthat is in quantitative agreement with our experiments.",
        "positive": "Three-phase contact line and line tension of electrolyte solutions in\n  contact with charged substrates: The three-phase contact line formed by the intersection of a liquid-vapor\ninterface of an electrolyte solution with a charged planar substrate is studied\nin terms of classical density functional theory applied to a lattice model. The\ninfluence of the substrate charge density and of the ionic strength of the\nsolution on the intrinsic structure of the three-phase contact line and on the\ncorresponding line tension is analyzed. We find a negative line tension for all\nvalues of the surface charge density and of the ionic strength considered. The\nstrength of the line tension decreases upon decreasing the contact angle via\nvarying either the temperature or the substrate charge density."
    },
    {
        "anchor": "Structure, diffusion and orientational freezing in lithium metasilicate: We report on the dynamic and structural characterization of lithium\nmetasilicate $Li_2SiO_3$, a network forming ionic glass, by means of molecular\ndynamics simulations. The system is characterized by a network of $SiO_4$\ntetrahedra disrupted by $Li$ ions which diffuse through the network. Measures\nof mean square displacement of $Si$ and $O$ atoms allow us to identify a\ntemperature at which tetrahedra stop moving relative to each other. This\ntemperature $T_c\\approx 1500\\,K$ can be characterized within the framework of\nmode coupling theory. At a much lower temperature $T_g\\approx 1000\\,K$, a\nchange in the slope of the volume versus temperature data allows to single out\nthe glass transition. We find signatures of both transitions in structural\norder parameters, related to the orientation of tetrahedra. Going down in\ntemperature we find that, around the mode coupling transition temperature, a\nset of order parameters which measure the relative orientation of tetrahedra\ncease to increase and stay constant below $T_c$. Another well known measure of\norientational order, the bond orientational order parameter, which in the\nstudied system measures local order within single tetrahedrons, is found to\ncontinue growing below $T_c$ until $T_g$, below which it remains constant. Our\nresults allow to relate two characteristic dynamic transitions with\ncorresponding structural transitions, as observed in two different\norientational order parameters. Furthermore, the results indicate that the\nnetwork of thetrahedra continue to relax well below the point where neighboring\ntetrahedra cannot rearrange relative to each other, and the glass is reached\nonly upon a process of relaxation of atoms which form the thetrahedron, as\nquantified by the change in the bond orientational order parameters.",
        "positive": "Migration of chemotactic bacteria in soft agar: role of gel\n  concentration: We study the migration of chemotactic wild-type Escherichia coli populations\nin semisolid (soft) agar in the concentration range C = 0.15-0.5% (w/v). For C\n< 0.35%, expanding bacterial colonies display characteristic chemotactic rings.\nAt C = 0.35%, however, bacteria migrate as broad circular bands rather than\nsharp rings. These are growth/diffusion waves arising because of suppression of\nchemotaxis by the agar and have not been previously reported experimentally to\nour knowledge. For C = 0.4-0.5%, expanding colonies do not span the depth of\nthe agar and develop pronounced front instabilities. The migration front speed\nis weakly dependent on agar concentration at C < 0.25%, but decreases sharply\nabove this value. We discuss these observations in terms of an extended\nKeller-Segel model for which we derived novel transport parameter expressions\naccounting for perturbations of the chemotactic response by collisions with the\nagar. The model makes it possible to fit the observed front speed decay in the\nrange C = 0.15-0.35%, and its solutions qualitatively reproduce the observed\ntransition from chemotactic to growth/diffusion bands. We discuss the\nimplications of our results for the study of bacteria in porous media and for\nthe design of improved bacteriological chemotaxis assays."
    },
    {
        "anchor": "Lattice model of linear telechelic polymer melts. II. Influence of chain\n  stiffness on basic thermodynamic properties: The lattice cluster theory (LCT) for semiflexible linear telechelic melts,\ndeveloped in paper I, is applied to examine the influence of chain stiffness on\nthe average degree of self-assembly and the basic thermodynamic properties of\nlinear telechelic polymer melts. Our calculations imply that chain stiffness\npromotes self-assembly of linear telechelic polymer melts that assemble on\ncooling when either polymer volume fraction $\\phi$ or temperature $T$ is high,\nbut opposes self-assembly when both $\\phi$ and $T$ are sufficiently low. This\nallows us to identify a boundary line in the $\\phi$-$T$ plane that separates\ntwo regions of qualitatively different influence of chain stiffness on\nself-assembly. The enthalpy and entropy of self-assembly are usually treated as\nadjustable parameters in classical Flory-Huggins type theories for the\nequilibrium self-assembly of polymers, but they are demonstrated here to\nstrongly depend on chain stiffness. Moreover, illustrative calculations for the\ndependence of the entropy density of linear telechelic polymer melts on chain\nstiffness demonstrate the importance of including semiflexibility within the\nLCT when exploring the nature of glass formation in models of linear telechelic\npolymer melts.",
        "positive": "Hyperuniformity Disorder Length Spectroscopy for Extended Particles: The concept of a hyperuniformity disorder length $h$ was recently introduced\nfor analyzing volume fraction fluctuations for a set of measuring windows. This\nlength permits a direct connection to the nature of disorder in the spatial\nconfiguration of the particles, and provides a way to diagnose the degree of\nhyperuniformity in terms of the scaling of $h$ and its value in comparison with\nestablished bounds. Here, this approach is generalized for extended particles,\nwhich are larger than the image resolution and can lie partially inside and\npartially outside the measuring windows. The starting point is an expression\nfor the volume fraction variance in terms of four distinct volumes: that of the\nparticle, the measuring window, the mean-squared overlap between particle and\nregion, and the region over which particles have non-zero overlap with the\nmeasuring window. After establishing limiting behaviors, computational methods\nare developed for both continuum and pixelated particles. Exact results are\npresented for particles of special shape, and for measuring windows of special\nshape. Comparison is made for other particle shapes, using simulated Poisson\npatterns. And the effects of polydisersity and image errors are discussed. For\nsmall measuring windows, both particle shape and spatial arrangement affect the\nform of the variance. For large regions, the variance scaling depends only on\narrangement but particle shape sets the numerical proportionality. The combined\nunderstanding permit the measured variance to be translated to the spectrum of\nhyperuniformity lengths versus region size, as the quantifier of spatial\narrangement. This program is demonstrated for a system of non-overlapping\nparticles at a series of increasing packing fractions as well as for an\nEinstein pattern of particles with several different extended shapes."
    },
    {
        "anchor": "Ion clustering in aqueous salt solutions near the liquid/vapor interface: Molecular dynamics simulations of aqueous NaCl, KCl, NaI, and KI solutions\nare used to study the effects of salts on the properties of the liquid/vapor\ninterface. The simulations use the models which include both charge transfer\nand polarization effects. Pairing and the formation of larger ion clusters\noccurs both in the bulk and surface region, with a decreased tendency to form\nlarger clusters near the interface. An analysis of the roughness of the surface\nreveals that the chloride salts, which have less tendency to be near the\nsurface, have a roughness that is less than pure water, while the iodide salts,\nwhich have a greater surface affinity, have a larger roughness. This suggests\nthat ions away from the surface and ions near the surface affect the interface\nin opposite ways.",
        "positive": "Universal behavior in fragmenting brittle, isotropic solids across\n  material properties: A bonded particle model is used to explore how variations in the material\nproperties of brittle, isotropic solids affect critical behavior in\nfragmentation. To control material properties, a new model is proposed which\nincludes breakable two- and three-body particle interactions to calibrate\nelastic moduli and mode I and II fracture toughnesses. In the quasistatic\nlimit, fragmentation leads to a power-law distribution of grain sizes which is\ntruncated at a maximum grain mass that grows as a non-trivial power of system\nsize. In the high-rate limit, truncation occurs at a mass that decreases as a\npower of increasing rate. A scaling description is used to characterize this\nbehavior by collapsing the mean squared grain mass across rates and system\nsizes. Consistent scaling persists across all material properties studied\nalthough there are differences in the evolution of grain size distributions\nwith strain as the initial number of grains at fracture and their subsequent\nrate of production depend on Poisson's ratio. This evolving granular structure\nis found to induce a unique rheology where the ratio of the shear stress to\npressure, an internal friction coefficient, decays approximately as the\nlogarithm of increasing strain rate. The stress ratio also decreases at all\nrates with increasing strain as fragmentation progresses."
    },
    {
        "anchor": "Wetting-induced effective interaction potential between spherical\n  particles: Using a density functional based interface displacement model we determine\nthe effective interaction potential between two spherical particles which are\nimmersed in a homogeneous fluid such as the vapor phase of a one-component\nsubstance or the A-rich liquid phase of a binary liquid mixture composed of A\nand B particles. If this solvent is thermodynamically close to a first-order\nfluid-fluid phase transition, the spheres are covered with wetting films of the\nincipient bulk phase, i.e., the liquid phase or the B-rich liquid,\nrespectively. Below a critical distance between the spheres their wetting films\nsnap to a bridgelike configuration. We determine phase diagrams for this\nmorphological transition and analyze its repercussions on the effective\ninteraction potential. Our results are accessible to force microscopy and may\nbe relevant to flocculation in colloidal suspensions.",
        "positive": "Likelihood of survival of coronavirus in a respiratory droplet deposited\n  on a solid surface: We predict and analyze the drying time of respiratory droplets from a\nCOVID-19 infected subject, which is a crucial time to infect another subject.\nThe drying of the droplet is predicted by diffusion-limited evaporation model\nfor a sessile droplet placed on a partially-wetted surface with a pinned\ncontact line. The variation of droplet volume, contact angle, ambient\ntemperature, and humidity are considered. We analyze the chances of the\nsurvival of the viruses present in the droplet, based on the lifetime of the\ndroplets in several conditions, and find that the chances of survival of the\nvirus are strongly affected by each of these parameters. The magnitude of shear\nstress inside the droplet computed using the model is not large enough to\nobliterate the virus. We also explore the relationship between the drying time\nof a droplet and the growth rate of the spread of COVID-19 for five different\ncities, and find that they are weakly correlated."
    },
    {
        "anchor": "Phase behavior and interfacial properties of nonadditive mixtures of\n  Onsager rods: Within a second virial theory, we study bulk phase diagrams as well as the\nfree planar isotropic-nematic interface of binary mixtures of nonadditive thin\nand thick hard rods. For species of the same type the excluded volume is\ndetermined only by the dimensions of the particles, whereas for dissimilar ones\nit is taken to be larger or smaller than that, giving rise to a nonadditivity\nthat can be positive or negative. We argue that such a nonadditivity can result\nfrom modelling of soft interactions as effective hard-core interactions. The\nnonadditivity enhances or reduces the fractionation at isotropic-nematic ($IN$)\ncoexistence and may induce or suppress a demixing of the high-density nematic\nphase into two nematic phases of different composition ($N_1$ and $N_2$),\ndepending on whether the nonadditivity is positive or negative. The interfacial\ntension between co-existing isotropic and nematic phases show an increase with\nincreasing fractionation at the $IN$ interface, and complete wetting of the\n$IN_2$ interface by the $N_1$ phase upon approach of the triple point\ncoexistence. In all explored cases bulk and interfacial properties of the\nnonadditive mixtures exhibit a striking and quite unexpected similarity with\nthe properties of additive mixtures of different diameter ratio.",
        "positive": "Steady vs. Dynamic Contributions of Different Doped Conducting Polymers\n  in the Principal Components of an Electronic Nose's Response: Multivariate data analysis and machine-learning classification become popular\ntools to extract features without physical models for complex environments\nrecognition. For electronic noses, time sampling over multiple sensors must be\na fair compromise between a period sufficiently long to output a meaningful\ninformation pattern, and sufficiently short to minimize training time for\npractical applications. Particularly when reactivity's kinetics differ from\nthermodynamics' in sensitive materials, finding the best compromise to get the\nmost from data is not obvious. Here, we investigate on the influence of data\nacquisition to improve or alter data clustering for molecular recognition on a\nconducting polymer electronic nose. We found out that waiting for the sensors\nto reach their steady state is not required for classification, and that\nreducing data acquisition down to the first dynamical information suffice to\nrecognize molecular gases by principal component analysis with the same\nmaterials. Particularly for online inference, this study shows that a good\nsensing array is no array of good sensors, and that new figure-of-merits shall\nbe defined for sensing hardware aiming machine-learning pattern-recognition\nrather than metrology."
    },
    {
        "anchor": "Effect of glycerol and dimethyl sulfoxide on the phase behavior of\n  lysozyme: Theory and experiments: Salt, glycerol and dimethyl sulfoxide (DMSO) are used to modify the\nproperties of protein solutions. We experimentally determined the effect of\nthese additives on the phase behavior of lysozyme solutions. Upon the addition\nof glycerol and DMSO, the fluid-solid transition and the gas-liquid coexistence\ncurve (binodal) shift to lower temperatures and the gap between them increases.\nThe experimentally observed trends are consistent with our theoretical\npredictions based on the thermodynamic perturbation theory (TPT) and the\nDerjaguin-Landau-Verwey-Overbeek (DLVO) model for the lysozyme-lysozyme pair\ninteractions. The values of the parameters describing the interactions, namely\nthe refractive indices, dielectric constants, Hamaker constant and cut-off\nlength, are extracted from literature or are experimentally determined by\nindependent experiments, including static light scattering to determine the\nsecond virial coefficient. We observe that both, glycerol and DMSO, render the\npotential more repulsive, while sodium chloride reduces the repulsion.",
        "positive": "Reversal of Helicoidal Twist Handedness Near Point Defects of Confined\n  Chiral Liquid Crystals: Handedness of the director twist in cholesteric liquid crystals is commonly\nassumed to be the same throughout the medium, determined solely by the\nchirality of constituent molecules or chiral additives, albeit distortions of\nthe ground-state helicoidal configuration often arise due to the effects of\nconfinement and external fields. We directly probe the twist directionality of\nliquid crystal director structures through experimental three-dimensional\nimaging and numerical minimization of the elastic free energy and show that\nspatially localized regions of handedness opposite to that of the chiral liquid\ncrystal ground state can arise in the proximity of twisted-soliton-bound\ntopological point defects. In chiral nematic liquid crystal confined to a film\nthat has a thickness less than the cholesteric pitch and perpendicular surface\nboundary conditions, twisted solitonic structures embedded in a uniform unwound\nfar-field background with chirality-matched handedness locally relieve\nconfinement-imposed frustration and tend to be accompanied by point defects and\nsmaller geometry-required energetically costly regions of opposite twist\nhandedness. We also describe a new spatially localized structure, dubbed a\n\"twistion\", in which a twisted solitonic three-dimensional director\nconfiguration is accompanied by four point defects. We discuss how our findings\nmay impinge on the stability of localized particle-like director field\nconfigurations in chiral and non-chiral liquid crystals."
    },
    {
        "anchor": "Wetting behaviour of a three-phase system in contact with a surface: We extend the Cahn-Landau-de Gennes mean field theory of binary mixtures to\nunderstand the wetting thermodynamics of a three phase system, that is in\ncontact with an external surface which prefers one of the phases. We model the\nsystem using a phenomenological free energy having three minima corresponding\nto low, intermediate and high density phases. By systematically varying the\n\\textit{(i)} depth of the central minimum, \\textit{(ii)} the surface\ninteraction parameters, we explore the phase behavior, and wetting\ncharacteristics of the system across the triple point corresponding to three\nphase coexistence. We observe a non-monotonic dependence of the surface tension\nacross the triple point that is associated with a complete to partial wetting\ntransition. The methodology is then applied to study the wetting behaviour of a\npolymer-liquid crystal mixture in contact with a surface using a renormalised\nfree energy. Our work provides a way to interrogate phase behavior and wetting\ntransitions of biopolymers in cellular environments.",
        "positive": "Nanofriction on Sodium Polystyrene Sulfonate Brushes in Water: We investigated the frictional properties of sodium polystyrene sulfonate\n(NaPSS) brushes in water by frictional force microscopy (FFM). Polyelectrolyte\nbrushes were prepared on silicon wafers by the grafting-to method. The brushes\nconsiderably reduce the frictional force and coefficient of kinetic friction\ncompared to hydrodynamic lubrication on a smooth Si wafer. Frictional force is\nindependent of sliding speed, but is lower for lower degrees of NaPSS\npolymerization. Nanoindentation tests indicate that the polymer chains in a\nbrush are stretched strongly away from the substrate. These results suggest\nthat polymer chains point support the FFM probe tip in water and reduced\ncontact area and friction."
    },
    {
        "anchor": "II. Geometrical framework for thinking about globular proteins: the\n  power of poking: Recently, we presented a framework for understanding protein structure based\non the idea that simple constructs of holding hands or touching of objects can\nbe used to rationalize the common characteristics of globular proteins. We\ndeveloped a consistent approach for understanding the formation of the two key\ncommon building blocks of helices and sheets as well as the compatible assembly\nof secondary structures into the tertiary structure through the notion of\npoking pairwise interactions. Here we benchmark our predictions with a detailed\nanalysis of structural data of over 4000 proteins from the Protein Data Bank.\nWe also present the results of detailed computer simulations of a simplified\nmodel demonstrating a pre-sculpted free energy landscape, determined by\ngeometry and symmetry, comprising numerous minima corresponding to putative\nnative state structures. We explore the consequences of our model. Our results\nsuggest that symmetry and geometry are a powerful guide to capture the\nsimplicity underlying protein complexity.",
        "positive": "Lattice Boltzmann simulations of phase separation in chemically reactive\n  binary fluids: We use a lattice Boltzmann method to study pattern formation in chemically\nreactive binary fluids in the regime where hydrodynamic effects are important.\nThe coupled equations solved by the method are a Cahn-Hilliard equation,\nmodified by the inclusion of a reactive source term, and the Navier-Stokes\nequations for conservation of mass and momentum. The coupling is two-fold,\nresulting from the advection of the order-parameter by the velocity field and\nthe effect of fluid composition on pressure. We study the the evolution of the\nsystem following a critical quench for a linear and for a quadratic reaction\nsource term. Comparison is made between the high and low viscosity regimes to\nidentify the influence of hydrodynamic flows. In both cases hydrodynamics is\nfound to influence the pathways available for domain growth and the eventual\nsteady-states."
    },
    {
        "anchor": "How Glassy Relaxation Slows Down by Increasing Mobility: We investigate how structural relaxation in mixtures with strong dynamical\nasymmetry is affected by the microscopic dynamics. Brownian and Newtonian\ndynamics simulations of dense mixtures of fast and slow hard spheres reveal a\nstriking trend reversal. Below a critical density, increasing the mobility of\nthe fast particles fluidizes the system, yet, above that critical density, the\nsame increase in mobility strongly hinders the relaxation of the slow\nparticles. The critical density itself does not depend on the dynamical\nasymmetry and can be identified with the glass-transition density of the\nmode-coupling theory. The asymptotic dynamics close to the critical density is\nuniversal, but strong pre-asymptotic effects prevail in mixtures with\nadditional size asymmetry. This observation reconciles earlier findings of a\nstrong dependence on kinetic parameters of glassy dynamics in colloid--polymer\nmixtures with the paradigm that the glass transition is determined by the\nproperties of configuration space alone.",
        "positive": "Programmable Mechanical Metamaterials: the Role of Geometry: We experimentally and numerically study the precise role of geometry for the\nmechanics of biholar metamaterials, quasi-2D slabs of rubber patterned by\ncircular holes of two alternating sizes. We recently showed how the response to\nuniaxial compression of these metamaterials can be programmed by their lateral\nconfinement $^1$. In particular, there is a range of confining strains\n$\\varepsilon_x$ for which the resistance to compression becomes non-trivial -\nnon-monotonic or hysteretic - in a range of compressive strains\n$\\varepsilon_y$. Here we show how the dimensionless geometrical parameters $t$\nand $\\chi$, which characterize the porosity and size ratio of the holes that\npattern these metamaterials, can significantly tune these ranges over a wide\nrange. We study the behavior for the limiting cases where $t$ and $\\chi$ become\nlarge, and discuss the new physics that arises there. Away from these extreme\nlimits, the variation of the strain ranges of interest is smooth with porosity,\nbut the variation with size ratio evidences a cross-over at low $\\chi$ from\nbiholar to monoholar (equal sized holes) behavior, related to the elastic\ninstabilities in purely monoholar metamaterials$^2$. Our study provides precise\nguidelines for the rational design of programmable biholar metamaterials,\ntailored to specific applications, and indicates that the widest range of\nprogrammability arises for moderate values of both $t$ and $\\chi$."
    },
    {
        "anchor": "Swimming path statistics of an active Brownian particle with\n  time-dependent self-propulsion: Typically, in the description of active Brownian particles, a constant\neffective propulsion force is assumed, which is then subjected to fluctuations\nin orientation and translation leading to a persistent random walk with an\nenlarged long-time diffusion coefficient. Here, we generalize previous results\nfor the swimming path statistics to a time-dependent and thus in many\nsituations more realistic propulsion which is a prescribed input. We\nanalytically calculate both the noise-free and the noise-averaged trajectories\nfor time-periodic propulsion under the action of an additional torque. In the\ndeterministic case, such an oscillatory microswimmer moves on closed paths that\ncan be highly more complicated than the commonly observed straight lines and\ncircles. When exposed to random fluctuations, the mean trajectories turn out to\nbe self-similar curves which bear the characteristics of their noise-free\ncounterparts. Furthermore, we consider a propulsion force which scales in time\n$t$ as $\\propto \\! t^\\alpha$ (with $\\alpha=0,1,2,\\ldots$) and analyze the\nresulting superdiffusive behaviour. Our predictions are verifiable for\ndiffusiophoretic artificial microswimmers with prescribed propulsion protocols.",
        "positive": "Interfacial Phenomena of Solvent-diluted Block Copolymers: A phenomenological mean-field theory is used to investigate the properties of\nsolvent-diluted di-block copolymers (BCP), in which the two BCP components (A\nand B) form a variety of phases that are diluted by a solvent (S). Using this\napproach, we model mixtures of di-block copolymers and a solvent and obtained\nthe corresponding critical behavior. In the low solvent limit, we find how the\ncritical point depends on the solvent density. Due to the non-linear nature of\nthe coupling between the A/B and BCP/solvent concentrations, the A/B modulation\ninduces modulations in the polymer-solvent relative concentration with a double\nwavenumber. The free boundary separating the polymer-rich phase from the\nsolvent-rich one is studied in two situations. First, we show how the presence\nof a chemically patterned substrate leads to deformations of the BCP\nfilm/solvent interface, creation of terraces in lamellar BCP film and even\nformation of multi-domain droplets as induced by the patterned substrate. Our\nresults are in agreement with previous self-consistent field theory\ncalculations. Second, we compare the surface tension between parallel lamellae\ncoexisting with a solvent phase with that of a perpendicular one, and show that\nthe surface tension has a non-monotonic dependence on temperature. The\nanisotropic surface tension can lead to deformation of spherical BCP droplets\ninto lens-shaped ones, together with re-orientation of the lamellae inside the\ndroplet during the polymer/solvent phase separation process in agreement with\nexperiment."
    },
    {
        "anchor": "Spontaneous Charging and Crystallization of Water Droplets in Oil: We study the spontaneous charging and the crystallization of spherical\nmicron-sized water-droplets dispersed in oil by numerically solving, within a\nPoisson-Boltzmann theory in the geometry of a spherical cell, for the density\nprofiles of the cations and anions in the system. We take into account\nscreening, ionic Born self-energy differences between oil and water, and\npartitioning of ions over the two media. We find that the surface charge\ndensity of the droplet as induced by the ion partitioning is significantly\naffected by the droplet curvature and by the finite density of the droplets. We\nalso find that the salt concentration and the dielectric constant regime in\nwhich crystallization of the water droplets is predicted is enhanced\nsubstantially compared to results based on the planar oil-water interface,\nthereby improving quantitative agreement with recent experiments.",
        "positive": "Percolation transition of pusher-type microswimmers: We identify the presence of a continuum percolation transition in model\nsuspensions of pusher-type microswimmers. The clusters dynamically aggregate\nand disaggregate resulting from a competition of attractive and repulsive\nhydrodynamic and steric interactions. As the microswimmers' filling fraction\nincreases, the cluster size distribution approaches a scale-free form and there\nemerge large clusters spanning the entire system. We characterize this\nmicroswimmer percolation transition via the critical exponents associated to\ncluster size distribution $\\tau$, correlation length $\\nu$, mean cluster size\n$\\gamma$, and clusters' fractal dimension $d_f$. We are able to show that two\nscaling relations, known from percolation theory, also hold for our\nmicroswimmers. A real-space renormalization group transformation can\napproximately predict the value of the exponent $\\nu$. This finding opens new\nvistas on microswimmers' congregative processes."
    },
    {
        "anchor": "Glasslike Arrest in Spinodal Decomposition as a Route to Colloidal\n  Gelation: Colloid-polymer mixtures can undergo spinodal decomposition into colloid-rich\nand colloid-poor regions. Gelation results when interconnected colloid-rich\nregions solidify. We show that this occurs when these regions undergo a glass\ntransition, leading to dynamic arrest of the spinodal decomposition. The\ncharacteristic length scale of the gel decreases with increasing quench depth,\nand the nonergodicity parameter exhibits a pronounced dependence on scattering\nvector. Mode coupling theory gives a good description of the dynamics, provided\nwe use the full static structure as input.",
        "positive": "How to unloop a self-adherent sheet: The mechanics of adherent sheets is central to applications ranging from\npatching a band aid, coating technology, to the breakthrough discovery of\npeeling graphene flakes using sticky tape. These processes are often hindered\nby the formation of blisters and loops, which are notoriously difficult to\nremove. Here we describe and explain a remarkable phenomenon that arises when\none attempts to remove a loop in a self-adherent sheet that is formed by, e.g.,\nfolding two adhesive sides of a tape together. One would expect the loop to\nsimply unloop when pulling on its free ends. Surprisingly, however, the loop\ndoes not immediately open up but shrinks in size, held together by a tenuous\ncontact region that propagates along the tape. This adhesive contact region\nonly ruptures once the loop is reduced to a critical size. We experimentally\nshow that the loop-shrinkage results from an interaction between the peeling\nfront and the loop, across the contact zone. This new type of interaction falls\noutside the realm of the classical elastica theory and is responsible for a\nhighly nonlinear increase in the peeling force. Our results reveal and quantify\nthe increased force required to remove loops in self-adherent media, which is\nof importance for blister removal and exfoliation of graphene sheets."
    },
    {
        "anchor": "Entropy and Kinetics of Point-Defects in Two-Dimensional Dipolar\n  Crystals: We study in experiment and with computer simulation the free energy and the\nkinetics of vacancy and interstitial defects in two-dimensional dipolar\ncrystals. The defects appear in different local topologies which we\ncharacterize by their point group symmetry; $C_n$ is the n-fold cyclic group\nand $D_n$ is the dihedral group, including reflections. The frequency of\ndifferent local topologies is not determined by their almost degenerate\nenergies but dominated by entropy for symmetric configurations. The kinetics of\nthe defects is fully reproduced by a master equation in a multi-state Markov\nmodel. In this model, the system is described by the state of the defect and\nthe time evolution is given by transitions occurring with particular rates.\nThese transition rate constants are extracted from experiments and simulations\nusing an optimisation procedure. The good agreement between experiment,\nsimulation and master equation thus provides evidence for the accuracy of the\nmodel.",
        "positive": "Capturing the helical to spiral transitions in thin ribbons of nematic\n  elastomers: We provide a quantitative description of the helicoid--to--spiral transition\nin thin ribbons of nematic elastomers using an elementary calculation based on\na Koiter-type plate with incompatible reference configuration. Our calculation\nconfirms that such transition is ruled by the competition between stretching\nenergy and bending energy."
    },
    {
        "anchor": "Designing an Optimal Ion Adsorber at the Nanoscale: The Unusual\n  Nucleation of AgNP/Co$^{2+}$ -- Ni$^{2+}$ Binary Mixtures: Selective removal of heavy metals from water is a complex topic. We present a\ntheoretical computational approach, supported by experimental evidences, to\ndesign a functionalized nanomaterial that is able to selectively capture\nmetallic ions from water in a self-assembling process. A theoretical model is\nused to map an experimental mixture of Ag nanoparticles and either Co$^{2+}$ or\nNi$^{2+}$ onto an additive highly asymmetric attractive Lennard Jones binary\nmixture. Extensive NVT (constant number of particles, volume, and temperature)\nMonte Carlo simulations are performed to derive a set of parameters that first\ninduce aggregation among the two species in solution and then affect the\nmorphology of the aggregates. The computational predictions are thus compared\nwith the experimental results. The gathered insights can be used as guidelines\nfor the prediction of an optimal design of a new generation of selective\nnanoparticles to be used for metallic ion adsorption and hence for maximizing\nthe trapping of ions in an aqueous solution.",
        "positive": "Mechanism for the stabilization of protein clusters above the solubility\n  curve: Pan, Vekilov and Lubchenko[\\textit{J. Phys. Chem. B}, 2010, \\textbf{114},\n7620] have proposed that dense stable protein clusters appearing in weak\nprotein solutions above the solubility curve are composed of protein oligomers.\nThe hypothesis is that a weak solution of oligomer species is unstable with\nrespect to condensation causing the formation of dense, oligomer-rich droplets\nwhich are stabilized against growth by the monomer-oligomer reaction. Here, we\nshow that such a combination of processes can be understood using a simple\ncapillary model yielding analytic expressions for the cluster properties which\ncan be used to interpret experimental data. We also construct a microscopic\nDynamic Density Functional Theory model and show that it is consistent with the\npredictions of the capillary model. The viability of the mechanism is thus\nconfirmed and it is shown how the radius of the stable clusters is related to\nphysically interesting quantities such as the monomer-oligomer rate constants."
    },
    {
        "anchor": "Polar nanoregions in water - a study of the dielectric properties of\n  TIP4P/2005, TIP4P/2005f and TTM3F: We present a critical comparison of the dielectric properties of three models\nof water - TIP4P/2005, TIP4P/2005f and TTM3F. Dipole spatial correlation is\nmeasured using the distance dependent Kirkwood function along with one\ndimensional and two dimensional dipole correlation functions. We find that the\nintroduction of flexibility alone does not significantly affect dipole\ncorrelation and only affects $\\varepsilon(\\omega)$ at high frequencies. By\ncontrast the introduction of polarizability increases dipole correlation and\nyields a more accurate $\\varepsilon(\\omega)$. Additionally the introduction of\npolarizability creates temperature dependence in the dipole moment even at\nfixed density, yielding a more accurate value for $d \\varepsilon / d T$\ncompared to non-polarizable models. To better understand the physical origin of\nthe dielectric properties of water we make analogies to the physics of polar\nnanoregions in relaxor ferroelectric materials. We show that\n$\\varepsilon(\\omega,T)$ and $\\tau_D(T)$ for water have striking similarities\nwith relaxor ferroelectrics, a class of materials characterized by large\nfrequency dispersion in $\\varepsilon(\\omega,T)$, Vogel-Fulcher-Tamann behaviour\nin $\\tau_D(T)$, and the existence of polar nanoregions.",
        "positive": "Mechanical noise dependent Aging and Shear Banding behavior of a\n  mesoscopic model of amorphous plasticity: We discuss aging and localization in a simple \"Eshelby\" mesoscopic model of\namorphous plasticity. Plastic deformation is assumed to occur through a series\nof local reorganizations. Using a discretization of the mechanical fields on a\ndiscrete lattice, local reorganizations are modeled as local slip events. Local\nyield stresses are randomly distributed in space and invariant in time. Each\nplastic slip event induces a long-ranged elastic stress redistribution.\nMimicking the effect of aging, we focus on the behavior of the model when the\ninitial state is characterized by a distribution of high local yield stress\nvalues. A dramatic effect on the localization behavior is obtained: the system\nfirst spontaneously self-traps to form a shear band which then only slowly\nwidens. The higher the \"age\" parameter the more localized the plastic strain\nfield. Two-time correlation computed on the stress field show a divergent\ncorrelation time with the age parameter. The amplitude of a local slip event\n(the prefactor of the Eshelby singularity) as compared to the yield stress\ndistribution width acts here as an effective temperature-like parameter: the\nlower the slip increment, the higher the localization and the decorrelation\ntime."
    },
    {
        "anchor": "Driven dynamics in dense suspensions of microrollers: We perform detailed computational and experimental measurements of the driven\ndynamics of a dense, uniform suspension of sedimented microrollers driven by a\nmagnetic field rotating around an axis parallel to the floor. We develop a\nlubrication-corrected Brownian Dynamics method for dense suspensions of driven\ncolloids sedimented above a bottom wall. The numerical method adds lubrication\nfriction between nearby pairs of particles, as well as particles and the bottom\nwall, to a minimally-resolved model of the far-field hydrodynamic interactions.\nOur experiments combine fluorescent labeling with particle tracking to trace\nthe trajectories of individual particles in a dense suspension, and to measure\ntheir propulsion velocities. Previous computational studies [B. Sprinkle et\nal., J. Chem. Phys., 147, 244103, 2017] predicted that at sufficiently high\ndensities a uniform suspension of microrollers separates into two layers, a\nslow monolayer right above the wall, and a fast layer on top of the bottom\nlayer. Here we verify this prediction, showing good quantitative agreement\nbetween the bimodal distribution of particle velocities predicted by the\nlubrication-corrected Brownian Dynamics and those measured in the experiments.\nThe computational method accurately predicts the rate at which particles are\nobserved to switch between the slow and fast layers in the experiments. We also\nuse our numerical method to demonstrate the important role that pairwise\nlubrication plays in motility-induced phase separation in dense monolayers of\ncolloidal microrollers, as recently suggested for suspensions of Quincke\nrollers [D. Geyer et al., Physical Review X, 9(3), 031043, 2019].",
        "positive": "Nematic versus ferromagnetic shells: new insights in curvature-induced\n  effects: Within the framework of continuum theory, we draw a parallel between\nferromagnetic materials and nematic liquid crystals confined on curved\nsurfaces, which are both characterized by local interaction and anchoring\npotentials. We show that the extrinsic curvature of the shell combined with the\nout-of-plane component of the director field gives rise to chirality effects.\nThis interplay produces an effective energy term reminiscent of the chiral term\nin cholesteric liquid crystals, with the curvature tensor acting as a sort of\nanisotropic helicity. We discuss also how the different nature of the order\nparameter, a vector in ferromagnets and a tensor in nematics, yields different\ntextures on surfaces with the same topology as the sphere. In particular, we\nshow that the extrinsic curvature governs the ground state configuration on a\nnematic spherical shell, favouring two antipodal disclinations of charge +1 on\nsmall particles and four $+1/2$ disclinations of charge located at the vertices\nof a square inscribed in a great circle on larger particles."
    },
    {
        "anchor": "Bose-Fermi Mixtures in One Dimension: We analyze the phase stability and the response of a mixture of bosons and\nspin-polarized fermions in one dimension (1D). Unlike in 3D, phase separation\nhappens for low fermion densities. The dynamics of the mixture at low energy is\nindependent of the spin-statistics of the components, and zero-sound-like modes\nexist that are essentially undamped.",
        "positive": "Scaling of the Strain Hardening Modulus of Glassy Polymers with the Flow\n  Stress: In a recent letter, Govaert et al. examined the relationship between strain\nhardening modulus $G_r$ and flow stress $\\sigma_{flow}$ for five different\nglassy polymers. In each case, results for $G_r$ at different strain rates or\ndifferent temperatures were linearly related to the flow stress. They suggested\nthat this linear relation was inconsistent with simulations. Data from previous\npublications and new results are presented to show that simulations also yield\na linear relation between modulus and flow stress. Possible explanations for\nthe change in the ratio of modulus to flow stress with temperature and strain\nrate are discussed."
    },
    {
        "anchor": "Experimental Full-field Analysis of Size Effects in Miniaturized\n  Cellular Elastomeric Metamaterials: Cellular elastomeric metamaterials are interesting for various applications,\ne.g. soft robotics, as they may exhibit multiple microstructural pattern\ntransformations, each with its characteristic mechanical behavior. Numerical\nliterature studies revealed that pattern formation is restricted in (thick)\nboundary layers causing significant mechanical size effects. This paper aims to\nexperimentally validate these findings on miniaturized specimens, relevant for\nreal applications, and to investigate the effect of increased geometrical and\nmaterial imperfections resulting from specimen miniaturization. To this end,\nminiaturized cellular metamaterial specimens are manufactured with different\nscale ratios, subjected to in-situ micro-compression tests combined with\ndigital image correlation yielding full-field kinematics, and compared to\ncomplementary numerical simulations. The specimens' global behavior agrees well\nwith the numerical predictions, in terms of pre-buckling stiffness, buckling\nstrain and post-buckling stress. Their local behavior, i.e. pattern\ntransformation and boundary layer formation, is also consistent between\nexperiments and simulations. Comparison of these results with idealized\nnumerical studies from literature reveals the influence of the boundary\nconditions in real cellular metamaterial applications, e.g. lateral\nconfinement, on the mechanical response in terms of size effects and boundary\nlayer formation.",
        "positive": "Solvent-Free High-Temperature Capillary Stamping of Stimuli-Responsive\n  Polymers: Wettability Management by Orthogonal Substrate Functionalization: The wettability of surfaces determines their antifouling, antifogging,\nanti-icing, and self-cleaning properties as well as their usability for\nsensing, oil-water separation, water collection, and water purification.\nSolvent-free high-temperature capillary stamping of stimuli-responsive polymers\nyielding arrays of stimuli-responsive polymer microdots on differently modified\nsubstrates enables the flexible generation of switchable surfaces with\ndifferent water contact angles (WCAs). Potential problems associated with the\ndeposition of polymer solutions, such as the handling of volatile organic\nsolvents, phase separation induced by solvent evaporation, and\ncapillarity-driven flow processes, are circumvented. We used composite stamps\nwith topographically patterned contact surfaces consisting of metallic nickel\ncores and porous MnO2 coatings taking up the stimuli-responsive polymers. The\nshort transport paths from the MnO2 contact layers to the counterpart\nsubstrates enabled the stamping of polymer melts containing components impeding\nflow, such as carbon nanotubes (CNTs). Thus-obtained arrays of polymer-CNT\nhybrid microdots prevent problems associated with continuous coatings including\ndelamination and crack propagation. Moreover, the range within which the\nproperties of the stamped stimuli-responsive polymer microdots are switchable\ncan be tuned by orthogonal substrate modification. As an example, we stamped\nhybrid microdots consisting of poly(2-(methacryloyloxy)ethyl\nferrocenecarboxylate) (PFcMA) and CNTs onto indium tin oxide (ITO) substrates.\nCoating the ITO substrates with a poly(ethylene oxide)-terminated silane\nshifted the WCAs obtained by switching the PFcMA between its oxidized and\nreduced states by nearly 50{\\deg}."
    },
    {
        "anchor": "Density scaling as a property of strongly correlating viscous liquids: We address a recent conjecture according to which the relaxation time $\\tau$\nof a viscous liquid obeys density scaling ($\\tau=F(\\rho^\\gamma/T)$ where $\\rho$\nis density) if the liquid is ``strongly correlating,'' i.e., has almost 100%\ncorrelation between equilibrium virial and potential-energy fluctuations\n[Pedersen {\\it et al.}, PRL {\\bf 100}, 011201 (2008)]. Computer simulations of\ntwo model liquids - an asymmetric dumbbell model and the Lewis-Wahnstr\\\"om OTP\nmodel - confirm the conjecture and demonstrate that the scaling exponent\n$\\gamma$ can be accurately predicted from equilibrium fluctuations.",
        "positive": "Energy required to pinch a DNA plectoneme: DNA supercoiling plays an important role on a biological point of view. One\nof its consequences at the supra-molecular level is the formation of DNA\nsuperhelices named plectonemes. Normally separated by a distance on the order\nof 10 nm, the two opposite double-strands of a DNA plectoneme must be brought\ncloser if a protein or protein complex implicated in genetic regulation is to\nbe bound simultaneously to both strands, as if the plectoneme was locally\npinched. We propose an analytic calculation of the energetic barrier, of\nelastic nature, required to bring closer the two loci situated on the opposed\ndouble-strands. We examine how this energy barrier scales with the DNA\nsupercoiling. For physically relevant values of elastic parameters and of\nsupercoiling density, we show that the energy barrier is in the $k_{\\rm B} T$\nrange under physiological conditions, thus demonstrating that the limiting step\nto loci encounter is more likely the preceding plectoneme slithering bringing\nthe two loci side by side."
    },
    {
        "anchor": "Trapping and Wiggling: Elastohydrodynamics of Driven Microfilaments: We present a general theoretical analysis of semiflexible filaments subject\nto viscous drag or point forcing. These are the relevant forces in dynamic\nexperiments designed to measure biopolymer bending moduli. By analogy with the\n``Stokes problems\" in hydrodynamics (fluid motion induced by that of a wall\nbounding a viscous fluid), we consider the motion of a polymer one end of which\nis moved in an impulsive or oscillatory way. Analytical solutions for the\ntime-dependent shapes of such moving polymers are obtained within an analysis\napplicable to small-amplitude deformations. In the case of oscillatory driving,\nparticular attention is paid to a characteristic length determined by the\nfrequency of oscillation, the polymer persistence length, and the viscous drag\ncoefficient. Experiments on actin filaments manipulated with optical traps\nconfirm the scaling law predicted by the analysis and provide a new technique\nfor measuring the elastic bending modulus. A re-analysis of several published\nexperiments on microtubules is also presented.",
        "positive": "Competing interactions in two dimensional Coulomb systems: Surface\n  charge heterogeneities in co-assembled cationic-anionic incompatible mixtures: A binary mixture of oppositely charged components confined to a plane such as\ncationic and anionic lipid bilayers may exhibit local segregation. The relative\nstrength of the net short range interactions, which favors macroscopic\nsegregation, and the long range electrostatic interactions, which favors\nmixing, determines the length scale of the finite size or microphase\nsegregation. The free energy of the system can be examined analytically in two\nseparate regimes, when considering small density fluctuations at high\ntemperatures, and when considering the periodic ordering of the system at low\ntemperatures (F. J. Solis and M. Olvera de la Cruz, J. Chem. Phys. 122, 054905\n(2000)). A simple Molecular Dynamics simulation of oppositely charged monomers,\ninteracting with a short range Lennard Jones potential and confined to a two\ndimensional plane, is examined at different strengths of short and long range\ninteractions. The system exhibits well-defined domains that can be\ncharacterized by their periodic length-scale as well as the orientational\nordering of their interfaces. By adding salt, the ordering of the domains\ndisappears and the mixture macroscopically phase segregates in agreement with\nanalytical predictions."
    },
    {
        "anchor": "A simple monatomic ideal glass former: the glass transition by a\n  first-order phase transition above the melting point: A liquid can form under cooling a glassy state either as a result of a\ncontinuous slowing down or by a first order polyamorphous phase transition. The\nsecond scenario has so far always been observed below the melting point where\nit interfered with crystalline nucleation. We report the first observation of\nthe liquid-glass transition by a first order phase transition above the melting\npoint. The observation was made in a molecular dynamics simulation of a\none-component system with a model metallic pair potential. This is also the\nfirst observation of a simple monatomic ideal glass former -- a liquid that\navoids crystallization at any cooling rate. Besides its conceptual importance,\nthis result indicates a possibility of existence of metallic ideal glass\nformers.",
        "positive": "From Flow to Jamming: Lattice Gas Automaton Simulations in Granular\n  Materials: We introduce the first extension of a Lattice Gas Automaton (LGA) model to\naccurately replicate observed emergent phenomena in granular materials with a\nspecial focus on previously unexplored jamming transitions by incorporating\ngravitational effects, energy dissipation in particle collisions, and wall\nfriction. We successfully reproduce flow rate evolution, density wave\nformation, and jamming transition observed in experiments. We also explore the\ncritical density at which jamming becomes probable. This research advances our\nunderstanding of granular dynamics and offers insights into the jamming\nbehavior of granular materials."
    },
    {
        "anchor": "Mixing-demixing transition and void formation in quasi-2D binary\n  mixtures on a sphere: Motivated by observations of heterogeneous domain structure on the surface of\ncells and vesicles and by domain formation due to the adsorption of complex\nmolecules onto composite membranes, we consider a minimal quasi 2D-model to\ndescribe the structure of binary mixtures on the surface of a spherical\nparticle. We study the effect of miscibility and adsorbing particle (AP)\naddition on the mixture structure. We define a new scalar quantity, the\ngeodesic mixing parameter $\\Xi$, through which we detail the effect of\nmiscibility and the role of preferential affinity of APs with one of the two\ncomponents of the mixture, distinguishing unambiguously between mixing and\ndemixing solely induced by APs. Finally, by inspecting the distributions of\nvoid sizes, we show how void formation is ruled by miscibility and AP-mixture\ninteractions, which control the transition from exponentially-tailed to\nfat-tailed distributions.",
        "positive": "Propagation and Relaxation of Tension in Stiff Polymers: We present a unified theory for the longitudinal dynamic response of a stiff\npolymer in solution to various external perturbations (mechanical excitations,\nhydrodynamic flows, electrical fields, temperature quenches ...) that can be\nrepresented as sudden changes of ambient/boundary conditions. The theory relies\non a comprehensive analysis of the non--equilibrium propagation and relaxation\nof backbone stresses in a wormlike chain. We recover and substantially extend\nprevious results based on heuristic arguments. Intriguing new experimental\nimplications are pointed out."
    },
    {
        "anchor": "Hydrogen-bond equilibria and life times in a supercooled monohydroxy\n  alcohol: Dielectric loss spectra covering 13 decades in frequency were collected for\n2-ethyl-1-hexanol, a monohydroxy alcohol that exhibits a prominent Debye-like\nrelaxation, typical for several classes of hydrogen-bonded liquids. The thermal\nvariation of the dielectric absorption amplitude agrees well with that of the\nhydrogen-bond equilibrium population, experimentally mapped out using near\ninfrared (NIR) and nuclear magnetic resonance (NMR) measurements. Despite this\nagreement, temperature-jump NIR spectroscopy reveals that the hydrogen-bond\nswitching rate does not define the frequency position of the prominent\nabsorption peak. This contrasts with widespread notions and models based\nthereon, but is consistent with a recent approach.",
        "positive": "Discrete rearranging disordered patterns: Prediction of elastic and\n  plastic behaviour, and application to two-dimensional foams: We study the elasto-plastic behaviour of materials made of individual\n(discrete) objects, such as a liquid foam made of bubbles. The evolution of\npositions and mutual arrangements of individual objects is taken into account\nthrough statistical quantities, such as the elastic strain of the structure,\nthe yield strain and the yield function. The past history of the sample plays\nno explicit role, except through its effect on these statistical quantities.\nThey suffice to relate the discrete scale with the collective, global scale. At\nthis global scale, the material behaves as a continuous medium; it is described\nwith tensors such as elastic strain, stress and velocity gradient. We write the\ndifferential equations which predict their elastic and plastic behaviour in\nboth the general case and the case of simple shear. An overshoot in the shear\nstrain or shear stress is interpreted as a rotation of the deformed structure,\nwhich is a purely tensorial effect that exists only if the yield strain is at\nleast of order 0.3. We suggest practical applications, including: when to\nchoose a scalar formalism rather than a tensorial one; how to relax trapped\nstresses; and how to model materials with a low, or a high, yield strain."
    },
    {
        "anchor": "Isomorph invariance of Couette shear flows simulated by the SLLOD\n  equations of motion: Non-equilibrium molecular dynamics simulations were performed to study the\nthermodynamic, structural, and dynamical properties of the single-component\nLennard-Jones and the Kob-Andersen binary Lennard-Jones liquids. Both systems\nare known to be strongly correlating, i.e., have strong correlations between\nequilibrium thermal fluctuations of virial and potential energy. Such systems\nhave good isomorphs, i.e., curves in the thermodynamic phase diagram along\nwhich structural, dynamical, and some thermodynamic quantities are invariant\nwhen expressed in reduced units. The SLLOD equations of motion were used to\nsimulate Couette shear flows of the two systems. We show analytically that\nthese equations are isomorph invariant provided the reduced strain rate is\nfixed along the isomorph. Since isomorph invariance is generally only\napproximate, a range of shear rates were simulated to test for the predicted\ninvariance, covering both the linear and non-linear regimes. For both systems,\nwhen represented in reduced units the radial distribution function and the\nintermediate scattering function collapse for state points that are isomorphic.\nThe strain-rate dependence of the viscosity, which exhibits shear thinning, is\nalso invariant along an isomorph. Our results extend the isomorph concept to\nthe state-state non-equilibrium situation of a shear flow, in which the phase\ndiagram is three dimensional because the shear rate defines the third\ndimension.",
        "positive": "Scaling and hydrodynamic effects in lamellar ordering: We study the kinetics of domain growth of fluid mixtures quenched from a\ndisordered to a lamellar phase. At low viscosities, in two dimensions, when\nhydrodynamic modes become important, dynamical scaling is verified in the form\n  $C(\\vec k, t) \\sim L^{\\alpha} f[(k-k_M)L]$ where $C$ is the structure factor\nwith maximum at $k_M$ and\n  $L$ is a typical length changing from power law to logarithmic growth at late\ntimes. The presence of extended defects can explain the behavior of $L$.\nThree-dimensional simulations confirm that diffuse grain boundaries inhibit\ncomplete ordering of lamellae. Applied shear flow alleviates frustration and\ngives power-law growth at all times."
    },
    {
        "anchor": "Experimental evidence of enhanced transport in supernematics: Deviations of molecular shapes from spherical symmetry may give rise to a\nvariety of novel phenomena, including their dynamic behavior. It has recently\nbeen predicted [Mazza \\textit{et al}. Phys. Rev. Lett. \\textbf{105}, 227802\n(2010)] that liquid crystals in the reentrant nematic phases may show\nunexpectedly high rates of translational displacements. Using broadband\ndielectric spectroscopy and a single-component thermotropic liquid crystal we\nexplore molecular dynamics in the vicinity of the reentrant nematic transition\nand find the formation of a maximum in the mobilities upon changing\ntemperature. The occurrence of the high mobility states are found to be\nhistory-dependent due to the formation of metastable mesophases on heating. The\nexperimental results are further supported by computer simulation. Our results\ncontribute to the clarification of an ongoing controversy on the dynamics of\nreentrant nematics.",
        "positive": "Elasticity and Response in Nearly Isostatic Periodic Lattices: The square and kagome lattices with nearest neighbor springs of spring\nconstant $k$ are isostatic with a number of zero-frequency modes that scale\nwith their perimeter. We analytically study the approach to this isostatic\nlimit as the spring constant $k'$ for next-nearest-neighbor bonds vanishes. We\nidentify a characteristic frequency $\\omega^* \\sim \\sqrt{k'}$ and length $l^*\n\\sim \\sqrt{k/k'}$ for both lattices. The shear modulus $C_{44}= k'$ of the\nsquare lattice vanishes with $k'$, but that for the kagome lattice does not."
    },
    {
        "anchor": "Morphological transitions of active Brownian particle aggregates on\n  porous walls: Motility-induced wall aggregation of active Brownian particles (ABPs) is a\nwell-studied phenomenon. Here, we study the aggregation of ABPs on porous\nwalls, which allows the particles to penetrate through at large motility. We\nshow that the active aggregates undergo a morphological transition from a\nconnected dense-phase to disconnected droplets with an increase in wall\nporosity and the particle self-motility, similar to wetting-dewetting\ntransitions in equilibrium fluids. We show that both morphologically distinct\nstates are stable, and independent of initial conditions at least in some\nparameter regions. Our analysis reveals that changes in wall porosity affect\nthe intrinsic properties of the aggregates and changes the effective\nwall-aggregate interfacial tension, consistent with the appearance of the\nmorphological transition. Accordingly, a close analysis of the density, as well\nas orientational distribution, indicates that the underlying reason for such\nmorphological transitions is not necessarily specific to the systems with\nporous walls, and it can be possible to observe in a larger class of confined,\nactive systems by tuning the properties of confining walls.",
        "positive": "Fractal packing of nanomaterials: Cohesive particles form agglomerates that are usually very porous. Their\ngeometry, particularly their fractal dimension, depends on the agglomeration\nprocess (diffusion-limited or ballistic growth by adding single particles or\ncluster-cluster aggregation). However, in practice, the packing structure\ndepends not only on the initial formation but also on the mechanical processing\nof the agglomerate after it has grown. Surprisingly, the packing converges to a\nstatistically invariant structure under certain process conditions, independent\nof the initial growth process. We consider the repeated fragmentation on a\ngiven length scale, followed by ballistic agglomeration. Examples of\nfragmentation are sieving with a given mesh size or dispersion in a turbulent\nfluid. We model the agglomeration by gravitational sedimentation. The\nasymptotic structure is fractal up to the fragmentation length scale, and the\nfragments have a power-law size distribution. A scaling relation connects the\npower law and the fractal dimension."
    },
    {
        "anchor": "Ultrasonic study and molecular simulation of propylene glycol at\n  pressure up to 1.4 GPa: We report an ulsrasonic measurements of density and bulk modulus of propylene\nglycol at room temperature and at the temperature of liquid nitrogen combined\nwith molecular dynamics simulations with two different force fields. We find\nthat experimental density of propylene glycol at room temperature is well\ndescribed within COMPASS force fields simulations, while the bulk modulus from\nsimulation deviates from the experimental one. Number of hydrogen bonds in\npropylene glycol is also evaluated.",
        "positive": "Dipolar Rings of Microscopic Ellipsoids: Magnetic Manipulation and Cell\n  Entrapment: We study the formation and dynamics of dipolar rings composed by microscopic\nferromagnetic ellipsoids, which self-assemble in water by switching the\ndirection of the applied field. We show how to manipulate these fragile\nstructures and control their shape via application of external static and\noscillating magnetic fields. We introduce a theoretical framework which\ndescribes the ring deformation under an applied field, allowing to understand\nthe underlying physical mechanism. Our microscopic rings are finally used to\ncapture, entrap and later release a biological cell via magnetic command, i.e.\nperforming a simple operation which can be implemented in other microfluidic\ndevices which make use of ferromagnetic particles."
    },
    {
        "anchor": "Looping dynamics of flexible chain with internal friction at different\n  degree of compactness: Recently single molecule experiments have shown the importance of internal\nfriction in biopolymer dynamics. Such studies also suggested that the internal\nfriction although independent of solvent viscosity has strong dependence on\ndenaturant concentration. Recent simulations also support such propositions by\npointing out weak interactions to be the origin of internal friction in\nproteins. Here we made an attempt to investigate how a single polymer chain\nwith internal friction undergoes reconfiguration and looping dynamics in a\nconfining potential which accounts for the presence of the denaturant, by using\nrecently proposed Compacted Rouse with internal friction (CRIF). We also\nincorporated the effect of hydrodynamics by extending this further to Compacted\nZimm with internal friction (CZIF). All the calculations are carried out within\nthe Wilemski Fixmann (WF) framework. By changing the strength of the\nconfinement we mimicked chains with different degrees of compactness at\ndifferent denaturant concentrations. While compared with experiments our\nresults are found to be in good agreement.",
        "positive": "Projectile interactions in granular impact cratering: We present evidence for the interactions between a ball and the container\nboundaries, as well as between two balls, that are mediated by the granular\nmedium during impact cratering. The presence of the bottom boundary affects the\nfinal penetration depth only for low drop heights with shallow filling, in\nwhich case, surprisingly, the penetration becomes deeper. By contrast the\npresence of the side wall causes less penetration and also an effective\nrepulsion. Repulsion is also found for two balls dropped side-by-side."
    },
    {
        "anchor": "Monte Carlo simulation of growth of hard-sphere crystals on a square\n  pattern: Monte Carlo simulations of the colloidal epitaxy of hard spheres (HSs) on a\nsquare pattern have been performed. This is an extension of previous\nsimulations; we observed a shrinking intrinsic stacking fault running in an\noblique direction through the glide of a Shockley partial dislocation\nterminating its lower end in fcc (001) stacking [Mori et al., Molec. Phys. 105\n(2007) 1377], which was an answer to a question why the defect in colloidal\ncrystals reduced by gravity [Zhu et al., Nature 387 (1997) 883]. We have\nresolved one of shortcomings of the previous simulations; the driving force for\nfcc (001) stacking, which was stress from a small periodic boundary simulation\nbox, has been replaced with the stress from a pattern on the bottom. We have\nobserved disappearance of stacking fault in this realizable condition. Sinking\nof the center of gravity has been smooth and of a single relaxation mode under\nthe condition that the gravitational energy mgd is slightly less than the\nthermal energy kT. In the snapshots tetrahedral structures have appeared often,\nsuggesting formation of staking fault tetrahedra.",
        "positive": "Polymers in long-range-correlated disorder: We study the scaling properties of polymers in a d-dimensional medium with\nquenched defects that have power law correlations ~r^{-a} for large separations\nr. This type of disorder is known to be relevant for magnetic phase\ntransitions. We find strong evidence that this is true also for the polymer\ncase. Applying the field-theoretical renormalization group approach we perform\ncalculations both in a double expansion in epsilon=4-d and delta=4-a up to the\n1-loop order and secondly in a fixed dimension (d=3) approach up to the 2-loop\napproximation for different fixed values of the correlation parameter, 2=<a=<3.\nIn the latter case the numerical results need appropriate resummation. We find\nthat the asymptotic behavior of self-avoiding walks in three dimensions and\nlong-range-correlated disorder is governed by a set of separate exponents. In\nparticular, we give estimates for the 'nu' and 'gamma' exponents as well as for\nthe correction-to-scaling exponent 'omega'. The latter exponent is also\ncalculated for the general m-vector model with m=1,2,3."
    },
    {
        "anchor": "Granular convergence as an iterated local map: Granular convergence is a property of a granular pack as it is repeatedly\nsheared in a cyclic, quasistatic fashion, as the packing configuration changes\nvia discrete events. Under suitable conditions the set of microscopic\nconfigurations encountered converges to a periodic sequence after sufficient\nshear cycles. Prior work modeled this evolution as the iteration of a\npre-determined, random map from a set of discrete configurations into itself.\nIterating such a map from a random starting point leads to similar periodic\nrepetition. This work explores the effect of restricting the randomness of such\nmaps in order to account for the local nature of the discrete events. The\nnumber of cycles needed for convergence shows similar statistical behavior to\nthat of numerical granular experiments. The number of cycles in a repeating\nperiod behaves only qualitatively like these granular studies.",
        "positive": "Wet to dry self-transitions in dense emulsions: from order to disorder\n  and back: One of the most distinctive hallmarks of many-body systems far from\nequilibrium is the spontaneous emergence of order under conditions where\ndisorder would be plausibly expected. Here, we report on the self-transition\nbetween ordered and disordered emulsions in divergent microfluidic channels,\ni.e. from monodisperse assemblies to heterogeneous polydisperse foam-like\nstructures, and back again to ordered ones. The transition is driven by the\nnonlinear competition between viscous dissipation and surface tension forces as\ncontrolled by the device geometry, particularly the aperture angle of the\ndivergent microfluidic channel. An unexpected route back to order is observed\nin the regime of large opening angles, where a trend towards increasing\ndisorder would be intuitively expected."
    },
    {
        "anchor": "Space-Time Correlations in the Orientational Order Parameter and the\n  Orientational Entropy of Water: We introduce the spatial correlation function $C_Q(r)$ and temporal\nautocorrelation function $C_Q(t)$ of the local tetrahedral order parameter\n$Q\\equiv Q(r,t)$. Using computer simulations of the TIP5P model of water, we\ninvestigate $C_Q(r)$ in a broad region of the phase diagram. First we show that\n$C_Q(r)$ displays anticorrelation at $r\\approx 0.32$nm at high temperatures\n$T>T_W\\approx 250$ K, which changes to positive correlation below the Widom\nline $T_W$. Further we find that at low temperatures $C_Q(t)$ exhibits a\ntwo-step temporal decay similar to the self intermediate scattering function,\nand that the corresponding correlation time $\\tau_Q$ displays a dynamic\ncrossover from non-Arrhenius behavior for $T>T_W$ to Arrhenius behavior for\n$T<T_W$. Finally, we define an orientational entropy $S_Q$ associated with the\n{\\it local} orientational order of water molecules, and show that $\\tau_Q$ can\nbe extracted from $S_Q$ using an analog of the Adam-Gibbs relation.",
        "positive": "Close packing density and fracture strength of adsorbed polydisperse\n  particle layers: The close packing density of log-normal and bimodal distributed,\nsurface-adsorbed particles or discs in 2D is studied by numerical simulation.\nFor small spread in particle size, the system orders in a polycrystalline\nstructure of hexagonal domains. The domain size and the packing density both\ndecrease as the spread in particle size is increased up to 10.5+/-0.5%. From\nthis point onwards the system becomes amorphous, and the close packing density\nincreases again with spread in particle size. We argue that the polycrystalline\nand amorphous regions are separated by a Kosterlitz-Thouless-type phase\ntransition. In the amorphous region we find the close packing density to vary\nproportional to the logarithm of the friction factor, or cooling rate. We also\nstudied the fracture behaviour of surface layers of sintered particles.\nFracture strength increases with spread in particle size, but the brittleness\nof the layers shows a minimum at the polycrystalline-amorphous transition. We\nfurther show that mixing distributions of big and small particles generally\nleads to weaker and more brittle layers, even though the close packing density\nis higher than for either of the particle types. We point out applications to\nfoam stability by the Pickering mechanism."
    },
    {
        "anchor": "Structural Analysis of DNA molecule in a confined shell: Recent advances in operating and manipulating DNA have provided unique\nexperimental possibilities in many fields of DNA research, especially in gene\ntherapy. Researchers have deployed many techniques, experimental and\ntheoretical, to study the DNA structure changes due to external perturbation.\nIt is crucial to understand the structural and dynamical changes in the DNA\nmolecules in a confined state to understand and control the self-assembly of\nDNA confined in a chamber or nano-channel for various applications. In the\ncurrent manuscript, we extend the work study the effect of confinement on the\nthermal stability and the structural properties of duplex DNA. The present work\nis an extension of our previous research works. For our study we have\nconsidered a 1 BNA chain that is confined in a cylindrical geometry. How the\ngeometry of the confinement affects the opening and other structural parameters\nof DNA molecule is the objective of this manuscript. We have used a statistical\nmodel(PBD model) and Molecular dynamics simulations for our purpose.",
        "positive": "Dechiralisation lines induced unwinding in confined SmC* liquid crystals: Equilibrium and dynamic behaviors of dechiralisation lines occurring below\nSmC* cell boundaries in planar geometry consitute a polemic topic for several\ndecades. We report new observations in the SmC* phase of the strongly polarized\nliquid crystal CFL08. They are compared with vortex motions in superfluids and\ntype-II superconductors, and we propose a simple heuristic model attempting to\nexplain the intriguing mismatch between bulk helix pitch and inter-lines\ndistance. It results from opposite effects of the helix pitch and surface lines\ncharge value on the equilibrium lines distance. The model assumes that the\nlines electric interactions dominate the cell equilibrium state. In particular\nthe unwinding transition of the bulk helix is provoked by field-induced\ndisplacements of the lines lattices. It permits to relate the lines density and\ncritical fields to intrinsic energy parameters, and to explain the\npitch-distance mismatch, together with its almost constant value across the\ntransition. We foresee the helix pitch and unwinding field variations vs.\nsample width."
    },
    {
        "anchor": "Spinning up and down a Boltzmann gas: Using the average method, we derive a close set of linear equations that\ndescribes the spinning up of an harmonically trapped gas by a rotating\nanisotropy. We find explicit expressions for the needed to transfer angular\nmomentum as well as the decay time induced by a static residual anisotropy.\nThese different time scales are compared with the measured nucleation time and\nlifetime of vortices by the ENS group. We find a good agreement that may\nemphasize the role played by the non-condensed component in thoses experiments.",
        "positive": "Extensile to contractile transition in active microtubule-actin\n  composites generates layered asters with programmable lifetimes: We study a reconstituted composite system consisting of an active microtubule\nnetwork interdigitated with a passive network of entangled F-actin filaments.\nIncreasing viscoelasticity of the F-actin network controls the emergent\ndynamics, inducing a transition from turbulent-like flows to bulk contractions.\nAt intermediate F-actin concentrations, where the active stresses change their\nsymmetry from anisotropic extensile to isotropic contracting, the composite\nseparates into layered asters that coexist with the background turbulent fluid.\nContracted onion-like asters have a radially extending microtubule-rich cortex\nthat envelops alternating layers of microtubules and F-actin. The\nself-regulating layered organization survives aster merging events, which are\nreminiscent of droplet coalescence, and suggest the presence of effective\nsurface tension. Finally, the layered asters are metastable structures. Their\nlifetime, which ranges from minutes to hours, is encoded in the material\nproperties of the composite. Taken together, these results challenge the\ncurrent models of active matter. They demonstrate that the self-organized\ndynamical states and patterns, which are evocative of those observed in the\ncytoskeleton, do not require precise biochemical regulation but can arise due\nto purely mechanical interactions of actively driven filamentous materials."
    },
    {
        "anchor": "Structural anomalies of fluids: Origins in second and higher\n  coordination shells: Compressing or cooling a fluid typically enhances its static interparticle\ncorrelations. However, there are notable exceptions. Isothermal compression can\nreduce the translational order of fluids that exhibit anomalous waterlike\ntrends in their thermodynamic and transport properties, while isochoric cooling\n(or strengthening of attractive interactions) can have a similar effect on\nfluids of particles with short-range attractions. Recent simulation studies by\nYan et al. [Phys. Rev. E 76, 051201 (2007)] on the former type of system and\nKrekelberg et al. [J. Chem. Phys. 127, 044502 (2007)] on the latter provide\nexamples where such structural anomalies can be related to specific changes in\nsecond and more distant coordination shells of the radial distribution\nfunction. Here, we confirm the generality of this microscopic picture through\nanalysis, via molecular simulation and integral equation theory, of\ncoordination shell contributions to the two-body excess entropy for several\nrelated model fluids which incorporate different levels of molecular\nresolution. The results suggest that integral equation theory can be an\neffective and computationally inexpensive first-pass tool for assessing, based\non the pair potential alone, whether new model systems are good candidates for\nexhibiting structural (and hence thermodynamic and transport) anomalies.",
        "positive": "Self-Assembly of Colloidal Superstructures in Coherently Fluctuating\n  Fields: From microscopic fluid clusters to macroscopic droplets, the structure of\nfluids is governed by the Van der Waals force, a force that acts between\npolarizable objects. In this Letter, we derive a general theory that describes\nthe non-equilibrium counterpart to the Van der Waals force, which emerges in\nspatially coherently fluctuating electromagnetic fields. We describe the\nformation of a novel and complex hierarchy of self-organized morphologies in\nmagnetic and dielectric colloid systems. Most striking among these morphologies\nare dipolar foams - colloidal superstructures that swell against gravity and\ndisplay a high sensitivity to the applied field. We discuss the dominance of\nmany body forces and derive the equation of state for a material formed by the\ncoherent Van der Waals force. Our theory is applied to recent experiments in\nparamagnetic colloidal systems and a new experiment is suggested to test the\ntheory."
    },
    {
        "anchor": "Collapse Dynamics of a Homopolymer: Theory and Simulation: We present a scaling theory describing the collapse of a homopolymer chain in\npoor solvent. At time t after the beginning of the collapse, the original\nGaussian chain of length N is streamlined to form N/g segments of length R(t),\neach containing g ~ t monomers. These segments are statistical quantities\nrepresenting cylinders of length R ~ t^{1/2} and diameter d ~ t^{1/4}, but\nstructured out of stretched arrays of spherical globules. This prescription\nincorporates the capillary instability. We compare the time-dependent structure\nfactor derived for our theory with that obtained from ultra-large-scale\nmolecular dynamics simulation with explicit solvent. This is the first time\nsuch a detailed comparison of theoretical and simulation predictions of\ncollapsing chain structure has been attempted. The favorable agreement between\nthe theoretical and computed structure factors supports the picture of the\ncoarse-graining process during polymer collapse.",
        "positive": "Destroying superfluidity by rotating a Fermi gas at unitarity: We study the effect of the rotation on a harmonically trapped Fermi gas at\nzero temperature under the assumption that vortices are not formed. We show\nthat at unitarity the rotation produces a phase separation between a non\nrotating superfluid (S) core and a rigidly rotating normal (N) gas. The\ninterface between the two phases is characterized by a density discontinuity\n$n_{\\rm N}/n_{\\rm S}= 0.85$, independent of the angular velocity. The depletion\nof the superfluid and the angular momentum of the rotating configuration are\ncalculated as a function of the angular velocity. The conditions of stability\nare also discussed and the critical angular velocity for the onset of a\nspontaneous quadrupole deformation of the interface is evaluated."
    },
    {
        "anchor": "Scaling properties of liquid dynamics predicted from a single\n  configuration: Small rigid molecules: Isomorphs are curves in the thermodynamic phase diagram along which structure\nand dynamics are invariant to a good approximation. There are two main ways to\ntrace out isomorphs, the configurational-adiabat method and the\ndirect-isomorph-check method. Recently a new method based on the scaling\nproperties of forces was introduced and shown to work very well for atomic\nsystems [T. B. Schroder, Phys. Rev. Lett. 129, 245501 (2022)]. A unique feature\nof this method is that it only requires a single equilibrium configuration for\ntracing out an isomorph. We here test generalizations of this method to\nmolecular systems and compare to simulations of three simple molecular models:\nthe asymmetric dumbbell model of two Lennard-Jones spheres, the symmetric\ninverse-power-law dumbbell model, and the Lewis-Wahnstr\\\"om o-terphenyl model.\nWe introduce and test two force-based and one torque-based methods, all of\nwhich require just a single configuration for tracing out an isomorph. Overall,\nthe method based on requiring invariant center-of-mass reduced forces works\nbest.",
        "positive": "Following in the footsteps of E. coli: sperm in microfluidic\n  \"strictures\": We briefly describe the similarities of the experiments of sperm motion in\nmicrofluidic \"strictures\" by Zafeeani et al. in 2019 (Sci. Adv. 5, eaav21111,\n2019) and those by Altshuler et al. in 2013 (Soft Matter 9, 1864, 2013). We\nshortly discuss the hydrodynamic elements justifying the strong resemblance\nbetween the two types of experiments, and suggest that other previous results\nin E. coli motion (Soft Matter 11, 6248, 2015) may shed further light on the\nunderstanding of sperm migration."
    },
    {
        "anchor": "Structure, compressibility factor and dynamics of highly size-asymmetric\n  binary hard-disk liquids: By using event-driven molecular dynamics simulation, we investigate effects\nof varying the area fraction of the smaller component on structure,\ncompressibility factor and dynamics of the highly size-asymmetric binary\nhard-disk liquids. We find that the static pair correlations of the large disks\nare only weakly perturbed by adding small disks. The higher-order static\ncorrelations of the large disks, by contrast, can be strongly affected. The\ncompressibility factor of the system first decreases and then increases upon\nincreasing the area fraction of the small disks and separating different\ncontributions to it allows to rationalize this non-monotonic phenomenon.\nFurthermore, adding small disks can influence dynamics of the system in\nquantitative and qualitative ways. For the large disks, the structural\nrelaxation time increases monotonically with increasing the area fraction of\nthe small disks at low and moderate area fractions of the large disks. In\nparticular, \"reentrant\" behavior appears at sufficiently high area fractions of\nthe large disks, strongly resembling the reentrant glass transition in\nshort-ranged attractive colloids and the inverted glass transition in binary\nhard spheres with large size disparity. By tuning the area fraction of the\nsmall disks, relaxation process for the small disks shows concave-to-convex\ncrossover and logarithmic decay behavior, as found in other binary mixtures\nwith large size disparity. Moreover, diffusion of both species is suppressed by\nadding small disks. Long-time diffusion for the small disks shows\npower-law-like behavior at sufficiently high area fractions of the small disks,\nwhich implies precursors of a glass transition for the large disks and a\nlocalization transition for the small disks. Therefore, our results demonstrate\nthe generic dynamic features in highly size-asymmetric binary mixtures.",
        "positive": "Inherent Structures and Kauzmann Temperature of Confined Liquids: Calculations of the thermodynamical properties of a supercooled liquid\nconfined in a matrix are performed with an inherent structure analysis. The\nliquid entropy is computed by means of a thermodynamical integration procedure.\nThe contributions to the free energy of the liquid can be decoupled also in\nconfinement in the configurational and the vibrational part. We show that the\nvibrational entropy can be calculated in the harmonic approximation as in the\nbulk case. The Kauzmann temperature of the confined system is estimated from\nthe behavior of the configurational entropy."
    },
    {
        "anchor": "Polymer plats and multicomponent anyon gases: Anyon systems are studied in connection with several interesting applications\nincluding high $T_C$ superconductivity and topological quantum computing. In\nthis work we show that these systems can be realized starting from directed\npolymers braided together to form a nontrivial link configuration belonging to\nthe topological class of plats. The statistical sum of a such plat is related\nhere to the partition function of a two-component anyon gas. The constraints\nthat preserve the topological configuration of the plat are imposed on the\npolymer trajectories using the so-called Gauss linking number, a topological\ninvariant that has already been well studied in polymer physics. Due to these\nconstraints, short-range forces act on the monomers or, equivalently, on the\nanyon quasiparticles in a way that closely resembles the appearance of reaction\nforces in the constrained systems of classical mechanics. If the polymers are\nhomogeneous, the anyon system reaches a self-dual point, in which these forces\nvanish exactly. A class of self-dual solutions that minimize the energy of the\nanyons is derived. The two anyon gas discussed here obeys an abelian\nstatistics, while for quantum computing it is known that nonabelian anyons are\nnecessary. However, this is a limitation due to the use of the Gauss linking\ninvariant to impose the topological constraints, which is a poor topological\ninvariant and is thus unable to capture the nonabelian characteristics of the\nbraided polymer chains. A more refined treatment of the topological constraints\nwould require more sophisticated topological invariants, but so far their\napplication to the statistical mechanics of linked polymers is an open problem.",
        "positive": "Thermodynamic cycles with active matter: Active matter constantly dissipates energy to power the self-propulsion of\nits microscopic constituents. This opens the door to designing innovative\ncyclic engines without any equilibrium equivalent. We offer a consistent\nthermodynamic framework to characterize and optimize the performances of such\ncycles. Based on a minimal model, we put forward a protocol which extracts work\nby controlling only the properties of the confining walls at boundaries, and we\nrationalize the transitions between optimal cycles. We show that the\ncorresponding power and efficiency are generally proportional, so that they\nreach their maximum values at same cycle time in contrast with thermal cycles,\nand we provide a generic relation constraining the fluctuations of the power."
    },
    {
        "anchor": "Stimulated binding of polymer chains by narrow tube confinement: In biology, there are several processes in which unfolded protein chains are\ntransported along narrow-tube channels. Normally, without such a severe\nconfigurational constraint, unfolded polypeptides would not bind to each other.\nHowever, when chain entropy is much reduced in the narrow channel, we find that\npolypeptide chains have a propensity to bind, even if there is no great\npotential energy gain in doing so. We find the average length of binding m*\n(the number of monomers at the chain ends that form bonds) and the critical\ntube diameter at which such constrained binding occurs. We carry out Brownian\ndynamics simulations of tightly confined chains, demonstrating their binding\nover the characteristic length m*, changing in tubes of different diameter.",
        "positive": "Direct Computation of Two-Phase Icosahedral Equilibria of Lipid Bilayer\n  Vesicles: Correctly formulated continuum models for lipid-bilayer membranes present a\nsignificant challenge to computational mechanics. In particular, the\nmid-surface behavior is that of a 2-dimensional fluid, while the membrane\nresists bending much like an elastic shell. Here we consider a well-known\nHelfrich-Cahn-Hilliard model for two-phase lipid-bilayer vesicles,\nincorporating mid-surface fluidity, curvature elasticity and a phase field. We\npresent a systematic approach to the direct computation of vesical\nconfigurations possessing icosahedral symmetry, which have been observed in\nexperiment and whose mathematical existence has recently been established. We\nfirst introduce a radial-graph formulation to overcome the difficulties\nassociated with fluidity within a conventional Lagrangian description. We use\nthe so-called subdivision surface finite element method combined with an\nicosahedral-symmetric mesh. The resulting discrete equations are\nwell-conditioned and inherit equivariance properties under a representation of\nthe icosahedral group. We use group-theoretic methods to obtain a reduced\nproblem that captures all icosahedral-symmetric solutions of the full problem.\nFinally we explore the behavior of our reduced model, varying numerous physical\nparameters present in the mathematical model."
    },
    {
        "anchor": "Two Coupled Mechanisms Produce Fickian, yet non-Gaussian Diffusion in\n  Heterogeneous Media: Fickian yet non-Gaussian diffusion is observed in several biological and soft\nmatter systems, yet the underlying mechanisms behind the emergence of\nnon-Gaussianity while retaining a linear mean square displacement remain\nspeculative. Here, we characterize quantitatively the effect of spatial\nheterogeneities on the appearance of non-Gaussianity in Fickian diffusion. We\nstudy the diffusion of fluorescent colloidal particles in a matrix of\nmicropillars having a range of structural configurations: from completely\nordered to completely random. We show that non-Gaussianity emerges as a direct\nconsequence of two coupled factors; individual particle diffusivities become\nspatially dependent in a heterogeneous randomly structured environment, and the\nspatial distribution of the particles varies significantly in such\nenvironments, further influencing the diffusivity of a single particle. The\ncoupled mechanisms lead to a considerable non-Gaussian nature even due to weak\ndisorder in the arrangement of the micropillars. A simple mathematical model\nvalidates our hypothesis that non-Gaussian yet Fickian diffusion in our system\narises from the superstatistical behavior of the ensemble in a structurally\nheterogeneous environment. The two mechanisms identified here are relevant for\nmany systems of crowded heterogeneous environments where non-Gaussian diffusion\nis frequently observed, for example in biological systems, polymers, gels and\nporous materials.",
        "positive": "Elastic disk with isoperimetric Cosserat coating: A circular elastic disk is coated with an elastic beam, absorbing shear and\nnormal forces without deformation and linearly reacting to a bending moment\nwith a change in curvature. The inexstensibility of the elastic beam introduces\nan isoperimetric constraint, so that the length of the initial circumference of\nthe disk is constrained to remain fixed during the loading of the disk/coating\nsystem. The mechanical model for this system is formulated, solved for general\nloading, and particularized to the case of two equal and opposite traction\ndistributions, each applied on a small boundary segment (thus modelling\nindentation of a coated fiber). The stress fields, obtained via complex\npotentials, are shown to evidence a nice correspondence with photoelastic\nexperiments, ad hoc designed and performed. The presented results are useful\nfor the design of coated fibers at the micro and nano scales."
    },
    {
        "anchor": "Study of Structural Evolution During Controlled Degradation of Ultrathin\n  Polymer Films: The structural aspects of polyacrylamide thin films annealed at degradation\nthreshold temperature have been studied as a function of annealing time using\nin situ X-ray reflectivity technique in vacuum. We observe significant decrease\nof thickness and increase of density with annealing time for all the films. The\ndynamical behavior of the changes was modeled in terms of two distinct\nexponential decay functions, following our earlier observation of two different\ntime scales for the chemical modification pathways, and was found to be in\nexcellent agreement with the data. The diffusion coefficients of the polymer\nchains corresponding to the two modes are found to be different by an order of\nmagnitude. It was found that the two dynamical modes correspond to the\nformation of two degradation products at two different rates. The larger time\nconstants for both the modes in case of thickness reduction compare to the\nchemical changes was explained in terms of inter-chain entanglement and\nattachment of the polymer with the substrate.",
        "positive": "Frequency-dependent Hydrodynamic Interaction Between Two Solid Spheres: Hydrodynamic interactions play an important role in many areas of soft matter\nscience. In simulations with implicit solvent, various techniques such as\nBrownian or Stokesian dynamics explicitly include hydrodynamic interactions a\nposteriori by using hydrodynamic diffusion tensors derived from the Stokes\nequation. However, this equation assumes the interaction to be instantaneous\nwhich is an idealized approximation and only valid on long time scales. In the\npresent paper, we go one step further and analyze the time-dependence of\nhydrodynamic interactions in a compressible fluid on the basis of the\nlinearized Navier-Stokes equation. The theoretical results show that the\ncompressibility of the fluid has a significant impact on frequency-dependent\npair interactions.\n  The predictions of the hydrodynamic theory are compared to molecular dynamics\nsimulations of two solid spheres in a Lennard-Jones fluid. For this system we\nreconstruct memory functions by extending the inverse Volterra technique. The\nsimulation data agree very well with the theory, therefore, the theory can be\nused to implement dynamically consistent hydrodynamic interactions in the\nincreasingly popular field of non-Markovian modeling."
    },
    {
        "anchor": "Physically-informed data-driven modeling of active nematics: A continuum description is essential for understanding a variety of\ncollective phenomena in active matter. However, building quantitative continuum\nmodels of active matter from first principles can be extremely challenging due\nto both the gaps in our knowledge and the complicated structure of nonlinear\ninteractions. Here we use a novel physically-informed data-driven approach to\nconstruct a complete mathematical model of an active nematic from experimental\ndata describing kinesin-driven microtubule bundles confined to an oil-water\ninterface. We find that the structure of the model is similar to the\nLeslie-Ericksen and Beris-Edwards models, but there are significant and\nimportant differences. Rather unexpectedly, elastic effects are found to play\nno role in the experiments considered, with the dynamics controlled entirely by\nthe balance between active stresses and friction stresses.",
        "positive": "Short-time transport properties of bidisperse suspensions and porous\n  media: a Stokesian Dynamics study: We present a comprehensive computational study of the short-time transport\nproperties of bidisperse neutral colloidal suspensions and the corresponding\nporous media. Our study covers bidisperse particle size ratios up to $4$, and\ntotal volume fractions up to and beyond the monodisperse hard-sphere close\npacking limit. The many-body hydrodynamic interactions are computed using\nconventional Stokesian Dynamics (SD) via a Monte-Carlo approach. We address\nsuspension properties including the short-time translational and rotational\nself-diffusivities, the instantaneous sedimentation velocity, the\nwavenumber-dependent partial hydrodynamic functions, and the high-frequency\nshear and bulk viscosities; and porous media properties including the\npermeability and the translational and rotational hindered diffusivities. We\ncarefully compare the SD computations with existing theoretical and numerical\nresults. For suspensions, we also explore the range of validity of various\napproximation schemes, notably the Pairwise Additive (PA) approximations with\nthe Percus-Yevick structural input. We critically assess the strengths and\nweaknesses of the SD algorithm for various transport properties. For very dense\nsystems, we discuss in detail the interplay between the hydrodynamic\ninteractions and the structures due to the presence of a second species of a\ndifferent size."
    },
    {
        "anchor": "Membrane buckling and the determination of Gaussian curvature modulus: Biological membranes are able to exhibit various morphology due to the\nfluidity of the lipid molecules within the monolayers. The shape transformation\nof membranes has been well described by the classical Helfrich theory, which\nconsists only a few phenomenological parameters, including the mean and the\nGaussian curvature modulus. Though various methods have been proposed to\nmeasure the mean curvature modulus, determination of the Gaussian curvature\nmodulus remains difficult both in experiments and in simulation. In this paper\nwe study the buckling process of a rectangular membrane and a circular membrane\nsubject to compressive stresses and under different boundary conditions. We\nfind that the buckling of a rectangular membrane takes place continuously,\nwhile the buckling of a circular membrane can be discontinous depending on the\nboundary conditions. Furthermore, our results show that the stress-strain\nrelationship of a buckled circular membrane can be used to effectively\ndetermine the Gaussian curvature modulus.",
        "positive": "Loop formation in polymers in crowded environment: We analyze the probability of a single loop formation in a long flexible\npolymer chain in disordered environment in $d$ dimensions. The structural\ndefects are considered to be correlated on large distances $r$ according to a\npower law $\\sim r^{-a}$. Working within the frames of continuous chain model\nand applying the direct polymer renormalization scheme, we obtain the values of\ncritical exponents governing the scaling of probabilities of loop formation\nwith various positions along the chain as function of loops length. Our results\nquantitatively reveal that the presence of structural defects in environment\ndecreases the probability of loop formation in polymer macromolecules."
    },
    {
        "anchor": "Shaping active matter from crystalline solids to active turbulence: Active matter drives its constituent agents to move autonomously by\nharnessing free energy, leading to diverse emergent states with relevance to\nboth biological processes and inanimate functionalities. Achieving maximum\nreconfigurability of active materials with minimal control remains a desirable\nyet challenging goal. Here, we employ large-scale, agent-resolved simulations\nto demonstrate that modulating the activity of a wet phoretic medium alone can\ngovern its solid-liquid-gas phase transitions and, subsequently,\nlaminar-turbulent transitions in fluid phases, thereby shaping its emergent\npattern. These two progressively emerging transitions, hitherto unreported,\nbring us closer to perceiving the parallels between active matter and\ntraditional matter. Our work reproduces and reconciles seemingly conflicting\nexperimental observations on chemically active systems, presenting a unified\nlandscape of phoretic collective dynamics. These findings enhance the\nunderstanding of long-range, many-body interactions among phoretic agents,\noffer new insights into their non-equilibrium collective behaviors, and provide\npotential guidelines for designing reconfigurable materials.",
        "positive": "Multiscale Simulation of History Dependent Flow in Polymer Melt: We have developed a new multiscale simulation technique to investigate\nhistory-dependent flow behavior of entangled polymer melt, using a smoothed\nparticle hydrodynamics simulation with microscopic simulators that account for\nthe dynamics of entangled polymers acting on each fluid element. The multiscale\nsimulation technique is applied to entangled polymer melt flow around a\ncircular obstacle in a two-dimensional periodic system. It is found that the\nstrain-rate history-dependent stress of the entangled polymer melt affects its\nflow behavior, and the memory in the stress causes nonlinear behavior even in\nthe regions where ${\\rm Wi} \\le 1$. The spatial distribution of the\nentanglements $<Z>$ is also investigated. The slightly low entanglement region\nis observed around the obstacle and is found to be broaden in the downstream\nregion."
    },
    {
        "anchor": "Measuring the bending rigidity of microbial glucolipid (biosurfactant)\n  bioamphiphile self-assembled structures by neutron spin-echo (NSE):\n  interdigitated vesicles, lamellae and fibers: Bending rigidity, k, is classically measured for lipid membranes to\ncharacterize their nanoscale mechanical properties as a function of\ncomposition. Widely employed as a comparative tool, it helps understanding the\nrelationship between the lipid's molecular structure and the elastic properties\nof its corresponding bilayer. Widely measured for phospholipid membranes in the\nshape of giant unilamellar vesicles (GUVs), bending rigidity is determined here\nfor three self-assembled structures formed by a new biobased glucolipid\nbioamphiphile, rather associated to the family of glycolipid biosurfactants\nthan phospholipids. In its oleyl form, glucolipid G-C18:1 can assemble into\nvesicles or crystalline fibers, while in its stearyl form, glucolipid G-C18:0\ncan assemble into lamellar gels. Neutron spin-echo (NSE) is employed in the\nq-range between 0.3 nm-1 (21 nm) and 1.5 nm-1 (4.1 nm) with a spin-echo time in\nthe range of up to 500 ns to characterize the bending rigidity of three\ndifferent structures (Vesicle suspension, Lamellar gel, Fiber gel) solely\ncomposed of a single glucolipid. The low (k= 0.30 $\\pm$ 0.04 kbT) values found\nfor the Vesicle suspension and high values found for the Lamellar (k= 130 $\\pm$\n40 kbT) and Fiber gels (k= 900 $\\pm$ 500 kbT) are unusual when compared to most\nphospholipid membranes. By attempting to quantify for the first time the\nbending rigidity of self-assembled bioamphiphiles, this work not only\ncontributes to the fundamental understanding of these new molecular systems,\nbut it also opens new perspectives in their integration in the field of soft\nmaterials.",
        "positive": "Triggers and signatures of shear banding in steady and time-dependent\n  flows: This precis is aimed as a practical field-guide to situations in which shear\nbanding might be expected in complex fluids subject to an applied shear flow.\nSeparately for several of the most common flow protocols, it summarises the\ncharacteristic signatures in the measured bulk rheological signals that suggest\nthe presence of banding in the underlying flow field. It does so both for a\nsteady applied shear flow, and for the time-dependent protocols of shear\nstartup, step stress, finite strain ramp, and large amplitude oscillatory\nshear. An important message is that banding might arise rather widely in flows\nwith a strong enough time-dependence, even in fluids that do not support\nbanding in a steadily applied shear flow. This suggests caution in comparing\nexperimental data with theoretical calculations that assume a homogeneous shear\nflow. In a brief postlude, we also summarise criteria in similar spirit for the\nonset of necking in extensional filament stretching."
    },
    {
        "anchor": "Experimental study of shear band formation: bifurcation and localization: We report the experimental observation of the bifurcation at the origin of\nlocalization of the deformation in a granular material submitted to uniaxial\ncompression. We present a quantitative characterization of the heterogeneity in\nthe strain field repartition allowing to evidence objectively the existence of\na bifurcation initiating the shear bands formation process. We show that this\nbifurcation is supercritical and has no clear signature on the stress-strain\ncurve. At the bifurcation, a symmetry breaking occurs characterized by the\nemergence of a well-defined orientation corresponding to the Mohr-Coulomb\nangle. Yet, plasticity is still diffuse and the shear band extension is of the\norder of the sample width. While loading proceeds, the shear band narrows until\nit reaches, after the peak of the stress-strain curve, a stationary width.",
        "positive": "Self-Assembly of Nanoparticles from Evaporating Sessile Droplets: Fresh\n  Look into the Role of Particle/Substrate Interaction: We studied the dependence of solid deposit shape obtained by free drying of\nsessile drops on the particles concentration and\nDerjaguin-Landau-Verwey-Overbeek (DLVO) particle/substrate interaction. In\ncontrast to previous contributions using pH as a control parameter of\ninteractions, we investigated an unprecedentedly wide range of concentrations\nand particle/substrate DLVO forces by modifying the nature of the substrate and\nparticles as well as their size and surface chemistry whereas long-distance\nrepulsive interactions between particles were maintained for most of the drying\ntime. Our main result is that the different shapes of deposits obtained by\nmodifying the particle concentration are the same in the different regimes of\nconcentration regardless of particle/substrate interaction in the studied range\nof DLVO forces and particle concentrations. The second result is that, contrary\nto expectations, the dominant morphology of dry patterns at low particle\nconcentration always shows a dot-like pattern for all the studied systems."
    },
    {
        "anchor": "Dynamical behavior of disordered spring networks: We study the dynamical rheology of spring networks with a percolation model\nconstructed by bond dilution in a two-dimensional triangular lattice.\nHydrodynamic interactions are implemented by a Stokesian viscous coupling\nbetween the network nodes and a uniformly deforming liquid. Our simulations\nshow that in a critical connectivity regime, these systems display weak power\nlaw rheology in which the complex shear modulus scales with frequency as G^* ~\n(i * omega)^Delta where Delta = 0.41, in discord with a mean field prediction\nof Delta = 1/2. The weak power law rheology in the critical regime can be\nunderstood from a simple scaling relation between the macroscopic rheology and\nthe nonaffine strain fluctuations, which diverge with vanishing frequency for\nisostatic networks. We expand on a dynamic effective medium theory, showing\nthat it quantitatively describes the rheology of a diluted triangular lattice\nfar from isostaticity; although the EMT correctly predicts the scaling form for\nthe rheology of near-isostatic networks, there remains a quantitative disparity\ndue to the mean-field nature of the EMT. Surprisingly, by connecting this\ncritical scaling of the rheology with that of the strain fluctuations, we find\nthat the dynamical behavior of disordered spring networks is fully determined\nby the critical exponents that govern the behavior of elastic network in the\nabsence of viscous interactions.",
        "positive": "Soft colloids for complex interfacial assemblies: The design of complex materials and the formation of specific patterns often\narise from the properties of the individual building blocks. In this respect,\ncolloidal systems offer a unique opportunity because nowadays they can be\nsynthesized in the laboratory with many different shapes and features. Hence,\nan appropriate choice of the particle characteristics makes it possible to\ngenerate macroscopic structures with desired properties. The versatility of\ncolloids can also be explored in two dimensions, using liquid-liquid or\nair-liquid interfaces as privileged substrates where they can adsorb and\nself-assemble. Besides being innovative model systems for fundamental studies,\nthe great interest of the scientific community is also technological and\napplicative, since colloidal-scale surface patterns are very promising for\nexample in photonics or biosensing. In a recent study published in PNAS, Menath\nand coworkers combine these elements and exploit core-shell colloids,\nconsisting of a silica core and a soft, non-crosslinked polymer shell, to make\nan important step forward in controlling the assembly of complex structures at\nan interface."
    },
    {
        "anchor": "Capillary pressure of van der Waals liquid nanodrops: The dependence of the surface tension on a nanodrop radius is important for\nthe new-phase formation process. It is demonstrated that the famous Tolman\nformula is not unique and the size-dependence of the surface tension can\ndistinct for different systems. The analysis is based on a relationship between\nthe surface tension and disjoining pressure in nanodrops. It is shown that the\nvan der Waals interactions do not affect the new-phase formation thermodynamics\nsince the effect of the disjoining pressure and size-dependent component of the\nsurface tension cancel each other.",
        "positive": "Equilibrium interfacial free energies and Turnbull coefficient for bcc\n  crystallizing colloidal charged sphere suspensions: We extend previous analysis of data for the melt-nucleus interfacial free\nenergy, $\\gamma$, gained from optical experiments on suspensions of charged\ncolloidal spheres, which crystallize with body centred cubic (bcc) crystal\nstructures. Compiling data from five pure species with different\npolydispersities and one binary mixture, we find the equilibrium melt-crystal\ninterfacial energy to be considerably larger than the hard sphere reference\nvalue. Both this quantity and the entropy of freezing decrease with increasing\npolydispersity. Moreover, we give a first experimental determination of the\nTurnbull coefficient for a bcc crystallizing material. The observed value\n$C_{T, bcc} \\approx 0.3$ agrees well with theoretical expectations for bcc\nsystems with short to medium ranged interactions."
    },
    {
        "anchor": "Breakdown of electroneutrality in nanopores: Ion transport in extremely narrow nanochannels has gained increasing interest\nin recent years due to its unique physical properties, and the technological\nadvances that allow us to study them. It is tempting to approach this regime\nwith the tools and knowledge developed for wider microfluidic devices and use\ncontinuum models like the Poisson-Nernst-Planck equation. However, it turns out\nthat some of the most basic principles we take for granted in a large system,\nsuch as electroneutrality, can breakdown under extreme confinement. We show\nthat in a truly one-dimensional system, interacting with three-dimensional\nelectrostatic interactions, the screening length is exponentially large in\nionic spacing, and can easily exceed the macroscopic length of a nanotube.\nWithout screening, electroneutrality is broken, and ionic transport can behave\nin a completely different way. In this work, we build a theoretical framework\nfor electroneutrality breakdown in a one-dimensional nanopore and show how it\nprovides an elegant interpretation for the peculiar scaling observed in\nexperimental measurements of ionic conductance in carbon nanotubes.",
        "positive": "Crumple-Origami Transition for Twisting Cylindrical Shells: Origami and crumpling are two extreme tools to shrink a 3-D shell. In the\nshrink/expand process, the former is reversible due to its topological\nmechanism, while the latter is irreversible because of its random-generated\ncreases. We observe a morphological transition between origami and crumple\nstates in a twisted cylindrical shell. By studying the regularity of crease\npattern, acoustic emission and energetics from experiments and simulations, we\ndevelop a model to explain this transition from frustration of geometry that\ncauses breaking of rotational symmetry. In contrast to solving von\nKarman-Donnell equations numerically, our model allows derivations of analytic\nformula that successfully describe the origami state. When generalized to\ntruncated cones and polygonal cylinders, we explain why multiple and/or\nreversed crumple-origami transitions can occur."
    },
    {
        "anchor": "Role of bond orientational order in the crystallization of hard spheres: With computer simulations of the hard sphere model, we examine in detail the\nmicroscopic pathway connecting the metastable melt to the emergence of\ncrystalline clusters. In particular we will show that the nucleation of the\nsolid phase does not follow a two-step mechanism, where crystals form inside\ndense precursor regions. On the contrary, we will show that nucleation is\ndriven by fluctuations of orientational order, and not by the density\nfluctuations. By considering the development of the pair-excess entropy inside\ncrystalline nuclei, we confirm that orientational order precedes positional\norder. These results are at odd with the idea of a two-step nucleation\nmechanism for fluids without a metastable liquid-liquid phase separation. Our\nstudy suggests the pivotal role of bond orientational ordering in triggering\ncrystal nucleation.",
        "positive": "Biaxial Nematics of Hard Cuboids in an External Field: We investigate the phase behavior of colloidal suspensions of board-like\nparticles under the effect of an external field and assess the still disputed\noccurrence of the biaxial nematic (N$_\\text{B}$) liquid crystal phase. The\nexternal field promotes the rearrangement of the initial isotropic (I) or\nuniaxial nematic (N$_\\text{U}$) phase and the formation of the N$_\\text{B}$\nphase. In particular, very weak field strengths are sufficient to spark a\ndirect I-N$_\\text{B}$ or N$_\\text{U}$-N$_\\text{B}$ phase transition at the\nself-dual shape, where prolate and oblate particle geometries fuse into one. By\ncontrast, forming the N$_\\text{B}$ phase at any other geometry requires\nstronger fields and thus reduces the energy efficiency of the phase\ntransformation. Our simulation results show that self-dual shaped board-like\nparticles with moderate anisotropy are able to form N$_\\text{B}$ liquid\ncrystals under the effect of a surprisingly weak external stimulus and suggest\na path to exploit low-energy uniaxial-to-biaxial order switching."
    },
    {
        "anchor": "Role of the first coordination shell in determining the equilibrium\n  structure and dynamics of simple liquids: The traditional view that the physical properties of a simple liquid are\ndetermined primarily by its repulsive forces was recently challenged by\nBerthier and Tarjus, who showed that in some cases ignoring the attractions\nleads to large errors in the dynamics [L. Berthier and G. Tarjus, Phys. Rev.\nLett. 103, 170601 (2009); J. Chem. Phys. 134, 214503 (2011)]. We present\nsimulations of the standard Lennard-Jones liquid at several condensed-fluid\nstate points, including a fairly low density state and a very high density\nstate, as well as simulations of the Kob-Andersen binary Lennard-Jones mixture\nat several temperatures. By varying the range of the forces, results for the\nthermodynamics, dynamics, and structure show that the determining factor for\ngetting the correct statics and dynamics is not whether or not the attractive\nforces {\\it per se} are included in the simulations. What matters is whether or\nnot interactions are included from all particles within the first coordination\nshell (FCS) - the attractive forces can thus be ignored, but only at extremely\nhigh densities. The recognition of the importance of a local shell in condensed\nfluids goes back to van der Waals; our results confirm this idea and thereby\nthe basic picture of the old hole- and cell theories for simple condensed\nfluids.",
        "positive": "Critical behavior for impact fragmentation of spherical solid bodies\n  sensitive to strain rate: We consider the impact fragmentation of two spherical solid bodies sensitive\nto strain rate in a three-dimensional (3D) setting. We use both dimensional\nanalysis and numerical simulations by smoothed-particle hydrodynamics (SPH)\nmethod to shed light on this problem. The key point of the work is the\nassumption of complete self-similarity of the problem under consideration with\nrespect to the effective strain rate parameter Eeff, which is verified by\nnumerical simulations. As a result we consider the two cases corresponding to\nthe high-velocity Eeff >> 1, and low-velocity Eeff <<1 loading. The size of the\nsystem may be characterized by the total number of the SPH particles Ntot\napproximating each sphere. It is shown that for finite system the critical\nvelocity of fragmentation at high-velocity loading exceeds that at low-velocity\nloading . With an unlimited increase in the system size these velocities become\nthe same. It is shown that the critical velocity of fragmentation depend on the\nsystem size in a quadratic manner, i.e. Vc^2 -Vc(inf)^2 ~ Ntot ^(1/3nu) where\nnu is a correlation length exponent."
    },
    {
        "anchor": "Classification of mobile- and immobile-molecule timescales for the\n  Stokes-Einstein and Stokes-Einstein-Debye relations in supercooled water: Molecular dynamics simulations have been performed on TIP4P/2005 supercooled\nwater to investigate the molecular diffusion and shear viscosity at various\ntimescales and assess the Stokes-Einstein (SE) and Stokes-Einstein-Debye (SED)\nrelations. For this purpose, we calculated various time correlation functions,\nsuch as the mean-squared displacement, stress relaxation function, density\ncorrelation function, hydrogen-bond correlation function, rotational\ncorrelation function of molecular orientation, non-Gaussian parameter, and\nfour-point correlation function. Our study of the SE and SED relations\nindicates that the transport coefficients and timescales obtained using these\ntime correlation functions may be classified into two distinct classes: those\ngoverned by either mobile or immobile molecules, due to dynamical\nheterogeneity. In particular, we show that the stress relaxation time,\nhydrogen-bond lifetime, and large-angle rotational relaxation time are coupled\nwith translational diffusion, and are characterized by mobile molecules. In\ncontrast, the structural $\\alpha$-relaxation time, small-angle rotational\nrelaxation time, and characteristic timescales of four-point correlation\nfunctions are decoupled with translational diffusion, and are governed by\nimmobile molecules. This decoupling results in a violation of the SE relation.\nThese results indicate that the identification of timescales that appropriately\ncharacterize transport coefficients, such as translational diffusion constant\nand shear viscosity, provides a deep insight into the violation of the SE and\nSED relations in glass-forming liquids.",
        "positive": "Microscopic flows of suspensions of the green non-motile Chlorella\n  micro-alga at various volume fractions: applications to intensified photo bio\n  reactors: An experimental study of flows of the green non-motile Chlorella micro-alga\nin a plane microchannel is presented. Depending on the value of the cell volume\nfraction, three distinct flow regimes are observed. For low values of the cell\nvolume fraction a Newtonian flow regime characterised by a Poiseuille like flow\nfield, absence of wall slip and hydrodynamic reversibility of the flow states\nis observed. For intermediate values of the cell volume fraction, the flow\nprofiles are consistent with a Poiseuille flow of a shear thinning fluid in the\npresence of slip at the channel's wall. For even larger cell volume fractions,\na yield stress like behaviour manifested through the presence of a central\nsolid plug is observed. Except for the Newtonian flow regime, a strong\nhydrodynamic irreversibility of the flow and wall slip are found. The\ncalculation of the wall shear rate and wall stress based on the measured flow\nfields allows one to identify the mechanisms of wall slip observed in the shear\nthinning and yield stress regimes."
    },
    {
        "anchor": "Nonreciprocity as a generic route to traveling states: We examine a non-reciprocally coupled dynamical model of a mixture of two\ndiffusing species. We demonstrate that nonreciprocity, which is encoded in the\nmodel via antagonistic cross diffusivities, provides a generic mechanism for\nthe emergence of traveling patterns in purely diffusive systems with\nconservative dynamics. In the absence of non-reciprocity, the binary fluid\nmixture undergoes a phase transition from a homogeneous mixed state to a\ndemixed state with spatially separated regions rich in one of the two\ncomponents. Above a critical value of the parameter tuning non-reciprocity, the\nstatic demixed pattern acquires a finite velocity, resulting in a state that\nbreaks both spatial and time translational symmetry, as well as the reflection\nparity of the static pattern. We elucidate the generic nature of the transition\nto traveling patterns using a minimal model that can be studied analytically.\nOur work has direct relevance to nonequilibrium assembly in mixtures of\nchemically interacting colloids that are known to exhibit non-reciprocal\neffective interactions, as well as to mixtures of active and passive agents\nwhere traveling states of the type predicted here have been observed in\nsimulations. It also provides insight on transitions to traveling and\noscillatory states seen in a broad range of nonreciprocal systems with\nnon-conservative dynamics, from reaction-diffusion and prey-predators models to\nmultispecies mixtures of microorganisms with antagonistic interactions.",
        "positive": "Failure to replicate long-range tunable attractions in colloidal system: Recently, a temperature-sensitive long-range attraction colloidal system\nexhibiting melting and pre-melting of colloidal crystals has been reported by\nLi et al.[1]. If it is true, it would be an ideal system to simulate a board\nrange of phase transitions happening in atomic systems. We have reanalyzed\ntheir data in [1] and have discovered great inconsistency in their radial\ndistribution functions g(r) and pair potentials u(r). We have tried to\nreproduce their experimental results but failed to find the\ntemperature-sensitive long rang attraction as reported by Li et al. Based on\nour experimental observations, We conclude that the melting and premelting\nreported in their paper are non-equilibrium phenomena caused by non-uniform\ntemperature in the samples of Li et al.."
    },
    {
        "anchor": "Statistical theory of fluids with a complex electric structure:\n  Application to solutions of soft-core dipolar particles: Based on the thermodynamic perturbation theory (TPT) and the Random phase\napproximation (RPA), we present a statistical theory of solutions of\nelectrically neutral soft molecules, every of which is modelled as a set of\nsites that interact with each other through the potentials, presented as the\nsum of the Coulomb potential and arbitrary soft-core potential. As an\napplication of our formalism, we formulate a general statistical theory of\nsolution of the soft-core dipolar particles. For the latter, we obtain a new\nanalytical relation for the screening function. As a special case, we apply\nthis theory to describing the phase behavior of a solution of the dipolar\nparticles interacting with each other in addition to the electrostatic\npotential through the repulsive Gaussian potential -- Gaussian core dipolar\nmodel (GCDM). Using the obtained analytic expression for the total free energy\nof the GCDM, we obtain the liquid-liquid phase separation with an upper\ncritical point. The developed formalism could be used as a general framework\nfor the coarse-grained description of thermodynamic properties of solutions of\nmacromolecules, such as proteins, betaines, polypeptides, etc.",
        "positive": "Designing colloidal ground state patterns using short-range isotropic\n  interactions: DNA-coated colloids are a popular model system for self-assembly through\ntunable interactions. The DNA-encoded linkages between particles theoretically\nallow for very high specificity, but generally no directionality or long-range\ninteractions. We introduce a two-dimensional lattice model for particles of\nmany different types with short-range isotropic interactions that are pairwise\nspecific. For this class of models, we address the fundamental question whether\nit is possible to reliably design the interactions so that the ground state is\nunique and corresponds to a given crystal structure. First, we determine lower\nlimits for the interaction range between particles, depending on the complexity\nof the desired pattern and the underlying lattice. Then, we introduce a\n`recipe' for determining the pairwise interactions that exactly satisfies this\nminimum criterion, and we show that it is sufficient to uniquely determine the\nground state for a large class of crystal structures. Finally, we verify these\nresults using Monte Carlo simulations."
    },
    {
        "anchor": "2D granular flows with the $\u03bc(I)$ rheology and side walls friction: a\n  well balanced multilayer discretization: We present here numerical modelling of granular flows with the $\\mu(I)$\nrheology in confined channels. The contribution is twofold: (i) a model to\napproximate the Navier-Stokes equations with the $\\mu(I)$ rheology through an\nasymptotic analysis. Under the hypothesis of a one-dimensional flow, this model\ntakes into account side walls friction; (ii) a multilayer discretization\nfollowing Fern\\'andez-Nieto et al. (J. Fluid Mech., vol. 798, 2016, pp.\n643-681). In this new numerical scheme, we propose an appropriate treatment of\nthe rheological terms through a hydrostatic reconstruction which allows this\nscheme to be well-balanced and therefore to deal with dry areas. Based on\nacademic tests, we first evaluate the influence of the width of the channel on\nthe normal profiles of the downslope velocity thanks to the multilayer approach\nthat is intrinsically able to describe changes from Bagnold to S-shaped (and\nvice versa) velocity profiles. We also check the well balance property of the\nproposed numerical scheme. We show that approximating side walls friction using\nsingle-layer models may lead to strong errors. Secondly, we compare the\nnumerical results with experimental data on granular collapses. We show that\nthe proposed scheme allows us to qualitatively reproduce the deposit in the\ncase of a rigid bed (i. e. dry area) and that the error made by replacing the\ndry area by a small layer of material may be large if this layer is not thin\nenough. The proposed model is also able to reproduce the time evolution of the\nfree surface and of the flow/no-flow interface. In addition, it reproduces the\neffect of erosion for granular flows over initially static material lying on\nthe bed. This is possible when using a variable friction coefficient $\\mu(I)$\nbut not with a constant friction coefficient.",
        "positive": "Constrained metric variations and emergent equilibrium surfaces: Any surface is completely characterized by a metric and a symmetric tensor\nsatisfying the Gauss-Codazzi-Mainardi equations (GCM), which identifies the\nlatter as its curvature. We demonstrate that physical questions relating to a\nsurface described by any Hamiltonian involving only surface degrees of freedom\ncan be phrased completely in terms of these tensors without explicit reference\nto the ambient space: the surface is an emergent entity. Lagrange multipliers\nare introduced to impose GCM as constraints on these variables and equations\ndescribing stationary surface states derived. The behavior of these multipliers\nis explored for minimal surfaces, showing how their singularities correlate\nwith surface instabilities."
    },
    {
        "anchor": "On the quasi-static effective behaviour of poroelastic media containing\n  elastic inclusions: The aim of the present study is to derive the effective quasi-static\nbehaviour of a composite medium, made of a poroelastic matrix containing\nelastic impervious inclusions. For this purpose, the asymptotic homogenisation\nmethod is used. On the local scale, the governing equations include Biot's\nmodel of poroelasticity in the porous matrix and Navier equations in the\ninclusions, with elastic properties of the same order of magnitude. Biot's\ndiphasic model of poroelasticity is obtained on the macroscopic scale, but with\neffective parameters that are strongly impacted by the distribution of\ninclusions, even at low volume fraction. The impact on fluid flow is strictly\ngeometrical, showing that the inclusions do not play the role of a porous\nnetwork.",
        "positive": "Stability of the interface of an isotropic active fluid: We study the linear stability of an isotropic active fluid in three different\ngeometries: a film of active fluid on a rigid substrate, a cylindrical thread\nof fluid, and a spherical fluid droplet. The active fluid is modeled by the\nhydrodynamic theory of an active nematic liquid crystal in the isotropic phase.\nIn each geometry, we calculate the growth rate of sinusoidal modes of\ndeformation of the interface. There are two distinct branches of growth rates;\nat long wavelength, one corresponds to the deformation of the interface, and\none corresponds to the evolution of the liquid crystalline degrees of freedom.\nThe passive cases of the film and the spherical droplet are always stable. For\nthese geometries, a sufficiently large activity leads to instability. Activity\nalso leads to propagating damped or growing modes. The passive cylindrical\nthread is unstable for perturbations with wavelength longer than the\ncircumference. A sufficiently large activity can make any wavelength unstable,\nand again leads to propagating damped or growing modes."
    },
    {
        "anchor": "Phase diagram for diblock copolymer melts under cylindrical confinement: We extensively study the phase diagram of a diblock copolymer melt confined\nin a cylindrical nanopore using real-space self-consistent mean-field theory.\nWe discover a rich variety of new two-dimensional equilibrium structures that\nhave no analog in the unconfined system. These include non-hexagonally\ncoordinated cylinder phases and structures intermediate between lamellae and\ncylinders. We map the stability regions and phase boundaries for all the\nstructures we find. As the pore radius is decreased, the pore accommodates\nfewer cylindrical domains and structural transitions occur as cylinders are\neliminated. Our results are consistent with experiments, but we also predict\nphases yet to be observed.",
        "positive": "Generic transient memory formation in disordered systems with noise: Out-of-equilibrium disordered systems may form memories of external driving\nin a remarkable fashion. The system \"remembers\" multiple values from a series\nof training inputs yet \"forgets\" nearly all of them at long times despite the\ninputs being continually repeated. Here, learning and forgetting are\ninseparable aspects of a single process. The memory loss may be prevented by\nthe addition of noise. We identify a class of systems with this behavior,\ngiving as an example a model of non-brownian suspensions under cyclic shear."
    },
    {
        "anchor": "Reply to Chen and Ni on \"Explicit analytical solution for random close\n  packing in $d=2$ and $d=3$\": We show that very clear answers to the queries raised by D. Chen and R. Ni in\ntheir Comment on our recent paper [A. Zaccone, Phys. Rev. Lett. 128, 028002\n(2022)] can be found in our original paper already. The paper [A. Zaccone,\nPhys. Rev. Lett. 128, 028002 (2022)] is free of mathematical errors, as anyone\ncan easily verify, and all the assumptions were carefully, and critically\ndiscussed in the paper.",
        "positive": "A unit-cell approach to the nonlinear rheology of biopolymer solutions: We propose a nonlinear extension of the standard tube model for semidilute\nsolutions of freely-sliding semiflexible polymers. Non-affine filament\ndeformations at the entanglement scale, the renormalisation of direct\ninteractions by thermal fluctuations, and the geometry of large deformations\nare systematically taken into account. The stiffening response predicted for\nathermal solutions of stiff rods is found to be thermally suppressed. Instead,\nwe obtain a broad linear response regime, supporting the interpretation of\nshear stiffening at finite frequencies in polymerised actin solutions as\nindicative of coupling to longitudinal modes. We observe a destabilizing effect\nof large strains (about 100%), suggesting shear banding as a plausible\nexplanation for the widely observed catastrophic collapse of in-vitro\nbiopolymer solutions, usually attributed to network damage. In combination with\nfriction-type interactions, our analysis provides an analytically tractable\nframework to address the nonlinear viscoplasticity of biological tissue on a\nmolecular basis."
    },
    {
        "anchor": "Induced glassy behavior in the melt of glycerol and aerosil dispersions: A high-resolution calorimetric spectroscopy study has been performed on pure\nglycerol and colloidal dispersions of an aerosil in glycerol covering a wide\nrange of temperatures from 300 K to 380 K, deep in the liquid phase of\nglycerol. The colloidal glycerol+aerosil samples with 0.05, 0.10, and 0.20 mass\nfraction of aerosil reveal glassy, activated dynamics at temperatures well\nabove the $T_g$ of the pure glycerol. The onset of glass-like behavior appears\nto be due to the structural frustration imposed by the silica gel on the\nglycerol liquid. The aerosil gel increases the net viscosity of the mixture,\nplacing the sample effectively at a lower temperature thus inducing a glassy\nstate. Given the onset of this behavior at relatively low aerosil density\n(large mean-void length compared to the size of a glycerol molecule), this\ninduced glassy behavior is likely due to a collective mode of glycerol\nmolecules. The study of frustrated glass-forming systems may be a unique avenue\nfor illuminating the physics of glasses.",
        "positive": "Kinetics of condensation of flexible polyelectrolytes in poor solvents:\n  effects of solvent quality, valence and size of counterions: The collapse kinetics of strongly charged polyelectrolytes in poor solvents\nis investigated by Langevin simulations and scaling arguments. The rate of\ncollapse increases sharply as the valence of counterions, z, increases from one\nto four. The combined system of the collapsed chain and the condensed\ncounterions forms a Wigner crystal when the solvent quality is not too poor\nprovided z >= 2. For very poor solvents the morphology of the collapsed\nstructure resembles a Wigner glass. For a fixed z and quality of the solvent\nthe efficiency of collapse decreases dramatically as the size of the counterion\nincreases. A valence dependent diagram of states in poor solvents is derived."
    },
    {
        "anchor": "Coupled DEM-LBM method for the free-surface simulation of heterogeneous\n  suspensions: The complexity of the interactions between the constituent granular and\nliquid phases of a suspension requires an adequate treatment of the\nconstituents themselves. A promising way for numerical simulations of such\nsystems is given by hybrid computational frameworks. This is naturally done,\nwhen the Lagrangian description of particle dynamics of the granular phase\nfinds a correspondence in the fluid description. In this work we employ\nextensions of the Lattice-Boltzmann Method for non-Newtonian rheology, free\nsurfaces, and moving boundaries. The models allows for a full coupling of the\nphases, but in a simplified way. An experimental validation is given by an\nexample of gravity driven flow of a particle suspension.",
        "positive": "Anomaly in the stability limit of liquid helium 3: We propose that the liquid-gas spinodal line of helium 3 reaches a minimum at\n0.4 K. This feature is supported by our cavitation measurements. We also show\nthat it is consistent with extrapolations of sound velocity measurements.\nSpeedy [J. Phys. Chem. 86, 3002 (1982)] previously proposed this peculiar\nbehavior for the spinodal of water and related it to a change in sign of the\nexpansion coefficient alpha, i. e. a line of density maxima. Helium 3 exhibits\nsuch a line at positive pressure. We consider its extrapolation to negative\npressure. Our discussion raises fundamental questions about the sign of alpha\nin a Fermi liquid along its spinodal."
    },
    {
        "anchor": "Active patterning and asymmetric transport in a model actomyosin network: Cytoskeletal networks, which are essentially motor-filament assemblies, play\na major role in many developmental processes involving structural remodeling\nand shape changes. These are achieved by nonequilibrium self-organization\nprocesses that generate functional patterns and drive intracellular transport.\nWe construct a minimal physical model that incorporates the coupling between\nnonlinear elastic responses of individual filaments and force-dependent motor\naction. By performing stochastic simulations we show that the interplay of\nmotor processes, described as driving anti-correlated motion of the network\nvertices, and the network connectivity, which determines the percolation\ncharacter of the structure, can indeed capture the dynamical and structural\ncooperativity which gives rise to diverse patterns observed experimentally. The\nbuckling instability of individual filaments is found to play a key role in\nlocalizing collapse events due to local force imbalance. Motor-driven\nbuckling-induced node aggregation provides a dynamic mechanism that stabilizes\nthe two dimensional patterns below the apparent static percolation limit.\nCoordinated motor action is also shown to suppress random thermal noise on\nlarge time scales, the two dimensional configuration that the system starts\nwith thus remaining planar during the structural development. By carrying out\nsimilar simulations on a three dimensional anchored network, we find that the\nmyosin-driven isotropic contraction of a well-connected actin network, when\ncombined with mechanical anchoring that confers directionality to the\ncollective motion, may represent a novel mechanism of intracellular transport,\nas revealed by chromosome translocation in the starfish oocyte.",
        "positive": "DNA folding: structural and mechanical properties of the two-angle model\n  for chromatin: We present a theoretical analysis of the structural and mechanical properties\nof the 30-nm chromatin fiber. Our study is based on the two-angle model\nintroduced by Woodcock et al. (Woodcock, C. L., S. A. Grigoryev, R. A.\nHorowitz, and N. Whitaker. 1993. PNAS 90:9021-9025) that describes the\nchromatin fiber geometry in terms of the entry-exit angle of the nucleosomal\nDNA and the rotational setting of the neighboring nucleosomes with respect to\neach other. We explore analytically the different structures that arise from\nthis building principle, and demonstrate that the geometry with the highest\ndensity is close to the one found in native chromatin fibers under\nphysiological conditions. On the basis of this model we calculate mechanical\nproperties of the fiber under stretching. We obtain expressions for the\nstress-strain characteristics which show good agreement with the results of\nrecent stretching experiments (Cui, Y., and C. Bustamante. 2000. PNAS\n97:127-132) and computer simulations (Katritch, V., C. Bustamante, and W. K.\nOlson. 2000. J. Mol. Biol. 295:29-40), and which provide simple physical\ninsights into correlations between the structural and elastic properties of\nchromatin."
    },
    {
        "anchor": "Kinetics of water flow through polymer gel: The water flow through the poly(acrylamide) gel under a constant water\npressure is measured by newly designed apparatus. The time evolution of the\nwater flow in the gel, is calculated based on the collective diffusion model of\nthe polymer network coupled with the friction between the polymer network and\nthe water. The friction coefficient are determined from the equilibrium\nvelocity of water flow. The Young modulus and the Poisson's ratio of the rod\nshape gels are measured by the uni-axial elongation experiments, which\ndetermine the longitudinal modulus independently from the water flow\nexperiments. With the values of the longitudinal modulus and of the friction\ndetermined by the experiments, the calculated results are compared with the\ntime evolution of the flow experiments. We find that the time evolution of the\nwater flow is well described by a single characteristic relaxation time\npredicted by the collective diffusion model coupled with the water friction.",
        "positive": "Influence of salt on membrane rigidity of neu-tral DOPC vesicles: Salt is a very common molecule in aqueous environments but the question of\nwhether the interactions of monovalent ions Na^+ and Cl^- ,with the neutral\nheads of phospholipids are impactful enough to change the membrane rigidity is\nstill a mystery. To provide a resolution to this long simmering debate, we\ninvestigated the dynamics of DOPC vesicles in the fluid phase with increasing\nexternal salt concentration. At higher salt concentrations, we observe an\nincrease in bending rigidity from neutron spin echo spectroscopy (NSE) and an\nincrease in bilayer thickness from small-angle X-ray scattering (SAXS). We\ncompared different models to distinguish membrane undulations, lipid tail\nmotions and the translational diffusion of the vesicles. All the models\nindicate an increase in bending rigidity by a factor of 1.3 to 3.6. We\ndemonstrate that even for t > 10 ns, and for Q > 0.07 1/{\\AA} the observed NSE\nrelaxation spectra is clearly influenced by the translational diffusion of the\nvesicles. For t < 5 ns, the lipid tail motions dominate the intermediate\ndynamic structure factor. As the salt concentration increases this contribution\ndiminishes. We introduced a new time-dependent analysis for the bending\nrigidity that highlights only a limited Zilman-Granek time window where the\nrigidity is physically meaningful."
    },
    {
        "anchor": "Mass-based separation of active Brownian particles in an asymmetric\n  channel: The inertial effects should be considered for micro- and nano-swimmers moving\nin a low-density medium confined by irregular structures that create entropic\nbarriers, where viscous effects are no longer paramount. Here, we present a\nseparation mechanism of self-propelled particles in a two-dimensional\nasymmetric channel, which leads to the drift of particles of different masses\nin opposite directions. In particular, this mechanism is based on the combined\naction of the spatial asymmetry of the channel structure, temporal asymmetry\ninherent in particles dynamics, and an external static force. This work is\nrelevant for potential applications that can be found in the development of\nlab-on-a-chip devices and artificial channels for separating particles of\ndifferent masses.",
        "positive": "A model for colloidal suspension under magnetohydrodynamic conditions: We present a comprehensive model to account for the behavior of suspended\nnanoparticles under magnetohydrodynamic conditions. The Lorentz force not only\ndrags nanoparticle flocs toward the walls reducing the distance between flocs\nresulting a more negative total pair interaction potential energy, but also\nproduces extra magnetic-induced stresses inside a floc leading to a change of\npair interaction distance thus giving rise to a less negative total potential\nenergy. The model explains quite well the recent experimental results showing\nthat magnetic field assists aggregation in laminar or weak turbulent flows, but\nfavors floc disruption in turbulent regime."
    },
    {
        "anchor": "Formation of cluster crystals in an ultra-soft potential model on a\n  spherical surface: We investigate the formation of cluster crystals with multiply occupied\nlattice sites on a spherical surface in systems of ultra-soft particles\ninteracting via repulsive, bounded pair potentials. Not all interactions of\nthis kind lead to clustering: we generalize the criterion devised in C.N. Likos\net al., Phys. Rev. E, 2001, 63, 031206 to spherical systems in order to\ndistinguish between cluster forming systems and fluids which display reentrant\nmelting. We use both DFT and Monte Carlo simulations to characterize the\nbehavior of the system, and obtain semi-quantitative agreement between the two.\nFurthermore, we study the effect of topological frustration on the system due\nto the sphere curvature by comparing the properties of disclinations, i.e.,\nclusters with fewer than six neighbors, and non-defective clusters.\nDisclinations are shown to be less stable, contain fewer particles, and be\ncloser to their neighbors than other lattice points: these properties are\nexplained on the basis of geometric and energetic considerations.",
        "positive": "Geometry-guided colloidal interactions and self-tiling of elastic\n  dipoles formed by truncated pyramid particles in liquid crystals: The progress of realizing colloidal structures mimicking natural forms of\norganization in condensed matter is inherently limited by the availability of\nsuitable colloidal building blocks. To enable new forms of crystalline and\nquasicrystalline self-organization of colloids, we develop truncated pyramidal\nparticles that form nematic elastic dipoles with long-range electrostaticlike\nand geometry-guided low-symmetry short-range interactions. Using a combination\nof nonlinear optical imaging, laser tweezers, and video microscopy, we\ncharacterize colloidal pair interactions and demonstrate unusual forms of\nself-tiling of these particles into crystalline, quasicrystalline, and other\narrays. Our findings are explained using an electrostatics analogy along with\nliquid crystal elasticity and symmetry breaking considerations, potentially\nexpanding photonic and electro-optic applications of colloids."
    },
    {
        "anchor": "Inverse swelling of a hydrophobic polymer in aqueous solution: We address the problem of inverse polymer swelling. This phenomenon, in which\na collapsed polymer chain swells upon decreasing temperature, can be observed\nexperimentally in so-called thermoreversible homopolymers in aqueous solution,\nand is believed to be related to the role of hydrophobicity in protein folding.\nWe consider a lattice-fluid model of water, defined on a body-centered cubic\nlattice, which has been previously shown to account for most thermodynamic\nanomalies of water and of hydrophobic solvation for monomeric solutes. We\nrepresent the polymer as a self-avoiding walk on the same lattice, and\ninvestigate the resulting model at a first order approximation level,\nequivalent to the exact calculation on a Husimi lattice. Depending on\ninteraction parameters and applied pressure, the model exhibits first and/or\nsecond order swelling transitions upon decreasing temperature.",
        "positive": "Instantaneous Normal Modes Reveal Structural Signatures for the\n  Herschel-Bulkley Rheology in Sheared Glasses: The Herschel-Bulkley law, a universal constitutive relation, has been\nempirically known to be applicable to a vast range of soft materials, including\nsheared glasses. Although the Herschel- Bulkley law has attracted public\nattention, its structural origin has remained an open question. In this letter,\nby means of atomistic simulation of binary Lennard-Jones glasses, we report\nthat the instantaneous normal modes with negative eigenvalues, or so-called\nimaginary modes, serve as the structural signatures for the Herschel-Bulkley\nrheology in sheared glasses."
    },
    {
        "anchor": "Finite indentation of highly curved elastic shells: Experimentally measuring the elastic properties of thin biological surfaces\nis non-trivial, particularly when they are curved. One technique that may be\nused is the indentation of a thin sheet of material by a rigid indenter, whilst\nmeasuring the applied force and displacement. This gives immediate information\non the fracture strength of the material (from the force required to puncture),\nbut it is also theoretically possible to determine the elastic properties by\ncomparing the resulting force-displacement curves with a mathematical model.\nExisting mathematical studies generally assume that the elastic surface is\ninitially flat, which is often not the case for biological membranes. We\npreviously outlined a theory for the indentation of curved isotropic,\nincompressible, hyperelastic membranes (with no bending stiffness) which breaks\ndown for highly curved surfaces, as the entire membrane becomes wrinkled. Here\nwe introduce the effect of bending stiffness, ensuring that energy is required\nto change the shell shape without stretching, and find that commonly neglected\nterms in the shell equilibrium equation must be included. The theory presented\nhere allows for the estimation of shape- and size-independent elastic\nproperties of highly curved surfaces via indentation experiments, and is\nparticularly relevant for biological surfaces.",
        "positive": "Pore-Spanning Lipid Membrane under Indentation by a Probe Tip: a\n  Molecular Dynamics Simulation Study: We study the indentation of a free-standing lipid membrane suspended over a\nnanopore on a hydrophobic substrate by means of molecular dynamics simulations.\nWe find that in the course of indentation, the membrane bends at the point of\ncontact, and the fringes of the membrane glide downward intermittently along\nthe pore edges and stop gliding when the fringes reach the edge bottoms. The\nbending continues afterwards, and the large strain eventually induces a phase\ntransition in the membrane, transformed from a bilayered structure to an\ninterdigitated structure. The membrane is finally ruptured when the indentation\ngoes deep enough. Several local physical quantities in the pore regions are\ncalculated, which include the tilt angle of lipid molecules, the nematic order,\nthe included angle and the distance between neighboring lipids. The variations\nof these quantities reveal many detailed, not-yet-specified local structural\ntransitions of lipid molecules under indentation. The force-indentation curve\nis also studied and discussed. The results make connection between the\nmicroscopic structure and the macroscopic properties, and provide deep insight\nin the understanding of the stability of a lipid membrane spanning over a\nnanopore."
    },
    {
        "anchor": "Ultra-high-density local structure of liquid water: The local structure of liquid water plays a key role in determining the\nanomalous properties of water. We run all-atom simulations for three\nmicroscopic water models, and use multiple order parameters to analyse the\nlocal structure of water. We identify three types of local structures. In\naddition to the well known low-density-liquid and high-density-liquid\nstructures, the newly identified third type possesses an ultra high density and\novercoordinated H-bonds. The existence of this third type decreases the rate of\ntransition from the high-density-structure to low-density-structure and\nincreases the rate of the reverse one, leading to the enhancement of the\nhigh-density-structure stability.",
        "positive": "Binding of Oppositely Charged Membranes and Membrane Reorganization: We consider the electrostatic interaction between two rigid membranes, with\ndifferent surface charge densities of opposite sign, across an aqueous solution\nwithout added salt. Exact solutions to the nonlinear Poisson-Boltzmann equation\nare obtained and their physical meaning discussed. We also calculate the\nelectrostatic contribution to the free energy and discuss the renormalization\nof the area per head group of the charged lipids arising from the Coulomb\ninteraction."
    },
    {
        "anchor": "Thermal convection in granular gases with dissipative lateral walls: We consider a granular gas under the action of gravity, fluidized by a\nvibrating base. We show that a horizontal temperature gradient, here induced by\nlimiting dissipative lateral walls (DLW), leads always to a granular thermal\nconvection (DLW-TC) that is essentially different from ordinary buoyancy-driven\nconvection (BD-TC). In an experiment where BD-TC is inhibited, by reducing\ngravity with an inclined plane, we always observe a DLW-TC cell next to each\nlateral wall. Such a cell squeezes towards the nearest wall as the gravity\nand/or the number of grains increase. Molecular dynamics simulations reproduce\nthe experimental results and indicate that at large gravity or number of grains\nthe DLW-TC is barely detectable.",
        "positive": "Nematic order of model goethite nanorods in a magnetic field: We explore the nematic order of model goethite nanorods in an external\nmagnetic field within Onsager-Parsons density functional theory. The goethite\nrods are represented by monodisperse, charged spherocylinders with a permanent\nmagnetic moment along the rod main axis, forcing the particles to align\nparallel to the magnetic field at low field strength. The intrinsic diamagnetic\nsusceptibility anisometry of the rods is negative which leads to a preferred\nperpendicular orientation at higher field strength. It is shown that these\ncounteracting effects may give rise to intricate phase behavior, including a\npronounced stability of biaxial nematic order and the presence of reentrant\nphase transitions and demixing phenomena. The effect of the applied field on\nthe nematic-to-smectic transition will also be addressed."
    },
    {
        "anchor": "Continuum field theory for the deformations of planar kirigami: Mechanical metamaterials exhibit exotic properties at the system level, that\nemerge from the interactions of many nearly rigid building blocks. Determining\nthese emergent properties theoretically has remained an open challenge outside\nof a few select examples. Here, for a large class of periodic and planar\nkirigami, we provide a coarse-graining rule linking the design of the panels\nand slits to the kirigami's macroscale deformations. The procedure gives a\nsystem of nonlinear partial differential equations (PDE) expressing geometric\ncompatibility of angle functions related to the motion of individual slits.\nLeveraging known solutions of the PDE, we present excellent agreement between\nsimulations and experiments across kirigami designs. The results reveal a\nsurprising nonlinear wave-type response persisting even at large boundary\nloads, the existence of which is determined completely by the Poisson's ratio\nof the unit cell.",
        "positive": "Diffraction of a superfluid Fermi gas by an atomic grating: An atomic grating generated by a pulsed standing wave laser field is proposed\nto manipulate the superfluid state in a quantum degenerate gas of fermionic\natoms. We show that in the presence of atomic Cooper pairs, the density\noscillations of the gas caused by the atomic grating exhibit a much longer\ncoherence time than that in the normal Fermi gas. Our result indicates that the\ntechnique of a pulsed atomic grating can be a potential candidate to detect the\natomic superfluid state in a quantum degenerate Fermi gas."
    },
    {
        "anchor": "Minimal model for active particles confined in a two-state micropattern: We propose a minimal model, based on active Brownian particles, for the\ndynamics of cells confined in a two-state micropattern, composed of two\nrectangular boxes connected by a bridge, and investigate the transition\nstatistics. A transition between boxes occurs when the active particle crosses\nthe center of the bridge, and the time between subsequent transitions is the\ndwell time. By assuming that the rotational diffusion time $\\tau$ is a function\nof the position, the main features of the transition statistics observed\nexperimentally are recovered. $\\tau$ controls the transition from a ballistic\nregime at short time scales to a diffusive regime at long time scales, with an\neffective diffusion coefficient proportional to $\\tau$. For small values of\n$\\tau$, the dwell time is determined by the characteristic diffusion timescale\nwhich decays with $\\tau$. For large values of $\\tau$, the interaction with the\nwalls dominates and the particle stays mostly at the corners of the boxes\nincreasing the dwell time. We find that there is an optimal $\\tau$ for which\nthe dwell time is minimal and its value can be tuned by changing the geometry\nof the pattern.",
        "positive": "Micro-mechanical response of the F-actin/Tropomyosin/Troponin complex by\n  optical trapping interferometry: Single-particle optical trapping interferometry (OTI) allows us to detect the\nBrownian motion of a tracer bead immersed in a complex fluid with nanometric\nresolution and in the microsecond time-scale. By OTI, we study suspensions\ncomposed of filamentous actin (F-actin), a classic example of a semiflexible\npolymer, using two different kind of tracers: chemically-inert melamine resin\nand polystyrene depleted particles. One-particle microrheology permits to\ninvestigate the local fluctuations of the polymers in the network, but under\nthe condition of a previous knowledge of the F-actin characteristic lengths in\nrelation with the radius of the probes. In this work, we focus on the power-law\nbehavior of the skeletal thin filament, composed by tropomyosin (Tm) and\ntroponin (Tn) coupled to F-actin, which has a role in the muscle contraction by\nits interaction with myosin. We find that the elastic modulus for the\nF-actin/Tm/Tn complex in the presence of Ca$^{2+}$ is constant until the limit\nof high frequencies, and that the calculated values of the power-law exponent\nare less dispersed than in F-actin alone, which we interpret as a\nmicro-measurement of the filament stabilization."
    },
    {
        "anchor": "Sub-Arrhenius diffusion in a binary colloidal system: The dynamics of binary colloidal mixture subjected to an external potential\nbarrier is investigated using molecular dynamics simulations. The depletion\ninteractions between the potential barrier and larger components of the mixture\nalters the dynamics of the system significantly. The larger particles undergo\nsub-Arrhenius diffusion while smaller particles obey normal Arrhenius\ndiffusion. These results show that quantum phenomena such as tunneling is not\nrequired to have sub-Arrhenius diffusion, in contrast to the general agreement\nin the literature. The depletion interactions between the external potential\nbarrier and larger component increases with decreasing temperature which makes\nthe effective activation energy for barrier crossing temperature dependent\nleading to sub-Arrhenius diffusion.",
        "positive": "Pychastic: Precise Brownian Dynamics using Taylor-It\u014d integrators in\n  Python: In the last decade, Python-powered physics simulations ecosystem has been\ngrowing steadily, allowing greater interoperability, and becoming an important\ntool in numerical exploration of physical phenomena, particularly in soft\nmatter systems. Driven by the need for fast and precise numerical integration\nin colloidal dynamics, here we formulate the problem of Brownian Dynamics (BD)\nin a mathematically consistent formalism of the It\\=o calculus, and develop a\nPython package to assist numerical computations. We show that, thanks to the\nautomatic differentiation packages, the classical truncated Taylor-It\\=o\nintegrators can be implemented without the burden of computing the derivatives\nof the coefficient functions beforehand. Furthermore, we show how to circumvent\nthe difficulties of BD simulations such as calculations of the divergence of\nthe mobility tensor in the diffusion equation and discontinuous trajectories\nencountered when working with dynamics on $S^2$ and $SO(3)$. The resulting\nPython package, Pychastic, is capable of performing BD simulations including\nhydrodynamic interactions at speeds comparable to dedicated implementations in\nlower-level programming languages, but with a much simpler end-user interface."
    },
    {
        "anchor": "Lipid Flip-Flop Driven Mechanical and Morphological Changes in Model\n  Membranes: We study, using dissipative particle dynamics simulations, the effect of\nactive lipid flip-flop on model fluid bilayer membranes. We consider both cases\nof symmetric as well as asymmetric flip-flops. Symmetric flip-flop leads to a\nsteady state of the membrane with an effective temperature higher than that of\nthe equilibrium membrane and an effective surface tension lower than that of\nthe equilibrium membrane. Asymmetric flip-flop leads to transient\nconformational changes of the membrane in the form of bud or blister formation,\ndepending on the flip rate.",
        "positive": "Multiscale Modeling of Binary Polymer Mixtures: Scale Bridging in the\n  Athermal and Thermal Regime: Obtaining a rigorous and reliable method for linking computer simulations of\npolymer blends and composites at different length scales of interest is a\nhighly desirable goal in soft matter physics. In this paper a multiscale\nmodeling procedure is presented for the efficient calculation of the static\nstructural properties of binary homopolymer blends. The procedure combines\ncomputer simulations of polymer chains on two different length scales, using a\nunited atom representation for the finer structure and a highly coarse-grained\napproach on the meso-scale, where chains are represented as soft colloidal\nparticles interacting through an effective potential. A method for combining\nthe structural information by inverse mapping is discussed, allowing for the\nefficient calculation of partial correlation functions, which are compared with\nresults from full united atom simulations. The structure of several polymer\nmixtures is obtained in an efficient manner for several mixtures in the\nhomogeneous region of the phase diagram. The method is then extended to\nincorporate thermal fluctuations through an effective chi parameter. Since the\napproach is analytical, it is fully transferable to numerous systems."
    },
    {
        "anchor": "Molecular insights into the physics of poly(amidoamine)-dendrimer-based\n  supercapacitors: Increasing the energy density in electric double layer capacitors (EDLCs),\nalso known as supercapacitors, remains an active area of research.\nSpecifically, there is a need to design and discover electrode and electrolyte\nmaterials with enhanced electrochemical storage capacity. Here, using fully\natomistic molecular dynamics (MD) simulations, we investigate the performance\nof hyper-branched 'poly(amidoamine) (PAMAM)' dendrimer as an electrolyte and an\nelectrode coating material in a graphene based supercapacitor. We investigate\nthe performance of the capacitor using two different modeling approaches,\nnamely the constant charge method (CCM) and the constant potential method\n(CPM). These simulations facilitated the direct calculation of the charge\ndensity, electrostatic potential and field, and hence the differential\ncapacitance. We found that the presence of the dendrimer in the electrodes and\nthe electrolyte increased the capacitance by about 65.25 % and 99.15 %\nrespectively, compared to the bare graphene electrode based aqueous EDLCs.\nFurther analysis revealed that these increases were due to the enhanced\nelectrostatic screening and reorganization of the double layer structure of the\ndendrimer based electrolyte.",
        "positive": "Unexpected Phenomenology in Particle-Based Ice Absent in Magnetic Spin\n  Ice: While particle-based ices are often considered essentially equivalent to\nmagnet-based spin ices, the two differ essentially in frustration and\nenergetics. We show that at equilibrium particle-based ices correspond exactly\nto spin ices coupled to a background field. In trivial geometries, such a field\nhas no effect, and the two systems are indeed thermodynamically equivalent. In\nother cases, however, the field controls a richer phenomenology, absent in\nmagnetic ices, and still largely unexplored: ice rule fragility, topological\ncharge transfer, radial polarization, decimation induced disorder, and\nglassiness."
    },
    {
        "anchor": "Nanostructured epoxies based on the self-assembly of block copolymers: a\n  new miscible block that can be tailored to different epoxy formulations: Nanostructured thermosets may be obtained by self-assembly of amphiphilic\nblock copolymers in a reactive solvent and fixation of the morphologies by the\ncross-linking reaction. Nanostructuration requires the presence of a bock that\nremains miscible in the polymer during polymerization. The selection of the\nmiscible block depends on the particular system and in some cases (e.g., for\nepoxy-amine network based on diglycidyl ether of bisphenol A, and 4,4'-\ndiaminodiphenylsulfone) it is very difficult to find such a block. In this\nmanuscript it is shown that random copolymers of methyl methacrylate (MMA) and\nN,N-dimethylacrylamide (DMA) containing different molar fractions of DMA, can\nbe used as a miscible block for the nanostructuration of epoxies. The\nmiscibility of the random copolymer during formation of the epoxy network was\nfirst analyzed determining cloud-point conversions as a function of the molar\nfraction of DMA in the copolymer. A thermodynamic model of the phase separation\nwas performed using the Flory-Huggins model and taking the polydispersities of\nboth polymers into account. A single expression of the interaction parameter\nbased on the theory of random copolymers provided a reasonable fitting of the\nexperimental cloud-point curves. The significant increase in the miscibility\nproduced by using small DMA molar fractions in the copolymer was explained by\nthe high negative value of the binary interaction energy between DMA and the\nepoxy-amine solvent, associated to the positive value of the interaction energy\nbetween DMA and MMA units. Block copolymers with poly(n-butyl acrylate) as the\nimmiscible block and the random copolymer P(MMA-co-DMA) as the miscible block\nwere used for the nanostructuration of epoxy networks. The necessary molar\nfraction of DMA in the miscible block to stabilize a dispersion of nanosize\ndomains depended on the fraction of the immiscible block.",
        "positive": "A comparison between active strain and active stress in transversely\n  isotropic hyperelastic materials: Active materials are media for which deformations can occur in absence of\nloads, given an external stimulus. Two approaches to the modeling of such\nmaterials are mainly used in literature, both based on the introduction of a\nnew tensor: an additive stress $\\mathsf{P}_\\text{act}$ in the active stress\ncase and a multiplicative strain $\\mathsf{F}_a$ in the active strain one. Aim\nof this paper is the comparison between the two approaches on simple shears.\nConsidering an incompressible and transversely isotropic material, we design\nconstitutive relations for $\\mathsf{P}_\\text{act}$ and $\\mathsf{F}_a$ so that\nthey produce the same results for a uniaxial deformation along the symmetry\naxis. We then study the two approaches in the case of a simple shear\ndeformation. In a hyperelastic setting, we show that the two approaches produce\ndifferent stress components along a simple shear, unless some necessary\nconditions on the strain energy density are fulfilled. However, such conditions\nare very restrictive and rule out the usual elastic strain energy functionals.\nActive stress and active strain therefore produce different results in shear,\neven if they both fit uniaxial data. Our results show that experimental data on\nthe stress-stretch response on uniaxial deformations are not enough to\nestablish which activation approach can capture better the mechanics of active\nmaterials. We conclude that other types of deformations, beyond the uniaxial\none, should be taken into consideration in the modeling of such materials."
    },
    {
        "anchor": "Investigation of slippery behaviour of lubricating fluid coated smooth\n  hydrophilic surfaces: In the recent years many research groups have studied slippery properties on\nlubricating fluid infused rough surfaces using hydrophobic substrates. These\nsurfaces show excellent slippery behaviour for water and other liquids. Here we\ndemonstrate a simple method to fabricate stable slippery surfaces based on\nsilicone oil coated hydrophilic samples. At room temperature, as prepared\nsamples exhibit non-slippery behaviour due to sinking of water drops inside\nsilicone oil layer because of inherently hydrophilic silicon substrate.\nSubsequent annealing at higher temperatures provides covalent bonding of\nsilicone molecules at silicon surface making the surface hydrophobic which was\nconfirmed by lubricant wash tests. So the silicone oil coated annealed samples\nshow excellent water repellency, very low contact angle hysteresis and very\ngood slippery behavior. But these surfaces show poor oil stability against\ndrops flow due to cloaking of the oil around water drops which can be prevented\nby using drops of larger volume or continuous flow of water.",
        "positive": "The good, the bad and the user in soft matter simulations: Molecular dynamics (MD) simulations have become popular in materials science,\nbiochemistry, biophysics and several other fields. Improvements in\ncomputational resources, in quality of force field parameters and algorithms\nhave yielded significant improvements in performance and reliability. On the\nother hand, no method of research is error free. In this review, we discuss a\nfew examples of errors and artifacts due to various sources and discuss how to\navoid them. Besides bringing attention to artifacts and proper practices in\nsimulations, we also aim to provide the reader with a starting point to explore\nthese issues further. In particular, we hope that the discussion encourages\nresearchers to check software, parameters, protocols and, most importantly,\ntheir own practices in order to minimize the possibility of errors. The focus\nhere is on practical issues."
    },
    {
        "anchor": "Bridging thermal and electrical transport in dielectric nanostructure\n  based polar colloids: Heat and charge transport characteristics of nanocolloids have been bridged\nfrom fundamental analysis. The relationship between the two transport phenomena\nin dielectric nanostructure based polar colloids has been quantitatively\npresented. An extensional intuitive analogy to the Wiedemann Franz law has been\ndrawn. Derived from the fact that mobile electrons transport both heat and\ncharge within metallic crystal structure, the analogy can be extended to\nnanocolloids, wherein the dispersed population act as the major transporter.\nThe analogy allows modeling the relationship between the two phenomena and\nsheds more insight and conclusive evidence that nanoparticle traversal within\nthe fluid domain is the main source of augmented transport phenomena exhibit by\nnanocolloids. Important factors such as the thermal and dielectric responses of\nthe nanocolloid can be quantified and bridged through the semi analytical\nformalism. The theoretical analysis has been validated against experimental\ndata and variant scientific literature and good accuracy has been observed.",
        "positive": "Hexagonal and trigonal quasiperiodic tilings: Exploring nonminimal-rank quasicrystals, which have symmetries that can be\nfound in both periodic and aperiodic crystals, often provides new insight into\nthe physical nature of aperiodic long-range order in models that are easier to\ntreat. Motivated by the prevalence of experimental systems exhibiting aperiodic\nlong-range order with hexagonal and trigonal symmetry, we introduce a generic\ntwo-parameter family of 2-dimensional quasiperiodic tilings with such\nsymmetries. We focus on the special case of trigonal and hexagonal Fibonacci,\nor golden-mean, tilings, analogous to the well studied square Fibonacci tiling.\nWe first generate the tilings using a generalized version of de Bruijn's dual\ngrid method. We then discuss their interpretation in terms of projections of a\nhypercubic lattice from six dimensional superspace. We conclude by\nconcentrating on two of the hexagonal members of the family, and examining a\nfew of their properties more closely, while providing a set of substitution\nrules for their generation."
    },
    {
        "anchor": "Renormalization of Fluctuating Tilted-Hexatic Membranes: We consider the tilted-hexatic Hamiltonian on the fluctuating membranes. A\nrenormalization-group analysis leads us to find two critical regions; one\ncorresponds to the strong coupling regime of the gradient cross coupling, the\nother to the weak coupling regime. In the strong coupling regime, we find the\nlocked tilted-hexatic to liquid phase transition when disclinations and\nvortices unbind simultaneously. On the other hand, in the weak coupling regime\nwe find four phases; the unlocked tilted-hexatic phase, the hexatic phase, the\ntilted phase, and liquid phase. Disclinations and vortices unbind\nindependently. The crinkled-to-crumpled transition of the fluctuating\ntilted-hexatic membranes is also described. The crinkled phase in the strong\ncoupling regime is stiffer than that in the weak coupling regime.",
        "positive": "Tuning of tetrahedrality in a silicon potential yields a series of\n  monatomic (metal-like) glassformers of very high fragility: We obtain monatomic glass formers in simulations by modifying the tetrahedral\ncharacter in a silicon potential to explore a triple point zone between\npotentials favoring diamond (dc) and bcc crystals. dc crystallization is always\npreceded by a polyamorphic transformation of the liquid, and is frustrated when\nthe Kauzmann temperature of the high temperature liquid intersects the\nliquid-liquid coexistence line. The glass forming liquids are extraordinarily\nfragile. Our results suggest that Si and Ge liquids may be vitrified at a\npressure close to the diamond-beta-tin-liquid triple point."
    },
    {
        "anchor": "Self-assembly of finite-sized colloidal aggregates: One of the challenges of self-assembling finite-sized colloidal aggregates\nwith a sought morphology is the necessity of precisely sorting the position of\nthe colloids at the microscopic scale to avoid the formation of off-target\nstructures. Microfluidic platforms address this problem by loading into single\ndroplets the exact amount of colloids entering the targeted aggregate. Using\ntheory and simulations, in this paper, we validate a more versatile design\nallowing us to fabricate different types of finite-sized aggregates, including\ncolloidal molecules or core-shell clusters, starting from finite density\nsuspensions of isotropic colloids in bulk. In our model, interactions between\nparticles are mediated by DNA linkers with mobile tethering points, as found in\nexperiments using DNA oligomers tagged with hydrophobic complexes immersed into\nsupported bilayers. By fine-tuning the strength and the number of the different\ntypes of linkers, we prove the possibility of controlling the morphology of the\naggregates, in particular, the valency of the molecules and the size of the\ncore-shell clusters. In general, our design shows how multivalent interactions\ncan lead to microphase separation in equilibrium conditions.",
        "positive": "Self-subdiffusion in solutions of star-shaped crowders: non-monotonic\n  effects of inter-particle interactions: We examine by extensive computer simulations the self-diffusion of\nanisotropic star like particles in crowded two-dimensional solutions. We\ninvestigate the implications of the area coverage fraction $\\phi$ of the\ncrowders and the crowder-crowder adhesion properties on the regime of transient\nanomalous diffusion. We systematically compute the mean squared displacement\n(MSD) of the particles, their time averaged MSD, as well as the effective\ndiffusion coefficient. The diffusion appears ergodic in the limit of long\ntraces, such that the time averaged MSD converges towards the ensemble averaged\nMSD and features a small residual amplitude spread of the time averaged MSD\nfrom individual trajectories. At intermediate time scales we quantify the\nanomalous diffusion in the system. Also, we show that the translational---but\nnot rotational---diffusivity of the particles $D$ is a non-monotonic function\nof the attraction strength between them. Both diffusion coefficients decrease\nas $D(\\phi)\\sim (1-\\phi/\\phi^*)^2$ with the area fraction $\\phi$ occupied by\nthe crowders. Our results might be applicable to rationalising the experimental\nobservations of non-Brownian diffusion for a number of standard macromolecular\ncrowders used in vitro to mimic the cytoplasmic conditions of living cells."
    },
    {
        "anchor": "Sink vs. tilt penetration into shaken dry granular matter: the role of\n  foundation: We study the behavior of cylindrical objects as they sink into a dry granular\nbed fluidized due to lateral oscillations, in order to shed light on human\nconstructions and other objects. Somewhat unexpectedly, we have found that,\nwithin a large range of lateral shaking powers, cylinders with flat bottoms\nsink vertically, while those with a \"foundation\" consisting in a shallow ring\nattached to their bottom, tilt besides sinking. The latter scenario seems to\ndominate independently from the nature of the foundation when strong enough\nlateral vibrations are applied. We are able to reproduce the observed behavior\nby quasi-2D numerical simulations, and the vertical sink dynamics with the help\nof a Newtonian equation of motion for the intruder.",
        "positive": "Poroelastic longitudinal wave equation for soft living tissues: Making use of the poroelastic theory for hydrated polymeric matrices, the\nultrasound (US) propagation in a gel medium filled by spherical cells is\nstudied . The model describes the connection between the poroelastic structure\nof living means and the propagation behavior of the acoustic waves. The\nequation of fast compressional wave, its phase velocity and its attenuation as\na function of the elasticity, porosity and concentration of the cells into the\ngel external matrix are investigated. The outcomes of the theory agree with the\nmeasurements done on PVA gel scaffolds inseminated by porcine liver cells at\nvarious concentrations. The model is promising in the quantitative non-invasive\nestimation of parameters that could asses the change in the tissue structure,\ncomposition and architecture."
    },
    {
        "anchor": "Frustration-induced internal stresses are responsible for quasilocalized\n  modes in structural glasses: It has been recently shown [E. Lerner, G. D\\\"uring, and E. Bouchbinder, Phys.\nRev. Lett. 117, 035501 (2016)] that the non-phononic vibrational modes of\nstructural glasses at low-frequencies $\\omega$ are quasi-localized and follow a\nuniversal density of states $D(\\omega)\\!\\sim\\!\\omega^4$. Here we show that the\ngapless nature of the observed density of states depends on the existence of\ninternal stresses which generically emerge in glasses due to frustration, thus\nelucidating a basic element underlying this universal behavior. Similarly to\njammed particulate packings, low-frequency modes in structural glasses emerge\nfrom a balance between a local elasticity term and an internal stress term in\nthe dynamical matrix, where the difference between them is orders of magnitude\nsmaller than their typical magnitude. By artificially reducing the magnitude of\ninternal stresses in a computer glass former in three dimensions, we show that\na gap is formed in the density of states below which no vibrational modes\nexist, thus demonstrating the crucial importance of internal stresses. Finally,\nwe show that while better annealing the glass upon cooling from the liquid\nstate significantly reduces its internal stresses, the self-organizational\nprocesses during cooling render the gapless $D(\\omega)\\!\\sim\\!\\omega^4$ density\nof state unaffected.",
        "positive": "Anomalous uniform domain in a twisted nematic cell constructed from\n  micropatterned surfaces: We have discovered an optically uniform type of domain that occurs in Twisted\nNematic (TN) cells that are constructed from substrates chemically patterned\nwith stripes via microcontact printing of Self-Assembled Monolayers (SAM); such\ndomains do not occur in TN cells constructed from uniform substrates. In such a\ncell, the azimuthal anchoring at the substrates is due to the elastic\nanisotropy of the liquid crystal rather than the conventional rubbing\nmechanism. A model is presented that predicts the relative stability of the\ntwisted and anomalous states as a function of the material and design\nparameters."
    },
    {
        "anchor": "Secondary flow in ensembles of non-convex granular particles under shear: Studies of granular materials, both theoretical and experimental, are often\nrestricted to convex grain shapes. We demonstrate that a non-convex grain shape\ncan lead to a qualitatively novel macroscopic dynamics. Spatial crosses\n(hexapods) are continuously sheared in a split-bottom container. Thereby, they\ndevelop a secondary flow profile that is completely opposite to that of\nrod-shaped or lentil-shaped convex grains in the same geometry. The crosses at\nthe surface migrate towards the rotation center and sink there, mimicking a\n`reverse Weissenberg effect'. The observed surface flow field suggests the\nexistence of a radial outward flow in the depth of the granular bed, thus\nforming a convection cell. This flow field is connected with a dimple formed in\nthe rotation center. The effect is strongly dependent on the particle geometry\nand the height of the granular bed.",
        "positive": "Measuring every particle's size from three-dimensional imaging\n  experiments: Often experimentalists study colloidal suspensions that are nominally\nmonodisperse. In reality these samples have a polydispersity of 4-10%. At the\nlevel of an individual particle, the consequences of this polydispersity are\nunknown as it is difficult to measure an individual particle size from\nmicroscopy. We propose a general method to estimate individual particle radii\nwithin a moderately concentrated colloidal suspension observed with confocal\nmicroscopy. We confirm the validity of our method by numerical simulations of\nfour major systems: random close packing, colloidal gels, nominally\nmonodisperse dense samples, and nominally binary dense samples. We then apply\nour method to experimental data, and demonstrate the utility of this method\nwith results from four case studies. In the first, we demonstrate that we can\nrecover the full particle size distribution {\\it in situ}. In the second, we\nshow that accounting for particle size leads to more accurate structural\ninformation in a random close packed sample. In the third, we show that crystal\nnucleation occurs in locally monodisperse regions. In the fourth, we show that\nparticle mobility in a dense sample is correlated to the local volume fraction."
    },
    {
        "anchor": "Fiber networks below the isostatic point: fracture without stress\n  concentration: Crack nucleation is a ubiquitous phenomena during materials failure, because\nstress focuses on crack tips. It is known that exceptions to this general rule\narise in the limit of strong disorder or vanishing mechanical stability, where\nstress distributes over a divergent length scale and the material displays\ndiffusive damage. Here we show, using simulations, that a class of diluted\nlattices displays a new critical phase when they are below isostaticity, where\nstress never concentrates, damage always occurs over a divergent length scale,\nand catastrophic failure is avoided.",
        "positive": "Self-limiting stacks of curvature-frustrated colloidal plates: Roles of\n  intra-particle versus inter-particle deformations: In geometrically frustrated assemblies local inter-subunit misfits propagate\nto intra-assembly strain gradients, giving rise to anomalous self-limiting\nassembly thermodynamics. Here, we use theory and coarse-grained simulation to\nstudy a recently developed class of ``curvamer'' particles, flexible shell-like\nparticles that exhibit self-limiting assembly due to the build up of curvature\ndeformation in cohesive stacks. To address a generic, yet poorly understood\naspect of frustrated assembly, we introduce a model of curvamer assembly that\nincorporates both {\\it intra-particle} shape deformation as well as compliance\nof {\\it inter-particle} cohesive gaps, an effect we can attribute to a {\\it\nfinite range of attraction} between particles. We show that the ratio of\nintra-particle (bending elasticity) to inter-particle stiffness not only\ncontrols the regimes of self-limitation but also the nature of frustration\npropagation through curvamer stacks. We find a transition from uniformly-bound,\ncurvature-focusing stacks at small size to gap-opened, uniformly curved stacks\nat large size is controlled by a dimensionless measure of inter- versus\nintra-curvamer stiffness. The finite range of inter-particle attraction\ndetermines range of cohesion in stacks are self-limiting, a prediction which is\nin strong agreement with numerical studies of our coarse-grained colloidal\nmodel. These predictions provide critical guidance for experimental\nrealizations of frustrated particle systems designed to exhibit self-limitation\nat especially large multi-particle scales."
    },
    {
        "anchor": "Colloquium: Phase transitions in polymers and liquids in electric fields: The structure and thermodynamic state of a system changes under the influence\nof external electric fields. Neutral systems are characterized by their\ndielectric constant epsilon, while charged ones also by their charge\ndistribution. In this Colloquium several phenomena occurring in soft-matter\nsystems in spatially uniform and nonuniform fields are surveyed and the role of\nthe conductivity sigma and the linear or nonlinear dependency of epsilon on\ncomposition are identified. Uniform electric fields are responsible for\nelongation of droplets, for destabilization of interfaces between two liquids,\nand for mixing effects in liquid mixtures. Electric fields, when acting on\nphases with mesoscopic order, also give rise to block copolymer orientation, to\ndestabilization of polymer-polymer interfaces, and to order-order phase\ntransitions. The role of linear and nonlinear dependences of epsilon on\ncomposition will be elucidated in these systems. In addition to the dielectric\nanisotropy, existence of a finite conductivity leads to appearance of large\nstresses when these systems are subject to external fields and usually to a\nreduction in the voltages required for the instabilities or phase transitions\nto occur. Finally, phase transitions which occur in nonuniform fields are\ndescribed and emphasis on the importance of epsilon and sigma is given.",
        "positive": "The Superfluid State of a Bose Liquid as a Superposition of a\n  Single-Particle and Pair Coherent Condensates: One considers the superfluid (SF) state of a Bose liquid with a strong\nrepulsion between bosons, in which at T=0, along with a weak single-particle\nBose-Einstein condensate (BEC), there exists an intensive pair coherent\ncondensate (PCC), analogous to the Cooper condensate in a Fermi liquid with an\nattraction between the fermions. Such a PCC emerges in a system of bosons due\nto an oscillating sign-changing momentum dependence of the Fourier component of\nthe pair interaction potential, which is characteristic of a certain family of\nrepulsion potentials. In such cases, the Fourier component is negative in some\ndomain of nonzero momentum transfer, which corresponds to an effective\nattraction. The collective effects of renormalization (``screening'') of the\ninitial interaction lead to a suppression of the repulsion and an enhancement\nof the effective attraction. It is the ratio of the BEC density to the full\ndensity of the liquid $n_0/n\\ll 1$ that is used as a small parameter---unlike\nin the Bogolyubov theory for a quasi-ideal Bose gas, in which the small\nparameter is the ratio of the number of supracondensate excitations to the\nnumber of particles in an intensive BEC, $(n-n_0)/n_0\\ll 1$. A closed system of\nnonlinear integral equations for the normal and anomalous self-energy parts is\nobtained, in the framework of a renormalized perturbation theory built on\ncombined hydrodynamic and field variables. In the framework of the hard-spheres\nmodel, a spectrum of quasiparticles is obtained, which is in good accordance\nwith the experimental spectrum of elementary excitations in superfluid $^4$He.\nThe question of applicability of the Landau criterion in the absence of quantum\nvortices is discussed."
    },
    {
        "anchor": "Normal contact and friction of rubber with model randomly rough surfaces: We report on normal contact and friction measurements of model multicontact\ninterfaces formed between smooth surfaces and substrates textured with a\nstatistical distribution of spherical micro-asperities. Contacts are either\nformed between a rigid textured lens and a smooth rubber, or a flat textured\nrubber and a smooth rigid lens. Measurements of the real area of contact $A$\nversus normal load $P$ are performed by imaging the light transmitted at the\nmicrocontacts. For both interfaces, $A(P)$ is found to be sub-linear with a\npower law behavior. Comparison to two multi-asperity contact models, which\nextend Greenwood-Williamson (J. Greenwood, J. Williamson, \\textit{Proc. Royal\nSoc. London Ser. A} \\textbf{295}, 300 (1966)) model by taking into account the\nelastic interaction between asperities at different length scales, is\nperformed, and allows their validation for the first time. We find that long\nrange elastic interactions arising from the curvature of the nominal surfaces\nare the main source of the non-linearity of $A(P)$. At a shorter range, and\nexcept for very low pressures, the pressure dependence of both density and area\nof micro-contacts remains well described by Greenwood-Williamson's model, which\nneglects any interaction between asperities. In addition, in steady sliding,\nfriction measurements reveal that the mean shear stress at the scale of the\nasperities is systematically larger than that found for a macroscopic contact\nbetween a smooth lens and a rubber. This suggests that frictional stresses\nmeasured at macroscopic length scales may not be simply transposed to\nmicroscopic multicontact interfaces.",
        "positive": "Stability of three-dimensional icosahedral quasicrystals in\n  multi-component systems: The relative stability of three-dimensional icosahedral quasicrystals in\nmulti-component systems has been investigated based on a coupled-mode\nSwift-Hohenberg model with two-length-scales. A recently developed projection\nmethod, which provides a unified numerical framework to study periodic crystals\nand quasicrystals, is used to compute free energies to high accuracy. Compared\nwith traditional approaches, the advantage of the projection method has been\nalso discussed detailedly. A rigorous and systematical computation demonstrates\nthat three-dimensional icosahedral quasicrystal, two-dimensional decagonal\nquasicrystal are stable phases in such a simple multi-component coupled-mode\nSwift-Hohenberg model. The result extends the multiple length-scales\ninteraction mechanism which can stabilize quasicrystals from single-component\nto multi-component systems."
    },
    {
        "anchor": "Elasticity of a polydisperse hard-sphere crystal: A general Monte Carlo simulation method of calculating the elastic constants\nof polydisperse hard-sphere colloidal crystal was developed. The elastic\nconstants of a size polydisperse hard sphere fcc crystal is calculated. The\npressure and three elastic constants(C11, C12 and C44) increase significantly\nwith the polydispersity. It was also found from extrapolation that there is a\nmechanical terminal polydispersity above which a fcc crystal will be\nmechanically unstable.",
        "positive": "The Micromechanics of Three Dimensional Collagen-I Gels: We study the micromechanics of collagen-I gel with the goal of bridging the\ngap between theory and experiment in the study of biopolymer networks.\nThree-dimensional images of fluorescently labeled collagen are obtained by\nconfocal microscopy and the network geometry is extracted using a 3d network\nskeletonization algorithm. Each fiber is modeled as a worm-like-chain that\nresists stretching and bending, and each cross-link is modeled as torsional\nspring. The stress-strain curves of networks at three different densities are\ncompared to rheology measurements. The model shows good agreement with\nexperiment, confirming that strain stiffening of collagen can be explained\nentirely by geometric realignment of the network, as opposed to entropic\nstiffening of individual fibers. The model also suggests that at small strains,\ncross-link deformation is the main contributer to network stiffness whereas at\nlarge strains, fiber stretching dominates. Since this modeling effort uses\nnetworks with realistic geometries, this analysis can ultimately serve as a\ntool for understanding how the mechanics of fibers and cross-links at the\nmicroscopic level produce the macroscopic properties of the network. While the\nfocus of this paper is on the mechanics of collagen, we demonstrate a framework\nthat can be applied to many biopolymer networks."
    },
    {
        "anchor": "A Cooperative Stochastic Model of Gene Expression: Recent experiments at the level of a single cell have shown that gene\nexpression occurs in abrupt stochastic bursts. Further, in an ensemble of\ncells, the levels of proteins produced have a bimodal distribution. In a large\nfraction of cells, the gene expression is either off or has a high value. We\npropose a stochastic model of gene expression the essential features of which\nare stochasticity and cooperative binding of RNA polymerase. The model can\nreproduce the bimodal behaviour seen in experiments.",
        "positive": "Intruder in a two-dimensional granular system: statics and dynamics of\n  force networks in an experimental system experiencing stick-slip dynamics: In quasi-two-dimensional experiments with photoelastic particles confined to\nan annular region, an intruder constrained to move in a circular path halfway\nbetween the annular walls experiences stick-slip dynamics. We discuss the\nresponse of the granular medium to the driven intruder, focusing on the\nevolution of the force network during sticking periods. Because the available\nexperimental data does not include precise information about individual contact\nforces, we use an approach developed in our previous work (Basak et al, J. Eng.\nMechanics (2021)) based on networks constructed from measurements of the\nintegrated strain magnitude on each particle. These networks are analyzed using\ntopological measures based on persistence diagrams, revealing that force\nnetworks evolve smoothly but in a nontrivial manner throughout each sticking\nperiod, even though the intruder and granular particles are stationary.\nCharacteristic features of persistence diagrams show identifiable changes as a\nslip is approaching, indicating the existence of slip precursors. Key features\nof the dynamics are similar for granular materials composed of disks or\npentagons, but some details are consistently different. In particular, we find\nsignificantly larger fluctuations of the measures computed based on persistence\ndiagrams, and therefore of the underlying networks, for systems of pentagonal\nparticles."
    },
    {
        "anchor": "Snell's Law for Shear Zone Refraction in Granular Materials: We present experiments on slow shear flow in a split-bottom linear shear\ncell, filled with layered granular materials. Shearing through two different\nmaterials separated by a flat material boundary is shown to give narrow shear\nzones, which refract at the material boundary in accordance with Snell's law in\noptics. The shear zone is the one that minimizes the dissipation rate upon\nshearing, i.e.a manifestation of the principle of least dissipation. We have\nprepared the materials as to form a granular lens. Shearing through the lens is\nshown to give a very broad shear zone, which corresponds to fulfilling Snell's\nlaw for a continuous range of paths through the cell.",
        "positive": "Stochastic methods for slip prediction in a sheared granular system: We consider a sheared granular system experiencing intermittent dynamics of\nstick-slip type via discrete element simulations. The considered setup consists\nof a two-dimensional system of soft frictional particles sandwiched between\nsolid walls, one of which is exposed to a shearing force. The slip events are\ndetected using stochastic state space models applied to various measures\ndescribing the system. We show that the measures describing the forces between\nthe particles provide earlier detection of an upcoming slip event than the\nmeasures based solely on the wall movement. By comparing the detection times\nobtained from the considered measures, we observe that a typical slip event\nstarts with a local change in the force network. However, some local changes do\nnot spread globally over the force network. For the changes that become global,\nwe find a sharp critical value for their size. If the size of a global change\nexceeds the critical value, then it triggers a slip event; if it does not, then\na much weaker micro-slip follows. Quantification of the changes in the force\nnetwork is made possible by formulating clear and precise measures describing\ntheir static and dynamic properties."
    },
    {
        "anchor": "Flexo-electricity of the dowser texture: The persistent quasi-planar nematic texture known also as the dowser texture\nis characterized by a 2D unitary vector field d. We show here that the dowser\ntexture is sensitive, in first order, to electric fields. This property is due\nto the flexo-electric polarisation P collinear with d expected from R.B.\nMeyer's considerations on flexo-electricity in nematics. It is pointed out that\ndue to the flexo-electric polarisation nematic monopoles can be manipulated by\nelectric fields of appropriated geometry.",
        "positive": "Geometric effects induce anomalous size-dependent active transport in\n  structured environments: Variations of transport efficiency in structured environments between\ndistinct individuals in actively self-propelled systems is both hard to study\nand poorly understood. Here, we study the transport of a non-tumbling {\\ecoli}\nstrain, an active-matter archetype with intrinsic size variation but fairly\nuniform speed, through a periodic pillar array. We show that long-term\ntransport switches from a trapping dominated state for shorter cells to a much\nmore dispersive state for longer cells above a critical bacterial size set by\nthe pillar array geometry. Using a combination of experiments and modeling, we\nshow that this anomalous size-dependence arises from an enhancement of the\nescape rate from trapping for longer cells caused by nearby pillars. Our\nresults show that geometric effects can lead to size being a sensitive tuning\nknob for transport in structured environments, with implications in general for\nactive matter systems and, in particular, for the morphological adaptation of\nbacteria to structured habitats, spatial structuring of communities and for\nanti-biofouling materials design."
    },
    {
        "anchor": "A kinetic theory of plastic flow in soft glassy materials: A kinetic model for the elasto-plastic dynamics of a flowing jammed material\nis proposed, which takes the form of a non-local -- Boltzmann-like -- kinetic\nequation for the stress distribution function. Coarse-graining this equation\nyields a non-local constitutive law for the flow, introducing as a key dynamic\nquantity the local rate of plastic events. This quantity, interpreted as a\nlocal fluidity, is spatially correlated, with a correlation length diverging in\nthe quasi-static limit, i.e. close to yielding. We predict finite size effects\nin the flow behavior, as well as the absence of an intrinsic local flow curves.\nThese features are supported by recent experimental and numerical observations.",
        "positive": "Information-theoretical measures identify accurate low-resolution\n  representations of protein configurational space: A steadily growing computational power is employed to perform molecular\ndynamics simulations of biological macromolecules, which represents at the same\ntime an immense opportunity and a formidable challenge. In fact, large amounts\nof data are produced, from which useful, synthetic, and intelligible\ninformation has to be extracted to make the crucial step from knowing to\nunderstanding. Here we tackled the problem of coarsening the conformational\nspace sampled by proteins in the course of molecular dynamics simulations. We\napplied different schemes to cluster the frames of a dataset of protein\nsimulations; we then employed an information-theoretical framework, based on\nthe notion of resolution and relevance, to gauge how well the various\nclustering methods accomplish this simplification of the configurational space.\nOur approach allowed us to identify the level of resolution that optimally\nbalances simplicity and informativeness; furthermore, we found that the most\nphysically accurate clustering procedures are those that induce an ultrametric\nstructure of the low-resolution space, consistently with the hypothesis that\nthe protein conformational landscape has a self-similar organisation. The\nproposed strategy is general and its applicability extends beyond that of\ncomputational biophysics, making it a valuable tool to extract useful\ninformation from large datasets."
    },
    {
        "anchor": "Point Defects, Chirality and Singularity Theory in Cholesteric Liquid\n  Crystal Droplets: We develop a theory of point defects in cholesterics and textures in\nspherical droplets with normal anchoring. The local structure of chiral defects\nis described by singularity theory and a smectic-like gradient field\nestablishing a nexus between cholesterics and smectics mediated by their\ndefects. We identify the defects of degree $-2$ and $-3$ observed\nexperimentally with the singularities $D_4^{-}$ and $T_{4,4,4}$, respectively.\nRadial point defects typical of nematics cannot be perturbed into chiral\nstructures with a single handedness by general topological considerations. For\nthe same reasons, the spherical surface frustrates the chirality in a surface\nboundary layer containing regions of both handedness.",
        "positive": "Towards the ideal glass transition by pinning in a dimer-polymer mixture: We use a mixture of a polymer and its dimer to control dynamics in a manner\ninspired by \\emph{pinning} a fraction of the system. In our system of\n$\\alpha$-methyl styrene, where the polymer has a glass transition at higher\ntemperature than the dimer, at intermediate temperatures, the polymer acts to\n\"pin\" the dimer. Within this temperature range, we use differential scanning\ncalorimetry to infer a point-to-set length which we find to be profoundly\ninfluenced by the degree of pinning. We determine the dynamics of the system\nwith dielectric spectroscopy and find that while the dynamics are very\nsubstantially slowed by the \"pinning\", the fragility exhibits only a small\nchange relative to the precision of our measurements. This may indicate that in\nthe approach we have used, fragility has a relatively weak dependence on\nquantities such as the point--to--set length. % than one might expect, However,\nan alternative explanation is that the dimer may act to \\emph{plasticize} the\npolymer and thus open routes to relaxation that may be inaccessible to fully\npinned systems."
    },
    {
        "anchor": "Equilibrium protein adsorption on nanometric vegetable-oil hybrid\n  film/water interface using neutron reflectometry: Nanofilms of thickness of about two nanometers have been formed at the\nair-water interface using functionalized castor oil (ICO) with cross-linkable\nsilylated groups. These hybrid films represent excellent candidates for\nreplacing conventional polymeric materials in biomedical applications, but they\nneed to be optimized in terms of biocompatibility which is highly related to\nprotein adsorption. Neutron reflectivity has been used to study the adsorption\nof two model proteins, bovine serum albumin and lysozyme, at the silylated oil\n(ICO)-water interface in the absence and presence of salt at physiologic ionic\nstrength and pH and at different protein concentrations. These measurements are\ncompared to adsorption at the air-water interface. While salt enhances\nadsorption by a similar degree at the air-water and the oil-water interface,\nthe impact of the oil film is significant, with adsorption at the oil-water\ninterface three-to four-fold higher compared to the air-water interface. Under\nthese conditions, the concentration profiles of the adsorbed layers for both\nproteins indicate multilayer adsorption: The thickness of the outer layer\n(oil-side) is close to the dimension of the minor axis of the protein molecule,\n~ 30 {\\AA}, suggesting a side-way orientation with the long axis parallel to\nthe interface. The inner layer extends to 55-60 {\\AA}. Interestingly, in all\ncases, the composition of oil film remains intact without significant protein\npenetration into the film. The optimal adsorption on these nanofilms, 1.7-2.0\nmg$\\bullet$m-2 , is comparable to the results obtained recently on thick solid\ncross-linked films using quartz crystal microbalance and atomic force\nmicroscopy, showing in particular that adsorption at these ICO film interfaces\nunder standard physiological conditions is non-specific. These results furnish\nuseful information towards the elaboration of vegetable oil-based nanofilms, in\ndirect nanoscale applications or as precursor films in the fabrication of\nthicker macroscopic films for biomedical applications. 2",
        "positive": "Non-equilibrium Anisotropic Phases, Nucleation and Critical Behavior in\n  a Driven Lennard-Jones Fluid: We describe short-time kinetic and steady-state properties of the\nnon--equilibrium phases, namely, solid, liquid and gas anisotropic phases in a\ndriven Lennard-Jones fluid. This is a computationally-convenient\ntwo-dimensional model which exhibits a net current and striped structures at\nlow temperature, thus resembling many situations in nature. We here focus on\nboth critical behavior and details of the nucleation process. In spite of the\nanisotropy of the late--time spinodal decomposition process, earlier nucleation\nseems to proceed by Smoluchowski coagulation and Ostwald ripening, which are\nknown to account for nucleation in equilibrium, isotropic lattice systems and\nactual fluids. On the other hand, a detailed analysis of the system critical\nbehavior rises some intriguing questions on the role of symmetries; this\nconcerns the computer and field-theoretical modeling of non-equilibrium fluids."
    },
    {
        "anchor": "Critical viscoelastic response in jammed solids: We determine the linear viscoelastic response of jammed packings of athermal\nrepulsive viscous spheres, a model for emulsions, wet foams, and soft colloidal\nsuspensions. We numerically measure the complex shear modulus, a fundamental\ncharacterization of the response, and demonstrate that low frequency response\ndisplays dynamic critical scaling near unjamming. Viscoelastic shear response\nis governed by the relaxational eigenmodes of a packing. We use scaling\narguments to explain the distribution of eigenrates, which develops a\ndivergence at unjamming. We then derive the critical exponents characterizing\nresponse, including a vanishing shear modulus, diverging viscosity, and\ncritical shear thinning regime. Finally, we demonstrate that macroscopic\nrheology is sensitive to details of the local viscous force law. By varying the\nratio of normal and tangential damping coefficients, we identify and explain a\nqualitative difference between systems with strong and weak damping of sliding\nmotion. When sliding is weakly damped there is no diverging time scale, no\ndiverging viscosity, and no critical shear thinning regime.",
        "positive": "Flow curves of dense colloidal dispersions: schematic model analysis of\n  the shear-dependent viscosity near the colloidal glass transition: A recently proposed schematic model for the non--linear rheology of dense\ncolloidal dispersions is compared to flow curves measured in suspensions that\nconsist of thermosensitive particles. The volume fraction of this purely\nrepulsive model system can be adjusted by changing temperature. Hence, high\nvolume fractions ($\\phi \\leq 0.63$) can be achieved in a reproducible manner.\nThe quantitative analysis of the flow curves suggests that the theoretical\napproach captures the increase of the low shear viscosity with increasing\ndensity, the shear thinning for increasing shear rate, and the yielding of a\nsoft glassy solid. Variations of the high shear viscosity can be traced back to\nhydrodynamic interactions which are not contained in the present approach but\ncan be incorporated into the data analysis by an appropriate rescaling."
    },
    {
        "anchor": "Effect of pH, surface charge and counter-ions on the adsorption of\n  sodium dodecyl sulfate to the sapphire/solution interface: The role of ionic interactions between sodium dodecyl sulfate, SDS, and\nsapphire surfaces have been studied using specular neutron reflection to\ndetermine the structure and composition of adsorbed surfactant layers.\nIncreasing the pH of the solution from 3 to 9 reduces the adsorption by\nreversing the charge of the alumina. This occurs at lower pH for the R-plane (1\n-1 0 2) than the C-plane (0 0 0 1), corresponding to the different points of\nzero charge. The largest surface excess is about 6.5 micromol m-2, the\nthickness of the adsorbed layer is about 24 Angstrom and it contains roughly\n20% water. The hydrocarbon tails of the surfactant molecules clearly\ninterpenetrate rather than form an ordered bilayer. The structure is similar in\neither pure water or in 0.1 M NaCl when the surfactant is at the respective\ncritical micelle concentration. Different structures were seen with lithium and\ncesium dodecyl sulfate. The CsDS forms dense layers with little or no hydration\nand a surface excess of about 10.5 micromol m-2. The metal cation strongly\ninfluences the hydration of the adsorbed surfactant. An overall picture of\n'flattened micelles' for the structure of the adsorbed layer is observed",
        "positive": "Conformations of entangled semiflexible polymers: entropic trapping and\n  transient non-equilibrium distributions: The tube model is a central concept in polymer physics, and allows to reduce\nthe complex many-filament problem of an entangled polymer solution to a single\nfilament description. We investigate the probability distribution function of\nconformations of confinement tubes and single encaged filaments in entangled\nsemiflexible polymer solution. Computer simulations are developed that mimic\nthe actual dynamics of confined polymers in disordered systems with topological\nconstraints on time scales above local equilibration but well below large scale\nrearrangement of the network. We observe the statistical distribution of\ncurvatures and compare our results to recent experimental findings.\nUnexpectedly, the observed distributions show distinctive differences from free\npolymers even in the absence of excluded volume. Extensive simulations permit\nto attribute these features to entropic trapping in network void spaces. The\ntransient non-equilibrium distributions are shown to be a generic feature in\nquenched-disorder systems on intermediate time scales."
    },
    {
        "anchor": "Loss Factor of Supercooled Water at the Frequencies of 11...180 GHz: The loss factor of supercooled water at the frequencies 11...180 GHz has been\nmeasured. A measuring technique has been proposed, in which wetted nanoporous\nsilicate materials, silica gels, with the mean diameter of the pores being 6-9\nnm, were used to obtain deeply supercooled water. Results have been obtained\nfor the loss factor of supercooled water, close to volume water for its\nproperties, when cooled down to -45 {\\deg}C. To ascertain the mechanism of pore\nwater losses, measurements have been made in the range of temperatures 0...-90\n{\\deg}C. The results obtained have demonstrated the existence of significant\nexcessive losses at the temperatures below -30 {\\deg}C, compared to the results\nof computations based on the known models. To allow mathematical description of\nthe increment loss factor, a new addend has been introduced as a sum of two\nGaussian functions in the formula described in [T. Meissner, F. J. Wentz, IEEE\nTrans. Geosci. Remote Sens. 2004. vol. 42, p. 1836]. One of these functions has\nthe extremum near -45 {\\deg}C, and the second one has the extremum in the range\nof -60...-70 {\\deg}C. Additional attenuation at -45 {\\deg}C is supposed to be\nconnected with the second critical point of water. Attenuation with the center\nin the range of temperatures -60...-70 {\\deg}C is determined by the emergence\nof conductive films at the boundary between the hard matrix and ferroelectric\nice 0. This modification is a transitional form to ice Ih or ice Ic and is\nformed at the temperature below -23 {\\deg}C.",
        "positive": "Control of microswimmers by spiral nematic vortices: transition from\n  individual to collective motion and contraction, expansion, and stable\n  circulation of bacterial swirls: Active systems comprised of self-propelled units show fascinating transitions\nfrom Brownian-like dynamics to collective coherent motion. Swirling of swimming\nbacteria is a spectacular example. This study demonstrates that a nematic\nliquid crystal environment patterned as a spiral vortex controls\nindividual-to-collective transition in bacterial swirls and defines whether\nthey expand or shrink. In dilute dispersions, the bacteria swim along open\nspiral trajectories, following the pre-imposed molecular orientation. The\ntrajectories are nonpolar. As their concentration exceeds some threshold, the\nbacteria condense into unipolar circular swirls resembling stable limit cycles.\nThis collective circular motion is controlled by the spiral angle that defines\nthe splay-to-bend ratio of the background director. Vortices with dominating\nsplay shrink the swirls towards the center, while vortices with dominating bend\nexpand them to the periphery. 45o spiraling vortices with splay-bend parity\nproduce the most stable swirls. All the dynamic scenarios are explained by\nhydrodynamic interactions of bacteria mediated by the patterned passive nematic\nenvironment and by the coupling between the concentration and orientation. The\nacquired knowledge of how to control individual and collective motion of\nmicroswimmers by a nematic environment can help in the development of\nmicroscopic mechanical systems."
    },
    {
        "anchor": "Optical excitations in electroluminescent polymers:\n  poly(para-phenylenevinylene) family: Component of photoexcited states with large spatial extent is investigated\nfor optical absorption spectra of the electroluminescent conjugated polymers by\nusing the intermediate exciton theory. We calculate the ratio of oscillator\nstrengths due to long-range excitons with respect to sum of all the oscillator\nstrengths of the absorption as a function of the monomer number. The oscillator\nstrengths of the long-range excitons in poly(para-phenylene) are smaller than\nthose in poly(para-phenylenevinylene), and those of\npoly(para-phenylenedivinylene) are larger than those in\npoly(para-phenylenevinylene) Such relative variations are explained by the\ndifferences of the number of vinylene units. The oscillator strengths of\nlong-range excitons in poly(di-para-phenylenevinylene) are much larger than\nthose of the above three polymers, due to the increase of number of phenyl\nrings. We also find that the energy position of the almost localized exciton is\nneary the same in the four polymers.",
        "positive": "Uniaxial Compression based Recovery Analyses to Describe\n  Polymer-Specific and Universal Nanoindentation Deformation Phenomena: Sharp tip nanoindentation of glassy polymers is a constrained, localized\nviscoelastoplastic deformation. We interpret this complexity, in terms of the\nwell-understood uniaxial deformation. From the uniaxial compression data in the\nliterature, for PMMA, PC and crosslinked SU-8, we obtain their universal,\nyield-normalized recovery curves, with eps*=eps/eps_y, being one measure of the\ncorresponding strain states (CSS). Nanoindentation recovery is determined from\nthe 2sec constant rate unloading h-P data, modeled by a generalized power-law\n(variable power exponent). Comparing these data-sets, yields the correlation\ncoefficient between the notional nanoindentation strain rate epsdot_N and\nstrain and true strain rate and strain, c=epsdot_N/epsdot_t=eps_N/eps_t. The\nequivalent strain, eps, and the c value for any polymer, are within a narrow\nrange, from the onset of indentation. Combining residual profiles via scanning\nprobe microscopy with mathematical modeling of the indenter tip, provides the\nstrain distribution beneath the tip. CSS measures examined here, indicate\npolymer-specific regions to regions common to glassy polymers, which are\nreached very early in the nanoindentation."
    },
    {
        "anchor": "Advanced Monte Carlo simulation techniques to study polymers under\n  equilibrium conditions: The advances in materials and biological sciences have necessitated the use\nof molecular simulations to study polymers. The Markov chain Monte Carlo\nsimulations enable the sampling of relevant microstates of polymeric systems by\ntraversing paths that are impractical in molecular dynamics simulations.\nSeveral advances in applying Monte Carlo simulations to polymeric systems have\nbeen reported in recent decades. The proposed methods address sampling\nchallenges encountered in studying different aspects of polymeric systems.\nTracking the above advances has become increasingly challenging due to the\nextensive literature generated in the field. Moreover, the incorporation of new\nmethods in the existing Monte Carlo simulation packages is cumbersome due to\ntheir complexity. Identifying the foundational algorithms that are common to\ndifferent methods can significantly ease their implementation and make them\naccessible to the broader simulation community. The present chapter classifies\nthe Monte Carlo methods for polymeric systems based on their objectives and\nstandard features of their algorithms. We begin the article by providing an\noverview of advanced Monte Carlo techniques used for polymeric systems and\ntheir specific applications. We then classify the above techniques into two\nbroad categories: 1) Monte Carlo moves and 2) Advanced sampling schemes. The\nformer category is further divided to distinguish the Monte Carlo moves in the\ncanonical and other ensembles. The advanced sampling schemes attempt to improve\nMonte Carlo sampling via approaches other than Monte Carlo moves. We use the\nabove classification to identify common features of the methods and derive\ngeneral expressions that explain their implementation. Such a strategy can help\nreaders select the methods that are suitable for their study and develop\ncomputer programs that can be easily modified to implement new methods.",
        "positive": "Conductivity of a suspension of nanowires in a weakly conducting medium: We study macroscopic electrical or thermal conductivity of a composite made\nof straight or coiled nanowires suspended in poorly conducting medium. We\nassume that volume fraction of the wires is so large that spaces occupied by\nthem overlap, but there is still enough room to distribute wires isotropically.\nWe found a wealth of scaling regimes at different ratios of conductivities of\nthe wire, $\\sigma_1$ and of the medium, $\\sigma_2$, length of wires, their\npersistent length and volume fraction. There are large ranges of parameters\nwhere macroscopic conductivity is proportional to\n$(\\sigma_{1}\\sigma_{2})^{1/2}$. These results are directly applicable to the\ncalculation of the macroscopic diffusion constant of the nonspecific\nDNA-binding proteins in semidilute DNA solution."
    },
    {
        "anchor": "Revisiting the Saffman-Taylor experiment: imbibition patterns and\n  liquid-entrainment transitions: We revisit the Saffman-Taylor experiment focusing on the forced-imbibition\nregime where the displacing fluid wets the confining walls. We demonstrate a\nnew class of invasion patterns that do not display the canonical fingering\nshapes. We evidence that these unanticipated patterns stem from the\nentrainement of thin liquid films from the moving meniscus. We then\ntheoretically explain how the interplay between the fluid flow at the contact\nline and the interface deformations results in the destabilization of liquid\ninterfaces moving past solid surfaces. In addition, this minimal model conveys\na unified framework which consistently accounts for all the liquid-entrainment\nscenarios that have been hitherto reported.",
        "positive": "Pairwise scattering and bound states of spherical microorganisms: The dynamic interactions between pairs of swimming microorganisms underpin\nthe collective behaviour of larger suspensions, but accurately calculating\npairwise collisions has typically required the use of numerical simulations in\nwhich hydrodynamic interactions are fully resolved. In this paper, we utilise\nanalytical expressions for forces and torques acting on two closely separated\nspherical squirmers -- accurate to second order in the ratio of cell-cell\nspacing to squirmer radius -- in order to calculate their scattering dynamics.\nAttention is limited to squirmers whose orientation vectors lie in the same\nplane. We characterise the outgoing angles of pairs of bottom-heavy squirmers\nin terms of their incoming angles, the squirmer parameter $\\beta$, and the\nstrength of the external gravitational field, discovering transient scattering,\nstationary bound states, pairwise swimming motion, and circular orbits. These\nresults compare well with full numerical solutions obtained using boundary\nelement methods, highlighting the utility of lubrication theory. We expect\nthese results will be useful for the foundations of mesoscale continuum models\nfor suspensions of spherical microorganisms."
    },
    {
        "anchor": "Counterion Condensation on Spheres in the Salt-free Limit: A highly-charged spherical colloid in a salt-free environment exerts such a\npowerful attraction on its counterions that a certain fraction condenses onto\nthe surface of a particle. The degree of condensation depends on the curvature\nof the surface. So, for instance, condensation is triggered on a highly-charged\nsphere only if the radius exceeds a certain critical radius $\\collrad^{*}$.\n$\\collrad^{*}$ is expected to be a simple function of the volume fraction of\nparticles. To test these predictions, we prepare spherical particles which\ncontain a covalently-bound ionic liquid, which is engineered to dissociate\nefficiently in a low-dielectric medium. By varying the proportion of ionic\nliquid to monomer we synthesise nonpolar dispersions of highly-charged spheres\nwhich contain essentially no free co-ions. The only ions in the system are\ncounterions generated by the dissociation of surface-bound groups. We study the\nelectrophoretic mobility of this salt-free system as a function of the colloid\nvolume fraction, the particle radius, and the bare charge density and find\nevidence for extensive counterion condensation. At low electric fields, we\nobserve excellent agreement with Poisson-Boltzmann predictions for counterion\ncondensation on spheres. At high electric fields however, where ion advection\nis dominant, the electrophoretic mobility is enhanced significantly which we\nattribute to hydrodynamic stripping of the condensed layer of counterions from\nthe surface of the particle.",
        "positive": "Enhanced diffusion in finite-size simulations of a fragile diatomic\n  glass former: Using molecular dynamics simulations we investigate the finite-size\ndependence of the dynamical properties of a diatomic supercooled liquid. The\nsimplicity of the molecule permits us to access the microsecond time scale. We\nfind that the relaxation time decreases simultaneously with the strength of\ncooperative motions when the size of the system decreases. While the decrease\nof the cooperative motions is in agreement with previous studies, the decrease\nof the relaxation time opposes what has been reported to date in monatomic\nglass formers and in silica. This result suggests the presence of different\ncompeting physical mechanisms in the relaxation process. For very small box\nsizes the relaxation times behavior reverses itself and increases strongly when\nthe box size decreases, thus leading to a nonmonotonic behavior. This result is\nin qualitative agreement with defect and facilitation theories."
    },
    {
        "anchor": "The impact of contact inhibition on collective cell migration and\n  proliferation: Contact inhibition limits migration and proliferation of cells in cell\ncolonies. We consider a multiphase field model to investigate the growth\ndynamics of a cell colony, composed of proliferating cells. The model takes\ninto account the mechanisms of contact inhibition of locomotion and\nproliferation by local mechanical interactions. We compare non-migrating and\nmigrating cells, in order to provide a quantitative characterization of the\ndynamics and analyse the velocity of the colony boundary for both cases.\nAdditionally, we measure single cell velocities, number of neighbour\ndistributions, as well as the influence of stress and age on positions of the\ncells and with respect to each other. We further compare the findings with\nexperimental data for Madin-Darby canine kidney cells",
        "positive": "Phase separation of active Brownian particles in two dimensions:\n  Anything for a quiet life: Active Brownian particles display self-propelled movement, which can be\nmodelled as arising from a one-body force. Although their interparticle\ninteractions are purely repulsive, for strong self propulsion the swimmers\nphase separate into dilute and dense phases. We describe in detail a recent\ntheory (Phys. Rev. E 100, 052604 (2019); Phys. Rev. Lett. 128, 26802 (2019))\nfor such motility induced phase-separation. Starting from the continuity\nequation and the force density balance, the description is based on four\nsuperadiabatic contributions to the internal force density. Here the\nsuperadiabatic forces are due to the flow in the system and they act on top of\nthe adiabatic forces that arise from the equilibrium free energy. Phase\ncoexistence is described by bulk state functions and agrees quantitatively with\nBrownian dynamics simulation results from the literature. We describe in detail\nall analytical steps to fully resolve the spatial and orientational dependence\nof the one-body density and current. The decomposition into angular Fourier\nseries leads to coupling of total density, polarization and all higher modes.\nWe describe the power functional approach, including the kinematic dependence\nof the superadiabatic force fields and the quiet life effect that pushes\nparticles from fast to slow regions, and hence induces the phase separation."
    },
    {
        "anchor": "Effective potentials for polymers and colloids: Beyond the van der Waals\n  picture of fluids?: This contribution briefly reviews some recent work demonstrating the partial\nbreakdown of the colloidal fluid <--> atomic fluid analogy. The success of\nliquid state theory for atomic fluids stems in part from the van der Waals\npicture, where steric interactions dominate the structure, and attractive\ninteractions can be added as a perturbation. For complex fluids described by\neffective potentials, this picture may break down. In the first example\ndiscussed, depletion potentials in non-additive hard-sphere mixtures are shown\nto be surprisingly complex, leading to fluid structure and fluid-solid\ntransitions dominated by properties of the attractive potentials instead of by\nthe hard-cores. Many colloidal suspensions, and possibly globular proteins,\nfall into this {\\em energetic fluid} category. In the second example, the\ncoarse-graining of polymers leads to soft-core effective potentials and\nassociated {\\em mean field fluid} behaviour distinguished by a breakdown of the\nvirial expansion, an equation of state that is nevertheless nearly linear in\ndensity, and correlation functions well described by the random phase\napproximation.",
        "positive": "Unsteady wetting of soft solids: From hydrogels and plastics to liquid crystals, soft solids cover a wide\narray of synthetic and biological materials that play key enabling roles in\nadvanced technologies such as 3D printing, soft robotics, wearable electronics,\nself-assembly, and bioartificial tissues. Their elasticity and stimuli-induced\nchanges in mechanical, optical, or electrical properties offer a unique\nadvantage in designing and creating new dynamically functional components for\nsensing, micro-actuation, colour changes, information, and mass transport. To\nharness the vast potential of soft solids, a thorough understanding of their\nreactions when exposed to liquids is needed. Attempts to study the interactions\nbetween soft solids and liquids have largely focused on the wetting of soft\nsolids and its resulting deformation at equilibrium or in a quasi-static state.\nHere, we consider the frequently encountered case of unsteady wetting of a\nliquid on a soft solid and show that transient deformation of the solid is\nnecessary to understand unsteady wetting behaviours. We find that the initial\nspreading of the liquid occurs uninterrupted in the absence of solid\ndeformation. This is followed by intermittent spreading, in which transient\ndeformation of the solid at the three-phase contact line (CL) causes the CL\nmotion to alternate alternation between CL sticking and slipping. We identify\nthe spreading rate of liquids and the viscoelastic reacting rate of soft solids\nas the two competing factors in dictating intermittent spreading. We formulate\nand validate experimentally the conditions required for the contact line to\ntransition from sticking to slipping. By considering the growing deformation of\nsoft solids as dynamic surface heterogeneities, our proposed conditions for\nstick-slip transition in unsteady wetting on soft solids broaden the classical\ntheory on wetting hysteresis on rigid solids."
    },
    {
        "anchor": "Evolution of polygonal crack patterns in mud when subjected to repeated\n  wetting-drying cycles: The present paper demonstrates how a natural crack mosaic resembling a random\ntessellation evolves with repeated 'wetting followed by drying' cycles. The\nnatural system here is a crack network in a drying colloidal material, for\nexample, a layer of mud. A spring network model is used to simulate consecutive\nwetting and drying cycles in mud layers until the crack mosaic matures. The\nsimulated results compare favourably with reported experimental findings. The\nevolution of these crack mosaics has been mapped as a trajectory of a 4-vector\ntuple in a geometry-topology domain. A phenomenological relation between energy\nand crack geometry as functions of time cycles is proposed based on principles\nof crack mechanics. We follow the crack pattern evolution to find that the\npattern veers towards a Voronoi mosaic in order to minimize the system energy.\nSome examples of static crack mosaics in nature have also been explored to\nverify if nature prefers Voronoi patterns. In this context, the authors define\nnew geometric measures of Voronoi-ness of crack mosaics to quantify how close a\ntessellation is to a Voronoi tessellation, or even, to a Centroidal Voronoi\ntessellation.",
        "positive": "Variational Umbrella Seeding for Calculating Nucleation Barriers: In this work, we introduce Variational Umbrella Seeding, a novel technique\nfor computing nucleation barriers. This new method, a refinement of the\noriginal seeding approach, is independent on the choice of order parameter for\nmeasuring the size of a nucleus. Consequently, it surpasses seeding in\naccuracy, and Umbrella Sampling in computational speed. We test the method\nextensively and demonstrate excellent accuracy for crystal nucleation of nearly\nhard spheres and of two distinct models of water: mW and TIP4P/ICE. This method\ncan easily be extended to calculate nucleation barriers for homogeneous\nmelting, condensation, and cavitation."
    },
    {
        "anchor": "Structural and mechanical characteristics of sphere packings near the\n  jamming transition: From fully amorphous to quasi-ordered structures: Mechanically stable sphere packings are generated in three-dimensional space\nusing the discrete element method, which span a wide range in structural order,\nranging from fully amorphous to quasi-ordered structures, as characterized by\nthe bond orientational order parameter. As the packing pressure, $p$, varies\nfrom the marginally rigid limit at the jamming transition ($p \\approx 0$) to\nthat of more robust systems ($p \\gg 0$), the coordination number, $z$, follows\na familiar scaling relation with pressure, namely, $\\Delta z = z - z_c \\sim\np^{1/2}$, where $z_c = 2d = 6$ ($d=3$ is the spatial dimension). While it has\npreviously been noted that $\\Delta z$ does indeed remain the control parameter\nfor determining the packing properties, here we show how the packing structure\nplays an influential role on the mechanical properties of the packings.\nSpecifically, we find that the elastic (bulk $K$ and shear $G$) moduli,\ngenerically referred to as $M$, become functions of both $\\Delta z$ and the\nstructure, to the extent that $M-M_c \\sim \\Delta z$. Here, $M_c$ are values of\nthe elastic moduli at the jamming transition, which depend on the structure of\nthe packings. In particular, the zero shear modulus, $G_c=0$, is a special\nfeature of fully amorphous packings, whereas more ordered packings take larger,\npositive values, $G_c > 0$.",
        "positive": "Surface charge deposition by moving drops reduces contact angles: Slide electrification - the spontaneous charge separation by sliding water\ndrops - can lead to an electrostatic potential of 1 kV and change drop motion\nsubstantially. To find out, how slide electrification influences the contact\nangles of moving drops, we analyzed the dynamic contact angles of aqueous drops\nsliding down tilted plates with insulated surfaces, grounded surfaces, and\nwhile grounding the drop. The observed decrease in dynamic contact angles at\ndifferent salt concentrations is attributed to two effects: An electrocapillary\nreduction of contact angles caused by drop charging and a change in the free\nsurface energy of the solid due to surface charging."
    },
    {
        "anchor": "Microrheology of semiflexible filament solutions based on relaxation\n  simulations: We present an efficient computational methodology to obtain the viscoelastic\nresponse of dilute solutions of semiflexible filaments. By considering an\napproach based on the fluctuation-dissipation theorem, we were able to evaluate\nthe dynamical properties of probe particles immersed in solutions of\nsemiflexible filaments from relaxation simulations with a relatively low\ncomputational cost and higher precision in comparison to those based on\nstochastic dynamics. We used a microrheological approach to obtain the complex\nshear modulus and the complex viscosity of the solution through its compliance\nwhich was obtained directly from the dynamical properties of a probe particle\nattached to an effective medium described by a mesoscopic model, i.e., an\neffective filament model (EFM). The relaxation simulations were applied to\nassess the effects of the bending energy on the viscoelasticity of semiflexible\nfilament solutions and our methodology was validated by comparing the numerical\nresults to experimental data on DNA and collagen solutions.",
        "positive": "Critical temperature for first-order phase transitions in confined\n  systems: We consider the Euclidean $D$-dimensional $-\\lambda |\\phi |^4+\\eta |\\phi |^6$\n($\\lambda ,\\eta >0 $) model with $d$ ($d\\leq D$) compactified dimensions.\nIntroducing temperature by means of the Ginzburg--Landau prescription in the\nmass term of the Hamiltonian, this model can be interpreted as describing a\nfirst-order phase transition for a system in a region of the $D$-dimensional\nspace, limited by $d$ pairs of parallel planes, orthogonal to the coordinates\naxis $x_1, x_2, ..., x_d$. The planes in each pair are separated by distances\n$L_1, L_2, ..., L_d$. We obtain an expression for the transition temperature as\na function of the size of the system, $% T_c(\\{L_i\\})$, $i=1, 2, ..., d$. For\nD=3 we particularize this formula, taking $L_1=L_2=... =L_d=L$ for the\nphysically interesting cases $d=1$ (a film), $d=2$ (an infinitely long wire\nhaving a square cross-section), and for $d=3$ (a cube). For completeness, the\ncorresponding formulas for second-order transitions are also presented.\nComparison with experimental data for superconducting films and wires shows\nqualitative agreement with our theoretical expressions"
    },
    {
        "anchor": "Nematic braids: topological invariants and rewiring of disclinations: The conventional topological description given by the fundamental group of\nnematic order parameter does not adequately explain the entangled defect line\nstructures that have been observed in nematic colloids. We introduce a new\ntopological invariant, the self-linking number, that enables a complete\nclassification of entangled defect line structures in general nematics, even\nwithout particles, and demonstrate our formalism using colloidal dimers, for\nwhich entangled structures have been previously observed. We also unveil a\nsimple rewiring scheme for the orthogonal crossing of two -1/2 disclinations,\nbased on a tetrahedral rotation of two relevant disclination segments, that\nallows us to predict possible nematic braids and calculate their self-linking\nnumbers.",
        "positive": "Dynamic heterogeneity at the experimental glass transition predicted by\n  transferable machine learning: We develop a transferable machine learning model which predicts structural\nrelaxation from amorphous supercooled liquid structures. The trained networks\nare able to predict dynamic heterogeneity across a broad range of temperatures\nand time scales with excellent accuracy and transferability. We use the network\ntransferability to predict dynamic heterogeneity down to the experimental glass\ntransition temperature, $T_g$, where structural relaxation cannot be analyzed\nusing molecular dynamics simulations. The results indicate that the strength,\nthe geometry and the characteristic length scale of the dynamic heterogeneity\nevolve much more slowly near $T_g$ compared to their evolution at higher\ntemperatures. Our results show that machine learning techniques can provide\nphysical insights on the nature of the glass transition that cannot be gained\nusing conventional simulation techniques."
    },
    {
        "anchor": "Buckling, Crumpling, and Tumbling of Semiflexible Sheets in Simple Shear\n  Flow: As 2D materials such as graphene, transition metal dichalcogenides, and 2D\npolymers become more prevalent, solution processing and colloidal-state\nproperties are being exploited to create advanced and functional materials.\nHowever, our understanding of the fundamental behavior of 2D sheets and\nmembranes in fluid flow is still lacking. In this work, we perform numerical\nsimulations of athermal semiflexible sheets with hydrodynamic interactions in\nshear flow. For sheets initially oriented in the flow-gradient plane, we find\nbuckling instabilities of different mode numbers that vary with bending\nstiffness and can be understood with a quasi-static model of elasticity. For\ndifferent initial orientations, chaotic tumbling trajectories are observed.\nNotably, we find that sheets fold or crumple before tumbling but do not stretch\nagain upon applying greater shear.",
        "positive": "Spatial and Temporal fluctuation of an ABP in an optical trap: A colloidal suspension of active Brownian particles (ABPs) driven by\ncontrollable forces into directed or persistent motions can serve as a model\nfor understanding the biological systems. Experiments and numerical simulations\nare established to investigate the motions of an ABP, a single, induced-charge\nelectrophoretic (ICEP) metallic Janus particle, confined in a quadratic\npotential well. On the one hand, 1-D position histograms of the trapped active\nparticle, behaving differently from that of a Boltzmann distribution, reveal a\nsplitting from a single peak of the ABP positional distribution to a bimodal\ndistribution. Decoupling the thermal and non-thermal contributions from the\noverall histogram is non-trivial. However, the two contributions can be\nexamined by convoluting numerically generated thermal and non-thermal\ncontributions into a full histogram. On the other hand, temporal fluctuations\nanalyzed by the power spectral density (PSD), reveal two unique frequencies\ncharacterizing the stiffness of the trap and the rotational diffusion of the\nparticle, respectively. Connections between the spatial and temporal\nfluctuations are obtained by the separate analysis of the temporal and spatial\nfluctuations of an ABP trapped in a quadratic potential well. This study\nreveals how thermal and nonthermal fluctuations play against each other in a\nconfined environment."
    },
    {
        "anchor": "Columnar structures of soft spheres: Metastability and hysteresis: Previously we reported on the stable (i.e. minimal enthalpy) structures of\nsoft monodisperse spheres in a long cylindrical channel. Here, we present\nfurther simulations, which significantly extend the original phase diagram up\nto D/d = 2.714 (ratio of cylinder and sphere diameters), where the nature of\ndensest sphere packing changes. However, macroscopic systems of this kind are\nnot confined to the ideal equilibrium states of this diagram. Consequently, we\nexplore some of the structural transitions to be expected as experimental\nconditions are varied; these are in general hysteretic. We represent these\ntransitions in a stability diagram for a representative case. Illustrative\nvideos are included in the supplemental material.",
        "positive": "From local to hydrodynamic friction in Brownian motion: A multiparticle\n  collision dynamics simulation study: The friction and diffusion coefficients of rigid spherical colloidal\nparticles dissolved in a fluid are determined from velocity and force\nautocorrelation functions by mesoscale hydrodynamic simulations. Colloids with\nboth slip and no-slip boundary conditions are considered, which are embedded in\nfluids modelled by multiparticle collision dynamics (MPC) with and without\nangular momentum conservation. For no-slip boundary conditions, hydrodynamics\nyields the well-known Stokes law, while for slip boundary conditions the lack\nof angular momentum conservation leads to a reduction of the hydrodynamic\nfriction coefficient compared to the classical result. The colloid diffusion\ncoefficient is determined by integration of the velocity autocorrelation\nfunction, where the numerical result at shorter times is combined with the\ntheoretical hydrodynamic expression for longer times. The suitability of this\napproach is confirmed by simulations of sedimenting colloids. In general, we\nfind only minor deviations from the Stokes-Einstein relation, which even\ndisappear for larger colloids. Importantly, for colloids with slip boundary\nconditions, our simulation results contradict the frequently assumed additivity\nof local and hydrodynamic diffusion coefficients."
    },
    {
        "anchor": "Shape-morphing architected sheets with non-periodic cut patterns: We investigate the out-of-plane shape morphing capability of single-material\nelastic sheets with architected cut patterns that result in arrays of tiles\nconnected by flexible hinges. We demonstrate that a non-periodic cut pattern\ncan cause a sheet to buckle into three-dimensional shapes, such as domes or\npatterns of wrinkles, when pulled at specific boundary points. These global\nbuckling modes are observed in experiments and rationalized by an in-plane\nkinematic analysis that highlights the role of the geometric frustration\narising from non-periodicity. The study focuses on elastic sheets, and is later\nextended to elastic-plastic materials to achieve shape retention. Our work\nillustrates a scalable route towards the fabrication of three-dimensional\nobjects with nonzero Gaussian curvature from initially-flat sheets.",
        "positive": "A minimal model of solitons in nematic liquid crystals: Solitons in liquid crystals have generated considerable interest. Several\nhypotheses of varying complexity have been advanced to explain how they emerge,\nand a consensus has not emerged yet about the underlying forces responsible for\ntheir formation or their structure. In this work, we present a minimal model\nfor soliton structures in achiral nematic liquid crystals, which reveals the\nkey requirements needed to generate traveling solitons in the absence of added\ncharges. These include a surface imperfection or inhomogeneity capable of\nproducing a twist, flexoelectricity, dielectric contrast, and an applied AC\nelectric field that can couple to the director's orientation. Our proposed\nmodel is based on a tensorial representation of a confined liquid crystal, and\nit predicts the formation of \"butterfly\" structures, quadrupolar in character,\nin regions of a slit channel where the director is twisted by the surface\nimperfection. As the applied electric field is increased, solitons (or\n\"bullets\") become detached from the wings of the butterfly, which then rapidly\npropagate throughout the system. The main observations that emerge from the\nmodel, including the formation and structure of butterflies, bullets, and\nstripes, as well as the role of surface imperfections and the strength of the\napplied field, are consistent with our own experimental findings presented here\nfor nematic LCs confined between two chemically treated parallel plates."
    },
    {
        "anchor": "Theoretical assessment of the disparity in the electrostatic forces\n  between two point charges and two conductive spheres of equal radii: The Coulomb's formula for the force FC of electrostatic interaction between\ntwo point charges is well known. In reality, however, interactions occur not\nbetween point charges, but between charged bodies of certain geometric form,\nsize and physical structure. This leads to deviation of the estimated force FC\nfrom the real force F of electrostatic interaction, thus imposing the task to\nevaluate the disparity. In the present paper the problem is being solved\ntheoretically for two charged conductive spheres of equal radii and arbitrary\nelectric charges. Assessment of the deviation is given as a function of the\nratio of the distance R between the spheres centers to the sum of their radii.\nFor the purpose, relations between FC and F derived in a preceding work of\nours, are employed to generalize the Coulomb's interactions. At relatively\nshort distances between the spheres, the Coulomb force FC, as estimated to be\ninduced by charges situated at the centers of the spheres, differ significantly\nfrom the real force F of interaction between the spheres. In the case of zero\nand non-zero charge we prove that with increasing the distance between the two\nspheres, the force F decrease rapidly, virtually to zero values, i.e. it\nappears to be short-acting force.",
        "positive": "Transition from granular to Brownian suspension : an inclined plane\n  experiment: We experimentally revisite the flow down an inclined plane of dense granular\nsuspensions, with particles of sizes in the micron range, for which thermal\nfluctuations cannot be ignored. Using confocal microscopy on a miniaturized\nset-up, we observe that, in contrast with standard granular rheology, the flow\nprofiles strongly depend on the particles size. Also, suspensions composed of\nsmall enough particles flow at infinitesimal inclinations. From the velocity\nmeasurements, an effective rheology is extracted in terms of a friction\ncoefficient as a fonction of the dimensionless shear rate (the viscous number),\nand of the particle pressure normalized by the thermal pressure. Inspired by a\nprevious work [1], a phenomenological model based on the sum of a thermal\ncontribution describing the glass transition and an athermal contribution\ncapturing the jamming transition is developed, which reproduces well the\nexperimental observations. The model predicts the existence of a glassy\nfriction angle lower than the granular athermal friction angle, a signature of\nthe glass transition in the framework of a pressure imposed rheology."
    },
    {
        "anchor": "Fluctuating hydrodynamics for dilute granular gases: a Monte Carlo study: We investigate hydrodynamic noise in a dilute granular gas during the\nhomogeneous cooling state, by means of a proper application of the Direct\nSimulation Monte Carlo (DSMC) algorithm. The DSMC includes a source of\nrandomization which is not present in Molecular Dynamics (MD) for inelastic\nhard disks. Notwithstanding this difference, a fair quantitative agreement is\nfound, including a violation of the fluctuation-dissipation relation for the\nnoise amplitude of the same order observed in MD. This study suggests that\ndeterministic collision dynamics is not an essential ingredient to reproduce,\nup to a good degree of approximation, hydrodynamic fluctuations in dilute\ngranular gases.",
        "positive": "The buckling of a swollen thin gel layer bound to a compliant substrate: Gels are used to design bilayered structures with high residual stresses. The\nswelling of a thin layer on a compliant substrate leads to compressive\nstresses. The post-buckling of this layer is investigated experimentally; the\nwavelengths and amplitudes of the resulting modes are measured. A simplified\nmodel with a self-avoiding rod on a Winkler foundation is in semi-quantitative\nagreement with experiments and reproduces the observed cusp-like folds."
    },
    {
        "anchor": "Entropically Driven Helix Formation: The helix is a ubiquitous motif for biopolymers. We propose a heuristic,\nentropically based model that predicts helix formation in a system of hard\nspheres and semiflexible tubes. We find that the entropy of the spheres is\nmaximized when short stretches of the tube form a helix with a geometry close\nto that found in natural helices. Our model could be directly tested with\nwormlike micelles as the tubes, and the effect could be used to self-assemble\nsupramolecular helices.",
        "positive": "Molecular streaming and its voltage control in \u00e5ngstr\u00f6m scale\n  channels: The field of nanofluidics has shown considerable progress over the past\ndecade thanks to key instrumental advances, leading to the discovery of a\nnumber of exotic transport phenomena for fluids and ions under extreme\nconfinement. Recently, van der Waals assembly of 2D materials allowed\nfabrication of artificial channels with angstr\\\"om-scale precision. This\nultimate confinement to the true molecular scale revealed unforeseen behaviour\nfor both mass and ionic transport. In this work, we explore pressure-driven\nstreaming in such molecular-size slits and report a new electro-hydrodynamic\neffect under coupled pressure and electric force. It takes the form of a\ntransistor-like response of the pressure induced ionic streaming: an applied\nbias of a fraction of a volt results in an enhancement of the streaming\nmobility by up to 20 times. The gating effect is observed with both graphite\nand boron nitride channels but exhibits marked material-dependent features. Our\nobservations are rationalized by a theoretical framework for the flow dynamics,\nincluding the frictional interaction of water, ions and the confining surfaces\nas a key ingredient. The material dependence of the voltage modulation can be\ntraced back to a contrasting molecular friction on graphene and boron nitride.\nThe highly nonlinear transport under molecular-scale confinement offers new\nroutes to actively control molecular and ion transport and design elementary\nbuilding blocks for artificial ionic machinery, such as ion pumps. Furthermore,\nit provides a versatile platform to explore electro-mechanical couplings\npotentially at play in recently discovered mechanosensitive ionic channels."
    },
    {
        "anchor": "Magnetic Properties of the Heusler Ru$_2$Mn$_X$ ($X$ = Nb, Ta or V)\n  Compounds: Monte Carlo Simulations: In this paper, we have focused on a comparison of the different magnetic\nproperties of the three nano-Heusler Ru$_2$Mn$_X$ (X = Nb, Ta or V) compounds\nusing the Blume-Capel Ising model. The Heusler structures are composed by\ndifferent mixed spins. In fact, the Ru and Mn atoms are modeled by spin-5/2 and\nspin-1/2, respectively. While, the X atoms ($X$ = Nb, Ta and V) are represented\nby the spin-7/2, spin-3/2 and spin-5/2, respectively. This study is carried out\nby using the Monte Carlo simulations under the Metropolis algorithm. The\nmagnetic behaviors of the three nano-Heusler compounds have been studied and\ndiscussed. It is found that Ferrimagnetic to superparamagnetic transitions were\nobserved corresponding to different blocking temperatures. Besides, the effect\nof the crystal field, the exchange coupling interactions and the external\nmagnetic field have been inspected on the magnetization of each nano-Heusler\ncompound Ru$_2$Mn$_X$ ($X$ = Nb, Ta or V).",
        "positive": "Local thermal energy as a structural indicator in glasses: Identifying heterogeneous structures in glasses --- such as localized soft\nspots --- and understanding structure-dynamics relations in these systems\nremain major scientific challenges. Here we derive an exact expression for the\nlocal thermal energy of interacting particles (the mean local potential energy\nchange due to thermal fluctuations) in glassy systems by a systematic\nlow-temperature expansion. We show that the local thermal energy can attain\nanomalously large values, inversely related to the degree of softness of\nlocalized structures in a glass, determined by a coupling between internal\nstresses --- an intrinsic signature of glassy frustration ---, anharmonicity\nand low-frequency vibrational modes. These anomalously large values follow a\nfat-tailed distribution, with a universal exponent related to the recently\nobserved universal $\\omega^4$ density of states of quasi-localized\nlow-frequency vibrational modes. When the spatial thermal energy field --- a\n`softness field' --- is considered, this power-law tail manifests itself by\nhighly localized spots which are significantly softer than their surroundings.\nThese soft spots are shown to be susceptible to plastic rearrangements under\nexternal driving forces, having predictive powers that surpass those of the\nnormal-modes-based approach. These results offer a general,\nsystem/model-independent, physical-observable-based approach to identify\nstructural properties of quiescent glasses and to relate them to glassy\ndynamics."
    },
    {
        "anchor": "Hamilton's equations for a fluid membrane: axial symmetry: Consider a homogenous fluid membrane, or vesicle, described by the\nHelfrich-Canham energy, quadratic in the mean curvature. When the membrane is\naxially symmetric, this energy can be viewed as an `action' describing the\nmotion of a particle; the contours of equilibrium geometries are identified\nwith particle trajectories. A novel Hamiltonian formulation of the problem is\npresented which exhibits the following two features: {\\it (i)} the second\nderivatives appearing in the action through the mean curvature are accommodated\nin a natural phase space; {\\it (ii)} the intrinsic freedom associated with the\nchoice of evolution parameter along the contour is preserved. As a result, the\nphase space involves momenta conjugate not only to the particle position but\nalso to its velocity, and there are constraints on the phase space variables.\nThis formulation provides the groundwork for a field theoretical generalization\nto arbitrary configurations, with the particle replaced by a loop in space.",
        "positive": "Ferroelectric thin films phase diagrams with self-polarized phase and\n  electret state: In present work we calculated the three components of polarization in\nphenomenological theory framework by consideration of three Euler-Lagrange\nequations, which include mismatch effect and influence of misfit dislocations,\nsurface piezoelectric effect caused by broken symmetry on the film surface,\nsurface tension and depolarization field. These equations were solved with the\nhelp of variational method proposed by us earlier. This approach lead to the\nfree energy in the form of algebraic equation of different powers of\npolarization components with the coefficients dependent on film thickness,\nmismatch effect, temperature and other parameters. Several new terms\nproportional to misfit strain appeared in the free energy expression: built-in\nelectric field normal to the surface originated from piezoelectricity in\nvicinity of surface even for the cubic symmetry of bulk ferroelectrics, odd\npowers of normal to the surface component of polarization. The obtained free\nenergy made it possible to calculate all properties of the film by conventional\nprocedure of minimization. As an example we calculated phase diagrams of PZT\n50/50 films on different substrates that lead to compressive or tensile strain.\nThe calculations of pyroelectric coefficient and dielectric permittivity\ntemperature dependencies had shown the electret-like polar state, e.g.\nexistence of pyroelectricity, below the critical thickness of\nferroelectric-paraelectric phase transitions. Our theory predicts, that\nmismatch-induced field could be compatible with thermodynamic coercive field\nand thus cause self-polarization in thin ferroelectric films."
    },
    {
        "anchor": "Nonlinear rheology of colloidal dispersions: Colloidal dispersions are commonly encountered in everyday life and represent\nan important class of complex fluid. Of particular significance for many\ncommercial products and industrial processes is the ability to control and\nmanipulate the macroscopic flow response of a dispersion by tuning the\nmicroscopic interactions between the constituents. An important step towards\nattaining this goal is the development of robust theoretical methods for\npredicting from first-principles the rheology and nonequilibrium microstructure\nof well defined model systems subject to external flow. In this review we give\nan overview of some promising theoretical approaches and the phenomena they\nseek to describe, focusing, for simplicity, on systems for which the colloidal\nparticles interact via strongly repulsive, spherically symmetric interactions.\nIn presenting the various theories, we will consider first low volume fraction\nsystems, for which a number of exact results may be derived, before moving on\nto consider the intermediate and high volume fraction states which present both\nthe most interesting physics and the most demanding technical challenges. In\nthe high volume fraction regime particular emphasis will be given to the\nrheology of dynamically arrested states.",
        "positive": "Surface tensions and surface potentials of acid solutions: A theory is presented which allows us to quantitatively calculate the excess\nsurface tension of acid solutions. The H^+, in the form of hydronium ion, is\nfound to be strongly adsorbed to the solution-air interface. To account for the\nelectrostatic potential difference measured experimentally, it is necessary to\nassume that the hydronium ion is oriented with its hydrogens pointing into the\nbulk water. The theory is quantitatively accurate for surface tensions and is\nqualitative for electrostatic potential difference across the air-water\ninterface."
    },
    {
        "anchor": "Equilibrium sedimentation profiles of charged colloidal suspensions: We investigate the sedimentation equilibrium of a charge stabilized colloidal\nsuspension in the regime of low ionic strength. We analyze the asymptotic\nbehaviour of the density profiles on the basis of a simple Poisson--Boltzmann\ntheory and show that the effective mass we can deduce from the barometric law\ncorresponds to the actual mass of the colloidal particles, contrary to previous\nstudies.",
        "positive": "Different scenarios of dynamic coupling in glassy colloidal mixtures: Colloidal mixtures represent a versatile model system to study transport in\ncomplex environments. They allow for a systematic variation of the control\nparameters, namely size ratio, total volume fraction and composition. We study\nthe effects of these parameters on the dynamics of dense suspensions using\nmolecular dynamics simulations and differential dynamic microscopy experiments.\nWe investigate the motion of the small particles through the matrix of large\nparticles as well as the motion of the large particles. A particular focus is\non the coupling of the collective dynamics of the small and large particles and\non the different mechanisms leading to this coupling. For large size ratios,\nabout 1:5, and an increasing fraction of small particles, the dynamics of the\ntwo species become increasingly coupled and reflect the structure of the large\nparticles. This is attributed to the dominant effect of the large particles on\nthe motion of the small particles which is mediated by the increasing crowding\nof the small particles. Furthermore, for moderate size ratios, about 1:3, and\nsufficiently high fractions of small particles, mixed cages are formed and\nhence the dynamics are also strongly coupled. Again, the coupling becomes\nweaker as the fraction of small particles is decreased. In this case, however,\nthe collective intermediate scattering function of the small particles shows a\nlogarithmic decay corresponding to a broad range of relaxation times."
    },
    {
        "anchor": "Self-Assembly, Interfacial Properties, Interactions with Macromolecules\n  and Molecular Modelling and Simulation of Microbial Bio-based Amphiphiles\n  (Biosurfactants). A Tutorial Review: Chemical surfactants are omnipresent in consumers' products but they suffer\nfrom environmental concerns. For this reason, complete replacement of\npetrochemical surfactants by biosurfactants constitute a holy grail but this is\nfar from occurring any soon. If the \"biosurfactants revolution\" has not\noccurred, yet, mainly due to the higher cost and lower availability of\nbiosurfactants, another reason explains this fact: the poor knowledge of their\nproperties in solution. This tutorial review aims at reviewing the\nself-assembly properties and phase behavior, experimental (sections 2.3 and\n2.4) and from molecular modelling (section 5), in water of the most important\nmicrobial biosurfactants (sophorolipids, rhamnolipids, surfacting,\ncellobioselipids, glucolipids) as well as their major derivatives. A critical\ndiscussion of such properties in light of the well-known packing parameter of\nsurfactants is also provided (section 2.5). The relationship between the\nnanoscale self-assembly and macroscopic materials properties, including\nhydrogelling, solid foaming, templating or encapsulation is specifically\ndiscussed (section 2.7). We also present their self-assembly and adsorption at\nflat and complex air/liquid (e.g., foams), air/solid (adhesion), liquid/solid\n(nanoparticles) and liquid/liquid (e.g., emulsions) interfaces (section 3). A\ncritical discussion on the use of biosurfactants as capping agents for the\ndevelopment of stable nanoparticles is specifically provided (section 3.2.4).\nFinally, we discuss the major findings involving biosurfactants and\nmacromolecules, including proteins, enzymes, polymers and polyelectrolytes.",
        "positive": "Particle Conservation in Dynamical Density Functional Theory: We present the exact adiabatic theory for the dynamics of the inhomogeneous\ndensity distribution of a classical fluid. Erroneous particle number\nfluctuations of dynamical density functional theory are absent, both for\ncanonical and grand canonical initial conditions. We obtain the canonical free\nenergy functional, which yields the adiabatic interparticle forces of\noverdamped Brownian motion. Using an exact and one of the most advanced\napproximate hard core free energy functionals, we obtain excellent agreement\nwith simulations. The theory applies to finite systems in and out of\nequilibrium."
    },
    {
        "anchor": "Probabilistic Description of Traffic Breakdowns Caused by On-ramp Flow: The characteristic features of traffic breakdown near on-ramp are analyzed.\nTo describe this phenomenon the probabilistic description regarding the jam\nemergence as the formation of a large car cluster on highway inside the\nsynchronized traffic is constructed. In these terms the breakdown occurs\nthrough the formation of a certain critical nucleus in the metastable vehicle\nflow, which is located near the on-ramp. The strong cooperative car interaction\nin the synchronized traffic enables us to treat the size of critical jam nuclei\nas a large value and to apply to an effective one-lane model. This model\nassumes the following. First, the growth of a car cluster is governed by the\nattachment of cars to the cluster whose rate is mainly specified by the total\ntraffic flow. Second, the cluster dissolution is determined by the car escape\nfrom the cluster whose rate depends on the cluster size directly. Third, the\ngeneration of one-car clusters (preclusters) is caused by cars entering the\nmain road from the on-ramp. The appropriate master equation for the car cluster\nevolution is written and the generation rate of critical jam nuclei is found.\nThe obtained results are in agreement with the empirical facts that the\ncharacteristic time scale of the breakdown phenomenon is about or greater than\none minute and the traffic flow rate interval inside which traffic breakdowns\nare observed is sufficiently wide. Besides, as a new results, it is shown that\nthe traffic breakdown probability can be analyzed, at least approximately,\nbased solely on the data of the total vehicle flow without separating it into\nthe vehicle streams on the main road and on-ramp when the relative on-ramp flow\nvolume exceeds 10%--20%.",
        "positive": "Free energy approximations in simple lattice proteins: This work addresses the question of whether it is possible to define simple\npair-wise interaction terms to approximate free energies of proteins or\npolymers. Rather than ask how reliable a potential of mean force is, one can\nask how reliable it could possibly be. In a two-dimensional, infinite lattice\nmodel system one can calculate exact free energies by exhaustive enumeration. A\nseries of approximations were fitted to exact results to assess the feasibility\nand utility of pair-wise free energy terms. Approximating the true free energy\nwith pair-wise interactions gives a poor fit with little transferability\nbetween systems of different size. Adding extra artificial terms to the\napproximation yields better fits, but does not improve the ability to\ngeneralise from one system size to another. Further, one cannot distinguish\nfolding from non-folding sequences via the approximated free energies. Most\nusefully, the methodology shows how one can assess the utility of various terms\nin lattice protein/polymer models."
    },
    {
        "anchor": "Scaling behavior in wave localization: Wave localization is a ubiquitous phenomenon. It refers to situations that\ntransmitted waves in scattering media are trapped in space and remain confined\nin the vicinity of the initial site until dissipated. Based on a scaling\nanalysis, the localization behavior in two and three dimensions is studied. It\nis shown that the localization transition is possible in two dimensional\nsystems, supporting the recent numerical results.",
        "positive": "Pendant Capsule Elastometry: We provide a C/C++ software for the shape analysis of deflated elastic\ncapsules in a pendant capsule geometry, which is based on an elastic\ndescription of the capsule material as a quasi two-dimensional elastic membrane\nusing shell theory. Pendant capsule elastometry provides a new in-situ and\nnon-contact method for interfacial rheology of elastic capsules. Given an\nelastic model of the capsule membrane, pendant capsule elastometry determines\noptimal elastic moduli by fitting numerically generated axisymmetric shapes\noptimally to an experimental image. For each digitized image of a deflated\ncapsule elastic moduli can be determined, if another image of its undeformed\nreference shape is provided. Within this paper, we focus on nonlinear Hookean\nelasticity because of its low computational cost its wide applicability, but\nalso discuss and implement alternative constitutive laws. For Hookean\nelasticity, Young's surface modulus (or, alternatively, area compression\nmodulus) and Poisson's ratio are determined; for Mooney-Rivlin elasticity, the\nRivlin modulus and a dimensionless shape parameter are determined; for\nneo-Hookean elasticity, only the Rivlin modulus is determined, using a fixed\ndimensionless shape parameter. Comparing results for different models we find\nthat nonlinear Hookean elasticity is adequate for most capsules. If series of\nimages are available, these moduli can be evaluated as a function of the\ncapsule volume to analyze hysteresis or aging effects depending on the\ndeformation history. An additional wrinkling wavelength measurement allows the\nuser to determine the bending modulus, from which the layer thickness can be\nderived. We verify the method by analyzing several materials, compare the\nresults to available rheological measurements, and review several applications.\nWe make the software available under the GPL license at\ngithub.com/jhegemann/opencapsule."
    },
    {
        "anchor": "Dynamic patterning and texture evolution of microbubbles in\n  non-Newtonian immobile droplet: The dynamical perspectives of bubble in a liquid droplet on smooth solid\nsubstrate can be revealed by investigating interfacial self-assembly phenomena.\nMoreover, the complexity in such system can be scaled down into a transparent\nimmobile non-Newtonian droplet. Here we present the dynamical approaches of\ninternal microbubbles through coalescence and implosion near the edge of the\ndroplet. The aggregation density of microbubbles near the rim is greater than\nthe central region corresponding to the dynamical behaviour of the droplet\nmarked with capillary flow along the triple phase contact line. We have also\nnumerically analysed the occurrence of aggregation density of internal\nmicrobubbles near the edge by implementing boundary integral method. Our\nnumerical results show good agreement with the experimental findings until the\naggregation density have occurred near the edge of the droplet. This\nunderstanding ascribes distinctive skew exponential power law characteristics\nthrough coalescence and implosion.",
        "positive": "Large scale molecular dynamics simulation of self-assembly processes in\n  short and long chain cationic surfactants: We report on an investigation of the structural and dynamical properties of\nn-nonyltrimethylammonium chloride (C9TAC) and erucyl bis [2-hydroxyethyl]\nmethylammonium chloride (EMAC) micelles in aqueous solution. A fully atomistic\ndescription was used, and the time evolution was computed using molecular\ndynamics."
    },
    {
        "anchor": "Straightening wrinkles: We consider the elastic deformation of a circular cylindrical sector composed\nof an incompressible isotropic soft solid when it is straightened into a\nrectangular block. In this process, the circumferential line elements on the\noriginal inner face of the sector are stretched while those on the original\nouter face are contracted. We investigate the geometrical and physical\nconditions under which the latter line elements can be contracted to the point\nwhere a localized incremental instability develops. We provide a robust\nalgorithm to solve the corresponding two-point boundary value problem, which is\nstiff numerically. We illustrate the results with full incremental displacement\nfields in the case of Mooney-Rivlin materials and also perform an asymptotic\nanalysis for thin sectors",
        "positive": "Coincident Molecular Auxeticity and Negative Order Parameter in a Liquid\n  Crystal Elastomer: \"Auxetic\" materials have the counter-intuitive property of expanding rather\nthan contracting perpendicular to an applied stretch, formally they have\nnegative Poisson's Ratios (PRs).[1,2] This results in properties such as\nenhanced energy absorption and indentation resistance, which means that\nauxetics have potential for applications in areas from aerospace to biomedical\nindustries.[3,4] Existing synthetic auxetics are all created by carefully\nstructuring porous geometries from positive PR materials. Crucially, their\ngeometry causes the auxeticity.[3,4] The necessary porosity weakens the\nmaterial compared to the bulk and the structure must be engineered, for\nexample, by using resource-intensive additive manufacturing processes.[1,5] A\nlongstanding goal for researchers has been the development of a synthetic\nmaterial that has intrinsic auxetic behaviour. Such \"molecular auxetics\" would\navoid porosity-weakening and their very existence implies chemical\ntuneability.[1,4-9] However molecular auxeticity has never previously been\nproven for a synthetic material.[6,7] Here we present a synthetic molecular\nauxetic based on a monodomain liquid crystal elastomer (LCE). When stressed\nperpendicular to the alignment direction, the LCE becomes auxetic at strains\ngreater than approximately 0.8 with a minimum PR of -0.8. The critical strain\nfor auxeticity coincides with the occurrence of a negative liquid crystal order\nparameter (LCOP). We show the auxeticity agrees with theoretical predictions\nderived from the Warner and Terentjev theory of LCEs.[10] This demonstration of\na synthetic molecular auxetic represents the origin of a new approach to\nproducing molecular auxetics with a range of physical properties and functional\nbehaviours. Further, it demonstrates a novel feature of LCEs and a route for\nrealisation of the molecular auxetic technologies that have been proposed over\nthe years."
    },
    {
        "anchor": "Influence of particle size on the thermoresponsive and rheological\n  properties of aqueous poly(N-isopropylacrylamide) colloidal suspensions: Thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) particles of different\nsizes are synthesized by varying the concentration of sodium dodecyl sulphate\n(SDS) in a one-pot method. The sizes, size polydispersities and the\nthermoresponsivity of the PNIPAM particles are characterized by using dynamic\nlight scattering and scanning electron microscopy. It is observed that the\nsizes of these particles decrease with increase in SDS concentration. Swelling\nratios of PNIPAM particles measured from the thermoresponsive curves are\nobserved to increase with decrease in particle size. This observation is\nunderstood by minimizing the Helmholtz free energy of the system with respect\nto the swelling ratio of the particles. Finally, the dynamics of these\nparticles in jammed aqueous suspensions are investigated by performing\nrheological measurements.",
        "positive": "Determination of the entropy production during glass transition: theory\n  and experiment: A glass is a non-equilibrium thermodynamic state whose physical properties\ndepend on time. Glass formation from the melt, as well as the inverse process\nof liquid structural recovery from the glass are non-equilibrium processes. A\npositive amount of entropy is produced during such irreversible processes. In\nthis paper, we address the issue of the determination of entropy production\nduring glass transition. Firstly, we theoretically determine the entropy\nproduction by means of the statistical model of a two-level system coupled to a\nmaster equation driving the time dependency of the occupancy probability of\neach state. Thermodynamic cycles of the type liquid-glass-liquid are considered\nin order to test the validity of the Clausius theorem. Secondly, we determine\nexperimentally the production of entropy from differential scanning calorimetry\nexperiments on the PolyVinylAcetate glass-former. Aging experiments are also\nconsidered. From the data treatments proposed here, we are able to determine\nthe rate of production of entropy in each part of the experiments. Although\nbeing on the order of few % or less of the configurational entropy involved in\nthe glass formation, the positive production of entropy is clearly determined.\nFor all the thermodynamic cycles considered in these calorimetric experiments,\nthe Clausius theorem is fulfilled."
    },
    {
        "anchor": "Viscous friction acting on a solid disk falling in confined fluid:\n  lessons for the scaling analysis: We fill a viscous liquid in a vertically stood cell of millimeter thickness,\ncalled the Hele-Shaw cell, and insert a disk in the liquid whose thickness is\nsmaller than the cell thickness. The disk starts falling in the liquid due to\ngravity opposed by viscous friction. We focus on the case in which lubricating\nfilms formed in the gap between the cell surface and the disk surface are\nthinner than the disk thickness. As a result, we find an apparent scaling\nregime for the falling velocity of a disk, in which the thickness of the\nlubricating film characterizes the dynamics. We further show that the apparent\nscaling regime is explained simply as a result of competition of two scaling\nregimes, elucidating the physics of the viscous friction. The present study is\nthus relevant to fundamental issues and applications in various fields in which\nsmall-scale physics in the flow at low Reynolds numbers is essential, such as\nmicrofluidics, bioconvection, and active matter. The simple scenario for\nexplaining an apparent scaling law demonstrated in the present study would be\nuseful in diverse fields, considering that the generality and strength of\nscaling analysis in science and that simple arguments usually lead to a few\ndifferent scaling laws for a given problem.",
        "positive": "Scaling of Spinodal Turbulence between Viscous and Inertial Hydrodynamic\n  Regimes: The existence of unique scaling in a crossover regime between viscous and\ninertial hydrodynamic regimes is revealed for homogeneous, isotropic,\nincompressible, spinodal turbulence which is characterized, to begin with, by\nthree different length scales and a velocity scale. The obtained scaling\nexponents are found to be in agreement and in consistency with available\nsimulation results for a broad range of crossover regime. Also, it is observed\nthat the spinodal turbulence in the crossover regime is in complete consistency\nwith the universality class of self-preservation of decaying grid turbulence.\nWe then obtain analytical forms for various scalings, valid in the crossover\nregime, through the analysis for self-preservation of spinodal turbulence."
    },
    {
        "anchor": "Simulating dense granular suspension rheology using LAMMPS: Dense suspensions are widespread in nature, manufacturing and process\nengineering. Particle-based simulations have proven to be an invaluable\ncomplement to experimental rheological characterisation, serving as a virtual\nrheometer that enables rapid exploration of parameter space and detailed\nscrutiny of microscopic dynamics. To maximise the utility of such simulations,\nit can be advantageous to exploit pre-existing, well-optimised, well-documented\ncodes. Here we provide a simple description of how to use LAMMPS to study the\nrheology of dense, granular suspensions.",
        "positive": "Are polar liquids less simple?: Strong correlation between equilibrium fluctuations of the potential energy,\nU, and the virial, W, is a characteristic of a liquid that implies the presence\nof certain dynamic properties, such as density scaling of the relaxation times\nand isochronal superpositioning of the relaxation function. In this work we\nemploy molecular dynamics simulations (mds) on methanol and two variations,\nlacking hydrogen bonds and a dipole moment, to assess the connection between\nthe correlation of U and W and these dynamic properties. We show, in accord\nwith prior results of others [T.S. Ingebrigtsen, T.B. Schroder, J.C. Dyre,\nPhys. Rev. X 2, 011011 (2012).], that simple van der Waals liquids exhibit both\nstrong correlations and the expected dynamic behavior. However, for polar\nliquids this correspondence breaks down - weaker correlation between U and W is\nnot associated with worse conformance to density scaling or isochronal\nsuperpositioning. The reason for this is that strong correlation between U and\nW only requires their proportionality, whereas the expected dynamic behavior\ndepends primarily on constancy of the proportionality constant for all state\npoints. For hydrogen-bonded liquids, neither strong correlation nor adherence\nto the dynamic properties is observed; however, this nonconformance is not\ndirectly related to the concentration of hydrogen bonds, but rather to the\ngreater deviation of the intermolecular potential from an inverse power law\n(IPL). Only (hypothetical) liquids having interactions governed strictly by an\nIPL are perfectly correlating and exhibit the consequent dynamic properties\nover all thermodynamic conditions."
    },
    {
        "anchor": "Mean-field electrostatics beyond the point-charge description: This review explores the number of mean-field constructions for ions whose\nstructure goes beyond the point-charge description, a representation used in\nthe standard Poisson-Boltzmann equation. The exploration is motivated by a body\nof experimental work which indicates that ion-specific effects play a\nsignificant role, where ions of the same valence charge but different size,\npolarizability, or shape yield quite different, and sometimes surprising\nresults. Furthermore, there are many large ions encountered in soft-matter and\nbiophysics that do not fit into a point-charge description, and their extension\nin space and shape must be taken into account of any reasonable representation.",
        "positive": "Size and shape dependence of finite volume Kirkwood-Buff integrals: Analytic relations are derived for finite volume integrals over the radial\ndistribution function of a fluid, so-called Kirkwood-Buff integrals. Closed\nform expressions are obtained for cubes and cuboids, the system shapes commonly\nemployed in molecular simulations. When finite volume Kirkwood-Buff integrals\nare expanded over inverse system size, the leading term depends on shape only\nthrough the surface area to volume ratio. This conjecture is proved for\narbitrary shapes and a general expression for the leading term is derived. From\nthis, a new extrapolation to the infinite volume limit is proposed, which\nconverges much faster with system size than previous approximations and thus\nsignificantly simplifies the numerical computations."
    },
    {
        "anchor": "Quantum Kramers turnover: a phase space function approach: The problem of Kramers' turnover is a central issue of dynamical theory of\nreaction rate. Since its classical solution in the Markovian limit in\nmid-eighties by Melnikov and Meshkov, the problem has been addressed by a\nnumber of groups in the last decade both in classical non-Markovian and quantum\nmechanical context. Based on a coherent state representation of noise operators\nand a positive definite Wigner canonical thermal distribution function we have\nrecently developed a c-number quantum Langevin equation [Barik \\textit{et al},\nJ. Chem. Phys. {\\bf 119}, 680 (2003); Banerjee \\textit{et al}, Phys. Rev. E\n{\\bf 65}, 021109 (2002)]. We implement this scheme within Pollak's well known\nnormal mode description to calculate the quantum transmission coefficient over\nan arbitrary range of friction, noise correlation and temperature. The theory\ngeneralizes the quantum correction to Grote-Hynes factor in the rate expression\ndown to vacuum limit which reduces to well known high temperature quantum\ncorrection, \\textit{i.e.}, the Wolynes term for quantum transmission and\nreflection for the barrier in the appropriate limit and also considers the\nquantum corrections due to nonlinearity of the system potential order by order\nwhich contributes to energy loss and dispersion due to coupling between\nunstable and stable normal modes near the barrier top and is valid for both\nabove and below the activated tunneling regime. Our results have been compared\nwith those obtained earlier for a model potential and found to be good\nagreement.",
        "positive": "The crucial role of elasticity in regulating liquid-liquid phase\n  separation in cells: Liquid-liquid phase separation has emerged as a fundamental mechanism\nunderlying intracellular organization, with evidence for it being reported in\nnumerous different systems. However, there is a growing concern regarding the\nlack of quantitative rigor in the techniques employed to study phase\nseparation, and their ability to account for the complex nature of the cellular\nmilieu, which affects key experimentally observable measures, such as the\nshape, size and transport dynamics of liquid droplets. Here we bridge this gap\nby combining recent experimental data with theoretical predictions that capture\nthe subtleties of nonlinear elasticity and fluid transport. We show that within\na biologically accessible range of material parameters, phase separation is\nhighly sensitive to elastic properties and can thus be used as a mechanical\nswitch to rapidly transition between different states in cellular systems.\nFurthermore, we show that this active mechanically mediated mechanism can drive\ntransport across cells at biologically relevant timescales and could play a\ncrucial role in promoting spatial localization of condensates; whether cells\nexploit such mechanisms for transport of their constituents, remains an open\nquestion."
    },
    {
        "anchor": "On the origin of permeative flows in cholesteric liquid crystals: Permeative flows, known for the explanation of the anomalous viscosity (10^5\nPoise) in cholesterics at low shear rates, are still under debate due to the\ndifficulty of experiments. Here we use the Surface Force Balance, in which\nuniform domains with regular circular defects are formed, to probe the forces\ngenerated by compression in the direction of the helical axis. At the\nquasi-static speed of the surface approach, the measured forces are shown to be\nelastic (not dissipative), arising from the twist elastic deformation when the\nplanar anchoring at the walls is strong. A mechanism involving frictional\nsurface torque under strong planar surface anchoring will be proposed. The\nresults indicate that the strong resistance to flow observed, previously\ninterpreted as an enormous apparent viscosity, may in fact originate from the\nintrinsic non-linear increase of elasticity when the molecules are rotated away\nfrom equilibrium. The system is found to store energy (the force is\nreversible), without dissipation, as long as the applied stress is below the\nthreshold for nucleating new defects. Our study underpins the importance of\nboundary conditions that may dramatically change the rheology of other\nviscoelastic materials and sheds light on the rational design of\nstrain-stiffening materials, nanomotors, and artificial muscles involving\nhelical architectures.",
        "positive": "Collective motion of granular matter subjected to swirling excitation: A two-dimensional granular packing under horizontally circular shaking\nexhibits various collective motion modes depending on the strength of the\noscillation and the global packing density. For intermediate packing density\nand oscillation amplitude, a high density phase travels along the container's\nside wall in clockwise direction, while the oscillation itself is\nanti-clockwise. Further increasing packing density towards the hexagonal\npacking, the whole packing rotates collectively in clockwise direction. The\ncore of the packing rotates as a solid and is separated from the boundary by a\nfluid-like layer. Both motion modes are associated with the asymmetric motion\nof particles close to the side wall."
    },
    {
        "anchor": "Nematic cells with defect-patterned alignment layers: Using Monte Carlo simulations of the Lebwohl--Lasher model we study the\ndirector ordering in a nematic cell where the top and bottom surfaces are\npatterned with a lattice of $\\pm 1$ point topological defects of lattice\nspacing $a$. We find that the nematic order depends crucially on the ratio of\nthe height of the cell $H$ to $a$. When $H/a \\gtrsim 0.9$ the system is very\nwell--ordered and the frustration induced by the lattice of defects is relieved\nby a network of half--integer defect lines which emerge from the point defects\nand hug the top and bottom surfaces of the cell. When $H/a \\lesssim 0.9$ the\nsystem is disordered and the half--integer defect lines thread through the cell\njoining point defects on the top and bottom surfaces. We present a simple\nphysical argument in terms of the length of the defect lines to explain these\nresults. To facilitate eventual comparison with experimental systems we also\nsimulate optical textures and study the switching behavior in the presence of\nan electric field.",
        "positive": "Can magnetism-assisted quasiperiodic structures in Russell-FeS `bubbles'\n  offer a quantum coherent origin of life?: This paper seeks to expand the scope of the alkaline seepage site\nhydrothermal mound scenario of Russell et al, by appealing to its wider canvas\nfor hypothesizing self-assembly of gregite clusters via interplay of forces\nwithin the gel phase of FeS membranes: directed heat transport a la\nRayleigh-Benard convection for dissociation, vs oriented attachment (small\nclusters) and magnetic forces (large clusters) for association, the latter\nassisted by magnetic mound constituents. The directed movement of tiny clusters\nthrough cluster layers are reminiscent of processes like budding, molecular\nmotors, pre-RNA world on the lines of Cairns-Smith's hypothesis, and optical\npolarity. Higher rate of (soft) multinucleate formation vs growth rate of\n(rigid) microcrystals, correlates with icosahedral (forbidden\ncrystallographically!) framboidal morphology. This pattern indicates a link to\nphylotaxis, thus reinforcing the quasi-periodicity connection which can provide\na natural access to features like surface limit, anomalous transport and low\nthermal conductivity, while facilitating diffusion through clusters. And\nmagnetism offers a hierarchy of features: primordial multicellularity; phase\ncorrelations of assembled molecules; overcoming thermal decoherence. These\ndynamical nested structures offer possibilities for iterative computations,\nadaptive learning, and coherent quantum searches. The link between enzymatic\nFeS clusters and the Hadean ocean floor is seen as part of a larger conceptual\nframework uncovering a role for Magnetism and the Origin of Life."
    },
    {
        "anchor": "Phase behaviour of fluids in undulated nanopores: The geometry of walls forming a narrow pore may qualitatively affect the\nphase behaviour of the confined fluid. Specifically, the nature of condensation\nin nanopores formed of sinusoidally-shaped walls (with amplitude $A$ and period\n$P$) is governed by the wall mean separation $L$ as follows. For $L>L_t$, where\n$L_t$ increases with $A$, the pores exhibit standard capillary condensation\nsimilar to planar slits. In contrast, for $L<L_t$, the condensation occurs in\ntwo steps, such that the fluid first condenses locally via bridging transition\nconnecting adjacent crests of the walls, before it condenses globally. For the\nmarginal value of $L=L_t$, all the three phases (gas-like, bridge and\nliquid-like) may coexist. We show that the locations of the phase transitions\ncan be described using geometric arguments leading to modified Kelvin\nequations. However, for completely wet walls, to which we focus on, the phase\nboundaries are shifted significantly due to the presence of wetting layers. In\norder to take this into account, mesoscopic corrections to the macroscopic\ntheory are proposed. The resulting predictions are shown to be in a very good\nagreement with a density functional theory even for molecularly narrow pores.\nThe limits of stability of the bridge phase, controlled by the pore geometry,\nis also discussed in some detail.",
        "positive": "Computational study of the cross-link and the entanglement contributions\n  to the elastic properties of model PDMS networks: We built randomly cross-linked model PDMS networks and used Molecular\nDynamics Methods to obtain stress-strain curves. Mooney-Rivlin (MR) analysis\nwas used to estimate the shear moduli. We applied Primitive Path analysis (PPA)\nand its variation, Phantom Primitive Path analysis (3PA), to estimate the\nentanglement and the cross-link moduli, respectively. The MR moduli estimates\nare in good agreement with the sum of the entanglement and the cross-link\nmoduli, and we observe that the stress-strain data collapse to a universal form\nwhen reduced with the PPA and 3PA moduli. We studied how the MR parameters\n$\\mathrm{C}_1$, $\\mathrm{C}_2$ vary from cross-link to entanglement dominated\nnetworks. For the latter, we observed a $40\\%$, $60\\%$ contribution of\n$2\\,\\mathrm{C}_1$, $2\\,\\mathrm{C}_2$ to the shear modulus, respectively.\nFinally, we fitted several models to the data. While all fits are good, the\nestimates for the entanglement and the cross-link moduli vary significantly\nwhen compared to our PPA and 3PA benchmarks."
    },
    {
        "anchor": "Polyelectrolyte gels in poor solvent: Equilibrium and non equilibrium\n  elasticity: We study theoretically using scaling arguments the behavior of\npolyelectrolyte gels in poor solvents. Following the classical picture of\nKatchalsky, our approach is based on single chain elasticity but it accounts\nfor the recently proposed pearl-necklace structure of polyelectrolytes in poor\nsolvents. The elasticity both of gels at swelling equilibrium and of partially\nswollen, non equilibrium, gels is studied when parameters such as the ionic\nstrength or the fraction of charged monomers are varied. Our theory could be\nuseful to interpret recent experiments performed in Strasbourg that show that\nif identical gel samples are swollen to the same extent at different pH the\nsample with the highest charge has the lowest shear modulus.",
        "positive": "Kramers-Kronig Relations for Nonlinear Rheology: 1. General Expression\n  and Implications: The principle of causality leads to linear Kramers-Kronig relations (KKR)\nthat relate the real and imaginary parts of the complex modulus $G^{*}$ through\nintegral transforms. Using the multiple integral generalization of the\nBoltzmann superposition principle for nonlinear rheology, and the principle of\ncausality, we derived nonlinear KKR, which relate the real and imaginary parts\nof the $n^\\text{th}$ order complex modulus $G_{n}^{*}$. For $n$=3, we obtained\nnonlinear KKR for medium amplitude parallel superposition (MAPS) rheology. A\nspecial case of MAPS is medium amplitude oscillatory shear (MAOS); we obtained\nMAOS KKR for the third-harmonic MAOS modulus $G_{33}^{*}$; however, no such KKR\nexists for the first harmonic MAOS modulus $G_{31}^{*}$. We verified MAPS and\nMAOS KKR for the single mode Giesekus model. We also probed the sensitivity of\nMAOS KKR when the domain of integration is truncated to a finite frequency\nwindow. We found that that (i) inferring $G_{33}^{\\prime\\prime}$ from\n$G_{33}^{\\prime}$ is more reliable than vice-versa, (ii) predictions over a\nparticular frequency range require approximately an excess of one decade of\ndata beyond the frequency range of prediction, and (iii) $G_{33}^{\\prime}$ is\nparticularly susceptible to errors at large frequencies."
    },
    {
        "anchor": "DNA topology dictates strength and flocculation in DNA-microtubule\n  composites: Polymer composites are ubiquitous in biology and industry alike, owing to\ntheir emergent desirable mechanical properties not attainable in single-species\nsystems. At the same time, polymer topology has been shown to play a key role\nin tuning the rheology of polymeric fluids. However, how topology impacts the\nrheology of composites remains poorly understood. Here, we create composites of\nrigid rods (microtubules) polymerized within entangled solutions of flexible\nlinear and ring polymers (DNA). We couple linear and nonlinear optical tweezers\nmicrorheology with confocal microscopy and scaled particle theory to show that\ncomposites of linear DNA and microtubules exhibit a strongly non-monotonic\ndependence of elasticity and stiffness on microtubule concentration due to\ndepletion-driven polymerization and flocculation of microtubules. In contrast,\ncomposites of ring DNA and microtubules show a much more modest monotonic\nincrease in elastic strength with microtubule concentration, which we\ndemonstrate arises from the increased ability of rings to mix with\nmicrotubules.",
        "positive": "Unifying framework for strong and fragile liquids via machine learning:\n  a study of liquid silica: The fragility of a glassforming liquid characterizes how rapidly its\nrelaxation dynamics slow down with cooling. The viscosity of strong liquids\nfollows an Arrhenius law with a temperature-independent barrier height to\nrearrangements responsible for relaxation, whereas fragile liquids experience a\nmuch faster increase in their dynamics, suggesting a barrier height that\nincreases with decreasing temperature. Strong glassformers are typically\nnetwork glasses, while fragile glassformers are typically molecular or\nhard-sphere-like. As a result of these differences at the microscopic level,\nstrong and fragile glassformers are usually treated separately from a\ntheoretical point of view. Silica is the archetypal strong glassformer at low\ntemperatures, but also exhibits a mysterious strong-to-fragile crossover at\nhigher temperatures. Here we show that softness, a structure-based machine\nlearned parameter that has previously been applied to fragile glassformers\nprovides a useful description of model liquid silica in the strong and fragile\nregimes, and through the strong-to-fragile crossover. Just as for fragile\nglassformers, the relationship between softness and dynamics is invariant and\nArrhenius in all regimes, but the average softness changes with temperature.\nThe strong-to-fragile crossover in silica is not due to a sudden, qualitative\nchange in structure, but can be explained by a simple Arrhenius form with a\ncontinuously and linearly changing local structure. Our results unify the study\nof liquid silica under a single simple conceptual picture."
    },
    {
        "anchor": "Monte Carlo simulations of the solid-liquid transition in hard spheres\n  and colloid-polymer mixtures: Monte Carlo simulations at constant pressure are performed to study\ncoexistence and interfacial properties of the liquid-solid transition in hard\nspheres and in colloid-polymer mixtures. The latter system is described as a\none-component Asakura-Oosawa (AO) model where the polymer's degrees of freedom\nare incorporated via an attractive part in the effective potential for the\ncolloid-colloid interactions. For the considered AO model, the polymer\nreservoir packing fraction is eta_p^r=0.1 and the colloid-polymer size ratio is\nq=sigma_p/\\sigma=0.15 (with sigma_p and sigma the diameter of polymers and\ncolloids, respectively). Inhomogeneous solid-liquid systems are prepared by\nplacing the solid fcc phase in the middle of a rectangular simulation box\ncreating two interfaces with the adjoined bulk liquid. By analyzing the growth\nof the crystalline region at various pressures and for different system sizes,\nthe coexistence pressure p_co is obtained, yielding p_co=11.576 k_BT/sigma^3\nfor the hard sphere system and p_co=8.0 k_BT/sigma^3 for the AO model (with k_B\nthe Boltzmann constant and T the temperature). Several order parameters are\nintroduced to distinguish between solid and liquid phases and to describe the\ninterfacial properties. From the capillary-wave broadening of the solid-liquid\ninterface, the interfacial stiffness is obtained for the (100) crystalline\nplane, giving the values gamma=0.49 k_BT/sigma^2 for the hard-sphere system and\ngamma=0.95 k_BT/sigma^2 for the AO model.",
        "positive": "Metastability at the Yield-Stress Transition in Soft Glasses: We study the solid-to-liquid transition in a two-dimensional fully periodic\nsoft-glassy model with an imposed spatially heterogeneous stress. The model we\nconsider consists of droplets of a dispersed phase jammed together in a\ncontinuous phase. When the peak value of the stress gets close to the yield\nstress of the material, we find that the whole system intermittently tunnels to\na metastable \"fluidized\" state, which relaxes back to a metastable \"solid\"\nstate by means of an elastic-wave dissipation. This macroscopic scenario is\nstudied through the microscopic displacement field of the droplets, whose time\nstatistics displays a remarkable bimodality. Metastability is rooted in the\nexistence, in a given stress range, of two distinct stable rheological branches\nas well as long-range correlations (e.g., large dynamic heterogeneity)\ndeveloped in the system. Finally, we show that a similar behavior holds for a\npressure-driven flow, thus suggesting possible experimental tests."
    },
    {
        "anchor": "Simulations of living filaments: We propose a hybrid Molecular Dynamics/Multi-particle Collision Dynamics\nmodel to simulate a set of self-assembled semiflexible filaments and free\nmonomers. Further, we introduce a Monte-Carlo scheme to deal with single\nmonomer addition (polymerization) or removal (depolymerization), satisfying the\ndetailed balance condition within a proper statistical mechanical framework.\nThis model of filaments, based on the wormlike chain, aims to represent\nequilibrium polymers with distinct reaction rates at both ends, such as\nself-assembled ADP-actin filaments in the absence of ATP hydrolysis and other\nproteins. We report the distribution of filament lengths and the corresponding\ndynamical fluctuations on an equilibrium trajectory. Potential generalizations\nof this method to include irreversible steps like ATP-actin hydrolysis are\ndiscussed.",
        "positive": "Non-mean-field screening by multivalent counterions: Screening of a strongly charged macroion by its multivalent counterions can\nnot be described in the framework of mean field Poisson-Boltzmann (PB) theory\nbecause multivalent counterions form a strongly correlated liquid (SCL) on the\nsurface of the macroion. It was predicted that a distant counterion polarizes\nthe SCL as if it were a metallic surface and creates an electrostatic image.\nThe attractive potential energy of the image is the reason why the charge\ndensity of counterions decreases faster with distance from the charged surface\nthan in PB theory. Using the Monte Carlo method to find the equilibrium\ndistribution of counterions around the macroion, we confirm the existence of\nthe image potential energy. It is also shown that due to the negative screening\nlength of the SCL, $-2\\xi$, the effective metallic surface is actually above\nthe SCL by $|\\xi|$."
    },
    {
        "anchor": "Screened hydrodynamic interaction in a narrow channel: We study experimentally and theoretically the hydrodynamic coupling between\nBrownian colloidal particles diffusing along a linear channel. The\nquasi-one-dimensional confinement, unlike other constrained geometries, leads\nto a sharply screened interaction. Consequently, particles move in concert only\nwhen their mutual distance is smaller than the channel width, and two-body\ninteractions remain dominant up to high particle densities. The coupling in a\ncylindrical channel is predicted to reverse sign at a certain distance, yet\nthis unusual effect is too small to be currently detectable.",
        "positive": "Soft-core particles freezing to form a quasicrystal and a crystal-liquid\n  phase: Systems of soft-core particles interacting via a two-scale potential are\nstudied. The potential is responsible for peaks in the structure factor of the\nliquid state at two different but comparable length scales, and a similar\nbimodal structure is evident in the dispersion relation. Dynamical density\nfunctional theory in two dimensions is used to identify two novel states of\nthis system, the crystal-liquid state, in which the majority of the particles\nare located on lattice sites but a minority remains free and so behaves like a\nliquid, and a 12-fold quasicrystalline state. Both are present even for deeply\nquenched liquids and are found in a regime in which the liquid is unstable with\nrespect to modulations on the smaller scale only. As a result the system\ninitially evolves towards a small scale crystal state; this state is not a\nminimum of the free energy, however, and so the system subsequently attempts to\nreorganize to generate the lower energy larger scale crystals. This dynamical\nprocess generates a disordered state with quasicrystalline domains, and takes\nplace even when this large scale is linearly stable, i.e., it is a nonlinear\nprocess. With controlled initial conditions a perfect quasicrystal can form.\nThe results are corroborated using Brownian dynamics simulations."
    },
    {
        "anchor": "Worm-like instability of a vibrated sessile drop: We study the effects of vertical sinusoidal vibrations on a liquid droplet\nwith a low surface tension (ethanol) deposited on a solid substrate. In a\nprecise range of amplitudes and frequencies, the drop exhibits a dramatic\nworm-like shape instability with a strong symmetry breaking, comparable to the\none observed by Pucci et al. (Phys. Rev. Lett., 106 (2011) 024503) on a\nvibrated floating lens. However, the geometry of our system is much simpler\nsince it does not involve the oscillation and deformation of a\nliquid-liquid-air contact line. We show that the Faraday waves appearing on the\nsurface of the droplet control its shape and we draw a systematic phase diagram\nof the instability. A simple theoretical model allows us to derive a relation\nbetween the elongation of the droplet and the amplitude of the Faraday wave, in\ngood agreement with measurements of both quantities.",
        "positive": "Tracing chirality from molecular organization to triply-periodic network\n  assemblies: Threading biaxial twist through block copolymer gyroids: Chirality transfer from the level of molecular structure up to mesoscopic\nlengthscales of supramolecular morphologies is a broad and persistent theme in\nself-assembled soft materials, from biological to synthetic matter. Here, we\nanalyze the mechanism of chirality transfer in a prototypical self-assembly\nsystem, block copolymers (BCPs), in particular, its impact on one of the most\ncomplex and functionally vital phases: the cubic, triply-periodic, gyroid\nnetwork. Motivated by recent experimental studies, we consider a\nself-consistent field model of ABC* triblock copolymers possessing an end-block\nof chain chemistry and examine the interplay between chirality at the scale of\nnetworks, in alternating double network phases, and the patterns of segmental\norder within tubular network domains. We show that while segments in gyroids\nexhibit twist in both polar and nematic segmental order parameters, the\nmagnitude of net nematic twist is generically much larger than polar twist, and\nmore surprising, {\\it reverses handedness} relative to the sense of polar order\nas well as the sense of dihedral twist of the network. Careful analysis of the\nintra-domain nematic order reveals that this unique chirality transfer\nmechanism relies on the strongly biaxial nature of segmental order in BCP\nnetworks and relates the {\\it biaxial twist} to complex patterns of frame\nrotation of the principal directors in the intra-domain texture. Finally, we\nshow that this mechanism of twist reversal leads to chirality selection of\nalternating gyroid networks in ABC* triblocks, in the limit of very weak\nchirality ."
    },
    {
        "anchor": "Oscillating edge current in polar active fluid: Dense bacterial suspensions exhibit turbulent behaviour called ``bacterial\nturbulence''. The behavior of the bulk unconstrained bacterial turbulence is\ndescribed well by the Toner-Tu-Swift-Hohenberg (TTSH) equation for the velocity\nfield. However, it remains unclear how we should treat boundary conditions on\nbacterial turbulence in contact with some boundaries (e.g. solid walls). To be\nmore specific, although the importance of the ``edge current'', the flow along\nthe boundary, has been demonstrated in several experimental studies on confined\nbacterial suspensions, previous numerical studies based on the TTSH equation\nemploy non-slip boundary conditions and do not seem to describe properly the\nbehavior of bacteria near the boundaries. In this study, we impose a slip\nboundary condition on the TTSH equation to describe the bacterial motion at\nboundaries. We develop a method to implement the slip boundary condition. Using\nthis method, we have successfully produced edge current and discovered that the\ndirection of the edge current temporally oscillates. The oscillation can be\nattributable to the advection term in the TTSH equation. Our work demonstrates\nthat boundary conditions could play an important role in the collective\ndynamics of active systems.",
        "positive": "Anomalous Diffusion and Stress Relaxation in Surfactant Micelles: We present the first molecular dynamics study to probe the mechanisms of\nanomalous diffusion in cationic surfactant micelles in the presence of explicit\nsalt and solvent-mediated interactions. Simulations show that when the counter\nion density increases, saddle-shaped interfaces manifest leading to the\nformation of branched structures. In experiments, branched structures exhibit\nlower viscosity as compared to linear and wormlike micelles, presumably due to\nstress relaxation arising from the sliding motion of branches along the main\nchain. Our simulations provide conclusive evidence and a mechanism of branch\nmotion and stress relaxation in micellar fluids. Further, depending upon the\nsurfactant and salt concentrations, which in turn determine the microstructure,\nwe observe normal, subdiffusive and superdiffusive motion of surfactants.\nSpecifically, superdiffusive behavior is associated with branch sliding,\nbreakage and recombination of micelle fragments as well as constraint release\nin entangled systems."
    },
    {
        "anchor": "Revisiting fluid-wall interfacial tension: A fluid in contact with a flat structureless wall constitutes the simplest\ninterface system, but the fluid-wall interfacial tension cannot be trivially\nand even unequivocally determined due to the ambiguity in identifying the\nprecise location of fluid-wall dividing surface. To resolve this long-standing\nproblem, we here derive the interfacial tension from two independent routes\nwithout needing the identification of dividing surface. The first one exploits\na natural idea that the interfacial profiles of intensive quantities should\nremain perfectly invariant when deforming the fluid-wall system just to change\nits interface area. The second one considers the fluid-wall system as the limit\nof a fluid under a finite external potential field. By calculating the work\nrequired to create a differential interface area, the two methods yield exactly\nthe same interfacial tension. Thus, our work provides strong evidence that the\nfluid-wall interfacial tension can be unambiguously quantified.",
        "positive": "Coarse-grained model for spring friction study of micron-scale iron by\n  smoothed particle hydrodynamics: The paper constructs a coarse-grained model to investigate dry sliding\nfriction of the body-centered-cubic Fe micron-scale system by smoothed particle\nhydrodynamics simulations and examines influences of the spring force on the\ncharacters of friction. The N_atom = 864 \\times 10^12 atoms Fe system is\ncoarse-grained into the two different simple-cubic particle systems, one of\n432000 and the other of 16000 particles. From the detection of stick-slip\nmotion, friction coefficient, dependence of friction coefficient on isotropy or\nanisotropy of the spring force and externally applied normal load, we find that\nthe coarse-grained model is a reasonable modeling process for study of friction\nof the Fe system and the anisotropic behavior presents better friction of the\nsystem than the isotropic one."
    },
    {
        "anchor": "Concerted motion of protons in hydrogen bonds of DNA-type molecules: We study the dynamical behaviour of the proton transfer in the hydrogen bonds\nin the base-pairs of the double helices of the DNA type. Under the assumption\nthat the elastic and the tunnelling degrees of freedom may be coupled, we\nderive a non-linear and non-local Schrodinger equation (SNLNL) that describes\nthe concerted motion of the proton tunnelling. Rough estimates of the solutions\nto the SNLNL show an intimate interplay between the concerted tunnelling of\nprotons and the symmetry of double helix.",
        "positive": "Dynamics of a $Volvox$ Embryo Turning Itself Inside Out: Spherical embryos of the algal genus $Volvox$ must turn themselves inside out\nto complete their embryogenesis. This `inversion', which shares important\nfeatures with morphological events such as gastrulation in animals, is perhaps\nthe simplest example of a topological transition in developmental biology.\nWaves of cell shape changes are believed to play a major role in the process,\nbut quantification of the dynamics and formulation of a mathematical\ndescription of the process have been lacking. Here, we use selective plane\nillumination microscopy on $V. globator$ to obtain the first quantitative\nthree-dimensional visualizations of inversion $in~vivo$. A theory is formulated\nfor inversion based on local variations of intrinsic curvature and stretching\nof an elastic shell, and for the mechanics of an elastic snap-through resisted\nby the surrounding fluid."
    },
    {
        "anchor": "Shear bands in granular flow through a mixing length model: We discuss the advantages and results of using a mixing-length, compressible\nmodel to account for shear banding behaviour in granular flow. We formulate a\ngeneral approach based on two function of the solid fraction to be determined.\nStudying the vertical chute flow, we show that shear band thickness is always\nindependent from flowrate in the quasistatic limit, for Coulomb wall boundary\nconditions. The effect of bin width is addressed using the functions developed\nby Pouliquen and coworkers, predicting a linear dependence of shear band\nthickness by channel width, while literature reports contrasting data. We also\ndiscuss the influence of wall roughness on shear bands. Through a Coulomb wall\nfriction criterion we show that our model correctly predicts the effect of\nincreasing wall roughness on the thickness of shear bands. Then a simple\nmixing-length approach to steady granular flows can be useful and\nrepresentative of a number of original features of granular flow.",
        "positive": "Adsorption of polymers at nanowires: Low-energy structures of a hybrid system consisting of a polymer and an\nattractive nanowire substrate as well as the thermodynamics of the adsorption\ntransition are studied by means of Monte Carlo computer simulations. Depending\non structural and energetic properties of the substrate, we find different\nadsorbed polymer conformations, amongst which are spherical droplets attached\nto the wire and monolayer tubes surrounding it. We identify adsorption\ntemperatures and the type of the transition between adsorbed and desorbed\nstructures depending on the substrate attraction strength."
    },
    {
        "anchor": "Morphological Phase Separation in Unstable Thin Films: Pattern Formation\n  and Growth: We present results from a comprehensive numerical study of {\\it morphological\nphase separation} (MPS) in unstable thin liquid films on a 2-dimensional\nsubstrate. We study the quantitative properties of the evolution morphology via\nseveral experimentally relevant markers, e.g., correlation function, structure\nfactor, domain-size and defect-size probability distributions, and growth laws.\nOur results suggest that the late-stage morphologies exhibit dynamical scaling,\nand their evolution is self-similar in time. We emphasize the analogies and\ndifferences between MPS in films and segregation kinetics in unstable binary\nmixtures.",
        "positive": "Theory and simulation of the nematic zenithal anchoring coefficient: Combining molecular simulation, Onsager theory and the elastic description of\nnematic liquid crystals, we study the dependence of the nematic liquid crystal\nelastic constants and the zenithal surface anchoring coefficient on the value\nof the bulk order parameter."
    },
    {
        "anchor": "Temperature Protocols to Guide Selective Self-Assembly of Competing\n  Structures: Multi-component self-assembly mixtures offer the possibility of encoding\nmultiple target structures with the same set of interacting components.\nSelective retrieval of one of the stored structures has been attempted by\npreparing an initial state that favours the assembly of the required target,\nthrough seeding, concentration patterning or specific choices of interaction\nstrengths. This may not be possible in an experiment where on-the-fly\nreconfiguration of the building blocks to switch functionality may be required.\nIn this paper, we explore principles of inverse design of a multi-component\nself-assembly mixture capable of encoding two competing structures that can be\nselected through simple temperature protocols. We design the target structures\nto realise the generic situation in which one of targets has the lower\nnucleation barrier while the other is globally more stable. We observe that to\navoid the formation of spurious or chimeric aggregates, the number of\nneighbouring component pairs that occur in both structures should be minimal.\nOur design also requires the inclusion of components that are part only of one\nof the target structures, but we observe that to maximize the selectivity of\nretrieval, the component library itself should be maximally shared by the two\ntargets. We demonstrate that temperature protocols can be designed which lead\nto the formation of either one of the target structures with high selectivity.\nWe discuss the important role played by secondary aggregation products, which\nwe term vestigial aggregates.",
        "positive": "Thermodynamics and its correlation with dynamics in a mean-field model\n  and pinned systems: A comparative study using two different methods of\n  entropy calculation: Recently, some of us developed a novel model glass-forming liquid with k\nextra interactions with pseudo neighbours to each liquid particle over and\nabove the regular interactions with its neighbours. Analysis of the structure\nand dynamics of these systems showed that with an increase in k the systems\nhave more mean-field like properties. This work presents an extensive study of\nthe thermodynamics of the above-mentioned model for several values of k and its\ncorrelation with the dynamics. We surprisingly find that the usual\nthermodynamic integration (TI) method of calculating the entropy provides\nunphysical results for this model. It predicts the vanishing of configurational\nentropy at state points at which both the collective and the single-particle\ndynamics of the system show complete relaxation. We then employ a new method\nknown as the two-phase thermodynamics (2PT) method to calculate the entropy. We\nfind that with an increase in k the difference in the entropy computed using\nthe two methods (2PT and TI) increases. We also find that in the temperature\nrange studied, the entropy calculated via the 2PT method satisfies the\nAdam-Gibbs (AG) relationship between the relaxation time and the\nconfigurational entropy, whereas the entropy calculated via the TI method shows\na strong violation of the same. We then apply the 2PT method to calculate the\nentropy in another system where some fractions of particles are pinned randomly\nin their equilibrium positions. This system also shows a similar breakdown of\nthe AG relationship as reported earlier. We show that the difference in entropy\ncalculated via the 2PT and TI methods increases with an increase in pinning\ndensity. We also find that when the entropy is calculated using the 2PT method,\nthe AG relationship between the dynamics and the entropy holds."
    },
    {
        "anchor": "From wrinkling to global buckling of a ring on a curved substrate: We present a combined analytical approach and numerical study on the\nstability of a ring bound to an annular elastic substrate, which contains a\ncircular cavity. The system is loaded by depressurizing the inner cavity. The\nring is modeled as an Euler-Bernoulli beam and its equilibrium equations are\nderived from the mechanical energy which takes into account both stretching and\nbending contributions. The curvature of the substrate is considered explicitly\nto model the work done by its reaction force on the ring. We distinguish two\ndifferent instabilities: periodic wrinkling of the ring or global buckling of\nthe structure. Our model provides an expression for the critical pressure, as\nwell as a phase diagram that rationalizes the transition between instability\nmodes. Towards assessing the role of curvature, we compare our results for the\ncritical stress and the wrinkling wavelength to their planar counterparts. We\nshow that the critical stress is insensitive to the curvature of the substrate,\nwhile the wavelength is only affected due to the permissible discrete values of\nthe azimuthal wavenumber imposed by the geometry of the problem. Throughout, we\ncontrast our analytical predictions against finite element simulations.",
        "positive": "Dynamical Heterogeneity in a Highly Supercooled Liquid under a Sheared\n  Situation: In the present study, we performed molecular-dynamics simulations and\ninvestigated dynamical heterogeneity in a supercooled liquid under a steady\nshear flow. Dynamical heterogeneity can be characterized by three quantities:\nthe correlation length $\\xi_4(t)$, the intensity $\\chi_4(t)$, and the lifetime\n$\\tau_\\text{hetero}(t)$. We quantified all three quantities by means of the\ncorrelation functions of the particle dynamics, i.e., the four-point\ncorrelation functions, which are extended to the sheared condition. Here, to\ndefine the local dynamics, we used two time intervals $t=\\tau_\\alpha$ and\n$\\tau_{\\text{ngp}}$; $\\tau_\\alpha$ is the $\\alpha$-relaxation time, and\n$\\tau_{\\text{ngp}}$ is the time at which the non-Gaussian parameter of the Van\nHove self-correlation function is maximized. We discovered that all three\nquantities ($\\xi_4(t)$, $\\chi_4(t)$, and $\\tau_\\text{hetero}(t)$) decrease as\nthe shear rate $\\dot{\\gamma}$ of the steady shear flow increases. For the time\ninterval $t=\\tau_\\alpha$, the scalings $\\xi_4(\\tau_\\alpha) \\sim\n\\dot{\\gamma}^{-0.08}$, $\\chi_4(\\tau_\\alpha) \\sim \\dot{\\gamma}^{-0.26}$, and\n$\\tau_\\text{hetero}(\\tau_\\alpha) \\sim \\dot{\\gamma}^{-0.88}$ were obtained. The\nsteady shear flow suppresses the heterogeneous structure as well as the\nlifetime of the dynamical heterogeneity. In addition, our results demonstrated\nthat the $\\alpha$-relaxation time $\\tau_\\alpha$ dependences of three quantities\ncoincide with those at equilibrium. This means that all three quantities of the\ndynamical heterogeneity can be mapped onto those in the equilibrium state\nthrough $\\tau_\\alpha$."
    },
    {
        "anchor": "Folding of a Small Helical Protein Using Hydrogen Bonds and\n  Hydrophobicity Forces: A reduced protein model with five to six atoms per amino acid and five amino\nacid types is developed and tested on a three-helix-bundle protein, a 46-amino\nacid fragment from staphylococcal protein A. The model does not rely on the\nwidely used Go approximation where non-native interactions are ignored. We find\nthat the collapse transition is considerably more abrupt for the protein A\nsequence than for random sequences with the same composition. The chain\ncollapse is found to be at least as fast as helix formation. Energy\nminimization restricted to the thermodynamically favored topology gives a\nstructure that has a root-mean-square deviation of 1.8 A from the native\nstructure. The sequence-dependent part of our potential is pairwise additive.\nOur calculations suggest that fine-tuning this potential by parameter\noptimization is of limited use.",
        "positive": "Polydomain growth at isotropic-nematic transitions in liquid crystalline\n  polymers: We studied the dynamics of isotropic-nematic transitions in liquid\ncrystalline polymers by integrating time-dependent Ginzburg-Landau equations.\nIn a concentrated solution of rodlike polymers, the rotational diffusion\nconstant Dr of the polymer is severely suppressed by the geometrical\nconstraints of the surrounding polymers, so that the rodlike molecules diffuse\nonly along their rod directions. In the early stage of phase transition, the\nrodlike polymers with nearly parallel orientations assemble to form a nematic\npolydomain. This polydomain pattern with characteristic length l, grows with\nself-similarity in three dimensions (3D) over time with a l~1/4 scaling law. In\nthe late stage, the rotational diffusion becomes significant, leading a\ncrossover of the growth exponent from 1/4 to 1/2. This crossover time is\nestimated to be of the order t~1/Dr. We also examined time evolution of a pair\nof disclinations placed in a confined system, by solving the same\ntime-dependent Ginzburg-Landau equations in two dimensions (2D). If the initial\ndistance between the disclinations is shorter than some critical length, they\napproach and annihilate each other; however, at larger initial separations they\nare stabilized."
    },
    {
        "anchor": "Effect of out-of-plane acoustic phonons on the thermal transport\n  properties of graphene: The lattice thermal conductivity of graphene is evaluated using a microscopic\nmodel that takes into account the lattice's discrete nature and the phonon\ndispersion relation within the Brillouin zone. The Boltzmann transport equation\nis solved iteratively within the framework of three-phonon interactions without\ntaking into account the four-phonon scattering process. The Umklapp and normal\ncollisions are treated rigorously, thereby avoiding relaxation-time and\nlong-wavelength approximations. The mechanisms of the failures of these\napproximations in predicting the thermal transport properties are discussed.\nEvaluation of the thermal conductivity is performed at different temperatures\nand frequencies and in different crystallite sizes. Reasonably good agreement\nwith the experimental data is obtained. The calculation reveals a critical role\nof out-of-plane acoustic phonons in determining the thermal conductivity. The\nout-of-plane acoustic phonons contribute greatly and the longitudinal and\ntransverse acoustic phonons make small contributions over a wide range of\ntemperatures and frequencies. The out-of-plane acoustic phonons dominate the\nthermal conductivity due to their high density of states and restrictions\ngoverning the anharmonic phonon scattering. The selection rule severely\nrestricts the phase space for out-of-plane phonon scattering due to reflection\nsymmetry. The optical phonon contribution cannot be neglected at higher\ntemperatures. Both Umklapp and normal processes must be taken into account in\norder to predict the phonon transport properties accurately.",
        "positive": "Nucleation of cadherin clusters on cell-cell interfaces: Cadherins mediate cell-cell adhesion and help the cell determine its shape\nand function. Here we study collective cadherin organization and interactions\nwithin cell-cell contact areas, and find the cadherin density at which a\ngas-liquid phase transition occurs, when cadherin monomers begin to aggregate\ninto dense clusters. We use a 2D lattice model of a cell-cell contact area, and\ncoarse-grain to the continuous number density of cadherin to map the model onto\nthe Cahn-Hilliard coarsening theory. This predicts the density required for\nnucleation, the characteristic length scale of the process, and the number\ndensity of clusters. The analytical predictions of the model are in good\nagreement with experimental observations of cadherin clustering in epithelial\ntissues."
    },
    {
        "anchor": "Dilute Wet Granulates: Nonequilibrium Dynamics and Structure Formation: We investigate a gas of wet granular particles, covered by a thin liquid\nfilm. The dynamic evolution is governed by two-particle interactions, which are\nmainly due to interfacial forces in contrast to dry granular gases. When two\nwet grains collide, a capillary bridge is formed and stays intact up to a\ncertain distance of withdrawal when the bridge ruptures, dissipating a fixed\namount of energy. A freely cooling system is shown to undergo a nonequillibrium\ndynamic phase transition from a state with mainly single particles and fast\ncooling to a state with growing aggregates, such that bridge rupture becomes a\nrare event and cooling is slow. In the early stage of cluster growth,\naggregation is a self-similar process with a fractal dimension of the\naggregates approximately equal to D_f ~ 2. At later times, a percolating\ncluster is observed which ultimately absorbs all the particles. The final\ncluster is compact on large length scales, but fractal with D_f ~ 2 on small\nlength scales.",
        "positive": "2-D Granular Model of Composite Elasticity using Molecular Dynamics\n  Simulation: Composite of two kinds of grains is modeled in two-dimension and the\nelasticity is calculated using molecular dynamics method implementing Gear\npredictor-corrector of fifth order. It has been observed that same composite\nconcentration can be represented by several configurations of the two kinds of\ngrains. Simulation results show a peak or maximum value of a parameter\nproportional to Young's modulus, which quantitatively agrees with reported\nexperiment results. Ratio of used in simulation has influenced average value of\nthe mentioned parameter monotonically, it is increasing as the ratio\nincreasing."
    },
    {
        "anchor": "New jamming scenario: From marginal jamming to deep jamming: We study properties of jammed packings of frictionless spheres over a wide\nrange of volume fractions. There exists a crossover volume fraction which\nseparates deeply jammed solids from marginally jammed solids. In deeply jammed\nsolids, all the scalings presented in marginally jammed solids are replaced\nwith remarkably different ones with potential independent exponents.\nCorrespondingly, there are structural changes in the pair distribution function\nassociated with the crossover. The normal modes of vibration of deeply jammed\nsolids also exhibit some anomalies, e.g. strengthened quasi-localization and\nabsence of Debye-like density of states at low frequencies. Deeply jammed\nsystems may thus be cataloged to a new class of amorphous solids.",
        "positive": "Microscopic theory for the pair correlation function of liquidlike\n  colloidal suspensions under shear flow: We present a theoretical framework to investigate the microscopic structure\nof concentrated hard-sphere colloidal suspensions under strong shear flows by\nfully taking into account the boundary-layer structure of convective diffusion.\nWe solve the pair Smoluchowski equation with shear separately in the\ncompressing and extensional sectors of the solid angle, by means of matched\nasymptotics. A proper, albeit approximate, treatment of the hydrodynamic\ninteractions in the different sectors allows us to construct a potential of\nmean force containing the effect of the flow field on pair correlations. We\ninsert the obtained pair potential in the Percus-Yevick relation and use the\nlatter as a closure to solve the Ornstein-Zernike integral equation. For a wide\nrange of either the packing fraction $\\eta$ and the P\\'eclet ($\\textrm{Pe}$)\nnumber, we compute the pair correlation function and extract scaling laws for\nits value at contact. For all the considered value of $\\textrm{Pe},$ we observe\na very good agreement between theoretical findings and numerical results from\nliterature, up to rather large values of $\\eta.$ The theory predicts a\nconsistent enhancement of the structure factor $ S(k)$ at $k \\to 0,$ upon\nincreasing the $\\textrm{Pe}$ number. We argue this behaviour may signal the\nonset of a phase transition from the isotropic phase to a non-uniform one,\ninduced by the external shear flow."
    },
    {
        "anchor": "Phase Transitions in Nematics: Textures with Tactoids and Disclinations: We demonstrate that a first order isotropic-to-nematic phase transition in\nliquid crystals can be succesfully modeled within the generalized Landau-de\nGennes theory by selecting an appropriate combination of elastic constants. The\nnumerical simulations of the model established in this paper qualitatively\nreproduce the experimentally observed configurations that include interfaces\nand topological defects in the nematic phase.",
        "positive": "Hopping and crawling DNA-coated colloids: Understanding the motion of particles with ligand-receptors is important for\nbiomedical applications and material design. Yet, even among a single design,\nthe prototypical DNA-coated colloids, seemingly similar micrometric particles\nhop or roll, depending on the study. We shed light on this problem by observing\nDNA-coated colloids diffusing near surfaces coated with complementary strands\nfor a wide array of coating designs. We find colloids rapidly switch between 2\nmodes: they hop - with long and fast steps - and crawl - with short and slow\nsteps. Both modes occur at all temperatures around the melting point and over a\nwide array of designs. The particles become increasingly subdiffusive as\ntemperature decreases, in line with subsequent velocity steps becoming\nincreasingly anti-correlated. Overall, crawling (or hopping) phases are more\npredominant at low (or high) temperatures; crawling is also more efficient at\nlow temperatures than hopping to cover large distances. We rationalize this\nbehavior within a simple model: at lower temperatures, the number of bound\nstrands increases, and detachment of all bonds is unlikely, hence, hopping is\nprevented and crawling favored. We thus reveal the mechanism behind a common\ndesign rule relying on increased strand density for long-range self-assembly:\ndense strands on surfaces are required to enable crawling, possibly\nfacilitating particle rearrangements."
    },
    {
        "anchor": "Hyperuniform Density Distributions of Brownian Particles via Designer\n  External Potentials: Disordered hyperuniformity (DHU) is a recently discovered novel state of\nmany-body systems that is characterized by vanishing normalized\ninfinite-wavelength density fluctuations similar to a perfect crystal, yet\npossesses an amorphous structure like a liquid or glass. Here we investigate\nequilibrium DHU states of Brownian particles induced by external potentials. In\nparticular, we analytically derive sufficient conditions on the external\npotentials in order to achieve distinct classes of DHU density distributions of\nBrownian particles in thermal equilibrium, based on the stationary-state\nsolutions of the corresponding Smoluchowski equation. We show for a wide\nspectrum of tight-binding potentials, the desirable DHU states of Brownian\nparticles can be controlled and achieved by imposing proper hyperuniformity\nconditions on the potentials. Moreover, we find that thermal motions in these\nsystems tend to enhance hyperuniformity. We also analyze the evolution dynamics\nof an initial density distribution (hyperuniform or non-hyperuniform) to the\ndesirable equilibrium DHU state determined by the prescribed external\npotentials, which is shown to be coupled with the full spectra of the force\nfields associated with the imposed potentials. We find that although the\ntransient density distribution can rapidly develop local patterns reminiscent\nof those in the equilibrium distribution, which is governed by the fast\ndynamics induced by the external potential, the overall distribution is still\nmodulated by the initial density fluctuations which are relaxed through slow\ndiffusive dynamics. Our study has implications for the fabrication of designer\nDHU materials.",
        "positive": "Strong Coupling Electrostatics in the Presence of Dielectric\n  Inhomogeneities: We study the strong-coupling (SC) interaction between two like-charged\nmembranes of finite thickness embedded in a medium of higher dielectric\nconstant. A generalized SC theory is applied along with extensive Monte-Carlo\nsimulations to study the image charge effects induced by multiple dielectric\ndiscontinuities in this system. These effects lead to strong counterion\ncrowding in the central region of the inter-surface space upon increasing the\nsolvent/membrane dielectric mismatch and change the membrane interactions from\nattractive to repulsive at small separations. These features agree\nquantitatively with the SC theory at elevated couplings or dielectric mismatch\nwhere the correlation hole around counterions is larger than the thickness of\nthe central counterion layer."
    },
    {
        "anchor": "Excess entropy determines the applicability of Stokes-Einstein relation\n  in simple fluids: The Stokes-Einstein (SE) relation between the self-diffusion and shear\nviscosity coefficients operates in sufficiently dense liquids not too far from\nthe liquid-solid phase transition. By considering four simple model systems\nwith very different pairwise interaction potentials (Lennard-Jones, Coulomb,\nDebye-H\\\"uckel or screened Coulomb, and the hard sphere limit) we identify\nwhere exactly on the respective phase diagrams the SE relation holds. It\nappears that the reduced excess entropy $s_{\\rm ex}$ can be used as a suitable\nindicator of the validity of the SE relation. In all cases considered the onset\nof SE relation validity occurs at approximately $s_{\\rm ex}\\lesssim -2$. In\naddition, we demonstrate that the line separating gas-like and liquid-like\nfluid behaviours on the phase diagram is roughly characterized by $s_{\\rm\nex}\\simeq -1$.",
        "positive": "Athermal Phase Separation of Self-Propelled Particles with no Alignment: We study numerically and analytically a model of self-propelled polar disks\non a substrate in two dimensions. The particles interact via isotropic\nrepulsive forces and are subject to rotational noise, but there is no aligning\ninteraction. As a result, the system does not exhibit an ordered state. The\nisotropic fluid phase separates well below close packing and exhibits the large\nnumber fluctuations and clustering found ubiquitously in active systems. Our\nwork shows that this behavior is a generic property of systems that are driven\nout of equilibrium locally, as for instance by self propulsion."
    },
    {
        "anchor": "The Raspberry Model for Hydrodynamic Interactions Revisited. I. Periodic\n  Arrays of Spheres and Dumbbells: The so-called 'raspberry' model refers to the hybrid lattice-Boltzmann and\nLangevin molecular dynamics scheme for simulating the dynamics of suspensions\nof colloidal particles, originally developed by [V. Lobaskin and B. D\\\"unweg,\nNew J. Phys. 6, 54 (2004)], wherein discrete surface points are used to achieve\nfluid-particle coupling. This technique has been used in many simulation\nstudies on the behavior of colloids. However, there are fundamental questions\nwith regards to the use of this model. In this paper, we examine the accuracy\nwith which the raspberry method is able to reproduce Stokes-level hydrodynamic\ninteractions when compared to analytic expressions for solid spheres in\nsimple-cubic crystals. To this end, we consider the quality of numerical\nexperiments that are traditionally used to establish these properties and we\ndiscuss their shortcomings. We show that there is a discrepancy between the\ntranslational and rotational mobility reproduced by the simple raspberry model\nand present a way to numerically remedy the problem by adding internal coupling\npoints. Finally, we examine a non-convex shape, namely a colloidal dumbbell,\nand show that the filled raspberry model replicates the desired hydrodynamic\nbehavior in bulk for this more complicated shape. Our investigation is\ncontinued in [J. de Graaf, et al., J. Chem. Phys. 143, 084107 (2015)], wherein\nwe consider the raspberry model in the confining geometry of two parallel\nplates.",
        "positive": "Polymer segregation under confinement: Free energy calculations and\n  segregation dynamics simulations: Monte Carlo simulations are used to study the behavior of two polymers under\nconfinement in a cylindrical tube. Each polymer is modeled as a chain of hard\nspheres. We measure the free energy of the system, F, as a function of the\ndistance between the centers of mass of the polymers, lambda, and examine the\neffects on the free energy functions of varying the channel diameter D and\nlength L, as well as the polymer length N and bending rigidity, kappa. For\ninfinitely long cylinders, F is a maximum at lambda=0, and decreases with\nlambda until the polymers are no longer in contact. For flexible chains, the\npolymers overlap along the cylinder for low lambda, while above some critical\nvalue of lambda they are longitudinally compressed and non-overlapping while\nstill in contact. We find that the free energy barrier height, scales as Delta\nF/k_BT~ND^{-1.93+/-0.01}. In addition, the overlap free energy scales as\nF/k_BT=Nf(lambda/N;D), where f is a function parameterized by D. For channels\nof finite L, the free energy barrier height increases with increasing\nconfinement aspect ratio L/D at fixed volume fraction phi, and it decreases\nwith increasing phi at fixed L/D. Increasing the polymer bending rigidity kappa\nmonotonically reduces the overlap free energy. For strongly confined systems, F\nvaries linearly with lambda with a slope that scales as F'(lambda)~-k_BT\nD^{-beta} P^{-alpha}, where beta approx 2 and alpha approx 0.37 for N=200\nchains. These exponent values deviate slightly from those predicted using a\nsimple model, possibly due to insufficiently satisfying the conditions defining\nthe Odijk regime. Finally, we use Monte Carlo dynamics simulations to examine\npolymer segregation dynamics for fully flexible chains and observe segregation\nrates that decrease with decreasing entropic force magnitude. The polymers are\nnot conformationally relaxed at later times during segregation."
    },
    {
        "anchor": "Dynamics of Diblock Copolymers in Dilute Solutions: We consider the dynamics of freely translating and rotating diblock (A-B),\nGaussian copolymers, in dilute solutions. Using the multiple scattering\ntechnique, we have computed the diffusion and the friction coefficients D_AB\nand Zeta_AB, and the change Eta_AB in the viscosity of the solution as\nfunctions of x = N_A/N and t = l_B/l_A, where N_A, N are the number of segments\nof the A block and of the whole copolymer, respectively, and l_A, l_B are the\nKuhn lengths of the A and B blocks. Specific regimes that maximize the\nefficiency of separation of copolymers with distinct \"t\" values, have been\nidentified.",
        "positive": "Flocking Transition in Confluent Tissues: Collective cell migration underlies important biological processes, such as\nembryonic development, wound healing and cancer invasion. While many aspects of\nsingle cell movements are now well established, the mechanisms leading to\ndisplacements of cohesive cell groups are still poorly understood. To elucidate\nthe emergence of collective migration in mechanosensitive cells, we examine a\nself-propelled Voronoi (SPV) model of confluent tissues with an orientational\nfeedback that aligns a cell's polarization with its local migration velocity.\nWhile shape and motility are known to regulate a density-independent\nliquid-solid transition in tissues, we find that aligning interactions\nfacilitate collective motion and promote solidification. Our model reproduces\nthe behavior observed in jammed epithelial monolayers, which are unjammed by\nthe addition of the endocytic protein RAB5A that promotes cell motility by\ninducing large scale coherent migratory patterns and local fluidization."
    },
    {
        "anchor": "Swirling Instability of the Microtubule Cytoskeleton: In the cellular phenomena of cytoplasmic streaming, molecular motors carrying\ncargo along a network of microtubules entrain the surrounding fluid. The\npiconewton forces produced by individual motors are sufficient to deform long\nmicrotubules, as are the collective fluid flows generated by many moving\nmotors. Studies of streaming during oocyte development in the fruit fly\n$D.~melanogaster$ have shown a transition from a spatially-disordered\ncytoskeleton, supporting flows with only short-ranged correlations, to an\nordered state with a cell-spanning vortical flow. To test the hypothesis that\nthis transition is driven by fluid-structure interactions we study a\ndiscrete-filament model and a coarse-grained continuum theory for motors moving\non a deformable cytoskeleton, both of which are shown to exhibit a\n$swirling~instability$ to spontaneous large-scale rotational motion, as\nobserved.",
        "positive": "Stochastic model for the alignment and tumbling of rigid fibres in\n  two-dimensional turbulent shear flow: Non-spherical particles transported by an anisotropic turbulent flow\npreferentially align with the mean shear and intermittently tumble when the\nlocal strain fluctuates. Such an intricate behaviour is here studied for\ninertialess, rod-shaped particles embedded in a two-dimensional turbulent flow\nwith homogeneous shear. A Lagrangian stochastic model for the rods angular\ndynamics is introduced and compared to the results of direct numerical\nsimulations. The model consists in superposing a short-correlated random\ncomponent to the steady large-scale mean shear, and can thereby be integrated\nanalytically. To reproduce the single-time orientation statistics obtained\nnumerically, it is found that one has to properly account for the combined\neffect of the mean shear, for anisotropic velocity gradient fluctuations, and\nfor the presence of persistent rotating structures in the flow that bias\nLagrangian statistics. The model is then used to address two-time statistics.\nThe notion of tumbling rate is extended to diffusive dynamics by introducing\nthe stationary probability flux of the rods unfolded angle. The model is found\nto reproduce the long-term effects of an average shear on the mean and the\nvariance of the fibres angular increment. Still, it does not reproduce an\nintricate behaviour observed in numerics for intermediate times: the unfolded\nangle is there very similar to a L\\'evy walk with distributions of increments\ndisplaying intermediate power-law tails."
    },
    {
        "anchor": "Tensional twist-folding of sheets into multilayered scrolled yarns: Twisting sheets as a strategy to form functional yarns relies on millennia of\nhuman practice in making catguts and fabric wearables, but still lacks\noverarching principles to guide their intricate architectures. We show that\ntwisted hyperelastic sheets form multilayered self-scrolled yarns, through\nrecursive folding and twist localization, that can be reconfigured and\nredeployed. We combine weakly nonlinear elasticity and origami to explain the\nobserved ordered progression beyond the realm of perturbative models.\nIncorporating dominant stretching modes with folding kinematics, we explain the\nmeasured torque and energetics originating from geometric nonlinearities due to\nlarge displacements. Complementarily, we show that the resulting structures can\nbe algorithmically generated using Schl\\\"afli symbols for star-shaped polygons.\nA geometric model is then introduced to explain the formation and structure of\nself-scrolled yarns. Our tensional twist-folding framework shows that origami\ncan be harnessed to understand the transformation of stretchable sheets into\nself-assembled architectures with a simple twist.",
        "positive": "Quasi-2D dynamic jamming in cornstarch suspensions: visualization and\n  force measurements: We report experiments investigating jamming fronts in a floating layer of\ncornstarch suspension. The suspension has a packing fraction close to jamming,\nwhich dynamically turns into a solid when impacted at a high speed. We show\nthat the front propagates in both axial and transverse direction from the point\nof impact, with a constant ratio between the two directions of propagation of\napproximately 2. Inside the jammed solid, we observe an additional compression,\nwhich results from the increasing stress as the solid grows. During the initial\ngrowth of the jammed solid, we measure a force response that can be completely\naccounted for by added mass. Only once the jamming front reaches a boundary,\nthe added mass cannot account for the measured force anymore. We do not,\nhowever, immediately see a strong force response as we would expect when\ncompressing a jammed packing. Instead, we observe a delay in the force response\non the pusher, which corresponds to the time it takes for the system to develop\na close to uniform velocity gradient that spans the complete system."
    },
    {
        "anchor": "Effect of hydrophobic solutes on the liquid-liquid critical point: Jagla ramp particles, interacting through a ramp potential with two\ncharacteristic length scales, are known to show in their bulk phase\nthermodynamic and dynamic anomalies, similar to what is found in water. Jagla\nparticles also exhibit a line of phase transitions separating a low density\nliquid phase and a high density liquid phase, terminating in a liquid-liquid\ncritical point in a region of the phase diagram that can be studied by\nsimulations. Employing molecular dynamics computer simulations, we study the\nthermodynamics and the dynamics of solutions of hard spheres (HS) in a solvent\nformed by Jagla ramp particles. We consider the cases of HS mole fraction x =\n0.10, 0.15 and 0.20, and also the case x = 0.50 (a 1:1 mixture of HS and Jagla\nparticles). We find a liquid-liquid critical point, up to the highest HS mole\nfraction; its position shifts to higher pressures and lower temperatures upon\nincreasing x. We also find that the diffusion coefficient anomalies appear to\nbe preserved for all the mole fractions studied.",
        "positive": "Star polymers in correlated disorder: We analyze the impact of a porous medium (structural disorder) on the scaling\nof the partition function of a star polymer immersed in a good solvent. We show\nthat corresponding scaling exponents change if the disorder is\nlong-range-correlated and calculate the exponents in the new universality\nclass. A notable finding is that star and chain polymers react in qualitatively\ndifferent manner on the presence of disorder: the corresponding scaling\nexponents increase for chains and decrease for stars. We discuss the physical\nconsequences of this difference."
    },
    {
        "anchor": "Line tension of branching junctions of bilayer membranes: Branching of bilayer membranes appear in the inverted hexagonal phase as well\nas in metastable states of the lamellar phase such as membrane fusion\nintermediates. A method for estimating the line tension of the branching\njunction is proposed for molecular simulations. The line tension is calculated\nfrom the pressure tensor of equiangularly branched membranes. The simulation\nresults agree very well with the theoretical prediction of Hamm and Kozlov's\ntilt model. The transition between the lamellar and inverted hexagonal phases\nis also investigated using the tilt model.",
        "positive": "Topological fine structure of smectic grain boundaries and tetratic\n  disclination lines within three-dimensional smectic liquid crystals: Observing and characterizing the complex ordering phenomena of liquid\ncrystals subjected to external constraints constitutes an ongoing challenge for\nchemists and physicists alike. To elucidate the delicate balance appearing when\nthe intrinsic positional order of smectic liquid crystals comes into play, we\nperform Monte-Carlo simulations of rod-like particles in a range of cavities\nwith a cylindrical symmetry. Based on recent insights into the topology of\nsmectic orientational grain boundaries in two dimensions, we analyze the\nemerging three-dimensional defect structures from the perspective of tetratic\nsymmetry. Using an appropriate three-dimensional tetratic order parameter\nconstructed from the Steinhardt order parameters, we show that those grain\nboundaries can be interpreted as a pair of tetratic disclination lines that are\nlocated on the edges of the nematic domain boundary. Thereby, we shed light on\nthe fine structure of grain boundaries in three-dimensional confined smectics."
    },
    {
        "anchor": "Formation of Colloidal Chains and Driven Clusters with Optical Binding: We study the effects of the optical binding force on wavelength sized\ncolloidal particles free to move in a counter-propagating beam. This work is\nmotivated by the concept of using optical binding to direct the assembly of\nlarge numbers of colloidal particles; previous work has used small numbers of\nparticles and/or 1D or 2D restricted geometries. Utilizing a novel experimental\nscheme, we describe the general static and dynamic self-organization behaviors\nfor 20--100 particles free to move in 3-dimensional space. We observe the\nself-organization of the colloids into large optically bound structures along\nwith the formation of driven particle clusters. Furthermore we show that the\nstructure and behavior of these optically bound systems can be tuned using the\nrefractive index of the particles and properties of the binding light. In\nparticular, we show that the driven behavior originates from $N$-body\ninteractions, which has significant implications for future work on optically\nbound clusters of more than 2 particles.",
        "positive": "On the impact of controlled wall roughness shape on the flow of a\n  soft-material: We explore the impact of geometrical corrugations on the near-wall flow\nproperties of a soft-material driven in a confined rough microchannel. By means\nof numerical simulations, we perform a quantitative analysis of the relation\nbetween the flow rate $\\Phi$ and the wall stress $\\sigma_w$ for a number of\nsetups, by changing both the roughness values as well as the roughness shape.\nRoughness suppresses the flow, with the existence of a characteristic value of\n$\\sigma_w$ at which flow sets in. Just above the onset of flow, we\nquantitatively analyze the relation between $\\Phi$ and $\\sigma_w$. While for\nsmooth walls a linear dependency is observed, steeper behaviours are found to\nset in by increasing wall roughness. The variation of the steepness, in turn,\ndepends on the shape of the wall roughness, wherein gentle steepness changes\nare promoted by a variable space localization of the roughness."
    },
    {
        "anchor": "Conformational rearrangements in thin films of polydimethylsiloxane melt: Synchrotron X-ray reflectivity (XRR) confirms the formation of a\nquasi-immobilized layer in thin films of polydimethylsiloxane (PDMS) melts near\nsilica surfaces. This layer (40-60A) has a lower density than the bulk value,\nand its thickness varies slightly with PDMS molecular weight. Formation of this\nlayer is very rapid for PDMS melts with low molecular weights (below\nentanglement limit for these molecules) but takes 5-10 hours for higher\nmolecular weights (close to and above their entanglement value).",
        "positive": "On the effect of boundaries on noninteracting weakly active particles in\n  different geometries: We study analytically how noninteracting weakly active particles, for which\npassive Brownian diffusion cannot be neglected and activity can be treated\nperturbatively, distribute and behave near boundaries in various geometries. In\nparticular, we develop a perturbative approach for the model of active\nparticles driven by an exponentially correlated random force (active\nOrnstein-Uhlenbeck particles). This approach involves a relatively simple\nexpansion of the distribution in powers of the P\\'{e}clet number and in terms\nof Hermite polynomials. We use this approach to cleanly formulate boundary\nconditions, which allows us to study weakly active particles in several\ngeometries: confinement by a single wall or between two walls in 1D,\nconfinement in a circular or wedge-shaped region in 2D, motion near a\ncorrugated boundary, and finally absorption onto a sphere. We consider how\nquantities such as the density, pressure, and flow of the active particles\nchange as we gradually increase the activity away from a purely passive system.\nThese results for the limit of weak activity help us gain insight into how\nactive particles behave in the presence of various types of boundaries."
    },
    {
        "anchor": "Roadmap on machine learning glassy liquids: Unraveling the connections between microscopic structure, emergent physical\nproperties, and slow dynamics has long been a challenge in the field of the\nglass transition. The absence of clear visible structural order in amorphous\nconfigurations complicates the identification of the key features related to\nstructural relaxation and transport properties. The difficulty in sampling\nequilibrated configurations at low temperatures hampers thorough numerical and\ntheoretical investigations. This roadmap article explores the potential of\nmachine learning (ML) techniques to face these challenges, building on the\nalgorithms that have revolutionized computer vision and image recognition. We\npresent successful ML applications, as well as many open problems for the\nfuture, such as transferability and interpretability of ML approaches. We\nhighlight new ideas and directions in which ML could provide breakthroughs to\nbetter understand glassy liquids. To foster a collaborative community effort,\nthe article introduces the \"GlassBench\" dataset, providing simulation data and\nbenchmarks for both two-dimensional and three-dimensional glass-formers.\nEmphasizing the importance of benchmarks, we identify critical metrics for\ncomparing the performance of emerging ML methodologies, in line with\nbenchmarking practices in image and text recognition. The goal of this roadmap\nis to provide guidelines for the development of ML techniques in systems\ndisplaying slow dynamics, while inspiring new directions to improve our\nunderstanding of glassy liquids.",
        "positive": "Polymer models with optimal good-solvent behavior: We consider three different continuum polymer models, that all depend on a\ntunable parameter r that determines the strength of the excluded-volume\ninteractions. In the first model chains are obtained by concatenating hard\nspherocylinders of height b and diameter rb (we call them thick self- avoiding\nchains). The other two models are generalizations of the tangent hard-sphere\nand of the Kremer-Grest models. We show that, for a specific value r*, all\nmodels show an optimal behavior: asymptotic long-chain behavior is observed for\nrelatively short chains. For r < r*, instead, the behavior can be parametrized\nby using the two-parameter model that also describes the thermal crossover\nclose to the {\\theta} point. The bonds of thick self-avoiding chains cannot\ncross each other and, therefore, the model is suited for the investigation of\ntopological properties and for dynamical studies. Such a model also provides a\ncoarse-grained description of double-stranded DNA, so that we can use our\nresults to discuss under which conditions DNA can be considered as a model\ngood-solvent polymer."
    },
    {
        "anchor": "Self-assembly of hard helices: a rich and unconventional polymorphism: Hard helices can be regarded as a paradigmatic elementary model for a number\nof natural and synthetic soft matter systems, all featuring the helix as their\nbasic structural unit: from natural polynucleotides and polypeptides to\nsynthetic helical polymers; from bacterial flagella to colloidal helices. Here\nwe present an extensive investigation of the phase diagram of hard helices\nusing a variety of methods. Isobaric Monte Carlo numerical simulations are used\nto trace the phase diagram: on going from the low-density isotropic to the\nhigh-density compact phases, a rich polymorphism is observed exhibiting a\nspecial chiral screw-like nematic phase and a number of chiral and/or polar\nsmectic phases. We present a full characterization of the latter, showing that\nthey have unconventional features, ascribable to the helical shape of the\nconstituent particles. Equal area construction is used to locate the\nisotropic-to-nematic phase transition, and results are compared with those\nstemming from an Onsager-like theory. Density functional theory is also used to\nstudy the nematic-to-screw-nematic phase transition: within the simplifying\nassumption of perfectly parallel helices, we compare different levels of\napproximation, that is second- and third-virial expansions and Parsons-Lee\ncorrection.",
        "positive": "Tube Width Fluctuations in F-Actin Solutions: We determine the statistics of the local tube width in F-actin solutions,\nbeyond the usually reported mean value. Our experimental observations are\nexplained by a segment fluid theory based on the binary collision approximation\n(BCA). In this systematic generalization of the standard mean-field approach\neffective polymer segments interact via a potential representing the\ntopological constraints. The analytically predicted universal tube width\ndistribution with a stretched tail is in good agreement with the data."
    },
    {
        "anchor": "GHz sample excitation at the ALBA-PEEM: We describe a setup that is used for high-frequency electrical sample\nexcitation in a cathode lens electron microscope with the sample stage at high\nvoltage as used in many synchrotron light sources. Electrical signals are\ntransmitted by dedicated high-frequency components to the printed circuit board\nsupporting the sample. Sub-miniature push-on connectors (SMP) are used to\nrealize the connection in the ultra-high vacuum chamber, bypassing the standard\nfeedthrough. A bandwidth up to 4 GHz with -6 dB attenuation was measured at the\nsample position, which allows to apply sub-nanosecond pulses. We describe\ndifferent electronic sample excitation schemes and demonstrate a spatial\nresolution of 56 nm employing the new setup.",
        "positive": "Gravity-driven instability in a spherical Hele-Shaw cell: A pair of concentric spheres separated by a small gap form a spherical\nHele-Shaw cell. In this cell an interfacial instability arises when two\nimmiscible fluids flow. We derive the equation of motion for the interface\nperturbation amplitudes, including both pressure and gravity drivings, using a\nmode coupling approach. Linear stability analysis shows that mode growth rates\ndepend upon interface perimeter and gravitational force. Mode coupling analysis\nreveals the formation of fingering structures presenting a tendency toward\nfinger tip-sharpening."
    },
    {
        "anchor": "Freedericksz-like positional transition of a micro-droplet suspended in\n  a nematic cell: In this paper, a Freedericksz-like positional transition is found for a\nspherical micro-droplet suspended in a nematic liquid crystal cell in the\npresence of an external electric field. Based on the numerical calculation of\nelastic energy using Green function method, the equilibrium position of\nmicro-droplet is decided through a competition between the buoyant force and\nthe effective force built by the elastic energy gradient existing inside the\nnematic liquid crystal(NLC) cell. It is shown that the elastic energy dominates\nthe kinetics of micro-droplet until the external field applied reaches a\ncritical value large enough to flatten the elastic energy contour in the\ncentral region, which enables the asymmetric buoyant force to drive the liquid\ndroplet abruptly from the cell midplane to a new equilibrium position. It is\nalso found that such a threshold value of external field, which triggers\npositional transition, depends on thickness $L$ and Frank elastic constant $K$,\nin a Freedericksz-like manner, but multiplied by a factor of $3\\sqrt{\\pi}$. An\nexplicit formula proposed for the critical electric field agrees extremely well\nwith the numerical calculation.",
        "positive": "Local Energy Landscape in a Simple Liquid: It is difficult to relate the properties of liquids and glasses directly to\ntheir structure because of complexity in the structure which defies precise\ndefinition. The potential energy landscape (PEL) approach is a very insightful\nway to conceptualize the structure-property relationship in liquids and\nglasses, particularly on the effect of temperature and history. However,\nbecause of the highly multi-dimensional nature of the PEL it is hard to\ndetermine, or even visualize, the actual details of the energy landscape. In\nthis article we introduce a modified concept of the local energy landscape\n(LEL) which is limited in phase space, and demonstrate its usefulness using\nmolecular dynamics simulation on a simple liquid at high temperatures. The\nlocal energy landscape is given as a function of the local coordination number,\nthe number of the nearest neighbor atoms. The excitations in the LEL\ncorresponds to the so-called beta-relaxation process. The LEL offers a simple\nbut useful starting point to discuss complex phenomena in liquids and glasses."
    },
    {
        "anchor": "Microscopic Origin of the Hofmeister Effect in Gelation Kinetics of\n  Colloidal Silica: The gelation kinetics of silica nanoparticles is a central process in\nphysical chemistry, yet it is not fully understood. Gelation times are measured\nto increase by over 4 orders of magnitude, simply changing the monovalent salt\nspecies from CsCl to LiCl. This striking effect has no microscopic explanation\nwithin current paradigms. The trend is consistent with the Hofmeister series,\npointing to short-ranged solvation effects not included in the standard\ncolloidal (DLVO) interaction potential. By implementing a simple form for\nshort-range repulsion within a model that relates the gelation timescale to the\ncolloidal interaction forces, we are able to explain the many orders of\nmagnitude difference in the gelation times at fixed salt concentration. The\nmodel allows us to estimate the magnitude of the non-DLVO hydration forces,\nwhich dominate the interparticle interactions on the length scale of the\nhydrated ion diameter. This opens the possibility of finely tuning the gelation\ntime scale of nanoparticles by just adjusting the background electrolyte\nspecies",
        "positive": "Nonequilibrium steady states of the isotropic classical magnet: We drive a d-dimensional Heisenberg magnet using a spatially anisotropic\ncurrent of mobile particles or heat. The continuum Langevin equation is\nanalyzed using a dynamical renormalization group, stability analysis and\nnumerical simulations. We discover a rich steady-state phase diagram, including\na critical point in a new nonequilibrium universality class, and a\nspatiotemporally chaotic phase. The latter may be `controlled' in a robust\nmanner to target spatially periodic steady states with helical order. We\ndiscuss several physical realizations of this model and make definite\npredictions which could be tested in experimental or model lattice systems."
    },
    {
        "anchor": "Fluctuation-Driven 1st-Order Isotropic-to-Tetrahedratic Phase Transition: Motivated in part by recent experiments on liquid crystals with bent-core\nmolecules, which are observed to display a spontaneous chiral symmetry\nbreaking, we introduce a field theory of a 3rd-rank tensor order parameter\nT^{ijk} to describe the isotropic-to-tetrahedratic phase transition that we\npredict to take place in these materials. We study the critical properties of\nthe corresponding phase transition and find that this transition, continuous at\nthe mean-field level, is generically driven 1st-order by thermal fluctuations.",
        "positive": "Edge instability in incompressible planar active fluids: Interfacial instability is highly relevant to many important biological\nprocesses. A key example arises in wound healing experiments, which observe\nthat an epithelial layer with an initially straight edge does not heal\nuniformly. We consider the phenomenon in the context of active fluids.\nImproving upon the approximation used in J. Zimmermann, M. Basan and H. Levine,\nEuro. Phys. J.: Special Topics 223, 1259 (2014), we perform a linear stability\nanalysis on a two dimensional incompressible hydrodynamic model of an active\nfluid with an open interface. We categorise the stability of the model and find\nthat for experimentally relevant parameters, fingering stability is always\nabsent in this minimal model. Our results point to the crucial importance of\ndensity variation in the fingering instability in tissue regeneration."
    },
    {
        "anchor": "On the interaction of viscoelasticity and waviness in enhancing the\n  pull-off force in sphere/flat contacts: Motivated by roughness-induced adhesion enhancement (toughening and\nstrengthening) in low modulus materials, we study the detachment of a sphere\nfrom a substrate in the presence of both viscoelastic dissipation at the\ncontact edge, and roughness in the form of a single axisymmetric waviness. We\nshow that the roughness-induced enhancement found by Guduru and coworkers for\nthe elastic case (i.e. at very small detachment speeds) tends to disappear with\nincreasing speeds, where the viscoelastic effect dominates and the problem\napproaches that of a smooth sphere. This is in qualitative agreement with the\noriginal experiments of Guduru's group with gelatin. The cross-over velocity is\nwhere the two separate effects are comparable. Viscoelasticity effectively\ndamps roughness-induced elastic instabilities, and make their effects much less\nimportant.",
        "positive": "Structure and Aggregation of a Helix-Forming Polymer: We have studied the competition between helix formation and aggregation for a\nsimple polymer model. We present simulation results for a system of two such\npolymers, examining the potential of mean force, the balance between inter and\nintramolecular interactions, and the promotion or disruption of secondary\nstructure brought on by the proximity of the two molecules. In particular, we\ndemonstrate that proximity between two such molecules can stabilize secondary\nstructure. However, for this model, observed secondary structure is not stable\nenough to prevent collapse of the system into an unstructured globule."
    },
    {
        "anchor": "Stress propagation in granular media: Breaking of any constitutive state\n  equation relating local stresses together by a change of boundary conditions: The stress response of a granular assembly subject to different changes of\nboundary conditions is studied experimentally in order to define the stress\npropagation characteristics. These results demonstrate that no simple and\nsingle relationship between local stresses exists, which would be imposed by\nthe local structure of the granular assembly only in general. On the contrary,\nit is demonstrated that these results are controlled by the boundary conditions\nthemselves and that a tiny change of them may lead to strong variations in the\nincrememental stress relation; furthermore, in other cases, these changes may\ngenerate large variations of the stress field and can allow to understand\npartly the fluctuations already observed in these media. PACS: 46.10+z ;\n46.30.-i ; 81.05.Rm",
        "positive": "A crossover of the solid substances solubility in supercritical fluids:\n  what is it in fact?: We investigate a well-known phenomenon of the appearance of the crossover\npoints, corresponding to the intersections of the solubility isotherms of the\nsolid compound in supercritical fluid. Opposed to the accepted understanding of\nthe existence of two fixed crossover points, which confine the region of the\ninverse isobaric temperature dependence of the solubility, we have found that\nthese points tend to shift with the change of the temperature and in the limit\nof the certain threshold value they converge to a single point. We demonstrate\nthis analyzing the solubility data of a set of poorly soluble drug compounds,\nwhich have been computed in a wide area of the phase diagram via the approach,\nbased on the classical density functional theory. Thorough analysis of the\navailable in the literature experimental solubility data is found to be in an\nagreement with our conclusions, as one can find that the wider temperature\nregion of the experimental study is, the more pronounced effect of the\ncrossover points drift can be observed."
    },
    {
        "anchor": "Light-induced self-assembly of active rectification devices: Self-propelled colloidal objects, such as motile bacteria or synthetic\nmicroswimmers, have microscopically irreversible individual dynamics - a\nfeature they share with all living systems. The incoherent behaviour of\nindividual swimmers can then be harnessed (or \"rectified\") by microfluidic\ndevices that create systematic motions impossible in equilibrium. Examples\ninclude flow of rotor particles round a circuit, steady rotation of a gear\nwheel in a bacterial bath, and pumping of bacteria between chambers by \"funnel\ngates\". Here we present a computational proof-of-concept study, showing that\nsuch active rectification devices might be created directly from an\nunstructured \"primordial soup\" of motile particles, solely by using spatially\nmodulated illumination to control their local propulsion speed. Alongside both\nmicroscopic irreversibility and speed modulation, our mechanism requires\nspatial symmetry breaking, such as a chevron light pattern, and strong\ninteractions between particles, such as volume exclusion causing a collisional\nslow-down at high density. These four factors create a many-body rectification\nmechanism that generically differs from one-body microfluidic antecedents. Our\nwork suggests that standard spatial-light-modulator technology might allow the\nprogrammable, light-induced self-assembly of active rectification devices from\nan unstructured particle bath.",
        "positive": "Oscillating Superfluidity of Bosons in Optical Lattices: We follow up on a recent suggestion by C. Orzel et. al., Science, 291, 2386\n(2001), whereby bosons in an optical lattice would be subjected to a sudden\nparameter change from the Mott to the superfluid phase. We analyze the Bose\nHubbard model with a modified coherent states path integral which can escribe -\nboth - phases. The saddle point theory yields collective oscillations of the\nuniform superfluid order parameter. These would be seen in time resolved\ninterference patterns made by the released gas. We calculate the collective\noscillation's damping rate by phason pair emission. In two dimensions the\noverdamped region largely overlaps with the quantum critical region.\nMeasurements of critical dynamics on the Mott side are proposed."
    },
    {
        "anchor": "Phase Behavior of a Family of Truncated Hard Cubes: In continuation of our work in [A.P. Gantapara et al., Phys. Rev. Lett. 111,\n015501 (2013)], we investigate here the thermodynamic phase behavior of a\nfamily of truncated hard cubes, for which the shape evolves smoothly from a\ncube via a cuboctahedron to an octahedron. We used Monte Carlo simulations and\nfree-energy calculations to establish the full phase diagram. This phase\ndiagram exhibits a remarkable richness in crystal and mesophase structures,\ndepending sensitively on the precise particle shape. In addition, we examined\nin detail the nature of the plastic crystal (rotator) phases that appear for\nintermediate densities and levels of truncation. Our results allow us to probe\nthe relation between phase behavior and building-block shape and to further the\nunderstanding of rotator phases. Furthermore, the phase diagram presented here\nshould prove instrumental for guiding future experimental studies on\nsimilarly-haped nanoparticles and the creation of new materials.",
        "positive": "The Role of Optical Projection in the Analysis of Membrane Fluctuations: We propose a methodology to measure the mechanical properties of membranes\nfrom their fluctuations and apply this to optical microscopy measurements of\ngiant unilamellar vesicles of lipids. We analyze the effect of the projection\nof thermal shape undulations across the focal depth of the microscope. We\nderive an analytical expression for the mode spectrum that varies with the\nfocal depth and accounts for the projection of fluctuations onto the equatorial\nplane. A comparison of our model with existing approaches, that use only the\napparent equatorial fluctuations without averaging out of this plane, reveals a\nsignificant and systematic reduction in the inferred value of the bending\nrigidity. Our results are in full agreement with the values measured through\nX-ray scattering and other micromechanical manipulation techniques, resolving a\nlong standing discrepancy with these other experimental methods."
    },
    {
        "anchor": "Electrophoresis of electrically neutral porous spheres induced by\n  selective affinity of ions: We investigate the possibility that electrically neutral porous spheres\nelectrophorese in electrolyte solutions with asymmetric affinity of ions to\nspheres on the basis of electrohydrodynamics and the Poisson-Boltzmann and\nDebye-Bueche-Brinkman theories. Assuming a weak electric field and ignoring the\ndouble-layer polarization, we obtain analytical expressions for electrostatic\npotential, electrophoretic mobility, and flow field. In the equilibrium state,\nthe Galvani potential forms across the interface of the spheres. Under a weak\nelectric field, the spheres show finite mobility with the same sign as the\nGalvani potential. When the radius of the spheres is significantly larger than\nthe Debye and hydrodynamic screening length, the mobility monotonically\nincreases with increasing salinity.",
        "positive": "An ubiquitous mechanism for waterlike anomalies: Using collision driven molecular dynamics a system of spherical particles\ninteracting through an effective two length scales potential is studied. The\npotential can be tuned by means of a single parameter, $\\lambda$, from a ramp\n$(\\lambda=0.5)$ to a square-shoulder potential $(\\lambda=1.0)$ representing a\nfamily of two length scales potential in which the shortest interaction\ndistance has higher potential energy than the largest interaction distance. For\nall the potentials, ranging between the ramp and the square-shoulder, density\nand structural anomalies were found, while the diffusion anomaly is found in\nall but in the square-shoulder potential. The presence anomalies in\nsquare-shoulder potential, not observed in previous simulations, confirm the\nassumption that the two length scales potential is an ubiquitous ingredient for\na system to exhibit water-like anomalies"
    },
    {
        "anchor": "Two State Behavior in a Solvable Model of $\u03b2$-hairpin folding: Understanding the mechanism of protein secondary structure formation is an\nessential part of protein-folding puzzle. Here we describe a simple model for\nthe formation of the $\\beta$-hairpin, motivated by the fact that folding of a\n$\\beta$-hairpin captures much of the basic physics of protein folding. We argue\nthat the coupling of ``primary'' backbone stiffness and ``secondary'' contact\nformation (similar to the coupling between the ``secondary'' and ``tertiary''\nstructure in globular proteins), caused for example by side-chain packing\nregularities, is responsible for producing an all-or-none 2-state\n$\\beta$-hairpin formation. We also develop a recursive relation to compute the\nphase diagram and single exponential folding/unfolding rate arising via a\ndominant transition state.",
        "positive": "Solvent-mediated interactions between nanostructures: from water to\n  Lennard-Jones liquid: Solvent-mediated interactions emerge from complex mechanisms that depend on\nthe solute structure, its wetting properties and the nature of the liquid.\nWhile numerous studies have focused on the two first influences, here, we\ncompare results from water and Lennard-Jones liquid in order to reveal to what\nextent solvent-mediated interactions are universal with respect to the nature\nof the liquid. Besides the influence of the liquid, results were obtained with\nclassical density functional theory and brute-force molecular dynamics\nsimulations which allows us to contrast these two numerical techniques."
    },
    {
        "anchor": "Colloid-colloid and colloid-wall interactions in driven suspensions: We investigate the non-equilibrium fluid structure mediated forces between\ntwo colloids driven through a suspension of mutually non-interacting Brownian\nparticles as well as between a colloid and a wall in stationary situations. We\nsolve the Smoluchowski equation in bispherical coordinates as well as with a\nmethod of reflections, both in linear approximation for small velocities and\nnumerically for intermediate velocities, and we compare the results to a\nsuperposition approximation considered previously. In particular we find an\nenhancement of the friction (compared to the friction on an isolated particle)\nfor two colloids driven side by side as well as for a colloid traveling along a\nwall. The friction on tailgating colloids is reduced. Colloids traveling side\nby side experience a solute induced repulsion while tailgating colloids are\nattracted to each other.",
        "positive": "Effects of Tunable Hydrophobicity on the Collective Hydrodynamics of\n  Janus Particles under Flows: Active colloidal systems with non-equilibrium self-organization is a\nlong-standing, challenging area in biology. To understand how hydrodynamic flow\nmay be used to actively control self-assembly of Janus particles (JPs), we use\na model recently developed for the many-body hydrodynamics of amphiphilic JPs\nsuspended in a viscous background flow (JFM, 941, 2022). We investigate how\nvarious morphologies arise from tuning the hydrophobic distribution of the\nJP-solvent interface. We find JPs assembled into uni-lamella, multi-lamella and\nstriated structures. To introduce dynamics, we include a linear shear flow and\na steady Taylor-Green mixing flow, and measure the collective dynamics of JP\nparticles in terms of their (a) free energy from the hydrophobic interactions\nbetween the JPs, (b) order parameter for the ordering of JPs in terms of\nalignment of their directors, and (c) strain parameter that captures the\ndeformation in the assembly. We characterize the effective material properties\nof the JP structures and find that the uni-lamellar structures increases\norientation order under shear flow, the multilamellar structure behaves as a\nshear thinning fluid, and the striated structure possesses a yield stress.\nThese numerical results provide insights into dynamic control of\nnon-equilibrium active biological systems with similar self-organization."
    },
    {
        "anchor": "Plastic flow and localization in an amorphous material: experimental\n  interpretation of the fluidity: We present a thorough study of the plastic response of a granular material\nprogressively loaded. We study experimentally the evolution of the plastic\nfield from a homogeneous one to an heterogeneous one and its fluctuations in\nterm of incremental strain. We show that the plastic field can be decomposed in\ntwo components evolving on two decoupled strain increment scales. We argue that\nthe slowly varying part of the field can be identified to the so-called\nfluidity field introduced recently to interpret the rheological behaviour of\namorphous materials. This fluidity field progressively concentrates along a\nmacroscopic direction corresponding to the Mohr-Coulomb angle.",
        "positive": "A model colloidal fluid with competing interactions: bulk and\n  interfacial properties: Using a simple mean-field density functional theory theory (DFT), we\ninvestigate the structure and phase behaviour of a model colloidal fluid\ncomposed of particles interacting via a pair potential which has a hard core of\ndiameter $\\sigma$, is attractive Yukawa at intermediate separations and\nrepulsive Yukawa at large separations. We analyse the form of the asymptotic\ndecay of the bulk fluid correlation functions, comparing results from our DFT\nwith those from the self consistent Ornstein-Zernike approximation (SCOZA). In\nboth theories we find rich crossover behaviour, whereby the ultimate decay of\ncorrelation functions changes from monotonic to long-wavelength damped\noscillatory decay on crossing certain lines in the phase diagram, or sometimes\nfrom oscillatory to oscillatory with a longer wavelength. For some choices of\npotential parameters we find, within the DFT, a $\\lambda$-line at which the\nfluid becomes unstable with respect to periodic density fluctuations. SCOZA\nfails to yield solutions for state points near such a $\\lambda$-line. The\npropensity to clustering of particles, which is reflected by the presence of a\nlong wavelength $\\gg \\sigma$, slowly decaying oscillatory pair correlation\nfunction, and a structure factor that exhibits a very sharp maximum at small\nbut non zero wavenumbers, is enhanced in states near the $\\lambda$-line. We\npresent density profiles for the planar liquid-gas interface and for fluids\nadsorbed at a planar hard wall. The presence of a nearby $\\lambda$-transition\ngives rise to pronounced long-wavelength oscillations in the one-body densities\nat both types of interface."
    },
    {
        "anchor": "Stochastic thermodynamics of a confined colloidal suspension under shear\n  flow: Based on Brownian dynamics simulations, we investigate the thermodynamic\nsignatures of non-equilibrium steady states in a confined colloidal suspensions\nunder shear flow. Specifically, we consider a thin film consisting of charged\nparticles in narrow slit-pore confinement, forming two layers with quadratic\nin-plane structure in equilibrium. This many-body system displays three\ndistinct steady states, characterized by unique dynamical and rheological\nresponse to the applied shear flow. Calculating the work and heat, we find that\nboth quantities indicate the different states by their mean and by their\ndistributions. A particularly interesting situation occurs at large shear\nrates, where the particles perform a collective zig-zag motion. Here, we find a\nbistability regarding the degree of phase synchronization of the particle\nmotion. It turns out that this bistability is key to understanding the\nresulting ensemble-averaged work distributions. For all states, we compare the\nwork and heat distributions to those of effective single-particle systems. By\nthis, we aim at identifying the many-body character of the stochastic\nthermodynamic quantities.",
        "positive": "Short chains at solid surfaces: wetting transition from a density\n  functional approach: A microscopic density functional theory is used to investigate the adsorption\nof short chains on attractive solid surfaces. We analyze the structure of the\nadsorbed fluid and investigate how the wetting transition changes with the\nchange of the chain length and with relative strength of the fluid-solid\ninteraction. End segments adsorb preferentially in the first adsorbed layer\nwhereas the concentration of the middle segments is enhanced in the second\nlayer. We observe that the wetting temperature rescaled by the bulk critical\ntemperature decreases with an increase of the chain length. For longer chains\nthis temperature reaches a plateau. For the surface critical temperature an\ninverse effect is observed, i.e. the surface critical temperature increases\nwith the chain length and then attains a plateau. These findings may serve as a\nquick estimate of the wetting and surface critical temperatures for fluids of\nlonger chain lengths."
    },
    {
        "anchor": "Defect Structures in the Growth Kinetics of the Swift-Hohenberg Model: The growth of striped order resulting from a quench of the two-dimensional\nSwift-Hohenberg model is studied in the regime of a small control parameter and\nquenches to zero temperature. We introduce an algorithm for finding and\nidentifying the disordering defects (dislocations, disclinations and grain\nboundaries) at a given time. We can track their trajectories separately. We\nfind that the coarsening of the defects and lowering of the effective free\nenergy in the system are governed by a growth law $L(t)\\approx t^{x}$ with an\nexponent x near 1/3. We obtain scaling for the correlations of the nematic\norder parameter with the same growth law. The scaling for the order parameter\nstructure factor is governed, as found by others, by a growth law with an\nexponent smaller than x and near to 1/4. By comparing two systems with\ndifferent sizes, we clarify the finite size effect. We find that the system has\na very low density of disclinations compared to that for dislocations and\nfraction of points in grain boundaries. We also measure the speed distributions\nof the defects at different times and find that they all have power-law tails\nand the average speed decreases as a power law.",
        "positive": "Shapes of hydrophobic thick membranes: We introduce and study the behavior of a tethered membrane of non-zero\nthickness embedded in three dimensions subject to an effective self-attraction\ninduced by hydrophobicity arising from the tendency to minimize the area\nexposed to a solvent. The phase behavior and the nature of the folded\nconformations are found to be quite distinct in the small and large solvent\nsize regimes. We demonstrate spontaneous symmetry-breaking with the membrane\nfolding along a preferential axis, when the solvent molecules are small\ncompared to the membrane thickness. For large solvent molecule size, a local\ncrinkling mechanism effectively shields the membrane from the solvent, even in\nrelatively flat conformations. We discuss the binding/unbinding transition of a\nmembrane to a wall that serves to shield the membrane from the solvent."
    },
    {
        "anchor": "Fragmentation Statistics of Food Diced and Crushed Using a Food Mixer: The fragment-size distributions of raw carrot diced or crushed using a food\nmixer are studied experimentally. For the 5-mm-square raw carrot, the normal\ndistribution shows a characteristic feature of food fragmentation statistics.\nThis simple result indicates that most random errors contribute to\nfragment-size fluctuation. On the other hand, for the crushed raw carrot, the\ncumulative fragment size distribution follows the power law where the exponent\n$\\alpha \\simeq 1.62 > 1$. Furthermore, considering the cumulative fragment-size\ndistribution as a function of length for comparison with geomaterials, such as\nfault rocks, the exponent $D \\simeq 3.64$. Previous studies have shown that the\npower-law distribution observed in sequential fragmentation tends to have a\nlarge exponent value. As our experiment is also based on sequential\nfragmentation, the obtained large values of exponents $\\alpha$ and $D$ are\nconsistent with those obtained in previous studies on sequential fragmentation.\nOn the basis of previous studies and our observations, we discuss the effect of\nthe preferential fragmentation of particles as large as the mixer blades. We\nalso discuss the existence of a lower limit beyond which further fragmentation\nis difficult, resulting in a power-law distribution tendency for raw carrot\ncrushed with a food mixer.",
        "positive": "Full-field, quasi-3D hygroscopic characterization of paper inter-fiber\n  bonds: The state-of-the-art in paper mechanics calls for novel experimental data\ncovering the full-field hygro-expansion of inter-fiber bonds in paper, i.e.,\nthe 3D morphological changes and inter-fiber interactions. Therefore, a\nrecently developed full-field single fiber hygro-expansion measurement\nmethodology based on global digital height correlation is extended to\northogonally bonded inter-fiber bonds, to investigate their full-field quasi-3D\nhygroscopic behavior. A sample holder has been developed which enables the\nquasi-3D characterization of the initial geometry of individual inter-fiber\nbonds, including the fiber thickness and width along the length of the fibers\nas well as the degree of wrap around and contact area of the bond, which are\nvital for understanding the inter-fiber bond hygro-mechanics. Full-field\nhygroscopic testing revealed novel insights on the inter-fiber interactions:\n(i) the transverse hygro-expansion of each fiber strongly reduces when\napproaching the bonded area, due to the significantly lower longitudinal\nhygro-expansion of the other bonded fiber. (ii) The relatively large transverse\nstrain of one fiber stretches the other crossing fiber in its longitudinal\ndirection, thereby significantly contributing to the sheet scale\nhygro-expansion. (iii) Out-of-plane bending is observed in the bonded region\nwhich is driven by the significant difference in transverse and longitudinal\nhygro-expansion of, respectively, the top and bottom fiber constituting the\nbond. A bi-layer laminate model is derived to rationalize the bending\ndeformation and an adequate match is found with the experimental data. Under\nthe assumption of zero bending, which represents constrained inter-fiber bonds\ninside a paper sheet, the model is able to predict the contribution of the\ntransverse strain in the bonded regions to the sheet-scale hygro-expansion."
    },
    {
        "anchor": "Line-tension-induced scenario of heterogeneous nucleation on a spherical\n  substrate and in a spherical cavity: Line-tension-induced {scenario of heterogeneous nucleation} is studied for a\nlens-shaped nucleus with a finite contact angle nucleated on a spherical\nsubstrate and on the bottom of the wall of a spherical cavity. The effect of\nline tension on the free energy of a critical nucleus can be separated from the\nusual volume term. By comparing the free energy of a lens-shaped critical\nnucleus of a finite contact angle with that of a spherical nucleus, we find\nthat a spherical nucleus may have a lower free energy than a lens-shaped\nnucleus when the line tension is positive and large, which is similar to the\ndrying transition predicted by Widom [B. Widom, J. Phys. Chem. {\\bf 99} 2803\n(1995)]. Then, the homogeneous nucleation rather than the heterogeneous\nnucleation will be favorable. Similarly, the free energy of a lens-shaped\nnucleus becomes negative when the line tension is negative and large. Then, the\nbarrier-less nucleation with no thermal activation called athermal nucleation\nwill be realized.",
        "positive": "Effects of Flow on Measurements of Interactions in Colloidal Suspensions: A hydrodynamic mechanism of interactions of colloidal particles is\nconsidered. The mechanism is based on the assumption of tiny background flows\nin the experimental cells during measurements by Grier at al. [1-6]. Both\ntrivial (shear flow) and non-trivial (force propagation through viscous fluid)\neffects are taken into account for two colloidal particles near a wall bounding\nthe solvent. Expressions for the radial (attractive or repulsive) forces and\nthe polar torques are obtained. Quantitative estimates of the flow needed to\nproduce the observed strength of attractive force are given, other necessary\nconditions are also considered. The conclusion is made: the mechanism suggested\nmost likely is not responsible for the attractive interactions observed in the\nexperiments of Grier at al.; however, it may be applicable in other\nexperimental realizations and should be kept in mind while conducting colloidal\nmeasurements of high sensitivity. Several distinctive features of the\ninteractions due to this mechanism are identified."
    },
    {
        "anchor": "Theory of Crosslinked Bundles of Helical Filaments: Intrinsic Torques in\n  Self-Limiting Biopolymer Assemblies: Inspired by the complex influence of the globular crosslinking proteins on\nthe formation of biofilament bundles in living organisms, we study and analyze\na theoretical model for the structure and thermodynamics of bundles of helical\nfilaments assembled in the presence of crosslinking molecules. The helical\nstructure of filaments, a universal feature of biopolymers such as filamentous\nactin, is shown to generically frustrate the geometry of crosslinking between\nthe \"grooves\" of two neighboring filaments. We develop a coarse-grained model\nto investigate the interplay between the geometry of binding and mechanics of\nboth linker and filament distortion, and we show that crosslinking in parallel\nbundles of helical filaments generates {\\it intrinsic torques}, of the type\nthat tend to wind bundle superhelically about its central axis. Crosslinking\nmediates a non-linear competition between the preference for bundle twist and\nthe size-dependent mechanical cost of filament bending, which in turn gives\nrise to feedback between the global twist of self-assembled bundles and their\nlateral size. Finally, we demonstrate that above a critical density of bound\ncrosslinkers, twisted bundles form with a thermodynamically preferred radius\nthat, in turn, increases with a further increase in crosslinking bonds. We\nidentify the {\\it stiffness} of crosslinking bonds as a key parameter governing\nthe sensitivity of bundle structure and assembly to the availability and\naffinity of crosslinkers.",
        "positive": "Smectic Layering: Landau theory for a complex-tensor order parameter: Composed of microscopic layers that stack along one direction while\nmaintaining fluid-like positional disorder within layers, smectics are\nexcellent systems for exploring topology, defects and geometric memory in\ncomplex confining geometries. However, the coexistence of crystalline-like\ncharacteristics in one direction and fluid-like disorder within layers makes\nlamellar liquid crystals notoriously difficult to model - especially in the\npresence of defects and large distortions. Nematic properties of smectics can\nbe comprehensively described by the Q-tensor but to capture the features of the\nsmectic layering alone, we develop a phenomenological Landau theory for a\ncomplex-tensor order parameter E, which is capable of describing the local\ndegree of lamellar ordering, layer displacement, and orientation of the layers.\nThis theory can account for both parallel and perpendicular elastic\ncontributions. In addition to resolving the potential ambiguities inherent to\ncomplex scalar order parameter models, this model reduces to previous employed\nmodels of simple smectics, and opens new possibilities for numerical studies on\nsmectics possessing many defects, within complex geometries and under extreme\nconfinement."
    },
    {
        "anchor": "Capillary Levelling of Immiscible Bilayer Films: Flow in thin films is highly dependent on the boundary conditions. Here, we\nstudy the capillary levelling of thin bilayer films composed of two immiscible\nliquids. Specifically, a stepped polymer layer is placed atop another, flat\npolymer layer. The Laplace pressure gradient resulting from the curvature of\nthe step induces flow in both layers, which dissipates the excess capillary\nenergy stored in the stepped interface. The effect of different viscosity\nratios between the bottom and top layers is investigated. We invoke a long-wave\nexpansion of low-Reynolds-number hydrodynamics to model the energy dissipation\ndue to the coupled viscous flows in the two layers. Good agreement is found\nbetween the experiments and the model. Analysis of the latter further reveals\nan interesting double crossover in time, from Poiseuille flow, to plug flow,\nand finally to Couette flow. The crossover time scales depend on the viscosity\nratio between the two liquids, allowing for the dissipation mechanisms to be\nselected and finely tuned by varying this ratio.",
        "positive": "Thermal gas rectification using a sawtooth channel: We study the rectification of a two-dimensional thermal gas in a channel of\nasymmetric dissipative walls. For an ensemble of smooth Lennard-Jones\nparticles, our numerical simulations reveal a non-monotonic dependence of the\nflux on the thermostat temperature, channel asymmetry, and particle density,\nwith three distinct regimes. Theoretical arguments are developed to shed light\non the functional dependence of the flux on the model parameters."
    },
    {
        "anchor": "Disordered Hyperuniform Heterogeneous Materials: Disordered hyperuniform many-body systems are distinguishable states of\nmatter that lie between a crystal and liquid: they are like perfect crystals in\nthe way they suppress large-scale density fluctuations and yet are like liquids\nor glasses in that they are statistically isotropic with no Bragg peaks. These\nsystems play a vital role in a number of fundamental and applied problems:\nglass formation, jamming, rigidity, photonic and electronic band structure,\nlocalization of waves and excitations, self-organization, fluid dynamics,\nquantum systems, and pure mathematics. systems. Here, we derive new rigorous\ncriteria that disordered hyperuniform two-phase heterogeneous materials must\nobey and explore their consequences. Two-phase heterogeneous media are\nubiquitous, examples include composites and porous media, biological media,\nfoams, polymer blends, granular media, cellular solids, and colloids. We\nrigorously establish the requirements for sphere packings to be\n\"multihyperuniform.\" We apply realizability conditions for an autocovariance\nfunction and its associated spectral density of a two-phase medium, and then\nincorporate hyperuniformity as a constraint in order to derive new conditions.\nWe show that some functional forms can immediately be eliminated from\nconsideration and identify other forms that are allowable. Specific examples\nand counterexamples are described. Contact is made with well-known\nmicrostructural models as well as irregular phase-separation and Turing-type\npatterns. We also ascertain a family of spectral densities that are realizable\nby disordered hyperuniform two-phase media in any space dimension, and present\nexplicit constructions. These studies provide insight into the nature of\ndisordered hyperuniformity in the context of heterogeneous materials and have\nimplications for the design of such novel amorphous materials.",
        "positive": "Surface alignment disorder and pseudo-Casimir forces in smectic-A liquid\n  crystalline films: Random (disordered) components in the surface anchoring of the smectic-A\nliquid crystalline film in general modify the thermal pseudo-Casimir\ninteraction. Anchoring disorder of the quenched type is in general decoupled\nfrom the thermal pseudo-Casimir force and gives rise to an additional\ndisorder-generated interaction, in distinction to the annealed disorder, whose\neffect on the pseudo-Casimir force is non-additive. We consider the effects of\nthe surface anchoring disorder by assuming that one of the substrates of the\nfilm is contaminated by a disorder source, resulting in a Gaussian-weighted\ndistribution of the preferred molecular anchoring orientation (easy axes) on\nthat substrate, having a finite mean and variance or, more generally, a\nhomogeneous in-plane, two-point correlation function. We show that the presence\nof disorder, either of the quenched or annealed type, leads to a significant\nreduction in the magnitude of the net thermal fluctuation force between the\nconfining substrates of the film. In the quenched case this is a direct\nconsequence of an additive free energy dependent on the variance of the\ndisorder, while in the annealed case, the suppression of the interaction force\ncan be understood based on a disorder-renormalized, effective anchoring\nstrength."
    },
    {
        "anchor": "A two-species continuum model for aeolian sand transport: Starting from the physics on the grain scale, we develop a simple continuum\ndescription of aeolian sand transport. Beyond popular mean-field models, but\nwithout sacrificing their computational efficiency, it accounts for both\ndominant grain populations, hopping (or \"saltating\") and creeping (or\n\"reptating\") grains. The predicted stationary sand transport rate is in\nexcellent agreement with wind tunnel experiments simulating wind conditions\nranging from the onset of saltation to storms. Our closed set of equations thus\nprovides an analytically tractable, numerically precise, and computationally\nefficient starting point for applications addressing a wealth of phenomena from\ndune formation to dust emission.",
        "positive": "Frank elasticity of composite colloidal nematics with anti-nematic order: Mixing colloid shapes with distinctly different anisotropy generates\ncomposite nematics in which the order of the individual components can be\nfundamentally different. In colloidal rod-disk mixtures or hybrid nematics\ncomposed of anisotropic colloids immersed in a thermotropic liquid crystal, one\nof the components may adopt so-called anti-nematic order while the other\nexhibits conventional nematic alignment. Focussing on simple models for hard\nrods and disks, we employ Onsager-Straley's second-virial theory to derive\nscaling expressions for the elastic moduli of rods and disks in both nematic\nand anti-nematic configurations and identify their explicit dependence on\nparticle concentration and shape. We demonstrate that the splay, bend and twist\nelasticity of anti-nematically ordered particles scale logarithmically with the\ndegree of anti-nematic order, with the bend-splay ratio for anti-nematic\ndiscotic nematics being far greater than for conventional nematic systems. The\nimpact of surface anchoring on the elastic properties of hybrid nematics will\nalso be discussed in detail. We further demonstrate that the elasticity of\nmixed uniaxial rod-disk nematics depends exquisitely on the shape of the\ncomponents and we provide simple scaling expressions that could help engineer\nthe elastic properties of composite nematic liquid crystals."
    },
    {
        "anchor": "Stochastic effects on solution landscapes for nematic liquid crystals: We study the effects of additive and multiplicative noise on the solution\nlandscape of nematic liquid crystals confined to a square domain within the\nLandau-de Gennes framework, as well as the impact of additive noise on the\nsymmetric radial hedgehog solution for nematic droplets. The introduction of\nrandom noise can be used to capture material uncertainties and imperfections,\nwhich are always present in physical systems. We implement random noise in our\nframework by introducing a Q-Wiener stochastic process to the governing\ndifferential equations. On the square, the solution landscape for the\ndeterministic problem is well understood, enabling us to compare and contrast\nthe deterministic predictions and the stochastic predictions, while we\ndemonstrate that the symmetry of the radial hedgehog solution can be violated\nby noise. This approach of introducing noise to deterministic equations can be\nused to test the robustness and validity of predictions from deterministic\nliquid crystal models, which essentially capture idealised situations.",
        "positive": "Thermoresponsivity of poly(N-isopropylacrylamide) microgels in\n  water-trehalose solution and its relation to protein behavior: Hypotheses: Additives are commonly used to tune macromolecular conformational\ntransitions. Among additives, trehalose is an excellent bioprotectant and among\nresponsive polymers, PNIPAM is the most studied material. Nevertheless, their\ninteraction mechanism so far has only been hinted without direct investigation,\nand, crucially, never elucidated in comparison to proteins. Detailed insights\nwould help understand to what extent PNIPAM microgels can effectively be used\nas synthetic biomimetic materials, to reproduce and study, at the colloidal\nscale, isolated protein behavior and its sensitivity to interactions with\nspecific cosolvents or cosolutes. Experiments: The effect of trehalose on the\nswelling behavior of PNIPAM microgels was monitored by dynamic light\nscattering; Raman spectroscopy and molecular dynamics simulations were used to\nexplore changes of solvation and dynamics across the swelling-deswelling\ntransition at the molecular scale. Findings: Strongly hydrated trehalose\nmolecules develop water-mediated interactions with PNIPAM microgels, thereby\npreserving polymer hydration below and above the transition while drastically\ninhibiting local motions of the polymer and of its hydration shell. Our study,\nfor the first time, demonstrates that slowdown of dynamics and preferential\nexclusion are the principal mechanisms governing trehalose effect on PNIPAM\nmicrogels, at odds with preferential adsorption of alcohols, but in full\nanalogy with the behavior observed in trehalose-protein systems."
    },
    {
        "anchor": "The role of polymer architecture in the entropy driven segregation and\n  spatial organization of bacterial chromosomes: Entropic repulsion between DNA ring polymers under confinement is the key\nmechanism governing the spatial segregation of bacterial chromosomes, although\nit remains incompletely understood how proteins aid the process of entropic\nsegregation. Here we establish that `internal' loops within a modified-ring\npolymer architecture enhances entropic repulsion between two overlapping\npolymers confined in a cylinder. Moreover it also induces entropy-driven\nspatial organization of polymer segments as seen in-vivo. To that end, we\ndesign polymers of different architectures in our simulations, by introducing a\nminimal number of cross-links between particular monomers along the chain\ncontour. This helps us to identify the underlying mechanisms which lead to\nfaster segregation of spatially overlapping polymers as well as localization of\nspecific polymer segments. The observed segregation dynamics of overlapping\npolymers is aided in our simulations by the frequent release of topological\nconstraints, implemented by allowing chains to cross each at regular intervals.\nAdditionally, we compare the segregation dynamics timescales with that of\nself-avoiding polymers and thereby highlight the significance of Topoisomerase\nin biological systems where DNA-strands are allowed to occasionally pass\nthrough each other. We use the blob model to provide a theoretical\nunderstanding of why or how certain architectures lead to enhanced entropic\nrepulsive forces between loops, which in turn leads to the positional\norganization of segments relative to each other in confined environments.\nLastly, we establish a correspondence between the C.crescentus bacterial\nspecies and our results for one particular polymer architecture.",
        "positive": "Simulation of microswimmer hydrodynamics with multiparticle collision\n  dynamics: In this review we discuss the recent progress in the simulation of soft\nactive matter systems and in particular the hydrodynamics of microswimmers\nusing the method of multiparticle collision dynamics, which solves the\nhydrodynamic flows around active objects on a coarse-grained level. We first\npresent a brief overview of the basic simulation method and the coupling\nbetween microswimmers and fluid. We then review the current achievements in\nsimulating flexible and rigid microswimmers using multiparticle collision\ndynamics, and briefly conclude and discuss possible future directions."
    },
    {
        "anchor": "Event-Driven Dynamics of Rigid Bodies Interacting via Discretized\n  Potentials: A framework for performing event-driven, adaptive time step simulations of\nsystems of rigid bodies interacting under stepped or terraced potentials in\nwhich the potential energy is only allowed to have discrete values is outlined.\nThe scheme is based on a discretization of an underlying continuous potential\nthat effectively determines the times at which interaction energies change. As\nin most event-driven approaches, the method consists of specifying a means of\ncomputing the free motion, evaluating the times at which interactions occur,\nand determining the consequences of interactions on subsequent motion for the\nterraced-potential. The latter two aspects are shown to be simply expressible\nin terms of the underlying smooth potential. Within this context, algorithms\nfor computing the times of interaction events and carrying out efficient\nevent-driven simulations are discussed. The method is illustrated on system\ncomposed of rigid rods in which the constituents interact via a terraced\npotential that depends on the relative orientations of the rods.",
        "positive": "Soft materials for linear electromechanical energy conversion: We briefly review the literature of linear electromechanical effects of soft\nmaterials, especially in synthetic and biological polymers and liquid crystals\n(LCs). First we describe results on direct and converse piezoelectricity, and\nthen we discuss a linear coupling between bending and electric polarization,\nwhich maybe called bending piezoelectricity, or flexoelectricity."
    },
    {
        "anchor": "Absolutely necessary to consider the caged dynamics and the JGX\n  $\u03b2$-relaxation in solving the glass transition problem: The 2003 seminal paper entitled \"Is the Fragility of a Liquid Embedded in the\nProperties of Its Glass?\" by Tullio Scopigno, Giancarlo Ruocco, Francesco\nSette, and Giulio Monaco, reported that the properties of the structural\n$\\alpha$-relaxation of glass-formers are already present in the faster caged\ndynamics. Their important discovery has far-reaching implication of the\nprocesses faster than the structural $\\alpha$-relaxation that cannot be ignored\nin solving the glass transition problem. Since then, experiments and\nsimulations performed on many glass-formers with diverse chemical and physical\nstructures have found strong connections of the $\\alpha$-relaxation with not\nonly the caged dynamics but also with the secondary relaxation of the special\nkind, called the JGX $\\beta$-relaxation. The general results indicate that\nthese fast processes are inseparable from the $\\alpha$-relaxation, and any\nattempt to solve the glass transition problem should take account of this fact.\nExamples of the connections are given in this paper to elucidate the\ndevelopments and advances made since the inspiring publication of Scopigno et\nal.",
        "positive": "The Physics of the Colloidal Glass Transition: As one increases the concentration of a colloidal suspension, the system\nexhibits a dramatic increase in viscosity. Structurally, the system resembles a\nliquid, yet motions within the suspension are slow enough that it can be\nconsidered essentially frozen. This kinetic arrest is the colloidal glass\ntransition. For several decades, colloids have served as a valuable model\nsystem for understanding the glass transition in molecular systems. The spatial\nand temporal scales involved allow these systems to be studied by a wide\nvariety of experimental techniques. The focus of this review is the current\nstate of understanding of the colloidal glass transition. A brief introduction\nis given to important experimental techniques used to study the glass\ntransition in colloids. We describe features of colloidal systems near and in\nglassy states, including tremendous increases in viscosity and relaxation\ntimes, dynamical heterogeneity, and ageing, among others. We also compare and\ncontrast the glass transition in colloids to that in molecular liquids. Other\nglassy systems are briefly discussed, as well as recently developed synthesis\ntechniques that will keep these systems rich with interesting physics for years\nto come."
    },
    {
        "anchor": "Phase-separation in ion-containing mixtures in electric fields: When a liquid mixture is subjected to external electric fields, ionic\nscreening leads to field gradients. We point out that if the mixture is\ninitially in the homogeneous phase, this screening can bring about a robust\nphase-separation transition with two main features: (i) the phase separation is\nexpected to occur in any electrode geometry, and (ii) the voltage required is\ntypically of the order of 1 V and even less. We discuss several applications of\nthe effect relevant to the field of microfluidics, focusing on the creation of\na nanometer-scale lubrication layer in the phase-separation process.",
        "positive": "Crossover Scales at the Critical Points of Fluids with Electrostatic\n  Interactions: Criticality in a fluid of dielectric constant D that exhibits Ising-type\nbehavior is studied as additional electrostatic (i.e., ionic) interactions are\nturned on. An exploratory perturbative calculation is performed for small\nionicity as measured by the ratio of the electrostatic energy to the strength\nof the short-range nonionic (i.e., van der Waals) interactions in the uncharged\nfluid.\n  With the aid of distinct transformations for the short-range and for the\nCoulombic interactions, an effective Hamiltonian with coefficients depending on\nthe ionicity is derived at the Debye-Hueckel limiting-law level for a fully\nsymmetric model. The crossover between classical (mean-field) and Ising\nbehavior is then estimated using a Ginzburg criterion. This indicates that the\nreduced crossover temperature depends only weakly on the ionicity (and on the\nrange of the nonionic potentials); however, the trends do correlate with the,\nmuch stronger, dependence observed experimentally."
    },
    {
        "anchor": "Peristaltic elastic instability in an inflated cylindrical channel: A long cylindrical cavity through a soft solid forms a soft microfluidic\nchannel, or models a vascular capillary. We observe experimentally that, when\nsuch a channel bears a pressurized fluid, it first dilates homogeneously, but\nthen becomes unstable to a peristaltic elastic instability. We combine theory\nand numerics to fully characterize the instability in a channel through a bulk\nneo-Hookean solid, showing that instability occurs supercritically with\nwavelength $2\\pi/k=12.278....a$ when the pressure exceeds $2.052....\\mu$. In\nfinite solids, the threshold pressure is reduced, and peristalsis is followed\nby a second instability which shears the peristaltic shape breaking\naxisymmetry. These instabilities shows that, counterintuitively, if a pipe runs\nthrough a bulk solid, the bulk solid can be destabilizing rather than\nstabilizing at high pressures. They also offers a route to fabricate\nperiodically undulating channels, producing waveguides with photonic/phononic\nstop bands.",
        "positive": "Finite size and inner structure controlled by electrostatic screening in\n  globular complexes of proteins and polyelectrolytes: We present an extended structural study of globular complexes made by mixing\na positively charge protein (lysozyme) and a negatively charged polyelectrolyte\n(PSS). We study the influence of all the parameters that may act on the\nstructure of the complexes (charge densities and concentration of the species,\npartial hydrophobicity of the polyion chain, ionic strength). The structures on\na 15 scale range lying from 10{\\AA} to 1000{\\AA} are measured by SANS. Whatever\nthe conditions, the same structure is found, based on the formation of dense\nglobules of ~ 100{\\AA} with a neutral core and a volume fraction of organic\nspecies (compacity) of ~ 0.3. At higher scale, the globules are arranged in\nfractal aggregates. Zetametry measurements show that globular complexes have a\ntotal positive charge when the charge ratio of species introduced in the\nmixture [-]/[+]intro > 1 and a total 20 negative charge when [-]/[+]intro < 1.\nThis comes from the presence of charged species in slight excess in a layer at\nthe surface of the globules. The globule finite size is determined by the Debye\nlength k-1 whatever the way the physicochemical parameters are modified in the\nsystem, as long as chain-protein interactions are of simple electrostatics\nnature. The mean number of proteins per primary complex Nlyso_comp grows\nexponentially on a master curve with k-1. This enables to picture 25 the\nmechanisms of formation of the complexes. There is an initial stage of\nformation where the growth of the complexes is only driven by attractions\nbetween opposite species associated with counterion release. During the growth\nof the complexes, the globules progressively repell themselves by electrostatic\nrepulsion because their charge increases. When this repulsion becomes dominent\nin the system, globules stop growing and behave like charged colloids: they\naggregate 30 with a RLCA process, which leads to the formation of fractal\naggregates of dimension Df 2.1."
    },
    {
        "anchor": "Phase diagram of two-patch colloids with competing anisotropic and\n  isotropic interactions: Patchy particles are considered to be a good model for protein aggregation.\nWe calculate the equilibrium phase diagram of two-patch colloidal particles\nundergoing aggregation along with isotropic potential. This investigation\ndemonstrates the coexistence of different phases like disordered clusters,\nchains, crystals and bundles depending on the relative strength of isotropic\nand anisotropic potential, these phases are also reported for glucose isomerase\nproteins. We also show that the formation of network of bundles is metastable\nagainst the formation of thermodynamically favored finite sized bundles, which\nare also metastable along with thermodynamically stable crystals. These bundles\nappear to be helical in structure similar to that observed in sickle cell\nhemoglobin.",
        "positive": "Wire active microrheology to differentiate viscoelastic liquids from\n  soft solids: Viscoelastic liquids are characterized by a finite static viscosity and a\nzero yield stress, whereas soft solids have an infinite viscosity and a\nnon-zero yield stress. The rheological nature of viscoelastic materials has\nlong been a challenge, and it is still a matter of debate. Here, we provide for\nthe first time the constitutive equations of linear viscoelasticity for\nmagnetic wires in yield stress materials, together with experimental\nmeasurements using Magnetic Rotational Spectroscopy (MRS). With MRS, the wires\nare submitted to a rotational magnetic field as a function of frequency and the\nwire motion is monitored by time-lapse microscopy. The soft solids studied are\ngel-forming polysaccharide aqueous dispersions (gellan gum) at concentrations\nabove the gelification point. It is found that soft solids exhibit a clear and\ndistinctive signature compared to viscous and viscoelastic liquids. In\nparticular, the wire average rotation velocity equals zero over a broad\nfrequency range. We also show the MRS technique is quantitative. From the wire\noscillation amplitudes, the equilibrium elastic modulus is retrieved and agrees\nwith polymer dynamics theory."
    },
    {
        "anchor": "Dancing Volvox: Hydrodynamic Bound States of Swimming Algae: The spherical alga Volvox swims by means of flagella on thousands of surface\nsomatic cells. This geometry and its large size make it a model organism for\nstudying the fluid dynamics of multicellularity. Remarkably, when two nearby\nVolvox swim close to a solid surface, they attract one another and can form\nstable bound states in which they \"waltz\" or \"minuet\" around each other. A\nsurface-mediated hydrodynamic attraction combined with lubrication forces\nbetween spinning, bottom-heavy Volvox explains the formation, stability and\ndynamics of the bound states. These phenomena are suggested to underlie\nobserved clustering of Volvox at surfaces.",
        "positive": "Nonequilibrium dynamics of mixtures of active and passive colloidal\n  particles: We develop a mesoscopic field theory for the collective nonequilibrium\ndynamics of multicomponent mixtures of interacting active (i.e., motile) and\npassive (i.e., nonmotile) colloidal particles with isometric shape in two\nspatial dimensions. By a stability analysis of the field theory, we obtain\nequations for the spinodal that describes the onset of a motility-induced\ninstability leading to cluster formation in such mixtures. The prediction for\nthe spinodal is found to be in good agreement with particle-resolved computer\nsimulations. Furthermore, we show that in active-passive mixtures the spinodal\ninstability can be of two different types. One type is associated with a\nstationary bifurcation and occurs also in one-component active systems, whereas\nthe other type is associated with a Hopf bifurcation and can occur only in\nactive-passive mixtures. Remarkably, the Hopf bifurcation leads to moving\nclusters. This explains recent results from simulations of active-passive\nparticle mixtures, where moving clusters and interfaces that are not seen in\nthe corresponding one-component systems have been observed."
    },
    {
        "anchor": "Depletion interaction between two ellipsoids: The depletion interactions between two ellipsoids in three configurations\nwere studied by both Monte Carlo simulation with the Wang-Landau algorithm and\nthe density functional theory in the curvature expansion approximation. Common\nfeatures of the depletion interactions were found and the results were as\nexpected. By comparing the results of the two methods, it is concluded that\ndensity functional theory under the curvature expansion approximation gave very\ngood results to the depletion forces.",
        "positive": "Self-regulation in Self-Propelled Nematic Fluids: We consider the hydrodynamic theory of an active fluid of self-propelled\nparticles with nematic aligning interactions. This class of materials has polar\nsymmetry at the microscopic level, but forms macrostates of nematic symmetry.\nWe highlight three key features of the dynamics. First, as in polar active\nfluids, the control parameter for the order-disorder transition, namely the\ndensity, is dynamically convected by active currents, resulting in a generic,\nmodel independent dynamical self-regulation that destabilizes the uniform\nnematic state near the mean-field transition. Secondly, curvature driven\ncurrents render the system unstable deep in the nematic state, as found\npreviously. Finally, and unique to self-propelled nematics, nematic order\ninduces local polar order that in turn leads to the growth of density\nfluctuations. We propose this as a possible mechanism for the smectic order of\npolar clusters seen in numerical simulations."
    },
    {
        "anchor": "Comment on \"Kosterlitz-Thouless-type caging-uncaging transition in a\n  quasi-one-dimensional hard disk system\" [Phys. Rev. Research 2, 033351\n  (2020)]: Huerta et al. [Phys. Rev. Research 2, 033351 (2020)] report a power-law decay\nof positional order in numerical simulations of hard disks confined within hard\nparallel walls, which they interpret as a Kosterlitz-Thouless-type\ncaging-uncaging transition. The proposed existence of such a transition in a\nquasi-one-dimensional (q1D) system, however, contradicts long-held physical\nexpectations. To clarify if the proposed ordering persists in the thermodynamic\nlimit, we introduce an exact transfer matrix approach to expeditiously generate\nequilibrium configurations for systems of arbitrary size. The power-law decay\nof positional order is found to extend only over finite distances. We conclude\nthat the numerical simulation results reported are associated with a crossover,\nand not a proper thermodynamic phase transition.",
        "positive": "Highly porous layers of silica nano-spheres sintered by drying: Scaling\n  up of the elastic properties from the beads to the macroscopic mechanical\n  properties: Layers obtained by drying a colloidal dispersion of silica spheres are found\nto be a good benchmark to test the elastic behaviour of porous media, in the\nchallenging case of high porosities and nano-sized microstructures. Classically\nused for these systems, Kendall's approach explicitely considers the effect of\nsurface adhesive forces onto the contact area between the particles. This\napproach provides the Young's modulus using a single adjustable parameter (the\nadhesion energy) but provides no further information on the tensorial nature\nand possible anisotropy of elasticity. On the other hand, homogenization\napproaches (e.g. rule of mixtures, Eshelby, Mori-Tanaka and self-consistent\nschemes), based on continuum mechanics and asymptotic analysis, provide the\nstiffness tensor from the knowledge of the porosity and the elastic constants\nof the beads. Herein, the self-consistent scheme accurately predicts both bulk\nand shear moduli, with no adjustable parameter, provided the porosity is less\nthan 35%, for layers composed of particles as small as 15 nm in diameter.\nConversely, Kendall's approach is found to predict the Young's modulus over the\nfull porosity range. Moreover, the adhesion energy in Kendall's model has to be\nadjusted to a value of the order of the fracture energy of the particle\nmaterial. This suggests that sintering during drying leads to the formation of\ncovalent siloxane bonds between the particles."
    },
    {
        "anchor": "Understanding Legged Crawling for Soft-Robotics: Crawling is a common locomotion mechanism in soft robots and nonskeletal\nanimals. In this work we propose modeling soft-robotic legged locomotion by\napproximating it with an equivalent articulated robot with elastic joints. For\nconcreteness we study our soft robot with two bending actuators via an\narticulated three-link model. The solution of statically indeterminate systems\nwith stick-slip contact transitions requires for a novel hybrid-quasitatic\nanalysis. Then, we utilize our analysis to investigate the influence of\nphase-shifted harmonic inputs on performance of crawling gaits, including\nsensitivity analysis to friction uncertainties and energetic cost of transport.\nWe achieve optimal values of gait parameters. Finally, we fabricate and test a\nfluid-driven soft robot. The experiments display remarkable agreement with the\ntheoretical analysis, proving that our simple model correctly captures and\nexplains the fundamental principles of inchworm crawling and can be applied to\nother soft-robotic legged robots.",
        "positive": "Significantly enhanced polymer thermal conductivity by confining effect\n  through bilayer MoS2 Surfaces: The present work refers to a simulation study on nanoconfined polymers in\npolymer-MoS 2 nanocomposites as a function of MoS 2 -MoS 2 interlayer\nseparation. We indeed apply reverse nonequlibrium molecular dynamics\nsimulations (RNEMD) to investigate thermal conductivity of polyamide oligomers\nwhich is confined by MoS 2 bilayers. The polymer thermal conductivity can be\nconsiderably enhanced when polymer chains are confined by MoS 2 sheets, in\nparticular such behavior is more obvious for charged surfaces. The presence of\nthe MoS 2 surfaces leads to well- ordering of polymer chains as well as denser\npacking which is an increase in {\\lambda} in the polymer network via the use of\nMoS 2 surface confinement. Polymer chains elongation as well as their\npreferential alignment parallel to the MoS 2 surfaces indicates that {\\lambda}\nin the polymer domain of the considered nanocomposites is larger than the one\nin the pure polymer phase. Additionally, our results of number of hydrogen\nbonds (HBs) in confined polymer chains suggest that a combined effect of the\nmentioned structural modification and enlarged values of HBs may cooperatively\ncontribute to high polymer thermal conductivity facilitating phonon transport.\nResults reported here suggest a significant manner to design of confined\npolymer-MoS 2 composites for a wide variety range of applications."
    },
    {
        "anchor": "The Dukhin number as a scaling parameter for selectivity in the\n  infinitely long nanopore limit: extension to multivalent electrolytes: Scaling of the behavior of a nanodevice means that the device function\n(selectivity, in this work) is a unique function of a scaling parameter that is\nan appropriate combination of the device parameters. Although nanopores\nfacilitate the transport of ions through a membrane of finite length if the\npore is long compared to the pore radius, we deal with an important limiting\ncase, the infinitely long nanopore (nanotube). While in our previous study\n(Sarkadi et al., J. Chem. Phys. 154 (2021) 154704.) we showed that the Dukhin\nnumber is an appropriate scaling parameter in the nanotube limit for 1:1\nelectrolytes, in this work we obtain the Dukhin number from first principles on\nthe basis of the Poisson-Boltzmann (PB) theory and generalize it to\nelectrolytes containing multivalent ions as well. We show that grand canonical\nMonte Carlo simulations for charged hard spheres in an implicit solvent give\nresults that are similar to those obtained from the PB theory with deviations\nthat are the consequences of ionic correlations (including finite size of ions)\nbeyond the mean-field level of the PB theory. Such a deviation occurs when\ncharge inversion is present, in 2:2 and 3:1 electrolytes, for example.",
        "positive": "Anisotropy of force distributions in sheared soft particle systems: In this numerical study, measurements of the contact forces inside a periodic\ntwo-dimensional sheared system of soft frictional particles are reported. The\ndistribution of normalized normal forces exhibits a gradual broadening with\nincreasing the pure shear deformation, leading to a slower decay for large\nforces. The process however slows down and the distribution approaches an\ninvariant shape at high shear deformations. By introducing the joint\nprobability distribution in sheared configurations, it is shown that for a\nfixed direction, the force distribution decays faster than exponentially even\nin a sheared system. The overall broadening can be attributed to the averaging\nover different directions in the presence of shear-induced stress anisotropy.\nThe distribution of normalized tangential forces almost preserves its shape for\narbitrary applied strain."
    },
    {
        "anchor": "Finding the Differences: Classical Nucleation Perspective on Homogeneous\n  Melting and Freezing of Hard Spheres: By employing brute-force molecular dynamics, umbrella sampling, and seeding\nsimulations, we investigate homogeneous nucleation during melting and freezing\nof hard spheres. We provide insights into these opposing phase transitions from\nthe standpoint of classical nucleation theory. We observe that melting has both\na lower driving force and a lower interfacial tension than freezing. The lower\ndriving force arises from the vicinity of a spinodal instability in the solid\nand from a strain energy. The lower interfacial tension implies that the Tolman\nlengths associated with melting and freezing have opposite signs, a phenomenon\nthat we interpret with Turnbull's rule. Despite these asymmetries, the\nnucleation rates for freezing and melting are found to be comparable.",
        "positive": "Self healing slip pulses along a gel/glass interface: We present an experimental evidence of self-healing shear cracks at a\ngel/glass interface. This system exhibits two dynamical regimes depending on\nthe driving velocity : steady sliding at high velocity (> Vc = 100-125 \\mu\nm/s), caracterized by a shear-thinning rheology, and periodic stick-slip\ndynamics at low velocity. In this last regime, slip occurs by propagation of\npulses that restick via a ``healing instability'' occuring when the local\nsliding velocity reaches the macroscopic transition velocity Vc. At driving\nvelocities close below Vc, the system exhibits complex spatio-temporal\nbehavior."
    },
    {
        "anchor": "Effect of Polydispersity and Anisotropy in Colloidal and Protein\n  Solutions: an Integral Equation Approach: Application of integral equation theory to complex fluids is reviewed, with\nparticular emphasis to the effects of polydispersity and anisotropy on their\nstructural and thermodynamic properties. Both analytical and numerical\nsolutions of integral equations are discussed within the context of a set of\nminimal potential models that have been widely used in the literature. While\nother popular theoretical tools, such as numerical simulations and density\nfunctional theory, are superior for quantitative and accurate predictions, we\nargue that integral equation theory still provides, as in simple fluids, an\ninvaluable technique that is able to capture the main essential features of a\ncomplex system, at a much lower computational cost. In addition, it can provide\na detailed description of the angular dependence in arbitrary frame, unlike\nnumerical simulations where this information is frequently hampered by\ninsufficient statistics. Applications to colloidal mixtures, globular proteins\nand patchy colloids are discussed, within a unified framework.",
        "positive": "BCS Theory for Trapped Ultracold Fermions: We develop an extension of the well-known BCS-theory to systems with trapped\nfermions. The theory fully includes the quantized energy levels in the trap.\nThe key ingredient is to model the attractive interaction between two atoms by\na pseudo-potential which leads to a well defined scattering problem and\nconsequently a BCS-theory free of divergences. We present numerical results for\nthe BCS critical temperature and the temperature dependence of the gap. They\nare used as a test of existing semi-classical approximations."
    },
    {
        "anchor": "Effective Wall Friction in Wall-Bounded 3D Dense Granular Flows: We report numerical simulations on granular shear flows confined between two\nflat but frictional sidewalls. Novel regimes differing by their strain\nlocalization features are observed. They originate from the competition between\ndissipation at the sidewalls and dissipation in the bulk of the flow. The\neffective friction at sidewalls is characterized (effective friction\ncoefficient and orientation of the friction force) for each regime, and its\ninterdependence with slip and force fluctuations is pointed out. We propose a\nsimple scaling law linking the slip velocity to the granular temperature in the\nmain flow direction which leads naturally to another scaling law for the\neffective friction.",
        "positive": "Colloidal Deposit of an Evaporating Sessile Droplet on a Non-uniformly\n  Heated Substrate: The pattern and profile of a dried colloidal deposit formed after evaporation\nof a sessile water droplet containing polystyrene particles on a non-uniformly\nheated glass are investigated experimentally. In particular, the effects of\ntemperature gradient across the substrate and particles size are investigated.\nThe temperature gradient was imposed using Peltier coolers, and side\nvisualization, infrared thermography, optical microscopy, and optical\nprofilometry were employed to collect the data. On a uniformly heated\nsubstrate, a ring with an inner deposit is obtained, which is attributed to\naxisymmetric Marangoni recirculation and consistent with previous reports.\nHowever, the dimensions of the ring formed on a non-uniformly heated substrate\nare significantly different on the hot and cold side of the substrate and are\nfound to be a function of the temperature gradient and particles size. In the\ncase of smaller particle size, the contact line on hot side depins and together\nwith twin asymmetric Marangoni recirculations, it results in a larger ring\nwidth on the cold side as compared to the hot side. In contrast, the contact\nline remains pinned in case of larger particles, and the twin asymmetric\nMarangoni recirculations advect more particles on the hot side, resulting in a\nlarger ring width at the hot side. A mechanistic model is employed to explain\nwhy the depinning is dependent on the particle size. A larger temperature\ngradient significantly increases or decreases the ring width depending on the\nparticle size, due to a stronger intensity recirculation. A regime map is\nproposed for the deposit patterns on temperature gradient-particle size plane\nto classify the deposits."
    },
    {
        "anchor": "Stick-slip phenomena and Schallamach waves captured using reversible\n  cohesive elements: Reversibility is of paramount importance in the correct representation of\nsurface peeling in various physical settings, ranging from motility in nature,\nto gripping devices in robotic applications, and even to sliding of tectonic\nplates. Modeling the detachment-reattachment sequence, known as stick-slip,\nimposes several challenges in a continuum framework. Here we exploit customized\nreversible cohesive elements in a hybrid finite element model that can handle\noccurrence of snap-through instabilities. The simulations capture various\npeeling phenomena that emerge in experimental observations, where layers are\npulled from a flat, rigid substrate in the direction parallel to the surface.\nFor long layers, periodicity in reattachment is shown to develop and is linked\nto the concept of Schallamach waves. Further, the connection between surface\nproperties and stick-slip behavior is investigated: we find that stick-slip is\nlinked to the propensity of the interface to localize deformation and damage.\nBeyond elucidating the various peeling behaviors and the detachment modes, the\ncomputational framework developed here provides a straightforward approach for\ninvestigation of complex delamination processes, which can guide development of\nfuture applications across different scales and in various settings.",
        "positive": "Scaling of dynamics with the range of interaction in short-range\n  attractive colloids: We numerically study the dependence of the dynamics on the range of\ninteraction $\\Delta$ for the short-range square well potential. We find that,\nfor small $\\Delta$, dynamics scale exactly in the same way as thermodynamics,\nboth for Newtonian and Brownian microscopic dynamics. For interaction ranges\nfrom a few percent down to the Baxter limit, the relative location of the\nattractive glass line and the liquid-gas line does not depend on $\\Delta$. This\nproves that in this class of potentials, disordered arrested states (gels) can\nbe generated only as a result of a kinetically arrested phase separation."
    },
    {
        "anchor": "Softening of the stiffness of bottlebrush polymers by mutual interaction: We study bottlebrush macromolecules in a good solvent by small-angle neutron\nscattering (SANS), static light scattering (SLS), and dynamic light scattering\n(DLS). These polymers consist of a linear backbone to which long side chains\nare chemically grafted. The backbone contains about 1600 monomer units (weight\naverage) and every second monomer unit carries side-chains with ca. 60 monomer\nunits. The SLS- and SANS data extrapolated to infinite dilution lead to the\nform factor of the polymer that can be described in terms of a worm-like chain\nwith a contour length of 380 nm and a persistence length of 17.5 nm. An\nanalysis of the DLS data confirm these model parameters. The scattering\nintensities taken at finite concentration can be modeled using the polymer\nreference interaction site model. It reveals a softening of the bottlebrush\npolymers caused by their mutual interaction. We demonstrate that the\npersistence decreases from 17.5 nm down to 5 nm upon increasing the\nconcentration from dilute solution to the highest concentration 40.59 g/l under\nconsideration. The observed softening of the chains is comparable to the\ntheoretically predicted decrease of the electrostatic persistence length of\nlinear polyelectrolyte chains at finite concentrations.",
        "positive": "Designing biodegradable surfactants and effective biomolecules with\n  dissipative particle dynamics: The design of a biodegradable, environmentally friendly surfactant is carried\nout, taking the structure of a known surfactant that lacks these qualities as\nthe starting point, using mesoscopic computer simulations. The newly designed\nsurfactant is found to perform at least as well as its predecessor, without the\nlatter inimical characteristics. In the second part of this work, a comparative\nstudy of model proteins with different amino acid sequence interacting with\nsurfaces is undertaken. The results show that, all other aspects being equal,\nthis sequence is the key factor determining the optimal activity of the\nproteins near surfaces. These conclusions are found to be in agreement with\nrecent experiments from the literature."
    },
    {
        "anchor": "Stabilization of multiple emulsions using natural surfactants: In an emulsion system, emulsifier is one of the most important substances as\nit determines the formation, stability and physicochemical properties of\nemulsions. In this study, the effects of emulsifier concentration, type of\nhydrophilic emulsifier, as well as portions of primary emulsion (weight) on the\nstability of W/O/W emulsions were investigated. Microscopy images of W/O/W\nemulsions indicated that the emulsions prepared with 0.5 gram of sodium\ncaseinate have superior stability over other synthesis conditions. Finally,\nemulsions were prepared using different types of emulsifier (NaCN, Cremophor,\nTween 60). Our results showed that emulsions made form Cremophor and Tween 60\nin comparison with sodium caseinate possess smaller droplets size with enhanced\nstability.",
        "positive": "Calculation of Spectra of the Lattice and Surface Vibrations of Organic\n  Nano-Crystals: Calculations of frequencies of the lattice and surface oscillations of\norganic nano-crystals are carried out. As the sample the para-dichlorobenzol\nhas been chosen. Change of spectra of oscillations from the sizes of\nnano-particles is found. It is shown that with the reduction of the sizes of\nnano-particles a spectrum of the surface oscillations prevailing. Calculations\nhave shown that for the correct interpretation of the observational spectra it\nis necessary to consider orientation disorder of the surface molecules and\npresence of vacancies in nano-particle volume."
    },
    {
        "anchor": "Crossover Time in Relative Fluctuations Characterizes the Longest\n  Relaxation Time of Entangled Polymers: In entangled polymer systems, there are several characteristic time scales,\nsuch as the entanglement time and the disengagement time. In molecular\nsimulations, the longest relaxation time (the disengagement time) can be\ndetermined by the mean square displacement (MSD) of a segment or by the shear\nrelaxation modulus. Here, we propose the relative fluctuation analysis method,\nwhich is originally developed for characterizing large fluctuations, to\ndetermine the longest relaxation time from the center of mass trajectories of\npolymer chains (the time-averaged MSDs). Applying the method to simulation data\nof entangled polymers (by the slip-spring model and the simple reptation\nmodel), we provide a clear evidence that the longest relaxation time is\nestimated as the crossover time in the relative fluctuations.",
        "positive": "Particles inside Electrolytes with Ion-specific Interactions, Their\n  Effective Charge Distributions and Effective Interactions: In this work, we explore the statistical physics of colloidal particles that\ninteract with electrolytes via ion-specific interactions. Firstly we study\nparticles interact weakly with electrolyte using linear response theory. We\nfind that the mean potential around a particle is linearly determined by the\n{\\em effective charge distribution} of the particle, which depends both on the\nbare charge distribution and on ion-specific interactions. We also discuss the\neffective interaction between two such particles and show that, in far field\nregime, it is bilinear in the effective charge distributions of two particles.\nWe subsequently generalize the above results to the more complicated case where\nparticles interact strongly with the electrolyte. Our results indicate that in\norder to understand the statistical physics of non-dilute electrolytes, both\nion-specific interactions and ionic correlations have to be addressed in a\nsingle unified and consistent framework."
    },
    {
        "anchor": "A Stability Diagram for Dense Suspensions of Model Colloidal\n  Al2O3-Particles in Shear Flow: In Al2O3 suspensions, depending on the experimental conditions very different\nmicrostructures can be found, comprising fluid like suspensions, a repulsive\nstructure, and a clustered microstructure. For technical processing in\nceramics, the knowledge of the microstructure is of importance, since it\nessentially determines the stability of a workpiece to be produced. To\nenlighten this topic, we investigate these suspensions under shear by means of\nsimulations. We observe cluster formation on two different length scales: the\ndistance of nearest neighbors and on the length scale of the system size. We\nfind that the clustering behavior does not depend on the length scale of\nobservation. If inter-particle interactions are not attractive the particles\nform layers in the shear flow. The results are summarized in a stability\ndiagram.",
        "positive": "Smoothed Dissipative Particle Dynamics model for mesoscopic multiphase\n  flows in the presence of thermal fluctuations: Thermal fluctuations cause perturbations of fluid-fluid interfaces and highly\nnonlinear hydrodynamics in multiphase flows. In this work, we develop a novel\nmultiphase smoothed dissipative particle dynamics model. This model accounts\nfor both bulk hydrodynamics and interfacial fluctuations. Interfacial surface\ntension is modeled by imposing a pairwise force between SDPD particles. We show\nthat the relationship between the model parameters and surface tension,\npreviously derived under the assumption of zero thermal fluctuation, is\naccurate for fluid systems at low temperature but overestimates the surface\ntension for intermediate and large thermal fluctuations. To analyze the effect\nof thermal fluctuations on surface tension, we construct a coarse-grained Euler\nlattice model based on the mean field theory and derive a semi-analytical\nformula to directly relate the surface tension to model parameters for a wide\nrange of temperatures and model resolutions. We demonstrate that the present\nmethod correctly models the dynamic processes, such as bubble coalescence and\ncapillary spectra across the interface."
    },
    {
        "anchor": "Segregation by friction: Granular materials are known to separate by size under a variety of\ncircumstances. Experiments presented here and elucidated by modeling and MD\nsimulation document a new segregation mechanism, namely segregation by\nfriction. The experiments are carried out by placing steel spheres on a\nhorizontal plane enclosed by rectangular sidewalls, and subjecting them to\nhorizontal shaking. Half the spheres are highly smooth; the remainder are\nidentical to the first half, except that their surfaces have been roughened by\nchemical etching, giving them higher coefficients of friction. Segregation due\nto this difference in friction occurs, particularly when the grains have a\nrelatively long mean free path. In the presence of an appropriately chosen\nsmall ``hill'' in the middle of the container, the grains can be made to\ncompletely segregate by friction type.",
        "positive": "The hidden topological structure of flow network functionality: The ability to reroute and control flow is vital to the function of venation\nnetworks across a wide range of organisms. By modifying individual edges in\nthese networks, either by adjusting edge conductances or creating and\ndestroying edges, organisms can robustly control the propagation of inputs to\nperform specific tasks. However, a fundamental disconnect exists between the\nstructure and function of these networks: networks with different local\narchitectures can perform the same functions. Here we answer the question of\nhow structural changes at the microscopic level are able to collectively create\nfunctionality at the scale of an entire network. Using persistent homology, we\nanalyze networks tuned to perform complex multifunctional tasks. We find that\nthe responses of such networks encode a hidden topological structure composed\nof sectors of uniform pressure. Although these sectors are not apparent in the\nunderlying network architectures, we find that they nonetheless correlate\nstrongly with the tuned function. We conclude that the connectivity of these\nsectors, rather than that of the individual nodes, provides a quantitative\nrelationship between structure and function in flow networks. Finally, we use\nthis topological description to place a bound on the limits of task complexity."
    },
    {
        "anchor": "Velocity correlations in dense granular gases: We report the statistical properties of spherical steel particles rolling on\nan inclined surface being driven by an oscillating wall. Strong dissipation\noccurs due to collisions between the particles and rolling and can be tuned by\nchanging the number density. The velocities of the particles are observed to be\ncorrelated over large distances comparable to the system size. The distribution\nof velocities deviates strongly from a Gaussian. The degree of the deviation,\nas measured by the kurtosis of the distribution, is observed to be as much as\nfour times the value corresponding to a Gaussian, signaling a significant\nbreakdown of the assumption of negligible velocity correlations in a granular\nsystem.",
        "positive": "Phase behavior of mixtures of hard ellipses: A scaled particle density\n  functional study: We present a scaled particle density functional study of two-dimensional\nbinary mixtures of hard convex particles with one or both species being\nellipses. In particular, we divide our study into two parts. The first part is\ndevoted to the calculation of phase diagrams of mixtures with the same\nelliptical shapes, but with (i) different aspect ratios and equal particle\nareas, (ii) equal aspect ratios and different particle areas and (iii) with the\nformer and the later being different. In the second study we obtain the phase\ndiagrams corresponding to crossed-mixtures of particles with species having\nelliptical and rectangular shapes. We compare the phase diagram topologies and\nexplain their main features from the entropic nature of particle interactions\ndirectly related to the anisotropies, areas, and shapes of species. The results\nobtained can be corroborated by experiments on granular rods where the entropic\nforces are very important in the stabilization of liquid-crystal textures at\nthe stationary states."
    },
    {
        "anchor": "The rise and fall of branching: a slowing down mechanism in relaxing\n  wormlike micellar networks: A mean-field kinetic model suggests that the relaxation dynamics of wormlike\nmicellar networks is a long and complex process due to the problem of reducing\nthe number of free end-caps (or dangling ends) while also reaching an\nequilibrium level of branching after an earlier overgrowth. The model is\nvalidated against mesoscopic molecular dynamics simulations and is based on\nkinetic equations accounting for scission and synthesis processes of blobs of\nsurfactants. A long relaxation time scale is reached both with thermal quenches\nand small perturbations of the system. The scaling of this relaxation time is\nexponential with the free energy of an end cap and with the branching free\nenergy. We argue that the subtle end-recombination dynamics might yield effects\nthat are difficult to detect in rheology experiments, with possible\nunderestimates of the typical time scales of viscoelastic fluids.",
        "positive": "Electrostatics of quadrupolarizable media: The classical macroscopic Maxwell equations are approximated. They are a\ncorollary of the multipole expansion of the local electrostatic potential up to\ndipolar terms. But quadrupolarization of the medium should not be neglected if\nthe molecules which build up the medium possess large quadrupole moment or do\nnot have any dipole moment. If we include the quadrupolar terms in Maxwell\nequations we obtain the quadrupolar analogue of Poisson's equation: $\\nabla^2\n\\phi - L^2_Q\\nabla^4 \\phi = - \\rho / \\varepsilon$. This equation is of the\nfourth order and it requires not only the two classical boundary conditions but\nalso two additional ones: continuous electric field and the relation of the\njump of the normal quadrupolarizability at the surface to the intrinsic normal\nsurface dipole moment. The account of the quadrupole moment of the molecules\nleads to significant differences compared to the classical electrostatic\ntheory."
    },
    {
        "anchor": "A Study of Snake-like Locomotion Through the Analysis of a Flexible\n  Robot Model: We examine the problem of snake-like locomotion by studying a system\nconsisting of a planar inextensible elastic rod that is able to control its\nspontaneous curvature. Using a Cosserat model we derive, through variational\nprinciples, the equations of motion for two special cases: one in which the\nsystem is confined inside a frictionless channel, and one in which it is placed\nin an anisotropic frictional environment, modeling the dynamical setting of the\nslithering of snakes on flat surfaces. The presence of constraints in both\ncases leads to non-standard boundary conditions, that allow us to close the\nequations of motion reducing them to a differential and an integro-differential\nequation, respectively, for one end point (the tail) of the active rod. For the\nsnake-like case we also provide analytic solutions for a special class of\nmotions. We highlight the role of the spontaneous curvature in the pushing (and\nthe steering, in the snake-like setting) needed to power locomotion.\nComparisons with available experiments confirm that the model is able to\ncapture many of the essential findings in the zoological literature. The\ncomplete solvability and the existence of analytic solutions offers a tool that\nmay prove valuable for the design of bio-inspired soft robots.",
        "positive": "Influence of cap weight on the motion of a Janus particle very near a\n  wall: The dynamics of anisotropic nano- to microscale colloidal particles in\nconfined environments, either near neighboring particles or boundaries, is\nrelevant to a wide range of applications. We utilized Brownian dynamics\nsimulations to predict the translational and rotational fluctuations of a Janus\nsphere with a cap of non-matching density. The presence of the cap\nsignificantly impacted the rotational dynamics of the particle as a consequence\nof gravitational torque at experimentally relevant conditions. Gravitational\ntorque dominated stochastic torque for a particle > 1 micrometer in diameter\nand with a 20 nm thick gold cap. Janus particles at these conditions sampled\nmostly cap-down or quenched orientations. Although the results summarized\nherein showed that particles of smaller diameter (< 1 micrometer) with a thin\ngold coating (< 5 nm) behave similar to an isotropic particle, small increases\nin either particle diameter or coating thickness drastically quenched the polar\nrotation of the particle. Histogram landscapes of the separation distance from\nthe boundary and orientation observations of particles with larger diameters or\nthicker gold coatings were mostly populated with quenched configurations.\nFinally, the histogram landscapes were inverted to obtain the potential energy\nlandscapes, providing a path for experimental data to be interpreted."
    },
    {
        "anchor": "Yielding and hardening of flexible fiber packings during triaxial\n  compression: This paper examines the mechanical response of flexible fiber packings\nsubject to triaxial compression. Short fibers yield in a manner similar to\ntypical granular materials in which the deviatoric stress remains nearly\nconstant with increasing strain after reaching a peak value. Interestingly,\nlong fibers exhibit a hardening behavior, where the stress increases rapidly\nwith increasing strain at large strains and the packing density continuously\nincreases. Phase diagrams for classifying the bulk mechanical response as\nyielding, hardening, or a transition regime are generated as a function of the\nfiber aspect ratio, fiber-fiber friction coefficient, and confining pressure.\nLarge fiber aspect ratio, large fiber-fiber friction coefficient, and large\nconfining pressure promote hardening behavior. The hardening packings can\nsupport much larger loads than the yielding packings contributing to the\nstability and consolidation of the granular structure, but larger internal\naxial forces occur within fibers.",
        "positive": "Shear Unzipping of DNA: We study theoretically the mechanical failure of a simple model of double\nstranded DNA under an applied shear. Starting from a more microscopic\nHamiltonian that describes a sheared DNA, we arrive at a nonlinear\ngeneralization of a ladder model of shear unzipping proposed earlier by\ndeGennes [deGennes P. G. C. R. Acad. Sci., Ser. IV; Phys., Astrophys. 2001,\n1505]. Using this model and a combination of analytical and numerical methods,\nwe study the DNA \"unzipping\" transition when the shearing force exceeds a\ncritical threshold at zero temperature. We also explore the effects of sequence\nheterogeneity and finite temperature and discuss possible applications to\ndetermine the strength of colloidal nanoparticle assemblies functionalized by\nDNA."
    },
    {
        "anchor": "Langevin dynamics simulations of biomolecules on graphics processors: Due to the very long timescales involved (us-s), theoretical modeling of\nfundamental biological processes including folding, misfolding, and mechanical\nunraveling of biomolecules, under physiologically relevant conditions, is\nchallenging even for distributed computing systems. Graphics Processing Units\n(GPUs) are emerging as an alternative programming platform to the more\ntraditional CPUs as they provide high raw computational power that can be\nutilized in a wide range of scientific applications. Using a coarse-grained\nSelf Organized Polymer (SOP) model, we have developed and tested the GPU-based\nimplementation of Langevin simulations for proteins (SOP-GPU program).\nSimultaneous calculation of forces for all particles is implemented using\neither the particle based or the interacting pair based parallelization, which\nleads to a ~30-fold acceleration compared to an optimized CPU version of the\nprogram. We assess the computational performance of an end-to-end application\nof the SOP-GPU program, where all steps of the algorithm are running on the\nGPU, by profiling the associated simulation time and memory usage for a number\nof small proteins, long protein fibers, and large-size protein assemblies. The\nSOP-GPU package can now be used in the theoretical exploration of the\nmechanical properties of large-size protein systems to generate the\nforce-extension and force-indentation profiles under the experimental\nconditions of force application, and to relate the results of single-molecule\nexperiments in vitro and in silico.",
        "positive": "Structure and dynamics of DOPC vesicles: A transformation from\n  unilamellar to multilamellar vesicles by n-alkyl-PEO polymer: We investigate the influence of a non-ionic surfactant like polymer on\nphospholipid vesicles. Our results from cryogenic transmission electron\nmicroscopy (cryo-TEM), dynamic light scattering (DLS), small angle neutron and\nX-ray scattering (SANS/SAXS), identifies the existence of multilayer vesicles\nand an increase in size of the vesicles in presence of the polymers. We present\na generalized model to obtain the bending rigidity from neutron spin echo\nspectroscopy (NSE) data for multilayer vesicles. We demonstrated that polymers\nare trapped in the lipid bilayer, causing a partial disruption in the vesicle,\nwhich is attributed to the reduction in bending rigidity per unit bilayer. We\nalso observed substantial dampening of the trapped lipid tail motion in\npresence of the polymer. Our results highlighted the possibilities of using\nspecialized polymers that can disrupt membrane and control their dynamics with\npossible application in topical drug or nutraceutical formulations."
    },
    {
        "anchor": "Characteristics of the Johari-Goldstein process in rigid asymmetric\n  molecules: Molecular dynamics simulations were carried out on a Lennard-Jones binary\nmixture of rigid (fixed bond length) diatomic molecules. The translational and\nrotational correlation functions, and the corresponding susceptibilities,\nexhibit two relaxation processes, the slow structural relaxation (alpha\ndynamics) and a higher frequency secondary relaxation. The latter is a\nJohari-Goldstein (JG) process, by its definition of involving all parts of the\nmolecule. It shows several properties characteristic of the JG process - (i)\nmerging with the alpha relaxation at high temperature; (ii) a change in\ntemperature-dependence of the relaxation strength on vitrification; (iii) a\nseparation in frequency from the alpha relaxation that correlates with the\nbreadth of the structural dispersion; and (iv) sensitivity to volume, pressure,\nand physical aging - that can be used to determine whether a secondary\nrelaxation in a real material is an authentic JG process, rather than trivial\nmotion involving intramolecular degrees of freedom. The latter has no\nconnection to the glass transition, whereas the JG relaxation is closely\nrelated to structural relaxation, and thus can provide new insights into the\nphenomenon.",
        "positive": "Marginally compact fractal trees with semiflexibility: We study marginally compact macromolecular trees that are created by means of\ntwo different fractal generators. In doing so, we assume Gaussian statistics\nfor the vectors connecting nodes of the trees. Moreover, we introduce bond-bond\ncorrelations that make the trees locally semiflexible. The symmetry of the\nstructures allows an iterative construction of full sets of eigenmodes\n(notwithstanding the additional interactions that are present due to\nsemiflexibility constraints), enabling us to get physical insights about the\ntrees' behavior and to consider larger structures. Due to the local stiffness\nthe self-contact density gets drastically reduced."
    },
    {
        "anchor": "How Geometry Controls the Tearing of Adhesive Thin Films on Curved\n  Surfaces: Flaps can be detached from a thin film glued on a solid substrate by tearing\nand peeling. For flat substrates, it has been shown that these flaps\nspontaneously narrow and collapse in pointy triangular shapes. Here we show\nthat various shapes, triangular, elliptic, acuminate or spatulate, can be\nobserved for the tears by adjusting the curvature of the substrate. From\ncombined experiments and theoretical models, we show that the flap morphology\nis governed by simple geometric rules.",
        "positive": "Thermal softening during high-temperature torsional deformation of\n  aluminum bars: A simple extension of the thermodynamic dislocation theory to non-uniform\nplastic deformations is proposed for an analysis of high-temperature torsion of\naluminum bars. Employing a small set of physics-based parameters, which we\nexpect to be approximately independent of strain rate and temperature, we are\nable to fit experimental torque-twist curves for five different twist rates and\nat one fixed ambient temperature. We find that thermal softening due to\ntemperature rise is significant at high twist rates."
    },
    {
        "anchor": "Particle flow rate in silos under rotational shear: Very recently, To et al.~have experimentally explored granular flow in a\ncylindrical silo, with a bottom wall that rotates horizontally with respect to\nthe lateral wall \\cite{Kiwing2019}. Here, we numerically reproduce their\nexperimental findings, in particular, the peculiar behavior of the mass flow\nrate $Q$ as a function of the frequency of rotation $f$. Namely, we find that\nfor small outlet diameters $D$ the flow rate increased with $f$, while for\nlarger $D$ a non-monotonic behavior is confirmed. Furthermore, using a\ncoarse-graining technique, we compute the macroscopic density, momentum, and\nthe stress tensor fields. These results show conclusively that changes in the\ndischarge process are directly related to changes in the flow pattern from\nfunnel flow to mass flow. Moreover, by decomposing the mass flux (linear\nmomentum field) at the orifice into two main factors: macroscopic velocity and\ndensity fields, we obtain that the non-monotonic behavior of the linear\nmomentum is caused by density changes rather than by changes in the macroscopic\nvelocity. In addition, by analyzing the spatial distribution of the kinetic\nstress, we find that for small orifices increasing rotational shear enhances\nthe mean kinetic pressure $\\langle p^k \\rangle$ and the system dilatancy. This\nreduces the stability of the arches, and, consequently, the volumetric flow\nrate increases monotonically. For large orifices, however, we detected that\n$\\langle p^k \\rangle$ changes non-monotonically, which might explain the\nnon-monotonic behavior of $Q$ when varying the rotational shear.",
        "positive": "Laboratory X-ray Study of the Phospholipid Monolayers at the Water\n  Surface: The possibility of laboratory X-ray reflectometry study of the structure of\ndimyristoyl phosphatidylserine (DMPS) phospholipid monolayers on the water\nsurface in various phase states has been demonstrated."
    },
    {
        "anchor": "Dynamic synchrotron X-ray imaging study of effective temperature in a\n  vibrated granular medium: We present a dynamic synchrotron X-ray imaging study of the effective\ntemperature $T_{eff}$ in a vibrated granular medium. By tracking the directed\nmotion and the fluctuation dynamics of the tracers inside, we obtained\n$T_{eff}$ of the system using Einstein relation. We found that as the system\nunjams with increasing vibration intensities $\\Gamma$, the structural\nrelaxation time $\\tau$ increases substantially which can be fitted by an\nArrhenius law using $T_{eff}$. And the characteristic energy scale of\nstructural relaxation yielded by the Arrhenius fitting is $E = 0.21 \\pm 0.02$\n$pd^3$, where $p$ is the pressure and $d$ is the background particle diameter,\nwhich is consistent with those from hard sphere simulations in which the\nstructural relaxation happens via the opening up of free volume against\npressure.",
        "positive": "Rotational correlation and dynamic heterogeneity in a kinetically\n  constrained lattice gas: We study dynamical heterogeneity and glassy dynamics in a kinetically\nconstrained lattice gas model which has both translational and rotational\ndegrees of freedom. We find that the rotational diffusion constant tracks the\nstructural relaxation time as density is increased whereas the translational\ndiffusion constant exhibits a strong decoupling. We investigate distributions\nof exchange and persistence times for both the rotational and translational\ndegrees of freedom and compare our results on the distributions of rotational\nexchange times to recent single molecule studies."
    },
    {
        "anchor": "Surface free energies for nematic shells: We propose a continuum model to describe the molecular alignment in thin\nnematic shells. By contrast with previous accounts, the two-dimensional free\nenergy, aimed at describing the physics of thin films of nematics deposited on\ncurved substrates, is not postulated but it is deduced from the conventional\nthree-dimensional theories of nematic liquid crystals. Both the director and\nthe order-tensor theories are taken into account. The so-obtained surface\nenergies exhibit extra terms compared to earlier models. These terms reflect\nthe coupling of the geometry of the shell with the nematic order parameters. As\nexpected, the shape of the shell plays a key role in the equilibrium\nconfigurations of nematics coating it.",
        "positive": "Virtual bending method to calculate bending rigidity, saddle-splay\n  modulus, and spontaneous curvature of thin fluid membrane: A method to calculate the bending rigidity $\\kappa$, saddle-splay modulus\n$\\bar{\\kappa}$, and spontaneous curvature $C_0$ of a fluid membrane is\nproposed. Virtual work for the bending deformations into cylindrical and\nspherical shapes is calculated for a flat membrane. This method does not\nrequire a force decomposition, unlike the existing stress-profile method. The\nfirst derivative of the deformation gives $\\kappa C_0$ and is a discrete form\nof the first moment of the stress profile. The second derivatives give $\\kappa$\nand $\\bar{\\kappa}$, and include the variance terms of the first derivatives,\nwhich are not accounted for in the stress-profile method. This method is\nexamined for a solvent-free meshless membrane model and a\ndissipative-particle-dynamics two-bead amphiphilic molecular model. It is\nconcluded that $\\kappa$ and $\\bar{\\kappa}$ of a thin membrane can be accurately\ncalculated, whereas for a thick membrane or one with an explicit solvent, a\nfurther extension to include the volume-fluctuation effects is required for an\naccurate estimation. The amplitude of the volume-fluctuation effects can be\nevaluated using the parameter dependence in the present method."
    },
    {
        "anchor": "Molecular Motors Interacting with Their Own Tracks: Dynamics of molecular motors that move along linear lattices and interact\nwith them via reversible destruction of specific lattice bonds is investigated\ntheoretically by analyzing exactly solvable discrete-state ``burnt-bridge''\nmodels. Molecular motors are viewed as diffusing particles that can\nasymmetrically break or rebuild periodically distributed weak links when\npassing over them. Our explicit calculations of dynamic properties show that\ncoupling the transport of the unbiased molecular motor with the bridge-burning\nmechanism leads to a directed motion that lowers fluctuations and produces a\ndynamic transition in the limit of low concentration of weak links. Interaction\nbetween the backward biased molecular motor and the bridge-burning mechanism\nyields a complex dynamic behavior. For the reversible dissociation the backward\nmotion of the molecular motor is slowed down. There is a change in the\ndirection of the molecular motor's motion for some range of parameters. The\nmolecular motor also experiences non-monotonic fluctuations due to the action\nof two opposing mechanisms: the reduced activity after the burned sites and\nlocking of large fluctuations. Large spatial fluctuations are observed when two\nmechanisms are comparable. The properties of the molecular motor are different\nfor the irreversible burning of bridges where the velocity and fluctuations are\nsuppressed for some concentration range, and the dynamic transition is also\nobserved. Dynamics of the system is discussed in terms of the effective driving\nforces and transitions between different diffusional regimes.",
        "positive": "Tunable morphing of electroactive dielectric-elastomer balloons: Designing smart devices with tunable shapes has important applications in\nindustrial manufacture. In this paper, we investigate the nonlinear deformation\nand the morphological transitions between buckling, necking, and snap-through\ninstabilities of layered DE balloons in response to an applied radial voltage\nand an inner pressure. We propose a general mathematical theory of nonlinear\nelectro-elasticity able to account for finite inhomogeneous strains provoked by\nthe electro-mechanical coupling. We investigate the onsets of morphological\ntransitions of the spherically symmetric balloons using the surface impedance\nmatrix method. Moreover, we study the nonlinear evolution of the bifurcated\nbranches through finite element numerical simulations. Our analysis\ndemonstrates the possibility to design tunable DE spheres, where the onset of\nbuckling and necking can be controlled by geometrical and mechanical properties\nof the passive elastic layers. Relevant applications include soft robotics and\nmechanical actuators."
    },
    {
        "anchor": "Statistics of level spacing of geometric resonances in random binary\n  composites: We study the statistics of level spacing of geometric resonances in the\ndisordered binary networks. For a definite concentration $p$ within the\ninterval $[0.2,0.7]$, numerical calculations indicate that the unfolded level\nspacing distribution $P(t)$ and level number variance $\\Sigma^2(L)$ have the\ngeneral features. It is also shown that the short-range fluctuation $P(t)$ and\nlong-range spectral correlation $\\Sigma^2(L)$ lie between the profiles of the\nPoisson ensemble and Gaussion orthogonal ensemble (GOE). At the percolation\nthreshold $p_c$, crossover behavior of functions $P(t)$ and $% \\Sigma^2(L)$ is\nobtained, giving the finite size scaling of mean level spacing $\\delta$ and\nmean level number $n$, which obey the scaling laws, $% \\delta=1.032 L ^{-1.952}\n$ and $n=0.911L^{1.970}$.",
        "positive": "Fast Fitting of Reflectivity Data of Growing Thin Films Using Neural\n  Networks: X-ray reflectivity (XRR) is a powerful and popular scattering technique that\ncan give valuable insight into the growth behavior of thin films. In this\nstudy, we show how a simple artificial neural network model can be used to\npredict the thickness, roughness and density of thin films of different organic\nsemiconductors (diindenoperylene, copper(II) phthalocyanine and\n$\\alpha$-sexithiophene) on silica from their XRR data with millisecond\ncomputation time and with minimal user input or a priori knowledge. For a large\nexperimental dataset of 372 XRR curves, we show that a simple fully connected\nmodel can already provide good predictions with a mean absolute percentage\nerror of 8-18 % when compared to the results obtained by a genetic least mean\nsquares fit using the classical Parratt formalism. Furthermore, current\ndrawbacks and prospects for improvement are discussed."
    },
    {
        "anchor": "Structure of liquid--vapor interfaces: perspectives from liquid state\n  theory, large-scale simulations, and potential grazing-incidence X-ray\n  diffraction: Grazing-incidence X-ray diffraction (GIXRD) is a scattering technique which\nallows one to characterize the structure of fluid interfaces down to the\nmolecular scale, including the measurement of the surface tension and of the\ninterface roughness. However, the corresponding standard data analysis at\nnon-zero wave numbers has been criticized as to be inconclusive because the\nscattering intensity is polluted by the unavoidable scattering from the bulk.\nHere we overcome this ambiguity by proposing a physically consistent model of\nthe bulk contribution which is based on a minimal set of assumptions of\nexperimental relevance. To this end, we derive an explicit integral expression\nfor the background scattering, which can be determined numerically from the\nstatic structure factors of the coexisting bulk phases as independent input.\nConcerning the interpretation of GIXRD data inferred from computer simulations,\nwe account also for the finite sizes of the bulk phases, which are unavoidable\nin simulations. The corresponding leading-order correction beyond the dominant\ncontribution to the scattered intensity is revealed by asymptotic analysis,\nwhich is characterized by the competition between the linear system size and\nthe X-ray penetration depth in the case of simulations. Specifically, we have\ncalculated the expected GIXRD intensity for scattering at the planar\nliquid--vapor interface of Lennard-Jones fluids with truncated pair\ninteractions via extensive, high-precision simulations. The reported data cover\ninterfacial and bulk properties of fluid states along the whole liquid--vapor\ncoexistence line. A sensitivity analysis demonstrates the robustness of our\nfindings concerning the detailed definition of the mean interface position. We\nconclude that previous claims of an enhanced surface tension at mesoscopic\nscales are amenable to unambiguous tests via scattering experiments.",
        "positive": "Force dipoles and stable local defects on fluid vesicles: An exact description is provided of an almost spherical fluid vesicle with a\nfixed area and a fixed enclosed volume locally deformed by external normal\nforces bringing two nearby points on the surface together symmetrically. The\nconformal invariance of the two-dimensional bending energy is used to identify\nthe distribution of energy as well as the stress established in the vesicle.\nWhile these states are local minima of the energy, this energy is degenerate;\nthere is a zero mode in the energy fluctuation spectrum, associated with area\nand volume preserving conformal transformations, which breaks the symmetry\nbetween the two points. The volume constraint fixes the distance $S$, measured\nalong the surface, between the two points; if it is relaxed, a second zero mode\nappears, reflecting the independence of the energy on $S$; in the absence of\nthis constraint a pathway opens for the membrane to slip out of the defect.\nLogarithmic curvature singularities in the surface geometry at the points of\ncontact signal the presence of external forces. The magnitude of these forces\nvaries inversely with $S$ and so diverges as the points merge; the\ncorresponding torques vanish in these defects. The geometry behaves near each\nof the singularities as a biharmonic monopole, in the region between them as a\nsurface of constant mean curvature, and in distant regions as a biharmonic\nquadrupole. Comparison of the distribution of stress with the quadratic\napproximation in the height functions points to shortcomings of the latter\nrepresentation. Radial tension is accompanied by lateral compression, both near\nthe singularities and far away, with a crossover from tension to compression\noccurring in the region between them."
    },
    {
        "anchor": "Scale Separation of Shear-induced Criticality in Glasses: In a sheared steady state, glasses reach a nonequilibrium criticality called\nyielding. In this letter, we report that the qualitative nature of this\nnonequilibrium critical phenomenon depends on the details of the system and\nthat responses and fluctuations are governed by different critical correlation\nlengths in specific situations. This scale separation of critical lengths\narises when the screening of elastic propagation of mechanical signals is not\nnegligible. We also explain that the impact of the screening effects is\ncrucially determined by the microscopic dissipation mechanism.",
        "positive": "Perspective: Geometrically-Frustrated Assemblies: This perspective will overview an emerging paradigm for self-organized soft\nmaterials, {\\it geometrically-frustrated assemblies}, where interactions\nbetween self-assembling elements (e.g. particles, macromolecules, proteins)\nfavor local packing motifs that are incompatible with uniform global order in\nthe assembly. This classification applies to a broad range of material\nassemblies including self-twisting protein filament bundles, amyloid fibers,\nchiral smectics and membranes, particle-coated droplets, curved protein shells\nand phase-separated lipid vesicles. In assemblies, geometric frustration leads\nto a host of anomalous structural and thermodynamic properties, including\nheterogeneous and internally-stressed equilibrium structures, self-limiting\nassembly and topological defects in the equilibrium assembly structures. The\npurpose of this perspective is to 1) highlight the unifying principles and\nconsequences of geometric frustration in soft matter assemblies, 2) to classify\nthe known distinct \"modes\" of frustration and review corresponding experimental\nexamples, and 3) to describe outstanding questions not yet addressed about the\nunique properties and behaviors of this broad class of systems."
    },
    {
        "anchor": "Entanglements in Quiescent and Sheared Polymer Melts: We visualize entanglements in polymer melts using molecular dynamics\nsimulation. A bead at an entanglement interacts persistently for long times\nwith the non-bonded beads (those excluding the adjacent ones in the same\nchain). The interaction energy of each bead with the non-bonded beads is\naveraged over a time interval $\\tau$ much longer than microscopic times but\nshorter than the onset time of tube constraints $\\tau_{\\rm e}$. Entanglements\ncan then be detected as hot spots consisting of several beads with relatively\nlarge values of the time-averaged interaction energy. We next apply a shear\nflow with rate much faster than the entangle motion. With increasing strain the\nchains take zigzag shapes and a half of the hot spots become bent. The chains\nare first stretched as a network but, as the bends approach the chain ends,\ndisentanglements subsequently occur, leading to stress overshoot observed\nexperimentally.",
        "positive": "Super-Arrhenius diffusion in a binary colloidal mixture at low volume\n  fraction: an effect of depletion interaction due to an asymmetric barrier: We report results from the molecular dynamics simulations of a binary\ncolloidal mixture subjected to an external potential barrier along one of the\nspatial directions at low volume fraction, {\\phi} = 0.2. The variations in the\nasymmetry of the external potential barrier do not change the dynamics of the\nsmaller particles, showing Arrhenius diffusion. However, the dynamics of the\nlarger particles shows a crossover from sub-Arrhenius to super-Arrhenius\ndiffusion with the asymmetry in the external potential at the low temperatures\nand low volume fraction. Super-Arrhenius diffusion is generally observed in the\nhigh density systems where the transient cages are present due to dense\npacking, e.g., supercooled liquids, jammed systems, diffusion through porous\nmembranes, dynamics within the cellular environment, etc. This model can be\napplied to study the molecular transport across cell membranes, nano-, and\nmicro-channels which are characterized by spatially asymmetric potentials."
    },
    {
        "anchor": "High Aspect Ratio Sub-Micrometer Channels Using Wet Etching: Application\n  to the Dynamics of Red Blood Cell Transiting through Biomimetic Splenic Slits: Nanoparticles delivering drugs, disseminating cancer cells, and red blood\ncells (RBCs) during splenic filtration must deform and pass through the\nsub-micrometer and high aspect ratio interstices between the endothelial cells\nlining blood vessels. The dynamics of passage of particles/cells through these\nslit-like interstices remain poorly understood because the in vitro\nreproduction of slits with physiological dimensions in devices compatible with\noptical microscopy observations requires expensive technologies. Here, novel\nmicrofluidic PDMS devices containing high aspect ratio slits with\nsub-micrometer width are molded on silicon masters using a simple, inexpensive,\nand highly flexible method combining standard UV lithography and anisotropic\nwet etching. These devices enabled revealing novel modes of deformations of\nhealthy and diseased RBCs squeezing through splenic-like slits (0.6--2 um 5--10\num 1.6--11 $\\mu$m3) under physiological interstitial pressures. At the slit\nexit, the cytoskeleton of spherocytic RBCs seemed to be detached from the lipid\nmembrane whereas RBCs from healthy donors and patients with sickle cell disease\nexhibited peculiar tips at their front. These tips disappeared much slower in\npatients' cells, allowing estimating a threefold increase in RBC cytoplasmic\nviscosity in sickle cell disease. Measurements of time and rate of RBC\nsequestration in the slits allowed quantifying the massive trapping of\nspherocytic RBCs.",
        "positive": "A mode-coupling theory for the glassy dynamics of a diatomic probe\n  molecule immersed in a simple liquid: Generalizing the mode-coupling theory for ideal liquid-glass transitions,\nequations of motion are derived for the correlation functions describing the\nglassy dynamics of a diatomic probe molecule immersed in a simple glass-forming\nsystem. The molecule is described in the interaction-site representation and\nthe equations are solved for a dumbbell molecule consisting of two fused hard\nspheres in a hard-sphere system. The results for the molecule's arrested\nposition in the glass state and the reorientational correlators for\nangular-momentum index $\\ell = 1$ and $\\ell = 2$ near the glass transition are\ncompared with those obtained previously within a theory based on a\ntensor-density description of the molecule in order to demonstrate that the two\napproaches yield equivalent results. For strongly hindered reorientational\nmotion, the dipole-relaxation spectra for the $\\alpha$-process can be mapped on\nthe dielectric-loss spectra of glycerol if a rescaling is performed according\nto a suggestion by Dixon et al. [Phys. Rev. Lett. {\\bf 65}, 1108 (1990)]. It is\ndemonstrated that the glassy dynamics is independent of the molecule's inertia\nparameters."
    },
    {
        "anchor": "Apparent finite-size effects in the dynamics of supercooled liquids: Molecular dynamics simulations are performed for a supercooled simple liquid\nwith changing the system size from N=108 to $10^4$ to examine possible\nfinite-size effects. Although almost no systematic deviation is detected in the\nstatic pair correlation functions, it is demonstrated that the structural\n$\\alpha$ relaxation in a small system becomes considerably slower than that in\nlarger systems for temperatures below $T_c$ at which the size of the\ncooperative particle motions becomes comparable to the unit cell length of the\nsmall system. The discrepancy increases with decreasing temperature.",
        "positive": "Semi-permeable vesicles composed of natural clay: We report a simple route to form robust, inorganic, semi-permeable\ncompartments composed of montmorillonite, a natural plate-like clay mineral\nthat occurs widely in the environment. Mechanical forces due to shear in a\nnarrow gap assemble clay nanoplates from an aqueous suspension onto air\nbubbles. Translucent vesicles suspended in a single-phase liquid are produced\nwhen the clay-covered air bubbles are exposed to a variety of water-miscible\norganic liquids. These vesicles of clay are mechanically robust and are stable\nin water and other liquids. The formation of clay vesicles can be described by\na physical mechanism that recognizes changes in the wetting characteristics of\nclay-covered air bubbles in organic liquids. The clay vesicles are covered with\nsmall pores and so intrinsically exhibit size-selective permeability, which\nallows spontaneous compartmentalization of self-assembling molecules in aqueous\nenvironments. The results we report here expand our understanding of potential\npaths to micro-compartmentalization in natural settings and are of relevance to\ntheories of colloidal aggregation, mineral cycles, and the origins of life."
    },
    {
        "anchor": "DNA self-organization controls valence in programmable colloid design: Just like atoms combine into molecules, colloids can self-organize into\npredetermined structures according to a set of design principles. Controlling\nvalence -- the number of inter-particle bonds -- is a prerequisite for the\nassembly of complex architectures. The assembly can be directed via solid\n`patchy' particles with prescribed geometries to make, for example, a colloidal\ndiamond. We demonstrate here that the nanoscale ordering of individual\nmolecular linkers can combine to program the structure of microscopic\nassemblies. Specifically, we experimentally show that covering initially\nisotropic microdroplets with $N$ mobile DNA linkers results in spontaneous and\nreversible self-organization of the DNA into $Z(N)$ binding patches, selecting\na predictable valence. We understand this valence thermodynamically, deriving a\nfree energy functional for droplet-droplet adhesion that accurately predicts\nthe equilibrium size of and molecular organization within patches, as well as\nthe observed valence transitions with $N$. Thus, microscopic self-organization\ncan be programmed by choosing the molecular properties and concentration of\nbinders. These results are widely applicable to the assembly of any particle\nwith mobile linkers, such as functionalized liposomes or protein interactions\nin cell-cell adhesion.",
        "positive": "Measurements of the Yield Stress in Frictionless Granular Systems: We perform extensive molecular dynamics simulations of 2D frictionless\ngranular materials to determine whether these systems can be characterized by a\nsingle static yield shear stress. We consider boundary-driven planar shear at\nconstant volume and either constant shear force or constant shear velocity.\nUnder steady flow conditions, these two ensembles give similar results for the\naverage shear stress versus shear velocity. However, near jamming it is\npossible that the shear stress required to initiate shear flow can differ\nsubstantially from the shear stress required to maintain flow. We perform\nseveral measurements of the shear stress near the initiation and cessation of\nflow. At fixed shear velocity, we measure the average shear stress\n$\\Sigma_{yv}$ in the limit of zero shear velocity. At fixed shear force, we\nmeasure the minimum shear stress $\\Sigma_{yf}$ required to maintain steady flow\nat long times. We find that in finite-size systems $\\Sigma_{yf} > \\Sigma_{yv}$,\nwhich implies that there is a jump discontinuity in the shear velocity from\nzero to a finite value when these systems begin flowing at constant shear\nforce. However, our simulations show that the difference $\\Sigma_{yf} -\n\\Sigma_{yv}$, and thus the discontinuity in the shear velocity, tend to zero in\nthe infinite system size limit. Thus, our results indicate that in the large\nsystem limit, frictionless granular systems are characterized by a single\nstatic yield shear stress. We also monitor the short-time response of these\nsystems to applied shear and show that the packing fraction of the system and\nshape of the velocity profile can strongly influence whether or not the shear\nstress at short times overshoots the long-time average value."
    },
    {
        "anchor": "Combined Description of Pressure-Volume-Temperature and Dielectric\n  Relaxation of Several Polymeric and Low-Molecular-Weight Organic\n  Glass-Formers using 'SL-TS2' Mean-Field Approach: We apply our recently-developed mean-field 'SL-TS2' (two-state\nSanchez-Lacombe) model to simultaneously describe dielectric alpha-relaxation\ntime and pressure-volume-temperature (PVT) data in four polymers (polystyrene,\npoly(methylmethacrylate), poly(vinyl acetate) and poly(cyclohexane methyl\nacrylate)) and four organic molecular glass formers (ortho-terphenyl, glycerol,\nPCB-62, and PDE). Previously, it has been shown that for all eight materials,\nthe Casalini-Roland thermodynamical scaling, /tau_{/alpha} =\nf(TV_{sp}^{/gamma}) (where T is temperature and V_{sp} is specific volume),\n(Casalini, R.; Roland, C. M. Phys. Rev. Lett. 2014, 113 (8), 85701), is\nsatisfied. It has also been previously shown that the same scaling emerges\nnaturally (for sufficiently low pressures) within the 'SL-TS2' framework\n(Ginzburg, V. V. Soft Matter 2021, 17, 9094). Here, we fit the ambient pressure\ncurves for the relaxation time and the specific volume as functions of\ntemperature for the eight materials and observe a good agreement between theory\nand experiment. We then use the Casalini-Roland scaling to convert those\nresults into 'master curves', thus enabling predictions of relaxation times and\nspecific volumes at elevated pressures. The proposed approach can be used to\ndescribe other glass-forming materials, both low-molecular-weight and\npolymeric.",
        "positive": "Tunable dynamic moduli of magnetic elastomers: from X-$\u03bc$CT\n  characterization to mesoscopic modeling: Ferrogels and magnetoelastomers are composite materials obtained by embedding\nmagnetic particles of mesoscopic size in a crosslinked polymeric matrix. They\ncombine the reversible elastic deformability of polymeric materials with the\nhigh responsivity of ferrofluids to external magnetic fields. These materials\nstand out, for example, for large magnetostriction as well as significant\nincrease of the elastic moduli in the presence of external magnetic fields. By\nmeans of X-ray micro-computed tomography, position and size of each magnetic\nparticle can be measured with a high degree of accuracy. We here use data\nextracted from real magnetoelastic samples as input for coarse-grained\ndipole-spring modeling and calculations to investigate magnetostriction,\nstiffening, and changes in the normal modes spectrum. More precisely, we assign\nto each particle a dipole moment proportional to its volume and set a\nrandomized network of springs between them that mimics the behavior of the\npolymeric elastic matrix. Extending our previously developed methods, we\ncompute the resulting structural changes in the systems, their overall\ndistortions, as well as the frequency-dependent elastic moduli when magnetic\ninteractions are turned on. Particularly, with increasing magnetization, we\nobserve the formation of chain-like aggregates, resulting in significant\noverall deformations. Interestingly, the static elastic moduli can first show a\nslight decrease with growing amplitude of the magnetic interactions, before a\npronounced increase appears upon the chain formation. The change of the dynamic\nmoduli with increasing magnetization depends on the frequency and can even show\nnonmonotonic behavior. Overall, we demonstrate how theory and experiments can\ncomplement each other to learn more about the dynamic behavior of this\ninteresting class of materials."
    },
    {
        "anchor": "Computing stationary distributions in equilibrium and non-equilibrium\n  systems with Forward Flux Sampling: We present a method for computing stationary distributions for activated\nprocesses in equilibrium and non-equilibrium systems using Forward Flux\nSampling (FFS). In this method, the stationary distributions are obtained\ndirectly from the rate constant calculations for the forward and backward\nreactions; there is no need to perform separate calculations for the stationary\ndistribution and the rate constant. We apply the method to the non-equilibrium\nrare event problem proposed by Maier and Stein, to nucleation in a\n2-dimensional Ising system, and to the flipping of a genetic switch.",
        "positive": "Modelling Elastically-Mediated Liquid-Liquid Phase Separation: We propose a continuum theory of the liquid-liquid phase separation in an\nelastic network where phase-separated microscopic droplets rich in one fluid\ncomponent can form as an interplay of fluids mixing, droplet nucleation,\nnetwork deformation, thermodynamic fluctuation, \\emph{etc}. We find that the\nsize of the phase separated droplets decreases with the shear modulus of the\nelastic network in the form of $\\sim[\\mathrm{modulus}]^{-1/3}$ and the number\ndensity of the droplet increases almost linearly with the shear modulus\n$\\sim[\\mathrm{modulus}]$, which are verified by the experimental observations.\nPhase diagrams in the space of (fluid constitution, mixture interaction,\nnetwork modulus) are provided, which can help to understand similar phase\nseparations in biological cells and also to guide fabrications of synthetic\ncells with desired phase properties."
    },
    {
        "anchor": "Stress-dependent normal mode frequencies from the effective mass of\n  granular matter: A zero-temperature critical point has been invoked to control the anomalous\nbehavior of granular matter as it approaches jamming or mechanical arrest.\nCriticality manifests itself in an anomalous spectrum of low-frequency normal\nmodes and scaling behavior near the jamming transition. The critical point may\nexplain the peculiar mechanical properties of dissimilar systems such as\nglasses and granular materials. Here, we study the critical scenario via an\nexperimental measurement of the normal modes frequencies of granular matter\nunder stress from a pole decomposition analysis of the effective mass. We\nextract a complex-valued characteristic frequency which displays scaling\n$|\\omega^*(\\sigma)|\\sim\\sigma^{\\Omega'}$ with vanishing stress $\\sigma$ for a\nvariety of granular systems. The critical exponent is smaller than that\npredicted by mean-field theory opening new challenges to explain the exponent\nfor frictional and dissipative granular matter. Our results shed light on the\nanomalous behavior of stress-dependent acoustics and attenuation in granular\nmaterials near the jamming transition.",
        "positive": "Amplification of light and atoms in a Bose--Einstein condensate: A Bose-Einstein condensate illuminated by a single off-resonant laser beam\n(``dressed condensate'') shows a high gain for matter waves and light. We have\ncharacterized the optical and atom-optical properties of the dressed condensate\nby injecting light or atoms, illuminating the key role of long-lived matter\nwave gratings produced by the condensate at rest and recoiling atoms. The\nnarrow bandwidth for optical gain gave rise to an extremely slow group velocity\nof an amplified light pulse (1 m/s)."
    },
    {
        "anchor": "Lifetime of dynamical heterogeneity in a highly supercooled liquid: We numerically examine dynamical heterogeneity in a highly supercooled\nthree-dimensional liquid via molecular-dynamics simulations. To define the\nlocal dynamics, we consider two time intervals, $\\tau_\\alpha$ and\n$\\tau_{\\text{ngp}}$. $\\tau_\\alpha$ is the $\\alpha$ relaxation time, and\n$\\tau_{\\text{ngp}}$ is the time at which non-Gaussian parameter of the van Hove\nself-correlation function is maximized. We determine the lifetimes of the\nheterogeneous dynamics in these two different time intervals,\n$\\tau_{\\text{hetero}}(\\tau_\\alpha)$ and\n$\\tau_{\\text{hetero}}(\\tau_{\\text{ngp}})$, by calculating the time correlation\nfunction of the particle dynamics, i.e., the four-point correlation function.\nWe find that the difference between $\\tau_{\\text{hetero}}(\\tau_\\alpha)$ and\n$\\tau_{\\text{hetero}}(\\tau_{\\text{ngp}})$ increases with decreasing\ntemperature. At low temperatures, $\\tau_{\\text{hetero}}(\\tau_\\alpha)$ is\nconsiderably larger than $\\tau_{\\alpha}$, while\n$\\tau_{\\text{hetero}}(\\tau_{\\text{ngp}})$ remains comparable to\n$\\tau_{\\alpha}$. Thus, the lifetime of the heterogeneous dynamics depends\nstrongly on the time interval.",
        "positive": "Recoil experiments determine the eigenmodes of viscoelastic fluids: We experimentally investigate the recoil dynamics of a colloidal probe\nparticle after shearing it with constant velocity through a viscoelastic fluid.\nThe recoil displays two distinct timescales which are in excellent agreement\nwith a microscopic model built on a particle being linked to two bath particles\nby harmonic springs. This model yields analytical expressions which reproduce\nall experimental protocols, including additional waiting periods before\nparticle release. Notably, two sets of timescales appear, corresponding to\nreciprocal and nonreciprocal eigenmodes of the model."
    },
    {
        "anchor": "Limiting Spurious Flow in Simulations of Electrokinetic Phenomena: Electrokinetic transport phenomena can strongly influence the behaviour of\nmacromolecules and colloidal particles in solution, with applications in, e.g.,\nDNA translocation through nanopores, electro-osmotic flow in nanocapillaries,\nand electrophoresis of charged macromolecules. Numerical simulations are an\nimportant tool to investigate these electrokinetic phenomena, but are often\nplagued by spurious fluxes and spurious flows that can easily exceed physical\nfluxes and flows. Here, we present a method that reduces one of these spurious\ncurrents, spurious flow, by several orders of magnitude. We demonstrate the\neffectiveness and generality of our method for both electrokinetic\nlattice-Boltzmann and finite-element-method based algorithms by simulating a\ncharged sphere in an electrolyte solution, and flow through a nanopore. We also\nshow that previous attempts to suppress these spurious currents introduce other\nsources of error.",
        "positive": "Correlation-induced viscous dissipation in concentrated electrolytes: Electrostatic correlations between ions dissolved in water are known to\nimpact their transport properties in numerous ways, from conductivity to ion\nselectivity. The effects of these correlations on the solvent itself remain,\nhowever, much less clear. In particular, the addition of salt has been\nconsistently reported to affect the solution's viscosity -- but most modelling\nattempts fail to reproduce experimental data even at moderate salt\nconcentration. Here, we use an approach based on stochastic density functional\ntheory, which accurately captures charge fluctuations and correlations. We\nderive a simple analytical expression for the viscosity correction in\nconcentrated electrolytes, by directly linking it to the liquid's structure\nfactor. Our prediction compares quantitatively to experimental data at all\ntemperatures and all salt concentrations up to the saturation limit. This\nuniversal link between microscopic structure and viscosity allows to shed light\non the nanoscale dynamics of water and ions in highly concentrated and\ncorrelated conditions."
    },
    {
        "anchor": "Low Stress Ion Conductance Microscopy of Sub-Cellular Stiffness: Directly examining subcellular mechanics whilst avoiding excessive strain of\na live cell requires the precise control of light stress on very small areas,\nwhich is fundamentally difficult. Here we use a glass nanopipet out of contact\nwith the plasma membrane to both exert the stress on the cell and also\naccurately monitor cellular compression. This allows the mapping of cell\nstiffness at a lateral resolution finer than 100 nm. We calculate the stress a\nnanopipet exerts on a cell as the sum of the intrinsic pressure between the tip\nface and the plasma membrane plus its direct pressure on any glycocalyx, both\nevaluated from the gap size in terms of the ion current decrease. A survey of\ncell types confirms that an intracellular pressure of approximately 120 Pa\nbegins to detach the plasma membrane from the cytoskeleton and reveals that the\nfirst 660 +/- 90 nm of compression of a neuron cell body is much softer than\nprevious methods have been able to detect.",
        "positive": "A van der Waals density functional mapping of attraction in DNA dimers: The dispersion interaction between a pair of parallel DNA double-helix\nstructures is investigated by means of the van der Waals density functional\n(vdW-DF) method. Each double-helix structure consists of an infinite repetition\nof one B-DNA coil with 10 base pairs. This parameter-free density functional\ntheory (DFT) study illustrates the initial step in a proposed vdW-DF\ncomputational strategy for large biomolecular problems. The strategy is to\nfirst perform a survey of interaction geometries, based on the evaluation of\nthe van der Waals (vdW) attraction, and then limit the evaluation of the\nremaining DFT parts (specifically the expensive study of the kinetic-energy\nrepulsion) to the thus identified interesting geometries. Possibilities for\naccelerating this second step is detailed in a separate study. For the B-DNA\ndimer, the variation in van der Waals attraction is explored at relatively\nshort distances (although beyond the region of density overlap) for a 360\ndegrees rotation. This study highlights the role of the structural motifs, like\nthe grooves, in enhancing or reducing the vdW interaction strength. We find\nthat to a first approximation, it is possible to compare the DNA double strand\nat large wall-to-wall separations to the cylindrical shape of a carbon nanotube\n(which is almost isotropic under rotation). We compare our first-principles\nresults with the atom-based dispersive interaction predicted by DFT-D2 [J.\nComp. Chem. 27, 1787 (2006)] and find agreement in the asymptotic region.\nHowever, we also find that the differences in the enhancement that occur at\nshorter distances reveal characteristic features that result from the fact that\nthe vdW-DF method is an electron-based (as opposed to atom-based) description."
    },
    {
        "anchor": "Rheology of granular particles immersed in a molecular gas under uniform\n  shear flow: Non-Newtonian transport properties of a dilute gas of inelastic hard spheres\nimmersed in a molecular gas are determined. We assume that the granular gas is\nsufficiently rarefied and hence, the state of the molecular gas is not\ndisturbed by the presence of the solid particles. In this situation, one can\ntreat the molecular gas as a bath (or thermostat) of elastic hard spheres at a\ngiven temperature. Moreover, in spite of the fact that the number density of\ngrains is quite small, we take into account their inelastic collisions among\nthemselves in its kinetic equation. The system (granular gas plus a bath of\nelastic hard spheres) is subjected to a simple (or uniform) shear flow (USF).\nIn the low-density regime, the rheological properties of the granular gas are\ndetermined by solving the Boltzmann kinetic equation by means of Grad's moment\nmethod. These properties turn out to be highly nonlinear functions of the shear\nrate and the remaining parameters of the system. Our results show that the\nkinetic granular temperature and the non-Newtonian viscosity present a\ndiscontinuous shear thickening (DST) effect for sufficiently high values of the\nmass ratio $m/m_g$ ($m$ and $m_g$ being the mass of grains and gas particles,\nrespectively). This effect becomes more pronounced as the mass ratio $m/m_g$\nincreases. In particular, in the Brownian limit ($m_g/m\\to 0$) the expressions\nof the non-Newtonian transport properties derived here are consistent with\nthose previously obtained by considering a coarse-grained approach where the\neffect of gas phase on grains is through an effective force. Theoretical\nresults are compared against computer simulations in the Brownian limit showing\nan excellent agreement.",
        "positive": "Inherent variability in the kinetics of autocatalytic protein\n  self-assembly: In small volumes, the kinetics of filamentous protein self-assembly is\nexpected to show significant variability, arising from intrinsic molecular\nnoise. This is not accounted for in existing deterministic models. We introduce\na simple stochastic model including nucleation and autocatalytic growth via\nelongation and fragmentation, which allows us to predict the effects of\nmolecular noise on the kinetics of autocatalytic self-assembly. We derive an\nanalytic expression for the lag-time distribution, which agrees well with\nexperimental results for the fibrillation of bovine insulin. Our expression\ndecomposes the lag time variability into contributions from primary nucleation\nand autocatalytic growth and reveals how each of these scales with the key\nkinetic parameters. Our analysis shows that significant lag-time variability\ncan arise from both primary nucleation and from autocatalytic growth, and\nshould provide a way to extract mechanistic information on early-stage\naggregation from small-volume experiments."
    },
    {
        "anchor": "Simulation of Dislocation in Cosserat Elastic Plates: In this article we present the numerical simulation of a dislocation\nincorporated into a Cosserat plate. The simulation is based on the mathematical\nmodel for bending of Cosserat elastic plates recently developed by the authors.\nThe dislocation is modeled by a sequence of domains that converge to the point\nof the dislocation and by a residual force distributed around that point. The\nresulted plate deformation is calculated using the Finite Element method. We\nalso discuss a possible effect of the dislocation on a hole incorporated into\nthe plate.",
        "positive": "A novel particle tracking method with individual particle size\n  measurement and its application to ordering in glassy hard sphere colloids: Particle tracking is a key to single-particle-level confocal microscopy\nobservation of colloidal suspensions, emulsions, and granular matter. The\nconventional tracking method has not been able to provide accurate information\non the size of individual particle. Here we propose a novel method to localise\nspherical particles of arbitrary relative sizes from either 2D or 3D (confocal)\nimages either in dilute or crowded environment. Moreover this method allows us\nto estimate the size of each particle reliably. We use this method to analyse\nlocal bond orientational ordering in a supercooled polydisperse colloidal\nsuspension as well as the heterogeneous crystallisation induced by a substrate.\nFor the former, we reveal non-trivial couplings of crystal-like bond\norientational order and local icosahedral order with the spatial distribution\nof particle sizes: Crystal-like order tends to form in regions where very small\nparticles are depleted and the slightly smaller size of the central particle\nstabilizes icosahedral order. For the latter, on the other hand, we found that\nvery small particles are expelled from crystals and accumulated on the growth\nfront of crystals. We emphasize that such information has not been accessible\nby conventional tracking methods."
    },
    {
        "anchor": "Stress Fluctuations in Transient Active Networks: Inspired by experiments on dynamic extensile gels of biofilaments and motors,\nwe propose a model of a network of linear springs with a kinetics consisting of\ngrowth at a prescribed rate, death after a lifetime drawn from a distribution,\nand birth at a randomly chosen node. The model captures features such as the\nbuild-up of self-stress, that are not easily incorporated into hydrodynamic\ntheories. We study the model numerically and show that our observations can\nlargely be understood through a stochastic effective-medium model. The\nresulting dynamically extending force-dipole network displays many features of\nyielded plastic solids, and offers a way to incorporate strongly non-affine\neffects into theories of active solids. A rather distinctive form for the\nstress distribution, and a Herschel-Bulkley dependence of stress on activity,\nare our major predictions.",
        "positive": "Thermal versus entropic Mpemba effect in molecular gases with nonlinear\n  drag: Loosely speaking, the Mpemba effect appears when hotter systems cool sooner\nor, in a more abstract way, when systems further from equilibrium relax faster.\nIn this paper, we investigate the Mpemba effect in a molecular gas with\nnonlinear drag, both analytically (by employing the tools of kinetic theory)\nand numerically (direct simulation Monte Carlo of the kinetic equation and\nevent-driven molecular dynamics). The analysis is carried out via two\nalternative routes, recently considered in the literature: first, the kinetic\nor thermal route, in which the Mpemba effect is characterized by the crossing\nof the evolution curves of the kinetic temperature (average kinetic energy),\nand, second, the stochastic thermodynamics or entropic route, in which the\nMpemba effect is characterized by the crossing of the distance to equilibrium\nin probability space. In general, a nonmutual correspondence between the\nthermal and entropic Mpemba effects is found, i.e., there may appear the\nthermal effect without its entropic counterpart or vice versa. Furthermore, a\nnontrivial overshoot with respect to equilibrium of the thermal relaxation\nmakes it necessary to revise the usual definition of the thermal Mpemba effect,\nwhich is shown to be better described in terms of the relaxation of the local\nequilibrium distribution. Our theoretical framework, which involves an extended\nSonine approximation in which not only the excess kurtosis but also the sixth\ncumulant is retained, gives an excellent account of the behavior observed in\nsimulations."
    },
    {
        "anchor": "Dense pedestrian crowds versus granular packings: An analogy of sorts: Analogies between the dynamics of pedestrian crowds and granular media have\nlong been hinted at.They seem all the more promising as the crowd is (very)\ndense, in which case the mechanical constraints prohibiting overlapsmight\nprevail over the decisional component of pedestrian dynamics. These analogies\nand their origins are probed in two distinct settings, (i) a flow through a\nnarrow bottleneck and (ii) crossing of a static assembly by an intruder.\nSeveral quantitative similarities have been reported for the former setting and\nare discussed here, while setting (ii) reveals discrepancies in the response\npattern, which areascribed to the pedestrians' ability to perceive, anticipate\nand self-propel.",
        "positive": "Active phase separation by turning toward regions of higher density: Studies of active matter, from molecular assemblies to animal groups, have\nrevealed two broad classes of behavior: a tendency to align yields\norientational order and collective motion, whereas particle repulsion leads to\nself-trapping and motility-induced phase separation. Here, we report a third\nclass of behavior: orientational interactions that produce active phase\nseparation. Combining theory and experiments on self-propelled Janus colloids,\nwe show that stronger repulsion on the rear than on the front of these\nparticles produces non-reciprocal torques that reorient particle motion toward\nhigh-density regions. Particles thus self-propel toward crowded areas, which\nleads to phase separation. Clusters remain fluid and exhibit fast particle\nturnover, in contrast to the jammed clusters that typically arise from\nself-trapping, and interfaces are sufficiently wide that they span entire\nclusters. Overall, our work identifies a torque-based mechanism for phase\nseparation in active fluids, and our theory predicts that these orientational\ninteractions yield coexisting phases that lack internal orientational order."
    },
    {
        "anchor": "Marginal Stability Enables Memory Training in Jammed Solids: Memory encoding by cyclic shear is a reliable process to store information in\njammed solids, yet its underlying mechanism and its connection to the amorphous\nstructure are not fully understood. When a jammed sphere packing is repeatedly\nsheared with cycles of the same strain amplitude, it optimizes its mechanical\nresponse to the cyclic driving and stores a memory of it. We study memory by\ncyclic shear training as a function of the underlying stability of the\namorphous structure in marginally stable and highly stable packings, the latter\nproduced by minimizing the potential energy using both positional and radial\ndegrees of freedom. We find that jammed solids need to be marginally stable in\norder to store a memory by cyclic shear. In particular, highly stable packings\nstore memories only after overcoming brittle yielding and the cyclic shear\ntraining takes place in the shear band, a region which we show to be marginally\nstable.",
        "positive": "Energy decay in three-dimensional freely cooling granular gas: The kinetic energy of a freely cooling granular gas decreases as a power law\n$t^{-\\theta}$ at large times $t$. Two theoretical conjectures exist for the\nexponent $\\theta$. One based on ballistic aggregation of compact spherical\naggregates predicts $\\theta= 2d/(d+2)$ in $d$ dimensions. The other based on\nBurgers equation describing anisotropic, extended clusters predicts\n$\\theta=d/2$ when $2\\le d \\le 4$. We do extensive simulations in three\ndimensions to find that while $\\theta$ is as predicted by ballistic\naggregation, the cluster statistics and velocity distribution differ from it.\nThus, the freely cooling granular gas fits to neither the ballistic aggregation\nor a Burgers equation description."
    },
    {
        "anchor": "Nonlocal tensor order parameter of the deformed state of liquid crystals: A generalized notion of a nonlocal tensor order parameter is introduced\nwithin the framework of the phenomenological approach. This parameter has the\nform of a traceless tensor correlation function or a tensor integral operator.\nBased on this form, the governing relations are written, which determine the\nsteady states and phase transitions of the deformed liquid crystal. Linear\nrelations for eigenfunctions of the introduced operator are derived. A\nprincipal drawback of currently available models of liquid crystals based on\nthe local presentation of the tensor order parameter (equality of two Frank\nconstants in the case of a quadratic form of the strain part of the free\nenergy) is eliminated. Particular examples are considered, which demonstrate\nthe model workability and the absence of contradictions in the model as well as\nits adequacy when describing small-scale structures.",
        "positive": "Smectic phases in ionic liquid crystals: Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which carry\ncharges and therefore combine properties of liquid crystals, e.g., the\nformation of mesophases, and of ionic liquids, such as low melting temperatures\nand tiny triple-point pressures. Previous density functional calculations have\nrevealed that the phase behavior of ILCs is strongly affected by their\nmolecular properties, i.e., their aspect ratio, the loci of the charges, and\ntheir interaction strengths. Here, we report new findings concerning the phase\nbehavior of ILCs as obtained by density functional theory and Monte Carlo\nsimulations. The most important result is the occurrence of a novel, wide\nsmectic-A phase $S_{AW}$, at low temperature, the layer spacing of which is\nlarger than that of the ordinary high-temperature smectic-A phase $S_{A}$.\nUnlike the ordinary smectic $S_A$ phase, the structure of the $S_{AW}$ phase\nconsists of alternating layers of particles oriented parallel to the layer\nnormal and oriented perpendicular to it."
    },
    {
        "anchor": "Physics of base-pairing dynamics in DNA: As a key molecule of Life, Deoxyribonucleic acid (DNA) is the focus of\nnumbers of investigations with the help of biological, chemical and physical\ntechniques. From a physical point of view, both experimental and theoretical\nworks have brought quantitative insights into DNA base-pairing dynamics that we\nreview in this Report, putting emphasis on theoretical developments. We discuss\nthe dynamics at the base-pair scale and its pivotal coupling with the polymer\none, with a polymerization index running from a few nucleotides to tens of\nkilo-bases. This includes opening and closure of short hairpins and oligomers\nas well as zipping and unwinding of long macromolecules. We review how\ndifferent physical mechanisms are either used by Nature or utilized in\nbiotechnological processes to separate the two intertwined DNA strands, by\ninsisting on quantitative results. They go from thermally-assisted denaturation\nbubble nucleation to force- or torque- driven mechanisms. We show that the\nhelical character of the molecule, possibly supercoiled, can play a key role in\nmany denaturation and renaturation processes. We categorize the mechanisms\naccording to the relative timescales associated with base-pairing and chain\ndegrees of freedom such as bending and torsional elastic ones. In some specific\nsituations, these chain degrees of freedom can be integrated out, and the\nquasi- static approximation is valid. The complex dynamics then reduces to the\ndiffusion in a low-dimensional free-energy landscape. In contrast, some\nimportant cases of experimental interest necessarily appeal to\nfar-from-equilibrium statistical mechanics and hydrodynamics.",
        "positive": "Memory induced Magnus effect: Spinning objects which move through air or liquids experience a Magnus force.\nThis effect is commonly exploited in ball sports but also of considerable\nimportance for applications and fundamental science. Opposed to large objects\nwhere Magnus forces are strong, they are only weak at small scales and\neventually vanish for overdamped micron-sized particles in simple liquids. Here\nwe demonstrate an about one-million-fold enhanced Magnus force of spinning\ncolloids in viscoelastic fluids. Such fluids are characterized by a\ntime-delayed response to external perturbations which causes a deformation of\nthe fluidic network around the moving particle. When the particle additionally\nspins, the deformation field becomes misaligned relative to the particle's\nmoving direction, leading to a force perpendicular to the direction of travel\nand the spinning axis. The presence of strongly enhanced memory-induced Magnus\nforces at microscales opens novel applications for particle sorting and\nsteering, the creation and visualization of anomalous flows and more."
    },
    {
        "anchor": "Shear-wave manipulation by embedded soft devices: Hyperelastic transformation theory has proven shear-wave manipulation devices\nwith various functions can be designed by utilizing neo-Hookean material with\nappropriate pre-deformation. However, it is still elusive that how can such\ndevices match with the background medium in which they embedded. In this work,\nwe present a systematic formulation of the transmission and reflection of\nelastic waves at the interface between un-deformed and pre-deformed\nhyperelastic materials. With the combination of theoretical analyses and\nnumerical simulations, we specifically investigate the shear-wave propagation\nfrom an un-deformed neo-Hookean material to the one subject to different\nhomogeneous deformations. Among three typical deformation modes, we found\n\"constrained\" uniaxial tension and simple shear guarantee total transmission,\nwhereas \"ordinary\" uniaxial tension and hydrostatic compression cause wave\nreflection. On this basis, three embedded shear-wave manipulation devices,\nincluding a unidirectional cloak, a splicable beam bend, and a concave lens,\nare proposed and verified through numerical simulations. This work may pave the\nway for the design and realization of soft-matter-based wave control devices.\nPotential applications can be anticipated in nondestructive testing, structure\nimpact protection, biomedical imaging, and soft robotics.",
        "positive": "A mathematical and experimental study on iron rings formation in porous\n  stones: In this interdisciplinary paper, we study the formation of iron precipitates\n- the so-called Liesegang rings - in Lecce stones in contact with iron source.\nThese phenomena are responsible of exterior damages of lapideous artifacts, but\nalso in the weakening of their structure. They originate in presence of water,\ndetermining the flow of carbonate compunds mixing with the iron ions and then,\nafter a sequence of reactions and precipitation, leading to the formation of\nLiesegang rings. In order to model these phenomena observed in situ and in\nlaboratory experiments, we propose a modification of the classical\nKeller-Rubinow model and show the results obtained with some numerical\nsimulations, in comparison with the experimental tests. Our model is of\ninterest for a better understanding of damage processes in monumental stones."
    },
    {
        "anchor": "Numerical evidence for nucleated self-assembly of DNA brick structures: The observation by Ke et al. [Science 338, 1177 (2012)] that large numbers of\nshort, pre-designed DNA strands can assemble into three-dimensional target\nstructures came as a great surprise, as no colloidal self-assembling system has\never achieved the same degree of complexity. That failure seemed easy to\nrationalise: the larger the number of distinct building blocks, the higher the\nexpected error rate for self-assembly. The experiments of Ke et al. have\ndisproved this argument. Here, we report Monte Carlo simulations of the\nself-assembly of a DNA brick cube, comprising approximately 1000 types of DNA\nstrand, using a simple model. We model the DNA strands as lattice tetrahedra\nwith attractive patches, the interaction strengths of which are computed using\na standard thermodynamic model. We find that, within a narrow temperature\nwindow, the target structure assembles with high probability. Our simulations\nsuggest that mis-assembly is disfavoured because of a slow nucleation step. As\nour model incorporates no aspect of DNA other than its binding properties,\nthese simulations suggest that, with proper design of the building blocks,\nother systems, such as colloids, may also assemble into truly complex\nstructures.",
        "positive": "Hyperelastic swelling of tough hydrogels: Hydrogels are biphasic, swollen polymer networks where elastic deformation is\ncoupled to nanoscale fluid flow. As a consequence, hydrogels can withstand\nlarge strains and exhibit nonlinear, hyperelastic properties. For low-modulus\nhydrogel and semiflexible biopolymer networks, previous studies have shown that\nthese materials universally contract when sheared on timescales much longer\nthan the poroelastic relaxation timescale. Using rheological and tribological\nmeasurements, we find that tough polyacrylamide and polyacrylic acid hydrogels,\nwith moduli of order ~10-100 kPa, exclusively exhibit dilatancy when sheared.\nThe poroelastic relaxation process was examined using strain-controlled\ncompression, indicating a diffusion constant of order 10^-9 m^2/s. On short\ntimescales (minutes), an applied shear stress induced an increase in normal\nstress that varied quadratically with shear strain. At long timescales (hours),\ncreep experiments revealed that tough hydrogels can ``remember'' the initial\ndirection of applied shear, suggesting an evolution of the polymer network.\nMoreover, we show that this dilatant behavior manifests as swelling during\ntribological sliding, imbibing the hydrogel with fluid. We suggest that this\ninherent, hyperelastic dilatancy is an important feature in all tough\nhydrogels, and may explain rehydration and mechanical rejuvenation in\nbiological tissues such as cartilage."
    },
    {
        "anchor": "Entanglement on nucleation barrier of polymer crystal: We propose a theoretical approach to quantitatively account for the role of\nentanglement in the nucleation of polymer melts, which is the unique feature of\npolymer differentiated from small molecules. By performing molecular dynamics\nsimulations, we obtain the nucleation barriers of polymer systems with\ndifferent entanglement densities, which exhibits an opposite trend compared to\nthe prediction of the classic nucleation theory (CNT). To amend the deficiency\nof the CNT in polymer crystallization, we introduce the entanglement free\nenergy to reflect the role of entanglement in polymer nucleation. Specifically,\nthe polymer nucleation not only involves free energies of monomers inside and\non the surface of a nucleus as considered in the CNT, but also affects the\nentanglement network around the nucleus. Our theoretical approach provides a\nreasonable interpretation for the unsolved nucleation phenomena of polymers in\nsimulations and experiments.",
        "positive": "Untwisting of a cholesteric elastomer by a mechanical field: A mechanical strain field applied to a monodomain cholesteric elastomer will\nunwind the helical director distribution. There is an analogy with the\nclassical problem of an electric field applied to a cholesteric liquid crystal,\nbut with important differences. Frank elasticity is of minor importance unless\nthe gel is very weak. The interplay is between director anchoring to the rubber\nelastic matrix and the external mechanical field. Stretching perpendicular to\nthe helix axis induces the uniform unwound state via the elimination of sharp,\npinned twist walls above a critical strain. Unwinding through conical director\nstates occurs when the elastomer is stretched along the helical axis."
    },
    {
        "anchor": "How hydrophobic drying forces impact the kinetics of molecular\n  recognition: A model of protein-ligand binding kinetics in which slow solvent dynamics\nresults from hydrophobic drying transitions is investigated. Molecular dynamics\nsimulations show that solvent in the receptor pocket can fluctuate between wet\nand dry states with lifetimes in each state that are long enough for the\nextraction of a separable potential of mean force and wet-to-dry transitions.\nWe introduce a Diffusive Surface Hopping Model that is represented by a\ntwo-dimensional Markovian master equation. One dimension is the standard\nreaction coordinate, the ligand-pocket separation, and the other is the solvent\nstate in the region between ligand and binding pocket which specifies whether\nit is wet or dry. In our model, the ligand diffuses on a dynamic free energy\nsurface which undergoes kinetic transitions between the wet and dry states. The\nmodel yields good agreement with results from explicit solvent molecular\ndynamics simulation and an improved description of the kinetics of hydrophobic\nassembly. Furthermore, it is consistent with a \"non-Markovian Brownian theory\"\nfor the ligand-pocket separation coordinate alone.",
        "positive": "Confined Brownian ratchets: We analyze the dynamics of Brownian ratchets in a confined environment. The\nmotion of the particles is described by a Fick-Jakobs kinetic equation in which\nthe presence of boundaries is modeled by means of an entropic potential. The\ncases of a flashing ratchet, a two-state model and a ratchet under the\ninfluence of a temperature gradient are analyzed in detail. We show the\nemergence of a strong cooperativity between the inherent rectification of the\nratchet mechanism and the entropic bias of the fluctuations caused by spatial\nconfinement. Net particle transport may take place in situations where none of\nthose mechanisms leads to rectification when acting individually. The combined\nrectification mechanisms may lead to bidirectional transport and to new routes\nto segregation phenomena. Confined Brownian ratchets (CBR) could be used to\ncontrol transport in mesostructures and to engineer new and more efficient\ndevices for transport at the nanoscale."
    },
    {
        "anchor": "Athermal jamming of soft frictionless Platonic solids: A mechanically-based structural optimization method is utilized to explore\nthe phenomena of jamming for assemblies of frictionless Platonic solids.\nSystems of these regular convex polyhedra exhibit mechanically stable phases\nwith density substantially less than optimal for a given shape, revealing that\nthermal motion is necessary to access high density phases. We confirm that the\nlarge system jamming threshold of $0.623 \\pm 0.003$ for tetrahedra is\nconsistent with experiments on tetrahedral dice. Also, the extremely\nshort-ranged translational correlations of packed tetrahedra observed in\nexperiments are confirmed here, in contrast with those of thermally simulated\nglasses. Though highly ordered phases are observed to form for small numbers of\ncubes and dodecahedra, the short correlation length scale suppresses ordering\nin large systems, resulting in packings that are mechanically consistent with\n`orientationally disordered' contacts (point-face and edge-edge contacts). Mild\nnematic ordering is observed for large systems of cubes, whereas angular\ncorrelations for the remaining shapes are ultra short-ranged. Power-law scaling\nexponents for energy with respect to distance from the jamming threshold\nexhibit a clear dependence on the `highest order' percolating contact topology.\nThese nominal exponents are 6, 4, and 2 for configurations having percolating\npoint-face (or edge-edge), edge-face, and face-face contacts, respectively.\nThese Platonic solids exhibit hypostatic behavior, with average jamming contact\nnumber between the isostatic value for spheres and that of asymmetric\nparticles. These shapes violate the isostatic conjecture, displaying contact\nnumber that decreases monotonically with sphericity. The common symmetry of\ndual polyhedra results in local translational structural similarity. (Note\nabstract abridged due to length constraint)",
        "positive": "Fluid contact angle on solid surfaces: role of multiscale surface\n  roughness: We present a simple analytical model and an exact numerical study which\nexplain the role of roughness on different length scales for the fluid contact\nangle on rough solid surfaces. We show that there is no simple relation between\nthe distribution of surface slopes and the fluid contact angle. In particular,\nsurfaces with the same distribution of slopes may exhibit very different\ncontact angles depending on the range of length-scales over which the surfaces\nhave roughness."
    },
    {
        "anchor": "Universal Negative Poisson Ratio of Self Avoiding Fixed Connectivity\n  Membranes: We determine the Poisson ratio of self-avoiding fixed-connectivity membranes,\nmodeled as impenetrable plaquettes, to be sigma=-0.37(6), in statistical\nagreement with the Poisson ratio of phantom fixed-connectivity membranes\nsigma=-0.32(4). Together with the equality of critical exponents, this result\nimplies a unique universality class for fixed-connectivity membranes. Our\nfindings thus establish that physical fixed-connectivity membranes provide a\nwide class of auxetic (negative Poisson ratio) materials with significant\npotential applications in materials science.",
        "positive": "Active polymer rings: activity-induced collapse and dynamical arrest: We investigate, using numerical simulations, the conformations of isolated\nactive ring polymers. We find that the their behaviour depends crucially on\ntheir size: short rings ($N \\lesssim$ 100) are swelled whereas longer rings ($N\n\\gtrsim$ 200) collapse, at sufficiently high activity. By investigating the\nnon-equilibrium process leading to the steady state, we find a universal route\ndriving both outcomes; we highlight the central role of steric interactions, at\nvariance with linear chains, and of topology conservation. We further show that\nthe collapsed rings are arrested by looking at different observables, all\nunderlining the presence of an extremely long time scales at the steady state,\nassociated with the internal dynamics of the collapsed section. Finally, we\nfound that is some circumstances the collapsed state spins about its axis."
    },
    {
        "anchor": "Stick-slip instability for viscous fingering in a gel: The growth dynamics of an air finger injected in a visco-elastic gel (a\nPVA/borax aqueous solution) is studied in a linear Hele-Shaw cell. Besides the\nstandard Saffmann-Taylor instability, we observe - with increasing finger\nvelocities - the existence of two new regimes: (a) a stick-slip regime for\nwhich the finger tip velocity oscillates between 2 different values, producing\nlocal pinching of the finger at regular intervals, (b) a ``tadpole'' regime\nwhere a fracture-type propagation is observed. A scaling argument is proposed\nto interpret the dependence of the stick-slip frequency with the measured\nrheological properties of the gel.",
        "positive": "A holed membrane at finite equibiaxial stretch: The deformation and stress distribution in a stretched thin neo-Hookean\ncircular membrane with a hole at its center are analyzed within the framework\nof finite deformation elasticity. Initially, we derive a simple form for the\ndifferential governing equation to the problem. This enables us to introduce a\nclosed-form solution in the limit of infinite stretch. Subsequently, we propose\napproximate solutions for intermediate and large deformations. These\napproximations approach the exact solutions in the limits of small and infinite\nstretches. The transition stretch at which the membrane behavior switches from\nthe intermediate to the large deformation approximation is determined too.\nComparison of our solution and approximations to corresponding numerical\nresults reveal a neat agreement for any stretch and ratio between the hole to\nthe membrane radii. In the limit of large stretches and a small hole, the ratio\nof the hoop stress at the hole boundary to the nominal stress is 4, which is\ntwice the corresponding ratio in the small deformation limit. Comparison of the\nstrain energy stored in the membrane to the one in a membrane without a hole\nreveals that only at finite stretches the difference between these energies\nbecomes meaningful. This implies that it is likely that a flaw in a membrane\nwill tear out only at a finite level of stretches."
    },
    {
        "anchor": "Characterization of Void Space, Large-Scale Structure, and Transport\n  Properties of Maximally Random Jammed Packings of Superballs: Dense, disordered packings of particles are useful models of low-temperature\namorphous phases of matter, biological systems, granular media, and colloidal\nsystems. The study of dense packings of nonspherical particles enables one to\nascertain how rotational degrees of freedom affect packing behavior. Here, we\nstudy superballs, a large family of deformations of the sphere, defined in\nthree dimensions by $|x_1|^{2p}+|x_2|^{2p}+|x_3|^{2p}\\leq1$, where $p>0$ is a\ndeformation parameter indicating to what extent the shape deviates from a\nsphere. As $p$ increases from the sphere point ($p=1$), the superball attains\ncubic symmetry, and attains octahedral symmetry when $p<1$. Previous\ncharacterization of superball packings has shown that they have a maximally\nrandom jammed (MRJ) state, whose properties (e.g., packing fraction $\\phi$)\nvary nonanalytically as $p$ diverges from unity. Here, we use an event-driven\nmolecular dynamics algorithm to produce MRJ superball packings. We characterize\ntheir large-scale structure by examining the small-$Q$ behavior of their\nstructure factors and spectral densities, which indicate these packings are\neffectively hyperuniform. We show that the mean width $\\bar{w}$ is a useful\nlength scale to make distances dimensionless in order to compare systematically\nsuperballs of different shape. We also compute the complementary cumulative\npore-size distribution $F(\\delta)$ and find the pore sizes tend to decrease as\n$|1-p|$ increases. From $F(\\delta)$, we estimate the fluid permeability, mean\nsurvival time, and principal diffusion relaxation time of the packings.\nAdditionally, we compute the diffusion spreadability and find the long-time\npower-law scaling indicates these packings are hyperuniform. Our results can be\nused to help inform the design of granular materials with targeted densities\nand transport properties.",
        "positive": "Stochastic Hydrodynamic Synchronization in Rotating Energy Landscapes: Hydrodynamic synchronization provides a general mechanism for the spontaneous\nemergence of coherent beating states in independently driven mesoscopic\noscillators. A complete physical picture of those phenomena is of definite\nimportance to the understanding of biological cooperative motions of cilia and\nflagella. Moreover, it can potentially suggest novel routes to exploit\nsynchronization in technological applications of soft matter. We demonstrate\nthat driving colloidal particles in rotating energy landscapes results in a\nstrong tendency towards synchronization, favouring states where all beads\nrotate in phase. The resulting dynamics can be described in terms of activated\njumps with transition rates that are strongly affected by hydrodynamics leading\nto an increased probability and lifetime of the synchronous states. Using\nholographic optical tweezers we quantitatively verify our predictions in a\nvariety of spatial configurations of rotors."
    },
    {
        "anchor": "Patterning of polar active filaments on a tense cylindrical membrane: We study the dynamics and patterning of polar contractile filaments on the\nsurface of a cylindrical cell using active hydrodynamic equations that\nincorporate couplings between curvature and filament orientation. Cables and\nrings spontaneously emerge as steady state configurations on the cylinder, and\ncan be stationary or moving, helical or segments moving along helical\ntrajectories. Contractility induces coalescence of proximal rings. We observe\nphase transitions in the steady state patterns upon changing cell diameter and\nmake several testable predictions. Our results are relevant to the dynamics and\npatterning of a variety of active biopolymers in cylindrical cells.",
        "positive": "Perspective: Mechanics of randomly packed filaments -- the `bird nest'\n  as meta-material: Systems of randomly packed, macroscopic elements, from jammed spherical\ngrains to tangled long filaments, represent a broad class of disordered\nmeta-materials with a wide range of applications and manifestations in nature.\nA `bird nest' presents itself at an interface between hard round grains\ndescribed by granular physics to long soft filaments, the center of textile\nmaterial science. All of these randomly packed systems exhibit forms of self\nassembly, evident through their robust packing statistics, and a common,\nunusual elastoplastic response to oedometric compression. In reviewing packing\nstatistics, mechanical response characterization and consideration of boundary\neffects, we present a perspective that attempts to establish a link between the\nbulk and local behaviour of a pile of sand and a wad of cotton, demonstrating\nthe nest's relationship with each. Finally, potential directions for impactful\napplications are outlined."
    },
    {
        "anchor": "Gas-filled pore in bounded particle: The diffusive evolution has been studied of gas-filled pore has in a bounded\nparticle in gas media. The nonlinear equation set, describing the behaviour of\ngas-filled pore on bounded particle is obtained. Asymptotic modes are\nconsidered for evolution of small and large pores. Analytical solutions are\nobtained in asymptotic modes. The comparison is conducted of these solutions\nwith results of numerical solution of complete equation set. The characteristic\nregularities of gas-filled pore behavior are found at arbitrary pore position\nrelative to matrix particle center.",
        "positive": "Encapsulation of DNA by cationic diblock copolymer vesicles: Encapsulation of dsDNA fragments (contour length 54 nm) by the cationic\ndiblock copolymer poly(butadiene-b-N-methyl 4-vinyl pyridinium) [PBd-b-P4VPQ]\nhas been studied with phase contrast, polarized light, and fluorescence\nmicroscopy, as well as scanning electron microscopy. Encapsulation was achieved\nwith a single emulsion technique. For this purpose, an aqueous DNA solution is\nemulsified in an organic solvent (toluene) and stabilized by the amphiphilic\ndiblock copolymer. The PBd block forms an interfacial brush, whereas the\ncationic P4VPQ block complexes with DNA. A subsequent change of the quality of\nthe organic solvent results in a collapse of the PBd brush and the formation of\na capsule. Inside the capsules, the DNA is compacted as shown by the appearance\nof birefringent textures under crossed polarizers and the increase in\nfluorescence intensity of labeled DNA. The capsules can also be dispersed in\naqueous medium to form vesicles, provided they are stabilized with an osmotic\nagent (polyethylene glycol) in the external phase. It is shown that the DNA is\nreleased from the vesicles once the osmotic pressure drops below 105 N/m2 or if\nthe ionic strength of the supporting medium exceeds 0.1 M. The method has also\nproven to be efficient to encapsulate pUC18 plasmid in sub-micron sized\nvesicles and the general applicability of the method has been demonstrated by\nthe preparation of the charge inverse system: cationic poly(ethylene imine)\nencapsulated by the anionic diblock poly(styrene-b-acrylic acid)."
    },
    {
        "anchor": "Topologically controlled emergent dynamics in flow networks: Flow networks are essential for both living organisms and enginneered\nsystems. These networks often present complex dynamics controlled, at least in\npart, by their topology. Previous works have shown that topologically complex\nnetworks interconnecting explicitly oscillatory or excitable elements can\ndisplay rich emerging dynamics. Here we present a model for complex flow\nnetworks with non-linear conductance that allows for internal\naccumulation/depletion of volume, without any inherent oscillatory or excitable\nbehavior at the nodes. In the absence of any time dependence in the pressure\ninput and output we observe emerging dynamics in the form of self-sustained\nwaves, which travel through the system. The frequency of these waves depends\nstrongly on the network architecture and it can be explained with a topological\nmetric.",
        "positive": "Decreasing critical temperature of gas BEC in spatially periodic\n  potential and relevance to experiments treated by Mott-Hubbard model: It is shown that the critical temperature of gas Bose-Einstein condensation\ndecreases in deepening periodic potential, in contrast to common regularity in\na separate potential well. The physical explanation of this phenomenon is\ngiven. Characteristic scale of potential energies decaying the critical\ntemperature is the quantum recoil energy of periodic potential. The theory\nrepresents an alternative and direct approach to the experimental results\n(C.Orzel et al Science 291, 2386 (2001); M.Greiner et al, Nature 415, 39\n(2002)) obtained with BEC in optical lattices and treated as the phase\nsqueezing or Mott transition processes."
    },
    {
        "anchor": "Orientational Order in the Nematic and Heliconical Nematic Liquid\n  Crystals: X-ray scattering and polarized microscopic studies of the structure and order\nparameters in the nematic (N) and heliconical, or the twist-bend nematic (Ntb),\nphase have been performed as a function of temperature. The nematic\norientational order parameters <P2(cos{\\theta})> and <P4(cos{\\theta})> in the\nnematic phases of CB7CB and its mixtures with less than 20 wt% CB6CB reveal\nthat they both increase with decreasing temperature in the N phase. Both order\nparameters decrease upon entering the Ntb phase and <P4(cos{\\theta})> becomes\nnegative providing a direct confirmation of the conical molecular orientational\ndistribution. The heliconical tilt angle, estimated from the orientational\ndistribution functions (ODFs), in all cases increases from zero at the N - Ntb\ntransition to approximately 27{\\deg} at about 40 K below the transition, in\nexcellent agreement with freeze fracture transmission electron microscopy\nresults of Chen and the birefringence results of Meyer. The growth of the tilt\nangle in the Ntb phase follows a single power law with exponents between ~0.09\n+/- 0.01 to -0.12 +/- 0.01, which is far from the expected tricritical or mean\nfield exponents of 0.25 or 0.5. The temperature dependence of the tilt angle\ncalculated from the ODFs also is in good qualitative agreement with the values\nestimated from optical studies of their ropelike textures within adjacent\nblocks of left- and right-handed twist in homogeneously aligned cells.",
        "positive": "Darcy's law of yield stress fluids on a treelike network: Understanding the flow of yield stress fluids in porous media is a major\nchallenge. In particular, experiments and extensive numerical simulations\nreport a non-linear Darcy law as a function of the pressure gradient. In this\nletter, we consider a tree-like porous structure for which the problem of the\nflow can be resolved exactly thanks to a mapping with the directed polymer (DP)\nwith disordered bond energies on the Cayley tree. Our results confirm the\nnon-linear behavior of the flow and expresses its full pressure-dependence via\nthe density of low-energy paths of DP restricted to vanishing overlap. These\nuniversal predictions are confirmed by extensive numerical simulations."
    },
    {
        "anchor": "Emergence of linear isotropic elasticity in amorphous and\n  polycrystalline materials: We investigate the emergence of isotropic linear elasticity in amorphous and\npolycrystalline solids, via extensive numerical simulations. We show that the\nelastic properties are correlated over a finite length scale $\\xi_E$, so that\nthe central limit theorem dictates the emergence of continuum linear isotropic\nelasticity on increasing the specimen size. The stiffness matrix of systems of\nfinite size $L > \\xi_E$ is obtained adding to that predicted by linear\nisotropic elasticity a random one of spectral norm $(L/\\xi_E)^{-3/2}$, in three\nspatial dimensions. We further demonstrate that the elastic length scale\ncorresponds to that of structural correlations, which in polycrystals reflect\nthe typical size of the grain boundaries and length scales characterizing\ncorrelations in the stress field. We finally demonstrate that the elastic\nlength scale affects the decay of the anisotropic long-ranged correlations of\nlocally defined shear modulus and shear stress.",
        "positive": "Deformation and dynamics of erythrocytes govern their traversal through\n  microfluidic devices with a deterministic lateral displacement architecture: Deterministic lateral displacement (DLD) microfluidic devices promise\nversatile and precise processing of biological samples. However, this prospect\nhas been realized so far only for rigid spherical particles and remains limited\nfor biological cells due to the complexity of cell dynamics and deformation in\nmicrofluidic flow. We employ mesoscopic hydrodynamics simulations of red blood\ncells (RBC) in DLD devices with circular posts to better understand the\ninterplay between cell behavior in complex microfluidic flow and sorting\ncapabilities of such devices. We construct a mode diagram of RBC behavior (e.g.\ndisplacement, zig-zagging, and intermediate modes) and identify several regimes\nof RBC dynamics (e.g. tumbling, tank-treading, and trilobe motion).\nFurthermore, we link the complex interaction dynamics of RBCs with the post to\ntheir effective cell size and discuss relevant physical mechanisms governing\nthe dynamic cell states. In conclusion, sorting of RBCs in DLD devices based on\ntheir shear elasticity is in general possible, but requires fine-tuning of flow\nconditions to targeted mechanical properties of the RBCs."
    },
    {
        "anchor": "Acoustically propelled nano- and microcones: fast forward and backward\n  motion: We focus on cone-shaped nano- and microparticles, which have recently been\nfound to show particularly strong propulsion when they are exposed to a\ntraveling ultrasound wave, and study based on direct acoustofluidic computer\nsimulations how their propulsion depends on the cones' aspect ratio. The\nsimulations reveal that the propulsion velocity and even its sign are very\nsensitive to the aspect ratio, where short particles move forward whereas\nelongated particles move backward. Furthermore, we identify a cone shape that\nallows for a particularly large propulsion speed. Our results contribute to the\nunderstanding of the propulsion of ultrasound-propelled colloidal particles,\nsuggest a method for separation and sorting of nano- and microcones concerning\ntheir aspect ratio, and provide useful guidance for future experiments and\napplications.",
        "positive": "A Molecular Theory for Liquid Crystal Elastomers: Nematic Ordering,\n  Shape Deformation and Mechanical Response: Modeling liquid crystal elastomers (LCEs) at the molecular level is crucial\nfor the predictable design of energy-conversion and stimuli-responsive\nmaterials. Here, we develop a self-consistent field theory for LCEs which\ncaptures the coupling between nematic ordering, backbone alignment and network\ndeformation. Molecular features such as density of elastic strands, strength\nand architecture of local chemical hinge, and LC grafting density are\nsystematically included. Crosslinking suppresses nematic ordering as a result\nof the elastic energy stored during network deformation. Higher work capacity\ncan be achieved by less crosslinked LCEs. The spontaneous shape change of\nend-on side-chain LCEs can be either elongation or contraction depending on the\ncompetition between the local and global couplings. Adjusting LC grafting\ndensity is found to be an effective way to fine-tune the deformation mode. We\nelucidate a universal scaling relationship between the transition temperature\nand the shear modulus as $T_{\\rm NI,0}-T_{\\rm NI}\\sim {\\mu^*}^{\\frac{4}{5}}$.\nFurthermore, we predict that the first-order nematic phase transition can be\ndegraded into a continuous manner upon applied stress. Coupled with nematic\nordering, the mechanical response of LCEs significantly deviates from classical\nrubber elasticity. A plateau in the stress-deformation curve appears\naccompanied by the nematic phase transition. Our theoretical predictions are in\ngood agreement with the experimental results reported in the literature."
    },
    {
        "anchor": "Fluctuations of ring polymers: We present an exact solution for the distribution of sample averaged monomer\nto monomer distance of ring polymers. For non-interacting and\nweakly-interacting models these distributions correspond to the distribution of\nthe area under the reflected Bessel bridge and the Bessel excursion\nrespectively, and are shown to be identical in dimension d greater or equal 2.\nA symmetry of the problem reveals that dimension d and 4 minus d are\nequivalent, thus the celebrated Airy distribution describing the areal\ndistribution of the one dimensional Brownian excursion describes also a polymer\nin three dimensions. For a self-avoiding polymer in dimension d we find\nnumerically that the fluctuations of the scaled averaged distance are nearly\nidentical in dimensions 2 and 3, and are well described to a first\napproximation by the non-interacting excursion model in dimension 5.",
        "positive": "Fluctuations in mixtures of lamellar- and nonlamellar-forming lipids: We consider the role of nonlamellar-forming lipids in biological membranes by\nexamining fluctuations, within the random phase approximation, of a model\nmixture of two lipids, one of which forms lamellar phases while the other forms\ninverted hexagonal phases. To determine the extent to which nonlamellar-forming\nlipids facilitiate the formation of nonlamellar structures in lipid mixtures,\nwe examine the fluctuation modes and various correlation functions in the\nlamellar phase of the mixture. To highlight the role fluctuations can play, we\nfocus on the lamellar phase near its limit of stability. Our results indicate\nthat in the initial stages of the transition, undulations appear in the\nlamellae occupied by the tails, and that the nonlamellar-forming lipid\ndominates these undulations. The lamellae occupied by the head groups pinch off\nto make the tubes of the hexagonal phase. Examination of different correlations\nand susceptibilities makes quantitative the dominant role of the\nnonlamellar-forming lipids."
    },
    {
        "anchor": "Jamming below upper critical dimension: Extensive numerical simulations in the past decades proved that the critical\nexponents of the jamming of frictionless spherical particles remain unchanged\nin two and three dimensions. This implies that the upper critical dimension is\n$d_u=2$ or lower. In this work, we study the jamming transition below the upper\ncritical dimension. We investigate a quasi-one-dimensional system: disks\nconfined in a narrow channel. We show that the system is isostatic at the\njamming transition point as in the case of standard jamming transition of the\nbulk systems in two and three dimensions. Nevertheless, the scaling of the\nexcess contact number shows the linear scaling. Furthermore, the gap\ndistribution remains finite even at the jamming transition point. These results\nare qualitatively different from those of the bulk systems in two and three\ndimensions.",
        "positive": "Multiple dynamic regimes in concentrated microgel systems: We investigate dynamical heterogeneities in the collective relaxation of a\nconcentrated microgel system, for which the packing fraction can be\nconveniently varied by changing the temperature. The packing fraction dependent\nmechanical properties are characterised by a fluid-solid transition, where the\nsystem properties switch from a viscous to an elastic low-frequency behaviour.\nApproaching this transition from below, we find that the range of spatial\ncorrelations in the dynamics increases. Beyond this transition, the spatial\ncorrelation range reaches a maximum, extending over the entire observable\nsystem size of approximately 5 mm. Increasing the packing fraction even further\nleads to a second transition, which is characterised by the development of\nlarge zones of lower and higher dynamical activity that are well separated from\neach other; the range of correlation decreases at this point. This striking\nnon-monotonic dependence of the spatial correlation length on volume fraction\nis reminiscent of the behaviour recently observed at the jamming/rigidity\ntransition in granular systems (Lechenault et al. 2008). We identify this\nsecond transition as the transition to 'squeezed' states, where the\nconstituents of the system start to exert direct contact forces on each other,\nsuch that the dynamics becomes increasingly determined by imbalanced stresses.\nEvidence of this transition is also found in the frequency dependence of the\nstorage and loss moduli, which become increasingly coupled as direct friction\nbetween the particles starts to contribute to the dissipative losses within the\nsystem. To our knowledge, our data provide the first observation of a\nqualitative change in dynamical heterogeneity as the dynamics switch from\npurely thermally-driven to stress-driven."
    },
    {
        "anchor": "Excitation spectrum of three dressed Bose-Einstein condensates: We study quantum dynamics of three dressed Bose-Einstein condensates in a\nhigh-Q cavity. The quasiparticle excitation spectrum of this system is found\nnumerically.\n  The stability of the quasiparticle excitation is analyzed. It is shown that\nthere exist instabilities in the excitation spectrum.",
        "positive": "Separation of suspended particles in microfluidic systems by\n  directional-locking in periodic fields: We investigate the transport and separation of overdamped particles under the\naction of a uniform external force in a two-dimensional periodic energy\nlandscape. Exact results are obtained for the deterministic transport in a\nsquare lattice of parabolic, repulsive centers that correspond to a\npiecewise-continuous linear-force model. The trajectories are periodic and\ncommensurate with the obstacle lattice and exhibit phase-locking behavior in\nthat the particle moves at the same average migration angle for a range of\norientation of the external force. The migration angle as a function of the\norientation of the external force has a Devil's staircase structure. The first\ntransition in the migration angle was analyzed in terms of a Poincare map,\nshowing that it corresponds to a tangent bifurcation. Numerical results show\nthat the limiting behavior for impenetrable obstacles is equivalent to the high\nPeclet number limit in the case of transport of particles in a periodic pattern\nof solid obstacles. Finally, we show how separation occurs in these systems\ndepending on the properties of the particles."
    },
    {
        "anchor": "Aging, rejuvenation and thixotropy in complex fluids. Time-dependence of\n  the viscosity at rest and under constant shear rate or shear stress: Complex fluids exhibit time-dependent changes in viscosity that have been\nascribed to both thixotropy and aging. However, there is no consensus for which\nphenomenon is the origin of which changes. A novel thixotropic model is defined\nthat incorporates aging. Conditions under which viscosity changes are due to\nthixotropy and aging are unambiguously defined. Viscosity changes in a complex\nfluid during a period of rest after destructuring exhibit a bifurcation at a\ncritical volume fraction PHIc2. For volume fractions less than PHIc2, the\nviscosity remains finite in the limit t => infinite. For volume fractions above\ncritical the viscosity grows without limit, so aging occurs at rest. At\nconstant shear rate there is no bifurcation, whereas under constant shear\nstress the model predicts a new bifurcation in the viscosity at a critical\nstress sB, identical to the yield stress sy observed under steady conditions.\nThe divergence of the viscosity for stress s sB is best defined as aging.\nHowever, for s > sB, where the viscosity remains finite, it seems preferable to\nuse the concepts of restructuring and destructuring, rather than aging and\nrejuvenation. Nevertheless, when a stress sA (sB) is applied during aging,\nslower aging is predicted and discussed as true rejuvenation. Plastic behaviour\nis predicted under steady conditions when s > sB. The Herschel-Bulkley model\nfits the flow curve for stresses close to sB, whereas the Bingham model gives a\nbetter fit for s >> sB. Finally, the model's predictions are shown to be\nconsistent with experimental data from the literature for the transient\nbehaviour of laponite gels.",
        "positive": "Parallel tempering Monte Carlo simulations of spherical\n  fixed-connectivity model for polymerized membranes: We study the first order phase transition of the fixed-connectivity\ntriangulated surface model using the Parallel Tempering Monte Carlo (PTMC)\ntechnique on relatively large lattices. From the PTMC results, we find that the\ntransition is considerably stronger than the reported ones predicted by the\nconventional Metropolis MC (MMC) technique and the flat histogram MC technique.\nWe also confirm that the results of the PTMC on relatively smaller lattices are\nin good agreement with those known results. This implies that the PTMC is\nsuccessfully used to simulate the first order phase transitions. The parallel\ncomputation in the PTMC is implemented by OpenMP, where the speed of the PTMC\non multi-core CPUs is considerably faster than that on the single-core CPUs."
    },
    {
        "anchor": "Aspects of the density field in an active nematic: Active nematics are conceptually the simplest orientationally ordered phase\nof self-driven particles, but have proved to be a perennial source of\nsurprises. We show here through numerical solution of coarse-grained equations\nfor order parameter and density that the growth of the active nematic phase\nfrom the isotropic phase is necessarily accompanied by a clumping of the\ndensity. The growth kinetics of the density domains is shown to be faster than\nthe 1/3-law expected for variables governed by a conservation law. Other\nresults presented include the suppression of density fluctuations in the\nstationary ordered nematic by the imposition of an orienting field. We close by\nposing some open questions.",
        "positive": "Phase Separation and Coarsening in Electrostatically Driven Granular\n  Media: A continuum model for the phase separation and coarsening, observed in\nelectrostatically driven granular media, is formulated in terms of a\nGinzburg-Landau equation subject to conservation of the total number of grains.\nIn the regime of well-developed clusters, the continuum model is used to derive\n\"sharp-interface\" equations that govern the dynamics of the interphase\nboundary. The model captures the essential physics of this system."
    },
    {
        "anchor": "Describing the Flow Curve of Shear-Banding Fluids Through a Structural\n  Minimal Model: Main characteristics of colloidal systems that develop fluid phases with\ndifferent mechanical properties, namely shear-banding fluids, are briefly\nreviewed both from experimental and theoretical (modelling) point of view. A\nnon-monotonic shear stress vs. shear rate constitutive relation is presented.\nThis relation derives from a phenomenological model of a shear ratedependent\nviscosity describing structural changes and involves the possibility of\nmultivalued shear rates under a given shear stress. In the case of a\nstress-dependent viscosity, the same model allows one to predict vorticity\nbanding. Predictions of this model under controlled stress are discussed,\nnamely occurrence of a kind of top- and bottom-jumping of the shear rate in\nresponse to stress increasing-decreasing. Applying this model to evaluation of\nthe flow curve of such colloidal systems is performed. Particular emphasis is\nplaced on the adequate computation of the shear rate function in cylindrical\nCouette cells in order to handle the corresponding flow curve which exhibits\nthe well-known shear stress plateau. Indeed, as different fluid phases coexist\nin the flow domain, measured (torque vs. angular velocity) data cannot be\ndirectly converted into rheometric (shear stress vs. shear rate) functions. As\nthe lacking non-local terms in the model prevents the direct determination of\nthe stress-plateau, this value is included as an adjustable parameter. Thus\nmodel predictions satisfactorily match up experimental data of wormlike\nmicellar solutions from the literature.",
        "positive": "Phase Separation and Coexistence of Hydrodynamically Interacting\n  Microswimmers: A striking feature of the collective behavior of spherical microswimmers is\nthat for sufficiently strong self-propulsion they phase-separate into a dense\ncluster coexisting with a low-density dis- ordered surrounding. Extending our\nprevious work, we use the squirmer as a model swimmer and the particle-based\nsimulation method of multi-particle collision dynamics to explore the influence\nof hydrodynamics on their phase behavior in a quasi-two-dimensional geometry.\nThe coarsening dynamics towards the phase-separated state is diffusive in an\nintermediate time regime followed by a final ballistic compactification of the\ndense cluster. We determine the binodal lines in a phase diagram of P\\'eclet\nnumber versus density. Interestingly, the gas binodals are shifted to smaller\ndensities for increasing mean density or dense-cluster size, which we explain\nusing a recently introduced pressure balance [S. C. Takatori et al., Phys. Rev.\nLett. 113, 028103 (2014)] extended by a hydrodynamic contribution. Furthermore,\nwe find that for pushers and pullers the binodal line is shifted to larger\nP\\'eclet numbers compared to neutral squirmers. Finally, when lowering the\nP\\'eclet number, the dense phase transforms from a hexagonal \"solid\" to a\ndisordered \"fluid\" state."
    },
    {
        "anchor": "Structure of smectic defect cores: an X-ray study of 8CB liquid crystal\n  ultra-thin films: We study the structure of very thin liquid crystal films frustrated by\nantagonistic anchorings in the smectic phase. In a cylindrical geometry, the\nstructure is dominated by the defects for film thicknesses smaller than 150 nm\nand the detailed topology of the defects cores can be revealed by x-ray\ndiffraction. They appear to be split in half tube-shaped Rotating Grain\nBoundaries (RGB). We determine the RGB spatial extension and evaluate its\nenergy per unit line. Both are significantly larger than the ones usually\nproposed in the literature",
        "positive": "Theoretical calculation of the phase behavior of colloidal membranes: We formulate a density functional theory that describes the phase behavior of\nhard rods and depleting polymers, as realized in recent experiments on\nsuspensions of \\emph{fd} virus and non-adsorbing polymer. The theory predicts\nthe relative stability of nematic droplets, stacked smectic columns, and a\nrecently discovered phase of isolated monolayers of rods, or colloidal\nmembranes. We find that a minimum rod aspect ratio is required for stability of\ncolloidal membranes and that collective protrusion undulations are the dominant\neffect that stabilizes this phase. The theoretical predictions are shown to be\nqualitatively consistent with experimental and computational results."
    },
    {
        "anchor": "Yielding and flow in aggregated particulate suspensions: A simple and popular constitutive model used to describe the compressional\nstrength of a consolidating strongly cohesive particulate gel is tested further\nwith new experimental data. Strong cohesive particulate gels have variously\nbeen described as being ratchet (poro) elastic, on the one hand, and as having\na yield stress in compression, on the other, to the point where same groups of\nworkers have used both descriptions at one time or another. The dichotomy is\nreal though as such gels do show a hitherto somewhat puzzling elastic-plastic\nduality. This can be explained in part by the strong concentration dependence\nof the modulus since this leads to irreversible volumetric strain-hardening, in\neffect, the ratchet; but only in small part. The real problem seems to be that,\nuntil very recently, most work on consolidation has neglected what what\nMichaels and Bolger told us to do over 50 years ago, viz. to take into wall\nadhesion into account, most cohesive particulate gels being adhesive too. Since\nwall adhesive failure is plastic in character, the simplest non-linear elastic\nmodel of compressive strength can be combined with the simplest possible model\nof wall debonding to produce a approximate complete constitutive description.\nExamples of the use of such a description in detailed modelling of\nconsolidation equilibrium can be found in refs 10-12. Consolidation dynamics\nwith wall adhesion is a substantial modelling challenge remaining to be\ntackled.",
        "positive": "Effects of dimethyl sulfoxide on surface water near phospholipid\n  bilayers: Despite much effort to probe the properties of dimethyl sulfoxide (DMSO)\nsolution, effects of DMSO on water, especially near plasma membrane surfaces\nstill remain elusive. By performing molecular dynamics (MD) simulations at\nvarying DMSO concentrations ($X_{\\text{DMSO}}$), we study how DMSO affects\nstructural and dynamical properties of water in the vicinity of phospholipid\nbilayers. As proposed by a number of experiments, our simulations confirm that\nDMSO induces dehydration from bilayer surfaces and disrupts the H-bond\nstructure of water. However, DMSO enhanced water diffusivity at solvent-bilayer\ninterfaces, an intriguing discovery reported by a spin-label measurement, is\nnot confirmed in our simulations. In order to resolve this discrepancy, we\nexamine the location of the spin-label (Tempo), relative to the solvent-bilayer\ninterface. In accord with the evidence in the literature, our simulations,\nwhich explicitly model Tempo-PC, find that the Tempo moiety is equilibrated at\n$\\sim 8-10$ \\AA\\ \\emph{below} the bilayer surface. Furthermore, the\nDMSO-enhanced surface water diffusion is confirmed only when water diffusion is\nanalyzed around the Tempo moiety that is immersed below the bilayer surface,\nwhich implies that the experimentally detected signal of water using Tempo\nstems from the interior of bilayers, not from the interface. Our analysis finds\nthat the increase of water diffusion below the bilayer surface is coupled to\nthe increase of area per lipid with an increasing $X_{\\text{DMSO}}$ $(\\lesssim\n10\\text{ mol\\%})$. Underscoring the hydrophobic nature of Tempo moiety, our\nstudy calls for careful re-evaluation of the use of Tempo in the measurement on\nlipid bilayer surfaces."
    },
    {
        "anchor": "Nonlinear mechanosensation in fiber networks: In a diversity of physiological contexts, eukaryotic cells adhere to an\nextracellular matrix (ECM), a disordered network with complex nonlinear\nmechanics. Such cells can perform mechanosensation: using local force probing\nthey can measure and respond to their substrate's mechanical properties. It\nremains unclear, however, how the mechanical complexity of the ECM at the\ncellular scale impacts mechanosensation. Here, we investigate the physical\nlimits of mechanosensation imposed by the inherent structural disorder and\nnonlinear elastic response of the ECM. Using a theoretical framework for\ndisordered fiber networks, we find that the extreme mechanical heterogeneity\nthat cells can locally sense with small probing forces is strongly reduced with\nincreasing force. Specifically, we predict that the accuracy of\nmechanosensation dramatically improves with force, following a universal power\nlaw insensitive to constitutive details, which we quantitatively confirm using\nmicrorheology experiments in collagen and fibrin gels. We provide conceptual\ninsights into this behavior by introducing a general model for nonlinear\nmechanosensation, based on the idea of an emergent nonlinear length-scale\nassociated with fiber buckling. This force-dependent length-scale enhances the\nrange over which local mechanical measurements are performed, thereby averaging\nthe response of a disordered network over an enlarged region. We show with an\nexample how a cell can use this nonlinear mechanosensation to infer the\nmacroscopic mechanical properties of a disordered ECM using local measurements.\nTogether, our results demonstrate that cells can take advantage of the inherent\nnonlinearity of fibrous networks to robustly sense, control, and respond to\ntheir mechanical environment.",
        "positive": "Taut-Line Buzzers with Periodic Forcing: The time-dependent forcing and work per cycle required to drive sinusoidal\nspinning of a taut-line buzzer is analytically derived, both on and off\nresonance, from the nonlinear equation of motion. To test predictions, a model\nexperimental system is constructed and characterized in terms of contraction\nversus twist angle and damped oscillations. The predicted force profile is then\napproximately implemented by hand. Nearly sinusoidal motion is observed, and\nthe energy injection per cycle needed to maintain steady state oscillations is\nfound to agree with theory. Additional force profiles are implemented, one to\nmaximize non-sinusoidal response and one to maximize the response per operator\neffort. With the latter, an Aluminum disk of radius 5~cm and height 0.95~cm was\nspun at a peak speed of over 11,000~RMP for fifteen minutes. The corresponding\nhand-powered centrifuge system would required $1.5\\times$ more force, twice the\npower, and triple the time in order to run $90\\times$ more samples than prior\nstate-of-art."
    },
    {
        "anchor": "A modified Poisson-Boltzmann theory: Effects of co-solvent\n  polarizability: In this paper within a field-theoretical approach taking into account\nexplicitly a co-solvent with a nonzero dipole and a polarizability tensor, we\nderive a modified Poisson-Boltzmann equation. Applying the modified\nPoisson-Boltzmann equation, we formulate a generalized Gouy-Chapman theory for\nthe case when an electrolyte solution is mixed with a polar co-solvent having a\nlarge polarizability. We show that an increase of the co-solvent concentration\nas well as the co-solvent polarizability lead to a significant increase of\ndifferential capacitance at sufficiently high surface potentials of the\nelectrode, whereas the profile of the electrostatic potential becomes\nconsiderably more long-ranged. On the contrary, an increase in the permanent\ndipole of the co-solvent only weakly affects the differential capacitance.",
        "positive": "Internal Avalanches in a Granular Medium: Avalanches of grain displacements can be generated by creating local voids\nwithin the interior of a granular material at rest in a bin. Modeling such a\ntwo-dimensional granular system by a collection of mono-disperse discs, the\nsystem on repeated perturbations, shows all signatures of Self-Organized\nCriticality. During the propagation of avalanches the competition among grains\ncreates arches and in the critical state a distribution of arches of different\nsizes is obtained. Using a cellular automata model we demonstrate that the\nexistence of arches determines the universal behaviour of the model system."
    },
    {
        "anchor": "Molecular dynamics of n-hexane: A quasi-elastic neutron scattering study\n  on the bulk and spatially nanochannel-confined liquid: We present incoherent quasi-elastic neutron scattering measurements in a\nwavevector transfer range from 0.4 AA^{-1} to 1.6AA^{-1} on liquid n-hexane\nconfined in cylindrical, parallel-aligned nanochannels of 6 nm mean diameter\nand 260 micrometer length in monolithic, mesoporous silicon. They are\ncomplemented with, and compared to, measurements on the bulk system in a\ntemperature range from 50K to 250K. The time-of-flight spectra of the bulk\nliquid can be modeled by microscopic translational as well as fast localized\nrotational, thermally-excited, stochastic motions of the molecules. In the\nnano-confined state of the liquid, which was prepared by vapor condensation, we\nfind two molecular populations with distinct dynamics, a fraction which is\nimmobile on the time scale of 1ps to 100ps probed in our experiments and a\nsecond component with a self-diffusion dynamics slightly slower than observed\nfor the bulk liquid. No hints of an anisotropy of the translational diffusion\nwith regard to the orientation of the channels' long axes have been found. The\nimmobile fraction amounts to about 5% at 250K, gradually increases upon cooling\nand exhibits an abrupt increase at 160K (20K below bulk crystallization), which\nindicates pore freezing",
        "positive": "Role of External Flow and Frame Invariance in Stochastic Thermodynamics: For configurational changes of soft matter systems affected or caused by\nexternal hydrodynamic flow, we identify applied work, exchanged heat, and\nentropy change on the level of a single trajectory. These expressions guarantee\ninvariance of stochastic thermodynamics under a change of frame of reference.\nAs criterion for equilibrium \\textit{vs.} nonequilibrium, zero \\textit{vs.}\nnonzero applied work replaces detailed balance \\textit{vs.} nonvanishing\ncurrents, since both latter criteria are shown to depend on the frame of\nreference. Our results are illustrated quantitatively by calculating the large\ndeviation function for the entropy production of a dumbbell in shear flow."
    },
    {
        "anchor": "Active forces in confluent cell monolayers: We use a computational phase-field model together with analytical analysis to\nstudy how inter-cellular active forces can mediate individual cell morphology\nand collective motion in a confluent cell monolayer. Contractile inter-cellular\ninteractions lead to cell elongation, nematic ordering and active turbulence,\ncharacterised by motile topological defects. Extensile interactions result in\nfrustration, and perpendicular cell orientations become more prevalent.\nFurthermore, we show that contractile behaviour can change to extensile\nbehaviour if anisotropic fluctuations in cell shape are considered.",
        "positive": "Interplay between freezing and density anomaly in a confined\n  core-softened system: We present a computer simulation study of influence of the confinement on the\ndensity anomaly in the system with isotropic core-softened potential which is\nused for a qualitative description of the anomalous behavior of water and some\nother liquids. We have found that a maximum temperature of the density anomaly\nregion along an isochor $\\rho=0.5$ does not depend on the pore width. We have\nshown that a decrease in the width of the confining slit pore leads to an\nincrease in the crystallization temperature and as a result the local density\ndistribution is mostly controlled by the particle-wall interaction, which leads\nto the depression of the density anomaly."
    },
    {
        "anchor": "Correlated local bending of DNA double helix and its effect on the\n  cyclization of short DNA fragments: We report a theoretical study of DNA flexibility and quantitatively predict\nthe ring closure probability as a function of DNA contour length. Recent\nexperimental studies show that the flexibility of short DNA fragments (as\ncompared to the persistence length of DNA l_P~150 base pairs) cannot be\ndescribed by the traditional worm-like chain (WLC) model, e.g., the observed\nring closure probability is much higher than predicted. To explain these\nobservations, DNA flexibility is investigated with explicit considerations of a\nnew length scale l_D~10 base pairs, over which DNA local bend angles are\ncorrelated. In this correlated worm-like chain (C-WLC) model, a finite length\ncorrection term is analytically derived and the persistence length is found to\nbe contour length dependent. While our model reduces to the traditional\nworm-like chain model when treating long DNA at length scales much larger than\nl_P, it predicts that DNA becomes much more flexible at shorter sizes, which\nhelps explain recent cyclization measurements of short DNA fragments around 100\nbase pairs.",
        "positive": "Active Nematic Multipoles: Flow Responses and the Dynamics of Defects\n  and Colloids: We introduce a general description of localised distortions in active\nnematics using the framework of active nematic multipoles. We give the\nStokesian flows for arbitrary multipoles in terms of differentiation of a\nfundamental flow response and describe them explicitly up to quadrupole order.\nWe also present the response in terms of the net active force and torque\nassociated to the multipole. This allows the identification of the dipolar and\nquadrupolar distortions that generate self-propulsion and self-rotation\nrespectively and serves as a guide for the design of arbitrary flow responses.\nOur results can be applied to both defect loops in three-dimensional active\nnematics and to systems with colloidal inclusions. They reveal the\ngeometry-dependence of the self-dynamics of defect loops and provide insights\ninto how colloids might be designed to achieve propulsive or rotational\ndynamics, and more generally for the extraction of work from active nematics.\nFinally, we extend our analysis also to two dimensions and to systems with\nchiral active stresses."
    },
    {
        "anchor": "Fine topological structure of coherent complex light created by carbon\n  nanocomposites in LC: Fine complex light structure, optical singularities and electroconductivty of\nnematic 5CB doped by multi-walled carbon nanotubes (MWCNTs) were investigated.\nMWCNTs gather spontaneously to system of micro scale clusters with random\nfractal borders at small enough concentration. They are surrounded by the\nstriped micro scale cladding which creates optical singularities in propagating\nlaser beam. Applied transverse electric field above the Freedericksz initiates\nhomeotropic arrangement of 5CB and the striped inversion walls between\nnanotubes clusters what diminishes free energy of a composite. Theory of their\nappearance and properties was built. Simultaneously the striped cladding\ndisappears what can be treated as new mechanism of structure orientation\nnonlinearity in nonlinear photonics. Polarization singularities (circular C\npoints) were measured firstly. Percolation of clusters enhances strongly\nelectrical conductivity of the system and creates inversion walls even without\napplied field. Carbon nanotubes composites in LC form bridge between nano\ndopants and micro/macro system and are promising for applications. Elaborated\nprotocol of singular optics inspection and characterization of LC\nnanocomposites is promising tool for applications in modern nanosience and\ntechnique.",
        "positive": "Shear-banding instability in arbitrarily inelastic granular shear flows: One prototypical instability in granular flows is the shear-banding\ninstability, in which a uniform granular shear flow breaks into alternating\nbands of dense and dilute clusters of particles having low and high shear\n(shear stress or shear rate), respectively. In this work, the shear-banding\ninstability in an arbitrarily inelastic granular shear flow is analyzed through\nthe linear stability analysis of granular hydrodynamic equations closed with\nNavier--Stokes-level constitutive relations. It is shown that the choice of\nappropriate constitutive relations plays an important role in predicting the\nshear-banding instability. A parametric study is carried out to study the\neffect of the restitution coefficient, channel width and mean density. Two\nglobal criteria relating the control parameters are found for the onset of the\nshear-banding instability."
    },
    {
        "anchor": "The origin of interparticle potential of electrorheological fluids: The particles of electrorheological fluids can be modelled as dielectric\nspheres (DS) immersed in a continuum dielectric. When an external field is\napplied, polarization charges are induced on the surfaces of the spheres and\ncan be represented as point dipoles placed in the centres of the spheres. When\nthe DSs are close to each other, the induced charge distributions are distorted\nby the electric field of the neighbouring DSs. This is the origin of the\ninteraction potential between the DSs. The calculation of this energy is very\ntime consuming, therefore, the DS model cannot be used in molecular\nsimulations. In this paper, we show that the interaction between the point\ndipoles appropriately approximates the interaction of DSs. The polarizable\npoint dipole model provides better results, but this model is not pair-wise\nadditive, so it is not that practical in particle simulations.",
        "positive": "Ion Conductivity in Salt-Doped Polymers: Combined Effects of Temperature\n  and Salt Concentration: We construct a coarse-grained molecular dynamics model based on poly(ethylene\noxide) and lithium bis-(trifluoromethane)sulfonimide salt to examine the\ncombined effects of temperature and salt concentration on the transport\nproperties. Salt doping notably slows down the dynamics of polymer chains and\nreduces ion diffusivity, resulting in a glass transition temperature increase\nproportional to the salt concentration. The polymer diffusion is shown to be\nwell represented by a modified Vogel-Fulcher-Tamman (M-VFT) equation that\naccounts for both the temperature and salt concentration dependence.\nFurthermore, we find that at any temperature, the concentration dependence of\nthe conductivity is well described by the product of its infinite dilution\nvalue and a correction factor accounting for the reduced segmental mobility\nwith increasing salt concentration. These results highlight the important role\nof polymer segmental mobility in the salt concentration dependence of ionic\nconductivity for temperatures near and above the glass transition."
    },
    {
        "anchor": "Efficiency of magnetic hyperthermia in the presence of rotating and\n  static fields: Single-domain ferromagnetic nanoparticle systems can be used to transfer\nenergy from a time-dependent magnetic field into their environment. This local\nheat generation, i.e., magnetic hyperthermia, receives applications in cancer\ntherapy which requires the enhancement of the energy loss. A possible way to\nimprove the efficiency is to chose a proper type of applied field, e.g., a\nrotating instead of an oscillating one. The latter case is very well studied\nand there is an increasing interest in the literature to investigate the former\nalthough it is still unclear under which circumstances the rotating applied\nfield can be more favourable than the oscillating one. The goal of this work is\nto incorporate the presence of a static field and to perform a systematic study\nof the non-linear dynamics of the magnetisation in the framework of the\ndeterministic Landau-Lifshitz-Gilbert equation in order to calculate energy\nlosses. Two cases are considered: the static field is either assumed to be\nperpendicular to the plane of rotation or situated in the plane of rotation. In\nthe latter case a significant increase in the energy loss/cycle is observed if\nthe magnitudes of the static and the rotating fields have a certain ratio (e.g.\nit should be one for isotropic nanoparticles). It can be used to\n\"super-localise\" the heat transfer: in case of an inhomogeneous applied static\nfield, tissues are heated up only where the magnitudes of the static and\nrotating fields reach the required ratio.",
        "positive": "Manning free counterions fraction for a rod-like polyion - short DNA\n  fragments in very low salt: We quantified the Manning free (uncondensed) counterions fraction $\\theta$\nfor dilute solutions of rod-like polyions - 150bp DNA fragments, in very low\nsalt $<0.05$mM. Conductivity measurements of aqueous DNA solutions in the\nconcentration range $0.015\\leq c \\leq 8$~mM (bp) were complemented by\nfluorescence correlation spectroscopy (FCS) measurements of the DNA polyion\ndiffusion coefficient $D_p(c)$. We observed a crossover in the normalized\nconductivity $\\sigma(c)/c$ which nearly halved across $c=0.05-1$ mM range,\nwhile $D_p(c)$ remained rather constant, as we established by FCS. Analyzing\nthese data we extracted $\\theta(c)=0.30 - 0.45$, and taking the Manning\nasymmetry field effect on polyelectrolyte conductivity into account we got\n$\\theta(c)=0.40-0.60$. We relate the $\\theta(c)$ variation to gradual DNA\ndenaturation occuring, in the very low salt environment, with the decrease in\nDNA concentration itself. The extremes of the experimental $\\theta(c)$ range\noccur towards the highest, above 1 mM and the lowest, below 0.05 mM, DNA\nconcentrations, and correspond to the theoretical $\\theta$ values for dsDNA and\nssDNA, respectively. Therefore, we confirmed Manning condensation and\nconductivity models to be valuable in description of dilute solutions of\nrod-like polyions."
    },
    {
        "anchor": "Hydrodynamics of a Semipermeable Vesicle Under Flow and Confinement: Lipid bilayer membranes have a native (albeit small) permeability for water\nmolecules. Under an external load, provided that the bilayer structure stays\nintact and does not suffer from poration or rupture, a lipid membrane deforms\nand its water influx/efflux is often assumed negligible in the absence of\nosmolarity. In this work we use boundary integral simulations to investigate\nthe effects of water permeability on the vesicle hydrodynamics due to a\nmechanical load, such as the viscous stress from an external flow deforming a\nvesicle membrane in free space or pushing it through a confinement.\nIncorporating the membrane permeability into the framework of Helfrich free\nenergy for an inextensible, elastic membrane as a model for a semipermeable\nvesicle, we illustrate that, in the absence of an osmotic stress gradient, the\nsemipermeable vesicle is affected by water influx/efflux over a sufficiently\nlong time or under a strong confinement. Our simulations quantify the\nconditions for water permeation to be negligible in terms of the time scales,\nflow strength, and confinement. These results shed light on how microfluidic\nconfinement can be utilized to estimate membrane permeability.",
        "positive": "Stability of thin liquid films and sessile droplets under confinement: The stability of nonvolatile thin liquid films and of sessile droplets is\nstrongly affected by finite size effects. We analyze their stability within the\nframework of density functional theory using the sharp kink approximation,\ni.e., on the basis of an effective interface Hamiltonian. We show that finite\nsize effects suppress spinodal dewetting of films because it is driven by a\nlong-wavelength instability. Therefore nonvolatile films are stable if the\nsubstrate area is too small. Similarly, nonvolatile droplets connected to a\nwetting film become unstable if the substrate area is too large. This\ninstability of a nonvolatile sessile droplet turns out to be equivalent to the\ninstability of a volatile drop which can attain chemical equilibrium with its\nvapor."
    },
    {
        "anchor": "Nature of excitations and defects in structural glasses: The nature of defects in amorphous materials, analogous to vacancies and\ndislocations in crystals, remains elusive. Here we explore their nature in a\nthree-dimensional microscopic model glass-former which describes granular,\ncolloidal, atomic and molecular glasses by changing the temperature and\ndensity. We find that all glasses evolve in a very rough energy landscape, with\na hierarchy of barrier sizes corresponding to both localized and delocalized\nexcitations. Collective excitations dominate in the jamming regime relevant for\ngranular and colloidal glasses. By moving gradually to larger densities\ndescribing atomic and molecular glasses, the system crosses over to a regime\ndominated by localized defects and relatively simpler landscapes. We quantify\nthe energy and temperature scales associated to these defects and their\nevolution with density. Our result pave the way to a systematic study of\nlow-temperature physics in a broad range of physical conditions and glassy\nmaterials.",
        "positive": "Minimal Coarse-Grained Modelling Towards Implicit-Solvent Simulation of\n  Generic Bolaamphiphiles: A simple, dual-site model of bolaamphiphiles (bolaforms or bipolar\namphiphiles) is developed based on an earlier single-site model of (monopolar)\namphiphiles [S. Dey, J. Saha, Phys. Rev. E 95, 023315 (2017)]. The model\nincorporates aqueous environment (both hydrophobic effect and hydration force)\nin its anisotropic site-site interactions, thus obviating the need to simulate\nsolvent particles explicitly. This economy of sites and the absence of explicit\nsolvent particles enable molecular dynamics simulations of bolaamphiphiles to\nachieve mesoscopic length and time-scales unattainable by any bead-spring model\nor explicit solvent computations. The model applies to generic bolas only,\nsince the gain in scale can only be obtained by sacrificing the resolution of\ndetailed molecular structure. Thanks to dual-sites, however, (as opposed to a\nsingle-site model) our model can incorporate the essential flexibility of bolas\nthat leads to their U-conformers. The model bolas show successful self-assembly\ninto experimentally observed nano-structures like micelles, rods, lamellae etc.\nand retain fluidity in very stable monolayers. Presence of membrane-spanning\nmodel bolas in bilayers of model monopolar amphiphiles increases the stability\nand impermeability of the lamellar phase. Model bolas are also seen to be less\ndiffusive and to produce thicker layers compared to their monopolar\ncounterparts. Rigid model bolas, though achiral themselves, show self-assembly\ninto helical rods. As all these observations agree with the well-known key\ncharacteristics of archaeal lipids and synthetic bolaamphiphiles, our model\npromises to be effective for studies of bolas in context of biomimetics,\ndrug-delivery and low molecular weight hydrogelators. To the best of our\nknowledge, no other single or dual-site, solvent-free model for bolas has been\nreported thus far."
    },
    {
        "anchor": "Exactness of the Annealed and the Replica Symmetric Approximations for\n  Random Heteropolymers: We study a heteropolymer model with random contact interactions introduced\nsome time ago as a simplified model for proteins. The model consists of\nself-avoiding walks on the simple cubic lattice, with contact interactions\nbetween nearest neighbor pairs. For each pair, the interaction energy is an\nindependent Gaussian variable with mean value $B$ and variance $\\D^2$. For this\nmodel the annealed approximation is expected to become exact for low disorder,\nat sufficiently high dimension and in the thermodynamic limit. We show that\ncorrections to the annealed approximation in the 3-d high temperature phase are\nsmall, but do not vanish in the thermodynamic limit, and are in good agreement\nwith our replica symmetric calculations. Such corrections derive from the fact\nthat the overlap between two typical chains is nonzero. We explain why previous\nauthors had come to the opposite conclusion, and discuss consequences for the\nthermodynamics of the model. Numerical results were obtained by simulating\nchains up to length 1400 by means of the recent PERM algorithm, in the coil and\nmolten globular phases, well above the freezing temperature.",
        "positive": "Entropy of water and the temperature-induced stiffening of amyloid\n  networks: In water, networks of semi-flexible fibrils of the protein $\\alpha$-synuclein\nstiffen significantly with increasing temperature. We make plausible that this\nreversible stiffening is a result of hydrophobic contacts between the fibrils\nthat become more prominent with increasing temperature. The good agreement of\nour experimentally observed temperature dependence of the storage modulus of\nthe network with a scaling theory linking network elasticity with reversible\ncrosslinking enables us to quantify the endothermic binding enthalpy and an\nestimate the effective size of hydrophobic patches on the fibril surface."
    },
    {
        "anchor": "Density functional theory for colloidal mixtures of hard platelets,\n  rods, and spheres: A geometry-based density functional theory is presented for mixtures of hard\nspheres, hard needles and hard platelets; both the needles and the platelets\nare taken to be of vanishing thickness. Geometrical weight functions that are\ncharacteristic for each species are given and it is shown how convolutions of\npairs of weight functions recover each Mayer bond of the ternary mixture and\nhence ensure the correct second virial expansion of the excess free energy\nfunctional. The case of sphere-platelet overlap relies on the same\napproximation as does Rosenfeld's functional for strictly two-dimensional hard\ndisks. We explicitly control contributions to the excess free energy that are\nof third order in density. Analytic expressions relevant for the application of\nthe theory to states with planar translational and cylindrical rotational\nsymmetry, e.g. to describe behavior at planar smooth walls, are given. For\nbinary sphere-platelet mixtures, in the appropriate limit of small platelet\ndensities, the theory differs from that used in a recent treatment [L. Harnau\nand S. Dietrich, Phys. Rev. E 71, 011504 (2004)]. As a test case of our\napproach we consider the isotropic-nematic bulk transition of pure hard\nplatelets, which we find to be weakly first order, with values for the\ncoexistence densities and the nematic order parameter that compare well with\nsimulation results.",
        "positive": "Hyper-sound as a means for generating inter-strand defects in a duplex\n  of the DNA: The formation of bubble defects of the double stranded DNA is treated\naccording to the Lifshits theory of disordered chains. A molecule of the DNA is\nmodelled on a harmonic lattice with nearest neighbour interaction, elastic\nconstants being randomly distributed. The helicoidal symmetry is accommodated\nthrough a chiral field at sites of the lattice. The number of sites varies from\n100 to 300, corresponding to DNA segmnets of persistence length. We find the\nspectra of elastic eigen-modes that mimic inter-strand excitations of the\nduplex. The frequency distribution shows peaks and valleys at the\nhigh-frequency end of the spectra, in accord with the general theory. External\nexcitations may lead to a parametric resonance that can generate localized\nmodes of the lattice. In real life pumping hyper-sound may generate a resonance\nsimilar to that studied in this paper, and thus result in excitation of\ninter-strand modes and possible formation of bubbles, in the duplex of the DNA."
    },
    {
        "anchor": "A dynamic jamming point for shear thickening suspensions: We report on rheometry measurements to characterize critical behavior in two\nmodel shear thickening suspensions: cornstarch in water and glass spheres in\noil. The slope of the shear thickening part of the viscosity curve is found to\nincrease dramatically with packing fraction and diverge at a critical packing\nfraction phi_c. The magnitude of the viscosity and the yield stress are also\nfound to have scalings that diverge at phi_c. We observe shear thickening as\nlong as the yield stress is less than the stress at the viscosity maximum.\nAbove this point the suspensions transition to purely shear thinning. Based on\nthese data we present a dynamic jamming phase diagram for suspensions and show\nthat a limiting case of shear thickening corresponds to a jammed state.",
        "positive": "Non-diffusive dynamics in a colloidal glass: aging versus rejuvenation: The microscopic dynamics of spontaneously aged and rejuvenated glassy\nLaponite is investigated through X-ray photon correlation spectroscopy. Two\ndifferent behaviours of the intensity autocorrelation functions are observed\ndepending on the history of the sample: stretched for spontaneously aged\nsamples and samples rejuvenated from a Wigner glass and compressed, typical of\nanomalous dynamics, for samples rejuvenated from a DHOC glass. The relaxation\ntime behaviour in the three cases indicates a non-diffusive dynamics of the\nparticles. The present system offers therefore an overview of various dynamical\nbehaviours previously observed individually in several systems and the\npossibility to pass from one to the other choosing ad hoc the time parameter."
    },
    {
        "anchor": "Diffusiophoretic Self-Propulsion for Partially Catalytic Spherical\n  Colloids: Colloidal spheres with a partial platinum surface coating perform\nauto-phoretic motion when suspended in hydrogen peroxide solution. We present a\ntheoretical analysis of the self-propulsion velocity of these particles using a\ncontinuum multi-component, self-diffusiophoretic model. With this model as a\nbasis, we show how the slip-layer approximation can be derived and in which\nlimits it holds. First, we consider the differences between the full\nmulti-component model and the slip-layer approximation. Then the slip model is\nused to demonstrate and explore the sensitive nature of the particle's velocity\non the details of the molecule-surface interaction. We find a strong asymmetry\nin the dependence of the colloid's velocity as a function of the level of\ncatalytic coating, when there is a different interaction between the solute and\nsolvent molecules and the inert and catalytic part of the colloid,\nrespectively. The direction of motion can even be reversed by varying the level\nof the catalytic coating. Finally, we investigate the robustness of these\nresults with respect to variations in the reaction rate near the edge between\nthe catalytic and inert parts of the particle. Our results are of significant\ninterest to the interpretation of experimental results on the motion of\nself-propelled particles.",
        "positive": "On the equivalence of the freely cooling granular gas to the sticky gas: A freely cooling granular gas with velocity dependent restitution coefficient\nis studied in one dimension. The restitution coefficient becomes near elastic\nwhen the relative velocity of the colliding particles is less than a velocity\nscale $\\delta$. Different statistical quantities namely density distribution,\noccupied and empty cluster length distributions, and spatial density and\nvelocity correlation functions, are obtained using event driven molecular\ndynamic simulations. We compare these with the corresponding quantities of the\nsticky gas (inelastic gas with zero coefficient of restitution). We find that\nin the inhomogeneous cooling regime, for times smaller than a crossover time\n$t_1$ where $t_1 \\sim \\delta^{-1}$, the behaviour of the granular gas is\nequivalent to that of the sticky gas. When $\\delta \\rt 0$, then $t_1 \\rt\n\\infty$ and hence, the results support an earlier claim that the freely cooling\ninelastic gas is described by the inviscid Burgers equation. For a real\ngranular gas with finite $\\delta$, the existence of the time scale $t_1$ shows\nthat, for large times, the granular gas is not described by the inviscid\nBurgers equation."
    },
    {
        "anchor": "Explicit secular equations for piezoacoustic surface waves: Rayleigh\n  modes: The existence of a two-partial Rayleigh wave coupled to an electrical field\nin 2mm piezoelectric crystals is known but has rarely been investigated\nanalytically. It turns out that the Z-cut, X-propagation problem can be fully\nsolved, up to the derivation of the secular equation as a polynomial in the\nsquared wave speed. For the metallized (unmetallized) boundary condition, the\npolynomial is of degree 10 (48). The relevant root is readily identified and\nthe full description of the mechanical and electrical fields follows. The\nresults are illustrated in the case of the superstrong piezoelectric crystal,\nPotassium niobate, for which the effective piezoelectric coupling coefficient\nis calculated to be about 0.1",
        "positive": "Large Amplitude Oscillatory Shear Study of a Colloidal Gel at the\n  Critical State: We investigate the nonlinear viscoelastic behavior of a colloidal dispersion\nat the critical gel state using large amplitude oscillatory shear (LAOS)\nrheology. The colloidal gel at the critical point is subjected to oscillatory\nshear flow with increasing strain amplitude at different frequencies. We\nobserve that the first harmonic of the elastic and viscous moduli exhibits a\nmonotonic decrease as the material undergoes a linear to nonlinear transition.\nWe analyze the stress waveform across this transition and obtain the nonlinear\nmoduli and viscosity as a function of frequency and strain amplitude. The\nanalysis of the nonlinear moduli and viscosities suggests intracycle strain\nstiffening and intracycle shear thinning in the colloidal dispersion. Based on\nthe insights obtained from the nonlinear analysis, we propose a potential\nscenario of the microstructural changes occurring in the nonlinear region. We\nalso develop an integral model using the time-strain separable K-BKZ\nconstitutive equation with a power-law relaxation modulus and damping function\nobtained from experiments. At low strain amplitudes, this model compares well\nwith experimental data at all frequencies. However, a stronger damping\nfunction, which can be efficiently inferred using a spectral method, is\nrequired to obtain quantitative fits across the entire range of strain\namplitudes and the explored frequencies."
    },
    {
        "anchor": "Dynamics of bacterial aggregates in microflows: Biofilms are bacterial aggregates that grow on moist surfaces. Thin\nhomogeneous biofilms naturally formed on the walls of conducts may serve as\nbiosensors, providing information on the status of microsystems (MEMS) without\ndisrupting them. However, uncontrolled biofilm growth may largely disturb the\nenvironment they develop in, increasing the drag and clogging the tubes. To\nensure controlled biofilm expansion we need to understand the effect of\nexternal variables on their structure. We formulate a hybrid model for the\ncomputational study of biofilms growing in laminar microflows. Biomass evolves\naccording to stochastic rules for adhesion, erosion and motion, informed by\nnumerical approximations of the flow fields at each stage. The model is tested\nstudying the formation of streamers in three dimensional corner flows, gaining\nsome insight on the effect of external variables on their structure.",
        "positive": "Secondary polygonal instability of buckled spherical shells: When a spherical elastic capsule is deflated, it first buckles\naxisymmetrically and subsequently loses its axisymmetry in a secondary\ninstability, where the dimple acquires a polygonal shape. We explain this\nsecondary polygonal buckling in terms of wrinkles developing at the inner side\nof the dimple edge in response to compressive hoop stress. Analyzing the\naxisymmetric buckled shape, we find a compressive hoop stress with parabolic\nstress profile at the dimple edge. We further show that there exists a critical\nvalue for this hoop stress, where it becomes favorable for the membrane to\nbuckle out of its axisymmetric shape, thus releasing the compression. The\ninstability mechanism is analogous to the formation of wrinkles under\ncompressive stress. A simplified stability analysis allows us to quantify the\ncritical stress for secondary buckling. Applying this secondary buckling\ncriterion to the axisymmetric shapes, we can determine the critical volume for\nsecondary buckling. Our analytical result is in close agreement with existing\nnumerical data."
    },
    {
        "anchor": "Physical ageing studied by a device allowing for rapid thermal\n  equilibration: Ageing of organic glasses to the equilibrium liquid state is studied by\nmeasuring the dielectric loss utilizing a microregulator where temperature is\ncontrolled by means of a Peltier element. Compared to conventional equipment\nthe new device adds almost two orders of magnitude to the span of observable\nageing times. Data for five organic glass-forming liquids are presented. The\nexistence of an \"inner clock\" is confirmed by a model-free test showing that\nthe ageing of structure is controlled by the same material time that controls\nthe dielectric properties. At long times relaxation is not stretched, but\nsimple exponential, and there is no \"expansion gap\" between the limits of the\nrelaxation rates following up and down jumps to the same temperature.",
        "positive": "Thermodynamics of Superfluidity: New, superfluid specific additive integral of motion is found. This\nfacilitates investigation of general thermodynamic equilibrium conditions for\nsuperfluid. The analysis is performed in an extended space of thermodynamic\nvariables containing (along with the usual thermodynamic coordinates such as\npressure and temperature) superfluid velocity and momentum density. The\nequilibrium stability conditions lead to thermodynamic inequalities which\nreplace the Landau superfluidity criterion at finite temperatures."
    },
    {
        "anchor": "Vibrational and acoustical properties of a liquid drop in the\n  phase-separated fluid with a highly mobile interface: We study the oscillation spectrum and acoustic properties of a liquid drop in\nthe phase-separated fluid when the interfacial dynamics of phase conversion can\nbe described in terms of the kinetic growth coefficient. For a readily mobile\ninterface, i.e., as the growth coefficient becomes comparable with a reciprocal\nof the acoustic impedance, anomalous behavior is found in the oscillation\nspectrum of a drop as well as in the velocity and absorption of a sound wave\npropagating through a suspension of drops in the two-phase system. Compared\nwith the known case of two immiscible fluids, the high interface mobility leads\nto an anomalous softening of the radial drop pulsations and to the frequency-\nand temperature-dependent behavior for the sound velocity and absorption\ncoefficient in a two-phase suspension.",
        "positive": "Arrested coalescence of multicellular aggregates: Multicellular aggregates are known to exhibit liquid-like properties. The\nfusion process of two cell aggregates is commonly studied as the coalescence of\ntwo viscous drops. However, tissues are complex materials and can exhibit\nviscoelastic behaviour. It is known that elastic effects can prevent the\ncomplete fusion of two drops, a phenomenon known as arrested coalescence. Here\nwe report the presence of this phenomenon in stem cell aggregates and provide a\ntheoretical framework which agrees with the experiments. In addition,\nagent-based simulations show that cell protrusion activity controls a\nsolid-to-fluid phase transition, revealing that arrested coalescence can be\nfound in the vicinity of an unjamming transition. By analysing the dynamics of\nthe fusion process and combining it with nanoindentation measurements, we\nobtain the effective viscosity, shear modulus and surface tension of the\naggregates. More generally, our work provides a simple, fast and inexpensive\nmethod to characterize the mechanical properties of viscoelastic materials."
    },
    {
        "anchor": "Surface modes and vortex formation in dilute Bose-Einstein condensates\n  at finite temperatures: The surface mode spectrum is computed self-consistently for dilute\nBose-Einstein condensates, providing the temperature dependence of the surface\nmode induced vortex nucleation frequency. Both the thermodynamic critical\nfrequency for vortex stability and the nucleation frequency implied by the\nsurface excitations increase as the critical condensation temperature is\napproached from below. The multipolarity of the destabilizing surface\nexcitation decreases with increasing temperature. The computed\nfinite-temperature critical frequencies support the experimental observations\nand the zero-temperature calculations for vortex nucleation.",
        "positive": "Adhesion of membranes with competing specific and generic interactions: Biomimetic membranes in contact with a planar substrate or a second membrane\nare studied theoretically. The membranes contain specific adhesion molecules\n(stickers) which are attracted by the second surface. In the absence of\nstickers, the trans--interaction between the membrane and the second surface is\nassumed to be repulsive at short separations. It is shown that the interplay of\nspecific attractive and generic repulsive interactions can lead to the\nformation of a potential barrier. This barrier induces a line tension between\nbound and unbound membrane segments which results in lateral phase separation\nduring adhesion. The mechanism for adhesion--induced phase separation is rather\ngeneral, as is demonstrated by considering two distinct cases involving: (i)\nstickers with a linear attractive potential, and (ii) stickers with a\nshort--ranged square--well potential. In both cases, membrane fluctuations\nreduce the potential barrier and, therefore, decrease the tendency of phase\nseparation."
    },
    {
        "anchor": "Analysis by the Two-Fluids Model of the Dynamical Behavior of a\n  Viscoelastic Fluid Probed by Dynamic Light Scattering: The dynamic properties of a model transient network have been studied by\ndynamic light scattering. The network is formed by microemulsion droplets\nlinked by telechelic polymers (modified hydrophilic polymers with two grafted\nhydrophobic stickers). We compare the properties of two networks that are\nsimilar but for the residence time of the hydrophobic stickers in the droplets.\nThe results are interpreted according to the so-called two-fluids model, which\nwas initially developed for semidilute polymer solutions and which we extend\nhere to any Maxwellian viscoelastic medium characterized by its elastic modulus\nand terminal time as measured by rheology. This model is found to describe\nconsistently and quantitatively the experimental observations.",
        "positive": "Chain Length Dependence on Folding Transition of a Semiflexible\n  Homo-polymer Chain: Appearance of a Core-Shell Structure: The folding transition of single, long semiflexible polymers was studied with\nspecial emphasis on the chain length effect using Monte Carlo simulations.\nWhile a relatively short chain (10-25 Kuhn segments) undergoes a large discrete\ntransiton between swollen coil and compact toroid conformations, a long chain\n(50 Kuhn segments) exhibits an intrachain segregated state between the\ndisordered coil and ordered toroid."
    },
    {
        "anchor": "Active Brownian particles and run-and-tumble particles separate inside a\n  maze: A diverse range of natural and artificial self-propelled particles are known\nand are used nowadays. Among them, active Brownian particles (ABPs) and\nrun-and-tumble particles (RTPs) are two important classes. We numerically study\nnon-interacting ABPs and RTPs strongly confined to different maze geometries in\ntwo dimensions. We demonstrate that by means of geometrical confinement alone,\nABPs are separable from RTPs. By investigating Matryoshka-like mazes with\nnested shells, we show that a circular maze has the best filtration efficiency.\nResults on the mean first-passage time reveal that ABPs escape faster from the\ncenter of the maze, while RTPs reach the center from the rim more easily.\nAccording to our simulations and a rate theory, which we developed, ABPs in\nsteady state accumulate in the outermost region of the Matryoshka-like mazes,\nwhile RTPs occupy all locations within the maze with nearly equal probability.\nThese results suggest a novel technique for separating different types of\nself-propelled particles by designing appropriate confining geometries without\nusing chemical or biological agents.",
        "positive": "Theoretical analysis of acoustic stop bands in two-dimensional periodic\n  scattering arrays: This paper presents a theoretical analysis of the recently reported\nobservation of acoustic stop bands in two-dimensional scattering arrays\n(Robertson and Rudy, J. Acoust. Soc. Am. {\\bf 104}, 694, 1998). A\nself-consistent wave scattering theory, incorporating all orders of multiple\nscattering, is used to obtain the wave transmission. The band structures for\nthe regular arrays of cylinders are computed using the plane wave expansion\nmethod. The theoretical results compare favorably with the experimental data."
    },
    {
        "anchor": "Photochemical-induced phase transitions in photoactive semicrystalline\n  polymers: The emergent photoactive materials through photochemistry make it possible to\ndirectly convert photon energy to mechanical work. There is much recent work in\ndeveloping appropriate materials and a promising new system is semi-crystalline\npolymers of the photoactive molecule azobenzene. We develop a phase field model\nwith two order parameters for the crystal-melt transition and the trans-cis\nphoto-isomerization to understand such materials, and the model describes the\nrich phenomenology. We find that the photo-reaction rate depends sensitively on\ntemperature: at temperatures below the crystal-melt transition temperature,\nphotoreaction is collective, requires a critical light intensity and shows an\nabrupt first order phase transition manifesting nucleation and growth; at\ntemperatures above the transition temperature, photoreaction is independent and\nfollows first order kinetics. Further, the phase transition depends\nsignificantly on the exact forms of spontaneous strain during the crystal-melt\nand trans-cis transitions. A non-monotonic change of photo-persistent cis ratio\nwith increasing temperature is observed accompanied by a reentrant\ncrystallization of trans below the melting temperature. A pseudo phase diagram\nis subsequently presented with varying temperature and light intensity along\nwith the resulting actuation strain. These insights can assist the further\ndevelopment of these materials.",
        "positive": "Sound absorption in glasses: The paper presents a description of the sound wave absorption in glasses,\nfrom the lowest temperatures up to the glass transition, in terms of three\ncompatible phenomenological models. Resonant tunneling, the rise of the\nrelaxational tunneling to the tunneling plateau and the crossover to classical\nrelaxation are universal features of glasses and are well described by the\ntunneling model and its extension to include soft vibrations and low barrier\nrelaxations, the soft potential model. Its further extension to non-universal\nfeatures at higher temperatures is the very flexible Gilroy-Phillips model,\nwhich allows to determine the barrier density of the energy landscape of the\nspecific glass from the frequency and temperature dependence of the sound wave\nabsorption in the classical relaxation domain. To apply it properly at elevated\ntemperatures, one needs its formulation in terms of the shear compliance. As\none approaches the glass transition, universality sets in again with an\nexponential rise of the barrier density reflecting the frozen fast Kohlrausch\nt^beta-tail (in time t, with beta close to 1/2) of the viscous flow at the\nglass temperature. The validity of the scheme is checked for literature data of\nseveral glasses and polymers with and without secondary relaxation peaks. The\nfrozen Kohlrausch tail of the mechanical relaxation shows no indication of the\nstrongly temperature-dependent barrier density observed in dielectric data of\nmolecular glasses with hydrogen bonds. Instead, the mechanical relaxation data\nindicate an energy landscape describable with a frozen temperature-independent\nbarrier density for any glass."
    },
    {
        "anchor": "Structure and stability of double emulsions: We propose diagrams representing the equilibrium morphologies of two\nimmiscible liquid droplets brought into contact. We study the dependence of the\nshape of the droplets on the surface tensions and ratio of volumes. We study\ntheoretically and experimentally the regimes of the parameters corresponding to\ncomplete engulfing (one of the droplets completely absorbed by the other one),\nnon-engulfing (in which the droplets remain separated) and partial-engulfing\n(intermediate configuration in which all three interfaces are present). We\nspecify the values of surface tensions corresponding to a Janus droplet, i.e.,\na perfectly spherical droplet composed of two sub-volumes occupied by two\ndifferent phases and separated by a curved interface. We further calculate and\nexperimentally verify a morphological transition between the states with\npositive and negative curvature of this interface depending on the ratio of\nvolumes and on the equilibrium contact angle.",
        "positive": "Universality in conformations and transverse fluctuations of a\n  semi-flexible polymer in a crowded environment: We study universal aspects of polymer conformations and transverse\nfluctuations for a single swollen chain characterized by a contour length $L$\nand a persistence length $\\ell_p$ in two dimensions (2D) and in three\ndimensions (3D) in the bulk, as well as in the presence of excluded volume (EV)\nparticles of different sizes occupying different volume fractions. In the\nabsence of the EV particles we extend the previously established universal\nscaling relations in 2D (A. Huang, A. Bhattacharya, and K. Binder, J. Chem.\n140, 214902 (2014)) to include 3D and demonstrate that the scaled end-to-end\ndistance $\\langle R_N^2\\rangle/(2 L\\ell_p)$ and the scaled transverse\nfluctuation $\\sqrt{\\langle{l_{\\perp}^2}\\rangle}/{L}$ as a function of\n$L/\\ell_p$ collapse onto the same master curve, where $\\langle R_N^2\\rangle$\nand $\\langle{l_{\\perp}^2\\rangle}$ are the mean-square end-to-end distance and\ntransverse fluctuations. However, unlike in 2D, where the Gaussian regime is\nabsent due to extreme dominance of the EV interaction, we find the Gaussian\nregime is present, albeit very narrow in 3D. The scaled transverse fluctuation\nin the limit $L/\\ell_p \\ll 1$ is independent of the physical dimension and\nscales as $\\sqrt{\\langle{l_{\\perp}^2}\\rangle}/{L} \\sim (L/\\ell_p)^{\\zeta-1}$,\nwhere $\\zeta = 1.5$ is the roughening exponent. For $L/\\ell_p \\gg 1$ the scaled\nfluctuation scales as $\\sqrt{\\langle{l_{\\perp}^2}\\rangle}/{L} \\sim\n(L/\\ell_p)^{\\nu-1}$, where $\\nu$ is Flory exponent for the corresponding\nspatial dimension ($\\nu_{2D}=0.75$, and $\\nu_{3D}=0.58$). When EV particles are\nadded into the system, our results indicate that the crowding density either\ndoes not or only weakly affects the universal scaling relations. We discuss the\nimplications of these results in living matter by showing the experimental\nresult for a dsDNA onto the master plot."
    },
    {
        "anchor": "Effective Temperatures of a Driven System Near Jamming: Fluctuations in a model of a sheared, zero-temperature foam are studied\nnumerically. Five different quantities that reduce to the true temperature in\nan equilibrium thermal system are calculated. All five have the same shear-rate\ndependence, and three have the same value. Near the onset of jamming, the\nrelaxation time is the same function of these three temperatures in the sheared\nsystem as of the true temperature in an unsheared system. These results imply\nthat statistical mechanics is useful for the system and provide strong support\nfor the concept of jamming.",
        "positive": "Decoupling the effects of shear and extensional flows on the alignment\n  of colloidal rods: Cellulose nanocrystals (CNC) can be considered as model colloidal rods and\nhave practical applications in the formation of soft materials with tailored\nanisotropy. Here, we employ two contrasting microfluidic devices to\nquantitatively elucidate the role of shearing and extensional flows on the\nalignment of a dilute CNC dispersion. Characterization of the flow field by\nmicro-particle image velocimetry is coupled to flow-induced birefringence\nanalysis to quantify the deformation rate--alignment relationship. The\ndeformation rate required for CNC alignment is 4$\\times$ smaller in extension\nthan in shear. Alignment in extension is independent of the deformation rate\nmagnitude, but is either 0$^\\circ$ or 90$^\\circ$ to the flow, depending on its\nsign. In shear flow the colloidal rods orientate progressively towards\n0$^\\circ$ as the deformation rate magnitude increases. Our results decouple the\neffects of shearing and extensional kinematics at aligning colloidal rods,\nestablishing coherent guidelines for the manufacture of structured soft\nmaterials."
    },
    {
        "anchor": "Disjoining Pressure and the Film-Height-Dependent Surface Tension of\n  Thin Liquid Films: New Insight from Capillary Wave Fluctuations: In this paper we review simulation and experimental studies of thermal\ncapillary wave fluctuations as an ideal means for probing the underlying\ndisjoining pressure and surface tensions, and more generally, fine details of\nthe Interfacial Hamiltonian Model. We discuss recent simulation results that\nreveal a film-height-dependent surface tension not accounted for in the\nclassical Interfacial Hamiltonian Model. We show how this observation may be\nexplained bottom-up from sound principles of statistical thermodynamics and\ndiscuss some of its implications.",
        "positive": "Colloidal transport in twisted lattices of optical tweezers: We simulate the transport of colloidal particles driven by a static and\nhomogeneous drift force, and subject to the optical potential created by two\nlattices of optical tweezers. The lattices of optical tweezers are parallel to\neach other, shifted, and rotated by a twist angle. Due to a negative\ninterference between the potential of the two lattices, flat channels appear in\nthe total optical potential. At specific twist angles, known as magic-angles,\nthe flat channels percolate the entire system and the colloidal particles can\nthen be transported using a weak external drift force. We characterize the\ntransport in both square and hexagonal lattices of twisted optical tweezers"
    },
    {
        "anchor": "Thermal expansion within a chain of magnetic colloidal particles: We study the thermal expansion of chains formed by self-assembly of magnetic\ncolloidal particles in a magnetic field. Using video-microscopy, complete\npositional data of all the particles of the chains is obtained. By changing the\nionic strength of the solution and the applied magnetic field, the interaction\npotential can be tuned. We analyze the thermal expansion of the chain using a\nsimple model of a one dimensional anharmonic crystal of finite size.",
        "positive": "Binary pusher-puller mixtures of active microswimmers and their\n  collective behavior: Microswimmers are active particles of microscopic size that self-propel by\nsetting the surrounding fluid into motion. According to the kind of far-field\nfluid flow that they induce, they are classified into pushers and pullers. Many\nstudies have explored similarities and differences between suspensions of\neither pushers or pullers, but the behavior of mixtures of the two is still to\nbe investigated. Here, we rely on a minimal discrete microswimmer model,\nparticle-resolved, including hydrodynamic interactions, to examine the\norientational ordering in such binary pusher-puller mixtures. In agreement with\nexisting literature, we find that our monodisperse suspensions of pushers do\nnot show alignment, whereas those of solely pullers spontaneously develop\nordered collective motion. By continuously varying the composition of the\nbinary mixtures, starting from pure puller systems, we find that ordered\ncollective motion is largely maintained up to pusher-puller composition ratios\nof about 1:2. Surprisingly, pushers when surrounded by a majority of pullers\nare more tightly aligned than indicated by the average overall orientational\norder in the system. Our study outlines how orientational order can be tuned in\nactive microswimmer suspensions to a requested degree by doping with other\nspecies."
    },
    {
        "anchor": "Dynamic Analysis of Confined Ionic Liquids and Ionic Magnetic Fluids:\n  Highlighting Long Range Elastic Interactions: By reinforcing the interaction energy of the liquid with respect to the\nsurface using total wetting boundary conditions, the response of liquids to\nmechanical shear stress is stronger and exhibits at sub-millimeter scale\nelastic properties. This study extends here to liquids with strong\nelectrostatic interactions such as ionic liquids and paramagnetic liquids. We\nshow that it is also possible to identify and measure a non-zero low-frequency\nshear elasticity at sub-millimeter scale. The observation of mesoscopic elastic\nproperties in liquids generally considered as viscous away from any phase\ntransition and the absence of extended structuring confirm the relevance of\nconsidering elastic interactions as contributing to collective effects under\nexternal electric or magnetic field.",
        "positive": "Optohydrodynamics of soft fluid interfaces : Optical and viscous\n  nonlinear effects: Recent experimental developments showed that the use of the radiation\npressure, induced by a continuous laser wave, to control fluid-fluid interface\ndeformations at the microscale, represents a very promising alternative to\nelectric or magnetic actuation. In this article, we solve numerically the\ndynamics and steady state of the fluid interface under the effects of buoyancy,\ncapillarity, optical radiation pressure and viscous stress. A precise\nquantitative validation is shown by comparison with experimental data. New\nresults due to the nonlinear dependence of the optical pressure on the angle of\nincidence are presented, showing different morphologies of the deformed\ninterface going from needle-like to finger-like shapes, depending on the\nrefractive index contrast. In the transient regime, we show that the viscosity\nratio influences the time taken for the deformation to reach steady state."
    },
    {
        "anchor": "Quasi-one dimensional degenerate Bose gas: Motivated by the MIT experiment [Gorlitz {\\em et al.}, Phys. Rev. Lett. {\\bf\n87}, 130402 (2001)], we analytically study the effect of density and phase\nfluctuations on various observables in a quasi one-dimensional degenerate Bose\ngases. Quantizing the Gross-Pitaevskii Hamiltonian and diagonalize it in terms\nof the normal modes associated with the density and phase fluctuations of a\nquasi-one dimensional Bose gas. We calculate dynamic structure factor\n$S(q,\\omega)$ from low-energy condensate density fluctuations and find that\nthere are multiple peaks in $S(q,\\omega)$ for a given momentum $q$ due to the\ndiscrete energy spectrum. These multiple peaks can be resolved by a two-photon\nBragg pulse with a long duration which transfer the momentum to the system. We\ncalculate the momentum transferred $ P_z(t)$ by using the phase-density\nrepresentation of the Bose order parameter. We also calculate the\nsingle-particle density matrix, phase coherence length, and momentum\ndistribution by taking care of the phase fluctuations upto fourth-order term as\nwell as the density fluctuations. Our studies on coherence properties shows\nthat 1D Bose gases of MIT experiment do not form a true condensate, but it can\nbe obtained by a moderate changes of the current experimental parameters.",
        "positive": "Effective interaction between star polymers: The distance-resolved effective interaction between two star polymers in a\ngood solvent is calculated by Molecular Dynamics computer simulations. The\nresults are compared with a pair potential proposed recently by Likos et al.\n[Phys. Rev. Lett. 1998, 80, 4450] which is exponentially decaying for large\ndistances and crosses over, at the corona diameter of the star, to an ultrasoft\nlogarithmic repulsion for small distances. Excellent agreement is found in a\nbroad range of star arm numbers."
    },
    {
        "anchor": "Polymer translocation in an environment of active rods: We consider the dynamics of a translocation process of a flexible linear\npolymer through a nanopore into an environment of active rods in the {\\it\ntrans} side. Using Langevin dynamics simulations we find that the rods\nfacilitate translocation to the {\\it trans} side even when there are initially\nmore monomers on the {\\it cis} than on the {\\it trans} side. Structural\nanalysis of the translocating polymer reveals that active rods induce a folded\nstructure to the {\\it trans}-side subchain in the case of successful\ntranslocation events. By keeping the initial number of monomers on the {\\it\ncis}-side subchain fixed, we map out a state diagram for successful events as a\nfunction of the rod number density for a variety of system parameters. This\nreveals competition between facilitation by the rods at low densities and\ncrowding that hinders translocation at higher densities.",
        "positive": "A fluctuating environment as a source of periodic modulation: We study the intermittent fluorescence of a single molecule, jumping from the\n\"light on\" to the \"light off\" state, as a Poisson process modulated by a\nfluctuating environment. We show that the quasi-periodic and\nquasi-deterministic environmental fluctuations make the distribution of the\ntimes of sojourn in the \"light off\" state depart from the exponential form, and\nthat their succession in time mirrors environmental dynamics. As an\nillustration, we discuss some recent experimental results, where the\nenvironmental fluctuations depend on enzymatic activity."
    },
    {
        "anchor": "Swelling of ionic microgel particles in the presence of excluded-volume\n  interactions: a density functional approach: In this work a new density functional theory framework is developed to\npredict the salt-concentration dependent swelling state of charged microgels\nand the local concentration of monovalent ions inside and outside the microgel.\nFor this purpose, elastic, solvent-induced and electrostatic contributions to\nthe microgel free energy are considered together with the free energy of the\nions. In addition to the electrostatic interaction, the model explicitly\nconsiders both the microgel-ion excluded-volume (steric) repulsion and the\nionic correlations, in such a way that the formalism is consistent with the\nHypernetted-Chain Closure approximation (HNC). We explore the role that the\nsolvent quality, chain elasticity, salt concentration and microgel bare charge\nplay on the swelling state, the effective charge and on the ionic density\nprofiles. Our results show that the microgel-ion steric exclusion foments the\nincrease of the particle size up to 10 %. The role that the steric effect plays\non the counterion distribution becomes more important when the microgel\napproaches the shrunken configuration, developing an accumulation peak at the\nmicrogel interface and a reduction in the inner core of the microgel that\ninduce a significant increase of the microgel effective charge. We further find\nthat deep inside the particle charge electroneutrality is achieved and a Donnan\npotential corrected by the steric exclusion is established.",
        "positive": "Conversion of $^{40}$K-$^{87}$Rb mixtures into stable molecules: We study the conversion of $^{40}$K and $^{87}$Rb atoms into stable molecules\nthrough the stimulated Raman adiabatic passage (STIRAP) in photoassociation\nassisted with Feshbach resonance. Starting with the mean-field Langrange\ndensity, we show that the atom-to-molecule conversion efficiency by STIRAP\naided by Feshbach resonance is much larger than that by bare Feshbach\nresonance. We also study the influence of the population imbalance on the\natom-to-molecule conversion."
    },
    {
        "anchor": "Specific heat in two-dimensional melting: We report the specific heat $c_N$ around the melting transition(s) of\nmicrometer-sized superparamagnetic particles confined in two dimensions,\ncalculated from fluctuations of positions and internal energy, and\ncorresponding Monte Carlo simulations. Since colloidal systems provide single\nparticle resolution, they offer the unique possibility to compare the\nexperimental temperatures of peak position of $c_N(T)$ and symmetry breaking,\nrespectively. While order parameter correlation functions confirm the\nKosterlitz-Thouless-Halperin-Nelson-Young melting scenario where translational\nand orientational order symmetries are broken at different temperatures with an\nintermediate so called hexatic phase, we observe a single peak of the specific\nheat within the hexatic phase, with excellent agreement between experiment and\nsimulation. Thus, the peak is not associated with broken symmetries but can be\nexplained with the total defect density, which correlates with the maximum\nincrease of isolated dislocations. The absence of a latent heat strongly\nsupports the continuous character of both transitions.",
        "positive": "Translocation of a Polymer through a Nanopore across a Viscosity\n  Gradient: The translocation of a polymer through a pore in a membrane separating fluids\nof different viscosities is studied via several computational approaches.\nStarting with the polymer halfway, we find that as a viscosity difference\nacross the pore is introduced, translocation will predominately occur towards\none side of the membrane. These results suggest an intrinsic pumping mechanism\nfor translocation across cell walls which could arise whenever the fluid across\nthe membrane is inhomogeneous. Somewhat surprisingly, the sign of the preferred\ndirection of translocation is found to be strongly dependent on the simulation\nalgorithm: for Langevin Dynamics (LD) simulations, a bias towards the low\nviscosity side is found while for Brownian Dynamics (BD), a bias towards the\nhigh viscosity is found. Examining the translocation dynamics in detail across\na wide range of viscosity gradients and developing a simple force model to\nestimate the magnitude of the bias, the LD results are demonstrated to be more\nphysically realistic. The LD results are also compared to those generated from\na simple, one dimensional random walk model of translocation to investigate the\nrole of the internal degrees of freedom of the polymer and the entropic\nbarrier. To conclude, the scaling of the results across different polymer\nlengths demonstrates the saturation of the preferential direction with polymer\nlength and the non-trivial location of the maximum in the exponent\ncorresponding to the scaling of the translocation time with polymer length."
    },
    {
        "anchor": "Minimal Model for Dynamic Bonding in Colloidal Transient Networks: We investigate a model for colloidal network formation using Brownian\nDynamics computer simulations. Hysteretic springs establish transient bonds\nbetween particles with repulsive core. If a bonded pair is separated by a\ncutoff distance, the spring vanishes and reappears only if the two particles\ncontact each other. We present results for the the bond lifetime distribution\nand investigate the properties of the van Hove dynamical two-body correlation\nfunction. The model displays crossover from fluid-like dynamics, via transient\nnetwork formation, to arrested quasi-static network behavior.",
        "positive": "The EXP pair-potential system. I. Fluid phase isotherms, isochores, and\n  quasiuniversality: The exponentially repulsive EXP pair potential defines a system of particles\nin terms of which simple liquids' quasiuniversality may be explained [A. K.\nBacher et al., Nat. Commun. 5, 5424 (2014); J. C. Dyre, J. Phys. Condens.\nMatter 28, 323001 (2016)]. This paper and its companion present a detailed\nsimulation study of the EXP system. Here we study how structure monitored via\nthe radial distribution function and dynamics monitored via the mean-square\ndisplacement as a function of time evolve along the system's isotherms and\nisochores. The focus is on the gas and liquid phases, which are distinguished\npragmatically by the absence or presence of a minimum in the radial\ndistribution function above its first maximum. An NVU-based proof of\nquasiuniversality is presented, and quasiuniversality is illustrated by showing\nthat the structure of the Lennard-Jones system at four selected state points is\nwell approximated by those of EXP pair-potential systems with the same reduced\ndiffusion constant. The companion paper studies the EXP system's isomorphs,\nfocusing also on the gas and liquid phases."
    },
    {
        "anchor": "Correlated dynamics of weakly charged silica spheres at an air-water\n  interface: Optical microscopy and multi-particle tracking are used to investigate the\nspatially correlated motion of weakly charged silica spheres at an air-water\ninterface for different area fraction $n$ occupied by the particles. When the\narea fraction is very small, e.g. $n=0.03$, the correlation function along the\nline joining the centers of particles $D_{rr}$ decays with inter-particle\ndistance $R$ as $1/R^{0.86\\pm0.02}$, and the function perpendicular to this\nline $D_{\\theta\\theta}$ decays with $R$ as $1/R^{1.45\\pm0.03}$, which differs\nfrom the results of [Phys. Rev. Lett. 97, 176001 (2006)] with low surface\nviscosity (where $D_{rr}\\propto 1/R$, $D_{\\theta\\theta}\\propto 1/R^2$). We\nargue that the differences arise from the Coulomb interaction between\nparticles. The Coulomb interaction enhances the correlated motion of particles.\nExperimental results show that with the increase of $n$, the decay rate of\n$D_{rr}$ and $D_{\\theta\\theta}$ with $R$ decreases and the cross-correlation\nenhances for the Coulomb interaction increases. The Coulomb interaction between\ncolloidal particles should serve as an effective surface viscoelastical role in\nour system. With the scaled separation $\\frac R {d}(\\frac {\\eta_{w}d}\n{\\eta_{es,2p}})^{3/2}$, the correlated motions for various values of $n$ and\ndifferent particles can be scaled onto a single master curve, where $d$ is\nparticles' diameter, $\\eta_{w}$ is the viscosity of the water, and\n$\\eta_{es,2p}$ is the effective surface viscosity whose measurements agree well\nwith that of one-particle surface viscosity $\\eta_{es,1p}$. The effective\nsurface viscosity $\\eta_{es,2p}$ as a function of the area fraction $n$ for\ndifferent silica spheres is presented.",
        "positive": "Specific Adhesion of Peptides on Semiconductor Surfaces in Experiment\n  and Simulation: We report on self-assembly, clustering, and conformational phases of peptides\non inorganic semiconductor surfaces. The peptide-covered surface fraction can\ndiffer by a factor of 25, depending mainly on surface and peptide polarity. Low\nadhesion induces large and soft clusters, which also have high contact angles\nto the surface. Direct surface adhesion of a peptide molecule competes with\nforming molecular aggregates which offer an overall reduced surface contact.\nSimulating a simple hybrid model yields a pseudophase diagram with a rich,\ntemperature and solvent-quality dependent variety of subphases which are\nspecific to the hydrophobicity and polarity of the considered substrates."
    },
    {
        "anchor": "Barchan dune corridors: field characterization and investigation of\n  control parameters: The structure of the barchan field located between Tarfaya and Laayoune\n(Atlantic Sahara, Morocco) is quantitatively investigated and compared to that\nin La Pampa de la Joya (Arequipa, Peru). On the basis of field measurements, we\nshow how the volume, the velocity and the output sand flux of a dune can be\ncomputed from the value of its body and horn widths. The dune size distribution\nis obtained from the analysis of aerial photographs. It shows that these fields\nare in a statistically homogeneous state along the wind direction and present a\n`corridor' structure in the transverse direction, in which the dunes have a\nrather well selected size. Investigating the possible external parameters\ncontrolling these corridors, we demonstrate that none among topography,\ngranulometry, wind and sand flux is relevant. We finally discuss the dynamical\nprocesses at work in these fields (collisions and wind fluctuations), and\ninvestigate the way they could regulate the size of the dunes. Furthermore we\nshow that the overall sand flux transported by a dune field is smaller than the\nmaximum transport that could be reached in the absence of dunes, i.e. in\nsaltation over the solid ground.",
        "positive": "Flux ratios for effects of permanent charges on ionic flows with three\n  ion species: Case study (II): In this paper, we study effects of permanent charges on ion flows through\nmembrane channels via a quasi-one-dimensional classical Poisson-Nernst-Planck\nsystem. This system includes three ion species, two cations with different\nvalences and one anion, and permanent charges with a simple structure, zeros at\nthe two end regions and a constant over the middle region. For small permanent\ncharges, our main goal is to analyze the effects of permanent charges on ionic\nflows, interacting with the boundary conditions and channel structure.\nContinuing from a previous work, we investigate the problem for a new case\ntoward a more comprehensive understanding about effects of permanent charges on\nionic fluxes."
    },
    {
        "anchor": "How colloidal suspensions that age are rejuvenated by strain application: We present here a microscopic study of the effect of shear on a dense purely\nrepulsive colloidal suspension. We use Multispeckle Diffusing Wave Spectroscopy\nto monitor the transient motions of colloidal particles after being submitted\nto an oscillatory strain. This technique proves efficient to record the time\nevolution of the relaxation times distribution. After a high oscillatory shear,\nwe show that this distribution displays a full aging behavior. Oppositely, when\na moderate shear is applied the distribution is modified in a non trivial way.\nWhereas high shear is able to erase all the sample history and rejuvenate it, a\nmoderate shear helps it to age. We call this phenomena overaging. We\ndemonstrate that overaging can be understood if the complete shape of the\nrelaxation time distribution is taken into account. We finally report how the\nSoft Glassy Rheology model accounts for this effect.",
        "positive": "Room temperature water Leidenfrost droplets: We experimentally investigate the Leidenfrost effect at pressures ranging\nfrom 1 to 0.05 atmospheric pressure. As a direct consequence of the\nClausius-Clapeyron phase diagram of water, the droplet temperature can be at\nambient temperature in a non-sophisticated lab environment. Furthermore, the\nlifetime of the Leidenfrost droplet is significantly increased in this low\npressure environment. The temperature and pressure dependance of the\nevaporation rate are successfully tested against a recently proposed model.\nThese results may pave a way to reach efficient Leidenfrost micro-fluidic and\nmilli-fluidic applications."
    },
    {
        "anchor": "A sheet on deformable sphere: \"wrinklogami\" patterns suppress\n  curvature-induced delamination: The adhesion of a stiff film onto a curved substrate often generates elastic\nstresses in the film that eventually give rise to its delamination. Here we\npredict that delamination of very thin films can be dramatically suppressed\nthrough tiny, smooth deformations of the substrate, dubbed here \"wrinklogami\",\nthat barely affect the macroscale topography. This \"pro-lamination\" effect\nreflects a surprising capability of smooth wrinkles to suppress compression in\nelastic films even when spherical or other doubly-curved topography is imposed,\nin a similar fashion to origami folds that enable construction of curved\nstructures from an unstretchable paper. We show that the emergence of a\nwrinklogami pattern signals a nontrivial isometry of the sheet to its planar,\nundeformed state, in the doubly asymptotic limit of small thickness and weak\ntensile load exerted by the adhesive substrate. We explain how such an\n\"asymptotic isometry\" concept broadens the standard usage of isometries for\ndescribing the response of elastic sheets to geomertric constraints and\nmechanical loads.",
        "positive": "Entropic Tightening of Vibrated Chains: We investigate experimentally the distribution of configurations of a ring\nwith an elementary topological constraint, a ``figure-8'' twist. Using vibrated\ngranular chains, which permit controlled preparation and direct observation of\nsuch a constraint, we show that configurations where one of the loops is tight\nand the second is large are strongly preferred. This agrees with recent\npredictions for equilibrium properties of topologically-constrained polymers.\nHowever, the dynamics of the tightening process weakly violate detailed\nbalance, a signature of the nonequilibrium nature of this system."
    },
    {
        "anchor": "Contribution of transverse modes to the dynamics of density fluctuations: The transverse and longitudinal current correlation functions are evaluated\nin liquid and amorphous sodium by computer simulation. The study of the\ncorresponding spectra as a function of the wavevector $k$ allows the evaluation\nof a dispersion curve for their peak position. The results are compared with\nrecent experimental findings [PNAS 107, 21985 (2010)], obtained by a new\nanalysis of $S(k,{\\omega})$ measured by inelastic X-ray scattering in liquid\nand polycrystalline sodium. A substantial agreement between experimental and\ncomputer simulation results is found. The analysis of the line widths supports\nthe Vibration-Transit theory picture of the dynamics in liquids.",
        "positive": "Dipolar Capillary Interactions between Tilted Ellipsoidal Particles\n  Adsorbed at Fluid-Fluid Interfaces: Capillary interactions have emerged as a tool for the directed assembly of\nparticles adsorbed at fluid-fluid interfaces, and play a role in controlling\nthe mechanical properties of emulsions and foams. In this paper, following\nDavies et al. [Advanced Materials, 26, 6715 (2014)] investigation into the\nassembly of ellipsoidal particles at interfaces interacting via dipolar\ncapillary interactions, we numerically investigate the interaction between\ntilted ellipsoidal particles adsorbed at a fluid-fluid interface as their\naspect ratio, tilt angle, bond angle, and separation vary. High-resolution\nSurface Evolver simulations of ellipsoidal particle pairs in contact reveal an\nenergy barrier between a metastable tip-tip configuration and a stable\nside-side configuration. The side-side configuration is the global energy\nminimum for all parameters we investigated. Lattice Boltzmann simulations of\nclusters of up to 12 ellipsoidal particles show novel highly symmetric\nflower-like and ring-like arrangements."
    },
    {
        "anchor": "Nonlinear alternating current responses of dipolar fluids: The frequency-dependent nonlinear dielectric increment of dipolar fluids in\nnonpolar fluids is often measured by using a stationary relaxation method in\nwhich two electric fields are used: The static direct current (DC) field of\nhigh strength causing the dielectric nonlinearity, and the probing alternating\ncurrent (AC) field of low strength and high frequency. When a nonlinear\ncomposite is subjected to a sinusoidal electric field, the electric response in\nthe composite will, in general, consist of AC fields at frequencies of\nhigher-order harmonics. Based on the Froehlich model, we present a theory to\ninvestigate nonlinear AC responses of dipolar fluids containing both\npolarizable monomers and dimers. In the case of monomers only, our theory\nreproduces the known results. We obtain the fundamental, second-, and\nthird-order harmonics of the Froehlich field by performing a perturbation\nexpansion. The even-order harmonics are induced by the coupling between the AC\nand DC fields although the system under consideration has a cubic nonlinearity\nonly. The harmonics of the Froehlich field can be affected by the field\nfrequency, temperature, dispersion strength and the characteristic frequency of\nthe dipolar fluid, as well as the dielectric constant of the nonpolar fluid.\nThe results are found to be in agreement with recent experimental observations.",
        "positive": "Nonspherical armoured bubble vibration: In this paper, we study the dynamics of cylindrical armoured bubbles excited\nby mechanical vibrations. A step by step transition from cylindrical to\nspherical shape is reported as the intensity of the vibration is increased,\nleading to a reduction of the bubble surface and a dissemination of the excess\nparticles. We demonstrate through energy balance that nonspherical armoured\nbubbles constitute a metastable state. The vibration instills the activation\nenergy necessary for the bubble to return to its least energetic stable state:\na spherical armoured bubble. At this point, particle desorption can only be\nachieved through higher amplitude of excitation required to overcome capillary\nretention forces. Nonspherical armoured bubbles open perspectives for tailored\nlocalized particle dissemination with limited excitation power."
    },
    {
        "anchor": "Sequence design-based control of DNA droplets formed from phase\n  separation of DNA nanostructures: DNA has the potential to realize a controllable liquid-liquid phase\nseparation (LLPS) system, because the design of its base sequences results in\nprogrammable interactions. Here, we have developed a novel DNA-based LLPS\nsystem which enables us to create 'DNA droplets' and to control their dynamic\nbehaviour by designing sequences of the DNA nanostructure. We were able to\nchange the phase separation temperature required for the formation of DNA\ndroplets by designing the sequences. In addition, the fusion, fission, and\nformation of Janus-shaped droplets were controlled by sequence design and\nenzymatic reactions. Furthermore, modifications of proteins with\nsequence-designed DNAs allowed for their capture into specific droplets.\nOverall, our results provide a new platform for designing the phase behaviour\nof macromolecular structures, and paves the way for new applications of\nsequence-designed DNA in the creation of cell-mimicries, synthetic membraneless\norganelles, and artificial molecular systems.",
        "positive": "Nematic liquid crystals in contact with geometrically and chemically\n  patterned substrates: A Monte Carlo Study: Nematic liquid crystals confined to geometrically as well as chemically\npatterned substrate on one end and a flat substrate with strong anchoring on\nthe other is studied using non-Boltzmann Monte Carlo methods. We observe\nsignificant deviations from the continuum-based predictions of the phase\ndiagram which was studied as a function of tilt angle at the top substrate and\nthickness of the cell. Onset of biaxiality at larger tilt angles at the top\nsubstrate is observed. A phase shift introduced between the geometrical and\nchemical pattern has significant effect on the director structures in the\nsystem."
    },
    {
        "anchor": "Probing roto-translational diffusion of small anisotropic colloidal\n  particles with a bright-field microscope: Soft and biological materials are often composed of elementary constituents\nexhibiting an incessant roto-translational motion at the microscopic scale.\nTracking this motion with a bright-field microscope becomes increasingly\nchallenging when the particle size becomes smaller than the microscope\nresolution, a case which is frequently encountered. Here we demonstrate\nSquared-Gradient Differential Dynamic Microscopy (SG-DDM) as a tool to\nsuccessfully use bright-field microscopy to extract the roto-translational\ndynamics of small anisotropic colloidal particles, whose rotational motion\ncannot be tracked accurately in direct space. We provide analytical\njustification and experimental demonstration of the method by successful\napplication to an aqueous suspension of peanut-shaped particles.",
        "positive": "Apparent line tension induced by surface-active impurities: Line tension in wetting processes is of high scientific and technological\nrelevance, but its understanding remains vague, mainly because of its difficult\ndetermination. A widely used method to extract the line tension relies on the\nvariation of a droplet's contact angle with the droplet's size. This approach\nyields the apparent line tension, which factors in numerous contributions to\nthe finite-size dependence, thus masking the actual line tension in terms of\nthe excess free energy of the three-phase contact line. Based on our recent\ncomputer simulation study, we investigate how small amounts of nonionic\nsurfactants, such as surface-active impurities, contribute to the apparent line\ntension in aqueous droplets. When depositing polydisperse droplets, their\ndifferent surface-area-to-volume ratios can result in different final bulk\nconcentrations of surfactants, different excess adsorptions to interfaces, and,\nconsequently, different contact angles. We show that already trace amounts of\nlonger-chained surfactants are enough to cause a measurable effect on the\napparent line tension. Our analysis quantifies to what extent \"background\"\nimpurities, inevitably present in all experimental settings, limit the\nresolution of line-tension measurements, which is crucial for avoiding data\nmisinterpretation."
    },
    {
        "anchor": "A constrained random-force model for weakly bending semiflexible\n  polymers: The random-force (Larkin) model of a directed elastic string subject to\nquenched random forces in the transverse directions has been a paradigm in the\nstatistical physics of disordered systems. In this brief note, we investigate a\nmodified version of the above model where the total transverse force along the\npolymer contour and the related total torque, in each realization of disorder,\nvanish. We discuss the merits of adding these constraints and show that they\nleave the qualitative behavior in the strong stretching regime unchanged, but\nthey reduce the effects of the random force by significant numerical\nprefactors. We also show that a transverse random force effectively makes the\nfilament softer to compression by inducing undulations. We calculate the\nrelated linear compression coefficient in both the usual and the constrained\nrandom force model.",
        "positive": "Optomechanical elastomeric engine: Nematic elastomers contract along their director when heated or illuminated\n(in the case of photoelastomers). We present a conceptual design for an\nelastomer-based engine to extract mechanical work from heat or light. The\nmaterial parameters and the geometry of such an engine are explored, and it is\nshown that its efficiency can go up to 20%."
    },
    {
        "anchor": "Rheology primer for nanoparticle scientists: Mechanical properties are intrinsically related to the structures and\ndynamics of systems. The main tools to investigate mechanical properties are\nrheology and microrheology. Those techniques can focus on the macroscopic and\nmicroscopic mechanical properties of any kind of colloidal system and/or\nnanostructures. Several kinds of experiments can be conducted to study the\nmechanical properties of colloidal systems; however, their interpretation might\nnot be always straightforward. Here, our purpose is to provide a simple guide\nfor beginners on most common rheological experiments.",
        "positive": "The bouncing dynamics of inertial self-propelled particles reveals\n  directional asymmetry: This study aims to examine experimental conditions in which active particles\nare forced by their surroundings to move forward and backward in a continuous\noscillatory manner. The experimental design is based on using a vibrating\nself-propelled toy-robot called hexbug, which is placed inside a narrow channel\nclosed on one end by a rigid moving wall. Using the end-wall velocity as a\ncontrolling factor, the main forward mode of the hexbug movement can be turned\nto mostly rearward mode. We investigate the bouncing hexbug motion on both\nexperimental and theoretical grounds. The Brownian model of active particles\nwith inertia is employed in the theoretical framework. The model itself uses a\npulsed Langevin equation in order to simulate abrupt changes in velocity that\nmimic hexbug propulsion in the moments when its legs make contact with the base\nplate. Significant directional asymmetry is caused by the legs bending\nbackward. We demonstrate that the simulation successfully reproduces the\nexperimental characteristics of hexbug motion after regressing the spatial and\ntemporal statistical characteristics, especially when directional asymmetry is\nunder consideration."
    },
    {
        "anchor": "Complex dynamics of long, flexible fibers in shear: The macroscopic properties of polymeric fluids are inherited from the\nmaterial properties of the fibers embedded in the solvent. The behavior of such\npassive fibers in flow has been of interest in a wide range of systems,\nincluding cellular mechanics, nutrient aquisition by diatom chains in the\nocean, and industrial applications such as paper manufacturing. The rotational\ndynamics and shape evolution of fibers in shear depends upon the slenderness of\nthe fiber and the non-dimensional \"elasto-viscous\" number that measures the\nratio of the fluid's viscous forces to the fiber's elastic forces. For a small\nelasto-viscous number, the nearly-rigid fiber rotates in the shear, but when\nthe elasto-viscous number reaches a threshhold, buckling occurs. For even\nlarger elasto-viscous numbers, there is a transition to a \"snaking behavior\"\nwhere the fiber remains aligned with the shear axis, but its ends curl in, in\nopposite directions. These experimentally-observed behaviors have recently been\ncharacterized computationally using slender-body theory and immersed boundary\ncomputations. However, classical experiments with nylon fibers and recent\nexperiments with actin filaments have demonstrated that for even larger\nelasto-viscous numbers, multiple buckling sites and coiling can occur. Using a\nregularized Stokeslet framework coupled with a kernel independent fast\nmultipole method, we present simulations that capture these complex fiber\ndynamics.",
        "positive": "Frequency dependence of specific heat in supercooled liquid water and\n  emergence of correlated dynamics: Molecular origin of the well-known specific heat anomaly in supercooled\nliquid water is investigated here by using extensive computer simulations and\ntheoretical analyses. A rather sharp increase in the values of isobaric\nspecific heat with lowering temperature and the weak temperature dependence of\nisochoric specific heat in the same range are reproduced in simulations. We\ncalculated the spatiotemporal correlation among temperature fluctuations and\nexamined the frequency dependent specific heat. The latter shows a rapid growth\nin the low frequency regime as temperature is cooled below 270 K. In order to\nunderstand the microscopic basis of this increase, we have performed a shell\nwise decomposition of contributions of distant molecules to the temperature\nfluctuations in a central molecule. This decomposition reveals the emergence,\nat low temperatures, of temporally slow, spatially long ranged large\ntemperature fluctuations. The temperature fluctuation time correlation function\n(TFCF) can be fitted to a William-Watts stretched exponential form with the\nstretching parameter close to 0.6 at low temperatures, indicating highly\nnon-exponential relaxation. Temperature dependence of the relaxation time of\nthe correlation function can be fitted to Vogel-Fulcher-Tamermann expression\nwhich provides a quantitative measure of the fragility of the liquid.\nInterestingly, we find that the rapid growth in the relaxation time of TFCF\nwith lowering temperature undergoes a sharp crossover from a markedly fragile\nstate to a weakly fragile state around 220 K."
    },
    {
        "anchor": "Molecular theory of electrostatic collapse of dipolar polymer gels: We develop a new quantitative molecular theory of liquid-phase dipolar\npolymer gels. We model monomer units of the polymer network as a couple of\ncharged sites separated by a fluctuating distance. For the first time, within\nthe random phase approximation, we have obtained an analytical expression for\nthe electrostatic free energy of the dipolar gel. Depending on the coupling\nparameter of dipole-dipole interactions and the ratio of the dipole length to\nthe subchain Kuhn length, we describe the gel collapse induced by electrostatic\ninteractions in the good solvent regime as a first-order phase transition. This\ntransition can be realized at reasonable physical parameters of the system\n(temperature, solvent dielectric constant, and dipole moment of monomer units).\nThe obtained results could be potentially used in modern applications of\nstimuli-responsive polymer gels and microgels, such as drug delivery,\nnanoreactors, molecular uptake, coatings, superabsorbents, etc.",
        "positive": "Self-assembly and rheology of dipolar colloids in simple shear - studied\n  by multi-particle collision dynamics: Magnetic nanoparticles in a colloidal solution self-assemble in various\naligned structures, which has a profound influence on the flow behavior.\nHowever, the precise role of the microstructure in the development of the\nrheological response has not been reliably quantified. We investigate the\nself-assembly of dipolar colloids in simple shear using hybrid molecular\ndynamics and multi-particle collision dynamics simulations with explicit\ncoarse-grained hydrodynamics; conduct simulated rheometric studies and apply\nmicromechanical models to produce master curves, showing evidence of the\nuniversality of the structural behavior governed by the competition of the\nbonding (dipolar) and erosive (thermal and/or hydrodynamic) stresses. The\nsimulations display viscosity changes across several orders of magnitude in\nfair quantitative agreement with various literature sources, substantiating the\nuniversality of the approach, which seems to apply generally across vastly\ndifferent length scales and a broad range of physical systems."
    },
    {
        "anchor": "Time-Dependent Variational Analysis of Josephson Oscillations in a\n  Two-component Bose-Einstein Condensate: The dynamics of Josephson-like oscillations between two coupled Bose-Einstein\ncondensates is studied using the time-dependent variational method. We suppose\nthat the quantum state of the condensates is a gaussian wave-packet which can\ntranslate and perform breathing shape oscillations. Under this hypotheses we\nstudy the influence of these degrees of freedom on the tunneling dynamics by\ncomparing the full-model with one where these degrees of freedom are ``frozen''\nat its equilibrium values. The result of our calculation shows that when the\ntraps are not displaced the two models agree, whereas when they are, the models\ndiffer considerably, the former being now closer to its linear approximation.",
        "positive": "Thermodynamically Stable Blue Phases: We show theoretically that flexoelectricity stabilizes blue phases in chiral\nliquid crystals. Induced internal polarization reduces the elastic energy cost\nof splay and bend deformations surrounding singular lines in the director\nfield. The energy of regions of double twist is unchanged. This in turn reduces\nthe free energy of the blue phase with respect to that of the chiral nematic\nphase, leading to stability over a wider temperature range. The theory explains\nthe discovery of large temperature range blue phases in highly flexoelectric\n\"bimesogenic\" and \"bent-core\" materials, and predicts how this range may be\nincreased further."
    },
    {
        "anchor": "A colloid approach to self-assembling antibodies: Concentrated solutions of monoclonal antibodies have attracted considerable\nattention due to their importance in pharmaceutical formulations, yet their\ntendency to aggregate and the resulting high solution viscosity has posed\nconsiderable problems. It remains a very difficult task to understand and\npredict the phase behavior and stability of such solutions. Here we present a\nsystematic study of the concentration dependence of the structural and dynamic\nproperties of monoclonal antibodies using a combination of different scattering\nmethods and microrheological experiments. To interpret these data, we use a\ncolloid-inspired approach based on a simple patchy model, which explicitly\ntakes into account the anisotropic shape and the charge distribution of the\nmolecules. Combining theory, simulations and experiments, we are able to\ndisentangle self-assembly and intermolecular interactions and to quantitatively\ndescribe the concentration dependence of structural and dynamic quantities such\nas the osmotic compressibility, the collective diffusion coefficient and the\nzero shear viscosity over the entire range of investigated concentrations. This\nsimple patchy model not only allows us to consistently describe the\nthermodynamic and dynamic behavior of mAb solutions, but also provides a robust\nestimate of the attraction between their binding sites. It will thus be an\nideal starting point for future work on antibody formulations, as it provides a\nquantitative assessment of the effects of additional excipients or chemical\nmodifications on antibody interactions, and a prediction of their effect on\nsolution viscosity.",
        "positive": "Development of configurational forces during the injection of an elastic\n  rod: When an inextensible elastic rod is 'injected' through a sliding sleeve\nagainst a fixed constraint, configurational forces are developed, deeply\ninfluencing the mechanical response. This effect, which is a consequence of the\nchange in length of the portion of the rod included between the sliding sleeve\nand the fixed constraint, is theoretically demonstrated (via integration of the\nelastica) and experimentally validated on a proof-of-concept structure\n(displaying an interesting force reversal in the load/deflection diagram), to\nprovide conclusive evidence to mechanical phenomena relevant in several\ntechnologies, including guide wire for artery catheterization, or wellbore\ninsertion of a steel pipe."
    },
    {
        "anchor": "Active Colloidal Molecules: Like ordinary molecules are composed of atoms, colloidal molecules consist of\nseveral species of colloidal particles tightly bound together. If one of these\ncomponents is self-propelled or swimming, novel \"active colloidal molecules\"\nemerge. Active colloidal molecules exist on various levels such as\n\"homonuclear\", \"heteronuclear\" and \"polymeric\" and possess a dynamical function\nmoving as propellers, spinners or rotors. Self-assembly of such active\ncomplexes has been studied a lot recently and this perspective article\nsummarizes recent progress and gives an outlook to future developments in the\nrapidly expanding field of active colloidal molecules.",
        "positive": "Towards a scale-bridging description of ferrogels and magnetic\n  elastomers: Ferrogels and magnetic elastomers differentiate themselves from other\nmaterials by their unique capability of reversibly changing shape and\nmechanical properties under the influence of an external magnetic field. A\ncrucial issue in the study of these outstanding materials is the interaction\nbetween the mesoscopic magnetic particles and the polymer matrix in which they\nare embedded. Here we analyze interactions between two such particles connected\nby a polymer chain, a situation representative for particle-crosslinked\nmagnetic gels. To make a first step towards a scale-bridging description of the\nmaterials, effective potentials for mesoscopic configurational changes are\nspecified using microscopic input obtained from simulations. Furthermore, the\nimpact of the presence of magnetic interactions on the probability\ndistributions and thermodynamic quantities of the system is considered. The\nresulting mesoscopic model potentials can be used to economically model the\nsystem on the particle length scales. This first coarse-graining step is\nimportant to realize simplified but realistic scale-bridging models for these\npromising materials."
    },
    {
        "anchor": "Elongated particles discharged with a conveyor belt in a two-dimensional\n  silo: The flow of elliptical particles out of a 2-dimensional silo when extracted\nwith a conveyor belt is analyzed experimentally. The conveyor belt - placed\ndirectly below the silo outlet - reduces the flow rate, increases the size of\nthe stagnant zone, and it has a very strong influence on the relative velocity\nfluctuations as they strongly increase everywhere in the silo with decreasing\nbelt speed. In other words, instead of slower but smooth flow, flow reduction\nby belt leads to intermittent flow. Interestingly, we show that this\nintermittency correlates with a strong reduction of the orientational order of\nthe particles at the orifice region. Moreover, we observe that the average\norientation of the grains passing through the outlet is modified when they are\nextracted with the belt, a feature that becomes more evident for large\norifices.",
        "positive": "Non-additive electronic polarizabilities of ionic liquids: Charge\n  delocalization effects: Electronic charge delocalization on the molecular backbones of ionic\nliquid-forming ions substantially impacts their molecular polarizabilities.\nDensity functional theory calculations of polarizabilities and volumes of many\ncations and anions are reported and applied to yield refractive indices of 1216\nionic liquids. A novel expression for the precise estimation of the molecular\nvolumes of the ionic liquids from simulation data is also introduced, adding\nquadratic corrections to the usual sum of atomic volumes. Our significant\nfindings include i) that the usual assumption of uniform, additive atomic\npolarizabilities is challenged when highly mobile electrons in conjugated\nsystems are present, and ii) that cations with conjugated large carbon chains\ncan be used together with anions for the design of ionic liquids with very high\nrefractive indices. A novel relation for the polarizability volume is reported\ntogether with a refractive index map made up of the studied ionic liquids"
    },
    {
        "anchor": "Scale-dependent rigidity of polymer-ornamented membranes: We study the fluctuation spectrum of fluid membranes carrying grafted\npolymers. Contrary to usual descriptions, we find that the modifications\ninduced by the polymers cannot be reduced to the renormalization of the\nmembrane bending rigidity. Instead we show that the ornamented membrane\nexhibits a scale-dependent elastic modulus that we evaluate. In ornamented\nlamellar stacks, we further show that this leads to a modification of the\nCaille parameter characterizing the power-law singularities of the Bragg peaks.",
        "positive": "Nucleation and growth by diffusion under Ostwald-Freundlich boundary\n  condition: The critical radius of a nucleus grown by diffusion in a solution is studied\nthermodynamically as well as kinetically. The thermodynamic growth equation\ncalled Zeldovich equation of classical nucleation theory (CNT) and the kinetic\ndiffusional growth equation combined with the Ostwald-Freundlich boundary\ncondition lead to the same critical radius. However, it should be pointed out\nthat the diffusional equation may lead to a kinetic critical radius that is\ndifferent from the thermodynamic critical radius, thus indicating the\npossibility of kinetically controlling the critical radius of a nucleus."
    },
    {
        "anchor": "Dominant negative Poynting effect for soft tissues: We identify three distinct shearing modes for simple shear deformations of\ntransversely isotropic soft tissue which allow for both positive and negative\nPoynting effects (that is, they require compressive and tensile lateral normal\nstresses, respectively, in order to maintain simple shear). The positive\nPoynting effect is that usually found for isotropic rubber. Here,\nspecialisation of the general results to three strain-energy functions which\nare quadratic in the anisotropic invariants, linear in the isotropic strain\ninvariants and consistent with the linear theory suggests that there are two\nPoynting effects which can accompany the shearing of soft tissue: a dominant\nnegative effect in one mode of shear and a relatively small positive effect in\nthe other two modes. We propose that the relative inextensibility of the fibres\nrelative to the matrix is the primary mechanism behind this large negative\nPoynting effect.",
        "positive": "Shallow granular flows down flat frictional channels: steady flows and\n  longitudinal vortices: Granular flows down inclined channels with smooth boundaries are common in\nnature and in the industry. Nevertheless, the common setup of flat boundaries\nhas comparatively been much less investigated than the bumpy boundaries one,\nwhich is used by most experimental and numerical studies to avoid sliding\neffects. Using DEM numerical simulations with side walls we recover\nquantitatively experimental results. At larger angles we predict a rich\nbehavior, including granular convection and inverted density profiles\nsuggesting a Rayleigh-B\\'enard type of instability. In many aspects flows on a\nflat base can be seen as flows over an effective bumpy base made of the basal\nrolling layer, giving Bagnold-type profiles in the overburden over that layer.\nWe have tested a simple viscoplastic rheological model (Nature 2006, vol 441,\npp727-730) in average form. The transition between the unidirectional and the\nconvective flows is then clearly apparent as a discontinuity in the\nconstitutive relation."
    },
    {
        "anchor": "Observation of photon-assisted tunneling in optical lattices: We have observed tunneling suppression and photon-assisted tunneling of\nBose-Einstein condensates in an optical lattice subjected to a constant force\nplus a sinusoidal shaking. For a sufficiently large constant force, the ground\nenergy levels of the lattice are shifted out of resonance and tunneling is\nsuppressed; when the shaking is switched on, the levels are coupled by\nlow-frequency photons and tunneling resumes. Our results agree well with\ntheoretical predictions and demonstrate the usefulness of optical lattices for\nstudying solid-state phenomena.",
        "positive": "Modelling receding contact lines on superhydrophobic surfaces: We use mesoscale simulations to study the depinning of a receding contact\nline on a superhydrophobic surface patterned by a regular array of posts. In\norder that the simulations are feasible, we introduce a novel geometry where a\ncolumn of liquid dewets a capillary bounded by a superhydrophobic plane which\nfaces a smooth hydrophilic wall of variable contact angle. We present results\nfor the dependence of the depinning angle on the shape and spacing of the\nposts, and discuss the form of the meniscus at depinning. We find, in agreement\nwith [17], that the local post concentration is a primary factor in controlling\nthe depinning angle, and show that the numerical results agree well with recent\nexperiments. We also present two examples of metastable pinned configurations\nwhere the posts are partially wet."
    },
    {
        "anchor": "The Foam Analogy in Charged Colloidal Crystals: We model charged colloidal suspensions using an analogy with foams. We study\nthe solid--solid phase transitions of these systems as a function of particle\nvolume-fraction and ionic strength. The screened Coulomb interaction is\nreplaced by an interaction between walls of the Voronoi cells around each\nparticle. We fit the surface charge to reproduce the phase diagram for the\ncharged suspension studied by Sirota, et al. [Phys. Rev. Lett. 62, 1524\n(1989)]. With this fit parameter we are able to calculate the elastic moduli of\nthe system and find good agreement with the available data.",
        "positive": "Application of a two-length scale field theory to the solvation of\n  charged molecules: I. Hydrophobic effect revisited: On a basis of a two-length scale description of hydrophobic interactions we\ndevelop a continuous self-consistent theory of solute-water interactions which\nallows to determine a hydrophobic layer of a solute molecules of any geometry\nwith explicit account of solvent structure described by its correlation\nfunction. We compute the mean solvent density profile n(r) surrounding the\nspherical solute molecule as well as its solvation free energy. We compare the\ntwo-length scale theory to the numerical data of Monte-Carlo simulations found\nin the literature and discuss the possibility of a self-consistent adjustment\nof the free parameters of the theory. In the frameworks of the discussed\napproach we compute also the solvation free energies of alkane molecules and\nthe free energy of interaction of two spheres separated by some distance. We\ndescribe the general setting of a self-consistent account of electrostatic\ninteractions in the frameworks of the model where the water is considered not\nas a continuous media, but as a gas of dipoles. We analyze the limiting cases\nwhere the proposed theory coincides with the electrostatics of a continuous\nmedia."
    },
    {
        "anchor": "Internal dynamics and activated processes in Soft-Glassy materials: Plastic rearrangements play a crucial role in the characterization of\nsoft-glassy materials, such as emulsions and foams. Based on numerical\nsimulations of soft-glassy systems, we study the dynamics of plastic\nrearrangements at the hydrodynamic scales where thermal fluctuations can be\nneglected. Plastic rearrangements require an energy input, which can be either\nprovided by external sources, or made available through time evolution in the\ncoarsening dynamics, in which the total interfacial area decreases as a\nconsequence of the slow evolution of the dispersed phase from smaller to large\ndroplets/bubbles. We first demonstrate that our hydrodynamic model can\nquantitatively reproduce such coarsening dynamics. Then, considering\nperiodically oscillating strains, we characterize the number of plastic\nrearrangements as a function of the external energy-supply, and show that they\ncan be regarded as activated processes induced by a suitable \"noise\" effect.\nHere we use the word noise in a broad sense, referring to the internal\nnon-equilibrium dynamics triggered by spatial random heterogeneities and\ncoarsening. Finally, by exploring the interplay between the internal\ncharacteristic time-scale of the coarsening dynamics and the external\ntime-scale associated with the imposed oscillating strain, we show that the\nsystem exhibits the phenomenon of stochastic resonance, thereby providing\nfurther credit to the mechanical activation scenario.",
        "positive": "Stability of bicontinuous cubic phases in ternary amphiphilic systems\n  with spontaneous curvature: We study the phase behavior of ternary amphiphilic systems in the framework\nof a curvature model with non-vanishing spontaneous curvature. The amphiphilic\nmonolayers can arrange in different ways to form micellar, hexagonal, lamellar\nand various bicontinuous cubic phases. For the latter case we consider both\nsingle structures (one monolayer) and double structures (two monolayers). Their\ninterfaces are modeled by the triply periodic surfaces of constant mean\ncurvature of the families G, D, P, C(P), I-WP and F-RD. The stability of the\ndifferent bicontinuous cubic phases can be explained by the way in which their\nuniversal geometrical properties conspire with the concentration constraints.\nFor vanishing saddle-splay modulus $\\bar \\kappa$, almost every phase considered\nhas some region of stability in the Gibbs triangle. Although bicontinuous cubic\nphases are suppressed by sufficiently negative values of the saddle-splay\nmodulus $\\bar \\kappa$, we find that they can exist for considerably lower\nvalues than obtained previously. The most stable bicontinuous cubic phases with\ndecreasing $\\bar \\kappa < 0$ are the single and double gyroid structures since\nthey combine favorable topological properties with extreme volume fractions."
    },
    {
        "anchor": "Pattern formation by non-dissipative arrest of turbulent cascades: Fully developed turbulence is a universal and scale-invariant chaotic state\ncharacterized by an energy cascade from large to small scales where the cascade\nis eventually arrested by dissipation. In this Letter, we show how to harness\nthese seemingly structureless turbulent cascades to generate patterns.\nConceptually, pattern or structure formation entails a process of wavelength\nselection: patterns typically arise from the linear instability of a\nhomogeneous state. By contrast, the mechanism we propose here is fully\nnon-linear and triggered by a non-dissipative arrest of turbulent cascades.\nInstead of being dissipated, energy piles up at intermediate scales. Using a\ncombination of theory and large-scale simulations, we show that the tunable\nwavelength of these cascade-induced patterns is set by a non-dissipative\ntransport coefficient called odd or gyro viscosity. This non-dissipative\nviscosity is ubiquitous in chiral systems ranging from plasmas, bio-active\nmedia and quantum fluids. Beyond chiral fluids, cascade-induced pattern\nformation could occur in natural systems including oceanic and atmospheric\nflows, planetary and stellar plasma such as the solar wind, as well as in\nindustrial processes such as the pulverization of objects into debris or in\nchemistry and biology where the coagulation of droplets can be interrupted at a\ntunable scale.",
        "positive": "Collapse Transition of Two-Dimensional Flexible and Semiflexible\n  Polymers: The nature of the globule-coil transition of surface-confined polymers has\nbeen an issue of debate. Here this 2D collapse transition is studied through a\npartially directed lattice model. In the general case of polymers with positive\nbending stiffness ($\\Delta>0$), the collapse transition is {\\em first-order};\nit becomes {\\em second-order} only in the limiting case of zero bending\nstiffness ($\\Delta\\equiv 0$). These analytical results are confirmed by Monte\nCarlo simulations. We also suggest some possible future experiments."
    },
    {
        "anchor": "Weak violation of universality for Polyelectrolyte Chains: Variational\n  Theory and Simulations: A variational approach is considered to calculate the free energy and the\nconformational properties of a polyelectrolyte chain in $d$ dimensions. We\nconsider in detail the case of pure Coulombic interactions between the\nmonomers, when screening is not present, in order to compute the end-to-end\ndistance and the asymptotic properties of the chain as a function of the\npolymer chain length $N$. We find $R \\simeq N^{\\nu}(\\log N)^{\\gamma}$ where\n$\\nu = \\frac{3}{\\lambda+2}$ and $\\lambda$ is the exponent which characterize\nthe long-range interaction $U \\propto 1/r^{\\lambda}$. The exponent $\\gamma$ is\nshown to be non-universal, depending on the strength of the Coulomb\ninteraction. We check our findings, by a direct numerical minimization of the\nvariational energy for chains of increasing size $2^4<N<2^{15}$. The\nelectrostatic blob picture, expected for small enough values of the interaction\nstrength, is quantitatively described by the variational approach. We perform a\nMonte Carlo simulation for chains of length $2^4<N<2^{10}$. The non universal\nbehavior of the exponent $ \\gamma$ previously derived within the variational\nmethod, is also confirmed by the simulation results. Non-universal behavior is\nfound for a polyelectrolyte chain in $d=3$ dimension. Particular attention is\ndevoted to the homopolymer chain problem, when short range contact interactions\nare present.",
        "positive": "Testing mean-field theory for jamming of non-spherical particles:\n  Contact number, gap distribution, and vibrational density of states: We perform numerical simulations of the jamming transition of non-spherical\nparticles in two dimensions. In particular, we systematically investigate how\nthe physical quantities at the jamming transition point behave when the shapes\nof the particle deviate slightly from the perfect disks. For efficient\nnumerical simulation, we first derive an analytical expression of the gap\nfunction, using the perturbation theory around the reference disks. Starting\nfrom disks, we observe the effects of the deformation of the shapes of\nparticles by the $n$-th order term of the Fourier series $\\sin(n\\theta)$. We\nshow that the several physical quantities, such as the number of contacts, gap\ndistribution, and characteristic frequencies of the vibrational density of\nstates, show the power-law behaviors with respect to the linear deviation from\nthe reference disks. The power-law behaviors do not depend on $n$ and are fully\nconsistent with the mean-field theory of the jamming of non-spherical\nparticles. This result suggests that the mean-field theory holds very generally\nfor nearly spherical particles whose shape can be expressed by the Fourier\nseries."
    },
    {
        "anchor": "Effect of anharmonicities in the critical number of trapped condensed\n  atoms with attractive two-body interaction: We determine the quantitative effect, in the maximum number of particles and\nother static observables, due to small anharmonic terms added to the confining\npotential of an atomic condensed system with negative two-body interaction. As\nan example of how a cubic or quartic anharmonic term can affect the maximum\nnumber of particles, we consider the trap parameters and the results given by\nRoberts et al. [Phys. Rev. Lett. 86, 4211 (2001)]. However, this study can be\neasily transferred to other trap geometries to estimate anharmonic effects.",
        "positive": "Non-Newtonian rheology in twist-bend nematic liquid crystals: In this work we present a simple qualitative model to describe shear\nrheological behavior of the twist-bend nematic liquid crystals. We find that at\nrelatively low shear rate the effective viscosity decreases with the shear rate\nmanifesting so-called shear-thinning phenomenon. At intermediate shear rate the\nstress is almost independent of the shear rate (a sort of plateau), and at\nlarge shear rate Newtonian rheology takes place. Within our theory we estimate\nthe critical values of the shear rate in terms of coarse grained shear\nviscosity coefficients of the effective smectics equivalent to the twist-bend\nphase at large scales. The results of our work are in the agreement with recent\nexperimental studies."
    },
    {
        "anchor": "Kink motion in the Kramers problem for a chain molecule: We consider the generalization of the Kramers escape over a barrier problem\nto the case of a long chain molecule. It involves the motion of chain molecule\nof N segments across a region where the free energy per segment is higher, so\nthat it has to cross a barrier. We use the Rouse model and find that the free\nenergy of activation has a square root dependence on the temperature leading to\na non-Arrhenius form for the rate. We also show that there is a special time\ndependent solution of the model, which corresponds to a kink in the chain,\nconfined to the region of the barrier. The polymer goes from one side to the\nother by the motion of the kink in the reverse direction. If there is no free\nenergy difference between the two sides of the barrier, then the kink moves by\ndiffusion and the time of crossing t_{cross}~ N^2/T^{3/2}. If there is a free\nenergy difference, then the kink moves with a non-zero velocity from the lower\nfree energy side to the otherleading to t_{cross} ~ N/sqrt{T}.",
        "positive": "Breakdown of Scaling and Friction Weakening in the Critical Granular\n  Flow: The way granular materials response to an applied shear stress is of the\nutmost relevance to both human activities and natural environment. One of the\ntheir most intriguing and less understood behavior, is the stick-instability,\nwhose most dramatic manifestation are earthquakes, ultimately governed by the\ndynamics of rocks and debris jammed within the fault gauge. Many of the\nfeatures of earthquakes, i.e. intermittency, broad times and energy scale\ninvolved, are mimicked by a very simple experimental set-up, where small beads\nof glass under load are slowly sheared by an elastic medium. Analyzing data\nfrom long lasting experiments, we identify a critical dynamical regime, that\ncan be related to known theoretical models used for \"crackling-noise\"\nphenomena. In particular, we focus on the average shape of the slip velocity,\nobserving a \"breakdown of scaling\": while small slips show a self-similar\nshape, large does not, in a way that suggests the presence of subtle inertial\neffects within the granular system. In order to characterise the crossover\nbetween the two regimes, we investigate the frictional response of the system,\nwhich we trat as a stochastic quantity. Computing different averages, we\nevidence a weakening effect, whose Stribeck threshold velocity can be related\nto the aforementioned breaking of scaling."
    },
    {
        "anchor": "Wrinkling of a spherical lipid interface induced by actomyosin cortex: Actomyosin actively generates contractile forces that provide the plasma\nmembrane with the deformation stresses essential to carry out biological\nprocesses. Although the contractile property of purified actomyosin has been\nextensively studied, to understand the physical contribution of the actiomyosin\ncontractile force on a deformable membrane is still a challenging problem and\nof great interest in the field of biophysics. Here, we reconstituted a model\nsystem with a cell-sized deformable interface that exhibits anomalous curvature\ndependent wrinkling caused by actomyosin cortex underneath the spherical closed\ninterface. Through the shape analysis of the wrinkling deformation, we found\nthat the dominant contributor on the wrinkled shape changes from bending\nelasticity to stretching elasticity of the reconstituted cortex by increasing\nthe droplet curvature radius of the order of the cell-size, i.e., tens of\nmicrometer. The observed curvature dependence was explained by the theoretical\ndescription of the cortex elasticity and contractility. Our present results\nprovide a fundamental insight on the deformation of a curved membrane induced\nby the actomyosin cortex.",
        "positive": "A framework for crossover of scaling law as a self-similar solution :\n  dynamical impact of viscoelastic board: In this paper, a new framework for crossover of scaling law is proposed: a\ncrossover of scaling law can be described by a self-similar solution. A\ncrossover emerges as a result of the interference from similarity parameters of\nthe higher class of the self-similarity. This framework was verified for the\ndynamical impact of solid sphere onto a viscoelastic board. All the physical\nfactors including the size of spheres and the impact of velocity are\nsuccessfully summarized using primal dimensionless numbers which construct a\nself-similar solution of the second kind, which represents the balance between\ndynamical elements involved in the problem. The self-similar solution gives two\ndifferent scaling laws by the perturbation method describing the crossover.\nThese theoretical predictions are compared with experimental results to show\ngood agreement. It was suggested that a hierarchical structure of similarity\nplays a fundamental role on crossover, which offers a fundamental insight to\nself-similarity in general."
    },
    {
        "anchor": "Mechanical annealing of model glasses: Effects of strain amplitude and\n  temperature: Molecular dynamics simulations are performed to examine the dynamic response\nof amorphous solids to oscillatory shear at finite temperatures. The data were\ncollected from a poorly annealed binary glass, which was deformed periodically\nin the elastic regime during several hundred shear cycles. We found that the\ncharacteristic time required to reach a steady state with a minimum potential\nenergy is longer at higher temperatures and larger strain amplitudes. With\ndecreasing strain amplitude, the asymptotic value of the potential energy\nincreases but it remains lower than in quiescent samples. The transient decay\nof the potential energy correlates well with a gradual decrease in the volume\noccupied by atoms with large nonaffine displacements. By contrast, the maximum\namplitude of shear stress oscillations is attained relatively quickly when a\nlarge part of the system starts to deform reversibly.",
        "positive": "Vapor Condensed and Supercooled Glassy Nanoclusters: We use molecular simulation to study the structural and dynamic properties of\nglassy nanoclusters formed both through the direct condensation of the vapor\nbelow the glass transition temperature, without the presence of a substrate,\nand \\textit{via} the slow supercooling of unsupported liquid nanodroplets. An\nanalysis of local structure using Voronoi polyhedra shows that the energetic\nstability of the clusters is characterized by a large, increasing fraction of\nbicapped square antiprism motifs. We also show that nanoclusters with similar\ninherent structure energies are structurally similar, independent of their\nhistory, which suggests the supercooled clusters access the same low energy\nregions of the potential energy landscape as the vapor condensed clusters\ndespite their different methods of formation. By measuring the intermediate\nscattering function at different radii from the cluster center, we find that\nthe relaxation dynamics of the clusters are inhomogeneous, with the core\nbecoming glassy above the glass transition temperature while the surface\nremains mobile at low temperatures. This helps the clusters sample the highly\nstable, low energy structures on the potential energy surface. Our work\nsuggests the nanocluster systems are structurally more stable than the\nultra-stable glassy thin films, formed through vapor deposition onto a cold\nsubstrate, but the nanoclusters do not exhibit the superheating effects\ncharacteristic of the ultra-stable glass states."
    },
    {
        "anchor": "Phase diagram of two-dimensional hard ellipses: We report the phase diagram of two-dimensional hard ellipses as obtained from\nreplica exchange Monte Carlo simulations. The replica exchange is implemented\nby expanding the isobaric ensemble in pressure. The phase diagram shows four\nregions: isotropic, nematic, plastic, and solid (letting aside the hexatic\nphase at the isotropic-plastic two-step transition [PRL 107, 155704 (2011)]).\nAt low anisotropies, the isotropic fluid turns into a plastic phase which in\nturn yields a solid for increasing pressure (area fraction). Intermediate\nanisotropies lead to a single first order transition (isotropic-solid).\nFinally, large anisotropies yield an isotropic-nematic transition at low\npressures and a high-pressure nematic-solid transition. We obtain continuous\nisotropic-nematic transitions. For the transitions involving quasi-long-range\npositional ordering, i. e. isotropic-plastic, isotropic-solid, and\nnematic-solid, we observe bimodal probability density functions. This supports\nfirst order transition scenarios.",
        "positive": "Effects of nanoparticles and surfactant on droplets in shear flow: We present three-dimensional numerical simulations, employing the\nwell-established lattice Boltzmann method, and investigate similarities and\ndifferences between surfactants and nanoparticles as additives at a fluid-fluid\ninterface. We report on their respective effects on the surface tension of such\nan interface. Next, we subject a fluid droplet to shear and explore the\ndeformation properties of the droplet, its inclination angle relative to the\nshear flow, the dynamics of the particles at the interface, and the possibility\nof breakup. Particles are seen not to affect the surface tension of the\ninterface, although they do change the overall interfacial free energy. The\nparticles do not remain homogeneously distributed over the interface, but form\nclusters in preferred regions that are stable for as long as the shear is\napplied. However, although the overall structure remains stable, individual\nnanoparticles roam the droplet interface, with a frequency of revolution that\nis highest in the middle of the droplet interface, normal to the shear flow,\nand increases with capillary number. We recover Taylor's law for small\ndeformation of droplets when surfactant or particles are added to the droplet\ninterface. The effect of surfactant is captured in the capillary number, but\nthe inertia of adsorbed massive particles increases deformation at higher\ncapillary number and eventually leads to easier breakup of the droplet."
    },
    {
        "anchor": "Nonlinear dynamics of a shear banding interface: We study numerically the nonlinear dynamics of a shear banding interface in\ntwo dimensional planar shear flow, within the non-local Johnson Segalman model.\nConsistent with a recent linear stability analysis, we find that an initially\nflat interface is unstable with respect to small undulations for sufficiently\nsmall ratio of the interfacial width $\\ell$ to cell length $L_x$. The\ninstability saturates in finite amplitude interfacial fluctuations. For\ndecreasing $\\ell/L_x$ these undergo a non equilibrium transition from simple\ntravelling interfacial waves with constant average wall stress, to periodically\nrippling waves with a periodic stress response. When multiple shear bands are\npresent we find erratic interfacial dynamics and a stress response suggesting\nlow dimensional chaos.",
        "positive": "Active Matter Commensuration and Frustration Effects on Periodic\n  Substrates: We show that self-driven particles coupled to a periodic obstacle array\nexhibit novel active matter commensuration effects that are absent in the\nBrownian limit. As the obstacle size is varied for sufficiently large activity,\na series of commensuration effects appear in which the motility induced phase\nseparation produces commensurate crystalline states, while for other obstacle\nsizes we find frustrated or amorphous states. The commensuration effects are\nassociated with peaks in the amount of six-fold ordering and the maximum\ncluster size. When a drift force is added to the system, the mobility contains\npeaks and dips similar to those found in transport studies for commensuration\neffects in superconducting vortices and colloidal particles."
    },
    {
        "anchor": "Surface instability of sheared soft tissues: When a block made of an elastomer is subjected to large shear, its surface\nremains flat. When a block of biological soft tissue is subjected to large\nshear, it is likely that its surface in the plane of shear will buckle\n(apparition of wrinkles). One factor that distinguishes soft tissues from\nrubber-like solids is the presence -- sometimes visible to the naked eye -- of\noriented collagen fibre bundles, which are stiffer than the elastin matrix into\nwhich they are embedded but are nonetheless flexible and extensible. Here we\nshow that the simplest model of isotropic nonlinear elasticity, namely the\nincompressible neo-Hookean model, suffers surface instability in shear only at\ntremendous amounts of shear, i.e., above 3.09, which corresponds to a 72\ndegrees angle of shear. Next we incorporate a family of parallel fibres in the\nmodel and show that the resulting solid can be either reinforced or strongly\nweakened with respect to surface instability, depending on the angle between\nthe fibres and the direction of shear, and depending on the ratio E/mu between\nthe stiffness of the fibres and that of the matrix. For this ratio we use\nvalues compatible with experimental data on soft tissues. Broadly speaking, we\nfind that the surface becomes rapidly unstable when the shear takes place\n\"against\" the fibres, and that as E/mu increases, so does the sector of angles\nwhere early instability is expected to occur.",
        "positive": "Computing optimal interfacial structure of modulated phases: We propose a general framework of computing interfacial structures between\ntwo modulated phases. Specifically we propose to use a computational box\nconsisting of two half spaces, each occupied by a modulated phase with given\nposition and orientation. The boundary conditions and basis functions are\nchosen to be commensurate with the bulk structures. It is observed that the\nordered nature of modulated structures stabilizes the interface, which enables\nus to obtain optimal interfacial structures by searching local minima of the\nfree energy landscape. The framework is applied to the Landau-Brazovskii model\nto investigate interfaces between modulated phases with different relative\npositions and orientations. Several types of novel complex interfacial\nstructures are obtained from the calculations."
    },
    {
        "anchor": "Alternative derivation of the Feigel effect and call for its\n  experimental verification: A recent theory by Feigel [Phys. Rev. Lett. {\\bf 92}, 020404 (2004)] predicts\nthe finite transfer of momentum from the quantum vacuum to a fluid placed in\nstrong perpendicular electric and magnetic fields. The momentum transfer arises\nbecause of the optically anisotropic magnetoelectric response induced in the\nfluid by the fields. After summarising Feigel's original assumptions and\nderivation (corrected of trivial mistakes), we rederive the same result by a\nsimpler route, validating Feigel's semi-classical approach. We then derive the\nstress exerted by the vacuum on the fluid which, if the Feigel hypothesis is\ncorrect, should induce a Poiseuille flow in a tube with maximum speed $\\approx\n100\\mu$m/s (2000 times larger than Feigel's original prediction). An experiment\nis suggested to test this prediction for an organometallic fluid in a tube\npassing through the bore of a high strength magnet. The predicted flow can be\nmeasured directly by tracking microscopy or indirectly by measuring the flow\nrate ($\\approx 1$ml/min) corresponding to the Poiseuille flow. A second\nexperiment is also proposed whereby a `vacuum radiometer' is used to test a\nrecent prediction that the net force on a magnetoelectric slab in the vacuum\nshould be zero.",
        "positive": "Probing interface localization-delocalization transitions by colloids: Interface localization-delocalization transitions (ILDT) occur in two-phase\nfluids confined in a slit with competing preferences of the walls for the two\nfluid phases. At low temperatures the interface between the two phases is\nlocalized at one of the walls. Upon increasing temperature it unbinds. Although\nintensively studied theoretically and computationally, such transitions have\nnot yet been observed experimentally due to severe challenges in resolving fine\ndetails of the fluid structure. Here, using mean field theory and Monte Carlo\nsimulations of the Ising model, we propose to detect these ILDT by using\ncolloids. We show that the finite-size and fluctuation induced force acting on\na colloid confined in such a system experiences a vivid change if, upon\nlowering the temperature, the interface localizes at one of the walls. This\nchange can serve as a more easily accessible experimental indicator of the\ntransition."
    },
    {
        "anchor": "Mechanics of Interfacial Composite Materials: Recent experiments and simulations have demonstrated that particle-covered\ninterfaces can exist in stable non-spherical shapes as a result of the steric\njamming of the interfacially trapped particles, which confers the interface\nwith solid-like properties. We provide an experimental and theoretical\ncharacterization of the mechanical properties of these armored objects, with\nattention given to the two-dimensional granular state of the interface. Small\ninhomogeneous stresses produce a plastic response while homogeneous stresses\nproduce a weak elastic response. Shear-driven particle-scale rearrangements\nexplain the basic threshold needed to obtain the near-perfect plastic\ndeformation that is observed. Furthermore, the inhomogeneous stress state of\nthe interface is exhibited experimentally by using surfactants to destabilize\nthe particles on the surface. Since the interfacially trapped particles retain\ntheir individual characteristics, armored interfaces can be recognized as a\nkind of composite material with distinct chemical, structural and mechanical\nproperties.",
        "positive": "Disordered, stretched, and semiflexible biopolymers in two dimensions: We study the effects of intrinsic sequence-dependent curvature for a two\ndimensional semiflexible biopolymer with short-range correlation in intrinsic\ncurvatures. We show exactly that when not subjected to any external force, such\na system is equivalent to a system with a well-defined intrinsic curvature and\na proper renormalized persistence length. We find the exact expression for the\ndistribution function of the equivalent system. However, we show that such an\nequivalent system does not always exist for the polymer subjected to an\nexternal force. We find that under an external force, the effect of\nsequence-disorder depends upon the averaging order, the degree of disorder, and\nthe experimental conditions, such as the boundary conditions. Furthermore, a\nshort to moderate length biopolymer may be much softer or has a smaller\napparent persistent length than what would be expected from the \"equivalent\nsystem\". Moreover, under a strong stretching force and for a long biopolymer,\nthe sequence-disorder is immaterial for elasticity. Finally, the effect of\nsequence-disorder may depend upon the quantity considered."
    },
    {
        "anchor": "Investigating isomorphs with the topological cluster classification: Isomorphs are lines in the density-temperature plane of certain\n\"strongly-correlating\" or \"Roskilde simple\" liquids where two-point structure\nand dynamics have been shown to be close to identical up to a scale\ntransformation. Here we consider such a liquid, a Lennard-Jones glassformer,\nand investigate the behavior along isomorphs of higher-order structural and\ndynamical correlations. We then consider an inverse power law reference system\nmapped to the Lennard-Jones system [Pedersen et al., Phys. Rev. Lett. 105,\n157801 (2010)]. Using the topological cluster classification to identify\nhigher-order structures, in both systems we find bicapped square anti-prisms,\nwhich are known to be a locally favored structure in the Lennard-Jones\nglassformer. The population of these locally favored structures is up to 80%\nhigher in the Lennard-Jones system than the equivalent inverse power law\nsystem. The structural relaxation time of the two systems, on the other hand,\nis almost identical, and the four-point dynamical susceptibility is marginally\nhigher in the inverse power law system. Upon cooling the lifetime of the\nlocally favored structures in the Lennard-Jones system are up to 40% higher\nrelative to the reference system.",
        "positive": "Edge pinning and transformation of defect lines induced by faceted\n  colloidal rings in nematic liquid crystals: Nematic colloids exhibit a large diversity of topological defects and\nstructures induced by colloidal particles in the orientationally ordered liquid\ncrystal host fluids. These defects and field configurations define elastic\ninteractions and medium-mediated self-assembly, as well as serve as model\nsystems in exploiting the richness of interactions between topologies and\ngeometries of colloidal surfaces, nematic fields, and topological singularities\ninduced by particles in the nematic bulk and at nematic-colloidal interfaces.\nHere we demonstrate formation of quarter-strength surface-pinned disclinations,\nas well as a large variety of director field configurations with splitting and\nreconnections of singular defect lines, prompted by colloidal particles with\nsharp edges and size large enough to define strong boundary conditions. Using\nexamples of faceted ring-shaped particles of genus g = 1, we explore\ntransformation of defect lines as they migrate between locations in the bulk of\nthe nematic host to edge-pinned locations at the surfaces of particles and vice\nversa, showing that this behavior is compliant with topological constraints\ndefined by mathematical theorems. We discuss how transformation of bulk and\nsurface defect lines induced by faceted colloids can enrich the diversity of\nelasticity-mediated colloidal interactions and how these findings may impinge\non prospects of their controlled reconfigurable self-assembly in nematic hosts."
    },
    {
        "anchor": "Collision of Polymers in a Vacuum: In a number of experimental situations, single polymer molecules can be\nsuspended in a vacuum. Here collisions between such molecules are considered.\nThe limit of high collision velocity is investigated numerically for a variety\nof conditions. The distribution of contact times, scattering angles, and final\nvelocities are analyzed. In this limit, self avoiding chains are found to\nbecome highly stretched as they collide with each other, and have a\ndistribution of scattering times that depends on the scattering angle. The\nvelocity of the molecules after the collisions is similar to predictions of a\nmodel assuming thermal equilibration of molecules during the collision. The\nmost important difference is a significant subset of molecules that\ninelastically scatter but do not substantially change direction.",
        "positive": "Critical Diameter for Continuous Evaporation is between 3 nm and 4 nm\n  for Hydrophilic Nanopores: Evaporation studies of water using classical molecular dynamics simulations\nare largely limited due to their high computational expense. This study\naddresses that issue by developing coarse-grained molecular dynamics models\nbased on Morse potential. Models are optimized based on multi-temperature and\nat room temperature using machine learning techniques like genetic algorithm,\nNelder-Mead algorithm, and Strength Pareto Evolutionary Algorithm. The\nmulti-temperature based model named as Morse-D is found to be more accurate\nthan single temperature model in representing the water properties at higher\ntemperatures. Using this Morse-D water model, evaporation from hydrophilic\nnanopores with pore diameter varying from 2 nm to 5 nm is studied. Our results\nshow that the critical diameter to initiate continuous evaporation at nanopores\nlies between 3 nm and 4 nm. A maximum heat flux of 21.3 kW/cm2 is observed for\na pore diameter of 4.5 nm and a maximum mass flow rate of 16.2 ng/s for a pore\ndiameter of 5 nm. The observed heat flux is an order of magnitude times larger\nthan the currently reported values from experiments in the literature for\nwater, which indicates that we need to focus on nanoscale evaporation to\nenhance the critical heat flux."
    },
    {
        "anchor": "Supramolecular Thermo Aero-able Gelators (STAGs) for synthesis of\n  hydrogels: Supramolecular Thermo Aero-able Gelators (STAGs): tartaric acid, urea, and\nguanidine with amide and imine moieties as supramolecular synthons are\nintroduced to cross-link and aerate ('aero-able') polyacrylate networks for\nsynthesis of hydrogels. They are bi-functional hence present a greener\nalternative to the existing cross-linkers and gelators.",
        "positive": "Phase diagram and structure of colloid-polymer mixtures confined between\n  walls: The influence of confinement, due to flat parallel structureless walls, on\nphase separation in colloid-polymer mixtures, is investigated by means of\ngrand-canonical Monte Carlo simulations. Ultra-thin films, with thicknesses\nbetween $D=3-10$ colloid diameters, are studied. The Asakura-Oosawa model [J.\nChem. Phys. 22, 1255 (1954)] is used to describe the particle interactions. To\nsimulate efficiently, a ``cluster move'' [J. Chem. Phys. 121, 3253 (2004)] is\nused in conjunction with successive umbrella sampling [J. Chem. Phys. 120,\n10925 (2004)]. These techniques, when combined with finite size scaling, enable\nan accurate determination of the unmixing binodal. Our results show that the\ncritical behavior of the confined mixture is described by ``effective''\ncritical exponents, which gradually develop from values near those of the\ntwo-dimensional Ising model, to those of the three-dimensional Ising model, as\n$D$ increases. The scaling predictions of Fisher and Nakanishi [J. Chem. Phys.\n75, 5875 (1981)] for the shift of the critical point are compatible with our\nsimulation results. Surprisingly, however, the colloid packing fraction at\ncriticality approaches its bulk ($D \\to \\infty$) value non-monotonically, as\n$D$ is increased. Far from the critical point, our results are compatible with\nthe simple Kelvin equation, implying a shift of order 1/D in the coexistence\ncolloid chemical potential. We also present density profiles and pair\ndistribution functions for a number of state points on the binodal, and the\ninfluence of the colloid-wall interaction is studied."
    },
    {
        "anchor": "Direct observation of crystal nucleation and growth in a\n  quasi-two-dimensional nonvibrating granular system: We study a quasi-two-dimensional macroscopic system of magnetic spherical\nparticles settled on a shallow concave dish under a temporally oscillating\nmagnetic field. The system reaches a stationary state where the energy losses\nfrom collisions and friction with the concave dish surface are compensated by\nthe continuous energy input coming from the oscillating magnetic field. Random\nparticle motions show some similarities with the motions of atoms and molecules\nin a glass or a crystal-forming fluid. Because of the curvature of the surface,\nparticles experience an additional force toward the center of the concave dish.\nWhen decreasing the magnetic field, the effective temperature is decreased and\ndiffusive particle motion slows. For slow cooling rates we observe\ncrystallization, where the particles organize into a hexagonal lattice. We\nstudy the birth of the crystalline nucleus and the subsequent growth of the\ncrystal. Our observations support non-classical theories of crystal formation.\nInitially a dense amorphous aggregate of particles forms, and then in a second\nstage this aggregate rearranges internally to form the crystalline nucleus. As\nthe aggregate grows, the crystal grows in its interior. After a certain size,\nall the aggregated particles are part of the crystal and after that, crystal\ngrowth follows the classical theory for crystal growth.",
        "positive": "Mode-Coupling Theory of Colloids with Short-range Attractions: Within the framework of the mode-coupling theory of super-cooled liquids, we\ninvestigate new phenomena in colloidal systems on approach to their glass\ntransitions. When the inter-particle potential contains an attractive part,\nbesides the usual repulsive hard core, two intersecting liquid-glass transition\nlines appear, one of which extends to low densities, while the other one, at\nhigh densities, shows a re-entrant behaviour. In the glassy region a new type\nof transition appears between two different types of glasses. The complex\nphenomenology can be described in terms of higher order glass transition\nsingularities. The various glass phases are characterised by means of their\nviscoelastic properties. The glass driven by attractions has been associated to\nparticle gels, and the other glass is the well known repulsive colloidal glass.\nThese correspondences, in associations with the new predictions of glassy\nbehaviour mean that such phenomena may be expected in colloidal systems with,\nfor example, strong depletion or other short-ranged attractive potentials."
    },
    {
        "anchor": "The Sound of Sonoluminescence: We consider an air bubble in water under conditions of single bubble\nsonoluminescence (SBSL) and evaluate the emitted sound field nonperturbatively\nfor subsonic gas-liquid interface motion. Sound emission being the dominant\ndamping mechanism, we also implement the nonperturbative sound damping in the\nRayleigh-Plesset equation for the interface motion. We evaluate numerically the\nsound pulse emitted during bubble collapse and compare the nonperturbative and\nperturbative results, showing that the usual perturbative description leads to\nan overestimate of the maximal surface velocity and maximal sound pressure. The\nradius vs. time relation for a full SBSL cycle remains deceptively unaffected.",
        "positive": "Equation of state in the generalized density scaling regime studied from\n  ambient to ultra-high pressure conditions: In this paper, based on the effective intermolecular potential with well\nseparated density and configuration contributions and the definition of the\nisothermal bulk modulus, we derive two similar equations of state dedicated to\ndescribe volumetric data of supercooled liquids studied in the extremely wide\npressure range related to the extremely wide density range. Both the equations\ncomply with the generalized density scaling law of molecular dynamics versus\n$h(\\rho ) / T$ at different densities $\\rho $ and temperatures $T$, where the\nscaling exponent can be in general only a density function $\\gamma(\\rho ) =\n\\it{d} \\rm{ln} \\it{h / d} \\rm{ln}\\rho $ as recently argued by the theory of\nisomorphs. We successfully verify these equations of state by using data\nobtained from molecular dynamics simulations of the Kob-Andersen binary\nLennard-Jones liquid. As a very important result, we find that the\none-parameter density function $h(\\rho )$ analytically formulated in the case\nof this prototypical model of supercooled liquid, which implies the\none-parameter density function $\\gamma(\\rho )$, is able to scale the structural\nrelaxation times with the value of this function parameter determined by\nfitting the volumetric simulation data to the equations of state. We also show\nthat these equations of state properly describe the pressure dependences of the\nisothermal bulk modulus and the configurational isothermal bulk modulus in the\nextremely wide pressure range investigated by the computer simulations.\nMoreover, we discuss the possible forms of the density functions $h(\\rho )$ and\n$\\gamma(\\rho )$ for real glass formers, which are suggested to be different\nfrom those valid for the model of supercooled liquid based on the Lennard-Jones\nintermolecular potential."
    },
    {
        "anchor": "Ferrofluidic aqueous two-phase system with ultralow interfacial tension,\n  instabilities and pattern formation: Ferrofluids are strongly magnetic fluids consisting of magnetic nanoparticles\ndispersed in a carrier fluid. Besides their technological applications, they\nhave a tendency to form beautiful and intriguing patterns when subjected to\nexternal static and dynamic magnetic fields. Most of the patterns occur in\nsystems consisting of two fluids: one ferrofluidic and one non-magnetic (oil,\nair, etc.), wherein the fluid-fluid interface deforms as a response to magnetic\nfields. Usually, the fluids are completely immiscible and so the interfacial\nenergy in this systems is very large. Here we show that it is possible to\ndesign a fully aqueous ferrofluid system by using phase separation of\nincompatible polymers. This continuous aqueous system allows an ultralow\ninterfacial tension (down to 1 $\\mu$N/m) and nearly vanishing pinning at three\nphase contact lines. We demonstrate the normal-field instability with the\nsystem and focus on the miniaturization of the pattern length from the typical\n$\\sim$10 mm size down to $\\sim$200 $\\mu$m. The normal-field instability is\ncharacterized in glass capillaries of thickness comparable to the pattern\nlength. This system paves way towards interesting physics such as the\ninteraction between magnetic instabilities and thermal capillary waves and\noffers a way to evaluate extremely small interfacial tensions.",
        "positive": "Oligomodal mechanical metamaterials: Mechanical metamaterials are artifical composites that exhibit a wide range\nof advanced functionalities such as negative Poisson's ratio, shape-shifting,\ntopological protection, multistability, and enhanced energy dissipation. To\ndate, most metamaterials have a single property, e.g. a single shape change, or\nare pluripotent, \\emph{i.e.} they can have many different responses, but\nrequire complex actuation protocols. Here, we introduce a novel class of\noligomodal metamaterials that encode a few distinct properties that can be\nselectively controlled under uniaxial compression. In particular, we realise a\nmetamaterial that has a negative (positive) Poisson's ratio for low (high)\ncompression rate. The ability of our oligomodal metamaterials to host multiple\nmechanical responses within a single structure makes them an early example of\nmulti-functional matter and paves the way towards robust and adaptable devices."
    },
    {
        "anchor": "Multicyclic modelling of softening in biological tissue: In this paper we derive a model to describe the important inelastic features\nassociated with the cyclic softening, often referred to as stress-softening, of\nsoft biological tissue. The model developed here includes the notion of\nmultiple stress-strain cycles with increasing values of the maximum strain. The\nmodel draws upon the similarities between the cyclic softening associated with\ncarbon-filled rubber vulcanizates and soft biological tissue. We give\nnon-linear transversely isotropic models for the elastic response, stress\nrelaxation, residual strain and creep of residual strain. These ideas are then\ncombined with a transversely isotropic version of the Arruda-Boyce eight-chain\nmodel to develop a constitutive relation that is capable of accurately\nrepresenting the multicyclic softening of soft biological tissue. To establish\nthe validity of the model we have compared it with experimental data from three\ncyclic uniaxial test samples, one taken from the \\textit{Manduca sexta}\n(tobacco hornworm) caterpillar and the other two samples taken from the human\naorta, one in the longitudinal and the other in the circumferential direction.\nThe model was found to fit these experimental data extremely well. {Keywords:}\nMullins effect, stress relaxation, creep of residual strain, biological tissue,\ntransverse isotropy. {MSC codes:} 74B20, 74D10, 74L15, 92C10",
        "positive": "Screening of Coulomb interactions in liquid dielectrics: The interaction of charges in dielectric materials is screened by the\ndielectric constant of the bulk dielectric. In dielectric theories, screening\nis assigned to the surface charge appearing from preferential orientations of\ndipoles along the local field in the interface. For liquid dielectrics, such\ninterfacial orientations are affected by the interfacial structure\ncharacterized by a separate interfacial dielectric susceptibility. We argue\nthat dielectric properties of polar liquids should be characterized by two\ndistinct susceptibilities responsible for local response (solvation) and\nlong-range response (dielectric screening). We develop a microscopic model of\nscreening showing that the standard bulk dielectric constant is responsible for\nscreening at large distances. The potential of mean force between ions in polar\nliquids becomes oscillatory at short distances. Oscillations arise from the\ncoupling of the collective longitudinal excitations of the dipoles in the bulk\nwith the interfacial structure of the liquid around the solutes."
    },
    {
        "anchor": "Negative stiffness and modulated states in active nematics: We examine the dynamics of a compressible active nematic liquid crystal on a\nfrictional substrate. When frictional damping dominates over viscous\ndissipation, we eliminate flow in favor of active stresses to obtain a minimal\ndynamical model for the nematic order parameter, with elastic constants\nrenormalized by activity. The renormalized elastic constants can become\nnegative at large activity, leading to the selection of spatially inhomogeneous\npatterns via a mechanism analogous to that responsible for modulated phases\narising at an equilibrium Lifshitz point. Tuning activity and the degree of\nnematic order in the passive system, we obtain a linear stability phase diagram\nthat exhibits a nonequilibrium tricritical point where ordered, modulated and\ndisordered phases meet. Numerical solution of the nonlinear equations yields a\nsuccession of spatial structures of increasing complexity with increasing\nactivity, including kink walls and active turbulence, as observed in\nexperiments on microtubule bundles confined at an oil-water interface. Our work\nprovides a minimal model for an overdamped active nematic that reproduces all\nthe nonequilibrium structures seen in simulations of the full active nematic\nhydrodynamics and provides a framework for understanding some of the mechanisms\nfor selection of the nonequilibrium patterns in the language of equilibrium\ncritical phenomena.",
        "positive": "Strain localization in a shear transformation zone model for amorphous\n  solids: We model a sheared disordered solid using the theory of Shear Transformation\nZones (STZs). In this mean-field continuum model the density of zones is\ngoverned by an effective temperature that approaches a steady state value as\nenergy is dissipated. We compare the STZ model to simulations by Shi, et\nal.(Phys. Rev. Lett. 98 185505 2007), finding that the model generates\nsolutions that fit the data,exhibit strain localization, and capture important\nfeatures of the localization process. We show that perturbations to the\neffective temperature grow due to an instability in the transient dynamics, but\nunstable systems do not always develop shear bands. Nonlinear energy\ndissipation processes interact with perturbation growth to determine whether a\nmaterial exhibits strain localization. By estimating the effects of these\ninteractions, we derive a criterion that determines which materials exhibit\nshear bands based on the initial conditions alone. We also show that the shear\nband width is not set by an inherent diffusion length scale but instead by a\ndynamical scale that depends on the imposed strain rate."
    },
    {
        "anchor": "From a microscopic inertial active matter model to the Schr\u00f6dinger\n  equation: Field theories for the one-body density of an active fluid, such as the\nparadigmatic active model B+, are simple yet very powerful tools for describing\nphenomena such as motility-induced phase separation. No comparable theory has\nbeen derived yet for the underdamped case. In this work, we introduce active\nmodel I+, an extension of active model B+ to particles with inertia. The\ngoverning equations of active model I+ are systematically derived from the\nmicroscopic Langevin equations. We show that, for underdamped active particles,\nthermodynamic and mechanical definitions of the velocity field no longer\ncoincide and that the density-dependent swimming speed plays the role of an\neffective viscosity. Moreover, active model I+ contains the Schr\\\"odinger\nequation in Madelung form as a limiting case, allowing to find analoga of the\nquantum-mechanical tunnel effect and of fuzzy dark matter in the active fluid.\nWe investigate the active tunnel effect analytically and via numerical\ncontinuation.",
        "positive": "Theory of photoinduced charge transfer in weakly coupled donor-acceptor\n  conjugated polymers: application to an MEH-PPV:CN-PPV pair: In a pair of coupled donor-acceptor conjugated polymer chains, it is possible\nfor an exciton photoexcited on either polymer to decay into a hole in the donor\npolymer's valence band and an electron in the conduction band of the acceptor\npolymer. We calculate the corresponding exciton decay rate and its dependence\non inter-polymer distance. For a pair of derivatives of poly(phenylene\nvinylene), PPV, specifically poly[2-methoxy, 5-(2$^\\prime$-ethyl-hexyloxy)-1, 4\nPPV], MEH-PPV, and poly(2,5-hexyloxy $p$-phenylene cyanovinylene), CN-PPV, at a\nseparation of 6 \\AA the characteristic decay time is 2.2 ps, whereas at 4 \\AA\nit is $\\sim 50$ fs."
    },
    {
        "anchor": "Nonadditive Interactions Unlock Small-Particle Mobility in Binary\n  Colloidal Monolayers: We examine the organization and dynamics of binary colloidal monolayers\ncomposed of micron-scale silica particles interspersed with smaller-diameter\nsilica particles that serve as minority component impurities. These binary\nmonolayers are prepared at the surface of ionic liquid droplets over a range of\nsize ratios ($\\sigma=0.16-0.66$) and are studied with low-dose minimally\nperturbative scanning electron microscopy (SEM). The high resolution of SEM\nimaging provides direct tracking of all particle coordinates over time,\nenabling a complete description of the microscopic state. In these bidisperse\nsize mixtures, particle interactions are non-additive because interfacial\npinning to the droplet surface causes the equators of differently sized\nparticles to lie in separate planes. By varying the size ratio we control the\nextent of non-additivity in order to achieve phase behavior inaccessible to\nadditive 2D systems. Across the range of size ratios we tune the system from a\nmobile small-particle phase ($\\sigma<0.24$), to an interstitial solid\n($0.24<\\sigma<0.33$), to a disordered glass ($\\sigma>0.33$). These distinct\nphase regimes are classified through measurements of hexagonal ordering of the\nlarge-particle host lattice and the lattice's capacity for small-particle\ntransport. Altogether, we explain these structural and dynamic trends by\nconsidering the combined influence of interparticle interactions and the\ncolloidal packing geometry. Our measurements are reproduced in molecular\ndynamics simulations of 2D non-additive disks, suggesting an efficient method\nfor describing confined systems with reduced dimensionality representations.",
        "positive": "Does Fluctuating Nonlinear Hydrodynamics Support an Ergodic-Nonergodic\n  Transition?: Despite its appeal, real and simulated glass forming systems do not undergo\nan ergodic-nonergodic (ENE) transition. We reconsider whether the fluctuating\nnonlinear hydrodynamics (FNH) model for this system, introduced by us in 1986,\nsupports an ENE transition. Using nonperturbative arguments, with no reference\nto the hydrodynamic regime, we show that the FNH model does not support an ENE\ntransition. Our results support the findings in the original paper. Assertions\nin the literature questioning the validity of the original work are shown to be\nin error."
    },
    {
        "anchor": "On the Bending Energy of Buckled Edge-Dislocations: The study of elastic membranes carrying topological defects has a\nlongstanding history, going back at least to the 1950s. When allowed to buckle\nin three-dimensional space, membranes with defects can totally relieve their\nin-plane strain, remaining with a bending energy, whose rigidity modulus is\nsmall compared to the stretching modulus. In this paper, we study membranes\nwith a single edge-dislocation. We prove that the minimum bending energy\nassociated with strain-free configurations diverges logarithmically with the\nsize of the system.",
        "positive": "Poiseuille flow of soft glasses in narrow channels: From quiescence to\n  steady state: Using numerical simulations, the onset of Poiseuille flow in a confined soft\nglass is investigated. Starting from the quiescent state, steady flow sets in\nat a time scale which increases with a decrease in applied forcing. At this\nonset time scale, a rapid transition occurs via the simultaneous fluidization\nof regions having different local stresses. In the absence of steady flow at\nlong times, creep is observed even in regions where the local stress is larger\nthan the bulk yielding threshold. Finally, we show that the time scale to\nattain steady flow depends strongly on the history of the initial state."
    },
    {
        "anchor": "On the mechanism of the highly viscous flow: The asymmetry model for the highly viscous flow postulates thermally\nactivated jumps from a practically undistorted ground state to strongly\ndistorted, but stable structures, with a pronounced Eshelby backstress from the\ndistorted surroundings. The viscosity is ascribed to those stable distorted\nstructures which do not jump back, but relax by the relaxation of the\nsurrounding viscoelastic matrix. It is shown that this mechanism implies a\ndescription in terms of the shear compliance, with a viscosity which can be\ncalculated from the cutoff of the retardation spectrum. Consistency requires\nthat this cutoff lies close to the Maxwell time. The improved asymmetry model\ncompares well with experiment.",
        "positive": "Quantum Field Theory of Treasury Bonds: The Heath-Jarrow-Morton (HJM) formulation of treasury bonds in terms of\nforward rates is recast as a problem in path integration. The HJM-model is\ngeneralized to the case where all the forward rates are allowed to fluctuate\nindependently. The resulting theory is shown to be a two-dimensional Gaussian\nquantum field theory. The no arbitrage condition is obtained and a functional\nintegral derivation is given for the price of a futures and an options\ncontract."
    },
    {
        "anchor": "Observation of total omnidirectional reflection from a one-dimensional\n  dielectric lattice: We show that under certain conditions one-dimensional dielectric lattice\npossesses total omnidirectional reflection of incident light. The predictions\nare verified experimentally using Na3AlF6/ZnSe multilayer structure developed\nby means of standard optical technology. The structure was found to exhibit\nreflection coefficient more then 99% in the range of incident angles 0-86\n(degree) at the wavelength of 632.8 nm for s-polarization. The results are\nbelieved to stimulate new experiments on photonic crystals and controlled\nspontaneous emission.",
        "positive": "Statics and dynamics of magnetocapillary bonds: When ferromagnetic particles are suspended at an interface under magnetic\nfields, dipole-dipole interactions compete with capillary attraction. This\ncombination of forces has recently given promising results towards controllable\nself-assemblies, as well as low Reynolds swimming systems. The elementary unit\nof these assemblies is a pair of particles. Although equilibrium properties of\nthis interaction are well described, dynamics remain unclear. In this letter,\nthe properties of magnetocapillary bonds are determined by probing them with\nmagnetic perturbations. Two deformation modes are evidenced and discussed.\nThese modes exhibit resonances whose frequencies can be detuned to generate\nnon-reciprocal motion. A model is proposed which can become the basis for\nelaborate collective behaviours."
    },
    {
        "anchor": "Surface wrinkling of an elastic block subject to biaxial loading by an\n  energy method: Wrinkles are often observed on the surfaces of compressed soft materials in\nnature. In the past few decades, the fascinating surface patterns have been\nstudied extensively by using the linear bifurcation analysis under plane\nstrain. The bifurcation concerns the non-uniqueness solutions, however, it\ndelivers little information about the surface instability before and after the\nthreshold. In this paper, we study surface wrinkling of a finite elastic block\nof general elastic materials subject to biaxial loading by an energy method.\nThe first and second variations of the strain energy functional are\nsystematically studied, and an eigenvalue problem is proposed whether the\nsecond variation is positive definite. We illustrate our analysis by using\nneo-Hookean materials as an example. Accordingly, we show that the initially\nflat state has the lowest energy and is stable before the stretches reach the\nthreshold at which the surface wrinkling occurs. We also find that the\nthreshold is independent of the size of the block and coincides with that of\nthe surface instability of an elastic half-space studied by Biot (1963) with\nthe linear bifurcation analysis. However, the stability region cannot be\nobtained by using the linear stability analysis. In contrast to the\nsize-independent threshold, the wavelength of surface wrinkling depends on the\nsize of the block. We first show that a two-dimensional rather than a\nthree-dimensional perturbation has lower energy and is more likely to trigger\nthe surface wrinkling in the instability region. The same stretch threshold of\na finite block and a half-space could shed light on the relation of surface\ninstabilities between finite and infinite bodies.",
        "positive": "Hydrodynamic interaction between two elastic microswimmers: We investigate the hydrodynamic interaction between two elastic swimmers\nwhich are composed of three spheres and two harmonic springs. In this model,\nthe natural length of each spring is assumed to undergo a prescribed cyclic\nchange, representing internal states of the swimmer [K. Yasuda et al., J. Phys.\nSoc. Jpn. 86, 093801 (2017)]. We obtain the average velocities of two identical\nelastic swimmers as a function of the distance between them both for\nstructurally asymmetric and symmetric swimmers. We show that the mean velocity\nof the two swimmers is always smaller than that of a single elastic swimmer.\nThe swimming state of two swimmers can be either bound or unbound depending on\nthe relative phase difference between the two elastic swimmers."
    },
    {
        "anchor": "Superdiffusion and non-Gaussian statistics in a driven-dissipative 2D\n  dusty plasma: Anomalous diffusion and non-Gaussian statistics are detected experimentally\nin a two-dimensional driven-dissipative system. A single-layer dusty plasma\nsuspension with a Yukawa interaction and frictional dissipation is heated with\nlaser radiation pressure to yield a structure with liquid ordering. Analyzing\nthe time series for mean-square displacement (MSD), superdiffusion is detected\nat a low but statistically significant level over a wide range of temperature.\nThe probability distribution function (PDF) fits a Tsallis distribution,\nyielding q, a measure of non-extensivity for non-Gaussian statistics.",
        "positive": "Synthetic Diamond and Wurtzite Structures Self-Assemble with Isotropic\n  Pair Interactions: Using inverse statistical-mechanical optimization techniques, we have\ndiscovered isotropic pair interaction potentials with strongly repulsive cores\nthat cause the tetrahedrally coordinated diamond and wurtzite lattices to\nstabilize, as evidenced by lattice sums, phonon spectra, positive-energy\ndefects, and self-assembly in classical molecular dynamics simulations. These\nresults challenge conventional thinking that such open lattices can only be\ncreated via directional covalent interactions observed in nature. Thus, our\ndiscovery adds to fundamental understanding of the nature of the solid state by\nshowing that isotropic interactions enable the self-assembly of open crystal\nstructures with a broader range of coordination number than previously thought.\nOur work is important technologically because of its direct relevance generally\nto the science of self-assembly and specifically to photonic crystal\nfabrication."
    },
    {
        "anchor": "Dynamics of oblique impact in a photoelastic granular medium: When a solid projectile impacts a granular target, it experiences a drag\nforce and abruptly comes to rest as its momentum transfers to the grains. An\nempirical drag force law successfully describes the force experienced by the\nprojectile, and the corresponding grain-scale mechanisms have been deciphered\nfor normal impacts. However, there is little work exploring non-normal impacts.\nAccordingly, we extend studies to explore oblique impact, in which a\nsignificant horizontal component of the drag force is present. In our\nexperiments, a projectile impacts a quasi-two-dimensional bed of bidisperse\nphotoelastic grains. We use high-speed imaging to measure high-resolution\nposition data of the projectile trajectory and simultaneously visualize\nparticle-scale force propagation in the granular medium. When the impact angle\nbecomes important, the spatial structure of the stress response reveals\nrelatively weak force chain propagation in the horizontal direction. Based on\nthese observations, we describe the decrease of the inertial drag force with\nimpact angle.",
        "positive": "Concentrated phase emulsion with multi-core morphology under shear: A\n  numerical study: We numerically study the dynamic behavior under a symmetric shear flow of\nselected examples of concentrated phase emulsions with multi-core morphology\nconfined within a microfluidic channel. A variety of new nonequilibrium steady\nstates is reported. Under low shear rates, the emulsion is found to exhibit a\nsolid-like behavior, in which cores display a periodic planetary-like motion\nwith approximately equal angular velocity. At higher shear rates two steady\nstates emerge, one in which all inner cores align along the flow and become\nessentially motionless and a further one in which some cores accumulate near\nthe outer interface and produce a dynamical elliptical-shaped ring chain,\nreminiscent of a treadmilling-like structure, while others occupy the center of\nthe emulsion. A quantitative description in terms of i) motion of the cores,\nii) rate of deformation of the emulsion and iii) structure of the fluid flow\nwithin the channel is also provided."
    },
    {
        "anchor": "Scaling theory for diffusion limited cluster aggregation in a porous\n  medium: A scaling theory is developed for diffusion-limited cluster aggregation in a\nporous medium, where the primary particles and clusters stick irreversibly to\nthe walls of the pore space as well as to each other. Three scaling regimes are\npredicted, connected by smooth crossovers. The first regime is at low primary\nparticle concentrations where the primary particles stick individually to the\nwalls. The second regime is at intermediate concentrations where clusters grow\nto a certain size, smaller than the pore size, then stick individually to the\nwalls. The third regime is at high concentrations where the final state is a\npore-space-filling network.",
        "positive": "Phase Separation by Entanglement of Active Polymerlike Worms: We investigate the aggregation and phase separation of thin, living T.\ntubifex worms that behave as active polymers. Randomly dispersed active worms\nspontaneously aggregate to form compact, highly entangled blobs, a process\nsimilar to polymer phase separation, and for which we observe power-law growth\nkinetics. We find that the phase separation of active polymerlike worms does\nnot occur through Ostwald ripening, but through active motion and coalescence\nof the phase domains. Interestingly, the growth mechanism differs from\nconventional growth by droplet coalescence: the diffusion constant\ncharacterizing the random motion of a worm blob is independent of its size, a\nphenomenon that can be explained from the fact that the active random motion\narises from the worms at the surface of the blob. This leads to a fundamentally\ndifferent phase-separation mechanism that may be unique to active polymers."
    },
    {
        "anchor": "Reentrant glass transition in a colloid-polymer mixture with depletion\n  attractions: Performing light scattering experiments we show that introducing short-ranged\nattraction to a colloidal suspension of nearly hard spheres by addition of free\npolymer produces new glass transition phenomena. We observe a dramatic\nacceleration of the density fluctuations amounting to the melting of a\ncolloidal glass. Increasing the strength of the attractions the system freezes\ninto another nonergodic state sharing some qualitative features with gel states\noccurring at lower colloid packing fractions. This reentrant glass transition\nis in qualitative agreement with recent theoretical predictions.",
        "positive": "Emergence of compact-disordered phase in a polymer Potts model: One of the central problems in epigenetics is how epigenetic modification\npatterns and chromatin structure are regulated in the cell nucleus. The polymer\nPotts model, a recently studied model of chromatins, is introduced with an\noffset in the interaction energy as a parameter, and the equilibrium properties\nare investigated using the mean-field analysis of the lattice model and\nmolecular dynamics simulations of the off-lattice model. The results show that\nin common with both models, a phase emerges, which could be called the\ncompact-disordered phase, in which the polymer conformation is compact and the\nepigenetic modification pattern is disordered, depending on the offset in the\ninteraction energy and the fraction of the modified nucleosomes."
    },
    {
        "anchor": "Directed self-assembly of spherical caps via confinement: In this work we use Monte Carlo simulations to study the phase behavior of\nspherical caps confined between two parallel hard walls separated by a distance\nH. The particle model consists of a hard sphere of diameter \\sigma cut off by a\nplane at a height \\chi, and it is loosely based on mushroom cap-shaped\nparticles whose phase behavior was recently studied experimentally [E. K. Riley\nand C. M. Liddell, Langmuir, 26, 11648 (2010)]. The geometry of the particles\nis characterized by the reduced height \\chi^* = \\chi/\\sigma, such that the\nmodel extrapolates between hard spheres for \\chi^* \\leftarrow 1 and infinitely\nthin hard platelets for \\chi^* \\letfarrow 0. Three different particle shapes\nare investigated: (a) three-quarter height spherical caps (\\chi^* = 3/4), (b)\none-half height spherical caps or hemispheres (\\chi^* = 1/2), and (c)\none-quarter height spherical caps (\\chi^* = 1/4). These three models are used\nto rationalize the effect of particle shape, obtained by cutting off spheres at\ndifferent heights, on the entropy-driven self-assembly of the particles under\nstrong confinements; i.e., for 1 < H/\\chi < 2.5. As H is varied, a sequence of\ncrystal structures are observed, including some having similar symmetry as that\nof the structures observed in confined hard spheres on account of the remaining\nspherical surface in the particles, but with additional features on account of\nthe particle shapes having intrinsic anisotropy and orientational degrees of\nfreedom. The \\chi^* = 3/4 system is found to exhibit a phase diagram that is\nmost similar to the one obtained experimentally for the confined mushroom\ncap-shaped colloidal particles under. A qualitative global phase diagram is\nconstructed that helps reveal the interrelations among different phases for all\nthe particle shapes and confinements studied.",
        "positive": "Attraction of Meso-Scale Objects on the Surface of a Thin Elastic Film\n  Supported on a Liquid: We study the interaction of two parallel rigid cylinders on the surface of a\nthin elastic film supported on a pool of liquid. The excess energy of the\nsurface due to the curvature of the stretched film induces attraction of the\ncylinders that can be quantified by the variation of their gravitational\npotential energies as they descend into the liquid while still floating on the\nfilm. Although the experimental results follow the trend predicted from the\nbalance of the gravitational and elastic energies of the system, they are\nsomewhat underestimated. The origin of this discrepancy is the hysteresis of\nadhesion between the cylinder and the elastic film that does not allow the\nconversion of the total available energy into gravitational potential energy as\nsome part of it is recovered in stretching the film behind the cylinders while\nthey approach each other. A modification of the model accounting for the\neffects of adhesion hysteresis improves the agreement between theoretical and\nexperimental results. The contribution of the adhesion hysteresis can be\nreduced considerably by introducing a thin hydrogel layer atop the elastic film\nthat enhances the range of attraction of the cylinders (as well as rigid\nspheres) in a dramatic way. Morphological instabilities in the gel project\ncorrugated paths to the motion of small spheres, thus leading to a large\nnumbers of particles to aggregate along their defects. These observations\nsuggest that a thin hydrogel layer supported on a deformable elastic film\naffords an effective model system to study elasticity and defects mediated\ninteraction of particles on its surface."
    },
    {
        "anchor": "Smectic Polymer Vesicles: Polymer vesicles are stable robust vesicles made from block copolymer\namphiphiles. Recent progress in the chemical design of block copolymers opens\nup the exciting possibility of creating a wide variety of polymer vesicles with\nvarying fine structure, functionality and geometry. Polymer vesicles not only\nconstitute useful systems for drug delivery and micro/nano-reactors but also\nprovide an invaluable arena for exploring the ordering of matter on curved\nsurfaces embedded in three dimensions. By choosing suitable liquid-crystalline\npolymers for one of the copolymer components one can create vesicles with\nsmectic stripes. Smectic order on shapes of spherical topology inevitably\npossesses topological defects (disclinations) that are themselves distinguished\nregions for potential chemical functionalization and nucleators of vesicle\nbudding. Here we report on glassy striped polymer vesicles formed from\namphiphilic block copolymers in which the hydrophobic block is a smectic liquid\ncrystal polymer containing cholesteryl-based mesogens. The vesicles exhibit\ntwo-dimensional smectic order and are ellipsoidal in shape with defects, or\npossible additional budding into isotropic vesicles, at the poles.",
        "positive": "Fluctuation profiles in inhomogeneous fluids: Three one-body profiles that correspond to local fluctuations in energy, in\nentropy, and in particle number are used to describe the equilibrium properties\nof inhomogeneous classical many-body systems. Local fluctuations are obtained\nfrom thermodynamic differentiation of the density profile or equivalently from\naverage microscopic covariances. The fluctuation profiles follow from\nfunctional generators and they satisfy Ornstein-Zernike relations. Computer\nsimulations reveal markedly different fluctuations in confined fluids with\nLennard-Jones, hard sphere, and Gaussian core interactions."
    },
    {
        "anchor": "Time dependent correlations in a supercooled liquid from nonlinear\n  fluctuating hydrodynamics: We solve numerically the equations of nonlinear fluctuating hydrodynamics\n(NFH) for the supercooled liquid. The time correlation of the density\nfluctuations in equilibrium obtained here shows quantitative agreement with\nmolecular dynamics(MD) simulation data. We demonstrate numerically that the\n1/rho nonlinearity in the NFH equations of motion is essential in restoring the\nergodic behavior in the liquid. Under nonequilibrium conditions the time\ncorrelation functions relax in a manner similar to that observed in the\nmolecular dynamics simulations in binary mixtures. The waiting time t_w\ndependence of the non-equilibrium response function follows a Modified\nKohlrausch-Williams-Watts(MKWW) form similar to the behavior seen in dielectric\nrelaxation data.",
        "positive": "Dynamics of cracks in disordered materials: Predicting when rupture occurs or cracks progress is a major challenge in\nnumerous elds of industrial, societal and geophysical importance. It remains\nlargely unsolved: Stress enhancement at cracks and defects, indeed, makes the\nmacroscale dynamics extremely sensitive to the microscale material disorder.\nThis results in giant statistical uctuations and non-trivial behaviors upon\nupscaling dicult to assess via the continuum approaches of engineering. These\nissues are examined here. We will see: How linear elastic fracture mechanics\nsidetracks the diculty by reducing the problem to that of the propagation of a\nsingle crack in an eective material free of defects, How slow cracks sometimes\ndisplay jerky dynamics, with sudden violent events incompatible with the\nprevious approach, and how some paradigms of statistical physics can explain\nit, How abnormally fast cracks sometimes emerge due to the formation of\nmicrocracks at very small scales."
    },
    {
        "anchor": "Symmetry break in the eight bubble compaction: Geometry and mechanics have both a relevant role in determining the\nthree-dimensional packing of 8 bubbles displyaed in a foam structure. We assume\nthat the spatial arrangement of bubbles obeys a geometrical principle\nmaximizing the minimum mutual distance between the bubble centroids. The\ncompacted structure is then obtained by radially packing the bubbles under\nconstraint of volume conservation. We generate a polygonal tiling on the\ncentral sphere and peripheral bubbles with both flat and curved interfaces. We\nverify that the obtained polyhedra is optimal under suitable physical criteria.\nFinally, we enforce the mechanical balance imposing the constraint of\nconservation of volume. We find an anisotropy in the distribution of the field\nof forces: surface tensions of bubble-bubble interfaces with normal oriented in\nthe circumferential direction of bubbles aggregate are larger than the ones\nwith normal unit vector pointing radially out of the aggregate. We suggest that\nthis mechanical cue is key for the symmetry break of this bubbles\nconfiguration.",
        "positive": "Velocity and density profiles of granular flow in channels using lattice\n  gas automaton: We have performed two-dimensional lattice-gas-automaton simulations of\ngranular flow between two parallel planes. We find that the velocity profiles\nhave non-parabolic distributions while simultaneously the density profiles are\nnon-uniform. Under non-slip boundary conditions, deviation of velocity profiles\nfrom the parabolic form of newtonian fluids is found to be characterized solely\nby ratio of maximal velocity at the center to the average velocity, though the\nratio depends on the model parameters in a complex manner. We also find that\nthe maximal velocity ($u_{max}$) at the center is a linear function of the\ndriving force (g) as $u_{max} = \\alpha g - \\delta$ with non-zero $\\delta$ in\ncontrast with newtonian fluids. Regarding density profiles, we observe that\ndensities near the boundaries are higher than those in the center. The width of\nhigher densities (above the average density) relative to the channel width is a\ndecreasing function of a variable which scales with the driving force (g),\nenergy dissipation parameter ($\\epsilon$) and the width of the system (L) as\n$g^{\\mu} L^{\\nu}/\\epsilon$ with exponents $\\mu = 1.4 \\pm 0.1$ and $\\nu = 0.5\n\\pm 0.1$. A phenomenological theory based on a scaling argument is presented to\ninterpret these findings."
    },
    {
        "anchor": "Transformation of polar nematic phases in the presence of electric field: Only a few years have passed since discovery of polar nematics, and now they\nare becoming the most actively studied liquid crystal materials. Despite\nnumerous breakthrough findings made recently, a theoretical systematization is\nstill lacking. In the present paper we are making a step on the way of\nsystematization. A powerful technique that molecular-statistical physics is has\nbeen applied to an assembly of polar molecules influenced by electric field.\nTotally, the three polar nematic phases were found to be stable at various\nconditions: the double-splay ferroelectric nematic $N_F^{2D}$ (observed in the\nlower-temperature range in the absence or at low electric field), the\ndouble-splay antiferroelectric nematic $N_{AF}$ (observed at intermediate\ntemperature in the absence or at low electric field) and the single-splay\nferroelectric nematic $N_F^{1D}$ (observed at moderate electric field at any\ntemperature below transition into paraelectric nematic $N$ and in the\nhigher-temperature range (also below $N$) at low electric field or without it.\nA paradoxal transition from $N_F^{1D}$ to $N$ induced by application of higher\nelectric field has been found and explained. A transformation of the structure\nof polar nematic phases at application of electric field has also been\ninvestigated by Monte Carlo simulations and experimentally by observation of\nPOM images. In particular, it has been realized that, at planar anchoring,\n$N_{AF}$ in the presence of moderate out-of-plane electric field exhibits the\ntwofold splay modulation: antiferroelectric in the plane of the substrate and\nferroelectric in the plane normal to the substrate. Several additional\nsub-transitions related to fitting confined geometry of the cell by the\nstructure of polar phases were detected.",
        "positive": "Anisotropic spatially heterogeneous dynamics on the $\u03b1$ and $\u03b2$\n  relaxation time scales studied via a four-point correlation function: We examine the anisotropy of a four-point correlation function\n$G_4(\\vec{k},\\vec{r};t)$ and it's associated structure factor\n$S_4(\\vec{k},\\vec{q};t)$ calculated using Brownian Dynamics computer\nsimulations of a model glass forming system. These correlation functions\nmeasure the spatial correlations of the relaxation of different particles, and\nwe examine the time and temperature dependence of the anisotropy. We find that\nthe anisotropy is strongest at nearest neighbor distances at time scales\ncorresponding to the peak of the non-Gaussian parameter $\\alpha_2(t) = 3 <\n\\delta r^4(t) >/[ 5 < \\delta r^2(t) >^2] - 1$, but is still pronounced around\nthe $\\alpha$ relaxation time. We find that the structure factor\n$S_4(\\vec{k},\\vec{q};t)$ is anisotropic even for the smallest wave vector\naccessible in our simulation suggesting that our system (and other systems\ncommonly used in computer simulations) may be too small to extract the $\\vec{q}\n\\to 0$ limit of the structure factor. We find that the determination of a\ndynamic correlation length from $S_4(\\vec{k},\\vec{q};t)$ is influenced by the\nanisotropy. We extract an effective anisotropic dynamic correlation length from\nthe small $q$ behavior of $S_4(\\vec{k},\\vec{q};t)$."
    },
    {
        "anchor": "Programming tunable active dynamics in a self-propelled robot: We present a scheme for producing tunable active dynamics in a self-propelled\nrobotic device. The robot moves using the differential drive mechanism where\ntwo wheels can vary their instantaneous velocities independently. These\nvelocities are calculated by equating robot's equations of motion in two\ndimensions with well-established active particle models and encoded into the\nrobot's microcontroller. We demonstrate that the robot can depict active\nBrownian, run and tumble, and Brownian dynamics with a wide range of\nparameters. The resulting motion analyzed using particle tracking shows\nexcellent agreement with the theoretically predicted trajectories. Finally, we\ndemonstrate that its motion can be switched between different dynamics using\nlight intensity as an external parameter. This work opens an avenue for\ndesigning tunable active systems with the potential of revealing the physics of\nactive matter and its application for bio- and nature-inspired robotics.",
        "positive": "Dynamic Density Functional Theory with Inertia and Background Flow: We present dynamic density functional theory (DDFT) incorporating general\ninhomogeneous, incompressible, time dependent background flows and inertia,\ndescribing externally driven passive colloidal systems out of equilibrium. We\nstart by considering the underlying nonequilibrium Langevin dynamics, including\nthe effect of the local velocity of the surrounding liquid bath, to obtain the\nnonlinear, nonlocal partial differential equations governing the evolution of\nthe (coarse--grained) density and velocity fields describing the dynamics of\ncolloids. Additionally, we show both with heuristic arguments, and by numerical\nsolution, that our equations and solutions agree with existing DDFTs in the\noverdamped (high friction) limit. We provide numerical solutions that model the\nflow of hard spheres, in both unbounded and confined domains, and compare to\npreviously--derived DDFTs with and without the background flow."
    },
    {
        "anchor": "Residual entropy and waterlike anomalies in the repulsive one\n  dimensional lattice gas: The thermodynamic and kinetics of the one dimensional lattice gas with\nrepulsive interaction is investigated using transfer matrix technique and Monte\nCarlo simulations. This simple model is shown to exhibit waterlike anomalies in\ndensity, thermal expansion coefficient and self diffusion. An unified\ndescription for the thermodynamic anomalies in this model is achieved based on\nthe ground state residual entropy which appears in the model due to mixing\nentropy in a ground state phase transition.",
        "positive": "Influence of pore-scale disorder on viscous fingering during drainage: We study viscous fingering during drainage experiments in linear Hele-Shaw\ncells filled with a random porous medium. The central zone of the cell is found\nto be statistically more occupied than the average, and to have a lateral width\nof 40% of the system width, irrespectively of the capillary number $Ca$. A\ncrossover length $w_f \\propto Ca^{-1}$ separates lower scales where the\ninvader's fractal dimension $D\\simeq1.83$ is identical to capillary fingering,\nand larger scales where the dimension is found to be $D\\simeq1.53$. The lateral\nwidth and the large scale dimension are lower than the results for Diffusion\nLimited Aggregation, but can be explained in terms of Dielectric Breakdown\nModel. Indeed, we show that when averaging over the quenched disorder in\ncapillary thresholds, an effective law $v\\propto (\\nabla P)^2$ relates the\naverage interface growth rate and the local pressure gradient."
    },
    {
        "anchor": "Multi-Self-Overlap Ensemble for protein folding: ground state search and\n  thermodynamics: Long chains of the HP lattice protein model are studied by the\nMulti-Self-Overlap Ensemble(MSOE) Monte Carlo method, which was developed\nrecently by the authors. MSOE successfully finds the lowest energy states\nreported before for sequences of the chain length $N=42\\sim 100$ in two and\nthree dimensions. Moreover, MSOE realizes the lowest energy state that ever\nfound in a case of N=100. Finite-temperature properties of these sequences are\nalso investigated by MSOE. Two successive transitions are observed between the\nnative and random coil states. Thermodynamic analysis suggests that the ground\nstate degeneracy is relevant to the order of the transitions in the HP model.",
        "positive": "Roughening, deroughening, and nonuniversal scaling of the interface\n  width in electrophoretic deposition of polymer chains: Growth and roughness of the interface of deposited polymer chains driven by a\nfield onto an impenetrable adsorbing surface are studied by computer\nsimulations in (2+1) dimensions. The evolution of the interface width W shows a\ncrossover from short-time growth described by the exponent beta1 to a long-time\ngrowth with exponent beta2 (>beta1). The saturated width increases, i.e., the\ninterface roughens, with the molecular weight Lc, but the roughness exponent\nalpha (from Ws~L^alpha) becomes negative in contrast to models for particle\ndeposition; alpha depends on the chain length--a nonuniversal scaling with the\nsubstrate length L. Roughening and deroughening occur as the field E and the\ntemperature T compete such that Ws=(A+BT)E^-1/2."
    },
    {
        "anchor": "Sliding friction in the hydrodynamic lubrication regime for a power-law\n  fluid: A scaling analysis is undertaken for the load balance in sliding friction in\nthe hydrodynamic lubrication regime, with a particular emphasis on power-law\nshear-thinning typical of a structured liquid. It is argued that the\nshear-thinning regime is mechanically unstable if the power-law index n < 1/2,\nwhere n is the exponent that relates the shear stress to the shear rate.\nConsequently the Stribeck (friction) curve should be discontinuous, with\npossible hysteresis. Further analysis suggests that normal stress and flow\ntransience (stress overshoot) do not destroy this basic picture, although they\nmay provide stabilising mechanisms at higher shear rates. Extensional viscosity\nis also expected to be insignificant unless the Trouton ratio is large. A\npossible application to shear thickening in non-Brownian particulate\nsuspensions is indicated.",
        "positive": "Conformations of Linear DNA: We examine the conformations of a model for under- and overwound DNA. The\nmolecule is represented as a cylindrically symmetric elastic string subjected\nto a stretching force and to constraints corresponding to a specification of\nthe link number. We derive a fundamental relation between the Euler angles that\ndescribe the curve and the topological linking number. Analytical expressions\nfor the spatial configurations of the molecule in the infinite- length limit\nwere obtained. A unique configuraion minimizes the energy for a given set of\nphysical conditions. An elastic model incorporating thermal fluctuations\nprovides excellent agreement with experimental results on the plectonemic\ntransition."
    },
    {
        "anchor": "Convective Motion in a Vibrated Granular Layer: Experimental results are presented for a vertically shaken granular layer. In\nthe range of accelerations explored, the layer develops a convective motion in\nthe form of one or more rolls. The velocity of the grains near the wall has\nbeen measured. It grows linearly with the acceleration, then the growing rate\nslows down. A rescaling with the amplitude of the wall velocity and the height\nof the granular layer makes all data collapse in a single curve. This can\nprovide insights on the mechanism driving the motion.",
        "positive": "Chemically symmetric and asymmetric self-driven rigid dumbbells in 2D\n  polymer gel: We employ computer simulations to unveil the translational and rotational\ndynamics of the self-driven chemically symmetric and asymmetric rigid dumbbells\nin two-dimensional polymer gel. Our results show that activity or the\nself-propulsion always enhances the dynamics of the dumbbells. Making the\nself-propelled dumbbell chemically asymmetric leads to further enhancement in\ndynamics. Additionally, the direction of self-propulsion is a key factor for\nthe chemically asymmetric dumbbells, where self-propulsion towards the\nnon-sticky half of the dumbbell results in faster translational and rotational\ndynamics compare to the case with the self-propulsion towards the sticky half\nof the dumbbell. Our analyses show that both the symmetric and asymmetric\npassive rigid dumbbells get trapped inside the mesh of the polymer gel, but the\nchemical asymmetry always facilitates mesh to mesh motion of the dumbbell and\nit is even more pronounced when the dumbbell is self-propelled. This results\nmultiple peaks in the van Hove function with increasing self-propulsion. In a\nnutshell, we believe that our in silico study can guide the researchers design\nefficient artificial microswimmers possessing potential applications in\nsite-specific delivery."
    },
    {
        "anchor": "Escape into the Third Dimension in Cholesteric Liquid Crystals: Integer winding disclinations are unstable in a nematic and are removed by an\n`escape into the third dimension', resulting in a non-singular texture. This\nprocess is frustrated in a cholesteric material due to the requirement of\nmaintaining a uniform handedness and instead results in the formation of\nstrings of point defects, as well as complex three-dimensional solitons such as\nheliknotons that consist of linked dislocations. We give a complete description\nof this frustration using methods of contact topology. Furthermore, we describe\nhow this frustration can be exploited to stabilise regions of the material\nwhere the handedness differs from the preferred handedness. These `twist\nsolitons' are stable in numerical simulation and are a new form of topological\ndefect in cholesteric materials that have not previously been studied.",
        "positive": "Phase transition induced hydrodynamic instability and Langmuir-Blodgett\n  Deposition: We propose a model to understand periodic oscillations relevant to the origin\nof mesoscopic channels formed during a Langmuir-Blodgett deposition observed in\nrecent experiments \\{M. Gleiche, L.F. Chi, and H. Fuchs, Nature {\\bf 403}, 173\n(2000)\\}. We numerically study one-dimensional flow of a van der Waals fluid\nnear its discontinuous liquid-gas transition and find that steady-state flow\nbecomes unstable in the vicinity of the phase transition. Instabilities leading\nto complex periodic density-oscillations are demonstrated at some suitably\nchosen sets of parameters."
    },
    {
        "anchor": "Emergent States in Systems of Chiral Self-Propelled Rods: We study inherently chiral self-propelled particles, self-rotating at a fixed\nfrequency, in two dimensions, subjected to nematic alignment interactions and\nrotational noise. By means of both, homogeneous and spatially resolved mean\nfield kinetic theory, we identify various different flocking states. We confirm\nthe presence of the predicted phases using agent-based simulations, in\nparticular, an homogeneous nematic phase at low frequencies, followed by a\nmicroflock pattern phase at larger frequencies, characterized by finite-size\nnematic clusters. We emphasize that special care has to be taken within the\nsimulations in order to avoid artifacts, and present a non-standard simulation\ntechnique in order to avoid them.",
        "positive": "Intermittent dilation and its coupling to stress in discontinuous shear\n  thickening suspensions: We investigate dilation-induced surface deformations in a Discontinuous Shear\nThickening (DST) suspension to determine the relationship between dilation and\nstresses in DST. Video is taken at two observation points on the surface of the\nsuspension in a rheometer while shear and normal stresses are measured. A\nroughened surface of the suspension is observed as particles poke through the\nliquid-air interface, corresponding to dilation. Dilation events are found to\nbe intermittent and localized spatially. Shear and normal stresses also\nfluctuate between high- and low-stress states, and dilation is observed\nfrequently in the high stress state. On the other hand, a complete lack of\ndilation is observed when the stresses remain at low values for a several\nseconds. Dilation is most prominent while the stresses grow from the low-stress\nstate to the high-stress state, and the dilated region tends to span the entire\nsurface by the end of the stress growth period. Dilation is found only at\nstresses and shear rates in and above the shear thickening range. These\nobserved relations between surface dilation and stresses confirm that dilation\nand stresses are coupled in the high-stress state of DST."
    },
    {
        "anchor": "Analytical characterization of adhering vesicles: We characterize vesicle adhesion onto homogeneous substrates by means of a\nperturbative expansion around the infinite adhesion limit, where curvature\nelasticity effects are absent. At first order in curvature elasticity, we\ndetermine analytically various global physical quantities associated with\nadhering vesicles: height, adhesion radius, etc. Our results are valid for\nadhesion energies above a certain threshold, that we determine numerically. We\ndiscuss the haptotactic force acting on a vesicle in the limit of weak adhesion\ngradients. We also propose novel methods for measuring adhesion energies and we\nsuggest a possible way of determining the size of suboptical vesicles using\ncontrolled adhesion gradients.",
        "positive": "Transition of a particle between adjacent optical traps: A study using\n  catastrophe theory: In spite of the widespread use of optical tweezers as a quantitative tool to\nmeasure small forces, there exists no unambiguous and simple experimental\nmethod for either validating its theoretically predicted form or empirically\nparameterizing it over the entire range. This problem is addressed by studying\nthe transition of a colloidal particle between two spatially separated optical\ntraps. The transition as a function of the relative intensity of the traps and\nthe separation between them reveals a formal resemblance to the `butterfly\ncatastrophe' which also maps onto to phase transitions observed, for example in\nferroelectrics, on a phenomenological level. The method has been used to\nexperimentally determine the force-displacement curve for an optical trap over\nits entire range."
    },
    {
        "anchor": "Propensity to form amyloid fibrils is encoded as excitations in the free\n  energy landscape of monomeric proteins: Protein aggregation, linked to many of diseases, is initiated when monomers\naccess rogue conformations that are poised to form amyloid fibrils. We show,\nusing simulations of src SH3 domain, that mechanical force enhances the\npopulation of the aggregation prone ($N^*$) states, which are rarely populated\nunder force free native conditions, but are encoded in the spectrum of native\nfluctuations. The folding phase diagrams of SH3 as a function of denaturant\nconcentration ($[C]$), mechanical force ($f$), and temperature exhibit an\napparent two-state behavior, without revealing the presence of the elusive\n$N^*$ states. Interestingly, the phase boundaries separating the folded and\nunfolded states at all [C] and $f$ fall on a master curve, which can can be\nquantitatively described using an analogy to superconductors in a magnetic\nfield. The free energy profiles as a function of the molecular extension ($R$),\nwhich are accessible in pulling experiments, ($R$), reveal the presence of a\nnative-like $N^*$ with a disordered solvent-exposed amino terminal\n$\\beta$-strand. The structure of the $N^*$ state is identical to that found in\nFyn SH3 by NMR dispersion experiments. We show that the time scale for fibril\nformation can be estimated from the population of the $N^*$ state, determined\nby the free energy gap separating the native structure and the $N^*$ state, a\nfinding that can be used to assess fibril forming tendencies of proteins. The\nstructures of the $N^*$ state are used to show that oligomer formation and\nlikely route to fibrils occur by a domain-swap mechanism in SH3 domain.",
        "positive": "Athermal rheology of weakly attractive soft particles: We study the rheology of a soft particulate system where the inter-particle\ninteractions are weakly attractive. Using extensive molecular dynamics\nsimulations, we scan across a wide range of packing fractions ($\\phi$),\nattraction strengths ($u$) and imposed shear-rates ($\\dot{\\gamma}$). In\nstriking contrast to repulsive systems, we find that at small shear-rates\ngenerically a fragile isostatic solid is formed even if we go to $\\phi \\ll\n\\phi_J$. Further, with increasing shear-rates, even at these low $\\phi$,\nnon-monotonic flow curves occur which lead to the formation of persistent\nshear-bands in large enough systems. By tuning the damping parameter, we also\nshow that inertia plays an important role in this process. Furthermore, we\nobserve enhanced particle dynamics in the attraction-dominated regime as well\nas a pronounced anisotropy of velocity and diffusion constant, which we take as\nprecursors to the formation of shear bands. At low enough $\\phi$, we also\nobserve structural changes via the interplay of low shear-rates and attraction\nwith the formation of micro-clusters and voids. Finally, we characterize the\nproperties of the emergent shear bands and thereby, we find surprisingly small\nmobility of these bands, leading to prohibitely long time-scales and extensive\nhistory effects in ramping experiments."
    },
    {
        "anchor": "Soft Sphere Packings at Finite Pressure but Unstable to Shear: When are athermal soft sphere packings jammed ? Any experimentally relevant\ndefinition must at the very least require a jammed packing to resist shear. We\ndemonstrate that widely used (numerical) protocols in which particles are\ncompressed together, can and do produce packings which are unstable to shear -\nand that the probability of generating such packings reaches one near jamming.\nWe introduce a new protocol that, by allowing the system to explore different\nbox shapes as it equilibrates, generates truly jammed packings with strictly\npositive shear moduli G. For these packings, the scaling of the average of G is\nconsistent with earlier results, while the probability distribution P(G)\nexhibits novel and rich scaling",
        "positive": "Statistical thermodynamics of adhesion points in supported membranes: Supported lipid membranes are useful and important model systems for studying\ncell membrane properties and membrane mediated processes. One attractive\napplication of supported membranes is the design of phantom cells exhibiting\nwell defined adhesive properties and receptor densities. Adhesion of membranes\nmay be achieved by specific and non-specific interactions, and typically\nrequires the clustering of many adhesion bonds into \"adhesion domains\". One\npotential mediator of the early stages of the aggregation process is the\nCasimir-type forces between adhesion sites induced by the membrane thermal\nfluctuations. In this review, I will present a theoretical analysis of\nfluctuation induced aggregation of adhesion sites in supported membranes. I\nwill first discuss the influence of a single attachment point on the spectrum\nof membrane thermal fluctuations, from which the free energy cost of the\nattachment point will be deduced. I will then analyze the problem of a\nsupported membrane with two adhesion points. Using scaling arguments and Monte\nCarlo simulations, I will demonstrate that two adhesion points attract each\nother via an infinitely long range effective potential that grows\nlogarithmically with the pair distance. Finally, I will discuss the many-body\nnature of the fluctuation induced interactions. I will show that while these\ninteractions alone are not sufficient to allow the formation of aggregation\nclusters, they greatly reduce the strength of the residual interactions\nrequired to facilitate cluster formation. Specifically, for adhesion molecules\ninteracting via a short range attractive potential, the strength of the direct\ninteractions required for aggregation is reduced by about a factor of two to\nbelow the thermal energy $k_BT$."
    },
    {
        "anchor": "Polymer translocation under time-dependent driving forces: resonant\n  activation induced by attractive polymer-pore interactions: We study the driven translocation of polymers under time-dependent driving\nforces using $N$-particle Langevin dynamics simulations. We consider the force\nto be either sinusoidally oscillating in time or dichotomic noise with\nexponential correlation time, to mimic both plausible experimental setups and\nnaturally occurring biological conditions. In addition, we consider both the\ncase of purely repulsive polymer-pore interactions and the case with additional\nattractive polymer-pore interactions, typically occurring inside biological\npores. We find that the nature of the interaction fundamentally affects the\ntranslocation dynamics. For the non-attractive pore, the translocation time\ncrosses over to a fast translocation regime as the frequency of the driving\nforce decreases. In the attractive pore case, because of a free energy well\ninduced inside the pore, the translocation time can be a minimum at the optimal\nfrequency of the force, the so-called resonant activation. In the latter case,\nwe examine the effect of various physical parameters on the resonant\nactivation, and explain our observations using simple theoretical arguments.",
        "positive": "The Influence of Network Topology on Sound Propagation in Granular\n  Materials: Granular materials, whose features range from the particle scale to the\nforce-chain scale to the bulk scale, are usually modeled as either particulate\nor continuum materials. In contrast with either of these approaches, network\nrepresentations are natural for the simultaneous examination of microscopic,\nmesoscopic, and macroscopic features. In this paper, we treat granular\nmaterials as spatially-embedded networks in which the nodes (particles) are\nconnected by weighted edges obtained from contact forces. We test a variety of\nnetwork measures for their utility in helping to describe sound propagation in\ngranular networks and find that network diagnostics can be used to probe\nparticle-, curve-, domain-, and system-scale structures in granular media. In\nparticular, diagnostics of meso-scale network structure are reproducible across\nexperiments, are correlated with sound propagation in this medium, and can be\nused to identify potentially interesting size scales. We also demonstrate that\nthe sensitivity of network diagnostics depends on the phase of sound\npropagation. In the injection phase, the signal propagates systemically, as\nindicated by correlations with the network diagnostic of global efficiency. In\nthe scattering phase, however, the signal is better predicted by meso-scale\ncommunity structure, suggesting that the acoustic signal scatters over local\ngeographic neighborhoods. Collectively, our results demonstrate how the force\nnetwork of a granular system is imprinted on transmitted waves."
    },
    {
        "anchor": "Invariant Theory and Orientational Phase Transitions: The Landau theory of phase transitions has been productively applied to phase\ntransitions that involve rotational symmetry breaking, such as the transition\nfrom an isotropic fluid to a nematic liquid crystal. It even can be applied to\nthe orientational symmetry breaking of simple atomic or molecular clusters that\nare not true phase transitions. In this paper we address fundamental problems\nthat arise with the Landau theory when it is applied to rotational symmetry\nbreaking transitions of more complex particle clusters that involve order\nparameters characterized by larger values of the $l$ index of the dominant\nspherical harmonic that describes the broken symmetry state. The problems are\ntwofold. First, one may encounter a thermodynamic instability of the expected\nground state with respect to states with lower symmetry. A second problem\nconcerns the proliferation of quartic invariants that may or may not be\nphysical. We show that the combination of a geometrical method based on the\nanalysis of the space of invariants, developed by Kim to study symmetry\nbreaking of the Higgs potential, with modern visualization tools provides a\nresolution to these problems. The approach is applied to the outcome of\nnumerical simulations of particle ordering on a spherical surface and to the\nordering of protein shells.",
        "positive": "Anisotropy driven dynamics in vibrated granular rods: The dynamics of a set of rods bouncing on a vertically vibrated plate is\ninvestigated using experiments, simulations, and theoretical analysis. The\nexperiments and simulations are performed within an annulus to impose periodic\nboundary conditions. Rods tilted with respect to the vertical are observed to\nspontaneously develop a horizontal velocity depending on the acceleration of\nthe plate. For high plate acceleration, the rods are observed to always move in\nthe direction of tilt. However, the rods are also observed to move opposite to\ndirection of tilt for a small range of plate acceleration and rod tilt. A phase\ndiagram of the observed motion is presented as a function of plate acceleration\nand the tilt of the rods which is varied by changing the number of rods inside\nthe annulus. Next we introduce a novel molecular dynamics method to simulate\nthe dynamics of the rods using the dimensions and dissipation parameters from\nthe experiments. We reproduce the observed horizontal rod speeds as a function\nof rod tilt and plate acceleration in the simulations. By decreasing the\nfriction between the rods and the base plate to zero in the simulation, we\nidentify the friction during the collision as the crucial ingredient for\noccurrence of the horizontal motion. Guided by the data from the experiments\nand the simulations, we construct a mechanical model for the dynamics of the\nrods in the limit of thin rods. The starting point of the analysis is the\ncollision of a single rod with an oscillating plate. Three friction regimes are\nidentified: slide, slip-stick, and slip reversal. A formula is derived for the\nobserved horizontal velocity as a function of tilt angle. Good agreement for\nthe horizontal velocity as a function of rod tilt and plate acceleration is\nfound between experiments, simulations and theory."
    },
    {
        "anchor": "Polymer Translocation througha Pore in a Membrane: We construct a new statistical physical model of polymer translocation\nthrough a pore in a membrane treated as the diffusion process across a free\nenergy barrier. We determine the translocation time in terms of chain\nflexibility yielding an entropic barrier, as well as in terms of the driving\nmechanisms such as transmembrane chemical potential difference and Brownian\nratchets. It turns out that, while the chemical potential differences induce\npronounced effects on translocation due to the long-chain nature of the\npolymer, the ratchets suppress this effect and chain flexibility.",
        "positive": "Short-chain polymer rigidity due to the Debye process of monohydroxy\n  alcohols: In addition to the ubiquitous structural relaxation of viscous supercooled\nliquids, monohydroxy alcohols and several other hydrogen-bonded systems display\na strong single-exponential electrical low-frequency absorption. So far, this\nso-called Debye process could be observed only using dielectric techniques.\nExploiting a combination of broad-band and high-resolution rheology experiments\nfor three isomeric octanols, unambiguous mechanical evidence for the Debye\nprocess is found. Its spectral signature is similar to the viscoelastic\nfingerprint of small-chain polymers, enabling us to estimate the effective\nmolecular weight for the supramolecular structure formed by the studied\nmonohydroxy alcohols. This finding opens the venue for the application of\nfurther non-dielectric techniques directed at unraveling the microscopic nature\nof the Debye process and for an understanding of this phenomenon in terms of\npolymer concepts."
    },
    {
        "anchor": "Review on Generalized Dynamics of Soft-Matter Quasicrystals and Its\n  Applications: This article provides a detailed review on the generalized dynamics of\nsoft-matter quasicrystals developed recent years. Comparing to solid\nquasicrystals consisted mainly with metallic alloys, soft-matter quasicrystals\nhave been observed in liquid crystals, polymers, colloids, nanoparticles, and\nsurfactants, which indicate quite different formation mechanism. Based on\nLandau-Anderson theory and group representation theory, we have studied the\nsymmetry, symmetry breaking and elementary excitations for the observed and\npossible soft-matter quasicrystals. We further proposed one more elementary\nexcitation: fluid phonon additional to the phonon and phason for solid\nquasicrystals, to quantitatively describe the dynamics of soft-matter\nquasicrystals. The general governing equations and the solutions of the\ndynamics evolution on the distribution, deformation and motion of the new phase\nare studied, which reveal quite distinguishing dynamic behavior with those of\nconventional fluids and solid quasicrystals. Some applications are introduced,\nwhich show this is an important field of new materials and materials science.",
        "positive": "A Strong Bond Model for Stress Relaxation of Soft Solid Interfaces: In this article, we propose a mathematical model which explains the formation\nof strong bonds during the relaxation process of a soft solid on a hard\nsurface. As a result, the soft solid relaxes to a non zero residual stress\nlevel. The model assumes that formation of strong bonds occurs owing to\ntransition from weak to strong bonds at a critical time. Parametric studies are\ncarried out to understand the effect of different friction parameters related\nwith the model on the relaxation process. The relaxation model is, in turn,\nvalidated with experiments and corresponding numerical values are justified."
    },
    {
        "anchor": "Competing Interactions among Supramolecular Structures on Surfaces: A simple model was constructed to describe the polar ordering of\nnon-centrosymmetric supramolecular aggregates formed by self assembling\ntriblock rodcoil polymers. The aggregates are modeled as dipoles in a lattice\nwith an Ising-like penalty associated with reversing the orientation of nearest\nneighbor dipoles. The choice of the potentials is based on experimental results\nand structural features of the supramolecular objects. For films of finite\nthickness, we find a periodic structure along an arbitrary direction\nperpendicular to the substrate normal, where the repeat unit is composed of two\nequal width domains with dipole up and dipole down configuration. When a short\nrange interaction between the surface and the dipoles is included the balance\nbetween the up and down dipole domains is broken. Our results suggest that due\nto surface effects, films of finite thickness have a none zero macroscopic\npolarization, and that the polarization per unit volume appears to be a\nfunction of film thickness.",
        "positive": "Fast, scalable, and interactive software for Landau-de Gennes numerical\n  modeling of nematic topological defects: Numerical modeling of nematic liquid crystals using the tensorial Landau-de\nGennes (LdG) theory provides detailed insights into the structure and\nenergetics of the enormous variety of possible topological defect\nconfigurations that may arise when the liquid crystal is in contact with\ncolloidal inclusions or structured boundaries. However, these methods can be\ncomputationally expensive, making it challenging to predict (meta)stable\nconfigurations involving several colloidal particles, and they are often\nrestricted to system sizes well below the experimental scale. Here we present\nan open-source software package that exploits the embarrassingly parallel\nstructure of the lattice discretization of the LdG approach. Our\nimplementation, combining CUDA/C++ and OpenMPI, allows users to accelerate\nsimulations using both CPU and GPU resources in either single- or multiple-core\nconfigurations. We make use of an efficient minimization algorithm, the Fast\nInertial Relaxation Engine (FIRE) method, that is well-suited to large-scale\nparallelization, requiring little additional memory or computational cost while\noffering performance competitive with other commonly used methods. In\nmulti-core operation we are able to scale simulations up to supra-micron length\nscales of experimental relevance, and in single-core operation the simulation\npackage includes a user-friendly GUI environment for rapid prototyping of\ninterfacial features and the multifarious defect states they can promote. To\ndemonstrate this software package, we examine in detail the competition between\ncurvilinear disclinations and point-like hedgehog defects as size scale,\nmaterial properties, and geometric features are varied. We also study the\neffects of an interface patterned with an array of topological point-defects."
    },
    {
        "anchor": "Maximally localized Wannier functions from PAW or ultrasoft\n  pseudopotentials: We report a theoretical scheme that enables the calculation of maximally\nlocalized Wannier functions in the formalism of projector-augmented-waves (PAW)\nwhich also includes the ultrasoft-pseudopotential (USPP) approach. We give a\ndescription of the basic underlying formalism and explicitly write all the\nrequired matrix elements from the common ingredients of the PAW/USPP theory. We\nreport an implementation of the method in a form suitable to accept the input\nelectronic structure from USPP plane-wave DFT simulations. We apply the method\nto the calculation of Wannier functions, dipole moments and spontaneous\npolarizations in a range of test cases. Comparison with norm-conserving\npseudopotentials is reported as a benchmark.",
        "positive": "Differential stability of DNA based on salt concentration: Intracellular positive ions neutralise negative charges on the phosphates of\na DNA strand conferring greater strength on the hydrogen bonds that connect\ncomplementary strands into a double helix and so confer enhanced stability.\nBeyond a certain value of salt concentration, the DNA molecule displays a\nunstable nature {\\it in vivo} as well as {\\it in vitro}. We consider a wide\nrange of salt concentrations and study the stability of the DNA double helix\nusing a statistical model. Through numerical calculations we attempt to explain\nthe different behaviour exhibited by DNA molecules in this range. We compare\nour results with experimental data and find a close agreement."
    },
    {
        "anchor": "Pressure densification of a simple liquid: The magnitude of the high frequency, static dielectric permittivity is used\nto determine the density of tetramethyl tetraphenyl trisiloxane, a\nnon-associated glass-forming liquid, as a function of temperature and pressure.\nWe demonstrate that the properties in the glassy state are affected by the\npressure applied to the liquid during vitrification. This behavior is normal\nfor hydrogen-bonded liquids and polymers, but unanticipated by models of simple\nliquids.",
        "positive": "Attractive interaction and bridging transition between neutral colloidal\n  particles due to preferential adsorption in a near-critical binary mixture: We examine the solvent-mediated interaction between two neutral colloidal\nparticles due to preferential adsorption in a near-critical binary mixture. We\ntake into account the renormalization effect due to the critical fluctuations\nusing the recent local functional theory $[$J. Chem. Phys. {\\bf 136}, 114704\n(2012)$]$. We calculate the free energy and the force between two colloidal\nparticles as functions of the temperature $T$, the composition far from the\ncolloidal particles $c_\\infty$, and the colloid separation $\\ell$. The\ninteraction is much enhanced when the component favored by the colloid surfaces\nis poor in the reservoir. For such off-critical compositions, we find a surface\nof a first-order bridging transition $\\ell= \\ell_{\\rm cx}(T,c_\\infty)$ in the\n$T$-$c_\\infty$-$\\ell$ space in a universal, scaled form, across which a\ndiscontinuous change occurs between separated and bridged states. This surface\nstarts from the bulk coexistence surface (CX) and ends at a bridging critical\nline $\\ell= \\ell_{c}(T)$. On approaching the critical line, the discontinuity\nvanishes and the derivatives of the force with respect to $T$ and $\\ell$ both\ndiverge. Furthermore, bridged states continuously change into separated states\nif $c_\\infty$ (or $T$) is varied from a value on CX to value far from CX with\n$\\ell$ kept smaller than $\\ell_c(T)$."
    },
    {
        "anchor": "The free energy of a liquid when viewed as a population of overlapping\n  clusters: The expression of the free energy of a liquid in terms of an explicit\ndecomposition of the particle configurations into local coordination clusters\nis examined. We argue that the major contribution to the entropy associated\nwith structural fluctuations arises from the local athermal constraints imposed\nby the overlap of adjacent coordination shells. In the context of the recently\ndeveloped Favoured Local Structure model [Soft Matt. 11, 3322 (2015)], we\nderive explicit expressions for the structural energy and entropy in the high\ntemperature limit, compare this approximation with simulation data and consider\nthe extension of this free energy to the case of spatial inhomogeneity in the\ndistribution of local structures.",
        "positive": "Size Effect on Reaction Rate of Surface Nanodroplets: Compartmentalizing reagents within small droplets is promising for highly\nefficient conversion and simplified procedures in many biphasic chemical\nreactions. In this work, surface nanodroplets (i.e., less than 100 nm in their\nmaximal height) were employed to quantitatively understand the size effect on\nthe chemical reaction rate of droplets. In our systems, a surface-active\nreactant in pure or binary nanodroplets reacted with the reactant in the bulk\nflow. Meanwhile, the product was removed from the droplet surface. The\nshrinkage rate of the nanodroplets was characterized by analyzing the lateral\nsize as a function of time, where the droplet size was solely determined by\nchemical reaction rate at a given flow condition for the transport of the\nreactant and the product. We found that the overall kinetics increases rapidly\nwith the decrease of droplets lateral radius R, as dR/dt ~ R^(-2). The faster\nincrease in the concentration of the product in smaller droplets contributes to\naccelerating reaction kinetics. The enhancement of reaction rates from small\ndroplet sizes was further confirmed when a non-reactive compound presented\ninside the droplets without reducing the concentrations of the reactant and the\nproduct on the droplet surface. The results of our study improve the\nunderstanding of chemical kinetics with droplets. Our findings highlight the\neffectiveness of small droplets for the design and control of enhanced chemical\nreactions in a broad range of applications."
    },
    {
        "anchor": "Molecular Rheology of Nanoconfined Polymer Melts: We use non-equilibrium atomistic molecular dynamics simulations of\nunentangled melts of linear and star polymers ($\\mathrm{C_{25}H_{52}}$) to\nstudy the steady-state viscoelastic response under confinement within nanoscale\nhematite $\\left ( \\mathrm{\\alpha-Fe_2O_3} \\right )$ channels. We report (i) the\nnegative (positive) first (second) normal stress difference and (ii) the\npresence of viscoelastic tension at low shear rates. We link these effects to\nbond alignment such that chains near the surface can carry the elastic force\nexerted on the walls, which decays as the chains become more aligned in the\nflow direction as the shear rate increases.",
        "positive": "Hypocycloidal Inclusions in Nonuniform Out-of-Plane Elasticity: Stress\n  Singularity vs. Stress Reduction: Stress field solutions and Stress Intensity Factors (SIFs) are found for\n$n$-cusped hypocycloidal shaped voids and rigid inclusions in an infinite\nlinear elastic plane subject to nonuniform remote antiplane loading, using\ncomplex potential and conformal mapping. It is shown that a void with\nhypocycloidal shape can lead to a higher SIF than that induced by a\ncorresponding star-shaped crack; this is counter intuitive as the latter\nusually produces a more severe stress field in the material. Moreover, it is\nobserved that when the order $m$ of the polynomial governing the remote loading\ngrows, the stress fields generated by the hypocycloidal-shaped void and the\nstar-shaped crack tend to coincide, so that they become equivalent from the\npoint of view of a failure analysis. Finally, special geometries and loading\nconditions are discovered for which there is no stress singularity at the\ninclusion cusps and where the stress is even reduced with respect to the case\nof the absence of the inclusion. The concept of Stress Reduction Factor (SRF)\nin the presence of a sharp wedge is therefore introduced, contrasting with the\nwell-known definition of Stress Concentration Factor (SCF) in the presence of\ninclusions with smooth boundary. The results presented in this paper provide\ncriteria that will help in the design of ultra strong composite materials,\nwhere stress singularities always promote failure. Furthermore, they will\nfacilitate finding the special conditions where resistance can be optimized in\nthe presence of inclusions with non-smooth boundary."
    },
    {
        "anchor": "A fluorescence correlation spectroscopy study of macromolecular tracer\n  diffusion in polymer solutions: We discuss the manner in which the dynamics of tracer polystyrene chains\nvaries with the concentration of matrix polystyrene chains dissolved in\ntoluene. Using fluorescence correlation spectroscopy and theory, it is shown\nthat the cooperative diffusion coefficient of the matrix polystyrene chains can\nbe measured by fluorescence correlation spectroscopy in the semidilute\nentangled concentration regime. In addition the self-diffusion coefficient of\nthe tracer polystyrene chains can be detected for arbitrary concentrations. The\nmeasured cooperative diffusion coefficient is independent of the molecular\nweight of the tracer polystyrene chains because it is a characteristic feature\nof the transient entanglement network.",
        "positive": "A fine balance of chemotactic and hydrodynamic torques: when\n  microswimmers orbit a pillar just once: We study the detention statistics of self-propelling droplet microswimmers\nattaching to microfluidic pillars. These droplets show negative autochemotaxis:\nthey shed a persistent repulsive trail of spent fuel that biases them to detach\nfrom pillars of a certain size after orbiting them just once. We have designed\na microfluidic assay recording swimmers in pillar arrays of varying diameter,\nderived detention statistics via digital image analysis and interpreted these\nstatistics via the Langevin dynamics of an active Brownian particle (ABP)\nmodel. By comparing data from orbits with and without residual chemical field,\nwe can independently estimate quantities like hydrodynamic and chemorepulsive\ntorques, chemical coupling constants and diffusion coefficients, as well as\ntheir dependence on boundary conditions like wall curvature."
    },
    {
        "anchor": "Low temperature physics at room temperature in water: Charge inversion\n  in chemical and biological systems: We review recent advances in the physics of strongly interacting charged\nsystems functioning in water at room temperature. We concentrate on the\nphenomena which go beyond the framework of mean field theories, whether linear\nDebye-Huckel or non-linear Poisson-Boltzmann. We place major emphasis on charge\ninversion - a counterintuitive phenomenon in which a strongly charged particle,\ncalled macroion, binds so many counterions that its net charge changes sign. We\ndiscuss the universal theory of charge inversion based on the idea of a\nstrongly correlated liquid of adsorbed counterions, similar to a Wigner\ncrystal. This theory has a vast array of applications, particularly in biology\nand chemistry; for example, the DNA double helix in the presence of positive\nmultivalent ions (e.g., polycations) acquires a net positive charge and drifts\nas a positive particle in electric field. This simplifies DNA uptake by the\ncell as needed for gene therapy, because the cell membrane is negatively\ncharged. We discuss also the analogies of charge inversion in other fields of\nphysics.",
        "positive": "Water-polymer coupling induces a dynamical transition in microgels: The long debated protein dynamical transition was recently found also in\nnon-biological macromolecules, such as poly-N-isopropylacrylamide (PNIPAM)\nmicrogels. Here, by using atomistic molecular dynamics simulations, we report a\ndescription of the molecular origin of the dynamical transition in these\nsystems. We show that PNIPAM and water dynamics below the dynamical transition\ntemperature Td are dominated by methyl group rotations and hydrogen bonding,\nrespectively. By comparing with bulk water, we unambiguously identify\nPNIPAM-water hydrogen bonding as the main responsible for the occurrence of the\ntransition. The observed phenomenology thus crucially depends on the\nwater-macromolecule coupling, being relevant to a wide class of hydrated\nsystems, independently from the biological function."
    },
    {
        "anchor": "Extreme cooperative swelling in topologically disordered fibre\n  entanglements: Entangled states are ubiquitous amongst fibrous materials, whether naturally\noccurring (keratin, collagen, DNA) or synthetic (nanotube assemblies,\nelastane). A key mechanical characteristic of these systems is their ability to\nreorganise in response to external stimuli, as implicated in e.g.\nhydration-induced swelling of keratin fibrils in human skin. During swelling,\nthe curvature of individual fibres changes to give a cooperative and reversible\nstructural reorganisation that opens up a pore network. The phenomenon is known\nto be highly dependent on topology, even if the nature of this dependence is\nnot well understood: certain ordered entanglements (`weavings') can swell to\nmany times their original volume while others are entirely incapable of\nswelling at all. Given this sensitivity to topology, it is puzzling how the\ndisordered entanglements of many real materials manage to support cooperative\ndilation mechanisms. Here we use a combination of geometric and\nlattice-dynamical modelling to study the effect of disorder on swelling\nbehaviour. The model system we devise spans a continuum of disordered\ntopologies and is bounded by ordered states whose swelling behaviour is already\nknown to be either vanishingly small or extreme. We find that while topological\ndisorder often quenches swelling behaviour, certain disordered states possess a\nsurprisingly large swelling capacity. Crucially, we show that the extreme\nswelling response previously observed only for certain specific weavings can be\nmatched---and even superseded---by that of disordered entanglements. Our\nresults establish a counterintuitive link between topological disorder and\nmechanical flexibility that has implications not only for polymer science but\nalso for our broader understanding of collective phenomena in disordered\nsystems.",
        "positive": "Property of Zero-Energy Flows and Creations and Annihilations of\n  Vortices in Quantum Mechanics: Time-dependent processes accompanied by vortex creations and annihilations\nare investigated in terms of the eigenstates in conjugate spaces of Gel'fand\ntriplets in 2-dimensions. Creations and annihilations of vortices are described\nby the insertions of unstable eigenstates with complex-energy eigenvalues into\nstable states written by the superposition of eigenstates with zero-energy\neigenvalues. Some concrete examples are presented in terms of the\neigenfunctions of the 2-dimensional parabolic potential barrier, i.e., $-m\n\\gamma^2 (x^2+y^2)/2$. We show that the processes accompanied by vortex\ncreations and annihilations can be analyzed in terms of the eigenfunctions in\nthe conjugate spaces of Gel'fand triplets. Throughout these examinations we\npoint out three interesting properties of the zero-energy flows. (i) Mechanisms\nusing the zero-energy flows are absolutely economical from the viewpoint of\nenergy consumption. (ii) An enormous amount of informations can be\ndiscriminated in terms of the infinite variety of the zero-energy flows. (iii)\nThe zero-energy flow patterns are absolutely stable in any disturbance by\ninserting arbitrary decaying flows with complex-energy eigenvalues."
    },
    {
        "anchor": "Collapse of Telechelic Star Polymers to Water-Melon Structures: Conformational properties of star-shaped polymer aggregates that carry\nattractive end-groups, called telechelic star polymers, are investigated by\nsimulation and analytical variational theory. We focus on the case of low\ntelechelic star polymer functionalities, $f \\leq 5$, a condition which allows\naggregation of all attractive monomers on one site. We establish the\nfunctionality- and polymerization-number dependence of the transition\ntemperature from the \"star burst'' to the \"water melon\" macroparticle\nstructure. Extensions to telechelic stars featuring partially collapsed\nconfigurations are also discussed.",
        "positive": "Quantitative analysis of non-equilibrium systems from short-time\n  experimental data: We provide a minimal strategy for the quantitative analysis of a large class\nof non-equilibrium systems in a {statistically} steady state using the\nshort-time Thermodynamic Uncertainty Relation (TUR). From short-time trajectory\ndata obtained from experiments, we demonstrate how we can simultaneously infer\nquantitatively, both the thermodynamic force field acting on the system, as\nwell as the (potentially exact) rate of entropy production. We benchmark this\nscheme first for an experimental study of a colloidal particle system where\nexact analytical results are known, before applying it to the case of a\ncolloidal particle in a hydrodynamical flow field, where neither analytical nor\nnumerical results are available. In this latter case, we build an effective\nmodel of the system based on our results. In both cases, we also demonstrate\nthat our results match with those obtained from another recently introduced\nscheme [Phys. Rev. X 10, 021009]."
    },
    {
        "anchor": "Electrification in granular gases leads to constrained fractal growth: The empirical observation of aggregation of dielectric particles under the\ninfluence of electrostatic forces lies at the origin of the theory of\nelectricity. The growth of clusters formed of small grains underpins a range of\nphenomena from the early stages of planetesimal formation to aerosols. However,\nthe collective effects of Coulomb forces on the nonequilibrium dynamics and\naggregation process in a granular gas -- a model representative of the above\nphysical processes -- have so far evaded theoretical scrutiny. Here, we\nestablish a hydrodynamic description of aggregating granular gases that\nexchange charges upon collisions and interact via the long-ranged Coulomb\nforces. We analytically derive the governing equations for the evolution of\ngranular temperature, charge variance, and number density for homogeneous and\nquasi-monodisperse aggregation. We find that, once the aggregates are formed,\nthe system obeys a physical constraint of nearly constant dimensionless ratio\nof characteristic electrostatic to kinetic energy $\\mathcal{B}(t)\\le 1$. This\nconstraint on the collective evolution of charged clusters is confirmed both by\nthe theory and the detailed molecular dynamics simulations. The inhomogeneous\naggregation of monomers and clusters in their mutual electrostatic field\nproceeds in a fractal manner. Our theoretical framework is extendable to more\nprecise charge exchange mechanism, a current focus of extensive\nexperimentation. Furthermore, it illustrates the collective role of long-ranged\ninteractions in dissipative gases and can lead to novel designing principles in\nparticulate systems.",
        "positive": "Spatial repartition of local plastic processes in different creep\n  regimes in a granular material: Granular packings under constant shear stress display below the Coulomb\nlimit, a logarithmic creep dynamics. However the addition of small stress\nmodulations induces a linear creep regime characterized by an effective viscous\nresponse. Using Diffusing Wave Spectroscopy, we investigate the relation\nbetween creep and local plastic events spatial distribution (\"hot-spots\")\ncontributing to the plastic yield. The study is done in the two regimes, i.e.\nwith and without mechanical activation. The hot-spot dynamics is related to the\nmaterial effective fluidity. We show that far from the threshold, a local\nvisco-elastic rheology coupled to an ageing of the fluidity parameter, is able\nto render the essential spatio-temporal features of the observed creep\ndynamics."
    },
    {
        "anchor": "Unexpected Universality in the Viscosity of Metallic Liquids: The range of the magnitude of the liquid viscosity as a function of the\ntemperature (T) is one of the most impressive of any physical property,\nchanging by approximately 17 orders of magnitude from its extrapolated value at\ninfinite temperature to that at the glass transition. We present experimental\nmeasurements of containerlessly processed metallic liquids that reveal that the\nratio of the viscosity to its extrapolated infinite temperature value follows a\nuniversal function of Tcoop/T. The temperature Tcoop corresponds to the onset\nof cooperative motion and is strongly correlated with the glass transition\ntemperature. On average the extrapolated infinite temperature viscosity is\nfound to be nh, where h is Planck's constant and n is the particle number\ndensity. A surprising universality in the viscosity of metallic liquids and its\nrelation to the glass transition is demonstrated.",
        "positive": "Packing and voids in electro-rheological structures of polarized clay\n  particles: Oil suspensions of fluorohectorite clay particles exhibit a dramatic\nmeso-structural ordering when submitted to a strong electric field. This is due\nto dipolar interaction between polarized fluorohectorite particles, which\norientate and aggregate to form chains and/or bundle-like structures along the\ndirection of the applied electric field. We have used synchrotron small angle\nX-ray scattering to get insight into the nature of the porous medium in the\nbundles. Three types of fluorohectorite clay samples corresponding to three\ndifferent intercalated cations Na+, Ni2+ and Fe3+ were studied. The\ntwo-dimensional SAXS images from bundles of fluorohectorites exhibit a marked\nanisotropy which is analyzed by fitting ellipses to iso-intensity lines of SAXS\npatterns. This also provides principal directions along which one-dimensional\nspectra are computed. They display a power law behavior typical of porous\nmedia, separated by crossovers. The crossovers are interpreted in terms of\ntypical length scales for the clay particle bundles, providing for the first\ntime a quantitative image of the 3D geometry inside such bundles of polarized\nclay particles. The exponents of the power laws indicate either predominant\nsurface- (for 2 types of samples) or bulk- (for the last type) scattering, at\nall length scales investigated."
    },
    {
        "anchor": "Shape deformation of a vesicle under axisymmetric non-uniform\n  alternating electric field: Non-uniform fields are commonly used to study vesicle dielectrophoresis and\ncan be used to hitherto relatively unexplored areas of vesicle deformation and\nelectroporation. A common but perplexing problem in vesicle dynamics is the\ncross over from the entropic to enthalpic (stretching) tension during vesicle\ndeformation. A lucid demonstration of this concept is provided by the study of\nvesicle deformation and dielectrophoresis under axisymmetric quadrupole\nelectric field. Small deformation theory incorporating the Maxwell stress\napproach is used (employing area and volume conservation constraints) to\nestimate the dielectrophoretic velocity. The entropic and enthalpic tensions\nare implemented to understand vesicle electrohydrodynamics in low and high\ntension limits. The shapes obtained using the entropic and the enthalpic\napproaches, show significant differences. A strong dependence of the final\nvesicle shapes on the ratio of electrical conductivities of the fluids inside\nand outside the vesicle as well as on the frequency of the applied quadrupole\nelectric field is observed which could be used to estimate electromechanical\nproperties of the vesicle. Moreover, an excess area dependent transition\nbetween the entropic and enthalpic regimes is observed. The Maxwell stress\napproach, used in this work, indicates that Clausius-Mossotti factor obtained\nby the dipole moment method together with the drag on a rigid sphere explains\nvesicle dielectrophoresis. Interestingly, the coupling of hydrodynamic and\nelectric stress, important in drops is absent in vesicle dielectrophoresis to\nlinear order.",
        "positive": "Scattering functions of knotted ring polymers: We discuss the scattering function of a Gaussian random polygon with N nodes\nunder a given topological constraint through simulation. We obtain the Kratky\nplot of a Gaussian polygon of N=200 having a fixed knot for some different\nknots such as the trivial, trefoil and figure-eight knots. We find that some\ncharacteristic properties of the different Kratky plots are consistent with the\ndistinct values of the mean square radius of gyration for Gaussian polygons\nwith the different knots."
    },
    {
        "anchor": "Different Scenarios for Critical Glassy Dynamics: We study the role of different terms in the $N$-body potential of glass\nforming systems on the critical dynamics near the glass transition. Using a\nsimplified spin model with quenched disorder, where the different terms of the\nreal $N$-body potential are mapped into multi-spin interactions, we identified\nthree possible scenarios. For each scenario we introduce a ``minimal'' model\nrepresentative of the critical glassy dynamics near, both above and below, the\ncritical transition lin e. For each ``minimal'' model we discuss the low\ntemperature equilibrium dynamics.",
        "positive": "Orientational ordering of confined hard rods: the effect of shape\n  anisotropy on surface ordering and capillary nematization: We examine the ordering properties of rectangular hard rods with length L and\ndiameter D at a single planar wall and between two parallel hard walls using\nthe second-virial density functional theory. The theory is implemented in the\nthree-state Zwanzig approximation, where only three mutually perpendicular\ndirections are allowed for the orientations of hard rods. The effect of varying\nshape anisotropy is examined at L/D=10, 15 and 20. In contact with a single\nhard wall, the density profiles show planar ordering, damped oscillatory\nbehavior, and wall induced surface ordering transition below the coexisting\nisotropic density of bulk isotropic-nematic (I-N) phase transition. Upon\napproaching the coexisting isotropic density, the thickness of nematic film\ndiverges logarithmically, i.e. the nematic wetting is complete for any shape\nanisotropy. In the case of confinement between two parallel hard walls, it is\nfound that the continuous surface ordering transition depends strongly on the\ndistance between confining walls (H) for H<L, while it depends weakly on H for\nH>L. The minimal density at which a surface ordering transition can be realized\nis located at around H~2D for all studied shape anisotropies due to the strong\ninterference effect between the two hard walls. The first order I-N phase\ntransition of the bulk system becomes surface ordered isotropic (IB)-capillary\nnematic (NB) phase transition in the slit pore. This first order IB-NB\ntransition weakens with decreasing pore width and terminates in a critical\npoint for all studied shape anisotropies."
    },
    {
        "anchor": "Spatiotemporal control of active topological defects: Topological defects play a central role in the physics of many materials,\nincluding magnets, superconductors and liquid crystals. In active fluids,\ndefects become autonomous particles that spontaneously propel from internal\nactive stresses and drive chaotic flows stirring the fluid. The intimate\nconnection between defect textures and active flow suggests that properties of\nactive materials can be engineered by controlling defects, but design\nprinciples for their spatiotemporal control remain elusive. Here we provide a\nsymmetry-based additive strategy for using elementary activity patterns, as\nactive topological tweezers, to create, move and braid such defects. By\ncombining theory and simulations, we demonstrate how, at the collective level,\nspatial activity gradients act like electric fields which, when strong enough,\ninduce an inverted topological polarization of defects, akin to an exotic\nnegative susceptibility dielectric. We harness this feature in a dynamic\nsetting to collectively pattern and transport interacting active defects. Our\nwork establishes an additive framework to sculpt flows and manipulate active\ndefects in both space and time, paving the way to design programmable active\nand living materials for transport, memory and logic.",
        "positive": "The Lennard-Jones-Devonshire cell model revisited: We reanalyse the cell theory of Lennard-Jones and Devonshire and find that in\naddition to the critical point originally reported for the 12-6 potential (and\nwidely quoted in standard textbooks), the model exhibits a further critical\npoint. We show that the latter is actually a more appropriate candidate for\nliquid-gas criticality than the original critical point."
    },
    {
        "anchor": "A macroscopic model for sessile droplet evaporation on a flat surface: The evaporation of sessile droplets on a flat surface involves a complex\ninterplay between phase change, diffusion, advection and surface forces. In an\nattempt to significantly reduce the complexity of the problem and to make it\nmanageable, we propose a simple model hinged on a surface free energy-based\nrelaxation dynamics of the droplet shape, a diffusive evaporation model and a\ncontact line pinning mechanism governed by a yield stress. Our model reproduces\nthe known dynamics of droplet shape relaxation and of droplet evaporation, both\nin the absence and in the presence of contact line pinning. We show that shape\nrelaxation during evaporation significantly affects the lifetime of a drop. We\nfind that the dependence of the evaporation time on the initial contact angle\nis a function of the competition between the shape relaxation and evaporation,\nand is strongly affected by any contact line pinning.",
        "positive": "Spinodal-assisted crystallization in polymer melts: Recent experiments in some polymer melts quenched below the melting\ntemperature have reported spinodal kinetics in small-angle X ray scattering\nbefore the emergence of crystalline structure. To explain these observations we\npropose that the coupling between density and chain conformation induces a\nliquid-liquid binodal within the equilibrium liquid--crystalline solid\ncoexistence region. A simple phenomenological theory is developed to illustrate\nthis idea, and several experimentally testable consequences are discussed.\nShear is shown to enhance the kinetic role of the hidden binodal."
    },
    {
        "anchor": "On the existence of a second branch of transverse collective excitations\n  in liquid metals: It was found recently that the liquid dynamics of several metals (Li, Zn, Ni,\nFe, Tl, Pb) under pressure is characterized by transverse spectral functions\ncontaining an additional high-frequency peak. To rationalize the pressure\ndependence of the contributions from different propagating processes to\ntransverse spectral functions in liquid metals, ab initio molecular dynamics\nsimulations were performed for two typical liquid metals (Na and Al) in a wide\nrange of pressures. The influence of density/pressure is investigated for Na by\nconsidering four pressures ranging from 15 to 147 GPa, while the temperature\ninfluence is considered for Al between 600 K in the deep supercooled liquid up\nto 1700 K well above the melting point at ambient pressure. Both temperature\nand density dependence of the spectra of collective excitations are analyzed\nwith a focus on the appearance of a second high-frequency mode in the\ntransverse spectra. A correspondence between spectra of transverse collective\nexcitations and the peak positions of the Fourier-spectra of velocity\nautocorrelation functions (vibrational density of states) is found.",
        "positive": "Liquid-crystal enabled electrophoresis: Scenarios for driving and\n  reconfigurable assembling of colloids: We demonstrate several examples of driving and steering of colloids when\ndispersed in nematic liquid crystals. The driving mechanism is based on the\nprinciple of nonlinear electrophoresis which is mediated by the asymmetry in\nthe structure of the defects that the inclusions generate in the host elastic\nmatrix. The steering mechanism originates in the photoactivation of the\nanchoring conditions of the nematic liquid crystal on one of the enclosing\nplates. As experimental realizations we first review a scenario of water\nmicrodroplets being phoretically transported for cargo release and chemical\nreaction. Steering is illustrated in terms of the reconfigurable assembly of\ncolloidal particles, either in the form of asters or rotating-mills, commanded\nby predesigned patterns of illumination."
    },
    {
        "anchor": "Universal scaling for disordered viscoelastic matter II: Collapses,\n  global behavior and spatio-temporal properties: Disordered viscoelastic materials are ubiquitous and exhibit fascinating\ninvariant scaling properties. In a companion article, we have presented\ncomprehensive new results for the critical behavior of the dynamic\nsusceptibility of disordered elastic systems near the onset of rigidity. Here\nwe provide additional details of the derivation of the singular scaling forms\nof the longitudinal response near both jamming and rigidity percolation. We\nthen discuss global aspects associated with these forms, and make scaling\ncollapse plots for both undamped and overdamped dynamics in both the rigid and\nfloppy phases. We also derive critical exponents, invariant scaling\ncombinations and analytical formulas for universal scaling functions of several\nquantities such as transverse and density responses, elastic moduli,\nviscosities, and correlation functions. Finally, we discuss tentative\nexperimental protocols to measure these behaviors in colloidal suspensions.",
        "positive": "Effective potentials between gold nano crystals -- functional dependence\n  on the temperature: A method is presented that allows to combine the effective potential between\ntwo nano crystals, the potential of mean force (PMF), as obtained from\nall-atomistic Molecular Dynamics simulations with perturbation theory. In this\nway, a functional dependence of the PMF on temperature is derived, that enables\nthe prediction of the PMF in a wide temperature range. We applied the method\nfor systems of capped gold nano crystals of different size. They show very good\nagreement with data from atomistic simulations."
    },
    {
        "anchor": "Electro- and photoswitching of undulation structures in planar\n  cholesteric layers aligned by a polyimide film possessing various values of\n  the anchoring energy: The base for this manuscript was laid down by the studies carried out in the\narticle by Senyuk B, et. al. Proceedings of SPIE. 2005; 5936: 59360W-1-9. In\nthe present manuscript, a planar layer of the photosensitive cholesteric, based\non the chiral dopant 2-(4'-phenylbenzylidene)-p-menthane-3-one dissolved in the\nnematic E7, under the alternating electric field was explored. In particular,\nthe influence of UV exposure and the value of the azimuthal anchoring energy on\nelectro- and photoswitching of undulation instabilities was considered. Due to\nthe decrease in a ratio between the LC cell thickness d and the cholesteric\nhelical pitch P, different types of undulations, observed under the electrical\nfield, were switched by UV exposure. The change in the ratio d/P was realized\nowing to the unwinding of the photosensitive cholesteric helix during UV\nexposure in the LC cell with a fixed thickness d. Sequential transitions of\ntypes of the undulations from 2D to two 1D structures (1D|| and 1D_) were\nachieved. The undulation structure 1D|| with a controlled period of a grating\nin electric field was examined. Dependencies of jumps of the period and the\ndiffraction efficiency of a photosensitive cholesteric grating on the anchoring\nenergy of alignment layers were analyzed.",
        "positive": "Microscopically-resolved simulations prove the existence of soft cluster\n  crystals: We perform extensive monomer-resolved computer simulations of\nsuitably-designed amphiphilic dendritic macromolecules over a broad range of\ndensities, proving the existence and stability of cluster crystals formed in\nthese systems, as predicted previously on the basis of effective pair\npotentials [B. M. Mladek et al., Phys. Rev. Lett. 96, 045701 (2006)]. Key\nproperties of these crystals, such as the adjustment of their site occupancy\nwith density and the possibility to heal defects by dendrimer migration, are\nconfirmed on the monomer-resolved picture. At the same time, important\ndifferences from the predictions of the pair potential picture, stemming from\nsteric crowding, arise as well and they place an upper limit in the density for\nwhich such crystals can exist."
    },
    {
        "anchor": "Monomer-resolved simulations of cluster-forming dendrimers: We present results of monomer-resolved Monte Carlo simulations for a system\nof amphiphilic dendrimers of second generation. Our investigations validate a\ncoarse-grained level description based on the zero-density limit effective\npair-interactions for low and intermediate densities, which predicted the\nformation of stable, finite aggregates in the fluid phase. Indeed, we find that\nthese systems form a homogeneous fluid for low densities, which on increasing\nthe density spontaneously transforms into a fluid of clusters of dendrimers.\nAlthough these clusters are roughly spherical in nature for intermediate\ndensities, also more complex structures are detected for the highest densities\nconsidered.",
        "positive": "Mobile Localization in nonlinear Schrodinger lattices: Using continuation methods from the integrable Ablowitz-Ladik lattice, we\nhave studied the structure of numerically exact mobile discrete breathers in\nthe standard Discrete Nonlinear Schrodinger equation. We show that, away from\nthat integrable limit, the mobile pulse is dressed by a background of resonant\nplane waves with wavevectors given by a certain selection rule. This background\nis seen to be essential for supporting mobile localization in the absence of\nintegrability. We show how the variations of the localized pulse energy during\nits motion are balanced by the interaction with this background, allowing the\nlocalization mobility along the lattice."
    },
    {
        "anchor": "Dielectric properties of aqueous electrolytes at the nanoscale: Despite the ubiquity of nanoconfined aqueous electrolytes, a theoretical\nframework that accounts for the nonlinear coupling of water and ion\npolarization is still missing. We introduce a nonlocal and nonlinear field\ntheory for the nanoscale polarization of ions and water and derive the\nelectrolyte dielectric properties as a function of salt concentration to first\norder in a loop expansion. Classical molecular dynamics simulations are\nfavorably compared with the calculated dielectric response functions. The\ntheory correctly predicts the dielectric permittivity decrement with rising\nsalt concentration and furthermore shows that salt induces a Debye screening in\nthe longitudinal susceptibility but leaves the short-range water organization\nremarkably unchanged.",
        "positive": "Microscale characterisation of the time-dependent mechanical behaviour\n  of brain white matter: Brain mechanics is a topic of deep interest because of the significant role\nof mechanical cues in both brain function and form. Specifically, capturing the\nheterogeneous and anisotropic behaviour of cerebral white matter (WM) is\nextremely challenging and yet the data on WM at a spatial resolution relevant\nto tissue components are sparse. To investigate the time-dependent mechanical\nbehaviour of WM, and its dependence on local microstructural features when\nsubjected to small deformations, we conducted atomic force microscopy (AFM)\nstress relaxation experiments on corpus callosum (CC), corona radiata (CR) and\nfornix (FO) of fresh ovine brain. Our experimental results show a dependency of\nthe tissue mechanical response on axons orientation, with e.g. the stiffness of\nperpendicular and parallel samples is different in all three regions of WM\nwhereas the relaxation behaviour is different for the CC and FO regions. An\ninverse modelling approach was adopted to extract Prony series parameters of\nthe tissue components, i.e. axons and extra cellular matrix with its accessory\ncells, from experimental data. Using a bottom-up approach, we developed\nanalytical and FEA estimates that are in good agreement with our experimental\nresults. Our systematic characterisation of sheep brain WM using a combination\nof AFM experiments and micromechanical models provide a significant\ncontribution for predicting localised time-dependent mechanics of brain tissue.\nThis information can lead to more accurate computational simulations, therefore\naiding the development of surgical robotic solutions for drug delivery and\naccurate tissue mimics, as well as the determination of criteria for tissue\ninjury and predict brain development and disease progression."
    },
    {
        "anchor": "Anisotropic Heisenberg model for the mixed spin-3/2 and spin-1/2 under\n  random crystal field: Thermodynamic properties of the mixed spin-3/2 and spin-1/2 Heisenberg model\nare examined within the Oguchi approximation in the presence of a random\ncrystal-field (RCF). The RCF is either introduced with probability p or turned\noff with probability 1-p randomly. The thermal variations of the global\nmagnetization and free energy of the system are investigated to construct the\nphase diagrams for the classical, quantum and anisotropic cases. Different\nresults revealed that no qualitative changes exist between them. Quantum\neffects are found to be present and abundant in the quantum model in the\nnegative D -range. This phenomenon has a strong decreasing effect on the\ncritical temperature which becomes much lower than in the classical case. In\nthe presence of an external field, it was observed that coercivity and\nremanence decrease in a wide range of the absolute temperature.",
        "positive": "Physical origin of shear-banding in jammed systems: Jammed systems all have a yield stress. Among these materials some have been\nshown to shear-band but it is as yet unclear why some materials develop\nshear-band and some others do not. In order to rationalize existing data\nconcerning the flow characteristics of jammed systems and in particular\nunderstand the physical origin of such a difference we propose a simple\napproach for describing the steady flow behaviour of yield stress fluids, which\nretains only basic physical ingredients. Within this frame we show that in the\nliquid regime the behaviour of jammed systems turns from that of a simple yield\nstress fluid (exhibiting homogeneous flows) to a shear-banding material when\nthe ratio of a characteristic relaxation time of the system to a restructuring\ntime becomes smaller than 1, thus suggesting a possible physical origin of\nthese trends."
    },
    {
        "anchor": "Edwards Statistical Mechanics for Jammed Granular Matter: In 1989, Sir Sam Edwards made the visionary proposition to treat jammed\ngranular materials using a volume ensemble of equiprobable jammed states in\nanalogy to thermal equilibrium statistical mechanics, despite their inherent\nathermal features. Since then, the statistical mechanics approach for jammed\nmatter has garnered an extraordinary amount of attention by both theorists and\nexperimentalists. Here, we review a systematic approach to jammed matter based\non the Edwards statistical mechanical ensemble. We discuss the construction of\nmicrocanonical and canonical ensembles based on the volume function, which\nreplaces the Hamiltonian in jammed systems. The importance of approximation\nschemes at various levels is emphasized leading to quantitative predictions for\nensemble averaged quantities such as packing fractions and contact force\ndistributions. An overview of the phenomenology of jammed states and\nexperiments, simulations, and theoretical models scrutinizing the strong\nassumptions underlying Edwards' approach is given including recent results\nsuggesting the validity of Edwards ergodic hypothesis for jammed states. A\ntheoretical framework for packings whose constitutive particles range from\nspherical to non-spherical shapes like dimers, polymers, ellipsoids,\nspherocylinders or tetrahedra, hard and soft, frictional, frictionless and\nadhesive, monodisperse and polydisperse particles in any dimensions is\ndiscussed providing insight into an unifying phase diagram for all jammed\nmatter. Furthermore, the connection between the Edwards' ensemble of metastable\njammed states and metastability in spin-glasses is established. This highlights\nthat the packing problem can be understood as a constraint satisfaction problem\nfor excluded volume and force and torque balance leading to a unifying\nframework between the Edwards ensemble of equiprobable jammed states and\nout-of-equilibrium spin-glasses.",
        "positive": "Multiscale approach to equilibrating model polymer melts: We present an effective and simple multiscale method for equilibrating Kremer\nGrest model polymer melts of varying stiffness. In our approach, we\nprogressively equilibrate the melt structure above the tube scale, inside the\ntube and finally at the monomeric scale. We make use of models designed to be\ncomputationally effective at each scale. Density fluctuations in the melt\nstructure above the tube scale are minimized through a Monte Carlo simulated\nannealing of a lattice polymer model. Subsequently the melt structure below the\ntube scale is equilibrated via the Rouse dynamics of a force-capped\nKremer-Grest model that allows chains to partially interpenetrate. Finally the\nKremer-Grest force field is introduced to freeze the topological state and\nenforce correct monomer packing. We generate $15$ melts of $500$ chains of\n$10.000$ beads for varying chain stiffness as well as a number of melts with\n$1.000$ chains of $15.000$ monomers. To validate the equilibration process we\nstudy the time evolution of bulk, collective and single-chain observables at\nthe monomeric, mesoscopic and macroscopic length scales. Extension of the\npresent method to longer, branched or polydisperse chains and/or larger system\nsizes is straight forward."
    },
    {
        "anchor": "Complex oscillatory yielding of model hard sphere glasses: The yielding behaviour of hard sphere glasses under large amplitude\noscillatory shear has been studied by probing the interplay of Brownian motion\nand shear-induced diffusion at varying oscillation frequencies. Stress,\nstructure and dynamics are followed by experimental rheology and Browian\nDynamics simulations. Brownian motion assisted cage escape dominates at low\nfrequencies while escape through shear-induced collisions at high ones, both\nrelated with a yielding peak in\\ $G^{\\prime \\prime}$. At intermediate\nfrequencies a novel, for HS glasses, double peak in $G^{\\prime \\prime}$ is\nrevealed reflecting both mechanisms. At high frequencies and strain amplitudes\na persistent structural anisotropy causes a stress drop within the cycle after\nstrain reversal, while higher stress harmonics are minimized at certain strain\namplitudes indicating an apparent harmonic response.",
        "positive": "Single chain elasticity and thermoelasticity of polyethylene: Single-chain elasticity of polyethylene at $\\theta$ point up to 90% of\nstretching with respect to its contour length is computed by Monte-Carlo\nsimulation of an atomistic model in continuous space. The elasticity law\ntogether with the free-energy and the internal energy variations with\nstretching are found to be very well represented by the wormlike chain model up\nto 65% of the chain elongation, provided the persistence length is treated as a\ntemperature dependent parameter. Beyond this value of elongation simple ideal\nchain models are not able to describe the Monte Carlo data in a thermodynamic\nconsistent way. This study reinforces the use of the wormlike chain model to\ninterpret experimental data on the elasticity of synthetic polymers in the\nfinite extensibility regime, provided the chain is not yet in its fully\nstretched regime. Specific solvent effects on the elasticity law and the\npartition between energetic and entropic contributions to single chain\nelasticity are investigated."
    },
    {
        "anchor": "Solitary wave trains in granular chains: Experiments, theory and\n  simulations: The features of solitary waves observed in horizontal monodisperse chain of\nbarely touching beads not only depend on geometrical and material properties of\nthe beads but also on the initial perturbation provided at the edge of the\nchain. An impact of a large striker on a monodisperse chain, and similarly a\nsharp decrease of bead radius in a stepped chain, generates a solitary wave\ntrain containing many single solitary waves ordered by decreasing amplitudes.\nWe find, by simple analytical arguments, that the unloading of compression\nforce at the chain edge has a nearly exponential decrease. The characteristic\ntime is mainly a function involving the grains' masses and the striker mass.\nNumerical calculations and experiments corroborate these findings.",
        "positive": "Hydrodynamic effects in the capture of rod-like molecules by a nanopore: In the approach of biomolecules to a nanopore, it is essential to capture the\neffects of hydrodynamic anisotropy of the molecules and the near-wall\nhydrodynamic interactions which hinder their diffusion. We present a detailed\ntheoretical analysis of the behaviour of a rod-like molecule attracted\nelectrostatically by a charged nanopore. We first estimate the time scales\ncorresponding to Brownian and electrostatic translations and reorientation. We\nfind that Brownian motion becomes negligible at distances within the pore\ncapture radius, and numerically determine the trajectories of the nano-rod in\nthis region to explore the effects of anisotropic mobility. This allows us to\ndetermine the range of directions from the pore in which hydrodynamic\ninteractions with the boundary shape the approach dynamics and need to be\naccounted for in detailed modelling."
    },
    {
        "anchor": "Cutting and tearing thin elastic sheets: two novel single-period cracks\n  and the first period-doubling crack: Two novel single-period cracks were observed in experiments of cutting a\nfolded sheet with a blunt object and tearing a thin brittle sheet under the\nguidance of a meterstick. Additionally, we observed a period-doubling crack in\nthe tearing experiment. We cut and tore the sheet in different directions. The\nexperimental results suggested that the anisotropy of the thin sheet played an\nimportant role in the formation of these two types of saw-tooth cracks. We\ndemonstrated that the formation of the period-doubling crack was closely\ncorrelated with the changing of the contact region between the sheet and the\nmeterstick. We also showed that the growth process of crack made by cutting was\na logistic growth process (S-curve), while the cracks made by tearing\npropagated in the form of approximate power-law function.",
        "positive": "A Simplest Swimmer at Low Reynolds Number: Three Linked Spheres: We propose a very simple one-dimensional swimmer consisting of three spheres\nthat are linked by rigid rods whose lengths can change between two values. With\na periodic motion in a non-reciprocal fashion, which breaks the time-reversal\nsymmetry as well as the translational symmetry, we show that the model device\ncan swim at low Reynolds number. This model system could be used in\nconstructing molecular-size machines."
    },
    {
        "anchor": "Force Dependent Hopping Rates of RNA Hairpins can be Estimated from\n  Accurate Measurement of the Folding Landscapes: The sequence-dependent folding landscapes of nucleic acid hairpins reflect\nmuch of the complexity of biomolecular folding. Folding trajectories, generated\nusing single molecule force clamp experiments by attaching semiflexible\npolymers to the ends of hairpins have been used to infer their folding\nlandscapes. Using simulations and theory, we study the effect of the dynamics\nof the attached handles on the handle-free RNA free energy profile\n$F^o_{eq}(z_m)$, where $z_m$ is the molecular extension of the hairpin.\nAccurate measurements of $F^o_{eq}(z_m)$ requires stiff polymers with small\n$L/l_p$, where $L$ is the contour length of the handle, and $l_p$ is the\npersistence length. Paradoxically, reliable estimates of the hopping rates can\nonly be made using flexible handles. Nevertheless, we show that the equilibrium\nfree energy profile $F^o_{eq}(z_m)$ at an external tension $f_m$, the force\n($f$) at which the folded and unfolded states are equally populated, in\nconjunction with Kramers' theory, can provide accurate estimates of the\nforce-dependent hopping rates in the absence of handles at arbitrary values of\n$f$. Our theoretical framework shows that $z_m$ is a good reaction coordinate\nfor nucleic acid hairpins under tension.",
        "positive": "pi-Conjugation and conformation in a semiconducting polymer: small angle\n  x-ray scattering study: Small angle X-ray scattering (SAXS) in\npoly[2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) solution\nhas shown the important role of pi-electron conjugation in controlling the\nchain conformation and assembly. By increasing the extent of conjugation from\n30 to 100 %, the persistence length (l_p) increases from 20 to 66 Angstrom.\nMoreover, a pronounced second peak in the pair distribution function has been\nobserved in fully conjugated chain, at larger length scales. This feature\nindicates that the chain segments tend to self-assemble as the conjugation\nalong the chain increases. Xylene enhances the rigidity of PPV backbone to\nyield extended structures, while tetrahydrofuran solvates the side groups to\nform compact coils in which the l_p is much shorter."
    },
    {
        "anchor": "Slow dynamic elastic recovery in unconsolidated metal structures: Slow dynamic nonlinearity is widely observed in brittle materials with\ncomplex heterogeneous or cracked microstructures. It is seen in rocks, concrete\nand cracked glass blocks. Unconsolidated structures show the behavior as well:\naggregates of glass beads under pressure and a single glass bead confined\nbetween two glass plates. A defining feature is the loss of stiffness after a\nmechanical conditioning, followed by a logarithmic-in-time recovery. Materials\nobserved to exhibit slow dynamics are sufficiently different in microstructure,\nchemical composition, and scale (ranging from the laboratory to the\nseismological) to suggest some kind of universality. There lacks a full\ntheoretical understanding of the universality in general and the log(time)\nrecovery in particular; one suspicion has been that the phenomenon is\nassociated with glassy grain boundaries and microcracking. Seminal studies were\nfocused on sandstones and other natural rocks, but in recent years other\nexperimental venues have been introduced with which to inform theory. Here, we\npresent measurements on some simple metallic systems: an unconsolidated\naggregate of aluminum beads under a confining pressure, and an aluminum bead\nconfined between two aluminum plates, and a steel bead confined between steel\nplates. Ultrasonic waves are used as probes of the systems, and changes are\nassessed with coda wave interferometry. Three different methods of\nlow-frequency conditioning are applied; all reveal slow dynamic nonlinearities.\nResults imply that glassy microstructures and cracking do not play essential\nroles, as they would appear to be absent in our systems.",
        "positive": "Capture and translocation of a rod-like molecule by a nanopore:\n  orientation, charge distribution and hydrodynamics: We investigate the translocation of rods with different charge distributions\nusing hybrid Langevin Dynamics and Lattice Boltzmann (LD-LB) simulations.\nElectrostatic interactions are added to the system using the $P^3M$ algorithm\nto model the electrohydrodynamic interactions (EHI). We first examine the\nfree-solution electrophoretic properties of rods with various charge\ndistributions. Our translocation simulation results suggest that the order\nparameter is asymmetric during the capture and escape processes despite the\nsymmetric electric field lines, while the impacts of the charge distribution on\nrod orientation are more significant during the capture process. The\ncapture/threading/escape times are under the combined effects of charge\nscreening, rod orientation, and charge distributions. We also show that the\nmean capture time of a rod is shorter when it is launched near the wall because\nrods tend to align along the wall and hence with the local field lines.\nRemarkably, the \\textit{orientational capture radius} we proposed previously\nfor uniformly charged rods is still valid in the presence of EHI."
    },
    {
        "anchor": "Particle-scale modeling of the drying characteristics of colloidal\n  suspensions: During drying of colloidal suspensions, colloidal particles can form\nconcentrated particle layers beneath the receding free surface. The drying rate\ncan gradually decrease with the growth of the particle layers. We construct a\nmodel to investigate how such drying characteristics is affected by\ninteractions between particles. In this model, the formation of the particle\nlayers is described by Langevin dynamics simulations, and the drying rate is\nevaluated from the permeation resistance of the particle layers. We show that\nthe decrease in the drying rate is suppressed when the particles form\naggregates by attractive interactions. The present model would enable us to\npredict and control the drying characteristics through the character of\ncolloidal particles.",
        "positive": "Transition between globule and stretch states of a self-attracting chain\n  in the repulsive active particle bath: Folding and unfolding of biopolymers are often manipulated in experiment by\ntuning pH, temperature, single-molecule force or shear field. Here we carry out\nBrownian dynamics simulations to explore the behavior of a single\nself-attracting chain in the suspension of self-propelling particles (SPPs). As\nthe propelling force increases, globule-stretch (G-S) transition of the chain\nhappens due to the enhanced disturbance from SPPs. Two distinct mechanisms of\nthe transition in the limits of low and high rotational diffusion rates of SPPs\nhave been observed: shear effect at low rate and collision-induced melting at\nhigh rate. The G-S and S-G (stretch-globule) curves form hysteresis loop at low\nrate, while they merge at high rate. Besides, we find two competing effects\nresult in the non-monotonic dependence of the G-S transition on the SPP density\nat low rate. Our results suggest an alternative approach to manipulating the\nfolding and unfolding of (bio)polymers by utilizing active agents."
    },
    {
        "anchor": "Non-inertial lateral migration of vesicles in bounded Poiseuille flow: Cross-streamline non-inertial migration of a vesicle in a bounded Poiseuille\nflow is investigated experimentally and numerically. The combined effects of\nthe walls and of the curvature of the velocity profile induce a movement\ntowards the center of the channel. A migration law (as a function of relevant\nstructural and flow parameters) is proposed that is consistent with\nexperimental and numerical results. This similarity law markedly differs from\nits analogue in unbounded geometry. The dependency on the reduced volume $\\nu$\nand viscosity ratio $\\lambda$ is also discussed. In particular, the migration\nvelocity becomes non monotonous as a function of $\\nu$ beyond a certain\n$\\lambda$.",
        "positive": "Shape Transitions in Network Model of Active Elastic Shells: Morphogenesis involves the transformation of initially simple shapes, such as\nmulticellular spheroids, into more complex $3D$ shapes. These shape changes are\ngoverned by mechanical forces including molecular motor-generated forces as\nwell as hydrostatic fluid pressure, both of which are actively regulated in\nliving matter through mechano-chemical feedback. Inspired by autonomous,\nbiophysical shape change, such as occurring in the model organism hydra, we\nintroduce a minimal, active, elastic model featuring a network of springs in a\nglobe-like spherical shell geometry. In this model there is coupling between\nactivity and the shape of the shell: if the local curvature of a filament\nrepresented by a spring falls below a critical value, its elastic constant is\nactively changed. This results in deformation of the springs that changes the\nshape of the shell. By combining excitation of springs and pressure regulation,\nwe show that the shell undergoes a transition from spheroidal to either\nelongated ellipsoidal or a different spheroidal shape, depending on pressure.\nThere exists a critical pressure at which there is an abrupt change from\nellipsoids to spheroids, showing that pressure is potentially a sensitive\nswitch for material shape. More complex shapes, involving loss of cylindrical\nsymmetry, can arise when springs are excited both above (spring constants\nincrease) and below (spring constants decrease) the curvature threshold. We\nthus offer biologically inspired design principles for autonomous shape\ntransitions in active elastic shells."
    },
    {
        "anchor": "Clustering of chemically propelled nanomotors in chemically active\n  environments: Synthetic nanomotors powered by chemical reactions have been designed to act\nas vehicles for active cargo transport, drug delivery as well as a variety of\nother uses. Collections of such motors, acting in consort, can self-assemble to\nform swarms or clusters, providing opportunities for applications on various\nlength scales. While such collective behavior has been studied when the motors\nmove in a chemically inactive fluid environment, when the medium in which they\nmove is a chemical network that supports complex spatial and temporal patterns,\nthrough simulation and theoretical analysis we show that collective behavior\nchanges. Spatial patterns in the environment can guide and control motor\ncollective states, and interactions of the motors with their environment can\ngive rise to distinctive spatiotemporal motor patterns. The results are\nillustrated by studies of the motor dynamics in systems that support Turing\npatterns and spiral waves. This work is relevant for potential applications\nthat involve many active nanomotors moving in complex chemical or biological\nenvironments.",
        "positive": "Depletion effects in smectic phases of hard rod--hard sphere mixtures: It is known that when hard spheres are added to a pure system of hard rods\nthe stability of the smectic phase may be greatly enhanced, and that this\neffect can be rationalised in terms of depletion forces. In the present paper\nwe first study the effect of orientational order on depletion forces in this\nparticular binary system, comparing our results with those obtained adopting\nthe usual approximation of considering the rods parallel and their orientations\nfrozen. We consider mixtures with rods of different aspect ratios and spheres\nof different diameters, and we treat them within Onsager theory. Our results\nindicate that depletion effects, and consequently smectic stability, decrease\nsignificantly as a result of orientational disorder in the smectic phase when\ncompared with corresponding data based on the frozen--orientation\napproximation. These results are discussed in terms of the $\\tau$ parameter,\nwhich has been proposed as a convenient measure of depletion strength. We\npresent closed expressions for $\\tau$, and show that it is intimately connected\nwith the depletion potential. We then analyse the effect of particle geometry\nby comparing results pertaining to systems of parallel rods of different shapes\n(spherocylinders, cylinders and parallelepipeds). We finally provide results\nbased on the Zwanzig approximation of a Fundamental--Measure\ndensity--functional theory applied to mixtures of parallelepipeds and cubes of\ndifferent sizes. In this case, we show that the $\\tau$ parameter exhibits a\nlinear asymptotic behaviour in the limit of large values of the hard--rod\naspect ratio, in conformity with Onsager theory, as well as in the limit of\nlarge values of the ratio of rod breadth to cube side length, $d$, in contrast\nto Onsager approximation, which predicts $\\tau\\sim d^3$."
    },
    {
        "anchor": "Local Rotational Jamming and Multi-Scale Hyperuniformities in an Active\n  Spinner System: An active system consisting of many self-spinning dimers is simulated, and a\ndistinct local rotational jamming transition is observed as the density\nincreases. In the low density regime, the system stays in an absorbing state,\nin which each dimer rotates independently subject to the applied torque. While\nin the high density regime, a fraction of the dimers become rotationally jammed\ninto local clusters, and the system exhibits spinodal-decomposition like\ntwo-phase morphologies. For high enough densities, the system becomes\ncompletely jammed in both rotational and translational degrees of freedom. Such\na simple system is found to exhibit rich and multiscale disordered\nhyperuniformities among the above phases: the absorbing state shows a critical\nhyperuniformity of the strongest class and subcritically preserves the\nvanishing density-fluctuation scaling up to some length scale; the\nlocally-jammed state shows a two-phase hyperuniformity conversely beyond some\nlength scale with respect to the phase cluster sizes; the totally jammed state\nappears to be a monomer crystal, but intrinsically loses large-scale\nhyperuniformity. These results are inspiring for designing novel\nphase-separation and disordered hyperuniform systems through dynamical\norganization.",
        "positive": "Guest-Tunable Dielectric Sensing Using a Single Crystal of HKUST-1: There is rising interest on low-k dielectric materials based on porous\nmetal-organic frameworks (MOFs) for improved electrical insulation in\nmicroelectronics. Herein, we demonstrate the concept of MOF dielectric sensor\nbuilt from a single crystal of HKUST-1. We study guest encapsulation effects of\npolar and non-polar molecules, by monitoring the transient dielectric response\nand AC conductivity of the crystal exposed to different vapors (water, I2,\nmethanol, ethanol). The dielectric properties were measured along the <100>\ncrystal direction in the frequency range of 100 Hz to 2 MHz. The dielectric\ndata show the efficacy of MOF dielectric sensor for discriminating the guest\nanalytes. The time-dependent transient response reveals dynamics of the\nmolecular inclusion and exclusion processes in the nanoscale pores. Since\ndielectric response is ubiquitous to all MOF materials (unlike DC conductivity\nand fluorescence), our results demonstrate the potential of dielectric MOF\nsensors compared to resistive sensors and luminescence-based approaches."
    },
    {
        "anchor": "Simulating dynamics of ellipsoidal particles using lattice Boltzmann\n  method: Anisotropic particles are often encountered in different fields of soft\nmatter and complex fluids. In this work, we present an implementation of the\ncoupled hydrodynamics of solid ellipsoidal particles and the surrounding fluid\nusing the lattice Boltzmann method. A standard link-based mechanism is used to\nimplement the solid-fluid boundary conditions. We develop an implicit method to\nupdate the position and orientation of the ellipsoid. This exploits the\nrelations between the quaternion which describes the ellipsoid's orientation\nand the ellipsoid's angular velocity to obtain a stable and robust dynamic\nupdate. The proposed algorithm is validated by looking at four scenarios: (i)\nthe steady translational velocity of a spheroid subject to an external force in\ndifferent orientations, (ii) the drift of an inclined spheroid subject to an\nimposed force, (iii) three-dimensional rotational motions in a simple shear\nflow (Jeffrey's orbits), and (iv) developed fluid flows and self-propulsion\nexhibited by a spheroidal microswimmer. In all cases the comparison of\nnumerical results showed good agreement with known analytical solutions,\nirrespective of the choice of the fluid properties, geometrical parameters, and\nlattice Boltzmann model, thus demonstrating the robustness of the proposed\nalgorithm.",
        "positive": "Relaxation damping in oscillating contacts: If a contact of two purely elastic bodies with no sliding (infinite\ncoefficient of friction) is subjected to superimposed oscillations in the\nnormal and tangential directions, then a specific damping appears, that is not\ndependent on friction or dissipation in the material. We call this effect\n\"relaxation damping\". The rate of energy dissipation due to relaxation damping\nis calculated in a closed analytic form for arbitrary axially-symmetric\ncontacts. In the case of equal frequency of normal and tangential oscillations,\nthe dissipated energy per cycle is proportional to the square of the amplitude\nof tangential oscillation and to the absolute value of the amplitude of normal\noscillation, and is dependent on the phase shift between both oscillations. In\nthe case of low frequency tangential motion with superimposed high frequency\nnormal oscillations, the system acts as a tunable linear damper. Generalization\nof the results for macroscopically planar, randomly rough surfaces is\ndiscussed."
    },
    {
        "anchor": "Effect of ring stiffness and ambient pressure on the dynamical slowdown\n  in ring polymers: Using extensive molecular dynamics simulations, we investigate the slowing\ndown of dynamics in a 3D system of ring polymers by varying the ambient\npressure and the stiffness of the rings. Our study demonstrates that the\nstiffness of the rings determines the dynamics of the ring polymers, leading to\nglassiness at lower pressures for stiffer rings. The threading of the ring\npolymers, a unique feature that emerges only due to the topological nature of\nsuch polymers in three dimensions, is shown to be the determinant feature of\ndynamical slowing down, albeit only in a certain stiffness range. Our results\nsuggest a possible framework of exploring the phase space spanned by ring\nstiffness and pressure to obtain spontaneously emerging topologically\nconstrained polymer glasses.",
        "positive": "Shape Recovery in Viscoelastic Silicone Rubber and the Fractional Zener\n  Model: Viscoelastic silicone rubber (VSR) is a remarkable shape-memory solid. The\nmaterial's polymer network retains a memory of its shape history, so its\ncurrent and future shapes depend strikingly on its past shapes. Although VSR's\nmemory fades gradually and it has a permanent (cured-in) shape to which it will\neventually return when left alone, VSR can be taught new shapes and retain them\nfor significant lengths of time.\n  To examine VSR's ability to learn, remember, and recover shapes, this work\nfocuses on a simple experiment. A VSR that has relaxed into its permanent shape\nis suddenly compressed to about 80% of its original height. After a specific\nperiod of compression, the VSR is released and allowed to return to its\npermanent shape. Having learned a new shape during the compression period,\nhowever, the VSR is reluctant to return and takes seconds, minutes, or hours to\ndo so, depending on how long it was compressed.\n  In addition to observing these behaviors experimentally in VSR, we show that\nthose behaviors are well-described by the Fractional Zener model. That model\ninvolves time derivatives of non-integer order and those generalized time\nderivatives have memory. Both VSR and the Fractional Zener model describing it\nare acutely aware of the past.\n  The model's mathematical machinery make it possible to design VSR behaviors\nbased on physical parameters, although some of the model's relationships are\nnot yet known in closed form. VSR's existence as a practical material means\nthat devices can be designed and produced that use a memory of past shapes to\ndo things that would otherwise be difficult or impossible to make."
    },
    {
        "anchor": "Structure and Strength at Immiscible Polymer Interfaces: Thermal welding of polymer-polymer interfaces is important for integrating\npolymeric elements into devices. When two different polymers are joined, the\nstrength of the weld depends critically on the degree of immiscibility. We\nperform large-scale molecular dynamics simulations of the structure-strength\nrelation at immiscible polymer interfaces. Our simulations show that\nimmiscibility arrests interdiffusion and limits the equilibrium interfacial\nwidth. Even for weakly immiscible films, the narrow interface is unable to\ntransfer stress upon deformation as effectively as the bulk material, and chain\npullout at the interface becomes the dominant failure mechanism. This greatly\nreduces the interfacial strength. The weak response of immiscible interfaces is\nshown to arise from an insufficient density of entanglements across the\ninterface. We demonstrate that there is a threshold interfacial width below\nwhich no significant entanglements can form between opposite sides to\nstrengthen the interface.",
        "positive": "Polymer translocation through nano-pores in vibrating thin membranes: Polymer translocation is a promising strategy for the next-generation DNA\nsequencing technologies. The use of biological and synthetic nano-pores,\nhowever, still suffers from serious drawbacks. In particular, the width of the\nmembrane layer can accommodate several bases at the same time, making difficult\naccurate sequencing applications. More recently, the use of graphene membranes\nhas paved the way to new sequencing capabilities, with the possibility to\nmeasure transverse currents, among other advances. The reduced thickness of\nthese new membranes poses new questions on the effect of deformability and\nvibrations of the membrane on the translocation process, two features which are\nnot taken into account in the well-established theoretical frameworks. Here, we\nmake a first step forward in this direction. We report numerical simulation\nwork on a model system simple enough to allow gathering significant insight on\nthe effect of these features on the average translocation time, with\nappropriate statistical significance. We have found that the interplay between\nthermal fluctuations and the deformability properties of the nano-pore play a\ncrucial role in determining the process. We conclude by discussing new\ndirections for further work."
    },
    {
        "anchor": "Comment on \"Collective Excitations of a Bose-Einstein Condensate in a\n  Magnetic Trap\": We calculate the damping rate of collective excitations for a nearly pure\nBose-Einstein condensate regarding the recent experiments in MIT [M.-O. Mews et\nal, Phys. Rev. Lett. 77, 988 (1996)]. The decay time of collective excitations\nobtained in our theoretical calculations agrees well with their experimental\nresult. We argue that the damping of collective excitations is due to thermal\ncontributions rather than interactions between collective modes.",
        "positive": "Continuum elastic models for force transmissions in biopolymer gels: We review continuum elastic models for the transmission of both external\nforces and internal active cellular forces in biopolymer gels, and relate them\nto recent experiments. Rather than being exhaustive, we focus on continuum\nelastic models for small affine deformations and intend to provide a systematic\ncontinuum method and some analytical perspectives to the study of force\ntransmissions in biopolymer gels. We start from a very brief review of the\nnonlinear mechanics of individual biopolymers and a summary of constitutive\nmodels for the nonlinear elasticity of biopolymer gels. We next show that the\nsimple 3-chain model can give predictions that well fit the shear experiments\nof some biopolymer gels, including the effects of strain-stiffening and\nnegative normal stress. We then review continuum models for the transmission of\ninternal active forces that are induced by a spherically contracting cell\nembedded in a three-dimensional biopolymer gel. Various scaling regimes for the\ndecay of cell-induced displacements are identified for linear isotropic and\nanisotropic materials, and for biopolymer gels with nonlinear\ncompressive-softening and strain-stiffening elasticity, respectively. After\nthat, we present (using an energetic approach) the generic and unified\ncontinuum theory proposed in [Ben-Yaakov, Soft Matter, 2015, 11, 1412] about\nhow the transmission of forces in the biogel matrix can mediate long-range\ninteractions between cells with mechanical homeostasis. We show the predictions\nof the theory in a special hexagonal multicellular array, and relate them to\nrecent experiments. Finally, we conclude this paper with comments on the\nlimitations and outlook of continuum modeling, and highlight the needs of\ncomplementary theoretical approaches such as discrete network simulations to\nforce transmissions in biopolymer gels and phenomenological active gel theories\nfor multicellular systems."
    },
    {
        "anchor": "The effect of direct electron beam patterning on the water uptake and\n  ionic conductivity of Nafion thin films: We report the effect of electron-beam patterning on the water uptake and\nionic conductivity of Nafion films using a combination of x-ray photoelectron\nspectroscopy, quartz crystal microbalance studies, neutron reflectometry, and\nAC impedance spectroscopy. The aim was to more fully characterize the nature of\nthe nanoscale patterned Nafion structures recently used as a key element in\nnovel ion-to-electron transducers by Gluschke et al. To enable these studies,\nwe develop the electron beam patterning process for large areas, achieving\npatterning speeds approaching 1 cm$^{2}$/hr, and patterned areas as large as 7\ncm$^{2}$ for the neutron reflectometry studies. We ultimately show that\nelectron-beam patterning affects both the water uptake and the ionic\nconductivity, depending on film thickness. We see Type-II adsorption isotherm\nbehaviour for all films. For thick films (~230 nm), we see a strong reduction\nin water uptake with electron-beam patterning. In contrast, for thin films (~30\nnm), electron-beam patterning enhances water uptake. Notably, we find that for\neither thickness the reduction in ionic conductivity arising from electron-beam\npatterning is kept to less than an order of magnitude. We propose mechanisms\nfor the observed behaviour based on the known complex morphology of Nafion\nfilms to motivate future studies of electron-beam processed Nafion.",
        "positive": "Multiscale Simulation of Entangled Polymer Melt with Elastic Deformation: To predict flow behavior of entangled polymer melt, we have developed\nmultiscale simulation composed of Lagrangian fluid particle simulation and\ncoarse-grained polymer dynamics simulation. We have introduced a particle\ndeformation in the Lagrangian fluid particle simulation to describe elongation\nflow at a local point. The particle deformation is obtained to be consistent\nwith the local polymer deformation."
    },
    {
        "anchor": "Sustainable, low-cost sorbents based on calcium chloride-loaded\n  polyacrylamide hydrogels: Sorbents are promising materials for applications in atmospheric water\nharvesting, thermal energy storage, and passive cooling, thereby addressing\ncentral challenges related to water scarcity and the global energy transition.\nRecently, hygroscopic hydrogel composites have emerged as high-performance\nsorbents. However, many of these systems are fabricated with unsustainable and\ncostly sorbent materials, which hinders their wide deployment. Here, the\nsynthesis of high-performance, cost-efficient polyacrylamide hydrogels loaded\nwith unprecedented amounts of calcium chloride is demonstrated. To this end,\nthe swelling procedure of polyacrylamide hydrogels in aqueous calcium chloride\nsolutions is optimized. The achievable salt loading in the hydrogel is\ncharacterized as a function of temperature, calcium chloride concentration in\nthe swelling solution, and the hydrogel preparation conditions. The obtained\nhydrogel-salt composites are shown to be stable under repeated\nsorption-desorption cycling and enable water uptakes of 0.92 and 2.38 grams of\nwater per gram of dry materials at 30% and 70% relative humidity, respectively.\nThe resulting cost-performance ratio substantially exceeds lithium\nchloride-based systems. Further, the mechanistic insights on hydrogel salt\ninteractions can guide the design of sustainable and low-cost sorbent materials\nfor future applications in water and energy.",
        "positive": "Equivalence of quenched and annealed averaging in models of disordered\n  polymers: Equivalence of the influence of quenched and annealed disorder on scaling\nproperties of long flexible polymer chains is proved by analyzing the\nO(m)-symmetric field theory in polymer (de Gennes) limit m \\to 0. Additional\nsymmetry properties of the model in this limit are discussed."
    },
    {
        "anchor": "Spherical-harmonic Expansion of the Modified Diffusion Equation for\n  Wormlike Chain in Curvilinear Coordinates: We investigate the wormlike polymer chains using self-consistent field theory\nand take into account the Onsager excluded-volume interaction between polymer\nsegments. The propagator of polymer chain is one of the essential physical\nquantities used to study the conformation of polymers, which satisfies the\nmodified diffusion equation (MDE) for wormlike chain. The propagator of\nwormlike chain is not only dependent on the spatial variables, but also on the\norientation. We separate the variables of propagator by using\nspherical-harmonic series and then simplify the MDE to a coupled set of\nequations only depends on spatial variables in this paper. We expand the MDE by\nspherical-harmonic functions in cylindrical coordinates and spherical\ncoordinates, respectively. We find that there are three ways to set the\norientation, no matter in cylindrical coordinates or spherical coordinates. But\nfor the convenience of calculation, we compare these three forms and choose the\nsimplest one to simplify the MDE. And we get a coupled set of equations only\ndepends on spatial variables.",
        "positive": "Systematic Coarse-graining of Epoxy Resins with Machine\n  Learning-Informed Energy Renormalization: A persistent challenge in predictive molecular modeling of thermoset polymers\nis to capture the effects of chemical composition and degree of crosslinking\n(DC) on dynamical and mechanical properties with high computational efficiency.\nWe established a new coarse-graining (CG) approach that combines the energy\nrenormalization method with Gaussian process surrogate models of the molecular\ndynamics simulations. This allows a machine-learning informed functional\ncalibration of DC-dependent CG force field parameters. Taking versatile epoxy\nresins consisting of Bisphenol A diglycidyl ether combined with curing agent of\neither 4,4-Diaminodicyclohexylmethane or polyoxypropylene diamines, we\ndemonstrated excellent agreement between all-atom and CG predictions for\ndensity, Debye-Waller factor, Young's modulus and yield stress at any DC. We\nfurther introduce a surrogate model enabled simplification of the functional\nforms of 14 non-bonded calibration parameters by quantifying the uncertainty of\na candidate set of high-dimensional and flexible calibration functions. The\nframework established provides an efficient methodology for chemistry-specific,\nlarge-scale investigations of the dynamics and mechanics of epoxy resins."
    },
    {
        "anchor": "Energy barriers, entropy barriers, and non-Arrhenius behavior in a\n  minimal glassy model: We study glassy dynamics using a simulation of three soft Brownian particles\nconfined to a two-dimensional circular region. If the circular region is large,\nthe disks freely rearrange, but rearrangements are rarer for smaller system\nsizes. We directly measure a one-dimensional free energy landscape\ncharacterizing the dynamics. This landscape has two local minima corresponding\nto the two distinct disk configurations, separated by a free energy barrier\nwhich governs the rearrangement rate. We study several different interaction\npotentials and demonstrate that the free energy barrier is composed of a\npotential energy barrier and an entropic barrier. The heights of both of these\nbarriers depend on temperature and system size, demonstrating how non-Arrhenius\nbehavior can arise close to the glass transition.",
        "positive": "Contact-line pinning controls how quickly colloidal particles\n  equilibrate with liquid interfaces: Previous experiments have shown that spherical colloidal particles relax to\nequilibrium slowly after they adsorb to a liquid-liquid interface, despite the\nlarge interfacial energy gradient driving the adsorption. The slow relaxation\nhas been explained in terms of transient pinning and depinning of the contact\nline on the surface of the particles. However, the nature of the pinning sites\nhas not been investigated in detail. We use digital holographic microscopy to\ntrack a variety of colloidal spheres---inorganic and organic, charge-stabilized\nand sterically stabilized, aqueous and non-aqueous---as they breach liquid\ninterfaces. We find that nearly all of these particles relax logarithmically in\ntime over timescales much larger than those expected from viscous dissipation\nalone. By comparing our results to theoretical models of the pinning dynamics,\nwe infer the area per defect to be on the order of a few square nanometers for\neach of the colloids we examine, whereas the energy per defect can vary from a\nfew $kT$ for non-aqueous and inorganic spheres to tens of $kT$ for aqueous\npolymer particles. The results suggest that the likely pinning sites are\ntopographical features inherent to colloidal particles---surface roughness in\nthe case of silica particles and grafted polymer \"hairs\" in the case of polymer\nparticles. We conclude that the slow relaxation must be taken into account in\nexperiments and applications, such as Pickering emulsions, that involve\ncolloids attaching to interfaces. The effect is particularly important for\naqueous polymer particles, which pin the contact line strongly."
    },
    {
        "anchor": "Dielectric relaxation and crystallization behaviour of amorphous\n  nilutamide: The molecular mobility of glass and supercooled liquid states of nilutamide\nhas been studied with broadband dielectric spectroscopy for a wide range of\ntemperature and frequency. Besides primary $\\alpha$-relaxation an excess wing\nlike secondary relaxation is observed. The temperature dependence of structural\n$\\alpha$-relaxation show non-Arrhenius behaviour, and follows\nVogel-Fulcher-Tammann (VFT) empirical formula. The glass transition\ntemperature, T$_{g}$=302K and fragility index, m=76 are obtained from the VFT\nparameters. The structural $\\alpha$-relaxation process is non-Debye with\nKohlraush-Williams-Watts stretched exponential $\\beta_{KWW}$=0.76. Secondary\nrelaxation time of nilutamide coincides with the primitive relaxation time\ncalculated from the coupling model. Hence the secondary relaxation process of\nnilutamide is treated as the Johari-Goldstein (JG) $\\beta$-process, which is\nthe precursor of the structural $\\alpha$-process. Recent report on nilutamide\nindicates the increase of nucleation even below T$_{g}$, however we attributed\nto the JG $\\beta$-relaxation. During the dielectric measurements amorphous\nnilutamide recrystallizes. The crystallization of amorphous nilutamide has been\nstudied by the isotherm dielectric measurements at T=326K over a period of\ntime. The crystallization follows Avrami equation and the parameters are\nobtained.",
        "positive": "Parametric excitation of wrinkles in elastic sheets on elastic and\n  viscoelastic substrates: Thin elastic sheets supported on compliant media form wrinkles under lateral\ncompression. Since the lateral pressure is coupled to the sheet's deformation,\nvarying it periodically in time creates a parametric excitation. We study the\nresulting parametric resonance of wrinkling modes in sheets supported on\nsemi-infinite elastic or viscoelastic media, at pressures smaller than the\ncritical pressure of static wrinkling. We find distinctive behaviors as a\nfunction of excitation amplitude and frequency, including (a) a different\ndependence of the dynamic wrinkle wavelength on sheet thickness compared to the\nstatic wavelength; and (b) a discontinuous decrease of the wrinkle wavelength\nupon increasing excitation frequency at sufficiently large pressures. In the\ncase of a viscoelastic substrate, resonant wrinkling requires crossing a\nthreshold of excitation amplitude. The frequencies for observing these\nphenomena in relevant experimental systems are of the order of a kilohertz and\nabove. We discuss experimental implications of the results."
    },
    {
        "anchor": "Shear-induced polydomain structures of nematic lyotropic chromonic\n  liquid crystal disodium cromoglycate: Lyotropic chromonic liquid crystals (LCLCs) represent aqueous dispersions of\norganic disk-like molecules that form cylindrical aggregates. Despite the\ngrowing interest in these materials, their flow behavior is poorly understood.\nHere, we explore the effect of shear on dynamic structures of the nematic LCLC,\nformed by 14wt ${\\%}$ water dispersion of disodium cromoglycate (DSCG). We\nemploy in-situ polarizing optical microscopy (POM) and small-angle and\nwide-angle X-ray scattering (SAXS/WAXS) to obtain independent and complementary\ninformation on the director structures over a wide range of shear rates. The\nDSCG nematic shows a shear-thinning behavior with two shear-thinning regions\n(Region I at $\\dot{\\gamma}<1\\,s^{-1}$ and Region III at $\\dot{\\gamma}>10\ns^{-1}$) separated by a pseudo-Newtonian Region II ($1 s^{-1}<\\dot{\\gamma}<10\ns^{-1}$). The material is of a tumbling type. In Region I, $\\dot{\\gamma}<1\ns^{-1}$, the director realigns along the vorticity axis. An increase of\n$\\dot{\\gamma}$ above $1 s^{-1}$ triggers nucleation of disclination loops. The\ndisclinations introduce patches of the director that deviates from the\nvorticity direction and form a polydomain texture. Extension of the domains\nalong the flow and along the vorticity direction decreases with the increase of\nthe shear rate to $10 s^{-1}$. Above $10 s^{-1}$, the domains begin to elongate\nalong the flow. At $\\dot{\\gamma}>100 s^{-1}$, the texture evolves into periodic\nstripes in which the director is predominantly along the flow with left and\nright tilts. The period of stripes decreases with an increase of\n$\\dot{\\gamma}$. The shear-induced transformations are explained by the balance\nof the elastic and viscous energies. In particular, nucleation of disclinations\nis associated with an increase of the elastic energy at the walls separating\nnonsingular domains with different director tilts.",
        "positive": "Magnetic alignment of block copolymer microdomains by intrinsic chain\n  anisotropy: We examine the role of intrinsic chain susceptibility anisotropy in magnetic\nfield directed self-assembly of a block copolymer using \\textit{in situ} X-ray\nscattering. Alignment of a lamellar mesophase is observed on cooling across the\ndisorder-order transition with the resulting orientational order inversely\nproportional to the cooling rate. We discuss the origin of the susceptibility\nanisotropy, $\\Delta\\chi$, that drives alignment, and calculate its magnitude\nusing coarse-grained molecular dynamics to sample conformations of\nsurface-tethered chains, finding $\\Delta\\chi\\approx 2\\times10^{-8}$. From\nfield-dependent scattering data we estimate grains of $\\approx1.2$ $\\mu$m are\npresent during alignment. These results demonstrate that intrinsic anisotropy\nis sufficient to support strong field-induced mesophase alignment and suggest a\nversatile strategy for field control of orientational order in block\ncopolymers."
    },
    {
        "anchor": "The effect of contact torques on porosity of cohesive powders: The porosity of uniaxially compacted cohesive powders depends on the applied\nstress (including gravity). The case, where these stresses are weak, is\nconsidered. The compaction results in a porosity which is a function of\nsliding, rolling and torsion friction. By contact dynamics simulations it is\nshown that the influences of contact torques (static rolling and torsion\nfriction) on the porosity are significant and approximately additive. The\nrelevance for nano-powder pressure sintering is discussed.",
        "positive": "Conformations of confined biopolymers: Nanoscale and microscale confinement of biopolymers naturally occurs in cells\nand has been recently achieved in artificial structures designed for\nnanotechnological applications. Here, we present an extensive theoretical\ninvestigation of the conformations and shape of a biopolymer with varying\nstiffness confined to a narrow channel. Combining scaling arguments, analytical\ncalculations, and Monte Carlo simulations, we identify various scaling regimes\nwhere master curves quantify the functional dependence of the polymer\nconformations on the chain stiffness and strength of confinement."
    },
    {
        "anchor": "Bonded straight and helical flagellar filaments form ultra-low-density\n  glasses: We study how the three-dimensional shape of rigid filaments determines the\nmicroscopic dynamics and macroscopic rheology of entangled semi-dilute Brownian\nsuspensions. To control the filament shape we use bacterial flagella, which are\nmicron-long helices assembled from flagellin monomers. We compare the dynamics\nof straight rods, helical filaments, and shape diblock copolymers composed of\nseamlessly joined straight and helical segments. Caged by their neighbors,\nstraight rods preferentially diffuse along their long axis, but exhibit\nsignificantly suppressed rotational diffusion. Entangled helical filaments\nescape their confining tube by corkscrewing through the dense obstacles created\nby other filaments. By comparison, the adjoining segments of the rod-helix\nshape-diblocks suppress both the translation and the corkscrewing dynamics, so\nthat shape-diblocks become permanently jammed at exceedingly low densities. We\nalso measure the rheological properties of semi-dilute suspensions and relate\ntheir mechanical properties to the microscopic dynamics of constituent\nfilaments. In particular, rheology shows that an entangled suspension of shape\nrod-helix copolymers forms a low-density glass whose elastic modulus can be\nestimated by accounting for how shear deformations reduce the entropic degrees\nof freedom of constrained filaments. Our results demonstrate that the\nthree-dimensional shape of rigid filaments can be used to design rheological\nproperties of semi-dilute fibrous suspensions.",
        "positive": "Dependence of Adhesive Friction on Surface Roughness and Elastic Modulus: When adhesive elastomeric materials slide over hard rough surfaces at low\nvelocities, there are two primary dissipative mechanisms that control how\nfriction changes with sliding velocity: viscoelastic dissipation and adhesive\ndissipation. To distinguish the contribution of these dissipative mechanisms we\nhave measured frictional shear stresses for crosslinked polydimethylsiloxane\n(PDMS) on three different rough surfaces of similar surface chemistry across\nnearly six decades of sliding velocity. The results show that the observed\nfriction is dominated by adhesive dissipation, rather than viscoelastic\ndissipation. Prior models for elastomer friction assume that roughness only\ninfluences adhesive dissipation via the amount of contact area; by contrast, we\nfind that the roughness-induced oscillations occurring across all length scales\nfrom macroscopic to atomic influence the molecular processes governing the\nadhesive dissipation. While it was previously known that roughness-induced\noscillations affected the viscoelastic dissipation; this is the first\ndemonstration that these oscillations also control the behavior of the adhesive\ncomponent of friction. Finally, while theory predicts that rough friction\nshould be independent of elastic modulus ($E'$), we show that a strong\ndependence on modulus, with the frictional shear stress scaling as $E'^{1/2}$.\nWhen analyzed in this way, data from four different moduli and three different\nroughnesses collapse onto a universal curve to describe the velocity-dependent\nfriction of soft materials. Taken together, this investigation sheds new light\non the adhesive component of friction, and how it depends on the roughness and\nstiffness of the materials."
    },
    {
        "anchor": "Wave attenuation in glasses: Rayleigh and generalized-Rayleigh\n  scattering scaling: The attenuation of long-wavelength phonons (waves) by glassy disorder plays a\ncentral role in various glass anomalies, yet it is neither fully characterized,\nnor fully understood. Of particular importance is the scaling of the\nattenuation rate $\\Gamma(k)$ with small wavenumbers $k\\!\\to\\!0$ in the\nthermodynamic limit of macroscopic glasses. Here we use a combination of theory\nand extensive computer simulations to show that the macroscopic low-frequency\nbehavior emerges at intermediate frequencies in finite-size glasses, above a\nrecently identified crossover wavenumber $k_\\dagger$, where phonons are no\nlonger quantized into bands. For $k\\!<\\!k_\\dagger$, finite-size effects\ndominate $\\Gamma(k)$, which is quantitatively described by a theory of\ndisordered phonon bands. For $k\\!>\\!k_\\dagger$, we find that $\\Gamma(k)$ is\naffected by the number of quasilocalized nonphononic excitations, a generic\nsignature of glasses that feature a universal density of states. In particular,\nwe show that in a frequency range in which this number is small, $\\Gamma(k)$\nfollows a Rayleigh scattering scaling $\\sim\\!k^{d+1}$ ($d$ is the spatial\ndimension), and that in a frequency range in which this number is sufficiently\nlarge, the recently observed generalized-Rayleigh scaling of the form\n$\\sim\\!k^{d+1}\\log\\!{(k_0/k)}$ emerges ($k_0\\!>k_\\dagger$ is a characteristic\nwavenumber). Our results suggest that macroscopic glasses --- and, in\nparticular, glasses generated by conventional laboratory quenches that are\nknown to strongly suppress quasilocalized nonphononic excitations --- exhibit\nRayleigh scaling at the lowest wavenumbers $k$ and a crossover to\ngeneralized-Rayleigh scaling at higher $k$. Some supporting experimental\nevidence from recent literature is presented.",
        "positive": "Reversible Gel Formation of Triblock Copolymers Studied by Molecular\n  Dynamics Simulation: Molecular dynamics simulations have been employed to study the formation of a\nphysical (thermoreversible) gel by amphiphilic A-B-A triblock copolymers in\naqueous solution. In order to mimic the structure of hydrogel-forming\npolypeptides employed in experiments [W.A. Petka et al., Science 281, 389\n(1998)], the endblocks of the polymer chains are modeled as hydrophobic rods\nrepresenting the alpha-helical part of the polypeptides whereas the central\nB-block is hydrophilic and semi-flexible. We have determined structural\nproperties, such as the hydrophobic cluster-size distribution function, the\ngeometric percolation point and pair correlation functions, and related these\nto the dynamical properties of the system. Upon decrease of the temperature, a\nnetwork structure is formed in which bundles of endblocks act as network\njunctions. Both at short and medium distances an increased ordering is\nobserved, as characterized by the pair correlation function. Micelle formation\nand the corresponding onset of geometric percolation induce a strong change in\ndynamical quantities, e.g., in the diffusion constant and the viscosity, and\ncauses the system to deviate from the Stokes-Einstein relation. The dynamical\nproperties show a temperature dependence that is strongly reminiscent of the\nbehavior of glass-forming liquids. The appearance of a plateau in the stress\nautocorrelation function suggests that the system starts to exhibit a\nsolid-like response to applied stress once the network structure has been\nformed, although the actual sol-gel transition occurs only at a considerably\nlower temperature."
    },
    {
        "anchor": "Ice-templating beet-root pectin foams: Controlling texture, mechanics\n  and capillary properties: Sugar beet pectin is a byproduct of the sugar industry with a particularly\nlow gelling power which hinders its application as gelling agent and thickener.\nHere we consider the use of freeze casting to shape sugar beet pectin into\nlightweight foams. Freeze casting processing conditions such as the applied\nthermal gradient and the polysaccharide concentration were explored to obtain\nmacroporous lightweight foams with different textures. The precise control over\nthe foams texture and pore anisotropy was decisive for their performance as\nliquid transport devices by capillary ascension and for their mechanical\nperformance. Overall, the obtained results show that the formation of highly\nanisotropic structures using freeze casting can be instrumental in the\nupcycling of polysaccharide industrial byproducts.",
        "positive": "Using Thermal Ratchet Mechanism to Achieve Net Motility in Magnetic\n  Microswimmers: Thermal ratchets can extract useful work from random fluctuations. This is\ncommon in the molecular scale, such as motor proteins, and has also been used\nto achieve directional transport in microfluidic devices. In this work, we use\nthe ratchet principle to induce net motility in an externally powered magnetic\ncolloid, which otherwise shows reciprocal (back and forth) motion. The\nexperimental system is based on ferromagnetic micro helices driven by\noscillating magnetic fields, where the reciprocal symmetry is broken through\nasymmetric actuation timescales. The swimmers show net motility with an\nenhanced diffusivity, in agreement with the numerical calculations. This new\nclass of microscale, magnetically powered, active colloids can provide a\npromising experimental platform to simulate diverse active matter phenomena in\nthe natural world."
    },
    {
        "anchor": "Clusters of proteins in bio-membranes: insights into the roles of\n  interaction potential shapes and of protein diversity: It has recently been proposed that proteins embedded in lipidic bio-membranes\ncan spontaneously self-organize into stable small clusters, or membrane\nnano-domains, due to the competition between short-range attractive and\nlonger-range repulsive forces between proteins, specific to these systems. In\nthis paper, we carry on our investigation, by Monte Carlo simulations, of\ndifferent aspects of cluster phases of proteins in bio-membranes. First, we\ncompare different long-range potentials (including notably three-body terms) to\ndemonstrate that the existence of cluster phases should be quite generic.\nFurthermore, a real membrane contains hundreds of different protein species\nthat are far from being randomly distributed in these nano-domains. We take\nthis protein diversity into account by modulating protein-protein interaction\npotentials both at short and longer range. We confirm theoretical predictions\nin terms of biological cluster specialization by deciphering how clusters\nrecruit only a few protein species. In this respect, we highlight that cluster\nphases can turn out to be an advantage at the biological level, for example by\nenhancing the cell response to external stimuli.",
        "positive": "Efficient sampling of reversible cross-linking polymers: Self-assembly\n  of single-chain polymeric nanoparticles: We present a new simulation technique to study systems of polymers\nfunctionalized by reactive sites that bind/unbind forming reversible linkages.\nFunctionalized polymers feature self-assembly and responsive properties that\nare unmatched by systems lacking selective interactions. The scales at which\nthe functional properties of these materials emerge are difficult to model,\nespecially in the reversible regime where such properties result from many\nbinding/unbinding events. This difficulty is related to large entropic barriers\nassociated with the formation of intra-molecular loops. In this work we present\na simulation scheme that sidesteps configurational costs by dedicated Monte\nCarlo moves capable of binding/unbinding reactive sites in a single step.\nCross-linking reactions are implemented by trial moves that reconstruct chain\nsections attempting, at the same time, a dimerization reaction between pairs of\nreactive sites. The model is parametrized by the reaction equilibrium constant\nof the reactive species free in solution. This quantity can be obtained by\nmeans of experiments or atomistic/quantum simulations. We use the proposed\nmethodology to study self-assembly of single--chain polymeric nanoparticles,\nstarting from flexible precursors carrying regularly or randomly distributed\nreactive sites. During a single run, almost all pairs of reactive monomers\ninteract at least once. We focus on understanding differences in the morphology\nof chain nanoparticles when linkages are reversible as compared to the well\nstudied case of irreversible reactions. Intriguingly, we find that the size of\nregularly functionalsized chains, in good solvent conditions, is non-monotonous\nas a function of the degree of functionalization. We clarify how this result\nfollows from excluded volume interactions and is peculiar of reversible\nlinkages and regular functionalizations."
    },
    {
        "anchor": "High-frequency rheological behaviour of a multiconnected lyotropic phase: High-frequency (up to ${\\omega} = 6 \\, 10^4$ rad/s) rheological measurements\ncombined with light-scattering investigations show that an isotropic and\nmulticonnected phase of surfactant micelles exhibits a terminal relaxation time\nof a few {\\mu}s, much smaller than in solutions of entangled wormlike micelles.\nThis result is explained in terms of the local hexagonal order of the\nmicroscopic structure and we discuss its relevance for the understanding of\ndynamic behaviour in related systems, such as wormlike micelles and sponge\nphases.",
        "positive": "Criticality in vibrated frictional flows at finite strain rate: We evidence critical fluctuations in the strain-rate of granular flows that\nare weakly vibrated. Strikingly, the critical point arises at {\\em finite}\nvalues of the mean strain rate and vibration strength, far away from the\nyielding critical point at zero flow rate. We show that the global rheology, as\nwell as the amplitude and correlation time of the fluctuations, are consistent\nwith a mean-field, Landau like description, where strain rate and stress act as\nconjugated variables. We introduce a general model which captures the observed\nphenomenology, and argue that this type of critical behavior generically arises\nwhen self fluidization competes with friction."
    },
    {
        "anchor": "How to reduce the crack density in drying colloidal material?: The drying of a colloidal dispersion can result in a gel phase defined as a\nporous matrix saturated in solvent. During the drying process, high mechanical\nstresses are generated. When these stresses exceed the strength of the\nmaterial, they can be released in the formation of cracks. This process\nstrongly depends on both the mechanical properties of the material and the way\nthe gel consolidates. In this report, we give experimental evidences that the\nnumber of cracks formed in the consolidating film depend on the drying rate,\nthe nature of the solvent and the mechanical properties of the colloidal\nparticles.",
        "positive": "DNA hairpins primarily promote duplex melting rather than inhibiting\n  hybridization: The effect of secondary structure on DNA duplex formation is poorly\nunderstood. We use a coarse-grained model of DNA to show that specific 3- and\n4-base pair hairpins reduce hybridization rates by factors of 2 and 10\nrespectively, in good agreement with experiment. By contrast, melting rates are\naccelerated by factors of ~100 and ~2000. This surprisingly large speed-up\noccurs because hairpins form during the melting process, stabilizing partially\nmelted states, and facilitating dissociation. These results may help guide the\ndesign of DNA devices that use hairpins to modulate hybridization and\ndissociation pathways and rates."
    },
    {
        "anchor": "General procedure for solution of contact problems under dynamic normal\n  and tangential loading based on the known solution of normal contact problem: In the present paper we show that the normal contact problem between two\nelastic bodies in the halfspace approximation can always be transformed to an\nequivalent problem of the indentation of a profile into an elastic Winkler\nfoundation. Once determined, the equivalent profile can be used also for\ntangential contact problems and arbitrary superimposed normal and tangential\nloading histories as well as for treating of contact problems with linearly\nviscoelastic bodies. In the case of axis-symmetric shapes, the equivalent\nprofile is given by the MDR integral transformation. For all other shapes, the\nprofile is deduced from the solution of the elastic contact normal problem,\nwhich can be obtained numerically or experimentally.",
        "positive": "Charge-Driven Liquid-Crystalline Behavior of Ligand-Functionalized\n  Nanorods in Apolar Solvent: Concentrated colloidal suspensions of nanorods often exhibit\nliquid-crystalline (LC) behavior. The transition to a nematic LC phase, with\nlong-range orientational order of the particles, is usually well captured by\nOnsager's theory for hard rods, at least qualitatively. The theory shows how\nthe volume fraction at the transition decreases with increasing aspect ratio of\nthe rods. It also explains that the long-range electrostatic repulsive\ninteraction occurring between rods stabilized by their surface charge can\nsignificantly increase their effective diameter, resulting in a decrease of the\nvolume fraction at the transition, as compared to sterically stabilized rods.\nHere, we report on a system of ligand-stabilized LaPO4 nanorods, of aspect\nratio around 11, dispersed in apolar medium exhibiting the counter-intuitive\nobservation that the onset of nematic self-assembly occurs at an extremely low\nvolume fraction of around 0.25%, which is lower than observed (around 3%) with\nthe same particles when charge-stabilized in polar solvent. Furthermore, the\nnanorod volume fraction at the transition increases with increasing\nconcentration of ligands, in a similar way as in polar media where increasing\nthe ionic strength leads to surface-charge screening. This peculiar system was\ninvestigated by dynamic light scattering, Fourier-Transform Infra-Red\nspectroscopy, zetametry, electron microscopy, polarized-light microscopy,\nphotoluminescence measurements, and X-ray scattering. Based on these\nexperimental data, we formulate several tentative scenarios that might explain\nthis unexpected phase behavior. However, at this stage, its full understanding\nremains a pending theoretical challenge. Nevertheless, this study shows that\ndispersing anisotropic nanoparticles in an apolar solvent may sometimes lead to\nspontaneous ordering events that defy our intuitive ideas about colloidal\nsystems."
    },
    {
        "anchor": "Avoiding Infrared Catastrophes in Trapped Bose-Einstein Condensates: This paper is concerned with the long wavelength instabilities (infrared\ncatastrophes) occurring in Bose-Einstein condensates (BECs). We examine the\nmodulational instability in ``cigar-shaped'' (1D) attractive BECs and the\ntransverse instability of dark solitons in ``pancake'' (2D) repulsive BECs. We\nsuggest mechanisms, and give explicit estimates, on how to ``engineer'' the\ntrapping conditions of the condensate to avoid such instabilities: the main\nresult being that a tight enough trapping potential suppresses the\ninstabilities present in the homogeneous limit. We compare the obtained\nestimates with numerical results and we highlight the relevant regimes of\ndynamical behavior.",
        "positive": "Focusing by blocking: repeatedly generating central density peaks in\n  self-propelled particle systems by exploiting diffusive processes: Over the past few years the displacement statistics of self-propelled\nparticles has been intensely studied, revealing their long-time diffusive\nbehavior. Here, we demonstrate that a concerted combination of boundary\nconditions and switching on and off the self-propelling drive can generate and\nafterwards arbitrarily often restore a non-stationary centered peak in their\nspatial distribution. This corresponds to a partial reversibility of their\nstatistical behavior, in opposition to the above-mentioned long-time diffusive\nnature. Interestingly, it is a diffusive process that mediates and makes\npossible this procedure. It should be straightforward to verify our predictions\nin a real experimental system."
    },
    {
        "anchor": "Active Brownian and inertial particles in disordered environments:\n  short-time expansion of the mean-square displacement: We consider an active Brownian particle moving in a disordered\ntwo-dimensional energy or motility landscape. The averaged\nmean-square-displacement (MSD) of the particle is calculated analytically\nwithin a systematic short-time expansion. As a result, for overdamped\nparticles, both an external random force field and disorder in the\nself-propulsion speed induce ballistic behaviour adding to the ballistic regime\nof an active particle with sharp self-propulsion speed. Spatial correlations in\nthe force and motility landscape contribute only to the cubic and higher order\npowers in time for the MSD. Finally, for inertial particles two superballistic\nregimes are found where the scaling exponent of the MSD with time is $\\alpha=3$\nand $\\alpha=4$.\n  We confirm our theoretical predictions by computer simulations. Moreover they\nare verifiable in experiments on self-propelled colloids in random\nenvironments.",
        "positive": "Topological and geometric measurements of force chain structure: Developing quantitative methods for characterizing structural properties of\nforce chains in densely packed granular media is an important step toward\nunderstanding or predicting large-scale physical properties of a packing. A\npromising framework in which to develop such methods is network science, which\ncan be used to translate particle locations and force contacts to a graph in\nwhich particles are represented by nodes and forces between particles are\nrepresented by weighted edges. Applying network-based community-detection\ntechniques to extract force chains opens the door to developing statistics of\nforce chain structure, with the goal of identifying shape differences across\npackings, and providing a foundation on which to build predictions of bulk\nmaterial properties from mesoscale network features. Here, we discuss a trio of\nrelated but fundamentally distinct measurements of mesoscale structure of force\nchains in arbitrary 2D packings, including a novel statistic derived using\ntools from algebraic topology, which together provide a tool set for the\nanalysis of force chain architecture. We demonstrate the utility of this tool\nset by detecting variations in force chain architecture with pressure.\nCollectively, these techniques can be generalized to 3D packings, and to the\nassessment of continuous deformations of packings under stress or strain."
    },
    {
        "anchor": "Cavity Growth in Soft Solids: Soft polymer-based solid materials can be defined as solid materials with\nelastic moduli below 1 MPa. In order to obtain such a low modulus while\nretaining a solid character, all these materials are based on a network of\nfixed points (crosslinks, physical interactions) keeping together a liquid-like\nmatrix. Since they are not able to flow, very large deformations will lead to\nfailure by fracture or cavitation. We discuss in this paper new experimental\ndata suggesting that the growth of a cavity in a soft nearly elastic solid\nundergoes a transition from a stress-controlled growth, when the initial cavity\nsize is larger than Gc/E, to an energy-activated growth, when the initial\ncavity size is smaller than Gc/E. The important material length scale Gc/E\nrepresents the ratio between the surface energy necessary to expand the cavity\nand the elastic modulus. This energy activated growth regime is due to the\nexistence of a metastable solution and significantly increases the apparent\ncavitation stress for layers thinner than 1000 Gc/E.",
        "positive": "Origin of the Sub-diffusive Behavior and Crossover From a Sub-diffusive\n  to a Super-diffusive Dynamics Near a Biological Surface: Diffusion of a tagged particle near a constraining biological surface is\nexamined numerically by modeling the surface-water interaction by an effective\npotential. The effective potential is assumed to be given by an asymmetric\ndouble well constrained by a repulsive surface towards $r=0$ and unbound at\nlarge distances. The time and space dependent probability distribution $P(r,t)$\nof the underlying Smoluchowski equation is solved by using Crank-Nicholson\nmethod. The mean square displacement shows a transition from sub-diffusive\n(exponent $\\alpha \\sim$ 0.43) to a super-diffusive (exponent $\\alpha \\sim$\n1.75) behavior with time and ultimately to a diffusive dynamics. The decay of\nself intermediate scattering function ($F_{s}(k,t)$) is non-exponential in\ngeneral and shows a power law behavior at the intermediate time. Such features\nhave been observed in several recent computer simulation studies on dynamics of\nwater in protein and micellar hydration shell. The present analysis provides a\nsimple microscopic explanation for the transition from the sub-diffusivity and\nsuper-diffusivity. {\\em The super-diffusive behavior is due to escape from the\nwell near the surface and the sub-diffusive behavior is due to return of\nquasi-free molecules to form the bound state again, after the initial escape}"
    },
    {
        "anchor": "On the convergence of multiplicative branching processes in dynamics of\n  fluid flows: The Brownian motion over the space of fluid velocity configurations driven by\nthe hydrodynamical equations is considered. The Green function is computed in\nthe form of an asymptotic series close to the standard diffusion kernel. The\nhigh order asymptotic coefficients are studied. Similarly to the models of\nquantum field theory, the asymptotic contributions demonstrate the factorial\ngrowth and are summated by means of Borel's procedure. The resulting corrected\ndiffusion spectrum has a closed analytical form. The approach provides a\npossible ground for the optimization of existing numerical simulation\nalgorithms and can be used in purpose of analysis of other asymptotic series in\nturbulence.",
        "positive": "Programming Interactions in Magnetic Handshake Materials: The ability to rapidly manufacture building blocks with specific binding\ninteractions is a key aspect of programmable assembly. Recent developments in\nDNA nanotechnology and colloidal particle synthesis have significantly advanced\nour ability to create particle sets with programmable interactions, based on\nDNA or shape complementarity. The increasing miniaturization underlying\nmagnetic storage offers a new path for engineering programmable components for\nself assembly, by printing magnetic dipole patterns on substrates using\nnanotechnology. How to efficiently design dipole patterns for programmable\nassembly remains an open question as the design space is combinatorially large.\nHere, we present design rules for programming these magnetic interactions. By\noptimizing the structure of the dipole pattern, we demonstrate that the number\nof independent building blocks scales super linearly with the number of printed\ndomains. We test these design rules using computational simulations of self\nassembled blocks, and experimental realizations of the blocks at the mm scale,\ndemonstrating that the designed blocks give high yield assembly. In addition,\nour design rules indicate that with current printing technology, micron sized\nmagnetic panels could easily achieve hundreds of different building blocks."
    },
    {
        "anchor": "Formation of dilute adhesion domains driven by weak elasticity-mediated\n  interactions: Cell-cell adhesion is established by specific binding of receptor and ligand\nproteins. The adhesion bonds attract each other and often aggregate into large\nclusters that are central to many biological processes. One possible origin of\nattractive interactions between adhesion bonds is the elastic response of the\nmembranes to their deformation by the bonds. Here, we analyze these\nelasticity-mediated interactions using a novel mean-field approach. Analysis of\nsystems at different densities of bonds, $\\phi$, reveals that the phase diagram\nexhibits a nearly-universal behavior when the temperature $T$ is plotted vs.\nthe scaled density $x=\\phi \\xi^2$, where $\\xi$ is the linear size of the\nmembrane's region affected by a single bond. The critical point $(\\phi_c,T_c)$\nis located at very low densities and slightly below $T_c$ we identify phase\ncoexistence between two low-density phases. Dense domains are observed only\nwhen the height by which the bonds deform the membranes, $h_0$, is much larger\nthan their thermal roughness, $\\Delta$, which occurs at very low temperatures\n$T\\ll T_c$. We conclude that the elasticity-mediated interactions are weak and\ncannot be regarded as responsible for the formation of dense adhesion domains.\nThe weakness of the elasticity-mediated effect and its relevance to dilute\nsystems only can be attributed to the fact that the membrane's elastic energy\nsaturates in the semi-dilute regime, when the typical spacing between the bonds\n$r\\gtrsim \\xi$, i.e., for $x\\lesssim 1$. Therefore, at higher densities, only\nthe mixing entropy of the bonds (which favors uniform distributions) is\nthermodynamically relevant. We discuss the implications of our results to the\nquestion of immunological synapse formation, and demonstrate the\nelasticity-mediated interactions may be involved in the aggregation of these\nsemi-dilute membrane domains.",
        "positive": "SWENet: a physics-informed deep neural network (PINN) for shear wave\n  elastography: Shear wave elastography (SWE) enables the measurement of elastic properties\nof soft materials, including soft tissues, in a non-invasive manner and finds\nbroad applications in a variety of disciplines. The state-of-the-art SWE\nmethods commercialized in various instruments rely on the measurement of shear\nwave velocities to infer material parameters and have relatively low resolution\nand accuracy for inhomogeneous soft materials due to the complexity of wave\nfields. In the present study, we overcome this challenge by proposing a\nphysics-informed neural network (PINN)-based SWE (SWENet) method considering\nthe merits of PINN in solving an inverse problem. The spatial variation of\nelastic properties of inhomogeneous materials has been defined in governing\nequations, which are encoded in PINN as loss functions. Snapshots of wave\nmotion inside a local region have been used to train the neural networks, and\nduring this course, the spatial distribution of elastic properties is inferred\nsimultaneously. Both finite element simulations and tissue-mimicking phantom\nexperiments have been performed to validate the method. Our results show that\nthe shear moduli of soft composites consisting of matrix and inclusions of\nseveral millimeters in cross-section dimensions with either regular or\nirregular geometries can be identified with good accuracy. The advantages of\nthe SWENet over conventional SWE methods consist of using more features of the\nwave motion in inhomogeneous soft materials and enabling seamless integration\nof multi-source data in the inverse analysis. Given the advantages of the\nreported method, it may find applications including but not limited to\nmechanical characterization of artificial soft biomaterials, imaging elastic\nproperties of nerves in vivo, and differentiating small malignant tumors from\nbenign ones by quantitatively measuring their distinct stiffnesses."
    },
    {
        "anchor": "Dimensional crossover and quantum effects of gases adsorbed on nanotube\n  bundles: Adsorption properties of several gases (Ne, CH4, Ar, Xe) on the external\nsurface of a carbon nanotube bundle are investigated. Calculations are\nperformed at low coverage and variable temperature, and for some temperatures\nas a function of coverage. Within a simple model (in the limit of very low\ncoverage) we are able to study the evolution of the film's thermal properties\nfrom those of a one dimensional (1D) fluid to those of a 2D film. In addition,\ngrand canonical Monte Carlo simulations are performed in order to identify a\nsecond layer groove phase, which occurs once a monolayer of atoms covers the\nexternal surface. We derive from the simulations the isosteric heat,\ncompresibility and specific heat as a function of coverage. We evaluate\nalternative models in order to derive quantum corrections to the classical\nresults. We compare our findings with those of recent adsorption experiments.",
        "positive": "Toy models of multibranched polymers: opened vs. circular structures: We study the conformational properties of complex Gaussian polymers\ncontaining $f_c$ linear branches and $f_r$ closed loops, periodically tethered\nat $n$ branching points to either a linear polymer backbone (generalized\nbottlebrush structures) or closed polymer ring (decorated ring structure).\nApplying the path integration method, based on Edwards continuous chain model,\nwe obtain in particular the exact values for the size ratios comparing the\ngyration radii of considered complex structures and linear chains of the same\ntotal molecular weight, as functions of $n$, $f_c$ and $f_r$. Compactification\nof the overall effective size of branched macromolecules with the increasing\nnumber of loops is quantitatively confirmed. Our results are supported by\nnumerical estimates obtained by application of Wei's method."
    },
    {
        "anchor": "A novel view on classification of glass-forming liquids and empirical\n  viscosity model: In the last few decades, theoretical and experimental studies of\nglass-forming liquids have revealed presence of universal regularities in the\nviscosity-temperature data. In the present work, we propose a viscosity model\nfor scaling description of experimental viscosity data. A feature of this model\nis presence of only two adjustable parameters and high accuracy of experimental\ndata approximation by this model for a wide temperature range. The basis of the\nscaling description is an original temperature scale. Within this scaling\ndescription we obtain the transformed Angell plot, in which the area separating\n\"fragile\" and \"strong\" glass-formers emerges. The proposed scaling procedure\nmake it possible to reconsider belonging some liquids to the type of \"fragile\"\nglass-formers. The obtained results form basis for development of a generalized\nscaling description of crystallization kinetics in supercooled liquids and\nglasses.",
        "positive": "A microscopic model for chemically-powered Janus motors: Very small synthetic motors that make use of chemical reactions to propel\nthemselves in solution hold promise for new applications in the development of\nnew materials, science and medicine. The prospect of such potential\napplications, along with the fact that systems with many motors or active\nelements display interesting cooperative phenomena of fundamental interest, has\nmade the study of synthetic motors an active research area. Janus motors,\ncomprising catalytic and noncatalytic hemispheres, figure prominently in\nexperimental and theoretical studies of these systems. While continuum models\nof Janus particle systems are often used to describe motor dynamics,\nmicroscopic models that are able to account for intermolecular interactions,\nmany-body concentration gradients, fluid flows and thermal fluctuations provide\na way to explore the dynamical behavior of these complex out-of-equilibrium\nsystems that does not rely on approximations that are often made in continuum\ntheories. The analysis of microscopic models from first principles provides a\nfoundation from which the range of validity and limitations of approximate\ntheories of the dynamics may be assessed. In this paper, a microscopic model\nfor the diffusiophoretic propulsion of Janus motors, where motor interactions\nwith the environment occur only through hard collisions, is constructed,\nanalyzed and compared to theoretical predictions. Microscopic simulations of\nboth single-motor and many-motor systems are carried out to illustrate the\nresults."
    },
    {
        "anchor": "Effect of the adsorption component of the disjoining pressure on foam\n  film drainage: The present work is trying to explain a discrepancy between experimental\nobservations of the drainage of foam films from aqueous solutions of sodium\ndodecyl sulfate (SDS) and the theoretical DLVO-accomplished Reynolds model. It\nis shown that, due to overlap of the film adsorption layers, an adsorption\ncomponent of the disjoining pressure is important for this system. The\npre-exponential factor of the adsorption component was obtained by fitting the\nexperimental drainage curves. It corresponds to a slight repulsion, which\nreduces not only the thinning velocity as observed experimentally but corrects\nalso the film equilibrium thickness.",
        "positive": "Microscopic mechanism for the shear-thickening of non-Brownian\n  suspensions: We propose a simple model, supported by contact-dynamics simulations as well\nas rheology and friction measurements, that links the transition from\ncontinuous to discontinuous shear-thickening in dense granular pastes to\ndistinct lubrication regimes in the particle contacts. We identify a local\nSommerfeld number that determines the transition from Newtonian to\nshear-thickening flows, and then show that the suspension's volume fraction and\nthe boundary lubrication friction coefficient control the nature of the\nshear-thickening transition, both in simulations and experiments."
    },
    {
        "anchor": "Self-propulsion in 2D Confinement: Phoretic and Hydrodynamic\n  Interactions: Chemically active Janus particles generate tangential concentration gradients\nalong their surface for self-propulsion. Although this is well studied in\nunbounded domains, the analysis in biologically relevant environments such as\nconfinements is scarce. In this work, we study the motion of a Janus sphere in\nweak confinement. The particle is placed at an arbitrary location, with an\narbitrary orientation between the two walls. Using the method of reflections,\nwe study the effect of confining planar boundaries on the phoretic and\nhydrodynamic interactions, and their consequence on the Janus particle\ndynamics. The dynamical trajectories are analyzed using phase diagrams for\ndifferent surface coverage of activity and solute-particle interactions. In\naddition to near wall states such as `sliding' and `hovering', we demonstrate\nthat accounting for two planar boundaries reveals two new states:\nchannel-spanning oscillations and damped oscillations around the centerline,\nwhich were characterized as `scattering' or `reflection' by earlier analyses on\nsingle-wall interactions. Using phase diagrams, we highlight the differences in\ninert-facing and active-facing Janus particles. We also compare the dynamics of\nJanus particles with squirmers for contrasting the chemical interactions with\nhydrodynamic effects. Insights from the current work suggest that biological\nand artificial swimmers sense their surroundings through long-ranged\ninteractions, that can be modified by altering the surface properties.",
        "positive": "Collisional regime during the discharge of a 2D silo: The present work reports a novel investigation into the collisional dynamics\nof particles in the vicinity of the outlet of a 2D silo using molecular\ndynamics simulations. Most studies on this granular system focus in the bulk of\nthe medium. In this region contacts are permanent or long-lived, so continuous\napproximations are able to yield results for velocity distributions or mass\nflow. Close to the exit, however, the density of the medium decreases and\ncontacts are instantaneous. Thus, the collisional nature of the dynamics\nbecomes significant, warranting a dedicated investigation as carried out in\nthis work. More interesting, the vicinity of the outlet is the region where the\narches that block the flow for small apertures are formed. It is found that the\ntransition from the clogging regime (at small apertures) to the continuous flow\nregime is smooth in collisional variables. Furthermore, the dynamics of\nparticles as reflected by the distributions of the velocities is as well\nunaffected. This result implies that there is no critical outlet size that\nseparates both regimes, as had been proposed in the literature. Instead, the\nresults achieved support the alternative picture in which a clog is possible\nfor any outlet size."
    },
    {
        "anchor": "Universal Transition to Wide Shear Zones in Entangled Macroscale Chains\n  or Ropes: Macroscale chains have been proposed to give insight into the physics of\nmolecular polymer systems. Nevertheless, understanding the rheological response\nof systems of quasi-one-dimensional semiflexible materials, such as bead-chain\npackings, is currently a great challenge. We study the nonlinear rheology of\nrandom assemblies of macroscale chains -- including steel bead chains and\ncooked spaghetti -- under oscillatory shear. We show that a universal\ntransition from localized to wide shear zones occurs upon increasing the strain\namplitude, for a wide range of lengths, flexibilities, and other structural\nparameters of the constituent elements. The critical strain amplitude coincides\nwith the onset of strain stiffening development in the system. We obtain\nscaling laws for transition sharpness, shear-zone width, and stiffness\nenhancement as a function of chain length. Our findings suggest that the\nentanglements between the constituent elements strengthen when approaching the\ncritical strain amplitude and rapidly become long range, even spanning the\nentire finite system for long enough chains. We show that the nonlinear\nrheological response is governed by the interplay between increasing stored\nelastic forces due to entanglements and increasing contribution of dissipation\nwith shear rate and interlocking between chains.",
        "positive": "Assessing the polymer coil-globule state from the very first spectral\n  modes: The determination of the coil-globule transition of a polymer is generally\nbased on the reconstruction of scaling laws, implying the need for samples from\na rather wide range of different polymer lengths $N$. The spectral point of\nview developed in this work allows for a very parsimonious description of all\nthe aspects of the finite-size coil-globule transition on the basis of the\nfirst two Rouse (cosine) modes only, shedding new light on polymer theory.\nCapturing the relevant configuration path features, the proposed approach\nenables to determine the state of a polymer without the need of any information\nabout the polymer length or interaction strength. Importantly, we propose an\nexperimental implementation of our analysis that can be easily performed with\nmodern fluorescent imaging techniques, and would allow differentiation of coil\nor globule conformations by simply recording the positions of three discernible\nloci on the polymer."
    },
    {
        "anchor": "Stretch formulations and the Poynting effect in nonlinear elasticity: The second invariant of the left Cauchy-Green deformation tensor $\\mathbf{B}$\n(or right $\\mathbf{C}$) has been argued to play a fundamental role in nonlinear\nelasticity. Generalized neo-Hookean materials, which depend only on the first\ninvariant, lead to universal relations that conflict with experimental data,\nfail to display important mechanical behaviors (such as the Poynting effect in\nsimple shear), and may not provide a satisfactory link with the mesoscale.\nHowever, the second invariant term is not a higher order strain contribution to\nthe energy, which lead us to reflect on what is incomplete about neo-Hookean\nmaterials. Instead of the usual Cauchy-Green elastic formulation, we\ninvestigate this matter from the perspective of left stretch $\\mathbf{V}=\n\\sqrt{\\mathbf{B}}$ and Bell strain $\\mathbf{E}_{\\text{Bell}} =\n\\mathbf{V}-\\mathbf{I}$ formulations. Invariants of these tensors offer a\ndifferent interpretation than those of $\\mathbf{B}$ and are linked to different\nclasses of materials. The main example we adopt is a general isotropic energy\nquadratic in Bell strains, the quadratic-Biot material. Despite being quadratic\nin stretch like neo-Hookean, this material presents both the classic and\nreverse Poynting effect in simple shear, whose direction switches as a function\nof the constant conjugate to the second invariant of\n$\\mathbf{E}_{\\text{Bell}}$. Its second normal stress also presents a local\nmaximum as a function of the amount of shear, a transition that is not observed\nin a Mooney-Rivlin solid. Moreover, even the Varga model, linear in Bell\nstrains, presents Poynting in simple shear, which poses the question of why\nthis is not true for a model linear in Green-Lagrange strains. Pure torsion of\na solid cylinder is also discussed, particularly how the behavior of the\nresultant axial force contrasts between the different formulations.",
        "positive": "Avalanche dynamics on a rough inclined plane: Avalanche behavior of gravitationally-forced granular layers on a rough\ninclined plane are investigated experimentally for different materials and for\na variety of grain shapes ranging from spherical beads to highly anisotropic\nparticles with dendritic shape. We measure the front velocity, area and the\nheight of many avalanches and correlate the motion with the area and height. We\nalso measure the avalanche profiles for several example cases. As the shape\nirregularity of the grains is increased, there is a dramatic qualitative change\nin avalanche properties. For rough non-spherical grains, avalanches are faster,\nbigger and overturning in the sense that individual particles have down-slope\nspeeds $u_p$ that exceed the front speed $u_f$ as compared with avalanches of\nspherical glass beads that are quantitatively slower, smaller and where\nparticles always travel slower than the front speed. There is a linear increase\nof three quantities i) dimensionless avalanche height ii) ratio of particle to\nfront speed and iii) the growth rate of avalanche speed with increasing\navalanche size with increasing $\\tan\\theta_r$ where $\\theta_r$ is the bulk\nangle of repose, or with increasing $\\beta_P$, the slope of the depth averaged\nflow rule, where both $\\theta_r$ and $\\beta_P$ reflect the grain shape\nirregularity. These relations provide a tool for predicting important dynamical\nproperties of avalanches as a function of grain shape irregularity. A\nrelatively simple depth-averaged theoretical description captures some\nimportant elements of the avalanche motion, notably the existence of two\nregimes of this motion."
    },
    {
        "anchor": "Segregation and Phase Inversion in a Simple Granular System: The segregation and the phase inversion are investigated through a simple\ngranular system which consists of only two inelastic hard spheres in a square\nbox with an energy source. With the variation of the coefficient of\nrestitution, the mass ratio between two spheres or the box size, we show that\ntwo types of segregated states and crossover between them are realized in such\na small simple system.",
        "positive": "Elastodynamic Transformation Cloaking for Non-Centrosymmetric Gradient\n  Solids: In this paper we investigate the possibility of elastodynamic transformation\ncloaking in bodies made of non-centrosymmetric gradient solids. The goal of\ntransformation cloaking is to hide a hole from elastic disturbances in the\nsense that the mechanical response of a homogeneous and isotropic body with a\nhole covered by a cloak would be identical to that of the corresponding\nhomogeneous and isotropic body outside the cloak. It is known that in the case\nof centrosymmetric gradient solids the balance of angular momentum is the\nobstruction to transformation cloaking. We will show that this is the case for\nnon-centrosymmetric gradient solids as well."
    },
    {
        "anchor": "Shaking-induced motility in suspensions of soft active particles: We investigate theoretically the collective dynamics of soft active particles\nliving in a viscous fluid. We focus on a minimal model for active but\nnon-motile particles consisting of $N>1$ elastic dimers deformed by active\nstresses and interacting hydrodynamically. We first derive a set of effective\nequations of motion for the positions of the particles. We then exploit these\nequations in two experimentally-relevant cases: uncorrelated random internal\nstresses, and uniform monochromatic external shaking. In both cases, we show\nthat small groups of intrinsically non-motile particles can display non-trivial\nmodes of locomotion resulting from the hydrodynamic correlations between the\nparticle-conformation fluctuations. In addition, we demonstrate that a coherent\nshaking yields spatial ordering in suspension of soft particles interacting\nsolely through the fluid.",
        "positive": "Viscoelastic crack propagation: review of theories and applications: We review a theory of crack propagation in viscoelastic solids. We consider\nboth cracks in infinite systems and in finite sized systems. As applications of\nthe theory we consider two adhesion problems, namely pressure sensitive\nadhesives and the ball-flat adhesion problem. We also study crack propagation\nin the pig skin dermis, which is of medical relevance, and rubber wear in the\ncontext of tires."
    },
    {
        "anchor": "Viscoelastic flow transitions in abrupt planar contractions: We present experimental evidence of global viscoelastic flow transitions in\n2:1, 8:1 and 32:1 planar contractions under inertia-less conditions. Light\nsheet visualization and laser Doppler velocimetry techniques are used to probe\nspatial structure and time scales associated with the onset of these\ninstabilities. The results are reported in terms of critical Weissenberg\nnumbers characterizing the fluid flow rates. For a given contraction ratio and\npolymer fluid, a two-dimensional, steady flow with converging streamlines\ntransitions to a two-dimensional pattern with diverging streamlines beyond a\ncritical Weissenberg number. At even higher Weissenberg numbers, spatial\ntransition to three-dimensional flow is observed. A relationship between the\nupstream Weissenberg number for the onset of this spatial instability and the\ncontraction ratio is derived. For contraction ratios substantially greater than\nunity, we observe that further increase in the flow rate results in a second\ntemporal transition to a three-dimensional, time-dependent flow. This complex\nflow arises due to a combination of the effects of stress-curvature interaction\nand three dimensional perturbations induced by the walls bounding the neutral\ndirection. Comparison with studies on other geometries indicates that boundary\nshapes deeply influence the sequence and nature of flow transitions.",
        "positive": "The isotropic-nematic transition for hard rods on a three--dimensional\n  (3D) cubic lattice: Using grand canonical Monte Carlo (GCMC) simulations, we investigate the\nisotropic-nematic phase transition for hard rods of size Lx1x1 on a 3D cubic\nlattice. We observe such a transition for L >= 6. For L = 6, the nematic state\nhas a negative order parameter, reflecting the co--occurrence of two dominating\norientations. For L >= 7, the nematic state has a positive order parameter,\ncorresponding to the dominance of one orientation. We investigate rod lengths\nup to L = 25 and find evidence for a very weakly first-order isotropic-nematic\ntransition, while we cannot completely rule out a second order transition. It\nwas not possible to detect a density jump at the transition, despite using\nlarge systems containing several 10^5 particles. The probability density\ndistributions P(Q) from the GCMC simulations near the transition are very\nbroad, pointing to strong fluctuations. Our results complement earlier results\non the demixing (pseudonematic) transition for an equivalent system in 2D,\nwhich is presumably of Ising--type and is present for L >= 7. We compare our\nresults to lattice fundamental measure theory (FMT) and find that FMT strongly\noverestimates nematic order and consequently predicts a strong first order\ntransition. The rod packing fraction of the nematic coexisting states, however,\nagree reasonably well between FMT and GCMC."
    },
    {
        "anchor": "Effects of Shear-Induced Crystallization on the Rheology and Ageing of\n  Hard Sphere Glasses: The rheological properties of highly concentrated suspensions of hard-sphere\nparticles are studied with particular reference to the rheological response of\nshear induced crystals. Using practically monodisperse hard spheres, we prepare\nshear induced crystals under oscillatory shear and examine their linear and\nnon-linear mechanical response in comparison with their glassy counterparts at\nthe same volume fraction. It is evident, that shear-induced crystallization\ncauses a significant drop in the elastic and viscous moduli due to structural\nrearrangements that ease flow. For the same reason the critical (peak of G'')\nand crossover (overlap of G' and G'') strain are smaller in the crystal\ncompared to the glass at the same volume fraction. When, however the distance\nfrom the maximum packing in each state is taken into account the elastic\nmodulus of the crystal is found to be larger than the glass at the same free\nvolume suggesting a strengthened material due to long range order. Finally,\nshear induced crystals counter-intuitively exhibit similar rheological ageing\nto the glass (with a logarithmic increase of G'), indicating that the shear\ninduced structure is not at thermodynamic equilibrium.",
        "positive": "Stochastic Pore Collapse Models in Granular Materials: Stochastic models for pore collapse in granular materials are developed.\nFirst, a general fluctuating stress-strain relation for a plastic flow rule is\nderived. The fluctuations account for non-associativity in plastic deformations\ntypically observed in heterogeneous materials. Second, an axisymmetric\nspherical shell compaction model is extended to account for fluctuations in the\nmaterial microstructure due to granular interactions at the pore scale. This\nchanges the stress-strain constitutive equation determining the dynamics of\npore collapse. Results show that stochastic differential equations can account\nfor multiscale interactions in a statistical sense."
    },
    {
        "anchor": "Liquid-gas separation in colloidal electrolytes: The liquid-gas transition of an electroneutral mixture of oppositely charged\ncolloids, studied by Monte Carlo simulations, is found in the low temperature\n-- low density region. The critical temperature shows a non-monotonous behavior\nas a function of the interaction range, $\\kappa^{-1}$, with a maximum at\n$\\kappa \\sigma \\approx 10$, implying an island of coexistence in the\n$\\kappa$-$\\rho$ plane. The system is arranged in such a way that each particle\nis surrounded by shells of particles with alternating charge. In contrast with\nthe electrolyte primitive model, both neutral and charged clusters are obtained\nin the vapor phase",
        "positive": "A possible four-phase coexistence in a single-component system: For different phases to coexist in equilibrium at constant temperature $T$\nand pressure $P$, the condition of equal chemical potential $\\mu$ must be\nsatisfied. This condition dictates that, for a single-component system, the\nmaximum number of phases that can coexist is three. Historically this is known\nas the Gibbs phase rule, and is one of the oldest and venerable rules of\nthermodynamics. Here we makes use of the fact that, by varying model\nparameters, the Gibbs phase rule can be generalized so that four phases can\ncoexist even in single-component systems. To systematically search for the\nquadruple point, we use a monoatomic system interacting with a Stillinger-Weber\npotential with variable tetrahedrality. Our study indicates that the quadruple\npoint provides novel flexibility in controlling multiple equilibrium phases and\nmay be realized in systems with tunable interactions, which are nowadays\nfeasible in several soft matter systems (e.g., patchy colloids)."
    },
    {
        "anchor": "Statistical and hydrodynamic properties of topological polymers for\n  various graphs showing enhanced short-range correlation: For various polymers with different topological structures we numerically\nevaluate the mean-square radius of gyration and the hydrodynamic radius\nsystematically through simulation. We call polymers with nontrivial topology\ntopological polymers. We evaluate the two quantities both for ideal and real\nchain models and show that the ratios of the quantities among different\ntopological types do not depend on the existence of excluded volume if the\ntopological polymers have only up to trivalent vertices, as far as the polymers\ninvestigated. We also evaluate the ratio of the gyration radius to the\nhydrodynamic radius, which we expect to be universal from the viewpoint of\nrenormalization group. Furthermore, we show that the short-distance intrachain\ncorrelation is much enhanced for topological polymers expressed with complex\ngraphs.",
        "positive": "Charge-Reversal Instability in Mixed Bilayer Vesicles: Bilayer vesicles form readily from mixtures of charged and neutral\nsurfactants. When such a mixed vesicle binds an oppositely-charged object, its\nmembrane partially demixes: the adhesion zone recruits more charged surfactants\nfrom the rest of the membrane. Given an unlimited supply of adhering objects\none might expect the vesicle to remain attractive until it was completely\ncovered. Contrary to this expectation, we show that a vesicle can instead\nexhibit {\\it adhesion saturation,} partitioning spontaneously into an\nattractive zone with definite area fraction, and a repulsive zone. The latter\nzone rejects additional incoming objects because counterions on the interior of\nthe vesicle migrate there, effectively reversing the membrane's charge. The\neffect is strongest at high surface charge densities, low ionic strength, and\nwith thin, impermeable membranes. Adhesion saturation in such a situation has\nrecently been observed experimentally [H. Aranda-Espinoza {\\it et al.}, {\\sl\nScience} {\\bf285} 394--397 (1999)]."
    },
    {
        "anchor": "Surface evolver simulations of drops on microposts: An important feature in the design of superhydrophobic surfaces is their\nrobustness against collapse from the Cassie-Baxter configuration to the Wenzel\nstate. Upon such a transition a surface loses its properties of low adhesion\nand friction. We describe how to adapt the Surface Evolver algorithm to predict\nthe parameters and mechanism of the collapse transition on posts of arbitrary\nshape. In particular, contributions to the free energy evaluated over the\nsolid-liquid surface are reduced to line integrals to give good convergence.\nThe algorithm is validated for straight, vertical and inclined, posts.\nNumerical results for curved posts with a horizontal section at their ends show\nthat these are more efficient in stabilising the Cassie state than straight\nposts, and identify whether the interface first depins from the post sides or\nthe post tips.",
        "positive": "A new capacitive sensor for displacement measurement in a surface force\n  apparatus: We present a new capacitive sensor for displacement measurement in a Surface\nForces Apparatus (SFA) which allows dynamical measurements in the range of\n0-100 Hz. This sensor measures the relative displacement between two\nmacroscopic opaque surfaces over periods of time ranging from milliseconds to\nin principle an indefinite period, at a very low price and down to atomic\nresolution. It consists of a plane capacitor, a high frequency oscillator, and\na high sensitivity frequency to voltage conversion. We use this sensor to study\nthe nanorheological properties of dodecane confined between glass surfaces."
    },
    {
        "anchor": "Viscous fingering at ultralow interfacial tension: We experimentally study the viscous fingering instability in a fluid-fluid\nphase separated colloid-polymer mixture by means of laser scanning confocal\nmicroscopy and microfluidics. We focus on three aspects of the instability. (i)\nThe interface between the two demixed phases has an ultralow surface tension,\nsuch that we can address the role of thermal interface fluctuations. (ii) We\nimage the interface in three dimensions allowing us to study the interplay\nbetween interface curvature and flow. (iii) The displacing fluid wets all walls\ncompletely, in contrast to traditional viscous fingering experiments, in which\nthe displaced fluid wets the walls. We also perform lattice Boltzmann\nsimulations, which help to interpret the experimental observations.",
        "positive": "Bridgman formula for the thermal conductivity of atomic and molecular\n  liquids: A simple and popular Bridgman's model predicts a linear correlation between\nthe thermal conductivity coefficient and the sound velocity of dense liquids. A\nproportionality coefficient proposed originally is fixed and independent of the\nliquid molecular structure. This work reports a systematic analysis of\ncorrelations between thermal conductivity and sound velocity in simple model\nsystems (hard sphere and Lennard-Jones fluids), monoatomic liquids (argon and\nkrypton), diatomic liquids (nitrogen and oxygen), and several polyatomic\nliquids (water, carbon dioxide, methane, and ethane). It is demonstrated that\nlinear correlations are well reproduced for model fluids as well as real\nmonoatomic and diatomic liquids, but seem less convincing in polyatomic\nmolecular liquids. The coefficient of proportionality is not fixed; it is about\nunity for monoatomic liquids and generally increases with molecular complexity.\nSome implications for the possibility to predict the thermal conductivity\ncoefficients are discussed."
    },
    {
        "anchor": "Density Functional Theory for Block Copolymer Melts and Blends: We derive an expression for the free energy of the blends of block copolymers\nexpressed as a functional of the density distribution of the monomer of each\nblock. The expression is a generalization of the Flory-Huggins-de Gennes theory\nfor homo polymer blends, and also a generalization of the Ohta-Kawasaki theory\nfor the melts of diblock copolymers. The expression can be used for any blends\nof homopolymers and block copolymers of any topological structure. The\nexpression gives a fast and stable computational method to calculate the micro\nand macro phase separation of the blends of homopolymers and block copolymers.",
        "positive": "Anisotropic translational diffusion in the nematic phase: Dynamical\n  signature of the coupling between orientational and translational order in\n  the energy landscape: We find in a model system of thermotropic liquid crystals that the\ntranslational diffusion coefficient parallel to the director $D_{\\parallel}$\nfirst increases and then decreases as temperature drops through the nematic\nphase, and this reversal occurs where the smectic order parameter of the\nunderlying inherent structures becomes significant for the first time. We\nargue, based on an energy landscape analysis, that the coupling between\norientational and translational order can play a role in inducing the\nnon-monotonic temperature behavior of $D_{\\parallel}$. Such a view is likely to\nform the foundation of a theoretical framework to explain the anisotropic\ntranslation diffusion."
    },
    {
        "anchor": "Core-softened water-alcohol mixtures: the solute-size effects: In a recent work [\\textit{J. Mol. Liq}, 2020, \\textbf{320}, 114420], using\nmolecular dynamics simulations and a core-softened potential approach, we have\nshown that adding a simple solute as methanol can \"kill\" the density anomalous\nbehavior as the LLCP is suppressed by the spontaneous crystallization in a\nhexagonal closed packing (HCP) crystal near the LLPT. Now, we extend this work\nin order to realize how longer-chain alcohols will affect the complex behavior\nof water-alcohol mixtures in the supercooled regime. Besides core-softened (CS)\nmethanol, ethanol and 1-propanol were added to a system of identical particles\nthat interact through the continuous shouldered well (CSW) potential. We\nobserved that the density anomaly gradually decreases its extension in phase\ndiagrams until disappearing with the growth of the non-polar chain and the\nalcohol concentration, differently from the liquid-liquid phase transition (and\nthe LLCP), which remained present in all analyzed mixtures, in according to\n\\textit{Nature}, 2001, \\textbf{409}, 692. For our model, the longer non-polar\nchains and higher concentrations gradually impact the competition between the\nscales in the CS potential, leading to a gradual disappearing of the anomalies\nuntil the TMD total disappearance is observed when the first coordination shell\nstructure is also affected: the short-range ordering is favored, leading to\nless competition between short- and long-range ordering and, consequently, to\nthe extinction of anomalies. Also, the non-polar chain size and concentration\nhave an effect on the solid phases, favoring the hexagonal closed packed (HCP)\nsolid and the amorphous solid phase over the body-centered cubic (BCC) crystal.",
        "positive": "Physical mechanisms of the Soret effect in binary Lennard-Jones liquids\n  elucidated with thermal-response calculations: The Soret effect is the tendency of fluid mixtures to exhibit concentration\ngradients in the presence of a temperature gradient. Using molecular-dynamics\nsimulation of two-component Lennard-Jones liquids, it is demonstrated that\nspatially-sinusoidal heat pulses generate both temperature and pressure\ngradients. Over short timescales, the dominant effect is the generation of\ncompressional waves which dissipate over time as the system approaches\nmechanical equilibrium. The approach to mechanical equilibrium is also\ncharacterized by a decrease in particle density in the high-temperature region,\nand an increase in particle density in the low-temperature region. It is\ndemonstrated that concentration gradients develop rapidly during the\npropagation of compressional waves through the liquid. Over longer timescales,\nheat conduction occurs to return the system to thermal equilibrium, with the\nparticle current acting to restore a more uniform particle density. It is shown\nthat the Soret effect arises due to the fact that the two components of the\nfluid exhibit a different response to pressure gradients. First, the so-called\nisotope effect occurs because light atoms tend to respond more rapidly to the\nevolving conditions. In this case, there appears to be a connection to previous\nobservations of fast sound in binary fluids. Second, it is shown that the\npartial pressures of the two components in equilibrium, and more directly the\nrelative magnitudes of their derivatives with respect to temperature and\ndensity, determine which species accumulates in the high- and low-temperature\nregions. In the conditions simulated here, the dependence of the partial\npressure on density gradients is larger than the the dependence on temperature\ngradients."
    },
    {
        "anchor": "Topological Interaction between Loop Structures in Polymer Networks and\n  the Nonlinear Rubber Elasticity: We numerically examine the nonlinear rubber elasticity of topologically\nconstrained polymer networks. We propose a simple and effective model based on\nGraessley and Pearson's topological model (GP model) for describing the\ntopological effect. The main point is to take account of a nonequilibrium\neffect in the synthesis process of the polymer network. We introduce a new\nparameter $\\gamma$ to describe entropic contributions from the entanglement of\npolymer loops, which may be determined from the structural characteristics of\nthe sample. The model is evaluated in the light of experimental data under\nuniaxial and biaxial deformations. As a result, our model exhibits uniaxial\nbehaviors which are common to many elastomers in various deformation regimes\nsuch as Mooney-Rivlin's relation in small extension, stress divergence in the\nelongation limit and the declined stress in compression. Furthermore, it is\nalso qualitatively consistent with biaxial experiments, which can be explained\nby few theoretical models.",
        "positive": "Force propagation in isostatic granular packs: We investigate how forces spread through frictionless granular packs at the\njamming transition. Previous work has indicated that such packs are isostatic,\nand thus obey a null stress law which, independent of the packing history,\ncauses rays of stress to propagate away from a point force at oblique angles.\nPrior verifications of the null stress law have used a sequential packing\nmethod which yields packs with anisotropic packing histories. We create packs\nwithout this anisotropy, and then later break the symmetry by adding a\nboundary. Our isotropic packs are very sensitive, and their responses to point\nforces diverge wildly, indicating that they cannot be described by any\ncontinuum stress model. We stabilize the packs by supplying an additional\nboundary, which makes the response much more regular. The response of the\nstabilized packs resembles what one would expect in a hyperstatic pack, despite\nthe isostatic bulk. The expected stress rays characteristic of null stress\nbehavior are not present. This suggests that isostatic packs do not need to\nobey a null stress condition. We argue that the rays may arise instead from\nmore simple geometric considerations, such as preferred contact angles between\nbeads."
    },
    {
        "anchor": "Click-based porous cationic polymers for enhanced carbon dioxide capture: Imidazolium based porous cationic polymers were synthesized using an\ninnovative and facile approach, which takes advantage of the Debus Radziszewski\nreaction to obtain meso- and microporous polymers following click chemistry\nprinciples. In the obtained set of materials, click based porous cationic\npolymers have the same cationic backbone, whereas they bear the commonly used\nanions of imidazolium poly(ionic liquid)s. These materials show hierarchical\nporosity and a good specific surface area. Furthermore, their chemical\nstructure was extensively characterized using ATR FTIR and SS NMR\nspectroscopies, and HR MS. These polymers show good performance towards carbon\ndioxide sorption, especially those possessing the acetate anion. This polymer\nhas an uptake of 2 mmol per g of CO2 at 1 bar and 273 K, a value which is among\nthe highest recorded for imidazolium poly(ionic liquid)s. These polymers were\nalso modified in order to introduce N-heterocyclic carbenes along the backbone.\nCarbon dioxide loading in the carbene-containing polymer is in the same range\nas that of the non-modified versions, but the nature of the interaction is\nsubstantially different. The combined use of in situ FTIR spectroscopy and\nmicrocalorimetry evidenced a chemisorption phenomenon that brings about the\nformation of an imidazolium carboxylate zwitterion.",
        "positive": "Fast crystallization of rotating membrane proteins: We examine the interactions between actively rotating proteins moving in a\nmembrane. Experimental evidence suggests that such rotor proteins, like the ATP\nsynthases of the inner mitochondrial membrane, can arrange themselves into\nlattices. We show that crystallization is possible through a combination of\nhydrodynamic and repulsive interactions between the rotor proteins. In\nparticular, hydrodynamic interactions induce rotational motion of the rotor\nprotein assembly that, in the presence of repulsion, drives the system into a\nhexagonal lattice. The entire crystal rotates with an angular velocity which\nincreases with motor density and decreases with lattice diameter - larger and\nsparser arrays rotate at a slower pace. The rotational interactions allow\nensembles of proteins to sample configurations and reach an ordered steady\nstate, which are inaccessible to the quenched nonrotational system. Rotational\ninteractions thus act as a sort of temperature that removes disorder, except\nthat actual thermal diffusion leads to expansion and loss of order. In\ncontrast, the rotational interactions are bounded in space. Hence, once an\nordered state is reached, it is maintained at all times."
    },
    {
        "anchor": "Dispersed, condensed and self-limiting states of geometrically\n  frustrated assembly: In self-assembling systems, geometric frustration leads to complex states\ncharacterized by internal gradients of shape misfit. Frustrated assemblies have\ndrawn recent interest due to the unique possibility that their thermodynamics\ncan sense and select the finite size of assembly at length scales much larger\nthan constituent building blocks or their interactions. At present,\nself-limitation is chiefly understood to derive from zero-temperature\nconsiderations, specifically the competition between cohesion and\nscale-dependent elastic costs of frustration. While effects of entropy and\nfinite temperature fluctuations are necessarily significant for self-assembling\nsystems, their impact on the self-limiting states of frustrated assemblies is\nnot known. We introduce a generic, minimal model of frustrated assembly, and\nestablish its finite-temperature and concentration dependent thermodynamics by\nway of simulation and continuum theory. The phase diagram is marked by three\ndistinct states of translation order: a dispersed vapor; a defect-riddled\ncondensate; and the self-limiting aggregate state. We show that, at finite\ntemperature, the self-limiting state is stable at intermediate frustration.\nFurther, in contrast to the prevailing picture, its thermodynamic boundaries\nwith the macroscopic disperse and bulk states are temperature controlled,\npointing to the essential importance of translational and conformational\nentropy in their formation.",
        "positive": "Breakdown of perturbative weak coupling approaches for the biomolecular\n  energy transfer: We show that the biomolecular exciton dynamics under the influence of slow\npolarization fluctuations in the solvent cannot be described by approaches\nwhich are perturbative in the system-bath coupling. For this, we compare\nresults for the decoherence rate of the exciton dynamics of a resumed\nperturbation theory with numerically exact real-time path-integral results. We\nfind up to one order in magnitude difference in the decoherence rate for\nrealistically slow solvent environments even in the weak coupling regime, while\nboth results coincide for fast environmental noise. This shows explicitely the\nnonperturbative influence of the bioenvironmental fluctuations and might render\ncurrent perturbative approaches to biomolecular exciton transport questionable."
    },
    {
        "anchor": "A Machine Learning Inversion Scheme for Determining Interaction from\n  Scattering: We outline a machine learning strategy for determining the effective\ninteraction in the condensed phases of matter using scattering. Via a case\nstudy of colloidal suspensions, we showed that the effective potential can be\nprobabilistically inferred from the scattering spectra without any restriction\nimposed by model assumptions. Comparisons to existing parametric approaches\ndemonstrate the superior performance of this method in accuracy, efficiency,\nand applicability. This method can effectively enable quantification of\ninteraction in highly correlated systems using scattering and diffraction\nexperiments.",
        "positive": "Kinetic mechanisms of crumpled globule formation: Homopolymer chain with beads forming pairwise reversible bonds is a\nwell-known model in polymer physics. We studied kinetics of homopolymer chain\ncollapse, which was induced by pairwise reversible bonds formation. We compared\nkinetic mechanism of this coil-globule transition with the mechanism of\ncollapse in a poor solvent. We discovered, that coil-globule transition occurs\nsufficiently more homogeneously on different scales, if collapse is induced by\npairwise reversible bonds formation. This effect leads to formation of\ntransient structures, which are not similar to the classical pearl-necklace\nconformations formed during collapse in a poor solvent. However, both types of\ncollapse lead to formation of a metastable state of crumpled globule, which is\none of the well-known models of interphase chromatin structure in different\norganisms. Moreover, we found out that stability and dynamics of this state can\nbe controlled by fraction of reversible bonds and bond lifetime."
    },
    {
        "anchor": "Scalings and Limits of Landau-deGennes Models for Liquid Crystals: A\n  Comment on Some Recent Analytical Papers: Some recent analytical papers have explored limiting behaviors of\nLandau-deGennes models for liquid crystals in certain extreme ranges of the\nmodel parameters: limits of \"vanishing elasticity\" (in the language of some of\nthese papers) and \"low-temperature limits.\" We use simple scaling analysis to\nshow that these limits are properly interpreted as limits in which geometric\nlength scales (such as the size of the domain containing the liquid crystal\nmaterial) become large compared to intrinsic length scales (such as correlation\nlengths or coherence lengths, which determine defect core sizes). This\nrepresents the natural passage from a mesoscopic model to a macroscopic model\nand is analogous to a \"London limit\" in the Ginzburg-Landau theory of\nsuperconductivity or a \"large-body limit\" in the Landau-Lifshitz theory of\nferromagnetism. Known relevant length scales in these parameter regimes\n(nematic correlation length, biaxial coherence length) can be seen to emerge\nvia balances in equilibrium Euler-Lagrange equations associated with\nwell-scaled Landau-deGennes free-energy functionals.",
        "positive": "A machine learning assessment of the two states model for lipid bilayer\n  phase transitions: We have adapted a set of classification algorithms, also known as Machine\nLearning, to the identification of fluid and gel domains close to the main\ntransition of dipalmitoyl-phosphatidylcholine (DPPC) bilayers. Using atomistic\nmolecular dynamics conformations in the low and high temperature phases as\nlearning sets, the algorithm was trained to categorize individual lipid\nconfigurations as fluid or gel, in relation with the usual two-states\nphenomenological description of the lipid melting transition. We demonstrate\nthat our machine can learn and sort lipids according to their most likely state\nwithout prior assumption regarding the nature of the order parameter of the\ntransition. Results from our machine learning approach provides strong support\nin favor of a two-states model approach of membrane fluidity."
    },
    {
        "anchor": "Controlled neighbor exchanges drive glassy behavior, intermittency and\n  cell streaming in epithelial tissues: Cell neighbor exchanges are integral to tissue rearrangements in biology,\nincluding development and repair. Often these processes occur via topological\nT1 transitions analogous to those observed in foams, grains and colloids.\nHowever, in contrast to in non-living materials the T1 transitions in\nbiological tissues are rate-limited and cannot occur instantaneously due to the\nfinite time required to remodel complex structures at cell-cell junctions. Here\nwe study how this rate-limiting process affects the mechanics and collective\nbehavior of cells in a tissue by introducing this important biological\nconstraint in a theoretical vertex-based model as an intrinsic single-cell\nproperty. We report in the absence of this time constraint, the tissue\nundergoes a motility-driven glass transition characterized by a sharp increase\nin the intermittency of cell-cell rearrangements. Remarkably, this glass\ntransition disappears as T1 transitions are temporally limited. As a unique\nconsequence of limited rearrangements, we also find that the tissue develops\nspatially correlated streams of fast and slow cells, in which the fast cells\norganize into stream-like patterns with leader-follower interactions, and\nmaintain optimally stable cell-cell contacts. The predictions of this work is\ncompared with existing in-vivo experiments in Drosophila pupal development.",
        "positive": "Programming Active Cohesive Granular Matter with Mechanically Induced\n  Phase Changes: Active matter physics and swarm robotics have provided powerful tools for the\nstudy and control of ensembles driven by internal sources. At the macroscale,\ncontrolling swarms typically utilizes significant memory, processing power, and\ncoordination unavailable at the microscale, e.g., for colloidal robots, which\ncould be useful for fighting disease, fabricating intelligent textiles, and\ndesigning nanocomputers. To develop principles that that can leverage physics\nof interactions and thus can be utilized across scales, we take a two-pronged\napproach: a theoretical abstraction of self-organizing particle systems and an\nexperimental robot system of active cohesive granular matter that intentionally\nlacks digital electronic computation and communication, using minimal (or no)\nsensing and control, to test theoretical predictions. We consider the problems\nof aggregation, dispersion, and collective transport. As predicted by the\ntheory, as a parameter representing interparticle attraction increases, the\nrobots transition from a dispersed phase to an aggregated one, forming a dense,\ncompact collective. When aggregated, the collective can transport non-robot\n\"impurities\" in their environment, thus performing an emergent task driven by\nthe physics underlying the transition. These results point to a fruitful\ninterplay between algorithm design and active matter robophysics that can\nresult in new nonequilibrium physics and principles for programming collectives\nwithout the need for complex algorithms or capabilities."
    },
    {
        "anchor": "Statistical physics of a model binary genetic switch with linear\n  feedback: We study the statistical properties of a simple genetic regulatory network\nthat provides heterogeneity within a population of cells. This network consists\nof a binary genetic switch in which stochastic flipping between the two switch\nstates is mediated by a \"flipping\" enzyme. Feedback between the switch state\nand the flipping rate is provided by a linear feedback mechanism: the flipping\nenzyme is only produced in the on switch state and the switching rate depends\nlinearly on the copy number of the enzyme. This work generalises the model of\n[Phys. Rev. Lett., 101, 118104] to a broader class of linear feedback systems.\nWe present a complete analytical solution for the steady-state statistics of\nthe number of enzyme molecules in the on and off states, for the general case\nwhere the enzyme can mediate flipping in either direction. For this general\ncase we also solve for the flip time distribution, making a connection to first\npassage and persistence problems in statistical physics. We show that the\nstatistics of the model are non-Poissonian, leading to a peak in the flip time\ndistribution. The occurrence of such a peak is analysed as a function of the\nparameter space. We present a new relation between the flip time distributions\nmeasured for two relevant choices of initial condition. We also introduce a new\ncorrelation measure to show that this model can exhibit long-lived temporal\ncorrelations, thus providing a primitive form of cellular memory. Motivated by\nDNA replication as well as by evolutionary mechanisms involving gene\nduplication, we study the case of two switches in the same cell. This results\nin correlations between the two switches; these can either positive or negative\ndepending on the parameter regime.",
        "positive": "Colloidal Motion under the Action of a Thermophoretic Force: We present thermophoretic measurements in aqueous suspensions of three\ndifferent polystyrene (PS) particles of varying negative charge, size and\nsurface coating. Our measurement technique is based on the observation of the\ncolloidal steady-state distribution using conventional bright-field microscopy,\nwhich avoids undesirable effects such as laser-induced convection or local\nheating. We find that the colloids with the weakest zeta potential exhibit the\nstrongest thermophoretic effect, suggesting that surface functionality leads to\na more intricate dependence of the Soret coefficient on hydrodynamic boundary\nconditions than predicted by existing theoretical approaches. We also study the\nrelaxation of the colloids to steady-state and propose a model to quantify the\nrelaxation speed, based on the time evolution of the colloidal center of mass.\nOur observations are well described by this model and show that the relaxation\nspeed tends to increase with the magnitude of the thermophoretic force."
    },
    {
        "anchor": "Numerical study of airborne particle dynamics in vortices subject to\n  electric field: Capture, selective collection and flight manipulation of airborne particulate\nare three important functional requirements in various actively growing aerosol\ntechnology applications. Aerodynamic drag, particle inertia and\ndielectrophoretic (DEP) force due to externally applied electrostatic forces\ninfluence the behavior of micron sized particles significantly, in such\nsituations. In this work, we numerically study how a combination of these\nforces uniquely influences the behavior of uncharged or mildly charged airborne\nparticles, distinct from that with their individual influences. Uncharged\nparticle movements in a numerically fabricated well structured steady vortical\nflow between two curved electrode surfaces are analyzed. Vortical air\ncirculation towards and away from the electrode tip enhances and deteriorates\nelectrostatic particulate capture on the electrodes, termed as co and counter\ndirections with respect to the electrostatic force on particles respectively.\nParticles in counter vortices under an electric field reveals a rich variety of\nunique behaviors due to the interplay of drag, inertia and DEP forces.\nDistortion of the vortex structure due to convexity of electrode surfaces\nresults in an inverse inertial limit cycle trajectory trapping of particles;\nwith the airborne particles spatially segregated, trapping larger particles\nfurther inside the vortex than the smaller particles.Value of a dimensionless\nnumber $\\xi_v$, the ratio of DEP force and particle inertia, represents the\ncombination of the operating flow and electric field strengths. Inertial\ncut-off of particle capture in this configuration abruptly shift to DEP capture\nat a critical value of $\\xi_v\\approx 0.2$, as its value increases. Selective\ndeposition of particles within a closed range of size and density, emerges due\nto the interplay of vortex trapping, inertial expulsion and electrostatic\ncapture.",
        "positive": "Programmable phase behavior in fluids with designable interactions: We introduce a method for solving the \"inverse\" phase equilibria problem: How\nshould the interactions among a collection of molecular species be designed in\norder to achieve a target phase diagram? Using techniques from convex\noptimization theory, we show how to solve this problem for phase diagrams\ncontaining a large number of components and many coexisting phases with\nprescribed compositions. We apply our approach to commonly used mean-field\nmodels of multicomponent fluids and then use molecular simulations to verify\nthat the designed interactions result in the target phase diagrams. Our\napproach enables the rational design of \"programmable\" fluids, such as\nbiopolymer and colloidal mixtures, with complex phase behavior."
    },
    {
        "anchor": "Carnahan Starling type equations of state for stable hard disk and hard\n  sphere fluids: The well-known Carnahan-Starling (CS) equation of state (EoS) [1] for the\nhard sphere (HS) fluid was derived from a quadratic relation between the\ninteger portions of the virial coefficients, Bn, and their orders, n. Here we\nextend the method to the full virial coefficients Bn for the general\nD-dimensional case. We assume a polynomial function of (D-1)th order for the\nvirial coefficients starting from n=4 and EoS are derived from it. For the hard\nrob (D=1) case, the exact solution is obtained. For the stable hard disk fluid\n(D=2), the most recent virial coefficients up to the 10th [2] and accurate\ncompressibility data[3,4] are employed to construct and test the EoS. For the\nstable hard sphere (D=3) fluid, a new CS-type EoS is constructed and tested\nwith the most recent virial coefficients [5,2] up to the 11th and with the\nhighly-accurate simulation data for compressibility [6-8]. The simple new EoS\nturn out to be as accurate as the highest-level Pade approximations based on\nall available virial coefficients, and significantly improve the CS-type EoS in\nthe hard sphere case. We also shown that as long as the virial coefficients\nobey a polynomial function any EoS derived from it will diverge at the\nnon-physical packing fraction=1.",
        "positive": "L\u00e9vy Walks and Path Chaos in the Dispersal of Elongated Structures\n  Moving across Cellular Vortical Flows: In cellular vortical flows, namely arrays of counter-rotating vortices, short\nbut flexible filaments can show simple random walks through their stretch-coil\ninteractions with flow stagnation points. Here, we study the dynamics of\nsemi-rigid filaments long enough to broadly sample the vortical field. Using\nsimulation, we find a surprising variety of long-time transport behavior --\nrandom walks, ballistic transport, and trapping -- depending upon the\nfilament's relative length and effective flexibility. Moreover, we find that\nfilaments execute L\\'evy walks whose diffusion exponents generally decrease\nwith increasing filament length, until transitioning to Brownian walks.\nLyapunov exponents likewise increase with length. Even completely rigid\nfilaments, whose dynamics is finite-dimensional, show a surprising variety of\ntransport states and chaos. Fast filament dispersal is related to an underlying\ngeometry of ``conveyor belts''. Evidence for these various transport states are\nfound in experiments using arrays of counter-rotating rollers, immersed in a\nfluid and transporting a flexible ribbon."
    },
    {
        "anchor": "Translocation of Polymers through Nanopores at Weak External Field,\n  Direct Approach with Monte Carlo Simulations: I did off-lattice 3D Monte Carlo simulations for polymer translocation\nthrough a narrow pore at low external field, trying to be as close to a direct\napproach as possible. The process was found non equilibrium globally, but\ndynamics of the monomers close to the pore (the fold) was found close to quasi\nequilibrium. I observed a tension (or pressure) buildup near the pore, and\nsubdiffusion for the displacement of the middle monomer in the pore, as\nreported in the literature. I did not find the distribution of the reaction\ncoordinate after some time of free diffusion predicted by the fractional\ndiffusion equation.",
        "positive": "Hydrodynamic Manipulation of Nano-Objects by Thermo-Osmotic Flows: The manipulation of micro- and nano-objects is of great technological\nsignificance to construct new materials, manipulate tiny amounts of liquids in\nfluidic systems, or detect minute concentrations of analytes. It is commonly\napproached by the generation of potential energy landscapes, for example, with\noptical fields. Here we show that strong hydrodynamic boundary flows enable the\ntrapping and manipulation of nano-objects near surfaces. These thermo-osmotic\nflows are induced by modulating the van der Waals interaction at a solid-liquid\ninterface with optically induced temperature fields. We use a thin gold film on\na glass substrate to provide localized but reconfigurable point-like optical\nheating. Convergent boundary flows with velocities of tens of micrometres per\nsecond are observed and substantiated by a quantitative physical model. The\nhydrodynamic forces acting on suspended nanoparticles and attractive van der\nWaals or depletion induced forces to enable precise positioning and guiding of\nthe nanoparticles. Fast multiplexing of flow fields further provides the means\nfor parallel manipulation of many nano-objects. Our findings have direct\nconsequences for the field of plasmonic nano-tweezers and other\nthermo-plasmonic trapping schemes and pave the way for a general scheme of\nnanoscopic manipulation with boundary flows."
    },
    {
        "anchor": "Cell Model Approaches for Predicting the Swelling and Mechanical\n  Properties of Polyelectrolyte Gels: We present two successive mean-field approximations for describing the\nmechanical properties and the swelling equilibrium of polyelectrolyte gels in\ncontact with a salt solution. The first mean-field approximation reduces the\nmany-chain problem of a gel to a corresponding single chain problem. The second\nmean-field step integrates out the degrees of freedom of the flexible chain and\nthe ions. It replaces the particle-based description of the polyelectrolyte\nwith suitable charge distributions and an effective elasticity term. These\nsimplifications result in a computationally very efficient Poisson-Boltzmann\ncell-gel description. Despite their simplicity, the single chain cell-gel model\nshows excellent and the PB model very good agreement with explicit molecular\ndynamics simulations of the reference periodic monodisperse network model for\nvarying chain length, polymer charge fraction, and external reservoir salt\nconcentrations. Comparisons of our models to the Katchalsky model reveal that\nour approach is superior for strongly charged chains and can also predict the\nbulk moduli more accurately. We further discuss chain length polydispersity\neffects, investigate changes in the solvent permittivity, and demonstrate the\nrobustness of our approach to parameter variations coming from several modeling\nassumptions.",
        "positive": "Experimental Measurement of the Persistence Exponent of the Planar Ising\n  Model: Using a twisted nematic liquid crystal system exhibiting planar Ising model\ndynamics, we have measured the scaling exponent $\\theta$ which characterizes\nthe time evolution, $p(t) \\sim t^{-\\theta}$, of the probability p(t) that the\nlocal order parameter has not switched its state by the time t. For 0.4 seconds\nto 200 seconds following the phase quench, the system exhibits scaling behavior\nand, measured over this interval, $\\theta = 0.19 \\pm 0.031$, in good agreement\nwith theoretical analysis and numerical simulations."
    },
    {
        "anchor": "Self-transport of swimming bacteria is impaired by porous microstructure: Motility is a fundamental survival strategy of bacteria to navigate porous\nenvironments. Swimming cells thrive in quiescent wetlands and sediments at the\nbottom of the marine water column, where they mediate many essential\nbiogeochemical processes. While swimming motility in bulk fluid is now well\nestablished, a comprehensive understanding of the mechanisms regulating\nself-transport in the confined interstices of porous media is lacking, and\ndetermining the interactions between cells and surfaces of the solid matrix\nbecomes paramount. Here, we precisely track the movement of bacteria\n(\\emph{Magnetococcus marinus}) through a series of microfluidic porous media\nwith broadly varying geometries and show that cell motility results in a\nsuccession of scattering events from the porous microstructure. Order or\ndisorder can impact the cells' motility over short ranges, but we directly\ndemonstrate that their large-scale transport properties are regulated by the\ncutoff of their persistent swimming, which is dictated primarily by the\nporosity and scale of the porous geometry. The effective mean free path is\nestablished as the key geometrical parameter controlling transport, and along\nwith with minimal knowledge of cell swimming motility and surface scattering\nproperties, we implement a theoretical model that universally predicts the\neffective diffusion of cells for the geometries studied here. These results are\nan important step toward predicting the physical ecology of swimming cells in\nquiescent porous media and understanding their role in environmental and health\nhazards in stagnant water.",
        "positive": "Mean-Field Analysis of the Glassy Dynamics of an Elastoplastic Model of\n  Super-Cooled Liquids: We present a mean-field theory of a coarse-grained model of a super-cooled\nliquid in which relaxation occurs via local plastic rearrangements. Local\nrelaxation can be induced by thermal fluctuations or by the long-range elastic\nconsequences of other rearrangements. We extract the temperature dependence of\nboth the relaxation time and the lengthscale of dynamical correlations. We find\ntwo dynamical regimes. First, a regime in which the characteristic time and\nlength scales diverge as a power law at a critical temperature $T_c$. This\nregime is found by an approximation that neglects activated relaxation\nchannels, which can be interpreted as akin to the one found by the\nmode-coupling transition of glasses. In reality, only a cross-over takes place\nat $T_c$. The residual plastic activity leads to a second regime characterised\nby an Arrhenius law below $T_c$. In this case, we show that the lengthscale\ngoverning dynamical correlations diverges as a power law as $T\\to 0$, and is\nlogarithmically related to the relaxation time."
    },
    {
        "anchor": "Three-dimensional acoustic lensing with a bubbly diamond metamaterial: A sound wave travelling in water is scattered by a periodic assembly of air\nbubbles. The local structure matters even in the low frequency regime. If the\nbubbles are arranged in a face-centered cubic (fcc) lattice, a total band gap\nopens near the Minnaert resonance frequency. If they are arranged in the\ndiamond structure, which one obtains by simply adding a second bubble to the\nunit cell, one finds an additional branch with a negative slope (optical\nbranch). For a single specific frequency, the medium behaves as if its\nrefractive index (relative to water) is exactly $n=-1$. We show that a slab of\nthis material can be used to design a three three-dimensional flat lens. We\nalso report super-resolution focusing in the near field of the slab and\nillustrate its potential for imaging in three dimensions.",
        "positive": "Dynamical heterogeneities in non-entangled polystyrene and poly(ethylene\n  oxide) star melts: Star polymers can exhibit a heterogeneous dynamical behavior due to their\ninternal structure. In this work we employ atomistic molecular dynamics\nsimulations to study translational motion in non-entangled polystyrene and\npoly(ethylene oxide) star-shaped melts. We focus on the local heterogeneous\ndynamics originating from the multi-arm star-like architecture and quantify the\nintramolecular dynamical gradient. By examining the translational motion at\nlength scales of the order of the Kuhn length, we aim to find common features\nfor both studied chemistries and to provide a critical and direct comparison\nwith theoretical models of polymer dynamics. We discuss the observed tendencies\nwith respect to the continuous Rouse model adjusted for the star-like\narchitectures. Two versions of the Rouse model are examined: one assuming\nuniform friction on every Rouse bead and another one considering larger branch\npoint friction. Apart from chain connectivity between neighboring beads, both\nversions disregard interactions between the chains. Despite the tolerable\ndescription of the simulation data, neither model appears to reflect the\nmobility gradient accurately. The detailed quantitative atomistic models\nemployed here bridge the gap between the theoretical and general,\ncoarse-granined models of star-like polymers which lack the indispensable\nchemical details."
    },
    {
        "anchor": "DNA Confined in Nanochannels: Hairpin Tightening by Entropic Depletion: A theory is presented of DNA hairpins enclosed in a nanochannel. A hairpin\nbecomes constrained as it approaches the wall of a channel which leads to an\nentropic force causing the hairpin to tighten. The free energy of the hairpin\ncomputed in the classical limit is significantly larger than what one would\nexpect. As a result, the distance between hairpins or the global persistence\nlength is often tens of micrometers long and may even reach mm sizes for 10 nm\nthin channels. The hairpin shape and size, and the DNA elongation are computed\nfor nanoslits, and circular and square nanoschannels. A comparison with\nexperiment is given.",
        "positive": "Ab initio molecular dynamics study of dissociation of water under an\n  electric field: The behavior of liquid water under an electric field is a crucial phenomenon\nin science and engineering. However, its detailed description at a microscopic\nlevel is difficult to achieve experimentally. Here we report on the first ab\ninitio molecular-dynamics study on water under an electric field. We observe\nthat the hydrogen-bond length and the molecular orientation are significantly\nmodified at low-to-moderate field intensities. Fields beyond a threshold of\nabout 0.35 V/\\AA are able to dissociate molecules and sustain an ionic current\nvia a series of correlated proton jumps. Upon applying even more intense fields\n(1.0 V/\\AA), a 15-20% fraction of molecules are instantaneously dissociated and\nthe resulting ionic flow yields a conductance of about 7.8\n$\\Omega^{-1}cm^{-1}$, in good agreement with experimental values. This result\npaves the way to quantum-accurate microscopic studies of the effect of electric\nfields on aqueous solutions and, thus, to massive applications of ab initio\nmolecular dynamics in neurobiology, electrochemistry and hydrogen economy."
    },
    {
        "anchor": "Optimal escapes in active matter: The out-of-equilibrium character of active particles, responsible for\naccumulation at boundaries in confining domains, determines not-trivial effects\nwhen considering escape processes. Non-monotonous behavior of exit times with\nrespect to tumbling rate (inverse of mean persistent time) appears, as a\nconsequence of the competing processes of exploring the bulk and accumulate at\nboundaries. By using both 1D analytical results and 2D numerical simulations of\nrun-and-tumble particles with different behaviours at boundaries, we scrutinize\nthis very general phenomenon of active matter, evidencing the role of\naccumulation at walls for the existence of optimal tumbling rates for fast\nescapes.",
        "positive": "Printing on particles: combining two-photon nanolithography and\n  capillary assembly to fabricate multi-material microstructures: Additive manufacturing at the micro- and nanoscale has seen a recent upsurge\nto suit the increasing demand for more elaborate structures. However, the\nintegration and precise placement of multiple distinct materials at small\nscales remain a challenge. To this end, we combine here the directed capillary\nassembly of colloidal particles and two-photon direct laser writing (DLW) to\nrealize a new class of multi-material microstructures. We use DLW both to\nfabricate 3D micro-templates to guide the capillary assembly of soft- and hard\ncolloids, and to link well-defined arrangements of polystyrene or silica\nparticles produced with capillary assembly, a process we term \"printing on\nparticles\". The printing process is based on automated particle recognition\nalgorithms and enables the user to connect colloids into one- and\ntwo-dimensional tailored structures, including particle clusters and lattices\nof varying symmetry and composition, using commercial photo-resists (IP-L or\nIP-PDMS). Once printed and developed, the structures can be easily harvested\nand re-dispersed in water. The flexibility of our method allows the combination\nof a wide range of materials into complex structures, which we envisage will\nboost the realization of new systems for a broad range of fields, including\nmicrorobotics, micromanipulation and metamaterials."
    },
    {
        "anchor": "Learning about SANS Instruments and Data Reduction from Round Robin\n  Measurements on Samples of Polystyrene Latex: Measurements of a well-characterised standard sample can verify the\nperformance of an instrument. Typically, small-angle neutron scattering\ninstruments are used to investigate a wide range of samples and may often be\nused in a number of configurations. Appropriate standard samples are useful to\ntest different aspects of the performance of hardware as well as that of the\ndata reduction and analysis software. Measurements on a number of instruments\nwith different intrinsic characteristics and designs in a round robin can not\nonly better characterise the performance for a wider range of conditions but\nalso, perhaps more importantly, reveal the limits of the current state of the\nart of small-angle scattering. The exercise, followed by detailed analysis,\ntests the limits of current understanding as well as uncovers often forgotten\nassumptions, simplifications and approximations that underpin the current\npractice of the technique. This paper describes measurements of polystyrene\nlatex, radius 72 nm with a number of instruments. Scattering from monodisperse,\nuniform spherical particles is simple to calculate and displays sharp minima.\nSuch data test the calibrations of intensity, wavelength and resolution as well\nas the detector response. Smoothing due to resolution, multiple scattering and\npolydispersity has been determined. Sources of uncertainty are often related to\nsystematic deviations and calibrations rather than random counting errors. The\nstudy has prompted development of software to treat modest multiple scattering\nand to better model the instrument resolution. These measurements also allow\nchecks of data reduction algorithms and have identified how they can be\nimproved. The reproducibility and the reliability of instruments and the\naccuracy of parameters derived from the data are described.",
        "positive": "Excluded volume effects on the structure of a linear polymer under shear\n  flow: The effect of excluded volume interactions on the structure of a polymer in\nshear flow is investigated by Brownian Dynamics simulations for chains with\nsize $30\\leq N\\leq 300$. The main results concern the structure factor $S({\\bf\nq})$ of chains of N=300 Kuhn segments, observed at a reduced shear rate\n$\\beta=\\dot{\\gamma}\\tau=3.2$, where $\\dot{\\gamma}$ is the bare shear rate and\n$\\tau$ is the longest relaxation time of the chain. At low q, where anisotropic\nglobal deformation is probed, the chain form factor is shown to match the form\nfactor of the continuous Rouse model under shear at the same reduced shear\nrate, computed here for the first time in a wide range of wave vectors. At high\nq, the chain structure factor evolves towards the isotropic equilibrium power\nlaw $q^{-1/\\nu}$ typical of self-avoiding walk statistics. The matching between\nexcluded volume and ideal chains at small q, and the excluded volume power law\nbehavior at large q are observed for ${\\bf q}$ orthogonal to the main\nelongation axis but not yet for ${\\bf q}$ along the elongation direction\nitself, as a result of interferences with finite extensibility effects. Our\nsimulations support the existence of anisotropic shear blobs for polymers in\ngood solvent under shear flow for $\\beta>1$ provided chains are sufficiently\nlong."
    },
    {
        "anchor": "Phase separation and nucleation in mixtures of particles with different\n  temperatures: Differences in activities in colloidal particles are sufficient to drive\nphase separation between active and passive (or less active) particles, even if\nthey have only excluded volume interactions. In this paper, we study the phase\nseparation kinetics and propose a theory of phase separation of colloidal\nmixtures in the diffusive limit. Our model considers a mixture of diffusing\nparticles coupled to different thermostats, it thus has a non-equilibrium\nnature due to the temperature differences. However, we show that indeed the\nsystem recovers an effective equilibrium thermodynamics in the dilute limit. We\nobtain phase diagrams showing the asymmetry in concentrations due to activity\ndifferences. By using a more general approach, we show the equivalence of phase\nseparation kinetics with the well known Cahn-Hilliard theory. On the other\nhand, higher order expansions in concentration indicate the emergence of\nnon-equilibrium effects leading to a breakdown of the equilibrium analogy. We\nlay out the general theory in terms of accessible parameters which we\ndemonstrate by several applications. In this simple formalism, we capture a\npositive surface tension for hard spheres}, and interesting scaling laws for\ninterfacial properties, droplet growth dynamics, and phase segregation\nconditions. \\rev{Several of our results are in agreement with existing\nnumerical simulations while we also propose testable predictions.",
        "positive": "Statistical Mechanics of Integral Membrane Protein Assembly: During the synthesis of integral membrane proteins (IMPs), the hydrophobic\namino acids of the polypeptide sequence are partitioned mostly into the\nmembrane interior and hydrophilic amino acids mostly into the aqueous exterior.\nWe analyze the minimum free energy state of polypeptide sequences partitioned\ninto alpha-helical transmembrane (TM) segments and the role of thermal\nfluctuations using a many-body statistical mechanics model. Results suggest\nthat IMP TM segment partitioning shares important features with general\ntheories of protein folding. For random polypeptide sequences, the minimum free\nenergy state at room temperature is characterized by fluctuations in the number\nof TM segments with very long relaxation times. Simple assembly scenarios do\nnot produce a unique number of TM segments and jamming phenomena interfere with\nsegment placement. For sequences corresponding to IMPs, the minimum free energy\nstructure with the wildtype number of segments is free of number fluctuations\ndue to an anomalous gap in the energy spectrum, and simple assembly scenarios\nproduce this structure. There is a threshold number of random point mutations\nbeyond which the size of this gap is reduced so that the wildtype groundstate\nis destabilized and number fluctuations reappear."
    },
    {
        "anchor": "Solving the Classical Nucleation Theory with respect to the surface\n  energy: An essential parameter of the Classical Nucleation Theory (CNT) is the\nsurface energy between a critical-size nucleus and the ambient phase, $\\sigma$.\nIn condensed matter, this parameter cannot be experimentally determined\nindependently of CNT. A common practice to obtain $\\sigma$ is to assume a model\nfor its temperature-dependence and perform a regression of the CNT equation\nagainst experimental nucleation data. The drawback of this practice is that\nassuming the temperature-dependence of $\\sigma$ adds a bias to the analysis.\nNonetheless, this practice is common because an analytical solution of the\nClassical Nucleation Theory with respect to $\\sigma$ is not possible\nconsidering common expressions of this theory. In this article, a general\nnumerical solution to this problem using the Lambert $W$ function is proposed,\ntested, and compared with typical regression methods. The major advantage of\nthe proposed method is that there is no need to assume a model for the\ntemperature-dependence of $\\sigma$.",
        "positive": "Interaction of Proteins with Polyelectrolytes: A Comparison between\n  Theory and Experiment: We discuss recent investigations of the interaction of polyelectrolytes with\nproteins. In particular, we review our recent studies on the interaction of\nsimple proteins such as human serum albumin (HSA) or lysozyme with linear\npolyelectrolytes, charged dendrimers, charged networks, and polyelectrolyte\nbrushes. In all cases discussed here we combined experimental work with\nmolecular dynamics (MD) simulations and mean-field theories. In particular,\nisothermal titration calorimetry (ITC) has been employed to obtain the\nrespective binding constants Kb and the Gibbs free energy of binding.\nMD-simulations with explicit counterions but implicit water demonstrate that\ncounterion release is the main driving force for the binding of proteins to\nstrongly charged polyelectrolytes: Patches of positive charges located on the\nsurface of the protein become a multivalent counterion of the polyelectrolyte\nthereby releasing a number of counterions condensed on the polyelectrolyte. The\nbinding Gibbs free energy due to counterion release is predicted to scale with\nthe logarithm of the salt concentration in the system which is verified both by\nsimulations and experiment. In several cases, namely for the interaction of\nproteins with linear polyelectrolytes and highly charged hydrophilic dendrimers\nthe binding constant could be calculated from simulations in very good\napproximation. This finding demonstrated that in these cases explicit hydration\neffects do not contribute to the Gibbs free energy of binding. The Gibbs free\nenergy can also be used to predict the kinetics of protein uptake by microgels\nfor a given system by applying dynamic density functional theory."
    },
    {
        "anchor": "The Role of Architecture in the Elastic Response of Semiflexible Polymer\n  and Fiber Networks: We study the elasticity of cross-linked networks of thermally fluctuating\nstiff polymers. As compared to their purely mechanical counterparts, it is\nshown that these thermal networks have a qualitatively different elastic\nresponse. By accounting for the entropic origin of the single-polymer\nelasticity, the networks acquire a strong susceptibility to polydispersity and\nstructural randomness that is completely absent in athermal models. In\nextensive numerical studies we systematically vary the architecture of the\nnetworks and identify a wealth of phenomena that clearly show the strong\ndependence of the emergent macroscopic moduli on the underlying mesoscopic\nnetwork structure. In particular, we highlight the importance of the full\npolymer length that to a large extent controls the elastic response of the\nnetwork, surprisingly, even in parameter regions where it does not enter the\nmacroscopic moduli explicitly. We provide theoretical scaling arguments to\nrelate the observed macroscopic elasticity to the physical mechanisms on the\nmicroscopic and the mesoscopic scale.",
        "positive": "Identification of structural relaxation in the dielectric response of\n  water: One century ago pioneering dielectric results obtained for water and\nn-alcohols triggered the advent of molecular rotation diffusion theory\nconsidered by Debye to describe the primary dielectric absorption in these\nliquids. Comparing dielectric, viscoelastic, and light scattering results we\nunambiguously demonstrate that the structural relaxation appears only as a\nhigh-frequency shoulder in the dielectric spectra of water. In contrast, the\nmain dielectric peak is related to a supramolecular structure, analogous to the\nDebye-like peak observed in mono-alcohols."
    },
    {
        "anchor": "Topological mechanics of gyroscopic metamaterials: Topological mechanical metamaterials are artificial structures whose unusual\nproperties are protected very much like their electronic and optical\ncounterparts. Here, we present an experimental and theoretical study of an\nactive metamaterial -- comprised of coupled gyroscopes on a lattice -- that\nbreaks time-reversal symmetry. The vibrational spectrum of these novel\nstructures displays a sonic gap populated by topologically protected edge modes\nwhich propagate in only one direction and are unaffected by disorder. We\npresent a mathematical model that explains how the edge mode chirality can be\nswitched via controlled distortions of the underlying lattice. This effect\nallows the direction of the edge current to be determined on demand. We\nenvision applications of these edges modes to the design of loss-free, one-way,\nacoustic waveguides and demonstrate this functionality in experiment.",
        "positive": "Entropically-induced asymmetric passage times of charged tracers across\n  corrugated channels: We analyze the diffusion of charged and neutral tracers suspended in an\nelectrolyte embedded in a channel of varying cross-section. Making use of\nsystematic approximations, the diffusion equation governing the motion of\ntracers is mapped into an effective $1D$ equation describing the dynamics along\nthe longitudinal axis of the channel where its varying-section is encoded as an\neffective entropic potential. This simplified approach allows us to\ncharacterize tracer diffusion under generic confinement by measuring their mean\nfirst passage time (MFPT). In particular, we show that the interplay between\ngeometrical confinement and electrostatic interactions strongly affect the MFTP\nof tracers across corrugated channels hence leading to alternative means to\ncontrol tracers translocation across charged pores. Finally, our results show\nthat the MFPTs of a charged tracer in opposite directions along an asymmetric\nchannel may differ. We expect our results to be relevant for biological as well\nsynthetic devices whose dynamics is controlled by the detection of diluted\ntracers."
    },
    {
        "anchor": "Stress overshoot, hysteresis and Bauschinger effect in sheared dense\n  colloidal suspensions: The mechanical non-linear response of dense Brownian suspensions of polymer\ngel particles is studied experimentally and by means of numerical simulations.\nIt is shown that the response to the application of a constant shear rate\ndepends on the previous history of the suspension. When the flow starts from a\nsuspension at rest, it exhibits an elastic response followed by a stress\novershoot and then a plastic flow regime. Conversely, after flow reversal, the\nstress overshoot does not occur, and the apparent elastic modulus is reduced\nwhile numerical simulations reveal that the anisotropy of the local\nmicrostructure is delayed relative to the macroscopic stress.",
        "positive": "Random lasing in a solution of reflective colloidal particles: the\n  effect of interfaces and inter-particle correlations: The propagation of light across 2D and 3D slabs of reflective colloidal\nparticles in a fluid-like state has been investigated by simulation. The\ncolloids are represented as hard spheres with and without an attractive\nsquare-well tail. Representative configurations of particles have been\ngenerated by Monte Carlo. The path of rays entering the slab normal to its\nplanar surface has been determined by exact geometric scattering conditions,\nassuming that particles are macroscopic spheres fully reflective at the surface\nof their hard-core potential. The analysis of light paths provides the\ntransmission and reflection coefficients, the mean-free path, the average\nlength of transmitted and reflected paths, the distribution of scattering\nevents across the slab, and the angular spread of the outcoming rays as a\nfunction of dimensionality and thermodynamic state. The results highlight the\npresence of a sizeable population of very long paths, which play an important\nrole in random lasing from solutions of metal particles in an optically active\nfluid. The output power spectrum resulting from the stimulated emission\namplification decays asymptotically as an inverse power law. The present study\ngoes beyond the standard approach based on a random walk confined between two\nplanar interfaces and parametrised in terms of the mean-free path and\nscattering matrix. Here, instead, the mean free path, the correlation among\nscattering events, and memory effects are not assumed a priori but emerge from\nthe underlying statistical mechanics model of interacting particles. Moreover,\nthe approach joins smoothly the ballistic regime of light propagation at low\ndensity with the diffusive regime at high density of scattering centres. These\nproperties are exploited to investigate the effect of weak polydispersivity and\nof large density fluctuations at the critical point of the model with the\nattractive potential tail."
    },
    {
        "anchor": "How important are fluctuations in the treatment of internal friction in\n  polymers?: The Rouse model with internal friction (RIF), a widely used theoretical\nframework to interpret the effects of internal friction on conformational\ntransitions in biomolecules, is shown to be an approximate treatment that is\nbased on preaveraging internal friction. By comparison with Brownian dynamics\nsimulations of an exact coarse-grained model that incorporates fluctuations in\ninternal friction, the accuracy of the preaveraged model predictions is\nexamined both at and away from equilibrium. While the two models predict\nintrachain autocorrelations that approach each other for long enough chain\nsegments, they differ in their predictions for shorter segments. Furthermore,\nthe two models differ qualitatively in their predictions for the chain\nextension and viscosity in shear flow, which is taken to represent a\nprototypical out-of-equilibrium condition.",
        "positive": "Coarse-grained computations of demixing in dense gas-fluidized beds: We use an \"equation-free\", coarse-grained computational approach to\naccelerate molecular dynamics-based computations of demixing (segregation) of\ndissimilar particles subject to an upward gas flow (gas-fluidized beds). We\nexplore the coarse-grained dynamics of these phenomena in gently fluidized beds\nof solid mixtures of different densities, typically a slow process for which\nreasonable continuum models are currently unavailable."
    },
    {
        "anchor": "Minimal descriptions of cyclic memories: Many materials that are out of equilibrium can \"learn\" one or more inputs\nthat are repeatedly applied. Yet, a common framework for understanding such\nmemories is lacking. Here we construct minimal representations of cyclic memory\nbehaviors as directed graphs, and we construct simple physically-motivated\nmodels that produce the same graph structures. We show how a model of worn\ngrass between park benches can produce multiple transient memories---a behavior\npreviously observed in dilute suspensions of particles and charge-density-wave\nconductors---and the Mullins effect. Isolating these behaviors in our simple\nmodel allows us to assess the necessary ingredients for these kinds of memory,\nand to quantify memory capacity. We contrast these behaviors with a simple\nPreisach model that produces return-point memory. Our analysis provides a\nunified method for comparing and diagnosing cyclic memory behaviors across\ndifferent materials.",
        "positive": "Topological defects govern crack front motion and facet formation on\n  broken surfaces: Patterns on broken surfaces are well-known from everyday experience, but\nsurprisingly, how and why they form are very much open questions. Well-defined\nfacets are commonly observed1-4 along fracture surfaces which are created by\nslow tensile cracks. As facets appear in amorphous materials5-7, their\nformation does not reflect microscopic order. Fracture mechanics, however,\npredict that slow crack fronts should be straight, creating mirror-like\nsurfaces8-13. In contrast, facet-forming fronts propagate simultaneously within\ndifferent planes separated by steps. It is therefore unclear why steps are\nstable, what determines their path and how they couple to crack front dynamics.\nHere we show, by integrating real-time imaging of propagating crack fronts with\nsurface measurements, that steps are topological defects of crack fronts; crack\nfront separation into discontinuous overlapping segments provides the condition\nfor step stability. Steps drift at a constant angle to the local front\npropagation direction and the increased local dissipation due to step formation\ncouples to the long-range deformation of the surrounding crack fronts. Slow\ncrack front dynamics are enslaved to changes in step heights and positions.\nThese observations show how 3D topology couples to 2D fracture dynamics to\nprovide a fundamental picture of how patterned surfaces are generated."
    },
    {
        "anchor": "Residual stresses and shear-induced overaging in boehmite gels: Colloidal gels respond like soft solids at rest, whereas they flow like\nliquids under external shear. Starting from a fluidized state under an applied\nshear rate $\\dot\\gamma_{p}$, abrupt flow cessation triggers a liquid-to-solid\ntransition during which the stress relaxes towards a so-called \\textit{residual\nstress} $\\sigma_{\\rm res}$ that tallies a macroscopic signature of previous\nshear history. Here, we report on the liquid-to-solid transition in gels of\nboehmite, an aluminum oxide, that shows a remarkable non-monotonic stress\nrelaxation towards a residual stress $\\sigma_{\\rm res}(\\dot\\gamma_{p})$\ncharacterized by a dual behavior relative to a critical value $\\dot\\gamma_{c}$\nof the shear rate $\\dot\\gamma_{p}$. Following shear at\n$\\dot\\gamma_{p}>\\dot\\gamma_{c}$, the gel obtained upon flow cessation is\ninsensitive to shear history, and the residual stress is negligible. However,\nfor $\\dot\\gamma_{p}<\\dot\\gamma_{c}$, the gel encodes some memory of the shear\nhistory, and $\\sigma_{\\rm res}$ increases for decreasing shear rate, directly\ncontributing to reinforcing the gel viscoelastic properties. Moreover, we show\nthat both $\\sigma_{\\rm res}$ and the gel viscoelastic properties increase\nlogarithmically with the strain accumulated during the shear period preceding\nflow cessation. Such a shear-induced \"overaging\" phenomenon bears great\npotential for tuning the rheological properties of colloidal gels.",
        "positive": "Stratified horizontal flow in vertically vibrated granular layers: A layer of granular material on a vertically vibrating sawtooth-shaped base\nexhibits horizontal flow whose speed and direction depend on the parameters\nspecifying the system in a complex manner. Discrete-particle simulations reveal\nthat the induced flow rate varies with height within the granular layer and\noppositely directed flows can occur at different levels. The behavior of the\noverall flow is readily understood once this novel feature is taken into\naccount."
    },
    {
        "anchor": "Extrapolation theory for Stokes flow past a deformed sphere: We formulate a method for computing Stokes flow past a highly deformed sphere\nwith arbitrarily defined surface velocity. The fundamental ingredient is an\nexplicit extrapolation operator extending a velocity field from the surface of\na sphere, which is expressed in terms of a complete set of basis Stokes fields\nfor the pressure and velocity derived from scalar and vector spherical\nharmonics. We present a matrix algebra packaging suitable for numerical\ncomputation to arbitrary order in the deformation amplitude (deviation from\nsphericity). The hydrodynamic force and torque on a deformed sphere with\narbitrary surface velocity are expressed in terms of basis field amplitudes,\nand for the classic problem of a rotating and translating rigid body, we\ncompute explicitly the first order in deformation corrections to the flow field\nas well as the hydrodynamic force and torque.",
        "positive": "Orientational correlation and velocity distributions in uniform shear\n  flow of a dilute granular gas: Using particle simulations of the uniform shear flow of a rough dilute\ngranular gas, we show that the translational and rotational velocities are\nstrongly correlated in direction, but there is no orientational\ncorrelation-induced singularity at perfectly smooth ($\\beta=-1$) and rough\n($\\beta=1$) limits for elastic collisions ($e=1$); both the translational and\nrotational velocity distribution functions remain close to a Gaussian for these\ntwo limiting cases. Away from these two limits, the orientational as well as\nspatial velocity correlations are responsible for the emergence of non-Gaussian\nhigh velocity tails. The tails of both distribution functions follow stretched\nexponentials, with the exponents depending on normal ($e$) and tangential\n($\\beta$) restitution coefficients."
    },
    {
        "anchor": "Liquid crystalline phases and demixing in binary mixtures of\n  shape-anisometric colloids: A theoretical model of shape-anisometric particles embedded in a cubic\nlattice is formulated for binary mixtures combining rod-like, plate-like and\nspherical particles. The model aims at providing a tool for the prediction and\ninterpretation of complex phase behavior in a variety of liquid crystalline\ncolloids, biological and macromolecular systems. Introducing just repulsive\ninteractions among the particles, a rich variety of phase structures and\nmultiphasic equilibria is obtained, including isotropic, nematic, lamellar and\ncolumnar phases, demixing into phases of the same or different symmetries and\nstructural microsegregation of the different species of the mixture within the\nsame phase.",
        "positive": "Quantum theory of photonic crystal polaritons: We formulate a full quantum mechanical theory of the interaction between\nelectromagnetic modes in photonic crystal slabs and quantum well excitons\nembedded in the photonic structure. We apply the formalism to a high index\ndielectric layer with a periodic patterning suspended in air. The strong\ncoupling between electromagnetic modes lying above the cladding light line and\nexciton center of mass eigenfunctions manifests itself with the typical\nanticrossing behavior. The resulting band dispersion corresponds to the\nquasi-particles coming from the mixing of electromagnetic and material\nexcitations, which we call photonic crystal polaritons. We compare the results\nobtained by using the quantum theory to variable angle reflectance spectra\ncoming from a scattering matrix approach, and we find very good quantitative\nagreement."
    },
    {
        "anchor": "Self-organized Beating and Swimming of Internally Driven Filaments: We study a simple two-dimensional model for motion of an elastic filament\nsubject to internally generated stresses and show that wave-like propagating\nshapes which can propel the filament can be induced by a self-organized\nmechanism via a dynamic instability. The resulting patterns of motion do not\ndepend on the microscopic mechanism of the instability but only of the filament\nrigidity and hydrodynamic friction. Our results suggest that simplified\nsystems, consisting only of molecular motors and filaments could be able to\nshow beating motion and self-propulsion.",
        "positive": "Fluid ferroelectric filaments: Freestanding slender fluid filaments of room temperature ferroelectric\nnematic liquid crystals are described. They are stabilized either by internal\nelectric fields of bound charges formed due to polarization splay, or by\nexternal voltage applied between suspending wires. The phenomenon is similar to\nthose observed in dielectric fluids, such as deionized water, except that in\nferroelectric nematic materials the voltages required are 3 orders of\nmagnitudes smaller and the aspect ratio is much higher. The observed\nferroelectric fluid threads are not only unique and novel, but also offer\nmeasurements of basic physical quantities, such as the ferroelectric\npolarization and viscosity. Ferroelectric nematic fluid threads may have\npractical applications in nano-fluidic micron-size logic devices, switches, and\nrelays."
    },
    {
        "anchor": "Interactions of charged microrods in chiral nematic liquid crystals: We study the pair interaction of charged silica microrods in chiral nematic\nliquid crystals and show that the microrods with homeotropic surface anchoring\nform a bound state due to the competing effect of electrostatic (Coulomb) and\nelastic interactions. The robustness of the bound state is demonstrated by\napplying external electrical and mechanical forces that perturbs their\nequilibrium position as well as orientation. In the bound state we have\nmeasured the correlated thermal fluctuations of the position, using\ntwo-particle cross-correlation spectroscopy that uncovers their hydrodynamic\ninteraction. These findings reveal unexplored aspects of liquid-crystal\ndispersions which are important for understanding the assembly and dynamics of\nnano and microparticles in chiral nematic liquid crystals.",
        "positive": "Penetration of fast projectiles into resistant media: from macroscopic\n  to subatomic projectiles: The penetration of a fast projectile into a resistant medium is a complex\nprocess that is suitable for simple modeling, in which basic physical\nprinciples can be profitably employed. This study connects two different\ndomains: the fast motion of macroscopic bodies in resistant media and the\ninteraction of charged subatomic particles with matter at high energies, which\nfurnish the two limit cases of the problem of penetrating projectiles of\ndifferent sizes. These limit cases actually have overlapping applications; for\nexample, in space physics and technology. The intermediate or mesoscopic domain\nfinds application in atom cluster implantation technology. Here it is shown\nthat the penetration of fast nano-projectiles is ruled by a slightly modified\nNewton's inertial quadratic force, namely, $F \\sim v^{2-\\beta}$, where $\\beta$\nvanishes as the inverse of projectile diameter. Factors essential to\npenetration depth are ratio of projectile to medium density and projectile\nshape."
    },
    {
        "anchor": "Active crystals and their stability: A recently introduced active phase field crystal model describes the\nformation of ordered resting and traveling crystals in systems of\nself-propelled particles. Increasing the active drive, a resting crystal can be\nforced to perform collectively ordered migration as a single traveling object.\nWe demonstrate here that these ordered migrating structures are linearly\nstable. In other words, during migration, the single crystalline texture\ntogether with the globally ordered collective motion is preserved even on large\nlength scales. Furthermore, we consider self-propelled particles on a substrate\nthat are surrounded by a thin fluid film. We find that in this case the\nresulting hydrodynamic interactions can destabilize the order.",
        "positive": "Structure Factor of a Lamellar Smectic Phase with Inclusions: Motivated by numerous X-ray scattering studies of lamellar phases with\nmembrane proteins, amphiphilic peptides, polymers, or other inclusions, we have\ndetermined the modifications of the classical Caille law for a smectic phase as\na function of the nature and concentration of inclusions added to it. Besides a\nfundamental interest on the behavior of fluctuating systems with inclusions, a\nprecise characterization of the action of a given protein on a lipid membrane\n(anchoring, swelling, stiffening ...) is of direct biological interest and\ncould be probed by way of X-ray measurements. As a first step we consider three\ndifferent couplings involving local pinching (or swelling), stiffening or tilt\nof the membrane. In the first two cases we predict that independent inclusions\ninduce a simple renormalization of the bending and compression modulii of the\nsmectic phase. The X-ray experiments may also be used to probe correlations\nbetween inclusions. Finally we show that asymmetric coupling (such as a local\ntilt of the membrane) results in a modification of the usual Caille law."
    },
    {
        "anchor": "Fast Membranes Hemifusion via Dewetting between Lipid Bilayers: The behavior of lipid bilayer is important to understand the functionality of\ncells like the trafficking of ions between cells. Standard procedures to\nexplore the properties of lipid bilayer and hemifused states typically use\neither supported membranes or vesicles. Both techniques have several\nshortcoming in terms of bio relevance or accessibility for measurements. In\nthis article the formation of individual free standing hemifused states between\nmodel cell membranes is studied using an optimized microfluidic scheme which\nallows for simultaneous optical and electrophysiological measurements. In a\nfirst step, two model membranes are formed at a desired location within a\nmicrofluidic device using a variation of the droplet interface bilayer (DiB)\ntechnique. In a second step, the two model membranes are brought into contact\nforming a single hemifused state. For all tested lipids, the hemifused state\nbetween free standing membranes form within hundreds of milliseconds, i.e.\nseveral orders of magnitude faster than reported in literature. The formation\nof a hemifused state is observed as a two stage process, whereas the second\nstage can be explained as a dewetting process in no-slip boundary condition.\nThe formed hemifusion states are long living and a single fusion event can be\nobserved when triggered by an applied electric field as demonstrated for\nmonoolein.",
        "positive": "Phase separation in complex mixtures with many components: analytical\n  expressions for spinodal and critical manifolds: The phase behaviour of systems composed of an arbitrary high number of\ncomponents N is investigated. Liquid-liquid phase separation is modelled using\na virial expansion up to second order of the concentrations of the components.\nFormal analytical expressions for the spinodal and critical manifolds in N\ndimensions are derived, simplifying the calculations for the composition of the\nco-existing phases. The present analytical procedure complements previous\nattempts to handle spinodal decomposition for many components, e.g. one using a\nstatistical approach based on Random Matrix Theory. Our results hold promise\nfor addressing liquid-liquid phase separation in the cytosol of living cells,\nwhich is currently a highly active field of research. The results are also\nrelevant for predicting effects of polydispersity on phase behaviour in more\nclassical fields, like polymer and food technology."
    },
    {
        "anchor": "A Boundary-Spheropolygon Element Method for Stress Determination and\n  Breakage Modelling of Particles: We present a boundary-spheropolygon element method (BSEM), that combines the\nboundary integral method (BIM) and the spheropolygon-based discrete element\nmethod (SEM). The interaction between particles is simulated via the SEM, and\nthe sub-particle stress (stress inside the grains) is calculated by BIM. The\nframework of BSEM is presented. Then the accuracy and efficiency of the method\nare analysed by comparison with both analytical solutions and a\nwell-established finite element method (ABAQUS). The results demonstrate that\nBSEM could efficiently provide instant sub-particle stress for irregular\nparticles with an optimized compromise between computational time and accuracy.\nThe effect of particles aspect ratio, coordination number and heterogeneity on\nthe sub-particle stress are discussed through parametric studies. Key\nconclusions on particle breakage are derived based on the analysis of the\ndistribution of the sub-particle tensile stress. The simulation results suggest\nthat BSEM could overcome most of the disadvantages of existing numerical\nmethods and must be used for advanced simulations of particle breakage",
        "positive": "Advection kinetics induced self assembly of colloidal nanoflakes into\n  microscale floral structures: This article explores the governing role of the internal hydrodynamics and\nadvective transport within sessile colloidal droplets on the self assembly of\nnanostructures to form floral patterns. Water acetone binary fluid and Bi2O3\nnanoflakes based complex fluids are experimented with. Microliter sessile\ndroplets are allowed to vaporize and the dry out patterns are examined using\nscanning electron microscopy. The presence of distributed self assembled rose\nlike structures is observed. The population density, structure and shape of the\nfloral structures are noted to be dependent on the binary fluid composition and\nnanomaterial concentration. Detailed microscopic particle image velocimetry\nanalysis is undertaken to qualitatively and quantitatively describe the solutal\nMarangoni advection within the evaporating droplets. It has been shown that the\nkinetics, regime and location of the internal advection are responsible factors\ntowards the hydrodynamics influenced clustering, aggregation and self-assembly\nof the nanoflakes. In addition, the size of the nanostructures and the complex\nfluids."
    },
    {
        "anchor": "Diffusion-controlled intrachain reactions in polymer: An analytical\n  model: A theory of diffusion-controlled intramolecular reactions of polymer chain in\ndilute solution is formulated. Our model is based on the widely used\ndiffusion-reaction formalism of Wilemski and Fixman (J. Chem. Phys. 60, 866\n(1974). Our model is more general than the model proposed by Wilemski and\nFixman, in the sense that our model considers the motion of both close and open\nchain polymer explicitely. It is quite unlikely that the motion of close chain\npolymer do not play any role in the loop formation dynamics, but unfortunately\nthis fact was not considered in any of the earlier studies.",
        "positive": "Rapid-Prototyping a Brownian Particle in an Active Bath: Particles kicked by external forces to produce mobility distinct from thermal\ndiffusion are an iconic feature of the active matter problem. Here, we map this\nonto a minimal model for experiment and theory covering the wide time and\nlength scales of usual active matter systems. A particle diffusing in a\nharmonic potential generated by an optical trap is kicked by programmed forces\nwith time correlation at random intervals following the Poisson process. The\nmodel's generic simplicity allows us to find conditions for which displacements\nare Gaussian (or not), how diffusion is perturbed (or not) by kicks, and\nquantifying heat dissipation to maintain the non-equilibrium steady state in an\nactive bath. The model reproduces experimental results of tracer mobility in an\nactive bath of swimming algal cells. It can be used as a stochastic dynamic\nsimulator for Brownian objects in various active baths without mechanistic\nunderstanding, owing to the generic framework of the protocol."
    },
    {
        "anchor": "Aggregation Patterns of Salt Crystalizing in Drying Colloidal Solvents: We report a study of the structure of droplets of colloidal gels containing\ndissolved sodium chloride. The components segregate and form intricate\npatterns. The salt crystalizes in fractal and multi-fractal dendritic forms\nwhich are determined by the material which forms the colloidal gel. Here potato\nstarch, gelatine and carboxymethyl cellulose have been used. The substrate also\nplays a role in some cases. Photographs and micrographs at different level of\nmagnification are shown.",
        "positive": "Dynamic Kerr effect responses in the Terahertz-range: Dynamic Kerr effect measurements provide a simple realization of a nonlinear\nexperiment. We propose a field-off experiment where an electric field of one or\nseveral sinusoidal cycles is applied to a sample in thermal equilibrium.\nAfterwards, the evolution of the polarizability is measured. If such an\nexperiment is performed in the Terahertz-range it might provide valuable\ninformation about the low-frequency dynamics in disordered systems. We treat\nthese dynamics in terms of a Brownian oscillator model and calculate the Kerr\neffect response. It is shown that frequency-selective behaviour can be\nexpected. In the interesting case of underdamped vibrational motion we find\nthat the frequency-dependence of the phonon-damping can be determined from the\nexperiment. Also the behaviour of overdamped relaxational modes is discussed.\nFor typical glassy materials we estimate the magnitude of all relevant\nquantities, which we believe to be helpful in experimental realizations."
    },
    {
        "anchor": "Truncated correlations in video microscopy of colloidal solids: Studies by video microscopy on fluctuating colloids measure the real-space\ncross-correlations in particle motion. This set of correlations is then treated\nas a matrix, in order to study the spectrum and mode structure. We show that in\ngeneral the modes are modified by the truncation of the full real-space\ncorrelations. We perform a theoretical analysis of the truncation, find the\nboundary conditions imposed by the truncation, and propose practical windowing\nstrategies to eliminate artefacts. We study the problem from various\nperspectives, to compile a survey for experimentalists.",
        "positive": "Structure of cylindrical electric double layers: Comparison of density\n  functional and modified Poisson-Boltzmann theories with Monte Carlo\n  simulations: The structure of cylindrical double layers is studied using a modified\nPoisson Boltzmann theory and the density functional approach. In the model\ndouble layer, the electrode is a cylindrical polyion that is infinitely long,\nimpenetrable, and uniformly charged. The polyion is immersed in a sea of\nequi-sized rigid ions embedded in a dielectric continuum. An in-depth\ncomparison of the theoretically predicted zeta potentials, the mean\nelectrostatic potentials, and the electrode-ion singlet density distributions\nis made with the corresponding Monte Carlo simulation data. The theories are\nseen to be consistent in their predictions that include variations in ionic\ndiameters, electrolyte concentrations, and electrode surface charge densities,\nand are also capable of well reproducing some new and existing Monte Carlo\nresults."
    },
    {
        "anchor": "Intramolecular distances and form factor of cyclic chains with excluded\n  volume interactions: Numerical simulations are performed for isolated cyclic chains with excluded\nvolume. Data are reported for the form factor, S(x), where x is the reduced\nscattering variable, and also for averages and distributions of the distance\nbetween intramolecular units. The averages of distances are compared with two\nalternative expressions describing their dependence with the number of segments\nseparating the units. The distribution function results are compared with the\ndes Cloizeaux form. Finally the S(x) data are compared with theoretical\nfunctions also derived from the des Cloizeaux expression for the distribution\nfunction. Moreover, the low x and asymptotic expansions of these functions are\nobtained. Based on these expansions, simple formulas are proposed to give a\ngood description of the simulation data in the whole range of values of x. A\ncomparison with similar results for linear chains is also included.",
        "positive": "Dewetting dynamics of stressed viscoelastic thin polymer films: Ultrathin polymer films that are produced e.g. by spin-coating are believed\nto be stressed since polymers are 'frozen in' into out-of-equilibrium\nconfigurations during this process. In the framework of a viscoelastic thin\nfilm model, we study the effects of lateral residual stresses on the dewetting\ndynamics of the film. The temporal evolution of the height profiles and the\nvelocity profiles inside the film as well as the dissipation mechanisms are\ninvestigated in detail. Both the shape of the profiles and the importance of\nfrictional dissipation vs. viscous dissipation inside the film are found to\nchange in the course of dewetting. The interplay of the non-stationary\nprofiles, the relaxing initial stress and changes in the dominance of the two\ndissipation mechanisms caused by nonlinear friction with the substrate is\nresponsible for the rich behavior of the system. In particular, our analysis\nsheds new light on the occurrence of the unexpected maximum in the rim width\nobtained recently in experiments on PS-PDMS systems."
    },
    {
        "anchor": "Orthogonality catastrophe and decoherence of a confined Bose-Einstein\n  condensate at finite temperature: We discuss mechanisms of decoherence of a confined Bose-Einstein condensate\nat finite temperatures under the explicit condition of conservation of the\ntotal number of bosons $N$ in the trap. A criterion for the irreversible decay\nof the condensate two-time correlator is formulated in terms of the {\\it\nOrthogonality Catastrophe} (OC) for the exact N-body eigenstates, so that no\nirreversible decay occurs without the OC. If an infinite external bath contacts\na finite condensate, the OC should practically always occur as long as the bath\ndegrees o freedom are interacting with each other. We claim that, if no\nexternal bath is present and the role of the bath is played by the normal\ncomponent, no irreversible decay occurs. We discuss the role of the effect of\nthe {\\it level repulsion} in eliminating the OC. At finite temperatures, the\ntime-correlations of the condensate isolated from the environment are dominated\nby the reversible dephasing which results from the thermal ensemble averaging\nover realizations of the normal component. Accordingly, the correlator exhibits\nthe gaussian decay with certain decay time $\\tau_d$ dependent on temperature as\nwell as on intensity of the shot noise determined by the statistical\nuncertainty in the number of bosons $N$ deposited into the trap. We estimate\n$\\tau_d$ for the conditions resembling those realized in the JILA experiment,\nand obtain the value close to 1s, if no shot noise is taken into account. At\ntemperatures as large as 0.5 of the temperature of the Bose-Einstein\ncondensation, $\\tau_d \\leq 100$ms. Depending on the variance $\\Delta N$ of $N$,\ninclusion of the shot noise may shorten these times.",
        "positive": "Exploration of vitrification of water and Kauzmann entropy through\n  complex specific heat: A journey through 'No Man's Land': Frequency dependent specific heat, introduced by Grest and Nagel, offers\nvaluable insight into the vitrification of supercooled liquid. We calculate\nthis quantity and other thermodynamic properties of supercooled liquid water by\nvarying temperature and density across the \"no man's land\" all the way to the\nformation of amorphous ice. The calculations are aided by very long computer\nsimulations, often more than 50 $\\mu s$ long. Density fluctuations that arise\nfrom the proximity to a putative liquid-liquid (LL) transition at 228 K, cast a\nlong shadow on the properties of water, both above and below the LL transition.\nWe carry out the calculation of the quantum mechanical static and\nfrequency-dependent specific heats by combining seminal works by Lebowitz,\nPercus, and Verlet and Grest and Nagel with the harmonic approximation for the\ndensity of states. The obtained values are in quantitative agreement with all\navailable experimental and numerical results of specific heats for both\nsupercooled water and ice. We calculate the entropy at all the state points by\nintegrating the specific heat. We find that the quantum corrected-contributions\nof intermolecular vibrational entropy dominate the excess entropy of amorphous\nphases over the crystal over a wide range of temperature. Interestingly, the\nvibrational entropy lowers the Kauzmann temperature, $T_{\\rm K}$, to 130 K,\njust below the experimental glass-to-liquid water transition temperature,\n$T_{\\rm g}$, of 136 K and the calculated $T_{\\rm g}$ of 135 K in our previous\nstudy. A straightforward extrapolation of high temperature entropy from 250 K\nto below however would give a much higher value of $T_{\\rm K}$ $\\sim$ 190 K.\nThe calculation of Lindemann ratios places the melting of amorphous ice $\\sim$\n135 K. The amorphous state exhibits an extremely short correlation length for\nthe distance dependence of orientational correlation."
    },
    {
        "anchor": "The Inherent Structure Landscape Connection Between Liquids, Granular\n  materials and the Jamming Phase Diagram: We provide a comprehensive picture of the jamming phase diagram by connecting\nthe athermal, granular ensemble of jammed states and the equilibrium fluid\nthrough the inherent structure paradigm for a system hard discs confined to a\nnarrow channel. The J-line is shown to be divided into packings that are\nthermodynamically accessible from the equilibrium fluid and inaccessible\npackings. The J-point is found to occur at the transition between these two\nsets of packings and is located at the maximum the inherent structure\ndistribution. A general thermodynamic argument suggests that the density of the\nstates at the configurational entropy maximum represents a lower bound on the\nJ-point density in hard sphere systems. Finally, we find that the granular and\nfluid systems only occupy the same set of inherent structures, under the same\nthermodynamic conditions, at two points, corresponding to zero and infinite\npressures, where they sample the J-point states and the most dense packing\nrespectively.",
        "positive": "Propagation Dynamics of a Particle Phase in a Single-File Pore: We study propagation dynamics of a particle phase in a single-file pore\nconnected to a reservoir of particles (bulk liquid phase). We show that the\ntotal mass $M(t)$ of particles entering the pore up to time $t$ grows as $M(t)\n= 2 m(J,\\rho_F) \\sqrt{D_0 t}$, where $D_0$ is the \"bare\" diffusion coefficient\nand the prefactor $m(J,\\rho_F)$ is a non-trivial function of the reservoir\ndensity $\\rho_F$ and the amplitude $J$ of attractive particle-particle\ninteractions. Behavior of the dynamic density profiles is also discussed."
    },
    {
        "anchor": "dPOLY: Deep Learning of Polymer Phases and Phase Transition: Machine learning (ML) and artificial intelligence (AI) have the remarkable\nability to classify, recognize, and characterize complex patterns and trends in\nlarge data sets. Here, we adopt a subclass of machine learning methods viz.,\ndeep learnings and develop a general-purpose AI tool - dPOLY for analyzing\nmolecular dynamics trajectory and predicting phases and phase transitions in\npolymers. An unsupervised deep neural network is used within this framework to\nmap a molecular dynamics trajectory undergoing thermophysical treatment such as\ncooling, heating, drying, or compression to a lower dimension. A supervised\ndeep neural network is subsequently developed based on the lower dimensional\ndata to characterize the phases and phase transition. As a proof of concept, we\nemploy this framework to study coil to globule transition of a model polymer\nsystem. We conduct coarse-grained molecular dynamics simulations to collect\nmolecular dynamics trajectories of a single polymer chain over a wide range of\ntemperatures and use dPOLY framework to predict polymer phases. The dPOLY\nframework accurately predicts the critical temperatures for the coil to globule\ntransition for a wide range of polymer sizes. This method is generic and can be\nextended to capture various other phase transitions and dynamical crossovers in\npolymers and other soft materials.",
        "positive": "Depolarized light scattering and dielectric response of a peptide\n  dissolved in water: The density and orientational relaxation of bulk water can be separately\nstudied by depolarized light scattering (DLS) and dielectric spectroscopy (DS),\nrespectively. Here we ask the question of what are the leading collective modes\nresponsible for polarization anisotropy relaxation (DLS) and dipole moment\nrelaxation (DS) of solutions involving mostly hydrophobic solute-water\ninterfaces. We study, by atomistic molecular dynamics simulations, the dynamics\nand structure of hydration water interfacing N-Acetyl-leucine-methylamide\n(NALMA) dipeptide. The DLS response of the solution is consistent with three\nrelaxation processes: bulk water, rotations of single solutes, and collective\ndipole-induced-dipole polarizability of the solutes, with the time-scale of\n130-200 ps. No separate DLS response of the hydration shell has been identified\nby our simulations. Density fluctuations of the hydration layer, which largely\ncontribute to the response, do not produce a dynamical process distinct from\nbulk water. We find that the structural perturbation of the orientational\ndistribution of hydration waters by the dipeptide solute is quite significant\nand propagates 3-5 hydration layers into the bulk. This perturbation is still\nbelow that produced by hydrated globular proteins. Despite this structural\nperturbation, there is little change in the orientational dynamics of the\nhydration layers, compared to the bulk, as probed by both single-particle\norientational dynamics and collective dynamics of the dipole moment of the\nshells. There is a clear distinction between the perturbation of the\ninterfacial structure by the solute-solvent interaction potential and the\nperturbation of the interfacial dynamics by the corresponding forces."
    },
    {
        "anchor": "Finite-size and asymptotic behaviors of the gyration radius of knotted\n  cylindrical polygons: Several nontrivial properties are shown for the mean square radius of\ngyration $R_K^2$ of ring polymers with a fixed knot type K.\n  Through computer simulation, we discuss both finite-size and asymptotic\nbehaviors of the gyration radius under the topological constraint for\nself-avoiding polygons consisting of N cylindrical segments with radius r. We\nfind that the average size of ring polymers with a knot K can be much larger\nthan that of no topological constraint. The effective expansion due to the\ntopological constraint depends strongly on the parameter r which is related to\nthe excluded volume. The topological expansion is particularly significant for\nthe small r case, where the simulation result is associated with that of random\npolygons with the knot K.",
        "positive": "The Panic Model: Flocking with Minimal Cooperativity: We present a 2D lattice model of self-propelled spins that can only change\ndirection upon collision with another spin. We show that even with ballistic\nmotion and minimal cooperativity, these spins display robust flocking behavior\nat nearly all densities, forming long bands of stripes. The structural\ntransition in this system can be characterized by an order parameter, and we\ndemonstrate that if this parameter is studied as a dynamical variable rather\nthan a steady-state observable, we can extract a detailed picture of how the\nflocking mechanism varies with density."
    },
    {
        "anchor": "Growth of Bose-Einstein Condensates from Thermal Vapor: We report on a quantitative study of the growth process of $^{87}$Rb\nBose-Einstein condensates. By continuous evaporative cooling we directly\ncontrol the thermal cloud from which the condensate grows. We compare the\nexperimental data with the results of a theoretical model based on quantum\nkinetic theory. We find quantitative agreement with theory for the situation of\nstrong cooling, whereas in the weak cooling regime a distinctly different\nbehaviour is found in the experiment.",
        "positive": "Automated assignment of SCOP and CATH protein structure classification\n  from FSSP scores: We present an automated procedure to assign CATH and SCOP classifications to\nproteins whose FSSP score is available. CATH classification is assigned down to\nthe topology level and SCOP classification to the fold level. As the FSSP\ndatabase is updated weekly, this method makes it possible to update also CATH\nand SCOP with the same frequency. Our predictions have a nearly perfect success\nrate when ambiguous cases are discarded. These ambiguous cases are intrinsic in\nany protein structure classification, which relies on structural information\nalone. Hence, we introduce the notion of ``twilight zone for structure\nclassification''. We further suggest that in order to resolve these ambiguous\ncases other criteria of classification, based also on information about\nsequence and function, must be used."
    },
    {
        "anchor": "First passage of a particle in a potential under stochastic resetting: a\n  vanishing transition of optimal resetting rate: First passage in a stochastic process may be influenced by the presence of an\nexternal confining potential, as well as \"stochastic resetting\" in which the\nprocess is repeatedly reset back to its initial position. Here we study the\ninterplay between these two strategies, for a diffusing particle in an\none-dimensional trapping potential $V(x)$, being randomly reset at a constant\nrate $r$. Stochastic resetting has been of great interest as it is known to\nprovide an \"optimal rate\" ($r_*$) at which the mean first passage time is a\nminimum. On the other hand an attractive potential also assists in first\ncapture process. Interestingly, we find that for a sufficiently strong external\npotential, the advantageous optimal resetting rate vanishes (i.e. $r_*\\to 0$).\nWe derive a condition for this $optimal$ $resetting$ $rate$ $vanishing$\n$transition$, which is continuous. We study this problem for various functional\nforms of $V(x)$, some analytically, and the rest numerically. We find that the\noptimal rate $r_*$ vanishes with the deviation from critical strength of the\npotential as a power law with an exponent $\\beta$ which appears to be\nuniversal.",
        "positive": "Simulations of Polyelectrolyte Adsorption to a Dielectric Like-Charged\n  Surface: We explore, using the recently developed efficient Monte Carlo simulation\nmethod, the interaction of an anionic polyelectrolyte solution with a\nlike-charged dielectric surface. In addition to polyions, the solution also\ncontains salt with either monovalent, divalent, or trivalent counterions. In\nagreement with recent experimental observations, we find that multivalent\ncounterions can lead to strong adsorption of polyions onto the surface. On the\nother hand, addition of a 1:1 electrolyte diminishes the adsorption induced by\nthe multivalent counterions. Dielectric discontinuity at the interface is found\nto play only a marginal role in polyion adsorption."
    },
    {
        "anchor": "Stokes experiment in a liquid foam: The paper reports on the quasi-static steady flow of a dry liquid foam around\na fixed spherical bead, few times larger than the typical bubble size. The\nforce exerted on the bead is recorded with a precision and a time resolution\nlarge enough to show the succession of elastic loading of the foam, separated\nby sudden force drops. The foam structure is observed by direct light\ntransmission, synchronized with the force measurement, thus allowing to\ncorrelate the plastic events with the force variations. Scaling laws for the\nforce signal as a function of the bubble size are detailed and interpreted with\na simple elasto-plastic model. The spatial distribution of the plasticity is\nstrongly localized in the first bubbles layers around the bead and the average\nsize of bubble rearrangements increases with the corresponding force jump\namplitude.",
        "positive": "Dynamics of Domain Growth in Self-Assembled Fluid Vesicles: The dynamics of phase separation in multi-component bilayer fluid vesicles is\ninvestigated by means of large-scale dissipative particle dynamics. The model\nexplicitly accounts for solvent particles, thereby allowing for the very first\nnumerical investigation of the effects of hydrodynamics and area-to-volume\nconstraints. We observed regimes corresponding to coalescence of flat patches,\nbudding and vesiculation, and coalescence of caps. We point out that the\narea-to-volume constraint has a strong influence on crossovers between these\nregimes."
    },
    {
        "anchor": "Competition of Mesoscales and Crossover to Tricriticality in Polymer\n  Solutions: We show that the approach to asymptotic fluctuation-induced critical behavior\nin polymer solutions is governed by a competition between a correlation length\ndiverging at the critical point and an additional mesoscopic length-scale, the\nradius of gyration. Accurate light-scattering experiments on polystyrene\nsolutions in cyclohexane with polymer molecular weights ranging from 200,000 up\nto 11.4 million clearly demonstrate a crossover between two universal regimes:\na regime with Ising asymptotic critical behavior, where the correlation length\nprevails, and a regime with tricritical theta-point behavior determined by a\nmesoscopic polymer-chain length.",
        "positive": "Beading instability and spreading kinetics in grooves with convex curved\n  sides: The coarsening kinetics for the beading instability for liquid contained in a\ngroove with convex curved sides (for example between a pair of parallel\ntouching cylinders) is considered as an open channel flow problem. In contrast\nto a V-shaped wedge or U-shaped microchannel, it is argued that droplet\ncoarsening takes place by viscous hydrodynamic transport through a stable\ncolumn of liquid that coexists with the droplets in the groove at a slightly\npositive Laplace pressure. With some simplifying assumptions, this leads to a\nt^(1/7) growth law for the characteristic droplet size as a function of time,\nand a t^(-3/7) law for the decrease in the droplet line density. Some remarks\nare also made on the spreading kinetics of an isolated drop deposited in such a\ngroove."
    },
    {
        "anchor": "Water in an electric field does not dance alone: The relation between\n  equilibrium structure, time dependent viscosity and molecular motions: Dynamic structuring of water is a key player in a large class of processes\nunderlying biochemical and technological developments today, the latter often\ninvolving electric fields. However, the anisotropic coupling between the water\nstructure and the field has not been understood on a molecular level so far.\nHere we perform extensive molecular dynamics simulations to explore the\ninfluence of an externally imposed electric field on liquid water under ambient\nconditions. Using self-developed analysis tools and rigorous statistical\nanalysis, we unambiguously show that water hydration shells break into\nsubcompartments, which were hitherto not observed due to radial averaging. The\nshape of subcompartments is sensitive to the field magnitude, and affects\nexcitations of the hydrogen bond network including the femtosecond stretching\nand the sub-picosecond restructuring of hydrogen bonds. Furthermore, by\nanalysing the reorientational dynamics of water molecules, we ascertain the\nexistence of cooperative excitations of small water clusters. Enabled by the\ninterplay between hydrogen bonding, and the coupling of water dipoles to the\nfield, these coordinated motions, occurring on the picosecond time scale, are\nassociated with fluctuations between torque-free states of water dipoles. We\nshow that unlike the coupling between translation and reorientation of water\nmolecules, which takes place on even longer time scales, these coordinated\nmotions are the key for understanding the emergent anisotropy of diffusion and\nviscosity of water. Particular effort is invested to provide an analysis that\nallows for future experimental validation.",
        "positive": "Glassy behavior in systems with Kac-type step-function interaction: We study a system with a weak, long-range repulsive Kac-type step-function\ninteraction within the framework of a replicated effective $\\phi^4$-theory. The\noccurrence of extensive configurational entropy, or an exponentially large\nnumber of metastable minima in the free energy (characteristic of a glassy\nstate), is demonstrated. The underlying mechanism of mesoscopic patterning and\ndefect organizations is discussed."
    },
    {
        "anchor": "Novel Fluctuations at a Constrained Liquid-Solid Interface: We study the interface between a solid trapped within a bath of liquid by a\nsuitably shaped non-uniform external potential. Such a potential may be\nconstructed using lasers, external electric or magnetic fields or a surface\ntemplate. We study a two dimensional case where a thin strip of solid, created\nin this way, is surrounded on either side by a bath of liquid with which it can\neasily exchange particles. Since height fluctuations of the interface cost\nenergy, this interface is constrained to remain flat at all length scales.\nHowever, when such a solid is stressed by altering the depth of the potential;\nbeyond a certain limit, it responds by relieving stress by novel interfacial\nfluctuations which involve addition or deletion of entire lattice layers of the\ncrystal. This ``layering'' transition is a generic feature of the system\nregardless of the details of the interaction potential. We show how such\ninterfacial fluctuations influence mass, momentum and energy transport across\nthe interface. Tiny momentum impulses produce weak shock waves which travel\nthrough the interface and cause the spallation of crystal layers into the\nliquid. Kinetic and energetic constraints prevent spallation of partial layers\nfrom the crystal, a fact which may be of some practical use. We also study heat\ntransport through the liquid-solid interface and obtain the resistances in\nliquid, solid and interfacial regions (Kapitza resistance) as the solid\nundergoes such layering transitions. Heat conduction, which shows strong\nsignatures of the structural transformations, can be understood using a free\nvolume calculation.",
        "positive": "A simple equation to calculate the diameters of biological vesicles: The remarkable preference of biomembranes, to constitute vesicles of certain\ndiscrete sizes is explained by using the following properties of phospholipids\nthat are either well understood or at least documented.\n  A. By hexagonal close-packing their fatty acyl chains form a triangular\nlattice.\n  Their molecules:\n  B. Prefer to form linear arrays that occasionally make angles of 120 degrees.\n  C. Form relatively large hexagons. Based on these properties a model for\nmonolayers is proposed and a simple equation derived for the calculation of\ndiameters of vesicles. The diameters of vesicles of neurotransmitters and\nhormones determined by electron microscopy were compared with those obtained\nwith the equation. Statistical analysis of this comparison revealed the model\nto give very significant results (p=.0002)."
    },
    {
        "anchor": "Observation of condensed phases of quasi-planar core-softened colloids: We experimentally study the condensed phases of repelling core-softened\nspheres in two dimensions. The dipolar pair repulsion between superparamagnetic\nspheres trapped in a thin cell is induced by a transverse magnetic field and\nsoftened by suitably adjusting the cell thickness. We scan a broad density\nrange and we materialize a large part of the theoretically predicted phases in\nsystems of core-softened particles, including expanded and close-packed\nhexagonal, square, chain-like, stripe/labyrinthine, and honeycomb phase.\nFurther insight into their structure is provided by Monte Carlo simulations.",
        "positive": "Self-Consistent-Field Study of Adsorption and Desorption Kinetics of\n  Polyethylene Melts on Graphite and Comparison with Atomistic Simulations: A method is formulated, based on combining self-consistent field theory with\ndynamically corrected transition state theory, for estimating the rates of\nadsorption and desorption of end-constrained chains (e.g. by crosslinks or\nentanglements) from a polymer melt onto a solid substrate. This approach is\ntested on a polyethylene/graphite system, where the whole methodology is\nparametrized by atomistically detailed molecular simulations. For short-chain\nmelts, which can still be addressed by molecular dynamics simulations with\nreasonable computational resources, the self-consistent field approach gives\npredictions of the adsorption and desorption rate constants which are\ngratifyingly close to molecular dynamics estimates."
    },
    {
        "anchor": "Glassy dynamics of athermal self-propelled particles: Computer\n  simulations and a nonequilibrium microscopic theory: We combine computer simulations and analytical theory to investigate the\nglassy dynamics in dense assemblies of athermal particles evolving under the\nsole influence of self-propulsion. The simulations reveal that when the\npersistence time of the self-propelled particles is increased, the local\nstructure becomes more pronounced whereas the long-time dynamics first\naccelerates and then slows down. These seemingly contradictory evolutions are\nexplained by constructing a nonequilibrium mode-coupling-like theory for\ninteracting self-propelled particles. To predict the collective dynamics the\ntheory needs the steady state structure factor and the steady state\ncorrelations of the local velocities. It yields nontrivial predictions for the\nglassy dynamics of self-propelled particles in qualitative agreement with the\nsimulations.",
        "positive": "Wetting and Diffusion of Water on Pristine and Strained Phosphorene: Phosphorene, a newly fabricated two-dimensional (2D) nanomaterial, have\nexhibited promising application prospect in biology. Nonetheless, the wetting\nand diffusive properties of bio-fluids on phosphorene are still elusive. In\nthis study, using molecular dynamics (MD) simulations, we investigated the\nstructural and dynamic properties of water on pristine and strained\nphosphorene. The MD simulations illustrated that the diffusion of water\nmolecules on the phosphorene surface is anisotropic, while strain-enhanced\ndiffusion is clearly present which arises from strain-induced smooth of the\nenergy landscape. The contact angle of water droplet on phosphorene exhibited a\nnonmonotonic variation with the transverse strain. The structure of water on\ntransverse stretched phosphorene was demonstrated to be different from that on\nlongitudinal stretched phosphorene. Moreover, we discovered that the contact\nangle of water on strained phosphorene is proportional to the quotient of\nlongitudinal and transverse diffusion coefficients of interfacial water. These\nfindings would offer helpful insights in potential ways of manipulating the\nwetting and transport of water at nanoscale, and in future bio-applications of\nphosphorene."
    },
    {
        "anchor": "Damage in porous media due to salt crystallization: We investigate the origins of salt damage in sandstones for the two most\ncommon salts: sodium chloride and sulfate. The results show that the observed\ndifference in damage between the two salts is directly related to the kinetics\nof crystallization and the interfacial properties of the salt solutions and\ncrystals with respect to the stone. We show that, for sodium sulfate, the\nexistence of hydrated and anhydrous crystals and specifically their dissolution\nand crystallization kinetics are responsible for the damage. Using magnetic\nresonance imaging and optical microscopy we show that when water imbibes sodium\nsulfate contaminated sandstones, followed by drying at room temperature, large\ndamage occurs in regions where pores are fully filled with salts. After partial\ndissolution, anhydrous sodium sulfate salt present in these regions gives rise\nto a very rapid growth of the hydrated phase of sulfate in the form of clusters\nthat form on or close to the remaining anhydrous microcrystals. The rapid\ngrowth of these clusters generates stresses in excess of the tensile strength\nof the stone leading to the damage. Sodium chloride only forms anhydrous\ncrystals that consequently do not cause damage in the experiments.",
        "positive": "Surface acoustic waves in rotating orthorhombic crystals: The propagation of surface (Rayleigh) waves over a rotating orthorhombic\ncrystal is studied. The crystal possesses three crystallographic axes, normal\nto the symmetry planes: the half-space is cut along a plane normal to one of\nthese axes, the wave travels in the direction of another, and the rotation\noccurs at a uniform rate about any of the three axes. The secular equation for\nthe surface wave speed is found explicitly; in contrast to the non-rotating\ncase, it is dispersive (frequency-dependent). Both Coriolis and centrifugal\naccelerations appear in the equations of motion: none can be neglected in favor\nof the other, even at small rotation rates."
    },
    {
        "anchor": "Kinetics of coarsening have dramatic effects on the microstructure:\n  self-similarity breakdown induced by viscosity contrast: The viscous coarsening of a phase separated mixture is studied and the\neffects of the viscosity contrast between the phases are investigated. From an\nanalysis of the microstructure, it appears that for moderate departure from the\nperfectly symmetric regime the self-similar bicontinuous regime is robust.\nHowever, the connectivity of one phase decreases when its volume fraction\ndecreases or when it is becoming less viscous than the complementary phase.\nEventually self-similarity breakdown is observed and characterized.",
        "positive": "Nanoscale Structure and Elasticity of Pillared DNA Nanotubes: We present an atomistic model of pillared DNA nanotubes (DNTs) and their\nelastic properties which will facilitate further studies of these nanotubes in\nseveral important nanotechnological and biological applications. In particular,\nwe introduce a computational design to create an atomistic model of a 6-helix\nDNT (6HB) along with its two variants, 6HB flanked symmetrically by two double\nhelical DNA pillars (6HB+2) and 6HB flanked symmetrically by three double\nhelical DNA pillars (6HB+3). Analysis of 200 ns all-atom simulation\ntrajectories in the presence of explicit water and ions shows that these\nstructures are stable and well behaved in all three geometries. Hydrogen\nbonding is well maintained for all variants of 6HB DNTs. We calculate the\npersistence length of these nanotubes from their equilibrium bend angle\ndistributions. The values of persistence length are ~10 {\\mu}m, which is 2\norders of magnitude larger than that of dsDNA. We also find a gradual increase\nof persistence length with an increasing number of pillars, in quantitative\nagreement with previous experimental findings. To have a quantitative\nunderstanding of the stretch modulus of these tubes we carried out\nnonequilibrium Steered Molecular Dynamics (SMD). The linear part of the force\nextension plot gives stretch modulus in the range of 6500 pN for 6HB without\npillars which increases to 11,000 pN for tubes with three pillars. The values\nof the stretch modulus calculated from contour length distributions obtained\nfrom equilibrium MD simulations are similar to those obtained from\nnonequilibrium SMD simulations. The addition of pillars makes these DNTs very\nrigid."
    },
    {
        "anchor": "Origin of Rigidity in Dry Granular Solids: Solids are distinguished from fluids by their ability to resist shear. In\ntraditional solids, the resistance to shear is associated with the emergence of\nbroken translational symmetry as exhibited by a non-uniform density pattern. In\nthis work, we focus on the emergence of shear-rigidity in a class of solids\nwhere this paradigm is challenged. Dry granular materials have no energetically\nor entropically preferred density modulations. We show that, in contrast to\ntraditional solids, the emergence of shear rigidity in these granular solids is\na collective process, which is controlled solely by boundary forces, the\nconstraints of force and torque balance, and the positivity of the contact\nforces. We develop a theoretical framework based on these constraints, which\nconnects rigidity to broken translational symmetry in the space of forces, not\npositions of grains. We apply our theory to experimentally generated\nshear-jammed (SJ) states and show that these states are indeed characterized by\na persistent, non-uniform density modulation in force space, which emerges at\nthe shear-jamming transition.",
        "positive": "Gaussian and non-Gaussian speckle fluctuations in the diffusing-wave\n  spectroscopy signal of a coarsening foam: All prior applications of Diffusing-Wave Spectroscopy (DWS) to aqueous foams\nrely upon the assumption that the electric field of the detected light is a\nGaussian random variable and that, hence, the Siegert relation applies. Here we\ntest this crucial assumption by simultaneous measurement of both second and\nthird-order temporal intensity correlations. We find that the electric field is\nGaussian for typical experimental geometries equivalent to illumination and\ndetection with a plane wave, both for backscattering and transmission through\nan optically-thick slab. However, we find that the Gaussian character breaks\ndown for point-in / point-out backscattering geometries in which the\nillumination spot size is not sufficiently large in comparison with the size of\nthe intermittent rearrangement events."
    },
    {
        "anchor": "Exact theory of kinkable elastic polymers: The importance of nonlinearities in material constitutive relations has long\nbeen appreciated in the continuum mechanics of macroscopic rods. Although the\nmoment (torque) response to bending is almost universally linear for small\ndeflection angles, many rod systems exhibit a high-curvature softening. The\nsignature behavior of these rod systems is a kinking transition in which the\nbending is localized. Recent DNA cyclization experiments by Cloutier and Widom\nhave offered evidence that the linear-elastic bending theory fails to describe\nthe high-curvature mechanics of DNA. Motivated by this recent experimental\nwork, we develop a simple and exact theory of the statistical mechanics of\nlinear-elastic polymer chains that can undergo a kinking transition. We\ncharacterize the kinking behavior with a single parameter and show that the\nresulting theory reproduces both the low-curvature linear-elastic behavior\nwhich is already well described by the Wormlike Chain model, as well as the\nhigh-curvature softening observed in recent cyclization experiments.",
        "positive": "Computer simulation of topological defects around a colloidal particle\n  or droplet dispersed in a nematic host: We use molecular dynamics to study the ordering of a nematic liquid crystal\naround a spherical particle or droplet. Homeotropic boundary conditions and\nstrong anchoring create a hedgehog director configuration on the particle\nsurface and in its vicinity; this topological defect is cancelled by nearby\ndefect structures in the surrounding liquid crystal, so as to give a uniform\ndirector field at large distances. We observe three defect structures for\ndifferent particle sizes: a quadrupolar one with a ring defect surrounding the\nparticle in the equatorial plane; a dipolar one with a satellite defect at the\nnorth or south pole; and a transitional, non-equatorial, ring defect. These\nobservations are broadly consistent with the predictions of the simplest\nelastic theory. By studying density and order-parameter maps, we are able to\nexamine behaviour near the particle surface, and in the disclination core\nregion, where the elastic theory is inapplicable. Despite the relatively small\nscale of the inhomogeneities in our systems, the simple theory gives reasonably\naccurate predictions of the variation of defect position with particle size."
    },
    {
        "anchor": "The Many Faces of Far-from-equilibrium Thermodynamics: Deterministic\n  Chaos, Randomness or Emergent Order?: Far-from-equilibrium systems are ubiquitous in nature. They are also rich in\nterms of diversity and complexity. Therefore, it is an intellectual challenge\nto be able to understand the physics of far-from-equilibrium phenomena. In this\npaper we revisit a standard tabletop experiment, the Rayleigh-B{\\'e}nard\nconvection, to explore some fundamental questions and present a new perspective\nfrom a first-principles point of view. How non-equilibrium fluctuations differ\nfrom equilibrium fluctuations, how emergence of order out-of-equilibrium breaks\nsymmetries in the system, or how free-energy of a system gets locally\nbifurcated to operate a Carnot-like engine to maintain order? The exploration\nand investigation of these non-trivial questions are the focus of this paper.",
        "positive": "Coarse-grained modelling of the structural properties of DNA origami: We use the oxDNA coarse-grained model to provide a detailed characterization\nof the fundamental structural properties of DNA origamis, focussing on\narchetypal 2D and 3D origamis. The model reproduces well the characteristic\npattern of helix bending in a 2D origami, showing that it stems from the\nintrinsic tendency of anti-parallel four-way junctions to splay apart, a\ntendency that is enhanced both by less screened electrostatic interactions and\nby increased thermal motion. We also compare to the structure of a 3D origami\nwhose structure has been determined by cryo-electron microscopy. The oxDNA\naverage structure has a root-mean-square deviation from the experimental\nstructure of 8.4 Angstrom, which is of the order of the experimental\nresolution. These results illustrate that the oxDNA model is capable of\nproviding detailed and accurate insights into the structure of DNA origamis,\nand has the potential to be used to routinely pre-screen putative origami\ndesigns."
    },
    {
        "anchor": "Tuning intermolecular interactions in di-octyl substituted polyfluorene\n  via hydrostatic pressure: Polyfluorenes (PFs) represent a unique class of poly para-phenylene based\nblue-emitting polymers with intriguing structure-property relationships. Slight\nvariations in the choice of functionalizing side chains result in dramatic\ndifferences in the inter- and intra-chain structures in PFs. We present\nphotoluminescence (PL) and Raman scattering studies of bulk samples and thin\nfilms of dioctyl-substituted PF (PF8) under hydrostatic pressure. The bulk\nsample was further thermally annealed at 1.9 GPa. The PL vibronics of the as-is\nsample red-shift at an average rate of 26 meV/GPa. The thermally annealed\nsample is characterized by at least two phase transitions at 1.1 GPa and 4.2\nGPa, each of which has a different pressure coefficient for PL vibronics. The\nHuang-Rhys factor, a measure of the electron-phonon interaction, is found to\nincrease with increasing pressures signaling a higher geometric relaxation of\nthe electronic states. The Raman peaks harden with increasing pressures; the\nintra-ring C-C stretch frequency at 1600 cm$^{-1}$ has a pressure coefficient\nof 7.2 cm$^{-1}$/GPa and exhibits asymmetric line shapes at higher pressures,\ncharacteristic of a strong electron-phonon interaction. The optical properties\nof PF8 under high pressure are further contrasted with those of a branched side\nchain substituted PF.",
        "positive": "Computing the Helmholtz Capacitance of Charged Insulator-Electrolyte\n  Interfaces from the Supercell Polarization: Supercell modelling of an electrical double layer (EDL) at electrified\nsolid-electrolyte interfaces is a challenge. The net polarization of EDLs\narising from the fixed chemical composition setup leads to uncompensated EDLs\nunder periodic boundary condition and convolutes the calculation of the\nHelmholtz capacitance [Zhang and Sprik, Phys. Rev. B, 94, 245309 (2016)]. Here\nwe provide a new formula based on the supercell polarization at zero electric\nfield $\\bar{E} = 0$ (i.e. standard Ewald boundary condition) to calculate the\nHelmholtz capacitance of charged insulator-electrolyte interfaces and validate\nit using atomistic simulations. Results are shown to be independent of the\nsupercell size. This formula gives a shortcut to compute the Helmholtz\ncapacitance without locating the zero net charge state of EDL and applies\ndirectly to any standard molecular dynamics code where the electrostatic\ninteractions are treated by the Ewald summation or its variants."
    },
    {
        "anchor": "Role of Micellar Entanglement Density on Kinetics of Shear Banding Flow\n  Formation: We investigate the effects of micellar entanglement number on the kinetics of\nshear banding flow formation in a Taylor-Couette flow. Three sets of wormlike\nmicellar solutions, each set with a similar fluid elasticity and\nzero-shear-rate viscosity, but with varying entanglement densities, are studied\nunder start-up of steady shear. Our experiments indicate that in the set with\nthe low fluid elasticity, the transient shear banding flow is characterized by\nthe formation of a transient flow reversal in a range of entanglement\ndensities. Outside of this range, the transient flow reversal is not observed.\nFor the sets of medium and high elasticities, the transient flow reversals\nexist for relatively small entanglement densities, and disappear for large\nentanglement densities. Our analysis shows that wall slip and elastic\ninstabilities do not affect the transient flow feature. We identify a\ncorrelation between micellar entanglement number, the width of the stress\nplateau, and the extent of the transient flow reversal. As the micellar\nentanglement number increases, the width of the stress plateau first increases,\nthen, at a higher micellar entanglement number, plateau width decreases.\nTherefore, we hypothesize that the transient flow reversal is connected to the\nmicellar entanglement number through the width of the stress plateau.",
        "positive": "Self-diffusion of rod-like viruses in the nematic phase: We measure the self-diffusion of colloidal rod-like virus {\\it fd} in an\nisotropic and nematic phase. A low volume fraction of viruses are labelled with\na fluorescent dye and dissolved in a background of unlabelled rods. The\ntrajectories of individual rods are visualized using fluorescence microscopy\nfrom which the diffusion constant is extracted. The diffusion parallel\n($D_{\\parallel}$) and perpendicular ($D_{\\perp}$) to the nematic director is\nmeasured. The ratio ($D_{\\parallel}/D_{\\perp}$) increases monotonically with\nincreasing virus concentration. Crossing the isotropic-nematic phase boundary\nresults in increase of $D_{\\parallel}$ and decrease of $D_{\\perp}$ when\ncompared to the diffusion in the isotropic phase ($D_{iso}$)."
    },
    {
        "anchor": "Block copolymer-nanorod co-assembly in thin films: effects of rod-rod\n  interaction and confinement: Simulations and experiments of nanorods (NRs) show that co-assembly with\nblock copolymer (BCP) melts leads to the formation of a superstructure of\nside-to-side NRs perpendicular to the lamellar axis. A mesoscopic model is\nvalidated against scanning electron microscopy (SEM) images of CdSe NRs mixed\nwith polystyrene-block-poly(methyl methacrylate). It is then used to study the\nco-assembly of anisotropic nanoparticles (NPs) with a length in the same order\nof magnitude as the lamellar spacing. The phase diagram of BCP/NP is explored\nas well as the time evolution of the NR. NRs that are slightly larger than the\nlamellar spacing are found to rotate and organise side-to-side with a tilted\norientation with respect to the interface. Strongly interacting NPs are found\nto dominate the co-assembly while weakly interacting nanoparticles are less\nprone to form aggregates and tend to form well-ordered configurations.",
        "positive": "Unravelling the role of phoretic and hydrodynamic interactions in active\n  colloidal suspensions: Active fluids comprise a variety of systems composed of elements immersed in\na fluid environment which can convert some form of energy into directed motion;\nas such they are intrinsically out-of-equilibrium in the absence of any\nexternal forcing. A fundamental problem in the physics of active matter\nconcerns the understanding of how the characteristics of the autonomous\npropulsion and agent-agent interactions determine the collective dynamics of\nthe system. We study numerically suspensions of self-propelled diffusiophoretic\ncolloids, in (quasi)-2d configurations, accounting for both dynamically\nresolved solute-mediated phoretic interactions and solvent-mediated\nhydrodynamic interactions. Our results show that the system displays different\nscenarios at changing the colloid-solute affinity and it develops a cluster\nphase in the chemoattractive case. We study the statistics of cluster sizes and\ncluster morphologies for different magnitudes of colloidal activity. Finally,\nwe provide evidences that hydrodynamics plays a relevant role in the\naggregation kinetics and cluster morphology, significantly hindering the\ncluster growth."
    },
    {
        "anchor": "Customizing mesoscale self-assembly with 3D printing: Self-assembly due to capillary forces is a common method for generating 2D\nmesoscale structures from identical floating particles at the liquid-air\ninterface. Designing building blocks to obtain a desired mesoscopic structure\nis a scientific challenge. We show herein that it is possible to shape the\nparticles with a low cost 3D printer, for composing specific mesoscopic\nstructures. Our method is based on the creation of capillary multipoles\ninducing either attractive or repulsive forces. Since capillary interactions\ncan be downscaled, our method opens new ways to low cost microfabrication.",
        "positive": "Clustering of microswimmers: Interplay of shape and hydrodynamics: The spatiotemporal dynamics in systems of active self-propelled particles is\ncontrolled by the propulsion mechanism in combination with various direct\ninteractions, such as steric repulsion, hydrodynamics, and chemical fields.\nYet, these direct interactions are typically anisotropic, and come in different\n'flavors', such as spherical and elongated particle shapes for steric\nrepulsion, pusher and puller flow fields for hydrodynamics, etc. The\ncombination of the various aspects is expected to lead to new emergent\nbehavior. However, it is a priori not evident whether shape and hydrodynamics\nact synergistically or antagonistically to generate motility-induced clustering\n(MIC) and phase separation (MIPS). We employ a model of prolate spheroidal\nmicroswimmers - called squirmers - in quasi-two-dimensional confinement to\naddress this issue by mesoscale hydrodynamic simulations. For comparison,\nnon-hydrodynamic active Brownian particles (ABPs) are considered to elucidate\nthe contribution of hydrodynamic interactions on MIC and MIPS. For spherical\nparticles, the comparison between ABP and hydrodynamic-squirmer ensembles\nreveals a suppression of MIPS due to hydrodynamic interactions. The fundamental\ndifference between ABPs and squirmers is attributed to an increased\nreorientation of squirmers by hydrodynamic torques during their collisions. In\ncontrast, for elongated squirmers, hydrodynamics interactions enhance MIPS.\nThus, hydrodynamic interactions show opposing effects on MIPS for spherical and\nelongated microswimmers."
    },
    {
        "anchor": "Superhydrophobic frictions: Contrasting with its sluggish behavior on standard solids, water is extremely\nmobile on superhydrophobic materials, as shown for instance by the continuous\nacceleration of drops on tilted water-repellent leaves. For much longer\nsubstrates, however, drops reach a terminal velocity that results from a\nbalance between weight and friction, allowing us to question the nature of this\nfriction. We report that the relationship between force and terminal velocity\nis non-linear. This is interpreted by showing that classical sources of\nfriction are minimized, so that the aerodynamical resistance to motion becomes\ndominant, which eventually explains the matchless mobility of water. Our\nresults are finally extended to viscous liquids, also known to be unusually\nquick on these materials.",
        "positive": "Parametric generation of second sound in superfluid helium: linear\n  stability and nonlinear dynamics: We report the experimental studies of a parametric excitation of a second\nsound (SS) by a first sound (FS) in a superfluid helium in a resonance cavity.\nThe results on several topics in this system are presented: (i) The linear\nproperties of the instability, namely, the threshold, its temperature and\ngeometrical dependencies, and the spectra of SS just above the onset were\nmeasured. They were found to be in a good quantitative agreement with the\ntheory. (ii) It was shown that the mechanism of SS amplitude saturation is due\nto the nonlinear attenuation of SS via three wave interactions between the SS\nwaves. Strong low frequency amplitude fluctuations of SS above the threshold\nwere observed. The spectra of these fluctuations had a universal shape with\nexponentially decaying tails. Furthermore, the spectral width grew continuously\nwith the FS amplitude. The role of three and four wave interactions are\ndiscussed with respect to the nonlinear SS behavior. The first evidence of\nGaussian statistics of the wave amplitudes for the parametrically generated\nwave ensemble was obtained. (iii) The experiments on simultaneous pumping of\nthe FS and independent SS waves revealed new effects. Below the instability\nthreshold, the SS phase conjugation as a result of three-wave interactions\nbetween the FS and SS waves was observed. Above the threshold two new effects\nwere found: a giant amplification of the SS wave intensity and strong resonance\noscillations of the SS wave amplitude as a function of the FS amplitude.\nQualitative explanations of these effects are suggested."
    },
    {
        "anchor": "Mechanical response functions of finite temperature Bose-Einstein\n  Condensates: Using the Liouville space framework developed in nonlinear optics we\ncalculate the linear response functions and susceptibilities of Bose-Einstein\ncondensates (BEC) subject to an arbitrary mechanical force. Distinct signatures\nof the dynamics of finite temperature BEC are obtained by solving the\nHartree-Fock-Bogoliubov theory. Numerical simulations of the position dependent\nlinear response functions of one dimensional trapped BEC in the time and the\nfrequency domains are presented.",
        "positive": "Collective dynamics of dipolar and multipolar colloids: from passive to\n  active systems: This article reviews recent research on the collective dynamical behavior of\ncolloids with dipolar or multipolar interactions. Indeed, whereas equilibrium\nstructures and static self-assembly of such systems are now rather well\nunderstood, the past years have seen an explosion of interest in understanding\ndynamicals aspects, from the relaxation dynamics of strongly correlated dipolar\nnetworks over systems driven by time-dependent, electric or magnetic fields, to\npattern formation and dynamical control of active, self-propelled systems.\nUnraveling the underlying mechanisms is crucial for a deeper understanding of\nself-assembly in and out of equilibrium and the use of such particles as\nfunctional devices. At the same time, the complex dynamics of dipolar colloids\nposes challenging physical questions and puts forward their role as model\nsystems for nonlinear behavior in condensed matter physics. Here we attempt to\ngive an overview of these developments, with an emphasis on theoretical and\nsimulation studies."
    },
    {
        "anchor": "Global self$-$similarity of dense granular flow in hopper: the role of\n  hopper width: The influence of hopper width on the dense granular flow in a two-dimensional\nhopper is investigated by experiments and simulations. The flow rate remains\nconstant for larger hopper width, while a slight decrease of hopper width\nresults in a significant increase in the flow rate for smaller hopper width.\nBoth Beverloo's and Janda's formula are found to describe relation between the\nflow rate and outlet size well. The flow properties exhibit a local\nself$-$similarity supporting the arguments of the Beverloo's and Janda's\nhypotheses. Importantly, global self$-$similarity is observed, indicating a\nflow state transition between the mass flow in the regions far form the outlet\nand the funnel flow in the regions around the outlet. A reduction in silo width\nleads to a significant increase of grain velocity and a decrease in the\ntransition height, resulting in an increase of flow rate. The results,\nincluding flow rate, grain velocity, and transition height, can be described in\nan exponential formula with respect to the silo width.",
        "positive": "Random, blocky and alternating ordering in supramolecular polymers of\n  chemically bidisperse monomers: As a first step to understanding the role of molecular or chemical\npolydispersity in self-assembly, we put forward a coarse-grained model that\ndescribes the spontaneous formation of quasi-linear polymers in solutions\ncontaining two self-assembling species. Our theoretical framework is based on a\ntwo-component self-assembled Ising model in which the bidispersity is\nparameterized in terms of the strengths of the binding free energies that\ndepend on the monomer species involved in the pairing interaction. Depending\nupon the relative values of the binding free energies involved, different\nmorphologies of assemblies that include both components are formed, exhibiting\nparamagnetic-, ferromagnetic- or anti ferromagnetic-like order,i.e., random,\nblocky or alternating ordering of the two components in the assemblies.\nAnalyzing the model for the case of ferromagnetic ordering, which is of most\npractical interest, we find that the transition from conditions of minimal\nassembly to those characterized by strong polymerization can be described by a\ncritical concentration that depends on the concentration ratio of the two\nspecies. Interestingly, the distribution of monomers in the assemblies is\ndifferent from that in the original distribution, i.e., the ratio of the\nconcentrations of the two components put into the system. The monomers with a\nsmaller binding free energy are more abundant in short assemblies and monomers\nwith a larger binding affinity are more abundant in longer assemblies. Under\ncertain conditions the two components congregate into separate supramolecular\npolymeric species and in that sense phase separate. We find strong deviations\nfrom the expected growth law for supramolecular polymers even for modest\namounts of a second component, provided it is chemically sufficiently distinct\nfrom the main one."
    },
    {
        "anchor": "Shear banding in large amplitude oscillatory shear (LAOStrain and\n  LAOStress) of soft glassy materials: We study theoretically shear banding in soft glassy materials subject to\nlarge amplitude time-periodic shear flows, considering separately the protocols\nof large amplitude oscillatory shear strain, large amplitude square or\ntriangular or sawtooth strain rate, and large amplitude oscillatory shear\nstress. In each case, we find shear banding to be an important part of the\nmaterial's flow response for a broad range of values of the frequency $\\omega$\nand amplitude of the imposed oscillation. Crucially, and highly\ncounterintuitively, in the glass phase this persists even to the lowest\nfrequencies accessible numerically (that seems consistent with it persisting\neven when $\\omega\\to 0$), although the soft glassy rheology model we use has an\nunderlying monotonic constitutive curve of shear stress as a function of shear\nrate, and is therefore unable to support shear banding as its steady state\nresponse at constant shear rate. We attribute this to the repeated competition,\nwithin each flow cycle, of glassy aging and flow rejuvenation. Besides\nreporting significant banding in the glass phase, where the flow curve has a\nyield stress, we also observe it at noise temperatures just above the glass\npoint, where the flow curve is of power law fluid form. Thus, our results\nsuggest a predisposition to shear banding in flows of even extremely slow\ntime-variation, for both aging yield stress fluids, and for power law fluids\nwith sluggish relaxation timescales. We show that shear banding can have a\npronounced effect on the shape of the Lissajous-Bowditch curves that are\ncommonly used to fingerprint complex fluids rheologically. We therefore counsel\ncaution in seeking to compute such curves calculations that impose upfront a\nhomogeneous shear flow, discarding the possibility of banding. We also analyze\nthe stress response to the imposed strain waveforms in terms of a `sequence of\nphysical processes'.",
        "positive": "Collective steady-state patterns of swarmalators with finite-cutoff\n  interaction distance: We study the steady-state patterns of population of the coupled oscillators\nthat sync and swarm, where the interaction distances among oscillators have\nfinite-cutoff in interaction distance. We examine how the static patterns known\nin the infinite-cutoff are reproduced or deformed, and explore a new static\npattern that does not appear until a finite-cutoff is considered. All\nsteady-state patterns of the infinite-cutoff, static sync, static async, and\nstatic phase wave are respectively repeated in space for proper finite-cutoff\nranges. Their deformation in shape and density takes place for the other\nfinite-cutoff ranges. Bar-like phase wave states are observed, which has not\nbeen the case for the infinite-cutoff. All the patterns are investigated via\nnumerical and theoretical analysis."
    },
    {
        "anchor": "The structural order of protein hydration water: The ability of water to dissolve biomolecules is crucial for our life. It has\nbeen shown that protein has a profound effect on the behavior of water in its\nhydration shell, which in turn affects the structure and function of the\nprotein. However, there is still no consensus on whether protein promotes or\ndestroys the structural order of water in its hydration shell until today,\nbecause of the lack of proper structural descriptor incorporating hydrogen-bond\n(H-bond) information for water at the protein/water interface. Here we\nperformed all-atom molecular dynamics simulations of lysozyme protein in water\nand analyzed the H-bond structure of protein hydration water by using a newly\ndeveloped structural descriptor. We find that the protein promotes local\nstructural ordering of the hydration water while has a negligible effect on the\nstrength of individual H-bond. These findings are fundamental to the structure\nand function of biomolecules and provide new insights into the hydration of\nprotein in water.",
        "positive": "Stripes of Partially Fluorinated Alkyl Chains: Dipolar Langmuir\n  Monolayers: Stripe-like domains of Langmuir monolayers formed by surfactants with\npartially fluorinated lipid anchors (F-alkyl lipids) are observed at the\ngas-liquid phase coexistence. The average periodicity of the stripes, measured\nby fluorescence microscopy, is in the micrometer range, varying between 2 and 8\nmicrons. The observed stripe-like patterns are stabilized due to dipole-dipole\ninteractions between terminal -CF3 groups. These interactions are particularly\nstrong as compared with non-fluorinated lipids due to the low dielectric\nconstant of the surrounding media (air). These long-range dipolar interactions\ntend to elongate the domains, in contrast to the line tension that tends to\nminimize the length of the domain boundary. This behavior should be compared\nwith that of the lipid monolayer having alkyl chains, and which form spherical\nmicro-domains (bubbles) at the gas-liquid coexistence. The measured stripe\nperiodicity agrees quantitatively with a theoretical model. Moreover, the\nreduction in line tension by adding traces (0.1 mol fraction) of cholesterol\nresults, as expected, in a decrease in the domain periodicity."
    },
    {
        "anchor": "Growth modes of quasicrystals: The growth of quasicrystals, i.e., aperiodic structures with long-range\norder, seeded from the melt is investigated using a dynamical phase field\ncrystal model. Depending on the thermodynamic conditions, two different growth\nmodes are detected, namely defect-free growth of the stable quasicrystal and a\nmode dominated by phasonic flips which are incorporated as local defects into\nthe grown structure such that random tiling-like ordering emerges. The latter\ngrowth mode is unique to quasicrystals and can be verified in experiments on\none-component mesoscopic systems.",
        "positive": "Probing a self-assembled fd virus membrane with a microtubule: The self-assembly of highly anisotropic colloidal particles leads to a rich\nvariety of morphologies, whose properties are just beginning to be understood.\nThis article uses computer simulations to probe a particle-scale perturbation\nof a commonly studied colloidal assembly, a monolayer membrane composed of\nrodlike fd viruses in the presence of a polymer depletant. Motivated by\nexperiments currently in progress, we simulate the interaction between a\nmicrotubule and a monolayer membrane as the microtubule \"pokes\" and penetrates\nthe membrane face-on. Both the viruses and the microtubule are modeled as hard\nspherocylinders of the same diameter, while the depletant is modeled using\nghost spheres. We find that the force exerted on the microtubule by the\nmembrane is zero either when the microtubule is completely outside the membrane\nor when it has fully penetrated the membrane. The microtubule is initially\nrepelled by the membrane as it begins to penetrate but experiences an\nattractive force as it penetrates further. We assess the roles played by\ntranslational and rotational fluctuations of the viruses and the osmotic\npressure of the polymer depletant. We find that rotational fluctuations play a\nmore important role than the translational ones. The dependence on the osmotic\npressure of the depletant of the width and height of the repulsive barrier and\nthe depth of the attractive potential well is consistent with the assumed\ndepletion-induced attractive interaction between the microtubule and viruses.\nWe discuss the relevance of these studies to the experimental investigations.\n\\end{abstract}"
    },
    {
        "anchor": "Bubble-bound state of triple-stranded DNA: Efimov Physics in DNA with\n  repulsion: The presence of a thermodynamic phase of a three-stranded DNA, namely, a\nmixed phase of bubbles of two bound strands and a single one, is established\nfor large dimensions ($d\\geq 5$) by using exact real space renormalization\ngroup (RG) transformations and exact computations of specific heat for finite\nlength chains. Similar exact computations for the fractal Sierpinski gasket of\ndimension $d<2$ establish the stability of the phase in presence of repulsive\nthree chain interaction. In contrast to the Efimov DNA, where three strands are\nbound though no two are bound, the mixed phase appears on the bound side of the\ntwo chain melting temperature. Both the Efimov-DNA and the mixed phase are\nformed due to strand exchange mechanism.",
        "positive": "Forcing and Velocity Correlations in a Vibrated Granular Monolayer: The role of forcing on the dynamics of a vertically shaken granular monolayer\nis investigated. Using a flat plate, surprising negative velocity correlations\nare measured. A mechanism for this anti-correlation is proposed with support\nfrom both experimental results and molecular dynamics simulations. Using a\nrough plate, velocity correlations are positive, and the velocity distribution\nevolves from a gaussian at very low densities to a broader distribution at high\ndensities. These results are interpreted as a balance between stochastic\nforcing, interparticle collisions, and friction with the plate."
    },
    {
        "anchor": "Experiments and Discrete Element Simulation of the Dosing of Cohesive\n  Powders in a Simplified Geometry: We perform experiments and discrete element simulations on the dosing of\ncohesive granular materials in a simplified geometry. The setup is a simplified\ncanister box where the powder is dosed out of the box through the action of a\nconstant-pitch screw feeder connected to a motor. A dose consists of a rotation\nstep followed by a period of rest before the next dosage.\n  From the experiments, we report on the operational performance of the dosing\nprocess through a variation of dosage time, coil pitch and initial powder mass.\nWe find that the dosed mass shows an increasing linear dependence on the dosage\ntime and rotation speed. In contrast, the mass output from the canister is not\ndirectly proportional to an increase/decrease in the number coils. By\ncalibrating the interparticle friction and cohesion, we show that DEM\nsimulation can quantitatively reproduce the experimental findings for smaller\nmasses but also overestimate arching and blockage. With appropriate\nhomogenization tools, further insights into microstructure and macroscopic\nfields can be obtained.\n  This work shows that particle scaling and the adaptation of particle\nproperties is a viable approach to overcome the untreatable number of particles\ninherent in experiments with fine, cohesive powders and opens the gateway to\nsimulating their flow in more complex geometries.",
        "positive": "Effective interactions between fluid membranes: A self-consistent theory is proposed for the general problem of interacting\nundulating fluid membranes subject to the constraint that they do not\ninterpenetrate. We implement the steric constraint via an exact functional\nintegral representation, and through the use of a saddle-point approximation\ntransform it into a novel effective steric potential. The steric potential is\nfound to consist of two contributions: one generated by zero mode fluctuations\nof the membranes, and the other by thermal bending fluctuations. For membranes\nof cross-sectional area $S$, we find that the bending fluctuation part scales\nwith the inter-membrane separation $d$ as $d^{-2}$ for $d \\ll \\sqrt{S}$, but\ncrosses over to $d^{-4}$ scaling for $d \\gg \\sqrt{S}$, whereas the zero mode\npart of the steric potential always scales as $d^{-2}$. For membranes\ninteracting exclusively via the steric potential, we obtain closed-form\nexpressions for the effective interaction potential and for the rms undulation\namplitude $\\sigma$, which becomes small at low temperatures $T$ and/or large\nbending stiffnesses $\\kappa$. Moreover, $\\sigma$ scales as $d$ for $d \\ll\n\\sqrt{S}$, but saturates at $\\sqrt{k_{{\\rm B}} T S/\\kappa}$ for $d \\gg\n\\sqrt{S}$. In addition, using variational Gaussian theory, we apply our\nself-consistent treatment to study inter-membrane interactions subject to three\ndifferent types of potential: (i)~the Moreira-Netz potential for a pair of\nstrongly charged membranes with an intervening solution of multivalent\ncounterions, (ii)~an attractive square well, (iii)~the Morse potential, and\n(iv)~a combination of hydration and van der Waals interactions."
    },
    {
        "anchor": "A unified framework for non-Brownian suspension flows and soft amorphous\n  solids: While the rheology of non-Brownian suspensions in the dilute regime is\nwell-understood, their behavior in the dense limit remains mystifying. As the\npacking fraction of particles increases, particle motion becomes more\ncollective, leading to a growing length scale and scaling properties in the\nrheology as the material approaches the jamming transition. There is no\naccepted microscopic description of this phenomenon. However, in recent years\nit has been understood that the elasticity of simple amorphous solids is\ngoverned by a critical point, the unjamming transition where the pressure\nvanishes, and where elastic properties display scaling and a diverging length\nscale. The correspondence between these two transitions is at present unclear.\nHere we show that for a simple model of dense flow, which we argue captures the\nessential physics near the jamming threshold, a formal analogy can be made\nbetween the rheology of the flow and the elasticity of simple networks. This\nanalogy leads to a new conceptual framework to relate microscopic structure to\nrheology. It enables us to define and compute numerically normal modes and a\ndensity of states. We find striking similarities between the density of states\nin flow, and that of amorphous solids near unjamming: both display a plateau\nabove some frequency scale \\omega* ~ |z_c-z|, where z is the coordination of\nthe network of particles in contact, z_c = 2D where D is the spatial dimension.\nHowever, a spectacular difference appears: the density of states in flow\ndisplays a single mode at another frequency scale \\omega_{min} << \\omega*\ngoverning the divergence of the viscosity.",
        "positive": "Morphology of active deformable 3D droplets: We numerically investigate the morphology and disclination line dynamics of\nactive nematic droplets in three dimensions. Although our model only\nincorporates the simplest possible form of achiral active stress, active\nnematic droplets display an unprecedented range of complex morphologies. For\nextensile activity finger-like protrusions grow at points where disclination\nlines intersect the droplet surface. For contractile activity, however, the\nactivity field drives cup-shaped droplet invagination, run-and-tumble motion or\nthe formation of surface wrinkles. This diversity of behaviour is explained in\nterms of an interplay between active anchoring, active flows and the dynamics\nof the motile dislocation lines. We discuss our findings in the light of\nbiological processes such as morphogenesis, collective cancer invasion and the\nshape control of biomembranes, suggesting that some biological systems may\nshare the same underlying mechanisms as active nematic droplets."
    },
    {
        "anchor": "Topologically Driven Swelling of a Polymer Loop: Numerical studies of the average size of trivially knotted polymer loops with\nno excluded volume are undertaken. Topology is identified by Alexander and\nVassiliev degree 2 invariants. Probability of a trivial knot, average gyration\nradius, and probability density distributions as functions of gyration radius\nare generated for loops of up to N=3000 segments. Gyration radii of trivially\nknotted loops are found to follow a power law similar to that of self avoiding\nwalks consistent with earlier theoretical predictions.",
        "positive": "Polymer escape from a confining potential: The rate of escape of polymers from a two-dimensionally confining potential\nwell has been evaluated using self-avoiding as well as ideal chain\nrepresentations of varying length, up to 80 beads. Long timescale Langevin\ntrajectories were calculated using the path integral hyperdynamics method to\nevaluate the escape rate. A minimum is found in the rate for self-avoiding\npolymers of intermediate length while the escape rate decreases monotonically\nwith polymer length for ideal polymers. The increase in the rate for long,\nself-avoiding polymers is ascribed to crowding in the potential well which\nreduces the free energy escape barrier. An effective potential curve obtained\nusing the centroid as an independent variable was evaluated by thermodynamic\naveraging and Kramers rate theory then applied to estimate the escape rate.\nWhile the qualitative features are well reproduced by this approach, it\nsignificantly overestimates the rate, especially for the longer polymers. The\nreason for this is illustrated by constructing a two-dimensional effective\nenergy surface using the radius of gyration as well as the centroid as\ncontrolled variables. This shows that the description of a transition state\ndividing surface using only the centroid fails to confine the system to the\nregion corresponding to the free energy barrier and this problem becomes more\npronounced the longer the polymer is. A proper definition of a transition state\nfor polymer escape needs to take into account the shape as well as the location\nof the polymer."
    },
    {
        "anchor": "Nonlinear Viscoelastic Modeling of Adhesive Failure for Polyacrylate\n  Pressure-Sensitive Adhesives: We investigate experimentally the adherence energy $\\Gamma$ of model\npolyacrylate Pressure Sensitive Adhesives (PSAs) with combined large strain\nrheological measurements in uniaxial extension and an instrumented peel test.\nWe develop a nonlinear model for such peel test which captures the dependence\nof $\\Gamma(V)$ with peeling rate $V$ revealing the key role played by the\nextensional rheology. Our model explains in particular why traditional linear\nviscoelastic approaches correctly predict the slope of $\\Gamma(V)$ curves for\nsufficiently elastic PSAs characterized by a simple rate-independent debonding\ncriterion. However, for more viscoelastic adhesives, we identified a more\ncomplex rate-dependent debonding criterion yielding a significant modification\nof the $\\Gamma(V)$ curves, an effect that has been largely overlooked so far.\nThis investigation opens the way towards the understanding of fibrils\ndebonding, which is the main missing block to predict the adherence of PSAs.",
        "positive": "Pattern Selection: Determined by Symmetry and Modifiable by Long-Range\n  Effects: We consider Saffman-Taylor channel flow without surface tension on a\nhigh-pressure driven interface, but modify the usual infinite-fluid in\ninfinite-channel configuration. Here we include the treatment of efflux by\nconsidering a finite connected body of fluid in an arbitrarily long channel,\nwith its second free interface the efflux of this configuration. We show that\nthere is a uniquely determined translating solution for the driven interface,\nwhich is exactly the 1/2 width S-T solution, following from correct symmetry\nfor a finite channel flow. We establish that there exist no perturbations about\nthis solution corresponding to a finger propagating with any other width:\nSelection is unique and isolated. The stability of this solution is anomalous,\nin that all freely impressible perturbations are stabilities, while unstable\nmodes request power proportional to their strength from the external agencies\nthat drive the flow, and so, in principle, are experimentally controllable.\nThis is very different from the behavior of the usual infinite fluid: The limit\nof infinite length is singular, and not that of the literature. We argue that\nsurface tension on the efflux interface decreases the finger-width by the ratio\nof its surface tension to velocity of the high-pressure tip. The perturbation\ntheory created here to deal with transport between two free boundaries is novel\nand dependent upon a remarkable symmetry."
    },
    {
        "anchor": "Bogomol'nyi Decomposition for Vesicles of Arbitrary Genus: We apply the Bogomol'nyi technique, which is usually invoked in the study of\nsolitons or models with topological invariants, to the case of elastic energy\nof vesicles. We show that spontaneous bending contribution caused by any\ndeformation from metastable bending shapes falls in two distinct topological\nsets: shapes of spherical topology and shapes of non-spherical topology\nexperience respectively a deviatoric bending contribution a la Fischer and a\nmean curvature bending contribution a la Helfrich. In other words, topology may\nbe considered to describe bending phenomena. Besides, we calculate the bending\nenergy per genus and the bending closure energy regardless of the shape of the\nvesicle. As an illustration we briefly consider geometrical frustration\nphenomena experienced by magnetically coated vesicles.",
        "positive": "Stability of liquid crystalline phases in the phase-field-crystal model: The phase-field-crystal model for liquid crystals is solved numerically in\ntwo spatial dimensions. This model is formulated with three position-dependent\norder parameters, namely the reduced translational density, the local nematic\norder parameter, and the mean local direction of the orientations. The\nequilibrium free-energy functional involves local powers of the order\nparameters up to fourth order, gradients of the order parameters up to fourth\norder, and different couplings between the order parameters. The stable phases\nof the equilibrium free-energy functional are calculated for various coupling\nparameters. Among the stable liquid-crystalline states are the isotropic,\nnematic, columnar, smectic A, and plastic crystalline phases. The plastic\ncrystals can have triangular, square, and honeycomb lattices and exhibit\norientational patterns with a complex topology involving a sublattice with\ntopological defects. Phase diagrams were obtained by numerical minimization of\nthe free-energy functional. Their main features are qualitatively in line with\nmuch simpler one-mode approximations for the order parameters."
    },
    {
        "anchor": "Multivalent cation induced attraction of anionic polymers by\n  like-charged pores: The efficiency of nanopore-based polymer sensing devices depends on the fast\ncapture of anionic polyelectrolytes by negatively charged pores. This requires\nthe cancellation of the electrostatic barrier associated with repulsive\npolymer-pore interactions. We develop a correlation-corrected theory to show\nthat the barrier experienced by the polymer can be efficiently overcome by the\naddition of multivalent cations into the electrolyte solution. Cation\nadsorption into the pore enhances the screening ability of the pore medium with\nrespect to the bulk reservoir which translates into an attractive force on the\npolymer. Beyond a critical multivalent cation concentration, this\ncorrelation-induced attraction overcomes the electrostatic barrier and triggers\nthe adsorption of the polymer by the like-charged pore. It is shown that\nlike-charge polymer-pore attraction is suppressed by monovalent salt but\nenhanced by the membrane charge strength and the pore confinement. Our\npredictions may provide enhanced control over polymer motion in translocation\nexperiments.",
        "positive": "Effective General Relativistic Description of Jamming in Granular Matter: We propose here that certain observational features of granular matter in the\ninfrared limit, exhibiting the phenomenon of {\\it jamming}, arise from an\nunderlying effective general relativistic description. The proposal stems from\nthe assumption (which we justify on physical grounds) that grains in granular\nmatter move freely in an {\\it effective} curved Riemannian space. The\ntermination of their trajectories at the onset of jamming is obtained from the\nfocussing of a converging congruence of geodesics in such a space, as a\nsolution of the Raychaudhuri equation for such congruences. This may happen\nirrespective of whether or not the curvature is sourced by external stresses\n(via an effective Einstein equation), although the properties of the resultant\njammed state solution do differ in the two cases. A definite prediction of this\ngeometrical approach is the negative role played by those trajectories which\ntwist about each other, in reaching the jammed state. The local symmetries of\ngranular interaction, translational and rotational invariance (corresponding to\n`force balance' and `torque balance' in standard force-based approaches to\njamming) are inherent in the effective general relativity framework. A\nrecently-proposed effective elasticity model of the jammed state, based on a\ntensorial variant of standard electrostatics (Vector Charge Theory), is seen to\nbe entirely subsumed within the linearized version of the effective general\nrelativistic description."
    },
    {
        "anchor": "Predicting aggregate morphology of sequence-defined macromolecules with\n  Recurrent Neural Networks: Self-assembly of dilute sequence-defined macromolecules is a complex\nphenomenon in which the local arrangement of chemical moieties can lead to the\nformation of long-range structure. The dependence of this structure on the\nsequence necessarily implies that a mapping between the two exists, yet it has\nbeen difficult to model so far. Predicting the aggregation behavior of these\nmacromolecules is challenging due to the lack of effective order parameters, a\nvast design space, inherent variability, and high computational costs\nassociated with currently available simulation techniques. Here, we accurately\npredict the morphology of aggregates self-assembled from sequence-defined\nmacromolecules using supervised machine learning. We find that regression\nmodels with implicit representation learning perform significantly better than\nthose based on engineered features such as $k$-mer counting, and a\nRecurrent-Neural-Network-based regressor performs the best out of nine model\narchitectures we tested. Furthermore, we demonstrate the high-throughput\nscreening of monomer sequences using the regression model to identify\ncandidates for self-assembly into selected morphologies. Our strategy is shown\nto successfully identify multiple suitable sequences in every test we\nperformed, so we hope the insights gained here can be extended to other\nincreasingly complex design scenarios in the future, such as the design of\nsequences under polydispersity and at varying environmental conditions.",
        "positive": "Self assembled linear polymeric chains with tuneable semiflexibility\n  using isotropic interactions: We propose a two-body spherically symmetric (isotropic) potential such that\nparticles interacting by the potential self assemble into linear semiflexible\npolymeric chains without branching. By suitable control of the potential\nparameters we can control the persistence length of the polymer, and can even\nintroduce a controlled number of branches. Thus we show how to achieve\neffective directional interactions starting from spherically symmetric\npotentials. The self assembled polymers have a exponential distribution of\nchain lengths akin to what is observed for worm-like micellar systems. On\nincreasing particle density the polymeric chains self-organize to an ordered\nline-hexagonal phase where every chain is surrounded by six parallel chains,\nthe transition is first order. On further increase in monomer density, the\norder is destroyed and we get a branched gel like phase. This potential can be\nused to model semi-flexible equilibrium polymers with tunable semiflexibility\nand excluded volume. The use of the potential is computationally cheap and\nhence, can be used to simulate and probe complex micellar dynamics with long\nchains. The potential also gives a plausible method of tuning colloidal\ninteractions in experiments such that one can obtain self-assembling polymeric\nchains made up of colloids and probe polymer dynamics using an optical\nmicroscope."
    },
    {
        "anchor": "Dynamics of Self-Propelled Particles Under Strong Confinement: We develop a statistical theory for the dynamics of non-aligning,\nnon-interacting self-propelled particles confined in a convex box in two\ndimensions. We find that when the size of the box is small compared to the\npersistence length of a particle's trajectory (strong confinement), the\nsteady-state density is zero in the bulk and proportional to the local\ncurvature on the boundary. Conversely, the theory may be used to construct the\nbox shape that yields any desired density distribution on the boundary. When\nthe curvature variations are small, we also predict the distribution of\norientations at the boundary and the exponential decay of pressure as a\nfunction of box size recently observed in 3D simulations in a spherical box.",
        "positive": "Anomalously slow attrition times for asymmetric populations with\n  internal group dynamics: The many-body dynamics exhibited by living objects include group formation\nwithin a population, and the non-equilibrium process of attrition between two\nopposing populations due to competition or conflict. We show analytically and\nnumerically that the combination of these two dynamical processes generates an\nattrition duration T whose nonlinear dependence on population asymmetry x is in\nstark contrast to standard mass-action theories. A minority population\nexperiences a longer survival time than two equally balanced populations,\nirrespective of whether the majority population adopts such internal grouping\nor not. Adding a third population with pre-defined group sizes allows T(x) to\nbe tailored. Our findings compare favorably to real-world observations."
    },
    {
        "anchor": "Coupling disorder in a population of swarmalators: We consider a population of two-dimensional oscillators with random\ncouplings, and explore the collective states. The coupling strength between\noscillators is randomly quenched with two values one of which is positive while\nthe other is negative, and the oscillators can spatially {\\it{move}} depending\non the state variables for phase and position. We find that the system shows\nthe phase transition from the incoherent state to the fully synchronized one at\na proper ratio of the number of positive couplings to the total. The threshold\nis numerically measured, and analytically predicted by the linear stability\nanalysis of the fully synchronized state. It is found that the random couplings\ninduces the long-term state patterns appearing for constant strength. The\noscillators move to the places where the randomly quenched couplings work as if\nannealed. We further observe that the system with mixed randomnesses for\nquenched couplings shows the combination of the deformed patterns\nunderstandable with each annealed averages.",
        "positive": "Curvature-dependent tension and tangential flows at the interface of\n  motility-induced phases: Purely repulsive active particles spontaneously undergo motility-induced\nphase separation (MIPS) into condensed and dilute phases. Remarkably, the\nmechanical tension measured along the interface between these phases is\nnegative. In equilibrium this would imply an unstable interface that wants to\nexpand, but these out-of-equilibrium systems display long-time stability and\nhave intrinsically stiff boundaries. Here, we study this phenomenon in detail\nusing active Brownian particle simulations and a novel frame of reference. By\nshifting from the global (or laboratory) frame to a local frame that follows\nthe dynamics of the phase boundary, we observe correlations between the local\ncurvature of the interface and the measured value of the tension. Importantly,\nour analysis reveals the presence of sustained local tangential motion of\nparticles within a surface layer in both the gas and the dense regions. The\ncombined tangential current in the gas and self-shearing of the surface of the\ndense phase suggest a stiffening interface that redirects particles along\nitself to heal local fluctuations. These currents restore the otherwise wildly\nfluctuating interface through an out-of-equilibrium Marangoni effect. We\ndiscuss the implications of our observations on phenomenological models of\ninterfacial dynamics."
    },
    {
        "anchor": "A stochastic approach to the filling dynamics of a porous medium:\n  full/empty pores duality symmetry and the emergence of Darcy's law: A stochastic approach to the filling dynamics of an open topology porous\nstructure permeated with a perfectly wetting fluid is presented. From the\ndiscrete structure of the disordered voids network with only nearest neighbors\nlinks, we derive the \"microscopic\" (at the pores scale) dynamical equations\ngoverning the filling dynamics of the coupled pores and the fluid pressure\ndynamics. The model yields two fundamental consequences. The first consequence\nregards the emergence of Darcy's law and the dependence of the predicted\npermeability with the voids network topology. The second one is the prediction\nof a diffusive dynamics for the degrees of freedom of the pores filling. These\nequations exhibit a new type of symmetry manifested by their invariance under\nthe full/empty pores duality transformation jointly with the velocity reversal.\nNon-trivial steady non-equilibrium pores filling states are also obtained and\nfound to follow a Fermi-Dirac type law. The analogy with the single occupation\nof lattice sites by fermions is highlighted together with the corresponding\nhole-particle symmetry.",
        "positive": "Connection between fragility, mean-squared displacement and shear\n  modulus in two van der Waals bonded glass-forming liquids: The temperature dependence of the high-frequency shear modulus measured in\nthe kHz range is compared to the mean-squared displacement measured in the\nnanosecond range for the two van der Waals bonded glass-forming liquids cumene\nand 5PPE. This provides an experimental test for the assumption connecting two\nversions of the shoving model for the non-Arrhenius temperature dependence of\nthe relaxation time in glass formers. The two versions of the model are also\ntested directly and both are shown to work well for these liquids."
    },
    {
        "anchor": "(Ir)reversibility in dense granular systems driven by oscillating forces: We use computer simulations to study highly dense systems of granular\nparticles that are driven by oscillating forces. We implement different\ndissipation mechanisms that are used to extract the injected energy. In\nparticular, the action of a simple local Stokes' drag is compared with\nnon-linear and history-dependent frictional forces that act either between\nparticle pairs or between particles and an external container wall. The Stokes'\ndrag leads to particle motion that is periodic with the driving force, even at\nhigh densities around close packing where particles undergo frequent\ncollisions. With the introduction of inter-particle frictional forces this\n\"interacting absorbing state\" is destroyed and particles start to diffuse\naround. By reducing the density of the material we go through another\ntransition to a \"non-interacting\" absorbing state, where particles\nindependently follow the force-induced oscillations without collisions. In the\nsystem with particle-wall frictional interactions this transition has signs of\na discontinuous phase transition. It is accompanied by a diverging relaxation\ntime, but not by a vanishing order parameter, which rather jumps to zero at the\ntransition.",
        "positive": "A Discrete Element Method model for frictional fibers: We present a Discrete Element Method algorithm for the simulation of elastic\nfibers in frictional contacts. The fibers are modeled as chains of cylindrical\nsegments connected to each other by springs taking into account elongation,\nbending and torsion forces. The frictional contacts between the cylinders are\nmodeled using a Cundall and Strack model routinely used in granular material\nsimulations. The physical scales for simulations, the determination and the\ntracking of contacts, and the algorithm are discussed. Tests on different\nsituations involving few or many contact points are presented and compared to\nexperiments or to theoretical predictions."
    },
    {
        "anchor": "Like-charge attraction and opposite-charge decomplexation between\n  polymers and DNA molecules: We scrutinize the effect of polyvalent ions on polymer-DNA interactions. We\nextend a recently developed test charge theory to the case of a stiff polymer\ninteracting with a DNA molecule in an electrolyte mixture. The theory accounts\nfor one-loop level electrostatic correlation effects such as the ionic cloud\ndeformation around the strongly charged DNA molecule as well as image-charge\nforces induced by the low DNA permittivity. Our model can reproduce and explain\nvarious characteristics of the experimental phase diagrams for polymer\nsolutions. First, the addition of polyvalent cations to the electrolyte\nsolution results in the attraction of the negatively charged polymer by the DNA\nmolecule. The glue of the like-charge attraction is the enhanced shielding of\nthe polymer charges by the dense counterion layer at the DNA surface. Secondly,\nthrough the shielding of the DNA-induced electrostatic potential, mono- and\npolyvalent cations of large concentration both suppress the like-charge\nattraction. Within the same formalism, we also predict a new opposite-charge\nrepulsion effect between the DNA molecule and a positively charged polymer. In\nthe presence of polyvalent anions such as sulfate or phosphate, their repulsion\nby the DNA charges leads to the charge screening deficiency of the region\naround the DNA molecule. This translates into a repulsive force that results in\nthe decomplexation of the polymer from DNA. This opposite-charge repulsion\nphenomenon can be verified by current experiments and the underlying mechanism\ncan be beneficial to gene therapeutic applications where the control over\npolymer-DNA interactions is the key factor.",
        "positive": "Molecular Dynamics Study of Polarization Effects on AgI: Three different models of AgI are studied by molecular dynamics simulations.\nThe first one is the rigid ion model (RIM) with the effective pair potential of\nthe Vashishta and Rahman form and the parameterization proposed by Shimojo and\nKobayashi. The other two are polarizable ion models in which the induced\npolarization effects have been added to the RIM effective pair potential. In\none of them (PIM1) only the anions are assumed to be polarizable by the local\nelectric field. In the other one (PIM2s) the silver polarization is also\nincluded, and a short-range overlap induced polarization opposes the\nelectrically induced dipole moments. This short-range polarization is proved to\nbe necessary to avoid overpolarization when both species are assumed to be\npolarizable. The three models reproduce the superionic character of alpha-AgI\nat 573 K and the liquid behavior of molten AgI at 923 K. The averaged spatial\ndistribution of the cations in the alpha-phase obtained for PIM1 appears to be\nin better agreement with experimental data analysis. The PIM1 also reproduces\nthe structure factor prepeak at about 1 reciprocal angstrom observed from\nneutron diffraction data of molten AgI. The three models retain in the liquid\nphase the superionic character of alpha-AgI as the mobility of the cations is\nsignificantly larger than that for the anions. The ionic conductivity for the\npolarizable ion models is in better agreement with experimental data for\nalpha-AgI and molten AgI."
    },
    {
        "anchor": "Deviations from the mean field predictions for the phase behaviour of\n  random copolymers melts: We investigate the phase behaviour of random copolymers melts via large scale\nMonte Carlo simulations. We observe macrophase separation into A and B--rich\nphases as predicted by mean field theory only for systems with a very large\ncorrelation lambda of blocks along the polymer chains, far away from the\nLifshitz point. For smaller values of lambda, we find that a locally\nsegregated, disordered microemulsion--like structure gradually forms as the\ntemperature decreases. As we increase the number of blocks in the polymers, the\nregion of macrophase separation further shrinks. The results of our Monte Carlo\nsimulation are in agreement with a Ginzburg criterium, which suggests that mean\nfield theory becomes worse as the number of blocks in polymers increases.",
        "positive": "Finite size effects in non-equilibrium membrane phase separation: The formation of dynamical clusters of proteins is ubiquitous in cellular\nmembranes and is in part regulated by the recycling of membrane components.\nMean-field models of out-of-equilibrium cluster formation with recycling\npredict a broad cluster size distribution for infinite systems and must be\ncorrected for finite-size effects for small systems such as cellular\norganelles. We show, using stochastic simulations and analytic modelling, that\ntuning the system size is an efficient way to control the size of lateral\nmembrane heterogeneities. We apply these findings to a chain of enzymatic\nreaction sensitive to membrane protein clustering. The reaction efficiency is\nfound to be a non-monotonic function of the system size, and can be optimal for\nsizes comparable to those of cellular organelles."
    },
    {
        "anchor": "Models for the yielding behaviour of amorphous solids: Understanding the mechanical response and failure of solids is of obvious\nimportance in their use as structural materials. The nature of plastic\ndeformation leading to yielding of amorphous solids has been vigorously pursued\nin recent years. Investigations employing both unidirectional and cyclic\ndeformation protocols reveal a strong dependence of yielding behaviour on the\ndegree of annealing. Below a threshold degree of annealing, the nature of\nyielding changes qualitatively, to progressively more discontinuous yielding.\nTheoretical investigations of yielding in amorphous solids have almost\nexclusively focused on yielding under unidirectional deformation, but cyclic\ndeformation reveals several interesting features that remain largely\nun-investigated. Focusing on athermal cyclic deformation, I investigate a\nfamily of models based on an energy landscape description. These models\nreproduce key interesting features observed in simulations, and provide an\ninterpretation for the intriguing presence of a threshold energy.",
        "positive": "Room-temperature ferroelectric nematic liquid crystal showing a large\n  and divergent density: The ferroelectric nematic phase (NF) is a recently discovered phase of matter\nin which the orientational order of the conventional nematic liquid crystal\nstate is augmented with polar order. Atomistic simulations suggest that the\npolar NF phase would be denser than conventional nematics owing to\ncontributions from polar order. Using an oscillating U-tube densitometer, we\nobtain detailed temperature-dependent density values for a selection of\nconventional liquid crystals with excellent agreement with earlier reports.\nHaving demonstrated the validity of our method, we then record density as a\nfunction of temperature for M5, a novel room-temperature ferroelectric nematic\nmaterial. We present the first experimental density data for a NF material as\nwell as density data for a nematic that has not previously been reported. We\nfind that the room-temperature NF material shows a large (>1.3 g cm3) density\nat all temperatures studied, with an increase in density at phase transitions.\nThe magnitude of the increase for the intermediate splay-ferroelectric nematic\n(NX-NF) transition is an order of magnitude smaller than the isotropic-nematic\n(I-N) transition. Present results may be typical of ferroelectric nematic\nmaterials, potentially guiding material development, and is especially relevant\nfor informing ongoing studies into this emerging class of materials."
    },
    {
        "anchor": "Crack Formation in Laponite Gel under AC Fields: Crack formation patterns in laponite gel are known to be strongly affected by\nDC electric fields. We show that AC fields produce equally remarkable patterns\nin a radially symmetric set-up. The character of the pattern depends crucially\non the field strength. A significant feature observed is the bending of radial\ncracks, with the curvature increasing as field strength is increased. Fields of\n20 to 70 V have been applied and several features of the resulting patterns\nquantified. Striations on the fracture surfaces and crack speeds are also\nstudied.",
        "positive": "A method for estimating the cooperativity length in polymers: The problem of estimating the size of the cooperatively rearranging regions\n(CRRs) in supercooled polymeric melts from the analysis of the $\\alpha$-process\nin ordinary relaxation experiments is addressed. The system is treated with the\ncanonical formalism as an ensemble of CRRs, which are described by a stationary\ndistribution relative to the rearrangement energy threshold. The process\nwhereby a CRR changes its configuration is viewed as consisting of two distinct\nsteps: a reduced number of monomers reaches initially an activated state\nallowing for some local rearrangement; then, the regression of the energy\nfluctuation may take place through the configurational degrees of freedom, thus\nallowing for further rearrangements on larger length-scales. The latter are\nindeed those to which the well known Donth's scheme refers. Two main regimes\nare envisaged, depending on wether the role played by the configurational\ndegrees of freedom in the regression of the energy fluctuation is significant\nor not. It is argued that the latter case is related to the occurrence of an\narrhenian dependence of the central relaxation time. Data of the literature are\nrediscussed within this new framework."
    },
    {
        "anchor": "On the equivocal nature of the mass absorption curves: The idea behind the research presented is based upon apparently contradictory\nexperimental results obtained here by means of photoacoustics modalities for\nthe same drug donor/acceptor membrane system, serving as a surrogate for a\ntransdermal delivery system. The first modality allowed for the monitoring of\nthe total amount of mass uptake (m(t)-type data), while the second technique\nallowed for the quantification of time-dependent concentration distribution\nwithin the acceptor membrane (c(x,t)-type data). Despite of a very good\nagreement between the m(t) data and the 1st-order uptake fitting model\n(standard Fickian diffusion with constant source boundary condition), the\nstandard approach failed during the c(x,t) data analysis. The results led to\nthe analysis of the interfacial transfer contribution to the overall mass\ntransfer efficiency, which eventually allowed to question reliability of the\nm(t) data analysis for the determination and quantification of the mass\ntransport parameters. A more detailed analysis of the c(x,t) by means of the\nnewly introduced transport rate number parameter revealed, that the mass uptake\nby the acceptor is almost equally influenced by interfacial and bulk transport\nprocesses. The analyses performed were translated into a model-free\ncharacteristic times, i.e. parameters common for any of the model scheme used.",
        "positive": "Terahertz absorption of lysozyme in solution: Absorption of radiation by solution is described by the solution dielectric\nconstant and can be viewed as a specific application of the dielectric theory\nof solutions. For ideal solutions, the dielectric boundary value problem\nseparates the polar response into the polarization of the void in the liquid\ncreated by the solute and the response of the solute dipole. In the case of a\nprotein as a solute, its nuclear dynamics do not project on significant\nfluctuations of the dipole moment in the terahertz domain of frequencies and\nthe protein dipole can be viewed as dynamically frozen. Absorption of radiation\nthen reflects the interfacial polarization. Here we apply an analytical theory\nand computer simulation to absorption of radiation by ideal solutions of\nlysozyme. Comparison with experiment shows that Maxwell electrostatics fails to\ndescribe the polarization of the protein-water interface and the \"Lorentz\nvoid\", which does not anticipate polarization of the solute void by the\nexternal field (no surface charges), better represents the data. An analytical\ntheory for the slope of the solution absorption against the volume fraction of\nthe solute is formulated in terms of the cavity field response function. It is\ncalculated from molecular dynamics simulations in good agreement with\nexperiment. The protein hydration shell emerges as a separate sub-ensemble,\nwhich collectively is not described by the standard electrostatics of\ndielectrics."
    },
    {
        "anchor": "Physics of rapidly expanding supercritical solutions: A first approach: We consider the case when a supercritical fluid emerges at sonic speed from a\nsmall orifice in a high pressure chamber. The subsequent expansion causes a\npressure drop and the fluid then enters a regime where its equation of state in\n$P-V$ space becomes concave towards the origin. This is the signal for an\nexpansion shock to occur in a non-ideal fluid. This paper provides the details\nof an analytic calculation of the shape and location of this expansion shock\nusing Whitham's front-tracking method. Dependence of the shape of the front on\nvarious operating conditions was calculated for the particular case of\nsupercritical carbon dioxide. The results shed light on the rapid expansion of\nsupercritical solutions (RESS), a process which is used in many manufacturing\ntechnologies.",
        "positive": "Asymmetry in Polymer-Solvent Interactions Yields Complex\n  Thermoresponsive Behavior: Thermoresponsive polymers hold both fundamental and technological importance,\nbut the essential physics driving their intriguing behavior is not wholly\nunderstood. We introduce a lattice framework that incorporates elements of\nFlory-Huggins solution theory and the $q$-state Potts model to study the phase\nbehavior of polymer solutions and single-chain conformational characteristics.\nImportantly, the framework does not employ any temperature- or\ncomposition-dependent parameters. With this minimal Flory-Huggins-Potts\nframework, we show that orientation-dependent interactions, specifically\nbetween monomer segments and solvent particles, are alone sufficient to observe\nupper critical solution temperatures, miscibility loops, and hourglass-shaped\nspinodal curves. Signatures of emergent phase behavior are found in\nsingle-chain Monte Carlo simulations, which display heating- and\ncooling-induced coil-globule transitions linked to energy fluctuations. The\nmodel also capably describes a range of experimental systems. This work\nprovides new insights regarding the microscopic physics that underpin complex\nthermoresponsive behavior in polymers."
    },
    {
        "anchor": "Wetting hysteresis induces effective unidirectional water transport\n  through a fluctuating nanochannel: We propose a water pump that actively transports water molecules through\nnanochannels. Spatially asymmetric thermal fluctuations imposed on the channel\nradius cause unidirectional water flow without osmotic pressure, which can be\nattributed to hysteresis in the cyclic transition between the wetting/drying\nstates. We show that the water transport depends on fluctuations, such as\nwhite, Brownian, and pink noises. Because of the high-frequency components in\nwhite noise, fast switching of open and close states inhibits channel wetting.\nConversely, pink and Brownian noises generate high-pass filtered net flow.\nBrownian fluctuation leads to a faster water transport rate, whereas pink noise\nhas a higher capability to overcome osmotic pressure in the opposite direction.\nA trade-off relationship exists between the resonant frequency of the\nfluctuation and the flow amplification. The proposed pump can be considered as\nan analogy for the reversed Carnot cycle, which is the upper limit on the\nenergy conversion efficiency.",
        "positive": "Geometry-Induced Dynamics of Confined Chiral Active Matter: Controlling the motion of active matter is a central issue that has recently\ngarnered significant attention in fields ranging from non-equilibrium physics\nto chemical engineering and biology. Distinct methods for controlling active\nmatter have been developed, and physical confinement to limited space and\nactive matter with broken rotational symmetry (chirality) are two prominent\nmechanisms. However, the interplay between pattern formation due to physical\nconstraints and the ordering by chiral motion needs to be better understood. In\nthis study, we conduct numerical simulations of chiral self-propelled particles\nunder circular boundary confinement. The collective motion of confined\nself-propelled particles can take drastically different forms depending on\ntheir chirality. The balance of orientation changes between particle\ninteraction and the boundary wall is essential for generating ordered\ncollective motion. Our results clarify the role of the steric boundary effect\nin controlling chiral active matter."
    },
    {
        "anchor": "The segregation instability of a sheared suspension film: Starting from the equations of Stokes flow and the mass conservation of\nparticles as determined by shear-induced diffusion, we derive the coupled\nequations for the dynamics of particle concentration and film thickness for the\nfree-surface flow of a fluid film pulled up by a tilted wall rising from a pool\nof neutrally buoyant, non-Brownian suspension. We find an instability of the\nfilm with respect to axial undulations of film thickness and modulations of\nparticle concentration, and the instability growth-rate increases as a certain\ncombination of the two dimensionless shear induced diffusivities (which\ndetermine the particle flux driven by concentration and shear rate gradients)\nfalls below a critical value. This reinforces the conclusions of {\\it Phys.\nFluids} {\\bf 13} (12), p. 3517 (2001), suggesting an explanation of the\nexperiments of Tirumkudulu {\\it et al.}, Phys. Fluids {\\bf 11}, 507-509 (1999);\n{\\it ibid.} {\\bf 12}, 1615 (2000). In addition, we predict a ``pile-up''\ninstability in which perturbations that vary in the direction of the wall\nvelocity are amplified; this instability is not driven by shear-induced\nmigration, but is a result of the dependence of the suspension viscosity on the\nparticle concentration.",
        "positive": "Instabilities, motion and deformation of active fluid droplets: We consider two minimal models of active fluid droplets that exhibit complex\ndynamics including steady motion, deformation, rotation and oscillating motion.\nFirst we consider a droplet with a concentration of active contractile matter\nadsorbed to its boundary. We analytically predict activity driven instabilities\nin the concentration profile, and compare them to the dynamics we find from\nsimulations. Secondly, we consider a droplet of active polar fluid of constant\nconcentration. In this system we predict, motion and deformation of the\ndroplets in certain activity ranges due to instabilities in the polarisation\nfield. Both these systems show spontaneous transitions to motility and\ndeformation which resemble dynamics of the cell cytoskeleton in animal cells."
    },
    {
        "anchor": "Bayesian algorithms for recovering structure from single-particle\n  diffraction snapshots of unknown orientation: a comparison: The advent of X-ray Free Electron Lasers promises the possibility to\ndetermine the structure of individual particles such as microcrystallites,\nviruses and biomolecules from single-shot diffraction snapshots obtained before\nthe particle is destroyed by the intense femtosecond pulse. This program\nrequires the ability to determine the orientation of the particle giving rise\nto each snapshot at signal levels as low as ~10-2 photons/pixel. Two apparently\ndifferent approaches have recently demonstrated this capability. Here we show\nthey represent different implementations of the same fundamental approach, and\nidentify the primary factors limiting their performance.",
        "positive": "Polarizable polymer chain under external electric field in a dilute\n  polymer solution: We study the conformational behavior of polarizable polymer chain under an\nexternal homogeneous electric field within the Flory type self-consistent field\ntheory. We consider the influence of electric field on the polymer coil as well\nas on the polymer globule. We show that when the polymer chain conformation is\na coil, application of external electric field leads to its additional\nswelling. However, when the polymer conformation is a globule, a sufficiently\nstrong field can induce a globule-coil transition. We show that such\n$\"$field-induced$\"$ globule-coil transition at the sufficiently small monomer\npolarizabilities goes quite smoothly. On the contrary, when the monomer\npolarizability exceeds a certain threshold value, the globule-coil transition\noccurs as a dramatic expansion in the regime of first-order phase transition.\nThe developed theoretical model can be applied to predicting polymer globule\ndensity change under external electric field in order to provide more efficient\nprocesses of polymer functionalization, such as sorption, dyeing, chemical\nmodification, etc."
    },
    {
        "anchor": "Origin of Non-cubic Scaling Law in Disordered Granular Packing: Recent diffraction experiments on metallic glasses have unveiled an\nunexpected non-cubic scaling law between density and average interatomic\ndistance, which lead to the speculations on the presence of fractal glass\norder. Using X-ray tomography we identify here a similar non-cubic scaling law\nin disordered granular packing of spherical particles. We find that the scaling\nlaw is directly related to the contact neighbors within first nearest neighbor\nshell, and therefore is closely connected to the phenomenon of jamming. The\nseemingly universal scaling exponent around 2.5 arises due to the isostatic\ncondition with contact number around 6, and we argue that the exponent should\nnot be universal.",
        "positive": "Switch-like surface binding of competing multivalent particles: Multivalent particles competing for binding on the same surface can exhibit\nswitch-like behaviour, depending on the concentration of receptors on the\nsurface. When the receptor concentration is low, energy dominates the free\nenergy of binding, and particles having a small number of strongly-binding\nligands preferentially bind to the surface. At higher receptor concentrations,\nmultivalent effects become significant, and entropy dominates the binding free\nenergy; particles having many weakly-binding ligands preferentially bind to the\nsurface. Between these two regimes there is a \"switch-point\", at which the\nsurface binds the two species of particles equally strongly. We demonstrate\nthat a simple theory can account for this switch-like behaviour and present\nnumerical calculations that support the theoretical predictions. We argue that\nbinding selectivity based on receptor density, rather than identity, may have\npractical applications."
    },
    {
        "anchor": "A Simulation Method to Resolve Hydrodynamic Interactions in Colloidal\n  Dispersions: A new computational method is presented to resolve hydrodynamic interactions\nacting on solid particles immersed in incompressible host fluids. In this\nmethod, boundaries between solid particles and host fluids are replaced with a\ncontinuous interface by assuming a smoothed profile. This enabled us to\ncalculate hydrodynamic interactions both efficiently and accurately, without\nneglecting many-body interactions. The validity of the method was tested by\ncalculating the drag force acting on a single cylindrical rod moving in an\nincompressible Newtonian fluid. This method was then applied in order to\nsimulate sedimentation process of colloidal dispersions.",
        "positive": "The statistics of particle velocities in dense granular flows: We present measurements of the particle velocity distribution in the flow of\ngranular material through vertical channels. Our study is confined to dense,\nslow flows where the material shears like a fluid only in thin layers adjacent\nto the walls, while a large core moves without continuous deformation, like a\nsolid. We find the velocity distribution to be non-Gaussian, anisotropic, and\nto follow a power law at large velocities. Remarkably, the distribution is\nidentical in the fluid-like and solid-like regions. The velocity variance is\nmaximum at the core, defying predictions of hydrodynamic theories. We show\nevidence of spatially correlated motion, and propose a mechanism for the\ngeneration of fluctuational motion in the absence of shear."
    },
    {
        "anchor": "Charged surface in salty water with multivalent ions: Giant inversion of\n  charge: Screening of a strongly charged macroion by oppositely charged colloidal\nparticles, micelles, or short polyelectrolytes is considered. Due to strong\nlateral repulsion such multivalent counterions form a strongly correlated\nliquid at the surface of the macroion. This liquid provides correlation induced\nattraction of multivalent counterions to the macroion surface. As a result even\na moderate concentration of multivalent counterions in the solution inverts the\nsign of the net macroion charge. We show that at high concentration of\nmonovalent salt the absolute value of inverted charge can be larger than the\nbare one. This giant inversion of charge can be observed in electrophoresis.",
        "positive": "Coarse-graining polymers as soft colloids: We show how to coarse grain polymers in a good solvent as single particles,\ninteracting with density-independent or density-dependent interactions. These\ninteractions can be between the centres of mass, the mid-points or end-points\nof the polymers. We also show how to extend these methods to polymers in poor\nsolvents and mixtures of polymers. Treating polymers as soft colloids can\ngreatly speed up the simulation of complex many-polymer systems, including\npolymer-colloid mixtures."
    },
    {
        "anchor": "Crystal phases of soft spheres systems in a slab geometry: We have identified the ground state configurations of soft particles\n(interacting via inverse power potentials) confined between two hard,\nimpenetrable walls. To this end we have used a highly reliable optimization\nscheme at {\\it vanishing} temperature while varying the wall separation over a\nrepresentative range. Apart from the expected layered triangular and square\nstructures (which are compatible with the three dimensional bulk fcc lattice),\nwe have identified a cascade of highly complex intermediate structures. Taking\nbenefit of the general scaling properties of inverse power potentials, we could\nidentify -- for a given softness value -- one single master curve which relates\nthe energy to the wall separation, irrespective of the density of the system.\nVia extensive Monte Carlo simulations, we have performed closer investigations\nof these intermediate structures at {\\it finite} temperature: we could provide\nevidence to which extent these particle arrangements remain stable over a\nrelatively large temperature range.",
        "positive": "Equilibrium Phase Behavior of a Continuous-Space Microphase Former: Periodic microphases universally emerge in systems for which short-range\ninter-particle attraction is frustrated by long-range repulsion. The\nmorphological richness of these phases makes them desirable material targets,\nbut our relatively coarse understanding of even simple models limits our grasp\nof their assembly. We report here the solution of the equilibrium phase\nbehavior of a microscopic microphase former through specialized Monte Carlo\nsimulations. The results for the ordered regime qualitatively agree with a\nLandau-type free energy description and highlight the nontrivial dynamical\ninterplay between micelle, gel and microphase formation."
    },
    {
        "anchor": "Dynamic light scattering study on phase separation of a protein-water\n  mixture: Application on cold cataract development in the ocular lens: We present a detailed dynamic light scattering study on the phase separation\nin the ocular lens emerging during cold cataract development. Cold cataract is\na phase separation effect that proceeds via spinodal decomposition of the lens\ncytoplasm with cooling. Intensity auto-correlation functions of the lens\nprotein content are analyzed with the aid of two methods providing information\non the populations and dynamics of the scattering elements associated with cold\ncataract. It is found that the temperature dependence of many measurable\nparameters changes appreciably at the characteristic temperature ~16+1 oC which\nis associated with the onset of cold cataract. Extending the temperature range\nof this work to previously inaccessible regimes, i.e. well below the phase\nseparation or coexistence curve at Tcc, we have been able to accurately\ndetermine the temperature dependence of the collective and self-diffusion\ncoefficient of proteins near the spinodal. The analysis showed that the\ndynamics of proteins bears some resemblance to the dynamics of structural\nglasses where the apparent activation energy for particle diffusion increases\nbelow Tcc indicating a highly cooperative motion. Application of ideas\ndeveloped for studying the critical dynamics of binary protein/solvent\nmixtures, as well as the use of a modified Arrhenius equation, enabled us to\nestimate the spinodal temperature Tsp of the lens nucleus. The applicability of\ndynamic light scattering as a non-invasive, early-diagnostic tool for ocular\ndiseases is also demonstrated in the light of the findings of the present\npaper.",
        "positive": "Spontaneous particle desorption and \"Gorgon\" drop formation from\n  particle-armored oil drops upon cooling: Drop \"self-shaping\" is a phenomenon in which cooled oily emulsion drops\nundergo a spectacular series of shape transformations (Denkov et al., Nature\n528, 2015, 392). Solid particles adsorbed on the oil-water interface could\naffect this drop self-shaping process in multiple ways which have not been\nstudied. We prepared Pickering emulsions stabilized by spherical latex\nparticles and afterwards added surfactant of low concentration which enabled\ndrop self-shaping. Next we observed by optical microscopy the processes which\noccur upon emulsion cooling. Several new processes were observed: (1) Adsorbed\nlatex particles rearranged into regular hexagonal lattices upon freezing of the\nsurfactant adsorption layer. (2) Spontaneous particle desorption from the drop\nsurface was observed at a certain temperature - this phenomenon is rather\nremarkable, as the solid particles are known to irreversibly adsorb on fluid\ninterfaces. (3) Very strongly adhered particles to drop surfaces acted as a\ntemplate to enable the formation of tens to hundreds of semi-liquid fibers,\ngrowing outwards from the drop surface, thus creating a shape resembling the\nGorgon head from Greek mythology. We provide mechanistic explanations of all\nobserved phenomena using our understanding of the rotator phase formation on\nthe surface of cooled drops."
    },
    {
        "anchor": "Design rules for the self-assembly of a protein crystal: Theories of protein crystallization based on spheres that form close-packed\ncrystals predict optimal assembly within a `slot' of second virial coefficients\nand enhanced assembly near the metastable liquid-vapor critical point. However,\nmost protein crystals are open structures stabilized by anisotropic\ninteractions. Here, we use theory and simulation to show that assembly of one\nsuch structure is not predicted by the second virial coefficient or enhanced by\nthe critical point. Instead, good assembly requires that the thermodynamic\ndriving force be on the order of the thermal energy and that interactions be\nmade as nonspecific as possible without promoting liquid-vapor phase\nseparation.",
        "positive": "Flow velocity-dependent transition of anisotropic crack patterns in\n  CaCO$_3$ pastes: We investigate the desiccation crack patterns on the surface of a drying\npaste made of calcium carbonate (CaCO$_3$) powder and distilled water. Forced\nvibration of the CaCO$_3$ paste prior to drying results in an anisotropic crack\npattern, in which many long cracks develop along a specific preferred\ndirection. We reveal that the preferred direction changes from perpendicular to\nparallel to the vibration direction at the threshold velocity of vibration. The\ntransition is attributed to the reorientation of constituent particles\nsubjected to the forced oscillatory flow of fluid in the paste."
    },
    {
        "anchor": "Nonlinear dielectric response at the excess wing of glass-forming\n  liquids: We present nonlinear dielectric measurements of glass-forming glycerol and\npropylene carbonate applying electrical fields up to 671 kV/cm. The\nmeasurements extend to sufficiently high frequencies to allow for the\ninvestigation of the nonlinear behavior in the regime of the so-far mysterious\nexcess wing, showing up in the loss spectra of many glass formers as a second\npower law at high frequencies. Surprisingly, we find a complete lack of\nnonlinear behavior in the excess wing, in marked contrast to the\nalpha-relaxation where, in agreement with previous reports, a strong increase\nof dielectric constant and loss is found.",
        "positive": "Interplay between Brownian and hydrodynamic tracer diffusion in\n  suspensions of swimming microorganisms: The general problem of tracer diffusion in non-equilibrium baths is important\nin a wide range of systems, from the cellular level to geographical\nlengthscales. In this paper, we revisit the archetypical example of such a\nsystem: a collection of small passive particles immersed in a dilute suspension\nof non-interacting dipolar microswimmers, representing bacteria or algae. In\nparticular, we consider the interplay between thermal (Brownian) diffusion and\nhydrodynamic (active) diffusion due to the persistent advection of tracers by\nmicroswimmer flow fields. Previously, it has been argued that even a moderate\namount of Brownian diffusion is sufficient to significantly reduce the\npersistence time of tracer advection, leading to a significantly reduced value\nof the effective active diffusion coefficient $D_A$ compared to the\nnon-Brownian case. Here, we show by large-scale simulations and kinetic theory\nthat this effect is in fact only practically relevant for microswimmers that\neffectively remain stationary while still stirring up the surrounding fluid,\nso-called \\emph{shakers}. In contrast, for moderate and high values of the\nswimming speed $v_s$, relevant for biological microswimmer suspensions, the\neffect of Brownian motion on $D_A$ is negligible, leading to the effects of\nadvection by microswimmers and Brownian motion being additive. This conclusion\ncontrasts with previous results from the literature, and encourages a\nreinterpretation of recent experimental measurements of $D_A$ for tracer\nparticles of varying size in bacterial suspensions."
    },
    {
        "anchor": "Nematic colloidal micro-robots as physically intelligent systems: Physically intelligent micro-robotic systems exploit information embedded in\nmicro-robots, their colloidal cargo, and their milieu to interact, assemble and\nform functional structures. Nonlinear anisotropic fluids like nematic liquid\ncrystals (NLCs) provide untapped opportunities to embed interactions via their\ntopological defects, complex elastic responses, and their ability to\ndramatically restructure in dynamic settings. Here we design and fabricate a\n4-armed ferromagnetic micro-robot to embed and dynamically reconfigure\ninformation in the nematic director field, generating a suite of physical\ninteractions for cargo manipulation. The micro-robot shape and surface\nchemistry are designed to generate a nemato-elastic energy landscape in the\ndomain that defines multiple modes of emergent, bottom-up interactions with\npassive colloids. Micro-robot rotation expands the ability to sculpt\ninteractions; the energy landscape around a rotating micro-robot is dynamically\nreconfigured by complex far-from-equilibrium dynamics of the micro-robot's\ncompanion topological defect. These defect dynamics allow transient information\nto be programmed into the domain and exploited for top-down cargo manipulation.\nWe demonstrate robust micro-robotic manipulation strategies that exploit these\ndiverse modes of nemato-elastic interaction to achieve cargo docking,\ntransport, release, and assembly of complex reconfigurable structures at\nmulti-stable sites. Such structures are of great interest to future\ndevelopments of LC-based advanced optical device and micro-manufacturing in\nanisotropic environments.",
        "positive": "Universal Particle Kinetic Distribution in Crowded Environments: We study many-particle transport in heterogeneous, crowded environments at\ndifferent particle P\\'{e}clet numbers ($Pe^*$). We demonstrate that a modified\nNakagami-$m$ function describes particle velocity probability distributions\nwhen particle deposition occurs. We assess the universality of said function\nthrough comparison against new Lagrangian simulations of various particle types\nas well as experimental data from the literature. We construe the function's\nphysical meaning as its ability to explain particle deposition in terms of\n$Pe^*$ and the competition between distributions of energy barriers for\nparticle release and particles' diffusive energy."
    },
    {
        "anchor": "Energy Loss at Propagating Jamming Fronts in Granular Gas Clusters: We explore the initial moments of impact between two dense granular clusters\nin a two-dimensional geometry. The particles are composed of solid CO$_{2}$ and\nare levitated on a hot surface. Upon collision, the propagation of a dynamic\n\"jamming front\" produces a distinct regime for energy dissipation in a granular\ngas in which the translational kinetic energy decreases by over 90%.\nExperiments and associated simulations show that the initial loss of kinetic\nenergy obeys a power law in time, $\\Delta E=-Kt^{3/2}$, a form that can be\npredicted from kinetic arguments.",
        "positive": "Tetrahedral colloidal clusters from random parking of bidisperse spheres: Using experiments and simulations, we investigate the clusters that form when\ncolloidal spheres stick irreversibly to -- or \"park\" on -- smaller spheres. We\nuse either oppositely charged particles or particles labeled with complementary\nDNA sequences, and we vary the ratio $\\alpha$ of large to small sphere radii.\nOnce bound, the large spheres cannot rearrange, and thus the clusters do not\nform dense or symmetric packings. Nevertheless, this stochastic aggregation\nprocess yields a remarkably narrow distribution of clusters with nearly 90%\ntetrahedra at $\\alpha=2.45$. The high yield of tetrahedra, which reaches 100%\nin simulations at $\\alpha=2.41$, arises not simply because of packing\nconstraints, but also because of the existence of a long-time lower bound that\nwe call the \"minimum parking\" number. We derive this lower bound from solutions\nto the classic mathematical problem of spherical covering, and we show that\nthere is a critical size ratio $\\alpha_c=(1+\\sqrt{2})\\approx 2.41$, close to\nthe observed point of maximum yield, where the lower bound equals the upper\nbound set by packing constraints. The emergence of a critical value in a random\naggregation process offers a robust method to assemble uniform clusters for a\nvariety of applications, including metamaterials."
    },
    {
        "anchor": "Acoustoelastic analysis of soft viscoelastic solids with application to\n  pre-stressed phononic crystals: The effective dynamic properties of specific periodic structures involving\nrubber-like materials can be adjusted by pre-strain, thus facilitating the\ndesign of custom acoustic filters. While nonlinear viscoelastic behaviour is\none of the main features of soft solids, it has been rarely incorporated in the\nstudy of such phononic media. Here, we study the dynamic response of nonlinear\nviscoelastic solids within a 'small-on-large' acoustoelasticity framework, that\nis we consider the propagation of small amplitude waves superimposed on a large\nstatic deformation. Incompressible soft solids whose behaviour is described by\nthe Fung-Simo quasi-linear viscoelasticy theory (QLV) are considered. We derive\nthe incremental equations using stress-like memory variables governed by linear\nevolution equations. Thus, we show that wave dispersion follows a\nstrain-dependent generalised Maxwell rheology. Illustrations cover the\npropagation of plane waves under homogeneous tensile strain in a QLV\nMooney-Rivlin solid. The acoustoelasticity theory is then applied to phononic\ncrystals involving a lattice of hollow cylinders, by making use of a dedicated\nperturbation approach. In particular, results highlight the influence of\nviscoelastic dissipation on the location of the first band gap. We show that\ndissipation shifts the band gap frequencies, simultaneously increasing the band\ngap width. These results are relevant to practical applications of soft\nviscoelastic solids subject to static pre-stress.",
        "positive": "Active acoustic switches using 2D granular crystals: We employ numerical simulations to study active transistor-like switches made\nfrom two-dimensional (2D) granular crystals containing two types of grains with\nthe same size, but different masses. We tune the mass contrast and arrangement\nof the grains to maximize the width of the frequency band gap in the device.\nThe input signal is applied to a single grain on one side of the device, and\nthe output signal is measured from another grain on the other side of the\ndevice. Changing the size of one or many grains tunes the pressure, which\ncontrols the vibrational response of the device. Switching between the on and\noff states is achieved using two mechanisms: 1) pressure-induced switching\nwhere the interparticle contact network is the same in the on and off states,\nand 2) switching through contact breaking. In general, the performance of the\nacoustic switch, as captured by the gain ratio and switching time between the\non and off states, is better for pressure-induced switching. We show that in\nthese acoustic switches the gain ratio between the on and off states can be\nlarger than $10^4$ and the switching time (multiplied by the driving frequency)\nis comparable to that obtained recently for sonic crystals and less than that\nfor photonic transistor-like switches. Since the self-assembly of grains with\ndifferent masses into 2D granular crystals is challenging, we describe\nsimulations of circular grains with small circular knobs placed symmetrically\naround the perimeter mixed with circular grains without knobs. Using umbrella\nsampling techniques, we show that devices with grains with $3$ knobs most\nefficiently form the hexagonal crystals that yield the largest band gap."
    },
    {
        "anchor": "Ring-like spin segregation of binary mixtures in a high-velocity\n  rotating drum: We present molecular dynamics simulations on the segregation of binary\nmixtures in a high-velocity rotating drum. Depending on the ratio of particle's\nradius and density, the ring-like spin segregation patterns in radial direction\nshow similarities to the Brazil-nut effect and its reverse form. The smaller\nand heavier particles are easier to accumulate towards the drum wall and the\nbigger and lighter ones towards the drum center. Furthermore, we quantify the\neffects of particle's radius and density on the segregation states and plot the\nphase diagram of segregation in the ${\\rho_b}/{\\rho_s}$ - ${r_b}/{r_s}$ space.\nThe observed phenomena can also be well explained by the combined actions,\ni.e., the percolation effect and the buoyancy effect.",
        "positive": "W-potentials in nonlinear biophysics of microtubules: In the present article we investigate the nonlinear dynamics of microtubules,\nthe basic components of the eukaryotic cytoskeleton, and rely on the known\ngeneral model. A crucial interaction among constitutive particles is modelled\nusing W-potential. Three kinds of this potential are studied, symmetrical and\ntwo non-symmetrical. We demonstrate an advantage of the latter ones."
    },
    {
        "anchor": "Fracture of a biopolymer gel as a viscoplastic disentanglement process: We present an extensive experimental study of mode-I, steady, slow crack\ndynamics in gelatin gels. Taking advantage of the sensitivity of the elastic\nstiffness to gel composition and history we confirm and extend the model for\nfracture of physical hydrogels which we proposed in a previous paper (Nature\nMaterials, doi:10.1038/nmat1666 (2006)), which attributes decohesion to the\nviscoplastic pull-out of the network-constituting chains. So, we propose that,\nin contrast with chemically cross-linked ones, reversible gels fracture without\nchain scission.",
        "positive": "Optoelectronic switching of addressable molecular crossbar junctions: This letter reports on the observation of optoelectronic switching in\naddressable molecular crossbar junctions fabricated using polymer\nstamp-printing method. The active medium in the junction is a molecular\nself-assembled monolayer softly sandwiched between gold electrodes. The\nmolecular junctions are investigated through currentvoltage measurements at\nvaried temperature (from 95 to 300 K) in high vacuum condition. The junctions\nshow reversible optoelectronic switching with the highest on/off ratio of 3\norders of magnitude at 95 K. The switching behavior is independent of both\noptical wavelength and molecular structure, while it strongly depends on the\ntemperature. Initial analysis indicates that the distinct binding nature of the\nmolecule/electrode interfaces play a dominant role in the switching\nperformance."
    },
    {
        "anchor": "Patterns driven by combined AC and DC electric fields in nematic liquid\n  crystals: The effect of superimposed ac and dc electric fields on the formation of\nelectroconvection and flexoelectric patterns in nematic liquid crystals was\nstudied. For selected ac frequencies an extended standard model of the\nelectro-hydrodynamic instabilities was used to characterize the onset of\npattern formation in the two-dimensional parameter space of the magnitudes of\nthe ac and dc electric field components. Numerical as well as approximate\nanalytical calculations demonstrate that depending on the type of patterns and\non the ac frequency, the combined action of ac and dc fields may either enhance\nor suppress the formation of patterns. The theoretical predictions are\nqualitatively confirmed by experiments in most cases. Some discrepancies,\nhowever, seem to indicate the need to extend the theoretical description.",
        "positive": "Melting of a two-dimensional monodisperse cluster crystal to a cluster\n  liquid: Monodisperse ensembles of particles that have cluster crystalline phases at\nlow temperatures can model a number of physical systems, such as vortices in\ntype-1.5 superconductors, colloidal suspensions and cold atoms. In this work we\nstudy a two-dimensional cluster-forming particle system interacting via an\nultrasoft potential. We present a simple mean-field characterization of the\ncluster-crystal ground state, corroborating with Monte Carlo simulations for a\nwide range of densities. The efficiency of several Monte Carlo algorithms are\ncompared and the challenges of thermal equilibrium sampling are identified. We\ndemonstrate that the liquid to cluster-crystal phase transition is of first\norder and occurs in a single step, and the liquid phase is a cluster liquid."
    },
    {
        "anchor": "Fatigue failure of amorphous alloys under cyclic shear deformation: The accumulation of plastic deformation and flow localization in amorphous\nalloys under periodic shear are investigated using molecular dynamics\nsimulations. We study a well-annealed binary mixture of one million atoms\nsubjected to oscillatory shear deformation with strain amplitudes slightly\nabove a critical value. We find that upon approaching a critical strain\namplitude from above, the number of shear cycles until the yielding transition\nis well described by a power-law function. Remarkably, the potential energy at\nthe end of each cycle as a function of the normalized number of cycles is\nnearly independent of the strain amplitude, which allows for estimation of the\nfatigue lifetime at a given strain amplitude. The analysis on nonaffine\ndisplacements of atoms elucidates the process of strain localization, including\nirreversible rearrangements of small clusters until the formation of a\nsystem-spanning shear band.",
        "positive": "Non-linear double-peeling: experimental vs. theoretical predictions: The double peeling of detachment of non-linear adhesive tapes from a flat\nPoly(methylmethacrylate) (PMMA) surface has been investigated from both\nexperimental and theoretical point of view. Double peeling tests show that, as\nthe detachment process advances, the peeling angle stabilizes on a limiting\nvalue {\\theta}lim corresponding to a critical pull-off force Fc above which the\ntape is completely detached from the substrate. This observed behavior is in\ngood agreement with results obtained following the new theory of multiple\npeeling and taking into account the hardening-softening non-linear behavior of\nthe experimentally tested adhesive tapes and clarifies some aspects of the\nexperimental data. In particular, the theoretical model shows that the value of\nthe limiting peeling angle depends on the geometry of the adhesive tape as well\nas on the stiffness properties and on the interfacial energy {\\Delta}{\\gamma}.\nFinally, theoretical predictions confirm that solutions with a peeling angle\nlower than {\\theta}lim are unstable."
    },
    {
        "anchor": "The ideal glass transition of Hard Spheres: We use the replica method to study the ideal glass transition of a liquid of\nidentical Hard Spheres. We obtain estimates of the configurational entropy in\nthe liquid phase, of the Kauzmann packing fraction, in the range 0.58--0.62,\nand of the random close packing density, in the range 0.64--0.67, depending on\nthe approximation we use for the equation of state of the liquid. We also\ncompute the pair correlation function in the glassy states (i.e., dense\namorphous packings) and we find that the mean coordination number at random\nclose packing is equal to 6. All these results compare well with numerical\nsimulations and with other existing theories.",
        "positive": "Density functional theory of electrowetting: The phenomenon of electrowetting, i.e., the dependence of the macroscopic\ncontact angle of a fluid on the electrostatic potential of the substrate, is\nanalyzed in terms of the density functional theory of wetting. It is shown that\nelectrowetting is not an electrocapillarity effect, i.e., it cannot be\nconsistently understood in terms of the variation of the substrate-fluid\ninterfacial tension with the electrostatic substrate potential, but it is\nrelated to the depth of the effective interface potential. The key feature,\nwhich has been overlooked so far and which occurs naturally in the density\nfunctional approach is the structural change of a fluid if it is brought into\ncontact with another fluid. These structural changes occur in the present\ncontext as the formation of finite films of one fluid phase in between the\nsubstrate and the bulk of the other fluid phase. The non-vanishing Donnan\npotentials (Galvani potential differences) across such film-bulk fluid\ninterfaces, which generically occur due to an unequal partitioning of ions as a\nresult of differences of solubility contrasts, lead to correction terms in the\nelectrowetting equation, which become relevant for sufficiently small substrate\npotentials. Whereas the present density functional approach confirms the\ncommonly used electrocapillarity-based electrowetting equation as a good\napproximation for the cases of metallic electrodes or electrodes coated with a\nhydrophobic dielectric in contact with an electrolyte solution and an ion-free\noil, a significantly reduced tendency for electrowetting is predicted for\nelectrodes coated with a dielectric which is hydrophilic or which is in contact\nwith two immiscible electrolyte solutions."
    },
    {
        "anchor": "Self-Propelled Colloidal Particle Near a Planar Wall: A Brownian\n  Dynamics Study: Miniaturized, self-propelled locomotors use chemo-mechanical transduction\nmechanisms to convert fuel in the environment to autonomous motion. Recent\nexperimental and theoretical studies demonstrate that these autonomous engines\ncan passively follow the contours of solid boundaries they encounter. Boundary\nguidance, however, is not necessarily stable: Mechanical disturbances can cause\nthe motor to hydrodynamically depart from the passively guided pathway.\nFurthermore, given the scaled-down size of micromotors (typically 100 nm -10\n$\\mu$m), Brownian thermal fluctuation forces are necessarily important and\nthese stochastic forces can randomize passively-steered trajectories.\n  Here we examine theoretically the stability of boundary guided motion of\nmicromotors along infinite planar walls to mechanical disturbances and to\nBrownian forces. Our aim is to understand under what conditions this passively\nguided motion is stable. We choose a locomotor design in which spherical\ncolloids are partially coated with a catalytic cap that reacts with solute to\nproduce a product. The product is repelled from the particle surface, causing\nthe particle to move with the inert face at the front (autonomous motion via\nself-diffusiophoresis). When propelled towards a planar wall, deterministic\nhydrodynamic studies demonstrate that these locomotors can exhibit, for large\nenough cap sizes, steady trajectories in which the particle either skims\nunidirectionally along the surface at a constant distance from the wall, or\nbecomes stationary. We first investigate the linear hydrodynamic stability of\nthese states by expanding the equations of motion about the states, and find\nthat linear perturbations decay exponentially in time. We then study the\neffects of thermal fluctuations by formulating a Langevin equation for the\nparticle motion which includes the Brownian stochastic force...",
        "positive": "Dark states of dressed Bose-Einstein condensates: We combine the ideas of dressed Bose-Einstein condensates, where an\nintracavity optical field allows one to design coupled, multicomponent\ncondensates, and of dark states of quantum systems, to generate a full quantum\nentanglement between two matter waves and two optical waves. While the matter\nwaves are macroscopically populated, the two optical modes share a single\nphoton. As such, this system offers a way to influence the behaviour of a\nmacroscopic quantum system via a microscopic ``knob''."
    },
    {
        "anchor": "Re-entrant spin glass and magnetoresistance in\n  Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide: We have investigated the static and dynamic response of magnetic clusters in\nCo_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide, where a sequence of magnetic\nphase transitions, i.e., paramagnetic (PM) to ferromagnetic at T_{C} $\\leq$\n270K and ferromagnetic to canted spin glass state at T_f$ $\\leq$ 125K is\nobserved.",
        "positive": "Segregation of large particles in dense granular flows: A granular\n  Saffman effect?: We report on the scaling between the lift force and the velocity lag\nexperienced by a single particle of different size in a monodisperse dense\ngranular chute flow. The similarity of this scaling to the Saffman lift force\nin (micro) fluids, suggests an inertial origin for the lift force responsible\nfor segregation of (isolated, large) intruders in dense granular flows. We also\nobserve an anisotropic pressure/stress field surrounding the particle, which\npotentially lies at the origin of the velocity lag. These findings are relevant\nfor modelling and theoretical predictions of particle-size segregation. At the\nsame time, the suggested interplay between polydispersity and inertial effects\nin dense granular flows with stress- and strain-gradients, implies striking new\nparallels between fluids, suspensions and granular flows with wide application\nperspectives."
    },
    {
        "anchor": "Variable-cell method for stress-controlled jamming of athermal,\n  frictionless grains: A new method is introduced to simulate jamming of polyhedral grains under\ncontrolled stress that incorporates global degrees of freedom through the\nmetric tensor of a periodic cell containing grains. Jamming under\nhydrostatic/isotropic stress and athermal conditions leads to a precise\ndefinition of the ideal jamming point at zero shear stress. The structures of\ntetrahedra jammed hydrostatically exhibit less translational order and lower\njamming-point density than previously described `maximally random jammed' hard\ntetrahedra. Under the same conditions, cubes jam with negligible nematic order.\nGrains with octahedral symmetry jam in the large-system limit with an abundance\nof face-face contacts in the absence of nematic order. For sufficiently large\nface-face contact number, percolating clusters form that span the entire\nsimulation box. The response of hydrostatically jammed tetrahedra and cubes to\nshear-stress perturbation is also demonstrated with the variable-cell method.",
        "positive": "Single particle slow dynamics of confined water: Molecular dynamics simulations of SPC/E water confined in a Silica pore are\npresented. The simulations have been performed at different hydration levels\nand temperatures to study the single-particle dynamics. Due to the confinement\nand to the presence of a hydrophilic surface, the dynamic behaviour of the\nliquid appears to be strongly dependent on the hydration level. On lowering\ntemperature and/or hydration level the intermediate scattering function\ndisplays a double-step relaxation behaviour whose long time tail is strongly\nnon-exponential. At higher hydrations two quite distinct subsets of water\nmolecules are detectable. Those belonging to the first two layers close to the\nsubstrate suffer a severe slowing down already at ambient temperature. While\nthe behaviour of the remaining ones is more resemblant to that of supercooled\nbulk SPC/E water. At lower hydrations and/or temperatures the onset of a slow\ndynamics due to the cage effect and a scenario typical of supercooled liquids\napproaching the kinetic glass transition is observed. Moreover, for low\nhydrations and/or temperatures, the intermediate scattering function clearly\ndisplays an overshoot, which can be assigned to the so called ``Boson Peak''."
    },
    {
        "anchor": "Critical Scaling of Bagnold Rheology at the Jamming Transition of\n  Frictionless Two Dimensional Disks: We carry out constant volume simulations of steady-state, shear driven,\nrheology in a simple model of bidisperse, soft-core, frictionless disks in two\ndimensions, using a dissipation law that gives rise to Bagnoldian rheology. We\ncarry out a detailed critical scaling analysis of our resulting data for\npressure $p$ and shear stress $\\sigma$, in order to determine the critical\nexponent $\\beta$ that describes the algebraic divergence of the Bagnold\ntransport coefficients, as the jamming transition is approached from below. We\nshow that it is necessary, for the strain rates considered in this work, to\nconsider the leading correction-to-scaling term in order to achieve a\nself-consistent analysis of our data. Our resulting value $\\beta\\approx 5.0\\pm\n0.4$ is clearly larger than the theoretical prediction by Otsuki and Hayakawa,\nand is consistent with earlier numerical results by Peyneau and Roux, and\nrecent theoretical predictions by DeGiuli et al. We have also considered the\nmacroscopic friction $\\mu\\equiv \\sigma/p$ and similarly find results consistent\nwith Peyneau and Roux, and with DeGiuli et al. Our results confirm that the\nshear driven jamming transition in Bagnoldian systems is well described by a\ncritical scaling theory (as was found previously for Newtonian systems), and we\nrelate this scaling theory to the phenomenological constituent laws for\ndilatancy and friction.",
        "positive": "Length-scales in sheared soft matter depend sensitively on molecular\n  interactions: The structure and degree of order in soft matter and other materials is\nintimately connected to the nature of the interactions between the particles.\nOne important research goal is to find suitable control mechanisms, to enhance\nor suppress different structures. Using dynamical density functional theory, we\ninvestigate the interplay between external shear and the characteristic\nlength-scales in the interparticle correlations of a model system. We show that\nshear can controllably change the characteristic length-scale from one to\nanother quite distinct value. Moreover, with specific small changes in the form\nof the particle interactions, the applied shear can either selectively enhance\nor suppress the different characteristic wavelengths of the system, thus\nshowing how to tune these. Our results suggest that the nonlinear response to\nflow can be harnessed to design novel actively responsive materials."
    },
    {
        "anchor": "S-shaped flow curves and local stress oscillations in confined shear\n  thickening suspensions: We experimentally investigated the role of boundary confinements in shear\nthickening suspensions. Unexpected rheological responses were observed across\nmultiple length scales under highly confined geometries. The flow curves were\nfound to equilibrate at very slow rates, and appeared S-shaped in steady\nstates. By combining shear rheological characterizations with boundary stress\nmicroscopy (BSM), we observed sustained local stress oscillations in confined\nsuspensions. The stress heterogeneities were induced by concentrated\nhigh-stress clusters that traveled stably along the flow direction. We show\nthat the growth and relaxation of these particle clusters contributed to the\nnon-monotonic flow curves, and mitigated the fluctuations of global shear rate.\nBy comparing the flow properties under different system sizes, we uncovered how\nboundary confinements effectively determined both the rheological and\nstatistical responses of dense suspensions to shear thickening transition.",
        "positive": "Velocity scaling in the region of orifice influence in silo draining\n  under gravity: This study utilizes computations based on soft-particle discrete element\nmethod for investigating the scaling of velocity in a two-dimensional silo\ndraining under gravity. We focus on the region situated directly above and in\nproximity to the outlet, referred to as the region of orifice influence (ROI).\nThe velocity at the exit scales with the outlet size, in agreement with\nprevious studies. The velocity in the ROI upstream of the outlet, however, does\nnot collapse to a single curve when scaled with the outlet size. We show that\nthe height of an $\\textit{equi-inertial}$ curve, which is defined to be a curve\non which the inertial number is constant, can be employed for scaling the\nvelocity in the ROI. The velocity corresponding to an equi-inertial curve, when\nmeasured relative to the outlet velocity, is considered for scaling. Results\nshow that the scaling holds very well for low inertial number corresponding to\nthe dense flow regime, whereas it breaks down for high inertial number region."
    },
    {
        "anchor": "Thermodynamic perturbation theory and equation of state developments: An alternative way of utilizing the thermodynamic perturbation theory of\nWertheim for the development of equations of state for associating fluid models\nis presented and detailed for water. The approach makes use of general features\nof the parameter of non-saturation to avoid the necessary solution of an\nalgebraic equation and unbinds the results from a tight dependence on details\nof the simple reference fluid model used in the perturbation theory.",
        "positive": "Failure of standard density functional theory to describe the phase\n  behavior of a fluid of hard right isosceles triangles: A fluid of hard right isosceles triangles was studied using an extension of\nScaled-Particle Density-Functional Theory which includes the exact third virial\ncoefficient. We show that the only orientationally ordered stable\nliquid-crystal phase predicted by the theory is the uniaxial nematic phase, in\nagreement with the second-order virial theory. By contrast, Monte Carlo\nsimulations predict exotic liquid-crystal phases exhibiting tetratic and\noctatic correlations, with orientational distribution functions having four and\neight equivalent peaks, respectively. This demonstrates the failure of the\nstandard Density Functional Theory based on two and three-body correlations to\ndescribe high-symmetry orientational phases in two-dimensional hard\nright-triangle fluids, and points to the necessity to reformulate the theory to\ntake into account high-order body correlations and ultimately particle\nself-assembling and clustering effects. This avenue may represent a great\nchallenge for future research, and we discuss some fundamental ideas to\nconstruct a modified version of Density-Functional Theory to account for these\nclustering effects."
    },
    {
        "anchor": "Simulation of catalytic reactions in open-cell foam structures: We describe a technique for particle-based simulations of heterogeneous\ncatalysis in open-cell foam structures, which is based on isotropic Stochastic\nRotation Dynamics (iSRD) together with Constructive Solid Geometry (CSG). The\napproach is validated by means of experimental results for the low temperature\nwater-gas shift reaction in an open-cell foam structure modeled as inverse\nsphere packing. Considering the relation between Sherwood and Reynolds number,\nwe find two distinct regimes meeting approximately at the strut size Reynolds\nnumber 10. For typical parameters from the literature, we find that the\ncatalyst density in the washcoat can be reduced considerably without a notable\nloss of conversion efficiency. We vary the porosity to determine optimum\nopen-cell foam structures, which combine low flow resistance with high\nconversion efficiency and find large porosity values to be favorable not only\nin the mass transfer limited regime but also in the intermediate regime.",
        "positive": "Identification of time scales of the violation of the Stokes-Einstein\n  relation in Yukawa liquids: We investigate the origin of the violation of the Stokes-Einstein (SE)\nrelation in two-dimensional Yukawa liquids. Using comprehensive molecular\ndynamics simulations, we identify the time scales supporting the violation of\nthe SE relation $D\\propto (\\eta/T)^{-1}$, where $D$ is the self-diffusion\ncoefficient and $\\eta$ is the shear viscosity. We first compute the\nself-intermediate scattering function $F_s(k,t)$, the non-Gaussian parameter\n$\\alpha_2$, and the autocorrelation function of the shear stress $C_{\\eta}(t)$.\nThe timescales obtained from these functions are included the structural\nrelaxation time $\\tau_{\\alpha}$, the peak time of the non-Gaussian parameter\n$\\tau_{\\alpha_2}$, and the shear stress relaxation time $\\tau_{\\eta}$. We find\nthat $\\tau_{\\eta}$ is coupled with $D$ for all temperatures indicating the SE\npreservation, however, $\\tau_{\\alpha}$ and $\\tau_{\\alpha_2}$ are decoupled with\n$D$ at low temperatures indicating the SE violation. Surprisingly, we find that\nthe origins of this violation are related to the non-exponential behavior of\nthe autocorrelation function of the shear stress and non-Gaussian behavior of\nthe distribution function of particle displacements. These results confirm\ndynamic heterogeneity that occurs in two-dimensional Yukawa liquids that\nreflects the presence of regions in which dust particles move faster than the\nrest when the liquid cools to below the phase transition temperature."
    },
    {
        "anchor": "Searching for structural predictors of plasticity in dense active\n  packings: In amorphous solids subject to shear or thermal excitation, so-called\nstructural indicators have been developed that predict locations of future\nplasticity or particle rearrangements. An open question is whether similar\ntools can be used in dense active materials, but a challenge is that under most\ncircumstances, active systems do not possess well-defined solid reference\nconfigurations. We develop a computational model for a dense active crowd\nattracted to a point of interest, which does permit a mechanically stable\nreference state in the limit of infinitely persistent motion. Previous work on\na similar system suggested that the collective motion of crowds could be\npredicted by inverting a matrix of time-averaged two-particle correlation\nfunctions. Seeking a first-principles understanding of this result, we\ndemonstrate that this active matter system maps directly onto a granular\npacking in the presence of an external potential, and extend an existing\nstructural indicator based on linear response to predict plasticity in the\npresence of noisy dynamics. We find that the strong pressure gradient\nnecessitated by the directed activity, as well as a self-generated free\nboundary, strongly impact the linear response of the system. In low-pressure\nregions the linear-response-based indicator is predictive, but it does not work\nwell in the high-pressure interior of our active packings. Our findings\nmotivate and inform future work that could better formulate structure-dynamics\npredictions in systems with strong pressure gradients.",
        "positive": "A model of friction with plastic contact nudging: Amontons-Coulomb laws,\n  aging of static friction, and non-monotonic Stribeck curves with finite\n  quasistatic limit: We introduce a model of friction between two contacting (stationary or\nco-sliding) rough surfaces, each comprising a random ensemble of polydisperse\nhemispherical bumps. In the simplest version of the model, the bumps experience\non contact with each other only pairwise elastic repulsion and dissipative\ndrag. These minimal ingredients are sufficient to capture a static state of\njammed, interlocking contacting bumps, below a critical frictional force that\nis proportional to the normal load and independent of the apparent contact\narea, consistent with the Amontons-Coulomb laws of friction. However, they fail\nto capture two widespread observations: (i) that the dynamic friction\ncoefficient (ratio of frictional to normal force in steady sliding) is a\nroughly constant or slightly weakening function of the sliding velocity $U$, at\nlow $U$, with a non-zero quasistatic limit as $U\\to 0$, and (ii) that the\nstatic friction coefficient (ratio of frictional to normal force needed to\ninitiate sliding) increases (\"ages\") as a function of the time that surfaces\nare pressed together in stationary contact, before sliding commences. To remedy\nthese shortcomings, we incorporate a single additional model ingredient: that\ncontacting bumps plastically nudge one another slightly sideways, above a\ncritical contact-contact load. With this additional insight, the model also\ncaptures observations (i) and (ii)."
    },
    {
        "anchor": "Stretching force dependent transitions in single stranded DNA: Mechanical properties of DNA, in particular their stretch dependent extension\nand their loop formation characteristics, have been recognized as an effective\nprobe for understanding the possible biochemical role played by them in a\nliving cell. Single stranded DNA (ssDNA), which, till recently was presumed to\nbe an simple flexible polymer continues to spring surprises. Synthetic ssDNA,\nlike polydA (polydeoxyadenosines) has revealed an intriguing force-extension\n(FX) behavior exhibiting two plateaus, absent in polydT (polydeoxythymidines)\nfor example. Loop closing time in polydA had also been found to scale\nexponentially with inverse temperature, unexpected from generic models of\nhomopolymers. Here we present a new model for polydA which incorporates both a\nhelix-coil transition and a over-stretching transition, accounting for the two\nplateaus. Using transfer matrix calculation and Monte-Carlo simulation we show\nthat the model reproduces different sets of experimental observations,\nquantitatively. It also predicts interesting reentrant behavior in the\ntemperature-extension characteristics of polydA, which is yet to be verified\nexperimentally.",
        "positive": "Discontinuous Jamming Transitions in Soft Materials: Many systems in nature exhibit transitions between fluid-like states and\nsolid-like states, or \"jamming transitions\". There is a strong theoretical\nfoundation for understanding equilibrium phase transitions that involve\nsolidification, or jamming. Other jamming transitions, such as the glass\ntransition, are less well-understood. The jamming phase diagram has been\nproposed to unify the description of equilibrium phase transitions, the glass\ntransitions, and other non-equilibrium jamming transitions. As with equilibrium\nphase transitions, which can either be first order (discontinuous in a relevant\norder parameter) or second order (continuous), one would expect that\ngeneralized jamming transitions can be continuous or discontinuous. In studies\nof flow in complex fluids, there is a wide range of evidence for discontinuous\ntransitions, mostly in the context of shear localization, or shear banding. In\nthis paper, I review the experimental evidence for discontinuous transitions. I\nfocus on systems in which there is a discontinuity in the rate of strain\nbetween two, coexisting states: one in which the material is flowing and the\nother in which it is solid-like."
    },
    {
        "anchor": "Vibrational properties of hard and soft spheres are unified at jamming: The unconventional thermal properties of jammed amorphous solids are directly\nrelated to their density of vibrational states. While the vibrational spectrum\nof jammed soft sphere solids has been fully described, the vibrational spectrum\nof hard spheres, a model for colloidal glasses, is still unknown due to the\ndifficulty of treating the non-analytic interaction potential. We bypass this\ndifficulty using the recently described effective interaction potential for the\nfree energy of thermal hard spheres. By minimizing this effective free energy\nwe mimic a quench and produce typical configurations of low temperature\ncolloidal glasses. We measure the resulting vibrational spectrum and\ncharacterize its evolution towards the jamming point where configurations of\nhard and soft spheres are trivially unified. For densities approaching jamming\nfrom below, we observe low frequency modes which agree with those found in\nnumerical simulations of jammed soft spheres. Our measurements of the\nvibrational structure demonstrate that the jamming universality extends away\nfrom jamming: hard sphere thermal systems below jamming exhibit the same\nvibrational spectra as thermal and athermal soft sphere systems above the\ntransition.",
        "positive": "Emergence of dynamic vortex glasses in disordered polar active fluids: In equilibrium, disorder conspires with topological defects to redefine the\nordered states of matter in systems as diverse as crystals, superconductors and\nliquid crystals. Far from equilibrium, however, the consequences of quenched\ndisorder on active condensed matter remain virtually uncharted. Here, we reveal\na state of strongly disordered active matter with no counterparts in\nequilibrium: a dynamical vortex glass. Combining high-content microfluidic\nexperiments and theory, we show how colloidal flocks collectively cruise\nthrough disorder without relaxing the topological singularities of their flows.\nThe resulting state is highly dynamical but the flow patterns, shaped by a\nfinite density of frozen vortices, are stationary and exponentially\ndegenerated. Quenched isotropic disorder acts as a random gauge field turning\nactive liquids into dynamical vortex glasses. We argue that this robust\nmechanism should shape the collective dynamics of a broad class of disordered\nactive matter, from synthetic active nematics to collections of living cells\nexploring heterogeneous media."
    },
    {
        "anchor": "Effective interactions and melting of a one dimensional defect lattice\n  within a two-dimensional confined colloidal solid: We report Monte Carlo studies of a two-dimensional soft colloidal crystal\nconfined in a strip geometry by parallel walls. The wall-particle interaction\nhas corrugations along the length of the strip. Compressing the crystal by\ndecreasing the distance between the walls induces a structural transition\ncharacterized by the sudden appearance of a one-dimensional array of extended\ndefects each of which span several lattice parameters, a \"soliton staircase\".\nWe obtain the effective interaction between these defects. A Lindemann\ncriterion shows that the reduction of dimensionality causes a finite periodic\nchain of these defects to readily melt as the temperature is raised. We discuss\npossible experimental realizations and speculate on potential applications.",
        "positive": "More on phase diagram of Laponite: The phase diagram of a charged colloidal system (Laponite) has been\ninvestigated by dynamic light scattering in a previously unexplored range of\nsalt and clay concentrations. Specifically the clay weight and salt molar\nconcentrations have been varied in the ranges Cw=0.004- 0.025, Cs=(1x 10^-3- 5x\n10^-3) M respectively. As in the case of free salt water samples (Cs= 1x 10^-4\nM) an aging dynamics towards two different arrested phases is found in the\nwhole examined Cw and Cs range. Moreover a transition between these two\ndifferent regimes is found for each investigated salt concentration. It is\nclear from these measurements that a revision of the phase diagram is necessary\nand a new \"transition\" line between two different arrested states is drawn."
    },
    {
        "anchor": "Liquid Surface Wave Band Structure Instabilities: We study interfacial instabilities between two spatially periodically sheared\nideal fluids. Bloch wavefunction decompositions of the surface deformation and\nfluid velocities result in a nonhermitian secular matrix with an associated\nband structure that yields both linear oscillating and nonoscillating\ninstabilities, enhanced near Bragg planes corresponding to the periodicity\ndetermined by converging or diverging surface flows. The instabilities persist\neven when the dynamical effects of the upper fluid are neglected, in contrast\nto the uniform shear Kelvin-Helmholtz (KH) instability. Periodic flows can also\ncouple with uniform shear and suppress standard KH instabilities.",
        "positive": "Equation of state for polymer liquid crystals: theory and experiment: The first part of this paper develops a theory for the free energy of\nlyotropic polymer nematic liquid crystals. We use a continuum model with\nmacroscopic elastic moduli for a polymer nematic phase. By evaluating the\npartition function, considering only harmonic fluctuations, we derive an\nexpression for the free energy of the system. We find that the configurational\nentropic part of the free energy enhances the effective repulsive interactions\nbetween the chains. This configurational contribution goes as the fourth root\nof the direct interactions. Enhancement originates from the coupling between\nbending fluctuations and the compressibility of the nematic array normal to the\naverage director. In the second part of the paper we use osmotic stress to\nmeasure the equation of state for DNA liquid crystals in 0.1M to 1M NaCl\nsolutions. These measurements cover 5 orders of magnitude in DNA osmotic\npressure. At high osmotic pressures the equation of state, dominated by\nexponentially decaying hydration repulsion, is independent of the ionic\nstrength. At lower pressures the equation of state is dominated by fluctuation\nenhanced electrostatic double layer repulsion. The measured equation of state\nfor DNA fits well with our theory for all salt concentrations. We are able to\nextract the strength of the direct electrostatic double layer repulsion. This\nis a new and alternative way of measuring effective charge densities along\nsemiflexible polyelectrolytes."
    },
    {
        "anchor": "Shock wave propagation in vibrofluidized granular materials: Shock wave formation and propagation in two-dimensional granular materials\nunder vertical vibration are studied by digital high speed photography. The\nsteepen density and temperature wave fronts form near the plate as granular\nlayer collides with vibrating plate and propagate upward through the layer. The\ntemperature front is always in the transition region between the upward and\ndownward granular flows. The effects of driving parameters and particle number\non the shock are also explored.",
        "positive": "Quantum phase transition in a multi-component Bose-Einstein condensate\n  in optical lattices: We present the general lattice model for a multi-component atomic\nBose-Einstein system in the optical lattice. Using the model, we analytically\nstudy the quantum phase transition between Mott insulator and superfluid. A\nmean-field theory is developed from the Mott insulator ground state. When the\ninter-species interactions are strong enough, the Mott insulator demonstrates\nthe phase separation behavior. For weak inter-species interactions, the multi\nspecies system is miscible. Finally, the phase diagram is discussed with the\nemphasis on the role of inter-species interactions. The tips of the Mott\ninsulator lobes do not depend on the inter-species interactions, but they\nindeed modify the range of lobes."
    },
    {
        "anchor": "Alignment of a topological defect by an activity gradient: As a method for controlling active materials, researchers have suggested\ndesigning patterns of activity on a substrate, which should guide the motion of\ntopological defects. To investigate this concept, we model the behavior of a\nsingle defect of topological charge $+1/2$, moving in an activity gradient.\nThis modeling uses three methods: (1) approximate analytic solution of\nhydrodynamic equations, (2) macroscopic, symmetry-based theory of the defect as\nan effective oriented particle, and (3) numerical simulation. All three methods\nshow that an activity gradient aligns the defect orientation, and hence should\nbe useful to control defect motion.",
        "positive": "Consequences of minimizing pair correlations in fluids for dynamics,\n  thermodynamics, and structure: Liquid-state theory, computer simulation, and numerical optimization are used\nto investigate the extent to which positional correlations of a hard-sphere\nfluid--as characterized by the radial distribution function and the\ntwo-particle excess entropy--can be suppressed via the introduction of\nauxiliary pair interactions. The corresponding effects of such interactions on\ntotal excess entropy, density fluctuations, and single-particle dynamics are\nexplored. Iso-g processes, whereby hard-sphere-fluid pair structure at a given\ndensity is preserved at higher densities via the introduction of a\ndensity-dependent, soft repulsive contribution to the pair potential, are\nconsidered. Such processes eventually terminate at a singular density,\nresulting in a state that--while incompressible and hyperuniform--remains\nunjammed and exhibits fluid-like dynamic properties. The extent to which static\npair correlations can be suppressed to maximize pair disorder in a fluid with\nhard cores, determined via direct functional maximization of two-body excess\nentropy, is also considered. Systems approaching a state of maximized two-body\nentropy display a progressively growing bandwidth of suppressed density\nfluctuations, pointing to a relation between \"stealthiness\" and maximal pair\ndisorder in materials."
    },
    {
        "anchor": "The explicit bonding Reaction ensemble Monte Carlo method: We present the explicit bonding Reaction ensemble Monte Carlo (eb-RxMC)\nmethod, designed to sample reversible bonding reactions in macromolecular\nsystems. Our eb-RxMC differs from the original Reaction ensemble method by\nexplicitly adding or deleting bonds between the reactive particles, instead of\nexchanging particles with the virtual reservoir. Our eb-RxMC algorithm is\nbiased to sample only the reaction within an inclusion radius, which allows to\ncouple it with Molecular Dynamics algorithm to sample the reaction and\nconfiguration space concomitantly. We validate our algorithm for a set of\nideally behaving systems undergoing dimerization and polycondensation\nreactions, for which analytical results are available. Namely, we showed that\nfor dimerization reactions with different equilibrium constant and initial\ncompositions, the degree of conversion measured in our simulations perfectly\nmatched the reference value given by the analytical equations, irrespective of\nthe choice of the inclusion radius or the stiffness of the harmonic potential.\nNext, we showed that our simulations can correctly match the analytical results\nfor the chain length distribution and end-to-end distance of ideal chains in\npolycondensation reactions. Altogether, we show that our eb-RxMC simulations\ncorrectly sample both the reaction and the configuration space of these\nreference systems, opening the door to future simulations of more complex\ninteracting macromolecular systems.",
        "positive": "Yield Stress Materials in Soft Condensed Matter: We present a comprehensive review of the physical behavior of yield stress\nmaterials in soft condensed matter, which encompass a broad range of materials\nfrom colloidal assemblies and gels to emulsions and non-Brownian suspensions.\nAll these disordered materials display a nonlinear flow behavior in response to\nexternal mechanical forces, due to the existence of a finite force threshold\nfor flow to occur: the yield stress. We discuss both the physical origin and\nrheological consequences associated with this nonlinear behavior, and give an\noverview of experimental techniques available to measure the yield stress. We\ndiscuss recent progress concerning a microscopic theoretical description of the\nflow dynamics of yield stress materials, emphasizing in particular the role\nplayed by relaxation time scales, the interplay between shear flow and aging\nbehavior, the existence of inhomogeneous shear flows and shear bands, wall\nslip, and non-local effects in confined geometries."
    },
    {
        "anchor": "Interpenetrated biosurfactant-biopolymer orthogonal hydrogels: the\n  biosurfactant's phase controls the hydrogel's mechanics: Controlling the viscoelastic properties of hydrogels is a challenge for many\napplications. Low molecular weight gelators (LMWG) like bile salts and\nglycolipids, and biopolymers like chitosan and alginate, are good candidates\nfor developing fully biobased hybrid hydrogels that combine the advantages of\nboth components. Biopolymers lead to enhanced mechanics while LMWG add\nfunctionality. In this work, hybrid hydrogels are composed of biopolymers\n(gelatin, chitosan, alginate) and microbial glycolipid bioamphiphiles, known as\nbiosurfactants. Besides their biocompatibility and natural origin,\nbioamphiphiles can present chameleonic behavior, as pH and ions control their\nphase diagram in water around neutrality under strongly diluted conditions (< 5\nwt%). The glycolipid used in this work behaves like a surfactant (micellar\nphase) at high pH or like a phospholipid (vesicle phase) at low pH. Moreover,\nat neutral-to-alkaline pH in the presence of calcium, it behaves like a gelator\n(fiber phase). The impact of each of these phases on the elastic properties of\nbiopolymers is explored by means of oscillatory rheology, while the hybrid\nstructure is studied by small angle X-ray scattering. The micellar and\nvesicular phase reduce the elastic properties of the hydrogels, while the fiber\nphase has the opposite effect, it enhances the hydrogel's strength by forming\nan interpenetrated biopolymer-LMWG network.",
        "positive": "Probe particles in odd active viscoelastic fluids: how activity and\n  dissipation determine linear stability: Odd viscoelastic materials are constrained by fewer symmetries than their\neven counterparts. The breaking of these symmetries allow these materials to\nexhibit different features, which have attracted considerable attention in\nrecent years. Immersing a bead in such complex fluids allows for probing their\nphysical properties, highlighting signatures of their oddity and exploring\nconsequences of these broken symmetries. We present the conditions under which\nthe activity of an odd viscoelastic fluid can give rise to linear instabilities\nin the motion of the probe particle and unveil how the features of the probe\nparticle dynamics depend on the oddity and activity of the viscoelastic medium\nin which it is immersed."
    },
    {
        "anchor": "Segregation of receptor-ligand complexes in cell adhesion zones: Phase\n  diagrams and role of thermal membrane roughness: The adhesion zone of immune cells, the 'immunological synapse', exhibits\ncharacteristic domains of receptor-ligand complexes. The domain formation is\nlikely caused by a length difference of the receptor-ligand complexes, and has\nbeen investigated in experiments in which T cells adhere to supported membranes\nwith anchored ligands. For supported membranes with two types of anchored\nligands, MHCp and ICAM1, that bind to the receptors TCR and LFA1 in the cell\nmembrane, the coexistence of domains of TCR-MHCp and LFA1-ICAM1 complexes in\nthe cell adhesion zone has been observed for a wide range of ligand\nconcentrations and affinities. For supported membranes with long and short\nligands that bind to the same cell receptor CD2, in contrast, domain\ncoexistence has been observed for a rather narrow ratio of ligand\nconcentrations. In this article, we determine detailed phase diagrams for cells\nadhering to supported membranes with a statistical-physical model of cell\nadhesion. We find a characteristic difference between the adhesion scenarios in\nwhich two types of ligands in a supported membrane bind (i) to the same cell\nreceptor or (ii) to two different cell receptors, which helps to explain the\nexperimental observations. Our phase diagrams fully include thermal shape\nfluctuations of the cell membranes on nanometer scales, which lead to a\ncritical point for the domain formation and to a cooperative binding of the\nreceptors and ligands.",
        "positive": "Growth-induced blisters in a circular tube: The growth of an elastic film adhered to a confining substrate might lead to\nthe formation of delimitation blisters. Many results have been derived when the\nsubstrate is flat. The equilibrium shapes, beyond small deformations, are\ndetermined by the interplay between the sheet elastic energy and the adhesive\npotential due to capillarity. Here, we study a non-trivial generalization to\nthis problem and consider the adhesion of a growing elastic loop to a confining\n\\emph{circular} substrate. The fundamental equations, i.e., the Euler Elastica\nequation, the boundary conditions and the transversality condition, are derived\nfrom a variational procedure. In contrast to the planar case, the curvature of\nthe delimiting wall appears in the transversality condition, thus acting as a\nfurther source of adhesion. We provide the analytic solution to the problem\nunder study in terms of elliptic integrals and perform the numerical and the\nasymptotic analysis of the characteristic lengths of the blister. Finally, and\nin contrast to previous studies, we also discuss the mechanics and the internal\nstresses in the case of vanishing adhesion. Specifically, we give a theoretical\nexplanation to the observed divergence of the mean pressure exerted by the\nstrip on the container in the limit of small excess-length."
    },
    {
        "anchor": "On the product selectivity in the electrochemical reductive cleavage of\n  lignin model compounds: Research towards the production of renewable chemicals for fuel and energy\nindustries has found lignin valorization as key. With a high carbon content and\naromaticity, a fine-tuning of the depolymerization process is required to\nconvert lignin into valuable chemicals. In context, model compounds have been\nused to understand the electrocatalyzed depolymerization for mimicking the\ntypical linkages of lignin. In this investigation, 2-phenoxyacetophenone, a\nmodel compound for lignin \\b{eta}-O-4 linkage, was electro-catalytically\nhydrogenated (ECH) in distinct three-electrode setups: an open and a membrane\ncell. A deep eutectic solvent based on ethylene-glycol and choline chloride was\nused to pursue sustainable routes to dissolve lignin. Copper was used as\nelectrocatalyst due to the economic feasibility and low activity towards\nhydrogen evolution reaction (HER), a side reaction of ECH. By varying the cell\ntype, we demonstrate a simple ECH route for the generation of different\nmonomers and oligomers from lignin. Gas chromatography of the products revealed\na higher content of carbonyl groups in those using the membrane cell, whereas\nthe open cell produced mostly hydroxyl-end chemicals. Aiming at high\nvalue-added products, our results disclose the cell type influence on\nelectrochemical reductive depolymerization of lignin. This approach encompasses\ncheap transition metal electrodes and sustainable solvents.",
        "positive": "Transport in hybrid electronic devices based on a modified DNA\n  nucleoside (deoxyguanosine): We report on a new class of hybrid electronic devices based on a DNA\nnucleoside (deoxyguanosine lipophilic derivative) whose assembled polymeric\nribbons interconnect a submicron metallic gate. The device exhibits large\nconductivity at room temperature, rectifying behaviour and strong\ncurrent-voltage hysteresis. The transport mechanism through the molecules is\ninvestigated by comparing films with different self-assembling morphology. We\nfound that the main transport mechanism is connected to pi-pi interactions\nbetween guanosine molecules in adjacent ribbons, consistently with the results\nof our first-principles calculations."
    },
    {
        "anchor": "A note on rattlers in amorphous packings of binary mixtures of hard\n  spheres: It has been recently pointed out by Farr and Groot (arXiv:0912.0852) and by\nKyrylyuk and Philipse (Prog. Colloid Polym. Sci., 2010, in press) that our\ntheoretical result for the jamming density of a binary mixture of hard spheres\n(arXiv:0903.5099) apparently violates an upper bound that is obtained by\nconsidering the limit where the diameter ratio r = DA/DB goes to infinity. We\nbelieve that this apparent contradiction is the consequence of a\nmisunderstanding, which we try to clarify here.",
        "positive": "Transient behaviour of a polymer dragged through a viscoelastic medium: We study the dynamics of a polymer that is pulled by a constant force through\na viscoelastic medium. This is a model for a polymer being pulled through a\ncell by an external force, or for an active biopolymer moving due to a self\ngenerated force. Using a Rouse model with a memory dependent drag force, we\nfind that the center of mass of the polymer follows a subballistic motion. We\ndetermine the time evolution of the length and the shape of the polymer.\nThrough an analysis of the velocity of the monomers, we investigate how the\ntension propagates through the polymer. We discuss how polymers can be used as\na probe of the properties of a viscoelastic medium."
    },
    {
        "anchor": "Analysis of Granular Flow in a Pebble-Bed Nuclear Reactor: Pebble-bed nuclear reactor technology, which is currently being revived\naround the world, raises fundamental questions about dense granular flow in\nsilos. A typical reactor core is composed of graphite fuel pebbles, which drain\nvery slowly in a continuous refueling process. Pebble flow is poorly understood\nand not easily accessible to experiments, and yet it has a major impact on\nreactor physics. To address this problem, we perform full-scale,\ndiscrete-element simulations in realistic geometries, with up to 440,000\nfrictional, viscoelastic 6cm-diameter spheres draining in a cylindrical vessel\nof diameter 3.5m and height 10m with bottom funnels angled at 30 degrees or 60\ndegrees. We also simulate a bidisperse core with a dynamic central column of\nsmaller graphite moderator pebbles and show that little mixing occurs down to a\n1:2 diameter ratio. We analyze the mean velocity, diffusion and mixing, local\nordering and porosity (from Voronoi volumes), the residence-time distribution,\nand the effects of wall friction and discuss implications for reactor design\nand the basic physics of granular flow.",
        "positive": "Synergistic interactions between DNA and actin trigger emergent\n  viscoelastic behavior: Composites of flexible and rigid polymers are ubiquitous in biology and\nindustry alike, yet the physical principles determining their mechanical\nproperties are far from understood. Here, we couple force spectroscopy with\nlarge-scale Brownian Dynamics simulations to elucidate the unique viscoelastic\nproperties of custom-engineered blends of entangled flexible DNA molecules and\nsemiflexible actin filaments. We show that composites exhibit enhanced\nstress-stiffening and prolonged mechano-memory compared to systems of actin or\nDNA alone, and that these nonlinear features display a surprising non-monotonic\ndependence on the fraction of actin in the composite. Simulations reveal that\nthese counterintuitive results arise from synergistic microscale interactions\nbetween the two biopolymers. Namely, DNA entropically drives actin filaments to\nform bundles that stiffen the network but reduce the entanglement density,\nwhile a percolating actin network is required to reinforce the DNA network\nagainst yielding and flow. The competition between bundling and percolation\ntriggers an unexpected stress response that leads equal mass actin-DNA\ncomposites to exhibit the most pronounced stress-stiffening and the most\nlong-lived entanglements."
    },
    {
        "anchor": "Drop-on-coilable-fibre systems exhibit negative stiffness events and\n  transitions in coiling morphology: We investigate the mechanics of elastic fibres carrying liquid droplets. In\nsuch systems, buckling may localize inside the drop cavity if the fibre is thin\nenough. This so-called drop-on-coilable-fibre system exhibits a surprising\nliquid-like response under compression, and a solid-like response under\ntension. Here we analyze this unconventional behavior in further details and\nfind theoretical, numerical and experimental evidences of negative stiffness\nevents. We find that the first and main negative stiffness regime owes its\nexistence to the transfer of capillary-stored energy into mechanical curvature\nenergy. The following negative stiffness events are associated with changes in\nthe coiling morphology of the fibre. Eventually coiling becomes tightly locked\ninto an ordered phase where liquid and solid deformations coexist.",
        "positive": "Simulation and Theory of Ions at Atmospherically Relevant Aqueous\n  Liquid-Air Interfaces: Chemistry occurring at or near the surfaces of aqueous droplets and thin\nfilms in the atmosphere influences air quality and climate. Molecular dynamics\nsimulations are becoming increasingly useful for gaining atomic-scale insight\ninto the structure and reactivity of aqueous interfaces in the atmosphere. Here\nwe review simulation studies of atmospherically relevant aqueous liquid-air\ninterfaces, with an emphasis on ions that play important roles in the chemistry\nof atmospheric aerosols. In addition to surveying results from simulation\nstudies, we discuss challenges to the refinement and experimental validation of\nthe methodology for simulating ion adsorption to the air-water interface, and\nrecent advances in elucidating the driving forces for adsorption. We also\nreview the recent development of a dielectric continuum theory that is capable\nof reproducing simulation and experimental data on ion behavior at aqueous\ninterfaces."
    },
    {
        "anchor": "Foundations of viscoelasticity and application to soft tissues mechanics: Soft tissues are complex media, they display a wide range of mechanical\nproperties such as anisotropy and non-linear stress-strain behaviour. They\nundergo large deformations and they exhibit a time-dependent mechanical\nbehaviour, i.e. they are viscoelastic. In this chapter we review the\nfoundations of the linear viscoelastic theory and the theory of Quasi-Linear\nViscoelasticity (QLV) in view of developing new methods to estimate the\nviscoelastic properties of soft tissues through model fitting. To this aim, we\nconsider the simple torsion of a viscoelastic Mooney-Rivlin material in two\ndifferent testing scenarios: step-strain and ramp tests. These tests are\ncommonly performed to characterise the time-dependent properties of soft\ntissues and allow to investigate their stress relaxation behaviour. Moreover,\ncommercial torsional rheometers measure both the torque and the normal force,\ngiving access to two sets of data. We show that for a step test, the linear and\nthe QLV models predict the same relaxation curves for the torque. However, when\nthe strain history is in the form of a ramp function, the non-linear terms\nappearing in the QLV model affect the relaxation curve of the torque depending\non the final strain level and on the rising time of the ramp. Furthermore, our\nresults show that the relaxation curve of the normal force predicted by the QLV\ntheory depends on the level of strain both for a step and a ramp tests. To\nquantify the effect of the non-linear terms, we evaluate the maximum and the\nequilibrium values of the relaxation curves. Our results provide useful\nguidelines to accurately fit QLV models in view of estimating the viscoelastic\nproperties of soft tissues.",
        "positive": "Stiff polymer in monomer ensemble: We make use of the previously developed formalism for a monomer ensemble and\ninclude angular dependence of the segments of the polymer chains thus\ndescribed. In particular we show how to deal with stiffness when the polymer\nchain is confined to certain regions. We investigate the stiffness from the\nperspectives of a differential equation, integral equations, or recursive\nrelations for both continuum and lattice models. Exact analytical solutions are\npresented for two cases, whereas numerical results are shown for a third case."
    },
    {
        "anchor": "Tuning brittleness in multi-component metallic glasses through chemical\n  disorder aging: Shear localization in slowly-driven bulk metallic glasses (BMGs) is typically\naccompanied by a sharp drop in the bulk stress response as a signature of the\nplastic yielding transition. It is also observed that the sharpness of this\nelastic-plastic dynamical transition depends on the extent of local chemical\nand microstructural orders, as well as the glass preparation protocol ( ie.\nthermal annealing). Here, we investigate sheared multi-element BMGs in\nmolecular dynamics (MD) simulations, and demonstrate that glass aging,\nimplemented through a hybrid Monte-Carlo(MC)-MD process, sharpens the\nelastic-plastic transition through a distinct crossover, seen in strain\npatterns that gradually shift from diffuse features in as-quenched samples to\nlocalized (yet system-spanning) patterns in well-annealed glasses. This effect\nof glass aging on the elastic-plastic transition is found to be correlated to\nthe inherent interplay between aging-induced icosahedra ordering and\nco-operative formation of shear transformation zones. The observed crossover is\nquantified through a measure of the age-dependent susceptibility to plastic\nrearrangements, exhibiting strong (anti-)correlations to local ordering\nfeatures, and the corresponding spatial correlation length grows with the aging\ntimescale.",
        "positive": "Bistable collective behavior of polymers tethered in a nanopore: Polymer-coated pores play a crucial role in nucleo-cytoplasmic transport and\nin a number of biomimetic and nanotechnological applications. Here we present\nMonte Carlo and Density Functional Theory approaches to identify different\ncollective phases of end-grafted polymers in a nanopore and to study their\nrelative stability as a function of intermolecular interactions. Over a range\nof system parameters that is relevant for nuclear pore complexes, we observe\ntwo distinct phases: one with the bulk of the polymers condensed at the wall of\nthe pore, and the other with the polymers condensed along its central axis. The\nrelative stability of these two phases depends on the interpolymer\ninteractions. The existence of the two phases suggests a transport mechanism in\nwhich marginal changes in these interactions, possibly induced by nuclear\ntransport receptors, cause the pore to transform between open and closed\nconfigurations."
    },
    {
        "anchor": "Phase diagram of solution of oppositely charged polyelectrolytes: We study a solution of long polyanions (PA) with shorter polycations (PC) and\nfocus on the role of Coulomb interaction. A good example is solutions of DNA\nand PC which are widely studied for gene therapy. In the solution, each PA\nattracts many PCs to form a complex. When the ratio of total charges of PA and\nPC in the solution, $x$, equals to 1, complexes are neutral and they condense\nin a macroscopic drop. When $x$ is far away from 1, complexes are strongly\ncharged. The Coulomb repulsion is large and free complexes are stable. As $x$\napproaches to 1, PCs attached to PA disproportionate themselves in two\ncompeting ways. One way is inter-complex disproportionation, in which PCs make\nsome complexes neutral and therefore condensed in a macroscopic drop while\nother complexes become even stronger charged and stay free. The other way is\nintra-complex disproportionation, in which PCs make one end of a complex\nneutral and condensed in a small droplet while the rest of the complex forms a\nstrongly charged tail. Thus each complex becomes a \"tadpole\". These two ways\ncan also combine together to give even lower free energy. We get a phase\ndiagram of PA-PC solution in a plane of $x$ and inverse screening radius of the\nmonovalent salt, which includes phases or phase coexistence with both kinds of\ndisproportionation.",
        "positive": "Long-range excitons in conjugated polymers with ring torsions:\n  poly(para-phenylene) and polyaniline: Ring torsion effects on optical excitation properties in poly(para-phenylene)\n(PPP) and polyaniline (PAN) are investigated by extending the Shimoi-Abe model\n[Synth. Met. 78, 219 (1996)]. The model is solved by the intermediate exciton\nformalism. Long-range excitons are characterized, and the long-range component\nof the oscillator strengths is calculated. We find that ring torsions affect\nthe long-range excitons in PAN more easily than in PPP, due to the larger\ntorsion angle of PAN and the large number of bonds whose hopping integrals are\nmodulated by torsions. Next, ring torsional disorder effects simulated by the\nGaussian distribution function are analyzed. The long-range component of the\ntotal oscillator strengths after sample average is nearly independent of the\ndisorder strength in the PPP case, while that of the PAN decreases easily as\nthe disorder becomes stronger."
    },
    {
        "anchor": "Morphological Control of Bundled Actin Networks Subject to Fixed-Mass\n  Depletion: Depletion interactions are thought to significantly contribute to the\norganization of intracellular structures in the crowded cytosol. The strength\nof depletion interactions depends on physical parameters like the depletant\nnumber density and the depletant size ratio. Cells are known to dynamically\nregulate these two parameters by varying the copy number of proteins of a wide\ndistribution of sizes. However, mammalian cells are also known to keep the\ntotal protein mass density remarkably constant, to within 0.5% throughout the\ncell cycle. We thus ask how the strength of depletion interactions varies when\nthe total depletant mass is held fixed, a.k.a. fixed-mass depletion. We answer\nthis question via scaling arguments, as well as by studying depletion effects\non networks of reconstituted semiflexible actin $\\textit{in silico}$ and\n$\\textit{in vitro}$. We examine the maximum strength of the depletion\ninteraction potential $U^*$ as a function of $q$, the size ratio between the\ndepletant and the matter being depleted. We uncover a scaling relation $U^*\n\\sim q^{-\\zeta}$ for two cases: fixed volume fraction $\\phi$ and fixed mass\ndensity $\\rho$. For fixed volume fraction, we report $\\zeta < 0$. For the fixed\nmass density case, we report $\\zeta > 0$, which suggests the depletion\ninteraction strength increases as the depletant size ratio is increased. To\ntest this prediction, we prepared our filament networks at fixed mass\nconcentrations with varying sizes of the depletant molecule poly(ethylene\nglycol) (PEG). We characterize the depletion interaction strength in our\nsimulations via the mesh size. In experiments, we observe two distinct actin\nnetwork morphologies, which we call weakly bundled and strongly bundled. We\nidentify a mass concentration where different PEG depletant sizes leads to\nweakly bundled or strongly bundled morphologies...[more in main text].",
        "positive": "Geometric Thermodynamics of Strain-Induced Crystallization in Polymers: Going beyond the classical Gaussian approximation of Einstein's fluctuation\ntheory, Ruppeiner gave it a Riemannian geometric structure with an entropic\nmetric. This yielded a fundamental quantity - the Riemannian curvature, which\nwas used to extract information on the nature of interactions between molecules\nin fluids, ideal gases and other open systems. In this article, we examine the\nimplications of this curvature in a non-equilibrium thermodynamic system where\nrelaxation is sufficiently slow so as not to invalidate the local equilibrium\nhypothesis. The non-equilibrium system comprises of a rubbery polymer\nundergoing strain induced crystallization. The curvature is found to impart\ninformation on a spurious isochoric energy arising from the conformational\nstretching of already crystallized segments. This unphysical component perhaps\narises as the crystallized manifold is considered Euclidean with the stretch\nmeasures defined via the Euclidean metric. The thermodynamic state associated\nwith curvature is the key to determine the isochoric stretch and hence the\nspurious energy. We determine this stretch and propose a form for the spurious\nfree energy that must be removed from the total energy in order that the\ncorrect stresses are recovered."
    },
    {
        "anchor": "Slip flow regimes in nanofluidics: a universal superexponential model: Many experiments have shown large flow enhancement ratios (up to 10^5) in\ncarbon nanotubes (CNT) with diameters larger than 5nm. However, molecular\ndynamics simulations have never replicated these results maintaining a\nthree-order-of-magnitude gap with measurements. Our study provides a generic\nmodel of nanofluidics for continuum slip flow (diameter>3nm) that fills this\nsignificant gap and sheds light on its origin. Compared to 140 literature\ncases, the model explains the entire range of experimental flow enhancements by\nchanges of nanotube diameters and finite variations of interfacial energies.\nDespite large variations of flow enhancement ratios spanning 5 orders of\nmagnitude in experimental results, the ratio between these data and\ncorresponding model predictions approaches unity for the majority of\nexperiments. The role of viscous entrance effects is discussed. The model\nprovides insight into puzzling observations such as differences of CNTs and\nboron nitride nanotubes, the slip on low-contact-angle surfaces and massive\nfunctionalization effects. This study could advance our understanding of\nnano-scale transport mechanisms and aid the design of tailored nanomembranes.",
        "positive": "Stochastic Model in the Kardar-Parisi-Zhang Universality With Minimal\n  Finite Size Effects: We introduce a solid on solid lattice model for growth with conditional\nevaporation. A measure of finite size effects is obtained by observing the time\ninvariance of distribution of local height fluctuations. The model parameters\nare chosen so that the change in the distribution in time is minimum.\n  On a one dimensional substrate the results obtained from the model for the\nroughness exponent $\\alpha$ from three different methods are same as predicted\nfor the Kardar-Parisi-Zhang (KPZ) equation. One of the unique feature of the\nmodel is that the $\\alpha$ as obtained from the structure factor $S(k,t)$ for\nthe one dimensional substrate growth exactly matches with the predicted value\nof 0.5 within statistical errors. The model can be defined in any dimensions.\nWe have obtained results for this model on a 2 and 3 dimensional substrates."
    },
    {
        "anchor": "Rheology of dense suspensions of ideally conductive particles in an\n  electric field: The rheological behaviour of dense suspensions of ideally conductive\nparticles in the presence of both electric field and shear flow is studied\nusing large-scale numerical simulations. Under the action of an electric field,\nthese particles are known to undergo dipolophoresis, which is the combination\nof two nonlinear electrokinetic phenomena -- induced-charge electrophoresis and\ndielectrophoresis. For ideally conductive particles, induced-charge\nelectrophoresis is predominant over dielectrophoresis, resulting in transient\npairing dynamics. The shear viscosity and first and second normal stress\ndifferences $N_1$ and $N_2$ of such suspensions are examined over a range of\nvolume fractions $15\\% \\leqslant \\phi \\leqslant 50\\%$ as a function of Mason\nnumber $Mn$, which measures the relative importance of viscous shear stress\nover electrokinetic-driven stress. For $Mn < 1$ or low shear rates, the\ndipolophoresis is shown to dominate the dynamics, resulting in a relatively\nlow-viscosity state. The positive $N_1$ and negative $N_2$ are observed at\n$\\phi < 30\\%$, which is similar to Brownian suspensions, while their signs are\nreversed at $\\phi \\ge 30\\%$. For $Mn \\ge 1$, the shear thickening starts to\narise at $\\phi \\ge 30\\%$, and an almost five-fold increase in viscosity occurs\nat $\\phi = 50\\%$. Both $N_1$ and $N_2$ are negative for $Mn \\gg 1$ at all\nvolume fractions considered. We illuminate the transition in rheological\nbehaviours from dipolophoresis to shear dominance around $Mn = 1$ in connection\nto suspension microstructure and dynamics. Lastly, our findings reveal the\npotential use of nonlinear electrokinetics as a means of active rheology\ncontrol for such suspensions.",
        "positive": "Temporal evolution of interparticle potentials of PMMA colloids in\n  CHB/decaline: Colloidal dispersions composed of polymethylmetacrylate particles dispersed\nin a mixture of cyclohexylbromide and decalin find widespread use as model\nsystems in optical microscopy experiments. While the system allows simultaneous\ndensity and refractive index matching, preparing particles with hard potentials\nremains challenging and strong variations in the physical parameters of samples\nprepared in the same manner are common. Here, we present data on the\nmeasurement of forces between individual pairs of particles over the course of\ntens of days using a blinking optical tweezer method. Our results show that the\nvariations in the particle properties are indeed caused by a temporal evolution\nof the particles' charging. Additional measurements of the influence of\ntetrabutylammonium bromide (TBAB) addition to the dispersions show that already\nsmall concentrations of added TBAB drastically decrease the electrostatic\nforces between colloidal particles. However, small, non-negligible contact\npotentials remain even at the highest TBAB concentrations added."
    },
    {
        "anchor": "The Johnson-Segalman model with a diffusion term in Couette flow: We study the Johnson-Segalman (JS) model as a paradigm for some complex\nfluids which are observed to phase separate, or ``shear-band'' in flow. We\nanalyze the behavior of this model in cylindrical Couette flow and demonstrate\nthe history dependence inherent in the local JS model. We add a simple gradient\nterm to the stress dynamics and demonstrate how this term breaks the degeneracy\nof the local model and prescribes a much smaller (discrete, rather than\ncontinuous) set of banded steady state solutions. We investigate some of the\neffects of the curvature of Couette flow on the observable steady state\nbehavior and kinetics, and discuss some of the implications for metastability.",
        "positive": "Statistical mechanics of a dielectric polymer chain in the force\n  ensemble: Constitutive modeling of dielectric elastomers has been of long standing\ninterest in mechanics. Over the last two decades rigorous constitutive models\nhave been developed that couple the electrical response of these polymers with\nlarge deformations characteristic of soft solids. A drawback of these models is\nthat unlike classic models of rubber elasticity they do not consider the\ncoupled electromechanical response of single polymer chains which must be\ntreated using statistical mechanics. The objective of this paper is to compute\nthe stretch and polarization of single polymer chains subject to a fixed force\nand fixed electric field using statistical mechanics. We assume that the\ndipoles induced by the applied electric field at each link do not interact with\neach other and compute the partition function using standard techniques. We\nthen calculate the stretch and polarization by taking appropriate derivatives\nof the partition function and obtain analytical results in various limits. We\nalso perform Markov chain Monte Carlo simulations using the Metropolis and\numbrella sampling methods, as well as develop a new sampling method which\nimproves convergence by exploiting a symmetry inherent in dielectric polymer\nchains. The analytical expressions are shown to agree with the Monte Carlo\nresults over a range of forces and electric fields. Our results complement\nrecent work on the statistical mechanics of electro-responsive chains which\nobtains analytical expressions in a different ensemble."
    },
    {
        "anchor": "Anomalous diffusion of phospholipids and cholesterols in a lipid bilayer\n  and its origins: Combining extensive molecular dynamics simulations of lipid bilayer systems\nof varying chemical composition with single-trajectory analyses we\nsystematically elucidate the stochastic nature of the lipid motion. We observe\nsubdiffusion over more than four orders of magnitude in time, clearly\nstretching into the sub-microsecond domain. The lipid motion delicately depends\non the lipid chemistry, the lipid phase, and especially on the presence of\ncholesterol. We demonstrate that fractional Langevin equation motion\nuniversally describes the lipid motion in all phases including the gel phase,\nand in the presence of cholesterol. The results underline the relevance of\nanomalous diffusion in lipid bilayers and the strong effects of the membrane\ncomposition.",
        "positive": "Energy Driven Pattern Formation in Planar Dipole-Dipole Systems in the\n  Presence of Weak Noise: We study pattern formation in planar fluid systems driven by intermolecular\ncohesion (which manifests as a line tension) and dipole-dipole repulsion which\nare observed in physical systems including ferrofluids in Hele-Shaw cells and\nLangmuir layers. When the dipolar repulsion is sufficiently strong, domains\nundergo forked branching reminiscent of viscous fingering. A known difficulty\nwith these models is that the energy associated with dipole-dipole interactions\nis singular at small distances. Following previous work, we demonstrate how to\nameliorate this singularity and show that in the macroscopic limit, only the\nrelative scale of the microscopic details of a system are relevant, and develop\nan expression for the system energy that depends only on a generalized line\ntension, {\\Lambda}, that in turn depends logarithmically on that scale. We\nconduct numerical studies that use energy minimization to find equilibrium\nstates. Following the subcritical bifurcations from the circle, we find a few\nhighly symmetric stable shapes, but nothing that resembles the observed\ndiversity of experimental and dynamically simulated domains. The application of\na weak random background to the energy landscape stabilizes a sm\\\"org\\r{a}sbord\nof domain morphologies recovering the diversity observed experimentally. With\nthis technique, we generate a large sample of qualitatively realistic shapes\nand use them to create an empirical model for extracting {\\Lambda} using only a\nshape's perimeter and morphology with high accuracy."
    },
    {
        "anchor": "Compositional and orientational ordering in rod-coil diblock copolymer\n  melts: The phase behavior of a melt of monodisperse rod-coil diblocks is studied. We\nderive a Landau free energy functional for both a compositional and a nematic\norder parameter. The excluded volume interaction between the rod blocks is\nmodeled by an attractive Maier-Saupe interaction. The incompatibility between\nrod- and coil blocks is modeled by the usual Flory-Huggins interaction. For a\nlarge volume fraction of the rods, a transition from isotropic to nematic to\nsmectic C is observed upon decreasing the temperature, whereas for small rod\nvolume fraction, spherical, hexagonal, and lamellar structures prevail. In the\nsmectic C phase, the rod orientation angle with respect to the lamellar normal\nincreases rapidly from 35 to 40 degrees close to the nematic/smectic-C phase\nboundary to values between 45 and 55 degrees.",
        "positive": "Avalanches in the athermal quasistatic limit of sheared amorphous\n  solids: an atomistic perspective: We study the statistical properties of the yielding transition in model\namorphous solids in the limit of slow, athermal deformation. Plastic flow\noccurs via alternating phases of elastic loading punctuated by rapid\ndissipative events in the form of collective avalanches. We investigate their\ncharacterization through energy vs. stress drops and at multiple stages of\ndeformation, thus revealing a change of spatial extent of the avalanches and\ndegree of stress correlations as deformation progresses. We show that the\nstatistics of stress and energy drops only become comparable for large events\nin the steady flow regime. Results for the critical exponents of the yielding\ntransition are discussed in the context of prior studies of similar type,\nrevealing the influence of model glass and preparation history."
    },
    {
        "anchor": "Direct observation and rational design of nucleation behavior in\n  addressable self-assembly: In order to optimize a self-assembly reaction, it is essential to understand\nthe factors that govern its pathway. Here, we examine the influence of\nnucleation pathways in a model system for addressable, multicomponent\nself-assembly based on a prototypical 'DNA-brick' structure. By combining\ntemperature-dependent dynamic light scattering and atomic force microscopy with\ncoarse-grained simulations, we show how subtle changes in the nucleation\npathway profoundly affect the yield of the correctly formed structures. In\nparticular, we can increase the range of conditions over which self-assembly\noccurs by utilizing stable multi-subunit clusters that lower the nucleation\nbarrier for assembling subunits in the interior of the structure. Consequently,\nmodifying only a small portion of a structure is sufficient to optimize its\nassembly. Due to the generality of our coarse-grained model and the excellent\nagreement that we find with our experimental results, the design principles\nreported here are likely to apply generically to addressable, multicomponent\nself-assembly.",
        "positive": "Active nematics on a substrate: giant number fluctuations and long-time\n  tails: We construct the equations of motion for the coupled dynamics of order\nparameter and concentration for the nematic phase of driven particles on a\nsolid surface, and show that they imply (i) giant number fluctuations, with a\nstandard deviation proportional to the mean and (ii) long-time tails $\\sim\nt^{-d/2}$ in the autocorrelation of the particle velocities in $d$ dimensions\ndespite the absence of a hydrodynamic velocity field. Our predictions can be\ntested in experiments on aggregates of amoeboid cells as well as on layers of\nagitated granular matter."
    },
    {
        "anchor": "Dynamics of a Bilayer Membrane Coupled to a Two-dimensional\n  Cytoskeleton: Scale Transfers of Membrane Deformations: We theoretically investigate the dynamics of a floating lipid bilayer\nmembrane coupled with a two-dimensional cytoskeleton network, taking into\nexplicitly account the intermonolayer friction, the discrete lattice structure\nof the cytoskeleton, and its prestress. The lattice structure breaks lateral\ncontinuous translational symmetry and couples Fourier modes with different\nwavevectors. It is shown that within a short time interval a long-wavelength\ndeformation excites a collection of modes with wavelengths shorter than the\nlattice spacing. These modes relax slowly with a common renormalized rate\noriginating from the long-wavelength mode. As a result, and because of the\nprestress, the slowest relaxation is governed by the intermonolayer friction.\nReversely, and most interestingly, forces applied at the scale of the\ncytoskeleton for a sufficiently long time can cooperatively excite large-scale\nmodes.",
        "positive": "Rheology of active emulsions with negative effective viscosity: We numerically study by lattice Boltzmann simulations the rheological\nproperties of an active emulsion made of a suspension of an active polar gel\nembedded in an isotropic passive background. We find that the hexatic\nequilibrium configuration of polar droplets is highly sensitive to both active\ninjection and external forcing and may either lead to asymmetric unidirectional\nstates which break top-bottom symmetry or symmetric ones. In this latter case,\nfor large enough activity, the system develops a shear-thickening regime at low\nshear rates. Importantly, for larger external forcing a regime with stable\nnegative effective viscosity is found. Moreover, at intermediate activity a\nregion of multistability is encountered and we show that a maximum entropy\nproduction principle holds in selecting the most favorable state."
    },
    {
        "anchor": "Size polydisperse model Ionic Liquid in bulk: The static and the dynamic properties of a size-polydisperse model ionic\nliquid is studied using molecular dynamics simulations. Here, size of the\nanions is derived from a Gaussian distribution while keeping cation size fixed,\nresulting in a system that closely corresponds to IL mixtures with a common\ncation. We systematically explore the behavior of thermodynamic transition\ntemperatures, spatial ordering of ions and the resulting screening behavior as\na function of polydispersity index, $\\delta$. We observe a non-monotonic\ndependence of transition temperatures on $\\delta$, and this non-monotonic\nbehaviour is also reflected in other properties such as screening length.\nFurthermore, from the radial distribution function analysis it is found that,\nupon varying $\\delta$, the spatial ordering of cations is affected, while no\nsuch changes is seen for anion. On the other hand, the analysis of ion motion\nthrough mean-square displacement show that for all $\\delta$ values considered\nboth inertial and diffusive regimes are observed (as expected in the liquid\nstate). However, in contrast to neutral counterpart, the overall relaxation\ntime of the polydisperse IL system increases (and hence decreasing diffusion\ncoefficient) with increasing $\\delta$.",
        "positive": "Multiple temperatures and melting of a colloidal active crystal: Thermal fluctuations constantly and evenly excite all vibrational modes in an\nequilibrium crystal. As the temperature rises, these fluctuations promote the\nformation of defects and eventually melting. In active solids, the\nself-propulsion of \"atomic\" units provides another source of strong\nnon-equilibrium fluctuations whose effect on the melting scenario is still\nlargely unexplored. Here we show that when a colloidal crystal is activated by\na bath of swimming bacteria, solvent temperature and active temperature\ncooperate to define dynamic and thermodynamic properties. Our system consists\nof repulsive paramagnetic particles confined in two dimensions and immersed in\na bath of light-driven E. coli. The relative balance between fluctuations and\ninteractions can be adjusted in two ways: by changing the strength of the\nmagnetic field and by tuning activity with light. When the persistence time of\nactive fluctuations is short, a single effective temperature controls both the\namplitudes of vibrational modes and the melting transition. For more persistent\nactive noise, energy equipartition is broken and multiple temperatures emerge,\nwhereas melting occurs before the Lindemann parameter reaches its equilibrium\ncritical value. We show that this phenomenology is fully confirmed by numerical\nsimulations and can be framed within a minimal model of a single active\nparticle in a periodic potential."
    },
    {
        "anchor": "Analytic study of clustering in shaken granular material using\n  zero-range processes: We show that models used to described granular clustering due to vertical\nshaking belong to the class of zero-range processes. This correspondence allows\nus to derive exactly in a very easy and straightforward manner a number of\nproperties of the models like particle distribution functions, phase diagram,\nand characteristic time of clusterization.",
        "positive": "Brownian motion of flexibly-linked colloidal rings: Ring, or cyclic, polymers have unique properties compared to linear polymers,\ndue to their topologically closed structure that has no beginning or end.\nExperimental measurements on molecular ring polymers are challenging due to\ntheir polydispersity in molecular weight and the presence of undesired side\nproducts such as chains. Here, we study an experimental model system for cyclic\npolymers, that consists of rings of flexibly-linked micron-sized colloids with\n$n$=4..8 segments. We characterize the conformations of these flexible\ncolloidal rings and find that they are freely-jointed up to steric\nrestrictions. We measure their diffusive behavior and compare it to\nhydrodynamic simulations. Interestingly, flexible colloidal rings have a larger\ntranslational and rotational diffusion coefficient compared to colloidal\nchains. In contrast to chains, their internal deformation mode shows slower\nfluctuations for $n\\lesssim 8$ and saturates for higher values of $n$. We show\nthat constraints stemming from the ring structure cause this decrease in\nflexibility for small $n$ and infer the expected scaling of the flexibility as\nfunction of ring size. Our findings could have implications for the behavior of\nboth synthetic and biological ring polymers, as well as for the dynamic modes\nof floppy colloidal materials."
    },
    {
        "anchor": "Contact model for elastically anisotropic bodies and efficient\n  implementation into the discrete-element method: We introduce a contact law for the normal force generated between two\ncontacting, elastically anisotropic bodies of arbitrary geometry. The only\nrequirement is that their surfaces be smooth and frictionless. This anisotropic\ncontact law is obtained from a simplification of the exact solution to the\ncontinuum elasticity problem and takes the familiar form of Hertz' contact law,\nwith the only difference being the orientation-dependence of the\nmaterial-specific contact modulus. The contact law is remarkably accurate when\ncompared with the exact solution, for a wide range of materials and surface\ngeometries. We describe a computationally efficient implementation of the\ncontact law into a discrete element method code, taking advantage of the\nprecomputation of the contact modulus over all possible orientations. Finally,\nwe showcase two application examples based on real materials where elastic\nanisotropy of the particles induces noticeable effects on macroscopic behavior.\nNotably, the second example demonstrates the ability to engineer tunable\nvibrational band gaps in a one-dimensional granular crystal by mere rotation of\nthe constituent spherical particles.",
        "positive": "Smectic ordering in athermal systems of rod-like triblock copolymers: The phase behavior of the system of parallel rigid triblock copolymers is\nexamined using the second-virial density functional theory. The triblock\nparticle consists of two identical infinitely thin hard rods of finite lengths\non the opposite ends of one central hard cylinder with nonzero length and\ndiameter. Stability analyses and free energy calculations show that the system\nof parallel particles can form not only uniform nematic and smectic A phases,\nbut a smectic-C phase too. The stability and structure of the tilted structure\nis controlled by only the diameter and the length of the central cylinder\nsegment. Interestingly, the diameter effects only the layer tilting and the\nperiodicity, but not the packing fraction of the nematic to smectic-C\ntransition. For all values of cylinder length the usual smectic-A and smectic-C\ntransitions compete with each other and no nematic-columnar transition is\nobserved. At low and high cylinder length the smectic-A phase is stabilized\nfirst, while the smectic C is the most stable for intermediate length values."
    },
    {
        "anchor": "From transient fluidization processes to Herschel-Bulkley behavior in\n  simple yield stress fluids: Stress-induced fluidization of a simple yield stress fluid, namely a carbopol\nmicrogel, is addressed through extensive rheological measurements coupled to\nsimultaneous temporally and spatially resolved velocimetry. These combined\nmeasurements allow us to rule out any bulk fracture-like scenario during the\nfluidization process such as that suggested in [Caton {\\it et al., Rheol Acta},\n2008, {\\bf 47}, 601-607]. On the contrary, we observe that the transient regime\nfrom solidlike to liquidlike behaviour under a constant shear stress $\\sigma$\nsuccessively involves creep deformation, total wall slip, and shear banding\nbefore a homogeneous steady state is reached. Interestingly, the total duration\n$\\tau_f$ of this fluidization process scales as $\\tau_f \\propto 1/(\\sigma -\n\\sigma_c)^{\\beta}$, where $\\sigma_c$ stands for the yield stress of the\nmicrogel, and $\\beta$ is an exponent which only depends on the microgel\nproperties and not on the gap width or on the boundary conditions. Together\nwith recent experiments under imposed shear rate [Divoux {\\it et al., Phys.\nRev. Lett.}, 2010, {\\bf 104}, 208301], this scaling law suggests a route to\nrationalize the phenomenological Herschel-Bulkley (HB) power-law classically\nused to describe the steady-state rheology of simple yield stress fluids. In\nparticular, we show that the {\\it steady-state} HB exponent appears as the\nratio of the two fluidization exponents extracted separately from the {\\it\ntransient} fluidization processes respectively under controlled shear rate and\nunder controlled shear stress.",
        "positive": "Anomalous distribution functions in sheared suspensions: We investigate velocity probability distribution functions (PDF) of sheared\nhard-sphere suspensions. As observed in our Stokes flow simulations and\nexplained by our single-particle theory, these PDFs can show pronounced\ndeviations from a Maxwell-Boltzmann distribution. The PDFs are symmetric around\nzero velocity and show a Gaussian core and exponential tails over more than six\norders of magnitude of probability. Following the excellent agreement of our\ntheory and simulation data, we demonstrate that the distribution functions\nscale with the shear rate, the particle volume concentration, as well as the\nfluid viscosity."
    },
    {
        "anchor": "Emergence of rigidity at the structural glass transition: a first\n  principle computation: We compute the shear modulus of structural glasses from a first principle\napproach based on the cloned liquid theory. We find that the intra-state\nshear-modulus, which corresponds to the plateau modulus measured in linear\nvisco-elastic measurements, strongly depends on temperature and vanishes\ncontinuously when the temperature is increased beyond the glass temperature.",
        "positive": "Granular Solid Hydrodynamics (GSH): a broad-ranged macroscopic theory of\n  granular media: A unified continuum-mechanical theory has been until now lacking for granular\nmedia, some believe it could not exist. Derived employing the hydrodynamic\napproach, GSH is such a theory, though as yet a qualitative one. The behavior\nbeing accounted for includes static stress distribution, elastic wave,\nelasto-plastic motion, the critical state and rapid dense flow. The equations\nand application to a few typical experiments are presented here."
    },
    {
        "anchor": "Community detection forecasts material failure in a sheared granular\n  material: The stability of a granular material is a collective phenomenon controlled by\nindividual particles through their interactions. Forecasting when granular\nmaterials will undergo an abrupt failure is an ongoing challenge due to the\nintricate interactions between particles. Here, we report experiments on\nphotoelastic disks undergoing intermittent stick-slip dynamics in a quasi-2D\nannular shear apparatus, with the evolving network of contact forces made\nvisible via polarized light. We characterize the system by interpreting the\ninterparticle forces as a multilayer network, and apply GenLouvin community\ndetection to identify strongly correlated groups of particles. We observe that\nthe community structure becomes increasingly volatile as the material\napproaches failure, and that this volatility provides a forecast that precedes\nwhat is detectable by considering the forces alone. We additionally observe\nthat both weak and strong forces contribute to the strength of this forecast.\nThese findings provide a new approach to detect patterns of causality and\nforecast impending failures.",
        "positive": "Effect of the strength of attraction between nanoparticles on Wormlike\n  micelle-nanoparticle system: The nanoparticle-Equilibrium polymer (or Wormlike micellar) system shows\nmorphological changes from percolating network-like structures to\nnon-percolating clusters with a change in the minimum approaching distance\n(EVP-excluded volume parameter) between nanoparticles and the matrix of\nequilibrium polymers. The shape anisotropy of nanoparticle clusters can be\ncontrolled by changing the polymer density. In this paper, the synergistic\nself-assembly of nanoparticles inside equilibrium polymeric matrix (or Wormlike\nmicellar matrix) is investigated with respect to the change in the strength of\nattractive interaction between nanoparticles. A shift in the point of\nmorphological transformation of the system to lower values of EVP as a result\nof a decrease in the strength of the attractive nanoparticle interaction is\nreported. We show that the absence of the attractive interaction between\nnanoparticles leads to the low packing of nanoparticle structures, but does not\nchange the morphological behaviour of the system. We also report the formation\nof the system spanning sheet-like arrangement of nanoparticles which are\narranged in alternate layers of matrix polymers and nanoparticles."
    },
    {
        "anchor": "Shear and Compression Viscoelasticity in Polymer Monolayers: Poly-vinlyacetate (PVAc) forms very stable and reproducible monolayers on the\nsurface of water, a model system to understand polymer physics on two\ndimensions. A recently introduced technique is applied here to to study\nviscoelasticity of PVAc monolayers. The method is based on measurement of\nsurface tension in two orthogonal directions during anisotropic deformation.\nCompression and shear moduli are explored over a very large concentration\nrange, highlighting a series of four different regimes. At low concentration\nthe polymers are in a dilute gas. Above the overlap concentration $\\Gamma^\\ast$\nthere is a fluid semi-dilute region, where the monolayer properties are\ndescribed by scaling laws. At a threshold concentration $\\Gamma^{\\ast\\ast}$, a\ndecrease in the gradient of pressure with concentration is observed, and we\nargue that there is still a large fraction of free area on the surface.\nCompressing further, we then identify close packing as the point where the\npressure gradient rises sharply and a shear modulus emerges. This is\ninterpreted as a transition to a soft-solid due to the kinetic arrest of\nclose-packed monomers. The reological properties of PVAc above\n$\\Gamma^{\\ast\\ast}$ have not been studied previously. Discussion includes\npossible explanations for the observed behaviour in terms of both equilibrium\nand non-equilibrium conditions, and the relation to microscopic chain\nproperties. Temperature dependent effects around $\\Gamma^{\\ast\\ast}$ are also\nobserved and described.",
        "positive": "Micellization in the presence of polyelectrolyte: We present a simple model to study micellization of amphiphiles condensed on\na rodlike polyion. Although the mean field theory leads to a first order\nmicellization transition for sufficiently strong hydrophobic interactions, the\nsimulations show that no such thermodynamic phase transition exists. Instead,\nthe correlations between the condensed amphiphiles can result in a structure\nformation very similar to micelles."
    },
    {
        "anchor": "Sonoluminescing Gas Bubbles: We draw attention to the fact that the popular but unproven hypothesis of\nshock-driven sonoluminescence is incompatible with the reported synchronicity\nof the single bubble sonoluminescence (SBSL) phenomenon. Moreover, it is not a\nnecessary requirement, since we show that the sub-shock dynamic heating in gas\nbubble cavitation can lead to conditions required to generate intense 100ps\nlight pulses. To wit we study the dynamics of the interior of a cavitating gas\nbubble subject to conditions suitable for sonoluminescence. We explore\nquantitatively the transfer of energy from the sound wave to the bubble\ninterior, the frequency of atomic collisions in the bubble, the limits of\nquasi-stability of the non-linear bubble oscillations driven by an acoustical\nfield, and obtain the implied reaction time scales.",
        "positive": "Geometric frustration induces the transition between rotation and\n  counterrotation in swirled granular media: Granular material in a swirled container exhibits a curious transition as the\nnumber of particles is increased: at low densities the particle cluster rotates\nin the same direction as the swirling motion of the container, while at high\ndensities it rotates in the opposite direction. We investigate this phenomenon\nexperimentally and numerically using a co-rotating reference frame in which the\nsystem reaches a statistical steady-state. In this steady-state the particles\nform a cluster whose translational degrees of freedom are stationary, while the\nindividual particles constantly circulate around the cluster's center of mass,\nsimilar to a ball rolling along the wall within a rotating drum. We show that\nthe transition to counterrotation is friction-dependent. At high particle\ndensities, frictional effects result in geometric frustration which prevents\nparticles from cooperatively rolling and spinning. Consequently, the particle\ncluster rolls like a rigid body with no-slip conditions on the container wall,\nwhich necessarily counterrotates around its own axis. Numerical simulations\nverify that both wall-disc friction and disc-disc friction are critical for\ninducing counterrotation."
    },
    {
        "anchor": "Rate-dependent Stick-slips in Steady Shearing: Signature of Transition\n  between Granular Solid and Fluid: Despite extensive studies on either smooth granular-fluid flow or the\nsolid-like deformation at the slow limit, the change between these two extremes\nremains largely unexplored. By systematically investigating the fluctuations of\ntightly packed grains under steady shearing, we identify a transition zone with\nprominent stick-slip avalanches. We establish a state diagram, and propose a\nnew dimensionless shear rate based on the speed dependence of inter-particle\nfriction and particle size. With fluid-immersed particles confined in a fixed\nvolume and forced to \"flow\" at viscous numbers $J$ decades below reported\nvalues, we answer how a granular system can transition to the regime sustained\nby solid-to-solid friction that goes beyond existing paradigms based on\nsuspension rheology.",
        "positive": "A Macromolecule in a Solvent: Adaptive Resolution Molecular Dynamics\n  Simulation: We report adaptive resolution molecular dynamics simulations of a flexible\nlinear polymer in solution. The solvent, i.e., a liquid of tetrahedral\nmolecules, is represented within a certain radius from the polymer's center of\nmass with a high level of detail, while a lower coarse-grained resolution is\nused for the more distant solvent. The high resolution sphere moves with the\npolymer and freely exchanges molecules with the low resolution region through a\ntransition regime. The solvent molecules change their resolution and number of\ndegrees of freedom on-the-fly. We show that our approach correctly reproduces\nthe static and dynamic properties of the polymer chain and surrounding solvent."
    },
    {
        "anchor": "Period tripling causes rotating spirals in agitated wet granular layers: Pattern formation of a thin layer of vertically agitated wet granular matter\nis investigated experimentally. Rotating spirals with three arms, which\ncorrespond to the kinks between regions with different colliding phases, are\nthe dominating pattern. This preferred number of arms corresponds to period\ntripling of the agitated granular layer, unlike predominantly subharmonic\nFaraday crispations in dry granular matter. The chirality of the spatiotemporal\npattern corresponds to the rotation direction of the spirals.",
        "positive": "Supervised learning in a mechanical system: Mechanical metamaterials are usually designed to show desired responses to\nprescribed forces. In some applications, the desired force-response\nrelationship might be hard to specify exactly, although examples of forces and\ncorresponding desired responses are easily available. Here we propose a\nframework for supervised learning in a thin creased sheet that learns the\ndesired force-response behavior from training examples of spatial force\npatterns and can then respond correctly to previously unseen test forces.\nDuring training, we fold the sheet using different training forces and assume a\nlearning rule that changes stiffness of creases in response to their folding\nstrain. We find that this learning process reshapes non-linearities inherent in\nfolding a sheet so as to show the correct response for previously unseen test\nforces. We study the relationship between training error, test error and sheet\nsize which plays the role of model complexity. Our framework shows how the\ncomplex energy landscape of disordered mechanical materials can be reshaped\nusing an iterative local learning rule."
    },
    {
        "anchor": "On Pastewka & Robbins' criterion for macroscopic adhesion of rough\n  surfaces: Pastewka & Robbins (PNAS, 111(9), 3298-3303, 2014) recently have proposed a\ncriterion to distinguish when two surfaces will stick together or not, and\nsuggested it shows a large conflict with asperity theories. It is found that\ntheir criterion corresponds very closely to the Fuller and Tabor asperity model\none when bandwidth {\\alpha} is small, but otherwise involves a rms ampliture of\nroughness reduced by a factor Sqrt({\\alpha}). Therefore, it implies the\nstickiness of any rough surface is the same as that of the surface where\npractically all wavelength components of roughness are removed except the very\nfine ones, which is perhaps counterintuitive. The results are therefore very\ninteresting, if confirmed. Possible sources of approximations are indicated,\nand a significant error is found in plotting the pull-off data which may\nimprove the fit with Fuller and Tabor. However, still they show finite pull-off\nvalues in cases where both their own criterion and an asperity based one seem\nto suggest non stickiness, and the results are in these respects inconclusive.",
        "positive": "The origin of stiffening in cross-linked semiflexible networks: Strain stiffening of protein networks is explored by means of a finite strain\nanalysis of a two-dimensional network model of cross-linked semiflexible\nfilaments. The results show that stiffening is caused by non-affine network\nrearrangements that govern a transition from a bending dominated response at\nsmall strains to a stretching dominated response at large strains.\nThermally-induced filament undulations only have a minor effect; they merely\npostpone the transition."
    },
    {
        "anchor": "Fluid squeeze-out between solids with rough surfaces: We study the fluid squeeze-out from the interface between an elastic solid\nwith a flat surface and a rigid solid with a randomly rough surface. As an\napplication we discuss fluid squeeze-out between a tire tread block and a road\nsurface. Some implications for the leakage of seals are discussed, and\nexperimental data are presented to test the theory.",
        "positive": "Ice Rule Breakdown and frustrated antiferrotoroidicity in an artificial\n  colloidal Cairo ice: We combine experiments and numerical simulations to investigate the low\nenergy states and the emergence of topological defects in an artificial\ncolloidal ice in the Cairo geometry. This type of geometry is characterized by\na mixed coordination ($z$), with coexistence of both $z=3$ and $z=4$ vertices.\nWe realize this particle ice by confining field tunable paramagnetic colloidal\nparticles within a lattice of topographic double wells at a one to one filling\nusing optical tweezers. By raising the interaction strength via an applied\nmagnetic field, we find that the ice rule breaks down, and positive monopoles\nwith charge $q=+2$ accumulate in the $z = 4$ vertices and are screened by\nnegative ones ($q=-1$) in the $z = 3$. The resulting, strongly coupled state\nremains disordered. Further, via analysis of the mean chirality associated to\neach pentagonal plaquette, we find that the disordered ensemble for this\ngeometry is massively degenerate and it corresponds to a frustrated\nantiferrotoroid."
    },
    {
        "anchor": "Liquid migration in sheared unsaturated granular media: We show how liquid migrates in sheared unsaturated granular media using a\ngrain scale model for capillary bridges. Liquid is redistributed to neighboring\ncontacts after rupture of individual capillary bridges leading to\nredistribution of liquid on large scales. The liquid profile evolution\ncoincides with a recently developed continuum description for liquid migration\nin shear bands. The velocity profiles which are linked to the migration of\nliquid as well as the density profiles of wet and dry granular media are\nstudied.",
        "positive": "Perfluorooctanoic acid rigidifies a model lipid membrane: We report a combined dynamic light scattering and neutron spin-echo (NSE)\nstudy on vesicles composed of the phospholipid\n1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine under the influence of varying\namounts of perfluorooctanoic acid. We study local lipid bilayer undulations\nusing NSE on time scales up to 200 ns. Similar to the effect evoked by\ncholesterol, we attribute the observed lipid bilayer stiffening to a condensing\neffect of the perfluorinated compound on the membrane."
    },
    {
        "anchor": "Modeling Fluid Polyamorphism Through a Maximum-Valence Approach: We suggest a simple model to describe polyamorphism in single-component\nfluids using a maximum-valence approach. The model contains three types of\ninteractions: i) atoms attract each other by van der Waals forces that generate\na liquid-gas transition at low pressures, ii) atoms may form covalent bonds\nthat induce association, and iii) bonded atoms attract or repel each other\nstronger than non-bonded atoms, thus generating liquid-liquid separation. As an\nexample, we qualitatively compare this model with the behavior of liquid sulfur\nand show that condition (iii) generates a liquid-liquid phase transition in\naddition to the liquid-gas phase transition.",
        "positive": "Armouring of a frictional interface by mechanical noise: A dry frictional interface loaded in shear often displays stick-slip. The\namplitude of this cycle depends on the probability that a slip event nucleates\ninto a rupture, and on the rate at which slip events are triggered. This rate\nis determined by the distribution $P(x)$ of soft spots which yields if the\nshear stress is increased by some amount $x$. In minimal models of a frictional\ninterface that include disorder, inertia and long-range elasticity, we\ndiscovered an 'armouring' mechanism, by which the interface is greatly\nstabilised after a large slip event: $P(x)$ then vanishes at small arguments,\nas $P(x)\\sim x^\\theta$ [1]. The exponent $\\theta>0$, which exists only in the\npresence of inertia (otherwise $\\theta=0$), was found to depend on the\nstatistics of the disorder in the model, a phenomenon that was not explained.\nHere, we show that a single-particle toy model with inertia and disorder\ncaptures the existence of a non-trivial exponent $\\theta>0$, which we can\nanalytically relate to the statistics of the disorder."
    },
    {
        "anchor": "Shear thickening in densely packed suspensions of spheres and rods\n  confined to few layers: We investigate confined shear thickening suspensions for which the sample\nthickness is comparable to the particle dimensions. Rheometry measurements are\npresented for densely packed suspensions of spheres and rods with aspect ratios\n6 and 9. By varying the suspension thickness in the direction of the shear\ngradient at constant shear rate, we find pronounced oscillations in the stress.\nThese oscillations become stronger as the gap size is decreased, and the stress\nis minimized when the sample thickness becomes commensurate with an integer\nnumber of particle layers. Despite this confinement-induced effect, viscosity\ncurves show shear thickening that retains bulk behavior down to samples as thin\nas two particle diameters for spheres, below which the suspension is jammed.\nRods exhibit similar behavior commensurate with the particle width, but they\nshow additional effects when the thickness is reduced below about a particle\nlength as they are forced to align; the stress increases for decreasing gap\nsize at fixed shear rate while the shear thickening regime gradually\ntransitions to a Newtonian scaling regime. This weakening of shear thickening\nas an ordered configuration is approached contrasts with the strengthening of\nshear thickening when the packing fraction is increased in the disordered bulk\nlimit, despite the fact that both types of confinement eventually lead to\njamming.",
        "positive": "Stability and Orientation of Lamellae in Diblock Copolymer Films: The dynamics of microphase separation and the orientation of lamellae in\ndiblock copolymers is investigated in terms of a mean-field model. The\nformation of lamellar structures and their stable states are explored and it is\nshown that lamellae are stable not only for the period of the structure\ncorresponding to the minimum of the free energy. The range of wavelengths of\nstable lamellae is determined by a functional approach, introduced with this\nwork, which is in agreement with the results of a linear stability analysis.\nThe effects of the interaction of block copolymers with confining plane\nboundaries on the lamellae orientation are studied by an extensive analysis of\nthe free energy. By changing the surface property at one boundary, a transition\nfrom a preferentially perpendicular to a parallel lamellar orientation with\nrespect to the boundaries is found, which is rather independent of the distance\nbetween the boundaries. Computer simulations reveal, that the time scale of the\nlamellar orientational order dynamics, which is quantitatively characterized in\nterms of an orientational order parameter and the structure factor, depends\nsignificantly on the properties of the confining boundaries as well as on the\nquench depth."
    },
    {
        "anchor": "Connecting local active forces to macroscopic stress in elastic media: In contrast with ordinary materials, living matter drives its own motion by\ngenerating active, out-of-equilibrium internal stresses. These stresses\ntypically originate from localized active elements embedded in an elastic\nmedium, such as molecular motors inside the cell or contractile cells in a\ntissue. While many large-scale phenomenological theories of such active media\nhave been developed, a systematic understanding of the emergence of stress from\nthe local force-generating elements is lacking. In this paper, we present a\nrigorous theoretical framework to study this relationship. We show that the\nmedium's macroscopic active stress tensor is equal to the active elements'\nforce dipole tensor per unit volume in both continuum and discrete linear\nhomogeneous media of arbitrary geometries. This relationship is conserved on\naverage in the presence of disorder, but can be violated in nonlinear elastic\nmedia. Such effects can lead to either a reinforcement or an attenuation of the\nactive stresses, giving us a glimpse of the ways in which nature might harness\nmicroscopic forces to create active materials.",
        "positive": "Direction dependency of extraordinary refraction index in uniaxial\n  nematic liquid crystals: The article presents a straightforward experiment that directly and\nillustratively demonstrates double refraction. For this purpose, two liquid\ncrystalline cells were designed, which enable qualitative and quantitative\nmeasurements of the extraordinary refractive index direction dependency in a\nuniaxial nematic liquid crystal."
    },
    {
        "anchor": "Statics and dynamics of inhomogeneous liquids via the internal-energy\n  functional: We give a variational formulation of classical statistical mechanics where\nthe one-body density and the local entropy distribution constitute the trial\nfields. Using Levy's constrained search method it is shown that the grand\npotential is a functional of both distributions, that it is minimal in\nequilibrium, and that the minimizing fields are those at equilibrium. The\nfunctional splits into a sum of entropic, external energetic and internal\nenergetic contributions. Several common approximate Helmholtz free energy\ndensity functionals, such as the Rosenfeld fundamental measure theory for hard\nsphere mixtures, are transformed to internal energy functionals. The\nvariational derivatives of the internal energy functional are used to\ngeneralize dynamical density functional theory to include the dynamics of the\nmicroscopic entropy distribution, as is relevant for studying heat transport\nand thermal diffusion.",
        "positive": "Enhanced Activity Reduces the Duration of Intermittent L\u00e9vy Walks in\n  Bacterial Turbulence: Dense bacterial suspensions display collective motion exhibiting coherent\nflow structures reminiscent of turbulent flows. In contrast to inertial\nturbulence, understanding the microscopic dynamics of bacterial fluid elements\nundergoing collective motion is in its incipient stages. Here, we report\nexperiments revealing correlations between the microscopic dynamics and the\nemergence of collective motion in bacterial suspensions. Our detailed analysis\nof the passive tracers and the velocity field of the bacterial suspensions\nallowed us to systematically correlate the Lagrangian and the Eulerian\nperspectives. Bacteria within the collective dynamics revealed initial\nballistic dynamics followed by intermittent L\\'evy walk before the eventual\ndecay to random Gaussian fluctuations. Intriguingly, the persistence length and\ntime of the fluid motion decrease with an increase in the activity, which, in\nturn, reduces the duration of L\\'evy walk. Our results reveal transitions in\nmicroscopic dynamics underlying the bacterial turbulence and their control via\nthe intrinsic time scales set by the effective activity of the flow."
    },
    {
        "anchor": "Relaxation to steady states of a binary liquid mixture around an\n  optically heated colloid: We study the relaxation dynamics of a binary liquid mixture near a\nlight-absorbing Janus particle after switching on and off illumination using\nexperiments and theoretical models. The dynamics is controlled by the\ntemperature gradient formed around the heated particle. Our results show that\nthe relaxation is asymmetric: the approach to a nonequilibrium steady state is\nmuch slower than the return to thermal equilibrium. Approaching a\nnonequilibrium steady state is a two-step process leading to the behavior of\nthe spatial variance of concentration field similar to the initial overshoot in\nresponse to an external field found in diverse soft materials. The initial\ngrowth of concentration fluctuations after switching on illumination follows a\npower law in agreement with the hydrodynamic and purely diffusive model. The\nenergy out-flow from the system after switching off illumination is well\ndescribed by a stretched exponential function of time with characteristic time\nproportional to the ratio of the energy stored in the steady state to the total\nenergy flux in this state.",
        "positive": "Effect of shear force on the separation of double stranded DNA: Using the Langevin Dynamics simulation, we have studied the effects of the\nshear force on the rupture of short double stranded DNA at different\ntemperatures. We show that the rupture force increases linearly with the chain\nlength and approaches to the asymptotic value in accordance with the\nexperiment. The qualitative nature of these curves almost remains same for\ndifferent temperatures but with a shift in the force. We observe three\ndifferent regimes in the extension of covalent bonds (back bone) under the\nshear force."
    },
    {
        "anchor": "Percolation in suspensions of hard nanoparticles: From spheres to\n  needles: We investigate geometric percolation and scaling relations in suspensions of\nnanorods, covering the entire range of aspect ratios from spheres to extremely\nslender needles. A new version of connectedness percolation theory is\nintroduced and tested against specialized Monte Carlo simulations. The theory\naccurately predicts percolation thresholds for aspect ratios as low as 10. The\npercolation threshold for rod-like particles of aspect ratios below 1000\ndeviates significantly from the inverse aspect ratio scaling prediction,\nthought to be valid in the limit of infinitely slender rods and often used as a\nrule of thumb for nano-fibers in composite materials. Hence, most fibers that\nare currently used as fillers in composite materials cannot be regarded as\npractically infinitely slender for the purposes of percolation theory.\nComparing percolation thresholds of hard rods and new benchmark results for\nideal rods, we find that (i) for large aspect ratios, they differ by a factor\nthat is inversely proportional to the connectivity distance between the hard\ncores, and (ii) they approach the slender rod limit differently.",
        "positive": "Dynamical effects of long-range interaction revealed in screened Coulomb\n  interacting ring systems: Understanding the intriguing physical effects of long-range interactions is a\ncommon theme in a host of physical systems. In this work, based on the\nclassical screened Coulomb interacting ring model, we investigate the dynamical\neffects of the long-range interaction from the unique perspective of analyzing\nthe dynamical response of the system to disturbance. We reveal the featured\ndynamics brought by the long-range interaction, including the efficient\ntransformation of the disturbance into the uniform global rotation of the\nsystem, the suppression of the intrinsic noise, and the fast relaxation of\nparticle speed."
    },
    {
        "anchor": "Ageing under stress and mechanical fragility of soft solids of laponite: In this work, we investigate the ageing behavior of soft glassy solids of\naqueous suspension of laponite under shear flow. We observe that when an\nimposed time is normalized by a dominating relaxation time of the system, the\nrheological response at different ages shows superposition. Analysis of this\nbehavior suggests that the structural evolution with age under a deformation\nfield, as represented by the dependence of dominant relaxation mode on age,\nbecomes weaker as the system becomes progressively less homogeneous due to\nenhanced attractive interactions caused by addition of salt. Creep-recovery\nbehavior at same elastic modulus shows more viscous dissipation for a system\nhaving more salt, demonstrating increase in the mechanical fragility. This\nstudy shows that an increase in the concentration of salt, which enhances\nattractive interactions and causes greater inhomogeneity, leads to a state\nwherein the particles are held together by weaker interactions. This work leads\nto important insights into how microstructure affects the ageing dynamics. We\ndiscuss the observed behavior in the context of ageing in colloidal glasses and\ngels of aqueous suspension of laponite.",
        "positive": "Fluctations and noise in time-resolved light scattering experiments :\n  measuring temporally heterogeneous dynamics: We use Time Resolved Correlation (TRC), a recently introduced light\nscattering method, to study the dynamics of a variety of jammed, or glassy,\nsoft materials. The output of a TRC experiment is cI(t,tau), the time series of\nthe degree of correlation between the speckle patterns generated by the light\nscattered at time t and t+tau. We characterize the fluctuations of cI by\ncalculating their Probability Density Function, their variance as a function of\nthe lag tau, and their time autocorrelation function. The comparison between\nthese quantities for a Brownian sample and for jammed materials indicate\nunambiguously that the slow dynamics measured in soft glasses is temporally\nheterogeneous. The analogies with recent experimental, numerical and\ntheoretical work on temporal heterogeneity in the glassy dynamics are briefly\ndiscussed."
    },
    {
        "anchor": "When Do Like Charges Attract?: We study the interaction potential between two polyions inside a colloidal\nsuspension. It is shown that at large separation the interaction potential is\npurely repulsive, with the induced attractive interactions being doubly\nscreened. For short separations the condensed counterions become correlated,\nwhat leads to an effective attraction between the two macromolecules.",
        "positive": "Viscoelastic scaling regimes for marginally-rigid fractal spring\n  networks: A family of marginally-rigid (isostatic) spring networks with fractal\nstructure up to a controllable length was devised and the viscoelastic spectra\n$G^{*}(\\omega)$ calculated. Two non-trivial scaling regimes were observed,\n(i)~$G^{\\prime}\\approx G^{\\prime\\prime}\\propto\\omega^{\\Delta}$ at low\nfrequencies, consistent with $\\Delta=1/2$; (ii)~$G^{\\prime}\\propto\nG^{\\prime\\prime}\\propto\\omega^{\\Delta^{\\prime}}$ for intermediate frequencies\ncorresponding to fractal structure, consistent with a theoretical prediction\n$\\Delta^{\\prime}=(\\ln3-\\ln2)/(\\ln3+\\ln2)$. The cross-over between these two\nregimes occurred at lower frequencies for larger fractals in a manner\nsuggesting diffusive-like dispersion. Solid gels generated by introducing\ninternal stresses exhibited similar behaviour above a low-frequency cut-off,\nindicating the relevance of these findings to real-world applications."
    },
    {
        "anchor": "Force spectroscopy of polymer desorption: Theory and Molecular Dynamics\n  simulation: Forced detachment of a single polymer chain, strongly-adsorbed on a solid\nsubstrate, is investigated by two complementary methods: a coarse-grained\nanalytical dynamical model, based on the Onsager stochastic equation, and\nMolecular Dynamics (MD) simulations with Langevin thermostat. The suggested\napproach makes it possible to go beyond the limitations of the conventional\nBell-Evans model. We observe a series of characteristic force spikes when the\npulling force is measured against the cantilever displacement during detachment\nat constant velocity $v_c$ (displacement control mode) and find that the\naverage magnitude of this force increases as $v_c$ grows. The probability\ndistributions of the pulling force and the end-monomer distance from the\nsurface at the moment of final detachment are investigated for different\nadsorption energy $\\epsilon$ and pulling velocity $v_c$. Our extensive\nMD-simulations validate and support the main theoretical findings. Moreover,\nthe simulation reveals a novel behavior: for a strong-friction and massive\ncantilever the force spikes pattern is smeared out at large $v_c$. As a\nchallenging task for experimental bio-polymers sequencing in future we suggest\nthe fabrication of stiff, super-light, nanometer-sized AFM probe.",
        "positive": "Geometrical frustration yields fiber formation in self-assembly: Controlling the self-assembly of supramolecular structures is vital for\nliving cells, and a central challenge for engineering at the nano- and\nmicroscales. Nevertheless, even particles without optimized shapes can robustly\nform well-defined morphologies. This is the case in numerous medical conditions\nwhere normally soluble proteins aggregate into fibers. Beyond the diversity of\nmolecular mechanisms involved, we propose that fibers generically arise from\nthe aggregation of irregular particles with short-range interactions. Using a\nminimal model of ill-fitting, sticky particles, we demonstrate robust fiber\nformation for a variety of particle shapes and aggregation conditions.\nGeometrical frustration plays a crucial role in this process, and accounts for\nthe range of parameters in which fibers form as well as for their metastable\ncharacter."
    },
    {
        "anchor": "Hierarchical deep reinforcement learning controlled three-dimensional\n  navigation of microrobots in blood vessels: Designing intelligent microrobots that can autonomously navigate and perform\ninstructed routines in blood vessels, a complex and crowded environment with\nobstacles including dense cells, different flow patterns and diverse vascular\ngeometries, can offer enormous possibilities in biomedical applications. Here\nwe report a hierarchical control scheme that enables a microrobot to\nefficiently navigate and execute customizable routines in blood vessels. The\ncontrol scheme consists of two highly decoupled components: a high-level\ncontroller setting short-ranged dynamic targets to guide the microrobot to\nfollow a preset path and a low-level deep reinforcement learning (DRL)\ncontroller responsible for maneuvering microrobots towards these dynamic\nguiding targets. The proposed DRL controller utilizes three-dimensional (3D)\nconvolutional neural networks and is capable of learning control policy\ndirectly from a coarse raw 3D sensory input. In blood vessels with rich\nconfigurations of red blood cells and vessel geometry, the control scheme\nenables efficient navigation and faithful execution of instructed routines. The\ncontrol scheme is also robust to adversarial perturbations including blood\nflows. This study provides a proof-of-principle for designing data-driven\ncontrol systems for autonomous navigation in vascular networks; it illustrates\nthe great potential of artificial intelligence for broad biomedical\napplications such as target drug delivery, blood clots clear, precision\nsurgery, disease diagnosis, and more.",
        "positive": "Phase diagrams of binary mixtures of patchy colloids with distinct\n  numbers of patches: The network fluid regime: We calculate the network fluid regime and phase diagrams of binary mixtures\nof patchy colloids, using Wertheim's first order perturbation theory and a\ngeneralization of Flory-Stockmayer's theory of polymerization. The colloids are\nmodelled as hard spheres with the same diameter and surface patches of the same\ntype, $A$. The only difference between species is the number of their patches\n-or functionality-, $f_A^{(1)}$ and $f_A^{(2)}$ (with $f_A^{(2)}>f_A^{(1)}$).\nWe have found that the difference in functionality is the key factor\ncontrolling the behaviour of the mixture in the network (percolated) fluid\nregime. In particular, when $f_A^{(2)}\\ge2f_A^{(1)}$ the entropy of bonding\ndrives the phase separation of two network fluids which is absent in other\nmixtures. This changes drastically the critical properties of the system and\ndrives a change in the topology of the phase diagram (from type I to type V)\nwhen $f_A^{(1)}>2$. The difference in functionality also determines the\nmiscibility at high (osmotic) pressures. If $f_A^{(2)}-f_A^{(1)}=1$ the mixture\nis completely miscible at high pressures, while closed miscibility gaps at\npressures above the highest critical pressure of the pure fluids are present if\n$f_A^{(2)}-f_A^{(1)}>1$. We argue that this phase behaviour is driven by a\ncompetition between the entropy of mixing and the entropy of bonding, as the\nlatter dominates in the network fluid regime."
    },
    {
        "anchor": "Designing stimulus-sensitive colloidal walkers: Colloidal particles with DNA `legs' that can bind reversibly to receptors on\na surface can be made to `walk' if there is a gradient in receptor\nconcentration. We use a combination of theory and Monte Carlo simulations to\nexplore how controllable parameters, e.g. coating density and binding strength,\naffect the dynamics of such colloids. We find that competition between\nthermodynamic and kinetic trends imply that there is an optimal value for both,\nthe binding strength and the number of `legs' for which transport is fastest.\nUsing available thermodynamic data on DNA binding, we indicate how\ndirectionally reversible, temperature-controlled transport of colloidal walkers\ncan be achieved. In particular, the present results should make it possible to\ndesign a chromatographic technique that can be used to separate colloids with\ndifferent DNA functionalization.",
        "positive": "Entropic identification of the first order freezing transition of a\n  suspension of hard sphere particles: We analyse the experimental particle current auto correlation function (CAF)\nof suspensions of hard spheres. Interactions between the particles are mediated\nby thermally activated acoustic excitations in the solvent. Those acoustic\nmodes are tantamount to the system's (energy) microstates and by their\northogonality, each of those modes can be identified with an independent\nBrownian particle current. Accordingly, partitioning of the system's energy\nstates is impressed on the CAF. This impression provides a novel measure of the\nentropy and location of a partitioning/entropy limit at a packing fraction that\ncoincides with that of the observed suspension's first order freezing\ntransition."
    },
    {
        "anchor": "Elastic Theory of Defects in Toroidal Crystals: We report a comprehensive analysis of the ground state properties of\naxisymmetric toroidal crystals based on the elastic theory of defects on curved\nsubstrates. The ground state is analyzed as a function of the aspect ratio of\nthe torus, which provides a non-local measure of the underlying Gaussian\ncurvature, and the ratio of the defect core-energy to the Young modulus.\nSeveral structural features are discussed,including a spectacular example of\ncurvature-driven amorphization in the limit of the aspect ratio approaching\none. The outcome of the elastic theory is then compared with the results of a\nnumerical study of a system of point-like particles constrained on the surface\nof a torus and interacting via a short range potential.",
        "positive": "Conformation-dependent sequence design of polymer chains in melts: Conformation-dependent design of polymer sequences can be considered as a\ntool to control macromolecular self-assembly. We consider the monomer unit\nsequences created via the modification of polymers in a homogeneous melt in\naccordance with the spatial positions of the monomer units. The geometrical\npatterns of lamellae, hexagonally packed cylinders, and balls arranged in a\nbody-centered cubic lattice are considered as typical microphase-separated\nmorphologies of block copolymers. Random trajectories of polymer chains are\ndescribed by the diffusion-type equations and, in parallel, simulated in the\ncomputer modeling. The probability distributions of block length $k$, which are\nanalogous to the first-passage probabilities, are calculated analytically and\ndetermined from the computer simulations. In any domain, the probability\ndistribution can be described by the asymptote $~k^{-3/2}$ at moderate values\nof $k$ if the spatial size of the block is less than the smallest\ncharacteristic size of the domain. For large blocks, the exponential asymptote\n$exp(-const \\, k a^2/d_{as}^2)$ is valid, $d_{as}$ being the asymptotic domain\nlength (a is the monomer unit size). The number average block lengths and their\ndispersities change linearly with the block length for lamellae, cylinders, and\nballs, when the domain is characterized by a single characteristic size. If the\ndomain is described by more than one size, the number average block length can\ngrow nonlinearly with the domain sizes and the length das can depend on all of\nthem."
    },
    {
        "anchor": "Dynamical analysis of an optical rocking ratchet: Theory and experiment: A thorough analysis of the dynamics in a deterministic optical rocking\nratchet (introduced in A. V. Arzola et al., Phys. Rev. Lett. 106, 168104\n(2011)) and a comparison with experimental results are presented. The studied\nsystem consists of a microscopic particle interacting with a periodic and\nasymmetric light pattern, which is driven away from equilibrium by means of an\nunbiased time- periodic external force. It is shown that the asymmetry of the\neffective optical potential depends on the relative size of the particle with\nrespect to the spatial period, and this is analyzed as an effective mechanism\nfor particle fractionation. The necessary conditions to obtain current\nreversals in the deterministic regime are discussed in detail.",
        "positive": "Rheology of Lamellar Liquid Crystals in Two and Three Dimensions: A\n  Simulation Study: We present large scale computer simulations of the nonlinear bulk rheology of\nlamellar phases (smectic liquid crystals) at moderate to large values of the\nshear rate (Peclet numbers 10-100), in both two and three dimensions. In two\ndimensions we find that modest shear rates align the system and stabilise an\nalmost regular lamellar phase, but high shear rates induce the nucleation and\nproliferation of defects, which in steady state is balanced by the annihilation\nof defects of opposite sign. The critical shear rate at onset of this second\nregime is controlled by thermodynamic and kinetic parameters; we offer a\nscaling analysis that relates the critical shear rate to a critical \"capillary\nnumber\" involving those variables. Within the defect proliferation regime, the\ndefects may be partially annealed by slowly decreasing the applied shear rate;\nthis causes marked memory effects, and history-dependent rheology. Simulations\nin three dimensions show instead shear-induced ordering even at the highest\nshear rates studied here. This suggests that the critical shear rate shifts\nmarkedly upward on increasing dimensionality. This may in part reflect the\nreduced constraints on defect motion, allowing them to find and annihilate each\nother more easily. Residual edge defects in the 3D aligned state mostly point\nalong the flow velocity, an orientation impossible in two dimensions."
    },
    {
        "anchor": "Critical Casimir forces in colloidal suspensions on chemically patterned\n  surfaces: We investigate the behavior of colloidal particles immersed in a binary\nliquid mixture of water and 2,6-lutidine in the presence of a chemically\npatterned substrate. Close to the critical point of the mixture, the particles\nare subjected to critical Casimir interactions with force components normal and\nparallel to the surface. Because the strength and sign of these interactions\ncan be tuned by variations in the surface properties and the mixtures\ntemperature, critical Casimir forces allow the formation of highly ordered\nmonolayers but also extend the use of colloids as model systems.",
        "positive": "Amorphous Systems in Athermal, Quasistatic Shear: We present results on a series of 2D atomistic computer simulations of\namorphous systems subjected to simple shear in the athermal, quasistatic limit.\nThe athermal quasistatic trajectories are shown to separate into smooth,\nreversible elastic branches which are intermittently broken by discrete\ncatastrophic plastic events. The onset of a typical plastic event is studied\nwith precision, and it is shown that the mode of the system which is\nresponsible for the loss of stability has structure in real space which is\nconsistent with a quadrupolar source acting on an elastic matrix. The plastic\nevents themselves are shown to be composed of localized shear transformations\nwhich organize into lines of slip which span the length of the simulation cell,\nand a mechanism for the organization is discussed. Although within a single\nevent there are strong spatial correlations in the deformation, we find little\ncorrelation from one event to the next, and these transient lines of slip are\nnot to be confounded with the persistent regions of localized shear --\nso-called \"shear bands\" -- found in related studies. The slip lines gives rise\nto particular scalings with system length of various measures of event size.\nStrikingly, data obtained using three differing interaction potentials can be\nbrought into quantitative agreement after a simple rescaling, emphasizing the\ninsensitivity of the emergent plastic behavior in these disordered systems to\nthe precise details of the underlying interactions. The results should be\nrelevant to understanding plastic deformation in systems such as metallic\nglasses well below their glass temperature, soft glassy systems (such as dense\nemulsions), or compressed granular materials."
    },
    {
        "anchor": "Investigation of the structure and thermodynamics of star-polymers in\n  semi-dilute solution: In this work, we consider a semi-dilute solution of identical star-polymers,\nmade of attached flexible long polymer chains of the same polymerization degree\nN. We first compute the effective pair-potential between star-polymers. Such a\npotential results from the excluded volume forces between monomers. We show\nthat this potential is logarithmic, below some known characteristic distance,\n&#963;, depending on the number of attached chains per star-polymer, f, and\nvolume fraction of polymers, &#966;0 . Beyond &#963;, the potential fails\nexponentially. Second, we investigate the structure and thermodynamics of these\nstar-polymers. To this end, we use the integral equation method with the\nhybridized-mean spherical approximation. The numerical resolution of this\nequation gives the structure factor of the star-polymers, for various particle\ndensities. Finally, the standard relationships between thermodynamics and\nstructure enable us to deduce three physical quantities, namely the isotherm\ncompressibility, pressure and internal energy, as functions of density.",
        "positive": "On creation and evolution of dark solitons in Bose-Einstein condensates: Generation of dark solitons from large initial excitations and their\nevolution in a quasi-one-dimensional Bose-Einstein condensate trapped by a\nharmonic potential is studied analytically and numerically. In the case of a\nsingle deep soliton main characteristics of its motion such as a frequency and\namplitude of oscillations are calculated by means of the perturbation theory\nwhich in the leading order results in a Newtonian dynamics, corrections to\nwhich are computed as well. It is shown that long-time dynamics of a dark\nsoliton in a generic situation deviates substantially from outcomes of the\nnaive application of the Ehrenfest theorem. We also consider three different\ntechniques of controllable creation of multi-soliton structures (soliton\ntrains) from large initial excitations and calculate their initial parameters\n(depths and velocities) with the use of a generalized Bohr-Sommerfeld\nquantization rule. Multi-soliton effects are discussed."
    },
    {
        "anchor": "Size-dependent contact angle, and wetting and drying transition of a\n  droplet adsorbed on to a spherical substrate: Line tension effect: The size-dependent contact angle and the drying and wetting morphological\ntransition are studied with respect to the volume change for a spherical\ncap-shaped droplet placed on a spherical substrate. The line-tension effect is\nincluded using the rigorous formula for the Helmholtz free energy in the\ndroplet capillary model. A morphological drying transition from a cap-shaped to\na spherical droplet occurs when the substrate is hydrophobic and the droplet\nvolume is small, similar to the transition predicted on a flat substrate. In\naddition, a morphological wetting transition from a cap-shaped to a wrapped\nspherical droplet occurs for a hydrophilic substrate and a large droplet\nvolume. The contact angle depends on the droplet size: it decreases as the\ndroplet volume increases when the line tension is positive, whereas it\nincreases when the line tension is negative. The spherical droplets and wrapped\ndroplets are stable when the line tension is positive and large.",
        "positive": "Rheology of active polar emulsions: from linear to unidirectional and\n  unviscid flow, and intermittent viscosity: The rheological behaviour of an emulsion made of an active polar component\nand an isotropic passive fluid is studied by lattice Boltzmann methods.\nDifferent flow regimes are found by varying the values of shear rate and\nextensile activity (occurring, e.g., in microtubule-motor suspensions). By\nincreasing activity, a first transition occurs from linear flow regime to\nspontaneous persistent unidirectional macro-scale flow, followed by another\ntransition either to (low shear) intermittent flow regime with coexistence of\nstates with positive, negative, and vanishing apparent viscosity, or to (high\nshear) symmetric shear thinning regime. The different behaviours can be\nexplained in terms of the dynamics of the polarization field close to the\nwalls. A maximum entropy production principle selects the most likely states in\nthe intermittent regime."
    },
    {
        "anchor": "Electrical Conductivity in Magnesium-Doped Al_2 O_3 Crystal at Moderate\n  Temperatures: AC and DC electrical measurements between 273 and 800 K were used to\ncharacterize the electrical conductivity of Al_2 O_3:Mg single crystals\ncontaining [Mg]^{0} center. At low fields contacts are blocking. At high\nfields, electrical current flows steadily through the sample and the I-V\ncharacteristic corresponds to a directly biased barrier whit a series\nresistance (bulk resistance). AC measurements yield values for the junction\ncapacitance as well as for the sample resistance, and provide perfectly\nreproducible conductivity values. The conductivity varies linearly whit the\n[Mg]^{0} concentration and a thermal activation energy of 0.68 eV was obtained,\nwhich agrees very well with the activation energy previously reported for\nmotion of free holes.",
        "positive": "Heat capacity of liquids: an approach from the solid phase: We calculate the energy and heat capacity of a liquid on the basis of its\nelastic properties and vibrational states. The experimental decrease of liquid\nheat capacity with temperature is attributed to the increasing loss of two\ntransverse modes with frequency $\\omega<1/\\tau$, where $\\tau$ is liquid\nrelaxation time. In a simple model, liquid heat capacity is related to\nviscosity and is compared with the experimental data of mercury. We also\ncalculate the vibrational energy of a quantum liquid, and show that transverse\nphonons can not be excited in the low-temperature limit. Finally, we discuss\nthe implications of the proposed approach to liquids for the problem of glass\ntransition."
    },
    {
        "anchor": "Pressure Correction in Classical Density Functional Theory: Hyper Netted\n  Chain and Hard Sphere Bridge Functionals: Low accuracy of the Solvation Free Energy (SFE) calculation is a known\nproblem of the numerical methods of the Integral Equation Theory of Liquids and\nthe Classical Density Functional Theory (Classical DFT). Although functionals\nwith empirical corrections can essentially improve the predictability of the\nmethods, their universality is still a question. In our recent paper we\nconnected the SFE calculation errors with the incorrect pressure in the\nClassical DFT and proposed the a posteriory correction to improve the results\n(J. Phys. Chem. Lett., 5, 1925-1942 ). This paper raised a discussion in the\ncommunity. In particular, recently appeared a critical reply where pointed some\nthermodynamical inconsistencies of the derivations in our paper (J. Chem.\nTheory Comput., 11, 378-380). In the present work we re-derive the pressure\ncorrection in a more simple way and show that despite the inaccuracies during\nthe derivation, the final form of the previously derived correction is correct.\nWe also test the applicability of the proposed correction to the functionals\nwhich include a three- and many- body terms from the fundamental measure theory\n(FMT) for hard sphere fluid. We test all the functionals on a set of model\nsystems and discuss the obtained results.",
        "positive": "Short Cyclic Structures in Polymer Model Networks: A Test of Mean Field\n  Approximation by Monte Carlo Simulations: A mean field rate theory description of the homo- and co-polymerization of\n$f$-functional molecules is developed, which contains the formation of short\ncyclic structures inside the network. The predictions of this model are\ncompared with Monte-Carlo simulations of cross-linking of star polymers in\nsolution. We find that homo-polymerizations are well captured by mean-field\nmodels at concentrations larger than one quarter of the geometrical overlap\nconcentration. All simulation data can be fit using a single geometric\nparameter for cyclization. The simulation data reveal that within the range of\nparameters of the present study correlations among multiply connected molecules\ncan be neglected. Thus, mean-field treatments of homopolymerizations are\nreasonable approximations, if short cycles are properly addressed.\nCo-polymerization is considered in the case of strict A-B reactions, where all\nreactive groups of individual molecules are either of type A or B. For these\nsystems we find a clear influence of the local intermixing of A and B groups\nfor all concentrations investigated. In consequence, mean-field models are less\nappropriate to describe the simulation data. The lack of ring structures\ncontaining an odd number of molecules as compared to homopolymerizations at the\nsame extent of reaction allows for the formation of stable AB networks at\nconcentrations one order of magnitude below the geometrical overlap\nconcentration."
    },
    {
        "anchor": "Deformation Dynamics of Nanopores upon Water Imbibition: Capillarity-driven transport in nanoporous solids is ubiquitous in nature and\nis of increasing importance for the functionality of modern liquid-infused\nengineering materials. During imbibition, highly curved menisci are driven by\nnegative Laplace pressures of several hundred atmospheres, exerting an enormous\ncontractile load on an increasing portion of the porous matrix. Due to the\nchallenge of simultaneously monitoring imbibition and deformation with high\nspatial resolution, the resulting coupling of solid elasticity to liquid\ncapillarity has remained largely unexplored. Here, we study water imbibition in\nmesoporous silica using optical imaging, gravimetry, and high-resolution\ndilatometry. In contrast to an expected Laplace pressure-induced contraction,\nwe find a square-root-of-time expansion and an additional abrupt length\nincrease when the menisci reach the top surface. The final expansion is absent\nwhen we stop the imbibition front inside the porous medium in a dynamic\nimbibition-evaporation equilibrium, as is typical for water transport and\ntranspiration in plants. These peculiar deformation behaviors are validated by\nsingle-nanopore molecular dynamics simulations and described by a continuum\nmodel that highlights the importance of expansive surface stresses at the pore\nwalls (Bangham effect) and the buildup or release of contractile Laplace\npressures as nanoscale menisci collectively advance, arrest, or disappear. Our\nmodel predicts that these observations are valid not only for water imbibition\nin silica, but for any imbibition process in nanopores, regardless of the\nliquid/solid combination. This also suggests that simple deformation\nmeasurements can be used to quantify surface stresses and Laplace pressures or\ntransport in a wide variety of natural and artificial porous media.",
        "positive": "Friction and friction heat of micronscale iron: The paper investigates friction and friction heat of the micronscale iron\nunder influences of velocity of the slider and temperature of the substrate by\nusing smoothed particle hydrodynamics simulations. In the velocity range of 10\n- 100 m/s, change of friction coefficient via velocity well complies with\nexponent or hyperbolic tangent form and friction coefficient begins to approach\na stable value of 0.3 at around a velocity of 50 m/s after a rapidly increasing\nsituation. Friction coefficient steady maintains over the temperature range of\n200 - 400 K at each velocity of 10, 50 or 100 m/s. Friction heat is detailed\nanalyzed via sliding time. Change of temperature of the system via sliding time\nwell complies with sigmoidal functions, an exception of that of the particle\nlayer directly causing friction. The layer causing friction has the highest\nsteady temperature and its temperature rise is the largest one. The temperature\nrise is found to be dependent on increment of the initial temperatures of the\nsubstrate and the slider while the incnt does not efect on configration of the\nslid time - temperature curve"
    },
    {
        "anchor": "Surface creasing of soft elastic continua as a Kosterlitz-Thouless\n  transition: Harnessing a model from composite materials science, we show how point-like\ncusped surface features arise as quasi-particle excitations, termed \"ghost\nfibers\", on the surface of a homogeneous soft elastic material. These\ndeformations appear above a critical compressive strain at which ghost fiber\ndipoles unbind, analogous to vortices in the Kosterlitz-Thouless transition.\nFinite-length creases can be described in the same framework. Our predictions\nfor crease surface profiles and onset strain agree with previous experiments\nand simulations, and further experimental tests are proposed.",
        "positive": "Microscale locomotion in a nematic liquid crystal: Microorganisms often encounter anisotropy, for example in mucus and biofilms.\nWe study how anisotropy and elasticity of the ambient fluid affects the speed\nof a swimming microorganism with a prescribed stroke. Motivated by recent\nexperiments on swimming bacteria in anisotropic environments, we extend a\nclassical model for swimming microorganisms, the Taylor swimming sheet,\nactuated either by transverse or longitudinal traveling waves in a\nthree-dimensional nematic liquid crystal without twist. We calculate the\nswimming speed and entrained volumetric flux as a function of the swimmer's\nstroke properties as well as the elastic and rheological properties of the\nliquid crystal. The behavior is quantitatively and qualitatively\nwell-approximated by a hexatic liquid crystal except in the cases of small\nEricksen number and in a nematic fluid with tumbling parameter near the\ntransition to a flow-aligning nematic, where anisotropic effects dominate. We\nalso propose a novel method of swimming or pumping in a nematic fluid by\npassing a traveling wave of director oscillation along a rigid wall."
    },
    {
        "anchor": "Theories of Binary Fluid Mixtures: From Phase-Separation Kinetics to\n  Active Emulsions: Binary fluid mixtures are examples of complex fluids whose microstructure and\nflow are strongly coupled. For pairs of simple fluids, the microstructure\nconsists of droplets or bicontinuous demixed domains and the physics is\ncontrolled by the interfaces between these domains. At continuum level, the\nstructure is defined by a composition field whose gradients which are steep\nnear interfaces drive its diffusive current. These gradients also cause\nthermodynamic stresses which can drive fluid flow. Fluid flow in turn advects\nthe composition field, while thermal noise creates additional random fluxes\nthat allow the system to explore its configuration space and move towards the\nBoltzmann distribution. This article introduces continuum models of binary\nfluids, first covering some well-studied areas such as the thermodynamics and\nkinetics of phase separation, and emulsion stability. We then address cases\nwhere one of the fluid components has anisotropic structure at mesoscopic\nscales creating nematic (or polar) liquid-crystalline order; this can be\ndescribed through an additional tensor (or vector) order parameter field. We\nconclude by outlining a thriving area of current research, namely active\nemulsions, in which one of the binary components consists of living or\nsynthetic material that is continuously converting chemical energy into\nmechanical work.",
        "positive": "Self-Consistent Field Theory of Multiply-Branched Block Copolymer Melts: We present a numerical algorithm to evaluate the self-consistent field theory\nfor melts composed of block copolymers with multiply-branched architecture. We\npresent results for the case of branched copolymers with doubly-functional\ngroups for multiple branching generations. We discuss the stability of the\ncubic phase of spherical micelles, the A15 phase, as a consequence of tendency\nof the AB interfaces to conform to the polyhedral environment of the Voronoi\ncell of the micelle lattice."
    },
    {
        "anchor": "Dynamic capillary assembly of colloids at interfaces with 10,000g\n  accelerations: Extreme deformation of soft matter is central to our understanding of the\neffects of shock, fracture, and phase change in a variety of systems. Yet,\ndespite, the increasing interest in this area, far-from-equilibrium behaviours\nof soft matter remain challenging to probe. Colloidal suspensions are often\nused to visualise emergent behaviours in soft matter, as they offer precise\ncontrol of interparticle interactions, and ease of visualisation by optical\nmicroscopy. However, previous studies have been limited to deformations that\nare orders of magnitude too slow to be representative of extreme deformation.\nHere we use a two-dimensional model system, a monolayer of colloids confined at\na fluid interface, to probe and visualise the evolution of the microstructure\nduring high-rate deformation driven by ultrasound. We observe the emergence of\na transient network of strings, and use discrete particle simulations to show\nthat it is caused by a delicate interplay of dynamic capillarity and\nhydrodynamic interactions between particles oscillating at high-frequency.\nRemarkably, we find evidence of inertial effects in a colloidal system, caused\nby accelerations approaching 10,000g. These results also suggest that extreme\ndeformation of soft matter offers new opportunities for pattern formation and\ndynamic self-assembly.",
        "positive": "Mirror-symmetry protected higher-order topological zero-frequency\n  boundary and corner modes in Maxwell lattices: Maxwell lattices, where the number of degrees of freedom equals the number of\nconstraints, are known to host topologically-protected zero-frequency modes and\nstates of self stress, characterized by a topological index called topological\npolarization. In this letter, we show that in addition to these known\ntopological modes, with the help of a mirror symmetry, the inherent chiral\nsymmetry of Maxwell lattices creates another topological index, the\nmirror-graded winding number (MGWN). This MGWN is a higher order topological\nindex, which gives rise to topological zero modes and states of self stress at\nmirror-invariant domain walls and corners between two systems with different\nMGWNs. We further show that two systems with same topological polarization can\nhave different MGWNs, indicating that these two topological indices are\nfundamentally distinct."
    },
    {
        "anchor": "The Equation of State of a Gaussian Phantom Network with Defined Cross\n  Link Functionality: A phantom network of Gaussian chains far from the point of gelation can be\ndescribed as a gas of interacting particles represented by the cross links. The\ntype of particles varies with the network functionality, whereas the type of\ninteraction depends on the properties of the connecting chains. In a mean field\napproximation the Equation of State can be calculated using Mayer's cluster\nexpansion. The resulting isothermal compressibility is compared for different\ncross link functionalities.",
        "positive": "Effect of Interactions on Molecular Fluxes and Fluctuations in the\n  Transport Across Membrane Channels: Transport of molecules across membrane channels is investigated theoretically\nusing exactly solvable one-dimensional discrete-state stochastic models. An\ninteraction between molecules and membrane pores is modeled via a set of\nbinding sites with different energies. It is shown that the interaction\npotential strongly influences the particle currents as well as fluctuations in\nthe number of translocated molecules. For small concentration gradients the\nattractive sites lead to largest currents and fluctuations, while the repulsive\ninteractions yield the largest fluxes and dispersions for large concentration\ngradients. Interaction energies that lead to maximal currents and maximal\nfluctuations are the same only for locally symmetric potentials, while they\ndiffer for the locally asymmetric potentials. The conditions for the most\noptimal translocation transport with maximal current and minimal dispersion are\ndiscussed. It is argued that in this case the interaction strength is\nindependent of local symmetry of the potential of mean forces. In addition, the\neffect of the global asymmetry of the interaction potential is investigated,\nand it is shown that it also strongly affects the particle translocation\ndynamics. These phenomena can be explained by analyzing the details of the\nparticle entering and leaving the binding sites in the channel."
    },
    {
        "anchor": "Predicting nonlinear physical aging of glasses from equilibrium\n  relaxation via the material time: The noncrystalline glassy state of matter plays a role in virtually all\nfields of materials science and offers complementary properties to those of the\ncrystalline counterpart. The caveat of the glassy state is that it is out of\nequilibrium and therefore exhibits physical aging, i.e., material properties\nchange over time. For half a century, the physical aging of glasses has been\nknown to be described well by the material-time concept, although the existence\nof a material time has never been directly validated. We do this here by\nsuccessfully predicting the aging of the molecular glass\n4-vinyl-1,3-dioxolan-2-one from its linear relaxation behavior. This\nestablishes the defining property of the material time. Via the\nfluctuation-dissipation theorem, our results imply that physical aging can be\npredicted from thermal-equilibrium fluctuation data, which is confirmed by\ncomputer simulations of a binary liquid mixture.",
        "positive": "Charge inversion in colloidal systems: We investigate spherical macroions in the strong Coulomb coupling regime\nwithin the primitive model in salt-free environment. Molecular dynamics (MD)\nsimulations are used to elucidate the effect of $discrete$ macroion charge\ndistribution on charge inversion. A systematic comparison is made with the\ncharge inversion obtained in the conventional continuous charge distribution.\nFurthermore the effect of multivalent counterions is reported."
    },
    {
        "anchor": "Equilibrium States Corresponding to Targeted Hyperuniform Nonequilibrium\n  Pair Statistics: The Zhang-Torquato conjecture [Phys. Rev. E 101, 032124 (2020)] states that\nany realizable pair correlation function $g_2({\\bf r})$ or structure factor\n$S({\\bf k})$ of a translationally invariant nonequilibrium system can be\nattained by an equilibrium ensemble involving only (up to) effective two-body\ninteractions. To test this conjecture, we consider two singular nonequilibrium\nmodels of recent interest that also have the exotic hyperuniformity property: a\n2D \"perfect glass\" and a 3D critical absorbing-state model. We find that each\nnonequilibrium target can be achieved accurately by equilibrium states with\neffective one- and two-body potentials, lending further support to the\nconjecture. To characterize the structural degeneracy of such\nnonequilibrium-equilibrium correspondence, we compute higher-order statistics\nfor both models, as well as those for a hyperuniform 3D uniformly randomized\nlattice (URL), whose higher-order statistics can be very precisely ascertained.\nInterestingly, we find that the differences in the higher-order statistics\nbetween nonequilibrium and equilibrium systems with matching pair statistics,\nas measured by the \"hole\" probability distribution, provides measures of the\ndegree to which a system is out of equilibrium. We show that all three systems\nstudied possess the \\textit{bounded-hole} property, and that holes near the\nmaximum hole size in the URL are much rarer than those in the underlying simple\ncubic lattice. Remarkably, upon quenching, the effective potentials for all\nthree systems possess local energy minima with stronger forms of\nhyperuniformity compared to their target counterparts. Our work is expected to\nfacilitate the self-assembly of tunable hyperuniform soft-matter systems.",
        "positive": "Screw dislocation interaction in smectic-A liquid crystals in an\n  anharmonic approximation: The interaction of two screw dislocations in smectic-A liquid crystals is\ntreated using an anharmonic correction to the elastic energy density. In the\npresent contribution the elastic energy and the force between two screw\ndislocations is evaluated and discussed. For screw dislocations with both\nparallel and opposite Burgers vectors there is an attraction of dislocations\nfor their small separations while for greater separations there is a repulsion.\nIt can be explained by dominating terms in interaction energy which do not\ndepend on signs of dislocations. In this way, the interaction energy of screw\ndislocations in smectic A liquid crystal within an anharmonic approximation\ndiffers with respect to the case of screw dislocations in solids."
    },
    {
        "anchor": "How does the motion of the surrounding molecules depend on the shape of\n  a folding molecular motor ?: Azobenzene based molecules have the property of isomerizing when illuminated.\nIn relation with that photoisomerization property, azobenzene containing\nmaterials are the subject of unexplained massive mass transport. In this work\nwe use an idealised rectangular chromophore model to study the dependence of\nthe isomerization induced transport on the chromophore dimensions. Our results\nshow the presence of a motor arm length threshold for induced transport, which\ncorresponds to the host molecule size. Above the threshold, the diffusive\nmotions increase proportionally to the chromophore length. Intriguingly, we\nfind only a very small chromophore width dependence of the induced diffusive\nmotions. Our very simplified motor reproduces relatively well the behavior\nobserved using the real DR1 motor molecule, suggesting that the complex closing\nprocedure and the detailed shape of the motor are not necessary to induce the\nmolecular motions.",
        "positive": "Self-Organized Criticality: A Guide to Water-Protein Landscape Evolution: We focus here on the scaling properties of small interspecies differences\nbetween red cone opsin transmembrane proteins, using a hydropathic elastic\nroughening tool previously applied to the rhodopsin rod transmembrane proteins.\nThis tool is based on a non-Euclidean hydropathic metric realistically rooted\nin the atomic coordinates of 5526 protein segments, which thereby encapsulates\nuniversal non-Euclidean long-range differential geometrical features of water\nfilms enveloping globular proteins in the Protein Data Bank. Whereas the\nrhodopsin blue rod water films are smoothest in humans, the red cone opsins'\nwater films are optimized in cats and elephants, consistent with protein\nspecies landscapes that evolve differently in different contexts. We also\nanalyze red cone opsins in the chromatophore-containing family of chameleons,\nsnakes, zebrafish and goldfish, where short- and long-range (BLAST and\nhydropathic) aa correlations are found with values as large as 97-99%. We use\nhydropathic amino acid (aa) optimization to estimate the maximum number Nmax of\ncolor shades that the human eye can discriminate, and obtain 10^6 < Nmax <\n10^7, in good agreement with experiment."
    },
    {
        "anchor": "On the existence of helical structures during the collapse of flexible\n  homopolymers: A Wang-Landau study: In this work, we report our results on the phase transition of a flexible\nhomopolymer from a stretched chain to a compact globule. The Wang-landau method\nis used to study the thermodynamic properties of a the chain up to 512\nmonomers. We believe that the peak in the specific heat at low temperature\n$T\\approx 0.05$ for small chain sizes $N<100$ is a clear evidence of the\nexistence of metastable helical structures observed in a previous study.",
        "positive": "Boson peak, elasticity, and glass transition temperature in polymer\n  glasses: Effects of the rigidity of chain bending: The excess low-frequency vibrational spectrum, called boson peak, and\nnon-affine elastic response are the most important particularities of glasses.\nHerein, the vibrational and mechanical properties of polymeric glasses are\nexamined by using coarse-grained molecular dynamics simulations, with\nparticular attention to the effects of the bending rigidity of the polymer\nchains. As the rigidity increases, the system undergoes a glass transition at a\nhigher temperature (under a constant pressure), which decreases the density of\nthe glass phase. The elastic moduli, which are controlled by the decrease of\nthe density and the increase of the rigidity, show a non-monotonic dependence\non the rigidity of the polymer chain that arises from the non-affine component.\nMoreover, a clear boson peak is observed in the vibrational density of states,\nwhich depends on the macroscopic shear modulus $G$. In particular, the boson\npeak frequency is scaled as $\\omega_\\mathrm{BP} \\propto \\sqrt{G}$. These\nresults provide a positive correlation between the boson peak, shear\nelasticity, and the glass transition temperature."
    },
    {
        "anchor": "Structure of the First and Second Neighbor Shells of Water: Quantitative\n  Relation with Translational and Orientational Order: We perform molecular dynamics simulation of water using the TIP5P model to\nquantify structural order in both the first shell (defined by four nearest\nneighbors)and second shell (defined by twelve next-nearest neighbors) of a\ncentral water molecule. We find the anomalous decrease of orientational order\nupon compression occurs in both shells, but the anomalous decrease of\ntranslational order upon compression occurs {\\it mainly in the second shell}.\nThe decreases of translational and orientational orders upon compression\n(\"structural anomaly\") are thus correlated only in the second shell. Our\nfindings quantitatively confirm the qualitative idea that the thermodynamic,\ndynamic and structural anomalies of water are related to changes in the second\nshell upon compression.",
        "positive": "Importance of pore length and geometry in the adsorption/desorption\n  process: a molecular simulation study: Discrete potentials can describe properly the liquid vapor boundary that is\nnecessary to model the adsorption of gas molecules in mesoporous systems with\ncomputer simulations. Although there are some works in this subject, the\nsimulations are still highly time - consuming. Here we show that an efficient\nalternative is to use the three - dimensional Ising model, which allows one to\nmodel large systems, with geometries as complex as required that accurately\nrepresent the liquid vapor boundary. In particular, we report molecular\nsimulations of cylindrical pores of two different geometry, using a discrete\npotential. The effect of the length of the pore in the hysteresis loop for a\nfinite pore and infinite one is studied in detail. Lastly, we compare our\npredictions with experimental results and find excellent agreement between the\narea of the hysteresis loop predicted for the finite pore and that found in\nadsorption/desorption experiments."
    },
    {
        "anchor": "Capillary suspensions: Particle networks formed through the capillary\n  force: The addition of small amounts of a secondary fluid to a suspension can,\nthrough the attractive capillary force, lead to particle bridging and network\nformation. The capillary bridging phenomenon can be used to stabilize particle\nsuspensions and precisely tune their rheological properties. This effect can\neven occur when the secondary fluid wets the particles less well than the bulk\nfluid. These materials, so-called capillary suspensions, have been the subject\nof recent research studying the mechanism for network formation, the properties\nof these suspensions, and how the material properties can be modified. Recent\nwork in colloidal clusters is summarized and the relationship to capillary\nsuspensions is discussed. Capillary suspensions can also be used as a pathway\nfor new material design and some of these applications are highlighted. Results\nobtained to date are summarized and central questions that remain to be\nanswered are proposed in this review.",
        "positive": "Solid phase properties and crystallization in simple model systems: We review theoretical and simulational approaches to the description of\nequilibrium bulk crystal and interface properties as well as to the\nnonequilibrium processes of homogeneous and heterogeneous crystal nucleation\nfor the simple model systems of hard spheres and Lennard-Jones particles. For\nthe equilibrium properties of bulk and interfaces, density functional theories\nemploying fundamental measure functionals prove to be a precise and versatile\ntool, as exemplified with a closer analysis of the hard sphere crystalliquid\ninterface. A detailed understanding of the dynamic process of nucleation in\nthese model systems nevertheless still relies on simulational approaches. We\nreview bulk nucleation and nucleation at structured walls and examine in closer\ndetail the influence of walls with variable strength on nucleation in the\nLennard-Jones fluid. We find that a planar crystalline substrate induces the\ngrowth of a crystalline film for a large range of lattice spacings and\ninteraction potentials. Only a strongly incommensurate substrate and a very\nweakly attractive substrate potential lead to crystal growth with a non-zero\ncontact angle."
    },
    {
        "anchor": "Atomic-scale interaction of a crack and an infiltrating fluid: In this work we investigate the Orowan hypothesis, that decreases in surface\nenergy due to surface adsorbates lead directly to lowered fracture toughness,\nat an atomic/molecular level. We employ a Lennard-Jones system with a slit\ncrack and an infiltrating fluid, nominally with gold-water properties, and\nexplore steric effects by varying the soft radius of fluid particles and the\ninfluence of surface energy/hydrophobicity via the solid-fluid binding energy.\nUsing previously developed methods, we employ the J-integral to quantify the\nsensitivity of fracture toughness to the influence of the fluid on the crack\ntip, and exploit dimensionless scaling to discover universal trends in\nbehavior.",
        "positive": "Mean field approach to first and second order phase transitions in ionic\n  liquids: Ionic liquids are solvent-free electrolytes, some of which possess an\nintriguing self-assembly property. Using a mean-field framework (based on\nOnsager's relations) we show that bulk nano-structures arise via type-I and II\nphase transitions (PT), which directly affect the electrical double layer (EDL)\nstructure. Ginzburg-Landau equation is derived and PT are related to\ntemperature, potential and interactions. The type-I PT occurs for geometrically\ndissimilar anion/cation ratio and, surprisingly, is induced by perturbations on\norder of thermal fluctuations. Finally, we compare the insights with the\ndecaying charge layers within the EDL, as widely observed in experiments."
    },
    {
        "anchor": "Monte Carlo Tests of Nucleation Concepts in the Lattice Gas Model: The conventional theory of homogeneous and heterogeneous nucleation in a\nsupersaturated vapor is tested by Monte Carlo simulations of the lattice gas\n(Ising) model with nearest-neighbor attractive interactions on the simple cubic\nlattice. The theory considers the nucleation process as a slow (quasi-static)\ncluster (droplet) growth over a free energy barrier $\\Delta F^*$, constructed\nin terms of a balance of surface and bulk term of a \"critical droplet\" of\nradius $R^*$, implying that the rates of droplet growth and shrinking\nessentially balance each other for droplet radius $R=R^*$. For heterogeneous\nnucleation at surfaces, the barrier is reduced by a factor depending on the\ncontact angle. Using the definition of \"physical\" clusters based on the\nFortuin-Kasteleyn mapping, the time-dependence of the cluster size distribution\nis studied for \"quenching experiments\" in the kinetic Ising model, and the\ncluster size $\\ell ^*$ where the cluster growth rate changes sign is estimated.\nThese studies of nucleation kinetics are compared to studies where the relation\nbetween cluster size and supersaturation is estimated from equilibrium\nsimulations of phase coexistence between droplet and vapor in the canonical\nensemble. The chemical potential is estimated from a lattice version of the\nWidom particle insertion method. For large droplets it is shown that the\n\"physical clusters\" have a volume consistent with the estimates from the lever\nrule. \"Geometrical clusters\" (defined such that each site belonging to the\ncluster is occupied and has at least one occupied neighbor site) yield valid\nresults only for temperatures less than 60% of the critical temperature, where\nthe cluster shape is non-spherical. We show how the chemical potential can be\nused to numerically estimate $\\Delta F^*$ also for non-spherical cluster\nshapes.",
        "positive": "Experimental observations of fractal landscape dynamics in a dense\n  emulsion: Many soft and biological materials display so-called 'soft glassy' dynamics;\ntheir constituents undergo anomalous random motions and complex cooperative\nrearrangements. A recent simulation model of one soft glassy material, a\ncoarsening foam, suggested that the random motions of its bubbles are due to\nthe system configuration moving over a fractal energy landscape in\nhigh-dimensional space. Here we show that the salient geometrical features of\nsuch high-dimensional fractal landscapes can be explored and reliably\nquantified, using empirical trajectory data from many degrees of freedom, in a\nmodel-free manner. For a mayonnaise-like dense emulsion, analysis of the\nobserved trajectories of oil droplets quantitatively reproduces the\nhigh-dimensional fractal geometry of the configuration path and its associated\nenergy minima generated using a computational model. That geometry in turn\ndrives the droplets' complex random motion observed in real space. Our results\nindicate that experimental studies can elucidate whether the similar dynamics\nin different soft and biological materials may also be due to fractal landscape\ndynamics."
    },
    {
        "anchor": "Can we describe charged nanoparticles with electrolyte theories? Insight\n  from mesoscopic simulation techniques: Electrolyte theories enable to describe the structural and dynamical\nproperties of simple electrolytes in solution, such as sodium chloride in\nwater. Using these theories for aqueous solutions of charged nanoparticles is a\nstraightforward route to extract their charge and size from experimental data.\nNevertheless, for such strongly asymmetric electrolytes, the validity of the\nunderlying approximations have never been properly challenged with exact\nsimulation results. In the present work, well established mesoscopic numerical\nsimulations are used to challenge the ability of advanced electrolyte theories\nto predict the electrical conductivity of suspensions of charged nanoparticles,\nin the salt-free case. The theories under investigation are based on the\nDebye-Fuoss-Onsager treatment of electrolyte transport. When the nanoparticles\nare small enough (about one nanometer large), the theoretical results agree\nremarkably well with the simulation ones, even in the high concentration regime\n(packing fraction of in nanoparticles larger than 3$\\%$ ). Strikingly, for\nhighly charged nanoparticles, the theory is able to capture the non-monotonic\nvariation of the ratio of the electrical conductivity to its value at infinite\ndilution (ideal value) as a function of the concentration. However, the tested\ntheories fail to describe the conductivity of suspensions containing larger\nnanoparticles ({\\em e.g.} of diameter $4$~nm). Finally, only small charged\nnanoparticles can be considered as {\\em ions}, as far as electrolyte theories\nare concerned.",
        "positive": "Generalization of the Zabolotskaya equation to all incompressible\n  isotropic elastic solids: We study elastic shear waves of small but finite amplitude, composed of an\nanti-plane shear motion and a general in-plane motion. We use a multiple scales\nexpansion to derive an asymptotic system of coupled nonlinear equations\ndescribing their propagation in all isotropic incompressible non-linear elastic\nsolids, generalizing the scalar Zabolotskaya equation of compressible nonlinear\nelasticity. We show that for a general isotropic incompressible solid, the\ncoupling between anti-plane and in-plane motions cannot be undone and thus\nconclude that linear polarization is impossible for general nonlinear\ntwo-dimensional shear waves. We then use the equations to study the evolution\nof a nonlinear Gaussian beam in a soft solid: we show that a pure (linearly\npolarised) shear beam source generates only odd harmonics, but that introducing\na slight in-plane noise in the source signal leads to a second harmonic, of the\nsame magnitude as the fifth harmonic, a phenomenon recently observed\nexperimentally. Finally, we present examples of some special shear motions with\nlinear polarisation."
    },
    {
        "anchor": "Theoretical and Experimental Adsorption Studies of Polyelectrolytes on\n  an Oppositely Charged Surface: Using self-assembly techniques, x-ray reflectivity measurements, and computer\nsimulations, we study the effective interaction between charged polymer rods\nand surfaces. Long-time Brownian dynamics simulations are used to measure the\neffective adhesion force acting on the rods in a model consisting of a planar\narray of uniformly positively charged, stiff rods and a negatively charged\nplanar substrate in the presence of explicit monovalent counterions and added\nmonovalent salt ions in a continuous, isotropic dielectric medium. This\nelectrostatic model predicts an attractive polymer-surface adhesion force that\nis weakly dependent on the bulk salt concentration and that shows fair\nagreement with a Debye-Huckel approximation for the macroion interaction at\nsalt concentrations near 0.1 M. Complementary x-ray reflectivity experiments on\npoly(diallyldimethyl ammonium) chloride (PDDA) monolayer films on the native\noxide of silicon show that monolayer structure, electron density, and surface\nroughness are likewise independent of the bulk ionic strength of the solution.",
        "positive": "Revealing the microstructure of sodium-montmorillonite aqueous\n  suspensions: Aqueous suspensions of geometrically anisometric (2D) sodium-montmorillonite\n(Na-Mt) particles display a sol-gel transition at very low solids\nconcentrations. The underlying microstructure of the gel has remained a point\nof contention since the time of Irving Langmuir. An in-situ investigation\nencompassing length scales much larger than the individual particles is\nrequired to provide support for one of the two models proposed in the\nliterature: 1) a percolated network governed by electrostatic attraction\nbetween platelets; and 2) a jammed suspension stabilized by repulsive\nelectrostatic forces between particles. We settle this debate by\ncomprehensively probing the microstructure of Na-Mt suspensions using\nultra-small angle neutron/X-ray scattering and found that it is ordered and\ncontains entities that are at least an order of magnitude larger than the\nindividual particles. Complementary cryo-electron microscopy showed both the\npresence of domains having strong particle-particle ordering and regions of\nparticle-particle aggregation. These data indicate 1) the presence of nematic\ndomains, which refutes a purely attractive nature, and 2) assembly of\nparticles, which refutes a purely repulsive nature. Na-Mt gels appear to have a\nhybrid microstructure with both attractive and repulsive domains."
    },
    {
        "anchor": "Delays, Inaccuracies and Anticipation in Microscopic Traffic Models: We generalize a wide class of time-continuous microscopic traffic models to\ninclude essential aspects of driver behaviour not captured by these models.\nSpecifically, we consider (i) finite reaction times, (ii) estimation errors,\n(iii) looking several vehicles ahead (spatial anticipation), and (iv) temporal\nanticipation. The estimation errors are modelled as stochastic Wiener processes\nand lead to time-correlated fluctuations of the acceleration.\n  We show that the destabilizing effects of reaction times and estimation\nerrors can essentially be compensated for by spatial and temporal anticipation,\nthat is, the combination of stabilizing and destabilizing effects results in\nthe same qualitative macroscopic dynamics as that of the respectively\nunderlying simple car-following model. In many cases, this justifies the use of\nsimplified, physics-oriented models with a few parameters only. Although the\nqualitative dynamics is unchanged, multi-anticipation increase both spatial and\ntemporal scales of stop-and-go waves and other complex patterns of congested\ntraffic in agreement with real traffic data. Remarkably, the anticipation\nallows accident-free smooth driving in complex traffic situations even if\nreaction times exceed typical time headways.",
        "positive": "Memory effects in friction: the role of sliding heterogeneities: We report on memory effects involved in the transient frictional response of\na contact interface between a silicone rubber and a spherical glass probe when\nit is perturbed by changes in the orientation of the driving motion or by\nvelocity steps. From measurements of the displacement fields at the interface,\nwe show that observed memory effects can be accounted for by the non-uniform\ndistribution of the sliding velocity within the contact interface. As a\nconsequence of these memory effects, the friction force may no longer be\naligned with respect to the sliding trajectory. In addition, stick-slip motions\nwith a purely geometrical origin are also evidenced. These observations are\nadequately accounted for by a friction model which takes into account\nheterogeneous displacements within the contact area. When a velocity dependence\nof the frictional stress is incorporated in this the model, transient regimes\ninduced by velocity steps are also adequately described. The good agreement\nbetween the model and experiments outlines the role of space heterogeneities in\nmemory effects involved in soft matter friction."
    },
    {
        "anchor": "Contact Topology and the Structure and Dynamics of Cholesterics: Using tools and concepts from contact topology we show that non-vanishing\ntwist implies conservation of the layer structure in cholesteric liquid\ncrystals. This leads to a number of additional topological invariants for\ncholesteric textures, such as layer numbers, that are not captured by\ntraditional descriptions, characterises the nature and size of the chiral\nenergy barriers between metastable configurations, and gives a geometric\ncharacterisation of cholesteric dynamics in any context, including active\nsystems, those in confined geometries or under the influence of an external\nfield.",
        "positive": "Microfluidic device coupled with total internal reflection microscopy\n  for in situ observation of precipitation: In situ observation of precipitation or phase separation induced by solvent\naddition is important in studying its dynamics. Combined with optical and\nfluorescence microscopy, microfluidic devices have been leveraged in studying\nthe phase separation in various materials including biominerals, nanoparticles,\nand inorganic crystals. However, strong scattering from the subphases in the\nmixture is problematic for in situ study of phase separation with high temporal\nand spatial resolution. In this work, we present a quasi-2D microfluidic device\ncombined with total internal reflection microscopy as an approach for in situ\nobservation of phase separation. The quasi-2D microfluidic device comprises of\na shallow main channel and a deep side channel. Mixing between a solution in\nthe main channel (solution A) and another solution (solution B) in the side\nchannel is predominantly driven by diffusion due to high fluid resistance from\nthe shallow height of the main channel, which is confirmed using fluorescence\nmicroscopy. Moreover, relying on diffusive mixing, we can control the\ncomposition of the mixture in the main channel by tuning the composition of\nsolution B. We demonstrate the application of our method for in situ\nobservation of asphaltene precipitation and beta-alanine crystallization."
    },
    {
        "anchor": "Impact-induced hardening in dense frictional suspensions: We numerically study the impact-induced hardening in dense suspensions. We\nemploy the lattice Boltzmann method and perform simulations of dense\nsuspensions under impacts, which incorporate the contact between suspended\nparticles with the free surface of the suspension. Our simulation for a\nfree-falling impactor on a dense suspension reproduces experimental results,\nwhere rebound takes place for frictional particles at high-speed impact and\nhigh volume fraction shortly after the impact before subsequently sinking. We\nfound that the shear stress of the suspension is not affected by the impact,\nwhich clearly distinguishes the impact-induced hardening from the discontinuous\nshear thickening. Instead, we found the existence of a localized region with\ndistinctively high value of normal stress corresponding to the dynamically\njammed region. Our simulation indicates that the frictional interaction between\nsuspended particles is important for the impact-induced hardening to maintain\nthe dynamically jammed region. Furthermore, persistent homology analysis\nsuccessfully elucidates the topological structure of force chains.",
        "positive": "Fractal to Nonfractal Phase Transition in the Dielectric Breakdown Model: A fast method is presented for simulating the dielectric-breakdown model\nusing iterated conformal mappings. Numerical results for the dimension and for\ncorrections to scaling are in good agreement with the recent RG prediction of\nan upper critical $\\eta_c=4$, at which a transition occurs between branching\nfractal clusters and one-dimensional nonfractal clusters."
    },
    {
        "anchor": "Triangular Lattice Model of 2D Defect Melting: We set up a harmonic lattice model for 2D defect melting which, in contrast\nto earlier simple-cubic models, lives on a triangular lattice. Integer-valued\nplastic defect gauge fields allow for the thermal generation of dislocations\nand disclinations. The model produces universal formulas for the melting\ntemperature expressed in terms of the elastic constants, which are different\nfrom those derived for square lattices. They determine a Lindemann-like\nparameter for two-dimensional melting. In contrast to the square crystal which\nunderwent a first-order melting transition, the triangular model melts in two\nsteps. Our results are applied to the melting of Lennard-Jones and electron\nlattices.",
        "positive": "Lower bound on the four-point dynamical susceptibility: Direct\n  experimental test on a granular packing: We track the motion of a horizontally vibrated amorphous assembly of\nbidisperse hard disks, for densities ranging across the jamming transition. We\nderive on very general grounds a bound on the dynamical susceptibility in terms\nof the response of the dynamics to a change in density. This generalizes a\nsimilar bound recently derived for equilibrium liquids. We find that in our\nexperimental system the bound is tight and reproduces the non-monotonic\nbehavior of the dynamical susceptibility both in time and density across the\njamming transition. The underlying scaling behavior reveals an intimate\nconnection between anomalous diffusion and dynamical heterogeneity."
    },
    {
        "anchor": "Connectivity Percolation in Suspensions of Attractive Square-Well\n  Spherocylinders: We have studied the connectivity percolation transition in suspensions of\nattractive square-well spherocylinders by means of Monte Carlo simulation and\nconnectednes percolation theory. In the 1980s the percolation threshold of\nslender fibres has been predicted to scale as the fibres' inverse aspect ratio\n(Phys.~Rev.~B {\\bf 30}, 3933 (1984)). The main finding of our study is that the\nattractive spherocylinder system reaches this inverse scaling regime at much\nlower aspect ratios than found in suspensions of hard spherocylinders. We\nexplain this difference by showing that third virial corrections of the pair\nconnectedness functions, which are responsible for the deviation from the\nscaling regime, are less important for attractive potentials than for hard\nparticles.",
        "positive": "Binding of molecules to DNA and other semiflexible polymers: A theory is presented for the binding of small molecules such as surfactants\nto semiflexible polymers. The persistence length is assumed to be large\ncompared to the monomer size but much smaller than the total chain length. Such\npolymers (e.g. DNA) represent an intermediate case between flexible polymers\nand stiff, rod-like ones, whose association with small molecules was previously\nstudied. The chains are not flexible enough to actively participate in the\nself-assembly, yet their fluctuations induce long-range attractive interactions\nbetween bound molecules. In cases where the binding significantly affects the\nlocal chain stiffness, those interactions lead to a very sharp, cooperative\nassociation. This scenario is of relevance to the association of DNA with\nsurfactants and compact proteins such as RecA. External tension exerted on the\nchain is found to significantly modify the binding by suppressing the\nfluctuation-induced interaction."
    },
    {
        "anchor": "The role of receptor uniformity in multivalent binding: Multivalency is prevalent in various biological systems and applications due\nto the superselectivity that arises from the cooperativity of multivalent\nbinding. Traditionally, it was thought that weaker individual binding would\nimprove the selectivity in multivalent targeting. Here using analytical mean\nfield theory and Monte Carlo simulations, we discover that for receptors that\nare highly uniformly distributed, the highest selectivity occurs at an\nintermediate binding energy and can be significantly greater than the weak\nbinding limit. This is caused by an exponential relationship between the bound\nfraction and receptor concentration, which is influenced by both the strength\nand combinatorial entropy of binding. Our findings not only provide new\nguidelines for the rational design of biosensors using multivalent\nnano-particles but also introduce a new perspective in understanding biological\nprocesses involving multivalency.",
        "positive": "Controlling fracture cascades through twisting and quenching: Fracture limits the structural stability of macroscopic and microscopic\nmaterials, from beams and bones to microtubules and nanotubes. Despite recent\nprogress, fracture control continues to present profound practical and\ntheoretical challenges. A famous longstanding problem posed by Feynman asks why\nbrittle elastic rods appear almost always to fragment into at least three\npieces when placed under large bending stresses. Feynman's observation raises\nfundamental questions about the existence of protocols that can robustly induce\nbinary fracture in brittle materials. Using experiments, simulations and\nanalytical scaling arguments, we demonstrate controlled binary fracture of\nbrittle elastic rods for two distinct protocols based on twisting and\nnonadiabatic quenching. Our experimental data for twist-controlled fracture\nagree quantitatively with a theoretically predicted phase diagram. Furthermore,\nwe establish novel asymptotic scaling relations for quenched fracture. Due to\ntheir general character, these results are expected to apply to torsional and\nkinetic fracture processes in a wide range of systems."
    },
    {
        "anchor": "Ion association in low-polarity solvents: comparisons between theory,\n  simulation, and experiment: The association of ions in electrolyte solutions at very low concentration\nand low temperature is studied using computer simulations and quasi-chemical\nion-pairing theory. The specific case of the restricted primitive model\n(charged hard spheres) is considered. Specialised simulation techniques are\nemployed that lead to efficient sampling of the arrangements and distributions\nof clusters and free ions, even at conditions corresponding to nanomolar\nsolutions of simple salts in solvents with dielectric constants in the range\n5-10, as used in recent experimental work on charged-colloid sus- pensions. A\ndirect comparison is effected between theory and simulation using a variety of\nclustering criteria and theoretical approximations. It is shown that\nconventional distance-based cluster criteria can give erroneous results. A\nreliable set of theoretical and simulation estimators for the degree of\nassociation is proposed. The ion-pairing theory is then compared to\nexperimental results for salt solutions in low-polarity solvents. The agreement\nis excellent, and on this basis some calculations are made for the screening\nlengths which will figure in the treatment of colloid-colloid interactions in\nsuch solutions. The accord with available experimental results is complete.",
        "positive": "Thermal and Athermal Swarms of Self-Propelled Particles: Swarms of self-propelled particles exhibit complex behavior that can arise\nfrom simple models, with large changes in swarm behavior resulting from small\nchanges in model parameters. We investigate the steady-state swarms formed by\nself-propelled Morse particles in three dimensions using molecular dynamics\nsimulations optimized for GPUs. We find a variety of swarms of different\noverall shape assemble spontaneously and that for certain Morse potential\nparameters coexisting structures are observed. We report a rich \"phase diagram\"\nof athermal swarm structures observed across a broad range of interaction\nparameters. Unlike the structures formed in equilibrium self-assembly, we find\nthat the probability of forming a self-propelled swarm can be biased by the\nchoice of initial conditions. We investigate how thermal noise influences swarm\nformation and demonstrate ways it can be exploited to reconfigure one swarm\ninto another. Our findings validate and extend previous observations of\nself-propelled Morse swarms and highlight open questions for predictive\ntheories of nonequilibrium self-assembly."
    },
    {
        "anchor": "Polyelectrolyte-surfactant complex: phases of self-assembled structures: We study the structure of complexes formed between ionic surfactants (SF) and\na single oppositely charged polyelectrolyte (PE) chain. For our computer\nsimulation we use the ``primitive'' electrolyte model: while the\npolyelectrolyte is modeled by a tethered chain of charged hard sphere beads,\nthe surfactant molecules consist of a single charged head bead tethered to a\ntail of tethered hard spheres. A hydrophobic attraction between the tail beads\nis introduced by assuming a Lennard-Jones potential outside the hard-sphere\ndiameter. As a function of the strengths of both the electrostatic and the\nhydrophobic interactions, we find the following scenario: switching on and\nincreasing the electrostatic forces first leads to a stretching of the PE and\nthen by condensation of SF to the formation of a complex. For vanishing\nhydrophobic forces this complex has the architecture of a molecular\nbottle-brush cylindrically centered around the stretched PE molecule. Upon\nincreasing the hydrophobic attraction between the SF tails, a transition occurs\ninverting this structure to a spherical micelle with a neutral core of SF tails\nand a charged corona of SF heads with the PE molecule wrapped around. At\nintermediate hydrophobicity there is a competition between the two structures\nindicated by a non-monotonic dependence of the shape as function of the Coulomb\nstrength, favoring the cylindrical shape for weak and the spherical micellar\ncomplex for strong interaction.",
        "positive": "Schools of skyrmions with electrically tunable elastic interactions: Coexistence of order and fluidity in soft matter often mimics that in\nbiology, allowing for complex dynamics and applications like displays. In\nactive soft matter, emergent order can arise because of such dynamics. Powered\nby local energy conversion, this behavior resembles motions in living systems,\nlike schooling of fish. Similar dynamics at cellular levels drive biological\nprocesses and generate macroscopic work. Inanimate particles capable of such\nemergent behavior could power nanomachines, but most active systems have\nbiological origins. Here we show that thousands-to-millions of topological\nsolitons, dubbed \"skyrmions\", while each converting macroscopically-supplied\nelectric energy, exhibit collective motions along spontaneously-chosen\ndirections uncorrelated with the direction of electric field. Within these\n\"schools\" of skyrmions, we uncover polar ordering, reconfigurable\nmulti-skyrmion clustering and large-scale cohesion mediated by\nout-of-equilibrium elastic interactions. Remarkably, this behavior arises under\nconditions similar to those in liquid crystal displays and may enable dynamic\nmaterials with strong emergent electro-optic responses."
    },
    {
        "anchor": "Predictions of Dynamic Behavior Under Pressure for Two Scenarios to\n  Explain Water Anomalies: Using Monte Carlo simulations and mean field calculations for a cell model of\nwater we find a dynamic crossover in the orientational correlation time $\\tau$\nfrom non-Arrhenius behavior at high temperatures to Arrhenius behavior at low\ntemperatures. This dynamic crossover is independent of whether water at very\nlow temperature is charaterized by a ``liquid-liquid critical point'' or by the\n``singularity free'' scenario. We relate $\\tau$ to fluctuations of hydrogen\nbond network and show that the crossover found for $\\tau$ for both scenarios is\na consequence of the sharp change in the average number of hydrogen bonds at\nthe temperature of the specific heat maximum. We find that the effect of\npressure on the dynamics is strikingly different in the two scenarios, offering\na means to distinguish between them.",
        "positive": "Emergence and Growth Dynamics of Wetting-induced Phase Separation on\n  Soft Solids: Liquid droplets on soft solids, such as soft polymeric gels, can induce\nsubstantial surface deformations, leading to the formation of wetting ridges at\nthe contact points. While these contact ridges have been shown to govern the\nrich surface mechanics of complaint substrates, the inherently divergent\ncharacteristics at contact points and the multiphase nature of soft reticulated\ngels both pose great challenges for continuum mechanical theories in modeling\nsoft wetting phenomena. In this study, we report in-situ experimental\ncharacterizations of the emergence and growth dynamics of the wetting-induced\nphase separation. The measurements demonstrate how the migration of free chains\nprevents the stress singularities at contact points. Based on the Onsager\nvariational principle, we present a phenomenological model that effectively\ncaptures the growth dynamics of this phase separation, including the crossover\nfrom a short-term diffusive state to a long-term equilibrium state. Comparing\nthe model predictions with the experimental results obtained for varied\ncrosslinking densities, we reveal how the intrinsic material parameters of soft\ngels dictate the phase separation dynamics."
    },
    {
        "anchor": "Influence of the liquid film thickness on the coefficient of restitution\n  for wet particles: The normal coefficient of restitution (COR) for a spherical particle bouncing\non a wet plane is investigated experimentally and compared with a model\ncharacterizing the energy loss at impact. For fixed ratios of liquid film\nthickness $\\delta$ to particle diameter $D$, the wet COR is always found to\ndecay linearly with St$^{-1}$, where St, the Stokes number, measures the\nparticle inertia with respect to the viscous force of the liquid. Such a\ndependency suggests a convenient way of predicting the wet COR with two fit\nparameters: A critical COR at infinitely large St and a critical St at zero\nCOR. We characterize the dependency of the two parameters on $\\delta/D$ and\ncompare it with a model considering the energy loss from the inertia and the\nviscosity of the wetting liquid. This investigation suggests an analytical\nprediction of the COR for wet particles.",
        "positive": "The Importance of Reference Frame for Pressure at the Liquid-Vapour\n  Interface: The local pressure tensor is non-unique, a fact which has generated confusion\nand debate in the seventy years since the seminal work by Irving Kirkwood. This\nnon-uniqueness is normally attributed to the interaction path between\nmolecules, especially in the interfacial-science community. In this work we\nreframe this discussion of non-uniqueness in terms of the location, or\nreference frame, used to measure the pressure. By using a general mathematical\ndescription of the liquid-vapour interface, we obtain a reference frame that\nmoves with the interface through time, providing a new insight into the\npressure. We compare this instantaneous moving reference frame with the fixed\nEulerian one. Through this process, we show the requirement that normal\npressure balance at the moving surface is satisfied by surface fluxes, however\nan additional corrective term based on surface curvature is required for the\naverage pressure in a volume. We make the case that a focus on the path of\nintegration is the cause of much of the confusion in the literature. Using an\nexplicit reference frame with a more general derivation of pressure clarifies\nsome of the issues of uniqueness in the pressure tensor and provides a pressure\ntensor which is defined at any instant in time and valid away from\nthermodynamic equilibrium."
    },
    {
        "anchor": "Elucidation of Conformational Hysteresis on a Giant DNA: The conformational behavior of a giant DNA mediated by condensing agents in\nthe bulk solution has been investigated through experimental and theoretical\napproaches. Experimentally, a pronounced conformational hysteresis is observed\nfor folding and unfolding processes, by increasing and decreasing the\nconcentration of condensing agent PEG (Polyethylene glycol), respectively. To\nelucidate the observed hysteresis, a semiflexible chain model is studied by\nusing Monte Carlo simulations for the coil-globule transition. In the\nsimulations, the hysteresis loop emerges for stiff enough chains, indicating\ndistinct pathways for folding and unfolding processes. Also, our results show\nthat globular state is thermodynamically more stable than coiled state in the\nhysteresis loop. Our findings suggest that increasing chain stiffness may\nreduce the chain conformations relevant to the folding pathway, which impedes\nthe folding process.",
        "positive": "Understanding and enhancing the impact-induced tension of a falling\n  chain: When a falling chain strikes a surface, it can accelerate downwards faster\nthan free-fall. This counterintuitive effect occurs when a tension is created\nin the chain above where it strikes the surface. The size of this tension, and\nhow it is produced, depend on the type of chain used. For a chain made of rods\nthat are slightly tilted from horizontal, the impact-induced tension is readily\nobservable. Here are reported experimental observations on such a falling chain\nfor two different situations: when the chain strikes an inclined surface, and\nwhen the chain's mass density decreases with height. It is found that both of\nthese arrangements can increase the downward acceleration. To quantitatively\ndescribe these observations a theoretical model is developed. The model\nsuccessfully predicts the chain's position and velocity, even when the top end\napproaches the surface, without any free parameters. The model also predicts\nthat uniform rods are practically the best for producing large tensions."
    },
    {
        "anchor": "Phase-field modeling of electric field induced poration of lipid\n  membranes: In this work, a model and simulation method to study the dynamics of pore\nformation and annihilation in a lipid membrane under an applied electric field\nhas been developed. A continuum-level diffusive interface model (phase-field)\nmethod is applied to model the evolution of the pore in a lipid membrane patch.\nThe numerical method and results are presented.",
        "positive": "Collective phenomena in granular and atmospheric electrification: In clouds of suspended particles (grains, droplets, spheres, crystals, etc.),\ncollisions electrify the particles and the clouds, producing large electric\npotential differences over large scales. This is seen most spectacularly in the\natmosphere as lighting in thunderstorms, thundersnow, dust storms, and volcanic\nash plumes where multi-million-volt potential differences over scales of\nkilometers can be produced, but it is a general phenomenon in granular systems\nas a whole. The electrification process is not well understood, especially for\nelectrification of insulating particles of the same material. To investigate\nthe relative importances of particle properties (material, size, etc.) and\ncollective phenomena (behaviors of systems at large scales not easily predicted\nfrom local dynamics) in granular and atmospheric electrification, we used a\ntable-top experiment that mechanically shakes particles inside a cell where we\nmeasure the macroscopic electric field between the electrically conducting end\nplates. The measured electric fields are a result of capacitive coupling and\ndirect charge transfer between the particles and the plates. Using a diverse\nrange of mono-material particle sets (plastics, ceramic, glass, and metals), we\nfound that all our particle materials electrify and show similar dynamics with\nlong time-scale temporal variation and an electric field amplitude that depends\non the particle quantity in a complex way. These results suggest that while\nparticle properties do matter like previous investigations have shown,\nmacroscopic electrification of solids is relatively material agnostic and large\nscale collective phenomena play a major role."
    },
    {
        "anchor": "Hydrodynamic interactions of colloidal spheres under shear flow: Particles that are immersed in a fluid exchange momentum via the fluid, hence\ntheir Brownian motion is correlated. By means of multiparticle-collision\ndynamics simulations we study the interactions between two colloidal beads in a\nsheared fluid suspension. Recently, this topic has been addressed in\nexperiments on colloidal particles trapped by optical tweezers in a\nmicrofluidic device [PRL, 103, 230602 (2009)] and theoretically by means of a\nLangevin model [Eur. Phys. J E, 33, 313 (2010)]. Although we neglect the\nrotational degrees of freedom of the colloids, and employ a very simple\ncoupling between the colloids and the flow field, we can reproduce the\nexperimental data and partly explain why it differs from theory.",
        "positive": "Dynamic and rate-dependent yielding in model cohesive suspensions: An experimental system has been found recently, a coagulated CaCO3 suspension\nsystem, which shows very variable yield behaviour depending upon how it is\ntested and, specifically, at what rate it is sheared. At P\\'eclet numbers Pe >\n1 it behaves as a simple Herschel Bulkley liquid, whereas at Pe < 1 highly\nnon-monotonic flow curves are seen. In controlled stress testing it shows\nhysteresis and shear banding and in the usual type of stress scan, used to\nmeasure flow curves in controlled stress mode routinely, it can show very\nerratic and irreproducible behaviour. All of these features will be attributed\nhere to a dependence of the solid phase, or, yield stress, on the prevailing\nrate of shear at the yield point. Stress growth curves obtained from step\nstrain-rate testing showed that this rate-dependence was a consequence of\nP\\'eclet number dependent strain softening. At very low Pe, yield was\ncooperative and the yield strain was order-one, whereas as Pe approached unity,\nthe yield strain reduced to that needed to break interparticle bonds, causing\nthe yield stress to be greatly reduced. It is suspected that rate-dependent\nyield could well be the rule rather than the exception for cohesive suspensions\nmore generally. If so, then the Herschel-Bulkley equation can usefully be\ngeneralized to read (in simple shear). The proposition that rate-dependent\nyield might be general for cohesive suspensions is amenable to critical\nexperimental testing by a range of means and along lines suggested."
    },
    {
        "anchor": "The viscosity-radius relationship from scaling arguments: The viscosity-radius relationship for semi-dilute polymer solutions is\nderived using scaling arguments. The viscosity temperature and the temperature\nradius relationships are combined using the transitive equality relationship.\nThe viscosity-radius relationship is determined to be . The reduced viscosity\nobserved with both increasing temperature and increasing shear rate then\nresults from a reduction in coil radius.",
        "positive": "Shear-induced gelation of self-yielding active networks: Molecular-motor generated active stresses drive the cytoskeleton away from\nequilibrium, endowing it with tunable mechanical properties that are essential\nfor diverse functions such as cell division and motility[1-5]. Designing\nanalogous biomimetic systems is a key prerequisite for creating active matter\nthat can emulate cellular functions[6-7]. These long-term goals requires\nunderstanding of how motor-generated stresses tune the mechanics of filamentous\nnetworks[8-11]. In microtubule-based active matter, kinesin motors generate\nextensile motion that leads to persistent breaking and reforming of the network\nlinks[12]. We study how such microscopic dynamics modifies the network's\nmechanical properties, uncovering that the network viscosity first increases\nwith the imposed shear rate before transitioning back to a low-viscosity state.\nThe non-monotonic shear-dependent viscosity can be controlled by tuning the\nspeed of molecular motors. A two-state phenomenological model that incorporates\nliquid- and solid-like elements quantitatively relates the non-monotonic\nshear-rate-dependent viscosity to locally-measured flows. These studies show\nthat rheology of extensile networks are different from previously studied\nactive gels[13], where contractility enhances mechanical stiffness. Moreover,\nthe flow induced gelation is not captured by continuum models of\nhydrodynamically interacting swimmers[14-21]. Observation of activity-dependent\nviscoelasticity necessitates the development of models for self-yielding of\nsoft active solids whose intrinsic active stresses fluidize or stiffen the\nnetwork."
    },
    {
        "anchor": "Modelling Polymerization-Induced Self Assembly (PISA): In this work we studied polymerization-induced self-assembly by means of\ncomputer simulations. Using this model, phase diagrams of the micelle states\nwere constructed depending on the polymer concentration and the asymmetry of\nthe composition for various reaction conditions. We found that if the reaction\nis ideal controlled radical polymerization (the initiation speed is much larger\nthan the propagation speed and there are no side reactions such as termination\nor chain transfer), the phase diagram is no different from that obtained for\npre-synthesized monodisperse diblock-copolymers with one insoluble block. Next,\nwe studied two cases of slow initiation. We found that the phase diagram change\ndramatically: upon decreasing the initiation speed, the regions of spherical\nand cylindrical micelles shrink, while the region of vesicles/lamellae expands.\nThis happens because at small initiation speed there is a significant amount of\nchains with a very short non-soluble block (and even without such block\naltogether), which do not participate in the formation of micelles. Therefore,\ndecreasing the initiation speed essentially remaps the phase diagram\ncoordinates by making the effective concentration lower (by decreasing the\nnumber of active chains) and the effective block length ratio higher (again,\nbecause the number of active chains gets higher, while the number of monomers\nremains the same).",
        "positive": "Aging near rough and smooth boundaries in colloidal glasses: We use confocal microscopy to study the aging of a bidisperse colloidal glass\nnear rough and smooth boundaries. Near smooth boundaries, the particles form\nlayers, and particle motion is dramatically slower near the boundary as\ncompared to the bulk. Near rough boundaries, the layers nearly vanish, and\nparticle motion is nearly identical to that of the bulk. The gradient in\ndynamics near the boundaries is demonstrated to be a function of the gradient\nin structure for both types of boundaries.Our observations show that\nwall-induced layer structures strongly influence aging."
    },
    {
        "anchor": "Growth and aging in a few phase-separating active matter systems: Via computer simulations we study evolution dynamics in systems of\ncontinuously moving Active Brownian Particles. The obtained results are\ndiscussed against those from the passive 2D Ising case. Following sudden\nquenches of uniform configurations to state points lying within the miscibility\ngaps and to the critical points, we investigate the far-from-steady-state\ndynamics by calculating quantities associated with structure and characteristic\nlength scales. We also study aging for quenches into the miscibility gap and\nprovide a quantitative picture for the scaling behavior of the two-time\norder-parameter correlation function. The overall structure and dynamics are\nconsistent with expectations from the Ising model. This remains true for\ncertain active lattice models as well for which we present results for quenches\nto the critical points.",
        "positive": "Polygons vs. clumps of discs: a numerical study of the influence of\n  grain shape on the mechanical behaviour of granular materials: We performed a series of numerical vertical compression tests on assemblies\nof 2D granular material using a Discrete Element code and studied the results\nwith regard to the grain shape. The samples consist of 5,000 grains made from\neither 3 overlapping discs (clumps - grains with concavities) or six-edged\npolygons (convex grains). These two grain type have similar external envelopes,\nwhich is a function of a geometrical parameter $\\alpha$.\n  In this paper, the numerical procedure applied is briefly presented followed\nby the description of the granular model used. Observations and mechanical\nanalysis of dense and loose granular assemblies under isotropic loading are\nmade. The mechanical response of our numerical granular samples is studied in\nthe framework of the classical vertical compression test with constant lateral\nstress (biaxial test). The comparison of macroscopic responses of dense and\nloose samples with various grain shapes shows that when $\\alpha$ is considered\na concavity parameter, it is therefore a relevant variable for increasing\nmechanical performances of dense samples. When $\\alpha$ is considered an\nenvelope deviation from perfect sphericity, it can control mechanical\nperformances for large strains. Finally, we present some remarks concerning the\nkinematics of the deformed samples: while some polygon samples subjected to a\nvertical compression present large damage zones (any polygon shape), dense\nsamples made of clumps always exhibit thin reflecting shear bands. This paper\nwas written as part of a CEGEO research project www.granuloscience.com"
    },
    {
        "anchor": "Accelerating the calculation of dipolar interactions in particle based\n  simulations with open boundary conditions by means of the P2NFFT method: Magnetic gels are soft elastic materials consisting of magnetic particles\nembedded in a polymer network. Their shape and elasticity can be controlled by\nan external magnetic field, which gives rise to both, engineering and\nbiomedical applications. Computer simulations are a commonly used tool to study\nthese materials. A well-known bottleneck of these simulations is the demanding\ncalculation of dipolar interactions. Under periodic boundary conditions\nestablished algorithms are available for doing this, however, at the expense of\nrestricting the way in which the gels can deform in an external magnetic field.\nMoreover, the magnetic properties depend on the sample shape, ruling out\nperiodic boundary conditions entirely for some research questions. In this\narticle we will employ the recently developed dipolar variant of the P$^2$NFFT\nmethod that is able to calculate dipolar interactions under open boundary\nconditions with an $N \\log N$ scaling in the number of particles, rather than\nthe expensive $N^2$ scaling of a direct summation of pair forces. The dipolar\nP$^2$NFFT method has been implemented within the ScaFaCoS library. The\nmolecular dynamics software ESPResSo has been extended to make use of the\nlibrary.\n  After a short summary of the method, we will discuss its value for studying\nmagnetic soft matter systems. A particular focus is put on developing a tuning\nstrategy to reach the best performance of the method at a predefined accuracy,\nand lastly applying the method to a magnetic gel model. Here, adapting to the\ngel's change in shape during the course of a simulation is of particular\ninterest.",
        "positive": "Surface instabilities generated by a slider pulled across a granular bed: We report an instability of a slider slowly dragged at the surface of a\ngranular bed in a quasistatic regime. The boat-shaped slider sits on the\ngranular medium under its own weight and is free to translate vertically and to\nrotate around the pitch axis while a constant horizontal speed is imposed. For\na wide range of parameters (mass, length, shape, velocity) a regular pattern of\npeaks and troughs spontaneously emerges as the slider travels forward. This\ninstability is studied through experiments using a conveyor belt and by means\nof two-dimensional discrete elements method simulations. We show that the\nwavelength and amplitude of the pattern scale as the length of the slider. We\nalso observe that the ripples disappear for low and high masses, indicating an\noptimal confining pressure. The effect of the shape, more specifically the\ninclination of the front spatula, is studied and found to drastically influence\nboth the wavelength and the amplitude. Finally, we show that the mechanical\ndetails (friction, cohesion) of the contact point between the slider and the\npulling device is critical and remains to be fully understood."
    },
    {
        "anchor": "Dynamic simulations of multicomponent lipid membranes over long length\n  and time scales: We present a stochastic phase-field model for multicomponent lipid bilayers\nthat explicitly accounts for the quasi-two-dimensional hydrodynamic environment\nunique to a thin fluid membrane immersed in aqueous solution. Dynamics over a\nwide range of length scales (from nanometers to microns) for durations up to\nseconds and longer are readily accessed and provide a direct comparison to\nfluorescence microscopy measurements in ternary lipid/cholesterol mixtures.\nSimulations of phase separation kinetics agree with experiment and elucidate\nthe importance of hydrodynamics in the coarsening process.",
        "positive": "Multi-functional Twisted-Kagome lattices: Tuning by Pruning Mechanical\n  Metamaterials: This article investigates phonons and elastic response in randomly diluted\nlattices constructed by combining (via the addition of next-nearest bonds) a\ntwisted kagome lattice, with bulk modulus $B=0$ and shear modulus $G>0$, with\neither a generalized untwisted kagome lattice with $B>0$ and $G>0$ or with a\nhoneycomb lattice with $B>0$ and $G=0$. These lattices exhibit jamming-like\ncritical end-points at which $B$, $G$, or both $B$ and $G$ jump discontinuously\nfrom zero while the remaining moduli (if any) begin to grow continuously from\nzero. Pairs of these jamming points are joined by lines of continuous rigidity\npercolation transitions at which both $B$ and $G$ begin to grow continuously\nfrom zero. The Poisson ratio and $G/B$ can be continuously tuned throughout\ntheir physical range via random dilution in a manner analogous to \"tuning by\npruning\" in random jammed lattices. These lattices can be produced with modern\ntechniques, such as 3D printing, for constructing metamaterials."
    },
    {
        "anchor": "One and two-component hard core plasmas: A field theory is presented for particles which interact via Coulomb and\nhard-core potentials. We apply the method to the one-component plasma (OCP)\nwith hard cores, consisting of identical particles of fixed charge and diameter\nin a neutralizing background, and the symmetric two-component plasma (TCP) with\nhard cores, consisting of equal numbers of positively and negatively charged\nparticles of identical size. We obtain exactly the first few coefficients of a\nsystematic low-density expansion of the free energy for both models. The OCP\ncoefficients go over to the classical Abe result in the high-charge (or small\nhard-core diameter) limit. The TCP, on the other hand, exhibits diverging\ncoefficients in the high-charge limit, which is due to the formation of\nstrongly bound ion-pairs.",
        "positive": "Prediction of the effective force on DNA in a nanopore based on density\n  functional theory: We consider voltage-driving DNA translocation through a nanopore in the\npresent study. By assuming the DNA is coaxial with the cylindrical nanopore, a\nhydrodynamic model for determining effective force on a single DNA molecule in\na nanopore was presented, in which density functional theory (DFT) combined\nwith the continuum Navier-Stokes (NS) equations is utilized to investigate\nelectro-osmotic flow and the viscous drag force acting on the DNA inside a\nnanopore. Surface charge on the walls of the nanopore is also taken into\naccount in our model. The consistence between our calculation and the previous\nexperimental measurement indicates that the present theoretical model is an\neffective tool to predict the hydrodynamic resistance on DNA. Results show that\ncharge inversion, which cannot be obtained by the Poisson-Boltzmann (PB) model,\nwill reduce electro-osmotic velocity, or even lead to flow reversal for higher\nsalt concentration. This is helpful to raise the effective force profoundly in\nthe overscreening region."
    },
    {
        "anchor": "Interpretation of Quasielastic Scattering Spectra of Probe Species in\n  Complex Fluids: The objective of this paper is to correct an error in analyses of\nquasielastic scattering spectra. The error invokes a valid calculation under\nconditions in which its primary assumptions are incorrect, resulting in\nmisleading interpretations of spectra. Quasielastic scattering from dilute\nprobes yields the incoherent structure factor g^(1s)(q,t) = <exp(i q Dx(t))>,\nwith q being the magnitude of the scattering vector q and Dx(t) being the probe\ndisplacement parallel to q during a time interval t. The error is a claim that\ng^(1s)(q,t) ~ exp(- q^2 <(Dx(t))^2> /2) for probes in an arbitrary solution,\nleading to the incorrect belief that <(Dx(t))^2 > of probes in complex fluids\ncan be inferred from quasielastic scattering. The actual theoretical result\nrefers only to monodisperse probes in simple Newtonian liquids. In general,\ng^(1s)(q,t) is determined by all even moments <(Dx(t))^(2n) >, n = 1, 2, 3,...\nof the displacement distribution function P(Dx,t). Correspondingly, <(Dx(t))^2\n> cannot in general be inferred from g^(1s)(q,t). The theoretical model that\nties g^(1s)(q,t) to <(Dx(t))^2 > also quantitatively determines exactly how\n<(Dx(t))^2> /2 must behave, namely <(Dx(t))^2 > must increase linearly with t.\nIf the spectrum is not a single exponential in time, g^(1s)(q,t) does not\ndetermine <(Dx(t))^2>.",
        "positive": "Strain pattern in supercooled liquids: Investigations of strain correlations at the glass transition reveal\nunexpected phenomena. The shear strain fluctuations show an Eshelby-strain\npattern ($\\,\\sim \\cos{(4\\theta)}/r^2\\,$), characteristic for elastic response,\neven in liquids at long times [1]. We address this using a mode-coupling theory\nfor the strain fluctuations in supercooled liquids and data from both, video\nmicroscopy of a two-dimensional colloidal glass former and simulations of\nBrownian hard disks. We show that long-ranged and long-lived strain-signatures\nfollow a scaling law valid close to the glass transition. For large enough\nviscosities, the Eshelby-strain pattern is visible even on time scales longer\nthan the structural relaxation time $\\tau$ and after the shear modulus has\nrelaxed to zero."
    },
    {
        "anchor": "Shape-dependent oriented trapping and scaffolding of plasmonic\n  nanoparticles by topological defects for self-assembly of colloidal dimers in\n  liquid crystals: We demonstrate scaffolding of plasmonic nanoparticles by topological defects\ninduced by colloidal microspheres to match their surface boundary conditions\nwith a uniform far-field alignment in a liquid crystal host. Displacing\nenergetically costly liquid crystal regions of reduced order, anisotropic\nnanoparticles with concave or convex shapes not only stably localize in defects\nbut also self-orient with respect to the microsphere surface. Using laser\ntweezers, we manipulate the ensuing nanoparticle-microsphere colloidal dimers,\nprobing the strength of elastic binding and demonstrating self-assembly of\nhierarchical colloidal superstructures such as chains and arrays.",
        "positive": "Energetic rigidity II: Applications in examples of biological and\n  underconstrained materials: This is the second paper devoted to energetic rigidity, in which we apply our\nformalism to examples in two dimensions: underconstrained random regular spring\nnetworks, vertex models, and jammed packings of soft particles. Spring networks\nand vertex models are both highly underconstrained, and first-order constraint\ncounting does not predict their rigidity, but second-order rigidity does. In\ncontrast, spherical jammed packings are overconstrained and thus first-order\nrigid, meaning that constraint counting is equivalent to energetic rigidity as\nlong as prestresses in the system are sufficiently small. Aspherical jammed\npackings on the other hand have been shown to be jammed at hypostaticity, which\nwe use to argue for a modified constraint counting for systems that are\nenergetically rigid at quartic order."
    },
    {
        "anchor": "New Development of Monte Carlo Techniques for Studying Bottle-brush\n  Polymers: Due to the complex characteristics of bottle-brush polymers, it became a\nchallenge to develop an efficient algorithm for studying such macromolecules\nunder various solvent conditions or some constraints in the space by using\ncomputer simulations. In the limit of a bottle-brush polymer with a rather\nstiff backbone (straight rigid backbone), we generalize the variant of the\nbiased chain growth algorithm, the pruned-enriched Rosenbluth method, for\nsimulating polymers with complex architecture, from star polymers to\nbottle-brush polymers, on the simple cubic lattice. With the high statistics of\nour Monte Carlo results, we check the theoretical predictions of side chain\nbehavior and radial monomer density profile. For the comparison of the\nexperimental data for bottle-brush polymers with a flexible backbone and\nflexible side chains, based on the bond fluctuation model we propose another\nfast Monte Carlo algorithm combining the local moves, the pivot move, and an\nadjustable simulation lattice box. By monitoring the autocorrelation functions\nof gyration radii for the side chains and for the backbone, we see that for\nfixed side chain length there is no change in the behavior of these two\nfunctions as the backbone length increases. Our extensive results cover the\nrange which is accessible for the comparison to experimental data and for the\nchecking of the theoretically predicted scaling laws.",
        "positive": "Multi-component colloidal gels: interplay between structure and\n  mechanical proprieties: We present a detailed numerical study of multi-component colloidal gels\ninteracting sterically and obtained by arrested phase separation. Under\ndeformation, we found that the interplay between the different intertwined\nnetworks is key. Increasing the number of component leads to softer solids that\ncan accomodate progressively larger strain before yielding. The simulations\nhighlight how this is the direct consequence of the purely repulsive\ninteractions between the different components, which end up enhancing the\nlinear response of the material. Our work {provides new insight into mechanisms\nat play for controlling the material properties and open the road to new design\nprinciples for} soft composite solids"
    },
    {
        "anchor": "Structure and Dynamics of a Phase-Separating Active Colloidal Fluid: We examine a minimal model for an active colloidal fluid in the form of\nself-propelled Brownian hard spheres that interact purely through excluded\nvolume. Despite the absence of an aligning interaction, this system shows the\nsignature behaviors of an active fluid, including anomalous number fluctuations\nand phase separation behavior. Using simulations and analytic modeling, we\nquantify the phase diagram and separation kinetics. The dense phase is a unique\nmaterial that we call an active hexatic, which exhibits the structural\nsignatures of a crystalline solid near the crystal-hexatic transition point,\nbut the rheological and transport properties associated with a viscoelastic\nfluid.",
        "positive": "Universality Class of the Reversible-Irreversible Transition in Sheared\n  Suspensions: Collections of non-Brownian particles suspended in a viscous fluid and\nsubjected to oscillatory shear at very low Reynolds number have recently been\nshown to exhibit a remarkable dynamical phase transition separating reversible\nfrom irreversible behaviour as the strain amplitude or volume fraction are\nincreased. We present a simple model for this phenomenon, based on which we\nargue that this transition lies in the universality class of the conserved DP\nmodels or, equivalently, the Manna model. This leads to predictions for the\nscaling behaviour of a large number of experimental observables. Non-Brownian\nsuspensions under oscillatory shear may thus constitute the first experimental\nrealization of an inactive-active phase transition which is not in the\nuniversality class of conventional directed percolation."
    },
    {
        "anchor": "Edge fracture instability in sheared complex fluids: onset criterion and\n  possible mitigation strategy: We perform a detailed theoretical study of the edge fracture instability,\nwhich commonly destabilises the fluid-air interface during strong shear flows\nof entangled polymeric fluids, leading to unreliable rheological measurements.\nBy means of direct nonlinear simulations, we map out phase diagrams showing the\ndegree of edge fracture in the plane of the surface tension of the fluid-air\ninterface and the imposed shear rate, within the Giesekus and Johnson-Segalman\nmodels, for different values of the nonlinear constitutive parameters that\ndetermine the dependencies on shear rate of the shear and normal stresses. The\nthreshold for the onset of edge fracture is shown to be relatively robust\nagainst variations in the wetting angle where the fluid-air interface meets the\nhard walls of the flow cell, whereas the nonlinear dynamics depend strongly on\nwetting angle. We perform a linear stability calculation to derive an exact\nanalytical expression for the onset of edge fracture, expressed in terms of the\nshear-rate derivative of the second normal stress difference, the shear-rate\nderivative of the shear stress (sometimes called the tangent viscosity), the\njump in shear stress across the interface between the fluid and the outside\nair, the surface tension of that interface, and the rheometer gap size. Full\nagreement between our analytical calculation and nonlinear simulations is\ndemonstrated. We also elucidate in detail the mechanism of edge fracture, and\nfinally suggest a new way in which it might be mitigated in experimental\npractice. Some of the results in this paper were first announced in an earlier\nletter. The present manuscript provides additional simulation results,\ncalculational details of the linear stability analysis, and more detailed\ndiscussion of the significance and limitations of our findings.",
        "positive": "Interface Induced Anisotropy and nematic glass/gel state in Jammed\n  Aqueous Laponite Suspensions: Aqueous suspensions of Laponite, a system composed of disk-like\nnanoparticles, are found to develop optical birefringence over several days,\nwell after the suspensions solidified due to jamming. The optical anisotropy is\nparticularly enhanced near the air Laponite suspension interface over\nlength-scales of several millimetres, which is beyond five orders of magnitude\nlarger than the particle length scale, suggestive of large scale ordering\ninfluenced by the interface. The orientational order increases with time and is\nalways greater for higher concentration of salt, higher concentration of\nLaponite and higher temperature of the suspension. While weakly birefringent,\nLaponite suspensions covered by paraffin oil do not show any enhancement in the\noptical anisotropy near the interface compared to that in the bulk. We suggest\nthat the expedited structure formation near the air interface propagating\nprogressively inside the sample is responsible for the observed behaviour. We\ndiscuss the observed nematic ordering in the context of glasslike and gellike\nmicrostructure associated with aqueous Laponite suspensions."
    },
    {
        "anchor": "Nonlinear effective medium theory of disordered spring networks: Disordered soft materials, such as fibrous networks in biological contexts\nexhibit a nonlinear elastic response. We study such nonlinear behavior with a\nminimal model for networks on lattice geometries with simple Hookian elements\nwith disordered spring constant. By developing a mean-field approach to\ncalculate the differential elastic bulk modulus for the macroscopic network\nresponse of such networks under large isotropic deformations, we provide\ninsight into the origins of the strain stiffening and softening behavior of\nthese systems. We find that the nonlinear mechanics depends only weakly on the\nlattice geometry and is governed by the average network connectivity. In\nparticular, the nonlinear response is controlled by the isostatic connectivity,\nwhich depends strongly on the applied strain. Our predictions for the strain\ndependence of the isostatic point as well as the strain-dependent differential\nbulk modulus agree well with numerical results in both two and three\ndimensions. In addition, by using a mapping between the disordered network and\na regular network with random forces, we calculate the non-affine fluctuations\nof the deformation field and compare it to the numerical results. Finally, we\ndiscuss the limitations and implications of the developed theory.",
        "positive": "Active droploids: Active matter comprises self-driven units, such as bacteria and synthetic\nmicroswimmers, that can spontaneously form complex patterns and assemble into\nfunctional microdevices. These processes are possible thanks to the\nout-of-equilibrium nature of active-matter systems, fueled by a one-way\nfree-energy flow from the environment into the system. Here, we take the next\nstep in the evolution of active matter by realizing a two-way coupling between\nactive particles and their environment, where active particles act back on the\nenvironment giving rise to the formation of superstructures. In experiments and\nsimulations we observe that, under light-illumination, colloidal particles and\ntheir near-critical environment create mutually-coupled co-evolving structures.\nThese structures unify in the form of active superstructures featuring a\ndroplet shape and a colloidal engine inducing self-propulsion. We call them\nactive droploids -- a portmanteau of droplet and colloids. Our results provide\na pathway to create active superstructures through environmental feedback."
    },
    {
        "anchor": "Polyelectrolyte Knot Delocalization Induced by Counterion Condensation: Knots on ring polymers tend to be tight. For knots on charged polymers\n(polyelectrolytes), electrostatic repulsion among the monomers is considered to\nenhance the persistence length and further localize the knots. However, the\neffects of counterion condensation on knots behavior are not clear. Here we use\nmolecular dynamics simulations to systematically study the effect of counterion\ncondensation on the knot behavior under different electrostatic strength and\nsolvent quality conditions, with the focus on the knot sizes. We show that\ngenerally counterion condensation \\emph{delocalizes} the knots in systems with\nstrong electrostatic strength. At small to intermediate electrostatic strength,\nthe knot size and overall chain size and can be positive correlated or negative\ncorrelated, as a result of the interplay between electrostatic correlation and\nsolvent quality.",
        "positive": "Experiments and characterization of low-frequency oscillations in a\n  granular column: The behaviour of a vertically vibrated granular bed is reminiscent of a\nliquid in that it exhibits many phenomena such as convection and Faraday-like\nsurface waves. However, when the lateral dimensions of the bed are confined\nsuch that a quasi-one-dimensional geometry is formed, the only phenomena that\nremain are bouncing bed and the granular Leidenfrost effect. This permits the\nobservation of the granular Leidenfrost state for a wide range of energy\ninjection parameters, and more specifically allows for a thorough\ncharacterisation of the low-frequency oscillation (LFO) that is present in this\nstate. In both experiments and particle simulations we determine the LFO\nfrequency from the power spectral density of the centre of mass signal of the\ngrains, varying the amplitude and frequency of the driving, the particle\ndiameter and the number of layers in the system. We thus find that (i) the LFO\nfrequency is inversely proportional to the fast inertial time scale and (ii)\ndecorrelates with a typical decay time proportional to the slow dissipative\ntime scale in the system. The latter is consistent with the view that the LFO\nis driven by the inherent noise that is present in the granular Leidenfrost\nstate with a low number of particles."
    },
    {
        "anchor": "Fluid-solid transitions in photonic crystals of soft, thermoresponsive\n  microgels: Microgels are often discussed as well-suited model system for soft colloids.\nIn contrast to rigid spheres, the microgel volume and, coupled to this, the\nvolume fraction in dispersion can be manipulated by external stimuli. This\nbehavior is particularly interesting at high packings where phase transitions\ncan be induced by external triggers such as temperature in case of\nthermoresponsive microgels. A challenge, however, is the determination of the\nreal volume occupied by these deformable, soft objects and consequently, to\ndetermine the boundaries of the phase transitions. Here we propose core-shell\nmicrogels with a rigid silica core and a crosslinked, thermoresponsive\npoly-N-isopropylacrylamide (PNIPAM) shell with a carefully chosen shell-to-core\nsize ratio as ideal model colloids to study fluid-solid transitions that are\ninducible by millikelvin changes in temperature. Specifically, we identify the\ntemperature ranges where crystallization and melting occur using absorbance\nspectroscopy in a range of concentrations. Slow annealing from the fluid to the\ncrystalline state leads to photonic crystals with Bragg peaks in the visible\nwavelength range and very narrow linewidths. Small-angle X-ray scattering is\nthen used to confirm the structure of the fluid phase as well as the long-range\norder, crystal structure and microgel volume fraction in the solid phase.\nThanks to the scattering contrasts and volume ratio of the cores with respect\nto the shells, the scattering data do allow for form factor analysis revealing\nosmotic deswelling at volume fractions approaching and also exceeding the hard\nsphere packing limit.",
        "positive": "Polymer-Chain Configurations in Active and Passive Baths: The configurations taken by polymers embedded in out-of-equilibrium baths may\nhave broad effects in a variety of biological systems. As such, they have\nattracted considerable interest, particularly in simulation studies. Here we\nanalyze the distribution of configurations taken by a passive flexible chain in\na bath of hard, self-propelled, vibrated disks and systematically compare it to\nthat of the same flexible chain in a bath of hard, thermal-like, vibrated\ndisks. We demonstrate experimentally that the mean length and mean radius of\ngyration of both chains obey Flory's Law. However, the Kuhn length associated\nwith the number of correlated monomers is smaller in the case of the active\nbath, corresponding to a higher effective temperature. Importantly, the active\nbath does not just simply map on a hot equilibrium bath. Close examination of\nthe chains' configurations indicates a marked bias, with the chain in the\nactive bath more likely assuming configurations with a single prominent bend."
    },
    {
        "anchor": "Melting scenarios of two-dimensional Hertzian spheres with a single\n  triangular lattice: We present a molecular dynamics simulation study of the phase diagram and\nmelting scenarios of two-dimensional Hertzian spheres with exponent 7/2. We\nhave found multiple re-entrant melting of a single crystal with a triangular\nlattice in a wide range of densities from 0.5 to 10.0. Depending on the\nposition on the phase diagram, the triangular crystal has been shown to melt\nthrough both two-stage melting with a first-order hexatic - isotropic liquid\ntransition and a continuous solid - hexatic transition as well as in accordance\nwith the Berezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young (BKTHNY)\nscenario (two continuous transitions with an intermediate hexatic phase). We\nstudied the behavior of heat capacity and have shown that despite two-stage\nmelting, the heat capacity has one peak which seems to correspond to a\nsolid-hexatic transition.",
        "positive": "Scratching a 50-year itch with elongated rods: The classical Oseen-Frank theory of liquid crystal elasticity is based on the\nexperimentally verified fact that there are three independent modes of\ndistortion, each with its associated elastic constant. On the other hand, the\narguably more first-principles order parameter-based Landau-de Gennes theory\nonly involves two independent elastic modes. The resulting 'elastic constants\nproblem' has led to a considerable amount of vexation among theorists. In a\nseries of papers at the turn of the century, Fukuda and Yokoyama suggested that\nthe resolution of this problem could be found in the proper treatment of\nnon-local effects in the ideal part of the free energy. They used an ingenious,\nbut technically complex, technique based on a field-theoretic approach to\nsemi-flexible polymers. Here we revisit their idea but now in the more\naccessible framework of density functional theory of rigid particles. Our work\nrecovers their main results for rod-like particles, in that generically an\nordered assembly of non-interacting rods has three independent elastic\nconstants associated to it that all scale as the square of the length of the\nparticles and obey the inequalities $K_2 < K_1 < K_3$. We also consider the\ncase of disc-like particles, and then find in line with expectations that $K_3\n< K_1 < K_2$."
    },
    {
        "anchor": "Effect of Geometrical Constraint on Conformational Properties of a\n  Polymer Chain: In this paper, we analyze the effect of geometrical constraint on the\nconformational properties of an infinitely long linear semiflexible polymer\nchain confined in-between two constraints under good solvent condition in two\ndimensions. The constraints are two impenetrable stair shaped surface and for\ntwo dimensional space, the surface is a one dimensional line. The\nsemiflexibility of the chain is accounted by introducing a Boltzmann weight of\nbending energy required to produce each turn in the chain and good solvent\ncondition was accounted by using self avoiding walk model of the chain. We have\ncalculated exact critical value of step fugacity required for polymerization of\nan infinitely long polymer chain confined in between the constraints for\ndifferent values of separation between the constraints for directed version of\nthe model. We have also calculated possible maximum, minimum values of the\npersistent length for such chains and the maximum value of bending energy\nrequired for each turn in the chain for few values of separation between the\nconstraints.",
        "positive": "How to replace the oil droplet in Millikan's experiment with a single\n  virus: A highly sensitive optical capillary electrophoresis measurement method based\non a nanofluidic optical fiber platform is presented. By using scaling\narguments and considering realistic instrument limitations, I underline the\nfeasibility of measuring the electrophoretic mobility of a single\nfreely-diffusing nanoparticle or macromolecule in vitro, continuously and\nindefinitely, with microsecond time resolution. The high speed of this\ntechnique opens up new possibilities for studying reaction kinetics at the\nsingle molecule level."
    },
    {
        "anchor": "Lateral-Pressure Profiles in Cholesterol-DPPC Bilayers: By means of atomistic molecular dynamics simulations, we study\ncholesterol-DPPC (dipalmitoyl phosphatidylcholine) bilayers of different\ncomposition, from pure DPPC bilayers to a 1:1 mixture of DPPC and cholesterol.\nThe lateral-pressure profiles through the bilayers are computed and separated\ninto contributions from the different components. We find that the pressure\ninside the bilayer changes qualitatively for cholesterol concentrations of\nabout 20% or higher. The pressure profile then turns from a rather flat shape\ninto an alternating sequence of regions with large positive and negative\nlateral pressure. The changes in the lateral-pressure profile are so\ncharacteristic that specific interaction between cholesterol and molecules such\nas membrane proteins mediated solely via the lateral-pressure profile might\nbecome possible.",
        "positive": "Interference between a large number of independent Bose-Einstein\n  condensates: We study theoretically the interference patterns produced by the overlap of\nan array of Bose-Einstein condensates that have no phase coherence among them.\nWe show that density-density correlations at different quasimomenta, which play\nan important role in two-condensate interference, become negligible for large\n$N$, where $N$ is the number of overlapping condensates. In order to understand\nthe physics of this phenomenon, it is sufficient to consider the periodicity of\nthe lattice and the statistical probability distribution of a random-walk\nproblem. The average visibility of such interference patterns decreases as\n$N^{-1/2}$ for large $N$."
    },
    {
        "anchor": "The Effect of Ageing on the Structure and Properties of Model Liquid\n  Infused Surfaces: Liquid infused surfaces (LIS) exhibit unique properties that make them ideal\ncandidates for a wide range of applications, from anti-fouling and anti-icing\ncoatings to self-healing surfaces and controlled wetting. However, when exposed\nto realistic environmental conditions, LIS tend to age and progressively lose\ntheir desirable properties, potentially compromising their application. The\nassociated ageing mechanisms are still poorly understood, and results\nreflecting real-life applications are scarce. Here we track the ageing of model\nLIS composed of glass surfaces functionalized with hydrophobic nanoparticles\nand infused with silicone oil. The LIS are fully submerged in aqueous solutions\nand exposed to acoustic pressure waves for set time intervals. The ageing is\nmonitored by periodic measurements of the LIS' wetting properties. We also\ntrack changes to the LIS' nanoscale structure. We find that the LIS rapidly\nlose their slippery properties due to a combination of oil loss, smoothing of\nthe nanoporous functional layer and substrate degradation when directly exposed\nto the solution. The oil loss is consistent with water microdroplets entering\nthe oil layer and displacing oil away from the surface. These mechanisms are\ngeneral and could play a role in the ageing of most LIS.",
        "positive": "Restructuring and aging in a capillary suspension: The rheological properties of capillary suspensions, suspensions with small\namounts of an added immiscible fluid, are dramatically altered with the\naddition of the secondary fluid. We investigate a capillary suspension to\ndetermine how the network ages and restructures at rest and under applied\nexternal shear deformation. The present work uses calcium carbonate suspended\nin silicone oil (11 % solids) with added water as a model system. Aging of\ncapillary suspensions and their response to applied oscillatory shear is\ndistinctly different from particulate gels dominated by the van der Waals\nforces. The suspensions dominated by the capillary force are very sensitive to\noscillatory flow, with the linear viscoelastic regime ending at a deformation\nof only 0.1 % and demonstrating power-law aging behavior. This aging persists\nfor long times at low deformations or for shorter times with a sudden decrease\nin the strength at higher deformations. This aging behavior suggests that the\nnetwork is able to rearrange and even rupture. This same sensitivity is not\ndemonstrated in shear flow where very high shear rates are required to rupture\nthe agglomerates returning the apparent viscosity of capillary suspensions to\nthe same viscosity as for the pure vdW suspension. A transitional region is\nalso present at intermediate water contents wherein the material response\ndepends very strongly on the type, strength, and duration of the external\nforcing."
    },
    {
        "anchor": "Polymeric Liquids in Nanoporous Photonic Structures: From Precursor Film\n  Spreading to Imbibition Dynamics at the Nanoscale: Polymers are known to wet nanopores with high surface energy through an\natomically thin precursor film followed by slower capillary filling. We present\nhere light interference spectroscopy using a nanoporous membrane-based chip\nthat allows us to observe the dynamics of these phenomena in situ with\nsub-nanometer spatial and milli- to microsecond temporal resolution. The device\nconsists of a mesoporous silicon film (average pore size 6 nm) with an\nintegrated photonic crystal, which permits to simultaneously measure the phase\nshift of the thin-film interference and the resonance of the photonic crystal\nupon imbibition. For a styrene dimer, we find a flat fluid front without a\nprecursor film, while the pentamer forms an expanding molecular thin film\nmoving in front of the menisci of the capillary filling. These different\nbehaviors are attributed to a significantly faster pore-surface diffusion\ncompared to the imbibition dynamics for the pentamer and vice versa for the\ndimer. In addition, both oligomers exhibit anomalously slow imbibition\ndynamics, which could be explained by apparent viscosities of six and eleven\ntimes the bulk value, respectively. However, a more consistent description of\nthe dynamics is achieved by a constriction model that emphasizes the increasing\nimportance of local undulations in the pore radius with the molecular size and\nincludes a sub-nanometer hydrodynamic dead, immobile zone at the pore wall, but\notherwise uses bulk fluid parameters. Overall, our study illustrates that\ninterferometric, opto-fluidic experiments with nanoporous media allow for a\nremarkably detailed exploration of the nano-rheology of polymeric liquids.",
        "positive": "Constitutive theory of saturated porous media considering\n  porosity-dependent skeleton strain and chemical activity: In order to reveal the coupling effect among the chemical activity and the\nhydraulic seepage as well as the mechanical properties, a constitutive\ntheoretical framework considering the chemical activity for saturated porous\nmedia is derived from the mixture theory incorporated with the chemical\nthermodynamics. First, to highlight the important role of porosity in the\nhydro-mechanical-chemical multi-field coupling mechanism, the solid strain is\ndivided into the porosity-dependent skeleton strain, the matrix strain and the\nmass-exchange strain. The stress and strain state variables are determined from\nthe energy-conjugated form of the energy balance equation for establishing\nconstitutive equations. Second, under infinitesimal case, general elastic\nconstitutive equations including the relationship between mass fraction and its\nchemical potential are expressed by the free energy potential. Plastic model\nand the constitutive equation of thermodynamic flux and force are derived from\nthe dissipative potential. Finally, under the guide of this theoretical\nframework, the complete swelling constitutive models in the confined\ncompression are established for bentonite. The corresponding governing\nequations are formulated for multi-field two-phase saturated porous media.\nCompared with the experimental data, the proposed model can well reflect the\nchemical and mechanic coupling characteristics of representative elementary\nvolume in the different NaCl concentrations of solution for saturated\nbentonite."
    },
    {
        "anchor": "Application of a simple short-range attraction long-range repulsion\n  colloidal model towards predicting the viscosity of protein solutions: Some hard sphere colloidal models have been criticized for inaccurately\npredicting the solution viscosity of complex biological molecules like\nproteins. Competing short-range attractions and long-range repulsions, also\nknown as SALR interactions, have been thought to affect the microstructure of a\nprotein solution at low to moderate ionic strength. However, such interactions\nhave been implicated primarily in causing phase transition, protein gelation,\nor reversible cluster formation and their effect on protein solution viscosity\nchange is not fully understood. In this work we show the application of a hard\nsphere colloidal model with SALR interactions towards predicting the viscosity\nof dilute to semi-dilute protein solutions. The comparison is performed for a\nglobular shaped albumin and Y-shaped therapeutic monoclonal antibody that are\nnot explained by previous colloidal models. The model predictions show that it\nis the coupling between attractions and repulsions that give rise to the\nobserved experimental trends in solution viscosity as a function of pH,\nconcentration, and ionic strength. The parameters of the model are obtained\nfrom measurements of the second virial coefficient and net surface\ncharge/zeta-potential, without additional fitting of the viscosity.",
        "positive": "Pink noise of ionic conductance through single artificial nanopores\n  revisited: We report voltage-clamp measurements through single conical nanopore obtained\nby chemical etching of a single ion-track in polyimide film. Special attention\nis paid on the pink noise of the ionic current (i.e. $1/f$ noise) measured with\ndifferent filling liquids. The relative pink noise amplitude is almost\nindependent of concentration and pH for KCl solutions, but varies strongly\nusing ionic liquids. In particular we show that depending on the ionic liquid,\nthe transport of charge carriers is strongly facilitated (low noise and higher\nconductivity than in the bulk) or jammed. These results show that the origin of\nthe pink noise can be ascribed neither to fluctuations of the pore geometry nor\nto the pore wall charges but rather to a cooperative effect on ions motion."
    },
    {
        "anchor": "Reversible to Irreversible Transitions for Cyclically Driven Disks on\n  Periodic Obstacle Arrays: We examine the collective dynamics of disks moving through a square array of\nobstacles under cyclic square wave driving. Below a critical density we find\nthat system organizes into a reversible state in which the disks return to the\nsame positions at the end of every drive cycle. Above this density, the\ndynamics are irreversible and the disks do not return to the same positions\nafter each cycle. The critical density depends strongly on the angle $\\theta$\nbetween the driving direction and a symmetry axis of the obstacle array, with\nthe highest critical densities appearing at commensurate angles such as\n$\\theta=0^\\circ$ and $\\theta=45^\\circ$ and the lowest critical densities\nfalling at $\\theta = \\arctan(0.618)$, the inverse of the golden ratio, where\nthe flow is the most frustrated. As the density increases, the number of cycles\nrequired to reach a reversible state grows as a power law with an exponent near\n$\\nu=1.36$, similar to what is found in periodically driven colloidal and\nsuperconducting vortex systems.",
        "positive": "Viscosity-Mediated Growth and Coalescence of Surface Nanodroplets: Solvent exchange is a simple method to produce surface nanodroplets on a\nsubstrate for a wide range of applications by displacing a solution of good\nsolvent, poor solvent and oil (Solution A) by a poor solvent (Solution B). In\nthis work, we show that the growth and coalescence of nanodroplets on a\nhomogeneous surface is mediated by the viscosity of the solvent. We show that\nat high flow rates of viscous Solution B, the final droplet volume deviates\nfrom the scaling law that correlates final droplet volume to the flow rate of\nnon-viscous Solution B, reported in previous work. We attribute this deviation\nto a two-regime growth in viscous Solution B, where transition from an initial,\nfast regime to a final slow regime influenced by the flow rate. Moreover,\nviscous solution B hinders the coalescence of growing droplets, leading to a\ndistinct bimodal distribution of droplet size with stable nanodroplets, in\ncontrast to a continuous size distribution of droplets in non-viscous case. We\ndemonstrate that the group of small droplets produced in high viscosity\nenvironment may be applied for enhanced fluorescence detection with higher\nsensitivity and shorter response time. The finding of this work can potentially\nbe applied for mediating the size distribution of surface nanodroplets on\nhomogeneous surface without templates."
    },
    {
        "anchor": "Phonon-driven ultrafast exciton dissociation at donor-acceptor polymer\n  heterojunctions: A quantum-dynamical analysis of phonon-driven exciton dissociation at polymer\nheterojunctions is presented, using a hierarchical electron-phonon model\nparameterized for three electronic states and 24 vibrational modes. Two\ninterfering decay pathways are identified: a direct charge separation, and an\nindirect pathway via an intermediate bridge state. Both pathways depend\ncritically on the dynamical interplay of high-frequency C=C stretch modes and\nlow-frequency ring-torsional modes. The ultrafast, highly non-equilibrium\ndynamics is consistent with time-resolved spectroscopic observations.",
        "positive": "Active Turbulence: Active fluids exhibit spontaneous flows with complex spatiotemporal\nstructure, which have been observed in bacterial suspensions, sperm cells,\ncytoskeletal suspensions, self-propelled colloids, and cell tissues. Despite\noccurring in the absence of inertia, chaotic active flows are reminiscent of\ninertial turbulence, and hence they are known as active turbulence. Here, we\nsurvey the field, providing a unified perspective over different classes of\nactive turbulence. To this end, we divide our review in sections for systems\nwith either polar or nematic order, and with or without momentum conservation\n(wet/dry). Comparing to inertial turbulence, we highlight the emergence of\npower-law scaling with either universal or non-universal exponents. We also\ncontrast scenarios for the transition from steady to chaotic flows, and we\ndiscuss the absence of energy cascades. We link this feature to both the\nexistence of intrinsic length scales and the self-organized nature of energy\ninjection in active turbulence, which are fundamental differences with inertial\nturbulence. We close by outlining the emerging picture, remaining challenges,\nand future directions."
    },
    {
        "anchor": "Simulation of adsorbate-induced faceting on curved surfaces: A simple solid-on-solid model, proposed earlier to describe overlayer-induced\nfaceting of bcc(111) surface, is applied to faceting of spherical surfaces\ncovered by adsorbate monolayer. Monte Carlo simulation results show that\nmorphology of faceted surface depends on annealing temperature. At initial\nstage surface around the [111] pole consists of 3-sided pyramids and step-like\nfacets, then step-like facets dominate and their number decreases with\ntemperature, finally a single big pyramid is formed. It is shown that there is\nreversible phase transition at which faceted surface transforms to almost\nspherical one. It is found that temperature of this phase transition is an\nincreasing function of surface curvature. Simulation results show that\nmeasurements of high temperature properties performed directly and after fast\ncooling to low temperature lead to different results.",
        "positive": "What can we learn by squeezing a liquid: Relaxation times for different temperatures, T, and specific volumes, V,\ncollapse to a master curve versus TV^g, with g a material constant. The\nisochoric fragility, m_V, is also a material constant, inversely correlated\nwith g. From these we obtain a 3-parameter function, which fits accurately\nrelaxation times of several glass-formers over the supercooled regime, without\nany divergence below Tg. Although the 3 parameters depend on the material, only\ng significant varies; thus, by normalizing material-specific quantities related\nto g, a universal power law for the dynamics is obtained."
    },
    {
        "anchor": "Stability of jammed packings II: the transverse length scale: As a function of packing fraction at zero temperature and applied stress, an\namorphous packing of spheres exhibits a jamming transition where the system is\nsensitive to boundary conditions even in the thermodynamic limit. Upon further\ncompression, the system should become insensitive to boundary conditions\nprovided it is sufficiently large. Here we explore the linear response to a\nlarge class of boundary perturbations in 2 and 3 dimensions. We consider each\nfinite packing with periodic-boundary conditions as the basis of an infinite\nsquare or cubic lattice and study properties of vibrational modes at arbitrary\nwave vector. We find that the stability of such modes be understood in terms of\na competition between plane waves and the anomalous vibrational modes\nassociated with the jamming transition; infinitesimal boundary perturbations\nbecome irrelevant for systems that are larger than a length scale that\ncharacterizes the transverse excitations. This previously identified length\ndiverges at the jamming transition.",
        "positive": "Programming stiff inflatable shells from planar patterned fabrics: Lack of stiffness often limits thin shape-shifting structures to small\nscales. The large in-plane transformations required to distort the metrics are\nindeed commonly achieved by using soft hydrogels or elastomers. We introduce\nhere a versatile single-step method to shapeprogram stiff inflated structures,\nopening the door for numerous large scale applications, ranging from space\ndeployable structures to emergency shelters. This technique relies on channel\npatterns obtained by heat-sealing superimposed flat quasi-inextensible fabric\nsheets. Inflating channels induces an anisotropic in-plane contraction and thus\na possible change of Gaussian curvature. Seam lines, which act as a director\nfield for the in-plane deformation, encode the shape of the deployed structure.\nWe present three patterning methods to quantitatively and analytically program\nshells with non-Euclidean metrics. In addition to shapes, we describe with\nscaling laws the mechanical properties of the inflated structures. Large\ndeployed structures can resist their weight, substantially broadening the\npalette of applications."
    },
    {
        "anchor": "Two-dimensional structure in a generic model of triangular proteins and\n  protein trimers: Motivated by the diversity and complexity of two-dimensional crystals formed\nby triangular proteins and protein trimers, we have investigated the structures\nand phase behavior of hard-disk trimers. In order to mimic specific binding\ninteractions, each trimer possesses on `attractive' disk which can interact\nwith similar disks on other trimers via an attractive square-well potential. At\nlow density and low temperature, the fluid phase mainly consists of tetramers,\npentamers, or hexamers. Hexamers provide the structural motif for a\nhigh-density, low-temperature periodic solid phase, but we also identify a\nmetastable periodic structure based on a tetramer motif. At high density there\nis a transition between orientationally ordered and disordered solid phases.\nThe connections between simulated structures and those of 2D protein crystals\n-- as seen in electron microscopy -- are briefly discussed.",
        "positive": "Active nematics that modify their environment: a framework for\n  extra-cellular matrix remodeling: Many exemplary active systems, including living cells and animals, are able\nto form nematic order, while interacting with their environment. In this\nLetter, we explain how a dynamic coupling of an active nematic with its\nenvironment results in novel physical behavior. Deposition of aligned\nenvironment segments modifies the isotropic-nematic phase diagram and allows\nfor nematic order at arbitrarily low densities. The aligned environment acts as\nan external field that may also lead to arrested angular dynamics. We are\nmotivated mainly by cells that remodel collagen fibers in the extra-cellular\nmatrix (ECM), while being guided by the fibers during multicellular migration.\nOur predictions indicate that remodeling promotes macroscopic cellular order\nand ECM patterning, and possibly limits the coarsening of ordered ECM domains,\nin accordance with recent experiments."
    },
    {
        "anchor": "Chiral molecules on curved colloidal membranes: Colloidal membranes, self assembled monolayers of aligned rod like molecules,\noffer a template for designing membranes with definite shapes and curvature,\nand possibly new functionalities in the future. Often the constituent rods, due\nto their molecular chirality, are tilted with respect to the membrane normal.\nSpatial patterns of this tilt on curved membranes result from a competition\namong depletion forces, nematic interaction, molecular chirality and boundary\neffects. We present a covariant theory for the tilt pattern on minimal\nsurfaces, like helicoids and catenoids, which have been generated in the\nlaboratory only recently. We predict several non-uniform tilt patterns, some of\nwhich are consistent with experimental observations and some, which are yet to\nbe discovered.",
        "positive": "Effect of Annealing Induced Polymer Substrate Attachment on Swelling\n  Dynamics of Ultrathin Polymer Films: The effect of annealing on the dynamical behavior of swelling for ultrathin\npolyacrylamide films deposited on silicon substrates have been studied using\nX-ray reflectivity technique. The spin coated polyacrylamide films of similar\nthicknesses were annealed at various temperatures below and above the glass\ntransition temperature of the polymer. The electron density of the films was\nfound to increase systematically on annealing. The swelling dynamics of the\nannealed films were found to have systematic dependence on the temperature of\nannealing. The interaction between the substrate and the polymer molecules was\nfound to play important role in the swelling dynamics of the annealed films\nunlike our earlier observation with as coated films. The chain segments\nattached directly to the substrate were believed to have restricted freedom of\nmovements compared to the ones that are at a distance from the substrate and\nrelatively free. Accordingly, the dynamical behavior of swelling was modeled in\nterms of the combination of a free and a restricted component and was found to\nbe in excellent agreement with the data. The diffusion coefficients\ncorresponding to the restricted polymer segments were an order of magnitude\nsmaller than those of the free segments and the fraction of the same was found\nto increase with annealing at higher temperatures. The overall reduction of\nswellability of the films was explained in terms of the increase of density of\nthe films and the segmental attachment to the substrate on annealing."
    },
    {
        "anchor": "Explicit excluded volume of cylindrically symmetric convex bodies: We represent explicitly the excluded volume Ve{B1,B2} of two generic\ncylindrically symmetric, convex rigid bodies, B1 and B2, in terms of a family\nof shape functionals evaluated separately on B1 and B2. We show that Ve{B1,B2}\nfails systematically to feature a dipolar component, thus making illusory the\nassignment of any shape dipole to a tapered body in this class. The method\nproposed here is applied to cones and validated by a shape-reconstruction\nalgorithm. It is further applied to spheroids (ellipsoids of revolution), for\nwhich it shows how some analytic estimates already regarded as classics should\nindeed be emended.",
        "positive": "Pretransitional behavior of electrooptic Kerr effect in liquid thymol: Melting/freezing are canonical examples of discontinuous phase transitions,\nfor which no pretransitional effects in the liquid phase are expected.For the\nsolid phase, weak premelting effects are evidenced. This report shows\nlong-range, critical-like, pretransitional effect in liquid thymol detected in\nElectrooptic Kerr effect (EKE) studies. Notable is the negative sign of EKE\npretransitional anomaly. Studies are supplemented by high-resolution by\ndielectric constant temperature-related scan, which revealed a weak premelting\neffect in the solid phase. Both EKE and dielectric constant show a 'crossover'\nchange ca. 10K above the melting temperature. It can be recognized as the\nhallmark of the challenging Liquid-Liquid transition phenomenon ."
    },
    {
        "anchor": "Edge Contact Angle, Capillary Condensation, and Meniscus Depinning: We study the phase equilibria of a fluid confined in an open capillary slit\nformed when a wall of finite length $H$ is brought a distance $L$ away from a\nsecond macroscopic surface. This system shows rich phase equilibria arising\nfrom the competition between two different types of capillary condensation,\ncorner filling and meniscus depinning transitions depending on the value of the\naspect ratio $a=L/H$. For long capillaries, with $a<2/\\pi$, the condensation is\nof type I involving menisci which are pinned at the top edges at the ends of\nthe capillary characterized by an edge contact angle. For intermediate\ncapillaries, with $2/\\pi<a<1$, depending on the value of the contact angle the\ncondensation may be of type I or of type II, in which the menisci overspill\ninto the reservoir and there is no pinning. For short capillaries, with $a>1$,\ncondensation is always of type II. In all regimes, capillary condensation is\ncompletely suppressed for sufficiently large contact angles. We show that there\nis an additional continuous phase transition in the condensed liquid-like\nphase, associated with the depinning of each meniscus as they round the upper\nopen edges of the slit. Finite-size scaling predictions are developed for these\ntransitions and phase boundaries which connect with the fluctuation theories of\nwetting and filling transitions. We test several of our predictions using a\nfully microscopic Density Functional Theory which allows us to study the two\ntypes of capillary condensation and its suppression at the molecular level.",
        "positive": "Vesicle model with bending energy revisited: The equations governing the conditions of mechanical equilibrium in fluid\nmembranes subject to bending are revisited thanks to the principle of virtual\nwork. The note proposes systematic tools to obtain the shape equation and the\nline condition instead of Christoffel symbols and the complex calculations they\nentail. The method seems adequate to investigate all problems involving surface\nenergies."
    },
    {
        "anchor": "Finite amplitude inhomogeneous waves in Mooney-Rivlin viscoelastic\n  solids: New exact solutions are exhibited within the framework of finite\nviscoelasticity. More precisely, the solutions correspond to finite-amplitude,\ntransverse, linearly-polarized, inhomogeneous motions superposed upon a finite\nhomogeneous static deformation. The viscoelastic body is composed of a\nMooney-Rivlin viscoelastic solid, whose constitutive equation consists in the\nsum of an elastic part (Mooney-Rivlin hyperelastic model) and a viscous part\n(Newtonian viscous fluid model). The analysis shows that the results are\nsimilar to those obtained for the purely elastic case; inter alia, the normals\nto the planes of constant phase and to the planes of constant amplitude must be\northogonal and conjugate with respect to the B-ellipsoid, where B is the left\nCauchy-Green strain tensor associated with the initial large static\ndeformation. However, when the constitutive equation is specialized either to\nthe case of a neo-Hookean viscoelastic solid or to the case of a Newtonian\nviscous fluid, a greater variety of solutions arises, with no counterpart in\nthe purely elastic case. These solutions include travelling inhomogeneous\nfinite-amplitude damped waves and standing damped waves.",
        "positive": "Observation of a tricritical wedge filling transition in the 3D Ising\n  model: In this Letter we present evidences of the occurrence of a tricritical\nfilling transition for an Ising model in a linear wedge. We perform Monte Carlo\nsimulations in a double wedge where antisymmetric fields act at the top and\nbottom wedges, decorated with specific field acting only along the wegde axes.\nA finite-size scaling analysis of these simulations shows a novel critical\nphenomenon, which is distinct from the critical filling. We adapt to\ntricritical filling the phenomenological theory which successfully was applied\nto the finite-size analysis of the critical filling in this geometry, observing\ngood agreement between the simulations and the theoretical predictions for\ntricritical filling."
    },
    {
        "anchor": "Frustration and Melting of Colloidal Molecular Crystals: Using numerical simulations we show that a variety of novel colloidal\ncrystalline states and multi-step melting phenomena occur on square and\ntriangular two-dimensional periodic substrates. At half-integer fillings\ndifferent kinds of frustration effects can be realized. A two-step melting\ntransition can occur in which individual colloidal molecules initially rotate,\ndestroying the overall orientational order, followed by the onset of interwell\ncolloidal hopping, in good agreement with recent experiments.",
        "positive": "Early stages of the shear banding instability in wormlike micelles: We study the early stages of the shear banding instability in semidilute\nwormlike micelles using the non-local Johnson-Segalman model with a two-fluid\ncoupling of the concentration (phi) to the shear rate (gamma_dot) and micellar\nstrain (tensor{W}). We calculate the ``spinodal'' limit of stability for sweeps\nalong the homogeneous intrinsic flow curve. For startup ``quenches'' into the\nunstable region, the instability in general occurs before the homogeneous\nstartup flow can attain the intrinsic flow curve. We predict the selected time\nand length scales at which inhomogeneity first emerges. In the ``infinite\ndrag'' limit, fluctuations in the mechanical variables (gamma_dot and\n\\tensor{W}) are independent of those in phi, and are unstable when the slope of\nthe intrinsic flow curve is negative; but no length scale is selected. For\nfinite drag, the mechanical instability is enhanced by coupling to phi and a\nlength scale is selected, in qualitative agreement with recent experiments. For\nsystems far from an underlying zero-shear demixing instability this enhancement\nis slight, while close to demixing the instability sets in at low shear rates\nand is essentially demixing triggered by flow."
    },
    {
        "anchor": "Monte Carlo study of multiply crosslinked semiflexible polymer networks: We present a method to generate realistic, three-dimensional networks of\ncrosslinked semiflexible polymers. The free energy of these networks is\nobtained from the force-extension characteristics of the individual polymers\nand their persistent directionality through the crosslinks. A Monte Carlo\nscheme is employed to obtain isotropic, homogeneous networks that minimize the\nfree energy, and for which all of the relevant parameters can be varied: the\npersistence length, the contour length as well as the crosslinking length may\nbe chosen at will. We also provide an initial survey of the mechanical\nproperties of our networks subjected to shear strains, showing them to display\nthe expected non-linear stiffening behavior. Also, a key role for non-affinity\nand its relation to order in the network is uncovered.",
        "positive": "Pattern formation in colloidal explosions: We study the non-equilibrium pattern formation that emerges when magnetically\nrepelling colloids, trapped by optical tweezers, are abruptly released, forming\ncolloidal explosions. For multiple colloids in a single trap we observe a\npattern of expanding concentric rings. For colloids individually trapped in a\nline, we observe explosions with a zigzag pattern that persists even when\nmagnetic interactions are much weaker than those that break the linear symmetry\nin equilibrium. Theory and computer simulations quantitatively describe these\nphenomena both in and out of equilibrium. An analysis of the mode spectrum\nallows us to accurately quantify the non-harmonic nature of the optical traps.\nColloidal explosions provide a new way to generate well-characterized\nnon-equilibrium behaviour in colloidal systems."
    },
    {
        "anchor": "Influence of particle size polydispersity on dynamical heterogeneities\n  in dense particle packings: The dynamics of dense particle packings near the jamming transition is\ncharacterized by correlated particle motion. The growth of dynamical\nheterogeneities, or strong spatial variations in the motion of the particles\nconstituting the system, is a hallmark feature of slow glassy dynamics. We\nreport here a systematic confocal microscopy study that characterizes the\ncooperative dynamics of fluorescently-labelled colloidal particles in dense\naqueous suspensions. We demonstrate that jammed particulate suspensions can be\nfluidized by increasing the width of the particle size distribution. Our\nmolecular dynamics simulations, performed to numerically investigate the\neffects of continuous-size polydispersity on dense particle packing dynamics,\nshow an excellent match with our experimental results. Besides shedding light\non the fundamental aspects of particle-scale dynamics at the jamming-unjamming\ntransition, our findings are significant in the processing of\ncommonly-encountered dense suspensions such as paints, cosmetics, and food.",
        "positive": "Parametric Equations of the Theory of Formation of Spherical Micelles: Using the notion of aggregation work, we construct a system of differential\nequations for the aggregation number of micelles which is a function of the\nparameters of micellization (parametric equations). There are explicit\nsolutions for two important models of spherical micelles. Based on these\nsolutions, we obtain an analytical expression for the equilibrium concentration\nof surfactant monomers and consequently for the whole spectrum of equilibrium\nconcentrations of molecular aggregates in this framework. Accuracy of these\nexpressions is discussed, and they are applied on an example of micelles formed\nby sodium dodecyl sulfate."
    },
    {
        "anchor": "Shortcomings of the Bond Orientational Order Parameters for the Analysis\n  of Disordered Particulate Matter: Local structure characterization with the bond-orientational order parameters\nq4, q6, ... introduced by Steinhardt et al. has become a standard tool in\ncondensed matter physics, with applications including glass, jamming, melting\nor crystallization transitions and cluster formation. Here we discuss two\nfundamental flaws in the definition of these parameters that significantly\naffect their interpretation for studies of disordered systems, and offer a\nremedy. First, the definition of the bond-orientational order parameters\nconsiders the geometrical arrangement of a set of neighboring spheres NN(p)\naround a given central particle p; we show that procedure to select the spheres\nconstituting the neighborhood NN(p) can have greater influence on both the\nnumerical values and qualitative trend of ql than a change of the physical\nparameters, such as packing fraction. Second, the discrete nature of\nneighborhood implies that NN(p) is not a continuous function of the particle\ncoordinates; this discontinuity, inherited by ql, leads to a lack of robustness\nof the ql as structure metrics. Both issues can be avoided by a morphometric\napproach leading to the robust Minkowski structure metrics ql'. These ql' are\nof a similar mathematical form as the conventional bond-orientational order\nparameters and are mathematically equivalent to the recently introduced\nMinkowski tensors [Europhys. Lett. 90, 34001 (2010); Phys. Rev. E. 85, 030301\n(2012)].",
        "positive": "Two-point microrheology and the electrostatic analogy: The recent experiments of Crocker et al. suggest that microrheological\nmeasurements obtained from the correlated fluctuations of widely-separatedprobe\nparticles determine the rheological properties of soft, complex materials more\naccurately than do the more traditional particle autocorrelations. This\npresents an interesting problem in viscoelastic dynamics. We develop an\nimportant, simplifing analogy between the present viscoelastic problem and\nclassical electrostatics. Using this analogy and direct calculation we analyze\nboth the one and two particle correlations in a viscoelastic medium in order to\nexplain this observation."
    },
    {
        "anchor": "DNA-Protein Binding Rates: Bending Fluctuation and Hydrodynamic Coupling\n  Effects: We investigate diffusion-limited reactions between a diffusing particle and a\ntarget site on a semiflexible polymer, a key factor determining the kinetics of\nDNA-protein binding and polymerization of cytoskeletal filaments. Our theory\nfocuses on two competing effects: polymer shape fluctuations, which speed up\nassociation, and the hydrodynamic coupling between the diffusing particle and\nthe chain, which slows down association. Polymer bending fluctuations are\ndescribed using a mean field dynamical theory, while the hydrodynamic coupling\nbetween polymer and particle is incorporated through a simple heuristic\napproximation. Both of these we validate through comparison with Brownian\ndynamics simulations. Neither of the effects has been fully considered before\nin the biophysical context, and we show they are necessary to form accurate\nestimates of reaction processes. The association rate depends on the stiffness\nof the polymer and the particle size, exhibiting a maximum for intermediate\npersistence length and a minimum for intermediate particle radius. In the\nparameter range relevant to DNA-protein binding, the rate increase is up to\n100% compared to the Smoluchowski result for simple center-of-mass motion. The\nquantitative predictions made by the theory can be tested experimentally.",
        "positive": "On the relevance of generalized disclinations in defect mechanics: The utility of the notion of generalized disclinations in materials science\nis discussed within the physical context of modeling interfacial and bulk line\ndefects like defected grain and phase boundaries, dislocations and\ndisclinations. The Burgers vector of a disclination dipole in linear elasticity\nis derived, clearly demonstrating the equivalence of its stress field to that\nof an edge dislocation. We also prove that the inverse deformation/displacement\njump of a defect line is independent of the cut-surface when its g.disclination\nstrength vanishes. An explicit formula for the displacement jump of a single\nlocalized composite defect line in terms of given g.disclination and\ndislocation strengths is deduced based on the Weingarten theorem for\ng.disclination theory (Weingarten-gd theorem) at finite deformation. The\nBurgers vector of a g.disclination dipole at finite deformation is also\nderived."
    },
    {
        "anchor": "Efficient and accurate simulation of dynamic dielectric objects: Electrostatic interactions between dielectric objects are complex and of a\nmany-body nature, owing to induced surface bound charge. We present a\ncollection of techniques to simulate dynamical dielectric objects. We calculate\nthe surface bound charge from a matrix equation using the Generalized Minimal\nResidue method (GMRES). Empirically, we find that GMRES converges very quickly.\nIndeed, our detailed analysis suggests that the relevant matrix has a very\ncompact spectrum for all non-degenerate dielectric geometries. Each GMRES\niteration can be evaluated using a fast Ewald solver with cost that scales\nlinearly or near-linearly in the number of surface charge elements. We analyze\nseveral previously proposed methods for calculating the bound charge, and show\nthat our approach compares favorably.",
        "positive": "Non-monotonic fluctuation spectra of membranes pinned or tethered\n  discretely to a substrate: The thermal fluctuation spectrum of a fluid membrane coupled harmonically to\na solid support by an array of tethers is calculated. For strong tethers, this\nspectrum exhibits non-monotonic, anisotropic behavior with a relative maximum\nat a wavelength about twice the tether distance. The root mean square\ndisplacement is evaluated to estimate typical membrane displacements. Possible\napplications cover pillar-supported or polymer-tethered membranes."
    },
    {
        "anchor": "Spiral cracks in drying precipitates: We investigate the formation of spiral crack patterns during the desiccation\nof thin layers of precipitates in contact with a substrate. This\nsymmetry-breaking fracturing mode is found to arise naturally not from torsion\nforces, but from a propagating stress front induced by the fold-up of the\nfragments. We model their formation mechanism using a coarse-grain model for\nfragmentation and successfully reproduce the spiral cracks. Fittings of\nexperimental and simulation data show that the spirals are logarithmic,\ncorresponding to constant deviation from a circular crack path. Theoretical\naspects of the logarithmic spirals are discussed. In particular we show that\nthis occurs generally when the crack speed is proportional to the propagating\nspeed of stress front.",
        "positive": "Hydrodynamic instabilities in miscible fluids: Hydrodynamic instabilities in miscible fluids are ubiquitous, from natural\nphenomena up to geological scales, to industrial and technological\napplications, where they represent the only way to control and promote mixing\nat low Reynolds numbers, well below the transition from laminar to turbulent\nflow. As for immiscible fluids, the onset of hydrodynamic instabilities in\nmiscible fluids is directly related to the physics of their interfaces. The\nfocus of this review is therefore on the general mechanisms driving the growth\nof disturbances at the boundary between miscible fluids, under a variety of\nforcing conditions. In the absence of a regularizing mechanism, these\ndisturbances would grow indefinitely. For immiscible fluids, interfacial\ntension provides such a regularizing mechanism, because of the energy cost\nassociated to the creation of new interface by a growing disturbance. For\nmiscible fluids, however, the very existence of interfacial stresses that mimic\nan effective surface tension is debated. Other mechanisms, however, may also be\nrelevant, such as viscous dissipation. We shall review the stabilizing\nmechanisms that control the most common hydrodynamic instabilities,\nhighlighting those cases for which the lack of an effective interfacial tension\nposes deep conceptual problems in the mathematical formulation of a linear\nstability analysis. Finally, we provide a short overview on the ongoing\nresearch on the effective, out of equilibrium interfacial tension between\nmiscible fluids."
    },
    {
        "anchor": "A schematic model for molecular affinity and binding with Ising\n  variables: After discussing the relevance of statistical physics in molecular\nrecognition processes, we present a schematic model for ligand-receptor\nassociation based on an Ising chain. We discuss the possible behaviors of the\naffinity when the stiffness of the ligand increases. We also consider the case\nof flexible receptors. A variety of interesting behaviors is obtained,\nincluding some affinity modulation upon bond hardening of softening. The\naffinity of a ligand for its receptor is shown to depend on the details of\ntheir rigidity profile, and we question the possibility of encoding information\nin the rigidities as well as in the shape. An exhaustive study of the\nselectivity of patterns with length $n<8$ is carried on. Connection with other\nspin models, in particular spin glasses is mentioned in conclusion.",
        "positive": "Unwinding relaxation dynamics of polymers: The relaxation dynamics of a polymer wound around a fixed obstacle\nconstitutes a fundamental instance of polymer with twist and torque and it is\nof relevance also for DNA denaturation dynamics. We investigate it by\nsimulations and Langevin equation analysis. The latter predicts a relaxation\ntime scaling as a power of the polymer length times a logarithmic correction\nrelated to the equilibrium fluctuations of the winding angle. The numerical\ndata support this result and show that at short times the winding angle\ndecreases as a power-law. This is also in agreement with the Langevin equation\nprovided a winding-dependent friction is used, suggesting that such reduced\ndescription of the system captures the basic features of the problem."
    },
    {
        "anchor": "Dielectric secondary relaxation of water in aqueous binary glass-formers: The dielectric relaxation of water in glassy aqueous binary mixtures exhibits\nan Arrhenius behaviour with a nearly universal activation energy. We here\ndemonstrate that its characteristic relaxation time follows a remarkably\ngeneral functional dependence on the weight fraction of water for a wide range\nof molecular systems.",
        "positive": "Point Defects in Crystals of Charged Colloids: Charged colloidal particles - both on the nano and micron scales - have been\ninstrumental in enhancing our understanding of both atomic and colloidal\ncrystals. These systems can be straightforwardly realized in the lab, and tuned\nto self-assemble into body-centered cubic (BCC) and face-centered cubic (FCC)\ncrystals. While these crystals will always exhibit a finite number of point\ndefects, including vacancies and interstitials - which can dramatically impact\ntheir material properties - their existence is usually ignored in scientific\nstudies. Here, we use computer simulations and free-energy calculations to\ncharacterize vacancies and interstitials in both FCC and BCC crystals of\npoint-Yukawa particles. We show that, in the BCC phase, defects are\nsurprisingly more common than in the FCC phase, and the interstitials manifest\nas so-called crowdions: an exotic one-dimensional defect proposed to exist in\natomic BCC crystals. Our results open the door to directly observing these\nelusive defects in the lab."
    },
    {
        "anchor": "Sound velocities of Lennard-Jones systems near the liquid-solid phase\n  transition: Longitudinal and transverse sound velocities of Lennard-Jones systems are\ncalculated at the liquid-solid coexistence using the additivity principle. The\nresults are shown to agree well with the ``exact'' values obtained from their\nrelations to excess energy and pressure. Some consequences, in particular, in\nthe context of the Lindemann's melting rule and Stokes-Einstein relation\nbetween the self-diffusion and viscosity coefficients are discussed. Comparison\nwith available experimental data on the sound velocities of solid argon at\nmelting conditions is provided.",
        "positive": "How attractive and repulsive interactions affect structure ordering and\n  dynamics of glass-forming liquids?: The theory developed in our previous papers is applied in this paper to\ninvestigate the dependence of slowing down of dynamics of glass-forming liquids\non the attractive and repulsive parts of intermolecular interactions. Through\nan extensive comparison of the behavior of a Lennard-Jones glass-forming liquid\nand that of its WCA reduction to a model with truncated pair potential without\nattractive tail, we demonstrate why the two systems exhibit very different\ndynamics despite having nearly identical pair correlation functions. In\nparticular, we show that local structures characterized by number of mobile and\nimmobile particles around a central particle markedly differ in the two systems\nat densities and temperatures where their dynamics show large difference and\nnearly identical where dynamics nearly overlap. We also show how the parameter\n{\\psi}(T ) that measures the role of fluctuations embedded in the system on\nsize of the cooperatively reorganizing cluster (CRC) and the crossover\ntemperature T a depend on the intermolecular interactions. These parameters\nstemming from the intermolecular interactions characterize the temperature and\ndensity dependence of structural relaxation time {\\tau} {\\alpha}. The\nquantitative and qualitative agreements found with simulation results for the\ntwo systems suggest that our theory brings out the underlying features that\ndetermine dynamics of glass-forming liquids."
    },
    {
        "anchor": "Dynamics in shear flow studied by X-ray Photon Correlation Spectroscopy: X-ray photon correlation spectroscopy was used to measure the diffusive\ndynamics of colloidal particles in a shear flow. The results presented here\nshow how the intensity autocorrelation functions measure both the diffusive\ndynamics of the particles and their flow-induced, convective motion. However,\nin the limit of low flow/shear rates, it is possible to obtain the diffusive\ncomponent of the dynamics, which makes the method suitable for the study of the\ndynamical properties of a large class of complex soft-matter and biological\nfluids. An important benefit of this experimental strategy over more\ntraditional X-ray methods is the minimization of X-ray induced beam damage.\nWhile the method can be applied also for photon correlation spectroscopy in the\nvisible domain, our analysis shows that the experimental conditions under which\nit is possible to measure the diffusive dynamics are easier to achieve at\nhigher q values (with X-rays).",
        "positive": "Brownian dynamics study of driven partially pinned solid in the presence\n  of square array of pinning centers: Enhanced pinning close to the melting\n  transition: A set of interacting vortices in $2D$ in the presence of a substrate with\nsquare symmetry and at filling ratio $1$ can display a low temperature solid\nphase where only one of the reciprocal lattice vectors of the substrate is\npresent\\cite{toby1,fasano}. This partially pinned vortex lattice melts to a\nmodulated liquid via a continuous transition \\cite{toby1}. Brownian dynamics\nsimulation is carried out to study the behavior of driven partially pinned\nsolid at different temperatures. The average vortex velocity for forces above\nthe depinning threshold shows a non-monotonic behavior with temperature, with a\nminimum in the average velocity close to the melting point. This is reminiscent\nof the peak effect seen in vortex systems with random disorder. This effect in\nthe current system can be qualitatively explained by an effective increase in\nthe barriers encountered by the particles as $T_c$ is approached. Approximate\ncalculation of the energy barriers as a function of temperature, from the\nsimulation supports this claim."
    },
    {
        "anchor": "Effects of static and temporally fluctuating tensions on semiflexible\n  polymer looping: Biopolymer looping is a dynamic process that occurs ubiquitously in cells for\ngene regulation, protein folding, etc. In cellular environments, biopolymers\nare often subject to tensions which are either static, or temporally\nfluctuating far away from equilibrium. We study the dynamics of semiflexible\npolymer looping in the presence of such tensions by using Brownian dynamics\nsimulation combined with an analytical theory. We show a minute tension\ndramatically changes the looping time, especially for long chains. Considering\na dichotomically flipping noise as a simple example of the nonequilibrium\ntension, we find the phenomenon of resonant activation, where the looping time\ncan be the minimum at an optimal flipping time. We discuss our results in\nconnection with recent experiments.",
        "positive": "Classical density functional theory for a two-dimensional isotropic\n  ferrogel model with labeled particles: In this study, we formulate a density functional theory (DFT) for systems of\nlabeled particles, considering a two-dimensional bead-spring lattice with a\nmagnetic dipole on every bead as a model for ferrogels. On the one hand, DFT\nhas been widely studied to investigate fluid-like states of materials, in which\nconstituent particles are not labeled as they can exchange their positions\nwithout energy cost. On the other hand, in ferrogels consisting of magnetic\nparticles embedded in elastic polymer matrices, the particles are labeled by\ntheir positions as their neighbors do not change over time. We resolve such an\nissue of particle labeling, introducing a mapping of the elastic interaction\nmediated by the springs onto a pairwise additive interaction (pseudo-springs)\nbetween unlabeled particles. We further investigate magnetostriction and\nchanges in the elastic constants under altered magnetic interactions employing\nthe pseudo-spring potential. It is revealed that there are two different\nresponse scenarios in the mechanical properties of the dipole-spring systems:\nwhile systems at low packing fractions are hardened as the magnetic moments\nincrease in magnitude, at high packing fractions softening due to diminishing\neffects from the steric force, associated with increases in the volume, is\nobserved. Validity of the theory is also verified by Monte-Carlo simulations\nwith both real and pseudo-springs. We expect that our DFT approach may shed\nlight on an understanding of materials with particle inclusions."
    },
    {
        "anchor": "How temperature rise induces phase separation in acidic aqueous biphasic\n  solutions: Ionic-liquid based acidic aqueous biphasic solutions (AcABS) recently offered\na breakthrough in the field of metal recycling. Indeed, the mixture of\ntributyltetradecylphosphonium chloride (P$_{44414}$Cl) and acid with water\ncontent larger than 60 \\% presents a phase separation with very good extraction\nefficiency for metallic ions. Moreover, this ternary solution presents a Lower\nSolution Critical Temperature (LCST), meaning that the biphasic area of the\nphase diagram increases upon increase of temperature, in other terms the phase\nseparation from a homogeneous liquid can be induced by an elevation of\ntemperature, typically a few tens of degrees. We address here the microscopic\nmechanisms driving the phase separation. Small Angle Neutron Scattering\nprovides us with structural information for various acid content and\ntemperature. We characterized the spherical micelle formation in the binary\nionic liquid/water solution and the micelle aggregation upon addition of acid,\ndue of the screening of electrostatic repulsion. If addition of salt leads to\nidentical transitions in the solution, the ionic strength is not a relevant\nparameter and more subtle effects such as ion size or polarizability have to be\ntaken into account to rationalize the phase diagram. The increase of both acid\nconcentration and/or temperature eventually leads to the micelle flocculation\nand phase separation. This last step is achieved through chloride ion\nadsorption at the surface of the micelle with an enthalpy of adsorption of\n$\\sim$ 12 kJ/mol. The attraction between micelles can be well understood in\nterms of DLVO potential. This exothermic adsorption compensates the entropic\ncost, leading to the counter-intuitive behavior of the system.",
        "positive": "Dynamical structure factors of $S=1/2$ two-leg spin ladder systems: We investigate dynamical properties of $S=1/2$ two-leg spin ladder systems.\nIn a strong coupling region, an isolated mode appears in the lowest excited\nstates, while in a weak coupling region, an isolated mode is reduced and the\nlowest excited states become a lower bound of the excitation continuum. We find\nin the system with equal intrachain and interchain couplings that due to a\ncyclic four-spin interaction, the distribution of the weights for the dynamical\nstructure factor and characteristics of the lowest excited states are strongly\ninfluenced. The dynamical properties of two systems proposed for ${\\rm\nSrCu_2O_3}$ are also discussed."
    },
    {
        "anchor": "The totally asymmetric exclusion process on a ring: Exact relaxation\n  dynamics and associated model of clustering transition: The totally asymmetric simple exclusion process in discrete time is\nconsidered on finite rings with fixed number of particles. A\ntranslation-invariant version of the backward-ordered sequential update is\ndefined for periodic boundary conditions. We prove that the so defined update\nleads to a stationary state in which all possible particle configurations have\nequal probabilities. Using the exact analytical expression for the propagator,\nwe find the generating function for the conditional probabilities, average\nvelocity and diffusion constant at all stages of evolution. An exact and\nexplicit expression for the stationary velocity of TASEP on rings of arbitrary\nsize and particle filling is derived. The evolution of small systems towards a\nsteady state is clearly demonstrated. Considering the generating function as a\npartition function of a thermodynamic system, we study its zeros in planes of\ncomplex fugacities. At long enough times, the patterns of zeroes for rings with\nincreasing size provide evidence for a transition of the associated\ntwo-dimensional lattice paths model into a clustered phase at low fugacities.",
        "positive": "Co-nonsolvency of PNiPAM at the transition between solvation mechanisms: We investigate the co-nonsolvency of poly-N-isopropyl acrylamide (PNiPAM) in\ndifferent water-alcohol mixtures and show that this phenomenon is due to two\ndistinct solvation contributions governing the phase behavior of PNiPAM in the\nwater-rich and alcohol-rich regime respectively. While hydrophobic hydration is\nthe predominant contribution governing the phase behavior of PNiPAM in the\nwater-rich regime, the mixing contributions governing the phase behavior of\nclassical polymer solutions determine the phase behavior of PNiPAM in the\nalcohol-rich regime. This is evidenced by distinct scaling relations denoting\nthe energetic state of the aqueous medium as a key parameter for the phase\nbehavior of PNiPAM in the water-rich regime, while the volume fractions of\nrespectively water, alcohol and PNiPAM become relevant parameters in the\nalcohol-rich regime. Adding alcohol to water decreases the energetics of the\naqueous medium, which gradually suppresses hydrophobic hydration, while adding\nwater to alcohol decreases the solvent quality. Consequently, PNiPAM is\ninsoluble in the intermediate range of solvent composition, where neither\nhydrophobic hydration nor the mixing contributions prevail. This accounts for\nthe co-nonsolvency phenomenon observed for PNiPAM in water-alcohol mixtures."
    },
    {
        "anchor": "Dynamics of a particle moving in a two dimensional Lorentz lattice gas: We study the dynamics of a particle moving in a square two-dimensional\nLorentz lattice-gas. The underlying lattice-gas is occupied by two kinds of\nrotators, \"right-rotator (R)\" and \"left-rotator (L)\" and some of the sites are\nempty {\\it{viz.}} vacancy \"V\".The density of $R$ and $L$ are the same and\ndensity of $V$ is one of the key parameters of our model. The rotators\ndeterministically rotate the direction of a particle's velocity to the right or\nleft and vacancies leave it unchanged. We characterise the dynamics of particle\nmotion for different densities of vacancies. Since the system is deterministic,\nthe particle forms a closed trajectory asymptotically. The probability of the\nparticle being in a closed or open trajectory at time $t$ is a function of the\ndensity of vacancies. \\textcolor{black}{The motion of the particle is\n{\\it{uniform}} throughout in a fully occupied lattice. However, it is divided\nin two distinct phases in partially vacant lattices}: The first phase of the\nmotion, which is the focus of this study, is characterised by anomalous\ndiffusion and a power-law decay of the probability of being in an open\ntrajectory. The second phase of the motion is characterised by subdiffusive\nmotion and an exponential decay of the probability of being in an open\ntrajectory. For lattices with a non-zero density of vacancies, the first phase\nof motion lasts for a longer period of time as the density of vacancies\nincreases.",
        "positive": "Theory of nonlinear rheology and yielding of dense colloidal suspensions: A first principles approach to the nonlinear flow of dense suspensions is\npresented which captures shear thinning of colloidal fluids and dynamical\nyielding of colloidal glasses. The advection of density fluctuations plays a\ncentral role, suppressing the caging of particles and speeding up structural\nrelaxation. A mode coupling approach is developed to explore these effects."
    },
    {
        "anchor": "Interaction between charge-regulated metal nanoparticles in an\n  electrolyte solution: We present a theory which allows us to calculate the interaction potential\nbetween charge-regulated metal nanoparticles inside an acid-electrolyte\nsolution. The approach is based on the recently introduced model of charge\nregulation which permits us to explicitly -- within a specific microscopic\nmodel -- relate the bulk association constant of a weak acid to the surface\nassociation constant for the same weak acid adsorption sites. When considering\nmetal nanoparticles we explicitly account for the effect of the induced surface\ncharge in the conducting core. To explore the accuracy of the approximations,\nwe compare the ionic density profiles of an isolated charge-regulated metal\nnanoparticle with explicit Monte Carlo simulations of the same model. Once the\naccuracy of the theoretical approach is established, we proceed to calculate\nthe interaction force between two charge-regulated metal nanoparticles by\nnumerically solving the Poisson-Boltzmann equation with charge regulation\nboundary condition. The force is then calculated by integrating the\nelectroosmotic stress tensor. We find that for metal nanoparticles the charge\nregulation boundary condition can be well approximated by the constant surface\ncharge boundary condition, for which a very accurate Derjaguin-like\napproximation was recently introduced. On the other hand, a constant surface\npotential boundary condition often used in colloidal literature, shows a\nsignificant deviation from the charge regulation boundary condition for\nparticles with large charge asymmetry.",
        "positive": "Universal contact-line dynamics at the nanoscale: The relaxation dynamics of the contact angle between a viscous liquid and a\nsmooth substrate is studied at the nanoscale. Through atomic force microscopy\nmeasurements of polystyrene nanostripes we monitor simultaneously the temporal\nevolution of the liquid-air interface as well as the position of the contact\nline. The initial configuration exhibits high curvature gradients and a\nnon-equilibrium contact angle that drive liquid flow. Both these conditions are\nrelaxed to achieve the final state, leading to three successive regimes along\ntime: i) stationary-contact-line levelling; ii) receding-contact-line\ndewetting; iii) collapse of the two fronts. For the first regime, we reveal the\nexistence of a self-similar evolution of the liquid interface, which is in\nexcellent agreement with numerical calculations from a lubrication model. For\ndifferent liquid viscosities and film thicknesses we provide evidence for a\ntransition to dewetting featuring a universal critical contact angle and\ndimensionless time."
    },
    {
        "anchor": "Energy Dissipation in Driven Granular Matter in the Absence of Gravity: We experimentally investigate the energy dissipation rate in sinusoidally\ndriven boxes which are partly filled by granular material under conditions of\nweightlessness. We identify two different modes of granular dynamics, depending\non the amplitude of driving, $A$. For intense forcing, A>A_0, the material is\nfound in the collect-and-collide regime where the center of mass of the\ngranulate moves synchronously with the driven container while for weak forcing,\nA<A_0, the granular material exhibits gas-like behavior. Both regimes\ncorrespond to different dissipation mechanisms, leading to different scaling\nwith amplitude and frequency of the excitation and with the mass of the\ngranulate. For the collect-and-collide regime, we explain the dependence on\nfrequency and amplitude of the excitation by means of an effective one-particle\nmodel. For both regimes, the results may be collapsed to a single curve\ncharacterizing the physics of granular dampers.",
        "positive": "Propagation Length of Self-healing Slip Pulses at the Onset of Sliding:\n  A Toy Model: Macroscopic sliding between two solids is triggered by the propagation of a\nmicro-slip front along the frictional interface. In certain conditions, sliding\nis preceded by the propagation of aborted fronts, spanning only part of the\ncontact interface. The selection of the characteristic size spanned by those\nso-called precursors remains poorly understood. Here, we introduce a 1D toy\nmodel of precursors between a slider and a track in which the fronts are\nquasi-static self-healing slip pulses. When the slider's thickness is large\ncompared to the elastic correlation length and when the interfacial stiffness\nis small compared with the bulk stiffness, we provide an analytical solution\nfor the length of the first precursor, {\\Lambda}, and the shear stress field\nassociated with it. These quantities are given as a function of the bulk\nmaterial parameters, the frictional properties of the interface and the\nmacroscopic loading conditions. Analytical results are in quantitative\nagreement with the numerical solution of the model. In contrast with previous\nmodels, our model predicts that {\\Lambda} does not depend on the frictional\nbreaking threshold of the interface. Our results should be relevant to the\nvarious systems in which self-healing slip pulses have been observed."
    },
    {
        "anchor": "Large deformation analysis of spontaneous twist and contraction in\n  nematic elastomer fibres with helical director: A cylindrical rubber fibre subject to twist will also elongate: a\nmanifestation of Poynting's effect in large strain elasticity. Here, we\nconstruct an analogous treatment for an active rubber fibre actuated via an\naxisymmetric pattern of spontaneous distortion. We start by constructing an\nexact large-deformation solution to the equations of elasticity for such fibre\nsubject to imposed twist and stretch, which reveals spontaneous warping and\ntwisting of the fibre cross-section absent in passive rubbers. We then compute\nthe corresponding non-linear elastic energy, which encompasses the Poynting\neffect, but is minimized by a finite spontaneous twist and stretch. In the\nsecond half of the paper, we apply these results to understand the\ntwist-contraction actuation of nematic elastomer fibres fabricated with\ndirector-fields that encode helical patterns of contraction on heating. We\nfirst consider patterns making a constant angle with respect to the local\ncylindrical coordinate system (conical spiral director curves) and verify the\npredicted spontaneous twist, contraction and cross-section deformation via\nfinite elements. Secondly, we consider realistic director distributions for the\nexperimentally reported fibres fabricated by cross-linking while simultaneously\napplying stretch and twist. Counter-intuitively, we find that maximum actuation\ntwist is produced by applying a finite optimal twist during fabrication.\nFinally, we illustrate that spontaneously twisting fibres will coil into\nspring-like shapes on actuation if the ends are prevented from twisting\nrelative to each other. Such twist-torsion coupling would allow to make a\ntendril-like \"soft-spring\" actuator with low force and high linear stroke\ncompared to the intrinsic contraction of the elastomer itself.",
        "positive": "Unfolding Polyelectrolytes in Trivalent Salt Solutions Using DC Electric\n  Fields: A Study by Langevin Dynamics Simulations: We study the behavior of single linear polyelectrolytes condensed by\ntrivalent salt under the action of electric fields through computer\nsimulations. The chain is unfolded when the strength of the electric field is\nstronger than a critical value. This critical electric field follows a scaling\nlaw against chain length and the exponent of the scaling law is $-0.77(1)$,\nsmaller than the theoretical prediction, $-3\\nu/2$ [Netz, Phys. Rev. Lett. 90\n(2003) 128104], and the one obtained by simulations in tetravalent salt\nsolutions, $-0.453(3)$ [Hsiao and Wu, J. Phys. Chem. B 112 (2008) 13179]. It\ndemonstrates that the scaling exponent depends sensitively on the salt valence.\nHence, it is easier to unfold chains condensed by multivalent salt of smaller\nvalence. Moreover, the absolute value of chain electrophoretic mobility\nincreases drastically when the chain is unfolded in an electric field. The\ndependence of the mobility on electric field and chain length provides a\nplausible way to impart chain-length dependence in free-solution\nelectrophoresis via chain unfolding transition induced by electric fields.\nFinally, we show that, in addition to an elongated structure, a condensed chain\ncan be unfolded into an U-shaped structure. The formation of this structure in\nour study is purely a result of the electric polarization, but not of the\nelasto-hydrodynamics dominated in sedimentation of polymers."
    },
    {
        "anchor": "Monolayers of 3He on the Surface of Bulk Superfluid 4He: We have used quantum evaporation to investigate the two-dimensional fermion\nsystem that forms at the free surface of (initially isotopically pure) 4He when\nsmall quantities of 3He are added to it. By measuring the first-arrival times\nof the evaporated atoms, we have determined that the 3He-3He potential in this\nsystem is V_3S/k_B=(0.23+/-0.02) K nm^2 (repulsive) and estimated a value of\nm_3S=(1.53+/-0.02)m_3 for the zero-coverage effective mass. We have also\nobserved the predicted second layer-state which becomes occupied once the first\nlayer-state density exceeds about 0.6 monolayers.",
        "positive": "A unified theory to describe the transition of stable nanobubbles to\n  unstable microbubbles on homogeneous surface: Experiments have not only revealed the remarkably long lifetime of\nnanobubbles, but also demonstrated the diffusive instability of bubbles above\nmicrometers, thus a full-scale physical understanding on the stability of\nbubbles is in urgent need. Herein, we develop a model that captures the state\ntransition from the stable nanobubbles to the unstable microbubbles on\nhomogeneous surfaces. The transition explains the typical long lifetime,\nlimited height and small contact angle of surface nanobubbles observed in\nexperiments. The consequent phase diagram shows that the bubble size and gas\ndissolving saturation determine the dynamic behaviors of surface bubbles,\nnamely growth, stability, shrinkage or dissolution."
    },
    {
        "anchor": "Electric-Field-Induced Phase Separation and Labyrinthine Patterns in\n  Nanocolloids: In this paper we report universal labyrinthine patterns observed in\nnanocolloids originated from electric-field-induced phase separation. For\nnanocolloids consisting of magnetic particles (magnetic fluids), the\nlabyrinthine pattern as the result of the co-existence of two phases is found\nto be stable against perturbation by an additional magnetic field. The\nrelaxation back to the globally disordered pattern after the magnetic field is\nremoved clearly shows evolution of \"undulation\" thus demonstrates that\nsuperimposing magnetic and electric fields can easily manipulate the patterns\nresulted from the phase separation, indicating that a magnetic fluid has an\nadvantage in exploring the dynamics of defects that has applications in many\nfields.",
        "positive": "Dispersion of activity at an active-passive nematic interface: Efficient nutrient mixing is crucial for the survival of bacterial colonies\nand other living systems. This raises the question of whether the optimization\nof mixing through the emergence of active turbulent motion in bacterial swarms\nplayed a role in the evolution of bacterial shapes. Here, to address this\nquestion, we solve the hydrodynamic equation for active nematics coupled with\nan advection-diffusion equation for the nutrients. The latter models a\nconserved activity field and mimics the conservation of nutrients in bacterial\nswarms. At the interface between active and passive nematic phases, in addition\nto diffusion, the activity is transported by interfacial flows and in turn\nmodifies them through active stresses. We find that the interfacial dispersion\nof the conserved activity is subdiffusive due to the emergence of a barrier of\nnegative defects at the active-passive interface, which hinders the propagation\nof the motile positive defects. Furthermore, we observe a non-monotonic\ndependence of the generalized diffusion coefficient on the aligning parameter,\nwhich is related to the shape of the particles. Our simulations suggest that\nthere is an optimal shape that maximizes the dispersion of conserved activity\nat the active-passive nematic interface."
    },
    {
        "anchor": "Kinetic Transition Networks for the Thomson Problem and Smale's 7th\n  Problem: The Thomson Problem, arrangement of identical charges on the surface of a\nsphere, has found many applications in physics, chemistry and biology. Here we\nshow that the energy landscape of the Thomson Problem for $N$ particles with\n$N=132, 135, 138, 141, 144, 147$ and $150$ is single funnelled, characteristic\nof a structure-seeking organisation where the global minimum is easily\naccessible. Algorithmically constructing starting points close to the global\nminimum of such a potential with spherical constraints is one of Smale's 18\nunsolved problems in mathematics for the 21st century because it is important\nin the solution of univariate and bivariate random polynomial equations. By\nanalysing the kinetic transition networks, we show that a randomly chosen\nminimum is in fact always `close' to the global minimum in terms of the number\nof transition states that separate them, a characteristic of small world\nnetworks.",
        "positive": "Final State Effects in the high q response of $^3$He-$^4$He mixtures: A modified Gersch-Rodriguez formalism describing the leading Final State\nEffects in the high momentum transfer response of low concentration\n$^3$He-$^4$He mixtures is presented and discussed. The leading corrections to\nthe Impulse Approximation are expressed in terms of the interatomic potentials\nand the semidiagonal two-body density matrices of both the mixture and its\nboson-boson approximation, in which the $^3$He atoms are replaced by bosons of\nthe same mass and at the same partial density. Numerical calculations of the\nFinal State Effects functions of $^3$He and $^4$He are finally presented and\ndiscussed."
    },
    {
        "anchor": "Phase behaviour of additive binary mixtures in the limit of infinite\n  asymmetry: We provide an exact mapping between the density functional of a binary\nmixture and that of the effective one-component fluid in the limit of infinite\nasymmetry. The fluid of parallel hard cubes is thus mapped onto that of\nparallel adhesive hard cubes. Its phase behaviour reveals that demixing of a\nvery asymmetric mixture can only occur between a solvent-rich fluid and a\npermeated large particle solid or between two large particle solids with\ndifferent packing fractions. Comparing with hard spheres mixtures we conclude\nthat the phase behaviour of very asymmetric hard-particle mixtures can be\ndetermined from that of the large component interacting via an adhesive-like\npotential.",
        "positive": "Machine learning and predicting the time dependent dynamics of local\n  yielding in dry foams: The yielding of dry foams is enabled by small elementary yield events on the\nbubble scale, \"T1\"s. We study the large scale detection of these in an\nexpanding 2D flow geometry using artificial intelligence (AI) and nearest\nneighbour analysis. A good level of accuracy is reached by the AI approach\nusing only a single frame, with the maximum score for vertex centered images\nhighlighting the important role the vertices play in the local yielding of\nfoams. We study the predictability of T1s ahead of time and show that this is\npossible on a timescale related to the waiting time statistics of T1s in local\nneighborhoods. The local T1 event predictability development is asymmetric in\ntime, and measures the variation of the local property to yielding and\nsimilarly the existence of a relaxation timescale post local yielding."
    },
    {
        "anchor": "Micro helical polymeric structures produced by variable voltage direct\n  electrospinning: Direct near field electrospinning is used to produce very long helical\npolystyrene microfibers in water. The pitch length of helices can be controlled\nby changing the applied voltage, allowing to produce both micro springs and\nmicrochannels. Using a novel high frequency variable voltage electrospinning\nmethod we found the helix formation speed and compared the experimental\nbuckling frequency to theoretical expressions for viscous and elastic buckling.\nFinally we showed that the newmethod can be used to produce new periodic micro\nand nano structures.",
        "positive": "Shape and Chirality Transitions in Off-Axis Twist Nematic Elastomer\n  Ribbons: Using both experiments and finite element simulations, we explore the shape\nevolution of off-axis nematic elastomer ribbons as a function of temperature.\nThe elastomers are prepared by cross-linking the mesogens with planar anchoring\nof the director at top and bottom surfaces with a 90 degree left-handed twist.\nShape evolution depends sensitively on the off-axis director orientation at the\nsample mid-plane. When the director at midplane is parallel to either the\nribbon's long or short axes, ribbons form either helicoids or spirals depending\non the aspect ratio and temperature. If the director at midplane is more than 5\ndegrees off-axis, then they form only spiral ribbons. Samples in all these\ngeometries show a remarkable transition from right- to left-handed chiral\nshapes on change of temperature. Simulation studies provide insight into the\nmechanisms driving shape evolution and enable engineering design of these\nmaterials for future applications."
    },
    {
        "anchor": "Optomechanical conversion by mechanical turbines: Liquid crystal elastomers are rubbers with liquid crystal order. They\ncontract along their nematic director when heated or illuminated. The shape\nchanges are large and occur in a relatively narrow temperature interval, or at\nlow illumination, around the nematic-isotropic transition. We present a\nconceptual design of a mechanical, turbine-based engine using photo-active\nliquid crystal elastomers to extract mechanical work from light. Its efficiency\nis estimated to be 40%.",
        "positive": "Morphology and stability of droplets sliding on soft viscoelastic\n  substrates: We show that energy dissipation partition between a liquid and a solid\ncontrols the shape and stability of droplets sliding on viscoelastic gels. When\nboth phases dissipate energy equally, droplet dynamics is similar to that on\nrigid solids. When only the solid dissipate, we observe an apparent contact\nangle hysteresis, of viscoelastic origin. We find excellent agreement between\nour data and a non-linear model of the wetting of gels of our own that also\nindicates the presence of significant slip. Our work opens general questions on\nthe dynamics of curved contact lines on compliant substrates."
    },
    {
        "anchor": "Quasistatic kinetic avalanches and self-organized criticality in\n  deviatorically loaded granular media: The behavior of granular media under quasi-static loading has recently been\nshown to attain a stable evolution state corresponding to a manifold in the\nspace of micromechanical variables. This state is characterized by sudden\ntransitions between metastable jammed states, involving the partial\nmicromechanical rearrangement of the granular medium. Using numerical\nsimulations of two-dimensional granular media under quasistatic biaxial\ncompression, we show that the dynamics in the stable evolution state is\ncharacterized by scale-free avalanches well before the macromechanical\nstationary flow regime traditionally linked to a self-organized critical state.\nThis, together with the non-uniqueness and the non-monotony of macroscopic\ndeformation curves, suggests that the statistical avalanche properties and the\nsusceptibilities of the system cannot be reduced to a function of the\nmacromechanical state. The associated scaling exponents are non-universal and\ndepend on the interactions between particles. For stiffer particles (or samples\nat low confining pressure) we find distributions of avalanche properties\ncompatible with the predictions of mean-field theory. The scaling exponents\ndecrease below the mean-field values for softer interactions between particles.\nThese lower exponents are consistent with observations for amorphous solids at\ntheir critical point. We specifically discuss the relationship between\nmicroscopic and macroscopic variables, including the relation between the\nexternal stress drop and the internal potential energy released during kinetic\navalanches.",
        "positive": "Molecular packing, hydrogen bonding, and fast dynamics in\n  lysozyme/trehalose/glycerol and trehalose/glycerol glasses at low hydration: Water and glycerol are well-known to facilitate the structural relaxation of\namorphous protein matrices. However, several studies evidenced that they may\nalso limit fast ($\\sim$ pico-nanosecond, ps-ns) and small-amplitude ($\\sim$ \\AA\n) motions of proteins, which govern their stability in freeze-dried sugar\nmixtures. To determine how they interact with proteins and sugars in glassy\nmatrices and, thereby, modulate their fast dynamics, we performed molecular\ndynamics (MD) simulations of lysozyme/trehalose/glycerol (LTG) and\ntrehalose/glycerol (TG) mixtures at low glycerol and water concentrations. Upon\naddition of glycerol and/or water, the glass transition temperature,\nT$_{\\textrm{g}}$, of LTG and TG mixtures decreases, the molecular packing of\nglasses is improved, and the mean-square displacements (MSDs) of lysozyme and\ntrehalose either decrease or increase, depending on the time scale and on the\ntemperature considered. A detailed analysis of the hydrogen bonds (HBs) formed\nbetween species reveals that water and glycerol may antiplasticize the fast\ndynamics of lysozyme and trehalose by increasing the total number and/or the\nstrength of the HBs they form in glassy matrices."
    },
    {
        "anchor": "Drag forces on inclusions in classical fields with dissipative dynamics: We study the drag force on uniformly moving inclusions which interact\nlinearly with dynamical free field theories commonly used to study soft\ncondensed matter systems. Drag forces are shown to be nonlinear functions of\nthe inclusion velocity and depend strongly on the field dynamics. The general\nresults obtained can be used to explain drag forces in Ising systems and also\npredict the existence of drag forces on proteins in membranes due to couplings\nto various physical parameters of the membrane such as composition, phase and\nheight fluctuations.",
        "positive": "Super-stretchable Elastomer from Cross-linked Ring Polymers: The stretchability of polymeric materials is critical to many applications\nsuch as stretchable electronics and soft robotics, yet the stretchability of\nconventional cross-linked linear polymers is limited by the entanglements\nbetween polymer chains. We show using molecular dynamics simulations that\ncross-linked ring polymers are significantly more stretchable than cross-linked\nlinear polymers. Compared to linear polymers, the entanglements between ring\npolymers do not act as effective cross-links. As a result, the stretchability\nof cross-linked ring polymers is determined by the maximum extension of polymer\nstrands between cross-links, rather than between entanglements as in\ncross-linked linear polymers. The more compact conformation of ring polymers\nbefore deformation also contributes to the increase in stretchability."
    },
    {
        "anchor": "Visualization of stacking faults in fcc crystals in plastic deformations: Using molecular dynamics simulation, we investigate the dynamics of stacking\nfaults in fcc crystals in uniaxial stretching in a Lennard-Jones binary mixture\ncomposed of 4096 particles in three dimensions. We visualize stacking faults\nusing a disorder variable $D_j(t)$ for each particle $j$ constructed from local\nbond order parameters based on spherical harmonics (Steinhardt order\nparameters). Also introducing a method of bond breakage, we examine how\nstacking faults are formed and removed by collective particle motions. These\nprocesses are relevant in plasticity of fcc crystals.",
        "positive": "Unsupervised learning for local structure detection in colloidal systems: We introduce a simple, fast, and easy to implement unsupervised learning\nalgorithm for detecting different local environments on a single-particle level\nin colloidal systems. In this algorithm, we use a vector of standard\nbond-orientational order parameters to describe the local environment of each\nparticle. We then use a neural-network-based autoencoder combined with Gaussian\nmixture models in order to autonomously group together similar environments. We\ntest the performance of the method on snapshots of a wide variety of colloidal\nsystems obtained via computer simulations, ranging from simple isotropically\ninteracting systems, to binary mixtures, and even anisotropic hard cubes.\nAdditionally, we look at a variety of common self-assembled situations such as\nfluid-crystal and crystal-crystal coexistences, grain boundaries, and\nnucleation. In all cases, we are able to identify the relevant local\nenvironments to a similar precision as \"standard\", manually-tuned and\nsystem-specific, order parameters. In addition to classifying such\nenvironments, we also use the trained autoencoder in order to determine the\nmost relevant bond orientational order parameters in the systems analyzed."
    },
    {
        "anchor": "Conventional methods fail to measure c_p(omega) of glass-forming liquids: The specific heat is frequency dependent in highly viscous liquids. By\nsolving the full one-dimensional thermo-viscoelastic problem analytically it is\nshown that, because of thermal expansion and the fact that mechanical stresses\nrelax on the same time scale as the enthalpy relaxes, the plane thermal-wave\nmethod does not measure the isobaric frequency-dependent specific heat\nc_p(omega). This method rather measures a \"longitudinal\" frequency-dependent\nspecific heat, a quantity defined and detailed here that is in-between\nc_p(omega) and c_v(omega). This result means that no wide-frequency\nmeasurements of c_p(omega) on liquids approaching the calorimetric glass\ntransition exist. We briefly discuss consequences for experiment.",
        "positive": "Study of the heating effect contribution to the nonlinear dielectric\n  response of a supercooled liquid: We present a detailed study of the heating effects in dielectric measurements\ncarried out on a liquid. Such effects come from the dissipation of the electric\npower in the liquid and give a contribution to the nonlinear third harmonics\nsusceptibility chi_3 which depends on the frequency and temperature. This study\nis used to evaluate a possible `spurious' contribution to the recently measured\nnonlinear susceptibility of an archetypical glassforming liquid (Glycerol).\nThose measurements have been shown to give a direct evaluation of the number of\ndynamically correlated molecules temperature dependence close to the glass\ntransition temperature T_g~190K (Crauste-Thibierge et al., Phys. Rev. Lett\n104,165703(2010)). We show that the heating contribution is totally negligible\n(i) below 204K at any frequency; (ii) for any temperature at the frequency\nwhere the third harmonics response chi_3 is maximum. Besides, this heating\ncontribution does not scale as a function of f/f_{\\alpha}, with f_{\\alpha}(T)\nthe relaxation frequency of the liquid. In the high frequency range, when\nf/f_{\\alpha} >= 1, we find that the heating contribution is damped because the\ndipoles cannot follow instantaneously the temperature modulation due to the\nheating phenomenon. An estimate of the magnitude of this damping is given."
    },
    {
        "anchor": "Impact-induced collapse of an inclined wet granular layer: The collapse of an inclined cohesive granular layer triggered by a certain\nperturbation can be a model for not only landslides on Earth but also\nrelaxations of asteroidal surface terrains. To understand such terrain\ndynamics, we conduct a series of experiments of a solid-projectile impact onto\nan inclined wet granular layer with various water contents and inclination\nangles. As a result, we find two types of outcomes: \"crater formation\" and\n\"collapse\". The \"collapse\" phase is observed when the inclination angle is\nclose to the maximum stable angle and the impact-induced vibration at the\nbottom of wet granular layer is sufficiently strong. To explain the collapse\ncondition, we propose a simple block model considering the maximum stable\nangle, inclination angle, and impact-induced vibrational acceleration.\nAdditionally, the attenuating propagation of the impact-induced vibrational\nacceleration is estimated on the basis of three-dimensional numerical\nsimulations with discrete element method using dry particles. By combining\nwet-granular experiments and dry-granular simulations, we find that the\nimpact-induced acceleration attenuates anisotropically in space. With a help of\nthis attenuation form, the physical conditions to induce the collapse can be\nestimated using the block model.",
        "positive": "Scaling Theory of the Mechanical Properties of Amorphous Nano-Films: Numerical Simulations are employed to create amorphous nano-films of a chosen\nthickness on a crystalline substrate which induces strain on the film. The\nfilms are grown by a vapor deposition technique which was recently developed to\ncreate very stable glassy films. Using the exact relations between the Hessian\nmatrix and the shear and bulk moduli we explore the mechanical properties of\nthe nano-films as a function of the density of the substrate and the film\nthickness. The existence of the substrate dominates the mechanical properties\nof the combined substrate-film system. Scaling concepts are then employed to\nachieve data collapse in a wide range of densities and film thicknesses."
    },
    {
        "anchor": "Polar Nematic Phases with Enantiotropic Ferro- and Antiferroelectric\n  Behavior: The recent discovery of a new ferroelectric nematic (NF) liquid crystalline\nphase became of utmost interest for the liquid crystal (LC) and the whole soft\nand condensed matter fields. Contrary to the previously known ferroelectric LC\nmaterials, whose ferroelectric characteristics were much weaker, new polar\nnematics exhibit properties comparable to solid ferroelectrics. This discovery\nbrought about tremendous efforts to further explore compounds showing these\nphases, and fascinating physical properties have been reported. Herein, we\npresent the first synthesized compounds with the enantiotropic ferro- (NF) and\nantiferroelectric (NX) nematic phases. The enantiotropic nature and an\nunprecedentedly broad temperature range of NF and NX phases are confirmed by\nvarious experimental techniques: polarized-light optical microscopy (POM)\nobservations, different scanning calorimetry (DSC), dielectric spectroscopy,\nsecond harmonic generation (SHG), and molecular modeling. The presented\nachievements in designing achiral compounds that exhibit enantiotropic polar\nnematic phases with ferro- and antiferroelectric properties significantly\ncontribute to the development of multicomponent mixtures with a broad\ntemperature range of NF and NX phases down to room temperature. Furthermore,\nthis accomplishment considerably enhances the general understanding of the\nstructural correlations that promote polar nematic liquid crystal phases with\nhigh thermodynamic stability. Finally, this work may benefit various\napplications in photonic devices.",
        "positive": "Effects of an embedding bulk fluid on phase separation dynamics in a\n  thin liquid film: Using dissipative particle dynamics simulations, we study the effects of an\nembedding bulk fluid on the phase separation dynamics in a thin planar liquid\nfilm. The domain growth exponent is altered from 2D to 3D behavior upon the\naddition of a bulk fluid, even though the phase separation occurs in 2D\ngeometry. Correlated diffusion measurements in the film show that the presence\nof bulk fluid changes the nature of the longitudinal coupling diffusion\ncoefficient from logarithmic to algebraic dependence of 1/s, where s is the\ndistance between the two particles. This result, along with the scaling\nexponents, suggests that the phase separation takes place through the Brownian\ncoagulation process."
    },
    {
        "anchor": "Effective charge versus bare charge for colloids in the infinite\n  dilution limit: We propose an analytical approximation for the dependence of the effective\ncharge on the bare charge for spherical and cylindrical macro-ions as a\nfunction of the size of the colloid and salt content, for the situation of a\nunique colloid immersed in a sea of electrolyte (where the definition of an\neffective charge is non ambiguous).\n  Our approach is based on the Poisson-Boltzmann (PB) mean-field theory.\nMathematically speaking, our estimate is asymptotically exact in the limit\n$\\kappa a\\gg 1$, where $a$ is the radius of the colloid and $\\kappa$ the\ninverse screening length. In practice, a careful comparison with effective\ncharges parameters obtained by numerically solving the full non-linear PB\ntheory proves that it is good down to $\\kappa a\\sim 1$. This is precisely the\nlimit appropriate to treat colloidal suspensions. A particular emphasis is put\non the range of parameters suitable to describe both single and double strand\nDNA molecules under physiological conditions.",
        "positive": "Active hydraulics laws from frustration principles: Viscous flows are laminar and deterministic. Robust linear laws accurately\npredict their streamlines in structures as complex as blood vessels, porous\nmedia and pipe networks. However, biological and synthetic active fluids defy\nthese fundamental laws. Irrespective of their microscopic origin, confined\nactive flows are intrinsically bistable, and therefore non-linear. As a\nconsequence, their emergent patterns in channel networks are out of reach of\navailable theories, and lack quantitative experiments. Here, we lay out the\nbasic laws of active hydraulics. We show that active hydraulic flows are\nnon-deterministic and yield degenerate streamline patterns ruled by frustration\nat nodes with an odd coordination number. More precisely, colloidal-roller\nexperiments in trivalent networks reveal how active-hydraulic flows realize\ndynamical spin ices. The resulting streamline patterns split into two distinct\nclasses of self-similar loops, which reflect the fractionalization of\ntopological defects at the subchannel scales. Informed by our measurements, we\nformulate the laws of active hydraulics as a double spin model. A series of\nmappings on loop O(n) models then allow us to exactly predict the geometry of\nthe degenerate streamlines. We expect our fundamental understanding to provide\nrobust design rules for active microfluidic devices, and to offer unanticipated\navenues to understand the motion of living cells and organisms in complex\nhabitats."
    },
    {
        "anchor": "Growth kinetics of interfacial patterns formed by the radial\n  displacement of an aging viscoelastic suspension: When a soft glassy colloidal suspension is displaced by a Newtonian fluid in\na radial Hele-Shaw geometry, the pattern morphology that develops at the\ninterface is determined by the complex rheology of the former. We had reported\nin an earlier work [Palak, V. R. S. Parmar, D. Saha and R. Bandyopadhyay, JCIS\nOpen, 6 (2022) 100047] that a range of interfacial patterns can be formed by\ncontrolling the elasticity of the displaced suspension, the flow rate of the\ndisplacing fluid and the interfacial tension of the fluid pair. Interestingly,\nall the different morphological features can be distinguished in terms of their\nareal ratios, defined as the ratio of the areas occupied by the fully-developed\npattern and the smallest circle enclosing it. In a significant advance to this\nearlier work, we show here that a systematic study of spatio-temporal pattern\ngrowth can reveal important information about pattern selection mechanisms. We\nanalyse the time-evolution of the patterns to reveal interesting correlations\nbetween their growth mechanisms and fully-developed morphologies. We believe\nthat such systematic identification of the unique temporal features\ncharacterising pattern growth at the interface between an aging viscoelastic\nclay suspension and a Newtonian fluid can be useful in predicting and\nsuppressing the onset and evolution of interfacial instabilities in the\ndisplacement of mud and cement slurries.",
        "positive": "Dielectric study on mixtures of ionic liquids: Ionic liquids are promising candidates for electrolytes in energy-storage\nsystems. We demonstrate that mixing two ionic liquids allows to precisely tune\ntheir physical properties, like the dc conductivity. Moreover, these mixtures\nenable the gradual modification of the fragility parameter, which is believed\nto be a measure of the complexity of the energy landscape in supercooled\nliquids. The physical origin of this index is still under debate; therefore,\nmixing ionic liquids can provide further insights. From the chemical point of\nview, tuning ionic liquids via mixing is an easy and thus an economic way. For\nthis study, we performed detailed investigations by broadband dielectric\nspectroscopy and differential scanning calorimetry on two mixing series of\nionic liquids. One series combines an imidazole based with a pyridine based\nionic liquid and the other two different anions in an imidazole based ionic\nliquid. The analysis of the glass-transition temperatures and the thorough\nevaluations of the measured dielectric permittivity and conductivity spectra\nreveal that the dynamics in mixtures of ionic liquids are well defined by the\nfractions of their parent compounds."
    },
    {
        "anchor": "Differential orientation and conformation of Keratinocyte Growth Factor\n  observed at HEMA, HEMA/MMA, and HEMA/MAA hydrogel surfaces developed for\n  wound healing: The development of hydrogels for protein delivery requires protein-hydrogel\ninteractions that cause minimal disruption of the protein's biological\nactivity. Biological activity can be influenced by factors such as orientation\nand conformation. Hydrogels must promote the adsorption of biomolecules onto\nthe surface and the diffusion of biomolecules into the porous network at the\nsurface, while maintaining native protein conformation, keeping the protein in\nan accessible orientation for receptor binding, and maximizing protein release.\nWe report here the evaluation of (hydroxyethyl)methacrylate (HEMA)-based\nhydrogel systems for the delivery of keratinocyte growth factor (KGF) to\npromote re-epithelialization in wound healing. In this work, we characterize\ntwo hydrogel blends in addition to HEMA alone, and report how protein\norientation, conformation, and protein release is affected. The first blend\nincorporates methyl methacrylate (MMA), which is known to promote adsorption of\nprotein to its surface due to its hydrophobicity. The second blend incorporates\nmethacrylic acid (MAA), which is known to promote the diffusion of protein into\nits surface due to its hydrophilicity. We find that KGF at the surface of the\nHEMA/MMA blend appears to be more orientationally accessible and\nconformationally active than KGF at the surface of the HEMA/MAA blend. We also\nreport that KGF at the surface of the HEMA/MAA blend becomes conformationally\ndenatured, likely due to hydrogen bonding. While KGF at the surface of these\nblends can be differentiated by FTIR-ATR spectroscopy and ToF-SIMS in\nconjunction with PCA, KGF swelling, uptake, and release profiles are\nindistinguishable. The differences in KGF orientation and conformation between\nthese blends may result in different biological responses in future cell-based\nexperiments.",
        "positive": "Time scales of inertial motion in the collective dynamics of underdamped\n  active phase field crystal systems: Many active matter systems, mostly on the microscopic scale, are well\napproximated as overdamped, meaning that any inertial momentum is immediately\ndissipated by the environment. On the other hand, especially for macroscopic\nactive systems but also for many mesoscopic ones the time scale of inertial\nmotion can become large enough to be relevant for the dynamics. This raises the\nquestion how collective dynamics in active matter is influenced by inertia. In\nthis article we implement and study an underdamped active phase field crystal\nmodel. We focus on how the collective dynamics changes with the time scale of\ninertial motion. While the state diagram stays unaltered in this modification,\nthe relaxation time scale towards the steady state considerably increases with\nparticle mass. Our numerical results suggest that transiently stable rotating\nclusters of density peaks act as defects which need to decay before the final\nstate of global collective motion forms. We extract the formation and decay\ntimes quantitatively. Finally, we give a physical intuition for the formation\nand decay of rotating clusters to qualitatively explain how the extracted times\ndepend on mass."
    },
    {
        "anchor": "Continuum Percolation of Polydisperse Rods in Quadrupole Fields: Theory\n  and Simulations: We investigate percolation in mixtures of nanorods in the presence of\nexternal fields that align or disalign the particles with the field axis. Such\nconditions are found in the formulation and processing of nanocomposites, where\nthe field may be electric, magnetic, or due to elongational flow. Our focus is\non the effect of length polydispersity, which -- in the absence of a field --\nis known to produce a percolation threshold that scales with the inverse weight\naverage of the particle length. Using a model of non-interacting\nspherocylinders in conjunction with connectedness percolation theory, we show\nthat a quadrupolar field always increases the percolation threshold and that\nthe universal scaling with the inverse weight average no longer holds if the\nfield couples to the particle length. Instead, the percolation threshold\nbecomes a function of higher moments of the length distribution, where the\norder of the relevant moments crucially depends on the strength and type of\nfield applied. The theoretical predictions compare well with the results of our\nMonte Carlo simulations, which eliminate finite size effects by exploiting the\nfact that the universal scaling of the wrapping probability function holds even\nin anisotropic systems. Theory and simulation demonstrate that the percolation\nthreshold of a polydisperse mixture can be lower than that of the individual\ncomponents, confirming recent work based on a mapping onto a Bethe lattice as\nwell as earlier computer simulations involving dipole fields. Our work shows\nhow the formulation of nanocomposites may be used to compensate for the adverse\neffects of aligning fields that are inevitable under practical manufacturing\nconditions.",
        "positive": "Thermal effects on nonlinear acceleration waves in the Biot theory of\n  porous media: We generalize a theory of Biot for a porous solid based on nonlinear\nelasticity theory to incorporate temperature effects. Acceleration waves are\nstudied in detail in the fully nonlinear theory. The wavespeeds are found\nexplicitly and the amplitudes are then determined. The possibility of shock\nformation is discussed."
    },
    {
        "anchor": "Modeling microscopic swimmers at low Reynolds number: We employ three numerical methods to explore the motion of low Reynolds\nnumber swimmers, modeling the hydrodynamic interactions by means of the Oseen\ntensor approximation, lattice Boltzmann simulations and multiparticle collision\ndynamics. By applying the methods to a three bead linear swimmer, for which\nexact results are known, we are able to compare and assess the effectiveness of\nthe different approaches. We then propose a new class of low Reynolds number\nswimmers, generalized three bead swimmers that can change both the length of\ntheir arms and the angle between them. Hence we suggest a design for a\nmicrostructure capable of moving in three dimensions. We discuss multiple bead,\nlinear microstructures and show that they are highly efficient swimmers. We\nthen turn to consider the swimming motion of elastic filaments. Using\nmultiparticle collision dynamics we show that a driven filament behaves in a\nqualitatively similar way to the micron-scale swimming device recently\ndemonstrated by Dreyfus et al.",
        "positive": "Controlled self-assembly of periodic and aperiodic cluster crystals: Soft particles are known to overlap and form stable clusters that\nself-assemble into periodic crystalline phases with density-independent lattice\nconstants. We use molecular dynamics simulations in two dimensions to\ndemonstrate that, through a judicious design of an isotropic pair potential,\none can control the ordering of the clusters and generate a variety of phases,\nincluding decagonal and dodecagonal quasicrystals. Our results confirm\nanalytical predictions based on a mean-field approximation, providing insight\ninto the stabilization of quasicrystals in soft macromolecular systems, and\nsuggesting a practical approach for their controlled self-assembly in\nlaboratory realizations using synthesized soft-matter particles."
    },
    {
        "anchor": "Experimental Realization of the Green-Kubo Relation in Colloidal\n  Suspensions Enabled by Image-based Stress Measurements: By combining confocal microscopy and Stress Assessment from Local Structural\nAnisotropy (SALSA), we directly measure stresses in 3D quiescent colloidal\nliquids. Our non-invasive and non-perturbative method allows us to measure\nforces $\\lesssim$ 50 fN with a small and tunable probing volume, enabling us to\nresolve the stress fluctuations arising from particle thermal motions. We use\nthe Green-Kubo relation to relate these measured stress fluctuations to the\nbulk Brownian viscosity at different volume fractions and comparing against\nsimulations and conventional rheometry measurements. We demonstrate that the\nGreen-Kubo analysis gives excellent agreement with these prior results. This\nagreement provides a strong demonstration of the applicability of the\nGreen-Kubo relation in nearly hard-sphere suspensions and opens the door to\ninvestigations of local flow properties in many poorly understood\nfar-from-equilibrium systems, including suspensions that are glassy,\nstrongly-sheared, or highly-confined.",
        "positive": "Slow dynamics of a colloidal lamellar phase: We used x-ray photon correlation spectroscopy to study the dynamics in the\nlamellar phase of a platelet suspension as a function of the particle\nconcentration. We measured the collective diffusion coefficient along the\ndirector of the phase, over length scales down to the interparticle distance,\nand quantified the hydrodynamic interaction between the particles. This\ninteraction sets in with increasing concentration and can be described\nqualitatively by a simplified model. No change in the microscopic structure or\ndynamics is observed at the transition between the fluid and the gel-like\nlamellar phases."
    },
    {
        "anchor": "CO$_2$-driven diffusiophoresis for removal of bacteria: We investigate CO$_2$-driven diffusiophoresis of colloidal particles and\nbacterial cells in a Hele-Shaw geometry. Combining experiments and a model, we\nunderstand the characteristic length and time scales of CO$_2$-driven\ndiffusiophoresis in relation to system dimensions and CO$_2$ diffusivity.\nDirectional migration of wild-type V. cholerae and a mutant lacking flagella,\nas well as S. aureus and P. aeruginosa, near a dissolving CO$_2$ source shows\nthat diffusiophoresis of bacteria is achieved independent of cell shape and\nGram stain. Long-time experiments suggest possible applications for bacterial\ndiffusiophoresis to cleaning systems or anti-biofouling surfaces.",
        "positive": "Colloidal aggregation and critical Casimir forces - Reply: In a recent Letter [Phys. Rev. Lett. 103, 156101 (2009)], we presented\nexperiments on critical Casimir induced colloidal aggregation in a system with\nnegligibly small van der Waals forces. We presented a simple model based on a\ncompetition between repulsive electrostatic and attractive critical Casimir\nforces to account for the observed aggregation. A recent comment [A. Gambassi,\nS. Dietrich, arXiv:1006.5897v1] proposed that the simple model should be\nregarded with caution as to its domain of application, and that it can be\nrefined in a number of different ways. Here, we revisit our experimental\nfinding and give a reply to the comment."
    },
    {
        "anchor": "Nanodroplets on rough hydrophilic and hydrophobic surfaces: We present results of Molecular Dynamics (MD) calculations on the behavior of\nliquid nanodroplets on rough hydrophobic and hydrophilic solid surfaces. On\nhydrophobic surfaces, the contact angle for nanodroplets depends strongly on\nthe root mean square roughness amplitude, but it is nearly independent of the\nfractal dimension of the surface. Since increasing the fractal dimension\nincreases the short-wavelength roughness, while the long-wavelength roughness\nis almost unchanged, we conclude that for hydrophobic interactions the\nshort-wavelength (atomistic) roughness is not very important. We show that the\nnanodroplet is in a Cassie-like state. For rough hydrophobic surfaces, there is\nno contact angle hysteresis due to strong thermal fluctuations, which occur at\nthe liquid-solid interface on the nanoscale. On hydrophilic surfaces, however,\nthere is strong contact angle hysteresis due to higher energy barrier. These\nfindings may be very important for the development of artificially biomimetic\nsuperhydrophobic surfaces.",
        "positive": "Effects of particles on spinodal decomposition: A Phase field study: In this thesis, we study the interplay of phase separation and wetting in\nmulticomponent systems. For this purpose, we have examined the phase separation\npattern of a binary mixture (AB) in presence of stationary spherical particles\n(C) which prefers one of the components of the binary (say, A). Binary AB is\ncomposed of critical composition(50:50) and off-critical compositions(60:40,\n40:60). Particle sizes of 8 units and 16 units are used in the simulations. Two\ntypes of particle loading are used, 5\\% and 10\\%. We have employed a ternary\nform of Cahn-Hilliard equation to incorporate immobile fillers in our system.\nTo elucidate the effect of wetting on phase separation we have designed three\nsets of $\\chi_{ij}$ and $\\kappa_{ij}$ to include the effects of neutral\npreference, weak preference and strong preference of the particle for one of\nthe binary components. If the particles are preferentially wetted by one of the\ncomponents then early stage microstructures show transient concentric alternate\nlayers of preferred and non-preferred phases around the particles. When\nparticles are neutral to binary components then such a ring pattern does not\nform. At late times, neutral preference between particles and binary components\nyields a continuous morphology whereas preferential wetting produces isolated\ndomains of non-preferred phases dispersed in a continuous matrix of preferred\nphase. For off-critical compositions, if minor component wets the particle then\na bicontinuous morphology results whereas if major component wets the network a\ndroplet morphology is seen. When majority component wets the particle, a\npossibility of double phase separation is reported. In such alloys phase\nseparation starts near the particle surface and propagates to the bulk at\nintermediate to late times forming spherical or nearly spherical droplets of\nthe minor component."
    },
    {
        "anchor": "Nucleation and growth in one dimension, part I: The generalized\n  Kolmogorov-Johnson-Mehl-Avrami model: Motivated by a recent application of the Kolmogorov-Johnson-Mehl-Avrami\n(KJMA) model to the study of DNA replication, we consider the one-dimensional\nversion of this model. We generalize previous work to the case where the\nnucleation rate is an arbitrary function $I(t)$ and obtain analytical results\nfor the time-dependent distributions of various quantities (such as the island\ndistribution). We also present improved computer simulation algorithms to study\nthe 1D KJMA model. The analytical results and simulations are in excellent\nagreement.",
        "positive": "3D polymer simulations of genome organization and transcription across\n  different chromosomes and cell types: We employ the diffusing transcription factors model for numerical simulation\nof chromatin topology conformations and transcriptional processes of human\nchromatin. Simulations of a short chromatin filament reveal different possible\npathways to regulate transcription: it is shown that the transcriptional\nactivity profile can be regulated and controlled by either acting on the chain\nstructural properties, or on external factors, such as the number of\ntranscription factors. Additionally, comparisons between GRO-seq experimental\ndata and large scale numerical simulation of entire chromosomes from the human\numbilical vein endothelial cell and the B-lmphocyte GM12878 show that the model\nprovides reliable and statistically significant predictions for transcription\nacross different cell-lines."
    },
    {
        "anchor": "Fermi-Bose quantum degenerate ^40 K - ^87 Rb mixture with attractive\n  interaction: We report on the achievement of simultaneous quantum degeneracy in a mixed\ngas of fermionic ^40 K and bosonic ^87 Rb. Potassium is cooled to 0.3 times the\nFermi temperature by means of an efficient thermalization with evaporatively\ncooled rubidium. Direct measurement of the collisional cross-section confirms a\nlarge interspecies attraction. This interaction is shown to affect the\nexpansion of the Bose-Einstein condensate released form the magnetic trap,\nwhere it is immersed in the Fermi sea.",
        "positive": "Ductile and brittle yielding in thermal and athermal amorphous materials: We study theoretically the yielding of sheared amorphous materials as a\nfunction of increasing levels of initial sample annealing prior to shear, in\nthree widely used constitutive models and three widely studied annealing\nprotocols. In thermal systems we find a gradual progression, with increasing\nannealing, from smoothly \"ductile\" yielding, in which the sample remains\nhomogeneous, to abruptly \"brittle\" yielding, in which it becomes strongly shear\nbanded. This progression arises from an increase with annealing in the size of\nan overshoot in the underlying stress-strain curve for homogeneous shear, which\ncauses a shear banding instability that becomes more severe with increasing\nannealing. \"Ductile\" and \"brittle\" yielding thereby emerge as two limiting\ncases of a continuum of yielding transitions, from gradual to catastrophic. In\ncontrast, athermal systems with a stress overshoot always show brittle yielding\nat low shear rates, however small the overshoot."
    },
    {
        "anchor": "Growth kinetics of NaCl crystals in a drying drop of gelatin: transition\n  from faceted to dendritic growth: We report a study on the kinetics of drying of a droplet of aqueous gelatin\ncontaining sodium chloride. The process of drying recorded on video, clearly\nshows different regimes of growth leading to a variety of crystalline patterns.\nLarge faceted crystals of $\\sim$mm size form in the early stages of\nevaporation, followed by highly branched multi-fractal patterns with micron\nsized features. We simulate the growth using a simple algorithm incorporating\naggregation and evaporation, which reproduces the cross-over between the two\ngrowth regimes. As evaporation proceeds, voids form in the gel film. The time\ndevelopment of the fluid-void system can be characterized by an Euler number. A\nminimum in the Euler number marks the transition between the two regimes of\ngrowth.",
        "positive": "How to measure work functions from aqueous solutions: The recent application of concepts from condensed-matter physics to\nphotoelectron spectroscopy (PES) of volatile, liquid-phase systems has enabled\nthe measurement of electronic energetics of liquids on an absolute scale.\nParticularly, vertical ionization energies, VIEs, of liquid water and aqueous\nsolutions, both in the bulk and at associated interfaces, can now be routinely\ndetermined. These IEs are referenced to the local vacuum level, which is the\nappropriate quantity for condensed matter with associated surfaces, including\nliquids. Here, we connect this newly accessible energy level to another\nimportant surface property, namely, the solution work function, e$\\Phi_{liq}$.\nWe lay out the prerequisites for and unique challenges of determining e$\\Phi$\nof aqueous solutions and liquids in general. We demonstrate - for a model\naqueous solution with a tetra-n-butylammonium iodide (TBAI) surfactant solute -\nthat concentration-dependent work functions, associated with the surface\ndipoles generated by the segregated interfacial layer of TBA$^+$ and I$^-$ions,\ncan be accurately measured under controlled conditions. We detail the nature of\nsurface potentials, uniquely tied to the nature of the flowing-liquid sample,\nwhich must be eliminated or quantified to enable such measurements. This allows\nus to refer measured spectra of aqueous solutions to the Fermi level and\nquantitatively assign surfactant concentration-dependent spectral shifts to\ncompeting work function and electronic-structure effects, the latter\ndetermining, e.g., (electro)chemical reactivity. We describe the extension of\nliquid-jet PES to quantitatively access concentration-dependent surface\ndescriptors that have so far been restricted to solid-phase measurements. These\nstudies thus mark the beginning of a new era in the characterization of the\ninterfacial electronic structure of aqueous solutions and liquids more\ngenerally."
    },
    {
        "anchor": "On self similarity and coarsening rate of a convecting bicontinuous\n  phase separating mixture: effect of the viscosity contrast: We present a computational study of the hydrodynamic coarsening in 3D of a\ncritical mixture using the Cahn-Hilliard/Navier-Stokes model. The topology of\nthe resulting intricate bicontinuous microstructure is analyzed through the\nprincipal curvatures to prove self-similar morphological evolution. We find\nthat the self similarity exists for both systems: iso-viscous and with variable\nviscosity. However the two system have distinct topological character. Our\nsimulations confirm that the predicted viscous growth regime exists in both\ncases. Moreover the coarsening rate is inversely proportional to an\n\\textit{effective viscosity} that is the geometrical average of the viscosities\nof the two phases.",
        "positive": "Frustration and Packing in Curved-Filament Assemblies: From Isometric to\n  Isomorphic Bundles: Densely-packed bundles of biological filaments (filamentous proteins) are\ncommon and critical structural elements in range of biological materials. While\nmost bundles form from intrinsically straight filaments, there are notable\nexamples of protein filaments possessing a natural, or intrinsic, curvature,\nsuch as the helical bacterial flagellum. We study the non-linear interplay\nbetween thermodynamic preference for dense and regular inter-filament packing\nand the mechanical preference for uniform filament shape in bundles of\nhelically-curved filaments. Geometric constraints in bundles make perfect\ninter-filament (constant spacing, or isometric) packing incompatible with\nperfect intra-filament (constant shape, or isomorphic) packing. As a\nconsequence, we predict that bundle packing exhibits a strong sensitivity to\nbundle size, evolving from the isometric packing at small radii to an\nisomorphic packing at large radii. The nature of the transition between these\nextremal states depends on thermodynamic costs of packing distortion, with\npacking in elastically-constrained bundles evolving smoothly with size, while\npacking in osmotically-compressed bundles may exhibit a singular transition\nfrom the isometric packing at a finite bundle radius. We consider the\nequilibrium assembly of bundles in a saturated solution of filaments and show\nthat mechanical cost of isomorphic packing leads to self-limited equilibrium\nbundle diameters, whose size and range of thermodynamic stability depend both\non condensation mechanism, as well as the helical geometry of filaments."
    },
    {
        "anchor": "Investigation of Galilean Invariance of multi-phase lattice Boltzmann\n  methods: We examine the Galilean invariance of standard lattice Boltzmann methods for\ntwo-phase fluids. We show that the known Galilean invariant term that is cubic\nin the velocities, and is usually neglected, is the main source of Galilean\ninvariance violations. We show that incorporating a correction term can improve\nthe Galilean invariance of the method by up to an order of magnitude.\nSurprisingly incorporating this correction term can also noticeably increase\nthe range of stability for multi-phase algorithms. We found that this is true\nfor methods in which the non-ideality is incorporated by a forcing term as well\nas methods in which non-ideality is directly incorporated in a non-ideal\npressure tensor.",
        "positive": "Pair-Variational Autoencoders (PairVAE) for Linking and\n  Cross-Reconstruction of Characterization Data from Complementary Structural\n  Characterization Techniques: In material research, structural characterization often requires multiple\ncomplementary techniques to obtain a holistic morphological view of the\nsynthesized material. Depending on the availability of and accessibility of the\ndifferent characterization techniques (e.g., scattering, microscopy,\nspectroscopy), each research facility or academic research lab may have access\nto high-throughput capability in one technique but face limitations (sample\npreparation, resolution, access time) with other techniques(s). Furthermore,\none type of structural characterization data may be easier to interpret than\nanother (e.g., microscopy images are easier to interpret than small angle\nscattering profiles). Thus, it is useful to have machine learning models that\ncan be trained on paired structural characterization data from multiple\ntechniques so that the model can generate one set of characterization data from\nthe other. In this paper we demonstrate one such machine learning workflow,\nPairVAE, that works with data from Small Angle X-Ray Scattering (SAXS) that\npresents information about bulk morphology and images from Scanning Electron\nMicroscopy (SEM) that presents two-dimensional local structural information of\nthe sample. Using paired SAXS and SEM data of novel block copolymer assembled\nmorphologies [open access data from Doerk G.S., et al. Science Advances. 2023\nJan 13;9(2): eadd3687], we train our PairVAE. After successful training, we\ndemonstrate that the PairVAE can generate SEM images of the block copolymer\nmorphology when it takes as input that sample's corresponding SAXS 2D pattern,\nand vice versa. This method can be extended to other soft materials\nmorphologies as well and serves as a valuable tool for easy interpretation of\n2D SAXS patterns as well as creating a database for other downstream\ncalculations of structure-property relationships."
    },
    {
        "anchor": "A mean field thermodynamic framework for time dependent self-assembly\n  and pattern formation: In this work, we use a minimal model to introduce a framework for controlling\nself-assembly under the influence of time-dependent driving forces. We develop\na mean-field thermodynamic framework that predicts the conditions required to\nreliably self-assemble a desired spatial pattern under time-varying external\nfields. We also calculate the entropy production associated with the\ntime-dependent self-assembly process and examine how it can be used to predict\nconditions under which the external time-varying signal is reliably encoded as\na spatial pattern in the self-assembling material. While the results in this\nwork are developed in the context of a minimal one-dimensional model, we\nanticipate that the framework can be used to establish guidelines for\ncontrolling self-assembly in more complex scenarios.",
        "positive": "Soft macromolecular confinement: We study equilibrium shapes and shape transformations of a confined\nsemiflexible chain inside a soft lipid tubule using simulations and continuum\ntheories. The deformed tubular shapes and chain conformations depend on the\nrelative magnitude of their bending moduli. We characterise the collapsed\nmacromolecular shapes by computing statistical quantities that probe the\npolymer properties at small length scales and report a prolate to toroidal coil\ntransition for stiff chains. Deformed tubular shapes, calculated using elastic\ntheories, agree with simulations. In conjunction with scattering studies, our\nwork may provide a mechanistic understanding of gene encapsulation in soft\nstructures."
    },
    {
        "anchor": "Condensates of Strongly-interacting Atoms and Dynamically Generated\n  Dimers: In a system of atoms with large positive scattering length, weakly-bound\ndiatomic molecules (dimers) are generated dynamically by the strong\ninteractions between the atoms. If the atoms are modeled by a quantum field\ntheory with an atom field only, condensates of dimers cannot be described by\nthe mean-field approximation because there is no field associated with the\ndimers. We develop a method for describing dimer condensates in such a model\nbased on the one-particle-irreducible (1PI) effective action. We construct an\nequivalent 1PI effective action that depends not only on the classical atom\nfield but also on a classical dimer field. The method is illustrated by\napplying it to the many-body behavior of bosonic atoms with large scattering\nlength at zero temperature using an approximation in which the 2-atom amplitude\nis treated exactly but irreducible $N$-atom amplitudes for $N \\ge 3$ are\nneglected. The two 1PI effective actions give identical results for the atom\nsuperfluid phase, but the one with a classical dimer field is much more\nconvenient for describing the dimer superfluid phase. The results are also\ncompared with previous work on the Bose gas near a Feshbach resonance.",
        "positive": "Unique dynamic crossover in supercooled x,3-dihydroxypropyl acrylate (x\n  = 1, 2) isomers mixture: The previtreous dynamics in glass forming monomer, glycerol monoacrylate\n(GMA), using broadband dielectric spectroscopy (BDS) was tested. Measurements\nrevealed the clear dynamic crossover at temperature $T_B = 254$ K and the time\nscale $\\tau(T_B) = 5.4$ ns for the primary (structural) relaxation time and no\nhallmarks for the crossover for the DC electric conductivity $\\sigma_{DC}$.\nThis result was revealed via the derivative-based and distortions-sensitive\nanalysis $dln{H_{a}}/d(1/T)$ vs. $1/T$, where $H_a$ is for the apparent\nactivation energy. Subsequent tests of the fractional Debye-Stokes-Einsten\nrelation $\\sigma_{DC}(\\tau_{\\alpha})^S = const$ showed that the crossover is\nassociated with $S = 1$ (for $T>T_B$)->$S = 0.84$ (for $T<T_B$). The crossover\nis associated with the emergence of the secondary beta relaxation which\nsmoothly develops deeply into the solid amorphous phase below the glass\ntemperature $T_g$."
    },
    {
        "anchor": "Dynamics of nanodroplets on topographically structured substrates: Mesoscopic hydrodynamic equations are solved to investigate the dynamics of\nnanodroplets positioned near a topographic step of the supporting substrate.\nOur results show that the dynamics depends on the characteristic length scales\nof the system given by the height of the step and the size of the nanodroplets\nas well as on the constituting substances of both the nanodroplets and the\nsubstrate. The lateral motion of nanodroplets far from the step can be\ndescribed well in terms of a power law of the distance from the step. In\ngeneral the direction of the motion depends on the details of the effective\nlaterally varying intermolecular forces. But for nanodroplets positioned far\nfrom the step it is solely given by the sign of the Hamaker constant of the\nsystem. Moreover, our study reveals that the steps always act as a barrier for\ntransporting liquid droplets from one side of the step to the other.",
        "positive": "Integrated photoelasticity in a soft material: phase retardation,\n  azimuthal angle and stress-optic coefficient: Integrated photoelasticity is investigated for a soft material subjected to a\nthree-dimensional stress state. In the experiment, a solid sphere is pressed\nagainst a gelatin gel (Young's modulus is about 4.2 kPa) that deforms up to 4.5\nmm depending on the loading forces. The resulting photoelastic parameters\n(phase retardation, azimuthal angle, and stress-optic coefficient) in the gel\nare measured using a polarization camera. The measured retardation and azimuth\nare compared with the analytical prediction based on Hertzian contact theory.\nRemarkably, experimental and analytical results of the photoelastic parameters\nshow a reasonable agreement not only in the retardation but also in the azimuth\nthat is related to the direction of principal stresses and but rarely validated\nin previous studies, is essential for reconstructing three-dimensional stress\nfields in soft materials. The stress-optic coefficient of the gelatin gel used\nis 3.12$\\times10^{-8}$ 1/Pa. Such findings proved that integrated\nphotoelasticity is useful for measuring the three-dimensional stress field in\nsoft materials, which is of importance in biomedical engineering and cell\nprinting applications."
    },
    {
        "anchor": "Natural selection in the colloid world: Active chiral spirals: We present a model system in which to study natural selection in the colloid\nworld. In the assembly of active Janus particles into rotating pinwheels when\nmixed with trace amounts of homogeneous colloids in the presence of an AC\nelectric field, broken symmetry in the rotation direction produces spiral,\nchiral shapes. Locked into a central rotation point by the center particle, the\nspiral arms are found to trail rotation of the overall cluster. To achieve a\nsteady state, the spiral arms undergo an evolutionary process to coordinate\ntheir motion. Because all the particles as segments of the pinwheel arms are\nself-propelled, asymmetric arm lengths are tolerated. Reconfiguration of these\nstructures can happen in various ways and various mechanisms of this directed\nstructural change are analyzed in detail. We introduce the concept of VIP (very\nimportant particles) to express that sustainability of active structures is\nmost sensitive to only a few particles at strategic locations in the moving\nself-assembled structures.",
        "positive": "Enhanced stability of layered phases in parallel hard-spherocylinders\n  due to the addition of hard spheres: There is increasing evidence that entropy can induce microphase separation in\nbinary fluid mixtures interacting through hard particle potentials. One such\nphase consists of alternating two dimensional liquid-like layers of rods and\nspheres. We study the transition from a uniform miscible state to this ordered\nstate using computer simulations and compare results to experiments and theory.\nWe conclude that (1) there is stable entropy driven microphase separation in\nmixtures of parallel rods and spheres, (2) adding spheres smaller then the rod\nlength decreases the total volume fraction needed for the formation of a\nlayered phase, therefore small spheres effectively stabilize the layered phase;\nthe opposite is true for large spheres and (3) the degree of this stabilization\nincreases with increasing rod length."
    },
    {
        "anchor": "Spontaneous deformation and fission of oil droplets on an aqueous\n  surfactant solution: We investigated the spontaneous deformation and fission of a tetradecane\ndroplet containing palmitic acid (PA) on a stearyltrimethylammonium chloride\n(STAC) aqueous solution. In this system, the generation and rupture of the gel\nlayer composed of PA and STAC induce the droplet deformation and fission.To\ninvestigate the characteristics of the droplet-fission dynamics, we obtained\nthe time series of the number of the droplets, and confirmed that the number\nhas a peak at a certain STAC concentration. Since the fission of the droplet\nshould be led by the deformation, we analyzed four parameters which may relate\nto the fission dynamics from the spatio-temporal correlation of the\ndroplet-boundary velocity. As a result, we found that the faster deformation\nwould be the key factor for the fission dynamics.",
        "positive": "Dynamics of Three-Dimensional Vesicles in DC Electric fields: A numerical and systematic parameter study of three-dimensional vesicle\nelectrohydrodynamics is presented to investigate the effects of different fluid\nand membrane properties. The dynamics of vesicles in the presence of DC\nelectric fields is considered, both in the presence and absence of linear shear\nflow. For suspended vesicles it is shown that the conductivity ratio and\nviscosity ratio between the interior and exterior fluids, as well as the\nvesicle membrane capacitance, substantially affect the minimum electric field\nstrength required to induce a full Prolate-Oblate-Prolate transition.In\naddition, there exists a critical electric field strength above which a vesicle\nwill no longer tumble when exposed to linear shear flow."
    },
    {
        "anchor": "Structure of poly(propyl ether imine) (PETIM) dendrimer from fully\n  atomistic molecular Dynamics Simulation and by Small Angle X-ray scattering: We study the structure of carboxylic acid terminated neutral poly (propyl\nether imine) (PETIM) dendrimer from generation 1 through 6 (G1-G6) in a good\nsolvent (water) by fully atomistic molecular dynamics (MD) simulations. We\ndetermine as a function of generation such structural properties as: radius of\ngyration, shape tensor, asphericity, fractal dimension, monomer density\ndistribution, and end-group distribution functions. The sizes obtained from the\nMD simulations have been validated by Small Angle X-Ray Scattering (SAXS)\nexperiment on dendrimer of generation 2 to 4 (G2-G4). A good agreement between\nthe experimental and theoretical value of radius of gyration has been observed.\nWe find a linear increase in radius of gyration with the generation. In\ncontrast, Rg scales as ~ N^x with the number of monomers. We find two distinct\nexponents depending on the generations: x = 0.47 for G1-G3 and x = 0.28 for\nG3-G6 which reveals their non-space filling nature. In comparison with the\namine terminated PAMAM dendrimer, we find Rg of G-th generation PETIM dendrimer\nis nearly equal to that of (G+1)-th generation of PAMAM dendrimer as observed\nby Maiti et. al. [Macromolecules,38, 979 2005]. We find substantial back\nfolding of the outer sub generations into the interior of the dendrimer. Due to\ntheir highly flexible nature of the repeating branch units, the shape of the\nPETIM dendrimer deviates significantly from the spherical shape and the\nmolecules become more and more spherical as the generation increases. The\ninterior of the dendrimer is quite open with internal cavities available for\naccommodating guest molecules suggesting using PETIM dendrimer for guest-host\napplications. We also give a quantitative measure of the number of water\nmolecules present inside the dendrimer.",
        "positive": "From discrete elements to continuum fields: Extension to bidisperse\n  systems: To develop, calibrate and/or validate continuum models from experimental or\nnumerical data, micro-macro transition methods are required. These methods are\nused to obtain the continuum fields (such as density, momentum, stress) from\nthe discrete data (positions, velocities, forces). This is especially\nchallenging for non-uniform and dynamic situations in the presence of multiple\ncomponents. Here, we present a general method to perform this micro-macro\ntransition, but for simplicity we restrict our attention to two-component\nscenarios, e.g. particulate mixtures containing two types of particles. We\npresent an extension to the micro-macro transition method, called\n\\emph{coarse-graining}, for unsteady two-component flows. By construction, this\nnovel averaging method is advantageous, e.g. when compared to binning methods,\nbecause the obtained macroscopic fields are consistent with the continuum\nequations of mass, momentum, and energy balance. Additionally, boundary\ninteraction forces can be taken into account in a self-consistent way and thus\nallow for the construction of continuous stress fields even within one particle\nradius of the boundaries. Similarly, stress and drag forces can also be\ndetermined for individual constituents of a multi-component mixture, which is\nessential for several continuum applications, \\textit{e.g.} mixture theory\nsegregation models. Moreover, the method does not require ensemble-averaging\nand thus can be efficiently exploited to investigate static, steady, and\ntime-dependent flows. The method presented in this paper is valid for any\ndiscrete data, \\textit{e.g.} particle simulations, molecular dynamics,\nexperimental data, etc."
    },
    {
        "anchor": "Closed-form solutions for continuous time random walks on finite chains: Continuous time random walks (CTRW) on finite arbitrarily inhomogeneous\nchains are studied. By introducing a technique of counting all possible\ntrajectories, we derive closed-form solutions in Laplace space for the Green's\nfunction and for the first passage time probability density function (PDF) for\nnearest neighbor CTRWs in terms of the input waiting time PDFs. These solutions\nare also the Laplace space solutions of the generalized master equation (GME).\nMoreover, based on our counting technique, we introduce the adaptor function\nfor expressing higher order propagators (joint PDFs of time-position variables)\nfor CTRWs in terms of Green's functions. Using the derived formulae, an escape\nproblem from a biased chain is considered.",
        "positive": "Mesostructured composite materials with electrically tunable\n  upconversion properties: A promising approach of designing mesostructured materials with novel\nphysical behavior is to combine unique optical and electronic properties of\nsolid nanoparticles with long-range ordering and facile response of soft matter\nto weak external stimuli. Here we design, practically realize, and characterize\norientationally ordered nematic liquid crystalline dispersions of rod-like\nupconversion nanoparticles. Boundary conditions on particle surfaces, defined\nthrough surface functionalization, promote spontaneous unidirectional\nself-alignment of the dispersed rod-like nanoparticles, mechanically coupled to\nthe molecular ordering direction of the thermotropic nematic liquid crystal\nhost. As host is electrically switched at low voltages~ 1V, nanorods rotate,\nyielding tunable upconversion and polarized luminescence properties of the\ncomposite. We characterize spectral and polarization dependencies, explain them\nthrough invoking models of electrical switching and upconversion dependence on\ncrystalline matrices of nanorods, and discuss potential practical uses."
    },
    {
        "anchor": "Spatiotemporal analysis of nonaffine displacements in disordered solids\n  sheared across the yielding point: The time evolution and spatial correlations of nonaffine displacements in\ndeformed amorphous solids are investigated using molecular dynamics\nsimulations. The three-dimensional model glass is represented via the binary\nmixture, which is slowly annealed well below the glass transition temperature\nand then sheared at a constant strain rate. It is shown that with increasing\nstrain, the typical size of clusters of atoms with large nonaffine\ndisplacements increases, and these clusters remain spatially homogeneously\ndistributed, until the yielding point when mobile atoms become localized within\na system-spanning shear band. Furthermore, the yielding transition is\nassociated with an abrupt change in the spatial correlation of nonaffine\ndisplacements, which varies from exponential to power-law decay. We also find\nthat the height of the first peak in the pair correlation function of small\natoms exhibits a distinct increase at the yielding strain. These results are\ndiscussed in relation to the yielding transition in amorphous materials under\ncyclic loading.",
        "positive": "Heterogeneous dynamics during yielding of glasses: effect of aging: Molecular dynamics computer simulations of a binary Lennard-Jones glass under\nshear are presented. The mechanical response of glassy states having different\nthermal histories is investigated by imposing a wide range of external shear\nrates, at different temperatures. The stress-strain relations exhibit an\novershoot at a strain of around 0.1, marking the yielding of the glass sample\nand the onset of plastic flow. The amplitude of the overshoot shows a\nlogarithmic behavior with respect to a dimensionless variable, given by the age\nof the sample times the shear rate. Dynamical heterogeneities having finite\nlifetimes, in the form of shear bands, are observed as the glass deforms under\nshear. By quantifying the spatial fluctuations of particle mobility, we\ndemonstrate that such shearbanding occurs only under specific combinations of\nimposed shear-rate, age of glass and ambient temperature."
    },
    {
        "anchor": "Translational invariance of Coulomb series and symmetric potentials in\n  crystals: It is shown that Coulomb series are to be considered within a special mode of\nsummation so as to describe bulk properties of crystals. The translational\ninvariance is then an explicit integral property of Coulomb series that is\ntantamount to the effect of invariant periodic boundary conditions discussed\nearlier. Absolute bulk potentials with zero mean value are then substantiated\nas a unique solution in the general case of triclinic lattices. An invariant\ntreatment of the bulk Coulomb energy follows therefrom. The potential symmetry\nis verified for simple point-charge lattices and is connected with the centre\nof gravity of the potential field that is relevant to non-local charges as\nwell.",
        "positive": "Screening properties of Gaussian electrolyte models, with application to\n  dissipative particle dynamics: We investigate the screening properties of Gaussian charge models of\nelectrolyte solutions by analysing the asymptotic behaviour of the pair\ndistribution functions. We use a combination of Monte-Carlo simulations with\nthe hyper-netted chain integral equation closure, and the random phase\napproximation, to establish the conditions under which a screening length is\nwell defined and the extent to which it matches the expected Debye length. For\npractical applications, for example in dissipative particle dynamics, we are\nable to summarise our results in succinct rules-of-thumb which can be used for\nmesoscale modeling of electrolyte solutions. We thereby establish a solid\nfoundation for future work, such as the systematic incorporation of specific\nion effects."
    },
    {
        "anchor": "Statistics and Geometrical Picture of Ring Polymer Melts and Solutions: We present a detailed account of a recently proposed phenomenological theory\nfor noncatenated ring polymer melts (Phys. Rev. Lett. 106, 167802 (2011)). A\nbasic assumption lies in the implementation of the noncatenation constraint via\nthe effective excluded-volume effect, from which a geometrical picture of melts\nemerges. The result captures many of the salient features observed so far,\nincluding (i) the overall spacial size of rings, (ii) the coordinate number,\ni.e., the number of rings surrounding a given ring, (iii) the topological\nlength scale as a function of the molecular weight and (iv) the effect of the\nchain stiffness and concentration. We also suggest a geometrical interpretation\nof the topological length scale, which may shed some light on the entanglement\nconcept in polymeric systems.",
        "positive": "Formation of the Smectic-B Crystal from a Simple Monatomic Liquid: We report a molecular dynamics simulation demonstrating that the Smectic B\ncrystalline phase (Cr-B), commonly observed in mesogenic systems of anisotropic\nmolecules, can be formed by a system of identical particles interacting via a\nspherically symmetric potential. The Cr-B phase forms as a result of a first\norder transition from an isotropic liquid phase upon isochoric cooling at\nappropriate number density. Its structure, determined by the design of the pair\npotential corresponds to Cr-B structure formed by elongated particles with the\naspect ratio 1.8. The diffraction pattern, and the real-space structure\ninspection demonstrate dominance of the ABC-type of axial layer stacking. This\nresult opens a general possibility of producing smectic phases using isotropic\ninterparticle interaction both in simulations and in colloidal systems."
    },
    {
        "anchor": "Boundary of two mixed Bose-Einstein condensates: The boundary of two mixed Bose-Einstein condensates interacting repulsively\nwas considered in the case of spatial separation at zero temperature.\nAnalytical expressions for density distribution of condensates were obtained by\nsolving two coupled nonlinear Gross-Pitaevskii equations in cases corresponding\nweak and strong separation. These expressions allow to consider excitation\nspectrum of a particle confined in the vicinity of the boundary as well as\nsurface waves associated with surface tension.",
        "positive": "Entropic Unmixing in Nematic Blends of Semiflexible Polymers: Binary mixtures of semiflexible polymers with the same chain length but\ndifferent persistence lengths separate into two coexisting different nematic\nphases when the osmotic pressure of the lyotropic solution is varied. Molecular\nDynamics simulations and Density Functional Theory predict phase diagrams\neither with a triple point, where the isotropic phase coexists with two nematic\nphases, or a critical point of unmixing within the nematic mixture. The\ndifference in locally preferred bond angles between the constituents drives\nthis unmixing without any attractive interactions between monomers."
    },
    {
        "anchor": "Relation between local density and density relaxation near glass\n  transition in a glass forming binary mixture: Many investigations shed light on various correlations between structure and\ndynamics in supercooled liquids; however, a general relation between structure\nand dynamics remains elusive. This molecular dynamics simulation study\nidentifies the interrelationship between the growth of the highest peak of the\nradial distribution function, variation in the radial force from this peak, and\nthe slowdown of the density relaxation in the supercooled states of a model\nbinary glass former. From the microscopic string-like motion in supercooled\nliquids, we argue that the surface density on a spherical shell around a\nreference particle at the highest peak of the radial distribution function can\nrepresent the free volume available for motion. We further show from these\narguments and simulations that density relaxtion time and local density are\nconnected; in this expression, the dynamics diverge at a higher critical value\nof local density. This relation is similar to the Vogel Fulcher Tammann\nrelation in supercooled liquids, thus giving insight into the structural origin\nof the VFT as the jamming of particles in a channel of density relaxation.",
        "positive": "Ionic liquids confined in 1D CNT membranes:gigantic ionic conductivity: Ionic Liquids (ILs) are organic molten salts characterized by the total\nabsence of solvent. They show remarkable properties: low vapor pressure, high\nionic conductivity, high chemical, thermal and electrochemical stability. These\nelectrolytes meet therefore key criteria for the development of safe energy\nstorage systems. Due to a competition between electrostatic and van der Walls\ninteractions, ILs show an uncommon property for neat bulk liquids: they\nself-organize in transient nanometric domains. In ILs-based electrochemical\ndevices, this fluctuating nano-segregation acts as energy barriers to the long\nrange diffusional processes and hence to the ionic conductivity. Here, we show\nhow the ionic conductivity of ILs can be increased by more than one order of\nmagnitude by exploiting one dimensional (1D) confinement effects in\nmacroscopically oriented carbon nanotube (CNT) membranes. We identify 1D CNT\nmembranes as promising separators for high instant power batteries."
    },
    {
        "anchor": "Relative phase fluctuations of two coupled one-dimensional condensates: We study the relative phase fluctuations of two one-dimensional condensates\ncoupled along their whole extension with a local single-atom interaction. The\nthermal equilibrium is defined by the competition between independent\nlongitudinal thermally excited phase fluctuations and the coupling between the\ncondensates which locally favors identical phase. We compute the relative phase\nfluctuations and their correlation length as a function of the temperature and\nthe strength of the coupling.",
        "positive": "Nonlinear master relation in microscopic mechanical response of\n  semiflexible biopolymer networks: A network of semiflexible biopolymers, known as the cytoskeleton, and\nmolecular motors play fundamental mechanical roles in cellular activities. The\ncytoskeletal response to forces generated by molecular motors is profoundly\nlinked to physiological processes. However, owing to the highly nonlinear\nmechanical properties, the cytoskeletal response on the microscopic level is\nlargely elusive. The aim of this study is to investigate the microscopic\nmechanical response of semiflexible biopolymer networks by conducting\nmicrorheology (MR) experiments. Micrometer-sized colloidal particles, embedded\nin semiflexible biopolymer networks, were forced beyond the linear regime at a\nvariety of conditions by using feedback-controlled optical trapping. This\nhigh-bandwidth MR technology revealed an affine elastic response, which showed\nstiffening upon local forcing. After scaling the stiffening behaviors, with\nparameters describing semi-flexible networks, a collapse onto a single master\ncurve was observed. The physics underlying the general microscopic response is\npresented to justify the collapse, and its potentials/implications to elucidate\ncell mechanics is discussed."
    },
    {
        "anchor": "Dynamic and Facilitated Binding of Topoisomerase Accelerates Topological\n  Relaxation: How type 2 Topoisomerase (TopoII) proteins relax and simplify the topology of\nDNA molecules is one of the most intriguing open questions in biophysics. Most\nof the existing models neglect the dynamics of TopoII which is characteristics\nfor proteins searching their targets via facilitated diffusion. Here, we show\nthat dynamic binding of TopoII speeds up the topological relaxation of knotted\nsubstrates by enhancing the search of the knotted arc. Intriguingly, this in\nturn implies that the timescale of topological relaxation is virtually\nindependent of the substrate length. We then discover that considering binding\nbiases due to facilitated diffusion on looped substrates steers the sampling of\nthe topological space closer to the boundaries between different topoisomers\nyielding an optimally fast topological relaxation. We discuss our findings in\nthe context of topological simplification in vitro and in vivo.",
        "positive": "Nanoparticle Taylor dispersion near charged surfaces with an open\n  boundary: The dispersive spreading of microscopic particles in shear flows is\ninfluenced both by advection and thermal motion. At the nanoscale, interactions\nbetween such particles and their confining boundaries become unavoidable. We\naddress the roles of electrostatic repulsion and absorption on the spatial\ndistribution and dispersion of charged nanoparticles in near-surface shear\nflows, observed under evanescent illumination. The electrostatic repulsion\nbetween particles and the lower charged surface is tuned by varying electrolyte\nconcentrations. Particles leaving the field of vision can be neglected from\nfurther analysis, such that the experimental ensemble is equivalent to that of\nTaylor dispersion with absorption. These two ingredients modify the particle\ndistribution, deviating strongly from the Gibbs-Boltzmann one at the nanoscale\nstudied here. The overall effect is to restrain the accessible space available\nto particles, leading to a striking, ten-fold reduction in the spreading\ndynamics as compared to the non-interacting case."
    },
    {
        "anchor": "Electro-Mechanical Fredericks Effects in Nematic Gels: The solid nematic equivalent of the Fredericks transition is found to depend\non a critical field rather than a critical voltage as in the classical case.\nThis arises because director anchoring is principally to the solid rubbery\nmatrix of the nematic gel rather than to the sample surfaces. Moreover, above\nthe threshold field, we find a competition between quartic (soft) and\nconventional harmonic elasticity which dictates the director response. By\nincluding a small degree of initial director misorientation, the calculated\nfield variation of optical anisotropy agrees well with the conoscopy\nmeasurements of Chang et al (Phys.Rev.E56, 595, 1997) of the electro-optical\nresponse of nematic gels.",
        "positive": "Simulating isothermal aging of snow: A Monte Carlo algorithm to simulate the isothermal recrystallization process\nof snow is presented. The snow metamorphism is approximated by two mass\nredistribution processes, surface diffusion and sublimation-deposition. The\nalgorithm is justified and its parametrization is determined. The simulation\nresults are compared to experimental data, in particular, the temporal\nevolution of the specific surface area and the ice thickness. We find that the\ntwo effects of surface diffusion and sublimation-deposition can accurately\nmodel many aspects of the isothermal metamorphism of snow. Furthermore, it is\nshown that sublimation-deposition is the dominant contribution for temperatures\nclose to the melting point, whereas surface diffusion dominates at temperatures\nfar below the melting point. A simple approximation of gravitational compaction\nis implemented to simulate density change."
    },
    {
        "anchor": "Irreversible hardening of a colloidal gel under shear: the smart\n  response of natural rubber latex gels: Natural rubber is obtained by processing natural rubber latex, a liquid\ncolloidal suspension that rapidly gels after exudation from the tree. We\nprepared such gels by acidification, in a large range of particle volume\nfractions, and investigated their rheological properties. We show that natural\nrubber latex gels exhibit a unique behavior of irreversible strain hardening:\nwhen subjected to a large enough strain, the elastic modulus increases\nirreversibly. Hardening proceeds over a large range of deformations in such a\nway that the material maintains an elastic modulus close to, or slightly higher\nthan the imposed shear stress. Local displacements inside the gel are\ninvestigated by ultrasound imaging coupled to oscillatory rheometry, together\nwith a Fourier decomposition of the oscillatory response of the material during\nhardening. Our observations suggest that hardening is associated with\nirreversible local rearrangements of the fractal structure, which occur\nhomogeneously throughout the sample.",
        "positive": "Escape time, relaxation and sticky states of a softened Henon-Heiles\n  model: low-frequency vibrational modes effects: Here we study the relaxation of a chain consisting of 3 masses joined by\nnon-linear springs and periodic conditions when the stiffness is weakened. This\nsystem, when expressed in their normal coordinates, yields a softened\nHenon-Heiles system. By reducing the stiffness of one low-frequency vibrational\nmode, a faster relaxation is enabeled. This is due to a reduction of the energy\nbarrier heights along the softened normal mode as well as for a widening of the\nopening channels of the energy landscape in configurational space. The\nrelaxation is for the most part exponential, and can be explained by a simple\nflux equation. Yet, for some initial conditions the relaxation follows as a\npower law and, and in many cases, there is a regime change from exponential to\npower law decay. We pin point the initial conditions for the power law decay,\nfinding two regions of sticky states. For such states, quasiperiodic orbits are\nfound since almost for all components of the initial momentum orientation, the\nsystem is trapped inside two pockets of configurational space. The softened\nHenon- Heiles model presented here is intended as the simplest model in order\nto understand the interplay of rigidity, non-linear interactions and relaxation\nfor non-equilibrium systems like glass-forming melts or soft-matter."
    },
    {
        "anchor": "Free energies, vacancy concentrations and density distribution\n  anisotropies in hard--sphere crystals: A combined density functional and\n  simulation study: We perform a comparative study of the free energies and the density\ndistributions in hard sphere crystals using Monte Carlo simulations and density\nfunctional theory (employing Fundamental Measure functionals). Using a recently\nintroduced technique (Schilling and Schmid, J. Chem. Phys 131, 231102 (2009))\nwe obtain crystal free energies to a high precision. The free energies from\nFundamental Measure theory are in good agreement with the simulation results\nand demonstrate the applicability of these functionals to the treatment of\nother problems involving crystallization. The agreement between FMT and\nsimulations on the level of the free energies is also reflected in the density\ndistributions around single lattice sites. Overall, the peak widths and\nanisotropy signs for different lattice directions agree, however, it is found\nthat Fundamental Measure theory gives slightly narrower peaks with more\nanisotropy than seen in the simulations. Among the three types of Fundamental\nMeasure functionals studied, only the White Bear II functional (Hansen-Goos and\nRoth, J. Phys.: Condens. Matter 18, 8413 (2006)) exhibits sensible results for\nthe equilibrium vacancy concentration and a physical behavior of the chemical\npotential in crystals constrained by a fixed vacancy concentration.",
        "positive": "Loading-unloading hysteresis loop of randomly rough adhesive contacts: In this paper we investigate the loading and unloading behavior of soft\nsolids in adhesive contact with randomly rough profiles. The roughness is\nassumed to be described by a self-affine fractal on a limited range of\nwave-vectors. A spectral method is exploited to generate such randomly rough\nsurfaces. The results are statistically averaged, and the calculated contact\narea and applied load are shown as a function of the penetration, for loading\nand unloading conditions. We found that the combination of adhesion forces and\nroughness leads to a hysteresis loading-unloading loop. This shows that energy\ncan be lost simply as a consequence of roughness and van der Waals forces, as\nin this case a large number of local energy minima exist and the system may be\ntrapped in metastable states. We numerically quantify the hysteretic loss and\nassess the influence of the surface statistical properties and the energy of\nadhesion on the hysteresis process."
    },
    {
        "anchor": "Fluctuations and Pattern Formation in Fluids with Competing Interactions: One of the most interesting phenomena in the soft-matter realm consists in\nthe spontaneous formation of super-molecular structures (microphases) in\ncondition of thermodynamic equilibrium. A simple mechanism responsible for this\nself-organization or pattern formation is based on the competition between\nattractive and repulsive forces with different length scales in the microscopic\npotential, typically, a short-range attraction against a longer-range\nrepulsion.\n  We analyse this problem by simulations in 2D fluids. We find that, as the\ntemperature is lowered, liquid-vapor phase separation is inhibited by the\ncompetition between attraction and repulsion, and replaced by a transition to\nnon-homogeneous phases. The structure of the fluid shows well defined\nsignatures of the presence of both intra- and inter-cluster correlations.\n  Even when the competition between attraction and repulsion is not so strong\nas to cause microphase formation, it still induces large density fluctuations\nin a wide region of the temperature-density plane. In this large-fluctuation\nregime, pattern formation can be triggered by a weak external modulating field.",
        "positive": "Impact of size polydispersity on the nature of Lennard-Jones liquids: Polydisperse fluids are encountered everywhere in biological and industrial\nprocesses. These fluids naturally show a rich phenomenology exhibiting\nfractionation and shifts in critical point and freezing temperatures. Here, we\nstudy the impact of size polydispersity on the basic nature of Lennard-Jones\n(LJ) liquids, which represent most molecular liquids without hydrogen bonds,\nvia two- and three-dimensional molecular dynamics computer simulations. A\nsingle-component liquid constituting spherical particles and interacting via\nthe LJ potential is known to exhibit strong correlations between virial and\npotential energy equilibrium fluctuations at constant volume. This correlation\nsignificantly simplifies the physical description of the liquid, and these\nliquids are now known as Roskilde-simple (RS) liquids. We show that this simple\nnature of the single-component LJ liquid is preserved even for very high\npolydispersities (above 40% polydispersity for the studied uniform\ndistribution). We also investigate isomorphs of moderately polydisperse LJ\nliquids. Isomorphs are curves in the phase diagram of RS liquids along which\nstructure, dynamics, and some thermodynamic quantities are invariant in\ndimensionless units. We find that isomorphs are a good approximation even for\npolydisperse LJ liquids. The theory of isomorphs thus extends readily to\nmulti-component systems and can be used to improve even further the\nunderstanding of these intriguing systems."
    },
    {
        "anchor": "Rectification of energy and motion in non-equilibrium parity violating\n  metamaterials: Uncovering new mechanisms for rectification of stochastic fluctuations has\nbeen a longstanding problem in non-equilibrium statistical mechanics. Here,\nusing a model parity violating metamaterial that is allowed to interact with a\nbath of active energy consuming particles, we uncover new mechanisms for\nrectification of energy and motion. Our model active metamaterial can generate\nenergy flows through an object in the absence of any temperature gradient. The\nnonreciprocal microscopic fluctuations responsible for generating the energy\nflows can further be used to power locomotion in, or exert forces on, a viscous\nfluid. Taken together, our analytical and numerical results elucidate how the\ngeometry and inter-particle interactions of the parity violating material can\ncouple with the non-equilibrium fluctuations of an active bath and enable\nrectification of energy and motion.",
        "positive": "Jamming II: Edwards' statistical mechanics of random packings of hard\n  spheres: The problem of finding the most efficient way to pack spheres has an\nillustrious history, dating back to the crystalline arrays conjectured by\nKepler and the random geometries explored by Bernal in the 60's. This problem\nfinds applications spanning from the mathematician's pencil, the processing of\ngranular materials, the jamming and glass transitions, all the way to fruit\npacking in every grocery. There are presently numerous experiments showing that\nthe loosest way to pack spheres gives a density of ~55% (RLP) while filling all\nthe loose voids results in a maximum density of ~63-64% (RCP). While those\nvalues seem robustly true, to this date there is no physical explanation or\ntheoretical prediction for them. Here we show that random packings of\nmonodisperse hard spheres in 3d can pack between the densities 4/(4 + 2 \\sqrt\n3) or 53.6% and 6/(6 + 2 \\sqrt 3) or 63.4%, defining RLP and RCP, respectively.\nThe reason for these limits arises from a statistical picture of jammed states\nin which the RCP can be interpreted as the ground state of the ensemble of\njammed matter with zero compactivity, while the RLP arises in the infinite\ncompactivity limit. We combine an extended statistical mechanics approach 'a la\nEdwards' (where the role traditionally played by the energy and temperature in\nthermal systems is substituted by the volume and compactivity) with a\nconstraint on mechanical stability imposed by the isostatic condition.\nUltimately, our results lead to a phase diagram that provides a unifying view\nof the disordered hard sphere packing problem."
    },
    {
        "anchor": "Mesoscale modelling of polyelectrolyte electrophoresis: The electrophoretic behaviour of flexible polyelectrolyte chains ranging from\nsingle monomers up to long fragments of hundred repeat units is studied by a\nmesoscopic simulation approach. Abstracting from the atomistic details of the\npolyelectrolyte and the fluid, a coarse-grained molecular dynamics model\nconnected to a mesoscopic fluid described by the Lattice Boltzmann approach is\nused to investigate free-solution electrophoresis. Our study demonstrates the\nimportance of hydrodynamic interactions for the electrophoretic motion of\npolyelectrolytes and quantifies the influence of surrounding ions. The\nlength-dependence of the electrophoretic mobility can be understood by\nevaluating the scaling behavior of the effective charge and the effective\nfriction. The perfect agreement of our results with experimental measurements\nshows that all chemical details and fluid structure can be safely neglected,\nand a suitable coarse-grained approach can yield an accurate description of the\nphysics of the problem, provided that electrostatic and hydrodynamic\ninteractions between all entities in the system, i.e., the polyelectrolyte,\ndissociated counterions, additional salt and the solvent, are properly\naccounted for. Our model is able to bridge the single molecule regime of a few\nnm up to macromolecules with contour lengths of more than 100 nm, a length\nscale that is currently not accessible to atomistic simulations.",
        "positive": "Rheology of protein-stabilised emulsion gels envisioned as composite\n  networks. 2 -- Framework for the study of emulsion gels: The aggregation of protein-stabilised emulsions leads to the formation of\nemulsion gels. These soft solids are classically envisioned as droplet-filled\nmatrices. Here however, it is assumed that protein-coated sub-micron droplets\ncontribute to the network formation in a similar way to proteins. Emulsion gels\nare thus envisioned as composite networks made of proteins and droplets.\nEmulsion gels with a wide range of composition are prepared and their\nviscoelasticity and frequency dependence are measured. Their rheological\nbehaviours are then analysed and compared with the properties of pure gels\npresented in the first part of this study. The rheological behaviour of\nemulsion gels is shown to depend mostly on the total volume fraction, while the\ncomposition of the gel indicates its level of similarity with either pure\ndroplet gels or pure protein gels. These results converge to form an emerging\npicture of protein-stabilised emulsion gel as intermediate between droplet and\nprotein gels. This justifies a posteriori the hypothesis of composite networks,\nand opens the road for the formulation of emulsion gels with fine-tuned\nrheology."
    },
    {
        "anchor": "Clustering transitions in vibro-fluidized magnetized granular materials: We study the effects of long range interactions on the phases observed in\ncohesive granular materials. At high vibration amplitudes, a gas of magnetized\nparticles is observed with velocity distributions similar to non-magnetized\nparticles. Below a transition temperature compact clusters are observed to form\nand coexist with single particles. The cluster growth rate is consistent with a\nclassical nucleation process. However, the temperature of the particles in the\nclusters is significantly lower than the surrounding gas, indicating a\nbreakdown of equipartition. If the system is quenched to low temperatures, a\nmeta-stable network of connected chains self-assemble due to the anisotropic\nnature of magnetic interactions between particles.",
        "positive": "Tagged-particle motion of Percus-Yevick hard spheres from first\n  principles: We develop a first-principles-based generalized mode-coupling theory (GMCT)\nfor the tagged-particle motion of glassy systems. This theory establishes a\nhierarchy of coupled integro-differential equations for self-multi-point\ndensity correlation functions, which can formally be extended up to infinite\norder. We use our GMCT framework to calculate the self-nonergodicity parameters\nand the self-intermediate scattering function for the Percus-Yevick hard sphere\nsystem, based on the first few levels of the GMCT hierarchy. We also test the\nscaling laws in the $\\alpha$- and $\\beta$-relaxation regimes near the\nglass-transition singularity. Furthermore, we study the mean-square\ndisplacement and the Stoke-Einstein relation in the supercooled regime. We find\nthat qualitatively our GMCT results share many similarities with the\nwell-established predictions from standard mode-coupling theory, but the\nquantitative results change, and typically improve, by increasing the GMCT\nclosure level. However, we also demonstrate on general theoretical grounds that\nthe current GMCT framework is unable to account for violation of the\nStokes-Einstein relation, underlining the need for further improvements in the\nfirst-principles description of glassy dynamics."
    },
    {
        "anchor": "Rigidity of thermalized soft repulsive spheres around the jamming point: We study the effect of thermalization on the rigidity of a randomly packed\nsoft repulsive sphere system around the jamming point by analyzing the\nshear-modulus using the cloned liquid theory with the 1 step replica symmetry\nbreaking ansatz and molecular dynamics simulations. Contrarily to the usual\nharmonic picture for solids, we found that the thermalized jamming system is\nanomalously softer than at zero temperature such that the shear-modulus becomes\nas small as the pressure down to vanishingly low temperatures.",
        "positive": "A \"morphogenetic action\" principle for 3D shape formation by the growth\n  of thin sheets: How does growth encode form in developing organisms? Many different\nspatiotemporal growth profiles may sculpt tissues into the same target 3D\nshapes, but only specific growth patterns are observed in animal and plant\ndevelopment. In particular, growth profiles may differ in their degree of\nspatial variation and growth anisotropy, however, the criteria that distinguish\nobserved patterns of growth from other possible alternatives are not\nunderstood. Here we exploit the mathematical formalism of quasiconformal\ntransformations to formulate the problem of \"growth pattern selection\"\nquantitatively in the context of 3D shape formation by growing 2D epithelial\nsheets. We propose that nature settles on growth patterns that are the\n'simplest' in a certain way. Specifically, we demonstrate that growth pattern\nselection can be formulated as an optimization problem and solved for the\ntrajectories that minimize spatiotemporal variation in areal growth rates and\ndeformation anisotropy. The result is a complete prediction for the growth of\nthe surface, including not only a set of intermediate shapes, but also a\nprediction for cell displacement along those surfaces in the process of growth.\nOptimization of growth trajectories for both idealized surfaces and those\nobserved in nature show that relative growth rates can be uniformized at the\ncost of introducing anisotropy. Minimizing the variation of programmed growth\nrates can therefore be viewed as a generic mechanism for growth pattern\nselection and may help to understand the prevalence of anisotropy in\ndevelopmental programs."
    },
    {
        "anchor": "Salt-specific effects in lysozyme solutions: The effects of additions of low-molecular-mass salts on the properties of\naqueous lysozyme solutions are examined by using the cloud-point temperature,\n$T_{cloud}$, measurements. Mixtures of protein, buffer, and simple salt in\nwater are studied at pH=6.8 (phosphate buffer) and pH=4.6 (acetate buffer). We\nshow that an addition of buffer in the amount above $I_{buffer} = 0.6$ mol\ndm$^{-3}$ does not affect the $T_{cloud}$ values. However, by replacing a\ncertain amount of the buffer electrolyte by another salt, keeping the total\nionic strength constant, we can significantly change the cloud-point\ntemperature. All the salts de-stabilize the solution and the magnitude of the\neffect depends on the nature of the salt. Experimental results are analyzed\nwithin the framework of the one-component model, which treats the\nprotein-protein interaction as highly directional and of short-range. We use\nthis approach to predict the second virial coefficients, and liquid-liquid\nphase diagrams under conditions, where $T_{cloud}$ is determined\nexperimentally.",
        "positive": "Anomaly of the dielectric function of water under confinement and its\n  role in Van der Waals interactions: We present a theoretical calculation of the changes in the Hamaker constant\ndue to the anomalous reduction of the static dielectric function of water.\nUnder confinement, the dielectric function of water decreases from a bulk value\nof 79 down to 2. If the confining walls are made of a dielectric material, the\nHamaker constant reduces almost by 90\\%. However, if the confinement is\nrealized with metallic plates, there is little change in the Hamaker constant.\nAdditionally, we show that confinement can be used to decreases the Debye\nscreening length without changing the salt concentration. This, in turn, is\nused to change the Hamaker constant in the presence of electrolytes."
    },
    {
        "anchor": "Ion size effect on electrostatic and electroosmotic properties in soft\n  nanochannels with pH-dependent charge density: We report a theoretical study of ion size effect on various properties in a\nsoft nanochannel with pH-dependent charge density. We develop a free energy\nbased mean-field theory taking into account ion size as well as pH-dependence\nof charged polyelectrolyte layer grafted on a rigid surface in an electrolyte.\nThe influence of ion size on properties in a soft nanochannel is evaluated by\nnumerically calculating ion number densities and electrostatic potential. We\ndemonstrate that unlike in point-like ions, for finite sizes of ions, a uniform\ndistribution of chargeable sites within the polyelectrolyte layer causes\nunphysical discontinuities in ion number densities not only for hydrogen ion\nbut also for other kinds of ions. It is shown that the same cubic spatial\ndistribution of chargeable sites as for point-like ions is necessary to ensure\ncontinuity of ion number density and zero ion transport at the polyelectrolyte\nlayer - rigid solid interface. We find that considering finite ion size causes\nan increase in electrostatic potential and electroosmotic velocity and a\ndecrease in ion number densities. More importantly, we demonstrate that in\npolyelectrolyte layer, pH-dependence of polyelectrolyte charge density makes\naccumulation of hydrogen ions stronger than for the other positive ion species\nin the electrolyte and such a tendency is further enhanced by considering\nfinite ion size. In addition, we discuss how consideration of finite ion size\naffects the role of various parameters on electrostatic and electroosmotic\nproperties.",
        "positive": "Considerations about universality in phase-ordering of binary liquids: In this article we show that the phase-ordering scaling state for binary\nfluids is not necessarily unique and that local correlations in the initial\nconditions can be responsible for selecting the scaling state. We describe a\nnew scaling state for symmetric volume fractions that consists of drops of the\none component suspended in a matrix of the other. The underlying reason for the\nexistence of the newly observed scaling state is that the main coarsening\nmechanism of binary fluids which is the deformation of interfaces by flow is\nnot acting, and this leads to a new scaling law. An initial droplet state can\nbe formed by a number of physical phenomena. In a unified description this can\nbe undestood as local correlations in the initial conditions. Local\ncorrelations with length $\\xi$ are believed to be irrelevant when the typical\nlength scale L of the system is large ($L\\gg \\xi$). Our result shows that these\ninitial correlations, contrary to current thinking, can be important even at\nlate times."
    },
    {
        "anchor": "Ionic Coulomb blockade as a fractional Wien effect: Recent advances in nanofluidics have allowed exploration of ion transport\ndown to molecular scale confinement, yet artificial porins are still far from\nreaching the advanced functionalities of biological ion machinery. Achieving\nsingle ion transport that is tuneable by an external gate -- the ionic analogue\nof electronic Coulomb blockade (CB) -- would open new avenues in this quest.\nHowever, an understanding of ionic CB beyond the electronic analogy is still\nlacking. Here we show that the many-body dynamics of ions in a charged\nnanochannel result in a quantised and strongly nonlinear ionic transport, in\nfull agreement with molecular simulations. We find that ionic CB occurs when,\nupon sufficient confinement, oppositely charged ions form 'Bjerrum pairs', and\nthe conduction proceeds through a mechanism reminiscent of Onsager's Wien\neffect. Our findings open the way to novel nanofluidic functionalities, such as\nan ionic-CB-based ion pump inspired by its electronic counterpart.",
        "positive": "Twist-bend instability for toroidal DNA condensates: We propose that semiflexible polymers in poor solvent collapse in two stages.\nThe first stage is the well known formation of a dense toroidal aggregate.\nHowever, if the solvent is sufficiently poor, the condensate will undergo a\nsecond structural transition to a twisted entangled state, in which individual\nfilaments lower their bending energy by additionally orbiting around the mean\npath along which they wind. This ``topological ripening'' is consistent with\nknown simulations and experimental results. It connects and rationalizes\nvarious experimental observations ranging from strong DNA entanglement in viral\ncapsids to the unusually short pitch of the cholesteric phase of DNA in\nsperm-heads. We propose that topological ripening of DNA toroids could improve\nthe efficiency and stability of gene delivery."
    },
    {
        "anchor": "Nematic order condensation and topological defects in inertial active\n  nematics: Living materials at different length scales manifest active nematic features\nsuch as orientational order, nematic topological defects, and active nematic\nturbulence. Using numerical simulations we investigate the impact of fluid\ninertia on the collective pattern formation in active nematics. We show that an\nincremental increase in inertial effects due to reduced viscosity results in\ngradual melting of nematic order with an increase in topological defect density\nbefore a discontinuous transition to a vortex-condensate state. The emergent\nvortex-condensate state at low enough viscosities coincides with nematic order\ncondensation within the giant vortices and the drop in the density of\ntopological defects. We further show flow field around topological defects is\nsubstantially affected by inertial effects. Moreover, we demonstrate the strong\ndependence of the kinetic energy spectrum on the inertial effects, recover the\nKolmogorov scaling within the vortex-condensate phase, but find no evidence of\nuniversal scaling at higher viscosities. The findings reveal new complexities\nin active nematic turbulence and emphasize the important cross-talk between\nactive and inertial effects in setting flow and orientational organization of\nactive particles.",
        "positive": "Dynamical self-assembly of dipolar active Brownian particles in two\n  dimensions: Based on Brownian Dynamics (BD) simulations, we study the dynamical\nself-assembly of active Brownian particles with dipole-dipole interactions,\nstemming from a permanent point dipole at the particle center. The propulsion\ndirection of each particle is chosen to be parallel to its dipole moment. We\nexplore a wide range of motilities and dipolar coupling strengths and\ncharacterize the corresponding behavior based on several order parameters. At\nlow densities and low motilities, the most important structural phenomenon is\nthe aggregation of the dipolar particles into chains. Upon increasing the\nparticle motility, these chain-like structures break, and the system transforms\ninto a weakly correlated isotropic fluid. At high densities, we observe that\nthe motility-induced phase separation is strongly suppressed by the dipolar\ncoupling. Once the dipolar coupling dominates the thermal energy, the phase\nseparation disappears, and the system rather displays a flocking state, where\nparticles form giant clusters and move collective along one direction. We\nprovide arguments for the emergence of the flocking behavior, which is absent\nin the passive dipolar system."
    },
    {
        "anchor": "Critical scalings and jamming in thermal colloidal systems: During the jamming of thermal colloids, the first peak of the pair\ndistribution function shows a maximum height $g_1^{\\rm max}$. We find that\n$g_1^{\\rm max}$ is accompanied by significant change of material properties and\nthus signifies the transition from unjammed to jammed glasses. The scaling laws\nat $g_1^{\\rm max}$ lead to scaling collapse of structural and thermodynamic\nquantities, indicating the criticality of the T=0 jamming transition. The\nphysical significance of $g_1^{\\rm max}$ is highlighted by its coincidence with\nthe equality of the kinetic and potential energy and the maximum fluctuation of\nthe coordination number. In jammed glasses, we find the strong coupling between\nthe isostaticity and flattening of the density of vibrational states at the\nisostatic temperature scaled well with the compression.",
        "positive": "Discontinuous metric programming in liquid crystalline elastomers: Liquid crystalline elastomers (LCEs) are shape-changing materials that\nexhibit large deformations in response to applied stimuli. Local control of the\norientation of LCEs spatially directs the deformation of these materials to\nrealize spontaneous shape change in response to stimuli. Prior approaches to\nshape programming in LCEs utilize patterning techniques that involve the\ndetailed inscription of spatially varying nematic fields to produce sheets.\nThese patterned sheets deform into elaborate geometries with complex Gaussian\ncurvatures. Here, we present an alternative approach to realize shape-morphing\nin LCEs where spatial patterning of the crosslink density locally regulates the\nmaterial deformation magnitude on either side of a prescribed interface curve.\nWe also present a simple mathematical model describing the behavior of these\nmaterials. Further experiments coupled with the mathematical model demonstrate\nthe control of the sign of Gaussian curvature, which is used in combination\nwith heat transfer effects to design LCEs that self-clean as a result of\ntemperature-dependent actuation properties."
    },
    {
        "anchor": "Formulation and numerical implementation of micro-scale boundary\n  conditions for particle aggregates: The aim of this paper is to propose a novel methodology to deal with\nmicro-structural boundary conditions for the analysis of granular materials.\nThe response of the granular assembly is modelled through the discrete element\nmethod (DEM), consistent with a micro-macro homogenization scheme formulated in\nthe transition from a continuous to a discrete setting. The three classical\ntypes of boundary conditions (displacement, periodic and displacement) are\nimplemented with a servo-control method. Two types of algorithms are developed,\nwhich consider or not an initial prediction for the displacement field of the\nparticles. Additionally, to simulate in a more realistic manner the effect of\nmacroscopic deformation on the micro-structure, a mixed type of boundary\nconditions is introduced, i.e. a combination of classical boundary conditions.\nThe effectiveness of the algorithms is tested on a series of DEM simulations.\nThe influence of the micro-structural morphology and of the size of the\nmicro-structure on the overall response is finally investigated.",
        "positive": "Alignment interactions drive structural transitions in biological\n  tissues: Experimental evidence shows that there is a feedback between cell shape and\ncell motion. How this feedback impacts the collective behavior of dense cell\nmonolayers remains an open question. We investigate the effect of a feedback\nthat tends to align the cell crawling direction with cell elongation in a\nbiological tissue model. We find that the alignment interaction promotes\nnematic patterns in the fluid phase that eventually undergo a non-equilibrium\nphase transition into a quasi-hexagonal solid. Meanwhile, highly asymmetric\ncells do not undergo the liquid-to-solid transition for any value of the\nalignment coupling. In this regime, the dynamics of cell centers and shape\nfluctuation show features typical of glassy systems."
    },
    {
        "anchor": "Thermoresponsive Colloidal Molecules: We fabricated thermoresponsive colloidal molecules of ca. 250 nm size.\nElectron- and scanning force microscopy reveal the dumbbell-shaped morphology.\nThe temperature dependence of the size and aspect ratio (ca. 1.4 to 1.6) is\nanalyzed by depolarized dynamic light scattering and found to be in good\nagreement with microscopic evidence.",
        "positive": "The structure of deterministic mass and surface fractals: theory and\n  methods of analyzing small-angle scattering data: Small-angle scattering (SAS) of X-rays, neutrons or light from ensembles of\nrandomly oriented and placed deterministic fractal structures are studied\ntheoretically. In the standard analysis, a very few parameters can be\ndetermined from SAS data: the fractal dimension, and the lower and upper limits\nof the fractal range. The self-similarity of deterministic structures allows\none to obtain additional characteristics of their spatial structures. The paper\nconsiders models which can describe accurately SAS from such structures. The\ndeveloped models of deterministic fractals offer many advantages in describing\nfractal systems, including the possibility to extract additional structural\ninformation, an analytic description of SAS intensity, and effective\ncomputational algorithms. Generalized Cantor fractals and few of its variants\nare used as basic examples to illustrate the above concepts and to model\nphysical samples with mass, surface, and multi-fractal structures. The\ndifferences between the deterministic and random fractal structures in\nanalyzing SAS data are emphasized. Several limitations are identified in order\nto motivate future investigations of deterministic fractal structures."
    },
    {
        "anchor": "Interpretation of Light Scattering Spectra in Terms of Particle\n  Displacements: Quasi-elastic light scattering spectroscopy of dilute solutions of diffusing\nmesoscopic probe particles is regularly used to examine the dynamics of the\nfluid through which the probe particles are moving. For probes in a simple\nliquid, the light scattering spectrum is a simple exponential; the field\ncorrelation function $g^{(1)}_{P}(q,\\tau)$ of the scattering particles is\nrelated to their mean-square displacements $\\bar{X^{2}} \\equiv < (\\Delta\nx(\\tau))^{2}>$ during $\\tau$ via $g^{(1)}(q,\\tau) = \\exp(- {1/2} q^{2}\n\\bar{X^{2}})$. However, historical demonstrations of this expression refer only\nto ideal Brownian particles in simple liquids, and show that if the form is\ncorrect then it is also true that $g^{(1)}(q,\\tau) = \\exp(- \\Gamma \\tau)$, a\npure exponential in $\\tau$. In general, $g^{(1)}_{P}(q,\\tau)$ is not a single\nexponential in time. $g^{(1)}_{P}(q,\\tau)$ reflects not only the mean-square\nparticle displacements but also all higher-order mean displacement moments\n$\\bar{X^{2n}}$. A correct general form for $g^{(1)}(q,\\tau)$, replacing the\ngenerally-incorrect $\\exp(- {1/2} q^{2} \\bar{X^{2}})$, is obtained. A simple\nexperimental diagnostic determining when the field correlation function gives\nthe mean-square displacements is identified, namely $g^{(1)}(q,\\tau)$ reveals\n$\\bar{X^{2}}$ if $g^{(1)}(q,\\tau)$ is exponential in $\\tau$.",
        "positive": "Topological interactions in DNA catenanes: The elasticity of DNA catenanes, i.e. multiply linked DNA rings, is\ninvestigated using the Gauss invariant as a minimal model for topology\nconservation. An effective elastic free energy as a function of the distance\n$R$ between segments located on different rings is obtained. An anharmonic part\nat large distances, growing as $R^{4}$, if $R\\gg R_{G}$ ($R_{G}$ being the\nradius of gyration of a random walk ring) is found, while for $R\\ll R_{G}$ the\ninteraction is strongly repulsive. Treating the attractive interaction as the\ndominant one, distribution functions for the distance between segments located\non different rings for several linking numbers are derived which are in\nqualitative agreement with distributions functions obtained experimentally from\nelectron micrographs of DNA catenanes (S. D. Levene et al., Biophys.J. 69, 277,\n1995)."
    },
    {
        "anchor": "Tuning the pull-in instability of soft dielectric elastomers through\n  loading protocols: Pull-in (or electro-mechanical) instability occurs when a drastic decrease in\nthe thickness of a dielectric elastomer results in electrical breakdown, which\nlimits the applications of dielectric devices. Here we derive the criteria for\ndetermining the pull-in instability of dielectrics actuated by different\nloading methods: voltage-control, charge-control, fixed pre-stress and fixed\npre-stretch, by analyzing the free energy of the actuated systems. The Hessian\ncriterion identifies a maximum in the loading curve beyond which the elastomer\nwill stretch rapidly and lose stability, and can be seen as a path to failure.\nWe present numerical calculations for neo-Hookean ideal dielectrics, and obtain\nthe maximum allowable actuation stretch of a dielectric before failure by\nelectrical breakdown. We find that applying a fixed pre-stress or a fixed\npre-stretch to a charge-driven dielectric may decrease the stretchability of\nthe elastomer, a scenario which is the opposite of what happens in the case of\na voltage-driven dielectric. Results show that a reversible large actuation of\na dielectric elastomer, free of the pull-in instability, can be achieved by\ntuning the actuation method.",
        "positive": "Thermodynamic consistency between the energy and virial routes in the\n  mean spherical approximation for soft potentials: It is proven that, for any soft potential characterized by a finite Fourier\ntransform $\\widetilde{\\phi}(k)$, the virial and energy thermodynamic routes are\nequivalent for approximations such that the Fourier transform of the total\ncorrelation function divided by the density $\\rho$ is an arbitrary function of\n$\\rho\\beta\\widetilde{\\phi}(k)$, where $\\beta$ is the inverse temperature. This\nclass includes the mean spherical approximation as a particular case."
    },
    {
        "anchor": "Reentrant Phase Behavior in Active Colloids with Attraction: Motivated by recent experiments, we study a system of self-propelled colloids\nthat experience short-range attractive interactions and are confined to a\nsurface. Using simulations we find that the phase behavior for such a system is\nreentrant as a function of activity: phase-separated states exist in both the\nlow- and high-activity regimes, with a homogeneous active fluid in between. To\nunderstand the physical origins of reentrance, we develop a kinetic model for\nthe system's steady-state dynamics whose solution captures the main features of\nthe phase behavior. We also describe the varied kinetics of phase separation,\nwhich range from the familiar nucleation and growth of clusters to the complex\ncoarsening of active particle gels.",
        "positive": "Tunable Slow Dynamics in a New Class of Soft Colloids: By means of extensive simulations, we investigate concentrated solutions of\nglobular single-chain nanoparticles (SCNPs), an emergent class of synthetic\nsoft nano-objects. By increasing the concentration, the SCNPs show a reentrant\nbehaviour in their structural and dynamical correlations, as well as a soft\ncaging regime and weak dynamic heterogeneity. The latter is confirmed by\nvalidation of the Stokes-Einstein relation up to concentrations far beyond the\noverlap density. Therefore SCNPs arise as a new class of soft colloids,\nexhibiting slow dynamics and actualizing in a real system structural and\ndynamical anomalies proposed by models of ultrasoft particles. Quantitative\ndifferences in the dynamical behaviour depend on the SCNP deformability, which\ncan be tuned through the degree of internal cross-linking."
    },
    {
        "anchor": "Laboratory glass transition in granular gases and non-linear molecular\n  fluids: In this paper we investigate the emergence of a laboratory glass transition\nin two different physical systems: a uniformly heated granular gas and a\nmolecular fluid with non-linear drag. Despite the profound differences between\nthe two systems, their behaviour in thermal cycles share strong similarities.\nWhen the driving intensity -- for the granular gas -- or the bath temperature\n-- for the molecular fluid -- is decreased to sufficiently low values, the\nkinetic temperature of both systems becomes ``frozen\" at a value that depends\non the cooling rate through a power law with the same exponent. Interestingly,\nthis frozen glassy state is universal in the following sense: for a suitable\nrescaling of the relevant variables, its velocity distribution function becomes\nindependent of the cooling rate. Upon reheating, i.e. when either the driving\nintensity or the bath temperature is increased from this frozen state,\nhysteresis cycles arise and the apparent heat capacity displays a maximum. We\ndevelop a boundary layer perturbative theory that accurately explains the\nbehaviour observed in the numerical simulations.",
        "positive": "Enhanced dynamic homogenization of hexagonally packed granular materials\n  with elastic interfaces: It is well known that the classical energetically consistent micropolar model\nhas limits in simulating the frequency band structure of packed granular\nmaterials (see Merkel et al., 2011). It is here shown that if a standard\ncontinualization of the difference equation of motion of the discrete model is\ncarried out, an equivalent micropolar continuum is obtained which is able to\naccurately simulate the optical branches of the discrete model. Nevertheless,\nthis homogenized continuum presents non-positive defined elastic potential\nenergy, a deficiency that limits the reliability of the model and implies\ninstability phenomena (destabilizing effects) in the acoustic branches. This\ndrawback is circumvented here through an high-frequency dynamic homogenization\nscheme which is based on an enhanced continualization of the discrete governing\nequations into pseudo-differential equations. Through a formal Taylor expansion\nof the pseudo-differential operators a higher order differential equation\ncorresponding to the governing equation of a non-local continuum\nthermodynamically consistent are obtained. The resulting approach allows\nobtaining an equivalent micropolar continuum characterized by inertial\nnon-locality. Moreover, higher order continua with non-local constitutive and\ninertial terms may be derived. The proposed continuum models are proved to be\nable to accurately describe both the static and dynamic behavior of the\ndiscrete granular model. Finally, the convergence to the response of the\ndiscrete system is shown when increasing the order of the higher order\ncontinuum."
    },
    {
        "anchor": "Swelling and Dissolution of onion phases: The effect of temperature: Contact experiments have been performed between an onion lamellar phase and\nbrine, in the SDS/octanol/brine system. Using video microscopy we have studied\nthe nonequilibrium behaviour of the swelling and dissolution process of onions.\nExperiments at T=20degC and 30degC showed that temperature has a strong effect\non their bahaviour. At low temperature onions are observed to diffuse away from\nthe onion phase and only swell slightly. However by increasing the temperature\nwe induce the formation of the sponge phase at the onion/brine interface.\nOnions that initailly swell then dissolve into sponge phase expel a stable core\nwhich moves to the micellar phase and remains stable there. Over a longer\nperiod of time (several days) we have also observed coalescence leading to the\nformation of large onions of up to 100microns in diameter. These huge onions\nhave a radial distribution of domains, or solvent cavities, within them.",
        "positive": "Tunable capillary-induced attraction between vertical cylinders: Deformation of a fluid interface caused by the presence of objects at the\ninterface can lead to large lateral forces between the objects. We explore\nthese fluid-mediated attractive force between partially submerged vertical\ncylinders. Forces are experimentally measured by slowly separating cylinder\npairs and cylinder triplets after capillary rise is initially established for\ncylinders in contact. For cylinder pairs, numerical computations and a\ntheoretical model are found to be in good agreement with measurements. The\nmodel provides insight into the relative importance of the contributions to the\ntotal force. For small separations, the pressure term dominates, while at large\nseparations, surface tension becomes more important. A cross-over between the\ntwo regimes occurs at a separation of around half of a capillary length. The\nexperimentally measured forces between cylinder triplets are also in good\nagreement with numerical computations, and we show that pair-wise contributions\naccount for nearly all of the attractive force between triplets. For cylinders\nwith equilibrium capillary rise height greater than the height of the cylinder,\nwe find that the attractive force depends on the height of the cylinders above\nthe submersion level, which provides a means to create precisely-controlled\ntunable cohesive forces between objects deforming a fluid interface."
    },
    {
        "anchor": "Numerical investigation of local defectiveness control of diblock\n  copolymer patterns: We numerically investigate local defectiveness control of self-assembled\ndiblock copolymer patterns through appropriate substrate design. We use a\nnonlocal Cahn-Hilliard (CH) equation for the phase separation dynamics of\ndiblock copolymers. We discretize the nonlocal CH equation by an\nunconditionally stable finite difference scheme on a tapered trench design and,\nin particular, we use Dirichlet, Neumann, and periodic boundary conditions. The\nvalue at the Dirichlet boundary comes from an energy-minimizing equilibrium\nlamellar profile. We solve the resulting discrete equations using a\nGauss-Seidel iterative method. We perform various numerical experiments such as\neffects of channel width, channel length, and angle on the phase separation\ndynamics. The simulation results are consistent with the previous experimental\nobservations.",
        "positive": "On the cause of Zeta potential of a charged vesicle. The extra- and\n  intravesicular membrane charges contribute differently to the extra- and\n  intravesicular potential: When the charge densities on the inner and outer surface of the vesicle\nmembrane are similar one may assume that the potential at a point closer to the\nouter/inner surface is more affected by the charges located at the outer/inner\nsurface of the vesicle membrane. However, because of the curvature of the\nvesicle and the screening effect of the electrolyte ions the situation is more\ncomplicated. When the charge densities at the inner and outer surface of the\nvesicle membrane are the same then at any finite distance Z from the center of\nthe vesicle the contribution of the charges, located at the outer membrane\nsurface, to the vesicle potential Vex is different from the contribution of the\ncharges, located at the inner membrane surface, to the vesicle potential Vin.\nAt low electrolyte ion concentrations (from C=0 to 0.00001 [Mol]) Vex/Vin>1 and\nincreases with increasing distance from the center of the vesicle until the\nexternal surface of the vesicle membrane. With further increasing distance\nVex/Vin remains constant at C=0 [Mol], while at C>0 [Mol] it starts decreasing.\nHowever, at high electrolyte ion concentrations (C>0.01 [Mol]) with increasing\ndistance from the center of the vesicle Vex/Vin reaches its maximum at the\ninternal surface of the vesicle membrane. With further increasing distance,\nclose to the outer surface of the vesicle Vex/Vin becomes less than 1 (i.e. the\ncharges at the inner surface of the membrane contribute to the potential more\nthan the charges at the outer surface). Further increasing the distance Vex/Vin\nreaches its minimum and then increases to 1 (i.e. the charges at the inner\nsurface of the membrane contribute to the potential like the charges at the\nouter surface of the membrane). With increasing electrolyte ion concentration\nthe minimum of Vex/Vin is getting deeper (approaching zero) and its location is\ngetting closer to the outer surface of the vesicle."
    },
    {
        "anchor": "Current and diffusion of Overdamped Active Brownian Particles in a\n  Ratchet Potential: The transport properties of a spherical active Brownian particle in a\nperiodic potential under heavy damping are considered. The self-propelled\nparticle is subjected to the asymmetric potential, detailed balance is lost and\nthe particles generate a non-zero drift speed.\n  The average current is calculated and the diffusivity of the particle is\nanalyzed from the effective diffusion coefficient. For chiral active particles,\nthe diffusivity decreases with increasing the angular velocity, confining the\nparticle near the initial position, and reducing the average current.",
        "positive": "Odd elasticity and topological waves in active surfaces: Odd elasticity encompasses active elastic systems whose stress-strain\nrelationship is not compatible with a potential energy. As the requirement of\nenergy conservation is lifted from linear elasticity, new anti-symmetric (odd)\ncomponents appear in the elastic tensor. In this work, we study the odd\nelasticity and non-Hermitian wave dynamics of active surfaces, specifically\nplates of moderate thickness. We find that a free-standing moderately thick,\nisotropic plate can exhibit two odd-elastic moduli, both of which are related\nto shear deformations of the plate. These odd moduli can endow the vibrational\nmodes of the plate with a nonzero topological invariant known as the first\nChern number. Within continuum elastic theory, we show that the Chern number is\nrelated to the presence of unidirectional shearing waves that are hosted at the\nplate's boundary. We show that the existence of these chiral edge waves hinges\non a distinctive two-step mechanism: the finite thickness of the sample gaps\nthe shear modes and the odd elasticity endows them with chirality."
    },
    {
        "anchor": "On the size-distribution of Poisson Voronoi cells: Poisson Voronoi diagrams are useful for modeling and describing various\nnatural patterns and for generating random lattices. Although this particular\nspace tessellation is intensively studied by mathematicians, in two- and three\ndimensional spaces there is no exact result known for the size-distribution of\nVoronoi cells. Motivated by the simple form of the distribution function in the\none-dimensional case, a simple and compact analytical formula is proposed for\napproximating the Voronoi cell's size distribution function in the practically\nimportant two- and three dimensional cases as well. Denoting the dimensionality\nof the space by d (d=1,2,3) the $f(y)=Const*y^{(3d-1)/2}exp(-(3d+1)y/2)$\ncompact form is suggested for the normalized cell-size distribution function.\nBy using large-scale computer simulations the validity of the proposed\ndistribution function is studied and critically discussed.",
        "positive": "Hydrodynamic suppression of phase separation in active suspensions: We simulate with hydrodynamics a suspension of active disks squirming through\na Newtonian fluid. We explore numerically the full range of squirmer area\nfractions from dilute to close packed and show that \"motility induced phase\nseparation\" (MIPS), which was recently proposed to arise generically in active\nmatter, and which has been seen in simulations of active Brownian disks, is\nstrongly suppressed by hydrodynamic interactions. We give an argument for why\nthis should be the case and support it with counterpart simulations of active\nBrownian disks in a parameter regime that provides a closer counterpart to\nhydrodynamic suspensions than in previous studies."
    },
    {
        "anchor": "Photonic-crystal slabs with a triangular lattice of triangular holes\n  investigated using a guided-mode expansion method: According to a recent proposal [S. Takayama et al., Appl. Phys. Lett. 87,\n061107 (2005)], the triangular lattice of triangular air holes may allow to\nachieve a complete photonic band gap in two-dimensional photonic crystal slabs.\nIn this work we present a systematic theoretical study of this photonic lattice\nin a high-index membrane, and a comparison with the conventional triangular\nlattice of circular holes, by means of the guided-mode expansion method whose\ndetailed formulation is described here. Photonic mode dispersion below and\nabove the light line, gap maps, and intrinsic diffraction losses of\nquasi-guided modes are calculated for the periodic lattice as well as for line-\nand point-defects defined therein. The main results are summarized as follows:\n(i) the triangular lattice of triangular holes does indeed have a complete\nphotonic band gap for the fundamental guided mode, but the useful region is\ngenerally limited by the presence of second-order waveguide modes; (ii) the\nlattice may support the usual photonic band gap for even modes (quasi-TE\npolarization) and several band gaps for odd modes (quasi-TM polarization),\nwhich could be tuned in order to achieve doubly-resonant frequency conversion\nbetween an even mode at the fundamental frequency and an odd mode at the\nsecond-harmonic frequency; (iii) diffraction losses of quasi-guided modes in\nthe triangular lattices with circular and triangular holes, and in line-defect\nwaveguides or point-defect cavities based on these geometries, are comparable.\nThe results point to the interest of the triangular lattice of triangular holes\nfor nonlinear optics, and show the usefulness of the guided-mode expansion\nmethod for calculating photonic band dispersion and diffraction losses,\nespecially for higher-lying photonic modes.",
        "positive": "Intersonic Detachment Surface Waves in Elastomer Frictional Sliding: Elastomeric materials when sliding on clean and rough surfaces generate\nwrinkles at the interface due to tangential stress gradients. These interfacial\nfolds travel along the bottom of elastomer as surface detachment waves to\nfacilitate the apparent sliding motion of elastomer. At very low sliding speed\ncompared to elastic surface waves, the process is dominated by surface adhesion\nand relaxation effects, and the phenomenon is historically referred to as\nSchallamach waves. We report in this letter the observation of fast-traveling\nintersonic detachment waves exceeding the Rayleigh and shear wave velocities of\nthe soft material in contact. The spatio-temporal analysis revealed the\naccelerating nature of the detachment wave, and the scaling of wave speed with\nthe elastic modului of the material suggests that this process is governed by\nelasticity and inertia. Multiple wave signatures on the plot were connected to\ndifferent stages of surface wrinkles, as they exhibited distinctive slopes\n(from which velocities were derived) in the generation, propagation and rebound\nphases. We also characterized the frequencies of wrinkle generation in addition\nto the speeds and found a consistent scaling law of these two wave\ncharacteristics as the stiffness of elastomer increased. Physical implications\nof this new finding may further promote our understanding of elastomer noise\ngeneration mechanisms, as at macroscopic sliding velocity, the frequency of\nelastomer instability readily enters human audible ranges and interacts with\nother vibratory frequencies to cooperatively create harsh and detrimental\nnoises in disc braking, wiper blade and shoe squeaking among many other\nelastomer applications."
    },
    {
        "anchor": "Molecular modelling and simulation of electrolyte solutions,\n  biomolecules, and wetting of component surfaces: Massively-parallel molecular dynamics simulation is applied to systems\ncontaining electrolytes, vapour-liquid interfaces, and biomolecules in contact\nwith water-oil interfaces. Novel molecular models of alkali halide salts are\npresented and employed for the simulation of electrolytes in aqueous solution.\nThe enzymatically catalysed hydroxylation of oleic acid is investigated by\nmolecular dynamics simulation taking the internal degrees of freedom of the\nmacromolecules into account. Thereby, Ewald summation methods are used to\ncompute the long range electrostatic interactions. In systems with a phase\nboundary, the dispersive interaction, which is modelled by the Lennard-Jones\npotential here, has a more significant long range contribution than in\nhomogeneous systems. This effect is accounted for by implementing the Janecek\ncutoff correction scheme. On this basis, the HPC infrastructure at the\nSteinbuch Centre for Computing was accessed and efficiently used, yielding new\ninsights on the molecular systems under consideration.",
        "positive": "Entropic Origin of the Growth of Relaxation Times in Simple Glassy\n  Liquids: Transitions between ``glassy'' local minima of a model free-energy functional\nfor a dense hard-sphere system are studied numerically using a\n``microcanonical'' Monte Carlo method that enables us to obtain the transition\nprobability as a function of the free energy and the Monte Carlo ``time''. The\ngrowth of the height of the effective free energy barrier with density is found\nto be consistent with a Vogel-Fulcher law. The dependence of the transition\nprobability on time indicates that this growth is primarily due to entropic\neffects arising from the difficulty of finding low-free-energy saddle points\nconnecting glassy minima."
    },
    {
        "anchor": "Auxetic Granular Metamaterials: The flowing, jamming and avalanche behavior of granular materials is\nsatisfyingly universal and vexingly hard to tune: a granular flow is typically\nintermittent and will irremediably jam if too confined. Here, we show that\ngranular metamaterials made from particles with a negative Poisson's ratio\nyield more easily and flow more smoothly than ordinary granular materials. We\nfirst create a collection of auxetic grains based on a re-entrant mechanism and\nshow that each grain exhibits a negative Poisson's ratio regardless of the\ndirection of compression. Interestingly, we find that the elastic and yielding\nproperties are governed by the high compressibility of granular metamaterials:\nat a given confinement they exhibit lower shear modulus, lower yield stress and\nmore frequent, smaller avalanches than materials made from ordinary grains. We\nfurther demonstrate that granular metamaterials promote flow in more complex\nconfined geometries, such as intruder and hopper geometries, even when the\npacking contains only a fraction of auxetic grains. Our findings blur the\nboundary between complex fluids and metamaterials and could help in scenarios\nthat involve process, transport and reconfiguration of granular materials.",
        "positive": "Direct Observation of Entropic Stabilization of bcc Crystals Near\n  Melting: Crystals with low latent heat are predicted to melt from an entropically\nstabilized body-centered cubic symmetry. At this weakly first-order transition,\nstrongly correlated fluctuations are expected to emerge, which could change the\nnature of the transition. Here we show how large fluctuations stabilize bcc\ncrystals formed from charged colloids, giving rise to strongly power-law\ncorrelated heterogeneous dynamics. Moreover, we find that significant nonaffine\nparticle displacements lead to a vanishing of the nonaffine shear modulus at\nthe transition. We interpret these observations by reformulating the Born-Huang\ntheory to account for nonaffinity, illustrating a scenario of ordered solids\nreaching a state where classical lattice dynamics fail."
    },
    {
        "anchor": "Theoretical study of the magnetization dynamics of non-dilute\n  ferrofluids: The paper is devoted to the theoretical investigation of the magnetodipolar\ninterparticle interaction effect on remagnetization dynamics in moderately\nconcentrated ferrofluids. We consider a homogeneous (without particle\naggregates) ferrofluid consisting of identical spherical particles and employ a\nrigid dipole model, where magnetic moment of a particle is fixed with respect\nto the particle itself. In particular, for the magnetization relaxation after\nthe external field is instantly switched off, we show that the magnetodipolar\ninteraction leads to the increase of the initial magnetization relaxation time.\nFor the complex ac-susceptibility we find that the this interaction leads to an\noverall increase of the imaginary susceptibility part and shifts the peak on\nits frequency dependence towards lower frequencies. Comparing results obtained\nwith our analytical approach (second order virial expansion) to numerical\nsimulation data (Langevin dynamics method), we demonstrate that the employed\nvirial expansion approximation gives a good qualitative description of the\nferrofluid magnetization dynamics and provides a satisfactory quantitative\nagreement with numerical simulations for the dc magnetization relaxation - up\nto the particle volume fraction c ~ 10% and for the ac-susceptibility - up to c\n~ 5 %.",
        "positive": "Investigating model influence on the analytical resolution of neutron\n  reflectometry: Neutron reflectometry is a critical tool for investigating the structure of\nthin films and interfaces. However, the misapplication of the Born\napproximation to reflection geometry leads some to assume that the minimum\nthickness that may be probed by neutron reflectometry is limited by the Q-range\nof the measurement. In this study, we use model-dependent analysis, multiple\nisotopic contrasts, and magnetic spin states, to show that it is possible to\nresolve structures significantly smaller than this perceived limit. To quantify\nthis \"analytical resolution\", we employ Bayesian model selection, offering a\nrobust and quantifiable comparison between different analytical models. We\nbelieve that this work offers pivotal insights for the analysis of neutron\nreflectometry and hope that it will contribute to more accurate and\ninformation-rich analyses in the future."
    },
    {
        "anchor": "Sandpile Models of Self-Organized Criticality: Self-Organized Criticality is the emergence of long-ranged spatio-temporal\ncorrelations in non-equilibrium steady states of slowly driven systems without\nfine tuning of any control parameter. Sandpiles were proposed as prototypical\nexamples of self-organized criticality. However, only some of the laboratory\nexperiments looking for the evidence of criticality in sandpiles have reported\na positive outcome. On the other hand a large number of theoretical models have\nbeen constructed that do show the existence of such a critical state. We\ndiscuss here some of the theoretical models as well as some experiments.",
        "positive": "Reaching to a small target: entropic barriers and rates of specific\n  binding of polymer to substrate: This paper considers a broadly biologically relevant question of a chain\n(such as a protein) binding to a sequence of receptors with matching multiple\nligands distributed along the chain. This binding is critical in cell adhesion\nevents, and in protein self-assembly. Using a mean field approximation of\npolymer dynamics, we first calculate the characteristic binding time for a\ntethered ligand reaching for a specific binding site on the surface. This time\nis determined by two separate entropic effects: an entropic barrier for the\nchain to be stretched sufficiently to reach the distant target, and a\nrestriction on chain conformations near the surface. We then derive the\ncharacteristic time for a sequence of single binding events, and find that it\nis determined by the `zipper effect', optimizing the sequence of single and\nmultiple binding steps."
    },
    {
        "anchor": "Dilute concentrations of submicron particles do not alter the brittle\n  fracture of polyacrylamide hydrogels: In studies of the dynamic failure of brittle hydrogels, a bound has been\nplaced on the process zone scale - the scale where material separation and\nultimate failure occur. For the polyacrylamide hydrogel system under study,\nthis bound is set at 20 microns. Thus, any subtle alterations to the material\nat a \\emph{smaller} scale should not in principle alter the dynamic fracture\nresponse of the hydrogel. Here we test this directly by embedding\nsub-micron-scale latex polystyrene microspheres within the brittle\npolyacrylamide hydrogel at a solids fraction of 0.1 \\%. We verify that the\nspheres are well-distributed throughout the hydrogel material at this\nconcentration with optical microscopy, and reconstruct the 3D distribution of\nthese spheres using laser scanning confocal microscopy in backscatter mode.\nFinally, we test the fracture behavior of this gel with the dilute, embedded\nsub-micron spheres, and find that the brittle material failure modality common\nto this material \\emph{without} the sub-micron spheres is indeed retained. By\ncomparing the crack tip opening displacement, fracture energy and the crack's\nspeed with established data from prior experimental work, we demonstrate that\nthis material's failure is brittle, as it is in good agreement with the pure\nhydrogel system.",
        "positive": "Strictly two-dimensional self-avoiding walks: Thermodynamic properties\n  revisited: The density crossover scaling of various thermodynamic properties of\nsolutions and melts of self-avoiding and highly flexible polymer chains without\nchain intersections confined to strictly two dimensions is investigated by\nmeans of molecular dynamics and Monte Carlo simulations of a standard\ncoarse-grained bead-spring model. In the semidilute regime we confirm over an\norder of magnitude of the monomer density rho the expected power-law scaling\nfor the interaction energy between different chains e_inter\\sim\\rho^(21/8), the\ntotal pressure P\\sim\\rho^3 and the dimensionless compressibility\ngT=lim(q->0)(S(q)\\sim1/\\rho^2). Various elastic contributions associated to the\naffine and non-affine response to an infinitesimal strain are analyzed as\nfunctions of density and sampling time. We show how the size xi(rho) of the\nsemidilute blob may be determined experimentally from the total monomer\nstructure factor S(q) characterizing the compressibility of the solution at a\ngiven wavevector q. We comment briefly on finite persistence length effects."
    },
    {
        "anchor": "Phase behavior of grafted chain molecules: Influence of head size and\n  chain length: Constant pressure Monte Carlo simulations of a coarse grained off-lattice\nmodel for monolayers of amphiphilic molecules at the air/water interface are\npresented. Our study focusses on phase transitions within a monolayer rather\nthan on self aggregation. We thus model the molecules as stiff chains of\nLennard-Jones spheres with one slightly larger repulsive end bead (head)\ngrafted to a planar surface. Depending on the size of the head, the temperature\nand the pressure, we find a variety of phases, which differ in tilt order\n(including tilt direction), and in positional order. In particular, we observe\na modulated phase with a striped superstructure. The modulation results from\nthe competition between two length scales, the head size and the tail diameter.\nAs this mechanism is fairly general, it may conceivably also be relevant in\nexperimental monolayers. We argue that the superstructure would be very\ndifficult to detect in a scattering experiment, which perhaps accounts for the\nfact that it has not been reported so far. Finally the effect of varying the\nchain length on the phase diagram is discussed. Except at high pressures and\ntemperatures, the phase boundaries in systems with longer chains are shifted to\nhigher temperatures.",
        "positive": "On the shear-thinning of alkanes: The approximate power-law dependence of the apparent viscosity of liquids on\nshear rate is often argued to arise from a distribution of energy barriers.\nHowever, recent work on the Prandtl model, which consists of a point mass being\ndragged by a damped, harmonic spring past a sinusoidal potential, revealed a\nsimilar dependence of the friction on velocity as that of many liquids. Here,\nwe demonstrate that this correlation is not only qualitative but can also be\nmade quantitative over a broad temperature range using merely three\ndimensionless parameters, at least for alkanes, in particular hexadecane, at\nelevated pressure p. These and other observations made on our all-atom alkane\nsimulations at elevated pressure point to the existence of an elementary\ninstability causing shear thinning. In addition, the equilibrium viscosity\nshows power law dependence on p near the cavitation pressure but an exponential\ndependence at large p, while the additional parameter(s) in the Carreau-Yasuda\nequation compared to other rheological models turn out justifiable."
    },
    {
        "anchor": "An analysis of the far-field response to external forcing of a\n  suspension in Stokes flow in a parallel-wall channel: The leading-order far-field scattered flow produced by a particle in a\nparallel-wall channel under creeping flow conditions has a form of the\nparabolic velocity field driven by a 2D dipolar pressure distribution. We show\nthat in a system of hydrodynamically interacting particles, the pressure\ndipoles contribute to the macroscopic suspension flow in a similar way as the\ninduced electric dipoles contribute to the electrostatic displacement field.\nUsing this result we derive macroscopic equations governing suspension\ntransport under the action of a lateral force, a lateral torque or a\nmacroscopic pressure gradient in the channel. The matrix of linear transport\ncoefficients in the constitutive relations linking the external forcing to the\nparticle and fluid fluxes satisfies the Onsager reciprocal relation. The\ntransport coefficients are evaluated for square and hexagonal periodic arrays\nof fixed and freely suspended particles, and a simple approximation in a\nClausius-Mossotti form is proposed for the channel permeability coefficient. We\nalso find explicit expressions for evaluating the periodic Green's functions\nfor Stokes flow between two parallel walls.",
        "positive": "Capillary filtering of particles during dip coating: An object withdrawn from a liquid bath is coated with a thin layer of liquid.\nAlong with the liquid, impurities such as particles present in the bath can be\ntransferred to the withdrawn substrate. Entrained particles locally modify the\nthickness of the film, hence altering the quality and properties of the\ncoating. In this study, we show that it is possible to entrain the liquid alone\nand avoid contamination of the substrate, at sufficiently low withdrawal\nvelocity in diluted suspensions. Using a model system consisting of a plate\nexiting a liquid bath, we observe that particles can remain trapped in the\nmeniscus which exerts a resistive capillary force to the entrainment. We\ncharacterize different entrainment regimes as the withdrawal velocity\nincreases: from a pure liquid film, to a liquid film containing clusters of\nparticles, and eventually individual particles. This capillary filtration is an\neffective barrier against the contamination of substrates withdrawn from a\npolluted bath and finds application against biocontamination."
    },
    {
        "anchor": "Visualization of latent and depleted fingermarks on CDs and DVDs using\n  columnar thin films: CDs and DVDs are forensically important substrates for latent fingermarks.\nUpright columnar thin films (CTFs) grown conformally over these substrates were\nshown to significantly enhance the visual quality of fingermarks. Enhancement\nto maximum possible grade for visual quality occurred, even for the samples\nthat were developed three days after the fingermarks were placed on them. The\nCTFs were deposited by directing a collimated vapor flux of an evaporant\nmaterial towards the substrate placed at an angle and made to rotate rapidly.",
        "positive": "Distribution of volumes and coordination number in jammed matter:\n  mesoscopic ensemble: We investigate the distribution of the volume and coordination number\nassociated to each particle in a jammed packing of monodisperse hard sphere\nusing the mesoscopic ensemble developed in Nature 453, 606 (2008). Theory\npredicts an exponential distribution of the orientational volumes for random\nclose packings and random loose packings. A comparison with computer generated\npackings reveals deviations from the theoretical prediction in the volume\ndistribution, which can be better modeled by a compressed exponential function.\nOn the other hand, the average of the volumes is well reproduced by the theory\nleading to good predictions of the limiting densities of RCP and RLP. We\ndiscuss a more exact theory to capture the volume distribution in its entire\nrange. The available data suggests a plausible order/disorder transition\ndefining random close packings. Finally, we consider an extended ensemble to\ncalculate the coordination number distribution which is shown to be of an\nexponential and inverse exponential form for coordinations larger and smaller\nthan the average, respectively, in reasonable agreement with the simulated\ndata."
    },
    {
        "anchor": "Generalized loading-unloading contact laws for elasto-plastic spheres\n  with bonding strength: We present generalized loading-unloading contact laws for elasto-plastic\nspheres with bonding strength. The proposed mechanistic contact laws are\ncontinuous at the onset of unloading by means of a regularization term, in the\nspirit of a cohesive zone model, that introduces a small and controllable error\nin the conditions for interparticle breakage. This continuity property is in\nsharp contrast with the behavior of standard mechanistic loading and unloading\ncontact theories, which exhibit a discontinuity at the onset of unloading when\nparticles form solid bridges during plastic deformation. The formulation\ndepends on five material properties, namely two elastic properties (Young's\nmodulus and Poisson's ratio), two plastic properties (a plastic stiffness and a\npower-law hardening exponent) and one fracture mechanics property (fracture\ntoughness), and its predictions are in agreement with detailed finite-element\nsimulations. The numerical robustness and efficiency of the proposed\nformulation are borne out by performing three-dimensional particle mechanics\nstatic calculations of microstructure evolution during the three most important\nsteps of powder die-compaction, namely during compaction, unloading, and\nejection. These simulations reveal the evolution, up to relative densities\nclose to one, of microstructural features, process variables and compact\nmechanical attributes which are quantitatively similar to those experimentally\nobserved and in remarkable agreement with the (semi-)empirical formulae\nreported in the literature.",
        "positive": "Hydrodynamic instabilities, waves and turbulence in spreading epithelia: We present a hydrodynamic model of spreading epithelial monolayers as polar\nviscous fluids, with active contractility and traction on the substrate. The\ncombination of both active forces generate an instability that leads to\nnonlinear traveling waves, which propagate in the direction of polarity with\ncharacteristic time scales that depend on contact forces. We show that a\nviscous fluid model explains a variety of observations on the slow dynamics of\nepithelial monolayers, in particular those that had been interpreted before as\nsignatures of elasticity. The non-elastic nature of the waves can be tested on\nthe basis of simple predictions of the model. Our theoretical framework\nprovides new insights such as the interpretation of plithotaxis as a result of\na strong flow-polarity coupling, and the quantification of collective\nforce-transmission of cells in terms of the non-locality of interactions. In\naddition, we study the nonlinear regime of those waves deriving an exact map of\nthe model into the Complex Ginzburg-Landau equation, which provides a complete\nclassification of possible nonlinear scenarios. In particular, we predict the\ntransition to different forms of weak turbulence, which in turn could explain\nthe very unstable and irregular dynamics often observed in epithelia."
    },
    {
        "anchor": "Shape variation of micelles in polymer thin films: The equilibrium properties of block copolymer micelles confined in polymer\nthin films are investigated using self-consistent field theory. The theory is\nbased on a model system consisting of AB diblock copolymers and A homopolymers.\nTwo different methods, based on the radius of gyration tensor and the spherical\nharmonics expansion, are used to characterize the micellar shape. The results\nreveal that the morphology of micelles in thin films depends on the thickness\nof the thin films and the selectivity of the confining surfaces. For spherical\n(cylindrical) micelles, the spherical (cylindrical) symmetry is broken by the\npresence of the one-dimensional confinement, whereas the top-down symmetry is\nbroken by the selectivity of the confining surfaces. Morphological transitions\nfrom spherical or cylindrical micelles to cylinders or lamella are predicted\nwhen the film thickness approaches the micellar size.",
        "positive": "Stability of particle laden interfaces of drops flowing through a pore: When a drop laden with solid particles and suspended in a liquid passes\nthrough a narrow pore, its interface experiences strong shear and elongation,\nand the raft of particles may accumulate toward the back of the drop. Using\nwell controlled formulations of Pickering drops driven at set pressure, we\ndetermine the two conditions for which solid particles are expelled from the\noil-water interface after a Pickering drop passes a converging-diverging pore:\n(i) particles accumulation at the rear of the drop is such that surface\npressure builds-up at the interface. (ii) Surface pressure relaxation by\nbuckling is impaired by geometrical constraints. These two conditions are\nrationalized using three non dimensional numbers: the capillary number, the\nparticle to pore size ratio, and the drop to particle size ratio, which allow\nto account for the viscous shear at the interface, the stability of the\nlubricating film between the pore wall and the drop, the drag on the raft of\nparticles adsorbed at the interface, and its mechanical behaviour."
    },
    {
        "anchor": "Effect of particle geometry on phase transitions in two-dimensional\n  liquid crystals: Using a version of density-functional theory which combines Onsager\napproximation and fundamental-measure theory for spatially nonuniform phases,\nwe have studied the phase diagram of freely rotating hard rectangles and hard\ndiscorectangles. We find profound differences in the phase behavior of these\nmodels, which can be attributed to their different packing properties.\nInterestingly, bimodal orientational distribution functions are found in the\nnematic phase of hard rectangles, which cause a certain degree of biaxial\norder, albeit metastable with respect to spatially ordered phases. This feature\nis absent in discorectangles, which always show unimodal behavior. This result\nmay be relevant in the light of recent experimental results which have\nconfirmed the existence of biaxial phases. We expect that some perturbation of\nthe particle shapes (either a certain degree of polydispersity or even bimodal\ndispersity in the aspect ratios) may actually destabilize spatially ordered\nphases thereby stabilizing the biaxial phase.",
        "positive": "Reconfigurable assembly of nematic colloids commanded by photoactivated\n  surface patterns: Different phoretic driving mechanisms have been proposed for the transport of\nsolid or liquid microscopic inclusions in integrated chemical processes.\nHowever, the ability to reversibly address both the flow path, rate, and local\nreactant concentration has not yet been realized. Here we show that a substrate\nchemically modified with photosensitive self-assembled monolayers allows to\ndirectly command the assembly and transport of large ensembles of micron-size\nparticles and drops dispersed in a thin layer of anisotropic fluid. Our\nstrategy separates particle driving, realized via AC electrophoresis, and\nsteering, achieved by elastic modulation of the host nematic fluid. Inclusions\nrespond individually or in collective modes following arbitrary reconfigurable\npaths imprinted via UV/blue illumination. Relying solely on generic material\nproperties, the proposed procedure is versatile enough for the development of\napplications involving either inanimate or living materials."
    },
    {
        "anchor": "Interacting fluids in an arbitrary external field: We present new method for studying the equilibrium properties of interacting\nfluids in an arbitrary external filed. The method is valid in any dimension and\nit yields an exact results in one dimension. Using this approach, we derive a\nrecurrence relation for the pair distribution function of a three dimensional\nin-homogeneous fluids, constitute of spherical molecules with arbitrary nearest\nneighbour interaction that extends to two molecules diameter. By integrating\nthis recurrence relation, we get an explicit expressions for the entropy and\nfree energy functionals as a functionals of the density and the pair\ndistribution function. We show that for one dimensional systems, our results\ncoincide exactly with previously derived one using a completely different\napproach.",
        "positive": "Spatiotemporal dynamics of frictional systems: The interplay of\n  interfacial friction and bulk elasticity: Frictional interfaces are abundant in natural and engineering systems, and\npredicting their behavior still poses challenges of prime scientific and\ntechnological importance. At the heart of these challenges lies the inherent\ncoupling between the interfacial constitutive relation -- the macroscopic\nfriction law -- and the bulk elasticity of the bodies that form the frictional\ninterface. In this feature paper, we discuss the generic properties of the\nmacroscopic friction law and the many ways in which its coupling to bulk\nelasticity gives rise to rich spatiotemporal frictional dynamics. We first\npresent the widely used rate-and-state friction constitutive framework, discuss\nits power and limitations, and propose extensions that are supported by\nexperimental data. We then discuss how bulk elasticity couples different parts\nof the interface, and how the range and nature of this interaction are affected\nby the system's geometry. Finally, in light of the coupling between interfacial\nand bulk physics, we discuss basic phenomena in spatially-extended frictional\nsystems, including the stability of homogeneous sliding, the onset of sliding\nmotion and a wide variety of propagating frictional modes (e.g. rupture fronts,\nhealing fronts and slip pulses). Overall, the results presented and discussed\nin this feature paper highlight the inseparable roles played by interfacial and\nbulk physics in spatially-extended frictional systems."
    },
    {
        "anchor": "Critical scaling for dense granular flow between parallel plates near\n  jamming: We numerically study the flow of dense granular materials between parallel\nplates driven by an external force. The granular materials form a jammed\nsolid-like state when the external force is below a critical force, while they\nflow like fluids above the critical force. The transition is characterized by\nthe mass flux. The critical force depends on the average packing fraction and\nthe distance between the plates. The scaling laws for the critical force and\nthe mass flux are predicted theoretically based on a continuum model. They are\nnumerically verified.",
        "positive": "Johari-Goldstein heterogeneous dynamics in a model polymer: The heterogeneous character of the Johari-Goldstein (JG) relaxation is\nevidenced by molecular-dynamics simulation of a model polymer system. A\ndouble-peaked evolution of dynamic heterogeneity (DH), with maxima located at\nJG and structural relaxation time scales, is observed and mechanistically\nexplained. {The short-time single-particle displacement during JG relaxation\nweakly correlates with the long-time one observed during structural\nrelaxation}."
    },
    {
        "anchor": "Forced-induced desorption of a polymer chain adsorbed on an attractive\n  surface - Theory and Computer Experiment: We consider the properties of a self-avoiding polymer chain, adsorbed on a\nsolid attractive substrate which is attached with one end to a pulling force.\nThe conformational properties of such chain and its phase behavior are treated\nwithin a Grand Canonical Ensemble (GCE) approach. We derive theoretical\nexpressions for the mean size of loops, trains, and tails of an adsorbed chain\nunder pulling as well as values for the universal exponents which describe\ntheir probability distribution functions. A central result of the theoretical\nanalysis is the derivation of an expression for the crossover exponent $\\phi$,\ncharacterizing polymer adsorption at criticality, $\\phi = \\alpha -1$, which\nrelates the precise value of $\\phi$ to the exponent $\\alpha$, describing\npolymer loop statistics. We demonstrate that $1-\\gamma_{11} < \\alpha < 1 +\n\\nu$, depending on the possibility of a single loop to interact with\nneighboring loops in the adsorbed polymer. The universal surface loop exponent\n$\\gamma_{11} \\approx -0.39$ and the Flory exponent $\\nu \\approx 0.59$.\n  We present the adsorption-desorption phase diagram of a polymer chain under\npulling and demonstrate that the relevant phase transformation becomes first\norder whereas in the absence of external force it is known to be a continuous\none. The nature of this transformation turns to be dichotomic, i.e.,\ncoexistence of different phase states is not possible. These novel theoretical\npredictions are verified by means of extensive Monte Carlo simulations.",
        "positive": "Calculating hydrodynamic interactions for membrane-embedded objects: A recently introduced numerical scheme for calculating self-diffusion\ncoefficients of solid objects embedded in lipid bilayer membranes is extended\nto enable calculation of hydrodynamic interactions between multiple objects.\nThe method is used to validate recent analytical predictions by Oppenheimer and\nDiamant [Biophys. J., 96, 3041, 2009] related to the coupled diffusion of\nmembrane embedded proteins and is shown to converge to known near-field\nlubrication results as objects closely approach one another, however the\npresent methodology also applies outside of the limiting regimes where\nanalytical results are available. Multiple different examples involving pairs\nof disk-like objects with various constraints imposed on their relative motions\ndemonstrate the importance of hydrodynamic interactions in the dynamics of\nproteins and lipid domains on membrane surfaces. It is demonstrated that the\nrelative change in self-diffusion of a membrane embedded object upon\nperturbation by a similar proximal solid object displays a maximum for object\nsizes comparable to the Saffman-Delbr\\\"uck length of the membrane."
    },
    {
        "anchor": "Novel non-equilibrium steady states in multiple emulsions: We numerically investigate the rheological response of a non-coalescing\nmultiple emulsion under a symmetric shear flow. We find that the dynamics\nsignificantly depends on the magnitude of the shear rate and on the number of\nthe encapsulated droplets, two key parameters whose control is fundamental to\naccurately select the resulting non-equilibrium steady states. The double\nemulsion, for instance, attains a static steady state in which the external\ndroplet stretches under flow and achieves an elliptical shape (closely\nresembling the one observed in a sheared isolated fluid droplet), while the\ninternal one remains essentially unaffected. Novel non-equilibrium steady\nstates arise in a multiple emulsion. Under a low/moderate shear rates, for\ninstance, the encapsulated droplets display a non-trivial planetary-like motion\nthat considerably affects the shape of the external droplet. Some features of\nthis dynamic behavior are partially captured by the Taylor deformation\nparameter and the stress tensor. Besides a theoretical interest on its own, our\nresults can potentially stimulate further experiments, as most of the\npredictions could be tested in the lab by monitoring droplets shapes and\nposition over time.",
        "positive": "Cooperation among tumor cell subpopulations leads to intratumor\n  heterogeneity: Heterogeneity is a hallmark of all cancers. Tumor heterogeneity is found at\ndifferent levels -- interpatient, intrapatient, and intratumor heterogeneity.\nAll of them pose challenges for clinical treatments. The latter two scenarios\ncan also increase the risk of developing drug resistance. Although the\nexistence of tumor heterogeneity has been known for two centuries, a clear\nunderstanding of its origin is still elusive, especially at the level of\nintratumor heterogeneity (ITH). The coexistence of different subpopulations\nwithin a single tumor has been shown to play crucial roles during all stages of\ncarcinogenesis. Here, using concepts from evolutionary game theory and public\ngoods game, often invoked in the context of the tragedy of commons, we explore\nhow the interactions among subclone populations influence the establishment of\nITH. By using an evolutionary model, which unifies several experimental results\nin distinct cancer types, we develop quantitative theoretical models for\nexplaining data from {\\it in vitro} experiments involving pancreatic cancer as\nwell as {\\it vivo} data in glioblastoma multiforme. Such physical and\nmathematical models complement experimental studies, and could optimistically\nalso provide new ideas for the design of efficacious therapies for cancer\npatients."
    },
    {
        "anchor": "Anomalous dynamics of intruders in a crowded environment of mobile\n  obstacles: Many natural and industrial processes rely on constrained transport, such as\nproteins moving through cells, particles confined in nanocomposite materials or\ngels, individuals in highly dense collec- tives and vehicular traffic\nconditions. These are examples of motion through crowded environments, in which\nthe host matrix may retain some glass-like dynamics. Here we investigate\nconstrained transport in a colloidal model system, in which dilute small\nspheres move in a slowly rearranging, glassy matrix of large spheres. Using\nconfocal differential dynamic microscopy and simulations, we discover a\ncritical size asymmetry at which anomalous collective transport of the small\nparticles appears, manifested as a logarithmic decay of the density\nautocorrelation functions. We demonstrate that the matrix mobility is central\nfor the observed anomalous behaviour. These results, crucially depending on\nsize-induced dynamic asymmetry, are of relevance for a wide range of phenomena\nranging from glassy systems to cell biology.",
        "positive": "Proportional correlation between heat capacity and thermal expansion of\n  atomic, molecular crystals and carbon nanostructures: Correlation between thermal expansions $\\beta(T)$ and heat capacity $C(T)$ of\natomic and molecular crystals, amorphous materials with a structural disorder,\ncarbon nanomaterials (fullerite C$_{60}$, bundles SWCNTs of single-walled\ncarbon nanotubes) was analyzed. The influence of the contribution to the\ncoefficient of linear thermal expansion $\\alpha_\\textrm{Xe}(T)$ of Xe atoms\nadsorbed on the SWCNTs bundles is considered. The proportional correlation was\nfound between the contribution to the coefficient of linear thermal expansion\n$\\alpha_\\textrm{Xe}(T)$ and the normalized to the gas constant heat capacity\n$C_\\textrm{Xe}(T)/R$ of Xe atoms adsorbed on the SWCNTs bundles. The\nproportional correlation $(\\beta/\\beta^*) \\sim (C_\\textrm{V}/R)$ with the\nparameter $\\beta^*$ for the bulk thermal expansion coefficient for cryocrystals\nis proposed. In the case of atomic crystals such as Xe and Ar, the proportional\ncorrelation $(\\beta/\\beta^*) \\sim (C_\\textrm{V}/R)$ is observed in the\ntemperature range from the lowest experimental to temperatures where\n$C_\\textrm{V}/R \\approx 2.3$. The correlation is not observed in the\ntemperatures where $2.3<C_V/R<3$ (classical Dulong-Petit law). It was found\nthat the universal proportional correlation is also observed for molecular\ncrystals with linear symmetry, such as CO$_{2}$, CO, and N$_{2}$O if the\nnormalized heat capacity below the values $C_\\textrm{V}/R \\approx 3 \\div 3.5$."
    },
    {
        "anchor": "Mean field theory of yielding under oscillatory shear: We study a mean field elastoplastic model, embedded within a disordered\nlandscape of local yield barriers, to shed light on the behaviour of athermal\namorphous solids subject to oscillatory shear. We show that the model presents\na genuine dynamical transition between an elastic and a yielded state, and\nqualitatively reproduces the dependence on the initial degree of annealing\nfound in particle simulations. For initial conditions prepared below the\nanalytically derived threshold energy, we observe a non-trivial, non-monotonic\napproach to the yielded state. The timescale diverges as one approaches the\nyielding point from above, which we identify with the fatigue limit. We finally\ndiscuss the connections to brittle yielding under uniform shear.",
        "positive": "ESPResSo++ 2.0: Advanced methods for multiscale molecular simulation: Molecular simulation is a scientific tool dealing with challenges in material\nscience and biology. This is reflected in a permanent development and\nenhancement of algorithms within scientific simulation packages. Here, we\npresent computational tools for multiscale modeling developed and implemented\nwithin the ESPResSo++ package. These include the latest applications of the\nadaptive resolution scheme, the hydrodynamic interactions through a lattice\nBoltzmann solvent coupled to particle-based molecular dynamics, the\nimplementation of the hierarchical strategy for equilibrating long-chained\npolymer melts and a heterogeneous spatial domain decomposition.\n  The software design of ESPResSo++ has kept its highly modular C++ kernel with\na Python user interface. Moreover, it was enhanced by automatic scripts parsing\nconfigurations from other established packages providing scientists with a\nrapid setup possibility for their simulations."
    },
    {
        "anchor": "Noisy kink in microtubules: We study the power spectrum of a class of noise effects generated by means of\na digital-like disorder in the traveling variable of the conjectured\nGinzburg-Landau-Montroll kink excitations moving along the walls of the\nmicrotubules. We have found a 1/f^{\\alpha} noise with \\alpha \\in (1.82-2.04) on\nall the time scales we have considered",
        "positive": "Ordered droplet structures at the liquid crystal surface and\n  elastic-capillary colloidal interactions: We demonstrate a variety of ordered patterns, including hexagonal structures\nand chains, formed by colloidal particles (droplets) at the free surface of a\nnematic liquid crystal (LC). The surface placement introduces a new type of\nparticle interaction as compared to particles entirely in the LC bulk. Namely,\ndirector deformations caused by the particle lead to distortions of the\ninterface and thus to capillary attraction. The elastic-capillary coupling is\nstrong enough to remain relevant even at the micron scale when its\nbuoyancy-capillary counterpart becomes irrelevant."
    },
    {
        "anchor": "Structural signatures of strings and propensity for mobility in a\n  simulated supercooled liquid above the glass transition: By molecular dynamics (MD) simulation of the one-component Dzugutov liquid in\na metastable equilibrium supercooled state approaching the glass transition, we\ninvestigate the structural properties of highly mobile particles moving in\nstrings at low temperature T where string-like particle motion (SLM) is well\ndeveloped. We find that SLM occurs most frequently in the boundary regions\nbetween clusters of icosahedrally-ordered particles and disordered,\nliquid-like, domains. Further, we find that the onset T for significant SLM\ncoincides with the T at which clusters of icosahedrally-ordered particles begin\nto appear in considerable amounts, which in turn coincides with the onset T for\nnon-Arrhenius dynamics. We find a unique structural environment for strings\nthat is different from the structure of the bulk liquid at any T. This unique\nstring environment persists from the melting T upon cooling to the lowest T\nstudied in the vicinity of the mode-coupling temperature, and is explained by\nthe existence of rigid elongated cages. We also form a criterion based solely\non structural features of the local environment that allow the identification\nof particles with an increased propensity for mobility.",
        "positive": "Comparison between step strains and slow steady shear in a bubble raft: We report on a comparison between stress relaxations after an applied step\nstrain and stress relaxations during slow, continuous strain in a bubble raft.\nA bubble raft serves as a model two-dimensional foam and consists of a single\nlayer of bubbles on a water surface. For both step strains and continuous\nstrain, one observes periods of stress increase and decrease. Our focus is on\nthe distribution of stress decreases, or stress drops. The work is motivated by\napparent disagreements between quasistatic simulations of flowing foam and\nsimulations of continuous strain for foam. Quasistatic simulations have\nreported larger average stress drops than the continuous strain case. Also,\nthere is evidence in quasistatic simulations for a general divergence of the\naverage size of the stress drops that only appears to occur in steady strain\nnear special values of the foam density. In this work, applied step strains are\nused as an approximation to quasistatic simulations. We find general agreement\nin the dependence of the average stress drop on rate of strain, but we do not\nobserve evidence for a divergence of the average stress drop."
    },
    {
        "anchor": "Thermodynamic perturbation theory for self assembling mixtures of multi\n  - patch colloids and colloids with spherically symmetric attractions: In this paper we extend our previous theory [B. D. Marshall and W.G. Chapman,\nJ. Chem. Phys. 139, 104904 (2013)] for mixtures of single patch colloids (p\ncolloids) and colloids with spherically symmetric attractions (s colloids) to\nthe case that the p colloids can have multiple patches. The theory is then\napplied to the case of a binary mixture of bi-functional p colloids which have\nan A and B type patch and s colloids which are not attracted to other s\ncolloids and are attracted to only patch A on the p colloids. This mixture\nreversibly self assembles into both colloidal star molecules, where the s\ncolloid is the articulation segment and the p colloids form the arms, and free\nchains composed of only p colloids. It is shown that temperature, density,\ncomposition and relative attractive strengths can all be varied to manipulate\nthe number of arms per colloidal star molecule, average arm length and the\nfraction of chains (free chains + arms) which are star arms.",
        "positive": "Origin of Scaling Behavior of Protein Packing Density: A Sequential\n  Monte Carlo Study of Compact Long Chain Polymers: Single domain proteins are thought to be tightly packed. The introduction of\nvoids by mutations is often regarded as destabilizing. In this study we show\nthat packing density for single domain proteins decreases with chain length. We\nfind that the radius of gyration provides poor description of protein packing\nbut the alpha contact number we introduce here characterize proteins well. We\nfurther demonstrate that protein-like scaling relationship between packing\ndensity and chain length is observed in off-lattice self-avoiding walks. A key\nproblem in studying compact chain polymer is the attrition problem: It is\ndifficult to generate independent samples of compact long self-avoiding walks.\nWe develop an algorithm based on the framework of sequential Monte Carlo and\nsucceed in generating populations of compact long chain off-lattice polymers up\nto length $N=2,000$. Results based on analysis of these chain polymers suggest\nthat maintaining high packing density is only characteristic of short chain\nproteins. We found that the scaling behavior of packing density with chain\nlength of proteins is a generic feature of random polymers satisfying loose\nconstraint in compactness. We conclude that proteins are not optimized by\nevolution to eliminate packing voids."
    },
    {
        "anchor": "A driven two-dimensional granular gas with Coulomb friction: We study a homogeneously driven granular gas of inelastic hard particles with\nrough surfaces subject to Coulomb friction. The stationary state as well as the\nfull dynamic evolution of the translational and rotational granular\ntemperatures are investigated as a function of the three parameters of the\nfriction model. Four levels of approximation to the (velocity-dependent)\ntangential restitution are introduced and used to calculate translational and\nrotational temperatures in a mean field theory. When comparing these\ntheoretical results to numerical simulations of a randomly driven mono-layer of\nparticles subject to Coulomb friction, we find that already the simplest model\nleads to qualitative agreement, but only the full Coulomb friction model is\nable to reproduce/predict the simulation results quantitatively for all\nmagnitudes of friction. In addition, the theory predicts two relaxation times\nfor the decay to the stationary state. One of them corresponds to the\nequilibration between the translational and rotational degrees of freedom. The\nother one, which is slower in most cases, is the inverse of the common\nrelaxation rate of translational and rotational temperatures.",
        "positive": "Extreme congestion of microswimmers at a bottleneck constriction: When attracted by a stimulus (e. g. light), microswimmers can build up very\ndensely at a constriction and thus cause clogging. The micro-alga\n\\textit{Chlamydomonas Reinhardtii} is used here as a model system to study this\nphenomenon. Its negative phototaxis makes the algae swim away from a light\nsource and go through a microfabricated bottleneck-shaped constriction.\nSuccessive clogging events interspersed with bursts of algae are observed. A\npower law decrease is found to describe well the distribution of time lapses of\nblockages. Moreover, the evacuation time is found to increase when increasing\nthe swimming velocity. These results might be related to the phenomenology of\ncrowd dynamics and in particular what has been called the Faster is Slower\neffect in the dedicated literature. It also raises the question of the presence\nof tangential solid friction between motile cells densely packed that may\naccompany arches formation. Using the framework of crowd dynamics we analyze\nthe microswimmers behavior and in particular question the role of\nhydrodynamics."
    },
    {
        "anchor": "Phase separation of penetrable core mixtures: A two-component system of penetrable particles interacting via a gaussian\ncore potential is considered, which may serve as a crude model for binary\npolymer solutions. The pair structure and thermodynamic properties are\ncalculated within the random phase approximation (RPA) and the hypernetted\nchain (HNC) integral equation. The analytical RPA predictions are in\nsemi-quantitative agreement with the numerical solutions of the HNC\napproximation, which itself is very accurate for gaussian core systems. A\nfluid-fluid phase separation is predicted to occur for a broad range of\npotential parameters. The pair structure exhibits a nontrivial clustering\nbehaviour of the minority component. Similiar conclusions hold for the related\nmodel of parabolic core mixtures, which is frequently used in dissipative\nparticle dynamics (DPD) simulations.",
        "positive": "Water structure-forming capabilities are temperature shifted for\n  different models: A large number of water models exists for molecular simulations. They differ\nin the ability to reproduce specific features of real water instead of others,\nlike the correct temperature for the density maximum or the diffusion\ncoefficient. Past analysis mostly concentrated on ensemble quantities, while\nfew data was reported on the different microscopic behavior. Here, we compare\nseven widely used classical water models (SPC, SPC/E, TIP3P, TIP4P, TIP4P-Ew,\nTIP4P/2005 and TIP5P) in terms of their local structure-forming capabilities\nthrough hydrogen bonds for temperatures ranging from 210 K to 350 K by the\nintroduction of a set of order parameters taking into account the configuration\nof the second solvation shell. We found that all models share the same\nstructural pattern up to a temperature shift. When this shift is applied, all\nmodels overlap onto a master curve. Interestingly, increased stabilization of\nfully coordinated structures extending to at least two solvation shells is\nfound for models that are able to reproduce the correct position of the density\nmaximum. Our results provide a self-consistent atomic-level structural\ncomparison protocol, which can be of help in elucidating the influence of\ndifferent water models on protein structure and dynamics."
    },
    {
        "anchor": "Engineering single-polymer micelle shape using non-uniform spontaneous\n  surface curvature: Conventional micelles, composed of simple amphiphiles, exhibit only a few\nstandard morphologies, each characterized by its mean surface curvature set by\nthe amphiphiles. Here we demonstrate a rational design scheme to construct\nmicelles of more general shape from polymeric amphiphiles. We replace the many\namphiphiles of a conventional micelle by a single flexible, linear, block\ncopolymer chain containing two incompatible species arranged in multiple\nalternating segments. With suitable segment lengths, the chain exhibits a\ncondensed spherical configuration in solution, similar to conventional\nmicelles. Our design scheme posits that further shapes are attained by altering\nthe segment lengths. To assess the power of this scheme, we exhibit stable\nmicelles of horseshoe form using conventional bead-spring simulations in two\ndimensions. Modest changes in the segment lengths produce smooth changes in the\nmicelle's shape and stability.",
        "positive": "Low dose X-ray speckle visibility spectroscopy reveals nanoscale\n  dynamics in radiation sensitive ionic liquids: X-ray radiation damage provides a serious bottle neck for investigating\n{\\mu}s to s dynamics on nanometer length scales employing X-ray photon\ncorrelation spectroscopy. This limitation hinders the investigation of real\ntime dynamics in most soft matter and biological materials which can tolerate\nonly X-ray doses of kGy and below. Here, we show that this bottleneck can be\novercome by low dose X-ray speckle visibility spectroscopy. Employing X-ray\ndoses of 22 kGy to 438 kGy and analyzing the sparse speckle pattern of count\nrates as low as 6.7x10-3 per pixel we follow the slow nanoscale dynamics of an\nionic liquid (IL) at the glass transition. At the pre-peak of nanoscale order\nin the IL we observe complex dynamics upon approaching the glass transition\ntemperature TG with a freezing in of the alpha relaxation and a multitude of\nmilli-second local relaxations existing well below TG. We identify this fast\nrelaxation as being responsible for the increasing development of nanoscale\norder observed in ILs at temperatures below TG."
    },
    {
        "anchor": "Field exposed water in a nanopore: liquid or vapour?: We study the behavior of ambient temperature water under the combined effects\nof nanoscale confinement and applied electric field. Using molecular\nsimulations we analyze the thermodynamic causes of field-induced expansion at\nsome, and contraction at other conditions. Repulsion among parallel water\ndipoles and mild weakening of interactions between partially aligned water\nmolecules prove sufficient to destabilize the aqueous liquid phase in isobaric\nsystems in which all water molecules are permanently exposed to a uniform\nelectric field. At the same time, simulations reveal comparatively weak\nfield-induced perturbations of water structure upheld by flexible hydrogen\nbonding. In open systems with fixed chemical potential, these perturbations do\nnot suffice to offset attraction of water into the field; additional water is\ntypically driven from unperturbed bulk phase to the field-exposed region. In\ncontrast to recent theoretical predictions in the literature, our analysis and\nsimulations confirm that classical electrostriction characterizes usual\nelectrowetting behavior in nanoscale channels and nanoporous materials.",
        "positive": "Acoustic wave front reversal in a three-phase media: Acoustic wave front conjugation is studied in a sandy marine sediment that\ncontains air bubbles in its fluid fraction. The considered phase conjugation is\na four-wave nonlinear parametric sound interaction process caused by nonlinear\nbubble oscillations which are known to be dominant in acoustic nonlinear\ninteractions in three-phase marine sediments. Two various mechanisms of phase\nconjugation are studied. One of them is based on the stimulated Raman-type\nsound scattering on resonance bubble oscillations. The second one is associated\nwith sound interactions with bubble oscillations which frequencies are far from\nresonance bubble frequencies. Nonlinear equations to solve the wave-front\nconjugation problem are derived, expressions for acoustic wave amplitudes with\na reversed wave front are obtained and compared for various frequencies of the\nexcited bubble oscillations."
    },
    {
        "anchor": "Dynamics and Configurational Entropy in the LW Model for Supercooled\n  Orthoterphenyl: We study thermodynamic and dynamic properties of a rigid model of the fragile\nglass forming liquid orthoterphenyl. A system of N=343 molecules is considered\nin a wide range of densities and temperatures, reaching simulation times up to\n1 microsecond. Working within the inherent structures thermodynamic formalism,\nwe present results for the temperature and density dependence of the number,\ndepth and shape of the basins of the potential energy surface. We evaluate the\nconfigurational entropy of the system and we study the connection between\nthermodynamical and dynamical properties. We confirm that the temperature\ndependence of the configurational entropy and of the diffusion constant, as\nwell as the inverse of the characteristic structural relaxation time, are\nstrongly connected in supercooled states.",
        "positive": "Effective field theory approach to fluctuation-induced forces between\n  colloids at an interface: We discuss an effective field theory (EFT) approach to the computation of\nfluctuation-induced interactions between particles bound to a thermally\nfluctuating fluid surface controlled by surface tension. By describing\nparticles as points, EFT avoids computing functional integrals subject to\ndifficult constraints. Still, all information pertaining to particle size and\nshape is systematically restored by amending the surface Hamiltonian with a\nderivative expansion. The free energy is obtained as a cumulant expansion, for\nwhich straightforward techniques exist. We derive a complete description for\nrigid axisymmetric objects, which allows us to develop a full asymptotic\nexpansion in powers of the inverse distance for the pair interaction. We also\ndemonstrate by a few examples the efficiency with which multibody interactions\ncan be computed. Moreover, although the main advantage of the EFT approach lies\nin explicit computation, we discuss how one can infer certain features of cases\ninvolving flexible or anisotropic objects. The EFT description also permits a\nsystematic computation of ground-state surface-mediated interactions, which we\nillustrate with a few examples."
    },
    {
        "anchor": "Polymer Glass-Formation in Variable Dimension: We explore the nature of glass-formation in variable spatial dimensionality\n($d$) based on the generalized entropy theory, a synthesis of the Adam-Gibbs\nmodel with direct computation of the configurational entropy of polymer fluids\nusing an established statistical mechanical model. We find that structural\nrelaxation in the fluid state asymptotically becomes Arrhenius in the\n$d\\rightarrow\\infty$ limit and that the fluid transforms upon sufficient\ncooling above a critical dimension near $d=8$ into a dense amorphous state with\na finite positive residual configurational entropy. Direct computations of the\nisothermal compressibility and thermal expansion coefficient, taken to be\nphysical measures of packing frustration, demonstrate that these fluid\nproperties strongly correlate with the fragility of glass-formation.",
        "positive": "Continuum modeling of Soft Glassy Materials under shear: Soft Glassy Materials (SGM) consist in dense amorphous assemblies of\ncolloidal particles of multiple shapes, elasticity, and interactions, which\nconfer upon them solid-like properties at rest. They are ubiquitously\nencountered in modern engineering, including additive manufacturing, semi-solid\nflow cells, dip-coating, adhesive locomotion, where they are subjected to\ncomplex mechanical histories. Such processes often include a solid-to-liquid\ntransition induced by large enough shear, which results in complex transient\nphenomena such as non-monotonic stress responses, i.e., stress overshoot, and\nspatially heterogeneous flows, e.g., shear-banding or brittle failure. In the\npresent article, we propose a pedagogical introduction to a continuum model\nbased on a spatially-resolved fluidity approach that we recently introduced to\nrationalize shear-induced yielding in SGMs. Our model, which relies upon\nnon-local effects, quantitatively captures salient features associated with\nsuch complex flows, including the rate dependence of the stress overshoot, as\nwell as transient shear-banded flows together with nontrivial scaling laws for\nfluidization times. This approach offers a versatile framework to account for\nsubtle effects, such as avalanche-like phenomena, or the impact of boundary\nconditions, which we illustrate by including in our model the\nelasto-hydrodynamic slippage of soft particles compressed against solid\nsurfaces."
    },
    {
        "anchor": "Bulk and wetting phenomena in a colloidal mixture of hard spheres and\n  platelets: Density functional theory is used to study binary colloidal fluids consisting\nof hard spheres and thin platelets in their bulk and near a planar hard wall.\nThis system exhibits liquid-liquid coexistence of a phase that is rich in\nspheres (poor in platelets) and a phase that is poor in spheres (rich in\nplatelets). For the mixture near a planar hard wall, we find that the phase\nrich in spheres wets the wall completely upon approaching the liquid demixing\nbinodal from the sphere-poor phase, provided the concentration of the platelets\nis smaller than a threshold value which marks a first-order wetting transition\nat coexistence. No layering transitions are found in contrast to recent studies\non binary mixtures of spheres and non-adsorbing polymers or thin hard rods.",
        "positive": "Dynamical Eigenmodes of a Polymerized Membrane: We study the bead-spring model for a polymerized phantom membrane in the\noverdamped limit, which is the two-dimensional generalization of the well-known\nRouse model for polymers. We derive the {\\it exact} eigenmodes of the membrane\ndynamics (the \"Rouse modes\"). This allows us to obtain exact analytical\nexpressions for virtually any equilibrium or dynamical quantity for the\nmembrane. As examples we determine the radius of gyration, the mean square\ndisplacement of a tagged bead, and the autocorrelation function of the\ndifference vector between two tagged beads. Interestingly, even in the presence\nof tensile forces of any magnitude the Rouse modes remain the exact eigenmodes\nfor the membrane. With stronger forces the membrane becomes essentially flat,\nand does not get the opportunity to intersect itself; in such a situation our\nanalysis provides a useful and exactly soluble approach to the dynamics for a\nrealistic model flat membrane under tension."
    },
    {
        "anchor": "Dynamical Coarse-Graining of Highly Fluctuating Membranes under Shear\n  Flow: The effect of strong shear flow on highly fluctuating lamellar systems\nstabilized by intermembrane collisions via the Helfrich interaction is studied.\nAdvection enters the microscopic equation of motion for a single membrane via a\nnon-linear coupling. Upon coarse-graining the theory for a single bilayer up to\nthe length scale of the collision length, at which a hydrodynamic description\napplies, an additional dynamical coupling is generated which is of the form of\na wavevector-dependent tension that is non-linear in the applied shear rate.\nThis new term has consequences for the effects of strong flow on the stability\nand dynamics of lamellar surfactant phases.",
        "positive": "Asymptotics of the dispersion interaction: analytic benchmarks for van\n  der Waals energy functionals: We show that the usual sum of $R^{-6}$ contributions from elements separated\nby distance $R$ can give \\emph{qualitatively} wrong results for the\nelectromagnetically non-retarded van der Waals interaction between\nnon-overlapping bodies. This occurs for anisotropic nanostructures that have a\nzero electronic energy gap, such as nanowires, conducting nanotubes, and\nnano-layered systems including metals and graphene planes. In all these cases\nour analytic microscopic calculations give an interaction falling off with a\npower of separation different from the conventional value. We discuss\nimplications for van der Waals energy functionals. The new nanotube interaction\nmight be directly measurable at sub-micron separations."
    },
    {
        "anchor": "Simple deformation measures for Discrete elastic rods and ribbons: The Discrete elastic rod method (Bergou et al., 2008) is a numerical method\nfor simulating slender elastic bodies. It works by representing the center-line\nas a polygonal chain, attaching two perpendicular directors to each segment,\nand defining discrete stretching, bending and twisting deformation measures and\na discrete strain energy. Here, we investigate an alternative formulation of\nthis model based on a simpler definition of the discrete deformation measures.\nBoth formulations are equally consistent with the continuous rod model. Simple\nformulas for the first and second gradients of the discrete deformation\nmeasures are derived, making it easy to calculate the Hessian of the discrete\nstrain energy. A few numerical illustrations are given. The approach is also\nextended to inextensible ribbons described by the Wunderlich model, and both\nthe developability constraint and the dependence of the energy of the strain\ngradients are handled naturally.",
        "positive": "Generation of macroscopic pair-correlated atomic beams by four-wave\n  mixing in Bose-Einstein condensates: By colliding two Bose-Einstein condensates we have observed strong bosonic\nstimulation of the elastic scattering process. When a weak input beam was\napplied as a seed, it was amplified by a factor of 20. This large gain atomic\nfour-wave mixing resulted in the generation of two macroscopically occupied\npair-correlated atomic beams."
    },
    {
        "anchor": "Enhancement of solid-state proton NMR via SPINOE with laser-polarized\n  xenon: We have first successfully transferred the 129Xe polarization of natural\nisotopic composition to the proton of solid-state 1HCl via Spin\nPolarization-Induced Nuclear Overhauser Effect (SPINOE), by mixing the\nhyperpolarized 129Xe gas and the 1HCl gas and then cooling them to their\ncondensated state in a flow system. The solid-state enhanced factor of the NMR\nsignal of 6 for 1H was observed, and the equation of solid-state polarization\nenhancement via cross relaxation has also been theoretically deduced. Using\nthis equation, the theoretically calculated enhancement is in agreement with\nthe measured value within error. Also, this technique is maybe useful to\nestablish a solid state NMR quantum computer.",
        "positive": "Acoustic Bubble Dynamics in a Yield-Stress Fluids: Yield-stress fluids naturally trap small bubbles when their buoyancy applies\nan insufficient stress to induce local yielding of the material. Under acoustic\nexcitation, trapped bubbles can be driven into volumetric oscillations and\napply an additional local strain and stress that can trigger yielding and\nassist their release. In this paper we explore different regimes of microbubble\noscillation and translation driven by an ultrasound field in a model\nyield-stress fluid, a Carbopol microgel. We first analyse the linear bubble\noscillation dynamics to measure the local, high-frequency viscosity of the\nmaterial. We then use acoustic pressure gradients to induce bubble translation\nand examine the elastic part of the response of the material below yielding. We\nfind that, at moderate pressure amplitude, the additional stresses applied by\nvolumetric oscillations and acoustic radiation forces do not lead to any\ndetectable irreversible bubble motion. At high pressure amplitude, we observe\nnon-spherical shape oscillations that result in erratic bubble motion. The\nshape modes and critical pressures we observe differ from the predictions of a\nrecent model of shape oscillations in soft solids.Based on our findings, we\ndiscuss possible reasons for the lack of bubble release in Carbopol and suggest\nother systems in which ultrasound-assisted bubble rise may be observed."
    },
    {
        "anchor": "Boussinesq-like problems in discrete media: Vertical loads acting on the surface of a half-space made of discrete and\nelastic particles are supported by a network of force chains that changes with\nthe specific realization of the packing. These force chains can be transformed\ninto equivalent stress fields, but the obtained values are usually different to\nthose expected from the solution of the corresponding boundary value problem.\nIn this research the relationship between discrete and continuum approaches to\nBoussinesq-like problems is explored in the light of classical statistical\nmechanics. In principal directions, the anticipated statistical distributions\nof the extensive stress (\\textit{i.e.} the product of the stress by the volume)\nare exponential distributions for normal components and Laplace distributions\nfor shear components. The parameters scaling these distributions can be\nobtained from the solutions provided by continuum approaches in most of the\ncases. This has been validated through massive numerical simulation with the\ndiscrete element method. These results could be of interest in highly\nfragmented, faulted or heterogeneous media or for small length scales.",
        "positive": "Colloidal charge reversal: Dependence on the ionic size and the\n  electrolyte concentration: Extensive Monte Carlo simulations and scaling arguments are used to study the\ncolloidal charge reversal. The critical colloidal surface charge density\n$\\sigma_c$ at which the reversal first appears is found to depend strongly on\nthe ionic size. We find that $\\sigma_c$ has an inflection point as a function\nof the electrolyte concentration. The width of the plateau region in the\nvicinity of the inflection point depends on the temperature and the ionic\nradius $a$. In agreement with the theoretical predictions it is found that the\ncritical colloidal charge above which the electrophoretic mobility becomes\nreversed diverges as $Z_c \\sim 1/a^2$ in the limit $a \\to 0$."
    },
    {
        "anchor": "Two-Dimensional Melting of a Crystal of Ferrofluid Spikes: We report the observation of the transition from an ordered solid-like phase\nto a disordered liquid-like phase of a lattice of spikes on a ferrofluid\nsurface submitted to horizontal sinusoidal vibrations. The melting transition\noccurs for a critical spike displacement which is experimentally found to\nfollow the Lindemann criterion, for two different lattice topologies (hexagonal\nand square) and over a wide range of lattice wavelengths. An intermediate\nhexatic-like phase between the solid and isotropic liquid phases is also\nobserved and characterized by standard correlation functions. This dissipative\nout-of-equilibrium system exhibits strong similarities with 2D melting in\nsolid-state physics.",
        "positive": "Fractals from genomes: exact solutions of a biology-inspired problem: This is a review of a set of recent papers with some new data added. After a\nbrief biological introduction a visualization scheme of the string composition\nof long DNA sequences, in particular, of bacterial complete genomes, will be\ndescribed. This scheme leads to a class of self-similar and self-overlapping\nfractals in the limit of infinitely long constotuent strings. The calculation\nof their exact dimensions and the counting of true and redundant avoided\nstrings at different string lengths turn out to be one and the same problem. We\ngive exact solution of the problem using two independent methods: the\nGoulden-Jackson cluster method in combinatorics and the method of formal\nlanguage theory."
    },
    {
        "anchor": "Slow dynamics, dynamic heterogeneities, and fragility of supercooled\n  liquids confined in random media: Using molecular dynamics simulations, we study the slow dynamics of\nsupercooled liquids confined in a random matrix of immobile obstacles. We study\nthe dynamical crossover from glass-like to Lorentz-gas-like behavior in terms\nof the density correlation function, the mean square displacement, the\nnonlinear dynamic susceptibility, the non-Gaussian parameter, and the\nfragility. Cooperative and spatially heterogeneous dynamics are suppressed as\nthe obstacle density increases, which lead to the more Arrhenius-like behavior\nin the temperature dependence of the relaxation time. Our findings are\nqualitatively consistent with the results of recent experimental and numerical\nstudies for various classes of spatially heterogeneous systems. We also\ninvestigate the dependence of the dynamics of mobile particles on the protocol\nto generate the random matrix. A reentrant transition from the arrested phase\nto the liquid phase as the mobile particle density {\\it increases} is observed\nfor a class of protocols. This reentrance is explained in terms of the\ndistribution of the volume of the voids that are available to the mobile\nparticles.",
        "positive": "Surface waves in a deformed isotropic hyperelastic material subject to\n  an isotropic internal constraint: An isotropic elastic half space is prestrained so that two of the principal\naxes of strain lie in the bounding plane, which itself remains free of\ntraction. The material is subject to an isotropic constraint of arbitrary\nnature. A surface wave is propagated sinusoidally along the bounding surface in\nthe direction of a principal axis of strain and decays away from the surface.\nThe exact secular equation is derived by a direct method for such a principal\nsurface wave; it is cubic in a quantity whose square is linearly related to the\nsquared wave speed. For the prestrained material, replacing the squared wave\nspeed by zero gives an explicit bifurcation, or stability, criterion.\nConditions on the existence and uniqueness of surface waves are given. The\nbifurcation criterion is derived for specific strain energies in the case of\nfour isotropic constraints: those of incompressibility, Bell, constant area,\nand Ericksen. In each case investigated, the bifurcation criterion is found to\nbe of a universal nature in that it depends only on the principal stretches,\nnot on the material constants. Some results related to the surface stability of\narterial wall mechanics are also presented."
    },
    {
        "anchor": "Active transport in a channel: stabilisation by flow or thermodynamics: Recent experiments on active materials, such as dense bacterial suspensions\nand microtubule-kinesin motor mixtures, show a promising potential for\nachieving self-sustained flows. However, to develop active microfluidics it is\nnecessary to understand the behaviour of active systems confined to channels.\nTherefore here we use continuum simulations to investigate the behaviour of\nactive fluids in a two-dimensional channel. Motivated by the fact that most\nexperimental systems show no ordering in the absence of activity, we\nconcentrate on temperatures where there is no nematic order in the passive\nsystem, so that any nematic order is induced by the active flow. We\nsystematically analyze the results, identify several different stable flow\nstates, provide a phase diagram and show that the key parameters controlling\nthe flow are the ratio of channel width to the length scale of active flow\nvortices, and whether the system is flow aligning or flow tumbling.",
        "positive": "Dynamic Clustering of Active Rings: A collection of rings made of active Brownian particles (ABPs) for different\npacking fractions and activities is investigated using computer simulations. We\nshow that active rings display an emergent dynamic clustering instead of the\nconventional motility-induced phase separation (MIPS) as in the case of\ncollection of ABPs. Surprisingly, increasing packing fraction of rings exhibits\na non-monotonicity in the dynamics due to the formation of a large number of\nsmall clusters. The conformational fluctuations of the polymers suppress the\nusual MIPS exhibited by ABPs. Our findings demonstrate how the motion of a\ncollection of rings is influenced by the interplay of activity, topology, and\nconnectivity."
    },
    {
        "anchor": "Homotopy classification of knotted defects in ordered media: We give a homotopy classification of the global defects in ordered media, and\nexplain it via the example of biaxial nematic liquid crystals, i.e., systems\nwhere the order parameter space is the quotient of the $3$-sphere $S^3$ by the\nquaternion group $Q$. As our mathematical model we consider continuous maps\nfrom complements of spatial graphs to the space $S^3/Q$ modulo a certain\nequivalence relation, and find that the equivalence classes are enumerated by\nthe six subgroups of $Q$. Through monodromy around meridional loops, the edges\nof our spatial graphs are marked by conjugacy classes of $Q$; once we pass to\nplanar diagrams, these labels can be refined to elements of $Q$ associated to\neach arc. The same classification scheme applies not only in the case of $Q$\nbut also to arbitrary groups.",
        "positive": "Flexibility Induced Motion Transition of Active Filament: Rotation\n  without Long-range Hydrodynamic Interaction: We investigate the motion of active semiflexible filament with shape\nkinematics and hydrodynamic interaction including. Three types of filament\nmotion are found: Translation, snaking and rotation. Change of flexibility will\ninduce instability of shape kinematics and further result in asymmetry of shape\nkinematics respect to the motion of mass center, which are responsible to a\ncontinuous-like transition from translation to snaking and a first-order-like\ntransition from snaking to rotation, respectively. Of particular interest, we\nfind that long-range hydrodynamic interaction is not necessary for filament\nrotation, but can enhance remarkably the parameter region for its appearance.\nThis finding may provide an evidence that the experimentally found collective\nrotation of active filaments is more likely to arise from the individual\nproperty even without the long-range hydrodynamic interaction."
    },
    {
        "anchor": "Electrical Conductivity of Nanoscale Hydrophobic Porous Media: Surface\n  Charge Density and Heterogeneous Pore Structure: Electrical conductivity is an inherent property of a hydrophobic porous media\n(HPM) and has critical applications. This research aims to provide a solution\nfor predicting the electrical conductivity of nanoscale HPM with heterogeneous\npore structure. Molecular dynamics (MD) simulations are compared with the\nmodified Poisson-Boltzmann (MPB) model for understanding ionic charge density\ndistributions in nanopores. The effective medium approximation (EMA)\nparticipates in calculating the effective conductance and conductivity of the\nnanoscale HPM. The results show that the surface charge density affects the\nionic density profiles in the hydrophobic nanopores. As the pore size\nincreases, the conductance increases. As the molarity of the aqueous\nelectrolyte solution (AES) decreases, the conductance decreases. A phenomenon\nrelated to the conductance saturation occurred when the molarity of AES is very\nlow. The effective conductance of an HPM increase as the coordination number\nincreases. Finally, based on the calculated effective conductance and the\nheterogeneous pore structure parameters, the electrical conductivity of a\nnanoscale HPM is calculated.",
        "positive": "Composite material in the sea urchin Cidaris rugosa: ordered and\n  disordered micron-scale bicontinuous geometries: The sponge-like biomineralised calcite materials found in echinoderm\nskeletons are of interest in terms of both structure formation and biological\nfunction. Despite their crystalline atomic structure, they exhibit curved\ninterfaces that have been related to known triply-periodic minimal surfaces.\nHere, we investigate the endoskeleton of the sea urchin Cidaris rugosa that has\nlong been known to form a microstructure related to the Primitive surface.\nUsing X-ray tomography, we find that the endoskeleton is organised as a\ncomposite material consisting of domains of bicontinuous microstructures with\ndifferent structural properties. We describe, for the first time, the\nco-occurrence of ordered Primitive and Diamond structures and of a disordered\nstructure within a single skeletal plate. We show that these structures can be\ndistinguished by structural properties including solid volume fraction,\ntrabeculae width, and to a lesser extent, interface area and mean curvature. In\ndoing so, we present a robust method that extracts interface areas and\ncurvature integrals from voxelized datasets using the Steiner polynomial for\nparallel body volumes. We discuss these very large scale bicontinuous\nstructures in the context of their function, formation, and evolution."
    },
    {
        "anchor": "Mechanical stretching of amyloid Abeta11-42 fibrils using steered\n  molecular dynamics: Mechanical strength of amyloid beta fibrils has been known to be correlated\nwith neuronal cell death. Here, we resorted to steered molecular dynamics (SMD)\nsimulations to mechanically stretch a single S-shape amyloid beta Abeta11-42\ndodecamer fibril in vacuum. It was found that the weakest sites at which the\nfibril was ruptured due to mechanical extension were exclusively at the\ninterfaces of alanine and glutamic acid distributed throughout the fibril. It\nwas also revealed that the free energy required to unfold the fibril to form a\nlong linear conformation is equivalent to ~ 210 eV, being several thousand\ntimes larger than thermal voltage at room temperature. As a consequence, within\nsolution a larger free energy is needed for such a maximal stretching based on\nthe fact that amyloid beta fibrils are structurally more stable in solution due\nto the interplay between their hydrophobic cores and solution's entropy.",
        "positive": "Contacts Dynamics Reveals Widom Lines for Jamming: We experimentally study the vicinity of the Jamming transition by\ninvestigating the statics and the dynamics of the contact network of an\nhorizontally shaken bi-disperse packing of photo-elastic discs. Compressing the\npacking very slowly, while maintaining a mechanical excitation, yields a\ngranular glass, namely a frozen structure of vibrating grains. In this glass\nphase, we observe a remarkable dynamics of the contact network, which exhibits\nstrong dynamical heterogeneities. Such heterogeneities are maximum at a packing\nfraction $\\phi^*$, \\emph{distinct} and smaller than the jamming packing\nfraction $\\phi_J$, which is indicated by the abrupt variation of the average\nnumber of contact per particle. We demonstrate that the two cross-overs, one\nfor the maximum dynamical heterogeneity, and the other for static jamming,\nconverge at point J in the zero mechanical excitation limit, a behavior\nreminiscent of the Widom lines in the supercritical phase of a second order\ncritical point. Our findings are discussed in the light of recent numerical and\ntheoretical studies of thermal soft spheres."
    },
    {
        "anchor": "Effects of Poly(styrene/pentafluorostyrene-block-vinylpyrrolidone)\n  Amphiphilic Kinetic Hydrate Inhibitors on the Dynamic Viscosity of Methane\n  Hydrate Systems at High-Pressure Driving Forces: Reversible addition-fragmentation chain-transfer polymerization with a\nswitchable chain-transfer agent was employed to synthesize amphiphilic block\ncopolymers poly(styrene-b-vinylpyrrolidone) and\npoly(pentafluorostyrene-b-vinylpyrrolidone) at 10 wt.% hydrophobic content as\nkinetic hydrate inhibitors for methane hydrates. The dynamic viscosity of\nmethane hydrate slurries was measured in a high-pressure rheometer up to 15\nMPag. At 700 ppm of additives in aqueous media, the relative time for slurries\nto grow to 200 mPa s was 2.2-2.4 times longer than water reference values for\nthe block copolymers. In contrast, it was only 1.3 for the\npoly(vinylpyrrolidone) homopolymer, demonstrating a reduced tendency for\nhydrate particle adhesion in block copolymer solutions. By increasing the\nconcentration to 7000 ppm, however, the relative time only increased to\n2.6-2.7. On the other hand, a block copolymer with 5 wt.%\npoly(pentafluorostyrene) block at 7000 ppm reached 3.5, which may indicate that\nthe optimal hydrophobic content differs for each amphiphilic polymer and\ndepends on monomer selection. No significant effect of polymer aggregation on\nhydrate growth was observed for the copolymers used in this study, which had\nthe same hydrophobic percentage and molecular weights between 10,000 and 40,000\ng/mol.",
        "positive": "Tuning energy dissipation via topologically electro-convoluted\n  lipid-membrane boundary layers: It was recently discovered that friction between surfaces bearing\nphosphatidylcholine (PC) lipid bilayers can be increased by two orders of\nmagnitude or more via an externally-applied electric field, and that this\nincrease is fully reversible when the field is switched off. While this\nstriking effect holds promising application potential, its molecular origin\nremains unknown due to difficulty in experimentally probing confined membrane\nstructure at a molecular level. Our earlier molecular dynamics simulations\nrevealed the equilibrium electroporated structure of such confined lipid\nmembranes under an electric field; here we extend this approach to study the\nassociated sliding friction between two solid surfaces across such PC bilayers.\nWe identify the enhanced friction in the field as arising from membrane\nundulations due to the electroporation; this leads to some dehydration at the\nlipid-water interfaces, leading to closer contact and thus increased attraction\nbetween the zwitterionic headgroups, which results in increased frictional\ndissipation between the bilayers as they slide past each other. Additionally,\nthe electric field facilitates formation of lipid bridges spanning the\nintersurface gap; at the sliding velocities of the experiments, these bridges\nincrease the friction by topologically-forcing the slip-plane to pass through\nthe acyl tail-tail interface, associated with higher dissipation during\nsliding. Our results account quantitatively for the experimentally-observed\nelectro-modulated friction with boundary lipid bilayers, and indicate more\ngenerally how they may affect interactions between contacting surfaces, where\nhigh local transverse fields may be ubiquitous."
    },
    {
        "anchor": "Perturbation Method in the Analysis of thin deformed Films and the\n  possible Application: The perturbation method for the analysis of thin, manifestly deformed films\nis given. The application of the method the excitons in the film has shown that\nthose have the effective mass essentially depending on the propagation\ndirection. The effects of a mechanical deformation of the film were\ninvestigated. It was concluded that the film could serve as an emiter of\ninfrared radiation if the mechanical deformation periodically changes in time.",
        "positive": "Interaction of Spherical Colloidal Particles in Nematic Media with\n  Degenerate Planar Anchoring: The interaction between two spherical colloidal particles with degenerate\nplanar anchoring in a nematic media is studied by numerically minimizing the\nbulk Landau-de Gennes and surface energy using a finite element method. We find\nthat the energy achieves its global minimum when the particles are in close\ncontact and making an angle $\\theta = 28^\\circ \\pm 2$ with respect to the bulk\nnematic director, in agreement with the experiments. Although the quadrupolar\nstructure of the director field is preserved in the majority of configurations,\nwe show that for smaller orientation angles and at smaller inter-particle\nseparations, the axial symmetry of the topological defect-pairs is continuously\nbroken, resulting in the emergence of an attractive interaction."
    },
    {
        "anchor": "Observation of Liquid Glass in Molecular Dynamics Simulations: Molecular anisotropy plays an important role in the glass transition of a\nliquid. Recently, a novel glass state has been discovered by optical microscopy\nexperiments on suspensions of ellipsoidal colloids. 'Liquid glass' is a\ndisordered analog of a nematic liquid crystal, where rotation motion is\nhindered but particles diffuse freely. Global nematic order is suppressed as\nclusters of aligned particles intertwine. We perform Brownian dynamics\nsimulations to test the structure and dynamics of a dense system of soft\nellipsoidal particles. As seen in experiments and in accordance with\npredictions from mode coupling theory, on the time scale of our simulations\nrotation motion is frozen but translation motion persists in liquid glass.\nAnalyses of the dynamic structure functions for translation and rotation\ncorroborates the presence of two separate glass transitions for rotation and\ntranslation, respectively. Even though the equilibrium state should be a\nnematic, aligned structures remain small and orientational order rapidly decays\nwith increasing size. Long-wavelength fluctuations are remnants of the\nisotropic-nematic transition.",
        "positive": "Three-Dimensional Yielding in Anisotropic Materials: Validation of Hill\n  Criterion: Yielding transition in isotropic soft materials under superposition of\northogonal deformation fields is known to follow von Mises criterion. However,\nin anisotropic soft materials von Mises criterion fails owing to preferred\ndirections associated with the system. In this work we study a model\nanisotropic yield stress system: electrorheological (ER) fluids that show\nstructure formation in the direction of electric field. We subject the ER\nfluids to superposition of orthogonal stress fields that leads to different\nyield stress values. We obtain a yielding state diagram by plotting normalized\nrotational shear stress against normalized radial shear stress corresponding to\nyield point for a given electric field. Remarkably, the state diagram validates\nthe Hill yielding criterion, which is a general yielding criterion for\nmaterials having anisotropy along three orthogonal directions, originally\ndeveloped for metallic systems. Validation of Hill criterion suggests the\nuniversality of its application to anisotropic systems including conventional\nanisotropic soft materials having yield stress."
    },
    {
        "anchor": "Unzipping DNA by force: thermodynamics and finite size behaviour: We discuss the thermodynamic behaviour near the force induced unzipping\ntransition of a double stranded DNA in two different ensembles. The Y-fork is\nidentified as the coexisting phases in the fixed distance ensemble. From finite\nsize scaling of thermodynamic quantities like the extensibility, the length of\nthe unzipped segment of a Y-fork, the phase diagram can be recovered. We\nsuggest that such procedures could be used to obtain the thermodynamic phase\ndiagram from experiments on finite length DNA.",
        "positive": "The conformation of a semiflexible filament in a quenched random\n  potential: Motivated by the observation of the storage of excess elastic free energy -\n(prestress) -- in cross linked semiflexible networks, we consider the problem\nof the conformational statistics of a single semiflexible polymer in a quenched\nrandom potential. The random potential, which represents the effect of cross\nlinking to other filaments is assumed to have a finite correlation length $\\xi$\nand mean strength $V_{0}$. We examine statistical distribution of curvature in\nfilament with thermal persistence length $\\ell_{P}$ and length $L_0$ in the\nlimit that $\\ell_{P} \\gg L_0$. We compare our theoretical predictions to finite\nelement Brownian dynamics simulations. Lastly we comment on the validity of\nreplica field techniques in addressing these questions."
    },
    {
        "anchor": "Solidification in soft-core fluids: disordered solids from fast\n  solidification fronts: Using dynamical density functional theory we calculate the speed of\nsolidification fronts advancing into a quenched two-dimensional model fluid of\nsoft-core particles. We find that solidification fronts can advance via two\ndifferent mechanisms, depending on the depth of the quench. For shallow\nquenches, the front propagation is via a nonlinear mechanism. For deep\nquenches, front propagation is governed by a linear mechanism and in this\nregime we are able to determine the front speed via a marginal stability\nanalysis. We find that the density modulations generated behind the advancing\nfront have a characteristic scale that differs from the wavelength of the\ndensity modulation in thermodynamic equilibrium, i.e., the spacing between the\ncrystal planes in an equilibrium crystal. This leads to the subsequent\ndevelopment of disorder in the solids that are formed. For the one-component\nfluid, the particles are able to rearrange to form a well-ordered crystal, with\nfew defects. However, solidification fronts in a binary mixture exhibiting\ncrystalline phases with square and hexagonal ordering generate solids that are\nunable to rearrange after the passage of the solidification front and a\nsignificant amount of disorder remains in the system.",
        "positive": "Capillary-induced interactions between colloids at an interface: Within a general framework we study the effective, deformation-induced\ninteraction between two colloids trapped at a fluid interface. As an\napplication, we consider the interface deformation owing to the electrostatic\nfield of charged colloids. The effective interaction is attractive and\novercomes the direct electrostatic repulsion at large separations if the system\nis not mechanically isolated. Otherwise, a net attraction seems possible only\nfor large enough colloidal charges."
    },
    {
        "anchor": "Anomalous behavior of trapping in extended dendrimers with a perfect\n  trap: Compact and extended dendrimers are two important classes of dendritic\npolymers. The impact of the underlying structure of compact dendrimers on\ndynamical processes has been much studied, yet the relation between the\ndynamical and structural properties of extended dendrimers remains not well\nunderstood. In this paper, we study the trapping problem in extended dendrimers\nwith generation-dependent segment lengths, which is different from that of\ncompact dendrimers where the length of the linear segments is fixed. We first\nconsider a particular case that the deep trap is located at the central node,\nand derive an exact formula for the average trapping time (ATT) defined as the\naverage of the source-to-trap mean first passage time over all starting points.\nThen, using the obtained result we deduce a closed-form expression for the ATT\nto an arbitrary trap node, based on which we further obtain an explicit\nsolution to the ATT corresponding to the trapping issue with the trap uniformly\ndistributed in the polymer systems. We show that the trap location has a\nsubstantial influence on the trapping efficiency measured by the ATT, which\nincreases with the shortest distance from the trap to the central node, a\nphenomenon similar to that for compact dendrimers. In contrast to this\nresemblance, the leading terms of ATTs for the three trapping problems differ\ndrastically between extended and compact dendrimers, with the trapping\nprocesses in the extended dendrimers being less efficient than in compact\ndendrimers.",
        "positive": "The unusual glassy dynamics of confluent epithelial monolayer is nearly\n  ideal for mode-coupling theory: Glassy dynamics in confluent epithelial monolayers are crucial for wound\nhealing, embryogenesis, cancer progression, etc. Despite many experimental and\nsimulation results, not much theoretical study exists due to the complex nature\nof the systems leading to unusual properties such as subArrhenius relaxation.\nOn the other hand, the mode-coupling theory (MCT) of glass only requires the\nstatic structure to give the dynamics. We have simulated the equilibrium Vertex\nmodel of the epithelial monolayers, computed the radial distribution function\nnumerically, obtained the static structure factor via Fourier transform,\nprovided the data as input to MCT, calculated the dynamics numerically, and\ncompared that with the dynamics obtained from simulation. Except the spurious\nnon-ergodicity transition of MCT, we find remarkable agreement with the other\ntheoretical predictions in the sub-Arrhenius regime of the system. The\nrelaxation time increases as a power law, the exponent and the prefactor remain\nconstant, the auto-correlation function shows time-temperature superposition,\nand the dynamics is sub-Arrhenius. In fact, confluent systems in this regime\nare probably the first known ideal candidate without quenched disorder for MCT.\nThis discovery brings about two seemingly disparate fields together, provides\ncrucial insights into the dynamics of confluent systems, and promises a more\nprofound understanding of the theory."
    },
    {
        "anchor": "Mobility Measurements Probe Conformational Changes in Membrane Proteins\n  due to Tension: The function of membrane-embedded proteins such as ion channels depends\ncrucially on their conformation. We demonstrate how conformational changes in\nasymmetric membrane proteins may be inferred from measurements of their\ndiffusion. Such proteins cause local deformations in the membrane, which induce\nan extra hydrodynamic drag on the protein. Using membrane tension to control\nthe magnitude of the deformations and hence the drag, measurements of\ndiffusivity can be used to infer--- via an elastic model of the protein--- how\nconformation is changed by tension. Motivated by recent experimental results\n[Quemeneur et al., Proc. Natl. Acad. Sci. USA, 111 5083 (2014)] we focus on\nKvAP, a voltage-gated potassium channel. The conformation of KvAP is found to\nchange considerably due to tension, with its `walls', where the protein meets\nthe membrane, undergoing significant angular strains. The torsional stiffness\nis determined to be 26.8 kT at room temperature. This has implications for both\nthe structure and function of such proteins in the environment of a\ntension-bearing membrane.",
        "positive": "Do all liquids become strongly correlating at high pressure?: We present molecular dynamics simulations studying the influence of pressure\non the correlation between the constant-volume thermal equilibrium fluctuations\nof virial W and potential energy U, focusing on liquids that are not strongly\ncorrelating at low pressure, i.e., do not have a WU correlation coefficient\nabove 0.9. The systems studied are the two hydrogen-bonded liquids GROMOS\nmethanol and TIT5P water, the ionic liquid defined by a united-atom model of\nthe 1-butyl-3-methyl-imidazolium nitrate and, for reference, the standard\nsingle-component Lennard-Jones liquid. The simulations were performed for\npressures varying from 0 GPa to 10 GPa. For all systems studied we find that\nthe virial / potential energy correlation increases with increasing pressure.\nThis suggests that if crystallization is avoided, all liquids become strongly\ncorrelating at sufficiently high pressure."
    },
    {
        "anchor": "From Compact to Open Clusters in Systems with Competing Interactions: Colloidal particles, amphiphiles, and functionalized nanoparticles are\nexamples of systems that frequently exhibit short-range attractions coupled\nwith long-range repulsions. In this work, we observe striking differences in\nthe dynamics of self-assembled clusters that form in a simple isotropic model\nof such systems when the strength of attraction is varied. We find that while\nattraction-dominated particles self-assemble into compact clusters with\nproperties similar to micelles formed by amphiphilic molecules,\nrepulsion-dominated particles self-assemble into open clusters which have much\nshorter life-times. There is also a significantly different dependence of the\nsolution osmotic pressure versus composition: formation of compact clusters\ncauses a decrease in the pressure vs. density slope, while formation of open\nclusters does not effect the pressure. This thermodynamic quantity turns out to\nbe much more sensitive in picking out different clustering characteristics than\nthe overall aggregation curves or cluster shapes. Our results have significant\nimplications in developing design principles for stable cluster self-assembly\nand detection in both laboratory settings and in computer simulations.",
        "positive": "Variational approximation method for the long-range force transmission\n  in biopolymer gels: The variational principle of minimum free energy (MFEVP) has been widely used\nin the study of soft matter statics. MFEVP can be used not only to derive\nequilibrium equations (including both bulk equations and boundary conditions),\nbut also to develop direct variational methods (such as Ritz method) to find\napproximate solutions to these equilibrium equations. In this work, we applied\nthese variational methods to study long-range force transmission in nonlinear\nelastic biopolymer gels. We showed that the slow decay of cell-induced\ndisplacements measured experimentally for fibroblast spheroids in\nthree-dimensional fibrin gels can be well explained by variational\napproximations based on the three-chain model of biopolymer gels."
    },
    {
        "anchor": "Random Loose Packing in Granular Matter: We introduce and simulate a two dimensional probabilistic model of granular\nmatter at vanishing pressure. The model exhibits a perfectly sharp random loose\npacking density, a phenomenon that should be verifiable for real granular\nmatter.",
        "positive": "Linear and angular motion of self-diffusiophoretic Janus particles: We theoretically study the active motion of self-diffusiophoretic Janus\nparticles (JPs) using the Onsager-Casimir reciprocal relations. The linear and\nangular velocity of a single JP are shown to respectively result from a\ncoupling of electrochemical forces to the fluid flow fields induced by a force\nand torque on the JP. A model calculation is provided for half-capped JPs\ncatalysing a chemical reaction of solutes at their surface, by reducing the\ncontinuity equations of the reacting solutes to Poisson equations for the\ncorresponding electrochemical fields. We find that an anisotropic chemical\nactivity alone is enough to give rise to active linear motion of a JP, whereas\nactive rotation only occurs if the JP is not axisymmetric. In the absence of\nspecific interactions with the solutes, the active linear velocity of the JP is\nshown to be related to the stoichiometrically weighted sum of the friction\ncoefficients (or hydrodynamic radii) of the reacting solutes. Our reciprocal\ntreatment further suggests that a specific interaction with the solutes is\nrequired to observe far-field diffusiophoretic interactions between JPs, which\nrely on an interfacial solute excess at the JP surface. Most notably, our\napproach applies beyond the boundary-layer approximation and accounts for both\nthe diffusio- and electrophoretic nature of active motion."
    },
    {
        "anchor": "Coarse-grained cellular automaton simulation of spherulite growth during\n  polymer crystallization: The work introduces a 3D cellular automaton model for the spatial and\ncrystallographic prediction of spherulite growth phenomena in polymers at the\nmesoscopic scale. The automaton is discrete in time, real space, and\norientation space. The kinetics is formulated according to the\nHoffman-Lauritzen secondary surface nucleation and growth theory for spherulite\nexpansion. It is used to calculate the switching probability of each grid point\nas a function of its previous state and the state of the neighboring grid\npoints. The actual switching decision is made by evaluating the local switching\nprobability using a Monte Carlo step. The growth rule is scaled by the ratio of\nthe local and the maximum interface energies, the local and maximum occurring\nGibbs free energy of transformation, the local and maximum occurring\ntemperature, and by the spacing of the grid points. The use of experimental\ninput data provides a real time and space scale.",
        "positive": "Oscillatory, non-progressing flows induce directed cell motion: We present a deformation-dependent propulsion phenomenon for soft particles\nsuch as cells in microchannels. It is based on a broken time reversal symmetry\ngenerated by a fast forward and slow backward motion of a fluid which does not\nprogress on average. In both sections, soft particles deform differently and\nthus progress relatively to the liquid. We demonstrate this by using\nLattice-Boltzmann simulations of ubiquitous red blood cells in microchannels,\nas well as simulations for capsules and minimal soft tissue models in unbounded\nPoiseuille flows. The propulsion of the soft particles depends besides the\noscillation asymmetry on their size, deformation type and elasticity. This is\nalso demonstrated by analytical calculations for a minimal model. Our findings\nmay stimulate a rethinking of particle sorting methods. For example, healthy\nand malignant cells often differ in their elasticity. With the proposed method,\nseveral cell types with different deformability can be separated simultaneously\nwithout labeling or obstacles in a microfluidic device."
    },
    {
        "anchor": "Combining mechanical and chemical effects in the deformation and failure\n  of a cylindrical electrode particle in a Li-ion battery: A general framework to study the mechanical behaviour of a cylindrical\nsilicon anode particle in a lithium ion battery as it undergoes lithiation is\npresented. The two-way coupling between stress and concentration of lithium in\nsilicon, including the possibility of plastic deformation, is taken into\naccount and two particular cases are considered. First, the cylindrical\nparticle is assumed to be free of surface traction and second, the axial\ndeformation of the cylinder is prevented. In both cases plastic stretches\ndevelop through the entire cylinder and not just near the surface as is\ncommonly found in spherical anode particles. It is shown that the stress\nevolution depends both on the lithiation rate and the external constraints.\nFurthermore, as the cylinder expands during lithiation it can develop a\ncompressive axial stress large enough to induce buckling, which in turn may\nlead to mechanical failure. An explicit criterion for swelling-induced buckling\nobtained as a modification of the classical Euler buckling criterion shows the\ncompetition between the stabilising effect of radius increase and the\ndestabilising effect of axial stress.",
        "positive": "Description of interfaces of fluid-tethered chains: advances in density\n  functional theories and off-lattice computer simulations: Many objects of nanoscopic dimensions involve fluid-tethered chain\ninterfaces. These systems are of interest for basic science and for several\napplications, in particular for design of nanodevices for specific purposes. We\nreview recent developments of theoretical methods in this area of research and\nin particular of density functional (DF) approaches, which provide important\ninsights into microscopic properties of such interfaces. The theories permit to\ndescribe the dependence of adsorption, wettability, solvation forces and\nelectric interfacial phenomena on thermodynamic states and on characteristics\nof tethered chains. Computer simulations for the problems in question are\noverviewed as well. Theoretical results are discussed in relation to simulation\nresults and to some experimental observations."
    },
    {
        "anchor": "Adhesion Induced Instabilities and Pattern Formation in Thin Films of\n  Elastomers and Gels: A hydrostatically stressed soft elastic film circumvents the imposed\nconstraint by undergoing a morphological instability, the wavelength of which\nis dictated by the minimization of the surface and the elastic strain energies\nof the film. While for a single film, the wavelength is entirely dependent on\nits thickness, a co-operative energy minimization dictates that the wavelength\ndepends on both the elastic moduli and thicknesses of two contacting films. The\nwavelength can also depend on the material properties of a film if its surface\ntension has a pronounced effect in comparison to its elasticity. When such a\nconfined film is subjected to a continually increasing normal displacement, the\nmorphological patterns evolve into cracks, which, in turn, govern the adhesive\nfracture behavior of the interface. While, in general, the thickness provides\nthe relevant length scale underlying the well-known Griffith-Kendall criterion\nof debonding of a rigid disc from a confined film, it is modified non-trivially\nby the elasto-capillary number for an ultra-soft film. Depending upon the\ndegree of confinement and the spatial distribution of external stress, various\nanalogs of the canonical instability patterns in liquid systems can also be\nreproduced with thin confined elastic films.",
        "positive": "Experimental observation of triple correlations in fluids: We present arguments for the hypothesis that under some conditions, triple\ncorrelations of density fluctuations in fluids can be detected experimentally\nby the method of molecular spectroscopy. These correlations manifest themselves\nin the form of the so-called 1.5- (i.e., sesquialteral) scattering. The latter\nis of most significance in the pre-asymptotic vicinity of the critical point\nand can be registered along certain thermodynamic paths. Its presence in the\noverall scattering pattern is demonstrated by our processing experimental data\nfor the depolarization factor. Some consequences of these results are\ndiscussed."
    },
    {
        "anchor": "Desalination due to Electrical Image Forces: It will be shown that for a solution of salt dissolved in water in contact\nwith a metallic wall, the concentration of salt ions (both positive and\nnegative) within a few Angstroms of the wall can be large enough to exceed the\nsolubility limit of the salt, as a result of electrical image charge forces. In\naddition, since the dielectric constant of water increases from 2.1 at the wall\nto 81 at about a nanometer from a solid wall, there will be an attractive image\npotential near the plane on which this increase of the dielectric constant\noccurs. The possible existence of these image potentials suggests that the salt\ncan be removed from the water by making salt water flow between an array of\nparallel solid plates..",
        "positive": "Multiscale modeling and simulation of microtubule/motor protein\n  assemblies: Microtubules and motor proteins self organize into biologically important\nassemblies including the mitotic spindle and the centrosomal microtubule array.\nOutside of cells, microtubule-motor mixtures can form novel active\nliquid-crystalline materials driven out of equilibrium by ATP-consuming motor\nproteins. Microscopic motor activity causes polarity-dependent interactions\nbetween motor proteins and microtubules, but how these interactions yield such\nlarger-scale dynamical behavior such as complex flows and defect dynamics is\nnot well understood. We develop a multiscale theory for microtubule-motor\nsystems in which Brownian dynamics simulations of polar microtubules driven by\nmotors are used to study microscopic organization and stresses created by\nmotor-mediated microtubule interactions. We identify polarity-sorting and\ncrosslink tether relaxation as two polar-specific sources of active\ndestabilizing stress. We then develop a continuum Doi-Onsager model that\ncaptures polarity sorting and the hydrodynamic flows generated by these\npolar-specific active stresses. In simulations of active nematic flows on\nimmersed surfaces, the active stresses drive turbulent flow dynamics and\ncontinuous generation and annihilation of disclination defects. The dynamics\nfollow from two instabilities, and accounting for the immersed nature of the\nexperiment yields unambiguous characteristic length and time scales. When\nturning off the hydrodynamics in the Doi-Onsager model, we capture formation of\npolar lanes as observed in the Brownian dynamics simulation."
    },
    {
        "anchor": "Fickian yet non-Gaussian diffusion in two-dimensional Yukawa liquids: We investigate Fickian diffusion in two-dimensional (2D) Yukawa liquids using\nmolecular dynamics simulations. We compute the self-van Hove correlation\nfunction $G_s(r,t)$, and the self-intermediate scattering function $F_s(k,t)$\nand compare these functions with those obtained from mean-squared displacement\nMSD using the Gaussian approximation. According to this approximation, a linear\nMSD with time implies a Gaussian behavior for $G_s(r,t)$ and $F_s(k,t)$ at all\ntimes. Surprisingly, we find that these functions deviate from Gaussian at\nintermediate time scales, indicating the failure of the Gaussian approximation.\nFurthermore, we quantify these deviations by the non-Gaussian parameter, and we\nfind that the deviations increase with decreasing the temperature of the\nliquid. The origin of the non-Gaussian behavior may be the heterogeneous\ndynamics of dust particles observed in 2D Yukawa liquids.",
        "positive": "Giant adsorption of microswimmers: duality of shape asymmetry and wall\n  curvature: The effect of shape asymmetry of microswimmers on their adsorption capacity\nat confining channel walls is studied by a simple dumbbell model. For a shape\npolarity of a forward-swimming cone, like the stroke-averaged shape of a sperm,\nextremely long wall retention times are found, caused by a non-vanishing\ncomponent of the propulsion force pointing steadily into the wall, which grows\nexponentially with the self-propulsion velocity and the shape asymmetry. A\ndirect duality relation between shape asymmetry and wall curvature is proposed\nand verified. Our results are relevant for the design microswimmer with\ncontrolled wall-adhesion properties. In addition, we confirm that pressure in\nactive systems is strongly sensitive to the details of the particle-wall\ninteractions."
    },
    {
        "anchor": "Onset of rebound suppression in non Newtonian droplets post impact on\n  superhydrophobic surfaces: Droplet deposition after impact on superhydrophobic surfaces has been an\nimportant area of study in recent years due to its potential application in\nreduction of pesticides usage. Minute amounts of long chain polymers added to\nwater has been known to arrest the droplet rebound effect on superhydrophobic\nsurfaces. Previous studies have attributed different reasons like extensional\nviscosity, dominance of elastic stresses or slowing down of contact line in\nretraction phase due to stretching of polymer chains. The present study\nattempts to unravel the existence of critical criteria of polymer concentration\nand impact velocity on the inhibition of droplet rebound. The impact velocity\nwill indirectly influence the shear rate during the retraction phase, and the\npolymer concentration dictates the relaxation timescale of the elastic fluids.\nFinally we show that the Weissenberg number (at onset of retraction), which\nquantifies both the elastic effects of polymer chains and the hydrodynamics, is\nthe critical parameter in determining the regime of onset of rebound\nsuppression, and that there exists a critical value which determines the onset\nof bounce arrest. The previous three causes, which are manifestations of\nelastic effects in non-Newtonian fluids, can be related with the proposed\nWeissenberg number criterion.",
        "positive": "Shear Banding from lattice kinetic models with competing interactions: Soft Glassy Materials, Non Linear Rheology, Lattice Kinetic models,\nfrustrated phase separation} We present numerical simulations based on a\nBoltzmann kinetic model with competing interactions, aimed at characterizating\nthe rheological properties of soft-glassy materials. The lattice kinetic model\nis shown to reproduce typical signatures of driven soft-glassy flows in\nconfined geometries, such as Herschel-Bulkley rheology, shear-banding and\nhisteresys. This lends further credit to the present lattice kinetic model as a\nvaluable tool for the theoretical/computational investigation of the rheology\nof driven soft-glassy materials under confinement."
    },
    {
        "anchor": "Controlling cell-matrix traction forces by extracellular geometry: We present a minimal continuum model of strongly adhering cells as active\ncontractile isotropic media and use the model to study the effect of the\ngeometry of the adhesion patch in controlling the spatial distribution of\ntraction and cellular stresses. Activity is introduced as a contractile, hence\nnegative, spatially homogeneous contribution to the pressure. The model shows\nthat patterning of adhesion regions can be used to control traction stress\ndistribution and yields several results consistent with experimental\nobservations. Specifically, the cell spread area is found to increase with\nsubstrate stiffness and an analytic expression for the dependence is obtained\nfor circular cells. The correlation between the magnitude of traction stresses\nand cell boundary curvature is also demonstrated and analyzed.",
        "positive": "Global cross-over dynamics of single semiflexible polymers: We present a mean-field dynamical theory for single semiflexible polymers\nwhich can precisely capture, without fitting parameters, recent fluorescence\ncorrelation spectroscopy results on single monomer kinetics of DNA strands in\nsolution. Our approach works globally, covering three decades of strand length\nand five decades of time: it includes the complex cross-overs occurring between\nstiffness-dominated and flexible bending modes, along with larger-scale\nrotational and center-of-mass motion. The accuracy of the theory stems in part\nfrom long-range hydrodynamic coupling between the monomers, which makes a\nmean-field description more realistic. Its validity extends even to short,\nstiff fragments, where we also test the theory through Brownian hydrodynamics\nsimulations."
    },
    {
        "anchor": "Experimental and Computational Study of the Effect of the System Size on\n  Rough Surfaces Formed by Sedimenting Particles in Quasi-Two-Dimensions: The roughness exponent of surfaces obtained by dispersing silica spheres into\na quasi-two-dimensional cell is examined using experimental and computational\nmethods. The cell consists of two glass plates separated by a gap, which is\ncomparable in size to the diameter of the beads. We have studied the effect of\nchanging the gap between the plates to a limit of about twice the diameter of\nthe beads. If the conventional scaling analysis is performed, the roughness\nexponent is found to be robust against changes in the gap between the plates.\nThe surfaces formed have two roughness exponents in two length scales, which\nhave a crossover length about 1 cm.; however, the computational results do not\nshow the same crossover behavior. The single exponent obtained from the\nsimulations stays between the two roughness exponents obtained in the\nexperiments.",
        "positive": "Gelation impairs small molecule migration in polymer mixtures: Surface segregation of the low-molecular weight component in a polymeric\nmixture leads to degradation of industrial formulations. We report a\nsimultaneous phase separation and surface migration phenomena in\noligomer-polymer and oligomer-gel systems following a temperature quench. We\ncompute equilibrium and time varying migrant density profiles and wetting layer\nthickness using coarse grained molecular dynamics and mesoscale hydrodynamics\nsimulations to demonstrate that surface migration in oligomer-gel systems is\nsignificantly reduced due to network elasticity. Further, phase separation\nprocesses are significantly slowed in gels, modifying the\nLifshitz-Slyozov-Wagner (LSW) law $\\ell(\\tau) \\sim \\tau^{1/3}$. Our work allows\nfor rational design of polymer/gel-oligomer mixtures with predictable surface\nsegregation characteristics."
    },
    {
        "anchor": "Enhanced displacement of phase separating liquid mixtures in 2D confined\n  spaces: Displacing liquid in a confined space is important for technological\nprocesses, ranging from porous membrane separation to CO$_{2}$ sequestration.\nThe liquid to be displaced usually consists of multiple components with\ndifferent solubilities in the displacing liquid. Phase separation and chemical\ncomposition gradients in the liquids can influence the displacement rate. In\nthis work, we investigate the effects of liquid composition on the displacement\nprocess of ternary liquid mixtures in a quasi-2D microchannel where\nliquid-liquid phase separation occurs concurrently. We focused on model ternary\nmixtures containing 1-octanol, ethanol, and water. These mixtures are displaced\nwith water or with ethanol aqueous solution. The spatial distribution of\nsubphases arising from phase separation and the displacement rates of the\nsolution are impacted by the initial ternary solution composition. The boundary\nbetween the solution and displacing liquid changes from a defined interface to\na diffusive interface as the initial 1-octanol composition in the solution is\nreduced. The displacement rate also varies non-linearly with the initial\n1-octanol composition. The slowest displacement rate arises in the intermediate\n1-octanol concentration, where a stable three-zone configuration forms at the\nboundary. At very low 1-octanol concentration, the displacement rate is fast,\nassociated with droplet formation and motion driven by the chemical\nconcentration gradients formed during phase separation. The excessive energy\nprovided from phase separation may contribute to the enhanced displacement at\nintermediate to high 1-octanol concentrations, but not at the low 1-octanol\nconcentration with enhancement from induced flow in confinement. The knowledge\ngained from this study highlights the importance of manipulating phase\nseparation to enhance mass transport in confinement for a wide range of\nseparation processes.",
        "positive": "Adsorption of metallic ions from aqueous solution on surfactant\n  aggregates: a molecular dynamics study: Metallic ion adsorption on surfactant aggregates were studied with Molecular\ndynamics simulations. Using ionic salts, such as lead sulfate (PbSO$_4$) and\naluminum sulfate [Al$_2$(SO$_4$)$_3$], adsorption of lead and aluminum were\ninvestigated at different salt concentrations and different surfactant\naggregates (micelles) sizes. The micelles were constructed with spherical\nshapes composed of sodium dodecyl sulfate (SDS) anionic surfactants. The\nelectrostatic interactions between the positive ions and the negative SDS\nheadgroups promote capture of the metal particles on the aggregate surface.\nMetal adsorption was analyzed in terms of radial density profiles, partial pair\ndistribution functions and adsorption isotherms. It is showed that SDS micelles\nadsorb better lead than aluminum ions regardless of the size of the aggregates\nand salt concentrations."
    },
    {
        "anchor": "Multi-scale coarse-graining of diblock copolymer self-assembly: from\n  monomers to ordered micelles: Starting from a microscopic lattice model, we investigate clustering,\nmicellization and micelle ordering in semi-dilute solutions of AB diblock\ncopolymers in a selective solvent. To bridge the gap in length scales, from\nmonomers to ordered micellar structures, we implement a two-step coarse\ngraining strategy, whereby the AB copolymers are mapped onto ``ultrasoft''\ndumbells with monomer-averaged effective interactions between the centres of\nmass of the blocks. Monte Carlo simulations of this coarse-grained model yield\nclear-cut evidence for self-assembly into micelles with a mean aggregation\nnumber n of roughly 100 beyond a critical concentration. At a slightly higher\nconcentration the micelles spontaneously undergo a disorder-order transition to\na cubic phase. We determine the effective potential between these micelles from\nfirst principles.",
        "positive": "Ion-specific colloidal aggregation: population balance equations and\n  potential of mean force: Recently reported colloidal aggregation data obtained for different\nmonovalent salts (NaCl, NaNO$_3$, and NaSCN) and at high electrolyte\nconcentrations are matched with the stochastic solutions of the master equation\nto obtain bond average lifetimes and bond formation probabilities. This was\ndone for a cationic and an anionic system of similar particle size and absolute\ncharge. Following the series Cl$^-$, NO$_3^-$, SCN$^-$, the parameters obtained\nfrom the fitting procedure to the kinetic data suggest: i) The existence of a\npotential of mean force (PMF) barrier and an increasing trend for it for both\nlatices. ii) An increasing trend for the PMF at contact, for the cationic\nsystem, and a practically constant value for the anionic system. iii) A\ndecreasing trend for the depth of the secondary minimum. This complex behavior\nis in general supported by Monte Carlo simulations, which are implemented to\nobtain the PMF of a pair of colloidal particles immersed in the corresponding\nelectrolyte solution. All these findings contrast the Derjaguin, Landau,\nVerwey, and Overbeek theory predictions."
    },
    {
        "anchor": "Turing's diffusive threshold in random reaction-diffusion systems: Turing instabilities of reaction-diffusion systems can only arise if the\ndiffusivities of the chemical species are sufficiently different. This\nthreshold is unphysical in most systems with $N=2$ diffusing species, forcing\nexperimental realizations of the instability to rely on fluctuations or\nadditional nondiffusing species. Here we ask whether this diffusive threshold\nlowers for $N>2$ to allow \"true\" Turing instabilities. Inspired by May's\nanalysis of the stability of random ecological communities, we analyze the\nprobability distribution of the diffusive threshold in reaction-diffusion\nsystems defined by random matrices describing linearized dynamics near a\nhomogeneous fixed point. In the numerically tractable cases $N\\leqslant 6$, we\nfind that the diffusive threshold becomes more likely to be smaller and\nphysical as $N$ increases and that most of these many-species instabilities\ncannot be described by reduced models with fewer species.",
        "positive": "Integral equation study of effective attraction between like-charged\n  particles mediated by cations: Comparison between IPY2 and HNC closures: Effective interactions between like-charged particles immersed in an\nelectrolyte solution were calculated using two integral equation theories,\nhypernetted-chain (HNC)-Ornstein--Zernike (OZ) and ionic Percus--Yevick 2\n(IPY2)-OZ. When the HNC-OZ theory was adopted, the electrolyte concentration\ndependence of the effective interaction showed a reentrant behavior. By\ncontrast, the IPY2-OZ theory did not indicate the behavior. Monte Carlo\nsimulations were performed for one of the model systems, and the results agreed\nqualitatively with those calculated using the HNC-OZ theory."
    },
    {
        "anchor": "From Hindered to Promoted Settling in Dispersions of Attractive\n  Colloids: Simulation, Modeling, and Application to Macromolecular\n  Characterization: The settling of colloidal particles with short-ranged attractions is\ninvestigated via highly resolved immersed boundary simulations. At modest\nvolume fractions, we show that inter-colloid attractions lead to clustering\nthat reduces the hinderance to settling imposed by fluid back flow. For\nsufficient attraction strength, increasing the particle concentration grows the\nparticle clusters, which further increases the mean settling rate in a physical\nmode termed promoted settling. The immersed boundary simulations are compared\nto recent experimental measurements of the settling rate in nanoparticle\ndispersions for which particles are driven to aggregate by short-ranged\ndepletion attractions. The simulations are able to quantitatively reproduce the\nexperimental results. We show that a simple, empirical model for the settling\nrate of adhesive hard sphere dispersions can be derived from a combination of\nthe experimental and computational data as well as analytical results valid in\ncertain asymptotic limits of the concentration and attraction strength. This\nmodel naturally extends the Richardson-Zaki formalism used to describe hindered\nsettling of hard, repulsive spheres. Experimental measurements of the\ncollective diffusion coefficient in concentrated solutions of globular proteins\nare used to illustrate inference of effective interaction parameters for\nsticky, globular macromolecules using this new empirical model. Finally,\napplication of the simulation methods and empirical model to other colloidal\nsystems are discussed.",
        "positive": "Molecular dynamics simulations of oscillatory Couette flows with slip\n  boundary conditions: The effect of interfacial slip on steady-state and time-periodic flows of\nmonatomic liquids is investigated using non-equilibrium molecular dynamics\nsimulations. The fluid phase is confined between atomically smooth rigid walls,\nand the fluid flows are induced by moving one of the walls. In steady shear\nflows, the slip length increases almost linearly with shear rate. We found that\nthe velocity profiles in oscillatory flows are well described by the Stokes\nflow solution with the slip length that depends on the local shear rate.\nInterestingly, the rate dependence of the slip length obtained in steady shear\nflows is recovered when the slip length in oscillatory flows is plotted as a\nfunction of the local shear rate magnitude. For both types of flows, the\nfriction coefficient at the liquid-solid interface correlates well with the\nstructure of the first fluid layer near the solid wall."
    },
    {
        "anchor": "Complex Phase Behavior of Repulsive Step Potential Systems in Three\n  Dimensions: The comprehensive computer simulation study of the phase diagram of the\nrepulsive step potential system in three dimensions is represented. We show\nthat the system with a simple purely repulsive isotropic potential demonstrates\na number of unusual features. The maxima and minima on the melting curve are\nfound for some regions of potential parameters. It is shown that the phase\ndiagram in $\\rho-T$ plane includes two isostructural crystalline parts\nseparated by the disordered phase which is amorphous at low enough\ntemperatures. Phase diagram in the (P-T) plane shows that the transition to the\namorphous state occurs approximately along the extrapolated spinodals.\nStructural FCC-BCC phase transition is found at high densities.",
        "positive": "Induced correlations and rupture of molecular chaos by anisotropic\n  dissipative Janus hard disks: A system of smooth \"frozen\" Janus-type disks is studied. Such disks cannot\nrotate and are divided by their diameter into two sides of different\ninelasticities. Taking as a reference a system of colored elastic disks, we\nfind differences in the behavior of the collisions once the anisotropy is\nincluded. A homogeneous state, akin to the homogeneous cooling state of\ngranular gases, is seen to arise and the singular behavior of both the\ncollisions and the precollisional correlations are highlighted."
    },
    {
        "anchor": "Shear induced tuning and memory effects in colloidal gels of rods and\n  spheres: Shear history plays an important role in determining the linear and nonlinear\nrheological response of colloidal gels and can be used for tuning their\nstructure and flow properties. Increasing colloidal particle aspect ratio\nlowers the critical volume fraction for gelation due to an increase of the\nparticle excluded volume. Using a combination of rheology and confocal\nmicroscopy we investigate the effect of steady and oscillatory pre-shear\nhistory on the structure and rheology of colloidal gels formed by silica\nspheres and rods of length L and diameter D (L/D = 10) dispersed in 11 M CsCl\nsolution. We use a non-dimensional Mason number, Mn (= F_visc./F_attr.) to\ncompare the effect of steady and oscillatory pre-shear on gel viscoelasticity.\nWe show that after pre-shearing at intermediate Mn, attractive sphere gel\nexhibits strengthening whereas attractive rod gel exhibits weakening.\nRheo-imaging of gels of attractive rods shows that at intermediate Mn,\noscillatory pre-shear induces large compact rod clusters in the gel\nmicrostructure, compared to steady pre-shear. Our study highlights the impact\nof particle shape on gel structuring under flow and viscoelasticity after shear\ncessation.",
        "positive": "Phase coexistence in the hard-sphere Yukawa chain fluid with chain\n  length polydispersity: High temperature approximation: High temperature approximation (HTA) is used to describe the phase behavior\nof polydisperse multi-Yukawa hard-sphere chain fluid mixtures with chain length\npolydispersity. It is demonstrated that in the frames of the HTA the model\nbelongs to the class of ``truncatable free energy models'', i.e. the models\nwith thermodynamical properties (Helmholtz free energy, chemical potential and\npressure) defined by the finite number of generalized moments. Using this\nproperty we were able to calculate the complete phase diagram (i.e., cloud and\nshadow curves as well as binodals) and chain length distribution functions of\nthe coexisting phases."
    },
    {
        "anchor": "Computer simulations of an impurity in a granular gas under planar\n  Couette flow: We present in this work results from numerical solutions, obtained by means\nof the direct simulation Monte Carlo (DSMC) method, of the Boltzmann and\nBoltzmann--Lorentz equations for an impurity immersed in a granular gas under\nplanar Couette flow. The DSMC results are compared with the exact solution of a\nrecent kinetic model for the same problem. The results confirm that, in steady\nstates and over a wide range of parameter values, the state of the impurity is\nenslaved to that of the host gas: it follows the same flow velocity profile,\nits concentration (relative to that of the granular gas) is constant in the\nbulk region, and the impurity/gas temperature ratio is also constant. We\ndetermine also the rheological properties and nonlinear hydrodynamic transport\ncoefficients for the impurity, finding a good semi-quantitative agreement\nbetween the DSMC results and the theoretical predictions.",
        "positive": "Electroosmotic flow dipole: experimental observation and flow field\n  patterning: We experimentally demonstrate the phenomenon of electroosmotic dipole flow\nthat occurs around a localized surface charge region under the application of\nan external electric field in a Hele-Shaw cell. We use localized deposition of\npolyelectrolytes to create well-controlled surface charge variations, and show\nthat for a disk-shaped spot, the internal pressure distribution that arises,\nresults in uniform flow within the spot and dipole flow around it. We further\ndemonstrate the superposition of surface charge spots to create complex flow\npatterns, without the use of physical walls."
    },
    {
        "anchor": "Viscoelastic coarsening of quasi-2D foam: Foams are unstable jammed materials. They evolve over timescales comparable\nto their \"time of use\", which makes the study of their destabilisation\nmechanisms crucial for applications. In practice, many foams are made from\nviscoelastic fluids, which are observed to prolong their lifetimes. Despite\ntheir importance we lack understanding of the coarsening mechanism in such\nsystems. We probe the effect of continuous phase viscoelasticity on foam\ncoarsening with foamed emulsions. We show that bubble size evolution is\nstrongly slowed down and foam structure hugely impacted. The main mechanisms\nresponsible are the absence of continuous phase redistribution and a\nnon-trivial link between foam structure and mechanical properties. These\ncombine to give spatially heterogeneous coarsening. Beyond their importance in\nthe design of foamy materials, the results give a macroscopic vision of phase\nseparation in a viscoelastic medium.",
        "positive": "Ion-ion correlation and charge reversal at titrating solid interfaces: Confronting grand canonical titration Monte Carlo simulations (MC) with\nrecently published titration and charge reversal (CR) experiments on silica\nsurfaces by Dove et al. and van der Heyden it et al, we show that ion-ion\ncorrelations quantitatively explain why divalent counterions strongly promote\nsurface charge which, in turn, eventually causes a charge reversal (CR).\nTitration and CR results from simulations and experiments are in excellent\nagreement without any fitting parameters. This is the first unambiguous\nevidence that ion-ion correlations are instrumental in the creation of highly\ncharged surfaces and responsible for their CR. Finally, we show that charge\ncorrelations result in \"anomalous\" charge regulation in strongly coupled\nconditions in qualitative desagreement with its classical treatment."
    },
    {
        "anchor": "Mechanical activation of reversible bonds by low amplitude high\n  frequencies excitations: Reversible covalent or supramolecular bonds play an important role in\nmaterials science and in biological systems. The equilibrium between open and\nclosed bonds and the association rate can be controlled thermally, chemically,\nby mechanical pulling, ultrasound or catalysts. In practice, these intrinsic\nequilibrium methods either suffer from a limited range of tunability or may\ndamage the system. Here, we present a non-equilibrium strategy that exploits\nthe dissipative properties of the system to control and change the dynamic\nproperties of sacrificial and reversible networks. We show theoretically and\nnumerically how high-frequency mechanical oscillations of very low amplitude\ncan open or close bonds. This mechanism indicates how reversible bonds could\nalleviate mechanical fatigue of materials especially at low temperatures where\nthey are fragile. In another area, it suggests that the system can be actively\nmodified by the application of ultrasound to induce gel-fluid transitions and\nto activate or deactivate adhesion properties.",
        "positive": "Membrane-Mediated Interactions Between Nonspherical Elastic Particles: The transport of particles across lipid-bilayer membranes is important for\nbiological cells to exchange information and material with their environment.\nLarge particles often get wrapped by membranes, a process which has been\nintensively investigated in the case of hard particles. However, many particles\nin vivo and in vitro are deformable, e.g., vesicles, filamentous viruses,\nmacromolecular condensates, polymer-grafted nanoparticles, and microgels.\nVesicles may serve as a generic model system for deformable particles. Here, we\nstudy non-spherical vesicles with various sizes, shapes, and elastic properties\nat initially planar lipid-bilayer membranes. Using the Helfrich Hamiltonian,\ntriangulated membranes, and energy minimization, we predict the interplay of\nvesicle shapes and wrapping states. Increasing particle softness enhances the\nstability of shallow-wrapped and deep-wrapped states over non-wrapped and\ncomplete-wrapped states. The free membrane mediates an interaction between\npartial-wrapped vesicles. For the pair interaction between deep-wrapped\nvesicles, we predict repulsion. For shallow-wrapped vesicles, we predict\nattraction for tip-to-tip orientation and repulsion for side-by-side\norientation. Our predictions may guide the design and fabrication of deformable\nparticles for efficient use in medical applications, such as targeted drug\ndelivery."
    },
    {
        "anchor": "Collective Ratchet Effects and Reversals for Active Matter Particles on\n  Quasi-One-Dimensional Asymmetric Substrates: Using computer simulations, we study a two-dimensional system of sterically\ninteracting self-mobile run-and-tumble disk-shaped particles with an underlying\nperiodic quasi-one-dimensional asymmetric substrate, and show that a rich\nvariety of collective active ratchet behaviors arise as a function of particle\ndensity, activity, substrate strength, and substrate period. The ratchet\nefficiency is nonmonotonic since the ratcheting is enhanced by increased\nactivity but diminished by the onset of self-clustering of the active\nparticles. Increasing the particle density decreases the ratchet efficiency for\nweak substrates but increases the ratchet efficiency for strong substrates due\nto collective hopping events. At the highest particle densities, the ratchet\nmotion is destroyed by a self-jamming effect. We show that it is possible to\nrealize reversals of the ratchet effect, where the net flux of particles is\nalong the hard rather than the easy direction of the substrate asymmetry. The\nreversals occur in the strong substrate limit when multiple rows of active\nparticles can be confined in each substrate minimum, permitting emergent\nparticle-like excitations to appear that experience an inverted effective\nsubstrate potential. We map out a phase diagram of the forward and reverse\nratchet effects as a function of the particle density, activity, and substrate\nproperties.",
        "positive": "Field Theory Analysis of Laplacian Growth Models: We consider Laplacian growth problems using a field theory approach. In\nparticular we consider the Saffman-Taylor (ST) problem. The idealized settings\nof the problem, with vanishing surface tension between the bubble and the\nsurrounding fluid, is singular due to the formation of cusps after a finite\ntime (for generic initial conditions). A natural regularization of the cusp, is\nthe addition of surface tension, but this complicates the mathematical\ndescription of the problem a great deal. We discuss a different method of\nregularization which arises from the relation of the ST problem with integrable\nsystems and matrix models."
    },
    {
        "anchor": "Hexatic Order and Surface Ripples in Spherical Geometries: In flat geometries, two dimensional hexatic order has only a minor effect on\ncapillary waves on a liquid substrate and on undulation modes in lipid\nbilayers. However, extended bond orientational order alters the long wavelength\nspectrum of these ripples in spherical geometries. We calculate this frequency\nshift and suggest that it might be detectable in lipid bilayer vesicles, at the\nsurface of liquid metals and in multielectron bubbles in liquid helium at low\ntemperatures. Hexatic order also leads to a shift in the threshold for the\nfission instability induced in the later two systems by an excess of electric\ncharge.",
        "positive": "Diffusion in systems crowded by active force-dipole molecules: Experimental studies of systems containing active proteins that undergo\nconformational changes driven by catalytic chemical reactions have shown that\nthe diffusion coefficients of passive tracer particles and active molecules are\nlarger than the corresponding values when chemical activity is absent. Various\nmechanisms have been proposed for such behavior, including, among others, force\ndipole interactions of molecular motors moving on filaments and collective\nhydrodynamic effects arising from active proteins. Simulations of a\nmulti-component system containing active dumbbell molecules that cycle between\nopen and closed states, a passive tracer particle and solvent molecules are\ncarried out. Consistent with experiments, it is shown that the diffusion\ncoefficients of both passive particles and the dumbbells themselves are\nenhanced when the dumbbells are active. The dependence of the diffusion\nenhancement on the volume fraction of dumbbells is determined, and the effects\nof crowding by active dumbbell molecules are shown to differ from those due to\ninactive molecules."
    },
    {
        "anchor": "Influence of Preservation Temperature on the Measured Mechanical\n  Properties of Brain Tissue: The large variability in experimentally measured mechanical properties of\nbrain tissue is due to many factors including heterogeneity, anisotropy, age\ndependence and post-mortem time. Moreover, differences in test protocols also\ninfluence these measured properties. This paper shows that the temperature at\nwhich porcine brain tissue is stored or preserved prior to testing has a\nsignificant effect on the mechanical properties of brain tissue, even when\ntests are conducted at the same temperatures. Three groups of brain tissue were\nstored separately for at least one hour at three different preservation\ntemperatures, i.e., ice cold, room temperature (22C) and body temperature\n(37C), prior to them all being tested at room temperature (approx. 22C).\nSignificant differences in the corresponding initial elastic shear modulus mu\n(Pa) (at various amounts of shear, K, i.e., 0-0.2) were observed. The initial\nelastic moduli were 1043 +/- 271 Pa, 714 +/- 210 Pa and 497 +/- 156 Pa (mean\n+/- SD) at preservation temperatures of ice cold, 22C and 37C, respectively.\nBased on this investigation, it is strongly recommended that brain tissue\nsamples must be preserved at an ice-cold temperature prior to testing in order\nto minimize the difference between the measured in vitro test results and the\nin vivo properties. A by-product of the study is that simple shear tests allow\nfor large, almost perfectly homogeneous deformation of brain matter.",
        "positive": "Elasticity of granular packings close to Jamming. Elasticit\u00e9 des\n  empilements granulaires proche de la transition de blocage: We investigate experimentally the mechanical response to shear of a 2D\npacking of grains across the jamming transition. First, we develop a dedicated\nexperimental setup, together with tracking and photoelastic techniques in order\nto prepare the packing in a controlled fashion and to quantify the stress and\nstrain tensors at the grain scale. Second, we install a inflating probe (a 2D\n\"balloon\"), which shears the packing with a cylindrical symmetry. We probe\nexperimentally stresses and strains for strain amplitudes as low as $10^{-3}$\nand for a range of packing fractions within $2\\%$ variation around the jamming\ntransition. We observe not only that shear strain induces shear stresses, but\nalso normal stresses. Moreover, we show that both shear and normal stresses\nbehave nonlinearly with the shear strain. Finally, we show by scaling analysis\nthat the constitutive laws are controlled by the Jamming transition."
    },
    {
        "anchor": "Perturbing the catenoid: stability and mechanical properties of\n  non-axisymmetric minimal surfaces: Minimal surface problems arise naturally in many soft matter systems whose\nfree energies are dominated by surface or interface energies. Of particular\ninterest are the shapes, stability and mechanical stresses of minimal surfaces\nspanning specific geometric boundaries. The \"catenoid\" is the best-known\nexample where an analytical solution is known which describes the form and\nstability of a minimal surface held between two parallel, concentric circular\nframes. Here we extend this problem to non-axisymmetric, parallel frame shapes\nof different orientations, by developing a perturbation approach around the\nknown catenoid solution. We show that the predictions of the perturbation\ntheory are in good agreement with experiments on soap films and finite element\nsimulations (Surface Evolver). Combining theory, experiment and simulation, we\nanalyse in depth how the shapes, stability and mechanical properties of the\nminimal surfaces depend on the type and orientation of elliptical and\nthree-leaf clover shaped frames. In the limit of perfectly aligned\nnon-axisymmetric frames, our predictions show excellent agreement with a recent\ntheory established by Alimov et al (M. M. Alimov, A. V. Bazilevsky and K. G.\nKornev, Physics of Fluids, 2021, 33, 052104). Moreover, we put in evidence the\nintriguing capacity of minimal surfaces between non-axisymmetric frames to\ntransmit a mechanical torque despite being completely liquid. These forces\ncould be interesting to exploit for mechanical self-assembly of soft matter\nsystems or as highly sensitive force captors.",
        "positive": "Propagating Waves in a Monolayer of Gas-Fluidized Rods: We report on an observation of propagating compression waves in a\nquasi-two-dimensional monolayer of apolar granular rods fluidized by an upflow\nof air. The collective wave speed is an order of magnitude faster than the\nspeed of the particles. This gives rise to anomalously large number\nfluctuations dN ~ $N^{0.72 \\pm 0.04}$, which are greater than ordinary number\nfluctuations of N^{1/2}. We characterize the waves by calculating the\nspatiotemporal power spectrum of the density. The position of observed peaks,\nas a function of frequency w and wavevector k, yields a linear dispersion\nrelationship in the long-time, long-wavelength limit and a wavespeed c = w/k.\nRepeating this analysis for systems at different densities and air speeds, we\nobserve a linear increase in the wavespeed with increasing packing fraction\nwith no dependence on the airflow. Although air-fluidized rods self-propel\nindividually or in dilute collections, the parallel and perpendicular\nroot-mean-square speeds of the rods indicate that they no longer self-propel\nwhen propagating waves are present. Based on this mutual exclusivity, we map\nout the phase behavior for the existence of waves vs self-propulsion as a\nfunction of density and fluidizing airflow."
    },
    {
        "anchor": "All Optical Formation of an Atomic Bose-Einstein Condensate: We have created a Bose-Einstein condensate of 87Rb atoms directly in an\noptical trap. We employ a quasi-electrostatic dipole force trap formed by two\ncrossed CO_2 laser beams. Loading directly from a sub-doppler laser-cooled\ncloud of atoms results in initial phase space densities of ~1/200.\nEvaporatively cooling through the BEC transition is achieved by lowering the\npower in the trapping beams over ~ 2 s. The resulting condensates are F=1\nspinors with 3.5 x 10^4 atoms distributed between the m_F = (-1,0,1) states.",
        "positive": "Patterning active materials with addressable soft interfaces: Motor-proteins are responsible for transport inside cells. Harnessing their\nactivity is key towards developing new nano-technologies, or functional\nbiomaterials. Cytoskeleton-like networks, recently tailored in vitro, result\nfrom the self-assembly of subcellular autonomous units. Taming this biological\nactivity bottom-up may thus require molecular level alterations compromising\nprotein integrity. Taking a top-down perspective, here we prove that the\nseemingly chaotic flows of a tubulin-kinesin active gel can be forced to adopt\nwell-defined spatial directions by tuning the anisotropic viscosity of a\ncontacting lamellar oil. Different configurations of the active material are\nrealized, when the passive oil is either unforced or commanded by a magnetic\nfield. The inherent instability of the extensile active fluid is thus spatially\nregularized, leading to organized flow patterns, endowed with characteristic\nlength and time scales. Our finding paves the way for designing hybrid\nactive/passive systems where ATP-driven dynamics can be externally conditioned."
    },
    {
        "anchor": "Water-like Anomalies of Core-Softened Fluids: Dependence on the\n  Trajectories in ($P\u03c1T$) Space: In the present article we carry out a molecular dynamics study of the\ncore-softened system and show that the existence of the water-like anomalies in\nthis system depends on the trajectory in $P-\\rho-T$ space along which the\nbehavior of the system is studied. For example, diffusion and structural\nanomalies are visible along isotherms, but disappears along the isochores and\nisobars, while density anomaly exists along isochors. We analyze the\napplicability of the Rosenfeld entropy scaling relations to this system in the\nregions with the water-like anomalies. It is shown that the validity of the of\nRosenfeld scaling relation for the diffusion coefficient also depends on the\ntrajectory in the $P-\\rho-T$ space along which the kinetic coefficients and the\nexcess entropy are calculated.",
        "positive": "Chemically Active Wetting: Wetting of liquid droplets on passive surfaces is ubiquitous in our daily\nlives, and the governing physical laws are well-understood. When surfaces\nbecome active, however, the governing laws of wetting remain elusive. Here we\npropose chemically active wetting as a new class of active systems where the\nsurface is active due to a binding process that is maintained away from\nequilibrium. We derive the corresponding non-equilibrium thermodynamic theory\nand show that active binding fundamentally changes the wetting behavior,\nleading to steady, non-equilibrium states with droplet shapes reminiscent of a\npancake or a mushroom. The origin of such anomalous shapes can be explained by\nmapping to electrostatics, where pairs of binding sinks and sources correspond\nto electrostatic dipoles along the triple line. This is an example of a more\ngeneral analogy, where localized chemical activity gives rise to a multipole\nfield of the chemical potential. The underlying physics is relevant for cells,\nwhere droplet-forming proteins can bind to membranes accompanied by the\nturnover of biological fuels."
    },
    {
        "anchor": "Ground and excited states of spinor Fermi gases in tight waveguides and\n  the Lieb-Liniger-Heisenberg model: The ground and excited states of a one-dimensional (1D) spin-1/2 Fermi gas\n(SFG) with both attractive zero-range odd-wave interactions and repulsive\nzero-range even-wave interactions are mapped exactly to a 1D\nLieb-Liniger-Heisenberg (LLH) model with delta-function repulsions depending on\nisotropic Heisenberg spin-spin interactions, such that the complete SFG and LLH\nenergy spectra are identical. The ground state in the ferromagnetic phase is\ngiven exactly by the Lieb-Liniger (LL) Bethe ansatz, and that in the\nantiferromagnetic phase by a variational method combining Bethe ansatz\nsolutions of the LL and 1D Heisenberg models. There are excitation branches\ncorresponding to LL type I and II phonons and spin waves, the latter behaving\nquadratically for small wave number in the ferromagnetic phase and linearly in\nthe antiferromagnetic phase.",
        "positive": "Dynamic swarms regulate the morphology and distribution of soft membrane\n  domains: We study the dynamic structure of lipid domain inclusions embedded within a\nphase-separated reconstituted lipid bilayer in contact with a swarming flow of\ngliding filamentous actin. Passive circular domains transition into\nhighly-deformed morphologies that continuously elongate, rotate, and pinch off\ninto smaller fragments, leading to a dynamic steady state with approximately\n23x speed up in the relaxation of the intermediate scattering function compared\nto passive membrane domains driven by purely thermal forces. To corroborate\nexperimental results, we develop a phase-field model of the lipid domains with\ntwo-way coupling to the Toner-Tu equations. We report phase domains that become\nentrained in the chaotic eddy patterns, with oscillating waves of domains that\ncorrelate with the dominant wavelengths of the Toner-Tu flow fields."
    },
    {
        "anchor": "Competitive Heterogeneous Nucleation onto a Microscopic Impurity in a\n  Potts Model: Many metastable systems can nucleate to multiple competing stable or\nintermediate metastable states. In this work, a Potts model, subject to\nexternal fields, is used to study the competitive nucleation of two phases\nattempting to grow on a microscopic impurity. Monte Carlo simulations are used\nto calculate the free energy surfaces for the system under different\nconditions, where the relative stability of the phases is adjusted by changing\nthe interaction parameters, and the nucleation rates obtained using\nmulticomponent transition state theory are compared with the rates measured\nusing the survival probability method. We find that the two methods predict\nsimilar nucleation rates when the free energy barrier used in the transition\nstate theory is defined as the work required to form a critical embryo from the\nmetastable phase. An analysis of the free energy surfaces also reveals that the\ncompetition between the nucleating phases leads to an effective drying of the\nimpurity which slows down the nucleation rate compared to the single phase\ncase.",
        "positive": "MATILDA.FT, a Mesoscale Simulation Package for Inhomogeneous Soft Matter: In this paper we announce the public release of a massively-parallel,\nGPU-accelerated software, which is the first to combine both coarse-grained\nmolecular dynamics and field-theoretical simulations in one simulation package.\nMATILDA.FT (Mesoscale, Accelerated, Theoretically-Informed, Langevin,\nDissipative particle dynamics, and Field Theory) was designed from the\nground-up to run on CUDA-enabled GPUs, with the Thrust library acceleration,\nenabling it to harness the possibility of massive parallelism to efficiently\nsimulate systems on a mesoscopic scale. MATILDA.FT is a versatile software,\nenabling the users to use either Langevin dynamics or Field Theory to model\ntheir systems - all within the same software. It has been used to model a\nvariety of systems, from polymer solutions, and nanoparticle-polymer\ninterfaces, to coarse-grained peptide models, and liquid crystals. MATILDA.FT\nis written in CUDA/C++ and is object oriented, making its source-code easy to\nunderstand and extend. The software comes with dedicated post-processing and\nanalysis tools, as well as the detailed documentation and relevant examples.\nBelow, we present an overview of currently available features. We explain in\ndetail the logic of parallel algorithms and methods. We provide necessary\ntheoretical background, and present examples of recent research projects which\nutilized MATILDA.FT as the simulation engine. We also demonstrate how the code\ncan be easily extended, and present the plan for the future development. The\nsource code, along with the documentation, additional tools and examples can be\nfound on GitHub repository."
    },
    {
        "anchor": "A polymer brush theory for quantitative prediction of maximum height\n  change between dry and wet states: Polymer brushes can grow on almost any solid surface, and by design, exhibit\ndiverse properties and functionalities, thus they have been widely used in many\nemerging applications in engineering, energy, and medicine. In particular, some\napplications such as actuation, molecule release, and friction switch require\nthe polymer brushes to change their heights between dry and wet states, and\nmaximizing such height change is critical for the optimal performance of these\napplications. While scaling laws have long been proposed to qualitatively\ndetermine brush heights, a theory that can quantitatively predict brush heights\nand conditions for maximizing brush height change is still lacking yet is\nvaluable for the practical design of polymer brushes. Here, we take a\nthermodynamic approach to formulate a polymer brush theory to calculate brush\nheights at various conditions of graft area, degree of polymerization (DP), and\nsolvent qualities. Our model consists of two parts-the freely-jointed chain\nmodel to describe the elasticity of brushes and the Flory-Rehner model to\ndescribe the mixing of brushes and solvents. The calculated brush heights at\nboth dry and wet states fairly agree with the experimental data from the\nliterature. The calculated brush heights are further used to determine the\nconditions for the maximum brush height change. Our theory can guide the design\nof polymer brushes for optimal functional performance in various applications\nand also can couple with other models to describe more complex behaviors of\npolymer brushes.",
        "positive": "Two-step percolation in aggregating systems: The two-step percolation behavior in aggregating systems was studied both\nexperimentally and by means of Monte Carlo (MC) simulations. In experimental\nstudies, the electrical conductivity, $\\sigma$, of colloidal suspension of\nmultiwalled carbon nanotubes (CNTs) in decane was measured. The suspension was\nsubmitted to mechanical de-liquoring in a planar filtration-compression\nconductometric cell. During de-liquoring, the distance between the measuring\nelectrodes continuously decreased and the CNT volume fraction $\\varphi$\ncontinuously increased (from $10^{-3}$ up to $\\approx 0.3$% v/v). The two\npercolation thresholds at $\\varphi_{1}\\lesssim 10^{-3}$ and $\\varphi_{2}\\approx\n10^{-2}$ can reflect the interpenetration of loose CNT aggregates and\npercolation across the compact conducting aggregates, respectively. The MC\ncomputational model accounted for the core-shell structure of conducting\nparticles or their aggregates, the tendency of a particle for aggregation, the\nformation of solvation shells, and the elongated geometry of the conductometric\ncell. The MC studies revealed two smoothed percolation transitions in\n$\\sigma(\\varphi)$ dependencies that correspond to the percolation through the\nshells and cores, respectively. The data demonstrated a noticeable impact of\nparticle aggregation on anisotropy in electrical conductivity $\\sigma(\\varphi)$\nmeasured along different directions in the conductometric cell."
    },
    {
        "anchor": "Flow around topological defects in active nematic films: We study the active flow around isolated defects and the self-propulsion\nvelocity of $+1/2$ defects in an active nematic film with both viscous\ndissipation (with viscosity $\\eta$) and frictional damping $\\Gamma$ with a\nsubstrate. The interplay between these two dissipation mechanisms is controlled\nby the hydrodynamic dissipation length $\\ell_d=\\sqrt{\\eta/\\Gamma}$ that screens\nthe flows. For an isolated defect, in the absence of screening from other\ndefects, the size of the vortical flows around the defect is controlled by the\nsystem size $R$. In the presence of friction that leads to a finite value of\n$\\ell_d$, the vorticity field decays to zero on the lengthscales larger than\n$\\ell_d$. We show that the self-propulsion velocity of $+1/2$ defects grows\nwith $R$ in small systems where $R<\\ell_d$, while in the infinite system limit\nor when $R\\gg \\ell_d$, it approaches a constant value determined by $\\ell_d$.",
        "positive": "Solvent mediated interactions between model colloids and interfaces: A\n  microscopic approach: We determine the solvent mediated contribution to the effective potentials\nfor model colloidal or nano- particles dispersed in a binary solvent that\nexhibits fluid-fluid phase separation. Using a simple density functional theory\nwe calculate the density profiles of both solvent species in the presence of\nthe `colloids', which are treated as external potentials, and determine the\nsolvent mediated (SM) potentials. Specifically, we calculate SM potentials\nbetween (i) two colloids, (ii) a colloid and a planar fluid-fluid interface,\nand (iii) a colloid and a planar wall with an adsorbed wetting film. We\nconsider three different types of colloidal particles: colloid A which prefers\nthe bulk solvent phase rich in species 2, colloid C which prefers the solvent\nphase rich in species 1, and `neutral' colloid B which has no strong preference\nfor either phase, i.e. the free energies to insert the colloid into either of\nthe coexisting bulk phases are almost equal. When a colloid which has a\npreference for one of the two solvent phases is inserted into the disfavored\nphase at statepoints close to coexistence a thick adsorbed `wetting' film of\nthe preferred phase may form around the colloids. The presence of the adsorbed\nfilm has a profound influence on the form of the SM potentials."
    },
    {
        "anchor": "Nonlinear competition between asters and stripes in\n  filament-motor-systems: A model for polar filaments interacting via molecular motor complexes is\ninvestigated which exhibits bifurcations to spatial patterns. It is shown that\nthe homogeneous distribution of filaments, such as actin or microtubules, may\nbecome either unstable with respect to an orientational instability of a finite\nwave number or with respect to modulations of the filament density, where long\nwavelength modes are amplified as well. Above threshold nonlinear interactions\nselect either stripe patterns or periodic asters. The existence and stability\nranges of each pattern close to threshold are predicted in terms of a weakly\nnonlinear perturbation analysis, which is confirmed by numerical simulations of\nthe basic model equations. The two relevant parameters determining the\nbifurcation scenario of the model can be related to the concentrations of the\nactive molecular motors and of the filaments respectively, which both could be\neasily regulated by the cell.",
        "positive": "Deformation and motion of giant unilamellar vesicles loaded with gold\n  nanoparticles driven by induced charge electro-osmotic flow: A vesicle is a spherical structure composed of a phospholipid bilayer that is\nused as a container for chemicals, both it in vivo and it in vitro systems. In\nboth cases, the vesicles can be passively moved using external molecular motors\nor flows. The active motion of the vesicles can potentially expand their\napplications in microfluid devices. In this study, we created giant unilamellar\nvesicles (GUVs) that loads dodecanethiol-functionalized gold nanoparticles\n(AuNPs) using natural swelling method. An external alternating current (AC)\nelectric field was applied to the sample to drive the system. A flow was\nconfirmed with dense optical flow method around GUVs, even in the absence of\nAuNPs. The quadratic dependence of the flow on applied elecric fields confirms\nthat the flow is due to induced charge electro-osmotic (ICEO) mechanism.\nFurthermore, the GUVs containing AuNPs moved and deformed significantly under\nexternal AC electric fields compared with those without AuNPs. We also\nconfirmed that the translational speed of GUVs was positively correlated with\nthe volume ratio of AuNPs. These experimental results suggest that the motion\nand deformation of GUVs were cause by ICEO flow, which was unbalanced owing to\nthe presence of localized AuNPs on the membrane."
    },
    {
        "anchor": "Molecular Dynamics Results on the Pressure Tensor of Polymer Films: Polymeric thin films of various thicknesses, confined between two repulsive\nwalls, have been studied by molecular dynamics simulations. Using the\nanisotropy of the perpendicular and parallel components of the pressure tensor\nthe surface tension of the system is calculated for a wide range of temperature\nand for various film thicknesses. Three methods of determining the pressure\ntensor are compared: the method of Irving and Kirkwood (IK), an approximation\nthereof (IK1), and the method of Harasima (H). The IK- and the H-methods differ\nin the expression for the parallel component, but not for the normal component\nof the pressure tensor. Both methods yield a constant normal component\nthroughout the film, as required by mechanical stability, whereas the\nIK1-method leads to strong oscillations. However, all methods give the same\nexpression for the surface tension.",
        "positive": "Lattice Model for Production of Gas: We define a lattice model for rock, absorbers, and gas that makes it possible\nto examine the flow of gas to a complicated absorbing boundary over long\nperiods of time. The motivation is to deduce the geometry of the boundary from\nthe time history of gas absorption. We find a solution to this model using\nGreen's function techniques, and apply the solution to three absorbing networks\nof increasing complexity."
    },
    {
        "anchor": "Electrostatic interactions mediated by polarizable counterions: weak and\n  strong coupling limits: We investigate the statistical mechanics of an inhomogeneous Coulomb fluid\ncomposed of charged particles with static polarizability. We derive the weak-\nand the strong-coupling approximations and evaluate the partition function in a\nplanar dielectric slab geometry with charged boundaries. We investigate the\ndensity profiles and the disjoining pressure for both approximations.\nComparison to the case of non-polarizable counterions shows that polarizability\nbrings important differences in the counterion density distribution as well as\nthe counterion mediated electrostatic interactions between charged dielectric\ninterfaces.",
        "positive": "Adhesion-induced Phase Separation of Biomembranes--Effective Potential\n  and Simulations: We present theoretical analyses and numerical simulations for the\nadhesion-induced phase separation of multi-component membranes with two types\nof ligand-receptor complexes (junctions). We show that after integrating all\npossible distributions of the junctions, the system can be regarded as a\nmembrane under an effective external potential. Mean field theory and Gaussian\napproximation are used to analyze the effective membrane potential and we find\n(i) The height difference of the junctions is the main factor that drives phase\nseparation at sufficiently large junction height difference. (ii) In the two\nphase region far from the mean-field critical point, because of the higher\nentropy associated with the softer junctions, phase coexistence occurs when the\neffective binding energy of the more rigid junctions is higher. (iii) In the\ntwo phase region near the mean-field critical point, the shape of the effective\npotential shows that the phase coexistence occurs when the effective binding\nenergy of softer junctions is higher. The effect of junction density on the\ncritical point is studied by Monte Carlo simulations, and the result shows that\nphase separation occurs at larger junction height difference as junction\ndensity of the system decreases."
    },
    {
        "anchor": "Ageing and Rheology in Soft Materials: We study theoretically the role of ageing in the rheology of soft materials.\nWe define several generalized rheological response functions suited to ageing\nsamples (in which time translation invariance is lost). These are then used to\nstudy ageing effects within a simple scalar model (the \"soft glassy rheology\"\nor SGR model) whose constitutive equations relate shear stress to shear strain\namong a set of elastic elements, with distributed yield thresholds, undergoing\nactivated dynamics governed by a \"noise temperature\", $x$. (Between yields,\neach element follows affinely the applied shear.) For $1<x<2$ there is a\npower-law fluid regime in which transients occur, but no ageing. For $x<1$, the\nmodel has a macroscopic yield stress. So long as this yield stress is not\nexceeded, ageing occurs, with a sample's apparent relaxation time being of\norder its own age. The (age-dependent) linear viscoelastic loss modulus\n$G''(\\omega,t)$ rises as frequency is {\\em lowered}, but falls with age $t$, so\nas to always remain less than $G'(\\omega,t)$ (which is nearly constant).\nSignificant ageing is also predicted for the stress overshoot in nonlinear\nshear startup and for the creep compliance. Though obviously oversimplified,\nthe SGR model may provide a valuable paradigm for the experimental and\ntheoretical study of rheological ageing phenomena in soft solids.",
        "positive": "Homogenization approach to the behavior of suspensions of noncolloidal\n  particles in yield stress fluids: The behavior of suspensions of rigid particles in a non-Newtonian fluid is\nstudied in the framework of a nonlinear homogenization method. Estimates for\nthe overall properties of the composite material are obtained. In the case of a\nHerschel-Bulkley suspending fluid, it is shown that the properties of a\nsuspension with overall isotropy can be satisfactory modeled as that of a\nHerschel-Bulkley fluid with an exponent equal to that of the suspending fluid.\nEstimates for the yield stress and the consistency at large strain rate levels\nare proposed. These estimates compare well to both experimental data obtained\nby Mahaut et al [J. Rheol. 52, 287-313 (2008)] and to experimental data found\nin the literature."
    },
    {
        "anchor": "Generalized fluctuation-dissipation relation and effective temperature\n  in off-equilibrium colloids: The fluctuation-dissipation relation (FDR), a fundamental result of\nequilibrium statistical physics, ceases to be valid when a system is taken out\nof the equilibrium. A generalization of FDR has been theoretically proposed for\nout-of-equilibrium systems: the kinetic temperature entering FDR is substituted\nby a time-scale dependent effective temperature. We combine the measurements of\nthe correlation function of the rotational dynamics of colloidal particles\nobtained via dynamic light scattering with those of the birefringence response\nto study the generalized FDR in an off-equilibrium clay suspension undergoing\naging. We i) find that FDR is strongly violated in the early stage of the aging\nprocess and is gradually recovered as the aging time increases and, ii), we\ndetermine the aging time evolution of the effective temperature, giving support\nto the proposed generalization scheme.",
        "positive": "Johari-Goldstein $\u03b2$ relaxation in glassy dynamics originates from\n  two-scale energy landscape: Supercooled liquids undergo complicated structural relaxation processes,\nwhich have been a long-standing problem in both experimental and theoretical\naspects of condensed matter physics. In particular, past experiments\nuniversally observed for many types of molecular liquids that relaxation\ndynamics separated into two distinct processes at low temperatures. One of the\npossible interpretations is that this separation originates from the two-scale\nhierarchical topography of the potential energy landscape; however, it has\nnever been verified. Molecular dynamics simulations are a promising approach to\ntackle this issue, but we must overcome laborious difficulties. First, we must\nhandle a model of molecular liquids that is computationally demanding compared\nto simple spherical models, which have been intensively studied but show only a\nslower process: $\\alpha$ relaxation. Second, we must reach a sufficiently\nlow-temperature regime where the two processes become well separated. Here, we\nhandle an asymmetric dimer system that exhibits a faster process:\nJohari-Goldstein $\\beta$ relaxation. Then, we employ the parallel tempering\nmethod to access the low-temperature regime. These laborious efforts enable us\nto investigate the potential energy landscape in detail and unveil the first\ndirect evidence of the topographic hierarchy that induces the $\\beta$\nrelaxation. We also successfully characterize the microscopic motions of\nparticles during each relaxation process. Finally, we study the predictive\npower of low-frequency modes for two relaxation processes. Our results\nestablish for the first time a fundamental and comprehensive understanding of\nexperimentally observed relaxation dynamics in supercooled liquids."
    },
    {
        "anchor": "Analytical model for flux saturation in sediment transport: The transport of sediment by a fluid along the surface is responsible for\ndune formation, dust entrainment and for a rich diversity of patterns on the\nbottom of oceans, rivers, and planetary surfaces. Most previous models of\nsediment transport have focused on the equilibrium (or saturated) particle\nflux. However, the morphodynamics of sediment landscapes emerging due to\nsurface transport of sediment is controlled by situations out-of-equilibrium.\nIn particular, it is controlled by the saturation length characterizing the\ndistance it takes for the particle flux to reach a new equilibrium after a\nchange in flow conditions. The saturation of mass density of particles\nentrained into transport and the relaxation of particle and fluid velocities\nconstitute the main relevant relaxation mechanisms leading to saturation of the\nsediment flux. Here we present a theoretical model for sediment transport\nwhich, for the first time, accounts for both these relaxation mechanisms and\nfor the different types of sediment entrainment prevailing under different\nenvironmental conditions. Our analytical treatment allows us to derive a closed\nexpression for the saturation length of sediment flux, which is general and can\nthus be applied under different physical conditions.",
        "positive": "The competition between surface adsorption and folding of fibril-forming\n  polypeptides: Self-assembly of polypeptides into fibrillar structures can be initiated by\nplanar surfaces that interact favorably with certain residues. Using a coarse\ngrained model, we systematically studied the folding and adsorption behavior of\na $\\beta$-roll forming polypeptide. We find that there are two different\nfolding pathways depending on the temperature: (i) at low temperature, the\npolypeptide folds in solution into a $\\beta$-roll before adsorbing onto the\nattractive surface, (ii) at higher temperature, the polypeptide first adsorbs\nin a disordered state, and folds while on the surface. The folding temperature\nincreases with increasing attraction, as the folded $\\beta$-roll is stabilized\nby the surface. Surprisingly, further increasing the attraction lowers the\nfolding temperature again, as strong attraction also stabilizes the adsorbed\ndisordered state, which competes with folding of the polypeptide. Our results\nsuggest that to enhance the folding, one should use a weakly attractive\nsurface. They also explain the recent experimental observation of the\nnon-monotonic effect of charge on the fibril formation on an oppositely charged\nsurface [C. Charbonneau, et al., ACS Nano, 8, 2328 (2014)]."
    },
    {
        "anchor": "Boosting macroscopic diffusion with local resetting: Stochastic interactions generically enhance self-diffusivity in living and\nbiological systems, e.g. optimizing navigation strategies and controlling\nmaterial properties of cellular tissues and bacterial aggregates. Despite this,\nthe physical mechanisms underlying this nonequilibrium behavior are poorly\nunderstood. Here, we introduce a model of interactions between an agent and its\nenvironment in the form of a local stochastic resetting mechanism, in which the\nagent's position is set to the nearest of a predetermined array of sites with a\nfixed rate. We derive analytic results for the self-diffusion coefficient,\nshowing explicitly that this mechanism enhances diffusivity. Strikingly, we\nshow analytically that this enhancement is optimized by regular arrays of\nresetting sites. Altogether, our results ultimately provide the conditions for\nthe optimization of the macroscopic transport properties of diffusive systems\nwith local random binding interactions.",
        "positive": "Early stage of Erythrocyte Sedimentation Rate test: Fracture of a\n  high-volume-fraction gel: Erythrocyte Sedimentation Rate (ESR) is a clinical parameter used as a\nnon-specific marker for inflammation, and recent studies have shown that it is\nlinked to the collapse of the gel formed by red blood cells (RBCs) at\nphysiological hematocrits (i.e. RBC volume fraction). Previous research has\nsuggested that the delay time before the sedimentation process is related to\nthe formation of fractures in the gel. Moreover, RBC gels present specific\nproperties due to the anisotropic shape and flexibility of the RBCs. Namely,\nthe onset of the collapse is reached earlier and the settling velocity of the\ngel increases with increasing attraction between the RBCs, while gel of\nspherical particles show the opposite trend. Here, we report experimental\nobservations of the gel structure during this onset and suggest an equation\nmodeling this initial process as fracturing of the gel. We demonstrate that\nthis equation provides a model for the motion of the interface between blood\nplasma and the RBC gel, along the whole time span. We also observe that the\nincrease in the attraction between the RBCs modifies the density of fractures\nin the gel, which explains why the gel displays a decrease in delay time when\nthe aggregation energy between the RBCs increases. Our work uncovers the\ndetailed physical mechanism underlying the ESR and provides insights into the\nfracture dynamics of a RBC gel. These results can improve the accuracy of\nclinical measurements."
    },
    {
        "anchor": "Vortex state in a superfluid Fermi gas near a Feshbach resonance: We consider a single vortex in a superfluid Fermi gas in the BCS-BEC\ncrossover regime near a Feshbach resonance. The effect of the molecular\nBose-Einstein condensate upon the vortex structure is discussed within the mean\nfield approximation at zero temperature. Using the self-consistent\nBogoliubov-de Gennes equation of the fermion-boson coupled model, we calculate\ndensity distributions of atoms and molecules. As the number of the molecules\nincreases, both atomic and molecular density changes from BCS-like distribution\nto BEC-like. We also study the change of the vortex core size in the crossover\nregime.",
        "positive": "Global analysis of the ground-state wrapping conformation of a charged\n  polymer on an oppositely charged nano-sphere: We investigate the wrapping conformations of a strongly adsorbed polymer\nchain on an oppositely charged nano-sphere by employing a reduced\n(dimensionless) representation of a primitive chain-sphere model. This enables\nus to determine the global phase behavior of the chain conformation in a wide\nrange of values for the system parameters including the chain contour length,\nits linear charge density and persistence length as well as the nano-sphere\ncharge and radius, and also the salt concentration in the bathing solution. The\nphase behavior of a charged chain-sphere complex can be described in terms of a\nfew distinct conformational symmetry classes (phases) separated by continuous\nor discontinuous transition lines which are determined by means of\nappropriately defined (order) parameters. Our results can be applied to a wide\nclass of strongly coupled polymer-sphere complexes including, for instances,\ncomplexes that comprise a mechanically flexible or semiflexible polymer chain\nor an extremely short or long chain and, as a special case, include the\npreviously studied example of DNA-histone complexes."
    },
    {
        "anchor": "Repton model of gel electrophoresis in the long chain limit: Reptation governs motion of long polymers through a confining environment.\nSlack enters at the ends and diffuses along the polymer as stored length. The\nrate at which stored length diffuses limits the speed at which the chain can\ndrift. This paper relates the rate of stored length diffusion to the\nconformation of the tube within which the polymer is confined. In the scaling\nlimit of long polymer chains and weak applied electric fields, holding the\nproduct of polymer length times field finite, the tube length and stored length\ndensity take on their zero-field values. The drift velocity then depends only\non the the polymer's end-to-end separation in the direction of the field.",
        "positive": "Two-Component Fluid Membranes Near Repulsive Walls: Linearized\n  Hydrodynamics of Equilibrium and Non-equilibrium States: We study the linearized hydrodynamics of a two-component fluid membrane near\na repulsive wall, via a model which incorporates curvature- concentration\ncoupling as well as hydrodynamic interactions. This model is a simplified\nversion of a recently proposed one [J.-B. Manneville et al. Phys. Rev. E, 64,\n021908 (2001)] for non-equilibrium force-centres embedded in fluid membranes,\nsuch as light-activated bacteriorhodopsin pumps incorporated in phospholipid\n(EPC) bilayers. The pump/membrane system is modeled as an impermeable,\ntwo-component bilayer fluid membrane in the presence of an ambient solvent, in\nwhich one component, representing active pumps, is described in terms of force\ndipoles displaced with respect to the bilayer midpoint. We first discuss the\ncase in which such pumps are rendered inactive, computing the mode structure in\nthe bulk as well as the modification of hydrodynamic properties by the presence\nof a nearby wall. We then discuss the fluctuations and mode structure in steady\nstate of active two-component membranes near a repulsive wall. We find that\nproximity to the wall smoothens membrane height fluctuations in the stable\nregime, resulting in a logarithmic scaling of the roughness even for initially\ntensionless membranes. This explicitly non-equilibrium result, a consequence of\nthe incorporation of curvature-concentration coupling in our treatment, also\nindicates that earlier scaling arguments which obtained an increase in the\nroughness of active membranes near repulsive walls may need to be reevaluated."
    },
    {
        "anchor": "NVU perspective on simple liquids' quasiuniversality: The last half century of research into the structure, dynamics, and\nthermodynamics of simple liquids has revealed a number of approximate\nuniversalities. This paper argues that simple liquids' reduced-coordinate\nconstant-potential-energy hypersurfaces constitute a quasiuniversal family of\ncompact Riemannian manifolds parameterized by a single number, from which\nfollows these liquids' quasiuniversalities.",
        "positive": "Hunting Mermaids in Real Space: Known Knowns, Known Unknowns and Unknown\n  Unknowns: We review efforts to realise so-called mermaid (or short-ranged\nattraction/long ranged repulsion) interactions in 3d real space. The repulsive\nand attractive contributions to these interactions in charged colloids and\ncolloid-polymer mixtures, may be accurately realised, by comparing\nparticle-resolved studies with colloids to computer simulation. However, when\nwe review work where these interactions have been combined, despite early\nindications of behaviour consistent with predictions, closer analysis reveals\nthat in the non-aqueous systems used for particle-resolved studies, the idea of\nsumming the attractive and repulsive components leads to wild deviations with\nexperiment. We suggest that the origin lies in the weak ion dissociation in\nthese systems with low dielectric constant solvents. Ultimately this leads even\nto non-centro-symmetric interactions and a new level of complexity in these\nsystems."
    },
    {
        "anchor": "Semiflexible polymer conformation, distribution and migration in\n  microcapillary flows: The flow behavior of a semiflexible polymer in microchannels is studied using\nMultiparticle Collision Dynamics (MPC), a particle-based hydrodynamic\nsimulation technique. Conformations, distributions, and radial cross-streamline\nmigration are investigated for various bending rigidities, with persistence\nlengths Lp in the range 0.5 < Lp/Lr < 30. The flow behavior is governed by the\ncompetition between a hydrodynamic lift force and steric wall-repulsion, which\nlead to migration away from the wall, and a locally varying flow-induced\norientation, which drives polymer away from the channel center and towards the\nwall. The different dependencies of these effects on the polymer bending\nrigidity and the flow velocity results in a complex dynamical behavior.\nHowever, a generic effect is the appearance of a maximum in the monomer and the\ncenter-of-mass distributions, which occurs in the channel center for small flow\nvelocities, but moves off-center at higher velocities.",
        "positive": "Glassy dynamics and dynamical heterogeneity in colloids: Concentrated colloidal suspensions are a well-tested model system which has a\nglass transition. Colloids are suspensions of small solid particles in a\nliquid, and exhibit glassy behavior when the particle concentration is high;\nthe particles are roughly analogous to individual molecules in a traditional\nglass. Because the particle size can be large (100 nm - 1000 nm), these samples\ncan be studied with a variety of optical techniques including microscopy and\ndynamic light scattering. Here we review the phenomena associated with the\ncolloidal glass transition, and in particular discuss observations of spatial\nand temporally heterogeneous dynamics within colloidal samples near the glass\ntransition. Although this Chapter focuses primarily on results from\nhard-sphere-like colloidal particles, we also discuss other colloidal systems\nwith attractive or soft repulsive interactions."
    },
    {
        "anchor": "Anisotropic swelling of anisotropic elastic panels: While isotropic in-plane swelling problems for thin elastic sheets have been\nstudied extensively in recent years, many shape-programmable materials,\nincluding nematic solids and 3D-printed structures, are anisotropic, as are\nmost industrial sheet materials. In this theoretical work, we consider central\nswelling and shrinkage of plates of aspect ratio and material properties\nrelevant to the manufacture of engineered wood composite panels in which both\nin-plane swelling and material stiffness are highly orthotropic, leading to\nmultiple separations in energy scales. With transverse swelling in the soft\ndirection, and gradients in the stiff direction, the warped plates adopt two\ndistinct types of configurations, axisymmetric and twisted, which we illustrate\nwith toy models. We employ a two-parameter family of isometries to embed the\nmetric programmed by the swelling, thus reducing the problem to one of\nminimizing bending energy alone. A simple argument is seen to closely predict\naveraged axisymmetric curvatures. While purely cylindrical shapes are\nunobtainable by pure in-plane swelling, they can be closely approximated in a\nhighly anisotropic system. However, anisotropy can favor twisting, and breaks a\ndegenerate soft deformation mode associated with minimal surfaces in isotropic\nmaterials. Bifurcations from axisymmetric to twisted shapes can be induced by\nanisotropy or by certain attributes of a central shrinkage profile. Finally, we\nnote how our findings indicate practical limitations on the diagnosis of\nmoisture inhomogeneities in manufactured panels by observation of warped\nconformations, due to the sensitivity of the qualitative response to specifics\nof the profile.",
        "positive": "Why polymer chains in a melt are not random walks: A cornerstone of modern polymer physics is the `Flory ideality hypothesis'\nwhich states that a chain in a polymer melt adopts `ideal' random-walk-like\nconformations. Here we revisit theoretically and numerically this pivotal\nassumption and demonstrate that there are noticeable deviations from ideality.\nThe deviations come from the interplay of chain connectivity and the\nincompressibility of the melt, leading to an effective repulsion between chain\nsegments of all sizes $s$. The amplitude of this repulsion increases with\ndecreasing $s$ where chain segments become more and more swollen. We illustrate\nthis swelling by an analysis of the form factor $F(q)$, i.e. the scattered\nintensity at wavevector $q$ resulting from intramolecular interferences of a\nchain. A `Kratky plot' of $q^2F(q)$ {\\em vs.} $q$ does not exhibit the plateau\nfor intermediate wavevectors characteristic of ideal chains. One rather finds a\nconspicuous depression of the plateau, $\\delta(F^{-1}(q)) = |q|^3/32\\rho$,\nwhich increases with $q$ and only depends on the monomer density $\\rho$."
    },
    {
        "anchor": "Packing Transitions in the Elastogranular Confinement of a Slender Loop: Confined thin structures are ubiquitous in nature. Spatial and length\nconstraints have led to a number of novel packing strategies at both the\nmicro-scale, as when DNA packages inside a capsid, and the macro-scale, seen in\nplant root development and the arrangement of the human intestinal tract. By\nvarying the arc length of an elastic loop injected into an array of\nmonodisperse, soft, spherical grains at varying initial number density, we\ninvestigate the resulting packing behaviors between a growing slender structure\nconstrained by deformable boundaries. At low initial packing fractions, the\nelastic loop deforms as though it were hitting a flat surface by periodically\nfolding into the array. Above a critical packing fraction $\\phi_c$, local\nre-orientations within the granular medium create an effectively curved surface\nleading to the emergence of a distinct circular packing morphology in the\nadjacent elastic structure. These results will bring new insight into the\npacking behavior of wires and thin sheets and will be relevant to modeling\nplant root morphogenesis, burrowing and locomotive strategies of vertebrates &\ninvertebrates, and developing smart, steerable needles.",
        "positive": "Geometrically Reduced Number of Protein Ground State Candidates: Geometrical properties of protein ground states are studied using an\nalgebraic approach. It is shown that independent from inter-monomer\ninteractions, the collection of ground state candidates for any folded protein\nis unexpectedly small: For the case of a two-parameter Hydrophobic-Polar\nlattice model for $L$-mers, the number of these candidates grows only as $L^2$.\nMoreover, the space of the interaction parameters of the model breaks up into\nwell-defined domains, each corresponding to one ground state candidate, which\nare separated by sharp boundaries. In addition, by exact enumeration, we show\nthere are some sequences which have one absolute unique native state. These\nabsolute ground states have perfect stability against change of inter-monomer\ninteraction potential."
    },
    {
        "anchor": "Swarming bottom feeders: Flocking at solid-liquid interfaces: We present the hydrodynamic theory of coherent collective motion (\"flocking\")\nat a solid-liquid interface, and many of its predictions for experiment. We\nfind that such systems are stable, and have long-range orientational order,\nover a wide range of parameters. When stable, these systems exhibit \"giant\nnumber fluctuations\", which grow as the 3/4th power of the mean number. Stable\nsystems also exhibit anomalous rapid diffusion of tagged particles suspended in\nthe passive fluid along any directions in a plane parallel to the solid-liquid\ninterface, whereas the diffusivity along the direction perpendicular to the\nplane is not anomalous. In the remaining parameter space, the system becomes\nunstable.",
        "positive": "How does an external electric field trigger the Cassie-Baxter-Wenzel\n  wetting transition on a textured surface?: Understanding the critical condition and mechanism of the droplet wetting\ntransition between Cassie-Baxter state and Wenzel state triggered by an\nexternal electric field is of considerable importance because of its numerous\napplications in industry and engineering. However, such a wetting transition on\na patterned surface is still not fully understood, e.g., the effects of\nelectro-wetting number, geometry of the patterned surfaces, and droplet volume\non the transition have not been systematically investigated. In this paper, we\npropose a theoretical model for the Cassie-Baxter- Wenzel wetting transition\ntriggered by applying an external voltage on a droplet placed on a\nmircopillared surface or a porous substrate. It is found that the transition is\nrealized by lowering the energy barrier created by the intermediate composite\nstate considerably, which enables the droplet to cross the energy barrier and\ncomplete the transition process. Our calculations also indicate that for fixed\ndroplet volume, the critical electrowetting number (voltage) will increase\n(decrease) along with the surface roughness for a micro-pillar patterned\n(porous) surface, and if the surface roughness is fixed, a small droplet tends\nto ease the critical electrowetting condition for the transition. Besides,\nthree dimensional phase diagrams in terms of electrowetting number, surface\nroughness, and droplet volume are constructed to illustrate the\nCassie-Baxter-Wenzel wetting transition. Our theoretical model can be used to\nexplain the previous experimental results about the Cassie-Baxter-Wenzel\nwetting transition reported in the literature."
    },
    {
        "anchor": "Odd moduli of disordered odd elastic lattices: We study the effects of bond disorder on triangular and honeycomb lattices\nwhere each spring has a probability p to be odd elastic. Using an effective\nmedium theory and numerical simulations, we uncover the behavior of odd moduli\nin the presence of disorder, which we interpret as a crossover between the\naffine response of the passive elastic backbone, and a rigidity percolation\ntransition in the odd elastic components. Though oddness is generally robust\nagainst disorder even at low p, we find that fine-tuned features of an odd\nelastic honeycomb lattice are not robust against disorder.",
        "positive": "An Atomistic First-Principles Density Functional Theory Model for Single\n  Layer Dry \\textit{Stratum Corneum}: Many questions concerning the biophysical and physiological properties of\nskin are still open. Skin aging, permeability, dermal absorption, hydration and\ndrug transdermal delivery, are few examples of processes with its underlying\nmechanisms unveiled. In this work we present a first-principles density\nfunctional quantum atomistic model for single layer stratum corneum (SC) in\norder to contribute to unveil the molecular interactions behind the skin\nproperties at this scale. The molecular structure of SC was modeled by an\narchetype of its hygroscopic proteic portion inside of the corneocytes, the\nnatural moisturizing factor (NMF), coupled to glycerol molecules which\nrepresent the lipid fraction of SC. The vibrational spectra was calculated and\ncompared to Fourier-Transform Infrared Absorption spectroscopy (FTIR)\nexperimental data obtained on animal model of SC. We noticed that bands in the\nfingerprint region (800-1800 cm$^{-1}$) were correctly assigned. Moreover, our\ncalculations revealed the existence of two coupled vibration between hydroxyl\ngroup of lipid and NMF methylene (1120 and 1160 cm$^{-1}$), which are of\nspecial interest since they probe the lipid-amino acid coupling. The model was\nalso able to predict the shear modulus of dry SC in excellent agreement with\nthe reported value on literature. Others physical/chemical properties could be\ncalculated exploring the chemical accuracy and molecular resolution of our\nmodel. Research in dermatology, cosmetology, and biomedical engineering in the\nspecific topics of drug delivery and/or mechanical properties of skin are\nexamples of fields that would potentially take advantage of our approach."
    },
    {
        "anchor": "Dual antagonistic role of motor proteins in fluidizing active networks: Cells accomplish diverse functions using the same molecular building blocks,\nfrom setting up cytoplasmic flows to generating mechanical forces. In\nparticular, transitions between these non-equilibrium states are triggered by\nregulating the expression and activity of cytoskeletal proteins. However, how\nthese proteins set the large-scale mechanics of the cytoskeleton and drive such\nnon-equilibrium phase transitions remain poorly understood. Here, we show that\na minimal network of biopolymers, molecular motors, and crosslinkers exhibits\ntwo distinct emergent behaviors depending on its composition, spontaneously\nflowing like an active fluid, or buckling like an active solid. Molecular\nmotors play a dual antagonistic role, fluidizing or stiffening the network\ndepending on the ATP concentration. By combining experiments, continuum theory,\nand chemical kinetics, we identify how to assemble materials with targeted\nactivity and elasticity by setting the concentrations of each component. Active\nand elastic stresses can be further manipulated in situ by light-induced pulses\nof motor activity, controlling the solid-to-fluid transition. These results\nhighlight how cytoskeletal stresses regulate the self-organization of living\nmatter and set the foundations for the rational design and control of active\nmaterials.",
        "positive": "Asymptotic analysis of stresses near a crack tip in a two dimensional\n  colloidal packing saturated with liquid: The consolidation of colloidal particles in drying colloidal dispersions is\ninfluenced by various factors such as particle size and shape, and\ninter-particle potential. The capillary pressure induced by the menisci, formed\nbetween the top layer of particles in the packed bed, compresses the bed of\nparticles while the constraints enforced by the boundaries result in tensile\nstresses in the packing. Presence of flaws or defects in the bed determines its\nultimate strength under such circumstances. In this study, we determine the\nasymptotic stress distribution around a flaw in a two dimensional colloidal\npacking saturated with liquid and compare the results with those obtained from\nthe full numerical solution of the problem. Using the Griffith's criterion for\nequilibrium cracks, we relate the critical capillary pressure at equilibrium to\nthe crack size and the mechanical properties of the packed bed. The analysis\nalso gives the maximum allowable flaw size for obtaining a crack free packing."
    },
    {
        "anchor": "Anyon-fermion mapping and applications to ultracold gases in tight\n  waveguides: The Fermi-Bose mapping method for one-dimensional (1D) Bose and Fermi gases\nwith zero-range interactions is generalized to an anyon-fermion mapping and\napplied to exact solution of several models of ultracold gases with anyonic\nexchange symmetry in tight waveguides: anyonic Calogero-Sutherland model,\nanyons with point hard core interaction (\"anyonic TG gas\"), and spin-aligned\nanyon gas with infinite zero-range odd-wave attractions (\"anyonic FTG gas\"). It\nis proved that for even $N\\ge 4$ there are states of the anyonic FTG gas on a\nring, with anyonic phase slips which are odd integral multiples of $\\pi/(N-1)$,\nof energy lower than that of the corresponding fermionic ground state. A\ngeneralization to a spinor Fermi gas state with anyonic symmetry under purely\nspatial exchange enables energy lowering by the same mechanism.",
        "positive": "Phase separation and rotor self-assembly in active particle suspensions: Adding a non-adsorbing polymer to passive colloids induces an attraction\nbetween the particles via the `depletion' mechanism. High enough polymer\nconcentrations lead to phase separation. We combine experiments, theory and\nsimulations to demonstrate that using active colloids (such as motile bacteria)\ndramatically changes the physics of such mixtures. First, significantly\nstronger inter-particle attraction is needed to cause phase separation.\nSecondly, the finite size aggregates formed at lower inter-particle attraction\nshow unidirectional rotation. These micro-rotors demonstrate the self assembly\nof functional structures using active particles. The angular speed of the\nrotating clusters scales approximately as the inverse of their size, which may\nbe understood theoretically by assuming that the torques exerted by the\noutermost bacteria in a cluster add up randomly. Our simulations suggest that\nboth the suppression of phase separation and the self assembly of rotors are\ngeneric features of aggregating swimmers, and should therefore occur in a\nvariety of biological and synthetic active particle systems."
    },
    {
        "anchor": "Chemotaxis and auto-chemotaxis of self-propelling artificial droplet\n  swimmers: Chemotaxis and auto-chemotaxis play an important role in many essential\nbiological processes. We present a self-propelling artificial swimmer system\nwhich exhibits chemotaxis as well as negative auto-chemotaxis. Oil droplets in\nan aqueous surfactant solution are driven by interfacial Marangoni flows\ninduced by micellar solubilization of the oil phase. We demonstrate that\nchemotaxis along micellar surfactant gradients can guide these swimmers through\na microfluidic maze. Similarly, a depletion of empty micelles in the wake of a\ndroplet swimmer causes negative autochemotaxis and thereby trail avoidance. We\nhave studied autochemotaxis quantitatively in a microfluidic device of\nbifurcating channels: Branch choices of consecutive swimmers are\nanticorrelated, an effect decaying over time due to trail dispersion. We have\nmodeled this process by a simple one-dimensional diffusion process and\nstochastic Langevin dynamics. Our results are consistent with a linear\nsurfactant gradient force and diffusion constants appropriate for micellar\ndiffusion, and provide a measure of autochemotactic feedback strength versus\nstochastic forces.",
        "positive": "Elasticity-based polymer sorting in active fluids: A Brownian dynamics\n  study: While the dynamics of polymer chains in equilibrium media is well understood\nby now, the polymer dynamics in active non-equilibrium environments can be very\ndifferent. Here we study the dynamics of polymers in a viscous medium\ncontaining self-propelled particles in two dimensions by using Brownian\ndynamics simulations. We find that the polymer center of mass exhibits a\nsuperdiffusive motion at short to intermediate times and the motion turns\nnormal at long times, but with a greatly enhanced diffusivity. Interestingly,\nthe long time diffusivity shows a non-monotonic behavior as a function of the\nchain length and stiffness. We analyze how the polymer conformation and the\naccumulation of the self-propelled particles, and therefore the directed motion\nof the polymer, are correlated. At the point of maximal polymer diffusivity,\nthe polymer has preferentially bent conformations maintained by the balance\nbetween the chain elasticity and the propelling force generated by the active\nparticles. We also consider the barrier crossing dynamics of actively-driven\npolymers in a double-well potential. The barrier crossing times are\ndemonstrated to have a peculiar non-monotonic dependence, related to that of\nthe diffusivity. This effect can be potentially utilized for sorting of\npolymers from solutions in \\textit{in vitro} experiments."
    },
    {
        "anchor": "Self-propelled running droplets on solid substrates driven by chemical\n  reactions: We study chemically driven running droplets on a partially wetting solid\nsubstrate by means of coupled evolution equations for the thickness profile of\nthe droplets and the density profile of an adsorbate layer. Two models are\nintroduced corresponding to two qualitatively different types of experiments\ndescribed in the literature. In both cases an adsorption or desorption reaction\nunderneath the droplets induces a wettability gradient on the substrate and\nprovides the driving force for droplet motion. The difference lies in the\nbehavior of the substrate behind the droplet. In case I the substrate is\nirreversibly changed whereas in case II it recovers allowing for a periodic\ndroplet movement (as long as the overall system stays far away from\nequilibrium). Both models allow for a non-saturated and a saturated regime of\ndroplet movement depending on the ratio of the viscous and reactive time\nscales. In contrast to model I, model II allows for sitting drops at high\nreaction rate and zero diffusion along the substrate. The transition from\nrunning to sitting drops in model II occurs via a super- or subcritical\ndrift-pitchfork bifurcation and may be strongly hysteretic implying a\ncoexistence region of running and sitting drops.",
        "positive": "Stabilization of colloidal suspensions by means of highly-charged\n  nanoparticles: We employ a novel Monte Carlo simulation scheme to elucidate the\nstabilization of neutral colloidal microspheres by means of highly-charged\nnanoparticles [V. Tohver et al., Proc. Natl. Acad. Sci. U.S.A. 98, 8950\n(2001)]. In accordance with the experimental observations, we find that small\nnanoparticle concentrations induce an effective repulsion that prevents\ngelation caused by the intrinsic van der Waals attraction between colloids.\nHigher nanoparticle concentrations induce an attractive potential which is,\nhowever, qualitatively different from the regular depletion attraction. We also\nshow how colloid-nanoparticle size asymmetry and nanoparticle charge can be\nused to manipulate the effective interactions."
    },
    {
        "anchor": "Stringlet Excitation Model of the Boson Peak: The boson peak (BP), a low-energy excess in the vibrational density of states\nover the phonon Debye contribution, is often identified as being a\ncharacteristic of amorphous solid materials. Despite decades of efforts, its\nmicroscopic origin still remains a mystery and a consensus on its theoretical\nderivation has not yet been achieved. Recently, it has been proposed, and\ncorroborated with simulations, that the BP might stem from intrinsic localized\nmodes which involve string-like excitations (\"stringlets\") having a\none-dimensional (1D) nature. In this work, we build on a theoretical framework\noriginally proposed by Lund that describes the localized modes as 1D vibrating\nstrings, but we specify the stringlet size distribution to be exponential, as\nobserved in independent simulation studies. We show that a generalization of\nthis framework provides an analytical prediction for the BP frequency\n$\\omega_{BP}$ in the temperature regime well below the glass transition\ntemperature in both 2D and 3D amorphous systems. The final result involves no\nfree parameters and is in quantitative agreement with prior simulation\nobservations. Additionally, this stringlet theory of the BP naturally\nreproduces the softening of the BP frequency upon heating and offers an\nanalytical explanation for the experimentally observed scaling with the shear\nmodulus in the glass state and changes in this scaling in simulations of\nglass-forming liquids, which are normally performed above the glass-transition\ntemperature, $T_g$. Finally, the theoretical analysis highlights the existence\nof a strong damping for the stringlet modes above $T_g$, which leads to a large\nlow-frequency contribution to the 3D vibrational density of states, observed in\nboth experiments and simulations.",
        "positive": "Electric double layer theory for room temperature ionic liquids on\n  charged electrodes: milestones and prospects: In this review, we shortly summarize the basic theoretical milestones\nachieved in the mean-field theory of room temperature ionic liquids (RTILs) on\ncharged electrodes since the publication of Kornyshev's seminal paper in 2007.\nWe pay special attention to the behavior of the differential capacitance\nprofile and the microscopic parameters of ions that can have substantial\ninfluence on it. Among them are parameters of short-range specific\ninteractions, ionic diameters, static polarizabilities, and permanent dipole\nmoments. We also discuss the recent \"nonlocal\" mean-field theories that can\ndescribe the overscreening behavior of the local ionic concentrations, as well\nas the crossover from overscreening to crowding."
    },
    {
        "anchor": "Sustaining dry surfaces under water: Rough surfaces immersed under water remain practically dry if the\nliquid-solid contact is on roughness peaks, while the roughness valleys are\nfilled with gas. Mechanisms that prevent water from invading the valleys are\nwell studied. However, to remain practically dry under water, additional\nmechanisms need consideration. This is because trapped gas (e.g. air) in the\nroughness valleys can dissolve into the water pool, leading to invasion.\nAdditionally, water vapor can also occupy the roughness valleys of immersed\nsurfaces. If water vapor condenses, that too leads to invasion. These effects\nhave not been investigated, and are critically important to maintain surfaces\ndry under water. In this work, we identify the critical roughness scale below\nwhich it is possible to sustain the vapor phase of water and/or trapped gases\nin roughness valleys - thus keeping the immersed surface dry. Theoretical\npredictions are consistent with molecular dynamics simulations and experiments.",
        "positive": "The weakly nonlinear response and non-affine interpretation of the\n  Johnson-Segalman/Gordon-Schowalter model: We derive new analytical solutions for the non-affine\nJohnson-Segalman/Gordon-Schowalter (JS/GS) constitutive equation with a general\nrelaxation kernel in medium-amplitude oscillatory shear (MAOS) deformation. The\nresults show time-strain separable (TSS) nonlinearity, therefore providing new\nphysically-meaningful interpretation to the heuristic TSS nonlinear parameter\nin MAOS (Martinetti & Ewoldt Phys. Fl. (2019)). The upper-convected,\nlower-convected, and corotational Maxwell models are all subsets of the results\npresented here. The model assumes that the microscale elements causing stress\nin the material slip compared to the continuum deformation. We introduce a\nvisualization of the non-affine deformation field that acts on\nstress-generating elements to reinforce the physical interpretation of the\nJS/GS class of models. Finally, a case study is presented where previously\npublished results, from fitting TSS models to MAOS data, can be re-interpreted\nbased on the concept of non-affine motion of the JS/GS framework."
    },
    {
        "anchor": "Counterion-Induced Swelling of Ionic Microgels: Ionic microgel particles, when dispersed in a solvent, swell to equilibrium\nsizes that are governed by a balance between electrostatic and elastic forces.\nTuning of particle size by varying external stimuli, such as $p$H, salt\nconcentration, and temperature, has relevance for drug delivery, microfluidics,\nand filtration. To model swelling of ionic microgels, we derive a statistical\nmechanical theorem, which proves exact within the cell model, for the\nelectrostatic contribution to the osmotic pressure inside a permeable colloidal\nmacroion. Applying the theorem, we demonstrate how the distribution of\ncounterions within an ionic microgel determines the internal osmotic pressure.\nBy combining the electrostatic pressure, which we compute via both\nPoisson-Boltzmann theory and molecular dynamics simulation, with the elastic\npressure, modeled via the Flory-Rehner theory of swollen polymer networks, we\nshow how deswelling of ionic microgels with increasing concentration of\nparticles can result from a redistribution of counterions that reduces\nelectrostatic pressure. A linearized approximation for the electrostatic\npressure, which proves remarkably accurate, provides physical insight and\ngreatly eases numerical calculations for practical applications. Comparing with\nexperiments, we explain why soft particles in deionized suspensions deswell\nupon increasing concentration and why this effect may be suppressed at higher\nionic strength. The failure of the uniform ideal-gas approximation to\nadequately account for counterion-induced deswelling below close packing of\nmicrogels is attributed to neglect of spatial variation of the counterion\ndensity profile and the electrostatic pressure of incompletely neutralized\nmacroions.",
        "positive": "Densest versus jammed packings of bent-core trimers: We identify putatively maximally dense packings of tangent-sphere trimers\nwith fixed bond angles ($\\theta = \\theta_0$) using a novel method, and contrast\nthem to the disordered jammed states they form under quasistatic and dynamic\nathermal compression. Incommensurability of $\\theta_0$ with 3D close-packing\ndoes not by itself inhibit formation of dense 3D crystals; all $\\theta_0$ allow\nformation of crystals with $\\phi_{max}(\\theta_0) > 0.97\\phi_{cp}$. Trimers are\nalways able to arrange into periodic structures composed of close-packed\nbilayers or trilayers of triangular-lattice planes, separated by ``gap layers''\nthat accomodate the incommensurability. All systems have $\\phi_J$ significantly\nbelow the monomeric value, indicating that trimers' quenched bond-length and\nbond-angle constraints always act to promote jamming. $\\phi_J$ varies strongly\nwith $\\theta_0$; straight ($\\theta_0 = 0$) trimers minimize $\\phi_J$ while\nclosed ($\\theta_0 = 120^\\circ$) trimers maximize it. Marginally jammed states\nof trimers with lower $\\phi_J(\\theta_0)$ exhibit quantifiably greater disorder,\nand the lower $\\phi_J$ for small $\\theta_0$ is apparently caused by trimers'\ndecreasing effective configurational freedom as they approach linearity."
    },
    {
        "anchor": "A Master equation for force distributions in polydisperse frictional\n  particles: An incremental evolution equation, i.e. a Master equation in statistical\nmechanics, is introduced for force distributions in polydisperse frictional\nparticle packings. As basic ingredients of the Master equation, the conditional\nprobability distributions of particle overlaps are determined by molecular\ndynamics simulations. Interestingly, tails of the distributions become much\nnarrower in the case of frictional particles than frictionless particles,\nimplying that correlations of overlaps are strongly reduced by microscopic\nfriction. Comparing different size distributions, we find that the tails are\nwider for the wider distribution.",
        "positive": "Effect of Ridge-Ridge Interactions in Crumpled Thin Sheets: We study whether and how the energy scalings based on the single-ridge\napproximation are revised in an actual crumpled sheet; namely, in the presence\nof ridge-ridge interactions. Molecular Dynamics Simulation is employed for this\npurpose. In order to improve the data quality, modifications are introduced to\nthe common protocol. As crumpling proceeds, we find that the average storing\nenergy changes from being proportional to one-third of the ridge length to a\nlinear relation, while the ratio of bending and stretching energies decreases\nfrom 5 to 2. The discrepancy between previous simulations and experiments on\nthe material-dependence for the power-law exponent is resolved. We further\ndetermine the averaged ridge length to scale linearly with the crumpled ball\nsize $R$, the ridge number as $1/R^2$, and the average storing energy per unit\nridge length as $1/R^{2.364\\sim 2.487}$. These results are consistent with the\nmean-field predictions. Finally, we extend the existent simulations to the\nhigh-pressure region for completeness, and verify the existence of a new\nscaling relation that is more general than the familiar power law at covering\nthe whole density range."
    },
    {
        "anchor": "Collective motion in a sheet of microswimmers: Self-propelled micron-size particles suspended in a fluid, like bacteria or\nsynthetic microswimmers, are strongly non-equilibrium systems where particle\nmotility breaks the microscopic detailed balance, often resulting in\nlarge-scale collective motion. Previous theoretical work has identified\nlong-range hydrodynamic interactions as the main driver of collective motion in\nunbounded dilute suspension of rear-actuated (\"pusher\") microswimmers. In\ncontrast, most experimental studies of collective motion in microswimmer\nsuspensions have been carried out in quasi-2-dimensional geometries such as in\nthin films or near solid or fluid interfaces, where both the swimmers' motion\nand their long-range flow fields become altered due to the proximity of a\nboundary. Here, we study numerically a minimal model of microswimmers in such a\nrestricted geometry, where the particles move in the midplane between two\nno-slip walls. For pushers, we demonstrate collective motion with only\nshort-ranged order, in contrast with the long-ranged flows observed in\nunbounded systems. For front-actuated (\"puller\") microswimmers, we discover a\nlong-wavelength density instability resulting in the formation of dense\nmicroswimmer clusters. Both types of collective motion are fundamentally\ndifferent from their previously studied counterparts in unbounded domains. Our\nresults illustrate that hydrodynamic screening due to the presence of a wall is\nsubdominant in determining the collective state of the suspension, which is\ninstead dictated by the geometrical restriction of the swimmers' motion.",
        "positive": "Cooperativity of short-time dynamics revisited: Using molecular dynamics simulations we examine the system size dependence of\nthe fast dynamics in two model glass forming liquids, one of them a\nLennard-Jones mixture for which cooperative fast relaxation has been reported.\nWe find no indication of a temperature-dependent dynamic length scale\ncharacterizing these fast dynamics; the size effects in the short time range\nare temperature independent, and the consequence of cutting off of long\nwavelength acoustic modes. In a molecular liquid exhibiting a clear\nJohari-Goldstein (JG) relaxation, significant size effects are again present\nboth for the vibrational motion and long-time {\\alpha} relaxation (only the\nlatter having a significant temperature dependence), but absent for the JG\nrelaxation."
    },
    {
        "anchor": "Grain Scale Modeling of Arbitrary Fluid Saturation in Random Packings: We propose a model for increasing liquid saturation in a granular packing\nwhich can account for liquid redistribution at saturation levels beyond the\nwell-studied capillary bridge regime. The model is capable of resolving and\ncombining capillary bridges, menisci and fully saturated pores to form local\nliquid clusters of any shape. They can exchange volume due to the local Laplace\npressure gradient via a liquid film on the surfaces of grains. Local\ninstabilities like Haines jumps trigger the discontinuous evolution of the\nliquid front. The applicability of the model is demonstrated and compared to\nbenchmark experiments on the level of individual liquid structures as well as\non larger systems.",
        "positive": "Speckle Tweezers for Simultaneous Controlling of Low and High Refractive\n  Index Micro-particles: Manipulation of micro and nanoscale particles suspended in a fluidic medium\nis one among the defining goals of modern nanotechnology. Speckle tweezers (ST)\nby incorporating randomly distributed light fields have been used to apply\ndetectable limits on the Brownian motion of micro-particles with refractive\nindices higher than their medium. Indeed, compared to periodic potentials, ST\nrepresents a wider possibility to be operated for such tasks. Here, we extend\nthe usefulness of ST into low index micro-particles. Repelling of such\nparticles by high intensity regions into lower intensity regions makes them to\nbe locally confined, and the confinement can be tuned by changing the average\ngrain intensity and size of the speckle patterns. Experiments on polystyrenes\nand liposomes validate the procedure. Moreover, we show that ST can be used to\nnano-particle (NP)-loaded liposomes. Interestingly, the different interactions\nof NP-loaded and empty liposomes with ST enables collective manipulation of\ntheir mixture using the same speckle pattern, which may be explained by\ninclusion of the photophoretic forces on NPs in NP-loaded liposomes. Our\nresults on the different behavior between empty and non-empty vesicles may open\na new window on controlling collective transportation of drug micro-containers\nalong with its wide applications in soft matter."
    },
    {
        "anchor": "Tangentially Driven Active Polar Linear Polymers -- An Analytical Study: The conformational and dynamical properties of isolated flexible active polar\nlinear polymers (APLPs) are studied analytically. The APLPs are modeled as\nGaussian bead-spring linear chains augmented by tangential active forces, both\nin a discrete and continuous representations. The polar forces lead to linear\nnon-Hermitian equations of motion, which are solved by an eigenfunction\nexpansion in terms of a biorthogonal basis set. Our calculations show that the\npolymer conformations are independent of activity. On the contrary, tangential\npropulsion strongly impacts the polymer dynamics and yields an active ballistic\nregime as well as activity-enhanced long-time diffusion, regimes which are both\nabsent in passive systems. The polar forces imply a coupling of modes in the\neigenfunction representation, in particular with the translational mode, with a\nrespective strong influence on the polymer dynamics. The total polymer\nmean-square displacement on scales smaller than their radius of gyration is\ndetermined by the active internal dynamics rather than the collective\ncenter-of-mass motion, in contrast to active Brownian polymers, reflecting the\ndistinct difference in the propulsion mechanism.",
        "positive": "Criterion for purely elastic Taylor-Couette instability in the flows of\n  shear-banding fluids: In the past twenty years, shear-banding flows have been probed by various\ntechniques, such as rheometry, velocimetry and flow birefringence. In micellar\nsolutions, many of the data collected exhibit unexplained spatio-temporal\nfluctuations. Recently, it has been suggested that those fluctuations originate\nfrom a purely elastic instability of the flow. In cylindrical Couette geometry,\nthe instability is reminiscent of the Taylor-like instability observed in\nviscoelastic polymer solutions. In this letter, we describe how the criterion\nfor purely elastic Taylor-Couette instability should be adapted to\nshear-banding flows. We derive three categories of shear-banding flows with\ncurved streamlines, depending on their stability."
    },
    {
        "anchor": "Structural Relaxation and Mode Coupling in a Simple Liquid: Depolarized\n  Light Scattering in Benzene: We have measured depolarized light scattering in liquid benzene over the\nwhole accessible temperature range and over four decades in frequency. Between\n40 and 180 GHz we find a susceptibility peak due to structural relaxation. This\npeak shows stretching and time-temperature scaling as known from $\\alpha$\nrelaxation in glass-forming materials. A simple mode-coupling model provides\nconsistent fits of the entire data set. We conclude that structural relaxation\nin simple liquids and $\\alpha$ relaxation in glass-forming materials are\nphysically the same. A deeper understanding of simple liquids is reached by\napplying concepts that were originally developed in the context of\nglass-transition research.",
        "positive": "Mesoscopic models for DNA stretching under force: new results and\n  comparison to experiments: Single molecule experiments on B-DNA stretching have revealed one or two\nstructural transitions, when increasing the external force. They are\ncharacterized by a sudden increase of DNA contour length and a decrease of the\nbending rigidity. It has been proposed that the first transition, at forces of\n60--80 pN, is a transition from B to S-DNA, viewed as a stretched duplex DNA,\nwhile the second one, at stronger forces, is a strand peeling resulting in\nsingle stranded DNAs (ssDNA), similar to thermal denaturation. But due to\nexperimental conditions these two transitions can overlap, for instance for\npoly(dA-dT). We derive analytical formula using a coupled discrete worm like\nchain-Ising model. Our model takes into account bending rigidity, discreteness\nof the chain, linear and non-linear (for ssDNA) bond stretching. In the limit\nof zero force, this model simplifies into a coupled model already developed by\nus for studying thermal DNA melting, establishing a connexion with previous\nfitting parameter values for denaturation profiles. We find that: (i) ssDNA is\nfitted, using an analytical formula, over a nanoNewton range with only three\nfree parameters, the contour length, the bending modulus and the monomer size;\n(ii) a surprisingly good fit on this force range is possible only by choosing a\nmonomer size of 0.2 nm, almost 4 times smaller than the ssDNA nucleobase\nlength; (iii) mesoscopic models are not able to fit B to ssDNA (or S to ss)\ntransitions; (iv) an analytical formula for fitting B to S transitions is\nderived in the strong force approximation and for long DNAs, which is in\nexcellent agreement with exact transfer matrix calculations; (v) this formula\nfits perfectly well poly(dG-dC) and $\\lambda$-DNA force-extension curves with\nconsistent parameter values; (vi) a coherent picture, where S to ssDNA\ntransitions are much more sensitive to base-pair sequence than the B to S one,\nemerges."
    },
    {
        "anchor": "Predicting and assessing rupture in protein gels under oscillatory shear: Soft materials may break irreversibly upon applying sufficiently large shear\noscillations, a process which physical mechanism remains largely elusive. In\nthis work, the rupture of protein gels made of sodium caseinate under an\noscillatory stress is shown to occur in an abrupt, brittle-like manner. Upon\nincreasing the stress amplitude, the build-up of harmonic modes in the strain\nresponse can be rescaled for all gel concentrations. This rescaling yields an\nempirical criterion to predict the rupture point way before the samples are\nsignificantly damaged. \"Fatigue\" experiments under stress oscillations of\nconstant amplitude can be mapped onto the former results, which indicates that\nrupture is independent of the temporal pathway in which strain and damage\naccumulate. Finally, using ultrasonic imaging, we measure the local mechanical\nproperties of the gels before, during and after breakdown, showing that the\nstrain field remains perfectly homogeneous up to rupture but suddenly gives way\nto a solid-fluid phase separation upon breakdown.",
        "positive": "Theoretical Model for Faraday Waves with Multiple-Frequency Forcing: A simple generalization of the Swift-Hohenberg equation is proposed as a\nmodel for the pattern-forming dynamics of a two-dimensional field with two\nunstable length scales. The equation is used to study the dynamics of surface\nwaves in a fluid driven by a linear combination of two frequencies. The model\nexhibits steady-state solutions with two-, four-, six-, and twelve-fold\nsymmetric patterns, similar to the periodic and quasiperiodic patterns observed\nin recent experiments."
    },
    {
        "anchor": "SPIRAL: An Efficient Algorithm for the Integration of the Equation of\n  Rotational Motion: We introduce Spiral, a third-order integration algorithm for the rotational\nmotion of extended bodies. It requires only one force calculation per time\nstep, does not require quaternion normalization at each time step, and can be\nformulated for both leapfrog and synchronous integration schemes, making it\ncompatible with many particle simulation codes. The stability and precision of\nSpiral exceed those of state-of-the-art algorithms currently used in popular\nDEM codes such as Yade, MercuryDPM, LIGGGHTS, PFC, and more, at only slightly\nhigher computational cost. Also, beyond DEM, we see potential applications in\nall numerical simulations that involve the 3D rotation of extended bodies.",
        "positive": "Radial distribution function for hard spheres in fractal dimensions: A\n  heuristic approximation: Analytic approximations for the radial distribution function, the structure\nfactor, and the equation of state of hard-core fluids in fractal dimension $d$\n($1 \\leq d \\leq 3$) are developed as heuristic interpolations from the\nknowledge of the exact and Percus-Yevick results for the hard-rod and\nhard-sphere fluids, respectively. In order to assess their value, such\napproximate results are compared with those of recent Monte Carlo simulations\nand numerical solutions of the Percus-Yevick equation for fractal dimension [M.\nHeinen et al., Phys. Rev. Lett. \\textbf{115}, 097801 (2015)], a good agreement\nbeing observed."
    },
    {
        "anchor": "Orientational properties of nematic disclinations: Topological defects play a pivotal role in the physics of liquid crystals and\nrepresent one of the most prominent and well studied aspects of mesophases.\nWhile in two-dimensional nematics, disclinations are traditionally treated as\npoint-like objects, recent experimental studies on active nematics have\nsuggested that half-strength disclinations might in fact possess a polar\nstructure. In this article, we provide a precise definition of polarity for\nhalf-strength nematic disclinations, we introduce a simple and robust method to\ncalculate this quantity from experimental and numerical data and we investigate\nhow the orientational properties of half-strength disclinations affect their\nrelaxational dynamics.",
        "positive": "Self-consistent field predictions for quenched spherical biocompatible\n  triblock copolymer micelles: We have used the Scheutjens-Fleer self-consistent field (SF-SCF) method to\npredict the self-assembly of triblock copolymers with a solvophilic middle\nblock and sufficiently long solvophobic outer blocks. We model copolymers\nconsisting of polyethylene oxide (PEO) as solvophilic block and\npoly(lactic-co-glycolic) acid (PLGA) or poly({\\ko}-caprolactone) (PCL) as\nsolvophobic block. These copolymers form structurally quenched spherical\nmicelles provided the solvophilic block is long enough. Predictions are\ncalibrated on experimental data for micelles composed of PCL-PEO-PCL and\nPLGA-PEO-PLGA triblock copolymers prepared via the nanoprecipitation method. We\nestablish effective interaction parameters that enable us to predict various\nmicelle properties such as the hydrodynamic size, the aggregation number and\nthe loading capacity of the micelles for hydrophobic species that are\nconsistent with experimental finding."
    },
    {
        "anchor": "Rotation of a submerged finite cylinder moving down a soft incline: A submerged finite cylinder moving under its own weight along a soft incline\nlifts off and slides at a steady velocity while also spinning. Here, we\nexperimentally quantify the steady spinning of the cylinder and show\ntheoretically that it is due to a combination of an elastohydrodynamic torque\ngenerated by flow in the variable gap, and the viscous friction on the edges of\nthe finite-length cylinder. The relative influence of the latter depends on the\naspect ratio of the cylinder as well as the deformability of the substrate,\nwhich we express in term of a single scaled compliance parameter. By varying\nthis compliance parameter, we show that our experimental results are consistent\nwith a transition from an edge-effect dominated regime for short cylinders to a\ngap-dominated elastohydrodynamic regime when the cylinder is very long.",
        "positive": "Nucleation of frictional sliding by coalescence of microslip: The onset of frictional motion is mediated by the dynamic propagation of a\nrupture front, analogous to a shear crack. The rupture front nucleates\nquasi-statically in a localized region of the frictional interface and slowly\nincreases in size. When it reaches a critical nucleation length it becomes\nunstable, propagates dynamically and eventually breaks the entire interface,\nleading to macroscopic sliding. The nucleation process is particularly\nimportant because it determines the stress level at which the frictional\ninterface fails, and therefore, the macroscopic friction strength. However, the\nmechanisms governing nucleation of frictional rupture fronts are still not well\nunderstood. Specifically, our knowledge of the nucleation process along a\nheterogeneous interface remains incomplete. Here, we study the nucleation of\nlocalized slip patches on linear slip-weakening interfaces with deterministic\nand stochastic heterogeneous friction properties. Using numerical simulations,\nwe analyze the process leading to a slip patch of critical size for systems\nwith varying correlation lengths of the local friction strength. Our\ndeterministic interface model reveals that the growth of the critical\nnucleation patch at interfaces with small correlation lengths is non smooth due\nto the coalescence of neighboring slip patches. Existing analytical solutions\ndo not account for this effect, which leads to an overestimation of global\ninterface strength. Conversely, when the correlation length is large, the\ngrowth of the slip patch is continuous and our simulations match the analytical\nsolution. Furthermore, nucleation by coalescence is also observed on stochastic\ninterfaces with small correlation length..."
    },
    {
        "anchor": "Bedforms in a turbulent stream.Part 2: Formation of ripples by primary\n  linear instability and of dunes by non-linear pattern coarsening: It is widely accepted that both ripples and dunes form in rivers by primary\nlinear instability, the wavelength of the former scaling on the grain size,\nthat of the latter being controled by the water depth. We revisit here this\nproblem, using the computation of the turbulent flow over a wavy bottom\nperformed in Part 1. The details of the different mechanisms controlling\nsediment transport are encoded into three quantities: the saturated flux, the\nsaturation length and the threshold shear stress. Theses quantities are\nmodelled in the case of erosion and momentum limited bed loads. This framework\nallows to give a clear picture of the instability in terms of dynamical\nmechanisms. The relation between the wavelength at which ripples form and the\nflux saturation length is quantitatively derived. Inverting the problem,\nexperimental data is used to determine the saturation length as a function of\ngrain size and shear velocity. Finally, using the systematic expansion of the\nflow field with respect to the corrugation amplitude, we discuss the non-linear\nselection of ripple aspect ratio. Investingating the effect of a free surface\non the linear instability, we show that the excitation of standing waves at the\nsurface has a stabilising effect, independently of the details of the flow and\nsediment transport models. Consequently, the shape of the dispersion relation\nis such that dunes can not result from a primary linear instability. We present\nthe results of field experiments performed in the natural sandy Leyre river,\nwhich evidence the formation of ripples by a linear instability and the\nformation of dunes by a non-linear pattern coarsening limited by the free\nsurface. We show that mega-dunes form when the sand bed presents\nheterogeneities such as a wide distribution of grain sizes.",
        "positive": "Structural Properties of Stiff Elastic Networks: Networks of elastic beams can deform either by stretching or bending of their\nmembers. The primary mode of deformation (bending or stretching) crucially\ndepends on the specific details of the network architecture. In order to shed\nlight on the relationship between microscopic geometry and macroscopic\nmechanics, we characterize the structural features of networks which deform\nuniformly, through the stretching of the beams only. We provide a convenient\nset of geometrical criteria to identify such networks, and derive the values of\ntheir effective elastic moduli. The analysis of these criteria elucidates the\nvariability of mechanical response of elastic networks. In particular, our\nstudy rationalizes the difference in mechanical behavior of cellular and fiber\nnetworks."
    },
    {
        "anchor": "Electro-osmotic properties of porous permeable films: Permeable porous coatings on a flat solid support significantly impact its\nelectrostatic and electrokinetic properties. Existing work has focused on\nsimplified cases, such as weakly charged and/or thick porous films, with\nlimited theoretical guidance. Here, we consider the general case of coatings of\nany given volume charge density and obtain analytic formulas for electrostatic\npotential profiles, valid for any film thickness and salt concentration. They\nallow us to calculate analytically the difference between potentials at solid\nsupport and at interface with an outer electrolyte, that is the key parameter\nascertaining the functionality of permeable coatings. Our analysis provides a\nframework for interpreting and predicting specific for porous films\nsuper-properties, from an enhanced ion absorption to a giant amplification of\nelectro-osmotic flows. The results are relevant for hydrogel and zeolite\ncoatings, porous carbon and ion-exchange resins, polyelectrolyte brushes, and\nmore.",
        "positive": "Vitrification, relaxation and free volume in glycerol-water binary\n  liquid mixture: Spin probe ESR studies: Glass transition and relaxation of the glycerol-water binary mixture system\nare studied over the glycerol concentration range of 5 - 85 mol% using the\nhighly sensitive technique of spin probe ESR. For the water rich mixture the\nglass transition, sensed by the spin probe, arises from the vitrified\nmesoscopic portion of the binary system. The concentration dependence of the\nglass transition temperature manifests a closely related molecular level\ncooperativity in the system. A drastic change in the mesoscopic structure of\nthe system at the critical concentration of 40 mol% is confirmed by an\nestimation of the spin probe effective volume in a temperature range where the\ntracer reorientation is strongly coupled to the system dynamics."
    },
    {
        "anchor": "Cold-burst method for nanoparticle formation with natural triglyceride\n  oils: Preparation of nanoemulsions of triglyceride oils in water usually requires\nhigh mechanical energy and sophisticated equipment. Recently, we showed that\nalpha-to-beta (viz. gel-to-crystal) phase transition, observed with most lipid\nsubstances (triglycerides, diglycerides, phospholipids, alkanes, etc.), may\ncause spontaneous disintegration of micro-particles of these lipids, dispersed\nin aqueous solutions of appropriate surfactants, into nanometer particles/drops\nusing a simple cooling/heating cycle of the lipid dispersion (Cholakova et al.\nACS Nano 14 (2020) 8594). In the current study we show that this \"cold-burst\nprocess\" is observed also with natural oils of high practical interest, incl.\ncoconut oil, palm kernel oil and cocoa butter. Mean drop diameters of ca. 50 to\n100 nm were achieved with some of the studied oils. From the results of\ndedicated model experiments we conclude that intensive nano-fragmentation is\nobserved when the following requirements are met: (1) The three phase contact\nangle at the air-water-solid lipid interface is below ca. 30 degrees; (2) The\nequilibrium surface tension of the surfactant solution is below ca. 30 mN/m and\nthe dynamic surface tension decreases rapidly. (3) The surfactant solution\ncontains non-spherical surfactant micelles. e.g. ellipsoidal micelles or bigger\nsupramolecular aggregates; (4) The three phase contact angle measured at the\ncontact line (frozen oil-melted oil-surfactant solution) is also relatively\nlow. The mechanism(s) of the particle bursting process is revealed and, on this\nbasis, the role of all these factors is clarified and discussed. We explain all\nmain effects observed experimentally and define guiding principles for\noptimization of the cold-burst process in various, practically relevant\nlipid-surfactant systems.",
        "positive": "The Thermodynamics of a Single Bead in a Vibrating Container: Statistics of the 1d dynamics of a single particle in a box of length L is\nstudied under different conditions of periodic excitation: vibrated container,\nor 1 wall moving periodically or two walls vibrating in opposite phases.\nTheoretical predictions for the mean typical speed <v> are derived using some\nRandom Phase Approximation (RPA) for small b/L ratio, as functions of the\namplitude b and frequency f of vibration and of the collision restitution\ncoefficient r=vout/vin. They are compared to numerical simulations. It is\nconcluded that RPA is valid for b/L>0.005, that long time memory, i.e. non\nergodicity, and/or resonance develop at large restitution coefficient r\n(r>0.95) and/or at large b/L, that <v> scales always as f, and scales as b\nexcept for large b/L values, i.e. b/L>0.02, and that the relative velocity\n<V>=[<v>/(bf)] is about 1 when r<0.4-0.5 . Relative standard deviation DV/V is\nfound to be approximately constant, i.e. DV/V is about 0.3 except when\nresonance occurs; in this case, memory effect and non ergodicity effects are\nobserved and become too important . Pacs # : 5.40 ; 45.70 ; 64 ; 83.70.Fn"
    },
    {
        "anchor": "Regulating Aggregation of Colloidal Particles in an Electro-Osmotic\n  Micropump: Unrestricted particle transport through microfluidic channels is of paramount\nimportance to a wide range of applications, including lab-on-a-chip devices. In\nthis article, we study using video microscopy the electro-osmotic aggregation\nof colloidal particles at the opening of a micrometer-sized silica channel in\npresence of a salt gradient. Particle aggregation eventually leads to clogging\nof the channel, which may be undone by a time-adjusted reversal of the applied\nelectric potential. We numerically model our system via the\nStokes-Poisson-Nernst-Planck equations in a geometry that approximates the real\nsample. This allows us to identify the transport processes induced by the\nelectric field and salt gradient and to provide evidence that a balance thereof\nleads to aggregation. We further demonstrate experimentally that a net flow of\ncolloids through the channel may be achieved by applying a square-waveform\nelectric potential with an appropriately tuned duty cycle. Our results serve to\nguide the design of microfluidic and nanofluidic pumps that allow for\ncontrolled particle transport and provide new insights for anti-fouling in\nultra-filtration.",
        "positive": "Monte Carlo simulation of particle size separation in evaporating\n  bi-dispersed colloidal droplets on hydrophilic substrates: Colloidal droplets are used in a variety of practical applications. Some of\nthese applications require particles of different sizes. These include medical\ndiagnostic methods, the creation of photonic crystals, the formation of\nsupraparticles, and the production of membranes for biotechnology. A series of\nearlier experiments had shown the possibility of particle separation near the\ncontact line, dependent upon their size. A mathematical model has been\ndeveloped to describe this process. Bi-dispersed colloidal droplets evaporating\non a hydrophilic substrate are taken into consideration. A particle monolayer\nis formed near the periphery of such droplets due to the small value of the\ncontact angle. The shape of the resulting deposit is associated with the coffee\nring effect. The model takes into account both particle diffusion and transfers\ncaused by capillary flow due to liquid evaporation. Monte Carlo simulations of\nsuch particle dynamics have been performed at several values of particle\nconcentration in the colloidal solution. The numerical results agree with the\nexperimental observations, in which small particles accumulate nearer to the\ncontact line than do the large particles. However, the particles do not\nactually reach the contact line, but accumulate at a small distance from it.\nThe reason for this is the surface tension acting on the particles in areas\nwhere the thickness of the liquid layer is comparable to the particle size.\nIndeed, the same mechanism affects the observed separation of the small and\nlarge particles."
    },
    {
        "anchor": "Atomic-scale origin of dynamic viscoelastic response and creep in\n  disordered solids: Viscoelasticity has been described since the time of Maxwell as an\ninterpolation of purely viscous and purely elastic response, but its\nmicroscopic atomic-level mechanism in solids has remained elusive. We studied\nthree model disordered solids: a random lattice, the bond-depleted fcc lattice,\nand the fcc lattice with vacancies. Within the harmonic approximation for\ncentral-force lattices, we applied sum-rules for viscoelastic response derived\non the basis of non-affine atomic motions. The latter motions are a direct\nresult of local structural disorder, and in particular, of the lack of\ninversion-symmetry in disordered lattices. By defining a suitable quantitative\nand general atomic-level measure of nonaffinity and inversion-symmetry, we show\nthat the viscoelastic responses of all three systems collapse onto a master\ncurve upon normalizing by the overall strength of inversion-symmetry breaking\nin each system. Close to the isostatic point for central-force lattices,\npower-law creep $G(t)\\sim t^{-1/2}$ emerges as a consequence of the interplay\nbetween soft vibrational modes and non-affine dynamics, and various analytical\nscalings, supported by numerical calculations, are predicted by the theory.",
        "positive": "Asymmetric electrolytes near structured dielectric interfaces: The ion distribution of electrolytes near interfaces with dielectric contrast\nhas important consequences for electrochemical processes and many other\napplications. To date, most studies of such systems have focused on\ngeometrically simple interfaces, for which dielectric effects are analytically\nsolvable or computationally tractable. However, all real surfaces display\nnontrivial structure at the nanoscale and have, in particular, nonuniform local\ncurvature. Using a recently developed, highly efficient computational method,\nwe investigate the effect of surface geometry on ion distribution and interface\npolarization. We consider an asymmetric 2:1 electrolyte bounded by a\nsinusoidally deformed solid surface. We demonstrate that even when the surface\nis neutral, the electrolyte acquires a nonuniform ion density profile near the\nsurface. This profile is asymmetric and leads to an effective charging of the\nsurface. We furthermore show that the induced charge is modulated by the local\ncurvature. The effective charge is opposite in sign to the multivalent ions and\nis larger in concave regions of the surface."
    },
    {
        "anchor": "Impact on floating thin elastic sheets: A mathematical model: We investigate impact of a sphere onto a floating elastic sheet and the\nresulting formation and evolution of wrinkles in the sheet. Following impact,\nwe observe a radially propagating wave, beyond which the sheet remains\napproximately planar but is decorated by a series of radial wrinkles whose\nwavelength grows in time. We develop a mathematical model to describe these\nphenomena by exploiting the asymptotic limit in which the bending stiffness is\nsmall compared to stresses in the sheet. The results of this analysis show\nthat, at a time $t$ after impact, the transverse wave is located at a radial\ndistance $r\\sim t^{1/2}$ from the impactor, in contrast to the classic $r\\sim\nt^{2/3}$ scaling observed for capillary--inertia ripples produced by dropping a\nstone into a pond. We describe the shape of this wave, starting from the\nsimplest case of a point impactor, but subsequently addressing a finite-radius\nspherical impactor, contrasting this case with the classic Wagner theory of\nimpact. We show also that the coarsening of wrinkles in the flat portion of the\nsheet is controlled by the inertia of the underlying liquid: short-wavelength,\nsmall-amplitude wrinkles form at early times since they accommodate the\ngeometrically-imposed compression without significantly displacing the\nunderlying liquid. As time progresses, the liquid accelerates and the wrinkles\ngrow larger and coarsen. We explain this coarsening quantitatively using\nnumerical simulations and scaling arguments, and we compare our predictions\nwith experimental data.",
        "positive": "Encapsulation of fragrances and oils by core-shell structures from\n  silica nanoparticles, surfactant and polymer: Effect of particle size: Oils and fragrances can be encapsulated by using composite shells of silica\nnanoparticles, polymer and surfactant (potassium oleate). The template for the\ncreation of the core-shell structure is a particle stabilized (Pickering)\nemulsion. The surfactant adsorbs on the nanoparticles and leads to their\nreversible hydrophobization and adsorption on the oil-water interface. The\nouter layer of the self-assembled shell represents a layer from crosslinked\npolymer. The procedure of encapsulation is simple and includes single\nhomogenization by ultrasound of the formulation that contains all ingredients\ntogether. The produced capsules have mean radius in the range between 2 and 11\nmicrons. By order of magnitude and trend, the capsule size follows the law of\nlimited coalescence with respect to the dependence on nanoparticle size and\nconcentration. The composite structure of the shells leads also to dependence\non the concentrations of added polymer and surfactant. The produced\nmicrocapsules are stable when rinsed with pure water of pH in the range 3 - 10.\nHowever, if dispersed in water of pH > 11, the microcapsules are destabilized\nand release their cargo, i.e., they are pH-responsive. Various fragrances and\noils, such as limonene, citronellol, benzyl acetate, and sunflower seed oil\nwere encapsulated. The developed methodology could find applications in any\nfield, in which reversible encapsulation of oily substances is needed."
    },
    {
        "anchor": "Temperature dependence of bend elastic constant in oblique helicoidal\n  cholesterics: Elastic moduli of liquid crystals, known as Frank constants, are of\nquintessential importance for understanding fundamental properties of these\nmaterials and for the design of their applications. Although there are many\nmethods to measure the Frank constants in the nematic phase, little is known\nabout the elastic constants of the chiral version of the nematic, the so-called\ncholesteric liquid crystal, since the helicoidal structure of the cholesteric\nrenders these methods inadequate. Here we present a technique to measure the\nbend modulus $K_{33}$ of cholesterics that is based on the electrically tunable\nreflection of light at an oblique helicoidal $Ch_{OH}$ cholesteric structure.\n$K_{33}$ is typically smaller than 0.6 pN, showing a non-monotonous temperature\ndependence with a slight increase near the transition to the twist-bend phase.\n$K_{33}$ depends strongly on the molecular composition. In particular, chiral\nmixtures that contain the flexible dimer 1'',7''-bis(4-cyanobiphenyl-4'-yl)\nheptane (CB7CB) and rod-like molecules such as pentylcyanobiphenyl (5CB) show a\n$K_{33}$ value that is 5 times smaller than $K_{33}$ of pure CB7CB or of\nmixtures of CB7CB with chiral dopants. Furthermore, $K_{33}$ in CB11CB doped\nwith a chiral agent is noticeably smaller than $K_{33}$ in a similarly doped\nCB7CB which is explained by the longer flexible link in CB11CB. The proposed\ntechnique allows a direct in-situ determination of how the molecular\ncomposition, molecular structure and molecular chirality affect the elastic\nproperties of chiral liquid crystals.",
        "positive": "Efficient equilibration of confined and free-standing films of highly\n  entangled polymer melts: Equilibration of polymer melts containing highly entangled long polymer\nchains in confinement or with free surfaces is a challenge for computer\nsimulations. We approach this problem by first studying polymer melts based on\nthe soft-sphere coarse-grained model confined between two walls with periodic\nboundary conditions in two directions parallel to the walls. Then we apply\nbackmapping to reinsert the microscopic details of the underlying bead-spring\nmodel. Tuning the strength of the wall potential, the monomer density of\nconfined polymer melts in equilibrium is kept at the bulk density even near the\nwalls. In a weak confining regime, we observe the same conformational\nproperties of chains as in the bulk melt showing that our confined polymer\nmelts have reached their equilibrated state. Our methodology provides an\nefficient way of equilibrating large polymer films with different thicknesses\nand is not confined to a specific underlying microscopic model. Switching off\nthe wall potential in the direction perpendicular to the walls, enables to\nstudy free-standing highly entangled polymer films or polymer films with one\nsupporting substrate."
    },
    {
        "anchor": "Phase-field modeling of isothermal quasi-incompressible multicomponent\n  liquids: In this paper general dynamic equations describing the time evolution of\nisothermal quasi-incompressible multicomponent liquids are derived in the\nframework of the classical Ginzburg-Landau theory of first order phase\ntransformations. Based on the fundamental {equations of continuum mechanics}, a\ngeneral convection-diffusion dynamics is set up first for compressible liquids.\nThe constitutive relations for the diffusion fluxes and the capillary stress\nare determined in the framework of gradient theories. {Next the general\ndefinition of incompressibility is given}, which is taken into account {in the\nderivation} by using the Lagrange multiplier method. To validate the theory,\nthe dynamic equations are solved numerically for the quaternary\nquasi-incompressible Cahn-Hilliard system. It is demonstrated that variable\ndensity (i) has no effect on equilibrium (in case of a suitably constructed\nfree energy functional), {and (ii) can} influence non-equilibrium pattern\nformation significantly.",
        "positive": "Intruder penetration into granular matter studied by Lock-in\n  Accelerometry: Understanding the penetration dynamics of intruders in granular beds is\nrelevant not only for fundamental physics, but also for geophysical processes\nand construction on sediments or granular soils in areas potentially affected\nby earthquakes. In this work, we use Lock-in accelerometry to study the\npenetration of intruders into quasi-2D granular matter fluidized by lateral\nshaking. We observed that there are two well-defined stages in the penetration\ndynamics as the intruder sinks into the granular material."
    },
    {
        "anchor": "Dynamics of a Brownian circle swimmer: Self-propelled particles move along circles rather than along a straight line\nwhen their driving force does not coincide with their propagation direction.\nExamples include confined bacteria and spermatozoa, catalytically driven\nnanorods, active, anisotropic colloidal particles and vibrated granulates.\nUsing a non-Hamiltonian rate theory and computer simulations, we study the\nmotion of a Brownian \"circle swimmer\" in a confining channel. A sliding mode\nclose to the wall leads to a huge acceleration as compared to the bulk motion,\nwhich can further be enhanced by an optimal effective torque-to-force ratio.",
        "positive": "Mechanochemical enzymes and protein machines as hydrodynamic force\n  dipoles: The active dimer model: Mechanochemically active enzymes change their shapes within every turnover\ncycle. Therefore, they induce circulating flows in the solvent around them and\nbehave as oscillating hydrodynamic force dipoles. Because of non-equilibrium\nfluctuating flows collectively generated by the enzymes, mixing in the solution\nand diffusion of passive particles within it are expected to get enhanced.\nHere, we investigate the intensity and statistical properties of such force\ndipoles in the minimal active dimer model of a mechanochemical enzyme. In the\nframework of this model, novel estimates for hydrodynamic collective effects in\nsolution and in lipid bilayers under rapid rotational diffusion are derived,\nand available experimental and computational data is examined."
    },
    {
        "anchor": "Structure and equation of state of interaction site models for\n  disc-shaped lamellar colloids: We apply RISM (Reference Interaction Site Model) and PRISM (polymer-RISM)\ntheories to calculate the site-site pair structure and the osmotic equation of\nstate of suspensions of circular or hexagonal platelets (lamellar colloids)\nover a range of ratios of the particle diameter over thickness. Despite the\nneglect of edge effects, the simpler PRISM theory yields results in good\nagreement with the more elaborate RISM calculations, provided the correct form\nfactor, characterizing the intramolecular structure of the platelets, is used.\nThe RISM equation of state is sensitive to the number of sites used to model\nthe platelets, but saturates when the hard spheres, associated with the\ninteraction sites, nearly touch; the limiting equation of state agrees\nreasonably well with available simulation data for all densities up to the\nisotropic-nematic transition. When properly scaled with the second virial\ncoefficient, the equations of state of platelets with different aspect ratios\nnearly collapse on a single master curve.",
        "positive": "Bridging the gap between molecular dynamics and hydrodynamics in\n  nanoscale Brownian motions: Through molecular dynamics simulations, we examined hydrodynamic behavior of\nthe Brownian motion of fullerene particles based on molecular interactions. The\nsolvation free energy and the velocity autocorrelation function (VACF) were\ncalculated by using the Lennard-Jones (LJ) and Weeks-Chandler-Andersen (WCA)\npotentials for the solute-solvent and solvent-solvent interactions and by\nchanging the size of the fullerene particles. We also measured the diffusion\nconstant of the fullerene particles and the shear viscosity of the host fluid,\nand then the hydrodynamic radius $a_\\mathrm{HD}$ was quantified from the\nStokes-Einstein relation. The $a_\\mathrm{HD}$ value exceeds that of the\ngyration radius of the fullerene when the solvation free energy exhibits\nlargely negative values using the LJ potential. In contrast, $a_\\mathrm{HD}$\nbecomes comparable to the size of bare fullerene, when the solvation free\nenergy is positive using the WCA potential. Furthermore, the VACF of the\nfullerene particles is directly comparable with the analytical expressions\nutilizing the Navier-Stokes equations both in incompressible and compressible\nforms. Hydrodynamic long-time tail $t^{-3/2}$ is demonstrated for timescales\nlonger than the kinematic time of the momentum diffusion over the particles'\nsize. However, the VACF in shorter timescales deviates from the hydrodynamic\ndescription, particularly for smaller fullerene particles and for the LJ\npotential. This occurs even though the compressible effect is considered when\ncharacterizing the decay of VACF around the sound propagation time scale over\nthe particles' size. These results indicate that the nanoscale Brownian motion\nis influenced by the solvation structure around the solute particles\noriginating from the molecular interaction."
    },
    {
        "anchor": "Dynamics of a simple model microswimmer in an anisotropic fluid:\n  implications for alignment behavior and active transport in a nematic liquid\n  crystal: Several recent experiments investigate the orientational and transport\nbehavior of self-driven bacteria and colloidal particles in nematic liquid\ncrystals. Correspondingly, we study theoretically the dynamics of a minimal\nmodel microswimmer in a uniaxially anisotropic fluid. As a first step, the\nhydrodynamic Green's function providing the resulting fluid flow in response to\na localized force acting on the anisotropic fluid is derived analytically. On\nthis basis, the behavior of both puller- and pusher-type microswimmers in the\nanisotropic fluid is analyzed. Depending on the propulsion mechanism and the\nrelative magnitude of different involved viscosities, we find alignment of the\nswimmers parallel or perpendicular to the anisotropy axis. Particularly, also\nan oblique alignment is identified under certain circumstances. The observed\nswimmer reorientation results from the hydrodynamic coupling between the\nself-induced fluid flow and the anisotropy of the surrounding fluid, which\ndistorts the self-generated flow field. We support parts of our results by a\nsimplified linear stability analysis. Our theoretical predictions are in\nqualitative agreement with recent experimental observations on swimming\nbacteria in nematic liquid crystals. They support the objective of utilizing\nthe, possibly switchable, anisotropy of a host fluid to guide individual\nmicroswimmers and active particles along a requested path, enabling controlled\nactive transport.",
        "positive": "Geometry and the onset of rigidity in a disordered network: Disordered spring networks that are undercoordinated may abruptly rigidify\nwhen sufficient strain is applied. Since the deformation in response to applied\nstrain does not change the generic quantifiers of network architecture - the\nnumber of nodes and the number of bonds between them - this rigidity transition\nmust have a geometric origin. Naive, degree-of-freedom based mechanical\nanalyses such as the Maxwell-Calladine count or the pebble game algorithm\noverlook such geometric rigidity transitions and offer no means of predicting\nor characterizing them. We apply tools that were developed for the topological\nanalysis of zero modes and states of self-stress on regular lattices to\ntwo-dimensional random spring networks, and demonstrate that the onset of\nrigidity, at a finite simple shear strain $\\gamma^\\star$, coincides with the\nappearance of a single state of self stress, accompanied by a single floppy\nmode. The process conserves the topologically invariant difference between the\nnumber of zero modes and the number of states of self stress, but imparts a\nfinite shear modulus to the spring network. Beyond the critical shear, we\nconfirm previously reported critical scaling of the modulus. In the\nsub-critical regime, a singular value decomposition of the network's\ncompatibility matrix foreshadows the onset of rigidity by way of a continuously\nvanishing singular value corresponding to nascent state of self stress."
    },
    {
        "anchor": "Hole-Burning Diffusion Measurements in High Magnetic Field Gradients: We describe methods for the measurement of translational diffusion in very\nlarge static magnetic field gradients by NMR. The techniques use a\n\"hole-burning\" sequence that, with the use of fringe field gradients of 42 T/m,\ncan image diffusion along one dimension on a submicron scale. Two varieties of\nthis method are demonstrated, including a particularly efficient mode called\nthe \"hole-comb,\" in which multiple diffusion times comprising an entire\ndiffusive evolution can be measured within the span of a single detected slice.\nThe advantages and disadvantages of these methods are discussed, as well as\ntheir potential for addressing non-Fickian diffusion, diffusion in restricted\nmedia, and spatially inhomogeneous diffusion.",
        "positive": "Energy polydisperse 2d Lennard-Jones fluid in presence of flow field: The behavior of energy polydisperse $2d$ Lennard-Jones fluid (in thin-film\ngeometry) is studied subjected to linear flow field using molecular dynamics\nsimulations. By considering neutral and selective substrates we systematically\nexplore the effect of flow field on particle ordering as well as response of\nthe system. It is shown that particle density profile, spatial organization as\nwell as local particle identity ordering in the film are affected. Furthermore,\nwe observe flow field induced melting associated with a decrease of effective\ninteraction parameter, $\\left< \\epsilon_i^{\\rm eff} \\right>$, which\ncharacterizes local neighborhood identity ordering. In terms of macroscopic\nresponse, the systems show both shear-thinning and shear-thickening behaviors,\nand shear-thinning exponent decreases with increasing temperature and\neventually attains Netwonian fluid-like behavior at sufficiently high\ntemperature. It is found that the qualitative behaviour of one component\nLJ-fluid and energy polydisperse fluid with neutral substrates are similar in\nmany respects, while the one with selective substrate shows differences. In the\ncase of energy polydisperse system, the effect of having different substrate\ntypes is significantly manifested in the density profile near the interface,\n$\\left< \\epsilon_i^{\\rm eff} \\right>$, and in the viscosity. We have shown\nthat, unlike one component fluid, it is possible to tune the macroscopic\nresponse by tuning substrate-fluid interaction in energy polydisperse fluids."
    },
    {
        "anchor": "A theory of ordering of elongated and curved proteins on membranes\n  driven by density and curvature: Cell membranes interact with a myriad of curvature-active proteins that\ncontrol membrane morphology and are responsible for mechanosensation and\nmechanotransduction. Some of these proteins, such as those containing BAR\ndomains, are curved and elongated, and hence may adopt different states of\norientational order, from isotropic to maximize entropy to nematic as a result\nof crowding or to adapt to the curvature of the underlying membrane. Here,\nextending the work of [Nascimento et. al, Phys. Rev. E, 2017, 96, 022704], we\ndevelop a mean-field density functional theory to predict the orientational\norder and evaluate the free-energy of ensembles of elongated and curved objects\non curved membranes. This theory depends on the microscopic properties of the\nparticles and explains how a density-dependent isotropic-to-nematic transition\nis modified by anisotropic curvature. We also examine the coexistence of\nisotropic and nematic phases. This theory lays the ground to understand the\ninterplay between membrane reshaping by BAR proteins and molecular order,\nexamined in [Le Roux et. al, Submitted, 2020].",
        "positive": "Drift instability in the motion of a fluid droplet with a chemically\n  reactive surface driven by Marangoni flow: We theoretically derive the amplitude equations for a self-propelled droplet\ndriven by Marangoni flow. As advective flow driven by surface tension gradient\nis enhanced, the stationary state becomes unstable and the droplet starts to\nmove. The velocity of the droplet is determined from a cubic nonlinear term in\nthe amplitude equations. The obtained critical point and the characteristic\nvelocity are well supported by numerical simulations."
    },
    {
        "anchor": "How to determine local elastic properties of lipid bilayer membranes\n  from atomic-force-microscope measurements: A theoretical analysis: Measurements with an atomic force microscope (AFM) offer a direct way to\nprobe elastic properties of lipid bilayer membranes locally: provided the\nunderlying stress-strain relation is known, material parameters such as surface\ntension or bending rigidity may be deduced. In a recent experiment a\npore-spanning membrane was poked with an AFM tip, yielding a linear behavior of\nthe force-indentation curves. A theoretical model for this case is presented\nhere which describes these curves in the framework of Helfrich theory. The\nlinear behavior of the measurements is reproduced if one neglects the influence\nof adhesion between tip and membrane. Including it via an adhesion balance\nchanges the situation significantly: force-distance curves cease to be linear,\nhysteresis and nonzero detachment forces can show up. The characteristics of\nthis rich scenario are discussed in detail in this article.",
        "positive": "Dynamics and complex formation in charged and uncharged Ficoll70\n  solutions: We apply pulsed-field-gradient NMR (PFG NMR) technique to measure the\ntranslational diffusion for both uncharged and charged polysaccharide\n(Ficoll70) in water. Analysis of the data indicate that NMR signal attenuation\nabove a certain packing fraction can be adequately fitted with a bi-exponential\nfunction. The self-diffusion measurements show also that the Ficoll70, an\noften-used compact, spherical polysucrose molecule, is itself non-ideal,\nexhibiting signs of both softness and attractive interactions in the form of a\nstable suspension consisting of monomers and clusters. Further, we can quantify\nthe fraction of monomer and cluster. This work strengthens the picture of the\nexistence of a bound water layer within and around a porous Ficoll70 particle."
    },
    {
        "anchor": "Membrane penetration and trapping of an active particle: The interaction between nano- or micro-sized particles and cell membranes is\nof crucial importance in many biological and biomedical applications such as\ndrug and gene delivery to cells and tissues. During their cellular uptake, the\nparticles can pass through cell membranes via passive endocytosis or by active\npenetration to reach a target cellular compartment or organelle. In this\nmanuscript, we develop a simple model to describe the interaction of a\nself-driven spherical particle (moving through an effective constant active\nforce) with a minimal membrane system, allowing for both penetration and\ntrapping. We numerically calculate the state diagram of this system, the\nmembrane shape, and its dynamics. In this context, we show that the active\nparticle may either get trapped near the membrane or penetrates through it,\nwhere the membrane can either be permanently destroyed or recover its initial\nshape by self-healing. Additionally, we systematically derive a continuum\ndescription allowing to accurately predict most of our results analytically.\nThis analytical theory helps identifying the generic aspects of our model,\nsuggesting that most of its ingredients should apply to a broad range of\nmembranes, from simple model systems composed of magnetic microparticles to\nlipid bilayers. Our results might be useful to predict mechanical properties of\nsynthetic minimal membranes.",
        "positive": "Cytoskeleton confinement of red blood cell membrane fluctuations: We analyze both the static and dynamic fluctuation spectrum of the red-blood\ncell in a unified manner, using a simple model of the composite membrane. In\nthis model, the two-dimensional spectrin network that forms the cytoskeleton is\ntreated as a rigid shell which is located at some constant average separation\nfrom the lipid bilayer. The cytoskeleton thereby confines both the static and\ndynamic fluctuations of the lipid bilayer. The predictions of the model account\nfor the wavevector and frequency dependence of the experimental data. The\nobserved amplitude of the thermal fluctuations is related to effects of\nATP-driven fluctuations."
    },
    {
        "anchor": "The crystallization of asymmetric patchy models for globular proteins in\n  solution: Asymmetric patchy particle models have recently been shown to describe the\ncrystallization of small globular proteins with near quantitative accuracy.\nHere, we investigate how asymmetry in patch geometry and bond energy generally\nimpact the phase diagram and nucleation dynamics of this family of soft matter\nmodels. We find the role of the geometry asymmetry to be weak, but the energy\nasymmetry to markedly interfere with the crystallization thermodynamics and\nkinetics. These results provide a rationale for the success and occasional\nfailure of George and Wilson's proposal for protein crystallization conditions\nas well as physical guidance for developing more effective protein\ncrystallization strategies.",
        "positive": "Demixing in a single-peak distributed polydisperse mixture of hard\n  spheres: An analytic derivation of the spinodal of a polydisperse mixture is\npresented. It holds for fluids whose excess free energy can be accurately\ndescribed by a function of a few moments of the size distribution. It is shown\nthat one such mixture of hard spheres in the Percus-Yevick approximation never\ndemixes, despite its size distribution. In the\nBoublik-Mansoori-Carnahan-Starling-Leland approximation, though, it demixes for\na sufficiently wide log-normal size distribution. The importance of this result\nis twofold: first, this distribution is unimodal, and yet it phase separates;\nand second, log-normal size distributions appear in many experimental contexts.\nThe same phenomenon is shown to occur for the fluid of parallel hard cubes."
    },
    {
        "anchor": "Monomer dynamics of a wormlike chain: We derive the stochastic equations of motion for a tracer that is tightly\nattached to a semiflexible polymer and confined or agitated by an externally\ncontrolled potential. The generalised Langevin equation, the power spectrum,\nand the mean-square displacement for the tracer dynamics are explicitly\nconstructed from the microscopic equations of motion for a weakly bending\nwormlike chain by a systematic coarse-graining procedure. Our accurate\nanalytical expressions should provide a convenient starting point for further\ntheoretical developments and for the analysis of various single-molecule\nexperiments and of protein shape fluctuations.",
        "positive": "Foams in a rotating drum: A nearly two-dimensionnal foam is generated inside a Hele-Shaw cell\nhalf-filled with a surfactant solution. The cell is then placed vertically on a\ntumbler so that it rotates around its center with the cell angular velocity as\nthe control parameter. During the foam rotation the liquid fraction increases\nand the foam/liquid interface deforms. The shear velocity profiles generated\ninside the foam are studied along two representative lines. The foam\nrheological properties are obtained using statistical tools and allow us to\ndetermine the foam effective viscosity. A semiempirical model is proposed for\nthese velocity profiles, emphasizing the significance of the viscous\ndissipations between the bubbles and with the cell walls."
    },
    {
        "anchor": "Molecular mode-coupling theory for supercooled liquids: Application to\n  water: We present mode-coupling equations for the description of the slow dynamics\nobserved in supercooled molecular liquids close to the glass transition. The\nmode-coupling theory (MCT) originally formulated to study the slow relaxation\nin simple atomic liquids, and then extended to the analysis of liquids composed\nby linear molecules, is here generalized to systems of arbitrarily shaped,\nrigid molecules. We compare the predictions of the theory for the $q$-vector\ndependence of the molecular nonergodicity parameters, calculated by solving\nnumerically the molecular MCT equations in two different approximation schemes,\nwith ``exact'' results calculated from a molecular dynamics simulation of\nsupercooled water. The agreement between theory and simulation data supports\nthe view that MCT succeeds in describing the dynamics of supercooled molecular\nliquids, even for network forming ones.",
        "positive": "Randomly charged polymers in porous environment: We study the conformational properties of charged polymers in a solvent in\nthe presence of structural obstacles correlated according to a power law $\\sim\nx^{-a}$. We work within the continuous representation of a model of linear\nchain considered as a random sequence of charges $q_i=\\pm q_0$. Such a model\ncaptures the properties of polyampholytes -- heteropolymers comprising both\npositively and negatively charged monomers. We apply the direct polymer\nrenormalization scheme and analyze the scaling behavior of charged polymers up\nto the first order of an $\\epsilon=6-d$, $\\delta=4-a$-expansion."
    },
    {
        "anchor": "Unjamming of Granular Packings due to Local Perturbations: Stability and\n  Decay of Displacements: We study the mechanical response generated by local deformations in jammed\npackings of rigid disks. Based on discrete element simulations we determine the\ncritical force of the local perturbation that is needed to break the mechanical\nequilibrium and examine the generated displacement field. Displacements decay\nas a power law of the distance from the perturbation point. The decay exponent\nand the critical force exhibit nontrivial dependence on the friction: Both\nquantities are nonmonotonic and have a sharp maximum at the friction\ncoefficient 0.1. We find that the mechanical response properties are closely\nrelated to the problem of force-indeterminacy where similar nonmonotonic\nbehavior was observed previously. We establish direct connection between the\ncritical force and the ensemble of static force networks.",
        "positive": "Modulation of elasticity and interactions in charged lipid\n  multibilayers: monovalent salt solutions: We have studied the electrostatic screening effect of NaCl solutions on the\ninteractions between anionic lipid bilayers in the fluid lamellar phase using a\nPoisson-Boltzmann based mean-field approach with constant charge and constant\npotential limiting charge regulation boundary conditions. The full DLVO\npotential, including the electrostatic, hydration and van der Waals\ninteractions, was coupled to thermal bending fluctuations of the membranes via\na variational Gaussian Ansatz. This allowed us to analyze the coupling between\nthe osmotic pressure and the fluctuation amplitudes and compare them both\nsimultaneously with the measured dependence on the bilayer separation,\ndetermined by the small-angle X-ray scattering experiments. High-structural\nresolution analysis of the scattering data revealed no significant changes of\nmembrane structure as a function of salt concentration. Parsimonious\ndescription of our results is consistent with the constant charge limit of the\ngeneral charge regulation phenomenology, with fully dissociated lipid charge\ngroups, together with a four-fold reduction of the membranes' bending rigidity\nupon increasing NaCl concentration."
    },
    {
        "anchor": "A General Structural Order Parameter for the Amorphous Solidification of\n  a Supercooled Liquid: The persistent problem posed by the glass transition is to develop a general\natomic level description of a solidification process that is not associated\nwith any change in the symmetry of the atomic structure. The answer proposed in\nthis paper is t measure a configuration's capacity to restrain the motion of\nthe constituent atoms. Here we show that the instantaneous normal modes can be\nused to define a measure of atomic restraint that accounts for the difference\nbetween fragile and strong liquids and the collective length scale of the\nsupercooled liquid. These results represent a significant simplification of the\ndescription of amorphous solidification and provide a powerful systematic\ntreatment of the influence of microscopic factors on the formation of the\namorphous solid.",
        "positive": "A basic swimmer at low Reynolds number: Swimming and pumping at low Reynolds numbers are subject to the \"Scallop\ntheorem\", which states that there will be no net fluid flow for time reversible\nmotions. Living organisms such as bacteria and cells are subject to this\nconstraint, and so are existing and future artificial \"nano-bots\" or\nmicrofluidic pumps. We study a very simple mechanism to induce fluid pumping,\nbased on the forced motion of three colloidal beads through a cycle that breaks\ntime-reversal symmetry. Optical tweezers are used to vary the inter-bead\ndistance. This model is inspired by a strut-based theoretical swimmer proposed\nby Najafi and Golestanian [Phys.Rev. E, 69, 062901, 2004], but in this work the\nrelative softness of the optical trapping potential introduces a new control\nparameter. We show that this system is able to generate flow in a controlled\nfashion, characterizing the model experimentally and numerically."
    },
    {
        "anchor": "Effective non-additive pair potential for lock-and-key interacting\n  particles: the role of the limited valence: Theoretical studies of self-assembly processes and condensed phases in\ncolloidal systems are often based on effective inter-particle potentials. Here\nwe show that developing an effective potential for particles interacting with a\nlimited number of ``lock-and-key'' selective bonds (due to the specificity of\nbio-molecular interactions) requires -- beside the non-sphericity of the\npotential -- a (many body) constraint that prevent multiple bonding on the same\nsite. We show the importance of retaining both valence and bond-selectivity by\ndeveloping, as a case study, a simple effective potential describing the\ninteraction between colloidal particles coated by four single-strand DNA\nchains.",
        "positive": "Relation between the grafting density of liquid crystal macromolecule\n  and the symmetry of self-assembled bulk phase: coarse-grained molecular\n  dynamics study: I consider a generic coarse-grained model suitable for the study of bulk\nself-assembly of liquid crystal (LC) macromolecules. The cases include LC\ndendrimers, gold nanoparticles modified by polymer chains with terminating LC\ngroups and others. The study is focused on the relation between a number of\ngrafted chains, $N_{\\rm ch}$, and the symmetry of the self-assembled bulk\nphases. Simple space-filling arguments are used first to estimate stability\nintervals for a rod-like, disc-like and spherulitic conformations in terms of\n$N_{\\rm ch}$. These are followed by coarse-grained molecular dynamics\nsimulations for both spontaneous and aided self-assembly of LC macromolecules\ninto bulk phases. In spontaneous self-assembly runs, essential coexistence of\nrod-like and disc-like conformations is observed (via analysis of the\nhistograms for the molecular asphericity) in a broad interval of $N_{\\rm ch}$,\nwhich prevents the formation of defect-free structures. The use of uniaxial and\nplanar aiding fields is found to improve self-assembly into monodomain phases\nby promoting conformations of respective symmetry. Strong shape-phase relation,\nobserved experimentally, is also indicated by the simulations by the\ncoincidence of the stability intervals for the respective conformations with\nthose for the bulk phases."
    },
    {
        "anchor": "Chirality in Liquid Crystals: from Microscopic Origins to Macroscopic\n  Structure: Molecular chirality leads to a wonderful variety of equilibrium structures,\nfrom the simple cholesteric phase to the twist-grain-boundary phases, and it is\nresponsible for interesting and technologically important materials like\nferroelectric liquid crystals. This paper will review some recent advances in\nour understanding of the connection between the chiral geometry of individual\nmolecules and the important phenomenological parameters that determine\nmacroscopic chiral structure. It will then consider chiral structure in\ncolumnar systems and propose a new equilibrium phase consisting of a regular\nlattice of twisted ropes.",
        "positive": "Active beating of a reconstituted synthetic minimal axoneme: Propelling microorganisms through fluids and moving fluids along cellular\nsurfaces are essential biological functions accomplished by long, thin\nstructures called motile cilia and flagella, whose regular, oscillatory beating\nbreaks the time-reversal symmetry required for transport. Although top-down\nexperimental approaches and theoretical models have allowed us to broadly\ncharacterize such organelles and propose mechanisms underlying their complex\ndynamics, constructing minimal systems capable of mimicking ciliary beating and\nidentifying the role of each component remains a challenge. Here we report the\nbottom-up assembly of a minimal synthetic axoneme, which we call a synthoneme,\nusing biological building blocks from natural organisms, namely pairs of\nmicrotubules and cooperatively associated axonemal dynein motors. We show that\nupon provision of energy by ATP, microtubules undergo rhythmic bending by\ncyclic association-dissociation of dyneins. Our simple and unique beating\nminimal synthoneme represents a self-organized nanoscale biomolecular machine\nthat can also help understand the mechanisms underlying ciliary beating."
    },
    {
        "anchor": "Fracture energy of gels: To clarify effects of crack speed and cross-link density on fracture energy\nof acrylamide gels, we evaluated the roughness of the fracture surface and\nmeasured the fracture energy taking into account the roughness. The fracture\nenergy increases linearly with crack speed $V$ in a fast crack speed region,\nand the increasing rate of fracture energy with $V$ decreases with increasing\ncross link density in the gels. In a slow crack speed region the fracture\nenergy depends on crack speed more strongly than in the fast crack speed\nregion. This indicates that a qualitative change exists in fracture process of\nthe gels.",
        "positive": "Theory of cylindrical dense packings of disks: We have previously explored cylindrical packings of disks and their relation\nto sphere packings. Here we extend the analytical treatment of disk packings,\nanalysing the rules for phyllotactic indices of related structures and the\nvariation of the density for line-slip structures, close to the symmetric ones.\nWe show that rhombic structures, which are of a lower density, are always\nunstable i.e. can be increased in density by small perturbations"
    },
    {
        "anchor": "Spatial Dimensionality Dependence of Heterogeneity, Breakdown of the\n  Stokes-Einstein Relation and Fragility of a Model Glass-Forming Liquid: We investigate the heterogeneity of dynamics, the breakdown of the\nStokes-Einstein relation and fragility in a model glass forming liquid, a\nbinary mixture of soft spheres with a harmonic interaction potential, for\nspatial dimensions from 3 to 8. Dynamical heterogeneity is quantified through\nthe dynamical susceptibility $\\chi_4$, and the non-Gaussian parameter\n$\\alpha_2$. We find that the fragility, the degree of breakdown of the\nStokes-Einstein relation, as well as heterogeneity of dynamics, decrease with\nincreasing spatial dimensionality. We briefly describe the dependence of\nfragility on density, and use it to resolve an apparent inconsistency with\nprevious results.",
        "positive": "Positive disclination in a thin elastic sheet with boundary: An isolated positive wedge disclination deforms an initially flat elastic\nsheet into a perfect cone when the sheet is of infinite extent and is\nelastically inextensible. The latter requires the elastic stretching strains to\nbe vanishingly small. In this paper, rigorous analytical and numerical results\nare obtained for the disclination induced deformed shape and stress field of a\nbounded F{\\\"o}ppl-von K{\\'a}rm{\\'a}n elastic sheet with finite extensibility,\nwhile emphasising the deviations from the perfect cone solution. In particular,\nthe Gaussian curvature field is no longer localised as a Dirac singularity at\nthe defect location whenever elastic extensibility is allowed and is\nnecessarily negative in large regions away from the defect. The stress field,\nsimilarly, has no Dirac singularity in the presence of elastic extensibility.\nHowever, with increasing Young's modulus of the sheet, while keeping the\nbending modulus and the domain size fixed, both of these fields tend to develop\na Dirac singularity. Noticeably, in this limiting behaviour, inextensibility\neludes the bounded elastic sheet due to persisting regions of non-trivial\nGaussian curvature away from the defect. Other results in the paper include\nstudying the effect of specific boundary conditions (free, simply supported, or\npartially clamped) on the Gaussian curvature field away from the defect and on\nthe buckling transition from the flat to a conical solution."
    },
    {
        "anchor": "Directed Self-Assembly of Polarizable Ellipsoids in an External Electric\n  Field: The interplay between shape anisotropy and directed long-range interactions\nenables the self-assembly of complex colloidal structures. As a recent\nhighlight, ellipsoidal particles polarized in an external electric field were\nobserved to associate into well-defined tubular structures. In this study, we\ninvestigate systematically such directed self-assembly using Monte Carlo\nsimulations of a two-point-charge model of polarizable prolate ellipsoids. In\nspite of its simplicity and computational efficiency, we demonstrate that the\nmodel is capable of capturing the complex structures observed in experiments on\nellipsoidal colloids at low volume fractions. We show that, at sufficiently\nhigh electric field strength, the anisotropy in shape and electrostatic\ninteractions causes a transition from 3-dimensional crystal structures observed\nat low aspect ratios to 2-dimensional sheets and tubes at higher aspect ratios.\nOur work thus illustrates the rich self-assembly behavior accessible when\nexploiting the interplay between competing long- and short-range anisotropic\ninteractions in colloidal systems.",
        "positive": "Kinetics of Surfactant Micellization: a Free Energy Approach: We present a new theoretical approach to the kinetics of micelle formation in\nsurfactant solutions, in which the various stages of aggregation are treated as\nconstrained paths on a single free-energy landscape. Three stages of\nwell-separated time scales are distinguished. The first and longest stage\ninvolves homogeneous nucleation of micelles, for which we derive the size of\nthe critical nuclei, their concentration, and the nucleation rate.\nSubsequently, a much faster growth stage takes place, which is found to be\ndiffusion-limited for surfactant concentrations slightly above the critical\nmicellar concentration ({\\it cmc}), and either diffusion-limited or kinetically\nlimited for higher concentrations. The time evolution of the growth is derived\nfor both cases. At the end of the growth stage the micelle size may be either\nlarger or smaller than its equilibrium value, depending on concentration. A\nfinal stage of equilibration follows, during which the micelles relax to their\nequilibrium size through fission or fusion. Both cases of fixed surfactant\nconcentration (closed system) and contact with a reservoir of surfactant\nmonomers (open system) are addressed and found to exhibit very different\nkinetics. In particular, we find that micelle formation in an open system\nshould be kinetically suppressed over macroscopic times and involve two stages\nof micelle nucleation rather than one."
    },
    {
        "anchor": "Isostaticity and Mechanical Response of Two-Dimensional Granular Piles: We numerically study the static structure and the mechanical response of\ntwo-dimensional granular piles. The piles consist of polydisperse disks with\nand without friction. Special attention is paid for the rigid grain limit by\nexamining the systems with various disk elasticities. It is shown that the\nstatic pile structure of frictionless disks becomes isostatic in the rigid\nlimit, while the isostaticity of frictional pile depends on the pile forming\nprocedure, but in the case of the infinite friction is effective, the structure\nbecomes very close to isostatic in the rigid limit. The mechanical response of\nthe piles are studied by infinitesimally displacing one of the disks at the\nbottom. It is shown that the total amount of the displacement in the pile\ncaused by the perturbation diverges in the case of frictionless pile as it\nbecomes isostatic, while the response remains finite for the frictional pile.\nIn the frictionless isostatic pile, the displacement response in each sample\nbehaves rather complicated way, but its average shows wave like propagation.",
        "positive": "Critical Unmixing of Polymer Solutions: We present Monte Carlo simulations of semidilute solutions of long\nself-attracting chain polymers near their Ising type critical point. The\npolymers are modeled as monodisperse self-avoiding walks on the simple cubic\nlattice with attraction between non-bonded nearest neighbors. Chain lengths are\nup to N=2048, system sizes are up to $2^{21}$ lattice sites and $2.8\\times\n10^5$ monomers. These simulations used the recently introduced pruned-enriched\nRosenbluth method which proved extremely efficient, together with a histogram\nmethod for estimating finite size corrections. Our most clear result is that\nchains at the critical point are Gaussian for large $N$, having end-to-end\ndistances $R\\sim\\sqrt{N}$. Also the distance $T_\\Theta-T_c(N)$ (where $T_\\Theta\n= \\lim_{N\\to\\infty} T_c(N)$) scales with the mean field exponent, $T_\\Theta\n-T_c(N)\\sim 1/\\sqrt{N}$. The critical density seems to scale with a non-trivial\nexponent similar to that observed in experiments. But we argue that this is due\nto large logarithmic corrections. These corrections are similar to the very\nlarge corrections to scaling seen in recent analyses of $\\Theta$-polymers, and\nqualitatively predicted by the field theoretic renormalization group. The only\nserious deviation from this simple global picture concerns the N-dependence of\nthe order parameter amplitudes which disagrees with a minimalistic ansatz of de\nGennes. But this might be due to problems with finite size scaling. We find\nthat the finite size dependence of the density of states $P(E,n)$ (where $E$ is\nthe total energy and $n$ is the number of chains) is slightly but significantly\ndifferent from that proposed recently by several authors."
    },
    {
        "anchor": "Relaxation in the glass-former acetyl salicylic acid studied by deuteron\n  magnetic resonance and dielectric spectroscopy: Supercooled liquid and glassy acetyl salicylic acid was studied using\ndielectric spectroscopy and deuteron relaxometry in a wide temperature range.\nThe supercooled liquid is characterized by major deviations from thermally\nactivated behavior. In the glass the secondary relaxation exhibits the typical\nfeatures of a Johari-Goldstein process. Via measurements of spin-lattice\nrelaxation times the selectively deuterated methyl group was used as a\nsensitive probe of its local environments. There is a large difference in the\nmean activation energy in the glass with respect to that in crystalline acetyl\nsalicylic acid. This can be understood by taking into account the broad energy\nbarrier distribution in the glass.",
        "positive": "Ab initio theory and modeling of water: Water is of the utmost importance for life and technology. However, a\ngenuinely predictive ab initio model of water has eluded scientists. We\ndemonstrate that a fully ab initio approach, relying on the strongly\nconstrained and appropriately normed (SCAN) density functional, provides such a\ndescription of water. SCAN accurately describes the balance among covalent\nbonds, hydrogen bonds, and van der Waals interactions that dictates the\nstructure and dynamics of liquid water. Notably, SCAN captures the density\ndifference between water and ice I{\\it h} at ambient conditions, as well as\nmany important structural, electronic, and dynamic properties of liquid water.\nThese successful predictions of the versatile SCAN functional open the gates to\nstudy complex processes in aqueous phase chemistry and the interactions of\nwater with other materials in an efficient, accurate, and predictive, ab initio\nmanner."
    },
    {
        "anchor": "Infrared Imaging of the Nanometer-Thick Accumulation Layer in Organic\n  Field-Effect Transistors: We report on infrared (IR) spectro-microscopy of the electronic excitations\nin nanometer-thick accumulation layers in FET devices based on\npoly(3-hexylthiophene). IR data allows us to explore the charge injection\nlandscape and uncovers the critical role of the gate insulator in defining\nrelevant length scales. This work demonstrates the unique potential of IR\nspectroscopy for the investigation of physical phenomena at the nanoscale\noccurring at the semiconductor-insulator interface in FET devices.",
        "positive": "Stress response inside perturbed particle assemblies: The effect of structural disorder on the stress response inside three\ndimensional particle assemblies is studied using computer simulations of\nfrictionless sphere packings. Upon applying a localised, perturbative force\nwithin the packings, the resulting {\\it Green's} function response is mapped\ninside the different assemblies, thus providing an explicit view as to how the\nimposed perturbation is transmitted through the packing. In weakly disordered\narrays, the resulting transmission of forces is of the double-peak variety, but\nwith peak widths scaling linearly with distance from the source of the\nperturbation. This behaviour is consistent with an anisotropic elasticity\nresponse profile. Increasing the disorder distorts the response function until\na single-peak response is obtained for fully disordered packings consistent\nwith an isotropic description."
    },
    {
        "anchor": "Fast Evaporation Enabled Ultrathin Polymeric Coatings on Nanoporous\n  Substrates for Highly Permeable Membranes: Membranes derived from ultrathin polymeric films are promising to meet fast\nseparations, but currently available approaches to produce polymer films with\ngreatly reduced thicknesses on porous supports still faces challenges. Here,\ndefect-free ultrathin polymer covering films (UPCFs) are realized by a facile\ngeneral approach of rapid solvent evaporation. By fast evaporating dilute\npolymer solutions, we realize ultrathin coating (~30 nm) of porous substrates\nexclusively on the top surface, forming UPCFs with a block copolymer of\npolystyrene-block-poly(2-vinyl pyridine) at room temperature or a homopolymer\nof poly(vinyl alcohol) (PVA) at elevated temperatures. With subsequent\nselective swelling to the block copolymer and crosslinking to PVA, the\nresulting bi-layered composite structures serve as highly permeable membranes\ndelivering ~2-10 times higher permeability in ultrafiltration and pervaporation\napplications than state-of-the-art separation membranes with similar rejections\nand selectivities. This work opens up a new, facile avenue for the controllable\nfabrication of ultrathin coatings on porous substrates, which shows great\npotentials in membrane-based separations and other areas.",
        "positive": "Stiffer alginate gels deposit more efficiently in microchannel flows: The behavior of crosslinking polymer solutions as they transition from\nliquid-like to solid-like material in flow determines success or failure in\nseveral applications, from 3D printing to oil recovery in the earth's\nsubsurface to a wide variety of biological flows. Dilute polymer solutions flow\neasily, while concentrated polymers or crosslinked polymer gels can clog pores,\nnozzles, or channels. We have recently uncovered and described a third regime\nof flow dynamics in polymers that occurs when crosslinking happens during flow:\nintermittent flows. In a model system of alginate and calcium meeting at a\nY-shaped junction in a microfluidic channel, a persistent and regular pattern\nof intermittent flow occurs when driven at a constant volume flow rate. At the\njunction, calcium crosslinks alginate to form an alginate gel, which\nsubsequently deposits on the channel wall. As gel continues to deposit, it\nobstructs the channel, causing the driving pressure to increase to maintain a\nconstant flow rate. At a critical pressure, corresponding to a critical shear\nstress, the fluid pulls the gel from the wall, removing the gel from the device\nand resulting in a clear channel. The gel deposit begins again, and the process\nthen repeats as long as flow continues. Chemical concentrations and flow rate\ncontrol both the frequency of ablation and the critical shear stress. In this\nwork, we provide an analytical framework to quantitatively describe the\nintermittent behavior as a result of diffusively driven deposition in a high\nPeclet number flow where convection dominates. Fitting the experimental data to\nthe model allows estimation of the deposition efficiency, or the fraction of\nflowing material that sticks to the channel walls. By correlating the results\nof the model with bulk rheology measurements, we find that deposition\nefficiency increases with the stiffness of the gel formed in flow."
    },
    {
        "anchor": "Entropic attraction of adhesion bonds toward cell boundaries: Adhesion bonds between membranes and surfaces are attracted to each other via\neffective interactions whose origin the entropy loss due to the reduction in\nthe amplitude of the membrane thermal fluctuations in the vicinity of the\nadhesion bonds. These fluctuation-induced interactions are also expected to\ndrive the adhesion bonds toward the rim of the cell, as well as toward the\nsurfaces of membrane inclusions. In this paper, we analyze the attraction of\nadhesion bonds to the cell inner and outer boundaries. Our analysis shows that\nthe probability distribution function of a single (diffusing) adhesion bond\ndecay algebraically with the distance from the boundaries. Upon increasing the\nconcentration of the adhesion bonds, the attraction to the boundaries becomes\nstrongly self-screened.",
        "positive": "A theory for the dynamics of glassy mixtures with particle size swaps: We present a theory for the dynamics of a binary mixture with particle size\nswaps. The theory is based on a factorization approximation similar to that\nemployed in the mode-coupling theory of glassy dynamics. The theory shows that,\nin accordance with physical intuition, particle size swaps open up an\nadditional channel for the relaxation of density fluctuations. Thus, allowing\nswaps speeds up the dynamics and moves the dynamic glass transition towards\nhigher densities and/or lower temperatures. We calculate an approximate dynamic\nglass transition phase diagram for an equimolar binary hard sphere mixture. We\nfind that in the presence of particle size swaps, with increasing ratio of the\nhard sphere diameters the dynamic glass transition line moves towards higher\nvolume fractions, up to the ratio of the diameters approximately equal to 1.2,\nand then saturates. We comment on the implications of our findings for the\ntheoretical description of the glass transition."
    },
    {
        "anchor": "Entropic rectification and current inversion in a pulsating channel: We show the existence of a resonant behavior of the current of Brownian\nparticles confined in a pulsating channel. The interplay between the periodic\noscillations of the shape of the channel and a force applied along its axis\nleads to an increase of the particle current as a function of the noise level.\nA regime of current inversion is also observed for particular values of the\noscillation frequency and the applied force. The model proposed to obtain these\nnew behaviors of the current is based on the Fick-Jacobs equation in which the\nentropic barrier and the effective diffusion coefficient depend on time. The\nphenomenon observed could be used to optimize transport in microfluidic devices\nor biological channels.",
        "positive": "Axisymmetry of critical points for the Onsager functional: A simple proof is given of the classical result due to Fatkullin and\nSlastikov (2005), Liu, Zhang and Zhang (2005) that critical points for the\nOnsager functional with the Maier-Saupe molecular interaction are axisymmetric,\nincluding the case of stable critical points with an additional dipole-dipole\ninteraction (Zhou et al 2007). The proof avoids spherical polar coordinates,\ninstead using an integral identity on the sphere $S^2$. For general\ninteractions with absolutely continuous kernels the smoothness of all critical\npoints is established, generalizing a result of Vollmer (2016) for the Onsager\ninteraction. It is also shown that non-axisymmetric critical points exist for a\nwide variety of interactions including that of Onsager."
    },
    {
        "anchor": "Non-Gaussian diffusion near surfaces: We study the diffusion of particles confined close to a single wall and in\ndouble-wall planar channel geometries where the local diffusivities depend on\nthe distance to the boundaries. Displacement parallel to the walls is Brownian\nas characterized by its variance, but it is non-Gaussian having a non-zero\nfourth cumulant. Establishing a link with Taylor dispersion, we calculate the\nfourth cumulant and the tails of the displacement distribution for general\ndiffusivity tensors along with potentials generated by either the walls or\nexternally, for instance gravity. Experimental and numerical studies of the\nmotion of a colloid in the direction parallel to the wall give measured fourth\ncumulants which are correctly predicted by our theory. Interestingly, contrary\nto models of Brownian-yet-non-Gaussian diffusion, the tails of the displacement\ndistribution are shown to be Gaussian rather than exponential. All together,\nour results provide additional tests and constraints for the inference of force\nmaps and local transport properties near surfaces.",
        "positive": "Nonlinear electro-osmosis in dilute non-adsorbing polymer solutions with\n  low ionic strength: Nonlinear behavior of electro-osmosis in dilute non-adsorbing polymer\nsolutions with low salinity is investigated with Brownian dynamics simulations\nand a kinetic theory. In the Brownian simulations, the hydrodynamic interaction\nbetween the polymers and a no-slip wall is considered with Rotne-Prager\napproximation of Blake tensor. In a plug flow under a sufficiently strong\napplied electric field, the polymer migrates toward the bulk, forming a\ndepletion layer thicker than the equilibrium one. Consequently, the\nelectro-osmotic mobility increases nonlinearly with the electric field and gets\nsaturated. This nonlinear mobility qualitatively does not depend on the details\nof rheological properties of the polymer solution. Analytical calculation of\nthe kinetic theory for the same system reproduces quantitatively well the\nresults of the Brownian dynamics simulation."
    },
    {
        "anchor": "Internal friction and mode relaxation in a simple chain model: We consider equilibrium relaxation properties of the end-to-end distance and\nof principal components in a one-dimensional polymer chain model with nonlinear\ninteraction between the beads. While for the single-well potentials these\nproperties are similar to the ones of a Rouse chain, for the double-well\ninteraction potentials, modeling internal friction, they differ vastly from the\nones of the harmonic chain at intermediate times and intermediate temperatures.\nThis minimal description within a one-dimensional model mimics the relaxation\nproperties found in much more complex polymer systems. Thus, the relaxation\ntime of the end-to-end distance may grow by orders of magnitude at intermediate\ntemperatures. The principal components (whose directions are shown to coincide\nwith the normal modes of the harmonic chain, whatever interaction potential is\nassumed) not only display larger relaxation times but also subdiffusive\nscaling.",
        "positive": "Dynamics of Living Polymers: We study theoretically the dynamics of living polymers which can add and\nsubtract monomer units at their live chain ends. The classic example is ionic\nliving polymerization. In equilibrium, a delicate balance is maintained in\nwhich each initiated chain has a very small negative average growth rate\n(``velocity'') just sufficient to negate the effect of growth rate\nfluctuations. This leads to an exponential molecular weight distribution (MWD)\nwith mean Nbar. After a small perturbation of relative amplitude epsilon, e.g.\na small temperature jump, this balance is destroyed: the velocity acquires a\nboost greatly exceeding its tiny equilibrium value. For epsilon > epsilon_c =\n1/Nbar^{1/2} the response has 3 stages: (1) Coherent chain growth or shrinkage,\nleaving a highly non-linear hole or peak in the MWD at small chain lengths.\nDuring this episode, lasting time taufast ~ Nbar, the MWD's first moment and\nmonomer concentration m relax very close to equilibrium. (2) Hole-filling (or\npeak decay) after taufill ~ epsilon^2 Nbar^2. The absence or surfeit of small\nchains is erased. (3) Global MWD shape relaxation after tauslow ~ Nbar^2. By\nthis time second and higher MWD moments have relaxed. During episodes (2) and\n(3) the fast variables (Nbar,m) are enslaved to the slowly varying number of\nfree initiators (chains of zero length). Thus fast variables are\nquasi-statically fine-tuned to equilibrium. The outstanding feature of these\ndynamics is their ultrasensitivity: despite the perturbation's linearity, the\nresponse is non-linear until the late episode (3). For very small\nperturbations, epsilon < epsilon_c, response remains non-linear but with a less\ndramatic peak or hole during episode (1). Our predictions are in agreement with\nviscosity measurements on the most widely studied system, alpha-methylstyrene."
    },
    {
        "anchor": "First-order phase transitions in two-dimensional off-lattice liquid\n  crystals: We consider an off-lattice liquid crystal pair potential in strictly two\ndimensions. The potential is purely repulsive and short-ranged. Nevertheless,\nby means of a single parameter in the potential, the system is shown to undergo\na first-order phase transition. The transition is studied using mean-field\ndensity functional theory, and shown to be of the isotropic-to-nematic kind. In\naddition, the theory predicts a large density gap between the two coexisting\nphases. The first-order nature of the transition is confirmed using computer\nsimulation and finite-size scaling. Also presented is an analysis of the\ninterface between the coexisting domains, including estimates of the line\ntension, as well as an investigation of anchoring effects.",
        "positive": "Marginally compact phase and ordered ground states in a model polymer\n  with side spheres: We present the results of a quantitative study of the phase behavior of a\nmodel polymer chain with side spheres using two independent computer simulation\ntechniques. We find that the mere addition of side spheres results in key\nmodifications of standard polymer behavior. One obtains a novel marginally\ncompact phase at low temperatures, the structures in this phase are reduced in\ndimensionality and are ordered, they include strands assembled into sheets and\na variety of helices, and at least one of the transitions on lowering the\ntemperature to access these ordered states is found to be first order. Our\nmodel serves to partially bridge conventional polymer phases with biomolecular\nphases."
    },
    {
        "anchor": "Building up DNA, bit by bit: a simple description of chain assembly: We simulate the assembly of DNA copolymers from two types of short duplexes\n(short double strands with a single-stranded overhang at each end), as\ndescribed by the oxDNA model. We find that the statistics of chain lengths can\nbe well reproduced by a simple theory that treats the association of particles\ninto ideal (i.e., non-interacting) clusters as a reversible chemical reaction.\nThe reaction constants can be predicted either from Santalucia's theory or from\nWertheim's thermodynamic perturbation theory of association for spherical\npatchy particles. Our results suggest that theories incorporating very limited\nmolecular detail may be useful for predicting the broad equilibrium features of\ncopolymerisation.",
        "positive": "Characterisation and optimisation of foams for varicose vein\n  sclerotherapy: In this study we characterise the properties of foams used for varicose vein\nsclerotherapy. Their effectiveness is evaluated by predicting their yield\nstress and their flow profiles within a model of a vein. This information is\nrepresented using a Bingham number, which also takes into account the foam\nliquid fraction and the Sauter mean of the bubble size distribution. Based on\nthis modelling, the most effective foams have a Bingham number B = 600 for a\nvein of diameter 2mm, in addition to a narrow bubble size distribution."
    },
    {
        "anchor": "Assembly and speed control in ion exchange based modular phoretic\n  micro-swimmers: We report an experimental study on ion-exchange based modular micro-swimmers\nin low-salt water. Cationic ion-exchange particles and passive cargo particles\nassemble into self-propelling complexes, showing self-propulsion at speeds of\nseveral microns per second over extended distances and times. We quantify the\nassembly and speed of the complexes for different combinations of ion exchange\nparticles and cargo particles, substrate types, salt types and concentrations,\nand cell geometries. Irrespective of experimental boundary conditions, we\nobserve a regular development of the assembly shape with increasing number of\ncargo. Moreover, the swimming speed increases stepwise upon increasing the\nnumber of cargo and then saturates at a maximum speed, indicating an active\nrole of cargo in modular swimming. We propose a geometric model of\nself-assembly to describe the experimental observations in a qualitative way.\nOur study also provides some constraints for future theoretical modelling and\nsimulation.",
        "positive": "Thermal diffusion segregation of an impurity in a driven granular fluid: We study segregation of an impurity in a driven granular fluid under two\ntypes of \\emph{steady} states. In the first state, the granular gas is driven\nby a stochastic volume force field with a Fourier-type profile while in the\nsecond state, the granular gas is sheared in such a way that inelastic cooling\nis balanced by viscous heating. We compare theoretical results derived from a\nsolution of the (inelastic) Boltzmann equation at Navier-Stokes (NS) order with\nthose obtained from the Direct Monte Carlo simulation (DSMC) method and\nmolecular dynamics (MD) simulations. Good agreement is found between theory and\nsimulation, which provides strong evidence of the reliability of NS granular\nhydrodynamics for these steady states (including the dynamics of the impurity),\neven at high inelasticities. In addition, preliminary results for thermal\ndiffusion in granular fluids at moderate densitis are also presented. As for\ndilute gases \\cite{VGK14}, excellent agreement is also found in this more\ngeneral case."
    },
    {
        "anchor": "Simple crystallizable bead-spring polymer model: We develop a simple coarse-grained bead-spring polymer model exhibiting\ncompeting crystallization and glass transitions. For quench rates slower than\nthe critical nucleation rate $|\\dot{T}|_{crit}$, systems exhibit a first-order\ncrystallization transition below a critical temperature $T=T_{cryst}$. Such\nsystems form close-packed crystallites of FCC and/or HCP order, separated by\ndomain walls, twin defects, and an amorphous interphase. The size of amorphous\nregions grows continuously as the quench rate $|\\dot{T}|$ increases, producing\nnearly amorphous structure for $|\\dot{T}|>|\\dot{T}|_{crit}$. Our model exhibits\nmany features observed in recent studies of crystallization of athermal polymer\npackings, but also critical differences arising from the softness of the pair\ninteractions and the thermal nature of the phase transition. The model is\nconsiderably more computationally efficient than other recent crystallizable\ncoarse-grained polymer models; while it sacrifices some features of real\nsemicrystalline polymers (such as lamellar structure and chain\ndisentanglement), we anticipate that it will serve as a useful model for\nstudying generic features related to semicrystalline order in polymer solids.",
        "positive": "Field Theoretic Study of Bilayer Membrane Fusion III: Membranes with\n  Leaves of Different Composition: We extend previous work on homogeneous bilayers to calculate the barriers to\nfusion of planar bilayers which contain two different amphiphiles, a\nlamellae-former and a hexagonal former, with different compositions of the\ntwoin each leaf. Self-consistent field theory is employed, and both standard\nand alternative pathways are explored. We first calculate these barriers as the\namount of hexagonal former is increased equally in both leaves to levels\nappropriate to the plasma membrane of human red blood cells. We follow these\nbarriers as the composition of hexagonal-formers is then increased in the cis\nlayer and decreased in the trans layer, again to an extent comparable to the\nbiological system. We find that, while the fusion pathway exhibits two barriers\nin both the standard and alternative pathways, in both cases the magnitudes of\nthese barriers are comparable to one another, and small, on the order of 13 kT.\nAs a consequence, one expects that once the bilayers are brought sufficiently\nclose to one another to initiate the process, fusion should occur rapidly."
    },
    {
        "anchor": "Nanofluidics coming of age: This is a turning point for nanofluidics. Recent progress allows envisioning\nboth fundamental discoveries for the transport of fluids at the ultimate\nscales, and disruptive technologies for the water-energy nexus.",
        "positive": "Clogging transition and anomalous transport in driven suspensions in a\n  disordered medium: We study computationally the dynamics of forced, Brownian particles through a\ndisordered system. As the concentration of mobile particles and/or fixed\nobstacles increase, we characterize the different regimes of flow and address\nhow clogging develops. We show that clogging is preceded by a wide region of\nanomalous transport, characterized by a power law decay of intermittent bursts.\nWe analyze the velocity distribution of the moving particles and show that this\nabnormal flow region is characterized by a coexistence between mobile and\narrested particles, and their relative populations change smoothly as clogging\nis approached. The comparison of the regimes of anomalous transport and\nclogging with the corresponding scenarios of particles pushed through a single\nbottleneck show qualitatively the same trends highlighting the generality of\nthe transport regimes leading to clogging."
    },
    {
        "anchor": "Shear jamming and fragility in dense suspensions: The phenomenon of shear-induced jamming is a factor in the complex\nrheological behavior of dense suspensions. Such shear-jammed states are\nfragile, i.e., they are not stable against applied stresses that are\nincompatible with the stress imposed to create them. This peculiar flow-history\ndependence of the stress response is due to flow-induced microstructures. To\nexamine jammed states realized under constant shear stress, we perform dynamic\nsimulations of non-Brownian particles with frictional contact forces and\nhydrodynamic lubrication forces. We find clear signatures that distinguish\nthese fragile states from the more conventional isotropic jammed states.",
        "positive": "Dispersion of acoustic excitations in tetrahedral liquids: Investigation of the longitudinal and transverse excitations in liquids is of\ngreat importance for understanding the fundamentals of the liquid state of\nmatter. One of the important questions is the temperature and density\ndependence of the frequency of the excitations. In our recent works it was\nshown that while in simple liquids the frequency of longitudinal excitations\nincreases when the temperature is increased isochorically, in water the\nfrequency can anomalously decrease with the temperature increase. In the\npresent manuscript we study the dispersion curves of longitudinal and\ntransverse excitations of water and liquid silicon modelled by Stillinger-Weber\npotential. We show that both substances demonstrate the anomaly of the\ndispersion curves, but it the case of water it is more pronounced."
    },
    {
        "anchor": "Surface tension and Laplace pressure in triangulated surface models for\n  membranes without fixed boundary: A Monte Carlo (MC) study is performed to evaluate the surface tension $\\gamma\n$ of spherical membranes that may be regarded as the models of the lipid\nlayers. We use the canonical surface model defined on the self-avoiding\ntriangulated lattices. The surface tension $\\gamma $ is calculated by keeping\nthe total surface area $A$ constant during the MC simulations. In the\nevaluation of $\\gamma $, we use $A$ instead of the projected area $A_p$, which\nis unknown due to the fluctuation of the spherical surface without boundary.\nThe pressure difference ${\\it\\Delta}p $ between the inner and the outer sides\nof the surface is also calculated by maintaining the enclosed volume constant.\nUsing ${\\it\\Delta}p $ and the Laplace formula, we obtain the tension, which is\nconsidered to be equal to the frame tension $\\tau$ conjugate to $A_p$, and\ncheck whether or not $\\gamma $ is consistent with $\\tau$. We find reasonable\nconsistency between $\\gamma$ and $\\tau$ in the region of sufficiently large\nbending rigidity $\\kappa$ or sufficiently large $A/N$. It is also found that\n$\\tau$ becomes constant in the limit of $A/N\\to \\infty$ both in the tethered\nand fluid surfaces.",
        "positive": "The Vortex Kinetics of Conserved and Non-conserved O(n) Models: We study the motion of vortices in the conserved and non-conserved\nphase-ordering models. We give an analytical method for computing the speed and\nposition distribution functions for pairs of annihilating point vortices based\non heuristic scaling arguments. In the non-conserved case this method produces\na speed distribution function consistent with previous analytic results. As two\nspecial examples, we simulate the conserved and non-conserved O(2) model in two\ndimensional space numerically. The numerical results for the non-conserved case\nare consistent with the theoretical predictions. The speed distribution of the\nvortices in the conserved case is measured for the first time. Our theory\nproduces a distribution function with the correct large speed tail but does not\naccurately describe the numerical data at small speeds. The position\ndistribution functions for both models are measured for the first time and we\nfind good agreement with our analytic results. We are also able to extend this\nmethod to models with a scalar order parameter."
    },
    {
        "anchor": "A Variational Sum-Rule Approach to Collective Excitations of a Trapped\n  Bose-Einstein Condensate: It is found that combining an excitation-energy sum rule with Fetter's trial\nwave function gives almost exact low-lying collective-mode frequencies of a\ntrapped Bose-Einstein condensate at zero temperature.",
        "positive": "Odd elasticity of a catalytic micromachine: We perform numerical simulations of a model micromachine driven by catalytic\nchemical reactions. Our model includes a mechano-chemical coupling between the\nstructural variables and the nonequilibrium variable describing the catalytic\nreactions. The time-correlation functions of the structural variables are\ncalculated and further analyzed in terms of odd Langevin dynamics. We obtain\nthe effective odd elastic constant that manifests the broken time-reversal\nsymmetry of a catalytic micromachine. Within the simulation, we separately\nestimate the quantity called nonreciprocality and show that its behavior is\nsimilar to that of the odd elasticity.Our approach suggests a new method to\nextract the nonequilibrium properties of a micromachine only by measuring its\nstructural dynamics."
    },
    {
        "anchor": "Ionic Size Effects on the Poisson-Boltzmann Theory: In this paper we develop a simple theory to study the effects of ionic size\non ionic distributions around a charged spherical particle. We include a\ncorrection to the regular Poisson-Boltzmann equation in order to take into\naccount the size of ions in a mean-field regime. The results are compared with\nMonte Carlo simulations and a Density Functional Theory based on the\nFundamental Measure approach and a second-order bulk expansion which accounts\nfor electrostatic correlations. The agreement is very good even for multivalent\nions. Our results show that the theory can be applied with very good accuracy\nin the description of ions with high effective ionic radii and low\nconcentration, interacting with a colloid or nanoparticle in an electrolyte\nsolution.",
        "positive": "Descriptions of membrane mechanics from microscopic and effective\n  two-dimensional perspectives: Mechanics of fluid membranes may be described in terms of the concepts of\nmechanical deformations and stresses, or in terms of mechanical free-energy\nfunctions. In this paper, each of the two descriptions is developed by viewing\na membrane from two perspectives: a microscopic perspective, in which the\nmembrane appears as a thin layer of finite thickness and with highly\ninhomogeneous material and force distributions in its transverse direction, and\nan effective, two-dimensional perspective, in which the membrane is treated as\nan infinitely thin surface, with effective material and mechanical properties.\nA connection between these two perspectives is then established. Moreover, the\nfunctional dependence of the variation in the mechanical free energy of the\nmembrane on its mechanical deformations is first studied in the microscopic\nperspective. The result is then used to examine to what extent different,\neffective mechanical stresses and forces can be derived from a given, effective\nfunctional of the mechanical free energy."
    },
    {
        "anchor": "How are mobility and friction related in viscoelastic fluids?: The motion of a colloidal probe in a viscoelastic fluid is described by\nfriction or mobility, depending on whether the probe is moving with a velocity\nor feeling a force. While the Einstein relation describes an inverse\nrelationship valid for Newtonian solvents, both concepts are generalized to\ntime-dependent memory kernels in viscoelastic fluids. We theoretically and\nexperimentally investigate their relation by considering two observables: the\nrecoil after releasing a probe that was moved through the fluid and the\nequilibrium mean squared displacement (MSD). Applying concepts of linear\nresponse theory, we generalize Einstein's relation and thereby relate recoil\nand MSD, which both provide access to the mobility kernel. With increasing\nconcentration, however, MSD and recoil show distinct behaviors, rooted in\ndifferent behaviors of the two kernels. Using two theoretical models, a linear\ntwo-bath particle model and hard spheres treated by mode-coupling theory, we\nfind a Volterra relation between the two kernels, explaining differing\ntimescales in friction and mobility kernels under variation of concentration.",
        "positive": "Evaporation-triggered Wetting Transition for Water Droplets upon\n  Hydrophobic Microstructures: When placed on rough hydrophobic surfaces, water droplets of diameter larger\nthan a few millimeters can easily form pearls, as they are in the Cassie-Baxter\nstate with air pockets trapped underneath the droplet. Intriguingly, a natural\nevaporating process can drive such a Fakir drop into a completely wetting\n(Wenzel) state. Our microscopic observations with simultaneous side and bottom\nviews of evaporating droplets upon transparent hydrophobic microstructures\nelucidate the water-filling dynamics and the mechanism of this\nevaporation-triggered transition. For the present material the wetting\ntransition occurs when the water droplet size decreases to a few hundreds of\nmicrometers in radius. We present a general global energy argument which\nestimates the interfacial energies depending on the drop size and can account\nfor the critical radius for the transition."
    },
    {
        "anchor": "Understanding the determinants of stability and folding of small\n  globular proteins from their energetics: The results of minimal model calculations suggest that the stability and the\nkinetic accessibility of the native state of small globular proteins are\ncontrolled by few \"hot\" sites. By mean of molecular dynamics simulations around\nthe native conformation, which simulate the protein and the surrounding solvent\nat full--atom level, we generate an energetic map of the equilibrium state of\nthe protein and simplify it with an Eigenvalue decomposition. The components of\nthe Eigenvector associated with the lowest Eigenvalue indicate which are the\n\"hot\" sites responsible for the stability and for the fast folding of the\nprotein. Comparison of these predictions with the results of mutatgenesis\nexperiments, performed for five small proteins, provide an excellent agreement.",
        "positive": "Knotted Nematics: Knotted line defects in continuous fields entrain a complex arrangement of\nthe material sur- rounding them. Recent experimental realisations in optics,\nfluids and nematic liquid crystals make it important to fully characterise\nthese textures and to understand how their properties relate to the knot type.\nWe characterise knotted nematics through an application of classical knot\ntheory founded upon the Pontryagin-Thom construction for nematic textures and\ngive explicit closed form constructions for knots possessing Milnor fibrations\nwith general boundary conditions. For links we construct nematic textures\ncorresponding to all possible assigments of linking numbers and discuss the\nrelevance to recent, and classic, experiments on Hopf links."
    },
    {
        "anchor": "Spatial correlations of hydrodynamic fluctuations in simple fluids under\n  shear flow: A mesoscale simulation study: Hydrodynamic fluctuations in simple fluids under shear flow are demonstrated\nto be spatially correlated, in contrast to the fluctuations at equilibrium,\nusing mesoscopic hydrodynamic simulations. The simulation results for the\nequal-time hydrodynamic correlations in a multiparticle collision dynamics\n(MPC) fluid in shear flow are compared with the explicit expressions obtained\nfrom fluctuating hydrodynamic calculations. For large wave vectors $k$, the\nnonequlibrium contributions to transverse and longitudinal velocity\ncorrelations decay as $k^{-4}$ for wave vectors along the flow direction, and\nas $k^{-2}$ for the off-flow directions. For small wave vectors, a cross-over\nto a slower decay occurs, indicating long-range correlations in real space. The\ncoupling between the transverse velocity components, which vanishes at\nequilibrium, also exhibits a $k^{-2}$ dependence on the wave vector. In\naddition, we observe a quadratic dependency on the shear rate of the\nnon-equilibrium contribution to pressure.",
        "positive": "Deep Learning for Automated Classification and Characterization of\n  Amorphous Materials: It is difficult to quantify structure-property relationships and to identify\nstructural features of complex materials. The characterization of amorphous\nmaterials is especially challenging because their lack of long-range order\nmakes it difficult to define structural metrics. In this work, we apply deep\nlearning algorithms to accurately classify amorphous materials and characterize\ntheir structural features. Specifically, we show that convolutional neural\nnetworks and message passing neural networks can classify two-dimensional\nliquids and liquid-cooled glasses from molecular dynamics simulations with\ngreater than 0.98 AUC, with no a priori assumptions about local particle\nrelationships, even when the liquids and glasses are prepared at the same\ninherent structure energy. Furthermore, we demonstrate that message passing\nneural networks surpass convolutional neural networks in this context in both\naccuracy and interpretability. We extract a clear interpretation of how message\npassing neural networks evaluate liquid and glass structures by using a\nself-attention mechanism. Using this interpretation, we derive three novel\nstructural metrics that accurately characterize glass formation. The methods\npresented here provide us with a procedure to identify important structural\nfeatures in materials that could be missed by standard techniques and give us a\nunique insight into how these neural networks process data."
    },
    {
        "anchor": "Fluid heterogeneity detection based on the asymptotic distribution of\n  the time-averaged mean squared displacement in single particle tracking\n  experiments: A tracer particle is called anomalously diffusive if its mean squared\ndisplacement grows approximately as $\\sigma^2 t^{\\alpha}$ as a function of time\n$t$ for some constant $\\sigma^2$, where the diffusion exponent satisfies\n$\\alpha \\neq 1$. In this article, we use recent results on the asymptotic\ndistribution of the time-averaged mean squared displacement (Didier and Zhang\n(2017)) to construct statistical tests for detecting physical heterogeneity in\nviscoelastic fluid samples starting from one or multiple observed anomalously\ndiffusive paths. The methods are asymptotically valid for the range $0 < \\alpha\n< 3/2$ and involve a mathematical characterization of time-averaged mean\nsquared displacement bias and the effect of correlated disturbance errors. The\nassumptions on particle motion cover a broad family of fractional Gaussian\nprocesses, including fractional Brownian motion and many fractional instances\nof the generalized Langevin equation framework. We apply the proposed methods\nin experimental data from treated $P.\\ aeruginosa$ biofilms generated by the\ncollaboration of the Hill and Schoenfisch Labs at UNC-Chapel Hill.",
        "positive": "Topology of Force Networks in Granular Media under Impact: We investigate the evolution of the force network in experimental systems of\ntwo-dimensional granular materials under impact. We use the first Betti number,\n$\\beta_1$, and persistence diagrams, as measures of the topological properties\nof the force network. We show that the structure of the network has a complex,\nhysteretic dependence on both the intruder acceleration and the total force\nresponse of the granular material. $\\beta_1$ can also distinguish between the\nnonlinear formation and relaxation of the force network. In addition, using the\npersistence diagram of the force network, we show that the size of the loops in\nthe force network has a Poisson-like distribution, the characteristic size of\nwhich changes over the course of the impact."
    },
    {
        "anchor": "Temperature scaling in a dense vibro-fluidised granular material: The leading order \"temperature\" of a dense two dimensional granular material\nfluidised by external vibrations is determined. An asymptotic solution is\nobtained where the particles are considered to be elastic in the leading\napproximation. The velocity distribution is a Maxwell-Boltzmann distribution in\nthe leading approximation. The density profile is determined by solving the\nmomentum balance equation in the vertical direction, where the relation between\nthe pressure and density is provided by the virial equation of state. The\npredictions of the present analysis show good agreement with simulation results\nat higher densities where theories for a dilute vibrated granular material,\nwith the pressure-density relation provided by the ideal gas law, are in error.\nThe theory also predicts the scaling relations of the total dissipation in the\nbed reported by McNamara and Luding (PRE v 58, p 813).",
        "positive": "Formation of Chain-Folded Structures from Supercooled Polymer Melts: The formation of chain-folded structures from the melt is observed in\nmolecular dynamics simulations resembling the lamellae of polymer crystals.\nCrystallization and subsequent melting temperatures are related linearly to the\ninverse lamellar thickness. Analysis of the single chain conformations in the\ncrystal shows that most chains reenter the same lamella by tight backfolds.\nSimulations are performed with a mesoscopic bead-spring model including a\nspecific angle bending potential. They demonstrate that chain stiffness alone,\nwithout an attractive inter-particle potential, is a sufficient driving force\nfor the formation of chain-folded lamellae."
    },
    {
        "anchor": "Core-shell droplets and microcapsules formed through liquid-liquid phase\n  separation of a colloid-polymer mixture: Microcapsules allow for the controlled containment, transport, and release of\ncargoes ranging from pharmaceuticals to fragrances. Given the interest from a\nvariety of industries in microcapsules and other core-shell structures, a\nmultitude of fabrication strategies exist. Here, we report on a method relying\non a mixture of temperature-responsive microgel particles,\npoly(N-isopropylacrylamide) (pNIPAM), and a polymer which undergo fluid-fluid\nphase separation. At room temperature this mixture separates into colloid-rich\n(liquid) and colloid-poor (gas) fluids. By heating the sample above a critical\ntemperature where the microgel particles shrink dramatically and develop a more\ndeeply attractive interparticle potential, the droplets of the colloid-rich\nphase become gel-like. As the temperature is lowered back to room temperature,\nthese droplets of gelled colloidal particles reliquefy and phase separation\nwithin the droplet occurs. This phase separation leads to colloid-poor droplets\nwithin the colloid-rich droplets surrounded by a continuous colloid-poor phase.\nThe gas/liquid/gas all-aqueous double emulsion lasts only a few minutes before\na majority of the inner droplets escape. However, the colloid-rich shell of the\ncore-shell droplets can solidify with the addition of salt. That this method\ncreates a core-shell structures with a shell composed of stimuli-sensitive\nmicrogel colloidal particles using only aqueous components makes it attractive\nfor encapsulating biological materials and making capsules that respond to\nchanges in, for example, temperature, salt concentration, or pH.",
        "positive": "Non-equilibrium Kinetics of the Transformation of Liquids into Physical\n  Gels: A major stumbling block for statistical physics and materials science has\nbeen the lack of a uni- versal principle that allows us to understand and\npredict elementary structural, morphological, and dynamical properties of\nnon-equilibrium amorphous states of matter. The recently-developed non-\nequilibrium self-consistent generalized Langevin equation (NE-SCGLE) theory,\nhowever, has been shown to provide a fundamental tool for the understanding of\nthe most essential features of the transformation of liquids into amorphous\nsolids, such as their aging kinetics or their dependence on the protocol of\nfabrication. In this work we focus on the predicted kinetics of one of the main\nfingerprints of the formation of gels by arrested spinodal decomposition of\nsuddenly and deeply quenched simple liquids, namely, the arrest of structural\nparameters associated with the morpho- logical evolution from the initially\nuniform fluid, to the dynamically arrested sponge-like amorphous material. The\ncomparison of the theoretical predictions (based on a simple specific model\nsystem), with simulation and experimental data measured on similar but more\ncomplex materials, suggests the universality of the predicted scenario."
    },
    {
        "anchor": "Entrainment and scattering in microswimmer--colloid interactions: We use boundary element simulations to study the interaction of model\nmicroswimmers with a neutrally buoyant spherical particle. The ratio of the\nsize of the particle to that of the swimmer is varied from $R^\\mathrm{P} /\nR^\\mathrm{S} \\ll 1$, corresponding to swimmer--tracer scattering, to\n$R^\\mathrm{P} / R^\\mathrm{S} \\gg 1$, approximately equivalent to the swimmer\ninteracting with a fixed, flat surface. We find that details of the swimmer and\nparticle trajectories vary for different swimmers. However, the overall\ncharacteristics of the scattering event fall into two regimes, depending on the\nrelative magnitudes of the impact parameter, $\\rho$, and the collision radius,\n$R^\\mathrm{coll}=R^\\mathrm{P} + R^\\mathrm{S}$. The range of particle motion,\ndefined as the maximum distance between two points on the trajectory, has only\na weak dependence on the impact parameter when $\\rho < R^\\mathrm{coll}$ and\ndecreases with the radius of the particle. In contrast, when\n$\\rho>R^\\mathrm{coll}$ the range decreases as a power law in $\\rho$ and is\ninsensitive to the size of the particle. We also demonstrate that large\nparticles can cause swimmers to be deflected through large angles. In some\ninstances, this swimmer deflection can lead to larger net displacements of the\nparticle. Based on these results, we estimate the effective diffusivity of a\nparticle in a dilute bath of swimmers and show that there is a non-monotonic\ndependence on particle radius. Similarly, we show that the effective\ndiffusivity of a swimmer scattering in a suspension of particles varies\nnon-monotonically with particle radius.",
        "positive": "Experimental Test of the \"Isotropic\" Approximation for Granular\n  Materials using p=constant Compression: Experimental data from axially symmetric compression test at constant mean\npressure p on Hostun sand from Bouvard experiments are used to study the\nvalidity of an \"isotropic\" modelling as a function of the density .The\nisotropic assumption is found to be quite good for loose samples and/or in the\nrange of large pressure. For smaller mean pressure, anisotropic response is\nobserved at few percents of axial deformation. Relation with anisotropic\ndistribution of local force is made. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn"
    },
    {
        "anchor": "Modeling of Branched Thickening Polymers under Poiseuille Flow Gives\n  Clues as to how to Increase a Solvent Viscosity: The viscosity enhancement of a solvent produced by the addition of thickening\nbranched polymers is predicted as a function of polymer concentration, branch\nlength and persistence length, and strength of the covalent bonding\ninteractions. Non equilibrium, stationary state Poiseuille numerical\nsimulations are performed using the dissipative particle dynamics model to\nobtain the viscosity of the fluid. It is found that the clustering of the\npolymers into aggregates raises the viscosity and that it is more strongly\naffected by the strength of the bonding interactions. General scaling\nrelationships are found for the viscosity as a function of the variables\nstudied, which are expected to be useful for the design and synthesis of new\nviscosifying polymers. It is argued that our results can be applied to aqueous\nthickeners, of importance for colloidal fluids such as paints and coatings, and\nalso for nonpolar fluids such as supercritical CO2, which is a promising non\nhydraulic fracking fluid also useful in enhanced oil recovery.",
        "positive": "Effect of temperature and glycerol on the hydrogen-bond dynamics of\n  water: The effect of glycerol, water and glycerol-water binary mixtures on the\nstructure and dynamics of biomolecules has been well studied. However, a lot\nremains to be learned about the effect of varying glycerol concentration and\ntemperature on the dynamics of water. We have studied the effect of\nconcentration and temperature on the hydrogen bonded network formed by water\nmolecules. A strong correlation between the relaxation time of the network and\naverage number of hydrogen bonds per water molecules was found. The radial\ndistribution function of water oxygen and hydrogen atoms clarifies the effect\nof concentration on the structure and clustering of water."
    },
    {
        "anchor": "Dynamics of active particles with space-dependent swim velocity: We study the dynamical properties of an active particle subject to a swimming\nspeed explicitly depending on the particle position. The oscillating spatial\nprofile of the swim velocity considered in this paper takes inspiration from\nexperimental studies based on Janus particles whose speed can be modulated by\nan external source of light. We suggest and apply an appropriate model of an\nactive Ornstein Uhlenbeck particle to the present case. This allows us to\npredict the stationary properties, by finding the exact solution of the\nsteady-state probability distribution of particle position and velocity. From\nthis, we obtain the spatial density profile and show that its form is\nconsistent with the one found in the framework of other popular models. The\nreduced velocity distribution highlights the emergence of non-Gaussianity in\nour generalized AOUP model which becomes more evident as the spatial dependence\nof the velocity profile becomes more pronounced. Then, we focus on the\ntime-dependent properties of the system. Velocity autocorrelation functions are\nstudied in the steady-state combining numerical and analytical methods derived\nunder suitable approximations. We observe a non-monotonic decay in the temporal\nshape of the velocity autocorrelation function which depends on the ratio\nbetween the persistence length and the spatial period of the swim velocity.\nFinally, we numerically and analytically study the mean square displacement and\nthe long-time diffusion coefficient. The ballistic regime, observed in the\nsmall-time region, is deeply affected by the properties of the swim velocity\nlandscape which induces also a crossover to a sub-ballistic but superdiffusive\nregime for intermediate times. Finally, the long-time diffusion coefficient\ndecreases as the amplitude of the swim velocity oscillations increases because\nthe diffusion is determined by those regions where the particles are slow.",
        "positive": "Charged elastic rings: deformation and dynamics: We report the counter-intuitive instability of charged elastic rings, and the\npersistence of sinusoidal deformations in the lowest-energy configurations by\nthe combination of high-precision numerical simulations and analytical\nperturbation calculation. We also study the dynamical evolution of the charged\nring under random disturbance, and reveal the modulation of the dominant\nfrequencies by the electrostatic force. The purely mechanical analysis of the\nclassical ring system presented in this work yields insights into the subtlety\nof long-range forces in the organization and dynamics of matter."
    },
    {
        "anchor": "Kinetic phase diagrams of a ternary hard sphere mixture: We use the Self Consisten Generalized Langevin Equation theory (SCGLE) to\nstudy the dynamic arrest transitions of a system of three species of hard\nsphere colloidal system in the size ratio 1:3:9. We find that the inclusion of\nthe smallest species has a depletion effect that drives the system to a second\nglass-liquid-glass re-entrance in a similar way that the inclusion of a small\nspecies in an otherwise monodisperse system leads to a (first) re-entrance. And\nwe also find that the new glass after the second reentrance has very small\nlocalization length. Additionally we compare the kinetic phase diagram of a\nbinary hard sphere mixture with size asymmetry 1:5, obtained with Mode Coupling\nTheory (MCT) and SCGLE theory and exhibit the significant differences between\nthe two theories.",
        "positive": "Theory for the density of interacting quasi-localised modes in amorphous\n  solids: Quasi-localised modes appear in the vibrational spectrum of amorphous solids\nat low-frequency. Though never formalised, these modes are believed to have a\nclose relationship with other important local excitations, including shear\ntransformations and two-level systems. We provide a theory for their frequency\ndensity, $D_{L}(\\omega)\\sim\\omega^{\\alpha}$, that establishes this link for\nsystems at zero temperature under quasi-static loading. It predicts two regimes\ndepending on the density of shear transformations $P(x)\\sim x^{\\theta}$ (with\n$x$ the additional stress needed to trigger a shear transformation). If\n$\\theta>1/4$, $\\alpha=4$ and a finite fraction of quasi-localised modes form\nshear transformations, whose amplitudes vanish at low frequencies. If\n$\\theta<1/4$, $\\alpha=3+ 4 \\theta$ and all quasi-localised modes form shear\ntransformations with a finite amplitude at vanishing frequencies. We confirm\nour predictions numerically."
    },
    {
        "anchor": "Activity induced isotropic-polar transition in active liquid crystals: Active fluids are intrinsically out-of-equilibrium systems due to the\ninternal energy injection of the active constituents. We show here that a\ntransition from a motion-less isotropic state towards a flowing polar one can\nbe possibly driven by the sole active injection through the action of\npolar-hydrodynamic interactions in absence of an ad hoc free-energy which\nfavors the development of an ordered phase. In particular, we propose an\nanalytical argument and we perform lattice Boltzmann simulations where the\nappearance of large temporal fluctuations in the polar fraction of the system\nis observed at the transition point. Moreover, we make use of a scale-to-scale\nanalysis to unveil the energy transfer mechanism, proving that elastic\nabsorption plays a relevant role in the overall dynamics of the system,\ncontrary to what reported in previous works on the usual active gel theory\nwhere this term could be factually neglected.",
        "positive": "Roughening of two-dimensional interfaces in nonequilibrium\n  phase-separated systems: I show that non-equilibrium two-dimensional interfaces between three\ndimensional phase separated fluids exhibit a peculiar \"sub-logarithmic\"\nroughness. Specifically, an interface of lateral extent $L$ will fluctuate\nvertically (i.e., normal to the mean surface orientation) a typical RMS\ndistance $w\\equiv\\sqrt{\\langle |h(\\br,t)|^2\\rangle} \\propto [\\ln{(L/a)}]^{1/3}$\n(where $a$ is a microscopic length, and $ h(\\br,t)$ is the height of the\ninterface at two dimensional position $\\br$ at time $t$). In contrast, the\nroughness of equilibrium two-dimensional interfaces between three dimensional\nfluids, obeys $w \\propto [\\ln{(L/a)}]^{1/2}$. The exponent $1/3$ for the active\ncase is exact. In addition, the characteristic time scales $\\tau(L)$ in the\nactive case scale according to $\\tau(L)\\propto L^3 [\\ln{(L/a)}]^{1/3}$, in\ncontrast to the simple $\\tau(L)\\propto L^3$ scaling found in equilibrium\nsystems with conserved densities and no fluid flow."
    },
    {
        "anchor": "Enhancement of mobility in an interacting colloidal system under\n  feedback control: Feedback control schemes are a promising way to manipulate transport\nproperties of driven colloidal suspensions. In the present article we suggest a\nfeedback scheme to enhance the collective transport of colloidal particles with\nrepulsive interactions through a one-dimensional tilted washboard potential.\nThe control is modelled by a harmonic confining potential, mimicking an optical\n\"trap\", with the center of this trap moving with the (instantaneous) mean\nparticle position. Our theoretical analysis is based on the Smoluchowski\nequation combined with Dynamical Density Functional Theory (DDFT) for systems\nwith hard-core or ultra-soft (Gaussian) interactions. For either type of\ninteraction we find that the feedback control can lead to an enhancement of the\nmobility by several orders of magnitude relative to the uncontrolled case. The\nlargest effects occur for intermediate stiffness of the trap and large particle\nnumbers. Moreover, in some regions of the parameter space the feedback control\ninduces oscillations of the mean velocity. Finally, we show that the\nenhancement of mobility is robust against a small time delay in implementing\nthe feedback control.",
        "positive": "On a molecular based Q-tensor model for liquid crystals with density\n  variations: In this article, we study the new Q-tensor model previously derived from\nOnsager's molecular theory by Han \\textit{et al.} [Arch. Rational Mech. Anal.,\n215.3 (2014), pp. 741-809] for static liquid crystal modeling. Taking density\nand Q-tensor as order parameters, the new Q-tensor model not only characterizes\nimportant phases while capturing density variation effects, but also remains\ncomputationally tractable and efficient. We report the results of two numerical\napplications of the model, namely the isotropic--nematic--smectic-A--smectic-C\nphase transitions and the isotropic--nematic interface problem, in which\ndensity variations are indispensable. Meanwhile, we show the connections of the\nnew Q-tensor model with classical models including generalized Landau-de Gennes\nmodels, generalized McMillan models, and the Chen-Lubensky model. The new\nQ-tensor model is the pivot and an appropriate trade-off between the classical\nmodels in three scales."
    },
    {
        "anchor": "Flow of deformable droplets: discontinuous shear thinning and velocity\n  oscillations: We study the rheology of a suspension of soft deformable droplets subjected\nto a pressure-driven flow. Through computer simulations, we measure the\napparent viscosity as a function of droplet concentration and pressure\ngradient, and provide evidence of a discontinuous shear thinning behaviour,\nwhich occurs at a concentration-dependent value of the forcing. We further show\nthat this response is associated with a nonequilibrium transition between a\n`hard' (or less deformable) phase, which is nearly jammed and flows very\nslowly, and a `soft' (or more deformable) phase, which flows much more easily.\nThe soft phase is characterised by flow-induced time dependent shape\ndeformations and internal currents, which are virtually absent in the hard\nphase. Close to the transition, we find sustained oscillations in both the\ndroplet and fluid velocities. Polydisperse systems show similar phenomenology\nbut with a smoother transition, and less regular oscillations.",
        "positive": "Viscoelastic response of sonic band-gap materials: A brief report is presented on the effect of viscoelastic losses in a high\ndensity contrast sonic band-gap material of close-packed rubber spheres in air.\nThe scattering properties of such a material are computed with an on-shell\nmultiple scattering method, properties which are compared with the lossless\ncase. The existence of an appreciable omnidirectional gap in the transmission\nspectrum, when losses are present, is also reported."
    },
    {
        "anchor": "Theoretical study of the competition between folding and contact\n  interactions on the properties of polymers using self-avoid random walk\n  algorithm: The self-avoid random walk algorithm has been extensively used in the study\nof polymers. In this work we study the basic properties of the trajectories\ngenerated with this algorithm when two interactions are added to it: contact\nand folding interaction. These interactions represent the internal forces of\nthe polymer as well as the effect of the solvent. When independently added to\nthe algorithm, the contact interaction creates the compact phase while the\nfolding one creates the extended phase. These are the consequences of the\ntypical event of each interaction. On the other hand, when this typical event\nis avoided there is no established phase on the system. When simultaneously\nadded, there is a competition between the interactions and the folding one is\ndominant over the contact one. The resulting phase is always the extended one\nwith and without the contact interaction.",
        "positive": "Single-file diffusion and kinetics of template assisted assembly of\n  colloids: We report computer simulation studies of the kinetics of ordering of a two\ndimensional system of particles on a template with a one dimensional periodic\npattern. In equilibrium one obtains a re-entrant liquid-solid-liquid phase\ntransition as the strength of the substrate potential is varied. We show that\ndomains of crystalline order grow as $\\sim t^{1/z}$, with $z \\sim 4$ with a\npossible cross-over to $z \\sim 2$ at late times. We argue that the $t^{1/4}$\nlaw originates from {\\em single-file} motion and annihilation of defect pairs\nof opposite topological charge along channels created by the template."
    },
    {
        "anchor": "Tuning the order of colloidal monolayers: assembly of heterogeneously\n  charged colloids close to a patterned substrate: We study the behavior of negatively charged colloids with two positively\ncharged polar caps close to a planar patterned surface. The competition between\nthe different anisotropic components of the particle-particle interaction\npatterns is able by itself to give rise to a rich assembly scenario: colloids\nwith charged surface patterns form different crystalline domains when adsorbed\nto a homogeneously charged substrate. Here we consider substrates composed of\nalternating (negative/neutral, positive/neutral and positive/negative) parallel\nstripes and, by means of Monte Carlo simulations, we investigate the ordering\nof the colloids on changing the number of the stripes. We show that the\nadditional competition between the two different lengths scales characterizing\nthe system ($i.e.,$ the particle interaction range and the size of the stripes)\ngives rise to a plethora of distinct particle arrangements, where some\nwell-defined trends can be observed. By accurately tuning the substrate charged\nmotif it is possible to, $e. g.,$ promote specific particles arrangements,\ndisfavor crystalline domains or induce the formation of extended, open\nclusters.",
        "positive": "Local grafting heterogeneities rule water intrusion and extrusion in\n  nanopores: Hydrophobic nanoporous materials can be intruded by water only by exerting an\nexternal action, typically increasing pressure. For some materials, water\nextrudes when the pressure is lowered again. Controlling intrusion/extrusion\nhysteresis is central in a number of technological applications, including\nmaterials for energy applications and for high performance liquid\nchromatography, and experimental techniques, as liquid porosimetry, but is\nstill far from being understood. In this work, we consider water intrusion and\nextrusion in common mesoporous materials grafted with hydrophobic chains,\nshowing that the macroscopic properties of the system are significantly\naffected by subnanometric heterogeneities in the grafting. For example,\nintrusion and extrusion pressures can vary more than 20 MPa depending on the\nchain length and density of the grafting. Coarse-grained molecular dynamics\nsimulations reveal that local changes of radius and contact angle produced by\ngrafting heterogeneities can pin the interface during intrusion or facilitate\nbubble nucleation in extrusion. These unprecedented microscopic insights can\ndirectly impact the design of energy materials and chromatography columns, as\nwell as the interpretation of porosimetry results."
    },
    {
        "anchor": "Absence of Dipole Glass Transition for Randomly Dilute Classical Ising\n  Dipoles: Dilute dipolar systems in three dimensions are expected to undergo a spin\nglass transition as the temperature decreases. Contrary to this, we find from\nWang-Landau Monte Carlo simulations that at low concentrations $x$, dipoles\nrandomly placed on a cubic lattice with dipolar interactions do not undergo a\nphase transition. We find that in the thermodynamic limit the ``glass''\ntransition temperature $T_g$ goes to zero as $1/\\sqrt{N}$ where $N$ is the\nnumber of dipoles. The entropy per particle at low temperatures is larger for\nlower concentrations ($x=4.5%$) than for higher concentrations ($x=20%$).",
        "positive": "Simulation study of a rectifying bipolar ion channel: Detailed model\n  versus reduced model: We study a rectifying mutant of the OmpF porin ion channel using both\nall-atom and reduced models. The mutant was created by Miedema et al. [Nano\nLett., 2007, 7, 2886] on the basis of the N-P semiconductor diode, in which an\nN-P junction is formed. The mutant contains a pore region with positive amino\nacids on the left-hand side and negative amino acids on the right-hand side.\nExperiments show that this mutant rectifies. Although we do not know the\nstructure of this mutant, we can build an all-atom model for it on the basis of\nthe structure of the wild type channel. Interestingly, molecular dynamics\nsimulations for this all-atom model do not produce rectification. A reduced\nmodel that contains only the important degrees of freedom (the positive and\nnegative amino acids and free ions in an implicit solvent), on the other hand,\nexhibits rectification. Our calculations for the reduced model (using the\nNernst-Planck equation coupled to Local Equilibrium Monte Carlo simulations)\nreveal a rectification mechanism that is different from that seen for\nsemiconductor diodes. The basic reason is that the ions are different in nature\nfrom electrons and holes (they do not recombine). We provide explanations for\nthe failure of the all-atom model including the effect of all the other atoms\nin the system as a noise that inhibits the response of ions (that would be\nnecessary for rectification) to the polarizing external field."
    },
    {
        "anchor": "The limits of multifunctionality in tunable networks: Nature is rife with networks that are functionally optimized to propagate\ninputs in order to perform specific tasks. Whether via genetic evolution or\ndynamic adaptation, many networks create functionality by locally tuning\ninteractions between nodes. Here we explore this behavior in two contexts:\nstrain propagation in mechanical networks and pressure redistribution in flow\nnetworks. By adding and removing links, we are able to optimize both types of\nnetworks to perform specific functions. We define a single function as a tuned\nresponse of a single \"target\" link when another, predetermined part of the\nnetwork is activated. Using network structures generated via such optimization,\nwe investigate how many simultaneous functions such networks can be programmed\nto fulfill. We find that both flow and mechanical networks display\nqualitatively similar phase transitions in the number of targets that can be\ntuned, along with the same robust finite-size scaling behavior. We discuss how\nthese properties can be understood in the context of a new class of\nconstraint-satisfaction problems.",
        "positive": "Structural and conformational dynamics of supercooled polymer melts:\n  Insights from first-principles theory and simulations: We report on quantitative comparisons between simulation results of a\nbead-spring model and mode-coupling theory calculations for the structural and\nconformational dynamics of a supercooled, unentangled polymer melt. We find\nsemiquantitative agreement between simulation and theory, except for processes\nthat occur on intermediate length scales between the compressibility plateau\nand the amorphous halo of the static structure factor. Our results suggest that\nthe onset of slow relaxation in a glass-forming melt can be described in terms\nof monomer-caging supplemented by chain connectivity. Furthermore, a unified\natomistic description of glassy arrest and of conformational fluctuations that\n(asymptotically) follow the Rouse model, emerges from our theory."
    },
    {
        "anchor": "Symmetry Breaking of Vortex Patterns in a Rotating Harmonic Potential: We numerically study the symmetry breaking instabilities of vortex patterns\nin a rotating harmonic potential using a type of Ginzburg-Landau equation. The\nconfigurations of vortex lattices change markedly by the symmetry-breaking\ninstabilities, and then, some vortices move away from the confinement\npotential, which leads to the annihilation of vortices. The symmetry-breaking\ninstabilities and the instabilities of vortex nucleation determine the\nparameter region of stable vortex patterns. We verify that the\nsymmetry-breaking instabilities also occur in a type of complex Ginzburg-Landau\nequation.",
        "positive": "Propulsion driven by self-oscillation via an electrohydrodynamic\n  instability: Oscillations of flagella and cilia play an important role in biology, which\nmotivates the idea of functional mimicry as part of bio-inspired applications.\nNevertheless, it still remains challenging to drive their artificial\ncounterparts to oscillate via a steady, homogeneous stimulus. Combining theory\nand simulations, we demonstrate a strategy to achieve this goal by using an\nelasto-electro-hydrodynamic instability. In particular, we show that applying a\nuniform DC electric field can produce self-oscillatory motion of a microrobot\ncomposed of a dielectric particle and an elastic filament. Upon tuning the\nelectric field and filament elasticity, the microrobot exhibits three distinct\nbehaviors: a stationary state, undulatory swimming and steady spinning, where\nthe swimming behavior stems from an instability emerging through a Hopf\nbifurcation. Our results imply the feasibility of engineering self-oscillations\nby leveraging the elasto-viscous response to control the type of bifurcation\nand the form of instability. We anticipate that our strategy will be useful in\na broad range of applications imitating self-oscillatory natural phenomena and\nbiological processes."
    },
    {
        "anchor": "Fluid laminarization in protein-based high internal phase emulsions\n  process: Protein-based high internal phase emulsions (HIPEs) have gained tremendous\nattention in diverse fields, but their mechanism in the emulsification process\nremains elusive. In this article, HIPEs were stabilized directly by food-grade\nproteins, depending on a self-organized process featuring a fluid\nlaminarization. We elucidated that the emulsification with the rotor-stator\nmixer is a typical non-equilibrium process. The crucial factor for the process\nis related to the irreversible energy dissipation, while the internal phase\nvolume fraction is the threshold determining the laminarization. The feasible\nexplanation speculated that the transition corresponds to the dissipative\nstructure, i.e., compressive droplets, arising from the spatiotemporal\nself-organization, to dissipate the turbulent kinetic energy. We found a new\nparadigm of dissipative structure, comprehending such structure in the HIPEs\nemulsification process, which is expected to pave the way for its\nindustrial-scale production with the virtue of low-cost proteins.",
        "positive": "Phase equilibria in the polydisperse Zwanzig model of hard rods: We study the phase behaviour of the Zwanzig model of suspensions of hard\nrods, allowing for polydispersity in the lengths of the rods. In spite of the\nsimplified nature of the model (rods are restricted to lie along one of three\northogonal axes), the results agree qualitatively with experimental\nobservations: the coexistence region broadens significantly as the\npolydispersity increases, and strong fractionation occurs, with long rods found\npreferentially in the nematic phase. These conclusions are obtained from an\nanalysis of the exact phase equilibrium equations. In the second part of the\npaper, we consider the application of the recently developed ``moment free\nenergy method'' to the polydisperse Zwanzig model. Even though the model\ncontains non-conserved densities due to the orientational degrees of freedom,\nmost of the exactness statements (regarding the onset of phase coexistence,\nspinodals, and critical points) derived previously for systems with conserved\ndensities remain valid. The accuracy of the results from the moment free energy\nincreases as more and more additional moments are retained in the description.\nWe show how this increase in accuracy can be monitored without relying on\nknowledge of the exact results, and discuss an adaptive technique for choosing\nthe extra moments optimally."
    },
    {
        "anchor": "Dynamics of defects in active nematics: Defect dynamics in a thin active nematic layer is studied by asymptotic\nmatching of solutions in the defect core and the far field. The analysis is\nfacilitated by the correspondence between the 2D nematic and complex scalar\nfield models. Self-propulsion and topological interactions are identified as\nthe primary drivers of the defect motion, surpassing the influence of both\npassive backflow and active flow induced by other defects.",
        "positive": "Pseudochemotaxis in inhomogeneous active Brownian systems: We study dynamical properties of confined, self-propelled Brownian particles\nin an inhomogeneous activity profile. Using Brownian dynamics simulations, we\ncalculate the probability to reach a fixed target and the mean first passage\ntime to the target of an active particle. We show that both these quantities\nare strongly influenced by the inhomogeneous activity. When the activity is\ndistributed such that high-activity zone is located between the target and the\nstarting location, the target finding probability is increased and the passage\ntime is decreased in comparison to a uniformly active system. Moreover, for a\ncontinuously distributed profile, the activity gradient results in a drift of\nactive particle up the gradient bearing resemblance to chemotaxis. Integrating\nout the orientational degrees of freedom, we derive an approximate\nFokker-Planck equation and show that the theoretical predictions are in very\ngood agreement with the Brownian dynamics simulations."
    },
    {
        "anchor": "Linking scalar elastodynamics and non-Hermitian quantum mechanics: Recent years have seen a fascinating pollination of ideas from quantum\ntheories to elastodynamics---a theory that phenomenologically describes the\ntime-dependent macroscopic response of materials. Here, we open route to\ntransfer additional tools from non-Hermitian quantum mechanics. We begin by\nidentifying the differences and similarities between the one-dimensional\nelastodynamics equation and the time-independent Schrodinger equation, and\nfinding the condition under which the two are equivalent. Subsequently, we\ndemonstrate the application of the non-Hermitian perturbation theory to\ndetermine the response of elastic systems; calculation of leaky modes and\nenergy decay rate in heterogenous solids with open boundaries using a quantum\nmechanics approach; and construction of degeneracies in the spectrum of these\nassemblies. The latter result is of technological importance, as it introduces\nan approach to harness extraordinary wave phenomena associated with\nnon-Hermitian degeneracies for practical devices, by designing them in simple\nelastic systems. As an example of such application, we demonstrate how an\nassembly of elastic slabs that is designed with two degenerate shear states\naccording to our scheme, can be used for mass sensing with enhanced sensitivity\nby exploiting the unique topology near the exceptional point of degeneracy.",
        "positive": "Correlation lengths in quasi-one-dimensional systems via transfer\n  matrices: Using transfer matrices up to next-nearest-neighbour (NNN) interactions, we\nexamine the structural correlations of quasi-one-dimensional systems of hard\ndisks confined by two parallel lines and hard spheres confined in cylinders.\nSimulations have shown that the non-monotonic and non-smooth growth of the\ncorrelation length in these systems accompanies structural crossovers (Fu et\nal., Soft Matter, 2017, 13, 3296). Here, we identify the theoretical basis for\nthese behaviour. In particular, we associate kinks in the growth of correlation\nlengths with eigenvalue crossing and splitting. Understanding the origin of\nsuch structural crossovers answers questions raised by earlier studies, and\nthus bridges the gap between theory and simulations for these reference models."
    },
    {
        "anchor": "Thermotropic Orientational Order of Discotic Liquid Crystals in\n  Nanochannels: An Optical Polarimetry Study and a Landau-de Gennes Analysis: Optical polarimetry measurements of the orientational order of a discotic\nliquid crystal based on a pyrene derivative and confined in parallel-aligned\nnanochannels of monolithic mesoporous alumina, silica, and silicon as a\nfunction of temperature, channel radius (3 - 22 nm) and surface chemistry\nreveal a competition of radial and axial columnar order. The evolution of the\norientational order parameter of the confined systems is continuous, in\ncontrast to the discontinuous transition in the bulk. For channel radii larger\nthan 10 nm we suggest several, alternative defect structures, which are\ncompatible both with the optical experiments on the collective molecular\norientation presented here and with a translational, radial columnar order\nreported in previous diffraction studies. For smaller channel radii our\nobservations can semi-quantitatively be described by a Landau-de Gennes model\nwith a nematic shell of radially ordered columns (affected by elastic splay\ndeformations) that coexists with an orientationally disordered, isotropic core.\nFor these structures, the cylindrical phase boundaries are predicted to move\nfrom the channel walls to the channel centres upon cooling, and vice-versa upon\nheating, in accord with the pronounced cooling/heating hystereses observed and\nthe scaling behavior of the transition temperatures with channel diameter. The\nabsence of experimental hints of a paranematic state is consistent with a\nbiquadratic coupling of the splay deformations to the order parameter.",
        "positive": "Controlling Shear Jamming in Dense Suspensions via the Particle Aspect\n  Ratio: Dense suspension of particles in a liquid exhibit rich, non-Newtonian\nbehaviors such as shear thickening and shear jamming. Shear thickening is known\nto be enhanced by increasing the particles' frictional interactions and also by\nmaking their shape more anisotropic. For shear jamming, however, only the role\nof interparticle friction has been investigated, while the effect of changing\nparticle shape has so far not been studied systematically. To address this we\nhere synthesize smooth silica particles and design the particle surface\nchemistry to generate strong frictional interactions such that dense, aqueous\nsuspensions of spheres exhibit pronounced shear jamming. We then vary particle\naspect ratio from $\\Gamma$=1 (spheres) to $\\Gamma$=11 (slender rods), and\nperform rheological measurements to determine the effect of particle anisotropy\non the onset of shear jamming and its precursor, discontinuous shear\nthickening. Keeping the frictional interactions fixed, we find that increasing\naspect ratio significantly reduces $\\phi_m$, the minimum particle packing\nfraction at which shear jamming can be observed, to values as low $\\phi_m=33\\%$\nfor $\\Gamma$=11. The ability to independently control particle interactions due\nto friction and shape anisotropy yields fundamental insights about the\nthickening and jamming capabilities of suspensions and provides a framework to\nrationally design shear jamming characteristics."
    },
    {
        "anchor": "Heterogeneous dynamics and its length scale in simple ionic liquid\n  models: A computational study: We numerically investigate the dynamic heterogeneity and its length scale\nfound in the coarse-grained ionic liquid model systems. In our ionic liquid\nmodel systems, cations are modeled as dimers with positive charge, while anions\nare modeled as monomers with negative charge, respectively. To study the effect\nof the charge distributions on the cations, two ionic liquid models with\ndifferent charge distributions are used and the model with neutral charge is\nalso considered as a counterpart. To reveal the heterogeneous dynamics in the\nmodel systems, we examine spatial distributions of displacement and time\ndistributions of exchange and persistence times. All the models show\nsignificant increase of the dynamic heterogeneity as the temperature is\nlowered. The dynamic heterogeneity is quantified via the well-known four-point\nsusceptibility which measures the fluctuation of a time correlation function.\nThe dynamic correlation length is calculated by fitting the dynamic structure\nfactor, S4(k,t), with Ornstein-Zernike form at the time scale at which the\ndynamic heterogeneity reaches the maximum value. Obtained time and length\nscales exhibit a power law relation at the low temperatures, similar to various\nsupercooled liquid models. Especially, the charged model systems show unusual\ncrossover behaviors which are not observed in the uncharged model system. We\nascribe the crossover behavior to the enhanced cage effect caused by charges on\nthe particles.",
        "positive": "Tumbling of polymers in semidilute solution under shear flow: The tumbling dynamics of individual polymers in semidilute solution is\nstudied by large-scale non-equilibrium mesoscale hydrodynamic simulations. We\nfind that the tumbling time is equal to the non-equilibrium relaxation time of\nthe polymer end-to-end distance along the flow direction and strongly depends\non concentration. In addition, the normalized tumbling frequency as well as the\nwidths of the alignment distribution functions for a given\nconcentration-dependent Weissenberg number exhibit a weak concentration\ndependence in the cross-over regime from a dilute to a semidilute solution. For\nsemidilute solutions a universal behavior is obtained. This is a consequence of\nscreening of hydrodynamic interactions at polymer concentrations exceeding the\noverlap concentration."
    },
    {
        "anchor": "Comparison of structure making/breaking properties of alkali metal ions\n  Na+, K+ and Cs+ in water: The alkali metal ions in aqueous electrolyte solutions have strong influence\non the surrounding network structure of water formed through hydrogen bonds.\nThe extent of ionic perturbation to the structure of water depends on the\nnature of individual ions and the solute concentration. Experimental techniques\nlike Neutron diffraction, X-ray diffraction, Raman spectroscopy, isotopic\nsubstitution study, viscosity measurements and related theoretical or\nsimulation studies are used to understand the characteristics features of the\nstructural changes in these solutions. Recent ultrasonic studies on aqueous\nsolutions of NaCl, KCl and CsCl show anomalous changes in the variation of\nvelocity (v) with increase in concentration (c) from very dilute to saturation\nlimit. The experimental observations and theoretical or simulation studies\navailable in the literature are considered to make a comparative study on the\nstructure making/breaking properties of Na+, K+ and Cs+ ions in water and\nconsequent effect in ultrasonic velocity change.",
        "positive": "Micellar Crystals in Solution from Molecular Dynamics Simulations: Polymers with both soluble and insoluble blocks typically self-assemble into\nmicelles, aggregates of a finite number of polymers where the soluble blocks\nshield the insoluble ones from contact with the solvent. Upon increasing\nconcentration, these micelles often form gels that exhibit crystalline order in\nmany systems. In this paper, we present a study of both the dynamics and the\nequilibrium properties of micellar crystals of triblock polymers using\nmolecular dynamics simulations. Our results show that equilibration of single\nmicelle degrees of freedom and crystal formation occurs by polymer transfer\nbetween micelles, a process that is described by transition state theory. Near\nthe disorder (or melting) transition, bcc lattices are favored for all\ntriblocks studied. Lattices with fcc ordering are also found, but only at lower\nkinetic temperatures and for triblocks with short hydrophilic blocks. Our\nresults lead to a number of theoretical considerations and suggest a range of\nimplications to experimental systems with a particular emphasis on Pluronic\npolymers."
    },
    {
        "anchor": "Shape and Interaction Decoupling for Colloidal Pre-Assembly: Creating materials with structure that is independently controllable at a\nrange of scales requires breaking naturally occurring hierarchies. Breaking\nthese hierarchies can be achieved via the decoupling of building block\nattributes from structure during assembly. Here, we demonstrate both geometric\nand interaction decoupling in pre-assembled colloidal structures of cube-like\nparticles with rounded edges. Through computer simulations and experiments, we\nshow that compressing a small number of such cubes in spherical confinement\nresults in clusters with highly reproducible structures that can be used as\nmesoscale building blocks to form the next level of structural hierarchy. These\nclusters demonstrate geometric decoupling between particle shape and cluster\nstructure; namely, for clusters of up to nine particles, the colloidal\nsuperballs pack consistently like spheres, despite the presence of shape\nanisotropy and facets in the cubic-like particles. We confirm that cluster\nstructure is also decoupled from inter-particle interaction, showing that the\nsame structures arise from the spherical confinement of both non-magnetic and\nmagnetic colloidal cubes with strong dipolar interactions. To highlight the\npotential of these superball clusters for hierarchical assembly, we\ndemonstrate, using computer simulations, that clusters of six to nine particles\ncan self-assemble into high-order structures that differ from those of\nsimilarly shaped particles without pre-assembly. These results demonstrate\ndecoupling for anisotropic building blocks that can be further exploited for\nhierarchical materials development.",
        "positive": "Scaling of phononic transport with connectivity in amorphous solids: The effect of coordination on transport is investigated theoretically using\nrandom networks of springs as model systems. An effective medium approximation\nis made to compute the density of states of the vibrational modes, their energy\ndiffusivity (a spectral measure of transport) and their spatial correlations as\nthe network coordination $z$ is varied. Critical behaviors are obtained as\n$z\\to z_c$ where these networks lose rigidity. A sharp cross-over from a regime\nwhere modes are plane-wave-like toward a regime of extended but\nstrongly-scattered modes occurs at some frequency $\\omega^*\\sim z-z_c$, which\ndoes not correspond to the Ioffe-Regel criterion. Above $\\omega^*$ both the\ndensity of states and the diffusivity are nearly constant. These results agree\nremarkably with recent numerical observations of repulsive particles near the\njamming threshold \\cite{ning}. The analysis further predicts that the length\nscale characterizing the correlation of displacements of the scattered modes\ndecays as $1/\\sqrt{\\omega}$ with frequency, whereas for $\\omega<<\\omega^*$\nRayleigh scattering is found with a scattering length $l_s\\sim\n(z-z_c)^3/\\omega^4$. It is argued that this description applies to silica glass\nwhere it compares well with thermal conductivity data, and to transverse\nultrasound propagation in granular matter."
    },
    {
        "anchor": "Lattice Boltzmann simulation of mixtures with multicomponent van der\n  Waals equation of state: We developed a general framework for simulating multicomponent and multiphase\nsystems using the lattice Boltzmann framework. Despite the fact that there is\nno restriction on the number of components in principle, in this article we\nfocus an application to two-component mixtures, but we also demonstrate that\nthe algorighm works for larger numbers of components. To validate our algorithm\nwe separately minimized this underlying free energy to generate theoretical\nphase diagrams for mixtures of fluids with a van der Waals-like free energy.\nAll the theoretical phase diagrams are well recovered by our lattice Boltzmann\nmethod.",
        "positive": "Criterion for fingering instabilities in colloidal gels: We sandwich a colloidal gel between two parallel plates and induce a radial\nflow by lifting the upper plate at a constant velocity. Two distinct scenarios\nresult from such a tensile test: ($i$) stable flows during which the gel\nundergoes a tensile deformation without yielding, and ($ii$) unstable flows\ncharacterized by the radial growth of air fingers into the gel. We show that\nthe unstable regime occurs beyond a critical energy input, independent of the\ngel's macroscopic yield stress. This implies a local fluidization of the gel at\nthe tip of the growing fingers and results in the most unstable wavelength of\nthe patterns exhibiting the characteristic scalings of the classical viscous\nfingering instability. Our work provides a quantitative criterion for the onset\nof fingering in colloidal gels based on a local shear-induced yielding, in\nagreement with the delayed failure framework."
    },
    {
        "anchor": "The metric description of viscoelasticity and instabilities in\n  viscoelastic solids: Many manmade and naturally occurring materials form viscoelastic solids. The\nincreasing use of biologically inspired elastomeric material and the extreme\nmechanical response these elastomers offer drive the need for a better, more\nintuitive and quantitative understanding of the mechanical response of such\ncontinua. This is in particular important in determining the stability of\nviscoelastic structure over time where in lieu of robust rules we often must\nresort to simulations. In this work we put forward a metric description of\nviscoelasticity in which the continua is characterized by temporally evolving\nreference lengths quantified by a rest reference metric. This rest reference\nmetric serves as a state variable describing the result of the viscoelastic\nflow in the system, and allows us to provide robust claims regarding stability\nof incompressible isotropic viscoelastic media. We demonstrate these claims for\na simple bistable systems of three standard-linear-solid spring dashpot\nassemblies where the predicted rules can be verified by explicit calculations,\nand also show quantitative agreement with recent experiments in viscoelastic\nsilicone rubber shells that display delayed stability loss.",
        "positive": "Polydisperse polymer brushes: internal structure, critical behavior, and\n  interaction with flow: We study the effect of polydispersity on the structure of polymer brushes by\nanalytical theory, a numerical self-consistent field approach, and Monte Carlo\nsimulations. The polydispersity is represented by the Schulz-Zimm chain-length\ndistribution. We specifically focus on three different polydispersities\nrepresenting sharp, moderate and extremely wide chain length distributions and\nderive explicit analytical expressions for the chain end distributions in these\nbrushes. The results are in very good agreement with numerical data obtained\nwith self-consistent field calculations and Monte Carlo simulations. With\nincreasing polydispersity, the brush density profile changes from convex to\nconcave, and for given average chain length $N_n$ and grafting density\n$\\sigma$, the brush height $H$ is found to scale as\n$(H/H_{\\mathrm{mono}}-1)\\propto(N_w/N_n-1)^{1/2}$ over a wide range of\npolydispersity indices $N_w/N_n$ (here $H_{\\mathrm{mono}}$ is the height of the\ncorresponding monodisperse brush. Chain end fluctuations are found to be\nstrongly suppressed already at very small polydispersity. Based on this\nobservation, we introduce the concept of the brush as a near-critical system\nwith two parameters (scaling variables), $(N_{n}\\sigma^{2/3})^{-1}$ and\n$(N_w/N_n-1)^{1/2}$, controlling the distance from the critical point. This\napproach provides a good description of the simulation data. Finally we study\nthe hydrodynamic penetration length $l_\\mathrm{p}$ for brush-coated surfaces in\nflow. We find that it generally increases with polydispersity. The scaling\nbehavior crosses over from $l_\\mathrm{p}\\sim N_\\mathrm{n}^{1/2}\\sigma^{-1/6}$\nfor monodisperse and weakly polydisperse brushes to $l_\\mathrm{p}\\sim\nN_{n}^{2/3}$ for strongly polydisperse brushes."
    },
    {
        "anchor": "Rheology of colloidal microphases in a model with competing interactions: We study the rheological properties of colloidal microphases in two\ndimensions simulating a model of colloidal particles with competing\ninteractions. Due to the competition between short-range attraction and\nlong-range repulsion, as a function of the density the model exhibits a variety\nof microphases such as clusters, stripes or crystals with bubbles. We prepare\nthe system in a confined microphase employing Monte-Carlo simulations and then\nquench the system at T=0. The resulting configurations are then sheared by\napplying a drag force profile. We integrate numerically the equation of motion\nfor the particles and analyze the dynamics as a function of the density and the\napplied strain rate. We measure the stress-strain curves and characterize the\nyielding of the colloidal microphases. The results depend on the type of\nmicrophase: (i) clusters are easily sheared along layers and the relative\nmotion is assisted by rotations. (ii) Stripes shear easily when they are\nparallel to the flow and tend to jam when are perpendicular to it. Under a\nsufficiently strong shear rate perpendicular stripes orient in the flow\ndirection. (iii) Crystals with bubbles yield by fracturing along the bubbles\nand eventually forming stripes. We discuss the role of dislocations, emitted by\nthe bubbles, in the yielding process.",
        "positive": "Correlation between Macroscopic and Microscopic Relaxation Dynamics of\n  Water: Evidence for Two Liquid Forms: Water is vital for life, and without it biomolecules and cells cannot\nmaintain their structures and functions. The remarkable properties of water\noriginate from its ability to form hydrogen-bonding networks and dynamics,\nwhich the connectivity constantly alters because of the orientation rotation of\nindividual water molecules. Experimental investigation of the dynamics of\nwater, however, has proven challenging due to the strong absorption of water at\nterahertz frequencies. In response, by employing a high-precision terahertz\nspectrometer, we have measured and characterized the terahertz dielectric\nresponse of water from supercooled liquid to near the boiling point to explore\nthe motions. The response reveals dynamic relaxation processes corresponding to\nthe collective orientation, single-molecule rotation, and structural\nrearrangements resulting from breaking and reforming hydrogen bonds in water.\nWe have observed the direct relationship between the macroscopic and\nmicroscopic relaxation dynamics of water, and the results have provided\nevidence of two liquid forms in water with different transition temperatures\nand thermal activation energies. The results reported here thus provide an\nunprecedented opportunity to directly test microscopic computational models of\nwater dynamics."
    },
    {
        "anchor": "The very long range nature of capillary interactions in liquid films: Micron-sized objects confined in thin liquid films interact through forces\nmediated by the deformed liquid-air interface. This capillary interactions\nprovide a powerful driving mechanism for the self-assembly of ordered\nstructures such as photonic materials or protein crystals. Direct probing of\ncapillary interactions requires a controlled force field to independently\nmanipulate small objects while avoiding any physical contact with the\ninterface. We demonstrate how optical micro-manipulation allows the direct\nmeasurement of capillary interactions between two micron sized spheres in a\nfree standing liquid film. The force falls off as an inverse power law in\nparticles separation. We derive and validate an explicit expression for this\nexponent whose magnitude is mainly governed by particles size. For micron-sized\nobjects we found an exponent close to, but smaller than one, making capillary\ninteractions a unique example of strong and very long ranged forces in the\nmesoscopic world.",
        "positive": "Adsorption of melting deoxyribonucleic acid: The melting of a homopolymer double-stranded (ds) deoxyribonucleic acid (DNA)\nin the dilute limit is studied numerically in the presence of an attractive and\nimpenetrable surface on a simple cubic lattice. The two strands of the DNA are\nmodeled using two self-avoiding walks, capable of interacting at complementary\nsites, thereby mimicking the base pairing. The impenetrable surface is modeled\nby restricting the DNA configurations at the $z\\geq 0$ plane, with attractive\ninteractions for monomers at $z=0$. Further, we consider two variants for $z=0$\noccupations by ds segments, where one or two surface interactions are counted.\nThis consideration has significant consequences, to the extent of changing the\nstability of the bound phase in the adsorbed state. Interestingly, adsorption\nchanges from critical to first-order with a modified exponent on coinciding\nwith the melting transition. For simulations, we use the pruned and enriched\nRosenbluth algorithm."
    },
    {
        "anchor": "Comment on Geometrical Control of Active Turbulence in Curved\n  Topographies: In the recent letter Pearce et. al. Phys. Rev. Lett. 122, 168002 (2019) the\nauthors investigate the turbulent dynamics of a two-dimensional active nematic\nliquid crystal which is constrained to the surface of a torus. The underlying\nmodel combines an incompressible surface Navier-Stokes equation with friction\nand active forcing with a surface Landau-de Gennes model for nematic liquid\ncrystals. To numerically solve the surface Navier-Stokes equation a\nvorticity-stream function approach is considered. This approach is not\nappropriate on surfaces that are not simply connected - such as the considered\ntorus - due to non-trivial harmonic vector fields. We will explain the\nunderlying situation and provide details and examples to rebut the\nargumentation in Pearce et. al. Phys. Rev. Lett. 122, 168002 (2019).",
        "positive": "Thermodynamic stability versus Kinetic Accessibility: Pareto Fronts for\n  Programmable Self-Assembly: A challenge in designing self-assembling building blocks is to ensure the\ntarget state is both thermodynamically stable and kinetically accessible. These\ntwo objectives are known to be typically in competition, but it is not known\nhow to simultaneously optimize them. We consider this problem through the lens\nof multi-objective optimization theory: we develop a genetic algorithm to\ncompute the Pareto fronts characterizing the tradeoff between equilibrium\nprobability and folding rate, for a model system of small polymers of colloids\nwith tunable short-ranged interaction energies. We use a coarse-grained model\nfor the particles' dynamics that allows us to efficiently search over\nparameters, for systems small enough to be enumerated. For most target states\nthere is a tradeoff when the number of types of particles is small, with\nmedium-weak bonds favouring fast folding, and strong bonds favouring high\nequilibrium probability. The tradeoff disappears when the number of particle\ntypes reaches a value $m_*$, that is usually much less than the total number of\nparticles. This general approach of computing Pareto fronts allows one to\nidentify the minimum number of design parameters to avoid a\nthermodynamic-kinetic tradeoff. However, we argue, by contrasting our\ncoarse-grained model's predictions with those of Brownian dynamics simulations,\nthat particles with short-ranged isotropic interactions should generically have\na tradeoff, and avoiding it in larger systems will require\norientation-dependent interactions."
    },
    {
        "anchor": "Effect of particle deformability on shear thinning in a 3D channel: Soft particles suspended in fluids flowing through microchannels are often\nencountered in biological flows such as cells in vessels. They can deform under\nflow or when subject to mechanical stresses as they interact with themselves.\nDeformability adds distinct characteristics to the nature of the flow of these\nparticles. We simulate deformable particles suspended in a fluid at a high\nvolume fraction flowing through a 3D wetting channel. We find a discontinuous\nshear thinning transition, which depends on the particle deformability. The\ncapillary number is the main parameter that controls the transition. We also\nnotice significant differences in the velocity profiles when compared to their\n2D counterpart. To obtain these results, we improved and extended to 3D a\nmulticomponent Lattice Boltzmann method which prevents the coalescence between\nthe droplets.",
        "positive": "Asymptotically Improved Convergence of Optimized Perturbation Theory in\n  the Bose-Einstein Condensation Problem: We investigate the convergence properties of optimized perturbation theory,\nor linear $\\delta$ expansion (LDE), within the context of finite temperature\nphase transitions. Our results prove the reliability of these methods, recently\nemployed in the determination of the critical temperature T_c for a system of\nweakly interacting homogeneous dilute Bose gas. We carry out the explicit LDE\noptimized calculations and also the infrared analysis of the relevant\nquantities involved in the determination of $T_c$ in the large-N limit, when\nthe relevant effective static action describing the system is extended to O(N)\nsymmetry. Then, using an efficient resummation method, we show how the LDE can\nexactly reproduce the known large-N result for $T_c$ already at the first\nnon-trivial order. Next, we consider the finite N=2 case where, using similar\nresummation techniques, we improve the analytical results for the\nnonperturbative terms involved in the expression for the critical temperature\nallowing comparison with recent Monte Carlo estimates of them. To illustrate\nthe method we have considered a simple geometric series showing how the\nprocedure as a whole works consistently in a general case."
    },
    {
        "anchor": "Solution of Disordered Microphases in the Bethe approximation: The periodic microphases that self-assemble in systems with competing\nshort-range attractive and long-range repulsive interactions are structurally\nboth rich and elegant. Significant theoretical and computational efforts have\nthus been dedicated to untangling their properties. By contrast, disordered\nmicrophases, which are structurally just as rich but nowhere near as elegant,\nhave not been as carefully considered. Part of the difficulty is that simple\nmean-field descriptions make a homogeneity assumption that washes away all of\ntheir structural features. Here, we study disordered microphases by exactly\nsolving a SALR model on the Bethe lattice. By sidestepping the homogenization\nassumption, this treatment recapitulates many of the key structural regimes of\ndisordered microphases, including particle and void cluster fluids as well as\ngelation. This analysis also provides physical insight into the relationship\nbetween various structural and thermal observables, between criticality and\nphysical percolation, as well as between glassiness and microphase ordering.",
        "positive": "Magnetic tubules: Dispersion of tubules made of diacetylenic phospholipids (DC 8,9 PC), in\naqueous colloidal dispersions of magnetic nanoparticles is studied as a\nfunction of the sign of particles surface charges. In every case the\ntubule-vesicle transition temperature is decreased by the presence of the\nmagnetic nanoparticles. Electrophoresis experiments on the tubules in pure\nwater permits to conclude on a negative apparent surface charge. We study the\nmagnetic response of the system to a static or stationary rotating field and to\na magnetic field gradient. These experiments reveal an excess or a lack of\nmagnetic permeability between tubules and the surrounding medium. Electron\nmicroscopy confirms these results showing an electrostatic interaction between\nthe phospholipidic bilayer and the magnetic particles."
    },
    {
        "anchor": "From discrete particles to continuum fields near a boundary: An expression for the stress tensor near an external boundary of a discrete\nmechanical system is derived explicitly in terms of the constituents' degrees\nof freedom and interaction forces. Starting point is the exact and general\ncoarse graining formulation presented by Goldhirsch in [I. Goldhirsch, Gran.\nMat., 12(3):239-252, 2010], which is consistent with the continuum equations\neverywhere but does not account for boundaries. Our extension accounts for the\nboundary interaction forces in a self-consistent way and thus allows the\nconstruction of continuous stress fields that obey the macroscopic conservation\nlaws even within one coarse-graining width of the boundary.\n  The resolution and shape of the coarse-graining function used in the\nformulation can be chosen freely, such that both microscopic and macroscopic\neffects can be studied. The method does not require temporal averaging and thus\ncan be used to investigate time-dependent flows as well as static and steady\nsituations. Finally, the fore-mentioned continuous field can be used to define\n'fuzzy' (highly rough) boundaries. Two discrete particle method simulations are\npresented in which the novel boundary treatment is exemplified, including a\nchute flow over a base with roughness greater than a particle diameter.",
        "positive": "Heteropolymer translocation through nanopores: We investigate the translocation dynamics of heteropolymers driven through a\nnanopore using a constant temperature Langevin thermostat. Specifically, we\nconsider heteropolymers consisting of two types of monomers labeled A and B,\nwhich are distinguished by the magnitude of the driving force that they\nexperience inside the pore. From a series of studies on polymers with sequences\nAnBn+m we identify both universal as well as sequence specific properties of\nthe translocating chains. We find that the scaling of the average translocation\ntime as a function of the chain length N remains unaffected by the\nheterogeneity, while the residence time of each bead is a strong function of\nthe sequence for short repeat units. We further discover that for a symmetric\nheteropolymer AnBn of fixed length, the pattern exhibited by the residence time\nof the individual monomer has striking similarity with an interference pattern\nfor an optical grating with N/(2n) slits. These results are relevant for\ndesigning nanopore based sequencing techniques."
    },
    {
        "anchor": "Ordering kinetics in active polar fluid: We model the active polar fluid as a collection of orientable objects\nsupplied with active stresses and momentum damping coming from the viscosity of\nbulk fluid medium. The growth kinetics of local orientation field is studied.\nThe effect of active fluid is contractile or extensile depending upon the sign\nof the active stress. We explore the growth kinetics for different activities.\nWe observe that for both extensile and contractile cases the growth is altered\nby a prefactor when compared to the equilibrium Model A. We find that the\nextensile fluid enhances the domain growth whereas the contractile fluid\nsupresses it. The asymptotic growth becomes pure algebraic for large magnitudes\nof activity. We also find that the domain morphology remains unchanged due to\nactivity and system shows the good dynamic scaling for all activities. Our\nstudy provides the understanding of ordering kinetics in active polar gel.",
        "positive": "Compression Instabilities of Tissues with Localized Strain Softening: The stress-strain relationship of biological soft tissues affected by\nMarfan's syndrome is believed to be non-convex. More specifically, Haughton and\nMerodio recently proposed a strain-energy density leading to localized strain\nsoftening, in order to model the unusual mechanical behavior of these\nisotropic, incompressible tissues. Here we investigate how this choice of\nstrain energy affects the results of some instabilities studies, such as those\nconcerned with the compression of infinite and semi-infinite solids, slabs, and\ncylinders, or with the bending of blocks, and draw comparisons with known\nresults established previously for the case of a classical neo-Hookean solid.\nWe find that the localized strain softening effect leads to early instability\nonly when instability occurs at severe compression ratios for neo-Hookean\nsolids, as is the case for bulk, surface, and bending instabilities."
    },
    {
        "anchor": "Shapes of pored membranes: We study the shapes of pored membranes within the framework of the Helfrich\ntheory under the constraints of fixed area and pore size. We show that the mean\ncurvature term leads to a budding- like structure, while the Gaussian curvature\nterm tends to flatten the membrane near the pore; this is corroborated by\nsimulation. We propose a scheme to deduce the ratio of the Gaussian rigidity to\nthe bending rigidity simply by observing the shape of the pored membrane. This\nratio is usually difficult to measure experimentally. In addition, we briefly\ndiscuss the stability of a pore by relaxing the constraint of a fixed pore size\nand adding the line tension. Finally, the flattening effect due to the Gaussian\ncurvature as found in studying pored membranes is extended to two-component\nmembranes. We find that sufficiently high contrast between the components'\nGaussian rigidities leads to budding which is distinct from that due to the\nline tension.",
        "positive": "Emerging mesoscale flows and chaotic advection in dense active matter: We study two models of overdamped self-propelled disks in two dimensions,\nwith and without aligning interactions. Active mesoscale flows leading to\nchaotic advection emerge in both models in the homogeneous dense fluid away\nfrom dynamical arrest, forming streams and vortices reminiscent of multiscale\nflow patterns in turbulence. We show that the characteristics of these flows do\nnot depend on the specific details of the active fluids, and result from the\ncompetition between crowding effects and persistent propulsions. Our results\nsuggest that dense active fluids present a type of `active turbulence' distinct\nfrom collective flows reported in other types of active systems."
    },
    {
        "anchor": "Incorporating particle flexibility in a density functional description\n  of nematics and cholesterics: We describe a general implementation of the Fynewever-Yethiraj density\nfunctional theory (DFT) for the investigation of nematic and cholesteric\nself-assembly in arbitrary solutions of semi-flexible polymers. The basic\nassumptions of the theory are discussed in the context of other generalised\nOnsager descriptions for flexible polyatomic systems. The location of the\nisotropic-to-nematic phase transition is found to be in good agreement with\nmolecular simulations for elongated chains up to relatively high polymer\nflexibilities, although the predictions of the theory in the nematic regime\nlead to gradual underestimations of order parameters with decreasing particle\nstiffness. This shortcoming is attributed to increasing overestimations of the\nmolecular conformational entropy in higher-density phases, which may not be\neasily addressed in the formalism of DFT for realistic particle models.\nPractical consequences of these limitations are illustrated through the\napplication of DFT to systems of near-persistence-length DNA duplexes, whose\ncholesteric behaviour is found to be strongly contingent on their detailed\naccessible conformational space in concentrated solutions.",
        "positive": "Phase behavior of three-component ionic fluids: We study the phase behavior of solutions consisting of positive and negative\nions of valence z to which a third ionic species of valence Z>z is added. Using\na discretized Debye-Hueckel theory, we analyze the phase behavior of such\nsystems for different values of the ratio Z/z. We find, for Z/z>1.934, a\nthree-phase coexistence region and, for Z/z>2, a closed (reentrant) coexistence\nloop at high temperatures. We characterize the behavior of these ternary ionic\nmixtures as function of charge asymmetry and temperature, and show the complete\nphase diagrams for the experimentally relevant cases of Z/z=2 and Z/z=3,\ncorresponding to addition of divalent and trivalent ions to monovalent ionic\nfluids, respectively."
    },
    {
        "anchor": "Geometric frustration of hard-disk packings on cones: Conical surfaces pose an interesting challenge to crystal growth: a crystal\ngrowing on a cone can wrap around and meet itself at different radii. We use a\ndisk-packing algorithm to investigate how this closure constraint can\ngeometrically frustrate the growth of single crystals on cones with small\nopening angles. By varying the crystal seed orientation and cone angle, we find\nthat -- except at special commensurate cone angles -- crystals typically form a\nseam that runs along the axial direction of the cone, while near the tip, a\ndisordered particle packing forms. We show that the onset of disorder results\nfrom a finite-size effect that depends strongly on the circumference and not on\nthe seed orientation or cone angle. This finite-size effect occurs also on\ncylinders, and we present evidence that on both cylinders and cones, the defect\ndensity increases exponentially as circumference decreases. We introduce a\nsimple model for particle attachment at the seam that explains the dependence\non the circumference. Our findings suggest that the growth of single crystals\ncan become frustrated even very far from the tip when the cone has a small\nopening angle. These results may provide insights into the observed geometry of\nconical crystals in biological and materials applications.",
        "positive": "Transport in Charged Colloids Driven by Thermoelectricity: We study the thermal diffusion coefficient DT of a charged colloid in a\ntemperature gradient, and find that it is to a large extent determined by the\nthermoelectric response of the electrolyte solution. The thermally induced\nsalinity gradient leads in general to a strong increase with temperature. The\ndifference of the heat of transport of coions and counterions gives rise to a\nthermoelectric field that drives the colloid to the cold or to the warm,\ndepending on the sign of its charge. Our results provide an explanation for\nrecent experimental findings on thermophoresis in colloidal suspensions."
    },
    {
        "anchor": "Dynamical clustering of counterions on flexible polyelectrolytes: Molecular dynamics simulations are used to study the local dynamics of\ncounterion-charged polymer association at charge densities above and below the\ncounterion condensation threshold. Surprisingly, the counterions form\nweakly-interacting clusters which exhibit short range orientational order, and\nwhich decay slowly due to migration of ions across the diffuse double layer.\nThe cluster dynamics are insensitive to an applied electric field, and\nqualitatively agree with the available experimental data. The results are\nconsistent with predictions of the classical theory only over much longer time\nscales.",
        "positive": "Multicanonical Parallel Tempering: We present a novel implementation of the parallel tempering Monte Carlo\nmethod in a multicanonical ensemble. Multicanonical weights are derived by a\nself-consistent iterative process using a Boltzmann inversion of global energy\nhistograms. This procedure gives rise to a much broader overlap of\nthermodynamic-property histograms; fewer replicas are necessary in parallel\ntempering simulations, and the acceptance of trial swap moves can be made\narbitrarily high. We demonstrate the usefulness of the method in the context of\na grand-multicanonical ensemble, where we use multicanonical simulations in\nenergy space with the addition of an unmodified chemical potential term in\nparticle-number space. Several possible implementations are discussed, and the\nbest choice is presented in the context of the liquid-gas phase transition of\nthe Lennard-Jones fluid. A substantial decrease in the necessary number of\nreplicas can be achieved through the proposed method, thereby providing a\nhigher efficiency and the possibility of parallelization."
    },
    {
        "anchor": "Dynamics of Gas-Fluidized Granular Rods: We study a quasi-two-dimensional monolayer of granular rods fluidized by a\nspatially and temporally homogeneous upflow of air. By tracking the position\nand orientation of the particles, we characterize the dynamics of the system\nwith sufficient resolution to observe ballistic motion at the shortest time\nscales. Particle anisotropy gives rise to dynamical anisotropy and\nsuperdiffusive dynamics parallel to the rod's long axis, causing the parallel\nand perpendicular mean squared displacements to become diffusive on different\ntimescales. The distributions of free times and free paths between collisions\ndeviate from exponential behavior, underscoring the non-thermal character of\nthe particle motion. The dynamics show evidence of rotational-translational\ncoupling similar to that of an anisotropic Brownian particle. We model\nrotational-translation coupling in the single-particle dynamics with a modified\nLangevin model using non-thermal noise sources. This suggests a\nphenomenological approach to thinking about collections of self-propelling\nparticles in terms of enhanced memory effects.",
        "positive": "Layer-by-layer formation of oligoelectrolyte multilayers: a combined\n  experimental and computational study: For the first time, the combination of experimental preparation and results\nof fully atomistic simulations of an oligoelectrolyte multilayer (OEM) made of\npoly(diallyl dimethyl ammonium chloride)/poly(styrene sulfonate sodium salt)\n(PDADMAC/PSS) is presented. The layer-by-layer growth was carried out by\ndipping silica substrates in oligoelectrolyte solutions and was modeled by\nmeans of atomistic molecular dynamics simulations with a protocol that mimics\nthe experimental procedure up to the assembly of four layers. Measurements of\nOEM thickness, surface roughness and amount of adsorbed oligoelectrolyte chains\nobtained from both approaches are compared. A good agreement between simulated\nand experimental results was found, with some deviations due to intrinsic\nlimitations of both methods. However, the combination of information extracted\nfrom simulations to support the analysis of experimental data can overcome such\nrestrictions and improve the interpretation of experimental results. On the\nother hand, processes dominated by slower kinetics, like the destabilization of\nadsorbed layers upon equilibration with the surrounding environment, are out of\nreach for the simulation modeling approach, but they can be investigated by\nmonitoring in situ the oligoelectrolyte adsorption during the assembly process.\nThis demonstrates how the synergistic use of simulation and experiments\nimproves the knowledge of OEM properties down to the molecular scale."
    },
    {
        "anchor": "Angoricity and compactivity describe the jamming transition in soft\n  particulate matter: The application of concepts from equilibrium statistical mechanics to\nout-of-equilibrium systems has a long history of describing diverse systems\nranging from glasses to granular materials. For dissipative jammed systems--\nparticulate grains or droplets-- a key concept is to replace the energy\nensemble describing conservative systems by the volume-stress ensemble. Here,\nwe test the applicability of the volume-stress ensemble to describe the jamming\ntransition by comparing the jammed configurations obtained by dynamics with\nthose averaged over the ensemble as a probe of ergodicity. Agreement between\nboth methods suggests the idea of \"thermalization\" at a given angoricity and\ncompactivity. We elucidate the thermodynamic order of the jamming transition by\nshowing the absence of critical fluctuations in static observables like\npressure and volume. The approach allows to calculate observables such as the\nentropy, volume, pressure, coordination number and distribution of forces to\ncharacterize the scaling laws near the jamming transition from a statistical\nmechanics viewpoint.",
        "positive": "Kinetically driven helix formation during the homopolymer collapse\n  process: Using Langevin simulations, we find that simple 'generic' bead-and-spring\nhomopolymer chains in a sufficiently bad solvent spontaneously develop helical\norder during the process of collapsing from an initially stretched\nconformation. The helix formation is initiated by the unstable modes of the\nstraight chain, which drive the system towards a long-lived metastable\ntransient state. The effect is most pronounced if hydrodynamic interactions are\nscreened."
    },
    {
        "anchor": "A bi-directional low-Reynolds-number swimmer with passive elastic arms: It has been recently shown that it is possible to design simple artificial\nswimmers at low Reynoldsnumber that possess only one degree of freedom and,\nnevertheless, can overcome Purcell's celebratedscallop theorem. One of the few\nexamples is given by Montino and DeSimone, Eur. Phys. J. E, vol.38, 2015, who\nconsider the three-sphere Swimmer of Najafi and Golestanian, replacing one\nactive armwith a passive elastic spring. We further generalize this idea by\nincreasing the number of springs andshow that it is possible to invert the\nswimming direction using the frequency of the single actuatedarm.",
        "positive": "Phase Diagram of Active Brownian Spheres: Crystallization and the\n  Metastability of Motility-Induced Phase Separation: Motility-induced phase separation (MIPS), the phenomenon in which purely\nrepulsive active particles undergo a liquid-gas phase separation, is among the\nsimplest and most widely studied examples of a nonequilibrium phase transition.\nHere, we show that states of MIPS coexistence are in fact only metastable for\nthree-dimensional active Brownian particles over a very broad range of\nconditions, decaying at long times through an ordering transition we call\nactive crystallization. At an activity just above the MIPS critical point, the\nliquid-gas binodal is superseded by the crystal-fluid coexistence curve, with\nsolid, liquid, and gas all coexisting at the triple point where the two curves\nintersect. Nucleating an active crystal from a disordered fluid, however,\nrequires a rare fluctuation that exhibits the nearly close-packed density of\nthe solid phase. The corresponding barrier to crystallization is surmountable\non a feasible timescale only at high activity, and only at fluid densities near\nmaximal packing. The glassiness expected for such dense liquids at equilibrium\nis strongly mitigated by active forces, so that the lifetime of liquid-gas\ncoexistence declines steadily with increasing activity, manifesting in\nsimulations as a facile spontaneous crystallization at extremely high activity."
    },
    {
        "anchor": "Polyelectrolyte Complexation of Two Oppositely Charged Symmetric\n  Polymers: A Minimal Theory: Interplay of Coulomb interaction energy, free ion entropy, and conformational\nelasticity is a fascinating aspect in polyelectrolytes (PEs). We develop a\ntheory for complexation of two oppositely charged PEs, a process known to be\nthe precursor to the formation of complex coacervates in PE solutions, to\nexplore the underlying thermodynamics of complex formation, at low salts.\nExplicit calculation of the free energy of complexation and its components\nindicates that the entropy of free counterions and salt ions and the Coulomb\nenthalpy of bound ion-pairs dictate the equilibrium of PE complexation. This\nhelps decouple the self-consistent dependency of charge and size of the\nuncomplexed parts of the polyions, derive an analytical expression for charge,\nand evaluate the free energy components as functions of chain overlap.\nComplexation is observed to be driven by enthalpy gain at low Coulomb\nstrengths, driven by entropy gain of released counterions but opposed by\nenthalpy loss due to reduction of ion-pairs at moderate Coulomb strengths, and\nfinally prohibited by enthalpy loss at higher Coulomb strengths. Phase diagrams\nare constructed which identify the stability of fully-, partially- and\nun-complexed states as functions of electrostatic strength. Thermodynamic\npredictions from our model are in good quantitative agreement with simulations\nin literature, and may motivate simulations and experiments at higher\nelectrostatic strengths at which complexation is found to be unfavourable.",
        "positive": "Simulating the Entropic Collapse of Coarse-Grained Chromosomes: Depletion forces play a role in the compaction and de-compation of\nchromosomal material in simple cells but it remains debatable whether they are\nsufficient to account for chromosomal collapse. We present coarse-grained\nmolecular dynamics simulations, which reveal that depletion-induced attraction\nis sufficient to cause the collapse of a flexible chain of large structural\nmonomers immersed in a bath of smaller depletants. These simulations use an\nexplicit coarse-grained computational model that treats both the supercoiled\nDNA structural monomers and the smaller protein crowding agents as\ncombinatorial, truncated Lennard-Jones spheres. By presenting a simple\ntheoretical model, we quantitatively cast the action of depletants on\nsupercoiled bacterial DNA as an effective solvent quality. The rapid collapse\nof the simulated flexible chromosome at the predicted volume fraction of\ndepletants is a continous phase transition. Additional physical effects to such\nsimple chromosome models, such as enthalpic interactions between structural\nmonomers or chain rigidity, are required if the collapse is to be a first-order\nphase transition."
    },
    {
        "anchor": "Granular Character of Particle Rafts: We consider a monolayer of particles floating at a horizontal liquid-gas\ninterface -- a particle raft. Upon compressing the monolayer in a Langmuir\ntrough, the particles at first pack but ultimately the monolayer buckles out of\nthe plane. We measure the stress profile within the raft at the onset of\nbuckling and show for the first time that such systems exhibit a Janssen\neffect: the stress decays exponentially away from the compressing barriers over\na length scale that depends on the width of the trough. We find quantitative\nagreement between the rate of decay and the simple theory presented by Janssen\nand others. This demonstrates that floating particle rafts have a granular, as\nwell as elastic, character, which is neglected by current models. Finally, we\nsuggest that our experimental setup may be suitable for exploring granular\neffects in two dimensions without the complications of gravity and basal\nfriction.",
        "positive": "The role of vacancies, impurities and crystal structure in the magnetic\n  properties of TiO2: We present an ab initio study of pure and doped TiO2 in the rutile and\nanatase phases. The main purpose of this work is to determine the role played\nby different defects and different crystal structures in the appearance of\nmagnetic order. The calculations were performed for varying impurity and\nvacancy concentrations in both TiO2 structures. For Co impurities the local\nmagnetic moment remained almost independent of the concentration and\ndistribution while for Cu this is not the case, there is magnetism for low\nconcentrations that disappears for the higher ones. Impurity-impurity\ninteractions in both structures favor linear ordering of them. Magnetism in\nun-doped samples appears for certain vacancy concentrations and structural\nstrain."
    },
    {
        "anchor": "Single polymer gating of channels under a solvent gradient: We study the effect of a gradient of solvent quality on the coil-globule\ntransition for a polymer in a narrow pore. A simple self-attracting\nself-avoiding walk model of a polymer in solution shows that the variation in\nthe strength of interaction across the pore leads the system to go from one\nregime (good solvent) to the other (poor solvent) across the channel. This may\nbe thought analogous to thermophoresis, where the polymer goes from the hot\nregion to the cold region under the temperature gradient. The behavior of short\nchains is studied using exact enumeration whilst the behavior of long chains is\nstudied using transfer matrix techniques. The distribution of the monomer\ndensity across the layer suggests that a gate-like effect can be created, with\npotential applications as a sensor.",
        "positive": "Resetting mediated navigation of active Brownian searcher in a\n  homogeneous topography: Designing navigation strategies for search time optimization remains of\ninterest in various interdisciplinary branches in science. In here, we focus on\nmicroscopic self-propelled searchers namely active Brownian walkers in noisy\nand confined environment which are mediated by one such autonomous strategy\nnamely resetting. As such, resetting stops the motion and compels the walkers\nto restart from the initial configuration intermittently according to an\nexternal timer that does not require control by the walkers. In particular, the\nresetting coordinates are either quenched (fixed) or annealed (fluctuating)\nover the entire topography. Although the strategy relies upon simple rules, it\nshows a significant ramification on the search time statistics in contrast to\nthe original search. We show that the resetting driven protocols mitigate the\nperformance of these active searchers based, robustly, on the inherent search\ntime fluctuations. Notably, for the annealed condition, resetting is always\nfound to expedite the search process. These features, as well as their\napplicability to more general optimization problems starting from queuing\nsystems, computer science to living systems, make resetting based strategies\nuniversally promising."
    },
    {
        "anchor": "Topological Classification of Clusters in Condensed Phases: A methodology is developed to identify clusters in a bulk phase which are\ntopologically equivalent to certain reference clusters. The selected reference\nclusters are the Morse clusters with 13 or less atoms and the 13 atom clusters\nfound in an FCC and an HCP crystal phase, consisting of an atom and its 12\nnearest neighbours. The first step in using the method requires the bond\nnetwork of the bulk phase to be identified. The bonds may be identified in\nterms of the distance between the atom pairs or by using a modified Voronoi\ndecomposition, introduced here. We then search for all the 3, 4 and 5 membered\nshortest path rings and use these to identify some basic clusters. These basic\nclusters are then combined to identify the above mentioned Morse and crystal\nclusters. The larger Morse clusters (N>13) may be identified in terms of the\nbasic clusters and the smaller Morse clusters. This work has important\napplications in studying the energy landscape of a bulk phase. As an example,\nresults from a limited preliminary study on the hard sphere fluid phase are\npresented.",
        "positive": "Dynamics of orientational ordering in fluid membranes: We study the dynamics of orientational phase ordering in fluid membranes.\nThrough numerical simulation we find an unusually slow coarsening of\ntopological texture, which is limited by subdiffusive propagation of membrane\ncurvature. The growth of the orientational correlation length $\\xi$ obeys a\npower law $\\xi \\propto t^w$ with $w < 1/4$ in the late stage. We also discuss\ndefect profiles and correlation patterns in terms of long-range interaction\nmediated by curvature elasticity."
    },
    {
        "anchor": "Unexpected crossover dynamics of single polymer in a corrugated tube: We present molecular dynamics study of a generic (coarse-grained) model for\nsingle-polymer diffusion confined in a corrugated cylinder. For a narrow tube,\ni.e., diameter of the cylinder $\\delta < 2.3$, the axial diffusion coefficient\n$D_{||}$ scales as $D_{||} \\propto N^{-3/2}$, with chain length $N$, up to $N\n\\approx 100$ then crosses over to Rouse scaling for the larger $N$ values. The\n$N^{-3/2}$ scaling is due to the large fluctuation of the polymer chain along\nits fully stretched equilibrium conformation. The stronger scaling, namely\n$N^{-3/2}$, is not observed for an atomistically smooth tube and/or for a\ncylinder with larger diameter.",
        "positive": "Hyperelastic constitutive modeling with exponential decay and\n  application to a viscoelastic adhesive: Hyperelastic materials models are well established to describe the non-linear\nstress-strain relations of elastomers. In this paper, a polyurethane adhesive\nis considered as an exemplary material and subjected to tensile, compressive\nand shear tests. Conventional hyperelastic models are unable to capture the\nmechanical behaviour satisfyingly: If the model agrees with the test results at\nlarge strains, it underestimates the stiffness at low strains significantly. We\npropose a model extension to describe a kind of exponential decay of stiffness\nwhich bears some similarity with a specific model developed by Yeoh. The new\nhyperelastic model is coupled with linear viscoelasticity to account for the\nstrain rate dependence observed for the tested material. The model parameters\nare identified using a tensile test at a single strain rate only and a creep\ntest. Furthermore, the compressibility is determined by comparison of the\nstiffness in two butt joint tests with different aspect rations of the adhesive\nlayer. Using this parameter set the new model provides a very good prediction\nof tensile, compressive and shear tests at different strain rates."
    },
    {
        "anchor": "Structural Phases in Non-Additive Soft-Disk Mixtures: Glasses,\n  Substitutional Order, and Random Tilings: Relaxation of the additivity condition on the interaction length between\nunlike species in a binary mixture of soft disks opens up a rich variety of\nstructures in both crystal and amorphous states with an associated diverse\nrange of relaxation dynamics. We report on MD simulation studies of binary soft\ndisks with negative deviations from additivity that include evidence of\naccumulation of crystal-like structures in metastable liquids prior to\ncrystallization and the occurrence of a liquid to random-tiling transition.",
        "positive": "Dynamics and structure of an aging binary colloidal glass: We study aging in a colloidal suspension consisting of micron-sized particles\nin a liquid. This system is made glassy by increasing the particle\nconcentration. We observe samples composed of particles of two sizes, with a\nsize ratio of 1:2.1 and a volume fraction ratio 1:6, using fast laser scanning\nconfocal microscopy. This technique yields real-time, three-dimensional movies\ndeep inside the colloidal glass. Specifically, we look at how the size, motion\nand structural organization of the particles relate to the overall aging of the\nglass. Particles move in spatially heterogeneous cooperative groups. These\nmobile regions tend to be richer in small particles, and these small particles\nfacilitate the motion of nearby particles of both sizes."
    },
    {
        "anchor": "Why does pressure melt ice?: Compression shortens the O:H nonbond and lengthens the H-O bond\nsimultaneously via O:H-O Coulomb repulsion. The energy loss of the elongated\nH-O bond lowers the melting point.",
        "positive": "Strength and Cohesive Behavior of Thermoset Polymers at the Microscale:\n  A Size-Effect Study: This study investigated, experimentally and numerically, the fracturing\nbehavior of thermoset polymer structures featuring cracks and sharp u-notches.\nIt is shown that, even for cases in which the sharpness of the notch would\nsuggest otherwise, the failure behavior of cracked and pre-notched specimens is\nsubstantially different, the failure loads of the former configuration being\nabout three times lower than the latter one. To capture this interesting\nbehavior a two-scale cohesive model is proposed. The model is in excellent\nagreement with the experimental data and its predictions allow to conclude that\n(a) residual plastic stresses cannot explain the very high failure loads of\nnotched structures; (b) the strength of the polymer at the microscale can be\nfrom six to ten times larger than the values measured from conventional tests\nwhereas the fracture energy at the microscale can be about forty times lower;\n(c) the pre-notched specimens investigated in this work failed when the stress\nat the tip reached the microscale strength whereas the cracked specimens failed\nwhen the energy release rate reached the total fracture energy of the material.\nThe foregoing considerations are of utmost importance for the design of\nmicroelectronic devices or polymer matrix composites for which the main damage\nmechanisms are governed by the strength and cohesive behavior at the\nmicroscale."
    },
    {
        "anchor": "Indentation metrology of clamped, ultra-thin elastic sheets: We study the indentation of ultrathin elastic sheets clamped to the edge of a\ncircular hole. This classical setup has received considerable attention lately,\nbeing used by various experimental groups as a probe to measure the surface\nproperties and stretching modulus of thin solid films. Despite the apparent\nsimplicity of this method, the geometric nonlinearity inherent in the\nmechanical response of thin solid objects renders the analysis of the resulting\ndata a nontrivial task. Importantly, the essence of this difficulty is in the\ngeometric coupling between in-plane stress and out-of-plane deformations, and\nhence is present in the behaviour of Hookean solids even when the slope of the\ndeformed membrane remains small. Here we take a systematic approach to address\nthis problem, using the membrane limit of the F\\\"{o}ppl-von-K\\'{a}rm\\'{a}n\nequations. This approach highlights some of the dangers in the use of\napproximate formulae in the metrology of solid films, which can introduce large\nerrors; we suggest how such errors may be avoided in performing experiments and\nanalyzing the resulting data.",
        "positive": "Polymer Reptation in Disordered Media: The effect of ambient disorders and sequence heterogeneities on the reptation\nof a long polymer is studied with the aid of a disordered tube model. The\ndynamics of a random heteropolymer is found to be much slower than that of a\nhomopolymer due to collective pinning effects. The asymptotic properties belong\nto the universality class of a directed path in (1+1)-dimensional random media."
    },
    {
        "anchor": "Particle-scale structure in frozen colloidal suspensions from small\n  angle x-ray scattering: During directional solidification of the solvent in a colloidal suspension,\nthe colloidal particles segregate from the growing solid, forming\nhigh-particle-density regions with structure on a hierarchy of length scales\nranging from that of the particle-scale packing to the large-scale spacing\nbetween these regions. Previous work has concentrated mostly on the medium- to\nlarge-length scale structure, as it is the most accessible and thought to be\nmore technologically relevant. However, the packing of the colloids at the\nparticle-scale is an important component not only in theoretical descriptions\nof the segregation process, but also to the utility of freeze-cast materials\nfor new applications. Here we present the results of experiments in which we\ninvestigated this structure across a wide range of length scales using a\ncombination of small angle x-ray scattering and direct optical imaging. As\nexpected, during freezing the particles were concentrated into regions between\nice dendrites forming a microscopic pattern of high- and low-particle-density\nregions. X-ray scattering indicates that the particles in the high density\nregions were so closely packed as to be touching. However, the arrangement of\nthe particles does not conform to that predicted by standard inter-particle\npair potentials, suggesting that the particle packing induced by freezing\ndiffers from that formed during equilibrium densification processes.",
        "positive": "Why walking is easier than pointing: Hydrodynamics of dry active matter: Although human beings have known about the phenomenon of \"flocking\"- that is,\nthe coherent movement of large numbers of creatures (flocks of birds, schools\nof fish, herds of woolly mammoths, etc.)- since prehistoric times, it is only\nin the last two decades that we have begun to truly understand this phenomenon.\nIn particular, the surprising fact that a very large collection of organisms in\ntwo dimensions cannot all {\\it point} in the same direction, but can quite\neasily {\\it move} in the same direction, can now be explained. In these\nlectures, I'll review one of the principle theoretical tools that made this\npossible: hydrodynamics. My intention is both to elucidate flocking- or, to use\nthe specific technical mouthful, \"polar ordered dry active fluids\"-, and to use\nflocking as an illustration of how to use the hydrodynamic approach on new and\nunfamiliar systems."
    },
    {
        "anchor": "Polymer desorption under pulling: first order phase transition without\n  phase coexistence: We show that when a self-avoiding polymer chain is pulled off a sticky\nsurface by force applied to the end segment, it undergoes a first-order\nthermodynamic phase transition albeit without phase coexistence. This unusual\nfeature is demonstrated analytically by means of a Grand Canonical Ensemble\n(GCE) description of adsorbed macromolecules as well as by Monte Carlo\nsimulations of an off-lattice bead-spring model of a polymer chain. Theoretical\ntreatment and computer experiment can be carried out both in the constant-force\nf statistical ensemble and in the constant-height h ensemble. We find that the\nforce-assisted desorption undergoes a first-order dichotomic phase transition\nwhereby phase coexistence between adsorbed and desorbed states does not exist.\nIn the f-ensemble the order parameter (the fraction of chain contacts with the\nsurface) is characterized by huge fluctuations when the pulling force attains a\ncritical value f_D. In the h-ensemble, in contrast, fluctuations are always\nfinite at the critical height h_D. The derived analytical expressions for the\nprobability distributions of the basic structural units of an adsorbed polymer,\nsuch as loops, trains and tails, in terms of the adhesive potential and f or h,\nprovide a full description of the polymer structure and behavior upon\nforce-assisted detachment. In addition, one finds that the hitherto\ncontroversial value of the universal critical adsorption exponent \\phi depends\nessentially on the extent of interaction between the loops adsorbed chain so\nthat \\phi may vary within the limits 0.39 < \\phi < 0.59.",
        "positive": "The Effect of Explicit Polar Species on Conformational Behavior of a\n  Single Polyelectrolyte Chain: In this work we investigated the question of how the molecular nature of the\ndielectric media and the polymer-solvent dielectric mismatch affect the\ncollapse of a polyelectrolyte chain in solution by means of dissipative\nparticle dynamics simulations. First, we studied whether the explicit treatment\nof dielectric media as polar beads instead of homogeneous dielectric background\nresults in a different system behavior. We showed that the explicit treatment\nof polar beads facilitates the chain collapse, i.e. it occurs at smaller values\nof the electrostatic strength parameter values ${\\lambda}^2 \\sim\nQ^2/({\\epsilon}kT)$. We believe that the main reason for such behavior is that\nthe dielectric response is in fact a collective effect, and the \"effective\"\ndielectric permittivity is different from the bulk value when the charges are\nclose to each other and/or the density of the charges is high enough. This\nimplies that the value of ${\\lambda}$ does not have a universal meaning due to\nthe small-scale effects related to the presence of polar species; therefore,\nchanging the total unit charge $Q$ or the temperature $kT$ is not equivalent to\nchanging ${\\epsilon}$. Next, we investigated how the difference of the\ndielectric permittivities of the polymer chain and solvent affects the\ncollapse. We showed the polar chain adapts less swollen conformations in the\npolyelectrolyte regime and collapses easier compared to the case of non-polar\nchain; the possible reasons for such behavior are discussed."
    },
    {
        "anchor": "On the Limits of Analogy Between Self-Avoidance and Topology-Driven\n  Swelling of Polymer Loops: The work addresses the analogy between trivial knotting and excluded volume\nin looped polymer chains of moderate length, $N<N_0$, where the effects of\nknotting are small. A simple expression for the swelling seen in trivially\nknotted loops is described and shown to agree with simulation data. Contrast\nbetween this expression and the well known expression for excluded volume\npolymers leads to a graphical mapping of excluded volume to trivial knots,\nwhich may be useful for understanding where the analogy between the two\nphysical forms is valid. The work also includes description of a new method for\nthe computational generation of polymer loops via conditional probability.\nAlthough computationally intensive, this method generates loops without\nstatistical bias, and thus is preferable to other loop generation routines in\nthe region $N<N_0$.",
        "positive": "Tailored Morphologies in 2D Ferronematic Wells: We focus on a dilute uniform suspension of magnetic nanoparticles in a\nnematic-filled micron-sized shallow well with tangent boundary conditions, as a\nparadigm system with two coupled order parameters. This system exhibits\nspontaneous magnetization without magnetic fields. We numerically obtain the\nstable nematic and associated magnetization morphologies, induced purely by the\ngeometry, boundary conditions and the coupling between the magnetic\nnanoparticles and the host nematic medium. Our most striking observations\npertain to domain walls in the magnetization profile whose location can be\nmanipulated by the coupling and material properties, and stable interior and\nboundary nematic defects, whose location and multiplicity can be tailored by\nthe coupling too. These novel morphologies are not accessible in uncoupled\nsystems and can be used for new multistable systems with singularities and\nstable interfaces."
    },
    {
        "anchor": "Mechanism of acoustic emissions from booming sand dunes: The classical elastic mechanics shows that the fundamental frequency of a\nsand grain chain is similar to the typical frequency of acoustic emission\ngenerated by the booming dunes. The \"song of dunes\" is therefore considered to\noriginate from the resonance of grain chains occurring within a solid layer\nonly several centimeters thick.",
        "positive": "Dynamics of a microswimmer near a curved wall: guided and trapped\n  locomotions: We propose a combined analytical-numerical strategy to predict the dynamics\nand trajectory of a microswimmer next to a curved spherical obstacle. The\nmicroswimmer is actuated by a slip velocity on its surface and a uniformly\nvalid solution is provided by utilizing the Reynolds reciprocal theorem in\nconjunction with the exact hydrodynamic solution of translation/rotation of a\nsphere in an arbitrary direction next to a stationary obstacle. This approach\npermits the hydrodynamic interaction of the microswimmer and the obstacle to be\nconsistently and accurately calculated in both far and near fields. Based on\nthe analysis, it was shown that while the \"point-singularity solution\" is valid\nwhen the microswimmer is far from the obstacle, it fails to predict the correct\ndynamics when the swimmer is close to the obstacle (i.e. gap size is\napproximately twice the characteristic length of the microswimmer). Two\ndifferent paradigms for propulsion, so-called \"squirmer\" and \"phoretic\" models,\nwere examined and for each type of microswimmer, various types of trajectories\nare highlighted and discussed under which circumstances the swimmer can be\nhydrodynamically trapped or guided by the obstacle. The analysis indicates that\nit is always easier to capture a microswimmer in a closed circular orbit with a\nlarge sized obstacle ($\\sim 20$-$40$ times larger than the microswimmer size)\nas in this case the magnitude of rotational velocity can be sufficiently large\nthat the swimmer can adjust its distance and orientation vector with the\nobstacle."
    },
    {
        "anchor": "Contact mechanics with adhesion: Interfacial separation and contact area: We study the adhesive contact between elastic solids with randomly rough,\nself affine fractal surfaces. We present molecular dynamics (MD) simulation\nresults for the interfacial stress distribution and the wall-wall separation.\nWe compare the MD results for the relative contact area and the average\ninterfacial separation, with the prediction of the contact mechanics theory of\nPersson. We find good agreement between theory and the simulation results. We\napply the theory to the system studied by Benz et al. involving polymer in\ncontact with polymer, but in this case the adhesion gives only a small\nmodification of the interfacial separation as a function of the squeezing\npressure.",
        "positive": "Feedback-Control of Photoresponsive Fluid Interfaces: Photoresponsive surfactants provide a unique microfluidic driving mechanism.\nSince their molecular shapes change under illumination and thereby affect\nsurface tension of fluid interfaces, Marangoni flow along the interface occurs.\nTo describe the dynamics of the surfactant mixture at a planar interface, we\nformulate diffusion-advection-reaction equations for both surfactant densities.\nThey also include adsorption from and desorption into the neighboring fluids\nand photoisomerization by light. We then study how the interface responds when\nilluminated by spots of light. Switching on a single light spot, the density of\nthe switched surfactant spreads in time and assumes an exponentially decaying\nprofile in steady state. Simultaneously, the induced radial Marangoni flow\nreverses its flow direction from inward to outward. We use this feature to set\nup specific feedback rules, which couple the advection velocities sensed at the\nlight spots to their intensities. As a result two neighboring spots switch on\nand off alternately. Extending the feedback rule to light spots arranged on the\nvertices of regular polygons, we observe periodic switching patterns for\neven-sided polygons, where two sets of next-nearest neighbors alternate with\neach other. A triangle and pentagon also show regular oscillations, while\nheptagon and nonagon exhibit irregular oscillations due to frustration. While\nour findings are specific to the chosen set of parameters, they show how\ncomplex patterns at photoresponsive fluid interfaces emerge from simple\nfeedback coupling."
    },
    {
        "anchor": "Flexoelectret: An Electret with Tunable Flexoelectric-like Response: Because of the flexoelectric effect, dielectric materials usually polarize in\nresponse to a strain gradient. Soft materials are good candidates for\ndeveloping large strain gradient because of their good deformability. However,\nthey always suffer from lower flexoelectric coefficients compared to ceramics.\nIn this work, a flexoelectric-like effect is introduced to enhance the\neffective flexoelectricity of a polydimethylsiloxane (PDMS) bar. The\nflexoelectric-like effect is realized by depositing a layer of net charges on\nthe middle plane of the bar to form an electret. Experiments show that the\nenhancement of the flexoelectricity depends on the density of inserted net\ncharges. It is found that a charged layer with surface potential of -5723V\nresults in 100 times increase of the material's flexoelectric coefficient. We\nalso show that the enhancement is proportional to the thickness of electrets.\nThis work provides a new way of enhancing flexoelectricity in soft materials\nand further prompt the application of soft materials in electromechanical\ntransducers.",
        "positive": "Tuning effective interactions close to the critical point in colloidal\n  suspensions: We report a numerical investigation of two colloids immersed in a critical\nsolvent, with the aim of quantifying the effective colloid-colloid interaction\npotential. By turning on an attraction between the colloid and the solvent\nparticles we follow the evolution from the case in which the solvent density\nclose to the colloids changes from values smaller than the bulk to values\nlarger than the bulk. We thus effectively implement the so-called $(+,+)$ and\n$(-,-)$ boundary conditions defined in field theoretical approaches focused on\nthe description of critical Casimir forces. We find that the effective\npotential at large distances decays exponentially, with a characteristic decay\nlength compatible with the bulk critical correlation length, in full agreement\nwith theoretical predictions. We also investigate the case of $(+,-)$ boundary\ncondition, where the effective potential becomes repulsive. Our study provides\na guidance for a design of the interaction potential which can be exploited to\ncontrol the stability of colloidal systems."
    },
    {
        "anchor": "Dynamic shear jamming in dense granular suspensions under extension: Unlike dry granular materials, a dense granular suspension like cornstarch in\nwater can strongly resist extensional flows. At low extension rates, such a\nsuspension behaves like a viscous liquid, but rapid extension results in a\nresponse where stresses far exceed the predictions of lubrication hydrodynamics\nand capillarity. To understand this remarkable mechanical response, we\nexperimentally measure the normal force imparted by a large bulk of the\nsuspension on a plate moving vertically upward at a controlled velocity. We\nobserve that above a velocity threshold, the peak force increases by orders of\nmagnitude. Using fast ultrasound imaging we map out the local velocity profiles\ninside the suspension which reveal the formation of a growing jammed region\nunder rapid extension. This region interacts with the rigid boundaries of the\ncontainer through strong velocity gradients, suggesting a direct connection to\nthe recently proposed shear-jamming mechanism.",
        "positive": "Transient Shear Banding in a Simple Yield Stress Fluid: We report a large set of experimental data which demonstrates that a simple\nyield stress fluid, i.e. which does not present aging or thixotropy, exhibits\ntransient shear banding before reaching a steady state characterized by a\nhomogeneous, linear velocity profile. The duration of the transient regime\ndecreases as a power law with the applied shear rate $\\dot\\gamma$. This power\nlaw behavior, observed here in carbopol dispersions, does not depend on the gap\nwidth and on the boundary conditions for a given sample preparation. For\n$\\dot\\gamma\\lesssim 0.1$ s$^{-1}$, heterogeneous flows could be observed for as\nlong as 10$^5$ s. These local dynamics account for the ultraslow stress\nrelaxation observed at low shear rates."
    },
    {
        "anchor": "Universal Nucleation Behaviour of Sheared Systems: Using molecular simulations and a modified Classical Nucleation Theory, we\nstudy the nucleation, under flow, of a variety of liquids: different water\nmodels, Lennard-Jones and hard sphere colloids. Our approach enables us to\nanalyze a wide range of shear rates inaccessible to brute-force simulations.\nOur results reveal that the variation of the nucleation rate with shear is\nuniversal. A simplified version of the theory successfully captures the\nnon-monotonic temperature dependence of the nucleation behavior, which is shown\nto originate from the violation of the Stokes-Einstein relation.",
        "positive": "Determining phoretic mobilities with Onsager's reciprocal relations:\n  electro- and thermophoresis revisited: We use a hydrodynamic reciprocal approach to phoretic motion to derive\ngeneral expressions for the electrophoretic and thermophoretic mobility of\nweakly charged colloids in aqueous electrolyte solutions. Our approach shows\nthat phoretic motion can be understood in terms of the interfacial transport of\nthermodynamic excess quantities that arises when a colloid is kept stationary\ninside a bulk fluid flow. The obtained expressions for the mobilities are\nextensions of previously known results as they can account for different\nhydrodynamic boundary conditions at the colloidal surface, irrespective of how\nthe colloid-fluid interaction range compares to the colloidal radius."
    },
    {
        "anchor": "Martini coarse-grained model for clay-polymer nanocomposites: We have developed a coarse-grained (CG) model of a polymer-clay system\nconsisting of organically modified montmorillonite nanoclay as the nanoparticle\nin accordance with the MARTINI forcefield. We have used mechanical properties\nand cleavage free energy of clay particle to respectively parameterize bonded\nand nonbonded interaction parameters for an organically modified\nmontmorillonite (oMMT) clay particle where intergallery Na+ ions are replaced\nby tetramethylammonium (TMA) ions. The mechanical properties were determined\nfrom the slope of stress-strain curve and cleavage free energy was determined\nby allowing for full surface reconstruction corresponding to a slow equilibrium\ncleavage process. Individual dispersive and polar contributions to oMMT\ncleavage energy were used for determination of appropriate MARTINI bead types\nfor CG oMMT sheet. The self-consistency of developed MARTINIFF parameters for\nTMA-MMT-polymer system was verified by comparing estimates for select\nstructural, thermodynamic, and dynamic properties obtained in all-atomistic\nsimulations with that obtained in coarse-grained simulations. We have\ndetermined the influence of clay particle on properties of three polymer melts\n(polyethylene, polypropylene, and polystyrene) at two temperatures to establish\ntransferability of the developed parameters. We have also shown that the effect\nof clay-polymer interactions on structure-property relationships in this\nnanocomposite system is well captured by Rosenfeld's excess entropy scaling.",
        "positive": "Fluctuating motion in an active environment: We derive the fluctuation dynamics of a probe in weak coupling with a\n\"living\" medium, modeled as particles undergoing an active Ornstein-Uhlenbeck\ndynamics. Nondissipative corrections to the fluctuation-dissipation relation\nare written out explicitly in terms of time-correlations in the active medium.\nA first term changes the inertial mass of the probe, as a consequence of the\npersistence of the active medium. A second correction modifies the friction\nkernel. The resulting generalized Langevin equation benchmarks the motion\ninduced on probes immersed in active versus passive media. The derivation uses\nnonequilibrium response theory."
    },
    {
        "anchor": "Universal scaling function ansatz for finite-temperature jamming: We cast a nonzero-temperature analysis of the jamming transition into the\nframework of a scaling ansatz. We show that four distinct regimes for scaling\nexponents of thermodynamic derivatives of the free energy such as pressure,\nbulk and shear moduli, can be consolidated by introducing a universal scaling\nfunction with two branches. Both the original analysis and the scaling theory\nassume that the system always resides in a single basis in the energy\nlandscape. The two branches are separated by a line $T^*(\\Delta \\phi)$ in the\n$T-\\Delta \\phi$ plane, where $\\Delta \\phi=\\phi-\\phi_c^\\Lambda$ is the deviation\nof the packing fraction from its critical, jamming value, $\\phi_c^\\Lambda$, for\nthat basin. The branch for $T<T^*(\\Delta \\phi)$ reduces at $T=0$ to an earlier\nscaling ansatz that is restricted to $T=0$, $\\Delta \\phi \\ge 0$, while the\nbranch for $T>T^*(\\Delta \\phi)$ reproduces exponents observed for thermal hard\nspheres. In contrast to the usual scenario for critical phenomena, the two\nbranches are characterized by different exponents. We suggest that this unusual\nfeature can be resolved by the existence of a dangerous irrelevant variable\n$u$, which can appear to modify exponents if the leading $u=0$ term is\nsufficiently small in the regime described by one of the two branches of the\nscaling function.",
        "positive": "Polymer translocation into and out of an ellipsoidal cavity: Monte Carlo simulations are used to study the translocation of a polymer into\nand out of a ellipsoidal cavity through a narrow pore. We measure the polymer\nfree energy F as a function of a translocation coordinate, s, defined to be the\nnumber of bonds that have entered the cavity. To study polymer insertion, we\nconsider the case of a driving force acting on monomers inside the pore, as\nwell as monomer attraction to the cavity wall. We examine the changes to F(s)\nupon variation in the shape anisometry and volume of the cavity, the polymer\nlength, and the strength of the interactions driving the insertion. For\nathermal systems, the free energy functions are analyzed using a scaling\napproach, where we treat the confined portion of the polymer to be in the\nsemi-dilute regime. The free energy functions are used with the Fokker-Planck\nequation to measure mean translocation times, as well as translocation time\ndistributions. We find that both polymer ejection and insertion is faster for\nellipsoidal cavities than for spherical cavities. The results are in\nqualitative agreement with those of a Langevin dynamics study in the case of\nejection but not for insertion. The discrepancy is likely due to\nout-of-equilibrium conformational behaviour that is not accounted for in the FP\napproach"
    },
    {
        "anchor": "Aging in a Colloidal Glass in Creep Flow: Time-Stress Superposition: In this work, we study ageing behavior of aqueous laponite suspension, a\nmodel soft glassy material, in creep. We observe that viscoelastic behavior is\ntime dependent and is strongly influenced by the deformation field; the effect\nis known to arise due to ageing and rejuvenation. We show that irrespective of\nstrength of deformation field (shear stress) and age, when imposed time-scale\nis normalized with dominating relaxation mode of the system, universal ageing\nbehavior is obtained demonstrating time-stress superposition; the phenomena\nthat may be generic in variety of soft materials.",
        "positive": "The free-energy landscape of a mechanically bistable DNA origami: Molecular simulations using coarse-grained models allow the structure,\ndynamics and mechanics of DNA origamis to be comprehensively characterized.\nHere, we focus on the free-energy landscape of a jointed DNA origami that has\nbeen designed to exhibit two mechanically stable states and for which a\nbistable landscape has been inferred from ensembles of structures visualized by\nelectron microscopy. Surprisingly, simulations using the oxDNA model predict\nthat the defect-free origami has a single free-energy minimum. The expected\nsecond state is not stable because the hinge joints do not simply allow free\nangular motion but instead lead to increasing free-energetic penalties as the\njoint angles relevant to the second state are approached. This raises\ninteresting questions about the cause of this difference between simulations\nand experiment, such as how assembly defects might affect the ensemble of\nstructures observed experimentally."
    },
    {
        "anchor": "Mechanical unfolding of a homopolymer globule: applied force vs applied\n  deformation: We propose the quantitative mean-field theory of mechanical unfolding of a\nglobule formed by long flexible homopolymer chain collapsed in poor solvent and\nsubjected to an extensional force We show that with an increase in the applied\nforce the globule unfolds as a whole without formation of an intermediate\nstate. The value of the threshold force and the corresponding jump in the\ndistance between chain ends increase with a deterioration of the solvent\nquality and / or with an increase in the degree of polymerization. This way of\nglobule unfolding is compared with that in the D-ensemble, when the distance\nbetween chain ends is imposed.",
        "positive": "Universal Law of Coiling for a Short Elastic Strip Contacting Within a\n  Tube: We find that there exists a universal law of coiling not only for a long\nelastic strip contacting within a tube but also for a short one. Here the\nelastic strip we consider has the ratio of $2 < L/R \\le 2\\pi$ for its length\n$L$ to the tube radius $R$. By varying the ratio of $L/R$, we identify four\ntypes of deformation for such a short elastic strip, namely, two point-contact,\nthree point-contact, continuous-contact, and self-contact. With theoretical\nformulas in closed forms and experimental demonstration, these four types are\nverified for any elastic strips contacting within a tube, irrespective of\nelastic properties, strip lengths, and tube radius. Our results on coiling can\nbe readily applied to a variety of physical systems, including thin flexible\nelectronic devices, van der Waals materials in scroll shape, and DNA packaging\ninto viral capsids."
    },
    {
        "anchor": "Thin film modeling of crystal dissolution and growth in confinement: We present a continuum model describing dissolution and growth of a crystal\ncontact confined against a substrate. Diffusion and hydrodynamics in the liquid\nfilm separating the crystal and the substrate are modeled within the\nlubrication approximation. The model also accounts for the disjoining pressure\nand surface tension. Within this framework, we obtain evolution equations which\ngovern the non-equilibrium dynamics of the crystal interface. Based on this\nmodel, we explore the problem of dissolution under an external load, known as\npressure solution. We find that in steady-state, diverging (power-law)\ncrystal-surface repulsions lead to flat contacts with a monotonic increase of\nthe dissolution rate as a function of the load. Forces induced by viscous\ndissipation then surpass those due to disjoining pressure at large enough\nloads. In contrast, finite repulsions (exponential) lead to sharp pointy\ncontacts with a dissolution rate independent on the load and on the liquid\nviscosity. Ultimately, in steady-state the crystal never touches the substrate\nwhen pressed against it, independently from the nature of the crystal-surface\ninteraction due to the combined effects of viscosity and surface tension.",
        "positive": "How to Fit simply Soil Mechanics Behaviour with Incremental Modelling\n  and to Describe Drained Cyclic Behaviours: It has been proposed recently a new incremental modelling to describe the\nmechanics of soil. It is based on two parameters called the pseudo Young\nmodulus E=1/Co and the pseudo Poisson coefficient n, which both evolve during\ncompression. Evolution of n is known since it shall fit the Rowe's law of\ndilatancy, but Co has to be evaluated from experiment. In this paper we\nproposed a way to evaluate the Co variation from other mechanical modelling.\nThe way cyclic behaviour of drained sample can be modelled is also described."
    },
    {
        "anchor": "Hot Brownian Motion of thermoresponsive microgels in optical tweezers\n  shows discontinuous volume phase transition and bistability: Microgels are soft microparticles that often exhibit thermoresponsiveness and\nfeature a transformation at a critical temperature, referred to as the volume\nphase transition temperature. The question of whether this transformation\noccurs as a smooth or as a discontinuous one is still a matter of debate. This\nquestion can be addressed by studying individual microgels trapped in optical\ntweezers. For this aim, composite particles were obtained by decorating pNIPAM\nmicrogels with iron oxide nanocubes. These composites become self-heating when\nilluminated by the infrared trapping laser, featuring Hot Brownian Motion\nwithin the trap. Above a certain laser power, a single decorated microgel\nfeatures a volume phase transition that is discontinuous, while the usual\ncontinuous sigmoidal-like dependence is recovered after averaging over\ndifferent microgels. The collective sigmoidal behavior enables the application\nof a power-to-temperature calibration and provides the effective drag\ncoefficient of the self-heating microgels, thus establishing these composite\nparticles as potential micro-thermometers and micro-heaters. Moreover, the\nself-heating microgels also exhibit an unexpected and intriguing bistability\nbehavior above the critical temperature, probably due to partial collapses of\nthe microgel. These results set the stage for further studies and the\ndevelopment of applications based on the Hot Brownian Motion of soft particles.",
        "positive": "Microrheology of colloidal suspensions via Dynamic Monte Carlo\n  simulations: Understanding the rheology of colloidal suspensions is crucial in the\nformulation of a wide selection of industry-relevant products. To characterise\nthe viscoelastic behaviour of these soft materials, one can analyse the\nmicroscopic dynamics of colloidal tracers diffusing through the host fluid and\ngenerating local deformations and stresses. This technique, referred to as\nmicrorheology, links the bulk rheology of fluids to the microscopic dynamics at\nthe particle scale. If tracers are subjected to external forces, rather than\nfreely diffusing, it is called active microrheology. Motivated by the impact of\nmicrorheology in providing information on local structure in complex systems\nsuch as colloidal glasses, active matter or biological systems, we have\nextended the dynamic Monte Carlo (DMC) technique to investigate active\nmicrorheology in colloids. The original DMC framework, able to accurately\ndescribe the Brownian dynamics of colloids at equilibrium, is here reconsidered\nand expanded to describe the effects of an external force pulling a tracer\nembedded in isotropic colloidal suspensions at different densities. To this\nend, we studied the dynamics of a spherical tracer dragged by a constant\nexternal force through a bath of spherical and rod-like particles of comparable\nsize. We could extract valuable details on its effective friction coefficient,\nbeing constant at small and large values of the external force, but otherwise\ndisplaying a nonlinear behaviour that indicates the occurrence of a\nforce-thinning regime. Our DMC simulation results are in excellent quantitative\nagreement with past Langevin dynamics simulations and theoretical works for the\nbath of spherical colloids. The bath of rod-like particles is studied in the\nisotropic phase, and displays an example where DMC is more convenient than\nBrownian or Langevin dynamics, in this case in dealing with particle rotation."
    },
    {
        "anchor": "Localization and diffusion of tracer particles in viscoelastic media\n  with active force dipoles: Optical tracking in vivo experiments reveal that diffusion of particles in\nbiological cells is strongly enhanced in the presence of ATP and the\nexperimental data for animal cells could previously be reproduced within a\nphenomenological model of a gel with myosin motors acting within it [EPL 110,\n48005 (2015)]. Here, the two-fluid model of a gel is considered where active\nmacromolecules, described as force dipoles, cyclically operate both in the\nelastic and the fluid components. Through coarse-graining, effective equations\nof motions for tracer particles displaying local deformations and local fluid\nflows are derived. The equation for deformation tracers coincides with the\nearlier phenomenological model and thus confirms it. For flow tracers,\ndiffusion enhancement caused by active force dipoles in the fluid component,\nand thus due to metabolic activity, is found. The latter effect may explain why\nATP-dependent diffusion enhancement could also be observed in bacteria that\nlack molecular motors in their skeleton or when the activity of myosin motors\nwas chemically inhibited.",
        "positive": "Universal collapse of the viscosity of supercooled fluids: All liquids in nature can be supercooled to form a glass. Surprisingly,\nalthough this phenomenon has been employed for millennia, it still remains\nill-understood. Perhaps the most puzzling feature of supercooled liquids is the\ndramatic increase in their viscosity as the temperature ($T$) is lowered. This\nprecipitous rise has long posed a fundamental theoretical challenge. Numerous\napproaches currently attempt to explain this phenomenon. When present, data\ncollapse points to an underlying simplicity in various branches of science. In\nthis Letter, we report on a 16 decade data collapse of the viscosity of 45\ndifferent liquids of all known types. Specifically, the viscosity of\nsupercooled liquids scaled by their value at their respective equilibrium\nmelting temperature ($\\eta(T)/\\eta(T_{melt}))$ is, for all temperatures\n$T<T_{melt}$, a universal function of $(T_{melt} - T)/(B T)$ where $B$ is a\nconstant that does not change significantly from one liquid to another. This\nexceptionally plain behavior hints at a link between glassy dynamics and the\nconventional equilibrium melting transition in all known supercooled fluids."
    },
    {
        "anchor": "Fluid viscoelasticity triggers fast transitions of a Brownian particle\n  in a double well optical potential: Thermally activated transitions are ubiquitous in nature, occurring in\ncomplex environments which are typically conceived as ideal viscous fluids. We\nreport the first direct observations of a Brownian bead transiting between the\nwells of a bistable optical potential in a viscoelastic fluid with a single\nlong relaxation time. We precisely characterize both the potential and the\nfluid, thus enabling a neat comparison between our experimental results and a\ntheoretical model based on the generalized Langevin equation. Our findings\nreveal a drastic amplification of the transition rates compared to those in a\nNewtonian fluid, stemming from the relaxation of the fluid during the particle\ncrossing events.",
        "positive": "Unravelling Nanoconfined Films of Ionic Liquids: The confinement of an ionic liquid between charged solid surfaces is treated\nusing an exactly solvable 1D Coulomb gas model. The theory highlights the\nimportance of two dimensionless parameters: the fugacity of the ionic liquid,\nand the electrostatic interaction energy of ions at closest approach relative\nto thermal energy, in determining how the disjoining pressure exerted on the\nwalls depends on the geometrical confinement. Our theory reveals that\nthermodynamic fluctuations play a vital role in the \"squeezing out\" of charged\nlayers as the confinement is increased. The model shows good qualitative\nagreement with previous experimental data, with all parameters independently\nestimated without fitting."
    },
    {
        "anchor": "The influence of the cylindrical shape of the nucleosomes and H1 defects\n  on properties of chromatin: We present a model improving the two-angle model for interphase chromatin\n(E2A model). This model takes into account the cylindrical shape of the histone\noctamers, the H1 histones in front of the nucleosomes and the vertical distance\n$d$ between the in and outgoing DNA strands. Factoring these chromatin features\nin, one gets essential changes in the chromatin phase diagram: Not only the\nshape of the excluded-volume borderline changes but also the vertical distance\n$d$ has a dramatic influence on the forbidden area. Furthermore, we examined\nthe influence of H1 defects on the properties of the chromatin fiber. Thus we\npresent two possible strategies for chromatin compaction: The use of very dense\nstates in the phase diagram in the gaps in the excluded volume borderline or\nmissing H1 histones which can lead to very compact fibers. The chromatin fiber\nmight use both of these mechanisms to compact itself at least locally. Line\ndensities computed within the model coincident with the experimental values.",
        "positive": "Thermodynamics of active matter: Tracking dissipation across scales: The concept of entropy has been pivotal in the formulation of thermodynamics.\nFor systems driven away from thermal equilibrium, a comparable role is played\nby entropy production and dissipation. Here we provide a comprehensive picture\nhow local dissipation due to effective chemical events manifests on large\nscales in active matter. We start from a microscopic model for a single\ncatalytic particle involving explicit solute molecules and show that it\nundergoes directed motion. Leveraging stochastic thermodynamics, we calculate\nthe average entropy production rate for interacting particles. We then show how\nthe model of active Brownian particles emerges in a certain limit and we\ndetermine the entropy production rate on the level of the hydrodynamic\nequations. Our results augment the model of active Brownian particles with\nrigorous expressions for the dissipation that cannot be inferred from their\nequations of motion, and we illustrate consequences for wall aggregation and\nmotility-induced phase separation. Notably, our bottom-up approach reveals that\na naive application of the Onsager currents yields an incorrect expression for\nthe local dissipation."
    },
    {
        "anchor": "Combined density functional and Brazovskii theories for systems with\n  spontaneous inhomogeneities: The low-T part of the phase diagram in self-assembling systems is correctly\npredicted by the known versions of the density functional theory (DFT). The\nhigh-T part obtained in DFT, however, does not agree with simulations even on\nthe qualitative level. In this work a new version of the DFT is developed. The\ncontribution to the grand thermodynamic potential associated with mesoscopic\nfluctuations is explicitly taken into account. The expression for this\ncontribution is obtained by the methods known from the Brazovskii field theory.\nApart from developing the approximate expression for the grand thermodynamic\npotential that contains the fluctuation contribution and is ready for numerical\nminimization, we develop a simplified version of the theory valid for weakly\nordered phases, i.e. for the high -T part of the phase diagram. The simplified\ntheory is verified by a comparison with the results of simulations for a\nparticular version of the short-range attraction long-range repulsion (SALR)\ninteraction potential. Except from the fact that in our theory the ordered\nphases are stable at lower T than in simulations, a good agreement for the\nhigh-T part of the phase diagram is obtained for the range of density that was\nconsidered in simulations. In addition, the equation of state and\ncompressibility isotherms are presented. Finally, the physical interpretation\nof the fluctuation-contribution to the grand potential is discussed in detail.",
        "positive": "Probabilistic Phase Space Trajectory Description for Anomalous Polymer\n  Dynamics: It has been recently shown that the phase space trajectories for the\nanomalous dynamics of a tagged monomer of a polymer --- for single polymeric\nsystems such as phantom Rouse, self-avoiding Rouse, Zimm, reptation, and\ntranslocation through a narrow pore in a membrane; as well as for\nmany-polymeric system such as polymer melts in the entangled regime --- is\nrobustly described by the Generalized Langevin Equation (GLE). Here I show that\nthe probability distribution of phase space trajectories for all these\nclassical anomalous dynamics for single polymers is that of a fractional\nBrownian motion (fBm), while the dynamics for polymer melts between the\nentangled regime and the eventual diffusive regime exhibits small, but\nsystematic deviations from that of a fBm."
    },
    {
        "anchor": "Quadrupolar active stress induces exotic phases of defect motion in\n  active nematics: A wide range of living and artificial active matter exists in close contact\nwith substrates and under strong confinement, where in addition to dipolar\nactive stresses, quadrupolar active stresses can become important. Here, we\nnumerically investigate the impact of quadrupolar non-equilibrium stresses on\nthe emergent patterns of self-organisation in non-momentum conserving active\nnematics. Our results reveal that beyond having stabilising effects, the\nquadrupolar active forces can induce various modes of topological defect motion\nin active nematics. In particular, we find the emergence of both polar and\nnematic ordering of the defects, as well as new phases of self-organisation\nthat comprise topological defect chains and topological defect asters. The\nresults contribute to further understanding of emergent patterns of collective\nmotion and non-equilibrium self-organisation in active matter.",
        "positive": "V-T Theory of Self Dynamic Response in a Monatomic Liquid: A new theoretical model for self dynamic response is developed using\nVibration-Transit (V-T) theory, and is applied to liquid sodium at all\nwavevectors q from the hydrodynamic regime to the free particle limit. In this\ntheory the zeroth-order Hamiltonian describes the vibrational motion in a\nsingle random valley harmonically extended to infinity. This Hamiltonian is\ntractable, is evaluated a priori for monatomic liquids, and the same\nHamiltonian (the same set of eigenvalues and eigenvectors) is used for\nequilibrium and nonequlibrium theory. Here, for the self intermediate\nscattering function Fself(q,t) we find the vibrational contribution is in near\nperfect agreement with molecular dynamics (MD) through short and intermediate\ntimes, at all q. This is direct confirmation that normal mode vibrational\ncorrelations are present in the motion of the liquid state. The primary transit\neffect is diffusive motion of the vibrational equilibrium positions, as the\nliquid transits rapidly among random valleys. This motion is modeled as a\nstandard random walk, and the resulting theoretical Fself(q,t) is in excellent\nagreement with MD results at all q and t. In the limit for q to infinity, the\ntheory automatically exhibits the correct approach to the free-particle limit.\nAlso in the limit for q to zero, the hydrodynamic limit emerges as well. In\ncontrast to the benchmark theories of generalized hydrodynamics and mode\ncoupling, the present theory is near a priori, while achieving modestly better\naccuracy. Therefore, in our view, it constitutes an improvement over the\ntraditional theories."
    },
    {
        "anchor": "Why Microtubules run in Circles - Mechanical Hysteresis of the Tubulin\n  Lattice: The fate of every eukaryotic cell subtly relies on the exceptional mechanical\nproperties of microtubules. Despite significant efforts, understanding their\nunusual mechanics remains elusive. One persistent, unresolved mystery is the\nformation of long-lived arcs and rings, e.g. in kinesin-driven gliding assays.\nTo elucidate their physical origin we develop a model of the inner workings of\nthe microtubule's lattice, based on recent experimental evidence for a\nconformational switch of the tubulin dimer. We show that the microtubule\nlattice itself coexists in discrete polymorphic states. Curved states can be\ninduced via a mechanical hysteresis involving torques and forces typical of few\nmolecular motors acting in unison. This lattice switch renders microtubules not\nonly virtually unbreakable under typical cellular forces, but moreover provides\nthem with a tunable response integrating mechanical and chemical stimuli.",
        "positive": "Star shaped patterns caused by colloidal aggregation during the\n  spreading process of a droplet: This research found that when an acidic solution with a low surface tension\nspread on the surface of a glycerol solution mixed with milk, a star shaped\npattern was spontaneously formed on the surface in the horizontal plane during\nthe spreading process. We investigated the emergence of the star shaped pattern\nowing to an interfacial instability in experiments using glycerol solutions\nwith several viscosities and 2-methoxyethanol aqueous solutions, which are\nacidic solutions, with several concentrations. This result demonstrated that\nthe star shaped pattern emerged in the high concentration of 2-methoxyethanol.\nWe proposed a phenomenological model, based on our experimental results, which\nexplains three points as follows; the spreading of the 2-methoxyethanol aqueous\nsolution on the surface of the glycerol solution, the colloidal aggregation of\nthe milk protein colloids caused by the denaturation that occurs when mixed\nwith 2-methoxyethanol, and the accumulation of the aggregates toward the dent\nregions of the moving interface by a sweeping effect. The model reproduces the\nformation of the star shaped pattern which was similar to the experimental one.\nFurthermore, the model provided a phase diagram against the concentration of\nthe 2-methoxyethanol solution and the viscosity of the glycerol solution as\ncontrol parameters in our experiments. The phase diagram was close to that\nobtained from our experiments. The results suggest that the above three points\nare important for the formation of the star shaped pattern."
    },
    {
        "anchor": "Magnetic wire active microrheology of human respiratory mucus: Mucus is a viscoelastic gel secreted by the pulmonary epithelium in the\ntracheobronchial region of the lungs. The coordinated beating of cilia moves\nmucus upwards towards pharynx, removing inhaled pathogens and particles from\nthe airways. The efficacy of this clearance mechanism depends primarily on the\nrheological properties of mucus. Here we use magnetic wire based microrheology\nto study the viscoelastic properties of human mucus collected from human\nbronchus tubes. The response of wires between 5 and 80 microns in length to a\nrotating magnetic field is monitored by optical time-lapse microscopy and\nanalyzed using constitutive equations of rheology, including those of Maxwell\nand Kelvin-Voigt. The static shear viscosity and elastic modulus can be\ninferred from low frequency (from 0.003 to 30 rad s-1) measurements, leading to\nthe evaluation of the mucin network relaxation time. This relaxation time is\nfound to be widely distributed, from one to several hundred seconds. Mucus is\nidentified as a viscoelastic liquid with an elastic modulus of 2.5 +/- 0.5 Pa\nand a static viscosity of 100 +/- 40 Pa s. Our work shows that beyond the\nestablished spatial variations in rheological properties due to microcavities,\nmucus exhibits secondary inhomogeneities associated with the relaxation time of\nthe mucin network that may be important for its flow properties.",
        "positive": "Contributions of Repulsive and Attractive Interactions to Nematic Order: Both repulsive and attractive molecular interactions can be used to explain\nthe onset of nematic order. The object of this paper is to combine these two\nnematogenic molecular interactions in a unified theory. This attempt is not\nunprecedented; what is perhaps new is the focus on the understanding of\nnematics in the high density limit. There, the orientational probability\ndistribution is shown to exhibit a unique feature: it has compact support on\nconfiguration space. As attractive interactions are turned on, the behavior\nchanges, and at a critical attractive interaction strength, thermotropic\nbehavior of the Maier-Saupe type is attained."
    },
    {
        "anchor": "Aspects of Jamming in Two-Dimensional Frictionless Systems: In this work we provide an overview of jamming transitions in two dimensional\nsystems focusing on the limit of frictionless particle interactions in the\nabsence of thermal fluctuations. We first discuss jamming in systems with short\nrange repulsive interactions, where the onset of jamming occurs at a critical\npacking density and where certain quantities show a divergence indicative of\ncritical behavior. We describe how aspects of the dynamics change as the\njamming density is approached and how these dynamics can be explored using\nexternally driven probes. Different particle shapes can produce jamming\ndensities much lower than those observed for disk-shaped particles, and we show\nhow jamming exhibits fragility for some shapes while for other shapes this is\nabsent. Next we describe the effects of long range interactions and jamming\nbehavior in systems such as charged colloids, vortices in type-II\nsuperconductors, and dislocations. We consider the effect of adding obstacles\nto frictionless jamming systems and discuss connections between this type of\njamming and systems that exhibit depinning transitions. Finally, we discuss\nopen questions such as whether the jamming transition in all these different\nsystems can be described by the same or a small subset of universal behaviors,\nas well as future directions for studies of jamming transitions in two\ndimensional systems, such as jamming in self-driven or active matter systems.",
        "positive": "Numerical study of multilayer adsorption on fractal surfaces: We report a numerical study of van der Waals adsoprtion and capillary\ncondensation effects on self-similar fractal surfaces. An assembly of uncoupled\nspherical pores with a power-law distributin of radii is used to model fractal\nsurfaces with adjustable dimensions. We find that the commonly used fractal\nFrankel-Halsey-Hill equation systematically fails to give the correct dimension\ndue to crossover effects, consistent with the findings of recent experiments.\nThe effects of pore coupling and curvature dependent surface tension were also\nstudied."
    },
    {
        "anchor": "Electro-hydrodynamics of binary electrolytes driven by modulated surface\n  potentials: We study the electro-hydrodynamics of the Debye screening layer that arises\nin an aqueous binary solution near a planar insulating wall when applying a\nspatially modulated AC-voltage. Combining this with first order perturbation\ntheory we establish the governing equations for the full non-equilibrium\nproblem and obtain analytic solutions in the bulk for the pressure and velocity\nfields of the electrolyte and for the electric potential. We find good\nagreement between the numerics of the full problem and the analytics of the\nlinear theory. Our work provides the theoretical foundations of circuit models\ndiscussed in the literature. The non-equilibrium approach also reveals\nunexpected high-frequency dynamics not predicted by circuit models.",
        "positive": "Semiflexible Polymers Under Good Solvent Conditions Interacting With\n  Repulsive Walls: Solutions of semiflexible polymers confined by repulsive planar walls are\nstudied by density functional theory and Molecular Dynamics simulations, to\nclarify the competition between the chain alignment favored by the wall and the\ndepletion caused by the monomer-wall repulsion. A coarse-grained bead-spring\nmodel with bond bending potential is studied, varying both the contour length\nand the persistence length of the polymers, as well as the monomer\nconcentration in the solution (good solvent conditions are assumed throughout,\nand solvent molecules are not included explicitly). The profiles of monomer\ndensity and pressure tensor components near the wall are studied, and the\nsurface tension of the solution is obtained. While the surface tension slightly\ndecreases with chain length for flexible polymers, it clearly increases with\nchain length for stiff polymers. Thus, at fixed density and fixed chain length\nthe surface tension also increases with increasing persistence length. Chain\nends always are enriched near the wall, but this effect is much larger for\nstiff polymers than for flexible ones. Also the profiles of the mean square\ngyration radius components near the wall and the nematic order parameter are\nstudied to clarify the conditions where wall-induced nematic order occurs."
    },
    {
        "anchor": "A Thermodynamic Treatment\\\\ of Partially Saturated Soils \\\\ Revealing\n  the Structure of Effective Stress: A rigorous thermodynamic treatment of partially saturated soils is developed\nusing a minimal number of assumptions. The derivation is carried out in a way\nthat does not require to explicitly track the complex shapes of interfaces\nbetween the solid, fluid and gas domains. Instead, suction is the property\nbeing recovered explicitly through the minimisation of energy around an ideal\n`suctionless limit', while considering the different compressibilities of the\nthree domains. In interpreting experimental data the derivation ensures the\nthermodynamic equilibrium between the chemical potentials of the soil and\nmeasurement cells, while carefully distinguishing intrinsic from measured\npressures and suctions. A most general expression for the effective stress of\npartially saturated soils is then derived that is strictly linked to the\nsoil-water retention curve (SWRC). The structure of the effective stress\nbroadly depends on the three thermodynamic densities characterising the solid,\nfluid and gas domains. Special cases of SWRC are explored, which reveals\nconditions for which the structure of the effective stress may agree with\npreviously proposed empirical relationships.",
        "positive": "Coarse grained model for skyrmion dynamics: Liquid crystal skyrmions are topologically protected spatially localized\ndistortions of the director field which are fascinating from both fundamental\nmathematics and applied physics points of view. Skyrmions are realized in\nexperimental setups which are identical to those used in display technology.\nThis opens exciting opportunities for designing advanced electro-optical\napplications. Skyrmions exhibits particle-like properties including\ntranslational motion in time periodic electric fields. Despite a large volume\nof experimental results on the skyrmion collective behaviour, the theoretical\nunderstanding of their effective interactions and emerging dynamics is rather\nlimited due to computational heaviness of numerical models based upon fine\ngrained Frank-Oseen or Landau-de Gennes continuum approaches. Here, we develop\na coarse grained model of the skyrmion dynamics. The model reveals the\nunderpinning physical mechanism of the skyrmion motion driven by pulse width\nmodulated electric fields. The mechanism is based upon the complex dynamics of\nthe width of the twist wall around the skyrmion's core. The width evolves in a\nnon-reciprocal way within each on and off states of the field, resulting in a\nnet displacement of the skyrmion. We analyse in details the average skyrmion\nvelocity as a function of the frequency and strength of the field as well as\nits duty cycle. The model predictions agrees qualitatively with the results of\nexperiments and full numerical minimization of the fine grained models. Our\nresults provide insights into the conditions necessary to observe velocity\nreversal as a function of the field parameters."
    },
    {
        "anchor": "Evolution of force networks in dense granular matter close to jamming: When dense granular systems are exposed to external forcing, they evolve on\nthe time scale that is typically related to the externally imposed one (shear\nor compression rate, for example). This evolution could be characterized by\nobserving temporal evolution of contact networks. However, it is not\nimmediately clear whether the force networks, defined on contact networks by\nconsidering force interactions between the particles, evolve on a similar time\nscale. To analyze the evolution of these networks, we carry out discrete\nelement simulations of a system of soft frictional disks exposed to compression\nthat leads to jamming. By using the tools of computational topology, we show\nthat close to jamming transition, the force networks evolve on the time scale\nwhich is much faster than the externally imposed one. The presentation will\ndiscuss the factors that determine this fast time scale.",
        "positive": "Demixing and orientational ordering in mixtures of rectangular particles: Using scaled-particle theory for binary mixtures of two-dimensional hard\nparticles with rotational freedom, we analyse the stability of nematic phases\nand the demixing phase behaviour of a variety of mixtures, focussing on cases\nwhere at least one of the components consists of hard rectangles or hard\nsquares. A pure fluid of hard rectangles may exhibit, aside from the usual\nuniaxial nematic phase, an additional (tetratic) oriented phase, possessing two\ndirectors, which is the analogue of the biaxial or cubatic phases in three-\ndimensional fluids. There is computer simulation evidence that the tetratic\nphase might be stable with respect to phases with spatial order for rectangles\nwith low aspect ratios. As hard rectangles are mixed with other particles not\npossessing stable tetratic order by themselves, the tetratic phase is\ndestabilised, via a first- or second-order phase transition, to uniaxial\nnematic or isotropic phases; for hard rectangles of low aspect ratio tetratic\norder persists in a relatively large range of volume fractions. The order of\nthese transitions depends on the particle geometry, dimensions and\nthermodynamic conditions of the mixture. The second component of the mixture\nhas been chosen to be hard discs or disco-rectangles, the geometry of which is\ndifferent from that of rectangles, leading to packing frustration and demixing\nbehaviour, or simply rectangles of different aspect ratio. These mixtures may\nbe good candidates for observing thermodynamically stable tetratic phases in\nmonolayers of hard particles. Finally, demixing between fluid\n(isotropic--tetratic or tetratic--tetratic) phases is seen to occur in mixtures\nof hard squares of different sizes when the size ratio is sufficiently large."
    },
    {
        "anchor": "Stochastic curvature of enclosed semiflexible polymers: The conformational states of a semiflexible polymer enclosed in a compact\ndomain of typical size $a$ are studied as stochastic realizations of paths\ndefined by the Frenet equations under the assumption that stochastic\n\"curvature\" satisfies a white noise fluctuation theorem. This approach allows\nus to derive the Hermans-Ullman equation, where we exploit a multipolar\ndecomposition that allows us to show that the positional probability density\nfunction is well described by a Telegrapher's equation whenever\n$2a/\\ell_{p}>1$, where $\\ell_{p}$ is the persistence length. We also develop a\nMonte Carlo algorithm for use in computer simulations in order to study the\nconformational states in a compact domain. In addition, the case of a\nsemiflexible polymer enclosed in a square domain of side $a$ is presented as an\nexplicit example of the formulated theory and algorithm. In this case, we show\nthe existence of a polymer shape transition similar to the one found by\nSpakowitz and Wang [Phys. Rev. Lett. {\\bf 91}, 2 (2003)] where in this case the\ncritical persistence length is $\\ell^{*}_{p}\\simeq a/8$ such that the\nmean-square end-to-end distance exhibits an oscillating behavior for values\n$\\ell_{p}>\\ell^{*}_{p}$, whereas for $\\ell_{p}<\\ell^{*}_{p}$ it behaves\nmonotonically increasing.",
        "positive": "Microliter viscometry using a bright-field microscope: $\u03b7$-DDM: Passive microrheology exploits the Brownian motion of colloidal tracer\nparticles. From the mean-squared displacement (MSD) of the tracers, the bulk\nrheological and viscometric properties of the host medium can be inferred.\nHere, the MSD is determined by applying Differential Dynamic Microscopy (DDM).\nCompared to other microscopy techniques, DDM avoids particle tracking but\nprovides parameters commonly acquired in light scattering experiments. Based on\nthe spatial Fourier transform of image differences, the intermediate scattering\nfunction and subsequently the MSD is calculated. Then the usual microrheology\nprocedure and the empirical Cox-Merz rule yield the steady-shear viscosity.\nThis method, $\\eta$-DDM, is tested and illustrated using three different\nsystems: Newtonian fluids (glycerol-water mixtures), colloidal suspensions\n(protein samples) and a viscoelastic polymer solution (aqueous poly(ethylene\noxide) solution). These tests show that common lab equipment, namely a\nbright-field optical microscope, can be used as a convenient and reliable\nmicroliter viscometer. Because $\\eta$-DDM requires much smaller sample volumes\nthan classical rheometry, only about a microliter, it is particularly useful\nfor biological and soft matter systems."
    },
    {
        "anchor": "Ion-mediated interactions between net-neutral slabs: Weak and strong\n  disorder effects: We investigate the effective interaction between two randomly charged but\notherwise net-neutral, planar dielectric slabs immersed in an asymmetric\nCoulomb fluid containing a mixture of mobile monovalent and multivalent ions.\nThe presence of charge disorder on the apposed bounding surfaces of the slabs\nleads to substantial qualitative changes in the way they interact, as compared\nwith the standard picture provided by the van der Waals and image-induced,\nion-depletion interactions. While, the latter predict purely attractive\ninteractions between strictly neutral slabs, we show that the combined effects\nfrom surface charge disorder, image depletion, Debye (or salt) screening and\nalso, in particular, their coupling with multivalent ions, give rise to a more\ndiverse behavior for the effective interaction between net-neutral slabs.\nDisorder effects show large variation depending on the properly quantified\nstrength of disorder, leading either to non-monotonic effective interaction\nwith both repulsive and attractive branches when the surface charges are weakly\ndisordered (small disorder variance) or to a dominating attractive interaction\nthat is larger both in its range and magnitude than what is predicted from the\nvan der Waals and image-induced, ion-depletion interactions, when the surfaces\nare strongly disordered (large disorder variance).",
        "positive": "A theory of flying/swimming saucers. Exact solutions for rectilinear\n  locomotion: We study self-propulsion (or locomotion) of a robot (or an underwater\nvehicle) in an inviscid incompressible fluid. The robot's body is rigid, while\nits locomotion ability is due to an internal actuator, which can perform\ncontrolled translational and rotational oscillations. Our attention is focused\non two classes of the plane analytic exact solutions, describing rectilinear\nlocomotion. Solutions of the first class describe the \\emph{tumbling\nlocomotion}, while the second class corresponds to the \\emph{zigzag locomotion}\nwithout tumbling. We show, that tumbling locomotion is more efficient. Both\nclasses of solutions show, that the use of actuator allows to choose any\ndesired direction and any speed of locomotion. As a special case, we consider\nthe self-propulsion caused by small-amplitude and high-frequency actuator\noscillations. The exact and elementary character of our solutions makes the\nresults potentially useful as the tests to verify physical and engineering\nmodels, as well as numerical and asymptotic results. In contrary to many recent\npublications in this area, the material is accessible to UG students in\nEngineering, Physics, and Applied Mathematics."
    },
    {
        "anchor": "Vortex Creation in Bose-Einstein Condensates by Diffraction on a Helical\n  Light Grating: It is shown that diffraction of Bose-Einstein condensates on a helical light\ngrating results in vortices in the condensate. Helical light gratings can be\nproduced by light interference of a Gaussian laser beam with a helical one.\nDiffraction orders of the Bose-Einstein condensate contain vortices of\ncorresponding topological charge. The phenomena is illustrated by numerical\nintegration of the Gross-Pitaevskii equation in two dimensions.",
        "positive": "Bogoliubov excitation spectrum in anharmonic traps: We study the linearized Bogoliubov excitation spectrum of infinitely long\nanharmonically trapped Bose-Einstein condensates, with the aim of overcoming\ninhomogeneous broadening. We compare the Bogoliubov spectrum of a harmonic trap\nwith that of a theoretical flat-bottom trap and find a dramatic reduction in\nthe inhomogeneous broadening of the lineshape of Bogoliubov excitations. While\nthe Bragg excitation spectrum for a condensate in a harmonic trap supports a\nnumber of radial modes, the flat trap is found to significantly support just\none mode. We also study the excitation spectrum of realistic anharmonic traps\nwith potentials of finite power dependence on the radial coordinate. We observe\na correlation between the number of radial modes and the number of bound states\nin the effective potential of the quasi-particles. Finally we compare a full\nnumerical Gross-Pitaevskii simulation of a finite-length condensate to our\nmodel of infinite, linearized Gross-Pitaevskii excitations. We conclude that\nour model captures the essential physics."
    },
    {
        "anchor": "Glass transition of hard spheres in high dimensions: We have investigated analytically and numerically the liquid-glass transition\nof hard spheres for dimensions $d\\to \\infty $ in the framework of mode-coupling\ntheory. The numerical results for the critical collective and self\nnonergodicity parameters $f_{c}(k;d) $ and $f_{c}^{(s)}(k;d) $ exhibit\nnon-Gaussian $k$ -dependence even up to $d=800$. $f_{c}^{(s)}(k;d) $ and\n$f_{c}(k;d) $ differ for $k\\sim d^{1/2}$, but become identical on a scale\n$k\\sim d$, which is proven analytically. The critical packing fraction\n$\\phi_{c}(d) \\sim d^{2}2^{-d}$ is above the corresponding Kauzmann packing\nfraction $\\phi_{K}(d)$ derived by a small cage expansion. Its quadratic\npre-exponential factor is different from the linear one found earlier. The\nnumerical values for the exponent parameter and therefore the critical\nexponents $a$ and $b$ depend on $d$, even for the largest values of $d$.",
        "positive": "Thermodynamics of interface in the freezing of colloidal suspensions:\n  from macroscale to the microscale: A long controversy of ice lensing exists in the research of frost heave. By\nelucidating the mechanical and thermodynamics equilibria at the interface, we\npresent the thermodynamics of the water/ice interface from macroscale to\nmicroscale for the freezing of colloidal suspensions. The application of the\nClapeyron equation is confirmed both at macroscale to microscale via curvature\neffect. The thermodynamics at the interface indicates the initial of ice\nlensing/banding from the growth of pore ice, determined by the critical\ncurvature undercooling instead of the critical fracture of frozen fringe. It is\nalso proposed that the packing status of the porous structure in the particle\nlayer ahead of the water/ice interface determines the ice lensing behaviors.\nThe results presented here are different scenarios from previous investigations\nof freezing colloidal suspensions, and may shed light on the researches of this\narea."
    },
    {
        "anchor": "Elasticity of Filamentous Kagome Lattice: The diluted kagome lattice, in which bonds are randomly removed with\nprobability $1-p$, consists of straight lines that intersect at points with a\nmaximum coordination number of four. If lines are treated as semi-flexible\npolymers and crossing points are treated as crosslinks, this lattice provides a\nsimple model for two-dimensional filamentous networks. Lattice-based effective\nmedium theories and numerical simulations for filaments modeled as elastic\nrods, with stretching modulus $\\mu$ and bending modulus $\\kappa$, are used to\nstudy the elasticity of this lattice as functions of $p$ and $\\kappa$. At\n$p=1$, elastic response is purely affine, and the macroscopic elastic modulus\n$G$ is independent of $\\kappa$. When $\\kappa = 0$, the lattice undergoes a\nfirst-order rigidity percolation transition at $p=1$. When $\\kappa > 0$, $G$\ndecreases continuously as $p$ decreases below one, reaching zero at a\ncontinuous rigidity percolation transition at $p=p_b \\approx 0.605$ that is the\nsame for all non-zero values of $\\kappa$. The effective medium theories predict\nscaling forms for $G$, which exhibit crossover from bending dominated response\nat small $\\kappa/\\mu$ to stretching-dominated response at large $\\kappa/\\mu$\nnear both $p=1$ and $p=p_b$, that match simulations with no adjustable\nparameters near $p=1$. The affine response as $p\\rightarrow 1$ is identified\nwith the approach to a state with sample-crossing straight filaments treated as\nelastic rods.",
        "positive": "Fine particle percolation in a sheared granular bed: We study the percolation velocity, $v_p,$ of a fine spherical particle in a\nsheared large-particle bed under gravity using discrete element method\nsimulations for large-to-fine particle diameter ratios, $R=d/d_f,$ below and\nabove the free-sifting threshold, $R_t\\approx6.5.$ For $R<R_t,$ $v_p$ initially\nincreases with increasing shear rate, $\\dot\\gamma,$ as shear-driven bed\nrearrangement reduces fine-particle trapping but then decreases toward zero due\nto fine-particle excitation for $\\dot\\gamma\\sqrt{d/g}\\gtrsim 0.1$. For $R>R_t$,\n$v_p$ is constant at low $\\dot\\gamma$ but decreases toward zero at higher shear\nrates due to fine-particle excitation."
    },
    {
        "anchor": "Adsorption superlattice stabilized by elastic interactions in a soft\n  porous crystal: We numerically show that molecules adsorbed in a soft porous crystal form a\nsuperlattice (SL) stabilized by elastic interactions. In a mechanically\nflexible honeycomb lattice model, when the elastic interactions between the\nnext nearest neighboring lattice sites are strong, a long-range ordered\n1/3-filling SL state emerges. By calculating the thermodynamic stability, it is\nfound that the SL state is robust against thermal fluctuation. Our results\nprovide a mechanism of elasticity-driven SL formation, which can be utilized\nfor controlling the distribution of adsorbed molecules.",
        "positive": "Fluctuation-dissipation relations and energy landscape in an\n  out-of-equilibrium strong glass-forming liquid: We study the out-of-equilibrium dynamics following a temperature-jump in a\nmodel for a strong liquid, BKS-silica, and compare it with the well known case\nof fragile liquids. We calculate the fluctuation-dissipation relation, from\nwhich it is possible to estimate an effective temperature $T_{eff}$ associated\nto the slow out-of-equilibrium structural degrees of freedom. We find the\nstriking and unexplained result that, differently from the fragile liquid\ncases, $T_{eff}$ is smaller than the bath temperature."
    },
    {
        "anchor": "Accelerated Design of Block Copolymers: An Unbiased Exploration Strategy\n  via Fusion of Molecular Dynamics Simulations and Machine Learning: Star block copolymers (s-BCPs) have potential applications as novel\nsurfactants or amphiphiles for emulsification, compatbilization, chemical\ntransformations and separations. s-BCPs are star-shaped macromolecules\ncomprised of linear chains of different chemical blocks (e.g., solvophilic and\nsolvophobic blocks) that are covalently joined at one junction point. Various\nparameters of these macromolecules can be tuned to obtain desired surface\nproperties, including the number of arms, composition of the arms, and the\ndegree-of-polymerization of the blocks (or the length of the arm). This makes\nidentification of the optimal s-BCP design highly non-trivial as the total\nnumber of plausible s-BCPs architectures is experimentally or computationally\nintractable. In this work, we use molecular dynamics (MD) simulations coupled\nwith reinforcement learning based Monte Carlo tree search (MCTS) to identify\ns-BCPs designs that minimize the interfacial tension between polar and\nnon-polar solvents. We first validate the MCTS approach for design of small-\nand medium-sized s-BCPs, and then use it to efficiently identify sequences of\ncopolymer blocks for large-sized s-BCPs. The structural origins of interfacial\ntension in these systems are also identified using the configurations obtained\nfrom MD simulations. Chemical insights on the arrangement of copolymer blocks\nthat promote lower interfacial tension were mined using machine learning (ML)\ntechniques. Overall, this work provides an efficient approach to solve design\nproblems via fusion of simulations and ML and provide important groundwork for\nfuture experimental investigation of s-BCPs sequences for various applications.",
        "positive": "Rheology, diffusion, and velocity correlations in the bubble model: We present results on spatio-temporal correlations in the so-called mean drag\nversion of the Durian bubble model in the limit of small, but finite, shearing\nrates, $\\dot{\\gamma}$. We study the rheology, diffusion, and spatial\ncorrelations of the instantaneous velocity field. The quasi-static (QS)\neffective diffusion co-efficient, $D_e$, shows an anomalous system size\ndependence indicative of organization of plastic slip into lines along the\ndirections of maximum shearing. At higher rates, $D_e$ decays like\n$\\dot{\\gamma}^{-1/3}$. The instantaneous velocity fields have a spatial\nstructure which is consistent with a set of spatially uncorrelated Eshelby\ntransformations. The correlations are cut off beyond a length, $\\xi$. $\\xi\\sim\n\\dot{\\gamma}^{-1/3}$ which explains the $D_e\\sim\\dot{\\gamma}^{-1/3}$ behavior.\nThe shear stress, $\\sigma$, follows a similar rate dependence with\n$\\delta\\sigma=\\sigma-\\sigma_y\\sim \\dot{\\gamma}^{1/3}$ where $\\sigma_y$ is the\nyield stress observed in the QS regime.These results indicate that the form for\nthe viscous dissipation can have a profound impact on the rheology, diffusion\nand spatial correlations in sheared soft glassy systems."
    },
    {
        "anchor": "Locomotion without force, and impulse via dissipation: Robotic swimming\n  in curved space via geometric phase: Locomotion by shape changes (spermatozoon swimming, snake slithering, bird\nflapping) or gas expulsion (rocket firing) is assumed to require environmental\ninteraction, due to conservation of momentum. As first noted in (Wisdom, 2003)\nand later in (Gu\\'eron, 2009) and (Avron et al, 2006), in curved space or\nspacetime the non-commutativity of translations permits translation without\nmomentum exchange, just as falling cats and lizards can self-deform to reorient\nin flat space without environmental interaction. Translation in curved space\ncan occur not only in gravitationally induced curved spacetime (where\ntranslation is predicted to be on the order of $10^{-23}$ m per gait cycle) but\nalso in the curved surfaces encountered by locomotors in real-world\nenvironments. Here we show that a precision robophysical apparatus consisting\nof motors driven on curved tracks (and thereby confined to a spherical surface\nwithout a solid substrate) can self-propel without environmental momentum\nexchange (impulse) via shape changes that can generate gauge potentials that\nmanifest as translations. Our system produces shape changes comparable to the\nenvironment's inverse curvatures and generates from zero momentum forward\nmovement of $10^{-1}$ cm per gait cycle even while resisted by weak\ngravitational and frictional forces. Dissipation via friction eventually\narrests the robot but also imbues it with momentum which can be released upon a\ncessation of shape changes. This work demonstrates how the interaction between\nenvironmental curvature, active driving and geometric phases yields rich,\nexotic phenomena.",
        "positive": "Cross-talk between topological defects in different fields revealed by\n  nematic microfluidics: Topological defects are singularities in material fields that play a vital\nrole across a range of systems: from cosmic microwave background polarization\nto superconductors, and biological materials. Although topological defects and\ntheir mutual interactions have been extensively studied, little is known about\nthe interplay between defects in different fields -- especially when they\nco-evolve -- within the same physical system. Here, using nematic\nmicrofluidics, we study the cross-talk of topological defects in two different\nmaterial fields -- the velocity field and the molecular orientational field.\nSpecifically, we generate hydrodynamic stagnation points of different\ntopological charges at the center of star-shaped microfluidic junctions, which\nthen interact with emergent topological defects in the orientational field of\nthe nematic director. We combine experiments, and analytical and numerical\ncalculations to demonstrate that a hydrodynamic singularity of given\ntopological charge can nucleate a nematic defect of equal topological charge,\nand corroborate this by creating $-1$, $-2$ and $-3$ topological defects in\n$4-$, $6-$, and $8-$arm junctions. Our work is an attempt toward understanding\nmaterials that are governed by distinctly multi-field topology, where disparate\ntopology-carrying fields are coupled, and concertedly determine the material\nproperties and response."
    },
    {
        "anchor": "Detachment Energies of Spheroidal Particles from Fluid-Fluid Interfaces: The energy required to detach a single particle from a fluid-fluid interface\nis an important parameter for designing certain soft materials, for example,\nemulsions stabilised by colloidal particles, colloidosomes designed for\ntargeted drug delivery, and bio-sensors composed of magnetic particles adsorbed\nat interfaces. For a fixed particle volume, prolate and oblate spheroids attach\nmore strongly to interfaces because they have larger particle-interface areas.\nCalculating the detachment energy of spheroids necessitates the difficult\nmeasurement of particle-liquid surface tensions, in contrast with spheres,\nwhere the contact angle suffices. We develop a simplified detachment energy\nmodel for spheroids which depends only on the particle aspect ratio and the\nheight of the particle centre of mass above the fluid-fluid interface. We use\nlattice Boltzmann simulations to validate the model and provide quantitative\nevidence that the approach can be applied to simulate particle-stabilized\nemulsions, and highlight the experimental implications of this validation.",
        "positive": "Surface Tension regularizes the Crack Singularity of Adhesive Contacts: The elastic and adhesive properties of a solid surface can be quantified by\nindenting it with a rigid sphere. Indentation tests are classically described\nby the JKR-law when the solid is very stiff, while recent work highlights the\nimportance of surface tension for exceedingly soft materials. Here we show that\nsurface tension plays a crucial role even for stiff solids: it regularizes the\ncrack-like singularity at the edge of the contact. We find that the edge region\nexhibits a universal, self-similar structure that emerges from the balance of\nsurface tension and elasticity. The similarity theory provides a complete\ndescription for adhesive contacts, reconciling the global adhesion laws and\nlocal contact mechanics."
    },
    {
        "anchor": "Spatial and temporal dynamical heterogeneities approaching the binary\n  colloidal glass transition: We study concentrated binary colloidal suspensions, a model system which has\na glass transition as the volume fraction $\\phi$ of particles is increased. We\nuse confocal microscopy to directly observe particle motion within dense\nsamples with $\\phi$ ranging from 0.4 to 0.7. Our binary mixtures have a\nparticle diameter ratio $d_S/d_L=1/1.3$ and particle number ratio\n$N_S/N_L=1.56$, which are chosen to inhibit crystallization and enable\nlong-time observations. Near the glass transition we find that particle\ndynamics are heterogeneous in both space and time. The most mobile particles\noccur in spatially localized groups. The length scales characterizing these\nmobile regions grow slightly as the glass transition is approached, with the\nlargest length scales seen being $\\sim 4$ small particle diameters. We also\nstudy temporal fluctuations using the dynamic susceptibility $\\chi_4$, and find\nthat the fluctuations grow as the glass transition is approached. Analysis of\nboth spatial and temporal dynamical heterogeneity show that the smaller species\nplay an important role in facilitating particle rearrangements. The glass\ntransition in our sample occurs at $\\phi_g \\approx 0.58$, with characteristic\nsigns of aging observed for all samples with $\\phi>\\phi_g$.",
        "positive": "Universal scaling dynamics in a perturbed granular gas: We study the response of a granular system at rest to an instantaneous input\nof energy in a localised region. We present scaling arguments that show that,\nin $d$ dimensions, the radius of the resulting disturbance increases with time\n$t$ as $t^{\\alpha}$, and the energy decreases as $t^{-\\alpha d}$, where the\nexponent $\\alpha=1/(d+1)$ is independent of the coefficient of restitution. We\nsupport our arguments with an exact calculation in one dimension and event\ndriven molecular dynamic simulations of hard sphere particles in two and three\ndimensions."
    },
    {
        "anchor": "A JKR solution for a ball-in-socket contact geometry as a bi-stable\n  adhesive system: In the present note, we start by observing that in the classical JKR theory\nof adhesion, using the usual Hertzian approximations, the pull-off load grows\nunbounded when the clearance goes to zero in a conformal \"ball in socket\"\ngeometry. To consider the case of the conforming geometry, we use a recent\nrigorous general extension of the original JKR energetic derivation proposed by\nthe first author which necessitates only of adhesionless solutions, and an\napproximate adhesionless solution given in the literature. We find that\ndepending on a single governing parameter of the problem, theta=DeltaR/(2 pi w\nR E*) where E* is the plane strain elastic modulus of the material couple, w\nthe surface energy, DeltaR the clearance and R the radius of the sphere, the\nsystem shows the classical bistable behaviour for a single sinusoid or a\ndimpled surface: pull off is approximately that of the JKR theory for\ntheta>0.82 only if the system is not \"pushed\" strongly enough and otherwise a\n\"strong adhesion\" regime is found. Below this value theta<0.82, a strong\nspontaneous adhesion regime is found similar to \"full contact\". From the strong\nregime, pull-off will require a separate investigation depending on the actual\nsystem at hand.",
        "positive": "Dissipative dynamics of vortex arrays in trapped Bose-condensed gases:\n  neutron stars physics on $\u03bc$K scale: We develop a theory of dissipative dynamics of large vortex arrays in trapped\nBose-condensed gases. We show that in a static trap the interaction of the\nvortex array with thermal excitations leads to a non-exponential decay of the\nvortex structure, and the characteristic lifetime depends on the initial\ndensity of vortices. Drawing an analogy with physics of pulsar glitches, we\npropose an experiment which employs the heating of the thermal cloud in the\ncourse of the decay of the vortex array as a tool for a non-destructive study\nof the vortex dynamics."
    },
    {
        "anchor": "Metastable tight knots in a worm-like polymer: Based on an estimate of the knot entropy of a worm-like chain we predict that\nthe interplay of bending energy and confinement entropy will result in a\ncompact metastable configuration of the knot that will diffuse, without\nspreading, along the contour of the semi-flexible polymer until it reaches one\nof the chain ends. Our estimate of the size of the knot as a function of its\ntopological invariant (ideal aspect ratio) agrees with recent experimental\nresults of knotted dsDNA. Further experimental tests of our ideas are proposed.",
        "positive": "Spontaneous free-boundary structure in crumpled membranes: We investigate the strong curvature that appears at the boundaries of a thin\ncrumpled elastic membrane. We account for these high-curvature regions in terms\nof the stretching-ridge singularity believed to dominate the structure of\nstrongly deformed elastic membranes. Using a membrane fastened to itself to\nform a bag shape with a single stretching ridge, we show that the creation of\npoints of high boundary curvature lowers the interior ridge's energy. In the\nlimit of small thickness, the induced curvature becomes arbitrarily strong on\nthe scale of the object size and results in sharp edges connecting interior\nvertices to the boundary. REVISED: We analyze these edges as conical sectors\nwith no stretching. As the membrane size diverges, the edge energy grows as the\nsquare root of the central ridge energy. For comparison, we discuss the effect\nof truncating a stretching ridge at its ends. The effect of truncation becomes\nappreciable when the truncation length is comparable to the width of the\nuntruncated ridge."
    },
    {
        "anchor": "Role of reversibility in viral capsid growth: A paradigm for\n  self-assembly: Self-assembly at submicroscopic scales is an important but little understood\nphenomenon. A prominent example is virus capsid growth, whose underlying\nbehavior can be modeled using simple particles that assemble into polyhedral\nshells. Molecular dynamics simulation of shell formation in the presence of an\natomistic solvent provides new insight into the self-assembly mechanism,\nnotably that growth proceeds via a cascade of strongly reversible steps and,\ndespite the large variety of possible intermediates, only a small fraction of\nhighly bonded forms appear on the pathway.",
        "positive": "Complexity in surfaces of densest packings for families of polyhedra: Packings of hard polyhedra have been studied for centuries due to their\nmathematical aesthetic and more recently for their applications in fields such\nas nanoscience, granular and colloidal matter, and biology. In all these\nfields, particle shape is important for structure and properties, especially\nupon crowding. Here, we explore packing as a function of shape. By combining\nsimulations and analytic calculations, we study three 2-parameter families of\nhard polyhedra and report an extensive and systematic analysis of the densest\npackings of more than 55,000 convex shapes. The three families have the\nsymmetries of triangle groups (icosahedral, octahedral, tetrahedral) and\ninterpolate between various symmetric solids (Platonic, Archimedean, Catalan).\nWe find that optimal (maximum) packing density surfaces that reveal unexpected\nrichness and complexity, containing as many as 130 different structures within\na single family. Our results demonstrate the utility of thinking of shape not\nas a static property of an object in the context of packings, but rather as but\none point in a higher dimensional shape space whose neighbors in that space may\nhave identical or markedly different packings. Finally, we present and\ninterpret our packing results in a consistent and generally applicable way by\nproposing a method to distinguish regions of packings and classify types of\ntransitions between them."
    },
    {
        "anchor": "A Knowledge-driven Physics-Informed Neural Network model; Pyrolysis and\n  Ablation of Polymers: In aerospace applications, multiple safety regulations were introduced to\naddress associated with pyrolysis. Predictive modeling of pyrolysis is a\nchallenging task since multiple thermo-chemo-mechanical laws need to be\nconcurrently solved at each time step. So far, classical modeling approaches\nwere mostly focused on defining the basic chemical processes (pyrolysis and\nignite) at micro-scale by decoupling them from thermal solution at the\nmicro-scale and then validating them using meso-scale experimental results. The\nadvent of Machine Learning (ML) and AI in recent years has provided an\nopportunity to construct quick surrogate ML models to replace high fidelity\nmulti-physics models, which have a high computational cost and may not be\napplicable for high nonlinear equations. This serves as the motivation for the\nintroduction of innovative Physics informed neural networks (PINNs) to simulate\nmultiple stiff, and semi-stiff ODEs that govern Pyrolysis and Ablation. Our\nEngine is particularly developed to calculate the char formation and degree of\nburning in the course of pyrolysis of crosslinked polymeric systems. A\nmulti-task learning approach is hired to assure the best fitting to the\ntraining data. The proposed Hybrid-PINN (HPINN) solver was bench-marked against\nfinite element high fidelity solutions on different examples. We developed PINN\narchitectures using collocation training to forecast temperature distributions\nand the degree of burning in the course of pyrolysis in multiple one- and\ntwo-dimensional examples. By decoupling thermal and mechanical equations, we\ncan predict the loss of performance in the system by predicting the char\nformation pattern and localized degree of burning at each continuum.",
        "positive": "Crumpling of Curved Sheets: Generalizing Foeppl-von Karman: We generalize the F\\\"{o}ppl-von K\\'arm\\'an equations to an initially\nprecurved sheet and present the underlying derivation. A geometrically computed\nmoment of strain replaces the notion of bending moment and results in a\ngeometric formulation of the theory of shells. As the curvature approaches\nzero, i.e., the sheet becomes flat, the new equations reduce to the classic\nF\\\"{o}ppl-von K\\'arm\\'an ones. The present theory solves the long-standing\nproblem of formulating these equations for an a priori curved shell and\napplies, for instance, both to shell theory and to strongly curved biomembranes\nof cells as closed surfaces, exhibiting crumpling as the membrane thickness\ngoes to zero."
    },
    {
        "anchor": "Capillary Rise and Imbibition of Liquids in Nanoporous Matrices:\n  Rheological Concepts and Experiments: Liquid flow propelled by capillary forces is one of the most important\ntransport mechanisms in porous environments. It is governed by a fascinating\ninterplay of interfacial, viscous drag as well as gravitational forces which\nliquids encounter upon invasion into geometries with often complex topologies,\nsuch as capillary networks of trees or interconnected fractures in soils and\nice. Here, we present fundamentals, concepts and an experimental, gravimetric\nstudy on the capillarity-driven invasion dynamics of liquids in networks of\npores a few nanometers across in monolithic, nanoporous silica glass (porous\nVycor). A variation of the complexity of the building blocks of the liquids\ninvestigated along with a variation of the humidity and the temperature upon\nspontaneous imbibition allows us to gain information regarding the fluidity and\ncapillarity of liquids in such nanoporous environments. We observe square-root\nof time imbibition dynamics for all liquids applied, which we can\nquantitatively describe by both a conserved bulk fluidity in the pore center\nand bulk capillarity at the advancing menisci, if we assume a sticky boundary\nlayer (negative velocity slip length). Moreover, pecularities of\nnanopore-confined liquids, such as transport via the vapor phase leading to\npreadsorbed liquid layers, have to be properly accounted for. Upon increasing\nthe chain-length in the case of the n-alkanes, we found hints towards a\ntransition from stick- to slip-flow at the pore walls with increasing\nchain-length and thus polymeric behavior. Meniscus freezing is reported for\nn-tetracosane confined in porous Vycor. For the rheology of a rod-like liquid\nnematogen (8OCB) we found no hints of the viscosity drop upon entering into the\nnematic phase, typical of the bulk rheology of this liquid crystal.",
        "positive": "Depletion-driven Morphological Transitions in Hexagonal Crystallites of\n  Virus Rods: The assembly of nanometer-sized building blocks into complex morphologies is\nnot only of fundamental interest but also plays a key role in material science\nand nanotechnology. We show that the shape of self-assembled superstructures\nformed by rod-like viruses can be controlled by tuning the attraction via the\ndepletion interaction between the rods. Using nonadsorbing polymers as a\ndepleting agent, we demonstrate that a hierarchical unidimensional\nself-organization into crystalline clusters emerges progressively upon\nincreasing depletion attraction -and enhanced growth kinetics. We observe a\npolymorphic change proceeding from two-dimensional (2D) crystalline monolayers\nat weak depletion to one-dimensional (1D) columnar fibers at strong depletion,\nvia the formation of smectic fibrils at intermediate depletion strength. A\nsimple theory for reversible polymerization enables us to determine the typical\nbond energy between monomeric units making up the smectic fibrils. We also\ndemonstrate that gentle flow-assistance can be used to template filament-like\nstructures into highly aligned supported films. Our results showcase a generic\nbottom-up approach for tuning the morphology of crystalline superstructures\nthrough modification of the interaction between non-spherical building blocks.\nThis provides a convenient pathway for controlling self-organization,\ndimensionality and structure-formation of anisotropic nanoparticles for use in\nnanotechnology and functional materials."
    },
    {
        "anchor": "Crystallization of Diblock Copolymer from Microphase Separated Melt: Diblock copolymers by virtue of the chemical dissimilarity between the\nconstituting blocks exhibit microphase separation in the melt state. The phase\nseparated melt can successfully be exploited to control the morphology of the\nfinal semi crystalline materials by allowing an extended thermal annealing.\nThermal annealing accelerates coalescence of microdomains, yielding a phase\nseparated melt that would exhibit a distinctly different crystallization\nbehaviour than microphase separated melt without annealing. In this paper, we\nreport simulation results on the crystallization behavior of A-B diblock\ncopolymer, wherein the melting temperature of A-block is higher than B-block,\ninstigated from microphase separated melt. During crystallization, the\nmorphological evolution of microphase separated melt is extensively driven by\nthermal history. Annealing of microphase separated melt at high temperature\nsuccessfully reorients melt morphology, and remains almost unaltered during the\nsubsequent crystallization (isothermal and non-isothermal), which is attributed\nto the hard confinement resulted during microphase separation. Annealing\ninduces a change in bond orientation of A-block, whereas there is no\nappreciable change in bond orientation of B-block keeping crystallinity and\nlamellar thickness unaffected. Isothermal crystallization confines\ncrystallization in phase separated microdomain whereas non-isothermal\ncrystallization results in morphological perturbation. The crystallization rate\nof annealed melt is much faster than the non-annealed melt due to less\nentanglement and more relaxed structure, achieved via annealing. At a higher\ncomposition of B-block, A-block produces thicker crystals, which is attributed\nto the dilution effect exhibited by B-block. Two-step compared to one-step\nisothermal crystallization yields thicker crystals with higher crystallinity of\nA-block.",
        "positive": "Jamming Energy Landscape is Hierarchical and Ultrametric: The free energy landscape of mean field marginal glasses is ultrametric. We\ndemonstrate that this feature remains in finite three dimensional systems by\nfinding sets of minima which are nearby in configuration space. By calculating\nthe distance between these nearby minima, we produce a small region of the\ndistance metric. This metric exhibits a clear hierarchical structure and shows\nthe signature of an ultrametric space. That such a hierarchy exists for the\njamming energy landscape provides direct evidence for the existence of a\nmarginal phase along the zero temperature jamming line."
    },
    {
        "anchor": "Stabilizing quasicrystals composed of patchy colloids by narrowing the\n  patch width: We explore the behavior of two-dimensional patchy colloidal particles with 8\nor 10 symmetrically arranged patches by employing Monte-Carlo simulations. The\nparticles interact according to an isotropic pair potential that possesses only\none typical length. The patches lead to additional attractions that are\nanisotropic and depend on the relative orientation of two neighboring\nparticles. We investigate the assembled structures with a special interest in\nquasicrystals. We found that the patch width is of great importance: Only in\ncase of narrow patch widths we are able to observe metastable octagonal and\ndecagonal quasicrystals, while dodecagonal quasicrystals can also occur for\nbroad patches. These results are important to understand the role of\ninteractions with preferred binding angles in order to obtain quasicrystals.\nOur findings suggest that in case of sharp binding angles, as they occur in\nmetallic alloys, octagonal and decagonal symmetries might be observed more\noften than in systems with less sharp binding angles as it is the case in soft\nmatter systems where dodecagonal quasicrystals dominate.",
        "positive": "Measuring the nematic order of colloidal fd virus by xray diffraction: The orientational distribution function of the nematic phase of the\nsemi-flexible rod-like virus fd is measured by x-ray diffraction as a function\nof concentration and ionic strength. The angular distribution of the scattered\nintensity from a single-domain nematic phase of fd arises from only the single\nparticle orientational distribution function at high angle but it also includes\nspatial and orientational correlations at low angle. Experimental measurements\nof the orientational distribution function from both the interparticle and\nintraparticle scattering were made to test whether the correlations present in\ninterparticle scatter influence the measurement of the single particle\norientational distribution function. It was found that the two types of scatter\nyield consistent values for the nematic order parameter. It was also found that\nx-ray diffraction is insensitive to the orientational distribution function's\nprecise form, and the measured angular intensity distribution is described\nequally well by both Onsager's trial function and a Gaussian. At high ionic\nstrength the order parameter S of the nematic phase coexisting with the\nisotropic phase approaches theoretical predictions for long semi-flexible rods\nS=0.55, but deviations from theory increase with decreasing ionic strength. The\nconcentration dependence of the nematic order parameter was also found to\nbetter agree with theoretical predictions at high ionic strength, indicating\nthat electrostatic interactions have a measurable effect on the nematic order\nparameter. The measured x-ray order parameters are also shown to be\nproportional to the measured birefringence and the saturation birefringence of\nfd is measured, enabling a simple, inexpensive way to measure the order\nparameter."
    },
    {
        "anchor": "Pulse propagation in tapered granular chains: An analytic study: We study pulse propagation in one-dimensional tapered chains of spherical\ngranules. Analytic results for the pulse velocity and other pulse features are\nobtained using a binary collision approximation. Comparisons with numerical\nresults show that the binary collision approximation provides quantitatively\naccurate analytic results for these chains.",
        "positive": "Crystal structures and freezing of dipolar fluids: We investigate the crystal structure of classical systems of spherical\nparticles with an embedded point dipole at T=0. The ferroelectric ground state\nenergy is calculated using generalizations of the Ewald summation technique.\nDue to the reduced symmetry compared to the nonpolar case the crystals are\nnever strictly cubic. For the Stockmayer (i.e., Lennard-Jones plus dipolar)\ninteraction three phases are found upon increasing the dipole moment:\nhexagonal, body-centered orthorhombic, and body-centered tetragonal. An even\nricher phase diagram arises for dipolar soft spheres with a purely repulsive\ninverse power law potential $\\sim r^{-n}$. A crossover between qualitatively\ndifferent sequences of phases occurs near the exponent $n=12$. The results are\napplicable to electro- and magnetorheological fluids. In addition to the exact\nground state analysis we study freezing of the Stockmayer fluid by\ndensity-functional theory."
    },
    {
        "anchor": "Self-consistent scattering theory of the pair distribution function in\n  charged Bose fluids: We use a density functional theoretical approach to calculate the pair\ndistribution function and the effective interactions in homogeneous fluids of\nspinless charged bosons. The scheme involves the self-consistent solution of a\ntwo-particle scattering problem with an effective scattering potential which\nembodies many-body effects and is adjusted to the compressibility sum rule.\nNumerical results are presented over an extensive range of density in both\nthree and two dimensions.",
        "positive": "Semiflexible polymers in a random environment: We present using simple scaling arguments and one step replica symmetry\nbreaking a theory for the localization of semiflexible polymers in a quenched\nrandom environment. In contrast to completely flexible polymers, localization\nof semiflexible polymers depends not only on the details of the disorder but\nalso on the ease with which polymers can bend. The interplay of these two\neffects can lead to the delocalization of a localized polymer with an increase\nin either the disorder density or the stiffness. Our theory provides a general\ncriterion for the delocalization of polymers with varying degrees of\nflexibility and allows us to propose a phase diagram for the highly folded\n(localized) states of semiflexible polymers as a function of the disorder\nstrength and chain rigidity."
    },
    {
        "anchor": "Transition from Susceptible-Infected to Susceptible-Infected-Recovered\n  Dynamics in a Susceptible-Cleric-Zombie-Recovered Active Matter Model: The Susceptible-Infected (SI) and Susceptible-Infected-Recovered (SIR) models\nprovide two distinct representations of epidemic evolution, distinguished by\nthe lack of spontaneous recovery in the SI model. Here we introduce a new\nactive matter epidemic model, the ``Susceptible-Cleric-Zombie-Recovered''\n(SCZR) model, in which spontaneous recovery is absent but zombies can recover\nwith probability $\\gamma$ via interaction with a cleric. Upon interacting with\na zombie, both susceptibles and clerics can enter the zombie state with\nprobability $\\beta$ and $\\alpha$, respectively. By changing the intial fraction\nof clerics or their healing ability rate $\\gamma$, we can tune the SCZR model\nbetween SI dynamics, in which no susceptibles or clerics remain at long times,\nand SIR dynamics, in which no zombies remain at long times. The model is\nrelevant to certain real world diseases such as HIV where spontaneous recovery\nis impossible but where medical interventions by a limited number of caregivers\ncan reduce or eliminate the spread of infection.",
        "positive": "Theoretical and Experimental Study of Compression Effects on Structural\n  Relaxation of Glass-Forming Liquids: We develop the elastically collective nonlinear Langevin equation theory of\nbulk relaxation of glass-forming liquids to investigate molecular mobility\nunder compression conditions. The applied pressure restricts more molecular\nmotion and therefore significantly slows-down the molecular dynamics when\nincreasing the pressure. We quantitatively determine the temperature and\npressure dependence of the structural relaxation time. To validate our model,\ndielectric spectroscopy experiments for three rigid and non-polymeric\nsupramolecules are carried out at ambient and elevated pressures. The numerical\nresults quantitatively agree with experimental data."
    },
    {
        "anchor": "Better stability with measurement errors: Often it is desirable to stabilize a system around an optimal state. This can\nbe effectively accomplished using feedback control, where the system deviation\nfrom the desired state is measured in order to determine the magnitude of the\nrestoring force to be applied. Contrary to conventional wisdom, i.e. that a\nmore precise measurement is expected to improve the system stability, here we\ndemonstrate that a certain degree of measurement error can improve the system\nstability. We exemplify the implications of this finding with numerical\nexamples drawn from various fields, such as the operation of a temperature\ncontroller, the confinement of a microscopic particle, the localization of a\ntarget by a microswimmer, and the control of a population.",
        "positive": "Depletion attraction favors the elastic response of emulsions flowing in\n  a constriction: We study the elasto-plastic behavior of dense attractive emulsions under\nmechanical perturbation. The attraction is introduced through non-specific\ndepletion interactions between the droplets and is controlled by changing the\nconcentration of surfactant micelles in the continuous phase. We find that such\nattractive forces are not sufficient to induce any measurable modification on\nthe scalings between the local packing fraction and the deformation of the\ndroplets. However, when the emulsions are flown through 2D microfluidic\nconstrictions, we uncover a measurable effect of attraction on their\nelasto-plastic response. Indeed, we measure higher levels of deformation inside\nthe constriction for attractive droplets. In addition, we show that these\nmeasurements correlate with droplet rearrangements that are spatially delayed\nin the constriction for higher attraction forces."
    },
    {
        "anchor": "Non-monotoic fluctuation-induced interactions between dielectric slabs\n  carrying charge disorder: We investigate the effect of monopolar charge disorder on the classical\nfluctuation-induced interactions between randomly charged net-neutral\ndielectric slabs and discuss various generalizations of recent results (A. Naji\net al., Phys. Rev. Lett. 104, 060601 (2010)) to highly inhomogeneous dielectric\nsystems with and without statistical disorder correlations. We shall focus on\nthe specific case of two generally dissimilar plane-parallel slabs, which\ninteract across vacuum or an arbitrary intervening dielectric medium. Monopolar\ncharge disorder is considered to be present on the bounding surfaces and/or in\nthe bulk of the slabs, may be in general quenched or annealed and may possess a\nfinite lateral correlation length reflecting possible `patchiness' of the\nrandom charge distribution. In the case of quenched disorder, the bulk disorder\nis shown to give rise to an additive long-range contribution to the total\nforce, which decays as the inverse distance between the slabs and may be\nattractive or repulsive depending on the dielectric constants of the slabs. We\nshow that in the case of two dissimilar slabs the net effect due to the\ninterplay between the disorder-induced and the pure van der Waals interactions\ncan lead to a variety of unusual non-monotonic interaction profiles between the\ndielectric slabs. In particular, when the intervening medium has a larger\ndielectric constant than the two slabs, we find that the net interaction can\nbecome repulsive and exhibit a potential barrier, while the underlying van der\nWaals force is attractive. On the contrary, when the intervening medium has a\ndielectric constant in between that of the two slabs, the net interaction can\nbecome attractive and exhibit a free energy minimum, while the pure van der\nWaals force is repulsive. Therefore, the charge disorder, if present, can\ndrastically alter the effective interaction between net-neutral objects.",
        "positive": "Solvation Effects on Free Energy Surface of Polyalanine: We have simulated 10-residue polyalanine chain by multicanonical method to\nvisualize the 3D topographic picture of the free energy landscape over the\nwhole range of temperatures, hence to show the funnel along the folding pathway\nexhaustively. We have simulated and compared the system in vacuo and in\nsolvent, and examined the changes in the free energy landscape due to the\nsolvent effects, which are taken into account by commonly used model Accessible\nSurface Area."
    },
    {
        "anchor": "Force Unfolding Single RNAs: from Equilibrium to Far-from Equilibrium: We summarize the recent simulation progress of micromanipulation experiments\non RNAs. Our work mainly consults with two important small RNAs unfolding\nexperiments carried out by Bustamante group. Our results show that, in contrast\nto protein cases, using the single polymer elastic theory and the well known\nRNA secondary structure free energy knowledge, we can successively simulate\nvarious behaviors of force unfolding RNAs under different experimental setups\nfrom equilibrium to far-from equilibrium. Particularly, our simulation would be\nhelpful in understanding Jarzynski's remarkable equality, which its\nexperimental test has received considerable attention.",
        "positive": "Adsorption of multivalent ions on a charged surface: Oscillating\n  inversion of charge: Adsorption of multivalent counterions on the charged surface of a macroion is\nknown to lead to inversion of the macroion charge due to the strong lateral\ncorrelations of counterions. We consider a nontrivial role of the excluded\nvolume of counterions on this effect. It is shown analytically that when the\nbare charge of macroion increases, its net charge including the adsorbed\ncounterions oscillates with the number of their layers. Charge inversion\nvanishes every time the top layer of counterions is completely full and becomes\nincompressible. These oscillations of charge inversion are confirmed by\nMonte-Carlo simulations. Another version of this phenomenon is studied for a\nmetallic electrode screened by multivalent counterions when potential of the\nelectrode is controlled instead of its charge. In this case, oscillations of\nthe compressibility and charge inversion lead to oscillations of capacitance of\nthis electrode with the number of adsorbed layers of multivalent counterions."
    },
    {
        "anchor": "Intra-chain correlation functions and shapes of homopolymers with\n  different architectures in dilute solution: We present results of Monte Carlo study of the monomer-monomer correlation\nfunctions, static structure factor and asphericity characteristics of a single\nhomopolymer in the coil and globular states for three distinct architectures of\nthe chain: ring, open and star. To rationalise the results we introduce the\ndimensionless correlation functions rescaled via the corresponding mean-squared\ndistances between monomers. For flexible chains with some architectures these\nfunctions exhibit a large degree of universality by falling onto a single or\nseveral distinct master curves. In the repulsive regime, where a stretched\nexponential times a power law form (de Cloizeaux scaling) can be applied, the\ncorresponding exponents $\\delta$ and $\\theta$ have been obtained. The exponent\n$\\delta=1/\\nu$ is found to be universal for flexible strongly repulsive coils\nand in agreement with the theoretical prediction from improved higher-order\nBorel-resummed renormalisation group calculations. The short-distance exponents\n$\\theta_{\\upsilon}$ of an open flexible chain are in a good agreement with the\ntheoretical predictions in the strongly repulsive regime also. However,\nincreasing the Kuhn length in relation to the monomer size leads to their fast\ncross-over towards the Gaussian behaviour. Likewise, a strong sensitivity of\nvarious exponents $\\theta_{ij}$ on the stiffness of the chain, or on the number\nof arms in star polymers, is observed. The correlation functions in the\nglobular state are found to have a more complicated oscillating behaviour and\ntheir degree of universality has been reviewed. Average shapes of the polymers\nin terms of the asphericity characteristics, as well as the universal behaviour\nin the static structure factors, have been also investigated.",
        "positive": "Crystallization of Crystalline/Crystalline Symmetric Polymer Blends\n  Studied by Dynamic Monte Carlo Simulations: In this paper, we report dynamic Monte Carlo simulation results on the\ncrystallization of crystalline/crystalline (A/B) symmetric binary polymer\nblend, wherein the melting temperature of A-polymer is higher than B-polymer.\nCrystallization of A-polymer precedes the crystallization of B-polymer upon\ncooling from a homogeneous melt. The morphological development is controlled by\nthe interplay between crystallization and macrophase separation. With\nincreasing segregation strength, smaller and thinner crystals form with lesser\ncrystallinity. During the process, A-polymer crystallizes first followed by the\ncrystallization of B-polymer in the presence of already crystalline domains\nA-polymer. Thus, crystallization of B-polymer slows down influencing overall\ncrystal morphology. With increasing segregation strength between two polymers,\nwe observe a decreasing trend in mean square radius of gyration, reflecting the\nincreased repulsive interaction between them. As a consequence, a large number\nof smaller size crystals form with lesser crystallinity. Isothermal\ncrystallization reveals that the transition pathways strongly depend on\nsegregation strength. We also observe a path-dependent crystallization behavior\nin isothermal crystallization: two-step (sequential) isothermal crystallization\nyields superior crystalline structure in both A- and B-polymers than one-step\n(coincident)."
    },
    {
        "anchor": "Suppression of bacterial rheotaxis in wavy channels: Controlling the swimming behavior of bacteria is crucial, for example, to\nprevent contamination of ducts and catheters. We show the bacteria modeled by\ndeformable microswimmers can accumulate in flows through straight microchannels\neither in their center or on previously unknown attractors near the channel\nwalls. We predict a novel resonance effect for semiflexible microswimmers in\nflows through wavy microchannels. As a result, microswimmers can be deflected\nin a controlled manner so that they swim in modulated channels distributed over\nthe channel cross-section rather than localized near the wall or the channel\ncenter.\n  Thus, depending on the flow amplitude, both upstream orientation of swimmers\nand their accumulation at the boundaries which can lead to surface rheotaxis\nare suppressed. Our results suggest new strategies for controlling the behavior\nof live and synthetic swimmers in microchannels.",
        "positive": "Force-induced breakdown of flexible polymerized membrane: We consider the fracture of a free-standing two-dimensional (2D)\nelastic-brittle network to be used as protective coating subject to constant\ntensile stress applied on its rim. Using a Molecular Dynamics simulation with\nLangevin thermostat, we investigate the scission and recombination of bonds,\nand the formation of cracks in the 2D graphene-like hexagonal sheet for\ndifferent pulling force $f$ and temperature $T$. We find that bond rupture\noccurs almost always at the sheet periphery and the First Mean Breakage Time\n$<\\tau>$ of bonds decays with membrane size as $<\\tau> \\propto N^{-\\beta}$\nwhere $\\beta \\approx 0.50\\pm 0.03$ and $N$ denotes the number of atoms in the\nmembrane. The probability distribution of bond scission times $t$ is given by a\nPoisson function $W(t) \\propto t^{1/3} \\exp (-t / <\\tau>)$. The mean failure\ntime $<\\tau_r>$ that takes to rip-off the sheet declines with growing size $N$\nas a power law $<\\tau_r> \\propto N^{-\\phi(f)}$. We also find $<\\tau_r> \\propto\n\\exp(\\Delta U_0/k_BT)$ where the nucleation barrier for crack formation $\\Delta\nU_0 \\propto f^{-2}$, in agreement with Griffith's theory. $<\\tau_r>$ displays\nan Arrhenian dependence of $<\\tau_r>$ on temperature $T$. Our results indicate\na rapid increase in crack spreading velocity with growing external tension $f$."
    },
    {
        "anchor": "Orientational order and glassy states in networks of semiflexible\n  polymers: Motivated by the structure of networks of cross-linked cytoskeletal\nbiopolymers, we study the orientationally ordered phases in two-dimensional\nnetworks of randomly cross-linked semiflexible polymers. We consider permanent\ncross-links which prescribe a finite angle and treat them as quenched disorder\nin a semi-microscopic replica field theory. Starting from a fluid of\nun-cross-linked polymers and small polymer clusters (sol) and increasing the\ncross-link density, a continuous gelation transition occurs. In the resulting\ngel, the semiflexible chains either display long range orientational order or\nare frozen in random directions depending on the value of the crossing angle,\nthe crosslink concentration and the stiffness of the polymers. A crossing angle\n$\\theta\\sim 2\\pi/M$ leads to long range $M$-fold orientational order, e.g.,\n\"hexatic\" or \"tetratic\" for $\\theta=60^{\\circ}$ or $90^{\\circ}$, respectively.\nThe transition is discontinuous and the critical cross-link density depends on\nthe bending stiffness of the polymers and the cross-link geometry: the higher\nthe stiffness and the lower $M$, the lower the critical number of cross-links.\nIn between the sol and the long range ordered state, we always observe a gel\nwhich is a statistically isotropic amorphous solid (SIAS) with random\npositional and random orientational localization of the participating polymers.",
        "positive": "1D Classical Density Functional Theory of a Tethered Polymer Layer: A simple application of classical density functional theory is derived and\napplied to a system of polymers grafted to a plane. The system is assumed to\nhave symmetry in directions parallel to the grafting plane hence it being a\n'1-dimensional' problem. A quick introduction to using propagators in the\ntheory of chains in the presence of external fields and a numerical algorithm\nfor solving the modified diffusion (or Fokker-Planck) equation are presented.\nDensity profiles are found for hard-sphere chains which agree with results in\nthe literature (see Murat,.., Milner,.., Muhukumar and others) and align with\nphysical expectations of brush formation due to excluded volume. The linear\nscaling $h \\approx (\\sigma)^{1/3} N$, of brush height with polymerisation $N$,\nis reproduced here."
    },
    {
        "anchor": "Stabilization of nonlinear velocity profiles in athermal systems\n  undergoing planar shear flow: We perform molecular dynamics simulations of model granular systems\nundergoing boundary-driven planar shear flow in two spatial dimensions with the\ngoal of developing a more complete understanding of how dense particulate\nsystems respond to applied shear. In particular, we are interested in\ndetermining when these systems will possess linear velocity profiles and when\nthey will develop highly localized velocity profiles in response to shear. In\nprevious work on similar systems we showed that nonlinear velocity profiles\nform when the speed of the shearing boundary exceeds the speed of shear waves\nin the material. However, we find that nonlinear velocity profiles in these\nsystems are unstable at very long times. The degree of nonlinearity slowly\ndecreases in time; the velocity profiles become linear when the granular\ntemperature and density profiles are uniform across the system at long times.\nWe measure the time $t_l$ required for the velocity profiles to become linear\nand find that $t_l$ increases as a power-law with the speed of the shearing\nboundary and increases rapidly as the packing fraction approaches random close\npacking. We also performed simulations in which differences in the granular\ntemperature across the system were maintained by vertically vibrating one of\nthe boundaries during shear flow. We find that nonlinear velocity profiles form\nand are stable at long times if the difference in the granular temperature\nacross the system exceeds a threshold value that is comparable to the glass\ntransition temperature in an equilibrium system at the same average density.\nFinally, the sheared and vibrated systems form stable shear bands, or highly\nlocalized velocity profiles, when the applied shear stress is lowered below the\nyield stress of the static part of the system.",
        "positive": "Influence of Elastic Strains on the Adsorption Process in Porous\n  Materials. An Experimental Approach: The experimental results presented in this paper show the influence of the\nelastic deformation of porous solids on the adsorption process. With p+-type\nporous silicon formed on highly boron doped (100) Si single crystal, we can\nmake identical porous layers, either supported by or detached from the\nsubstrate. The pores are perpendicular to the substrate. The adsorption\nisotherms corresponding to these two layers are distinct. In the region\npreceding capillary condensation, the adsorbed amount is lower for the membrane\nthan for the supported layer and the hysteresis loop is observed at higher\npressure. We attribute this phenomenon to different elastic strains undergone\nby the two layers during the adsorption process. For the supported layer, the\nplanes perpendicular to the substrate are constrained to have the same\ninteratomic spacing as that of the substrate so that the elastic deformation is\nunilateral, at an atomic scale, and along the pore axis. When the substrate is\nremoved, tridimensional deformations occur and the porous system can find a new\nconfiguration for the solid atoms which decreases the free energy of the system\nadsorbate-solid. This results in a decrease of the adsorbed amount and in an\nincrease of the condensation pressure. The isotherms for the supported porous\nlayers shift toward that of the membrane when the layer thickness is increased\nfrom 30 to 100 microns. This is due to the relaxation of the stress exerted by\nthe substrate as a result of the breaking of Si-Si bonds at the interface\nbetween the substrate and the porous layer. The membrane is the relaxed state\nof the supported layer."
    },
    {
        "anchor": "A predictive model for the thermomechanical overstretching transition of\n  double stranded DNA: By extending the classical Peyrard-Bishop model, we are able to obtain a\nfully analytical description for the mechanical resistance of DNA under\nstretching at variable values of temperature, number of base pairs and\nintrachains and interchains bonds stiffness. In order to compare elasticity and\ntemperature effects, we first analyze the system in the zero temperature\nmechanical limit, important to describe several experimental effects including\npossible hysteresis. We then analyze temperature effects in the framework of\nequilibrium statistical mechanics. In particular, we obtain an analytical\nexpression for the temperature dependent melting force and unzipping assigned\ndisplacement in the thermodynamical limit, also depending on the relative\nstability of intra vs inter molecular bonds. Such results coincide with the\npurely mechanical model in the limit of zero temperature and with the\ndenaturation temperature that we obtain with the classical transfer integral\nmethod. Based on our analytical results, explicit analysis of the phase\ndiagrams and cooperativity parameters are obtained, where also discreteness\neffect can be accounted for. The obtained results are successfully applied in\nreproducing the thermomechanical experimental melting of DNA and the response\nof DNA hairpins. Due to its generality, the proposed approach can be extended\nto other thermomechanically induced molecular melting phenomena.",
        "positive": "Replica theory of the rigidity of structural glasses: We present a first principle scheme to compute the rigidity, i. e. the\nshear-modulus of structural glasses at finite temperatures using the cloned\nliquid theory, which combines the replica theory and the liquid theory. With\nthe aid of the replica method which enables disentanglement of thermal\nfluctuations in liquids into intra-state and inter-state fluctuations, we\nextract the rigidity of metastable amorphous solid states in the supercooled\nliquid and glass phases. The result can be understood intuitively without\nreplicas. As a test case, we apply the scheme to the supercooled and glassy\nstate of a binary mixture of soft-spheres. The result compares well with the\nshear-modulus obtained by a previous molecular dynamic simulation. The rigidity\nof metastable states is significantly reduced with respect to the instantaneous\nrigidity, namely the Born term, due to non-affine responses caused by\ndisplacements of particles inside cages at all temperatures down to T=0. It\nbecomes nearly independent of temperature below the Kauzmann temperature T_K.\nAt higher temperatures in the supercooled liquid state, the non-affine\ncorrection to the rigidity becomes stronger suggesting melting of the\nmetastable solid state. Inter-state part of the static response implies jerky,\nintermittent stress-strain curves with static analogue of yielding at\nmesoscopic scales."
    },
    {
        "anchor": "Which glass stability parameters can assess the glass-forming ability of\n  oxide systems?: Glass forming ability (GFA) is a property of utmost importance in glass\nscience and technology. In this paper, we used a statistical\nmethodology---involving bootstrap sampling and the Wilcoxon test---to find out\nwhich glass stability parameters can better predict the glass forming ability.\nWe collected or measured the necessary data for twelve stoichiometric oxide\nglasses that underwent predominant heterogeneous nucleation (the most common\ncase). We found that some GS parameters could predict the GFA of these oxide\nglasses quite well, whereas others perform poorly. Parameter $K_w$ was the top\nranked, closely followed by the $K_H$, $\\gamma$, $H^{'}$, $\\Delta T_{rg}$, and\n$K_{cr}$. Our results corroborate previous reports carried out using a smaller\nnumber of glasses, much less GS parameters, and less rigorous statistics. We\nalso found that using $T_c$ instead of $T_x$ improved the predictive power of\nthese parameters. Finally, the Jezica, the only parameter considered here that\npredicts the GFA without requiring the production of a glass piece (i.e.,\nwithout relying on any crystallization information), ranked reasonably well in\nour analysis.",
        "positive": "Theory of the Jamming Transition at Finite Temperature: A theory for the microscopic structure and the vibrational properties of soft\nsphere glass at finite temperature is presented. With an effective potential,\nderived here, the phase diagram and vibrational properties are worked out\naround the Maxwell critical point at zero temperature $T$ and pressure $p$.\nVariational arguments and effective medium theory identically predict a\nnon-trivial temperature scale $T^*\\sim p^{(2-a)/(1-a)}$ with $a \\approx 0.17$\nsuch that low-energy vibrational properties are hard-sphere like for $T \\gtrsim\nT^*$, and zero-temperature soft-sphere like otherwise. However, due to\ncrossovers in the equation of state relating $T$, $p$, and the packing fraction\n$\\phi$, these two regimes lead to four regions where scaling behaviors differ\nwhen expressed in terms of $T$ and $\\phi$. Scaling predictions are presented\nfor the mean-squared displacement, characteristic frequency, shear modulus, and\ncharacteristic elastic length in all regions of the phase diagram."
    },
    {
        "anchor": "The Charge of Glass and Silica Surfaces: We present a method of calculating the electric charge density of glass and\nsilica surfaces in contact with aqueous electrolytes for two cases of practical\nrelevance that are not amenable to standard techniques: surfaces of low\nspecific area at low ionic strength and surfaces interacting strongly with a\nsecond anionic surface.",
        "positive": "Refraction of shear zones in granular materials: We study strain localization in slow shear flow focusing on layered granular\nmaterials. A heretofore unknown effect is presented here. We show that shear\nzones are refracted at material interfaces in analogy with refraction of light\nbeams in optics. This phenomenon can be obtained as a consequence of a recent\nvariational model of shear zones. The predictions of the model are tested and\nconfirmed by 3D discrete element simulations. We found that shear zones follow\nSnell's law of light refraction."
    },
    {
        "anchor": "Externally driven local colloidal ordering induced by a point-like heat\n  source: We study here how phase transitions are induced in colloidal suspensions by a\npoint-like heat source, an optically trapped metal oxide particle absorbing\nlight. We find that thermophoresis increases the number density of colloids\naround the oxide particle, leading to the appearance of solid clusters. Our\nanalysis based on thermophoresis reveals that the solid-fluid interface\nposition is purely determined by the relationship of the particle concentration\nprofile in the fluid state with the volume fraction of the phase transition,\nand no other effect of thermodynamics is seen in the cluster sizes. In this\nsystem, we observe the formation of face-centered cubic crystals, amorphous\nstates, and structures with icosahedral order. This shows a rich possibility of\nnon-trivial orderings under spatially controlled heterogeneous growth in\nexternal \"semi-soft\" potentials that are softer than walls but with substantial\nvariations at the scale of a few particle diameters. Because of the tuneable\nrate of addition of particles to the clusters, we propose this method could be\nused to study the complex interplay of densification with local spatial\nconfinement effects, kinetics, and ordering.",
        "positive": "Surface Nanobubbles: Theory, Simulation, and Experiment. A Review: Surface nanobubbles (NBs) are stable gaseous phases in liquids that form at\nthe interface with solid substrates. They have been particularly intriguing for\ntheir high stability that contradicts theoretical expectations and their\npotential relevance for many technological applications. Here, we present the\ncurrent state of the art in this research area by discussing and contrasting\nmain results obtained from theory, simulation and experiment, and presenting\ntheir limitations. We also provide future perspectives anticipating that this\nreview will stimulate further studies in the research area of surface NBs."
    },
    {
        "anchor": "An elasto-plastic approach based on microscopic insights for the steady\n  state and transient dynamics of sheared disordered solids: In this letter, we develop a framework to study the mechanical response of\nathermal amorphous solids via a coupling of mesoscale and microscopic models.\nUsing measurements of coarse grained quantities from simulations of dense\ndisordered particulate systems, we present a coherent elasto-plastic model\napproach for deformation and flow of yield stress materials. For a given set of\nparameters, this model allows to match consistently transient and steady state\nfeatures of driven disordered systems under both applied shear-rate and creep\nprotocols.",
        "positive": "Crack and pull-off dynamics of adhesive, viscoelastic solids: When quickly detaching an elastomer from a counterface, viscoelasticity\ndramatically increases the perceived adhesion relative to its adiabatic or\nequilibrium value. Here, we report simulations on the sticking contact between\na rigid cylinder and a viscoelastic half space revealing a maximum in the work\nof adhesion at intermediate pull-off velocities. Maximum tensile forces yet\nincrease monotonically with the pull-off speed and the crack-tip speed in\naccordance with the Persson-Brener approach. As predicted theoretically, the\nfracture mode transitions from interfacial crack propagation to quasi-uniform\nbond breaking with increasing range of adhesion."
    },
    {
        "anchor": "Surface alignment and anchoring transitions in nematic lyotropic\n  chromonic liquid crystal: The surface alignment of lyotropic chromonic liquid crystals (LCLCs) can be\nnot only planar (tangential) but also homeotropic, with self-assembled\naggregates perpendicular to the substrate, as demonstrated by mapping optical\nretardation and by three-dimensional imaging of the director field. With time,\nthe homeotropic nematic undergoes a transition into a tangential state. The\nanchoring transition is discontinuous and can be described by a double-well\nanchoring potential with two minima corresponding to tangential and homeotropic\norientation.",
        "positive": "Collective entrainment and confinement amplify transport by schooling\n  micro-swimmers: Micro-swimmers can serve as cargo carriers that move deep inside complex flow\nnetworks. When a school collectively entrains the surrounding fluid, their\ntransport capacity can be enhanced. This effect is quantified with good\nagreement between experiments with self-propelled droplets and a confined\nBrinkman squirmer model. The volume of liquid entrained can be much larger than\nthe droplet itself, amplifying the effective cargo capacity over an order of\nmagnitude, even for dilute schools. Hence, biological and engineered swimmers\ncan efficiently transport materials into confined environments."
    },
    {
        "anchor": "Future Directions for Active Matter on Ordered Substrates: Active matter is a term encompassing particle-based assemblies with some form\nof self-propulsion, including certain biological systems as well as synthetic\nsystems such as artificial colloidal swimmers, all of which can exhibit a\nremarkable variety of new kinds of nonequilibrium phenomena. A wealth of\nnon-active condensed matter systems can be described in terms of a collection\nof particles coupled to periodic substrates, leading to the emergence of\ncommensurate-incommensurate effects, Mott phases, tribology effects, and\npattern formation. It is natural to ask how such phases are modified when the\nsystem is active. Here we provide an overview and future directions for\nstudying individual and collectively interacting active matter particles\ncoupled to periodic substrates, where new types of commensuration effects,\ndirectional locking, and active phases can occur. Further directions for\nexploration include locking effects, the realization of active solitons or\nactive defects in incommensurate phases, active Mott phases, active artificial\nspin ice, active doping transitions, active floating phases, active surface\nphysics, active matter time crystals, and active tribology.",
        "positive": "Atomistic structural mechanism for the glass transition: Entropic\n  contribution: A popular Adam--Gibbs scenario has suggested that the excess entropy of glass\nand liquid over crystal dominates the dynamical arrest at the glass transition\nwith exclusive contribution from configurational entropy over vibrational\nentropy. However, an intuitive structural rationale for the emergence of frozen\ndynamics in relation to entropy is still lacking. Here we study these issues by\natomistically simulating the vibrational, configurational, as well as total\nentropy of a model glass former over their crystalline counterparts for the\nentire temperature range spanning from glass to liquid. Besides confirming the\nAdam--Gibbs entropy scenario, the concept of Shannon information entropy is\nintroduced to characterize the diversity of atomic-level structures, which\nundergoes a striking variation across the glass transition, and explains the\nchange found in the excess configurational entropy. Hence, the hidden\nstructural mechanism underlying the entropic kink at the transition is revealed\nin terms of proliferation of certain atomic structures with a higher degree of\ncentrosymmetry, which are more rigid and possess less nonaffine softening\nmodes. In turn, the proliferation of these centrosymmetric (rigid) structures\nleads to the freezing-in of the dynamics beyond which further structural\nrearrangements become highly unfavourable, thus explaining the kink in the\nconfigurational entropy at the transition."
    },
    {
        "anchor": "The Geometry of Optimal Gaits for Inertia-dominated Kinematic Systems: Isolated mechanical systems -- e.g., those floating in space, in free-fall,\nor on a frictionless surface -- are able to achieve net rotation by cyclically\nchanging their shape, even if they have no net angular momentum. Similarly,\nswimmers immersed in \"perfect fluids\" are able to use cyclic shape changes to\nboth translate and rotate even if the swimmer-fluid system has no net linear or\nangular momentum. Finally, systems fully constrained by direct nonholonomic\nconstraints (e.g., passive wheels) can push against these constraints to move\nthrough the world. Previous work has demonstrated that the net displacement\ninduced by these shape changes corresponds to the amount of *constraint\ncurvature* that the gaits enclose.\n  To properly assess or optimize the utility of a gait, however, we must also\nconsider the time or resources required to execute it: A gait that produces a\nsmall displacement per cycle, but that can be executed in a short time, may\nproduce a faster average velocity than a gait that produces a large\ndisplacement per cycle, but takes much longer to complete a cycle at the same\naverage instantaneous effort.\n  In this paper, we consider two effort-based cost functions for assessing the\ncosts associated with executing these cycles. For each of these cost functions,\nwe demonstrate that fixing the average instantaneous cost to a unit value\nallows us to transform the effort costs into time-to-execute costs for any\ngiven gait cycle. We then illustrate how the interaction between the constraint\ncurvature and these costs leads to characteristic geometries for optimal\ncycles, in which the gait trajectories resemble elastic hoops distended from\nwithin by internal pressures.",
        "positive": "Shear-induced diffusion in non-local granular flows: We investigate the properties of self-diffusion in heterogeneous dense\ngranular flows involving a gradient of stress and inertial number. The study is\nbased on simulated plane shear with gravity and Poiseuille flows, in which\nnon-local effects induce some creep flow in zones where stresses are below the\nyield. Results show that shear-induced diffusion is qualitatively different in\nzones above and below the yield. Below the yield, diffusivity is no longer\ngoverned by velocity fluctuations, and we evidenced a direct scaling between\ndiffusivity and local shear rate. This is interpreted by analysing the grain\ntrajectories, which exhibit a caging dynamics developing in zones below the\nyield. We finally introduce an explicit scaling for the profile of local\ninertial number in these zones, which leads to a straightforward expression of\nthe diffusivity as a function of the stress and position in non-local flows."
    },
    {
        "anchor": "Viscous fingering in liquid crystals: Anisotropy and morphological\n  transitions: We show that a minimal model for viscous fingering with a nematic liquid\ncrystal in which anisotropy is considered to enter through two different\nviscosities in two perpendicular directions can be mapped to a two-fold\nanisotropy in the surface tension. We numerically integrate the dynamics of the\nresulting problem with the phase-field approach to find and characterize a\ntransition between tip-splitting and side-branching as a function of both\nanisotropy and dimensionless surface tension. This anisotropy dependence could\nexplain the experimentally observed (reentrant) transition as temperature and\napplied pressure are varied. Our observations are also consistent with previous\nexperimental evidence in viscous fingering within an etched cell and\nsimulations of solidification.",
        "positive": "A comparison of classical interatomic potentials applied to highly\n  concentrated aqueous lithium chloride solutions: Aqueous lithium chloride solutions up to very high concentrations were\ninvestigated in classical molecular dynamics simulations. Various force fields\nbased on the 12-6 Lennard-Jones model, parametrized for non-polarizable water\nsolvent molecules (SPC/E, TIP4P, TIP4PEw), were inspected. Twenty-nine\ncombinations of ion-water interaction models were examined at four different\nsalt concentrations. Densities, static dielectric constants and self-diffusion\ncoefficients were calculated. Results derived from the different force fields\nscatter over a wide range of values. Neutron and X-ray weighted structure\nfactors were also calculated from the radial distribution functions and\ncompared with experimental data. It was found that the agreement between\ncalculated and experimental curves is rather poor for several investigated\npotential models, even though some of them have previously been applied in\ncomputer simulations. None of the investigated models yield satisfactory\nresults for all the tested quantities. Only two parameter sets provide\nacceptable predictions for the structure of highly concentrated aqueous LiCl\nsolutions. Some approaches for adjusting potential parameters, such as those of\nAragones [Aragones et al., J. Phys. Chem. B 118 (2014) 7680] and Pluharova\n[Pluharova et al, J. Phys. Chem. A 117 (2013) 11766], were tested as well; the\nsimulations presented here underline their usefulness. These refining methods\nare suited to obtain more appropriate ion/water potentials."
    },
    {
        "anchor": "Surface induced structures in nematic liquid crystal colloids: We predict theoretically the existence of a class of colloidal structures in\nnematic liquid crystal (NLC) cells, which are induced by surface patterns on\nthe plates of the cell (like cells with UV-irradiated polyimide surfaces using\nmicron size masks). These bulk structures arise from non-zero boundary\nconditions for the director distortions at the confining surfaces. In\nparticular, we demonstrate that quadrupole spherical particles (like spheres\nwith boojums or Saturn-ring director configurations) form a square lattice\ninside a planar NLC cell, which has checkerboard patterns on both its plates.",
        "positive": "Effect of chain length on fragility and thermodynamic scaling of the\n  local segmental dynamics in poly(methylmethacrylate): Local segmental relaxation properties of poly(methylmethacrylate) (PMMA) of\nvarying molecular weight are measured by dielectric spectroscopy, and analyzed\nin combination the equation of state obtained from PVT measurements. The usual\nvariation of glass transition temperature and fragility with molecular weight\nare observed. We also find, in accord with the general properties of\nglass-forming materials, that a single molecular weight dependent scaling\nexponent, g, is sufficient to define the mean segmental relaxation time,\ntau_alpha, and its distribution. This exponent can be connected to the\nGruneisen parameter and related thermodynamic quantities, thus demonstrating\nthe interrelationship between dynamics and thermodynamics in PMMA. Changes in\nthe relaxation properties (\"dynamic crossover\") are observed as a function of\nboth temperature and pressure, with tau_alpha serving as the control parameter\nfor the crossover. At longer tau_alpha another change in the dynamics is\napparent, associated with a decoupling of the local segmental process from\nionic conductivity."
    },
    {
        "anchor": "To grow or to shrink: A tale of two rubber balloons: Two identical rubber balloons are partially inflated with air (to different\nextent) and connected by a hose with a valve. It is found that depending on\nballoon volumes, when the valve is opened the air will flow either from the\nlarger (fuller) balloon to the smaller (emptier) balloon, or from the smaller\nballoon to the larger one. The phenomenon is explained in terms of the\nnon-ideal rubber elasticity of balloons. The full phase diagram for the air\nflow dynamics is constructed.",
        "positive": "Duality,Hidden Symmetry and Dynamic Isomerism in 2D Hinge Structures: Recently, a new type of duality was reported in some deformable mechanical\nnetworks which exhibit Kramers-like degeneracy in phononic spectrum at the\nself-dual point. In this work, we clarify the origin of this duality and\npropose a design principle of 2D self-dual structures with arbitrary\ncomplexity. We find that this duality originates from the (PCI) symmetry of the\nhinge, which belongs to a more general end-fixed scaling transformation. This\nsymmetry gives the structure an extra degree of freedom without modifying its\ndynamics. This results in , i.e., dissimilar 2D mechanical structures, either\nperiodic or aperiodic, having identical dynamic modes, based on which we\ndemonstrate a new type of wave-guide without reflection or loss. Moreover, the\nPCI symmetry allows us to design various 2D periodic isostatic networks with\nhinge duality. At last, by further studying a 2D non-mechanical magnonic\nsystem, we show that the duality and the associated hidden symmetry should\nexist in a broad range of Hamiltonian systems."
    },
    {
        "anchor": "Reorientational relaxation of a linear probe molecule in a simple glassy\n  liquid: Within the mode-coupling theory (MCT) for the evolution of structural\nrelaxation in glass-forming liquids, correlation functions and susceptibility\nspectra are calculated characterizing the rotational dynamics of a top-down\nsymmetric dumbbell molecule, consisting of two fused hard spheres immersed in a\nhard-sphere system. It is found that for sufficiently large dumbbell\nelongations, the dynamics of the probe molecule follows the same universal\nglass-transition scenario as known from the MCT results of simple liquids. The\n$\\alpha$-relaxation process of the angular-index-j=1 response is stronger,\nslower and less stretched than the one for j=2, in qualitative agreement with\nresults found by dielectric-loss and depolarized-light-scattering spectroscopy\nfor some supercooled liquids. For sufficiently small elongations, the\nreorientational relaxation occurs via large-angle flips, and the standard\nscenario for the glass-transition dynamics is modified for odd-j responses due\nto precursor phenomena of a nearby type-A MCT transition. In this case, a major\npart of the relaxation outside the transient regime is described qualitatively\nby the $\\beta$-relaxation scaling laws, while the $\\alpha$-relaxation scaling\nlaw is strongly disturbed.",
        "positive": "The role of quench rate in colloidal gels: Interactions between colloidal particles have hitherto usually been fixed by\nthe suspension composition. Recent experimental developments now enable the\ncontrol of interactions \\emph{in-situ}. Here we use Brownian dynamics\nsimulations to investigate the effect of controlling interactions on gelation,\nby \"quenching\" the system from an equilibrium fluid to a gel. We find that,\ncontrary to the normal case of an instantaneous quench, where the local\nstructure of the gel is highly disordered, controlled quenching results in a\ngel with a higher degree of local order. Under sufficiently slow quenching,\nlocal crystallisation is found, which is strongly enhanced when a monodisperse\nsystem is used. The higher the degree of local order, the smaller the mean\nsquared displacement, indicating an enhancement of gel stability."
    },
    {
        "anchor": "Extracting the dynamic correlation length of actin networks from\n  microrheology experiments: The mechanical properties of polymer gels based on cytoskeleton proteins\n(e.g. actin) have been studied extensively due to their significant role in\nbiological cell motility and in maintaining the cell's structural integrity.\nMicrorheology is the natural method of choice for such studies due to its\neconomy in sample volume, its wide frequency range, and its spatial\nsensitivity. In microrheology, the thermal motion of tracer particles embedded\nin a complex fluid is used to extract the fluid's viscoelastic properties.\nComparing the motion of a single particle to the correlated motion of particle\npairs, it is possible to extract viscoelastic properties at different length\nscales. In a recent study, a crossover between intermediate and bulk response\nof complex fluids was discovered in microrheology measurements of reconstituted\nactin networks. This crossover length was related to structural and mechanical\nproperties of the networks, such as their mesh size and dynamic correlation\nlength. Here we capitalize on this result giving a detailed description of our\nanalysis scheme, and demonstrating how this relation can be used to extract the\ndynamic correlation length of a polymer network. We further study the relation\nbetween the dynamic correlation length and the structure of the network, by\nintroducing a new length scale, the average filament length, without altering\nthe network's mesh size. Contrary to the prevailing assumption, that the\ndynamic correlation length is equivalent to the mesh size of the network, we\nfind that the dynamic correlation length increases once the filament length is\nreduced below the crossover distance.",
        "positive": "The Shapes of Cooperatively Rearranging Regions in Glass Forming Liquids: The shapes of cooperatively rearranging regions in glassy liquids change from\nbeing compact at low temperatures to fractal or ``stringy'' as the dynamical\ncrossover temperature from activated to collisional transport is approached\nfrom below. We present a quantitative microscopic treatment of this change of\nmorphology within the framework of the random first order transition theory of\nglasses. We predict a correlation of the ratio of the dynamical crossover\ntemperature to the laboratory glass transition temperature, and the heat\ncapacity discontinuity at the glass transition, Delta C_p. The predicted\ncorrelation agrees with experimental results for the 21 materials compiled by\nNovikov and Sokolov."
    },
    {
        "anchor": "Vorticity Determines the Force on Bodies Immersed in Active Fluids: When immersed into a fluid of active Brownian particles, passive bodies might\nstart to undergo linear or angular directed motion depending on their shape.\nHere we exploit the divergence theorem to relate the forces responsible for\nthis motion to the density and current induced by--but far away from--the body.\nIn general, the force is composed of two contributions: due to the strength of\nthe dipolar field component and due to particles leaving the boundary,\ngenerating a non-vanishing vorticity of the polarization. We derive and\nnumerically corroborate results for periodic systems, which are fundamentally\ndifferent from unbounded systems with forces that scale with the area of the\nsystem. We demonstrate that vorticity is localized close to the body and to\npoints at which the local curvature changes, enabling the rational design of\nparticle shapes with desired propulsion properties.",
        "positive": "On the emergence of orientational order in folded proteins with\n  implications for allostery: The beautiful structures of single and multi-domain proteins are clearly\nordered in some fashion but cannot be readily classified using group theory\nmethods that are successfully used to describe periodic crystals. For this\nreason, protein structures are considered to be aperiodic, and may have evolved\nthis way for functional purposes, especially in instances that require a\ncombination of softness and rigidity within the same molecule. By analyzing the\nsolved protein structures, we show that orientational symmetry is broken in the\naperiodic arrangement of the secondary structural elements (SSEs), which we\ndeduce by calculating the nematic order parameter, $P_{2}$. We find that the\nfolded structures are nematic droplets with a broad distribution of $P_{2}$. We\nargue that non-zero values of $P_{2}$, leads to an arrangement of the SSEs that\ncan resist mechanical forces, which is a requirement for allosteric proteins.\nSuch proteins, which resist mechanical forces in some regions while being\nflexible in others, transmit signals from one region of the protein to another\n(action at a distance) in response to binding of ligands (oxygen, ATP or other\nsmall molecules)."
    },
    {
        "anchor": "Rheological investigation of gels formed by competing interactions: A\n  numerical study: A transition from solid-like to liquid-like behavior occurs when colloidal\ngels are subjected to a prolonged exposure to a steady shear. This phenomenon,\nwhich is characterized by a yielding point, is found to be strongly dependent\non the packing fraction. However, it is not yet known how the effective\ninter-particle potential affects this transition. To this aim, we present a\nnumerical investigation of the rheology of equilibrium gels in which a\nshort-range depletion is complemented by a long-range electrostatic\ninteraction. We observe a single yielding event in the stress-strain curve,\noccurring at a fixed strain. The stress overshoot is found to follow a\npower-law dependence on the P\\'eclet number, with an exponent larger than that\nfound in depletion gels, suggesting that its value may depend systematically on\nthe underlying colloid-colloid interactions. We also establish a mapping\nbetween equilibrium states and steady states under shear, which allows us to\nidentify the structural modifications induced by the presence of the shear.\nRemarkably, we find that steady states corresponding to the same P\\'eclet\nnumber, obtained by different combinations of shear rate and solvent viscosity,\nshow identical structural and rheological properties. Our results highlight the\nimportance of understanding the coupling between colloidal interactions,\nsolvent effects, and flow to be able to describe the microscopic organization\nof colloidal particles under shear.",
        "positive": "Expansion of Liquid 4He Through the Lambda Transition: Zurek suggested [Nature 317 (1985) 505] that the Kibble mechanism, through\nwhich topological defects such as cosmic strings are believed to have been\ncreated in the early Universe, can also result in the formation of topological\ndefects in liquid 4He, i.e. quantised vortices, during rapid quenches through\nthe superfluid transition. Preliminary experiments [Hendry et al, Nature 368\n(1994) 315] seemed to support this idea in that the quenches produced the\npredicted high vortex-densities. The present paper describes a new experiment\nincorporating a redesigned expansion cell that minimises vortex creation\narising from conventional hydrodynamic flow. The post-quench line-densities of\nvorticity produced by the new cell are no more than 10^10 m^{-2}, a value that\nis at least two orders-of-magnitude less than the theoretical prediction. We\nconclude that most of the vortices detected in the original experiment must\nhave been created through conventional flow processes."
    },
    {
        "anchor": "Aggregation of flexible polyelectrolytes: Phase diagram and dynamics: Similarly-charged polymers in solution, known as polyelectrolytes, are known\nto form aggregated structures in the presence of oppositely charged\ncounterions. Understanding the dependence of the equilibrium phases and the\ndynamics of the process of aggregation on parameters such as backbone\nflexibility and charge density of such polymers is crucial for insights into\nvarious biological processes which involve biological polyelectrolytes such as\nprotein, DNA etc., Here, we use large-scale coarse-grained molecular dynamics\nsimulations to obtain the phase diagram of the aggregated structures of\nflexible charged polymers and characterize the morphology of the aggregates as\nwell as the aggregation dynamics, in the presence of trivalent counterions.\nThree different phases are observed depending on the charge density: no\naggregation, a finite bundle phase where multiple small aggregates coexist with\na large aggregate, and a fully phase separated phase. We show that the\nflexibility of the polymer backbone causes strong entanglement between charged\npolymers leading to additional time scales in the aggregation process. Such\nslowing down of the aggregation dynamics results in the exponent,\ncharacterizing the power law decay of the number of aggregates with time, to be\ndependent on the charge density of the polymers. These results are contrary to\nthose obtained for rigid polyelectrolytes, emphasizing the role of backbone\nflexibility.",
        "positive": "The random packing density of nearly spherical particles: Obtaining general relations between macroscopic properties of random\nassemblies, such as density, and the microscopic properties of their\nconstituent particles, such as shape, is a foundational challenge in the study\nof amorphous materials. By leveraging existing understanding of the random\npacking of spherical particles, we estimate the random packing density for all\nsufficiently spherical shapes. Our method uses the ensemble of random packing\nconfigurations of spheres as a reference point for a perturbative calculation,\nwhich we carry to linear order in the deformation. A fully analytic calculation\nshows that all sufficiently spherical shapes pack more densely than spheres.\nAdditionally, we use simulation data for spheres to calculate numerical\nestimates for nonspherical particles and compare these estimates to\nsimulations."
    },
    {
        "anchor": "Vibrational Effects on the Coefficient of Restitution: A ball dropped from a given height onto a surface, will bounce repeatedly\nbefore coming to rest. A ball bouncing on a thick plate will behave very\ndifferently than a ball bouncing off the thin lid of a container. For a plate\nwith a fixed thickness, a ball bouncing at the edge of a plate will be very\ndifferent from the ball bouncing off the middle of the plate. We study the\ncoefficient of restitution $\\epsilon$ for a steel ball bouncing steel plates of\nvarious thicknesses. We observe how $\\epsilon$ changes as the ball repeated\nbounces and finally comes to rest. Generally, $\\epsilon < 1$ due to the\ndissipation of kinetic energy of the ball into the plate. However this\ndissipated energy can come back into ball in its later bounces. We see the\nemergence of super-elastic collisions ($\\epsilon > 1$), implying that the ball\ngained Kinetic Energy due to the collision with the plate. We can increase the\nprobability of such super-elastic collisions (P$_{SE}$) by adding a spring to\nthe ball. We construct a simple theoretical model where the energy lost from\nprevious collisions are transferred back into later ones. This model is able to\nsimulate the occurrence of such super-elastic collisions.",
        "positive": "Theory of pore-driven and end-pulled polymer translocation dynamics\n  through a nanopore: An overview: We review recent progress on the theory of dynamics of polymer translocation\nthrough a nanopore based on the iso-flux tension propagation (IFTP) theory. We\ninvestigate both pore-driven translocation of flexible and a semi-flexible\npolymers, and the end-pulled case of flexible chains by means of the IFTP\ntheory and extensive molecular dynamics (MD) simulations. The validity of the\nIFTP theory can be quantified by the waiting time distributions of the monomers\nwhich reveal the details of the dynamics of the translocation process. The IFTP\ntheory allows a parameter-free description of the translocation process and can\nbe used to derive exact analytic scaling forms in the appropriate limits,\nincluding the influence due to the pore friction that appears as a finite-size\ncorrection to asymptotic scaling. We show that in the case of pore-driven\nsemi-flexible and end-pulled polymer chains the IFTP theory must be augmented\nwith an explicit {\\it trans} side friction term for a quantitative description\nof the translocation process."
    },
    {
        "anchor": "Comment on \"Twisted Protein Aggregates and Disease: The Stability of\n  Sickle Hemoglobin Fibers\": Aggregates of twisted protein fibers, such as sickle hemoglobin and actin,\nare important examples of biopolymers in which elastic interactions play a\ncrucial role in determining the (metastable) bundle radii. Here, we present a\ncorrected version of analysis on the stability of sickle hemoglobin fibers\nusing the classic nucleation theory.",
        "positive": "Dynamically induced effective interaction in periodically driven\n  granular mixtures: We discuss the microscopic origin of dynamical instabilities and segregation\npatterns discovered in granular mixtures under oscillating horizontal shear, by\ninvestigating, via molecular dynamics simulations, the effective interaction\nbetween like-particles. This turns out to be attractive at short distances and\nstrongly anisotropic, with a longer range repulsive shoulder along the\ndirection of oscillation. This features explain the system rich phenomenology,\nincluding segregation and stripe pattern formation. Finally, we show that a\nmodified Cahn-Hilliard equation, taking into account the characteristics of the\neffective interaction, is capable of describing the dynamics of the mixture."
    },
    {
        "anchor": "Motility-induced phase separation and coarsening in active matter: Active systems, or active matter, are self-driven systems which live, or\nfunction, far from equilibrium - a paradigmatic example which we focus on here\nis provided by a suspension of self-motile particles. Active systems are far\nfrom equilibrium because their microscopic constituents constantly consume\nenergy from the environment in order to do work, for instance to propel\nthemselves. The nonequilibrium nature of active matter leads to a variety of\nnon-trivial intriguing phenomena. An important one which has recently been the\nsubject of intense interest among biological and soft matter physicists is that\nof the so-called \"motility-induced phase separation\", whereby self-propelled\nparticles accumulate into clusters in the absence of any explicit attractive\ninteractions between them. Here we review the physics of motility-induced phase\nseparation, and discuss this phenomenon within the framework of the classic\nphysics of phase separation and coarsening. We also discuss theories for\nbacterial colonies where coarsening may be arrested. Most of this work will\nfocus on the case of run-and-tumble and active Brownian particles in the\nabsence of solvent-mediated hydrodynamic interactions - we will briefly discuss\nat the end their role, which is not currently fully understood in this context.",
        "positive": "Friction vs Texture at the Approach of a Granular Avalanche: We perform a novel analysis of the granular texture of a granular bed close\nto stability limit. Our analysis is based on a unique criterion of friction\nmobilisation in a simulated two-dimensional packing. In this way, we recover\nthe bimodal character of granular texture, and the coexistence of weak and\nstrong phases in the sense of distinct contacts populations. Moreover, we show\nthe existence of a well-defined subset of contacts within the weak contact\nnetwork. These contacts are characterized by their important friction, and form\na highly coherent population in terms of fabric. They play an antagonistic role\nwith respect to force chains. We are thus able to discriminate between\nincoherent contacts and coherent contacts in the weak phase, and to specify the\nrole that the latter plays in the destabilisation process."
    },
    {
        "anchor": "A model of surface roughness effect on triboelectric charging of\n  particles: Tribocharging increases due to deformation and penetration of surface\nasperities, enlarging the real contact area. These experimental results\ntranslate into a theoretical description of particle charging that resolves the\nsurface topology. Based on these findings, we propose a model that predicts the\ndependence of the particles' saturation charge on the impact velocity and\nsurface roughness.",
        "positive": "Two new topologically ordered glass phases of smectics confined in\n  anisotropic random media: We show that smectic liquid crystals confined in_anisotropic_ porous\nstructures such as e.g.,_strained_ aerogel or aerosil exhibit two new glassy\nphases. The strain both ensures the stability of these phases and determines\ntheir nature. One type of strain induces an ``XY Bragg glass'', while the other\ncreates a novel, triaxially anisotropic ``m=1 Bragg glass''. The latter\nexhibits anomalous elasticity, characterized by exponents that we calculate to\nhigh precision. We predict the phase diagram for the system, and numerous other\nexperimental observables."
    },
    {
        "anchor": "Using self-driven microswimmers for particle separation: Microscopic self-propelled swimmers capable of autonomous navigation through\ncomplex environments provide appealing opportunities for localization, pick-up\nand delivery of micro-and nanoscopic objects. Inspired by motile cells and\nbacteria, man-made microswimmers have been fabricated, and their motion in\npatterned surroundings has been experimentally studied. We propose to use\nself-driven artificial microswimmers for separation of binary mixtures of\ncolloids. We revealed different regimes of separation including one with a\nvelocity inversion. Our finding could be of use for various biological and\nmedical applications.",
        "positive": "Phonon transport properties of particulate physical gels: Particulate physical gels are sparse, low-density amorphous materials in\nwhich clusters of glasses are connected to form a heterogeneous network\nstructure. This structure is characterized by two length scales, $\\xi_s$ and\n$\\xi_G$: $\\xi_s$ measures the length of heterogeneities in the network\nstructure, and $\\xi_G$ is the size of glassy clusters. Accordingly, the\nvibrational states of such a material also exhibit a multiscale nature with two\ncharacteristic frequencies, $\\omega_\\ast$ and $\\omega_G$, which are associated\nwith $\\xi_s$ and $\\xi_G$, respectively: (i) phonon-like vibrations in the\nhomogeneous medium at $\\omega < \\omega_\\ast$, (ii) phonon-like vibrations in\nthe heterogeneous medium at $\\omega_\\ast < \\omega < \\omega_G$, and (iii)\ndisordered vibrations in the glassy clusters at $\\omega > \\omega_G$. Here, we\ndemonstrate that the multiscale characteristics seen in the static structures\nand vibrational states also extend to the phonon transport properties. Phonon\ntransport exhibits two distinct crossovers at the frequencies $\\omega_\\ast$ and\n$\\omega_G$~(or at wavenumbers of $\\sim \\xi_s^{-1}$ and $\\sim \\xi_G^{-1}$). In\nparticular, both transverse and longitudinal phonons cross over between\nRayleigh scattering at $\\omega < \\omega_\\ast$ and diffusive damping at\n$\\omega>\\omega_\\ast$. Remarkably, the Ioffe--Regel limit is located at the very\nlow frequency of $\\omega_\\ast$. Thus, phonon transport is localized above\n$\\omega_\\ast$, even where phonon-like vibrational states persist. This markedly\nstrong scattering behavior is caused by the sparse, porous structure of the\ngel."
    },
    {
        "anchor": "Heterogeneous aggregation in binary colloidal alloys: Molecular dynamics (MD) simulation has been employed to study the\nnonequilibrium structure formation of two types of particles in a colloidal\nsuspension, driven by type-dependent forces. We examined the time evolution of\nstructure formation as well as the structural properties of the resulting\naggregation by studying the radial distribution function (RDF). The resulting\naggregation is well described by a binary colloidal gelation. We compared the\nstructural properties to those for one type of particles. From the MD results,\nit is evident that there are significant differences between the RDF's of the\ntwo cases. Moreover, we found that the average coordination number is generally\nlarger in the monodisperse case for all area fractions considered. Thus, by\nmeans of heterogeneous aggregation, it is possible to obtain a wide variety of\nstructures while more close-packed structures are formed for monodisperse\ncolloidal aggregation.",
        "positive": "Fabrication of polyhedral particles from spherical colloids and their\n  self-assembly into rotator phases: Particle shape is a critical parameter that plays an important role in\nself-assembly, for example, in designing targeted complex structures with\ndesired properties. In the last decades an unprecedented range of monodisperse\nnanoparticle systems with control over the shape of the particles have become\navailable. In contrast, the choice of micron-sized colloidal building blocks of\nparticles with flat facets, i.e., particles with polygonal shapes, is\nsignificantly more limited. This can be attributed to the fact that, contrary\nto nanoparticles, the larger colloids are significantly harder to synthesize as\nsingle crystals. Herein, we demonstrate that the simplest building block, such\nas the micron-sized polymeric spherical colloidal particle, is already enough\nto fabricate particles with regularly placed flat facets, including completely\npolygonal shapes with sharp edges. As an illustration that the yields are high\nenough for further self-assembly studies we demonstrate the formation of 3D\nrotator phases of fluorescently labelled, micron-sized and charged rhombic\ndodecahedron particles. Our method for fabricating polyhedral particles opens a\nnew avenue for designing new materials."
    },
    {
        "anchor": "Effective Electrostatic Interactions in Colloid-Nanoparticle Mixtures: Interparticle interactions and bulk properties of colloidal suspensions can\nbe substantially modified by addition of nanoparticles. Extreme asymmetries in\nsize and charge between colloidal particles and nanoparticles present severe\ncomputational challenges to molecular-scale modeling of such complex systems.\nWe present a statistical mechanical theory of effective electrostatic\ninteractions that can greatly ease large-scale modeling of charged\ncolloid-nanoparticle mixtures. By applying a sequential coarse-graining\nprocedure, we show that a multicomponent mixture of charged colloids,\nnanoparticles, counterions, and coions can be mapped first onto a binary\nmixture of colloids and nanoparticles and then onto a one-component model of\ncolloids alone. In a linear-response approximation, the one-component model is\ngoverned by a single effective pair potential and a one-body volume energy,\nwhose parameters depend nontrivially on nano particle size, charge, and\nconcentration. To test the theory, we perform molecular dynamics simulations of\nthe two-component and one-component models and compute structural properties.\nFor moderate electrostatic couplings, colloid-colloid radial distribution\nfunctions and static structure factors agree closely between the two models,\nvalidating the sequential coarse-graining approach. Nanoparticles of sufficient\ncharge and concentration enhance screening of electrostatic interactions,\nweakening correlations between charged colloids and destabilizing suspensions,\nconsistent with experiments.",
        "positive": "Coefficient of Restitution for Viscoelastic Materials: An analytical expression of the coefficient of restitution for viscoelastic\nmaterials is derived for the viscous-dominant case, such as collisions of\npolymeric melt. The recently proposed normal impact force model between two\ncolliding viscoelastic droplets is employed. To analytically solve the\nnonlinear differential equation of deformation caused by the other droplet, a\nperturbation method is applied. By combining the forward collision and the\ninverse collision, we can get an analytical expression for the coefficient of\nrestitution, which can also be used to further analyze other properties related\nwith the viscoelasticity."
    },
    {
        "anchor": "Critical mingling and universal correlations in model binary active\n  liquids: Ensembles of driven or motile bodies moving along opposite directions are\ngenerically reported to self-organize into strongly anisotropic lanes. Here,\nbuilding on a minimal model of self-propelled bodies targeting opposite\ndirections, we first evidence a critical phase transition between a mingled\nstate and a phase-separated lane state specific to active particles. We then\ndemonstrate that the mingled state displays algebraic structural correlations\nalso found in driven binary mixtures. Finally, constructing a hydrodynamic\ntheory, we single out the physical mechanisms responsible for these universal\nlong-range correlations typical of ensembles of oppositely moving bodies.",
        "positive": "Structural disorder on small scales softens hierarchical structures: Hierarchically structured materials, which possess distinct features on\ndifferent length scales, are ubiquitous in nature and engineering. In many\ncases, one structural level may be ordered while another structural level may\nbe disordered. Here, we investigate the impact of structural disorder on the\nmechanical properties of hierarchical filamentous structures. Through\nsimulations of networks with two hierarchical levels, we show that disorder\ndoes not change how stiffness scales with the mean coordination number - the\naverage number of bonds per node - on large and small length scales. However,\nwe find that network rigidity and stiffness depend strongly on the presence or\nabsence of disorder on the small length scale, but not on the large length\nscale. In fact, the amount of material necessary for a fully connected, network\nordered on the small scale is insufficient to create even a marginally rigid\nnetwork with small-scale disorder. We trace these phenomena back to a\ndifference in the maximum mean coordination number on the small scale. While\nsingle length scale ordered and disordered networks have similar mean\ncoordination numbers in the interior and on surfaces, we find that disorder\nstrongly impacts the structure of surfaces, resulting in a larger fraction of\nsurface nodes on the small scale. While this effect increases in strength as\nlarge scale bonds become narrower, it persists even for bonds that are wider\nthan they are long (i.e., aspect ratios < 1)."
    },
    {
        "anchor": "Water-mediated interactions between hydrophobic and ionic species in\n  cylindrical nanopores: We use Metropolis Monte Carlo and umbrella sampling to calculate the free\nenergies of interaction of two methane molecules and their charged derivatives\nin cylindrical water-filled pores. Confinement strongly alters the interactions\nbetween the nonpolar solutes, and completely eliminates the solvent separated\nminimum (SSM) that is seen in bulk water. The free energy profiles show that\nthe methane molecules are either in contact or at separations corresponding to\nthe diameter and the length of the cylindrical pore. Analytic calculations that\nestimate the entropy of the solutes, which are solvated at the pore surface,\nqualitatively explain the shape of the free energy profiles. Adding charges of\nopposite sign and magnitude $0.4e$ or $e$ (where $e$ is the electronic charge)\nto the methane molecules decreases their tendency for surface solvation and\nrestores the SSM. We show that confinement induced ion-pair formation occurs\nwhenever $l_B/D \\sim O(1)$, where $l_B$ is the Bjerrum length, and $D$ is the\npore diameter. The extent of stabilization of the SSM increases with ion charge\ndensity as long as $l_B/D < 1$. In pores with $D \\le 1.2$ nm, in which the\nwater is strongly layered, increasing the charge magnitude from $0.4e$ to $e$\nreduces the stability of the SSM. As a result, ion-pair formation which occurs\nwith negligible probability in the bulk, is promoted. In larger diameter pores\nthat can accomodate a complete hydration layer around the solutes, the\nstability of the SSM is enhanced.",
        "positive": "Dielectric response with short-ranged electrostatics: The dielectric nature of polar liquids underpins much of their ability to act\nas useful solvents, but its description is complicated by the long-ranged\nnature of dipolar interactions. This is particularly pronounced under the\nperiodic boundary conditions commonly used in molecular simulations. In this\narticle, the dielectric properties of a water model whose intermolecular\nelectrostatic interactions are entirely short-ranged are investigated. This is\ndone within the framework of local molecular field theory (LMFT), which\nprovides a well controlled mean-field treatment of long-ranged electrostatics.\nThis short-ranged model gives a remarkably good performance on a number of\ncounts, and its apparent shortcomings are readily accounted for. These results\nnot only lend support to LMFT as an approach for understanding solvation\nbehavior, but are relevant to those developing interaction potentials based on\nlocal descriptions of liquid structure."
    },
    {
        "anchor": "Differential Dynamic Microscopy to characterize Brownian motion and\n  bacteria motility: We have developed a lab work module where we teach undergraduate students how\nto quantify the dynamics of a suspension of microscopic particles, measuring\nand analyzing the motion of those particles at the individual level or as a\ngroup. Differential Dynamic Microscopy (DDM) is a relatively recent technique\nthat precisely does that and constitutes an alternative method to more\nclassical techniques such as dynamics light scattering (DLS) or video particle\ntracking (VPT). DDM consists in imaging a particle dispersion with a standard\nlight microscope and a camera. The image analysis requires the students to code\nand relies on digital Fourier transform to obtain the intermediate scattering\nfunction, an autocorrelation function that characterizes the dynamics of the\ndispersion. We first illustrate DDM on the textbook case of colloids where we\nmeasure the diffusion coefficient. Then we show that DDM is a pertinent tool to\ncharacterize biologic systems such as motile bacteria i.e.bacteria that can\nself propel, where we not only determine the diffusion coefficient but also the\nvelocity and the fraction of motile bacteria. Finally, so that our paper can be\nused as a tutorial to the DDM technique, we have joined to this article movies\nof the colloidal and bacterial suspensions and the DDM algorithm in both Matlab\nand Python to analyze the movies.",
        "positive": "Forces and torques on rigid inclusions in an elastic environment:\n  resulting matrix-mediated interactions, displacements, and rotations: Embedding rigid inclusions into elastic matrix materials is a procedure of\nhigh practical relevance, for instance for the fabrication of elastic composite\nmaterials. We theoretically analyze the following situation. Rigid spherical\ninclusions are enclosed by a homogeneous elastic medium under stick boundary\nconditions. Forces and torques are directly imposed from outside onto the\ninclusions, or are externally induced between them. The inclusions respond to\nthese forces and torques by translations and rotations against the surrounding\nelastic matrix. This leads to elastic matrix deformations, and in turn results\nin mutual long-ranged matrix-mediated interactions between the inclusions.\nAdapting a well-known approach from low-Reynolds-number hydrodynamics, we\nexplicitly calculate the displacements and rotations of the inclusions from the\nexternally imposed or induced forces and torques. Analytical expressions are\npresented as a function of the inclusion configuration in terms of\ndisplaceability and rotateability matrices. The role of the elastic environment\nis implicitly included in these relations. That is, the resulting expressions\nallow a calculation of the induced displacements and rotations directly from\nthe inclusion configuration, without having to explicitly determine the\ndeformations of the elastic environment. In contrast to the hydrodynamic case,\ncompressibility of the surrounding medium is readily taken into account. We\npresent the complete derivation based on the underlying equations of linear\nelasticity theory. In the future, the method will, for example, be helpful to\ncharacterize the behavior of externally tunable elastic composite materials, to\naccelerate numerical approaches, as well as to improve the quantitative\ninterpretation of microrheological results."
    },
    {
        "anchor": "Hydrodynamically Induced Aggregation in Two-Dimensional Active Systems: We investigate a system of co-oriented active particles interacting only via\nhydrodynamic and steric interactions. We offer a new method of calculating the\nflow created by any active particle in a 2D fluid, focusing on the dynamics of\nflow fields with a high-order spatial decay, which we analyze using a geometric\nHamiltonian. We show that when orientational degrees of freedom are quenched,\nand the flow has a single, odd power decay, such many-particle systems lead to\nstable, fractal-like aggregation, with the only exceptions being the force\ndipole. We discuss how our results can easily be generalized to more\ncomplicated force distributions and to other effective two-dimensional systems.",
        "positive": "Tuning local microstructure of colloidal gels by ultrasound-activated\n  deformable inclusions: Colloidal gels possess a memory of previous shear events, both steady and\noscillatory. This memory, embedded in the microstructure, affects the\nmechanical response of the gel, and therefore enables precise tuning of the\nmaterial properties under careful preparation. Here we demonstrate how the\ndynamics of a deformable inclusion, namely a bubble, can be used to locally\ntune the microstructure of a colloidal gel. We examine two different phenomena\nof bubble dynamics that apply a local strain to the surrounding material:\ndissolution due to mass transfer, with a characteristic strain rate of\n$10^{-3}$ s$^{-1}$; and volumetric oscillations driven by ultrasound, with a\ncharacteristic frequency of $10^4$ s$^{-1}$.\n  We characterise experimentally the microstructure of a model colloidal gel\naround bubbles in a Hele-Shaw geometry using confocal microscopy and particle\ntracking. In bubble dissolution experiments, we observe the formation of a\npocket of solvent next to the bubble surface, but marginal changes to the\nmicrostructure. In experiments with ultrasound-induced bubble oscillations, we\nobserve a striking rearrangement of the gel particles into a microstructure\nwith increased local ordering. High-speed bright-field microscopy reveals the\noccurrence of both high-frequency bubble oscillations and steady microstreaming\nflow; both are expected to contribute to the emergence of the local order in\nthe microstructure. These observations open the way to local tuning of\ncolloidal gels based on deformable inclusions controlled by external pressure\nfields."
    },
    {
        "anchor": "Role of interfacial elasticity for the rheological properties of\n  saponin-stabilized emulsions: Hypothesis Saponins are natural surfactants which can provide highly\nviscoelastic interfaces. This property can be used to quantify precisely the\neffect of interfacial dilatational elasticity on the various rheological\nproperties of bulk emulsions. Experiments We measured the interfacial\ndilatational elasticity of adsorption layers from four saponins (Quillaja,\nEscin, Berry, Tea) adsorbed on hexadecane-water and sunflower oil-water\ninterfaces. In parallel, the rheological properties under steady and\noscillatory shear deformations were measured for bulk emulsions, stabilized by\nthe same saponins (oil volume fraction between 75 and 85 %). Findings Quillaja\nsaponin and Berry saponin formed solid adsorption layers (shells) on the\nSFO-water interface. As a consequence, the respective emulsions contained\nnon-spherical drops. For the other systems, the interfacial elasticities varied\nbetween 2 mN/m and 500 mN/m. We found that this interfacial elasticity has very\nsignificant impact on the emulsion shear elasticity, moderate effect on the\ndynamic yield stress, and no effect on the viscous stress of the respective\nsteadily sheared emulsions. The last conclusion is not trivial, because the\ndilatational surface elasticity is known to have strong impact on the viscous\nstress of steadily sheared foams. Mechanistic explanations of all observed\neffects are described.",
        "positive": "Learning-based approach to plasticity in athermal sheared amorphous\n  packings: Improving softness: The plasticity of amorphous solids undergoing shear is characterized by\nquasi-localized rearrangements of particles. While many models of plasticity\nexist, the precise relationship between plastic dynamics and the structure of a\nparticle's local environment remains an open question. Previously, machine\nlearning was used to identify a structural predictor of rearrangements, called\n\"softness.\" Although softness has been shown to predict which particles will\nrearrange with high accuracy, the method can be difficult to implement in\nexperiments where data is limited and the combinations of descriptors it\nidentifies are often difficult to interpret physically. Here we address both of\nthese weaknesses, presenting two major improvements to the standard softness\nmethod. First, we present a natural representation of each particle's observed\nmobility, allowing for the use of statistical models which are both simpler and\nprovide greater accuracy in limited data sets. Second, we employ persistent\nhomology as a systematic means of identifying simple, topologically-informed,\nstructural quantities that are easy to interpret and measure experimentally. We\ntest our methods on two-dimensional athermal packings of soft spheres under\nquasi-static shear. We find that the same structural information which predicts\nsmall variations in the response is also predictive of where plastic events\nwill localize. We also find that excellent accuracy is achieved in athermal\nsheared packings using simply a particle's species and the number of nearest\nneighbor contacts."
    },
    {
        "anchor": "Network Analysis of Particles and Grains: The arrangements of particles and forces in granular materials have a complex\norganization on multiple spatial scales that ranges from local structures to\nmesoscale and system-wide ones. This multiscale organization can affect how a\nmaterial responds or reconfigures when exposed to external perturbations or\nloading. The theoretical study of particle-level, force-chain, domain, and bulk\nproperties requires the development and application of appropriate physical,\nmathematical, statistical, and computational frameworks. Traditionally,\ngranular materials have been investigated using particulate or continuum\nmodels, each of which tends to be implicitly agnostic to multiscale\norganization. Recently, tools from network science have emerged as powerful\napproaches for probing and characterizing heterogeneous architectures across\ndifferent scales in complex systems, and a diverse set of methods have yielded\nfascinating insights into granular materials. In this paper, we review work on\nnetwork-based approaches to studying granular matter and explore the potential\nof such frameworks to provide a useful description of these systems and to\nenhance understanding of their underlying physics. We also outline a few open\nquestions and highlight particularly promising future directions in the\nanalysis and design of granular matter and other kinds of material networks.",
        "positive": "Correlation functions of main-chain polymer nematics constrained by\n  tensorial and vectorial conservation laws: We present and analyze correlation functions of a main-chain polymer nematic\nin a continuum worm-like chain description for two types of constraints\nformalized by the tensorial and vectorial conservation laws, both originating\nin the microscopic chain integrity, i.e., the conectivity of the polymer\nchains. In particular, our aim is to identify the features of the correlation\nfunctions that are most susceptible to the differences between the two\nconstraints. Besides the density and director autocorrelations in both the\ntensorial and vectorial cases, we calculate also the density -- director\ncorrelation functions, the latter being a direct signature of the presence of a\nspecific constraint. Its amplitude is connected to the strength of the\nconstraint and is zero if none of the constraints is present, i.e., for a\nstandard non-polymeric nematic. Generally, the correlation functions with the\nconstraints differ substantially from the correlation functions in the\nnon-polymeric case, if the constraints are strong which in practice requires\nlong chains. Moreover, for the tensorial conservation law to be well\ndistinguishable from the vectorial one, the chain persistence length should be\nmuch smaller than the total length of the chain, so that hairpins (chain\nbackfolding) are numerous and the polar order is small."
    },
    {
        "anchor": "Elasto-capillary interaction of particles on the surfaces of ultra-soft\n  gels: a novel route to study self-assembly and soft lubrication: We study the interaction of small hydrophobic particles on the surface of an\nultra-soft elastic gel, in which a small amount of elasticity of the medium\nbalances the weights of the particles. The excess energy of the surface of the\ndeformed gel causes them to attract as is the case with the generic capillary\ninteractions of particles on a liquid surface. The variation of the\ngravitational potential energies of the particles resulting from their descents\nin the gel coupled with the superposition principle of Nicolson allow a fair\nestimation of the distance dependent attractive energy of the particles. This\nenergy follows a modified Bessel function of the second kind with a\ncharacteristic elastocapillary decay length that decreases with the elasticity\nof the medium. An interesting finding of this study is that the particles on\nthe gel move towards each other as if the system possesses a negative\ndiffusivity that is inversely proportional to friction. This study illustrates\nhow the capillary interaction of particles is modified by the elasticity of the\nmedium, which is expected to have important implications in the surface force\ndriven self-assembly of particles. In particular, this study points out that\nthe range and the strength of the capillary interaction can be tuned in by\nappropriate choices of the elasticity of the support and the interfacial\ntension of the surrounding medium. Manipulation of the particle interactions is\nexemplified in such fascinating mimicry of the biological processes as the\ntubulation, phagocytic engulfment and in the assembly of particles that can be\nused to study nucleation and clustering phenomena in well controlled settings.",
        "positive": "Crack initiation in viscoelastic materials: In viscoelastic materials, individually short-lived bonds collectively result\nin a mechanical resistance which is long-lived but finite, as ultimately cracks\nappear. Here we provide a microscopic mechanism by which cracks emerge from the\nnonlinear local bond dynamics. This mechanism is different from crack\ninitiation in solids, which is governed by a competition between elastic and\nadhesion energy. We provide and numerically verify analytical equations for the\ndependence of the critical crack length on the bond kinetics and applied\nstress."
    },
    {
        "anchor": "A Numerical Investigation of Analyte Size Effects in Nanopore Sensing\n  Systems: We investigate the ionic current modulation in DNA nanopore translocation\nsetups by numerically solving the electrokinetic mean-field equations for an\nidealized model. Specifically, we study the dependence of the ionic current on\nthe relative length of the translocating molecule. Our simulations show a\nsignificantly smaller ionic current for DNA molecules that are shorter than the\npore at low salt concentrations. These effects can be ascribed to the\npolarization of the ion cloud along the DNA that leads to an opposing electric\ndipole field. Our results for DNA shine light on the observed discrepancy\nbetween infinite pore models and experimental data on various sized DNA\ncomplexes.",
        "positive": "Facile equilibration of well-entangled semiflexible bead-spring polymer\n  melts: The widely used double-bridging hybrid (DBH) method for equilibrating\nsimulated entangled polymer melts [R. Auhl et al., J. Chem. Phys. v. 119, p.\n12718, 2003] loses its effectiveness as chain stiffness increases into the\nsemiflexible regime because the energy barriers associated with double-bridging\nMonte Carlo moves become prohibitively high. Here we overcome this issue by\ncombining DBH with the use of core-softened pair potentials. This reduces the\nenergy barriers substantially, allowing us to equilibrate melts with $N \\simeq\n40 N_e$ and chain stiffnesses all the way up to the isotropic-nematic\ntransition using simulations of no more than 100 million timesteps. For\nsemiflexible chains, our method is several times faster than standard DBH; we\nexploit this speedup to develop improved expressions for Kremer-Grest melts'\nchain-stiffness-dependent Kuhn length $\\ell_K$ and entanglement length $N_e$."
    },
    {
        "anchor": "Topological Transition to a Critical Phase in a Two-dimensional 3-Vector\n  Model with non-Abelian Fundamental Group: A Simulational Study: Two-dimensional 3-vector (\\textit{d}=2, \\textit{n}=3) lattice model with\ninversion site symmetry and fundamental group of its order-parameter space\n$\\Pi_1 (\\mathcal{R})= Z_{2}$, did not exhibit the expected topological\ntransition despite stable defects associated with its uniaxial orientational\norder. This model is investigated specifically requiring the medium to host\ndistinct classes of defects associated with the three ordering directions,\nfacilitating their simultaneous interactions. The necessary non-Abelian\nisotropy subgroup of $\\mathcal{R}$ is realized by assigning $D_{2}$ site\nsymmetry, resulting in $\\Pi_1 (\\mathcal{R})= \\mathbb{Q }$ (the group of\nquaternions). With liquid crystals serving as prototype model, a general\nbiquadratic Hamiltonian is chosen to incorporate equally attractive\ninteractions among the three local directors resulting in an orientational\norder with the desired topology. A Monte Carlo investigation based on the\ndensity of states shows that this model exhibits a transition, simultaneously\nmediated by the three distinct defects with topological charge $1/2$\n(disclinations), to a low-temperature critical state characterized by a line of\ncritical points with quasi-long range order of its directors, their power-law\nexponents vanishing as temperature tends to zero. It is argued that with\n\\textit{n}=3, simultaneous participation of all spin degrees through their\nhomotopically inequivalent defects is necessary to mediate a transition in the\ntwo-dimensional system to a topologically ordered state.",
        "positive": "Wetting-induced budding of vesicles in contact with several aqueous\n  phases: Osmotic deflation of vesicles enclosing two liquid phases can lead to bulging\nof one of the phases from the vesicle body. This budding process is preceded by\na complete to partial wetting transition of one of the liquid phases on the\nmembrane and depends on the membrane tensions and the tension of the interface\nbetween the enclosed liquid phases. These tensions dominate in different\nmorphology regimes, the crossover of which initiates the budding process. In\naddition, the degree of budding can be controlled by aspiration via\nmicropipettes. We also demonstrate that the budding direction can be reversed\nif there are two external phases in contact with the vesicle."
    },
    {
        "anchor": "Generalized Berreman's model of the elastic surface free energy of a\n  nematic liquid crystal on a sawtoothed substrate: In this paper we present a generalization of Berreman's model for the elastic\ncontribution to the surface free-energy density of a nematic liquid crystal in\npresence of a sawtooth substrate which favours homeotropic anchoring, as a\nfunction of the wavenumber of the surface structure $q$, the tilt angle\n$\\alpha$ and the surface anchoring strength $w$. In addition to the previously\nreported non-analytic contribution proportional to $q\\ln q$, due to the\nnucleation of disclination lines at the wedge bottoms and apexes of the\nsubstrate, the next-to-leading contribution is proportional to $q$ for a given\nsubstrate roughness, in agreement with Berreman's predictions. We characterise\nthis term, finding that it has two contributions: the deviations of the nematic\ndirector field with respect to the corresponding to the isolated disclination\nlines, and their associated core free energies. Comparison with the results\nobtained from the Landau-de Gennes model shows that our model is quite accurate\nin the limit $wL>1$, when strong anchoring conditions are effectively achieved.",
        "positive": "Irreversibility and biased ensembles in active matter: Insights from\n  stochastic thermodynamics: Active systems evade the rules of equilibrium thermodynamics by constantly\ndissipating energy at the level of their microscopic components. This energy\nflux stems from the conversion of a fuel, present in the environment, into\nsustained individual motion. It can lead to collective effects without any\nequilibrium equivalent, such as a phase separation for purely repulsive\nparticles, or a collective motion (flocking) for aligning particles. Some of\nthese effects can be rationalized by using equilibrium tools to recapitulate\nnonequilibrium transitions. An important challenge is then to delineate\nsystematically to which extent the character of these active transitions is\ngenuinely distinct from equilibrium analogs. We review recent works that use\nstochastic thermodynamics tools to identify, for active systems, a measure of\nirreversibility comprising a coarse-grained or informatic entropy production.\nWe describe how this relates to the underlying energy dissipation or\nthermodynamic entropy production, and how it is influenced by collective\nbehavior. Then, we review the possibility to construct thermodynamic ensembles\nout-of-equilibrium, where trajectories are biased towards atypical values of\nnonequilibrium observables. We show that this is a generic route to discovering\nunexpected phase transitions in active matter systems, which can also inform\ntheir design."
    },
    {
        "anchor": "Dynamics of Fluid Vesicles in Oscillatory Shear Flow: The dynamics of fluid vesicles in oscillatory shear flow was studied using\ndifferential equations of two variables: the Taylor deformation parameter and\ninclination angle $\\theta$. In a steady shear flow with a low viscosity\n$\\eta_{\\rm {in}}$ of internal fluid, the vesicles exhibit steady tank-treading\nmotion with a constant inclination angle $\\theta_0$. In the oscillatory flow\nwith a low shear frequency, $\\theta$ oscillates between $\\pm \\theta_0$ or\naround $\\theta_0$ for zero or finite mean shear rate $\\dot\\gamma_{\\rm m}$,\nrespectively. As shear frequency $f_{\\gamma}$ increases, the vesicle\noscillation becomes delayed with respect to the shear oscillation, and the\noscillation amplitude decreases. At high $f_{\\gamma}$ with $\\dot\\gamma_{\\rm\nm}=0$, another limit-cycle oscillation between $\\theta_0-\\pi$ and $-\\theta_0$\nis found to appear. In the steady flow, $\\theta$ periodically rotates\n(tumbling) at high $\\eta_{\\rm {in}}$, and $\\theta$ and the vesicle shape\noscillate (swinging) at middle $\\eta_{\\rm {in}}$ and high shear rate. In the\noscillatory flow, the coexistence of two or more limit-cycle oscillations can\noccur for low $f_{\\gamma}$ in these phases. For the vesicle with a fixed shape,\nthe angle $\\theta$ rotates back to the original position after an oscillation\nperiod. However, it is found that a preferred angle can be induced by small\nthermal fluctuations.",
        "positive": "Derivation of the Derjaguin approximation for the case of inhomogeneous\n  solvents: The Derjaguin approximation (DA) relates the force between curved surfaces to\nthe interaction free energy between parallel planes. It is typically derived by\nconsidering the direct interaction between the bodies involved, thus treating\nthe effect of an intervening solvent implicitly by a rescaling of the\ncorresponding Hamaker constant. Here, we provide a generalization of DA to the\ncase of a molecular medium between the bodies, as is the case in most\napplications. The derivation is based on an explicit statistical-mechanical\ntreatment of the contribution to the interaction force from a molecular solvent\nusing a general expression for intermolecular and molecule-surface\ninteractions. Starting from an exact expression for the force, DA is arrived at\nby a series of well-defined approximations. Our results show that DA remains\nvalid in a molecular solvent as long as (i) the surface-molecule interactions\nare of much shorter range than the radius R of the sphere and (ii) the density\ncorrelation length in the solvent is smaller than R. We then extend our\nanalysis to the case where a phase transition occurs between the surfaces,\nwhich cannot easily be covered using a statistical-mechanical formalism due to\nthe discontinuous change in the density of the medium. Instead using a\ncontinuum thermodynamic description, we show that this phase transformation\ninduces an attractive force between the bodies, and that the force between\ncurved surfaces can be related to the free energy in the corresponding planar\ncase, in accordance with DA."
    },
    {
        "anchor": "Constant spacing in filament bundles: Assemblies of filaments appear in a wide range of systems: from biopolymer\nbundles, columnar liquid crystals, and superconductor vortex arrays; to\nfamiliar macroscopic materials, like ropes, cables and textiles. Interactions\nbetween the constituent filaments in such systems are most sensitive to the\n{\\it distance of closest approach} between the central curves which approximate\ntheir configuration, subjecting these distinct assemblies to common geometric\nconstraints. In this paper, we consider two distinct notions of constant\nspacing in multi-filament packings in $\\mathbb{R}^3$: {\\it equidistance}, where\nthe distance of closest approach is constant along the length of filament\npairs; and {\\it isometry}, where the distances of closest approach between all\nneighboring filaments are constant and equal. We show that, although any smooth\ncurve in $\\mathbb{R}^3$ permits one dimensional families of collinear\nequidistant curves belonging to a ruled surface, there are only two families of\ntangent fields with mutually equidistant integral curves in $\\mathbb{R}^3$. The\nrelative shapes and configurations of curves in these families are highly\nconstrained: they must be either (isometric) developable domains, which can\nbend, but not twist; or (non-isometric) constant-pitch helical bundles, which\ncan twist, but not bend. Thus, simultaneously bent and twisted filament\ntextures, such as twisted toroids of condensed DNA plasmids or wire ropes, are\ndoubly frustrated: twist frustrates constant neighbor spacing in the\ncross-section, while non-equidistance requires longitudinal variations of\ninter-filament spacing. To illustrate the consequences of the failure of\nequidistance, we compare spacing in three \"almost equidistant\" ansatzes for\ntwisted toroidal bundles and use our formulation of equidistance to construct\nupper bounds on the growth of longitudinal variations of spacing with bundle\nthickness.",
        "positive": "Entropy Crisis, Defects and the Role of Competition in Monatomic Glass\n  Formers: We establish the existence of an entropy crisis in monatomic glass formers.\nThe work finally shows that the entropy crisis is ubiqutous in all supercooled\nliquids. We also study the roles of defects and energetic competition on the\nideal glass."
    },
    {
        "anchor": "Probing local nonlinear viscoelastic properties in soft materials: Minimally invasive experimental methods that can measure local rate dependent\nmechanical properties are essential in understanding the behaviour of soft and\nbiological materials in a wide range of applications. Needle based measurement\ntechniques such as Cavitation Rheology and Volume Controlled Cavity Expansion\n(VCCE), allow for minimally invasive local mechanical testing, but have been\nlimited to measuring the elastic material properties. Here, we propose several\nenhancements to the VCCE technique to adapt it for characterization of\nviscoelastic response at low to medium stretch rates ($10^{-2}$ - $1$\ns${}^{-1}$). The proposed technique performs several cycles of\nexpansion-relaxation at controlled stretch rates in a cavity expansion setting\nand then employs a large deformation viscoelastic model to capture the measured\nmaterial response. Application of the technique to soft PDMS rubber reveals\nsignificant rate dependent material response with high precision and\nrepeatability, while isolating equilibrated states that are used to directly\ninfer the quasistatic elastic modulus. The technique is further established by\ndemonstrating its ability to capture changes in the rate dependent material\nresponse of a tuneable PDMS system. The measured viscoelastic properties are\nused to explain earlier reports of rate insensitive material response by needle\nbased methods: it is demonstrated that the conventional use of constant\nvolumetric rate cavity expansion can induce high stretch rates that lead to\nviscoelastic stiffening and an illusion of rate insensitive material response.\nWe thus conclude with a cautionary note on possible overestimation of the\nquasistatic elastic modulus in previous studies and suggest that the stretch\nrate controlled expansion protocol, proposed in this work, is essential for\naccurate estimation of both quasistatic and dynamic material parameters.",
        "positive": "Emergent comet-like swarming of optically driven thermally active\n  colloids: We propose a simple system of optically driven colloids that convert light\ninto heat and move in response to self- and collectively- generated thermal\ngradients. We show that the system exhibits self-organization into a moving\ncomet-like swarm and characterize the structure and response of the swarm to a\nlight intensity dependent external tuning parameter. We observe many\ninteresting features in this nonequilibrium system including circulation and\nevaporation, intensity-dependent shape, density and temperature fluctuations,\nand ejection of hot colloids from the swarm tip."
    },
    {
        "anchor": "Energy Transfer in a Molecular Motor in Kramers' Regime: We present a theoretical treatment of energy transfer in a molecular motor\ndescribed in terms of overdamped Brownian motion on a multidimensional tilted\nperiodic potential. The tilt acts as a thermodynamic force driving the system\nout of equilibrium and, for non-separable potentials, energy transfer occurs\nbetween degrees of freedom. For deep potential wells, the continuous theory\ntransforms to a discrete master equation that is tractable analytically. We use\nthis master equation to derive formal expressions for the hopping rates, drift,\ndiffusion, efficiency and rate of energy transfer in terms of the thermodynamic\nforce. These results span both strong and weak coupling between degrees of\nfreedom, describe the near and far from equilibrium regimes, and are consistent\nwith generalized detailed balance and the Onsager relations. We thereby derive\na number of diverse results for molecular motors within a single theoretical\nframework.",
        "positive": "Periodic necking of misfit hyperelastic filaments embedded in a soft\n  matrix: The necking instability is a precursor to tensile failure and rupture of\nmaterials. A quasistatically loaded free-standing uniaxial specimen typically\nexhibits necking at a single location, corresponding to a long wavelength\nbifurcation mode. If confined to a substrate or embedded in a matrix, the same\nfilament can exhibit periodic necking thus creating segments of finite length.\nWhile periodic instabilities have been extensively studied in ductile metal\nfilaments and thin sheets, less is known about necking in hyperelastic\nmaterials. There is a renewed interest in the role of necking in novel\nmaterials to advance fabrication processes and to explain fragmentation\nphenomena observed in 3D printed active biological matter. In both cases\nmaterials are not well described by existing frameworks that employ J2\nplasticity, and existing studies ignore the role of misfit stretches that may\nemerge in these systems through chemical or biological contraction. To address\nthese limitations, we first experimentally demonstrate the role of the matrix\non the necking and fragmentation of a compliant embedded filament. Using a\nstrain softening generalized hyperelastic model, our analytical bifurcation\nanalysis explains the experimental observations and agrees with numerical\npredictions. The analysis reveals 3 distinct bifurcation modes: a long\nwavelength necking, recovering the Considere criterion; a periodic necking\nobserved in our experiments; and a short wavelength mode characterized by\nlocalization along the center cord of the filament and independent of the\nfilm-to-matrix stiffness ratio. We find that the softening coefficient and the\nfilament misfit stretch can significantly influence the stability threshold and\nobserved wavelength, respectively. Our results can guide the design and\nfabrication of composite materials and explain the fragmentation processes\nobserved in active biological materials."
    },
    {
        "anchor": "Biaxial nematic phases in fluids of hard board-like particles: We use density-functional theory, of the fundamental-measure type, to study\nthe relative stability of the biaxial nematic phase, with respect to\nnon-uniform phases such as smectic and columnar, in fluids made of hard\nboard-like particles with sizes $\\sigma_1>\\sigma_2>\\sigma_3$. A\nrestricted-orientation (Zwanzig) approximation is adopted. Varying the ratio\n$\\kappa_1=\\sigma_1/\\sigma_2$ while keeping $\\kappa_2=\\sigma_2/\\sigma_3$, we\npredict phase diagrams for various values of $\\kappa_2$ which include all the\nuniform phases: isotropic, uniaxial rod- and plate-like nematics, and biaxial\nnematic. In addition, spinodal instabilities of the uniform phases with respect\nto fluctuations of the smectic, columnar and plastic-solid type, are obtained.\nIn agreement with recent experiments, we find that the biaxial nematic phase\nbegins to be stable for $\\kappa_2\\simeq 2.5$. Also, as predicted by previous\ntheories and simulations on biaxial hard particles, we obtain a region of\nbiaxility centred on $\\kappa_1\\approx\\kappa_2$ which widens as $\\kappa_2$\nincreases. For $\\kappa_2\\agt 5$ the region $\\kappa_2\\approx\\kappa_1$ of the\npacking-fraction vs. $\\kappa_1$ phase diagrams exhibits interesting topologies\nwhich change qualitatively with $\\kappa_2$. We have found that an increasing\nbiaxial shape anisotropy favours the formation of the biaxial nematic phase.\nOur study is the first to apply FMT theory to biaxial particles and, therefore,\nit goes beyond the second-order virial approximation. Our prediction that the\nphase diagram must be asymmetric is a genuine result of the present approach,\nwhich is not accounted for by previous studies based on second-order theories.",
        "positive": "Directed Motion of Liquid Crystal Skyrmions With Oscillating Fields: Using continuum simulations, we show that under a sinusoidal electric field,\nliquid crystal skyrmions undergo periodic shape oscillations which produce\ncontrolled directed motion. The speed of the skyrmion is non-monotonic in the\nfrequency of the applied field, and exhibits multiple reversals of the motion\nas a function of changing frequency. We map out the dynamical regime diagram of\nthe forward and reverse motion for two superimposed ac driving frequencies, and\nshow that the reversals and directed motion can occur even when only a single\nac driving frequency is present. Using pulsed ac driving, we demonstrate that\nthe motion arises due to an asymmetry in the relaxation times of the skyrmion\nshape. We discuss the connection between our results and ratchet effects\nobserved in systems without asymmetric substrates."
    },
    {
        "anchor": "The dune size distribution and scaling relations of barchan dune fields: Barchan dunes emerge as a collective phenomena involving the generation of\nthousands of them in so called barchan dune fields. By measuring the size and\nposition of dunes in Moroccan barchan dune fields, we find that these dunes\ntend to distribute uniformly in space and follow an unique size distribution\nfunction. We introduce an analyticalmean-field approach to show that this\nempirical size distribution emerges from the interplay of dune collisions and\nsand flux balance, the two simplest mechanisms for size selection. The\nanalytical model also predicts a scaling relation between the fundamental\nmacroscopic properties characterizing a dune field, namely the inter-dune\nspacing and the first and second moments of the dune size distribution.",
        "positive": "Compaction in Granular Solid Hydrodynamics: Compaction is considered and embedded into broader granular behavior.\nReversible compaction is related to the pressure exerted by agitated grains, a\nquantity relevant to dense flow. Irreversible compaction is derived from the\nloss of elastic deformation, the physics behind elasto-plastic flows."
    },
    {
        "anchor": "The prolate-to-oblate shape transition of phospholipid vesicles in\n  response to frequency variation of an AC electric field can be explained by\n  the dielectric anisotropy of a phospholipid bilayer: The external electric field deforms flaccid phospholipid vesicles into\nspheroidal bodies, with the rotational axis aligned with its direction.\nDeformation is frequency dependent: in the low frequency range (~ 1 kHz), the\ndeformation is typically prolate, while increasing the frequency to the 10 kHz\nrange changes the deformation to oblate. We attempt to explain this behaviour\nwith a theoretical model, based on the minimization of the total free energy of\nthe vesicle. The energy terms taken into account include the membrane bending\nenergy and the energy of the electric field. The latter is calculated from the\nelectric field via the Maxwell stress tensor, where the membrane is modelled as\nanisotropic lossy dielectric. Vesicle deformation in response to varying\nfrequency is calculated numerically. Using a series expansion, we also derive a\nsimplified expression for the deformation, which retains the frequency\ndependence of the exact expression and may provide a better substitute for the\nseries expansion used by Winterhalter and Helfrich, which was found to be valid\nonly in the limit of low frequencies. The model with the anisotropic membrane\npermittivity imposes two constraints on the values of material constants:\ntangential component of dielectric permittivity tensor of the phospholipid\nmembrane must exceed its radial component by approximately a factor of 3; and\nthe membrane conductivity has to be relatively high, approximately one tenth of\nthe conductivity of the external aqueous medium.",
        "positive": "Tests of mode coupling theory in a simple model for two-component\n  miscible polymer blends: We present molecular dynamics simulations on the structural relaxation of a\nsimple bead-spring model for polymer blends. The introduction of a different\nmonomer size induces a large time scale separation for the dynamics of the two\ncomponents. Simulation results for a large set of observables probing density\ncorrelations, Rouse modes, and orientations of bond and chain end-to-end\nvectors, are analyzed within the framework of the Mode Coupling Theory (MCT).\nAn unusually large value of the exponent parameter is obtained. This feature\nsuggests the possibility of an underlying higher-order MCT scenario for dynamic\narrest."
    },
    {
        "anchor": "Hydrophobicity Scaling of Aqueous Interfaces by an Electrostatic Mapping: An understanding of the hydrophobicity of complex heterogeneous molecular\nassemblies is crucial to characterize and predict interactions between\nbiomolecules. As such, uncovering the subtleties of assembly processes hinges\non an accurate classification of the relevant interfaces involved, and much\neffort has been spent on developing so-called \"hydrophobicity maps.\" In this\nwork, we introduce a novel electrostatics-based mapping of aqueous interfaces\nthat focuses on the collective, long-wavelength electrostatic response of water\nto the presence of nearby surfaces. In addition to distinguishing between\nhydrophobic and hydrophilic regions of heterogeneous surfaces, this\nelectrostatic mapping can also differentiate between hydrophilic regions that\npolarize nearby waters in opposing directions. We therefore expect this\napproach to find use in predicting the location of possible water-mediated\nhydrophilic interactions, in addition to the more commonly emphasized\nhydrophobic interactions that can also be of significant importance.",
        "positive": "Soft Spheres Make More Mesophases: We use both mean-field methods and numerical simulation to study the phase\ndiagram of classical particles interacting with a hard-core and repulsive, soft\nshoulder. Despite the purely repulsive interaction, this system displays a\nremarkable array of aggregate phases arising from the competition between the\nhard-core and shoulder length scales. In the limit of large shoulder width to\ncore size, we argue that this phase diagram has a number of universal features,\nand classify the set of repulsive shoulders that lead to aggregation at high\ndensity. Surprisingly, the phase sequence and aggregate size adjusts so as to\nkeep almost constant inter-aggregate separation."
    },
    {
        "anchor": "Active Segregation Dynamics in the Living Cell: In this paper, we bring together our efforts in identifying and understanding\nnonequilibrium phase segregation driven by active processes in the living cell,\nwith special focus on the segregation of cell membrane components driven by\nactive contractile stresses arising from cortical actomyosin. This also has\nimplications for active segregation dynamics in membraneless regions within the\ncytoplasm and nucleus (3d). We formulate an active version of the Flory-Huggins\ntheory that incorporates a contribution from fluctuating active stresses. Apart\nfrom knitting together some of our past theoretical work in a comprehensive\nnarrative, we highlight some new results, and establish a correspondence with\nrecent studies on Active Model B/B+. We point to the many unusual aspects of\nthe dynamics of active phase segregation, such as (i) anomalous growth\ndynamics, (ii) coarsening accompanied by propulsion and coalescence of domains\nthat exhibit nonreciprocal effects, (iii) segregation into mesoscale domains,\n(iv) emergence of a nonequilibrium phase segregated steady state characterised\nby strong macroscopic fluctuations (fluctuation dominated phase ordering\n(FDPO)), and (v) mesoscale segregation even above the equilibrium Tc. Apart\nfrom its implications for actively driven segregation of binary fluids, these\nideas are at the heart of an Active Emulsion description of the lateral\norganisation of molecules on the plasma membrane of living cells, whose full\nmolecular elaboration appears elsewhere.",
        "positive": "A model for the erosion onset of a granular bed sheared by a viscous\n  fluid: We study theoretically the erosion threshold of a granular bed forced by a\nviscous fluid. We first introduce a novel model of interacting particles driven\non a rough substrate. It predicts a continuous transition at some threshold\nforcing $\\theta_c$, beyond which the particle current grows linearly $J\\sim\n\\theta-\\theta_c$, in agreement with experiments. The stationary state is\nreached after a transient time $t_{\\rm conv}$ which diverges near the\ntransition as $t_{\\rm conv}\\sim |\\theta-\\theta_c|^{-z}$ with $z\\approx 2.5$.\nThe model also makes quantitative testable predictions for the drainage\npattern: the distribution $P(\\sigma)$ of local current is found to be extremely\nbroad with $P(\\sigma)\\sim J/\\sigma$, spatial correlations for the current are\nnegligible in the direction transverse to forcing, but long-range parallel to\nit. We explain some of these features using a scaling argument and a mean-field\napproximation that builds an analogy with $q$-models. We discuss the\nrelationship between our erosion model and models for the depinning transition\nof vortex lattices in dirty superconductors, where our results may also apply."
    },
    {
        "anchor": "Thermostatistics of a single particle on a granular dimer lattice:\n  influence of defects: We study the thermostatistical fluctuations of a single Delrin monomer on a\ngranular lattice of dimer particles using both experiment and simulation. The\ngoal is to examine the collision frequency, energy injection, and sidewall\neffects on a single second-layer particle in a bi-layer granular gas\nexperiment. Non-Gaussian velocity statistics are observed for the single\nparticle of the top layer and result from the presence of defects in the first\nlayer. These deviations are not directly due to the presence of the boundary\nwall, since the form of velocity distributions is quite spatially homogeneous,\nbut are the consequence of the presence of a few mobile defects in the first\nlayer.",
        "positive": "Metachronal coordination at the mesoscale: In nature, metachronal coordination is an efficient strategy for fluid\npumping and self-propulsion. Yet, mimetic systems for this type of organization\nare scarce. Recently, metachronal motion was observed in a bead-based\nmagnetocapillary mesoswimmer, but the mechanism of such device's behavior\nremained unclear. Here, we combine theory and experiments to explain two\nswimming regimes that we identify by modulation of the driving frequency. In\nthe linear, low-frequency regime, the swimmer motion originates from individual\nbead rotations. However, the high-frequency, metachronal regime is dominated by\ndeformations of the device near a mechanical resonance, which highlights the\nrole of bead inertia for optimized self-propulsion."
    },
    {
        "anchor": "Kinetic pathways of multi-phase surfactant systems: The relaxation following a temperature quench of two-phase (lamellar and\nsponge phase) and three-phase (lamellar, sponge and micellar phase) samples,\nhas been studied in an SDS/octanol/brine system. In the three-phase case we\nhave observed samples that are initially mainly sponge phase with lamellar and\nmicellar phase on the top and bottom respectively. Upon decreasing temperature\nmost of the volume of the sponge phase is replaced by lamellar phase. During\nthe equilibriation we have observed three regimes of behaviour within the\nsponge phase: (i) disruption in the sponge texture, then (ii) after the sponge\nphase homogenises there is a lamellar nucleation regime and finally (iii) a\nbizarre plume connects the lamellar phase with the micellar phase. The\nrelaxation of the two-phase sample proceeds instead in two stages. First\nlamellar drops nucleate in the sponge phase forming a onion `gel' structure.\nOver time the lamellar structure compacts while equilibriating into a two phase\nlamellar/sponge phase sample. We offer possible explanatioins for some of these\nobservations in the context of a general theory for phase kinetics in systems\nwith one fast and one slow variable.",
        "positive": "Anomalous diffusion of a tethered membrane: A Monte Carlo investigation: Using a continuum bead-spring Monte Carlo model, we study the anomalous\ndiffusion dynamics of a self-avoiding tethered membrane by means of extensive\ncomputer simulations. We focus on the subdiffusive stochastic motion of the\nmembrane's central node in the regime of flat membranes at temperatures above\nthe membrane folding transition. While at times, larger than the characteristic\nmembrane relaxation time $\\tau_R$, the mean-square displacement of the center\nof mass of the sheet, $<R_c^2>$, as well as that of its central node,\n$<R_n^2>$, show the normal Rouse diffusive behavior with a diffusion\ncoefficient $D_N$ scaling as $D_N \\propto N^{-1}$ with respect to the number of\nsegments $N$ in the membrane, for short times $t\\le \\tau_R$ we observe a {\\em\nmultiscale dynamics} of the central node, $<R_n^2> \\propto t^\\alpha$, where the\nanomalous diffusion exponent $\\alpha$ changes from $\\alpha \\approx 0.86$ to\n$\\alpha \\approx 0.27$, and then to $\\alpha \\approx 0.5$, before diffusion turns\neventually to normal. By means of simple scaling arguments we show that our\nmain result, $\\alpha \\approx 0.27$, can be related to particular mechanisms of\nmembrane dynamics which involve different groups of segments in the membrane\nsheet. A comparative study involving also linear polymers demonstrates that the\ndiffusion coefficient of self-avoiding tethered membranes, containing $N$\nsegments, is three times smaller than that of linear polymer chains with the\nsame number of segments."
    },
    {
        "anchor": "Third-generation cylindrical dendrimers based on L-aspargic acid in\n  solutions: hydrodynamic and electrooptical properties: Samples of third-generation cylindrical dendrimers with molar masses ranging\nin the interval 20000...60000 have been studied by the methods of equilibrium\nand non-equilibrium electrical birefringence, molecular hydrodynamics and\noptics. It was found that the absolute values of Kerr and flow birefringence\nconstants exceed the values obtained for analogous dendrimers of lower\ngenerations. The mechanism of reorientation has proven to be strongly dependent\non the physical and chemical properties of the solvent. In chloroform\nsolutions, the studied dendrimers align to the microwave-frequency electric\nfields according to large-scale mechanism. In dichloroacetic acid solutions,\nthe observed reorientation mechanism is low-scale, which is explained by\ndegradation of intermolecular hydrogen bonds. Terminal dendritic substituents\nof the macromolecules have experimentally proven to be oriented mainly along\nthe primary polymer chain.",
        "positive": "Role of three-body interactions in formation of bulk viscosity in liquid\n  argon: With the aim of locating the origin of discrepancy between experimental and\ncomputer simulation results on bulk viscosity of liquid argon, a molecular\ndynamic simulation of argon interacting via ab initio pair potential and\ntriple-dipole three-body potential has been undertaken. Bulk viscosity,\nobtained using Green-Kubo formula, is different from the values obtained from\nmodeling argon using Lennard-Jones potential, the former being closer to the\nexperimental data. The conclusion is made that many-body inter-atomic\ninteraction plays a significant role in formation of bulk viscosity."
    },
    {
        "anchor": "Elongation/Compaction of Giant DNA Caused by Depletion Interaction with\n  a Flexible Polymer: Structural changes in giant DNA induced by the addition of the flexible\npolymer PEG were examined by the method of single-DNA observation. In dilute\nDNA conditions, individual DNA assumes a compact state via a discrete\ncoil-globule transition, whereas in concentrated solution, DNA molecules\nexhibit an extended conformation via macroscopic phase segregation. The long\naxis length of the stretched state in DNA is about 1000 times larger than that\nof the compact state. Phase segregation at high DNA concentrations occurs at\nlower PEG concentrations than the compaction at low DNA concentrations. These\nopposite changes in the conformation of DNA molecule are interpreted in terms\nof the free energy, including depletion interaction.",
        "positive": "Shear-enhanced Liquid Crystal Spinning of Conjugated Polymer Fibers: Conjugated polymer fibers can be used to manufacture various soft fibrous\noptoelectronic devices, significantly advancing wearable devices and smart\ntextiles. Recently, conjugated polymer-based fibrous electronic devices have\nbeen widely used in energy conversion, electrochemical sensing, and\nhuman-machine interaction. However, the insufficient mechanical properties of\nconjugated polymer fibers, the difficulty in solution processing semiconductors\nwith rigid main chains, and the challenges in large-scale continuous production\nhave limited their further development in the wearable field. We regulated the\npi - pi stacking interactions in conjugated polymer molecules below their\ncritical liquid crystal concentration by applying fluid shear stress. We\nimplemented secondary orientation, leading to the continuous fabrication of\nanisotropic semiconductor fibers. This strategy enables conjugated polymers\nwith rigid backbones to synergistically enhance the mechanical and\nsemiconductor properties of fibers through liquid crystal spinning.\nFurthermore, conjugated polymer fibers, exhibiting excellent electrochemical\nperformance and high mechanical strength (600 MPa) that essentially meet the\nrequirements for industrialized preparation, maintain stability under extreme\ntemperatures, radiation, and chemical reagents. Lastly, we have demonstrated\nlogic circuits using semiconductor fiber organic electrochemical transistors,\nshowcasing its application potential in the field of wearable fabric-style\nlogic processing. These findings confirm the importance of the liquid\ncrystalline state and solution control in optimizing the performance of\nconjugated polymer fibers, thus paving the way for developing a new generation\nof soft fiber semiconductor devices."
    },
    {
        "anchor": "Structure/property relationship of semi-crystalline polymer during\n  tensile deformation: A molecular dynamics approach: A coarse-grained molecular dynamics model of linear polyethylene-like polymer\nchain system was built to investigate the responds of structure and mechanical\nproperties during uniaxial deformation. The influence of chain length,\ntemperature, and strain rate were studied. The molecular dynamic tests showed\nthat yielding may governed by different mechanisms at temperatures above and\nbelow Tg. Melt-recrystallization was observed at higher temperature, and\ndestruction of crystal structures was observed at lower temperatures beyond\nyield point. While the higher temperature and lower strain rate have similar\neffects on mechanical properties. The correlated influences of time and\ntemperature in the microscopic structures are more complicated. The evolution\nof microscopic characteristics such as the orientation parameter, the bond\nlength, and the content of trans-trans conformation were calculated from the\nsimulation. The results showed that the temperature have double effects on\npolymer chains. Higher temperature on one hand makes the chains more flexible,\nwhile on the other hand shortens the relaxation time of polymers. It is the\ninteraction of these two aspects that determine the orientation parameter.\nDuring deformation, the trans conformation has experienced a rising process\nafter the first drop process. And these microscopic structure parameters\nexhibit critical transaction, which are closely related to the yield point. A\nhypothetical model was thus proposed to describe the micro-structure and\nproperty relations based the investigations of this study.",
        "positive": "Electroneutrality breakdown for electrolytes embedded in varying-section\n  nanopores: We determine the local charge dynamics of a $z-z$ electrolyte embedded in a\nvarying-section channel. By means of an expansion based on the length scale\nseparation between the axial and transverse direction of the channel, we derive\nclosed formulas for the local excess charge for both, dielectric and conducting\nwalls, in $2D$ (planar geometry) as well as in $3D$ (cylindrical geometry). Our\nresults show that, even at equilibrium, the local charge electroneutrality is\nbroken whenever the section of the channel is not homogeneous for both\ndielectric and conducting walls as well as for $2D$ and $3D$ channels.\nInterestingly, even within our expansion, the local excess charge in the fluid\ncan be comparable to the net charge on the walls. We critically discuss the\nonset of such local electroneutrality breakdown in particular with respect to\nthe correction that it induces on the effective free energy profile experienced\nby tracer ions."
    },
    {
        "anchor": "Writhing Geometry at Finite Temperature: Random Walks and Geometric\n  phases for Stiff Polymers: We study the geometry of a semiflexible polymer at finite temperatures. The\nwrithe can be calculated from the properties of Gaussian random walks on the\nsphere. We calculate static and dynamic writhe correlation functions. The\nwrithe of a polymer is analogous to geometric or Berry phases studied in optics\nand wave mechanics. Our results can be applied to confocal microscopy studies\nof stiff filaments and to simulations of short DNA loops",
        "positive": "The longitudinal spin relaxation of 2D electrons in Si/SiGe quantum\n  wells in a magnetic field: The longitudinal spin relaxation time, T1, in a Si/SiGe quantum well is\ndetermined from the saturation of the ESR signal. We find values of a few\nmicroseconds. Investigations of T1 as a function of Fermi energy, concentration\nof scattering centers and of the momentum scattering time lead to the\nconclusion that for high electron mobility the spin relaxation is ruled by the\nDyakonov-Perel (DP) mechanism while for low mobility the Elliott-Yaffet\nmechanism dominates. The DP relaxation is caused by Bychkov-Rashba coupling.\nEvaluation of the DP mechanism shows that 1/T1 for high electron mobility can\nbe effectively reduced by an external magnetic field. The effect of the\ndegenerate Fermi-Dirac statistics on the DP process is discussed."
    },
    {
        "anchor": "A new kinetic theory model of granular flows that incorporates particle\n  stiffness: Granular materials are characterized by large collections of discrete\nparticles of sizes larger than one micron, where the particle-particle\ninteractions are significantly more important than the particle-fluid\ninteractions. These flows can be successfully modeled by the existing Kinetic\nTheory (KT) models when they are in the dilute regime with low\nparticle-particle collision frequencies, yielding results that agree well with\nthe simulation results of the event-driven hard sphere model or the more\nsophisticated soft-sphere Discrete Element Method (DEM). However, these KT\nmodels become less accurate for granular flows with soft particles (low\nparticle stiffness) at high particle-particle collision frequencies when the\npredicted collision interval (the time of free flight for a particle prior to\nthe next collision) is comparable to the collision duration; there is a large\ndiscrepancy between the results of these KT models and those from the DEM\nmodels. In this work we develop a new KT model that could be used to model\ngranular systems of high collision frequencies with a finite particle\nstiffness. This is done by modifying the fluctuation energy dissipation rate to\nincorporate the ratio of collision duration to collision interval, a parameter\nthat is determined by both the collision frequency and particle stiffness. We\nuse a linear-spring-dashpot collision scheme to model the elastic potential\nenergy in the system and to uncover the relationship between the constitutive\nrelations of KT and the ratio of collision duration to collision interval.",
        "positive": "Spiral Thermal Waves Generated by Self-Propelled Camphor Boats: Spiral thermal surface waves arising from self-propulsion of the\ncamphor-driven objects are reported. Spiral thermal waves were registered for\nthe dissolution and evaporation-guided self-propulsion. Soluto-capillarity is\naccompanied by thermo-capillarity under self-propulsion of camphor boats. The\njump in the surface tension due to the soluto-capillarity is much larger than\nthat due to the thermo-capillarity. The observed thermal effect is related to\nthe adsorption of camphor molecules at the water/vapor interface. The observed\nspirals are shaped as Archimedean ones."
    },
    {
        "anchor": "Sedimentation of active colloidal suspensions: In this paper, we investigate experimentally the non-equilibrium steady state\nof an active colloidal suspension under gravity field. The active particles are\nmade of chemically powered colloids, showing self propulsion in the presence of\nan added fuel, here hydrogen peroxide. The active suspension is studied in a\ndedicated microfluidic device, made of permeable gel microstructures. Both the\nmicrodynamics of individual colloids and the global stationary state of the\nsuspension under gravity - density profiles, number fluctuations - are measured\nwith optical microscopy. This allows to connect the sedimentation length to the\nindividual self-propelled dynamics, suggesting that in the present dilute\nregime the active colloids behave as 'hot' particles. Our work is a first step\nin the experimental exploration of the out-of-equilibrium properties of\nartificial active systems.",
        "positive": "Effect of size polydispersity on the pitch of nanorod cholesterics: Many nanoparticle-based chiral liquid crystals are composed of polydisperse\nrod-shaped particles with considerable spread in size or shape, affecting the\nmesoscale chiral properties in, as yet, unknown ways. Using an algebraic\ninterpretation of Onsager-Straley theory for twisted nematics, we investigate\nthe role of length polydispersity on the pitch of nanorod-based cholesterics\nwith a continuous length polydispersity, and find that polydispersity enhances\nthe twist elastic modulus, $K_{2}$, of the cholesteric material without\naffecting the effective helical amplitude, $K_{t}$. In addition, for the\ninfinitely large average aspect ratios considered here, the dependence of the\npitch on the overall rod concentration is completely unaffected by\npolydispersity. For a given concentration, the increase in twist elastic\nmodulus (and reduction of the helical twist) may be up to 50% for strong size\npolydispersity, irrespective of the shape of the unimodal length distribution.\nWe also demonstrate that the twist reduction is reinforced in bimodal\ndistributions, by doping a polydisperse cholesteric with very long rods.\nFinally, we identify a subtle, non-monotonic change of the pitch across the\nisotropic-cholesteric biphasic region."
    },
    {
        "anchor": "Self-organized states of solutions of active ring polymers in bulk and\n  under confinement: In the presented work we study, by means of numerical simulations, the\nbehaviour of a suspension of active ring polymers in the bulk and under lateral\nconfinement. When changing the separation between the confining planes and the\npolymers' density, we detect the emergence of a self-organised dynamical state,\ncharacterised by the coexistence of slowly diffusing clusters of rotating disks\nand faster rings moving in between them. This system represents a peculiar case\nat the crossing point between polymer, liquid crystals and active matter\nphysics, where the interplay between activity, topology and confinement leads\nto a spontaneous segregation of a one component solution.",
        "positive": "Crystal-liquid interfacial free energy via thermodynamic integration: A novel thermodynamic integration (TI) scheme is presented to compute the\ncrystal-liquid interfacial free energy ($\\gamma_{\\rm cl}$) from molecular\ndynamics simulation. The scheme is applied to a Lennard-Jones system. By using\nextremely short-ranged and impenetrable Gaussian flat walls to confine the\nliquid and crystal phases, we overcome hysteresis problems of previous TI\nschemes that stem from the translational movement of the crystal-liquid\ninterface. Our technique is applied to compute $\\gamma_{\\rm cl}$ for the (100),\n(110) and (111) orientation of the crystalline phase at three temperatures\nunder coexistence conditions. For one case, namely the (100) interface at the\ntemperature $T=1.0$ (in reduced units), we demonstrate that finite-size scaling\nin the framework of capillary wave theory can be used to estimate $\\gamma_{\\rm\ncl}$ in the thermodynamic limit. Thereby, we show that our TI scheme is not\nassociated with the suppression of capillary wave fluctuations."
    },
    {
        "anchor": "Fluidization of granular media wetted by liquid $^4$He: We explore experimentally the fluidization of vertically agitated PMMA\nspheres wetted by liquid $^4$He. By controlling the temperature around the\n$\\lambda$ point we change the properties of the wetting liquid from a normal\nfluid (helium I) to a superfluid (helium II). For wetting by helium I, the\ncritical acceleration for fluidization ($\\Gamma_c$) shows a steep increase\nclose to the saturation of the vapor pressure in the sample cell. For helium II\nwetting, $\\Gamma_c$ starts to increase at about 75% saturation, indicating that\ncapillary bridges are enhanced by the superflow of unsaturated helium film.\nAbove saturation, $\\Gamma_c$ enters a plateau regime where the capillary force\nbetween particles is independent of the bridge volume. The plateau value is\nfound to vary with temperature and shows a peak at 2.1 K, which we attribute to\nthe influence of the specific heat of liquid helium.",
        "positive": "The role of the Havriliak-Negami relaxation in the description of local\n  structure of Kohlrausch's function in the frequency domain. Part II: The suitability of a double Havriliak-Negami (HN) approximant to represent\nthe Fourier Transform of the time derivative of Kohlrausch-Williams-Watts\nfunction, -\\psi_{\\beta}, has been discussed in the first part of this work.\nThere, it is established the local character of the approximation and how, with\nslight variation of the parameters\n\\{\\alpha_{1,2},\\gamma_{1,2},\\tau_{1,2},\\lambda\\} with frequency, Ap_{2}HN can\ndescribe a perfect fit with the objective function, \\psi_{\\beta}. Such\nadiabatic behavior is commonly misunderstood as an argument against the\napproximation by means of basic relaxation functions as Havriliak-Negami; this\nfact it is best interpreted as the need for a wider family of relaxations with\na known local portrayal.\n  Two new sets of models for describing compactly the Fourier Transform of\nKohlrausch-Williams-Watts are proposed, both based on the adiabatic variation\nof parameters of a double Havriliak-Negami approximation along the whole\ninterval of frequencies. The first one is relying, obviously, on the use of a\nwell-behaved-pair of patches of the mentioned type of approximants,\n\\mathcal{A}p_{2}HN(\\omega). The second is obtained by altering the simple\nfunctions HN(\\omega) and making dissimilar the couple. They are proposed the\nguidelines of a new and systematic approach with extended Havriliak-Negami\nfunctions which is global, (non local), and of constant parameters. The latter\nat the cost of a more complicated dependency with the low frequencies than\n1+(i\\omega\\tau_{HN})^{\\alpha}."
    },
    {
        "anchor": "Confinement-induced glassy dynamics in a model for chromosome\n  organization: Recent experiments showing scaling of the intrachromosomal contact\nprobability, $P(s)\\sim s^{-1}$ with the genomic distance $s$, are interpreted\nto mean a self-similar fractal-like chromosome organization. However, scaling\nof $P(s)$ varies across organisms, requiring an explanation. We illustrate\ndynamical arrest in a highly confined space as a discriminating marker for\ngenome organization, by modeling chromosome inside a nucleus as a homopolymer\nconfined to a sphere of varying sizes. Brownian dynamics simulations show that\nthe chain dynamics slows down as the polymer volume fraction ($\\phi$) inside\nthe confinement approaches a critical value $\\phi_c$. The universal value of\n$\\phi_c^{\\infty}\\approx 0.44$ for a sufficiently long polymer ($N\\gg 1$) allows\nus to discuss genome dynamics using $\\phi$ as a single parameter. Our study\nshows that the onset of glassy dynamics is the reason for the segregated\nchromosome organization in human ($N\\approx 3\\times 10^9$,\n$\\phi\\gtrsim\\phi_c^{\\infty}$), whereas chromosomes of budding yeast ($N\\approx\n10^8$, $\\phi<\\phi_c^{\\infty}$) are equilibrated with no clear signature of such\norganization.",
        "positive": "Printing Flowers? Custom-tailored Photonic Cellulose Films with\n  Engineered Surface Topography: Wrought by nature's wondrous hand, surface topographies are discovered on all\nlength scales in living creatures and serve a variety of functions. Inspired by\nfloral striations, here we developed a scalable means of fabricating\ncustom-tailored photonic cellulose films that contained both cholesteric\norganization and microscopic wrinkly surface topography. Free-standing films\nwere prepared by molding cellulose nanocrystal ink onto an oriented wrinkled\ntemplate through evaporation-assisted nanoimprinting lithography, yielding\nmorphology-induced light scattering at a short wavelength as well as optically\ntunable structural color derived from the helical cellulose matrix. As a\nresult, the interplay between the two photonic structures, grating-like surface\nand chiral bulk, led to selective scattering of circularly polarized light with\nspecific handedness. Moreover, the wrinkled surface relief on cholesteric\ncellulose films could be precisely controlled, enabling engineered printing of\nmicroscopic patterned images."
    },
    {
        "anchor": "Spontaneous jamming and unjamming in a hopper with multiple exit\n  orifices: We show that the flow of granular material inside a 2-dimensional flat\nbottomed hopper is altered significantly by having more than one exit orifice.\nFor the hoppers with small orifice widths, inter-mittent flow through one\norifice enables the resumption of flow through the adjacent jammed orifice,\nthus displaying a sequence of jamming and unjamming events. Using discrete\nelement simulations, we show that the total amount of granular material (i.e.\navalanche size) emanating from all the orifices combined can be enhanced by\nabout an order of magnitude difference by simply adjusting the inter-orifice\ndistance. The unjamming is driven primarily by fluctuations alone when the\ninter-orifice distance is large, but when the orifices are brought close\nenough, the fluctuations along with the mean flow cause the flow unjamming.",
        "positive": "Capturing the slow relaxation time of superparamagnetic colloids in\n  time-varying fields: Superparamagnetic colloids present interesting assembly dynamics and\npropulsion in time-varying magnetic fields due to their magnetic relaxation.\nHowever, little is known about the mechanisms governing this magnetic\nrelaxation, which is commonly attributed to the interactions and polydispersity\nof the ferromagnetic nanoparticles distributed within the colloid. We measure\nthis relaxation from the effective potential between colloids subjected to\nrotating magnetic fields. Remarkably, our results indicate the presence of\nmagnetic relaxation times much longer than what has been reported, which\nfurthers our understanding of the magnetization of colloids in complex magnetic\nfields."
    },
    {
        "anchor": "Role of shape in particle-lipid membrane interactions: from surfing to\n  full engulfment: Understanding and manipulating the interactions between foreign bodies and\ncell membranes during endo- and phagocytosis is of paramount importance, not\nonly for the fate of living cells but also for numerous biomedical\napplications. This study aims to elucidate the role of variables such as\nanisotropic particle shape, curvature, orientation, membrane tension, and\nadhesive strength in this essential process, using a minimal experimental\nbiomimetic system comprising giant unilamellar vesicles and rod-like particles\nwith different curvatures and aspect ratios. We find that the particle wrapping\nprocess is dictated by the balance between the elastic energy penalty and\nadhesion energy gain, leading to two distinct engulfment pathways, tip-first\nand side-first, emphasizing the significance of the particle orientation in\ndetermining the pathway. Moreover, our experimental results are consistent with\ntheoretical predictions in a state diagram, showcasing how to control the\nwrapping pathway from surfing to partial to complete wrapping by the interplay\nbetween membrane tension and adhesive strength. At moderate particle\nconcentrations, we observed the formation of rod clusters, which exhibited\ncooperative and sequential wrapping. Our study not only contributes to a\ncomprehensive understanding of the mechanistic intricacies of endocytosis by\nhighlighting how the interplay between the anisotropic particle shape,\ncurvature, orientation, membrane tension, and adhesive strength can influence\nthe engulfment pathway but also provides a foundational base for future\nresearch in the field.",
        "positive": "Flowing emulsions through disorder: Critical depinning and smectic\n  rivers: During the past sixty minutes only, oil companies have extracted six\ntrillions liters of oil from the ground, i.e. the volume of about two hundreds\nOlympic swimming pools. This phenomenal number gives a striking illustration of\nthe impact of multiphase flows on the world economy and environment. From a\nfundamental perspective, we now clearly understand the large-scale patterns\nformed when liquid interfaces are driven through heterogeneous environments. In\nstark contrast, the displacement of fragmented fluids through disordered media\nremains limited to isolated droplets and bubbles. Here, we elucidate the\ncollective dynamics of emulsions hydrodynamically driven through disordered\nenvironments. Advecting hundreds of thousands of microfluidic droplets through\nrandom lattices of pinning sites, we establish that the mobilization of\nconfined emulsions is a critical dynamical transition. Unlike contact-line\ndepinning, emulsion mobilization is not triggered by large-scale avalanches but\nmerely requires the coordinated motion of small groups of particles.\nCriticality arises from the correlations of seemingly erratic depinning events\nover system-spanning scales along smectic river networks. We elucidate the\nmicroscopic origin of these self-organized flow patterns: contact interactions\nand hydrodynamic focusing conspire to mobilize emulsion out of disorder. We\nclose our article commenting on the similarities (and profound differences)\nwith the plastic depinning transitions of driven flux lines in high-$T_{\\rm c}$\nsuperconductors, and grain transport in eroded sand beds."
    },
    {
        "anchor": "Periodic-cylinder vesicle with minimal energy: We give some details about the periodic cylindrical solution found by Zhang\nand Ou-Yang in [Phys. Rev. E 53, 4206(1996)] for the general shape equation of\nvesicle. Three different kinds of periodic cylindrical surfaces and a special\nclosed cylindrical surface are obtained. Using the elliptic functions contained\nin \\emph{mathematic}, we find that this periodic shape has the minimal total\nenergy for one period when the period-amplitude ratio $\\beta\\simeq1.477$, and\npoint out that it is a discontinuous deformation between plane and this\nperiodic shape. Our results also are suitable for DNA and multi-walled carbon\nnanotubes (MWNTs)",
        "positive": "Limits of validity for a semiclassical mean-field two-fluid model for\n  Bose-Einstein condensation thermodynamics: We reinvestigate the Bose-Einstein condensation (BEC) thermodynamics of a\nweakly interacting dilute Bose gas under the action of a trap using a\nsemiclassical two-fluid mean-field model in order to find the domain of\napplicability of the model. Such a model is expected to break down once the\ncondition of diluteness and weak interaction is violated. We find that this\nbreakdown happens for values of coupling and density near the present\nexperimental scenario of BEC. With the increase of the interaction coupling and\ndensity the model may lead to unphysical results for thermodynamic observables."
    },
    {
        "anchor": "Electroosmosis as a probe for electrostatic correlations: We study the role of ionic correlations on the electroosmotic flow in planar\ndouble-slit channels, without salt. We propose an analytical theory, based on\nrecent advances in the understanding of correlated systems. We compare the\ntheory with mean-field results and validate it by means of dissipative particle\ndynamics simulations. Interestingly, for some surface separations, correlated\nsystems exhibit a larger flow than predicted by mean-field. We conclude that\nthe electroosmotic properties of a charged system can be used, in general, to\ninfer and weight the importance of electrostatic correlations therein.",
        "positive": "Motion in a Bose condensate: IX. Crow instability of antiparallel vortex\n  pairs: The Gross-Pitaevskii (GP) equation admits a two-dimensional solitary wave\nsolution representing two mutually self-propelled, anti-parallel straight line\nvortices. The complete sequence of such solitary wave solutions has been\ncomputed by Jones and Roberts (J. Phys. A, 15, 2599, 1982). These solutions are\nunstable with respect to three-dimensional perturbations (the Crow\ninstability). The most unstable mode has a wavelength along the direction of\nthe vortices of the same order as their separation. The growth rate associated\nwith this mode is evaluated here, and it is found to increase very rapidly with\ndecreasing separation. It is shown, through numerical integrations of the GP\nequation that, as the perturbations grow to finite amplitude, the lines\nreconnect to produce a sequence of almost circular vortex rings."
    },
    {
        "anchor": "Random sequential adsorption of partially ordered discorectangles onto a\n  continuous plane: Computer simulation was used to study the random sequential adsorption of\nidentical discorectangles onto a continuous plane . The problem was analyzed\nfor a wide range of discorectangle aspect ratios ($\\varepsilon \\in [1;100]$).\nWe studied anisotropic deposition, i.e., the orientations of the deposited\nparticles were uniformly distributed within some interval such that the\nparticles were preferentially aligned along a given direction. The kinetics of\nthe changes in the packing density $\\varphi$ found at different values of $S_0$\nare discussed. Partial ordering of the discorectangles significantly affected\nthe packing density at the jamming state, $\\varphi_\\text{j}$, and shifted the\ncusps in the $\\varphi_\\text{j}(\\varepsilon)$ dependencies. The structure of the\njammed state was analyzed using the adsorption of disks of different diameters\ninto the porous space between the deposited discorectangles. The analysis of\nthe connectivity between the discorectangles was performed assuming a\ncore---shell structure of particles.",
        "positive": "Physics of polymer melts: A novel perspective: We have mapped the physics of polymer melts onto a time-dependent\nLandau-Ginzburg $|\\psi|^4$ field theory using techniques of functional\nintegration. Time in the theory is simply a label for the location of a given\nmonomer along the extent of a flexible chain. With this model, one can show\nthat the limit of infinitesimal concentration of a polymer melt corresponds to\na {\\em dynamic} critical phenomenon. The transition to the entangled state is\nalso shown to be a critical point. For larger concentrations, when the role of\nfluctuations is reduced, a mean field approximation is justifiably employed to\nshow the existence of tube-like structures reminiscent of Edwards' model."
    },
    {
        "anchor": "Effect of Intrinsic Curvature on Semiflexible Polymers: Recently many important biopolymers have been found to possess intrinsic\ncurvature. Tubulin protofilaments in animal cells, FtsZ filaments in bacteria\nand double stranded DNA are examples. We examine how intrinsic curvature\ninfluence the conformational statistics of such polymers. We give exact results\nfor the tangent-tangent spatial correlation function C(r) = t(s).t(s + r), both\nin two and three dimensions. Contrary to expectation, C(r) does not show any\noscillatory behavior, rather decays exponentially and the effective persistence\nlength has strong length dependence for short polymers. We also compute the\ndistribution function P(R) of the end to end distance R and show how curved\nchains can be distinguihed from WLC using loop formation probability.",
        "positive": "Drastic reduction of dynamic liquid-solid friction in supercooled\n  glycerol: This study addresses the influence of internal liquid dynamics on\nliquid-solid friction. Taking advantage of the wide range of relaxation\ntimescales in supercooled liquids, we use a tuning-fork-based AFM to measure\nthe slippage of supercooled glycerol on mica at 30 kHz. We report a 2-order of\nmagnitude increase of slippage with decreasing temperature by only 30{\\deg}C.\nMore importantly, as the bulk liquid dynamics are slowed with decreasing\ntemperature, we report a sharp drop of the interfacial friction coefficient in\ncontrast with the usual assumption of thermally activated interfacial dynamics.\nTo rationalize this original behavior, we account for the contribution of solid\nfluctuations to liquid friction. We show that a minimalistic single\nphonon-branch model of the mica surface yields semi-quantitative agreement with\nour measurements. In this picture, the liquid's relaxation rate is the tuning\nknob between two friction regimes where the wall is seen either as a static\ncorrugated potential or as a thermally fluctuating surface. Remarkably, this\nstudy bridges soft and hard condensed matter: hydrodynamic flow controlled by\nthe solid's dynamical modes."
    },
    {
        "anchor": "Topological origin of strain induced damage of multi-network elastomers\n  by bond breaking: Elastomers that can sustain large reversible strain are essential components\nfor stretchable electronics. The stretchability and mechanical robustness of\nunfilled elastomers can be enhanced by introducing easier-to-break cross-links,\ne.g. through the multi-network structure, which also causes stress-strain\nhysteresis indicating strain-induced damage. However, it remains unclear\nwhether cross-link breakage follows a predictable pattern that can be used to\nunderstand the damage evolution with strain. Using coarse-grained molecular\ndynamics and topology analyses of the polymer network, we find that\nbond-breaking events are controlled by the evolution of the global shortest\npath length between well-separated cross-links, which is both anisotropic and\nhysteretic with strain. These findings establish an explicit connection between\nthe molecular structure and the macroscopic mechanical behavior of elastomers,\nthereby providing guidelines for designing mechanically robust soft materials.",
        "positive": "Crystallisation of soft matter under confinement at interfaces and in\n  wedges: The surface freezing and surface melting transitions exhibited by a model\ntwo-dimensional soft matter system is studied. The behaviour when confined\nwithin a wedge is also considered. The system consists of particles interacting\nvia a soft purely repulsive pair potential. Density functional theory (DFT) is\nused to calculate density profiles and thermodynamic quantities. The external\npotential due to the confining walls is modelled via a hard-wall with an\nadditional repulsive Yukawa potential. The surface phase behaviour depends on\nthe range and strength of this repulsion: When the repulsion strength is weak,\nthe wall promotes freezing at the surface of the wall. The thickness of this\nfrozen layer grows logarithmically as the bulk liquid-solid phase coexistence\nis approached. Our mean-field DFT predicts that this crystalline layer at the\nwall must be nucleated (i.e. there is a free energy barrier) and its formation\nis necessarily a first-order transition, referred to as `prefreezing', by\nanalogy with the prewetting transition. However, in contrast to the latter,\nprefreezing cannot terminate in a critical point, since the phase transition\ninvolves a change in symmetry. If the wall-fluid interaction is sufficiently\nlong ranged and the repulsion is strong enough, surface melting can instead\noccur. Then the interface between the wall and the bulk crystalline solid\nbecomes wet by the liquid phase as the chemical potential is decreased towards\nthe value at liquid-solid coexistence. It is observed that the finite thickness\nfluid film at the wall has a broken translational symmetry due to its proximity\nto the bulk crystal and so the nucleation of the wetting film can be either\nfirst-order or continuous. Our mean-field theory predicts that for certain wall\npotentials there is a premelting critical point analogous to the surface\ncritical point for the prewetting transition. In a wedge..."
    },
    {
        "anchor": "Nonadditive hard-sphere fluid mixtures: A simple analytical theory: We construct a non-perturbative fully analytical approximation for the\nthermodynamics and the structure of nonadditive hard-sphere fluid mixtures. The\nmethod essentially lies in a heuristic extension of the Percus-Yevick solution\nfor additive hard spheres. Extensive comparison with Monte Carlo simulation\ndata shows a generally good agreement, especially in the case of like-like\nradial distribution functions.",
        "positive": "Active matter invasion of a viscous fluid: unstable sheets and a no-flow\n  theorem: We investigate the dynamics of a dilute suspension of hydrodynamically\ninteracting motile or immotile stress-generating swimmers or particles as they\ninvade a surrounding viscous fluid. Colonies of aligned pusher particles are\nshown to elongate in the direction of particle orientation and undergo a\ncascade of transverse concentration instabilities, governed at small times by\nan equation which also describes the Saffman-Taylor instability in a Hele-Shaw\ncell, or Rayleigh-Taylor instability in two-dimensional flow through a porous\nmedium. Thin sheets of aligned pusher particles are always unstable, while\nsheets of aligned puller particles can either be stable (immotile particles),\nor unstable (motile particles) with a growth rate which is non-monotonic in the\nforce dipole strength. We also prove a surprising \"no-flow theorem\": a\ndistribution initially isotropic in orientation loses isotropy immediately but\nin such a way that results in no fluid flow everywhere and for all time."
    },
    {
        "anchor": "Dynamic clustering and re-dispersion in concentrated colloid-active gel\n  composites: We study the dynamics of quasi-two-dimensional concentrated suspensions of\ncolloidal particles in active gels by computer simulations. Remarkably, we find\nthat activity induces a dynamic clustering of colloids even in the absence of\nany preferential anchoring of the active nematic director at the particle\nsurface. When such an anchoring is present, active stresses instead compete\nwith elastic forces and re-disperse the aggregates observed in passive\ncolloid-liquid crystal composites. Our quasi-two-dimensional \"inverse\"\ndispersions of passive particles in active fluids (as opposed to the more\ncommon \"direct\" suspensions of active particles in passive fluids) provide a\npromising route towards the self-assembly of new soft materials.",
        "positive": "Temperature dependence of micelle shape transitions in copolymer\n  solutions: the role of inter-block incompatibility: The nature of the transition between worm-like and spherical micelles in\nblock copolymer dispersions varies between systems. In some formulations,\nheating drives a transition from worms to spheres, while in other systems the\nsame transition is induced by cooling. In addition, a sphere-worm\ninterconversion can be accompanied either by an increase or a decrease in the\nsolvation of the core, even if the direction of the temperature dependence is\nthe same. Here, self-consistent field theory is used to provide a potential\nexplanation of this range of behaviour. Specifically, we show that, within this\nmodel, the dependence of the transition on the incompatibility $\\chi_{BS}$ of\nthe solvophobic block B and the solvent S (the parameter most closely related\nto the temperature) is strongly influenced by the incompatibility $\\chi_{AB}$\nbetween B and the solvophilic block A. When $\\chi_{AB}$ is small ($\\chi_{AB}\\le\n0.1$), it is found that increasing $\\chi_{BS}$ produces a transition from\nworm-like micelles to spheres (or, more generally, from less curved to more\ncurved structures). When $\\chi_{AB}$ is above 0.1, increasing $\\chi_{BS}$\ndrives the system from spheres to worm-like micelles. Whether a transition is\nobserved within a realistic range of $\\chi_{BS}$ is also found to depend on the\nfraction of solvophilic material in the copolymer. The relevance of our\ncalculations to experimental results is discussed, and we suggest that the\ndirection of the temperature dependence may be controlled not only by the\nsolution behaviour of the solvophobic block (upper critical solution\ntemperature versus lower critical solution temperature) but also by\n$\\chi_{AB}$."
    },
    {
        "anchor": "Climbing two hills is faster than one: collective barrier-crossing by\n  colloids driven through a microchannel: Ohm's law is one of the most central transport rules stating that the total\nresistance of sequential single resistances is additive. While this rule is\nmost commonly applied to electronic circuits, it also applies to other\ntransport phenomena such as the flow of colloids or nanoparticles through\nchannels containing multiple obstacles, as long as these obstacles are\nsufficiently far apart. Here we explore the breakdown of Ohm's law for fluids\nof repulsive colloids driven over two energetic barriers in a microchannel,\nusing real-space microscopy experiments, particle-resolved simulations, and\ndynamical density functional theory. If the barrier separation is comparable to\nthe particle correlation length, the resistance is highly non-additive, such\nthat the resistance added by the second barrier can be significantly higher or\nlower than that of the first. Surprisingly, in some cases the second barrier\ncan even add a {\\it negative} resistance, such that two identical barriers are\neasier to cross than a single one. We explain this counterintuitive observation\nin terms of the structuring of particles trapped between the barriers.",
        "positive": "An additive algorithm for origami design: Inspired by the allure of additive fabrication, we pose the problem of\norigami design from a new perspective: how can we grow a folded surface in\nthree dimensions from a seed so that it is guaranteed to be isometric to the\nplane? We solve this problem in two steps: by first identifying the geometric\nconditions for the compatible completion of two separate folds into a single\ndevelopable four-fold vertex, and then showing how this foundation allows us to\ngrow a geometrically compatible front at the boundary of a given folded seed.\nThis yields a complete marching, or additive, algorithm for the inverse design\nof the complete space of developable quad origami patterns that can be folded\nfrom flat sheets. We illustrate the flexibility of our approach by growing\nordered, disordered, straight and curved folded origami and fitting surfaces of\ngiven curvature with folded approximants. Overall, our simple shift in\nperspective from a global search to a local rule has the potential to transform\norigami-based meta-structure design."
    },
    {
        "anchor": "Low magnetic field induced capacitance changes in ferronematics: The response in capacitance to low external magnetic fields (up to 0.1 T) of\nsuspensions of spherical magnetic nanoparticles, single-wall carbon nanotubes\n(SWCNT), SWCNT functionalized with carboxyl group (SWCNT-COOH) and SWCNT\nfunctionalized with Fe$_3$O$_4$ nanoparticles in a nematic liquid crystal has\nbeen studied experimentally. The volume concentration of nanoparticles was\n$\\phi_1$ = 10$^{-4}$ and $\\phi_2$ = 10$^{-3}$. Independent of the type and the\nvolume concentration of the nanoparticles, a linear response to low magnetic\nfields (far below the magnetic Fr\\'eederiksz transition threshold) has been\nobserved, which is not present in the undoped nematic.",
        "positive": "Differential Colorimetry Measurements of Fluctuation Growth in Nanofilms\n  Exposed to Large Surface Thermal Gradients: Slender liquid nanofilms exposed to large surface thermal gradients are known\nto undergo thickness fluctuations which rapidly self-organize into arrays of\nnanoprotrusions with a separation distance of tens of microns. We previously\nreported good agreement between measurements of the characteristic spacing and\nthe wavelength of the most unstable mode predicted by a linear stability\nanalysis based on a long wavelength thermocapillary model. Here we focus on\ndifferential colorimetry measurements to quantify early time out-of-plane\ngrowth of protrusions for peak heights spanning 20 to 200 nm. Analysis of peak\nheights based on shape reconstruction reveals robust exponential growth. Good\nquantitative agreement of the growth rates with the thermocapillary model is\nobtained using a single fit constant to account for material parameters of\nnanofilms that could not be measured directly. These findings lend further\nsupport to the conjecture that the array protrusions uncovered almost two\ndecades ago stem from a linear instability whose growth rate is controlled by\nthermocapillary forces counterbalanced by capillary forces."
    },
    {
        "anchor": "Computing the linear viscoelastic properties of soft gels using an\n  Optimally Windowed Chirp protocol: We use molecular dynamics simulations of a model three-dimensional\nparticulate gel, to investigate the linear viscoelastic response. The numerical\nsimulations are combined with a novel test protocol (the optimally- windowed\nchirp or OWCh), in which a continuous exponentially-varying frequency sweep\nwindowed by a tapered cosine function is applied. The mechanical response of\nthe gel is then analyzed in the Fourier domain. We show that i) OWCh leads to\nan accurate computation of the full frequency spectrum at a rate significantly\nfaster than with the traditional discrete frequency sweeps, and with a\nreasonably high signal-to-noise ratio, and ii) the bulk viscoelastic response\nof the microscopic model can be described in terms of a simple mesoscopic\nconstitutive model. The simulated gel response is in fact well described by a\nmechanical model corresponding to a fractional Kelvin-Voigt model with a single\nScott-Blair (or springpot) element and a spring in parallel. By varying the\nviscous damping and the particle mass used in the microscopic simulations over\na wide range of values, we demonstrate the existence of a single master curve\nfor the frequency dependence of the viscoelastic response of the gel that is\nfully predicted by the constitutive model. By developing a fast and robust\nprotocol for evaluating the linear viscoelastic spectrum of these soft solids,\nwe open the path towards novel multiscale insight into the rheological response\nfor such complex materials.",
        "positive": "Tunable interactions between paramagnetic colloidal particles driven in\n  a modulated ratchet potential: We study experimentally and theoretically the interactions between\nparamagnetic particles dispersed in water and driven above the surface of a\nstripe patterned magnetic garnet film. An external rotating magnetic field\nmodulates the stray field of the garnet film and generates a translating\npotential landscape which induces directed particle motion. By varying the\nellipticity of the rotating field, we tune the inter-particle interactions from\nnet attractive to net repulsive. For attractive interactions, we show that\npairs of particles can approach each other and form stable doublets which\nafterwards travel along the modulated landscape at a constant mean speed. We\nmeasure the strength of the attractive force between the moving particles and\npropose an analytically tractable model that explains the observations and is\nin quantitative agreement with experiment."
    },
    {
        "anchor": "Incompressible polar active fluids with quenched disorder in dimensions\n  $d> 2$: We present a hydrodynamic theory of incompressible polar active fluids with\nquenched disorder. This theory shows that such fluids can overcome the\ndisruption caused by the quenched disorder and move coherently, in the sense of\nhaving a non-zero mean velocity in the hydrodynamic limit. However, the scaling\nbehavior of this class of active systems cannot be described by linearized\nhydrodynamics in spatial dimensions between 2 and 5. Nonetheless, we obtain the\nexact dimension-dependent scaling exponents in these dimensions.",
        "positive": "Scaling of hysteresis loop of interacting polymers under a periodic\n  force: Using Langevin Dynamics simulations, we study a simple model of\ninteracting-polymer under a periodic force. The force-extension curve strongly\ndepends on the magnitude of the amplitude $(F)$ and the frequency ($\\nu$) of\nthe applied force. In low frequency limit, the system retraces the\nthermodynamic path. At higher frequencies, response time is greater than the\nexternal time scale for change of force, which restrict the biomolecule to\nexplore a smaller region of phase space that results in hysteresis of different\nshapes and sizes. We show the existence of dynamical transition, where area of\nhysteresis loop approaches to a large value from nearly zero area with\ndecreasing frequency. The area of hysteresis loop is found to scale as\n$F^{\\alpha} \\nu^{\\beta}$ for the fixed length. These exponents are found to be\nthe same as of the mean field values for a time dependent hysteretic response\nto periodic force in case of the isotropic spin."
    },
    {
        "anchor": "Enumerating rigid sphere packings: Packing problems, which ask how to arrange a collection of objects in space\nto meet certain criteria, are important in a great many physical and biological\nsystems, where geometrical arrangements at small scales control behaviour at\nlarger ones. In many systems there is no single, optimal packing that\ndominates, but rather one must understand the entire set of possible packings.\nAs a step in this direction we enumerate rigid clusters of identical hard\nspheres for $n\\leq 14$, and clusters with the maximum number of contacts for\n$n\\leq 19$. A rigid cluster is one that cannot be continuously deformed while\nmaintaining all contacts. This is a nonlinear notion that arises naturally\nbecause such clusters are the metastable states when the spheres interact with\na short-range potential, as is the case in many nano- or micro-scale systems.\nWe expect these lists are nearly complete, except for a small number of highly\nsingular clusters (linearly floppy but nonlinearly rigid.) The data contains\nsome major geometrical surprises, such as the prevalence of hypostatic\nclusters: those with less than the $3n-6$ contacts generically necessary for\nrigidity. We discuss these and several other unusual clusters, whose geometries\nmay shed insight into physical mechanisms, pose mathematical and computational\nproblems, or bring inspiration for designing new materials.",
        "positive": "A minimal model for the inelastic mechanics of biopolymer networks and\n  cells: Live cells have ambiguous mechanical properties. They were often described as\neither elastic solids or viscoelastic fluids and have recently been classified\nas soft glassy materials characterized by weak power-law rheology. Nonlinear\nrheological measurements have moreover revealed a pronounced inelastic response\nindicative of a competition between stiffening and softening. It is an\nintriguing question whether these observations can be explained from the\nmaterial properties of much simpler in-vitro reconstituted networks of\nbiopolymers that serve as reduced model systems for the cytoskeleton. Here, we\nexplore the mechanism behind the inelastic response of cells and biopolymer\nnetworks, theoretically. Our analysis is based on the model of the inelastic\nglassy wormlike chain that accounts for the nonlinear polymer dynamics and\ntransient crosslinking in biopolymer networks. It explains how inelastic and\nkinematic-hardening type behavior naturally emerges from the antagonistic\nmechanisms of viscoelastic stress-stiffening due to the polymers and inelastic\nfluidization due to bond breaking. It also suggests a simple set of schematic\nconstitutive equations which faithfully reproduce the rich inelastic\nphenomenology of biopolymer networks and cells."
    },
    {
        "anchor": "Poisson-bracket formulation of the dynamics of fluids of deformable\n  particles: Using the Poisson bracket method, we derive continuum equations for a fluid\nof deformable particles in two dimensions. Particle shape is quantified in\nterms of two continuum fields: an anisotropy density field that captures the\ndeformations of individual particles from regular shapes and a shape tensor\ndensity field that quantifies both particle elongation and nematic alignment of\nelongated shapes. We explicitly consider the example of a dense biological\ntissue as described by the Vertex model energy, where cell shape has been\nproposed as a structural order parameter for a liquid-solid transition. The\nhydrodynamic model of biological tissue proposed here captures the coupling of\ncell shape to flow, and provides a starting point for modeling the rheology of\ndense tissue.",
        "positive": "Ion distribution around a charged rod in one and two component solvents:\n  Preferential solvation and first order ionization phase transition: In one and two component solvents, we calculate the counterion distribution\naround a charged rod treating the degree of ionization $\\alpha$ as an annealed\nvariable dependent on its local environment. In the one component case,\n$\\alpha$ is determined under various conditions without and with salt. In the\ntwo component case, we take into account the preferential solvation of the\ncounterions and the ionized monomers and the short-range interaction between\nthe rod and the solvent without salt. It then follows a composition-dependent\nmass action law. Mesoscopic variations of the composition and the counterions\nare produced around a chraged rod, which sensitively depend on various\nparameters of the molecular interactions.\n  Furthermore, we predict a first order phase transition of weak-to-strong\ndissociation for strong preferential solvation. It can occur in expanded states\nof a polymer chain. This transition line starts from a point on the solvent\ncoexistence curve and ends at a critical point in the plane of the temperature\nand the solvent composition. The composition change around a charged rod is\nlong-ranged near the solvent critical point."
    },
    {
        "anchor": "Beyond power-law density scaling: Theory, Simulation, and Experiment: Supercooled liquids are characterized by relaxation times that increase\ndramatically by cooling or compression. Many liquids have been shown to obey\npower-law density scaling, according to which the relaxation time is a function\nof density to some power over temperature. We show that power-law density\nscaling breaks down for larger density variations than usually studied. This is\ndemonstrated by simulations of the Kob-Andersen binary Lennard-Jones mixture\nand two molecular models, as well as by experimental results for two van der\nWaals liquids. A more general form of density scaling is derived, which is\nconsistent with results for all the systems studied. An analytical expression\nfor the scaling function for liquids of particles interacting via generalized\nLennard-Jones potentials is derived and shown to agree very well with\nsimulations. This effectively reduces the problem of understanding the viscous\nslowing down from being a quest for a function of two variables to a search for\na single-variable function.",
        "positive": "Exact versus mean-field description of the Bose-Einstein condensate: a\n  model study: We study a system of trapped bosonic particles interacting by model harmonic\nforces. Our model allows for detailed examination of the notion of an order\nparameter (a condensate wave function). By decomposing a single particle\ndensity matrix into coherent eigenmodes we study an effect of interaction on\nthe condensate. We show that sufficiently strong interactions cause that the\ncondensate disappears even if the whole system is in its lowest energy state.\nIn the second part of our paper we discuss the validity of the Bogoliubov\napproximation by comparing its predictions with results inferred from the\nexactl y soluble model. In particular we examine an energy spectrum,\noccupation, and fluctuations of the condensate. We conclude that Bogoliubov\napproach gives quite accurate description of the system in the limit of weak\ninteractions."
    },
    {
        "anchor": "Kinetics of Surfactant Adsorption at Fluid/Fluid Interfaces: Non-ionic\n  Surfactants: We present a model treating the kinetics of adsorption of soluble\nsurface-active molecules at the interface between an aqueous solution and\nanother fluid phase. The model accounts for both the diffusive transport inside\nthe solution and the kinetics taking place at the interface using a free-energy\nformulation. In addition, it offers a general method of calculating dynamic\nsurface tensions. Non-ionic surfactants are shown, in general, to undergo a\ndiffusion-limited adsorption, in accord with experimental findings.",
        "positive": "Immersed boundary method for dynamic simulation of polarizable colloids\n  of arbitrary shape in explicit ion electrolytes: We develop a computational method for modeling electrostatic interactions of\narbitrarily-shaped, polarizable objects on colloidal length scales, including\ncolloids/nanoparticles, polymers, and surfactants, dispersed in explicit ion\nelectrolytes and nonionic solvents. Our method computes the nonuniform\npolarization charge distribution induced in a colloidal particle by both\nexternally applied electric fields and local electric fields arising from other\ncharged objects in the dispersion. This leads to expressions for electrostatic\nenergies, forces, and torques that enable efficient molecular dynamics and\nBrownian dynamics simulations of colloidal dispersions in electrolytes, which\ncan be harnessed to accurately predict structural and transport properties. We\ndescribe an implementation in which colloidal particles are modeled as rigid\ncomposites of small spherical beads that tessellate the surface of the\nparticle. The electrostatics calculations are accelerated using a\nspectrally-accurate particle-mesh-Ewald technique implemented on a graphics\nprocessing unit (GPU) and regularized such that the electrostatic calculations\nare well-defined even for overlapping bodies. We demonstrate the effectiveness\nof this approach through a series of calculations, including the induced dipole\nmoments and forces for one, two, and lattices of spherical colloids in an\nelectric field; the induced dipole moment and torque for anisotropic particles\nin an electric field; the equilibrium distribution of ions in the double layer\naround charged colloids; the dynamics of charged colloids; and ions in the\ndouble layer around a polarizable colloid exposed to an electric field."
    },
    {
        "anchor": "Influence of inherent structure shear stress of supercooled liquids on\n  their shear moduli: Configurations of supercooled liquids residing in their local potential\nminimum (i.e. in their inherent structure, IS) were found to support a non-zero\nshear stress. This IS stress was attributed to the constraint to the energy\nminimization imposed by boundary conditions, which keep size and shape of the\nsimulation cell fixed. In this paper we further investigate the influence of\nthese boundary conditions on the IS stress. We investigate its importance for\nthe computation of the low frequency shear modulus of a glass obtaining a\nconsistent picture for the low- and high frequency shear moduli over the full\ntemperature range. Hence, we find that the IS stress corresponds to a\nnon-thermal contribution to the fluctuation term in the Born-Green expression.\nThis leads to an unphysical divergence of the moduli in the low temperature\nlimit if no proper correction for this term is applied. Furthermore, we clarify\nthe IS stress dependence on the system size and put its origin on a more formal\nbasis.",
        "positive": "Quantum spins mixing in spinor Bose-Einstein condensates: We examine the internal structure of the ground states of a trapped\nBose-Einstein condensate in which atoms have three internal hyperfine spins. We\ndetermine a set of collective spin states which minimize the interaction energy\nbetween condensate atoms. We also examine the internal dynamics of an initially\nspin polarized condensate. The time scale of spin-mixing is predicted."
    },
    {
        "anchor": "Polymers in Swarming Bacterial Turbulence: We experimentally investigate the effects of polymer additives on the\ncollective dynamics of swarming Serratia marcescens in quasi two-dimensional\n(2D) liquid films. We find that even minute amounts of polymers (< 20 ppm) can\nsignificantly enhance swimming speed and promote largescale coherent\nstructures. Velocity statistics show that polymers suppress large velocity\nfluctuation, transforming the velocity distributions from super-Gaussian to\nGaussian. Spatial and temporal correlation functions suggest that polymers\nincrease both the size and lifetime of flow structures. The energy spectra show\nan exponential decay at low wavenumbers, with a characteristic length scale\nincreasing with polymer concentration. Overall, these result show polymers can\nmediate bacteria interaction and promote large-scale coherence in dense active\nsuspensions.",
        "positive": "Derivation of Hydrodynamics for Multi-Relaxation Time Lattice Boltzmann\n  using the Moment-Approach: A general analysis of the hydrodynamic limit of multi-relaxation time lattice\nBoltzmann models is presented. We examine multi-relaxation time BGK collision\noperators that are constructed similarly to those for the MRT case, however,\nwithout explicitly moving into a moment space representation. The corresponding\n'moments' are derived as left eigenvectors of said collision operator in\nvelocity space. Consequently we can, in a representation independent of the\nchosen base velocity set, generate the conservation equations. We find a\nsignificant degree of freedom in the choice of the collision matrix and the\nassociated basis which leaves the collision operator invariant. Therefore we\ncan explain why MRT implementations in the literature reproduce identical\nhydrodynamics despite being based on different orthogonalization relations."
    },
    {
        "anchor": "Dynamic Stern layers in charge-regulating electrokinetic systems: three\n  regimes from an analytical approach: We present analytical solutions for the electrokinetics at a charged surface\nwith both non-zero Stern-layer conductance and finite chemical reaction rates.\nWe have recently studied the same system numerically [Werkhoven {\\em et al.},\nPhys. Rev. Lett. {\\bf 120}, 264502 (2018)], and have shown that an applied\npressure drop across the surface leads to a non-trivial, laterally\nheterogeneous surface charge distribution at steady state. In this work, we\nlinearise the governing electrokinetic equations to find closed expressions for\nthe surface charge profile and the generated streaming electric field. The main\nresults of our calculations are the identification of three important length\nand time scales that govern the charge distribution, and consequently the\nclassification of electrokinetic systems into three distinct regimes. The three\ngoverning time scales can be associated to (i) the chemical reaction, (ii)\ndiffusion in the Stern layer, and (iii) conduction in the Stern layer, where\nthe dominating (smallest) time scale characterises the regime. In the\nreaction-dominated regime we find a constant surface charge with an edge\neffect, and recover the Helmholtz-Smoluchowski equation. In the other two\nregimes, we find that the surface charge heterogeneity extends over the entire\nsurface, either linearly (diffusion-dominated regime) or nonlinearly\n(conduction-dominated regime).",
        "positive": "Yakhot's model of strong turbulence: A generalization of scaling models\n  of turbulence: We report on some implications of the theory of turbulence developed by V.\nYakhot [V. Yakhot, Phys. Rev. E {\\bf 57}(2) (1998)]. In particular we focus on\nthe expression for the scaling exponents $\\zeta_{n}$. We show that Yakhot's\nresult contains three well known scaling models as special cases, namely K41,\nK62 and the theory by V. L'vov and I. Procaccia [V. L'vov & I. Procaccia, Phys.\nRev. E {\\bf 62}(6) (2000)]. The model furthermore yields a theoretical\njustification for the method of extended self--similarity (ESS)."
    },
    {
        "anchor": "Slow dynamics near glass transitions in thin polymer films: The $\\alpha$-process (segmental motion) of thin polystyrene films supported\non glass substrate has been investigated in a wider frequency range from\n10$^{-3}$ Hz to 10$^4$ Hz using dielectric relaxation spectroscopy and thermal\nexpansion spectroscopy. The relaxation rate of the $\\alpha$-process increases\nwith decreasing film thickness at a given temperature above the glass\ntransition. This increase in the relaxation rate with decreasing film thickness\nis much more enhanced near the glass transition temperature. The glass\ntransition temperature determined as the temperature at which the relaxation\ntime of the $\\alpha$-process becomes a macroscopic time scale shows a distinct\nmolecular weight dependence. It is also found that the Vogel temperature has\nthe thickness dependence, i.e., the Vogel temperature decreases with decreasing\nfilm thickness. The expansion coefficient of the free volume $\\alpha_f$ is\nextracted from the temperature dependence of the relaxation time within the\nfree volume theory. The fragility index $m$ is also evaluated as a function of\nthickness. Both $\\alpha_f$ and $m$ are found to decrease with decreasing film\nthickness.",
        "positive": "Lattice Monte Carlo Simulations of Polymer Melts: We use Monte Carlo simulations to study polymer melts consisting of fully\nflexible and moderately stiff chains in the bond fluctuation model at a volume\nfraction $0.5$. In order to reduce the local density fluctuations, we test a\npre-packing process for the preparation of the initial configurations of the\npolymer melts, before the excluded volume interaction is switched on\ncompletely. This process leads to a significantly faster decrease of the number\nof overlapping monomers on the lattice. This is useful for simulating very\nlarge systems, where the statistical properties of the model with a marginally\nincomplete elimination of excluded volume violations are the same as those of\nthe model with strictly excluded volume. We find that the internal mean square\nend-to-end distance for moderately stiff chains in a melt can be very well\ndescribed by a freely rotating chain model with a precise estimate of the\nbond-bond orientational correlation between two successive bond vectors in\nequilibrium. The plot of the probability distributions of the reduced\nend-to-end distance of chains of different stiffness also shows that the data\ncollapse is excellent and described very well by the Gaussian distribution for\nideal chains. However, while our results confirm the systematic deviations\nbetween Gaussian statistics for the chain structure factor $S_c(q)$ [minimum in\nthe Kratky-plot] found by Wittmer et al.~\\{EPL {\\bf 77} 56003 (2007).\\} for\nfully flexible chains in a melt, we show that for the available chain length\nthese deviations are no longer visible, when the chain stiffness is included.\nThe mean square bond length and the compressibility estimated from collective\nstructure factors depend slightly on the stiffness of the chains."
    },
    {
        "anchor": "Mixed scenario of the charged helium surface reconstruction: Discussed in the paper is the mixed scenario of charged liquid surface\nreconstruction when the surface 2D charge density is close to the saturation.\nThe basic building block of arising honeycomb structure is shown to be a\nmodified multielectron dimple.",
        "positive": "Amorphous and ordered states of concentrated hard spheres under\n  oscillatory shear: Hard sphere colloidal particles are a basic model system for general research\ninto phase behavior, ordering and out-equilibrium glass transitions.\nExperimentally it has been shown that oscillatory shearing of a monodisperse\nhard sphere glass, produces two different crystal orientations; a Face Centered\nCubic (FCC) crystal with the close packed direction parallel to shear at high\nstrains and an FCC crystal with the close packed direction perpendicular to\nshear at low strains. Here, using Brownian dynamics simulations of hard sphere\nparticles, we have examined high volume fraction shear-induced crystals under\noscillatory shear as well as the same volume fraction glass counterparts. We\nfind that, while the displacements under shear of the glass are isotropic, the\nsheared FCC crystal structures oriented parallel to shear, are anisotropic due\nto the cooperative motion of velocity-vorticity layers of particles sliding\nover each other. These sliding layers generally result in lower stresses and\nless overall particle displacements. Additionally, from the two crystal types,\nthe perpendicular crystal exhibits less stresses and displacements at smaller\nstrains, however at larger strains, the sliding layers of the parallel crystal\nare found to be more efficient in minimizing stresses and displacements, while\nthe perpendicular crystal becomes unstable. The findings of this work suggest\nthat the process of shear-induced ordering for a colloidal glass is facilitated\nby large out of cage displacements, which allow the system to explore the\nenergy landscape and find the minima in energy, stresses and displacements by\nconfiguring particles into a crystal oriented parallel to shear."
    },
    {
        "anchor": "Titration in Canonical and Grand-Canonical Ensembles: We discuss problems associated with the notion of pH in heterogeneous\nsystems. For homogeneous systems, standardization protocols lead to a well\ndefined quantity, which although different from S\\o rensen's original idea of\npH, is well reproducible and has become accepted as the measure of the\n``hydrogen potential\". On the other hand, for heterogeneous systems, pH defined\nin terms of the chemical part of the electrochemical activity is\nthermodynamically inconsistent and runs afoul of the Gibbs-Guggenheim principle\nthat forbids splitting of the electrochemical potential into separate chemical\nand electrostatic parts -- since only the sum of two has any thermodynamic\nmeaning. The problem is particularly relevant for modern simulation methods\nwhich involve charge regulation of proteins, polyelectrolytes, nanoparticles,\ncolloidal suspensions etc. In this paper we show that titration isotherms\ncalculated using semi-grand canonical simulations can be very different from\nthe ones obtained using canonical reactive Monte Carlo simulations.",
        "positive": "Solvation force between tethered polyelectrolyte layers. A density\n  functional approach: We use a version of the density functional theory to study the solvation\nforce between two plates modified with a tethered layer of chains. The chains\nare built of tangentially jointed charged spherical segments. The plates are\nimmersed in an electrolyte solution that involves cations, anions and solvent\nmolecules. The latter molecules are modelled as hard spheres. We study the\ndependence of the solvation force and the structure of chains and of solute\nmolecules on the grafting density, length of chains, architecture of the chains\nand on concentration of the solute."
    },
    {
        "anchor": "Shear and longitudinal viscosity of non-ionic C12E8 aqueous solutions: We present measurements of the steady shear viscosity, the longitudinal\nelastic modulus and the ultrasonic absorption in the one-phase isotropic liquid\nregion of the nonionic surfactant C12E8 aqueous solutions. The overall results\nsupport the presence of two separated intervals of concentration corresponding\nto different structural properties. In the surfactant-rich region the\ntemperature dependence of the steady shear viscosity follows an equation\ncharacteristic of glass-like systems. The ultrasonic absorption spectra show\nunambiguous evidence of viscoelastic behaviour described by a Cole-Cole\nrelaxation formula. In the water-rich region the behaviour of the measured\nquantities are more complex and reflect the presence of dispersed aggregates\nwhose size increases with temperature and concentration. An additional low\nfrequency contribution is also observed, which is ascribed to the exchange of\nwater molecules and/or surfactant monomers between the aggregates and the bulk\nsolvent region.",
        "positive": "Growth of equilibrium structures built from a large number of distinct\n  component types: We use simple analytic arguments and lattice-based computer simulations to\nstudy the growth of structures made from a large number of distinct component\ntypes. Components possess 'designed' interactions, chosen to stabilize an\nequilibrium target structure in which each component type has a defined spatial\nposition, and 'undesigned' interactions that allow components to bind in a\ncompositionally-disordered way. We find that high-fidelity growth of the\nequilibrium target structure can happen in the presence of substantial\nattractive undesigned interactions, as long as the energy scale of the set of\ndesigned interactions is chosen appropriately. This observation may help\nexplain why equilibrium DNA 'brick' structures self-assemble even if undesigned\ninteractions are not suppressed [Ke et al. Science 338, 1177 (2012)]. We also\nfind that high-fidelity growth of the target structure is most probable when\ndesigned interactions are drawn from a distribution that is as narrow as\npossible. We use this result to suggest how to choose complementary DNA\nsequences in order to maximize the fidelity of multicomponent self-assembly\nmediated by complementary DNA interactions. We also comment on the prospect of\ngrowing macroscopic structures in this manner"
    },
    {
        "anchor": "Cyclization of Short DNA Fragments: From the per unit length free energy for DNA under tension, we have\ncalculated an effective contour length dependent persistence length for short\nDNA. This effective persistence length results from the enhanced fluctuations\nin short DNA. It decreases for shorter DNA, making shorter DNA more flexible.\nThe results of the J-factor calculated using this effective persistence length\nare in good agreement with experimental data.",
        "positive": "Finite-amplitude inhomogeneous plane waves of exponential type in\n  incompressible elastic materials: It is proved that elliptically-polarized finite-amplitude inhomogeneous plane\nwaves may not propagate in an isotropic elastic material subject to the\nconstraint of incompressibility. The waves considered are harmonic in time and\nexponentially attenuated in a direction distinct from the direction of\npropagation. The result holds whether the material is stress-free or\nhomogeneously deformed."
    },
    {
        "anchor": "A Simple Incremental Modelling of Granular-Media Mechanics: It is proposed a simple non linear incremental modelling of the axi-symmetric\ncompression of granular materials and powders. It describes the main features\nof undrained compression and of oedometric compression using the results of\ncompression tests at constant lateral stress . It generalises the concept of\ncharacteristic state. It shows that trajectories arriving at a given critical\nstate shall pertain to a single surface in the (v,q,p) space, which confirms\nthe recent result demonstrating that Hvorslev's and Roscoe's surfaces are part\nof the same surface. Effects of induced anisotropy are discussed; comparison\nwith classical camclay model is performed.",
        "positive": "The role of shear in crystallization kinetics: From suppression to\n  enhancement: In many technical applications, but also in natural processes like ice\nnucleation in clouds, crystallization proceeds in the presence of stresses and\nflows, hence the importance to understand the crystallization mechanism in\nsimple situations. We employ molecular dynamics simulations to study the\ncrystallization kinetics of a nearly hard sphere liquid that is weakly sheared.\nWe demonstrate that shear flow both enhances and suppresses the crystallization\nkinetics of hard spheres. The effect of shear depends on the quiescent\nmechanism: suppression in the activated regime and enhancement in the\ndiffusion-limited regime for small strain rates. At higher strain rates\ncrystallization again becomes an activated process even at densities close to\nthe glass transition."
    },
    {
        "anchor": "Elasticity and thermal transport of commodity plastics: Applications of commodity polymers are often hindered by their low thermal\nconductivity. In these systems, going from the standard polymers dictated by\nweak van der Waals interactions to biocompatible hydrogen bonded smart\npolymers, the thermal transport coefficient k varies between 0.1 - 0.4 W/Km.\nCombining all-atom molecular dynamics simulations with some experiments, we\nstudy thermal transport and its link to the elastic response of commodity\nplastics. We find that there exists a maximum attainable stiffness (or sound\nwave velocity), thus providing an upper bound of k for these solid polymers.\nThe specific chemical structure and the glass transition temperature play no\nrole in controlling k, especially when the microscopic interactions are\nhydrogen bonding based. Our results are consistent with the minimum thermal\nconductivity model and existing experiments. The effect of polymer stretching\non k is also discussed.",
        "positive": "Directed Self-Assembly of Quantum Dots in a Nematic Liquid Crystal: Self organizing anisotropic nematic liquid crystals (LCs) induce\nself-assembly on quantum dots (QDs) to form one-dimensional chains along the\nnematic director. Spatial ordering of QDs, achieved in the nematic LC matrix,\ncan be controlled in a preferred direction on application of electric fields,\ngaining better self-assembly. Once the field goes off, the LC+QD system relaxes\nback to the original state, revealing the intrinsic dynamics. Due to the\ndielectric anisotropy of the system, this dynamic response can be captured by\nstudying dielectric relaxation. The studied dynamic response reveals insights\non the field-induced self-assembly mechanism and the stability of the LC+QD\nsystem."
    },
    {
        "anchor": "Capillary-driven biaxial planar and homeotropic nematization of hard\n  cylinders: We use the Parsons Lee modification of Onsagers second virial theory within\nthe restricted orientation approximation to analyse the phase behaviour of hard\ncylindrical rods confined in narrow pores Depending on the wall to wall\nseparation we predict a number of distinctly different surface generated\nnematic phases including a biaxial planar nematic with variable number of\nlayers a monolayer homeotropic and a hybrid T type structure For narrow pores\nwe find evidence of two types of second order uniaxial biaxial transitions\ndepending on the aspect ratio of the particles More specifically we observe a\ncontinuous cross over from n to layers each with a distinct planar anchoring\nsymmetry as well as first order transitions from planar to homeotropic surface\nanchoring Contrary to the previously studied case of parallelepipeds we find\nthat the surface anchoring transition from planar to homeotropic symmetry\noccurs at much lower overall rod packing fractions",
        "positive": "Effect of Salt Concentration on Dielectric Properties of Li-Ion\n  Conducting Blend Polymer Electrolytes: In the present article, we have studied the effect of the salt concentration\n(LiPF6) on transport properties and ion dynamics of blend solid polymer\nelectrolyte (PEO PAN) prepared by solution cast technique. Fourier transform\ninfrared (FTIR) spectroscopy confirms the presence of microscopic interactions\nsuch as polymer ion and ion ion interaction evidenced by a change in peak area\nof anion stretching mode. The fraction of free anions and ion pairs obtained\nfrom the analysis of FTIR implies that both influence the ionic conductivity\nwith different salt concentration. The complex dielectric permittivity,\ndielectric loss, complex conductivity have been analyzed and fitted in the\nentire frequency range (1 Hz to 1 MHz) at room temperature. The addition of\nsalt augments the dielectric constant and shift of relaxation peak in loss\ntangent plot toward high frequency indicates a decrease of relaxation time. We\nhave implemented the Sigma representation sigma double prime vs sigma prime for\nsolid lithium ion conducting films which provide better insight toward\nunderstating of the dispersion region in Cole Cole plot epsilon double prime vs\nepsilon prime in lower frequency window. The dielectric strength, relaxation\ntime and hopping frequency are in correlation with the conductivity which\nreveals the authenticity of results. Finally, the ion transport mechanism was\nproposed for getting the better understanding of the ion migration in the\npolymer matrix."
    },
    {
        "anchor": "Reaction-driven Diffusiophoresis of Liquid Condensates: Mechanisms for\n  Intra-cellular Organization: The cellular environment, characterized by its intricate composition and\nspatial organization, hosts a variety of organelles, ranging from\nmembrane-bound ones to membraneless structures that are formed through\nliquid-liquid phase separation. Cells show precise control over the position of\nsuch condensates. We demonstrate that organelle movement in external\nconcentration gradients, diffusiophoresis, is distinct from the one of colloids\nbecause fluxes can remain finite inside the liquid-phase droplets and movement\nof the latter arises from incompressibility. Within cellular domains\ndiffusiophoresis naturally arises from biochemical reactions that are driven by\na chemical fuel and produce waste. Simulations and analytical arguments within\na minimal model of reaction-driven phase separation reveal that the directed\nmovement stems from two contributions: Fuel and waste are refilled or extracted\nlocally, resulting in concentration gradients, which (i) induce product fluxes\nvia incompressibility and (ii) result in an asymmetric forward reaction in the\ndroplet's surroundings (as well as asymmetric backward reaction inside the\ndroplet), thereby shifting the droplet's position. We show that the former\ncontribution dominates and sets the direction of the movement, away from or\ntowards fuel source and waste sink, depending on the product molecules'\naffinity towards fuel and waste, respectively. The mechanism thus provides a\nsimple means to organize condensates with different composition. Particle-based\nsimulations and systems with more complex reaction cycles corroborate the\nrobustness and universality of this mechanism.",
        "positive": "Error-proof programmable self-assembly of DNA-nanoparticle clusters: We study theoretically a new generic scheme of programmable self-assembly of\nnanoparticles into clusters of desired geometry. The problem is motivated by\nthe feasibility of highly selective DNA-mediated interactions between colloidal\nparticles. By analyzing both a simple generic model and a more realistic\ndescription of a DNA-colloidal system, we demonstrate that it is possible to\nsuppress the glassy behavior of the system, and to make the self-assembly\nnearly error-proof. This regime requires a combination of stretchable\ninterparticle linkers (e.g. sufficiently long DNA), and a soft repulsive\npotential. The jamming phase diagram and the error probability are computed for\nseveral types of clusters. The prospects for the experimental implementation of\nour scheme are also discussed. PACS numbers: 81.16.Dn, 87.14.Gg, 36.40.Ei"
    },
    {
        "anchor": "The effect of impurities on the mobility of single crystal pentacene: We have obtained a hole mobility for the organic conductor pentacene of 35\ncm2/Vs at room temperature increasing to 58 cm2/Vs at 225K. These high\nmobilities result from a purification process in which 6,13-pentacenequinone\nwas removed by vacuum sublimation. The number of traps is reduced by two orders\nof magnitude compared with conventional methods. The temperature depandence of\nthe mobility is consistent with the band model for electronic transport.",
        "positive": "Thermodynamic relations among isotropic material properties in\n  conditions of plane shear stress: We present new general relationships among the material properties of an\nisotropic material kept in homogeneous stress conditions with hydrostatic\npressure and plane shear. The derivation is not limited to the proximity of the\nzero shear-stress and -strain condition, which allows us to identify the\nrelationship between adiabatic and isothermal shear compliances (inverse of the\nmoduli of rigidity) along with new links, among others, between isobaric and\nisochoric shear thermal expansion coefficients, heat capacities at constant\nstress and constant shear strain. Such relationships are important for a\nvariety of applications, including characterization of nanomaterials as well as\nidentification of properties related to earthquakes precursors and complex\nmedia (e.g., soil) behaviors. The results may be useful to investigate the\nbehavior of materials during phase transitions involving shear or in\nnon-homogeneous conditions within a local thermodynamic equilibrium framework."
    },
    {
        "anchor": "Solution of the Percus-Yevick equation for hard discs: We solve the Percus-Yevick equation in two dimensions by reducing it to a set\nof simple integral equations. We numerically obtain both the pair correlation\nfunction and the equation of state for a hard disc fluid and find good\nagreement with available Monte-Carlo calculations. The present method of\nresolution may be generalized to any even dimension.",
        "positive": "Arrested coalescence of viscoelastic droplets: Triplet shape and\n  restructuring: The stability of shapes formed by three viscoelastic droplets during their\narrested coalescence has been investigated using micromanipulation experiments.\nAddition of a third droplet to arrested droplet doublets is shown to be\ncontrolled by the balance between interfacial pressures driving coalescence and\ninternal elasticity that resists total consolidation. The free fluid available\nwithin the droplets controls the transmission of stress during droplet\ncombination and allows connections to occur via formation of a neck between the\ndroplets. The anisotropy of three-droplet systems adds complexity to the\nsymmetric case of two-droplet aggregates because of the multiplicity of\norientations possible for the third droplet. When elasticity dominates, the\ninitial orientation of the third droplet is preserved in the triplet's final\nshape. When elasticity is dominated by the interfacial driving force, the final\nshape can deviate strongly from the initial positioning of droplets. Movement\nof the third droplet to a more compact packing occurs, driven by liquid\nmeniscus expansion that minimizes the surface energy of the triplet. A range of\ncompositions and orientations are examined and the resulting domains of\nrestructuring and stability are mapped based on the final triplet structure. A\ngeometric and a physical model are used to explain the mechanism driving\nmeniscus-induced restructuring and are related to the impact of these phenomena\non multiple droplet emulsions."
    },
    {
        "anchor": "Equation of state of surface-adsorbing colloids: We have developed a simulation model to describe particle adsorption to and\ndesorption from liquid interfaces. Using this model we formulate a closed\ninterfacial equation of state for repulsive elastic spheres. The effect of a\nlong-range attractive interaction is introduced by perturbation theory, and the\neffect a short-range attraction is studied using direct simulation. Based on\nour model predictions we conclude that for polymeric particles the surface\npressure cannot be modelled directly by inert particles that interact via some\neffective potential. Internal degrees of freedom within gel particles are\nall-important. Consequently, the surface pressure of a fully packed layer is\nnot proportional to kT/d^2, where d is the particle diameter; but proportional\nto kT/dm^2, where dm is the size of the molecular units that make up the\nparticle. This increases the surface pressure and modulus by some four orders\nof magnitude. For short range interaction we study the dynamic behaviour, and\nfind fractal-like structures at low concentrations. At intermediate coverage an\nirregular structure is formed that resembles a spinodal system. This system\nfreezes, which arrests the spinodal structure. At high surface coverage the\nsimulations show poly-crystalline domains. For dilute systems, the strength of\nthe surface layers is determined by simulated compression and expansion. We\nfind a power law for the surface pressure (Pi ~ Gamma^10+/-0.5), which is\nrelated to the (fractal) structure of the adsorbed network. The power law is\nconsistent with surface percolation.",
        "positive": "Dynamics and density distribution of strongly confined noninteracting\n  nonaligning self-propelled particles in a nonconvex boundary: We study the dynamics of non-aligning, non-interacting self-propelled\nparticles confined to a box in two dimensions. In the strong confinement limit,\nwhen the persistence length of the active particles is much larger than the\nsize of the box, particles stay on the boundary and align with the local\nboundary normal. It is then possible to derive the steady-state density on the\nboundary for arbitrary box shapes. In non-convex boxes, the non-uniqueness of\nthe boundary normal results in hysteretic dynamics and the density is\nnon-local, i.e. it depends on the global geometry of the box. These findings\nestablish a general connection between the geometry of a confining box and the\nbehavior of an ideal active gas it confines, thus providing a powerful tool to\nunderstand and design such confinements."
    },
    {
        "anchor": "The Polyakov line, the Nishimori line and polymer networks standing a\n  smectic liquid crystal: We once more specify an universality of a phase transition from smectic-A to\nnematic phase in the crosslinked polymer network with a smectic liquid crystal,\nbasing on the X-ray and $^1H$-NMR spectroscopy experiments. Comparing the\nsuperconducting 3D XY gauge theory and typical spin-glass models for such\nsystems, it is possible to clarify a type of a phase transition, which might be\nthe reason of percolation.",
        "positive": "Simulation of a two-dimensional model for colloids in a uniaxial\n  electric field: We perform Monte Carlo simulations of a simplified two-dimensional model for\ncolloidal hard spheres in an external uniaxial AC electric field.\nExperimentally, the external field induces dipole moments in the colloidal\nparticles, which in turn form chains. We therefore approximate the system as\ncomposed of well formed chains of dipolar hard spheres of a uniform length. The\ndipolar interaction between colloidal spheres gives rise to an effective\ninteraction between the chains, which we treat as disks in a plane, that\nincludes a short range attraction and long range repulsion. Hence, the system\nfavors finite clustering over bulk phase separation and indeed we observe at\nlow temperature and density that the system does form a cluster phase. As\ndensity increases, percolation is accompanied by a pressure anomaly. The\npercolated phase, despite being composed of connected, locally crystalline\ndomains, does not bear the typical signatures of a hexatic phase. At very low\ndensities, we find no indication of a \"void phase\" with a cellular structure\nseen recently in experiments."
    },
    {
        "anchor": "Influences des param\u00e8tres microm\u00e9caniques dans la simulation\n  num\u00e9rique discr\u00e8te des mat\u00e9riaux granulaires : assemblage,\n  d\u00e9formation quasi-statique, \u00e9coulements: We review the influence of micromechanical parameters on the macroscopic\nmechanical behaviour of granular materials, as numerically simulated in\ndiscrete element approaches, both in quasistatic conditions an din dense flow.\nWe insist in particular on the role of suitably defined dimensionless numbers\napt to provide a classification of rheological regimes of quite general\nvalidity.",
        "positive": "Non-equilibrium dynamics of a confined colloidal bilayer in planar shear\n  flow: Using Brownian dynamics (BD) simulations we investigate the impact of shear\nflow on structural and dynamical properties of a system of charged colloids\nconfined to a narrow slit pore. Our model consists of spherical microions\ninteracting through a Derjaguin-Landau-Verwey-Overbeek (DLVO) and a soft-sphere\npotential. The DLVO parameters were chosen according to a system of moderately\ncharged silica particles (with valence Z$\\sim$35) in a solvent of low ionic\nstrength. At the confinement conditions considered, the colloids form two\nwell-pronounced layers. In the present study we investigate shear-induced\ntransitions of the translational order and dynamics in the layers, including a\ndiscussion of the translational diffusion. In particular, we show that\ndiffusion in the shear-melted state can be described by an analytical model\ninvolving a single shear-driven particle in a harmonic trap. We also explore\nthe emergence of zig-zag motion characterized by spatio-temporal oscillations\nof the particles in the layers in the vorticity direction. Similar behavior has\nbeen recently observed in experiments of much thicker colloidal films."
    },
    {
        "anchor": "Stability and onset of two-dimensional viscous fingering in immiscible\n  fluids: Viscous flows in a quasi-two-dimensional Hele-Shaw geometry can lead to an\ninterfacial instability when one fluid, of viscosity $\\eta_{in}$ displaces\nanother of higher viscosity, $\\eta_{out}$. Recent studies have shown that there\nis a delay in the onset of fingering in miscible fluids as the viscosity ratio,\n$\\eta_{in}/\\eta_{out}$, increases and approaches unity; the interface can\nremain stable even though the displacing liquid is less viscous. This paper\nshows that a delayed onset and stable pattern can occur in immiscible fluids as\nwell. However, there are two significant differences between the two cases.\nFirst, in miscible fluids, stable patterns are obtained whenever\n$\\eta_{in}/\\eta_{out} > 0.33$ while in immiscible fluids, the radius at which\nthe onset of fingering starts, $R_{onset}$, increases steadily until\n$\\eta_{in}/\\eta_{out}=1$. A stable pattern is obtained only when the total size\nof the plate used is smaller than $R_{onset}$. Second, once the delayed\nfingering starts in immiscible fluids, the fingers grow faster than the central\ncircular region. In miscible fluids, there is a regime in which the fingers and\nthe central region grow in proportion to each other. These differences between\nmiscible and immiscible fingering are maintained even when we compare\nimmiscible fluids that have very low interfacial tension with miscible fluids\nthat have negligible diffusion.",
        "positive": "Monolayers of hard rods on planar substrates: I. Equilibrium: The equilibrium properties of hard rod monolayers are investigated in a\nlattice model (where position and orientation of a rod are restricted to\ndiscrete values) as well as in an off--lattice model featuring spherocylinders\nwith continuous positional and orientational degrees of freedom. Both models\nare treated using density functional theory and Monte Carlo simulations. Upon\nincreasing the density of rods in the monolayer, there is a continuous ordering\nof the rods along the monolayer normal (\"standing up\" transition). The\ncontinuous transition also persists in the case of an external potential which\nfavors flat--lying rods in the monolayer. This behavior is found in both the\nlattice and the continuum model. For the lattice model, we find very good\nagreement between the results from the specific DFT used (lattice fundamental\nmeasure theory) and simulations. The properties of lattice fundamental measure\ntheory are further illustrated by the phase diagrams of bulk hard rods in two\nand three dimensions."
    },
    {
        "anchor": "Stress Field at a Sliding Frictional Contact: Experiments and\n  Calculations: A MEMS-based sensing device is used to measure the normal and tangential\nstress fields at the base of a rough elastomer film in contact with a smooth\nglass cylinder in steady sliding. This geometry allows for a direct comparison\nbetween the stress profiles measured along the sliding direction and the\npredictions of an original \\textit{exact} bidimensional model of friction. The\nlatter assumes Amontons' friction law, which implies that in steady sliding the\ninterfacial tangential stress is equal to the normal stress times a\npressure-independent dynamic friction coefficient $\\mu_d$, but makes no further\nassumption on the normal stress field. Discrepancy between the measured and\ncalculated profiles is less than 14% over the range of loads explored.\nComparison with a test model, based on the classical assumption that the normal\nstress field is unchanged upon tangential loading, shows that the exact model\nbetter reproduces the experimental profiles at high loads. However, significant\ndeviations remain that are not accounted for by either calculations. In that\nregard, the relevance of two other assumptions made in the calculations, namely\n(i) the smoothness of the interface and (ii) the pressure-independence of\n$\\mu_d$ is briefly discussed.",
        "positive": "Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid: We study a model Coulomb fluid consisting of dipolar solvent molecules of\nfinite extent generalizing the point-like Dipolar Poisson-Boltzmann model (DPB)\npreviously introduced by Coalson and Duncan (J. Phys. Chem 100, 2612 (1996))\nand Abrashkin et al. (Phys. Rev. Lett. 99, 077801 (2007)). We formulate a\nnonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear\ndielectric response in this model for the case of a single plane geometry. Our\nresults shed light on the relevance of nonlocal vs nonlinear effects in\ncontinuum models of material electrostatics."
    },
    {
        "anchor": "First-principles calculations of Raman vibrational modes in the\n  fingerprint region for connective tissue: Vibrational spectroscopy has been widely employed to unravel\nphysical-chemical properties of biological systems. Due to its high sensitivity\nto monitor real time \"in situ\" changes, Raman spectroscopy has been\nsuccessfully employed, e.g., in biomedicine, metabolomics, and biomedical\nengineering. The grounds of interpretation of Raman spectra in these cases is\nthe isolated macromolecules constituent vibrational assignment. Due to this,\nprobe the anharmonic interactions or the mutual interactions among specific\nmoieties/side chains to name but a few is a challenge. We present a complete\nvibrational modes calculation for connective tissue in the fingerprint region\n($800-1800$ cm$^{-1}$) using first-principles Density Functional Theory. Our\nresults indicated that important spectral features correlated to molecular\ncharacteristics have been ignored within the usual tissue spectral bands\nassignments. In particular, we found that the presence of confined water is the\nmain responsible for the observed spectral complexity. Our calculations\naccounted for the inherent complexity of the spectral features in this region\nand useful spectral markers for biological processes were unambiguously\nidentified.",
        "positive": "Contact Force Mediated Rapid Deposition of Colloidal Microspheres\n  Flowing Over Microstructured Barriers: Deposition of particles while flowing past constrictions is a ubiquitous\nphenomenon observed in diverse systems. Some common examples are jamming of\nsalt crystals near the orifice of saltshakers, clogging of filter systems,\ngridlock in vehicular traffic etc. Our work investigates the deposition events\nof colloidal microspheres flowing over microstructured barriers in microfluidic\ndevices. The interplay of DLVO, contact and hydrodynamic forces in facilitating\nrapid deposition of microspheres is discussed. Noticeably, a decrease in the\nelectrostatic repulsion among microspheres leads to linear chain formations,\nwhereas an increase in roughness results in rapid deposition."
    },
    {
        "anchor": "Dynamical heterogeneity in aging colloidal glasses of Laponite: Glasses behave as solids due to their long relaxation time; however the\norigin of this slow response remains a puzzle. Growing dynamic length scales\ndue to cooperative motion of particles are believed to be central to the\nunderstanding of both the slow dynamics and the emergence of rigidity. Here, we\nprovide experimental evidence of a growing dynamical heterogeneity length scale\nthat increases with increasing waiting time in an aging colloidal glass of\nLaponite. The signature of heterogeneity in the dynamics follows from dynamic\nlight scattering measurements in which we study both the rotational and\ntranslational diffusion of the disk-shaped particles of Laponite in suspension.\nThese measurements are accompanied by simultaneous microrheology and\nmacroscopic rheology experiments. We find that rotational diffusion of\nparticles slows down at a faster rate than their translational motion. Such\ndecoupling of translational and orientational degrees of freedom finds its\norigin in the dynamic heterogeneity since rotation and translation probe\ndifferent length scales in the sample. The macroscopic rheology experiments\nshow that the low frequency shear viscosity increases at a much faster rate\nthan both rotational and translational diffusive relaxation times.",
        "positive": "Modelling hollow thermoplastic syntactic foams under high-strain\n  compressive loading: The mechanical response of syntactic foams comprising hollow thermoplastic\nmicrospheres (HTMs) embedded in a polyurethane matrix were experimentally\nexamined under uniaxial compressive strain. Phenomenological strain energy\nmodels were subsequently developed to capture both the axial stress-strain and\ntransverse strain response of the foams. HTM syntactic foams were found to\nexhibit increased small-strain stiffness with reduced density, revealing a\nhighly tuneable and extremely lightweight syntactic foam blend for\napplications. The foams were also found to become strongly compressible at\nlarge strains and possess a high threshold for plastic deformation, making them\na robust alternative to hollow glass microsphere syntactic foams. The\nnon-standard transverse strain relationship exhibited by HTM syntactic foams at\nhigh filling fractions was captured by Ogden-type strain energy models. The\nthermal characteristics of these syntactic foams were also explored with\nDifferential Scanning Calorimetry testing which showed that HTMs have a\nnegligible impact on the thermal characteristics of the matrix."
    },
    {
        "anchor": "Passive swimming in low Reynolds number flows: The possibility of microscopic swimming by extraction of energy from an\nexternal flow is discussed, focusing on the migration of a simple trimer across\na linear shear flow. The geometric properties of swimming, together with the\npossible generalization to the case of a vesicle, are analyzed.The mechanism of\nenergy extraction from the flow appears to be the generalization to a discrete\nswimmer of the tank-treading regime of a vesicle. The swimmer takes advantage\nof the external flow by both extracting energy for swimming and \"sailing\"\nthrough it. The migration velocity is found to scale linearly in the stroke\namplitude, and not quadratically as in a quiescent fluid. This effect turns out\nto be connected with the non-applicability of the scallop theorem in the\npresence of external flow fields.",
        "positive": "Relationship between Entropy and Diffusion: A statistical mechanical\n  derivation of Rosenfeld expression for a rugged energy landscape: Diffusion-a measure of dynamics, and entropy-a measure of disorder in the\nsystem, are found to be intimately correlated in many systems, and the\ncorrelation is often strongly non-linear. We explore the origin of this complex\ndependence by studying diffusion of a point Brownian particle on a model\npotential energy surface characterized by ruggedness. If we assume that the\nruggedness has a Gaussian distribution then for this model, one can obtain the\nexcess entropy exactly for any dimension. By using the expression for the mean\nfirst passage time (MFPT), we present a statistical mechanical derivation of\nthe well-known and well-tested scaling relation proposed by Rosenfeld between\ndiffusion and excess entropy. In anticipation that Rosenfeld diffusion-entropy\nscaling (RDES) relation may continue to be valid in higher dimensions (where\nthe mean first passage time approach is not available), we carry out an\neffective medium approximation (EMA) based analysis of the effective transition\nrate, and hence of the effective diffusion coefficient. We show that the EMA\nexpression can be used to derive the RDES scaling relation for any dimension\nhigher than unity. However, RDES is shown to break down in the presence of\nspatial correlation among the energy landscape values."
    },
    {
        "anchor": "From creep to flow: Granular materials under cyclic shear: Granular materials such as sand, powders, and grains are omnipresent in daily\nlife, industrial applications, and earth-science [1]. When unperturbed, they\nform stable structures that resemble the ones of other amorphous solids like\nmetallic and colloidal glasses [2]. It is commonly conjectured that all these\namorphous materials show a universal mechanical response when sheared slowly,\ni.e., to have an elastic regime, followed by yielding [3]. Here we use X-ray\ntomography to determine the microscopic dynamics of a cyclically sheared\ngranular system in three dimensions. Independent of the shear amplitude\n$\\Gamma$, the sample shows a cross-over from creep to diffusive dynamics,\nindicating that granular materials have no elastic response and always yield,\nin stark contrast to other glasses. The overlap function [4] reveals that at\nlarge $\\Gamma$ yielding is a simple cross-over phenomenon, while for small\n$\\Gamma$ it shows features of a first order transition with a critical point at\n$\\Gamma\\approx 0.1$ at which one finds a pronounced slowing down and dynamical\nheterogeneity. Our findings are directly related to the surface roughness of\ngranular particles which induces a micro-corrugation to the potential energy\nlandscape, thus creating relaxation channels that are absent in simple glasses.\nThese processes must be understood for reaching an understanding of the complex\nrelaxation dynamics of granular systems.",
        "positive": "The influence of obstacles on collective motion of self-propelled\n  objects: We investigate the influence of obstacles on the collective motion of self\npropelled objects in the framework of the Vicsek model. The obstacles are\narranged in a square lattice and have circular shape. We show that by\nincreasing the radius of the obstacles the collective motion of the self\npropelled object can be altered from super diffusive to diffusive. For\nobstacles with small radius, the system is composed of large clusters moving in\none direction, for larger radius, the system is composed of small clusters\nmoving randomly in different directions."
    },
    {
        "anchor": "On the location of the surface-attached globule phase in collapsing\n  polymers: We investigate the existence and location of the surface phase known as the\n\"Surface-Attached Globule\" (SAG) conjectured previously to exist in lattice\nmodels of three-dimensional polymers when they are attached to a wall that has\na short range potential. The bulk phase, where the attractive intra-polymer\ninteractions are strong enough to cause a collapse of the polymer into a\nliquid-like globule and the wall either has weak attractive or repulsive\ninteractions, is usually denoted Desorbed-Collapsed or DC. Recently this DC\nphase was conjectured to harbour two surface phases separated by a boundary\nwhere the bulk free energy is analytic while the surface free energy is\nsingular. The surface phase for more attractive values of the wall interaction\nis the SAG phase. We discuss more fully the properties of this proposed surface\nphase and provide Monte Carlo evidence for self-avoiding walks up to length 256\nthat this surface phase most likely does exist. Importantly, we discuss\nalternatives for the surface phase boundary. In particular, we conclude that\nthis boundary may lie along the zero wall interaction line and the bulk phase\nboundaries rather than any new phase boundary curve.",
        "positive": "Stabilisation of Emulsions by Trapped Species: We consider an emulsion whose droplets contain a trapped species (insoluble\nin the continuous phase), and study the emulsion's stability against coarsening\nvia Lifshitz-Slyozov dynamics (Ostwald Ripening). Extending an earlier\ntreatment by Kabalnov et al(Colloids and Surfaces, 24,(1987), 19-32), we derive\na general condition on the mean initial droplet volume which ensures stability,\neven when arbitrary polydispersity is present in both size and composition of\nthe initial droplets. We distinguish \"nucleated\" coarsening, which requires\neither fluctuations about the mean field equations or a tail in the initial\ndroplet size distribution, from \"spinodal\" coarsening in which a typical\ndroplet is locally unstable. A weaker condition for stability, previously\nsuggested by Kabalnov et al., is sufficient only to prevent \"spinodal\"\ncoarsening and is best viewed as a condition for metastability. The coarsening\nof unstable emulsions is considered, and shown at long times to resemble that\nof ordinary emulsions (with no trapped species), but with a reduced value of\nthe initial volume fraction of dispersed phase. We discuss the physical\nprinciples relevant to the stability of emulsions with trapped species,\ndescribing how these may be exploited to restabilise partially coarsened\nemulsions and to \"shrink\" previously formed emulsion droplets to form\n\"miniemulsions\"."
    },
    {
        "anchor": "Variations in Structure Explain the Viscometric Behavior of AOT\n  Microemulsions at Low Water/AOT Molar Ratios: The viscosity of AOT/water/decane water-in-oil microemulsions exhibits a\nwell-known maximum as a function of water/AOT molar ratio, which is usually\nattributed to increased attractions among nearly spherical droplets. The\nmaximum can be removed by adding salt or by changing the oil to CCl$_4$.\nSystematic small-angle X-ray scattering (SAXS) measurements have been used to\nmonitor the structure of the microemulsion droplets in the composition regime\nwhere the maximum appears. On increasing the droplet concentration, the\nscattering intensity is found to scale with the inverse of the wavevector, a\nbehavior which is consistent with cylindrical structures. The inverse\nwavevector scaling is not observed when the molar ratio is changed, moving the\nsystem away from the value corresponding to the viscosity maximum. It is also\nnot present in the scattering from systems containing enough added salt to\nessentially eliminate the viscosity maximum. An asymptotic analysis of the SAXS\ndata, complemented by some quantitative modeling, is consistent with\ncylindrical growth of droplets as their concentration is increased. Such\nelongated structures are familiar from related AOT systems in which the sodium\ncounterion has been exchanged for a divalent one. However, the results of this\nstudy suggest that the formation of non-spherical aggregates at low molar\nratios is an intrinsic property of AOT.",
        "positive": "Monte Carlo cluster algorithm for fluid phase transitions in highly\n  size-asymmetrical binary mixtures: Highly size-asymmetrical fluid mixtures arise in a variety of physical\ncontexts, notably in suspensions of colloidal particles to which much smaller\nparticles have been added in the form of polymers or nanoparticles.\nConventional schemes for simulating models of such systems are hamstrung by the\ndifficulty of relaxing the large species in the presence of the small one. Here\nwe describe how the rejection-free geometrical cluster algorithm (GCA) of Liu\nand Luijten [Phys. Rev. Lett 92, 035504 (2004)] can be embedded within a\nrestricted Gibbs ensemble to facilitate efficient and accurate studies of fluid\nphase behavior of highly size-asymmetrical mixtures. After providing a detailed\ndescription of the algorithm, we summarize the bespoke analysis techniques of\nAshton et al. [J. Chem. Phys. 132, 074111 (2010)] that permit accurate\nestimates of coexisting densities and critical-point parameters. We apply our\nmethods to study the liquid--vapor phase diagram of a particular mixture of\nLennard-Jones particles having a 10:1 size ratio. As the reservoir volume\nfraction of small particles is increased in the range 0--5%, the critical\ntemperature decreases by approximately 50%, while the critical density drops by\nsome 30%. These trends imply that in our system, adding small particles\ndecreases the net attraction between large particles, a situation that\ncontrasts with hard-sphere mixtures where an attractive depletion force occurs."
    },
    {
        "anchor": "Coupling of nanoparticle dynamics to polymer center-of-mass motion in\n  semidilute polymer solutions: We investigate the dynamics of nanoparticles in semidilute polymer solutions\nwhen the nanoparticles are comparably sized to the polymer coils using\nexplicit- and implicit-solvent simulation methods. The nanoparticle dynamics\nare subdiffusive on short time scales before transitioning to diffusive motion\non long time scales. The long-time diffusivities scale according to theoretical\npredictions based on full dynamic coupling to the polymer segmental\nrelaxations. In agreement with our recent experiments, however, we observe that\nthe nanoparticle subdiffusive exponents are significantly larger than predicted\nby the coupling theory over a broad range of polymer concentrations. We\nattribute this discrepancy in the subdiffusive regime to the presence of an\nadditional coupling mechanism between the nanoparticle dynamics and the polymer\ncenter-of-mass motion, which differs from the polymer relaxations that control\nthe long-time diffusion. This coupling is retained even in the absence of\nmany-body hydrodynamic interactions when the long-time dynamics of the colloids\nand polymers are matched.",
        "positive": "Ionic effects on the electric field needed to orient dielectric lamellae: We consider the effect of mobile ions on the applied potential needed to\nreorient a lamellar system of two different materials placed between two planar\nelectrodes. The reorientation occurs from a configuration parallel to the\nelectrodes favored by surface interactions to an orientation perpendicular to\nthe electrodes favored by the electric field. The system consists of\nalternating A and B layers with different dielectric constants. The mobile ions\nare assumed to be insoluble in the B layers and hence confined to the A layers.\nWe find that the ions reduce the needed voltage most strongly when they are\nconstrained such that each A lamella is electrically neutral. In this case, a\nmacroscopic separation of charge and its concomitant lowering of free energy,\nis attained only in the perpendicular orientation. When the ions are free to\nmove between different A layers, such that charge neutrality is only required\nglobally, their effect is smaller and depends upon the preferred surface\ninteraction of the two materials. Under some conditions, the addition of ions\ncan actually stabilize the parallel configuration. Our predictions are relevant\nto recent experiments conducted on lamellar phases of diblock copolymer films\nwith ionic selective impurities."
    },
    {
        "anchor": "Swelling induced debonding of thin hydrogel films grafted on silicon\n  substrates: We report on the delamination of thin ($\\approx \\mu$m) hydrogel films grafted\nto silicon substrates under the action of swelling stresses.\nPoly(dimetylacrylamide) (PDMA) films are synthesized by simultaneously\ncross-linking and grafting preformed polymer chains onto the silicon substrate\nusing a thiol-ene reaction. The grafting density at the film/substrate\ninterface is tuned by varying the surface density of reactive thiol-silane\ngroups on the silicon substrate. Delamination of the films from well controlled\nline defects with low adhesion is monitored under a humid water vapor flow\nensuring full saturation of the polymer network. A propagating delamination of\nthe film is observed under the action of differential swelling stresses at the\ndebonding front. A threshold thickness for the onset of this delamination is\nevidenced which is increasing with grafting density while the debonding\nvelocity is also observed to decrease with an increase in grafting density.\nThese observations are discussed within the framework of a nonlinear fracture\nmechanics model which assumes that the driving force for crack propagation is\nthe difference between the swelling state of the bonded and delaminated parts\nof the film. Using this model, the threshold energy for crack initiation was\ndetermined from the measured threshold thickness and discussed in relation to\nthe surface density of reactive thiol groups on the substrate.",
        "positive": "Eshelby-like forces acting on elastic structures: theoretical and\n  experimental proof: The Eshelbian (or configurational) force is the main concept of a celebrated\ntheoretical framework associated with the motion of dislocations and, more in\ngeneral, defects in solids. In a similar vein, in an elastic structure where a\n(smooth and bilateral) constraint can move and release energy, a force driving\nthe configuration is generated, which therefore is called by analogy\n'Eshelby-like' or 'configurational'. This force (generated by a specific\nmovable constraint) is derived both via variational calculus and,\nindependently, through an asymptotic approach. Its action on the elastic\nstructure is counterintuitive, but is fully substantiated and experimentally\nmeasured on a model structure that we have designed, realized and tested. These\nfindings open a totally new perspective in the mechanics of deformable\nmechanisms, with possible broad applications, even at the nanoscale."
    },
    {
        "anchor": "Tug-of-War in a Double-Nanopore System: We simulate a tug-of-war (TOW) scenario for a model double-stranded DNA\nthreading through a double nanopore (DNP) system. The DNA, simultaneously\ncaptured at both pores is subject to two equal and opposite forces $-\\vec{f}_L=\n\\vec{f}_R$ (TOW), where $\\vec{f}_L$ and $\\vec{f}_R$ are the forces applied to\nthe left and the right pore respectively. Even though the net force on the DNA\npolymer $\\Delta \\vec{f}_{LR}=\\vec{f}_L+ \\vec{f}_R=0$, the mean first passage\ntime (MFPT) $\\langle \\tau \\rangle$ depends on the magnitude of the TOW forces $\n\\left | f_L \\right | = \\left |f_R \\right | = f_{LR}$. We qualitatively explain\nthis dependence of $\\langle \\tau \\rangle$ on $f_{LR}$ from the known results\nfor the single-pore translocation of a triblock copolymer. We demonstrate that\nthe time of flight (TOF) of a monomer with index $m$ ($\\langle \\tau_{LR}(m)\n\\rangle$) from one pore to the other exhibits quasi-periodic structure\ncommensurate with the distance between the pores $d_{LR}$. Finally, we study\nthe case $\\Delta \\vec{f}_{LR}=\\vec{f}_L+ \\vec{f}_R \\ne 0$, and qualitatively\nreproduce the experimental result of the dependence of the MFPT on\n$\\Delta\\vec{f}_{LR}$. For a moderate bias, the MFPT for the DNP system for a\nchain length $N$ follows the same scaling ansatz as that of for the single\nnanopore, $\\langle \\tau \\rangle = \\left( AN^{1+\\nu} + \\eta_{pore}N \\right)\n\\left(\\Delta f_{LR}\\right)^{-1}$, where $\\eta_{pore}$ is the pore friction,\nwhich enables us to estimate $\\langle \\tau \\rangle $ for a long chain. Our\nBrownian dynamics simulation studies provide fundamental insights and valuable\ninformation about the details of the translocation speed obtained from $\\langle\n\\tau_{LR}(m) \\rangle$, and accuracy of the translation of the data obtained in\nthe time-domain to units of genomic distances.",
        "positive": "Non-Equilibrium Fluidization of Dense Active Suspension: We investigate dense suspensions of swimming bacteria prepared in a\nnutrient-exchange chamber. Near the pellet concentration, nonthermal\nfluctuations showed notable agreement between self and collective behaviors, a\nphenomenon not previously observed at equilibrium. The viscosity of active\nsuspensions dramatically decreased compared to their inactive counterparts,\nwhere glassy features, such as non-Newtonian viscosity and dynamic\nheterogeneity, disappeared. Instead, the complex shear modulus showed a\npower-law rheology,$G^*(\\omega)\\propto\\left(-i\\omega\\right)^\\frac{1}{2}$,\nindicating the role of bacterial activity in driving the system towards a\ncritical jamming state."
    },
    {
        "anchor": "A channel Brownian pump powered by an unbiased external force: A Brownian pump of particles in an asymmetric finite tube is investigated in\nthe presence of an unbiased external force. The pumping system is bounded by\ntwo particle reservoirs. It is found that the particles can be pumped through\nthe tube from a reservoir at low concentration to one at the same or higher\nconcentration. There exists an optimized value of temperature (or the amplitude\nof the external force) at which the pumping capacity takes its maximum value.\nThe pumping capacity decreases with increasing the radius at the bottleneck of\nthe tube.",
        "positive": "Scaling of fluctuations in a colloidal glass: We report experimental measurements of particle dynamics in a colloidal glass\nin order to understand the dynamical heterogeneities associated with the\ncooperative motion of the particles in the glassy regime. We study the local\nand global fluctuation of correlation and response functions in an aging\ncolloidal glass. The observables display universal scaling behavior following a\nmodified power-law, with a plateau dominating the less heterogeneous short-time\nregime and a power-law tail dominating the highly heterogeneous long-time\nregime."
    },
    {
        "anchor": "Giant Vesicles with Encapsulated Magnetic Nanowires as Versatile\n  Carriers, Transported via Rotating and Non-Homogeneous Magnetic Fields: In this work, two real-time methods to transport magnetic nanowires confined\nin giant hybrid vesi-cles upon the application of different strategies are\nstudied. The microscale carriers are either mag-netically guided through the\nviscous medium by a non-homogenous field or advected by precisely monitored\nhydrodynamic flows. The slender geometry of the magnetic component enables the\nap-plication of large torques, the in-situ characterization of the rotational\ndynamics, as well as the guided propulsion via the continuous thrust of the\nnanowire tip on the confining bilayer. The flexi-bility of the vesicles,\nrequired to deform along the steering direction during passage through\nmi-croscale openings, is enhanced via the adsorption of non-ionic surfactants\non the lipid membrane. The resulting integrated system is an excellent\ncandidate to transport colloidal cargos or flu-id amounts of some picoliters in\nmicrofluidic platforms, even in physiological environments, since it combines\nthe maneuverability of propelled microscopic systems and the protection\nconferred by the vesicle.",
        "positive": "Intermediate asymptotics on dynamical impact of solid sphere on\n  mili-textured surface: Complex phenomena incorporating several physical properties are abundant\nwhile they are occasionally revealing the variation of power-law behavior\ndepending on the scale. In this present work, the global scaling-behavior of\ndynamical impact of solid sphere onto elastic surface is described. Its\nfundamental dimensionless function was successfully obtained by applying the\ndimensional analysis combined with the solution by energy conservation\ncomplementally. It demonstrates that its power-law behavior is given by the\ncompetition between two power-law relations representing inertial and elastic\nproperty respectively which is strengthened by scale size of sphere. These\nfactors are successfully summarized by the newly defined dimensionless\nparameters which gives two intermediate asymptotics in different scale range.\nThese power-law behaviors given by the theoretical model were compared with\nexperimental results, showing good agreement. This study supplies the insights\nto dimensional analysis and self-similarity in general."
    },
    {
        "anchor": "Collective Motion of Vibrated Polar Disks: We experimentally study a monolayer of vibrated disks with a built-in polar\nasymmetry which enables them to move quasi-balistically on a large persistence\nlength. Alignment occurs during collisions as a result of self-propulsion and\nhard core repulsion. Varying the amplitude of the vibration, we observe the\nonset of large-scale collective motion and the existence of giant number\nfluctuations with a scaling exponent in agreement with the predicted\ntheoretical value.",
        "positive": "The Role of Stickiness in the Rheology of Semiflexible Polymers: Semiflexible polymers form central structures in biological material.\nModeling approaches usually neglect influences of polymer-specific molecular\nfeatures aiming to describe semiflexible polymers universally. Here, we\ninvestigate the influence of molecular details on networks assembled from\nfilamentous actin, intermediate filaments, and synthetic DNA nanotubes. In\ncontrast to prevalent theoretical assumptions, we find that bulk properties are\naffected by various inter-filament interactions. We present evidence that these\ninteractions can be merged into a single parameter in the frame of the glassy\nwormlike chain model. The interpretation of this parameter as a polymer\nspecific stickiness is consistent with observations from macro-rheological\nmeasurements and reptation behavior. Our findings demonstrate that stickiness\nshould generally not be ignored in semiflexible polymer models."
    },
    {
        "anchor": "Scattering from supramacromolecular structures: We study theoretically the scattering imprint of a number of branched\nsupramacromolecular architectures, namely, polydisperse stars and dendrimeric,\nhyperbranched structures. We show that polydispersity and nature of branching\nhighly influence the intermediate wavevector region of the scattering structure\nfactor, thus providing insight into the morphology of different aggregates\nformed in polymer solutions.",
        "positive": "Slow dynamics in glassy soft matter: Measuring, characterizing and modelling the slow dynamics of glassy soft\nmatter is a great challenge, with an impact that ranges from industrial\napplications to fundamental issues in modern statistical physics, such as the\nglass transition and the description of out-of-equilibrium systems. Although\nour understanding of these phenomena is still far from complete, recent\nsimulations and novel theoretical approaches and experimental methods have shed\nnew light on the dynamics of soft glassy materials. In this paper, we review\nthe work of the last few years, with an emphasis on experiments in four\ndistinct and yet related areas: the existence of two different glass states\n(attractive and repulsive), the dynamics of systems very far from equilibrium,\nthe effect of an external perturbation on glassy materials, and dynamical\nheterogeneity."
    },
    {
        "anchor": "Direct evaluation of attachment and detachment rate factors of atoms in\n  crystallizing supercooled liquids: Kinetic rate factors of crystallization have a direct effect on formation and\ngrowth of an ordered solid phase in supercooled liquids and glasses. Using\ncrystallizing Lennard-Jones liquid as an example, in the present work we\nperform a \\textit{direct} quantitative estimation of values of the key\ncrystallization kinetic rate factors -- the rate $g^{+}$ of particle\nattachments to a crystalline nucleus and the rate $g^{-}$ of particle\ndetachments from a nucleus. We propose a numerical approach, according to which\na statistical treatment of the results of molecular dynamics simulations was\nperformed without using any model functions and/or fitting parameters. This\napproach allows one to accurately estimate the critical nucleus size $n_{c}$.\nWe find that for the growing nuclei, whose sizes are larger than the critical\nsize $n_{c}$, the dependence of these kinetic rate factors on the nucleus size\n$n$ follows a power law. In the case of the subnucleation regime, when the\nnuclei are smaller than $n_{c}$, the $n$-dependence of the quantity $g^{+}$ is\nstrongly determined by the inherent microscopic properties of a system and this\ndependence cannot be described in the framework of any universal law (for\nexample, a power law). It has been established that the dependence of the\ngrowth rate of a crystalline nucleus on its size goes into the stationary\nregime at the sizes $n>3n_{c}$ particles.",
        "positive": "Infrasonic wave propagation in ultrasoft solids at low Reynolds numbers: The propagation of elastic waves in soft materials plays a crucial role in\nthe spatio-temporal transmission of mechanical signals, e.g. in biological\nmechanotransduction or in the failure of marginal solids. At high Reynolds\nnumbers $Re \\gg 1$, inertia dominates and wave propagation can be readily\nobserved. However, mechanical cues in soft and biological materials often occur\nat low $Re$, where waves are overdamped. Not only have low $Re$ waves been\ndifficult to observe in experiments, their theoretical description remains\nincomplete. In this paper, we present direct measurements of low $Re$ waves\npropagating in ordered and disordered soft solids, generated by an oscillating\npoint force induced by an optical trap. We derive an analytical theory for low\n$Re$ wave propagation, which is in excellent agreement with the experiments.\nOur results present both a new method to characterize wave propagation in soft\nsolids and a theoretical framework to understand how localized mechanical\nsignals can provoke a remote and delayed response."
    },
    {
        "anchor": "High-density liquid (HDL) adsorption at the supercooled water/vapor\n  interface and its possible relation to the second surface tension inflection\n  point: We investigate the properties of water along the liquid/vapor coexistence\nline in the supercooled regime down to the no-man's land. Extensive molecular\ndynamics simulations of the TIP4P/2005 liquid/vapor interface in the range 198\n-- 348 K allow us to locate the second surface tension inflection point with\nhigh accuracy at 283$\\pm$5 K, close to the temperature of maximum density\n(TMD). This temperature also coincides with the appearance of a density anomaly\nat the interface known as the apophysis. We relate the emergence of the\napophysis to the observation of HDL water adsorption in the proximity of the\nliquid/vapor interface.",
        "positive": "A Scaling Theory of the Competition between Interdiffusion and\n  Cross-Linking at Polymer Interfaces: We study theoretically situations where competition arises between an\ninterdiffusion process and a cross-linking chemical reaction at interfaces\nbetween pieces of the same polymer material. An example of such a situation is\nobservable in the formation of latex films, where, in the presence of a\ncross-linking additive, colloidal polymer particles initially in suspension\ncome at contact as the solvent evaporates, and, optimally, coalesce into a\ncontinuous coating. We considered the low cross-link density situation in a\nprevious paper (A. Aradian, E. Raphael, P.-G. de Gennes, Macromolecules 33,\n9444 (2000)), and presented a simple control parameter that determines the\nfinal state of the interface. In the present article, with the help of simple\nscaling arguments, we extend our description to higher cross-link densities. We\nprovide predictions for the strength of the interface in different favorable\nand unfavorable regimes, and discuss how it can be optimized."
    },
    {
        "anchor": "Soft meets hard -- how does freeze-thaw cycling affect the\n  microstructure of particle-stabilised emulsions?: The freeze-thaw cycling of particle-stabilised emulsions can alter the\nemulsion structure and stability. This could have significant consequences for\nusing particle stabilisation in industrial applications where increased\nstability is generally desirable. It is therefore important to characterise the\nbehaviour and stability of these composites under the influence of freeze-thaw\ncycles. Water-in-oil Pickering emulsions stabilised by poly(methyl\nmethacrylate) particles were subjected to freeze-thaw cycles of the continuous\nphase under two different conditions - uniform and non-uniform freezing.\nConfocal microscopy was used to study the emulsion behaviour and structure\nduring these processes. The effect of droplet size and cooling rate on\nuniformly frozen emulsions was also considered. The final structure of the\nemulsion after a single freeze-thaw cycle is strongly dependent on the freezing\nmethod. Uniformly frozen emulsions show crumpled droplet structures, while\nnon-uniformly frozen emulsions have a non-uniform structure containing\nfoam-like regions not observed in uniform freezing. Droplet size has little\neffect on the final structure of uniformly frozen emulsions, which we attribute\nto the Laplace pressure in the droplets being orders of magnitude smaller than\nthe pressure exerted on the droplets by the growing oil crystals. Cooling rate\nalso has little effect as droplets become surrounded and trapped by oil\ncrystals rapidly after samples reach the oil freezing temperature, irrespective\nof the speed at which they reached that temperature. When compared to\nsurfactant-stabilised emulsions undergoing the same process, we find emulsion\nstructure is recoverable in the surfactant case, whereas particle-stabilised\nemulsions are irreversibly altered.",
        "positive": "Particle motion during the compaction of granular matter: We track particle motions in a granular material subjected to compaction\nusing a laser scattering based imaging method where compaction is achieved\nthrough thermal cycling. Particle displacements in this jammed fluid correlate\nstrongly with rearrangments of the Voronoi cells defining the local spatial\npartitioning about the particles, similar to previous observations of Rahman on\ncooled liquids. Our observations provide further evidence of commonalities\nbetween particle dynamics in granular matter close to jamming and supercooled\nliquids."
    },
    {
        "anchor": "Evidence of phonon-assisted tunnelling in electrical conduction through\n  DNA molecules: We propose a phonon-assisted tunnelling model for explanation of conductivity\ndependence on temperature and temperature-dependent I-V characteristics in\ndeoxyribonucleic acid (DNA) molecules. The capability of this model for\nexplanation of conductivity peculiarities in DNA is illustrated by comparison\nof the temperature dependent I-V data extracted from some articles with\ntunnelling rate dependences on temperature and field strength computed\naccording to the phonon-assisted tunnelling theory.\n  PACS Codes: 87.15.-v, 71.38.-k, 73.40.Gk",
        "positive": "Magnon condensation into Q-ball in 3He-B: The theoretical prediction of Q-balls in relativistic quantum fields is\nrealized here experimentally in superfluid 3He-B. The condensed-matter analogs\nof relativistic Q-balls are responsible for an extremely long lived signal of\nmagnetic induction -- the so-called Persistent Signal -- observed in NMR at the\nlowest temperatures. This Q-ball is another representative of a state with\nphase coherent precession of nuclear spins in 3He-B, similar to the well known\nHomogeneously Precessing Domain which we interpret as Bose condensation of spin\nwaves -- magnons. At large Q the effect of self-localization is observed. In\nthe language of relativistic quantum fields it is caused by interaction between\nthe charged and neutral fields, where the neutral field provides the potential\nfor the charged one. In the process of self-localization the charged field\nmodifies locally the neutral field so that the potential well is formed in\nwhich the charge is condensed."
    },
    {
        "anchor": "Role of structural relaxations and vibrational excitations in the\n  high-frequency dynamics of liquids and glasses: We present theoretical investigation on the high-frequency collective\ndynamics in liquids and glasses at microscopic length scales and terahertz\nfrequency region based on the mode-coupling theory for ideal liquid-glass\ntransition. We focus on recently investigated issues from\ninelastic-X-ray-scattering and computer-simulation studies for dynamic\nstructure factors and longitudinal and transversal current spectra: the\nanomalous dispersion of the high-frequency sound velocity and the nature of the\nlow-frequency excitation called the boson peak. It will be discussed how the\nsound mode interferes with other low-lying modes present in the system.\nThereby, we provide a systematic explanation of the anomalous sound-velocity\ndispersion in systems -- ranging from high temperature liquid down to deep\ninside the glass state -- in terms of the contributions from the\nstructural-relaxation processes and from vibrational excitations called the\nanomalous-oscillation peak (AOP). A possibility of observing negative\ndispersion -- the {\\em decrease} of the sound velocity upon increase of the\nwave number -- is argued when the sound-velocity dispersion is dominated by the\ncontribution from the vibrational dynamics. We also show that the low-frequency\nexcitation, observable in both of the glass-state longitudinal and transversal\ncurrent spectra at the same resonance frequency, is the manifestation of the\nAOP. As a consequence of the presence of the AOP in the transversal current\nspectra, it is predicted that the transversal sound velocity also exhibits the\nanomalous dispersion. These results of the theory are demonstrated for a model\nof the Lennard-Jones system.",
        "positive": "Clarifying the controversy of the Tg depression in polystyrene thin\n  films: The glass transition temperature ($T_g$) of polymer thin films has been a\nsubject of controversy in the last two decades. (Pseudo)thermodynamic\ndeterminations of $T_g$ generally suggest a significant depression, whereas the\nmolecular mobility is found to be unchanged. The present study clarifies this\napparent controversy by assuming that the $T_g$ in thin films is determined not\nonly by the molecular mobility but also by the thickness of the film. This\nhypothesis is supported by the analysis of literature results on polystyrene\nthin films showing that the $T_g$ dependence on the cooling rate obtained on\nsamples with different thicknesses can be rescaled onto a master curve. The\nthickness dependence of $T_g$ is quantitatively captured by an equilibration\nmechanism based on free volume holes diffusion. This dependence emerges from\nthe ability of thinner films to maintain equilibrium, due to the shorter\ndistance free volume holes have to diffuse to the polymer interface, the\nmolecular motion determining the diffusion coefficient being thickness\nindependent."
    },
    {
        "anchor": "Self-Diffusion of Glycerol in $\u03b3$-Alumina Nanopores: Understanding\n  the Effect of Pore Saturation on the Dynamics of Confined Polyalcohols: Molecular Dynamics simulations of glycerol confined in $\\gamma$-Al$_2$O$_3$\nslit nanopores are used to explain controversial and inconsistent observations\nreported in the literature regarding the dynamics of viscous fluids in confined\ngeometries. Analysing the effects of the degree of confinement and pore\nsaturation in this system, we found that the presence of the solid/liquid\ninterface and the liquid/gas interface in partially saturated pores are the\nmain contributors for the disruption of the hydrogen bond network of glycerol.\nDespite the reduction of hydrogen bonds between glycerol molecules caused by\nthe presence of the solid, glycerol molecules near the solid surface can\nestablish hydrogen bonds with the hydroxyl groups of $\\gamma$-Al$_2$O$_3$ that\nsignificantly slow-down the dynamics of the confined fluid compared to the bulk\nliquid. On the other hand, the disruption of the hydrogen bond network caused\nby the liquid/gas interface in unsaturated pores reduces significantly the\nnumber of hydrogen bonds between glycerol molecules and results in a faster\ndynamics than in the bulk liquid. Therefore, we suggest that the discrepancies\nreported in the literature are a consequence of measurements carried out under\ndifferent pore saturation conditions.",
        "positive": "Supported bilayers: combined specular and diffuse x-ray scattering: A new method is proposed for the analysis of specular and off-specular\nreflectivity from supported lipid bilayers. Both thermal fluctuations and the\n\"static\" roughness induced by the substrate are carefully taken into account.\nExamples from supported bilayers and more complex systems comprising a bilayer\nadsorbed or grafted on the substrate and another \"floating\" bilayer are given.\nThe combined analysis of specular and off-specular reflectivity allows the\nprecise determination of the structure of adsorbed and floating bilayers, their\ntension, bending rigidity and interaction potentials. We show that this new\nmethod gives a unique opportunity to investigate phenomena like protusion modes\nof adsorbed bilayers and opens the way to the investigation of more complex\nsystems including different kinds of lipids, cholesterol or peptides."
    },
    {
        "anchor": "Primitive model electrolytes. A comparison of the HNC approximation for\n  the activity coefficient with Monte Carlo data: Accuracy of the mean activity coefficient expression\n(Hansen-Vieillefosse-Belloni equation), valid within the hypernetted chain\n(HNC) approximation, was tested in a wide concentration range against new Monte\nCarlo (MC) data for +1:-1 and +2:-2 primitive model electrolytes. The\nexpression has an advantage that the excess chemical potential can be obtained\ndirectly, without invoking the time consuming Gibbs-Duhem calculation. We found\nthe HNC results for the mean activity coefficient to be in good agreement with\nthe machine calculations performed for the same model. In addition, the\nthermodynamic consistency of the HNC approximation was tested. The mean\nactivity coefficients, calculated via the Gibbs-Duhem equation, seem to follow\nthe MC data slightly better than the Hansen-Vieillefosse-Belloni expression.\nFor completeness of the calculation, the HNC excess internal energies and\nosmotic coefficients are also presented. These results are compared with the\ncalculations based on other theories commonly used to describe electrolyte\nsolutions, such as the mean spherical approximation, Pitzer's extension of the\nDebye-H\\\"uckel theory, and the Debye-H\\\"uckel limiting law.",
        "positive": "Bulk viscosity of the Lennard-Jones system at the triple point by\n  dynamical Non Equilibrium Molecular Dynamics: Non-equilibrium Molecular Dynamics (NEMD) calculations of the bulk viscosity\nof the triple point Lennard-Jones fluid are performed with the aim of\ninvestigating the origin of the observed disagreement between Green-Kubo\nestimates and previous NEMD data. We show that a careful application of the\nDoll's perturbation field, the dynamical NEMD method, the instantaneous form of\nthe perturbation and the \"subtraction technique\" provides a NEMD estimate of\nthe bulk viscosity at zero field in full agreement with the value obtained by\nthe Green-Kubo formula. As previously reported for the shear viscosity, we find\nthat the bulk viscosity exhibits a large linear regime with the field intensity\nwhich confirms the Lennard-Jones fluid as a genuine Newtonian fluid even at\ntriple point."
    },
    {
        "anchor": "Global equation of state and phase transitions of the hard disc systems: The hard disc system plays a fundamental role in the study of two-dimensional\nmatters [1-3]. High-precision compressibility data from computer simulations\nhave been reported for all the phases and phase transition regions [4-15]. In\nparticular, Bernard and Krauth (Phys. Rev. Lett., 107, 155704, 2011) [10]\npresented a complete and accurate picture of the phase transitions of the hard\ndisc system with simulation results. However, thorough descriptions of the\nsystem depend on analytical equations of state (EoS) over the entire density\nrange. While majority of EoS published are for the stable fluid region only\n[1,16], few attempted the liquid-hexact transition region (Phys. Rev. Lett.,\n11, 241, 1963 [17]; Phys. Rev. E. 63, 042201, 2001 [18]; 74, 061106, 2006\n[19]). All the EoS currently available are incapable of quantitative\ndescriptions of the phase transitions. Here we construct a simple EoS to\nreproduce high-precision simulation data for all the stable liquid,\nliquid-hexatic transition region and hexatic phase. A global EoS is then\nobtained when the new EoS is smoothly united with a revisited EoS for the solid\nphase. Using this global equation, we are able to accurately identify all the\nphases and the phase transitions from the stable liquid to hexatic, then to\nsolid phases. The liquid-hexatic transition is found to be of weak first-order,\nnamely discontinuous in density and the Gibbs free energy while continuous in\nentropy and the Helmholtz free energy. The hexatic-solid transition is a\ncontinuous high-order phase transition.",
        "positive": "Towards local rheology of emulsions under Couette flow using Dynamic\n  Light Scattering: We present local velocity measurements in emulsions under shear using\nheterodyne Dynamic Light Scattering. Two emulsions are studied: a dilute system\nof volume fraction $\\phi=20$ % and a concentrated system with $\\phi=75$ %.\nVelocity profiles in both systems clearly show the presence of wall slip. We\ninvestigate the evolution of slip velocities as a function of shear stress and\ndiscuss the validity of the corrections for wall slip classically used in\nrheology. Focussing on the bulk flow, we show that the dilute system is\nNewtonian and that the concentrated emulsion is shear-thinning. In the latter\ncase, the curvature of the velocity profiles is compatible with a\nshear-thinning exponent of 0.4 consistent with global rheological data.\nHowever, even if individual profiles can be accounted for by a power-law fluid\n(with or without a yield stress), we could not find a fixed set of parameters\nthat would fit the whole range of applied shear rates. Our data thus raise the\nquestion of the definition of a global flow curve for such a concentrated\nsystem. These results show that local measurements are a crucial complement to\nstandard rheological tools. They are discussed in light of recent works on soft\nglassy materials."
    },
    {
        "anchor": "A topological method to characterize tapped granular media from the\n  position of the particles: We use the first Betti number of a complex to characterize the morphological\nstructure of granular samples in mechanical equilibrium. We analyze\ntwo-dimensional granular packings after a tapping process by means of both\nsimulations and experiments. States with equal packing fraction obtained with\ndifferent tapping intensities are distinguished after the introduction of a\nfiltration parameter which determines the particles (nodes in the network) that\nare joined by an edge. We first use numerical simulations to characterize the\neffect of the precision in the particles localization by artificially adding\ndifferent levels of noise in this magnitude. The outcomes obtained for the\nsimulations are then compared with the experimental results allowing a clear\ndistinction of experimental packings that have the same density. This is\naccomplished by just using the position of the particles and no other\ninformation about the possible contacts, or magnitude of forces.",
        "positive": "Self-assembled porous media from particle-stabilized emulsions: We propose a new mechanism to create self-assembled porous media with highly\ntunable geometrical properties and permeabilities: We first allow a\nparticle-stabilized emulsion to form from a mixture of two fluids and colloidal\nparticles. Then, either one fluid phase or the particle layer is solidified,\nwhich can be achieved by techniques such as polymerization or freezing. Based\non computer simulations we demonstrate that modifying only the particle\nwettability or concentration results in porous structures with a wide range of\npore sizes and a permeability that can be varied by up to three orders of\nmagnitude. We then discuss optimization of these properties for self-assembled\nfilters or reactors and conclude that structures based on so-called \"bijels\"\nare most suitable candidates."
    },
    {
        "anchor": "Heat Transfer in Superfluids: Effect of Gravity: We discuss the influence of an external field on energy transport in\nsuperfluid. He-II is not isothermal in presence of Earth gravity; instead, it\nsupports finite temperature gradient given by a Fourier-like equation. We\ncalculate asymptotic behavior of the effective heat resistance in the vicinity\nof the $\\lambda$-transition.",
        "positive": "A symmetrical method to obtain shear moduli from microrheology: Passive microrheology typically deduces shear elastic loss and storage moduli\nfrom displacement time series or mean-squared displacement (MSD) of thermally\nfluctuating probe particles in equilibrium materials. Common data analysis\nmethods use either Kramers-Kronig (KK) transformations or functional fitting to\ncalculate frequency-dependent loss and storage moduli. We propose a new\nanalysis method for passive microrheology that avoids the limitations of both\nof these approaches. In this method, we determine both real and imaginary\ncomponents of the complex, frequency-dependent response function $\\chi(\\omega)\n= \\chi^{\\prime}(\\omega)+i\\chi^{\\prime\\prime}(\\omega)$ as direct integral\ntransforms of the MSD of thermal particle motion. This procedure significantly\nimproves the high-frequency fidelity of $\\chi(\\omega)$ relative to the use of\nKK transformation, which has been shown to lead to artifacts in\n$\\chi^{\\prime}(\\omega)$. We test our method on both model data and experimental\ndata. Experiments were performed on solutions of worm-like micelles and dilute\ncollagen solutions. While the present method agrees well with established\nKK-based methods at low frequencies, we demonstrate significant improvement at\nhigh frequencies using our symmetric analysis method, up to almost the\nfundamental Nyquist limit."
    },
    {
        "anchor": "Structure, dynamics and phase behavior of short rod inclusions dissolved\n  in a colloidal membrane: Inclusions dissolved in an anisotropic quasi-2D membrane acquire new types of\ninteractions that can drive assembly of complex structures and patterns. We\nstudy colloidal membranes composed of a binary mixture of long and short rods,\nsuch that the length ratio of the long to short rods is approximately two. At\nvery low volume fractions, short rods dissolve in the membrane of long rods by\nstrongly anchoring to the membrane polymer interface. At higher fractions, the\ndissolved short rods phase separate from the background membrane, creating a\ncomposite structure comprised of bilayer droplets enriched in short rods that\ncoexist with the background monolayer membrane. These results demonstrate that\ncolloidal membranes serve as a versatile platform for assembly of soft\nmaterials, while simultaneously providing new insight into universal\nmembrane-mediated interactions.",
        "positive": "Spatial interference of coherent atomic waves by manipulation of the\n  internal quantum state: A trapped 87Rb Bose-Einstein condensate is initially put into a superposition\nof two internal states. Under the effect of gravity and by means of a second\ntransition, we prepare two vertically displaced condensates in the same\ninternal state. These constitute two coherent sources of matter waves with\nadjustable spatial separation. Fringe patterns, observed after free expansion,\nare associated with the interplay between internal and external degrees of\nfreedom and substantially agree with those for a double slit experiment."
    },
    {
        "anchor": "Time-resolved thermal lens spectroscopy of glassy dynamics in\n  supercooled liquids: theory and experiments: Specific heat and linear thermal expansivity are fundamental thermal dynamics\nand have been proven as interesting relaxing quantities to investigate in glass\ntransition and glassy state. However, their possibility has much less been\nexploited compared to mechanical and dielectric susceptibilities due to the\nlimited spectroscopy bandwidth. This work reports on simultaneous spectroscopy\nof the two by making use of ultrafast time-resolved thermal lens (TL)\nspectroscopy. Detailed modeling of the thermoelastic transients of a relaxing\nsystem subjected to ultrashort laser heating is presented to describe the TL\nresponse. The model has been applied to analyze a set of experimentally\nrecorded TL waveforms, allowing the determination of relaxation strength and\nrelaxation frequency from sub-kilohertz to sub-100 MHz and in a wide\ntemperature range from 200-280 K.",
        "positive": "Theory on quench-induced pattern formation: Application to the isotropic\n  to smectic-A phase transitions: During catastrophic processes of environmental variations of a thermodynamic\nsystem, such as rapid temperature decreasing, many novel and complex patterns\noften form.\n  To understand such phenomena, a general mechanism is proposed based on the\ncompetition between heat transfer and conversion of heat to other energy forms.\nWe apply it to the smectic-A filament growth process during quench-induced\nisotropic to smectic-A phase transition. Analytical forms for the buckling\npatterns are derived and we find good agreement with experimental observation\n[Phys. Rev. {\\bf E55} (1997) 1655]. The present work strongly indicates that\nrapid cooling will lead to structural transitions in the smectic-A filament at\nthe molecular level to optimize heat conversion. The force associated with this\npattern formation process is estimated to be in the order of $10^{-1}$\npiconewton."
    },
    {
        "anchor": "Theory of sound attenuation in amorphous solids from nonaffine motions: We present a theoretical derivation of acoustic phonon damping in amorphous\nsolids based on the nonaffine response formalism for the viscoelasticity of\namorphous solids. The analytical theory takes into account the nonaffine\ndisplacements in transverse waves and is able to predict both the ubiquitous\nlow-energy diffusive damping $\\sim k^{2}$, as well as a novel contribution to\nthe Rayleigh damping $\\sim k^{4}$ at higher wavevectors and the crossover\nbetween the two regimes observed experimentally. The coefficient of the\ndiffusive term is proportional to the microscopic viscous (Langevin-type)\ndamping in particle motion (which arises from anharmonicity), and to the\nnonaffine correction to the static shear modulus, whereas the Rayleigh damping\nemerges in the limit of low anharmonicity, consistent with previous\nobservations and macroscopic models. Importantly, the $k^4$ Rayleigh\ncontribution derived here does not arise from harmonic disorder or elastic\nheterogeneity effects and it is the dominant mechanism for sound attenuation in\namorphous solids as recently suggested by molecular simulations.",
        "positive": "Experimental Demonstration of the Stabilization of Colloids by Addition\n  of Salt: We demonstrate a general non--Derjaguin-Landau-Verwey-Overbeek method to\nstabilize colloids in liquids. By this method, colloidal particles that\ninitially form unstable suspension and sediment from the liquid are stabilized\nby the addition of salt to the suspending liquid. Yet, the salt is not expected\nto adsorb or directly interact with the surface of the colloids. For the method\nto work, the liquid should be a mixture, and the salt needs to be antagonistic\nsuch that each ion is preferentially solvated by a different component of the\nmixture. The stabilization may depend on the salt content, mixture composition,\nor distance from the mixture's coexistence line."
    },
    {
        "anchor": "Journey of an intruder through the fluidisation and jamming transitions\n  of a dense granular media: We study experimentally the motion of an intruder dragged into an amorphous\nmonolayer of horizontally vibrated grains at high packing fractions. This\nmotion exhibits two transitions. The first transition separates a continuous\nmotion regime at comparatively low packing fractions and large dragging force\nfrom an intermittent motion one at high packing fraction and low dragging\nforce. Associated to these different motions, we observe a transition from a\nlinear rheology to a stiffer response. We thereby call \"fluidisation\" this\nfirst transition. A second transition is observed within the intermittent\nregime, when the intruder's motion is made of intermittent bursts separated by\nlong waiting times. We observe a peak in the relative fluctuations of the\nintruder's displacements and a critical scaling of the burst amplitudes\ndistributions. This transition occurs at the jamming point characterized in a\nprevious study and defined as the point where the static pressure (i.e. the\npressure measured in the absence of vibration) vanishes. Investigating the\nmotion of the surrounding grains, we show that below the fluidisation\ntransition, there is a permanent wake of free volume behind the intruder. This\ntransition is marked by the evolution of the reorganization patterns around the\nintruder, which evolve from compact aggregates in the flowing regime to\nlong-range branched shapes in the intermittent regime, suggesting an increasing\nrole of the stress fluctuations. Remarkably, the distributions of the kinetic\nenergy of these reorganization patterns also exhibits a critical scaling at the\njamming transition.",
        "positive": "Long Range Moves for High Density Polymer Simulations: Monte Carlo simulations of proteins are hindered by the system's high density\nwhich often makes local moves ineffective. Here we devise and test a set of\nlong range moves that work well even when all sites of a lattice simulation are\nfilled. We demonstrate that for a 27-mer cube, the ground state of random\nheteropolymers can quickly be reached. We discuss results for 48-mer systems\nwhere the ground state is known exactly. For ten sequences that were examined,\nthe introduction of long range moves speeds up the search for the ground state\nby about one order of magnitude. The method is compared to a fast folding chain\ngrowth algorithm that had previously been used with much success. The new\nalgorithm here appears to be more efficient. The point is illustrated by the\nfolding of an 80-mer four-helix bundle considered previously."
    },
    {
        "anchor": "Modelling of the influence of nanostructures' sizes on lattice\n  parameters: Computer modeling of formation of the one-dimensional and three-dimensional\nmonatomic nanostructures by the method of atom-atom potentials was done. The\narrangement of atoms was defined on the basis of the energy minimum. Our\ncalculations have shown that the distance between the nearest atoms depends on\nnumber of atoms, thus atoms on boundary of grains of nanoparticles have more\nloose packing than in the volume. In three-dimensional nanostructures at\nreduction of their sizes increase of the disorder of atoms on positions is\nobserved. Examination of model nanostructures constructed of bi-atomic\nmolecules was also carried out. It is shown that distance between the nearest\nmolecules and their orientation depend on number of molecules surrounding them.\nMolecules on boundary of grains of nanoparticles have more friable packing than\nin the volume. As in the linear chain, and three-dimensional nanostructures\nconstructed of bi-atomic molecules, not only the disorder on positions of\nmolecules depending on the sizes of nanoparticles, but also the orientation\ndisorder is observed. At increase of the sizes of nanostructures the lattice in\nvolume becomes more ordered than on boundaries of nanoparticles grains.",
        "positive": "Topological analysis of polymeric melts: Chain length effects and\n  fast-converging estimators for entanglement length: Primitive path analyses of entanglements are performed over a wide range of\nchain lengths for both bead spring and atomistic polyethylene polymer melts.\nEstimators for the entanglement length N_e which operate on results for a\nsingle chain length N are shown to produce systematic O(1/N) errors. The\nmathematical roots of these errors are identified as (a) treating chain ends as\nentanglements and (b) neglecting non-Gaussian corrections to chain and\nprimitive path dimensions. The prefactors for the O(1/N) errors may be large;\nin general their magnitude depends both on the polymer model and the method\nused to obtain primitive paths. We propose, derive and test new estimators\nwhich eliminate these systematic errors using information obtainable from the\nvariation of entanglement characteristics with chain length. The new estimators\nproduce accurate results for N_e from marginally entangled systems. Formulas\nbased on direct enumeration of entanglements appear to converge faster and are\nsimpler to apply."
    },
    {
        "anchor": "On droplets coalescence in a quasi-2D fluid: The coalescence of droplets plays a crucial role in nature and modern\ntechnology. Various experimental and theoretical studies explored droplet\ndynamics in 3D and on 2D solid or liquid substrates. In this paper, we\ndemonstrate the coalescence of isotropic droplets confined in thin quasi-2D\nliquids -- overheated smectic films. We observe the merging of micrometer-sized\nflat droplets using high-speed-imaging and analyse the shape transformations of\nthe droplets on the timescale of milliseconds. Our studies reveal the scaling\nlaws of the coalescence time, which exhibits a different dependence on the\ndroplet geometry than in case of droplets on a solid substrate. A theoretical\nmodel is proposed to explain the difference in behaviour.",
        "positive": "Crystal growth in nano-confinement: Subcritical cavity formation and\n  viscosity effects: We report on the modeling of the formation of a cavity at the surface of\ncrystals confined by a flat wall during growth in solution. Using a continuum\nthin film model, we discuss two phenomena that could be observed when\ndecreasing the thickness of the liquid film between the crystal and the wall\ndown to the nanoscale. First, in the presence of an attractive van der Waals\ncontribution to the disjoining pressure, the formation of the cavity becomes\nsub-critical, i.e., discontinuous. In addition, there is a minimum\nsupersaturation required to form a cavity. Second, when the thickness of the\nliquid film between the crystal and the substrate reaches the nanoscale,\nviscosity becomes relevant and hinders the formation of the cavity. We\ndemonstrate that there is a critical value of the viscosity above which no\ncavity will form. The critical viscosity increases as the square of the\nthickness of the liquid film. A quantitative discussion of model materials such\nas Calcite, Sodium Chlorate, Glucose and Sucrose is provided."
    },
    {
        "anchor": "Structure of plastically compacting granular packings: The developing structure in systems of compacting ductile grains were studied\nexperimentally in two and three dimensions. In both dimensions, the peaks of\nthe radial distribution function were reduced, broadened, and shifted compared\nwith those observed in hard disk- and sphere systems. The geometrical\nthree--grain configurations contributing to the second peak in the radial\ndistribution function showed few but interesting differences between the\ninitial and final stages of the two dimensional compaction. The evolution of\nthe average coordination number as function of packing fraction is compared\nwith other experimental and numerical results from the literature. We conclude\nthat compaction history is important for the evolution of the structure of\ncompacting granular systems.",
        "positive": "Discrete approach to incoherent excitations in conductors: Keeping the discretness of the reciprocal space we calculate the spectrum of\nincoherent electron-hole excitations in the conducting Fermi liquids. The metod\nis illustrated on the well-known jellium model within the random phase\napproximation. It also leads to the formulation os a sum rule from which we get\nthe details os dispersion curve for the collective plasmon mode. The notion of\ntime averaging in the discrete approach is briefly recalled."
    },
    {
        "anchor": "Superfluidity versus Bloch oscillations in confined atomic gases: We study the superfluid properties of (quasi) one-dimensional bosonic atom\ngases/liquids in traps with finite geometries in the presence of strong quantum\nfluctuations. Driving the condensate with a moving defect we find the\nnucleation rate for phase slips using instanton techniques. While phase slips\nare quenched in a ring resulting in a superfluid response, they proliferate in\na tube geometry where we find Bloch oscillations in the chemical potential.\nThese Bloch oscillations describe the individual tunneling of atoms through the\ndefect and thus are a consequence of particle quantization.",
        "positive": "Coarse grained molecular simulations of membrane adhesion domains: We use a coarse grained molecular model of supported lipid bilayers to study\nthe formation of adhesion domains. We find that this process is a first order\nphase transition, triggered by a combination of pairwise short range attractive\ninteractions between the adhesion bonds and many-body Casimir-like\ninteractions, mediated by the membrane thermal undulations. The simulation\nresults display an excellent agreement with the recently proposed Weil-Farago\n2D lattice model, in which the occupied and empty sites represent,\nrespectively, the adhesion bonds and unbound segments of the membrane. A second\nphase transition, into a hexatic phase, is observed when the attraction between\nthe adhesion bonds is further strengthened."
    },
    {
        "anchor": "Colloidal particle adsorption at liquid interfaces: Capillary driven\n  dynamics and thermally activated kinetics: The adsorption of single colloidal microparticles (0.5--1 $\\mu$m radius) at a\nwater-oil interface has been recently studied experimentally using digital\nholographic microscopy [Kaz \\textit{et al., Nat. Mater.}, 2012, \\textbf{11},\n138--142]. An initially fast adsorption dynamics driven by capillary forces is\nfollowed by an unexpectedly slow relaxation to equilibrium that is logarithmic\nin time and can span hours or days. The slow relaxation kinetics has been\nattributed to the presence of surface \"defects\" with nanoscale dimensions\n(1--5\\,nm) that induce multiple metastable configurations of the contact line\nperimeter. A kinetic model considering thermally activated transitions between\nsuch metastable configurations has been proposed [Colosqui \\textit{et al.,\nPhys. Rev. Lett.}, 2013, \\textbf{111}, 028302] to predict both the relaxation\nrate and the crossover point to the slow logarithmic regime. However, the\nadsorption dynamics observed experimentally before the crossover point has\nremained unstudied. In this work, we propose a Langevin model that is able to\ndescribe the entire adsorption process of single colloidal particles by\nconsidering metastable states produced by surface defects and thermal motion of\nthe particle and liquid interface. Invoking the fluctuation dissipation\ntheorem, we introduce a drag term that considers significant dissipative forces\ninduced by thermal fluctuations of the liquid interface. Langevin dynamics\nsimulations based on the proposed adsorption model yield close agreement with\nexperimental observations for different microparticles, capturing the crossover\nfrom (fast) capillary driven dynamics to (slow) thermally activated kinetics.",
        "positive": "Vorticity structuring and Taylor-like velocity rolls triggered by\n  gradient shear bands: We suggest a novel mechanism by which vorticity structuring and Taylor-like\nvelocity rolls can form in complex fluids, triggered by the linear instability\nof one dimensional gradient shear banded flow. We support this with a numerical\nstudy of the diffusive Johnson-Segalman model. In the steady vorticity\nstructured state, the thickness of the interface between the bands remains\nfinite in the limit of zero stress diffusivity, presenting a possible challenge\nto the accepted theory of shear banding."
    },
    {
        "anchor": "Inducing a bound state between active particles: We show that two active particles can form a bound state by coupling to a\ndriven nonequilibrium environment. We specifically investigate the case of two\nmutually noninteracting run-and-tumble probes moving on a ring, each in\nshort-range interaction with driven colloids. Under conditions of time-scale\nseparation, these active probes become trapped in bound states. In fact, the\nbound state appears at high enough persistence (low effective temperature).\nFrom the perspective of a co-moving frame, where colloids are in thermal\nequilibrium and the probes are active and driven, an appealing analogy appears\nwith Cooper pairing, as electrons can be viewed as run-and-tumble particles in\na pilot-wave picture.",
        "positive": "Glassy Dislocation Dynamics in 2-D Colloidal Dimer Crystals: Although glassy relaxation is typically associated with disorder, here we\nreport on a new type of glassy dynamics relating to dislocations within 2-D\ncrystals of colloidal dimers. Previous studies have demonstrated that\ndislocation motion in dimer crystals is restricted by certain particle\norientations. Here, we drag an optically trapped particle through such dimer\ncrystals, creating dislocations. We find a two-stage relaxation response where\ninitially dislocations glide until encountering particles that cage their\nmotion. Subsequent relaxation occurs logarithmically slowly through a second\nprocess where dislocations hop between caged configurations. Finally, in\nsimulations of sheared dimer crystals, the dislocation mean squared\ndisplacement displays a caging plateau typical of glassy dynamics. Together,\nthese results reveal a novel glassy system within a colloidal crystal."
    },
    {
        "anchor": "PECVD and PEALD on polymer substrates (part I): Fundamentals and\n  analysis of plasma activation and thin film growth: This feature article considers the analysis of the initial states of film\ngrowth on polymer substrates. The assembled results are based on the\ncooperation between research groups in the field of plasma physics, chemistry,\nelectric as well as mechanical engineering over the last years, mostly within\nthe frame of the transregional project SFB-TR 87 (\"Pulsed high power plasmas\nfor the synthesis of nanostructured functional layers\"). This feature article\naims at bridging the gap between the understanding of plasma processes in the\ngas phase and the resulting surface and interface processes of the polymer. The\nresults show that interfacial adhesion and initial film growth can be well\ncontrolled and even predicted based on the combination of analytical\napproaches.",
        "positive": "Dependence of the surface tension on the shape of surface boundary: We numerically check that the surface tension of membranes is independent of\nthe shape of surface boundary. The surface tension is calculated by means of\nthe Monte Carlo simulation technique on two types of cylinders made of rubans\nof size $L_1$ and $L_2$, where the rubans are the same for the projected area\nand different in the ratio $L_1/L_2$. The difference of the surface tension\ndisappears in the thermodynamic limit in both models of Helfrich-Polyakov and\nLandau-Ginzburg."
    },
    {
        "anchor": "Stress-induced anisotropy in granular materials: fabric, stiffness, and\n  permeability: The loading of a granular material induces anisotropies of the particle\narrangement (fabric) and of the material's strength, incremental stiffness, and\npermeability. Thirteen measures of fabric anisotropy are developed, which are\narranged in four categories: as preferred orientations of the particle bodies,\nthe particle surfaces, the contact normals, and the void space. Anisotropy of\nthe voids is described through image analysis and with Minkowski tensors. The\nthirteen measures of anisotropy change during loading, as determined with\nthree-dimensional discrete element simulations of biaxial plane strain\ncompression with constant mean stress. Assemblies with four different particle\nshapes were simulated. The measures of contact orientation are the most\nresponsive to loading, and they change greatly at small strains, whereas the\nother measures lag the loading process and continue to change beyond the state\nof peak stress and even after the deviatoric stress has nearly reached a steady\nstate. The paper implements a methodology for characterizing the incremental\nstiffness of a granular assembly during biaxial loading, with orthotropic\nloading increments that preserve the principal axes of the fabric and stiffness\ntensors. The linear part of the hypoplastic tangential stiffness is monitored\nwith oedometric loading increments. This stiffness increases in the direction\nof the initial compressive loading but decreases in the direction of extension.\nAnisotropy of this stiffness is closely correlated with a particular measure of\nthe contact fabric. Permeabilities are measured in three directions with\nlattice Boltzmann methods at various stages of loading and for assemblies with\nfour particle shapes. Effective permeability is negatively correlated with the\ndirectional mean free path and is positively correlated with pore width.",
        "positive": "Multiple ordering transitions in a chiral liquid: We present here a numerical study of a lattice model of a chiral liquid. The\nlow symmetry of the favoured local structure depresses the freezing point to\nreveal an exotic liquid-liquid transition characterised by the appearance of an\nextended chirality,prior to freezing. What mechanisms impede crystallisation in\nliquids with low molecular symmetry ? The ordered liquid can be readily\nsupercooled to zero temperature, as the combination of critical slowing down\nand competing crystal polymorphs results in a dramatically slow crystallisation\nprocess."
    },
    {
        "anchor": "Height Distribution and Orientation of Colloidal Dumbbells Near a Wall: Geometric confinement strongly influences the behavior of microparticles in\nliquid environments. However, to date, nonspherical particle behaviors close to\nconfining boundaries, even as simple as planar walls, remain largely\nunexplored. Here, we measure the height distribution and orientation of\ncolloidal dumbbells above walls by means of digital in-line holographic\nmicroscopy. We find that while larger dumbbells are oriented almost parallel to\nthe wall, smaller dumbbells of the same material are surprisingly oriented at\npreferred angles. We determine the total height-dependent force acting on the\ndumbbells by considering gravitational effects and electrostatic particle-wall\ninteractions. Our modeling reveals that at specific heights both net forces and\ntorques on the dumbbells are simultaneously below the thermal force and energy,\nrespectively, which makes the observed orientations possible. Our results\nhighlight the rich near-wall dynamics of nonspherical particles, and can\nfurther contribute to the development of quantitative frameworks for\narbitrarily-shaped microparticle dynamics in confinement.",
        "positive": "Efficient $d$-dimensional molecular dynamics simulations for studies of\n  the glass-jamming transition: We develop an algorithm suitable for parallel molecular dynamics simulations\nin $d$ spatial dimensions and describe its implementation in C++. All routines\nwork in arbitrary $d$; the maximum simulated $d$ is limited only by available\ncomputing resources. These routines include several that are particularly\nuseful for studies of the glass/jamming transition, such as SWAP Monte Carlo\nand FIRE energy minimization. Scaling of simulation runtimes with the number of\nparticles $N$ and number of simulation threads $n_{\\rm threads}$ is comparable\nto popular MD codes such as LAMMPS. The efficient parallel implementation\nallows simulation of systems that are much larger than those employed in\nprevious high-dimensional glass-transition studies. As a demonstration of the\ncode's capabilities, we show that supercooled $d = 6$ liquids can possess\ndynamics that are substantially more heterogeneous and experience a breakdown\nof the Stokes-Einstein relation that is substantially stronger than previously\nreported, owing at least in part to the much smaller system sizes employed in\nearlier simulations."
    },
    {
        "anchor": "The near and far of a pair of magnetic capillary disks: Control on microscopic scales depends critically on our ability to manipulate\ninteractions with different physical fields. The creation of micro-machines\ntherefore requires us to understand how multiple fields, such as surface\ncapillary or electro-magnetic, can be used to produce predictable behaviour.\nRecently, a spinning micro-raft system was developed that exhibited both static\nand dynamic self-assembly [Wang et al. (2017) Sci. Adv. 3, e1602522]. These\nrafts employed both capillary and magnetic interactions and, at a critical\ndriving frequency, would suddenly change from stable orbital patterns to static\nassembled structures. In this paper, we explain the dynamics of two interacting\nmicro-rafts through a combination of theoretical models and experiments. This\nis first achieved by identifying the governing physics of the orbital patterns,\nthe assembled structures, and the collapse separately. We find that the orbital\npatterns are determined by the short range capillary interactions between the\ndisks, while the explanations of the other two behaviours only require the\ncapillary far field. Finally we combine the three models to explain the\ndynamics of a new micro-raft experiment.",
        "positive": "Water inside charged nanoslits: Structure and Dielectric study with a\n  novel water model FAB/$\u03b5$: In this work, the dielectric behavior of water inside charged nanoslit of\ngraphene is studied to analized the water molecules under electrical\nconfinement; through polarizing the nanoslit of graphene, creating an electric\nfield inside the nanopore. How the water molecules are structured under this\ntype of electrical confinement is studied with two force fields of water, the\nthree-site water models here used are the SCP/$\\epsilon$ and the\nFAB/$\\epsilon$, the first is a rigid model that improves the SPC model and the\nsecond is a flexible model that improves all the force fields of three sites\nnon-polarizables and flexibles."
    },
    {
        "anchor": "Maximum in density heterogeneities of active swimmers: Suspensions of unicellular microswimmers such as flagellated bacteria or\nmotile algae exhibit spontaneous density heterogeneities at large enough\nconcentrations. Based on the relative location of the biological actuation\nappendages i.e. flagella or cilia) microswimmers' propulsion mechanism can be\nclassified into two categories: (i) pushers, like \\textit{E. coli} bacteria or\nspermatozoa, that generate thrust in their rear, push fluid away from them and\npropel themselves forward; (ii) pullers, like the microalgae\n\\textit{Chlamydomonas reinhardtii}, that have two flagella attached to their\nfront, pull the fluid in and thereby generate thrust in their front. We\nintroduce a novel model for biological microswimmers that creates the flow\nfield of the corresponding microswimmers, and takes into account the shape\nanisotropy of the swimmer's body and stroke-averaged flagella. By employing\nmultiparticle collision dynamics, we directly couple the swimmer's dynamics to\nthe fluid's. We characterize the nonequilibrium phase diagram, as the filling\nfraction and P\\'eclet number are varied, and find density heterogeneities in\nthe distribution of both pullers and pushers, due to hydrodynamic\ninstabilities. We find a maximum degree of clustering at intermediate filling\nfractions and at large P\\'eclet numbers resulting from a competition of\nhydrodynamic and steric interactions between the swimmers. We develop an\nanalytical theory that supports these results. This maximum might represent an\noptimum for the microorganisms' colonization of their environment.",
        "positive": "Entropy-driven enhanced self-diffusion in confined reentrant\n  supernematics: We present a molecular dynamics study of reentrant nematic phases using the\nGay-Berne-Kihara model of a liquid crystal in nanoconfinement. At densities\nabove those characteristic of smectic A phases, reentrant nematic phases form\nthat are characterized by a large value of the nematic order parameter\n$S\\simeq1$. Along the nematic director these \"supernematic\" phases exhibit a\nremarkably high self-diffusivity which exceeds that for ordinary, lower-density\nnematic phases by an order of magnitude. Enhancement of self-diffusivity is\nattributed to a decrease of rotational configurational entropy in confinement.\nRecent developments in the pulsed field gradient NMR technique are shown to\nprovide favorable conditions for an experimental confirmation of our\nsimulations."
    },
    {
        "anchor": "Resummed thermodynamic perturbation theory for bond cooperativity in\n  associating fluids: We develop a resummed thermodynamic perturbation theory for bond\ncooperativity in associating fluids by extension of Wertheim's multi - density\nformalism. We specifically consider the case of an associating hard sphere with\ntwo association sites and both pairwise and triplet contributions to the\nenergy. To test the theory we perform new monte carlo simulations. Theory and\nsimulation are found to be in excellent agreement.",
        "positive": "Linear aggregation and liquid-crystalline order: comparison of Monte\n  Carlo simulation and analytic theory: Many soft-matter and biophysical systems are composed of monomers which\nreversibly assemble into rod-like aggregates. The aggregates can then order\ninto liquid-crystal phases if the density is high enough, and liquid-crystal\nordering promotes increased growth of aggregates. Systems that display coupled\naggregation and liquid-crystal ordering include wormlike micelles, chromonic\nliquid crystals, DNA and RNA, and protein polymers and fibrils. Coarse-grained\nmolecular models that capture key features of coupled aggregation and\nliquid-crystal ordering common to many different systems are lacking; in\nparticular, the role of monomer aspect ratio and aggregate flexibility in\ncontrolling the phase behavior are not well understood. Here we study a minimal\nsystem of sticky cylinders using Monte Carlo simulations and analytic theory.\nCylindrical monomers interact primarily by hard-core interactions but can stack\nand bind end to end. We present results for several different cylinder aspect\nratios and a range of end-to-end binding energies. The phase diagrams are\nqualitatively similar to those of chromonic liquid crystals, with an\nisotropic-nematic-columnar triple point. The location of the triple point is\nsensitive to the monomer aspect ratio.We find that the aggregate persistence\nlength varies with temperature in a way that is controlled by the interaction\npotential; this suggests that the form of the interaction potential affects the\nphase behavior of the system. Our analytic theory shows improvement compared to\nprevious theory in quantitatively predicting the I-N transition for relatively\nstiff aggregates, but requires a better treatment of aggregate flexibility."
    },
    {
        "anchor": "Frank-Read Mechanism in Nematic Liquid Crystals: In a crystalline solid under mechanical stress, a Frank-Read source is a\npinned dislocation segment that repeatedly bows and detaches, generating\nconcentric dislocation loops. We demonstrate that in nematic liquid crystals,\nan analogous Frank-Read mechanism can generate concentric disclination loops.\nUsing experiment, simulation, and theory, we study a disclination segment\npinned between surface defects on one substrate in a nematic cell. Under\napplied twist of the nematic director, the pinned segment bows and emits a new\ndisclination loop which expands, leaving the original segment intact; loop\nemission repeats for each additional 180$^\\circ$ of applied twist. We present\nexperimental micrographs showing loop expansion and snap-off, numerical\nsimulations of loop emission under both quasistatic and dynamic loading, and\ntheoretical analysis considering both free energy minimization and the balance\nof competing forces. We find that the critical stress for disclination loop\nemission scales as the inverse of segment length, and changes as a function of\nstrain rate and temperature, in close analogy to the Frank-Read source\nmechanism in crystals. Lastly, we discuss how Frank-Read sources could be used\nto modify microstructural evolution in both passive and active nematics.",
        "positive": "Self-limited self-assembly of chiral filaments: The assembly of filamentous bundles with controlled diameters is common in\nbiological systems and desirable for the development of nanomaterials. We\ndiscuss dynamical simulations and free energy calculations on patchy spheres\nwith chiral pair interactions that spontaneously assemble into filamentous\nbundles. The chirality frustrates long-range crystal order by introducing twist\nbetween interacting subunits. For some ranges of system parameters this\nconstraint leads to bundles with a finite diameter as the equilibrium state,\nand in other cases frustration is relieved by the formation of defects. While\nsome self-limited structures can be modeled as twisted filaments arranged with\nlocal hexagonal symmetry, other structures are surprising in their complexity."
    },
    {
        "anchor": "Inter-dependence of the volume and stress ensembles and equipartition in\n  statistical mechanics of granular systems: We discuss the statistical mechanics of granular matter and derive several\nsignificant results. First, we show that, contrary to common belief, the volume\nand stress ensembles are inter-dependent, necessitating the use of both. We use\nthe combined ensemble to calculate explicitly expectation values of structural\nand stress-related quantities for two-dimensional systems. We thence\ndemonstrate that structural properties may depend on the angoricity tensor and\nthat stress-based quantities may depend on the compactivity. This calls into\nquestion previous statistical mechanical analyses of static granular systems\nand related derivations of expectation values. Second, we establish the\nexistence of an intriguing equipartition principle - the total volume is shared\nequally amongst both structural and stress-related degrees of freedom. Third,\nwe derive an expression for the compactivity that makes it possible to quantify\nit from macroscopic measurements.",
        "positive": "Optical extinction, refractive index, and multiple scattering for\n  suspensions of interacting colloidal particles: We provide a general microscopic theory of the scattering cross-section and\nof the refractive index for a system of interacting colloidal particles, exact\nat second order in the molecular polarizabilities. In particular: a) we show\nthat the structural features of the suspension are encoded into the forward\nscattered field by multiple scattering effects, whose contribution is essential\nfor the so-called \"optical theorem\" to hold in the presence of interactions; b)\nwe investigate the role of radiation reaction on light extinction; c) we\ndiscuss our results in the framework of effective medium theories, presenting a\ngeneral result for the effective refractive index valid, whatever the\nstructural properties of the suspension, in the limit of particles much larger\nthan the wavelength; d) by discussing strongly-interacting suspensions, we\nunravel subtle anomalous dispersion effects for the suspension refractive\nindex."
    },
    {
        "anchor": "Comment on \"Anomalous Discontinuity at the Percolation Critical Point of\n  Active Gels\": In their recent work Sheinman et al. [Phys. Rev. Lett. 114, 098104 (2015)]\nintroduce a variation of percolation which they call no-enclaves percolation\n(NEP). The main claims are 1) the salient physics captured in NEP is closer to\nwhat happens experimentally; 2) The Fisher exponent of NEP, is $\\tau=1.82(1)$;\n3) Due to the different Fisher exponent, NEP constitutes a universality class\ndistinct from random percolation (RP). While we fully agree with 1) and found\nNEP to be a very interesting variation of random percolation, we disagree with\n2) and 3). We will demonstrate that $\\tau$ is exactly $2$, directly derivable\nfrom RP, and thus there is no foundation of a new universality class.",
        "positive": "Testing the variants of the Stokes-Einstein relation in the framework of\n  self-consistent generalized Langevin equation theory: The two functional forms, D~1/tau and D~T/tau, are usually adopted as the\nvariants of the Stokes-Einstein relation; where D is the diffusion constant,\ntau the relaxation time and T the temperature. The self-consistent generalized\nLangevin equation (SCGLE) theory is presented as an analytical tool to predict\nthe long time dynamics of colloids and molecular liquids. In this work, taking\ntruncated Lennard-Jones-like liquids as an example, the rationality of the two\nvariants were tested in the framework of the SCGLE theory. Our results indicate\nthat D~1/tau is a good variant of the Stokes-Einstein relation in the framework\nof SCGLE theory; however, D~T/tau is not a good one but taking a fractional\nfrom as D~(T/tau)^zeta with an exponent zeta is not equal to 1.0 even the\nStokes-Einstein relation is established in SCGLE theory."
    },
    {
        "anchor": "Structure and dynamics of colloidal depletion gels: coincidence of\n  transitions and heterogeneity: Transitions in structural heterogeneity of colloidal depletion gels formed\nthrough short-range attractive interactions are correlated with their dynamical\narrest. The system is a density and refractive index matched suspension of 0.20\nvolume fraction poly(methyl methacyrlate) colloids with the non-adsorbing\ndepletant polystyrene added at a size ratio of depletant to colloid of 0.043.\nAs the strength of the short-range attractive interaction is increased,\nclusters become increasingly structurally heterogeneous, as characterized by\nnumber-density fluctuations, and dynamically immobilized, as characterized by\nthe single-particle mean-squared displacement. The number of free colloids in\nthe suspension also progressively declines. As an immobile cluster to gel\ntransition is traversed, structural heterogeneity abruptly decreases.\nSimultaneously, the mean single-particle dynamics saturates at a localization\nlength on the order of the short-range attractive potential range. Both\nimmobile cluster and gel regimes show dynamical heterogeneity. Non-Gaussian\ndistributions of single particle displacements reveal enhanced populations of\ndynamical trajectories localized on two different length scales. Similar\ndependencies of number density fluctuations, free particle number and dynamical\nlength scales on the order of the range of short-range attraction suggests a\ncollective structural origin of dynamic heterogeneity in colloidal gels.",
        "positive": "Stability and bifurcation of a soap film spanning an elastic loop: The Euler--Plateau problem, proposed by \\cite{gm}, concerns a soap film\nspanning a flexible loop. The shapes of the film and the loop are determined by\nthe interactions between the two components. In the present work, the\nEuler--Plateau problem is reformulated to yield a boundary-value problem for a\nvector field that parameterizes both the spanning surface and the bounding\nloop. Using the first and second variations of the relevant free-energy\nfunctional, detailed bifurcation and stability analyses are performed. For\nspanning surface with energy density $\\sigma$ and a bounding loop with length\n$2\\pi R$ and bending rigidity $a$, the first bifurcation, during which the\nspanning surface remains flat but the bounding loop becomes noncircular, occurs\nat $\\sigma R^3/a=3$, confirming a result obtained previously via an energy\ncomparison. Other bifurcation solution branches, including those emanating from\nthe flat circular solution branch to nonplanar solution branches, are also\nshown to be unstable."
    },
    {
        "anchor": "Interfacial instability and DNA fork reversal by repair proteins: A repair protein like RecG moves the stalled replication fork in the\ndirection from the zipped to the unzipped state of DNA. It is proposed here\nthat a softening of the zipped-unzipped interface at the fork results in the\nfront propagating towards the unzipped side. In this scenario, an ordinary\nhelicase destabilizes the zipped state locally near the interface and the fork\npropagates towards the zipped side. The softening of the interface can be\nproduced by the aromatic interaction, predicted from crystal structure, between\nRecG and the nascent broken base pairs at the Y-fork. A numerical analysis of\nthe model also reveals the possibility of a stop and go type motion.",
        "positive": "Qualitative chirality effects on the Casimir-Lifshitz torque with liquid\n  crystals: We model a cholesteric liquid crystal as a planar uniaxial multilayer system,\nwhere the orientation of each layer differs slightly from that of the adjacent\none. This allows us to analytically simplify the otherwise acutely complicated\ncalculation of the Casimir-Lifshitz torque. Numerical results differ\nappreciably from the case of nematic liquid crystals, which can be treated like\nbloc birefringent media. In particular, we find that the torque deviates\nconsiderably from its usual sinusoidal behavior as a function of the\nmisalignment angle. In the case of a birefringent crystal faced with a\ncholesteric liquid one, the Casimir-Lifshitz torque decreases more slowly as a\nfunction of distance than in the nematic case. In the case of two cholesteric\nliquid crystals, either in the homochiral or in the heterochiral configuration,\nthe angular dependence changes qualitatively as a function of distance. In all\nconsidered cases, finite pitch length effects are most pronounced at distances\nof about 10 nm."
    },
    {
        "anchor": "Geometry-Topology Duality in complex porous networks: We explore the experimental observation that complex networks of porous media\nexhibit the property that the porous coordination number is proportional to its\nsize. Based in this geometry-topology duality we developed an analytical\napproach to describe the permeability transport property of the material. That\nresults was compared with 2D networks simulations. And we found a correlation\ncoefficient greater than 95%.",
        "positive": "Computational studies on the behaviour of anionic and nonionic\n  surfactants at the SiO$_{2}$ (silicon dioxide)/water interface: Molecular dynamics simulations to study the behaviour of anionic (Sodium\nDodecylsulfate, SDS) and nonionic (Monooleate of Sorbitan, SPAN80) surfactants\nclose to a SiO$_{2}$ (silicon dioxide) surface were carried out. Simulations\nshowed that a water layer was first adsorbed on the surface and then the\nsurfactants were attached on that layer. Moreover, it was observed that water\nbehaviour close to the surface influenced the surfactant adsorption since a\nsemi-spherical micelle was formed on the SiO$_{2}$ surface with SDS molecules\nwhereas a cylindrical micelle was formed with SPAN80 molecules. Adsorption of\nthe micelles was conducted in terms of structural properties (density profiles\nand angular distributions) and dynamical behaviour (diffusion coefficients) of\nthe systems. Finally, it was also shown that some water molecules moved inside\nthe solid surface and located at specific sites of the solid surface."
    },
    {
        "anchor": "Statistical description of co-nonsolvency suppression at high pressures: We present an application of Flory-type self-consistent field theory of the\nflexible polymer chain dissolved in the binary mixture of solvents to\ntheoretical description of co-nonsolvency. We show that our theoretical\npredictions are in good quantitative agreement with the recently published MD\nsimulation results for the conformational behavior of a Lennard-Jones flexible\nchain in a binary mixture of the Lennard-Jones fluids. We show that our theory\nis able to describe co-nonsolvency suppression through pressure enhancement to\nextremely high values recently discovered in experiment and reproduced by full\natomistic MD simulations. Analysing a co-solvent concentration in internal\npolymer volume at different pressure values, we speculate that this phenomenon\nis caused by the suppression of the co-solvent preferential solvation of the\npolymer backbone at rather high pressure imposed. We show that when the\nco-solvent-induced coil-globule transition takes place, the entropy and the\nenthalpy contributions to the solvation free energy abruptly decrease, while\nthe solvation free energy remains continuous.",
        "positive": "Yield stress and elasticity influence on surface tension measurements: We have performed surface tension measurements on carbopol gels of different\nconcentrations and yield stresses. Our setup, based on the force exerted by a\ncapillary bridge on two parallel plates, allows to measure an effective surface\ntension of the complex fluid and to investigate the influence of flow history.\nMore precisely the effective surface tension measured after stretching the\nbridge is always higher than after compressing it. The difference between the\ntwo values is due to the existence of a yield stress in the fluid. The\nexperimental observations are successfully reproduced with a simple\nelasto-plastic model. The shape of successive stretching-compression cycles can\nbe described by taking into account the yield stress and the elasticity of the\ngel. We show that the surface tension $\\gamma_{LV}$ of yield stress fluids is\nthe mean of the effective surface tension values only if the elastic modulus is\nhigh compared to the yield stress. This work highlights that thermodynamical\nquantities measurements are challenged by the fluid out-of-equilibrium state\nimplied by jamming, even at small scales where the shape of the bridge is\ndriven by surface energy. Therefore setups allowing deformation in opposite\ndirections are relevant for measurements on yield stress fluids."
    },
    {
        "anchor": "Physical origin of the expansion of polymer coils in a binary solvent in\n  the vicinity of its demixing critical point: Critical fluctuations are known to induce a collapse of polymer chains in a\nmixed solvent upon approaching its liquid-liquid critical point, as originally\npredicted by Brochard and de Gennes. Recently, we have found that closer to the\ncritical point this collapse is followed by a reswelling of the polymer coils\nwell beyond the original dimensions, a phenomenon not predicted by the theory\nof Brochard and de Gennes. We submit that upon approaching the critical\ntemperature more closely, the correlation length of the critical fluctuations\ninside the polymer coils can no longer further increase due to the finite size\nof the coils, resulting in the appearance of large critical Casimir forces that\ncause a significant expansion of the polymer coils. Eventually, micro-phase\nseparation inside the coils will appear and the coils will reshrink. This\nentire process takes place while the bulk solution is still in the one-phase\nregion.",
        "positive": "Probing the glass transition from structural and vibrational properties\n  of zero-temperature glasses: We find that the density dependence of the glass transition temperature of\nLennard-Jones (LJ) and Weeks-Chandler-Andersen (WCA) systems can be predicted\nfrom properties of the zero-temperature ($T=0$) glasses. Below a crossover\ndensity $\\rho_s$, LJ and WCA glasses show different structures, leading to\ndifferent vibrational properties and consequently making LJ glasses more stable\nwith higher glass transition temperatures than WCA ones. Above $\\rho_s$,\nstructural and vibrational quantities of the $T=0$ glasses show scaling\ncollapse. From scaling relations and dimensional analysis, we predict a density\nscaling of the glass transition temperature, in excellent agreement with\nsimulation results. We also propose an empirical expression of the glass\ntransition temperature using structural and vibrational properties of the $T=0$\nglasses, which works well over a wide range of densities."
    },
    {
        "anchor": "Light scattering and phase behavior of Lysozyme-PEG mixtures: Measurements of liquid-liquid phase transition temperatures (cloud points) of\nmixtures of a protein (lysozyme) and a polymer, poly(ethylene glycol) (PEG)\nshow that the addition of low molecular weight PEG stabilizes the mixture\nwhereas high molecular weight PEG was destabilizing. We demonstrate that this\nbehavior is inconsistent with an entropic depletion interaction between\nlysozyme and PEG and suggest that an energetic attraction between lysozyme and\nPEG is responsible. In order to independently characterize the lysozyme/PEG\ninteractions, light scattering experiments on the same mixtures were performed\nto measure second and third virial coefficients. These measurements indicate\nthat PEG induces repulsion between lysozyme molecules, contrary to the\ndepletion prediction. Furthermore, it is shown that third virial terms must be\nincluded in the mixture's free energy in order to qualitatively capture our\ncloud point and light scattering data. The light scattering results were\nconsistent with the cloud point measurements and indicate that attractions do\nexist between lysozyme and PEG.",
        "positive": "Colloidal liquids of yolk-shell particles: In this paper we develop statistical mechanical tools to describe the\nintermediate- and long-time collective- and self-diffusion properties of a\nliquid of strongly-interacting hollow spherical particles (shells), each\nbearing a smaller solid sphere (yolk) in its interior. To decouple two complex\neffects we assume that the hydrodynamic interactions can be accounted for\nthrough the effective short-time self-diffusion coefficients $D^0_s$ and\n$D^0_y$ that describe the short-time Brownian motion of the yolk and the shell\nparticles, and develop a self-consistent generalized Langevin equation theory\nto describe the intermediate- and long-time effects of the direct shell-shell,\nyolk-shell and yolk-yolk interactions. In a concrete application, we consider\nthe simplest yolk-shell model system involving purely repulsive hard-body\ninteractions between all (shell and yolk) particles. Using a softened version\nof these interparticle potentials we perform Brownian dynamics simulations to\ndetermine the mean squared displacement of both types of particles, as well as\nthe intermediate scattering function of the yolk-shell complex. We compare the\ntheoretical and simulation results between them, and with the results for the\nsame system in the absence of yolks. We find that the yolks, which have no\neffect on the shell-shell static structure, influences the dynamic properties\nin a predictable manner, fully captured by the theory."
    },
    {
        "anchor": "On the structure of the Nx phase of symmetric dimers: NMR measurements on a selectively deuteriated liquid crystal dimer CB-C9-CB\nexhibiting two nematic phases show that the molecules in the lower temperature\nnematic phase, Nx, experience a chiral environment and are ordered about a\nunique direction. The results are contrasted with previous reports that\nproposed a twist-bend spatial variation of the director. A structural model is\nproposed wherein the molecules show organization into highly correlated\nassemblies of opposite chirality.",
        "positive": "Stability of Monomer-Dimer Piles: We measure how strong, localized contact adhesion between grains affects the\nmaximum static critical angle, theta_c, of a dry sand pile. By mixing dimer\ngrains, each consisting of two spheres that have been rigidly bonded together,\nwith simple spherical monomer grains, we create sandpiles that contain strong\nlocalized adhesion between a given particle and at most one of its neighbors.\nWe find that tan(theta_c) increases from 0.45 to 1.1 and the grain packing\nfraction, Phi, decreases from 0.58 to 0.52 as we increase the relative number\nfraction of dimer particles in the pile, nu_d, from 0 to 1. We attribute the\nincrease in tan(theta_c(nu_d)) to the enhanced stability of dimers on the\nsurface, which reduces the density of monomers that need to be accomodated in\nthe most stable surface traps. A full characterization and geometrical\nstability analysis of surface traps provides a good quantitative agreement\nbetween experiment and theory over a wide range of nu_d, without any fitting\nparameters."
    },
    {
        "anchor": "Spinodals with Disorder: from Avalanches in Random Magnets to Glassy\n  Dynamics: We revisit the phenomenon of spinodals in the presence of quenched disorder\nand develop a complete theory for it. We focus on the spinodal of an Ising\nmodel in a quenched random field (RFIM), which has applications in many areas\nfrom materials to social science. By working at zero temperature in the\nquasi-statically driven RFIM, thermal fluctuations are eliminated and one can\ngive a rigorous content to the notion of spinodal. We show that the latter is\ndue to the depinning and the subsequent expansion of rare droplets. We work out\nthe associated critical behavior, which, in any finite dimension, is very\ndifferent from the mean-field one: the characteristic length diverges\nexponentially and the thermodynamic quantities display very mild\nnonanalyticities much like in a Griffith phenomenon. From the recently\nestablished connection between the spinodal of the RFIM and glassy dynamics,\nour results also allow us to conclusively assess the physical content and the\nstatus of the dynamical transition predicted by the mean-field theory of\nglass-forming liquids.",
        "positive": "Direct Visualization of Dislocation Dynamics in Grain Boundary Scars: Mesoscale objects with unusual structural features may serve as the analogues\nof atoms in the design of larger-scale materials with novel optical, electronic\nor mechanical behaviour. In this paper we investigate the structural features\nand the equilibrium dynamics of micron-scale spherical crystals formed by\npolystyrene particles adsorbed on the surface of a spherical water droplet. The\nground state of sufficiently large crystals possesses finite-length grain\nboundaries (scars). We determine the elastic response of the crystal by\nmeasuring single-particle diffusion and quantify the fluctuations of individual\ndislocations about their equilibrium positions within a scar determining the\ndislocation spring constants. We observe rapid dislocation glide with\nfluctuations over the barriers separating one local Peierls minimum from the\nnext and rather weak binding of dislocations to their associated scars. The\nlong-distance (renormalised) dislocation diffusion glide constant is extracted\ndirectly from the experimental data and is found to be moderately faster than\nsingle particle diffusion. We are also able to determine the parameters of the\nPeierls potential induced by the underlying crystalline lattice."
    },
    {
        "anchor": "Network-based membrane filters: Influence of network and pore size\n  variability on filtration performance: We model porous membrane filters as networks of connected cylindrical pores\nvia a random network generation protocol, and their initial pore radii via a\nuniform distribution of widths that vary about some mean value. We investigate\nthe influence of network and pore size (radius) variations on the performance\nof membrane filters that undergo adsorptive fouling. We find that membrane\nporosity variations, independently of whether induced by variations of the pore\nradii or of the random pore network, are an important factor determining\nmembrane filter performance. Network and pore size variations still play a\nrole, in particular if pore radii variations are significant. To quantify the\ninfluence of these variations, we compare the performance metrics of networks\nbuilt from pores of variable radii to their (equal porosity) counterparts built\nfrom pores of uniform radius. We show that the effect of pore radii variations\nis to increase throughput, but also to reduce foulant control.",
        "positive": "Heaping, Secondary Flows and Broken Symmetry in Flows of Elongated\n  Granular Particles: In this paper we report experiments where we shear granular rods in\nsplit-bottom geometries, and find that a significant heap of height of least\n40% of the filling height can form at the particle surface. We show that\nheaping is caused by a significant secondary flow, absent for spherical\nparticles. Flow reversal transiently reverses the secondary flow, leading to a\nquick collapse and slower regeneration of the heap. We present a symmetry\nargument and experimental data that show that the generation of the secondary\nflow is driven by a misalignment of the mean particle orientation with the\nstreamlines of the flow. This general mechanism is expected to be important in\nall flows of sufficiently anisometric grains."
    },
    {
        "anchor": "An analytical approach to sorting in periodic potentials: There has been a recent revolution in the ability to manipulate\nmicrometer-sized objects on surfaces patterned by traps or obstacles of\ncontrollable configurations and shapes. One application of this technology is\nto separate particles driven across such a surface by an external force\naccording to some particle characteristic such as size or index of refraction.\nThe surface features cause the trajectories of particles driven across the\nsurface to deviate from the direction of the force by an amount that depends on\nthe particular characteristic, thus leading to sorting. While models of this\nbehavior have provided a good understanding of these observations, the\nsolutions have so far been primarily numerical. In this paper we provide\nanalytic predictions for the dependence of the angle between the direction of\nmotion and the external force on a number of model parameters for periodic as\nwell as random surfaces. We test these predictions against exact numerical\nsimulations.",
        "positive": "Template-Free Preparation of Thermoresponsive Mag-netic Cilia Compatible\n  with Biological Conditions: Bio-inspired materials are commonly used in the development of functional\ndevices. The fabrication of artificial cilia mimicking the biological functions\nhas emerged as a promising strategy for fluid manipulation in miniaturized\nsystems. In this study, we propose a different physicochemical insight for the\npreparation of magnetic cilia based on the temperature-triggered reversible\nassembly of coated iron oxide nanoparticles in a bio-compatible template-free\napproach. The length of the prepared cilia could be tuned between 10 and 100\nmicrons reaching aspect ratios up to 100 in a very dense array of flexible\nstructures with persistence lengths around 8 microns. Magnetic actuation of the\ncilia revealed robust structures (over several hours of actuation) with a wide\nrange of bending amplitudes resulting from high susceptibility of the\nfilaments. The results demonstrate that the proposed strategy is an efficient\nand versatile alternative for templated fabrication methods and producing cilia\nwith remarkable characteristics and dimensions within the template-free\napproaches."
    },
    {
        "anchor": "Dynamical clustering and phase separation in suspensions of\n  self-propelled colloidal particles: We study experimentally and numerically a (quasi) two dimensional colloidal\nsuspension of self-propelled spherical particles. The particles are\ncarbon-coated Janus particles, which are propelled due to diffusiophoresis in a\nnear-critical water-lutidine mixture. At low densities, we find that the\ndriving stabilizes small clusters. At higher densities, the suspension\nundergoes a phase separation into large clusters and a dilute gas phase. The\nsame qualitative behavior is observed in simulations of a minimal model for\nrepulsive self-propelled particles lacking any alignment interactions. The\nobserved behavior is rationalized in terms of a dynamical instability due to\nthe self-trapping of self-propelled particles.",
        "positive": "Morphologies of compressed active epithelial monolayers: Using a three-dimensional active vertex model, we numerically study the\nshapes of strained unsupported epithelial monolayers subject to active\njunctional noise due to stochastic binding and unbinding of myosin. We find\nthat while uniaxial, biaxial, and isotropic in-plane compressive strains do\nlead to the formation of longitudinal, herringbone-pattern, and labyrinthine\nfolds, respectively, the villus morphology characteristic of, e.g., the small\nintestine appears only if junctional tension fluctuations are strong enough to\nfluidize the tissue. Moreover, the fluidized epithelium features villi even in\nabsence of compressive strain provided that the apico-basal differential\ntension is large enough. We analyze several details of the different epithelial\nforms including the role of strain rate and the modulation of tissue thickness\nacross folds. Our results show that nontrivial morphologies can form even in\nunsupported, non-patterned epithelia."
    },
    {
        "anchor": "Independent characterization of the elastic and the mixing parts of\n  hydrogel osmotic pressure: Osmotic pressure is the driving force for the swelling of hydrogels. The\nhydrogel osmotic pressure can be decomposed into two parts: the mixing part due\nto polymer-solvent interaction and the elastic part due to polymer chain\nstretching. While the two components are distinguished in existing constitutive\nmodels, they have not been independently characterized in experiments. This\npaper reports a novel method to independently measure these two components\nusing a fully constrained swelling test. The test allows the crosslink density\nto be varied at a fixed polymer content, thus varying the elastic part\nindependently of the mixing part. Our measurement shows that the widely used\nFlory-Rehner model predicts the mixing part accurately for polyacrylamide\nhydrogel of a wide range of swelling ratios but predicts the elastic part with\norders-of-magnitude error.",
        "positive": "An Itinerant Oscillator model with cage inertia for mesorheological\n  granular experiments: Recent experiments with a rotating probe immersed in weakly fluidized\ngranular materials show a complex behavior on a wide range of timescales.\nViscous-like relaxation at high frequency is accom- panied by an almost\nharmonic dynamical trapping at intermediate times, with possibly anomalous long\ntime behavior in the form of super-diffusion. Inspired by the Itinerant\nOscillator model for dif- fusion in molecular liquids, and other models with\ncoupled thermostats acting at different timescales, here we discuss a new model\nable to account for fast viscous relaxation, dynamical trapping and\nsuper-diffusion at long times. The main difference with respect to liquids, is\na non-negligible cage inertia for the surrounding (granular) fluid, which\nallows it to sustain a slow but persistent mo- tion for long times. The\ncomputed velocity power density spectra and mean-squared displacement\nqualitatively reproduce the experimental findings. We also discuss the linear\nresponse to external perturbations and the tail of the distribution of\npersistency time, which is associated with superdif- fusion, and whose cut-off\ntime is determined by cage inertia."
    },
    {
        "anchor": "Inhomogeneous activity enhances density phase separation in active model\n  B: We study the binary phase separation in active model B, on a two-dimensional\nsubstrate with inhomogeneous activity. The activity was introduced with a\nmaximum value at the center of the box and spread as a Bivariate-Gaussian\ndistribution as we move away from the center. The system was studied for three\ndifferent intensities of the distribution. Towards the boundary of the box,\nactivity is zero or the model is similar to the passive model B. We start from\nthe random homogeneous distribution of density of particles, and the system\nevolves towards a structured distribution of density. With time, density starts\nto phase separately with maximum density at the center of the box and decreases\nas we move away from the center of the box. The width of the density profile at\nthe center increases as a power lawexponent{\\alpha}(t) remains close between\n2/3 to 3/4 up to some moderate time and then decays to zero in the steady\nstate. Hence, our result shows the response of density in an active binary\nsystem with respect to the patterned substrate. It can be used to design\ndevices useful for the trapping and segregation of active particles.",
        "positive": "Structure, Dynamics and Hydrogen Transport in Amorphous Polymers: An\n  Analysis of the Interplay Between Free Volume Element Distribution and Local\n  Segmental Dynamics from Molecular Dynamics Simulations: An important indicator of membrane performance are free volume elements\n(FVEs): microporous void spaces created by the inefficient packing of bulky\ngroups along the polymer chain. FVEs tend to degrade over time as polymer\nchains reorganize irreversibly. While it is widely accepted that polymer\nflexibility has an impact on membrane transport properties, the molecular\nnature of this impact is still not well-understood. By establishing a\ncorrelation between local chain dynamics and the distribution of free volume\nelements (FVEs), penetrant transport can be regulated more efficiently in\namorphous polymer membranes. In this work, we implement all-atom molecular\ndynamics (MD) simulations to explore the relationship between chain dynamics\nand free volume in three polymers with different levels of backbone\nflexibility: polymethylpentene (PMP), polystyrene (PS), and HAB-6FDA thermally\nrearranged polymer (TRP). We construct these polymers at different temperatures\nand examine how temperature impacts the FVE distribution and segmental\nmobility. Our analysis shows that chain segments near FVEs have higher mobility\ncompared to the atoms in the bulk; the extent of this difference increases with\nchain flexibility. Increasing chain flexibility by increasing the temperature\nresults in a broader FVE distribution. Rigid polymers such as TRP show the most\nrobust FVE distribution and are not significantly affected by temperature\nchange. To capture penetrant diffusion through the polymer matrix, hydrogen is\ninserted, and the diffusion is measured at different temperatures; hydrogen\nmobility is influenced by the FVE structure and overall mobility of polymer\nchains. At low temperatures, hydrogen mobility is influenced by void\ndistribution, while at high temperatures, polymer dynamics dictates hydrogen\ntransport."
    },
    {
        "anchor": "Interplay between wall slip and shear banding in a thixotropic yield\n  stress fluid: We study the local dynamics of a thixotropic yield stress fluid that shows a\npronounced non-monotonic flow curve. This mechanically unstable behavior is\ngenerally not observable from standard rheometry tests, resulting in a stress\nplateau that stems from the coexistence of a flowing band with an unyielded\nregion below a critical shear rate $\\dot \\gamma_c$. Combining ultrasound\nvelocimetry with standard rheometry, we discover an original shear-banding\nscenario in the decreasing branch of the flow curve of model paraffin gels, in\nwhich the flow profile of the flowing band is set by the applied shear rate\n$\\gd$ instead of $\\dot \\gamma_c$. As a consequence, the material slips at the\nwalls with a velocity that shows a non-trivial dependence on the applied shear\nrate. To capture our observations, we propose a differential version of the\nso-called lever rule, describing the extent of the flowing band and the\nevolution of wall slip with shear rate. This phenomenological model holds down\nto very low shear rates, at which the dimension of the flowing band becomes\ncomparable to the size of the wax particles that constitute the gel\nmicrostructure, leading to cooperative effects. Our approach provides a\nframework where constraints imposed in the classical shear-banding scenario can\nbe relaxed, with wall slip acting as an additional degree of freedom.",
        "positive": "Packing frustration in dense confined fluids: Packing frustration for confined fluids, i.e., the incompatibility between\nthe preferred packing of the fluid particles and the packing constraints\nimposed by the confining surfaces, is studied for a dense hard-sphere fluid\nconfined between planar hard surfaces at short separations. The detailed\nmechanism for the frustration is investigated via an analysis of the\nanisotropic pair distributions of the confined fluid, as obtained from integral\nequation theory for inhomogeneous fluids at pair correlation level within the\nanisotropic Percus-Yevick approximation. By examining the mean forces that\narise from interparticle collisions around the periphery of each particle in\nthe slit, we calculate the principal components of the mean force for the\ndensity profile - each component being the sum of collisional forces on a\nparticle's hemisphere facing either surface. The variations of these components\nwith the slit width give rise to rather intricate changes in the layer\nstructure between the surfaces, but, as shown in this paper, the basis of these\nvariations can be easily understood qualitatively and often also\nsemi-quantitatively. It is found that the ordering of the fluid is in essence\ngoverned locally by the packing constraints at each single solid-fluid\ninterface. A simple superposition of forces due to the presence of each surface\ngives surprisingly good estimates of the density profiles, but there remain\nnontrivial confinement effects that cannot be explained by superposition, most\nnotably the magnitude of the excess adsorption of particles in the slit\nrelative to bulk."
    },
    {
        "anchor": "Capillary imbibition in a square tube: When a square tube is brought in contact with bulk liquid, the liquid wets\nthe corners of the tube, and creates finger-like wetted region. The wetting of\nthe liquid then takes place with the growth of two parts, the bulk part where\nthe cross section is entirely filled with the liquid and the finger part where\nthe cross section of the tube is partially filled. In the previous works, the\ngrowth of these two parts has been discussed separately. Here we conduct the\nanalysis by explicitly accounting for the coupling of the two parts. We propose\ncoupled equations for the liquid imbibition in both parts and show that (a) the\nlength of each part, $h_0$ and $h_1$, both increases in time $t$ following the\nLucas-Washburn's law, $h_0 \\sim t^{1/2}$ and $h_1 \\sim t^{1/2}$, but that (b)\nthe coefficients are different from those obtained in the previous analysis\nwhich ignored the coupling.",
        "positive": "Analytical approach to chiral active systems: suppressed phase\n  separation of interacting Brownian circle swimmers: We consider chirality in active systems by exemplarily studying the phase\nbehavior of planar systems of interacting Brownian circle swimmers with a\nspherical shape. Continuing previous work presented in [G.-J. Liao, S. H. L.\nKlapp, Soft Matter, 2018, 14, 7873-7882], we derive a predictive field theory\nthat is able to describe the collective dynamics of circle swimmers. The theory\nyields a mapping between circle swimmers and noncircling active Brownian\nparticles and predicts that the angular propulsion of the particles leads to a\nsuppression of their motility-induced phase separation, being in line with\nprevious simulation results. In addition, the theory provides analytical\nexpressions for the spinodal corresponding to the onset of motility-induced\nphase separation and the associated critical point as well as for their\ndependence on the angular propulsion of the circle swimmers. We confirm our\nfindings by Brownian dynamics simulations and an analysis of the collective\ndynamics using a weighted graph-theoretical network. The agreement between\nresults from theory and simulation is found to be good."
    },
    {
        "anchor": "Ultra-low effective interfacial tension between miscible molecular\n  fluids: We exploit the deformation of drops spinning in a denser background fluid to\ninvestigate the effective interfacial tension (EIT) between miscible molecular\nfluids. We find that for sufficiently low interfacial tension, spinning drops\ndevelop dumbbell shapes, with two large heads connected by a thinner central\nbody. We show that this shape depends not only on the density and viscosity\ncontrast between the drop and background fluids, but also on the fluid\nmolecular structure, and hence on the stresses developing at their interface\ndue to different molecular interaction. We systematically investigate the\ndynamics of dumbbell-shaped drops of water-glycerol mixtures spinning in a pure\nglycerol reservoir. By developing a model for the deformation based on the\nbalance of the shear stress opposing the deformation, the imposed normal stress\non the drop and an effective interfacial tension, we exploit the time evolution\nof the drop shape to measure the EIT. Our results show that the EIT in\nwater-glycerol systems is orders of magnitude lower than that reported in\nprevious experimental measurements, and in excellent agreement with values\ncalculated via the phase field model proposed in [Phys. Rev. X 6, 041057,\n2016].",
        "positive": "Molecular dynamics simulation of behaviour of water in nano-confined\n  ionic liquid--water mixtures: This work describes the behaviour of water molecules in\n1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid under\nnanoconfinement between graphene sheets. By means of molecular dynamics\nsimulations, an adsorption of water molecules at the graphene surface is\nstudied. A depletion of water molecules in the vicinity of the neutral and\nnegatively charged graphene surfaces and their adsorption at the positively\ncharged surface are observed in line with the preferential hydration of the\nionic liquid anions. The findings are appropriately described using a two-level\nstatistical model. The confinement effect on the structure and dynamics of the\nmixtures is thoroughly analyzed using the density and the potential of mean\nforce profiles, as well as by the vibrational densities of states of water\nmolecules near the graphene surface. The orientation of water molecules and the\nwater-induced structural transitions in the layer closest to the graphene\nsurface are also discussed."
    },
    {
        "anchor": "Isotropic-Nematic Transition and Demixing Behaviour in Binary Mixtures\n  of Hard Spheres and Hard Spherocylinders Confined in a Disordered Porous\n  Medium: Scaled Particle Theory: We develop the scaled particle theory to describe the thermodynamic\nproperties and orientation ordering of a binary mixture of hard spheres (HS)\nand hard spherocylinders (HSC) confined in a disordered porous medium. Using\nthis theory the analytical expressions of the free energy, the pressure and the\nchemical potentials of HS and HSC have been derived. The improvement of\nobtained results is considered by introducing the Carnahan-Starling-like and\nParsons-Lee-like corrections. Phase diagrams for the isotropic-nematic\ntransition are calculated from the bifurcation analysis of the integral\nequation for the orientation singlet distribution function and from the\nconditions of thermodynamic equilibrium. Both the approaches correctly predict\nthe isotropic-nematic transition at low concentrations of hard spheres.\nHowever, the thermodynamic approach provides more accurate results and is able\nto describe the demixing phenomena in the isotropic and nematic phases. The\neffects of porous medium on the isotropic-nematic phase transition and demixing\nbehaviour in a binary HS/HSC mixture are discussed.",
        "positive": "Rupture of a liposomal vesicle: We discuss pore dynamics in osmotically stressed vesicles. A set of equations\nwhich govern the liposomal size, internal solute concentration, and pore\ndiameter is solved numerically. We find that dependent on the internal solute\nconcentration and vesicle size, liposomes can stay pore-free, nucleate a short\nlived pore, or nucleate a long-lived pore. The phase diagram of pore stability\nis constructed, and the different scaling regimes are deduced analytically."
    },
    {
        "anchor": "Phase separation and self-assembly in vitrimers: hierarchical morphology\n  of molten and semi-crystalline polyethylene/dioxaborolane maleimide systems: Vitrimers - a class of polymer networks which are covalently crosslinked and\ninsoluble like thermosets, but flow when heated like thermoplastics - contain\ndynamic links and/or crosslinks that undergo an associative exchange reaction.\nThese dynamic crosslinks enable vitrimers to have interesting\nmechanical/rheological behavior, self-healing, adhesive, and shape memory\nproperties. We demonstrate that vitrimers can self-assemble into complex meso-\nand nanostructures when crosslinks and backbone monomers strongly interact.\nVitrimers featuring polyethylene (PE) as the backbone and dioxaborolane\nmaleimide as the crosslinkable moiety were studied in both the molten and\nsemi-crystalline states. We observed that PE vitrimers macroscopically phase\nseparated into dioxaborolane maleimide rich and poor regions, and characterized\nthe extent of phase separation by optical transmission measurements. This phase\nseparation can explain the relatively low insoluble fractions and overall\ncrystallinities of PE vitrimers. Using synchrotron-sourced small-angle X-ray\nscattering (SAXS), we discovered that PE vitrimers and their linear precursors\nmicro-phase separated into hierarchical nanostructures. Fitting of the SAXS\npatterns to a scattering model strongly suggests that the nanostructures -\nwhich persist in both the melt and amorphous fraction of the semi-crystalline\nstate - may be described as dioxaborolane maleimide rich aggregates packed in a\nmass fractal arrangement. These findings of hierarchical meso- and\nnanostructures point out that incompatibility effects between network\ncomponents and resulting self-assembly must be considered for understanding\nbehavior and the rational design of vitrimer materials.",
        "positive": "A smart granular intruder: It has been recently reported that irregular objects sink irregularly when\nreleased in a granular medium: a subtle lack of symmetry in the density or\nshape of a macroscopic object may produce a large tilting and deviation from\nthe vertical path when released from the free surface of a granular bed. This\ncan be inconvenient -- even catastrophic -- in scenarios ranging from buildings\nto space rovers. Here, we take advantage of the high sensitivity of granular\nintruders to shape asymmetry: we introduce a granular intruder equipped with an\ninflatable bladder that protrudes from the intruder's surface as an autonomous\nresponse to an unwanted tilting. So, the intruder's symmetry is only slightly\nmanipulated, resulting in the rectification of the undesired tilting. Our smart\nintruder is even able to rectify its settling path when perturbed by an\nexternal element, like a vertical wall. The general concept introduced here can\nbe potentially expanded to real-life scenarios, such as ``smart foundations''\nto mitigate the inclination of constructions on a partially fluidized soil."
    },
    {
        "anchor": "Lipid Bilayer-Coated Curcumin-based Mesoporous Organosilica\n  Nanoparticles for Cellular Delivery: Effective and controlled drug delivery systems with on-demand release\nabilities and biocompatible properties receive enormous attention for\nbiomedical applications. Here, we describe a novel inorganic-organic hybrid\nmaterial with a strikingly high organic content of almost 50 wt%. The colloidal\nperiodic mesoporous organosilica (PMO) nanoparticles synthesized in this work\nconsist entirely of curcumin and ethane derivatives serving as constituents\nthat are crosslinked by siloxane bridges, without any added silica. These\nmesoporous curcumin nanoparticles (MCNs) exhibit very high surface areas (over\n1000 m2/g), narrow particle size distribution (around 200 nm) and a strikingly\nhigh stability in simulated biological media. Additionally, the MCNs are used\nas a cargo delivery system in live-cell experiments. A supported lipid bilayer\n(SLB) efficiently seals the pores and releases Rhodamin B as model cargo in\nHeLa cells. This novel nanocarrier concept provides a promising platform for\nthe development of controllable and highly biocompatible theranostic systems.",
        "positive": "The Extension of Rod-Coil Multiblock Copolymers and the Effect of the\n  Helix-Coil Transition: The extension elasticity of rod-coil mutliblock copolymers is analyzed for\ntwo experimentally accessible situations. In the quenched case, when the\narchitecture is fixed by the synthesis, the force law is distinguished by a\nsharp change in the slope. In the annealed case, where interconversion between\nrod and coil states is possible, the resulting force law is sigmoid with a\npronounced plateau. This last case is realized, for example, when\nhomopolypeptides capable of undergoing a helix-coil transition are extended\nfrom a coil state. Both scenarios are relevant to the analysis and design of\nexperiments involving single molecule mechanical measurements of biopolymers\nand synthetic macromolecules."
    },
    {
        "anchor": "Structural Transitions in A Crystalline Bilayer : The Case of Lennard\n  Jones and Gaussian Core Models: We study structural transitions in a system of interacting particles arranged\nas a crystalline bilayer, as a function of the density $\\rho$ and the distance\n$d$ between the layers. As $d$ is decreased a sequence of transitions involving\ntriangular, rhombic, square and centered rectangular lattices is observed. The\nsequence of phases and the order of transitions depends on the nature of\ninteractions.",
        "positive": "Athermal fluctuations in three dimensional disordered crystals: We study jammed near-crystalline materials composed of frictionless spheres\nin three dimensions. We analyze the fluctuations in positions and forces\nproduced by small polydispersity in particle sizes. We generalize a recently\ndeveloped perturbation expansion about the crystalline ordered state to three\ndimensional systems. This allows us to exactly predict changes in positions and\nforces as a response to the changes in particle radii. We show that\nfluctuations in forces orthogonal to the lattice directions are highly\nconstrained as compared to the fluctuations along lattice directions.\nAdditionally, we analyze the correlations in the displacement fields produced\nby the microscopic disorder, which we show displays long ranged behaviour."
    },
    {
        "anchor": "Connection between slow and fast dynamics of molecular liquids around\n  the glass transition: The mean-square displacement (MSD) was measured by neutron scattering at\nvarious temperatures and pressures for a number of molecular glass-forming\nliquids. The MSD is invariant along the glass-transition line at the pressure\nstudied, thus establishing an ``intrinsic'' Lindemann criterion for any given\nliquid. A one-to-one connection between the MSD's temperature dependence and\nthe liquid's fragility is found when the MSD is evaluated on a time scale of\napproximately 4 nanoseconds, but does not hold when the MSD is evaluated at\nshorter times. The findings are discussed in terms of the elastic model and the\nrole of relaxations, and the correlations between slow and fast dynamics are\naddressed.",
        "positive": "Low Dimensional Assemblies of Magnetic MnFe$_2$O$_4$ Nanoparticles and\n  Direct In Vitro Measurements of Enhanced Heating Driven by Dipolar\n  Interactions: Implications for Magnetic Hyperthermia: Magnetic fluid hyperthermia (MFH), the procedure of raising the temperature\nof tumor cells using magnetic nanoparticles (MNPs) as heating agents, has\nproven successful in treating some types of cancer. However, the low heating\npower generated under physiological conditions makes necessary a high local\nconcentration of MNPs at tumor sites. Here, we report how the in vitro heating\npower of magnetically soft MnFe$_2$O$_4$ nanoparticles can be enhanced by\nintracellular low-dimensional clusters through a strategy that includes: a) the\ndesign of the MNPs to retain N\\'eel magnetic relaxation in high viscosity\nmedia, and b) culturing MNP-loaded cells under magnetic fields to produce\nelongated intracellular agglomerates. Our direct in vitro measurements\ndemonstrated that the specific loss power (SLP) of elongated agglomerates\n($SLP=576\\pm33$ W/g) induced by culturing BV2 cells in situ under a dc magnetic\nfield was increased by a factor of 2 compared to the $SLP=305\\pm25$ W/g\nmeasured in aggregates freely formed within cells. A numerical mean-field model\nthat included dipolar interactions quantitatively reproduced the SLPs of these\nclusters both in phantoms and in vitro, suggesting that it captures the\nrelevant mechanisms behind power losses under high-viscosity conditions. These\nresults indicate that in situ assembling of MNPs into low-dimensional\nstructures is a sound possible way to improve the heating performance in MFH."
    },
    {
        "anchor": "Acoustic resonances in a confined set of macroscopic disks: We study in this work a system of granular disks enclosed in a rectangular\nregion. Granular disks are arranged, at high particle density, in a hexagonal\nlattice. Specifically, we are interested in the conditions for mechanical\nsignal transmission. Two different potentials are considered. Our results are\nobtained by means of soft disks computer simulations. We analytically determine\nthe eigenfrequencies spectra of the system from the corresponding Hessian\nmatrix. Alternatively, the eigenfrequencies can also be obtained from the time\nevolution of molecular dynamics simulations. Previous works have shown that\nmechanical signal transmission in granular matter can be used to develop\nacoustic switches. Our results reveal that the working range of the granular\nswitch changes dramatically for different interaction models. In particular,\nstrong anisotropies in signal transmission may appear for certain interparticle\nforces.",
        "positive": "On the swelling properties of pom-pom polymers in dilute solutions. Part\n  1: symmetric case: We consider the simplest representative of the class of multiply branched\npolymer macromolecules, known as a pom-pom structure. The molecule consists of\na backbone linear chain terminated by two branching points with functionalities\n(numbers of side chains) of $f_1$ and $f_2$, respectively. In a symmetrical\ncase, considered in the present study, one has $f_1=f_2=f$ with the total\nnumber of chains $F=2f+1$. Whereas rheological behaviour of melts of pom-pom\nmolecules are intensively studied so far, we turn our attention towards\nconformational properties of such polymers in a regime of dilute solution. The\nuniversality concept, originated in the critical phenomena and in scaling\nproperties of polymers, is used in this study. To be able to compare the\noutcome of the direct polymer renormalization approach with that obtained via\ndissipative particle dynamics simulations, we concentrated on the universal\nratios of the shape characteristics. In this way the differences in the energy\nand length scales are eliminated and the universal ratios depend only on space\ndimension, solvent quality and a type of molecular branching. Such universal\nratios were evaluated both for a whole molecule and for its individual\nbranches. For some shape properties, theory and simulations are in excellent\nagreement, for other we found the interval of $F$ where both agree reasonably\nwell. Combination of theoretical and simulation approaches provide thorough\nquantitative description of the peculiarities of swelling effects and spatial\nextension of pom-pom molecules and are compared with the known results for\nsimpler molecular topologies."
    },
    {
        "anchor": "Can experiments select the configurational component of excess entropy?: We introduce an experimental method of assessing the vibrational and\nconfigurational components of the excess entropy of a liquid over crystal,\nbased on a joined investigation of dynamic and thermodynamic properties as a\nfunction of temperature and pressure. We analyze light scattering, dielectric,\ncalorimetric and dilatometric measurements of three prototype glass formers,\northoterphenyl, salol, and glycerol. In all cases we find that about 70% of the\nexcess entropy is configurational in nature.",
        "positive": "Rebound suppression of a droplet impact on a supersolvophobic surface by\n  a small amount of polymer additives: A small amount of polymer dissolved in a droplet suppresses droplet rebound\nwhen it impinges on a supersolvophobic surface. This work investigates\nimpacting dynamics of a droplet of dilute polymer solution depending on the\nmolecular weight and the concentration of the polymer by using multi-body\ndissipative particle dynamics simulations. Either the longer polymer or the\nhigh polymer concentration suppresses rebound of a droplet although its shear\nviscosity and the liquid-vapor surface tension are not different from those of\na pure solvent droplet. We found a new mechanism of the anti-rebound in which\nthe resistance is applied against the hopping motion, while behavior of the\nnon-rebounding droplet at the earlier spreading and retraction stages is same\nas for the rebounding droplets. Two polymer contributions to reducing the\nrebound tendency are quantitatively analyzed: the alteration of the substrate\nwettability by the polymer adsorption and the polymer elongation force."
    },
    {
        "anchor": "Conflicting Effects of Extreme Nanoconfinement on the Translational and\n  Segmental Motion of Entangled Polymers: Physically confining polymers into nanoscale pores induces significant\nchanges in their dynamics. Although different results on the effect of\nconfinement on the dynamics of polymers have been reported, changes in the\nsegmental mobility of polymers typically are correlated with changes in their\nchain mobility due to increased monomeric relaxation times. In this study, we\nshow that translational and segmental dynamics of polymers confined in\ndisordered packings of nanoparticles can exhibit completely opposite behavior.\nWe monitor the capillary rise dynamics of entangled polystyrene (PS) in\ndisordered packings of silica nanoparticles (NPs) of 7 and 27 nm diameter. The\neffective viscosity of PS in 27 nm $SiO_2$ NP packings, inferred based on the\nLucas-Washburn equation, is significantly smaller than the bulk viscosity, and\nthe extent of reduction in the translational motion due to confinement\nincreases with the molecular weight of PS, reaching 4 orders of magnitude\nreduction for PS with a molecular weight of 4M g/mol. The glass transition\ntemperature of entangled PS in the packings of 27 nm $SiO_2$ NPs, however,\nincreases by 45 K, indicating significant slowdown of segmental motion.\nInterestingly, confinement of the polymers into packings made of 7 nm $SiO_2$\nNPs results in molecular weight-independent effective viscosity. The segmental\ndynamics of PS in 7 nm $SiO_2$ NP packings are slowed down even further as\nevidenced by 65 K increase in glass transition temperature. These seemingly\ndisparate effects are explained by the microscopic reptation-like transport\ncontrolling the translational motion and the physical confinement affecting the\nsegmental dynamics under extreme nanoconfinement.",
        "positive": "Structural relaxation, dynamical arrest and aging in soft-sphere liquids: We investigate the structural relaxation of a soft-sphere liquid quenched\nisochorically ($\\phi=0.7$) and instantaneously to different temperatures $T_f$\nabove and below the glass transition. For this, we combine extensive Brownian\ndynamics simulations and theoretical calculations based on the non-equilibrium\nself-consistent generalized Langevin equation (NE-SCGLE) theory. The response\nof the liquid to a quench generally consists of a sub-linear increase of the\n$\\alpha$-relaxation time with system's age. Approaching the ideal\nglass-transition temperature from above ($T_f>T^a$) sub-aging appears as a\ntransient process describing a broad equilibration crossover for quenches to\nnearly arrested states. This allows us to empirically determine an\nequilibration timescale $t^{eq}(T_f)$ that becomes increasingly longer as $T_f$\napproaches $T^a$. For quenches inside the glass ($T_f\\leq T^a$) the growth rate\nof the structural relaxation time becomes progressively larger as $T_f$\ndecreases and, unlike the equilibration scenario, $\\tau_{\\alpha}$ remains\nevolving within the whole observation time-window.These features are\nconsistently found in theory and simulations with remarkable semi-quantitative\nagreement, and coincide with those revealed in the similar and complementary\nexercise [Phys. Rev. {\\bf 96}, 022608 (2017)] that considered a sequence of\nquenches with fixed final temperature $T_f=0$ but increasing $\\phi$ towards the\nhard-sphere dynamical arrest volume fraction $\\phi^a_{HS}=0.582$. The NE-SCGLE\nanalysis, however, unveils various fundamental aspects of the glass transition,\ninvolving the abrupt passage from the ordinary equilibration scenario to the\npersistent aging effects that are characteristic of glass-forming liquids. The\ntheory also explains that, within the time window of any experimental\nobservation, this can only be observed as a continuous crossover."
    },
    {
        "anchor": "Hydration interactions: aqueous solvent effects in electric double\n  layers: A model for ionic solutions with an attractive short-range pair interaction\nbetween the ions is presented. The short-range interaction is accounted for by\nadding a quadratic non-local term to the Poisson-Boltzmann free energy. The\nmodel is used to study solvent effects in a planar electric double layer. The\ncounter-ion density is found to increase near the charged surface, as compared\nwith the Poisson-Boltzmann theory, and to decrease at larger distances. The ion\ndensity profile is studied analytically in the case where the ion distribution\nnear the plate is dominated only by counter-ions. Further away from the plate\nthe density distribution can be described using a Poisson-Boltzmann theory with\nan effective surface charge that is smaller than the actual one.",
        "positive": "Polymer desorption under pulling: a novel dichotomic phase transition: We show that the structural properties and phase behavior of a self-avoiding\npolymer chain on adhesive substrate, subject to pulling at the chain end, can\nbe obtained by means of a Grand Canonical Ensemble (GCE) approach. We derive\nanalytical expressions for the mean length of the basic structural units of\nadsorbed polymer, such as loops and tails, in terms of the adhesive potential\nand detachment force, and determine values of the universal exponents which\ngovern their probability distributions. Most notably, the hitherto\ncontroversial value of the critical adsorption exponent $\\phi$ is found to\ndepend essentially on the interaction between different loops. The chain\ndetachment transition turns out to be of the first order, albeit dichotomic,\ni.e., no coexistence of different phase states exists. These novel theoretical\npredictions and the suggested phase diagram of the adsorption-desorption\ntransformation under external pulling force are verified by means of extensive\nMonte Carlo simulations."
    },
    {
        "anchor": "Pseudo-Casimir stresses and elasticity of a confined elastomer film: Investigations of the elastic behavior of bulk elastomers have traditionally\nproceeded on the basis of classical rubber elasticity, which regards chains as\nthermally fluctuating but disregards the thermal fluctuations of the\ncross-links. Here, we consider an incompressible and flat elastomer film of an\naxisymmetric shape confined between two large hard co-planar substrates, with\nthe axis of the film perpendicular to the substrates. We address the impact\nthat thermal fluctuations of the cross-links have on the free energy of elastic\ndeformation of the system, subject to the requirement that the fluctuating\nelastomer cannot detach from the substrates. We examine the behavior of the\ndeformation free energy for one case where a rigid pinning boundary condition\nis applied to a class of elastic fluctuations at the confining surfaces, and\nanother case where the same elastic fluctuations are subjected to soft \"gluing\"\npotentials. We find that there can be significant departures (both quantitative\nand qualitative) from the prediction of classical rubber elasticity theory when\nelastic fluctuations are included. Finally, we compare the character of the\nattractive part of the elastic fluctuation-induced, or pseudo-Casimir, stress\nwith the standard thermal Casimir stress in confined but non-elastomeric\nsystems, finding the same power law decay behavior when a rigid pinning\nboundary condition is applied, for the case of the gluing potential, we find\nthat the leading order correction to the attractive part of the fluctuation\nstress decays inversely with the inter-substrate separation.",
        "positive": "Force spectroscopy analysis in polymer translocation: This paper reports the force spectroscopy analysis of a polymer that\ntranslocates from one side of a membrane to the other side through an extended\npore, pulled by a cantilever that moves with constant velocity against the\ndamping and the potential barrier generated by the reaction of the membrane\nwalls. The polymer is modeled as a beads-springs chain with both excluded\nvolume and bending contributions, and moves in a stochastic three dimensional\nenvironment described by a Langevin dynamics at fixed temperature. The force\ntrajectories recorded at different velocities reveal two unexplored exponential\nregimes: the force increases when the first part of the chain enters the pore,\nand then decreases when the first monomer reaches the trans region. The\nspectroscopy analysis of the force values permit the estimation of the free\nenergy barrier as well as the limit force to permit the translocation. The\nstall force to maintain the polymer fixed has been also calculated\nindependently, and its value confirms the force spectroscopy outcomes."
    },
    {
        "anchor": "Nonlinear Strain Theory of Plastic Flow in Solids: We present a phenomenological time-dependent Ginzburg-Landau theory of\nnonlinear plastic deformations in solids. Because the problem is very complex,\nwe first give models in one and two dimensions without vacancies and\ninterstitials, where large strains produce densely distributed slips but the\nmass density deviations remain small except near the tips of slips. Next we set\nup a two-dimensional model including a vacancy field (or local free-volume\nfraction), where relevant is the sensitive dependence of the elastic shear\nmodulus on the vacancy density. In our simulation, if strains are applied to\nnearly defectless solids but in the presence of such elastic inhomogeneity, the\nvacancy density and the mass density can become considerably heterogeneous for\nlarge strains on spatial scales much longer than the atomic size. These\nstrain-induced disordered states are metastable or long-lived once they are\ncreated.",
        "positive": "Short Chains Enhance Slip of Highly Entangled Polystyrenes during Thin\n  Film Dewetting: We investigate the effect of short chains on slip of highly entangled\npolystyrenes (PS) during thin film dewetting from non-wetting fluorinated\nsurfaces. Binary and ternary mixtures were prepared from monodisperse PS with\nweight average molecular weights $5 < M_\\textrm{w} < 490$ kg/mol. Flow dynamics\nand rim morphology of dewetting holes were captured using optical and atomic\nforce microscopy. Slip properties are assessed in the framework of hydrodynamic\nmodels describing the rim height profile of dewetting holes. We show that short\nchains with $M_\\textrm{w}$ below the polymer critical molecular weight for\nentanglements, $M_\\textrm{c}$, can play an important role in slip of highly\nentangled polymers. Among mixtures of the same $M_\\textrm{w}$, those containing\nchains with $M<M_\\textrm{c}$ exhibit larger slip lengths as the number average\nmolecular weight, $M_\\textrm{n}$, decreases. The slip enhancement effect is\nonly applicable when chains with $M<M_\\textrm{c}$ are mixed with highly\nentangled chains such that the content of the long chain component,\n$\\phi_\\textrm{L}$, is dominant ($\\phi_\\textrm{L}<0.5$). These results suggest\nthat short chains affect slip of highly entangled polymers on non-wetting\nsurfaces due to the physical or chemical disparities of end groups, and any\nassociated dynamical effect their presence may have, as compared to the\nbackbone units. The enhanced slip in this regard is attributed to the impact of\nchain end groups or short chain enrichment on the effective interfacial\nfriction coefficient. Accordingly, for entangled PS, a higher concentration of\nend groups or short chains at the interface results in a lower effective\nfriction coefficient which consequently enhances the slip length."
    },
    {
        "anchor": "Monte Carlo Simulation of Dense Polymer Melts Using Event Chain\n  Algorithms: We propose an efficient Monte Carlo algorithm for the off-lattice simulation\nof dense hard sphere polymer melts using cluster moves, called event chains,\nwhich allow for a rejection-free treatment of the excluded volume. Event chains\nalso allow for an efficient preparation of initial configurations in polymer\nmelts. We parallelize the event chain Monte Carlo algorithm to further increase\nsimulation speeds and suggest additional local topology-changing moves (\"swap\"\nmoves) to accelerate equilibration. By comparison with other Monte Carlo and\nmolecular dynamics simulations, we verify that the event chain algorithm\nreproduces the correct equilibrium behavior of polymer chains in the melt. By\ncomparing intrapolymer diffusion time scales, we show that event chain Monte\nCarlo algorithms can achieve simulation speeds comparable to optimized\nmolecular dynamics simulations. The event chain Monte Carlo algorithm exhibits\nRouse dynamics on short time scales. In the absence of swap moves, we find\nreptation dynamics on intermediate time scales for long chains.",
        "positive": "Microtube self-assembly leads to conformational freezing point\n  depression: Concentric microtubes of $\\beta$-cyclodextrin and SDS grow from the outside\nin and melt from the inside out, we observe using in situ small angle X-ray\nscattering. We find that the conformation of the crystalline bilayer affects\nthe saturation concentration, providing an example of a phenomenon we call\nconformational freezing point depression. We propose a model based on freezing\npoint depression, well known from undergraduate physics, and use it to explain\nthe energetics of this hierarchical system, and giving access to material\nproperties without free parameters."
    },
    {
        "anchor": "Intramolecular and water mediated tautomerism of solvated glycine: The understanding of prototropic tautomerism in water and the\ncharacterization of solvent effects on protomeric equilibrium pose significant\nchallenges. Using molecular dynamics simulations based on state-of-the-art deep\nlearning potential and enhanced sampling methods, we provide a comprehensive\ndescription of all configurational transformations in glycine solvated in water\nand determine accurate free energy profiles of these processes. We observe that\nthe tautomerism between the neutral and zwitterionic forms of solvated glycine\ncan occur by both intramolecular proton transfer in glycine and intermolecular\nproton transfer in the contact ion pair (anionic glycine and hydronium ion) or\nthe separated ion pair (cationic glycine and hydroxide ion).",
        "positive": "The effect of inter-cluster interactions on the structure of colloidal\n  clusters: Colloidal systems present exciting opportunities to study clusters. Unlike\natomic clusters, which are frequently produced at extremely low density,\ncolloidal clusters may interact with one another. Here we consider the effect\nof such interactions on the intra-cluster structure in simulations of colloidal\ncluster fluids. A sufficient increase in density leads to a higher population\nof clusters in the ground state. In other words, inter-cluster interactions\nperturb the intra-cluster behaviour, such that each cluster may no longer be\nconsidered as an isolated system. Conversely, for dilute, weakly interacting\ncluster fluids little dependence on colloid concentration is observed, and we\nthus argue that it is reasonable to treat each cluster as an isolated system."
    },
    {
        "anchor": "Phase Separation of Polyelectrolytes: The Effect of Charge Regulation: Complex coacervation, known as the liquid-liquid phase separation of\nsolutions with oppositely charged polyelectrolytes, has attracted substantial\ninterest in recent years. We study the effect of the charge regulation (CR)\nmechanism on the complex coacervation by including short-range interactions\nbetween the charged sites on the polymer chains as well as an\nassociation-dissociation energy parameter in the CR mechanism. We investigate\nthe phase diagrams of two CR models: (i) the hopping CR model (HCR) and (ii)\nthe asymmetric CR model (ACR). It is shown that during the phase separation\nthat the polymers in the condensed phase are more charged than those in the\ndilute phase, in accordance with Le Chatelier's principle. In addition,\nsecondary CR effects also influence the change in the volume fraction of the\ntwo phases. The latter can cause the charge difference between the two phases\nto change nonmonotonically as a function of the CR parameters.",
        "positive": "Field-driven dynamics of nematic microcapillaries: Polymer-dispersed liquid crystal (PDLC) composites have long been a focus of\nstudy for their unique electro-optical properties which have resulted in\nvarious applications such as switchable (transparent/translucent) windows.\nThese composites are manufactured using desirable \"bottom-up\" techniques, such\nas phase separation of a liquid crystal/polymer mixture, which enable\nproduction of PDLC films at very large scales. LC domains within PDLCs are\ntypically spheroidal, as opposed to rectangular for an LCD panel, and thus\nexhibit substantially different behaviour in the presence of an external field.\nThe fundamental difference between spheroidal and rectangular nematic domains\nis that the former results in the presence of nanoscale orientational defects\nin LC order while the latter does not. Progress in the development and\noptimization of PDLC electro-optical properties has progressed at a relatively\nslow pace due to this increased complexity. In this work, continuum simulations\nare performed in order to capture the complex formation and electric\nfield-driven switching dynamics of approximations of PDLC domains. Using a\nsimplified elliptic cylinder (microcapillary) geometry as an approximation of\nspheroidal PDLC domains, the effects of geometry (aspect ratio), surface\nanchoring, and external field strength are studied through the use of the\nLandau--de Gennes model of the nematic LC phase."
    },
    {
        "anchor": "Universality of the melting curves for a wide range of interaction\n  potentials: We demonstrate that the melting curves of various model systems of\ninteracting particles collapse to (or are located very close to) a universal\nmaster curve on a plane of appropriately chosen scaled variables. The physics\nbehind this universality is discussed. An equation for the emerging \"universal\nmelting curve\" is proposed. The obtained results can be used to approximately\npredict melting of various substances in a wide range of conditions.",
        "positive": "Autophoretic motion in three dimensions: Janus particles with the ability to move phoretically in self-generated\nchemical concentration gradients are model systems for active matter. Their\nmotion typically consists of straight paths with rotational diffusion being the\ndominant reorientation mechanism. In this paper, we show theoretically that by\na suitable surface coverage of both activity and mobility, translational and\nrotational motion can be induced arbitrarily in three dimensions. The resulting\ntrajectories are in general helical, and their pitch and radius can be\ncontrolled by adjusting the angle between the translational and angular\nvelocity. Building on the classical mathematical framework for axisymmetric\nself-phoretic motion under fixed-flux chemical boundary condition, we first\nshow how to calculate the most general three-dimensional motion for an\narbitrary surface coverage of a spherical particle. After illustrating our\nresults on surface distributions, we next introduce a simple intuitive patch\nmodel to serve as a guide for designing arbitrary phoretic spheres."
    },
    {
        "anchor": "Cluster self-assembly condition for arbitrary interaction potentials: We present a sufficient criterion for the emergence of cluster phases in an\nensemble of interacting classical particles with repulsive two-body\ninteractions. Through a zero-temperature analysis in the low density region we\ndetermine the relevant characteristics of the interaction potential that make\nthe energy of a two-particle cluster-crystal become smaller than that of a\nsimple triangular lattice in two dimensions. The method leads to a mathematical\ncondition for the emergence of cluster crystals in terms of the sum of Fourier\ncomponents of a regularized interaction potential, which can be in principle\napplied to any arbitrary shape of interactions. We apply the formalism to\nseveral examples of bounded and unbounded potentials with and without\ncluster-forming ability. In all cases, the emergence of self-assembled cluster\ncrystals is well captured by the presented analytic criterion and verified with\nknown results from molecular dynamics simulations at vanishingly temperatures.\nOur work generalises known results for bounded potentials to repulsive\npotentials of arbitrary shape.",
        "positive": "Role of gravity or confining pressure and contact stiffness in granular\n  rheology: The steady shear rheology of granular materials is investigated in slow\nquasi-static states and inertial flows. The effect of the gravity field and\ncontact stiffness, which are conventionally trivialized is the focus of this\nstudy. Series of Discrete Element Method simulations are performed on a weakly\nfrictional granular assembly in a split-bottom geometry considering various\ngravity fields and contact stiffnesses. While traditionally the inertial\nnumber, i.e., the ratio of stress to strain-rate timescales describes the flow\nrheology, we find that a second dimensionless number, the ratio of softness and\nstress timescales, must also be included to characterize the bulk flow\nbehavior. For slow, quasi-static flows, the density increases while the\nmacroscopic friction decreases with respective increase in particle softness\nand gravity. This trend is added to the $\\mu(I)$ rheology and can be traced\nback to the anisotropy in the contact network, displaying a linear correlation\nbetween macroscopic friction and deviatoric fabric in the steady state.\nInterestingly, the linear relation holds when the external rotation rate is\nincreased for a given gravity field and contact stiffness."
    },
    {
        "anchor": "The shallow shell approach to Pogorelov's problem and the breakdown of\n  `mirror buckling': We present a detailed asymptotic analysis of the point indentation of an\nunpressurized, spherical elastic shell. Previous analyses of this classic\nproblem have assumed that for sufficiently large indentation depths, such a\nshell deforms by `mirror buckling' --- a portion of the shell inverts to become\na spherical cap with equal but opposite curvature to the undeformed shell. The\nenergy of deformation is then localized in a ridge in which the deformed and\nundeformed portions of the shell join together, commonly referred to as\nPogorelov's ridge. Rather than using an energy formulation, we revisit this\nproblem from the point of view of the shallow shell equations and perform an\nasymptotic analysis that exploits the largeness of the indentation depth. This\nreveals first that the stress profile associated with mirror buckling is\nsingular as the indenter is approached. This consequence of point indentation\nmeans that mirror buckling must be modified to incorporate the shell's bending\nstiffness close to the indenter and gives rise to an intricate asymptotic\nstructure with seven different spatial regions. This is in contrast with the\nthree regions (mirror-buckled, ridge and undeformed) that are usually assumed\nand yields new insight into the large compressive hoop stress that ultimately\ncauses the shell to buckle azimuthally.",
        "positive": "Graph topological transformations in space-filling cell aggregates: Cell rearrangements are fundamental mechanisms driving large-scale\ndeformations of living tissues. In three-dimensional (3D) space-filling cell\naggregates, cells rearrange through local topological transitions of the\nnetwork of cell-cell interfaces, which is most conveniently described by the\nvertex model. Since these transitions are not yet mathematically properly\nformulated, the 3D vertex model is generally difficult to implement. The few\nexisting implementations rely on highly customized and complex\nsoftware-engineering solutions, which cannot be transparently delineated and\nare thus mostly non-reproducible. To solve this outstanding problem, we propose\na reformulation of the vertex model. Our approach, called Graph Vertex Model\n(GVM), is based on storing the topology of the cell network into a knowledge\ngraph with a particular data structure that allows performing\ncell-rearrangement events by simple graph transformations. We find these\ntransformations consinsting of transformation patterns corresponding to T1\ntransitions, thereby unifying topological transitions in 2D and 3D\nspace-filling packings. This result suggests that the GVM's graph data\nstructure may be the most natural representation of cell aggregates and\ntissues. We use GVM to characterize solid-fluid transition in 3D cell\naggregates, driven by active noise and find aggregates undergoing efficient\nordering close to the transition point. In all, our work showcases knowledge\ngraphs as particularly suitable data models for structured storage, analysis,\nand manipulation of tissue data, which potentially has paradigm-shifting\nimplications for the fields of tissue biophysics and biology."
    },
    {
        "anchor": "Printing non-Euclidean solids: Geometrically frustrated solids with non-Euclidean reference metric are\nubiquitous in biology and are becoming increasingly relevant in technological\napplications. Often they acquire a targeted con- figuration of incompatibility\nthrough surface accretion of mass as in tree growth or dam construction. We use\nthe mechanics of incompatible surface growth to show that geometrical\nfrustration develop- ing during deposition can be fine-tuned to ensure a\nparticular behavior of the system in physiological (or working) conditions. As\nan illustration, we obtain an explicit 3D printing protocol for arteries, which\nguarantees stress uniformity under inhomogeneous loading, and for explosive\nplants, allowing a complete release of residual elastic energy with a single\ncut. Interestingly, in both cases reaching the physiological target requires\nthe incompatibility to have a topological (global) component.",
        "positive": "Meanfield treatment of Bragg scattering from a Bose-Einstein condensate: A unified semiclassical treatment of Bragg scattering from Bose-Einstein\ncondensates is presented. The formalism is based on the Gross-Pitaevskii\nequation driven by classical light fields far detuned from atomic resonance. An\napproximate analytic solution is obtained and provides quantitative\nunderstanding of the atomic momentum state oscillations, as well as a simple\nexpression for the momentum linewidth of the scattering process. The validity\nregime of the analytic solution is derived, and tested by three dimensional\ncylindrically symmetric numerical simulations."
    },
    {
        "anchor": "Effect of Poisson ratio on cellular structure formation: Mechanically active cells in soft media act as force dipoles. The resulting\nelastic interactions are long-ranged and favor the formation of strings. We\nshow analytically that due to screening, the effective interaction between\nstrings decays exponentially, with a decay length determined only by geometry.\nBoth for disordered and ordered arrangements of cells, we predict novel phase\ntransitions from paraelastic to ferroelastic and anti-ferroelastic phases as a\nfunction of Poisson ratio.",
        "positive": "Collisional Model of Energy Dissipation in 3D Granular Impact: We study the dynamic process occurring when a granular assembly is displaced\nby a solid impactor. The momentum transfer from the impactor to the target is\nshown to occur through sporadic, normal collisions of high force carrying\ngrains at the intruder surface. We therefore describe the stopping force of the\nimpact through a collisional based model. To verify the model in impact\nexperiments, we determine the forces acting on an intruder decelerating through\na dense granular medium using high-speed imaging of its trajectory. By varying\nthe intruder shape and granular target, intruder-grain interactions are\ninferred from the consequent path. As a result, we connect the drag to the\neffect of intruder shape and grain density based on a proposed collisional\nmodel."
    },
    {
        "anchor": "Nonmonotonic fracture behavior of polymer nanocomposites: Polymer composite materials are widely used for their exceptional mechanical\nproperties, notably their ability to resist large deformations. Here we examine\nthe failure stress and strain of rubbers reinforced by varying amounts of\nnano-sized silica particles. We find that small amounts of silica increase the\nfracture stress and strain, but too much filler makes the material become\nbrittle and consequently fracture happens at small deformations. We thus find\nthat as a function of the amount of filler there is an optimum in the breaking\nresistance at intermediate filler concentrations. We use a modified Griffith\ntheory to establish a direct relation between the material properties and the\nfracture behavior that agrees with the experiment.",
        "positive": "Exploring the effect of geometric coupling on friction and energy\n  dissipation in rough contacts of elastic and viscoelastic coatings: We study the frictional behavior of both elastic and viscoelastic thin\ncoatings bonded to a seemingly rigid substrate and sliding against a rough\nprofile in the presence of Coulomb friction at the interface. The aim is to\nexplore the effect of the coupling between the normal and tangential\ndisplacement fields arising from the finiteness of the material thickness and\nto quantify the contribution this can have on energy losses. We found that, due\nto normal-tangential coupling, asymmetric contacts and consequently additional\nfriction are observed even for purely elastic layers, indeed associated with\nzero bulk energy dissipation. Furthermore, enhanced viscoelastic friction is\nreported in the case of viscoelastic coatings due to coupling, this time also\nentailing larger bulk energy dissipation. Geometric coupling also introduces\nadditional interactions involving the larger scales normal displacements, which\nleads to a significant increase of the contact area, under given normal load,\ncompared to the uncoupled contacts. These results show that, in the case of\ncontact interfaces involving thin deformable coating bonded to significantly\nstiffer substrate, the effect of interfacial shear stresses on the frictional\nand contact behavior cannot be neglected."
    },
    {
        "anchor": "Patterns without patches: Hierarchical assembly of complex structures\n  from simple building blocks: Nanoparticles with \"sticky patches\" have long been proposed as building\nblocks for the self-assembly of complex structures. The synthetic realizability\nof such patchy particles, however, greatly lags behind predictions of patterns\nthey could form. Using computer simulations, we show that structures of the\nsame genre can be obtained from a solution of simple isotropic spheres,\nprovided control only over their sizes and a small number of binding\naffinities. In a first step, finite clusters of well-defined structure and\ncomposition emerge from natural dynamics with high yield. In effect a kind of\npatchy particle, these clusters can further assemble into a variety of complex\nsuperstructures, including filamentous networks, ordered sheets, and highly\nporous crystals.",
        "positive": "Stress anisotropy in confined populations of growing rods: Order and alignment are ubiquitous in growing colonies of rod-shaped bacteria\ndue to the nematic properties of the constituent particles. These effects are\nthe result of the active stresses generated by growth, passive mechanical\ninteractions between cells, and flow-induced effects due to the shape of the\nconfining container. However, how these contributing factors interact to give\nrise to the observed global alignment patterns remains elusive. Here, we study,\nin-silico, colonies of growing rod-shaped particles of different aspect ratios\nconfined in channel-like geometries. A spatially resolved analysis of the\nstress tensor reveals a strong relationship between near-perfect alignment and\nan inversion of stress anisotropy for particles with large length-to-width\nratios. We show that, in quantitative agreement with an asymptotic theory,\nstrong alignment can lead to a decoupling of active and passive stresses\nparallel and perpendicular to the direction of growth, respectively. We\ndemonstrate the robustness of these effects in a geometry that provides less\nrestrictive confinement and introduces natural perturbations in alignment. Our\nresults illustrate the complexity arising from the inherent coupling between\nnematic order and active stresses in growing active matter which is modulated\nby geometric and configurational constraints due to confinement."
    },
    {
        "anchor": "Collective behavior of quorum-sensing run-and-tumble particles in\n  confinement: We study a generic model for quorum-sensing bacteria in circular confinement.\nEvery bacterium produces signaling molecules, the local concentration of which\ntriggers a response when a certain threshold is reached. If this response\nlowers the motility then an aggregation of bacteria occurs, which differs\nfundamentally from standard motility-induced phase separation due to the\nlong-ranged nature of the concentration of signal molecules. We analyze this\nphenomenon analytically and by numerical simulations employing two different\nprotocols leading to stationary cluster and ring morphologies, respectively.",
        "positive": "Effect of the crystal size on the X-ray diffraction patterns of isolated\n  orthorhombic starches: A-type: The x-ray diffraction (XRD) patterns reported for starch in the literature\ndescribes it as a semicrystalline polymer that indicates that amorphous and\ncrystalline regions form it, and this is commonly accepted. However, these\npatterns have not been well interpreted according to the XRD theory, and the\ncrystal size effect has been neglected. A simulation of the effect of the\ncrystal size on the shape and width on XRD patterns for A-type (orthorhombic\nstructure, ICDD card No. 00-043-1858) using PDF-4 software shows that the\npatterns of starches are governed by the elastic and inelastic scattering\nproducing wide peaks. For isolated starches XRD patterns, the separation of\ninelastic and elastic scattering is not possible, then the calculation of the\ncrystalline percent or crystalline quality does not make any physics sense."
    },
    {
        "anchor": "Single-shot wideband active mircorheology using multiple-sinusoid\n  modulated Optical Tweezers: We employ multiple sinusoid modulated optical tweezers to measure the\nfrequency dependent rheological parameters of a linear viscoelastic fluid over\nfive decades of frequency in a single shot, hitherto not achieved using active\nmicrorheology alone. Thus, we spatially modulate a trapped probe particle\nembedded in a fluid medium with a combination of a square wave - which is by\ndefinition a superposition of odd sinusoidal harmonics - and a linear\nsuperposition of multiple sinusoids at a wideband frequency range, with\ncomplete control over the amplitude, frequency and relative phase of the\nmodulating signals. For the latter, we selectively excite the particle by\nlarger amplitudes at high frequencies where the particle response is low,\nthereby enabling wideband active microrheology with large signal-to-noise. This\nmitigates the principal issue associated with conventional active microrheology\n- which is low bandwidth - and also renders our method better in terms of\nsignal to noise, and faster compared to passive microrheology. We determine the\ncomplex viscoelastic parameters of the fluid by extracting the phase response\n(relative to input excitation) of the probe from the experimentally recorded\ntime series data of the probe displacement, and employing well-known\ntheoretical correlations thereafter. We test the efficacy of our method by\nstudying a linear viscoelastic media (polyacrylamide-water solution) at\ndifferent concentrations, and find good agreement of the measured fluid\nparameters with known literature values.",
        "positive": "On the effect of the thermostat in non-equilibrium molecular dynamics\n  simulations: The numerical investigation of the statics and dynamics of systems in\nnonequilibrium in general, and under shear flow in particular, has become more\nand more common. However, not all the numerical methods developed to simulate\nequilibrium systems can be successfully adapted to out-of-equilibrium cases.\nThis is especially true for thermostats. Indeed, even though thermostats\ndeveloped to work under equilibrium conditions sometimes display good agreement\nwith rheology experiments, their performance rapidly degrades beyond weak\ndissipation and small shear rates. Here we focus on gauging the relative\nperformances of three thermostats, Langevin, dissipative particle dynamics, and\nBussi-Donadio-Parrinello under varying parameters and external conditions. We\ncompare their effectiveness by looking at different observables and clearly\ndemonstrate that choosing the right thermostat (and its parameters) requires a\ncareful evaluation of, at least, temperature, density and velocity profiles. We\nalso show that small modifications of the Langevin and DPD thermostats greatly\nenhance their performance in a wide range of parameters."
    },
    {
        "anchor": "Long Distance Correlations in Molecular Orientations of Liquid Water and\n  Shape Dependant Hydrophobic Force: Liquid water, at ambient conditions, has short-range density correlations\nwhich are well known in literature. Surprisingly, large scale molecular\ndynamics simulations reveal an unusually long-distance correlation in\n`longitudinal' part of dipole-dipole orientational correlations. It is\nnon-vanishing even at 75 \\AA{} and falls-off exponentially with a correlation\nlength of about 24 \\AA{} beyond solvation region. Numerical evidence suggests\nthat the long range nature of dipole-dipole correlation is due to underlying\nfluctuating network of hydrogen-bonds in the liquid phase. This correlation is\nshown to give a shape dependant attraction between two hydrophobic surfaces at\nlarge distances of separation and the range of this attractive force is in\nagreement with experiments. In addition it is seen that quadrupolar\nfluctuations vanish within the first solvation peak (3 \\AA{})",
        "positive": "Morphology Scaling of Drop Impact onto a Granular Layer: We investigate the impact of a free-falling water drop onto a granular layer.\nFirst, we constructed a phase diagram of crater shapes with two control\nparameters, impact speed and grain size. A low-speed impact makes a deeper\ncylindrical crater in a fluffy granular target. After high-speed impacts, we\nobserved a convex bump higher than the initial surface level instead of a\ncrater. The inner ring can be also observed in medium impact speed regime.\nQuantitatively, we found a scaling law for crater radius with a dimensionless\nnumber consisting of impact speed and density ratio between the bulk granular\nlayer and water drop. This scaling demonstrates that the water drop deformation\nis crucial to understand the crater morphology."
    },
    {
        "anchor": "Mechanical Failure of a Small and Confined Solid: Starting from a commensurate triangular thin solid strip, confined within two\nhard structureless walls, a stretch along its length introduces a rectangular\ndistortion. Beyond a critical strain the solid fails through nucleation of\n\"smectic\"-like bands. We show using computer simulations and simple density\nfunctional based arguments, how a solid-smectic transition mediates the\nfailure. Further, we show that the critical strain introducing failure is {\\em\ninversely} proportional to the channel width i.e. thinner strips are stronger!",
        "positive": "Nematic director slippage: Role of the angular momentum of light: We propose a theoretical model of the light-induced director slippage effect.\nIn this effect the bulk director reorientation contributes to the surface\ndirector reorientation It is found that the director and ellipticity profiles,\nobtained in the geometric optics approximation, are dependent on the\nellipticity of the incident light wave. The director distribution is spatially\nmodulated in linearly polarized light but grows monotonically in circularly\npolarized light. The surface director deviation has been examined, and\ncomparison made with existing experimental data, which then permits the\nmagnitude of the orientational nonlinearity coefficient to be calculated."
    },
    {
        "anchor": "Diffusional Anomaly and network dynamics in liquid silica: The present study applies the power spectral analysis technique to understand\nthe diffusional anomaly in liquid silica, modeled using the BKS potential.\nMolecular dynamics simulations have been carried out to show that power\nspectrum of tagged particle potential energy of silica shows a regime with 1/f\ndependence on frequency f which is the characteristic signature of multiple\ntime-scale behaviour in networks. As demonstrated earlier in the case of water\n(J. Chem. Phys., 122, 104507 (2005)), the variations in the mobility associated\nwith the diffusional anomaly are mirrored in the scaling exponent alpha\nassociated with this multiple time-scale behaviour. Our results indicate that\nin the anomalous regime, as the local tetrahedral order decreases with\ntemperature or pressure, the coupling of local modes to network reorganisations\nincreases and so does the diffusivity. This symmetry-dependence of the\nvibrational couplings is responsible for the connection between the structural\nand diffusional anomalies.",
        "positive": "Multiscale entanglement in ring polymers under spherical confinement: The interplay of geometrical and topological entanglement in semiflexible\nknotted polymer rings confined inside a spherical cavity is investigated using\nadvanced numerical methods. By using stringent and robust algorithms for\nlocating knots, we characterize how the knot length lk depends on the ring\ncontour length, Lc and the radius of the confining sphere, Rc . In the no- and\nstrong- confinement cases we observe weak knot localization and complete knot\ndelocalization, respectively. We show that the complex interplay of lk, Lc and\nRc that seamlessly bridges these two limits can be encompassed by a simple\nscaling argument based on deflection theory. The same argument is used to\nrationalize the multiscale character of the entanglement that emerges with\nincreasing confinement."
    },
    {
        "anchor": "Integration Schemes for Dissipative Particle Dynamics Simulations: From\n  Softly Interacting Systems Towards Hybrid Models: We examine the performance of various commonly used integration schemes in\ndissipative particle dynamics simulations. We consider this issue using three\ndifferent model systems, which characterize a variety of different conditions\noften studied in simulations. Specifically we clarify the performance of\nintegration schemes in hybrid models, which combine microscopic and meso-scale\ndescriptions of different particles using both soft and hard interactions. We\nfind that in all three model systems many commonly used integrators may give\nrise to surprisingly pronounced artifacts in physical observables such as the\nradial distribution function, the compressibility, and the tracer diffusion\ncoefficient. The artifacts are found to be strongest in systems, where\ninterparticle interactions are soft and predominated by random and dissipative\nforces, while in systems governed by conservative interactions the artifacts\nare weaker. Our results suggest that the quality of any integration scheme\nemployed is crucial in all cases where the role of random and dissipative\nforces is important, including hybrid models where the solvent is described in\nterms of soft potentials.",
        "positive": "Metamaterials for Active Colloid Transport: Transport phenomena in out-of-equilibrium systems is immensely important in a\nmyriad of applications in biology, engineering and physics. Complex\nenvironments, such as the cytoplasm or porous media, can substantially affect\nthe transport properties of such systems. In particular, recent interest has\nfocused on how such environments affect the motion of active systems, such as\ncolloids and organisms propelled by directional driving forces. Nevertheless,\nthe transport of active matter with non-directional (rotational) activity is\nyet to be understood, despite the ubiquity of rotating modes of motion in\nsynthetic and natural systems. Here, we report on the discovery of\nspatiotemporal metamaterial systems that are able to dictate the transport of\nspinning colloids in exquisite ways based on solely two parameters: frequency\nof spin modulation in time and the symmetry of the metamaterial. We demonstrate\nthat dynamic modulations of the amplitude of spin on a colloid in lattices with\nrotational symmetry give rise to non-equilibrium ballistic transport bands,\nreminiscent of those in Floquet-Bloch systems. By coupling these temporal\nmodulations with additional symmetry breaking in the lattice, we show selective\ncontrol from 4-way to 2-way to unidirectional motion. Our results provide\ncritical new insights into the motion of spinning matter in complex\n(biological) systems. Furthermore, our work can also be used for designing\nsystems with novel and unique transport properties for application in, for\nexample, smart channel-less microfluidics, micro-robotics, or colloidal\nseparations."
    },
    {
        "anchor": "Splitting instability of cellular structures in the Ginzburg-Landau\n  model under the feedback control: We study numerically a Ginzburg-Landau type equation for micelles in two\ndimensions. The domain size and the interface length of a cellular structure\nare controlled by two feedback terms. The deformation and the successive\nsplitting of the cellular structure are observed when the controlled interface\nlength is increased. The splitting instability is further investigated using\ncoupled mode equations to understand the bifurcation structure.",
        "positive": "Larmor Frequency in Heterogeneous Media: The Larmor frequency shift is found in porous media consisting of\nNMR-reporting fluid filling a connected pore within an NMR-invisible matrix for\nthe case of fast diffusion in the fluid. The matrix material has a distinct\nlocation-independent anisotropic magnetic susceptibility tensor that induces a\nheterogeneous microscopic magnetic field when exposed to the strong main field\nof an NMR device. Aside from the connectivity of the pore, the matrix geometry\nis arbitrary."
    },
    {
        "anchor": "Systematic Modification of Functionality in Disordered Elastic Networks\n  Through Free Energy Surface Tailoring: Advances in manufacturing and characterization of complex molecular systems\nhave created a need for new methods for design at molecular length scales.\nEmerging approaches are increasingly relying on the use of Artificial\nIntelligence (AI), and the training of AI models on large data libraries. This\nparadigm shift has led to successful applications, but shortcomings related to\ninterpretability and generalizability continue to pose challenges. Here, we\nexplore an alternative paradigm in which AI is combined with physics-based\nconsiderations for molecular and materials engineering. Specifically,\ncollective variables, akin to those used in enhanced sampled simulations, are\nconstructed using a machine learning (ML) model trained on data gathered from a\nsingle system. Through the ML-constructed collective variables, it becomes\npossible to identify critical molecular interactions in the system of interest,\nthe modulation of which enables a systematic tailoring of the system's free\nenergy landscape. To explore the efficacy of the proposed approach, we use it\nto engineer allosteric regulation, and uniaxial strain fluctuations in a\ncomplex disordered elastic network. Its successful application in these two\ncases provides insights regarding how functionality is governed in systems\ncharacterized by extensive connectivity, and points to its potential for design\nof complex molecular systems.",
        "positive": "Elastic Cherenkov effects in transversely isotropic soft materials-I:\n  Theoretical analysis, simulations and inverse method: A body force concentrated at a point and moving at a high speed can induce\nshear-wave Mach cones in dusty-plasma crystals or soft materials, as observed\nexperimentally and named the elastic Cherenkov effect (ECE). The ECE in soft\nmaterials forms the basis of the supersonic shear imaging (SSI) technique, an\nultrasound-based dynamic elastography method applied in clinics in recent\nyears. Previous studies on the ECE in soft materials have focused on isotropic\nmaterial models. In this paper, we investigate the existence and key features\nof the ECE in anisotropic soft media, by using both theoretical analysis and\nfinite element (FE) simulations, and we apply the results to the non=invasive\nand non-destructive characterization of biological soft tissues. We also\ntheoretically study the characteristics of the shear waves induced in a\ndeformed hyperelastic anisotropic soft material by a source moving with high\nspeed, considering that contact between the ultrasound probe and the soft\ntissue may lead to finite deformation. On the basis of our theoretical analysis\nand numerical simulations, we propose an inverse approach to infer both the\nanisotropic and hyperelastic parameters of incompressible transversely\nisotropic (TI) soft materials. Finally, we investigate the properties of the\nsolutions to the inverse problem by deriving the condition numbers in\nanalytical form and performing numerical experiments. In Part II of the paper,\nboth ex vivo and in vivo experiments are conducted to demonstrate the\napplicability of the inverse method in practical use."
    },
    {
        "anchor": "Entropic lattice Boltzmann methods: We present a general methodology for constructing lattice Boltzmann models of\nhydrodynamics with certain desired features of statistical physics and kinetic\ntheory. We show how a methodology of linear programming theory, known as\nFourier-Motzkin elimination, provides an important tool for visualizing the\nstate space of lattice Boltzmann algorithms that conserve a given set of\nmoments of the distribution function. We show how such models can be endowed\nwith a Lyapunov functional, analogous to Boltzmann's H, resulting in\nunconditional numerical stability. Using the Chapman-Enskog analysis and\nnumerical simulation, we demonstrate that such entropically stabilized lattice\nBoltzmann algorithms, while fully explicit and perfectly conservative, may\nachieve remarkably low values for transport coefficients, such as viscosity.\nIndeed, the lowest such attainable values are limited only by considerations of\naccuracy, rather than stability. The method thus holds promise for\nhigh-Reynolds number simulations of the Navier-Stokes equations.",
        "positive": "Rheology in dense assemblies of spherocylinders: frictional vs.\n  frictionless: Using molecular dynamics simulations, we study the steady shear flow of dense\nassemblies of anisotropic spherocylindrical particles of varying aspect ratios.\nComparing frictionless and frictional particles we discuss the specific role of\nfrictional inter-particle forces for the rheological properties of the system.\nIn the frictional system we evidence a shear-thickening regime, similar to that\nfor spherical particles. Furthermore, friction suppresses alignment of the\nspherocylinders along the flow direction. Finally, the jamming density in\nfrictional systems is rather insensitive to variations in aspect-ratio, quite\ncontrary to what is known from frictionless systems."
    },
    {
        "anchor": "Percolation transition in phase separating active fluid: The motility-induced phase separation exhibited by active particles with\nrepulsive interactions is well known. We show that the interaction softness of\nactive particles destabilizes the highly ordered dense phase, leading to the\nformation of a porous cluster which spans the system. This \\emph{soft limit}\ncan also be achieved if the particle motility is increased beyond a critical\nvalue, at which the system clearly exhibits all the characteristics of a\nstandard percolation transition. We also show that in the athermal limit,\nactive particles exhibit similar transitions even at low motility. With these\nadditional new phases, the phase diagram of repulsive active particles is\nrevealed to be richer than what was previously conceived.",
        "positive": "Fluctuation-induced forces between inclusions in a fluid membrane under\n  tension: We discuss the fluctuation-induced force, a finite-temperature analog of the\nCasimir force, between two inclusions embedded in a fluid membrane under\ntension. We suggest a method to calculate this Casimir interaction in the most\ngeneral case, where membrane fluctuations are governed by the combined action\nof surface tension, bending modulus, and the Gaussian rigidity. We find that\nthe surface tension strongly modifies the power law in the separation\ndependence of the Casimir interaction. This results in a strong suppression of\nthe Casimir force at separations beyond a characteristic length, which could\naffect protein aggregation dynamics in cell membranes."
    },
    {
        "anchor": "An exact reformulation of the Bose-Hubbard model in terms of a\n  stochastic Gutzwiller ansatz: We extend our exact reformulation of the bosonic many-body problem in terms\nof a stochastic Hartree ansatz to a stochastic Gutzwiller ansatz for the Bose\nHubbard model. This makes the corresponding Monte Carlo method more efficient\nfor strongly correlated bosonic phases like the Mott insulator phase or the\nTonks phase. We present a first numerical application of this stochastic method\nto a system of impenetrable bosons on a 1D lattice showing the transition from\nthe discrete Tonks gas to the Mott phase as the chemical potential is\nincreased.",
        "positive": "Nucleation of stable cylinders from a metastable lamellar phase in a\n  diblock copolymer melt: The nucleation of a droplet of stable cylinder phase from a metastable\nlamellar phase is examined within the single-mode approximation to the\nBrazovskii model for diblock copolymer melts. By employing a variational ansatz\nfor the droplet interfacial profile, an analytic expression for the interfacial\nfree-energy of an interface of arbitrary orientation between cylinders and\nlamellae is found. The interfacial free-energy is anisotropic, and is lower\nwhen the cylinder axis is perpendicular to the interface than when the\ncylinders lie along the interface. Consequently, the droplet shape computed via\nthe Wulff construction is lens-like, being flattened along the axis of the\ncylinders. The size of the critical droplet and the nucleation barrier are\ndetermined within classical nucleation theory. Near the lamellar/cylinder phase\nboundary, where classical nucleation theory is applicable, critical droplets of\nsize 30--400 cylinders across with aspect ratios of 4--10 and nucleation\nbarriers of 30--40 k_B T are typically found. The general trend is to larger\ncritical droplets, higher aspect ratios and smaller nucleation barriers as the\nmean-field critical point is approached."
    },
    {
        "anchor": "Thermodynamics, Structure, and Dynamics of Water Confined between\n  Hydrophobic Plates: We perform molecular dynamics simulations of 512 water-like molecules that\ninteract via the TIP5P potential and are confined between two smooth\nhydrophobic plates that are separated by 1.10 nm. We find that the anomalous\nthermodynamic properties of water are shifted to lower temperatures relative to\nthe bulk by $\\approx 40$ K. The dynamics and structure of the confined water\nresemble bulk water at higher temperatures, consistent with the shift of\nthermodynamic anomalies to lower temperature. Due to this $T$ shift, our\nconfined water simulations (down to $T = 220$ K) do not reach sufficiently low\ntemperature to observe a liquid-liquid phase transition found for bulk water at\n$T\\approx 215$ K using the TIP5P potential. We find that the different\ncrystalline structures that can form for two different separations of the\nplates, 0.7 nm and 1.10 nm, have no counterparts in the bulk system, and\ndiscuss the relevance to experiments on confined water.",
        "positive": "Dynamics of filaments and membranes in a viscous fluid: Motivated by the motion of biopolymers and membranes in solution, this\narticle presents a formulation of the equations of motion for curves and\nsurfaces in a viscous fluid. We focus on geometrical aspects and simple\nvariational methods for calculating internal stresses and forces, and we derive\nthe full nonlinear equations of motion. In the case of membranes, we pay\nparticular attention to the formulation of the equations of hydrodynamics on a\ncurved, deforming surface. The formalism is illustrated by two simple case\nstudies: (1) the twirling instability of straight elastic rod rotating in a\nviscous fluid, and (2) the pearling and buckling instabilities of a tubular\nliposome or polymersome."
    },
    {
        "anchor": "Non-trivial activity dependence of static length scale and critical\n  tests of active random first-order transition theory: Effects of activity on glassy dynamics are fundamental in several biological\nprocesses. Active glasses extend the scope of the equilibrium problem and\nprovide new control parameters to probe different theoretical aspects. In the\ntheory of glassy dynamics, different length scales play pivotal roles. Here,\nfor the first time, we present results for the static length scale, $\\xi_S$, in\nan active glass via large-scale molecular dynamics simulations for model active\nglasses in three spatial dimensions. We show that although the relaxation\ndynamics are equilibrium-like, activity has non-trivial effects on $\\xi_S$.\n$\\xi_S$ plays the central role in the random first-order transition (RFOT)\ntheory. Thus, our work provides critical tests for the active RFOT theory, a\nphenomenological extension of its equilibrium counterpart. We find that the two\nexponents, $\\theta$ and $\\psi$, within the theory, become activity-dependent,\nexposing the non-trivial effects of activity on $\\xi_S$. However, the\ncombination of $\\theta$ and $\\psi$, which controls the relaxation dynamics,\nremains nearly independent of activity leading to the effectively\nequilibrium-like behavior. Interestingly, $\\xi_S$ shows higher growth in an\nactive glass; this should help better comparison of theories with simulations\nand experiments.",
        "positive": "Renormalized Surface Charge Density for a Strongly Charged Plate in\n  Asymmetric Electrolytes: Asymptotic Exact Results in Poisson Boltzmann Theory: The Poisson-Boltzmann equation for a strongly charged plate inside a generic\ncharge-asymmetric electrolyte is solved using the method of asymptotic\nmatching. Both near field and far field asymptotic behaviors of the potential\nare systematically analyzed. Using these expansions, the renormalized surface\ncharge density is obtained as an asymptotic series in terms of the bare surface\ncharge density."
    },
    {
        "anchor": "Micromechanical measurements of local plastic events in granular\n  materials: Understanding the relationship between micromechanics and macroscopic plastic\ndeformation is vital for elucidating the deformation mechanism of amorphous\nsolids, such as granular materials. In this study, we directly measure T1\nevents, which are topological rearrangements of particles, and the associated\nmicroscopic stresses in dense packings of photoelastic disks under pure shear.\nWe observe a remarkable similarity between the evolution of the total number of\nT1 events and the global stress-strain curve. The competition between the birth\nand death of T1 events establishes a dynamic equilibrium after the yield\nstrain, contributing to the overall plastic behavior. Despite the erratic\nstress fluctuations of individual T1 events, the local stresses decrease on\naverage once T1 events occur, indicating their soft characteristics.\nFurthermore, we demonstrate that the microscopic stress fluctuations exhibit a\nlong-range anisotropic spatial correlation similar to the Eschelby character,\nbut with a distinct scaling of $r^{-1.5}$. Interestingly, we also find a\nstriking similarity in the correlation functions of T1 and non-T1 regions.\nThese findings establish a significant connection between macroscopic\nmechanical behavior and the elementary deformation of T1 events, shedding light\non the fundamental understanding of granular materials as amorphous solids with\ncontact-scale plastic deformation.",
        "positive": "Charge-, salt- and flexoelectricity-driven anchoring effects in nematics: We investigate the effects of electric double layers and flexoelectricity on\nthe surface anchoring in general nematic fluids. Within a simplified model, we\ndemonstrate for a nematic electrolyte how the surface anchoring strength can be\naffected by the surface charge, bulk ion concentration and/or flexoelectricity,\neffectively changing not only the magnitude of the anchoring but also the\nanchoring type, such as from planar to tilted. In particular, we envisage\npossible tuning of the anchoring strength by the salt concentration in the\nregime where sufficiently strong electrostatic anchoring, as controlled by the\n(screened) surface charge, can compete with the non-electrostatic anchoring.\nThis effect is driven by the competing energetic-torque couplings between\nnematic director and the emergent electrostatic potential, due to surface\ncharge, ions and flexoelectricity. Our findings propose a way of influencing\nsurface anchoring by using electrostatic effects, which could be used in\nvarious aspects, including in the self-assembly of colloidal particles in\nnematic fluids, optical and display patterns, and sensing."
    },
    {
        "anchor": "Evanescent Wave Dynamic Light Scattering of Turbid Media: Dynamics light scattering (DLS) is a widely used techniques to characterize\ndynamics in soft phases. Evanescent Wave DLS refers to the case of total\ninternal reflection DLS that probes near interface dynamics. We here\ninvestigate the use of EWDLS for turbid sample. Using combination of\nray-tracing simulation and experiments, we show that a significant fraction of\nthe detected photons are scattered once and has phase shifts distinct from the\nmultiple scattering fraction. It follows that the measured correlation can be\nseparated into two contributions: a single scattering one arising from the\nevanescent wave scattering, providing information on motion of the \"scatterers\"\nand the associated near wall dynamics and a multiple scattering contribution\noriginating from scattering within the bulk of the sample. In case of turbid\nenough samples, the latter provides diffusive wave spectroscopy (DWS) -like\ncorrelation contribution. The validity of the approach is validated using\nturbid colloidal dispersion at rest and under shear. At rest we used\ndepolarized scattering to distinguish both contributions. Under shear, the two\ncontributions can easily be distinguished as the near wall dynamics and the\nbulk one are well separated. Information of both the near wall flow and the\nbulk flow can be retrieved from a single experiment. The simple structure of\nthe measured correlation is opening the use of EWDLS for a large range of\nsamples.",
        "positive": "Disarrangements and instabilities in 1D hyperelasticity: In the present work, the overall nonlinear elastic behavior of a 1D\nmulti-modular structure incorporating possible imperfections at the discrete\n(micro-scale) level, is derived with respect to both tensile and compressive\napplied loads. The model is built up through the repetition of n units, each\none comprising two rigid rods having equal lengths, linked by means of\npointwise constraints capable to elastically limit motions in terms of relative\ntranslations (sliders) and rotations (hinges). The mechanical response of the\nstructure is analyzed by varying the number n of the elemental moduli, as well\nas in the limit case of infinite number of infinitesimal constituents, in light\nof the theory of (first order) Structured Deformations (SDs), that interprets\nthe deformation of any continuum body as the projection, at the macroscopic\nscale, of geometrical changes occurring at the level of its sub-macroscopic\nelements. In this way, a wide family of nonlinear elastic behaviors is\ngenerated by tuning internal microstructural parameters, the tensile buckling\nand the classical Euler Elastica under compressive loads resulting as special\ncases in the so-called continuum limit, say when n tends to 1. Finally, by\nplotting the results in terms of first Piola-Kirchhoff stress versus\nmacroscopic stretch, it is for the first time demonstrated that such SDs-based\n1D models can be helpfully used to generalize some standard hyperelastic\nbehaviors by additionally taking into account instability phenomena and\nconcealed defects."
    },
    {
        "anchor": "Non-linear effects in electrolytes at large applied voltage: The steady state of ions diffusion in polymer electrolytes at arbitrary\napplied voltage is analyzed in the framework of the Nernst-Planck-Poisson\nequation (NPP). The exact solution of the set of equations is found without the\nassumption of low ions concentration. The solution is independent of the\nkinetic properties of the system. At constant voltage there is a master curve\nfor concentration in terms of the initial concentration. Enhancing the voltage\ncauses an increase of the ion concentration gradient and consequently the\napplicability of the NPP is violated for high voltages. The analytical finding\nis estimated by using experimental data from recent measurements (P. Kohn et al\nPhys. Rev. Left. 99, 086104 (2007)). As the result we find an upper bound for\nthe validity of the NPP. Above this voltage higher order gradient terms become\nrelevant.",
        "positive": "Brownian particles on rough substrates: Relation between the\n  intermediate subdiffusion and the asymptotic long-time diffusion: Brownian particles in random potentials show an extended regime of\nsubdiffusive dynamics at intermediate times. The asymptotic diffusive behavior\nis often established at very long times and thus cannot be accessed in\nexperiments or simulations. For the case of one-dimensional random potentials\nwith Gaussian distributed energies, we present a detailed analysis of\nexperimental and simulation data. It is shown that the asymptotic long-time\ndiffusion coefficient can be related to the behavior at intermediate times,\nnamely the minimum of the exponent that characterizes subdiffusion and hence\ncorresponds to the maximum degree of subdiffusion. As a consequence,\ninvestigating only the dynamics at intermediate times is sufficient to predict\nthe order of magnitude of the long-time diffusion coefficient and the timescale\nat which the crossover from subdiffusion to diffusion occurs, i.e. when the\nlong-time diffusive regime and hence thermal equilibrium is established."
    },
    {
        "anchor": "Granular mixtures discharging through a silo with eccentric orifice\n  location: We used the discrete element method (DEM) to study the flow dynamics of a\nmixture of dumbbells and discs for two silo cases: 1. orifice situated on the\nlateral wall and 2. multiple orifices placed on the base of a two-dimensional\nsilo. The time-averaged flow fields of various parameters like velocity, area\nfraction, pressure, shear stress etc, obtained from coarse-graining technique\nare presented for both the above-mentioned cases. A modified Beverloo scaling\nis reported for the flow discharging through the lateral orifice. The dynamic\nfriction is found to increase with an increase in the addition of dumbbells.\nThis resulted in a decrease in the flow rate through a lateral orifice with the\naddition of dumbbells. Self-similar velocity profiles are observed for mixtures\nfor the whole range of lateral orifice widths studied. The flow rate decreases\nwith an increase in the inter-orifice distance L/d for the multiple orifice\ncase. The velocity profile and flow fields revealed an interaction zone between\nthe two orifices at small L/d which is almost absent when the orifices are wide\napart. This interaction zone or flow through an orifice influenced by the\npresence of an adjacent orifice is the reason for a higher velocity above each\nof the orifices thus resulting in a higher flow rate at small L/d. The stagnant\nzone between the orifices is found to expand with an increase in the\ninter-orifice distance which yields in an increase in the shear stress between\neach of the orifices and the stagnant zone.",
        "positive": "Two-component self-contracted droplets: long-range attraction and\n  confinement effects: Marangoni self-contracted droplets are formed by a mixture of two liquids,\none of larger surface tension and larger evaporation rate than the other. Due\nto evaporation, the droplets contract to a stable contact angle instead of\nspreading on a wetting substrate. This gives them unique properties, including\nabsence of pinning force and ability to move under vapor gradients, self- and\nexternally imposed. We first model the dynamics of attraction in an unconfined\ngeometry and then study the effects of confinement on the attraction range and\ndynamics, going from minimal confinement (vertical boundary), to medium\nconfinement (2-D vapor diffusion) and eventually strong confinement (1-D).\n\"Self-induced\" motion is observed when single droplets are placed close to a\nvapor boundary toward which they are attracted, the boundary acting as an image\ndroplet with respect to itself. When two droplets are confined between two\nhorizontal plates, they interact at a longer distance with modified dynamics.\nFinally, confining the droplet in a tunnel, the range of attraction is greatly\nenhanced, as the droplet moves all the way up the tunnel when an external\nhumidity gradient is imposed. \"Self-induced\" motion is also observed, as the\ndroplet can move by itself towards the center of the tunnel. Confinement\ngreatly increase the range at which droplets interact as well as their lifetime\nand thus greatly expands the control and design possibilities for applications\noffered by self-contracted droplets."
    },
    {
        "anchor": "Phase Separation in Charge-Stabilized Colloidal Suspensions: Influence\n  of Nonlinear Screening: The phase behavior of charge-stabilized colloidal suspensions is modeled by a\ncombination of response theory for electrostatic interparticle interactions and\nvariational theory for free energies. Integrating out degrees of freedom of the\nmicroions (counterions, salt ions), the macroion-microion mixture is mapped\nonto a one-component system governed by effective macroion interactions. Linear\nresponse of microions to the electrostatic potential of the macroions results\nin a screened-Coulomb (Yukawa) effective pair potential and a one-body volume\nenergy, while nonlinear response modifies the effective interactions [A. R.\nDenton, \\PR E {\\bf 70}, 031404 (2004)]. The volume energy and effective pair\npotential are taken as input to a variational free energy, based on\nthermodynamic perturbation theory. For both linear and first-order nonlinear\neffective interactions, a coexistence analysis applied to aqueous suspensions\nof highly charged macroions and monovalent microions yields bulk separation of\nmacroion-rich and macroion-poor phases below a critical salt concentration, in\nqualitative agreement with predictions of related linearized theories [R. van\nRoij, M. Dijkstra, and J.-P. Hansen, \\PR E {\\bf 59}, 2010 (1999); P. B. Warren,\n\\JCP {\\bf 112}, 4683 (2000)]. It is concluded that nonlinear screening can\nmodify phase behavior but does not necessarily suppress bulk phase separation\nof deionized suspensions.",
        "positive": "Pair interaction ordering in fluids with random interactions: We use molecular dynamics simulations in 2d to study multi-component fluid in\nthe limiting case where {\\it all the particles are different} (APD). The\nparticles are assumed to interact via Lennard-Jones (LJ) potentials, with\nidentical size parameters but their pair interaction parameters are generated\nat random from a uniform or from a peaked distribution. We analyze both the\nglobal and the local properties of these systems at temperatures above the\nfreezing transition and find that APD fluids relax into a non-random state\ncharacterized by clustering of particles according to the values of their pair\ninteraction parameters (particle-identity ordering)."
    },
    {
        "anchor": "The Dielectric Breakdown Model at Small $\u03b7$: Pole Dynamics: We consider the dielectric breakdown model in the limit $\\eta\\to 0^+$. A\ndifferential equation describing the surface growth is derived; this equation\nis KPZ plus a term causing linear instability, and includes a short-distance\nregularization similar to a viscosity. The equation exhibits an interesting\ndynamics in terms of poles, permitting us to derive a large family of solutions\nto the equation of motion. In terms of poles, we find all stationary\nconfigurations of the surface, and analytically calculate their stability. For\neach value of the viscosity, only one stable configuration is found, but this\nconfiguration is nonlinearly unstable in the presence of an exponentially small\namount of noise. The present approach may be useful in understanding the\ndynamics for finite $\\eta$, in particular the DLA model, in terms of\nperturbations to the infinitesimal $\\eta$ problem.",
        "positive": "Lattice model for self-folding at the microscale: Three-dimensional shell-like structures can be obtained spontaneously at the\nmicroscale from the self-folding of 2D templates of rigid panels. At least for\nsimple structures, the motion of each panel is consistent with a Brownian\nprocess and folding occurs through a sequence of binding events, where pairs of\npanels meet at a specific closing angle. Here, we propose a lattice model to\ndescribe the dynamics of self-folding. As an example, we study the folding of a\npyramid of N lateral faces. We combine analytical and numerical Monte Carlo\nsimulations to find how the folding time depends on the number of faces,\nclosing angle, and initial configuration. Implications for the study of more\ncomplex structures are discussed."
    },
    {
        "anchor": "The Newtonian mechanics of a Vibrot: A mechanical model was developed to describe the behaviour of a device able\nto transform vibrations into rotations, named Vibrot. The theoretical model,\ndeveloped in the newtonian formulation of mechanics, was able to reproduce\nqualitatively all the experimental results existing in the literature, and\nquantitatively some of them.",
        "positive": "Experimental observation of the intricate free-energy landscape for a\n  soft glassy system: In the free energy landscape picture of glassy systems, the slow dynamics\ncharacteristic of these systems is believed to be due to the existence of a\ncomplicated free-energy landscape with many local minima. We show here that for\na colloidal glassy material multiple paths can be taken through the free energy\nlandscape, that can even lead to different 'final' non-ergodic states at the\nlate stages of aging. We provide clear experimental evidence for the\ndistinction of gel and glassy states in the system and show that for a range of\ncolloid concentrations, the transition to non-ergodicity can occur in either\ndirection (gel or glass), and may be accompanied by 'hesitations' between the\ntwo directions. This shows that colloidal gels and glasses are merely global\nfree-energy minima in the same free energy landscape, and that the paths\nleading to these minima can indeed be complicated."
    },
    {
        "anchor": "Antiferroelectric Smectic Ordering as a Prelude to the Ferroelectric\n  Nematic:Introducing the Smectic $Z_A$ Phase: We have structurally characterized the liquid crystal phase that appears as\nan intermediate state when a dielectric nematic, having polar disorder of its\nmolecular dipoles, transitions to the almost perfectly polar-ordered\nferroelectric nematic. This intermediate phase, which fills a 100-year-old void\nin the taxonomy of smectics and which we term the \"smectic $Z_A$\", is\nantiferroelectric, with the nematic director and polarization oriented parallel\nto smectic layer planes, and the polarization alternating in sign from layer to\nlayer. The period of this polarization wave ($\\sim$180 A) is mesoscopic,\ncorresponding to $\\sim$40 molecules side-by-side, indicating that this lamellar\nstructure is collectively stabilized. A Landau free energy, originally\nformulated to model incommensurate antiferroelectricity in crystals, describes\nthe key features of the nematic-Sm$Z_A$-ferroelectric nematic phase sequence.",
        "positive": "Excluded Volume in Protein Sidechain Packing: To examine the relationship between sidechain geometry and sidechain packing,\nwe use an all-atom Monte Carlo simulation to sample the large space of\nsidechain conformations. We study three models of excluded volume and use\numbrella sampling to effectively explore the entire space. We find that while\nexcluded volume constraints reduce the size of conformational space by many\norders of magnitude, the number of allowed conformations is still large. An\naverage repacked conformation has 20% of its chi angles in a non-native state.\nInterestingly, well-packed conformations, with up to 50% non-native chi's\nexist. Entropy is distributed non-uniformly over positions, and we partially\nexplain the observed distribution using rotamer probabilities derived from the\npdb database. In spite of our finding that 65% of the native rotamers and 85%\nof chi 1 angles can be correctly predicted on the basis of excluded volume\nonly, 95% of positions can accomodate more than 1 rotamer in simulation. We\nestimate that in order to quench the sidechain entropy observed in the presence\nof excluded volume interactions, other interactions (hydrophobic, polar,\nelectrostatic) must provide an additional stabilization of at least 0.6 kT per\nresidue in order to single out the native state."
    },
    {
        "anchor": "Evaporative Deposition in Receding Drops: We present a framework for calculating the surface density profile of a stain\ndeposited by a drop with a receding contact line. Unlike a pinned drop, a\nreceding drop pushes fluid towards its interior, continuously deposits mass\nacross its substrate as it evaporates, and does not produce the usual \"coffee\nring.\" For a thin, circular drop with a constant evaporation rate, we find the\nsurface density of the stain goes as $\\eta(r) \\propto\n\\left(\\left(r/a_0\\right)^{-1/2}-r/a_0\\right)$, where $r$ is the radius from the\ndrop center and $a_0$ is the initial outer radius. Under these conditions, the\ndeposited stain has a mountain-like morphology. Our framework can easily be\nextended to investigate new stain morphologies left by drying drops.",
        "positive": "On a recent very simple generalization of DMT theory of adhesion: As the interest in adhesion is shifting towards smaller and smaller scales,\nthe well known Tabor adhesion parameter decreases and the DMT theory is\nfrequently considered to be the appropriate limit. A very attractive much\nsimplified version of DMT has been proposed in a recent investigation of rough\ncontacts by Pastewka & Robbins (PNAS, 111(9), 3298-3303, 2014) which seems to\nwork in very general conditions in numerical experiments. However, when\ncomparing this calculation to the known theories for the sphere, surprisingly\nlarge conflicts occur, and the reason for the success of the numerical\nexperiments is obscure."
    },
    {
        "anchor": "Structural transitions of monoolein bicontinuous cubic phase induced by\n  inclusion of protein lysozyme solutions: Inclusion of protein lysozyme molecules in lipidic monoolein cubic phase\ninduces a transition from a $\\rm Pn\\bar{3}m$ structure to $\\rm Im\\bar{3}m$ one.\nSmall-angle X-ray scattering (SAXS) method with high intensity synchrotron\nradiation enabled us to follow closely the transition depending on the\nconditions of lysozyme solutions. We showed that concentrated lysozyme\nsolutions induced the appearance of the $\\rm Im\\bar{3}m$ structure coexisting\nwith the $\\rm Pn\\bar{3}m$ structure. From the relation between the lattice\nparameters of these two structures it was shown that they were related by the\nBonnet transformation of underlying triply periodic minimal surfaces. We found\nthat the transition also occurred at lower lysozyme concentration when NaCl\ninduced attraction between lysozyme molecules. The origin of the transition was\nconsidered as a frustration in the cubic phase where lysozyme molecules were\nhighly confined. A simple estimation of the frustration was given, which took\ninto account of the translational entropy of lysozyme molecules. At the highest\nconcentration of lysozyme and NaCl the $\\rm Im\\bar{3}m$ structure was found to\ndisappear and left only the $\\rm Pn\\bar{3}m$ structure. This was probably\neither due to the crystallization or phase separation of lysozyme solutions\nongoing microscopically, which absorbed lysozyme molecules from channels of the\ncubic phase and thus removed the frustration.",
        "positive": "Getting drowned in a swirl: deformable bead-spring model microswimmers\n  in external flow fields: Deformability is a central feature of many types of microswimmers, e.g. for\nartificially generated self-propelled droplets. Here, we analyze deformable\nbead-spring microswimmers in an externally imposed solvent flow field as simple\ntheoretical model systems. We focus on their behavior in a circular swirl flow\nin two spatial dimensions. Linear (straight) two-bead swimmers are found to\ncircle around the swirl with a slight drift to the outside with increasing\nactivity. In contrast to that, we observe for triangular three-bead or\nsquare-like four-bead swimmers a tendency of being drawn into the swirl and\nfinally getting drowned, although a radial inward component is absent in the\nflow field. During one cycle around the swirl, the self-propulsion direction of\nan active triangular or square-like swimmer remains almost constant, while\ntheir orbits become deformed exhibiting an ``egg-like'' shape. Over time, the\nswirl flow induces slight net rotations of these swimmer types, which leads to\nnet rotations of the egg-shaped orbits. Interestingly, in certain cases, the\norbital rotation changes sense when the swimmer approaches the flow\nsingularity. Our predictions can be verified in real-space experiments on\nartificial microswimmers."
    },
    {
        "anchor": "Measuring segregation characteristics of industrially relevant granular\n  mixtures: Part I -- A continuum model approach: We present a method to estimate the segregation parameter, $S,$ a key input\nin a continuum transport model of particulate flows. $S$ is determined by\nminimizing the difference between measured and model-predicted concentration\nprofiles. To validate the approach, we conduct discrete element method\nsimulations of size-bidisperse mixtures in quasi-2D bounded heap flow; the\nresulting data show that $S$ calculated from concentration profiles is\nconsistent with the directly measured value. The method's accuracy depends\ncritically on the velocity profile during filling, but only weakly on the\ndiffusion coefficient. When the velocity profile is nominally spanwise\ninvariant, the error between estimated and measured $S$ is $10\\%$. This method\nis intended for practical application (described in Part II), so we restrict\ncharacterization of the velocity profile to that which can be readily\ndetermined experimentally, and explore the sensitivity of concentration\nprofiles to variation of the gap between the sidewalls of the heap.",
        "positive": "Strand diffusion-limited closure of denaturation bubbles in DNA: The closure dynamics of a pre-equilibrated DNA denaturation bubble is studied\nusing both Brownian dynamics simulations and an analytical approach. The\nnumerical model consists of two semi-flexible interacting single strands\n(ssDNA) and a bending modulus which depends on the base-pair state, with\ndouble-strand DNA (dsDNA) segments being 50 times stiffer than ssDNA ones. For\nDNA lengths from N=20 to 100 base-pairs (bp) and initial bubble sizes of N-6\nbp, long closure times of 0.1 to 4 microseconds are found, following a scaling\nlaw in N^2.4. The bubble starts to close by a fast zipping which stops when the\nbubble reaches a highly bent metastable state of length around 10 bp. The\nlimiting final step to complete closure is controlled by the dsDNA \"arms\"\nrotational diffusion, with closure occurring once they are nearly aligned. The\ncentral role of chain bending, which cannot be accounted for in one-dimensional\nmodels, is thus illuminated."
    },
    {
        "anchor": "Softening Theory of Matter Tuning Atomic Border to Make Soft Materials: Regulation of material softness has both theoretical and practical\nsignificances due to irreplaceable applications of soft matter in rather\ndiverse areas. This article is dedicated to draft a theoretical category on\ninterpreting the mechanisms lying behind all soft matters, which can be termed\nas Softening Theory. A technical strategy with generalized purpose was proposed\nfor softening desired matter, i.e. the melting point of matter can be\nsignificantly reduced through tuning its interior boundaries in atomic level.\nThis theory accords well with the classical nuclear droplet model that treats\nthe nucleus as a droplet which had successfully explained many phenomena. It\nalso explained the experimental fact that, the material's melting point is\ndrastically reduced as the particles become smaller enough, in which situations\neffects of the atomic borders become much weaker. Along this direction, many\nphenomena existing in nature can be well understood. For example, if keeping in\nmind the fact that an atom consisting of nucleus and electronics can be\nregarded as fluid, all the matter consisted of atoms should maintain fluidic\nstate in their macroscopic scale, according to the consistency between macro\nand micro worlds. However, many substances just cannot remain their original\natomic fluidic behavior due to breaking of the consistency between macro and\nmicro states. Based on the current softening theory, it is now easy to\nunderstand that the breaking of such consistency is just caused due to\ngenerated forces from the atomic interactions. To resolve such intrinsic\nconfinement, a group of potential technical approaches can be developed to tune\nthe atomic borders of the matter and thus make desired soft materials. This\nwork provides a theoretical foundation to partially address the nature of the\nmaterial which will aid to make future soft matters in the coming time.",
        "positive": "Macroscopic current generated by local division and apoptosis in a\n  minimal model of tissue dynamics: We consider a minimal computational model of tissue dynamics with two active\ningredients: local particle division and apoptosis. We neglect other\nnon-equilibrium effects such as self-propulsion. We simulated the steady state\ndynamics inside an asymmetric channel and we found a net macroscopic current\nalong the channel. Although such macroscopic current in a similar geometry has\nbeen detected in swimming bacteria, our results showed that local division and\napoptosis are sufficient to generate a macroscopic current, without any need\nfor a self-propulsion/swimming mechanism. Our results might have applications\nin tissue engineering such as controlling tissue growth via a geometrically\nnon-uniform substrate."
    },
    {
        "anchor": "High-frequency dynamics of type-B glass formers investigated by\n  broadband dielectric spectroscopy: We present the results of broadband dielectric spectroscopy on two glass\nformers with strong Johari-Goldstein beta-relaxations. In addition to the\nalpha- and beta-relaxation dynamics, the extension of the spectra up to 1 THz\nalso allows revealing information on the fast beta-process in this class of\nmaterials. There is clear evidence for a fast process contributing in the\nregion of the high-frequency loss minimum, which is analyzed in terms of the\nidealized mode-coupling theory.",
        "positive": "Effective field theory approach to Casimir interactions on soft matter\n  surfaces: We utilize an effective field theory approach to calculate Casimir\ninteractions between objects bound to thermally fluctuating fluid surfaces or\ninterfaces. This approach circumvents the complicated constraints imposed by\nsuch objects on the functional integration measure by reverting to a point\nparticle representation. To capture the finite size effects, we perturb the\nHamiltonian by DH that encapsulates the particles' response to external fields.\nDH is systematically expanded in a series of terms, each of which scales\nhomogeneously in the two power counting parameters: \\lambda \\equiv R/r, the\nratio of the typical object size (R) to the typical distance between them (r),\nand delta=kB T/k, where k is the modulus characterizing the surface energy. The\ncoefficients of the terms in DH correspond to generalized polarizabilities and\nthus the formalism applies to rigid as well as deformable objects.\nSingularities induced by the point particle description can be dealt with using\nstandard renormalization techniques. We first illustrate and verify our\napproach by re-deriving known pair forces between circular objects bound to\nfilms or membranes. To demonstrate its efficiency and versatility, we then\nderive a number of new results: The triplet interactions present in these\nsystems, a higher order correction to the film interaction, and general scaling\nlaws for the leading order interaction valid for objects of arbitrary shape and\ninternal flexibility."
    },
    {
        "anchor": "Memory effects, arches and polar defect ordering at the cross-over from\n  wet to dry active nematics: We use analytic arguments and numerical solutions of the continuum, active\nnematohydrodynamic equations to study how friction alters the behaviour of\nactive nematics. Concentrating on the case where there is nematic ordering in\nthe passive limit, we show that, as the friction is increased, memory effects\nbecome more prominent and $+1/2$ topological defects leave increasingly\npersistent trails in the director field as they pass. The trails are\npreferential sites for defect formation and they tend to impose polar order on\nany new $+1/2$ defects. In the absence of noise and for high friction, it\nbecomes very difficult to create defects, but trails formed by any defects\npresent at the beginning of the simulations persist and organise into parallel\narch-like patterns in the director field. We show aligned arches of equal width\nare approximate steady state solutions of the equations of motion which\nco-exist with the nematic state. We compare our results to other models in the\nliterature, in particular dry systems with no hydrodynamics, where trails,\narches and polar defect ordering have also been observed.",
        "positive": "Network physics of attractive colloidal gels: Resilience, Rigidity, and\n  Phase Diagram: Attractive colloidal gels exhibit solid-like behavior at vanishingly small\nfractions of solids, owing to ramified space-spanning networks that form due to\nparticle-particle interactions. These networks give the gel its rigidity, and\nas the attraction between the particles grows, so does the elasticity of the\ncolloidal network formed. The emergence of this rigidity can be described\nthrough a mean field approach; nonetheless, fundamental understanding of how\nrigidity varies in gels of different attraction strengths is lacking. Moreover,\nrecovering an accurate gelation phase diagram based on the system's variables\nhave been an extremely challenging task. Understanding the nature of these\nfractal clusters, and how rigidity emerges from their connections is key to\ncontrolling and designing gels with desirable properties. Here, we employ\nwell-established concepts of network science to interrogate and characterize\nthe network of colloidal gels. We construct a particle-level network, having\nall the spatial coordinates of colloids with different attraction levels, and\nalso identify polydisperse rigid fractal clusters using a Gaussian Mixture\nModel, to form a coarse-grained cluster network that distinctly shows main\nphysical features of the colloidal gels. A simple mass-spring model then is\nused to recover quantitatively the elasticity of colloidal gels from these\ncluster networks. Interrogating the resilience of these gel networks show that\nthe elasticity of a gel (a dynamic property) is directly correlated to its\ncluster network's resilience (a static measure). Finally, we use the resilience\ninvestigations to devise [and experimentally validate] a fully resolved phase\ndiagram for colloidal gelation, with a clear solid-liquid phase boundary using\na single volume fraction of particles well beyond this phase boundary."
    },
    {
        "anchor": "Evaluating the robustness of top coatings comprising plasma-deposited\n  fluorocarbons in electrowetting systems: Thin dielectric stacks comprising a main insulating layer and a hydrophobic\ntop coating are commonly used in low voltage electrowetting systems. However,\nin most cases, thin dielectrics fail to endure persistent electrowetting\ntesting at high voltages, namely beyond the saturation onset, as electrolysis\nindicates dielectric failure. Careful sample inspection via optical microscopy\nrevealed possible local delamination of the top coating under high electric\nfields. Thus, improvement of the adhesion strength of the hydrophobic top\ncoating to the main dielectric is attempted through a plasma-deposited\nfluorocarbon interlayer. Interestingly enough the proposed dielectric stack\nexhibited a) resistance to dielectric breakdown, b) higher contact angle\nmodulation range, and c) electrowetting cycle reversibility. Appearance of\nelectrolysis in the saturation regime is inhibited, suggesting the use of this\nhydrophobic dielectric stack for the design of more efficient electrowetting\nsystems. The possible causes of the improved performance are investigated by\nnanoscratch characterization.",
        "positive": "Hydrodynamics of inelastic Maxwell models: An overview of recent results pertaining to the hydrodynamic description\n(both Newtonian and non-Newtonian) of granular gases described by the Boltzmann\nequation for inelastic Maxwell models is presented. The use of this\nmathematical model allows us to get exact results for different problems.\nFirst, the Navier--Stokes constitutive equations with explicit expressions for\nthe corresponding transport coefficients are derived by applying the\nChapman--Enskog method to inelastic gases. Second, the non-Newtonian\nrheological properties in the uniform shear flow (USF) are obtained in the\nsteady state as well as in the transient unsteady regime. Next, an exact\nsolution for a special class of Couette flows characterized by a uniform heat\nflux is worked out. This solution shares the same rheological properties as the\nUSF and, additionally, two generalized transport coefficients associated with\nthe heat flux vector can be identified. Finally, the problem of small spatial\nperturbations of the USF is analyzed with a Chapman--Enskog-like method and\ngeneralized (tensorial) transport coefficients are obtained."
    },
    {
        "anchor": "The hydrodynamics of slender swimmers near deformable interfaces: We study the coupled hydrodynamics between a motile slender microswimmer and\na deformable interface that separates two Newtonian fluid regions. From the\ndisturbance field generated by the swimming motion, we quantitatively\ncharacterize the interface deformation and the manner in which the coupling\nmodifies the microswimmer translation itself. We treat the role of the swimmer\ntype (pushers and pullers), size and model an interface that can deform due to\nboth surface tension and bending elasticity. Our analysis reveals a strong\ndependence of the hydrodynamics on the swimmer orientation and position. Given\nthe viscosities of the two fluid media, the interface properties and the\nswimmer type, a swimmer can either migrate towards or away from the interface\ndepending on its configurations. When the swimmer is oriented parallel to the\ninterface, a pusher-type swimmer is repelled from the interface at short times\nif it is swimming in the more viscous fluid. At long times however, pushers are\nalways attracted to the interface, and pullers are always repelled from it. On\nthe other hand, swimmers oriented orthogonal to the interface exhibit a\nmigration pattern opposite to the parallel swimmers. In consequence, a host of\ncomplex migration trajectories emerge for swimmers arbitrarily oriented to the\ninterface. We find that confining a swimmer between a rigid boundary and a\ndeformable interface results in regimes of attraction towards both surfaces\ndepending on the swimmer location in the channel, irrespective viscosity ratio.\nThe differing migration patterns are most prominent in a region of order the\nswimmer size from the interface, where the slender swimmer model yields a\nbetter approximation to the coupled hydrodynamics.",
        "positive": "Direct measurement of the critical pore size in a model membrane: We study pore nucleation in a model membrane system, a freestanding polymer\nfilm. Nucleated pores smaller than a critical size close, while pores larger\nthan the critical size grow. Holes of varying size were purposefully prepared\nin liquid polymer films, and their evolution in time was monitored using\noptical and atomic force microscopy to extract a critical radius. The critical\nradius scales linearly with film thickness for a homopolymer film. The results\nagree with a simple model which takes into account the energy cost due to\nsurface area at the edge of the pore. The energy cost at the edge of the pore\nis experimentally varied by using a lamellar-forming diblock copolymer\nmembrane. The underlying molecular architecture causes increased frustration at\nthe pore edge resulting in an enhanced cost of pore formation."
    },
    {
        "anchor": "The effects of rapid yawing on simple swimmer models and planar\n  Jeffery's orbits: Over a sufficiently long period of time, or from an appropriate distance, the\nmotion of many swimmers can appear smooth, with their trajectories appearing\nalmost ballistic in nature and slowly varying in character. These long-time\nbehaviours, however, often mask more complex dynamics, such as the side-to-side\nsnakelike motion exhibited by spermatozoa as they swim, propelled by the\nfrequent and periodic beating of their flagellum. Many models of motion neglect\nthese effects in favour of smoother long-term behaviours, which are often of\ngreater practical interest than the small-scale oscillatory motion. Whilst it\nmay be tempting to ignore any yawing motion, simply assuming that any effects\nof rapid oscillations cancel out over a period, a precise quantification of the\nimpacts of high-frequency yawing is lacking. In this study, we systematically\nevaluate the long-term effects of general high-frequency oscillations on\ntranslational and angular motion, cast in the context of microswimmers but\napplicable more generally. Via a multiple-scales asymptotic analysis, we show\nthat rapid oscillations can cause a long-term bias in the average direction of\nprogression. We identify sufficient conditions for an unbiased long-term effect\nof yawing, and we quantify how yawing modifies the speed of propulsion and the\neffective hydrodynamic shape when in shear flow. Furthermore, we investigate\nand justify the long-time validity of the derived leading-order solutions and,\nby direct computational simulation, we evidence the relevance of the presented\nresults to a canonical microswimmer.",
        "positive": "Local structure controls shear and bulk moduli in disordered solids: Paradigmatic model systems, which are used to study the mechanical response\nof matter, are random networks of point-atoms, random sphere packings, or\nsimple crystal lattices, all of these models assume central-force interactions\nbetween particles/atoms. Each of these models differs in the spatial\narrangement and the correlations among particles. In turn, this is reflected in\nthe widely different behaviours of the shear (G) and compression (K) elastic\nmoduli. The relation between the macroscopic elasticity as encoded in G, K and\ntheir ratio, and the microscopic lattice structure/order, is not understood. We\nprovide a quantitative analytical connection between the local orientational\norder and the elasticity in model amorphous solids with different internal\nmicrostructure, focusing on the two opposite limits of packings (strong\nexcluded-volume) and networks (no excluded-volume). The theory predicts that,\nin packings, the local orientational order due to excluded-volume causes less\nnonaffinity (less softness or larger stiffness) under compression than under\nshear. This leads to lower values of G/K, a well-documented phenomenon which\nwas lacking a microscopic explanation. The theory also provides an excellent\none-parameter description of the elasticity of compressed emulsions in\ncomparison with experimental data over a broad range of packing fractions."
    },
    {
        "anchor": "Twisting with a twist: supramolecular helix fluctuations in chiral\n  nematics: Most theoretical descriptions of lyotropic cholesteric liquid crystals to\ndate focus on homogeneous systems in which the rod concentration, as opposed to\nthe rod orientation, is uniform. In this work, we build upon the\nOnsager-Straley theory for twisted nematics and study the effect of weak\nconcentration gradients, generated by some external potential, on the\ncholesteric twist. We apply our theory to chiral nematics of nanohelices in\nwhich the supramolecular helix sense is known to spontaneously change sign upon\nvariation of particle concentration, passing through a so-called compensation\npoint at which the mesoscopic twist vanishes. We show that the imposed field\noffers exquisite control of the handedness and magnitude of the helicoidal\ndirector field, even at weak field strengths. Within the same framework we also\nquantify the director fluctuation spectrum and find evidence for a correlation\nlength diverging at the compensation point.",
        "positive": "Colloidal Hard Spheres: Triumphs, Challenges and Mysteries: The simplicity of hard spheres as a model system is deceptive. Although the\nparticles interact solely through volume exclusion, that nevertheless suffices\nfor a wealth of static and dynamical phenomena to emerge, making the model an\nimportant target for achieving a comprehensive understanding of matter. In\naddition, while real colloidal suspensions are typically governed by complex\ninteractions, Pusey and Van Megen [Nature 320 340--342 (1986)] demonstrated\nthat suitably tuned suspensions result in hard-sphere like behavior, thus\nbringing a valuable experimental complement to the celebrated theoretical\nmodel. Colloidal hard spheres are thus both a material in their own right and a\nplatform upon which phenomena exhibited by simple materials can be explored in\ngreat detail. These various purposes enable a particular synergy between\nexperiment, theory and computer simulation. Here we review the extensive body\nof work on hard spheres, ranging from their equilibrium properties such as\nphase behavior, interfaces and confinement to some of the non--equilibrium\nphenomena they exhibit such as sedimentation, glass formation and nucleation."
    },
    {
        "anchor": "Light Scattering by Cholesteric Skyrmions: We study the light scattering by localized quasi planar excitations of a\nCholesteric Liquid Crystal known as spherulites. Due to the anisotropic optical\nproperties of the medium and the peculiar shape of the excitations, we\nquantitatively evaluate the cross section of the axis-rotation of polarized\nlight. Because of the complexity of the system under consideration, first we\ngive a simplified, but analytical, description of the spherulite and we compare\nthe Born approximation results in this setting with those obtained by resorting\nto a numerical exact solution. The effects of changing values of the driving\nexternal static electric (or magnetic) field is considered. Possible\napplications of the phenomenon are envisaged.",
        "positive": "A one-dimensional model for elasto-capillary necking: We derive a non-linear one-dimensional (1d) strain gradient model predicting\nthe necking of soft elastic cylinders driven by surface tension, starting from\n3d finite-strain elasticity. It is asymptotically correct: the microscopic\ndisplacement is identified by an energy method. The 1d model can predict the\nbifurcations occurring in the solutions of the 3d elasticity problem when the\nsurface tension is increased, leading to a localization phenomenon akin to\nphase separation. Comparisons with finite-element simulations reveal that the\n1d model resolves the interface separating two phases accurately, including\nwell into the localized regime, and that it has a vastly larger domain of\nvalidity than 1d model proposed so far."
    },
    {
        "anchor": "Water confined in self-assembled ionic surfactants nano-structures: We present a coarse-grained model for ionic surfactants in explicit aqueous\nsolutions, and study by computer simulation both the impact of water content on\nthe morphology of the system, and the consequent effect of the formed\ninterfaces on the structural features of the adsorbed fluid. On increasing the\nhydration level at ambient conditions, the model exhibits a series of three\ndistinct phases: lamellar, cylindrical and micellar. We characterize the\ndifferent structures in terms of diffraction patterns and neutron scattering\nstatic structure factors. We demonstrate that the rate of variation of the\nnano-metric sizes of the self-assembled water domains shows peculiar changes in\nthe different phases. We also analyse in depth the structure of the\nwater/confining matrix interfaces, the implications of their tunable degree of\ncurvature, and the properties of water molecules in the different restricted\nenvironments. Finally, we discuss our results compared to experimental data and\ntheir impact on a wide range of important scientific and technological domains,\nwhere the behavior of water at the interface with soft materials is crucial.",
        "positive": "Fluid flow through packings of elastic shells: Fluid transport in porous materials is commonly studied in geological samples\n(soil, sediments etc.) or idealized systems, but the fluid flow through\ncompacted granular materials, consisting of substantially strained granules,\nremains relatively unexplored. As a step towards filling this gap, we study a\nmodel of liquid transport in packings of deformable elastic shells using Finite\nElement and Lattice-Boltzmann methods. We find that the fluid flow abruptly\nvanishes as the porosity of the material falls below a critical value, and the\nflow obstruction exhibits features of a percolation transition. We further show\nthat the fluid flow can be captured by a simplified permeability model in which\nthe complex porous material is replaced by a collection of disordered\ncapillaries, which are distributed and shaped by the percolation transition. To\nthat end, we numerically explore the divergence of hydraulic tortuosity\n$\\rm\\tau_H$ and the decrease of a hydraulic radius $\\rm R_h$ as the percolation\nthreshold is approached. We interpret our results in terms of scaling\npredictions derived from the percolation theory applied to random packings of\nspheres."
    },
    {
        "anchor": "Tessellated granular metamaterials with tunable elastic moduli: Most granular packings possess shear moduli ($G$) that increase with the\napplied external pressure, and bulk moduli ($B$) that increase or remain\nconstant with pressure. This paper presents \"tessellated\" granular\nmetamaterials for which both $G$ and the ratio $G/B$ decrease with increasing\npressure. The granular metamaterials are made from flexible tessellations\nforming a ring of closed cells, each containing a small number of solid\nparticles. For under-constrained tessellations, the dominant contributions to\n$G$ and $B$ are the particle-particle and particle-cell interactions. With\nspecific particle configurations in the cells, we limit the number of possible\nparticle rearrangements to achieve decreasing $G$ as we increase the pressure\ndifference between the inside and outside of the tessellation, leading to $G/B\n\\ll 1$ at large pressures. We further study tessellated granular metamaterials\nwith cells containing a single particle and many particles to determine the\nvariables that control the mechanical response of particle-filled tessellations\nas a function of pressure.",
        "positive": "Dynamics of a sheared twist bend nematic liquid crystal: We study the flow behaviour of a twist-bend nematic $(N_{TB})$ liquid\ncrystal. It shows three distinct shear stress ($\\sigma$) responses in a certain\nrange of temperatures and shear rates ($\\dot{\\gamma}$). In Region-I,\n$\\sigma\\sim\\sqrt{\\dot{\\gamma}}$, in region-II, the stress shows a plateau,\ncharacterised by a power law $\\sigma\\sim{\\dot{\\gamma}}^{\\alpha}$, where\n$\\alpha\\sim0.1-0.4$ and in region-III, $\\sigma\\sim\\dot{\\gamma}$. With\nincreasing shear rate, $\\sigma$ changes continuously from region-I to II,\nwhereas it changes discontinuously with a hysteresis from region-II to III. In\nthe plateau (region-II), we observe a dynamic stress fluctuations, exhibiting\nregular, periodic and quasiperiodic oscillations under the application of\nsteady shear. The observed spatiotemporal dynamics in our experiments are close\nto those were predicted theoretically in sheared nematogenic fluids."
    },
    {
        "anchor": "Organized condensation of worm-like chains: We present results relevant to the equilibrium organization of DNA strands of\narbitrary length interacting with a spherical organizing center, suggestive of\nDNA-histone complexation in nucleosomes. We obtain a rich phase diagram in\nwhich a wrapping state is transformed into a complex multi-leafed, rosette\nstructure as the adhesion energy is reduced. The statistical mechanics of the\n\"melting\" of a rosette can be mapped into an exactly soluble one-dimensional\nmany-body problem.",
        "positive": "Equivalent circuit and continuum modeling of the impedance of\n  electrolyte-filled pores: Batteries, supercapacitors, and several other electrochemical devices charge\nby accumulating ions in the pores of electrolyte-immersed porous electrodes.\nThe charging of such devices has long been interpreted using equivalent\ncircuits and the partial differential equations these give rise to. Here, we\ndiscuss the validity of the transmission line (TL) circuit and equation for\nmodeling a single electrolyte-filled pore in contact with a reservoir of\nresistance $R_{r}$. The textbook derivation of the pore-reservoir impedance\n$R_r+Z_p$ from the TL equation does not correctly account for ionic current\nconservation at the pore-reservoir interface. However, correcting this\nshortcoming leads to the same impedance. We also show that the pore impedance\n$Z_p$ can be derived directly from the TL circuit, bypassing the TL equation\ncompletely. The TL circuit assumes equipotential lines in an electrolyte-filled\npore to be straight, which is not the case near the pore entrance and end. To\ndetermine the importance of these regions, we numerically simulated the\ncharging of pores of different lengths $\\ell_p$ and radii $\\varrho_p$ through\nthe Poisson-Nernst-Planck equations. We find that pores with aspect ratios\nbeyond $\\ell_p/\\varrho_p\\gtrapprox5$ have impedances in good agreement with\n$Z_p$."
    },
    {
        "anchor": "Modified conformation and physical properties in conducting polymers due\n  to varying conjugation and solvent interactions: Small angle X-ray scattering (SAXS) studies in\npoly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) with\nvarying conjugation, and polyethylene dioxythiophene complexed with polystyrene\nsulfonate (PEDOT-PSS) in different solvents have shown the important role of\npi-electron conjugation and solvent-chain interactions in controlling the chain\nconformation and assembly. In MEH-PPV, by increasing the extent of conjugation\nfrom 30 to 100 %, the persistence length (l_p) increases from 20 to 66\nAngstrom. Moreover, a pronounced second peak in the pair distribution function\nhas been observed in fully conjugated chain, at larger length scales. This\nfeature indicates that the chain segments tend to self-assemble as the\nconjugation along the chain increases. In case of PEDOT-PSS, the chains undergo\nsolvent induced expansion and enhanced chain organization. The clusters formed\nby chains are better correlated in dimethyl sulfoxide (DMSO) solution than\nwater, as observed in the scattered intensity profiles. The values of radius of\ngyration and the exponent (water: 2.6, DMSO: 2.31) of power-law decay, obtained\nfrom the unified scattering function (Beaucage) analysis, give evidence for\nchain expansion from compact (in water) to extended coil in DMSO solutions,\nwhich is consistent with the Kratky plot analysis. The mechanism of this\ntransition and the increase in dc conductivity of PEDOT-PSS in DMSO solution\nare discussed. The onset frequency for the increase in ac conduction as well as\nits temperature dependence probes the extent of connectivity in PEDOT-PSS\nsystem. The enhanced charge transport in PEDOT-PSS in DMSO is attributed to the\nextended chain conformation as observed in SAXS results.",
        "positive": "Study of thickness dependent density in ultrathin water soluble polymer\n  films: Density of the polyacrylamide ultrathin films has been studied using X-ray\nreflectivity technique. Two sources (one powder and another aqueous solution)\nof polyacrylamide were used to prepare spin coated films on silicon substrate.\nLight scattering measurements show that the polymer chains were unentangled in\na concentrated (4 mg/ml) as well as in a dilute (2 mg/ml) solution prepared\nfrom the powder, whereas the solution (4 mg/ml) prepared by diluting the\nsolution source shows entangled chain morphology. Three sets of films of\ndifferent thicknesses were prepared using the three solutions by spin coating\non silicon substrates. Comparison of X-ray reflectivity data for as prepared\nand dry films reveals that the shrinkage of the films decreases with increasing\nthickness. Average electron densities of the films were found to follow a trend\nof higher density for thinner films with a maximum increase of about 12%\ncompared to the bulk. The densities of all the films irrespective of the nature\nof entanglement and concentration of their source were found to increase with\nspin speed of coating and attain saturation at higher speed. Absence of\ncorrelation between shrinkage and density data and the fact that the densities\nof all the films follow a master curve irrespective of their origin suggest\nthat the higher density of the films result from the higher orientation of\nchains as a consequence of an interplay between stretching and stronger\nattractive interactions of polar nature."
    },
    {
        "anchor": "Interaction of multiple particles with a solidification front : from\n  compacted particle layer to particle trapping: The interaction of solidification fronts with objects such as particles,\ndroplets, cells, or bubbles is a phenomenon with many natural and technological\noccurrences. For an object facing the front, it may yield various fates, from\ntrapping to rejection, with large implications regarding the solidification\npattern. However, whereas most situations involve multiple particles\ninteracting with each other and the front, attention has focused almost\nexclusively on the interaction of a single, isolated object with the front.\nHere we address experimentally the interaction of multiple particles with a\nsolidification front by performing solidification experiments of a monodisperse\nparticle suspension in a Hele-Shaw cell, with precise control of growth\nconditions and real-time visualization. We evidence the growth of a particle\nlayer ahead of the front at a close-packing volume fraction and we document its\nsteady state value at various solidification velocities. We then extend single\nparticle models to the situation of multiple particles by taking into account\nthe additional force induced on an entering particle by viscous friction in the\ncompacted particle layer. By a force balance model, this provides an indirect\nmeasure of the repelling mean thermomolecular pressure over a particle entering\nthe front. The presence of multiple particles is found to increase it following\na reduction of the thickness of the thin liquid film that separates particles\nand front. We anticipate the findings reported here to provide a relevant basis\nto understand many complex solidification situations in geophysics,\nengineering, biology, or food engineering, where multiple objects interact with\nthe front and control the resulting solidification patterns.",
        "positive": "A viscous froth model adapted to wet foams: We describe the extension of a \"viscous froth\" model to the dynamics of a wet\nfoam in a Hele-Shaw cell. The two-dimensional model includes the friction\nexperienced by the soap films as they are dragged along the cell walls, while\nretaining accurate geometrical information. To explore the consequences of\nchanging the liquid content in this situation, we consider a simple foam\ngeometry known as a bubble lens: a bubble partially filling a narrow, straight\nchannel with a single film spanning the gap between the bubble and the opposite\nwall. The triple vertices of this structure are decorated with Plateau borders\nwhose area determines the liquid fraction of the foam.\n  We derive new expressions to allow the pressure in the Plateau borders to be\ncalculated, and determine numerically the range of driving velocities for which\nthe system reaches a steady state. As the liquid fraction increases, the lens\nmoves more slowly and the spanning film is more greatly distorted, reducing the\nrange of stable driving velocities. For higher velocities, the spanning film\nmoves so quickly that it leaves the bubble behind, a situation which must be\navoided in any particular application."
    },
    {
        "anchor": "Coarse-graining dynamics by telescoping down time-scales: comment for\n  Faraday FD144: I briefly review some concepts related to coarse-graining methods for the\ndynamics of soft matter systems and argue that such schemes will almost always\nneed to telescope down the physical hierarchy of time-scales to a more\ncompressed, but more computationally manageable, separation.",
        "positive": "Conservation-Dissipation Formalism for Soft Matter Physics: II.\n  Application to Non-isothermal Nematic Liquid Crystals: To most existing non-equilibrium theories, the modeling of non-isothermal\nprocesses was a hard task. Intrinsic difficulties involved the non-equilibrium\ntemperature, the coexistence of conserved energy and dissipative entropy, etc.\nIn this paper, by taking the non-isothermal flow of nematic liquid crystals as\na typical example, we illustrated that thermodynamically consistent models in\neither vectorial or tensorial forms could be constructed within the framework\nof Conservation-Dissipation Formalism (CDF). And the classical isothermal\nEricksen-Leslie model and Qian-Sheng model were shown to be special cases of\nour new vectorial and tensorial models in the isothermal, incompressible and\nstationary limit. Most importantly, from above examples, it was learnt that\nmathematical modeling based on CDF could easily solve the issues relating with\nnon-isothermal situations in a systematic way. The first and second laws of\nthermodynamics were satisfied simultaneously. The non-equilibrium temperature\nwas defined self-consistently through the partial derivative of entropy\nfunction. Relaxation-type constitutive relations were constructed, which gave\nrise to the classical linear constitutive relations, like Newton's law and\nFourier's law, in stationary limits. Therefore, CDF was expected to have a\nbroad scope of applications in soft matter physics, especially under the\ncomplicated situations, such as non-isothermal, compressible and nanoscale\nsystems."
    },
    {
        "anchor": "Influence of polydispersity on micromechanics of granular materials: We study the effect of polydispersity on the macroscopic physical properties\nof granular packings in two and three dimensions. A mean-field approach is\ndeveloped to approximate the macroscale quantities as functions of the\nmicroscopic ones. We show that the trace of the fabric and stress tensors are\nproportional to the mean packing properties (e.g. packing fraction, average\ncoordination number, and average normal force) and dimensionless correction\nfactors, which depend only on the moments of the particle-size distribution.\nSimilar results are obtained for the elements of the stiffness tensor of\nisotropic packings in the linear affine response regime. Our theoretical\npredictions are in good agreement with the simulation results.",
        "positive": "Curvature sensing of curvature-inducing proteins with internal structure: Many types of peripheral and transmembrane proteins can sense and generate\nmembrane curvature. Laterally isotropic proteins and crescent proteins with\ntwofold rotational symmetry, such as Bin/Amphiphysin/Rvs superfamily proteins,\nhave been studied theoretically. However, proteins often have an asymmetric\nstructure or a higher rotational symmetry. We theoretically studied the\ncurvature sensing of proteins with asymmetric structures and structural\ndeformations. First, we examined proteins consisting of two rod-like segments.\nWhen proteins have mirror symmetry, their sensing ability is similar to that of\nsingle-rod proteins; hence, with increasing protein density on a cylindrical\nmembrane tube, a second- or first-order transition occurs at a middle or small\ntube radius, respectively. As asymmetry is introduced, this transition becomes\na continuous change, and metastable states appear at high protein densities.\nProtein with threefold, fivefold, or higher rotational symmetry has laterally\nisotropic bending energy. However, when a structural deformation is allowed,\nthe protein can have a preferred orientation and stronger curvature sensing."
    },
    {
        "anchor": "Life and death of not so \"bare\" bubbles: In this paper, we investigate how the drainage and rupture of\nsurfactant-stabilised bubbles floating at the surface of a liquid pool depend\non the concentration of surface-active molecules in water. Drainage\nmeasurements at the apex of bubbles indicate that the flow profile is\nincreasingly plug-like as the surfactant concentration is decreased from\nseveral times the critical micellar concentration (cmc) to just below the cmc.\nHigh-speed observations of bubble bursting reveal that the position at which a\nhole nucleates in the bubble cap also depends on the surfactant concentration.\nOn average, the rupture is initiated close to the bubble foot for low\nconcentrations (< cmc) while its locus moves towards the top of the bubble cap\nas the concentration increases above the cmc. In order to explain this\ntransition, we propose that marginal regeneration may be responsible for bubble\nrupture at low concentrations but that bursting at the apex for higher\nconcentrations is driven by gravitational drainage.",
        "positive": "Nonequilibrium Fluctuations in Sedimenting Suspensions: A Dynamical\n  Renormalization Group Theory: A nonlinear two-fluid stochastic hydrodynamical description of velocity and\nconcentration fluctuations in sedimenting suspensions is constructed, and\nanalyzed using self-consistent (SC) and renormalization group (RG) methods. The\nadvection of particles by velocity fluctuations is shown to be ``relevant'' in\nall dimensions $d < 6$ . Both RG and SC analyses predict a strong reduction in\nthe dependence of velocity fluctuations on system-size $L$ relative to the\n$L^{1/2}$ obtained in the linearized theory of Caflisch and Luke [Phys. Fluids\n{\\bf 28}, 785 (1985)]. This is an important step towards resolving a ten-year\nold puzzle in the field."
    },
    {
        "anchor": "Linear Response for Granular Fluids: The linear response of an isolated, homogeneous granular fluid to small\nspatial perturbations is studied by methods of non-equilibrium statistical\nmechanics. The long wavelength linear hydrodynamic equations are obtained, with\nformally exact expressions for the susceptibilities and transport coefficients.\nThe latter are given in equivalent Einstein-Helfand and Green-Kubo forms. The\ncontext of these results and their contrast with corresponding results for\nnormal fluids are discussed.",
        "positive": "Percolation of particles on recursive lattices: (II) the effect of size\n  and shape disparities: The preparation of many composites requires the intermixing of several\nmacromolecular fluids along with the addition of solid filler particles. These\nfillers are usuallly polydisperse and there is an extensive experimental\nevidence that their size and shape profoundly affects the properties of the\nresulting material. In particular, it is generally found that the percolation\nthreshold decreases as the size disparity between the different particles\npresent in a system increases and that the threshold decreases with the aspect\nratio of the particles. Here a recursive approach that we have recently\nintroduced is applied to the study of the percolation of particles of different\nsizes and shapes, without the presence of a polymer matrix, on a lattice in\nvarious phases including metastable states. In our approach the original\nlattice is replaced by a recursive structure on which calculations are done\nexactly and interactions as well as size and shape disparities can be easily\ntaken into account In the previous paper we have introduced the recursive\napproach and shown how correlations among particles of the same size can affect\npercolation. Before considering the complete system made of particles of\nvarious sizes and shapes embedded in a polymer matrix here we describe the\nproperties of systems made of particles without any matrix. The approach\nappears to be extremely successful since it is able to capture most of the\nimportant features observed in experiments."
    },
    {
        "anchor": "Surfactant Driven Fracture of Interfacial Particle Rafts: We investigate the dynamic fracture of a close-packed monolayer of particles,\nor particle raft, floating at a liquid-gas interface induced by the localised\naddition of surfactant. Unusually for a two-dimensional solid, our experiments\nshow that the speed of crack propagation here is not affected by the elastic\nproperties of the raft. Instead it is controlled by the rate at which\nsurfactant is advected to the crack tip by means of the induced Marangoni\nflows. Further, the velocity of propagation is not constant in time and the\nlength of the crack scales as $t^{3/4}$. More broadly, this surfactant induced\nrupture of interfacial rafts suggests ways to manipulate them for applications.",
        "positive": "Beating the teapot effect: We investigate the dripping of liquids around solid surfaces in the regime of\ninertial flows, a situation commonly encountered with the so-called \"teapot\neffect\". We demonstrate that surface wettability is an unexpected key factor in\ncontrolling flow separation and dripping, the latter being completely\nsuppressed in the limit of superhydrophobic substrates. This unforeseen\ncoupling is rationalized in terms of a novel hydro-capillary adhesion\nframework, which couples inertial flows to surface wettability effects. This\ndescription of flow separation successfully captures the observed dependence on\nthe various experimental parameters - wettability, flow velocity, solid surface\nedge curvature-. As a further illustration of this coupling, a real-time\ncontrol of dripping is demonstrated using electro-wetting for contact angle\nactuation."
    },
    {
        "anchor": "Deposition Morphology of Granular Column Collapses: Granular column collapses result in an array of flow phenomena and deposition\nmorphologies, the understanding of which brings insights into studying granular\nflows in both natural and engineering systems. Guided by experiments, we\ncarried out computational studies with the discrete element method (DEM) to\nidentify fundamental links between the macro-scale behavior and micro-scale\nproperties of granular columns. A physics-based non-dimensional number\ncombining particle and bulk properties of the column, $\\alpha_{\\textrm{eff}}$,\nwas found to determinate three collapse regimes (quasi-static, inertial, and\nliquid-like), revealing universal trends of flow regimes and deposition\nmorphologies under different conditions. This non-dimensional number represents\nphysically the competing inertial and frictional effects that govern the\nbehavior of the granular column collapse, including energy conversion and\ndissipation. The finding is important for understanding quantitatively the flow\nof granular materials and their deposits.",
        "positive": "The coherent motions of thermal active Brownian particles: Active matter exhibits many intriguing non-equilibrium character,\n\\emph{e.g.}, the active Brownian particles (ABP) without any attractive and\naligned interactions can occur the mobility-induced phase transition to form\nsome dense domains with both the structural ordering and dynamical coherence.\nRecently, the velocity correlation among the particles in the dense and ordered\nclusters was found in athermal ABP systems, however, seemed to disappear if\nincluding the thermal noises to describe microscopic ABPs, bringing some\nconfusion about the generality of the consistence between structure and\ndynamics in ABPs. Here we demonstrate that the thermal noises imposing a large\nrandom term on the instantaneous velocity of ABPs hinder the observation of the\n(small) correlation in motions of ABPs. By averaging the instantaneous velocity\n(or equivalently, calculating the displacement) in various lag times, we show\nthat the motions of thermal-fluctuated ABPs in the one order of magnitude\nsmaller than the translational characteristic time are highly coherent and\nconsistent spatially with the structural ordering of the ABPs."
    },
    {
        "anchor": "Accurate modeling approach for the structural comparison between\n  monolayer polymer tubes and single-walled nanotubes: In a recent computational study, we found highly structured ground states for\ncoarse-grained polymers adsorbed to ultrathin nanowires in a certain model\nparameter region. Those tubelike configurations show, even at a first glance,\nexciting morphological similarities to known atomistic nanotubes such as\nsingle-walled carbon nanotubes. In order to explain those similarities in a\nsystematic way, we performed additional detailed and extensive simulations of\ncoarse-grained polymer models with various parameter settings.\n  We show this here and explain why standard geometrical models for atomistic\nnanotubes are not suited to interpret the results of those studies. In fact,\nthe general structural behavior of polymer nanotubes, as well as specific\nprevious observations, can only be explained by applying recently developed\npolyhedral tube models.",
        "positive": "Kovacs effect and the relation between glasses and supercooled liquids: In this note we revisit the Kovacs effect, concerning the way in which the\nvolume of a glass-forming liquid, which has been driven out of equilibrium,\nchanges with time while the system evolves towards a metastable state. The\ntheoret- ical explanation of this phenomenon has attracted much interest even\nin recent years, because of its relation with some subtle aspects of the still\nelusive nature of the glass transition. In fact, even if there is a rather\ngeneral consensus on the fact that what is experimentally observed on cooling\nis the dramatic effect produced by the dynam- ical arrest of slower degrees of\nfreedom over the experimental time scale, it is not yet clear whether this\nphenomenology can be justified upon assuming the existence of an underlying\n(possibly, high order) phase transition at lower temperatures."
    },
    {
        "anchor": "Spurious violation of the Stokes-Einstein-Debye relation in supercooled\n  water: The theories of Brownian motion, the Debye rotational diffusion model, and\nhydrodynamics together provide us with the Stokes--Einstein--Debye (SED)\nrelation between the rotational relaxation time of the $\\ell$-th degree\nLegendre polynomials $\\tau_\\ell$, and viscosity divided by temperature,\n$\\eta/T$. Experiments on supercooled liquids are frequently performed to\nmeasure the SED relations, $\\tau_{\\ell}k_{\\rm B}T/\\eta$ and $D_{\\rm\nt}\\tau_{\\ell}$, where $D_{\\rm t}$ is the translational diffusion constant.\nHowever, the SED relations break down, and its molecular origin remains\nelusive. Here, we assess the validity of the SED relations in TIP4P/2005\nsupercooled water using molecular dynamics simulations. Specifically, we\ndemonstrate that the higher-order $\\tau_\\ell$ values exhibit a temperature\ndependence similar to that of $\\eta/T$, whereas the lowest-order $\\tau_\\ell$\nvalues are decoupled with $\\eta/T$, but are coupled with the translational\ndiffusion constant. We reveal that the SED relations are so spurious that they\nsignificantly depend on the degree of Legendre polynomials.",
        "positive": "Sedimentation of a Colloidal Monolayer Down an Inclined Plane: We study the driven collective dynamics of a colloidal monolayer\nsedimentating down an inclined plane. The action of the gravity force parallel\nto the bottom wall creates a flow around each colloid, and the hydrodynamic\ninteractions among the colloids accelerate the sedimentation as the local\ndensity increases. This leads to the creation of a universal \"triangular\"\ninhomogeneous density profile, with a traveling density shock at the leading\nfront moving in the downhill direction. Unlike density shocks in a colloidal\nmonolayer driven by applied torques rather than forces [Phys. Rev. Fluids,\n2(9):092301, 2017], the density front during sedimentation remains stable over\nlong periods of time even though it develops a roughness on the order of tens\nof particle diameters. Through experimental measurements and particle-based\ncomputer simulations, we find that the Burgers equation can model the density\nprofile along the sedimentation direction as a function of time remarkably\nwell, with a modest improvement if the nonlinear conservation law accounts for\nthe sub-linear dependence of the collective sedimentation velocity on density."
    },
    {
        "anchor": "Packing of elastic wires in flexible shells: The packing problem of long thin filaments that are injected into confined\nspaces is of fundamental interest for physicists and biologists alike. How\nlinear threads pack and coil is well known only for the ideal case of rigid\ncontainers, though. Here, we force long elastic rods into flexible spatial\nconfinement borne by an elastic shell to examine under which conditions\nrecently acquired knowledge on wire packing in rigid spheres breaks down. We\nfind that unlike in rigid cavities, friction plays a key role by giving rise to\nthe emergence of two distinct packing patterns. At low friction, the wire\ndensely coils into an ordered toroidal bundle with semi-ellipsoidal\ncross-section, while at high friction, it packs into a highly disordered,\nhierarchic structure. These two morphologies are shown to be separated by a\ncontinuous phase transition. Our findings demonstrate the dramatic impact of\nfriction and confinement elasticity on filamentous packing and might drive\nfuture research on such systems in physics, biology and even medical technology\ntoward including these mutually interacting effects.",
        "positive": "Translation-Rotation Coupling in the Dynamics of Linear Molecules in\n  Water: We study by computer simulations the coupled rotational and translational\ndynamics of three important linear diatomic molecules, namely, carbon monoxide\n(CO), nitric oxide (NO) and cyanide ion (CN-) in water. Translational diffusion\nof these molecules is found to be strongly coupled to their own rotational\ndynamics which in turn are coupled to similar motions of surrounding water. We\nexamined the validity of hydrodynamic predictions and found them to be largely\ninsufficient, particularly for rotational diffusion. A mode coupling theory\napproach is developed and applied to understand the complexity of\ntranslation-rotation coupling."
    },
    {
        "anchor": "Influence of Rigidity and Knot Complexity on the Knotting of Confined\n  Polymers: We employ computer simulations and thermodynamic integration to analyse the\neffects of bending rigidity and slit confinement on the free energy cost of\ntying knots, $\\Delta F_{\\rm knotting}$, on polymer chains under tension. A\ntension-dependent, non-zero optimal stiffness $\\kappa_{\\rm min}$ exists, for\nwhich $\\Delta F_{\\rm knotting}$ is minimal. For a polymer chain with several\nstiffness domains, each containing a large amount of monomers, the domain with\nstiffness $\\kappa_{\\rm min}$ will be preferred by the knot. A {\\it local}\nanalysis of the bending in the interior of the knot reveals that local\nstretching of chains at the braid region is responsible for the fact that the\ntension-dependent optimal stiffness has a non-zero value. The reduction in\n$\\Delta F_{\\rm knotting}$ for a chain with optimal stiffness relative to the\nflexible chain can be enhanced by tuning the slit width of the 2D confinement\nand increasing the knot complexity. The optimal stiffness itself is independent\nof the knot types we considered, while confinement shifts it towards lower\nvalues.",
        "positive": "Gate Electrodes Enable Tunable Nanofluidic Particle Traps: The ability to control the location of nanoscale objects in liquids is\nessential for fundamental and applied research from nanofluidics to molecular\nbiology. To overcome their random Brownian motion, the electrostatic fluidic\ntrap creates local minima in potential energy by shaping electrostatic\ninteractions with a tailored wall topography. However, this strategy is\ninherently static -- once fabricated the potential wells cannot be modulated.\nHere, we propose and experimentally demonstrate that such a trap can be\ncontrolled through a buried gate electrode.We measure changes in the average\nescape times of nanoparticles from the traps to quantify the induced\nmodulations of $0.7k_\\rm{B}T$ in potential energy and 50 mV in surface\npotential. Finally, we summarize the mechanism in a parameter-free predictive\nmodel, including surface chemistry and electrostatic fringing, that reproduces\nthe experimental results. Our findings open a route towards real-time\ncontrollable nanoparticle traps."
    },
    {
        "anchor": "Geometric pinning and antimixing in scaffolded lipid vesicles: Unravelling the physical mechanisms behind the organisation of lipid domains\nis a central goal in cell biology and membrane biophysics. Previous studies on\ncells and model lipid bilayers featuring phase-separated domains found an\nintricate interplay between the membrane geometry and its chemical composition.\nHowever, the lack of a model system with simultaneous control over the membrane\nshape and conservation of its composition precluded a fundamental understanding\nof curvature-induced effects. Here, we present a new class of multicomponent\nvesicles supported by colloidal scaffolds of designed shape. We find that the\ndomain composition adapts to the geometry, giving rise to a novel \"antimixed\"\nstate. Theoretical modelling allowed us to link the pinning of domains by\nregions of high curvature to the material parameters of the membrane. Our\nresults provide key insights into the phase separation of cellular membranes\nand on curved surfaces in general.",
        "positive": "Role of cilia activity and surrounding viscous fluid on properties of\n  metachronal waves: Large groups of active cilia collectively beat in a fluid medium as\nmetachronal waves, essential for some microorganisms motility and for flow\ngeneration in mucociliary clearance. Several models can predict the emergence\nof metachronal waves, but what controls the properties of metachronal waves is\nstill unclear. Here, we investigate numerically a simple model for cilia in the\npresence of noise on regular lattices in one- and two-dimensions. We\ncharacterize the wave using spatial correlation and the frequency of collective\nbeating. Our results clearly show that the viscosity of the fluid medium does\nnot affect the wavelength; the activity of the cilia does. These numerical\nresults are supported by a dimensional analysis, which is expected to be robust\nagainst the model for active force generation, unless surrounding fluid\ninfluences the cilia activity. Interestingly, enhancement of cilia activity\nincreases the wavelength and decreases the beating frequency, keeping the wave\nvelocity almost unchanged. These results might have significance in\nunderstanding paramecium locomotion and mucociliary clearance diseases."
    },
    {
        "anchor": "DNA unzipped under a constant force exhibits multiple metastable\n  intermediates: Single molecule studies, at constant force, of the separation of\ndouble-stranded DNA into two separated single strands may provide information\nrelevant to the dynamics of DNA replication. At constant applied force, theory\npredicts that the unzipped length as a function of time is characterized by\njumps during which the strands separate rapidly, followed by long pauses where\nthe number of separated base pairs remains constant. Here, we report previously\nuncharacterized observations of this striking behavior carried out on a number\nof identical single molecules simultaneously. When several single lphage\nmolecules are subject to the same applied force, the pause positions are\nreproducible in each. This reproducibility shows that the positions and\ndurations of the pauses in unzipping provide a sequence-dependent molecular\nfingerprint. For small forces, the DNA remains in a partially unzipped state\nfor at least several hours. For larger forces, the separation is still\ncharacterized by jumps and pauses, but the double-stranded DNA will completely\nunzip in less than 30 min.",
        "positive": "Gas pressure in bubble attached to tube circular outlet: In the present Supplementary notes to our work \"Arresting bubble coarsening:\nA two-bubble experiment to investigate grain growth in presence of surface\nelasticity\" (accepted in EPL), we derive the expression of the gas pressure\ninside a bubble located above and attached to the circular outlet of a vertical\ntube."
    },
    {
        "anchor": "Sequencing of semiflexible polymers of varying bending rigidity using\n  patterned pores: We study the translocation of a semiflexible polymer through extended pores\nwith patterned stickiness, using Langevin dynamics simulations. We find that\nthe consequence of pore patterning on the translocation time dynamics is\ndramatic and depends strongly on the interplay of polymer stiffness and\npore-polymer interactions. For heterogeneous polymers with periodically varying\nstiffness along their lengths, we find that variation of the block size of the\nsequences and the orientation, results in large variations in the translocation\ntime distributions. We show how this fact may be utilized to develop an\neffective sequencing strategy. This strategy involving multiple pores with\npatterned surface energetics, can predict heteropolymer sequences having\ndifferent bending rigidity to a high degree of accuracy.",
        "positive": "General theory of charge regulation and surface capacitance: A generalization of the mean-field approach will be derived that will take\ninto account the ion-ion as well as ion-surface non-electrostatic effects on an\nequal footing, being based on the bulk and surface equations of state in the\nabsence of electrostatic interactions. This approach will be applied to the\ncalculation of the differential capacitance for several models of the specific\nion-surface non-electrostatic interactions providing a thermodynamic insight\ninto the characteristics of the differential capacitance. The packing\nconsiderations due to surface adsorbed ions will be shown to be more relevant\nthen the bulk packing constraints for ions vicinal to the surface, and to set\nin prior to the conditions where the bulk packing constraints would become\nrelevant."
    },
    {
        "anchor": "Theoretical prediction of free-energy landscapes for complex\n  self-assembly: We present a technique for calculating free-energy profiles for the\nnucleation of multicomponent structures that contain as many species as\nbuilding blocks. We find that a key factor is the topology of the graph\ndescribing the connectivity of the target assembly. By considering the designed\ninteractions separately from weaker, incidental interactions, our approach\nyields predictions for the equilibrium yield and nucleation barriers. These\npredictions are in good agreement with corresponding Monte Carlo simulations.\nWe show that a few fundamental properties of the connectivity graph determine\nthe most prominent features of the assembly thermodynamics. Surprisingly, we\nfind that polydispersity in the strengths of the designed interactions\nstabilizes intermediate structures and can be used to sculpt the free-energy\nlandscape for self-assembly. Finally, we demonstrate that weak incidental\ninteractions can preclude assembly at equilibrium due to the combinatorial\npossibilities for incorrect association.",
        "positive": "Multi-valued inverse design: multiple surface geometries from one flat\n  sheet: Designing flat sheets that can be made to deform into 3D shapes is an area of\nintense research with applications in micromachines, soft robotics, and medical\nimplants. Thus far, such sheets were designed to adopt a single target shape.\nHere, we show that through anisotropic deformation applied inhomogenously\nthroughout a sheet, it is possible to design a single sheet that can deform\ninto multiple surface geometries upon different actuations. The key to our\napproach is development of an analytical method for solving this multi-valued\ninverse problem. Such sheets open the door to fabricating machines that can\nperform complex tasks through cyclic transitions between multiple shapes. As a\nproof of concept we design a simple swimmer capable of moving through a fluid\nat low Reynolds numbers."
    },
    {
        "anchor": "A First Principle Approach to Rescale the Dynamics of Simulated\n  Coarse-Grained Macromolecular Liquids: We present a detailed derivation and testing of our approach to rescale the\ndynamics of mesoscale simulations of coarse-grained polymer melts (I. Y.\nLyubimov et al. J. Chem. Phys. \\textbf{132}, 11876, 2010). Starting from the\nfirst-principle Liouville equation and applying the Mori-Zwanzig projection\noperator technique, we derive the Generalized Langevin Equations (GLE) for the\ncoarse-grained representations of the liquid. The chosen slow variables in the\nprojection operators define the length scale of coarse graining. Each polymer\nis represented at two levels of coarse-graining: monomeric as a bead-and-spring\nmodel and molecular as a soft-colloid. In the long-time regime where the\ncenter-of-mass follows Brownian motion and the internal dynamics is completely\nrelaxed, the two descriptions must be equivalent. By enforcing this formal\nrelation we derive from the GLEs the analytical rescaling factors to be applied\nto dynamical data in the coarse-grained representation to recover the monomeric\ndescription. Change in entropy and change in friction are the two corrections\nto be accounted for to compensate the effects of coarse-graining on the polymer\ndynamics. The solution of the memory functions in the coarse-grained\nrepresentations provides the dynamical rescaling of the friction coefficient.\nThe calculation of the internal degrees of freedom provides the correction of\nthe change in entropy due to coarse-graining. The resulting rescaling formalism\nis a function of the coarse-grained model and thermodynamic parameters of the\nsystem simulated. The rescaled dynamics obtained from mesoscale simulations of\npolyethylene, represented as soft colloidal particles, by applying our\nrescaling approach shows a good agreement with data of translational diffusion\nmeasured experimentally and from simulations. The proposed method is used to\npredict self-diffusion coefficients of new polyethylene samples.",
        "positive": "Coarse-grained depletion potentials for anisotropic colloids:\n  application to lock-and-key systems: When a colloid is mixed with a depletant such as a non-adsorbing polymer, one\nobserves attractive effective interactions between the colloidal particles. If\nthese particles are anisotropic, analysis of these effective interactions is\nchallenging in general. We present a method for inference of approximate\n(coarse-grained) effective interaction potentials between such anisotropic\nparticles. Using the example of indented (lock-and-key) colloids, we show how\nnumerical solutions can be used to integrate out the (hard sphere) depletant,\nleading to a depletion potential that accurately characterises the effective\ninteractions. The accuracy of the method is based on matching of contributions\nto the second virial coefficient of the colloids. The simplest version of our\nmethod yields a piecewise-constant effective potential; we also show how this\nscheme can be generalised to other functional forms, where appropriate."
    },
    {
        "anchor": "A simple method to reprogram the binding specificity of DNA-coated\n  colloids that crystallize: DNA-coated colloids can crystallize into a multitude of lattices, ranging\nfrom face-centered cubic to diamond and thereby contribute to our understanding\nof crystallization and open avenues to producing structures with useful\nphotonic properties. Despite the broad potential design space of DNA-coated\ncolloids, the design cycle for synthesizing DNA-coated particles is slow:\npreparing a particle with a new type of DNA sequence takes more than one day\nand requires custom-made and chemically modified DNA that typically takes the\nsupplier over a month to synthesize. Here, we introduce a method to generate\nparticles with custom sequences from a single feed stock in under an hour at\nambient conditions. Our method appends new DNA domains onto the DNA grafted to\ncolloidal particles based on a template that takes the supplier less than a\nweek to produce. The resultant particles crystallize as readily and at the same\ntemperature as those produced via direct chemical synthesis. Moreover, we show\nthat particles coated with a single sequence can be converted into a variety of\nbuilding blocks with differing specificities by appending different DNA\nsequences to them. This approach to DNA-coated particle preparation will make\nit practical to identify optimal and complex particle sequence designs and to\nexpand the use of DNA-coated colloids to a much broader range of investigators\nand commercial entities.",
        "positive": "Effective Langevin equations for a polar tracer in an active bath: We study a polar tracer, having a concave surface, immersed in a\ntwo-dimensional suspension of active particles. Using Brownian dynamics\nsimulations, we measure the distributions and auto-correlation functions of\nforces and torque exerted by active particles on the tracer. The tracer\nexperiences a finite average force along its polar axis, while all the\ncorrelation functions show exponential decay in time. Using these insights we\nconstruct the full coarse-grained Langevin description for tracer position and\norientation, where the active particles are subsumed into an effective\nself-propulsion force and exponentially correlated noise. The ensuing\nmesoscopic dynamics can be described in terms of five dimensionless parameters.\nWe perform a thorough parameter study of the mean squared displacement, which\nillustrates how the different parameters influence the tracer dynamics, which\ncrosses over from a ballistic to diffusive motion. We also demonstrate that the\ndistribution of tracer displacements evolves from a non-Gaussian shape at early\nstages to a Gaussian behavior for sufficiently long times."
    },
    {
        "anchor": "Transport and diffusion of paramagnetic ellipsoidal particles in a\n  rotating magnetic field: Transport and diffusion of paramagnetic ellipsoidal particles under the\naction of a rotating magnetic field are numerically investigated in a\ntwo-dimensional channel. It is found that paramagnetic ellipsoidal particles in\na rotating magnetic field can be rectified in the upper-lower asymmetric\nchannel. The transport and the effective diffusion coefficient are much more\ndifferent and complicated for active particles, while they have similar\nbehaviors and change a little when applying rotating magnetic fields of\ndifferent frequencies for passive particles. For active particles, the\nback-and-forth rotational motion facilitates the effective diffusion\ncoefficient and reduces the rectification, whereas the rotational motion\nsynchronous with the magnetic field suppresses the effective diffusion\ncoefficient and enhances the rectification. There exist optimized values of the\nparameters (the anisotropic degree, the amplitude and frequency of magnetic\nfield, the self-propelled velocity, and the rotational diffusion rate) at which\nthe average velocity and diffusion take their maximal values. Particles with\ndifferent shapes, self-propelled speeds, or rotational diffusion rates will\nmove to the opposite directions and can be separated by applying rotating\nmagnetic fields of suitable strength and frequency. Our results can be used to\nseparate particles, orient the particles along any direction at will during\nmotion, and control the particle diffusion.",
        "positive": "Freezing and phase separation of self-propelled disks: We study numerically a model of non-aligning self-propelled particles\ninteracting through steric repulsion, which was recently shown to exhibit\nactive phase separation in two dimensions in the absence of any attractive\ninteraction or breaking of the orientational symmetry. We construct a phase\ndiagram in terms of activity and packing fraction and identify three distinct\nregimes: a homogeneous liquid with anomalous cluster size distribution, a\nphase-separated state both at high and at low density, and a frozen phase. We\nprovide a physical interpretation of the various regimes and develop scaling\narguments for the boundaries separating them."
    },
    {
        "anchor": "Elastic interactions between colloidal microspheres and elongated convex\n  and concave nanoprisms in nematic liquid crystals: We study mutual alignment and interactions between colloidal particles of\ndissimilar shapes and dimensions when dispersed in a nematic host fluid. Convex\npentagonal and concave starfruit-shaped nanoprisms and microspheres induce\ndipolar or quadrupolar director structures. The ensuing elastic pair\ninteractions between microspheres and nanoprisms are highly dependent on the\nnanoparticle shape being omnidirectionally attractive for convex prisms but\nstrongly anisotropic for concave prisms. Elastic deformations due to spherical\nparticles cause well-defined alignment of complex-shaped nanoparticles at\ndistances much larger than the microsphere size. We characterize distance and\nangular dependencies of elastic pair interaction forces, torques, and binding\nenergies. The studied elasticity-mediated self-assembly of metal and dielectric\nnanoparticles with dissimilar shapes and sizes opens new possibilities for\nself-assembly based fabrication of structured mesoscopic composites with\npredesigned properties.",
        "positive": "Statistical mechanics of dense granular fluids - contacts as\n  quasi-particles: A new first-principles statistical mechanics formulation is proposed to\ndescribe slow and dilated granular fluids, where prolonged intergranular\ncontacts vitiate collision theory. The contacts, where all the important\nphysics takes place, are regarded as quasi-particles that can appear and\ndisappear. A contact potential, $\\nu$, is defined as a measure of the\nfluctuations and the mean coordination number per particle and its fluctuations\nare calculated as a function of it. This formulation extends the Edwards\nstatistical mechanics to slow dynamic systems and converges to it when the\nmotion stops. The theory is applied to a model system of a simply sheared\ngranular material in the limit of small confining stress. The dependence of the\ncontact potential on the shear rate is derived, making it possible to calibrate\n$\\nu$ experimentally and predict the coordination number distribution as a\nfunction of the shear rate. Setting next $\\nu=0$ as the jamming point, where\nthe critical mean coordination number is $z_c$, a finite value is found for the\nshear rate there, $\\dot{\\gamma}_c$. A simple mean field theory then yields the\nscaling of the mean coordination number and its fluctuations near\n$\\dot{\\gamma}_c$. Existing results in the literature appear to support the\npredictions."
    },
    {
        "anchor": "Is there a higher-order Mode Coupling transition in polymer blends?: We present simulations on a binary blend of bead-spring polymer chains. The\nintroduction of monomer size disparity yields very different relaxation times\nfor each component of the blend. Competition between two different arrest\nmechanisms, namely bulk-like dynamics and confinement, leads to an anomalous\nrelaxation scenario for the fast component, characterized by sublinear time\ndependence for mean squared displacements, or logarithmic decay and\nconvex-to-concave crossover for density-density correlators. These anomalous\ndynamic features, which are observed over time intervals extending up to four\ndecades, strongly resemble predictions of Mode Coupling Theory for nearby\nhigher-order transitions. Chain connectivity extends anomalous relaxation over\na wide range of blend compositions.",
        "positive": "Integrated Digital Image Correlation for Micro-Mechanical Parameter\n  Identification in Multiscale Experiments: Micromechanical constitutive parameters are important for many engineering\nmaterials, typically in microelectronic applications and material design. Their\naccurate identification poses a three-fold experimental challenge: (i)\ndeformation of the microstructure is observable only at small scales, requiring\nSEM or other microscopy techniques; (ii) external loadings are applied at a\n(larger) engineering or device scale; and (iii) material parameters typically\ndepend on the applied manufacturing process, necessitating measurements on\nmaterial produced with the same process. In this paper, micromechanical\nparameter identification in heterogeneous solids is addressed through\nmultiscale experiments combined with Integrated Digital Image Correlation\n(IDIC) in conjunction with various possible computational homogenization\nschemes. To this end, some basic concepts underlying multiscale approaches\navailable in the literature are first reviewed, discussing their respective\nadvantages and disadvantages from the computational as well as experimental\npoint of view. A link is made with recently introduced uncoupled methods, which\nallow for identification of material parameter ratios at the microscale, still\nlacking a proper normalization. Two multiscale methods are analysed, allowing\nto bridge the gap between microstructural kinematics and macroscopically\nmeasured forces, providing the required normalization. It is shown that an\nintegrated experimental--computational scheme provides relaxed requirements on\nscale separation. The accuracy and performance of the discussed techniques are\nanalysed by means of virtual experimentation under plane strain and large\nstrain assumptions for unidirectional fibre-reinforced composites. The\nrobustness against image noise is also assessed."
    },
    {
        "anchor": "Near-wall diffusion tensor of an axisymmetric colloidal particle: Hydrodynamic interactions with confining boundaries often lead to drastic\nchanges in the diffusive behaviour of microparticles in suspensions. For\naxially symmetric particles, earlier numerical studies have suggested a simple\nform of the near-wall diffusion matrix which depends on the distance and\norientation of the particle with respect to the wall, which is usually\ncalculated numerically. In this work, we derive explicit analytical formulae\nfor the dominant correction to the bulk diffusion tensor of an axially\nsymmetric colloidal particle due to the presence of a nearby no-slip wall. The\nrelative correction scales as powers of inverse wall-particle distance and its\nangular structure is represented by simple polynomials in sines and cosines of\nthe particle's inclination angle to the wall. We analyse the correction for\ntranslational and rotational motion, as well as the translation-rotation\ncoupling. Our findings provide a simple approximation to the anisotropic\ndiffusion tensor near a wall, which completes and corrects relations known from\nearlier numerical and theoretical findings.",
        "positive": "A link between ECM plasticity and synaptic morphological evolution: We made a link between Extra Cellular Matrix (ECM) plasticity and the\nmorphologi cal changes in synapses after synaptic excitation. A recent study by\nZhang et al \\cite{zhang} showed tha t transmembrane voltage causes movement of\nthe cell membrane. Here we will study the relation between th e mechanical\nproperties of collagen which is the major component of the ECM and synaptic\nmorphological c hanges in relation with the theory of DO Hebb \\cite{hebb}"
    },
    {
        "anchor": "Geometry of flexible filament cohesion: Better contact through twist?: Cohesive interactions between filamentous molecules have broad implications\nfor a range of biological and synthetic materials. While long-standing\ntheoretical approaches have addressed the problem of inter-filament forces from\nthe limit of infinitely rigid rods, the ability of flexible filaments to deform\nintra-filament shape in response to changes in inter-filament geometry has a\nprofound affect on the nature of cohesive interactions. In this paper, we study\ntwo theoretical models of inter-filament cohesion in the opposite limit, in\nwhich filaments are sufficiently flexible to maintain cohesive contact along\ntheir contours, and address, in particular, the role played by\nhelical-interfilament geometry in defining interactions. Specifically, we study\nmodels of featureless, tubular filaments interacting via 1) pair-wise\nLennard-Jones (LJ) interactions between surface elements and 2)\ndepletion-induced filament binding stabilized by electrostatic surface\nrepulsion. Analysis of these models reveals a universal preference for cohesive\nfilament interactions for non-zero helical skew, and further, that in the\nasymptotic limit of vanishing interaction range relative to filament diameter,\nthe skew-dependence of cohesion approaches a geometrically defined limit\ndescribed purely by the close-packing geometry of twisted tubular filaments. We\nfurther analyze non-universal features of the skew-dependence of cohesion at\nsmall-twist for both potentials, and argue that in the LJ model the pair-wise\nsurface attraction generically destabilizes parallel filaments, while in the\nsecond model, pair-wise electrostatic repulsion in combination with\nnon-pairwise additivity of depletion leads to a meta-stable parallel state.",
        "positive": "Gent models for the inflation of spherical balloons: We revisit an iconic deformation of non-linear elasticity: the inflation of a\nrubber spherical thin shell. We use the 3-parameter Mooney and Gent-Gent (GG)\nphenomenological models to explain the stretch-strain curve of a typical\ninflation, as these two models cover a wide spectrum of known models for\nrubber, including the Varga, Mooney-Rivlin, one-term Ogden, Gent-Thomas and\nGent models. We find that the basic physics of inflation exclude the Varga,\none-term Ogden and Gent-Thomas models. We find the link between the exact\nsolution of non-linear elasticity and the membrane and Young-Laplace theories\noften used a priori in the literature. We compare the performance of both\nmodels on fitting the data for experiments on rubber balloons and animal\nbladder. We conclude that the GG model is the most accurate and versatile model\non offer for the modelling of rubber balloon inflation."
    },
    {
        "anchor": "Phase behavior of parallel hard cylinders: We test the performance of a recently proposed fundamental measure density\nfunctional of aligned hard cylinders by calculating the phase diagram of a\nmonodisperse fluid of these particles. We consider all possible liquid\ncrystalline symmetries, namely nematic, smectic and columnar, as well as the\ncrystalline phase. For this purpose we introduce a Gaussian parameterization of\nthe density profile and use it to minimize numerically the functional. We also\ndetermine, from the analytic expression for the structure factor of the uniform\nfluid, the bifurcation points from the nematic to the smectic and columnar\nphases. The equation of state, as obtained from functional minimization, is\ncompared to the available Monte Carlo simulation. The agreement is is very\ngood, nearly perfect in the description of the inhomogeneous phases. The\ncolumnar phase is found to be metastable with respect to the smectic or crystal\nphases, its free energy though being very close to that of the stable phases.\nThis result justifies the observation of a window of stability of the columnar\nphase in some simulations, which disappears as the size of the system\nincreases. The only important deviation between theory and simulations shows up\nin the location of the nematic-smectic transition. This is the common drawback\nof any fundamental measure functional of describing the uniform phase just with\nthe accuracy of scaled particle theory.",
        "positive": "Influence of Solvent Quality on Depletion Potentials in Colloid-Polymer\n  Mixtures: As first explained by the classic Asakura-Oosawa (AO) model, effective\nattractive forces between colloidal particles induced by depletion of\nnonadsorbing polymers can drive demixing of colloid-polymer mixtures into\ncolloid-rich and colloid-poor phases, with practical relevance for purification\nof water, stability of foods and pharmaceuticals, and macromolecular crowding\nin biological cells. By idealizing polymer coils as effective penetrable\nspheres, the AO model qualitatively captures the influence of polymer depletion\non thermodynamic phase behavior of colloidal suspensions. In previous work, we\nextended the AO model to incorporate aspherical polymer conformations and\nshowed that fluctuating shapes of random-walk coils can significantly modify\ndepletion potentials [W. K. Lim and A. R. Denton, Soft Matter 12, 2247 (2016);\nJ. Chem. Phys. 144, 024904 (2016)]. We further demonstrated that the shapes of\npolymers in crowded environments depend sensitively on solvent quality [W. J.\nDavis and A. R. Denton, J. Chem. Phys. 149, 124901 (2018)]. Here we apply Monte\nCarlo simulation to analyze the influence of solvent quality on depletion\npotentials in mixtures of hard sphere colloids and nonadsorbing polymer coils,\nmodeled as ellipsoids whose principal radii fluctuate according to random-walk\nstatistics. We consider both self-avoiding and non-self-avoiding random walks,\ncorresponding to polymers in good and theta solvents, respectively. Our\nsimulation results demonstrate that depletion of polymers of equal molecular\nweight induces much stronger attraction between colloids in good solvents than\nin theta solvents and confirm that depletion interactions are significantly\ninfluenced by aspherical polymer conformations."
    },
    {
        "anchor": "Multiscale modelling of bionano interface: In this work we describe a set of Coarse-grained (CG) tools that allow to\nsimulate the uptake of the nanoparticles (NPs) coated with proteins by a lipid\nbilayer. We describe a CG model to calculate the adsorption energies and the\nmost favorable adsorption orientations of proteins onto a hydrophobic NP. The\nproposed method is then used to calculate the adsorption energies of two common\nproteins in human blood onto neutral and negative charged NPs. We also report\nthe effect of the NP radius on the adsorption energies and validate the\nproposed methodology against full atomistic simulations. We also describe a\nmethodology in which full atomistic simulations of a lipid bilayer and various\nlipid-cholesterol mixtures are used for the extraction of CG pair potentials.\nWe also compare and validate the predictions of simulations at molecular and CG\nlevel. Finally, we present a CG simulation of the interaction a bare NP and of\na NP-protein complex with a lipid bilayer.",
        "positive": "Dielectric response of a ferroelectric nematic liquid crystalline phase\n  in thin cells: We studied dielectric properties of a polar nematic phase (NF) sandwiched\nbetween two gold or ITO electrodes, serving as a cell surfaces. In bulk, NF is\nexpected to exhibit a Goldstone mode (phason), because polarization can\nuniformly rotate with no energy cost. However, because the coupling between the\ndirection of nematic director and polarization is finite, and the confinement,\neven in the absence of the aligning surface layer, induces some energy cost for\na reorientation of polarization, the phason dielectric relaxation frequency is\nmeasured in a kHz regime. The phason mode is easily quenched by a bias electric\nfield, which enables fluctuations in the magnitude of polarization to be\nfollowed in both, the ferronematic and nematic phases. This amplitude (soft)\nmode is also influenced by boundary conditions. A theory describing the phase\nand amplitude fluctuations in the NF phase shows that the free energy of the\nsystem and, consequently, the dielectric response are dominated by\npolarization-related terms with the flexoelectricity being relevant only at a\nvery weak surface anchoring. Contributions due to the nematic elastic terms are\nalways negligible. The model relates the observed low frequency mode to the\ndirector fluctuations weakly coupled to polarization fluctuations."
    },
    {
        "anchor": "Negative energy elasticity in a rubberlike gel: Rubber elasticity is the archetype of the entropic force emerging from the\nsecond law of thermodynamics; numerous experimental and theoretical studies on\nnatural and synthetic rubbers have shown that the elasticity originates mostly\nfrom entropy change with deformation. Similarly, in polymer gels containing a\nlarge amount of solvent, it has also been postulated that the shear modulus\n(the modulus of rigidity) $G$, which is a kind of modulus of elasticity, is\napproximately equivalent to the entropy contribution $G_S$, but this has yet to\nbe verified experimentally. In this study, we measure the temperature\ndependence of the shear modulus $G$ in a rubberlike (hyperelastic) polymer gel\nwhose polymer volume fraction is at most 0.1. As a result, we find that the\nenergy contribution $G_E=G-G_S$ can be a significant negative value, reaching\nup to double the shear modulus $G$ (i.e., $\\left|G_E\\right| \\simeq 2G$),\nalthough the shear modulus of stable materials is generally bound to be\npositive. We further argue that the energy contribution $G_E$ is governed by a\nvanishing temperature that is a universal function of the normalized polymer\nconcentration, and $G_E$ vanishes when the solvent is removed. Our findings\nhighlight the essential difference between rubber elasticity and gel elasticity\n(which were previously thought to be the same) and push the established field\nof gel elasticity into a new direction.",
        "positive": "Apollonian Emulsions: We have discovered the existence of extremely polydisperse High\nInternal-Phase-Ratio Emulsions (HIPE) in which the internal-phase droplets,\npresent at 95% volume fraction, remain spherical and organize themselves in the\navailable space according to Apollonian packing rules. Such Apollonian\nemulsions are obtained from dispersing oil dropwise in water in the presence of\nvery little surfactant, and allowing them to evolve at rest for a week. The\npacking structure of the droplets was confirmed through size distribution\nmeasurements that evolved spontaneously towards power laws with the known\nApollonian exponents, as well as comparison of the structure factors of aged\nHIPEs measured by Small-Angle X-ray Scattering with that of a numerically\nsimulated Random Apollonian Packing. Thanks to the perfect sphericity of the\ndroplets, Apollonian emulsions were found to display Newtonian ow even at such\nextremely high volume fraction. We argue that these fascinating space-filling\nassemblies of spherical droplets are a result of coalescence and fragmentation\nprocesses obeying simple geometrical rules of conserving total volume and\nsphericity, minimizing the elastic energy associated with interactions of\nneighbouring droplets."
    },
    {
        "anchor": "Restructuring a passive colloidal suspension using a rotationally driven\n  particle: The interaction between passive and active/driven particles has introduced a\nnew way to control colloidal suspension properties from particle aggregation to\ncrystallization. Here, we focus on the hydrodynamic interaction between a\nsingle rotational driven particle and a suspension of passive particles near\nthe floor. Using experiments and Stokesian dynamics simulations that account\nfor near-field lubrication, we demonstrate that the flow induced by the driven\nparticle can induce long-ranged rearrangement in a passive suspension. We\nobserve an accumulation of passive particles in front of the driven particle\nand a depletion of passive particles behind the driven particle. This\nrestructuring generates a pattern that can span a range more than $10$ times of\nthe driven particle's radius. We further show that size scale of the pattern is\nonly a function of the particle's height above the floor.",
        "positive": "Radial distribution of RNA genome packaged inside spherical viruses: The problem of RNA genomes packaged inside spherical viruses is studied. The\nviral capsid is modeled as a hollowed sphere. The attraction between RNA\nmolecules and the inner viral capsid is assumed to be non-specific and occurs\nat the inner capsid surface only. For small capsid attraction, it is found that\nmonomer concentration of RNA molecules is maximum at the center of the capsid\nto maximize their configurational entropy. For stronger capsid attraction, RNA\nconcentration peaks at some distance near the capsid. In the latter case, the\ncompetition between the branching of RNA secondary struture and its adsorption\nto the inner capsid results in the formation of a dense layer of RNA near\ncapsid surface. The layer thickness is a slowly varying (logarithmic) function\nof the capsid inner radius. Consequently, for immediate strength of RNA-capsid\ninteraction, the amount of RNA packaged inside a virus is proportional to the\ncapsid {\\em area} (or the number of proteins) instead of its volume. The\nnumerical profiles describe reasonably well the experimentally observed RNA\nnucleotide concentration profiles of various viruses."
    },
    {
        "anchor": "Twist-induced snapping in a bent elastic ribbon: Snapping of a slender structure is utilized in a wide range of natural and\nman-made systems, mostly to achieve rapid movement without relying on\nmuscle-like elements. Although several mechanisms for elastic energy storage\nand rapid release have been studied in detail, a general understanding of the\napproach to design such a kinetic system is a key challenge in mechanics. Here\nwe study a twist-driven buckling and fast flip dynamics of a geometrically\nconstraint ribbon by combining experiments, numerical simulations, and\nanalytical theory. We identify two distinct types of shape transitions; a\nnarrow ribbon snaps, whereas a wide ribbon forms a pair of localized helices.\nWe construct a phase diagram and explain the origin of the boundary, which is\ndetermined only by geometry. We quantify effects of gravity and clarify time\nscale dictating the rapid flipping. Our study reveals the unique role of\ngeometric twist-bend coupling on the fast dynamics of a thin constrained\nstructure, which has implications for a wide range of biophysical and applied\nphysical problems.",
        "positive": "Structure and phase transitions into ionic adsorption layers on liquid\n  interfaces: The structure of ionic adsorption layers is studied via a proper\nthermodynamic treatment of the electrostatic and non-electrostatic interactions\nbetween the surfactant ions as well as of the effect of thermodynamic\nnon-locality. The analysis is also applied to phase transitions into the ionic\nadsorption layer, which interfere further with the oscillatory-diffusive\nstructure of the electric double layer and hydrodynamic stability of squeezing\nwaves in thin liquid films."
    },
    {
        "anchor": "Cytoplasmic Streaming in Plant Cells Emerges Naturally by Microfilament\n  Self-Organization: Many cells exhibit large-scale active circulation of their entire fluid\ncontents, a process termed cytoplasmic streaming. This phenomenon is\nparticularly prevalent in plant cells, often presenting strikingly regimented\nflow patterns. The driving mechanism in such cells is known: myosin-coated\norganelles entrain cytoplasm as they process along actin filament bundles fixed\nat the periphery. Still unknown, however, is the developmental process which\nconstructs the well-ordered actin configurations required for coherent\ncell-scale flow. Previous experimental works on streaming regeneration in cells\nof Characean algae, whose longitudinal flow is perhaps the most regimented of\nall, hint at an autonomous process of microfilament self-organization driving\nthe formation of streaming patterns during morphogenesis. Working from first\nprinciples, we propose a robust model of streaming emergence that combines\nmotor dynamics with both micro- and macroscopic hydrodynamics to explain how\nseveral independent processes, each ineffectual on its own, can reinforce to\nultimately develop the patterns of streaming observed in the Characeae and\nother streaming species.",
        "positive": "Spontaneous formation of permanent shear bands in a mesoscopic model of\n  flowing disordered matter: This study proposes a coherent scenario of the formation of permanent shear\nbands in the flow of yield stress materials. It is a well accepted point of\nview that flow in disordered media is occurring via local plastic events,\ncorresponding to small size rearrangements, that yield a long range stress\nredistribution over the system. Within a minimalistic mesoscopic model that\nincorporates these local dynamics, we study the spatial organisation of the\nlocal plastic events. The most important parameter in this study is the typical\nrestructuring time needed to regain the original structure after a local\nrearrangement. In agreement with a recent mean field study [Coussot \\textit{et\nal., Eur. Phys. J. E}, 2010, \\textbf{33}, 183] we observe a spontaneous\nformation of permanent shear bands, when this restructuring time is large\ncompared to the typical stress release time in a rearrangement. The bands\nconsist of a large number of plastic events within a solid region that remains\nelastic. This heterogeneous flow behaviour is different in nature from the\ntransient dynamical heterogeneities that one observes in the small shear rate\nlimit in flow without shear-banding [Martens \\textit{et al., Phys. Rev. Lett.},\n2011, \\textbf{106}, 156001]. We analyse in detail the dependence of the shear\nbands on system size, shear rate and restructuring time. Further we rationalise\nthe scenario within a mean field version of the spatial model, that produces a\nnon monotonous flow curve for large restructuring times. This explains the\ninstability of the homogeneous flow below a critical shear rate, that\ncorresponds to the minimum of the curve. Our study therefore strongly supports\nthe idea that the characteristic time scales involved in the local dynamics are\nat the physical origin of permanent shear bands."
    },
    {
        "anchor": "Effect of magnetic nanoparticles on the nematic-smectic-A phase\n  transition: Recent experiments on mixed liquid crystals have highlighted the hugely\nsignificant role of ferromagnetic nanoparticle impurities in defining the\nnematic-smectic-A phase transition point. Structured around a Flory-Huggins\nfree energy of isotropic mixing and Landau-de Gennes free energy, this article\npresents a phenomenological mean-field model that quantifies the role of such\nimpurities in analyzing thermodynamic phases, in a mixture of thermotropic\nsmectic liquid crystal and ferromagnetic nanoparticles. First we discuss the\nimpact of ferromagnetic nanoparticles on the isotropic-ferronematic and\nferronematic-ferrosmectic phase transitions and their transition temperatures.\nThis is followed by analysis of various topologies in the phase diagrams. Our\nmodel results indicate that there exists a critical concentration of\nnanoparticle impurities for which the second order N-SmA transition becomes\nfirst order at a tricritical point. Calculations based on this model show\nremarkable agreement with experiment.",
        "positive": "Frequency Dependent Specific Heat from Thermal Effusion in Spherical\n  Geometry: We present a novel method of measuring the frequency dependent specific heat\nat the glass transition applied to 5-polyphenyl-4-ether. The method employs\nthermal waves effusing radially out from the surface of a spherical thermistor\nthat acts as both a heat generator and thermometer. It is a merit of the method\ncompared to planar effusion methods that the influence of the mechanical\nboundary conditions are analytically known. This implies that it is the\nlongitudinal rather than the isobaric specific heat that is measured. As\nanother merit the thermal conductivity and specific heat can be found\nindependently. The method has highest sensitivity at a frequency where the\nthermal diffusion length is comparable to the radius of the heat generator.\nThis limits in practise the frequency range to 2-3 decades. An account of the\n3omega-technique used including higher order terms in the temperature\ndependency of the thermistor and in the power generated is furthermore given."
    },
    {
        "anchor": "Mesoscopic theory for inhomogeneous mixtures: Mesoscopic density functional theory for inhomogeneous mixtures of sperical\nparticles is developed in terms of mesoscopic volume fractions by a systematic\ncoarse-graining procedure starting form microscopic theory. Approximate\nexpressions for the correlation functions and for the grand potential are\nobtained for weak ordering on mesoscopic length scales. Stability analysis of\nthe disordered phase is performed in mean-field approximation (MF) and beyond.\nMF shows existence of either a spinodal or a $\\lambda$-surface on the\nvolume-fractions - temperature phase diagram. Separation into homogeneous\nphases or formation of inhomogeneous distribution of particles occurs on the\nlow-temperature side of the former or the latter surface respectively,\ndepending on both the interaction potentials and the size ratios between\nparticles of different species. Beyond MF the spinodal surface is shifted, and\nthe instability at the $\\lambda$-surface is suppressed by fluctuations. We\ninterpret the $\\lambda$-surface as a borderline between homogeneous and\ninhomogeneous (containing clusters or other aggregates) structure of the\ndisordered phase. For two-component systems explicit expressions for the MF\nspinodal and $\\lambda$-surfaces are derived. Examples of interaction potentials\nof simple form are analyzed in some detail, in order to identify conditions\nleading to inhomogeneous structures.",
        "positive": "Molecular Packing Analysis of the Smectic E Phase of a\n  Benzothieno-benzothiophene Derivative by a Combined Experimental /\n  Computational Approach: The molecule 2-decyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene has\ngained a lot of attention, since high charge carrier mobility was observed in\nthin film transistors. Its thermotropic liquid crystalline states may play an\nimportant role in the thin film formation, since the smectic A and the smectic\nE phase (SmE) are claimed to be pre-stages of the final bulk structure. To\nunderstand the phase diversity, structural characterisation of solution\nprocessed thin films are performed by X-ray diffraction in the complete\ntemperature range up to the isotropic state at 240{\\deg}C. The diffraction\npattern of the SmE phase is analysed in detail. Peak broadening analysis\nreveals that the crystallographic order across the smectic layers is larger\nthan the order along the smectic layers. A combined experimental and\ncomputational approach is used to determine the molecular packing within the\nSmE phase. It leads to a number of different packing motifs. A comparison of\nthe calculated diffraction pattern with the experimental results reveals that\nnano-segregation is present within the SmE phase. Energy consideration clearly\nfavours a herringbone arrangement of the aromatic units. The nano-segregation\nwithin the SmE phase with herringbone packing of the aromatic units is\naccompanied with interdigidation of sidechains from neighbouring smectic\nlayers."
    },
    {
        "anchor": "Normal stress anisotropy and marginal stability in athermal elastic\n  networks: Hydrogels of semiflexible biopolymers such as collagen have been shown to\ncontract axially under shear strain, in contrast to the axial dilation observed\nfor most elastic materials. Recent work has shown that this behavior can be\nunderstood in terms of the porous, two-component nature and consequent\ntime-dependent compressibility of hydrogels. The apparent normal stress\nmeasured by a torsional rheometer reflects only the tensile contribution of the\naxial component $\\sigma_{zz}$ on long (compressible) timescales, crossing over\nto the first normal stress difference, $N_1 = \\sigma_{xx}-\\sigma_{zz}$ at short\n(incompressible) times. While the behavior of $N_1$ is well understood for\nisotropic viscoelastic materials undergoing affine shear deformation,\nbiopolymer networks are often anisotropic and deform nonaffinely. Here, we\nnumerically study the normal stresses that arise under shear in subisostatic,\nathermal semiflexible polymer networks. We show that such systems exhibit\nstrong deviations from affine behavior and that these anomalies are controlled\nby a rigidity transition as a function of strain.",
        "positive": "Rheotaxis of spherical active particles near a planar wall: For active particles the interplay between the self-generated hydrodynamic\nflow and an external shear flow, especially near bounding surfaces, can result\nin a rich behavior of the particles not easily foreseen from the consideration\nof the active and external driving mechanisms in isolation. For instance, under\ncertain conditions, the particles exhibit \"rheotaxis,\" i.e., they align their\ndirection of motion with the plane of shear spanned by the direction of the\nflow and the normal of the bounding surface and move with or against the flow.\nTo date, studies of rheotaxis have focused on elongated particles (e.g.,\nspermatozoa), for which rheotaxis can be understood intuitively in terms of a\n\"weather vane\" mechanism. Here we investigate the possibility that spherical\nactive particles, for which the \"weather vane\" mechanism is excluded due to the\nsymmetry of the shape, may nevertheless exhibit rheotaxis. Combining analytical\nand numerical calculations, we show that, for a broad class of spherical active\nparticles, rheotactic behavior may emerge via a mechanism which involves\n\"self-trapping\" near a hard wall owing to the active propulsion of the\nparticles, combined with their rotation, alignment, and \"locking\" of the\ndirection of motion into the shear plane. In this state, the particles move\nsolely up- or downstream at a steady height and orientation."
    },
    {
        "anchor": "Excimer formation of pyrene labeled lipids interpreted by means of\n  coarse-grained molecular dynamics simulations: The excimer formation dynamics of pyrene-labeled molecules in lipid bilayers\ndepends on molecular motion over distances of the order of 1-2 nm. From the\nconcentration dependence of the excimer photoemission curve, it is possible to\nderive a value for the lipid self-diffusion coefficient. This technique has\nbeen intensively used in the past twenty years, leading to rather large\nnumerical values for self-diffusion compared with other approaches based on\nfluorescent probes tracking. In most cases, the interpretation of the\nexperimental data rely on models for diffusion limited 2d reaction rates, or\ncomparison with 2d lattice random walks. Our approach uses realistic molecular\ndynamics trajectories to reinterpret these experiments. Based on a well\nestablished coarse-grained model for lipid MD simulations (Martini), we show\nhow to relate simulation results to experimental data on excimer formation. Our\nprocedure is quite general and is applicable to all diffusion-limited kinetic\nprocesses. Key to our approach is the determination of the acceleration factor\nof lipid coarse-grained numerical models compared to reality. We find a\nsignificant reduction of the diffusion coefficient values, in particular when\ninterleaflet association is taken into account. Our work does not point to\ndeviation from a diffusion-limited mechanism but indicates that the excimer\nformation across bilayer leaflets could be hindered.",
        "positive": "Adversarial Reverse Mapping of Equilibrated Condensed-Phase Molecular\n  Structures: A tight and consistent link between resolutions is crucial to further expand\nthe impact of multiscale modeling for complex materials. We herein tackle the\ngeneration of condensed molecular structures as a refinement -- backmapping --\nof a coarse-grained structure. Traditional schemes start from a rough\ncoarse-to-fine mapping and perform further energy minimization and molecular\ndynamics simulations to equilibrate the system. In this study we introduce\nDeepBackmap: A deep neural network based approach to directly predict\nequilibrated molecular structures for condensed-phase systems. We use\ngenerative adversarial networks to learn the Boltzmann distribution from\ntraining data and realize reverse mapping by using the coarse-grained structure\nas a conditional input. We apply our method to a challenging condensed-phase\npolymeric system. We observe that the model trained in a melt has remarkable\ntransferability to the crystalline phase. The combination of data-driven and\nphysics-based aspects of our architecture help reach temperature\ntransferability with only limited training data."
    },
    {
        "anchor": "Length scales in Brownian yet non-Gaussian dynamics: According to the classical theory of Brownian motion, the mean squared\ndisplacement of diffusing particles evolves linearly with time whereas the\ndistribution of their displacements is Gaussian. However, recent experiments on\nmesoscopic particle systems have discovered Brownian yet non-Gaussian regimes\nwhere diffusion coexists with an exponential tail in the distribution of\ndisplacements. Here we show that, contrary to the present theoretical\nunderstanding, the length scale $\\lambda$ associated to this exponential\ndistribution does not necessarily scale in a diffusive way. Simulations of\nLennard- Jones systems reveal a behavior $\\lambda \\sim t^{1/3}$ in three\ndimensions and $\\lambda \\sim t^{1/2}$ in two dimensions. We propose a scaling\ntheory based on the idea of hopping motion to explain this result. In contrast,\nsimulations of a tetrahedral gelling system, where particles interact by a\nnon-isotropic potential, yield a temperature-dependent scaling of $\\lambda$. We\ninterpret this behavior in terms of an intermittent hopping motion. Our\nfindings link the Brownian yet non-Gaussian phenomenon with generic features of\nglassy dynamics and open new experimental perspectives on the class of\nmolecular and supramolecular systems whose dynamics is ruled by rare events.",
        "positive": "The path to fracture in granular flows: dynamics of contact networks: Capturing the dynamics of granular flows at intermediate length scales can\noften be difficult. We propose studying the dynamics of contact networks as a\nnew tool to study fracture at intermediate scales. Using experimental\nthree-dimensional flow fields with particle-scale resolution, we calculate the\ntime evolving broken-links network and find that a giant component of this\nnetwork is formed as shear is applied to this system. We implement a model of\nlink breakages where the probability of a link breaking is proportional to the\naverage rate of longitudinal strain (elongation) in the direction of the edge\nand find that the model demonstrates qualitative agreement with the data when\nstudying the onset of the giant component. We note, however, that the\nbroken-links network formed in the model is less clustered than our\nexperimental observations, indicating that the model reflects less localized\nbreakage events and does not fully capture the dynamics of the granular flow."
    },
    {
        "anchor": "Axisymmetric Ridges and Circumferential Buckling of Indented Shells of\n  Revolution: When poking a thin shell-like structure, like a plastic water bottle,\nexperience shows that an initial axisymmetric dimple forms around the\nindentation point. The ridge of this dimple, with increasing indentation,\neventually buckles into a polygonal shape. The polygon order generally\ncontinues to increase with further indentation. In the case of spherical\nshells, both the underlying axisymmetric deformation and the buckling evolution\nhave been studied in detail. However, little is known about the behaviour of\ngeneral geometries. In this work we describe the geometrical and mechanical\nfeatures of the axisymmetric ridge that forms in indented general shells of\nrevolution with non-negative Gaussian curvature and the conditions for\ncircumferential buckling of this ridge. We show that, under the assumption of\n`mirror buckling' a single unified description of this ridge can be written if\nthe problem is non-dimensionalised using the local slope of the undeformed\nshell mid-profile at the ridge radial location. In dimensional form the ridge\nproperties evolve in quite different ways for different mid-profiles. Focusing\non the indentation of shallow shells of revolution with constant Gaussian\ncurvature, we use our theoretical framework to study the properties of the\nridge at the circumferential buckling threshold and evaluate the validity of\nthe mirror buckling assumption against a linear stability analysis on the\nshallow shell equations, showing very good agreement. Our results highlight\nthat circumferential buckling in indented thin shells is controlled by a\ncomplex interplay between the geometry and the stress state in the ridge. The\nresults of our study will provide greater insight into the mechanics of thin\nshells. This could enable indentation to be used to measure the mechanical\nproperties of a wide range of shell geometries or used to design shells with\nspecific mechanical behaviours.",
        "positive": "Crystallography on Curved Surfaces: We study static and dynamical properties that distinguish two dimensional\ncrystals constrained to lie on a curved substrate from their flat space\ncounterparts. A generic mechanism of dislocation unbinding in the presence of\nvarying Gaussian curvature is presented in the context of a model surface\namenable to full analytical treatment. We find that glide diffusion of isolated\ndislocations is suppressed by a binding potential of purely geometrical origin.\nFinally, the energetics and biased diffusion dynamics of point defects such as\nvacancies and interstitials is explained in terms of their geometric potential."
    },
    {
        "anchor": "General theory of asymmetric steric interactions in electrostatic double\n  layers: We study the Poisson-Boltzmann equation in the context of dense charged\nfluids where steric effects become important. We generalise the lattice gas\ntheory by introducing a Flory-Huggins entropy for ions of differing volumes and\nthen compare the effective free energy density to other approximations, valid\nfor more realistic equations of state, such as the Carnahan-Starling\napproximation and find strong differences in the shapes of the free energy\nfunctions. We solve the Carnahan-Starling model in the high density limit, and\ndemonstrate a slow, power-law convergence at high potentials. We elucidate how\nequivalent convex free energy functions can be constructed that describe steric\neffects in a manner which is more convenient for numerical minimisation.",
        "positive": "Line tension and morphology of a droplet and a bubble attached to the\n  inner wall of a spherical cavity: The effects of line tension on the morphology of a lens-shaped droplet and\nbubble placed on the inner wall of a spherical cavity are studied. The contact\nangle between the lens-shaped droplet and the concave spherical substrate is\nexpressed by the generalized Young's formula. The equator of the spherical\nsubstrate is found to play a crucial role. Neither a droplet with its contact\nline on the upper hemisphere of the substrate nor one with its contact line on\nthe lower hemisphere can transform into each other continuously. On a\nhydrophobic substrate, the contact angle jumps discontinuously to\n$180^{\\circ}$, and the droplet is detached from the substrate to form a\nspherical droplet when the line tension is positive and large. This is similar\nto the drying transition on a flat substrate. On the other hand, on a\nhydrophilic substrate, the contact angle jumps discontinuously to $0^{\\circ}$\nwhen the line tension is positive and large. Then, the droplet spread over the\nwhole inner wall to leave a spherical bubble. Therefore, not only the drying\ntransition but also the wetting transition is induced by positive line tension\non a concave spherical substrate. There also exist stable as well as metastable\ndroplets, whose phase diagrams can be complex. When the line tension is\nnegative and its magnitude increases, the contact line approaches the equator\ninfinitesimally from either above or below. However, it cannot cross the\nequator of a spherical cavity continuously. The droplet with a contact line\nthat coincides with the equator is a singular droplet. The contact line is\npinned and cannot move, irrespective of the magnitude of the line tension."
    },
    {
        "anchor": "Numerical study of the microscopic structure of jammed systems: from\n  inferring their dynamics to finite size scaling: In this thesis I present most of the results obtained during my PhD, where I\nworked on different subjects regarding jamming in systems of frictionless\nspheres. In particular, I focused on microscopic properties of jammed packings,\nsuch as the distribution of contact forces and interparticle gaps, as well as\nthe single particle dynamics that occur near the jamming point. Several of\nthese results have already been presented in Refs. [1,2], but here I include a\nmore detailed analysis of some of them. Besides, all the results of the second\nchapter are new, even if related to such works.",
        "positive": "Quantized Self-Assembly of Discotic Rings in a Liquid Crystal Confined\n  in Nanopores: Disklike molecules with aromatic cores spontaneously stack up in linear\ncolumns with high, one-dimensional charge carrier mobilities along the columnar\naxes making them prominent model systems for functional, self-organized matter.\nWe show by high-resolution optical birefringence and synchrotron-based X-ray\ndiffraction that confining a thermotropic discotic liquid crystal in\ncylindrical nanopores induces a quantized formation of annular layers\nconsisting of concentric circular bent columns, unknown in the bulk state.\nStarting from the walls this ring self-assembly propagates layer by layer\ntowards the pore center in the supercooled domain of the bulk\nisotropic-columnar transition and thus allows one to switch on and off\nreversibly single, nanosized rings through small temperature variations. By\nestablishing a Gibbs free energy phase diagram we trace the phase transition\nquantization to the discreteness of the layers' excess bend deformation\nenergies in comparison to the thermal energy, even for this near\nroom-temperature system. Monte Carlo simulations yielding spatially resolved\nnematic order parameters, density maps and bond-forientational order parameters\ncorroborate the universality and robustness of the confinement-induced columnar\nring formation as well as its quantized nature."
    },
    {
        "anchor": "Spontaneous Patterning of Confined Granular Rods: Vertically vibrated rod-shaped granular materials confined to quasi-2D\ncontainers self organize into distinct patterns. We find, consistent with\ntheory and simulation, a density dependent isotropic-nematic transition. Along\nthe walls, rods interact sterically to form a wetting layer. For high rod\ndensities, complex patterns emerge as a result of competition between bulk and\nboundary alignment. A continuum elastic energy accounting for nematic\ndistortion and local wall anchoring reproduces the structures seen\nexperimentally.",
        "positive": "Diffusion in a Granular Fluid - Theory: Many important properties of granular fluids can be represented by a system\nof hard spheres with inelastic collisions. Traditional methods of\nnonequilibrium statistical mechanics are effective for analysis and description\nof the inelastic case as well. This is illustrated here for diffusion of an\nimpurity particle in a fluid undergoing homogeneous cooling. An appropriate\nscaling of the Liouville equation is described such that the homogeneous\ncooling ensemble and associated time correlation functions map to those of a\nstationary state. In this form the familiar methods of linear response can be\napplied, leading to Green - Kubo and Einstein representations of diffusion in\nterms of the velocity and mean square displacement correlation functions. These\ncorrelation functions are evaluated approximately using a cumulant expansion\nand from kinetic theory, providing the diffusion coefficient as a function of\nthe density and the restitution coefficients. Comparisons with results from\nmolecular dynamics simulation are given in the following companion paper."
    },
    {
        "anchor": "The role of shape disorder in the collective behaviour of aligned\n  fibrous matter: We study the compression of bundles of aligned macroscopic fibers with\nintrinsic shape disorder, as found in human hair and in many other natural and\nman-made systems. We show by a combination of experiments, numerical\nsimulations and theory how the statistical properties of the shapes of the\nfibers control the collective mechanical behaviour of the bundles. This work\npaves the way for designing aligned fibrous matter with pre-required properties\nfrom large numbers of individual strands of selected geometry and rigidity.",
        "positive": "Core-Shell Microgel-Based Surface Coatings with Linear Thermoresponse: We study the swelling and shrinking behavior of core-shell microgels adsorbed\non silicon wafers. In these systems, the core is made of cross-linked poly(N\nisopropylmethacrylamide) and the shell consists of cross linked poly(N-n\npropylacrylamide). In suspension, these particles exhibit an extended linear\nswelling behavior in the temperature interval between the lower critical\nsolution temperatures of the two polymers. Using ellipsometry and AFM, we show\nthat this linear response is also observed in the adsorbed state."
    },
    {
        "anchor": "Ellipsoidal particles at fluid interfaces: For partially wetting, ellipsoidal colloids trapped at a fluid interface,\ntheir effective, interface--mediated interactions of capillary and\nfluctuation--induced type are analyzed. For contact angles different from\n90$^o$, static interface deformations arise which lead to anisotropic capillary\nforces that are substantial already for micrometer--sized particles. The\ncapillary problem is solved using an efficient perturbative treatment which\nallows a fast determination of the capillary interaction for all distances\nbetween and orientations of two particles. Besides static capillary forces,\nfluctuation--induced forces caused by thermally excited capillary waves arise\nat fluid interfaces. For the specific choice of a spatially fixed three--phase\ncontact line, the asymptotic behavior of the fluctuation--induced force is\ndetermined analytically for both the close--distance and the long--distance\nregime and compared to numerical solutions.",
        "positive": "Origin of the slow dynamics and the aging of a soft glass: We study by light microscopy a soft glass consisting of a compact arrangement\nof polydisperse elastic spheres. We show that its slow and non-stationary\ndynamics results from the unavoidable small fluctuations of temperature, which\ninduce intermittent local mechanical shear in the sample, because of thermal\nexpansion and contraction. Temperature-induced shear provokes both reversible\nand irreversible rearrangements whose amplitude decreases with time, leading to\nan exponential slowing down of the dynamics with sample age."
    },
    {
        "anchor": "X-Ray Scattering near a Liquid - Vapor Phase Transition at the n-Hexane\n  - Water Interface: The molecular structure of neutral n-triacontanol mesophases at the n-hexane\n- water interface has been studied by diffuse X-ray scattering using\nsynchrotron radiation. According to the experimental data, a transition to the\nmultilayer adsorption of alkanol occurs at a temperature below the transition\nfrom a gas phase to a liquid Gibbs monolayer.",
        "positive": "Freezing-induced ordering of block copolymer micelles: We demonstrate here the ordering of block copolymer micelles by ice\ntemplating, below 0 {\\deg}C. We used this for the preparation of silica\nmonoliths that present an ice-templated macroporosity, combined with a 2D\nhexagonal mesostructure templated by the addition of P123. We propose a\nmechanism triggered by the progressive freezing-induced concentration."
    },
    {
        "anchor": "Universality in the dynamics of vesicle translocation through a hole: We analyze the translocation process of a spherical vesicle, made of membrane\nand incompressible fluid, through a hole smaller than the vesicle size, driven\nby pressure difference $\\Delta P$. We show that such a vesicle shows certain\nuniversal characteristics which is independent of the details of the membrane\nelasticity; (i) there is a critical pressure $\\Delta P_{\\rm c}$ below which no\ntranslocation occurs, (ii) $\\Delta P_{\\rm c}$ decreases to zero as the vesicle\nradius $R_0$ approaches the hole radius $a$, satisfying the scaling relation\n$\\Delta P_{\\rm c} \\sim (R_0 - a)^{3/2}$, and (iii) the translocation time\n$\\tau$ diverges as $\\Delta P$ decreases to $\\Delta P_{\\rm c}$, satisfying the\nscaling relation $\\tau \\sim (\\Delta P -\\Delta P_{\\rm c})^{-1/2}$.",
        "positive": "Shocks in Vertically Oscillated Granular Layers: We study shock formation in vertically oscillated granular layers, using both\nmolecular dynamics simulations and numerical solutions of continuum equations\nto Navier-Stokes order. A flat layer of grains is thrown up from an oscillating\nplate during each oscillation cycle and collides with the plate later in the\ncycle. The collisions produce layer compaction near the plate and a high\ntemperature shock front that rapidly propagates upward through the layer. The\nshock is highly time-dependent, propagating through the layer in only a quarter\nof the cycle. We compare numerical solutions of the continuum equations to\nmolecular dynamics simulations that assume binary, instantaneous collisions\nbetween frictionless hard spheres. The two simulations yield results for the\nshock position, shape, and speed that agree well. An investigation of the\neffect of inelasticity shows that the shock velocity increases continuously\nwith decreasing inelasticity; the elastic limit is not singular."
    },
    {
        "anchor": "Density Scaling of the Dynamics of Vitrifying Liquids and its\n  Relationship to the Dynamic Crossover: A central question concerning glass-formation has been what governs the\nkinetic arrest of the quenched liquid - cooling reduces the thermal energy\nwhich molecules need to surmount local potential barriers, while the\naccompanying volume contraction promotes molecular crowding and congestion (and\nthus altering the potential). Recent experimental findings have shown that both\nthermal energy and density contribute significantly to the\ntemperature-dependence of vitrifying liquids. Herein, we show that the scaling\n(superpositioning) of the relaxation times near the glassy state, by expressing\nthem as a function of temperature and the specific volume, leads to a\nmodification of the usual fragility curves, whereby differences in the extent\nof departure from Arrhenius behavior can be rationalized. More intriguingly,\nthe characteristic changes in the relaxation properties (i.e., the 'dynamic\ncrossover'), occurring well above the liquid-to-glass transition, are shown to\nbe related to the same function that superposes the relaxation data.",
        "positive": "Do thermal diffusion and Dufour coefficients satisfy Onsager's\n  reciprocity relation?: It is commonly admitted that in liquids the thermal diffusion and Dufour\ncoefficients $D_{T}$\\ and $D_{F}$ satisfy Onsager's reciprocity. From their\nrelation to the cross-coefficients of the phenomenological equations, we are\nled to the conclusion that this is not the case in general. As illustrative and\nphysically relevant examples, we discuss micellar solutions and colloidal\nsuspensions, where $D_{T}$ arises from chemical reactions or viscous effects\nbut is not related to the Dufour coefficient $D_{F}$. The situation is less\nclear for binary molecular mixtures; available experimental and simulation data\ndo not settle the question whether $D_{T}$\\ and $D_{F}$ are reciprocal\ncoefficients."
    },
    {
        "anchor": "Why monovalent salt reduces charge inversion of macroion by trivalent\n  counterions: A macroion with a strongly charged negative surface in 3:1 salt water\nsolution becomes net positive due to adsorption of an excessive number of\npositive 3-ions. The widely accepted theory of such charge inversion is based\non the idea that adsorbed at the macroion surface 3-ions form a two-dimensional\nstrongly correlated liquid which attracts excessive 3-ions by their negative\nimages (correlation holes). In the absence of 1:1 salt this theory reasonably\nagrees with experiments and numerical simulations. However, the same theory\npredicts that adding a large concentration of 1:1 salt increases the net\npositive charge, while experiments and simulations show that the charge\ndecreases. In this paper we argue that the theory was aiming at the case of a\nvery large macroion surface charge and ignored the effect of the competing\nattraction of 3-ion to its screening atmosphere in the bulk of the solution. We\nshow that for parameters of experiments and simulations this effect makes\ncharge inversion weak and extremely sensitive to screening by large\nconcentration of 1:1 salt. As a result charge inversion decreases with addition\nof 1:1 salt in agreement with experiments and simulations.",
        "positive": "Long-term memory and synapse-like dynamics in two-dimensional\n  nanofluidic channels: Fine-tuned ion transport across nanoscale pores is key to many biological\nprocesses such as neurotransmission. Recent advances have enabled the\nconfinement of water and ions to two dimensions, unveiling transport properties\nunreachable at larger scales and triggering hopes to reproduce the ionic\nmachinery of biological systems. Here we report experiments demonstrating the\nemergence of memory in the transport of aqueous electrolytes across\n(sub)nanoscale channels. We unveiled two types of nanofluidic memristors,\ndepending on channel material and confinement, with memory from minutes to\nhours. We explained how large timescales could emerge from interfacial\nprocesses like ionic self-assembly or surface adsorption. Such behavior allowed\nus to implement Hebbian learning with nanofluidic systems. This result lays the\nground for biomimetic computations on aqueous electrolytic chips."
    },
    {
        "anchor": "Competing exchange and irreversible reactions in a linear\n  co-polycondensation lead to a broad composition window where tunable high\n  molecular weight polymers can be prepared: A co-polycondensation reaction is discussed analytically and by Monte-Carlo\nsimulations where two reactive units compete for reactions with an alternating\nthird reactive unit, whereby irreversible reactions replace bonds which are\nable to undergo exchange reactions. The resulting number average molar mass,\n$M_{\\text{n}}$, exhibits only one distinct peak at the stoichiometric condition\nof both competitors with the alternating partner. The weight average molar\nmass, $M_{\\text{w}}$, reaches an additional second peak at the stoichiometric\ncondition between the dominating competitor and the alternating partner. Both\npeaks of $M_{\\text{w}}$ surround a range of compositions where a rather high\nand approximately constant $M_{\\text{w}}$ is obtained. The degree of\npolymerization of the dominating and alternating reaction partners is rather\ninsensitive towards composition fluctuations if the reaction mixture remains\nwithin this composition window. This promotes high molecular weight species and\nmore homogeneous weight distributions at incomplete mixing conditions. An ideal\nreference case (identical reaction rates for all reactions) is solved\nanalytically to describe these reactions. The position of the stable\ncomposition window and the average molar masses inside this window can be tuned\nby choosing appropriate precursor molecules, reaction mixtures or post-tuning\nsteps at later times.",
        "positive": "Dynamic heterogeneity in an orientational glass: Family of compounds CBr$_n$Cl$_{4-n}$ has been proven helpful in unraveling\nmicroscopic mechanisms responsible of glassy behavior. Some of the family\nmembers show translational ordered phases with minimal disorder which appears\nto reveal glassy features, thus deserving special attention in the search for\nuniversal glass anomalies. In this work, we studied CBrCl$_3$ dynamics by\nperforming extensive molecular dynamics simulations. Molecules of this compound\nperform reorientational discrete jumps, where the atoms exchange equivalent\npositions among each other revealing a cage-orientational jump motion fully\ncomparable to the cage-rototranslational jump motion in supercooled liquids.\nCorrelation times were calculated from rotational autocorrelation functions\nshowing good agreement with previous reported dielectric results. From mean\nwaiting and persistence times calculated directly from trajectory results, we\nare able to explain which microscopic mechanisms lead to characteristic times\nassociated with $\\alpha$ and $\\beta$-relaxation times measured experimentally.\nWe found that two nonequivalent groups of molecules have a longer\ncharacteristic time than the other two nonequivalent groups, both of them\nbelonging to the asymmetric unit of the monoclinic (C2/c) lattice."
    },
    {
        "anchor": "Pendulums, Drops and Rods: a physical analogy: A liquid meniscus, a bending rod (also called elastica) and a simple pendulum\nare all described by the same non-dimensional equation. The oscillatory regime\nof the pendulum corresponds to buckling rods and pendant drops, and the\nhigh-velocity regime corresponds to spherical drops, puddles and multiple rod\nloopings. We study this analogy in a didactic way and discuss how, despite this\ncommon governing equation, the three systems are not completely equivalent. We\nalso consider the cylindrical deformations of an inextensible, flexible\nmembrane containing a liquid, which in some sense interpolates between the\nmeniscus and rod conformations.",
        "positive": "Structure and interaction potentials in solid-supported lipid membranes\n  studied by X-ray reflectivity at varied osmotic pressure: Highly oriented solid-supported lipid membranes in stacks of controlled\nnumber $N \\simeq 16$ (oligo-membranes) have been prepared by spin-coating using\nthe uncharged lipid model system 1,2-dimyristoyl-sn-glycero-3-phosphocholine\n(DMPC). The samples have been immersed in aqueous polymer solutions for control\nof osmotic pressure and have been studied by X-ray reflectivity. The bilayer\nstructure and fluctuations have been determined by modelling the data over the\nfull q-range. Thermal fluctuations are described using the continuous smectic\nHamiltonian with the appropriate boundary conditions at the substrate and at\nthe free surface of the stack. The resulting fluctuation amplitudes and the\npressure-distance relation are discussed in view of the inter-bilayer\npotential."
    },
    {
        "anchor": "Deterministic Interrelation Between Elastic Moduli in Critically Elastic\n  Materials: Critically elastic materials - those that are rigid with a single state of\nself-stress - can be generated from parent systems with two states of\nself-stress by the removal of one of many constraints. We show that the elastic\nmoduli of the resulting homogeneous and isotropic daughter systems are\ninterrelated by a universal functional form parametrized by properties of the\nparent. In simulations of both spring networks and packings of soft spheres,\njudicious choice of parent systems and bond removal allows for the selection of\na wide variety of moduli and Poisson's ratios in the critically elastic\nsystems, providing a framework for versatile deterministic selection of\nmechanical properties.",
        "positive": "Lattice nano-ripples revealed in peptide microcrystals by scanning\n  electron nanodiffraction: Changes in lattice structure across sub-regions of protein crystals are\nchallenging to assess when relying on whole crystal measurements. Because of\nthis difficulty, macromolecular structure determination from protein micro and\nnano crystals requires assumptions of bulk crystallinity and domain block\nsubstructure. To evaluate the fidelity of these assumptions in protein\nnanocrystals we map lattice structure across micron size areas of cryogenically\npreserved three-dimensional peptide crystals using a nano-focused electron\nbeam. This approach produces diffraction from as few as 1,500 molecules in a\ncrystal, is sensitive to crystal thickness and three-dimensional lattice\norientation. Real-space maps reconstructed from unsupervised classification of\ndiffraction patterns across a crystal reveal regions of crystal order/disorder\nand three-dimensional lattice reorientation on a 20nm scale. The lattice\nnano-ripples observed in micron-sized macromolecular crystals provide a direct\nview of their plasticity. Knowledge of these features is a first step to\nunderstanding crystalline macromolecular self-assembly and improving the\ndetermination of structures from protein nano and microcrystals from single or\nserial crystal diffraction."
    },
    {
        "anchor": "An experimental assessment of displacement fluctuations in a 2D granular\n  material subjected to shear: In a granular material, a macroscopically homogeneous deformation does not\ncorrespond to a homogeneous displacement field when looking at the individual\ngrains. The deviation of a grain displacement from the value dictated by the\ncontinuum field (referred to as fluctuation) is likely to hold valuable\ninformation about the characteristic length(s) involved in grains'\nrearrangement, which is the principal mechanism of irreversible deformation for\ngranular materials. This paper shows a selection of results from a series of\nshear tests on a 2D analogue granular material. We have followed the route\nopened by the pioneering work of Radja\\\"i and Roux (2002), and used the same\nframework to analyze our experimental data on displacement fluctuations.\nDigital Image Correlation has been used to measure and characterize the\ndisplacement fluctuations. The analysis of their spatial organization reveals\nthe emergence of a minimum length scale that is in the order of 10 times the\nmean particle size.",
        "positive": "Translational and rotational dynamics of a self-propelled Janus probe in\n  crowded environments: We computationally investigate the dynamics of a self-propelled Janus probe\nin crowded environments. The crowding is caused by the presence of viscoelastic\npolymers or non-viscoelastic disconnected monomers. Our simulations show that\nthe translational, as well as rotational mean square displacements, have a\ndistinctive three-step growth for fixed values of self-propulsion force, and\nsteadily increase with self-propulsion, irrespective of the nature of the\ncrowder. On the other hand, in the absence of crowders, the rotational dynamics\nof the Janus probe is independent of self-propulsion force. On replacing the\nrepulsive polymers with sticky ones, translational and rotational mean square\ndisplacements of the Janus probe show a sharp drop. Since different faces of a\nJanus particle interact differently with the environment, we show that the\ndirection of self-propulsion also affects its dynamics. The ratio of long-time\ntranslational and rotational diffusivities of the self-propelled probe with a\nfixed self-propulsion, when plotted against the area fraction of the crowders,\npasses through a minima and at higher area fraction merges to its value in the\nabsence of the crowder. This points towards the decoupling of translational and\nrotational dynamics of the self-propelled probe at intermediate area fraction\nof the crowders. However, such translational-rotational decoupling is absent\nfor passive probes."
    },
    {
        "anchor": "Alternative Approach to the Excluded Volume Problem The Critical\n  Behavior of the Exponent $\u03bd$: We present the alternative derivation of the excluded volume equation. The\nresulting equation is mathematically identical to the one proposed in the\npreceding paper. As a result, the theory reproduces well the observed points by\nSANS (small angle neutron scattering) experiments. The equation is applied to\nthe coil-globule transition of branched molecules. It is found that in the\nentire region of poor solvent regimes ($T<\\Theta$), the exponent\n$\\kappa=d\\log\\alpha\\,/\\,d\\log N\\, (N\\rightarrow\\infty)$ takes the value\n$\\frac{1}{12}$, showing that contrary to the case of linear molecules\n($\\kappa=-\\frac{1}{6}$), the expansion factor increases indefinitely as $N$\nincreases. The theory is then applied to concentrated systems in good solvents.\nIt is found that for the entire region of $0<\\bar{\\phi}\\le 1$, the gradients\n$\\kappa$ seem to converge on a common value lying somewhere from\n$\\kappa=\\frac{1}{12}$ to $0.1$. Since $\\nu_{dilute}=\\tfrac{1}{2}$,\n$\\nu_{melt}=\\tfrac{1}{3}$, and $0.33\\cdots\\le\\nu_{conc}\\,(=\\nu_{0}+\\kappa)\n<0.35$ for $0<\\bar{\\phi}\\le 1$, the simulation results suggest that the\nexponents $\\kappa$ and $\\nu$ change abruptly from phases to phases; there are\nno intermediate values between them, for instance between $\\nu_{dilute}$ and\n$\\nu_{melt}$.",
        "positive": "Molecular hydrodynamic theory of the velocity autocorrelation function: The velocity autocorrelation function (VACF) encapsulates extensive\ninformation about a fluid's molecular-structural and hydrodynamic properties.\nWe address the following fundamental question: How well can a purely\nhydrodynamic description recover the molecular features of a fluid as exhibited\nby the VACF? To this end, we formulate a bona fide hydrodynamic theory of the\ntagged-particle VACF for simple fluids. Our approach is distinguished from\nprevious efforts in two key ways: collective hydrodynamic modes are modeled by\n\\emph{linear} hydrodynamic equations; the fluid's static kinetic energy\nspectrum is identified as a necessary initial condition for the momentum\ncurrent correlation. Our formulation leads to a natural physical interpretation\nof the hydrodynamic VACF as a superposition of quasinormal hydrodynamic modes\nweighted commensurately with the static kinetic energy spectrum, which appears\nto be essential to bridging continuum hydrodynamical behavior and\ndiscrete-particle kinetics. Our methodology yields VACF calculations\nquantitatively on par with existing approaches for liquid noble gases and\nalkali metals; moreover, our hydrodynamic model for the self-intermediate\nscattering function extends the applicable domain to low densities where the\nSchmidt number is of order unity, enabling calculations for gases and\nsupercritical fluids."
    },
    {
        "anchor": "Mechanical disorder of sticky-sphere glasses. I. Effect of attractive\n  interactions: Recent literature indicates that attractive interactions between particles of\na dense liquid play a secondary role in determining its bulk mechanical\nproperties. Here we show that, in contrast with their apparent unimportance to\nthe bulk mechanics of dense liquids, attractive interactions can have a major\neffect on macro- and microscopic elastic properties of glassy solids. We study\nseveral broadly-applicable dimensionless measures of stability and mechanical\ndisorder in simple computer glasses, in which the relative strength of\nattractive interactions -- referred to as `glass stickiness' -- can be readily\ntuned. We show that increasing glass stickiness can result in the decrease of\nvarious quantifiers of mechanical disorder, on both macro- and microscopic\nscales, with a pair of intriguing exceptions to this rule. Interestingly, in\nsome cases strong attractions can lead to a reduction of the number density of\nsoft, quasilocalized modes, by up to an order of magnitude, and to a\nsubstantial decrease in their core size, similar to the effects of thermal\nannealing on elasticity observed in recent works. Contrary to the behavior of\ncanonical glass models, we provide compelling evidence indicating that the\nstabilization mechanism in our sticky-sphere glasses stems predominantly from\nthe self-organized depletion of interactions featuring large, \\emph{negative}\nstiffnesses. Finally, we establish a fundamental link between macroscopic and\nmicroscopic quantifiers of mechanical disorder, which we motivate via scaling\narguments. Future research directions are discussed.",
        "positive": "A Model for Hybrid Simulations of Molecular Dynamics and CFD: We propose a method for multi-scale hybrid simulations of molecular dynamics\n(MD) and computational fluid dynamics (CFD). In the method, usual lattice-mesh\nbased simulations are applied for CFD level, but each lattice is associated\nwith a small MD cell which generates a \"local stress\" according to a \"local\nflow field\" given from CFD instead of using any constitutive functions at CFD\nlevel. We carried out the hybrid simulations for some elemental flow problems\nof simple Lennard-Jones liquids and compared the results with those obtained by\nusual CFDs with a Newtonian constitutive relation in order to examine the\nvalidity of our hybrid simulation method. It is demonstrated that our hybrid\nsimulations successfully reproduced the correct flow behavior obtained from\nusual CFDs as far as the mesh size $\\Delta x$ and the time-step $\\Delta t$ of\nCFD are not too large comparing to the system size $l_{\\rm MD}$ and the\nsampling duration $t_{\\rm MD}$ of MD simulations performed at each time step of\nCFDs. Otherwise, simulations are affected by large fluctuations due to poor\nstatistical averages taken in the MD part. Properties of the fluctuations are\nanalyzed in detail."
    },
    {
        "anchor": "Threshold phenomena in erosion driven by subsurface flow: We study channelization and slope destabilization driven by subsurface\n(groundwater) flow in a laboratory experiment. The pressure of the water\nentering the sandpile from below as well as the slope of the sandpile are\nvaried. We present quantitative understanding of the three modes of sediment\nmobilization in this experiment: surface erosion, fluidization, and slumping.\nThe onset of erosion is controlled not only by shear stresses caused by\nsurfical flows, but also hydrodynamic stresses deriving from subsurface flows.\nThese additional forces require modification of the critical Shields criterion.\nWhereas surface flows alone can mobilize surface grains only when the water\nflux exceeds a threshold, subsurface flows cause this threshold to vanish at\nslopes steeper than a critical angle substantially smaller than the maximum\nangle of stability. Slopes above this critical angle are unstable to\nchannelization by any amount of fluid reaching the surface.",
        "positive": "Vapour-liquid phase diagram for an ionic fluid in a random porous medium: We study the vapour-liquid phase behaviour of an ionic fluid confined in a\nrandom porous matrix formed by uncharged hard sphere particles. The ionic fluid\nis modelled as an equimolar binary mixture of oppositely charged equisized hard\nspheres, the so-called restricted primitive model (RPM). Considering the\nmatrix-fluid system as a partly-quenched model, we develop a theoretical\napproach which combines the method of collective variables with the extension\nof the scaled-particle theory (SPT) for a hard-sphere fluid confined in a\ndisordered hard-sphere matrix. The approach allows us to formulate the\nperturbation theory using the SPT for the description of the thermodynamics of\nthe reference system. The phase diagrams of the RPM in matrices of different\nporosities and for different size ratios of matrix and fluid particles are\ncalculated in the random-phase approximation and also when the effects of\nhigher-order correlations between ions are taken into account. Both\napproximations correctly reproduce the basic effects of porous media on the\nvapour-liquid phase diagram, i.e., with a decrease of porosity the critical\npoint shifts toward lower fluid densities and lower temperatures and the\ncoexistence region is getting narrower. For the fixed matrix porosity, both the\ncritical temperature and the critical density increase with an increase of size\nof matrix particles and tend to the critical values of the bulk RPM."
    },
    {
        "anchor": "Hydrodynamic Interactions of Spherical Particles in A Fluid Confined by\n  A Rough And No-Slip Wall: In this article we develop a theoretical framework to study the hydrodynamic\ninteractions in the presence of a non-flat and no-slip boundary. We calculate\nthe influence of a small amplitude and sinusoidal deformations of a boundary\nwall in the self mobility and the two body hydrodynamic interactions for\nspherical particles. We show that the surface roughness enhances the self\nmobility of a sphere in a way that, for motion in front of a local hump of the\nsurface, the mobility strength decreases while it increases for the motion\nabove a local deep of the rough surface. The influence of the surface roughness\nin the two body hydrodynamic interactions is also analyzed numerically.",
        "positive": "Density distribution of particles upon jamming after an avalanche in a\n  2D silo: We present a complete analysis of the density distribution of particles in a\ntwo dimensional silo after discharge. Simulations through a pseudo-dynamic\nalgorithm are performed for filling and subsequent discharge of a plane silo.\nParticles are monosized hard disks deposited in the container and subjected to\na tapping process for compaction. Then, a hole of a given size is open at the\nbottom of the silo and the discharge is triggered. After a clogging at the\nopening is produced, and equilibrium is restored, the final distribution of the\nremaining particles at the silo is analyzed by dividing the space into cells\nwith different geometrical arrangements to visualize the way in which the\ndensity depression near the opening is propagated throughout the system. The\ndifferent behavior as a function of the compaction degree is discussed."
    },
    {
        "anchor": "Dynamics of microswimmers near a soft penetrable interface: Few simulations exist for microswimmers near deformable interfaces. Here, we\npresent numerical simulations of the hydrodynamic flows associated with a\nsingle microswimmer embedded in a binary fluid mixture. The two fluids demix,\nseparated by a penetrable and deformable interface that we assume to be\ninitially prepared in its planar ground-state. We find that the microswimmer\ncan either penetrate the interface, move parallel to it or bounce back off it.\nWe analyze how the trajectory depends on the swimmer type (pusher/puller) and\nthe angle of incidence with respect to the interface. Our simulations are\nperformed in a system with periodic boundary conditions, corresponding to an\ninfinite array of fluid interfaces. A puller reaches a steady state in which it\neither swims parallel to the interface or selects a perpendicular orientation,\nrepeatedly penetrating through the interface. In contrast, a pusher follows a\nbouncing trajectory between two interfaces. We discuss several examples in\nbiology in which swimmers penetrate soft interfaces. Our work can be seen as a\nhighly simplified model of such processes.",
        "positive": "A revisit of the density gradient theory and the mean field theory for\n  the vapor-liquid interface system: In this work we define a mean-field crossover generated by the Maxwell\nconstruction as the dividing interface for the vapor-liquid interface area. A\nhighly accurate density-profile equation is thus derived, which is physically\nfavorable and leads to reliable predictions of interfacial properties. By using\nthe density gradient theory and a mean-field equation of sate for the\nLennard-Jones fluid, we are able to extensively explore the interface system in\nterms of the Gibbs free energy, the Helmholtz free energy and heat capacity.\nThe results show that the mean-field dividing interface is the natural\nextension of the Widom line into the coexistence region. Hence the entire phase\nspace is coherently divided into liquid-like and gas-like regions in all three\n(temperature-pressure-volume) planes. Some unconventional behaviors are\nobserved for the intrinsic heat capacity, being positive in low temperature\nregion while negative in high temperature region. Finally, a complete picture\nof the mean-field equation of state is unfolded: all three solutions to a\nvapor-liquid equilibrium problem have their respective significances."
    },
    {
        "anchor": "Memory and aging effect in hierarchical spin orderings of stage-2\n  CoCl_{2} graphite intercalation compound: Stage-2 CoCl$_{2}$ graphite intercalation compound undergoes two magnetic\nphase transitions at $T_{cl}$ (= 7.0 K) and $T_{cu}$ (= 8.9 K). The aging\ndynamics of this compound is studied near $T_{cl}$ and $T_{cu}$. The\nintermediate state between $T_{cl}$ and $T_{cu}$ is characterized by a spin\nglass phase extending over ferromagnetic islands. A genuine thermoremnant\nmagnetization (TRM) measurement indicates that the memory of the specific spin\nconfigurations imprinted at temperatures between $T_{cl}$ and $T_{cu}$ during\nthe field-cooled (FC) aging protocol can be recalled when the system is\nre-heated at a constant heating rate. The zero-field cooled (ZFC) and TRM\nmagnetization is examined in a series of heating and reheating process. The\nmagnetization shows both characteristic memory and rejuvenation effects. The\ntime $(t)$ dependence of the relaxation rate\n$S_{ZFC}(t)=(1/H)$d$M_{ZFC}(t)$/d$\\ln t$ after the ZFC aging protocol with a\nwait time $t_{w}$, exhibits two peaks at characteristic times $t_{cr1}$ and\n$t_{cr2}$ between $T_{cl}$ and $T_{cu}$. An aging process is revealed as the\nstrong $t_{w}$ dependence of $t_{cr2}$. The observed aging and memory effect is\ndiscussed in terms of the droplet model.",
        "positive": "Velocity profiles in forced silo discharges: When a granular material is freely discharged from a silo through an orifice\nat its base, the flow rate remains constant throughout the discharge. However,\nit has been recently shown that, if the discharge is forced by an overweight,\nthe flow rate increases at the final stages of the discharge, in striking\ncontrast to viscous fluids [Madrid et al. Europhys. Lett. (2018)]. {Although\nthe general mechanism that drives this increase in the flow rate has been\ndiscussed, there exist yet a number of open questions regarding this\nphenomenon. One such questions is to what extent is the internal velocity\nprofile affected, beyond the trivial overall increase consistent with the\nincreasing flow rate.} We study via Discrete Element Method simulations the\ninternal velocity profiles during forced silo discharges and compare them with\nthose of free discharges. The changes in velocity profiles are somewhat subtle.\nInterestingly, during free discharges, while the velocity profiles are steady\nat the silo base and above a height equivalent to one silo diameter, there\nexists a transition region where the profile evolves in time, despite the\nconstant flow rate. In contrast, forced discharges present steady profiles at\nall heights of the granular column during the initial constant flow phase,\nfollowed by an overall increase of the velocities when the acceleration phase\ndevelops."
    },
    {
        "anchor": "Three-Dimensional Loop Extrusion: Loop extrusion convincingly describes how certain Structural Maintenance of\nChromosome (SMC) proteins mediate the formation of large DNA loops. Yet, most\nof the existing computational models cannot reconcile recent in vitro\nobservations showing that condensins can traverse each other, bypass large\nroadblocks and perform steps longer than its own size. To fill this gap, we\npropose a three-dimensional (3D) \"trans-grabbing\" model for loop extrusion\nwhich not only reproduces the experimental features of loop extrusion by one\nSMC complex, but also predicts the formation of so-called \"Z-loops\" via the\ninteraction of two or more SMCs extruding along the same DNA substrate. By\nperforming Molecular Dynamics simulations of this model we discover that the\nexperimentally observed asymmetry in the different types of Z-loops is a\nnatural consequence of the DNA tethering in vitro. Intriguingly, our model\npredicts this bias to disappear in absence of tethering and a third type of\nZ-loop, which has not yet been identified in experiments, to appear. Our model\nnaturally explains road-block bypassing and the appearance of steps larger than\nthe SMC size as a consequence of non-contiguous DNA grabbing. Finally, it is\nthe first to our knowledge to address how Z-loops and bypassing might occur in\na way that is broadly consistent with existing cis-only 1D loop extrusion\nmodels.",
        "positive": "Peeling an elastic film from a soft viscoelastic adhesive: experiments\n  and scaling laws: The functionality of adhesives relies on their response under the application\nof a load. Yet, it has remained a challenge to quantitatively relate the\nmacroscopic dynamics of peeling to the dissipative processes inside the\nadhesive layer. Here we investigate the peeling of a reversible adhesive made\nof a polymer gel, measuring the relationship between the peeling force, the\npeeling velocity, and the geometry of the interface at small-scale. Experiments\nare compared to a theory based on the linear viscoelastic response of the\nadhesive, augmented with an elastocapillary regularization approach. This\ntheory, fully quantitative in the limit of small surface deformations,\ndemonstrates the emergence of a \"wetting\" angle at the contact line and\nexhibits scaling laws for peeling which are in good agreement with the\nexperimental results. Our findings provide a new strategy for design of\nreversible adhesives, by quantitatively combining wetting, geometry and\ndissipation."
    },
    {
        "anchor": "Penetrating a granular medium by successive impacts: We consider the penetration dynamics of a vertical cylinder into a dry\ngranular medium subjected to successive impacts. The depth of the impactor\nbelow the free surface $z_N$ first evolves linearly with the impact number $N$\nand then follows a power-law evolution $z_N \\propto N^{1/3}$. The depth reached\nby the cylinder after a given number of impacts is observed to increase with\nthe impact energy but to decrease with its diameter and the density of the\ngranular medium. We develop a model that accounts for the quasi-static and\ninertial granular forces applying on the cylinder to rationalize our\nobservations. This approach reveals the existence of two intrusion regimes for\nlarge and small impact numbers, allowing all data to be rescaled on a master\ncurve. Then, we extend the study to the effect of sidewalls on the dynamics of\nthe impactor. We show that lateral confinement changes the dependence of the\nimpactor depth on the impact number $z_N (N)$. This effect is accounted for by\nconsidering the increase of the granular drag with the lateral confinement.",
        "positive": "Probing colloidal gels at multiple lengthscales: the role of\n  hydrodynamics: Colloidal gels are out-of-equilibrium structures, made up of a rarefied\nnetwork of colloidal particles. Comparing experiments to numerical simulations,\nwith hydrodynamic interactions switched off, we demonstrate the crucial role of\nthe solvent for gelation. Hydrodynamic interactions suppress the formation of\nlarger local equilibrium structures of closed geometry, and instead lead to the\nformation of highly anisotropic threads, which promote an open gel network. We\nconfirm these results with simulations which include hydrodynamics. Based on\nthree-point correlations, we propose a scale-resolved quantitative measure for\nthe anisotropy of the gel structure. We find a strong discrepancy for\ninterparticle distances just under twice the particle diameter between systems\nwith and without hydrodynamics, quantifying the role of hydrodynamics from a\nstructural point of view."
    },
    {
        "anchor": "Modeling hard-soft block copolymers as a liquid crystalline polymer: We report a new computational approach to model hard-soft block copolymers\nlike polyurea as a liquid crystalline polymer to understand their\nmicrostructural evolution due to mechanical loading. The resulting\nmicrostructure closely resembles the microstructure observed in polyurea. The\nstress-strain relations in uniaxial compression and tension loading obtained\nfrom the model are also in close quantitative agreement with the experimental\ndata for polyurea. We use the model to elucidate the evolution of the hard and\nthe soft domains during loading, which is consistent with the experimental\nmeasurements characterizing microstructural evolution in polyurea.",
        "positive": "Topological Sound and Flocking on Curved Surfaces: Active systems on curved geometries are ubiquitous in the living world. In\nthe presence of curvature orientationally ordered polar flocks are forced to be\ninhomogeneous, often requiring the presence of topological defects even in the\nsteady state due to the constraints imposed by the topology of the underlying\nsurface. In the presence of spontaneous flow the system additionally supports\nlong-wavelength propagating sound modes which get gapped by the curvature of\nthe underlying substrate. We analytically compute the steady state profile of\nan active polar flock on a two-sphere and a catenoid, and show that curvature\nand active flow together result in symmetry protected topological modes that\nget localized to special geodesics on the surface (the equator or the neck\nrespectively). These modes are the analogue of edge states in electronic\nquantum Hall systems and provide unidirectional channels for information\ntransport in the flock, robust against disorder and backscattering."
    },
    {
        "anchor": "Kullback--Leibler Divergence of a Freely Cooling Granular Gas: Finding the proper entropy-like Lyapunov functional associated with the\ninelastic Boltzmann equation for an isolated freely cooling granular gas is a\nstill unsolved challenge. The original $H$-theorem hypotheses do not fit here\nand the $H$-functional presents some additional measure problems that are\nsolved by the Kullback--Leibler divergence (KLD) of a reference velocity\ndistribution function from the actual distribution. The right choice of the\nreference distribution in the KLD is crucial for the latter to qualify or not\nas a Lyapunov functional, the asymptotic \"homogeneous cooling state\" (HCS)\ndistribution being a potential candidate. Due to the lack of a formal proof far\nfrom the quasielastic limit, the aim of this work is to support this conjecture\naided by molecular dynamics simulations of inelastic hard disks and spheres in\na wide range of values for the coefficient of restitution ($\\alpha$) and for\ndifferent initial conditions. Our results reject the Maxwellian distribution as\na possible reference, whereas they reinforce the HCS one. Moreover, the KLD is\nused to measure the amount of information lost on using the former rather than\nthe latter, revealing a non-monotonic dependence with $\\alpha$.",
        "positive": "Roles of energy dissipation in a liquid-solid transition of\n  out-of-equilibrium systems: Self-organization of active matter as well as driven granular matter in\nnon-equilibrium dynamical states has attracted considerable attention not only\nfrom the fundamental and application viewpoints but also as a model to\nunderstand the occurrence of such phenomena in nature. These systems share\ncommon features originating from their intrinsically out-of-equilibrium nature.\nIt remains elusive how energy dissipation affects the state selection in such\nnon-equilibrium states. As a simple model system, we consider a non-equilibrium\nstationary state maintained by continuous energy input, relevant to industrial\nprocessing of granular materials by vibration and/or flow. More specifically,\nwe experimentally study roles of dissipation in self-organization of a driven\ngranular particle monolayer. We find that the introduction of strong\ninelasticity entirely changes the nature of the liquid-solid transition from\ntwo-step (nearly) continuous transitions (liquid-hexatic-solid) to a strongly\ndiscontinuous first-order-like one (liquid-solid), where the two phases with\ndifferent effective temperatures can coexist, unlike thermal systems, under a\nbalance between energy input and dissipation. Our finding indicates a pivotal\nrole of energy dissipation and suggests a novel principle in the\nself-organization of systems far from equilibrium. A similar principle may\napply to active matter, which is another important class of out-of-equilibrium\nsystems. On noting that interaction forces in active matter, and particularly\nin living systems, are often non-conservative and dissipative, our finding may\nalso shed new light on the state selection in these systems."
    },
    {
        "anchor": "Motion of an active particle in a linear concentration gradient: Janus particles self-propel by generating local tangential concentration\ngradients along their surface. These gradients are present in a thin layer\nwhose thickness is small compared to the particle size. Chemical asymmetry\nalong the surface is a prerequisite to generate tangential chemical gradient,\nwhich gives rise to diffusioosmotic flows in a thin region around the particle.\nThis results in an effective slip on the particle surface. This slip results in\nthe observed \"swimming\" motion of a freely suspended particle even in the\nabsence of externally imposed concentration gradients.Motivated by the\nchemotactic behaviour of their biological counterparts(such as sperm cells,\nneutrophils, macrophages, bacteria etc.), which sense and respond to external\nchemical gradients, the current work aims at developing a theoretical framework\nto study the motion of a Janus particle in an externally imposed linear\nconcentration gradient. The external gradient along with the self-generated\nconcentration gradient determines the swimming velocity and orientation of the\nparticle.The dominance of each of these effects is characterised by a\nnon-dimensional activity number A. The surface of Janus particle is modelled as\nhaving a different activity and mobility coefficient on the two halves.Using\nLorentz Reciprocal theorem, an analytical expression for the rotational and\ntranslational velocity is obtained. The analytical framework helps us divide\nthe parameter space of surface activity and mobility into four regions where\nthe particle exhibits different trajectories.",
        "positive": "Conditions for one-dimensional supersonic flow of quantum gases: One can use transsonic Bose-Einstein condensates of alkali atoms to establish\nthe laboratory analog of the event horizon and to measure the acoustic version\nof Hawking radiation. We determine the conditions for supersonic flow and the\nHawking temperature for realistic condensates on waveguides where an external\npotential plays the role of a supersonic nozzle. The transition to supersonic\nspeed occurs at the potential maximum and the Hawking temperature is entirely\ndetermined by the curvature of the potential."
    },
    {
        "anchor": "Instabilities of micro-phase separated Coulombic systems in constant\n  electric fields: Mixtures of near-symmetric oppositely charged components with strong\nattractive short range interactions exhibit ordered lamellar phases at low\ntemperatures. In the strong segregation limit the state of these systems can be\ndescribed by the location of the interfaces between the components. It has\npreviously been shown that these systems are stable against small deformations\nof the interfaces. We examine their stability in the presence of a uniform\nelectric field. When the field is perpendicular to the lamellae, the system is\nunstable against long wavelength deformations for all non-zero values of the\nexternal field. A field parallel to the lamellae produces deformed but\npersistent interfaces. In a finite thickness system, onset of an external\nperpendicular field modifies the ground state. Flow between the old and new\nground states requires the destruction of the original interfaces; this\ndestruction proceeds through the instabilities identified in the bulk case. We\nexamine the possibility of dynamical stabilization of structures by means of\noscillating fields.",
        "positive": "Towards a density functional description of liquid pH2: A finite-temperature density functional approach to describe the properties\nof parahydrogen in the liquid-vapor coexistence region is presented. The first\nproposed functional is zero-range, where the density-gradient term is adjusted\nso as to reproduce the surface tension of the liquid-vapor interface at low\ntemperature. The second functional is finite-range and, while it is fitted to\nreproduce bulk pH2 properties only, it is shown to yield surface properties in\ngood agreement with experiments. These functionals are used to study the\nsurface thickness of the liquid-vapor interface, the wetting transition of\nparahydrogen on a planar Rb model surface, and homogeneous cavitation in bulk\nliquid pH2."
    },
    {
        "anchor": "Effective creases and contact angles between membrane domains with high\n  spontaneous curvature: We show that the short-scale elastic distortions that are excited in the\nvicinity of the joint between different lipidic membrane domains (at a scale of\n\\~10 nm) may produce a \"crease\" from the point of view of the standard elastic\ndescription of membranes, i.e., an effective discontinuity in the membrane\nslope at the level of Helfrich's theory. This \"discontinuity\" may be accounted\nfor by introducing a line tension with an effective angular dependence. We show\nthat domains bearing strong spontaneous curvatures, such as biological rafts,\nshould exhibit creases with a finite contact-angle, almost prescribed,\ncorresponding to a steep extremum of the line energy. Finite contact-angles\nmight also occur in symmetric membranes from the recruitment of impurities at\nthe boundary.",
        "positive": "Dynamics of bacterial flow: Emergence of spatiotemporal coherent\n  structures: We propose a simple model of self-propelled particles to show that coherent\nstructures, such as jets and swirls, can arise from a plausible microscopic\nmechanisms: (i) the elongated shape of the self-propelled particles with (ii)\nthe hardcore interactions among them. We demonstrate via computer simulation\nthat these coherent structures, which emerge at sufficiently high densities of\nparticles, have characteristics that are similar to those observed in recent\nexperiments in bacteria baths."
    },
    {
        "anchor": "Transient nucleation driven by solvent evaporation: We theoretically investigate homogeneous crystal nucleation in a solution\ncontaining a solute and a volatile solvent. The solvent evaporates from the\nsolution, thereby continuously increasing the concentration of the solute. We\nview it as an idealized model for the far-out-of-equilibrium conditions present\nduring the liquid-state manufacturing of organic electronic devices. Our model\nis based on classical nucleation theory, taking the solvent to be a source of\nthe transient conditions in which the solute drops out of solution. Other than\nthat, the solvent is not directly involved in the nucleation process itself. We\napproximately solve the kinetic master equations using a combination of Laplace\ntransforms and singular perturbation theory, providing an analytical expression\nfor the nucleation flux, predicting that (i) the nucleation flux lags slightly\nbehind a commonly used quasi-steady-state approximation, an effect that is\ngoverned by two counteracting effects originating from the solvent evaporation:\nwhile a faster evaporation rate results in an increasingly larger influence of\nthe lag time on the nucleation flux, this lag time itself we find to decrease\nwith increasing evaporation rate, (ii) the nucleation flux and the\nquasi-steady-state nucleation flux are never identical, except trivially in the\nstationary limit and (iii) the initial induction period of the nucleation flux,\nwhich we characterize with a generalized induction time, decreases weakly with\nthe evaporation rate. This indicates that the relevant time scale for\nnucleation also decreases with increasing evaporation rate. Our analytical\ntheory compares favorably with results from numerical evaluation of the\ngoverning kinetic equations.",
        "positive": "Tension-controlled switch between collective actuations in active solids: The recent finding of collective actuation in active solids, namely solids\nembedded with active units, opens the path towards multifunctional materials\nwith genuine autonomy. In such systems, collective dynamics emerge\nspontaneously and little is known about the way to control or drive them. Here,\nwe combine the experimental study of centimetric model active solids, the\nnumerical study of an agent based model and theoretical arguments to reveal how\nmechanical tension can serve as a general mechanism for switching between\ndifferent collective actuation regimes in active solids. We further show the\nexistence of a hysteresis when varying back and forth mechanical tension,\nhighlighting the non-trivial selectivity of collective actuations."
    },
    {
        "anchor": "Hydrogen Bond Dynamics Near A Micellar Surface: Origin of the Universal\n  Slow Relaxation at Complex Aqueous Interfaces: The dynamics of hydrogen bonds among water molecules themselves and with the\npolar head groups (PHG) at a micellar surface have been investigated by long\nmolecular dynamics simulations. The lifetime of the hydrogen bond between a PHG\nand a water molecule is found to be much longer than that between any two water\nmolecules, and is likely to be a general feature of hydrophilic surfaces of\norganized assemblies. Analyses of individual water trajectories suggest that\nwater molecules can remain bound to the micellar surface for more than a\nhundred picosecond. The activation energy for such a transition from the bound\nto a free state for the water molecules is estimated to be about 3.5kcal/mole.",
        "positive": "Dynamics of hard-sphere suspension using Dynamic Light Scattering and\n  X-Ray Photon Correlation Spectroscopy: dynamics and scaling of the\n  Intermediate Scattering Function: Intermediate Scattering Functions (ISF's) are measured for colloidal hard\nsphere systems using both Dynamic Light Scattering (DLS) and X-ray Photon\nCorrelation Spectroscopy (XPCS). We compare the techniques, and discuss the\nadvantages and disadvantages of each. Both techniques agree in the overlapping\nrange of scattering vectors. We investigate the scaling behaviour found by\nSegre and Pusey [1] but challenged by Lurio et al. [2]. We observe a scaling\nbehaviour over several decades in time but not in the long time regime.\nMoreover, we do not observe long time diffusive regimes at scattering vectors\naway from the peak of the structure factor and so question the existence of a\nlong time diffusion coefficients at these scattering vectors."
    },
    {
        "anchor": "Cross Correlators and Galilean Invariance in Fluctuating Ideal Gas\n  Lattice Boltzmann Simulations: We analyze the Lattice Boltzmann method for the simulation of fluctuating\nhydrodynamics by Adhikari et al. [Europhys. Lett. 71, 473 (2005)] and find that\nit shows excellent agreement with theory even for small wavelengths as long as\na stationary system is considered. This is in contrast to other finite\ndifference and older lattice Boltzmann implementations that show convergence\nonly in the limit of large wavelengths. In particular cross correlators vanish\nto less than 0.5%. For larger mean velocities, however, Galilean invariance\nviolations manifest themselves through errors of a magnitude similar to those\nof the earlier implementations.",
        "positive": "Swelling dynamics of surface-attached hydrogel thin films in vapor flows: Hydrogel coatings absorb water vapor - or other solvents - and, as such, are\ngood candidates for antifog applications. In the present study, the transfer of\nvapor from the atmosphere to hydrogel thin films is measured in a situation\nwhere water vapor flows alongside the coating which is set to a temperature\nlower that the ambient temperature. The effect of the physico-chemistry of the\nhydrogel film on the swelling kinetics is particularly investigated. By using\nmodel thin films of surface-grafted polymer networks with controlled thickness,\nvaried crosslinks density, and varied affinity for water, we were able to\ndetermine the effect of the film hygroscopy on the dynamics of swelling of the\nfilm. These experimental results are accounted for by a diffusion-advection\nmodel that is supplemented with a boundary condition at the hydrogel surface:\nwe show that the latter can be determined from the equilibrium sorption\nisotherms of the polymer films. Altogether, this paper offers a predictive tool\nfor the swelling kinetics of any hydrophilic hydrogel thin films."
    },
    {
        "anchor": "A new water anomaly: the temperature dependence of the proton mean\n  kinetic energy: The mean kinetic energy of protons in water is determined by Deep Inelastic\nNeutron Scattering experiments, performed above and below the temperature of\nmaximum density and in the supercooled phase. The temperature dependence of\nthis energy shows an anomalous behavior, as it occurs for many water\nproperties. In particular two regions of maximum kinetic energy are identified:\nthe first one, in the supercooled phase in the range 269 K - 272 K, and a\nsecond one above 273 K. In both these regions the measured proton kinetic\nenergy exceedes the theoretical prediction based on a semi-classical model.\nNoteworthy, the proton mean kinetic energy has a maximum at 277 K, the\ntemperature of the maximum density of water. In the supercooled metastable\nphase the measured mean kinetic energy and the proton momentum distribution\nclearly indicate proton delocalization between two H-bonded oxygens.",
        "positive": "Bending of bilayers with general initial shapes: We present a simple discrete formula for the elastic energy of a bilayer. The\nformula is convenient for rapidly computing equilibrium configurations of\nactuated bilayers of general initial shapes. We use maps of principal\ncurvatures and minimum-curvature direction fields to analyze configurations. We\nfind good agreement between the computations and an approximate analytical\nsolution for the case of a rectangular bilayer. For more general shapes (simple\npolyiamonds), we find a range of typical bending behaviors: overall bending\ndirections along longest and shortest dimensions, inward bending at corners,\ncurvature intensification near boundaries, and conical bending and partitioned\nbending zones in some cases."
    },
    {
        "anchor": "Differential Capacitance of Electric Double Layers: A Poisson-Bikerman\n  Formula: We propose a Poisson-Bikerman (PBik) formula for calculating the differential\ncapacitance (DC) of electrical double layers (EDLs) in aqueous electrolytes or\nionic liquids. The PBik theory is a generalization of the classical\nPoisson-Boltzmann theory to include different steric energies of\ndifferent-sized ions and water similar to different electrical energies for\ndifferent-charged ions. Water and ions with interstitial voids in this\nmolecular mean field theory have their physical volumes as they do in molecular\ndynamics simulations. The PBik formula derived from Fermi distributions of ions\nand water in arbitrary shape and volume reduces to the Bikerman-Freise formula\nderived from the lattice model of equal-sized ions. The DC curves predicted by\nthe Gouy-Chapman formula are U-shaped (for point-like ions with zero volume and\nvery dilute solutions). The curves change from U shape to camel shape\n(Bactrian) and then to bell shape (for finite size ions) as the volume fraction\nof ions and water changes from zero to medium value then to large value. The\ntransition is characterized by critical and inflection voltages in terms of the\nparticle volume fraction. These voltages determine steric and electrical\nenergies that describe the space/charge competition and saturation properties\nof ions and water packed in the condensed layer of EDLs under high field\nconditions. Steric energy is as important as electrical energy in these\nconditions. PBik computes symmetric DC curves from delicately balanced steric\ninteractions of asymmetric-size ions and water like the experimental data of\nKPF6 in aqueous solution. It computes asymmetric curves and captures delicately\nbalanced steric or electrical interactions of ions having different volumes or\ncharges in ionic liquids.",
        "positive": "Self-diffusion in sheared colloidal suspensions: violation of\n  fluctuation-dissipation relation: Using memory-function formalism we show that in sheared colloidal suspensions\nthe fluctuation-dissipation theorem for self-diffusion, i.e. Einstein's\nrelation between self-diffusion and mobility tensors, is violated and propose a\nnew way to measure this violation in Brownian Dynamics simulations. We derive\nmode-coupling expressions for the tagged particle friction tensor and for an\neffective, shear-rate dependent temperature."
    },
    {
        "anchor": "Texture-induced modulations of friction force: the fingerprint effect: Dry solid friction is often accompanied by force modulations originating from\nstick-slip instabilities. Here a distinct, quasi-static mechanism is evidenced\nleading to quasi-periodic force oscillations during sliding contact between an\nelastomer block, whose surface is patterned with parallel grooves, and finely\nabraded glass slides. The dominant oscillation frequency is set by the ratio\nbetween the sliding velocity and the period of the grooves. A mechanical model\nis proposed that provides a quantitative prediction for the amplitude of the\nforce modulations as a function of the normal load, the period of the grooves\nand the roughness characteristics of the substrate. The model's main ingredient\nis the non-linearity of the friction law. Since such non-linearity is\nubiquitous for soft solids, this \"fingerprint effect\" should be relevant to a\nlarge class of frictional configurations and might in particular have important\nconsequences in human (or humanoid) active digital touch.",
        "positive": "Spatio-temporal structures in sheared polymer systems: We investigate spatio-temporal structures in sheared polymer systems by\nsolving a time-dependent Ginzburg-Landau model in two dimensions. (i) In\npolymer solutions above the coexistence curve, crossover from linear to\nnonlinear regimes occurs with increasing the shear rate. In the nonlinear\nregime the solution behaves chaotically with large-amplitude composition\nfluctuations. A characteristic heterogeneity length is calculated in the\nnonlinear regime. (ii) We also study dynamics of shear-band structures in\nwormlike micellar solutions under the condition of fixed stress. The average\nshear rate exhibits large temporal fluctuations with occurrence of large\ndisturbances in the spatial structures."
    },
    {
        "anchor": "On the location of the excess wing relative to the a-loss peak in the\n  susceptibility spectra from simulations with the swap Monte Carlo algorithm: An advance was made by Guiselin et al. [arXiv:2103.01569 (2021)] in molecular\ndynamics simulations of the equilibrium dynamics of supercooled liquids near\nthe experimental glass transition by utilizing the giant equilibration speedup\nprovided by the swap Monte Carlo algorithm. The found emergence of a power law\nin relaxation spectra at lower temperatures on the high frequency flank of the\nalpha-loss peak in analogy to the excess wings observed experimentally in\nmolecular glass-formers. Their remarkable finding leads to the question of\nwhere the excess wing is located relative to the alpha-loss peak in the\nsusceptibility spectrum. I provide an answer by identifying the excess wing as\nthe unresolved Johari-Goldstein (JG) b-relaxation and using the reciprocal of\nits relaxation time tau_JG to assess the location of the excess wing. The\nCoupling Model (CM) has a history of being successful in determining\napproximately the values of tau_JG(T) in molecular liquids whether the JG\nbeta-relaxation is resolved or not (i.e., excess wing). It is applied to the\nsimulation data and the results of tau_JG(T) successfully account for the\nlocations of the excess wings in the simulation spectra at different\ntemperatures. The time evolution of the dynamics of the distribution of\nprocesses composing the JG b-relaxation suggested by the CM based on\nexperimental data in molecular glass-formers are in agreement with that given\nby Guiselin et al. from simulations of a size-polydisperse mixture of N soft\nspheres interacting with a repulsive power law pair potential. The agreement\nbrings their results closer to experimental data of real molecular\nglass-formers.",
        "positive": "Langevin analogy between particle trajectories and polymer\n  configurations: A diffusive trajectory drawn by the generalized Langevin equation (GLE) for a\ncolloidal particle evokes a random fractal of a static polymer configuration.\nThis article proposes a static GLE-like description that enables the generation\nof a single configuration of a polymer chain with the noise formulated to\nsatisfy the static fluctuation-response relation (FRR) along a one-dimensional\nchain structure but not along a temporal coordinate. A remarkable point is\nqualitative differences and similarities in the FRR formulation between the\nstatic and the dynamical GLEs. Guided by the static FRR, we further make\nanalogous arguments in the light of stochastic energetics and the steady-state\nfluctuation theorem."
    },
    {
        "anchor": "Neutral versus charged defect patterns in curved crystals: Characterizing the complex spectrum of topological defects in ground states\nof curved crystals is a long-standing problem with wide implications, from the\nmathematical Thomson problem to diverse physical realizations, including\nfullerenes and particle-coated droplets. While the excess number of\n\"topologically-charged\" 5-fold disclinations in a closed, spherical crystal is\nfixed, here, we study the elementary transition from defect-free, flat crystals\nto curved-crystals possessing an excess of \"charged\" disclinations in their\nbulk. Specifically, we consider the impact of topologically-neutral patterns of\ndefects -- in the form of multi-dislocation chains or \"scars\" stable for small\nlattice spacing -- on the transition from neutral to charged ground-state\npatterns of a crystalline cap bound to a spherical surface. Based on the\nasymptotic theory of caps in continuum limit of vanishing lattice spacing, we\nderive the morphological phase diagram of ground state defect patterns, spanned\nby surface coverage of the sphere and forces at the cap edge. For the singular\nlimit of zero edge forces, we find that scars reduce (by half) the threshold\nsurface coverage for excess disclinations. Even more significant, scars flatten\nthe geometric dependence of excess disinclination number on Gaussian curvature,\nleading to a transition between stable \"charged\" and \"neutral\" patterns that\nis, instead, critically sensitive to the compressive vs. tensile nature of\nboundary forces on the cap.",
        "positive": "Aging in attraction-driven colloidal glasses: Aging in an attraction-driven colloidal glass is studied by computer\nsimulations. The system is equilibrated without attraction and instantaneously\n``quenched'', at constant colloid volume fraction, to one of two states beyond\nthe glass transition; one is close to the transition, and the other one deep in\nthe glass. The evolution of structural properties shows that bonds form in the\nsystem, increasing the local density, creating density deficits (holes)\nelsewhere. This process slows down with the time elapsed since the quench. As a\nconsequence of bond formation, there is a slowing down of the dynamics, as\nmeasured by the mean squared displacement and the density, bond, and\nenvironment correlation functions. The density correlations can be\ntime-rescaled to collapse their long time (structural) decay. The time scale\nfor structural relaxation shows for both quenches a super-linear dependence on\nwaiting time; it grows faster than the bond lifetime, showing the collective\norigin of the transition. At long waiting times and high attraction strength,\nwe observe {\\rem completely} arrested dynamics for more than three decades in\ntime, although individual bonds are not permanent on this time scale. The\nlocalization length decreases as the state moves deeper in the glass; the\nnon-ergodicity parameter oscillates in phase with the structure factor. Our\nmain results are obtained for systems with a barrier in the pair potential that\ninhibits phase separation. However, when this barrier is removed for the case\nof a deep quench, we find changes in the static structure but almost none in\nthe dynamics. Hence our results for the aging behavior remain relevant to\nexperiments in which the glass transition competes with phase separation."
    },
    {
        "anchor": "Dense bidisperse suspensions under non-homogenous shear: We study the rheological behaviour of bidisperse suspensions in three\ndimensions under a non-uniform shear flow, made by the superimposition of a\nlinear shear and a sinusoidal disturbance. Our results show that i) only a\nstreamwise disturbance in the shear-plane alters the suspension dynamics by\nsubstantially reducing the relative viscosity, ii) with the amplitude of the\ndisturbance determining a threshold value for the effect to kick-in and its\nwavenumber controlling the amount of reduction and which of the two phases is\naffected. We show that, iii) the rheological changes are caused by the\neffective separation of the two phases, with the large or small particles\nlayering in separate regions. We provide a physical explanation of the phase\nseparation process and of the conditions necessary to trigger it. We test the\nresults in the whole flow curve, and we show that the mechanism remains\nsubstantially unaltered, with the only difference being the nature of the\ninteractions between particles modified by the phase separation.",
        "positive": "Morphological Similarities between Single-walled Nanotubes and Tubelike\n  Structures of Polymers with Strong Adsorption Affinity to Nanowires: In their tubelike phase, nanowire-adsorbed polymers exhibit strong structural\nsimilarities to morphologies known from single-walled carbon (hexagonal) and\nboron (triangular) nanotubes. Since boron/boron nitride tubes require some\ndisorder for stability the triangular polymer tubes provide a closer analog to\nthe carbon tubes. By means of computer simulations of both two and three\ndimensional versions of a coarse-grained bead-spring model for the polymers, we\ninvestigate their structural properties and make a detailed comparison with\nstructures of carbon nanotubes."
    },
    {
        "anchor": "Suspensions of viscoelastic capsules: effect of membrane viscosity on\n  transient dynamics: Membrane viscosity is known to play a central role in the transient dynamics\nof isolated viscoelastic capsules by decreasing their deformation, inducing\nshape oscillations and reducing the loading time, that is, the time required to\nreach the steady-state deformation. However, for dense suspensions of capsules,\nour understanding of the influence of the membrane viscosity is minimal. In\nthis work, we perform a systematic numerical investigation based on coupled\nimmersed boundary -- lattice Boltzmann (IB-LB) simulations of viscoelastic\nspherical capsule suspensions in the non-inertial regime. We show the effect of\nthe membrane viscosity on the transient dynamics as a function of volume\nfraction and capillary number. Our results indicate that the influence of\nmembrane viscosity on both deformation and loading time strongly depends on the\nvolume fraction in a non-trivial manner: dense suspensions with large surface\nviscosity are more resistant to deformation but attain loading times that are\ncharacteristic of capsules with no surface viscosity, thus opening the\npossibility to obtain richer combinations of mechanical features.",
        "positive": "Salt Effects on Ionic Conductivity Mechanisms in Ethylene Carbonate\n  Electrolytes: Interplay of Viscosity and Ion-ion Relaxations: The intricate role of shear viscosity and ion-pair relaxations on ionic\nconductivity mechanisms and the underlying changes induced by salt\nconcentration ($c$) in organic liquid electrolytes remain poorly understood\ndespite their widespread technological importance. Using molecular dynamics\nsimulations employing nonpolarizable force fields for $c$ ranging between\n10$^{-3}$ to 101 M, we show that the low and high $c$ regimes of the EC-LiTFSI\nelectrolytes are distinctly characterized by $\\eta\\sim\\tau_c^{1/2}$ and\n$\\eta\\sim\\tau_c^{1}$, where $\\eta$ and $\\tau_c$ are shear viscosity and\ncation-anion relaxation timescales, respectively. Our extensive simulations and\nanalyses suggest a universal relationship between the ionic conductivity and c\nas $\\sigma(c)\\sim c^{\\alpha}e^{-c/c_{0}} (\\alpha>0)$. The proposed relationship\nconvincingly explains the ionic conductivity over a wide range of $c$, where\nthe term $c^\\alpha$ accounts for the uncorrelated motion of ions and\n$e^{-c/c_0}$ captures the salt-induced changes in shear viscosity. Our\nsimulations suggest vehicular mechanism to be dominant at low $c$ regime which\ntransition into a Grotthuss mechanism at high $c$ regime, where structural\nrelaxation is the dominant form of ion transport mechanism. Our findings shed\nlight on some of the fundamental aspects of the ion conductivity mechanisms in\nliquid electrolytes, offering insights into optimizing the ion transport in\nEC-LiTFSI electrolytes."
    },
    {
        "anchor": "Emergence and persistence of flow inhomogeneities in the yielding and\n  fluidization of dense soft solids: The response to shear of the dense soft solids features a stress overshoot\nand a persistent shear banding before reaching a homogeneously flowing state.\nIn 3D large scale simulations we analyze the time required for the onset of\nhomogeneous flow, the normal stresses and structural signatures at different\nshear rates and in different flow geometries, finding that the stress\novershoot, the shear band formation and its persistence are controlled by the\npresence of overconstrained microscopic domains in the initially solid samples.\nBeing able to identify such domains in our model by prevalently icosahedrally\npacked regions, we show that they allow for stress accumulation during the\nstress overshoot and that their structural reorganization controls the\nemergence and the persistence of the shear banding.",
        "positive": "Excess wings and asymmetric relaxation spectra in a facilitated trap\n  model: In a recent computer study, we have shown that the combination of spatially\nheterogeneous dynamics and kinetic facilitation provides a microscopic\nexplanation for the emergence of excess wings in deeply supercooled liquids.\nMotivated by these findings, we construct a minimal empirical model to describe\nthis physics and introduce dynamic facilitation in the trap model, which was\ninitially developed to capture the thermally-activated dynamics of glassy\nsystems. We fully characterise the relaxation dynamics of this facilitated trap\nmodel varying the functional form of energy distributions and the strength of\ndynamic facilitation, combining numerical results and analytic arguments.\nDynamic facilitation generically accelerates the relaxation of the deepest\ntraps, thus making relaxation spectra strongly asymmetric, with an apparent\n\"excess\" signal at high frequencies. For well-chosen values of the parameters,\nthe obtained spectra mimic experimental results for organic liquids displaying\nan excess wing. Overall, our results identify the minimal physical ingredients\nneeded to describe excess processes in relaxation spectra of supercooled\nliquids."
    },
    {
        "anchor": "Creating bulk ultrastable glasses by random particle bonding: A recent breakthrough in glass science has been the synthesis of ultrastable\nglasses via physical vapor deposition techniques. These samples display\nenhanced thermodynamic, kinetic and mechanical stability, with important\nimplications for fundamental science and technological applications. However,\nthe vapor deposition technique is limited to atomic, polymer and organic\nglass-formers and is only able to produce thin film samples. Here, we propose a\nnovel approach to generate ultrastable glassy configurations in the bulk, via\nrandom particle bonding, and using computer simulations we show that this\nmethod does indeed allow for the production of ultrastable glasses. Our\ntechnique is in principle applicable to any molecular or soft matter system,\nsuch as colloidal particles with tunable bonding interactions, thus opening the\nway to the design of a large class of ultrastable glasses.",
        "positive": "Using Car-Parrinello simulations and microscopic order descriptors to\n  reveal two locally favored structures with distinct molecular dipole moments\n  and dynamics in ambient liquid water: Water is essential for life and technological applications, mainly for its\nunique thermodynamic and dynamic properties, often anomalous or\ncounterintuitive. These anomalies result from the hydrogen-bonds fluctuations,\nas evidenced by studies for supercooled water. However, it is difficult to\ncharacterize these fluctuations under ambient conditions. Here, we fill this\nknowledge gap thanks to the Car-Parrinello ab initio molecular dynamics (MD)\nsimulation technique. We calculate the local structural order parameter\n{\\zeta}, quantifying the coordination shells separation, and find two\nlocally-favored structures or states: High-{\\zeta} and Low-{\\zeta}. On average,\nHigh-{\\zeta} molecules have a tetrahedral arrangement, with four hydrogen\nbonds, and the first and the second coordination shell well separated. The\nLow-{\\zeta} molecules are less connected, partially merging the first and the\nsecond shells. The appearance of isosbestic points in the radial distribution\nfunctions and the collective density fluctuations at different length scales\nand timescales reveal that the two-state model, consistent with available\nexperimental data for supercooled water, also holds under ambient conditions,\nas we confirm by analyzing the vibrational spectrum of both types of water\nmolecules. Significant consequences of the structural differences between the\ntwo states are that High-{\\zeta} molecules have a dipole moment 6 % higher than\nLow-{\\zeta}. At the same time, Low-{\\zeta} structures are more disordered and\nwith more significant angular fluctuations. These differences are also\nreflected in the dynamics under ambient conditions. The Low-{\\zeta} molecules\ndecorrelate their reorientation faster than High-{\\zeta} and merge their\ncoordination shells within 0.2 ps, while the High-{\\zeta} preserve the shell\nseparation for longer times."
    },
    {
        "anchor": "Inclusions, Boundaries and Disorder in Scalar Active Matter: Active systems are driven out of equilibrium by exchanging energy and\nmomentum with their environment. This endows them with anomalous mechanical\nproperties that we review in this colloquium for the case of dry scalar active\nmatter, which has attracted considerable attention. These unusual properties\nlead to a rich physics when active fluids are in contact with boundaries,\ninclusions, tracers, or disordered potentials. Indeed, studies of the\nmechanical pressure of active fluids and of the dynamics of passive tracers\nhave shown that active systems impact their environment in non-trivial ways,\nfor example, by propelling and rotating anisotropic inclusions. Conversely, the\nlong-ranged density and current modulations induced by localized obstacles show\nhow the environment can have a far-reaching impact on active fluids. This is\nbest exemplified by the propensity of bulk and boundary disorder to destroy\nbulk phase separation in active matter, showing active systems to be much more\nsensitive to their surroundings than passive ones. This colloquium aims at\nproviding a unifying perspective on the rich interplay between active systems\nand their environments.",
        "positive": "Accounting for inertia effects to access the high-frequency\n  microrheology of viscoelastic fluids: We study the Brownian motion of microbeads immersed in water and in a\nviscoelastic wormlike micelles solution by optical trapping interferometry and\ndiffusing wave spectroscopy. Through the mean-square displacement obtained from\nboth techniques, we deduce the mechanical properties of the fluids at high\nfrequencies by explicitly accounting for inertia effects of the particle and\nthe surrounding fluid at short time scales. For wormlike micelle solutions, we\nrecover the 3/4 scaling exponent for the loss modulus over two decades in\nfrequency as predicted by the theory for semiflexible polymers."
    },
    {
        "anchor": "Correlation between diffusion and coherence in Brownian motion on a\n  tilted periodic potential: The paper studies the overdamped motion of Brownian particles in a tilted\nsawtooth potential. The dependencies of the diffusion coefficient and coherence\nlevel of Brownian transport on temperature, tilting force, and the shape of the\npotential are analyzed. It is demonstrated that at low temperatures the\ncoherence level of Brownian transport stabilizes in the extensive domain of the\ntilting force where the value of the Peclet factor is Pe=2. This domain\ncoincides with the one where the enhancement of the diffusion coefficient\nversus the tilting force is the most rapid. The necessary and sufficient\nconditions for the non-monotonic behaviour of the diffusion coefficient as a\nfunction of temperature are found. The effect of the acceleration of diffusion\nby bias and temperature is demonstrated to be very sensitive to the value of\nthe asymmetry parameter of the potential.",
        "positive": "Calculation of the Micellar Structure of Polymer Surfactant Based on the\n  Density Functional Theory: Amphiphilic block copolymer solutions form various micellar structures\nincluding micelles and vesicles. We applied the density functional theory for\nblock copolymers which we have proposed to amphiphilic block copolymer systems.\nThe 3 dimensional simulation for AB diblock copolymer solutions and AB diblock\ncopolymer / A homopolymer blends has been done and it is shown that the\nspherical micelles, cylindrical micelles and spherical vesicles are formed. It\nis also shown that the phase diagram for AB diblock copolymer / A homopolymer\nblends qualitatively agrees with the phase diagram obtained by the experiment."
    },
    {
        "anchor": "Self-assembly of coated microdroplets at the sudden expansion of a\n  microchannel: We report observations of the self-assembly of coated droplets into regular\nclusters at the sudden expansion of a microfluidic channel. A double emulsion\nconsisting of a regular train of coated microdroplets was created upstream of\nthe channel expansion, so that the inter-drop distance, droplet length,\nvelocity and coating thickness could be varied by imposing different inlet\npressures, albeit not independently. Provided that the enlarged channel remains\nsufficiently confined to prohibit propagation in double file, droplets can\nassemble sequentially into regular linear clusters at the expansion. Droplets\njoin a cluster via the coalescence of their coating film with that of the group\nahead. This coalescence occurs when the droplets approach each other to within\na critical distance at the expansion, enabled by hydrodynamic interactions\nwithin the train. Clusters comprising a finite number of droplets are obtained\nbecause reconfiguration of the droplet assembly during coalescence increases\nthe distance to the following droplet. Decreasing the inter-drop distance\nincreases the cluster size up to a maximum value beyond which continuous\nclusters form. Formalising these observations in a simple model reveals that\nclusters of any size are possible but that they occur for increasingly narrow\nranges of parameter values. Our experimental observations suggests that\nbackground experimental fluctuations limit the maximum discrete cluster size in\npractice. This method of self-assembly offers a robust alternative to flow\nfocusing for encapsulating multiple cores in a single coating film and the\npotential to build more complex colloidal building blocks by de-confining the\nclusters.",
        "positive": "Bifurcations of inflating balloons and interacting hysterons: While many materials exhibit a complex, hysteretic response to external\ndriving, there has been a surge of interest in how the complex dynamics of\ninternal materials states can be understood and designed to process and store\ninformation. We consider a system of connected rubber balloons that can be\ndescribed by a Preisach model of non-interacting hysterons under pressure\ncontrol, but for which the hysterons become coupled under volume control. We\nstudy this system by exploring the possible transition graphs, as well as by\nintroducing a configuration space approach which tracks the volumes of each\nballoon. Changes in the transition graphs turn out to be related to changes in\nthe topology of the configuration space of the balloons, providing a\nparticularly geometric view of how transition graphs can be designed, as well\nas additional information on the existence of hidden metastable states. This\nclass of systems is more general than just balloons."
    },
    {
        "anchor": "Nonlocal statistical field theory of dipolar particles in electrolyte\n  solutions: We present a nonlocal statistical field theory of a dilute electrolyte\nsolution with small additive of dipolar particles. We postulate that every\ndipolar particle is associated with an arbitrary probability distribution\nfunction (PDF) of distance between its charge centers. Using the standard\nHubbard-Stratonovich transformation, we represent the configuration integral of\nthe system in the functional integral form. We show that in the limit of a\nsmall permanent dipole moment, the functional in integrand exponent takes the\nwell known form of the Poisson-Boltzmann-Langevin (PBL) functional. In the\nmean-field approximation we obtain a non-linear integro-differential equation\nwith respect to the mean-field electrostatic potential, generalizing the PBL\nequation for the point-like dipoles obtained first by Abrashkin et al. We apply\nthe obtained equation in its linearized form to derivation of the expressions\nfor the mean-field electrostatic potential of the point-like test ion and its\nsolvation free energy in salt-free solution, as well as in solution with salt\nions. For the 'Yukawa'-type PDF we obtain analytic relations for both the\nelectrostatic potential and the solvation free energy of the point-like test\nion. We obtain a general expression for the bulk electrostatic free energy of\nthe solution within the random phase approximation (RPA). For the salt-free\nsolution of the dipolar particles for the Yukawa-type PDF we obtain an analytic\nrelation for the electrostatic free energy.",
        "positive": "Phase diagram of a model for a binary mixture of nematic molecules on a\n  Bethe lattice: We investigate the phase diagram of a discrete version of the Maier-Saupe\nmodel with the inclusion of additional degrees of freedom to mimic a\ndistribution of rodlike and disklike molecules. Solutions of this problem on a\nBethe lattice come from the analysis of the fixed points of a set of nonlinear\nrecursion relations. Besides the fixed points associated with isotropic and\nuniaxial nematic structures, there is also a fixed point associated with a\nbiaxial nematic structure. Due to the existence of large overlaps of the\nstability regions, we resorted to a scheme to calculate the free energy of\nthese structures deep in the interior of a large Cayley tree. Both\nthermodynamic and dynamic-stability analyses rule out the presence of a biaxial\nphase, in qualitative agreement with previous mean-field results."
    },
    {
        "anchor": "Thermodynamic properties of microbian populations on biological\n  membranes: In this work we to develop a general statistical mechanic formalism to study\nsystems restricted to surfaces of revolution, these are a very well model to\nstudy the termodinamical properties of microbiological systems and\nmacromolecules lies on biological membranes such as cellular well.",
        "positive": "Macroscopic equivalence for microscopic motion in a turbulence driven\n  three-dimensional self-assembly reactor: We built and characterised a macroscopic self-assembly reactor that agitates\nmagnetic, centimeter-sized particles with a turbulent water flow. By scaling up\nthe self-assembly processes to the centimeter-scale, the characteristic time\nconstant scale also drastically increases. This makes the system a physical\nsimulator of microscopic self-assembly, where the interaction of inserted\nparticles are easily observable. Trajectory analysis of single particles\nreveals their velocity to be a Maxwell-Boltzmann distribution and it shows that\ntheir average squared displacement over time can be modelled by a confined\nrandom walk model, demonstrating a high level of similarity to Brownian motion.\nThe interaction of two particles has been modelled and verified experimentally\nby observing the distance between two particles over time. The disturbing\nenergy (analogue to temperature) that was obtained experimentally increases\nwith sphere size, and differs by an order of magnitude between single-sphere\nand two-sphere systems (approximately 80 $\\mathrm{\\mu J}$ versus 6.5\n$\\mathrm{\\mu J}$, respectively)."
    },
    {
        "anchor": "Relative Resolution: A Computationally Efficient Implementation in\n  LAMMPS: Recently, a novel type of a multiscale simulation, called Relative Resolution\n(RelRes), was introduced. In a single system, molecules switch their resolution\nin terms of their relative separation, with near neighbors interacting via\nfine-grained potentials yet far neighbors interacting via coarse-grained\npotentials; notably, these two potentials are analytically parameterized by a\nmultipole approximation. This multiscale approach is consequently able to\ncorrectly retrieve across state space, the structural and thermal, as well as\nstatic and dynamic, behavior of various nonpolar mixtures. Our current work\nfocuses on the practical implementation of RelRes in LAMMPS, specifically for\nthe commonly used Lennard-Jones potential. By examining various correlations\nand properties of several alkane liquids, including complex solutions of\nalternate cooligomers and block copolymers, we confirm the validity of this\nautomated LAMMPS algorithm. Most importantly, we demonstrate that this RelRes\nimplementation gains almost an order of magnitude in computational efficiency,\nas compared with conventional simulations. We thus recommend this novel LAMMPS\nalgorithm for anyone studying systems governed by Lennard-Jones interactions.",
        "positive": "Electrostatics in a crooked nanochannel in a newly developed curvilinear\n  coordinate system: Both biological and artificial nanochannels in crooked shape exhibit unusual\ntransportational characteristics, bringing about a challenge to the traditional\ntheoretical analysis of nanofluidics, partly due to their complicated boundary\ndescription. In this paper, by developing a curvilinear coordinate system for\ncrooked nanochannels, we successfully solve the electrostatic Poisson-Boltzmann\nequation analytically for a two-dimensional nanochannel, with its effectiveness\nconfirmed through numerical calculation. The influences of the geometric\nprofile of the nanochannel on the distribution of electric potential, ionic\nconcentration, and surface charge on channel walls can be quantitatively\nevaluated in a facilitated way in terms of these curvilinear coordinates. Such\na technique can be widely applied to many nanofluidic systems."
    },
    {
        "anchor": "Near-critical spreading of droplets: We study the spreading of droplets in a near-critical phase-separated liquid\nmixture, using a combination of experiments, lubrication theory and\nfinite-element numerical simulations. The classical Tanner's law describing the\nspreading of viscous droplets is robustly verified when the critical\ntemperature is neared. Furthermore, the microscopic cut-off length scale\nemerging in this law is obtained as a single free parameter for each given\ntemperature. In total-wetting conditions, this length is interpreted as the\nthickness of the thin precursor film present ahead of the apparent contact\nline. The collapse of the different evolutions onto a single Tanner-like master\ncurve demonstrates the universality of viscous spreading before entering in the\nfluctuation-dominated regime. Finally, our results reveal a counter-intuitive\nand sharp thinning of the precursor film when approaching the critical\ntemperature, which is attributed to the vanishing spreading parameter at the\ncritical point.",
        "positive": "A classical nucleation theory description of active colloid assembly: Non-aligning self-propelled particles with purely repulsive excluded volume\ninteractions undergo athermal motility-induced phase separation into a dilute\ngas and a dense cluster phase. Here, we use enhanced sampling computational\nmethods and analytic theory to examine the kinetics of formation of the dense\nphase. Despite the intrinsically nonequilibrium nature of the phase transition,\nwe show that the kinetics can be described using an approach analogous to\nequilibrium classical nucleation theory, governed by an effective free energy\nof cluster formation with identifiable bulk and surface terms. The theory\ncaptures the location of the binodal, nucleation rates as a function of\nsupersaturation, and the cluster size distributions below the binodal, while\ndiscrepancies in the metastable region reveal additional physics about the\nearly stages of active crystal formation. The success of the theory shows that\na framework similar to equilibrium thermodynamics can be obtained directly from\nthe microdynamics of an active system, and can be used to describe the kinetics\nof evolution toward nonequilibrium steady states."
    },
    {
        "anchor": "Multiscale Modeling of Coarse-Grained Macromolecular Liquids: A first-principle multiscale modeling approach is presented, which is derived\nfrom the solution of the Ornstein-Zernike equation for the coarse-grained\nrepresentation of polymer liquids. The approach is analytical, and for this\nreason is transferable. It is here applied to determine the structure of\nseveral polymeric systems, which have different parameter values, such as\nmolecular length, monomeric structure, local flexibility, and thermodynamic\nconditions. When the pair distribution function obtained from this procedure is\ncompared with the results from a full atomistic simulation, it shows\nquantitative agreement. Moreover, the multiscale procedure accurately captures\nboth large and local scale properties while remaining computationally\nadvantageous.",
        "positive": "A Numerical Model for Brownian Particles Fluctuating in Incompressible\n  Fluids: We present a numerical method that consistently implements thermal\nfluctuations and hydrodynamic interactions to the motion of Brownian particles\ndispersed in incompressible host fluids. In this method, the thermal\nfluctuations are introduced as random forces acting on the Brownian particles.\nThe hydrodynamic interactions are introduced by directly resolving the fluid\nmotions with the particle motion as a boundary condition to be satisfied. The\nvalidity of the method has been examined carefully by comparing the present\nnumerical results with the fluctuation-dissipation theorem whose analytical\nform is known for dispersions of a single spherical particle. Simulations are\nthen performed for more complicated systems, such as a dispersion composed of\nmany spherical particles and a single polymeric chain in a solvent."
    },
    {
        "anchor": "Steady-State Cracks in Viscoelastic Lattice Models: We study the steady-state motion of mode III cracks propagating on a lattice\nexhibiting viscoelastic dynamics. The introduction of a Kelvin viscosity $\\eta$\nallows for a direct comparison between lattice results and continuum\ntreatments. Utilizing both numerical and analytical (Wiener-Hopf) techniques,\nwe explore this comparison as a function of the driving displacement $\\Delta$\nand the number of transverse sites $N$. At any $N$, the continuum theory misses\nthe lattice-trapping phenomenon; this is well-known, but the introduction of\n$\\eta$ introduces some new twists. More importantly, for large $N$ even at\nlarge $\\Delta$, the standard two-dimensional elastodynamics approach completely\nmisses the $\\eta$-dependent velocity selection, as this selection disappears\ncompletely in the leading order naive continuum limit of the lattice problem.",
        "positive": "Clustering-induced velocity-reversals of active colloids mixed with\n  passive particles: Recent experiments have shown that colloidal suspensions can spontaneously\nself-assemble into dense clusters of various internal structures, sizes and\ndynamical properties when doped with active Janus particles.\nCharacteristically, these clusters move ballistically during their formation,\nbut dynamically revert their velocity and temporarily move opposite to the\nself-propulsion direction of the Janus particles they contain. Here we explore\na simple effective model of colloidal mixtures which allows reproducing most\naspects seen in experiments, including the morphology and the velocity-reversal\nof the clusters. We attribute the latter to the nonreciprocal phoretic\nattractions of the passive particles to the active colloids' caps, taking place\neven at close contact and pushing the active particles backwards. When the\nphoretic interactions are repulsive, in turn, they cause dynamical aggregation\nof passive colloids in the chemical density minima produced by the active\nparticles, as recently seen in experiments; in other parameter regimes they\ninduce travelling fronts of active particles pursued by passive ones coexisting\nwith an active gas."
    },
    {
        "anchor": "Extracting bulk properties of self-assembling systems from small\n  simulations: For systems that self assemble into finite-sized objects, it is sometimes\nconvenient to compute the thermodynamics for a small system where a single\nassembly can form. However, we show that in the canonical ensemble the use of\nsmall systems can lead to significant finite-size effects due to the\nsuppression of concentration fluctuations. We introduce methods to estimate the\nbulk-yields from simulations of small systems and to follow the convergence of\nyields with system size, under the assumptions that the various species behave\nideally. We also propose an extension to the umbrella sampling technique that\nallows the formation of multiple finite-sized objects.",
        "positive": "Mesoscale Simulation Approach for Assembly of Small Deformable Objects: We adapt Vertex models to understand the physical origin of the formation of\nlong-range ordered structures in repulsive soft particles. The model\nincorporates contributions from the volume and surface area of each particle.\nSampling using Monte Carlo simulations allows the system to naturally select\npreferred structures. We observe transitions between a body-centered cubic\nordered state and a disordered state. Constraints to the simulation domain can\nsuppress or allow the system to follow a path similar to Martensitic\ntransformations from one ordered state to another ordered state. Finally, we\nshow that rapid quenches from a disordered state into the ordered region lead\nto metastable local particle arrangements instead of a large-scale single\ncrystal."
    },
    {
        "anchor": "Dragging a polymer in a viscous fluid: steady-state and transient: We study the conformation and dynamics of a single polymer chain that is\npulled by a constant force applied at its one end with the other end free. Such\na situation is relevant to the growing technology of manipulating individual\nmacromolecules, which offers a paradigm research for probing\nfar-from-equilibrium responses of long flexible biological polymers. We first\nanalyze the Rouse model for the Gaussian chains for which the exact analytical\nresults can be obtained. More realistic features such as the finite\nextensibility, the excluded volume and the hydrodynamic interactions are taken\ninto account with the help of the scaling argument, which leads to various\nnontrivial predictions such as the stretching-force-dependent friction\nconstants. We elucidate (i) generalized dynamical equations of state describing\nextension/friction laws in steady-state and (ii) the tension propagation laws\nin the transient process. We point out that the time evolutions of the dynamic\nfriction in the transient process crucially depend on the experimental\nprotocol, i.e., either constant force or velocity ensemble, which might be\ndetectable in experiments using giant DNAs and chromosomes.",
        "positive": "Repulsion-attraction switching of nematic colloids formed by liquid\n  crystal dispersions of polygonal prisms: Self-assembly of colloidal particles due to elastic interactions in nematic\nliquid crystals promises tunable composite materials and can be guided by\nexploiting surface functionalization, geometric shape and topology, though\nthese means of controlling self-assembly remain limited. Here, we realize\nlow-symmetry achiral and chiral elastic colloids in the nematic liquid crystals\nusing colloidal polygonal concave and convex prisms. We show that the\ncontrolled pinning of disclinations at the prisms edges alters the symmetry of\ndirector distortions around the prisms and their orientation with respect to\nthe far-field director. The controlled localization of the disclinations at the\nprism's edges significantly influences anisotropy of the diffusion properties\nof prisms dispersed in liquid crystals and allows one to modify their\nself-assembly. We show that elastic interactions between polygonal prisms can\nbe switched between repulsive and attractive just by controlled re-pinning the\ndisclinations at different edges using laser tweezers. Our findings demonstrate\nthat elastic interactions between colloidal particles dispersed in nematic\nliquid crystals are sensitive to the topologically equivalent but geometrically\nrich controlled configurations of the particle-induced defects."
    },
    {
        "anchor": "Fertile metastability: We deal here with three metastable systems: 1{\\textdegree}- the dowser\ntexture, 2{\\textdegree}- supertwistedcholesterics and 3{\\textdegree}-\nhypotwisted cholesterics. We outline remarkable properties of tropisms of the\ndowser texture stemming from its low symmetry and we show that, using setups\ncalled Dowsons Colliders, nematic monopoles can be nucleated, set into motion\nand brought into collisions in the dowser texture. Subsequently we point out\nthat nucleation of dislocation loops occurs in cholesteric layers compressed or\ndilated between cylindrical mica sheets. Under compression, three modes of\nnucleation of dislocation loops have been identified: individual, serial and\ncontinuous. The serial mode generates dislocation nets made of L circular loops\nconnected by C radial crossing into superloops. Similar superloops can also be\ngenerated under dilation. We analyse the topology of superloops in terms of the\ntheory of knots and point out they can be reduced into the unknot by\nReidemeister moves. In other words, superloops are multiply folded loops that\ncan be continuously unfolded.",
        "positive": "Buckling of self-assembled colloidal structures: Although buckling is a prime route to achieve functionalization and synthesis\nof single colloids, buckling of colloidal structures---made up of multiple\ncolloids---remains poorly studied. Here, we investigate the buckling of the\nsimplest form of a colloidal structure, a colloidal chain that is\nself-assembled through critical Casimir forces. We demonstrate that the\nmechanical instability of such a chain is strikingly reminiscent of that of\nclassical Euler buckling but with thermal fluctuations and plastic effects\nplaying a significant role. Namely, we find that fluctuations tend to diverge\nclose to the onset of buckling and that plasticity controls the buckling\ndynamics at large deformations. Our work provides insight into the effect of\ngeometrical, thermal and plastic interactions on the nonlinear mechanics of\nself-assembled structures, of relevance for the rheology of complex and living\nmatter and the rational design of colloidal architectures."
    },
    {
        "anchor": "Non-linear mechanical response of the Red Blood Cell: We measure the dynamical mechanical properties of human red blood cells.\nSingle cell response is measured with optical tweezers. We investigate both the\nstress relaxation following a fast deformation, and the effect of varying the\nstrain rate. We find a power law decay of the stress as a function of time,\ndown to a plateau stress, and a power law increase of the cell's elasticity as\na function of the strain rate. Interestingly, the exponents of these quantities\nviolate the linear superposition principle, indicating a nonlinear response. We\npropose that this is due to breaking of a fraction of the crosslinks during the\ndeformation process. The Soft Glassy Rheology Model accounts for the relation\nbetween the exponents we observe experimentally. This picture is consistent\nwith recent models of bond remodeling in the red blood cell's molecular\nstructure. Our results imply that the blood cell's mechanical behavior depends\ncritically on the deformation process.",
        "positive": "Dynamics of Ordered Active Columns: Flows, Twists, and Waves: We formulate the hydrodynamics of active columnar phases, with\ntwo-dimensional translational order in the plane perpendicular to the columns\nand no elastic restoring force for relative sliding of the columns, using the\ngeneral formalism of an active model H$^*$. Our predictions include:\ntwo-dimensional odd elasticity coming from three-dimensional plasmon-like\noscillations of the columns in chiral polar phases with a frequency that is\nindependent of wavenumber and non-analytic; a buckling instability coming from\nthe generic force-dipole active stress analogous to the mechanical\nHelfrich-Hurault instability in passive materials; the selection of helical\ncolumn undulations by apolar chiral activity."
    },
    {
        "anchor": "Effect of time and thermo-mechanical couplings on polymers: Analysis of the thermo-mechanical behaviour of polymers has been and still is\nthe subject of many rheological studies both experimentally and theoretically.\nFor small deformations, the modelling framework retained by rheologists is\noften of linear visco-elasticity, which led to the definition of complex\nmodules and used to identify the glass transition temperature as the so called\nrule of time-temperature superposition. In this context, the effects of time\nare almost unanimously associated with viscous effects. It has also been\nobserved that the dissipative effects associated with viscous effects are often\nvery small compared to the coupling of sources indicating a high sensitivity of\npolymeric materials to temperature variations. This work is mainly focused on\nestablishing the exact role of coupling effects, which also induce the effect\nof time. Using traditional experimental methods of visco-analysis (DMTA) and\nvia an energy analysis of the behaviour, the goal of the thesis is to try to\nrestate the time-temperature equivalence rule under the Thermodynamics of\nIrreversible Processes, taking into account the dissipative effects and\ncoupling induced process deformation.",
        "positive": "Partition sum of thermal, under-constrained systems: Athermal (i.e. zero-temperature) under-constrained systems are typically\nfloppy, but they can be rigidified by the application of external strain.\nFollowing our recently developed analytical theory for the athermal limit, here\nand in the companion paper, we extend this theory to under-constrained systems\nat finite temperatures. Close to the athermal transition point, we derive from\nfirst principles the partition sum for a broad class of under-constrained\nsystems, from which we obtain analytic expressions for elastic material\nproperties such as isotropic tension $t$ and shear modulus $G$ in terms of\nisotropic strain $\\varepsilon$, shear strain $\\gamma$, and temperature $T$. Our\nwork unifies the physics of systems as diverse as polymer fibers & networks,\nmembranes, and vertex models for biological tissues."
    },
    {
        "anchor": "On the structure of blue phase III: We report large scale simulations of the blue phases of cholesteric liquid\ncrystals. Our results suggest a structure for blue phase III, the blue fog,\nwhich has been the subject of a long debate in liquid crystal physics. We\npropose that blue phase III is an amorphous network of disclination lines,\nwhich is thermodynamically and kinetically stabilised over crystalline blue\nphases at intermediate chiralities}. This amorphous network becomes ordered\nunder an applied electric field, as seen in experiments.",
        "positive": "Detergency and its implications for oil emulsion sieving and separation: Separating petroleum hydrocarbons from water is an important problem to\naddress in order to mitigate the disastrous effects of hydrocarbons on aquatic\necosystems. A rational approach to address the problem of marine oil water\nseparation is to disperse the oil with the aid of surfactants in order to\nminimize the formation of large slicks at the water surface and to maximize the\noil-water interfacial area. Here we investigate the fundamental wetting and\ntransport behavior of such surfactant-stabilized droplets and the flow\nconditions necessary to perform sieving and separation of these stabilized\nemulsions. We show that, for water soluble surfactants, such droplets are\ncompletely repelled by a range of materials (intrinsically underwater\nsuperoleophobic) due to the detergency effect; therefore, there is no need for\nsurface micro/nanotexturing or chemical treatment to repel the oil and prevent\nfouling of the filter. We then simulate and experimentally investigate the\neffect of emulsion flow rate on the transport and impact behavior of such\ndroplets on rigid meshes to identify the minimum pore opening (w) necessary to\nfilter a droplet with a given diameter (d) in order to minimize the pressure\ndrop across the mesh and therefore maximize the filtering efficiency, which is\nstrongly dependent on w. We define a range of flow conditions and droplet sizes\nwhere minimum droplet deformation is to be expected and therefore find that the\ncondition of is sufficient for efficient separation. With this new\nunderstanding, we demonstrate the use of a commercially available\nfilter--without any additional surface engineering or functionalization--to\nseparate oil droplets from a surfactant stabilized emulsion with a flux of\n11,000 L m$^{-2}$ hr$^{-1}$ bar$^{-1}$. We believe these findings can inform\nthe design of future oil separation materials."
    },
    {
        "anchor": "Unfolding of a diblock chain and its anomalous diffusion induced by\n  active particles: We study the structural and dynamical behaviors of a diblock copolymer chain\nin a bath of active Brownian particles (ABPs) by extensive Brownian dynamics\nsimulation in a two-dimensional model system. Specifically, the A block of\nchain is self-attractive, while the B block is self-repulsive. We find, beyond\na threshold, the A block unfolds with a pattern like extracting a woolen string\nfrom a ball. The critical force decreases with the increase of the B block\nlength,NB, for short cases, then keeps a constant with further increase of NB.\nIn addition, we find a power law exists between the unfolding time of chain and\nactive force, Fa, as well as NB. Finally, we focus on the translational and\nrotational diffusion of chain, and find that both of them remain\nsupper-diffusive at the long time limit for small active forces due to an\nasymmetry distribution of ABPs. Our results open new routes for manipulating\npolymer's behaviors with ABPs.",
        "positive": "The Cone Phase of Liquid Crystals: Triangular Lattice of Double-Tilt\n  Cylinders: We predict the existence of a new defect-lattice phase near the nematic -\nsmectic-C (NC) transition. This tilt- analogue of the blue phase is a lattice\nof double-tilt cylinders. We discuss the structure and stability of the cone\nphase. We suggest that many `nematics' exhibiting short range layering and tilt\norder may in fact be in the molten cone phase, which is a line liquid."
    },
    {
        "anchor": "Neutron Small Angle Scattering on Liquid Helium in the temperature Range\n  1.5-4.2 K: The small angle neutron scattering from liquid helium at saturated vapour\npressure in the temperature range from 1.5 to 4.2 K was measured with the\ninstrument D22 of the ILL Grenoble at a wavelength of 4.6 angstrom. The zero\nangle cross section is monotonically decreasing with decreasing temperature and\ndoes not show any singularity at the lambda-point. On the other handd, we\nobserve a change of the slope of the temperature dependence of thw second\nmomentum of the pair correlation function at the lambda-point that reflects the\ntransition of liquid to the superfluid state.",
        "positive": "Residual stress in athermal soft disordered solids: insights from\n  microscopic and mesoscale models: In soft amorphous materials, shear cessation after large shear deformation\nleads to structures having residual shear stress. The origin of these states\nand the distribution of the local shear stresses within the material is not\nwell understood, despite its importance for the change in material properties\nand consequent applications. In this work, we use molecular dynamics\nsimulations of a model dense non-Brownian soft amorphous material to probe the\nnon-trivial relaxation process towards a residual stress state. We find that,\nsimilar to thermal glasses, an increase in shear rate prior to the shear\ncessation leads to lower residual stress states. We rationalise our findings\nusing a mesoscopic elasto-plastic description that explicitly includes a long\nrange elastic response to local shear transformations. We find that after flow\ncessation the initial stress relaxation indeed depends on the pre-sheared\nstress state, but the final residual stress is majorly determined by newly\nactivated plastic events occurring during the relaxation process. Our\nsimplified coarse grained description not only allows to capture the\nphenomenology of residual stress states but also to rationalise the altered\nmaterial properties that are probed using small and large deformation protocols\napplied to the relaxed material."
    },
    {
        "anchor": "Anomalous dimensions of the Smoluchowski coagulation equation: The coagulation (or aggregation) equation was introduced by Smoluchowski in\n1916 to describe the clumping together of colloidal particles through\ndiffusion, but has been used in many different contexts as diverse as physical\nchemistry, chemical engineering, atmospheric physics, planetary science, and\neconomics. The effectiveness of clumping is described by a kernel $K(x,y)$,\nwhich depends on the sizes of the colliding particles $x,y$. We consider\nkernels $K = (xy)^{\\gamma}$, but any homogeneous function can be treated using\nour methods. For sufficiently effective clumping $1 \\ge \\gamma > 1/2$, the\ncoagulation equation produces an infinitely large cluster in finite time (a\nprocess known as the gel transition). Using a combination of analytical methods\nand numerics, we calculate the anomalous scaling dimensions of the main cluster\ngrowth, calling into question results much used in the literature. Apart from\nthe solution branch which originates from the exactly solvable case $\\gamma =\n1$, we find a new branch of solutions near $\\gamma = 1/2$, which violates\nscaling relations widely believed to hold universal.",
        "positive": "Dielectric relaxation of thin films of polyamide random copolymers: We investigate the relaxation behavior of thin films of a polyamide random\ncopolymer, PA66/6I, with various film thicknesses using dielectric relaxation\nspectroscopy. Two dielectric signals are observed at high temperatures, the\n$\\alpha$-process and the relaxation process due to electrode polarization (the\nEP-process). The relaxation time of the EP-process has a Vogel-Fulcher-Tammann\ntype of temperature dependence, and the glass transition temperature, $T_{\\rm\ng}$, evaluated from the EP-process agrees very well with the $T_{\\rm g}$\ndetermined from the thermal measurements. The fragility index derived from the\nEP-process increases with decreasing film thickness. The relaxation time and\nthe dielectric relaxation strength of the EP-process are described by a linear\nfunction of the film thickness $d$ for large values of $d$, which can be\nregarded as experimental evidence for the validity of attributing the observed\nsignal to the EP-process. Furthermore, there is distinct deviation from this\nlinear law for thicknesses smaller than a critical value. This deviation\nobserved in thinner films is associated with an increase in the mobility and/or\ndiffusion constant of the charge carriers responsible for the EP-process. The\n$\\alpha$-process is located in a high frequency region than the EP-process at\nhigh temperatures, but merges with the EP-process at lower temperatures near\nthe glass transition region. The thickness dependence of the relaxation time of\nthe $\\alpha$-process is different from that of the EP-process. This suggests\nthat there is decoupling between the segmental motion of the polymers and the\ntranslational motion of the charge carriers in confinement."
    },
    {
        "anchor": "Stark Effect of Hybrid Charge Transfer States at Planar ZnO/Organic\n  Interfaces: We investigate the bias-dependence of the hybrid charge transfer state\nemission at planar heterojunctions between the metal oxide acceptor ZnO and\nthree donor molecules. The electroluminescence peak energy linearly increases\nwith the applied bias, saturating at high fields. Variation of the organic\nlayer thickness and deliberate change of the ZnO conductivity through\ncontrolled photo-doping allow us to confirm that this bias-induced spectral\nshifts relate to the internal electric field in the organic layer rather than\nthe filling of states at the hybrid interface. We show that existing continuum\nmodels overestimate the hole delocalization and propose a simple electrostatic\nmodel in which the linear and quadratic Stark effects are explained by the\nelectrostatic interaction of a strongly polarizable molecular cation with its\nmirror image.",
        "positive": "Border-Crossing Model for the Diffusive Coarsening of Two-Dimensional\n  and Quasi-Two-Dimensional Wet Foams: For dry foams, the transport of gas from small high-pressure bubbles to large\nlow-pressure bubbles is dominated by diffusion across the thin soap films\nseparating neighboring bubbles. For wetter foams, the film areas become smaller\nas the Plateau borders and vertices inflate with liquid. So-called\n\"border-blocking\" models can explain some features of wet-foam coarsening based\non the presumption that the inflated borders totally block the gas flux,\nhowever, this approximation dramatically fails in the wet/unjamming limit where\nthe bubbles become close-packed spheres and coarsening proceeds even though\nthere are no films. Here, we account for the ever-present border-crossing flux\nby a new length scale defined by the average gradient of gas concentration\ninside the borders. We compute that it is proportional to the geometric average\nof film and border thicknesses, and we verify this scaling by numerical\nsolution of the diffusion equation. We similarly consider transport across\ninflated vertices and surface Plateau borders in quasi-2d foams. And we show\nhow the $dA/dt=K_0(n-6)$ von~Neumann law is modified by the appearance of terms\nthat depend on bubble size and shape as well as the concentration gradient\nlength scales. Finally, we use the modified von~Neumann law to compute the\ngrowth rate of the average bubble area, which is not constant."
    },
    {
        "anchor": "Self-assembly of 2D membranes from mixtures of hard rods and depleting\n  polymers: We elucidate the molecular forces leading to assembly of two dimensional\nmembrane-like structures composed of a one rod-length thick monolayer of\naligned rods from an immiscible suspension of hard rods and depleting polymers.\nWe perform simulations which predict that monolayer membranes are\nthermodynamically stable above a critical rod aspect ratio and below a critical\ndepletion interaction length scale. Outside of these conditions alternative\nstructures such as stacked smectic columns or nematic droplets are\nthermodynamically stable. These predictions are confirmed using an experimental\nmodel system of virus rod-like molecules and non-adsorbing polymer. Our work\ndemonstrates that collective molecular protrusion fluctuations alone are\nsufficient to stabilize membranes composed of homogenous rods with simple\nexcluded volume interactions.",
        "positive": "Brittle fracture in a periodic structure with internal potential energy.\n  Spontaneous crack propagation: Spontaneous brittle fracture is studied based on the recently introduced\nmodel (Mishuris and Slepyan, Brittle fracture in a periodic structure with\ninternal potential energy. Proc. Roy. Soc. A, in press). A periodic structure\nis considered, where only the prospective crack-path layer is specified as a\ndiscrete set of alternating initially stretched and compressed bonds. A bridged\ncrack destroying initially stretched bonds may propagate under a certain level\nof the internal energy without external sources. The general analytical\nsolution with the crack speed $-$ energy relation is presented in terms of the\ncrack-related dynamic Green's function. For the anisotropic two-line chain and\nlattice considered earlier in quasi-statics, the dynamic problem is examined in\ndetail. The crack speed is found to grow unboundedly as the energy approaches\nits upper limit. It is revealed that the spontaneous fracture can occur in the\nform of a pure bridged, partially bridged or fully open crack depending on the\ninternal energy level. Generally, the steady-state mode of the crack\npropagation is found to be realised, whereas an irregular growth, clustering\nand the crack speed oscillations are detected in a vicinity of the lower bound\nof the energy."
    },
    {
        "anchor": "Lassoing saddle splay and the geometrical control of topological defects: Systems with holes, such as colloidal handlebodies and toroidal droplets,\nhave been studied in the nematic liquid crystal (NLC) 4-cyano-4'-pentylbiphenyl\n(5CB): both point and ring topological defects can occur within each hole and\naround the system, while conserving the system's overall topological charge.\nHowever, what has not been fully appreciated is the ability to manipulate the\nhole geometry with homeotropic (perpendicular) anchoring conditions to induce\ncomplex, saddle-like deformations. We exploit this by creating an array of\nholes suspended in an NLC cell with oriented planar (parallel) anchoring at the\ncell boundaries. We study both 5CB and a binary mixture of bicyclohexane\nderivatives (CCN-47 and CCN-55). Through simulations and experiments, we study\nhow the bulk saddle deformations of each hole interact to create novel defect\nstructures, including an array of disclination lines, reminiscent of those\nfound in liquid crystal blue phases. The line locations are tunable via the NLC\nelastic constants, the cell geometry, and the size and spacing of holes in the\narray. This research lays the groundwork for the control of complex elastic\ndeformations of varying length scales via geometrical cues in materials that\nare renowned in the display industry for their stability and easy\nmanipulability.",
        "positive": "On the origin and structure of liquid crystalline Blue Phase III: The origin and structure of self assembled chiral liquid crystalline Blue\nPhase III (BPIII) have remained an enigma despite efforts spreading over\ndecades. We report here an off-lattice NVT molecular dynamics simulation study\nof a system of polar chiral ellipsoidal molecules, which spontaneously exhibits\nBPIII , considering coarse-grained attractive-repulsive pair interaction\nappropriate for anisotropic liquid crystal mesogens. We have observed that\nsuitable selection of chiral and dipolar strengths not only gives rise to\nthermodynamically stable BPIII but novel Smectic and Bilayered BPIII as well.\nFurther, we have demonstrated that occurence of BPIII and its layered\ncounterparts depend crucially on molecular elongation."
    },
    {
        "anchor": "Low force unfolding of a single-domain protein by parallel pathways: Deviations from linearity in the dependence of the logarithm of protein\nunfolding rates, $\\log k_u(f)$, as a function of mechanical force, $f$,\nmeasurable in single molecule experiments, can arise for many reasons. In\nparticular, upward curvature in $\\log k_u(f)$ as a function of $f$ implies that\nthe underlying energy landscape must be multidimensional with the possibility\nthat unfolding ensues by parallel pathways. Here, simulations using the SOP-SC\nmodel of a wild type $\\beta$-sandwich protein and several mutants, with\nimmunoglobulin folds, show upward curvature in the unfolding kinetics. There\nare substantial changes in the structures of the transition state ensembles as\nforce is increased, signaling a switch in the unfolding pathways. Our results,\nwhen combined with previous theoretical and experimental studies, show that\nparallel unfolding of structurally unrelated single domain proteins can be\ndetermined from the dependence of $\\log k_u(f)$ as a function of force (or\n$\\log k_u[C]$ where $[C]$ is the denaturant concentration).",
        "positive": "Unexpected relaxation dynamics of a self-avoiding polymer in cylindrical\n  confinement: We report extensive simulations of the relaxation dynamics of a self-avoiding\npolymer confined inside a cylindrical pore. In particular, we concentrate on\nexamining how confinement influences the scaling behavior of the global\nrelaxation time of the chain, t, with the chain length N and pore diameter D.\nAn earlier scaling analysis based on the de Gennes blob picture led to t ~\nN^2D^(1/3). Our numerical effort that combines molecular dynamics and Monte\nCarlo simulations, however, consistently produces different t-results for N up\nto 2000. We argue that the previous scaling prediction is only asymptotically\nvalid in the limit N >> D^(5/3) >> 1, which is currently inaccessible to\ncomputer simulations and, more interestingly, is also difficult to reach in\nexperiments. Our results are thus relevant for the interpretation of recent\nexperiments with DNA in nano- and micro-channels."
    },
    {
        "anchor": "Continuum modeling of size-segregation and flow in dense, bidisperse\n  granular media: Accounting for segregation driven by both pressure gradients\n  and shear-strain-rate gradients: Dense mixtures of particles of varying size tend to segregate based on size\nduring flow. Granular size-segregation plays an important role in many\nindustrial and geophysical processes, but the development of coupled, continuum\nmodels capable of predicting the evolution of segregation dynamics and flow\nfields in dense granular media across different geometries has remained a\nlongstanding challenge. One reason is because size-segregation stems from two\ndriving forces: (1) pressure gradients and (2) shear-strain-rate gradients.\nAnother reason is due to the challenge of integrating segregation models with\nrheological constitutive equations for dense granular flow. In this paper, we\nbuild upon our prior work, which combined a model for\nshear-strain-rate-gradient-driven segregation with a nonlocal continuum model\nfor dense granular flow rheology, and append a model for\npressure-gradient-driven segregation. We perform discrete element method (DEM)\nsimulations of dense flow of bidisperse granular systems in two flow\ngeometries, in which both segregation driving forces are present: namely,\ninclined plane flow and planar shear flow with gravity. Steady-state DEM data\nfrom inclined plane flow is used to determine the dimensionless material\nparameters in the pressure-gradient-driven segregation model for both spheres\nand disks. Then, predictions of the coupled, continuum model accounting for\nboth driving forces are tested against DEM simulation results across different\ncases of both inclined plane flow and planar shear flow with gravity, while\nvarying parameters such as the size of the flow geometry, the driving\nconditions of flow, and the initial conditions. Overall, we find that it is\ncrucial to account for both driving forces to capture segregation dynamics in\ndense, bidisperse granular media across both flow geometries with a single set\nof parameters.",
        "positive": "Dynamic Arrest in Polymer Melts: Competition between Packing and\n  Intramolecular Barriers: We present molecular dynamics simulations of a simple model for polymer melts\nwith intramolecular barriers. We investigate structural relaxation as a\nfunction of the barrier strength. Dynamic correlators can be consistently\nanalyzed within the framework of the Mode Coupling Theory (MCT) of the glass\ntransition. Control parameters are tuned in order to induce a competition\nbetween general packing effects and polymer-specific intramolecular barriers as\nmechanisms for dynamic arrest. This competition yields unusually large values\nof the so-called MCT exponent parameter and rationalize qualitatively different\nobservations for simple bead-spring and realistic polymers. The systematic\nstudy of the effect of intramolecular barriers presented here also establishes\na fundamental difference between the nature of the glass transition in polymers\nand in simple glass-formers."
    },
    {
        "anchor": "Structure and kinetics in the freezing of nearly hard spheres: We consider homogeneous crystallisation rates in confocal microscopy\nexperiments on colloidal nearly hard spheres at the single particle level.\nThese we compare with Brownian dynamics simuations by carefully modelling the\nsoftness in the interactions with a Yukawa potential, which takes account of\nthe electrostatic charges present in the experimental system. Both structure\nand dynamics of the colloidal fluid are very well matched between experiment\nand simulation, so we have confidence that the system simulated is close to\nthat in the experiment. In the regimes we can access, we find reasonable\nagreement in crystallisation rates between experiment and simulations, noting\nthat the larger system size in experiments enables the formation of critical\nnuclei and hence crystallisation at lower supersaturations than the\nsimulations. We further examine the structure of the metastable fluid with a\nnovel structural analysis, the topological cluster classification. We find that\nat densities where the hard sphere fluid becomes metastable, the dominant\nstructure is a cluster of m=10 particles with five-fold symmetry. At a particle\nlevel, we find three regimes for the crystallisation process: metastable fluid\n(dominated by m=10 clusters), crystal and a transition region of frequent\nhopping between crystal-like environments and other (m\\neq10) structures",
        "positive": "Dynamics of two-dimensional liquid bridges: We have simulated the motion of a single vertical, two-dimensional liquid\nbridge spanning the gap between two flat, horizontal solid substrates of given\nwettabilities, using a multicomponent pseudopotential lattice Boltzmann method.\nFor this simple geometry, the Young-Laplace equation can be solved\n(quasi-)analytically to yield the equilibrium bridge shape under gravity, which\nprovides a check on the validity of the numerical method. In steady-state\nconditions, we calculate the drag force exerted by the moving bridge on the\nconfining substrates as a function of its velocity, for different contact\nangles and Bond numbers. We also study how the bridge deforms as it moves, as\nparametrized by the changes in the advancing and receding contact angles at the\nsubstrates relative to their equilibrium values. Finally, starting from a\nbridge within the range of contact angles and Bond numbers in which it can\nexist at equilibrium, we investigate how fast it must move in order to break\nup."
    },
    {
        "anchor": "Cluster and reentrant anomalies of nearly Gaussian core particles: We study through integral equation theory and numerical simulations the\nstructure and dynamics of fluids composed of ultrasoft, nearly Gaussian\nparticles. Namely, we explore the fluid phase diagram of a model in which\nparticles interact via the generalized exponential potential u(r)=\\epsilon\nexp[-(r/\\sigma)^n], with a softness exponent n slightly larger than 2. In\naddition to the well-known anomaly associated to reentrant melting, the\nstructure and dynamics of the fluid display two additional anomalies, which are\nvisible in the isothermal variation of the structure factor and diffusivity.\nThese features are correlated to the appearance of dimers in the fluid phase\nand to the subsequent modification of the cluster structure upon compression.\nWe corroborate these results through an analysis of the local minima of the\npotential energy surface, in which clusters appear as much tighter\nconglomerates of particles. We find that reentrant melting and clustering\ncoexist for softness exponents ranging from 2^+ up to values relevant for the\ndescription of amphiphilic dendrimers, i.e., n=3.",
        "positive": "Unwinding of circular helicoidal molecules versus size: The thermodynamical stability of a set of circular double helical molecules\nis analyzed by path integral techniques. The minicircles differ only in\n\\textit{i)} the radius and \\textit{ii)} the number of base pairs ($N$) arranged\nalong the molecule axis. Instead, the rise distance is kept constant. For any\nmolecule size, the computational method simulates a broad ensemble of possible\nhelicoidal configurations while the partition function is a sum over the path\ntrajectories describing the base pair fluctuational states. The stablest\nhelical repeat of every minicircle is determined by free energy minimization.\nWe find that, for molecules with $N$ larger than $100$, the helical repeat\ngrows linearly with the size and the twist number is constant. On the other\nhand, by reducing the size below $100$ base pairs, the double helices sharply\nunwind and the twist number drops to one for $N=\\,20$. This is predicted as the\nminimum size for the existence of helicoidal molecules in the closed form. The\nhelix unwinding appears as a strategy to release the bending stress associated\nto the circularization of the molecules."
    },
    {
        "anchor": "The model of randomly distributed polydisperse overlapping spheres: A model of randomly distributed overlapping spheres of different radii is\nrepresented to describe a heterogeneous porous medium. Two-particle correlation\nfunction of the relative position of pores of different radii in the medium\nspace was calculated and detailed analysis was carried out. The model allows to\ncharacterize the disordered porous medium with the number of nearest neighbors,\nthe area of all mouths that connect pore with the neighboring pores. These\nparamaters depend on the pore size and porosity and --- in addition to the\nspecific surface area, porosity, and percolation threshold and the distribution\nfunction of pore size.",
        "positive": "Calculation of the Dimer Equilibrium Constant of Heavy Water Saturated\n  Vapor: Water is the most common substance on Earth.The discovery of heavy water and\nits further study have shown that the change of hydrogen for deuterium leads to\nthe significant differences in their properties.The triple point temperature of\nheavy water is higher,at the same time the critical temperature is\nlower.Experimental values of the second virial coefficient of the EOS for the\nvapor of normal and heavy water differ at all temperatures.This fact can\ninfluence the values of the dimerization constant for the heavy water vapor.The\nequilibrium properties of the dimerization process are described with the\nmethods of chemical thermodynamics.The chemical potentials for monomers (m) and\ndimers (d)are the functions of their concentrations.The interactions of\nmonomer-dimer and dimer-dimer types are taken into account within the solution\nof equation for chemical potentials.The obtained expression for the\ndimerization constant contains the contributions of these types.The averaged\npotentials are modeled by the Sutherland potential.Theoretical values of the\ndimerization constant for the heavy water vapor at different temperatures are\ncompared to those for normal water.We see the exceeding of the values for the\nheavy water at all temperatures.This fact is in good agreement with all\nexperimental data that is available.The excess is related to the differences in\nthe character of the heat excitations of the dimers of normal and heavy\nwater,their rotational constants and energy of their vibrational\nexcitations.Significant role is also played by the monomer-dimer and\ndimer-dimer interactions."
    },
    {
        "anchor": "Rheotaxis of chiral bacteria: from single-cell behavior to a\n  population-level description: Due to their morphology, the dynamics of bacteria suspended in media can\nexhibit complex behaviors. In the presence of a shear, swimming bacteria\nexperience a drift perpendicular to the shear plane. This drift, termed\nrheotaxis, is studied here semi-analytically, numerically and experimentally.\nWe find the dependency of bacterial orientation and bacterial speed on the\nshear rate, in the presence of rotational diffusion. This enables us to show\nthat the drift speed of bacteria perpendicular to the shear is predominantly\ndue to bacterial propulsion, and not rheotactic forces. Comparing the drift\nspeed of bacteria and diffusion leads to the definition of a P\\'{e}clet number.\nThe rheotactic effect increases with the shear, reaching a plateau at very\nlarge P\\'{e}clet numbers, in good agreement with experiments of rheotaxis\nperformed in microfluidic droplets.",
        "positive": "Charge transport through bio-molecular wires in a solvent: Bridging\n  molecular dynamics and model Hamiltonian approaches: We present a hybrid method based on a combination of quantum/classical\nmolecular dynamics (MD) simulations and a mod el Hamiltonian approach to\ndescribe charge transport through bio-molecular wires with variable lengths in\npresence o f a solvent. The core of our approach consists in a mapping of the\nbio-molecular electronic structure, as obtained f rom density-functional based\ntight-binding calculations of molecular structures along MD trajectories, onto\na low di mensional model Hamiltonian including the coupling to a dissipative\nbosonic environment. The latter encodes fluctuat ion effects arising from the\nsolvent and from the molecular conformational dynamics. We apply this approach\nto the c ase of pG-pC and pA-pT DNA oligomers as paradigmatic cases and show\nthat the DNA conformational fluctuations are essential in determining and\nsupporting charge transport."
    },
    {
        "anchor": "Thermal noise influences fluid flow in thin films during spinodal\n  dewetting: Experiments on dewetting thin polymer films confirm the theoretical\nprediction that thermal noise can strongly influence characteristic time-scales\nof fluid flow and cause coarsening of typical length scales. Comparing the\nexperiments with deterministic simulations, we show that the Navier-Stokes\nequation has to be extended by a conserved bulk noise term to accomplish the\nobserved spectrum of capillary waves. Due to thermal fluctuations the spectrum\nchanges from an exponential to a power law decay for large wavevectors. Also\nthe time evolution of the typical wavevector of unstable perturbations exhibits\nnoise induced coarsening that is absent in deterministic hydrodynamic flow.",
        "positive": "Synchronous whirling of spinning homogeneous elastic cylinders: linear\n  and weakly non-linear analyses: Stationary whirling of slender and homogeneous (continuous) elastic shafts\nrotating around their axis, with pin-pin boundary condition at the ends, is\nrevisited by considering the complete deformations in the cross section of the\nshaft. The stability against a synchronous sinusoidal disturbance of any wave\nlength is investigated and the analytic expression of the buckling amplitude is\nderived in the weakly non-linear regime by considering both geometric and\nmaterial (hyper-elastic) non-linearities. The bifurcation is super-critical in\nthe long wave length domain for any elastic constitutive law, and sub-critical\nin the short wave length limit for a limited range of non-linear material\nparameters."
    },
    {
        "anchor": "Twirling DNA Rings - Swimming Nanomotors Ready for a Kickstart: We propose a rotary DNA nanomachine that shows a continuous rotation with a\nfrequency of 10^2 -10^4 Hz. This motor consists of a DNA ring whose elastic\nfeatures are tuned such that it can be externally driven via a periodic\ntemperature change. As a result the ring propels itself through the fluid with\na speed up to microns per second.",
        "positive": "Towards a continuum model for particle-induced velocity fluctuations in\n  suspension flow through a stenosed geometry: Non-particulate continuum descriptions allow for computationally efficient\nmodeling of suspension flows at scales that are inaccessible to more detailed\nparticulate approaches. It is well known that the presence of particles\ninfluences the effective viscosity of a suspension and that this effect has\nthus to be accounted for in macroscopic continuum models. The present paper\naims at developing a non-particulate model that reproduces not only the\nrheology but also the cell-induced velocity fluctuations, responsible for\nenhanced diffusivity. The results are obtained from a coarse-grained blood\nmodel based on the lattice Boltzmann method. The benchmark system comprises a\nflow between two parallel plates with one of them featuring a smooth obstacle\nimitating a stenosis. Appropriate boundary conditions are developed for the\nparticulate model to generate equilibrated cell configurations mimicking an\ninfinite channel in front of the stenosis. The averaged flow field in the bulk\nof the channel can be described well by a non-particulate simulation with a\nmatched viscosity. We show that our proposed phenomenological model is capable\nto reproduce many features of the velocity fluctuations."
    },
    {
        "anchor": "On the Disclination Lines of Nematic Liquid Crystals: Defects in liquid crystals are of great practical importance and theoretical\ninterest. Despite tremendous efforts, predicting the location and transition of\ndefects under various topological constraint and external field remains to be a\nchallenge. We investigate defect patterns of nematic liquid crystals confined\nin three-dimensional spherical droplet and two-dimensional disk under different\nboundary conditions, within the Landau-de Gennes model. We implement a spectral\nmethod that numerically solves the Landau-de Gennes model with high accuracy,\nwhich allows us to study the detailed static structure of defects. We observe\nfive types of defect structures. Among them the 1/2-disclination lines are the\nmost stable structure at low temperature. Inspired by numerical results, we\nobtain the profile of disclination lines analytically. Moreover, the connection\nand difference between defect patterns under the Landau-de Gennes model and the\nOseen-Frank model are discussed. Finally, four conjectures are made to\nsummarize some important characteristics of defects in the Landau-de Gennes\ntheory. This work is a continuing effort to deepen our understanding on defect\npatterns in nematic liquid crystals.",
        "positive": "Homogeneous nucleation of colloidal melts under the influence of\n  shearing fields: We study the effect of shear flow on homogeneous crystal nucleation, using\nBrownian Dynamics simulations in combination with an umbrella sampling like\ntechnique. The symmetry breaking due to shear results in anisotropic radial\ndistribution functions. The homogeneous shear rate suppresses crystal\nnucleation and leads to an increase of the size of the critical nucleus. These\nobservations can be described by a simple, phenomenological extension of\nclassical nucleation theory. In addition, we find that nuclei have a\npreferential orientation with respect to the direction of shear. On average the\nlongest dimension of a nucleus is along the vorticity direction, while the\nshortest dimension is preferably perpendicular to that and slightly tilted with\nrespect to the gradient direction."
    },
    {
        "anchor": "On Mechanical Response of Macro- and Microfiller-Reinforced Polymer:\n  Young Modulus and Shear Wave Velocity: The problem of effective shear and bulk moduli, of an effective Poison's\nratio and of an effective dielectric response in microcomposites of the\nferroelastic-dielectric type was studied by us recently. Recently one of us, M.\nHudak, studied static mechanical properties of the EVA material theoretically\nand experimentally. We extend our mentioned study of mechanical response of\nmicrocomposites of the type ferrolastics - dielectrics to study of Young\nmodulus and shear wave velocity.",
        "positive": "Thermoresponsive micropatterned substrates for single cell studies: We describe the design of micropatterned surfaces for single cell studies,\nbased on thermoresponsive polymer brushes. We show that brushes made of\npoly(N-isopropylacrylamide) grafted at high surface density display excellent\nprotein and cell anti-adhesive properties. Such brushes are readily patterned\nat the micron scale via deep UV photolithography. A proper choice of the\nadhesive pattern shapes, combined with the temperature-dependent swelling\nproperties of PNIPAM, allow us to use the polymer brush as a microactuator\nwhich induces cell detachment when the temperature is reduced below 32degC."
    },
    {
        "anchor": "Thixotropy, non-monotonic stress relaxation, and the second law of\n  thermodynamics: Many thixo-viscoelastic materials have been reported to undergo enhancement\nin elastic modulus with time and decrease in the same under application of\ndeformation field. Incorporation of this feature in a viscoelastic structural\nkinetic model has an apparent possibility of violating the second law of\nthermodynamics. Furthermore, in a related experimental observation, stress has\nbeen reported to undergo a non-monotonic change as a function of time under the\napplication of constant strain. We analyze both these scenarios through a\nstructural kinetic model that shows viscoelastic aging but undergoes\nrejuvenation only due to the viscous rate of strain. We observe that such\nformalism does not violate the second law. Interestingly, the proposed simple\nformalism predicts the experimental observation of the non-monotonic stress\nrelaxation very well.",
        "positive": "Transition to coarsening for confined one-dimensional interfaces with\n  bending rigidity: We discuss the nonlinear dynamics and fluctuations of interfaces with bending\nrigidity under the competing attractions of two walls with arbitrary\npermeabilities. This system mimics the dynamics of confined membranes. We use a\ntwo-dimension hydrodynamic model, where membranes are effectively\none-dimensional objects. In a previous work [T. Le Goff et al, Phys. Rev. E 90,\n032114 (2014)], we have shown that this model predicts frozen states caused by\nbending rigidity-induced oscillatory interactions between kinks (or domain\nwalls). We here demonstrate that in the presence of tension, potential\nasymmetry, or thermal noise, there is a finite threshold above which frozen\nstates disappear, and perpetual coarsening is restored. Depending on the\ndriving force, the transition to coarsening exhibits different scenarios.\nFirst, for membranes under tension, small tensions can only lead to transient\ncoarsening or partial disordering, while above a finite threshold, membrane\noscillations disappear and perpetual coarsening is found. Second, potential\nasymmetry is relevant in the non-conserved case only, i.e. for permeable walls,\nwhere it induces a drift force on the kinks, leading to a fast coarsening\nprocess via kink-antikink annihilation. However, below some threshold, the\ndrift force can be balanced by the oscillatory interactions between kinks, and\nfrozen adhesion patches can still be observed. Finally, at long times, noise\nrestores coarsening with standard exponents depending on the permeability of\nthe walls. However, the typical time for the appearance of coarsening exhibits\nan Arrhenius form. As a consequence, a finite noise amplitude is needed in\norder to observe coarsening in observable time."
    },
    {
        "anchor": "Sediment creep triggered by porous flow: Quasi-2D experiments of a submerged sediment layer creeping downward were\nperformed, varying the channel tilt and a porous flow under the respective\nthresholds for yielding. Logarithmic decay rates of the deformation are\nobserved, with the rate increasing with both control parameters. A new\ndimensionless parameter, $P^*$, accounting for both mean porous flow and\ngravity force effects on particle motion, allows a collapse of all the\ndeformation results on a single curve. Two distinct creep regimes are\nidentified, and correspond to a systematic change of the void size distribution\nas $P^*$ increases.",
        "positive": "Dynamics of a membrane interacting with an active wall: Active motions of a biological membrane can be induced by non-thermal\nfluctuations that occur in the outer environment of the membrane. We discuss\nthe dynamics of a membrane interacting hydrodynamically with an active wall\nthat exerts random velocities on the ambient fluid. Solving the hydrodynamic\nequations of a bound membrane, we first derive a dynamic equation for the\nmembrane fluctuation amplitude in the presence of different types of walls.\nMembrane two-point correlation functions are calculated for three different\ncases; (i) a static wall, (ii) an active wall, and (iii) an active wall with an\nintrinsic time scale. We focus on the mean squared displacement (MSD) of a\ntagged membrane describing the Brownian motion of a membrane segment. For the\nstatic wall case, there are two asymptotic regimes of MSD ($\\sim t^{2/3}$ and\n$\\sim t^{1/3}$) when the hydrodynamic decay rate changes monotonically. In the\ncase of an active wall, the MSD grows linearly in time ($\\sim t$) in the early\nstage, which is unusual for a membrane segment. This linear-growth region of\nthe MSD is further extended when the active wall has a finite intrinsic time\nscale."
    },
    {
        "anchor": "Iso-Flux Tension Propagation Theory of Driven Polymer Translocation: The\n  Role of Initial Configurations: We investigate the dynamics of pore-driven polymer translocation by\ntheoretical analysis and molecular dynamics (MD) simulations. Using the tension\npropagation theory within the constant flux approximation we derive an explicit\nequation of motion for the tension front. From this we derive a scaling\nrelation for the average translocation time $\\tau$, which captures the\nasymptotic result $\\tau \\propto N_0^{1+\\nu}$, where $N_0$ is the chain length\nand $\\nu$ is the Flory exponent. In addition, we derive the leading\ncorrection-to-scaling term to $\\tau$ and show that all terms of order\n$N_0^{2\\nu}$ exactly cancel out, leaving only a finite-chain length correction\nterm due to the effective pore friction, which is linearly proportional to\n$N_0$. We use the model to numerically include fluctuations in the initial\nconfiguration of the polymer chain in addition to thermal noise. We show that\nwhen the {\\it cis} side fluctuations are properly accounted for, the model not\nonly reproduces previously known results but also considerably improves the\nestimates of the monomer waiting time distribution and the time evolution of\nthe translocation coordinate $s(t)$, showing excellent agreement with MD\nsimulations.",
        "positive": "Ion exchange phase transitions in \"doped\" water--filled channels: Ion transport through narrow water--filled channels is impeded by a high\nelectrostatic barrier. The latter originates from the large ratio of the\ndielectric constants of the water and a surrounding media. We show that\n``doping'', i.e. immobile charges attached to the walls of the channel,\nsubstantially reduces the barrier. This explains why most of the biological ion\nchannels are ``doped''. We show that at rather generic conditions the channels\nmay undergo ion exchange phase transitions (typically of the first order). Upon\nsuch a transition a finite latent concentration of ions may either enter or\nleave the channel, or be exchanged between the ions of different valences. We\ndiscuss possible implications of these transitions for the Ca-vs.-Na\nselectivity of biological Ca channels. We also show that transport of divalent\nCa ions is assisted by their fractionalization into two separate excitations."
    },
    {
        "anchor": "Compressible or incompressible blend of interacting monodisperse star\n  and linear polymers near a surface: We consider a lattice model of a mixture of repulsive, attractive, or neutral\nmonodisperse star (species A) and linear (species B) polymers with a third\nmonomeric species C, which may represent free volume. The mixture is next to a\nhard, infinite plate whose interactions with A and C can be attractive,\nrepulsive, or neutral. These two interactions are the only parameters necessary\nto specify the effect of the surface on all three components. We numerically\nstudy monomer density profiles using the method of Gujrati and Chhajer that has\nalready been previously applied to study polydisperse and monodisperse\nlinear-linear blends next to surfaces. The resulting density profiles always\nshow an enrichment of linear polymers in the immediate vicinity of the surface,\ndue to entropic repulsion of the star core. However, the integrated surface\nexcess of star monomers is sometimes positive, indicating an overall enrichment\nof stars. This excess increases with the number of star arms only up to a\ncertain critical number and decreases thereafter. The critical arm number\nincreases with compressibility (bulk concentration of C). The method of Gujrati\nand Chhajer is computationally ultrafast and can be carried out on a PC, even\nin the incompressible case, when simulations are unfeasible. Calculations of\ndensity profiles usually take less than 20 minutes on PCs.",
        "positive": "Capillary Electrophoresis as a Fundamental Probe of Polymer Dynamics: Capillary electrophoresis has long been been recognized as a powerful\nanalytic tool. Here it is demonstrated that the same capillary electrophoretic\nexperiments also reveal dynamic properties of the polymer solutions being used\nas the support medium. The dependence of the electrophoretic mobility on the\nsize of the probe and the properties of the matrix polymers shows a unity of\nbehavior between electrophoresis and other methods of studying polymer\nproperties."
    },
    {
        "anchor": "Quantitative Fluorescence Excitation Spectra for Synthetic Eumelanin: Previously reported excitation spectra for eumelanin are sparse and\ninconsistent. Moreover, these studies have failed to account for probe beam\nattenuation and emission reabsorption within the samples, making them\nqualitative at best. We report for the first time quantitative excitation\nspectra for synthetic eumelanin, acquired for a range of solution\nconcentrations and emission wavelengths. Our data indicate that probe beam\nattenuation and emission reabsorption significantly affect the spectra even in\nlow-concentration eumelanin solutions and that previously published data do not\nreflect the true excitation profile. We apply a correction procedure\n(previously applied to emission spectra) to account for these effects.\nApplication of this procedure reconstructs the expected relationship of signal\nintensity with concentration, and the normalised spectra show a similarity in\nform to the absorption profiles. These spectra reveal valuable information\nregarding the photophysics and photochemistry of eumelanin. Most notably, an\nexcitation peak at 365 nm (3.40 eV), whose position is independent of emission\nwavelength, is possibly attributable to a DHICA component singly linked to a\npolymeric structure.",
        "positive": "Time traces of individual kinesin motors suggest functional\n  heterogeneity: Conventional analysis of in vitro assays of motor proteins rests on the\nassumption that all proteins with the same chemical composition function\nidentically; however molecule-to-molecule variation is often seen even in\nwell-controlled experiments. In an effort to obtain a statistically meaningful\nset of time traces that simultaneously avoid any experimental artifacts, we\nperformed quantum-dot labeled kinesin experiments on both surface and levitated\nmicrotubules. Similar to glassy systems, we found that mean velocities of\nindividual kinesin motors vary widely from one motor to another, the variation\nof which is greater than that expected from the stochastic variation of\nstepping times. In the presence of heterogeneity, an ensemble-averaged quantity\nsuch as diffusion constant or randomness parameter is ill-defined. We propose\nto analyze heterogeneous data from single molecule measurements by decomposing\nthem into homogeneous subensembles."
    },
    {
        "anchor": "Waterlike thermodynamic anomalies in a repulsive-step potential system: We report a computer-simulation study of the equilibrium phase diagram of a\nthree-dimensional system of particles with a repulsive step potential. The\nphase diagram is obtained using free-energy calculations. At low temperatures,\nwe observe a number of distinct crystal phases. We show that at certain values\nof the potential parameters the system exhibits the water-like thermodynamic\nanomalies: density anomaly and diffusion anomaly. The anomalies disappear with\nincreasing the repulsive step width: their locations move to the region inside\nthe crystalline phase.",
        "positive": "Casimir forces in binary liquid mixtures: If two ore more bodies are immersed in a critical fluid critical fluctuations\nof the order parameter generate long ranged forces between these bodies. Due to\nthe underlying mechanism these forces are close analogues of the well known\nCasimir forces in electromagnetism. For the special case of a binary liquid\nmixture near its critical demixing transition confined to a simple parallel\nplate geometry it is shown that the corresponding critical Casimir forces can\nbe of the same order of magnitude as the dispersion (van der Waals) forces\nbetween the plates. In wetting experiments or by direct measurements with an\natomic force microscope the resulting modification of the usual dispersion\nforces in the critical regime should therefore be easily detectable. Analytical\nestimates for the Casimir amplitudes Delta in d=4-epsilon are compared with\ncorresponding Monte-Carlo results in d=3 and their quantitative effect on the\nthickness of critical wetting layers and on force measurements is discussed."
    },
    {
        "anchor": "Multi-speckle diffusing wave spectroscopy with a single mode detection\n  scheme: We present a detection scheme for diffusing wave spectroscopy (DWS) based on\na two cell geometry that allows efficient ensemble averaging. This is achieved\nby putting a fast rotating diffuser in the optical path between laser and\nsample. We show that the recorded (multi-speckle) correlation echoes provide an\nensemble averaged signal that does not require additional time averaging. We\nfind the performance of our experimental scheme comparable or even superior to\ncamera based multi-speckle techniques that rely on direct spatial averaging.\nFurthermore, combined with traditional two-cell DWS, the full intensity\nautocorrelation function can be measured with a single experimental setup\ncovering more than 10 decades in correlation time.",
        "positive": "Two-step deswelling in the Volume Phase Transition of thermoresponsive\n  microgels: Thermoresponsive microgels are one of the most investigated class of soft\ncolloids, thanks to their ability to undergo a Volume Phase Transition (VPT)\nclose to ambient temperature. However, this fundamental phenomenon still lacks\na detailed microscopic understanding, particularly regarding the presence and\nthe role of charges in the deswelling process. Here we fill this gap by\ncombining experiments and simulations to show that the microgel collapse does\nnot happen in a homogeneous fashion, but through a two-step mechanism, entirely\nattributable to electrostatic effects. The signature of this phenomenon is the\nemergence of a minimum in the ratio between gyration and hydrodynamic radii at\nthe VPT. Thanks to simulations of several microgels with different cross-linker\nconcentrations, charge contents and charge distributions, we build a unifying\nmaster-curve able to predict the two-step deswelling. Our results have direct\nrelevance on fundamental soft condensed matter science and on microgel\napplications ranging from materials to biomedical technologies."
    },
    {
        "anchor": "Bridging the Gap between Crosslinking Chemistry and Directed Assembly of\n  Metasurfaces Using Electrohydrodynamic Flow: Advances in understanding chemical and physical driving forces in\nself-assembly allow the fabrication of unique nanoarchitectures with\nsubwavelength building blocks as the basis for plasmonic and metamaterial\ndevices. Chemical crosslinking of colloidal nanospheres has produced among the\nsmallest gap spacings, necessary to obtain regions of greatly enhanced electric\nfield, hotspots, which are critical to tailor light-matter interactions.\nHowever, obtaining uniform electromagnetic response of dense nanoantennas over\nlarge area for use in devices remains challenging. In this work,\nelectrohydrodynamic (EHD) flow and chemical crosslinking is combined to form\ndense, yet discrete, Au nanosphere clusters (oligomers) on a working electrode.\nEHD provides a long range driving force to bring nanospheres together and\nanhydride crosslinking yields 0.9 nm gap spacings. Using selective chemistry,\nnanospheres are simultaneously crosslinked onto a block copolymer template,\nproducing oligomers with a narrower wavelength band width and higher hotspot\nintensity than monolayer structures produced without a template. We investigate\nnanoantenna response via full wave simulations, ultraviolet-visible\nspectroscopy, and surface enhanced Raman scattering (SERS). Nanoantennas\nexhibit uniform hotspot intensity and gap spacing. Simulations show field\nenhancements of 600, correlating well with measured average SERS enhancement of\n1.4x10^9. Nanoantenna substrates produce a SERS signal with a relative standard\ndeviation of 10% measured over a 1 mm2 area, crucial for nano-optical devices\nsuch as optical sensors, among other applications. Understanding long range\n(EHD flow) and short range (chemical crosslinking) driving forces provides the\ncontrol for assembling colloidal nanoparticles in architectures for large area\nplasmonic and metasurface device fabrication.",
        "positive": "A tube concept in rubber viscoelasticity: A constitutive model is derived for the time-dependent response of\nparticle-reinforced elastomers at finite strains. An amorphous rubbery polymer\nis treated as a network of long chains linked by permanent junctions (chemical\ncrosslinks, entanglements and filler particles). A strand between two\nneighboring junctions is thought of as a sequence of mers whose motion is\nrestricted to some tube by surrounding macromolecules. Unlike the conventional\napproach that presumes the cross-section of the tube to be constant, we\npostulate that its radius strongly depends on the longitudinal coordinate. This\nimplies that a strand may be modeled as a sequence of segments whose thermal\nmotion is totally frozen by the environment (bottle-neck points of the tube)\nbridged by threads of mers which go through all possible configurations during\nthe characteristic time of a test. Thermal fluctuations affect the tube's\nradius, which results in freezing and activation of regions with high molecular\nmobility (RHMs). The viscoelastic response of an elastomer is associated with\nthermally activated changes in the number of RHMs in strands. Stress-strain\nrelations for a rubbery polymer at finite strains and kinetic equations for the\nconcentrations of RHMs are developed by using the laws of thermodynamics. At\nsmall strains these relations are reduced to the conventional integral\nconstitutive equation in linear viscoelasticity with a novel scaling law for\nrelaxation times. The governing equation is determined by 5 adjustable\nparameters which are found by fitting experimental data in tensile dynamic\ntests on a carbon black filled natural rubber vulcanizate."
    },
    {
        "anchor": "In situ small-angle X-ray scattering reveals strong condensation of DNA\n  origami during silicification: The silicification of DNA origami structures increases their mechanical and\nthermal stability and provides chemical protection. So far, it is unclear how\nsilicification affects the internal structure of the DNA origami and whether\nthe whole DNA framework is embedded or if silica just forms an outer shell. By\nusing in situ small-angle X-ray scattering (SAXS), we show that the\nnet-cationic silica precursor TMAPS induces substantial condensation of the DNA\norigami, which is further enhanced by the addition of TEOS at early reaction\ntimes to an almost 10 % size reduction. We identify the SAXS Porod invariant as\na reliable, model-free parameter for the evaluation of the amount of silica\nformation at a given time. Contrast matching of the DNA double helix Lorentzian\npeak reveals that silica growth also occurs on the inner surfaces of the\norigami. The less polar silica forming within the origami structure, replacing\nmore than 40 % of the internal hydration water causes a hydrophobic effect:\norigami condensation. In the maximally condensed state, thermal stabilization\nof the origami up to 60 {\\deg}C could be observed. If the reaction is driven\nbeyond this point, the overall size of the silicified origami increases again\ndue to more and more silica deposition on the DNA origami. DNA origami objects\nwith flat surfaces show a strong tendency towards aggregation during\nsilicification, presumably driven by the very same entropic forces causing\ncondensation. Our studies provide novel insights into the silicification\nreaction and hints for the formulation of optimized reaction protocols.",
        "positive": "Derivation of the Matalon-Packter law for Liesegang patterns: Theoretical models of the Liesegang phenomena are studied and simple\nexpressions for the spacing coefficients characterizing the patterns are\nderived. The emphasis is on displaying the explicit dependences on the\nconcentrations of the inner- and the outer-electrolytes. Competing theories\n(ion-product supersaturation, nucleation and droplet growth, induced sol-\ncoagulation) are treated with the aim of finding the distinguishing features of\nthe theories. The predictions are compared with experiments and the results\nsuggest that the induced sol-coagulation theory is the best candidate for\ndescribing the experimental observations embodied in the Matalon-Packter law."
    },
    {
        "anchor": "Electrostatic bending response of a charged helix: We explore the electrostatic bending response of a chain of charged particles\nconfined on a finite helical filament. We analyze how the energy difference\n$\\Delta E$ between the bent and the unbent helical chain scales with the length\nof the helical segment and the radius of curvature and identify features that\nare not captured by the standard notion of the bending rigidity, normally used\nas a measure of bending tendency in the linear response regime. Using instead\n$\\Delta E$ to characterize the bending response of the helical chain we\nidentify two regimes with qualitatively different bending behaviors for the\nground state configuration: the regime of small and the regime of large\nradius-to-pitch ratio, respectively. Within the former regime, $\\Delta E$\nchanges smoothly with the variation of the system parameters. Of particular\ninterest are its oscillations with the number of charged particles encountered\nfor commensurate fillings which yield length-dependent oscillations in the\npreferred bending direction of the helical chain. We show that the origin of\nthese oscillations is the non-uniformity of the charge distribution caused by\nthe long-range character of the Coulomb interactions and the finite length of\nthe helix. In the second regime of large values of the radius-to-pitch ratio,\nsudden changes in the ground state structure of the charges occur as the system\nparameters vary, leading to complex and discontinuous variations in the ground\nstate bending response $\\Delta E$.",
        "positive": "On standardised moments of force distribution in simple liquids: The force distribution of a tagged atom in a Lennard-Jones fluid in the\ncanonical ensemble is studied with a focus on its dependence on inherent\nphysical parameters: number density ($n$) and temperature ($T$). Utilising\nstructural information from molecular dynamics simulations of the Lennard-Jones\nfluid, explicit analytical expressions for the dependence of standardised force\nmoments on $n$ and $T$ are derived. Leading order behaviour of standardised\nmoments of the force distribution are obtained in the limiting cases of small\ndensity ($n \\rightarrow 0$) and low temperature ($T \\rightarrow 0$), while the\nvariations in the standardised moments are probed for general $n$ and $T$ using\nmolecular dynamics simulations. Clustering effects are seen in molecular\ndynamics simulations and their effect on these standardised moments is\ndiscussed."
    },
    {
        "anchor": "Long-time relaxation dynamics in nematic and smectic liquid crystals of\n  soft-repulsive colloidal rods: Understanding the relaxation dynamics of colloidal suspensions is crucial to\nidentify the elements that influence the mobility of their constituents, assess\ntheir macroscopic response across the relevant time and length scales, and thus\ndisclose the fundamentals underpinning their exploitation in formulation\nengineering. In this work, we specifically assess the impact of long-ranged\nordering on the relaxation dynamics of suspensions of soft-repulsive rod-like\nparticles, which are able to self-organise into nematic and smectic\nliquid-crystalline phases. By performing Dynamic Monte Carlo simulations, we\nanalyse the effect of translational and orientational order on the diffusion of\nthe rods along the relevant directions imposed by the morphology of the\nbackground phases. To provide a clear picture of the resulting dynamics, we\nassess their dependence on temperature, which can dramatically determine the\nresponse time of the system relaxation and the self-diffusion coefficients of\nthe rods. The computation of the van Hove correlation functions allows us to\nidentify the existence of rods that diffuse significantly faster than the\naverage and whose concentration can be accurately adjusted by a suitable choice\nof temperature.",
        "positive": "Rotational hot Brownian motion: We establish an effective Markov theory for the rotational Brownian motion of\nhot nanobeads and nanorods. Compact analytical expressions for the effective\ntemperature and friction are derived from the fluctuating hydrodynamic\nequations of motion. They are verified by comparison with recent measurements\nand with GPU powered parallel molecular dynamics simulations over a wide\ntemperature range. This provides unique insights into the physics of hot\nBrownian motion and an excellent starting point for further experimental tests\nand applications involving laser-heated nanobeads, nanorods and Janus\nparticles."
    },
    {
        "anchor": "Stochastic Hydrodynamics of Complex Fluids: Discretisation and Entropy\n  Production: Many complex fluids can be described by continuum hydrodynamic field\nequations, to which noise must be added in order to capture thermal\nfluctuations. In almost all cases, the resulting coarse-grained stochastic\npartial differential equations carry a short-scale cutoff -- which is also\nreflected in numerical discretisation schemes. We draw together our recent\nfindings concerning the construction of such schemes and the interpretation of\ntheir continuum limits, focusing for simplicity on models with a purely\ndiffusive scalar field, such as `Model B' which describes phase separation in\nbinary fluid mixtures. We address the requirement that the steady state entropy\nproduction rate (EPR) must vanish for any stochastic hydrodynamic model in\nthermal equilibrium. Only if this is achieved can the given discretisation\nscheme be relied upon to correctly calculate the nonvanishing EPR for `active\nfield theories' in which new terms are deliberately added to the fluctuating\nhydrodynamic equations that break detailed balance. To compute the correct\nprobabilities of forward and time-reversed paths (whose ratio determines the\nEPR) we must make a careful treatment of so-called `spurious drift' and other\nclosely related terms that depend on the discretisation scheme. We show that\nsuch subtleties can arise not only in the temporal discretisation (as is well\ndocumented for stochastic ODEs with multiplicative noise) but also from spatial\ndiscretisation, even when noise is additive, as most active field theories\nassume. We then review how such noise can become multiplicative, via\noff-diagonal couplings to additional fields that encode thermodynamically the\nunderlying chemical processes responsible for activity. In this case the\nspurious drift terms need careful accounting, not just to evaluate correctly\nthe EPR, but also to numerically implement the Langevin dynamics itself.",
        "positive": "Topological defects and shape of aromatic self-assembled vesicles: We show that the stacking of flat aromatic molecules on a curved surface\nresults in topological defects. We consider, as an example, spherical vesicles,\nself-assembled from molecules with 5- and 6-thiophene cores. We predict that\nthe symmetry of the molecules influences the number of topological defects and\nthe resulting equilibrium shape."
    },
    {
        "anchor": "Approach of the constitutive material behaviour of textile composites\n  through simulation: A complete approach for the determination of the complex constitutive\nbehaviour of textile composites through finite element simulation is presented\nin this paper. In this work, simulations of different loading cases are carried\nout on small samples of textile composites, taking into account all individual\nfibers of the fabric and interactions taking place between them. The most\ndelicate issue is related to the modelling of contact-friction interactions\nbetween fibers,and the solution of the nonlinear problem that follows up by the\nmeans of robust algorithms. The efficiency of these algorithms, and the\nincrease of capacities of high performance computing, allow to simulate samples\nmade of several hundreds of interlocked fibers.",
        "positive": "Shear flow of non-Brownian rod-sphere mixtures near jamming: We use the discrete element method, taking particle contact and hydrodynamic\nlubrication into account, to unveil the shear rheology of suspensions of\nfrictionless non-Brownian rods in the dense packing fraction regime. We find\nthat, analogously to the random close packing volume fraction, the shear-driven\njamming point of this system varies in a non-monotonic fashion as a function of\nthe rod aspect ratio. The latter strongly influences how the addition of\nrod-like particles affects the rheological response of a suspension of\nfrictionless non-Brownian spheres to an external shear flow. At fixed values of\nthe total (rods plus spheres) packing fraction, the viscosity of the suspension\nis reduced by the addition of ``short\" ( $\\leq 2$) rods but is instead\nincreased by the addition of ``long\" ( $\\geq2$) rods. A mechanistic\ninterpretation is provided in terms of packing and excluded-volume arguments."
    },
    {
        "anchor": "Guanidinium can both Cause and Prevent the Hydrophobic Collapse of\n  Biomacromolecules: A combination of Fourier transform infrared and phase transition measurements\nas well as molecular computer simulations, and thermodynamic modeling were\nperformed to probe the mechanisms by which guanidinium salts influence the\nstability of the collapsed versus uncollapsed state of an elastin-like\npolypeptide (ELP), an uncharged thermoresponsive polymer. We found that the\ncation's action was highly dependent upon the counteranion with which it was\npaired. Specifically, Gnd+ was depleted from the ELP/water interface and was\nfound to stabilize the collapsed state of the macromolecule when paired with\nwell-hydrated anions such as sulfate. Stabilization in this case occurred via\nan excluded volume (or depletion) effect, whereby sulfate was strongly\npartitioned away from the ELP/water interface. Intriguingly, at low salt\nconcentrations, Gnd+ was also found to stabilize the collapsed state of the ELP\nwhen paired with SCN-, which is a strong binder for the ELP. In this case, the\nanion and cation were both found to be enriched in the collapsed state of the\npolymer. The collapsed state was favored because the Gnd+ crosslinked the\npolymer chains together. Moreover, the anion helped partition Gnd+ to the\npolymer surface. At higher salt concentrations (>1.5 M), GndSCN switched to\nstabilizing the uncollapsed state because a sufficient amount of Gnd+ and SCN-\npartitioned to the polymer surface to prevent cross-linking from occurring.\nFinally, in a third case, it was found that salts which interacted in an\nintermediate fashion with the polymer (e.g. GndCl) favored the uncollapsed\nconformation at all salt concentrations.",
        "positive": "Statistical mechanics of transport processes in active fluids: Equations\n  of hydrodynamics: The equations of hydrodynamics including mass, linear momentum, angular\nmomentum, and energy are derived by coarse-graining the microscopic equations\nof motion for systems consisting of rotary dumbbells driven by internal\ntorques."
    },
    {
        "anchor": "Programmable Active Janus Droplets Driven by Water/Alcohol Phase\n  Separation: We report the existence of self-propelled Janus droplets driven by phase\nseparation, which are able to deliver cargo in a programmable manner. The\nself-propelling droplets are initially formed by a water/ethanol mixture in a\nsqualane/monoolein solution, and evolve in up to three stages depending on\nethanol concentration. In the first stage, the droplet propulsion is generated\nby Marangoni flow originating from the solubilization of ethanol in the oily\nphase. During this process the droplets absorb surfactant molecules; in\ncombination with the continuous loss of ethanol this leads to a phase\nseparation of the water/ethanol/monoolein mixture and the formation of Janus\ndroplets, i.e. a water-rich droplet connected to an ethanol-rich droplet that\nis able to deliver cargo. We characterize the different evolution stages of\nself-propulsion by the flow field around the droplet that evolves from a weak\npusher, over a neutral swimmer, to a dimer of neutral swimmers. Finally, we\nutilize this active system to deliver DNA as a cargo. Tuning the delay time\nbefore phase separation, by varying the chemical composition of the droplets,\nseveral different cargo delivery processes can be programmed.",
        "positive": "A continuum model reproducing the multiple frequency crossovers in\n  acoustic attenuation in glasses: Structured metamaterials are at the core of extensive research, promising for\nacoustic and thermal engineering. Nevertheless, the computational cost required\nfor correctly simulating large systems imposes to use a continuous model to\ndescribe the effective behavior without knowing the atomistic details.\nCrucially, a correct description needs to describe both the extrinsic\ninterface-induced and the intrinsic atomic scale-originated phonon scattering,\nespecially when the component material is made of glass, a highly dissipative\nmaterial in which wave attenuation is strongly dependent on frequency as well\nas on temperature. In amorphous systems, the effective acoustic attenuation\ntriggered by multiple mechanisms is now well characterized and exhibits a\nnontrivial frequency dependence with a double crossover of power laws. In this\nwork, we propose a continuum viscoelastic model based on the hierarchical\nstrategy multi-scale approach, able to reproduce well the phonon attenuation in\na large frequency range, spanning three orders of magnitude from GHz to THz\nwith a $\\omega^2-\\omega^4-\\omega^2$ dependence, including the influence of\ntemperature."
    },
    {
        "anchor": "Morphology of cooperatively rearranging regions in active glass formers: Super cooled liquids display increasingly heterogeneous dynamics as\ntemperature is lowered towards the glass transition ($T_{g}$). A hallmark of\nthis dynamical heterogeneity is the spontaneous emergence of cooperative\nrearranging regions (CRRs) composed of fast moving particles. While these CRRs\nin passive glass formers have been explored in great detail, thus understanding\nis severely limited in active glass formers. The existing consensus on the\nmorphology of CRRs in a passive glass former prioritizes its fast subsets,\ncomposed of fast moving particles. In the present study, we focus on a\nsynthetic athermal active glass former and show an equal contribution for the\nmorphology of CRRs from slow subsets as well. Both these subsets exhibit an\nexponential distribution in their structure which strongly correlates with the\nexistence of CRRs. Interestingly, we also observe that the fractal dimensions\n($d_{\\text{f}}$) of these subsets share both string and compact like morphology\nthat tends to vary in opposite fashion with the control parameters, namely the\npersistent time ($\\tau_{p}$) and the effective temperature ($T_{\\text{eff}}$).\nThe fractal dimension $d_{\\text{f}}$ measures the roughness or put simply the\ncompactness of fractal objects at their boundaries. More precisely, molecules\nare loosely bound in a structure for which boundary is rough and thereby this\ncondition facilitates its structural change in terms of size and shape. It is\nalso a fact that any structural change is a signature of relaxation dynamics in\nthe context of glass forming liquids. Thus, in the present study, we observe a\nchange in $d_{\\text{f}}$ with $T_{\\text{eff}}$ and $\\tau_{p}$ from the insights\nof morphology variation that causes structural change, both in the BD limit and\nnon-equilibrium limit.",
        "positive": "Dynamical density functional theory for the drying and stratification of\n  binary colloidal dispersions: We develop a dynamical density functional theory based model for the drying\nof colloidal films on planar surfaces. We consider mixtures of two different\nsizes of hard-sphere colloids. Depending on the solvent evaporation rate and\nthe initial concentrations of the two species, we observe varying degrees of\nstratification in the final dried films. Our model predicts the various\nstructures described in the literature previously from experiments and computer\nsimulations, in particular the small-on-top stratified films. Our model also\nincludes the influence of adsorption of particles to the interfaces."
    },
    {
        "anchor": "A model for the fragmentation kinetics of crumpled thin sheets: As a confined thin sheet crumples, it spontaneously segments into flat facets\ndelimited by a network of ridges. Despite the apparent disorder of this\nprocess, statistical properties of crumpled sheets exhibit striking\nreproducibility. Experiments have shown that the total crease length accrues\nlogarithmically when repeatedly compacting and unfolding a sheet of paper.\nHere, we offer insight to this unexpected result by exploring the\ncorrespondence between crumpling and fragmentation processes. We identify a\nphysical model for the evolution of facet area and ridge length distributions\nof crumpled sheets, and propose a mechanism for re-fragmentation driven by\ngeometric frustration. This mechanism establishes a feedback loop in which the\nfacet size distribution informs the subsequent rate of fragmentation under\nrepeated confinement, thereby producing a new size distribution. We then\ndemonstrate the capacity of this model to reproduce the characteristic\nlogarithmic scaling of total crease length, thereby supplying a missing\nphysical basis for the observed phenomenon.",
        "positive": "Defect order in active nematics on a curved surface: We investigate the effects of extrinsic curvature on the turbulent behavior\nof a 2D active nematic confined to the surface of a cylinder. The surface of a\ncylinder has no intrinsic curvatrue and only extrinsic curvature. A nematic\nfield reacts to the extrinsic curvature by trying to align with the lowest\nprinciple curvature, in this case parallel to the long axis of the cylinder.\nWhen nematics are sufficiently active, there is a proliferation of defects\narising from a bend or splay instability depending on the nature of the active\nstress. The extrinsic curvature of the cylinder beaks the rotational symmetry\nof this process, implying that defects are created parallel or perpendicular to\nthe cylinder depending on whether the active nematic is contractile or\nextensile."
    },
    {
        "anchor": "Gold Nanoparticles Passivated with Functionalized Alkylthiols:\n  Simulations of Solvation in the Infinite Dilution Limit: Solvation of gold nanoparticles passivated with end group functionalized\nalkylthiols, namely CH$_3$, NH$_2$ or COOH is studied in solvents of varying\ndegrees of repulsion-dispersion and electrostatic interactions ranging from\nstrongly polar SPC/E water to modified hybrid water models, where the\nLennard-Jones contribution to the potential energy is enhanced relative to\nSPC/E to completely non-polar, decane. The effects due to solvent\nreorganization around the nanoparticle as a function of the ligand and solvent\nchemistry are monitored using the nanoparticle-solvent pair correlation\nfunctions and tetrahedral order parameter. The solvent penetration inside the\nligand shell is maximum for decane, indicating better solute-solvent\ninteraction in decane compared to other solvents. The COOH end group\nfunctionalized nanoparticle breaks the tetrahedral structure of water molecules\nmore as compared to other nanoparticles used in this study. The ligand\nreorganization and its effect on solvation are monitored using radial density\nprofiles (RDPs), radius of gyration ($R_g$) and ligand asymmetry parameter\n($\\langle \\Delta \\rangle$). RDP and $R_g$ values show significant stretching of\nligands in decane than in model waters, which is also consistent with $\\langle\n\\Delta \\rangle$. The ligand shell anisotropy for all nanoparticles is maximum\nin SPC/E water and minimum in decane. The isotropic potential of mean force\n($V_{PMF}(r)$) between two identical end group functionalized nanoparticles\nhave been calculated in vacuum, SPC/E water and H3.00 modified hybrid water,\nwhich consistently shows attractive well depth. Distance-dependent fluctuation\ndriven anisotropy has also been examined. The implications for self-assembly of\npassivated gold nanoparticles from aqueous dispersions as well as the\ndependence of calculated quantities on ligand and solvent chemistry are\nhighlighted.",
        "positive": "Refractive Index Matched Scanning and Detection of Soft Particle: We describe here how to apply the three dimensional imaging technique of\nrefrecative index matched scanning to hydrogel spheres. Hydrogels are water\nbased materials with a low refractive index, which allows for index matching\nwith water-based solvent mixtures. We discuss here various experimental\ntechniques required to handle specifically hydrogel spheres as opposed to other\ntransparent materials. The deformability of hydrogel spheres makes their\nidentification in three dimensional images non-trivial. We will also discuss\nnumerical techniques that can be used in general to detect contacting,\nnon-spherical particles in a three dimensional image. The experimental and\nnumerical techniques presented here give experimental access to the stress\ntensor of a packing of deformed particles."
    },
    {
        "anchor": "Liquid films with high surface modulus moving in tubes: dynamic wetting\n  film and jumpy motion: We investigate the motion through a wet tube of transverse soap films, or\nlamellae, of high surface dilatationnal modulus. Combining local thickness and\nvelocity measurements in the wetting film, we reveal a zone of several\ncentimeters in length, the dynamic wetting film, which is significantly\ninfluenced by a moving lamella. The dependence of this influence length on\nlamella velocity and wetting film thickness provides a discrimination among\nseveral possible surfactant minimal models. A spectacular jumpy mode of\nunsteady motion of a lamella is also evidenced.",
        "positive": "Revealing the hidden dynamics of confined water in acrylate polymers:\n  Insights from hydrogen-bond lifetime analysis: Polymers contain functional groups that participate in hydrogen bond (H-bond)\nwith water molecules, establishing a robust H-bond network that influences bulk\nproperties. This study utilized molecular dynamics (MD) simulations to examine\nthe H-bonding dynamics of water molecules confined within three\npoly(meth)acrylates: poly(2-methoxyethyl acrylate) (PMEA), poly(2-hydroxyethyl\nmethacrylate) (PHEMA), and poly(1-methoxymethyl acrylate) (PMC1A). Results\nshowed that H-bonding dynamics significantly slowed as the water content\ndecreased. Additionally, the diffusion of water molecules and its correlation\nwith H-bond breakage were analyzed. Our findings suggest that when the H-bonds\nbetween water molecules and the methoxy oxygen of PMEA are disrupted, those\nwater molecules persist in close proximity and do not diffuse on a picosecond\ntimescale. In contrast, the water molecules H-bonded with the hydroxy oxygen of\nPHEMA and the methoxy oxygen of PMC1A diffuse concomitantly with the breakage\nof H-bonds. These results provide an in-depth understanding of the impact of\npolymer functional groups on H-bonding dynamics."
    },
    {
        "anchor": "Emergence of tip singularities in dissolution patterns: Chemical erosion, one of the two major erosion processes along with\nmechanical erosion, occurs when a soluble rock like salt, gypsum or limestone\nis dissolved in contact with a water flow. The coupling between the geometry of\nthe rocks, the mass-transfer and the flow leads to the formation of remarkable\npatterns, like scallop patterns in caves. We emphasize the common presence of\nvery sharp shapes and spikes, despite the diversity of hydrodynamic conditions\nand the nature of the soluble materials. We explain the generic emergence of\nsuch spikes in dissolution processes by a geometrical approach. Singularities\nat the interface emerge as a consequence of the erosion directed in the normal\ndirection, when the surface displays curvature variations, like those\nassociated to a dissolution pattern. First, we demonstrate the presence of\nsingular structures in natural interfaces shaped by dissolution. Then, we\npropose simple surface evolution models of increasing complexity demonstrating\nthe emergence of spikes and allowing us to explain at long term by coarsening\nthe formation of cellular structures. Finally, we perform a dissolution pattern\nexperiment driven by solutal convection and we report the emergence of a\ncellular pattern following well the model predictions. Although the precise\nprediction of dissolution shapes necessitates to perform a complete\nhydrodynamic study, we show that the characteristic spikes which are reported\nultimately for dissolution shapes are explained generically by geometrical\narguments due to the surface evolution. These findings can be applied to other\nablation patterns, reported for example in melting ice.",
        "positive": "Macroion correlation effects in electrostatic screening and\n  thermodynamics of highly charged colloids: We study macroion correlation effects on the thermodynamics of highly charged\ncolloidal suspensions using a mean-field theory and primitive model computer\nsimulations. We suggest a simple way to include the macroion correlations into\nthe mean-field theory as an extension of the renormalized jellium model of\nTrizac and Levin [Phys. Rev. E {\\bf 69}, 031403 (2004)]. The effective\nscreening parameters extracted from our mean-field approach are then used in a\none-component model with macroions interacting via Yukawa-like potential to\npredict macroion distributions. We find that inclusion of macroion correlations\nleads to a weaker screening and hence smaller effective macroion charge and\nlower osmotic pressure of the colloidal dispersion as compared to other\nmean-field models. This result is supported by a comparison to primitive model\nsimulations and experiments for charged macroions in the low-salt regime, where\nthe macroion correlations are expected to be significant."
    },
    {
        "anchor": "Energy Spectrum of Vortex Tangle: The energy spectrum of superfluid turbulence in the absence of the normal\nfluid is studied numerically. In order to discuss the statistical properties,\nwe calculated the energy spectra of the 3D velocity field induced by dilute and\ndense vortex tangles respectively, whose dynamics is calculated by the\nBiot-Savart law. In the case of a dense tangle, the slope of the energy\nspectrum is changed at $k=2\\pi/l$, where $l$ is the intervortex spacing. For\n$k>2\\pi/l$, the energy spectrum has $k^{-1}$ behavior in the same manner as the\ndilute vortex tangle, while otherwise the slope of the energy spectrum deviates\nfrom $k^{-1}$ behavior. We compare the behavior for $k<2\\pi/l$ with the\nKolmogorov law.",
        "positive": "Recent developments of surface light scattering as a tool for\n  optical-rheology of polymer monolayers: Surface Quasi-Elastic Light Scattering (SQELS) is an application of dynamic\nlight scattering to measure the dynamics of the thermal roughness of liquid\nsurfaces. An analysis of the spectrum of thermal fluctuations provides\ninformation on surface properties like tension and elasticity. In this work we\nwill focus particularly on its use to study polymer or polymer-like Langmuir\nmonolayers. We review work in this area and give an up-to-date overview of the\nmethod. Important advances have very recently taken place in the theoretical\nunderstanding of this problem, and this has allowed improvements in the\nanalysis of the experimental data. A practical method to estimate the region of\nphysical parameters that can be reliably measured is presented."
    },
    {
        "anchor": "Spherical Vesicles Distorted by a Grafted Latex Bead: An Exact Solution: We present an exact solution to the problem of the global shape description\nof a spherical vesicle distorted by a grafted latex bead. This solution is\nderived by treating the nonlinearity in bending elasticity through the\n(topological) Bogomol'nyi decomposition technique and elastic compatibility. We\nrecover the ``hat-model'' approximation in the limit of a small latex bead and\nfind that the region antipodal to the grafted latex bead flattens. We also\nderive the appropriate shape equation using the variational principle and\nrelevant constraints.",
        "positive": "Cross-linking inhomogeneity in nano-composite hydrogels can be observed\n  as sharp peaks by SAXS experiments under elongation: We introduced silica nanoparticles into poly ($N$,$N$-dimethylacrylamide)\ngel, (PDAM-NC gel), and poly (acrylamide) gel (PAM-NC gel), and carried out\nSAXS measurements under uniaxial elongation. It is well known that PDAM chains\nare strongly adsorbed onto silica nanoparticles while PAM chains are not.\nInterestingly, we found from SAXS measurements that scattering profiles depend\non the polymer-nanoparticle interaction. A four-spot pattern was observed in\nthe 2D structure factors of PDAM-NC gel, which was assigned to a movement of\nthe nanoparticles affinely under elongation. However, unexpectedly, we observed\nsharp peaks in the 2D structure factors of PAM-NC gel in the parallel direction\nto the stretching. These peaks appeared in much lower-$q$ region than the\ntheoretical prediction of affine deformation of nanoparticles. We conjecture\nthat these peaks do not correspond to the correlation of individual particles\nbut to the correlation of high cross-linking regions because the interaction\nbetween PAM chains and silica nanoparticles is relatively weak and the\ndisplacements of silica nanoparticles are sensitive to spatial cross-linking\ninhomogeneity."
    },
    {
        "anchor": "Critical packing in granular shear bands: In a realistic three-dimensional setup, we simulate the slow deformation of\nidealized granular media composed of spheres undergoing an axisymmetric\ntriaxial shear test. We follow the self-organization of the spontaneous strain\nlocalization process leading to a shear band and demonstrate the existence of a\ncritical packing density inside this failure zone. The asymptotic criticality\narising from the dynamic equilibrium of dilation and compaction is found to be\nrestricted to the shear band, while the density outside of it keeps the memory\nof the initial packing. The critical density of the shear band depends on\nfriction (and grain geometry) and in the limit of infinite friction it defines\na specific packing state, namely the \\emph{dynamic random loose packing}.",
        "positive": "Catenoid stability with a free contact line: Contact-drop dispensing is central to many small-scale applications, such as\ndirect-scanning probe lithography and micromachined fountain-pen techniques.\nAccurate and controllable dispensing required for nanometer-resolved surface\npatterning hinges on the stability and breakup of liquid bridges. Here, we\nanalytically study the stability of catenoids pinned at one contact line with\nthe other free to move on a substrate subject to axisymmetric and\nnon-axisymmetric perturbations. We apply a variational formulation to derive\nthe corresponding stability criteria. The maximal stability region and\nstability region are represented in the favourable and canonical phase\ndiagrams, providing a complete description of catenoid equilibrium and\nstability. All catenoids are stable with respect to non-axisymmetric\nperturbations. For a fixed contact angle, there exists a critical volume below\nwhich catenoids are unstable to axisymmetric perturbations. Equilibrium\nsolution multiplicity is discussed in detail, and we elucidate how geometrical\nsymmetry is reflected in the maximal stability and stability regions."
    },
    {
        "anchor": "Dynamical density functional theory with hydrodynamic interactions and\n  colloids in unstable traps: A density functional theory for colloidal dynamics is presented which\nincludes hydrodynamic interactions between the colloidal particles. The theory\nis applied to the dynamics of colloidal particles in an optical trap which\nswitches periodically in time from a stable to unstable confining potential. In\nthe absence of hydrodynamic interactions, the resulting density breathing mode,\nexhibits huge oscillations in the trap center which are almost completely\ndamped by hydrodynamic interactions. The predicted dynamical density fields are\nin good agreement with Brownian dynamics computer simulations.",
        "positive": "Mounding Instability and Incoherent Surface Kinetics: Mounding instability in a conserved growth from vapor is analysed within the\nframework of adatom kinetics on the growing surface. The analysis shows that\ndepending on the local structure on the surface, kinetics of adatoms may vary,\nleading to disjoint regions in the sense of a continuum description. This is\nmanifested particularly under the conditions of instability. Mounds grow on\nthese disjoint regions and their lateral growth is governed by the flux of\nadatoms hopping across the steps in the downward direction. Asymptotically\nln(t) dependence is expected in 1+1- dimensions. Simulation results confirm the\nprediction. Growth in 2+1- dimensions is also discussed."
    },
    {
        "anchor": "Critical adsorption profiles around a sphere and a cylinder in a fluid\n  at criticality: Local functional theory: We study universal critical adsorption on a solid sphere and a solid cylinder\nin a fluid at bulk criticality, where preferential adsorption occurs. We use a\nlocal functional theory proposed by Fisher, de Gennes, and Au-Yang ($[$C. R.\nAcad. Sci. Paris Ser. B {\\bf 287}, 207 (1978)$]$ and $[$Physica {\\bf 101}A, 255\n(1980)$]$). We calculate the mean order parameter profile $\\psi(r)$, where $r$\nis the distance from the sphere center and the cylinder axis, respectively. The\nresultant differential equation for $\\psi(r)$ is solved exactly around a sphere\nand numerically around a cylinder. A strong adsorption regime is realized\nexcept for very small surface field $h_1$, where the surface order parameter\n$\\psi(a)$ is determined by $h_1$ and is independent of the radius $a$. If $r$\nconsiderably exceeds $a$, $\\psi(r)$ decays as $r^{-(1+\\eta)} $ for a sphere and\n$r^{-(1+\\eta)/2} $ for a cylinder in three dimensions, where $\\eta$ is the\ncritical exponent in the order parameter correlation at bulk criticality.",
        "positive": "Critical Casimir effect for colloids close to chemically patterned\n  substrates: Colloids immersed in a critical or near-critical binary liquid mixture and\nclose to a chemically patterned substrate are subject to normal and lateral\ncritical Casimir forces of dominating strength. For a single colloid we\ncalculate these attractive or repulsive forces and the corresponding critical\nCasimir potentials within mean-field theory. Within this approach we also\ndiscuss the quality of the Derjaguin approximation and apply it to Monte Carlo\nsimulation data available for the system under study. We find that the range of\nvalidity of the Derjaguin approximation is rather large and that it fails only\nfor surface structures which are very small compared to the geometric mean of\nthe size of the colloid and its distance from the substrate. For certain\nchemical structures of the substrate the critical Casimir force acting on the\ncolloid can change sign as a function of the distance between the particle and\nthe substrate; this provides a mechanism for stable levitation at a certain\ndistance which can be strongly tuned by temperature, i.e., with a sensitivity\nof more than 200nm/K."
    },
    {
        "anchor": "Azimuthal instability of the radial thermocapillary flow around a hot\n  bead trapped at the water-air interface: We investigate the radial thermocapillary flow driven by a laser-heated\nmicrobead in partial wetting at the water-air interface. Particular attention\nis paid to the evolution of the convective flow patterns surrounding the hot\nsphere as the latter is increasingly heated. The flow morphology is nearly\naxisymmetric at low laser power P. Increasing P leads to symmetry breaking with\nthe onset of counter-rotating vortex pairs. The boundary condition at the\ninterface, close to no-slip in the low-P regime, turns about stress-free\nbetween the vortex pairs in the high-P regime. These observations strongly\nsupport the view that surface-active impurities are inevitably adsorbed on the\nwater surface where they form an elastic layer. The onset of vortex pairs is\nthe signature of a hydrodynamic instability in the layer response to the\ncentrifugal forced flow. Interestingly, our study paves the way for the design\nof active colloids able to achieve high-speed self-propulsion via vortex pair\ngeneration at a liquid interface.",
        "positive": "From depinning transition to plastic yielding of amorphous media: A soft\n  modes perspective: A mesoscopic model of amorphous plasticity is discussed in the context of\ndepinning models. After embedding in a d + 1 dimensional space, where the\naccumulated plastic strain lives along the additional dimension, the gradual\nplastic deformation of amorphous media can be regarded as the motion of an\nelastic manifold in a disordered landscape. While the associated depinning\ntransition leads to scaling properties, the quadrupolar Eshelby interactions at\nplay in amorphous plasticity induce specific additional features like\nshear-banding and weak ergodicity breakdown. The latters are shown to be\ncontrolled by the existence of soft modes of the elastic interaction, the\nconsequence of which is discussed in the context of depinning."
    },
    {
        "anchor": "The Physics of Life: No such thing as a dumb question: Physics of Life research in the UK is proving to be transformative to\nscientific insight and translational impact, but challenges remain. Here I\ndiscuss its disruptive potential and the barriers to interdisciplinary research\nseen through the lens of the activities of one of its pioneers, Tom McLeish,\nFRS.",
        "positive": "Like-Charge Colloid-Polyelectrolyte Complexation: We investigate the complexation of a highly charged sphere with a long\nflexible polyelectrolyte, \\textit{both negatively charged} in salt free\nenvironment. Electroneutrality is insured by the presence of divalent\ncounterions. Using molecular dynamics (MD) within the framework of the\nprimitive model, we consider different Coulomb coupling regimes. At strong\nCoulomb coupling we find that the adsorbed chain is always confined to the\ncolloidal surface but forms different conformations that depend on the linear\ncharge density of the chain. A mechanism involving the polyelectrolyte\n\\textit{overcharging} is proposed to explain these structures. At intermediate\nCoulomb coupling, the chain conformation starts to become three-dimensional,\nand we observe multilayering of the highly charged chain while for lower charge\ndensity the chain wraps around the colloid. At weak Coulomb coupling,\ncorresponding to an aqueous solvent, we still find like-charge complexation. In\nthis latter case the chain conformation exhibits loops."
    },
    {
        "anchor": "Floating flocks: Two-dimensional long-range uniaxial order in\n  three-dimensional active fluids: Elongated active units cannot spontaneously break rotation symmetry in bulk\nfluids to form nematic or polar phases. This has led to the image of active\nsuspensions as spontaneously evolving, spatiotemporally chaotic fluids. In\ncontrast, I show that bulk active fluids have stable active nematic and polar\nstates at fluid-fluid or fluid-air interfaces. The active flow-mediated\nlong-range interactions that destroy the ordered phase in bulk, lead to\nlong-range order at the interface. The active fluids have a surface ordering\ntransition and form states with quiescent, ordered surfaces and a chaotic bulk.\nI further consider active units that are constrained to live at an interface to\nexamine the minimal conditions for the existence of two-dimensional order in\nbulk three-dimensional fluids. In this case, immotile units do not order, but\nmotile particles still form a long-range-ordered polar phase. This prediction\nof stable, uniaxial, active phases in bulk fluids may have functional\nconsequences for active transport.",
        "positive": "Line and Point Defects in Nonlinear Anisotropic Solids: In this paper, we present some analytical solutions for the stress fields of\nnonlinear anisotropic solids with distributed line and point defects. In\nparticular, we determine the stress fields of i) a parallel\ncylindrically-symmetric distribution of screw dislocations in infinite\northotropic and monoclinic media, ii) a cylindrically-symmetric distribution of\nparallel wedge disclinations in an infinite orthotropic medium, iii) a\ndistribution of edge dislocations in an orthotropic medium, and iv) a\nspherically-symmetric distribution of point defects in a transversely isotropic\nspherical ball."
    },
    {
        "anchor": "The Effect of Air on Granular Size Separation in a Vibrated Granular Bed: Using high-speed video and magnetic resonance imaging (MRI) we study the\nmotion of a large sphere in a vertically vibrated bed of smaller grains. As\npreviously reported we find a non-monotonic density dependence of the rise and\nsink time of the large sphere. We find that this density dependence is solely\ndue to air drag. We investigate in detail how the motion of the intruder sphere\nis influenced by size of the background particles, initial vertical position in\nthe bed, ambient pressure and convection. We explain our results in the\nframework of a simple model and find quantitative agreement in key aspects with\nnumerical simulations to the model equations.",
        "positive": "Fabrication of robust capsules by sequential assembly of\n  polyelectrolytes onto charged liposomes: This work presents a simply methodology for coating small unilamellar\nliposomes bearing different degrees of positive charge with polyelectrolyte\nmultilayers using the sequential Layer-by-Layer (LbL) deposition method. The\nliposomes were made of mixtures of DOPC\n(1,2-dioleyl-sn-glycero-3-phosphocoline) and DODAB (dimethyl dioctadecyl\nammonium bromide), and coated by alternated layers of the sodium salt of\npoly(4-styrenesulfonate), PSS, and poly(allylamine), PAH, as polyanion and\npolycations, respectively. The results shows that the zeta potential of the\nliposomes was not very sensitive to the mole fraction of DODAB in the membrane,\nXD, in the range 0.3< XD<0.8. We were able to coat the liposomes with up to\nfour polymer bilayers. The growth of the capsules size was followed by dynamic\nlight scattering, and in some cases by cryo-TEM, with good agreement between\nboth techniques. The thickness of the layers, measured from the hydrodynamic\nradius of the coated liposome, depends on the polyelectrolyte used, so that the\nPSS layers adopt a much more packaged conformation than the PAH layers. An\ninteresting finding is that the PSS amount needed to reach the isoelectric\npoint of the capsules increases linearly with the charge density of the bare\nliposomes, whereas the amount of PAH does not depend on it. As expected, the\npreparation of the multilayers has to be done in such a way that when the\nsystem is close to the isoelectric point the capsules do not aggregate. For\nthis, we dropped the polyelectrolyte solution quickly, fast stirring and using\ndilute liposome suspensions. The method is very flexible and not limited to\nliposomes or polyelectrolyte multilayers, also coatings containing charged\nnanoparticles can be easily made."
    },
    {
        "anchor": "Theorem for the design of deployable kirigami tessellations with\n  different topologies: The concept of kirigami has been extensively utilized to design deployable\nstructures and reconfigurable metamaterials. Despite heuristic utilization of\nclassical kirigami patterns, the gap between complex kirigami tessellations and\nsystematic design principles still needs to be filled. In this paper, we\ndevelop a unified design method for deployable quadrilateral kirigami\ntessellations perforated on flat sheets with different topologies. This method\nis based on the parametrization of kirigami patterns formulated as the solution\nof a linear equation system. The geometric constraints for the deployability of\nparametrized cutting patterns are given by a unified theorem covering different\ntopologies of the flat sheets. As an application, we employ the design method\nto achieve desired shapes along the deployment path of kirigami tessellations,\nwhile preserving the topological characteristics of the flat sheets. Our\napproach introduces interesting perspectives for the topological design of\nkirigami-inspired structures and metamaterials.",
        "positive": "Force distributions near the jamming and glass transitions: We calculate the distribution of interparticle normal forces $P(F)$ near the\nglass and jamming transitions in model supercooled liquids and foams,\nrespectively. $P(F)$ develops a peak that appears near the glass or jamming\ntransitions, whose height increases with decreasing temperature, decreasing\nshear stress and increasing packing density. A similar shape of $P(F)$ was\nobserved in experiments on static granular packings. We propose that the\nappearance of this peak signals the development of a yield stress. The\nsensitivity of the peak to temperature, shear stress and density lends credence\nto the recently proposed generalized jamming phase diagram."
    },
    {
        "anchor": "Structure formation in monolayers composed of hard bent-core molecules: Two-dimensional ensembles of bent-core shaped molecules attain at highly\norienting surfaces liquid crystalline structures characteristic mostly for\nlamellar chiral or nonchiral antiferroelectric order. Here, using the\nOnsager-type of density functional theory supplemented by constant-pressure\nMonte-Carlo (MC) simulation we investigate the role of excluded-volume\ninteractions in stabilizing different structures in monolayers filled with\nbent-shaped molecules. We study influence of molecular features, like the apex\nangle, thickness of the arm and the type of the arm edges on the stability of\nlayered structures. For simple molecular shapes taken the observed phases are\ndominated by the lamellar antiferroelectric type as observed experimentally,\nbut a considerable sensitivity of the ordering to details of the molecular\nshape is found for order parameters and wave vectors of the structures.\nInterestingly, for large opening angles and not too thick molecules a window of\nstable nematic splay-bend phase is shown to exist. The presented theory models\nequilibrium properties of bent-core liquid crystals subjected to strong planar\nanchoring, in the case when details of the surface are of secondary importance.",
        "positive": "Effective charge, collapse and the critical point of a polyelectrolyte\n  chain: The charge of a polyelectrolyte (PE) controls myriads of phenomena in\nbiology, biotechnology, and materials science, but still remains elusive from\nan understanding. Considering the adsorption of counterions on an isolated PE\nchain, an analytical expression for the effective charge - valid for all chain\nflexibility, for variable salt, in good solvents at all conditions, in poor\nsolvents in the expanded (coil) state away from the critical point, and for\ngels, brushes and other PE systems in their expanded state - is derived. Phase\nboundaries and the critical point for the I-st order collapse transition,\ninduced cooperatively by counterion adsorption and chain conformations, are\ncalculated self-consistently. The size of the PE chain is found to be a\nsingle-valued function of charge."
    },
    {
        "anchor": "A computationally efficacious free-energy functional for studies of\n  inhomogeneous liquid water: We present an accurate equation of state for water based on a simple\nmicroscopic Hamiltonian, with only four parameters that are well-constrained by\nbulk experimental data. With one additional parameter for the range of\ninteraction, this model yields a computationally efficient free-energy\nfunctional for inhomogeneous water which captures short-ranged correlations,\ncavitation energies and, with suitable long-range corrections, the non-linear\ndielectric response of water, making it an excellent candidate for studies of\nmesoscale water and for use in ab initio solvation methods.",
        "positive": "Time Scales of Fickian Diffusion and the Lifetime of Dynamic\n  Heterogeneity: Dynamic heterogeneity, believed to be one of the hallmarks of the dynamics of\nsupercooled liquids, is expected to affect the diffusion of the particles\ncomprising the liquid. We have carried out extensive molecular dynamics\nsimulations of two model glass-forming liquids in three dimensions to study the\ntime scales at which Fick's law of diffusion starts to set in. We have\nidentified two different Fickian timescales: one at which the mean squared\ndisplacement begins to show a linear dependence on time, and another one at\nwhich the distribution of particle displacements becomes Gaussian. These two\ntimes scales are found to be very different from each other and from the\n$\\alpha$ relaxation time in both systems. An interesting connection is found\nbetween one of these Fickian time scales and the time scale obtained from the\nbond-breakage correlation function. We discuss the relationships between these\ndifferent timescales and their connection to dynamic heterogeneity in the\nsystem."
    },
    {
        "anchor": "Dynamic Properties of Molecular Motors in Burnt-Bridge Models: Dynamic properties of molecular motors that fuel their motion by actively\ninteracting with underlying molecular tracks are studied theoretically via\ndiscrete-state stochastic ``burnt-bridge'' models. The transport of the\nparticles is viewed as an effective diffusion along one-dimensional lattices\nwith periodically distributed weak links. When an unbiased random walker passes\nthe weak link it can be destroyed (``burned'') with probability p, providing a\nbias in the motion of the molecular motor. A new theoretical approach that\nallows one to calculate exactly all dynamic properties of motor proteins, such\nas velocity and dispersion, at general conditions is presented. It is found\nthat dispersion is a decreasing function of the concentration of bridges, while\nthe dependence of dispersion on the burning probability is more complex. Our\ncalculations also show a gap in dispersion for very low concentrations of weak\nlinks which indicates a dynamic phase transition between unbiased and biased\ndiffusion regimes. Theoretical findings are supported by Monte Carlo computer\nsimulations.",
        "positive": "Chemotactic and hydrodynamic effects on collective dynamics of\n  self-diffusiophoretic Janus motors: Collective motion in nonequilibrium steady state suspensions of\nself-propelled Janus motors driven by chemical reactions can arise due to\ninteractions coming from direct intermolecular forces, hydrodynamic flow\neffects, or chemotactic effects mediated by chemical gradients. The relative\nimportance of these interactions depends on the reactive characteristics of the\nmotors, the way in which the system is maintained in a steady state, and\nproperties of the suspension, such as the volume fraction. From simulations of\na microscopic hard collision model for the interaction of fluid particles with\nthe Janus motor we show that dynamic cluster states exist and determine the\ninteraction mechanisms that are responsible for their formation. The relative\nimportance of chemotactic and hydrodynamic effects is identified by considering\na microscopic model in which chemotactic effects are turned off while the full\nhydrodynamic interactions are retained. The system is maintained in a steady\nstate by means of a bulk reaction in which product particles are reconverted\ninto fuel particles. The influence of the bulk reaction rate on the collective\ndynamics is also studied."
    },
    {
        "anchor": "Colloidal interactions in two dimensional nematics: The interaction between two disks immersed in a 2D nematic is investigated\n(i) analitically using the tensor order parameter formalism for the nematic\nconfiguration around isolated disks and (ii) numerically using finite element\nmethods with adaptive meshing to minimize the corresponding Landau-de Gennes\nfree energy. For strong homeotropic anchoring, each disk generates a pair of\ndefects with one-half topological charge responsible for the 2D quadrupolar\ninteraction between the disks at large distances. At short distance, the\nposition of the defects may change, leading to unexpected complex interactions\nwith the quadrupolar repulsive interactions becoming attractive. This short\nrange attraction in all directions is still anisotropic. As the distance\nbetween the disks decreases their preferred relative orientation with respect\nto the far-field nematic director changes from oblique to perpendicular.",
        "positive": "A biological tissue-inspired tunable photonic fluid: Inspired by how cells pack in dense biological tissues, we design 2D and 3D\namorphous materials which possess a complete photonic band gap. A physical\nparameter based on how cells adhere with one another and regulate their shapes\ncan continuously tune the photonic band gap size as well as the bulk mechanical\nproperties of the material. The material can be tuned to go through a\nsolid-fluid phase transition characterized by a vanishing shear modulus.\nRemarkably, the photonic band gap persists in the fluid phase, giving rise to a\nphotonic fluid that is robust to flow and rearrangements. Experimentally this\ndesign should lead to the engineering of self-assembled non-rigid photonic\nstructures with photonic band gaps that can be controlled in real time via\nmechanical and thermal tuning."
    },
    {
        "anchor": "Phantom-Chain Simulations for the Effect of Node Functionality on the\n  Fracture of Star-Polymer Networks: The influence of node functionality (f) on the fracture of polymer networks\nremains unclear. While many studies have focused on multi-functional nodes with\nf>4, recent research suggests that networks with f=3 exhibit superior fracture\nproperties compared to those with f=4. To clarify this discrepancy, we\nconducted phantom chain simulations for star-polymer networks varying f between\n3 and 8. Our simulations utilized equimolar binary mixtures of star branch\nprepolymers with a uniform arm length. We employed a Brownian dynamics scheme\nto equilibrate sols and induce gelation through end-linking reactions. We\nprevented the formation of odd-order loops owing to the binary reaction and\nsecond-order loops algorithmically. We stored network structures at various\nconversion ratios ({\\phi}_c) and minimized energy to reduce computation costs\ninduced by structural relaxation. We subjected the networks to stretching until\nfracture to determine stress and strain at break and work for fracture,\n{\\epsilon}_b, {\\sigma}_b, and W_b. These fracture characteristics are highly\ndependent on {\\phi}_c for networks with small f but relatively insensitive for\nthose with large f. Thus, the networks with small f exhibit greater fracture\nproperties than those with large f at high {\\phi}_c, whereas the opposite\nrelationship occurs at low {\\phi}_c. We analyzed {\\epsilon}_b, {\\sigma}_b, and\nW_b concerning the cycle rank {\\xi} and the broken strand fraction {\\phi}_bb.\nWe found {\\epsilon}_b, {\\sigma}_b/{\\phi}_bb, and W_b/{\\phi}_bb monotonically\ndecrease with increasing {\\xi}, and the data for various f and {\\phi}_c\nsuperpose with each other to draw master curves. These results imply that the\nmechanical superiority of the networks with small f comes from their smaller\n{\\xi} that gives higher {\\epsilon}_b, {\\sigma}_b/{\\phi}_bb, and W_b/{\\phi}_bb\nthan the networks with large f.",
        "positive": "Principles of thermal design with nematic liquid crystals: Highly engineered materials are arousing great interest because of their\nability to manipulate heat, as described by coordinate transformation approach.\nBased on the recently developed analog gravity models, this paper presents how\na simple device based on nematic liquid crystal can achieve in principle either\nthermal concentration or expulsion. These outcomings are shown to stem from\ntopological properties of a disclination-like structure, induced in the nematic\nby anchoring conditions."
    },
    {
        "anchor": "Zipping mechanism for force-generation by growing filament bundles: We investigate the force generation by polymerizing bundles of filaments,\nwhich form because of short-range attractive filament interactions. We show\nthat bundles can generate forces by a zipping mechanism, which is not limited\nby buckling and operates in the fully buckled state. The critical zipping\nforce, i.e. the maximal force that a bundle can generate, is given by the\nadhesive energy gained during bundle formation. For opposing forces larger than\nthe critical zipping force, bundles undergo a force-induced unbinding\ntransition. For larger bundles, the critical zipping force depends on the\ninitial configuration of the bundles. Our results are corroborated by Monte\nCarlo simulations.",
        "positive": "Sequence Effects on DNA Entropic Elasticity: DNA stretching experiments are usually interpreted using the worm-like chain\nmodel; the persistence length A appearing in the model is then interpreted as\nthe elastic stiffness of the double helix. In fact the persistence length\nobtained by this method is a combination of bend stiffness and intrinsic bend\neffects reflecting sequence information, just as at zero stretching force. This\nobservation resolves the discrepancy between the value of A measured in these\nexperiments and the larger ``dynamic persistence length'' measured by other\nmeans. On the other hand, the twist persistence length deduced from\ntorsionally-constrained stretching experiments suffers no such correction. Our\ncalculation is very simple and analytic; it applies to DNA and other polymers\nwith weak intrinsic disorder."
    },
    {
        "anchor": "Surface charge and hydrodynamic coefficient measurements of {\\it\n  Bacillus subtilis} spore by Optical Tweezers: In this work we report on the simultaneous measurement of the hydrodynamic\ncoefficient and the electric charge of single {\\it Bacillus subtilis} spores.\nThe latter has great importance in protein binding to spores and in the\nadhesion of spores onto surfaces. The charge and the hydrodynamic coefficient\nwere measured by an accurate procedure based on the analysis of the motion of\nsingle spores confined by an optical trap. The technique has been validated\nusing charged spherical polystyrene beads. The excellent agreement of our\nresults with the expected values demonstrates the quality of our procedure. We\nmeasured the charge of spores of {\\it B. subtilis} purified from a wild type\nstrain and from two isogenic mutants characterized by an altered spore surface.\nOur technique is able to discriminate the three spore types used, by their\ncharge and by their hydrodynamic coefficient which is related to the\nhydrophobic properties of the spore surface.",
        "positive": "A topologically-protected interior for three-dimensional confluent\n  cellular collectives: Organoids are in vitro cellular collectives from which brain-like, or\ngut-like, or kidney-like structures emerge. To make quantitative predictions\nregarding the morphology and rheology of a cellular collective in its initial\nstages of development, we construct and study a three-dimensional vertex model.\nIn such a model, the cells are represented as deformable polyhedrons with cells\nsharing faces such that there are no gaps between them, otherwise known as\nconfluent. In a bulk model with periodic boundary conditions, we find a\nrigidity transition as a function of the target cell shape index $s_0$ with a\ncritical value $s_0^*=5.39\\pm0.01$. For a confluent cellular collective with a\nfinite boundary, and in the presence of lateral extensile and in-plane, radial\nextensile deformations, we find a significant boundary-bulk effect that is\none-cell layer thick. More specifically, for lateral extensile deformations,\nthe cells in the bulk are much less aligned with the direction of the lateral\ndeformation than the cells at the boundary. For in-plane, radial deformations,\nthe cells in the bulk exhibit much less reorientation perpendicular to the\nradial direction than the cells at the boundary. In other words, for both\ndeformations, the bulk, interior cells are topologically-protected from the\ndeformations, at least over time scales much slower than the timescale for\ncellular rearrangements and up to reasonable amounts of strain. Our results\nprovide an underlying mechanism for some observed cell shape patterning in\norganoids. Finally, we discuss the use of a cellular-based approach to\ndesigning organoids with new types of morphologies to study the intricate\nrelationship between structure and function at the multi-cellular scale for\nexample."
    },
    {
        "anchor": "Contact mechanics for randomly rough surfaces: When two solids are squeezed together they will in general not make atomic\ncontact everywhere within the nominal (or apparent) contact area. This fact has\nhuge practical implications and must be considered in many technological\napplications. In this paper I briefly review basic theories of contact\nmechanics. I consider in detail a recently developed contact mechanics theory.\nI derive boundary conditions for the stress probability distribution function\nfor elastic, elastoplastic and adhesive contact between solids and present\nnumerical results illustrating some aspects of the theory. I analyze contact\nproblems for very smooth polymer (PMMA) and Pyrex glass surfaces prepared by\ncooling liquids of glassy materials from above the glass transition\ntemperature. I show that the surface roughness which results from the frozen\ncapillary waves can have a large influence on the contact between the solids.\nThe analysis suggest a new explanation for puzzling experimental results [L.\nBureau, T. Baumberger and C. Caroli, arXiv:cond-mat/0510232] about the\ndependence of the frictional shear stress on the load for contact between a\nglassy polymer lens and flat substrates. I discuss the possibility of testing\nthe theory using numerical methods, e.g., finite element calculations.",
        "positive": "Relaxation Scenarios in a Mixture of Large and Small Spheres: Dependence\n  on the Size Disparity: We present a computational investigation on the slow dynamics of a mixture of\nlarge and small soft spheres. By varying the size disparity at a moderate fixed\ncomposition different relaxation scenarios are observed for the small\nparticles. For small disparity density-density correlators exhibit moderate\nstretching. Only small quantitative differences are observed between dynamic\nfeatures for large and small particles. On the contrary, large disparity\ninduces a clear time scale separation between the large and the small\nparticles. Density-density correlators for the small particles become extremely\nstretched, and display logarithmic relaxation by properly tuning the\ntemperature or the wavevector. Self-correlators decay much faster than\ndensity-density correlators. For very large size disparity, a complete\nseparation between self- and collective dynamics is observed for the small\nparticles. Self-correlators decay to zero at temperatures where density-density\ncorrelations are frozen. The dynamic picture obtained by varying the size\ndisparity resembles features associated to Mode Coupling transition lines of\nthe types B and A at, respectively, small and very large size disparity. Both\nlines might merge, at some intermediate disparity, at a higher-order point, to\nwhich logarithmic relaxation would be associated. This picture resembles\npredictions of a recent Mode Coupling Theory for fluids confined in matrixes\nwith interconnected voids [V. Krakoviack, Phys. Rev. Lett. {\\bf 94}, 065703\n(2005)]."
    },
    {
        "anchor": "Colloidal spirals in nematic liquid crystals: One of the central experimental efforts in nematic colloids research aims to\nexplore how the interplay between the geometry of particles along with the\naccompanying nematic director deformations and defects around them can provide\na means of guiding particle self-assembly and controlling the structure of\nparticle-induced defects. In this work, we design, fabricate, and disperse\nlow-symmetry colloidal particles with shapes of spirals, double spirals, and\ntriple spirals in a nematic fluid. These spiral-shaped particles, which are\ncontrolled by varying their surface functionalization to provide tangential or\nperpendicular boundary conditions of the nematic molecular alignment, are found\ninducing director distortions and defect configurations with non-chiral or\nchiral symmetry. Colloidal particles also exhibit both stable and metastable\nmultiple orientational states in the nematic host, with a large number of\ndirector configurations featuring both singular and solitonic nonsingular\ntopological defects accompanying them, which can result in unusual forms of\ncolloidal self-assembly. Our findings directly demonstrate how the symmetry of\nparticle-generated director configurations can be further lowered, or not, as\ncompared to the low point group symmetry of solid micro-inclusions, depending\non the nature of induced defects while satisfying topological constraints. We\nshow that achiral colloidal particles can cause chiral symmetry breaking of\nelastic distortions, which is driven by complex three-dimensional winding of\ninduced topological line defects and solitons.",
        "positive": "Effect of cytosol viscosity on the flow behavior of red blood cell\n  suspensions in microvessels: The flow behavior of blood in microvessels is directly associated with tissue\nperfusion and oxygen delivery. Current efforts on modeling blood flow have\nprimarily focused on the flow properties of blood with red blood cells (RBCs)\nhaving a viscosity ratio $C$ of unity between the cytosol and suspending\nmedium, while under physiological conditions the cytosol viscosity is about\nfive times larger than the plasma viscosity (i.e., $C\\approx 5$). The\nimportance of $C$ for the behavior of single RBCs in fluid flow has already\nbeen demonstrated, while the effect of $C$ on blood flow has only been sparsely\nstudied. We employ mesoscopic hydrodynamic simulations to perform a systematic\ninvestigation of flow properties of RBC suspensions with different cytosol\nviscosities for various flow conditions in cylindrical microchannels. Our main\naim is to link macroscopic flow properties such as flow resistance to single\ncell deformation and dynamics as a function of $C$. Starting from a dispersed\ncell configuration, we find that the flow convergence and the development of a\nRBC-free layer (RBC-FL) depend only weakly on $C$, and require a convergence\nlength in the range of $25D-50D$, where $D$ is the channel diameter. The flow\nresistance for $C=5$ is nearly the same as that for $C=1$, which is facilitated\nby a slightly larger RBC-FL thickness for $C=5$. This effect is due to the\nsuppression of membrane motion and dynamic shape deformations by a more viscous\ncytosol for $C=5$, resulting in a more compact cellular core of the flow in\ncomparison to $C=1$. The weak effect of cytosol viscosity on the flow\nresistance and RBC-FL explains why cells can have a high concentration of\nhemoglobin for efficient oxygen delivery, without a pronounced increase in the\nflow resistance."
    },
    {
        "anchor": "Surface Nucleation in the Freezing of Gold Nanoparticles: We use molecular simulation to calculate the nucleation free energy barrier\nfor the freezing of a 456 atom gold cluster over a range of temperatures. The\nresults show that the embryo of the solid cluster grows at the vapor-surface\ninterface for all temperatures studied and that the usual classical nucleation\nmodel, with the embryo growing in the core of the cluster, is unable to predict\nthe shape of the free energy barrier. We use a simple partial wetting model\nthat treats the crystal as a lens shaped nucleus at the liquid-vapor interface\nand find that the line tension plays an important role in the freezing of gold\nnanoparticles.",
        "positive": "Long-wavelength fluctuations and static correlations in quasi-2D\n  colloidal suspensions: Dimensionality strongly affects thermal fluctuations and critical dynamics of\nequilibrium systems. These influences persist in amorphous systems going\nthrough the nonequilibrium glass transition. Here, we experimentally study the\nglass transition of quasi-2D suspensions of spherical and ellipsoidal particles\nunder different degrees of circular confinement. We show that the strength of\nthe long-wavelength fluctuations increases logarithmically with system sizes\nand displays the signature of the Mermin-Wagner fluctuations. Moreover, using\nconfinement as a tool, we also measure static structural correlations and\nextract a growing static correlation length in 2D supercooled liquids. Finally,\nwe explore the influence of the Mermin-Wagner fluctuations on the translational\nand orientational relaxations of 2D ellipsoidal suspensions, which leads to a\nnew interpretation of the two-step glass transition and the orientational glass\nphase of anisotropic particles. Our study reveals the importance of\nlong-wavelength fluctuations in 2D supercooled liquids and provides new\ninsights into the role of dimensionality in the glass transition."
    },
    {
        "anchor": "Vibration can enhance stick-slip behavior for granular friction: We experimentally study the frictional behavior of a two-dimensional slider\npulled slowly over a granular substrate comprised of photoelastic disks. The\nslider is vibrated at frequencies ranging from 0 to 30 Hz in a direction\nparallel to sliding. The applied vibrations have constant peak acceleration,\nwhich results in constant average friction levels. Surprisingly, we find that\nstick-slip behavior, where stress slowly builds up and is released in\nintermittent slips, is enhanced as the frequency of vibration is increased. Our\nresults suggest that increasing the frequency of vibration may help to combine\nmany smaller rearrangements into fewer, but larger, avalanche-like slips, a\nmechanism unique to granular systems. We also examine the manner in which the\nself affine character of the force curves evolves with frequency, and we find\nadditional support for this interpretation.",
        "positive": "On/off switching of adhesion in gecko-inspired adhesives: In this study, the adhesion-detachment behaviour of a gecko-inspired adhesive\npad was investigated to understand the on/off switching mechanisms of adhesion\nin gecko feet. A macroscopic spatula model was fabricated using silicone\nrubber, and adhesion tests combining lateral sliding and vertical debonding\nwere conducted. It was observed that the contact state and the adhesion force\nof the pad vary considerably with the direction of lateral sliding prior to\ndebonding, and that the pad achieves adhesion during debonding even when it\nloses contact due to excess lateral sliding. These results explain the\nmechanisms behind the on/off switching and stable adhesion of gecko feet, and\nsuggest the possibility of developing new-generation adhesives capable of\nswitchable adhesion."
    },
    {
        "anchor": "X-ray Near Field Speckle: Implementation and Critical Analysis: We have implemented the newly-introduced, coherence-based technique of x-ray\nnear-field speckle (XNFS) at 8-ID-I at the Advanced Photon Source. In the near\nfield regime of high-brilliance synchrotron x-rays scattered from a sample of\ninterest, it turns out, that, when the scattered radiation and the main beam\nboth impinge upon an x-ray area detector, the measured intensity shows\nlow-contrast speckles, resulting from interference between the incident and\nscattered beams. We built a micrometer-resolution XNFS detector with a high\nnumerical aperture microscope objective and demonstrate its capability for\nstudying static structures and dynamics at longer length scales than\ntraditional far field x-ray scattering techniques. Specifically, we\ncharacterized the structure and dynamics of dilute silica and polystyrene\ncolloidal samples. Our study reveals certain limitations of the XNFS technique,\nwhich we discuss.",
        "positive": "Apollonian Packing in Polydisperse Emulsions: We have discovered the existence of polydisperse High Internal-Phase-Ratio\nEmulsions (HIPE) in which the internal-phase droplets, present at 95% volume\nfraction, remain spherical and organize themselves in the available space\naccording to Apollonian packing rules. These polydisperse HIPE are formed\nduring emulsification of surfactant-poor compositions of oil-surfactant-water\ntwo-phase systems. Their droplet size-distributions evolve spontaneously\ntowards power laws with the Apollonian exponent. Small-Angle X-Ray Scattering\nperformed on aged HIPEs demonstrated that the droplet packing structure\ncoincided with that of a numerically simulated Random Apollonian Packing. We\nargue that these peculiar, space-filling assemblies are a result of coalescence\nand fragmentation processes obeying simple geometrical rules of conserving\ntotal volume and minimizing surface area."
    },
    {
        "anchor": "Accelerated Formation of H2 Nanobubbles from a Surface Nanodroplet\n  Reaction: The compartmentalization of chemical reactions within droplets has advantages\nin low costs, reduced consumption of reagents and increased throughput.\nReactions in small droplets have also been shown to greatly accelerate the rate\nof many chemical reactions. The accelerated growth rate of nanobubbles from\nnanodroplet reactions is demonstrated in this work. The gaseous products from\nthe reaction at the nanodroplet surface promoted nucleation of hydrogen\nnanobubbles within multiple organic liquid nanodroplets. The nanobubbles were\nconfined within the droplets and selectively grew and collapsed at the droplet\nperimeter, as visualized by microscopy with high spatial and temporal\nresolutions. The growth rate of the bubbles was significantly accelerated\nwithin small droplets and scaled inversely with droplet radius. The\nacceleration was attributed to confinement from the droplet volume and effect\nfrom the surface area on the interfacial chemical reaction for gas production.\nThe results of this study provide further understanding for applications in\ndroplet enhanced production of nanobubbles and the on-demand liberation of\nhydrogen.",
        "positive": "Pressure, surface tension and curvature in active systems: A touch of\n  equilibrium: We explore the pressure of active particles on curved surfaces and its\nrelation to other interfacial properties. We use both direct simulations of the\nactive systems as well as simulations of an equilibrium system with effective\n(pair) interactions designed to capture the effects of activity. Comparing the\nactive and effective passive systems in terms of their bulk pressure, we\nelaborate that the most useful theoretical route to this quantity is via the\ndensity profile at a flat wall. This is corroborated by extending the study to\ncurved surfaces and establishing a connection to the particle adsorption and\nintegrated surface excess pressure (surface tension). In the ideal-gas limit,\nthe effect of curvature on the mechanical properties can be calculated\nanalytically in the passive system with effective interactions, and shows good\n(but not exact) agreement with simulations of the active models. It turns out\nthat even the linear correction to the pressure is model specific and equals\nthe planar adsorption in each case, which means that a known equilibrium sum\nrule can be extended to a regime at small but nonzero activity. In turn, the\nrelation between the planar adsorption and the surface tension is reminiscent\nof the Gibbs adsorption theorem at an effective temperature. At finite\ndensities, where particle interactions play a role, the presented\neffective-potential approximation captures the effect of density on the\ndependence of the pressure on curvature."
    },
    {
        "anchor": "Jamming on deformable surfaces: Jamming is a fundamental transition that governs the mechanical behavior of\nparticulate media, including sand, foam and dense suspensions but also\nbiological tissues: Upon compression, particulate media can change from freely\nflowing to a disordered solid. Jamming has previously been conceived as a bulk\nphenomenon involving particle motions in fixed geometries. In a diverse class\nof soft materials, however, solidification can take place in a deformable\ngeometry, such as on the surface of a fluid droplet or in the formation of a\nbijel. In these systems the nature and dynamics of jamming remains unknown.\nHere we propose and study a scenario we call metric jamming that aims to\ncapture the complex interactions between shape and particles. Unlike classical\njamming processes that exhibit discrete mechanical transitions, surprisingly we\nfind that metric jammed states possess mechanical properties that are\ncontinuously tunable between those of classical jammed and conventional elastic\nmedia. New types of vibrational mode that couple particulate and surface\ndegrees of freedom are also observed. Our work lays the groundwork for a\nunified understanding of jamming in deformable geometries, to exploit jamming\nfor the control and stabilization of shape in self-assembly processes, and\nprovides new tools to interrogate solidification processes in deformable media\nmore generally.",
        "positive": "Aggregation of rod-like polyelectrolyte chains in the presence of\n  monovalent counterions: Using molecular dynamics simulations, it is demonstrated that monovalent\ncounterions can induce aggregation of similarly charged rod-like\npolyelectrolyte chains. The critical value of the linear charge density for\naggregation is shown to be close to the critical value for the\nextended-collapsed transition of a single flexible polyelectrolyte chain, and\ndecreases with increasing valency of the counterions. The effective interaction\npotential between two rod-like polyelectrolyte chains is measured, and is\nrelated to the angular distribution of the condensed counterions."
    },
    {
        "anchor": "Oscillating vector solitary waves in soft laminates: Vector solitary waves are nonlinear waves of coupled polarizations that\npropagate with constant velocity and shape. In mechanics, they hold the\npotential to control locomotion, mitigate shocks and transfer information,\namong other functionalities. Recently, such elastic waves were numerically\nobserved in compressible rubber-like laminates. Here, we conduct numerical\nexperiments to characterize the possible vector solitary waves in these\nlaminates, and expose a new type of waves whose amplitude and velocity\noscillate periodically without dispersing in time. This oscillation is a\nmanifestation of a periodic transfer of energy between the two wave\npolarizations, which we consider as internal mode of the solitary wave. We find\nthat the vector solitary waves propagate faster at higher amplitudes, and\ndetermine a lower bound for their velocity. We describe a procedure for\nidentifying which initial strains generate such vector solitary waves. This\nprocedure also enables an additional classification between tensile and\ncompressive solitary waves, according to the way that the axial strain changes\nas the waves propagate.",
        "positive": "Confinement-induced fractionation and liquid-liquid phase separation of\n  polymer mixtures: The formation of (bio)molecular condensates via liquid-liquid phase\nseparation in cells has received increasing attention, as these coacervates\nplay important functional and regulatory roles within biological systems.\nHowever, the majority of studies focused on the behavior of pure systems in\nbulk solutions, thus neglecting confinement effects and the interplay between\nthe numerous molecules present in cells. To advance our knowledge, we perform\nsimulations of binary polymer mixtures in droplets, considering both\nmonodisperse and polydisperse molecular weight distributions for the longer\npolymer species. We find that confinement induces a spatial separation of the\npolymers by length, with the shorter ones moving to the droplet surface. This\npartitioning causes a distinct increase of the local polymer concentration in\nthe droplet center, which is more pronounced in polydisperse systems.\nConsequently, the systems exhibit liquid-liquid phase separation at average\npolymer concentrations where bulk systems are still in the one-phase regime."
    },
    {
        "anchor": "Transport of ions in hydrophobic nanotubes: The theory of electrokinetic ion transport in cylindrical channels of a fixed\nsurface charge density is revisited. Attention is focused on impact of the\nhydrophobic slippage and mobility of adsorbed surface charges. We formulate\ngeneralised Onsager relations for a cylinder of an arbitrary radius and then\nderive exact expressions for the mean electro-osmotic mobility and\nconductivity. To employ these expressions we perform additional electrostatic\ncalculations, with the special focus on the non-linear electrostatic effects.\nOur theory provides a simple explanation of a giant enhancement of the\nelectrokinetic mobility and conductivity of hydrophobic nanotubes by\nhighlighting the role of appropriate electrostatic and hydrodynamic length\nscales and their ratios. We also propose a novel interpretation of zeta\npotentials of cylindrical channels.",
        "positive": "Dynamical properties of densely packed confined hard-sphere fluids: Numerical solutions of the mode-coupling theory (MCT) equations for a\nhard-sphere fluid confined between two parallel hard walls are elaborated. The\ngoverning equations feature multiple parallel relaxation channels which\nsignificantly complicate their numerical integration. We investigate the\nintermediate scattering functions and the susceptibility spectra close to\nstructural arrest and compare to an asymptotic analysis of the MCT equations.\nWe corroborate that the data converge in the $\\beta$-scaling regime to two\nasymptotic power laws, viz. the critical decay and the von Schweidler law. The\nnumerical results reveal a non-monotonic dependence of the power-law exponents\non the slab width and a non-trivial kink in the low-frequency susceptibility\nspectra. We also find qualitative agreement of these theoretical results to\nevent-driven molecular-dynamics simulations of polydisperse hard-sphere system.\nIn particular, the non-trivial dependence of the dynamical properties on the\nslab width is well reproduced."
    },
    {
        "anchor": "Nonlocal Granular Rheology: Role of Pressure and Anisotropy: We probe the secondary rheology of granular media, by imposing a main flow\nand immersing a vane-shaped probe into the slowly flowing granulate. The\nsecondary rheology is then the relation between the exerted torque T and\nrotation rate \\omega of our probe. In the absence of any main flow, the probe\nexperiences a clear yield-stress, whereas for any finite flow rate, the yield\nstress disappears and the secondary rheology takes on the form of a double\nexponential relation between \\omega and T. This secondary rheology does not\nonly depend on the magnitude of T, but is anisotropic --- which we show by\nvarying the relative orientation of the probe and main flow. By studying the\ndepth dependence of the three characteristic torques that characterize the\nsecondary rheology, we show that for counter flow, the dominant contribution is\nfrictional like --- i.e., T and pressure are proportional for given \\omega ---\nwhereas for co flow, the situation is more complex. Our experiments thus reveal\nthe crucial role of anisotropy for the rheology of granular media.",
        "positive": "Structural anisotropy of directionally dried colloids: Aqueous colloidal dispersions of silica particles become anisotropic when\nthey are dried through evaporation. This anisotropy is generated by a uniaxial\nstrain of the liquid dispersions as they are compressed by the flow of water\ntoward a solidification front. Part of the strain produced by the compression\nis relaxed, and part of it is stored and transferred to the solid. This stored\nelastic strain has consequences for the properties of the solid, where it may\nfacilitate the growth of shear bands, and generate birefringence."
    },
    {
        "anchor": "Comment on \"A new universality class describes Vicsek's flocking phase\n  in physical dimensions'': In a recent preprint, ``A new universality class describes Vicsek's flocking\nphase in physical dimensions'', Patrick Jentsch and Chiu Fan Lee have computed\nthe critical exponents of the Vicsek model in the ordered phase by means of\nfunctional renormalization group methods. In this note, we compare their\nresults with our previous theoretical predictions for the Vicsek model, which\nis expected to be exact in $d=2$ dimensions. We point out that the critical\nexponents predicted by the two theories are extremely close in both $d=2$ and\n$3$ dimensions. We found that both theories fit the current numerical data\nequally well. Extensive numerical simulations for larger system sizes are thus\nhighly desirable to judge which theory is correct.",
        "positive": "Shear-induced fragmentation of Laponite suspensions: Simultaneous rheological and velocity profile measurements are performed in a\nsmooth Couette geometry on Laponite suspensions seeded with glass microspheres\nand undergoing the shear-induced solid-to-fluid (or yielding) transition. Under\nthese slippery boundary conditions, a rich temporal behaviour is uncovered, in\nwhich shear localization is observed at short times, that rapidly gives way to\na highly heterogeneous flow characterized by intermittent switching from\nplug-like flow to linear velocity profiles. Such a temporal behaviour is linked\nto the fragmentation of the initially solid sample into blocks separated by\nfluidized regions. These solid pieces get progressively eroded over time scales\nranging from a few minutes to several hours depending on the applied shear rate\n$\\dot{\\gamma}$. The steady-state is characterized by a homogeneous flow with\nalmost negligible wall slip. The characteristic time scale for erosion is shown\nto diverge below some critical shear rate $\\dot{\\gamma}^\\star$ and to scale as\n$(\\dot{\\gamma}-\\dot{\\gamma}^\\star)^{-n}$ with $n\\simeq 2$ above\n$\\dot{\\gamma}^\\star$. A tentative model for erosion is discussed together with\nopen questions raised by the present results."
    },
    {
        "anchor": "Effect of order-parameter fluctuations on the Halperin-Lubensky-Ma\n  first-order transition in superconductors and liquid crystals: We show that order-parameter fluctuations in a good type-I superconductor or\na liquid crystal always increase the size of the first-order transition. This\nbehavior is eventually changed when the system crosses over to inverted-XY\ncritical behavior, with the size of the first-order transition vanishing as a\npower law with a crossover exponent. We find a good agreement between our\ntheory and a recent experiment on the nematic-smectic-A first-order transition\nin 8CB-10CB mixtures of liquid crystals.",
        "positive": "Depletion-driven four-phase coexistences in discotic systems: Free volume theory (FVT) is a versatile and tractable framework to predict\nthe phase behaviour of mixtures of platelets and non-adsorbing polymer chains\nin a common solvent. Within FVT, three principal reference phases for the hard\nplatelets are considered: isotropic (I), nematic (N), and columnar (C). We\nderive analytical expressions that enable us to systematically trace the\ndifferent types of phase coexistences revealed upon adding depletants and\nconfirm the predictive power of FVT by testing the calculated diagrams against\nphase stability scenarios from computer simulation. A wide range of\n\\textit{multi}-phase equilibria is revealed, involving two-phase isostructural\ntransitions of all phase symmetries (INC) considered as well as the possible\nthree-phase coexistences. Moreover, we identify the system parameters, relative\ndisk shapes and colloid-polymer size ratios, at which four-phase equilibria are\nexpected. These involve a remarkable coexistence of all three phase states\ncommonly encountered in discotics including isostructural coexistences\nI$_1$-I$_2$-N-C, I-N$_1$-N$_2$-C, and I-N-C$_1$-C$_2$."
    },
    {
        "anchor": "Probing the in-mouth texture perception with a biomimetic tongue: An experimental biomimetic tongue-palate system has been developed to probe\nhuman in-mouth texture perception. Model tongues are made from soft elastomers\npatterned with fibrillar structures analogue to human filiform papillae. The\npalate is represented by a rigid flat plate parallel to the plane of the\ntongue. To probe the behavior under physiological flow conditions, deflections\nof model papillae are measured using a novel fluorescent imaging technique\nenabling sub-micrometer resolution of the displacements. Using optically\ntransparent newtonian liquids under steady shear flow, we show that\ndeformations of the papillae allow determining their viscosity from 1 Pa.s down\nto the viscosity of water of 1 mPa.s, in full quantitative agreement with a\nrecently proposed model [Lauga et al., Frontiers in Physics, 2016, 4, 35]. The\ntechnique is further validated for a shear-thinning and optically opaque dairy\nsystem.",
        "positive": "Investigation of the degree of local structural similarity between the\n  parent-liquid and children-crystal states for a model soft matter system: We investigate the degree of local structural similarity between the\nparent-liquid and children-crystal states for a model soft-matter system of\nparticles interacting through the harmonic-repulsive pair potential. At\ndifferent pressures, this simple system crystallizes into several significantly\ndifferent crystal structures. Therefore, the model is well suited for\naddressing the question under consideration. In our studies, we carefully\nanalyze the developments of the pair and triple correlation functions for the\nparent-liquid as the pressure increases. In particular, these considerations\nallow us to address the similarities in the orientational orderings of the\ncorresponding liquid and solid phases. It is demonstrated that the similarities\nin the orientational ordering between the two states extend beyond the first\nand second neighbors. Currently, it is widely accepted that orientational\nordering is important for understanding the behaviors of liquids, supercooled\nliquids, and the development of detailed theories of the crystalization\nprocess. Our results suggest that, up to a certain degree, it might be possible\nto predict the structures of the children-solids from studies of the\nparent-liquids. Our results raise anew a general question of how much insight\ninto the properties of the liquid-state can be gained from drawing a parallel\nwith the solid-state."
    },
    {
        "anchor": "The stability of 12-fold symmetry soft-matter quasicrystals: This letter presents a study on the stability of the 12-fold symmetry\nsoft-matter quasicrystals from the angle of thermodynamics combining dynamics\nof the matter. The results are quantitative, which depend upon only the\nmaterial constants of the novel phase and very simple and intuitive, these\nmaterial constants can be measured by experiments.",
        "positive": "Self-excited motions of volatile drops on swellable sheets: When a volatile droplet is deposited on a floating swellable sheet, it\nbecomes asymmetric, lobed and mobile. We describe and quantify this phenomena\nthat involves nonequilibrium swelling, evaporation and motion, working together\nto realize a self-excitable spatially extended oscillator. Solvent penetration\ncauses the film to swell locally and eventually buckle, changing its shape and\nthe drop responds by moving. Simultaneously, solvent evaporation from the\nswollen film causes it to regain its shape once the droplet has moved away. The\nprocess repeats and leads to complex pulsatile spinning and/or sliding\nmovements. We use a one-dimensional experiment to highlight the slow swelling\nof and evaporation from the film and the fast motion of the drop, a\ncharacteristic of excitable systems. Finally, we provide a phase diagram for\ndroplet excitability as a function of drop size and film thickness and scaling\nlaws for the motion of the droplet."
    },
    {
        "anchor": "A New Perspective on Thermally Fluctuating 2D Elastic Membranes:\n  Introducing Odd Elastic Moduli and Non-Equilibrium Effects: Non-equilibrium and active effects in mesoscopic scale systems have heralded\na new era of scientific inquiries, whether concerning meta-materials or\nbiological systems such as bacteria and cellular components. At mesoscopic\nscales, experimental and theoretical treatments of membranes, and other\nquasi-two-dimensional elastic surfaces cannot generically ignore Brownian\nmotion and other thermal effects. In this paper we aim to study the behavior of\nthermally fluctuating 2-D elastic membranes possessing odd elastic moduli\nembedded in higher dimensions. We implement an isotropic generalization of the\nelastic tensor that includes odd elastic moduli, $K_{odd}$ and $A_{odd}$, that\nbreak conservation of energy and angular momentum respectively, due to\ncite{scheibner2020odd}. Naturally this introduces active and non-equilibrium\neffects. Passive equilibrium thermalized elastic membranes possess effective\n(renormalized) Lam\\'e coefficients that reduce with increasing system size and\na diverging effective bending rigidity. Introducing two odd elastic moduli\nmeans that deformations from a reference state can induce chiral forces that\ncannot be derived from a Hamiltonian. Thus, the behavior of odd elastic\nmembranes must instead be investigated with Langevin equations. If\nfluctuation-dissipation relations hold, we calculate via the renormalization\ngroup that at long length scales, active effects due to $K_{odd}$ can be\neffectively ignored whereas $A_{odd}$ cannot. To validate these findings, we\ndeveloped an advanced force implementation methodology, inspired by the\n$(T)$-scheme prevalent in vertex models. This contributed to a new method for\nthe simulation of elastic membranes in higher dimensions, as detailed recently\nin \\cite{matoz2020wrinkle}. The novelty of the method is that\nmicroscopic/discrete and continuum in-plane elastic moduli are one-to-one and\nthus no coarse-graining is needed.",
        "positive": "Simulating Met-Enkephalin With Population Annealing Molecular Dynamics: Met-enkephalin, one of the smallest opiate peptides and an important\nneurotransmitter, is a widely used benchmarking problem in the field of\nmolecular simulation. Through its range of possible low-temperature\nconformations separated by free-energy barriers it was previously found to be\nhard to thermalize using straight canonical molecular dynamics simulations.\nHere, we demonstrate how one can use the recently proposed population annealing\nmolecular dynamics scheme to overcome these difficulties. We show how the use\nof multi-histogram reweighting allows one to accurately estimate the density of\nstates of the system and hence derive estimates such as the potential energy as\nquasi continuous functions of temperature. We further investigate the\nfree-energy surface as a function of end-to-end distance and radius-of-gyration\nand observe two distinct basins of attraction."
    },
    {
        "anchor": "The pseudo-two-dimensional dynamics in a system of macroscopic rolling\n  spheres: We study in this work the dynamics of a collection of identical hollow\nspheres (ping-pong balls) that rest on a horizontal metallic grid. Fluidization\nis achieved by means of a turbulent air current coming from below. The upflow\nis adjusted so that the particles do not levitate over the grid, resulting in\nquasi-two-dimensional dynamics. We show that the behavior of diffusion and\ncorrelations in this system is particularly rich. Noticeably as well (and\nrelated to the complex dynamical behavior), a variety of phases appear, with\nimportant peculiarities with respect to analogous setups. We observe gas,\nliquid, glass, and hexagonal crystal phases. Most notably, we show that the\nmelting of the hexagonal crystal occurs in coexistence with a liquid phase.\nThis strikingly differs from the corresponding transition in a purely\ntwo-dimensional systems of air-fluidized disks, for which no phase coexistence\nhas been reported in the literature.",
        "positive": "Structure and equation-of-state of a disordered system of shape\n  anisotropic patchy particles: We present a new two dimensional model for elliptic (i.e., shape anisotropic)\npatchy colloids, where the impenetrable core of the particles is decorated on\nits co-)vertices by Kern-Frenkel type of patches. Using (i) well-documented\ncriteria for the overlap of the undecorated ellipses and (ii) proposing new\ncriteria that give evidence if the patchy regions of two particles interact we\nperform extensive Monte Carlo simulations in the NPT ensemble. Considering\nelliptic particles of aspect ratios \\{kappa} = 2, 4, and 6 with two patches\nlocated at the co-vertices and choosing representative values for the\ntemperature we study on a semi-quantitative level the emerging disordered\nphases in terms of snapshots and radial distribution functions and present\nresults for the equation-of-state."
    },
    {
        "anchor": "Polymer Entanglement Dynamics: Role of Attractive Interactions: The coupled dynamics of entangled polymers which span a broad time and length\nscales govern the unique viscoelastic properties of polymers. To follow chain\nmobility by numerical simulations from the intermediate Rouse and reptation\nregimes to the late time diffusive regime, highly coarse grained models with\npurely repulsive interactions between monomers are widely used since they are\ncomputationally the most efficient. Here using large scale molecular dynamics\nsimulations the effect of including the attractive interaction between monomers\non the dynamics of entangled polymers melts is explored for the first time over\nwide temperature range. Attractive interactions has little effect on the local\npacking for all temperatures T and on the chain mobility for T higher than\nabout twice the glass transition Tg. These results, across a broad range of\nmolecular weight, show that to study the dynamics of entangled polymers melts\nthe interactions can be treated as pure repulsive, confirming a posteriori the\nvalidity of previous studies and opening the way to new large scale numerical\nsimulations.",
        "positive": "Thermodynamic perturbation theory for self-assembling mixtures of\n  divalent single patch colloids: In this work we extend Wertheim's thermodynamic perturbation theory (TPT) to\nbinary mixtures (species A and species B) of patchy colloids where each species\nhas a single patch which can bond a maximum of twice (divalent). Colloids are\ntreated as hard spheres with a directional conical asssociation site. We\nrestrict the system such that only patches between unlike species share\nattractions; meaning there are AB attractions but no AA or BB attractions. The\ntheory is derived in Wertheim's two density formalism for one site associating\nfluids. Since the patches are doubly bondable, associated chains, of all chain\nlengths, as well as 4-mer rings consisting of two species A and two species B\ncolloids are accounted for. With the restriction of only AB attractions,\ntriatomic rings of doubly bonded colloids, which dominate the corresponding\npure component case, cannot form. The theory is shown to be in good agreement\nwith Monte Carlo simulaion data for the structure and thermodynamics of these\npatchy colloid mixtures as a function of temperature, density, patch size and\ncomposition. It is shown that 4-mer rings dominate at low temperatures,\ninhibiting the polymerization of the mixture into long chains. Mixtures of this\ntype have been recently synthesized by researchers. This work provides the\nfirst theory capable of accurately modelling these mixtures."
    },
    {
        "anchor": "Brownian ratchet in a thermal bath driven by Coulomb friction: The rectification of unbiased fluctuations, also known as the ratchet effect,\nis normally obtained under statistical non-equilibrium conditions. Here we\npropose a new ratchet mechanism where a thermal bath solicits the random\nrotation of an asymmetric wheel, which is also subject to Coulomb friction due\nto solid-on-solid contacts. Numerical simulations and analytical calculations\ndemonstrate a net drift induced by friction. If the thermal bath is replaced by\na granular gas, the well known granular ratchet effect also intervenes,\nbecoming dominant at high collision rates. For our chosen wheel shape the\ngranular effect acts in the opposite direction with respect to the\nfriction-induced torque, resulting in the inversion of the ratchet direction as\nthe collision rate increases. We have realized a new granular ratchet\nexperiment where both these ratchet effects are observed, as well as the\npredicted inversion at their crossover. Our discovery paves the way to the\nrealization of micro and sub-micrometer Brownian motors in an equilibrium\nfluid, based purely upon nano-friction.",
        "positive": "Algorithm for molecular dynamics simulations of spin liquids: A new symplectic time-reversible algorithm for numerical integration of the\nequations of motion in magnetic liquids is proposed. It is tested and applied\nto molecular dynamics simulations of a Heisenberg spin fluid. We show that the\nalgorithm exactly conserves spin lengths and can be used with much larger time\nsteps than those inherent in standard predictor-corrector schemes. The results\nobtained for time correlation functions demonstrate the evident dynamic\ninterplay between the liquid and magnetic subsystems."
    },
    {
        "anchor": "Determining the Anchoring Strength of a Capillary Using Topological\n  Defects: We consider a smectic-A* in a capillary with surface anchoring that favors\nparallel alignment. If the bulk phase of the smectic is the standard\ntwist-grain-boundary phase of chiral smectics, then there will be a critical\nradius below which the smectic will not have any topological defects. Above\nthis radius a single screw dislocation in the center of the capillary will be\nfavored. Along with surface anchoring, a magnetic field will also suppress the\nformation of a screw dislocation. In this note, we calculate the critical field\nat which a defect is energetically preferred as a function of the surface\nanchoring strength and the capillary radius. Experiments at a few different\nradii could thus determine the anchoring strength.",
        "positive": "Twisted loxodromes in spindle-shaped polymer nematics: We develop an energetic model that captures the twisting behavior of\nspindle-shaped polymer microparticles with nematic ordering, which display\nremarkably different twisting behavior to ordinary nematics confined to\nspindles. We have previously developed a geometric model of the twisting, based\non experimental observations, in which we showed that the twist pattern follows\nloxodrome spirals [Ansell et. al., Phys. Rev. Lett., 123, 157801 (2019)]. In\nthis study, we first consider a spindle-shaped surface and show that the\nloxodrome twisting behavior of our system can be captured by the Frank free\nenergy of the nematic with an additional term constraining the length of the\nintegral curves of the system. We then extend the ideas of this model to the\nbulk and explore the parameter space for which the twisted loxodrome solution\nis energetically favorable."
    },
    {
        "anchor": "Kinetic theory of motility induced phase separation for active Brownian\n  particles: When two active Brownian particles collide, they slide along each other until\nthey can continue their free motion. For persistence lengths much larger than\nthe particle diameter, the directors do not change, but the collision can be\nmodeled as producing a net displacement on the particles compared to their free\nmotion in the absence of the encounter. With these elements, a\nBoltzmann--Enskog-like kinetic theory is built. A linear stability analysis of\nthe homogeneous state predicts a density instability resulting from the\neffective velocity reduction of tagged particles predicted by the theory.",
        "positive": "Monte Carlo simulation study of diblock copolymer self assembly: A technique is presented which maps the parameters of a bead spring model,\nusing the Flory Huggins theory, to a specific experimental system. By keeping\nonly necessary details, for the description of these systems, the mapping\nprocedure turns into an estimation of a few characteristic parameters. An asset\nof this technique is that it is simple to apply and captures the behavior of\nblock copolymer phase separation. In our study this mapping technique is\nutilized in conjunction with a Monte Carlo (MC) algorithm to perform\nsimulations on block copolymer systems. The microphase separation is\ninvestigated in the bulk and under confinement, on unpatterned and patterned\nsurfaces."
    },
    {
        "anchor": "Conformations, correlations, and instabilities of a flexible fiber in an\n  active fluid: Fluid-structure interactions between active and passive components are\nimportant for many biological systems to function. A particular example is\nchromatin in the cell nucleus, where ATP-powered processes drive coherent\nmotions of the chromatin fiber over micron lengths. Motivated by this system,\nwe develop a multiscale model of a long flexible polymer immersed in a\nsuspension of active force dipoles as an analog to a chromatin fiber in an\nactive fluid -- the nucleoplasm. Linear analysis identifies an orientational\ninstability driven by hydrodynamic and alignment interactions between the fiber\nand the suspension, and numerical simulations show activity can drive coherent\nmotions and structured conformations. These results demonstrate how active and\npassive components, connected through fluid-structure interactions, can\ngenerate coherent structures and self-organize on large scales.",
        "positive": "Tissue hydraulics: physics of lumen formation and interaction: Lumen formation plays an essential role in the morphogenesis of tissues\nduring development. Here we review the physical principles that play a role in\nthe growth and coarsening of lumens. Solute pumping by the cell, hydraulic\nflows driven by differences of osmotic and hydrostatic pressures, balance of\nforces between extracellular fluids and cell-generated cytoskeletal forces, and\nelectro-osmotic effects have been implicated in determining the dynamics and\nsteady-state of lumens. We use the framework of linear irreversible\nthermodynamics to discuss the relevant force, time and length scales involved\nin these processes. We focus on order of magnitude estimates of physical\nparameters controlling lumen formation and coarsening."
    },
    {
        "anchor": "Simple theory for oscillatory charge profile in ionic liquids near a\n  charged wall: The mesoscopic field theory for ionic systems [A. Ciach and G. Stell, J. Mol.\nLiq. 87, 255 (2000)] is extended to the system with charged boundaries. A very\nsimple expression for the excess grand potential functional of the charge\ndensity is developed. The size of hard-cores of ions is taken into account in\nthe expression for the internal energy. The functional is suitable for a\ndescription of a distribution of ions in ionic liquids and ionic liquid\nmixtures with neutral components near a weakly charged wall. The Euler-Lagrange\nequation is obtained, and solved for a flat confining surface. An exponentially\ndamped oscillatory charge density profile is obtained. The electrostatic\npotential for the restricted primitive model agrees with the simulation results\non a semiquantitative level.",
        "positive": "Cell division: a source of active stress in cellular monolayers: We introduce the notion of cell division-induced activity and show that the\ncell division generates extensile forces and drives dynamical patterns in cell\nassemblies. Extending the hydrodynamic models of lyotropic active nematics we\ndescribe turbulent-like velocity fields that are generated by the cell division\nin a confluent monolayer of cells. We show that the experimentally measured\nflow field of dividing Madin-Darby Canine Kidney (MDCK) cells is reproduced by\nour modeling approach. Division-induced activity acts together with intrinsic\nactivity of the cells in extensile and contractile cell assemblies to change\nthe flow and director patterns and the density of topological defects. Finally\nwe model the evolution of the boundary of a cellular colony and compare the\nfingering instabilities induced by cell division to experimental observations\non the expansion of MDCK cell cultures."
    },
    {
        "anchor": "A nonlocal contact formulation for confined granular systems: We present a nonlocal formulation of contact mechanics that accounts for the\ninterplay of deformations due to multiple contact forces acting on a single\nparticle. The analytical formulation considers the effects of nonlocal\nmesoscopic deformations characteristic of confined granular systems and,\ntherefore, removes the classical restriction of independent contacts. This is\nin sharp contrast to traditional contact mechanics theories, which are strictly\nlocal and assume that contacts are independent regardless the confinement of\nthe particles. For definiteness, we restrict attention to elastic spheres in\nthe absence of gravitational forces, adhesion or friction. Hence, a notable\nfeature of the nonlocal formulation is that, when nonlocal effects are\nneglected, it reduces to Hertz theory. Furthermore, we show that, under the\npreceding assumptions and up to moderate macroscopic deformations, the\npredictions of the nonlocal contact formulation are in remarkable agreement\nwith detailed finite-element simulations and experimental observations, and in\nlarge disagreement with Hertz theory predictions---supporting that the\nassumption of independent contacts only holds for small deformations. The\ndiscrepancy between the extended theory presented in this work and Hertz theory\nis borne out by studying periodic homogeneous systems and disordered\nheterogeneous systems.",
        "positive": "Machine learning-informed structuro-elastoplasticity predicts ductility\n  of disordered solids: All solids yield under sufficiently high mechanical loads. Below yield, the\nmechanical responses of all disordered solids are nearly alike, but above yield\nevery different disordered solid responds in its own way. Brittle systems can\nshatter without warning, like ordinary window glass, or exhibit strain\nlocalization prior to fracture, like metallic or polymeric glasses. Ductile\nsystems, e.g. foams like shaving cream or emulsions like mayonnaise, can flow\nindefinitely with no strain localization. While there are empirical strategies\nfor tuning the degree of strain localization, there is no framework that\nexplains their effectiveness or limitations. We show that\nStructuro-Elastoplastic (StEP) models provide microscopic understanding of how\nstrain localization depends on the interplay of structure, plasticity and\nelasticity."
    },
    {
        "anchor": "Mechanics of a snap-fit: Snap-fits are versatile mechanical designs in industrial products, which\nenable the repeated assembling and disassembling of two solid parts. This\nimportant property is attributed to a fine balance between geometry, friction,\nand bending elasticity. In the present study, we combine theory, simulation,\nand experiment to reveal the fundamental physical principles of snap-fit\nfunctions in the simplest possible setup consisting of a rigid cylinder and a\nthin elastic shell. We construct a phase diagram using geometric parameters and\nidentify four distinct mechanical phases. We develop analytical predictions\nbased on the linear elasticity theory combined with the law of static friction\nand rationalize the numerical and experimental results. The study reveals how\nan operational asymmetry of snap-fits (i.e., easy to assemble but difficult to\ndisassemble) emerges from an exquisite combination of geometry, elasticity, and\nfriction and suggests optimization of the tunable functionalities for a range\nof mechanical designs.",
        "positive": "Rheology of moderated dilute suspensions of star colloids: the shape\n  factor: Star colloids are rigid particles with long and slender arms connected to a\ncentral core. We show numerically that the colloid shapes control the rheology\nof their suspensions. In particular, colloids with curved arms and hooks can\nentangle with neighbor particles and form large clusters that can sustain high\nstresses. When a large cluster permeates the whole system the viscosity\nincreases many fold. Contrary to the case of spherical colloids we observe that\nthese effects are very strong even at moderate volumes fraction over a wide\nrange of P\\'eclet numbers."
    },
    {
        "anchor": "Comments to topological defects in bilayer vesicles: To explain the details of bilayer vesicle aggregation, we revised the anyon\nmodel for lipid domains formation in closed vesicles of lipid-cholesterol\nsystem $DPPC/DLPC$/cholesterol, which was measured by Feigenson and Tokumasu\n(Biophys. Journal, 2001, 2003) in frames of the different optical experiments\nand atomic-force microscopy.",
        "positive": "Scaling Behaviors of a Polymer Ejected from a Cavity through a Small\n  Pore: Langevin dynamics simulations are performed to investigate ejection dynamics\nof spherically confined flexible polymers through a pore. By varying the chain\nlength $N$ and the initial volume fraction $\\phi_0$ of the monomers, two\nscaling behaviors for the ejection velocity $v$ on the monomer number $m$ in\nthe cavity are obtained: $v \\sim m^{1.25}\\phi_0^{1.25}/N^{1.6}$ for large $m$\nand $v \\sim m^{-1.4}$ as $m$ is small. A robust scaling theory is developed by\ndividing the process into the confined and the non-confined stages, and the\ndynamical equation is derived via the study of energy dissipation. After\ntrimming the prior stage related to the escape of the head monomer across the\npore, the evolution of $m$ is shown to be well described by the scaling theory.\nThe ejection time exhibits two proper scaling behaviors:\n$N^{2/(3\\nu)+y_1}\\phi_0^{-2/(3\\nu)}$ and $N^{2+y_2}$ under the large and small\n$\\phi_0$- or $N$-conditions, respectively, where $y_1=1/3$, $y_2=1-\\nu$, and\n$\\nu$ is the Flory exponent."
    },
    {
        "anchor": "Molecular Dynamics Simulation of Semiflexible Polyampholyte Brushes -\n  The Effect of Charged Monomers Sequence: Planar brushes formed by end-grafted semiflexible polyampholyte chains, each\nchain containing equal number of positively and negatively charged monomers is\nstudied using molecular dynamics simulations. Keeping the length of the chains\nfixed, dependence of the average brush thickness and equilibrium statistics of\nthe brush conformations on the grafting density and the salt concentration are\nobtained with various sequences of charged monomers. When similarly charged\nmonomers of the chains are arranged in longer blocks, the average brush\nthickness is smaller and dependence of brush properties on the grafting density\nand the salt concentration is stronger. With such long blocks of similarly\ncharged monomers, the anchored chains bond to each other in the vicinity of the\ngrafting surface at low grafting densities and buckle toward the grafting\nsurface at high grafting densities.",
        "positive": "Self-propelling Microdroplets Generated and Sustained by Liquid-liquid\n  Phase Separation in Confined Spaces: Flow transport in confined spaces is ubiquitous in technological processes,\nranging from separation and purification of pharmaceutical ingredients by\nmicroporous membranes and drug delivery in biomedical treatment to chemical and\nbiomass conversion in catalyst-packed reactors and carbon dioxide\nsequestration. In this work, we suggest a distinct pathway for enhanced liquid\ntransport in a confined space via self-propelling microdroplets. These\nmicrodroplets can form spontaneously from localized liquid-liquid phase\nseparation as a ternary mixture is diluted by a diffusing poor solvent. High\nspeed images reveal how the microdroplets grow, break up and propel rapidly\nalong the solid surface, with a maximal velocity up to ~160 um/s, in response\nto a sharp concentration gradient resulting from phase separation. The\nmicrodroplet self-propulsion induces a replenishing flow between the walls of\nthe confined space towards the location of phase separation, which in turn\ndrives the mixture out of equilibrium and leads to a repeating cascade of\nevents. Our findings on the complex and rich phenomena of self-propelling\ndroplets suggest an effective approach to enhanced flow motion of\nmulticomponent liquid mixtures within confined spaces for time effective\nseparation and smart transport processes."
    },
    {
        "anchor": "Thermodynamics of star polymer solutions: a coarse-grained study: We consider a coarse-grained (CG) model with pairwise interactions, suitable\nto describe low-density solutions of star-branched polymers of functionality\n$f$. Each macromolecule is represented by a CG molecule with $(f+1)$\ninteraction sites, which captures the star topology. Potentials are obtained by\nrequiring the CG model to reproduce a set of distribution functions computed in\nthe microscopic model in the zero-density limit. Explicit results are given for\n$f=6,12$ and $40$. We use the CG model to compute the osmotic equation of state\nof the solution for concentrations $c$ such that $\\Phi_p = c/c^* \\lesssim 1$,\nwhere $c^*$ is the overlap concentration. We also investigate in detail the\nphase diagram for f=40, identifying the boundaries of the solid intermediate\nphase. Finally, we investigate how the polymer size changes with $c$. For\n$\\Phi_p\\lesssim 0.3$ polymers become harder as $f$ increases at fixed reduced\nconcentration $c/c^*$. On the other hand, for $\\Phi_p\\gtrsim 0.3$, polymers\nshow the opposite behavior: At fixed $\\Phi_p$, the larger the value of $f$, the\nlarger their size reduction is.",
        "positive": "Three-body problem for Langevin dynamics with different temperatures: A mixture of Brownian particles at different temperatures has been a useful\nmodel for studying the out-of-equilibrium properties of systems made up of\nmicroscopic components with differing levels of activity. This model was\npreviously studied analytically for two-particle interactions in the dilute\nlimit, yielding a Boltzmann-like two-particle distribution with an effective\ntemperature. Like the Newtonian two and three-body problems, we ask here\nwhether the two-particle results can be extended to three-particle interactions\nto get the three-particle distributions. By considering the special solvable\ncase of pairwise quadratic interactions, we show that, unlike the two-particle\ndistribution, the three-particle distribution cannot in general be\nBoltzmann-like with an effective temperature. We instead find that the steady\nstate distribution of any two particles in a triplet depends on the properties\nof and interactions with the third particle, leading to some unexpected\nbehaviors not present in equilibrium."
    },
    {
        "anchor": "Cell theory of the electroosmosis in the concentrated diaphragms\n  consisting of spheric particles of colloid dispersity with account of the\n  insoluble boundary layer influence: The electroosmotic transfer (ratio of velocity of liquid to electric current\ndensity) and conductivity of disperse system were calculated as functions of\nvolume fraction of disperse particles. The considered model of electric double\nlayer (EDL) was generalized by taking into account the reducing dissolving\nability of liquid near the surface (non-dissolving boundary layer). The problem\nwas solved for limiting case of large degree of EDL overlapping in\ninterparticle space. The obtained results explain the main features of\nexperimental data.",
        "positive": "Glassy state of native collagen fibril: Our micromechanical experiments show that at physiological temperatures type\nI collagen fibril has several basic features of the glassy state. The\ntransition out of this state [softening transition] essentially depends on the\nspeed of heating v, e.g., for v=1 C/min it occurs around 70 C and is displayed\nby a peak of the internal friction and decreasing Young's modulus. The\nsoftening transition decreases by 45 C upon decreasing the heating speed to\nv=0.1 C/min. For temperatures 20-30 C the native collagen fibril demonstrates\nfeatures of mechanical glassines at oscillation frequencies 0.1-3 kHz; in\nparticular, the internal friction has a sharp maximum as a function of the\nfrequency. This is the first example of biopolymer glassines at physiological\ntemperatures, because well-known glassy features of DNA and globular proteins\nare seen only for much lower temperatures (around 200 K)."
    },
    {
        "anchor": "The Aggregation Kinetics of a Simulated Telechelic Polymer: We investigate the aggregation kinetics of a simulated telechelic polymer\ngel. In the hybrid Molecular Dynamics (MD) / Monte Carlo (MC) algorithm,\naggregates of associating end groups form and break according to MC rules,\nwhile the position of the polymers in space is dictated by MD. As a result, the\naggregate sizes change every time step. In order to describe this aggregation\nprocess, we employ master equations. They define changes in the number of\naggregates of a certain size in terms of reaction rates. These reaction rates\nindicate the likelihood that two aggregates combine to form a large one, or\nthat a large aggregate splits into two smaller parts. The reaction rates are\nobtained from the simulations for a range of temperatures.\n  Our results indicate that the rates are not only temperature dependent, but\nalso a function of the sizes of the aggregates involved in the reaction. Using\nthe measured rates, solutions to the master equations are shown to be stable\nand in agreement with the aggregate size distribution, as obtained directly\nfrom simulation data. Furthermore, we show how temperature induced variations\nin these rates give rise to the observed changes in the aggregate distribution\nthat characterizes the sol-gel transition.",
        "positive": "Motor crosslinking augments elasticity in active nematics: In active materials, uncoordinated internal stresses lead to emergent\nlong-range flows. An understanding of how the behavior of active materials\ndepends on mesoscopic (hydrodynamic) parameters is developing, but there\nremains a gap in knowledge concerning how hydrodynamic parameters depend on the\nproperties of microscopic elements. In this work, we combine experiments and\nmultiscale modeling to relate the structure and dynamics of active nematics\ncomposed of biopolymer filaments and molecular motors to their microscopic\nproperties, in particular motor processivity, speed, and valency. We show that\ncrosslinking of filaments by both motors and passive crosslinkers not only\naugments the contributions to nematic elasticity from excluded volume effects\nbut dominates them. By altering motor kinetics we show that a competition\nbetween motor speed and crosslinking results in a nonmonotonic dependence of\nnematic flow on motor speed. By modulating passive filament crosslinking we\nshow that energy transfer into nematic flow is in large part dictated by\ncrosslinking. Thus motor proteins both generate activity and contribute to\nnematic elasticity. Our results provide new insights for rationally engineering\nactive materials."
    },
    {
        "anchor": "Imprinting the memory into paste and its visualization as crack patterns\n  in drying process: In the drying process of paste, we can imprint into the paste the order how\nit should be broken in the future. That is, if we vibrate the paste before it\nis dried, it remembers the direction of the initial external vibration, and the\nmorphology of resultant crack patterns is determined solely by the memory of\nthe direction. The morphological phase diagram of crack patterns and the\nrheological measurement of the paste show that this memory effect is induced by\nthe plasticity of paste.",
        "positive": "Scaling Perspectives of Underscreening in Concentrated Electrolyte\n  Solutions: We present a scaling view of underscreening observed in salt solutions in the\nrange of concentrations greater than about 1M, in which the screening length\nincreases with concentration. The system consists of hydrated clusters of\npositive and negative ions with a single unpaired ion as suggested by recent\nsimulations. The environment of this ion is more hydrated than average which\nleads to a self-similar situation in which the size of this environment scales\nwith the screening length. The prefactor involves the local dielectric constant\nand the cluster density. The scaling arguments as well as the cluster model\nlead to scaling of the screening length with the ion concentration, in\nagreement with observations."
    },
    {
        "anchor": "Monovalent Ion Condensation at the Electrified Liquid/Liquid Interface: X-ray reflectivity studies demonstrate the condensation of a monovalent ion\nat the electrified interface between electrolyte solutions of water and\n1,2-dichloroethane. Predictions of the ion distributions by standard\nPoisson-Boltzmann (Gouy-Chapman) theory are inconsistent with these data at\nhigher applied interfacial electric potentials. Calculations from a\nPoisson-Boltzmann equation that incorporates a non-monotonic ion-specific\npotential of mean force are in good agreement with the data.",
        "positive": "Glass Transition Temperature in Polystyrene Supported Thin Films: a\n  SPM-based Investigation of the Role of Molecular Entanglement: The viscoelastic properties of thin polymeric films represent a central\nissue, especially for nanotechnological applications. In particular, it is\nhighly relevant the dependence of viscoelasticity on the temperature. For\npolystyrene it is known that the glass transition temperature is dependent on\nthe film thickness. At present, there is wide agreement on the importance of\nthe two interfaces that the films form with the air and with the substrate. The\nrelevance of molecular entanglement has been also stressed for the case of\nsuspended films. However, the role of molecular entanglement on the glass\ntransition temperature of supported films still remains elusive. In order to\ninvestigate the viscoelastic properties of thin films on the nanoscale, we have\nemployed a scanning probe microscope suitably modified in order to monitor the\nindentation of a tip into a polymeric film during a given lapse of time with\nthe application of a constant load. Thin polystyrene films have been prepared\non a range of different substrates: native silicon oxide, hydrogen-terminated\nsilicon and polystyrene brushes. In particular, we have considered polystyrene\nmolecules with molecular weight values below and above the critical value for\nthe occurrence of molecular entanglement. We find that, for samples where\nmolecular entanglement can occur accompanied by a strong interaction with the\nsubstrate either by means of chemical bonds or physisorption, the glass\ntransition temperature of thin films increases back to values comparable with\nthose of thick films. This phenomenon is envisioned to be of great relevance in\nthose cases where one needs to improve the adhesion and/or to control the\nviscoelastic properties of thin films."
    },
    {
        "anchor": "Combing a double helix: Combing hair involves brushing away the topological tangles in a collective\ncurl. Using a combination of experiment and computation, we study this problem\nthat naturally links topology, geometry and mechanics. Observations show that\nthe dominant interactions in hair are those of a two-body nature, corresponding\nto a braided homochiral double helix. Using this minimal model, we study the\ndetangling of an elastic double helix via a single stiff tine that moves along\nit, leaving two untangled filaments in its wake. Our results quantify how the\nforces of detangling are correlated with the magnitude and spatial extent of\nthe link density, a topological quantity, that propagates ahead of the tine.\nThis in turn provides a measure of the maximum characteristic length of a\nsingle combing stroke, and thus the trade-offs between comfort, efficiency and\nspeed of combing in the many-body problem on a head of hair.",
        "positive": "Calculating particle pair potentials from fluid-state pair correlations:\n  Iterative Ornstein-Zernike Inversion: An iterative Monte Carlo inversion method for the calculation of particle\npair potentials from given particle pair correlations is proposed in this\npaper. The new method, which is best referred to as Iterative Ornstein-Zernike\nInversion, represents a generalization and an improvement of the established\nIterative Boltzmann Inversion technique [Reith, P\\\"{u}tz \\& M\\\"{u}ller-Plathe,\nJ. Comput. Chem. 24, 1624 (2003)]. Our modification of Iterative Boltzmann\nInversion consists of replacing the potential of mean force as an approximant\nfor the pair potential with another, generally more accurate approximant that\nis based on a trial bridge function in the Ornstein-Zernike integral equation\nformalism. As an input, the new method requires the particle pair correlations\nboth in real space and in the Fourier conjugate wavenumber space. An\naccelerated iteration method is included in the discussion, by which the\nrequired number of iterations can be greatly reduced below that of the simple\nPicard iteration that underlies most common implementations of Iterative\nBoltzmann Inversion. Comprehensive tests with various pair potentials show that\nthe new method generally surpasses the Iterative Boltzmann Inversion method in\nterms of reliability of the numerical solution for the particle pair potential."
    },
    {
        "anchor": "Hydrodynamic effects on concentration fluctuations in multicomponent\n  membranes: We investigate the hydrodynamic effects on the dynamics of critical\nconcentration fluctuations in multicomponent fluid membranes. Two geometrical\ncases are considered; (i) confined membrane case and (ii) supported membrane\ncase. We numerically calculate the wavenumber dependence of the effective\ndiffusion coefficient by changing the temperature and/or the thickness of the\nbulk fluid. For some limiting cases, the result is compared with the previously\nobtained analytical expression. An analogy of the multicomponent membrane to 2D\nmicroemulsion is explored for the confined membrane geometry.",
        "positive": "A Dimensionally-Reduced Nonlinear Elasticity Model for Liquid Crystal\n  Elastomer Strips with Transverse Curvature: Liquid Crystalline Elastomers (LCEs) are active materials that are of\ninterest due to their programmable response to various external stimuli such as\nlight and heat. When exposed to these stimuli, the anisotropy in the response\nof the material is governed by the nematic director, which is a continuum\nparameter that is defined as the average local orientation of the mesogens in\nthe liquid crystal phase. This nematic director can be programmed to be\nheterogeneous in space, creating a vast design space that is useful for\napplications ranging from artificial ligaments to deployable structures to\nself-assembling mechanisms. Even when specialized to long and thin strips of\nLCEs -- the focus of this work -- the vast design space has required the use of\nnumerical simulations to aid in experimental discovery. To mitigate the\ncomputational expense of full 3-d numerical simulations, several\ndimensionally-reduced rod and ribbon models have been developed for LCE strips,\nbut these have not accounted for the possibility of initial transverse\ncurvature, like carpenter's tape spring. Motivated by recent experiments\nshowing that transversely-curved LCE strips display a rich variety of\nconfigurations, this work derives a dimensionally-reduced 1-d model for\npre-curved LCE strips. The 1-d model is validated against full 3-d finite\nelement calculations, and it is also shown to capture experimental\nobservations, including tape-spring-like localizations, in activated LCE\nstrips."
    },
    {
        "anchor": "Avalanche-like fluidization of a non-Brownian particle gel: We report on the fluidization dynamics of an attractive gel composed of\nnon-Brownian particles made of fused silica colloids. Extensive rheology\ncoupled to ultrasonic velocimetry allows us to characterize the global stress\nresponse together with the local dynamics of the gel during shear startup\nexperiments. In practice, after being rejuvenated by a preshear, the gel is\nleft to age during a time $t_w$ before being submitted to a constant shear rate\n$\\dot \\gamma$. We investigate in detail the effects of both $t_w$ and $\\dot\n\\gamma$ on the fluidization dynamics and build a detailed state diagram of the\ngel response to shear startup flows. The gel may either display transient shear\nbanding towards complete fluidization, or steady-state shear banding. In the\nformer case, we unravel that the progressive fluidization occurs by successive\nsteps that appear as peaks on the global stress relaxation signal. Flow imaging\nreveals that the shear band grows up to complete fluidization of the material\nby sudden avalanche-like events which are distributed heterogeneously along the\nvorticity direction and correlated to large peaks in the slip velocity at the\nmoving wall. These features are robust over a wide range of values of $t_w$ and\n$\\dot \\gamma$, although the very details of the fluidization scenario vary with\n$\\dot \\gamma$. Finally, the critical shear rate $\\dot \\gamma^*$ that separates\nsteady-state shear-banding from steady-state homogeneous flow depends on the\nwidth on the shear cell and exhibits a nonlinear dependence with $t_w$. Our\nwork brings about valuable experimental data on transient flows of attractive\ndispersions, highlighting the subtle interplay between shear, wall slip and\naging which modeling constitutes a major challenge that has not been met yet.",
        "positive": "Structural Dependence of the Molecular Mobility in the Amorphous\n  Fractions of Polylactide: Fragility index and cooperativity length characterizing the molecular\nmobility in the amorphous phase are for the first time calculated in drawn\npolylactide (PLA). The microstructure of the samples is investigated from\nwide-angle X-ray scattering (WAXS) whereas the amorphous phase dynamics are\nrevealed from broadband dielectric spectroscopy (BDS) and temperature-modulated\ndifferential scanning calorimetry (TMDSC). The drawing processes induce the\ndecrease of both cooperativity and fragility with the orientation of the\nmacromolecules. Post-drawing annealing reveals an unusual absence of\ncorrelation between the evolutions of cooperativity length and fragility. The\ncooperativity length remains the same compared to the drawn sample while a huge\nincrease of the fragility index is recorded. By splitting the fragility index\nin a volume contribution and an energetic contribution, it is revealed that the\namorphous phase in annealed samples exhibits a high energetic parameter, even\nexceeding the amorphous matrix value. It is assumed that the relaxation process\nis driven in such a way that the volume hindrance caused by the\nthermomechanical constraint is compensated by the acceleration of segmental\nmotions linked to the increase of degrees of freedom. This result should also\ncontribute to the understanding of the constraint slackening in the amorphous\nphase during annealing of drawn PLA, which causes among others the decrease of\nits barrier properties."
    },
    {
        "anchor": "Why does hydronium diffuse faster than hydroxide in liquid water?: Proton transfer via hydronium and hydroxide ions in water is ubiquitous. It\nunderlies acid-base chemistry, certain enzyme reactions, and even infection by\nthe flu. Despite two-centuries of investigation, the mechanism underlying why\nhydronium diffuses faster than hydroxide in water is still not well understood.\nHerein, we employ state of the art Density Functional Theory based molecular\ndynamics, with corrections for nonlocal van der Waals interactions, and\nself-interaction in the electronic ground state, to model water and the\nhydrated water ions. At this level of theory, structural diffusion of hydronium\npreserves the previously recognized concerted behavior. However, by contrast,\nproton transfer via hydroxide is dominated by stepwise events, arising from a\nstabilized hyper-coordination solvation structure that discourages proton\ntransfer. Specifically, the latter exhibits non-planar geometry, which agrees\nwith neutron scattering results. Asymmetry in the temporal correlation of\nproton transfer enables hydronium to diffuse faster than hydroxide.",
        "positive": "Crystal growth from a supersaturated melt: relaxation of the\n  solid-liquid dynamic stiffness: We discuss the growth process of a crystalline phase out of a metastable\nover-compressed liquid that is brought into contact with a crystalline\nsubstrate. The process is modeled by means of molecular dynamics. The particles\ninteract via the Lennard-Jones potential and their motion is locally\nthermalized by Langevin dynamics. We characterize the relaxation process of the\nsolid-liquid interface, showing that the growth speed is maximal for liquid\ndensities above the solid coexistence density, and that the structural\nproperties of the interface rapidly converge to equilibrium-like properties. In\nparticular, we show that the off-equilibrium dynamic stiffness can be extracted\nusing capillary wave theory arguments, even if the growth front moves fast\ncompared to the typical diffusion time of the compressed liquid, and that the\ndynamic stiffness converges to the equilibrium stiffness in times much shorter\nthan the diffusion time."
    },
    {
        "anchor": "Electric Field Induced Macroscopic Cellular Phase of Nanoparticles: A suspension of nanoparticles with very low volume fraction is found to\nassemble into a macroscopic cellular phase under the collective influence of AC\nand DC voltages. Systematic study of this phase transition shows that it was\nthe result of electrophoretic assembly into a two-dimensional configuration\nfollowed by spinodal decomposition into particle-rich walls and particle-poor\ncells mediated principally by electrohydrodynamic flow. This mechanistic\nunderstanding reveals two characteristics needed for a cellular phase to form,\nnamely 1) a system that is considered two dimensional and 2) short-range\nattractive, long-range repulsive interparticle interactions. In addition to\ndetermining the mechanism underpinning the formation of the cellular phase,\nthis work presents a method to reversibly assemble microscale continuous\nstructures out of nanoscale particles in a manner that may enable the creation\nof materials that impact diverse fields including energy storage and\nfiltration.",
        "positive": "Fluid Vesicles in Flow: We review the dynamical behavior of giant fluid vesicles in various types of\nexternal hydrodynamic flow. The interplay between stresses arising from\nmembrane elasticity, hydrodynamic flows, and the ever present thermal\nfluctuations leads to a rich phenomenology. In linear flows with both\nrotational and elongational components, the properties of the tank-treading and\ntumbling motions are now well described by theoretical and numerical models. At\nthe transition between these two regimes, strong shape deformations and\namplification of thermal fluctuations generate a new regime called trembling.\nIn this regime, the vesicle orientation oscillates quasi-periodically around\nthe flow direction while asymmetric deformations occur. For strong enough\nflows, small-wavelength deformations like wrinkles are observed, similar to\nwhat happens in a suddenly reversed elongational flow. In steady elongational\nflow, vesicles with large excess areas deform into dumbbells at large flow\nrates and pearling occurs for even stronger flows. In capillary flows with\nparabolic flow profile, single vesicles migrate towards the center of the\nchannel, where they adopt symmetric shapes, for two reasons. First, walls exert\na hydrodynamic lift force which pushes them away. Second, shear stresses are\nminimal at the tip of the flow. However, symmetry is broken for vesicles with\nlarge excess areas, which flow off-center and deform asymmetrically. In\nsuspensions, hydrodynamic interactions between vesicles add up to these two\neffects, making it challenging to deduce rheological properties from the\ndynamics of individual vesicles. Further investigations of vesicles and similar\nobjects and their suspensions in steady or time-dependent flow will shed light\non phenomena such as blood flow."
    },
    {
        "anchor": "Patchy worm-like micelles: solution structure studied by small-angle\n  neutron scattering: Triblock terpolymers exhibit a rich self-organization behavior including the\nformation of fascinating cylindrical core-shell structures with a phase\nseparated corona. After crystallization-induced self-assembly of\npolystryrene-(block)-polyethylene-(block)-poly(methyl methacrylate) triblock\nterpolymers (abbreviated as SEMs = Styrene-Ethylene-Methacrylates) from\nsolution, worm-like core-shell micelles with a patchy corona of polystryrene\nand poly(methyl methacrylate) were observed by transmission electron\nmicroscopy. However, the solution structure is still a matter of debate. Here,\nwe present a method to distinguish in-situ between a Janus-type (two faced) and\na patchy (multiple compartments) configuration of the corona. To discriminate\nbetween both models the scattering intensity must be determined mainly by one\ncorona compartment. Contrast variation in small-angle neutron scattering\nenables us to focus on one compartment of the SEMs. The results validate the\nexistence of the patchy structure also in solution.",
        "positive": "Iontronic Neuromorphic Signaling with Conical Microfluidic Memristors: Experiments have shown that the conductance of conical channels, filled with\nan aqueous electrolyte, can strongly depend on the history of the applied\nvoltage. These channels hence have a memory and are promising elements in\nbrain-inspired (iontronic) circuits. We show here that the memory of such\nchannels stems from transient concentration polarization over the ionic\ndiffusion time. We derive an analytic approximation for these dynamics which\nshows good agreement with full finite-element calculations. Using our analytic\napproximation, we propose an experimentally realisable Hodgkin-Huxley iontronic\ncircuit where micrometer cones take on the role of sodium and potassium\nchannels. Our proposed circuit exhibits key features of neuronal communication\nsuch as all-or-none action potentials upon a pulse stimulus and a spike train\nupon a sustained stimulus."
    },
    {
        "anchor": "Diffusion in a Granular Fluid - Simulation: The linear response description for impurity diffusion in a granular fluid\nundergoing homogeneous cooling is developed in the preceeding paper. The\nformally exact Einstein and Green-Kubo expressions for the self-diffusion\ncoefficient are evaluated there from an approximation to the velocity\nautocorrelation function. These results are compared here to those from\nmolecular dynamics simulations over a wide range of density and inelasticity,\nfor the particular case of self-diffusion. It is found that the approximate\ntheory is in good agreement with simulation data up to moderate densities and\ndegrees of inelasticity. At higher density, the effects of inelasticity are\nstronger, leading to a significant enhancement of the diffusion coefficient\nover its value for elastic collisions. Possible explanations associated with an\nunstable long wavelength shear mode are explored, including the effects of\nstrong fluctuations and mode coupling.",
        "positive": "Detection of chiral domains and linear electro-optical response in\n  planar-aligned cells of an achiral rod-like ferro-electric nematic liquid\n  crystal: Chiral domains of opposite chirality are observed surprisingly in a nematic\nphase of an achiral rod-like liquid crystalline mesogen that shows\nferroelectric nematic and antiferroelectric smectic phases. The observations of\nchiral domains of opposite chirality are enabled by application of a weak\nelectric field across a planar-aligned cell. However once domains of opposite\nchirality are created, these stay permanently even if the field is removed. The\nobserved phenomenon is due to the symmetry breaking of achiral mesogens of\nrod-shaped molecules. These domains are similarly observed in the Nx phase.\nHowever for temperatures close or in the NF, the size of domains is reduced\nsignificantly below the wavelength of visible light. There is either a single\ndomain with dipole moments parallel to the surface or domains antiparallel in\nthe NF phase, not possible to determine in this experiment."
    },
    {
        "anchor": "Supercooled Liquids Under Shear: Theory and Simulation: We analyze the behavior of supercooled fluids under shear both theoretically\nand numerically. Theoretically, we generalize the mode-coupling theory of\nsupercooled fluids to systems under stationary shear flow. Our starting point\nis the set of generalized fluctuating hydrodynamic equations with a convection\nterm. A nonlinear integro-differential equation for the intermediate scattering\nfunction is constructed. This theory is applied to a two-dimensional colloidal\nsuspension. The shear rate dependence of the intermediate scattering function\nand the shear viscosity is analyzed. We have also performed extensive numerical\nsimulations of a two-dimensional binary liquid with soft-core interactions\nnear, but above, the glass transition temperature. Both theoretical and\nnumerical results show: (i) A drastic reduction of the structural relaxation\ntime and the shear viscosity due to shear. Both the structural relaxation time\nand the viscosity decrease as $\\dot{\\gamma}^{-\\nu}$ with an exponent $\\nu \\leq\n1$, where $\\dot{\\gamma}$ is the shear rate. (ii) Almost isotropic dynamics\nregardless of the strength of the anisotropic shear flow.",
        "positive": "A new universality class describes Vicsek's flocking phase in physical\n  dimensions: The Vicsek simulation model of flocking together with its theoretical\ntreatment by Toner and Tu in 1995 were two foundational cornerstones of active\nmatter physics. However, despite the field's tremendous progress, the actual\nuniversality class (UC) governing the scaling behavior of Viscek's \"flocking\"\nphase remains elusive. Here, we use nonperturbative, functional renormalization\ngroup methods to analyze, numerically and analytically, a simplified version of\nthe Toner-Tu model, and uncover a novel UC with scaling exponents that agree\nremarkably well with the values obtained in a recent simulation study by\nMahault et al. [Phys. Rev. Lett. 123, 218001 (2019)], in both two and three\nspatial dimensions. We therefore believe that there is strong evidence that the\nUC uncovered here describes Vicsek's flocking phase."
    },
    {
        "anchor": "Morphogenesis and self-organization of persistent filaments confined\n  within flexible biopolymeric shells: We systematically explore the self-assembly of semi-flexible polymers in\ndeformable spherical confinement across a wide regime of chain stiffness,\ncontour lengths and packing fractions by means of coarse-grained molecular\ndynamics simulations. Compliant, DNA-like filaments are found to undergo a\ncontinuous crossover from two distinct surface-ordered quadrupolar states, both\ncharacterized by tetrahedral patterns of topological defects, to either\nlongitudinal or latitudinal bipolar structures with increasing polymer\nconcentrations. These transitions, along with the intermediary arrangements\nthat they involve, may be attributed to the combination of an orientational\nwetting phenomenon with subtle density- and contour-length-dependent variations\nin the elastic anisotropies of the corresponding liquid crystal phases.\nConversely, the organization of rigid, microtubule-like polymers evidences a\nprogressive breakdown of continuum elasticity theory as chain dimensions become\ncomparable to the equilibrium radius of the encapsulating membrane. In this\ncase, we observe a gradual shift from prolate, tactoid-like morphologies to\noblate, erythrocyte-like structures with increasing contour lengths, which is\nshown to arise from the interplay between nematic ordering, polymer and\nmembrane buckling. We further provide numerical evidence of a number of\nyet-unidentified, self-organized states in such confined systems of stiff\nachiral filaments, including spontaneous spiral smectic assemblies, faceted\npolyhedral and twisted bundle-like arrangements. Our results are quantified\nthrough the introduction of several order parameters and an unsupervised\nlearning scheme for the localization of surface topological defects, and are in\nexcellent agreement with field-theoretical predictions as well as classical\nelastic theories of thin rods and spherical shells.",
        "positive": "Transport Phenomena and Structuring in Shear Flow of Suspensions near\n  Solid Walls: In this paper we apply the lattice-Boltzmann method and an extension to\nparticle suspensions as introduced by Ladd et al. to study transport phenomena\nand structuring effects of particles suspended in a fluid near sheared solid\nwalls. We find that a particle free region arises near walls, which has a width\ndepending on the shear rate and the particle concentration. The wall causes the\nformation of parallel particle layers at low concentrations, where the number\nof particles per layer decreases with increasing distance to the wall."
    },
    {
        "anchor": "Magnetization and susceptibility of polydisperse ferrofluids: On the basis of the mean spherical approximation of multicomponent dipolar\nhard sphere mixtures an analytical expression is proposed for the magnetic\nfield dependence of the magnetization of size polydisperse ferrofluids. The\npolydispersity of the particle diameter is described by the gamma distribution\nfunction. Canonical ensemble Monte Carlo simulations have been performed in\norder to test these theoretical results for the initial susceptibility and the\nmagnetization. The results for the magnetic properties of the polydisperse\nsystems turn out to be in quantitative agreement with our present simulation\ndata. In addition, we find good agreement between our theory and experimental\ndata for magnetite-based ferrofluids.",
        "positive": "On the colloidal stability of apolar nanoparticles: The role of ligand\n  length: Inorganic nanoparticle cores are often coated with organic ligands to render\nthem dispersible in apolar solvents. However, the effect of the ligand shell on\nthe colloidal stability of the overall hybrid particle is not fully understood.\nIn particular, it is not known how the length of an apolar alkyl ligand chain\naffects the stability of a nanoparticle dispersion against agglomeration. Here,\nSmall-Angle X-ray Scattering and molecular dynamics simulations have been used\nto study the interactions between gold nanoparticles and between cadmium\nselenide nanoparticles passivated by alkanethiol ligands with 12 to 18 carbons\nin the solvent decane. We find that increasing the ligand length increases\ncolloidal stability in the core-dominated regime but decreases it in the\nligand-dominated regime. This unexpected inversion is connected to the\ntransition from ligand- to core-dominated agglomeration when the core diameter\nincreases at constant ligand length. Our results provide a microscopic picture\nof the forces that determine the colloidal stability of apolar nanoparticles\nand explain why classical colloid theory fails."
    },
    {
        "anchor": "Microstructured superhydrorepellent surfaces: Effect of drop pressure on\n  fakir-state stability and apparent contact angles: In this paper we present a generalized Cassi-Baxter equation to take into\naccount the effect of drop pressure on the apparent contact angle theta_{app}.\nAlso we determine the limiting pressure p_{W} which causes the impalement\ntransition to the Wenzel state and the pull-off pressure p_{out} at which the\ndrop detaches from the substrate. The calculations have been carried out for\naxial-symmetric pillars of three different shapes: conical, hemispherical\ntopped and flat topped cylindrical pillars. Calculations show that, assuming\nthe same pillar spacing, conical pillars may be more incline to undergo an\nimpalement transition to the Wenzel state, but, on the other hand, they are\ncharacterized by a vanishing pull-off pressure which causes the drop not to\nadhere to the substrate and therefore to detach very easily. We infer that this\nproperty should strongly reduce the contact angle hysteresis as experimentally\nosberved in Ref. \\cite{Martines-Conical-Shape}. It is possible to combine large\nresistance to impalement transition (i.e. large value of p_{W}) and small (or\neven vanishing) detaching pressure p_{out} by employing cylindrical pillars\nwith conical tips. We also show that depending on the particular pillar\ngeometry, the effect of drop pressure on the apparent contact angle theta_{app}\nmay be more or less significant. In particular we show that in case of conical\npillars increasing the drop pressure causes a significant decrease of\ntheta_{app} in agreement with some experimental investigations\n\\cite{LafunaTransitio}, whereas theta_{app} slightly increases for\nhemispherical or flat topped cylindrical pillars.",
        "positive": "Distribution of lipids in non-lamellar phases of their mixtures: We consider a model of lipids in which a head group, characterized by its\nvolume, is attached to two flexible tails of equal length. The phase diagram of\nthe anhydrous lipid is obtained within self-consistent field theory, and\ndisplays, as a function of lipid architecture, a progression of phases:\nbody-centered cubic, hexagonal, gyroid, and lamellar. We then examine mixtures\nof an inverted hexagonal forming lipid and a lamellar forming lipid. As the\nvolume fractions of the two lipids vary, we find that inverted hexagonal,\ngyroid, or lamellar phases are formed. We demonstrate that the non-lamellar\nforming lipid is found preferentially at locations which are difficult for the\nlipid tails to reach. Variations in the volume fraction of each type of lipid\ntail are on the order of one to ten per cent within regions dominated by the\ntails. We also show that the variation in volume fraction is correlated\nqualitatively with the variation in mean curvature of the head-tail interface."
    },
    {
        "anchor": "Three-dimensional crystals of adaptive knots: Starting from Gauss and Kelvin, knots in fields were postulated behaving like\nparticles, but experimentally they were found only as transient features or\nrequired complex boundary conditions to exist and couldn't self-assemble into\nthree-dimensional crystals. We introduce energetically stable micrometer-sized\nknots in helical fields of chiral liquid crystals. While spatially localized\nand freely diffusing in all directions, they resemble colloidal particles and\natoms, self-assembling into crystalline lattices with open and closed\nstructures. These knots are robust and topologically distinct from the host\nmedium, though they can be morphed and reconfigured by weak stimuli under\nconditions like in displays. A combination of energy-minimizing numerical\nmodeling and optical imaging uncovers the internal structure and topology of\nindividual helical field knots and various hierarchical crystalline\norganizations they form.",
        "positive": "Topological Boundary Constraints in Artificial Colloidal Ice: The effect of boundaries and how these can be used to influence the bulk\nbehaviour in geometrically frustrated systems are both long-standing puzzles,\noften relegated to secondary role. Here we use numerical simulations and \"proof\nof concept\" experiments to demonstrate that boundaries can be engineered to\ncontrol the bulk behavior in a colloidal artificial ice. We show that an\nantiferromagnetic frontier forces the system to rapidly reach the ground state\n(GS), as opposed to the commonly implemented open or periodic boundary\nconditions. We also show that strategically placing defects at the corners\ngenerates novel bistable states, or topological strings which result from\ncompeting GS regions in the bulk. Our results could be generalized to other\nfrustrated micro and nanostructures where boundary conditions may be engineered\nwith lithographic techniques."
    },
    {
        "anchor": "Bending Moduli of Charged Membranes Immersed in Polyelectrolyte\n  Solutions: We study the contribution of polyelectrolytes in solution to the bending\nmoduli of charged membranes. Using the Helfrich free energy, and within the\nmean-field theory, we calculate the dependence of the bending moduli on the\nelectrostatics and short-range interactions between the membrane and the\npolyelectrolyte chains. The most significant effect is seen for strong\nshort-range interactions and low amounts of added salt where a substantial\nincrease in the bending moduli of order $1 k_BT$ is obtained. From short-range\nrepulsive membranes, the polyelectrolyte contribution to the bending moduli is\nsmall, of order $0.1 k_BT$ up to at most $1 k_BT$. For weak short-range\nattraction, the increase in membrane rigidity is smaller and of less\nsignificance. It may even become negative for large enough amounts of added\nsalt. Our numerical results are obtained by solving the adsorption problem in\nspherical and cylindrical geometries. In some cases the bending moduli are\nshown to follow simple scaling laws.",
        "positive": "Simulation of Interdiffusion in Between Compartments Having\n  Heterogenously Distributed Donors and Acceptors: The final stage of latex film formation was simulated by introducing donors\nand acceptors into the adjacent compartments of a cube. Homogenous and/or\nheterogeneous donor-acceptor distributions were chosen for different types of\nsimulations. The interdiffusion of the donors and the acceptors within these\ncubes was generated using the Monte-Carlo technique. The decay of the donor\nintensity I(t) by direct energy transfer (DET) was simulated for several\ninterdiffusion steps. Gaussian noise was added to the I(t) curves to obtain\nmore realistic decay profiles. I(t) decay curves were fitted to the\nphenomenological equation to calculate the fractional mixing at each\ninterdiffusion step. The reliability of the Fickian diffusion model in the case\nof heterogenous and homogeneous donor-acceptor distributions are discussed for\nlatex film formation."
    },
    {
        "anchor": "Lattice Boltzmann kinetic modeling and simulation of thermal\n  liquid-vapor system: We present a highly efficient lattice Boltzmann (LB) kinetic model for\nthermal liquid-vapor system. Three key components are as beow: (i) a discrete\nvelocity model by Kataoka \\emph{et al.} [Phys. Rev. E \\textbf{69},\n035701(R)(2004)]; (ii) a forcing term $I_{i}$ aiming to describe the\ninterfacial stress and recover the van der Waals equation of state by Gonnella\n\\emph{et al.} [Phys. Rev. E \\textbf{76}, 036703 (2007)]; and (iii) a Windowed\nFast Fourier Transform (WFFT) scheme and its inverse by our group [Phys. Rev. E\n\\textbf{84}, 046715 (2011)] for solving the spatial derivatives, together with\na second-order Runge-Kutta (RK) finite difference scheme for solving the\ntemporal derivative in the LB equation. The model is verified and validated by\nwell-known benchmark tests. The results recovered from the present model are\nwell consistent with previous ones[Phys. Rev. E \\textbf{84}, 046715 (2011)] or\ntheoretical analysis. The usage of less discrete velocities, high-order RK\nalgorithm and WFFT scheme with 16th-order in precision makes the model more\nefficient by about $10$ times and more accurate than the original one.",
        "positive": "Viscoelasticity of 2D liquids quantified in a dusty plasma experiment: The viscoelasticity of two-dimensional liquids is quantified in an experiment\nusing a dusty plasma. An experimental method is demonstrated for measuring the\nwavenumber-dependent viscosity, $\\eta(k)$, which is a quantitative indicator of\nviscoelasticity. Using an expression generalized here to include friction,\n$\\eta(k)$ is computed from the transverse current autocorrelation function\n(TCAF), which is found by tracking random particle motion. The TCAF exhibits an\noscillation that is a signature of elastic contributions to viscoelasticity.\nSimulations of a Yukawa liquid are consistent with the experiment."
    },
    {
        "anchor": "Third- and fourth-order elasticity of biological soft tissues: In the theory of weakly non-linear elasticity, Hamilton et al. [J. Acoust.\nSoc. Am. \\textbf{116} (2004) 41] identified $W = \\mu I_2 + (A/3)I_3 + D I_2^2$\nas the fourth-order expansion of the strain-energy density for incompressible\nisotropic solids. Subsequently, much effort focused on theoretical and\nexperimental developments linked to this expression in order to inform the\nmodeling of gels and soft biological tissues. However, while many soft tissues\ncan be treated as incompressible, they are not in general isotropic, and their\nanisotropy is associated with the presence of oriented collagen fiber bundles.\nHere the expansion of $W$ is carried up to fourth-order in the case where there\nexists one family of parallel fibers in the tissue. The results are then\napplied to acoustoelasticity, with a view to determining the second- and\nthird-order nonlinear constants by employing small-amplitude transverse waves\npropagating in a deformed soft tissue.",
        "positive": "Relative Entropy of a Freely Cooling Granular Gas: The time evolution and stationary values of the entropy per particle of a\nhomogeneous freely cooling granular gas, relative to the maximum entropy\nconsistent with the instantaneous translational and rotational temperatures, is\nanalyzed by means of a Sonine approximation involving fourth-degree cumulants.\nThe results show a rich variety of dependencies of the relative entropy on time\nand on the coefficients of normal and tangential restitution, including a\npeculiar behavior in the quasi-smooth limit."
    },
    {
        "anchor": "Two-dimensional loosely and tightly bound solitons in optical lattices\n  and inverted traps: We study the dynamics of nonlinear localized excitations (solitons) in\ntwo-dimensional (2D) Bose-Einstein condensates (BECs) with repulsive\ninteractions, loaded into an optical lattice (OL), which is combined with an\nexternal parabolic potential. First, we demonstrate analytically that a broad\n(loosely bound, LB) soliton state, based on a 2D Bloch function near the edge\nof the Brillouin zone (BZ), has a negative effective mass (while the mass of a\nlocalized state is positive near the BZ center). The negative-mass soliton\ncannot be held by the usual trap, but it is safely confined by an inverted\nparabolic potential (anti-trap). Direct simulations demonstrate that the LB\nsolitons (including the ones with intrinsic vorticity) are stable and can\nfreely move on top of the OL. The frequency of elliptic motion of the\nLB-soliton's center in the anti-trapping potential is very close to the\nanalytical prediction which treats the solition as a quasi-particle. In\naddition, the LB soliton of the vortex type features real rotation around its\ncenter. We also find an abrupt transition, which occurs with the increase of\nthe number of atoms, from the negative-mass LB states to tightly bound (TB)\nsolitons. An estimate demonstrates that, for the zero-vorticity states, the\ntransition occurs when the number of atoms attains a critical number N=10^3,\nwhile for the vortex the transition takes place at N=5x10^3 atoms. The\npositive-mass LB states constructed near the BZ center (including vortices) can\nmove freely too. The effects predicted for BECs also apply to optical spatial\nsolitons in bulk photonic crystals.",
        "positive": "Self-assembly of repulsive interfacial particles via collective sinking: Charged colloidal particles trapped at an air--water interface are well known\nto form an ordered crystal, stabilized by a long ranged repulsion, the details\nof this repulsion remain something of a mystery, but all experiments performed\nto date have confirmed a dipolar-repulsion, at least at dilute concentrations.\nMore complex arrangements are often observed, especially at higher\nconcentration, and these seem to be incompatible with a purely repulsive\npotential. In addition to electrostatic repulsion, interfacial particles may\nalso interact via deformation of the surface: so-called capillary effects.\nPair-wise capillary interactions are well understood, and are known to be too\nsmall (for these colloidal particles) to overcome thermal effects. Here we show\nthat collective effects may significantly modify the simple pair-wise\ninteractions and become important at higher density, though we remain well\nbelow close packing throughout. In particular, we show that the interaction of\nmany interfacial particles can cause much larger interfacial deformations than\ndo isolated particles, and show that the energy of interaction per particle due\nto this \"collective sinking\" grows as the number of interacting particles\ngrows. Though some of the parameters in our simple model are unknown, the\nscaling behaviour is entirely consistent with experimental data, strongly\nindicating that estimating interaction energy based solely on pair-wise\npotentials may be too simplistic for surface particle layers."
    },
    {
        "anchor": "Stable freestanding thin films of copolymer melts far from the glass\n  transition: Thin polymer films have attracted attention because of both their broad range\nof applications and of the fundamental questions they raise regarding the\ndynamic response of confined polymers. These films are unstable if the\ntemperature is above their glass transition temperature Tg. Here, we describe\nfreestanding thin films of centimetric dimensions made of a comb copolymer melt\nfar from its glass transition that are stable for more than a day. These long\nlifetimes allowed us to characterize the drainage dynamics and the thickness\nprofile of the films. Stratified regions appear as the film drains. We have\nevidence that the stability, thinning dynamics and thickness profile of the\nfilms result from structural forces in the melt. Understanding the key\nmechanisms behind our observations may lead to new developments in polymeric\nthin films, foams and emulsions without the use of stabilizing agents.",
        "positive": "Low-entangled UHMWPE melt: analytical model and computer simulations: In this work we developed a theoretical model to describe the polymerization\nof very long macromolecules with simultaneous precipitation. As a reference\nsystem for our model we consider UHMWPE polymerization process, via homogeneous\ncatalysis and with molecular weight above $10^6$ monomers. We derived time\ndependency of the entanglement length in the system, and assessed how\npolymerization rate and fraction of initiators affects this dependency. We show\nthat decrease of the fraction of initiators leads to increase of the average\nentanglement length in the melt after complete polymerization. The results are\nsupported by computer simulations and in principle could be applied to the wide\nset of polymerized materials, both crystallized and amorphous."
    },
    {
        "anchor": "Quasielastic small-angle neutron scattering from heavy water solutions\n  of cyclodextrins: We present a model for quasielastic neutron scattering (QENS) by an aqueous\nsolution of compact and inflexible molecules. This model accounts for\ntime-dependent spatial pair correlations between the atoms of the same as well\nas of distinct molecules and includes all coherent and incoherent neutron\nscattering contributions. The extension of the static theory of the excluded\nvolume effect [A. K. Soper, J. Phys.:Condens. Matter 9, 2399 (1997)] to the\ntime-dependent (dynamic) case allows us to obtain simplified model expressions\nfor QENS spectra in the low Q region in the uniform fluid approximation. The\nresulting expressions describe the quasielastic small-angle neutron scattering\n(QESANS) spectra of D2O solutions of native and methylated cyclodextrins well,\nyielding in particular translational and rotational diffusion coefficients of\nthese compounds in aqueous solution. Finally, we discuss the full potential of\nthe QESANS analysis (that is, beyond the uniform fluid approximation), in\nparticular, the information on solute-solvent interactions (e.g., hydration\nshell properties) that such an analysis can provide, in principle.",
        "positive": "Differential Dynamic Microscopy microrheology of soft materials: a\n  tracking-free determination of the frequency-dependent loss and storage\n  moduli: Particle tracking microrheology (PT-$\\mu$r) exploits the thermal motion of\nembedded particles to probe the local mechanical properties of soft materials.\nDespite its appealing conceptual simplicity, PT-$\\mu$r requires calibration\nprocedures and operating assumptions that constitute a practical barrier to a\nwider adoption. Here we demonstrate Differential Dynamic Microscopy\nmicrorheology (DDM-$\\mu$r), a tracking-free approach based on the multi-scale,\ntemporal correlation study of the image intensity fluctuations that are\nobserved in microscopy experiments as a consequence of the motion of the\ntracers. We show that the mechanical moduli of an arbitrary sample are\ndetermined correctly in a wide frequency range, provided that the standard DDM\nanalysis is reinforced with a novel, iterative, self-consistent procedure that\nfully exploits the multi-scale information made available by DDM. Our approach\nto DDM-$\\mu$r does not require any prior calibration, is in agreement with both\ntraditional rheology and Diffusing Wave Spectroscopy microrheology, and works\nin conditions where PT-$\\mu$r fails, providing thus an operationally simple,\ncalibration-free probe of soft materials."
    },
    {
        "anchor": "Phase equilibria and charge fractionation in polydisperse\n  polyelectrolyte solutions: A new type of phase separation in the polyelectrolyte solutions consisting of\nseveral types of charged macromolecules differing in their degree of ionization\nis predicted via a general thermodynamic consideration. We show that even a\nsmall difference in the degree of ionization of otherwise equivalent components\nresults in their spatial separation occurring upon decreasing the temperature\nmuch earlier than precipitation of the components from the solution. Some\nimplications of charge fractionation in biological processes are discussed.",
        "positive": "Marginally compact hyperbranched polymer trees: Assuming Gaussian chain statistics along the chain contour, we generate by\nmeans of a proper fractal generator hyperbranched polymer trees which are\nmarginally compact. Static and dynamical properties, such as the radial\nintrachain pair density distribution or the shear-stress relaxation modulus,\nare investigated theoretically and by means of computer simulations. We\nemphasize that albeit the self-contact density diverges logarithmically with\nthe total mass $N$, this effect becomes rapidly irrelevant with increasing\nspacer length $S$. In addition to this it is seen that the standard Rouse\nanalysis must necessarily become inappropriate for compact objects for which\nthe relaxation time $\\tau_p$ of mode $p$ must scale as $\\tau_p \\sim\n(N/p)^{5/3}$ rather than the usual square power law for linear chains."
    },
    {
        "anchor": "Buckling in Armored Droplets: The issue of the buckling mechanism in droplets stabilized by solid particles\n(armored droplets) is tackled at a mesoscopic level using dissipative particle\ndynamics simulations. We consider spherical water droplet in a decane solvent\ncoated with nanoparticle monolayers of two different types: Janus and\nhomogeneous. The chosen particles yield comparable initial three-phase contact\nangles, chosen to maximize the adsorption energy at the interface. We study the\ninterplay between the evolution of droplet shape, layering of the particles,\nand their distribution at the interface when the volume of the droplets is\nreduced. We show that Janus particles affect strongly the shape of the droplet\nwith the formation of a crater-like depression. This evolution is actively\ncontrolled by a close-packed particle monolayer at the curved interface. On the\ncontrary, homogeneous particles follow passively the volume reduction of the\ndroplet, whose shape does not deviate too much from spherical, even when a\nnanoparticle monolayer/bilayer transition is detected at the interface. We\ndiscuss how these buckled armored droplets might be of relevance in various\napplications including potential drug delivery systems and biomimetic design of\nfunctional surfaces.",
        "positive": "Percolation line, response functions, and Voronoi polyhedra analysis in\n  supercritical water: The problem of a physical relevance (meaning) of percolation in supercritical\nfluids is addressed considering a primitive model of water. Two different\ncriteria, physical and configurational, are used for the cluster definition in\nMonte Carlo simulations over a range of pressures to determine the percolation\nline and skewness, and a theoretical analytic equation of state is used to\nevaluate response functions. It is found that both criteria yield practically\nthe same percolation line. However, unlike the findings for simple fluids, the\nloci of the response function extrema exhibit density/pressure dependence quite\ndifferent from that of the percolation line. The only potential coincidence\nbetween the loci of the extrema of a thermodynamic property and a detectable\nstructural change is found for the coefficient of isothermal compressibility\nand Voronoi neighbors distribution skewness maximum."
    },
    {
        "anchor": "Rivalry of diffusion, external field and gravity in micro-convection of\n  magnetic colloids: Magnetic fields and magnetic materials have promising microfluidic\napplications. For example, magnetic micro-convection can enhance mixing\nconsiderably. However, previous studies have not explained increased effective\ndiffusion during this phenomenon. Here we show that enhanced interface smearing\ncomes from a gravity induced convective motion within a thin microfluidic\nchannel, caused by a small density difference between miscible magnetic and\nnon-magnetic fluids. This motion resembles diffusive behavior and can be\ndescribed with an effective diffusion coefficient. We explain this with a\ntheoretical model, based on a dimensionless gravitational Rayleigh number, and\nverify it by numerical simulations and experiments with different cell\nthicknesses. Results indicate the applicability and limitations for\nmicrofluidic applications of other colloidal systems. Residual magnetic\nmicro-convection follows earlier predictions.",
        "positive": "On the choice of diameters in a polydisperse model glassformer:\n  deterministic or stochastic?: In particle-based computer simulations of polydisperse glassforming systems,\nthe particle diameters $\\sigma = \\sigma_1, \\dots, \\sigma_N$ of a system with\n$N$ particles are chosen with the intention to approximate a desired\ndistribution density $f$ with the corresponding histogram. One method to\naccomplish this is to draw each diameter randomly from the density $f$. We\nrefer to this stochastic scheme as model $\\mathcal{S}$. Alternatively, one can\napply a deterministic method, assigning an appropriate set of $N$ values to the\ndiameters. We refer to this method as model $\\mathcal{D}$. We show that\nespecially for the glassy dynamics at low temperatures it matters whether one\nchooses model $\\mathcal{S}$ or model $\\mathcal{D}$. Using molecular dynamics\ncomputer simulation, we investigate a three-dimensional polydisperse\nnon-additive soft-sphere system with $f(s) \\sim s^{-3}$. The Swap Monte Carlo\nmethod is employed to obtain equilibrated samples at very low temperatures. We\nshow that for model $\\mathcal{S}$ the sample-to-sample fluctuations due to the\nquenched disorder imposed by the diameters $\\sigma$ can be explained by an\neffective packing fraction. Dynamic susceptibilities in model $\\mathcal{S}$ can\nbe split into two terms: One that is of thermal nature and can be identified\nwith the susceptibility of model $\\mathcal{D}$, and another one originating\nfrom the disorder in $\\sigma$. At low temperatures the latter contribution is\nthe dominating term in the dynamic susceptibility."
    },
    {
        "anchor": "Transition of defect patterns from 2D to 3D in liquid crystals: Defects arise when nematic liquid crystals are under topological constraints\nat the boundary. Recently the study of defects has drawn a lot of attention. In\nthis paper, we investigate the relationship between two-dimensional defects and\nthree-dimensional defects within nematic liquid crystals confined in a shell\nunder the Landau-de Gennes model. We use a highly accurate spectral method to\nnumerically solve the Landau- de Gennes model to get the detailed static\nstructures of defects. Interestingly, the solution is radial-invariant when the\nthickness of the shell is sufficiently small. As the shell thickness increase,\nthe solution undergo symmetry break to reconfigure the disclination lines. We\nstudy this three-dimensional reconfiguration of disclination lines in detail\nunder different boundary conditions. We also discuss the topological charge of\ndefects in two- and three-dimensional spaces within the tensor model.",
        "positive": "Boundary Element Method for non-adhesive and adhesive contacts of a\n  coated elastic half-space: We present a new formulation of the Boundary Element Method (BEM) for\nsimulating the non-adhesive and adhesive contact between an indenter of\narbitrary shape and an elastic half-space coated with an elastic layer of\ndifferent material. We use the Fast Fourier Transform based formulation of BEM,\nwhile the fundamental solution is determined directly in the Fourier space.\nNumerical tests are validated by comparison with available asymptotic\nanalytical solutions for axisymmetric flat and spherical indenter shapes."
    },
    {
        "anchor": "Optimal transport and control of active drops: Understanding the complex patterns in space-time exhibited by active systems\nhas been the subject of much interest in recent times. Complementing this\nforward problem is the inverse problem of controlling active matter. Here we\nuse optimal control theory to pose the problem of transporting a slender drop\nof an active fluid and determine the dynamical profile of the active stresses\nto move it with minimal viscous dissipation. By parametrizing the position and\nsize of the drop using a low-order description based on lubrication theory, we\nuncover a natural ''gather-move-spread'' strategy that leads to an optimal\nbound on the maximum achievable displacement of the drop relative to its size.\nIn the continuum setting, the competition between passive surface tension, and\nactive controls generates richer behaviour with futile oscillations and complex\ndrop morphologies that trade internal dissipation against the transport cost to\nselect optimal strategies. Our work combines active hydrodynamics and optimal\ncontrol in a tractable and interpretable framework, and begins to pave the way\nfor the spatiotemporal manipulation of active matter.",
        "positive": "Effect of molecular structure of eco-friendly glycolipid biosurfactants\n  on the adsorption of hair-care conditioning polymers: Pseudo-binary mixtures of different glycolipids, four different rhamnolipids\n(RL) and an alkyl polyglucoside (APG), with poly(diallyl-dimethylammonium\nchloride) (PDADMAC) have been studied in relation to their adsorption onto\nnegatively charged surfaces to shed light on the impact of the molecular\nstructure of biodegradable surfactants from natural sources (instead of\nsynthetic surfactant, such as sodium laureth sulfate) on the adsorption of\nhair-care formulations. For this purpose, the self-assembly of such mixtures in\naqueous solution and their adsorption onto negatively charged surfaces\nmimicking the negative charge of damaged hair fibres have been studied using\nexperiments and self-consistent field (SCF) calculations. The results show that\nthe specific physico-chemical properties of the surfactants (charge, number of\nsugar rings present in surfactant structure and length of the hydrocarbon\nlength) play a main role in the control of the adsorption process, with the\nadsorption efficiency and hydration being improved in relation to conventional\nsulfate-based systems for mixtures of PDADMAC and glycolipids with the shortest\nalkyl chains. SCF calculations and Energy Dispersive X-Ray Spectroscopy (EDS)\nanalysis on real hair confirmed such observations. The results allow one to\nassume that the characteristic of the studied surfactants, especially\nrhamnolipids, conditions positively the adsorption potential of\npolyelectrolytes in our model systems. This study provides important insights\non the mechanisms underlying the performance of more complex but natural and\neco-friendly washing formulations."
    },
    {
        "anchor": "Langevin Dynamics of a Polymer with Internal Distance Constraints: We present a novel and rigorous approach to the Langevin dynamics of ideal\npolymer chains subject to internal distance constraints. The permanent\nconstraints are modelled by harmonic potentials in the limit when the strength\nof the potential approaches infinity (hard crosslinks). The crosslinks are\nassumed to exist between arbitrary pairs of monomers. Formally exact\nexpressions for the resolvent and spectral density matrix of the system are\nderived. To illustrate the method we study the diffusional behavior of monomers\nin the vicinity of a single crosslink within the framework of the Rouse model.\nThe same problem has been studied previously by Warner (J. Phys. C: Solid State\nPhys. {\\bf 14}, 4985, (1981)) on the basis of Lagrangian multipliers. Here we\nderive the full, hence exact, solution to the problem.",
        "positive": "Controlled release of entrapped nanoparticles from thermoresponsive\n  hydrogels with tunable network characteristics: Thermoresponsive hydrogels have been studied intensively for creating smart\ndrug carriers and controlled drug delivery. Understanding the drug release\nkinetics and corresponding transport mechanisms of nanoparticles (NPs) in a\nthermoresponsive hydrogel network is the key to the successful design of a\nsmart drug delivery system. We construct a mesoscopic model of rigid NPs\nentrapped in a hydrogel network in an aqueous solution, where the hydrogel\nnetwork is formed by cross-linked semiflexible polymers of PNIPAM. By varying\nthe environmental temperature crossing the lower critical solution temperature\nof PNIPAM we can significantly change the hydrogel network characteristics. We\nsystematically investigate how the matrix porosity and the nanoparticle size\naffect the NPs' transport kinetics at different temperatures. Quantitative\nresults on the mean-squared displacement and the van Hove displacement\ndistributions of NPs show that all NPs entrapped in the smart hydrogels undergo\nsubdiffusion at both low and high temperatures. For a coil state, the\nsubdiffusive exponent and the diffusion coefficient of NPs increase due to the\nincreased kinetic energy and the decreased confinement on NPs, while the\ntransport of NPs in the hydrogels can be also enhanced by decreasing the matrix\nporosity and NPs' size. However, when the solution temperature is increased\nabove the critical temperature, the hydrogel network collapses following the\ncoil-to-globule transition, with the NPs tightly trapped in some local regions\ninside the hydrogels. Consequently, the NP diffusion coefficient can be reduced\nby two orders of magnitude, or the diffusion processes can even be completely\nstopped. These findings provide new insights for designing controlled drug\nrelease from stimuli-responsive hydrogels, including autonomously switch on/off\ndrug release to respond to the changes of the local environment."
    },
    {
        "anchor": "From boiling point to glass transition temperature: transport\n  coefficients in molecular liquids follow three-parameter scaling: The phenomenon of the glass transition is an unresolved problem of condensed\nmatter physics. Its prominent feature, the super-Arrhenius temperature\ndependence of the transport coefficients remains a challenge to be described\nover the full temperature range. For a series of molecular glass formers, we\ncombined tau(T) from dielectric spectroscopy and dynamic light scattering\ncovering the range 10_-12 s < tau(T) < 10^2s. Describing the dynamics in terms\nof an activation energy E(T), we distinguish a high-temperature regime\ncharacterized by an Arrhenius law with a constant activation energy E_inf and a\nlow-temperature regime for which E_coop(T):= E(T) - E_inf increases while\ncooling. A two-parameter scaling is introduced, specifically E_coop(T)/E_inf =\nf[lambda(T/T_A -1)], where f is an exponential function, lambda a dimensionless\nparameter, and T_A a reference temperature proportional to E_inf. In order to\ndescribe tau(T), in addition, the attempt time tau_inf has to be specified.\nThus, a single interaction parameter E_inf extracted from the high-temperature\nregime together with lambda controls the temperature dependence of\nlow-temperature cooperative dynamics.",
        "positive": "Systematic derivation of hydrodynamic equations for viscoelastic phase\n  separation: (abridged) We present a detailed derivation of a simple hydrodynamic\ntwo-fluid model, which aims at the description of the phase separation of\nnon-entangled polymer solutions, where viscoelastic effects play a role. It is\ndirectly based upon the coarse-graining of a well-defined molecular model, such\nthat all degrees of freedom have a clear and unambiguous molecular\ninterpretation. The considerations are based upon a free-energy functional, and\nthe dynamics is split into a conservative and a dissipative part, where the\nlatter satisfies the Onsager relations and the Second Law of thermodynamics.\nThe model is therefore fully consistent with both equilibrium and\nnon-equilibrium thermodynamics. The derivation proceeds in two steps: Firstly,\nwe derive an extended model comprising two scalar and four vector fields, such\nthat inertial dynamics of the macromolecules and of the relative motion of the\ntwo fluids is taken into account. In the second step, we eliminate these\ninertial contributions and, as a replacement, introduce phenomenological\ndissipative terms, which can be modeled easily by taking into account the\nprinciples of non-equilibrium thermodynamics. The final simplified model\ncomprises the momentum conservation equation, which includes both interfacial\nand elastic stresses, a convection-diffusion equation where interfacial and\nelastic contributions occur as well, and a suitably convected relaxation\nequation for the end-to-end vector field. In contrast to the traditional\ntwo-scale description that is used to derive rheological equations of motion,\nwe here treat the hydrodynamic and the macromolecular degrees of freedom on the\nsame basis. Nevertheless, the resulting model is fairly similar, though not\nfully identical, to models that have been discussed previously. Notably, we\nfind a rheological constitutive equation that differs from the standard\nOldroyd-B model. ..."
    },
    {
        "anchor": "Stress phase space for static granular matter: This paper proposes a phase space to compare the static packings of a\ngranular system compatible to a macrostate that is set by the external stress.\nThe nature of this phase space is analyzed, showing that the consideration of\nthe allowed and forbidden regions and the internal degrees of freedom of every\nconfiguration (i.e. geometrical pattern) could be a relevant factor for the\nestablishment of its probability and, therefore, of the expected properties of\nthe sample. This is due to the fact that many combinations of forces acting on\na particle can keep it in static equilibrium. Every set of forces can be\nconsidered equivalent to a microscopic stress field, but the kind of\ninteraction and the geometrical restrictions mean that not all stress states\ncan be represented by any set, whereas others can be represented by many sets.\nConsequently the points of the phase space are degenerate, and the density of\nstates of each configuration strongly determines the most probable statistical\ndistribution. It is shown how these functions just depend on the deviatoric\nstress. A first analysis of two-dimensional (2D) arrangements is included to\nclarify this assertion.",
        "positive": "On the cavity evolution and the Rayleigh--Plesset equation in superfluid\n  helium: On the basis of the two-fluid hydrodynamics, an analogue of the famous\nRayleigh-Plesse equation for the dynamics of a spherical bubble in superfluid\nhelium is obtained. The mass flow velocity $v$ and the velocity of the normal\ncomponent $v_{n}$ were chosen as independent variables. Due to the two-fluid\nnature of HeII, the cross terms in the evolution equation for the boundary\nposition $\\ R(t)$ appeared, which were absent in classical Rayleigh-Plesset\nequation in ordinary fluids. One of them renormilizes the coefficient in front\nof $(dR/dt)^{2}$. Another additional term formally coinciding with the viscous\nterm, describes the attenuation of the boundary oscillations. This\n\"extra-damping\" term, greatly exceeding the usual viscous term, leads to a\nsignificant difference in the dynamics of cavity compared to HeI. In\nparticular, this results in the interesting effect of abnormal suppression of\noscillations of the vapor--liquid boundary observed in many works. There is\nalso an additional term proportional to the squared velocity of the normal\ncomponent, which is independent of the derivative $dR/dt$, and can be included\nin the pressure drop. Its physical meaning is that it describes a \"Bernoulli\"\n-like pressure created by the flow of a normal component. The obtained result\ndeclares that some results on the dynamics of the cavity in superfluid helium\nshould be reviewed"
    },
    {
        "anchor": "Optimal energy-harvesting cycles for load-driven dielectric generators\n  in plane strain: The performances of energy harvesting generators based on dielectric\nelastomers are investigated. The configuration is of a thin dielectric film\ncoated by stretchable electrodes at both sides. The film is first stretched,\nthen charged and subsequently, afterwards it is released, and finally the\ncharge is harvested at a higher electric potential. The amount of energy\nextracted by this cycle is bounded by the electric breakdown and the ultimate\nstretch ratio of the film as well as by structural instabilities due to loss of\ntension. To identify the optimal cycle that complies with these limits we\nformulate a constraint optimization problem and solve it with a dedicated\nsolver for two typical classes of elastic dielectrics. As anticipated, we find\nthat the performance of the generator depends critically on the ultimate\nstretch ratio of the film. However, more surprising is our finding of a\nuniversal limit on the dielectric strength of the film beyond which the optimal\ncycle is independent of this parameter. Thus, we reveal that, regardless of how\nlarge the dielectric strength of the material is, there is an upper bound on\nthe amount of harvested energy that depends only on the ultimate stretch ratio.\nWe conclude the work with detailed calculations of the optimal cycles for two\ncommercially available elastic dielectrics.",
        "positive": "Models of fractional viscous stresses for incompressible materials: We present and review several models of fractional viscous stresses from the\nliterature, which generalise classical viscosity theories to fractional orders\nby replacing total strain derivatives in time with fractional time derivatives.\nWe also briefly introduce Prony-type approximations of these theories. Here we\ninvestigate the issues of material frame-indifference and thermodynamic\nconsistency for these models and find that on these bases, some are physically\nunacceptable. Next we study elementary shearing and tensile motions, observing\nthat some models are more convenient to use than others for the analysis of\ncreep and relaxation. Finally, we compute the incremental stresses due to\nsmall-amplitude wave propagation in a deformed material, with a view to\nestablish acousto-elastic formulas for prospective experimental calibrations."
    },
    {
        "anchor": "Renormalization Theory for the Self-Avoiding Polymerized Membranes: We prove the renormalizability of the generalized Edwards model for\nself-avoiding polymerized membranes. This is done by use of a short distance\nmultilocal operator product expansion, which extends the methods of local field\ntheories to a large class of models with non-local singular interactions. This\nensures the existence of scaling laws for crumpled self-avoiding membranes, and\nvalidates the direct renormalization method used for polymers and membranes.\nThis also provides a framework for explicit perturbative calculations. We\ndiscuss hyperscaling relations for the configuration exponent and contact\nexponents. We finally consider membranes with long range interactions and at\nthe Theta-point.",
        "positive": "What Promotes Smectic Order: Applying Mean Field Theory to the Ends: Not every particle that forms a nematic liquid crystal makes a smectic. The\nparticle tip is critical for this behaviour. Ellipsoids do not make a smectic,\nbut sphero-cylinders do. Similarly, only those N-CB alkylcyanobiphenyls with\nsufficiently long ($N\\ge 8$ carbons) alkane tails form smectics. We understand\nthe role of the particle tip in the smectic transition by means of a simple\ntwo-dimensional model. We model sphero-cylinders by \"boubas\" with rounded tips,\nand ellipsoids by \"kikis\" with pointed tips. The N-CB molecules are modelled by\na small body with a polymer tail. We find that rounded tips and longer polymer\ntails lead to a smectic at lower densities by making the space between layers\nless accessible, destabilizing the nematic."
    },
    {
        "anchor": "Multiple light scattering in anisotropic random media: In the last decade Diffusing Wave Spectroscopy (DWS) has emerged as a\npowerful tool to study turbid media. In this article we develop the formalism\nto describe light diffusion in general anisotropic turbid media. We give\nexplicit formulas to calculate the diffusion tensor and the dynamic absorption\ncoefficient, measured in DWS experiments. We apply our theory to uniaxial\nsystems, namely nematic liquid crystals, where light is scattered from thermal\nfluctuations of the local optical axis, called director. We perform a detailed\nanalysis of the two essential diffusion constants, parallel and perpendicular\nto the director, in terms of Frank elastic constants, dielectric anisotropy,\nand applied magnetic field. We also point out the relevance of our results to\ndifferent liquid crystalline systems, such as discotic nematics, smectic-A\nphases, and polymer liquid crystals. Finally, we show that the dynamic\nabsorption coefficient is the angular average over the inverse viscosity, which\ngoverns the dynamics of director fluctuations.",
        "positive": "Effect of shape biaxiality on the phase behavior of colloidal\n  liquid-crystal monolayers: We extend our previous work on monolayers of uniaxial particles [J. Chem.\nPhys. 140, 204906 (2014)] to study the effect of particle biaxiality on the\nphase behavior of liquid-crystal monolayers. Particles are modelled as\nboard-like hard bodies with three different edge lengths\n$\\sigma_1\\geq\\sigma_2\\geq\\sigma_3$, and use is made of the\nrestricted-orientation approximation (Zwanzig model). A density-functional\nformalism based on the fundamental-measure theory is used to calculate phase\ndiagrams for a wide range of values of the largest aspect ratio\n($\\kappa_1=\\sigma_1/\\sigma_3\\in[1,100]$). We find that particle biaxiality in\ngeneral destabilizes the biaxial nematic phase already present in monolayers of\nuniaxial particles. While plate-like particles exhibit strong biaxial ordering,\nrod-like ones with $\\kappa_1>21.34$ exhibit reentrant uniaxial and biaxial\nphases. As particle geometry is changed from uniaxial- to increasingly\nbiaxial-rod-like, the region of biaxiality is reduced, eventually ending in a\ncritical-end point. For $\\kappa_1>60$, a density gap opens up in which the\nbiaxial nematic phase is stable for any particle biaxiality. Regions of the\nphase diagram where packing-fraction inversion occurs (i.e. packing fraction is\na decreasing function of density) are found. Our results are compared with the\nrecent experimental studies on nematic phases of magnetic nanorods."
    },
    {
        "anchor": "Inertial migration of neutrally buoyant particles in square channels at\n  high Reynolds numbers: KEY WORDS suspensions, inertial focusing, particle-laden flows, high Reynolds\nnumbers SHORT SUMMARY The inertial migration of particles in square channel\nflows at the micro-scale has been deeply investigated in the last two decades.\nThe well-known four equilibrium positions are located near the center of each\nchannel face at moderate Reynolds numbers [1]. More recently, Miura et al. [2]\nrevealed experimentally the presence of eight equilibrium positions in\nmillimetric square channels for Reynolds numbers higher than 250. The aim of\nthe present work is to extend these results obtained at millimeter scale to the\nmicrometer scale. To this end, in situ visualization of particles flowing in\nsquare micro-channels at Reynolds numbers ranging from 5 to 300 have been\nconducted and analyzed.",
        "positive": "Shear jamming, discontinuous shear thickening, and fragile states in dry\n  granular materials under oscillatory shear: We numerically study the linear response of two-dimensional frictional\ngranular materials under oscillatory shear. The storage modulus $G'$ and the\nloss modulus $G''$ in the zero strain rate limit depend on the initial strain\namplitude of the oscillatory shear before measurement. The shear jammed state\n(satisfying $G'>0$) can be observed at an amplitude greater than a critical\ninitial strain amplitude. The fragile state is defined by the emergence of\nliquid-like and solid-like states depending on the form of the initial shear.\nIn this state, the observed $G'$ after the reduction of the strain amplitude\ndepends on the phase of the external shear strain. The loss modulus $G''$\nexhibits a discontinuous jump corresponding to discontinuous shear thickening\nin the fragile state."
    },
    {
        "anchor": "Minimal energy packings and collapse of sticky tangent hard-sphere\n  polymers: We enumerate all minimal energy packings (MEPs) for small single linear and\nring polymers composed of spherical monomers with contact attractions and\nhard-core repulsions, and compare them to corresponding results for monomer\npackings. We define and identify ``dividing surfaces\" in polymer packings,\nwhich reduce the number of arrangements that satisfy hard-sphere and covalent\nbond constraints. Compared to monomer MEPs, polymer MEPs favor intermediate\nstructural symmetry over high and low symmetries. We also examine the\npacking-preparation dependence for longer single chains using molecular\ndynamics simulations. For slow temperature quenches, chains form crystallites\nwith close-packed cores. As quench rate increases, the core size decreases and\nthe exterior becomes more disordered. By examining the contact number, we\nconnect suppression of crystallization to the onset of isostaticity in\ndisordered packings. These studies represent a significant step forward in our\nability to predict how the structural and mechanical properties of compact\npolymers depend on collapse dynamics.",
        "positive": "Efficient sampling of knotting-unknotting pathways for semiflexible\n  Gaussian chains: We propose a stochastic method to generate exactly the overdamped Langevin\ndynamics of semi-flexible Gaussian chains, conditioned to evolve between given\ninitial and final conformations in a preassigned time. The initial and final\nconformations have no restrictions, and hence can be in any knotted state. Our\nmethod allows the generation of statistically independent paths in a\ncomputationally efficient manner. We show that these conditioned paths can be\nexactly generated by a set of local stochastic differential equations. The\nmethod is used to analyze the transition routes between various knots in\ncrossable filamentous structures, thus mimicking topological reconnections\noccurring in soft matter systems or those introduced in DNA by topoisomerase\nenzymes. We find that the average number of crossings, writhe and unknotting\nnumber are not necessarily monotonic in time and that more complex topologies\nthan the initial and final ones can be visited along the route."
    },
    {
        "anchor": "Binding of thermalized and active membrane curvature-inducing proteins: Membrane phase behavior induced by the binding of curvature-inducing proteins\nis studied by a combination of analytical and numerical approaches. In thermal\nequilibrium under the detailed balance between binding and unbinding, the\nmembrane exhibits three phases: an unbound uniform flat phase (U), a bound\nuniform flat phase (B), and a separated/corrugated phase (SC). In the SC phase,\nthe bound proteins form hexagonally-ordered bowl-shaped domains. The\ntransitions between the U and SC phases and between the B and SC phases are\nsecond order and first order, respectively. At a small spontaneous curvature of\nthe protein or high surface tension, the transition between B and SC phases\nbecomes continuous. Moreover, a first-order transition between the U and B\nphases is found at zero spontaneous curvature driven by the Casimir-like\ninteractions between rigid proteins. Furthermore, nonequilibrium dynamics is\ninvestigated by the addition of active binding and unbinding at a constant\nrate. The active binding and unbinding processes alter the stability of the SC\nphase.",
        "positive": "Asymmetric and Long Range Interactions in Shaken Granular Media: We use a computational model to investigate the emergence of interaction\nforces between pairs of intruders in a horizontally vibrated granular fluid.\nThe time evolution of a pair of particles shows a maximum of the likelihood to\nfind the pair at contact in the direction of shaking. This relative interaction\nis further studied by fixing the intruders in the simulation box where we\nidentify effective mechanical forces, and torques between particles and\nquantify an emergent long range attractive force as a function of the shaking\nrelative angle, amplitude, and the packing density of grains. We determine the\nlocal density and kinetic energy profiles of granular particles along the axis\nof the dimer to find no gradients in the density fields and additive gradients\nin the kinetic energies."
    },
    {
        "anchor": "Hysteresis, force oscillations and non-equilibrium effects in the\n  adhesion of spherical nanoparticles to atomically smooth surfaces: Molecular dynamics simulations are used to examine hysteretic effects and\ndistinctions between equilibrium and non-equilibrium aspects of particle\nadsorption on the walls of nano-sized fluidfilled channels. The force on the\nparticle and the system's Helmholtz free energy are found to depend on the\nparticle's history as well as on its radial position and the wetting properties\nof the fluid, even when the particle's motion occurs on time scales much longer\nthan the spontaneous adsorption time. The hysteresis is associated with changes\nin the fluid density in the gap between the particle and the wall, and these\nstructural rearrangements persist over surprisingly long times. The force and\nfree energy exhibit large oscillations with distance when the lattice of the\nstructured nanoparticle is held in register with that of the tube wall, but not\nif the particle is allowed to rotate freely. Adsorbed particles are trapped in\nfree energy minima in equilibrium, but if the particle is forced along the\nchannel the resulting stick-slip motion alters the fluid structure and allows\nthe particle to desorb.",
        "positive": "Dynamical fluctuations close to Jamming versus Vibrational Modes : a\n  pedagogical discussion illustrated on hard spheres simulations, colloidal and\n  granular experiments: Studying the jamming transition of granular and colloidal systems, has lead\nto a proliferation of theoretical and numerical results formulated in the\nlanguage of the eigenspectrum of the dynamical matrix for these disordered\nsystem. Only recently however, these modes have been accessed experimentally in\ncolloidal and granular media, computing the eigenmodes of the covariance matrix\nof the particle positions. At the same time new conceptual and methodological\nquestions have appeared, regarding the interpretation of these results. In the\npresent paper, we first give an overview of the theoretical framework which is\nappropriate to discuss the interpretation of the eigenmodes and eigenvalues of\nthe correlation matrix in terms of the vibrational properties of these systems.\n  We then illustrate several aspects of the statistical and data analysis\ntechniques which are necessary to extract reliable results from experimental\ndata. Concentrating on the case of hard sphere simulations, colloidal and\ngranular experiments, we discuss how to test the existence of a metastable\nstate, the statistical independence of the sampling, the effect of the\nexperimental resolution, and the harmonic hypothesis underlying the approach,\nhighlighting both its promises and limitations."
    },
    {
        "anchor": "Morphodynamics of Active Nematic Fluid Surfaces: Morphodynamic equations governing the behaviour of active nematic fluids on\ndeformable curved surfaces are constructed in the large deformation limit.\nEmphasis is placed on the formulation of objective rates that account for\nnormal deformations whilst ensuring that tangential flows are Eulerian, and the\nuse of the surface derivative (rather than the covariant derivative) in the\nnematic free energy, which elastically couples local order to out-of-plane\nbending of the surface. Focusing on surface geometry and its dynamical\ninterplay with the hydrodynamics, several illustrative instabilities are then\ncharacterised. These include cases where the role of the Scriven-Love number\nand its nematic analogue are non-negligible, and where the active nematic\nforcing can be characterised by an analogue of the F\\\"{o}ppl-von-K\\'{a}rm\\'{a}n\nnumber. For the former, flows and changes to the nematic texture are coupled to\nsurface geometry by viscous dissipation. This is shown to result in non-trivial\nrelaxation dynamics for a nematic tube. For the latter, the nematic active\nforcing couples to the surface bending terms of the nematic free energy,\nresulting in extensile (active ruffling) and contractile (active pearling)\ninstabilities in the tube shape, as well as active bend instabilities in the\nnematic texture. In comparison to the flat case, such bend instabilities now\nhave a threshold set by the extrinsic curvature of the tube. Finally, we\nexamine a topological defect located on an almost flat surface and show that\nthere exists a steady state where a combination of defect elasticity, activity\nand non-negligible spin-connection drive a shape change in the surface.",
        "positive": "Prevalence of approximate square root t relaxation for the dielectric\n  alpha process in viscous organic liquids: This paper presents dielectric relaxation data for organic glass-forming\nliquids compiled from different groups and supplemented by new measurements.\nThe main quantity of interest is the \"minimum slope\" of the $\\alpha$ dielectric\nloss plotted as a function of frequency in a log-log plot (i.e., the\nnumerically largest slope above the loss peak frequency). The data consisting\nof 347 spectra for 53 liquids show prevalence of minimum slopes close to -1/2,\ncorresponding to approximate square-root-time dependence of the dielectric\nrelaxation function at short times. The paper further studies possible\ncorrelations between minimum slopes and: 1) Temperature quantified via the\nloss-peak frequency; 2) How well an inverse power law fits data above the loss\npeak; 3) Degree of time-temperature superposition; 4) Loss-peak half width; 5)\nDeviation from non-Arrhenius behavior; 6) Loss strength. For the first three\npoints we find correlations that indicate a special status of liquids with\nminimum slopes close to -1/2. For the last three points only fairly\ninsignificant correlations are found with the exception of large-loss liquids,\nwhich have minimum slopes that are numerically significantly larger than 1/2\nand loss peak widths that are significantly smaller than those of most other\nliquids. We conclude that -- excluding large-loss liquids -- approximate $\\sqrt\nt$ relaxation appears to be a generic property of the $\\alpha$ relaxation of\norganic glass formers."
    },
    {
        "anchor": "Theory and simulations of toroidal and rod-like structures in\n  single-molecule DNA condensation: DNA condensation by multivalent cations plays a crucial role in genome\npackaging in viruses and sperm heads, and has been extensively studied using\nsingle-molecule experimental methods. In those experiments, the values of the\ncritical condensation forces have been used to estimate the amplitude of the\nattractive DNA-DNA interactions. Here, to describe these experiments, we\ndeveloped an analytical model and a rigid body Langevin dynamics assay to\ninvestigate the behavior of a polymer with self-interactions, in the presence\nof a traction force applied at its extremities. We model self-interactions\nusing a pairwise attractive potential, thereby treating the counterions\nimplicitly. The analytical model allows to accurately predict the equilibrium\nstructures of toroidal and rod-like condensed structures, and the dependence of\nthe critical condensation force on the DNA length. We find that the critical\ncondensation force depends strongly on the length of the DNA, and finite-size\neffects are important for molecules of length up to 10^5 {\\mu}m. Our Langevin\ndynamics simulations show that the force-extension behavior of the rod-like\nstructures is very different from the toroidal ones, so that their presence in\nexperiments should be easily detectable. In double-stranded DNA condensation\nexperiments, the signature of the presence of rod-like structures was not\nunambiguously detected, suggesting that the polyamines used to condense DNA may\nprotect it from bending sharply as needed in the rod-like structures",
        "positive": "Simulation of fluid flow in hydrophobic rough microchannels: Surface effects become important in microfluidic setups because the surface\nto volume ratio becomes large. In such setups the surface roughness is not any\nlonger small compared to the length scale of the system and the wetting\nproperties of the wall have an important influence on the flow. However, the\nknowledge about the interplay of surface roughness and hydrophobic\nfluid-surface interaction is still very limited because these properties cannot\nbe decoupled easily in experiments.\n  We investigate the problem by means of lattice Boltzmann (LB) simulations of\nrough microchannels with a tunable fluid-wall interaction. We introduce an\n``effective no-slip plane'' at an intermediate position between peaks and\nvalleys of the surface and observe how the position of the wall may change due\nto surface roughness and hydrophobic interactions.\n  We find that the position of the effective wall, in the case of a Gaussian\ndistributed roughness depends linearly on the width of the distribution.\nFurther we are able to show that roughness creates a non-linear effect on the\nslip length for hydrophobic boundaries."
    },
    {
        "anchor": "Wall entrapment of peritrichous bacteria: A mesoscale hydrodynamics\n  simulation study: Microswimmers such as E. Coli bacteria accumulate and exhibit an intriguing\ndynamics near walls, governed by hydrodynamic and steric interactions. Insight\ninto the underlying mechanisms and predominant interactions demand a detailed\ncharacterization of the entrapment process. We employ a mesoscale hydrodynamics\nsimulation approach to study entrapment of a E. coli-type cell at a no-slip\nwall. The cell is modeled by a spherocylindrical body with several explicit\nhelical flagella. Three stages of the entrapment process can be distinguished:\nthe approaching regime, where a cell swims toward the wall on a nearly straight\ntrajectory; a scattering regime, where the cell touches the wall, with an\nreorientation; and a surface-swimming regime. Our simulations show that steric\ninteractions may dominate the entrapment process, yet, hydrodynamic\ninteractions slow down the adsorption dynamics close to the boundary and imply\na circular motion on the wall. The locomotion of the cell is characterized by a\nstrong wobbling dynamics, with cells preferentially pointing toward the wall.",
        "positive": "Dynamics of polymer translocation into an anisotropic confinement: Using Langevin dynamics simulations, we investigate the dynamics of a\nflexible polymer translocation into a confined area under a driving force\nthrough a nanopore. We choose an ellipsoidal shape for the confinement and\nconsider the dependence of the asymmetry of the ellipsoid measured by the\naspect ratio on the translocation time. Compared with an isotropic confinement\n(sphere), an anisotropic confinement (ellipsoid) with the same volume slows\ndown the translocation, and the translocation time increases with increasing\nthe aspect ratio of the ellipsoid. We further find that it takes different time\nfor polymer translocation into the same ellipsoid through major-axis and\nminor-axis directions, depending on the average density of the whole chain in\nthe ellipsoid, $\\phi$. For $\\phi$ lower than a critical value $\\phi_c$, the\ntranslocation through minor axis is faster, and vice versa. These complicated\nbehaviors are interpreted by the degree of the confinement and anisotropic\nconfinement induced folding of the translocated chain."
    },
    {
        "anchor": "Critical Field Strength in an Electroclinic Liquid Crystal Elastomer: We elucidate the polymer dynamics of a liquid crystal elastomer based on the\ntime-dependent response of the pendent liquid crystal mesogens. The molecular\ntilt and switching time of mesogens are analyzed as a function of temperature\nand cross-linking density upon application of an electric field. We observe an\nunexpected maximum in the switching time of the liquid crystal mesogens at\nintermediate field strength. Analysis of the molecular tilt over multiple time\nregimes correlates the maximum response time with a transition to entangled\npolymer dynamics at a critical field strength.",
        "positive": "Power functional theory for many-body dynamics: The rich and diverse dynamics of particle-based systems ultimately originates\nfrom the coupling of their degrees of freedom via internal interactions. To\narrive at a tractable approximation of such many-body problems, coarse-graining\nis often an essential step. Power functional theory provides a unique and\nmicroscopically sharp formulation of this concept. The approach is based on an\nexact one-body variational principle to describe the dynamics of both\noverdamped and inertial classical and quantum many-body systems. In\nequilibrium, density functional theory is recovered, and hence spatially\ninhomogeneous systems are described correctly. The dynamical theory operates on\nthe level of time-dependent one-body correlation functions. Two- and\nhigher-body correlation functions are accessible via the dynamical test\nparticle limit and the nonequilibrium Ornstein-Zernike route. We describe the\nstructure of this functional approach to many-body dynamics, including much\nbackground as well as applications to a broad range of dynamical situations,\nsuch as the van Hove function in liquids, flow in nonequilibrium steady states,\nmotility-induced phase separation of active Brownian particles, lane formation\nin binary colloidal mixtures, and both steady and transient shear phenomena."
    },
    {
        "anchor": "Correlating microscopic viscoelasticity and structure of an aging\n  colloidal gel using active microrheology and cryogenic scanning electron\n  microscopy: Optical tweezers (OTs) can detect pico-Newton range forces operating on a\ncolloidal particle trapped in a medium and have been successfully utilized to\ninvestigate complex systems with internal structures. Laponite clay particles\nin an aqueous medium self-assemble to form microscopic networks over time as\nelectrostatic interactions between the particles gradually evolve in a physical\naging process. We investigate the forced movements of an optically trapped\nmicron-sized colloidal probe particle, suspended in an aging Laponite\nsuspension, as the underlying Laponite microstructures gradually develop. Our\nOT-based oscillatory active microrheology experiments allow us to investigate\nthe mechanical responses of the evolving microstructures in aging aqueous clay\nsuspensions of concentrations ranging from 2.5% w/v to 3.0% w/v and at several\naging times between 90 and 150 minutes. We repeat such oscillatory measurements\nfor a range of colloidal probe particle diameters and investigate the effect of\nprobe size on the microrheology of the aging suspensions. Using cryogenic field\nemission scanning electron microscopy (cryo-FESEM), we examine the average pore\nareas of the Laponite suspension microstructures for various sample\nconcentrations and aging times. By combining our OT and cryo-FESEM data, we\nreport here for the first time to the best of our knowledge, an inverse\ncorrelation between the crossover modulus and the average pore diameter of the\naging suspension microstructures for the different suspension concentrations\nand probe particle sizes studied here.",
        "positive": "Topological characterization of the continuum of allosteric response: Allosteric regulation in proteins is often accompanied by conformational\nchanges that facilitate transmission of mechanical signals between distant\nligand binding sites. Typically, these deformations are classified in terms of\nspecific archetypes, including various types of hinge mechanisms or allosteric\npathways localized to sequences of amino acids.However, many allosteric\ndeformations resist such strict categorization. Here, we introduce a\nquantitative topological description of allosteric deformation, unifying all\narchetypal mechanisms into a single framework. The topological description\naligns with two key structural features often associated with allosteric\ndeformations, namely hinge domains and allosteric pathways, enabling us to\nquantify the significance of each of these features. To develop the analysis,\nwe tune computer-generated mechanical networks to perform allostery-like\nfunctions, obtaining an ensemble of networks that establish a range of possible\nallosteric deformations. The analysis shows that these networks' allosteric\nmechanisms cannot be described in terms of discrete archetypes - they fall on a\ncontinuum. We then apply the same analysis to a collection of allosteric\nproteins with similar results, showing that our framework encompasses these\nproteins as well as designed allosteric networks. Our results provide a new\npicture for allostery, demonstrating not only how it can be described\nquantitatively, but also giving insight into how it emerges as a collective\nproperty."
    },
    {
        "anchor": "Lattice Boltzmann Methods and Active Fluids: We review the state of the art of active fluids with particular attention to\nhydrodynamic continuous models and to the use of Lattice Boltzmann Methods\n(LBM) in this field. We present the thermodynamics of active fluids, in terms\nof liquid crystals modelling adapted to describe large-scale organization of\nactive systems, as well as other effective phenomenological models. We discuss\nhow LBM can be implemented to solve the hydrodynamics of active matter,\nstarting from the case of a simple fluid, for which we explicitly recover the\ncontinuous equations by means of Chapman-Enskog expansion. Going beyond this\nsimple case, we summarize how LBM can be used to treat complex and active\nfluids. We then review recent developments concerning some relevant topics in\nactive matter that have been studied by means of LBM: spontaneous flow,\nself-propelled droplets, active emulsions, rheology, active turbulence, and\nactive colloids.",
        "positive": "Twist of cholesteric liquid crystal cells: stability of helical\n  structures and anchoring energy effects: We consider helical configurations of a cholesteric liquid crystal (CLC)\nsandwiched between two substrates with homogeneous director orientation favored\nat both confining plates. We study the CLC twist wavenumber $q$ characterizing\nthe helical structures in relation to the free twisting number $q_0$ which\ndetermines the equilibrium value of CLC pitch, $P_0=2\\pi/q_0$. We investigate\nthe instability mechanism underlying transitions between helical structures\nwith different spiral half-turn numbers. Stability analysis shows that for\nequal finite anchoring strengths this mechanism can be dominated by in-plane\ndirector fluctuations. In this case the metastable helical configurations are\nseparated by the energy barriers and the transitions can be described as the\ndirector slippage through these barriers. We extend our analysis to the case of\nan asymmetric CLC cell in which the anchoring strengths at the two substrates\nare different. The asymmetry introduces two qualitatively novel effects: (a)\nthe intervals of twist wavenumbers representing locally stable configurations\nwith adjacent helix half-turn numbers are now separated by the instability\ngaps; and (b) sufficiently large asymmetry, when the difference between\nazimuthal anchoring extrapolation lengths exceeds the thickness of the cell,\nwill suppress the jump-like behaviour of the twist wavenumber."
    },
    {
        "anchor": "Thermodynamics, Dynamics, and Kinetics of Nanostructured Fluid-Solid\n  Interfaces: This article covers thermodynamic, dynamic, and kinetic models that are\nsuitable for the analysis of wetting, adsorption, and related interfacial\nphenomena in colloidal and multiphase systems. Particular emphasis is made on\ndescribing crucial physical assumptions and the validity range of the described\ntheoretical approaches and predictive models. The classical sharp interface\ntreatment of thermodynamic systems where a perfectly smooth surface is assumed\nto separate homogeneous phases can present significant limitations when\nanalyzing systems that are subject to thermal motion and present multiple\nmetastable states caused by interfacial heterogeneities of nanoscale\ndimensions. Mesoscopic approaches such as stochastic Langevin dynamics can\nextend the application of sharp interface models to a wide variety of systems\nexhibiting metastability as they undergo thermal motion. For such metastable\nsystems, dynamic and kinetic equations can describe the evolution of observable\n(macroscopic) variables as the system approaches thermodynamic equilibrium.\nSufficiently close to equilibrium, Kramers theory of thermally activated escape\nfrom metastable states can be effectively employed to describe diverse wetting\nand interfacial processes via kinetic equations. Future directions for further\nadvancement and application of thermodynamic, dynamic, and kinetic models are\nbriefly discussed in the context of current technological developments\ninvolving nanoparticles, nanofluidics, and nanostructured surfaces.",
        "positive": "Phyllotactic description of hard sphere packing in cylindrical channels: We develop a simple analytical theory that relates dense sphere packings in a\ncylinder to corresponding disk packings on its surface. It applies for ratios\nR=D/d (where d and D are the diameters of the hard spheres and the bounding\ncylinder, respectively) up to R=1+1/sin(pi/5). Within this range the densest\npackings are such that all spheres are in contact with the cylindrical\nboundary. The detailed results elucidate extensive numerical simulations by\nourselves and others by identifying the nature of all competing phases."
    },
    {
        "anchor": "Nonlinear Indentation of Second-order Hyperelastic Materials: The classical problem of indentation on an elastic substrate has found new\napplications in the field of the Atomic Force Microscopy. However, linearly\nelastic indentation models are not sufficiently accurate to predict the\nforce-displacement relationship at large indentation depths. For hyperelastic\nmaterials, such as soft polymers and biomaterials, a nonlinear indentation\nmodel is needed. In this paper, we use second-order elasticity theory to\ncapture larger amplitude deformations and material nonlinearity. We provide a\ngeneral solution for the contact problem for deformations that are second-order\nin indentation amplitude with arbitrary indenter profiles. Moreover, we derive\nanalytical solutions by using either parabolic or quartic surfaces to mimic a\nspherical indenter. The analytical prediction for a quartic surface agrees well\nwith finite element simulations using a spherical indenter for indentation\ndepths on the order of the indenter radius. In particular, the relative error\nbetween the two approaches is less than 1% for an indentation depth equal to\nthe indenter radius, an order of magnitude less than that observed with models\nwhich are either first-order in indentation amplitude or those which are\nsecond-order in indentation amplitude but with a parabolic indenter profile.",
        "positive": "How short-range attractions impact the structural order,\n  self-diffusivity, and viscosity of a fluid: We present molecular simulation data for viscosity, self-diffusivity, and the\nlocal structural ordering of (i) a hard-sphere fluid and (ii) a square-well\nfluid with short-range attractions. The latter fluid exhibits a region of\ndynamic anomalies in its phase diagram, where its mobility increases upon\nisochoric cooling, which is found to be a subset of a larger region of\nstructural anomalies, in which its pair correlations strengthen upon isochoric\nheating. This \"cascade of anomalies\" qualitatively resembles that found in\nrecent simulations of liquid water. The results for the hard-sphere and\nsquare-well systems also show that the breakdown of the Stokes-Einstein\nrelation upon supercooling occurs for conditions where viscosity and\nself-diffusivity develop different couplings to the degree of pairwise\nstructural ordering of the liquid. We discuss how these couplings reflect\ndynamic heterogeneities. Finally, we note that the simulation data suggests how\nrepulsive and attractive glasses may generally be characterized by two distinct\nlevels of short-range structural order."
    },
    {
        "anchor": "Molecular mobility in driven monomeric and polymeric glasses: We show that in monomeric supercooled liquids and glasses that are\nplastically flowing at a constant shear stress $\\sigma$ while being deformed\nwith strain rate $\\dot{\\epsilon}$, the microscopic structural relaxation time\n$\\tau_{\\rm str}$ is given by the universal relation\n$\\sigma/G_\\infty\\dot{\\epsilon}$ with $G_\\infty$ a modulus. This equality holds\nfor all rheological regimes from temperatures above the glass transition all\nthe way to the athermal limit, and arises from the competing effects of elastic\nloading and viscous dissipation. In macromolecular (polymeric) glasses,\nhowever, the stress decouples from this relaxation time and $\\tau_{\\rm str}$ is\nin fact further reduced even though $\\sigma$ rises during glassy strain\nhardening. We develop expressions to capture both effects and thus provide a\nframework for analyzing mobility measurements in glassy materials.",
        "positive": "Dynamics and friction of a large colloidal particle in a bath of hard\n  spheres: Langevin dynamics simulations and hydrodynamic description: The analysis of the dynamics of tracer particles in a complex bath can\nprovide valuable information about the microscopic behaviour of the bath. In\nthis work, we study the dynamics of a forced tracer in a colloidal bath by\nmeans of Langevin dynamics simulations and a theory model within continuum\nmechanics. In the simulations, the bath is comprised by quasi-hard spheres with\na volume fraction of 50% immersed in a featureless quiescent solvent, and the\ntracer is pulled with a constant small force (within the linear regime). The\ntheoretical analysis is based on the Navier Stokes equation, where a term\nproportional to the velocity arises from coarse-graining the friction of the\ncolloidal particles with the solvent. As a result, the final equation is\nsimilar to the Brinkman model, although the interpretation is different. A\nlength scale appears in the model, 1/k_0, where the transverse momentum\ntransport crosses over to friction with the solvent. The effective friction\ncoefficient experienced by the tracer grows with the tracer size faster than\nthe prediction from Stokes law. Additionally, the velocity profiles in the bath\ndecay faster than in a Newtonian fluid. The comparison between simulations and\ntheory points to a boundary condition of effective partial slip at the tracer\nsurface. We also study the fluctuations in the tracer position, showing that it\nreaches diffusion at long times, with a subdiffusive regime at intermediate\ntimes. The diffusion coefficient, obtained from the long-time slope of the mean\nsquared displacement, fulfills the Stokes-Einstein relation with the friction\ncoefficient calculated from the steady tracer velocity, confirming the validity\nof the linear response formalism."
    },
    {
        "anchor": "A lattice gas model of avalanches in a granular pile: A granular media lattice gas (GMLG) model is used to study avalanches in a\ntwo-dimensional granular pile. We demonstrate the efficiency of the algorithm\nby showing that several features of the non-critical behaviour of real sandpile\nsurfaces, such as the bounded outflow statistics or the finite-size effect of\nthe time evolution of the pile mass, can be reproduced by this simulation\napproach.",
        "positive": "Force dependent fragility in RNA hairpins: We apply Kramers theory to investigate the dissociation of multiple bonds\nunder mechanical force and interpret experimental results for the\nunfolding/refolding force distributions of an RNA hairpin pulled at different\nloading rates using laser tweezers. We identify two different kinetic regimes\ndepending on the range of forces explored during the unfolding and refolding\nprocess. The present approach extends the range of validity of the two-states\napproximation by providing a theoretical framework to reconstruct free-energy\nlandscapes and identify force-induced structural changes in molecular\ntransition states using single molecule pulling experiments. The method should\nbe applicable to RNA hairpins with multiple kinetic barriers."
    },
    {
        "anchor": "Distortional Lifshitz Vectors and Helicity in Nematic Free Energy\n  Density: Here we discuss the free energy of nematic liquid crystals using two vectors\nand the helicity, with the aim of having a compact form of its density. The two\nvectors are due to the splay and bend distortions of the director field. They\nhave a polar nature, whereas the helicity is a pseudoscalar.",
        "positive": "A new mechanism for granular segregation: A novel process is described that produces horizontal size segregation in a\nvertically vibrated layer of granular material. The behavior is a consequence\nof two distinct phenomena that are unique to excited granular media: vibration\nwhich causes the larger particles to rise to the top of the layer, and a\nvibrating base with a sawtooth surface profile which can produce stratified\nflows in opposite directions at different heights within the layer. The result\nof combining these effects is that large and small particles are horizontally\ndriven in opposite directions. The observations reported here are based on\ncomputer simulations of granular models in two and three dimensions."
    },
    {
        "anchor": "Partial rejuvenation of a colloidal glass: We study the effect of shear on the aging dynamics of a colloidal suspension\nof synthetic clay particles. We find that a shear of amplitude $\\gamma$ reduces\nthe relaxation time measured just after the cessation of shear by a factor\n$\\exp(-\\gamma/\\gamma_c)$, with $\\gamma_c \\sim 5%$, and is independent of the\nduration and the frequency of the shear. This simple law for the rejuvenation\neffect shows that the energy involved in colloidal rearrangements is\nproportional to the shear amplitude, $\\gamma$, rather than $\\gamma^2$, leading\nto an Eyring-like description of the dynamics of our system.",
        "positive": "Diffusion of Point Defects in Two-Dimensional Colloidal Crystals: We report the first study of the dynamics of point defects, mono and\ndi-vacancies, in a confined 2-D colloidal crystal in real space and time using\ndigital video microscopy. The defects are introduced by manipulating individual\nparticles with optical tweezers. The diffusion rates are measured to be\n$D_{mono}/a^{2}\\cong3.27\\pm0.03$Hz for mono-vacancies and\n$D_{di}/a^{2}\\cong3.71\\pm0.03$Hz for di-vacancies. The elementary diffusion\nprocesses are identified and it is found that the diffusion of di-vacancies is\nenhanced by a \\textit{dislocation dissociation-recombination} mechanism.\nFurthermore, the defects do not follow a simple random walk but their hopping\nexhibits memory effects, due to the reduced symmetry (compared to the\ntriangular lattice) of their stable configurations, and the slow relaxation\nrates of the lattice modes."
    },
    {
        "anchor": "The new very small angle neutron scattering spectrometer at Laboratoire\n  Leon Brillouin: The design and characteristics of the new very small angle neutron scattering\nspectrometer under construction at the Laboratoire Leon Brillouin is described.\nIts goal is to extend the range of scattering vectors magnitudes towards\n2x10{-4} /A. The unique feature of this new spectrometer is a high resolution\ntwo dimensional image plate detector sensitive to neutrons. The wavelength\nselection is achieved by a double reflection supermirror monochromator and the\ncollimator uses a novel multibeam design.",
        "positive": "Spectrins in Axonal Cytoskeletons: Dynamics Revealed by Extensions and\n  Fluctuations: The macroscopic properties, the properties of individual components and how\nthose components interact with each other are three important aspects of a\ncomposited structure. An understanding of the interplay between them is\nessential in the study of complex systems. Using axonal cytoskeleton as an\nexample system, here we perform a theoretical study of slender structures that\ncan be coarse-grained as a simple smooth 3-dimensional curve. We first present\na generic model for such systems based on the fundamental theorem of curves. We\nuse this generic model to demonstrate the applicability of the well-known\nworm-like chain (WLC) model to the network level and investigate the situation\nwhen the system is stretched by strong forces (weakly bending limit). We\nspecifically studied recent experimental observations that revealed the\nhitherto unknown periodic cytoskeleton structure of axons and measured the\nlongitudinal fluctuations. Instead of focusing on single molecules, we apply\nanalytical results from the WLC model to both single molecule and network\nlevels and focus on the relations between extensions and fluctuations. We show\nhow this approach introduces constraints to possible local dynamics of the\nspectrin tetramers in the axonal cytoskeleton and finally suggests simple but\nself-consistent dynamics of spectrins in which the spectrins in one spatial\nperiod of axons fluctuate in-sync."
    },
    {
        "anchor": "Diffusive growth of polydisperse hard-sphere crystals: Unlike atoms, colloidal particles are not identical, but can only be\nsynthesised within a finite size tolerance. Colloids are therefore\npolydisperse, i.e. mixtures of infinitely many components with sizes drawn from\na continuous distribution. We model the crystallisation of hard-sphere colloids\n(with/without attractions) from an initially amorphous phase. Though the\npolydisperse hard-sphere phase diagram has been widely studied, it is not\nstraightforwardly applicable to real colloidal crystals, since they are\ninevitably out of equilibrium. The process by which colloidal crystals form\ndetermines the size distribution of the particles that comprise them. Once\nfrozen into the crystal lattice, the particles are caged so that the\ncomposition cannot subsequently relax to the equilibrium optimum. We predict\nthat the mean size of colloidal particles incorporated into a crystal is\nsmaller than anticipated by equilibrium calculations. This is because small\nparticles diffuse fastest and therefore arrive at the crystal in\ndisproportionate abundance.",
        "positive": "Nematronics: Reciprocal coupling between ionic currents and nematic\n  dynamics: Adopting a spintronics-inspired approach, we study the reciprocal coupling\nbetween ionic charge currents and nematic texture dynamics in a uniaxial\nnematic electrolyte. Assuming quenched fluid dynamics, we develop equations of\nmotion analogously to spin torque and spin pumping. Based on the principle of\nleast dissipation of energy, we derive the adiabatic \"nematic torque\" exerted\nby ionic currents on the nematic director field as well as the reciprocal\nmotive force on ions due to the orientational dynamics of the director. We\ndiscuss several simple examples that illustrate the potential functionality of\nthis coupling. Furthermore, using our phenomenological framework, we propose a\npractical means to extract the coupling strength through impedance measurements\non a nematic cell. Exploring further applications based on this physics could\nfoster the development of nematronics -- nematic iontronics."
    },
    {
        "anchor": "Layering, freezing and re-entrant melting of hard spheres in soft\n  confinement: Confinement can have a dramatic effect on the behavior of all sorts of\nparticulate systems and it therefore is an important phenomenon in many\ndifferent areas of physics and technology. Here, we investigate the role played\nby the softness of the confining potential. Using grand canonical Monte Carlo\nsimulations, we determine the phase diagram of three-dimensional hard spheres\nthat in one dimension are constrained to a plane by a harmonic potential. The\nphase behavior depends strongly on the density and on the stiffness of the\nharmonic confinement. Whilst we find the familiar sequence of confined\nhexagonal and square-symmetric packings, we do not observe any of the usual\nintervening ordered phases. Instead, the system phase separates under strong\nconfinement, or forms a layered re-entrant liquid phase under weaker\nconfinement. It is plausible that this behavior is due to the larger positional\nfreedom in a soft confining potential and to the contribution that the\nconfinement energy makes to the total free energy. The fact that specific\nstructures can be induced or suppressed by simply changing the confinement\nconditions (e.g. in a dielectrophoretic trap) is important for applications\nthat involve self-assembled structures of colloidal particles.",
        "positive": "A sequential algorithm with a built in tension-propagation mechanism for\n  modeling the chain-like bodies dynamics: In the paper a novel stochastic algorithm designed to study of chain-like\nbodies dynamics is introduced. This algorithm models chain movements induced by\nthe tension propagation and its main idea relies on the sequentialization of\neach movement into a sequence of virtual steps made by chain's segments. In\nthis spirit, any accepted chain's new position is achieved by a move that is\ninitiated by a shift of one segment picked randomly according to a\nproblem-specific probability distribution and then followed by a cascade of\nsome other segments' position rearrangements. The rearrangement process\nterminates when the tension in the chain induced by the initial shift is\nreleased. A considerable gain in the volume of allocated memory is achieved\nbecause the virtual steps lead to new conformations that are very likely to be\nacceptable by nature. We validate the algorithm by comparing passage times for\npolymer translocation through a pore obtained within this algorithm with their\ncounterparts reported in the literature. In this paper we focus on a\nfluctuating-bond model of self-avoiding polymers on 2D square lattice. Based on\nthe large data sets received in our simulations we have found that the\ntransolaction time is distributed according to the Moyal probability\ndistribution. This novel finding enables us to identify the theoretical form of\nvarious distributions of translocation time reported in literature by\nexpressing them very accurately with the help of this two-parameter family of\nprobability distributions"
    },
    {
        "anchor": "Correspondence Between the Phase Diagrams of TIP5P Water and a\n  Spherically Symmetric Repulsive Ramp Potential: We perform molecular dynamics simulations of a well-known water model (the\nTIP5P pair potential) and a simple liquid model (a two-scale repulsive ramp\npotential) to compare the regions of anomalous behavior in their phase\ndiagrams. We select the parameters of the ramp potential by mapping it to an\neffective pair potential derived from the TIP5P model. We find that the regions\nof anomalous behavior in the phase diagrams of both systems can be mapped onto\neach other if (i) pressure $P$ and temperature $T$ are replaced by $T-T_{C}$\nand $P-P_{C}$, respectively, where $(T_{C},P_{C})$ are the coordinates of the\nliquid-liquid critical point of the corresponding system; and (ii) a single\nramp particle corresponds to two TIP5P molecules. We present heuristic\narguments supporting point (ii). We also argue that the water-like anomalies in\nthe ramp potential are due to the ability of the particles to reproduce, upon\ncompression or heating, the migration of water molecules from the second shell\nto its first shell.",
        "positive": "Percolation transition in the packing of bidispersed particles on curved\n  surfaces: We study packings of bidispersed spherical particles on a spherical surface.\nThe presence of curvature necessitates defects even for monodispersed\nparticles; bidispersity either leads to a more disordered packing for nearly\nequal radii, or a higher fill fraction when the smaller particles are\naccomodated in the interstices of the larger spheres. Variation in the packing\nfraction is explained by a percolation transition, as chains of defects or\nscars previously discovered in the monodispersed case grow and eventually\ndisconnect the neighbor graph."
    },
    {
        "anchor": "An algebraic thixotropic elasto-viscoplastic constitutive equation\n  describing pre-yielding solid and post-yielding liquid behaviours: Formulating an appropriate elasto-viscoplastic constitutive equation is\nchallenging, especially for a model describing pre-yielding solid and\npost-yielding liquid behaviours. Oldroyds 1946 formulation was one of the first\nmodels explaining it, however, assumptions of a simple linear elastic and\nquasi-static deformation before yielding made his model idealistic. At the same\ntime, the quasi-static pre-yielding deformation assumption open-up the\npossibility for pre-yielding viscous and plastic deformation in the absence of\nquasi-static conditions. Most early models followed Oldroyds pre-yielding\nlinear elastic assumption. Here, we discuss the structural parameters based\nthixotropic non-linear elasto-viscoplastic constitutive model valid for\nreversible and irreversible thixotropic materials. In this work, we have\nconsidered non-linear elastic and plastic behaviours before yielding. Despite\nbeing a simple algebraic equation, our model explains both the viscosity\nplateau at low shear rates and the diverging zero shear rate viscosity, using\nthe same parameters but different shear histories. Our model also predicts\nexperimentally observable transient and steady-state shear banding.\nFurthermore, our model effectively predicts waiting-time-dependent stress\novershoot during startup flow, stress hysteresis in shear ramps, sudden\nstepdown shear rate test results, and viscosity bifurcation phenomena. At the\nsteady state, it reduces to either Bingham, Herschel Bulkley type, or Newtonian\nfluids model, depending on shear histories. Our model requires only four and\nfive for the irreversible and reversible model, respectively, compared to six\nor seven parameters required by the existing model. With fewer parameters, our\nmodel favourably predicts recent experimental results. The current framework\nhas the potential to provide a possible physical interpretation of the Bingham\nmodel.",
        "positive": "Brownian noise effects on magnetic focusing of prolate and oblate\n  spheroids in channel flow: We investigate Brownian noise effects on magnetic focusing of prolate and\noblate spheroids carrying permanent magnetic dipoles in channel (Poiseuille)\nflow subject to a uniform magnetic field. The focusing is effected by the\nlow-Reynolds-number wall-induced hydrodynamic lift which can be tuned via tilt\nangle of the field relative to the flow direction. This mechanism is\nincorporated in a steady-state Smoluchowski equation that we solve numerically\nto analyze the noise effects through the joint position-orientation probability\ndistribution function of spheroids within the channel. The results feature\npartial and complete pinning of spheroidal orientation as the field strength is\nincreased and reveal remarkable and even counterintuitive noise-induced\nphenomena (specifically due to translational particle diffusivity) deep into\nthe strong-field regime. These include field-induced defocusing, or lateral\nbroadening of the focused spheroidal layer, upon strengthening the field. We\nmap out focusing `phase' diagrams based on the field strength and tilt angle to\nillustrate different regimes of behavior including centered focusing and\ndefocusing in transverse field, and off-centered focusing in tilted fields. The\nlatter encompasses two subregimes of optimal and shouldered focusing where\nspheroidal density profiles across the channel width display either an isolated\noff-centered peak or a skewed peak with a pronounced shoulder stretching toward\nthe channel center. We corroborate our results by analyzing stability of\ndeterministic fixed points and a reduced one-dimensional probabilistic theory\nwhich we introduce to semiquantitatively explain noise-induced behavior of\npinned spheroids under strong fields. We also elucidate the implications of our\nresults for efficient shape-based sorting of magnetic spheroids."
    },
    {
        "anchor": "Liquid crystals of hard rectangles on flat and cylindrical manifolds: Using the classical density functional theory of freezing and Monte Carlo\ncomputer simulations, we explore the liquid-crystalline phase behavior of hard\nrectangles on flat and cylindrical manifolds. Moreover, we study the effect of\na static external field which couples to the rectangles' orientations, aligning\nthem towards a preferred direction. In the flat and field-free case, the bulk\nphase diagram involves stable isotropic, nematic, tetratic, and smectic phases\ndepending on the aspect ratio and number density of the particles. The external\nfield shifts the transition lines significantly and generates a binematic phase\nat the expense of the tetratic phase. On a cylindrical manifold, we observe\ntilted smectic-like order, as obtained by wrapping a smectic layer around a\ncylinder. We find in general good agreement between our density functional\ncalculations and particle-resolved computer simulations and mention possible\nsetups to verify our predictions in experiments.",
        "positive": "A New Interpretation of Three-Dimensional Particle Geometry: M-A-V-L: This study provides a new interpretation of 3D particle geometry that\nunravels the 'interrelation' of the four geometry parameters, i.e., morphology\nM, surface area A, volume V, and size L, for which a new formula, M =\nA/V$\\times$L/6, is introduced to translate the 3D particle morphology as a\nfunction of surface area, volume, and size. The A/V$\\times$L of a sphere is\ninvariably 6, which is placed in the denominator of the formula, and therefore\nM indicates a relative morphological irregularity compared to the sphere. The\nminimum possible value of M is clearly one, and M may range approximately to\nthree for coarse-grained mineral particles. Furthermore, the proposed formula,\nM = A/V$\\times$L/6, enables to graphically preserve the four parameters'\nrelations when plotting the geometry parameter distributions. This study\ndemonstrates the approach with two plot spaces that represent (i) L vs. M and\n(ii) A/V vs. V, where A/V works as the messenger between these two spaces as\nA/V = M/L$\\times$6. Therefore, this approach helps comprehensively address the\nfour-dimensional aspects of the 3D particle geometry and better understand the\nparameters' combined influence on the mechanical behavior of granular\nmaterials.\n  Keywords: 3D particle geometry; Morphology; Surface area; Volume; Size;"
    },
    {
        "anchor": "Buckling of swelling gels: The patterns arising from the differential swelling of gels are investigated\nexperimentally and theoretically as a model for the differential growth of\nliving tissues. Two geometries are considered: a thin strip of soft gel clamped\nto a stiff gel, and a thin corona of soft gel clamped to a disk of stiff gel.\nWhen the structure is immersed in water, the soft gel swells and bends out of\nplane leading to a wavy periodic pattern which wavelength is measured. The\nlinear stability of the flat state is studied in the framework of linear\nelasticity using the equations for thin plates. The flat state is shown to\nbecome unstable to oscillations above a critical swelling rate and the computed\nwavelengths are in quantitative agreement with the experiment.",
        "positive": "Gyromagnetic effects in dynamics of magnetic microparticles: We derive equations of motion for paramagnetic and ferromagnetic particles\nfully accounting for gyromagnetic effects. Considering the Einstein-de Haas\neffect for an ellipsoidal paramagnetic particle we find that starting from a\nquiescent non-magnetized state, after the field is switched on a rotation along\nthe short axis is established. This is confirmed by the stability analysis of\nthe fixed points of the corresponding ordinary differential equations. In the\ncase of a ferromagnetic particle we integrate the equations of motion in the\ndissipationless case by finding the integrals of motion. We also reformulate\nthe equations in a Hamiltonian framework in this case and find a period of\nsmall nutation oscillations."
    },
    {
        "anchor": "Non-monotonic response of a sheared magnetic liquid crystal to an\n  external field: Utilizing molecular dynamics simulations, we report a non-monotonic\ndependence of the shear stress on the strength of an external magnetic field\n($H$) in a liquid-crystalline mixture of magnetic and non-magnetic anisotropic\nparticles. This non-monotonic behavior is in sharp contrast with the\nwell-studied monotonic $H$-dependency of the shear stress in conventional\nferrofluids, where the shear stress increases with $H$ until it reaches a\nsaturation value. We relate the origin of this non-monotonicity to the\ncompeting effects of particle alignment along the shear-induced direction, on\nthe one hand, and the magnetic field direction, on the other hand. To isolate\nthe role of these competing effects, we consider a two-component mixture\ncomposed of particles with effectively identical steric interactions, where the\norientations of a small fraction, i.e.\\ the magnetic ones, are coupled to the\nexternal magnetic field. By increasing $H$ from zero, the orientations of the\nmagnetic particles show a Fr\\'{e}ederickz-like transition and eventually start\ndeviating from the shear-induced orientation, leading to an increase in shear\nstress. Upon further increase of $H$, a demixing of the magnetic particles from\nthe non-magnetic ones occurs which leads to a drop in shear stress, hence\ncreating a non-monotonic response to $H$. Unlike the equilibrium demixing\nphenomena reported in previous studies, the demixing observed here is neither\ndue to size-polydispersity nor due to a wall-induced nematic transition. Based\non a simplified Onsager analysis, we rather argue that it occurs solely due to\npacking entropy of particles with different shear- or magnetic-field-induced\norientations.",
        "positive": "Non-destructive mapping of stress, strain and stiffness of thin\n  elastically deformed materials: Knowing the stress within a soft material is of fundamental interest to basic\nresearch and practical applications, such as soft matter devices, biomaterial\nengineering, and medical sciences. However, it is challenging to measure stress\nfields in situ in a non-invasive way. It becomes even more difficult if the\nmechanical properties of the material are unknown or altered by the stress.\nHere we present a robust non-destructive technique capable of measuring in situ\nstress and strain in elastically deformed thin films without the need to know\ntheir material properties. The technique is based on measuring elastic wave\nspeeds, and then using a universal dispersion curve we derived for Lamb wave to\npredict the local stress and strain. Using optical coherence tomography, we\nexperimentally verified the method for a rubber sheet, a cling film, and the\nleather skin of a musical instrument."
    },
    {
        "anchor": "Single-parameter aging in a binary Lennard-Jones system: This paper studies physical aging by computer simulations of a 2:1\nKob-Andersen binary Lennard-Jones mixture, a system that is less prone to\ncrystallization than the standard 4:1 composition. Starting from\nthermal-equilibrium states, the time evolution of the following four quantities\nis monitored following up and down jumps in temperature: the potential energy,\nthe virial, the average squared force, and the Laplacian of the potential\nenergy. Despite the fact that significantly larger temperature jumps are\nstudied here than in previous experiments, to a good approximation all four\nquantities conform to the single-parameter-aging scenario derived and validated\nfor small jumps in experiments [Hecksher et al., J. Chem. Phys. 142, 241103\n(2015)]. As a further confirmation of single-parameter aging with a common\nmaterial time for the different quantities monitored, their relaxing parts are\nfound to be almost identical for all temperature jumps.",
        "positive": "Single file dynamics in soft materials: The term single file (SF) dynamics refers to the motion of an assembly of\nparticles through a channel with cross-section comparable to the particles'\ndiameter. Single file diffusion (SFD) is then the diffusion of a tagged\nparticle in a \\emph{single file}, i.e., under the condition that particle\npassing is not allowed. SFD accounts for a large variety of processes in\nnature, including diffusion of colloids in synthetic and natural-shaped\nchannels, biological motors along molecular chains, electrons in proteins and\nliquid helium, ions through membrane, just to mention a few examples. Albeit\nintroduced in '65, over the last decade the classical notion of SF dynamics has\nbeen generalized to account through a more realistic modeling of, among others,\nparticles properties, file geometry, particle-particle and channel-particles\ninteractions, thus paving the way to remarkable applications in, for example,\nthe technology of bio-integrated nanodevices. We then provide a comprehensive\nreview of the recent advances in the theory of SF dynamics and the ensuing\nexperimental realisations."
    },
    {
        "anchor": "Measurements of the aeolian sand transport saturation length: The wavelength at which a dune pattern emerges from a flat sand bed is\ncontrolled by the sediment transport saturation length, which is the length\nneeded for the sand flux to adapt to a change of wind strength. The influence\nof the wind shear velocity on this saturation length and on the subsequent dune\ninitial wavelength has remained controversial. In this letter, we present\ndirect measurements of the saturation length performed in a wind tunnel\nexperiment. In complement, initial dune wavelengths are measured under\ndifferent wind conditions -- in particular after storms. Using the linear\nstability analysis of dune formation, it is then possible to deduce the\nsaturation length from field data. Both direct and indirect measurements agree\nthat the saturation length is almost independent of the wind strength. This\ndemonstrates that, in contrast with erosion, grain inertia is the dominant\ndynamical mechanism limiting sediment transport saturation.",
        "positive": "Shear-induced rigidity of frictional particles: Analysis of emergent\n  order in stress space: Solids are distinguished from fluids by their ability to resist shear. In\ntraditional solids, the resistance to shear is associated with the emergence of\nbroken translational symmetry as exhibited by a non-uniform density pattern,\nwhich results from either minimizing the energy cost or maximizing the entropy\nor both. In this work, we focus on a class of systems, where this paradigm is\nchallenged. We show that shear-driven jamming in dry granular materials is a\ncollective process controlled solely by the constraints of mechanical\nequilibrium. We argue that these constraints lead to a broken translational\nsymmetry in a dual space that encodes the statistics of contact forces and the\ntopology of the contact network. The shear-jamming transition is marked by the\nappearance of this broken symmetry. We extend our earlier work, by comparing\nand contrasting real space measures of rheology with those obtained from the\ndual space. We investigate the structure and behavior of the dual space as the\nsystem evolves through the rigidity transition in two different shear\nprotocols. We analyze the robustness of the shear-jamming scenario with respect\nto protocol and packing fraction, and demonstrate that it is possible to define\na protocol-independent order parameter in this dual space, which signals the\nonset of rigidity."
    },
    {
        "anchor": "Multi-mode active control of friction, dynamic ratchets and actuators: Active control of friction by ultrasonic vibration is a well-known effect\nwith numerous technical applications ranging from press forming to\nmicromechanical actuators. Reduction of friction is observed with vibration\napplied in any of the three possible directions (normal to the contact plane,\nin the direction of motion and in-plane transverse). In this work, we consider\nthe multi-mode active control of sliding friction, where phase-shifted\noscillations in two or more directions act at the same time. Our analysis is\nbased on a macroscopic contact-mechanical model that was recently shown to be\nwell-suited for describing dynamic frictional processes. For simplicity, we\nlimit our analysis to a constant, load-independent normal and tangential\nstiffness and two superimposed phase-shifted harmonic oscillations, one of them\nbeing normal to the plane and the other in the direction of motion. As in\nprevious works utilizing the present model, we assume a constant local\ncoefficient of friction, with reduction of the observed force of friction\narising entirely from the macroscopic dynamics of the system. Our numerical\nsimulations show that the resulting law of friction is determined by just three\ndimensionless parameters. Depending on the values of these parameters, three\nqualitatively different types of behavior are observed: (a) symmetric\nvelocity-dependence of the coefficient of friction (same for positive and\nnegative velocities), (b) asymmetric dependence with respect to the sign of the\nvelocity, but with zero force at zero velocity, and (c) asymmetric dependence\nwith non-zero force at zero velocity. The latter two cases can be interpreted\nas a \"dynamic ratchet\" (b) and an actuator (c).",
        "positive": "Periodic and Quasiperiodic Motion of an Elongated Microswimmer in\n  Poiseuille Flow: We study the dynamics of a prolate spheroidal microswimmer in Poiseuille flow\nfor different flow geometries. When moving between two parallel plates or in a\ncylindrical microchannel, the swimmer performs either periodic swinging or\nperiodic tumbling motion. Although the trajectories of spherical and elongated\nswimmers are qualitatively similar, the swinging and tumbling frequency\nstrongly depends on the aspect ratio of the swimmer. In channels with reduced\nsymmetry the swimmers perform quasiperiodic motion which we demonstrate\nexplicitely for swimming in a channel with elliptical cross section."
    },
    {
        "anchor": "Near-wall hydrodynamic slip triggers swimming state transition of\n  microorganisms: Interaction of motile microrganisms with a nearby solid substrate is a well\nstudied phenomenon. However, the effects of hydrodynamic slippage on the\nsubstrate have received a little attention. In the present study, within the\nframework of the squirmer model, we impose a tangential velocity at the swimmer\nsurface as a representation of the ciliatory propulsion and subsequently obtain\nexact solution of the Stokes equation based on a combined analytical-numerical\napproach. We illustrate how the near-wall swimming velocities are non-trivially\naltered by the interaction of wall slip and hydrodynamic forces. We report a\ncharacteristic transition of swimming trajectories for both puller and pusher\ntype microswimmers by hydrodynamic slippage if the wall-slip length crosses a\ncritical value. In case of puller microswimmers that are propelled by a\nbreast-stroke like action of their swimming apparatus ahead of their cell body,\nthe wall slip can cause wall-bound trapping swimming states, either as periodic\nor damped periodic oscillations which would otherwise escape from a no slip\nwall. The associated critical slip length has a non-monotonic dependence on the\ninitial orientation of the swimmer which is represented by novel phase\ndiagrams. Pushers, which get their propulsive thrust from posterior flagellar\naction, also show similar swimming state transitions but in this case the wall\nslip mediated reorientation dynamics and the swimming modes compete in a\ndifferent fashion to that of the pullers. The present results pave the way for\nunderstanding the motion characteristic of biological microswimmers near\nconfinements with hydrophobic walls or strategize the design of microfluidic\ndevices used for sorting and motion rectification of artificial swimmers by\ntailoring their surface wettability.",
        "positive": "A Single Nucleotide Resolution Model for Large-Scale Simulations of\n  Double Stranded DNA: The computational modelling of DNA is becoming crucial in light of new\nadvances in DNA nanotechnology, single-molecule experiments and in vivo DNA\ntampering. Here we present a mesoscopic model for double stranded DNA (dsDNA)\nat the single nucleotide level which retains the characteristic helical\nstructure, while being able to simulate large molecules -- up to a million base\npairs -- for time-scales which are relevant to physiological processes. This is\nmade possible by an efficient and highly-parallelised implementation of the\nmodel which we discuss here. We compare the behaviour of our model with single\nmolecule experiments where dsDNA is manipulated by external forces or torques.\nWe also present some results on the kinetics of denaturation of linear DNA."
    },
    {
        "anchor": "Active Brownian particles moving in a random Lorentz gas: Biological microswimmers often inhabit a porous or crowded environment such\nas soil. In order to understand how such a complex environment influences their\nspreading, we numerically study non-interacting active Brownian particles\n(ABPs) in a two-dimensional random Lorentz gas. Close to the percolation\ntransition in the Lorentz gas, they perform the same subdiffusive motion as\nballistic and diffusive particles. However, due to their persistent motion they\nreach their long-time dynamics faster than passive particles and also show\nsuperdiffusive motion at intermediate times. While above the critical obstacle\ndensity $\\eta_c$ the ABPs are trapped, their long-time diffusion below $\\eta_c$\nis strongly influenced by the propulsion speed $v_0$. With increasing $v_0$,\nABPs are stuck at the obstacles for longer times. Thus, for large propulsion\nspeed, the long-time diffusion constant decreases more strongly in a denser\nobstacle environment than for passive particles. This agrees with the behavior\nof an effective swimming velocity and persistence time, which we extract from\nthe velocity autocorrelation function.",
        "positive": "Asymptotic decay of pair correlations in a Yukawa fluid: We analyse the $r \\to \\infty$ asymptotic decay of the total correlation\nfunction, $h(r)$, for a fluid composed of particles interacting via a (point)\nYukawa pair potential. Such a potential provides a simple model for dusty\nplasmas. The asymptotic decay is determined by the poles of the liquid\nstructure factor in the complex plane. We use the hypernetted-chain closure to\nthe Ornstein-Zernike equation to determine the line in the phase diagram,\nwell-removed from the freezing transition line, where crossover occurs in the\nultimate decay of $h(r)$, from monotonic to damped oscillatory. We show: i)\ncrossover takes place via the same mechanism (coalescence of imaginary poles)\nas in the classical one-component plasma and in other models of Coulomb fluids\nand ii) leading-order pole contributions provide an accurate description of\n$h(r)$ at intermediate distances $r$ as well as at long range."
    },
    {
        "anchor": "Computing Counterion Densities at Intermediate Coupling: By decomposing the Coulomb interaction into a long distance component\nappropriate for mean-field theory, and a nonmean-field short distance\ncomponent, we compute the counterion density near a charged surface for all\nvalues of the counterion coupling parameter. A modified strong-coupling\nexpansion that is manifestly finite at all coupling strengths is used to treat\nthe short distance component. We find a nonperturbative correction related to\nthe lateral counterion correlations that modifies the density at intermediate\ncoupling.",
        "positive": "Lattice Model of an Ionic Liquid at an Electrified Interface: We study ionic liquids interacting with electrified interfaces. The ionic\nfluid is modeled as a Coulomb lattice gas. We compare the ionic density\nprofiles calculated using a popular modified Poisson-Boltzmann equation with\nthe explicit Monte Carlo simulations. The modified Poisson-Boltzmann theory\nfails to capture the structural features of the double layer and is also unable\nto correctly predict the ionic density at the electrified interface. The\nlattice Monte Carlo simulations qualitatively capture the coarse-grained\nstructure of the double layer in the continuum. We propose a convolution\nrelation that semiquantitatively relates the ionic density profiles of a\ncontinuum ionic liquid and its lattice counterpart near an electrified\ninterface."
    },
    {
        "anchor": "Chiral propulsion by electromagnetic fields: We consider the propulsion of micron-scale chiral objects by electromagnetic\nfields in fluids - a problem with broad applications in microfluidics,\npharmaceutics, and biomedicine. Because of the small size of the moving\nobjects, the propulsion can be described by the Stokes equation possessing the\ntime-reversal invariance. We propose a method of evaluating the propulsion\nvelocity based on the Green's function of the Stokes equation. As an\nillustration, we first use it to provide a simple derivation of the classic\nStokes law for a sphere moving in a viscous fluid. We then use this method for\ndescribing the propulsion of helical bodies, evaluate the propulsion velocity,\nand find that it does not depend on the viscosity of the fluid as long as the\nReynolds number remains small. As an application, we describe recent\nexperimental results on the propulsion of nano-propellers by electromagnetic\nfields in water, with a good agreement with the data. We also discuss\napplications to optofluidic chiral sorting of molecules by rotating\nelectromagnetic fields and circularly polarized light.",
        "positive": "Viscoelastic dynamics of a soft strip subject to a large deformation: To produce sounds, we adjust the tension of our vocal folds to shape their\nproperties and control the pitch. This efficient mechanism offers inspiration\nfor designing reconfigurable materials and adaptable soft robots. However,\nunderstanding how flexible structures respond to a significant static strain is\nnot straightforward. This complexity also limits the precision of medical\nimaging when applied to tensioned organs like muscles, tendons, ligaments and\nblood vessels among others. In this article, we experimentally and\ntheoretically explore the dynamics of a soft strip subject to a substantial\nstatic extension, up to 180%. Our observations reveal a few intriguing effects,\nsuch as the resilience of certain vibrational modes to a static deformation.\nThese observations are supported by a model based on the incremental\ndisplacement theory. This has promising practical implications for\ncharacterizing soft materials but also for scenarios where external actions can\nbe used to tune properties."
    },
    {
        "anchor": "The Physics of Granular Mechanics: The {\\em hydrodynamic} approach to a continuum mechanical description of\ngranular behavior is reviewed and elucidated. By considering energy and\nmomentum conservation simultaneously, the general formalism of {\\em\nhydrodynamics} provides a systematic method to {derive} the structure of\nconstitutive relations, including all gradient terms needed for nonuniform\nsystems. An important input to arrive at different relations (say, for\nNewtonian fluid, solid and granular medium) is the energy, especially the\nnumber and types of its variables.\n  Starting from a careful examination of the physics underlying granular\nbehavior, we identify the independent variables and suggest a simple and\nqualitatively appropriate expression for the granular energy. The resultant\nhydrodynamic theory, especially the constitutive relation, is presented and\ngiven preliminary validation.",
        "positive": "The dielectric response of spherical live cells in suspension: An\n  analytic solution: We develop a theoretical framework to describe the dielectric response of\nlive cells in suspensions when placed in low external electric fields. The\ntreatment takes into account the presence of the cell's membrane and of the\ncharge movement at the membrane's surfaces. For spherical cells suspended in\naqueous solutions, we give an analytic solution for the dielectric function,\nwhich is shown to account for the alpha and beta plateaus seen in many\nexperimental data. The effect of different physical parameters on the\ndielectric curves is methodically analyzed."
    },
    {
        "anchor": "Intermediate DNA at low added salt: DNA bubbles slow the diffusion of\n  short DNA fragments: We report a study of DNA (150 bp fragments) conformations in very low added\nsalt $<0.05$mM, across wide DNA concentration range $0.0015\\leq c \\leq 8$~mM\n(bp). We found an intermediate DNA conformation in the region $0.05 < c <\n1$~mM, by means of fluorescence correlation spectroscopy (FCS) and\nUV-absorbance measurements. FCS detected that in this region DNA has the\ndiffusion coefficient, $D_p$ reduced below the values for both ssDNA coils and\nnative dsDNA helices of similar polymerization degree $N$. Thus, this DNA\npopulation can not be a simple mix of dsDNA and of ssDNA which results from DNA\nmelting. Here, melting occurs due to a reduction in screening concomitant with\nDNA concentration being reduced, in already very low salt conditions. The\nintermediate DNA is rationalized through the well known concept of\nfluctuational openings (DNA bubbles) which we postulate to form in AT-rich\nportions of the sequence, without the strands coming apart. Within the bubbles,\nDNA is locally stretched, while the whole molecule remains rod-like due to very\nlow salt environment. Therefore, such intermediate DNA is elongated, in\ncomparison to dsDNA, which accounts for its reduced $D_p$.",
        "positive": "Nematic--to--Smectic-A Transition in Aerogel: We study a model for the Nematic--Smectic-A (NA) transition in aerogel, and\nfind that even arbitrarily weak quenched disorder (i.e., low aerogel density)\ndestroys translational (smectic) order. Ignoring elastic anharmonicities, but\nkeeping anharmonic couplings to disorder, leads to the prediction that there is\nno ``Bragg glass'' phase in this system: it is riddled with dislocation loops\ninduced by the quenched disorder. Orientational (nematic) order is destroyed as\nwell, as is the thermodynamically sharp NA transition, in agreement with recent\nexperimental results."
    },
    {
        "anchor": "Fluctuation of the Top Location and Avalanches in the Formation Process\n  of a Sandpile: We investigate the formation processes of a sandpile using numerical\nsimulation. We find a new relation between the fluctuation of the motion of the\ntop and the surface state of a sandpile. The top moves frequently as particles\nare fed one by one every time interval T. The time series of the top location\nhas the power spectrum which obeys a power law, S(f)~f^{\\alpha}, and its\nexponent \\alpha depends on T and the system size w. The surface state is\ncharacterized by two time scales; the lifetime of an avalanche, T_{a}, and the\ntime required to cause an avalanche, T_{s}. The surface state is fluid-like\nwhen T_{a}~T_{s}, and it is solid-like when T_{a}<<T_{s}. Our numerical results\nshow that \\alpha is a function of T_{s}/T_{a}.",
        "positive": "Active dislocations and topological traps govern dynamics of spiraling\n  filamentous cyanobacteria: Activity can organize matter in unique configurations inaccessible to\nequilibrium systems, including a sundry of spiraling shapes seen in nature that\nrange from galaxies to living tissues to fossilized stromatolites. How these\ndynamic yet stable patterns form in motile active systems that span a range of\nlength and time scales remains an open question. Here we study the collective\ngliding dynamics of ultra-long filamentous cyanobacteria confined in two\ndimensions and present the discovery of an emergent pattern we call ``active\nspirals\". Individual filaments in the spiral bulk remain confluent due to\nadhesion forces and exhibit reversible gliding motility. Thus individual\nfilaments undergo bidirectional movement and the spiral object as a whole has\nno fixed vorticity. Using single filament tracking, we discover that spirals\npermit the radial flux of material as filaments shear past one another. We\ndemonstrate that these rearrangements can be entirely described by topological\nrules of interaction between filaments tips. We thus reduce the dynamics of a\nspiral to a set of active dislocations (corresponding to the filament tips) on\na polar coordinate lattice and show that we can reproduce and predict the\nmaterial flux in the system. Finally, we present a discovery of a novel\ntopological trap present in these spirals, and is induced purely by the\ngeometric chirality of long winding filaments with winding number greater than\nzero. A topological trap creates boundaries in the spiral across which material\ncannot flow, leading to persistent structures that are topologically locked for\nthe lifetime of the system. The emergent mechanics of active spirals presented\nhere sheds light on the critical role of adhesion forces, activity and geometry\nin the formation of long-term, stable, yet dynamic active patterns."
    },
    {
        "anchor": "The influence of van der Waals forces on droplet morphological\n  transitions and solvation forces in nanochannels: The morphological phase transition between a sessile and lenticular shapes of\na droplet placed in a nanochannel is observed upon increasing the droplet\nvolume. The phase diagram for this system is discussed within the macro- and\nmesoscopic approaches. On the mesoscopic level, the van der Waals forces are\ntaken into account via the effective interface potential acting between the\nchannel walls and the droplet. We discuss the contact angle dependence on the\ndroplet volume and the distance between the walls; this angle turns out to be\nsmaller than the macroscopic Young's angle. The droplet presence induces the\nsolvation force acting between the channel walls. It can be both attractive and\nrepulsive, depending on the width of the channel.",
        "positive": "Biomimetic isotropic nanostructures for structural coloration: We describe the self-assembly of biomimetic isotropic films which display\nstructural color amenable to potential applications in coatings. Isotropic\nstructures can produce color if there is a pronounced characteristic\nlength-scale comparable to the wavelength of visible light and\nwavelength-independent scattering is suppressed."
    },
    {
        "anchor": "Experimental Test on Edwards Volume Ensemble of Tapped Granular Packings: Using X-ray tomography, we experimentally investigate granular packings\nsubject to mechanical tapping for three types of beads with different friction\ncoefficients. We validate Edwards volume ensemble in these three-dimensional\ngranular systems and establish a granular version of thermodynamic zeroth law.\nWithin Edwards framework, we also explicitly clarify how friction influences\ngranular statistical mechanics as modifying the density of states, which allows\nus to determine the entropy as a function of packing fraction and friction\nsubsequently. Additionally, we obtain a granular jamming phase diagram based on\ngeometric coordination number and packing fraction.",
        "positive": "Modelling and measurements of fibrinogen adsorption on positively\n  charged microspheres: Adsorption of fibrinogen on positively charged microspheres was theoretically\nand experimentally studied. The structure of monolayers and the maximum\ncoverage were determined by applying the experimental measurements at pH=3.5\nand 9.7 for NaCl concentration in the range of $10^{-3}- 0.15$ M. The maximum\ncoverage of fibrinogen on latex particles was precisely determined by the AFM\nmethod. Unexpectedly, at pH=3.5, where both fibrinogen molecule and the latex\nparticles were positively charged, the maximum coverage varied between 0.9 mg\nm$^{-2}$ and 1.1 mg m$^{-2}$ for $10^{-2}$ and 0.15 M NaCl, respectively. On\nthe other hand, at pH=9.7, the maximum coverage of fibrinogen was larger,\nvarying between 1.8 mg m$^{-2}$ and 3.4 mg m$^{-2}$ for $10^{-2}$ and 0.15 M\nNaCl, respectively. The experimental results were quantitatively interpreted by\nthe numerical simulations."
    },
    {
        "anchor": "Soft and non-soft structural transitions in disordered nematic networks: Properties of disordered nematic elastomers and gels are theoretically\ninvestigated with emphasis on the roles of non-local elastic interactions and\ncrosslinking conditions. Networks originally crosslinked in the isotropic phase\nlose their long-range orientational order by the action of quenched random\nstresses, which we incorporate into the affine-deformation model of nematic\nrubber elasticity. We present a detailed picture of mechanical quasi-Goldstone\nmodes, which accounts for an almost completely soft polydomain-monodomain (P-M)\ntransition under strain as well as a ``four-leaf clover'' pattern in\ndepolarized light scattering intensity. Dynamical relaxation of the domain\nstructure is studied using a simple model. The peak wavenumber of the structure\nfactor obeys a power-law-type slow kinetics and goes to zero in true mechanical\nequilibrium. The effect of quenched disorder on director fluctuation in the\nmonodomain state is analyzed. The random frozen contribution to the fluctuation\namplitude dominates the thermal one, at long wavelengths and near the P-M\ntransition threshold. We also study networks obtained by crosslinking\npolydomain nematic polymer melts. The memory of initial director configuration\nacts as correlated and strong quenched disorder, which renders the P-M\ntransition non-soft. The spatial distribution of the elastic free energy is\nstrongly dehomogenized by external strain, in contrast to the case of\nisotropically crosslinked networks.",
        "positive": "The correlation between fragility, density and atomic interaction in\n  glass-forming liquids: The fragility, that controls the temperature-dependent viscous properties of\nliquids as the glass transition is approached, in various glass-forming liquids\nwith different atomic interactions and densities is investigated by molecular\ndynamic simulations. We show the landscape of fragility in purely repulsive\nsystems can be separated into three regions with qualitatively disparate\ndynamic behaviors, suggesting that the density plays an unexpected role for\nunderstanding the repulsive steepness dependence of fragility. Furthermore, the\nvastly dissimilar influences of attractive interaction on fragility could be\nestimated from the structural properties of related zero-temperature glasses"
    },
    {
        "anchor": "Dynamic Fluctuation Phenomena in Double Membrane Films: Dynamics of double membrane films is investigated in the long-wavelength\nlimit including the overdamped squeezing mode. We demonstrate that thermal\nfluctuations essentially modify the character of the mode due to its nonlinear\ncoupling to the transversal shear hydrodynamic mode. The corresponding Green\nfunction acquires as a function of the frequency a cut along the imaginary\nsemi-axis. Fluctuations lead to increasing the attenuation of the squeezing\nmode it becomes larger than the `bare' value.",
        "positive": "Brownian dynamics simulations of planar mixed flows of polymer solutions\n  at finite concentrations: Periodic boundary conditions for planar mixed flows are implemented in the\ncontext of a multi-chain Brownian dynamics simulation algorithm. The effect of\nshear rate $\\dot{\\gamma}$, and extension rate $\\dot{\\epsilon}$, on the size of\npolymer chains, $\\left<R_e^2\\right>$, and on the polymer contribution to\nviscosity, $\\eta$, is examined for solutions of FENE dumbbells at finite\nconcentrations, with excluded volume interactions between the beads taken into\naccount. The influence of the mixedness parameter, $\\chi$, and flow strength,\n$\\dot{\\Gamma}$, on $\\left<R_e^2\\right>$ and $\\eta$, is also examined, where\n$\\chi \\rightarrow 0$ corresponds to pure shear flow, and $\\chi \\rightarrow 1$\ncorresponds to pure extensional flow. It is shown that there exists a critical\nvalue, $\\chi_\\text{c}$, such that the flow is shear dominated for $\\chi <\n\\chi_\\text{c}$, and extension dominated for $\\chi > \\chi_\\text{c}$."
    },
    {
        "anchor": "Non-equilibrium fluctuations and nonlinear response of an active bath: We analyze the dynamics of a passive colloidal probe immersed in an active\nbath using an optical trap to study three physical processes: (1) the\nnon-equilibrium fluctuations transferred to the probe by the active bath, (2)\nthe friction experienced by the probe as it is driven through the active bath,\nand (3) the force relaxation of the probe returning to its equilibrium\nposition. We measure the local force dynamics where all of the following\ncharacteristics are of $\\mathcal{O}(1)$: the size of the probe colloid relative\nto active bath particle; the size of the probe colloid relative to the\ncharacteristic run-length of an active particle; and the timescale of probe\nmovement to the persistence time of an active particle. We find at P\\'{e}clet\n(Pe) $\\ll 1$ the active suspension exhibits shear thinning down to the solvent\nviscosity (but not below); at $0.85 <$ Pe $\\leq 5.1$ the active bath shear\nthickens; and at Pe $\\geq 8.5$ the effective viscosity of the active bath shows\na decreased effect of thickening and plateaus. These results are in agreement\nwith recent modeling and simulations of the nonlinear rheology of an isotropic\nactive bath, providing experimental verification, and suggesting the model\npredictions extends to moderately dense suspensions. Further, we observe that\nthe distribution of force fluctuations depends on Pe, unlike in passive\nequilibrium baths. Lastly, we measure the energy transfer rate from the active\nbath to the probe to be $\\langle J \\rangle \\approx 10^3$ $k_B T/$s, which leads\nto an increase in the effective diffusion of the probe by a factor of $\\sim 2$.",
        "positive": "Atomic Scale Interfacial Transport at an Extended Evaporating Meniscus: Recent developments in fabrication techniques enabled the production of nano-\nand angstrom-scale conduits. While scientists are able to conduct experimental\nstudies to demonstrate extreme evaporation rates from these capillaries,\ntheoretical modeling of evaporation from a few nanometers or sub-nanometer\nmeniscus interfaces, where adsorbed film, transition film and intrinsic region\nare intertwined, is absent in the literature. Using the computational setup\nconstructed to identify the detailed profile of a nano-scale evaporating\ninterface, we discovered the existence of lateral momentum transport within and\nassociated net evaporation from adsorbed liquid layers, which are long believed\nto be at the equilibrium established between equal rates of evaporation and\ncondensation. Contribution of evaporation from the adsorbed layer increases the\neffective evaporation area, reducing the excessively estimated evaporation flux\nvalues. This work takes the first step towards a comprehensive understanding of\natomic/molecular scale interfacial transport at extended evaporating menisci.\nThe modeling strategy used in this study opens an opportunity for computational\nexperimentation of steady-state evaporation and condensation at liquid/vapor\ninterfaces located in capillary nano-conduits."
    },
    {
        "anchor": "Epigenetics as a first exit problem: We develop a framework to discuss stability of epigenetic states as first\nexit problems in dynamical systems with noise. We consider in particular the\nstability of the lysogenic state of the lambda prophage, which is known to\nexhibit exceptionally large stability. The formalism defines a quantative\nmeasure of robustness of inherited states.\n  In contrast to Kramers' well-known problem of escape from a potential well,\nthe stability of inherited states in our formulation is not a numerically\ntrivial problem. The most likely exit path does not go along a steepest decent\nof a potential -- there is no potential. Instead, such a path can be described\nas a zero-energy trajectory between two equilibria in an auxiliary classical\nmechanical system. Finding it is similar to e.g. computing heteroclinic orbits\nin celestial mechanics. The overall lesson of this study is that an examination\nof equilibria and their bifurcations with changing parameter values allow us to\nquantify both the stability and the robustness of particular states of a\ngenetic control system.",
        "positive": "Tunable topological phase transition in soft Rayleigh beam system with\n  imperfect interfaces: Acoustic metamaterials, particularly the topological insulators, exhibit\nexceptional wave characteristics that have sparked considerable research\ninterest. The study of imperfect interfaces affect is of significant importance\nfor the modeling of wave propagation behavior in topological insulators. This\npaper models a soft Rayleigh beam system with imperfect interfaces, and\ninvestigates its topological phase transition process tuned by mechanical\nloadings. The model reveals that the topological phase transition process can\nbe observed by modifying the distance between imperfect interfaces in the\nsystem. When a uniaxial stretch is applied, the topological phase transition\npoints for longitudinal waves decrease within a limited frequency range, while\nthey increase within a larger frequency scope for transverse waves. Enhancing\nthe rigidity of the imperfect interfaces also enables shifting of the\ntopological phase transition point within a broader frequency range for\nlongitudinal waves and a confined range for transverse waves. The transition of\ntopologically protected interface modes in the transmission performance of a\ntwenty-cell system is verified, which include altering frequencies, switching\nfrom interface mode to edge mode. Overall, this study provides a new approach\nand guideline for controlling topological phase transition in composite and\nsoft phononic crystal systems."
    },
    {
        "anchor": "\"Wet-to-Dry\" Conformational Transition of Polymer Layers Grafted to\n  Nanoparticles in Nanocomposite: The present communication reports the first direct measurement of the\nconformation of a polymer corona grafted around silica nano-particles dispersed\ninside a nanocomposite, a matrix of the same polymer. This measurement\nconstitutes an experimental breakthrough based on a refined combination of\nchemical synthesis, which permits to match the contribution of the neutron\nsilica signal inside the composite, and the use of complementary scattering\nmethods SANS and SAXS to extract the grafted polymer layer form factor from the\ninter-particles silica structure factor. The modelization of the signal of the\ngrafted polymer on nanoparticles inside the matrix and the direct comparison\nwith the form factor of the same particles in solution show a clear-cut change\nof the polymer conformation from bulk to the nanocomposite: a transition from a\nstretched and swollen form in solution to a Gaussian conformation in the matrix\nfollowed with a compression of a factor two of the grafted corona. In the\nprobed range, increasing the interactions between the grafted particles (by\nincreasing the particle volume fraction) or between the grafted and the free\nmatrix chains (decreasing the grafted-free chain length ratio) does not\ninfluence the amplitude of the grafted brush compression. This is the first\ndirect observation of the wet-to-dry conformational transition theoretically\nexpected to minimize the free energy of swelling of grafted chains in\ninteraction with free matrix chains, illustrating the competition between the\nmixing entropy of grafted and free chains, and the elastic deformation of the\ngrafted chains. In addition to the experimental validation of the theoretical\nprediction, this result constitutes a new insight for the nderstanding of the\ngeneral problem of dispersion of nanoparticles inside a polymer matrix for the\ndesign of new nanocomposites materials.",
        "positive": "Dense granular flows: interpolating between grain inertia and fluid\n  viscosity based constitutive laws: A scalar constitutive law was recently obtained for dense granular flows from\na two-grain argument, both in the inertial regime (grain inertia) and in the\nviscous regime. As the resulting law is not exactly the same in both regimes,\nwe here provide an expression for the crossover between both regimes."
    },
    {
        "anchor": "Molecular dynamics study of nanoconfined TIP4P/2005 water: how\n  confinement and temperature affect diffusion and viscosity: In the last decades a large effort has been devoted to the study of water\nconfined in hydrophobic geometries at the nanoscale (tubes, slit pores),\nbecause of the multiple technological applications of such systems, ranging\nfrom drugs delivery to water desalinization devices. To our knowledge, neither\nnumerical/theoretical nor experimental approaches have so far reached a\nconsensual understanding of structural and transport properties of water under\nthese conditions. In this work, we present molecular dynamics simulations of\nTIP4P/2005 water under different hydrophobic nano-confinements (slit pores or\nnanotubes, with two degrees of hydrophobicity) within a wide temperature range.\nOn the one side, water is more structured near the hydrophobic walls,\nindependently on the confining geometries. On the other side, we show that the\ncombined effect of confinement and curvature leads to an enhanced diffusion\ncoefficient of water in hydrophobic nanotubes. Finally, we propose a confined\nStokes-Einstein relation to extract viscosity from diffusivity, whose result\nstrongly differs from the Green-Kubo expression that has been used in previous\nwork. We discuss the shortcomings of both approaches, which could explain this\ndiscrepancy.",
        "positive": "Bifurcation of Stretched Exponential Relaxation in Microscopically\n  Homogeneous Glasses: Measured exponents associated with Stretched Exponential Relaxation (SER) are\nwidely scattered in microscopically inhomogeneous glasses, but accurately\nbifurcate into two \"magic\" values, 3/5 and 3/7, in a wide variety of\nmicroscopically homogeneous glasses. These bifurcated values are derived here\nfrom a statistical product model that involves diffusion of excitations to\nnative traps in the presence of short-range forces only, or combined short- and\nlong- range forces, respectively. Bifurcated SER can be used to monitor sample\nhomogeneity. It explains a wide range of experimental data, and even includes\nmultiple aspects of the citation distributions of 20th century science,\ninvolving 25 million papers and 600 million citations, and why these changed\nradically in 1960. It also shows that the distribution of country population\nsizes has compacted glassy character, and is strongly influenced by migration."
    },
    {
        "anchor": "Thermal Fluctuations For a Three-Beads Swimmer: We discuss a micro-swimmer model made of three spheres actuated by an\ninternal active time-periodic force, tied by an elastic potential and submitted\nto hydrodynamic interactions with thermal noise. The dynamical approach we use,\nreplacing the more common kinetic one, unveils the instability of the original\nmodel and the need of a confining potential to prevent the evaporation of the\nswimmer. We investigate the effect of the main parameters of the model, such as\nthe frequency and phase difference of the periodic active force, the stiffness\nof the confining potential, the length of the swimmer and the temperature and\nviscosity of the fluid. Our observables of interest are the averages of the\nswim velocity, of the energy consumption rate, the diffusion coefficient and\nthe swimming precision, which is limited by the energy consumption through the\ncelebrated Thermodynamic Uncertainty Relations. An optimum for velocity and\nprecision is found for an intermediate frequency. Reducing the potential\nstiffness, the viscosity or the length, is also beneficial for the swimming\nperformance, but these parameters are limited by the consistency of the model.\nAnalytical approximation for many of the interesting observables is obtained\nfor small deformations of the swimmer. We also discuss the efficiency of the\nswimmer in terms of its maximum precision and of the hydrodynamic, or\nLighthill, criterion, and how they are connected.",
        "positive": "Clogging, Dynamics and Reentrant Fluid for Active Matter on Periodic\n  Substrates: We examine the collective states of run-and-tumble active matter disks driven\nover a periodic obstacle array. When the drive is applied along a symmetry\ndirection of the array, we find a clog-free uniform liquid state for low\nactivity, while at higher activity, the density becomes increasingly\nheterogeneous and an active clogged state emerges in which the mobility is\nstrongly reduced. For driving along non-symmetry or incommensurate directions,\nthere are two different clogging behaviors consisting of a drive dependent\nclogged state in the low activity thermal limit and a drive independent clogged\nstate at high activity. These regimes are separated by a uniform flowing liquid\nat intermediate activity. There is a critical activity level above which the\nthermal clogged state does not occur, as well as an optimal activity level that\nmaximizes the disk mobility. Thermal clogged states are dependent on the\ndriving direction while active clogged states are not. In the low activity\nregime, diluting the obstacles produces a monotonic increase in the mobility;\nhowever, for large activities, the mobility is more robust against obstacle\ndilution. We also examine the velocity-force curves for driving along\nnon-symmetry directions, and find that they are linear when the activity is low\nor intermediate, but become nonlinear at high activity and show behavior\nsimilar to that found for the plastic depinning of solids. At higher drives the\nactive clustering is lost. For low activity we also find a reentrant fluid\nphase, where the system transitions from a high mobility fluid at low drives to\na clogged state at higher drives and then back into another fluid phase at very\nhigh drives. We map the regions in which the thermally clogged, partially\nclogged, active uniform fluid, clustered fluid, active clogged, and\ndirectionally locked states occur as a function of disk density, drift force,\nand activity."
    },
    {
        "anchor": "Dynamics of nearly spherical vesicles in an external flow: We analytically derive an equation describing vesicle evolution in a fluid\nwhere some stationary flow is excited regarding that the vesicle shape is close\nto a sphere. A character of the evolution is governed by two dimensionless\nparameters, $S$ and $\\Lambda$, depending on the vesicle excess area, viscosity\ncontrast, membrane viscosity, strength of the flow, bending module, and ratio\nof the elongation and rotation components of the flow. We establish the ``phase\ndiagram'' of the system on the $S-\\Lambda$ plane: we find curves corresponding\nto the tank-treading to tumbling transition (described by the saddle-node\nbifurcation) and to the tank-treading to trembling transition (described by the\nHopf bifurcation).",
        "positive": "From Motility-Induced Phase-Separation to Glassiness in Dense Active\n  Matter: Dense active systems are widespread in nature, examples range from bacterial\ncolonies to biological tissues. Dense clusters of active particles can be\nobtained by increasing the packing fraction of the system or taking advantage\nof a peculiar phenomenon named motility-induced phase separation (MIPS). In\nthis work, we explore the phase diagram of a two-dimensional model of active\nglass and show that disordered active materials develop a rich collective\nbehaviour encompassing both MIPS and glassiness. We find that, although the\nglassy state is almost indistinguishable from that of equilibrium glasses, the\nmechanisms leading to its fluidization do not have any equilibrium counterpart.\nOur results can be rationalized in terms of a crossover between a low-activity\nregime, where glassy dynamics is controlled by an effective temperature, and a\nhigh-activity regime, which drives the system towards MIPS."
    },
    {
        "anchor": "Critical bending and magnetic shape memory effect in magnetoactive\n  elastomers: The results of a study of magnetoactive elastomers (MAEs) consisting of an\nelastomer matrix with embedded ferromagnetic particles are presented. A\ncontinuous critical bending induced by the magnetic field, characterized by a\ncritical exponent for the bending magnitude, and the derivative of which has a\nsingularity in the critical region is reported for the first time. The\nmechanical stability loss and the symmetry reduction of the magnetic state,\nwhich are interrelated with each other, take place at the critical point. The\nmagnetization in the high-symmetric state (below the critical point) is\ndirected along the magnetic field and the torque is absent. Above the critical\npoint, the magnetization and the magnetic field are noncollinear and there\narises a torque, which is self-consistent with the bending. The magnetic field\ndependence of the MAE bending was found to have a hysteresis, which is\nassociated with the magneto-rheological effect. The shape memory effect was\nalso obtained for the MAE bending in a cycle consisting of magnetization,\ncooling (at H=/0), and heating (at H=0). The influence of the critical glass\ntransition temperature of the matrix, as well as its melting/solidification\ntemperature, on the magnetic shape memory effect was studied.",
        "positive": "Optimized holographic optical traps: Holographic optical traps use the forces exerted by computer-generated\nholograms to trap, move and otherwise transform mesoscopically textured\nmaterials. This article introduces methods for optimizing holographic optical\ntraps' efficiency and accuracy, and an optimal statistical approach for\ncharacterizing their performance. This combination makes possible real-time\nadaptive optimization."
    },
    {
        "anchor": "Adsorption dynamics of hydrophobically modified polymers at an air-water\n  interface: Using surface-tension measurements, we study the brush-limited adsorption\ndynamics of a range of amphiphilic polymers, PAAH-$\\alpha$-$\\textrm{C}_n$\ncomposed of a poly(acrylic acid) backbone, PAAH, grafted with a fraction\n$\\alpha$ of alkyl moieties, containing either $n=8$ or $n=12$ carbon atoms, at\npH conditions where the PAAH backbone is not charged. At short times, the\nsurface tension decreases more sharply as the degree of grafting increases\nwhile at long times, the adsorption dynamics becomes logarithmic in time and is\nslower as the degree of grafting increases. This logarithmic behavior at long\ntimes indicates the building of a free-energy barrier which grows over time. To\naccount for the observed surface tension evolution with the degree of grafting\nwe propose a scenario, where the free-energy barrier results from both the\ndeformation of the incoming polymer coils and the deformation of the adsorbed\nbrush. Our model involves only two fitting parameters, the monomer size and the\narea needed for one molecule during adsorption and is in agreement with the\nexperimental data. We obtain a reasonable value for the monomer size and find\nan area per adsorbed polymer chain of the order of 1nm$^2$, showing that the\npolymer chains are strongly stretched as they adsorb.",
        "positive": "Dynamical density functional theory: binary phase-separating colloidal\n  fluid in a cavity: The dynamical density functional theory of Marconi and Tarazona [J. Chem.\nPhys., 110, 8032 (1999)], a theory for the non-equilibrium dynamics of the\none-body density profile of a colloidal fluid, is applied to a binary fluid\nmixture of repulsive Gaussian particles confined in a spherical cavity of\nvariable size. For this model fluid there exists an extremely simple Helmholtz\nfree energy functional that provides a remarkably accurate description of the\nequilibrium fluid properties. We therefore use this functional to test the\nassumptions implicit in the dynamical density functional theory, rather than\nany approximations involved in constructing the free energy functional. We find\nvery good agreement between the theory and Brownian dynamics simulations,\nfocusing on cases where the confined fluid exhibits phase separation in the\ncavity. We also present an instructive derivation of the Smoluchowski equation\n(from which one is able to derive the dynamical density functional theory)\nstarting from the Liouville equation -- a fully microscopic treatment of the\ncolloid and solvent particles. This `coarse-graining' is, of course, not exact\nand thus the derivation demonstrates the physical assumptions implicit in the\nSmoluchowski equation and therefore also in the dynamical density functional\ntheory."
    },
    {
        "anchor": "Dynamical Heterogeneities in Grains and Foams: Dynamical heterogeneities have been introduced in the context of the glass\ntransition of molecular liquids and the lengthscale associated with them has\nbeen argued to be at the origin of the observed quasi-universal behaviour of\nglassy systems. Dense amorphous packings of granular media and foams also\nexhibit slow dynamics, intermittency and heterogeneities. We review a number of\nrecent experimental studies of these systems, where one has direct access to\nthe relevant space-time dynamics, allowing for direct visualisations of the\ndynamical heterogeneities. On one hand these visualisations provide a unique\nopportunity to access the microscopic mechanisms responsible for the growth of\ndynamical correlations. On the other hand focussing on the differences in these\nheterogeneities in microscopically different systems allows to discuss the\nrange of the analogies between molecular thermal glasses and athermal glasses\nsuch as granular media and foams. Finally this review is the opportunity to\ndiscuss various approaches to actually extract quantitatively the dynamical\nlengthscale from experimental data.",
        "positive": "Influence of grain bidispersity on dense granular flow in a two\n  dimensional hopper: Discrete element method is conducted to investigate the bidisperse dense\ngranular flow having big and small grains in a two dimensional hopper. A\nhalf-circular dynamical force arch is observed above the outlet and Beverloo's\nlaw is verified to describe the relationship between flow rate and outlet size.\nThe bidisperse flow can reach the maximum flow rate when a small fraction of\nbig grains is added into the monodisperse flow with only small grains. The\ndistributions of contact force, packing fraction and grain velocity indicate\nthat the flow properties in the hopper are closely related to the local flow\ncharacteristics of the key area which almost overlaps with the force arch. The\ninterior packing structures, i.e., ordered arrangement for monodisperse flow\nand disordered arrangement for bidisperse flow, play a dominant role in the\nflow pattern transition from mass flow to funnel flow. The earlier occurrence\nof the transition can effectively increase the grain velocity and therefore\nimprove the flow rate."
    },
    {
        "anchor": "Experimental demonstration of robotic active matter micellization: Active matter composed of self-propelled particles features a fascinating set\nof self-organization phenomena, spanning from motility-induced phase separation\nto phototaxis to topological excitations depending on the nature and parameters\nof the system. In the present Letter, we consider the formation of micelles\nfrom particles with a broken symmetry having a circular back and a sharpened\nnose and moving towards the cusp. As we demonstrate in experiments with robotic\nswarms, such particles can either remain in the isotropic phase or form\nmicelles depending on the location of their center of inertia in accordance\nwith a recent theoretical proposal [T. Kruglov, A. Borisov, Particles 2021\n(2021)]. Crucially, the predicted micellization does not involve any charge\nasymmetry, in contrast to that observed in surfactants, and is governed by an\ninterplay of activity and particle shape asymmetry. This renders the observed\nordering reversible upon switching of the particles' activity and opens the\nroute towards novel applications in tunable structuring of materials.",
        "positive": "Brownian Dynamics of Confined Rigid Bodies: We introduce numerical methods for simulating the diffusive motion of rigid\nbodies of arbitrary shape immersed in a viscous fluid. We parameterize the\norientation of the bodies using normalized quaternions, which are numerically\nrobust, space efficient, and easy to accumulate. We construct a system of\noverdamped Langevin equations in the quaternion representation that accounts\nfor hydrodynamic effects, preserves the unit-norm constraint on the quaternion,\nand is time reversible with respect to the Gibbs-Boltzmann distribution at\nequilibrium. We introduce two schemes for temporal integration of the\noverdamped Langevin equations of motion, one based on the Fixman midpoint\nmethod and the other based on a random finite difference approach, both of\nwhich ensure the correct stochastic drift term is captured in a computationally\nefficient way. We study several examples of rigid colloidal particles diffusing\nnear a no-slip boundary, and demonstrate the importance of the choice of\ntracking point on the measured translational mean square displacement (MSD). We\nexamine the average short-time as well as the long-time quasi-two-dimensional\ndiffusion coefficient of a rigid particle sedimented near a bottom wall due to\ngravity. For several particle shapes we find a choice of tracking point that\nmakes the MSD essentially linear with time, allowing us to estimate the\nlong-time diffusion coefficient efficiently using a Monte Carlo method.\nHowever, in general such a special choice of tracking point does not exist, and\nnumerical techniques for simulating long trajectories, such as the ones we\nintroduce here, are necessary to study diffusion on long timescales."
    },
    {
        "anchor": "Decoupling phenomena in supercooled liquids: Signatures in the energy\n  landscape: A significant deviation from the Debye model of rotational diffusion in the\ndynamics of orientational degrees of freedom in an equimolar mixture of\nellipsoids of revolution and spheres is found to begin precisely at a\ntemperature at which the average inherent structure energy of the system starts\nfalling with drop in temperature. We argue that this onset temperature\ncorresponds to the emergence of the alpha-process as a distinct mode of\norientational relaxation. Equally important, we find that the coupling between\nthe rotational and translational diffusion breaks down at a still lower\ntemperature where a sharp change occurs in the temperature dependence of the\naverage inherent structure energy.",
        "positive": "Ground state of a polydisperse electrorheological solid: Beyond the\n  dipole approximation: The ground state of an electrorheological (ER) fluid has been studied based\non our recently proposed dipole-induced dipole (DID) model. We obtained an\nanalytic expression of the interaction between chains of particles which are of\nthe same or different dielectric constants. The effects of dielectric constants\non the structure formation in monodisperse and polydisperse electrorheological\nfluids are studied in a wide range of dielectric contrasts between the\nparticles and the base fluid. Our results showed that the established\nbody-centered tetragonal ground state in monodisperse ER fluids may become\nunstable due to a polydispersity in the particle dielectric constants. While\nour results agree with that of the fully multipole theory, the DID model is\nmuch simpler, which offers a basis for computer simulations in polydisperse ER\nfluids."
    },
    {
        "anchor": "Folding mechanism of a polymer chain with short-range attractions: We investigate the crystallization of a single, flexible homopolymer chain\nusing transition path sampling (TPS). The chain consists of N identical\nspherical monomers evolved according to Langevin dynamics. While neighboring\nmonomers are coupled via harmonic springs, the non-neighboring monomers\ninteract via a hard core and a short-ranged attractive potential. For a\nsufficiently small interaction range {\\lambda}, the system undergoes a\nfirst-order freezing transition from an expanded, disordered phase to a compact\ncrystalline state. Using a new shooting move tailored to polymers combined with\na committor analysis, we study the transition state ensemble of an N=128 chain\nand search for possible reaction coordinates based on likelihood maximization.\nWe find that typical transition states consist of a crystalline nucleus with\none or more chain fragments attached to it. Furthermore, we show that the\nnumber of particles in the crystalline core is not well suited as a reaction\ncoordinate. We then present an improved reaction coordinate, which includes\ninformation from the potential energy and the overall crystallinity of the\npolymer.",
        "positive": "Theory of pressure-induced rejuvenation and strain-hardening in metallic\n  glasses: We theoretically investigate high-pressure effects on the atomic dynamics of\nmetallic glasses. The theory predicts compression-induced rejuvenation and the\nresulting strain hardening that have been recently observed in metallic\nglasses. Structural relaxation under pressure is mainly governed by local cage\ndynamics. The external pressure restricts the dynamical constraints and slows\ndown the atomic mobility. In addition, the compression induces a rejuvenated\nmetastable state (local minimum) at a higher energy in the free energy\nlandscape. Thus, compressed metallic glasses can rejuvenate and the\ncorresponding relaxation is reversible. This behavior leads to strain hardening\nin mechanical deformation experiments. Theoretical predictions agree well with\nexperiments."
    },
    {
        "anchor": "Predicting frictional ageing from bulk relaxation measurements: The coefficient of static friction between solids generally depends on the\ntime they have remained in static contact before the measurement. Such\nfrictional aging is at the origin of the difference between static and dynamic\nfriction coefficients, but has remained difficult to understand. It is usually\nattributed to a slow increase in the area of atomic contact as the interface\nchanges under pressure. This is however very difficult to quantify as surfaces\nhave roughness at all length scales, and friction is not always proportional to\nthe contact area. Here, we show that plastic flow of surface irregularities\nwithin a polymer-on-glass frictional interface exhibits identical relaxation\ndynamics as that of the bulk, allowing to predict the rate of frictional aging.",
        "positive": "Wetting in a two-dimensional capped capillary. Part I: Wetting\n  temperature and capillary prewetting: In this two-part study we investigate the phase behaviour of a fluid\nspatially confined in a semi-infinite rectangular pore formed by three\northogonal walls and connected to a reservoir maintaining constant values of\npressure and temperature in the fluid. Far from the capping wall this\nprototypical two-dimensional system reduces to a one-dimensional slit pore.\nHowever, the broken translational symmetry leads to a wetting behavior\nstrikingly different from that of a slit pore. Using a realistic model of an\natomic fluid with long-ranged Lennard-Jones fluid-fluid and fluid-substrate\ninteractions, we present for the first time detailed computations of full phase\ndiagrams of two-dimensional capped capillaries. Our analysis is based on the\nstatistical mechanics of fluids, in particular density functional theory. We\nshow the existence of capillary wetting temperature, which is a property of the\npore, and relatively to the fluid temperature determines whether capillary\ncondensation is a first-order or a continuous phase transition. We also report\nfor the first time a first-order capillary wetting transition, which can be\npreceded by a first-order capillary prewetting. A full parametric study is\nundertaken and we support our findings with exhaustive examples of density\nprofiles, adsorption and free energy isotherms, as well as full phase diagrams."
    },
    {
        "anchor": "The emergence of local wrinkling or global buckling in thin freestanding\n  bilayer films: Periodic wrinkling of a rigid capping layer on a deformable substrate\nprovides a useful method for templating surface topography for a variety of\nnovel applications. Many experiments have studied wrinkle formation during the\ncompression of a rigid film on a relatively soft pre-strained elastic\nsubstrate, and most have focused on the regime where the substrate thickness\ncan be considered semi-infinite relative to that of the film. As the relative\nthickness of the substrate is decreased, the bending stiffness of the film\ndominates, causing the bilayer to transition to either local wrinkling or a\nglobal buckling instability. In this work optical microscopy was used to study\nthe critical parameters that determine the emergence of local wrinkling or\nglobal buckling of freestanding bilayer films consisting of a thin rigid\npolymer capping layer on a pre-strained elastomeric substrate. The thickness\nratio of the film and substrate as well as the pre-strain were controlled and\nused to create a buckling phase diagram which describes the behaviour of the\nsystem as the ratio of the thickness of the substrate is decreased. A simple\nforce balance model was developed to understand the thickness and strain\ndependences of the wrinkling and buckling modes, with excellent quantitative\nagreement being obtained with experiments using only independently measured\nmaterial parameters.",
        "positive": "Complete wetting of elastically responsive substrates: We analyze theoretically complete wetting of a substrate supporting an array\nof parallel, vertical plates which can tilt elastically. The adsorbed liquid\ntilts the plates, inducing clustering, and thus modifies the substrate\ngeometry. In turn, this change in geometry alters the wetting properties of the\nsubstrate and, consequently, the adsorption of liquid. This geometry-wetting\nfeedback loop leads to stepped adsorption isotherms with each step\ncorresponding to an abrupt change in the substrate geometry. We discuss how\nthis can be used for constructing substrates with tunable wetting and\nadsorption properties."
    },
    {
        "anchor": "The unbinding transition of mixed fluid membranes: A phenomenological model for the unbinding transition of multi-component\nfluid membranes is proposed, where the unbinding transition is described using\na theory analogous to Flory-Huggins theory for polymers. The coupling between\nthe lateral phase separation of inclusion molecules and the membrane-substrate\ndistance explains the phase coexistence between two unbound phases as observed\nin recent experiments by Marx et al. [Phys. Rev. Lett. 88, 138102 (2002)].\nBellow a critical end-point temperature, we find that the unbinding transition\nbecomes first-order for multi-component membranes.",
        "positive": "Nematic-Isotropic Interfaces Under Shear: A Molecular Dynamics\n  Simulation: We present a large-scale molecular dynamics study of nematic-paranematic\ninterfaces under shear. We use a model of soft repulsive ellipsoidal particles\nwith well-known equilibrium properties, and consider interfaces which are\noriented normal to the direction of the shear gradient (common stress case).\nThe director at the interface is oriented parallel to the interface (planar). A\nfixed average shear rate is imposed with Lees-Edwards boundary conditions, and\nthe heat is dissipated with a profile-unbiased thermostat. First we study the\nproperties of the interface at one particular shear rate in detail. The local\ninterfacial profiles and the capillary wave fluctuations of the interfaces are\ncalculated and compared with those of the corresponding equilibrium interface.\nUnder shear, the interfacial width broadens and the capillary wave amplitudes\nat large wavelengths increase. The strain is distributed inhomogeneously in the\nsystem (shear banding), the local shear rate in the nematic region being\ndistinctly higher than in the paranematic region. Surprisingly, we also observe\n(symmetry breaking) flow in the {\\em vorticity} direction, with opposite\ndirection in the nematic and the paranematic state. Finally, we investigate the\nstability of the interface for other shear rates and construct a nonequilibrium\nphase diagram."
    },
    {
        "anchor": "Drying paint: from micro-scale dynamics to mechanical instabilities: Charged colloidal dispersions make up the basis of a broad range of\nindustrial and commercial products, from paints to coatings and additives in\ncosmetics. During drying, an initially liquid dispersion of such particles is\nslowly concentrated into a solid, displaying a range of mechanical\ninstabilities in response to highly variable internal pressures. Here we\nsummarise the current appreciation of this process by pairing an\nadvection-diffusion model of particle motion with a Poisson-Boltzmann cell\nmodel of inter-particle interactions, to predict the concentration gradients\naround a drying colloidal film. We then test these predictions with osmotic\ncompression experiments on colloidal silica, and small-angle x-ray scattering\nexperiments on silica dispersions drying in Hele-Shaw cells. Finally, we use\nthe details of the microscopic physics at play in these dispersions to explore\nhow two macroscopic mechanical instabilities -- shear-banding and fracture --\ncan be controlled.",
        "positive": "Slow light in degenerate Fermi gases: We investigate the effect of slow light propagating in a degenerate atomic\nFermi gas. In particular we use slow light with an orbital angular momentum. We\npresent a microscopic theory for the interplay between light and matter and\nshow how the slow light can provide an effective magnetic field acting on the\nelectrically neutral fermions, a direct analogy of the free electron gas in an\nuniform magnetic field. As an example we illustrate how the corresponding de\nHaas-van Alphen effect can be seen in a neutral gas of fermions."
    },
    {
        "anchor": "Slip-controlled thin film dynamics: In this study, we present a novel method to assess the slip length and the\nviscosity of thin films of highly viscous Newtonian liquids. We quantitatively\nanalyse dewetting fronts of low molecular weight polystyrene melts on\nOctadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin\nfilm (lubrication) model derived in the limit of large slip lengths, we can\nextract slip length and viscosity. We study polymer films with thicknesses\nbetween 50 nm and 230 nm and various temperatures above the glass transition.\nWe find slip lengths from 100 nm up to 1 micron on OTS and between 300 nm and\n10 microns on DTS covered silicon wafers. The slip length decreases with\ntemperature. The obtained values for the viscosity are consistent with\nindependent measurements.",
        "positive": "The Phase Behavior of Mixed Lipid Membranes in Presence of the Rippled\n  Phase: We propose a model describing liquid-solid phase coexistence in mixed lipid\nmembranes by including explicitly the occurrence of a rippled phase. For a\nsingle component membrane, we employ a previous model in which the membrane\nthickness is used as an order parameter. As function of temperature, this model\nproperly accounts for the phase behavior of the three possible membrane phases:\nsolid, liquid and the rippled phase. Our primary aim is to explore extensions\nof this model to binary lipid mixtures by considering the composition\ndependence of important model parameters. The obtained phase diagrams show\nvarious liquid, solid and rippled phase coexistence regions, and are in\nquantitative agreement with the experimental ones for some specific lipid\nmixtures."
    },
    {
        "anchor": "Non-additivity in many-body interactions between membrane-deforming\n  spheres increases disorder: Membrane-induced interactions have been predicted to be important for the\norganization of membrane proteins. Measurements of the interactions between two\nand three membrane deforming objects have revealed their non-additive nature.\nThey are thought to lead to complex many-body effects, however, experimental\nevidence is lacking to date. We here present an experimental method to measure\nmany-body effects in membrane-mediated interactions using colloidal spheres\nplaced between a deflated giant unilamellar vesicles and a planar substrate.\nThe thus confined colloidal particles cause a large deformation of the membrane\nwhile not being physochemically attached to it and interact through it. Two\nparticles are found to attract with a maximum force of 0.2~pN. For three\nparticles, we observe a preference for forming compact equilateral triangles\nover a linear arrangement. We use numerical energy minimization to establish\nthat the attraction stems from a reduction in the membrane-deformation energy\ncaused by the particles. Confining up to 36 particles, we find a preference for\nhexagonally close packed clusters. However, with increasing number of particles\nthe order of the confined particles decreases, while at the same time,\ndiffusivity of the particles increases. Our experiments for the first time show\nthat the non-additive nature of membrane-mediated interactions affects the\ninteractions and arrangements and ultimately leads to spherical aggregates with\nliquid-like order of potential importance for cellular processes.",
        "positive": "Thermodynamic potential of a mechanical constitutive model for two-phase\n  band flow: Starting from a simple mechanical constitutive model (the non-local diffusive\nJohnson-Segalman model; DJS model), we provide a rigorous theoretical\nexplanation as to why a unique value of the stress plateau of a highly sheared\nviscoelastic fluid is stably realized. The present analysis is based on a\nreduction theory of the degrees of freedom of the model equation in the\nneighborhood of a critical point, which leads to a time-evolution equation that\nis equivalent to those for first-order phase transitions."
    },
    {
        "anchor": "Composite states of wetting: The analytical expressions of liquid-vapor macroscopic contact angles are\nanalyzed for various simple geometries and arrangements of the substrate, in\nparticular when the latter exhibits two or more scales. It concerns the Wenzel\nstate of wetting when the substrate is completely wet, the Cassie-Baxter state\nwhen the liquid hangs over the substrate, but also intermediate states of\nwetting which are shown to be relevant and in competition with the two other\nones. Under a separation of scales hypothesis, a composition rule of contact\nangles is developed whose interest is illustrated in a close packing setup of\nrasperry-like particles.",
        "positive": "Comment on \"Elasticity Model of a Supercoiled DNA Molecule\": We perform simulations to numerically study the writhe distribution of a\nstiff polymer. We compare with analytic results of Bouchiat and Mezard (PRL 80\n1556- (1998); cond-mat/9706050)."
    },
    {
        "anchor": "Velocity autocorrelation function of fluctuating particles in\n  incompressible fluids. Toward direct numerical simulation of particle\n  dispersions: Motions of fluctuating Brownian particles in an incompressible viscous fluid\nhave been studied by coupled simulations of Brownian particles and host fluid.\nWe calculated the velocity autocorrelation functions of Brownian particles and\ncompared them with the theoretical results. Extensive discussions have been\nmade on the time scales for which our numerical model is valid.",
        "positive": "A Landau-de Gennes theory for hard colloidal rods: defects and tactoids: We construct a phenomenological Landau-de Gennes theory for hard colloidal\nrods by performing an order parameter expansion of the chemical-potential\ndependent grand potential. By fitting the coefficients to known results of\nOnsager theory, we are not only able to describe the isotropic-nematic phase\ntransition as function of density, including the well-known density jump, but\nalso the isotropic-nematic planar interface. The resulting theory is applied in\ncalculations of the isotropic core size in a radial hedgehog defect, the\ndensity dependence of linear defects of hard rods in square confinement, and\nthe formation of a nematic droplet in an isotropic background."
    },
    {
        "anchor": "Systematic incorporation of the ionic hard-core size into the\n  Debye-Huckel theory via the cumulant expansion of the Schwinger-Dyson\n  equations: The Debye-Huckel (DH) formalism of bulk electrolytes equivalent to the\ngaussian-level closure of the electrostatic Schwinger-Dyson identities without\nthe interionic hard-core (HC) coupling is extended via the cumulant treatment\nof these equations augmented by HC interactions. By confronting the monovalent\nion activity and pressure predictions of our cumulant-corrected DH (CCDH)\ntheory with hypernetted-chain results and Monte-Carlo simulations from the\nliterature, we show that this rectification extends the accuracy of the DH\nformalism from submolar into molar salt concentrations. In the case of internal\nenergies or the general case of divalent electrolytes mainly governed by charge\ncorrelations, the improved accuracy of the CCDH theory is limited to submolar\nion concentrations. Comparison with experimental data from the literature shows\nthat via the adjustment of the hydrated ion radii, the CCDH formalism can\nequally reproduce the non-uniform effect of salt increment on the ionic\nactivity coefficients up to molar concentrations. The inequality satisfied by\nthese HC sizes coincides with the cationic branch of the Hofmeister series.",
        "positive": "Persistence-Length Renormalization of Polymers in a Crowded Environment\n  of Hard Disks: The most conspicuous property of a semiflexible polymer is its persistence\nlength, defined as the decay length of tangent correlations along its contour.\nUsing an efficient stochastic growth algorithm to sample polymers embedded in a\nquenched two-dimensional hard-disk fluid, we find apparent wormlike chain\nstatistics with a renormalized persistence length. We identify a universal form\nof the disorder renormalization that suggests itself as a quantitative measure\nof molecular crowding."
    },
    {
        "anchor": "Smectic-glass transition in a liquid crystal cell with a \"dirty\"\n  substrate: We explore the smectic liquid crystal order in a cell with a \"dirty\"\nsubstrate imposing random pinnings. Within harmonic elasticity we find a subtle\nthree-dimensional surface disorder-driven transition into a pinned\nsmectic-glass, controlled by a three-dimensional Cardy-Ostlund-like fixed line,\nakin to a super-rough phase of a two-dimensional xy model. We compute the\nassociated random substrate-driven distortions of the smectic-glass state,\nidentify the characteristic length scales on the heterogeneous substrate and in\nthe bulk, and discuss a variety of experimental signatures.",
        "positive": "Shear viscosity and wall slip behavior of dense suspensions of\n  polydisperse particles: Shear viscosity and wall slip of dense suspensions of a silicone polymer\nincorporated with polydisperse particles were investigated. Three types of\nparticles with low aspect ratios were used to achieve a relatively high maximum\npacking fraction of 0.86. Such a high maximum packing fraction allowed the\npreparation of suspensions with a wide range of solid volume fractions in the\nrange of 0.62 to 0.82. The wall slip velocities of the suspensions in steady\ntorsional and capillary flows were characterized and determined to be fully\nconsistent with the mechanism of apparent slip layer formation at the wall.\nUpon wall slip corrections it was found that at shear stresses which are\nsignificantly above the yield stress the relative shear viscosity of the\nsuspensions obeys well the Krieger-Dougherty relationship that links the\nrelative shear viscosity behavior of dense suspensions solely to the ratio of\nthe volume fraction over the maximum packing fraction of solids. However, at\nlower shear stresses that are in the vicinity of the yield stresses the\nrelative shear viscosity becomes functions of both the ratio of the volume\nfraction over the maximum packing fraction and the shear stress. It is clearly\ndemonstrated that without wall slip analysis the accurate characterization of\nthe relative shear viscosity of dense suspensions is not possible."
    },
    {
        "anchor": "Influence of outer-layer finite-size effects on the rupture kinetics of\n  a thin polymer film embedded in an immiscible matrix: In capillary-driven fluid dynamics, simple departures from equilibrium offer\nthe chance to quantitatively model the resulting relaxations. These dynamics in\nturn provide insight on both practical and fundamental aspects of thin-film\nhydrodynamics. In this work, we describe a model trilayer dewetting experiment\nelucidating the effect of solid, no-slip confining boundaries on the bursting\nof a liquid film in a viscous environment. This experiment was inspired by an\nindustrial polymer processing technique, multilayer coextrusion, in which\nthousands of alternating layers are stacked atop one another. When pushed to\nthe nanoscale limit, the individual layers are found to break up on time scales\nshorter than the processing time. To gain insight on this dynamic problem, we\nhere directly observe the growth rate of holes in the middle layer of the\ntrilayer films described above, wherein the distance between the inner film and\nsolid boundary can be orders of magnitude larger than its thickness. In\notherwise identical experimental conditions, thinner films break up faster than\nthicker ones. This observation is found to agree with a scaling model that\nbalances capillary driving power and viscous dissipation with, crucially, a\nno-slip boundary condition at the solid substrate/viscous environment boundary.\nIn particular, even for the thinnest middle-layers, no finite-size effect is\nneeded to explain the data. The dynamics of hole growth is captured by a single\nmaster curve over four orders of magnitude in the dimensionless hole radius and\ntime, and is found to agree well with predictions including analytic\nexpressions for the dissipation.",
        "positive": "Near and far-field hydrodynamic interaction of two chiral squirmers: Hydrodynamic interaction strongly influences the collective behavior of the\nmicroswimmers. With this work, we study the behavior of two hydrodynamically\ninteracting self-propelled chiral swimmers in the low Reynolds number regime,\nconsidering both the near and far-field interactions. We use the chiral\nsquirmer model, a spherically shaped body with non-axisymmetric surface slip\nvelocity, which generalizes the well-known squirmer model. We calculate the\nlubrication force between the swimmers when they are very close to each other.\nBy varying the slip coefficients and the initial configuration of the swimmers,\nwe investigate their hydrodynamic behavior. In the presence of lubrication\nforce, the swimmers either repel each other or exhibit bounded motion where the\ndistance between the swimmers alters periodically. The lubrication force favors\nthe bounded motion in some parameter regime. This study is helpful to\nunderstand the collective behavior of dense suspension of ciliated\nmicroorganisms and artificial swimmers."
    },
    {
        "anchor": "Onsager's Variational Principle for the Dynamics of a Vesicle in a\n  Poiseuille Flow: We propose a systematic formulation of the migration behaviors of a vesicle\nin a Poiseuille flow based on Onsager's variational principle. Our model is\ndescribed by a combination of the phase field theory for the vesicle and the\nhydrodynamics for the flow field. The time evolution equations for the phase\nfield of the vesicle and the flow field are derived based on the Onsager's\nprinciple, where the dissipation functional is composed of viscous dissipation\nof the flow field, bending energy of the vesicle and the friction between the\nvesicle and the flow field. We performed a series of simulations on\n2-dimensional systems by changing the bending elasticity of the membrane, and\nobserved 3 types of steady states, i.e. those with bullet, snaking, and slipper\nshapes. We show that the transitions among these steady states can be\nquantitatively explained with use of the Onsager's principle, where the\ndissipation functional is dominated by the contribution from the friction\nbetween the vesicle and the flow field.",
        "positive": "Optical second harmonic generation in a ferromagnetic liquid crystal: A comparative experimental investigation of the dependence of second harmonic\ngeneration (SHG) on applied external voltage between the standard nematic\nliquid crystalline material and an analogue ferromagnetic nematic liquid\ncrystalline material was performed by using a fundamental optical beam at 800\nnm wavelength. For a ferromagnetic material, the dependence of SHG on an\napplied magnetic field was also examined. Three different polarization\ncombinations of the fundamental and the second harmonic radiation were\nanalysed. The SHG signal observed in the former material is attributed to a\ncombination of electric field-induced SHG (EFISHG) and flexoelectric\ndeformation-induced SHG, while SHG signal observed in the latter material is\nattributed solely to flexoelectric deformation-induced SHG. The obtained\ndependences of the SHG signal on the associated optical retardation show that\nin the most favourable polarization combination the two contributions generate\nabout the same effective nonlinear optical susceptibility."
    },
    {
        "anchor": "Anomalous interactions in confined charge-stabilized colloid: Charge-stabilized colloidal spheres dispersed in weak 1:1 electrolytes are\nsupposed to repel each other. Consequently, experimental evidence for anomalous\nlong-ranged like-charged attractions induced by geometric confinement inspired\na burst of activity. This has largely subsided because of nagging doubts\nregarding the experiments' reliability and interpretation. We describe a new\nclass of thermodynamically self-consistent colloidal interaction measurements\nthat confirm the appearance of pairwise attractions among colloidal spheres\nconfined by one or two bounding walls. In addition to supporting previous\nclaims for this as-yet unexplained effect, these measurements also cast new\nlight on its mechanism.",
        "positive": "Nonlinear conduction via solitons in a topological mechanical insulator: Networks of rigid bars connected by joints, termed linkages, provide a\nminimal framework to design robotic arms and mechanical metamaterials built out\nof folding components. Here, we investigate a chain-like linkage that,\naccording to linear elasticity, behaves like a topological mechanical insulator\nwhose zero-energy modes are localized at the edge. Simple experiments we\nperformed using prototypes of the chain vividly illustrate how the soft motion,\ninitially localized at the edge, can in fact propagate unobstructed all the way\nto the opposite end. We demonstrate using real prototypes, simulations and\nanalytical models that the chain is a mechanical conductor, whose carriers are\nnonlinear solitary waves, not captured within linear elasticity. Indeed, the\nlinkage prototype can be regarded as the simplest example of a topological\nmetamaterial whose protected mechanical excitations are solitons, moving domain\nwalls between distinct topological mechanical phases. More practically, we have\nbuilt a topologically protected mechanism that can perform basic tasks such as\ntransporting a mechanical state from one location to another. Our work paves\nthe way towards adopting the principle of topological robustness in the design\nof robots assembled from activated linkages as well as in the fabrication of\ncomplex molecular nanostructures."
    },
    {
        "anchor": "Polarised superlocalization in magnetic nanoparticle hyperthermia: Magnetic hyperthermia is an adjuvant therapy for cancer where injected\nmagnetic nanoparticles are used to transfer energy from the time-dependent\napplied magnetic field into the surrounding medium. Its main importance is to\nbe able to increase the temperature of the human body locally. This\nlocalization can be further increased by using a combination of static and\nalternating external magnetic fields. For example, if the static field is\ninhomogeneous and the alternating field is oscillating then the energy transfer\nand consequently, the heat generation is non-vanishing only where the gradient\nfield is zero which results in superlocalization. Our goal here is to study\ntheoretically and experimentally whether the perpendicular or parallel\ncombination of static and oscillating fields produce a better\nsuperlocalization. A considerable polarisation effect in superlocalization for\nsmall frequencies and large field strengths which are of great importance in\npractice is found.",
        "positive": "Generation of defects and disorder from deeply quenching a liquid to\n  form a solid: We show how deeply quenching a liquid to temperatures where it is linearly\nunstable and the crystal is the equilibrium phase often produces crystalline\nstructures with defects and disorder. As the solid phase advances into the\nliquid phase, the modulations in the density distribution created behind the\nadvancing solidification front do not necessarily have a wavelength that is the\nsame as the equilibrium crystal lattice spacing. This is because in a deep\nenough quench the front propagation is governed by linear processes, but the\ncrystal lattice spacing is determined by nonlinear terms. The wavelength\nmismatch can result in significant disorder behind the front that may or may\nnot persist in the latter stage dynamics. We support these observations by\npresenting results from dynamical density functional theory calculations for\nsimple one- and two-component two-dimensional systems of soft core particles."
    },
    {
        "anchor": "Application of molecular simulations: Insight into liquid bridging and\n  jetting phenomena: Molecular dynamics simulations have been performed on pure liquid water,\naqueous solutions of sodium chloride, and polymer solutions exposed to a strong\nexternal electric field with the goal to gain molecular insight into the\nstructural response to the field. Several simulation methodologies have been\nused to elucidate the molecular mechanisms of the processes leading to the\nformation of liquid bridges and jets (in the production of nanofibers). It is\nshown that in the established nanoscale structures, the molecules form a chain\nwith their dipole moments oriented parallel to the applied field throughout the\nentire sample volume. The presence of ions may disturb this structure leading\nto its ultimate disintegration into droplets; the concentration dependence of\nthe threshold field required to stabilize a liquid column has been determined.\nConformational changes of the polymer in the jetting process have also been\nobserved.",
        "positive": "Non-classical nucleation pathways in stacking-disordered crystals: The nucleation of crystals from the liquid melt is often characterized by a\ncompetition between different crystalline structures or polymorphs, and can\nresult in nuclei with heterogeneous compositions. These mixed-phase nuclei can\ndisplay nontrivial spatial arrangements, such as layered and onion-like\nstructures, whose composition varies according to the radial distance, and\nwhich so far have been explained on the basis of bulk and surface free-energy\ndifferences between the competing phases. Here we extend the generality of\nthese non-classical nucleation processes, showing that layered and onion-like\nstructures can emerge solely based on structural fluctuations even in absence\nof free-energy differences. We consider two examples of competing crystalline\nstructures, hcp and fcc forming in hard spheres, relevant for repulsive\ncolloids and dense liquids, and the cubic and hexagonal diamond forming in\nwater, relevant also for other group 14 elements such as carbon and silicon. We\nintroduce a novel structural order parameter that combined with a neural\nnetwork classification scheme allows us to study the properties of the growing\nnucleus from the early stages of nucleation. We find that small nuclei have\ndistinct size fluctuations and compositions from the nuclei that emerge from\nthe growth stage. The transition between these two regimes is characterized by\nthe formation of onion-like structures, in which the composition changes with\nthe distance from the center of the nucleus, similarly to what seen in two-step\nnucleation process."
    },
    {
        "anchor": "Experimental and numerical determination of mechanical properties of\n  polygonal wood particles and their flow analysis in silos: Responding to a lack in the literature, mechanical properties of polygonal\nwood particles are determined for use in a discrete element model (DEM) for\nflow analysis in silos, and some methods are proposed for determining such\nparameters. The parameters arrived at here have also formed part of the input\nto the SPOLY software, developed in-house to compute the DEM model with\nspheropolyhedron elements. The model is validated using a 2D physical model,\nwhere prismatic particles with polygonal cross sections are placed inside a\nsilo with variable aperture and hopper angle. Validation includes comparison of\nflow-rates computed by SPOLY, displacement profiles, and clogging thresholds\nwith experimental results. The good agreement that emerges will encourage\nfuture use of miniature triaxial tests, grain-surface profilometry, inclined\nslope tests, and numerical analysis of the intragranular stresses - toward a\ndirect construction of the contact-deformation relations required in realistic\nDEM modelling of particle flow with angular-shaped particles.",
        "positive": "Pattern Formation and Flocking for Particles Near the Jamming Transition\n  on Resource Gradient Substrates: We numerically examine a bidisperse system of active and passive particles\ncoupled to a resource substrate. The active particles deplete the resource at a\nfixed rate and move toward regions with higher resources, while all of the\nparticles interact sterically with each other. We show that at high densities,\nthis system exhibits a rich variety of pattern forming phases along with\ndirected motion or flocking as a function of the relative rates of resource\nabsorption and consumption as well as the active to passive particle ratio.\nThese include partial phase separation into rivers of active particles flowing\nthrough passive clusters, strongly phase separated states where the active\nparticles induce crystallization of the passive particles, mixed jammed states,\nand fluctuating mixed fluid phases. For higher resource recovery rates, we\ndemonstrate that the active particles can undergo motility induced phase\nseparation, while at high densities, there can be a coherent flock containing\nonly active particles or a solid mixture of active and passive particles. The\ndirected flocking motion typically shows a transient in which the flow switches\namong different directions before settling into one direction, and there is a\ncritical density below which flocking does not occur. We map out the different\nphases as function of system density, resource absorption and recovery\nrates,and the ratio of active to passive particles."
    },
    {
        "anchor": "Critical pressure asymmetry in the enclosed fluid diode: Joint physically and chemically pattered surfaces can provide efficient and\npassive manipulation of fluid flow. The ability of many of these surfaces to\nallow only unidirectional flow mean they are often referred to as fluid diodes.\nSynthetic analogues of these are enabling technologies from sustainable water\ncollection via fog harvesting, to improved wound dressings. One key fluid diode\ngeometry features a pore sandwiched between two absorbent substrates, an\nimportant design for applications which require liquid capture while preventing\nback-flow. However, the enclosed pore is particularly challenging to design as\nan effective fluid diode, due to the need for both a low Laplace pressure for\nliquid entering the pore, and a high Laplace pressure to liquid leaving. Here,\nwe calculate the Laplace pressure for fluid travelling in both directions on a\nrange of conical pore designs with a chemical gradient. We show that this\nchemical gradient is in general required to achieve the largest critical\npressure differences between incoming and outgoing liquids. Finally, we discuss\nthe optimisation strategy to maximise this critical pressure asymmetry.",
        "positive": "Topological Phases and Curvature-Driven Pattern Formation in Cholesteric\n  Shells: We study the phase behaviour of cholesteric liquid crystal shells with\ndifferent geometries. We compare the cases of tangential and no anchoring at\nthe surface, focussing on the former case, which leads to a competition between\nthe intrinsic tendency of the cholesteric to twist and the anchoring free\nenergy which suppresses it. We then characterise the topological phases arising\nclose to the isotropic-cholesteric transition. These typically consist of\nquasi-crystalline or amorphous tessellations of the surface by half-skyrmions,\nwhich are stable at lower and larger shell size respectively. For ellipsoidal\nshells, defects in the tessellation couple to local curvature, and according to\nthe shell size they either migrate to the poles or distribute uniformly on the\nsurface. For toroidal shells, the variations in the local curvature of the\nsurface stabilises heterogeneous phases where cholesteric or isotropic patterns\ncoexist with hexagonal lattices of half-skyrmions."
    },
    {
        "anchor": "Simulating the nanometric track-structure of carbon ion beams in liquid\n  water at energies relevant for hadrontherapy: The nanometric track-structure of energetic ion beams in biological media\ndetermines the direct physical damage to living cells, which is one of the main\nresponsibles of their killing or inactivation during radiotherapy treatments or\nunder cosmic radiation bombardment. In the present work, detailed\ntrack-structure Monte Carlo simulations, performed with the code SEED\n(Secondary Electron Energy Deposition), are presented for carbon ions in a wide\nenergy range in liquid water. Liquid water is the main constituent of\nbiological tissues, and carbon ions are one of the most promising projectiles\ncurrently available for ion beam cancer therapy. The simulations are based on\naccurate cross sections for the different elastic and inelastic events\ndetermining the interaction of charged particles with condensed-phase\nmaterials. The latter are derived from the ab initio calculation of the\nelectronic excitation spectrum of liquid water by means of time-dependent\ndensity functional theory (TDDFT), which is then used within the dielectric\nformalism to obtain inelastic electronic cross sections for both carbon ions\nand secondary electrons. Both the ionisation cross sections of water by carbon\nions and the excitation and ionisation cross sections for electron impact are\nobtained in very good agreement with known experimental data. The elastic\nscattering cross sections for electrons in condensed-phase water are also\nobtained from ab initio calculations by solving the Dirac-Hartree-Fock\nequation. The detailed simulations fed with reliable cross sections allow to\nassess the contribution of different physical mechanisms (electronic\nexcitation, ionisation and dissociative electron attachment -DEA-) to the\ncarbon ion-induced direct biodamage.",
        "positive": "Layer topology of smectic grain boundaries: Grain boundaries in extremely confined colloidal smectics possess a\ntopological fine structure with coexisting nematic and tetratic symmetry of the\ndirector field. An alternative way to approach the problem of smectic topology\nis via the layer structure, which is typically more accessible in experiments\non molecular liquid crystals. Here, we translate the concept of endpoint\ndefects, which appear as tetratic disclinations of quarter charge in director\ntopology, to layer topology for two-dimensional smectics. By doing so, we\nelaborate on further advantages of a topological concept evolving around the\nlayer structure rather than the director field, such as providing insight in\nthe structure of edge dislocations or virtual defects at the confining walls."
    },
    {
        "anchor": "Hierarchical Multiscale Modeling of Macromolecules and their Assemblies: Soft materials (e.g., enveloped viruses, liposomes, membranes and supercooled\nliquids) simultaneously deform or display collective behaviors, while\nundergoing atomic scale vibrations and collisions. While the multiple\nspace-time character of such systems often makes traditional molecular dynamics\nsimulation impractical, a multiscale approach has been presented that allows\nfor long-time simulation with atomic detail based on the co-evolution of\nslowly-varying order parameters (OPs) with the quasi-equilibrium probability\ndensity of atomic configurations. However, this approach breaks down when the\nstructural change is extreme, or when nearest-neighbor connectivity of atoms is\nnot maintained. In the current study, a self-consistent approach is presented\nwherein OPs and a reference structure co-evolve slowly to yield long-time\nsimulation for dynamical soft-matter phenomena such as structural transitions\nand self assembly. The development begins with the Liouville equation for N\nclassical atoms and an ansatz on the form of the associated N-atom probability\ndensity. Multiscale techniques are used to derive Langevin equations for the\ncoupled OP configurational dynamics. The net result is a set of equations for\nthe coupled stochastic dynamics of the OPs and centers of mass of the\nsubsystems that constitute a soft material body. The theory is based on an\nall-atom methodology and an interatomic force field, and therefore enables\ncalibration-free simulations of soft matter, such as macromolecular assemblies.",
        "positive": "Effect of sample height and particle elongation in the sedimentation of\n  colloidal rods: We study theoretically the effect of a gravitational field on the equilibrium\nbehaviour of a colloidal suspension of rods with different length-to-width\naspect ratios. The bulk phases of the system are described with analytical\nequations of state. The gravitational field is then incorporated via\nsedimentation path theory, which assumes a local equilibrium condition at each\naltitude of the sample. The bulk phenomenology is significantly enriched by the\npresence of the gravitational field. In a suspension of elongated rods with\nfive stable phases in bulk, the gravitational field stabilizes up to fifteen\ndifferent stacking sequences. The sample height has a non-trivial effect on the\nstable stacking sequence. New layers of distinct bulk phases appear either at\nthe top, at the bottom, or simultaneously at the top and the bottom when\nincreasing the sample height at constant colloidal concentration. We also study\nsedimentation in a mass-polydisperse suspension in which all rods have the same\nshape but different buoyant masses."
    },
    {
        "anchor": "Two-Phase Dynamics of DNA Supercoiling based on DNA Polymer Physics: DNA supercoils are generated in genome regulation processes such as\ntranscription and replication, and provide mechanical feedback to such\nprocesses. Under tension, DNA supercoil can present a coexistence state of\nplectonemic (P) and stretched (S) phases. Experiments have revealed the dynamic\nbehaviors of plectoneme, e.g. diffusion, nucleation and hopping. To represent\nthese dynamics with computational changes, we demonstrated first the fast\ndynamics on the DNA to reach torque equilibrium within the P and S phases, and\nthen identified the two-phase boundaries as collective slow variables to\ndescribe the essential dynamics. According to the time scale separation\ndemonstrated here, we accordingly developed a two-phase model on the dynamics\nof DNA supercoiling, which can capture physiologically relevant events across\ntime scales of several orders of magnitudes. In this model, we systematically\ncharacterized the slow dynamics between the two phases, and compared the\nnumerical results with that from the DNA polymer physics-based worm-like chain\nmodel. The supercoiling dynamics, including the nucleation, diffusion, and\nhopping of plectoneme, have been well represented and reproduced, using the\ntwo-phase dynamic model, at trivial computational costs. Our current\ndevelopments, therefore, can be implemented to explore multi-scale physical\nmechanisms of the DNA supercoiling-dependent physiological processes.",
        "positive": "Free energy determination of phase coexistence in model C60: A\n  comprehensive Monte Carlo study: The free energy of the solid and fluid phases of the Girifalco C60 model are\ndetermined through extensive Monte Carlo simulations. In this model the\nmolecules interact through a spherical pair potential, characterized by a\nnarrow and attractive well, adjacent to a harshly repulsive core. We have used\nthe Widom test particle method and a mapping from an Einstein crystal, in order\nto estimate the absolute free energy in the fluid and solid phases,\nrespectively; we have then determined the free energy along several isotherms,\nand the whole phase diagram, by means of standard thermodynamic integrations.\n  We highlight how the interplay between the liquid-vapor and the liquid-solid\ncoexistence conditions determines the existence of a narrow liquid pocket in\nthe phase diagram, whose stability is assessed and confirmed in agreement with\nprevious studies. In particular, the critical temperature follows closely an\nextended corresponding-states rule recently outlined by Noro and Frenkel [J.\nChem. Phys. 113:2941 (2000)].\n  We discuss the emerging \"energetic\" properties of the system, which drive the\nphase behavior in systems interacting through short-range forces [A. A. Louis,\nPhil. Trans. R. Soc. A 359:939 (2001)], in order to explain the discrepancy\nbetween the predictions of several structural indicators and the results of\nfull free energy calculations, to locate the fluid phase boundaries.\n  More generally, we aim to provide extended reference data for calculations of\nthe free energy of the C60 fullerite in the low temperature regime, as for the\ndetermination of the phase diagram of higher order fullerenes and other\nfullerene-related materials, whose description is based on the same model\nadopted in this work."
    },
    {
        "anchor": "Nonlinear curvature elasticity of nematic liquid crystals: The nonlinear elastic properties of nematic liquid crystals have acquired new\ninterest with the recent experimental observation of bulk modulated nematic\nphases which are composed by achiral molecules. We extend the\nOseen-Zocher-Frank's elastic theory for nematic liquid crystals by including\ngradients of the nematic strain tensor in the elastic deformation energy. The\ninvariants of the elastic tensor fields, up to the fourth order in the nematic\ndirector spatial derivatives, are calculated. An alternative approach that\nconsists in the extension of the linear elastic energy to higher powers of the\nnematic strain tensor, as in classical elasticity of solids, is also developed.\nThe twist-bend nematic modulated phase is investigated by both approaches and\nthe results are critically compared. The conical angle of the twist-bend phase\nis calculated as function of the elastic constants. Surface-like effects are\nconsidered. Finally, we demonstrate that a splay-bend nematic phase with small\noscillations of the nematic director around an axis is prohibited.",
        "positive": "Hydrodynamics of domain growth in nematic liquid crystals: We study the growth of aligned domains in nematic liquid crystals. Results\nare obtained solving the Beris-Edwards equations of motion using the lattice\nBoltzmann approach. Spatial anisotropy in the domain growth is shown to be a\nconsequence of the flow induced by the changing order parameter field\n(backflow). The generalization of the results to the growth of a cylindrical\ndomain, which involves the dynamics of a defect ring, is discussed."
    },
    {
        "anchor": "Dynamic Modes of Red Blood Cells in Oscillatory Shear Flow: The dynamics of red blood cells (RBCs) in oscillatory shear flow was studied\nusing differential equations of three variables: a shape parameter, the\ninclination angle $\\theta$, and phase angle $\\phi$ of the membrane rotation. In\nsteady shear flow, three types of dynamics occur depending on the shear rate\nand viscosity ratio. i) tank-treading (TT): $\\phi$ rotates while the shape and\n$\\theta$ oscillate. ii) tumbling (TB): $\\theta$ rotates while the shape and\n$\\phi$ oscillate. iii) intermediate motion: both $\\phi$ and $\\theta$ rotate\nsynchronously or intermittently. In oscillatory shear flow, RBCs show various\ndynamics based on these three motions. For a low shear frequency with zero mean\nshear rate, a limit-cycle oscillation occurs, based on the TT or TB rotation at\na high or low shear amplitude, respectively. This TT-based oscillation well\nexplains recent experiments. In the middle shear amplitude, RBCs show an\nintermittent or synchronized oscillation. As shear frequency increases, the\nvesicle oscillation becomes delayed with respect to the shear oscillation. At a\nhigh frequency, multiple limit-cycle oscillations coexist. For a high mean\nshear rate with small shear oscillation, the shape and $\\theta$ oscillate in\nthe TT motion but only one attractor exists even at high shear frequencies. The\nmeasurement of these oscillatory modes is a promising tool for quantifying the\nviscoelasticity of RBCs and synthetic capsules.",
        "positive": "Supersonic Rupture of Rubber: The rupture of rubber differs from conventional fracture. It is supersonic,\nand the speed is determined by strain levels ahead of the tip rather than total\nstrain energy as for ordinary cracks. Dissipation plays a very important role\nin allowing the propagation of ruptures, and the back edges of ruptures must\ntoughen as they contract, or the rupture is unstable. This article presents\nseveral levels of theoretical description of this phenomenon: first, a\nnumerical procedure capable of incorporating large extensions, dynamics, and\nbond rupture; second, a simple continuum model that can be solved analytically,\nand which reproduces several features of elementary shock physics; and third,\nan analytically solvable discrete model that accurately reproduces numerical\nand experimental results, and explains the scaling laws that underly this new\nfailure mode. Predictions for rupture speed compare well with experiment."
    },
    {
        "anchor": "FCC-to-BCC phase transitions in convex and concave hard particle systems: Particle shape plays an important role in the phase behavior of colloidal\nself-assembly. Recent progress in particle synthesis has made particles of\npolyhedral shapes and dimpled spherical shapes available. Here using computer\nsimulations of hard particle models, we study face-centered cubic to\nbody-centered cubic (FCC-to-BCC) phase transitions in a convex 432 polyhedral\nshape family and a concave dimpled sphere family. Particles in both families\nhave four-, three-, and two-fold rotational symmetries. Via free energy\ncalculations we find the FCC-to-BCC transitions in both families are first\norder. As a previous work reports the FCC-to-BCC phase transition is first\norder in a convex 332 family of hard polyhedra, our work provides additional\ninsight into the FCC-to-BCC transition and how the convexity or concavity of\nparticle shape affects phase transition pathways.",
        "positive": "Elasticity of colloidal gels: structural heterogeneity, foppy modes, and\n  rigidity: Rheological measurements of model colloidal gels reveal that large variations\nin the shear moduli as colloidal volume-fraction changes are not reflected by\nsimple structural parameters such as the coordination number, which remains\nalmost a constant. We resolve this apparent contradiction by conducting a\nnormal mode analysis of experimentally measured bond networks of the gels. We\nfind that structural heterogeneity of the gels, which leads to floppy modes and\na nonaffine-affine crossover as frequency increases, evolves as a function of\nthe volume fraction and is key to understand the frequency dependent\nelasticity. Without any free parameters, we achieve good qualitative agreement\nwith the measured mechanical response. Furthermore, we achieve universal\ncollapse of the shear moduli through a phenomenological spring-dashpot model\nthat accounts for the interplay between fluid viscosity, particle dissipation,\nand contributions from the affine and non-affine network deformation."
    },
    {
        "anchor": "Shear stresses of colloidal dispersions at the glass transition in\n  equilibrium and in flow: We consider a model dense colloidal dispersion at the glass transition, and\ninvestigate the connection between equilibrium stress fluctuations, seen in\nlinear shear moduli, and the shear stresses under strong flow conditions far\nfrom equilibrium, viz. flow curves for finite shear rates. To this purpose\nthermosensitive core-shell particles consisting of a polystyrene core and a\ncrosslinked poly(N-isopropylacrylamide)(PNIPAM) shell were synthesized. Data\nover an extended range in shear rates and frequencies are compared to\ntheoretical results from integrations through transients and mode coupling\napproaches. The connection between non-linear rheology and glass transition is\nclarified. While the theoretical models semi-quantitatively fit the data taken\nin fluid states and the predominant elastic response of glass, a yet\nunaccounted dissipative mechanism is identified in glassy states.",
        "positive": "Interaction energy between two separated charged spheres surrounded\n  inside and outside by electrolyte: By using the recently generalized version of Newton Shell Theorem analytical\nequations are derived to calculate the electric interaction energy between two\nseparated charged spheres surrounded outside and inside by electrolyte. This\nelectric interaction energy is calculated as a function of the electrolyte ion\nconcentration, temperature, distance between the spheres and size of the\nspheres. At the same distance between the spheres the absolute value of the\ninteraction energy decreases with increasing electrolyte ion concentration and\nincreases with increasing temperature. At zero electrolyte ion concentration\nthe derived analytical equation transforms into the Coulomb equation. Finally,\nthe analytical equation is generalized to calculate the electric interaction\nenergy of N separated charged spheres surrounded by electrolyte."
    },
    {
        "anchor": "Non-phononic density of states of two-dimensional glasses revealed by\n  random pinning: The vibrational density of states of glasses is considerably different from\nthat of crystals. In particular, there exist spatially localized vibrational\nmodes in glasses. The density of states of these non-phononic modes has been\nobserved to follow $g(\\omega) \\propto \\omega^4$, where $\\omega$ is the\nfrequency. However, in two-dimensional systems, the abundance of phonons makes\nit difficult to accurately determine this non-phononic density of states\nbecause they are strongly coupled to non-phononic modes and yield strong\nsystem-size and preparation-protocol dependencies. In this article, we utilize\nthe random pinning method to suppress phonons and disentangle their coupling\nwith non-phononic modes and successfully calculate their density of states as\n$g(\\omega) \\propto \\omega^4$. We also study their localization properties and\nconfirm that low-frequency non-phononic modes in pinned systems are truly\nlocalized without far-field contributions. We finally discuss the excess\ndensity of states over the Debye value that results from the hybridization of\nphonons and non-phononic modes.",
        "positive": "Shear banding in nematogenic fluids with oscillating orientational\n  dynamics: We investigate the occurrence of shear banding in nematogenic fluids under\nplanar Couette flow, based on mesoscopic dynamical equations for the\norientational order parameter and the shear stress. We focus on parameter\nvalues where the sheared homogeneous system exhibits regular oscillatory\norientational dynamics, whereas the equilibrium system is either isotropic\n(albeit close to the isotropic--nematic transition) or deep in its nematic\nphase. The numerical calculations are restricted to spatial variations in shear\ngradient direction. We find several new types of shear banded states\ncharacterized by regions with regular oscillatory orientational dynamics. In\nall cases shear banding is accompanied by a non--monotonicity of the flow curve\nof the homogeneous system; however, only in the case of the initially isotropic\nsystem this curve has the typical $S$--like shape. We also analyze the\ninfluence of different orientational boundary conditions and of the spatial\ncorrelation length."
    },
    {
        "anchor": "Complete Phase Diagram of DNA Unzipping: Eye, Y-fork and triple point: We study the unzipping of double stranded DNA (dsDNA) by applying a pulling\nforce at a fraction $s$ $(0 \\le s \\le 1)$ from the anchored end. From exact\nanalytical and numerical results, the complete phase diagram is presented. The\nphase diagram shows a strong ensemble dependence for various values of $s$. In\naddition, we show the existence of an ``eye'' phase and a triple point.",
        "positive": "'Boson peak' and high-frequency excitations in glassy crystals: The high-frequency excitations in glasses and supercooled liquids belong to\nthe great mysteries of the physics of condensed matter. While the fast process,\nlocated at GHz-THz, can be interpreted as encaged molecular motion, the\noccurrence of the boson peak (BP), dominating at THz frequencies, still is\ncontroversially debated. Two scenarios have evolved during recent years: the BP\nis truly collective in nature or, alternatively, it results from localized\nmodes. To help solving this controversy, we have investigated the\nhigh-frequency dielectric loss of plastic crystals (PCs), having long-range\ntranslational but no orientational order. Having in mind the well-defined\nphonon modes in PCs compared to canonical glasses, and the infrared silence of\nacoustic phonon modes, millimeter-wave and far-infrared spectroscopy should\nprovide valuable hints on the true origin of the BP. Here we show that PCs\nexhibit a BP-like feature with markedly different spectral shape compared to\ncanonical glasses, evidencing that mixing of collective phonon with local\nrelaxational modes causes the BP. In addition, we find clear evidence for a\nfast process also in PCs."
    },
    {
        "anchor": "Elasticity-Controlled Jamming Criticality in Soft Composite Solids: Soft composite solids are made of inclusions dispersed within soft matrices.\nThey are ubiquitous in nature and form the basis of many biological tissues. In\nthe field of materials science, synthetic soft composites are promising\ncandidates for building various engineering devices due to their highly\nprogrammable features. However, when the volume fraction of the inclusions\nincreases, predicting the mechanical properties of these materials poses a\nsignificant challenge for the classical theories of composite mechanics. The\ndifficulty arises from the inherently disordered, multi-scale interactions\nbetween the inclusions and the matrix. To address this challenge, we\nsystematically investigated the mechanics of densely filled soft elastomers\ncontaining stiff microspheres. We experimentally demonstrated how the\nstrain-stiffening response of the soft composites is governed by the critical\nscalings in the vicinity of a shear-jamming transition of the included\nparticles. The proposed criticality framework quantitatively connects the\noverall mechanics of a soft composite with the elasticity of the matrix and the\nparticles, and captures the diverse mechanical responses observed across a wide\nrange of material parameters. The findings uncover a novel design paradigm of\ncomposite mechanics that relies on engineering the jamming properties of the\nembedded inclusions.",
        "positive": "Wrapping an adhesive sphere with a sheet: We study the adhesion of an elastic sheet on a rigid spherical substrate.\nGauss'Theorema Egregium shows that this operation necessarily generates metric\ndistortions (i.e. stretching) as well as bending. As a result, a large variety\nof contact patterns ranging from simple disks to complex branched shapes are\nobserved as a function of both geometrical and material properties. We describe\nthese different morphologies as a function of two non-dimensional parameters\ncomparing respectively bending and stretching energies to adhesion. A complete\nconfiguration diagram is finally proposed."
    },
    {
        "anchor": "Diffusion of intrinsically disordered proteins within viscoelastic\n  membraneless droplets: In living cells, intrinsically disordered proteins (IDPs), such as FUS and\nDDX4, undergo phase separation, forming biomolecular condensates. Using\nmolecular dynamics simulations, we investigate their behavior in their\nrespective homogenous droplets. We find that the proteins exhibit transient\nsubdiffusion due to the viscoelastic nature and confinement effects in the\ndroplets. The conformation and the instantaneous diffusivity of the proteins\nsignificantly vary between the interior and the interface of the droplet,\nresulting in non-Gaussianity in the displacement distributions. This study\nhighlights key aspects of IDP behavior in biomolecular condensates.",
        "positive": "Influence of Surface Roughness on Linear Behavior and Mechanical\n  Properties of Three Cyanoacrylate-Based Adhesives Used to Bond Strain Gages: The challenge of accessing specialized adhesives designed for strain gage\napplications has been highlighted due to failures in logistic chains, requiring\nthe exploration of local alternatives. A direct simulation of strain gage\nbonding behavior with two steel plates is infeasible due to the unique\nconstruction of strain gages. Therefore, an indirect simulation method,\ncomparing local alternatives to a widely accepted adhesive, Loctite 496, was\nemployed in this study. Two potential replacements, Loctite 401 and Tekbond\n793, were tested and matched against the benchmark adhesive, with a focus on\nthe key mechanical properties: Proportional Shear Strain (PSS), Proportional\nShear Stress (PSSt), and Apparent Shear Modulus (G*). Loctite 401 exhibited the\nhighest G*, suggesting its potential use in strain gage installations if G* is\nconsidered most important. However, Tekbond 793 demonstrated superior PSS,\nMaximum Shear Stress (MSSt), and Rupture Shear Stress (RSSt) performance,\ndisplaying linear behavior even without an accelerator. Surface preparation\nconsiderations were also discussed, noting that hand abrading results in double\nthe surface roughness than using an orbital sander. The study further\nidentified two main regions concerning failure modes related to Ra, with values\nbelow 0.31 {\\mu}m causing significant variations in observed mechanical\nproperties, pointing towards factors beyond adhesive layer thickness affecting\nbond properties. Lastly, the general recommendation is the use of an\naccelerator for all tested adhesives, while the use of a surface conditioner\nand neutralizer was found to negatively impact adhesive performance."
    },
    {
        "anchor": "Inelastic collisions and anisotropic aggregation of particles in a\n  nematic collider driven by backflow: We design a nematic collider for controlled out-of-equilibrium anisotropic\naggregation of spherical colloidal particles. The nematic surrounding imparts\ndipolar interactions among the spheres. A bidirectional backflow of the nematic\nliquid crystal (NLC) in a periodic electric field forces the spheres to collide\nwith each other. The inelastic collisions are of two types, head-to-tail and\nhead-to-head. Head-to-tail collisions of dipoles result in longitudinal\naggregation while head-to-head collisions promote aggregation in the\ntransversal direction. The frequency of head-to-head collisions is set by the\nimpact parameter that allows one to control the resulting shape of aggregates,\ntheir anisotropy and fractal dimension.",
        "positive": "Vortices in Superfluid Films on Curved Surfaces: We present a systematic study of how vortices in superfluid films interact\nwith the spatially varying Gaussian curvature of the underlying substrate. The\nGaussian curvature acts as a source for a geometric potential that attracts\n(repels) vortices towards regions of negative (positive) Gaussian curvature\nindependently of the sign of their topological charge. Various experimental\ntests involving rotating superfluid films and vortex pinning are first\ndiscussed for films coating gently curved substrates that can be treated in\nperturbation theory from flatness. An estimate of the experimental regimes of\ninterest is obtained by comparing the strength of the geometrical forces to the\nvortex pinning induced by the varying thickness of the film which is in turn\ncaused by capillary effects and gravity. We then present a non-perturbative\ntechnique based on conformal mappings that leads an exact solution for the\ngeometric potential as well as the geometric correction to the interaction\nbetween vortices. The conformal mapping approach is illustrated by means of\nexplicit calculations of the geometric effects encountered in the study of some\nstrongly curved surfaces and by deriving universal bounds on their strength."
    },
    {
        "anchor": "Aerotaxis in the Closest Relatives of Animals: As the closest unicellular relatives of animals, choanoflagellates serve as\nuseful model organisms for understanding the evolution of animal\nmulticellularity. An important factor in animal evolution was the increasing\nocean oxygen levels in the Precambrian, which are thought to have influenced\nthe emergence of complex multicellular life. As a first step in addressing\nthese conditions, we study here the response of the colony-forming\nchoanoflagellate $Salpingoeca~rosetta$ to oxygen gradients. Using a\nmicrofluidic device that allows spatio-temporal variations in oxygen\nconcentrations, we report the discovery that $S.~rosetta$ display positive\naerotaxis. Analysis of the spatial population distributions provides evidence\nfor logarithmic sensing of oxygen, which enhances sensing in low oxygen\nneighborhoods. Analysis of search strategy models on the experimental colony\ntrajectories finds that choanoflagellate aerotaxis is consistent with\nstochastic navigation, the statistics of which are captured using an effective\ncontinuous version based on classical run-and-tumble chemotaxis.",
        "positive": "Incorporating Shear into Stochastic Eulerian Lagrangian Methods for\n  Rheological Studies of Complex Fluids and Soft Materials: We develop computational methods that incorporate shear into fluctuating\nhydrodynamics methods. We are motivated by the rheological responses of complex\nfluids and soft materials. Our approach is based on continuum stochastic\nhydrodynamic equations that are subject to shear boundary conditions on the\nunit periodic cell in a manner similar to the Lees-Edwards conditions of\nmolecular dynamics. Our methods take into account consistently the\nmicrostructure elastic mechanics, fluid-structure hydrodynamic coupling, and\nthermal fluctuations. For practical simulations, we develop numerical methods\nfor efficient stochastic field generation that handle the sheared generalized\nperiodic boundary conditions. We show that our numerical methods are consistent\nwith fluctuation dissipation balance and near-equilibrium statistical\nmechanics. As a demonstration in practice, we present several prototype\nrheological response studies. These include (i) shear thinning of a polymeric\nfluid, (ii) complex moduli for the oscillatory responses of a polymerized lipid\nvesicle, and (iii) aging under shear of a gel-like material."
    },
    {
        "anchor": "Indentation of ultrathin elastic films and the emergence of asymptotic\n  isometry: We study the indentation of a thin elastic film floating at the surface of a\nliquid. We focus on the onset of radial wrinkles at a threshold indentation\ndepth and the evolution of the wrinkle pattern as indentation progresses far\nbeyond this threshold. Comparison between experiments on thin polymer films and\ntheoretical calculations shows that the system very quickly reaches the Far\nfrom Threshold (FT) regime, in which wrinkles lead to the relaxation of\nazimuthal compression. Furthermore, when the indentation depth is sufficiently\nlarge that the wrinkles cover most of the film, we recognize a novel mechanical\nresponse in which the work of indentation is transmitted almost solely to the\nliquid, rather than to the floating film. We attribute this unique response to\na nontrivial isometry attained by the deformed film, and discuss the scaling\nlaws and the relevance of similar isometries to other systems in which a\nconfined sheet is subjected to weak tensile loads.",
        "positive": "Using patchy particles to prevent local rearrangements in models of\n  non-equilibrium colloidal gels: Simple models based on isotropic interparticle attractions often fail to\ncapture experimentally observed structures of colloidal gels formed through\nspinodal decomposition and subsequent arrest: the resulting gels are typically\ndenser and less branched than their experimental counterparts. Here we simulate\ngels formed from soft particles with directional attractions (\"patchy\nparticles\"), designed to inhibit lateral particle rearrangement after\naggregation. We directly compare simulated structures with experimental\ncolloidal gels made using soft attractive microgel particles, by employing a\n\"skeletonization\" method that reconstructs the 3-dimensional backbone from\nexperiment or simulation. We show that including directional attractions with\nsufficient valency leads to strongly branched structures compared to isotropic\nmodels. Furthermore, combining isotropic and directional attractions provides\nadditional control over aggregation kinetics and gel structure. Our results\nshow that the inhibition of lateral particle rearrangements strongly affects\nthe gel topology, and is an important effect to consider in computational\nmodels of colloidal gels."
    },
    {
        "anchor": "Effect of Random Fiber Network and Fracture Toughness on the Onset of\n  Cavitation in Soft Materials: Experimental and theoretical observations have agreed that the onset of\ncavitation in soft materials requires higher tensile pressure than pure water.\nThe extra tensile pressure is required since the cavitating bubble needs to\novercome the elastic energy in soft materials. In this manuscript, we have\ndeveloped two models to study and quantify the extra tensile pressure. In the\nfirst approach, we proposed a strain energy based random fiber network (RFN)\nfailure criteria in which interaction between the cavitating bubble and RFN is\nconsidered. Gelatin samples are prepared for different concentrations, and SEM\nimages are used to study the microstructural properties of the RFN. A unit-cell\nmodel is introduced to evaluate the geometrical and mechanical properties of\nthe RFN. The network strain energy formulation is then coupled with the bubble\ngrowth, and the critical condition is set as the fibers ultimate failure\nstrain. We considered soft materials as homogeneous hyper-elastic Ogden\nmaterial, and fracture-based failure criteria are proposed in the second\napproach. The critical energy release rate is considered for quantifying the\nextra tensile pressure. Both the models are then compared with the existing\ncavitation onset criteria of rubber like materials. The validation is done with\nthe experimental results of threshold tensile pressure for different gelatin\nconcentrations. We have found that due to the large distribution of the pore\nsize in the network, the nucleation pressure is similar to water. Both models\ncan moderately predict the extra tensile pressure within the intermediate range\nof gelatin concentrations. For low concentration, the network's non-affinity\nplays a significant role and must be incorporated. On the other hand, for\nhigher concentrations, the entropic deformation dominates, and strain energy\nformulation is not adequate.",
        "positive": "Blunt-end driven re-entrant ordering in quasi two-dimensional\n  dispersions of spherical DNA brushes: We investigate the effects of crowding on the conformations and assembly of\nconfined, highly charged, and thick polyelectrolyte brushes in the osmotic\nregime. Particle tracking experiments on increasingly dense suspensions of\ncolloids coated with ultra-long double stranded DNA (dsDNA) fragments reveal\nnon-monotonic particle shrinking, aggregation and re-entrant ordering. Theory\nand simulations show that shrinking is induced by the osmotic pressure exerted\nby the counterions absorbed in neighbor brushes, while aggregation and\nre-entrant ordering are the effect of a short-range attraction competing with\nthe electrostatic repulsion. Blunt-end interactions between dsDNA fragments of\nneighboring brushes are responsible for the attraction and can be tuned by\ninducing free-end backfolding through the addition of monovalent salt. Our\nresults show that base stacking is a mode parallel to hybridization to steer\ncolloidal assembly, in which attractions can be fine-tuned through salinity\nand, potentially, grafting density and temperature."
    },
    {
        "anchor": "Elastic modulus measurements of cooked Lutefisk: Lutefisk is a traditional Norwegian Christmas dish, made of dry cod soaked in\na lye solution before re-hydrated. We report measurements of the tissue\nsoftness of cooked Lutefisk. Surprisingly, we find that the elastic modulus\ndoes not seem to depend heavily on cooking time, cooking temperature and the\namount of salt, but depends instead mainly on the size of the fish fillets and\nthe period of fishing. Although the salting and cooking of the Lutefisk affects\nstrongly the visual aspect of the fish fillets, these changes are not\nmeasurable with a rheometer.",
        "positive": "Optimal coarse-grained site selection in elastic network models of\n  biomolecules: Elastic network models, simple structure-based representations of\nbiomolecules where atoms interact via short-range harmonic potentials, provide\ngreat insight into a molecule's internal dynamics and mechanical properties at\nextremely low computational cost. Their efficiency and effectiveness have made\nthem a pivotal instrument in the computer-aided study of proteins and, since a\nfew years, also of nucleic acids. In general, the coarse-grained sites, i.e.\nthose effective force centres onto which the all-atom structure is mapped, are\nconstructed based on intuitive rules: a typical choice for proteins is to\nretain only the C$_\\alpha$ atoms of each amino acid. However, a mapping\nstrategy relying only on the atom type and not the local properties of its\nembedding can be suboptimal compared to a more careful selection. Here we\npresent a strategy in which the subset of atoms, each of which is mapped onto a\nunique coarse-grained site of the model, is selected in a stochastic search\naimed at optimising a cost function. The latter is taken to be a simple measure\nof the consistency between the harmonic approximation of an elastic network\nmodel and the harmonic model obtained through exact integration of the\ndiscarded degrees of freedom. The method is applied to two representatives of\nstructurally very different types of biomolecules: the protein Adenylate kinase\nand the RNA molecule adenine riboswitch. Our analysis quantifies the\nsubstantial impact that an algorithm-driven selection of coarse-grained sites\ncan have on a model's properties."
    },
    {
        "anchor": "Construction and calibration of a goniometer to measure contact angles\n  and calculate the surface free energy in solids with uncertainty analysis: Here, we present the construction and calibration of a low-cost goniometer to\nmeasure contact angles by the sessile drop method. Besides, we propose a simple\nand fast method to calculate the uncertainty in the determination of the\nsurface free energy (SFE) and its polar and dispersive components through the\nOwens-Wendt model and tested it by using two testing liquids. The goniometer\nperformance and the SFE uncertainty were determined on two polymers:\npolytetrafluorethylene (PTFE) and polyoxymethylene (POM), by using water and\nmethylene iodide. The values of contact angle measured were used to calculate\nthe SFE and its components with their errors. The SFE values obtained for PTFE\nwere 17.57-17.91 mJ/m^2, with a relative error lower than 5.5 %, whereas those\nfor POM were 42.80-43.23 mJ/m^2, with a relative error lower than 4.3%. Both\nthe SFE values and the errors were in the range of those previously reported.\nBased on the mathematical analysis of the uncertainty propagation in the\ndetermination of SFE, we concluded that the uncertainty is minimized when the\ntesting liquids are an apolar liquid and water.",
        "positive": "Homogeneous Free Cooling State in Binary Granular Fluids of Inelastic\n  Rough Hard Spheres: In a recent paper [A. Santos, G. M. Kremer, and V. Garz\\'o, \\emph{Prog.\nTheor. Phys. Suppl.} \\textbf{184}, 31-48 (2010)] the collisional energy\nproduction rates associated with the translational and rotational granular\ntemperatures in a granular fluid mixture of inelastic rough hard spheres have\nbeen derived. In the present paper the energy production rates are explicitly\ndecomposed into equipartition rates (tending to make all the temperatures\nequal) plus genuine cooling rates (reflecting the collisional dissipation of\nenergy). Next the homogeneous free cooling state of a binary mixture is\nanalyzed, with special emphasis on the quasi-smooth limit. A previously\nreported singular behavior (according to which a vanishingly small amount of\nroughness has a finite effect, with respect to the perfectly smooth case, on\nthe asymptotic long-time translational/translational temperature ratio) is\nfurther elaborated. Moreover, the study of the time evolution of the\ntemperature ratios shows that this dramatic influence of roughness already\nappears in the transient regime for times comparable to the relaxation time of\nperfectly smooth spheres."
    },
    {
        "anchor": "Heterogeneous diffusion in a reversible gel: We introduce a microscopically realistic model of a physical gel and use\ncomputer simulations to study its static and dynamic properties at thermal\nequilibrium. The phase diagram comprises a sol phase, a coexistence region\nending at a critical point, a gelation line determined by geometric\npercolation, and an equilibrium gel phase unrelated to phase separation. The\nglobal structure of the gel is homogeneous, but the stress is supported by a\nfractal network. The gel dynamics is highly heterogeneous and we propose a\ntheoretical model to quantitatively describe dynamic heterogeneity in gels. We\nelucidate several differences between the dynamics of gels and that of\nglass-formers.",
        "positive": "Connection between Adam-Gibbs Theory and Spatially Heterogeneous\n  Dynamics: We investigate the spatially heterogeneous dynamics in the SPC/E model of\nwater by using molecular dynamics simulations. We relate the average mass $n^*$\nof mobile particle clusters to the diffusion constant and the configurational\nentropy. Hence, $n^*$ can be interpreted as the mass of the ``cooperatively\nrearranging regions'' that form the basis of the\n  Adam-Gibbs theory of the dynamics of supercooled liquids. Finally, we examine\nthe time and temperature dependence of these transient clusters."
    },
    {
        "anchor": "Compaction and mobility in randomly agitated granular assemblies: We study the compaction and mobility properties of a dense granular material\nunder weak random vibration. By putting in direct contact millimetric glass\nbeads with piezoelectric transducers we manage to inject energy to the system\nin a disordered manner with accelerations much smaller than gravity, resulting\nin a slow compaction dynamics and no convection. We characterize the mobility\ninside the medium by pulling through it an intruder grain at constant velocity.\nWe present an extensive study of the relation between drag force and velocity\nfor different vibration conditions and sizes of the intruder.",
        "positive": "Vortex formation and dynamics of defects in shells of active nematics: We present a hydrodynamic model for a thin spherical shell of active nematic\nliquid crystal with an arbitrary configuration of defects. The active flows\ngenerated by defects in the director lead to the formation of stable vortices,\nanalogous to those seen in confined systems in flat geometries, which generate\nan effective dynamics for four +1/2 defects that reproduces the tetrahedral to\nplanar oscillations observed in experiments. As the activity is increased and\nthe vortices become stronger, the defects are drawn more tightly into pairs,\nrotating about antipodal points. We extend this situation to also describe the\ndynamics of other configurations of defects. For example, two +1 defects are\nfound to attract or repel according to the local geometric character of the\ndirector field around them, while additional pairs of opposite charge defects\ncan give rise to flow states containing more than two vortices. Finally, we\ndescribe the generic relationship between defects in the orientation and\nsingular points of the flow, and suggest implications for the three-dimensional\nnature of the flow and deformation in the shape of the shell."
    },
    {
        "anchor": "Initial stresses in elastic solids: Constitutive laws and\n  acoustoelasticity: On the basis of the nonlinear theory of elasticity, the general constitutive\nequation for an isotropic hyperelastic solid in the presence of initial stress\nis derived. This derivation involves invariants that couple the deformation\nwith the initial stress and in general, for a compressible material, it\nrequires 10 invariants, reducing to 9 for an incompressible material.\nExpressions for the Cauchy and nominal stress tensors in a finitely deformed\nconfiguration are given along with the elasticity tensor and its specialization\nto the initially stressed undeformed configuration. The equations governing\ninfinitesimal motions superimposed on a finite deformation are then used to\nstudy the combined effects of initial stress and finite deformation on the\npropagation of homogeneous plane waves in a homogeneously deformed and\ninitially stressed solid of infinite extent. This general framework allows for\nvarious different specializations, which make contact with earlier works. In\nparticular, connections with results derived within Biot's classical theory are\nhighlighted. The general results are also specialized to the case of a small\ninitial stress and a small pre-deformation, i.e. to the evaluation of the\nacoustoelastic effect. Here the formulas derived for the wave speeds cover the\ncase of a second-order elastic solid without initial stress and subject to a\nuniaxial tension [Hughes and Kelly, Phys. Rev. 92 (1953) 1145] and are\nconsistent with results for an undeformed solid subject to a residual stress\n[Man and Lu, J. Elasticity 17 (1987) 159]. These formulas provide a basis for\nacoustic evaluation of the second- and third-order elasticity constants and of\nthe residual stresses. The results are further illustrated in respect of a\nprototype model of nonlinear elasticity with initial stress, allowing for both\nfinite deformation and nonlinear dependence on the initial stress.",
        "positive": "Dynamics in a one-dimensional ferrogel model: relaxation, pairing,\n  shock-wave propagation: Ferrogels are smart soft materials, consisting of a polymeric network and\nembedded magnetic particles. Novel phenomena, such as the variation of the\noverall mechanical properties by external magnetic fields, emerge consequently.\nHowever, the dynamic behavior of ferrogels remains largely unveiled. In this\npaper, we consider a one-dimensional chain consisting of magnetic dipoles and\nelastic springs between them as a simple model for ferrogels. The model is\nevaluated by corresponding simulations. To probe the dynamics theoretically, we\ninvestigate a continuum limit of the energy governing the system and the\ncorresponding equation of motion. We provide general classification scenarios\nfor the dynamics, elucidating the touching/detachment dynamics of the magnetic\nparticles along the chain. In particular, it is verified in certain cases that\nthe long-time relaxation corresponds to solutions of shock-wave propagation,\nwhile formations of particle pairs underlie the initial stage of the dynamics.\nWe expect that these results will provide insight into the understanding of the\ndynamics of more realistic models with randomness in parameters and\ntime-dependent magnetic fields."
    },
    {
        "anchor": "How charges separate when surfaces are dewetted: Charge separation at moving three-phase contact lines is observed in nature\nas well as technological processes. Despite the growing number of experimental\ninvestigations in recent years, the physical mechanism behind the charging\nremains obscure. Here we identify the origin of charge separation as the\ndewetting of the bound surface charge within the electric double layer by the\nreceding contact line. This charge depends strongly on the local electric\ndouble layer structure close to the contact line, which is affected by the\ngas-liquid interface and the internal flow of the liquid. We summarize the\ncharge separation mechanism in an analytical model that captures parametric\ndependencies in agreement with our experiments and numerical simulations.\nCharge separation increases with increasing contact angle and decreases with\nincreasing dewetting velocity. Our findings reveal the universal mechanism of\ncharge separation at receding contact lines, relevant to many dynamic wetting\nscenarios, and provide a theoretical foundation for both fundamental questions,\nlike contact angle hysteresis, and practical applications.",
        "positive": "Semidilute Principle for Gels: Polymer gels such as jellies and soft contact lenses are soft solids\nconsisting of three-dimensional polymer networks swollen with a large amount of\nsolvent. For approximately 80 years, the swelling of polymer gels has been\ndescribed using the Flory--Huggins mean-field theory. However, this theory is\nproblematic when applied to polymer gels with large solvent contents owing to\nthe significant fluctuations in polymer concentration. In this study, we\nexperimentally demonstrate the superiority of the semidilute scaling law over\nthe mean-field theory for predicting the swelling of polymer gels. Using the\nsemidilute scaling law, we experimentally determine the universal critical\nexponent $\\nu$ of the self-avoiding walk via swelling experiments on polymer\ngels. The experimentally obtained value $\\nu\\simeq 0.589$ is consistent with\nthe previously reported value of $\\nu\\simeq 0.588$, which was obtained by\nprecise numerical calculations. Furthermore, we theoretically derive and\nexperimentally demonstrate a scaling law that governs the equilibrium\nconcentrations. This scaling law contradicts the predictions made by de Gennes'\n$c^{*}$ theorem. A major deficiency of the $c^*$ theorem is that the network\nelasticity, which depends on the as-prepared state, is neglected. These\nfindings reveal that the semidilute scaling law is a fundamental principle for\naccurately predicting and controlling the equilibrium swelling of polymer gels."
    },
    {
        "anchor": "Continuum simulation of the discharge of the granular silo: a validation\n  test for the mu(I)-visco-plastic flow law: Using both a continuum Navier-Stokes solver, with the mu(I)-flow-law\nimplemented to model the viscous behavior, and the discrete Contact Dynamics\nalgorithm, the discharge of granular silos is simulated in two dimensions from\nthe early stages of the discharge until complete release of the material. In\nboth cases, the Beverloo scaling is recovered. We first do not attempt\nquantitative comparison, but focus on the qualitative behavior of velocity and\npressure at different locations in the flow. A good agreement is obtained in\nthe regions of rapid flows, while areas of slow creep are not entirely captured\nby the continuum model. The pressure field shows a general good agreement. The\nevolution of the free surface implies differences, however, the bulk\ndeformation is essentially identical in both approaches. The influence of the\nparameters of the mu(I)-flow-law is systematically investigated, showing the\nimportance of the dependence on the inertial number I to achieve quantitative\nagreement between continuum and discrete discharge. The general ability of the\ncontinuum model to reproduce qualitatively the granular behavior is found to be\nvery encouraging.",
        "positive": "Resolving Dispersion and Induction Components for Polarisable Molecular\n  Simulations of Ionic Liquids: One important development in interaction potential models, or atomistic force\nfields, for molecular simulation is the inclusion of explicit polarisation,\nwhich represents the induction effects of charged or polar molecules on\npolarisable electron clouds. Polarisation can be included through fluctuating\ncharges, induced multipoles or Drude dipoles. This work uses Drude dipoles and\nis focused on room-temperature ionic liquids, for which fixed-charge models\npredict too slow dynamics. The aim of this study is to devise a strategy to\nadapt existing non-polarisable force fields upon addition of polarisation,\nbecause induction was already contained to an extent, implicitly, due to\nparametrisation against empirical data. Therefore, a fraction of the van der\nWaals interaction energy should be subtracted so that the Lennard-Jones terms\nonly account for dispersion and the Drude dipoles for induction.\nSymmetry-adapted perturbation theory (SAPT) is used to resolve the dispersion\nand induction terms in dimers and to calculate scaling factors to reduce the\nLennard-Jones terms from the non-polarisable model. Simply adding Drude dipoles\nto an existing fixed-charge model already improves the prediction of transport\nproperties, increasing diffusion coefficients and lowering the viscosity.\nScaling down the Lennard-Jones terms leads to still faster dynamics and to\ndensities that match experiment extremely well. The concept developed here\nimproves the prediction of density and transport properties and can be adapted\nto other models and systems. The inclusion of polarisation and the down-scaling\nof Lennard-Jones terms affects onyl slightly the ordering of the first shell of\ncounterions, leading to small decreases in coordination numbers. The effect of\npolarisation is major beyond first neighbours, weakening spatial correlations,\na structural effect related to the faster dynamics of polarisable models."
    },
    {
        "anchor": "Shapes enhancing the propulsion of multiflagellated helical\n  microswimmers: In this paper we are interested in optimizing the shape of multi-flagellated\nhelical microswimmers. Mimicking the propagation of helical waves along the\nflagella, they self-propel by rotating their tails. The swimmer's dynamics is\ncomputed using the Boundary Element Method, implemented in the open source\nMatlab library $Gypsilab$. We exploit a Bayesian optimization algorithm to\nmaximize the swimmer's speeds through their shape optimization. Our results\nshow that the optimal tail shapes are helices with large wavelength, such that\nthe shape periodicity is disregarded. Moreover, the best propulsion speed is\nachieved for elongated heads when the swimmer has one or two flagella.\nSurprisingly, a round head is obtained when more flagella are considered. Our\nresults indicate that the position and number of flagella modify the propulsion\npattern and play a significant role in the optimal design of the head. It\nappears that Bayesian optimization is a promising method for performance\nimprovement in microswimming.",
        "positive": "Liquid crystal-enabled electroosmosis through spatial charge separation\n  in distorted regions as a novel mechanism of electrokinetics: Electrically-controlled dynamics of fluids and particles at microscales is a\nfascinating area of research with applications ranging from microfluidics and\nsensing to sorting of biomolecules. The driving mechanisms are electric forces\nacting on spatially separated charges in an isotropic medium such as water.\nHere we demonstrate that anisotropic conductivity of liquid crystals enables\nnew mechanism of highly efficient electro-osmosis rooted in space charging of\nregions with distorted orientation. The electric field acts on these\ndistortion-separated charges to induce liquid crystal-enabled electro-osmosis\n(LCEO). LCEO velocities grow with the square of the field, which allows one to\nuse an AC field to drive steady flows and to avoid electrode damage. Ionic\ncurrents in liquid crystals that have been traditionally considered as an\nundesirable feature in displays, offer a broad platform for versatile\napplications such as liquid crystal enabled electrokinetics, micropumping and\nmixing."
    },
    {
        "anchor": "Bose-Einstein condensation dynamics in three dimensions by the\n  pseudospectral and finite-difference methods: We suggest a pseudospectral method for solving the three-dimensional\ntime-dependent Gross-Pitaevskii (GP) equation and use it to study the resonance\ndynamics of a trapped Bose-Einstein condensate induced by a periodic variation\nin the atomic scattering length. When the frequency of oscillation of the\nscattering length is an even multiple of one of the trapping frequencies along\nthe $x$, $y$, or $z$ direction, the corresponding size of the condensate\nexecutes resonant oscillation. Using the concept of the differentiation matrix,\nthe partial-differential GP equation is reduced to a set of coupled ordinary\ndifferential equations which is solved by a fourth-order adaptive step-size\ncontrol Runge-Kutta method. The pseudospectral method is contrasted with the\nfinite-difference method for the same problem, where the time evolution is\nperformed by the Crank-Nicholson algorithm. The latter method is illustrated to\nbe more suitable for a three-dimensional standing-wave optical-lattice trapping\npotential.",
        "positive": "Connecting short and long time dynamics in hard-sphere-like colloidal\n  glasses: Glass-forming materials are characterized by an intermittent motion at the\nmicroscopic scale. Particles spend most of their time rattling within the cages\nformed by their neighbors, and seldom jump to a different cage. In molecular\nglass formers the temperature dependence of the jump features, such as the\naverage caging time and jump length, characterizes the relaxation processes and\nallows for a short-time prediction of the diffusivity. Here we experimentally\ninvestigate the cage-jump motion of a two-dimensional hard-sphere-like\ncolloidal suspension, where the volume fraction is the relevant parameter\ncontrolling the slowing down of the dynamics. We characterize the volume\nfraction dependence of the cage-jump features and show that, as in molecular\nsystems, they allow for a short time prediction of the diffusivity."
    },
    {
        "anchor": "Phase separating binary fluids under oscillatory shear: We apply lattice Boltzmann methods to study the segregation of binary fluid\nmixtures under oscillatory shear flow in two dimensions. The algorithm allows\nto simulate systems whose dynamics is described by the Navier-Stokes and the\nconvection-diffusion equations. The interplay between several time scales\nproduces a rich and complex phenomenology. We investigate the effects of\ndifferent oscillation frequencies and viscosities on the morphology of the\nphase separating domains. We find that at high frequencies the evolution is\nalmost isotropic with growth exponents 2/3 and 1/3 in the inertial (low\nviscosity) and diffusive (high viscosity) regimes, respectively. When the\nperiod of the applied shear flow becomes of the same order of the relaxation\ntime $T_R$ of the shear velocity profile, anisotropic effects are clearly\nobservable. In correspondence with non-linear patterns for the velocity\nprofiles, we find configurations where lamellar order close to the walls\ncoexists with isotropic domains in the middle of the system. For particular\nvalues of frequency and viscosity it can also happen that the convective\neffects induced by the oscillations cause an interruption or a slowing of the\nsegregation process, as found in some experiments. Finally, at very low\nfrequencies, the morphology of domains is characterized by lamellar order\neverywhere in the system resembling what happens in the case with steady shear.",
        "positive": "Versatile approach to access the low temperature thermodynamics of\n  lattice polymers and proteins: We show that Wang-Landau sampling, combined with suitable Monte Carlo trial\nmoves, provides a powerful method for both the ground state search and the\ndetermination of the density of states for the hydrophobic-polar (HP) protein\nmodel and the interacting self-avoiding walk (ISAW) model for homopolymers. We\nobtained accurate estimates of thermodynamic quantities for HP sequences with\n$>100$ monomers and for ISAWs up to $>500$ monomers. Our procedure possesses an\nintrinsic simplicity and overcomes the limitations inherent in more tailored\napproaches making it interesting for a broad range of protein and polymer\nmodels."
    },
    {
        "anchor": "The rheology of concentrated suspensions of arbitrarily-shaped particles: We propose an improved effective-medium theory to obtain the concentration\ndependence of the viscosity of particle suspensions at arbitrary volume\nfractions. Our methodology can be applied, in principle, to any particle shape\nas long as the intrinsic viscosity is known in the dilute limit and the\nparticles are not too elongated. The procedure allows to construct a\ncontinuum-medium model in which correlations between the particles are\nintroduced through an effective volume fraction. We have tested the procedure\nusing spheres, ellipsoids, cylinders, dumbells, and other complex shapes. In\nthe case of hard spherical particles, our expression improves considerably\nprevious models like the widely used Krieger-Dougherty relation. The final\nexpressions obtained for the viscosity scale with the effective volume fraction\nand show remarkable agreement with experiments and numerical simulations at a\nlarge variety of situations.",
        "positive": "Statistical Mechanics of Vacancy and Interstitial Strings in Hexagonal\n  Columnar Crystals: Columnar crystals contain defects in the form of vacancy/interstitial loops\nor strings of vacancies and interstitials bounded by column ``heads'' and\n``tails''. These defect strings are oriented by the columnar lattice and can\nchange size and shape by movement of the ends and forming kinks along the\nlength. Hence an analysis in terms of directed living polymers is appropriate\nto study their size and shape distribution, volume fraction, etc. If the\nentropy of transverse fluctuations overcomes the string line tension in the\ncrystalline phase, a string proliferation transition occurs, leading to a\nsupersolid phase. We estimate the wandering entropy and examine the behaviour\nin the transition regime. We also calculate numerically the line tension of\nvarious species of vacancies and interstitials in a triangular lattice for\npower-law potentials as well as for a modified Bessel function interaction\nbetween columns as occurs in the case of flux lines in type-II superconductors\nor long polyelectrolytes in an ionic solution. We find that the centered\ninterstitial is the lowest energy defect for a very wide range of interactions;\nthe symmetric vacancy is preferred only for extremely short interaction ranges."
    },
    {
        "anchor": "Swarming, swirling and stasis in sequestered bristle-bots: The collective ability of organisms to move coherently in space and time is\nubiquitous in any group of autonomous agents that can move and sense each other\nand the environment. Here we investigate the origin of collective motion and\nits loss using macroscopic self-propelled Bristle-Bots, simple automata made\nfrom a toothbrush and powered by an onboard cell phone vibrator-motor, that can\nsense each other through shape-dependent local interactions, and can also sense\nthe environment non-locally via the effects of confinement and substrate\ntopography. We show that when Bristle-Bots are confined to a limited arena with\na soft boundary, increasing the density drives a transition from a disordered\nand uncoordinated motion to organized collective motion either as a swirling\ncluster or a collective dynamical stasis. This transition is regulated by a\nsingle parameter, the relative magnitude of spinning and walking in a single\nautomaton. We explain this using quantitative experiments and simulations that\nemphasize the role of the agent shape, environment, and confinement via\nboundaries. Our study shows how the behavioral repertoire of these physically\ninteracting automatons controlled by one parameter translates into the\nmechanical intelligence of swarms.",
        "positive": "Probing the Local Response of Glass-forming Liquids by Laser Excitations: The glass is a disordered solid that processes distinct dynamical and elastic\nproperties compared with crystal. How heterogeneous glassy materials can be and\nto what extent dynamics is encoded with structure and elasticity are\nlong-standing puzzles in glass science. In this experiment, we probed the\nresponses of binary colloidal glasses towards the excitations induced by highly\nfocused laser pulses. We observed very similar excitation patterns when the\nlaser was repeated in the linear region; directly proving that the dynamical\nheterogeneity is strongly encoded with structure. In the non-linear region, we\nidentified a non-monotonic dynamical length scale as a function of area\nfraction, resulting from the non-monotonic coupling of momentum transfer in\nradial and orthogonal directions. Surprisingly, the excitation size and radius\nof gyration conformed to a universal scaling relation that covered both linear\nand non-linear regions. Our experiments offered a new strategy of actively\nprobing the response of glassy materials on the microscopic level."
    },
    {
        "anchor": "Entropic Stabilization of Tunable Planar Modulated Superstructures: Self-assembling novel ordered structures with nanoparticles has recently\nreceived much attention. Here we use computer simulations to study a\ntwo-dimensional model system characterized by a simple isotropic interaction\nthat could be realized with building blocks on the nanoscale. We find that the\nparticles arrange themselves into hexagonal superstructures of twin boundaries\nwhose superlattice vector can be tuned reversibly by changing the temperature.\nThermodynamic stability is confirmed by calculating the free energy with a\ncombination of thermodynamic integration and the Frenkel-Ladd method. Different\ncontributions to the free energy difference are discussed.",
        "positive": "Electrochemical reaction in single layer MoS2: nanopores opened atom by\n  atom: Ultrathin nanopore membranes based on 2D materials have demonstrated ultimate\nresolution toward DNA sequencing. Among them, molybdenum disulphide (MoS2)\nshows long-term stability as well as superior sensitivity enabling high\nthroughput performance. The traditional method of fabricating nanopores with\nnanometer precision is based on the use of focused electron beams in\ntransmission electron microscope (TEM). This nanopore fabrication process is\ntime-consuming, expensive, not scalable and hard to control below 1 nm. Here,\nwe exploited the electrochemical activity of MoS2 and developed a convenient\nand scalable method to controllably make nanopores in single-layer MoS2 with\nsub-nanometer precision using electrochemical reaction (ECR). The\nelectrochemical reaction on the surface of single-layer MoS2 is initiated at\nthe location of defects or single atom vacancy, followed by the successive\nremovals of individual atoms or unit cells from single-layer MoS2 lattice and\nfinally formation of a nanopore. Step-like features in the ionic current\nthrough the growing nanopore provide direct feedback on the nanopore size\ninferred from a widely used conductance vs. pore size model. Furthermore, DNA\ntranslocations can be detected in-situ when as-fabricated MoS2 nanopores are\nused. The atomic resolution and accessibility of this approach paves the way\nfor mass production of nanopores in 2D membranes for potential solid-state\nnanopore sequencing."
    },
    {
        "anchor": "From discrete to continuous description of spherical surface charge\n  distributions: The importance of electrostatic interactions in soft matter and biological\nsystems can often be traced to non-uniform charge effects, which are commonly\ndescribed using a multipole expansion of the corresponding charge distribution.\nThe standard approach when extracting the charge distribution of a given system\nis to treat the constituent charges as points. This can, however, lead to an\noverestimation of multipole moments of high order, such as dipole, quadrupole,\nand higher moments. Focusing on distributions of charges located on a spherical\nsurface -- characteristic of numerous biological macromolecules, such as\nglobular proteins and viral capsids, as well as of inverse patchy colloids --\nwe develop a novel way of representing spherical surface charge distributions\nbased on the von Mises-Fisher distribution. This approach takes into account\nthe finite spatial extension of individual charges, and leads to a simple yet\npowerful way of describing surface charge distributions and their multipole\nexpansions. In this manner, we analyze charge distributions and the derived\nmultipole moments of a number of different spherical configurations of\nidentical charges with various degrees of symmetry. We show how the number of\ncharges, their size, and the geometry of their configuration influence the\nbehavior and relative importance of multipole magnitudes of different order.\nImportantly, we clearly demonstrate how neglecting the effect of charge size\nleads to an overestimation of high-order multipoles. The results of our work\ncan be applied to construct analytical models of electrostatic interactions and\nmultipole expansion of charged particles in diverse soft matter and biological\nsystems.",
        "positive": "Rapid granular flows on a rough incline: phase diagram, gas transition,\n  and effects of air drag: We report experiments on the overall phase diagram of granular flows on an\nincline with emphasis on high inclination angles where the mean layer velocity\napproaches the terminal velocity of a single particle free falling in air. The\ngranular flow was characterized by measurements of the surface velocity, the\naverage layer height, and the mean density of the layer as functions of the\nhopper opening, the plane inclination angle and the downstream distance x of\nthe flow. At high inclination angles the flow does not reach an x-invariant\nsteady state over the length of the inclined plane. For low volume flow rates,\na transition was detected between dense and very dilute (gas) flow regimes. We\nshow using a vacuum flow channel that air did not qualitatively change the\nphase diagram and did not quantitatively modify mean flow velocities of the\ngranular layer except for small changes in the very dilute gas-like phase."
    },
    {
        "anchor": "Depletion Forces in Athermally Sheared Mixtures of Frictionless Disks\n  and Rods in Two Dimensions: We carry out numerical simulations to study the behavior of an athermal\nmixture of frictionless circular disks and elongated rods in two dimensions,\nunder three different types of global linear deformation at a finite strain\nrate: (i) simple shearing, (ii) pure shearing, and (iii) isotropic compression.\nWe find that the fluctuations induced by such deformations lead to depletion\nforces that cause rods to group in parallel oriented clusters for the cases of\nsimple and pure shear, but not for isotropic compression. For simple shearing,\nwe find that as the fraction of rods increases, this clustering increases,\nleading to an increase in the average rate of rotation of the rods, and a\ndecrease in the magnitude of their nematic ordering.",
        "positive": "Comparison of all atom and united atom models for thermal transport\n  calculations of amorphous polyethylene: Polymer simulations routinely employ models with different molecular\nresolutions. United atom (UA) models are one such example, where groups of\ncertain atoms in a molecule are clustered into superatoms. Although their\ncomputational simplicity makes them particularly attractive for studying a wide\nrange of polymer properties, the missing degrees of freedom in UA models can\nimpact certain properties that are intimately linked to localized vibrations,\nsuch as the heat capacity and the thermal transport coefficient $\\kappa$. In\ncontrast, the numerically exhausting all atom (AA) models produce results that\nbetter match experimental data. In this work, we systematically investigate and\ncompare $\\kappa$ obtained from an AA and a UA models for an amorphous\npolyethylene system. The results indicate that the UA description may not be a\nsuitable model for evaluating thermal transport, since it underestimates\n$\\kappa$ in comparison to an AA description and the experimental value. The\ncoarse-graining leads to the softer interactions and its presence is\nhighlighted in a weaker mechanical response from the UA model, thus also\nunderestimates $\\kappa$. We further consolidate our findings by extracting the\nbonded and the nonbonded contributions to $\\kappa$ within the framework of the\nsingle chain energy transfer model."
    },
    {
        "anchor": "Nonequilibrium free energy during polymer chain growth: During fast diffusion-influenced polymerization, nonequilibrium behavior of\nthe polymer chains and the surrounding reactive monomers has been reported\nrecently. Based on the laws of thermodynamics, the emerging nonequilibrium\nstructures should be characterisable by some \"extra free energy\" (excess over\nthe equilibrium Helmholtz free energy). Here, we study the nonequilibrium\nthermodynamics of chain-growth polymerization of ideal chains in a dispersion\nof free reactive monomers, using off-lattice, reactive Brownian Dynamics (R-BD)\ncomputer simulations in conjunction with approximative statistical mechanics\nand relative entropy (Gibbs-Shannon and Kullback-Leibler) concepts. In case of\nfast growing polymers, we indeed report increased nonequilibrium free energies\nof several kBT compared to equilibrium and near-equilibrium, slowly growing\nchains. Interestingly, the extra free energy is a non-monotonic function of the\ndegree of polymerization and thus also of time. Our decomposition of the\nthermodynamic contributions shows that the initial dominant extra free energy\nis stored in the nonequilibrium inhomogeneous density profiles of the free\nmonomer gas (showing density depletion and wakes) in the vicinity of the active\ncenter at the propagating polymer end. At later stages of the polymerization\nprocess, we report significant extra contributions stored in the nonequilibrium\npolymer conformations. Finally, our study implies a nontrivial relaxation\nkinetics and restoring of the extra free energy during the equilibration\nprocess after polymerization.",
        "positive": "Elasto-plastic description of brittle failure in amorphous materials: The response of amorphous materials to an applied strain can be continuous,\nor instead display a macroscopic stress drop when a shear band nucleates. Such\ndiscontinuous response can be observed if the initial configuration is very\nstable. We study theoretically how such brittleness emerges in athermal,\nquasi-statically driven, materials as their initial stability is increased. We\nshow that this emergence is well reproduced by elasto-plastic models and is\npredicted by a mean field approximation, where it corresponds to a continuous\ntransition. In mean field, failure can be forecasted from the avalanche\nstatistics. We show that this is not the case for very brittle materials in\nfinite dimensions due to rare weak regions where a shear band nucleates. Their\ncritical radius is predicted to follow $a_c\\sim (\\Sigma-\\Sigma_b)^{-2}$, where\n$\\Sigma$ is the stress and $\\Sigma_b$ the stress a shear band can carry."
    },
    {
        "anchor": "Nonlinear viscoelastic dynamics of nano-confined water: The viscoelastic dynamics of nano-confined water is studied by means of\natomic force microscopy (AFM). We observe a nonlinear viscoelastic behavior\nremarkably similar to that widely observed in metastable complex fluids. We\nshow that the origin of the measured nonlinear viscoelasticity in nano-confined\nwater is a strain rate dependent relaxation time and slow dynamics. By\nmeasuring the viscoelastic modulus at different frequencies and strains, we\nfind that the intrinsic relaxation time of nano-confined water is in the range\n0.1-0.0001 s, orders of magnitude longer than that of bulk water, and\ncomparable to the dielectric relaxation time measured in supercooled water at\n170-210 K.",
        "positive": "Extracting the Pair Distribution Function of Liquids and Liquid-Vapor\n  Surfaces by Grazing Incidence X-ray Diffraction Mode: We show that the structure factor $S(q)$ of water can be obtained from X-ray\nsynchrotron experiments at grazing angle of incidence (in reflection mode) by\nusing a liquid surface diffractometer. The corrections used to obtain $S(q)$\nself-consistently are described. Applying these corrections to scans at\ndifferent incident beam angles (above the critical angle) collapses the\nmeasured intensities into a single master curve, without fitting parameters,\nwhich within a scale factor yields $S(q)$. Performing the measurements below\nthe critical angle for total reflectivity yields the structure factor of the\ntop most layers of the water/vapor interface. Our results indicate water\nrestructuring at the vapor/water interface. We also introduce a new approach to\nextract $g(r)$, the pair distribution function (PDF), by expressing the PDF as\na linear sum of Error functions whose parameters are refined by applying a\nnon-linear least square fit method. This approach enables a straightforward\ndetermination of the inherent uncertainties in the PDF. Implications of our\nresults to previously measured and theoretical predictions of the PDF are also\ndiscussed."
    },
    {
        "anchor": "Ion-dependent DNA Configuration in Bacteriophage Capsids: Bacteriophages densely pack their long dsDNA genome inside a protein capsid.\nThe conformation of the viral genome inside the capsid is consistent with a\nhexagonal liquid crystalline structure. Experiments have confirmed that the\ndetails of the hexagonal packing depend on the electrochemistry of the capsid\nand its environment. In this work, we propose a biophysical model that\nquantifies the relationship between DNA configurations inside bacteriophage\ncapsids and the types and concentrations of ions present in a biological\nsystem. We introduce an expression for the free energy which combines the\nelectrostatic energy with contributions from bending of individual segments of\nDNA and Lennard-Jones-type interactions between these segments. The equilibrium\npoints of this energy solve a partial differential equation that defines the\ndistributions of DNA and the ions inside the capsid. We develop a computational\napproach that allows us to simulate much larger systems than what is currently\npossible using the existing simulations, typically done at a molecular level.\nIn particular, we are able to estimate bending and repulsion between DNA\nsegments as well as the full electrochemistry of the solution, both inside and\noutside of the capsid. The numerical results show good agreement with existing\nexperiments and molecular dynamics simulations for small capsids.",
        "positive": "Tuning the Stabilization Mechanism of Nanoparticle-Regulated Complex\n  Fluids: In nanoparticle haloing, charged nanoparticles have been found to enhance the\nstability of colloidal suspensions by forming a non-adsorbing layer surrounding\nneutral colloids which induces an electrostatic repulsion between them.\nHowever, there has been some debate that nanoparticles may directly deposit\nonto the colloidal surfaces and that the stabilization mechanism relies on\nnanoparticle adsorption. In this study, we have found that these two mechanisms\ncontrol the stability of colloidal suspensions across a continuum over\nincreasing nanoparticle concentrations. AFM force measurements showed that\nhighly charged zirconia nanoparticles built up an electrostatic repulsion\nbetween negligibly charged silica surfaces, preventing them from aggregating.\nThe follow-up adsorption measurements and force modeling indicated that minor\nadsorption of nanoparticles is expected at volume fractions of 10-5 to 10-3,\nbut the amount of nanoparticle adsorption dramatically increases with\nincreasing the nanoparticle volume fraction beyond 10-3. Based on these\nresults, we propose that the fundamental mechanism of nanoparticle-regulated\nstabilization is nanoparticle haloing at low nanoparticle concentrations which\ntransitions to adsorption at higher concentrations. Accordingly, at a\nnanoparticle volume fraction of around 10-3 where the transition happens, the\nstabilization can be influenced by both nanoparticle haloing and adsorption."
    },
    {
        "anchor": "Phase Transitions and Dynamics in Bulk and Interfacial Water: New experiments for water at the surface of proteins at very low temperature\ndisplay intriguing dynamic behaviors. The extreme conditions of these\nexperiments make it difficult to explore the wide range of thermodynamic state\npoints needed to offer a suitable interpretation. Detailed simulations suffer\nthe same problem, where equilibration times at low temperature become\nunreasonably long. We show how Monte Carlo simulations and mean field\ncalculations of a tractable model of water help interpret the experimental\nresults. Here we summarize the results for bulk water and investigate the\nthermodynamic and dynamic properties of supercooled water at an interface.",
        "positive": "Gas-Liquid Coexistence in the Primitive Model for Water: We evaluate the location of the gas-liquid coexistence line and of the\nassociated critical point for the primitive model for water (PMW), introduced\nby Kolafa and Nezbeda [J. Kolafa and I. Nezbeda, Mol. Phys. 61, 161 (1987)].\nBesides being a simple model for a molecular network forming liquid, the PMW is\nrepresentative of patchy proteins and novel colloidal particles interacting\nwith localized directional short-range attractions. We show that the gas-liquid\nphase separation is metastable, i.e. it takes place in the region of the phase\ndiagram where the crystal phase is thermodynamically favored, as in the case of\narticles interacting via short-range attractive spherical potentials.\nDifferently from spherical potentials, we do not observe crystallization close\nto the critical point. The region of gas-liquid instability of this patchy\nmodel is significantly reduced as compared to equivalent models of spherically\ninteracting particles, confirming the possibility of observing kinetic arrest\nin an homogeneous sample driven by bonding as opposed to packing."
    },
    {
        "anchor": "Inherent Structure Landscape of Hard Spheres Confined to Narrow\n  Cylindrical Channels: The inherent structure landscape for a system of hard spheres confined to a\nhard cylindrical channel, such that spheres can only contact their first and\nsecond neighbours, is studied using an analytical model that extends previous\nresults [Phys. Rev. Lett. 115, 025702 (2015)] to provide a comprehensive\npicture of jammed packings over a range of packing densities. In the model, a\npacking is described as an arrangement of $k$ helical sections, separated by\ndefects, that have alternating helical twist directions and where all spheres\nsatisfy local jamming constraints. The structure of each helical section is\ndetermined by a single helical twist angle, and a jammed packing is obtained by\nminimizing the length of the channel per particle with respect to the $k$\nhelical section angles. An analysis of a small system of $N=20$ spheres shows\nthat the basins on the inherent structure landscape associated with these\nhelical arrangements split into a number of distinct jammed states separated by\nlow barriers giving rise to a degree of hierarchical organization. The model\naccurately predicts the geometric properties of packings generated using the\nLubachevsky and Stillinger compression scheme ($N=10^4$) and provides insight\ninto the nature of the probability distribution of helical section lengths.",
        "positive": "Unconventional singularities, scale separation and energy balance in\n  frictional rupture: A widespread framework for understanding frictional rupture, such as\nearthquakes along geological faults, invokes an analogy to ordinary cracks. A\ndistinct feature of ordinary cracks is that their near edge fields are\ncharacterized by a square root singularity, which is intimately related to the\nexistence of strict dissipation-related lengthscale separation and\nedge-localized energy balance. Yet, the interrelations between the singularity\norder, lengthscale separation and edge-localized energy balance in frictional\nrupture are not fully understood, even in physical situations in which the\nconventional square root singularity remains approximately valid. Here we\ndevelop a macroscopic theory that shows that the generic rate-dependent nature\nof friction leads to deviations from the conventional singularity, and that\neven if this deviation is small, significant non-edge-localized rupture-related\ndissipation emerges. The physical origin of the latter, which is predicted to\nvanish identically in the crack analogy, is the breakdown of scale separation\nthat leads an accumulated spatially-extended dissipation, involving macroscopic\nscales. The non-edge-localized rupture-related dissipation is also predicted to\nbe position dependent. The theoretical predictions are quantitatively supported\nby available numerical results, and their possible implications for earthquake\nphysics are discussed."
    },
    {
        "anchor": "Comment on \"Replica Symmetry Breaking in Trajectories of a Driven\n  Brownian Particle\": We comment on a Letter [Phys. Rev. Lett. 115, 080605 (2015), arXiv:1411.1816]\n\"Replica symmetry breaking in trajectories of a driven Brownian particle\" and\nauthor reply [arXiv:1805.10474]",
        "positive": "A computational study of a transversely propelling polymer and passive\n  particles: Using Langevin dynamics simulations, we study a system of transversely\npropelling filament and passive Brownian particles. We consider a polymer whose\nmonomers experience a constant propulsion force perpendicular to the local\ntangent in the presence of passive particles undergoing thermal fluctuations in\ntwo dimensions. We demonstrate that the sideways propelling polymer can act as\na sweeper to collect the passive Brownian particles, mimicking a shuttle-cargo\nsystem. The number of particles the polymer collects during its motion\nincreases with time and finally saturates to a maximum number. Moreover, the\nvelocity of the polymer decreases as the particles get trapped due to the extra\ndrag they generate. Rather than going to zero, the velocity eventually reaches\na terminal value close to the contribution from the thermal velocity when it\ncollects the maximum load. We show that, apart from the length of the polymer,\nthe propulsion strength and the number of passive particles are deciding\nfactors for the maximum trapped particles. In addition, we demonstrate that the\ncollected particles arrange themselves in a triangular, closed, packed state,\nsimilar to what has been observed in"
    },
    {
        "anchor": "Order-disorder transition and alignment dynamics of a block copolymer\n  under high magnetic fields by in situ x-ray scattering: We present results of temperature resolved scattering studies of a liquid\ncrystalline block copolymer undergoing an order-disorder transition (ODT) in\nthe presence of magnetic fields and time-resolved measurements during\nisothermal field annealing at sub-ODT temperatures. In each case, field\ninteractions produced strongly textured mesophases with the cylindrical\nmicrodomains aligned parallel to the field. We find there is no measurable\nfield-induced shift in the ODT temperature ($T_{ODT}$) which suggests that\nselective melting does not play a role in mesophase alignment during isothermal\nexperiments. Our data indicate instead that sub-ODT alignment occurs by slow,\nlarge scale grain rotation whereas alignment during cooling from the disordered\nmelt is rapid and driven by the nucleation of weakly ordered but preferentially\naligned material. We identify an optimum sub-cooling that maximizes alignment\nduring isothermal field annealing. This is corroborated by a simple model\nincorporating the competing effects of an exponentially decreasing mobility and\ndivergent, increasing magnetic anisotropy on cooling below $T_{ODT}$. The\nabsence of measurable field-effects on $T_{ODT}$ is consistent with rough\nestimates derived from the relative magnitudes of the free energy due to field\ninteraction and the enthalpy of the isotropic-LC transition.",
        "positive": "A Monte-Carlo approach to Poisson-Boltzmann like free energy functionals: A simple technique is proposed for numerically determining equilibrium ion\ndistribution functions belonging to free energies of the Poisson-Boltzmann\ntype. The central idea is to perform a conventional Monte-Carlo simulation\nusing the free energy as the \"Hamiltonian\" entering the Metropolis criterion\nand the spatially discretized density as degrees of freedom. This approach is\ncomplementary to the possibility of numerically solving the differential\nequations corresponding to the variational problem, but it is much easier to\nimplement and to generalize. Its utility is demonstrated in two examples:\nvalence mixtures and hard core interactions of ions surrounding a charged rod."
    },
    {
        "anchor": "Reduced integration schemes in micromorphic computational homogenization\n  of elastomeric mechanical metamaterials: Exotic behaviour of mechanical metamaterials often relies on an internal\ntransformation of the underlying microstructure triggered by its local\ninstabilities, rearrangements, and rotations. Depending on the presence and\nmagnitude of such a transformation, effective properties of a metamaterial may\nchange significantly. To capture this phenomenon accurately and efficiently,\nhomogenization schemes are required that reflect microstructural as well as\nmacro-structural instabilities, large deformations, and non-local effects. To\nthis end, a micromorphic computational homogenization scheme has recently been\ndeveloped, which employs the particular microstructural transformation as a\nnon-local mechanism, magnitude of which is governed by an additional coupled\npartial differential equation. Upon discretizing the resulting problem it turns\nout that the macroscopic stiffness matrix requires integration of macro-element\nbasis functions as well as their derivatives, thus calling for a higher-order\nintegration rules. Because evaluation of constitutive law in multiscale schemes\ninvolves an expensive solution of a non-linear boundary value problem,\ncomputational efficiency can be improved by reducing the number of integration\npoints. Therefore, the goal of this paper is to investigate reduced-order\nschemes in computational homogenization, with emphasis on the stability of the\nresulting elements. In particular, arguments for lowering the order of\nintegration from the expensive mass-matrix to a cheaper stiffness-matrix\nequivalent are first outlined. An efficient one-point integration quadrilateral\nelement is then introduced and proper hourglass stabilization discussed.\nPerformance of the resulting set of elements is finally tested on a benchmark\nbending example, showing that we achieve accuracy comparable to the full\nquadrature rules.",
        "positive": "Self-assembly of core-corona particles confined in a circular box: Using Monte Carlo simulations, we study the assembly of colloidal particles\ninteracting via isotropic core-corona potentials in two dimensions and confined\nin a circular box. We explore the structural variety at low temperatures as\nfunction of the number of particles (N) and the size of the confining box and\nfind a rich variety of patterns that are not observed in unconfined flat space.\nFor a small number of particles (N<=6), we identify the zero-temperature\nminimal energy configurations at a given box size and we construct the phase\ndiagram as function of temperature and box radius for the specific case of N=4.\nWhen the number of particles is large (N>=100), we distinguish different\nregimes that appear in route towards close packing configurations as the box\nsize decreases. These regimes are characterized by the increase in the number\nof branching points and their coordination number. In contrast to the case of\nconfined hard disks, we obtain open structures with unexpected highly\nanisotropic character in spite of the isotropy of the interactions and of the\nconfinement. Our findings show that confined core-corona particles can be a\nsuitable system to engineer particles with highly complex internal structure\nthat may serve as building blocks in hierarchical assembly."
    },
    {
        "anchor": "Statistical analysis of phase formation in 2D colloidal systems: Colloidal systems offer unique opportunities for the study of phase formation\nand structure since their characteristic length scales are accessible to\nvisible light. As a model system the two dimensional assembly of colloidal\nmagnetic and non-magnetic particles dispersed in a ferrofluid (FF) matrix is\nstudied by transmission optical microscopy. We present a method to\nstatistically evaluate images with thousands of particles and map phases by\nextraction of local variables. Different lattice structures and long-range\nconnected branching chains are observed, when tuning the effective magnetic\ninteraction and varying particle ratios.",
        "positive": "Entropy maximization in the force network ensemble for granular solids: A long-standing issue in the area of granular media is the tail of the force\ndistribution, in particular whether this is exponential, Gaussian, or even some\nother form. Here we resolve the issue for the case of the force network\nensemble in two dimensions. We demonstrate that conservation of the total area\nof a reciprocal tiling, a direct consequence of local force balance, is crucial\nfor predicting the local stress distribution. Maximizing entropy while\nconserving the tiling area and total pressure leads to a distribution of local\npressures with a generically Gaussian tail that is in excellent agreement with\nnumerics, both with and without friction and for two different contact\nnetworks."
    },
    {
        "anchor": "High--order jamming crossovers and density anomalies: We demonstrate the existence of high--order jamming crossovers in systems of\nparticles with repulsive contact interactions, which originate from the\ncollapse of successive coordination shells. At zero temperature, these\ncrossovers induce an anomalous behavior of the bulk modulus, which varies\nnon--monotonically with the density, while at finite temperature they induce\ndensity anomalies consisting in an increased diffusivity upon isothermal\ncompression and in a negative thermal expansion coefficient. We rationalize the\ndependence of these crossovers on the softness of the interaction potential,\nand relate the jamming crossovers and the anomalous diffusivity through the\ninvestigation of the vibrational spectrum.",
        "positive": "Nematic-Wetted Colloids in the Isotropic Phase: Pairwise Interaction,\n  Biaxiality and Defects: We calculate the interaction between two spherical colloidal particles\nembedded in the isotropic phase of a nematogenic liquid. The surface of the\nparticles induces wetting nematic coronas that mediate an elastic interaction.\nIn the weak wetting regime, we obtain exact results for the interaction energy\nand the texture, showing that defects and biaxiality arise, although they are\nnot topologically required. We evidence rich behaviors, including the\npossibility of reversible colloidal aggregation and dispersion. Complex\nanisotropic self-assembled phases might be formed in dense suspensions."
    },
    {
        "anchor": "Quantifying nanoscale charge density features of contact-charged\n  surfaces with an FEM/KPFM-hybrid approach: Kelvin probe force microscopy (KPFM) is a powerful tool for studying contact\nelectrification at the nanoscale, but converting KPFM voltage maps to charge\ndensity maps is non-trivial due to long-range forces and complex system\ngeometry. Here we present a strategy using finite element method (FEM)\nsimulations to determine the Green's function of the KPFM\nprobe/insulator/ground system, which allows us to quantitatively extract\nsurface charge. Testing our approach with synthetic data, we find that\naccounting for the AFM tip, cone and cantilever are necessary to recover a\nknown input, and that commonly applied heuristics and approximations lead to\ngross miscalculation. Applying it to experimental data, we demonstrate its\ncapacity to extract realistic surface charge densities and fine details from\ncontact charged surfaces. Our method gives a straightforward recipe to convert\nqualitative KPFM voltage data into quantitative charge data over a range of\nexperimental conditions, enabling quantitative contact electrification\nexperiments at the nanoscale.",
        "positive": "Low temperature behaviour and glass line of the symmetrical colloidal\n  electrolyte: We report on the low temperature behaviour of the colloidal electrolyte by\nmeans of Molecular Dynamics simulations, where the electrostatic interactions\nwere modeled using effective screened interactions. As in previous works, we\nhave found a region of gas-liquid coexistence located in the low $T$- low\n$\\rho$ region. At temperatures much lower than the critical one, the system\ncannot reach equilibrium, that is, the gas-liquid transition is arrested. Two\ndifferent mechanisms have been identified to cause arrest: gelation in the\nlowest $T$ and crowding at intermediate $T$ values, the latter associated with\nthe crossing point between the binodal and the glass line. To test the latter,\nthe dynamics of the colloidal electrolyte near this crossing point has been\ncomputed and compared to the universal predictions of the ideal MCT. As in\nother glass-forming liquids, we found good agreement between this mean field\ntheory and the dynamics of this complex system, although it fails just at the\ntransition. Interestingly, in this region we found that the dynamics of this\nsystem is driven mainly by the steric interactions, showing all the typical\nproperties of a repulsive colloidal glass. Finally, the isodiffusivity lines\nshow that in this system with short range attractions, there is no re-entrant\nglass phenomenon, as opposed to monocomponent systems."
    },
    {
        "anchor": "Nonequilibrium thermodynamics and glassy rheology: Mechanically driven glassy systems and complex fluids exhibit a wealth of\nrheological behaviors that call for theoretical understanding and predictive\nmodeling. A distinct feature of these nonequilibrium systems is their\ndynamically evolving state of structural disorder, which determines their\nrheological responses. Here we highlight a recently developed nonequilibrium\nthermodynamic framework in which the structural state is characterized by an\nevolving effective disorder temperature that may differ from the ordinary\nthermal temperature. The specific properties of each physical system of\ninterest are described by a small set of coarse-grained internal state\nvariables and their associated energies and entropies. The dynamics of the\ninternal variables, together with the flow of energy and entropy between the\ndifferent parts of the driven system, determine continuum-level rheological\nconstitutive laws. We conclude with brief descriptions of several successful\napplications of this framework.",
        "positive": "Humidity Effects and Aging Behavior in Granular Media: We present a study of humidity effects on the maximum stability angle in\ngranular media. We show that a granular medium of small glass beads exhibits\naging properties : the first avalanche angle increases logarithmically with the\nresting time of the pile. This aging behavior is found to depend on the\nrelative humidity of the surrounding atmosphere. A short interpretation of this\neffect, based on a model of activated capillary condensation, is proposed."
    },
    {
        "anchor": "Colloids Exposed to Random Potential Energy Landscapes: from Particle\n  Number Density to Particle-Potential and Particle-Particle Interactions: Colloidal particles were exposed to a random potential energy landscape\n(rPEL) that has been created optically via a speckle pattern. The mean particle\ndensity as well as the potential roughness, i.e. the disorder strength, were\nvaried. The local probability density of the particles as well as its main\ncharacteristics were determined. For the first time, the disorder-averaged pair\ndensity correlation function and an analogue of the Edwards-Anderson order\nparameter, which quantifies the correlation of the mean local density among\ndisorder realisations, were measured experimentally and shown to be consistent\nwith replica liquid state theory results.",
        "positive": "Rethinking the Transient Network Concept in Entangled Polymer Rheology: The classical rheological theories of entangled polymeric liquids are built\nupon two pillars: Gaussian statistics of entanglement strands and the\nassumption that the stress arises exclusively from the change of intramolecular\nconfiguration entropy. We show that these two hypotheses are not supported by\nmolecular dynamics simulations of polymer melts. Specifically, the segment\ndistribution functions at the entanglement length scale and below deviate\nconsiderably from the theoretical predictions, in both the equilibrium and\ndeformed states. Further conformational analysis reveals that the intrachain\nentropic stress at the entanglement length scale is substantially smaller than\nthe total stress, indicative of a considerable contribution from interchain\nentropy. Lastly, the relation between entanglement strand entropic stress and\nmacroscopic stress exhibits a bifurcation behavior during deformation and\nstress relaxation, which cannot be accounted for by the classical theories."
    },
    {
        "anchor": "A Geometric Mapping from Rectilinear Material Orthotropy to Isotropy:\n  Insights to Plates and Shells: Orthotropic shell structures are ubiquitous in biology and engineering, from\nbacterial cell walls to reinforced domes. We present a rescaling transformation\nthat maps an orthotropic shallow shell to an isotropic one with a different\nlocal geometry. The mapping is applicable to any shell section for which the\nmaterial orthotropy directions match the principal curvature directions,\nassuming a commonly used form for the orthotropic shear modulus. Using the\nrescaling transformation, we derive exact expressions for the buckling pressure\nas well as the linear indentation response of orthotropic cylinders and general\nellipsoids of revolution, which we verify against numerical simulations. Our\nanalysis disentangles the separate contributions of geometric and material\nanisotropy to shell rigidity. In particular, we identify the geometric mean of\northotropic elastic constants as the key quantifier of material stiffness,\nplaying a role akin to the Gaussian curvature which captures the geometric\nstiffness contribution. Besides providing insights into the mechanical response\nof orthotropic shells, our work rigorously establishes the validity of\nisotropic approximations to orthotropic shells and also identifies situations\nin which these approximations might fail.",
        "positive": "Wrinkling reveals a new isometry of pressurized elastic shells: We consider the point indentation of a pressurized, spherical elastic shell.\nPreviously it was shown that such shells wrinkle once the indentation reaches a\nthreshold value. Here, we study the behaviour of this system beyond the onset\nof instability. We show that rather than simply approaching the classical\n`mirror-buckled' shape, the wrinkled shell approaches a new, universal shape\nthat reflects a nontrivial type of isometry. For a given indentation depth,\nthis ``asymptotic isometry\", which is only made possible by wrinkling, is\nreached in the doubly asymptotic limit of weak pressure and vanishing shell\nthickness."
    },
    {
        "anchor": "What is the origin of chirality in the cholesteric phase of virus\n  suspensions ?: We report a study of the cholesteric phase in monodisperse suspensions of the\nrod-like virus fd sterically stabilized with the polymer polyethylene glycol\n(PEG). After coating the virus with neutral polymers, the phase diagram and\nnematic order parameter of the fd-PEG system then become independent of ionic\nstrength. Surprisingly, the fd-PEG suspensions not only continue to exhibit a\ncholesteric phase, which means that the grafted polymer does not screen all\nchiral interactions between rods, but paradoxically the cholesteric pitch of\nthis sterically stabilized fd-PEG system varies with ionic strength.\nFurthermore, we observe that the cholesteric pitch decreases with increasing\nviral contour length, in contrast to theories which predict the opposite trend.\nDifferent models of the origin of chirality in colloidal liquid crystals are\ndiscussed.",
        "positive": "A Novel Method to Probe the Pronounced Growth of Correlation Lengths in\n  an Active Glass-forming Liquids using Elongated Probe: The growth of correlation lengths in equilibrium glass-forming liquids near\nthe glass transition is considered a critical finding in the quest to\nunderstand the physics of glass formation. These understandings helped us\nunderstand various dynamical phenomena observed in supercooled liquids. It is\nknown that at least two different length scales exist - one is of thermodynamic\norigin, while the other is dynamical in nature. Recent observations of glassy\ndynamics in biological and synthetic systems where the external or internal\ndriving source controls the dynamics, apart from the usual thermal noise, led\nto the emergence of the field of active matter. A question of whether the\nphysics of glass formation in these active systems is also accompanied by\ngrowing dynamic and static lengths is indeed timely. In this article, we probe\nthe growth of dynamic and static lengths in a model active glass system using\nrod-like elongated probe particles, an experimentally viable method. We show\nthat the dynamic and static lengths in these non-equilibrium systems grow much\nmore rapidly than their passive counterparts. We then offer an understanding of\nthe violation of the Stokes-Einstein relation and Stokes-Einstein-Debye\nrelation using these lengths via a scaling theory."
    },
    {
        "anchor": "Relating microswimmer synthesis to rheotactic tunability: We explore the behavior of micron-scale autophoretic Janus (Au/Pt) rods,\nhaving various Au/Pt length ratios, swimming near a wall in an imposed\nbackground flow. We find that their ability to robustly orient and move\nupstream, i.e. to rheotax, depends strongly on the Au/Pt ratio, which is easily\ntunable in synthesis. Numerical simulations of swimming rods actuated by a\nsurface slip show a similar rheotactic tunability when varying the location of\nthe surface slip versus surface drag. Slip location determines whether swimmers\nare Pushers (rear-actuated), Pullers (front-actuated), or in between. Our\nsimulations and modeling show that Pullers rheotax most robustly due to their\nlarger tilt angle to the wall, which makes them responsive to flow gradients.\nThus, rheotactic response infers the nature of difficult to measure flow-fields\nof an active particle, establishes its dependence on swimmer type, and shows\nhow Janus rods can be tuned for flow responsiveness. We demonstrate the\neffectiveness of a simple geometric sieve for rheotactic ability.",
        "positive": "Computational Reverse-Engineering Analysis for Scattering Experiments\n  for Form Factor and Structure Factor Determination ('P(q) and S(q) CREASE'): In this paper we present an open-source machine learning (ML) accelerated\ncomputational method to analyze small-angle scattering profiles [I(q) vs. q]\nfrom concentrated macromolecular solutions to simultaneously obtain the form\nfactor P(q) (e.g., dimensions of a micelle) and structure factor S(q) (e.g.,\nspatial arrangement of the micelles) without relying on analytical models. This\nmethod builds on our recent work on Computational Reverse Engineering Analysis\nfor Scattering Experiments (CREASE) that has either been applied to obtain P(q)\nfrom dilute macromolecular solutions (where S(q) ~1) or to obtain S(q) from\nconcentrated particle solution when the P(q) is known (e.g., sphere form\nfactor). This paper's newly developed CREASE that calculates P(q) and S(q),\ntermed as 'P(q) and S(q) CREASE' is validated by taking as input I(q) vs. q\nfrom in silico structures of known polydisperse core(A)-shell(B) micelles in\nsolutions at varying concentrations and micelle-micelle aggregation. We\ndemonstrate how 'P(q) and S(q) CREASE' performs if given two or three of the\nrelevant scattering profiles - Itotal(q), IA(q), and IB(q) - as inputs; this\ndemonstration is meant to guide experimentalists who may choose to do\nsmall-angle X-ray scattering (for total scattering from the micelles) and/or\nsmall-angle neutron scattering with appropriate contrast matching to get\nscattering solely from one or the other component (A or B). After validation of\n'P(q) and S(q) CREASE' on in silico structures, we present our results\nanalyzing small-angle neutron scattering profiles from a solution of core-shell\ntype surfactant coated nanoparticles with varying extents of aggregation."
    },
    {
        "anchor": "Deformations of glassy polymers in very low temperature regime within\n  cylindrical micropores: The deformation kinetics for glassy polymers confined in microscopic domain\nat very low temperature regime was investigated using a transition-rate-state\ndependent model considering the shear thinning behavior which means, once\nmaterial being subjected to high shear rates, the viscosity diminishes with\nincreasing shear rate. The preliminary results show that there might be nearly\nfrictionless fields for rate of deformation due to the almost vanishing shear\nstress in micropores at very low temperature regime subjected to some surface\nconditions : The relatively larger roughness (compared to the macroscopic\ndomain) inside micropores and the slip. As the pore size decreases, the\nsurface-to-volume ratio increases and therefore, surface roughness will greatly\naffect the deformation kinetics in micropores.\n  By using the boundary perturbation method, we obtained a class of temperature\nand activation energy dependent fields for the deformation kinetics at low\ntemperature regime with the presumed small wavy roughness distributed along the\nwalls of an cylindrical micropore. The critical deformation kinetics of the\nglassy matter is dependent upon the temperature, activation energy, activation\nvolume, orientation dependent and is proportional to the (referenced) shear\nrate, the slip length, the amplitude and the orientation of the wavy-roughness.",
        "positive": "Active colloids at fluid interfaces: If an active Janus particle is trapped at the interface between a liquid and\na fluid, its self-propelled motion along the interface is affected by a net\ntorque on the particle due to the viscosity contrast between the two adjacent\nfluid phases. For a simple model of an active, spherical Janus colloid we\nanalyze the conditions under which translation occurs along the interface and\nwe provide estimates of the corresponding persistence length. We show that\nunder certain conditions the persistence length of such a particle is\nsignificantly larger than the corresponding one in the bulk liquid, which is in\nline with the trends observed in recent experimental studies."
    },
    {
        "anchor": "Theory of light-activated catalytic Janus particles: We study the dynamics of active Janus particles that self-propel in solution\nby light-activated catalytic decomposition of chemical \"fuel.\" We develop an\nanalytical model of a photo-active self-phoretic particle that accounts for\n\"self-shadowing\" of the light by the opaque catalytic face of the particle. We\nfind that self-shadowing can drive \"phototaxis\" (rotation of the catalytic cap\ntowards the light source) or \"anti-phototaxis,\" depending on the properties of\nthe particle. Incorporating the effect of thermal noise, we show that the\ndistribution of particle orientations is captured by a Boltzmann distribution\nwith a nonequilibrium effective potential. Furthermore, the mean vertical\nvelocity of phototactic (anti-phototactic) particles exhibits a superlinear\n(sublinear) dependence on intensity. Overall, our findings show that\nphoto-active particles exhibit a rich \"tactic\" response to light, which could\nbe harnessed to program complex three-dimensional trajectories.",
        "positive": "Design of conditions for emergence of self-replicators: A self-replicator is usually understood to be an object of definite form that\npromotes the conversion of materials in its environment into a nearly identical\ncopy of itself. The challenge of engineering novel, micro- or nano-scale\nself-replicators has attracted keen interest in recent years, both because\nexponential amplification is an attractive method for generating high yields of\nspecific products, and also because self-reproducing entities have the\npotential to be optimized or adapted through rounds of iterative selection.\nSubstantial steps forward have been achieved both in the engineering of\nparticular self-replicating molecules, and also in characterizing the physical\nbasis for possible mechanisms of self-replication. At present, however, there\nis need for a theoretical treatment of what physical conditions are most\nconducive to the emergence of novel self-replicating structures from a\nreservoir of building blocks on a desired time-scale. Here we report progress\nin addressing this need. By analyzing the dynamics of a generic class of\nheterogeneous particle mixtures whose reaction rates emerge from basic physical\ninteractions, we demonstrate that the spontaneous discovery of self-replication\nis controlled by relatively generic features of the chemical space, namely: the\ndispersion in the distribution of reaction timescales and bound-state energies.\nBased on this analysis, we provide quantitative criteria that may aid\nexperimentalists in designing a system capable of producing self-replicators,\nand in estimating the likely timescale for exponential growth to start."
    },
    {
        "anchor": "Posture Noise and the Measured Probability to Fall: Experimental evidence is presented connecting small fluctuations in the\nposture of a quiet standing subject and the probability that the subject will\nhave an accidental fall within a time period of one year. The data can be\nunderstood on the basis of random velocity fluctuations providing kinetic\nenergy in dynamical posture modes. The kinetic energy can activate a transition\nover the a potential energy barrier which keeps subjects in a metastable\nstanding mode. The probability for a fall then follows an Arrhenius activation\nlaw.",
        "positive": "Radial and axial segregation in horizontal rotating cylinders studied by\n  Magnetic Resonance Imaging (MRI): The dynamics of granular materials, mostly radial and axial segregation in\nhorizontal rotating cylinders filled with millet and poppy seeds, is studied by\nMagnetic Resonance Imaging (MRI). For the first time, full 3D structures and\nreal-time 2D MRI movies showing the progress of segregation over many hours are\nreported. Data are acquired with sufficiently high temporal and in-plane\nspatial resolutions (74 ms and 0.94 mm \\times 0.94 mm, respectively), giving\nnew insights into the underlying mechanisms. The millet and poppy mixture\ncomposition is calibrated based on the signal intensity and is quantified\nthroughout segregation. As for radial segregation, millet and poppy mixture\ncore formation is observed in cylinders of 75% and 82% filling level. The size\nof the core is calculated and the avalanche layer thickness is therefore\ndetermined. 2D MRI movies showing real-time radial segregation suggests that\ninitial radial segregation is due to the stopping and percolation of poppy\nseeds. Axial segregation is characterized by the formation, traveling and\nmerging of poppy-rich bands. In all cases studied, the formation of poppy-rich\nbands is observed, after which individual bands start to travel at \\sim 3 \\mu m\ns^{-1} until they are within \\sim 3 cm of a stationary band. Adjacent bands\nthen merge into a single, enlarged poppy band as millet seeds move out of the\nmerging region. In both radial and axial segregation, core diffusion is shown\nto be another mechanism pathway for segregation besides the free surface."
    },
    {
        "anchor": "Theory of liquids: from excitations to thermodynamics: Of the three basic states of matter, liquid is perhaps the most complex.\nWhile its flow properties are described by fluid mechanics, its thermodynamic\nproperties are often neglected, and for many years it was widely believed that\na general theory of liquid thermodynamics was unattainable. In recent decades\nthat view has been challenged, as new advances have finally enabled us to\nunderstand and describe the thermodynamic properties of liquids. This book\nexplains the recent developments in theory, experiment and modelling that have\nenabled us to understand the behaviour of excitations in liquids and the impact\nof this behaviour on heat capacity and other basic properties. Presented in\nplain language with a focus on real liquids and their experimental properties,\nthis book is a useful reference text for researchers and graduate students in\ncondensed matter physics and chemistry, as well as for advanced courses\ncovering the theory of liquids.",
        "positive": "Force and flow transition in plowed granular media: We use plate drag to study the response of granular media to localized\nforcing as a function of volume fraction, $\\phi$. A bifurcation in the force\nand flow occurs at the onset of dilatancy, $\\phi_c.$ Below $\\phi_c$ rapid\nfluctuations in the drag force, $F_D,$ are observed. Above $\\phi_c$\nfluctuations in $F_D$ are periodic and increase with $\\phi$. Velocity field\nmeasurements indicate that the bifurcation in $F_D$ results from the formation\nof stable shear bands above $\\phi_c$ which are created and destroyed\nperiodically during drag. A friction-based model captures the dynamics for\n$\\phi>\\phi_c$."
    },
    {
        "anchor": "Liquid Front Profiles Affected by Entanglement-induced Slippage: Hydrodynamic slippage plays a crucial role in the flow dynamics of thin\npolymer films, as recently shown by the analysis of the profiles of liquid\nfronts. For long-chained polymer films it was reported that a deviation from a\nsymmetric profile is a result of viscoelastic effects. In this Letter, however,\nevidence is given that merely a slip boundary condition at the solid/liquid\ninterface can lead to an asymmetric profile. Dewetting experiments of entangled\npolymer melts on diverse substrates allow a direct comparison of rim\nmorphologies. Variation of molecular weight Mw clearly reveals that slippage\nincreases dramatically above a certain Mw and governs the shape of the rim. The\nresults are in accordance with the theoretical description by de Gennes.",
        "positive": "2D Lattice Liquid Models: A family of novel models of liquid on a 2D lattice (2D lattice liquid models)\nhave been proposed as primitive models of soft-material membrane. As a first\nstep, we have formulated them as single-component, single-layered, classical\nparticle systems on a two-dimensional surface with no explicit viscosity. Among\nthe family of the models, we have shown and constructed two stochastic models,\na vicious walk model and a flow model, on an isotropic regular lattice and on\nthe rectangular honeycomb lattice of various sizes. In both cases, the dynamics\nis governed by the nature of the frustration of the particle movements. By\nsimulations, we have found the approximate functional form of the frustration\nprobability, and peculiar anomalous diffusions in their time-averaged mean\nsquare displacements in the flow model. The relations to other existing\nstatistical models and possible extensions of the models are also discussed."
    },
    {
        "anchor": "Jamming I: A volume function for jammed matter: We introduce a \"Hamiltonian\"-like function, called the volume function,\nindispensable to describe the ensemble of jammed matter such as granular\nmaterials and emulsions from a geometrical point of view. The volume function\nrepresents the available volume of each particle in the jammed systems. At the\nmicroscopic level, we show that the volume function is the Voronoi volume\nassociated to each particle and in turn we provide an analytical formula for\nthe Voronoi volume in terms of the contact network, valid for any dimension. We\nthen develop a statistical theory for the probability distribution of the\nvolumes in 3d to calculate an average volume function coarse-grained at a\nmesoscopic level. The salient result is the discovery of a mesoscopic volume\nfunction inversely proportional to the coordination number. Our analysis is the\nfirst step toward the calculation of macroscopic observables and equations of\nstate using the statistical mechanics of jammed matter, when supplemented by\nthe condition of mechanical equilibrium of jamming that properly defines jammed\nmatter at the ensemble level.",
        "positive": "Thermodynamically self-consistent liquid state theories for systems with\n  bounded potentials: The mean spherical approximation (MSA) can be solved semi-analytically for\nthe Gaussian core model (GCM) and yields - rather surprisingly - exactly the\nsame expressions for the energy and the virial equations. Taking advantage of\nthis semi-analytical framework, we apply the concept of the self-consistent\nOrnstein-Zernike approximation (SCOZA) to the GCM: a state-dependent function K\nis introduced in the MSA closure relation which is determined to enforce\nthermodynamic consistency between the compressibility route and either the\nvirial or energy route. Utilizing standard thermodynamic relations this leads\nto two different differential equations for the function K that have to be\nsolved numerically. Generalizing our concept we propose an\nintegro-differential-equation based formulation of the SCOZA which, although\nrequiring a fully numerical solution, has the advantage that it is no longer\nrestricted to the availability of an analytic solution for a particular system.\nRather it can be used for an arbitrary potential and even in combination with\nother closure relations, such as a modification of the hypernetted chain\napproximation."
    },
    {
        "anchor": "Deviations from Arrhenius dynamics in high temperature liquids, a\n  possible collapse, and a viscosity bound: Liquids realize a highly complex state of matter in which strong competing\nkinetic and interaction effects come to life. As such, liquids are more\nchallenging to understand than either gases or solids generally. In weakly\ninteracting gases, the kinetic effects dominate. By contrast, low temperature\nsolids typically feature far smaller fluctuations about their ground state.\nNotwithstanding their complexity, with the exception of quantum fluids and\nsupercooled liquids, various aspects of common liquid dynamics such as their\ndynamic viscosity are often assumed to be given by rather simple,\nArrhenius-type, activated forms with nearly constant (i.e., temperature\nindependent) energy barriers. In this work, we analyze experimentally measured\nviscosities of numerous liquids far above their equilibrium melting temperature\nto see how well this assumption fares. We find, for the investigated liquids,\nmarked deviations from simple activated dynamics. Even far above their\nequilibrium melting temperatures, as the temperature drops, the viscosity of\nthese liquids increases more strongly than predicted by activated dynamics\ndominated by a single uniform energy barrier. For metallic fluids, the scale of\nthe prefactors of the best Arrhenius fits for the viscosity is typically\nconsistent with that given by the product $nh$ with $n$ the number density and\n$h$ Planck's constant. In various fluids that we examined, $nh$ constitutes a\nlower bound scale on the viscosity. We find that a scaling of the temperature\naxis (complementing that of the viscosity) leads to a partial collapse of the\ntemperature dependent viscosities of different fluids; such a scaling allows\nfor a functional dependence of the viscosity on temperature that includes yet\nis far more general than activated Arrhenius form alone. We speculate on\nrelations between non-Arrhenius dynamics and thermodynamic observables.",
        "positive": "Emergent probability fluxes in confined microbial navigation: When the motion of a motile cell is observed closely, it appears erratic, and\nyet the combination of nonequilibrium forces and surfaces can produce striking\nexamples of organization in microbial systems. While most of our current\nunderstanding is based on bulk systems or idealized geometries, it remains\nelusive how and at which length scale self-organization emerges in complex\ngeometries. Here, using experiments, analytical and numerical calculations we\nstudy the motion of motile cells under controlled microfluidic conditions, and\ndemonstrate that probability flux loops organize active motion even at the\nlevel of a single cell exploring an isolated compartment of nontrivial\ngeometry. By accounting for the interplay of activity and interfacial forces,\nwe find that the boundary's curvature determines the nonequilibrium probability\nfluxes of the motion. We theoretically predict a universal relation between\nfluxes and global geometric properties that is directly confirmed by\nexperiments. Our findings open the possibility to decipher the most probable\ntrajectories of motile cells and may enable the design of geometries guiding\ntheir time-averaged motion."
    },
    {
        "anchor": "Rates of transesterication in epoxy-thiol vitrimers: Vitrimers, an important subset of dynamically crosslinked polymer networks,\nhave many technological applications for their excellent properties, and the\nability to be re-processed through plastic flow above the so-called\nvitrification temperature. We report a simple and efficient method of\ngenerating such adaptive crosslinked networks relying on transesterification\nfor their bond exchange by utilising the `click' chemistry of epoxy and thiols,\nwhich also has the advantage of a low glass transition temperature. We vary the\nchemical structure of thiol spacers to probe the effects of concentration and\nthe local environment of ester groups on the macroscopic elastic-plastic\ntransition. The thermal activation energy of transesterification bond exchange\nis determined for each chemical structure, and for a varying concentration of\ncatalyst, establishing the conditions for the optimal, and for the suppressed\nbond exchange. However, we also discover that the temperature of\nelastic-plastic transition is strongly affected by the stiffness (dynamic\nrubber modulus) of the network, with softer networks having a much lower\nvitrification temperature even when their bond-exchange activation energy is\nhigher. This combination of chemical and physical control factors should help\noptimise the processability of vitrimer plastics.",
        "positive": "Soft Elasticity in Nematic Liquid-Crystal Networks: Liquid-crystal networks consist of weakly crosslinked polymers that are\ncoupled to liquid-crystal molecules. The resultant hybrid system has rich\nelastic properties. We develop a phase field model to describe mechanical\nproperties of a hexagonal liquid-crystal network. The hexagonal liquid-crystal\nnetwork is found to have soft shear deformations. The elastic properties are\npredicted analytically and confirmed with numerical simulations. In addition\nthe model incorporates non-linear elasticity and dislocations or disclinations."
    },
    {
        "anchor": "Particle aggregation by positive dielectrophoresis: Particle aggregates are formed with viable yeast cells (Saccharomyces\ncerevisiae) and bacterial cells (Escherichia coli and Micrococcus luteus), and\nare assembled in an interdigitated-castelled microelectrode using positive\ndielectrophoresis with an alternating current sinusoidal voltage of 2-20 V\npeak-peak at 1 MHz. The height of S. cerevisiae aggregates are increased by the\naddition of the ampholytes N-[2-hydroxyethyl] piperazine-n'-[2-ethanesulfonic\nacid] (HEPES) or e-aminocaproic acid (EACA) due to the resulting rise in\npermittivity of the aqueous solution. The mean height of S. cerevisiae\naggregates in the presence of 1 M HEPES was 25.7 % higher than achieved in an\nampholyte-free solution. Based on the results obtained, a next-generation\ntriangular grooved microelectrode is proposed as an alternative to the\ninterdigitated-castelled microelectrode. This innovation could mark a paradigm\nshift from aggregating particles at specific regions of high electric strength\n(e.g. electrode edge) towards a layer by layer aggregation of particles along a\nmicroelectrode.",
        "positive": "Adsorption of hydrophobic polyelectrolytes as studied by \\emph{in situ}\n  high energy X-Ray reflectivity: A series of well-defined hydrophilic and hydrophobic polyelectrolytes of\nvarious chain lengths $N$ and effective charge fractions $f_{eff}$ have been\nadsorbed onto oppositely charged solid surfaces immersed in aqueous solutions.\n\\emph{In situ} high energy X-ray reflectivity has provided the thickness $h$,\nthe electron density and the roughness of the adsorbed layer in its aqueous\nenvironment. In the case of hydrophobic polyelectrolytes, we have found\n$h\\propto N^0 f_{eff}^{-2/3}$, in agreement with a pearl-necklace conformation\nfor the chains induced by a Rayleigh-like instability."
    },
    {
        "anchor": "The role of friction in the yielding of adhesive non-Brownian\n  suspensions: Yielding behavior is well known in attractive colloidal suspensions. Adhesive\nnon-Brownian suspensions, in which the interparticle bonds are due to\nfinite-size contacts, also show yielding behavior. We use a combination of\nsteady-state, oscillatory and shear-reversal rheology to probe the physical\norigins of yielding in the latter class of materials, and find that yielding is\nnot simply a matter of breaking adhesive bonds, but involves unjamming from a\nshear-jammed state in which the micro-structure has adapted to the direction of\nthe applied load. Comparison with a recent constraint-based rheology model\nshows the importance of friction in determining the yield stress, suggesting\nnovel ways to tune the flow of such suspensions.",
        "positive": "Electroactuation with Single Charge Carrier Ionomers: A simple theory of electromechanical transduction for single-charge-carrier\ndouble-layer electroactuators is developed, in which the ion distribution and\ncurvature are mutually coupled. The obtained expressions for the dependence of\ncurvature and charge accumulation on the applied voltage, as well as the\nelectroactuation dynamics, are compared with literature data. The mechanical-\nor sensor- performance of such electroactuators appears to be determined by\njust three cumulative parameters, with all of their constituents measurable,\npermitting a scaling approach to their design."
    },
    {
        "anchor": "A Micro-mechanical Approach to Model Thermo-Oxidative Aging in\n  Elastomers: This paper presents a micro-mechanical approach to describe the effects of\nthermo-oxidation on the constitutive behavior of aged elastomers at the\nlong-range timescales. In particular, this model focuses on the effects of\nthermo-oxidative aging on the quasi-static mechanical response of elastomer and\ntheir inelastic responses such as Mullins effect and permanent set over time.\nThe model is validated with respect to a comprehensive set of experimental data\ndesigned by Johlitz et al. to capture thermo-oxidative effect on constitutive\nbehavior of elastomers. Besides accuracy, the model is relatively simple and\neasy to fit. It requires ten material parameters, all with clear physical\nmeaning, which can be derived from only one set of experiment.",
        "positive": "The physics of osmotic pressure: The proper application of the virial theorem to the origin of osmotic\npressure provides a simple, vivid and complete explanation of the physical\nprocesses involved; osmosis is driven by differential solvent pressures. This\nsimple and intuitive notion is widely disregarded, but the virial theorem\nallows an exact formulation and unifies a number of different treatments. It is\nclosely related to a kinetic treatment devised by Ehrenfest over 100 years ago."
    },
    {
        "anchor": "Jamming of packings of frictionless particles with and without shear: By minimizing the enthalpy of packings of frictionless particles, we obtain\njammed solids at desired pressures and hence investigate the jamming transition\nwith and without shear. Typical scaling relations of the jamming transition are\nrecovered in both cases. In contrast to systems without shear, shear-driven\njamming transition occurs at a higher packing fraction and the jammed solids\nare more rigid with an anisotropic force network. Furthermore, by introducing\nthe macro-friction coefficient, we propose an explanation of the packing\nfraction gap between sheared and non-sheared systems at fixed pressure.",
        "positive": "Solitary waves on vortex lines in Ginzburg--Landau models: Axisymmetric disturbances that preserve their form as they move along the\nvortex lines in uniform Bose-Einstein condensates are obtained numerically by\nthe solution of the Gross-Pitaevskii equation. A continuous family of such\nsolitary waves is shown in the momentum ($p$) -- substitution energy\n($\\hat{\\cal E}$) plane with $p\\to 0.09 \\rho \\kappa^3/c^2, \\hat{\\cal E}\\to 0.091\n\\rho \\kappa^3/c$ as $U \\to c$, where $\\rho$ is the density, $c$ is the speed of\nsound, $\\kappa$ is the quantum of circulation and $U$ is the solitary wave\nvelocity. It is shown that collapse of a bubble captured by a vortex line leads\nto the generation of such solitary waves in condensates. The various stages of\ncollapse are elucidated. In particularly, it is shown that during collapse the\nvortex core becomes significantly compressed and after collapse two solitary\nwave trains moving in opposite directions are formed on the vortex line."
    },
    {
        "anchor": "Effect of excluded volume interactions on the interfacial properties of\n  colloid-polymer mixtures: We report a numerical study of equilibrium phase-diagrams and interfacial\nproperties of bulk and confined colloid-polymer mixtures using grand canonical\nMonte Carlo simulations. Colloidal particles are treated as hard spheres, while\nthe polymer chains are described as soft repulsive spheres. The\npolymer-polymer, colloid-polymer, and wall-polymer interactions are described\nby density-dependent potentials derived by Bolhuis and Louis [Macromolecules,\n35 (2002), p.1860]. We compared our results with those of the\nAsakura-Oosawa-Vrij model, that treats the polymers as ideal particles. We find\nthat the number of polymers needed to drive the demixing transition is larger\nfor the interacting polymers, and that the gas-liquid interfacial tension is\nsmaller. When the system is confined between two parallel hard plates, we find\ncapillary condensation. Compared with the AOV model, we find that the excluded\nvolume interactions between the polymers suppress capillary condensation. In\norder to induce capillary condensation, smaller undersaturations and smaller\nplate separations are needed in comparison with ideal polymers.",
        "positive": "Mathematics and liquid crystals: A review is given of some mathematical contributions, ideas and questions\nconcerning liquid crystals."
    },
    {
        "anchor": "Percolation in Models of Thin Film Depositions: We have studied the percolation behaviour of deposits for different\n(2+1)-dimensional models of surface layer formation. The mixed model of\ndeposition was used, where particles were deposited selectively according to\nthe random (RD) and ballistic (BD) deposition rules. In the mixed one-component\nmodels with deposition of only conducting particles, the mean height of the\npercolation layer (measured in monolayers) grows continuously from 0.89832 for\nthe pure RD model to 2.605 for the pure RD model, but the percolation\ntransition belong to the same universality class, as in the 2- dimensional\nrandom percolation problem. In two- component models with deposition of\nconducting and isolating particles, the percolation layer height approaches\ninfinity as concentration of the isolating particles becomes higher than some\ncritical value. The crossover from 2d to 3d percolation was observed with\nincrease of the percolation layer height.",
        "positive": "Thermally Activated Dynamics of the Capillary Condensation: This paper is devoted to the thermally activated dynamics of the capillary\ncondensation. We present a simple model which enables us to identify the\ncritical nucleus involved in the transition mechanism. This simple model is\nthen applied to calculate the nucleation barrier from which we can obtain\ninformations on the nucleation time. We present a simple estimation of the\nnucleation barrier in slab geometry both in the two dimensional case and in the\nthree dimensional case. We extend the model in the case of rough surfaces which\nis closer to the experimental case and allows comparison with experimental\ndatas."
    },
    {
        "anchor": "Fluids confined in wedges and by edges: From cluster integrals to\n  thermodynamic properties referred to different regions: Recently, new insights in the relation between the geometry of the vessel\nthat confines a fluid and its thermodynamic properties were traced through the\nstudy of cluster integrals for inhomogeneous fluids. In this work I analyze the\nthermodynamic properties of fluids confined in wedges or by edges, emphasizing\non the question of the region to which these properties refer. In this context,\nthe relations between the line-thermodynamic properties referred to different\nregions are derived as analytic functions of the dihedral angle $\\alpha$ , for\n$0<\\alpha<2\\pi$ , which enables a unified approach to both edges and wedges. As\na simple application of these results, I analyze the properties of the confined\ngas in the low-density regime. Finally, using recent analytic results for the\nsecond cluster integral of the confined hard sphere fluid, the low density\nbehavior of the line thermodynamic properties is analytically studied up to\norder two in the density for $0<\\alpha<2\\pi$ and by adopting different\nreference regions.",
        "positive": "Delayed bifurcation in elastic snap-through instabilities: We study elastic snap-through induced by a control parameter that evolves\ndynamically. In particular, we study an elastic arch subject to an\nend-shortening that evolves linearly with time, i.e. at a constant rate. For\nlarge end-shortening the arch is bistable but, below a critical end-shortening,\nthe arch becomes monostable. We study when and how the arch transitions between\nstates and show that the end-shortening at which the fast 'snap' happens\ndepends on the rate at which the end-shortening is reduced. This lag in\nsnap-through is a consequence of delayed bifurcation and occurs even in the\nperfectly elastic case when viscous (and viscoelastic) effects are negligible.\nWe present the results of numerical simulations to determine the magnitude of\nthis lag as the loading rate and the importance of external viscous damping\nvary. We also present an asymptotic analysis of the geometrically-nonlinear\nproblem that reduces the salient dynamics to that of an ordinary differential\nequation; the form of this reduced equation is generic for snap-through\ninstabilities in which the relevant control parameter is ramped linearly in\ntime. Moreover, this asymptotic reduction allows us to derive analytical\nresults for the observed lag in snap-through that are in good agreement with\nthe numerical results of our simulations. Finally, we discuss scaling laws for\nthe lag that should be expected in other examples of delayed bifurcation in\nelastic instabilities."
    },
    {
        "anchor": "A multiscale Molecular Dynamics approach to Contact Mechanics: The friction and adhesion between elastic bodies are strongly influenced by\nthe roughness of the surfaces in contact. Here we develop a multiscale\nmolecular dynamics approach to contact mechanics, which can be used also when\nthe surfaces have roughness on many different length-scales, e.g., for self\naffine fractal surfaces. As an illustration we consider the contact between\nrandomly rough surfaces, and show that the contact area varies linearly with\nthe load for small load. We also analyze the contact morphology and the\npressure distribution at different magnification, both with and without\nadhesion. The calculations are compared with analytical contact mechanics\nmodels based on continuum mechanics.",
        "positive": "A Generalization of Shell Theorem. Electric Potential of Charged Spheres\n  and Charged Vesicles Surrounded by Electrolyte: By using the Debye screened potential a generalized version of Newton's Shell\nTheorem is developed and analytical equations are derived to calculate i) the\npotential of a charged sphere surrounded by electrolyte, ii) the potential of\ntwo concentric charged spheres surrounded by electrolyte, and iii) the membrane\npotential of a charged lipid vesicle surrounded by electrolyte with high ion\nconcentration. By numerical integration the potential of a lipid vesicle is\ncalculated at any electrolyte concentration."
    },
    {
        "anchor": "Motile bacteria crossing liquid-liquid interfaces: Real-life bacteria often swim in complex fluids, but our understanding of the\ninteractions between bacteria and complex surroundings is still evolving. In\nthis work, rod-like $\\textit{Bacillus subtilis}$ swims in a quasi-2D\nenvironment with aqueous liquid-liquid interfaces, i.e., the isotropic-nematic\ncoexistence phase of an aqueous chromonic liquid crystal. Focusing on the\nbacteria motion near and at the liquid-liquid interfaces, we collect and\nquantify bacterial trajectories from the isotropic to the nematic phase.\nDespite its small magnitude, the interfacial tension of the order of 10\n$\\mathrm{\\mu N/m}$ at the isotropic-nematic interface justifies our\nobservations that bacteria swimming more perpendicular to the interface have a\nhigher probability of crossing the interface. Our force-balance model,\nconsidering the interfacial tension, further predicts how the length and speed\nof the bacteria affect their crossing behaviors.",
        "positive": "Emergence of bimodal motility in active droplets: To explore and react to their environment, living micro-swimmers have\ndeveloped sophisticated strategies for locomotion - in particular, motility\nwith multiple gaits. To understand the physical principles associated with such\na behavioural variability,synthetic model systems capable of mimicking it are\nneeded. Here, we demonstrate bimodal gait switching in autophoretic droplet\nswimmers. This minimal experimental system is isotropic at rest, a symmetry\nthat can be spontaneously broken due to the nonlinear coupling between\nhydrodynamic and chemical fields, inducing a variety of flow patterns that lead\nto different propulsive modes. We report a dynamical transition from\nquasi-ballistic to bimodal chaotic motion, controlled by the viscosity of the\nswimming medium. By simultaneous visualisation of the chemical and hydrodynamic\nfields, supported quantitatively by an advection-diffusion model, we show that\nhigher hydrodynamic modes become excitable with increasing viscosity, while the\nrecurrent mode-switching is driven by the droplet's interaction with\nself-generated chemical gradients. We further demonstrate that this gradient\ninteraction results in anomalous diffusive swimming akin to self-avoiding\nspatial exploration strategies observed in nature."
    },
    {
        "anchor": "On the crystallization Kinetics in Natural Rubber: In this article, we introduce a framework to investigate the growth of\nnano-crystallites in a polymer matrix numerically. This framework combines the\nFlory theory of entropic elasticity with phase-field approaches commonly used\nto model crystal growth. We investigate in particular the growth kinetics of a\ncrystallite in the presence of topological constraints such as entanglements or\ncross-links, and show that depending on the coupling between the topological\nconstraints and the growth kinetics various structures can be observed:\nbranched structures looking like spherulites or stable nano-crystallites as\nobserved in strain-induced crystallization.",
        "positive": "Tangential contacts of three-dimensional power-law graded elastic\n  solids: A general theory and application to partial slip: A rigorous theory for solving tangential contacts between three-dimensional\npower-law graded elastic solids of arbitrary geometry is presented. For\nmultiple contacts such as those occurring between two nominally flat but rough\nhalf-spaces, the well-known Ciavarella-J\\\"ager theorem is established\naccompanied by a discussion of tangential coupling. Nevertheless, the focus of\nthe work is on axisymmetric single contacts under arbitrary unidirectional\ntangential loading, for which closed-form analytical solutions are derived\nbased on the Mossakovskii-J\\\"ager procedure. In comparison to the results of\ncommon approximate methods, the solutions include the non-axisymmetric\ncomponents of tangential displacements, which are indispensable for the\naccurate determination of the relative slip components and thus the surface\ndensity of frictional energy dissipation in the partial slip regime. Although a\nsimplified approach is used for the calculation of the dissipated energy\ndensity, the results in the limiting case of homogeneous material are in\nexcellent agreement with those from a full numerical computation. As an\napplication example, the complete solutions for the tangential contact of\nparabolically shaped power-law graded elastic solids in the partial slip regime\nare derived and the influence of the material gradient as well as Poisson's\nratio on the surface density of dissipated energy is investigated."
    },
    {
        "anchor": "The role of particle shape in active depletion: Using numerical simulations, we study how a solution of small active disks,\nacting as depletants, induces effective interactions on large passive colloids.\nSpecifically, we analyze how the range, strength, and sign of these\ninteractions are crucially dependent on the shape of the colloids. Our findings\nindicate that while colloidal rods experience a long-ranged predominantly\nattractive interaction, colloidal disks feel a purely repulsive force that is\nshort-ranged in nature and grows in strength with the size ratio between the\ncolloids and active depletants. For colloidal rods, simple scaling arguments\nare proposed to characterize the strength of these induced interactions.",
        "positive": "Fluctuation driven height reduction of crosslinked polymer brushes: We study the changes in the conformations of brushes upon the addition of\ncrosslinks between the chains using the bond fluctuation model. The\nFlory-Rehner model applied to uni-axially swollen networks predicts a collapse\nfor large degrees of crosslinking $q$ proportional to $q^{-1/3}$ in\ndisagreement with our simulation data. We show that the height reduction of the\nbrushes is driven by monomer fluctuations in direction perpendicular to the\ngrafting plane and not due to network elasticity. We observe that the impact of\ncrosslinking is different for reactions between monomers of the same or on\ndifferent chains. If the length reduction of the effective chain length due to\nboth types of reactions is accounted for in a function $\\beta(q)$, the height\nof the brush can be derived from a Flory approach for the equilibrium brush\nheight leading to $H(q)\\approx H_{b}\\beta(q)^{1/3}$, whereby $H_{b}$ denotes\nthe height of the non-crosslinked brush."
    },
    {
        "anchor": "Theory and modeling of particles with DNA-mediated interactions: In recent years significant attention has been attracted to proposals which\nutilize DNA for nanotechnological applications. Potential applications of these\nideas range from the programmable self-assembly of colloidal crystals, to\nbiosensors and nanoparticle based drug delivery platforms. In Chapter I we\nintroduce the system, which generically consists of colloidal particles\nfunctionalized with specially designed DNA markers. The sequence of bases on\nthe DNA markers determines the particle type. Due to the hybridization between\ncomplementary single-stranded DNA, specific, type-dependent interactions can be\nintroduced between particles by choosing the appropriate DNA marker sequences.\nIn Chapter II we develop a statistical mechanical description of the\naggregation and melting behavior of particles with DNA-mediated interactions.\nIn Chapter III a model is proposed to describe the dynamical departure and\ndiffusion of particles which form reversible key-lock connections. In Chapter\nIV we propose a method to self-assemble nanoparticle clusters using DNA\nscaffolds. A natural extension is discussed in Chapter V, the programmable\nself-assembly of nanoparticle clusters where the desired cluster geometry is\nencoded using DNA-mediated interactions. In Chapter VI we consider a\nnanoparticle based drug delivery platform for targeted, cell specific\nchemotherapy. In Chapter VII we present prospects for future research: the\nconnection between DNA-mediated colloidal crystallization and jamming, and the\ninverse problem in self-assembly.",
        "positive": "Robust boundary flow in chiral active fluid: We perform experiments on an active chiral fluid system of self-spinning\nrotors in confining boundary. Along the boundary, actively rotating rotors\ncollectively drives a unidirectional material flow. We systematically vary\nrotor density and boundary shape; boundary flow robustly emerges under all\nconditions. Flow strength initially increases then decreases with rotor density\n(quantified by area fraction $\\phi$); peak strength appears around a density\n$\\phi=0.65$. Boundary curvature plays an important role: flow near a concave\nboundary is stronger than that near a flat or convex boundary in the same\nconfinements. Our experimental results in all cases can be reproduced by a\ncontinuum theory with single free fitting parameter, which describes the\nfrictional property of the boundary. Our results support the idea that boundary\nflow in active chiral fluid is topologically protected; such robust flow can be\nused to develop materials with novel functions."
    },
    {
        "anchor": "Mean-field model for Josephson oscillation in a Bose-Einstein condensate\n  on an one-dimensional optical trap: Using the axially-symmetric time-dependent Gross-Pitaevskii equation we study\nthe phase coherence in a repulsive Bose-Einstein condensate (BEC) trapped by a\nharmonic and an one-dimensional optical lattice potential to describe the\nexperiment by Cataliotti {\\it et al.} on atomic Josephson oscillation [Science\n{\\bf 293}, 843 (2001)]. The phase coherence is maintained after the BEC is set\ninto oscillation by a small displacement of the magnetic trap along the optical\nlattice. The phase coherence in the presence of oscillating neutral current\nacross an array of Josephson junctions manifests in an interference pattern\nformed upon free expansion of the BEC. The numerical response of the system to\na large displacement of the magnetic trap is a classical transition from a\ncoherent superfluid to an insulator regime and a subsequent destruction of the\ninterference pattern in agreement with the more recent experiment by Cataliotti\n{\\it et al.} [e-print cond-mat/0207139].",
        "positive": "A Solvable Model for Polymorphic Dynamics of Biofilaments: We investigate an analytically tractable toy model for thermally induced\npolymorphic dynamics of cooperatively rearranging biofilaments - like\nmicrotubules. The proposed 4 -block model, which can be seen as a\ncoarse-grained approximation of the full polymorphic tube model, permits a\ncomplete analytical treatment of all thermodynamic properties including\ncorrelation functions and angular fourier mode distributions. Due to its\nmathematical tractability the model straightforwardly leads to some physical\ninsights in recently discussed phenomena like the \"length dependent persistence\nlength\". We show that a polymorphic filament can disguise itself as a classical\nworm like chain on small and on large scales and yet display distinct anomalous\ntell-tale features indicating an inner switching dynamics on intermediate\nlength scales."
    },
    {
        "anchor": "Bottom-up construction of dynamic density functional theories for\n  inhomogeneous polymer systems from microscopic simulations: We propose and compare different strategies to construct dynamic density\nfunctional theories (DDFTs) for inhomogeneous polymer systems close to\nequilibrium from microscopic simulation trajectories. We focus on the\nsystematic construction of the mobility coefficient, $\\Lambda(r,r')$, which\nrelates the thermodynamic driving force on monomers at position $r'$ to the\nmotion of monomers at position $r$. A first approach based on the Green-Kubo\nformalism turns out to be impractical because of a severe plateau problem.\nInstead, we propose to extract the mobility coefficient from an effective\ncharacteristic relaxation time of the single chain dynamic structure factor. To\ntest our approach, we study the kinetics of ordering and disordering in diblock\ncopolymer melts. The DDFT results are in very good agreement with the data from\ncorresponding fine-grained simulations.",
        "positive": "Tuning colloid-interface interactions by salt partitioning: We show that the interaction of an oil-dispersed colloidal particle with an\noil-water interface is highly tunable from attractive to repulsive, either by\nvarying the sign of the colloidal charge via charge regulation, or by varying\nthe difference in hydrophilicity between the dissolved cations and anions. In\naddition, we investigate the yet unexplored interplay between the\nself-regulated colloidal surface charge distribution with the planar double\nlayer across the oil-water interface and the spherical one around the colloid.\nOur findings explain recent experiments and have direct relevance for tunable\nPickering emulsions."
    },
    {
        "anchor": "Soliton Staircases and Standing Strain Waves in Confined Colloidal\n  Crystals: We show by computer simulation of a two-dimensional crystal confined by\ncorrugated walls that confinement can be used to impose a controllable\nmesoscopic superstructure of predominantly mechanical elastic character. Due to\nan interplay of the particle density of the system and the width D of the\nconfining channel, \"soliton staircases\" can be created along both parallel\nconfining boundaries, that give rise to standing strain waves in the entire\ncrystal. The periodicity of these waves is of the same order as D. This\nmechanism should be useful for structure formation in the self-assembly of\nvarious nanoscopic materials.",
        "positive": "Tuning selective reflection of light by surface anchoring in cholesteric\n  cells with oblique helicoidal structures: Selective reflection of light by oblique helicoidal cholesteric (ChOH) can be\ntuned in a very broad spectral range by an applied electric field. In this\nwork, we demonstrate that the peak wavelength of the selective reflection can\nbe controlled by surface alignment of the director in sandwich cells. The peak\nwavelength is blue-shifted when the surface alignment is perpendicular to the\nbounding plates and red-shifted when it is planar. The effect is explained by\nthe electric field redistribution within the cell caused by spatially varying\nheliconical ChOH structure. The observed phenomenon can be used in sensing\napplications."
    },
    {
        "anchor": "Monte Carlo Simulations of the two-dimensional dipolar fluid: We study a two-dimensional fluid of dipolar hard disks by Monte Carlo\nsimulations in a square with periodic boundary conditions and on the surface of\na sphere. The theory of the dielectric constant and the asymptotic behaviour of\nthe equilibrium pair correlation function in the fluid phase is derived for\nboth geometries. After having established the equivalence of the two methods we\nstudy the stability of the liquid phase in the canonical ensemble. We give\nevidence of a phase made of living polymers at low temperatures and provide a\ntentative phase diagram.",
        "positive": "Direct observation of the phonon energy in a Bose-Einstein condensate by\n  tomographic imaging: The momentum and energy of phonons in a Bose-Einstein condensate are measured\ndirectly from a time-of-flight image by computerized tomography. We find that\nthe same atoms that carry the momentum of the excitation also carry the\nexcitation energy. The measured energy is in agreement with the Bogoliubov\nspectrum. Hydrodynamic simulations are performed which confirm our observation."
    },
    {
        "anchor": "Structure and dynamics of a layer of sedimented Brownian particles: We investigate experimentally and theoretically thin layers of colloid\nparticles held adjacent to a solid substrate by gravity. Epifluorescence,\nconfocal, and holographic microscopy, combined with Monte Carlo and\nhydrodynamic simulations, are applied to infer the height distribution function\nof particles above the surface, and their diffusion coefficient parallel to it.\nAs the particle area fraction is increased, the height distribution becomes\nbimodal, indicating the formation of a distinct second layer. In our theory we\ntreat the suspension as a series of weakly coupled quasi-two-dimensional layers\nin equilibrium with respect to particle exchange. We experimentally,\nnumerically, and theoretically study the changing occupancies of the layers as\nthe area fraction is increased. The decrease of the particle diffusion\ncoefficient with concentration is found to be weakened by the layering. We\ndemonstrate that particle polydispersity strongly affects the properties of the\nsedimented layer, because of particle size segregation due to gravity.",
        "positive": "Escape rate of active particles in the effective equilibrium approach: The escape rate of a Brownian particle over a potential barrier is accurately\ndescribed by the Kramers theory. A quantitative theory explicitly taking the\nactivity of Brownian particles into account has been lacking due to the\ninherently out-of-equilibrium nature of these particles. Using an effective\nequilibrium approach [Farage et al., Phys. Rev. E 91, 042310 (2015)] we study\nthe escape rate of active particles over a potential barrier and compare our\nanalytical results with data from direct numerical simulation of the colored\nnoise Langevin equation. The effective equilibrium approach generates an\neffective potential which, when used as input to Kramers rate theory, provides\nresults in excellent agreement with the simulation data."
    },
    {
        "anchor": "Ultrafiltration modeling of non-ionic microgels: Membrane ultrafiltration (UF) is a pressure driven process allowing for the\nseparation and enrichment of protein solutions and dispersions of nanosized\nmicrogel particles. The permeate flux and the near-membrane\nconcentration-polarization (CP) layer in this process is determined by\nadvective-diffusive dispersion transport and the interplay of applied and\nosmotic transmembrane pressure contributions. The UF performance is thus\nstrongly dependent on the membrane properties, the hydrodynamic structure of\nthe Brownian particles, their direct and hydrodynamic interactions, and the\nboundary conditions. We present a macroscopic description of cross-flow UF of\nnon-ionic microgels modeled as solvent-permeable spheres. Our filtration model\ninvolves recently derived semi-analytic expressions for the\nconcentration-dependent collective diffusion coefficient and viscosity of\npermeable particle dispersions [Riest et al., Soft Matter, 2015, 11, 2821].\nThese expressions have been well tested against computer simulation and\nexperimental results. We analyze the CP layer properties and the permeate flux\nat different operating conditions and discuss various filtration process\nefficiency and cost indicators. Our results show that the proper specification\nof the concentration-dependent transport coefficients is important for reliable\nfiltration process predictions. We also show that the solvent permeability of\nmicrogels is an essential ingredient to the UF modeling. The particle\npermeability lowers the particle concentration at the membrane surface, thus\nincreasing the permeate flux.",
        "positive": "Shape programming lines of concentrated Gaussian curvature: Liquid crystal elastomers (LCEs) can undergo large reversible contractions\nalong their nematic director upon heating or illumination. A spatially\npatterned director within a flat LCE sheet thus encodes a pattern of\ncontraction on heating, which can morph the sheet into a curved shell, akin to\nhow a pattern of growth sculpts a developing organism. Here we consider,\ntheoretically, numerically and experimentally, patterns constructed from\nregions of radial and circular director, which, in isolation, would form cones\nand anticones. The resultant surfaces contain curved ridges with sharp V-shaped\ncross-sections, associated with the boundaries between regions in the patterns.\nSuch ridges may be created in positively and negatively curved variants and,\nsince they bear Gauss curvature (quantified here via the Gauss-Bonnet theorem),\nthey cannot be flattened without energetically prohibitive stretch. Our\nexperiments and numerics highlight that, although such ridges cannot be\nflattened isometrically, they can deform isometrically by trading the\n(singular) curvature of the V angle against the (finite) curvature of the ridge\nline. Furthermore, in finite thickness sheets, the sharp ridges are inevitably\nnon-isometrically blunted to relieve bend, resulting in a modest smearing out\nof the encoded singular Gauss curvature. We close by discussing the use of such\nfeatures as actuating linear features, such as probes, tongues and limbs, and\nhighlighting the similarities between these patterns of shape change and those\nfound during the morphogenesis of several biological systems."
    },
    {
        "anchor": "Novel structure formation of a phase separating colloidal fluid in a\n  ratchet potential: Based on Dynamical Density Functional Theory (DDFT) we investigate a binary\nmixture of interacting Brownian particles driven over a substrate via a\none-dimensional ratchet potential. The particles are modeled as soft spheres\nwhere one component carries a classical Heisenberg spin. In the absence of a\nsubstrate field, the system undergoes a first-order fluid-fluid demixing\ntransition driven by the spin-spin interaction. We demonstrate that the\ninterplay between the intrinsic spinodal decomposition and time-dependent\nexternal forces leads to a novel dynamical instability where stripes against\nthe symmetry of the external potential form. This structural transition is\nobserved for a broad range of parameters related to the ratchet potential.\nMoreover, we find intriguing effects for the particle transport.",
        "positive": "Effect of chain length distribution on mechanical behavior of polymeric\n  networks: The effect of network chain distribution on mechanical behavior of elastomers\nis one of the long standing problems in rubber mechanics. The classical theory\nof rubber elasticity is built upon the assumption of entropic elasticity of\nnetworks whose constitutive strands are of uniform length. The kinetic theories\nfor vulcanization, computer simulations, and indirect experimental measurements\nall indicate that the microstructure of vulcanizates is made of polymer strands\nwith a random distribution of length. The polydispersity in strand length is\nexpected to control the mechanical strength of rubber as the overloaded short\nstrands break at small deformations and transfer the load to the longer\nstrands. The purpose of this contribution is to present a simple theory of\nrubber mechanics which takes into account the length distribution of strands\nand its effect on the onset of bulk failure."
    },
    {
        "anchor": "Shapes of sedimenting soft elastic capsules in a viscous fluid: Soft elastic capsules which are driven through a viscous fluid undergo shape\ndeformation coupled to their motion. We introduce an iterative solution scheme\nwhich couples hydrodynamic boundary integral methods and elastic shape\nequations to find the stationary axisymmetric shape and the velocity of an\nelastic capsule moving in a viscous fluid at low Reynolds numbers. We use this\napproach to systematically study dynamical shape transitions of capsules with\nHookean stretching and bending energies and spherical rest shape sedimenting\nunder the influence of gravity or centrifugal forces. We find three types of\npossible axisymmetric stationary shapes for sedimenting capsules with fixed\nvolume: a pseudospherical state, a pear-shaped state, and buckled shapes.\nCapsule shapes are controlled by two dimensionless parameters, the\nF\\\"oppl-von-K\\'arm\\'an number characterizing the elastic properties and a Bond\nnumber characterizing the driving force. For increasing gravitational force the\nspherical shape transforms into a pear shape. For very large bending rigidity\n(very small F\\\"oppl-von-K\\'arm\\'an number) this transition is discontinuous\nwith shape hysteresis. The corresponding transition line terminates, however,\nin a critical point, such that the discontinuous transition is not present at\ntypical F\\\"oppl-von-K\\'arm\\'an numbers of synthetic capsules. In an additional\nbifurcation, buckled shapes occur upon increasing the gravitational force. This\ntype of instability should be observable for generic synthetic capsules. All\nshape bifurcations can be resolved in the force-velocity relation of\nsedimenting capsules, where up to three capsule shapes with different\nvelocities can occur for the same driving force. All three types of possible\naxisymmetric stationary shapes are stable with respect to rotation during\nsedimentation.",
        "positive": "On the route to shear jamming, are fragile states real?: Starting from an unjammed initial state, applying shear to a granular\nmaterial of a fixed packing fraction below $\\phi_J$, i.e. the isotropic jamming\ndensity of frictionless spheres can produce shear jamming states, as have been\ndiscovered recently. In addition, it has also been discovered that the system\nwill first experience a bulk fragile state before evolving into a shear jammed\nstate. Due to the existence of friction between the system and the third\ndimension in the previous studies, it is unclear whether such fragile state\nwould still exist on the route to shear jamming if the friction with the third\ndimension were completely eliminated and the background noise level were\ngreatly reduced. Using a novel apparatus, we have completely eliminated the\nfriction between particles and the third dimension by floating the particles on\nthe surface of a shallow water layer thus revealing more details of the route\nof shear-jamming. We are able to measure weak boundary pressure of three orders\nof magnitude below the resolution of the photo-elastic method through the\ncombination force-gauges of high sensitivity and a cantilever-like simple-beam\napparatus. In a system with weak cohesion, we have indeed observed the bulk\nfragile states before the shear jamming; in addition, we have also discovered\nthe boundary fragile states and regimes of negligible shear modus compared to\nbulk modulus. Most importantly, we now have a much better understanding of the\nbulk fragile state: its existence requires an auxiliary in some form, e.g. the\nweak cohesion in this experiment. By constructing a way to freely tune down the\ncohesion to more than six orders of magnitude smaller, to our surprise, we have\ndiscovered the complete vanishing of the bulk fragile states, which thus allows\nus to determine the plausible origin of the bulk fragile state."
    },
    {
        "anchor": "Velocity Distribution of a Homogeneously Cooling Granular Gas: In contrast to molecular gases, granular gases are characterized by inelastic\ncollisions and require therefore permanent driving to maintain a constant\nkinetic energy. The kinetic theory of granular gases describes how the average\nvelocity of the particles decreases after the driving is shut off. Moreover it\npredicts that the rescaled particle velocity distribution will approach a\nstationary state with overpopulated high-velocity tails as compared to the\nMaxwell-Boltzmann distribution. While this fundamental theoretical result was\nreproduced by numerical simulations, an experimental confirmation is still\nmissing. Using a microgravity experiment which allows the spatially homogeneous\nexcitation of spheres via magnetic fields, we confirm the theoretically\npredicted exponential decay of the tails of the velocity distribution.",
        "positive": "Geometric and Topological Entropies of Sphere Packing: We present a statistical mechanical description of randomly packed spherical\nparticles, where the average coordination number is treated as a macroscopic\nthermodynamic variable. The overall packing entropy is shown to have two\ncontributions: geometric, reflecting statistical weights of individual\nconfigurations, and topological, which corresponds to the number of\ntopologically distinct states. Both of them are computed in the thermodynamic\nlimit for isostatic packings in 2D and 3D, and the result is further expanded\nto the case of \"floppy\" particle clusters. The theory is directly applicable to\nsticky colloids, and in addition, generalizes concepts of granular and glassy\nconfigurational entropies for the case of non-jammed systems."
    },
    {
        "anchor": "Defect generation and dynamics during quenching in finite size\n  homogeneous ion chains: An equally spaced linear chain of ions provides a test-bed for studying the\ndefect formation in a finite size 1D system. In particular, defect formation\nrelated to topological phase transition from a linear configuration to a\nzig-zag one is of interest here. A semi-empirical expression provides an\nexcellent agreement to the numerical results. The non-adiabatic transition\nbetween the chain and zig-zag topologies for a finite size system of 30 ions\nshows clear distinction from non-uniformly distributed ion chain. Thus the\nunderlying Homogeneous Kibble-Zurek model can be tested in presently accessible\nion trap experiments. Furthermore, our study indicates collective defect\nbehaviour appearing through the correlation length measurements.",
        "positive": "Coarse-Grain Model for Lipid Bilayer Self-Assembly and Dynamics:\n  Multiparticle Collision Description of the Solvent: A mesoscopic coarse-grain model for computationally-efficient simulations of\nbiomembranes is presented. It combines molecular dynamics simulations for the\nlipids, modeled as elastic chains of beads, with multiparticle collision\ndynamics for the solvent. Self-assembly of a membrane from a uniform mixture of\nlipids is observed. Simulations at different temperatures demonstrate that it\nreproduces the gel and liquid phases of lipid bilayers. Investigations of lipid\ndiffusion in different phases reveals a crossover from subdiffusion to normal\ndiffusion at long times. Macroscopic membrane properties, such as stretching\nand bending elastic moduli, are determined directly from the mesoscopic\nsimulations. Velocity correlation functions for membrane flows are determined\nand analyzed."
    },
    {
        "anchor": "Fluid dynamics of dilatant fluid: Dense mixture of granules and liquid often shows a sever shear thickening and\nis called a dilatant fluid. We construct a fluid dynamics model for the\ndilatant fluid by introducing a phenomenological state variable for a local\nstate of dispersed particles. With simple assumptions for an equation of the\nstate variable, we demonstrate that the model can describe basic features of\nthe dilatant fluid such as the stress-shear rate curve that represents\ndiscontinuous severe shear thickening, hysteresis upon changing shear rate,\ninstantaneous hardening upon external impact. Analysis of the model reveals\nthat the shear thickening fluid shows an instability in a shear flow for some\nregime and exhibits {\\it the shear thickening oscillation}, i.e. the\noscillatory shear flow alternating between the thickened and the relaxed\nstates. Results of numerical simulations are presented for one and\ntwo-dimensional systems.",
        "positive": "Microscopic mechanism for cold denaturation: We elucidate the mechanism of cold denaturation through constant-pressure\nsimulations for a model of hydrophobic molecules in an explicit solvent. We\nfind that the temperature dependence of the hydrophobic effect is the driving\nforce/induces/facilitates cold denaturation. The physical mechanism underlying\nthis phenomenon is identified as the destabilization of hydrophobic contact in\nfavor of solvent separated configurations, the same mechanism seen in pressure\ninduced denaturation. A phenomenological explanation proposed for the mechanism\nis suggested as being responsible for cold denaturation in real proteins."
    },
    {
        "anchor": "Universal Scaling of Clustering Instability for Interacting Active\n  Brownian Particles: Clustering is one of the mayor collective phenomena observed in active\nmatter. We study the overdamped motion of interacting active Brownian particles\nin two dimensions. An instability in the pair correlation function causes the\nonset of clustering. This clustering mechanism depends mainly on the\nself-propulsion properties of the active particles and details of the\ninteractions do not effect the scaling of the clustering instability.\nTheoretical predictions from repeated ring-kinetic theory are confirmed by\nagent-based simulations.",
        "positive": "Pattern Switching and Polarizability for Colloids in Optical Trap Arrays: We show that colloidal molecular crystal states interacting with a periodic\nsubstrate, such as an optical trap array, and a rotating external field can\nundergo a rapid pattern switching in which the orientation of the crystal\nchanges. In some cases, a martensitic-like symmetry switching occurs. It is\nalso possible to create a polarized state where the colloids in each substrate\nminima develop a director field which smoothly rotates with the external drive,\nsimilar to liquid crystal behavior. These results open the possibility for\ncreating novel types of devices using photonic band gap materials, and should\nbe generalizable to a variety of other condensed matter systems with multiple\nparticle trapping."
    },
    {
        "anchor": "On undrained test using Rowe's relation and Incremental Modelling:\n  Generalisation of the notion of Characteristic State: It is recalled that stress-strain incremental modelling is a common feature\nof most theoretical description of the mechanical behaviour of granular\nmaterial. An other commonly accepted characteristics of the mechanical\nbehaviour of granular material is the Rowe's relation which links the dilatancy\nK to the ratio B of vertical-to-lateral stress during a test at constant\nlateral stress, i.e. B =(1+M)(1+K). Using an incremental modelling, this law\nshall be interpreted as a pseudo-Poisson coefficient. We combine these two\nfeatures to solve the problem of an axial compression under undrained\ncondition. We demonstrate that the sample is submitted to a bifurcation of the\ntranscritical type when it reaches the q=Mp line. This allows extending the\nnotion of the characteristic state introduced by Luong to other situations and\nto anisotropic systems. We show also that these undrained tests are quite\nappropriate to study the characteristic-state behaviour.",
        "positive": "Diffusio-phoretic fast swelling of chemically responsive hydrogels: Acid-induced release of stored ions from polyacrylic acid hydrogels (with a\nfree surface fully permeable to the ion and acid flux) was observed to increase\nthe gel osmotic pressure that leads to rapid, temporary swelling faster than\nthe characteristic solvent absorption rate of the gel. Here we develop a\ncontinuum poroelastic theory that quantitatively explains the experiments by\nintroducing a \"gel diffusio-phoresis\" mechanism: Steric repulsion between the\ngel polymers and released ions can induce a diffusio-osmotic solvent intake\ncounteracted by the diffusio-phoretic expansion of the gel network. For\napplications ranging from drug delivery to soft robotics, engineering the gel\ndiffusio-phoresis may enable stimuli-responsive hydrogels with amplified strain\nrates and power output."
    },
    {
        "anchor": "Competing Active and Passive Interactions Drive Amoeba-like Living\n  Crystallites and Ordered Bands: Swimmers and self-propelled particles are physical models for the collective\nbehaviour and motility of a wide variety of living systems, such as bacteria\ncolonies, bird flocks and fish schools. Such artificial active materials are\namenable to physical models which reveal the microscopic mechanisms underlying\nthe collective behaviour. Here we study colloids in a DC electric field. Our\nquasi-two-dimensional system of electrically-driven particles exhibits a rich\nand exotic phase behaviour. At low field strengths, electrohydrodynamic flows\nlead to self-organisation into crystallites with hexagonal order. Upon\nself-propulsion of the particles due to Quincke rotation, we find an ordered\nphase of active matter in which the motile crystallites constantly change shape\nand collide with one another. At higher field strengths, this \"dissolves\" to an\nactive gas. We parameterise a particulate simulation model which reproduces the\nexperimentally observed phases and, at higher field strengths predicts an\nactivity-driven demixing to band-like structures.",
        "positive": "Transport properties controlled by a thermostat: An extended dissipative\n  particle dynamics thermostat: We introduce a variation of the dissipative particle dynamics (DPD)\nthermostat that allows for controlling transport properties of molecular\nfluids. The standard DPD thermostat acts only on a relative velocity along the\ninteratomic axis. Our extension includes the damping of the perpendicular\ncomponents of the relative velocity, yet keeping the advantages of conserving\nGalilei invariance and within our error bar also hydrodynamics. This leads to a\nsecond friction parameter for tuning the transport properties of the system.\nNumerical simulations of a simple Lennard-Jones fluid and liquid water\ndemonstrate a very sensitive behaviour of the transport properties, e.g.,\nviscosity, on the strength of the new friction parameter. We envisage that the\nnew thermostat will be very useful for the coarse-grained and adaptive\nresolution simulations of soft matter, where the diffusion constants and\nviscosity of the coarse-grained models are typically too high/low,\nrespectively, compared to all-atom simulations."
    },
    {
        "anchor": "Generalized single-parameter aging tests and their application to\n  glycerol: Physical aging of glycerol following temperature jumps is studied by\ndielectric spectroscopy at temperatures just below the glass transition\ntemperature. The data are analyzed using two single-parameter aging tests\ndeveloped by Hecksher et al. [J. Chem. Phys. 142, 241103 (2015)]. We generalize\nthese tests to include jumps ending at different temperatures. Moreover, four\ntimes larger jumps than previously are studied. The single-parameter aging\ntests are here for the first time applied to a hydrogen-bonded liquid. We\nconclude that glycerol obeys single-parameter aging to a good approximation.",
        "positive": "Metastability and nucleation in the dilute fluid phase of a simple model\n  of globular proteins: The dilute fluid phase of model globular proteins is studied. The model\npossesses a fluid-fluid transition buried within the fluid-crystal coexistence\nregion, as do some globular proteins. If this fluid-fluid transition is not\nburied deep inside the fluid-crystal coexistence region the crystalline phase\ndoes not nucleate within the dilute fluid. We link this lack of nucleation of\nthe crystal to the interactions in our model and speculate that similar\ninteractions between globular proteins are responsible for the difficulty found\nin crystallising many globular proteins."
    },
    {
        "anchor": "Anisotropic Isometric Fluctuation Relations in experiment and theory on\n  a self-propelled rod: The Isometric Fluctuation Relation (IFR) [P.I. Hurtado et al., PNAS 108, 7704\n(2011)] relates the relative probability of current fluctuations of fixed\nmagnitude in different spatial directions. We test its validity in an\nexperiment on a tapered rod, rendered motile by vertical vibration and immersed\nin a sea of spherical beads. We analyse the statistics of the velocity vector\nof the rod and show that they depart significantly from the IFR of Hurtado et\nal. Aided by a Langevin-equation model we show that our measurements are\nlargely described by an anisotropic generalization of the IFR [R. Villavicencio\net al., EPL 105, 30009 (2014)], with no fitting parameters, but with a\ndiscrepancy in the prefactor whose origin may lie in the detailed statistics of\nthe microscopic noise. The experimentally determined Large-Deviation Function\nof the velocity vector has a kink on a curve in the plane.",
        "positive": "Chemical logic gates on active colloids: Synthetic active colloidal systems are being studied extensively because of\nthe diverse and often unusual phenomena these nonequilibrium systems manifest,\nand their potential applications in fields ranging from biology to material\nscience. Recent studies have shown that active colloidal motors that use\nenzymatic reactions for propulsion hold special promise for applications that\nrequire motors to carry out active sensing tasks in complicated biomedical\nenvironments. In such applications it would be desirable to have active\ncolloids with some capability of computation so that they could act\nautonomously to sense their surroundings and alter their own dynamics to\nperform specific tasks. Here we describe how small chemical networks that make\nuse of enzymatic chemical reactions on the colloid surface can be used to\nconstruct motor-based chemical logic gates. Some basic features of coupled\nenzymatic reactions that are responsible for propulsion and underlie the\nconstruction and function of chemical gates are described using continuum\ntheory and molecular simulation. Examples are given that show how colloids with\nspecific chemical logic gates can perform simple sensing tasks. Due to the\ndiverse functions of different enzyme gates, operating alone or in circuits,\nthe work presented here supports the suggestion that synthetic motors using\nsuch gates could be designed to operate in an autonomous way in order to\ncomplete complicated tasks."
    },
    {
        "anchor": "Structured viscoelastic substrates as linear foundations: The linear (Winkler) foundation is a simple model widely used for decades to\naccount for the surface response of elastic bodies. It models the response as\npurely local, linear, and perpendicular to the surface. We extend this model to\nthe case where the foundation is made of a structured material such as a\npolymer network, which has characteristic scales of length and time. We use the\ntwo-fluid model of viscoelastic structured materials to treat a film of finite\nthickness, supported on a rigid solid and subjected to a concentrated normal\nforce at its free surface. We obtain the foundation modulus (Winkler constant)\nas a function of the film's thickness, intrinsic correlation length, and\nviscoelastic moduli, for three choices of boundary conditions. The results can\nbe used to readily extend earlier applications of the Winkler model to more\ncomplex, microstructured substrates. They also provide a way to extract the\nintrinsic properties of such complex materials from mechanical surface\nmeasurements.",
        "positive": "High-bandwidth viscoelastic properties of aging colloidal glasses and\n  gels: We report measurements of the frequency-dependent shear moduli of aging\ncolloidal systems that evolve from a purely low-viscosity liquid to a\npredominantly elastic glass or gel. Using microrheology, we measure the local\ncomplex shear modulus $G^{*}(\\omega)$ over a very wide range of frequencies (1\nHz- 100 kHz). The combined use of one- and two-particle microrheology allows us\nto differentiate between colloidal glasses and gels - the glass is homogenous,\nwhereas the colloidal gel shows a considerable degree of heterogeneity on\nlength scales larger than 0.5 micrometer. Despite this characteristic\ndifference, both systems exhibit similar rheological behavior which evolve in\ntime with aging, showing a crossover from a single power-law frequency\ndependence of the viscoelastic modulus to a sum of two power laws. The\ncrossover occurs at a time $t_{0}$, which defines a mechanical transition\npoint. We found that the data acquired during the aging of different samples\ncan be collapsed onto a single master curve by scaling the aging time with\n$t_{0}$. This raises questions about the prior interpretation of two power laws\nin terms of a superposition of an elastic network embedded in a viscoelastic\nbackground.\n  Keywords: Aging, colloidal glass, passive microrheology"
    },
    {
        "anchor": "A review on shear jamming: Jamming is a ubiquitous phenomenon that appears in many soft matter systems,\nincluding granular materials, foams, colloidal suspensions, emulsions,\npolymers, and cells -- when jamming occurs, the system undergoes a transition\nfrom flow-like to solid-like states. Conventionally, the jamming transition\noccurs when the system reaches a threshold jamming density under isotropic\ncompression, but recent studies reveal that jamming can also be induced by\nshear. Shear jamming has attracted much interest in the context of\nnon-equilibrium phase transitions, mechanics and rheology of amorphous\nmaterials. Here we review the phenomenology of shear jamming and its related\nphysics. We first describe basic observations obtained in experiments and\nsimulations, and results from theories. Shear jamming is then demonstrated as a\n\"bridge\" that connects the rheology of athermal soft spheres and thermal hard\nspheres. Based on a generalized jamming phase diagram, a universal description\nis provided for shear jamming in frictionless and frictional systems. We\nfurther review the isostaticity and criticality of the shear jamming\ntransition, and the elasticity of shear jammed solids. The broader relevance of\nshear jamming is discussed, including its relation to other phenomena such as\nshear hardening, dilatancy, fragility, and discrete shear thickening.",
        "positive": "Acoustic Attenuation by Two-dimensional Arrays of Rigid Cylinders: In this Letter, we present a theoretical analysis of the acoustic\ntransmission through two-dimensional arrays of straight rigid cylinders placed\nparallelly in the air. Both periodic and completely random arrangements of the\ncylinders are considered. The results for the sound attenuation through the\nperiodic arrays are shown to be in a remarkable agreement with the reported\nexperimental data. As the arrangement of the cylinders is randomized, the\ntransmission is significantly reduced for a wider range of frequencies. For the\nperiodic arrays, the acoustic band structures are computed by the plane-wave\nexpansion method and are also shown to agree with previous results."
    },
    {
        "anchor": "Dynamically Crowded Solutions of Infinitely Thin Brownian Needles: We study the dynamics of solutions of infinitely thin needles up to densities\ndeep in the semidilute regime by Brownian dynamics simulations. For high\ndensities, these solutions become strongly entangled and the motion of a needle\nis essentially restricted to a one-dimensional sliding in a confining tube\ncomposed of neighboring needles. From the density-dependent behavior of the\norientational and translational diffusion, we extract the long-time transport\ncoefficients and the geometry of the confining tube. The sliding motion within\nthe tube becomes visible in the non-Gaussian parameter of the translational\nmotion as an extended plateau at intermediate times and in the intermediate\nscattering function as an algebraic decay. This transient dynamic arrest is\nalso corroborated by the local exponent of the mean-square displacements\nperpendicular to the needle axis. Moreover, the probability distribution of the\ndisplacements perpendicular to the needle becomes strongly non-Gaussian, rather\nit displays an exponential distribution for large displacements. On the other\nhand, based on the analysis of higher-order correlations of the orientation we\nfind that the rotational motion becomes diffusive again for strong confinement.\nAt coarse-grained time and length scales, the spatiotemporal dynamics of the\nneedle for the high entanglement is captured by a single freely diffusing\nphantom needle with long-time transport coefficients obtained from the needle\nin solution. The time-dependent dynamics of the phantom needle is also assessed\nanalytically in terms of spheroidal wave functions. The dynamic behavior of the\nneedle in solution is found to be identical to needle Lorentz systems, where a\ntracer needle explores a quenched disordered array of other needles.",
        "positive": "Dynamics of DNA translocation through an attractive nanopore: We investigate the dynamics of DNA translocation through a nanopore driven by\nan external force using Langevin dynamics simulations in two dimensions (2D) to\nstudy how the translocation dynamics depend on the details of the DNA\nsequences. We consider a coarse-grained model of DNA built from two bases $A$\nand $C$, having different base-pore interactions, {\\textit e.g.}, a strong\n(weak) attractive force between the pore and the base $A$ ($C$) inside the\npore. From a series of studies on hetero-DNAs with repeat units $A_mC_n$, we\nfind that the translocation time decreases exponentially as a function of the\nvolume fraction $f_C$ of the base $C$. %($\\epsilon_{pC} < \\epsilon_{pA}$). For\nlonger $A$ sequences with $f_C \\le 0.5$, the translocation time strongly\ndepends on the orientation of DNA, namely which base enters the pore first. Our\nstudies clearly demonstrate that for a DNA of certain length $N$ with repeat\nunits $A_mC_n$, the pattern exhibited by the waiting times of the individual\nbases and their periodicity can unambiguously determine the values of $m$, $n$\nand $N$ respectively. Therefore, a prospective experimental realization of this\nphenomenon may lead to fast and efficient sequence detection technic."
    },
    {
        "anchor": "Interfacial Entropic Interactions Tunes Fragility and Dynamic\n  Heterogeneity of Glassy Athermal Polymer Nanocomposite films: Enthalpic interactions at the interface between nanoparticles and matrix\npolymers is known to influence various properties of the resultant polymer\nnanocomposites (PNC). For athermal PNCs, consisting of grafted nanoparticles\nembedded in chemically identical polymers, the role and extent of the interface\nlayer (IL) interactions in determining the properties of the nanocomposites is\nnot very clear. Here, we demonstrate the influence of the interfacial layer\ndynamics on the fragility and dynamical heterogeneity (DH) of athermal and\nglassy PNCs. The IL properties are altered by changing the grafted to matrix\npolymer size ratio, f, which in turn changes the extent of matrix chain\npenetration into the grafted layer. The fragility of PNCs is found to increase\nmonotonically with increasing entropic compatibility, characterized by\nincreasing penetration depth. Contrary to observations in most polymers and\nglass formers, we observe an anti-correlation between the dependence on IL\ndynamics of fragility and DH, quantified by the experimentally estimated\nKohlrausch-Watts-Williams parameter and the non-Gaussian parameter obtained\nfrom simulations.",
        "positive": "Kinematic and volumetric analysis of coupled transmembrane fluxes of\n  binary electrolyte solution components: The paper deals with relationships between the individual transmembrane\nfluxes of binary electrolyte solution components and the experimentally\nmeasurable quantities describing rates of transfer processes, namely, the\nelectric current, the transmembrane volume flow and the rates of concentration\nchanges in the solutions adjacent to the membrane. Also, we collected and\nrigorously defined the kinetic coefficients describing the membrane selective\nand electrokinetic properties. A set of useful relationships between these\ncoefficients is derived. An important specificity of the proposed analysis is\nthat it does not use the Irreversible Thermodynamic approach by analyzing no\nthermodynamic forces that generate the fluxes under consideration. Instead, all\nthe regularities are derived on the basis of conservation and linearity\nreasons. The terminology \"Kinematics of Fluxes\" is proposed for such an\nanalysis on the basis of the analogy with Mechanics where Kinematics deals with\nregularities of motion by considering no mechanic forces. The only\nthermodynamic steps of the analysis relate to the discussion on the partial\nmolar volumes of electrolyte and ions that are the equilibrium thermodynamic\nparameters of the adjacent solutions. These parameters are important for\ninterrelating between the transmembrane fluxes of the solution components and\nthe transmembrane volume flow. The paper contains short literature reviews\nconcerned with the partial molar volumes of electrolyte and ions: the methods\nof measurement, the obtained results and their theoretical interpretations. It\nis concluded from the reviews that the classical theories should be corrected\nto make them applicable for sufficiently concentrated solutions, 1M or higher.\nThe proposed correction is taken into account in the kinematic analysis."
    },
    {
        "anchor": "Strong Casimir-like Forces in Flocking Active Matter: Confining in space the equilibrium fluctuations of statistical systems with\nlong-range correlations is known to result into effective forces on the\nboundaries. Here we demonstrate the occurrence of Casimir-like forces in the\nnon-equilibrium context provided by flocking active matter. In particular, we\nconsider a system of aligning self-propelled particles in two spatial\ndimensions, which are transversally confined by reflecting or partially\nreflecting walls. We show that in the ordered flocking phase this confined\nactive vectorial fluid is characterized by extensive boundary layers, as\nopposed to the finite ones usually observed in confined scalar active matter.\nMoreover, a finite-size,fluctuation-induced contribution to the pressure on the\nwall emerges, which decays slowly and algebraically upon increasing the\ndistance between the walls. We explain our findings, which display a certain\ndegree of universality, within a hydrodynamic description of the density and\nvelocity fields.",
        "positive": "To make a glass - avoid the crystal: Colloidal model systems allow for a flexible tuning of particle sizes,\nparticle spacings and mutual interactions at constant temperature. Colloidal\nsuspensions typically crystallize as soon as the interactions get sufficiently\nstrong and long-ranged. Several strategies have been successfully applied to\navoid crystallization and instead produce colloidal glasses. Most of these\namorphous solids are formed at high particle concentrations. This paper shortly\nreviews experimental attempts to produce amorphous colloidal solids using\nstrategies based on topological, thermodynamic and kinetic considerations. We\ncomplement this overview by introducing a (transient) amorphous solid forming\nin a thoroughly deionized aqueous suspension of highly charged spheres at low\nsalt concentration and very low volume fractions."
    },
    {
        "anchor": "Evaporating microfluidic droplets: A tool to study pathogen viability in\n  bioaerosols: Pathogens in droplets on fomites and aerosols go through extreme\nphysiochemical conditions, such as confinement and osmotic stress, due to\nevaporation. Still, these droplets are the predominant transmission routes of\nmany contagious diseases. The biggest challenge for studying the survival\nmechanisms of pathogens in extreme conditions is closely observing them,\nespecially in aerosols, due to the small droplet sizes, movements, and fast\nevaporative dynamics. To mimic evaporating aerosols and microdroplets, we\nemploy microfluidic emulsion droplets. The presence of oil forms a microdroplet\ncluster with spatially gradient evaporation rates, which helps studying the\nimpact of evaporation and its rate. With Escherichia coli, we show that the\nviability is adversely affected by the evaporation and its rate. Our method can\nmimic bioaerosol evaporation with controlled number of cells inside. In\ngeneral, the droplets can act as microreactors with varying kinetics induced by\ndifferent evaporation rates.",
        "positive": "Dynamic Morphologies and Stability of Droplet Interface Bilayers: We develop a theoretical framework for understanding dynamic morphologies and\nstability of droplet interface bilayers (DIBs), accounting for lipid kinetics\nin the monolayers and bilayer, and droplet evaporation due to imbalance between\nosmotic and Laplace pressures. Our theory quantitatively describes distinct\npathways observed in experiments when DIBs become unstable. We find that when\nthe timescale for lipid desorption is slow compared to droplet evaporation, the\nlipid bilayer will grow and the droplets approach a hemispherical shape. In\ncontrast, when lipid desorption is fast, the bilayer area will shrink and the\ndroplets eventually detach. Our model also suggests there is a critical size\nbelow which DIBs cannot be stable, which may explain experimental difficulties\nin miniaturising the DIB platform."
    },
    {
        "anchor": "A structural approach to relaxation in glassy liquids: When a liquid freezes, a change in the local atomic structure marks the\ntransition to the crystal. When a liquid is cooled to form a glass, however, no\nnoticeable structural change marks the glass transition. Indeed, characteristic\nfeatures of glassy dynamics that appear below an onset temperature, T_0, are\nqualitatively captured by mean field theory, which assumes uniform local\nstructure at all temperatures. Even studies of more realistic systems have\nfound only weak correlations between structure and dynamics. This raises the\nquestion: is structure important to glassy dynamics in three dimensions? Here,\nwe answer this question affirmatively by using machine learning methods to\nidentify a new field, that we call softness, which characterizes local\nstructure and is strongly correlated with rearrangement dynamics. We find that\nthe onset of glassy dynamics at T_0 is marked by the onset of correlations\nbetween softness (i.e. structure) and dynamics. Moreover, we use softness to\nconstruct a simple model of slow glassy relaxation that is in excellent\nagreement with our simulation results, showing that a theory of the evolution\nof softness in time would constitute a theory of glassy dynamics.",
        "positive": "Competing Interactions, the Renormalization Group and the\n  Isotropic-Nematic Phase Transition: We discuss 2D systems with Ising symmetry and competing interactions at\ndifferent scales. In the framework of the Renormalization Group, we study the\neffect of relevant quartic interactions. In addition to the usual constant\ninteraction term, we analyze the effect of quadrupole interactions in the self\nconsistent Hartree approximation. We show that in the case of repulsive\nquadrupole interaction, there is a first order phase transition to a stripe\nphase in agreement with the well known Brazovskii result. However, in the case\nof attractive quadrupole interactions there is an isotropic-nematic second\norder transition with higher critical temperature."
    },
    {
        "anchor": "Shear shock formation in incompressible viscoelastic solids: Experiments have shown that shear waves induced in brain tissue can develop\ninto shock waves, thus providing a possible explanation of deep traumatic brain\ninjuries. Here, we study the formation of shock waves in soft viscoelastic\nsolids subject to an imposed velocity at their boundary. We consider the plane\nshearing motion of a semi-infinite half-space, which corresponds to a spatially\none-dimensional problem. Incompressible soft solids whose behaviour is\ndescribed by the Fung-Simo quasi-linear viscoelasticy theory (QLV) are\nconsidered, where the elastic response is either exponential or polynomial of\nMooney-Rivlin-Yeoh type. Waveform breaking can occur at the blow-up of\nacceleration waves, leading to one sufficient condition for the formation of\nshocks. A slow scale analysis based on a small amplitude parameter yields a\ndamped Burgers-like equation, thus leading to another shock formation\ncondition. Numerical experiments performed using a dedicated finite volume\nscheme show that these estimates have limited accuracy. Their validity is\nrestricted in the elastic limit too, where exact shock formation conditions are\nknown.",
        "positive": "Effects of Counterions on Nano-confined DNA Thin Films: DNA molecules spin-coated on amorphous quartz substrates are shown to form\nstable films. Electron density profiles (EDPs) along the film depth show that\nfilm prepared from aqueous solution of DNA exhibits layering of the molecules\nin three stacks parallel to the substrate whereas film prepared from counterion\nadded solution does not have layering but have smaller thickness and enhanced\nsurface roughness, although both films have 'liquid-like' height-height\ncorrelations. We explain these results by a model of film of a 'liquid'\ncomprising of rod-like molecules where the counterion concentration in the\nliquid determines the rod length."
    },
    {
        "anchor": "Moving frames and compatibility conditions for three-dimensional\n  director fields: The geometry and topology of the region in which a director field is embedded\nimpose limitations on the kind of supported orientational order. These\nlimitations manifest as compatibility conditions that relate the quantities\ndescribing the director field to the geometry of the embedding space. For\nexample, in two dimensions (2D) the splay and bend fields suffice to determine\na director uniquely (up to rigid motions) and must comply with one relation\nlinear in the Gaussian curvature of the embedding manifold. In 3D there are\nadditional local fields describing the director, i.e. fields available to a\nlocal observer residing within the material, and a number of distinct ways to\nyield geometric frustration. So far it was unknown how many such local fields\nare required to uniquely describe a 3D director field, nor what are the\ncompatibility relations they must satisfy. In this work, we address these\nquestions directly. We employ the method of moving frames to show that a\ndirector field is fully determined by five local fields. These fields are shown\nto be related to each other and to the curvature of the embedding space through\nsix differential relations. As an application of our method, we characterize\nall uniform distortion director fields, i.e., directors for which all the local\ncharacterizing fields are constant in space, in manifolds of constant\ncurvature. The classification of such phases has been recently provided for\ndirectors in Euclidean space, where the textures correspond to foliations of\nspace by parallel congruent helices. For non-vanishing curvature, we show that\nthe pure twist phase is the only solution in positively curved space, while in\nthe hyperbolic space uniform distortion fields correspond to foliations of\nspace by (non-necessarily parallel) congruent helices. Further analysis is\nexpected to allow to also construct of new non-uniform director fields.",
        "positive": "Nature of intrinsic relation between Bloch-band tunneling and\n  modulational instability: On examples of Bose-Einstein condensates embedded in two-dimensional optical\nlattices we show that in nonlinear periodic systems modulational instability\nand inter-band tunneling are intrinsically related phenomena. By direct\nnumerical simulations we found that tunneling results in attenuation or\nenhancement of instability. On the other hand, instability results in\nasymmetric nonlinear tunneling. The effect strongly depends on the band gap\nstructure and it is especially significant in the case of the resonant\ntunneling. The symmetry of the coherent structures emerging from the\ninstability reflects the symmetry of both the stable and the unstable states\nbetween which the tunneling occurs. Our results provide an evidence of profound\neffect of the band structure on superfluid-insulator transition."
    },
    {
        "anchor": "Multi-valent Ion Mediated Polyelectrolyte Association and Structure: Polyelectrolytes are commonly used to chelate multi-valent ions in aqueous\nsolutions, playing a critical role in water softening and the prevention of\nmineralization. At sufficient ionic strength, ion-mediated\npolyelectrolyte--polyelectrolyte interactions can precipitate\npolyelectrolyte--ion complexes, a phenomenon known as \"like-charge attraction\".\nWhile the significant influence of small ions on polyelectrolyte solution phase\nbehavior is recognized, the precise molecular mechanisms driving the\ncounterintuitive phenomenon remain largely elusive. In this study, we employ\nall-atom molecular dynamics simulations to investigate the molecular mechanism\nof like-charge attraction between two poly(acrylic acid) (PAA) chains in\nsolution. We find that moderate quantities of Ca$^{2+}$ ions induce attraction\nbetween PAA chains, facilitated by the formation of PAA--Ca$^{2+}$--PAA bridges\nand a significant increase in the coordination of Ca$^{2+}$ ions by the PAA\nchains. At high Ca$^{2+}$ number densities, ion bridges are disfavored due to\nelectrostatic screening, yet the chains are still attracted to each other due\nto solvent-mediated interactions between the chains and their chelated ions.\nThe insights gleaned from this study not only enrich our understanding of the\nintricate mechanism of like-charge attraction between polyanions in solution\nbut also illuminate the influence of multi-valent ions on polyelectrolyte\ninteractions.",
        "positive": "Jammed Particle Configurations and Dynamics in High-Density\n  Lennard-Jones Binary Mixtures in Two Dimensions: We examine the changeover in the particle configurations and the dynamics in\ndense Lennard-Jones binary mixtures composed of small and large particles. By\nvarying the composition at a low temperature, we realize crystal with defects,\npolycrystal with small grains, and glass with various degrees of disorder. In\nparticular, we show configurations where small crystalline regions composed of\nthe majority species are enclosed by percolated amorphous layers composed of\nthe two species. We visualize the dynamics of configuration changes using the\nmethod of bond breakage and following the particle displacements. In quiescent\njammed states, the dynamics is severely slowed down and is highly heterogeneous\nat any compositions. In shear, plastic deformations multiply occur in\nrelatively fragile regions, growing into large-scale shear bands where the\nstrain is highly localized. Such bands appear on short time scales and change\non long time scales with finite life times."
    },
    {
        "anchor": "Cofinement, entropy, and single-particle dynamics of equilibrium\n  hard-sphere mixtures: We use discontinuous molecular dynamics and grand-canonical transition-matrix\nMonte Carlo simulations to explore how confinement between parallel hard walls\nmodifies the relationships between packing fraction, self-diffusivity, partial\nmolar excess entropy, and total excess entropy for binary hard-sphere mixtures.\nTo accomplish this, we introduce an efficient algorithm to calculate partial\nmolar excess entropies from the transition-matrix Monte Carlo simulation data.\nWe find that the species-dependent self-diffusivities of confined fluids are\nvery similar to those of the bulk mixture if compared at the same,\nappropriately defined, packing fraction up to intermediate values, but then\ndeviate negatively from the bulk behavior at higher packing fractions. On the\nother hand, the relationships between self-diffusivity and partial molar excess\nentropy (or total excess entropy) observed in the bulk fluid are preserved\nunder confinement even at relatively high packing fractions and for different\nmixture compositions. This suggests that the partial molar excess entropy,\ncalculable from classical density functional theories of inhomogeneous fluids,\ncan be used to predict some of the nontrivial dynamical behaviors of fluid\nmixtures in confined environments.",
        "positive": "Active Brownian particles at interfaces: An effective equilibrium\n  approach: A simple theoretical approach is used to investigate active colloids at the\nfree interface and near repulsive substrates. We employ dynamical density\nfunctional theory to determine the steady-state density profiles in an\neffective equilibrium system [Farage et al., Phys. Rev. E, 91 (2015) 042310].\nIn addition to the known accumulation at surfaces, we predict wetting and\ndrying transitions at a flat repulsive wall and capillary condensation and\nevaporation in a slit pore. These new phenomena are closely related to the\nmotility-induced phase separation (MIPS) in the bulk."
    },
    {
        "anchor": "Scaling theory of critical strain-stiffening in disordered elastic\n  networks: Disordered elastic networks provide a framework for describing a wide variety\nof physical systems, ranging from amorphous solids, through polymeric fibrous\nmaterials to confluent cell tissues. In many cases, such networks feature two\nwidely separated rigidity scales and are nearly floppy, yet they undergo a\ndramatic stiffening transition when driven to sufficiently large strains. We\npresent a complete scaling theory of the critical strain-stiffened state in\nterms of the small ratio between the rigidity scales, which is conceptualized\nin the framework of a singular perturbation theory. The critical state features\nquartic anharmonicity, from which a set of nonlinear scaling relations is\nderived. Scaling predictions for the macroscopic elastic modulus beyond the\ncritical state are derived as well, revealing a previously unidentified\ncharacteristic strain scale. The predictions are quantitatively compared to a\nbroad range of available numerical data on biopolymer network models and future\nresearch questions are discussed.",
        "positive": "Solitons and thermal fluctuations in strongly nonlinear solids: We study a chain of anharmonic springs with tunable power law interactions as\na minimal model to explore the propagation of strongly non-linear solitary wave\nexcitations in a background of thermal fluctuations. By treating the solitary\nwaves as quasi-particles, we derive an effective Langevin equation and obtain\ntheir damping rate and thermal diffusion. These analytical findings compare\nfavorably against numerical results from a Langevin dynamic simulation. In our\nchains composed of two sided non-linear springs, we report the existence of an\nexpansion solitary wave (anti-soliton) in addition to the compressive solitary\nwaves observed for non-cohesive macroscopic particles."
    },
    {
        "anchor": "Zero Field Assembly of Long Magnetic Dipolar Chains in 2D Polymer\n  Nanocomposite Films: The existence of magnetic dipolar nanoparticle chains at zero field has been\npredicted theoretically for decades, but these structures are rarely observed\nexperimentally. A prerequisite is a permanent magnetic moment on the particles\nforming the chain. Here we report on the observation of magnetic dipolar chains\nof spherical iron oxide nanoparticles with a diameter of\n\\SI{12.8}{\\nano\\meter}. The nanoparticles are embedded in an ultrathin polymer\nfilm. Due to the high viscosity of the polymer matrix, the dominating\naggregation mechanism is driven by dipolar interactions. Smaller iron oxide\nnanoparticles (\\SI{9.4}{\\nano\\meter}) show no permanent magnetic moment and do\nnot form chains but compact aggregates. Mixed monolayers of different iron\noxide nanoparticles and polymer at the air-water interface are characterized by\nLangmuir isotherms and in-situ X-ray reflectometry (XRR). The combination of\nthe particles with a polymer leads to a stable polymer nanocomposite film at\nthe air-water interface. XRR experiments show that nanoparticles are immersed\nin a thin polymer matrix of \\SI{3}{\\nano\\meter}. Using atomic force microscopy\n(AFM) on Langmuir-Blodgett films, we measure the lateral distribution of\nparticles in the film. An analysis of single structures within transferred\nfilms results in fractal dimensions that are in excellent agreement with 2D\nsimulations.",
        "positive": "Optimal motility strategies for self-propelled agents to explore porous\n  media: Micro-robots for, e.g., biomedical applications, need to be equipped with\nmotility strategies that enable them to navigate through complex environments.\nInspired by biological microorganisms we recreate motility patterns such as\nrun-and-reverse, run-and-tumble or run-reverse-flick applied to active rod-like\nparticles in silico. We investigate their capability to efficiently explore\ndisordered porous environments with various porosities and mean pore sizes\nranging down to the scale of the active particle. By calculating the effective\ndiffusivity for the different patterns, we can predict the optimal one for each\nporous sample geometry. We find that providing the agent with very basic\nsensing and decision making capabilities yields a motility pattern\noutperforming the biologically inspired patterns for all investigated porous\nsamples."
    },
    {
        "anchor": "Memory of shear flow in soft jammed materials: Cessation of flow in simple yield stress fluids results in a complex stress\nrelaxation process that depends on the preceding flow conditions and leads to\nfinite residual stresses. To assess the microscopic origin of this phenomenon,\nwe combine experiments with largescale computer simulations, exploring the\nbehavior of jammed suspensions of soft repulsive particles. A spatio-temporal\nanalysis of microscopic particle motion and local particle configurations\nreveals two contributions to stress relaxation. One is due to flow induced\naccumulation of elastic stresses in domains of a given size, which effectively\nsets the unbalanced stress configurations that trigger correlated dynamics upon\nflow cessation. This scenario is supported by the observation that the range of\nspatial correlations of quasi-ballistic displacements obtained upon flow\ncessation almost exactly mirrors those obtained during flow. The second\ncontribution results from the particle packing that reorganize to minimize the\nresistance to flow by decreasing the number of locally stiffer configurations.\nRegaining rigidity upon flow cessation then effectively sets the magnitude of\nthe residual stress. Our findings highlight that flow in yield stress fluids\ncan be seen as a training process during which the material stores information\nof the flowing state through the development of domains of correlated particle\ndisplacements and the reorganization of particle packings optimized to sustain\nthe flow. This encoded memory can then be retrieved in flow cessation\nexperiments.",
        "positive": "Umklapp collisions and center of mass oscillation of a trapped Fermi gas: Starting from the the Boltzmann equation, we study the center of mass\noscillation of a harmonically trapped normal Fermi gas in the presence of a\none-dimensional periodic potential. We show that for values of the the Fermi\nenergy above the first Bloch band the center of mass motion is strongly damped\nin the collisional regime due to umklapp processes. This should be contrasted\nwith the behaviour of a superfluid where one instead expects the occurrence of\npersistent Josephson-like oscillations."
    },
    {
        "anchor": "Superelastic stress-strain behavior in ferrogels of different types of\n  magneto-elastic coupling: Colloidal magnetic particles embedded in an elastic polymer matrix constitute\na smart material called ferrogel. It responds to an applied external magnetic\nfield by changes in elastic properties, which can be exploited for various\napplications like dampers, vibration absorbers, or actuators. Under appropriate\nconditions, the stress-strain behavior of a ferrogel can display a fascinating\nfeature: superelasticity, the capability to reversibly deform by a huge amount\nwhile barely altering the applied load. In a previous work, using numerical\nsimulations, we investigated this behavior assuming that the magnetic moments\ncarried by the embedded particles can freely reorient to minimize their\nmagnetic interaction energy. Here, we extend the analysis to ferrogels where\nrestoring torques by the surrounding matrix hinder rotations towards a\nmagnetically favored configuration. For example, the particles can be\nchemically cross-linked into the polymer matrix and the magnetic moments can be\nfixed to the particle axes. We demonstrate that these systems still feature a\nsuperelastic regime. As before, the nonlinear stress-strain behavior can be\nreversibly tailored during operation by external magnetic fields. Yet, the\ndifferent coupling of the magnetic moments causes different types of response\nto external stimuli. For instance, an external magnetic field applied parallel\nto the stretching axis hardly affects the superelastic regime but stiffens the\nsystem beyond it. Other smart materials featuring superelasticity, e.g.\nmetallic shape-memory alloys, have already found widespread applications. Our\nsoft polymer systems offer many additional advantages like a typically higher\ndeformability and enhanced biocompatibility combined with high tunability.",
        "positive": "Critical Casimir forces involving a chemically structured substrate: Motivated by recent experiments with confined binary liquid mixtures near\ntheir continous demixing phase transition we study the critical behavior of a\nsystem, which belongs to the Ising universality class, for the film geometry\nwith one planar wall chemically structured such that there is a laterally\nalternating adsorption preference for the species of the binary liquid mixture.\nBy means of Monte Carlo simulations and finite-size scaling analysis we\ndetermine the critical Casimir force and the corresponding universal scaling\nfunction."
    },
    {
        "anchor": "Continuum Nanofluidics: This paper introduces the fundamental continuum theory governing momentum\ntransport in isotropic nanofluidic flows. The theory is an extension to the\nclassical Navier-Stokes equation, which includes coupling between translational\nand rotational degrees of freedom, as well as non-local response functions that\nincorporates spatial correlations. The continuum theory is compared with\nmolecular dynamics simulation data for both relaxation processes and fluid\nflows showing excellent agreement on the nanometer length scale. We also\npresent practical tools to estimate when the extended theory should be used.",
        "positive": "Versatile Capillary Cells for Handling Concentrated Samples in\n  Analytical Ultracentrifugation: In concentrated macromolecular dispersions, far-from-ideal intermolecular\ninteractions determine the dispersion behaviors including phase transition,\ncrystallization, and liquid-liquid phase separation. Here, we present a novel\nversatile capillary-cell design for analytical\nultracentrifugation-sedimentation equilibrium (AUC-SE), ideal for studying\nsamples at high concentrations. Current setups for such studies are difficult\nand unreliable to handle, leading to a low experimental success rate. The\ndesign presented here is easy to use, robust, and reusable for samples in both\naqueous and organic solvents while requiring no special tools or chemical\nmodification of AUC cells. The key and unique feature is the fabrication of\nliquid reservoirs directly on the bottom window of AUC cells, which can be\neasily realized by laser ablation or mechanical drilling. The channel length\nand optical path length are therefore tunable. The success rate for assembling\nthis new cell is close to 100%. We demonstrate the practicality of this cell by\nstudying: 1) the equation of state and second virial coefficients of\nconcentrated gold nanoparticle dispersions in water and bovine serum albumin\n(BSA) as well as lysozyme solution in aqueous buffers, 2) the gelation phase\ntransition of DNA and BSA solutions, and 3) liquid-liquid phase separation of\nconcentrated BSA/polyethylene glycol (PEG) droplets."
    },
    {
        "anchor": "Heterogeneities in Aging Models of Granular Compaction: Kinetically constrained models (KCM) are systems with trivial thermodynamics\nbut often complex dynamical behavior due to constraints on the accessible paths\nfollowed by the system. Exploring these properties, the Kob-Andersen (KA) model\nwas introduced to study the slow dynamics of glass forming liquids and later\nextended to granular materials. In this last context, we present new results on\nthe heterogeneous character of both in and out of equilibrium dynamics, further\nstretching the granular-glass analogy.",
        "positive": "Equilibrium Simulation of the Slip Coefficient in Nanoscale Pores: Accurate prediction of interfacial slip in nanoscale channels is required by\nmany microfluidic applications. Existing hydrodynamic solutions based on\nMaxwellian boundary conditions include an empirical parameter that depends on\nmaterial properties and pore dimensions. This paper presents a derivation of a\nnew expression for the slip coefficient that is not based on the assumptions\nconcerning the details of solid-fluid collisions and whose parameters are\nobtainable from \\textit{equilibrium} simulation. The results for the slip\ncoefficient and flow rates are in good agreement with non-equilibrium molecular\ndynamics simulation."
    },
    {
        "anchor": "Active Inter-cellular Forces in Collective Cell Motility: The collective behaviour of confluent cell sheets is strongly influenced both\nby polar forces, arising through cytoskeletal propulsion and by active\ninter-cellular forces, which are mediated by interactions across cell-cell\njunctions. We use a phase-field model to explore the interplay between these\ntwo contributions and compare the dynamics of a cell sheet when the polarity of\nthe cells aligns to (i) their main axis of elongation, (ii) their velocity, and\n(iii) when the polarity direction executes a persistent random walk.In all\nthree cases, we observe a sharp transition from a jammed state (where cell\nrearrangements are strongly suppressed) to a liquid state (where the cells can\nmove freely relative to each other) when either the polar or the inter-cellular\nforces are increased. In addition, for case (ii) only, we observe an additional\ndynamical state, flocking (solid or liquid), where the majority of the cells\nmove in the same direction. The flocking state is seen for strong polar forces,\nbut is destroyed as the strength of the inter-cellular activity is increased.",
        "positive": "Scaling laws for frictional granular materials confined by constant\n  pressure under oscillatory shear: Herein, we numerically study the rheology of a two-dimensional frictional\ngranular system confined by constant pressure under oscillatory shear. Several\nscaling laws for the storage and loss moduli against the scaled strain\namplitude have been found. The scaling laws in plastic regime for large strain\namplitude can be understood by the angular distributions of the contact force.\nThe scaling exponents are estimated by considering the physical mechanism."
    },
    {
        "anchor": "Critical scaling in linear response of frictionless granular packings\n  near jamming: We study the origin of the scaling behavior in frictionless granular media\nabove the jamming transition by analyzing their linear response. The response\nto local forcing is non-self-averaging and fluctuates over a length scale that\ndiverges at the jamming transition. The response to global forcing becomes\nincreasingly non-affine near the jamming transition. This is due to the\nproximity of floppy modes, the influence of which we characterize by the local\nlinear response. We show that the local response also governs the anomalous\nscaling of elastic constants and contact number.",
        "positive": "A perturbation theory for water with an associating reference fluid: The theoretical description of the thermodynamics of water is challenged by\nthe structural transition towards tetrahedral symmetry at ambient conditions.\nAs perturbation theories typically assume a spherically symmetric reference\nfluid, they are incapable of accurately describing the liquid properties of\nwater at ambient conditions. In this paper we solve this problem, by\nintroducing the concept of an associated reference perturbation theory (APT).\nIn APT we treat the reference fluid as an associating hard sphere fluid which\ntransitions to tetrahedral symmetry in the fully hydrogen bonded limit. We\ncalculate this transition in a theoretically self-consistent manner without\nappealing to molecular simulations. This associated reference provides the\nreference fluid for a second order Barker-Hendersen perturbative treatment of\nthe long-range attractions. We demonstrate that this new approach gives a\nsignificantly improved description of water as compared to standard\nperturbation theories."
    },
    {
        "anchor": "Vibrations of Jammed Disk Packings with Hertzian Interactions: Contact breaking and Hertzian interactions between grains can both give rise\nto nonlinear vibrational response of static granular packings. We perform\nmolecular dynamics simulations at constant energy in 2D of frictionless\nbidisperse disks that interact via Hertzian spring potentials as a function of\nenergy and measure directly the vibrational response from the Fourier transform\nof the velocity autocorrelation function. We compare the measured vibrational\nresponse of static packings near jamming onset to that obtained from the\neigenvalues of the dynamical matrix to determine the temperature above which\nthe linear response breaks down. We compare packings that interact via\nsingle-sided (purely repulsive) and double-sided Hertzian spring interactions\nto disentangle the effects of the shape of the potential from contact breaking.\nOur studies show that while Hertzian interactions lead to weak nonlinearities\nin the vibrational behavior (e.g. the generation of harmonics of the\neigenfrequencies of the dynamical matrix), the vibrational response of static\npackings with Hertzian contact interactions is dominated by contact breaking as\nfound for systems with repulsive linear spring interactions.",
        "positive": "Spatial structure of states of self stress in jammed systems: States of self stress, organizations of internal forces in many-body systems\nthat are in equilibrium with an absence of external forces, can be thought of\nas the constitutive building blocks of the elastic response of a material. In\noverconstrained disordered packings they have a natural mathematical\ncorrespondence with the zero-energy vibrational modes in underconstrained\nsystems. While substantial attention in the literature has been paid to\ndiverging length scales associated with zero- and finite-energy vibrational\nmodes in jammed systems, less is known about the spatial structure of the\nstates of self stress. In this work we define a natural way in which a unique\nstate of self stress can be associated with each bond in a disordered spring\nnetwork derived from a jammed packing, and then investigate the spatial\nstructure of these bond-localized states of self stress. This allows for an\nunderstanding of how the elastic properties of a system would change upon\nchanging the strength or even existence of any bond in the system."
    },
    {
        "anchor": "Shape transformations of toroidal vesicles: Morphologies of genus-1 and 2 toroidal vesicles are studied numerically by\ndynamically triangulated membrane models and experimentally by confocal laser\nmicroscopy. Our simulation results reproduce shape transformations observed in\nour experiments well. At large reduced volumes of the genus-1 vesicles,\nobtained vesicle shapes agree with the previous theoretical prediction, in\nwhich axisymmetric shapes are assumed: double-necked stomatocyte, discoidal\ntoroid, and circular toroid. However, for small reduced volumes, it is revealed\nthat a non-axisymmetric discoidal toroid and handled discocyte exist in thermal\nequilibrium in the parameter range, in which the previous theory predicts\naxisymmetric discoidal shapes. Polygonal toroidal vesicles and subsequent\nbudding transitions are also found. The entropy caused by shape fluctuations\nslightly modifies the stability of the vesicle shapes.",
        "positive": "Scaling regimes of active turbulence with external dissipation: Active fluids exhibit complex turbulent-like flows at low Reynolds number.\nRecent work predicted that 2d active nematic turbulence follows universal\nscaling laws. However, experimentally testing these predictions is conditioned\nby the coupling to the 3d environment. Here, we measure the spectrum of the\nkinetic energy, $E(q)$, in an active nematic film in contact with a passive oil\nlayer. At small and intermediate scales, we find the scaling regimes $E(q)\\sim\nq^{-4}$ and $E(q)\\sim q^{-1}$, respectively, in agreement with the theoretical\nprediction for 2d active nematics. At large scales, however, we find a new\nscaling $E(q)\\sim q$, which emerges when the dissipation is dominated by the 3d\noil layer. In addition, we derive an explicit expression for the spectrum that\nspans all length scales, thus explaining and connecting the different scaling\nregimes. This allows us to fit the data and extract the length scale that\ncontrols the crossover to the new large-scale regime, which we tune by varying\nthe oil viscosity. Overall, our work experimentally demonstrates the emergence\nof universal scaling laws in active turbulence, and it establishes how the\nspectrum is affected by external dissipation."
    },
    {
        "anchor": "Critical volume fraction and critical size for a cluster to nucleate: Combined with the principle of entropy maximum and CS state equation, the\ncritical size for a cluster to nucleate then the critical volume fraction of a\nphase transition is determined in this paper, and our result is in good\nagreement with the experiments. Furthermore, no parameter is introduced in the\ndiscussion.",
        "positive": "Particle-induced transition in foams: The macroscopic behaviour of foams is deeply related to rearrangements\noccurring at the bubble scale, which dynamics depends on the mobility of the\ninterstitial phase. In this paper, we resort to drainage experiments to\nquantify this mobility in particulate foams, where a particle suspension is\nconfined between foam bubbles. Results show a strong dependence on each\ninvestigated parameter, i.e. bubble size, particle size and gas volume fraction\nfor a given particle volume fraction. A combination of these parameters has\nbeen identified as the control parameter \\lambda, which compares the particle\nsize to the size of passage through constrictions within the foam pore space.\n\\lambda\\ highlights a sharp transition: for \\lambda\\ < 1 particles are free to\ndrain with the liquid, which involves the shear of the suspension in foam\ninterstices, for \\lambda\\ > 1 particles are trapped and the mobility of the\ninterstitial phase is strongly reduced."
    },
    {
        "anchor": "Relativistic separable dual-space Gaussian Pseudopotentials from H to Rn: We generalize the concept of separable dual-space Gaussian pseudopotentials\nto the relativistic case. This allows us to construct this type of\npseudopotential for the whole periodic table and we present a complete table of\npseudopotential parameters for all the elements from H to Rn. The relativistic\nversion of this pseudopotential retains all the advantages of its\nnonrelativistic version. It is separable by construction, it is optimal for\nintegration on a real space grid, it is highly accurate and due to its analytic\nform it can be specified by a very small number of parameters. The accuracy of\nthe pseudopotential is illustrated by an extensive series of molecular\ncalculations.",
        "positive": "Anisotropic Elastic Model for Short DNA Loops: Effect of bending anisotropy on a planar DNA loop, using energy minimization\nand neglecting entropic effects, is studied. We show that the anisotropy\nresults in polygonal shape of the loop and increasing the anisotropy makes the\nedges sharper. Calculating the energy of such a loop lets us to find effective\npersistence length as the geometrical mean of hard and soft rigidities, which\nis quite different from harmonic mean for an unconstrained long DNA."
    },
    {
        "anchor": "III. Geometrical framework for thinking about globular proteins: turns\n  in proteins: We have shown recently that the notion of poking pairwise interactions along\na chain provides a unifying framework for understanding the formation of both\nsecondary and the tertiary protein structure based on symmetry and geometry.\n$\\alpha$-helices and $\\beta$-sheets are found to be special geometries that\nhave systematic poking contacts in a repetitive manner with the contacts being\nlocal along the $\\alpha$-helix and non-local along a pair of adjacent strands\nwithin a $\\beta$-sheet. Pairwise poking interactions also govern tertiary\nstructure formation, but they are weaker and there are no special geometrical\nconstraints as in secondary structure formation. Here we demonstrate that\nprotein turns, the most prevalent non-repetitive structural element in\nproteins, are instances of local (as in $\\alpha$-helices) and isolated\n(non-repetitive) poking pairwise contacts for which the geometrical constraints\nare partially relaxed. This simple and purely geometrical definition of protein\nturns (also sometimes known as reverse turns, $\\beta$-turns, $\\beta$-bends,\nhairpin bends, $3_{10}$ bends, kinks, widgets, ...) provides a simple framework\nfor unifying them. We present the results of a systematic analysis and identify\ntheir structural classes as well as their respective amino acid preferences.",
        "positive": "Cross-sectional performance of hollow square prisms with rounded edges: Hollow-section columns are one of the mechanically superior structures with\nhigh buckling resistance and high bending stiffness. The mechanical properties\nof the column are strongly influenced by the cross-sectional shape. Therefore,\nwhen evaluating the stability of a column against external forces, it is\nnecessary to accurately reproduce the cross-sectional shape. In this study, we\npropose a mathematical method to describe a polygonal section with rounded\nedges and vertices. This mathematical model would be quite useful for analyzing\nthe mechanical properties of plants and designing plant-mimicking functional\nstructures, since the cross-sections of the actual plant culms and stems often\nshow rounded polygons."
    },
    {
        "anchor": "Free Cooling Phase-Diagram of Hard-Spheres with Short- and Long-Range\n  Interactions: We study the stability, the clustering and the phase-diagram of free cooling\ngranular gases. The systems consist of mono-disperse particles with additional\nnon-contact (long-range) interactions, and are simulated here by the\nevent-driven molecular dynamics algorithm with discrete (short-range shoulders\nor wells) potentials (in both 2D and 3D). Astonishingly good agreement is found\nwith a mean field theory, where only the energy dissipation term is modified to\naccount for both repulsive or attractive non-contact interactions. Attractive\npotentials enhance cooling and structure formation (clustering), whereas\nrepulsive potentials reduce it, as intuition suggests. The system evolution is\ncontrolled by a single parameter: the non-contact potential strength scaled by\nthe fluctuation kinetic energy (granular temperature). When this is small, as\nexpected, the classical homogeneous cooling state is found. However, if the\neffective dissipation is strong enough, structure formation proceeds, before\n(in the repulsive case) non-contact forces get strong enough to undo the\nclustering (due to the ongoing dissipation of granular temperature). For both\nrepulsive and attractive potentials, in the homogeneous regime, the cooling\nshows a universal behaviour when the (inverse) control parameter is used as\nevolution variable instead of time. The transition to a non-homogeneous regime,\nas predicted by stability analysis, is affected by both dissipation and\npotential strength. This can be cast into a phase diagram where the system\nchanges with time, which leaves open many challenges for future research.",
        "positive": "Crowded Solutions of Single-Chain Nanoparticles under Shear Flow: Single-chain nanoparticles (SCNPs) are ultrasoft objects obtained through\npurely intramolecular cross-linking of single polymer chains. By means of\ncomputer simulations with implemented hydrodynamic interactions, we investigate\nfor the first time the effect of the shear flow on the structural and dynamic\nproperties of SCNPs in semidilute solutions. We characterize the dependence of\nseveral conformational and dynamic observables on the shear rate and the\nconcentration, obtaining a set of power-law scaling laws. The concentration has\na very different effect on the shear rate dependence of the former observables\nin SCNPs than in simple linear chains. Whereas for the latter the scaling\nbehavior is marginally dependent on the concentration, two clearly different\nscaling regimes are found for the SCNPs below and above the overlap\nconcentration. At fixed shear rate SCNPs and linear chains also respond very\ndifferently to crowding. Whereas, at moderate and high Weissenberg numbers the\nlinear chains swell, the SCNPs exhibit a complex non-monotonic behavior. These\nfindings are inherently related to the topological interactions preventing\nconcatenation of the SCNP loops, leading to less interpenetration than for\nlinear chains."
    },
    {
        "anchor": "In silico screening of drug-membrane thermodynamics reveals linear\n  relations between bulk partitioning and the potential of mean force: The partitioning of small molecules in cell membranes---a key parameter for\npharmaceutical applications---typically relies on experimentally-available bulk\npartitioning coefficients. Computer simulations provide a structural resolution\nof the insertion thermodynamics via the potential of mean force, but require\nsignificant sampling at the atomistic level. Here, we introduce high-throughput\ncoarse-grained molecular dynamics simulations to screen thermodynamic\nproperties. This application of physics based models in a large-scale study of\nsmall molecules establishes linear relationships between partitioning\ncoefficients and key features of the potential of mean force. This allows us to\npredict the structure of the insertion from bulk experimental measurements for\nmore than 400,000 compounds. The potential of mean force hereby becomes an\neasily accessible quantity---already recognized for its high predictability of\ncertain properties, e.g., passive permeation. Further, we demonstrate how\ncoarse graining helps reduce the size of chemical space, enabling a\nhierarchical approach to screening small molecules.",
        "positive": "A theory to describe emergent properties of composite F-actin and\n  vimentin networks: The synthetic biopolymeric gels demand a great interest as bio-materials to\nmimic many biological scaffolding structures, which can contribute to a better\nunderstanding of the cytoskeleton-like structural building blocks and soft\nnanotechnology. In particular semiflexible F-actin and vimentin intermediate\nfilaments (IF) form complex networks, and are key regulators of cellular\nstiffness. While the mechanics of F-actin networks or IF have already been\ncharacterised, the interaction between this two networks is largely unknown.\nExperimental studies using large deformations rheology show that\nco-polymerisation of F-actin and IF can produce composite networks either\nstronger or weaker than pure F-actin networks. We theoretically verify these\neffects developing a model into the framework of nonlinear continuum mechanics,\nin which we define a free energy functional considering the role of the\nentropic-elastic for semiflexible networks with transient crosslinks and also\nan energetic term to describe the interaction parameter which allows the\ncoupling among the two networks. We validate the theoretical model with\nmeasurements performed performed by Jensen et al. on large deformations\nrheological experiments with different concentrations of actin and vimentin"
    },
    {
        "anchor": "Average outpouring velocity and flow rate of grains discharged from a\n  tilted quasi-2D silo: The flow of granular materials through constricted openings is important in\nmany natural and industrial processes. These complex flows - featuring dense,\ndissipative flow in the bulk but low-dissipation, low density outpouring in the\nvicinity of the orifice - have long been characterized empirically by the\nBeverloo rule and, recently, modeled successfully using energy balance. The\ndependence of flow rate on the silo's angle with respect to gravity, however,\nis not captured by current models. We experimentally investigate the role of\ntilt angle in this work using a quasi-2D monolayer of grains in a silo. We\nmeasure mass flow rate, the average exit velocities of grains, and the packing\nfraction along the orifice with varying tilt angles. We propose a model that\ndescribes our results (and earlier findings with 3D systems [H. G. Sheldon and\nD. J. Durian, Granul. Matter 12, 579 (2010)]) by considering the dependence of\noutpouring speed and angle with respect to the orifice angle and, importantly,\nthe angle of stagnant zones adjacent to the orifice. We conclude by posing\nquestions about possible extensions of our model in order to describe spatial\nvariations of exit velocity and density along the orifice cross section.",
        "positive": "Screening of a charged particle by multivalent counterions in salty\n  water: Giant charge inversion: Screening of a macroion such as a charged solid particle, a charged membrane,\ndouble helix DNA or actin by multivalent counterions is considered. Small\ncolloidal particles, charged micelles, short or long polyelectrolytes can play\nthe role of multivalent counterions. Due to strong lateral repulsion at the\nsurface of macroion such multivalent counterions form a strongly correlated\nliquid, with the short range order resembling that of a Wigner crystal. These\ncorrelations create additional binding of multivalent counterions to the\nmacroion surface with binding energy larger than $k_BT$. As a result even for a\nmoderate concentration of multivalent counterions in the solution, their total\ncharge at the surface of macroion exceeds the bare macroion charge in absolute\nvalue. Therefore, the net charge of the macroion inverts its sign. In the\npresence of a high concentration of monovalent salt the absolute value of\ninverted charge can be larger than the bare one. This giant inversion of charge\ncan be observed by electrophoresis or by direct counting of multivalent\ncounterions."
    },
    {
        "anchor": "Structured randomness: Jamming of soft discs and pins: Simulations are used to find the zero temperature jamming threshold,\n$\\phi_j$, for soft, bidisperse disks in the presence of small fixed particles,\nor \"pins\", arranged in a lattice. The presence of pins leads, as one expects,\nto a decrease in $\\phi_j$. Structural properties of the system near the jamming\nthreshold are calculated as a function of the pin density. While the\ncorrelation length exponent remains $\\nu = 1/2$ at low pin densities, the\nsystem is mechanically stable with more bonds, yet fewer contacts than the\nMaxwell criterion implies in the absence of pins. In addition, as pin density\nincreases, novel bond orientational order and long-range spatial order appear,\nwhich are correlated with the square symmetry of the pin lattice.",
        "positive": "Absorbing-state transitions in granular materials close to jamming: We consider a model for driven particulate matter in which absorbing states\ncan be reached both by particle isolation and by particle caging. The model\npredicts a non-equilibrium phase diagram in which analogues of hydrodynamic and\nelastic reversibility emerge at low and high volume fractions respectively,\npartially separated by a diffusive, non-absorbing region. We thus find a single\nphase boundary that spans the onset of chaos in sheared suspensions to the\nonset of yielding in jammed packings. This boundary has the properties of a\nnon-equilibrium second order phase transition, leading us to write a Manna-like\nmean-field description that captures the model predictions. Dependent on\ncontact details, jamming marks either a direct transition between the two\nabsorbing states, or occurs within the diffusive region."
    },
    {
        "anchor": "Adhesion-Induced Lateral Phase Separation in Membranes: Adhesion between membranes is studied using a phenomenological model, where\nthe inter-membrane distance is coupled to the concentration of sticker\nmolecules on the membranes. The model applies to both for adhesion of two\nflexible membranes and to adhesion of one flexible membrane onto a second\nmembrane supported on a solid substrate. We mainly consider the case where the\nsticker molecules form bridges and adhere directly to both membranes. The\ncalculated mean-field phase diagrams show an upward shift of the transition\ntemperature indicating that the lateral phase separation in the membrane is\nenhanced due to the coupling effect. Hence the possibility of adhesion-induced\nlateral phase separation is predicted. For a particular choice of the\nparameters, the model exhibits a tricritical behavior. We also discuss the\nnon-monotonous shape of the inter-membrane distance occurring when the lateral\nphase separation takes place. The inter-membrane distance relaxes to the bulk\nvalues with two symmetric overshoots. Adhesion mediated by other types of\nstickers is also considered.",
        "positive": "Microscopic theory for interface fluctuations in binary liquid mixtures: Thermally excited capillary waves at fluid interfaces in binary liquid\nmixtures exhibit simultaneously both density and composition fluctuations.\nBased on a density functional theory for inhomogeneous binary liquid mixtures\nwe derive an effective wavelength dependent Hamiltonian for fluid interfaces in\nthese systems beyond the standard capillary-wave model. Explicit expressions\nare obtained for the surface tension, the bending rigidities, and the coupling\nconstants of compositional capillary waves in terms of the profiles of the two\nnumber densities characterizing the mixture. These results lead to predictions\nfor grazing-incidence x-ray scattering experiments at such interfaces."
    },
    {
        "anchor": "Multi-objective analysis of the Sand Hypoplasticity model calibration: The Sand Hypoplastic (SH) constitutive law by von Wolffersdorff (1996) is a\ninteresting hypoplastic model for soil mechanics. This model includes eight\nparameters, usually calibrated using the oedometric (OE) and the drained\nisotropically consolidated triaxial tests (CD). However, previous studies show\nthat the SH model calibration in the CD test has conflicting requirements in\npredicting the evolution of stresses and strains.\n  In this work, we study the SH model calibration over a wide range of testing\nconditions using 12 OE and 25 CD tests by Wichtmann and Triantafyllidis (2016)\non the Karlsruhe sands. The parameter space is extensively explored via Genetic\nAlgorithm Optimization (GA) using the recently developed open-source software\nGA-cal (available at \\url{https://github.com/FraJoMen/GA-cal}). This\nexploration allowed us to study the SH model's predictive limits and to\nidentify, using a multi-objective analysis, the main parameters governing the\ncompromise between the accurate prediction of stresses versus strain in the CD\ntests.",
        "positive": "Morphological Transformations of Diblock Copolymers in Binary Solvents:\n  A Simulation Study: Morphological transformations of amphiphilic AB diblock copolymers in\nmixtures of a common solvent (S1) and a selective solvent (S2) for the B block\nare studied using the simulated annealing method. We focus on the morphological\ntransformation depending on the fraction of the selective solvent CS2, the\nconcentration of the polymer CP, and the polymer-solvent interactions\n{\\epsilon}ij (i = A, B; j = S1, S2). Morphology diagrams are constructed as\nfunctions of CP, CS2, and/or {\\epsilon}AS2. The copolymer morphological\nsequence from dissolved -> sphere -> rod-> ring/cage-> vesicle is obtained upon\nincreasing CS2 at a fixed CP. This morphology sequence is consistent with\nprevious experimental observations. It is found that the selectivity of the\nselective solvent affects the self-assembled microstructure significantly. In\nparticular, when the interaction {\\epsilon}BS2 is negative, aggregates of\nstacked lamellae dominate the diagram. The mechanisms of aggregate\ntransformation and the formation of stacked lamellar aggregates are discussed\nby analyzing variations of the average contact numbers of the A or B monomers\nwith monomers and with molecules of the two types of solvent, as well as the\nmean square end-to-end distances of chains. It is found that the basic\nmorphological sequence of spheres to rods to vesicles and the stacked lamellar\naggregates result from competition between the interfacial energy and the chain\nconformational entropy. Analysis of the vesicle structure reveals that the\nvesicle size increases with increasing CP or with decreasing CS2, but remains\nalmost unchanged with variations in {\\epsilon}AS2."
    },
    {
        "anchor": "Escape Kinetics of an Underdamped Colloidal Particle from a Cavity\n  through Narrow Pores: It is often desirable to know the controlling mechanism of survival\nprobability of nano - or microscale particles in small cavities such as, e.g.,\nconfined submicron particles in fiber beds of high-efficiency filter media or\nions/small molecules in confined cellular structures. Here we address this\nissue based on numerical study of the escape kinetics of inertial Brownian\ncolloidal particles from various types of cavities with single and multiple\npores. We consider both the situations of strong and weak viscous damping. Our\nsimulation results show that as long as the thermal length is larger than the\ncavity size the mean exit time remains insensitive to the medium viscous\ndamping. On further increasing damping strength, a linear relation between\nescape rate and damping strength emerges gradually. This result is in sharp\ncontrast to the energy barrier crossing dynamics where the escape rate exhibits\na turnover behavior as a function of the damping strength. Moreover, in the\nballistic regime, the exit rate is directly proportional to the pore width and\nthe thermal velocity. All these attributes are insensitive to the cavity as\nwell as the pore structures. Further, we show that the effects of pore\nstructure variation on the escape kinetics are conspicuously different in the\nlow damping regimes compared to the overdamped situation. Apart from direct\napplications in biology and nanotechnology, our simulation results can\npotentially be used to understand diffusion of living or artificial micro/nano\nobjects, such as bacteria, virus, Janus Particle etc. where memory effects play\ndictating roles.",
        "positive": "Analysis of stability of macromolecular clusters in dilute heteropolymer\n  solutions: We study the formation of clusters consisting of several chains in dilute\nsolutions of amphiphilic heteropolymers. By means of the Gaussian variational\ntheory we show that in a region of the phase diagram within the conventional\ntwo-phase coexistence region mesoglobules of equal size possess the lowest free\nenergy. Monte Carlo simulation confirms that the mesoglobules are stabilised\ndue to micro-phase separation, which introduces a preferred length scale. The\nvery existence of such mesoscopic structures is related to a delicate balance\nof the energetic and entropic terms under the connectivity constraints. The\nissue of size monodispersity and fluctuations for mesoglobules is investigated."
    },
    {
        "anchor": "Dynamic heterogeneity in a glass forming fluid: susceptibility,\n  structure factor and correlation length: We investigate the growth of dynamic heterogeneity in a glassy hard-sphere\nmixture for volume fractions up to and including the mode-coupling transition.\nWe use an 80 000 particle system to test a new procedure to evaluate a dynamic\ncorrelation length xi(t): we determine the ensemble independent dynamic\nsusceptibility chi_4(t) and use it to facilitate evaluation of xi(t) from the\nsmall wave vector behavior of the four-point structure factor. We analyze\nrelations between the alpha relaxation time tau_alpha, chi_4(tau_alpha), and\nxi(tau_alpha). We find that mode-coupling like power laws provide a reasonable\ndescription of the data over a restricted range of volume fractions, but the\npower laws' exponents differ from those predicted by the inhomogeneous\nmode-coupling theory. We find xi(tau_alpha) ~ ln(tau_alpha) over the full range\nof volume fractions studied, which is consistent with Adams-Gibbs-type\nrelation.",
        "positive": "A Novel Landau-de Gennes Model with Quartic Elastic Terms: Within the framework of the generalized Landau-de Gennes theory, we identify\na $Q$-tensor-based energy that reduces to the four-constant Oseen-Frank energy\nwhen it is considered over orientable uniaxial nematic states. Although the\ncommonly considered version of the Landau-de Gennes theory has an elastic\ncontribution that is at most cubic in components of the $Q$-tensor and their\nderivatives, the alternative offered here is quartic in these variables. One\nclear advantage of our approach over the cubic theory is that the associated\nminimization problem is well-posed for a significantly wider choice of elastic\nconstants. In particular, quartic energy can be used to model\nnematic-to-isotropic phase transitions for highly disparate elastic constants.\n  In addition to proving well-posedness of the proposed version of the\nLandau-de Gennes theory, we establish a rigorous connection between this theory\nand its Oseen-Frank counterpart via a $\\Gamma$-convergence argument in the\nlimit of vanishing nematic correlation length. We also prove strong convergence\nof the associated minimizers."
    },
    {
        "anchor": "A constitutive model for elastomers tailored by ionic bonds and\n  entanglements: Over the past decade or two, the concept has emerged of using multiple types\nof weak interactions simultaneously to enhance the mechanical properties of\nelastomers. These weak interactions include physical entanglements, hydrogen\nbonds, metal-coordination bonds, dynamic covalent bonds, and ionic bonds. The\ncombination of entanglements and ionic bonding has been minimally explored and\nis particularly exciting because of the broad application space for\npolyelectrolytes. In this work, a constitutive model framework is developed to\ndescribe the response of elastomers with both ionic bonds and entanglements. We\nformulate a micromechanical model that couples together chain stretching, ionic\nbond slipping, and entanglement evolution. The ionic bonds provide toughness by\nenabling plastic deformation in comparison to covalently crosslinked material\nand add strength compared to a linear polymer. Evolution of the entanglement\ndensity is taken as a key mechanism that can govern stiffness, toughness, and\nself-recovery in elastomers. The model is used to match bulk polyelectrolytes\nwith different fractions of ionic components under a variety of loading\nhistories. The variations in material parameters are then used to help\nunderstand the relative importance of different governing mechanisms in the\nbulk polymers. We show that the theoretical framework can explain our\nexperimental uniaxial tensile experimental results for polyelectrolytes. This\nmodel can help to design better material with high stiffness and toughness. We\nexpect that our model can be extended to explain the mechanical behavior of\nother polyelectrolytes and other soft materials with a wide range of dynamic\nbonds.",
        "positive": "Correlated disorder in a well relaxed model binary glass through a local\n  SU(2) bonding topology: A quantitative understanding of the microscopic constraints which underlie a\nwell relaxed glassy structure is the key to developing a microscopic theory of\nstructural evolution and plasticity for the amorphous solid. Here we\ndemonstrate the applicability of one such theory of local bonding constraints\ndeveloped by D. R. Nelson [Phys. Rev. B 28, 5515 (1983)], for a model binary\nLennard-Jones glass structure that has undergone an isothermal annealing\nsimulation spanning over 10 micro-seconds of physical simulation time. By\nintroducing a modified radical Voronoi tessellation which removes some\nambiguity in how nearest neighbour bonds are enumerated, it is found, that a\nlarge proportion ($>95\\%$) of local atomic environments follow the connectivity\nrules of the SU(2) topology of Nelson's work resulting in a dense network of\ndisclination lines characterizing the defect bonds. Furthermore, it is\nnumerically shown that a low energy glass structure corresponds to a reduced\nlevel of bond-length frustration and thus a minimally defected bond-defect\nnetwork. It is then demonstrated that such a defect network provides a\nframework in which to analyse thermally-activated structural excitations,\nrevealing those high-energy/low-density regions not following the connectivity\nconstraints are more likely to undergo structural rearrangement that often\nresults in a local relaxation that ends with the creation of new SU(2) local\ntopology content."
    },
    {
        "anchor": "Self-organized Nano-lens Arrays by Intensified Dewetting of Electron\n  Beam Modified Polymer Thin-films: Sub-100 nm polymeric spherical plano-convex nano-lens arrays are fabricated\nusing short electron beam exposures to selectively modify the ultrathin (< 30\nnm) polymer films, followed by their intensified self-organized dewetting under\nan aqueous-organic mixture. A short exposure to e-beam locally modifies the\npolymer chains to effectively change the viscosity of the film in small\ndomains, thus bringing in the dynamical dewetting contrast in the film that\nproduces aligned and ordered dewetted nanostructures. Both negative and\npositive e-beam tone polymers are thus used to produce array of nano-lenses.\nThe intensified self-organized dewetting under a water-organic solvent mixture\novercomes the limitations on surface tension and dewetting force and thus\nfacilitates the formation of sub-100 nm diameter polymer nanolenses of tunable\ncurvature. By varying the extent of e-beam exposure, various configurations\nfrom isolated to connected nano-lens arrays can be fabricated.",
        "positive": "An asperity-based statistical model for the adhesive friction of elastic\n  nominally flat rough contact interfaces: Contact mechanics-based models for the friction of nominally flat rough\nsurfaces have not been able to adequately capture certain key experimentally\nobserved phenomenona, such as the transition from a static friction peak to a\nlower level of sliding friction and the shear-induced contact area reduction\nthat has been observed in the pre-sliding regime especially for soft materials.\nHere, we propose a statistical model based on physically-rooted contact\nmechanics laws describing the micromechanics of individual junctions. The model\nconsiders the quasi-static tangential loading, up to full sliding, of the\ncontact between a smooth rigid flat surface and a nominally flat linear elastic\nrough surface comprising random independent spherical asperities, and accounts\nfor the coupling between adhesion and friction at the micro-junction level. The\nmodel qualitatively reproduces both the macroscopic shear-induced contact area\nreduction and, remarkably, the static friction peak without the need to\nexplicitly introduce two different friction levels. It also demonstrates how\nthe static friction peak and contact area evolution depend on the normal load\nand certain key microscale interface properties such as surface energy, mode\nmixity and frictional shear strength. \"Tougher\" interfaces (i.e. with larger\nsurface energy and smaller mode mixity parameter) are shown to result in a\nlarger real contact area and a more pronounced static friction peak. Overall,\nthis work provides important insights about how key microscale properties\noperating at the asperity level can combine with the surface statistics to\nreproduce important macroscopic responses observed in rough frictionalsoft\ncontact experiments."
    },
    {
        "anchor": "Kinetics of microribbon formation in a simplified model of amelogenin\n  biomacromolecules: We show that the kinetics of microribbon formation of amelogenin molecules is\nwell described by a combination of translational and rotational diffusion of a\nsimplified anisotropic bipolar model consisting of hydrophobic spherical\ncolloid particles and a point charge located on each particle surface. The\ncolloid particles interact via a standard depletion attraction while the point\ncharges interact through a screened Coulomb repulsion. We study the kinetics\nvia a Brownian dynamics simulation of both translational and rotational motions\nand show that the anisotropy brought in by the charge dramatically affects the\nkinetic pathway of cluster formation and our simple model captures the main\nfeatures of the experimental observations.",
        "positive": "Experimental evidence of seismic ruptures initiated by aseismic slip: Seismic faults release the stress accumulated during tectonic movement\nthrough rapid ruptures or slow slip events. The slow slip events play a crucial\nrole in the seismic cycle as they impact the occurrence of earthquakes.\nHowever, the mechanisms by which a slow-slip region affects the dynamics of\nfrictionally locked regions remain elusive. Here, building on model laboratory\nexperiments, we establish that a slow-slip region acts as a nucleation center\nfor seismic rupture, thereby enhancing earthquakes' frequency. We emulate\nslow-slip regions by introducing a granular material patch along part of a\nlaboratory fault. By measuring the response of the fault to shear, we show that\nthe role of the heterogeneity is to serve as a seed crack for rapid ruptures,\nreducing fault shear resistance. Additionally, by varying the external normal\nload, we show that the slow-slip region extends beyond the heterogeneity,\ndemonstrating that fault composition is not the only requirement for slow-slip,\nbut that load also plays a role. Our findings demonstrate that fracture\nconcepts single out the very origin of earthquake nucleation and slip dynamics\nin seismic faults. The interplay between slowly-slipping and locked regions\nthat we identify provides a promising avenue to monitor fault propagation and\nmitigate seismic hazards."
    },
    {
        "anchor": "Manipulating shear-induced non-equilibrium transitions by feedback\n  control: Using Brownian Dynamics (BD) simulations we investigate non-equilibrium\ntransitions of sheared colloidal films under controlled shear stress\n$\\sigma_{\\mathrm{xz}}$. In our approach the shear rate $\\dot\\gamma$ is a\ndynamical variable, which relaxes on a timescale $\\tau_c$ such that the\ninstantaneous, configuration-dependent stress $\\sigma_{\\mathrm{xz}}(t)$\napproaches a pre-imposed value. Investigating the dynamics under this\n\"feedback-control\" scheme we find unique behavior in regions where the flow\ncurve $\\sigma_{\\mathrm{xz}}(\\dot\\gamma)$ of the uncontrolled system is\nmonotonic. However, in non-monotonic regions our method allows to {\\em select}\nbetween dynamical states characterized by different in-plane structure and\nviscosities. Indeed, the final state strongly depends on $\\tau_c$ relative to\nan {\\em intrinsic} relaxation time of the uncontrolled system. The critical\nvalues of $\\tau_c$ are estimated on the basis of a simple model.",
        "positive": "Emergence of rheological properties in lattice Boltzmann simulations of\n  gyroid mesophases: We use a lattice Boltzmann (LB) kinetic scheme for modelling amphiphilic\nfluids that correctly predicts rheological effects in flow. No macroscopic\nparameters are included in the model. Instead, three-dimensional hydrodynamic\nand rheological effects are emergent from the underlying particulate\nconservation laws and interactions. We report evidence of shear thinning and\nviscoelastic flow for a self-assembled gyroid mesophase. This purely kinetic\napproach is of general importance for the modelling and simulation of complex\nfluid flows in situations when rheological properties cannot be predicted {\\em\na priori}."
    },
    {
        "anchor": "Propulsion by stiff elastic filaments in viscous fluids: Flexible filaments moving in viscous fluids are ubiquitous in the natural\nmicroscopic world. For example, the swimming of bacteria and spermatozoa as\nwell as important physiological functions at organ-level, such as the\ncilia-induced motion of mucus in the lungs, or individual cell-level, such as\nactin filaments or microtubules, all employ flexible filaments moving in\nviscous fluids. As a result of fluid-structure interactions, a variety of\nnonlinear phenomena may arise in the dynamics of such moving flexible\nfilaments. In this paper we derive the mathematical tools required to study\nfilament-driven propulsion in the asymptotic limit of stiff filaments. Motion\nin the rigid limit leads to hydrodynamic loads which deform the filament and\nimpact the filament propulsion. We first derive the general mathematical\nformulation and then apply it to the case of a helical filament, a situation\nrelevant for the swimming of flagellated bacteria and for the transport of\nartificial, magnetically actuated motors. We find that, as a result of\nflexibility, the helical filament is either stretched or compressed (conforming\nprevious studies) and its axis also bends, a new result which we interpret\nphysically. We then explore and interpret the dependence of the perturbed\npropulsion speed due to the deformation on the relevant dimensionless dynamic\nand geometric parameters.",
        "positive": "Possible Pressure Effect for Superconductors: We make an estimate of the possible range of $\\Delta T_c$ induced by\nhigh-pressure effects in post-metallic superconductors by using the theory of\n{\\it extended irreversible/reversible thermodynamics} and Pippard's length\nscale. The relationship between the increment of the superconducting\ntemperature and the increase of the pressure is parabolic."
    },
    {
        "anchor": "Slowing-down of non-equilibrium concentration fluctuations in\n  confinement: Fluctuations in a fluid are strongly affected by the presence of a\nmacroscopic gradient making them long-ranged and enhancing their amplitude.\nWhile small-scale fluctuations exhibit diffusive lifetimes, larger-scale\nfluctuations live shorter because of gravity, as theoretically and\nexperimentally well-known. We explore here fluctuations of even larger size,\ncomparable to the extent of the system in the direction of the gradient, and\nfind experimental evidence of a dramatic slowing-down in their dynamics. We\nrecover diffusive behaviour for these strongly-confined fluctuations, but with\na diffusion coefficient that depends on the solutal Rayleigh number. Results\nfrom dynamic shadowgraph experiments are complemented by theoretical\ncalculations and numerical simulations based on fluctuating hydrodynamics, and\nexcellent agreement is found. The study of the dynamics of non-equilibrium\nfluctuations allows to probe and measure the competition of physical processes\nsuch as diffusion, buoyancy and confinement.",
        "positive": "Nano-pore based characterization of branched polymers: We propose a novel characterization method of randomly branched polymers\nbased on the geometrical property of such objects in confined spaces. The\ncentral idea is that randomly branched polymers exhibit passing/clogging\ntransition across the nano-channel as a function of the channel size. This\ncritical channel size depends on the degree of the branching, whereby allowing\nthe extraction of the branching information of the molecule."
    },
    {
        "anchor": "A comment on \"Ab initio calculations of pressure-dependence of\n  high-order elastic constants using finite deformations approach\" by I.\n  Mosyagin, A.V. Lugovskoy, O.M. Krasilnikov, Yu.Kh. Vekilov, S.I. Simak and\n  I.A. Abrikosov: Recently, I. Mosyagin, A.V. Lugovskoy, O.M. Krasilnikov, Yu.Kh. Vekilov, S.I.\nSimak and I.A. Abrikosov in the paper: \"Ab initio calculations of\npressure-dependence of high-order elastic constants using finite deformations\napproach\"[Computer Physics Communications 220 (2017) 2030] presented a\ndescription of a technique for ab initio calculations of the pressure\ndependence of second- and third-order elastic constants. Unfortunately, the\nwork contains serious and fundamental flaws in the field of finite-deformation\nsolid mechanics.",
        "positive": "Solvent quality and solvent polarity in polypeptides: Using molecular dynamics and thermodynamic integration, we report on the\nsolvation process in water and in cyclohexane of seven polypeptides (GLY, ALA,\nILE, ASN, LYS, ARG, GLU). The polypeptides are selected to cover the full\nhydrophobic scale while varying their chain length from tri- to\nundeca-homopeptides provide indications on possible non-additivity effects as\nwell as the role of the peptide backbone in the overall stability of the\npolypeptides. The use of different solvents and different polypeptides allows\nus to investigate the relation between solvent quality -- the capacity of a\ngiven solvent to fold a given biopolymer often described on a scale ranging\nfrom \"good\" to \"poor\", and solvent polarity -- related to the specific\ninteractions of any solvent with respect to a reference solvent. Undeca-glycine\nis found to be the only polypeptides to have a proper stable collapse in water\n(polar solvent), with the other hydrophobic polypetides displaying in water\nrepeated folding and unfolding events and with polar polypeptides presenting a\neven more complex behavior. By contrast, all polypeptides but none are found to\nkeep an extended conformation in cyclohexane, irrespective of their polarity.\nAll considered polypeptides are also found to have a favorable solvation free\nenergy independently of the solvent polarity and their intrinsic\nhydrophobicity, clearly highlighting the prominent stabilizing role of the\npeptide backbone, with the solvation process largely enthalpically dominated in\npolar polypeptides and partially entropically driven for hydrophobic\npolypeptides. Our study thus reveals the complexity of the solvation process of\npolypeptides defying the common view \" like dissolves like\", with the solute\npolarity playing the most prominent role. The absence of a mirror symmetry upon\nthe inversion of polarities of both the solvent and the polypeptides is\nconfirmed."
    },
    {
        "anchor": "Connectivity, Dynamics, and Structure in a Tetrahedral Network Liquid: We report a detailed computational study by Brownian Dynamics simulations of\nthe structure and dynamics of a liquid of patchy particles which develops an\namorphous tetrahedral network upon decreasing temperature. The highly\ndirectional particle interactions allows us to investigate the system\nconnectivity by discriminating the total set of particles into different\npopulations according to a penta-modal distribution of bonds per particle. With\nthis methodology we show how the particle bonding process is not randomly\nindependent but it manifests clear bond correlations at low temperatures. We\nfurther explore the dynamics of the system in real space and establish a clear\nrelation between particle mobility and particle connectivity. In particular, we\nprovide evidence of anomalous diffusion at low temperatures and reveal how the\ndynamics is affected by the short-time hopping motion of the weakly bounded\nparticles. Finally we widely investigate the dynamics and structure of the\nsystem in Fourier space and identify two quantitatively similar length scales,\none dynamic and the other one static, which increase upon cooling the system\nand reach distances of the order of few particle diameters. We summarize our\nfindings in a qualitative picture where the low temperature regime of the\nviscoelastic liquid is understood in terms of an evolving network of long time\nmetastable cooperative domains of particles.",
        "positive": "Denaturation transition of stretched DNA: We generalize the Poland-Scheraga model to consider DNA denaturation in the\npresence of an external stretching force. We demonstrate the existence of a\nforce-induced DNA denaturation transition and obtain the temperature-force\nphase diagram. The transition is determined by the loop exponent $c$ for which\nwe find the new value $c=4\\nu-1/2$ such that the transition is second order\nwith $c=1.85<2$ in $d=3$. We show that a finite stretching force $F$\ndestabilizes DNA, corresponding to a lower melting temperature $T(F)$, in\nagreement with single-molecule DNA stretching experiments."
    },
    {
        "anchor": "Contact mechanics of fractal surfaces by spline assisted discretisation: We present a newly developed approach for the calculation of interfacial\nstiffness and contact area evolution between two rough bodies exhibiting self\naffine surface structures. Using spline assisted discretization to define\nlocalised contact normals and surface curvatures we interpret the mechanics of\nsimulated non-adhesive elastic surface-profiles subjected to normal loading by\nexamining discrete contact points as projected Hertzian spheres. The analysis\nof rough-to-rough contact mechanics for surface profiles exhibiting fractal\nstructures, with fractal dimensions in the regime 1 2, reveals the significant\neffect of surface fractality on contact mechanics and compliance with surfaces\nhaving the same mean roughness but higher fractality showing lower contact\nstiffness in conditions of initial contact for a given load. The predicted\nlinear development of true contact area with load was found to be consistent\nwith diverse existing numerical and experimental studies. Results from this\nmodel demonstrate the applicability of the developed method for the meaningful\ncontact analysis of hierarchical structures with implications for modelling\ntribological interactions between pairs of rough surfaces",
        "positive": "Effective Interactions Between Rigid Polyelectrolytes and Like-charged\n  Planar Surfaces: We study the effective interaction between a planar array of uniformly\nnegatively charged, stiff rods parallel to a negatively charged planar\nsubstrate in the absence of salt in a continuous, isotropic dielectric medium.\nUsing Brownian dynamics simulations, we examine the general effects of\ncounterion valence, rod spacing, macroion charge densities, and the rod size on\nthe attractive rod-surface interaction force. At room temperature divalent as\nwell as monovalent counterions mediate an interaction that can be repulsive or\nattractive upon adjusting either the macroion charge densities or the rod\nradius. Finally, we examine the effects of discretizing the surface charge as\nlaterally mobile monovalent anions and of electrostatic images in the\nsubstrate."
    },
    {
        "anchor": "Structure and interaction of flexible dendrimers in concentrated\n  solution: We study the influence of mutual interaction on the conformation of flexible\npoly(propyleneamine) dendrimers of fourth generation in concentrated solution.\nMixtures of dendrimers with protonated and deuterated end groups are\ninvestigated by small-angle neutron scattering up to volume fractions of 0.23.\nThis value is in the range of the overlap concentration of the dendrimers. The\ncontrast between the solute and the solvent was varied by using mixtures of\nprotonated and deuterated solvents. This allows us to investigate the partial\nstructure factors of the deuterated dendrimers in detail. An analysis of the\nmeasured scattering intensities reveals that the shape of the flexible\ndendrimers is practically independent of the concentration in contrast to the\npronounced conformational changes of flexible linear polymers.",
        "positive": "Water in a Polymeric Electrolyte Membrane: Sorption/Desorption and\n  Freezing phenomena: Nafion is a perfluorosulfonated polymer, widely used in Proton Exchange\nMembrane Fuel Cells. This polymer adopts a complex structural organisation\nresulting from the microsegregation between hydrophobic backbones and\nhydrophilic sulfonic acid groups. Upon hydration appear water-filled channels\nand cavities, in which are released the acidic protons to form a solution of\nhydronium ions in water embedded in the polymer matrix. Below 273 K, a\nphenomenon of water sorption/desorption occurs, whose origin is still an open\nquestion. Performing neutron diffraction, we monitored the quantity of ice\nformed during the sorption/desorption as a function of temperature down to 180\nK. Upon cooling, we observe that ice forms outside of the membrane and\ncrystallises in the hexagonal Ih form. Simultaneously, the membrane shrinks and\ndehydrate, leading to an increase of the hydronium ions concentration inside\nthe matrix. Reversibly, the ice melts and the membrane re-hydrate upon heating.\nA model of solution, whose freezing point varies with the hydronium\nconcentration, is proposed to calculate the quantity of ice formed as a\nfunction of temperature. The quantitative agreement between the model and\nexperimental data explains the smooth and reversible behavior observed during\nthe sorption or desorption of water, pointing out the origin of the phenomena.\nThe proposed picture reconciles both confinement and entropic effects. Other\nexamples of water filled electrolyte nano-structures are eventually discussed,\nin the context of clarifying the conditions for water transport at low\ntemperature."
    },
    {
        "anchor": "Kinematic matrix theory and universalities in self-propellers and active\n  swimmers: We describe an efficient and parsimonious matrix-based theory for studying\nthe ensemble behavior of self-propellers and active swimmers, such as\nnanomotors or motile bacteria, that are typically studied by\ndifferential-equation-based Langevin or Fokker-Planck formalisms. The kinematic\neffects for elementary processes of motion are incorporated into a matrix,\ncalled the \"kinematrix\", from which we immediately obtain correlators and the\nmean and variance of angular and position variables (and thus effective\ndiffusivity) by simple matrix algebra. The kinematrix formalism enables us\nrecast the behaviors of a diverse range of self-propellers into a unified form,\nrevealing universalities in their ensemble behavior in terms of new emergent\ntime scales. Active fluctuations and hydrodynamic interactions can be expressed\nas an additive composition of separate self-propellers.",
        "positive": "Pressure Profile Calculation with Mesh Ewald Methods: The importance of calculating pressure profiles across liquid interfaces is\nincreasingly gaining recognition, and efficient methods for the calculation of\nlong-range contributions are fundamental in addressing systems with a large\nnumber of charges. Here, we show how to compute the local pressure contribution\nfor mesh-based Ewald methods, retaining the typical N log N scaling as a\nfunction of the lattice nodes N. This is a considerable improvement on existing\nmethods, which include approximating the electrostatic contribution using a\nlarge cut-off and the, much slower, Ewald calculation. As an application, we\ncalculate the contribution to the pressure profile across the water/vapour\ninterface, coming from different molecular layers, both including and removing\nthe effect of thermal capillary waves. We compare the total pressure profile\nwith the one obtained using the cutoff approximation for the calculation of the\nstresses, showing that the stress distribution obtained by the Harasima and\nIrving-Kirkwood are quite similar and shifted with respect to each other at\nmost 0.05~nm."
    },
    {
        "anchor": "A thermodynamic basis for implicit rate-type constitutive relations\n  describing the inelastic response of solids undergoing finite deformation: Implicit rate-type constitutive relations utilizing discontinuous functions\nprovide a novel approach to the purely phenomenological description of the\ninelastic response of solids undergoing finite deformation. However, this type\nof constitutive relations has been so far considered only in the purely\nmechanical setting, and the complete thermodynamic basis is largely missing. We\naddress this issue, and we develop a thermodynamic basis for such constitutive\nrelations. In particular, we focus on the thermodynamic basis for the classical\nelastic--perfectly plastic response, but the framework is flexible enough to\ndescribe another types of inelastic response as well.",
        "positive": "Dynamic and Thermodynamic Origins of Motility-Induced Phase Separation: Active matter systems are inherently out of equilibrium and break the\ndetailed balance (DB) at the microscopic scale, exhibiting vital collective\nphenomena such as motility-induced phase separation (MIPS). Here, we introduce\na coarse-grained mapping method to probe DB breaking in the density-energy\nphase space, which allows us to reveal the dynamic and thermodynamic origins of\nMIPS based on nonequilibrium potential and flux landscape theory. Hallmarks of\nnonequilibrium properties are manifested by identifying the visible probability\nflux in the coarse-grained phase space. Remarkably, the flux for the system\nwith the activity lower than the MIPS threshold tends to ``tear up\" the single\npotential well of the uniform-density phase to create two wells of phases with\ndifferent densities, presenting directly that the nonequilibrium flux is the\ndynamic origin of MIPS. Moreover, we find that the obtained entropy production\nrate (EPR) of the system undergoes a transition from nearly independent of\nactivity to increasing proportionally as activity increases after the single\nwell is \"teared up\". The transition of EPR's scaling behavior might provide a\nhint of the thermodynamic origin of MIPS in the coarse-grained space. Our\nfindings propose a new route to explore the nonequilibrium nature of active\nsystems, and provide new insights into dynamic and thermodynamic properties of\nMIPS."
    },
    {
        "anchor": "The Jamming Transition and the Marginally Stable Solid: We review the physics of jamming from the theoretical, experimental and\nnumerical perspectives. We summarize the mean-field theory of jamming and the\nmarginally stable solid phase, with particular emphasis on the connection with\nthe Replica Symmetry Breaking theory of glasses. We report validations of the\nmean-field theory of jamming from experimental and numerical studies of\ncritical behaviors near the transition. In particular, we describe the physics\nof jamming of frictionless, spherical particles, as well as more recent work on\njamming of frictionless, non-spherical particles and frictional, nearly\nspherical particles. We also present current efforts in expanding the\nmean-field theory to systems that more closely resemble externally driven\ngranular media, cell aggregates, and active colloidal suspensions.",
        "positive": "Chiral Active Particles are Sensitive Reporter to Environmental Geometry: Chiral active particles (CAPs) are self-propelling particles that break\ntime-reversal symmetry by orbiting or spinning, leading to intriguing\nbehaviors. Here, we examined the dynamics of CAPs moving in 2D lattices of disk\nobstacles through active Brownian dynamics simulations and granular experiments\nwith grass seeds. We find that the effective diffusivity of the CAPs is\nsensitive to the structure of the obstacle lattice, a feature absent in achiral\nactive particles. We further studied the transport of CAPs in obstacle arrays\nunder an external field and found a reentrant directional locking effect, which\ncan be used to sort CAPs with different activities. Finally, we demonstrated\nthat the parallelogram lattice of obstacles without mirror symmetry can\nseparate clockwise and counter-clockwise CAPs. The mechanisms of the above\nthree novel phenomena are qualitatively explained. As such, our work provides a\nbasis for designing chirality-based tools for single-cell diagnosis and\nseparation, and active particle-based environmental sensors."
    },
    {
        "anchor": "Thermodynamic metric geometry of the two-state ST2 model for supercooled\n  water: Liquid water has anomalous liquid properties, such as its density maximum at\n4\\degree C. An attempt at theoretical explanation proposes a liquid-liquid\nphase transition line in the supercooled liquid state, with coexisting\nlow-density (LDL) and high-density (HDL) liquid states. This line terminates at\na critical point. It is assumed that the LDL state possesses mesoscopic\ntetrahedral structures that give it solid-like properties, while the HDL is a\nregular random liquid. But the short-lived nature of these solid-like\nstructures make them difficult to detect directly. We take a thermodynamic\napproach instead, and calculate the thermodynamic Ricci curvature scalar $R$ in\nthe metastable liquid regime. It is believed that solid-like structures signal\ntheir presence thermodynamically by a positive sign for $R$, with a negative\nsign typically present in less organized fluid states. Using thermodynamic data\nfrom ST2 computer simulations fit to a mean field (MF) two state equation of\nstate, we find significant regimes of positive $R$ in the LDL state, supporting\nthe proposal of solid-like structures in liquid water. In addition, we review\nthe theory, compute critical exponents, demonstrate the large reach of the MF\ncritical regime, and calculate the Widom line using $R$.",
        "positive": "Bubble Shape and Transport During LCM Processes: Experimental Modeling\n  in a T-Junction Tube: Long fiber composite materials can be elaborated by Liquid Composite Molding\n(LCM), a family of processes where fibrous preforms are injected by a low\nviscosity resin. During this process, we have to pay particular attention to\nthe void formation inside the preform because it could modify the material\nfinal characteristics. Indeed, a preform presents two different porosity\nscales: between yarns called macropores and inside yarns, namely micropores."
    },
    {
        "anchor": "Shear-induced Transitions in Ternary Polymeric System: The first three-dimensional simulation of shear-induced phase transitions in\na polymeric system has been performed. The method is based on dynamic\ndensity-functional theory. The pathways between a bicontinuous phase with\ndeveloping gyroid mesostructure and a lamellar/cylinder phase coexistence are\ninvestigated for a mixture of flexible triblock ABA-copolymer and solvent under\nsimple steady shear.",
        "positive": "Solid Propellants: Solid propellants are energetic materials used to launch and propel rockets\nand missiles. Although their history dates to the use of black powder more than\ntwo millennia ago, greater performance demands and the need for \"insensitive\nmunitions\" that are resistant to accidental ignition have driven much research\nand development over the past half-century. The focus of this review is the\nmaterial aspects of propellants, rather than their performance, with an\nemphasis on the polymers that serve as binders for oxidizer particles and as\nfuel for composite propellants. The prevalent modern binders are discussed\nalong with a discussion of the limitations of state-of-the-art modeling of\ncomposite motors."
    },
    {
        "anchor": "Stability analysis of twist grain boundaries in lamellar phases of block\n  copolymers: Twist grain boundaries are widely observed in lamellar phases of block\ncopolymers. A mesoscopic model of the copolymer is used to obtain stationary\nconfigurations that include a twist grain boundary, and to analyze their\nstability against long wavelength perturbations. The analysis presented is\nvalid in the weak segregation regime, and includes direct numerical solution of\nthe governing equations as well as a multiple scale analysis. We find that a\ntwist boundary configuration with arbitrary misorientation angle can be well\ndescribed by two modes, and obtain the equations for their slowly varying\namplitudes. The width of the boundary region is seen to scale as\n$\\epsilon^{-1/4}$, with $\\epsilon$ being the dimensionless distance to the\norder-disorder transition. We finally present the results of the linear\nstability analysis of the planar boundary.",
        "positive": "Static and dynamic scaling behavior of a polymer melt model with\n  triple-well bending potential: We perform molecular-dynamics simulations for polymer melts of the\ncoarse-grained polyvinyl alcohol model that crystallizes upon slow cooling. To\nestablish the properties of its high temperature liquid state as a reference\npoint, we characterize in detail the structural features of equilibrated\npolymer melts with chain lengths $5\\le N \\le 1000$ at a temperature slightly\nabove their crystallization temperature. We find that the conformations of\nsufficiently long polymers with $N >50$ obey essentially the Flory's ideality\nhypothesis. The chain length dependence of the end-to-end distance and the\ngyration radius follow the scaling predictions of ideal chains and the\nprobability distributions of the end-to-end distance, and form factors are in\ngood agreement with those of ideal chains. The intrachain correlations reveal\nevidences for incomplete screening of self-interactions. However, the observed\ndeviations are small. Our results rule out any pre-ordering or mesophase\nstructure formation that are proposed as precursors of polymer crystallization\nin the melt. Moreover, we characterize in detail primitive paths of long\nentangled polymer melts and we examine scaling predictions of Rouse and the\nreptation theory for the mean squared displacement of monomers and polymers\ncenter of mass."
    },
    {
        "anchor": "New insight into cataract formation -- enhanced stability through mutual\n  attraction: Small-angle neutron scattering experiments and molecular dynamics simulations\ncombined with an application of concepts from soft matter physics to complex\nprotein mixtures provide new insight into the stability of eye lens protein\nmixtures. Exploring this colloid-protein analogy we demonstrate that weak\nattractions between unlike proteins help to maintain lens transparency in an\nextremely sensitive and non-monotonic manner. These results not only represent\nan important step towards a better understanding of protein condensation\ndiseases such as cataract formation, but provide general guidelines for tuning\nthe stability of colloid mixtures, a topic relevant for soft matter physics and\nindustrial applications.",
        "positive": "Confinement twists achiral liquid crystals and causes chiral liquid\n  crystals to twist in the opposite handedness: Cases in and around sessile\n  droplets: We study the chiral symmetry breaking and metastability of confined nematic\nlyotropic chromonic liquid crystal (LCLC) with and without chiral dopants. The\nisotropic-nematic coexistence phase of the LCLC renders two confining\ngeometries: sessile isotropic(I) droplets surrounded by the nematic(N) phase\nand sessile nematic droplets immersed in the isotropic background. In the\nachiral system with no dopants, LCLC's elastic anisotropy and topological\ndefects induce a spontaneous twist deformation to lower the energetic penalty\nof splay deformation, resulting in spiral optical textures under crossed\npolarizers both in the I-in-N and N-in-I systems. While the achiral system\nexhibits both handednesses with an equal probability, a small amount of the\nchiral dopant breaks the balance. Notably, in contrast to the homochiral\nconfiguration of a chirally doped LCLC in bulk, the spiral texture of the\ndisfavored handedness appears with a finite probability both in the I-in-N and\nN-in-I systems. We propose director field models explaining how chiral symmetry\nbreaking arises by the energetics and the opposite-twist configurations exist\nas meta-stable structures in the energy landscape. These findings help us\ncreate and control chiral structures using confined LCs with large elastic\nanisotropy."
    },
    {
        "anchor": "The nature of the glass and gel transitions in sticky spheres: Glasses and gels are the two dynamically arrested, disordered states of\nmatter. Despite their importance, their similarities and differences remain\nelusive, especially at high density. We identify dynamical and structural\nsignatures which distinguish the gel and glass transitions in a colloidal model\nsystem of hard and \"sticky\" spheres. Gelation is induced by crossing the\ngas-liquid phase-separation line and the resulting rapid densification of the\ncolloid-rich phase leads to a sharp change in dynamics and local structure.\nThus, we find that gelation is first-order-like and can occur at much higher\ndensities than previously thought: far from being low-density networks, gels\nhave a clear \"thermodynamic\" definition which nevertheless leads to a\nnon-equilibrium state with a distinct local structure characteristic of a\nrapidly quenched glass. In contrast, approaching the glass transition, the\ndynamics slow continuously accompanied by the emergence of local five-fold\nsymmetric structure. Our findings provide a general thermodynamic, kinetic, and\nstructural basis upon which to distinguish gelation from vitrification.",
        "positive": "Chain connectivity and conformational variability of polymers: Clues to\n  an adequate thermodynamic description of their solutions II: Composition\n  dependence of Flory-Huggins interaction parameters: In part I of this contribution we have reported how the Flory-Huggins\ninteraction parameter chi can be modeled as a function of chain length within\nthe composition range of pair interaction between the macromolecules by means\nof the three parameters alpha, zeta and lambda. This contribution presents the\nextension of the approach to arbitrary volume fractions of the polymer and its\napplication to published data. The resulting equation is simple and requires\nonly the additional parameter ny to incorporate the composition dependence. Its\nemployment to experimental data is very much facilitated by substituting for\nthe limiting value of chi at infinite dilution. Furthermore the expression can\nin good approximation be simplified such that only two parameters need to be\nadjusted. This relation is capable of describing all types of composition\ndependencies reported in the literature, including the hitherto\nincomprehensible occurrence of pronounced minima. For a given system the\nevaluation of the chain length dependence of chi at high dilution reported in\npart I, and the present evaluation of the composition dependence of chi yield\nthe same values for the conformational response zeta. Similarly both types of\nmeasurements generate the same interdependence between zeta and alpha. The\nphysical meaning of the different parameters and the reason for the observed\ncorrelations are discussed."
    },
    {
        "anchor": "Effective surface interactions mediated by adhesive particles: In biomimetic and biological systems, interactions between surfaces are often\nmediated by adhesive molecules, nanoparticles, or colloids dispersed in the\nsurrounding solution. We present here a general, statistical-mechanical model\nfor two surfaces that interact via adhesive particles. The effective,\nparticle-mediated interaction potential of the surfaces is obtained by\nintegrating over the particles' degrees of freedom in the partition function.\nInterestingly, the effective adhesion energy of the surfaces exhibits a maximum\nat intermediate particle concentrations, and is considerably smaller both at\nlow and high concentrations. The effective adhesion energy corresponds to a\nminimum in the interaction potential at surface separations slightly larger\nthan the particle diameter, while a secondary minimum at surface contact\nreflects depletion interactions. Our results can be generalized to surfaces\nwith specific receptors for solute particles, and have direct implications for\nthe adhesion of biomembranes and for phase transitions in colloidal systems.",
        "positive": "Thermorheological Complexity in Polymers and the Problem of the Glass\n  Transition: A current focus in studies of the glass transition is the role of dynamic\nheterogeneities. Although these efforts may clarify the origin of the\nspectacular change in properties of liquids approaching vitrification, we point\nout that a seemingly related phenomenon, thermorheological complexity in\npolymers, must involve different mechanisms. In particular, as seen from\nconsideration of various properties involving the chain dynamics, averaging\nover different length and time scales cannot offer a resolution to the problem\nof thermorheological complexity."
    },
    {
        "anchor": "Odd elasticity: Hooke's law states that the forces or stresses experienced by an elastic\nobject are proportional to the applied deformations or strains. The number of\ncoefficients of proportionality between stress and strain, i.e., the elastic\nmoduli, is constrained by energy conservation. In this Letter, we lift this\nrestriction and generalize linear elasticity to active media with\nnon-conservative microscopic interactions that violate mechanical reciprocity.\nThis generalized framework, which we dub odd elasticity, reveals that two\nadditional moduli can exist in a two-dimensional isotropic solid with active\nbonds. Such an odd-elastic solid can be regarded as a distributed engine: work\nis locally extracted, or injected, during quasi-static cycles of deformation.\nUsing continuum equations, coarse-grained microscopic models, and numerical\nsimulations, we uncover phenomena ranging from activity-induced auxetic\nbehavior to wave propagation powered by self-sustained active elastic cycles.\nBesides providing insights beyond existing hydrodynamic theories of active\nsolids, odd elasticity suggests design principles for emergent autonomous\nmaterials.",
        "positive": "Phase behaviour of the confined lattice gas Lebwohl-Lasher model: The phase behaviour of the Lebwohl-Lasher lattice gas model (one of the\nsimplest representations of a nematogenic fluid) confined in a slab is\ninvestigated by means of extensive Monte Carlo simulations. The model is known\nto yield a first order gas-liquid transition in both the 2D and 3D limits, that\nis coupled with an orientational order-disorder transition. This latter\ntransition happens to be first order in the 3D limit and it shares some\ncharacteristic features with the continuous defect mediated\nBerezinskii-Kosterlitz-Thouless transition in 2D. In this work we will analyze\nin detail the behaviour of this system taking full advantage of the lattice\nnature of the model and the particular symmetry of the interaction potential,\nwhich allows for the use of efficient cluster algorithms."
    },
    {
        "anchor": "The non-local repercussions of partial jamming in dense granular flows: This paper establishes a link between the non-local behaviour of granular\nmaterials and the presence of transient clusters of jammed particles within the\nflow. These clusters are first evidenced in simulated dense granular flows\nsubjected to plane shear, and are found to originate from a mechanism of\nmultiple orthogonal shear banding. A continuum non-local model, similar in form\nto the non-local Cooperative model, is then derived by considering the spatial\nredistribution of vorticity induced by these clusters. The non-locality length\nscale is thus expressed in terms of the cluster size. The purely kinematic\nnature of this derivation indicates that non-local behaviour should be expected\nin all glassy materials, regardless of their local constitutive law, as long as\nthey partially jam during flow.",
        "positive": "Impermeability effects in three-dimensional vesicles: We analyse the effects that the impermeability constraint induces on the\nequilibrium shapes of a three-dimensional vesicle hosting a rigid inclusion. A\ngiven alteration of the inclusion and/or vesicle parameters leads to shape\nmodifications of different orders of magnitude, when applied to permeable or\nimpermeable vesicles. Moreover, the enclosed-volume constraint wrecks the\nuniqueness of stationary equilibrium shapes, and gives rise to pear-shaped or\nstomatocyte-like vesicles."
    },
    {
        "anchor": "Force induced unfolding of bio-polymers in a cellular environment: A\n  model study: Effect of molecular crowding and confinement experienced by protein in the\ncell during unfolding has been studied by modeling a linear polymer chain on a\npercolation cluster. It is known that internal structure of the cell changes in\ntime, however, they do not change significantly from their initial structure.\nIn order to model this we introduce the correlation among the different\ndisorder realizations. It was shown that the force-extension behavior for\ncorrelated disorder in both constant force ensemble (CFE) and constant distance\nensemble (CDE) is significantly different than the one obtained in absence of\nmolecular crowding.",
        "positive": "Slow and fast particles in shear-driven jamming: critical behavior: We do extensive simulations of a simple model of shear-driven jamming in two\ndimensions to analyze the velocity distribution at different densities $\\phi$\naround the jamming density $\\phi_J$ and at different low shear strain rates,\n$\\dot\\gamma$. We then find that the velocity distribution is made up of two\nparts which are related to two different physical processes which we call the\nslow process and the fast process as they are dominated by the slower and the\nfaster particles, respectively. Earlier scaling analyses have shown that the\nshear viscosity $\\eta$, which diverges as the jamming density is approached\nfrom below, consists of two different terms and we present strong evidence that\nthese terms are related to the two different processes: the leading divergence\nis due to the fast process whereas the correction-to-scaling term is due to the\nslow process. The analysis of the slow process is possible thanks to the\nobservation that the velocity distribution for different $\\dot\\gamma$ and\n$\\phi$ at and around the shear-driven jamming transition, has a peak at low\nvelocities and that the distribution has a constant shape up to and slightly\nabove this peak. We then find that it is possible to express the contribution\nto the shear viscosity due to the slow process in terms of height and position\nof the peak in the velocity distribution and find that this contribution\nmatches the correction-to-scaling term, determined through a standard critical\nscaling analysis. A further observation is that the collective particle motion\nis dominated by the slow process. In contrast to the usual picture in critical\nphenomena with a direct link between the diverging correlation length and a\ndiverging order parameter, we find that correlations and shear viscosity\ndecouple since they are controlled by different sets of particles and that\nshear-driven jamming is thus an unusual kind of critical phenomenon."
    },
    {
        "anchor": "Pressure Effects in Supercooled Water: Comparison between a 2D Model of\n  Water and Experiments for Surface Water on a Protein: Experiments in bulk water confirm the existence of two local arrangements of\nwater molecules with different densities, but, because of inevitable freezing\nat low temperature $T$, can not ascertain whether the two arrangements separate\nin two phases. To avoid the freezing, new experiments measure the dynamics of\nwater at low $T$ on the surface of proteins, finding a crossover from a\nnon-Arrhenius regime at high $T$ to a regime that is approximately Arrhenius at\nlow $T$. Motivated by these experiments, Kumar et al. [Phys. Rev. Lett. 100,\n105701 (2008)] investigated, by Monte Carlo simulations and mean field\ncalculations, the relation of the dynamic crossover with the coexistence of two\nliquid phases in a cell model for water and predict that: (i) the dynamic\ncrossover is isochronic, i.e. the value of the crossover time $\\tau_{\\rm L}$ is\napproximately independent of pressure $P$; (ii) the Arrhenius activation energy\n$E_{\\rm A}(P)$ of the low-$T$ regime decreases upon increasing $P$; (iii) the\ntemperature $T^*(P)$ at which $\\tau$ reaches a fixed macroscopic time\n$\\tau^*\\geq \\tau_{\\rm L}$ decreases upon increasing $P$; in particular, this is\ntrue also for the crossover temperature $T_{\\rm L}(P)$ at which $\\tau=\\tau_{\\rm\nL}$. Here, we compare these predictions with recent quasi elastic neutron\nscattering (QENS) experiments performed by X.-Q. Chu {\\it et al.} on hydrated\nproteins at different values of $P$. We find that the experiments are\nconsistent with these three predictions.",
        "positive": "Generalized inverse patchy colloid model: We generalize the inverse patchy colloid model that was originally developed\nfor heterogeneously charged particles with two identical polar patches and an\noppositely charged equator to a model that can have a considerably richer\nsurface pattern. Based on a Debye-Hueckel framework, we propose a\ncoarse-grained description of the effective pair interactions that is\napplicable to particles with an arbitrary patch decoration. We demonstrate the\nversatility of this approach by applying it to models with (i) two differently\ncharged and/or sized patches, and (ii) three, possibly different patches."
    },
    {
        "anchor": "Coarse Grained Computations for a Micellar System: We establish, through coarse-grained computation, a connection between\ntraditional, continuum numerical algorithms (initial value problems as well as\nfixed point algorithms) and atomistic simulations of the Larson model of\nmicelle formation. The procedure hinges on the (expected) evolution of a few\nslow, coarse-grained mesoscopic observables of the MC simulation, and on\n(computational) time scale separation between these and the remaining \"slaved\",\nfast variables. Short bursts of appropriately initialized atomistic simulation\nare used to estimate the (coarse-grained, deterministic) local dynamics of the\nevolution of the observables. These estimates are then in turn used to\naccelerate the evolution to computational stationarity through traditional\ncontinuum algorithms (forward Euler integration, Newton-Raphson fixed point\ncomputation). This \"equation-free\" framework, bypassing the derivation of\nexplicit, closed equations for the observables (e.g. equations of state) may\nprovide a computational bridge between direct atomistic / stochastic simulation\nand the analysis of its macroscopic, system-level consequences.",
        "positive": "Characteristic interfacial structure behind a rapidly moving contact\n  line: In forced wetting, a rapidly moving surface drags with it a thin layer of\ntrailing fluid as it is plunged into a second fluid bath. Using high-speed\ninterferometry, we find characteristic structure in the thickness of this layer\nwith multiple thin flat triangular structures separated by much thicker\nregions. These features, depending on liquid viscosity and penetration\nvelocity, are robust and occur in both wetting and de-wetting geometries. Their\npresence clearly shows the inadequacy of theoretical analysis that ignores the\ninstability in the transverse direction."
    },
    {
        "anchor": "Interfaces of Modulated Phases: Numerically minimizing a continuous free-energy functional which yields\nseveral modulated phases, we obtain the order-parameter profiles and\ninterfacial free energies of symmetric and non-symmetric tilt boundaries within\nthe lamellar phase, and of interfaces between coexisting lamellar, hexagonal,\nand disordered phases. Our findings agree well with chevron, omega, and\nT-junction tilt-boundary morphologies observed in diblock copolymers and\nmagnetic garnet films.",
        "positive": "Shear thickening of suspensions of dimeric particles: In this article, I study the shear thickening of suspensions of frictional\ndimers by the mean of numerical simulations. I report the evolution of the main\nparameters of shear thickening, such as the jamming volume fractions in the\nunthickened and thickened branches of the flow curves, as a function of the\naspect ratio of the dimers. The explored aspect ratios range from $1$ (spheres)\nto $2$ (dimers made of two kissing spheres). I find a rheology qualitatively\nsimilar than the one for suspensions of spheres, except for the first normal\nstress difference $N_1$, which I systematically find negative for small\nasphericities. I also investigate the orientational order of the particles\nunder flow. Overall, I find that dense suspensions of dimeric particles share\nmany features with dry granular systems of elongated particles under shear,\nespecially for the frictional state at large applied stresses. For the\nfrictionless state at small stresses, I find that suspensions jam at lower\nvolume fraction than dry systems, and that this difference increases with\nincreasing aspect ratio. Moreover, in this state I find a thus far unobserved\nalignment of the dimers along the vorticity direction, as opposed to the\ncommonly observed alignment with a direction close to the flow direction."
    },
    {
        "anchor": "Adsorption of Polylysine on the Surface of the DMPS Monolayer: The effect of the adsorption of a polypeptide on the lateral interaction of\ndimyristoylphosphatidylserine molecules in different phase states on the\nsurface of a 10\\,mM KCl aqueous solution has been studied. Changes in the\nsurface pressure and Volta potential induced by the adsorption of large\npoly-D-lysine molecules (about 200 links in a chain) have been determined at\ndifferent areas per lipid molecule in a monolayer. The adsorption of\nmacromolecules noticeably increases the elasticity of the monolayer under\nlateral compression in the liquid expanded state of lipid and reduces the\neffective dipole moment from 0.48 to 0.38 D. These properties are in\nqualitative agreement with X-ray reflectometry data for the lipid monolayer\nobtained with synchrotron radiation with a photon energy of 70 keV. The\nelectron density profiles perpendicular to the surface of the aqueous subphase\nhave been reconstructed from reflectometry data within a model approach to the\nstructure of an interface with two and three layers. These profiles indicate\nthe existence of a wide diffuse polymer layer 150+/-40 Angstrom in width at the\ninterface of the monolayer in both the liquid expanded and liquid condensed\nstates. A decrease in the area per molecule in the monolayer by a factor of 2\nresults in the doubling of the surface density of the macromolecule film. The\nadsorption of the polymer also affects the integral density of the layer of\npolar phospholipid groups, which decreases by a factor of ~ 2 in the liquid\nexpanded phase and by ~ 30% in the liquid condensed phase.",
        "positive": "Influence of pore dielectric boundaries on the translocation barrier of\n  DNA: We investigate the impact of dielectric boundary forces on the translocation\nprocess of charged rigid DNA segments through solid neutral nanopores. We\nassess the electrostatic contribution to the translocation free energy barrier\nof a model DNA segment by evaluating the potential of mean force in absence and\npresence of polarization effects by means of coarse-grained molecular dynamics\nsimulations. The effect of induced polarization charges has been taken into\naccount by employing ICC*, a recently developed algorithm that can efficiently\ncompute induced polarization charges induced on suitably discretized dielectric\nboundaries. Since water has a higher dielectric constant than the pore walls,\npolarization effects repel charged objects in the vicinity of the interface,\nwith the effect of significantly increasing the free energy barrier. Another\ninvestigated side effect is the change of the counterion distribution around\nthe charged polymer in presence of the induced pore charges. Furthermore we\ninvestigate the influence of adding salt to the solution."
    },
    {
        "anchor": "A detailed field theory for RNA-like molecules with periodic base\n  sequence: This work examines a field theory for RNA-like molecules in a good solvent.\nThe field theory is based on a lattice model for single- and double-strand RNA\nwith a periodic base sequence, and otherwise contains all known relevant\ndetails (polymer types, polymer lengths and interactions). As for the somewhat\nless explicit $O\\left(n\\right)$-symmetric model there is a close relation to\nthe conventional one-component branched polymer and the associated Lee-Yang\nproblem. We further elucidate this relation. We derive exact results in the\nlimiting cases of nearly complete denaturation and nearly complete\nrenaturation. The single-strand critical exponent $\\nu_{\\varphi}$ is calculated\nin two-loop order.",
        "positive": "DNA driven self-assembly of micron-sized rods using DNA-grafted\n  bacteriophage fd virions: We have functionalized the sides of fd bacteriophage virions with\noligonucleotides to induce DNA hybridization driven self-assembly of high\naspect ratio filamentous particles. Potential impacts of this new structure\nrange from an entirely new building block in DNA origami structures, inclusion\nof virions in DNA nanostructures and nanomachines, to a new means of adding\nthermotropic control to lyotropic liquid crystal systems. A protocol for\nproducing the virions in bulk is reviewed. Thiolated oligonucleotides are\nattached to the viral capsid using a heterobifunctional chemical linker. A\ncommonly used system is utilized, where a sticky, single-stranded DNA strand is\nconnected to an inert double-stranded spacer to increase inter-particle\nconnectivity. Solutions of fd virions carrying complementary strands are mixed,\nannealed, and their aggregation is studied using dynamic light scattering\n(DLS), fluorescence microscopy, and atomic force microscopy (AFM). Aggregation\nis clearly observed on cooling, with some degree of local order, and is\nreversible when temperature is cycled through the DNA hybridization transition."
    },
    {
        "anchor": "Entangled-like Chain Dynamics in Non-entangled Polymer Blends with Large\n  Dynamic Asymmetry: We discuss simulations of a simple model for polymer blends in the framework\nof the Rouse model. At odds with standard predictions, large dynamic asymmetry\nbetween the two components induces strong non-exponentiality of the Rouse modes\nfor the fast component. Despite chains being much shorter than the entanglement\nlength, it also induces dynamic features resembling a crossover to\nentangled-like chain dynamics. This unusual behavior is associated to strong\nmemory effects which break down the assumption of time uncorrelation of the\nexternal forces acting on the tagged chain.",
        "positive": "Stimuli-responsive behavior of PNiPAm microgels under interfacial\n  confinement: The volume phase transition of microgels is one of the most paradigmatic\nexamples of stimuli-responsiveness, enabling a collapse from a highly swollen\nmicrogel state into a densely coiled state by an external stimulus. Although\nwell characterized in bulk, it remains unclear how the phase transition is\naffected by the presence of a confining interface. Here, we demonstrate that\nthe temperature-induced volume phase transition of poly(N-isopropylacrylamide)\nmicrogels, conventionally considered an intrinsic molecular property of the\npolymer, is in fact largely suppressed when the microgel is adsorbed to an\nair/liquid interface. We further observe a hysteresis in core morphology and\ninterfacial pressure between heating and cooling cycles. Our results, supported\nby molecular dynamics simulations, reveal that the dangling polymer chains of\nmicrogel particles, spread at the interface under the influence of surface\ntension, do not undergo any volume phase transition, demonstrating that the\nbalance in free energy responsible for the volume phase transition is\nfundamentally altered by interfacial confinement. These results imply that\nimportant technological properties of such systems, including the\ntemperature-induced destabilization of emulsions does not occur via a decrease\nin interfacial coverage of the microgels."
    },
    {
        "anchor": "Numerical simulations of stick percolation: Application to the study of\n  structured magnetorheologial elastomers: In this article we explore how structural parameters of composites filled\nwith one-dimensional, electrically conducting elements (such as sticks,\nneedles, chains, or rods) affect the percolation properties of the system. To\nthis end, we perform Monte Carlo simulations of asymmetric two-dimensional\nstick systems with anisotropic alignments. We compute the percolation\nprobability functions in the direction of preferential orientation of the\npercolating objects and in the orthogonal direction, as functions of the\nexperimental structural parameters. Among these, we considered the average\nlength of the sticks, the standard deviation of the length distribution, and\nthe standard deviation of the angular distribution. We developed a computer\nalgorithm capable of reproducing and verifying known theoretical results for\nisotropic networks and which allows us to go beyond and study anisotropic\nsystems of experimental interest. Our research shows that the total electrical\nanisotropy, considered as a direct consequence of the percolation anisotropy,\ndepends mainly on the standard deviation of the angular distribution and on the\naverage length of the sticks. A conclusion of practical interest is that we\nfind that there is a wide and well-defined range of values for the mentioned\nparameters for which it is possible to obtain reliable anisotropic percolation\nunder relatively accessible experimental conditions when considering composites\nformed by dispersions of sticks, oriented in elastomeric matrices.",
        "positive": "Force-Velocity Relations of a Two-State Crossbridge Model for Molecular\n  Motors: We discuss the force-velocity relations obtained in a two-state crossbridge\nmodel for molecular motors. They can be calculated analytically in two limiting\ncases: for a large number and for one pair of motors. The effect of the\nstrain-dependent detachment rate on the motor characteristics is studied. It\ncan lead to linear, myosin-like, kinesin-like and anomalous curves. In\nparticular, we specify the conditions under which oscillatory behavior may be\nfound."
    },
    {
        "anchor": "Nonequilibrium Fluctuation Relation for Sheared Micellar Gel in a Jammed\n  State: We show that the shear rate at a fixed shear stress in a micellar gel in a\njammed state exhibits large fluctuations, showing positive and negative values,\nwith the mean shear rate being positive. The resulting probability distribution\nfunctions (PDF's) of the global power flux to the system vary from Gaussian to\nnon-Gaussian, depending on the driving stress and in all cases show similar\nsymmetry properties as predicted by Gallavotti-Cohen steady state fluctuation\nrelation. The fluctuation relation allows us to determine an effective\ntemperature related to the structural constraints of the jammed state. We have\nmeasured the stress dependence of the effective temperature. Further,\nexperiments reveal that the effective temperature and the standard deviation of\nthe shear rate fluctuations increase with the decrease of the system size.",
        "positive": "Waiting-time dependent non-equilibrium phase diagram of simple glass-\n  and gel-forming liquids: Under many circumstances many soft and hard materials are present in a\npuzzling wealth of non-equilibrium amorphous states, whose properties are not\nstationary and depend on preparation. They are often summarized in\nunconventional \"phase diagrams\" that exhibit new \"phases\" and/or \"transitions\",\nin which the time, however, is an essential variable. This work proposes a\nsolution to the problem of theoretically defining and predicting these\nnon-equilibrium phases and their time-evolving phase diagrams, given the\nunderlying molecular interactions. We demonstrate that these non-equilibrium\nphases and the corresponding non-stationary (i.e., aging) phase diagrams can\nindeed be defined and predicted using the kinetic perspective of a novel\nnon-equilibrium statistical mechanical theory of irreversible processes. This\nis illustrated with the theoretical description of the transient process of\ndynamic arrest into non-equilibrium amorphous solid phases, of an\ninstantaneously-quenched simple model fluid involving repulsive hard-sphere\nplus attractive square well pair interactions."
    },
    {
        "anchor": "Unfolding the Sulcus: Sulci are localized furrows on the surface of soft materials that form by a\ncompression-induced instability. We unfold this instability by breaking its\nnatural scale and translation invariance, and compute a limiting bifurcation\ndiagram for sulcfication showing that it is a scale-free, sub-critical {\\em\nnonlinear} instability. In contrast with classical nucleation, sulcification is\n{\\em continuous}, occurs in purely elastic continua and is structurally stable\nin the limit of vanishing surface energy. During loading, a sulcus nucleates at\na point with an upper critical strain and an essential singularity in the\nlinearized spectrum. On unloading, it quasi-statically shrinks to a point with\na lower critical strain, explained by breaking of scale symmetry. At\nintermediate strains the system is linearly stable but nonlinearly unstable\nwith {\\em no} energy barrier. Simple experiments confirm the existence of these\ntwo critical strains.",
        "positive": "Filling and wetting transitions on sinusoidal substrates: a mean-field\n  study of the Landau-Ginzburg model: We study the interfacial phenomenology of a fluid in contact with a\nmicrostructured substrate within the mean-field approximation. The sculpted\nsubstrate is a one-dimensional array of infinitely long grooves of sinusoidal\nsection of periodicity length L and amplitude A. The system is modelled using\nthe Landau-Ginzburg functional, with fluid-substrate couplings which correspond\nto either first-order or critical wetting for a flat substrate. We investigate\nthe effect of the roughness of the substrate in the interfacial phenomenology,\npaying special attention to filling and wetting phenomena, and compare the\nresults with the predictions of the macroscopic and interfacial Hamiltonian\ntheories. At bulk coexistence, for values of L much larger than the bulk\ncorrelation, we observe first-order filling transitions between dry and\npartially filled interfacial states, which extend off-coexistence, ending at a\ncritical point; and wetting transitions between partially filled and completely\nwet interfacial states with the same order as for the flat substrate (if\nfirst-order, wetting extends off-coexistence in a prewetting line). On the\nother hand, if the groove height is of order of the correlation length, only\nwetting transitions between dry and complete wet states are observed. However,\ntheir characteristics depend on the order of the wetting transition for the\nflat substrate. So, if it is first-order, the wetting transition temperature\nfor the rough substrate is reduced with respect to the wetting transition\ntemperature for a flat substrate, and coincides with the Wenzel law prediction\nfor very shallow substrates. On the contrary, if the flat substrate wetting\ntransition is continuous, the roughness does not change the wetting\ntemperature."
    },
    {
        "anchor": "Closely piling up of multiple adhesive fronts in adhesive friction due\n  to re-attachment: To understand why the adhesive frictional force was in linear proportion to\nthe real contact area in experiments, we investigate the adhesive friction\ngenerated by sliding elastic solids adhered to a rigid surface via multiple\nadhesive springs. Our results indicate that the shear-off force of the\ninterface increases with the energetically guided re-attachment rate of\nadhesive springs, reaching saturation at high re-attachment rates. Remarkably,\nthis shear-off force can surpass the predictions made by the fracture theory.\nBy plotting the adhesive forces along the interface, we observe substantial\nhigh adhesive forces distributed throughout the interface, based on which we\nidentify multiple adhesive fronts closely piling up along the interface. These\nregions can exhibit similar force profiles, and their number appears to\nincrease with the size of the interface, leading to a linear increase in the\ncalculated shear-off force with the size of the interface. We then suggest that\nmultiple adhesive fronts closely pile up to back up each other in adhesive\nfriction due to re-attachments, which may provide profound insights into\nunderstanding the observed phenomena associated with adhesive friction along an\ninterface.",
        "positive": "A systematic Monte Carlo simulation study of the primitive model\n  electrical double layer over an extended range of concentrations, electrode\n  charges, cation diameters and valences: The purpose of this study is to provide data for the primitive model of the\nelectrical double layer, where ions are modeled as charged hard spheres, the\nsolvent as an implicit dielectric background (with dielectric constant\n$\\epsilon= 78.5$), and the electrode as a smooth, uniformly charged, hard wall.\nWe use canonical and Grand Canonical Monte Carlo simulations to compute the\nconcentration profiles, from which the electric field and electrostatic\npotential profiles are obtained by solving Poisson's equation. We report data\nfor an extended range of parameters including 1:1, 2:1, and 3:1 electrolytes at\nconcentrations $c=0.0001-1$ M near electrodes carrying surface charges up to\n$\\sigma=\\pm 0.5$ Cm$^{-2}$. The anions are monovalent with a fixed diameter\n$d_{-}=3$ {\\AA}, while the charge and diameter of cations are varied in the\nrange $z_{+}=1$, 2, 3 and $d_{+}=1.5$, 3, 6, and 9 {\\AA} (the temperature is\n$298.15$ K). We provide all the raw data in the Supporting Information."
    },
    {
        "anchor": "Tunable corrugated patterns in an active gel sheet: Active matter locally converts chemical energy into mechanical work and, for\nthis reason, it provides new mechanisms of pattern formation. In particular,\nactive gels made of protein motors and filaments are far-from-equilibrium\nsystems that exhibit spontaneous flow,[Kruse2004, Voituriez2005] leading to\nactive turbulence in two and three dimensions[Sanchez2012, Kumar2018] and\ncoherent flow in three dimensions[Wu2017] (3D). Although these dynamic flows\nreveal a characteristic length scale resulting from the interplay between\nactive forcing and passive restoring forces, the observation of static and\nlong-range spatial patterns in active gels has remained elusive. In this work,\nwe demonstrate that a 2D free-standing nematic active gel, formed spontaneously\nby depletion forces from a 3D solution of kinesin motors and microtubule\nfilaments, actively buckles out-of-plane into a centimeter-sized periodic\ncorrugated sheet that is stable for several days at low activity. Importantly,\nthe corrugations are formed in the absence of flow and their wavelength and\nstability are controlled by the motor concentration, in agreement with a\nhydrodynamic theory. At higher activities these patterns are transient with the\ngel becoming turbulent at longer times. Our results underline the importance of\nboth passive and active forces in shaping active gels and indicate that a\nstatic material can be sculpted through an active mechanism.",
        "positive": "Electrostatic interactions between charge regulated spherical macroions: We study the interaction between two charge regulating spherical macroions\nwith dielectric interior and dissociable surface groups immersed in a\nmonovalent electrolyte solution. The charge dissociation is modelled via the\nFrumkin-Fowler-Guggenheim isotherm, which allows for multiple adsorption\nequilibrium states. The interactions are derived from the solutions of the\nmean-field Poisson-Boltzmann type theory with charge regulation boundary\nconditions. For a range of conditions we find symmetry breaking transitions\nfrom symmetric to asymmetric charge distribution exhibiting annealed charge\npatchiness, which results in like-charge attraction even in a univalent\nelectrolyte -- thus fundamentally modifying the nature of electrostatic\ninteractions in charge-stabilized colloidal suspensions."
    },
    {
        "anchor": "Moir\u00e9-pattern evolution couples rotational and translational friction\n  at crystalline interfaces: The sliding motion of objects is typically governed by their friction with\nthe underlying surface. Compared to translational friction, however, rotational\nfriction has received much less attention. Here, we experimentally and\ntheoretically study the rotational depinning and orientational dynamics of\ntwo-dimensional colloidal crystalline clusters on periodically corrugated\nsurfaces in the presence of magnetically exerted torques. We demonstrate that\nthe traversing of locally commensurate areas of the moir\\'e pattern through the\nedges of clusters, which is hindered by potential barriers during cluster\nrotation, controls its rotational depinning. The experimentally measured\ndepinning thresholds as a function of cluster size strikingly collapse onto a\nuniversal theoretical curve which predicts the possibility of a\nsuperlow-static-torque state for large clusters. We further reveal a\ncluster-size-independent rotation-translation depinning transition when\nlattice-matched clusters are driven jointly by a torque and a force. Our work\nprovides guidelines to the design of nanomechanical devices that involve\nrotational motions on atomic surfaces.",
        "positive": "Anomalous Dynamic Scaling in Locally-Conserved Coarsening of Fractal\n  Clusters: We report two-dimensional phase-field simulations of locally-conserved\ncoarsening dynamics of random fractal clusters with fractal dimension D=1.7 and\n1.5. The correlation function, cluster perimeter and solute mass are measured\nas functions of time. Analyzing the correlation function dynamics, we identify\ntwo different time-dependent length scales that exhibit power laws in time. The\nexponents of these power laws are independent of D, one of them is apparently\nthe classic exponent 1/3. The solute mass versus time exhibits dynamic scaling\nwith a D-dependent exponent, in agreement with a simple scaling theory."
    },
    {
        "anchor": "Repulsion Between Finite Charged Plates with Strongly Overlapped\n  Electric Double Layers: The screened Coulomb interaction between uniformly charged flat plates is\nconsidered at very small plate separations for which the Debye layers are\nstrongly overlapped, in the limit of small electrical potentials. If the plates\nare of infinite length, the disjoining pressure between the plates decays as an\ninverse power of the plate separation. If the plates are of finite length, we\nshow that screening Debye layer charges close to the edge of the plates are no\nlonger constrained to stay between the plates, but instead spill out into the\nsurrounding electrolyte. The resulting reduction in the disjoining pressure is\ncalculated analytically. A similar reduction of disjoining pressure due to loss\nof lateral confinement of the Debye layer charges should occur whenever the\nsizes of the interacting charged objects become small enough to approach the\nDebye scale. We investigate the effect here in the context of a two dimensional\nmodel problem that is sufficiently simple to yield analytical results.",
        "positive": "Collective modes and thermodynamics of the liquid state: Strongly interacting, dynamically disordered and with no small parameter,\nliquids took a theoretical status between gases and solids. We review different\napproaches to liquids and propose that liquids do not need classifying in terms\nof their proximity to gases and solids. Instead, they are a unique system in\ntheir own class with a notably mixed dynamical state in contrast to pure\ndynamical states of solids and gases. We start with explaining how the\nfirst-principles approach to liquids is an intractable, exponentially complex\nproblem of coupled non-linear oscillators with bifurcations. This is followed\nby a reduction of the problem based on liquid relaxation time $\\tau$\nrepresenting non-perturbative treatment of strong interactions. On the basis of\n$\\tau$, solid-like high-frequency modes are predicted and we review related\nrecent experiments. We demonstrate how these modes can be derived by\ngeneralizing either hydrodynamic or elasticity equations. We comment on the\nhistorical trend to approach liquids using hydrodynamics and compare it to an\nalternative solid-like approach. We subsequently discuss how collective modes\nevolve with temperature and how this affects liquid energy and other properties\nsuch as fast sound. Here, our emphasis is on real, rather than model, liquids.\nHighlighting the dominant role of high-frequency modes for liquid energy, we\nreview a wide range of liquids: subcritical low-viscous liquids, supercritical\nstate with two different dynamical and thermodynamic regimes separated by the\nFrenkel line, highly-viscous liquids and liquid-glass transition. We also\ndiscuss liquid-liquid phase transitions where the solid-like properties of\nliquids have become further apparent. We then discuss gas-like and solid-like\napproaches to quantum liquids and persisting theoretical problems. We list\nareas where interesting insights may appear and continue the extraordinary\nliquid story."
    },
    {
        "anchor": "An alternative scenario for the formation of specialized protein\n  nano-domains (cluster phases) in biomembranes: We discuss a realistic scenario, accounting for the existence of\nsub-micrometric protein domains in cell membranes. At the biological level,\nsuch membrane domains have been shown to be specialized, in order to perform a\ndetermined biological task, in the sense that they gather one or a few protein\nspecies out of the hundreds of different ones that a cell membrane may contain.\nBy analyzing the balance between mixing entropy and protein affinities, we\npropose that such protein sorting in distinct domains can be explained without\nappealing to pre-existing lipidic micro-phase separations, as in the lipid raft\nscenario. We show that the proposed scenario is compatible with known physical\ninteractions between membrane proteins, even if thousands of different species\ncoexist.",
        "positive": "Frustration of the isotropic-columnar phase transition of colloidal hard\n  platelets by a transient cubatic phase: Using simulations and theory, we show that the cubatic phase is metastable\nfor three model hard platelets. The locally favored structures of perpendicular\nparticle stacks in the fluid prevent the formation of the columnar phase\nthrough geometric frustration resulting in vitrification. Also, we find a\ndirect link between structure and dynamic heterogeneities in the cooperative\nrotation of particle stacks, which is crucial for the devitrification process.\nFinally, we show that the life time of the glassy cubatic phase can be tuned by\nsurprisingly small differences in particle shape."
    },
    {
        "anchor": "Tuning by pruning: exploiting disorder for global response and the\n  principle of bond-level independence: We exploit the intrinsic difference between disordered and crystalline solids\nto create systems with unusual and exquisitely tuned mechanical properties. To\ndemonstrate the power of this approach, we design materials that are either\nvirtually incompressible or completely auxetic. Disordered networks can be\nefficiently driven to these extreme limits by removing a very small fraction of\nbonds via a selected-bond removal procedure that is both simple and\nexperimentally relevant. The procedure relies on the nearly complete absence of\nany correlation between the contributions of an individual bond to different\nelastic moduli. A new principle unique to disordered solids underlies this lack\nof correlation: independence of bond-level response.",
        "positive": "Non-local effects reflect the jamming criticality in granular flows of\n  frictionless particles: The jamming transition is accompanied by a rich phenomenology, such as\nhysteresis or non-local effects, which is still not well understood. Here we\nexperimentally investigate a model frictionless granular layer flowing down an\ninclined plane, as a way to disentangle generic collective effects from those\narising from frictional interactions. We find that thin frictionless granular\nlayers are devoid of hysteresis, yet the layer stability is increased as it\ngets thinner. Rheological laws obtained for different layer thicknesses can be\ncollapsed into a unique master curve, supporting that non-local effects are the\nconsequence of the usual finite-size effects associated to the presence of a\ncritical point. This collapse indicates that the so-called isostatic length\n$l^*$ governs the effect of boundaries on flow, and rules out other\npropositions made in the past."
    },
    {
        "anchor": "Collective behavior of active topological solitons, knotted streamlines,\n  and transport of cargo in liquid crystals: Active colloids and liquid crystals are capable of locally converting the\nmacroscopically-supplied energy into directional motion and promise a host of\nnew applications, ranging from drug delivery to cargo transport at the\nmesoscale. Here we uncover how topological solitons in liquid crystals can\nlocally transform electric energy to translational motion and allow for the\ntransport of cargo along directions dependent on frequency of the applied\nelectric field. By combining polarized optical video microscopy and numerical\nmodeling that reproduces both the equilibrium structures of solitons and their\ntemporal evolution in applied fields, we uncover the physical underpinnings\nbehind this reconfigurable motion and study how it depends on the structure and\ntopology of solitons. We show that, unexpectedly, the directional motion of\nsolitons with and without the cargo arises mainly from the asymmetry in\nrotational dynamics of molecular ordering in liquid crystal rather than from\nthe asymmetry of fluid flows, as in conventional active soft matter systems.",
        "positive": "Renormalized spectrum of quasiparticle in limited number of states,\n  strongly interacting with two-mode polarization phonons at $T=0$ K: Within unitary transformed Hamiltonian of Fr\\\"ohlich type, using the Green's\nfunctions method, exact renormalized energy spectrum of quasiparticle strongly\ninteracting with two-mode polarization phonons is obtained at $T=0$ K in a\nmodel of the system with limited number of its initial states. Exact analytical\nexpressions for the average number of phonons in ground state and in all\nsatellite states of the system are presented. Their dependences on a magnitude\nof interaction between quasiparticle and both phonon modes are analyzed."
    },
    {
        "anchor": "Nano-Confinement Effects on Liquid Pressure: In this work, molecular dynamics simulations are performed to estimate the\nequilibrium pressure of liquid confined in nanopores. The simulations show that\nthe pressure is highly sensitive to the pore size and can significantly change\nfrom absolute positive to negative values for a very small (0.1 nm) change in\npore size. The contribution from the solid-liquid interaction always dominates\nthe pressure in the first liquid layer adjacent to the surface and the\nsensitiveness of pressure on the pore size is due to the atom distribution in\nthe liquid layers. A surface influence number S is introduced to quantitatively\ncharacterize the degree of the confinement. The S number decreases with\nincreasing pore size based on a power law function at constant system\ntemperature. In nanopores with large S number, the pore liquid pressure is\nfound to be independent of bulk liquid pressure while the pore pressure\nincreases with bulk pressure in nanopores with small S number.",
        "positive": "Surface tension and the Mori-Tanaka theory of non-dilute soft composite\n  solids: Eshelby's theory is the foundation of composite mechanics, allowing\ncalculation of the effective elastic moduli of composites from a knowledge of\ntheir microstructure. However it ignores interfacial stress and only applies to\nvery dilute composites -- i.e. where any inclusions are widely spaced apart.\nHere, within the framework of the Mori-Tanaka multiphase approximation scheme,\nwe extend Eshelby's theory to treat a composite with interfacial stress in the\nnon-dilute limit. In particular we calculate the elastic moduli of composites\ncomprised of a compliant, elastic solid hosting a non-dilute distribution of\nidentical liquid droplets. The composite stiffness depends strongly on the\nratio of the droplet size, $R$, to an elastocapillary length scale, $L$.\nInterfacial tension substantially impacts the effective elastic moduli of the\ncomposite when $R/L\\lesssim 100$. When $R < 3L/2$ ($R=3L/2$) liquid inclusions\nstiffen (cloak the far-field signature of) the solid."
    },
    {
        "anchor": "Aggregates of two-dimensional vesicles: Rouleaux and sheets: Using both numerical and variational minimization of the bending and adhesion\nenergy of two-dimensional lipid vesicles, we study their aggregation, and we\nfind that the stable aggregates include an infinite number of vesicles and that\nthey arrange either in a columnar or in a sheet-like structure. We calculate\nthe stability diagram and we discuss the modes of transformation between the\ntwo types of aggregates, showing that they include disintegration as well as\nintercalation.",
        "positive": "Activity Driven Phase Separation and Ordering Kinetics of Passive\n  Particles: The steady state and phase ordering kinetics in a pure active Borwnian\nparticle system are studied in recent years. In binary mixture of active and\npassive Brownian particles passive particles are used as probe to understand\nthe properties of active medium. In our present study we study the mixture of\npassive and active Brownian particles. Here we aim to understand the steady\nstate and kinetics of small passive particles in the mixture. In our system,the\npassive particles are small in size and large in number, whereas ABPs are large\nin size and small in number. The system is studied on a two-dimensional\nsubstrate using overdamp Langevin dynamic simulation. The steady state and\nkinetics of passive particles are studied for various size and activity of\nactive particles. Passive particles are purely athermal in nature and have\ndynamics only due to bigger ABPs. For small size ratio and activity the passive\nparticles remain homogeneous in the system, whereas on increasing size ratio\nand activity they form periodic hexagonal close pack (HCP) spanning clusters in\nthe system. We have also studied the kinetics of growing passive particle\nclusters. The mass of the largest cluster shows a much slower growth kinetics\nin contrast to conserved growth kinetics in ABP system. Our study provides an\nunderstanding of steady state and kinetics of passive particles in the presence\nof bigger active particles. The mixture can be thought of as effect of big\nmicroorganism moving in passive medium."
    },
    {
        "anchor": "Active motion of tangentially-driven polymers in periodic array of\n  obstacles: We computationally investigate the active transport of tangentially-driven\npolymers with varying degrees of flexibility and activity in two-dimensional\nsquare lattices of obstacles. Tight periodic confinement induces notable\nconformational changes and distinct modes of transport for flexible and stiff\nactive filaments. It leads to localization and caging of flexible polymers\ninside the inter-obstacle pores, while promoting more elongated conformations\nand enhanced diffusion for stiff polymers at low to moderate activity levels.\nThe migration of flexible active polymers occurs via hopping events, where they\nunfold to move from one cage to another. In contrast, stiff chains travel\nmainly in straight paths within inter-obstacle channels, while occasionally\nchanging their direction of motion. Both the duration of caging and persistent\ndirected migration within the channels decrease with increasing the activity\nlevel. As a consequence, at high active forces polymers overcome confinement\neffects and transport within inter-obstacle pores as swiftly as those in free\nspace. We explain the center of mass dynamics of semiflexible polymers in terms\nof active force and obstacle packing fraction by developing an approximate\nanalytical theory.",
        "positive": "Using force covariance to derive effective stochastic interactions in\n  dissipative particle dynamics: There exist methods for determining effective conservative interactions in\ncoarse grained particle based mesoscopic simulations. The resulting models can\nbe used to capture thermal equilibrium behavior, but in the model system we\nstudy do not correctly represent transport properties. In this article we\nsuggest the use of force covariance to determine the full functional form of\ndissipative and stochastic interactions. We show that a combination of the\nradial distribution function and a force covariance function can be used to\ndetermine all interactions in dissipative particle dynamics. Furthermore we use\nthe method to test if the effective interactions in dissipative particle\ndynamics (DPD) can be adjusted to produce a force covariance consistent with a\nprojection of a microscopic Lennard-Jones simulation. The results indicate that\nthe DPD ansatz may not be consistent with the underlying microscopic dynamics.\nWe discuss how this result relates to theoretical studies reported in the\nliterature."
    },
    {
        "anchor": "Two-state protein-like folding of a homopolymer chain: Many small proteins fold via a first-order \"all-or-none\" transition directly\nfrom an expanded coil to a compact native state. Here we study an analogous\ndirect freezing transition from an expanded coil to a compact crystallite for a\nsimple flexible homopolymer. Wang-Landau sampling is used to construct the 1D\ndensity of states for square-well chains of length 128. Analysis within both\nthe micro-canonical and canonical ensembles shows that, for a chain with\nsufficiently short-range interactions, the usual polymer collapse transition is\npreempted by a direct freezing or \"folding\" transition. A 2D free-energy\nlandscape, built via subsequent multi-canonical sampling, reveals a dominant\nfolding pathway over a single free-energy barrier. This barrier separates a\nhigh entropy ensemble of unfolded states from a low entropy set of crystallite\nstates and the transition proceeds via the formation of a transition-state\nfolding nucleus. Despite the non-unique homopolymer ground state, the\nthermodynamics of this direct freezing transition are identical to the\nthermodynamics of two-state protein folding. The model chain satisfies the\nvan't Hoff calorimetric criterion for two-state folding and an Arrhenius\nanalysis of the folding/unfolding free energy barrier yields a Chevron plot\ncharacteristic of small proteins.",
        "positive": "Modelling structural relaxation in polymeric glasses using the\n  aggregation-fragmentation concept: Governing equations are derived for the kinetics of physical aging in\npolymeric glasses. An amorphous polymer is treated as an ensemble of\ncooperatively rearranged regions (CRR). Any CRR is thought of as a string of\nelementary clusters (EC). Fragmentation of the string may occur at random time\nat any border between ECs. Two string can aggregate at random time to produce a\nnew string. The processes of aggregation and fragmentation are treated as\nthermally activated, and the rate of fragmentation is assumed to grow with\ntemperature more rapidly than that for coalescence. This implies that only\nelementary clusters are stable at the glass transition temperature, whereas\nbelow this temperature, CRRs containing several ECs remain stable as well. A\nnonlinear differential equation is developed for the distribution of CRRs with\nvarious numbers of ECs. Adjustable parameters of the model are found by fitting\nexperimental data in calorimetric tests for polycarbonate, poly(methyl\nmethacrylate), polystyrene and poly(vinyl acetate). For all materials, fair\nagreement is established between observations and results of numerical\nsimulation. For PVAc, the relaxation spectrum found by matching data in a\ncalorimetric test is successfully employed to predict experimental data in a\nshear relaxation test."
    },
    {
        "anchor": "The colloidal nature of complex fluids leads to enhanced motility of\n  flagellated bacteria: The natural habitats of microorganisms in the human microbiome and ocean and\nsoil ecosystems are full of colloids and macromolecules, which impart\nnon-Newtonian flow properties drastically affecting the locomotion of swimming\nmicroorganisms. Although the low-Reynolds-number hydrodynamics of the swimming\nof flagellated bacteria in simple Newtonian fluids has been well developed, our\nunderstanding of bacterial motility in complex non-Newtonian fluids is still\nprimitive. Even after six decades of research, fundamental questions about the\nnature and origin of bacterial motility enhancement in polymer solutions are\nstill under debate. Here, we study the motility of flagellated bacteria in\ncolloidal suspensions of varying sizes and volume fractions. We find that\nbacteria in dilute colloidal suspensions display quantitatively the same motile\nbehaviors as those in dilute polymer solutions, where a universal\nparticle-size-dependent motility enhancement up to 80% is uncovered,\naccompanied by strong suppression of bacterial wobbling. By virtue of the\nwell-controlled size and the hard-sphere nature of colloids, the finding not\nonly resolves the long-standing controversy over bacterial motility enhancement\nin complex fluids but also challenges all the existing theories using polymer\ndynamics to address the swimming of flagellated bacteria in dilute polymer\nsolutions. We further develop a simple physical model incorporating the\ncolloidal nature of complex fluids, which quantitatively explains bacterial\nwobbling dynamics and mobility enhancement in both colloidal and polymeric\nfluids. Our study sheds light on the puzzling motile behaviors of bacteria in\ncomplex fluids relevant to a wide range of microbiological processes and\nprovides a cornerstone in engineering bacterial swimming in complex\nenvironments.",
        "positive": "Effective Area-Elasticity and Tension of Micro-manipulated Membranes: We evaluate the effective Hamiltonian governing, at the optically resolved\nscale, the elastic properties of micro-manipulated membranes. We identify\nfloppy, entropic-tense and stretched-tense regimes, representing different\nbehaviors of the effective area-elasticity of the membrane. The corresponding\neffective tension depends on the microscopic parameters (total area, bending\nrigidity) and on the optically visible area, which is controlled by the imposed\nexternal constraints. We successfully compare our predictions with recent data\non micropipette experiments."
    },
    {
        "anchor": "Microfluidic Pumping by Micromolar Salt Concentrations: An ion-exchange-resin-based microfluidic pump is introduced that utilizes\ntrace amounts of ions to generate fluid flows. We show experimentally that our\npump operates in almost deionized water for periods exceeding 24h and induces\nfluid flows of um/s over hundreds of um. This flow displays a far-field,\npower-law decay which is characteristic of two-dimensional (2D) flow when the\nsystem is strongly confined and of three-dimensional (3D) flow when it is not.\nUsing theory and numerical calculations we demonstrate that our observations\nare consistent with electroosmotic pumping driven by umol/L ion concentrations\nin the sample cell that serve as 'fuel' to the pump. Our study thus reveals\nthat trace amounts of charge carriers can produce surprisingly strong fluid\nflows; an insight that should benefit the design of a new class of microfluidic\npumps that operate at very low fuel concentrations.",
        "positive": "Electric-field-induced turbulent energy cascade in an oil-in-oil\n  emulsion: We observe electro-hydrodynamically driven turbulent flows at low Reynolds\nnumbers in a two-fluid emulsion consisting of micron-scale droplets. In the\npresence of electric fields, the droplets produce interacting hydrodynamic\nflows which result in a dynamical organization at a spatial scale much larger\nthan the size of the individual droplets. We characterize the dynamics\nassociated with these structures by both video imaging and a simultaneous, in\nsitu, measurement of the time variation of the bulk Reynolds stress with a\nrheometer. The results display scale invariance in the energy spectra in both\nspace and time."
    },
    {
        "anchor": "Submicrometer Pattern Fabrication by Intensification of Instability in\n  Ultrathin Polymer Films under a Water-Solvent Mix: Dewetting of ultrathin (< 100 nm) polymer films, by heating above the glass\ntransition, produces droplets of sizes of the order of microns and mean\nseparations between droplets of the order of tens of microns. These relatively\nlarge length scales are because of the weak destabilizing van der Waals forces\nand the high surface energy penalty required for deformations on small scales.\nWe show a simple, one-step versatile method to fabricate sub-micron (>~100 nm)\ndroplets and their ordered arrays by room temperature dewetting of ultrathin\npolystyrene (PS) films by minimizing these limitations. This is achieved by\ncontrolled room temperature dewetting under an optimal mixture of water,\nacetone and methyl-ethyl ketone (MEK). Diffusion of organic solvents in the\nfilm greatly reduces its glass transition temperature and the interfacial\ntension, but enhances the destabilizing field by introduction of electrostatic\nforce. The latter is reflected in a change in the exponent, n of the\ninstability length scale, {\\lambda} ~h^n, where h is the film thickness and n =\n1.51 \\pm 0.06 in the case of water-solvent mix, as opposed to its value of 2.19\n\\pm 0.07 for dewetting in air. The net outcome is more than one order of\nmagnitude reduction in the droplet size as well as their mean separation and\nalso a much faster dynamics of dewetting. We also demonstrate the use of this\ntechnique for controlled dewetting on topographically patterned substrates with\nsubmicrometer features where dewetting in air is either arrested, incomplete or\nunable to produce ordered patterns.",
        "positive": "Hidden geometry and dynamics of complex networks: Spin reversal in\n  nanoassemblies with pairwise and triangle-based interactions: Recent studies of networks representing complex systems from the brain to\nsocial graphs have revealed their higher-order architecture, which can be\ndescribed by aggregates of simplexes (triangles, tetrahedrons, and higher\ncliques). Current research aims at quantifying these hidden geometries by the\nalgebraic topology methods and deep graph theory and understanding the dynamic\nprocesses on simplicial complexes. Here, we use the recently introduced model\nfor geometrical self-assembly of cliques to grow nano-networks of triangles and\nstudy the filed-driven spin reversal processes on them. With the\nantiferromagnetic interactions between the Ising spins attached to the nodes,\nthis assembly ideally supports the geometric frustration, which is recognized\nas the origin of some new phenomena in condensed matter physics. In the\ndynamical model, a gradual switching from the pairwise to triangle-based\ninteractions is controlled by a parameter. Thus, the spin frustration effects\non each triangle give way to the mesoscopic ordering conditioned by a complex\narrangement of triangles. We show how the balance between these interactions\nchanges the shape of the hysteresis loop. Meanwhile, the fluctuations in the\naccompanying Barkhausen noise exhibit robust indicators of self-organized\ncriticality, which is induced by the network geometry alone without any\nmagnetic disorder."
    },
    {
        "anchor": "Pairing evidence of 8CB molecules adsorbed on MoS2: Influence of 2D\n  commensurability on the intralamellar structure: By combining X-ray diffraction studies under grazing incidence (GIXD) and\nScanning Tunneling Microscopy (STM) measurements, we have precisely determined\nthe structure of 8CB molecules adsorbed on MoS2, under the thick organic film.\nThe commensurability of the adsorbed network and the intracell structure have\nbeen determined, revealing a complex structure characterized by a\nnon-equivalence of adjacent lamellae with pair associations of molecules in one\nlamella over two. We have interpreted such a result by a simple model of a\nsingle lamella. This pair association in one lamella over two appears as a\ndirect evidence of the connection between the commensurabilities in the two\ndirections. The value of the molecule-substrate potential corrugations is\nparticularly high, indicating that the dipolar momentum of 8CB molecules could\nplay a fundamental role in the molecule-substrate interactions",
        "positive": "Sub-THz complex dielectric constants of smectite clay thin samples with\n  Na$^{+}$/Ca$^{++}$-ions: We implement a technique to characterize the electromagnetic properties at\nfrequencies 100 to 165 GHz (3 cm$^{-1}$ to 4.95 cm$^{-1}$) of oriented smectite\nsamples using an open cavity resonator connected to a sub-millimeter wave VNA\n(Vector Network Analyzer). We measured dielectric constants perpendicular to\nthe bedding plane on oriented Na$^{+}$ and Ca$^{++}$-ion stabilized smectite\nsamples deposited on a glass slide at ambient laboratory conditions (room\ntemperature and room light). The clay layer is much thinner ($\\sim$ 30 $\\mu$m)\nthan the glass substrate ($\\sim$ 2.18 mm). The real part of dielectric\nconstant, $\\epsilon_{re}$, is essentially constant over this frequency range\nbut is larger in Na$^{+}$- than in Ca$^{++}$-ion infused clay. The total\nelectrical conductivity (associated with the imaginary part of dielectric\nconstant, $\\epsilon_{im}$) of both samples increases monotonically at lower\nfrequencies ($<$ 110 GHz), but shows rapid increase for Na$^{+}$ ions in the\nregime $>$ 110 GHz. The dispersion of the samples display a dependence on the\nionic strength in the clay interlayers, i.e., $\\zeta$-potential in the Stern\nlayers."
    },
    {
        "anchor": "Transition to a labyrinthine phase in a driven granular medium: Labyrinthine patterns arise in two-dimensional physical systems submitted to\ncompeting interactions, ranging from the fields of solid-state physics to\nhydrodynamics. For systems of interacting particles, labyrinthine and stripe\nphases were studied in the context of colloidal particles confined into a\nmonolayer, both numerically by means of Monte Carlo simulations and\nexperimentally using superparamagnetic particles. Here we report an\nexperimental observation of a labyrinthine phase in an out-of-equilibrium\nsystem constituted of macroscopic particles. Once sufficiently magnetized, they\norganize into short chains of particles in contact and randomly orientated. We\ncharacterize the transition from a granular gas state towards a solid\nlabyrinthine phase, as a function of the ratio of the interaction strength to\nthe kinetic agitation. Spatial local structure is analyzed by means of an\naccurate particle tracking. Moreover, we explain the formation of these chains\nusing a simple model.",
        "positive": "Diffusion and viscosity of non-entangled polyelectrolytes: We report chain self-diffusion and viscosity data for sodium polystyrene\nsulfonate (NaPSS) in semidilute salt-free aqueous solutions measured by pulsed\nfield gradient NMR and rotational rheometry respectively. The observed\nconcentration dependence of $\\eta$ and $D$ are consistent with the Rouse-Zimm\nscaling model with a concentration dependent monomeric friction coefficient.\nThe concentration dependence of the monomeric friction coefficient exceeds that\nexpected from free-volume models of diffusion, and its origin remains unclear.\nCorrelation blobs and dilute chains with equivalent end-to-end distances\nexhibit nearly equal friction coefficients, in agreement with scaling. The\nviscosity and diffusion data are combined using the Rouse model to calculate\nthe chain dimensions of NaPSS in salt-free solution, these agree quantitatively\nwith SANS measurements."
    },
    {
        "anchor": "Elasticity and Fluctuations of Frustrated Nano-Ribbons: We derive a reduced quasi-one-dimensional theory of geometrically frustrated\nelastic ribbons. Expressed in terms of geometric properties alone, it applies\nto ribbons over a wide range of scales, allowing the study of their elastic\nequilibrium, as well as thermal fluctuations. We use the theory to account for\nthe twisted-to-helical transition of ribbons with spontaneous negative\ncurvature, and the effect of fluctuations on the corresponding critical\nexponents. The persistence length of such ribbons changes non-monotonically\nwith the ribbon's width, dropping to zero at the transition. This and other\nstatistical properties qualitatively differ from those of non-frustrated\nfluctuating filaments.",
        "positive": "On the nonlocal viscosity kernel of mixtures: In this report we investigate the multiscale hydrodynamical response of a\nliquid as a function of mixture composition. This is done via a series of\nmolecular dynamics simulations where the wave vector dependent viscosity kernel\nis computed for three mixtures each with 7-15 different compositions. We\nobserve that the nonlocal viscosity kernel is dependent on composition for\nsimple atomic mixtures for all the wave vectors studied here, however, for a\nmodel polymer melt mixture the kernel is independent of composition for large\nwave vectors. The deviation from ideal mixing is also studied. Here it is shown\nthat a Lennard-Jones mixture follows the ideal mixing rule surprisingly well\nfor a large range of wave vectors, whereas for both the Kob-Andersen mixture\nand the polymer melt large deviations are found. Furthermore, for the polymer\nmelt the deviation is wave vector dependent such that there exists a critical\nlength scale at which the ideal mixing goes from under-estimating to\nover-estimating the viscosity."
    },
    {
        "anchor": "Out of Equilibrium Characteristics of a Forced Translocating Chain\n  through a Nanopore: Polymer translocation through a nano-pore in a thin membrane is studied using\na coarse-grained bead-spring model and Langevin dynamics simulation with a\nparticular emphasis to explore out of equilibrium characteristics of the\ntranslocating chain. We analyze the out of equilibrium chain conformations both\nat the $cis$ and the $trans$ side separately either as a function of the time\nduring the translocation process or as as function of the monomer index $m$\ninside the pore. A detailed picture of translocation emerges by monitoring the\ncenter of mass of the translocating chain, longitudinal and transverse\ncomponents of the gyration radii and the end to end vector. We observe that\npolymer configurations at the $cis$ side are distinctly different from those at\nthe $trans$ side. During the translocation, and immediately afterwards, the\nchain is clearly out of equilibrium, as different parts of the chain are\ncharacterized by a series of effective Flory exponents. We further notice that\nimmediately after the translocation the last set of beads that have just\ntranslocated take a relatively compact structure compared to the first set of\nbeads that translocated earlier, and the chain immediately after translocation\nis described by an effective Flory exponent $0.45 \\pm 0.01$. The analysis of\nthese results is further strengthened by looking at the conformations of chain\nsegments of equal length as they cross from the $cis$ to the $trans$ side, We\ndiscuss implications of these results to the theoretical estimates and\nnumerical simulation studies of the translocation exponent reported by various\ngroups.",
        "positive": "The Process-Directed Self-Assembly of Block Copolymer Particles: The kinetic paths of structural evolution and formation of block copolymer\n(BCP) particles are explored using dynamic self-consistent field theory\n(DSCFT). It is shown that the process-directed self-assembly of BCP immersed in\na poor solvent leads to the formation of striped ellipsoids, onion-like\nparticles and double-spiral lamellar particles. The theory predicts a\nreversible path of shape transition between onion-like particles and striped\nellipsoidal ones by regulating the temperature (related to the Flory-Huggins\nparameter between the two components of BCP, \\chi_{AB}) and the selectivity of\nsolvent toward one of the two BCP components. Furthermore, a kinetic path of\nshape transition from onion-like particles to double-spiral lamellar particles,\nand then back to onion-like particles is demonstrated. By investigating the\ninner-structural evolution of a BCP particle, it is identified that changing\nthe intermediate bi-continuous structure into a layered one is crucial for the\nformation of striped ellipsoidal particles. Another interesting finding is that\nthe formation of onion-like particles is characterized by a two-stage\nmicrophase separation. The first is induced by the solvent preference, and the\nsecond is controlled by the thermodynamics. The findings lead to an effective\nway of tailoring nanostructure of BCP particles for various industrial\napplications."
    },
    {
        "anchor": "Mean-field description of plastic flow in amorphous solids: Failure and flow of amorphous materials are central to various phenomena\nincluding earthquakes and landslides. There is accumulating evidence that the\nyielding transition between a flowing and an arrested phase is a critical\nphenomenon, but the associated exponents are not understood, even at a\nmean-field level where the validity of popular models is debated. Here we solve\na mean-field model that captures the broad distribution of the mechanical noise\ngenerated by plasticity, whose behavior is related to biased L\\'evy flights\nnear an absorbing boundary. We compute the exponent $\\theta$ characterising the\ndensity of shear transformation $P(x)\\sim x^{\\theta}$, where $x$ is the stress\nincrement beyond which they yield. We find that after an isotropic thermal\nquench, $\\theta=1/2$. However, $\\theta$ depends continuously on the applied\nshear stress, this dependence is not monotonic, and its value at the yield\nstress is not universal. The model rationalizes previously unexplained\nobservations, and captures reasonably well the value of exponents in three\ndimensions. Values of exponents in four dimensions are accurately predicted.\nThese results support that it is the true mean-field model that applies in\nlarge dimension, and raise fundamental questions on the nature of the yielding\ntransition.",
        "positive": "pH Switchable Pickering Emulsions Stabilized by Polyelectrolyte\n  Biosurfactant Complex Coacervate Colloids: Polyelectrolyte-surfactant complexes (PESCs) have long been employed as\noil-in-water (o/w) emulsions stabilizers, but never in the structure of\ncolloidal complex coacervates providing a Pickering effect. The complexed state\nof PESCs could make them unsuitable o/w Pickering emulsifiers, which instead\nrequire a balance between colloidal structure and stability, amphiphilicity and\nwettability. Here we hypothesize that PESCs coacervates are efficient Pickering\nstabilizers. Instead of classical surfactants, we employ sophorolipid (SL)\nbiosurfactants, atypical anionic/neutral stimuli-responsive biosurfactants.\nDespite their tunable charge and mild amphiphilic character, they can be used\nin combination with cationic/neutral polyelectrolytes (chitosan, CHL, or\npoly-L-lysine, PLL) to form PESC coacervates for the development of biobased,\nbut also pH-switchable, Pickering emulsions.Aqueous solutions of SL-CHL (or\nSL-PLL) complex coacervates are emulsified with dodecane. Confocal laser\nscanning microscopy (CLSM) and scanning electron microscopy under cryogenic\nconditions (cryo-SEM) demonstrate the Pickering effect, while optical\nmicroscopy and oscillatory rheology respectively assess the emulsion formation\nand relative viscoelastic properties.Both SL-CHL and SL-PLL PESCs stabilize o/w\nemulsions up to $\\Phi$oil of 0.7 only in the pH region of complex coacervation\n(6 < pH < 9): outside this range, phase separation occurs. Rheology shows a\ntypical solid-like response and mechanical recovery upon applying large\ndeformations. CLSM and cryo-SEM highlight a colloidal structure, associated to\nthe complex coacervates, of the oil/water interface and suggest a Pickering\neffect. These findings demonstrate the Pickering effect from PESC coacervates\nand the possibility to use biobased and biocompatible components, with\napplication potential in cosmetics, food science, or oil recovery."
    },
    {
        "anchor": "The Nanofluidic Confinement Apparatus: Studying confinement dependent\n  nanoparticle behavior and diffusion: We present a versatile setup for investigating the nanofluidic behavior of\nnanoparticles as a function of the gap distance between two confining surfaces.\nThe setup is designed as an open system which operates with small amounts of\ndispersion of $\\approx 20\\,\\mu$l, permits the use of coated and patterned\nsamples, and allows high-numerical-aperture microscopy access. Piezo elements\nenable 5D relative positioning of the surfaces. We achieve a parallelization of\nless than $1\\,$nm vertical deviation over a lateral distance of $10\\,\\mu$m. The\nvertical separation is tunable and detectable with subnanometer accuracy down\nto direct contact. At rest, the gap distance is stable on a nanometer level.\nUsing the tool we measure the vertical position termed height and the lateral\ndiffusion of $60\\,$nm charged Au nanospheres as a function of confinement\nbetween a glass and a polymer surface. Interferometric scattering detection\nresults in sub $10\\,$nm vertical and sub $5\\,$nm lateral particle localization\naccuracy, and a single particle illumination time below $40\\,\\mu$s. We measure\nthe height of the particles to be consistently above the gap center,\ncorresponding to a higher charge on the polymer substrate. In terms of\ndiffusion, we find a strong monotonic decay of the diffusion constant with\ndecreasing gap distance. This result cannot be explained by hydrodynamic\neffects, including the asymmetric vertical position of the particles in the\ngap. Instead we attribute it to an electroviscous effect. For strong\nconfinement of less than $120\\,$nm gap distance, we detect an onset of\nsub-diffusion which can be correlated to a motion of the particles along\nhigh-gap-distance paths.",
        "positive": "Multiple Particle Correlation Analysis of Many-Particle Systems:\n  Formalism and Application to Active Matter: We introduce a fast spatial point pattern analysis technique which is\nsuitable for systems of many identical particles giving rise to multi-particle\ncorrelations up to arbitrary order. The obtained correlation parameters allow\nto quantify the quality of mean field assumptions or theories that incorporate\ncorrelations of limited order. We study the Vicsek model of self-propelled\nparticles and create a correlation map marking the required correlation order\nfor each point in phase space incorporating up to ten-particle correlations. We\nfind that multi-particle correlations are important even in a large part of the\ndisordered phase. Furthermore, the two-particle correlation parameter serves as\nan excellent order parameter to locate both phase transitions of the system,\nwhereas two different order parameters were required before."
    },
    {
        "anchor": "Water confined in nanopores: spontaneous formation of microcavities: Molecular Dynamics simulations of water confined in nanometer sized,\nhydrophobic channels show that water forms localized cavities for pore diameter\n~ 2.0 nm. The cavities present non-spherical shape and lay preferentially\nadjacent to the confining wall inducing a peculiar form to the liquid exposed\nsurface. The regime of localized cavitation appears to be correlated with the\nformation of a vapor layer, as predicted by the Lum-Chandler-Weeks theory,\nimplying partial filling of the pore.",
        "positive": "Entanglements and Whitehead Products: Generalizing Kleman's Construction\n  to Higher-Dimensional Defects: We review the interpretation of Whitehead products in homotopy theory as an\nentanglement of topological defects in ordered media."
    },
    {
        "anchor": "Implementation of Morse-Witten theory for a polydisperse wet 2D foam\n  simulation: The Morse-Witten theory (D. Morse and T. Witten, EPL 22 (1993) 549-555)\nprovides a formulation for the inter-bubble forces and corresponding\ndeformations in a liquid foam, accurate in the limit of high liquid fraction.\nHere we show how the theory may be applied in practice, including allowing for\npolydispersity in the bubble sizes. The resulting equilibrated 2D structures\nare consistent with direct calculations, within the limitations of the theory.\nThe path to developing a 3D model is outlined for future work.",
        "positive": "Structure of Electrorheological Fluids: Specially synthesized silica colloidal spheres with fluorescent cores were\nused as model electrorheological fluids to experimentally explore structure\nformation and evolution under conditions of no shear. Using Confocal Scanning\nLaser Microscopy we measured the location of each colloid in three dimensions.\nWe observed an equilibrium body-centered tetragonal phase and several\nnon-equilibrium structures such as sheet-like labyrinths and isolated chains of\ncolloids. The formation of non-equilibrium structures was studied as a function\nof the volume fraction, electric field strength and starting configuration of\nthe colloid. We compare our observations to previous experiments, simulations\nand calculations."
    },
    {
        "anchor": "Phoretic Interactions Generically Induce Dynamic Clusters and Wave\n  Patterns in Active Colloids: We introduce a representative minimal model for phoretically interacting\nactive colloids. Combining kinetic theory, linear stability analyses, and a\ngeneral relation between self-propulsion and phoretic interactions in\nauto-diffusiophoretic and auto-thermophoretic Janus colloids collapses the\nparameter space to two dimensions: area fraction and P\\'eclet number. This\ncollapse arises when the lifetime of the self-generated phoretic fields is not\ntoo short, and leads to a universal phase diagram showing that phoretic\ninteractions {\\it generically} induce pattern formation in typical Janus\ncolloids, even at very low density. The resulting patterns include waves and\ndynamic aggregates closely resembling the living clusters found in experiments\non dilute suspension of Janus colloids.",
        "positive": "The effect of DNA conformation changes on the coupling of the\n  macromolecule deformation components: The model of the deformation of DNA macromolecule is developed with the\naccounting of two types of components of deformation: external and internal.\nExternal components describe the bend, twist and stretch of the double helix.\nThe internal component - the conformational mobility inside of the double\nhelix. In the work the deformation of DNA macromolecule is considered taking\ninto account the coupling of the external component (of deformation) with the\ninternal component (of conformational change). Under the task consideration the\nmacromolecule twist-stretch coupling and coupling between twist and internal\ncomponent are taken into account. The solution obtained in these conditions for\nthe deformation components allows changing the character of respond in stretch\ncomponent on unwind (overwind) in dependence on the applied force to twist\ncomponent. The changing of the character of deformation from compression to\ntension achieving of critical untwisting force (and vise versa the changing of\nthe character of deformation from overwind to unwind at critical tension\nforce)is known from the single molecular experiments. The nature of such\nunexpected behavior of double helix have clarified in the present work by\nincluding in consideration the internal component. The obtained solutions and\ntheir conformity to experimental results show the essential role of coupling\nbetween internal and external components in the double helix conformational\nmechanics under action force in pN range."
    },
    {
        "anchor": "Learning the Hydrophilic, Hydrophobic and Aromatic Character of Amino\n  Acids from their Interfacial Thermal Conductance in Water: In this study, the thermal relaxation of the 20 naturally occurring\namino-acids in water is investigated using transient non-equilibrium\nmolecular-dynamics simulations. By modeling the thermal relaxation process, the\nrelaxation times of the amino-acids in water occurs over a timescale covering\n2-5 ps. For the hydrophobic amino acids, the relaxation time is controlled by\nthe size of the hydrocarbon side chain, while for hydrophilic amino acids, the\nnumber of hydrogen bonds do not significantly affect the timescales of the heat\ndissipation. Our results show that the interfacial thermal conductance at the\namino-acid water interface is in the range of~40-80 MWm$^{-2}$K$^{-1}$.\nHydrophobic and aromatic amino acids tend to have a lower interfacial thermal\nconductance. Notably, we reveal that amino acids can be classified, in terms of\ntheir thermal relaxation times and molar masses, into simply connected phases\nwith the same hydrophilicity, hydrophibicity and aromaticity.",
        "positive": "Dynamics of a Semiflexible Polymer or Polymer Ring in Shear Flow: Polymers exposed to shear flow exhibit a rich tumbling dynamics. While rigid\nrods rotate on Jeffery orbits, flexible polymers stretch and coil up during\ntumbling. Theoretical results show that in both of these asymptotic regimes the\ntumbling frequency f_c in a linear shear flow of strength \\gamma scales as a\npower law Wi^(2/3) in the Weissenberg number Wi=\\gamma \\tau, where \\tau is a\ncharacteristic time of the polymer's relaxational dynamics. For flexible\npolymers these theoretical results are well confirmed by experimental single\nmolecule studies. However, for the intermediate semiflexible regime the\nsituation is less clear. Here we perform extensive Brownian dynamics\nsimulations to explore the tumbling dynamics of semiflexible polymers over a\nbroad range of shear strength and the polymer's persistence length l_p. We find\nthat the Weissenberg number alone does not suffice to fully characterize the\ntumbling dynamics, and the classical scaling law breaks down. Instead, both the\npolymer's stiffness and the shear rate are relevant control parameters. Based\non our Brownian dynamics simulations we postulate that in the parameter range\nmost relevant for cytoskeletal filaments there is a distinct scaling behavior\nwith f_c \\tau*=Wi^(3/4) f_c (x) with Wi=\\gamma \\tau* and the scaling variable\nx=(l_p/L)(Wi)^(-1/3); here \\tau* is the time the polymer's center of mass\nrequires to diffuse its own contour length L. Comparing these results with\nexperimental data on F-actin we find that the Wi^(3/4) scaling law agrees\nquantitatively significantly better with the data than the classical Wi^(2/3)\nlaw. Finally, we extend our results to single ring polymers in shear flow, and\nfind similar results as for linear polymers with slightly different power laws."
    },
    {
        "anchor": "A Quantum-mechanical Approach for Constrained Macromolecular Chains: Many approaches to three-dimensional constrained macromolecular chains at\nthermal equilibrium, at about room temperatures, are based upon constrained\nClassical Hamiltonian Dynamics (cCHDa). Quantum-mechanical approaches (QMa)\nhave also been treated by different researchers for decades. QMa address a\nfundamental issue (constraints versus the uncertainty principle) and are\nversatile: they also yield classical descriptions (which may not coincide with\nthose from cCHDa, although they may agree for certain relevant quantities).\nOpen issues include whether QMa have enough practical consequences which differ\nfrom and/or improve those from cCHDa. We shall treat cCHDa briefly and deal\nwith QMa, by outlining old approaches and focusing on recent ones.",
        "positive": "Odd Viscosity in Chiral Passive Suspensions: Prior studies have revealed that nonzero odd viscosity is an essential\nproperty for chiral active fluids. Here we report that such an odd viscosity\nalso exists in suspensions of non-active or non-externally-driven but\nchirally-shaped particles. Computational simulations are carried out for\nmonolayers of dense ratchets in simple shear and planar extensional flows. The\ncontact between two ratchets can be either frictionless or\ninfinitely-frictional, depending on their teeth and sliding directions at the\ncontact point. Our results show that the ratchet suspension has the\nintermediate shear/extensional viscosity as compared with the suspensions of\nsmooth and gear-like particles. Meanwhile, the ratchet suspensions show nonzero\neven and odd components of the first normal stress coefficient, which indicates\nthe mixed feature of conventional complex fluids and chiral viscous fluids."
    },
    {
        "anchor": "The dynamics of filament assembly define cytoskeletal network morphology: The actin cytoskeleton is a key component in the machinery of eukaryotic\ncells, and it selfassembles out of equilibrium into a wide variety of\nbiologically crucial structures. While the molecular mechanisms involved are\nwell characterized, the physical principles governing the spatial arrangement\nof actin filaments are not understood. Here we propose that the dynamics of\nactin network assembly from growing filaments results from a competition\nbetween diffusion, bundling, and steric hindrance, and is responsible for the\nrange of observed morphologies. Our model and simulations thus predict an\nabrupt dynamical transition between homogeneous and strongly bundled networks\nas a function of the actin polymerization rate. This suggests that cells may\neffect dramatic changes to their internal architecture through minute\nmodifications of their nonequilibrium dynamics. Our results are consistent with\navailable experimental data.",
        "positive": "Squeezing out the last 1 nanometer of water: A detailed nanomechanical\n  study: In this study, we present a detailed analysis of the squeeze-out dynamics of\nnanoconfined water confined between two hydrophilic surfaces measured by\nsmall-amplitude dynamic atomic force microscopy (AFM). Explicitly considering\nthe instantaneous tip-surface separation during squeezeout, we confirm the\nexistence of an adsorbed molecular water layer on mica and at least two\nhydration layers. We also confirm the previous observation of a sharp\ntransition in the viscoelastic response of the nanoconfined water as the\ncompression rate is increased beyond a critical value (previously determined to\nbe about 0.8 nm/s). We find that below the critical value, the tip passes\nsmoothly through the molecular layers of the film, while above the critical\nspeed, the tip encounters \"pinning\" at separations where the film is able to\ntemporarily order. Pre-ordering of the film is accompanied by increased force\nfluctuations, which lead to increased damping preceding a peak in the film\nstiffness once ordering is completed. We analyze the data using both\nKelvin-Voigt and Maxwell viscoelastic models. This provides a complementary\npicture of the viscoelastic response of the confined water film."
    },
    {
        "anchor": "Hydrodynamic boundary effects on thermophoresis of confined colloids: We study hydrodynamic slowing-down of a particle moving in a temperature\ngradient perpendicular to a wall. At distances much smaller than the particle\nradius, $h\\ll a$, lubrication approximation leads to the reduced velocity\n$u/u_{0}=3\\frac{h}{a}\\ln \\frac{a}{h}$, with respect to the bulk value $u_{0}$.\nWith Brenner's result for confined diffusion, we find that the trapping\nefficiency, or effective Soret coefficient, increases logarithmically as the\nparticle gets very close to the wall. This provides a quantitative explanation\nfor the recently observed enhancement of thermophoretic trapping at short\ndistances. Our discussion of parallel and perpendicular thermophoresis in a\ncapillary, reveals a very a good agreement with five recent experiments on\ncharged polystyrene particles.",
        "positive": "Effect of contact location on the crushing strength of aggregates: This work deals with the effect of the contact location distribution on the\ncrushing of granular materials. At first, a simple drop weight experiment was\ndesigned in order to study the effect of the location of three contact edges on\nthe fracture pattern and the strength of a model cylindrical particle. The\nsample was placed on two bottom contact edges symmetrically distributed with\nreference to the vertical symmetry plane of the particle and subjected to an\nimpact at the top. Angle $\\alpha$ between the plane connecting a bottom contact\nedge to the centerline of the cylinder and a vertical plane was varied. The\nenergy required to fracture the particle was shown to be an increasing function\nof angle $\\alpha$. Peculiar crack patterns were also observed. Then, we present\na discrete model of grain fracture based on the work of Neveu et al. (2016) and\nemploy it for a numerical analysis of the problem. The cylindrical particle is\ndiscretized by means of a space filling Vorono\\\"i tessellation, and submitted\nto a compression test for different values of angle $\\alpha$. In agreement with\nexperiments, simulations predict a strong effect of the contact orientation on\nthe strength of the particle as well as similar fracture patterns. The effect\nof the number of contacts is also explored and the importance of a potential\npre-load is emphasized. We show that the fracture pattern: (i) is diametrical\nin case of diametrically opposed edges, (ii) has an inverted Y-shape in the\ncase of three or four edges. Interestingly, in the latter case, if one of the\nlateral edges is slightly shifted, the fracture initiates and even propagates\ndiametrically. Furthermore, the particle strength increases with the number of\ncontacts."
    },
    {
        "anchor": "Density-polarity coupling in confined active polar films: asters,\n  spirals, and biphasic orientational phases: Topological defects in active polar fluids can organise spontaneous flows and\ninfluence macroscopic density patterns. Both of them play, for example, an\nimportant role during animal development. Yet the influence of density on\nactive flows is poorly understood. Motivated by experiments on cell monolayers\nconfined to discs, we study the coupling between density and polar order for a\ncompressible active polar fluid in presence of a +1 topological defect. As in\nthe experiments, we find a density-controlled spiral-to-aster transition. In\naddition, biphasic orientational phases emerge as a generic outcome of such\ncoupling. Our results highlight the importance of density gradients as a\npotential mechanism for controlling flow and orientational patterns in\nbiological systems.",
        "positive": "Dynamic dielectric response of electrorheological fluids in drag flow: We have determined the response time of dilute electrorheological fluids (ER)\nin drag flow from the dynamic dielectric response. On the basis of a kinetic\nrate equation a new formula was derived to approximate the experimental\ntime-dependent dielectric permittivity during the temporal evolution of the\nmicrostructure. The dielectric response time was compared to the standard\nrheological response time extracted from the time-dependent shear stress, and a\ngood agreement was obtained. We found that the dielectric method is more\nsensitive to detect any transient during the chain formation process. The\nexperimental saturation value of the dielectric permittivity corresponding to\nthe equilibrium microstructure was estimated on the basis of formulas derived\nfrom the Clausius-Mossotti equation."
    },
    {
        "anchor": "A novel modulated phase of liquid crystals: Covariant elasticity in the\n  context of soft, achiral smectic-C materials: Ginzburg-Landau-de Gennes -type covariant theories are extensively used in\nconnection with twist grain boundary (TGB) phases of chiral smectogens. We\nanalyze the stability conditions for the linear, covariant elasticity theory of\nsmectic-C liquid crystals in the context of achiral materials, and predict an\nequilibrium modulated structure with an oblique wavevector. We suggest that a\nprevious experimental observation of stripes in smectic-C is consistent with\nthe predicted structure.",
        "positive": "Topological Defects and Interactions in Nematic Emulsions: Inverse nematic emulsions in which surfactant-coated water droplets are\ndispersed in a nematic host fluid have distinctive properties that set them\napart from dispersions of two isotropic fluids or of nematic droplets in an\nisotropic fluid. We present a comprehensive theoretical study of the\ndistortions produced in the nematic host by the dispersed droplets and of\nsolvent mediated dipolar interactions between droplets that lead to their\nexperimentally observed chaining. A single droplet in a nematic host acts like\na macroscopic hedgehog defect. Global boundary conditions force the nucleation\nof compensating topological defects in the nematic host. Using variational\ntechniques, we show that in the lowest energy configuration, a single water\ndroplet draws a single hedgehog out of the nematic host to form a tightly bound\ndipole. Configurations in which the water droplet is encircled by a\ndisclination ring have higher energy. The droplet-dipole induces distortions in\nthe nematic host that lead to an effective dipole-dipole interaction between\ndroplets and hence to chaining."
    },
    {
        "anchor": "Re-entrant Melting in Polydisperse Hard Spheres: The effect of polydispersity on the freezing transition of hard spheres is\nexamined within a moment description. At low polydispersities a single\nfluid-to-crystal transition is recovered. With increasing polydispersity we\nfind a density above which the crystal melts back into an amorphous phase. The\nrange of densities over which the crystalline phase is stable shrinks with\nincreasing polydispersity until, at a certain level of polydispersity, the\ncrystal disappears completely from the equilibrium phase diagram. The two\ntransitions converge to a single point which we identify as the polydisperse\nanalogue of a point of equal concentration. At this point, the freezing\ntransition is continuous in a thermodynamic sense.",
        "positive": "Modeling deswelling, thermodynamics, structure, and dynamics in ionic\n  microgel suspensions: Ionic microgel particles in a good solvent swell to an equilibrium size\ndetermined by a balance of electrostatic and elastic forces. When crowded,\nionic microgels deswell owing to a redistribution of microions inside and\noutside the particles. The concentration-dependent deswelling affects the\ninteractions between the microgels, and consequently the suspension properties.\nWe present a comprehensive theoretical study of crowding effects on\nthermodynamic, structural, and dynamic properties of weakly cross-linked ionic\nmicrogels in a good solvent. The microgels are modeled as microion- and\nsolvent-permeable colloidal spheres with fixed charge uniformly distributed\nover the polymer gel backbone, whose elastic and solvent-interaction free\nenergies are described using Flory-Rehner theory. Two mean-field methods for\ncalculating the crowding-dependent microgel radius are investigated, and\ncombined with calculations of the net microgel charge characterizing the\nelectrostatic part of an effective microgel pair potential, with charge\nrenormalization accounted for. Using this effective pair potential,\nthermodynamic and static suspension properties are calculated including the\nosmotic pressure and microgel pair distribution function. The latter is used in\nour calculations of dynamic suspension properties, where we account for\nhydrodynamic interactions. Results for diffusion and rheological properties are\npresented over ranges of microgel concentration and charge. We show that\ndeswelling mildly enhances self- and collective diffusion and the osmotic\npressure, lowers the suspension viscosity, and significantly shifts the\nsuspension crystallization point to higher concentrations. The paper presents a\nbottom-up approach to efficiently computing suspension properties of crowded\nionic microgels using single-particle characteristics."
    },
    {
        "anchor": "Two step melting of the Weeks-Chandler-Anderson system in two dimensions: We present a detailed numerical simulation study of a two dimensional system\nof particles interacting via the Weeks-Chandler-Anderson potential, the\nrepulsive part of the Lennard-Jones potential. With reduction of density, the\nsystem shows a two-step melting: a continuous melting from solid to hexatic\nphase, followed by a a first order melting of hexatic to liquid. The\nsolid-hexatic melting is consistent with the\nKosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) scenario and shows\ndislocation unbinding. The first order melting of hexatic to fluid phase, on\nthe other hand, is dominated by formation of string of defects at the\nhexatic-fluid interfaces.",
        "positive": "Glassy dynamics in relaxation of soft-mode turbulence: The autocorrelation function of pattern fluctuation is used to study\nsoft-mode turbulence (SMT), a spatiotemporal chaos observed in homeotropic\nnematics. We show that relaxation near the electroconvection threshold deviates\nfrom the exponential. To describe this relaxation, we propose a compressed\nexponential appearing in dynamics of glass forming liquids. Our findings\nsuggest that coherent motion contributes to SMT dynamics. We also confirmed\nthat characteristic time is inversely proportional to electroconvection's\ncontrol parameter."
    },
    {
        "anchor": "Correct Use of the Lifshitz-Slyosov-Wagner Expression for the\n  Calculation of the Average Radius of an Oil-In-Water (o/w) Emulsion Subject\n  to Coalescence: The analytic expression proposed by Lifshitz-Slyozov and Wagner (LSW theory)\nfor the linear variation of the cube average radius (R3) of an emulsion as\nfunction of time (t) is commonly used to appraise the effect of Ostwald\nripening. However, we proved here both experimentally and theoretically that\nsuch approach is incorrect in those cases in which the coalescence of the drops\ncannot be prevented. In this event, the expression of LSW should be corrected\nin order to account for the actual average radius of the emulsion at each time,\nand instead of the radius predicted by the equations of LSW without\nconsideration of the coalescence process.",
        "positive": "Roles of packing fraction, microscopic friction and projectile spin in\n  cratering by impact: From small seeds falling from trees to asteroids colliding with planets and\nmoons, the impact of projectiles onto granular targets occurs in nature at\ndifferent scales. In this paper, we investigate open questions in the mechanics\nof granular cratering, in particular the forces acting on the projectile, and\nthe roles of granular packing, grain-grain friction and projectile spin. For\nthat, we carried out DEM (discrete element method) computations of the impact\nof solid projectiles on a cohesionless granular medium, where we varied the\nprojectile and grain properties (diameter, density, friction and packing\nfraction) for different available energies (within relatively small values). We\nfound that a denser region forms below the projectile, pushing it back and\ncausing its rebound by the end of its motion, and that solid friction affects\nconsiderably the crater morphology. Besides, we show that the penetration\nlength increases with the initial spin of the projectile, and that differences\nin initial packing fractions can engender the diversity of scaling laws found\nin the literature. Finally, we propose an ad hoc scaling that collapsed our\ndata for the penetration length and can perhaps unify existing correlations.\nOur results provide new insights into the formation of craters in granular\nmatter."
    },
    {
        "anchor": "Many-Chain Effects on the Co-nonsolvency of Polymer Brushes in a Good\n  Solvent Mixture: Polymer brushes normally swell in a good solvent and collapse in a poor\nsolvent. An abnormal response of polymer brushes, so-called co-nonsolvency, is\nthe phenomenon where the brush counter-intuitively collapses in a good solvent\nmixture. In this work, we employed molecular dynamics simulations to\ninvestigate the structural properties of the grafted polymers on the occurrence\nof co-nonsolvency. Brushes with various grafting densities were considered to\nstudy the effect of topological excluded volumes on the co-nonsolvency. We\nfound that the brush height follows a novel scaling behavior of the grafting\ndensity $h \\sim \\sigma_{\\text g}^{0.71}$ in the co-nonsolvent mixture. Using\nthe scaling exponent and Alexander-de Gennes theory, an analytic function that\npredicts the monomer density was obtained. The many-chain effects in the\nco-nonsolvent lead to the formation of both intermolecular and intramolecular\nbridging structures. Increasing the grafting density entails lower looping\nevents occuring because of the intermolcular bridging, causing diverse\nstructural properties. We report how the average thickness, the polymer\norientation, and the looping probability varies as the grafting density\nincreases. Based on these observations, we constructed a phase diagram of the\npolymer brush system using the average thickness and orientation as order\nparameters. Our simulations and analytical results reveal the nature of\nco-nonsolvency in polymer brushes in an explicit way and will help to provide\npractical guidelines for applications such as drug delivery and sensor devices.",
        "positive": "Atomic-phase interference devices based on ring-shaped Bose-Einstein\n  condensates: Two ring case: We theoretically investigate the ground-state properties and quantum dynamics\nof a pair of adjacent ring-shaped Bose-Einstein condensates that are coupled\nvia tunneling. This device, which is the analogue of a symmetric\nsuperconducting quantum interference device, is the simplest version of what we\nterm an Atomic-Phase Interference Device (APHID). The two-ring APHID is shown\nto be sensitive to rotation."
    },
    {
        "anchor": "New insights on carbon black suspension rheology -- anisotropic\n  thixotropy and anti-thixotropy: We report a detailed experimental study of peculiar thixotropic dynamics of\ncarbon black (CB, Vulcan XC-72) suspensions in mineral oil, specifically the\nobservation of sequential stress increase then decrease at a fixed shear rate\nin a step-down test. We verify that such dynamics, though peculiar, come from a\ntrue material response rather than experimental artifacts. We also reveal how\nthis long-time stress decay is associated with anti-thixotropy, rather than\nviscoelasticity, by using orthogonal superposition (OSP) rheometry to probe\nviscoelastic moduli during the step-down tests. The orthogonal storage and loss\nmodulus are present, showing this two-timescale recovery then decay response,\nwhich demonstrates that this response is anti-thixotropic, and it involves\nshear-induced structuring. We further show a mechanical anisotropy in the CB\nsuspension under shear using OSP. Based on the rheological results, a\nmicrostructural schematic is proposed, considering qualitatively thixotropic\nstructure build-up, anti-thixotropic densification, and anisotropic structure\nevolution. Our observation for these CB suspensions is outside the standard\nparadigm of thixotropic structure-parameter models, and the elastic response\nprovides us with new insight into the transient dynamics of CB suspensions.",
        "positive": "Simple models for two-dimensional tunable colloidal crystals in rotating\n  ac electric fields: We compare the behavior of a new two-dimensional aqueous colloidal model\nsystem with a simple numerical treatment. To the first order the attractive\ninteraction between the colloids induced by an in-plane rotating ac electric\nfield is dipolar, while the charge stabilization leads to a shorter ranged,\nYukawa-like repulsion. In the crystal-like 'rafts' formed at sufficient field\nstrengths, we find quantitative agreement between experiment and Monte Carlo\nsimulation, except in the case of strongly interacting systems, where the well\ndepth of the effective potential exceeds 250 times the thermal energy. The\n'lattice constant' of the crystal-like raft is located approximately at the\nminimum of the effective potential, resulting from the sum of the Yukawa and\ndipolar interactions.The experimental system has display applications, owing to\nthe possibility of tuning the lattice spacing with the external electric field.\nLimitations in the applied field strength and relative range of the\nelectrostatic interactions of the particles result in a reduction in tunable\nlattice spacing for small and large particles, respectively. The optimal\nparticle size for maximizing the lattice spacing tunability was found to be\naround 1000 nm."
    },
    {
        "anchor": "Force-dependent bond dissociation explains the rate-dependent fracture\n  of vitrimers: We investigate the rate-dependent fracture of vitrimers by conducting a tear\ntest. Based on the relationship between the frac-ture energy and the thickness\nof vitrimer films, we, for the first time, obtain the intrinsic fracture energy\nand bulk dissipation of vitrimers during crack extension. The intrinsic\nfracture energy strongly depends on tear speed, and such dependence can be well\nexplained by Eyring theory. In contrast, the bulk dissipation only weakly\ndepends on tear speed, which is drastically different from observations on\ntraditional viscoelastic polymers. We ascribe such a weak rate-dependence to\nthe strong force-sensitivity of the exchange reaction of the dynamic covalent\nbond in the vitrimer.",
        "positive": "Orientational dynamics in supercooled glycerol computed from MD\n  simulations: self and cross contributions: The orientational dynamics of supercooled glycerol using molecular dynamics\nsimulations for temperatures ranging from 323 K to 253 K, is probed through\ncorrelation functions of first and second ranks of Legendre polynomials,\npertaining respectively to dielectric spectroscopy (DS) and depolarized dynamic\nlight scattering (DDLS). The self, cross, and total correlation functions are\ncompared with relevant experimental data. The computations reveal the low\nsensitivity of DDLS to cross-correlations, in agreement with what is found in\nexperimental work, and strengthen the idea of directly comparing DS and DDLS\ndata to evaluate the effect of cross-correlations in polar liquids. The\nanalysis of the net static cross-correlations and their spatial decomposition\nshows that, although cross-correlations extend over nanometric distances, their\nnet magnitude originates, in the case of glycerol, from the first shell of\nneighbouring molecules. Accessing the angular dependence of the static\ncorrelation allows us to get a microscopic understanding of why the rank-1\ncorrelation function is more sensitive to cross-correlation than its rank-2\ncounterpart."
    },
    {
        "anchor": "Viscosity independent diffusion mediated by death and reproduction in\n  biofilms: Bacterial biofilms, surface-attached communities of cells, are in some\nrespects similar to colloidal solids; both are densely packed with non-zero\nyield stresses. However, unlike non-living materials, bacteria reproduce and\ndie, breaking mechanical equilibrium and inducing collective dynamic responses.\nWe report experiments and theory investigating the motion of immotile Vibrio\ncholerae, which can kill each other and reproduce in biofilms. We vary\nviscosity by using bacterial variants that secrete different amounts of\nextracellular matrix polymers, but are otherwise identical. Unlike\nthermally-driven diffusion, in which diffusivity decreases with increased\nviscosity, we find that cellular motion mediated by death and reproduction is\nindependent of viscosity over timescales relevant to bacterial reproduction. To\nunderstand this surprising result, we use two separate modeling approaches.\nFirst we perform explicitly mechanical simulations of one-dimensional chains of\nVoigt-Kelvin elements that can die and reproduce. Next, we perform an\nindependent statistical approach, modeling Brownian motion with the classic\nLangevin equation under an effective temperature that depends on cellular\ndivision rate. The diffusion of cells in both approaches agrees quite well,\nsupporting a kinetic interpretation for the effective temperature used here and\ndeveloped in previous work. As the viscoelastic behavior of biofilms is\nbelieved to play a large role in their anomalous biological properties, such as\nantibiotic resistance, the independence of cellular diffusive motion ---\nimportant for biofilm growth and remodeling --- on viscoelastic properties\nlikely holds ecological, medical, and industrial relevance.",
        "positive": "Reciprocal Space Mapping for Dummies: Grazing Incidence X-ray Diffraction (GIXD) is a surface sensitive X-ray\ninvestigation technique (or geometry configuration) that can reveal the\nstructural properties of a film deposited on a flat substrate. The term grazing\nindicates that the angle between the incident beam and the film is small\n(typically below 0.5 degrees). This essential technique has been employed on\nliquid crystals, nanoparticles and colloids, nanostructures, corrosion\nprocesses, polymers, bio-materials, interfaces, materials for solar cells,\nphotodiodes, and transistors, etc. Diffraction patterns in GIXD geometry are\ntypically captured with a 2D detector, which outputs images in pixel\ncoordinates. A step required to perform analyses such as grain size estimation,\ndisorder, preferred orientation, quantitative phase analysis of the probed film\nsurface, etc., consists in converting the diffraction image from pixel\ncoordinates to the momentum transfer or scattering vector in sample coordinates\n(the reciprocal space mapping). This momentum transfer embeds information on\nthe crystal or polycrystal and its intrinsic rotation with respect to the\nsubstrate. In this work we derive, in a rigorous way, the reciprocal space\nmapping equations for a 3D+1S diffractometer in a way that is understandable to\nanyone with basic notions of linear algebra, geometry, and X-ray diffraction."
    },
    {
        "anchor": "Lattice model of protein conformations: We introduce a lattice model of protein conformations which is able to\nreproduce second structures of proteins (alpha--helices and beta--sheets). This\nmodel is based on the following two main ideas. First, we model backbone parts\nof amino acid residues in a peptide chain by edges in the cubic lattice which\nare not parallel to the coordinate axes. Second, we describe possible contacts\nof amino acid residues using a discrete model of the Ramachandran plot.\n  This model allows to describe hydrogen bonds between the residues in the\nbackbone of the peptide chain. In particular the lattice secondary structures\nhave the correct structure of hydrogen bonds. We also take into account the\nside chains of amino acid residues and their interaction.\n  The expression for the energy of conformation of a lattice protein which\ncontains contributions from hydrogen bonds in the backbone of the peptide chain\nand from interaction of the side chains is proposed. The lattice secondary\nstructures are local minima of the introduced energy.",
        "positive": "Simulational study of anomalous tracer diffusion in hydrogels: In this article, we analyze different factors that affect the diffusion\nbehavior of small tracer particles (as they are used e.g.in fluorescence\ncorrelation spectroscopy (FCS)) in the polymer network of a hydrogel and\nperform simulations of various simplified models. We observe, that under\ncertain circumstances the attraction of a tracer particle to the polymer\nnetwork strands might cause subdiffusive behavior on intermediate time scales.\nIn theory, this behavior could be employed to examine the network structure and\nswelling behavior of weakly crosslinked hydrogels with the help of FCS."
    },
    {
        "anchor": "Nonlinear dielectric response of Debye, alpha, and beta relaxation in\n  1-propanol: We present nonlinear dielectric measurements of glass-forming 1-propanol, a\nprototypical example for the monohydroxy alcohols that are known to exhibit\nunusual relaxation dynamics, namely an additional Debye relaxation, slower than\nthe structural alpha relaxation. Applying high ac fields of 468 kV/cm allows\nfor a detailed investigation of the nonlinear properties of all three\nrelaxation processes occurring in 1-propanol, namely the Debye, alpha, and beta\nrelaxation. Both the field-induced variations of dielectric constant and loss\nare reported. Polarization saturation and the absorption of field energy govern\nthe findings in the Debye-relaxation regime, well consistent with the suggested\ncluster-like nature of the relaxing entities. The behavior of the alpha\nrelaxation is in good accord with the expectations for a heterogeneous\nrelaxation scenario. Finally, the Johari-Goldstein beta-relaxation in\n1-propanol seems to exhibit no or only weak field dependence, in agreement with\nrecent findings for the excess wing of canonical glass formers.",
        "positive": "Virial coefficients and vapor-liquid equilibria of the EXP6 and 2-Yukawa\n  fluids: Virial coefficients $B_2$ through $B_4$ and the vapor-liquid equilibria for\nthe EXP6 and 2-Yukawa (2Y) fluids have been determined using numerical\nintegrations and Gibbs ensemble simulations, respectively. The chosen 2Y models\nhave been recently determined as an appropriate reference fluid for the\nconsidered EXP6 models."
    },
    {
        "anchor": "Tethered Semiflexible Polymer under Large Amplitude Oscillatory Shear: The properties of a semiflexible polymer with fixed ends exposed to\noscillatory shear flow are investigated by simulations. The two-dimensionally\nconfined polymer is modeled as a linear bead-spring chain, and the interaction\nwith the fluid is described by the Brownian multiparticle collision dynamics\napproach. For small shear rates, the tethering of the ends leads to a\nmore-or-less linear oscillatory response. However, at high shear rates, we\nfound a strongly nonlinear reaction, with a polymer (partially) wrapped around\nthe fixation points. This leads to an overall shrinkage of the polymer.\nDynamically, the location probability of the polymer center-of-mass position is\nlargest on a spatial curve resembling a lima\\c{c}on, although with an\ninhomogeneous distribution. We found shear-induced modifications of the\nnormal-mode correlation functions, with a frequency doubling at high shear\nrates. Interestingly, an even-odd asymmetry for the Cartesian components of the\ncorrelation functions appears, with rather similar spectra for odd $x$- and\neven $y$-modes and vice versa. Overall, our simulations yielded an intriguing\nnonlinear behavior of tethered semiflexible polymers under oscillatory shear\nflow.",
        "positive": "Connecting particle clustering and rheology in attractive particle\n  networks: The structural properties of suspensions and other multiphase systems are\nvital to overall processability, functionality and acceptance among consumers.\nTherefore, it is crucial to understand the intrinsic connection between the\nmicrostructure of a material and the resulting rheological properties. Here, we\ndemonstrate how the transitions in the microstructural conformations can be\nquantified and correlated to rheological measurements. We find semi-local\nparameters from graph theory, the mathematical study of networks, to be useful\nin linking structure and rheology. Our results, using capillary suspensions as\na model system, show that the use of the clustering coefficient, in combination\nwith the coordination number, is able to capture not only the agglomeration of\nparticles, but also measures the formation of groups. These phenomena are\ntightly connected to the rheological properties. The present sparse networks\ncannot be described by established techniques such as betweenness centrality."
    },
    {
        "anchor": "Zero-gravity thermal convection in granular gases: Previous experimental and theoretical evidence has shown that convective flow\nmay appear in granular fluids if subjected to a thermal gradient and gravity\n(Rayleigh-B\\'enard-type convection). In contrast to this, we present here\nevidence of gravity-free thermal convection in a granular gas, with no presence\nof external thermal gradients either. Convection is here maintained steady by\ninternal gradients due to dissipation and thermal sources at the same\ntemperature. The granular gas is composed by identical disks and is enclosed in\na rectangular region. Our results are obtained by means of an event-driven\nalgorithm for inelastic hard disks.",
        "positive": "Geometry of surface mediated interactions: Soft interfaces can mediate interactions between particles bound to them. The\nforce transmitted through the surface geometry on a particle may be expressed\nas a closed line integral of the surface stress tensor around that particle.\nThis contour may be deformed to exploit the symmetries present; for two\nidentical particles, one obtains an exact expression for the force between them\nin terms of the local surface geometry of their mid-plane; in the case of a\nfluid membrane the sign of the interaction is often evident. The approach, by\nconstruction, is adapted directly to the surface and is independent of its\nparameterization. Furthermore, it is applicable for arbitrarily large\ndeformations; in particular, it remains valid beyond the linear small-gradient\nregime."
    },
    {
        "anchor": "Diffusion limited cluster aggregation with irreversible flexible bonds: Irreversible diffusion limited cluster aggregation (DLCA) of hard spheres was\nsimulated using Brownian cluster dynamics. Bound spheres were allowed to move\nfreely within a specified range, but no bond breaking was allowed. The\nstructure and size distribution of the clusters was investigated before\ngelation. The pair correlation function and the static structure factor of the\ngels were determined as a function of the volume fraction and time. Bond\nflexibility led to local densification of the clusters and the gels, with a\ncertain degree of order. At low volume fractions densification of the clusters\noccurred during their growth, but at higher volume fractions it occurred mainly\nafter gelation. At very low volume fractions, the large scale structure\n(fractal dimension), size distribution and growth kinetics of the clusters was\nfound to be close to that known for DLCA with rigid bonds. Restructuring of the\ngels continued for long times, indicating that aging processes in systems with\nstrong attraction do not necessarily involve bond breaking. The mean square\ndisplacement of particles in the gels was determined. It is shown to be highly\nheterogeneous and to increase with decreasing volume fraction.",
        "positive": "Theory of microphase separation in bidisperse chiral membranes: We present a Ginzburg-Landau theory of micro phase separation in a bidisperse\nchiral membrane consisting of rods of opposite handendness. This model system\nundergoes a phase transition from an equilibrium state where the two components\nare completely phase separated to a microphase separated state composed of\ndomains of a finite size comparable to the twist penetration depth.\nCharacterizing the phenomenology using linear stability analysis and numerical\nstudies, we trace the origin of the discontinuous change in domain size that\noccurs during this to a competition between the cost of creating an interface\nand the gain in twist energy for small domains in which the twist penetrates\ndeep into the center of the domain."
    },
    {
        "anchor": "Which wavenumbers determine the thermodynamic stability of soft matter\n  quasicrystals?: For soft matter to form quasicrystals an important ingredient is to have two\ncharacteristic lengthscales in the interparticle interactions. To be more\nprecise, for stable quasicrystals, periodic modulations of the local density\ndistribution with two particular wavenumbers should be favored, and the ratio\nof these wavenumbers should be close to certain special values. So, for simple\nmodels, the answer to the title question is that only these two ingredients are\nneeded. However, for more realistic models, where in principle all wavenumbers\ncan be involved, other wavenumbers are also important, specifically those of\nthe second and higher reciprocal lattice vectors. We identify features in the\nparticle pair interaction potentials which can suppress or encourage density\nmodes with wavenumbers associated with one of the regular crystalline orderings\nthat compete with quasicrystals, enabling either the enhancement or suppression\nof quasicrystals in a generic class of systems.",
        "positive": "Existence of an omni-directional photonic band gap in one-dimensional\n  periodic dielectric structures: It is shown that total reflection for all incident angles does not require a\ntwo- or three-dimensional photonic crystal. We demonstrate that a\none-dimensional photonic crystal can exhibit total omni-directional reflection\nfor any incident wave within some frequency region. The formation of the\nomni-directional gap is discussed and a wide range of realistic fabrication\nparameters is proposed."
    },
    {
        "anchor": "Anomalous Scaling for Hydrodynamic Lubrication of Conformal Surfaces: The hydrodynamic regime of the Stribeck curve giving the friction coefficient\n$\\mu$ as a function of the dimensionless relative sliding speed (the Sommerfeld\nnumber, $S$) of two contacting non-conformal surfaces is usually considered\ntrivial, with $\\mu \\sim S$. We predict that for conformal surfaces contacting\nover large areas, a combination of independent length scales gives rise to a\nuniversal power-law with a non-trivial exponent, $\\mu\\sim S^{2/3}$, for a thick\nlubrication film. Deviations as the film thins (decreasing $S$) may\nsuperficially resemble the onset of elastohydrodynamic lubrication, but are due\nto a crossover between hydrodynamic regimes. Our experiments as well as recent\nmeasurements of chocolate lubrication confirm these predictions.",
        "positive": "The compression of a heavy floating elastic film: We study the effect of film density on the uniaxial compression of thin\nelastic films at a liquid--fluid interface. Using a combination of experiments\nand theory, we show that dense films first wrinkle and then fold as the\ncompression is increased, similarly to what has been reported when the film\ndensity is neglected. However, we highlight the changes in the shape of the\nfold induced by the film's own weight and extend the model of Diamant and\nWitten [Phys.Rev.Lett. 2011, 107, 164302, arXiv:1107.5505] to understand these\nchanges. In particular, we suggest that it is the weight of the film that\nbreaks the up-down symmetry apparent from previous models, but elusive\nexperimentally. We then compress the film beyond the point of self-contact and\nobserve a new behaviour dependent on the film density: the single fold that\nforms after wrinkling transitions into a closed loop after self-contact,\nencapsulating a cylindrical droplet of the upper fluid. The encapsulated drop\neither causes the loop to bend upward or to sink deeper as compression is\nincreased, depending on the relative buoyancy of the drop-film combination. We\npropose a model to qualitatively explain this behaviour. Finally, we discuss\nthe relevance of the different buckling modes predicted in previous theoretical\nstudies and highlight the important role of surface tension in the shape of the\nfold that is observed from the side -- an aspect that is usually neglected in\ntheoretical analyses."
    },
    {
        "anchor": "Local stress and elastic properties of lipid membranes obtained from\n  elastic energy variation: A theory and computational method are provided for the calculation of lipid\nmembranes elastic parameters, which overcomes the difficulties of the existing\napproaches and can be applied not only to single-component but also to\nmulti-component membranes. It is shown that the major elastic parameters can be\ndetermined as the derivatives of the stress-profile moments with respect to\nstretching. The more general assumption of the global incompressibility,\ninstead of the local one, is employed, which allows the measurement of the\nlocal Poisson's ratio from the response of the stress profile to the isotropic\nambient pressure. In the case of the local incompressibility and quadratic\nenergy law, a direct relation between the bending modulus and Gaussian\ncurvature modulus is established.",
        "positive": "Active particles crossing sharp viscosity gradients: Active particles (living or synthetic) often move through inhomogeneous\nenvironments, such as gradients in light, heat or nutrient concentration, that\ncan lead to directed motion (or taxis). Recent research has explored\ninhomogeneity in the rheological properties of a suspending fluid, in\nparticular viscosity, as a mechanical (rather than biological) mechanism for\ntaxis. Theoretical and experimental studies have shown that gradients in\nviscosity can lead to reorientation due to asymmetric viscous forces. In\nparticular, recent experiments with Chlamydomonas reinhardtii algae swimming\nacross sharp viscosity gradients have observed that the microorganisms are\nredirected and scattered due to the viscosity change. Here we develop a simple\ntheoretical model to explain these experiments. We model the swimmers as\nspherical squirmers and focus on small, but sharp, viscosity changes. We derive\na law, analogous to Snell's law of refraction, that governs the orientation of\nactive particles in the presence of a viscosity interface. Theoretical\npredictions show good agreement with experiments and provide a mechanistic\nunderstanding of the observed reorientation process."
    },
    {
        "anchor": "Hydrodynamic interactions in active colloidal crystal microrheology: In dense colloids it is commonly assumed that hydrodynamic interactions do\nnot play a role. However, a found theoretical quantification is often missing.\nWe present computer simulations that are motivated by experiments where a large\ncolloidal particle is dragged through a colloidal crystal. To qualify the\ninfluence of long-ranged hydrodynamics, we model the setup by conventional\nLangevin dynamics simulations and by an improved scheme with limited\nhydrodynamic interactions. This scheme significantly improves our results and\nallows to show that hydrodynamics strongly impacts on the development of\ndefects, the crystal regeneration as well as on the jamming behavior.",
        "positive": "On the effect of heterogeneity in stochastic interacting-particle\n  systems: We study stochastic particle systems made up of heterogeneous units. We\nintroduce a general framework suitable to analytically study this kind of\nsystems and apply it to two particular models of interest in economy and\nepidemiology. We show that particle heterogeneity can enhance or decrease the\ncollective fluctuations depending on the system, and that it is possible to\ninfer the degree and the form of the heterogeneity distribution in the system\nby measuring only global variables and their fluctuations."
    },
    {
        "anchor": "Ground State of a System of N Hard Core Quantum Particles in 1D Box: The ground state of a system of $N$ impenetrable hard core quantum particles\nin a 1-D box is analyzed by using a new scheme applied recently to study a\nsimilar system of two such particles {\\it [Centl. Eur. J. Phys., 2(4), 709\n(2004)]}. Accordingly, each particle of the system behaves like an independent\nentity represented by a {\\it macro-orbital}, -a kind of pair waveform identical\nto that of a pair of particles moving with ($q$, $-q$) momenta at their {\\it\ncenter of mass} which may have any momentum $K$ in the laboratory frame. It\nconcludes: (i) $<A\\delta{(x)}> = 0$, (ii) $<x> \\ge \\lambda/2$ and (iii) $q \\ge\nq_o (= \\pi/d)$ (with $d = L/N$ being the average nearest neighbour distance),\n{\\it etc.} While all bosons in their ground state have $q = q_o$ and $K = 0$,\nfermions have $q= q_o$ with different $K$ ranging between 0 and $K = K_F$ (the\nFermi wave vector). Independent of their bosonic or fermionic nature, all\nparticles in the ground state define a close packed arrangement of their equal\nsize wave packets representing an ordered state in phase ($\\phi-$)space with\n$\\Delta\\phi = 2n\\pi$ (with $n$ = 1,2,3, ...), $<x> = \\lambda/2 = d$, and $q =\nq_o$. As such our approach uses greatly simplified mathematical formulation and\nrenders a visibly clear picture of the low energy states of the systems and its\nresults supplement earlier studies in providing their complete understanding.",
        "positive": "Shear viscosity scaling of granular suspensions across dilute to dense\n  regimes: In this letter, following an extensive experimental validation, we perform\nconstant-volume shearing simulations of non-Brownian granular suspensions using\nthe discrete element method coupled with the lattice Boltzmann method. We\nchoose a wide range of solid fractions, shear rates, fluid viscosities,\nparticle sizes, and inter-particle frictional coefficients to obtain a scaling\nsolution for the viscous behavior of suspensions in both dilute and dense\nregimes. This letter demonstrates that, with a proposed dilute-dense\ntransitional solid fraction, $\\phi_d$, there exists a strong correlation\nbetween the inverse relative viscosity and the shear stress. This work\nincorporates both the $\\phi$-dependence and the $\\dot{\\gamma}$-dependence of\nsuspension viscosity in a universal framework, which provides a scaling\nsolution for granular suspensions across dilute and dense regimes and sheds\nlight on the dilute-dense transition mechanisms."
    },
    {
        "anchor": "Geometry for evolving topographies of light-responsive plastic sheets: Recently, topography change by illumination of pre-stretched, flat sheets\ncovered in ink of optical density varying in-plane has been demonstrated by\nMailen\\textit{ et al}, Smart Materials and Structures, 2019. They reduce an\nanalysis of the problem to one of metric change in the sheets in the thin\nlimit, that is, to a question of geometry. We present the explicit form of the\ncontraction field needed to produce the bowls these authors were interested in,\nusing a method that can also yield the contraction field for more general\ndesired, circularly-symmetric topography development. We give as examples the\nfields required for developing paraboloids and catenoids.",
        "positive": "Controlling crystallization and its absence: Proteins, colloids and\n  patchy models: The ability to control the crystallization behaviour (including its absence)\nof particles, be they biomolecules such as globular proteins, inorganic\ncolloids, nanoparticles, or metal atoms in an alloy, is of both fundamental and\ntechnological importance. Much can be learnt from the exquisite control that\nbiological systems exert over the behaviour of proteins, where protein\ncrystallization and aggregation are generally suppressed, but where in\nparticular instances complex crystalline assemblies can be formed that have a\nfunctional purpose. We also explore the insights that can be obtained from\ncomputational modelling, focussing on the subtle interplay between the\ninterparticle interactions, the preferred local order and the resulting\ncrystallization kinetics. In particular, we highlight the role played by\n``frustration'', where there is an incompatibility between the preferred local\norder and the global crystalline order, using examples from atomic glass\nformers and model anisotropic particles."
    },
    {
        "anchor": "Molecular Dynamics Simulations of Active Matter using LAMMPS: LAMMPS is a widely popular classical Molecular Dynamics package. It was\ndesigned for materials modeling but it is well prepared for simulations in Soft\nMatter. The use packages like LAMMPS has advantages and disadvantages. The main\nadvantage is the optimization of the methods, mainly for parallel computing.\nThe main disadvantage is that, due to the complexity of the code, it ha long\nlearning curve. One purpose of these notes is to shorten that curve for\nresearchers are starting to use LAMMPS to simulate soft active matter. In these\nnotes, we first discuss some Molecular Dynamics methods implemented in LAMMPS.\nWe present an hands-on introduction to first-time users and we finish with an\nadvanced hands-on section, where we implement and test Active Brownian\nparticles simulations.",
        "positive": "Close packing of rods on spherical surfaces: We study the optimal packing of short, hard spherocylinders confined to lie\ntangential to a spherical surface, using simulated annealing and molecular\ndynamics simulations. For clusters of up to twelve particles, we map out the\nchanges in the geometry of the closest-packed configuration as a function of\nthe aspect ratio $L/D$, where $L$ is the cylinder length and $D$ the diameter\nof the rods. We find a rich variety of cluster structures. For larger clusters,\nwe find that the best-packed configurations up to around 100 particles are\nhighly dependent on the exact number of particles and aspect ratio. For even\nlarger clusters, we find largely disordered clusters for very short rods ($L/D\n= 0.25$), while slightly longer rods ($L/D = 0.5$ or $1$) prefer a global\nbaseball-like geometry of smectic-like domains, similar to the behavior of\nlarge-scale nematic shells. Our results provide predictions for experimentally\nrealizable systems of colloidal rods trapped at the interface of emulsion\ndroplets."
    },
    {
        "anchor": "Periodically Aligned Liquid Crystal: Potential application for\n  projection displays: A nematic liquid crystal (NLC) layer with the anisotropy axis modulated at a\nfixed rate q in the transverse direction is considered. If the layer locally\nconstitutes a half-wave plate, then the thin-screen approximation predicts 100%\n-efficient diffraction of normal incident wave. The possibility of implementing\nsuch a layer via anchoring at both surfaces of a cell with thickness L is\nstudied as a function of parameter qL and threshold values of this parameter\nare found for a variety of cases. Distortions of the structure of director in\ncomparison with the preferable ideal profile are found via numerical modeling.\nFreedericksz transition is studied for this configuration. Coupled-mode theory\nis applied to light propagation through such cell allowing to account for\nwalk-off effects and effects of nematic distortion. In summary, this cell is\nsuggested as a means for projection display; high efficiency is predicted.",
        "positive": "Estimation of anisotropic bending rigidities and spontaneous curvatures\n  of crescent curvature-inducing proteins from tethered-vesicle experimental\n  data: The Bin/amphiphysin/Rvs (BAR) superfamily proteins have a crescent binding\ndomain and bend biomembranes along the domain axis. However, their anisotropic\nbending rigidities and spontaneous curvatures have not been experimentally\ndetermined. Here, we estimated these values from the bound protein densities on\ntethered vesicles using a mean-field theory of anisotropic bending energy and\norientation-dependent excluded volume. The dependence curves of the protein\ndensity on the membrane curvature are fitted to the experimental data for the\nI-BAR and N-BAR domains reported by C. Prevost et al. Nat. Commun. 6, 8529\n(2015) and F.-C. Tsai et al. Soft Matter 17, 4254 (2021), respectively. For the\nI-BAR domain, all three density curves of different chemical potentials exhibit\nexcellent fits with a single parameter set of anisotropic bending energy. When\nthe classical isotropic bending energy is used instead, one of the curves can\nbe fitted well, but the others exhibit large deviations. In contrast, for the\nN-BAR domain, two curves are not well-fitted simultaneously using the\nanisotropic model, although it is significantly improved compared to the\nisotropic model. This deviation likely suggests a cluster formation of the\nN-BAR domains."
    },
    {
        "anchor": "Phase diagrams of Janus fluids with up-down constrained orientations: A class of binary mixtures of Janus fluids formed by colloidal spheres with\nthe hydrophobic hemispheres constrained to point either up or down are studied\nby means of Gibbs ensemble Monte Carlo simulations and simple analytical\napproximations. These fluids can be experimentally realized by the application\nof an external static electrical field. The gas-liquid and demixing phase\ntransitions in five specific models with different patch-patch affinities are\nanalyzed. It is found that a gas-liquid transition is present in all the\nmodels, even if only one of the four possible patch-patch interactions is\nattractive. Moreover, provided the attraction between like particles is\nstronger than between unlike particles, the system demixes into two subsystems\nwith different composition at sufficiently low temperatures and high densities.",
        "positive": "Distribution Functions, Loop Formation Probabilities and Force-Extension\n  Relations in a Model for Short Double-Stranded DNA Molecules: We obtain, using transfer matrix methods, the distribution function $P(R)$ of\nthe end-to-end distance, the loop formation probability and force-extension\nrelations in a model for short double-stranded DNA molecules. Accounting for\nthe appearance of ``bubbles'', localized regions of enhanced flexibility\nassociated with the opening of a few base pairs of double-stranded DNA in\nthermal equilibrium, leads to dramatic changes in $P(R)$ and unusual\nforce-extension curves. An analytic formula for the loop formation probability\nin the presence of bubbles is proposed. For short {\\em heterogeneous} chains,\nwe demonstrate a strong dependence of loop formation probabilities on sequence,\nas seen in recent experiments."
    },
    {
        "anchor": "Fluid-bicontinuous gels stabilized by interfacial colloids: low and high\n  molecular weight fluids: Carefully tuned composite materials can have properties wholly unlike their\nseparate constituents. We review the development of one example:\ncolloid-stabilized emulsions with bicontinuous liquid domains. These\nnon-equilibrium structures resemble the sponge mesophase of surfactants;\nhowever, in the colloid-stabilized case the interface separating the liquid\ndomains is itself semi-solid. The arrangement of domains is created by\narresting liquid-liquid phase separation via spinodal decomposition. Dispersed\ncolloids exhibiting partial wettability become trapped on the newly created\ninterface and jam together as the domains coarsen. Similar structures have been\ncreated in polymer blends stabilized using either interfacial nanoparticles or\nclay platelets. Here it has been possible to create the domain arrangement\neither by phase separation or by direct mixing of the melt. The low\nmolecular-weight liquid and polymer based structures have been developed\nindependently and much can be learnt by comparing the two.",
        "positive": "Electrostatic Interactions and Electro-osmotic Properties of\n  Semipermeable Surfaces: We consider two charged semipermeable membranes, which bound bulk electrolyte\nsolutions and are separated by a thin film of salt-free liquid. Small\ncounter-ions permeate into the gap, which leads to a steric charge separation\nin the system. To quantify the problem, we define an effective surface charge\ndensity of imaginary impermeable surface, which mimics an actual semipermeable\nmembrane and greatly simplify analysis. The effective charge depends on\nseparation, generally differ from the real one, and could even be of the\nopposite sign. From the exact and asymptotic solutions of the nonlinear\nPoisson-Boltzmann equation, we obtain the distribution of the potential and of\ncounter-ions in the system. We then derive explicit formulae for the disjoining\npressure in the gap and electro-osmotic velocity, and show that both are\ncontrolled by the effective surface charge."
    },
    {
        "anchor": "Herschel-Bulkley rheology from lattice kinetic theory of soft-glassy\n  materials: We provide a clear evidence that a two species mesoscopic Lattice Boltzmann\n(LB) model with competing short-range attractive and mid-range repulsive\ninteractions supports emergent Herschel-Bulkley (HB) rheology, i.e. a power-law\ndependence of the shear-stress as a function of the strain rate, beyond a given\nyield-stress threshold. This kinetic formulation supports a seamless transition\nfrom flowing to non-flowing behaviour, through a smooth tuning of the\nparameters governing the mesoscopic interactions between the two species. The\npresent model may become a valuable computational tool for the investigation of\nthe rheology of soft-glassy materials on scales of experimental interest.",
        "positive": "Dynamical Correlation Length and Relaxation Processes in a Glass Former: We investigate the relaxation process and the dynamical heterogeneities of\nthe kinetically constrained Kob--Anderson lattice glass model, and show that\nthese are characterized by different timescales. The dynamics is well described\nwithin the diffusing defect paradigm, which suggest to relate the relaxation\nprocess to a reverse--percolation transition. This allows for a geometrical\ninterpretation of the relaxation process, and of the different timescales."
    },
    {
        "anchor": "Frank's constant in the hexatic phase: Using video-microscopy data of a two-dimensional colloidal system the\nbond-order correlation function G6 is calculated and used to determine the\ntemperature-dependence of both the orientational correlation length xi6 in the\nisotropic liquid phase and the Frank constant F_A in the hexatic phase. F_A\ntakes the value 72/pi at the hexatic to isotropic liquid phase transition and\ndiverges at the hexatic to crystal transition as predicted by the KTHNY-theory.\nThis is a quantitative test of the mechanism of breaking the orientational\nsymmetry by disclination unbinding.",
        "positive": "Continuum modelling of shear start-up in soft glassy materials: Yield stress fluids (YSFs) display a dual nature highlighted by the existence\nof a yield stress such that YSFs are solid below the yield stress, whereas they\nflow like liquids above it. Under an applied shear rate $\\dot\\gamma$, the\nsolid-to-liquid transition is associated with a complex spatiotemporal\nscenario. Still, the general phenomenology reported in the literature boils\ndown to a simple sequence that can be divided into a short-time response\ncharacterized by the so-called \"stress overshoot\", followed by stress\nrelaxation towards a steady state. Such relaxation can be either long-lasting,\nwhich usually involves the growth of a shear band that can be only transient or\nthat may persist at steady-state, or abrupt, in which case the solid-to-liquid\ntransition resembles the failure of a brittle material, involving avalanches.\nHere we use a continuum model based on a spatially-resolved fluidity approach\nto rationalize the complete scenario associated with the shear-induced yielding\nof YSFs. Our model provides a scaling for the coordinates of the stress maximum\nas a function of $\\dot\\gamma$, which shows excellent agreement with\nexperimental and numerical data extracted from the literature. Moreover, our\napproach shows that such a scaling is intimately linked to the growth dynamics\nof a fluidized boundary layer in the vicinity of the moving boundary. Yet, such\nscaling is independent of the fate of that layer, and of the long-term behavior\nof the YSF. Finally, when including the presence of \"long-range\" correlations,\nwe show that our model displays a ductile to brittle transition, i.e., the\nstress overshoot reduces into a sharp stress drop associated with avalanches,\nwhich impacts the scaling of the stress maximum with $\\dot\\gamma$. Our work\noffers a unified picture of shear-induced yielding in YSFs, whose complex\nspatiotemporal dynamics are deeply connected to non-local effects."
    },
    {
        "anchor": "A van der Waals free energy in electrolytes revisited: A system of three electrolytes separated by two parallel planes is\nconsidered. Each region is described by a dielectric constant and a Coulomb\nfluid in the Debye-H\\\"uckel regime. In their book Dispersion Forces, Mahanty\nand Ninham have given the van der Waals free energy of this system. We rederive\nthis free energy by a different method, using linear response theory and the\nelectrostatic Maxwell stress tensor for obtaining the dispersion force.",
        "positive": "Linear stability of cylindrical, multicomponent vesicles: Vesicles are important surrogate structures made up of multiple phospholipids\nand cholesterol distributed in the form of a lipid bilayer. Tubular vesicles\ncan undergo pearling i.e., formation of beads on the liquid thread akin to the\nRayleigh-Plateau instability. Previous studies have inspected the effects of\nsurface tension on the pearling instabilities of single-component vesicles. In\nthis study, we perform a linear stability analysis on a multicomponent\ncylindrical vesicle. We solve the Stokes equations along with the Cahn-Hilliard\nequations to develop the linearized dynamic equations governing the vesicle\nshape and surface concentration fields. This helps us show that multicomponent\nvesicles can undergo pearling, buckling, and wrinkling even in the absence of\nsurface tension, which is a significantly different result from studies on\nsingle-component vesicles. This behaviour arises due to the competition between\nthe free energies of phase separation, line tension, and bending for this\nmulti-phospholipid system. We determine the conditions under which axisymmetric\nand non-axisymmetric modes are dominant, and supplement our results with an\nenergy analysis that shows the sources for these instabilities. We further show\nthat these trends qualitatively match recent experiments."
    },
    {
        "anchor": "Active buckling of pressurized spherical shells : Monte Carlo Simulation: We study the buckling of pressurized spherical shells by Monte Carlo\nsimulations in which the detailed balance is explicitly broken -- thereby\ndriving the shell active, out of thermal equilibrium. Such a shell typically\nhas either higher (active) or lower (quiescent) fluctuations compared to one in\nthermal equilibrium depending on how the detailed balance is broken. We show\nthat for the same set of elastic parameters, a shell that is not buckled in\nthermal equilibrium can be buckled if turned active. Similarly, a shell that is\nbuckled in thermal equilibrium can unbuckle if turned quiescent. Based on this\nresult, we suggest that it is possible to experimentally design microscopic\nelastic shells whose buckling can be optically controlled.",
        "positive": "Inertial migration of bidisperse suspensions flowing in microchannels:\n  effect of particle diameters ratio: Up to date, inertial migration of particles in microflows has demonstrated a\ngreat potential for a wide range of applications. In particular, this\nphenomenon is used to achieve particle separation or sorting in a suspension.\nRecent works reported that the focusing mode of particles can be modified in a\npolydisperse suspension. Nevertheless, the impact of the particle sizes in a\nmixture on their inertial migration has been rarely studied up to now. Thus, we\nhave investigated in this work the influence of bidispersity on the lateral\nmigration of the particles towards equilibrium positions and on their\nlongitudinal ordering into trains. Different changes in the particles behavior\nwere observed when the ratio between the particle sizes (dp1/dp2) varied from\n1.64 to 4.58."
    },
    {
        "anchor": "Relationship between thermodynamic perturbation and scaled particle\n  theories for fused dimers fluids: Various approaches are reviewed that use scaled particle theories to describe\ndumbbell fluids made of tangent or overlapped hard spheres. Expressions\nencountered in the literature are written in a form similar to that presented\nin the thermodynamic perturbation theory introduced by Wertheim for chains and\ndeveloped in statistical associating fluid theory (SAFT). Analogies and\ndifferences observed in these two types of theoretical descriptions allow one\nto propose alternative theoretical expressions to describe dumbbell fluids with\noverlapping spheres.",
        "positive": "Non-equilibrium molecular dynamics of steady-state fluid transport\n  through a 2D membrane driven by a concentration gradient: We use a novel non-equilibrium algorithm to simulate steady-state fluid\ntransport through a two-dimensional (2D) membrane due to a concentration\ngradient by molecular dynamics (MD) for the first time. We confirm that, as\nrequired by the Onsager reciprocal relations in the linear-response regime, the\nsolution flux obtained using this algorithm agrees with the excess solute flux\nobtained from an established non-equilibrium MD algorithm for pressure-driven\nflow. In addition, we show that the concentration-gradient solution flux in\nthis regime is quantified far more efficiently by explicitly applying a\ntransmembrane concentration difference using our algorithm than by applying\nOnsager reciprocity to pressure-driven flow. The simulated fluid fluxes are\ncaptured with reasonable quantitative accuracy by our previously derived\ncontinuum theory of concentration-gradient-driven fluid transport through a 2D\nmembrane [J. Chem. Phys. 151, 044705 (2019)] for a wide range of solution and\nmembrane parameters even though the simulated pore sizes are only several times\nthe size of the fluid particles. The simulations deviate from the theory\nespecially for strong solute--membrane interactions relative to the thermal\nenergy, for which the theoretical approximations break down. Our findings will\nbe beneficial for molecular-level understanding of fluid transport driven by\nconcentration gradients through membranes made from 2D materials, which have\ndiverse applications in energy harvesting, molecular separations, and\nbiosensing."
    },
    {
        "anchor": "Topological defect-propelled swimming of nematic colloids: Non-equilibrium dynamics of topological defects can be used as a fundamental\npropulsion mechanism in microscopic active matter. Here, we demonstrate\nswimming of topological defect-propelled colloidal particles in (passive)\nnematic fluids through experiments and numerical simulations. Dynamic swim\nstrokes of the topological defects are driven by colloidal rotation in an\nexternal magnetic field, causing periodic defect rearrangement which propels\nthe particles. The swimming velocity is determined by the colloid's angular\nvelocity, sense of rotation and defect polarity. By controlling them we can\nlocomote the particles along different trajectories. We demonstrate scattering\n-- that is, the effective pair interactions -- of two of our defect-propelled\nswimmers, which we show is highly anisotropic and depends on the microscopic\nstructure of the defect stroke, including the local defect topology and\npolarity. More generally, this work aims to develop biomimetic active matter\nbased on the underlying relevance of topology.",
        "positive": "Stick-slip in a stack: how slip dissonance reveals aging: We perform physical and numerical experiments to study the stick-slip\nresponse of a stack of slabs in contact through dry frictional interfaces\ndriven in quasistatic shear. The ratio between the drive's stiffness and the\nslab's shear stiffness controls the presence or absence of slip\nsynchronization. A sufficiently high stiffness ratio leads to synchronization,\ncomprising periodic slip events in which all interfaces slip simultaneously. A\nlower stiffness ratio leads to asynchronous slips and, experimentally, to the\nstick-slip amplitude becoming broadly distributed as the number of layers in\nthe stack increases. We interpret this broadening in light of the combined\neffect of complex loading paths due to the asynchronous slips and creep.\nConsequently, the aging rate of the interfaces can be readily extracted from\nthe stick-slip cycles, and it is found to be of the same order of magnitude as\nexisting experimental results on a similar material. Finally, we discuss the\nemergence of slow slips and an increase in aging-rate variations when more\nslabs are added to the stack."
    },
    {
        "anchor": "Pattern selection in radial displacements of a confined aging\n  viscoelastic fluid: Intricate fluid displacement patterns, arising from the unstable growth of\ninterfacial perturbations, can be driven by fluid viscoelasticity and surface\ntension. A soft glassy suspension ages, $i.e.$ its mechanical moduli evolve\nwith time, due to the spontaneous formation of suspension microstructures. The\nshear and time-dependent rheology of an aging suspension can be exploited to\ngenerate a wide variety of interfacial patterns during its displacement by a\nNewtonian fluid. Using video imaging, we report a rich array of interfacial\npattern morphologies: dense viscous, dendritic, viscoelastic fracture,\nflower-shaped, jagged and stable, during the miscible and immiscible\ndisplacements of an aging colloidal clay suspension by Newtonian fluids\ninjected into a radial quasi-two-dimensional geometry at different flow rates.\nWe propose a new parameter, the areal ratio, which we define as the\nfully-developed pattern area normalized by the area of the smallest circle\nenclosing it. We show that the natural logarithms of the areal ratios uniquely\nidentify the distinct pattern morphologies, such that each pattern can be\nsegregated in a three-dimensional phase diagram spanned by the suspension aging\ntime, the displacing fluid flow rate, and interfacial tension. Besides being of\nfundamental interest, our results are useful in predicting and controlling the\ngrowth of interfaces during fluid displacements.",
        "positive": "Taming active turbulence with patterned soft interfaces: Active matter embraces systems that self-organize at different length and\ntime scales, often exhibiting turbulent flows. Here, we use a\nquasi-two-dimensional nematically ordered layer of a protein-based active gel\nto experimentally demonstrate that the geometry of active flows, which we have\ncharacterized by means of the statistical distribution of eddy sizes, can be\nreversibly modified. To this purpose, the active material is prepared in\ncontact with a thermotropic liquid crystal, whose lamellar smectic-A phase\ntiles the water/oil interface with a lattice of anisotropic domains that\nfeature circular easy-flow directions. The active flow, which arises from the\nmotion of parabolic folds within the filamentous active material, becomes\neffectively confined into circulating eddies that are in registry with the\nunderlying smectic-A domains. Based on topological arguments applied to the\ncircular confinement, together with well-known properties of the active\nmaterial, we show that the structure of the active flow is determined by a\nsingle intrinsic length scale. The role of this length scale thus reemerges\nfrom setting the decay length in the exponential eddy size distribution of the\nfree turbulent regime, to determining the minimum size of circulating eddies\nfeaturing a scale-free power law. Our results demonstrate that soft-confinement\nprovides with an invaluable tool to probe the intrinsic length and time scales\nof active materials, and pave the way for further exploration looking for\nsimilarities and differences between active and passive two-dimensional\nturbulence."
    },
    {
        "anchor": "Capillary-lubrication force exerted on a 2D particle moving towards a\n  fluid interface: A rigid object moving in a viscous fluid and in close proximity with an\nelastic wall experiences self-generated elastohydrodynamic interactions. This\nhas been the subject of an intense research activity, with a recent and growing\nattention given to the particular case of elastomeric and gel-like substrates.\nHere, we address the situation where the elastic wall is replaced by a\ncapillary surface. Specifically, we analyze the lubrication flow generated by\nthe prescribed normal motion of a rigid infinite cylinder near the deformable\ninterface separating two immiscible and incompressible viscous fluids. Using a\ncombination of analytical and numerical treatments, we compute the emergent\ncapillary-lubrication force at leading order in compliance, and characterize\nits dependencies with the interfacial tension, viscosities of the fluids, and\nlength scales of the problem. Interestingly, we identify two main\ncontributions: i) a velocity-dependent adhesion-like force ; ii) an\nacceleration-dependant inertial-like force. Our results may have implications\nfor the mobility of colloids near complex interfaces and for the motility of\nconfined microbiological entities.",
        "positive": "Solitons in one-dimensional mechanical linkage: It has been observed that certain classical chains admit topologically\nprotected zero-energy modes that are localized on the boundaries. The static\nfeatures of such localized modes are captured by linearized equations of\nmotion, but the dynamical features are governed by its nonlinearity. We study\nquasi-periodic solutions of nonlinear equations of motion of one-dimensional\nclassical chains. Such quasi-periodic solutions correspond to periodic\ntrajectories in the configuration space of the discrete systems, which allows\nus to define solitons without relying on a continuum theory. Furthermore, we\nstudy the dynamics of solitons in inhomogeneous systems by connecting two\nchains with distinct parameter sets, where transmission or reflection of\nsolitons occurs at the boundary of the two chains."
    },
    {
        "anchor": "Two Distinct Time-Scale Regimes of the Effective Temperature for an\n  Aging Colloidal Glass: Colloidal dispersions of Laponite platelets are known to age slowly from\nviscous sols to colloidal glasses. We follow this aging process by monitoring\nthe diffusion of probe particles embedded in the sample via dynamic light\nscattering. Our results show that the time-dependent diffusion of the probe\nparticles scales with their size. This implies that the fluctuation-dissipation\ntheorem can be generalized for this out-of-equilibrium system by replacing the\nbath temperature with an effective temperature. Simultaneous dynamic\nrheological measurements reveal that this effective temperature increases as a\nfunction of aging time and frequency. This suggests the existence of two\nregimes: at probed time scales longer than the characteristic relaxation time\nof the Laponite dispersion, the system thermalizes with the bath, whereas at\nshorter time scales, the system is out-of-equilibrium with an effective\ntemperature greater than the bath temperature.",
        "positive": "From splashing to bouncing: the influence of viscosity on the impact of\n  suspension droplets on a solid surface: We experimentally investigated the splashing of dense suspension droplets\nimpacting a solid surface, extending prior work to the regime where the\nviscosity of the suspending liquid becomes a significant parameter. The overall\nbehavior can be described by a combination of two trends. The first one is that\nthe splashing becomes favored when the kinetic energy of individual particles\nat the surface of a droplet overcomes the confinement produced by surface\ntension. This is expressed by a particle-based Weber number $We_p$. The second\nis that splashing is suppressed by increasing the viscosity of the solvent.\nThis is expressed by the Stokes number $St$, which influences the effective\ncoefficient of restitution of colliding particles. We developed a phase diagram\nwhere the splashing onset is delineated as a function of both $We_p$ and $St$.\nA surprising result occurs at very small Stokes number, where not only\nsplashing is suppressed but also plastic deformation of the droplet. This leads\nto a situation where droplets can bounce back after impact, an observation we\nare able to reproduce using discrete particle numerical simulations that take\ninto account viscous interaction between particles and elastic energy."
    },
    {
        "anchor": "Linear Viscoelastic Properties of the Vertex Model for Epithelial\n  Tissues: Epithelial tissues act as barriers and, therefore, must repair themselves,\nrespond to environmental changes and grow without compromising their integrity.\nConsequently, they exhibit complex viscoelastic rheological behavior where\nconstituent cells actively tune their mechanical properties to change the\noverall response of the tissue, e.g., from solid-like to fluid-like. Mesoscopic\nmechanical properties of epithelia are commonly modeled with the vertex model.\nWhile previous studies have predominantly focused on the rheological properties\nof the vertex model at long time scales, we systematically studied the full\ndynamic range by applying small oscillatory shear and bulk deformations in both\nsolid-like and fluid-like phases for regular hexagonal and disordered cell\nconfigurations. We found that the shear and bulk responses in the fluid and\nsolid phases can be described by standard spring-dashpot viscoelastic models.\nFurthermore, the solid-fluid transition can be tuned by applying\npre-deformation to the system. Our study provides insights into the mechanisms\nby which epithelia can regulate their rich rheological behavior.",
        "positive": "Liquid-gas phase behavior of polydisperse dipolar hard-sphere fluid:\n  Extended thermodynamic perturbation theory for central force associating\n  potential: The liquid-gas phase diagram for polydisperse dipolar hard-sphere fluid with\npolydispersity in the hard-sphere size and dipolar moment is calculated using\nextension of the recently proposed thermodynamic perturbation theory for\ncentral force (TPT-CF) associating potential. To establish the connection with\nthe phase behavior of ferrocolloidal dispersions it is assumed that the dipole\nmoment is proportional to the cube of the hard-sphere diameter. We present and\ndiscuss the full phase diagram, which includes cloud and shadow curves,\nbinodals and distribution functions of the coexisting daughter phases at\ndifferent degrees of the system polydispersity. In all cases studied\npolydispersity increases the region of the phase instability and shifts the\ncritical point to the higher values of the temperature and density. The larger\nsize particles always fractionate to the liquid phase and the smaller size\nparticles tend to move to the gas phase. At relatively high values of the\nsystem polydispersity three-phase coexistence is observed."
    },
    {
        "anchor": "Rheology of weakly wetted granular materials - a comparison of\n  experimental and numerical data: Shear cell simulations and experiments of weakly wetted particles (a few\nvolume percent liquid binders) are compared, with the goal to understand their\nflow rheology. Application examples are cores for metal casting by core\nshooting made of sand and liquid binding materials. The experiments are carried\nout with a Couette-like rotating viscometer. The weakly wetted granular\nmaterials are made of quartz sand and small amounts of Newtonian liquids. For\ncomparison, experiments on dry sand are also performed with a modified\nconfiguration of the viscometer. The numerical model involves spherical,\nmonodisperse particles with contact forces and a simple liquid bridge model for\nindividual capillary bridges between two particles. Different liquid content\nand properties lead to different flow rheology when measuring the shear\nstress-strain relations. In the experiments of the weakly wetted granular\nmaterial, the apparent shear viscosity $\\eta_g$ scales inversely proportional\nto the inertial number $I$, for all shear rates. On the contrary, in the dry\ncase, an intermediate scaling regime inversely quadratic in $I$ is observed for\nmoderate shear rates. In the simulations, both scaling regimes are found for\ndry and wet granular material as well.",
        "positive": "Oscillatory rheotaxis of active droplets in microchannels: Biological microswimmers are known to navigate upstream of an external flow\n(positive rheotaxis) in trajectories ranging from linear, spiral to\noscillatory. Such rheotaxis stems from the interplay between the motion and\ncomplex shapes of the microswimmers, e.g. the chirality of the rotating\nflagella, the shear flow characteristics, and the hydrodynamic interaction with\na confining surface. Here, we show that an isotropic, active droplet\nmicroswimmer exhibits a unique oscillatory rheotaxis in a microchannel despite\nits simple spherical geometry. The swimming velocity, orientation, and the\nchemical wake of the active droplet undergo periodic variations between the\nconfining walls during the oscillatory navigation. Using a hydrodynamic model\nand concepts of dynamical systems, we demonstrate that the oscillatory\nrheotaxis of the active droplet emerges primarily from the interplay between\nthe hydrodynamic interaction of the finite-sized microswimmer with all the\nmicrochannel walls, and the shear flow characteristics. Such oscillatory\nrheotactic behavior is different from the directed motion near a planar wall\nobserved previously for artificial microswimmers in shear flows. Our results\nprovide a realistic understanding of the behaviour of active particles in\nconfined microflows, as will be encountered in majority of the applications\nlike targeted drug delivery."
    },
    {
        "anchor": "Quantifying the effects of neglecting many-body interactions in\n  coarse-grained models of complex fluids: We describe a general simulation scheme for assessing the thermodynamic\nconsequences of neglecting many-body effects in coarse-grained models of\ncomplex fluids. The method exploits the fact that the asymptote of a\nsimple-to-measure structural function provides direct estimates of virial\ncoefficients. Comparing the virial coefficients of an atomistically detailed\nsystem with those of a coarse-grained version described by pair potentials,\npermits the role of many-body effects to be quantified. The approach is applied\nto two models: (i) a size-asymmetrical colloid-polymer mixture, and (ii) a\nsolution of star polymers. In the latter case, coarse-graining to an effective\nfluid described by pair potentials is found to neglect important aspects of the\ntrue behaviour.",
        "positive": "Statistical mechanics of homogeneous partly pinned fluid systems: The homogeneous partly pinned fluid systems are simple models of a fluid\nconfined in a disordered porous matrix obtained by arresting randomly chosen\nparticles in a one-component bulk fluid or one of the two components of a\nbinary mixture. In this paper, their configurational properties are\ninvestigated. It is shown that a peculiar complementarity exists between the\nmobile and immobile phases, which originates from the fact that the solid is\nprepared in presence of and in equilibrium with the adsorbed fluid. Simple\nidentities follow, which connect different types of configurational averages,\neither relative to the fluid-matrix system or to the bulk fluid from which it\nis prepared. Crucial simplifications result for the computation of important\nstructural quantities, both in computer simulations and in theoretical\napproaches. Finally, possible applications of the model in the field of\ndynamics in confinement or in strongly asymmetric mixtures are suggested."
    },
    {
        "anchor": "Emergence of collective dynamical chirality for achiral active particles: Emergence of collective dynamical chirality (CDC) at mesoscopic scales plays\na key role in many formation processes of chiral structures in nature, which\nmay also provide possible routines for people to fabricate complex chiral\narchitectures. So far, most of reported CDCs are found in systems of active\nobjects with individual structure chirality or/and dynamical chirality, and\nwhether CDC can arise from simple and achiral units is still an attractive\nmystery. Here, we report a spontaneous formation of CDC in a system of both\ndynamically and structurally achiral particles motivated by active motion of\ncells. Active moving, confinement and hydrodynamic interaction are found to be\nthe three key factors. Detailed analysis shows that the system can support\nabundant collective dynamical behaviors, including rotating droplet, rotating\nbubble, CDC oscillation, array of collective rotation, as well as interesting\ntransitions such as chirality transition, structure transition and state\nreentrance.",
        "positive": "Equilibrium and nonequilibrium thermodynamics of particle-stabilized\n  thin liquid films: Our recent quasi-two-dimensional thermodynamic description of thin-liquid\nfilms stabilized by colloidal particles is generalized to describe nonuniform\nequilibrium states of films in external potentials and nonequilibrium transport\nprocesses produced in the film by gradients of thermodynamic forces. Using a\nMonte--Carlo simulation method, we have determined equilibrium equations of\nstate for a film stabilized by a suspension of hard spheres. Employing a\nmultipolar-expansion method combined with a flow-reflection technique, we have\nalso evaluated the short-time film-viscosity coefficients and collective\nparticle mobility."
    },
    {
        "anchor": "Breakdown of deterministic lateral displacement efficiency for\n  non-dilute suspensions: a numerical study: We investigate the effect of particle volume fraction on the efficiency of\ndeterministic lateral displacement (DLD) devices. DLD is a popular passive\nsorting technique for microfluidic applications. Yet, it has been designed for\ntreating dilute suspensions, and its efficiency for denser samples is not well\nknown. We perform 3D simulations based on the immersed-boundary,\nlattice-Boltzmann and finite-element methods to model the flow of red blood\ncells (RBCs) in different DLD devices. We quantify the DLD efficiency in terms\nof appropriate \"failure\" probabilities and RBC counts in designated device\noutlets. Our main result is that the displacement mode breaks down upon an\nincrease of RBC volume fraction, while the zigzag mode remains relatively\nrobust. This suggests that the separation of larger particles (such as white\nblood cells) from a dense RBC background is simpler than separating smaller\nparticles (such as platelets) from the same background. The observed breakdown\nstems from non-deterministic particle collisions interfering with the designed\ndeterministic nature of DLD devices. Therefore, we postulate that dense\nsuspension effects generally hamper efficient particle separation in devices\nbased on deterministic principles.",
        "positive": "Anomalous zeta potential in foam films: Electrokinetic effects offer a method of choice to control flows in micro and\nnanofluidic systems. While a rather clear picture of these phenomena exists now\nfor the liquid-solid interfaces, the case of liquid-air interfaces remains\nlargely unexplored. Here we investigate at the molecular level electrokinetic\ntransport in a liquid film covered with ionic surfactants. We find that the\nzeta potential, quantifying the amplitude of electrokinetic effects, depends on\nthe surfactant coverage in an unexpected way. First, it increases upon lowering\nsurfactant coverage from saturation. Second, it does not vanish in the limit of\nlow coverage, but instead approaches a finite value. This behavior is\nrationalized by taking into account the key role of interfacial hydrodynamics,\ntogether with an ion-binding mechanism. We point out implications of these\nresults for the strongly debated measurements of zeta potential at free\ninterfaces, and for electrokinetic transport in liquid foams."
    },
    {
        "anchor": "Plug flow formation and growth in da Vinci Fluids: A new, da Vinci, fluid is described as a model for flow of dense granular\nmatter. We postulate local properties of the fluid, which are generically\ndifferent from ordinary fluids in that energy is dissipated by solid friction.\nWe present the equation of flow of such a fluid and show that it gives rise to\nformation and growth of plug flow regions, which is characteristic of flow of\ngranular matter. Simple explicit examples are presented to illustrate the\nevolution of plug flow regions.",
        "positive": "Magneto-Permeability Effect in Ferrofluid Flow through Porous Media\n  studied via Multiparticle Collision Dynamics: As more and more promising applications of magnetic nanoparticles in\ncomplicated environments are explored, their flow properties in porous media\nare of increasing interest. We here propose a hybrid approach based on the\nMultiparticle Collision Dynamics Method extended to porous media via friction\nforces and coupled with Brownian Dynamics simulations of the rotational motion\nof magnetic nanoparticles' magnetic moment. We simulate flow in planar channels\nhomogeneously filled with a porous medium and verify our implementation by\nreproducing the analytical velocity profile of the Darcy-Brinkman model in the\nnon-magnetic case. In the presence of an externally applied magnetic field, the\nnon-equilibrium magnetization and friction forces lead to field-dependent\nvelocity profiles that result in effective, field-dependent permeabilities. We\nprovide a theoretical expression for this magneto-permeability effect in\nanalogy with the magneto-viscous effect. Finally, we study the flow through\nplanar channels, where only the walls are covered with a porous medium. We find\na smooth crossover from the Poiseuille profile in the center of the channel to\nthe Brinkman-Darcy flow in the porous layers. We propose a simple estimate of\nthe thickness of the porous layer based on the flow rate and maximum flow\nvelocity."
    },
    {
        "anchor": "Invited review: Clogging of granular materials in bottlenecks: During the past decades, notable improvements have been achieved in the\nunderstanding of static and dynamic properties of granular materials, giving\nrise to appealing new concepts like jamming, force chains, non-local rheology\nor the inertial number. The `saltcellar' can be seen as a canonical example of\nthe characteristic features displayed by granular materials: an apparently\nsmooth flow is interrupted by the formation of a mesoscopic structure (arch)\nabove the outlet that causes a quick dissipation of all the kinetic energy\nwithin the system. In this manuscript, I will give an overview of this field\npaying special attention to the features of statistical distributions appearing\nin the clogging and unclogging processes. These distributions are essential to\nunderstand the problem and allow subsequent study of topics such as the\ninfluence of particle shape, the structure of the clogging arches and the\npossible existence of a critical outlet size above which the outpouring will\nnever stop. I shall finally offer some hints about general ideas that can be\nexplored in the next few years.",
        "positive": "Insights into the Structure and Ion Transport of Pectin-[BMIM][PF$_6$]\n  Electrolytes: We investigate the effect of pectin on the structure and ion transport\nproperties of the room-temperature ionic liquid electrolyte\n1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) using molecular\ndynamics simulations. We find that pectin induces intriguing structural changes\nin the electrolyte that disrupt large ionic aggregates and promote the\nformation of smaller ionic clusters, which is a promising finding for ionic\nconductivity. Due to pectin in [BMIM][PF6] electrolytes, the diffusion\ncoefficient of cations and anions is observed to decrease by a factor of four\nfor a loading of 25 wt. % of pectin in [BMIM][PF6] electrolyte. A strong\ncorrelation between the ionic diffusivities (D) and ion-pair relaxation\ntimescales ($\\tau_C$) is observed such that D~$\\tau_C^{-0.75}$ for cations and\nD~$\\tau_C^{-0.82}$ for anions. The relaxation timescale exponents indicate that\nthe ion transport mechanisms in pectin-[BMIM][PF6] electrolytes are slightly\ndistinct from those found in neat [BMIM][PF6] electrolytes (D~$\\tau_C^{-1}$).\nSince pectin marginally affects ionic diffusivities at the gain of smaller\nionic aggregates and viscosity, our results suggest that pectin-IL electrolytes\noffer improved properties for battery applications, including ionic\nconductivity, mechanical stability, and biodegradability."
    },
    {
        "anchor": "Fragmentation of shells: An analogy with the crack formation in tree\n  bark: How does a shell explode into a series of fragments upon impact? The well\naccepted explanation is Mott's theory, which considers the fragmentation of\nshells as a random process controlled by defects. However, Mott's theory is\ninadequate due to its assumption of energy conversion, and it is incapable of\nexplaining the lack of change in saturation fragment length with the increase\nin expansion velocity. In this paper, we present a theory to explain the\nphysical mechanism for fragmentation of shells and propose a highly efficient\nmodel for predicting the number of necks after fragmentation. We recognize that\nthe fragmentation problem in shells is analogous to the cracking behavior of\ntree bark, and closed form solutions is obtained to describe the relationship\nbetween the expansion velocity and the number of necks with consideration of\nthe strain rate dependent strength of the shell material. The theoretical\nresults show excellent correlation with the experimental results.",
        "positive": "Coherent X-ray Scattering Reveals Nanoscale Fluctuations in Hydrated\n  Proteins: Hydrated proteins undergo a transition in the deeply supercooled regime,\nwhich is attributed to rapid changes in hydration water and protein structural\ndynamics. Here, we investigate the nanoscale stress relaxation in hydrated\nlysozyme proteins stimulated and probed by X-ray Photon Correlation\nSpectroscopy (XPCS). This approach allows us to access the nanoscale dynamic\nresponse in the deeply supercooled regime (T = 180 K) which is typically not\naccessible through equilibrium methods. The relaxation time constants exhibit\nArrhenius temperature dependence upon cooling with a minimum in the\nKohlrausch-Williams-Watts exponent at T = 227 K. The observed minimum is\nattributed to an increase in dynamical heterogeneity, which coincides with\nenhanced fluctuations observed in the two-time correlation functions and a\nmaximum in the dynamic susceptibility quantified by the normalised variance\n$\\chi_T$. Our study provides new insights into X-ray stimulated stress\nrelaxation and the underlying mechanisms behind spatio-temporal fluctuations in\nbiological granular materials."
    },
    {
        "anchor": "Phase transitions and ordering of confined dipolar fluids: We apply a modified mean-field density functional theory to determine the\nphase behavior of Stockmayer fluids in slitlike pores formed by two walls with\nidentical substrate potentials. Based on the Carnahan-Starling equation of\nstate, a fundamental-measure theory is employed to incorporate the effects of\nshort-ranged hard sphere - like correlations while the long-ranged\ncontributions to the fluid interaction potential are treated perturbatively.\nThe liquid-vapor, ferromagnetic liquid - vapor, and ferromagnetic liquid -\nisotropic liquid first-order phase separations are investigated. The local\norientational structure of the anisotropic and inhomogeneous ferromagnetic\nliquid phase is also studied. We discuss how the phase diagrams are shifted and\ndistorted upon varying the pore width.",
        "positive": "Glassy dynamics in monodisperse hard ellipsoids: We present evidence from computer simulations for glassy dynamics in\nsuspensions of monodisperse hard ellipsoids. In equilibrium, almost spherical\nellipsoids show a first order transition from an isotropic phase to a rotator\nphase. When overcompressing the isotropic phase into the rotator regime, we\nobserve super-Arrhenius slowing down of diffusion and relaxation, accompanied\nby two-step relaxation in positional and orientational correlators. The effects\nare strong enough for asymptotic laws of mode-coupling theory to apply. Glassy\ndynamics are unusual in monodisperse systems. Typically, polydispersity in size\nor a mixture of particle species is prerequisite to prevent crystallization.\nHere, we show that a slight particle anisometry acts as a sufficient source of\ndisorder. This sheds new light on the question of which ingredients are\nrequired for glass formation."
    },
    {
        "anchor": "Influence of Pore Surface Chemistry on the Rotational Dynamics of\n  Nanoconfined Water: We have investigated the dynamics of water confined in mesostructured porous\nsilicas (SBA-15, MCM-41) and four periodic mesoporous organosilicas (PMOs) by\ndielectric relaxation spectroscopy. The influence of water-surface interaction\nhas been controlled by the carefully designed surface chemistry of PMOs that\ninvolved organic bridges connecting silica moieties with different repetition\nlengths, hydrophilicity and H-bonding capability. Relaxation processes\nattributed to the rotational motions of non-freezable water located in the\nvicinity of the pore surface were studied in the temperature range from 140 K\nto 225 K. Two distinct situations were achieved depending on the hydration\nlevel: at low relative humidity (33% RH), water formed a non-freezable layer\nadsorbed on the pore surface. At 75% RH, water formed an interfacial liquid\nlayer sandwiched between the pore surface and the ice crystallized in the pore\ncenter. In the two cases, the study revealed different water dynamics and\ndifferent dependence on the surface chemistry. We infer that these findings\nillustrate the respective importance of water-water and water-surface\ninteractions in determining the dynamics of the interfacial liquid-like water\nand the adsorbed water molecules, as well as the nature of the different\nH-bonding sites present on the pore surface.",
        "positive": "Debye-Hueckel-Bjerrum theory for charged colloids: We formulate an extension of the Debye-Hueckel-Bjerrum theory [M. E. Fisher\nand Y. Levin, Phys. Rev. Lett. 71, 3826 (1993)] to the fluid state of a highly\nasymmetric charged colloid. Allowing for the formation of clusters consisting\nof one polyion and n condensed counterions, the total Helmholtz free energy of\nthe colloidal suspension is constructed. The thermodynamic properties, such as\nthe cluster-density distribution and the pressure, are obtained by the\nminimization of the free energy under the constraints of fixed number of\npolyions and counterions. In agreement with the current experimental and Monte\nCarlo results, no evidence of any phase transition is encountered."
    },
    {
        "anchor": "Extracting Forces from Noisy Dynamics in Dusty Plasmas: Extracting environmental forces from noisy data is a common yet challenging\ntask in complex physical systems. Machine learning represents a robust approach\nto this problem, yet is mostly tested on simulated data with known parameters.\nHere we use supervised machine learning to extract the electrostatic,\nhydrodynamic, and stochastic forces acting on micron-sized charged particles\nlevitated in an argon plasma. Trained on simulated particle trajectories using\nmore than 100 dynamical and statistical features, the model predicts system\nparameters with 50\\% better accuracy than conventional methods, and provides\nnon-contact measurements of the particle charge and Debye length.",
        "positive": "Topological and geometric decomposition of nematic textures: Directional media, such as nematic liquid crystals and ferromagnets, are\ncharacterized by their topologically stabilized defects in directional order.\nIn nematics, boundary conditions and surface-treated inclusions often create\ncomplex structures, which are difficult to classify. Topological charge of\npoint defects in nematics has ambiguously defined sign and its additivity\ncannot be ensured when defects are observed separately. We demonstrate how the\ntopological charge of complex defect structures can be determined by\nidentifying and counting parts of the texture that satisfy simple geometric\nrules. We introduce a parameter called the defect rank and show that it\ncorresponds to what is intuitively perceived as a point charge based on the\nproperties of the director field. Finally, we discuss the role of free energy\nconstraints in validity of the classification with the defect rank."
    },
    {
        "anchor": "Shape Instabilities in the Dynamics of a Two-component Fluid Membrane: We study the shape dynamics of a two-component fluid membrane, using a\ndynamical triangulation monte carlo simulation and a Langevin description.\nPhase separation induces morphology changes depending on the lateral mobility\nof the lipids. When the mobility is large, the familiar labyrinthine spinodal\npattern is linearly unstable to undulation fluctuations and breaks up into\nbuds, which move towards each other and merge. For low mobilities, the membrane\nresponds elastically at short times, preferring to buckle locally, resulting in\na crinkled surface.",
        "positive": "Electrostatic co-assembly of iron oxide nanoparticles and polymers :\n  towards the generation of highly persistent superparamagnetic nanorods: A paradigm proposed recently by Boal et al. (A.K. Boal et al., Nature 404,\n746-748, 2000) deals with the possibility to use inorganic nanoparticles as\nbuilding blocks for the design and fabrication of colloidal and supracolloidal\nassemblies. It is anticipated that these constructs could be made of different\nshapes, patterns and functionalities and could constitute the components of\nfuture nanodevices including sensors, actuators or nanocircuits. Here we report\na protocol that allowed us to fabricate such nanoparticle aggregates. The\nbuilding blocks of the constructs were anionically coated iron oxide\nnanocrytals (superparamagnetic, size 7 nm) and cationic-neutral block\ncopolymers. We have shown that the electrostatic interactions between charged\nspecies can be controlled by tuning the ionic strength of the dispersion. Under\nappropriate conditions, the control of electrostatics resulted in the\nelaboration of spherical or elongated aggregates at the micrometer length\nscale. The elongated aggregates were found to be rod-like, with diameters of a\nfew hundred nanometers and lengths between 1 and 50 micrometers. In addition to\ntheir remarkable stiffness, the nanostructured rods were found to reorient\nalong with an externally applied magnetic field, in agreement with the laws of\nsuperparamagnetism."
    },
    {
        "anchor": "Vibrations and waves in soft dielectric elastomer structures: Dielectric elastomers (DEs) are a type of multifunctional materials with\nsalient features that are very attractive in developing soft, lightweight, and\nsmall-scale transducers and robotics. This paper reviews the mechanics of soft\nDE structures, focusing on their dynamic responses, including vibrations and\nwaves in typical structures. The basic formulations of nonlinear\nelectroelasticity are briefly summarized by following the descriptions of\nDorfmann and Ogden. The recent advances in the study on linearized dynamic\nproblems of DE plates and shells are then outlined according to the geometric\nconfigurations as well as the coordinates thereof adopted. Some interesting\nobservations from the numerical results are highlighted, and the underlying\nphysics is discussed. For completeness, an account of the nonlinear dynamic\ncharacteristics of DE structures is also given. For DE structures with a\nperiodic arrangement, i.e., DE phononic crystals (PCs) or metamaterials, this\npaper reviews the designs, solutions, and results to illustrate the wide-range\ntunability of band structure that is realized by large reversible deformation\nand electromechanical coupling. The present literature survey could be a useful\nguide for future studies on the dynamic topics of DE structures.",
        "positive": "Introduction to Q-tensor theory: This paper aims to provide an introduction to a basic form of the ${\\bf\nQ}$-tensor approach to modelling liquid crystals, which has seen increased\ninterest in recent years. The increase in interest in this type of modelling\napproach has been driven by investigations into the fundamental nature of\ndefects and new applications of liquid crystals such as bistable displays and\ncolloidal systems for which a description of defects and disorder is essential.\nThe work in this paper is not new research, rather it is an introductory guide\nfor anyone wishing to model a system using such a theory. A more complete\nmathematical description of this theory, including a description of flow\neffects, can be found in numerous sources but the books by Virga and Sonnet and\nVirga are recommended. More information can be obtained from the plethora of\npapers using such approaches, although a general introduction for the novice is\nlacking. The first few sections of this paper will detail the development of\nthe ${\\bf Q}$-tensor approach for nematic liquid crystalline systems and\nconstruct the free energy and governing equations for the mesoscopic dependent\nvariables. A number of device surface treatments are considered and theoretical\nboundary conditions are specified for each instance. Finally, an example of a\nreal device is demonstrated."
    },
    {
        "anchor": "On anisotropic elasticity and questions concerning its Finite Element\n  implementation: We give conditions on the strain-energy function of nonlinear anisotropic\nhyperelastic materials that ensure compatibility with the classical linear\ntheories of anisotropic elasticity. We uncover the limitations associated with\nthe volumetric deviatoric separation of the strain energy used, for example, in\nmany Finite Element (FE) codes in that it does not fully represent the behavior\nof anisotropic materials in the linear regime. This limitation has important\nconsequences. We show that, in the small deformation regime, a FE code based on\nthe volumetric-deviatoric separation assumption predicts that a sphere made of\na compressible anisotropic material deforms into another sphere under\nhydrostatic pressure loading, instead of the expected ellipsoid. For finite\ndeformations, the commonly adopted assumption that fibres cannot support\ncompression is incorrectly implemented in current FE codes and leads to the\nunphysical result that under hydrostatic tension a sphere of compressible\nanisotropic material deforms into a larger sphere.",
        "positive": "Effect of Energy Polydispersity on the Nature of Lennard-Jones Liquids: In the companion paper [T. S. Ingebrigtsen and H. Tanaka, J. Phys. Chem. B\n119, 11052 (2015)] the effect of size polydispersity on the nature of\nLennard-Jones (LJ) liquids, which represent most molecular liquids without\nhydrogen bonds, was studied. More specifically, it was shown that even highly\nsize polydisperse LJ liquids are Roskilde-simple (RS) liquids. RS liquids are\nliquids with strong correlation between constant volume equilibrium\nfluctuations of virial and potential energy and are simpler than other types of\nliquids. Moreover, it was shown that size polydisperse LJ liquids have\nisomorphs to a good approximation. Isomorphs are curves in the phase diagram of\nRS liquids along which structure, dynamics, and some thermodynamic quantities\nare invariant in dimensionless (reduced) units. In this paper, we study the\neffect of energy polydispersity on the nature of LJ liquids. We show that\nenergy polydisperse LJ liquids are RS liquids. However, a tendency of particle\nsegregation which increases with the degree of polydispersity leads to a loss\nof strong virial-potential energy correlation, but is mitigated with increasing\ntemperature and/or density. Isomorphs are a good approximation also for energy\npolydisperse LJ liquids, although particle-resolved quantities display a\nsomewhat poorer scaling compared to the mean quantities along the isomorph."
    },
    {
        "anchor": "Topological jamming of spontaneously knotted polyelectrolyte chains\n  driven through a nanopore: The advent of solid state nanodevices allows for interrogating the\nphysico-chemical properties of a polyelectrolyte chain by electrophoretically\ndriving it through a nanopore. Salient dynamical aspects of the translocation\nprocess have been recently characterized by theoretical and computational\nstudies of model polymer chains free from self-entanglement. However,\nsufficiently long equilibrated chains are necessarily knotted. The impact of\nsuch topological \"defects\" on the translocation process is largely unexplored,\nand is addressed in this study. By using Brownian dynamics simulations on a\ncoarse-grained polyelectrolyte model we show that knots, despite being trapped\nat the pore entrance, do not \"per se\" cause the translocation process to jam.\nRather, knots introduce an effective friction that increases with the applied\nforce, and practically halts the translocation above a threshold force. The\npredicted dynamical crossover, which is experimentally verifiable, is of\nrelevance in applicative contexts, such as DNA nanopore sequencing.",
        "positive": "Geometric phases and polarization patterns in multiple light scattering: Multiple light scattering is widely used to characterize dense colloidal\nsystems as well as in deep tissue imaging; experiments are often interpreted\nvia a theory of diffusion of the light intensity within a sample, neglecting\nthe vector nature of the electromagnetic wave. Recent experiments on diffuse\nbackscattering with linearly polarized light from colloidal suspensions of\nmicron size particles were found to display strong intensity variations with\nfourfold rotational symmetry when observed through an arbitrarily oriented\nlinear analyzer. We show that these polarization patterns are manifestations of\na Berry phase of the multiple scattered beam."
    },
    {
        "anchor": "Temperature Changes of Spectra of the Lattice and Surface Oscillations\n  of Organic Molecular Nano-Crystals (COMPUTER Modeling): Dependence of frequency spectra of the lattice oscillations of organic\nnano-crystals on temperature is studied at presence of vacancies in structure.\nIn a frequency spectrum a number of additional lines monotonously changing with\ntemperature is observed. Also, the spectrum of the surface oscillations is\ncalculated at temperature change. At the same time, the low-frequency line has\nnon-linear behavior with temperature change.",
        "positive": "Jamming Distance Dictates Colloidal Shear Thickening: We report experimental and computational observations of dynamic contact\nnetworks for colloidal suspensions undergoing shear thickening. The dense\nsuspensions are comprised of sterically stabilized poly(methyl methacrylate)\nhard sphere colloids that are spherically symmetric and have varied surface\nroughness. Confocal rheometry and dissipative particle dynamics simulations\nshow that the shear thickening strength scales exponentially with the scaled\ndeficit contact number and the scaled jamming distance. Rough colloids, which\nexperience additional tangential and rolling constraints, require an average of\n1.5 - 2 fewer particle contacts as compared to smooth colloids, in order to\ngenerate the same shear thickening strength. This is because the surface\nroughness enhances geometric friction in a way that the rough colloids do not\nexperience a large change in the free volume near the jamming point. In\ncontrast, smooth colloids must undergo significant reduction in the free volume\nto support an equivalent shear stress. The available free volume for different\ncolloid roughness is related to the deficiency from the maximum number of\nnearest neighbors at jamming under shear. Our results further suggest that the\nforce per contact is different for particles with different morphologies."
    },
    {
        "anchor": "Anomalous Dynamical Responses in a Driven System: The interplay between structure and dynamics in non-equilibrium steady-state\nis far from understood. We address this interplay by tracking Brownian Dynamics\ntrajectories of particles in a binary colloid of opposite charges in an\nexternal electric field, undergoing cross-over from homogeneous to lane state,\na prototype of heterogeneous structure formation in non-equilibrium systems. We\nshow that the length scale of structural correlations controls heterogeneity in\ndiffusion and consequent anomalous dynamic responses, like the exponential tail\nin probability distributions of particle displacements and stretched\nexponential structural relaxation. We generalise our observations using\nequations for steady state density which may aid to understand microscopic\nbasis of heterogeneous diffusion in condensed matter systems.",
        "positive": "Planar diagrams from optimization: We propose a new toy model of a heteropolymer chain capable of forming planar\nsecondary structures typical for RNA molecules. In this model the sequential\nintervals between neighboring monomers along a chain are considered as quenched\nrandom variables. Using the optimization procedure for a special class of\nconcave--type potentials, borrowed from optimal transport analysis, we derive\nthe local difference equation for the ground state free energy of the chain\nwith the planar (RNA--like) architecture of paired links. We consider various\ndistribution functions of intervals between neighboring monomers (truncated\nGaussian and scale--free) and demonstrate the existence of a topological\ncrossover from sequential to essentially embedded (nested) configurations of\npaired links."
    },
    {
        "anchor": "Universal scaling of shear thickening transitions: Nearly all dense suspensions undergo dramatic and abrupt thickening\ntransitions in their flow behaviour when sheared at high stresses. Such\ntransitions occur when the dominant interactions between the suspended\nparticles shift from hydrodynamic to frictional. Here, we interpret abrupt\nshear thickening as a precursor to a rigidity transition and give a complete\ntheory of the viscosity in terms of a universal crossover scaling function from\nthe frictionless jamming point to a rigidity transition associated with\nfriction, anisotropy, and shear. Strikingly, we find experimentally that for\ntwo different systems -- cornstarch in glycerol and silica spheres in glycerol\n-- the viscosity can be collapsed onto a single universal curve over a wide\nrange of stresses and volume fractions. The collapse reveals two separate\nscaling regimes, due to a crossover between frictionless isotropic jamming and\nfrictional shear jamming, with different critical exponents. The\nmaterial-specific behaviour due to the microscale particle interactions is\nincorporated into a scaling variable governing the proximity to shear jamming\nthat depends on both stress and volume fraction. This reformulation opens the\ndoor to importing the vast theoretical machinery developed to understand\nequilibrium critical phenomena to elucidate fundamental physical aspects of the\nshear thickening transition.",
        "positive": "Particle flows around an intruder: Particle flows injected as beams and scattered by an intruder are numerically\nstudied. We find a crossover of the drag force from Epstein's law to Newton's\nlaw, depending on the ratio of the speed to the thermal speed. These laws can\nbe reproduced by a simple analysis of a collision model between the intruder\nand particle flows. The crossover from Epstein's law to Stokes' law is also\nfound for the low-speed regime as the time evolution of the drag force caused\nby beam particles. We also show the existence of turbulent-like behavior of the\nparticle flows behind the intruder with the aid of the second invariant of the\nvelocity gradient tensor and the relative mean square displacement for the\nhigh-speed regime and a large intruder."
    },
    {
        "anchor": "Thermally activated vapor bubble nucleation: the Landau-Lifshitz/Van der\n  Waals approach: Vapor bubbles are formed in liquids by two mechanisms: evaporation\n(temperature above the boiling threshold) and cavitation (pressure below the\nvapor pressure). The liquid resists in these metastable (overheating and\ntensile, respectively) states for a long time since bubble nucleation is an\nactivated process that needs to surmount the free energy barrier separating the\nliquid and the vapor states. The bubble nucleation rate is difficult to assess\nand, typically, only for extremely small systems treated at atomistic level of\ndetail. In this work a powerful approach, based on a continuum diffuse\ninterface modeling of the two-phase fluid embedded with thermal fluctuations\n(Fluctuating Hydrodynamics) is exploited to study the nucleation process in\nhomogeneous conditions, evaluating the bubble nucleation rates and following\nthe long term dynamics of the metastable system, up to the bubble coalescence\nand expansion stages. In comparison with more classical approaches, this\nmethodology allows on the one hand to deal with much larger systems observed\nfor a much longer times than possible with even the most advanced atomistic\nmodels. On the other it extends contin- uum formulations to thermally activated\nprocesses, impossible to deal with in a purely determinist setting.",
        "positive": "Coefficient of restitution for wet particles: The influence of a wetting liquid on the coefficient of restitution (COR) is\ninvestigated experimentally by tracing freely falling particles bouncing on a\nwet surface. The dependence of the COR on the impact velocity and various\nproperties of the particle and the wetting liquid is presented and discussed in\nterms of dimensionless numbers that characterize the interplay between\ninertial, viscous, and surface forces. In the Reynolds number regime where the\nlubrication theory does not apply, the ratio of the film thickness to the\nparticle size is found to be a crucial parameter determining the COR."
    },
    {
        "anchor": "Non-monotonic density dependence of the diffusion of DNA fragments in\n  low-salt suspensions: The high linear charge density of 20-base-pair oligomers of DNA is shown to\nlead to a striking non-monotonic dependence of the long-time self-diffusion on\nthe concentration of the DNA in low-salt conditions. This generic non-monotonic\nbehavior results from both the strong coupling between the electrostatic and\nsolvent-mediated hydrodynamic interactions, and from the renormalization of\nthese electrostatic interactions at large separations, and specifically from\nthe dominance of the far-field hydrodynamic interactions caused by the strong\nrepulsion between the DNA fragments.",
        "positive": "Interaction and charge transfer between dielectric spheres: exact and\n  approximate analytical solutions: We present exact analytical solutions for charge transfer reactions between\ntwo arbitrarily charged hard dielectric spheres. These solutions, and the\ncorresponding exact ones for sphere-sphere interaction energies, include sums\nthat describe polarization effects to infinite orders in the inverse of the\ndistance between the sphere centers. In addition, we show that these exact\nsolutions may be approximated by much simpler analytical expressions that are\nuseful for many practical applications. This is exemplified through\ncalculations of Langevin type cross sections for forming a compound system of\ntwo colliding spheres and through calculations of electron transfer cross\nsections. We find that it is important to account for dielectric properties and\nfinite sphere sizes in such calculations, which for example may be useful for\ndescribing the evolution, growth, and dynamics of nanometer sized dielectric\nobjects such as molecular clusters or dust grains in different environments\nincluding astrophysical ones."
    },
    {
        "anchor": "Kink-antikink asymmetry and impurity interactions in topological\n  mechanical chains: We study the dynamical response of a diatomic periodic chain of rotors\ncoupled by springs, whose unit cell breaks spatial inversion symmetry. In the\ncontinuum description, we derive a nonlinear field theory which admits\ntopological kinks and antikinks as nonlinear excitations but where a\ntopological boundary term breaks the symmetry between the two and energetically\nfavors the kink configuration. Using a cobweb plot, we develop a fixed-point\nanalysis for the kink motion and demonstrate that kinks propagate without the\nPeierls-Nabarro potential energy barrier typically associated with lattice\nmodels. Using continuum elasticity theory, we trace the absence of the\nPeierls-Nabarro barrier for the kink motion to the topological boundary term\nwhich ensures that only the kink configuration, and not the antikink, costs\nzero potential energy. Further, we study the eigenmodes around the kink and\nantikink configurations using a tangent stiffness matrix approach appropriate\nfor pre-stressed structures to explicitly show how the usual energy degeneracy\nbetween the two no longer holds. We show how the kink-antikink asymmetry also\nmanifests in the way these nonlinear excitations interact with impurities\nintroduced in the chain as disorder in the spring stiffness. Finally, we\ndiscuss the effect of impurities in the (bond) spring length and build\nprototypes based on simple linkages that verify our predictions.",
        "positive": "Mean Stress Tensor of Discrete Particle Systems in Submerged Conditions: The mean stress tensor is essential to investigate the dynamics of granular\nmaterial. In this paper, we use Hamilton's principle of least action to derive\nthe averaged stress tensor of discrete granular assemblies subjected to\nhydraulic force fields, as well as rigorous conditions for a proper definition\nof the Representative Volume Element (RVE). The main goal behind our efforts is\nto upscale particle physics into a sound stress tensor for systems involving\nthe complex interaction between grains and water. We identify the contributions\nfrom the unbalanced forces, hydraulic forces, gravity, external forces, and\nparticle fluctuation to the mean stress tensor. In doing so, it is convenient\nto separate the influence of different force fields when the granular system is\nsubjected to complex environments, e.g., subaqueous conditions. The obtained\nformula is then validated by triaxial test simulations of dry and saturated\ngranular systems using the Discrete Element Method (DEM) and the\nLattice-Boltzmann Method (LBM). The results show that the deduced formula can\naccurately calculate the stress tensor of discrete assemblies with various\nbody-force fields. We used validated DEM-LBM simulations of submerged granular\ncolumn collapses to explore the physics happening at the grain scale with this\nmathematical formalism and showcase its potential. We provide a new perspective\nbased on the granular assembly scale to pursue the fluid-solid interaction. Due\nto the importance of stress analysis in the constitutive modelling of granular\nmaterials, this work could help to better obtain the stress-strain relationship\nof saturated or submerged granular systems."
    },
    {
        "anchor": "Effects of surface structure deformation on static friction at fractal\n  interfaces: The evolution of fractal surface structures with flattening of asperities was\ninvestigated using isotropically roughened aluminium surfaces loaded in\ncompression. It was found that asperity amplitude, mean roughness and fractal\ndimension decrease through increased compressive stress and number of loading\nevents. Of the samples tested, surfaces subjected to an increased number of\nloading events exhibited the most significant surface deformation and were\nobserved to exhibit higher levels of static friction at an interface with a\nsingle crystal flat quartz substrate. This suggests that the frequency of grain\nreorganisation events in geomaterials plays an important role in the\ndevelopment of intergranular friction. Fractal surfaces were numerically\nmodelled using Weierstrass- Mandelbrot based functions. From the study of\nfrictional interactions with rigid flat opposing surfaces it was apparent that\nthe effect of surface fractal dimension is more significant with increasing\ndominance of adhesive mechanisms.",
        "positive": "Numerical investigation of a particle system compared with first and\n  second gradient continua: Deformation and fracture phenomena: A discrete system constituted of particles interacting by means of a\ncentroid-based law is numerically investigated. The elements of the system move\nin the plane, and the range of the interaction can be varied from a more local\nform (first-neighbours interaction) up to a generalized nth order interaction.\nThe aim of the model is to reproduce the behaviour of deformable bodies with\nstandard (Cauchy model) or generalized (second gradient) deformation energy\ndensity. The numerical results suggest that the considered discrete system can\neffectively reproduce the behaviour of first and second gradient continua.\nMoreover, a fracture algorithm is introduced and some comparison between\nfirstand second-neighbour simulations are provided."
    },
    {
        "anchor": "Modeling of the equilibrium component of the stress tensor of filled\n  elastomeric materials with taking into account the Mullins softening effect: Elastomers are viscoelastic materials and their properties significantly\ndepend on the loading rate. The actual stress experienced by these materials is\nthe sum of equilibrium and dissipative (inelastic) terms. At very low loading\nrates we can eliminate the significant influence of time effects and model the\nmaterial as hyperelastic. In this paper, the features of the experimental\ndetermination and subsequent mathematical description of equilibrium stresses\nare considered. Verification of the proposed equations has been carried out for\na series of experiments - cyclic uniaxial tests of samples of materials on the\nbasis of the same matrix, but with different filler contents and under\ndifferent maximum degrees of deformation.",
        "positive": "Soliton-induced liquid crystal enabled electrophoresis: Manipulation of particles by a uniform electric field, known as\nelectrophoresis, is used in a wide array of applications. Of especial interest\nis electrophoresis driven by an alternating current (AC) as it eliminates\nelectrode blocking and produces a steady motion. The known mechanisms of AC\nelectrophoresis require that either the particle or the surrounding medium are\nasymmetric. This asymmetry is usually assured before the field is applied, as\nin the case of Janus spheres. We report on a new mechanism of AC\nelectrophoresis, in which the symmetry is broken only when the field exceeds\nsome threshold. The new mechanism is rooted in the nature of electrophoretic\nmedium, which is an orientationally ordered nematic liquid crystal. Below the\nthreshold, the director field of molecular orientation around a spherical\nparticle is of a quadrupolar symmetry. Above the threshold, the director forms\na polar self confined perturbation around the inclusion that oscillates with\nthe frequency of the applied field and propels the sphere. The director\nperturbations are topologically trivial and represent particle like solitary\nwaves, called \"director bullets\" or \"directrons\". The direction of\nelectrophoretic transport can be controlled by the frequency of the field. The\nAC directron induced liquid crystal enabled electrophoresis can be used to\ntransport microscopic cargo when other modes of electrophoresis such as induced\ncharge electrophoresis are forbidden."
    },
    {
        "anchor": "Gel-like granular materials with high durability and high deformability: Building materials such as concretes and mortar are formed by solidifying\ngranular slabs. Such materials are often fractured by giant forces such as\nduring earthquakes, leading to the collapse of structures and potentially\ncasualties. One avenue of enquiry to prevent cracking would be to realize a\nmaterial that can maintain a stable shape without being solidified. Here, we\nfocus on sand grains coated with silicone oil, experimentally investigating the\nYoung's modulus of a granular slab where ordinary grains and the coated grains\nare mixed in a mixing ratio $\\alpha$. It is found that the Young's modulus\nincreases rapidly at $\\alpha \\ge 0.6$. We use numerical simulation to show that\nthis sudden increase in the Young's modulus is caused by a rigidity percolation\ntransition. Furthermore, we are able to show that granular slabs containing\ncoated sand have outstanding deformability without collapsing under large\nexternal stress. We believe this may lead to the development of granular\nmaterials that are rigid under usual pressures but deformable under more\nextreme conditions, such as during seismic activity.",
        "positive": "Shear band formation in amorphous materials under oscillatory shear\n  deformation: The effect of periodic shear on strain localization in disordered solids is\ninvestigated using molecular dynamics simulations. We consider a binary mixture\nof one million atoms annealed to a low temperature with different cooling rates\nand then subjected to oscillatory shear deformation with a strain amplitude\nslightly above the critical value. It is found that the yielding transition\noccurs during one cycle but the accumulation of irreversible displacements and\ninitiation of the shear band proceed over larger number of cycles for more\nslowly annealed glasses. The spatial distribution and correlation function of\nnonaffine displacements reveal that their collective dynamics changes from\nhomogeneously distributed small clusters to a system-spanning shear band. The\nanalysis of spatially averaged profiles of nonaffine displacements indicates\nthat the location of a shear band in periodically loaded glasses can be\nidentified at least several cycles before yielding. These insights are\nimportant for development of novel processing methods and prediction of the\nfatigue lifetime of metallic glasses."
    },
    {
        "anchor": "Electrostatic Disorder-Induced Interactions in Inhomogeneous Dielectrics: We investigate the effect of quenched surface charge disorder on\nelectrostatic interactions between two charged surfaces in the presence of\ndielectric inhomogeneities and added salt. We show that in the linear\nweak-coupling regime (i.e., by including mean-field and Gaussian-fluctuations\ncontributions), the image-charge effects lead to a non-zero disorder-induced\ninteraction free energy between two surfaces of equal mean charge that can be\nrepulsive or attractive depending on the dielectric mismatch across the\nbounding surfaces and the exact location of the disordered charge distribution.",
        "positive": "Detailed dynamics of discrete Gaussian semiflexible chains with\n  arbitrary stiffness along the contour: We revisit a model of semiflexible Gaussian chains proposed by Winkler\n\\textit{et al}, solve the dynamics of the discrete description of the model and\nderive exact algebraic expressions for some of the most relevant dynamical\nobservables, such as the mean-square displacement of individual monomers, the\ndynamic structure factor, the end-to-end vector relaxation and the shear stress\nrelaxation modulus. The mathematical expressions are verified by comparing them\nwith results from Brownian dynamics simulations, reporting an excellent\nagreement. Then, we generalize the model to linear polymer chains with\narbitrary stiffness. In particular, we focus on the case of a linear polymer\nwith stiffness that changes linearly from one end of the chain to the other,\nand study the same dynamical functions previously presented. We discuss\ndifferent approaches to check whether a polymer has constant or heterogeneous\nstiffness along its contour. Overall, this work presents a new insight for a\nwell known model for semiflexible chains and provides tools that can be\nexploited to compare the predictions of the model with simulations of coarse\ngrained semiflexible polymers."
    },
    {
        "anchor": "On the Microscopic Origin of Cholesteric Pitch: We present a microscopic analysis of the instability of the nematic phase to\nchirality when molecular chirality is introduced perturbatively. We show that\npreviously neglected short-range biaxial correlations play a crucial role in\ndetermining the cholesteric pitch. We propose an order parameter which\nquantifies the chirality of a molecule.",
        "positive": "Couette Flow of Two-Dimensional Foams: We experimentally investigate flow of quasi two-dimensional disordered foams\nin Couette geometries, both for foams squeezed below a top plate and for freely\nfloating foams. With the top-plate, the flows are strongly localized and rate\ndependent. For the freely floating foams the flow profiles become essentially\nrate-independent, the local and global rheology do not match, and in particular\nthe foam flows in regions where the stress is below the global yield stress. We\nattribute this to nonlocal effects and show that the \"fluidity\" model recently\nintroduced by Goyon {\\em et al.} ({\\em Nature}, {\\bf 454} (2008)) captures the\nessential features of flow both with and without a top plate."
    },
    {
        "anchor": "Model of metameric locomotion in active directional filaments: Locomotion in segmented animals, such as annelids and myriapods (centipedes\nand millipedes), is generated by a coordinated movement known as metameric\nlocomotion, which can be also implemented in robots designed to perform\nspecific tasks. We introduce a theoretical model, based on an active\ndirectional motion of the head segment and a passive trailing of the rest of\nthe body segments, in order to formalize and study the metameric locomotion.\nThe model is specifically formulated as a steered Ornstein-Uhlenbeck curvature\nprocess, preserving the continuity of the curvature along the whole body\nfilament, and thus supersedes the simple active Brownian model, which would be\ninapplicable in this case. We obtain the probability density by analytically\nsolving the Fokker-Planck equation pertinent to the model. We also calculate\nexplicitly the correlators, such as the mean-square orientational fluctuations,\nthe orientational correlation function and the mean-square separation between\nthe head and tail segments, both analytically either via the Fokker-Planck\nequation or directly by either solving analytically or implementing it\nnumerically from the Langevin equations. The analytical and numerical results\ncoincide. Our theoretical model can help understand the locomotion of metameric\nanimals and instruct the design of metameric robots.",
        "positive": "Optimizing Packing Fraction in Granular Media Composed of Overlapping\n  Spheres: What particle shape will generate the highest packing fraction when randomly\npoured into a container? In order to explore and navigate the enormous search\nspace efficiently, we pair molecular dynamics simulations with artificial\nevolution. Arbitrary particle shape is represented by a set of overlapping\nspheres of varying diameter, enabling us to approximate smooth surfaces with a\nresolution proportional to the number of spheres included. We discover a family\nof planar triangular particles, whose packing fraction of $\\phi \\sim$ 0.73\noutpaces almost all reported experimental results for random packings of\nfrictionless particles. We investigate how $\\phi$ depends on the arrangement of\nspheres comprising an individual particle and on the smoothness of the surface.\nWe validate the simulations with experiments using 3D-printed copies of the\nsimplest member of the family, a planar particle consisting of three\noverlapping spheres with identical radius. Direct experimental comparison with\n3D-printed aspherical ellipsoids demonstrates that the triangular particles\npack exceedingly well not only in the limit of large system size but also when\nconfined to small containers."
    },
    {
        "anchor": "Defect Spirograph: Dynamical Behavior of Defects in Spatially Patterned\n  Active Nematics: Topological defects in active liquid crystals can be confined by introducing\ngradients of activity. Here, we examine the dynamical behavior of two defects\nconfined by a sharp gradient of activity that separates an active circular\nregion and a surrounding passive nematic material. Continuum simulations are\nused to explain how the interplay among energy injection into the system,\nhydrodynamic interactions, and frictional forces governs the dynamics of\ntopologically required self-propelling $+1/2$ defects. Our findings are\nrationalized in terms of a phase diagram for the dynamical response of defects\nin terms of activity and frictional damping strength. Different regions of the\nunderlying phase diagram correspond to distinct dynamical modes, namely\nimmobile defects (ID), steady rotation of defects (SR), bouncing defects (TB),\nbouncing-cruising defects (BC), dancing defects (DA), and multiple defects with\nirregular dynamics (MD). These dynamic states raise the prospect of generating\nsynchronized defect arrays for microfluidic applications.",
        "positive": "Optical far-infrared properties of graphene monolayer and multilayers: We analyze the features of the graphene mono- and multilayer reflectance in\nthe far-infrared region as a function of frequency, temperature, and carrier\ndensity taking the intraband conductance and the interband electron absorbtion\ninto account. The dispersion of plasmon mode of the multilayers is calculated\nusing Maxwell's equations with the influence of retardation included. At low\ntemperatures and high electron densities, the reflectance of multilayers as a\nfunction of frequency has the sharp downfall and the subsequent deep well due\nto the threshold of electron interband absorbtion."
    },
    {
        "anchor": "Growth regimes in three-dimensional phase separation of liquid-vapor\n  systems: The liquid-vapor phase separation is investigated via lattice Boltzmann\nsimulations in three dimensions. After expressing length and time scales in\nreduced physical units, we combined data from several large simulations (on\n$512^3$ nodes), with different values of viscosity, surface tension and\ntemperature, to obtain a single curve of rescaled length $\\hat{l}$ as a\nfunction of rescaled time $\\hat{t}$. We find evidence of the existence of\nkinetic and inertial regimes with growth exponents $\\alpha_d=1/2$ and\n$\\alpha_i=2/3$ over several time decades, with a crossover from $\\alpha_d$ to\n$\\alpha_i$ at $\\hat{t} \\simeq 1$. This allows us to rule out the existence of a\nviscous regime with $\\alpha_v=1$ in three-dimensional liquid-vapor isothermal\nphase separation, differently from what happens in binary fluid mixtures. An\nin-depth analysis of the kinetics of the phase separation process, as well as a\ncharacterization of the morphology and the flow properties, are further\npresented in order to provide clues into the dynamics of the phase-separation\nprocess.",
        "positive": "Coarse-grained conformational surface hopping: Methodology and\n  transferability: Coarse-grained (CG) conformational surface hopping (SH) adapts the concept of\nmultisurface dynamics, initially developed to describe electronic transitions\nin chemical reactions, to accurately describe classical molecular dynamics at a\nreduced level. The SH scheme couples distinct conformational basins (states),\neach described by its own force field (surface), resulting in a significant\nimprovement of the approximation to the many-body potential of mean force\n[Phys. Rev. Lett. 121, 256002 (2018)]. The present study first describes CG SH\nin more detail, through both a toy model and a three-bead model of hexane. We\nfurther extend the methodology to non-bonded interactions and report its impact\non liquid properties. Finally, we investigate the transferability of the\nsurfaces to distinct systems and thermodynamic state points, through a simple\ntuning of the state probabilities. In particular, applications to variations in\ntemperature and chemical composition show good agreement with reference\natomistic calculations, introducing a promising \"weak-transferability regime,\"\nwhere CG force fields can be shared across thermodynamic and chemical\nneighborhoods."
    },
    {
        "anchor": "Rheology and structure of a suspension of deformable particles in plane\n  Poiseuille flow: We present an experimental study of the rheology and structure of a confined\nsuspension of deformable particles flowing in a quasi-two-dimensional\nPoiseuille flow. Thanks to a precise microfluidic viscosimetry technique\ncombined with measurements of concentration profiles, our study provides the\nfirst experimental confirmation {with three-dimensional particles} of a strong\nrelationship between structuring effects and rheology, previously only reported\nin numerical simulations of purely two-dimensional systems. In conditions where\nstrong structuring effects take place due to confinement, the evolution of the\neffective viscosity with particle concentration (here, red blood cells) shows a\nremarkable succession of ranges of rapid growth and plateaus that are\nassociated to qualitative transitions in the structure of the suspension.",
        "positive": "Phase separation of mixtures after a second quench: composition\n  heterogeneities: We investigate binary mixtures undergoing phase separation after a second\n(deeper) temperature quench into two- and three-phase coexistence regions. The\nanalysis is based on a lattice theory previously developed for gas-liquid\nseparation in generic mixtures. Our previous results, which considered an\narbitrary number of species and a single quench, showed that, due to slow\nchanges in composition, dense colloidal mixtures can phase-separate in two\nstages. Moreover, the denser phase contains long-lived composition\nheterogeneities that originate as the interfaces of shrunk domains. Here we\npredict several new effects that arise after a second quench, mostly associated\nwith the extent to which crowding can slow down 'fractionation', i.e.\nequilibration of compositions. They include long-lived regular arrangements of\nsecondary domains; wetting of fractionated interfaces by oppositely\nfractionated layers; 'surface'-directed spinodal 'waves' propagating from\nprimary interfaces; a 'dead zone' where no phase separation occurs; and, in the\ncase of three-phase coexistence, filamentous morphologies arising out of\nsecondary domains."
    },
    {
        "anchor": "Theory for the rheology of dense non-Brownian suspensions: divergence of\n  viscosities and $\u03bc$-$J$ rheology: A systematic microscopic theory for the rheology of dense non-Brownian\nsuspensions characterized by the volume fraction $\\varphi$ is developed. The\ntheory successfully derives the critical behavior in the vicinity of the\njamming point (volume fraction $\\varphi_{J}$), for both the pressure $P$ and\nthe shear stress $\\sigma_{xy}$, i.e. $P \\sim \\sigma_{xy} \\sim \\dot\\gamma \\eta_0\n\\delta\\varphi^{-2}$, where $\\dot\\gamma$ is the shear rate, $\\eta_0$ is the\nshear viscosity of the solvent, and $\\delta\\varphi = \\varphi_J - \\varphi > 0$\nis the distance from the jamming point. It also successfully describes the\nbehavior of the stress ratio $\\mu = \\sigma_{xy}/P$ with respect to the viscous\nnumber $J=\\dot\\gamma\\eta_{0}/P$.",
        "positive": "Local Nonlinear Elastic Response of Extracellular Matrices: Nonlinear stiffening is a ubiquitous property of major types of biopolymers\nthat make up the extracellular matrices (ECM) including collagen, fibrin and\nbasement membrane. Within the ECM, many types of cells such as fibroblasts and\ncancer cells are known to mechanically stretch their surroundings that locally\nstiffens the matrix. Although the bulk nonlinear elastic behaviors of these\nbiopolymer networks are well studied, their local mechanical responses remain\npoorly characterized. Here, to understand how a living cell feels the nonlinear\nmechanical resistance from the ECM, we mimic the cell-applied local force using\noptical tweezers; we report that the local stiffening responses in highly\nnonlinear ECM are significantly weaker than responses found in bulk rheology,\nacross two orders of magnitude of the locally applied force since the onset of\nstiffening. With a minimal model, we show that a local point force application\ncan induce a stiffened region in the matrix, which expands with increasing\nmagnitude of the point force. Furthermore, we show that this stiffened region\nbehaves as an effective probe upon local loading. The local nonlinear elastic\nresponse can be attributed to the nonlinear growth of this effective probe that\nlinearly deforms an increasing portion of the matrix."
    },
    {
        "anchor": "Motions in a Bose condensate: X. New results on stability of\n  axisymmetric solitary waves of the Gross-Pitaevskii equation: The stability of the axisymmetric solitary waves of the Gross-Pitaevskii (GP)\nequation is investigated. The Implicitly Restarted Arnoldi Method for banded\nmatrices with shift-invert was used to solve the linearised spectral stability\nproblem. The rarefaction solitary waves on the upper branch of the\nJones-Roberts dispersion curve are shown to be unstable to axisymmetric\ninfinitesimal perturbations, whereas the solitary waves on the lower branch and\nall two-dimensional solitary waves are linearly stable. The growth rates of the\ninstabilities on the upper branch are so small that an arbitrarily specified\ninitial perturbation of a rarefaction wave at first usually evolves towards the\nupper branch as it acoustically radiates away its excess energy. This is\ndemonstrated through numerical integrations of the GP equation starting from an\ninitial state consisting of an unstable rarefaction wave and random\nnon-axisymmetric noise. The resulting solution evolves towards, and remains for\na significant time in the vicinity of, an unperturbed unstable rarefaction\nwave. It is shown however that, ultimately (or for an initial state extremely\nclose to the upper branch), the solution evolves onto the lower branch or is\ncompletely dissipated as sound.",
        "positive": "Effects of Buckling on Stress and Strain in Thin Randomly Disordered\n  Tension-Loaded Sheets: We study how crack buckling affects stress and strain in a thin sheet with\nrandom disorder. The sheet is modeled as an elastic lattice of beams where each\nof the beams have individual thresholds for breaking. A statistical\ndistribution with an exponential tail towards either weak or strong beams is\nused to generate the thresholds and the magnitude of the disorder can be varied\narbitrarily between zero and infinity. Applying a uniaxial force couple along\nthe top and bottom rows of the lattice, fracture proceeds according to where\nthe ratio of the stress field to the local strength is most intense. Since\nbreakdown is initiated from an intact sheet where the first crack appears at\nrandom, the onset and mode of buckling varies according to where and how the\ncracks grow. For a wide range of disorders the stress-strain relationships for\nbuckling sheets are compared with those for non-buckling sheets. The ratio of\nthe buckling to the non-buckling value of the maximum external force the system\ncan tolerate before breaking is found to decrease with increasing disorder, as\nis the ratio for the corresponding displacement."
    },
    {
        "anchor": "Direct observation of percolation in the yielding transition of\n  colloidal glasses: When strained beyond the linear regime, soft colloidal glasses yield to\nsteady-state plastic flow in a way that is similar to the deformation of\nconventional amorphous solids. Due to the much larger size of the colloidal\nparticles with respect to the atoms comprising an amorphous solid, colloidal\nglasses allow to obtain microscopic insight into the nature of the yielding\ntransition, as we illustrate here combining experiments, atomistic simulations,\nand mesoscopic modeling. Our results unanimously show growing clusters of\nnon-affine deformation percolating at yielding. In agreement with percolation\ntheory, the spanning cluster is fractal with a fractal dimension d_f~2, and the\ncorrelation length diverges upon approaching the critical yield strain. These\nresults indicate that percolation of highly non-affine particles is the\nhallmark of the yielding transition in disordered glassy systems.",
        "positive": "Conformational transitions of heteropolymers in dilute solutions: In this paper we extend the Gaussian self-consistent method to permit study\nof the equilibrium and kinetics of conformational transitions for\nheteropolymers with any given primary sequence. The kinetic equations earlier\nderived by us are transformed to a form containing only the mean squared\ndistances between pairs of monomers. These equations are further expressed in\nterms of instantaneous gradients of the variational free energy. The method\nallowed us to study exhaustively the stability and conformational structure of\nsome periodic and random aperiodic sequences. A typical phase diagram of a\nfairly long amphiphilic heteropolymer chain is found to contain phases of the\nextended coil, the homogeneous globule, the micro-phase separated globule, and\na large number of frustrated states, which result in conformational phases of\nthe random coil and the frozen globule. We have also found that for a certain\nclass of sequences the frustrated phases are suppressed. The kinetics of\nfolding from the extended coil to the globule proceeds through non-equilibrium\nstates possessing locally compacted, but partially misfolded and frustrated,\nstructure. This results in a rather complicated multistep kinetic process\ntypical of glassy systems."
    },
    {
        "anchor": "Localization of positive charge in DNA induced by its interaction with\n  environment: Microscopic mechanisms of positive charge transfer in DNA remain unclear. A\nquantum state of electron hole in DNA is determined by the competition of the\npi-stacking interaction $b$ sharing a charge between different base pairs and\nthe interaction $\\lambda$ with the local environment which attempts to trap\ncharge. To determine which interaction dominates we investigated charge quantum\nstates in various $(GC)_{n}$ sequences choosing DNA parameters satisfying\nexperimental data for the balance of charge transfer rates $G^{+}\n\\leftrightarrow G_{n}^{+}$, $n=2,3$ \\cite{FredMain}. We show that experimental\ndata can be consistent with theory only assuming $b\\ll \\lambda$ meaning that\ncharge is typically localized within the single $G$ site. Consequently any DNA\nsequence including the one consisting of identical base pairs behaves more like\nan insulating material then a molecular conductor. Our theory can be verified\nexperimentally, for instance measuring balance of charge transfer reactions\n$G^{+} \\leftrightarrow G_{n}^{+}$, $n \\geq 4$ and comparing the experimental\nresults with our predictions.",
        "positive": "Cooperative transitions involving hydrophobic polyelectrolytes: Hydrophobic polyelectrolytes (HPE) can solubilize bilayer membranes, form\nmicelles or can reversibly aggregate as a function of pH. The transitions are\noften remarkably sharp. We show that these cooperative transitions occur by a\ncompetition between two or more conformational states and can be explained\nwithin the framework of Monod - Wymann - Changeux (MWC) theory that was\noriginally formulated for allosteric interactions. Here we focus on the\npH-dependent destabilization and permeation of bilayer membranes by HPE. We\nformulate the general conditions that lead to sharp conformational transitions\ninvolving simple macromolecules mediated by concentration variations of\nmolecular ligands. That opens up potential applications ranging from medicine\nto the development of switchable materials."
    },
    {
        "anchor": "The buckling and invagination process during consolidation of colloidal\n  droplets: Drying a droplet of colloidal dispersion can result in complex pattern\nformation due to both development and deformation of a skin at the drop\nsurface. The present study focus on the drying process of droplets of colloidal\ndispersions in a confined geometry where direct observations of the skin\nthickness are allowed. During the drying, a buckling process is followed by a\nsingle depression growth inside the drop. The deformation of the droplet is\nfound to be generic and is studied for various colloidal dispersions. The final\nshape can be partly explained by simple energy analysis based on the\ncompetition between bending and stretching deformations. Particularly, the\nfinal shape enables us to determine precisely the critical thickness of the\nshell for buckling. This study allow us to validate theory in 2D droplets and\napply it to the case of 3D droplets where the thickness is not accessible by\ndirect observation.",
        "positive": "Macroion adsorption: The crucial role of excluded volume and coions: The adsorption of charged colloids (macroions) onto an oppositely charged\nplanar substrate is investigated theoretically. Taking properly into account\nthe finite size of the macroions, unusual behaviors are reported. It is found\nthat the role of the coions (the little salt-ions carrying the same sign of\ncharge as that of the substrate) is crucial to understand the mechanisms\ninvolved in the process of macroion adsorption. In particular, the coions can\naccumulate near the substrate's surface and lead to a counter-intuitive {\\it\nsurface charge amplification}."
    },
    {
        "anchor": "On the nature of overcharging and charge inversion in electrical double\n  layers: Understanding overcharging and charge inversion is one of the long-standing\nchallenges in soft matter and biophysics. To study these phenomena, we employ\nthe modified Gaussian renormalized fluctuation theory, which allows for the\nself-consistent accounting of spatially varying ionic strength, as well as the\nspatial variations in dielectric permittivity and excluded volume effects. The\nunderlying dependence of overcharging on the electrostatic coupling is\nelucidated by varying surface charge, counterion valency, and dielectric\ncontrast. Consistent with simulations, three characteristic regimes\ncorresponding to weak, moderate, and strong coupling are identified. Important\nfeatures like the inversion of zeta potential, crowding and ionic layering at\nthe surface are successfully captured. For weak coupling, there is no\novercharging. In the moderate coupling regime, overcharging increases with\nsurface charge. Finally, in the strong coupling regime, ionic crowding and\nsaturation in overcharging are observed. Our theory predicts non-monotonic\ndependence of charge inversion on multivalent salt concentration as well as the\naddition of monovalent salt, in quantitative agreement with experiments.",
        "positive": "Flow of granular matter in a silo with multiple exit orifices: Jamming\n  to mixing: We investigate the mixing characteristics of dry granular material while\ndraining down a silo with multiple exit orifices. The mixing in the silo, which\notherwise consists of noninteracting stagnant and flow regions, is observed to\nimprove significantly when the flow through specific orifices is stopped\nintermittently. This momentary stoppage of flow through the orifice is either\ncontrolled manually or is chosen by the system itself when the orifice width is\nsmall enough to cause spontaneous jamming and unjamming. We observe that the\noverall mixing behavior shows a systematic dependence on the frequency of\nclosing and opening of specific orifices. In particular, the silo configuration\nemploying random jamming and unjamming of any of the orifices shows early\nevidence of chaotic mixing. When operated in a multipass mode, the system\nexhibits a practical and efficient way of mixing particles."
    },
    {
        "anchor": "Jamming of Soft Particles: Geometry, Mechanics, Scaling and Isostaticity: Amorphous materials as diverse as foams, emulsions, colloidal suspensions and\ngranular media can jam into a rigid, disordered state where they withstand\nfinite shear stresses before yielding. Here we review the current understanding\nof the transition to jamming and the nature of the jammed state for disordered\npackings of particles that act through repulsive contact interactions and are\nat zero temperature and zero shear stress. We first discuss the breakdown of\naffine assumptions that underlies the rich mechanics near jamming. We then\nextensively discuss jamming of frictionless soft spheres. At the jamming point,\nthese systems are marginally stable (isostatic) in the sense of constraint\ncounting, and many geometric and mechanical properties scale with distance to\nthis jamming point. Finally we discuss current explorations of jamming of\nfrictional and non-spherical (ellipsoidal) particles. Both friction and\nasphericity tune the contact number at jamming away from the isostatic limit,\nbut in opposite directions. This allows one to disentangle distance to jamming\nand distance to isostaticity. The picture that emerges is that most quantities\nare governed by the contact number and scale with distance to isostaticity,\nwhile the contact number itself scales with distance to jamming.",
        "positive": "Low-temperature crystal structures of the hard core square shoulder\n  model: In many cases, the stability of complex structures in colloidal systems is\nenhanced by a competition between different length scales. Inspired by recent\nexperiments on nanoparticles coated with polymers, we use Monte Carlo\nsimulations to explore the types of crystal structures that can form in a\nsimple hard-core square shoulder model which explicitly incorporates two\nfavored distances between the particles. To this end, we combine Monte\nCarlo-based crystal structure finding algorithms with free energies obtained\nusing a mean-field cell theory approach, and draw phase diagrams for two\ndifferent values of the square shoulder width as a function of the density and\ntemperature. Moreover, we map out the zero-temperature phase diagram for a\nbroad range of shoulder widths. Our results show the stability of a rich\nvariety of crystal phases, such as body-centered orthogonal (BCO) lattices, not\npreviously considered for the square shoulder model."
    },
    {
        "anchor": "Electrophoretic Mobility of Polyelectrolytes within a Confining Well: We present a numerical study of polyelectrolytes electrophoresing in free\nsolution while squeezed by an axisymmetric confinement force transverse to\ntheir net displacement. Hybrid multi-particle collision dynamics and molecular\ndynamics simulations with mean-field finite Debye layers show that even though\nthe polyelectrolyte chains remain \"free-draining\", their electrophoretic\nmobility increases with confinement in nanoconfining potential wells. The\nprimary mechanism leading to the increase in mobility above the free-solution\nvalue, despite long-range hydrodynamic screening by counterion layers, is the\norientation of polymer segments within Debye layers. The observed\nlength-dependence of the electrophoretic mobility arises due to secondary\neffects of counterion condensation related to confinement compactification.",
        "positive": "Influence of Salt on the Formation and Separation of Droplet Interface\n  Bilayers: Phospholipid bilayers are a major component of the cell membrane that is in\ncontact with physiological electrolyte solutions including salt ions. The\neffect of salt on the phospholipid bilayer mechanics is an active research area\ndue to its implications for cellular function and viability. In this manuscript\nwe utilize droplet interface bilayers(DIBs), a bilayer formed artificially\nbetween two aqueous droplets, to unravel the bilayer formation and separation\nmechanics with a combination of experiments and numerical modelling under the\neffects of K$^+$, Na$^+$, Li$^+$, Ca$^{2+}$ and Mg$^{2+}$. Initially, we\nmeasured the interfacial tension and the interfacial complex viscosity of lipid\nmonolayers at a flat oil-aqueous interface and show that both properties are\nsensitive to salt concentration, ion size and valency. Subsequently, we\nmeasured DIB formation rates and show that the characteristic bilayer formation\nvelocity scales with the ratio of the interfacial tension to the interfacial\nviscosity. Next, we subjected the system to a step strain by separating the\ndrops in a stepwise manner. By tracking the evolution of the bilayer contact\nangle and radius, we show that salt influences the bilayer separation mechanics\nincluding the decay of the contact angle, the decay of the bilayer radius and\nthe corresponding relaxation time. Finally, we explain the salt effect on the\nobserved bilayer separation by means of a mathematical model comprising of the\nYoung-Laplace equation and an evolution equation."
    },
    {
        "anchor": "Equilibrium adsorption on a random site surface: We examine the reversible adsorption of spherical solutes on a random site\nsurface in which the adsorption sites are uniformly and randomly distributed on\na substrate. Each site can be occupied by one solute provided that the nearest\noccupied site is at least one diameter away. The model is characterized by the\nsite density and the bulk phase activity of the adsorbate. We develop a general\nstatistical mechanical description of the model and we obtain exact expressions\nfor the adsorption isotherms in limiting cases of large and small activity and\nsite density, particularly for the one dimensional version of the model. We\nalso propose approximate isotherms that interpolate between the exact results.\nThese theories are in good agreement with numerical simulations of the model in\ntwo dimensions.",
        "positive": "A Thermodynamic Model for Receptor Clustering: Intracellular signaling often arises from ligand-induced oligomerization of\ncell surface receptors. This oligomerization or clustering process is\nfundamentally a cooperative behavior between near-neighbor receptor molecules;\nthe properties of this cooperative process clearly affects the signal\ntransduction. Recent investigations have revealed the molecular basis of\nreceptor-receptor interactions, but a simple theoretical framework for using\nthis data to predict cluster formation has been lacking. Here, we propose a\nsimple, coarse-grained, phenomenological model for ligand-modulated receptor\ninteractions and discuss its equilibrium properties via mean-field theory. The\nexistence of a first-order transition for this model has immediate implications\nregarding the robustness of the cellular signaling response."
    },
    {
        "anchor": "Generic model for tunable colloidal aggregation in multidirectional\n  fields: Based on Brownian Dynamics computer simulations in two dimensions we\ninvestigate aggregation scenarios of colloidal particles with directional\ninteractions induced by multiple external fields. To this end we propose a\nmodel which allows continuous change in the particle interactions from\npoint-dipole-like to patchy-like (with four patches). We show that, as a result\nof this change, the non-equilibrium aggregation occurring at low densities and\ntemperatures transforms from conventional diffusion-limited cluster aggregation\n(DLCA) to slippery DLCA involving rotating bonds; this is accompanied by a\npronounced change of the underlying lattice structure of the aggregates from\nsquare-like to hexagonal ordering. Increasing the temperature we find a\ntransformation to a fluid phase, consistent with results of a simple mean-field\ndensity functional theory.",
        "positive": "Nonlinear bending theories for non Euclidean plates: Thin growing tissues (such as plant leaves) can be modelled by a bounded\ndomain $S\\subset R^2$ endowed with a Riemannian metric $g$, which models the\ninternal strains caused by the differential growth of the tissue. The elastic\nenergy is given by a nonlinear isometry-constrained bending energy functional\nwhich is a natural generalization of Kirchhoff's plate functional. We introduce\nand discuss a natural notion of (possibly non-minimising) stationarity points.\nWe show that rotationally symmetric immersions of the unit disk are stationary,\nand we give examples of metrics $g$ leading to functionals with infinitely many\nstationary points."
    },
    {
        "anchor": "Hyperuniformity of generalized random organization models: Studies of random organization models of monodisperse spherical particles\nhave shown that a hyperuniform state is achievable when the system goes through\nan absorbing phase transition to a critical state. Here we investigate to what\nextent hyperuniformity is preserved when the model is generalized to particles\nwith a size distribution and/or nonspherical shapes. We begin by examining\nbinary disks in two dimensions and demonstrate that their critical states are\nhyperuniform as two-phase media, but not hyperuniform nor multihyperuniform as\npoint patterns formed by the particle centroids. We further confirm the\ngenerality of our findings by studying particles with a continuous size\ndistribution. Finally, to study the effect of rotational degrees of freedom, we\nextend our model to noncircular particles, namely, hard rectangles with various\naspect ratios, including the hard-needle limit. Although these systems exhibit\nonly short-range orientational order, hyperuniformity is still preserved. Our\nanalysis reveals that the redistribution of the \"mass\" of the particles rather\nthan the particle centroids is central to this dynamical process. The\nconsideration of the \"active volume fraction\" of generalized random\norganization models may help to resolve which universality class they belong to\nand hence may lead to a deeper theoretical understanding of absorbing-state\nmodels. Our results suggest that general particle systems subject to random\norganization can be a robust way to fabricate a wide class of hyperuniform\nstates of matter by tuning the structures via different particle-size and\n-shape distributions. This in turn potentially enables the creation of\nmultifunctional hyperuniform materials with desirable optical, transport, and\nmechanical properties.",
        "positive": "Crystallization seeds favour crystallization only during initial growth: Crystallization represents the prime example of a disorder order transition.\nIn realistic situations, however, container walls and impurities are frequently\npresent and hence crystallization is heterogeneously seeded. Rarely the seeds\nare perfectly compatible with the thermodynamically favoured crystal structure\nand thus induce elastic distortions, which impede further crystal growth. Here\nwe use a colloidal model system, which not only allows us to quantitatively\ncontrol the induced distortions but also to visualize and follow heterogeneous\ncrystallization with single-particle resolution. We determine the sequence of\nintermediate structures by confocal microscopy and computer simulations, and\ndevelop a theoretical model that describes our findings. The crystallite first\ngrows on the seed but then, on reaching a critical size, detaches from the\nseed. The detached and relaxed crystallite continues to grow, except close to\nthe seed, which now prevents crystallization. Hence, crystallization seeds\nfacilitate crystallization only during initial growth and then act as\nimpurities."
    },
    {
        "anchor": "Force Dependence of Proteins' Transition State Position and the\n  Bell-Evans Model: Single-molecule force spectroscopy has opened a new field of research in\nmolecular biophysics and biochemistry. Pulling experiments on individual\nproteins permit us to monitor conformational transitions with high temporal\nresolution and measure their free energy landscape. The force-extension curves\nof single proteins often present large hysteresis, with unfolding forces that\nare higher than refolding ones. Therefore, the high energy of the transition\nstate (TS) in these molecules precludes kinetic rates measurements in\nequilibrium hopping experiments. In irreversible pulling experiments,\nforce-dependent kinetic rates measurements show a systematic discrepancy\nbetween the sum of the folding and unfolding TS distances derived by the\nkinetic Bell-Evans model and the full molecular extension predicted by elastic\nmodels. Here, we show that this discrepancy originates from the force-induced\nmovement of TS. Specifically, we investigate the highly kinetically stable\nprotein barnase, using pulling experiments and the Bell-Evans model to\ncharacterize the position of its kinetic barrier. Experimental results show\nthat while the TS stays at a roughly constant distance relative to the native\nstate, it shifts with force relative to the unfolded state. Interestingly, a\nconversion of the protein extension into amino acid units shows that the TS\nposition follows the Leffler-Hammond postulate: the higher the force, the lower\nthe number of unzipped amino acids relative to the native state. The results\nare compared with the quasi-reversible unfolding-folding of a short DNA\nhairpin.",
        "positive": "Effects of translational and rotational degrees of freedom on the\n  properties of model water: Molecular dynamics simulations with separate thermostats for rotational and\ntranslational motions were used to study the effects of these degrees of\nfreedom on the structure of water at a fixed density. To describe water\nmolecules, we used the SPC/E model. The results indicate that an increase of\nthe rotational temperature, $T_\\textrm{R}$, causes a significant breaking of\nthe hydrogen bonds. This is not the case, at least not to such an extent, when\nthe translational temperature, $T_\\textrm{T}$, is raised. The probability of\nfinding an empty spherical cavity (no water molecule present) of a given size,\nstrongly decreases with an increase of $T_\\textrm{R}$, but this only marginally\naffects the free energy of the hydrophobe insertion. The excess internal energy\nincreases proportionally with an increase of $T_\\textrm{R}$, while an increase\nof $T_\\textrm{T}$ yields a much smaller effect at high temperatures. The\ndiffusion coefficient of water exhibits a non-monotonous behaviour with an\nincrease of the rotational temperature."
    },
    {
        "anchor": "Stochastic Resonance of a Flexible Chain Crossing over a Barrier: We study the stochastic resonance (SR) of a flexible polymer surmounting a\nbistable-potential barrier. Due to the flexibility that can enhance crossing\nrate and change chain conformations at the barrier, the SR behaviors manifest\nmany features of an entropic SR of a new kind, such as the power amplification\npeaks at optimal chain lengths and elastic constants as well as the optimal\nnoise strengths. The pronounced peaks that emerge depending on the chain\nlengths and conformation states suggest novel means of manipulating\nbiopolymers, such as efficient separation methods, within undulating channels.",
        "positive": "Fluctuating shells under pressure: Thermal fluctuations strongly modify the large length-scale elastic behavior\nof crosslinked membranes, giving rise to scale-dependent elastic moduli. While\nthermal effects in flat membranes are well understood, many natural and\nartificial microstructures are modeled as thin elastic {\\it shells}. Shells are\ndistinguished from flat membranes by their nonzero curvature, which provides a\nsize-dependent coupling between the in-plane stretching modes and the\nout-of-plane undulations. In addition, a shell can support a pressure\ndifference between its interior and exterior. Little is known about the effect\nof thermal fluctuations on the elastic properties of shells. Here, we study the\nstatistical mechanics of shape fluctuations in a pressurized spherical shell\nusing perturbation theory and Monte Carlo computer simulations, explicitly\nincluding the effects of curvature and an inward pressure. We predict novel\nproperties of fluctuating thin shells under point indentations and\npressure-induced deformations. The contribution due to thermal fluctuations\nincreases with increasing ratio of shell radius to thickness, and dominates the\nresponse when the product of this ratio and the thermal energy becomes large\ncompared to the bending rigidity of the shell. Thermal effects are enhanced\nwhen a large uniform inward pressure acts on the shell, and diverge as this\npressure approaches the classical buckling transition of the shell. Our results\nare relevant for the elasticity and osmotic collapse of microcapsules."
    },
    {
        "anchor": "Boids in a Loop: Self-Propelled particles within a Flexible Boundary: We numerically explore the behavior of repelling and aligning self-propelled\npolar particles (boids) in 2D enclosed by a damped flexible and elastic\nloop-shaped boundary. We observe disordered, polar ordered (or jammed) and\ncirculating states. The latter produce a rich variety of boundary shapes\nincluding; circles, ovals, irregulars, ruffles, or sprockets, depending upon\nthe bending moment of the boundary and the boundary to particle mass ratio.\nWith the exception of the circulating states with non-round boundaries, states\nresemble those exhibited by attracting self-propelled particles, but here the\nconfining boundary acts in place of a cohesive force. We attribute the\nformation of ruffles to instability mediated by pressure on the boundary when\nthe speed of waves on the boundary approximately matches the self-propelled\nparticle's swim speed.",
        "positive": "Electrostatic Attraction between Overall Neutral Surfaces: Two overall neutral surfaces with positive and negative charged domains\n(\"patches\") have been shown in recent experiments to exhibit long-range\nattraction when immersed in an ionic solution. Motivated by the experiments, we\ncalculate analytically the osmotic pressure between such surfaces within the\nPoisson-Boltzmann framework, using a variational principle for the\nsurface-averaged free energy. The electrostatic potential, calculated beyond\nthe linear Debye-H\\\"uckel theory, yields an {\\it overall attraction} at large\ninter-surface separations, over a wide range of the system's controlled length\nscales. In particular, the attraction is stronger and occurs at smaller\nseparations for surface patches of larger size and charge density. In this\nlarge patch limit, we find that the attraction-repulsion crossover separation\nis inversely proportional to the square of the patch charge-density and to the\nDebye screening length."
    },
    {
        "anchor": "Universal scaling of flow curves: comparison between experiments and\n  simulations: Yield stress materials form an interesting class of materials that behave\nlike solids at small stresses, but start to flow once a critical stress is\nexceeded. It has already been reported both in experimental and simulation work\nthat flow curves of different yield stress materials can be scaled with the\ndistance to jamming or with the confining pressure. However, different scaling\nexponents are found between experiments and simulations. In this paper we\nidentify sources of this discrepancy. We numerically relate the volume fraction\nwith the confining pressure and discuss the similarities and differences\nbetween rotational and oscillatory measurements. Whereas simulations are\nperformed in the elastic response regime close to the jamming transition and\nwith very small amplitudes to calculate the scaling exponents, these conditions\nare hardly possible to achieve experimentally. Measurements are often performed\nfar away from the critical volume fraction and at large amplitudes. We show\nthat these differences are the underlying reason for the different exponents\nfor rescaling flow curves.",
        "positive": "Liquid phase fast electron tomography unravels the true 3D structure of\n  colloidal assemblies: Electron tomography has become a commonly used tool to investigate the\nthree-dimensional (3D) structure of nanomaterials, including colloidal\nnanoparticle assemblies. However, electron microscopy is typically carried out\nunder high vacuum conditions. Therefore, pre-treatment sample preparation is\nneeded for assemblies obtained by (wet) colloid chemistry methods, including\nsolvent evaporation and deposition on a solid TEM support. As a result of this\nprocedure, changes are consistently imposed on the actual nanoparticle\norganization. Therefore, we propose herein the application of electron\ntomography of nanoparticle assemblies while in their original colloidal liquid\nenvironment. To address the challenges related to electron tomography in\nliquid, we devised a method that combines fast data acquisition in a commercial\nliquid-TEM cell, with a dedicated alignment and reconstruction workflow. We\npresent the application of this method to two different systems, which\nexemplify the difference between conventional and liquid tomography, depending\non the nature of the protecting ligands. 3D reconstructions of assemblies\ncomprising polystyrene-capped Au nanoparticles encapsulated in polymeric shells\nrevealed less compact and more distorted configurations for experiments\nperformed in a liquid medium compared to their dried counterparts. On the other\nhand, quantitative analysis of the surface-to-surface distance of\nself-assembled Au nanorods in water agrees with previously reported dimensions\nof the ligand layers surrounding the nanorods, which are in much closer contact\nwhen in similar but dried assemblies. This study, therefore, emphasizes the\nimportance of developing high-resolution characterization tools that preserve\nthe native environment of colloidal nanostructures."
    },
    {
        "anchor": "Understanding the Local Flow Rate Peak of a Hopper Discharging Discs\n  through an Obstacle Using a Tetris-like Model: Placing a round obstacle above the orifice of a flat hopper discharging\nuniform frictional discs has been experimentally and numerically shown in the\nliterature to create a local peak in the gravity-driven hopper flow rate. Using\nfrictionless molecular dynamics (MD) simulations, we show that the local peak\nis unrelated to the interparticle friction, the particle dispersity, and the\nobstacle geometry. We then construct a probabilistic Tetris-like model, where\nparticles update their positions according to prescribed rules rather than in\nresponse to forces, and show that Newtonian dynamics are also not responsible\nfor the local peak. Finally, we propose that the local peak is caused by an\ninterplay between the flow rate around the obstacle, greater than the maximum\nwhen the hopper contains no obstacle, and a slow response time, allowing the\noverflowing particles to converge well upon reaching the hopper orifice.",
        "positive": "Drag Coefficient of a Circular Inclusion in a Near-Critical Binary Fluid\n  Membrane: We calculate the drag coefficient of a circular liquid domain, which is put\nin a flat fluid membrane composed of a binary fluid mixture lying in the\nhomogeneous phase near the demixing critical point. Assuming a sufficiently\nsmall correlation length, we regard the domain dynamics as independent of the\ncritical fluctuation and use the Gaussian free-energy functional for the\nmixture. Because of the near-criticality, the preferential attraction between\nthe domain component and one of the mixture components generates the\ncomposition gradient outside the domain significantly and can affect the drag\ncoefficient. We first consider a domain having the same membrane viscosity as\nthe domain exterior. The drag coefficient is expanded with respect to a\ndimensionless strength of the preferential attraction. It is numerically shown\nthat the magnitude of the expansion coefficient decreases much as the order of\nthe strength increases and that the first-order term of the series usually\ngives a good approximation for practical material constants. The effect of the\npreferential attraction is shown to be able to become significantly large in\npractice. We second consider cases where the membrane viscosities of the domain\ninterior and exterior are different. The first-order term of the expansion\nseries decreases to approach zero as the domain viscosity increases to\ninfinity. This agrees with previous numerical results showing that the\nhydrodynamics makes the effect of the preferential attraction negligibly small\nfor a rigid disk."
    },
    {
        "anchor": "A sidewall friction driven ordering transition in granular channel\n  flows: Implications for granular rheology: We report a transition from a disordered state to an ordered state in the\nflow of nearly mono-disperse granular matter flowing in an inclined channel\nwith a bumpy base, in discrete element method simulations. For low\nparticle-sidewall friction coefficients, the particles are disordered and the\nBagnold velocity profile is obtained. However, for high sidewall friction, an\nordered state is obtained, characterized by a layering of the particles and\nhexagonal packing of the particles in each layer. The extent of ordering,\nquantified by the local bond-orientational order parameter, varies in the\ncross- section of the channel, with the highest ordering near the side walls.\nThe flow transition significantly affects the local rheology: the effective\nfriction coefficient is lower, and the packing fraction is higher, in the\nordered state compared to the disordered state. A simple model, incorporating\nthe extent of local ordering, is shown to describe the rheology of the system.",
        "positive": "Non-local rheology in dense granular flows -- Revisiting the concept of\n  fluidity: The aim of this article is to discuss the concepts of non-local rheology and\nfluidity, recently introduced to describe dense granular flows. We review and\ncompare various approaches based on different constitutive relations and\nchoices for the fluidity parameter, focusing on the kinetic elasto-plastic\nmodel introduced by Bocquet et al. [Phys. Rev. Lett 103, 036001 (2009)] for\nsoft matter, and adapted for granular matter by Kamrin et al. [Phys. Rev. Lett.\n108, 178301 (2012)], and the gradient expansion of the local rheology $\\mu(I)$\nthat we have proposed [Phys. Rev. Lett. 111, 238301 (2013)]. We emphasise that,\nto discriminate between these approaches, one has to go beyond the predictions\nderived from linearisation around a uniform stress profile, such as that\nobtained in a simple shear cell. We argue that future tests can be based on the\nnature of the chosen fluidity parameter, and the related boundary conditions,\nas well as the hypothesis made to derive the models and the dynamical\nmechanisms underlying their dynamics."
    },
    {
        "anchor": "Hydrodynamics of fluid-solid coexistence in dense shear granular flow: We consider dense rapid shear flow of inelastically colliding hard disks.\nNavier-Stokes granular hydrodynamics is applied accounting for the recent\nfinding \\cite{Luding,Khain} that shear viscosity diverges at a lower density\nthan the rest of constitutive relations. New interpolation formulas for\nconstitutive relations between dilute and dense cases are proposed and\njustified in molecular dynamics (MD) simulations. A linear stability analysis\nof the uniform shear flow is performed and the full phase diagram is presented.\nIt is shown that when the inelasticity of particle collision becomes large\nenough, the uniform sheared flow gives way to a two-phase flow, where a dense\n\"solid-like\" striped cluster is surrounded by two fluid layers. The results of\nthe analysis are verified in event-driven MD simulations, and a good agreement\nis observed.",
        "positive": "Time Resolved Correlation measurements of temporally heterogeneous\n  dynamics: Time Resolved Correlation (TRC) is a recently introduced light scattering\ntechnique that allows to detect and quantify dynamic heterogeneities. The\ntechnique is based on the analysis of the temporal evolution of the speckle\npattern generated by the light scattered by a sample, which is quantified by\n$c\\_I(t,\\tau)$, the degree of correlation between speckle images recorded at\ntime $t$ and $t+\\tau$. Heterogeneous dynamics results in significant\nfluctuations of $c\\_I(t,\\tau)$ with time $t$. We describe how to optimize TRC\nmeasurements and how to detect and avoid possible artifacts. The statistical\nproperties of the fluctuations of $c\\_I$ are analyzed by studying their\nvariance, probability distribution function, and time autocorrelation function.\nWe show that these quantities are affected by a noise contribution due to the\nfinite number $N$ of detected speckles. We propose and demonstrate a method to\ncorrect for the noise contribution, based on a $N\\to \\infty$ extrapolation\nscheme. Examples from both homogeneous and heterogeneous dynamics are provided.\nConnections with recent numerical and analytical works on heterogeneous glassy\ndynamics are briefly discussed."
    },
    {
        "anchor": "Electric field Induced Patterns in Soft Visco-elastic films: From Long\n  Waves of Viscous Liquids to Short Waves of Elastic Solids: We show that the electric field driven surface instability of visco-elastic\nfilms has two distinct regimes: (1) The visco-elastic films behaving like a\nliquid display long wavelengths governed by applied voltage and surface\ntension, independent of its elastic storage and viscous loss moduli, and (2)\nthe films behaving like a solid require a threshold voltage for the instability\nwhose wavelength always scales as ~ 4 x film thickness, independent of its\nsurface tension, applied voltage, loss and storage moduli. Wavelength in a\nnarrow transition zone between these regimes depends on the storage modulus.",
        "positive": "Stability analysis of charge-controlled soft dielectric plates: We examine the stability of a soft dielectric plate deformed by the coupled\neffects of a mechanical pre-stress applied on its lateral faces and an electric\nfield applied through its thickness under charge control. The electric field is\ncreated by spraying charges on the major faces of the plate: although in\npractice this mode of actuation is harder to achieve than a voltage-driven\ndeformation, here we find that it turns out to be much more stable in theory\nand in simulations.\n  First we show that the electromechanical instability based on the Hessian\ncriterion associated with the free energy of the system does not occur at all\nfor charge-driven dielectrics for which the electric displacement is linear in\nthe electric field. Then we show that the geometric instability associated with\nthe formation of small-amplitude wrinkles on the faces of the plate that arises\nunder voltage control does not occur either under charge control. This is in\ncomplete contrast to voltage-control actuation, where Hessian and wrinkling\ninstabilities can occur once certain critical voltages are reached.\n  For the mechanical pre-stresses, two modes that can be implemented in\npractice are used: equi-biaxial and uni-axial. We confirm the analytical and\nnumerical stability results of homogeneous deformation modes with Finite\nElement simulations of real actuations, where inhomogeneous fields may develop.\nWe find complete agreement in the equi-biaxial case, and very close agreement\nin the uni-axial case, when the pre-stress is due to a dead-load weight. In the\nlatter case, the simulations show that small inhomogeneous effects develop near\nthe clamps, and eventually a compressive lateral stress emerges, leading to a\nbreakdown of the numerics."
    },
    {
        "anchor": "Numerical study of the spherically-symmetric Gross-Pitaevskii equation\n  in two space dimensions: We present a numerical study of the time-dependent and time-independent\nGross-Pitaevskii (GP) equation in two space dimensions, which describes the\nBose-Einstein condensate of trapped bosons at ultralow temperature with both\nattractive and repulsive interatomic interactions. Both time-dependent and\ntime-independent GP equations are used to study the stationary problems. In\naddition the time-dependent approach is used to study some evolution problems\nof the condensate. Specifically, we study the evolution problem where the trap\nenergy is suddenly changed in a stable preformed condensate. In this case the\nsystem oscillates with increasing amplitude and does not remain limited between\ntwo stable configurations. Good convergence is obtained in all cases studied.",
        "positive": "A Fragile-Strong Fluid Crossover and Universal Relaxation Times in a\n  Confined Hard Disc Fluid: We show that a system of hard discs confined to a narrow channel exhibits a\nfragile-strong fluid crossover located at the maximum of the isobaric heat\ncapacity and that the relaxation times for different channel widths fall onto a\nsingle master curve when rescaled by the relaxation times and temperatures of\nthe crossover. Calculations of the configurational entropy and the inherent\nstructure equation of state find that the crossover is related to properties of\nthe jamming landscape for the model but that the Adams-Gibbs relation does not\npredict the relaxation behavior. We also show that a facilitated dynamics\ndescription of the system, where kinetically excited regions are identified\nwith local packing arrangements of the discs, successfully describes the\nfragile-strong crossover."
    },
    {
        "anchor": "Machine-learning techniques for fast and accurate feature localization\n  in holograms of colloidal particles: Holograms of colloidal particles can be analyzed with the Lorenz-Mie theory\nof light scattering to measure individual particles' three-dimensional\npositions with nanometer precision while simultaneously estimating their sizes\nand refractive indexes. Extracting this wealth of information begins by\ndetecting and localizing features of interest within individual holograms.\nConventionally approached with heuristic algorithms, this image analysis\nproblem can be solved faster and more generally with machine-learning\ntechniques. We demonstrate that two popular machine-learning algorithms,\ncascade classifiers and deep convolutional neural networks (CNN), can solve the\nfeature-localization problem orders of magnitude faster than current\nstate-of-the-art techniques. Our CNN implementation localizes holographic\nfeatures precisely enough to bootstrap more detailed analyses based on the\nLorenz-Mie theory of light scattering. The wavelet-based Haar cascade proves to\nbe less precise, but is so computationally efficient that it creates new\nopportunities for applications that emphasize speed and low cost. We\ndemonstrate its use as a real-time targeting system for holographic optical\ntrapping.",
        "positive": "Three-Sphere Low Reynolds Number Swimmer with a Cargo Container: A recently introduced model for an autonomous swimmer at low Reynolds number\nthat is comprised of three spheres connected by two arms is considered when one\nof the spheres has a large radius. The Stokes hydrodynamic flow associated with\nthe swimming strokes and net motion of this system can be studied analytically\nusing the Stokes Green's function of a point force in front of a sphere of\narbitrary radius $R$ provided by Oseen. The swimming velocity is calculated,\nand shown to scale as $1/R^3$ with the radius of the sphere."
    },
    {
        "anchor": "Interfacial friction between semiflexible polymers and crystalline\n  surfaces: The results obtained from molecular dynamics simulations of the friction at\nan interface between polymer melts and weakly attractive crystalline surfaces\nare reported. We consider a coarse-grained bead-spring model of linear chains\nwith adjustable intrinsic stiffness. The structure and relaxation dynamics of\npolymer chains near interfaces are quantified by the radius of gyration and\ndecay of the time autocorrelation function of the first normal mode. We found\nthat the friction coefficient at small slip velocities exhibits a distinct\nmaximum which appears due to shear-induced alignment of semiflexible chain\nsegments in contact with solid walls. At large slip velocities the decay of the\nfriction coefficient is independent of the chain stiffness. The data for the\nfriction coefficient and shear viscosity are used to elucidate main trends in\nthe nonlinear shear rate dependence of the slip length. The influence of chain\nstiffness on the relationship between the friction coefficient and the\nstructure factor in the first fluid layer is discussed.",
        "positive": "Precipitation of water from aqueous mixtures with addition of\n  hydrophilic ions: We examine phase separation in aqueous mixtures at fixed amounts of\nhydrophilic monovalent ions. When water is the minority component, preferential\nsolvation can stabilize water domains enriched with ions.\n  This ion-induced precipitation occurs in wide ranges of the temperature and\nthe average composition where the solvent would be in one-phase states without\nions. The volume fraction of such water domains is decreased to zero as the\ninteraction parameter $\\chi$ (dependent on the temperature) is decreased toward\na critical value for each average composition."
    },
    {
        "anchor": "Reversible Transient Nucleation in Ionic Solutions as the Precursor of\n  Ion Crystallization: Molecular dynamics simulations for aqueous sodium chloride solutions were\ncarried out at various concentrations. Supplementary to the Debye-H\\\"uckel\ntheory, reversible transient nucleation of ions was observed even in dilute\nsolutions. The average size of formed ion clusters and the lifetime of ion\npairs increase with concentration until the saturation point, when ion clusters\nbecome stable and individual ions adjust their positions to form ordered\nlattice structures, leading to irreversible ion crystallization, which is\nbeyond the description of the classical nucleation theory.",
        "positive": "Dynamic particle tracking reveals the aging temperature of a colloidal\n  glass: Understanding glasses is considered to be one of the most fundamental\nproblems in statistical physics. A theoretical approach to unravel their\nuniversal properties is to consider the validity of equilibrium concepts such\nas temperature and thermalization in these out-of-equilibrium systems. Here we\ninvestigate the autocorrelation and response function to monitor the aging of a\ncolloidal glass. At equilibrium, all the observables are stationary while in\nthe out-of-equilibrium glassy state they have an explicit dependence on the age\nof the system. We find that the transport coefficients scale with the\naging-time as a power-law, a signature of the slow relaxation. Nevertheless,\nour analysis reveals that the glassy system has thermalized at a constant\ntemperature independent of the age and larger than the bath, reflecting the\nstructural rearrangements of cage-dynamics. Furthermore, a universal scaling\nlaw is found to describe the global and local fluctuations of the observables."
    },
    {
        "anchor": "Birthing of a daughter vesicle in a model system for self-reproduction\n  vesicles: Sakuma and Imai [Phys. Rev. Lett. 107, 198101 (2011)] established a\ntemperature-controlled cyclic process for a model system of self-reproducing\nvesicles without feeding. The vesicle generates a smaller inclusion vesicle\ncalled \"daughter vesicle\" inside the original vesicle (we call this \"mother\nvesicle\") and then the daughter vesicle is expelled through a small pore on the\nmother vesicle. This self-reproducing process is called birthing. In the\npresent study we present theoretical model on the birthing process of a single,\nrigid daughter vesicle through a pore. By using a simple geometric picture, we\nderive the free energy constituting the material properties of the bending,\nstretching and line tension moduli of the mother vesicle, as a function of the\ndistance between the centers of the daughter and mother vesicles, and the size\nof the daughter vesicle. We see clearly the disappearance of the energy barrier\nby selecting appropriate moduli. The dynamics of the system is studied by\nemploying the Onsager principle. The results indicate that translocation time\ndecreases as the friction parameter decreases, or the initial size of the\ndaughter vesicle decreases.",
        "positive": "Brush in the bath of active particles: anomalous stretching of chains\n  and distribution of particles: The interaction between polymer brush and colloidal particles has been\nintensively studied in the last two decades. Here we consider a flat\nchain-grafted substrate immersed in a bath of active particles. Simulations\nshow that an increase in the self-propelling force causes an increase in the\nnumber of particles that penetrate into the brush. Anomalously, the particle\ndensity inside the main body of the brush eventually becomes higher than that\noutside the brush at very large self-propelling force. The grafted chains are\nfurther stretched due to the steric repulsion from the intruded particles. Upon\nthe increase of the self-propelling force, distinct stretching behaviors of\nchains were observed for low and high grafting densities. Surprisingly, we\nfound a weak descent of the end-to-end distance of chains for high grafting\ndensity and very large force which is reminiscent of the compression effect of\na chain in the active bath."
    },
    {
        "anchor": "Structure and thermodynamics of a mixture of patchy and spherical\n  colloids: a multi-body association theory with complete reference fluid\n  information: A mixture of solvent particles with short-range, directional interactions and\nsolute particles with short-range, isotropic interactions that can bond\nmultiple times is of fundamental interest in understanding liquids and\ncolloidal mixtures. Because of multi-body correlations predicting the structure\nand thermodynamics of such systems remains a challenge. Earlier Marshall and\nChapman developed a theory wherein association effects due to interactions\nmultiply the partition function for clustering of particles in a reference\nhard-sphere system. The multi-body effects are incorporated in the clustering\nprocess, which in their work was obtained in the absence of the bulk medium.\nThe bulk solvent effects were then modeled approximately within a second order\nperturbation approach. However, their approach is inadequate at high densities\nand for large association strengths. Based on the idea that the clustering of\nsolvent in a defined coordination volume around the solute is related to\noccupancy statistics in that defined coordination volume, we develop an\napproach to incorporate the complete information about hard-sphere clustering\nin a bulk solvent at the density of interest. The occupancy probabilities are\nobtained from enhanced sampling simulations but we also develop a concise\nparametric form to model these probabilities using the quasichemical theory of\nsolutions. We show that incorporating the complete reference information\nresults in an approach that can predict the bonding state and thermodynamics of\nthe colloidal solute for a wide range of system conditions.",
        "positive": "Orientational order and morphology of clusters of self-assembled Janus\n  swimmers: Due to the combined effect of anisotropic interactions and activity, Janus\nswimmers are capable to self-assemble in a wide variety of structures, many\nmore than their equilibrium counterpart. This might lead to the development of\nnovel active materials capable of performing tasks without any central control.\nTheir potential application in designing such materials endows trying to\nunderstand the fundamental mechanism in which these swimmers self-assemble. In\nthe present work, we study a quasi-two dimensional semi-dilute suspensions of\ntwo classes of amphiphilic spherical swimmers whose direction of motion can be\ntuned: either swimmers propelling in the direction of the hydrophobic patch\n(WP), or swimmers propelling in the opposite direction (towards the hydrophilic\nside) (AP). In both systems we have systematically tuned swimmers' hydrophobic\nstrength and signature, and observed that the anisotropic interactions,\ncharacterized by the angular attractive potential and its interaction range, in\ncompetition with the active stress, pointing towards or against the attractive\npatch gives rise to a rich aggregation phenomenology."
    },
    {
        "anchor": "Electric field-induced interfacial instability in a ferroelectric\n  nematic liquid crystal: Studies of sessile droplets and fluid bridges of a ferroelectric nematic\nliquid crystal in externally applied electric fields are presented. It is found\nthat above a threshold, the interface of the fluid with air undergoes a\nfingering instability or ramification, resembling to Rayleigh-type instability\nobserved in charged droplets in electric fields or circular drop-type\ninstabilities observed in ferromagnetic liquids in magnetic field. The\nfrequency dependence of the threshold voltage was determined in various\ngeometries. The nematic director and ferroelectric polarization direction was\nfound to point along the tip of the fingers that appear to repel each other,\nindicating that the ferroelectric polarization is essentially parallel to the\ndirector. The results are interpreted in connection to the Rayleigh and\ncircular drop-type instabilities.",
        "positive": "Bethe-lattice calculations for the phase diagram of a two-state Janus\n  gas: We use a simple lattice statistical model to analyze the effects of\ndirectional interactions on the phase diagram of a fluid of two-state Janus\nparticles. The problem is formulated in terms of nonlinear recursion relations\nalong the branches of a Cayley tree. Directional interactions are taken into\naccount by the geometry of this graph. Physical solutions on the Bethe lattice\n(the deep interior of a Cayley tree) come from the analysis of the attractors\nof the recursion relations. We investigate a number of situations, depending on\nthe concentrations of the types of Janus particles and the parameters of the\npotential, and make contact with results from recent numerical simulations."
    },
    {
        "anchor": "Dynamic percolation theory for particle diffusion in a polymer network: Tracer-diffusion of small molecules through dense systems of chain polymers\nis studied within an athermal lattice model, where hard core interactions are\ntaken into account by means of the site exclusion principle. An approximate\nmapping of this problem onto dynamic percolation theory is proposed. This\nmethod is shown to yield quantitative results for the tracer correlation factor\nof the molecules as a function of density and chain length provided the\nnon-Poisson character of temporal renewals in the disorder configurations is\nproperly taken into account.",
        "positive": "Regimes of Wetting Transitions on Superhydrophobic Textures Conditioned\n  by Energy of Receding Contact Lines: We discuss an evaporation-induced wetting transition on superhydrophobic\nstripes, and show that depending on the elastic energy of the deformed contact\nline, which determines the value of an instantaneous effective contact angle,\ntwo different scenarios occur. For relatively dilute stripes the receding angle\nis above 90$^\\circ$, and the sudden impalement transition happens due to an\nincrease of a curvature of an evaporating drop. For dense stripes the slow\nimpregnation transition commences when the effective angle reaches 90$^\\circ$\nand represents the impregnation of the grooves from the triple contact line\ntowards the drop center."
    },
    {
        "anchor": "Migration reversal of soft particles in vertical flows: Non-neutrally buoyant soft particles in vertical microflows are investigated.\nWe find, soft particles lighter than the liquid migrate to off-center\nstreamlines in a downward Poiseuille flow (buoyancy-force antiparallel to\nflow). In contrast, heavy soft particles migrate to the center of the downward\n(and vanishing) Poiseuille flow. A reversal of the flow direction causes in\nboth cases a reversal of the migration direction, i. e. heavier (lighter)\nparticles migrate away from (to) the center of a parabolic flow profile.\nNon-neutrally buoyant particles migrate also in a linear shear flow across the\nparallel streamlines: heavy (light) particles migrate along (antiparallel to)\nthe local shear gradient. This surprising, flow-dependent migration is\ncharacterized by simulations and analytical calculations for small particle\ndeformations, confirming our plausible explanation of the effect. This density\ndependent migration reversal may be useful for separating particles.",
        "positive": "Steady energy transfer dependence granular temperature on single\n  bouncing granular particle: Simulation of a system consisted of free particle bouncing on a vertically\nvibrated based is performed. Two different states, which are steady and\nunsteady energy transfer state are found. The vibrating based is hold at\nconstant vibration frequency $f = 0.1$ as the vibration amplitude $A$ varied.\nSinusoidal form is used. Granular temperature $T_g$ as function of based\nvelocity and coefficient of restitution is used but shown no role in\ndetermining energy transfer state of the system. Peak of free particle\ntrajectory $x_m$ around value 20 seperate region of the two states."
    },
    {
        "anchor": "Topology of orientational defects in confined smectic liquid crystals: We propose a general formalism to characterize orientational frustration of\nsmectic liquid crystals in confinement by interpreting the emerging networks of\ngrain boundaries as objects with a topological charge. In a formal\nidealization, this charge is distributed in point-like units of quarter-integer\nmagnitude, which we identify with tetratic disclinations located at the end\npoints and nodes. This coexisting nematic and tetratic order is analyzed with\nthe help of extensive Monte Carlo simulations for a broad range of\ntwo-dimensional confining geometries as well as colloidal experiments, showing\nhow the observed defect networks can be universally reconstructed from simple\nbuilding blocks. We further find that the curvature of the confining wall\ndetermines the anchoring behavior of grain boundaries, such that the number of\nnodes in the emerging networks and the location of their end points can be\ntuned by changing the number and smoothness of corners, respectively.",
        "positive": "Classifying soft self-assembled materials via unsupervised machine\n  learning of defects: Unlike molecular crystals, soft self-assembled fibres, micelles, vesicles,\netc., exhibit a certain order in the arrangement of their constitutive\nmonomers, but also high structural dynamicity and variability. Defects and\ndisordered local domains that continuously form-and-repair in their structures\nimpart to such materials unique adaptive and dynamical properties, which make\nthem, e.g., capable to communicate with each other. However, objective criteria\nto compare such complex dynamical features and to classify soft supramolecular\nmaterials are non-trivial to attain. Here we show a data-driven workflow\nallowing us to achieve this goal. Building on unsupervised clustering of Smooth\nOverlap of Atomic Position (SOAP) data obtained from equilibrium molecular\ndynamics simulations, we can compare a variety of soft supramolecular\nassemblies via a robust SOAP metric. This provides us with a data-driven\n\"defectometer\" to classify different types of supramolecular materials based on\nthe structural dynamics of the ordered/disordered local molecular environments\nthat statistically emerge within them."
    },
    {
        "anchor": "Maximum disorder model for dense steady-state flow of granular materials: A flow model is developed for dense shear-driven granular flow. As described\nin the geomechanics literature, a critical state condition is reached after\nsufficient shearing beyond an initial static packing. During further shearing\nat the critical state, the stress, fabric, and density remain nearly constant,\neven as particles are being continually rearranged. The paper proposes a\npredictive framework for critical state flow, viewing it as a condition of\nmaximum disorder at the micro-scale. The flow model is constructed in a\ntwo-dimensional setting from the probability density of the motions, forces,\nand orientations of inter-particle contacts. Constraints are applied to this\nprobability density: constant mean stress, constant volume, consistency of the\ncontact dissipation rate with the stress work, and the fraction of sliding\ncontacts. The differential form of Shannon entropy, a measure of disorder, is\napplied to the density, and the Jaynes formalism is used to find the density of\nmaximum disorder in the underlying phase space. The resulting distributions of\ncontact force, movement, and orientation are compared with two-dimensional DEM\nsimulations of biaxial compression. The model favorably predicts anisotropies\nof the contact orientations, contact forces, contact movements, and the\norientations of those contacts undergoing slip. The model also predicts the\nrelationships between contact force magnitude and contact motion. The model is\nan alternative to affine-field descriptions of granular flow.",
        "positive": "Effect of an external magnetic field on the nematic-isotropic phase\n  transition in mesogenic systems of uniaxial and biaxial molecules: Influence of an external magnetic field on the nematic-isotropic ($N-I$)\nphase transition in a dispersion model of nematic liquid crystals, where the\nmolecules are either perfectly uniaxial or biaxial (board-like), has been\nstudied by Monte Carlo simulation. Using multiple histogram reweighting\ntechnique and finite size scaling analysis the order of the phase transition,\nthe transition temperature at the thermodynamic limit and the stability limit\nof the isotropic phase below the transition temperature for different magnetic\nfield strengths have been determined. The magnetic field dependence of the\nshift in $N-I$ transition temperature is observed to be more rapid than that\npredicted by the standard Landau-de Gennes and Maier-Saupe mean field theories.\nWe have shown that for a given field strength the shift in the transition\ntemperature is higher for the biaxial molecules in comparison with the uniaxial\ncase. The study shows that the $N-I$ transition for the biaxial molecules is\nweaker than the well known weak first order $N-I$ transition for the uniaxial\nmolecules and the presence of the external magnetic field (up to a certain\ncritical value) makes the transition much more weaker for both the systems. The\nestimate of the critical magnetic field ($\\sim 110 T$) for the common nematics\nis found to be smaller than the earlier estimates."
    },
    {
        "anchor": "Dynamic Overlap Concentration Scale of Active Colloids: By introducing the notion of a dynamic overlap concentration scale, we\nidentify universal and previously unreported features of the mechanical\nproperties of active colloids. These features are codified by recognizing that\nthe characteristic length scale of an active particle's trajectory, the\nrun-length, introduces a new concentration scale $\\phi^*$. Large-scale\nsimulations of repulsive active Brownian particles (ABPs) confirm that this new\nrun-length dependent concentration, which is the trajectory-space analogue of\nthe overlap concentration in polymer solutions, delineates distinct\nconcentration regimes in which interparticle collisions alter particle\ntrajectories. Using $\\phi^*$ and concentration scales associated with colloidal\njamming, the mechanical equation-of-state for ABPs can be collapsed onto a set\nof principal curves that contain a number of previously overlooked features.\nThe inclusion of these features qualitatively alters previous predictions of\nthe behavior for active colloids as we demonstrate by computing the spinodal\nfor a suspension of purely-repulsive ABPs. Our findings suggest that dynamic\noverlap concentration scales should be of great utility in unraveling the\nbehavior of active and driven systems.",
        "positive": "Crunching Biofilament Rings: We discuss a curious example for the collective mechanical behavior of\ncoupled non-linear monomer units entrapped in a circular filament. Within a\nsimple model we elucidate how multistability of monomer units and exponentially\nlarge degeneracy of the filament's ground state emerge as a collective feature\nof the closed filament. Surprisingly, increasing the monomer frustration, i.e.,\nthe bending prestrain within the circular filament, leads to a conformational\nsoftening of the system. The phenomenon, that we term polymorphic crunching, is\ndiscussed and applied to a possible scenario for membrane tube deformation by\nswitchable dynamin or FtsZ filaments. We find an important role of cooperative\ninter-unit interaction for efficient ring induced membrane fission."
    },
    {
        "anchor": "Derivation of the Inverse Schulze-Hardy Rule: The inverse Schulze-Hardy rule was recently proposed based on experimental\nobservations (Cao et al., Langmuir, 2015, 31, 6610-6614). This rule describes\nan interesting new situation of the aggregation of charged colloidal particles\nin the presence of the multivalent coions. Specifically, it can be shown that\nthe critical coagulation concentration is inversely proportional to the coion\nvalence. Here the derivation of the inverse Schulze-Hardy rule based on purely\ntheoretical grounds is presented for the first time. This derivation\ncomplements the classical Schulze-Hardy rule which describes the multivalent\ncounterion systems.",
        "positive": "Supercooling and freezing processes in nanoconfined water by\n  time-resolved optical Kerr effect spectroscopy: Using heterodyne-detected optical Kerr effect (HD-OKE) measurements, we\ninvestigate the vibrational dynamics and the structural relaxation of water\nnanoconfined in Vycor porous silica samples (pore size $\\simeq~4~nm$ ) at\ndifferent levels of hydration and temperatures. At low level of hydration,\ncorresponding to two complete superficial water layers, no freezing occurs and\nwater remains mobile at all the investigated temperatures with dynamic features\nsimilar, but not equal, to the bulk water. The fully hydrated sample shows\nformation of ice at about 248 K, this process does not involve all the\ncontained water; a part of it remains in a supercooled phase. The structural\nrelaxation times measured from the decay of the time-dependent HD-OKE signal\nshows temperature dependence largely affected by the hydration level; the low\nfrequency ($\\nu<500~cm^{-1}$) vibrational spectra, obtained by the Fourier\ntransforms of HD-OKE signal, appears less affected by confinement."
    },
    {
        "anchor": "Shape selection of surface-bound helical filaments: biopolymers on\n  curved membranes: Motivated to understand the behavior of biological filaments interacting with\nmembranes of various types, we study a theoretical model for the shape and\nthermodynamics of intrinsically-helical filaments bound to curved membranes. We\nshow filament-surface interactions lead to a host of non-uniform shape\nequilibria, in which filaments progressively unwind from their native twist\nwith increasing surface interaction and surface curvature, ultimately adopting\nuniform-contact curved shapes. The latter effect is due to non-linear coupling\nbetween elastic twist and bending of filaments on anisotropically-curved\nsurfaces, such as the cylindrical surfaces considered here. Via a combination\nof numerical solutions and asymptotic analysis of shape equilibria we show that\nfilament conformations are critically sensitive to the surface curvature in\nboth the strong- and weak-binding limits. These results suggest that local\nstructure of membrane-bound chiral filaments is generically sensitive to the\ncurvature-radius of the surface to which it is bound, even when that radius is\nmuch larger than the filament intrinsic pitch. Typical values of elastic\nparameters and interaction energies for several prokaryotic and eukaryotic\nfilaments indicate that biopolymers are inherently very sensitive to the\ncoupling between twist, interactions and geometry and that this could be\nexploited for regulation of a variety of processes such as the targeted\nexertion of forces, signaling and self-assembly in response to geometric cues\nincluding the local mean and Gaussian curvatures.",
        "positive": "Phase behaviour of DNA in presence of DNA-binding proteins: To characterize the thermodynamical equilibrium of DNA chains interacting\nwith a solution of non-specific binding proteins, a Flory-Huggins free energy\nmodel was implemented. We explored the dependence on DNA and protein\nconcentrations of the DNA collapse. For physiologically relevant values of the\nDNA-protein affinity, this collapse gives rise to a biphasic regime with a\ndense and a dilute phase; the corresponding phase diagram was computed. Using\nan approach based on Hamiltonian paths, we show that the dense phase has either\na molten globule or a crystalline structure, depending on the DNA bending\nrigidity, which is influenced by the ionic strength. These results are valid at\nthe thermodynamical equilibrium and should therefore be consistent with many\nbiological processes, whose characteristic timescales range typically from 1 ms\nto 10 s. Our model may thus be applied to biological phenomena that involve\nDNA-binding proteins, such as DNA condensation with crystalline order, which\noccurs in some bacteria to protect their chromosome from detrimental factors;\nor transcription initiation, which occurs in clusters called transcription\nfactories that are reminiscent of the dense phase characterized in this study."
    },
    {
        "anchor": "Trajectories of directed lattice paths: The distribution of monomers along a linear polymer grafted on a hard wall is\nmodelled by determining the probability distribution of occupied vertices of\nDyck and ballot path models of adsorbing linear polymers. For example, the\nprobability that a Dyck path passes through the lattice site with coordinates\n$(\\lfloor \\epsilon n \\rfloor,\\lfloor \\delta \\sqrt{n}\\rfloor)$ in the square\nlattice, for $0 < \\epsilon < 1$ and $\\delta\\geq 0$, is determined\nasymptotically as $n\\to\\infty$ and this uncovers the probability density of\nvertices along Dyck paths in the limit as the length of the path $n$ approaches\ninfinity: $$\\hbox{P}_r (\\epsilon,\\delta) =\n\\frac{4\\delta^2}{\\sqrt{\\pi\\,\\epsilon^3(1-\\epsilon)^3}} \\,\ne^{-\\delta^2/\\epsilon(1-\\epsilon)}\\ .$$ The properties of a polymer coating of\na hard wall and the density or distribution of monomers in the coating is\nrelevant in applications such as the stabilisation of a colloid dispersion by a\npolymer or in a drug delivery system such as a drug-eluding stent covered by a\ngrafted polymer.",
        "positive": "Designing recipes for auxetic behaviour of 2-d lattices: We present an analytical model to investigate the mechanics of 2-dimensional\nlattices composed of elastic beams of non-uniform cross-section. Our approach\nis based on reducing a lattice to a single beam subject to the action of a set\nof linear and torsional springs, thus allowing the problem to be solved through\na transfer matrix method. We show a non-trivial region of design space that\nyields materials with auxetic properties for strains greater than that required\nto trigger elastic instability. The critical loading required to make this\ntransition from positive to negative Poisson's ratio is calculated.\nFurthermore, we present lattice parameters that provide direction-dependent\ndeformation modes offering great tailorability of the mechanical properties of\nfinite size lattices. Not only is our analytical formulation in good agreement\nwith the finite element simulation results, but it provides an insight into the\nrole of the interplay between structure and elastic instability, and gives an\nefficient methodology to pursue questions of rational design in the field of\nmechanical metamaterials."
    },
    {
        "anchor": "Evolution of Internal Granular Structure at the Flow-Arrest Transition: The evolution of the internal granular structure in shear-arrested and\nshear-flowing states of granular materials is characterized using fabric\ntensors as descriptors of the internal contact and force networks. When a\ndilute system of frictional grains is subjected to a constant pressure and\nshear stress, the bulk stress ratio is well-predicted from the anisotropy of\nits contact and force networks during transient flow prior to steady shear flow\nor shear arrest. Although the onset of shear arrest is a stochastic process,\nthe fabric tensors upon arrest are distributed around nearly equal\ncontributions of force and contact network anisotropy to the bulk stress ratio.\nThe distribution becomes seemingly narrower with increasing system size. The\nanisotropy of the contact network in shear-arrested states is reminiscent of\nthe fabric anisotropy observed in shear-jammed packings.",
        "positive": "Non-equilibrium configurations of swelling polymer brush layers induced\n  by spreading drops of weakly volatile oil: Polymer brush layers are responsive materials that swell in contact with good\nsolvents and their vapors. We deposit drops of an almost completely wetting\nvolatile oil onto an oleophilic polymer brush layer and follow the response of\nthe system upon simultaneous exposure to both liquid and vapor. Interferometric\nimaging shows that a halo of partly swollen polymer brush layer forms ahead of\nthe moving contact line. The swelling dynamics of this halo is controlled by a\nsubtle balance of direct imbibition from the drop into the brush layer and\nvapor phase transport and can lead to very long-lived transient swelling\nprofiles as well as non-equilibrium configurations involving thickness\ngradients in a stationary state. A gradient dynamics model based on a free\nenergy functional with three coupled fields is developed and numerically\nsolved. It describes experimental observations and reveals how local\nevaporation and condensation conspire to stabilize the inhomogeneous\nnon-equilibrium stationary swelling profiles. A quantitative comparison of\nexperiments and calculations provides access to the solvent diffusion\ncoefficient within the brush layer. Overall, the results highlight the -\npresumably generally applicable - crucial role of vapor phase transport in\ndynamic wetting phenomena involving volatile liquids on swelling functional\nsurfaces."
    },
    {
        "anchor": "Self-propelled Worm-like Filaments: Spontaneous Spiral Formation,\n  Structure, and Dynamics: Worm-like filaments that are propelled homogeneously along their tangent\nvector are studied by Brownian dynamics simulations. Systems in two dimensions\nare investigated, corresponding to filaments adsorbed to interfaces or\nsurfaces. A large parameter space covering weak and strong propulsion, as well\nas flexible and stiff filaments is explored. For strongly propelled and\nflexible filaments, the free-swimming filaments spontaneously form stable\nspirals. The propulsion force has a strong impact on dynamic properties, such\nas the rotational and translational mean square displacement and the rate of\nconformational sampling. In particular, when the active self-propulsion\ndominates thermal diffusion, but is too weak for spiral formation, the\nrotational diffusion coefficient has an activity-induced contribution given by\n$v_c/\\xi_P$, where $v_c$ is the contour velocity and $\\xi_P$ the persistence\nlength. In contrast, structural properties are hardly affected by the activity\nof the system, as long as no spirals form. The model mimics common features of\nbiological systems, such as microtubules and actin filaments on motility assays\nor slender bacteria, and artificially designed microswimmers.",
        "positive": "A Two-State Picture of Water and the Funnel of Life: Here I show that experimental and simulation data on liquid water using\nvibrational (infrared and Raman) and X-ray (absorption and emission)\nspectroscopies, as well as recent data from X-ray scattering, are fully\nconsistent with a two-state picture of water. At ambient conditions there are\nfluctuations between a dominating high-density liquid (HDL) and a low-density\nform (LDL). These are related to the two forms of amorphous ice at very low\ntemperature, high-density amorphous (HDA) and low-density amorphous (LDA),\nwhich interconvert in a first-order-like transition. This transition line is\nassumed to continue into the so-called No-mans land as a liquid-liquid\ntransition and terminate in a critical point with very large fluctuations\nbetween the two liquid forms. These fluctuations extend in a funnel-like region\nup to ambient temperatures and pressures and give water its unusual properties\nwhich are fundamental to life. With this picture we find simple, intuitive\nexplanations of the anomalous properties of water, such as the density maximum\nat 4 C, why ice floats, and why the compressibility and heat capacity grow as\nthe liquid is cooled. We summarize by noting that in this picture, water is not\na complicated liquid, but two normal liquids with a complicated relationship."
    },
    {
        "anchor": "Scattering by source-type flows in disordered media: Scattering through natural porous formations (by far the most ubiquitous\nexample of disordered media) represents a formidable tool to identify effective\nflow and transport properties. In particular, we are interested here in the\nscattering of a passive scalar as determined by a steady velocity field which\nis generated by a line of singularity. The velocity undergoes to erratic\nspatial variations, and concurrently the evolution of the scattering is\nconveniently described within a stochastic framework that regards the\nconductivity of the hosting medium as a stationary, Gaussian, random field.\nUnlike the similar one for uniform (in the mean) flow-fields, the problem at\nstake results much more complex. Central for the present study is the\nfluctuation of the driving field, that is computed in closed (analytical) form\nas large time limit of the same quantity in the unsteady state flow regime. The\nstructure of the second-order moment X_{rr}, quantifying the scattering along\nthe radial direction, is explained by the rapid change of the distance along\nwhich the velocities of two fluid particles become uncorrelated. Moreover, two\napproximate, analytical expressions are shown to be quite accurate into\nreproducing the full simulations of X_{rr}. Finally, the same problem is\nencountered in other fields, belonging both to the classical and to the quantum\nphysics. As such, our results lend themselves to be used within a context much\nwider than that exploited in the present study.",
        "positive": "Mechanisms to Splay-Bend Nematic Phases: While twist-bend nematic phases have been extensively studied, the\nexperimental observation of two dimensional, oscillating splay-bend phases is\nrecent. We consider two theoretical models that have been used to explain the\nformation of twist-bend phases -- flexoelectricity and bond orientational order\n-- as mechanisms to induce splay-bend phases. Flexoelectricity is a viable\nmechanism, and splay and bend flexoelectric couplings can lead to splay-bend\nphases with different modulations. We show that while bond orientational order\ncircumvents the need for higher order terms in the free energy, the important\nrole of nematic symmetry and phase chirality rules it out as a basic mechanism."
    },
    {
        "anchor": "Mode-coupling approach for the slow dynamics of a liquid on a spherical\n  substrate: We study the dynamics of a one-component liquid constrained on a spherical\nsubstrate, a 2-sphere, and investigate how the mode-coupling theory (MCT) can\ndescribe the new features brought by the presence of curvature. To this end we\nhave derived the MCT equations in a spherical geometry. We find that, as seen\nfrom the MCT, the slow dynamics of liquids in curved space at low temperature\ndoes not qualitatively differ from that of glass-forming liquids in Euclidean\nspace. The MCT predicts the right trend for the evolution of the relaxation\nslowdown with curvature but is dramatically off at a quantitative level.",
        "positive": "Coupling model analysis of interchain coupled chain dynamics of PEO in\n  blends with PMMA: Quasielastic neutron scattering and molecular dynamics simulation data from\nPEO/PMMA blends found that for short times the self-dynamics of PEO chain\nfollows the Rouse model, but at longer times past tc=1 to 2 ns it becomes\nslower and departs from the Rouse model in dependences on time, momentum\ntransfer, and temperature. To explain the anomalies, others had proposed the\nrandom Rouse model (RRM) in which each monomer has different mobility taken\nfrom a broad log-normal distribution. Despite the success of the RRM, Diddens,\nBrodeck and Heuer [EPL, 95, 56003 (2011)] extracted the distribution of\nfriction coefficients from the MD simulations of a PEO/PMMA blend and found the\ndistribution is much narrower than expected from the RRM. We propose a simpler\nalternative explanation of the data by utilizing alone the observed crossover\nof PEO chain dynamics at tc. The present problem is just a special case of a\ngeneral property of relaxation in interacting systems, which is the crossover\nfrom independent relaxation to coupled many-body relaxation at some tc\ndetermined by the interaction potential. The generality is brought out vividly\nby pointing out that the crossover also had been observed by neutron scattering\nfrom entangled chains relaxation in monodisperse homo-polymers, and from the\nsegmental \\alpha-relaxation of PEO in blends with PMMA. The properties of all\nthe relaxation processes in connection with the crossover are similar, despite\nthe length-scales of the relaxation in these systems are widely different."
    },
    {
        "anchor": "Diffraction of light by topological defects in liquid crystals: We study light scattering by a hedgehog-like and linear disclination\ntopological defects in a nematic liquid crystal by a metric approach. Light\npropagating near such defects feels an effective metric equivalent to the\nspatial part of the global monopole and cosmic string geometries. We obtain the\nscattering amplitude and the differential and total scattering cross section\nfor the case of the hedgehog defect, in terms of the characteristic parameters\nof the liquid crystal. Studying the disclination case, a cylindrical partial\nwave method is developed. As an application of the previous developments, we\nalso examine the temperature influence on the localization of the diffraction\npatterns.",
        "positive": "Global phase diagrams of binary dipolar fluid mixtures: We apply a modified mean-field density functional theory to determine the\nphase behavior of binary mixtures of Stockmayer fluids whose spherical\nconstituents interact according to Lennard-Jones (LJ) pair potentials with\nembedded pointlike dipole moments. On the basis of systematic numerical\ncalculations we construct the global phase diagrams of these systems in the\nthree-dimensional thermodynamic space of temperature, pressure, and chemical\npotential difference of the two components. The vapor-liquid, isotropic liquid\n- isotropic liquid, isotropic liquid - ferromagnetic liquid, and ferromagnetic\nliquid - ferromagnetic liquid first-order phase separations are investigated.\nThe loci of the second-order isotropic fluid - ferromagnetic fluid transition\nare calculated from Landau theory. Liquid-vapor and liquid-liquid critical\nlines, tricritical lines, triple lines, and lines of critical end points of the\nbinary Stockmayer mixtures are also determined. We discuss how the topology of\nthe phase diagrams change upon varying the strengths of the two dipole moments\nof the two species as well as their sizes."
    },
    {
        "anchor": "The Effect of Pinning on Drag in Coupled One-Dimensional Channels of\n  Particles: We consider a simple model for examining the effects of quenched disorder on\ndrag consisting of particles interacting via a Yukawa potential that are placed\nin two coupled one-dimensional channels. The particles in one channel are\ndriven and experience a drag from the undriven particles in the second channel.\nIn the absence of pinning, for a finite driving force there is no pinned phase;\ninstead, there are two dynamical regimes of completely coupled or locked flow\nand partially coupled flow. When pinning is added to one or both channels, we\nfind that a remarkably rich variety of dynamical phases and drag effects arise\nthat can be clearly identified by features in the velocity force curves. The\npresence of quenched disorder in only the undriven channel can induce a pinned\nphase in both channels. Above the depinning transition, the drag on the driven\nparticles decreases with increasing pinning strength, and for high enough\npinning strength, the particles in the undriven channel reach a reentrant\npinned phase which produces a complete decoupling of the channels. We map out\nthe dynamic phase diagrams as a function of pinning strength and the density of\npinning in each channel. Our results may be relevant for understanding drag\ncoupling in 1D Wigner crystal phases, and the effects we observe could also be\nexplored using colloids in coupled channels produced with optical arrays,\nvortices in nanostructured superconductors, or other layered systems where drag\neffects arise.",
        "positive": "Dielectric mismatch effects on polyelectrolyte solutions in electrified\n  nanopores: Insights from mean-field theory: We utilize the self-consistent field theory to explore the mechanical and\nelectrical properties of charged surfaces immersed in polyelectrolyte solutions\nthat could be potentially useful for electrochemical applications. Our research\nfocuses on how the dielectric heterogeneity of the solution could affect the\ndisjoining pressure and differential capacitance of the electric double layer.\nRelying on the developed theoretical framework, based on the Noether's theorem,\nwe calculate the stress tensor, containing the term, arising from the\nconformational entropy of the polymer chains. With its help we compute the\ndisjoining pressure in polyelectrolyte solution confined between two parallel\ncharged surfaces and analyze its behavior as a function of separation between\nthe surfaces for different values of dielectric mismatch parameter. We also\ncalculate the differential capacitance of the electric double layer and discuss\nhow dielectric heterogeneity of the polyelectrolyte solution influences its\nvalues."
    },
    {
        "anchor": "Measurement theory of a density profile of small spheres on a\n  cylindrical surface: Conversion of force curve measured with surface force\n  apparatus into pressure on its surface element: Recently, in an ensemble of small spheres, we proposed a method that converts\nthe force between two large spheres into the pressure on the large sphere's\nsurface element. Using it, the density distribution of the small spheres around\nthe large sphere can be obtained experimentally. In a similar manner, in this\nletter, we propose a transform theory for surface force apparatus, which\ntransforms the force acting on the cylinder into the density distribution of\nthe small spheres on the cylindrical surface. The transform theory we derived\nis briefly explained in this letter.",
        "positive": "Quantitative modeling of laser speckle imaging: We have analyzed the image formation and dynamic properties in laser speckle\nimaging (LSI) both experimentally and with Monte-Carlo simulation. We show for\nthe case of a liquid inclusion that the spatial resolution and the signal\nitself are both significantly affected by scattering from the turbid\nenvironment. Multiple scattering leads to blurring of the dynamic inhomogeneity\nas detected by LSI. The presence of a non-fluctuating component of scattered\nlight results in the significant increase in the measured image contrast and\ncomplicates the estimation of the relaxation time. We present a refined\nprocessing scheme that allows a correct estimation of the relaxation time from\nLSI data."
    },
    {
        "anchor": "Driven polymer translocation through nanopores: slow versus fast\n  dynamics: We investigate the dynamics of polymer translocation through nanopores under\nexternal driving by 3D Langevin Dynamics simulations, focusing on the scaling\nof the average translocation time $\\tau$ versus the length of the polymer,\n$\\tau\\sim N^{\\alpha}$. For slow translocation, i.e., under low driving force\nand/or high friction, we find $\\alpha \\approx 1+\\nu \\approx 1.588$ where $\\nu$\ndenotes the Flory exponent. In contrast, $\\alpha\\approx 1.37$ is observed for\nfast translocation due to the highly deformed chain conformation on the trans\nside, reflecting a pronounced non-equilibrium situation. The dependence of the\ntranslocation time on the driving force is given by $\\tau \\sim F^{-1}$ and\n$\\tau \\sim F^{-0.80}$ for slow and fast translocation, respectively. These\nresults clarify the controversy on the magnitude of the scaling exponent\n$\\alpha$ for driven translocation.",
        "positive": "Mesophase formation in two-component cylindrical bottle-brush polymers: When two types of side chains (A,B) are densely grafted to a (stiff) backbone\nand the resulting bottle-brush polymer is in a solution under poor solvent\nconditions, an incompatibility between A and B leads to microphase separation\nin the resulting cylindrical brush. The possible types of ordering are\nreminiscent of the ordering of block copolymers in cylindrical confinement.\nStarting from this analogy, Leibler's theory of microphase separation in block\ncopolymer melts is generalized to derive a description of the system in the\nweak segregation limit. Also molecular dynamics simulation results of a\ncorresponding coarse-grained bead-spring model are presented. Using side chain\nlengths up to N = 50 effective monomers, the ratio of the Lennard-Jones energy\nparameter between unlike monomers $(\\epsilon_{AB})$ and monomers of the same\nkind $(\\epsilon _{AA} = \\epsilon_{BB})$ is varied. Various correlation\nfunctions are analyzed to study the conditions when (local) Janus cylinder-type\nordering and when (local) microphase separation in the direction along the\ncylinder axis occurs. Both the analytical theory and the simulations give\nevidence for short range order due to a tendency towards microphase separation\nin the axial direction, with a wavelength proportional to the side chain\ngyration radius, irrespective of temperature and grafting density, for a wide\nrange of these parameters."
    },
    {
        "anchor": "Diffusion of hard sphere fluids in disordered porous media: Enskog\n  theory description: We use the Enskog theory for the description of the self-diffusion\ncoefficient of hard sphere fluids in disordered porous media. Using the scaled\nparticle theory previously developed by us for the description of thermodynamic\nproperties of hard sphere fluids, simple analytical expressions for the contact\nvalues of the fluid-fluid and fluid-matrix pair distribution functions are\nobtained and used as the input of Enskog theory. The expressions obtained for\nthe contact values are described only by the geometric porosity and do not\ninclude the dependence on other types of porosity that are important for the\ndescription of thermodynamic properties. It is shown that the application of\nsuch contact values neglects the effects of trapping of fluid particles by a\nmatrix and at least the probe particle porosity $\\phi$ should be included in\nthe Enskog theory for a correct description of the matrix influence. In this\npaper we extend the Enskog theory by changing the contact values of the\nfluid-matrix and the fluid-fluid pair distribution functions with new\nproperties which include the dependence not only on geometric porosity but also\non probe particle porosity $\\phi$. It is shown that such semi-empirical\nimprovement of the Enskog theory corresponds to SPT2b1 approximation for the\ndescription of thermodynamic properties and it predicts correct trends for the\ninfluence of porous media on the diffusion coefficient of a hard sphere fluid\nin disordered porous media. Good agreement with computer simulations is\nillustrated. The effects of fluid density, fluid to matrix sphere size ratio,\nmatrix porosity and matrix morphology on the self-diffusion coefficient of hard\nsphere fluids are discussed.",
        "positive": "On the rheology of a liquid-vapor interface: The mass and momentum balances are theoretically studied in heterogeneous\ntwo-component systems. Following Gibbs the system is presented as two bulk and\na single surface phases. Comparing the equations derived with some typical\nrheological models, useful information about the location of the interface is\nobtained. It was demonstrated that the surface phase for insoluble surfactants\ncoincides with the equimolecular interface, while for soluble ones it is placed\non the surface of total mass density zero excess. In both cases the surface\nphase is close to the surface of tension and kinematic surface."
    },
    {
        "anchor": "Water diffusion in rough carbon nanotubes: We use molecular dynamics simulations to study the diffusion of water inside\ndeformed carbon nanotubes with different degrees of deformation at 300 K. We\nfound that the number of hydrogen bonds that water forms depends on nanotube\ntopology, leading to enhancement or suppression of water diffusion. The\nsimulation results reveal that more realistic nanotubes should be considered to\nunderstand the confined water diffusion behavior, at least for the narrowest\nnanotubes, when the interaction between water molecules and carbon atoms is\nrelevant.",
        "positive": "Droplet Size Distribution in Emulsions: The droplet size in emulsions is known to affect the rheological properties\nand plays a crucial role in the many applications of emulsions. Despite its\nimportance, the underlying mechanisms governing droplet size in emulsification\nremain poorly understood. We investigate the average drop size and size\ndistribution upon emulsification with a high-shear mixer for model oil-in-water\nemulsions stabilized by a surfactant. The size distribution is found to be a\nlog-normal distribution, resulting from the repetitive random breakup of drops.\nHigh-shear emulsification, the usual way of making emulsions, is therefore\nfound to be very different from turbulent emulsification given by the\nKolmogorov-Hinze theory for which power-law distributions of the drop size are\nexpected. In agreement with this, the mean droplet size does not follow a\nscaling with the Reynolds number of the emulsification flow, but rather a\ncapillary number scaling based on the viscosity of the continuous phase."
    },
    {
        "anchor": "Thermodynamical Scaling of the Glass Transition Dynamics: Classification of glass-forming liquids based on the dramatic change in their\nproperties upon approach to the glassy state is appealing, since this is the\nmost conspicuous and often-studied aspect of the glass transition. Herein, we\nshow that a generalized scaling, log tau proportional to T^(-1)V^(-gamma),\nwhere gamma is a material-constant, yields superpositioning for ten\nglass-formers, encompassing van der Waals molecules, associated liquids, and\npolymers. The exponent gamma reflects the degree to which volume, rather than\nthermal energy, governs the temperature and pressure dependence of the\nrelaxation times.",
        "positive": "Phase Separation and Emergent Structures in an Active Nematic: We consider a phenomenological continuum model for an active nematic fluid\nand show a universal, model independent, instability which renders the\nhomogeneous nematic state unstable to order fluctuations. Using numerical and\nanalytic tools we show that, for low energy excitations in the vicinity of a\ncritical point, this instability leads to a phase separation in which the\nordered regions form bands with the direction of nematic order being\nperpendicular to the direction of density gradient. We argue that this\nmechanism of phase separation, which we term self-regulation, is a universal\nfeature of active fluids."
    },
    {
        "anchor": "Conformation And Mechanical Response of Spray Deposited Single Strand\n  DNA on Gold: Single molecule force spectroscopy of DNA strands adsorbed at surfaces is a\npowerful technique used in air or liquid environments to quantify their\nmechanical properties. Although the force responses are limited to unfolding\nevents so far, single base detection might be possible in more drastic\ncleanliness conditions such as ultra high vacuum. Here, we report on high\nresolution imaging and pulling attempts at low temperature (5K) of a single\nstrand DNA (ssDNA) molecules composed of 20 cytosine bases adsorbed on Au(111)\nby scanning probe microscopy and numerical calculations. Using electrospray\ndeposition technique, the ssDNA were successfully transferred from solution\nonto a surface kept in ultra high vacuum. Real space characterizations reveal\nthat the ssDNA have an amorphous structure on gold in agreement with numerical\ncalculations. Subsequent substrate annealing promotes the desorption of solvent\nmolecules, DNA as individual molecules as well as the formation of DNA self\nassemblies. Furthermore, pulling experiments by force spectroscopy have been\nconducted to measure the mechanical response of the ssDNA while detaching. A\nperiodic pattern of 0.2 to 0.3nm is observed in the force curve which arises\nfrom the stick slip of single nucleotide bases over the gold. Although an intra\nmolecular response is obtained in the force curve, a clear distinction of each\nnucleotide detachment is not possible due the complex structure of ssDNA\nadsorbed on gold.",
        "positive": "Optimal control of colloidal trajectories in inertial microfluidics\n  using the Saffman effect: In inertial microfluidics colloidal particles in a Poiseuille flow experience\nthe Segr\\'e-Silberberg lift force, which drives them to specific positions in\nthe channel cross section. Due to the Saffman effect an external force applied\nalong the microchannel induces a cross-streamline migration to a new\nequilibrium position. We apply optimal control theory to design the time\nprotocol of the axial control force in order to steer a single particle as\nprecisely as possible from a channel inlet to an outlet at a chosen target\nposition. We discuss the influence of particle radius and channel length and\nshow that optimal steering is cheaper than using a constant control force.\nUsing a single optimized control-force protocol, we demonstrate that even a\npulse of particles spread along the channel axis can be steered to a target and\nthat particles of different radii can be separarted most efficiently."
    },
    {
        "anchor": "Dynamic coarse-graining fills the gap between atomistic simulations and\n  experimental investigations of mechanical unfolding: We present a dynamic coarse-graining technique that allows to simulate the\nmechanical unfolding of biomolecules or molecular complexes on experimentally\nrelevant time scales. It is based on Markov state models (MSM), which we\nconstruct from molecular dynamics simulations using the pulling coordinate as\nan order parameter. We obtain a sequence of MSMs as a function of the\ndiscretized pulling coordinate, and the pulling process is modeled by switching\namong the MSMs according to the protocol applied to unfold the complex. This\nway we cover seven orders of magnitude in pulling speed. In the region of rapid\npulling we additionally perform steered molecular dynamics simulations and find\nexcellent agreement between the results of the fully atomistic and the\ndynamically coarse-grained simulations. Our technique allows the determination\nof the rates of mechanical unfolding in a dynamical range from approximately\n$10^{-8}$/ns to $1$/ns thus reaching experimentally accessible time regimes\nwithout abandoning atomistic resolution.",
        "positive": "Polymer Informatics Beyond Homopolymers: Polymers are diverse and versatile materials that have met a wide range of\nmaterial application demands. They come in several flavors and architectures,\ne.g., homopolymers, copolymers, polymer blends, and polymers with additives.\nSearching this enormous space for suitable materials with a specific set of\nproperty/performance targets is thus non-trivial, painstaking, and expensive.\nSuch a search process can be made effective by the creation of rapid and\naccurate property predictors. In this work, we present a machine-learning\nframework to predict the thermal properties of homopolymers, copolymers, and\npolymer blends. A universal fingerprinting scheme capable of handling this\nentire polymer chemical class has been developed and a multi-task deep learning\nalgorithm is trained simultaneously on a large dataset of glass transition,\nmelting, and degradation temperatures. The developed models are accurate, fast,\nflexible, and scalable to other properties when suitable data become available."
    },
    {
        "anchor": "The Poisson Boltzmann equation and the charge separation phenomenon at\n  the silica-water interface: A holistic approach: The Poisson Boltzmann equation is known for its success in describing the\nDebye layer that arises from the charge separation phenomenon at the\nsilica/water interface. However, by treating only the mobile ionic charges in\nthe liquid, the Poisson Boltzmann equation accounts for only half of the\nelectrical double layer, with the other half, the surface charge layer, being\nbeyond its computational domain. In this work, we take a holistic approach to\nthe charge separation phenomenon at the silica/water interface by treating,\nwithin a single computational domain, the electrical double layer that\ncomprises both the mobile ions in the liquid and the surface charge density.\nThe Poisson Nernst Planck equations are used as the rigorous basis for our\nmethodology. The holistic approach has the advantage of being able to predict\nsurface charge variations that arise either from the addition of salt and acid\nto the liquid, or from the decrease of the liquid channel width to below twice\nthe Debye length. As the electrical double layer must be overall neutral, we\nuse this constraint to derive both the form of the static limit of the Poisson\nNernst Planck equations, as well as a global chemical potential that replaces\nthe classical zeta potential as the boundary value for the PB equation, which\ncan be re-derived from our formalism. We present several predictions of our\ntheory that are beyond the framework of the PB equation alone, e.g., the\nsurface capacitance and the so-called pK and pL values, the isoelectronic point\nat which the surface charge layer is neutralized, and the appearance of a\nDonnan potential that arises from the formation of an electrical double layer\nat the inlet regions of a nano-channel connected to the bulk reservoir. All\ntheory predictions are shown to be in good agreement with the experimental\nobservations.",
        "positive": "The origin of the strain-rate discontinuity in 2D foam rheometry with\n  circular geometry: The observed discontinuity in strain-rate for a two-dimensional foam\nundergoing shear in a (circular) Couette system is explained in terms of the\ncontinuum (Herschel-Bulkley) model. It is attributed to the finite difference\nbetween yield and limit stress."
    },
    {
        "anchor": "Polyelectrolyte-colloid complexes: polarizability and effective\n  interaction: We theoretically study the polarizability and the interactions of neutral\ncomplexes consisting of a semi-flexible polyelectrolyte adsorbed onto an\noppositely charged spherical colloid. In the systems we studied, the bending\nenergy of the chain is small compared to the Coulomb energy and the chains are\nalways adsorbed on the colloid. We observe that the polarizability is large for\nshort chains and small electrical fields and shows a non-monotonic behavior\nwith the chain length at fixed charge density. The polarizability has a maximum\nfor a chain length equal to half of the circumference of the colloid. For long\nchains we recover the polarizability of a classical conducting sphere. For\nshort chains, the existence of a permanent dipole moment of the complexes leads\nto a van der Waal's-type long-range attraction between them. This attractive\ninteraction vanishes for long chains (i.e., larger than the colloidal size),\nwhere the permanent dipole moment is negligible. For short distances the\ncomplexes interact with a deep short-ranged attraction which is due to\nenergetic bridging for short chains and entropic bridging for long chains.\nExceeding a critical chain length eventually leads to a pure repulsion. This\nshows that the stabilization of colloidal suspensions by polyelectrolyte\nadsorption is strongly dependent on the chain size relative to the colloidal\nsize: for long chains the suspensions are always stable (only repulsive forces\nbetween the particles), while for mid-sized and short chains there is\nattraction between the complexes and a salting-out can occur.",
        "positive": "Wet and dry internal friction can be measured with the Jarzynski\n  equality: The existence of two types of internal friction wet and dry is revisited, and\na simple protocol is proposed for distinguishing between the two types and\nextracting the appropriate internal friction coefficient. The scheme requires\nrepeatedly stretching a polymer molecule, and measuring the average work\ndissipated in the process by applying the Jarzynski equality. The internal\nfriction coefficient is then estimated from the average dissipated work in the\nextrapolated limit of zero solvent viscosity. The validity of the protocol is\nestablished through analytical calculations on a one-dimensional free-draining\nHookean spring-dashpot model for a polymer, and Brownian dynamics simulations\nof: (a) a single-mode nonlinear spring-dashpot model for a polymer, and (b) a\nfinitely extensible bead-spring chain with cohesive intra-chain interactions,\nboth of which incorporate fluctuating hydrodynamic interactions.\nWell-established single-molecule manipulation techniques, such as optical\ntweezer-based pulling, can be used to implement the suggested protocol\nexperimentally."
    },
    {
        "anchor": "Dissipative dynamics of a vortex state in a trapped Bose-condensed gas: We discuss dissipative dynamics of a vortex state in a trapped Bose-condensed\ngas at finite temperature and draw a scenario of decay of this state in a\nstatic trap. The interaction of the vortex with the thermal cloud transfers\nenergy from the vortex to the cloud and induces the motion of the vortex core\nto the border of the condensate. Once the vortex reaches the border, it\nimmediately decays through the creation of excitations. We calculate the\ncharacteristic life-time of a vortex state and address the question of how the\ndissipative dynamics of vortices can be studied experimentally.",
        "positive": "Supercooled Liquid Dynamics Studied via Shear-Mechanical Spectroscopy: We report dynamical shear-modulus measurements for five glass-forming liquids\n(pentaphenyl trimethyl trisiloxane, diethyl phthalate, dibutyl phthalate,\n1,2-propanediol, and m-touluidine). The shear-mechanical spectra are obtained\nby the piezoelectric shear-modulus gauge (PSG) method. This technique allows\none to measure the shear modulus ($10^{5} -10^{10}$ Pa) of the liquid within a\nfrequency range from 1 mHz to 10 kHz. We analyze the frequency-dependent\nresponse functions to investigate whether time-temperature superposition (TTS)\nis obeyed. We also study the shear-modulus loss-peak position and its\nhigh-frequency part. It has been suggested that when TTS applies, the\nhigh-frequency side of the imaginary part of the dielectric response decreases\nlike a power law of the frequency with an exponent -1/2. This conjecture is\nanalyzed on the basis of the shear mechanical data. We find that TTS is obeyed\nfor pentaphenyl trimethyl trisiloxane and in 1,2-propanediol while in the\nremaining liquids evidence of a mechanical $\\beta$ process is found. Although\nthe the high-frequency power law behavior $\\omega^{-\\alpha}$ of the shear-loss\nmay approach a limiting value of $\\alpha=0.5$ when lowering the temperature, we\nfind that the exponent lies systematically above this value (around 0.4). For\nthe two liquids without beta relaxation (pentaphenyl trimethyl trisiloxane and\n1,2-propanediol) we also test the shoving model prediction, according to which\nthe the relaxation-time activation energy is proportional to the instantaneous\nshear modulus. We find that the data are well described by this model."
    },
    {
        "anchor": "Numerical determination of shear stress relaxation modulus of polymer\n  glasses: Focusing on simulated polymer glasses well below the glass transition, we\nconfirm the validity and the efficiency of the recently proposed simple-average\nexpression $G(t) = \\mu_A - h(t)$ for the computational determination of the\nshear stress relaxation modulus $G(t)$. Here, $\\mu_A = G(0)$ characterizes the\naffine shear transformation of the system at $t=0$ and $h(t)$ the mean-square\ndisplacement of the instantaneous shear stress as a function of time $t$. This\nrelation is seen to be particulary useful for systems with quenched or sluggish\ntransient shear stresses which necessarily arise below the glass transition.\nThe commonly accepted relation $G(t)=c(t)$ using the shear stress\nauto-correlation function $c(t)$ becomes incorrect in this limit.",
        "positive": "Domain walls in two-dimensional nematics confined in a small circular\n  cavity: Using Monte Carlo simulation, we study a fluid of two-dimensional hard rods\ninside a small circular cavity bounded by a hard wall, from the dilute regime\nto the high-density, layering regime. Both planar and homeotropic anchoring of\nthe nematic director can be induced at the walls through a free-energy penalty.\nThe circular geometry creates frustration in the nematic phase and a\npolar-symmetry configuration with a distorted director field plus two $+1/2$\ndisclinations is created. At higher densities, a quasi-uniform structure is\nobserved with a (minimal) director distortion which is relaxed via the\nformation of orientational domain walls. This novel structure is not predicted\nby elasticity theory and is similar to the step-like structures observed in\nthree-dimensional hybrid slit pores. We speculate that the formation of domain\nwalls is a general mechanism to relax elastic stresses in conditions of strong\nsurface anchoring and severe spatial confinement."
    },
    {
        "anchor": "Vibrated polar disks: spontaneous motion, binary collisions, and\n  collective dynamics: We study the spontaneous motion, binary collisions, and collective dynamics\nof \"polar disks\", i.e. purpose-built particles which, when vibrated between two\nhorizontal plates, move coherently along a direction strongly correlated to\ntheir intrinsic polarity. The motion of our particles, although nominally\nthree-dimensional and complicated, is well accounted for by a two-dimensional\npersistent random walk. Their binary collisions are spatiotemporally extended\nevents during which multiple actual collisions happen, yielding a weak average\neffective alignment. We show that this well-controlled, \"dry active matter\"\nsystem can display collective motion with orientationally-ordered regions of\nthe order of the system size. We provide evidence of strong number density in\nthe most ordered regimes observed. These results are discussed in the light of\nthe limitations of our system, notably those due to the inevitable presence of\nwalls.",
        "positive": "Phase separation dynamics of polydisperse colloids: a mean-field\n  lattice-gas theory: New insights into phase separation in colloidal suspensions are provided via\na new dynamical theory based on the Polydisperse Lattice-Gas model. The model\ngives a simplified description of polydisperse colloids, incorporating a\nhard-core repulsion combined with polydispersity in the strength of the\nattraction between neighbouring particles. Our mean-field equations describe\nthe local concentration evolution for each of an arbitrary number of species,\nand for an arbitrary overall composition of the system. We focus on the\npredictions for the dynamics of colloidal gas-liquid phase separation after a\nquench into the coexistence region. The critical point and the relevant\nspinodal curves are determined analytically, with the latter depending only on\nthree moments of the overall composition. The results for the early-time\nspinodal dynamics show qualitative changes as one crosses a 'quenched' spinodal\nthat excludes fractionation and so allows only density fluctuations at fixed\ncomposition. This effect occurs for dense systems, in agreement with a\nconjecture by Warren that, at high density, fractionation should be generically\nslow because it requires inter-diffusion of particles. We verify this\nconclusion by showing that the observed qualitative changes disappear when\ndirect particle-particle swaps are allowed in the dynamics. Finally, the rich\nbehaviour beyond the spinodal regime is examined, where we find that the\nevaporation of gas bubbles with strongly fractionated interfaces causes\nlong-lived composition heterogeneities in the liquid phase; we introduce a\ntwo-dimensional density histogram method that allows such effects to be easily\nvisualized for an arbitrary number of particle species."
    },
    {
        "anchor": "Geometric percolation of hard nanorods: the interplay of spontaneous and\n  externally induced uniaxial particle alignment: We present a numerical study on geometric percolation in liquid dispersions\nof hard slender colloidal particles subjected to an external orienting field.\nIn the formulation and liquid-state processing of nanocomposite materials, the\nalignment of particles by external fields such as electric, magnetic or flow\nfields is practically inevitable, and often works against the emergence of\nlarge nanoparticle networks. Using continuum percolation theory in conjunction\nwith Onsager theory, we investigate how the interplay between externally\ninduced alignment and the spontaneous symmetry breaking of the uniaxial nematic\nphase affects cluster formation within nanoparticle dispersions. It is known\nthat the enhancement of particle alignment by means of a density increase or an\nexternal field may result in the breakdown of an already percolating network.\nAs a result, percolation can be limited to a small region of the phase diagram\nonly. Here, we demonstrate that the existence and shape of such a \"percolation\nisland\" in the phase diagram crucially depends on the connectivity length -- a\ncritical distance defining direct connections between neighbouring particles.\nDeformations of this percolation island can lead to peculiar re-entrance\neffects, in which a system-spanning network forms and breaks down multiple\ntimes with increasing particle density.",
        "positive": "Effect of the vibration profile on shallow granular systems: We describe the collective behavior of a system of many inelastic spherical\nparticles inside a box which is being periodically vibrated. The box is\nshallow, with large horizontal dimensions, while the height is less than two\nparticle diameters. The vibrations are not symmetric: the time the box is\nmoving up is, in general, different to the time it is moving down. The limit\ncycles of isolated grains are largely affected by the asymmetry of the\nvibration mode, increasing the size in phase space of the chaotic regions. When\nmany grains are placed in the box, the phase separation between dense,\nsolid-like regions, coexisting with fluid-like regions takes place at smaller\nglobal densities for asymmetric vibration profiles. Besides, the order\nparameter of the transition takes larger values when asymmetric forcing is\nused."
    },
    {
        "anchor": "Integral equations for simple fluids in a general reference functional\n  approach: The integral equations for the correlation functions of an inhomogeneous\nfluid mixture are derived using a functional Taylor expansion of the free\nenergy around an inhomogeneous equilibrium distribution. The system of\nequations is closed by the introduction of a reference functional for the\ncorrelations beyond second order in the density difference from the equilibrium\ndistribution. Explicit expressions are obtained for energies required to insert\nparticles of the fluid mixture into the inhomogeneous system. The approach is\nillustrated by the determination of the equation of state of a simple,\ntruncated Lennard--Jones fluid and the analysis of the behavior of this fluid\nnear a hard wall. The wall--fluid integral equation exhibits complete drying\nand the corresponding coexisting densities are in good agreement with those\nobtained from the standard (Maxwell) construction applied to the bulk fluid.\nSelf--consistency of the approach is examined by analyzing the\nvirial/compressibility routes to the equation of state and the Gibbs--Duhem\nrelation for the bulk fluid, and the contact density sum rule and the Gibbs\nadsorption equation for the hard wall problem. For the bulk fluid, we find good\nself--consistency for stable states outside the critical region. For the hard\nwall problem, the Gibbs adsorption equation is fulfilled very well near phase\ncoexistence where the adsorption is large.For the contact density sum rule, we\nfind some deviationsnear coexistence due to a slight disagreement between the\ncoexisting density for the gas phase obtained from the Maxwell construction and\nfrom complete drying at the hard wall.",
        "positive": "Simulation of Claylike Colloids: We investigate properties of dense suspensions and sediments of small\nspherical silt particles by means of a combined Molecular Dynamics (MD) and\nStochastic Rotation Dynamics (SRD) simulation. We include van der Waals and\neffective electrostatic interactions between the colloidal particles, as well\nas Brownian motion and hydrodynamic interactions which are calculated in the\nSRD-part. We present the simulation technique and first results. We have\nmeasured velocity distributions, diffusion coefficients, sedimentation\nvelocity, spatial correlation functions and we have explored the phase diagram\ndepending on the parameters of the potentials and on the volume fraction."
    },
    {
        "anchor": "Normal state of highly polarized Fermi gases: Full many-body treatment: We consider a single \\down atom within a Fermi sea of \\up atoms. We elucidate\nby a full many-body analysis the quite mysterious agreement between Monte-Carlo\nresults and approximate calculations taking only into account single\nparticle-hole excitations. It results from a nearly perfect destructive\ninterference of the contributions of states with more than one particle-hole\npair. This is linked to the remarkable efficiency of the expansion in powers of\nhole wavevectors, the lowest order leading to perfect interference. Going up to\ntwo particle-hole pairs gives an essentially perfect agreement with known exact\nresults. Hence our treatment amounts to an exact solution of this problem.",
        "positive": "Sequential Monte Carlo Methods for Protein Folding: We describe a class of growth algorithms for finding low energy states of\nheteropolymers. These polymers form toy models for proteins, and the hope is\nthat similar methods will ultimately be useful for finding native states of\nreal proteins from heuristic or a priori determined force fields. These\nalgorithms share with standard Markov chain Monte Carlo methods that they\ngenerate Gibbs-Boltzmann distributions, but they are not based on the strategy\nthat this distribution is obtained as stationary state of a suitably\nconstructed Markov chain. Rather, they are based on growing the polymer by\nsuccessively adding individual particles, guiding the growth towards\nconfigurations with lower energies, and using \"population control\" to eliminate\nbad configurations and increase the number of \"good ones\". This is not done via\na breadth-first implementation as in genetic algorithms, but depth-first via\nrecursive backtracking. As seen from various benchmark tests, the resulting\nalgorithms are extremely efficient for lattice models, and are still\ncompetitive with other methods for simple off-lattice models."
    },
    {
        "anchor": "Dynamics and stability of a compound particle -- a theoretical study: Particles confined in droplets are called compound particles. They are\nencountered in various biological and soft matter systems. Hydrodynamics can\nplay a decisive role in determining the configuration and stability of these\nmultiphase structures during their preparation and use. Therefore, we\ninvestigate the dynamics and stability of a concentric compound particle under\nexternal forces and imposed flows. Governing equations are solved analytically\nin the inertia-less limit using the standard technique of superposition of\nvector harmonics and the solutions obtained are reported in terms of steady\nstate flow fields, viscous drag on the particle and the time evolution of the\nconfining drop shape. The limiting form of compound particle as a thin film\ncoated rigid particle is analyzed in each case. We find that concentric\nconfiguration of a rotating compound particle is a steady state solution, and\nwe calculate the extra force required to stabilize the concentric configuration\nof a translating compound particle. A comprehensive comparison of drop\ndeformations in various linear ambient flows is also provided. Based on the\nfindings, we propose pulsatile flow as a reliable method to transport compound\nparticles without breakup of the confining drop. Thus, our analysis provides\nuseful guidelines in preparation and transportation of stable compound\nparticles in the context of nucleated cells, aerosols, droplet-based\nencapsulation of motile organisms and polymer microcapsules.",
        "positive": "Swelling of two-dimensional polymer rings by trapped particles: The mean area of a two-dimensional Gaussian ring of $N$ monomers is known to\ndiverge when the ring is subject to a critical pressure differential, $p_c \\sim\nN^{-1}$. In a recent publication [Eur. Phys. J. E 19, 461 (2006)] we have shown\nthat for an inextensible freely jointed ring this divergence turns into a\nsecond-order transition from a crumpled state, where the mean area scales as\n$<A> \\sim N$, to a smooth state with $<A> \\sim N^2$. In the current work we\nextend these two models to the case where the swelling of the ring is caused by\ntrapped ideal-gas particles. The Gaussian model is solved exactly, and the\nfreely jointed one is treated using a Flory argument, mean-field theory, and\nMonte Carlo simulations. For fixed number $Q$ of trapped particles the\ncriticality disappears in both models through an unusual mechanism, arising\nfrom the absence of an area constraint. In the Gaussian case the ring swells to\nsuch a mean area, $<A> \\sim NQ$, that the pressure exerted by the particles is\nat $p_c$ for any $Q$. In the freely jointed model the mean area is such that\nthe particle pressure is always higher than $p_c$, and $<A>$ consequently\nfollows a single scaling law, $<A> \\sim N^2 f(Q/N)$, for any $Q$. By contrast,\nwhen the particles are in contact with a reservoir of fixed chemical potential,\nthe criticality is retained. Thus, the two ensembles are manifestly\ninequivalent in these systems."
    },
    {
        "anchor": "Study on the fragmentation of shells: Fragmentation can be observed in nature and in everyday life on a wide range\nof length scales and for all kinds of technical applications. Most studies on\ndynamic failure focus on the behaviour of bulk systems in one, two and three\ndimensions under impact and explosive loading, showing universal power law\nbehaviour of fragment size distribution. However, hardly any studies have been\ndevoted to fragmentation of shells. We present a detailed experimental and\ntheoretical study on the fragmentation of closed thin shells of various\nmaterials, due to an excess load inside the system and impact with a hard wall.\nCharacteristic fragmentation mechanisms are identified by means of a high speed\ncamera and fragment shapes and mass distributions are evaluated. Theoretical\nrationalisation is given by means of stochastic break-up models and large-scale\ndiscrete element simulations with spherical shell systems under different\nextreme loading situations. By this we ex-plain fragment shapes and\ndistributions and prove a power law for the fragment mass distribution.\nSatisfactory agreement between experimental findings and nu-merical predictions\nof the exponents of the power laws for the fragment shapes is obtained.",
        "positive": "Root mean squares of distance and geodesic between two constituent\n  particles within fractal aggregates prepared by BCCA, DLA, and GSAW\n  procedures: Understanding the geodesic properties of fractal aggregates is essential, as\ntheir thermal and mechanical properties are characterized by their geodesics.\nIn this study, we investigate the root mean square (RMS) of the geodesic\nbetween two constituent particles within fractal aggregates prepared by\nballistic cluster-cluster aggregation (BCCA), diffusion-limited aggregation\n(DLA), and growing self-avoiding walk (GSAW) processes in two- and\nthree-dimensional spaces. We find that the dependence of the RMS of the\ngeodesic on the number of constituent particles is given by the following\nequation: $N \\approx k_{\\rm g} {D_{\\rm RMS}}^{d_{\\rm g}}$, where $N$ is the\nnumber of constituent particles and $D_{\\rm RMS}$ is the RMS of the geodesic.\nWe numerically obtain the prefactor $k_{\\rm g}$ and exponent $d_{\\rm g}$ for\nthese fractal aggregates. We name the exponent ``the geodesic dimension'', and\nit is compared with the fractal dimension. Our findings show that the\ndifference between fractal and geodesic dimensions varies significantly\ndepending on the preparation procedure for fractals."
    },
    {
        "anchor": "Approach to Hyperuniformity in a Metallic Glass-Forming Material\n  Exhibiting a Fragile to Strong Glass Transition: We investigate a metallic glass-forming (GF) material (Al90Sm10) exhibiting a\nfragile-strong (FS) glass-formation by molecular dynamics simulation to better\nunderstand this highly distinctive pattern of glass-formation in which many of\nthe usual phenomenological relations describing relaxation times and diffusion\nof OGF liquids no longer apply, and where instead genuine thermodynamic\nfeatures are observed in response functions and little thermodynamic signature\nis exhibited at the glass transition temperature, Tg. Given the many unexpected\nsimilarities between the thermodynamics and dynamics of this metallic GF\nmaterial with water, we first focus on the anomalous static scattering in this\nliquid, following recent studies on water, silicon and other FS GF liquids. In\nparticular, we quantify the 'hyperuniformity index' H of our liquid which\nprovides a quantitative measure of molecular 'jamming'. To gain insight into\nthe T-dependence and magnitude of H, we also estimated another more familiar\nmeasure of particle localization, the Debye-Waller parameter $<u^2>$ describing\nthe mean-square particle displacement on a timescale on the order of the fast\nrelaxation time, and we also calculate H and $<u^2>$ for heated crystalline Cu.\nThis comparative analysis between H and $<u^2>$ for crystalline and metallic\nglass materials allows us to understand the critical value of H on the order of\n$10^{-3}$ as being analogous to the Lindemann criterion for both the melting of\ncrystals and the 'softening' of glasses. We further interpret the emergence of\nFS GF and liquid-liquid phase separation in this class of liquids to arise from\na cooperative assembly process in the GF liquid.",
        "positive": "Counterion-mediated Electrostatic Interactions between Helical Molecules: We study the interaction of two cylinders with helical charge distribution\nmediated by neutralizing counterions, by analyzing the separation as well as\nthe azimuthal angle dependence of the interaction force in the weak and strong\ncoupling limit. While the azimuthal dependence of the interaction in the weak\ncoupling limit is overall small and mostly negligible, the strong coupling\nlimit leads to qualitatively new features of the interaction, among others also\nto an orientationally dependent optimal configuration that is driven by angular\ndependence of the correlation attraction. We investigate the properties of this\nazimuthal ordering in detail and compare it to existing results."
    },
    {
        "anchor": "Mixtures of Charged Colloid and Neutral Polymer: Influence of\n  Electrostatic Interactions on Demixing and Interfacial Tension: The equilibrium phase behavior of a binary mixture of charged colloids and\nneutral, non-adsorbing polymers is studied within free-volume theory. A model\nmixture of charged hard-sphere macroions and ideal, coarse-grained,\neffective-sphere polymers is mapped first onto a binary hard-sphere mixture\nwith non-additive diameters and then onto an effective Asakura-Oosawa model [S.\nAsakura and F. Oosawa, J. Chem. Phys. 22, 1255 (1954)]. The effective model is\ndefined by a single dimensionless parameter -- the ratio of the polymer\ndiameter to the effective colloid diameter. For high salt-to-counterion\nconcentration ratios, a free-volume approximation for the free energy is used\nto compute the fluid phase diagram, which describes demixing into colloid-rich\n(liquid) and colloid-poor (vapor) phases. Increasing the range of electrostatic\ninteractions shifts the demixing binodal toward higher polymer concentration,\nstabilizing the mixture. The enhanced stability is attributed to a weakening of\npolymer depletion-induced attraction between electrostatically repelling\nmacroions. Comparison with predictions of density-functional theory reveals a\ncorresponding increase in the liquid-vapor interfacial tension. The predicted\ntrends in phase stability are consistent with observed behavior of\nprotein-polysaccharide mixtures in food colloids.",
        "positive": "Microfluidic In Situ Measurement of Poisson's Ratio of Hydrogels: Being able to precisely characterize the mechanical properties of soft\nmicroparticles is essential for numerous situations from the understanding of\nthe flow of biological fluids to the development of soft micro-robots. Here we\npresent a simple measurement technique for the Poisson's ratio of soft\nmicron-sized hydrogels in the presence of a surrounding liquid. This methods\nrelies on the measurement of the deformation in two orthogonal directions of a\nrectangular hydrogel slab compressed uni-axially inside a microfluidic channel.\nDue to the in situ character of the method, the sample does not need to be\ndried, allowing for the measurement of the mechanical properties of swollen\nhydrogels. Using this method we determine the Poisson's ratio of hydrogel\nparticles composed of polyethylene glycol (PEG) and varying solvents fabricated\nusing a lithography technique. The results demonstrate with high precision the\ndependence of the hydrogel compressibility on the solvent fraction and\ncharacter. The method, easy to implement, can be adapted for the measurement of\na variety of soft and biological materials."
    },
    {
        "anchor": "Flow transitions in two-dimensional foams: For sufficiently slow rates of strain, flowing foam can exhibit inhomogeneous\nflows. The nature of these flows is an area of active study in both\ntwo-dimensional model foams and three dimensional foam. Recent work in\nthree-dimensional foam has identified three distinct regimes of flow [S. Rodts,\nJ. C. Baudez, and P. Coussot, Europhys. Lett. {\\bf 69}, 636 (2005)]. Two of\nthese regimes are identified with continuum behavior (full flow and\nshear-banding), and the third regime is identified as a discrete regime\nexhibiting extreme localization. In this paper, the discrete regime is studied\nin more detail using a model two dimensional foam: a bubble raft. We\ncharacterize the behavior of the bubble raft subjected to a constant rate of\nstrain as a function of time, system size, and applied rate of strain. We\nobserve localized flow that is consistent with the coexistence of a power-law\nfluid with rigid body rotation. As a function of applied rate of strain, there\nis a transition from a continuum description of the flow to discrete flow when\nthe thickness of the flow region is approximately 10 bubbles. This occurs at an\napplied rotation rate of approximately $0.07 {\\rm s^{-1}}$.",
        "positive": "Liquid-crystal-based topological photonics: Topological photonics harnesses the physics of topological insulators to\ncontrol the behavior of light. Photonic modes robust against material\nimperfections are an example of such control. In this work, we propose a\nsoft-matter platform based on nematic liquid crystals that supports photonic\ntopological insulators. The orientation of liquid crystal molecules introduces\nan extra geometric degree of freedom which in conjunction with suitably\ndesigned structural properties, leads to the creation of topologically\nprotected states of light. The use of soft building blocks potentially allows\nfor reconfigurable systems that exploit the interplay between light and the\nsoft responsive medium."
    },
    {
        "anchor": "Force chain structure in a rod-withdrawn granular layer: When a rod is vertically withdrawn from a granular layer, oblique force\nchains can be developed by effective shearing. In this study, the force-chain\nstructure in a rod-withdrawn granular layer was experimentally investigated\nusing a photoelastic technique. The rod is vertically withdrawn from a\ntwo-dimensional granular layer consisting of bidisperse photoelastic disks.\nDuring the withdrawal, the development process of force chains is visualized by\nthe photoelastic effect. By systematic analysis of photoelastic images, force\nchain structures newly developed by the rod withdrawing are identified and\nanalyzed. In particular, the relation between the rod-withdrawing force\n$F_\\mathrm{w}$, total force-chains force $F_\\mathrm{t}$, and their average\norientation $\\theta$ are discussed. We find that the oblique force chains are\nnewly developed by withdrawing. The force-chain angle $\\theta$ is almost\nconstant (approximately $20^{\\circ}$ from the horizontal), and the total force\n$F_\\mathrm{t}$ gradually increases by the withdrawal. In addition,\n$F_\\mathrm{t}\\sin\\theta$ shows a clear correlation with $F_\\mathrm{w}$.",
        "positive": "Crowding effect on helix-coil transition: beyond entropic stabilization: We report circular dichroism measurements on the helix-coil transition of\npoly(L-glutamic acid) in solution with polyethylene glycol (PEG) as a crowding\nagent. Using small angle neutron scattering, PEG solutions have been\ncharacterized and found to be well described by the picture of a transient\nnetwork of mesh size $\\xi$, usual for semi-diluted chains in good solvent. We\nshow that the increase of PEG concentration stabilizes the helices and\nincreases the transition temperature. But more unexpectedly we also notice that\nthe increase of crowding agent concentration reduces the mean helix extent at\nthe transition, or in other words reduces its cooperative feature. This result\ncannot be accounted for by an entropic stabilization mechanism. Comparing the\nmean length of helices at the transition and the mesh size of the PEG network,\nour results strongly suggest two regimes: helices shorter or longer than the\nmesh size."
    },
    {
        "anchor": "Hopper flows of deformable particles: Numerous experimental and computational studies show that continuous hopper\nflows of granular materials obey the Beverloo equation that relates the volume\nflow rate $Q$ and the orifice width $w$: $Q \\sim (w/\\sigma_{\\rm\navg}-k)^{\\beta}$, where $\\sigma_{\\rm avg}$ is the average particle diameter,\n$k\\sigma_{\\rm avg}$ is an offset where $Q\\sim 0$, the power-law scaling\nexponent $\\beta=d-1/2$, and $d$ is the spatial dimension. Recent studies of\nhopper flows of deformable particles in different background fluids suggest\nthat the particle stiffness and dissipation mechanism can also strongly affect\nthe power-law scaling exponent $\\beta$. We carry out computational studies of\nhopper flows of deformable particles with both kinetic friction and background\nfluid dissipation in two and three dimensions. We show that the exponent\n$\\beta$ varies continuously with the ratio of the viscous drag to the kinetic\nfriction coefficient, $\\lambda=\\zeta/\\mu$. $\\beta = d-1/2$ in the $\\lambda\n\\rightarrow 0$ limit and $d-3/2$ in the $\\lambda \\rightarrow \\infty$ limit,\nwith a midpoint $\\lambda_c$ that depends on the hopper opening angle\n$\\theta_w$. We also characterize the spatial structure of the flows and\nassociate changes in spatial structure of the hopper flows to changes in the\nexponent $\\beta$. The offset $k$ increases with particle stiffness until $k\n\\sim k_{\\rm max}$ in the hard-particle limit, where $k_{\\rm max} \\sim 3.5$ is\nlarger for $\\lambda \\rightarrow \\infty$ compared to that for $\\lambda\n\\rightarrow 0$. Finally, we show that the simulations of hopper flows of\ndeformable particles in the $\\lambda \\rightarrow \\infty$ limit recapitulate the\nexperimental results for quasi-2D hopper flows of oil droplets in water.",
        "positive": "Unraveling the Salvinia paradox: design principles for submerged\n  superhydrophobicity: The complex structure of the Salvinia molesta is investigated via rare event\nmolecular dynamics simulations. Results show that a hydrophilic/hydrophobic\npatterning together with a re-entrant geometry control the free energy barriers\nfor bubble nucleation and for the Cassie-Wenzel transition. This natural\nparadigm is translated into simple macroscopic design criteria for engineering\nrobust superhydrophobicity in submerged applications."
    },
    {
        "anchor": "Translational and rotational temperatures of a 2D vibrated granular gas\n  in microgravity: We present an experimental study performed on a vibrated granular gas\nenclosed into a 2D rectangular cell. Experiments are realized in microgravity.\nHigh speed video recording and optical tracking allow to obtain the full\nkinematics (translation and rotation) of the particles. The inelastic\nparameters are retrieved from the experimental trajectories as well as the\ntranslational and rotational velocity distributions. We report that the\nexperimental ratio of translational versus rotational temperature decreases to\nthe density of the medium but increases with the driving velocity of the cell.\nThese experimental results are compared with existing theories and we point out\nthe differences observed. We also present a model which fairly predicts the\nequilibrium experimental temperatures along the direction of vibration.",
        "positive": "Impact of roughness on the instability of a free-cooling granular gas: A linear stability analysis of the hydrodynamic equations with respect to the\nhomogeneous cooling state is carried out to identify the conditions for\nstability of a granular gas of rough hard spheres. The description is based on\nthe results for the transport coefficients derived from the Boltzmann equation\nfor inelastic rough hard spheres [Phys. Rev. E 90, 022205 (2014)], which take\ninto account the complete nonlinear dependence of the transport coefficients\nand the cooling rate on the coefficients of normal and tangential restitution.\nAs expected, linear stability analysis shows that a doubly degenerate\ntransversal (shear) mode and a longitudinal (\"heat\") mode are unstable with\nrespect to long enough wavelength excitations. The instability is driven by the\nshear mode above a certain inelasticity threshold; at larger inelasticity,\nhowever, the instability is driven by the heat mode for an\ninelasticity-dependent range of medium roughness. Comparison with the case of a\ngranular gas of inelastic smooth spheres confirms previous simulation results\nabout the dual role played by surface friction: while small and large levels of\nroughness make the system less unstable than the frictionless system, the\nopposite happens at medium roughness. On the other hand, such an intermediate\nwindow of roughness values shrinks as inelasticity increases and eventually\ndisappears at a certain value, beyond which the rough-sphere gas is always less\nunstable than the smooth-sphere gas. A comparison with some preliminary\nsimulation results shows a very good agreement for conditions of practical\ninterest."
    },
    {
        "anchor": "The role of the Havriliak-Negami relaxation in the description of local\n  structure of Kohlrausch's function in the frequency domain. Part I: An improved approximation via Havriliak-Negami (HN) functions to the Fourier\nTransform (FT) of certain Weibull distributions, -\\psi_{\\beta}, (the time\nderivative of the Kohlrausch-Williams-Watts function), is given for a large\ninterval of frequencies: \\omega/2\\pi\\in[0,10^{12}] if 0<\\beta\\leq1 and\n\\omega/2\\pi\\in[0,10^{7}] if 1<\\beta\\leq2. The model is free from the usual\nnumerical distortions, or restrictions associated to sampling step and finite\nsize, present in similar adjustments to complex relaxation functions. Further\nindicates that the identification of (FT) Weibull data with a double HN\napproximant, \\psi_{\\beta}\\simeq\\mathcal{A}p_{2}HN, is quite exact locally even\nthough the parameters involved should vary adiabatically with the frequency,\ni.e. \\{\\alpha_{1,2},\\gamma_{1,2},\\tau_{1,2},\\lambda\\}(\\omega). This fact is the\nbase for the high sensibility of the parameter models, as functions of \\beta,\nto the available data and sampling associated errors. Presumably is also the\nroot of the different proposals for asymptotic traits of\n\\alpha\\cdot\\gamma(\\beta)_{1,2}|_{\\omega\\rightarrow\\infty} functions found in\nscientific literature.",
        "positive": "Predicting the structure of fluids with piecewise constant interactions:\n  Comparing the accuracy of five efficient integral equation theories: We use molecular dynamics simulations to test integral equation theory\npredictions for the structure of fluids of spherical particles with eight\ndifferent piecewise-constant pair interaction forms comprising a hard core and\na combination of two shoulders and/or wells. Since model pair potentials like\nthese are of interest for discretized or coarse-grained representations of\neffective interactions in complex fluids (e.g., for computationally intensive\ninverse optimization problems), we focus here on assessing how accurately their\nproperties can be predicted by analytical or simple numerical closures\nincluding Percus-Yevick, hypernetted chain, reference hypernetted chain,\nfirst-order mean spherical approximation, and a modified first-order mean\nspherical approximation. To make quantitative comparisons between the predicted\nand simulated radial distribution functions, we introduce a cumulative\nstructural error metric. For equilibrium fluid state points of these models, we\nfind that the reference hypernetted chain closure is the most accurate of the\ntested approximations as characterized by this metric or related thermodynamic\nquantities."
    },
    {
        "anchor": "Regularization of the slip length divergence in water nanoflows by\n  inhomogeneities at the Angstrom scale: We performed non-equilibrium Molecular Dynamics simulations of water flow in\nnano-channels with the aim of discriminating {\\it static} from {\\it dynamic}\ncontributions of the solid surface to the slip length of the molecular flow. We\nshow that the regularization of the slip length divergence at high shear rates,\nformerly attributed to the wall dynamics, is controlled instead by its static\nproperties. Surprisingly, we find that atomic displacements at the Angstrom\nscale are sufficient to remove the divergence of the slip length and realize\nthe no-slip condition. Since surface thermal fluctuations at room temperature\nare enough to generate these displacements, we argue that the no-slip condition\nfor water can be achieved also for ideal surfaces, which do not present any\nsurface roughness.",
        "positive": "Efficient models for micro-swimmers: We propose minimal models of one-, two- and three-dimensional micro-swimmers\nat low Reynolds number with a periodic non-reciprocal motion. These swimmers\nare either \"pushers\" or \"pullers\" of fluid along the swimming axis, or\ncombination of the two, depending on the history of the swimming motion. We\nshow this with a linear three-bead swimmer by analytically evaluating the\nmigration speed and the strength of the dipolar flow induced by its swimming\nmotion. It is found that the distance traveled per cycle and the dipolar flow\ncan be obtained from an integral over the area enclosed by the trajectory of\nthe cycle projected onto a cross-plot of the two distances between beads. Two-\nand three-dimensional model swimmers can tumble by breaking symmetry of the\nswimming motion with respect to the swimming axis, as occurs in the tumbling\nmotion of Escherichia coli or Chlamydomonas, which desynchronize the motions of\ntheir flagella to reorient the swimming direction. We also propose a five-bead\nmodel of a \"corkscrew swimmer\", i.e. with a helical flagellum and a rotary\nmotor attached to the cell body. Our five-bead swimmer is attracted to a nearby\nwall, where it swims clockwise as observed in experiments with bacteria with\nhelical flagella."
    },
    {
        "anchor": "Potentials and challenges of polymer informatics: exploiting machine\n  learning for polymer design: There has been rapidly growing demand of polymeric materials coming from\ndifferent aspects of modern life because of the highly diverse physical and\nchemical properties of polymers. Polymer informatics is an interdisciplinary\nresearch field of polymer science, computer science, information science and\nmachine learning that serves as a platform to exploit existing polymer data for\nefficient design of functional polymers. Despite many potential benefits of\nemploying a data-driven approach to polymer design, there has been notable\nchallenges of the development of polymer informatics attributed to the complex\nhierarchical structures of polymers, such as the lack of open databases and\nunified structural representation. In this study, we review and discuss the\napplications of machine learning on different aspects of the polymer design\nprocess through four perspectives: polymer databases, representation\n(descriptor) of polymers, predictive models for polymer properties, and polymer\ndesign strategy. We hope that this paper can serve as an entry point for\nresearchers interested in the field of polymer informatics.",
        "positive": "Precipitation-Redispersion of Cerium Oxide Nanoparticles with\n  Poly(Acrylic Acid) : Towards Stable Dispersions: We exploit a precipitation-redispersion mechanism for complexation of short\nchain polyelectrolytes with cerium oxide nanoparticles to extend their\nstability ranges. As synthesized, cerium oxide sols at pH 1.4 consist of\nmonodisperse cationic nanocrystalline particles having a hydrodynamic diameter\nof 10 nm and a molecular weight 400000 gmol-1. We show that short chain\nuncharged poly(acrylic acid) at low pH when added to a cerium oxide sols leads\nto macroscopic precipitation. As the pH is increased, the solution\nspontaneously redisperses into a clear solution of single particles with an\nanionic poly(acrylic acid) corona. The structure and dynamics of cerium oxide\nnanosols and their hybrid polymer-inorganic complexes in solution are\ninvestigated by static and dynamic light scattering, X-ray scattering, and by\nchemical analysis. Quantitative analysis of the redispersed sol gives rise to\nan estimate of 40 - 50 polymer chains per particle for stable suspension. This\namount represents 20 % of the mass of the polymer-nanoparticle complexes. This\ncomplexation adds utility to the otherwise unstable cerium oxide dispersions by\nextending the range of stability of the sols in terms of pH, ionic strength and\nconcentration."
    },
    {
        "anchor": "Selective buckling via states of self-stress in topological\n  metamaterials: States of self-stress, tensions and compressions of structural elements that\nresult in zero net forces, play an important role in determining the\nload-bearing ability of structures ranging from bridges to metamaterials with\ntunable mechanical properties. We exploit a class of recently introduced states\nof self-stress analogous to topological quantum states to sculpt localized\nbuckling regions in the interior of periodic cellular metamaterials. Although\nthe topological states of self stress arise in the linear response of an\nidealized mechanical frame of harmonic springs connected by freely-hinged\njoints, they leave a distinct signature in the nonlinear buckling behaviour of\na cellular material built out of elastic beams with rigid joints. The salient\nfeature of these localized buckling regions is that they are indistinguishable\nfrom their surroundings as far as material parameters or connectivity of their\nconstituent elements are concerned. Furthermore, they are robust against a wide\nrange of structural perturbations. We demonstrate the effectiveness of this\ntopological design through analytical and numerical calculations as well as\nbuckling experiments performed on two- and three-dimensional metamaterials\nbuilt out of stacked kagome lattices.",
        "positive": "Interfacial fluid flow for systems with anisotropic roughness: I discuss fluid flow at the interface between solids with anisotropic\nroughness. I show that for randomly rough surfaces with anisotropic roughness,\nthe contact area percolate at the same relative contact area as for isotropic\nroughness, and that the Bruggeman effective medium theory and the critical\njunction theory give nearly the same results for the fluid flow conductivity.\nThis shows that, in most cases, the surface roughness observed at high\nmagnification is irrelevant for fluid flow problems such as the leakage of\nstatic seals, and fluid squeeze-out."
    },
    {
        "anchor": "Activated barrier crossing dynamics of a Janus particle carrying cargo: We numerically study the escape kinetics of a self-propelled Janus particle,\ncarrying a cargo, from a meta-stable state. We assume that the cargo is\nattached to the Janus particle by a flexible harmonic spring. We take into\naccount the effect of velocity field, created in the fluid due to movements of\ndimer's components, by considering space-dependent diffusion tensor (Oseen\ntensor). Our simulation results show that the synchronization between barrier\ncrossing events and rotational relaxation process can enhance escape rate to a\nlarge extent. Also, the load carrying capability of a Janus particle is largely\ncontrolled by its rotational dynamics and self-propulsion velocity. Moreover,\nthe hydrodynamic interaction, conspicuously, enhances the escape rate of the\nJanus-cargo dimer. The most of the important features in escape kinetics have\nbeen justified based on the analytic arguments.",
        "positive": "Dynamics of Force Dipoles in Curved Biological Membranes: We construct a model to explore the hydrodynamic interactions of active\ninclusions in curved biological membranes. The curved membrane is modelled as a\ntwo dimensional layer of highly viscous fluid, surrounded by external solvents\nof different viscosities. The active inclusions are modelled as point force\ndipoles. The point dipole limit is taken along a geodesic of the curved\ngeometry, incorporating the change in orientation of the forces due to\ncurvature. We demonstrate this explicitly for the case of a spherical membrane,\nleading to an analytic solution for the flow generated by a single inclusion.\nWe further show that the flow field features an additional defect of negative\nindex, arising from the membrane topology, which is not present in the planar\nversion of the model. We finally explore the hydrodynamic interactions of a\npair of inclusions in regimes of low and high curvature, as well as situations\nwhere the external fluid outside the membrane is confined. Our study suggests\naggregation of dipoles in curved biological membranes of both low and high\ncurvatures, under strong confinement. However, very high curvatures tend to\ndestroy dipole aggregation, even under strong confinement."
    },
    {
        "anchor": "Adsorption of a random heteropolymer with self-interactions onto an\n  interface: We consider the adsorption of a random heteropolymer onto an interface within\nthe model by Garel et al. [1] by taking into account self-interactions between\nthe monomers. Within the replica trick and by using a self-consistent\npreaveraging procedure we map the adsorption problem onto the problem of\nbinding state of a quantum mechanical Hamiltonian. The analysis of the latter\nis treated within the variational method based on the 2-nd Legendre transform.\nWe have found that self-interactions favor the localization. The effect is\nintensified with decrease of the temperature. Within a model without taking\ninto account the repulsive ternary monomer-monomer interactions we predict a\nreentrant localization transition for large values of the asymmetry of the\nheteropolymer and at low enough temperatures.",
        "positive": "Segregation of polymers under cylindrical confinement: Effects of\n  polymer topology and crowding: Monte Carlo computer simulations are used to study the segregation behaviour\nof two polymers under cylindrical confinement. Using a multiple-histogram\nmethod, the conformational free energy, F, of the polymers was measured as a\nfunction of the centre-of-mass separation distance, \\lambda. We examined the\nscaling of the free energy functions with the polymer length, the length and\ndiameter of the confining cylinder, the polymer topology (i.e. linear vs ring\npolymers), and the packing fraction and size of mobile crowding agents. In the\nabsence of crowders, the observed scaling of F(\\lambda) is similar to that\npredicted using a simple model employing the de~Gennes blob model and the\napproximation that the free energy of overlapping chains in a tube is equal to\nthat of two isolated chains each in a tube of half the cross-sectional area.\nSimulations were used to test the latter approximation and reveal that it\nyields poor quantitative predictions. This, along with generic finite-size\neffects, likely gives rise to the discrepancies between the predicted and\nmeasured values of scaling exponents for F(\\lambda). For segregation in the\npresence of crowding agents, the free energy barrier generally decreases with\nincreasing crowder packing fraction, thus reducing the entropic forces driving\nsegregation. However, for fixed packing fraction, the barrier increases as the\ncrowder/monomer size ratio decreases."
    },
    {
        "anchor": "Effective interactions and phase behaviour for a model clay suspension\n  in an electrolyte: Since the early observation of nematic phases of disc-like clay colloids by\nLangmuir in 1938, the phase behaviour of such systems has resisted theoretical\nunderstanding. The main reason is that there is no satisfactory generalization\nfor charged discs of the isotropic DLVO potential describing the effective\ninteractions between a pair of spherical colloids in an electrolyte. In this\ncontribution, we show how to construct such a pair potential, incorporating\napproximately both the non-linear effects of counter-ion condensation (charge\nrenormalization) and the anisotropy of the charged platelets. The consequences\non the phase behaviour of Laponite dispersions (thin discs of 30 nm diameter\nand 1 nm thickness) are discussed, and investigation into the mesostructure via\nMonte Carlo simulations are presented.",
        "positive": "Enhanced dynamics of active Brownian particles in periodic obstacle\n  arrays and corrugated channels: We study the motion of an active Brownian particle (ABP) using overdamped\nLangevin dynamics on a two-dimensional substrate with periodic array of\nobstacles and in a quasi-one-dimensional corrugated channel comprised of\nperiodically arrayed obstacles. The periodic arrangement of the obstacles\nenhances the persistent motion of the ABP in comparison to its motion in the\nfree space. Persistent motion increases with the activity of the ABP. We note\nthat the periodic arrangement induces directionality in ABP motion at late\ntime, and it increases with the size of the obstacles. We also note that the\nABP exhibits a super-diffusive dynamics in the corrugated channel. The\ntransport property is independent of the shape of the channel; rather it\ndepends on the packing fraction of the obstacles in the system. However, the\nABP shows the usual diffusive dynamics in the quasi-one-dimensional channel\nwith flat boundary."
    },
    {
        "anchor": "Liquid-Liquid Crossover in Water Model: Local Structure vs. Kinetics of\n  Hydrogen Bonds: In equilibrium and supercooled liquids, polymorphism is manifested by\nthermodynamic regions defined in the phase diagram, which are predominantly of\ndifferent short- and medium-range order (local structure). It is found that on\nthe phase diagram of the water model, the thermodynamic region corresponding to\nthe equilibrium liquid phase is divided by a line of the smooth liquid-liquid\ncrossover. In the case of the water model, this crossover is revealed by\nvarious local order parameters and corresponds to pressures of the order of\n$3\\,150 \\pm 350$ atm at ambient temperature. In the vicinity of the crossover,\nthe dynamics of water molecules change significantly, which is reflected, in\nparticular, in the fact that the self-diffusion coefficient reaches its maximum\nvalues. In addition, changes in the structure also manifest themselves in\nchanges in the kinetics of hydrogen bonding, which is captured by values of\nsuch the quantities as the average lifetime of hydrogen bonding, the average\nlifetimes of different local coordination numbers, and the frequencies of\nchanges in different local coordination numbers. An interpretation of the\nhydrogen bond kinetics in terms of the free energy landscape concept in the\nspace of possible coordination numbers is proposed.",
        "positive": "Structure of Polypeptide Based Diblock Copolymers in Solution:\n  Stimuli-responsive Vesicles and Micelles: Polypeptide-based diblock copolymers forming either well-defined\nself-assembled micelles or vesicles after direct dissolution in water or in\ndichloromethane, have been studied combining light and neutron scattering with\nelectron microscopy experiments. The size of these structures could be\nreversibly manipulated as a function of environmental changes such as pH and\nionic strength in water. Compared to other pH-responsive seld-assembled systems\nbased on \"classical\" polyelectrolytes, these polypeptide-based nanostructures\npresent the ability to give a response in highly salted media as the chain\nconformational ordering can be controlled. This makes these micelles and\nvesicles suitable for biological applications: they provide significant\nadvantages in the control of the structure and function of supramolecular\nself-assemblies."
    },
    {
        "anchor": "Smoluchowski dynamics and the ergodic-nonergodic transition: We use the recently introduced theory for the kinetics of systems of\nclassical particles to investigate systems driven by Smoluchowski dynamics. We\ninvestigate the existence of ergodic-nonergodic (ENE) transitions near the\nliquid-glass transition. We develop a self-consistent perturbation theory in\nterms of an effective two-body potential. We work to second order in this\npotential. At second order we have an explicit relationship between the static\nstructure factor and the effective potential. We choose the static structure\nfactor in the case of hard spheres to be given by the solution of the\nPercus-Yevick approximation for hard spheres. Then using the analytically\ndetermined ENE equation for the ergodicity function we find an ENE transition\nfor packing fraction, eta, greater than a critical value eta*=0.76 which is\nphysically unaccessible. The existence of a linear fluctuation-dissipation\ntheorem in the problem is shown and used to great advantage.",
        "positive": "A Physics-informed Assembly of Feed-Forward Neural Network Engines to\n  Predict Inelasticity in Cross-Linked Polymers: In solid mechanics, Data-driven approaches are widely considered as the new\nparadigm that can overcome the classic problems of constitutive models such as\nlimiting hypothesis, complexity, and high dependence on training data. However,\nimplementation of machine-learned approaches in material modeling has been\nmodest due to the high-dimensionality of the data space, significant size of\nmissing data, and limited convergence. This work proposes a framework to hire\nconcepts from polymer science, statistical physics, and continuum mechanics to\nprovide super-constrained machine-learning techniques of reduced-order to\novercome many of the existing difficulties. Using a sequential order-reduction,\nwe have simplified the 3D stress-strain tensor mapping problem into a limited\nnumber of super-constrained 1D mapping problems. Next, we introduce an assembly\nof multiple replicated Neural Network agents to systematically classify those\nmapping problems into a few categories, all of which are replications of a few\ndistinct agent types. By capturing all loading modes through a simplified set\nof disperse experimental data, the proposed hybrid assembly of agents provides\na new generation of machine learned approaches that simply outperforms most\nconstitutive laws in training data volume, training speed, and accuracy even in\ncomplicated loading scenarios. Also, it avoids low interpretability of\nconventional AI-based models."
    },
    {
        "anchor": "A Critical Study of Baldelli and Bourdin's On the Asymptotic Derivation\n  of Winkler-Type Energies From 3D Elasticity: In our analysis, we show that Baldelli and Bourdin's work is only valid when\ndescribing the behaviour of a film bonded to an elastic pseudo-foundation,\nwhere Poisson's ratios of both bodies are in between -1 and 0 or in between 0\nand 0.5 (where both Poisson's ratios are sufficiently away from 0 and 0.5), and\nwith an asymptotic condition that is different to what the authors present. We\nalso show that, for all Poisson's ratios, the authors' phase diagram is\nfour-dimensional and not two-dimensional. Also, due to the Poisson's ratio\ndependence, the asymptotic scalings that the authors present are insufficient\nto derive their proposed models. Furthermore, the authors' scaling of the\ndisplacement field implies that their method cannot be applicable to films (or\nstrings) with planar loading, unless the normal displacement is zero. Finally,\nby deriving a Winkler foundation type solution for a plate supported by an\nelastic pseudo-foundation via the method implied by the authors, we show that\nthe authors' method cannot be applied to plates due to the structure of the\noverlying body (i.e. the limits of integration of the plate) and the foundation\n(i.e. planar-stress free condition of the foundation), unless planar\ndisplacement field is identically zero. Despite the limitations of the authors'\nwork, we highlight its strength by showing that unlike the classical derivation\nof the Winkler foundation equation, Baldelli and Bourdin's approach does not\nviolate the volume conversation laws or violate the governing equations of\nmathematical elasticity.",
        "positive": "Single Polymer Confinement in a Slit: Correlation between structure and\n  dynamics: In this paper, we construct an effective model for the dynamics of an\nexcluded-volume chain under confinement, by extending the formalism of Rouse\nmodes. We make specific predictions about the behavior of the modes for a\nsingle polymer confined to a slit. The results are tested against Monte Carlo\nsimulations using the bond-fluctuation algorithm which uses a lattice\nrepresentation of the polymer chain with excluded-volume effects."
    },
    {
        "anchor": "Jet-induced 2-D crater formation with horizontal symmetry breaking: We investigate the formation of a crater in a 2-D bed of granular material by\na jet of impinging gas, motivated by the problem of a retrograde rocket landing\non a planetary surface. The crater is characterized in terms of depth and shape\nas it evolves, as well as by the horizontal position of the bottom of the\ncrater. The crater tends to grow logarithmically in time, a result which is\ncommon in related experiments. We also observe a horizontal symmetry breaking\nat certain well-defined conditions which, as we will demonstrate, could be of\nconsiderable practical concern for lunar or planetary landers. We present data\non the evolution of these asymmetric states and attempt to give insights into\nthe mechanism behind the symmetry-breaking bifurcation.",
        "positive": "Multiphonon anharmonic decay of a quantum mode: A nonperturbative theory of multiphonon anharmonic transitions between energy\nlevels of a local mode is presented. It is shown that the rate of transitions\nrearranges near the critical level number $n_{cr}$: at smaller $n$ the process\nslows down, while at larger $n$ it accelerates in time, causing a jump-like\nloss of energy followed by the generation of phonon bursts. Depending on\nparameters, phonons are emitted in pairs, triplets etc."
    },
    {
        "anchor": "Mapping atomistic to coarse-grained polymer models using automatic\n  simplex optimization to fit structural properties: We develop coarse-grained force fields for poly (vinyl alcohol) and poly\n(acrylic acid) oligomers. In both cases, one monomer is mapped onto a\ncoarse-grained bead. The new force fields are designed to match structural\nproperties such as radial distribution functions of various kinds derived by\natomistic simulations of these polymers. The mapping is therefore constructed\nin a way to take into account as much atomistic information as possible. On the\ntechnical side, our approach consists of a simplex algorithm which is used to\noptimize automatically non-bonded parameters as well as bonded parameters.\nBesides their similar conformation (only the functional side group differs),\npoly (acrylic acid) was chosen to be in aqueous solution in contrast to a poly\n(vinyl alcohol) melt. For poly (vinyl alcohol) a non-optimized bond angle\npotential turns out to be sufficient in connection with a special, optimized\nnon-bonded potential. No torsional potential has to be applied here. For poly\n(acrylic acid), we show that each peak of the radial distribution function is\nusually dominated by some specific model parameter(s). Optimization of the bond\nangle parameters is essential. The coarse-grained forcefield reproduces the\nradius of gyration of the atomistic model. As a first application, we use the\nforce field to simulate longer chains and compare the hydrodynamic radius with\nexperimental data.",
        "positive": "Effect of adhesive interaction on strain stiffening and dissipation in\n  granular gels undergoing yielding: Stress induced yielding/fluidization in disordered solids, characterized by\nirreversibility and enhanced dissipation, is important for a wide range of\nindustrial and geological processes. Although, such phenomena in thermal\nsystems have been extensively studied, they remain poorly understood for\ngranular solids. Here, using oscillatory shear rheology and in-situ optical\nimaging, we study energy dissipation in a dense granular suspension of adhesive\nparticles that forms yield stress solids far below the isotropic jamming point\nobtained in the limit of hard-sphere repulsion. We find interesting non-linear\nflow regimes including intra-cycle strain stiffening and plasticity that\nstrongly depend on the applied strain amplitude ($\\gamma_0$) and particle\nvolume fraction ($\\phi$). We demonstrate that such nonlinearity over the entire\nparameter range can be effectively captured by a dimensionless variable termed\nas the normalized energy dissipation ($E_N$). Furthermore, in-situ optical\nimaging reveals irreversible particle rearrangements correlating with the\nspatiotemporal fluctuations in local velocity, the nature of which strikingly\nvaries across the yielding transition. By directly measuring the critical\njamming packing fractions using particle settling experiments, we propose a\ndetailed phase diagram that unravels the role of inter-particle interactions in\ncontrolling the flow properties of the system for a wide range of $\\gamma_0$\nand $\\phi$ values."
    },
    {
        "anchor": "Towards A Consistent Modeling Of Protein Thermodynamic And Kinetic\n  Cooperativity: How Applicable Is The Transition State Picture To Folding and\n  Unfolding?: To what extent do general features of folding/unfolding kinetics of small\nglobular proteins follow from their thermodynamic properties? To address this\nquestion, we investigate a new simplifed protein chain model that embodies a\ncooperative interplay between local conformational preferences and hydrophobic\nburial. The present four-helix-bundle 55mer model exhibits proteinlike\ncalorimetric two-state cooperativity. It rationalizes native-state hydrogen\nexchange observations. Our analysis indicates that a coherent, self-consistent\nphysical account of both the thermodynamic and kinetic properties of the model\nleads naturally to the concept of a native state ensemble that encompasses\nconsiderable confomational fluctuations. Such a multiple-conformation native\nstate is seen to involve conformational states similar to those revealed by\nnative-state hydrogen exchange. Many of these conformational states are\npredicted to lie below native baselines commonly used in interpreting\ncalorimetric data. Folding and unfolding kinetics are studied under a range of\nintrachain interaction strengths as in experimental chevron plots. Kinetically\ndetermined transition midpoints match well with their thermodynamic\ncounterparts. Kinetic relaxations are found to be essentially single\nexponential over an extended range of model interaction strengths. This\nincludes the entire unfolding regime and a significant part of a folding regime\nwith ...",
        "positive": "Aging as dynamics in configuration space: The relaxation dynamics of many disordered systems, such as structural\nglasses, proteins, granular materials or spin glasses, is not completely frozen\neven at very low temperatures. This residual motion leads to a change of the\nproperties of the material, a process commonly called aging. Despite recent\nadvances in the theoretical description of such aging processes, the\nmicroscopic mechanisms leading to the aging dynamics are still a matter of\ndispute. In this Letter we investigate the aging dynamics of a simple glass\nformer by means of molecular dynamics computer simulation. Using the concept of\nthe inherent structure we give evidence that aging dynamics can be understood\nas a decrease of the effective configurational temperature T of the system.\n  From our results we conclude that the equilibration process is faster when\nthe system is quenched to T_c, the critical T of mode-coupling theory, and that\nthermodynamic concepts are useful to describe the out-of-equilibrium aging\nprocess."
    },
    {
        "anchor": "Static and dynamic heterogeneities in a model for irreversible gelation: We study the structure and the dynamics in the formation of irreversible gels\nby means of molecular dynamics simulation of a model system where the gelation\ntransition is due to the random percolation of permanent bonds between\nneighboring particles. We analyze the heterogeneities of the dynamics in terms\nof the fluctuations of the intermediate scattering functions: In the sol phase\nclose to the percolation threshold, we find that this dynamical susceptibility\nincreases with the time until it reaches a plateau. At the gelation threshold\nthis plateau scales as a function of the wave vector $k$ as $k^{\\eta -2}$, with\n$\\eta$ being related to the decay of the percolation pair connectedness\nfunction. At the lowest wave vector, approaching the gelation threshold it\ndiverges with the same exponent $\\gamma$ as the mean cluster size. These\nfindings suggest an alternative way of measuring critical exponents in a system\nundergoing chemical gelation.",
        "positive": "Perturbation Theory for Path Integrals of Stiff Polymers: The wormlike chain model of stiff polymers is a nonlinear $\\sigma$-model in\none spacetime dimension in which the ends are fluctuating freely. This causes\nimportant differences with respect to the presently available theory which\nexists only for periodic and Dirichlet boundary conditions. We modify this\ntheory appropriately and show how to perform a systematic large-stiffness\nexpansions for all physically interesting quantities in powers of $L/\\xi$,\nwhere $L$ is the length and $\\xi$ the persistence length of the polymer. This\nrequires special procedures for regularizing highly divergent Feynman integrals\nwhich we have developed in previous work. We show that by adding to the\nunperturbed action a correction term ${\\cal A}^{\\rm corr}$, we can calculate\nall Feynman diagrams with Green functions satisfying Neumann boundary\nconditions. Our expansions yield, order by order, properly normalized\nend-to-end distribution function in arbitrary dimensions $d$, its even and odd\nmoments, and the two-point correlation function."
    },
    {
        "anchor": "Adaptive active Brownian particles searching for targets of unknown\n  positions: Developing behavioral policies designed to efficiently solve target-search\nproblems is a crucial issue both in nature and in the nanotechnology of the\n21st century. Here, we characterize the target-search strategies of simple\nmicroswimmers in a homogeneous environment containing sparse targets of unknown\npositions. The microswimmers are capable of controlling their dynamics by\nswitching between Brownian motion and an active Brownian particle and by\nselecting the time duration of each of the two phases. The specific conduct of\na single microswimmer depends on an internal decision-making process determined\nby a simple neural network associated with the agent itself. Starting from a\npopulation of individuals with random behavior, we exploit the genetic\nalgorithm NeuroEvolution of Augmenting Topologies to show how an evolutionary\npressure based on the target-search performances of single individuals helps to\nfind the optimal duration of the two different phases. Our findings reveal that\nthe optimal policy strongly depends on the magnitude of the particle's\nself-propulsion during the active phase and that a broad spectrum of network\ntopology solutions exists, differing in the number of connections and hidden\nnodes.",
        "positive": "Freezing of parallel hard cubes with rounded edges: The freezing transition in a classical three-dimensional system of parallel\nhard cubes with rounded edges is studied by computer simulation and\nfundamental-measure density functional theory. By switching the rounding\nparameter s from zero to one, one can smoothly interpolate between cubes with\nsharp edges and hard spheres. The equilibrium phase diagram of rounded parallel\nhard cubes is computed as a function of their volume fraction and the rounding\nparameter s. The second order freezing transition known for oriented cubes at s\n= 0 is found to be persistent up to s = 0.65. The fluid freezes into a\nsimple-cubic crystal which exhibits a large vacancy concentration. Upon a\nfurther increase of s, the continuous freezing is replaced by a first-order\ntransition into either a sheared simple cubic lattice or a deformed\nface-centered cubic lattice with two possible unit cells: body-centered\northorhombic or base-centered monoclinic. In principle, a system of parallel\ncubes could be realized in experiments on colloids using advanced synthesis\ntechniques and a combination of external fields."
    },
    {
        "anchor": "Stiffer double-stranded DNA in two-dimensional confinement due to\n  bending anisotropy: Using analytical approach and Monte-Carlo (MC) simulations, we study the\nelastic behaviour of the intrinsically twisted elastic ribbons with bending\nanisotropy, such as double-stranded DNA (dsDNA), in two-dimensional (2D)\nconfinement. We show that, due to the bending anisotropy, the persistence\nlength of dsDNA in 2D conformations is always greater than 3D conformations.\nThis result is in consistence with the measured values for DNA persistence\nlength in 2D and 3D in equal biological conditions. We also show that in 2D, an\nanisotropic, intrinsically twisted polymer exhibits an implicit twist-bend\ncoupling, which leads to the kink formations with a half helical turn\nperiodicity along the bent polymer.",
        "positive": "Block Copolymers in Electric Fields: A Comparison of Single-Mode and\n  Self-Consistent Field Approximations: We compare two theoretical approaches to dielectric diblock copolymer melts\nin an external electric field. The first is a relatively simple analytic\nexpansion in the relative copolymer concentration, and includes the full\nelectrostatic contribution consistent with that expansion. It is valid close to\nthe order-disorder transition point, the weak segregation limit. The second\nemploys self-consistent field (SCF) theory and includes the full electrostatic\ncontribution to the free energy at any copolymer segregation. It is more\naccurate but computationally more intensive. Motivated by recent experiments,\nwe explore a section of the phase diagram in the three-dimensional parameter\nspace of the block architecture, the interaction parameter and the external\nelectric field. The relative stability of the lamellar, hexagonal and distorted\nbody-centered-cubic (bcc) phases is compared within the two models. As function\nof an increasing electric field, the distorted bcc region in the phase diagram\nshrinks and disappears above a triple point, at which the lamellar, hexagonal\nand distorted bcc phases coexist. We examine the deformation of the bcc phase\nunder the influence of the external field. While the elongation of the spheres\nis larger in the one-mode expansion than that predicted by the full SCF theory,\nthe general features of the schemes are in satisfactory agreement. This\nindicates the general utility of the simple theory for exploratory\ncalculations."
    },
    {
        "anchor": "Interplay of curvature and rigidity in shape-based models of confluent\n  tissue: Rigidity transitions in simple models of confluent cells have been a powerful\norganizing principle in understanding the dynamics and mechanics of dense\nbiological tissue. In this work we explore the interplay between geometry and\nrigidity in two-dimensional vertex models confined to the surface of a sphere.\nBy considering shapes of cells defined by perimeters whose magnitude depends on\ngeodesic distances and areas determined by spherical polygons, the critical\nshape index in such models is affected by the size of the cell relative to the\nradius of the sphere on which it is embedded. This implies that cells can\ncollectively rigidify by growing the size of the sphere, i.e. by tuning the\ncurvature of their domain. Finite-temperature studies indicate that cell\nmotility is affected well away from the zero-temperature transition point.",
        "positive": "Hydrodynamic collective effects of active proteins in biological\n  membranes: Lipid bilayers forming biological membranes are known to behave as viscous 2D\nfluids on submicrometer scales; usually they contain a large number of active\nprotein inclusions. Recently, it has been shown [Proc. Nat. Acad. Sci. USA 112,\nE3639 (2015)] that such active proteins should in- duce non-thermal fluctuating\nlipid flows leading to diffusion enhancement and chemotaxis-like drift for\npassive inclusions in biomembranes. Here, a detailed analytical and numerical\ninvestigation of such effects is performed. The attention is focused on the\nsituations when proteins are concentrated within lipid rafts. We demonstrate\nthat passive particles tend to become attracted by active rafts and are\naccumulated inside them."
    },
    {
        "anchor": "Temperature-driven volume transition in hydrogels: phase--coexistence\n  and interface localization: We study volume transition phenomenon in hydrogels within the framework of\nFlory-Rehner thermodynamic modelling; we show that starting from different\nmodels for the Flory parameter different conclusions can be achieved, in terms\nof admissible coexisting equilibria of the system. In particular, with explicit\nreference to a one-dimensional problem we establish the ranges of both\ntemperature and traction which allow for the coexistence of a swollen and a\nshrunk phase. Through consideration of an augmented Flory-Rehner free-energy,\nwhich also accounts for the gradient of volume changes, we determine the\nposition of the interface between the coexisting phases, and capture the\nconnection profile between them.",
        "positive": "Synchronization of rotating helices by hydrodynamic interactions: Some types of bacteria use rotating helical flagella to swim. The motion of\nsuch organisms takes place in the regime of low Reynolds numbers where viscous\neffects dominate and where the dynamics is governed by hydrodynamic\ninteractions. Typically, rotating flagella form bundles, which means that their\nrotation is synchronized. The aim of this study is to investigate whether\nhydrodynamic interactions can be at the origin of such a bundling and\nsynchronization. We consider two stiff helices that are modelled by rigidly\nconnected beads, neglecting any elastic deformations. They are driven by\nconstant and equal torques, and they are fixed in space by anchoring their\nterminal beads in harmonic traps. We observe that, for finite trap strength,\nhydrodynamic interactions do indeed synchronize the helix rotations. The speed\nof phase synchronization decreases with increasing trap stiffness. In the limit\nof infinite trap stiffness, the speed is zero and the helices do not\nsynchronize."
    },
    {
        "anchor": "Imaging Temperature and Thickness of Thin Planar Liquid Water Jets in\n  Vacuum: We present spatially resolved measurements of the temperature of a flat\nliquid water microjet for varying pressures, from vacuum to 100% relative\nhumidity. The entire jet surface is probed in a single shot by a\nhigh-resolution infrared camera. Obtained 2D images are substantially\ninfluenced by the temperature of the apparatus on the opposite side of the IR\ncamera; a protocol to correct for the thermal background radiation is\npresented. In vacuum, we observe cooling rates due to water evaporation on the\norder of 105 K/s. For our system, this corresponds to a temperature decrease of\napproximately 15 K between upstream and downstream positions of the flowing\nleaf. Making reasonable assumptions on the absorption of the thermal background\nradiation in the flatjet we can extend our analysis to infer a thickness map.\nFor a reference system our value for the thickness is in good agreement with\nthe one reported from white light interferometry.",
        "positive": "Primary and Secondary Hydration Forces between Interdigitated Membranes\n  Composed of Bolaform Microbial Glucolipids: To better understand lipid membranes in living organisms, the study of\nintermolecular forces using the osmotic pressure technique applied to model\nlipid membranes has constituted the ground knowledge in the field of biophysics\nsince four decades. However, the study of intermolecular forces in lipid\nsystems other than phospholipids, like glycolipids, has gained a certain\ninterest only recently. Even in this case, the work generally focuses on the\nstudy of membrane glycolipids, but little is known on new forms of non-membrane\nfunctional compounds, like microbial bolaform glycolipids. This works explores,\nthrough the osmotic stress method involving an adiabatic humidity chamber\ncoupled to neutron diffraction, the short-range (< 2 nm) intermolecular forces\nof membranes entirely composed of interdigitated glucolipids. Experiments are\nperformed at pH 6, when the glucolipid is partially negatively charged and for\nwhich we explore the effect of low (16 mM) and high (100 mM) ionic strength. We\nfind that this system is characterized by primary and secondary hydration\nregimes, respectively insensitive and sensitive to ionic strength and with\ntypical decay lengths of 0.37 +- 0.12 nm and 1.97 +- 0.78 nm."
    },
    {
        "anchor": "Topological phase transitions in 2-dimensional bent-core liquid crystal\n  models: Spontaneous onset of a low temperature topologically ordered phase in a\n2-dimensional (2D) lattice model of uniaxial liquid crystal (LC) was debated\nextensively pointing to a suspected underlying mechanism affecting the RG flow\nnear the topological fixed point. A recent MC study clarified that a prior\ncrossover leads to a transition to nematic phase. The crossover was interpreted\nas due to the onset of a perturbing relevant scaling field originating from the\nextra spin degree of freedom. As a counter example and in support of this\nhypothesis, we now consider V-shaped bent-core molecules with rigid rod-like\nsegments connected at an assigned angle. The two segments of the molecule\ninteract with the segments of all the nearest neighbours on a square lattice,\nprescribed by a biquadratic interaction. We compute equilibrium averages of\ndifferent observables with Monte Carlo techniques as a function of temperature\nand sample size. For the chosen molecular bend angle and symmetric\ninter-segment interaction between neighbouirng molecules, the 2D system shows\ntwo transitions as a function of T: the higher one at T1 leads to a topological\nordering of defects associated with the major molecular axis without a\ncrossover, imparting uniaxial symmetry to the medium described by the first\nfundamental group of the order parameter space $\\pi_{1}$= $Z_{2}$ (inversion\nsymmetry). The second at T2 leads to a medium displaying biaxial symmetry with\n$\\pi_{1}$ = Q (quaternion group). The biaxial phase shows a self-similar\nmicroscopic structure with the three axes showing power law correlations with\nvanishing exponents as the temperature decreases.",
        "positive": "Inverse design of two-dimensional structure by self-assembly of patchy\n  particles: We propose an optimisation method for the inverse structural design of\nself-assembly of anisotropic patchy particles. The anisotropic interaction can\nbe expressed by the spherical harmonics of the surface pattern on a patchy\nparticle, and thus arbitrary symmetry of the patch can be treated. The pairwise\ninteraction potential includes several to-be-optimised parameters, which are\nthe coefficient of each term in the spherical harmonics. We use the\noptimisation method based on the relative entropy approach and generate\nstructures by Brownian Dynamics simulations. Our method successfully estimates\nthe parameters in the potential for the target structures, such as square\nlattice, kagome lattice, and dodecagonal quasicrystal."
    },
    {
        "anchor": "Effect of shear flow on Wormlike micelles: We use a hybrid method that combines the Multiparticle collision dynamics\n(MPCD) for solvent particles with the molecular dynamics for equilibrium\npolymers to simulate the shearing of the equilibrium polymers (or Wormlike\nmicelles) at a mesoscopic length scale. The MPCD method incorporates the\nhydrodynamic interaction with the polymeric chains. We show successful\nimplementation of the method on the model equilibrium polymers (or Wormlike\nmicelles) and observe that the order of the Iso-Nem transition of the polymeric\nsystem is affected by the shear rate. Moreover, the chains of the equilibrium\npolymers first increase in their average length with the increase in shear rate\nbut then show a decrease in their average length after crossing a particular\nvalue of the shear rate which shows the breaking of chains due to shear stress\nwhen their nematic order remains unchanged. This model and method can be\nfurther used to investigate the shear banding in Wormlike micelles or other\ninteresting properties of such systems.",
        "positive": "Computer-Generated Holographic Optical Tweezer Arrays: Holographic techniques significantly extend the capabilities of laser\ntweezing, making possible extended trapping patterns for manipulating large\nnumbers of particles and volumes of soft matter. We describe practical methods\nfor creating arbitrary configurations of optical tweezers using\ncomputer-generated diffractive optical elements. While the discussion focuses\non ways to create planar arrays of identical tweezers, the approach can be\ngeneralized to three-dimensional arrangements of heterogeneous tweezers and\nextended trapping patterns."
    },
    {
        "anchor": "Understanding the swap Monte Carlo algorithm in a size-polydisperse\n  model glassformer: The dynamics of a polydisperse model glassformer are investigated by\naugmenting molecular dynamics (MD) simulation with swap Monte Carlo (SMC).\nThree variants of the SMC algorithm are analyzed with regard to convergence and\nperformance. We elucidate the microscopic mechanism responsible for the drastic\nspeed-up of structural relaxation at low temperature. It manifests in a\nstepwise increase of the mean squared displacement when the time scale between\nthe application of swap sweeps is significantly larger than a characteristic\nmicroscopic time scale. Compared to Newtonian dynamics, with the hybrid MD-SMC\ndynamics the glass transition shifts to a lower temperature and a different\ntemperature dependence of the localization length is found.",
        "positive": "Contractility-induced phase separation in active solids: A combination of cellular contractility and active phase separation in\ncell-matrix composites is thought to be an enabler of spatiotemporal patterning\nin multicellular tissues across scales, from somitogenesis to cartilage\ncondensation. To characterize these phenomena, we provide a general theory that\nincorporates active cellular contractility into the classical\nCahn--Hilliard-Larch{\\'e} model for phase separation in passive viscoelastic\nsolids. We investigate the dynamics of phase separation in this model and show\nhow a homogeneous mixture can be destabilized by activity via either a\npitchfork or Hopf bifurcation, resulting in stable phase separation and/or\ntraveling waves. Numerical simulations of the full equations allow us to track\nthe evolution of the resulting self-organized patterns, in both periodic and\nmechanically constrained domains, and in different geometries. Altogether, our\nstudy underscores the importance of integrating both cellular activity and\nmechanical phase separation in understanding patterning in soft, active\nbiosolids, and might explain previous experimental observations of cartilage\ncondensation in both in-vivo and in-vitro settings."
    },
    {
        "anchor": "Ligand-Induced Incompatible Curvatures Control Ultrathin Nanoplatelet\n  Polymorphism and Chirality: The ability of thin materials to shape-shift is a common occurrence that\nleads to dynamic pattern formation and function in natural and man-made\nstructures. However, harnessing this concept to design inorganic structures at\nthe nanoscale rationally has remained far from reach due to a lack of\nfundamental understanding of the essential physical components. Here, we show\nthat the interaction between organic ligands and the nanocrystal surface is\nresponsible for the full range of chiral shapes seen in colloidal\nnanoplatelets. The adsorption of ligands results in incompatible curvatures on\nthe top and bottom surfaces of NPL, causing them to deform into helico\\\"ids,\nhelical ribbons, or tubes depending on the lateral dimensions and\ncrystallographic orientation of the NPL. We demonstrate that nanoplatelets\nbelong to the broad class of geometrically frustrated assemblies and exhibit\none of their hallmark features: a transition between helico\\\"ids and helical\nribbons at a critical width. The effective curvature $\\bar{\\kappa}$ is the\nsingle aggregate parameter that encodes the details of the ligand/surface\ninteraction, determining the nanoplatelets' geometry for a given width and\ncrystallographic orientation. The conceptual framework described here will aid\nthe rational design of dynamic, chiral nanostructures with high fundamental and\npractical relevance.",
        "positive": "Two-dimensional Brownian motion of anisotropic dimers: We study the 2D motion of colloidal dimers by single-particle tracking and\ncompare the experimental observations obtained by bright-field microscopy to\ntheoretical predictions for anisotropic diffusion. The comparison is based on\nthe mean-square displacements in the laboratory and particle frame as well as\ngeneralizations of the self-intermediate scattering functions, which provide\ninsights into the rotational dynamics of the dimer. The diffusional anisotropy\nleads to a measurable translational-rotational coupling that becomes most\nprominent by aligning the coordinate system with the initial orientation of the\nparticles. In particular, we find a splitting of the time-dependent diffusion\ncoefficients parallel and perpendicular to the long axis of the dimer which\ndecays over the orientational relaxation time. Deviations of the\nself-intermediate scattering functions from pure exponential relaxation are\nsmall but can be resolved experimentally. The theoretical predictions and\nexperimental results agree quantitatively."
    },
    {
        "anchor": "Macroscopic dynamics of a Bose-Einstein condensate containing a vortex\n  lattice: Starting from the equations of rotational hydrodynamics we study the\nmacroscopic behaviour of a trapped Bose-Einstein condensate containing a large\nnumber of vortices. The stationary configurations of the system, the\nfrequencies of the collective excitations and the expansion of the condensate\nare investigated as a function of the angular velocity of the vortex lattice.\nThe time evolution of the condensate and of the lattice geometry induced by a\nsudden deformation of the trap is also discussed and compared with the recent\nexperimental results of P. Engels et al., Phys. Rev. Lett. 89, 100403 (2002).",
        "positive": "Low-temperature statistical mechanics of the QuanTizer problem: fast\n  quenching and equilibrium cooling of the three-dimensional Voronoi Liquid: The Quantizer problem is a tessellation optimisation problem where point\nconfigurations are identified such that the Voronoi cells minimise the second\nmoment of the volume distribution. While the ground state (optimal state) in 3D\nis almost certainly the body-centered cubic lattice, disordered and effectively\nhyperuniform states with energies very close to the ground state exist that\nresult as stable states in an evolution through the geometric Lloyd's algorithm\n[Klatt et al. Nat. Commun., 10, 811 (2019)]. When considered as a statistical\nmechanics problem at finite temperature, the same system has been termed the\n'Voronoi Liquid' by [Ruscher et al. EPL 112, 66003 (2015)]. Here we investigate\nthe cooling behaviour of the Voronoi liquid with a particular view to the\nstability of the effectively hyperuniform disordered state. As a confirmation\nof the results by Ruscher et al., we observe, by both molecular dynamics and\nMonte Carlo simulations, that upon slow quasi-static equilibrium cooling, the\nVoronoi liquid crystallises from a disordered configuration into the\nbody-centered cubic configuration. By contrast, upon sufficiently fast\nnon-equilibrium cooling (and not just in the limit of a maximally fast quench)\nthe Voronoi liquid adopts similar states as the effectively hyperuniform\ninherent structures identified by Klatt et al. and prevents the ordering\ntransition into a BCC ordered structure. This result is in line with the\ngeometric intuition that the geometric Lloyd's algorithm corresponds to a type\nof fast quench."
    },
    {
        "anchor": "Supersolidity of glasses: Supersolidity of glasses is explained as a property of an unusual state of\ncondensed matter. This state is essentially different from both normal and\nsuperfluid solid states. The mechanism of the phenomenon is the transfer of\nmass by tunneling two level systems.",
        "positive": "Deconstructing the glass transition through critical experiments on\n  colloids: The glass transition is the most enduring grand-challenge problem in\ncontemporary condensed matter physics. Here, we review the contribution of\ncolloid experiments to our understanding of this problem. First, we briefly\noutline the success of colloidal systems in yielding microscopic insights into\na wide range of condensed matter phenomena. In the context of the glass\ntransition, we demonstrate their utility in revealing the nature of spatial and\ntemporal dynamical heterogeneity. We then discuss the evidence from colloid\nexperiments in favor of various theories of glass formation that has\naccumulated over the last two decades. In the next section, we expound on the\nrecent paradigm shift in colloid experiments from an exploratory approach to a\ncritical one aimed at distinguishing between predictions of competing\nframeworks. We demonstrate how this critical approach is aided by the discovery\nof novel dynamical crossovers within the range accessible to colloid\nexperiments. We also highlight the impact of alternate routes to glass\nformation such as random pinning, trajectory space phase transitions and\nreplica coupling on current and future research on the glass transition. We\nconclude our review by listing some key open challenges in glass physics such\nas the comparison of growing static lengthscales and the preparation of\nultrastable glasses, that can be addressed using colloid experiments."
    },
    {
        "anchor": "Composition inversion in mixtures of binary colloids and polymer: Understanding the phase behaviour of mixtures continues to pose challenges,\neven for systems that might be considered \"simple\". Here we consider a very\nsimple mixture of two colloidal and one non-adsorbing polymer species which can\nbe simplified even further to a size-asymmetrical binary mixture, in which the\neffective colloid-colloid interactions depend on the polymer concentration. We\nshow that this basic system exhibits surprisingly rich phase behaviour. In\nparticular, we enquire whether such a system features only a liquid-vapor phase\nseparation (as in one-component colloid-polymer mixtures) or whether,\nadditionally, liquid-liquid demixing of two colloidal phases can occur.\nParticle-resolved experiments show demixing-like behaviour, but when combined\nwith bespoke Monte Carlo simulations, this proves illusory, and we reveal that\nonly a single liquid-vapor transition occurs. Progressive migration of the\nsmall particles to the liquid phase as the polymer concentration increases\ngives rise to composition inversion - a maximum in the large particle\nconcentration in the liquid phase. Near criticality the density fluctuations\nare found to be dominated by the larger colloids.",
        "positive": "Motion of a vortex line near the boundary of a semi-infinite uniform\n  condensate: We consider the motion of a vortex in an asymptotically homogeneous\ncondensate bounded by a solid wall where the wave function of the condensate\nvanishes. For a vortex parallel to the wall, the motion is essentially\nequivalent to that generated by an image vortex, but the depleted surface layer\ninduces an effective shift in the position of the image compared to the case of\na vortex pair in an otherwise uniform flow. Specifically, the velocity of the\nvortex can be approximated by $U \\approx (\\hbar/2m)(y_0-\\sqrt 2 \\xi)^{-1}$,\nwhere $y_0$ is the distance from the center of the vortex to the wall, $\\xi$ is\nthe healing length of the condensate and $m$ is the mass of the boson."
    },
    {
        "anchor": "Simplifying Topological Entanglements by Entropic Competition of\n  Slip-Links: Topological entanglements are abundant, and often detrimental, in polymeric\nsystems in biology and materials science. Here we theoretically investigate the\ntopological simplification of knots by diffusing slip-links (SLs), which may\nrepresent biological or synthetic molecules, such as proteins on the genome or\ncyclodextrines in slide-ring gels. We find that SLs entropically compete with\nknots and can localise them, greatly facilitating their downstream\nsimplification by transient strand-crossing. We further show that the\nefficiency of knot localisation strongly depends on the topology of the SL\nnetwork and, informed by our findings, discuss potential strategies to control\nthe topology of biological and synthetic materials.",
        "positive": "Maxwell Tension Supports the Water Bridge: A cylindrical flexible cable made up of pure fluid water can be\nexperimentally spanned across a spatial gap with cable endpoints fixed to the\ntop edges of two glass beakers. The cable has been called a water bridge in\nclose analogy to iron cables employed to build ordinary span bridges. A\nnecessary condition for the construction of a water bridge is that a large\nelectric field exists parallel to and located within the water cable.\nPresently, there is no accepted detailed theory which quantitatively explains\nthe forces which hold up the bridge. Our purpose is to present such theory\nbased on the Maxwell pressure tensor induced by the electric field albeit\nwithin the condensed matter dielectric fluid cable."
    },
    {
        "anchor": "Diffusion Enhancement in Core-softened fluid confined in nanotubes: We study the effect of confinement in the dynamical behavior of a\ncore-softened fluid. The fluid is modeled as a two length scales potential.\nThis potential in the bulk reproduces the anomalous behavior observed in the\ndensity and in the diffusion of liquid water. A series of $NpT$ Molecular\nDynamics simulations for this two length scales fluid confined in a nanotube\nwere performed. We obtain that the diffusion coefficient increases with the\nincrease of the nanotube radius for wide channels as expected for normal\nfluids. However, for narrow channels, the confinement shows an enhancement in\nthe diffusion coefficient when the nanotube radius decreases. This behavior,\nobserved for water, is explained in the framework of the two length scales\npotential.",
        "positive": "Mean properties and Free Energy of a few hard spheres confined in a\n  spherical cavity: We use analytical calculations and event-driven molecular dynamics\nsimulations to study a small number of hard sphere particles in a spherical\ncavity. The cavity is taken also as the thermal bath so that the system\nthermalizes by collisions with the wall. In that way, these systems of two,\nthree and four particles, are considered in the canonical ensemble. We\ncharacterize various mean and thermal properties for a wide range of number\ndensities. We study the density profiles, the components of the local pressure\ntensor, the interface tension, and the adsorption at the wall. This spans from\nthe ideal gas limit at low densities to the high-packing limit in which there\nare significant regions of the cavity for which the particles have no access,\ndue the conjunction of excluded volume and confinement. The contact density and\nthe pressure on the wall are obtained by simulations and compared to exact\nanalytical results. We also obtain the excess free energy for N=4, by using a\nsimulated-assisted approach in which we combine simulation results with the\nknowledge of the exact partition function for two and three particles in a\nspherical cavity."
    },
    {
        "anchor": "Unifying impacts in granular matter from quicksand to cornstarch: A sharp transition between liquefaction and transient solidification is\nobserved during impact on a granular suspension depending on the initial\npacking fraction. We demonstrate, via high-speed pressure measurements and a\ntwo-phase modeling, that this transition is controlled by a coupling between\nthe granular pile dilatancy and the interstitial fluid pressure generated by\nthe impact. Our results provide a generic mechanism for explaining the wide\nvariety of impact responses in particulate media, from dry quicksand in powders\nto impact-hardening in shear-thickening suspensions like cornstarch.",
        "positive": "System-spanning dynamically jammed region in response to impact of\n  cornstarch and water suspensions: We experimentally characterize the impact response of concentrated\nsuspensions of cornstarch and water. We hypothesize that the dynamically jammed\nregion that propagates ahead of the impactor is responsible for the strong\nstress response to impact when it spans between solid boundaries. Using surface\nimaging and particle tracking at the boundary opposite the impactor, we\nobserved that a visible structure and particle flow at the boundary occur with\na delay after impact. We show the delay time is about the same time as the the\nstrong stress response, confirming that the strong stress response results from\ndeformation of the dynamically jammed structure once it spans between the\nimpactor and a solid boundary. A characterization of this strong stress\nresponse is reported in a companion paper (arXiv:1407.0719). We also elaborate\non the structure of the dynamically jammed region once it spans from the\nimpactor to a solid boundary. We observed particle flow in the outer part of\nthe dynamically jammed region at the bottom boundary, with a net transverse\ndisplacement of up to about 5\\% of the impactor displacement, indicating shear\nat the boundary. Direct imaging of the surface of the outer part of the\ndynamically jammed region reveals a change in surface structure that appears\nthe same as the result of dilation in other cornstarch suspensions. Imaging\nalso reveals cracks, like a brittle solid. These observations suggest the\ndynamically jammed structure can temporarily support stress according to an\neffective modulus, like a soil or dense granular material, along a network of\nfrictional contacts between the impactor and solid boundary."
    },
    {
        "anchor": "Elastically driven, intermittent microscopic dynamics in soft solids: Soft solids with tunable mechanical response are at the core of new material\ntechnologies, but a crucial limit for applications is their progressive aging\nover time, which dramatically affects their functionalities. The generally\naccepted paradigm is that such aging is gradual and its origin is in slower\nthan exponential microscopic dynamics, akin to the ones in supercooled liquids\nor glasses. Nevertheless, time- and space-resolved measurements have provided\ncontrasting evidence: dynamics faster than exponential, intermittency, and\nabrupt structural changes. Here we use 3D computer simulations of a microscopic\nmodel to reveal that the timescales governing stress relaxation respectively\nthrough thermal fluctuations and elastic recovery are key for the aging\ndynamics. When thermal fluctuations are too weak, stress heterogeneities\nfrozen-in upon solidification can still partially relax through elastically\ndriven fluctuations. Such fluctuations are intermittent, because of strong\ncorrelations that persist over the timescale of experiments or simulations,\nleading to faster than exponential dynamics.",
        "positive": "Mode-coupling theory predictions for a limited valency attractive\n  square-well model: Recently we have studied, using numerical simulations, a limited valency\nmodel, i.e. an attractive square well model with a constraint on the maximum\nnumber of bonded neighbors. Studying a large region of temperatures $T$ and\npacking fractions $\\phi$, we have estimated the location of the liquid-gas\nphase separation spinodal and the loci of dynamic arrest, where the system is\ntrapped in a disordered non-ergodic state. Two distinct arrest lines for the\nsystem are present in the system: a {\\it (repulsive) glass} line at high\npacking fraction, and a {\\it gel} line at low $\\phi$ and $T$. The former is\nessentially vertical ($\\phi$-controlled), while the latter is rather horizontal\n($T$-controlled) in the $(\\phi-T)$ plane. We here complement the molecular\ndynamics results with mode coupling theory calculations, using the numerical\nstructure factors as input. We find that the theory predicts a repulsive glass\nline -- in satisfactory agreement with the simulation results -- and an\nattractive glass line which appears to be unrelated to the gel line."
    },
    {
        "anchor": "Swelling of responsive-microgels: experiments versus models: Interpenetrated Polymer Network (IPN) microgels of PNIPAM and PAAc have been\ninvestigated and the experimental data have been compared with theoretical\nmodels from the Flory-Rehner theory. We confirm that the swelling behavior of\nPNIPAM microgels is well described by this theory by considering the second\norder approximation for the volume fraction $\\phi$ dependence of the Flory\nparameter $\\chi(\\phi)$. Indeed the Volume-Phase Transition (VPT) of the\nPNIPAM-PAAc IPN microgel at neutral conditions and in D$_2$O solvents can be\nwell described only considering a third-order approximation. Interestingly we\nempirically find that sharper is the transition higher is the order of the\n$\\chi(\\phi)$ relation which has to be considered. Moreover the VPT can be\nexperimentally controlled by tuning the polymer/solvent interactions through pH\nand solvent allowing to directly modify the delicate balance between energetic\nand entropic contributions and to explore the swelling behavior in a wide range\nof environmental conditions. In particular we find that the most advantageous\ncondition for swelling is in water at acidic pH.",
        "positive": "Theta-point universality of polyampholytes with screened interactions: By an efficient algorithm we evaluate exactly the disorder-averaged\nstatistics of globally neutral self-avoiding chains with quenched random charge\n$q_i=\\pm 1$ in monomer i and nearest neighbor interactions $\\propto q_i q_j$ on\nsquare (22 monomers) and cubic (16 monomers) lattices. At the theta transition\nin 2D, radius of gyration, entropic and crossover exponents are well compatible\nwith the universality class of the corresponding transition of homopolymers.\nFurther strong indication of such class comes from direct comparison with the\ncorresponding annealed problem. In 3D classical exponents are recovered. The\npercentage of charge sequences leading to folding in a unique ground state\napproaches zero exponentially with the chain length."
    },
    {
        "anchor": "Effect of the number of patches on the growth of networks of patchy\n  colloids on substrates: We investigate numerically the irreversible aggregation of patchy spherical\ncolloids on a flat substrate. We consider $n$-patch particles and characterize\nthe dependence of the irreversible aggregation kinetics on $n$. For all values\nof $n$, considered in this study, the growing interface of the aggregate is in\nthe Kardar-Parisi-Zhang universality class, although the bulk structure\nexhibits a rich dependence on $n$. In particular, the bulk density varies with\n$n$ and the network is more ordered for particles with fewer patches. Preferred\norientations of the bonds are also observed for networks of particles with low\n$n$.",
        "positive": "Ultrasoft primitive model of polyionic solutions: structure,\n  aggregation, and dynamics: We introduce an ultrasoft core model of interpenetrating polycations and\npolyanions with continuous Gaussian charge distributions, to investigate\npolyelectrolyte aggregation in dilute and semi-dilute, salt-free solutions. The\nmodel is studied by a combination of approximate theories (random phase\napproximation and hypernetted chain theory) and numerical simulations. The\ncalculated pair structure, thermodynamics, phase diagram and polyion dynamics\nof the symmetric version of the model (the \"ultrasoft restricted primitive\nmodel\" or UPRM) differ from the corresponding properties of the widely studied\n\"restricted primitive model\" (RPM) where ions have hard cores. At sufficiently\nlow temperatures and densities, oppositely charged polyions form weakly\ninteracting, polarizable neutral pairs. The clustering probabilities,\ndielectric behavior and electrical conductivity point to a line of sharp\nconductor-insulator transitions in the density-temperature plane. At very low\ntemperatures the conductor-insulator transition line terminates near the top of\na first order coexistence curve separating a high-density, liquid phase from a\nlow-density, vapor phase. The simulation data hint at a tricritical behavior,\nreminiscent of that observed of the two-dimensional Coulomb Gas, which\ncontrasts with the Ising criticality of its three-dimensional counterpart, the\nRPM."
    },
    {
        "anchor": "The connection between polymer collapse and the onset of jamming: Previous studies have shown that the interiors of proteins are densely\npacked, reaching packing fractions that are as large as those found for static\npackings of individual amino-acid-shaped particles. How can the interiors of\nproteins take on such high packing fractions given that amino acids are\nconnected by peptide bonds and many amino acids are hydrophobic with attractive\ninteractions? We investigate this question by comparing the structural and\nmechanical properties of collapsed attractive disk-shaped bead-spring polymers\nto those of three reference systems: static packings of repulsive disks, of\nattractive disks, and of repulsive disk-shaped bead-spring polymers. We show\nthat attractive systems quenched to temperatures below the glass transition $T\n\\ll T_g$ and static packings of both repulsive disks and bead-spring polymers\npossess similar interior packing fractions. Previous studies have shown that\nstatic packings of repulsive disks are isostatic at jamming onset, i.e. the\nnumber of contacts $N_c$ matches the number of degrees of freedom, which\nstrongly influences their mechanical properties. We find that repulsive\npolymers are hypostatic at jamming onset, but effectively isostatic when\nincluding quartic modes. While attractive disk and polymer packings are\nhyperstatic, we identify a definition for interparticle contacts for which they\ncan also be considered as effectively isostatic. As a result, we show that the\nmechanical properties (e.g. scaling of the potential energy with excess contact\nnumber and low-frequency contribution to the density of vibrational modes) of\nweakly attractive disk and polymer packings are similar to those of ${\\it\nisostatic}$ repulsive disk and polymer packings. Our results demonstrate that\nstatic packings generated via attractive collapse or compression of repulsive\nparticles possess similar structural and mechanical properties.",
        "positive": "Interplay between crystallization and glass transition in binary\n  Lennard-Jones mixtures: In this work we explore the interplay between crystallization and glass\ntransition in different binary mixtures by changing their inter-species\ninteraction length and also the composition. We find that only those systems\nwhich form bcc crystal in the equimolar mixture and whose global structure for\nlarger $x_A$ ($x_A=0.6$, where $x_A$ is the mole fraction of the bigger\nparticles) is a mixed fcc+bcc phase, do not crystallize at this higher\ncomposition. However, the systems whose equimolar structure is a variant of fcc\n(NaCl type crystal) and whose global structure at larger $x_A$ is a mixed\nNaCl+fcc phase, crystallize easily to this mixed structure. We find that the\nstability against crystallization of this \"bcc zone\" is due to the frustration\nbetween the locally preferred structure (LPS) and the mixed bcc+fcc crystal.\nOur study suggests that when the global structure is a mixed crystal where a\nsingle species contributes to both the crystal forms and where the two crystal\nforms have large difference in some order parameter related to that species\nthen this induces frustration between the LPS and the global structure. This\nfrustration makes the systems good glass former. When $x_A$ is further\nincreased ($0.70\\leq x_A < 0.90$) the systems show a tendency towards mixed fcc\ncrystal formation. However, the \"bcc zone\" even for this higher composition is\nfound to be sitting at the bottom of a V shaped phase diagram formed by two\ndifferent variants of the fcc crystal structure, leading to its stability\nagainst crystallization."
    },
    {
        "anchor": "Pattern formation in two-dimensional hard-core/soft-shell systems with\n  variable soft shell profiles: Hard-core/soft shell (HCSS) particles have been shown to self-assemble into a\nremarkably rich variety of structures under compression due to the simple\ninterplay between the hard-core and soft-shoulder length scales in their\ninteractions. Most studies in this area model the soft shell interaction as a\nsquare shoulder potential. Although appealing from a theoretical point of view,\nthe potential is physically unrealistic because there is no repulsive force in\nthe soft shell regime, unlike in experimental HCSS systems. To make the model\nmore realistic, here we consider HCSS particles with a range soft shell\npotential profiles beyond the standard square shoulder form and study the model\nusing both minimum energy calculations and Monte Carlo simulations. We find\nthat by tuning density and the soft shell profile, HCSS particles in the thin\nshell regime (i.e., shell to core ratio $r_1/r_0 \\leq \\sqrt{3}$) can form a\nlarge range of structures, including hexagons, chains, squares, rhomboids and\ntwo distinct zig-zag structures. Furthermore, by tuning the density and\n$r_1/r_0$, we find that HCSS particles with experimentally realistic linear\nramp soft shoulder repulsions can form honeycombs and quasicrystals with\n10-fold and 12-fold symmetry. Our study therefore suggests the exciting\npossibility of fabricating these exotic 2D structures experimentally through\ncolloidal self-assembly.",
        "positive": "Large frequency range of negligible transmission in 1D photonic quantum\n  well structures: We show that it is possible to enlarge the range of low transmission in 1D\nphotonic crystals by using photonic quantum well structures. If a defect is\nintroduced in the photonic quantum well structures, defect modes with a very\nhigh quality factor may appear. The transmission of the defect mode is due to\nthe coupling between the eigenmodes of the defect and those at the band edges\nof the constituent photonic crystals."
    },
    {
        "anchor": "Non-deterministic self-assembly with asymmetric interactions: We investigate general properties of non-deterministic self-assembly with\nasymmetric interactions, using a computational model and DNA tile assembly\nexperiments. By contrasting symmetric and asymmetric interactions we show that\nthe latter can lead to self-limiting cluster growth. Furthermore, by adjusting\nthe relative abundance of self-assembly particles in a two-particle mixture, we\nare able to tune the final sizes of these clusters. We show that this is a\nfundamental property of asymmetric interactions, which has potential\napplications in bioengineering, and provides new insights into the study of\ndiseases caused by protein aggregation.",
        "positive": "Quantum mechanics of one-dimensional trapped Tonks gases: Several experimental groups are currently working towards realizing\nquasi-one-dimensional (1D) atom waveguides and loading them with ultracold\natoms. The dynamics becomes truly 1D in a regime (Tonks gas) of low\ntemperatures and densities and large positive scattering lengths for which the\ntransverse mode becomes frozen, in which case the many-body Schrodinger\ndynamics becomes exactly soluble via a Fermi-Bose mapping theorem. In this\npaper we review our recent work on the exact ground state and quantum dynamics\nof 1D Tonks gases and assess the possibility of approaching the Tonks regime\nusing Bessel beam optical dipole traps."
    },
    {
        "anchor": "Probing the entanglement and locating knots in ring polymers: a\n  comparative study of different arc closure schemes: The interplay between the topological and geometrical properties of a polymer\nring can be clarified by establishing the entanglement trapped in any portion\n(arc) of the ring. The task requires to close the open arcs into a ring, and\nthe resulting topological state may depend on the specific closure scheme that\nis followed. To understand the impact of this ambiguity in contexts of\npractical interest, such as knot localization in a ring with non trivial\ntopology, we apply various closure schemes to model ring polymers. The rings\nhave the same length and topological state (a trefoil knot) but have different\ndegree of compactness. The comparison suggests that a novel method, termed the\nminimally-interfering closure, can be profitably used to characterize the arc\nentanglement in a robust and computationally-efficient way. This closure method\nis finally applied to the knot localization problem which is tackled using two\ndifferent localization schemes based on top-down or bottom-up searches.",
        "positive": "Relaxation dynamics of a compressible bilayer vesicle containing highly\n  viscous fluid: We study the relaxation dynamics of a compressible bilayer vesicle with an\nasymmetry in the viscosity of the inner and outer fluid medium. First we\nexplore the stability of the vesicle free energy which includes a coupling\nbetween the membrane curvature and the local density difference between the two\nmonolayers. Two types of instabilities are identified: a small wavelength\ninstability and a larger wavelength instability. Considering the bulk fluid\nviscosity and the inter-monolayer friction as the dissipation sources, we next\nemploy Onsager's variational principle to derive the coupled equations both for\nthe membrane and the bulk fluid. The three relaxation modes are coupled to each\nother due to the bilayer and the spherical structure of the vesicle. Most\nimportantly, a higher fluid viscosity inside the vesicle shifts the cross-over\nmode between the bending and the slipping to a larger value. As the vesicle\nparameters approach toward the unstable regions, the relaxation dynamics is\ndramatically slowed down, and the corresponding mode structure changes\nsignificantly. In some limiting cases, our general result reduces to the\npreviously obtained relaxation rates."
    },
    {
        "anchor": "Two-parameter model predictions and theta-point crossover for\n  linear-polymer solutions: We consider the first few virial coefficients of the osmotic pressure, the\nradius of gyration, the hydrodynamic radius, and the end-to-end distance for a\nmonodisperse polymer solution. We determine the corresponding two-parameter\nmodel functions which parametrize the crossover between the good-solvent and\nthe ideal-chain behavior. These results allow us to predict the osmotic\npressure and the polymer size in the dilute regime in a large temperature\nregion above the theta-point.",
        "positive": "Hydrodynamic instabilities in shear flows of cohesive granular particles: We extend the dynamic van der Waals model introduced by A. Onuki [Phys. Rev.\nLett. 94, 054501 (2005)] to the description of cohesive granular flows under a\nplane shear to study their hydrodynamic instabilities. Numerically solving the\ndynamic van der Waals model, we observe various heterogeneous structures of the\ndensity in steady states, where the viscous heating is balanced with the energy\ndissipation caused by inelastic collisions. Based on the linear stability\nanalysis, we find that the spatial structures are determined by the mean volume\nfraction, the applied shear rate, and the inelasticity, where the instability\nis triggered if the system is thermodynamically unstable, i.e. the pressure,\n$p$, and the volume fraction, $\\phi$, satisfy $\\partial p/\\partial\\phi<0$."
    },
    {
        "anchor": "Implications of the effective one-component analysis of pair\n  correlations in colloidal fluids with polydispersity: Partial pair-correlation functions of colloidal suspensions with continuous\npolydispersity can be challenging to characterize from optical microscopy or\ncomputer simulation data due to inadequate sampling. As a result, it is common\nto adopt an effective one-component description of the structure that ignores\nthe differences between particle types. Unfortunately, whether this kind of\nsimplified description preserves or averages out information important for\nunderstanding the behavior of the fluid depends on the degree of polydispersity\nand can be difficult to assess, especially when the corresponding\nmulticomponent description of the pair correlations is unavailable for\ncomparison. Here, we present a computer simulation study that examines the\nimplications of adopting an effective one-component structural description of a\npolydisperse fluid. The square-well model that we investigate mimics key\naspects of the experimental behavior of suspended colloids with short-range,\npolymer-mediated attractions. To characterize the partial pair-correlation\nfunctions and thermodynamic excess entropy of this system, we introduce a Monte\nCarlo sampling strategy appropriate for fluids with a large number of\npseudo-components. The data from our simulations at high particle\nconcentrations, as well as exact theoretical results for dilute systems, show\nhow qualitatively different trends between structural order and particle\nattractions emerge from the multicomponent and effective one-component\ntreatments, even with systems characterized by moderate polydispersity. We\nexamine consequences of these differences for excess-entropy based scalings of\nshear viscosity, and we discuss how use of the multicomponent treatment reveals\nsimilarities between the corresponding dynamic scaling behaviors of attractive\ncolloids and liquid water that the effective one-component analysis does not\ncapture.",
        "positive": "Inferring global dynamics from local structure in liquid electrolytes: Ion transport in concentrated electrolytes plays a fundamental role in\nelectrochemical systems such as lithium ion batteries. Nonetheless, the\nmechanism of transport amid strong ion-ion interactions remains enigmatic. A\nkey question is whether the dynamics of ion transport can be predicted by the\nlocal static structure alone, and if so what are the key structural motifs that\ndetermine transport. In this paper, we show that machine learning can\nsuccessfully decompose global conductivity into the spatio-temporal average of\nlocal, instantaneous ionic contributions, and relate this ``local molar\nconductivity\" field to the local ionic environment. Our machine learning model\naccurately predicts the molar conductivity of electrolyte systems that were not\npart of the training set, suggesting that the dynamics of ion transport is\npredictable from local static structure. Further, through analysing this\nmachine-learned local conductivity field, we observe that fluctuations in local\nconductivity at high concentration are negatively correlated with total molar\nconductivity. Surprisingly, these fluctuations arise due to a long tail\ndistribution of low conductivity ions, rather than distinct ion pairs, and are\nspatially correlated through both like- and unlike-charge interactions. More\nbroadly, our approach shows how machine learning can aid the understanding of\ncomplex soft matter systems, by learning a function that attributes global\ncollective properties to local, atomistic contributions."
    },
    {
        "anchor": "Measurement of Turbulence in Superfluid 3He-B: The experimental investigation of superfluid turbulence in 3He-B is generally\nnot possible with the techniques which have been developed for 4He-II. We\ndescribe a new method by which a transient burst of turbulent vortex expansion\ncan be generated in 3He-B. It is based on the injection of a few vortex loops\ninto rotating vortex-free flow. The time-dependent evolution of the quantized\nvorticity is then monitored with NMR spectroscopy. Using these techniques the\ntransition between regular (i.e. vortex number conserving) and turbulent vortex\ndynamics can be recorded at T ~ 0.6 Tc and a number of other characteristics of\nturbulence can be followed down to a temperature of T ~ 0.4 Tc.",
        "positive": "Theoretical description of a DNA-linked nanoparticle self-assembly: Nanoparticles tethered with DNA strands are promising building blocks for\nbottom-up nanotechnology, and a theoretical understanding is important for\nfuture development. Here we build on approaches developed in polymer physics to\nprovide theoretical descriptions for the equilibrium clustering and dynamics,\nas well as the self-assembly kinetics of DNA-linked nanoparticles. Striking\nagreement is observed between the theory and molecular modeling of DNA tethered\nnanoparticles."
    },
    {
        "anchor": "Machine learnt approximations to the bridge function yield improved\n  closures for the Ornstein-Zernike equation: A key challenge for soft materials design and coarse-graining simulations is\ndetermining interaction potentials between components that give rise to desired\ncondensed-phase structures. In theory, the Ornstein-Zernike equation provides\nan elegant framework for solving this inverse problem. Pioneering work in\nliquid state theory derived analytical closures for the framework. However,\nthese analytical closures are approximations, valid only for specific classes\nof interaction potentials. In this work, we combine the physics of liquid state\ntheory with machine learning to infer a closure directly from simulation data.\nThe resulting closure is more accurate than commonly used closures across a\nbroad range of interaction potentials. We show for two examples of a\nprototypical inverse design problem, fitting a coarse-grained simulation\npotential, that our approach leads to improved one-step inversion.",
        "positive": "3-dimensional structure of a sheet crumpled into a ball: When a thin sheet is crushed into a small three-dimensional volume, it\ninvariably forms a structure with a low volume fraction but high resistance to\nfurther compression. Being a far-from-equilibrium process, forced crumpling is\nnot necessarily amenable to a statistical description in which the parameters\nof the initially flat sheet and the final confinement fully specify the\nresulting crumpled state. Instead, the internal geometry and mechanical\nproperties of the crumpled ball may reflect the history of its preparation. Our\nX-ray microtomography experiments reveal that the internal 3-dimensional\ngeometry of a crumpled ball is in many respects isotropic and homogeneous. In\nthese respects, crumpling recapitulates other classic nonequilibrium problems\nsuch as turbulence, where a system driven by long-wavelength, low-symmetry,\nforcing shows only rather subtle fingerprints of the forcing mechanism.\nHowever, we find local nematic ordering of the sheet into parallel stacks. The\nlayering proceeds radially inwards from the outer surface. The extent of this\nlayering increases with the volume fraction, or degree of compression."
    },
    {
        "anchor": "Tearing of thin sheets: Cracks interacting through an elastic ridge: We study the interaction between two cracks propagating quasistatically\nduring the tearing of a thin brittle sheet. We show that the cracks attract\neach other following a path described by a power law resulting from the\ncompetition between elastic and fracture energies. The power law exponent\n(8/11) is in close agreement with experiments. We also show that a second\n(asymptotic) regime, with an exponent of 9/8, emerges for small distances\nbetween the two crack tips due to the finite transverse curvature of the\nelastic ridge joining them.",
        "positive": "Exact current blockade maps of dsDNA bound motifs driven through a\n  solitary nanopore using electrokinetic Brownian dynamics: We report current blockade (CB) characteristics of molecular motifs residing\non a model dsDNA using electrokinetic Brownian dynamics (EKBD) and study the\nrole of the valence of the counterions as the dsDNA translocates through a\nsolitary nanopore (NP) driven by an electric field. We explicitly incorporate\nall the charges on the DNA backbone, co- and counter-ions, and investigate CB\ncharacteristics of two charged sidechain motifs exactly. Our simulation brings\nout the details of binding and unbinding of the counter-ions and the time\ndependent counter-ion condensation on the translocating DNA for mono- and\ndi-valent salt conditions. An important and less intuitive finding is that the\ndrop in the conventional (positive) current through the pore is due to the\ncondensation of the counter-ions on the translocating DNA and not so much due\nto drop in the co-ions passing through the pore. This finding aligns with\nprevious studies conducted by Tanaka et al. [Phys. Rev. Lett. 94, 148103\n(2005)], Cui [J. Phys. Chem B 114, 2015 (2010)], and Holm et al. [Phys. Rev.\nLett. 112, 018101 (2014)]. We further find that this condensation is larger for\nthe divalent ions leading to a slowing down of the translocation speed and\nyielding a longer dwell time for the motifs. Finally, we use the exact CB\ncharacteristics from the EKBD simulation to reconstruct the same CB\ncharacteristics using a volumetric ansatz on the segment inside and in the\nvicinity of the pore using on the ordinary BD model without the explicit\npresence of co- and counter-ions. Refinement of this ansatz will allow us to\nobtain the CB characteristics for longer genome fragments using low-cost\nordinary BD simulation."
    },
    {
        "anchor": "Amoeboid movement utilizes the shape coupled bifurcation of an active\n  droplet to boost ballistic motion: One of the essential functions of living organisms is spontaneous migration\nthrough the deformation of their body, such as crawling, swimming, and walking.\nDepending on the size of the object, the efficient migratory mode should be\naltered because the contribution from the inertial and frictional forces acting\non the object switches. Although the self-propelling motion characterizing\nactive matter has been extensively studied, it is still elusive how a living\ncell utilizes the mode switching of the self-propulsion. Here, we studied the\nmigration dynamics of amoeboid movement of free-living amoeba, Amoeba proteus,\nfor starved and vegetative phases, as typified by dynamic and stationary\nstates, respectively. Fourier-mode analysis on the cell shape and migration\nvelocity extracted two characteristic migration modes, which makes a\ncoexistence of amoeboid-swimmer like random motion and the active-droplet like\nballistic motion. While the amoeboid-swimmer mode governs random motion, the\nactive-droplet mode performs non-negligible contribution on the migration\nstrength. By employing the symmetry argument of the active-droplet, we discover\nthe supercritical pitchfork bifurcation of the migration velocity due to the\nsymmetry breaking of the cell shape represents the switching manner from the\nmotionless state to the random and the ballistic motions. Our results suggest\nthat sub-mm sized A. proteus utilizes both shape oscillatory migration of\ndeformed-swimmer driven by surface wave and convection based mass transfer,\ncalled blebbing, as like as cm-sized active droplet to optimize the movement\nefficiency.",
        "positive": "Dry Active Matter exhibits a self-organized 'Cross Sea' Phase: The Vicsek model of self-propelled particles is known in three different\nphases: (i) a polar ordered homogeneous phase also called Toner-Tu phase, (iii)\na phase of polar ordered regularly arranged high density bands (waves) with\nsurrounding low density regions without polar order and (iv) a homogeneous\nphase without polar order. It has been questioned whether the band phase (iii)\nshould be divided into two parts [Chat\\'e2020]: one with periodically arranged\nand one with strongly interacting but not ordered bands. We answer this\nquestion by showing that the standard Vicsek model has a fourth phase for large\nsystem sizes: (ii) a polar ordered cross sea phase. Close to the transition\ntowards (i) this phase becomes unstable and looks like strongly interacting\nbands. We demonstrate that the cross sea phase is not just a superposition of\ntwo waves, but it is an independent complex pattern. Furthermore we show that\nthere is a non-zero mass flow through the structure of the cross sea pattern\nwithin its co-moving frame."
    },
    {
        "anchor": "Chiral Active Matter: Chiral active matter comprises particles which can self-propel and\nself-rotate. Examples range from sperm cells and bacteria near walls to\nasymmetric colloids and pea-shaped Quincke rollers. In this perspective article\nwe focus on recent developments in chiral active matter. After briefly\ndiscussing chiral active motion at a single particle level, we discuss\ncollective phenomena ranging from vortex arrays and patterns made of rotating\nmicro-flocks to states featuring unusual rheological properties.",
        "positive": "Coarse-graining polymer solutions: a critical appraisal of single- and\n  multi-site models: We critically discuss and review the general ideas behind single- and\nmulti-site coarse-grained (CG) models as applied to macromolecular solutions in\nthe dilute and semi-dilute regime. We first consider single-site models with\nzero-density and density-dependent pair potentials. We highlight advantages and\nlimitations of each option in reproducing the thermodynamic behavior and the\nlarge-scale structure of the underlying reference model. As a case study we\nconsider solutions of linear homopolymers in a solvent of variable quality.\nSecondly, we extend the discussion to multi-component systems presenting, as a\ntest case, results for mixtures of colloids and polymers. Specifically, we\nfound the CG model with zero-density potentials to be unable to predict\nfluid-fluid demixing in a reasonable range of densities for mixtures of\ncolloids and polymers of equal size. For larger colloids, the polymer volume\nfractions at which phase separation occurs are largely overestimated. CG models\nwith density-dependent potentials are somewhat less accurate than models with\nzero-density potentials in reproducing the thermodynamics of the system and,\nalthough they presents a phase separation, they significantly underestimate the\npolymer volume fractions along the binodal. Finally, we discuss a general\nmulti-site strategy, which is thermodynamically consistent and fully\ntransferable with the number of sites, and that allows us to overcome most of\nthe limitations discussed for single-site models."
    },
    {
        "anchor": "Thermal analogue of gimbal lock in a colloidal ferromagnetic Janus rod: We report an entropy-driven orientational hopping transition in a\nmagnetically confined colloidal Janus rod. In a magnetic field, the sedimented\nrod randomly hops between horizontal and vertical states: the latter state\ncomes at a substantial gravitational cost at no reduction of magnetic potential\nenergy. The probability distribution over the angles of the rod shows that the\npresence of an external magnetic field leads to the emergence of a metastable\nvertical state separated from the ground state by an effective barrier. This\nbarrier does not come from the potential energy but rather from the vast gain\nin phase space available to the rod as it approaches the vertical state. The\nloss of rotational degree of freedom that gives rise to this effect is a\nstatistical mechanical analogue of the phenomenon of gimbal lock from classical\nmechanics.",
        "positive": "Inertial clustering and emergent phase separation of spherical spinners: We study the hydrodynamics of spherical spinners suspended in a Newtonian\nfluid at inertial regime. We observe a spontaneous condensation of the spinners\ninto particle rich regions, at low but finite particle Reynolds numbers and\nvolume fractions. The particle clusters have a coherent internal dynamics. The\nspinners form colloidal vortices surrounded by the fluid depleted of the\nparticles. The formation of vortices is observed both in periodic simulation\nbox and when the spinners are confined between two flat walls. The\nstabilisation of the observed states relies only on hydrodynamic interactions\nbetween the spinners and requires a finite amount of inertia. The observations\npave the way for the realisation of 3-dimensional spinner materials, where\ncoherent structures and collective dynamics arise only from the rotational\nmotion of the constituents."
    },
    {
        "anchor": "Rotational self-diffusion in suspensions of charged particles: Revised\n  Beenakker-Mazur and Pairwise Additivity methods versus numerical simulations: To the present day, the Beenakker-Mazur (BM) method is the most comprehensive\nstatistical physics approach to the calculation of short-time transport\nproperties of colloidal suspensions. A revised version of the BM method with an\nimproved treatment of hydrodynamic interactions is presented and evaluated\nregarding the rotational short-time self-diffusion coefficient, $D^r$ , of\nsuspensions of charged particles interacting by a hard-sphere plus screened\nCoulomb (Yukawa) pair potential. To assess the accuracy of the method,\nelaborate simulations of $D^r$ have been performed, covering a broad range of\ninteraction parameters and particle concentrations. The revised BM method is\ncompared in addition with results by a simplifying pairwise additivity (PA)\nmethod in which the hydrodynamic interactions are treated on a two-body level.\nThe static pair correlation functions re- quired as input to both theoretical\nmethods are calculated using the Rogers-Young integral equation scheme. While\nthe revised BM method reproduces the general trends of the simulation results,\nit systematically and significantly underestimates the rotational diffusion\ncoefficient. The PA method agrees well with the simulation data at lower volume\nfractions, but at higher concentrations $D^r$ is likewise underestimated. For a\nfixed value of the pair potential at mean particle distance comparable to the\nthermal energy, $D^r$ increases strongly with increasing Yukawa potential\nscreening parameter.",
        "positive": "Shear-stress fluctuations in free-standing polymer films: Using molecular dynamics simulation of a polymer glass model we investigate\nfree-standing polymer films focusing on the in-plane shear modulus $\\mu$ and\nthe corresponding shear-stress relaxation modulus $G(t)$ as functions of\ntemperature $T$, film thickness $H$ (tuned by means of the lateral box size\n$L$) and sampling time $\\Delta t$. Various observables are seen to vary\nlinearly with $1/H$ demonstrating thus the (to leading order) linear\nsuperposition of bulk and surface properties. In agreement with recent studies\non three-dimensional polymer glass-formers, $\\mu$ and $G(t)$ are found to\ndecrease continuously with $T$. A jump-singularity is not observed. Confirming\nthe time-translational invariance of our systems, the $\\Delta t$-dependence of\n$\\mu$ is traced back to $G(t)$."
    },
    {
        "anchor": "Structural properties of water confined by phospholipid membranes: Biological membranes are essential for the cell life and hydration water\nprovides the driving force for their assembly and stability. Here we study the\nstructural properties of water in a phospholipid membrane. We characterize\nlocal structures inspecting the intermediate range order (IRO) adopting a\nsensitive local order metric, recently proposed by Martelli et al., which\nmeasures and grades the degree of overlap of local environments with structures\nof perfect ice. Close to the membrane, water acquires high IRO and changes its\ndynamical properties, e.g., slowing down its translational and rotational\ndegrees of freedom in a region that extends over $\\simeq 1$ nm from the\nmembrane interface. Surprisingly, we show that at a distance as far as $\\simeq\n2.5$ nm from the interface, although the bulk-like dynamics is recovered,\nwater's IRO is still slightly higher than in bulk at the same thermodynamic\nconditions. Therefore, the water-membrane interface has a structural effect at\nambient conditions that propagates further than the often-invoked $1$ nm-length\nscale, a results that should be taken carefully into account when analyzing\nexperimental data of water confined by membranes and could help us\nunderstanding the role of water in biological systems.",
        "positive": "Anomalous Longitudinal Magnetic Field near the Surface of Copper\n  Conductors: We have used ultracold atoms to characterize the magnetic field near the\nsurface of copper conductors at room temperature carrying currents between\n0.045 A and 2 A. In addition to the usual circular field we find an additional,\n1000 - 10000 times smaller longitudinal field. The field changes its strength\nperiodically with a period of 200-300 um."
    },
    {
        "anchor": "Polymer translocation through nanopore assisted by an environment of\n  active rods: We use a combination of computer simulations and iso-flux tension propagation\n(IFTP) theory to investigate translocation dynamics of a flexible linear\npolymer through a nanopore into an environment composed of repulsive active\nrods in 2D. We demonstrate that the rod activity induces a crowding effect on\nthe polymer, leading to a time-dependent net force that facilitates\ntranslocation into the active environment. Incorporating this force into the\nIFTP theory for pore-driven translocation allows us to characterise\ntranslocation dynamics in detail and derive a scaling form for the average\ntranslocation time as $\\tilde{\\tau} \\sim \\tilde{L}_{\\textrm{r}}^{\\nu} /\n\\tilde{F}_{\\textrm{SP}} $, where $\\tilde{L}_{\\textrm{r}}$ and\n$\\tilde{F}_{\\textrm{SP}}$ are the rod length and self-propelling force acting\non the rods, respectively, and $\\nu$ is the Flory exponent.",
        "positive": "The equilibrium intrinsic crystal-liquid interface of colloids: We use confocal microscopy to study an equilibrated crystal-liquid interface\nin a colloidal suspension. Capillary waves roughen the surface, but locally the\nintrinsic interface is sharply defined. We use local measurements of the\nstructure and dynamics to characterize the intrinsic interface, and different\nmeasurements find slightly different widths of this interface. In terms of the\nparticle diameter $d$, this width is either $1.5d$ (based on structural\ninformation) or $2.4d$ (based on dynamics), both not much larger than the\nparticle size. This work is the first direct experimental visualization of an\nequilibrated crystal-liquid interface."
    },
    {
        "anchor": "Lattice Boltzmann modeling of cholesteric liquid crystal droplets under\n  an oscillatory electric field: We numerically study the dynamics of quasi-two dimensional cholesteric liquid\ncrystal droplets in the presence of a time-dependent electric field, rotating\nat constant angular velocity. A surfactant sitting at droplet interface is also\nintroduced to prevent droplet coalescence. The dynamics is modeled following a\nhybrid numerical approach, where a standard lattice Boltzmann technique solves\nthe Navier-Stokes equation and a finite difference scheme integrates the\nevolution equations of liquid crystal and surfactant. Our results show that,\nonce the field is turned on, the liquid crystal rotates coherently triggering a\nconcurrent orbital motion of both droplets around each other, an effect due to\nthe momentum transfer to the surrounding fluid. In addition the topological\ndefects, resulting from the conflict orientation of the liquid crystal within\nthe drops, exhibit a chaotic-like motion in cholesterics with a high pitch, in\ncontrast with a regular one occurring along circular trajectories observed in\nnematics drops. Such behavior is found to depend on magnitude and frequency of\nthe applied field as well as on the anchoring of the liquid crystal at the\ndroplet interface. These findings are quantitatively evaluated by measuring the\nangular velocity of fluid and drops for various frequencies of the applied\nfield.",
        "positive": "Reaching large lengths and long times in polymer dynamics simulations: A lattice model is presented for the simulation of dynamics in polymeric\nsystems. Each polymer is represented as a chain of monomers, residing on a\nsequence of nearest-neighbor sites of a face-centered-cubic lattice. The\npolymers are self- and mutually avoiding walks: no lattice site is visited by\nmore than one polymer, nor revisited by the same polymer after leaving it. The\ndynamics occurs through single-monomer displacements over one lattice spacing.\nTo demonstrate the high computational efficiency of the model, we simulate a\ndense binary polymer mixture with repelling nearest-neighbor interactions\nbetween the two types of polymers, and observe the phase separation over a long\nperiod of time. The simulations consist of a total of 46,080 polymers, 100\nmonomers each, on a lattice with 13,824,000 sites, and an interaction strength\nof 0.1 kT. In the final two decades of time, the domain-growth is found to be\nd(t) ~ t^1/3, as expected for a so-called \"Model B\" system."
    },
    {
        "anchor": "Electric double layers with surface charge modulations: Novel exact\n  Poisson-Boltzmann solutions: Poisson-Boltzmann theory is the cornerstone for soft matter electrostatics.\nWe provide novel exact analytical solutions to this non-linear mean-field\napproach, for the diffuse layer of ions in the vicinity of a planar or a\ncylindrical macroion. While previously known solution are for homogeneously\ncharged objects, the cases worked out exhibit a modulated surface charge --or\nequivalently surface potential-- on the macroion (wall) surface. In addition to\nasymptotic features at large distances from the wall, attention is paid to the\nfate of the contact theorem, relating the contact density of ions to the local\nwall charge density. For salt-free systems (counterions only), we make use of\nresults pertaining to the two-dimensional Liouville equation, supplemented by\nan inverse approach. When salt is present, we invoke the exact two-soliton\nsolution to the 2D sinh-Gordon equation. This leads to inhomogeneous charge\npatterns, that are either localized or periodic in space. Without salt, the\nelectrostatic signature of a charge pattern on the macroion fades exponentially\nwith distance for a planar macroion, while it decays as an inverse power-law\nfor a cylindrical macroion. With salt, our study is limited to the planar\ngeometry, and reveals that pattern screening is exponential.",
        "positive": "Enhancement of coil--stretch hysteresis by self-concentration in\n  extensional flows, and its implications for capillary thinning of liquid\n  bridges of dilute polymer solutions: The coil-stretch transition in extensional flows of viscoelastic dilute\npolymer solutions is known to be associated with a strong hysteresis in\nmolecular conformations and rheo-optical properties. At infinite dilution,\nhysteresis is caused by the large difference in frictional drag coefficient\nbetween undeformed isotropic polymer coils and highly stretched conformations.\nAt the low extension rates in the hysteresis regime, stretched molecules\npervade larger volumes than equilibrium coils since the flow is too weak to\nsuppress transverse fluctuations. The onset of intermolecular overlap occurs\nfor such stretched conformations at polymer concentrations much smaller than\nc*, the conventional critical overlap concentration for equilibrium coils.\nTherefore, for a range of concentrations c < c*, intramolecular hydrodynamic\ninteractions may be significantly screened in stretched conformations. Scaling\narguments based on \"blob\" concepts are used here to argue that the stretched\nstate drag coefficient can grow strongly with concentration in the dilute\nregime. A dumbbell model with conformation-dependent drag model is used to\npredict a concomitant strong enhancement of coil-stretch hysteresis with\nincreasing concentration in the dilute regime. This extensional flow induced\nself-concentration leads to a maximum in hysteretic effects around c*, which\nprogressively diminish in the semi-dilute regime where screening in isotropic\ncoils reduces the difference in drag coefficient between stretched and coiled\nstates. It is shown that the concentration dependence observed by Clasen et al.\n(2006) of capillary-thinning dynamics in liquid bridges of polymer solutions\nprovides direct evidence of coil-stretch hysteresis enhancement by\nself-concentration."
    },
    {
        "anchor": "Seeing Site-Specific Isotopic Labeling of Amino Acids with Vibrational\n  Spectroscopy in the Electron Microscope: Isotope labeling is a fundamental staple for the study of cellular metabolism\nand protein function. The conventional techniques that allow resolution and\nidentification of isotopically-labeled biomarkers, such as mass spectrometry\nand infrared spectroscopy, are macroscopic in nature and have the disadvantage\nof requiring relatively large quantities of material and lacking spatial\nresolution. Here, we record the vibrational spectra of an {\\alpha}-amino acid,\nL-alanine, using spatially-resolved monochromated electron energy loss\nspectroscopy (EELS) to directly resolve carbon-site-specific isotopic labels in\na scanning transmission electron microscope. The EELS is acquired in aloof\nmode, meaning the probe is positioned away from the sample (~20 nm) sparing the\nsensitive biomolecule from the high-energy excitations, while the vibrational\nmodes are investigated. An isotopic red-shift of 5.3 meV was obtained for the\nC=O stretching mode in the carboxylic acid group for 13C-enriched L-alanine\nwhen compared with naturally occurring 12C L-alanine, which is confirmed by\nmacroscopic infrared spectroscopy measurements and theoretical calculations.\nThe EELS experiments presented here are the first demonstration of\nnon-destructive resolution and identification of isotopically-labeled amino\nacids in the electron microscope, opening a new door for the study of\nbiological matter at the nanoscale.",
        "positive": "Emergence of Disordered Hyperuniformity in Melts of Linear Diblock\n  Copolymers: Disordered hyperuniform (DHU) systems are recently discovered exotic states\nof matter, where (normalized) large-scale density fluctuations are completely\nsuppressed as in crystals, even though the systems are isotropic and lack\nconventional long-range order. Despite recent success, realizing such systems\nusing bottom-up approaches remains challenging. Here, we study the large-scale\nbehavior of neat melts of linear diblock copolymers using large-cell\nself-consistent field theory (SCFT) simulations. We initialize SCFT simulations\nusing point patterns that correspond to the local energy minimum of the\nso-called Quantizer energy, a geometric functional related to the free energy\nof copolymeric self-assemblies. Upon relaxation via the SCFT simulations, we\nobtain a new class of metastable disordered micelle mesophases that are\nhyperuniform. Moreover, we find that DHU micelle mesophases possess very\nsimilar free energies to the thermodynamically stable body-centered cubic\nsphere mesophases and are also much more favorable energetically than\npreviously obtained liquid-like packings. Our findings shed light on the design\nof novel disordered hyperuniform materials using bottom-up approaches, and\nsuggest new possibilities for technological applications, e.g., novel\nnon-iridescent structural colors."
    },
    {
        "anchor": "Nematic Tactoid Population: Tactoids are pointed, spindle-like droplets of nematic liquid crystal in an\nisotropic fluid. They have long been observed in inorganic and organic\nnematics, in thermotropic phases as well as lyotropic colloidal aggregates. The\nvariational problem of determining the optimal shape of a nematic droplet is\nformidable and has only been attacked in selected classes of shapes and\ndirector fields. Here, by considering a novel class of admissible solutions for\na bipolar droplet, we study the prevalence in the population of all equilibrium\nshapes of each of the three that may be optimal (tactoids primarily among\nthem). We show how the prevalence of a shape is affected by the drop's volume\n$V_0$ and the saddle-splay constant $K_{24}$ of the material. Tactoids, in\nparticular, prevail for small $V_0$ and small $K_{24}$ (appropriately scaled).\nOur class of shapes (and director fields) is sufficiently different from those\nemployed so far to unveil a rather different role of $K_{24}$.",
        "positive": "Long-range attractive tail of colloid interaction: To describe rich phenomena of dilute dispersions of highly-charged colloid\nparticles, it is necessary to modify the long-range electric part of the DLVO\npotential. The screened Coulomb potential of pure repulsion obtained from the\nHelmholtz free energy in the DLVO theory is replaced by a new screened electric\npotential with long-range attractive tail derived from the generalized Gibbs\nfree energy which is identified with a total sum of chemical potentials."
    },
    {
        "anchor": "How Does A Porous Shell Collapse? Delayed Buckling And Guided Folding Of\n  Inhomogeneous Capsules: Colloidal capsules can sustain an external osmotic pressure; however, for a\nsufficiently large pressure, they will ultimately buckle. This process can be\nstrongly influenced by structural inhomogeneities in the capsule shells. We\nexplore how the time delay before the onset of buckling decreases as the shells\nare made more inhomogeneous; this behavior can be quantitatively understood by\ncoupling shell theory with Darcy's law. In addition, we show that the shell\ninhomogeneity can dramatically change the folding pathway taken by a capsule\nafter it buckles.",
        "positive": "Force distributions in three dimensional compressible granular packs: We present an experimental investigation of the probability distribution of\nnormal contact forces, $P(F)$, at the bottom boundary of static three\ndimensional packings of compressible granular materials. We find that the\ndegree of deformation of individual grains plays a large role in determining\nthe form of this distribution. For small amounts of deformation we find a small\npeak in $P(F)$ below the mean force with an exponential tail for forces larger\nthan the mean force. As the degree of deformation is increased the peak at the\nmean force grows in height and the slope of the exponential tail increases."
    },
    {
        "anchor": "Influence of ionic conditions on knotting in a coarse-grained model for\n  DNA: We investigate knotting probabilities of long double-stranded DNA strands in\na coarse-grained Kratky-Porod model for DNA with Monte Carlo simulations.\nVarious ionic conditions are implemented by adjusting the effective diameter of\nmonomers. We find that the occurrence of knots in DNA can be reinforced\nconsiderably by high salt conditions and confinement between plates. Likewise,\nknots can almost be dissolved completely in a low salt scenario. Comparisons\nwith recent experiments confirm that the coarse-grained model is able to\ncapture and quantitatively predict topological features of DNA and can be used\nfor guiding future experiments on DNA knots.",
        "positive": "Avalanche dynamics in sheared athermal particle packings occurs via\n  localized bursts predicted by unstable linear response: Under applied shear strain, granular and amorphous materials deform via\nparticle rearrangements, which can be small and localized or organized into\nsystem-spanning avalanches. While the statistical properties of avalanches\nunder quasi-static shear are well-studied, the dynamics during avalanches is\nnot. In numerical simulations of sheared soft spheres, we find that avalanches\ncan be decomposed into bursts of localized deformations, which we identify\nusing an extension of persistent homology methods. We also study the linear\nresponse of unstable systems during an avalanche, demonstrating that eigenvalue\ndynamics are highly complex during such events, and that the most unstable\neigenvector is a poor predictor of avalanche dynamics. Instead, we modify\nexisting tools that identify localized excitations in stable systems, and apply\nthem to these unstable systems with non-positive definite Hessians, quantifying\nthe evolution of such excitations during avalanches. We find that bursts of\nlocalized deformations in the avalanche almost always occur at localized\nexcitations identified using the linear spectrum. These new tools will provide\nan improved framework for validating and extending mesoscale elastoplastic\nmodels that are commonly used to explain avalanche statistics in glasses and\ngranular matter."
    },
    {
        "anchor": "Intermittent flow and transient congestions of soft spheres passing\n  narrow orifices: Soft, low-friction particles in silos show peculiar features during their\ndischarge. The outflow velocity and the clogging probability both depend upon\nthe momentary silo fill height, in sharp contrast to silos filled with hard\nparticles. The reason is the fill-height dependence of the pressure at the\norifice. We study the statistics of silo discharge of soft hydrogel spheres.\nThe outflow is found to become increasingly fluctuating and even intermittent\nwith decreasing orifice size, and with decreasing fill height. In orifices\nnarrower than two particle diameters, outflow can stop completely, but in\ncontrast to clogs formed by rigid particles, these congestions may dissolve\nspontaneously. We analyze such non-permanent congestions and attribute them to\nslow reorganization processes in the container, caused by viscoelasticity of\nthe material.",
        "positive": "Programmable Filaments and Textiles: We analyze the various morphing structures obtained by actuating Janus\nfilaments comprising driven and passive sectors and textiles incorporating\ndriven and passive filaments. Transitions between alternative shapes and\ncoexistence of absolutely stable and metastable states within a certain range\nof relative extension upon actuation are detected both in Janus rings and\ntextiles. Both single filaments and textiles can be reverse designed to bend\ninto desired shapes by controlling both the size and orientation of driven\nsectors."
    },
    {
        "anchor": "Steady state particle distribution of a dilute sedimenting suspension: Sedimentation of a non-Brownian suspension of hard particles is studied. It\nis shown that in the low concentration limit a two-particle distribution\nfunction ensuring finite particle correlation length can be found and\nexplicitly calculated. The sedimentation coefficient is computed. Results are\ncompared with experiment.",
        "positive": "Microrheology to Probe Smectic Clusters in Bent-core Nematic Liquid\n  Crystals: Many bent-core nematic liquid crystals exhibit unusual physical properties\ndue to the presence of smectic clusters, known as \"cybotactic\" clusters in the\nnematic phase. Effect of these clusters on complex shear modulus\n($G^*(\\omega)$) of such liquid crystals hitherto unexplored. Here, we study\nflow viscosities and complex shear modulus of two asymmetric bent-core liquid\ncrystals using microrheology technique. The results are corroborated with the\nmeasurements of curvature elastic constants. Compound with shorter hydrocarbon\nchain (8OCH$_\\text{3}$) exhibit only nematic (N) phase whereas the compound\nwith longer chain (16OCH$_\\text{3}$) exhibits both nematic (N) and smectic-A\n(SmA) phases. Our results show that the directional shear modulus of\n16OCH$_\\text{3}$, just above the SmA to N transition temperature is strikingly\ndifferent than 8OCH$_\\text{3}$, owing to these smectic clusters. Thus,\nmicrorheology enables us to probe smectic clusters in bent-core nematic liquid\ncrystals."
    },
    {
        "anchor": "Leaky Membrane Dynamics: A concentration difference of particles across a membrane perforated by pores\nwill induce a diffusive flux. If the diffusing objects are of the same length\nscale as the the pores, diffusion may not be simple, objects can move into the\npore in a configuration that requires them to back up in order to continue\nforward. A configuration that blocks flow through the pore may be statistically\npreferred, an attracting metastable state of the system. This effect is purely\nkinetic, and not dependent on potentials, friction or dissipation. We discuss\nseveral geometries which generate this effect, and introduce a heuristic model\nwhich captures the qualitative features.",
        "positive": "Liquid Polymorphism and Double Criticality in a Lattice Gas Model: We analyze the possible phase diagrams of a simple model for an associating\nliquid proposed previously. Our two-dimensional lattice model combines\noreintati onal ice-like interactions and \\\"{}Van der Waals\\\"{} interactions\nwhich may be repulsive, and in this case represent a penalty for distortion of\nhydrogen bonds in the presence of extra molecules. These interactions can be\ninterpreted in terms of two competing distances, but not necessarily soft-core.\nWe present mean -field calculations and an exhaustive simulation study for\ndifferent parameters which represent relative strength of the bonding\ninteraction to the energy penalty for its distortion. As this ratio decreases,\na smooth disappearance of the doubl e criticality occurs. Possible connections\nto liquid-liquid transitions of molecul ar liquids are suggested."
    },
    {
        "anchor": "Stable thermophoretic trapping of generic particles at low pressures: We demonstrate levitation and three-dimensionally stable trapping of a wide\nvariety of particles in a vacuum chamber through the use of the thermophoretic\nforce in the presence of a strong temperature gradient. Typical sizes of the\ntrapped particles are between 10 microns and 1 mm at a pressure between 1 and\n10 Torr. The trapping stability is provided by the geometry of the temperature\nfield, as well as the transition between the free molecule and hydrodynamic\nregimes of the thermophoretic force. To quantitatively measure the\nthermophoretic force, we examine the levitation heights of spherical\npolyethylene spheres under various experimental conditions and determine the\ntemperature gradient needed to levitate the particles. A good agreement between\nour experimental observations and theoretical calculations is obtained. Our\nsystem offers a new platform to study thermophoretic phenomena and to simulate\ndynamics of interacting many-body systems in a microgravity environment.",
        "positive": "Gel to glass transition in simulation of a valence-limited colloidal\n  system: We numerically study a simple model for thermo-reversible colloidal gelation\nin which particles can form reversible bonds with a predefined maximum number\nof neighbors. We focus on three and four maximally coordinated particles, since\nin these two cases the low valency makes it possible to probe, in equilibrium,\nslow dynamics down to very low temperatures $T$. By studying a large region of\n$T$ and packing fraction $\\phi$ we are able to estimate both the location of\nthe liquid-gas phase separation spinodal and the locus of dynamic arrest, where\nthe system is trapped in a disordered non-ergodic state. We find that there are\ntwo distinct arrest lines for the system: a {\\it glass} line at high packing\nfraction, and a {\\it gel} line at low $\\phi$ and $T$. The former is rather\nvertical ($\\phi$-controlled), while the latter is rather horizontal\n($T$-controlled) in the $(\\phi-T)$ plane. Dynamics on approaching the glass\nline along isotherms exhibit a power-law dependence on $\\phi$, while dynamics\nalong isochores follow an activated (Arrhenius) dependence. The gel has clearly\ndistinct properties from those of both a repulsive and an attractive glass. A\ngel to glass crossover occurs in a fairly narrow range in $\\phi$ along low $T$\nisotherms, seen most strikingly in the behavior of the non-ergodicity factor.\nInterestingly, we detect the presence of anomalous dynamics, such as\nsubdiffusive behavior for the mean squared displacement and logarithmic decay\nfor the density correlation functions in the region where the gel dynamics\ninterferes with the glass dynamics."
    },
    {
        "anchor": "The Statistical Mechanics of Membranes: The fluctuations of two-dimensional extended objects membranes is a rich and\nexciting field with many solid results and a wide range of open issues. We\nreview the distinct universality classes of membranes, determined by the local\norder, and the associated phase diagrams. After a discussion of several\nphysical examples of membranes we turn to the physics of crystalline (or\npolymerized) membranes in which the individual monomers are rigidly bound. We\ndiscuss the phase diagram with particular attention to the dependence on the\ndegree of self-avoidance and anisotropy. In each case we review and discuss\nanalytic, numerical and experimental predictions of critical exponents and\nother key observables. Particular emphasis is given to the results obtained\nfrom the renormalization group epsilon-expansion. The resulting renormalization\ngroup flows and fixed points are illustrated graphically. The full technical\ndetails necessary to perform actual calculations are presented in the\nAppendices. We then turn to a discussion of the role of topological defects\nwhose liberation leads to the hexatic and fluid universality classes. We finish\nwith conclusions and a discussion of promising open directions for the future.",
        "positive": "Lateral diffusion on a frozen random surface: The lateral diffusion coefficient of a Brownian particle on a two-dimensional\nrandom surface is studied in the quenched limit for which the surface\nconfiguration is time-independent. We start with the stochastic equation of\nmotion for a Brownian particle on a fluctuating surface, which has been derived\nby Naji and Brown. The mean square displacement of the particle projected on a\nbase plane is calculated exactly under the condition that the surface with a\nconstant shape has no spatial correlation. We prove that the obtained lateral\ndiffusion coefficient is in between the known upper and lower bounds."
    },
    {
        "anchor": "Solvent control of crack dynamics in a reversible hydrogel: The resistance to fracture of reversible biopolymer hydrogels is an important\ncontrol factor of the cutting/slicing and eating characteristics of food gels.\nIt is also critical for their utilization in tissue engineering, for which\nmechanical protection of encapsulated components is needed. Its dependence on\nloading rate and, recently, on the density and strength of cross-links has been\ninvestigated. But no attention was paid so far to solvent nor to environment\neffects. Here we report a systematic study of crack dynamics in gels of gelatin\nin water/glycerol mixtures. We show on this model system that: (i) increasing\nsolvent viscosity slows down cracks; (ii) soaking with solvent increases\nmarkedly gel fragility; (iii) tuning the viscosity of the (miscible)\nenvironmental liquid affects crack propagation via diffusive invasion of the\ncrack tip vicinity. The results point toward the fact that fracture occurs by\nviscoplastic chain pull-out. This mechanism, as well as the related\nphenomenology, should be common to all reversibly cross-linked (physical) gels.",
        "positive": "Unraveling the success and failure of mode coupling theory from\n  consideration of entropy: We analyze the dynamics of model supercooled liquids in a temperature regime\nwhere predictions of mode coupling theory (MCT) are known to be valid\nqualitatively. In this regime, the Adam-Gibbs (AG) relation, based on an\nactivation picture of dynamics also describes the dynamics satisfactorily, and\nwe explore the mutual consistency and interrelation of these descriptions.\nAlthough entropy and dynamics are related via phenomenological theories, the\nconnection between MCT and entropy has not been argued for. In this work we\nexplore this connection and provide a microscopic derivation of the\nphenomenological Rosenfeld theory. At low temperatures the overlap between MCT\npower law regime and AG relation implies that the AG relation predicts an\navoided divergence at $T_c$, the origin of which is traced back to the\nvanishing of pair configurational entropy, which we find occurs at the same\ntemperature. We also show that the residual multiparticle entropy plays an\nimportant role in describing the relaxation time"
    },
    {
        "anchor": "Nonlinear force balance at moving contact lines: The spreading of a liquid over a solid material is a key process in a wide\nrange of applications. While this phenomenon is well understood when the solid\nis undeformable, its \"soft\" counterpart is still ill-understood and no\nconsensus has been reached with regards to the physical mechanisms ruling the\nspreading of liquid drops over soft deformable materials. In this work we show\nthat the motion of a triple line on a soft elastomer is opposed both by\nnonlinear localized capillary and visco-elastic forces. We give an explicit\nanalytic formula relating the dynamic contact angle of a moving drop with its\nvelocity for arbitrary rheology. We then specialize this formula to the\nexperimentally relevant case of elastomers with Chasset-Thirion (power-law)\ntype of rheologies. The theoretical prediction are in very good agreement with\nexperimental data, without any adjustable parameters. Finally, we show that the\nnonlinear force balance presented in this work can also be used to recover the\nclassical de Gennes model of wetting.",
        "positive": "The isotropic-nematic interface in suspensions of hard rods: Mean-field\n  properties and capillary waves: We present a study of the isotropic-nematic interface in a system of hard\nspherocylinders. First we compare results from Monte Carlo simulations and\nOnsager density functional theory for the interfacial profiles of the\norientational order parameter and the density. Those interfacial properties\nthat are not affected by capillary waves are in good agreement, despite the\nfact that Onsager theory overestimates the coexistence densities. Then we show\nresults of a Monte Carlo study of the capillary waves of the interface. In\nagreement with recent theoretical investigations (Eur.Phys.J. E {\\bf 18} 407\n(2005)) we find a strongly anistropic capillary wave spectrum. For the\nwave-numbers accessed in our simulations, the spectrum is quadratic,\ni.e.elasticity does not play a role. We conjecture that this effect is due to\nthe strong bending rigidity of the director field in suspensions of\nspherocylinders."
    },
    {
        "anchor": "Bubble Raft Model for a Paraboloidal Crystal: We investigate crystalline order on a two-dimensional paraboloid of\nrevolution by assembling a single layer of millimeter-sized soap bubbles on the\nsurface of a rotating liquid, thus extending the classic work of Bragg and Nye\non planar soap bubble rafts. Topological constraints require crystalline\nconfigurations to contain a certain minimum number of topological defects such\nas disclinations or grain boundary scars whose structure is analyzed as a\nfunction of the aspect ratio of the paraboloid. We find the defect structure to\nagree with theoretical predictions and propose a mechanism for scar nucleation\nin the presence of large Gaussian curvature.",
        "positive": "Modeling non-linear dielectric susceptibilities of supercooled molecular\n  liquids: Advances in high-precision dielectric spectroscopy has enabled access to\nnon-linear susceptibilities of polar molecular liquids. The observed\nnon-monotonic behavior has been claimed to provide strong support for theories\nof dynamic arrest based on thermodynamic amorphous order. Here we approach this\nquestion from the perspective of dynamic facilitation, an alternative view\nfocusing on emergent kinetic constraints underlying the dynamic arrest of a\nliquid approaching its glass transition. We derive explicit expressions for the\nfrequency-dependent higher-order dielectric susceptibilities exhibiting a\nnon-monotonic shape, the height of which increases as temperature is lowered.\nWe demonstrate excellent agreement with the experimental data for glycerol,\nchallenging the idea that non-linear response functions reveal correlated\nrelaxation in supercooled liquids."
    },
    {
        "anchor": "Nanoscale creep mechanism of clay through MD modeling with hexagonal\n  particles: In this article, we investigate the creep mechanism of clay at the nanoscale.\nWe conduct the molecular dynamics (MD) modeling of clay samples consisting of\nhexagonal particles under compression and shear. The MD simulations include\noedometer creep, shear creep, direct shear tests, and stress relaxation. The\nnumerical results show that the nanoscale creep mechanism of clay is related to\nparticle rotation, translation, and stacking under different loading\nconditions. The clay sample under creep shows two types of particle\narrangements, i.e., the shifted face-to-face configuration and the face-to-edge\nconfiguration. The orientation angle of clay particles is computed to track the\nrotation of individual particles due to creep. The fabric variation of the clay\nunder creep is characterized by the dihedral angle between the basal particle\nplane and the x-y plane and the order parameter. It is found that the factors\naffecting the microstructure variation of the clay aggregate include stress\nlevels, loading rates, and particle sizes. In the nanoscale shear creep test,\nthe creep process comprises three stages, i.e., primary, secondary, and\ntertiary. The microstructure change during creep depends on the initial\nalignment of clay particles. The clay creep under a more significant stress\nlevel results in a more considerable order parameter and a more orientated clay\nstructure.",
        "positive": "Onsager-Manning-Oosawa condensation phenomenon and the effect of salt: Making use of results pertaining to Painleve III type equations, we revisit\nthe celebrated Onsager-Manning-Oosawa condensation phenomenon for charged stiff\nlinear polymers, in the mean-field approximation with salt. We obtain\nanalytically the associated critical line charge density, and show that it is\nseverely affected by finite salt effects, whereas previous results focused on\nthe no salt limit. In addition, we obtain explicit expressions for the\ncondensate thickness and the electric potential. The case of asymmetric\nelectrolytes is also briefly addressed."
    },
    {
        "anchor": "Colloidal Lattice Shearing and Rupturing with a Driven Line of Particles: We examine the dynamics of two-dimensional colloidal systems using numerical\nsimulations of a system with a drive applied to a thin region in the middle of\nthe sample to produce a local shear. For a monodisperse colloidal assembly, we\nfind a well defined decoupling transition separating a regime of elastic motion\nfrom a plastic phase where the particles in the driven region break away or\ndecouple from the particles in the bulk, producing a shear band. For a\nbidisperse assembly, we find that the onset of a bulk disordering transition\ncoincides with the broadening of the shear band. We identify several distinct\ndynamical regimes that are correlated with features in the velocity-force\ncurves. As a function of bidispersity, the decoupling force shows a\nnonmonotonic behavior associated with features in the noise fluctuations, power\nspectra, and bulk velocity profiles. When pinning is added in the bulk, we find\nthat the shear band regions can become more localized, causing a decoupling of\nthe driven particles from the bulk particles. For a system with thermal noise\nand no pinning, the shear band region becomes more extended and the average\nvelocity of the driven particles drops at the thermal disordering transition of\nthe bulk system.",
        "positive": "Simulating the interaction between a falling super-quadric object and a\n  soap film: The interaction that occurs between a light solid object and a horizontal\nsoap film of a bamboo foam contained in a cylindrical tube is simulated in 3D.\nWe vary the shape of the falling object from a sphere to a cube by changing a\nsingle shape parameter as well as varying the initial orientation and position\nof the object. We investigate in detail how the soap film deforms in all these\ncases, and determine the network and pressure forces that a foam exerts on a\nfalling object, due to surface tension and bubble pressure respectively. We\nshow that a cubic particle in a particular orientation experiences the largest\ndrag force, and that this orientation is also the most likely outcome of\ndropping a cube from an arbitrary orientation through a bamboo foam."
    },
    {
        "anchor": "The mechanical influence of single fibre inclusions in discrete fibre\n  networks: Semiflexible biopolymer networks are commonly found in biological systems,\nfrom the cytoskeleton of cells to the extracellular matrix. Such networks often\nnaturally occur as composites, in which various components interact to generate\nrich mechanical behaviours. In this work we examine the mechanics of composites\nformed when a single fibre inclusion is placed within discrete fibre networks\nof two distinct architectures. In particular, we computationally and\ntheoretically investigate the mechanics of composites formed when an inclusion\nis introduced to Voronoi- and Mikado--type networks within the nonaffine\nregime. On subjecting these single inclusion composites to small shear\ndeformations, we observe different behaviours dependent on the choice of\nnetwork geometry. This divergence in mechanical responses is interpreted as a\nconsequence of architecture-dependent differences in the nonaffine displacement\nfield. Scaling laws for the increase in network energy due to inclusions of\ndifferent lengths, orientations, and elastic properties are proposed and\ncomputationally verified. We present theoretical predictions for critical\nvalues of the inclusion bending and stretching stiffnesses, above which no\nfurther increases in network energy are observed for a given shear deformation.\nThese predictions are supported by extensive computational evidence. We expect\nthe architectural differences identified in this work to be pertinent to\ntheoretical investigations into the complex behaviour of biopolymer networks,\nand to experimental work, where complex mechanics has been observed in\ncomposite fibre networks.",
        "positive": "Extending the Maier-Saupe theory to cybotactic nematics: A theory of thermotropic nematic liquid crystals in which molecules form\ninternally ordered clusters is presented. The formulation is based on the same\nmean field approximation and form of the anisotropic potential used in the\nMaier-Saupe theory. A uniaxial nematic and two macroscopically isotropic phases\nare predicted. One of the isotropic phases consists of thermodynamically stable\nclusters with internal orientational order. The nematic phase shows cybotactic\norder throughout its range of stability. This order persists above the\ntransition temperature, either as a stable feature or as a pretransitional\neffect. The values of the order parameter and of the entropy change at the\nnematic to isotropic phase transition depend on the size of the clusters. The\nMaier-Saupe theory is obtained in the limit of extremely large or extremely\nsmall clusters."
    },
    {
        "anchor": "Universal scaling of active nematic turbulence: A landmark of turbulence is the emergence of universal scaling laws, such as\nKolmogorov's $E(q)\\sim q^{-5/3}$ scaling of the kinetic energy spectrum of\ninertial turbulence with the wave vector $q$. In recent years, active fluids\nhave been shown to exhibit turbulent-like flows at low Reynolds number.\nHowever, the existence of universal scaling properties in these flows has\nremained unclear. To address this issue, here we propose a minimal defect-free\nhydrodynamic theory for two-dimensional active nematic fluids at vanishing\nReynolds number. By means of large-scale simulations and analytical arguments,\nwe show that the kinetic energy spectrum exhibits a universal scaling $E(q)\\sim\nq^{-1}$ at long wavelengths. We find that the energy injection due to activity\nhas a peak at a characteristic length scale, which is selected by a nonlinear\nmechanism. In contrast to inertial turbulence, energy is entirely dissipated at\nthe scale where it is injected, thus precluding energy cascades. Nevertheless,\nthe non-local character of the Stokes flow establishes long-ranged velocity\ncorrelations, which lead to the scaling behavior. We conclude that active\nnematic fluids define a distinct universality class of turbulence at low\nReynolds number.",
        "positive": "Maximally mixing active nematics: Active nematics are an important new paradigm in soft condensed matter\nsystems. They consist of rod-like components with an internal driving force\npushing them out of equilibrium. The resulting fluid motion exhibits chaotic\nadvection, in which a small patch of fluid is stretched exponentially in\nlength. Using simulation, this Letter shows that this system can exhibit stable\nperiodic motion when sufficiently confined to a square with periodic boundary\nconditions. Moreover, employing tools from braid theory, we show that this\nmotion is maximally mixing, in that it optimizes the (dimensionless)\n``topological entropy'' -- the exponential stretching rate of a material line\nadvected by the fluid. That is, this periodic motion of the defects,\ncounterintuitively, produces more chaotic mixing than chaotic motion of the\ndefects. We also explore the stability of the periodic state. Importantly, we\nshow how to stabilize this orbit into a larger periodic tiling, a critical\nnecessity for it to be seen in future experiments."
    },
    {
        "anchor": "Defect patterns of two-dimensional nematic liquid crystals in\n  confinement: A two-dimensional or quasi-two-dimensional nematic liquid crystal refers to a\nsurface confined system. When such a system is further confined by external\nline boundaries or excluded from internal line boundaries, the nematic\ndirectors form a deformed texture that may display defect points or defect\nlines, for which winding numbers can be clearly defined. Here, a particular\nattention is paid to the case when the liquid crystal molecules prefer to form\na boundary nematic texture in parallel to the wall surface (i.e., following the\nhomogeneous boundary condition). A general theory, based on geometric argument,\nis presented for the relationship between the sum of all winding numbers in the\nsystem (the total winding number) and the type of confinement angles and curved\nsegments. The conclusion is validated by comparing the theoretical defect rule\nwith existing nematic textures observed experimentally and theoretically in\nrecent years.",
        "positive": "Toward predicting tensile strength of pharmaceutical tablets by\n  ultrasound measurement in continuous manufacturing: An ultrasound measurement system was employed as a non-destructive method to\nevaluate its reliability in predicting the tensile strength of tablets and\ninvestigate the benefits of incorporating it in a continuous line,\nmanufacturing solid dosage forms. Tablets containing lactose, acetaminophen,\nand magnesium stearate were manufactured continuously and in batches. The\neffect of two processing parameters, compaction force and level of shear strain\nwere examined. Young's modulus and tensile strength of tablets were obtained by\nultrasound and diametrical mechanical testing, respectively. It was found that\nas the blend was exposed to increasing levels of shear strain, the speed of\nsound in the tablets decreased and the tablets became both softer and\nmechanically weaker. Moreover, the results indicate that two separate tablet\nmaterial properties (e.g., relative density and Young's modulus) are necessary\nin order to predict tensile strength. A strategy for hardness prediction is\nproposed that uses the existing models for Young's modulus and tensile strength\nof porous materials. Ultrasound testing was found to be very sensitive in\ndifferentiating tablets with similar formulation but produced under different\nprocessing conditions (e.g., different level of shear strain), thus, providing\na fast, and non-destructive method for hardness prediction that could be\nincorporated to a continuous manufacturing process."
    },
    {
        "anchor": "Percolation and Reynolds flow in elastic contacts of isotropic and\n  anisotropic, randomly rough surface: In this work, we numerically study the elastic contact between isotropic and\nanisotropic, rigid, randomly rough surfaces and linearly elastic counterfaces\nas well as the subsequent Reynolds flow through the gap between the two\ncontacting solids. We find the percolation threshold to depend on the\nfluid-flow direction when the Peklenik number indicates anisotropy unless the\nsystem size clearly exceeds the roll-off wave length parallel to the easy flow\ndirection. A critical contact area near 0.415 is confirmed. Heuristically\ncorrected effective-medium treatments satisfactorily provide Reynolds\nfluid-flow conductances, e.g., for isotropic roughness, we identify accurate\nclosed-form expressions, which only depend on the mean gap and the relative\ncontact area.",
        "positive": "Surface plasmon resonance for in-plane birefringence measurement of\n  anisotropic thin organic film: The measurement of in-plane birefringence ($\\Delta{n}$) of ultrathin film is\nchallenging due to a significant deviation of physical properties of materials\nin ultrathin regime as compared to that in bulk state. Surface plasmon\nresonance (SPR) phenomenon can be employed to measure change in refractive\nindex of ultrathin film at a very high resolution. This article discusses\nsimulation of SPR phenomenon in Kretschmann configuration for the measurement\nof $\\Delta{n}$ in organic thin film exhibiting nematic-like ordering on the two\ndimensional gold surface. The distribution of plasmonic field on the gold\nsurface was found to be anisotropic. This suggested that the coupling plasmonic\nfield with that of organic thin film exhibiting nematic-like ordering on the\ngold surface will be non-isotropic. Therefore, a non-zero difference in\nresonance angle (RA) was obtained from SPR measurement performed along the\noptic-axis (OA) and orthogonal to OA of the in-plane nematic ordering\n($\\Delta\\theta$). A calibration surface showing the variation of\n($\\Delta\\theta$) as a function of $\\Delta{n}$ and thickness of thin organic\nfilm consisting of shape anisotropic tilted molecules exhibiting nematic-like\nordering on gold surface was obtained. This calibration surface was employed\nfor the measurement of $\\Delta{n}$ of single layer of Langmuir-Blodgett films\nof cadmium stearate (CdSA) and 4'-octyl-4-biphenylcarbonitrile (8CB) deposited\non SPR chips. The thickness of the LB films was estimated using X-ray\nreflectivity measurement and $\\Delta\\theta$ was measured using a home built SPR\ninstrument. The $\\Delta{n}$ values were found to be 0.012 and 0.022 for\nultrathin films of CdSA and 8CB molecules, respectively."
    },
    {
        "anchor": "Active nematic-isotropic interfaces on flat surfaces: effects of\n  anchoring, ordering field and activity: A surface in contact with the isotropic phase of a passive liquid crystal can\ninduce nematic order over distances that range from microscopic to macroscopic\nwhen the nematic-isotropic interface undergoes an orientational-wetting\ntransition. If the nematic is active, what happens to the interface? Does it\npropagate and, if it does, is its structure different from the passive one? In\nthis paper, we address these questions. We investigate how the active\nnematic-isotropic interface is affected by the anchoring strength of the\nsurface, the bulk ordering field and the activity. We find that while passive\ninterfaces are one-dimensional the active ones exhibit two dynamical regimes: a\npassive-like regime and a propagating regime where the interfaces propagate\nuntil the entire domain is active nematic. Active interfaces break the\ntranslational symmetry within the interfacial plane above a threshold activity,\nwhere the active nematic fluctuations, which are ultimately responsible for the\nemergence of an active turbulent nematic phase, drive non-steady dynamical\ninterfacial regimes.",
        "positive": "Separation of plastic deformations in polymers based on elements of\n  general nonlinear theory: We report a method for describing plasticity in a broad class of amorphous\nmaterials. The method is based on nonlinear (geometric) deformation theory\nallowing the separation of the plastic deformation from the general deformation\ntensor. This separation allows an adequate pattern of thermodynamical phenomena\nfor plastic deformations in polymers to be constructed. A parameter describing\nthe stress relaxation rate of the material is introduced within the frame of\nthis approach. Additionally, several experimental configurations to measure\nthis parameter are discussed."
    },
    {
        "anchor": "Feedback control of colloidal transport: We review recent work on feedback control of one-dimensional colloidal\nsystems, both with instantaneous feedback and with time delay. The feedback\nschemes are based on measurement of the average particle position, a natural\ncontrol target for an ensemble of colloidal particles, and the systems are\ninvestigated via the Fokker-Planck equation for overdamped Brownian particles.\nTopics include the reversal of current and the emergence of current\noscillations, transport in ratchet systems, and the enhancement of mobility by\na co-moving trap. Beyond the commonly considered case of non-interacting\nsystems, we also discuss the treatment of colloidal interactions via\n(dynamical) density functional theory and provide new results for systems with\nattractive interactions.",
        "positive": "Dipoles in thin sheets: A flat elastic sheet may contain pointlike conical singularities that carry a\nmetrical \"charge\" of Gaussian curvature. Adding such elementary defects to a\nsheet allows one to make many shapes, in a manner broadly analogous to the\nfamiliar multipole construction in electrostatics. However, here the underlying\nfield theory is non-linear, and superposition of intrinsic defects is\nnon-trivial as it must respect the immersion of the resulting surface in three\ndimensions. We consider a \"charge-neutral\" dipole composed of two conical\nsingularities of opposite sign. Unlike the relatively simple electrostatic\ncase, here there are two distinct stable minima and an infinity of unstable\nequilibria. We determine the shapes of the minima and evaluate their energies\nin the thin-sheet regime where bending dominates over stretching. Our\npredictions are in surprisingly good agreement with experiments on paper\nsheets."
    },
    {
        "anchor": "Collapse dynamics of copolymers in a poor solvent: Influence of\n  hydrodynamic interactions and chain sequence: We investigate the dynamics of the collapse of a single copolymer chain, when\nthe solvent quality is suddenly quenched from good to poor. We employ Brownian\ndynamics simulations of a bead-spring chain model and incorporate fluctuating\nhydrodynamic interactions via the Rotne-Prager-Yamakawa tensor. Various\ncopolymer architectures are studied within the framework of a two-letter HP\nmodel, where monomers of type H (hydrophobic) attract each other, while all\ninteractions involving P (polar or hydrophilic) monomers are purely repulsive.\nThe hydrodynamic interactions are found to assist the collapse. Furthermore,\nthe chain sequence has a strong influence on the kinetics and on the\ncompactness and energy of the final state. The dynamics is typically\ncharacterised by initial rapid cluster formation, followed by coalescence and\nfinal rearrangement to form the compact globule. The coalescence stage takes\nmost of the collapse time, and its duration is particularly sensitive to the\ndetails of the architecture. Long blocks of type P are identified as the main\nbottlenecks to find the globular state rapidly.",
        "positive": "Exploiting imperfections: Directed assembly of surface colloids via bulk\n  topological defects: We exploit the long-ranged elastic fields inherent to confined nematic liquid\ncrystals to assemble colloidal particles trapped at the liquid crystal\ninterface into reconfigurable structures with complex symmetries and packings.\nSpherical colloids with homeotropic anchoring trapped at the interface between\nair and the nematic liquid crystal 5CB create quadrupolar distortions in the\ndirector field causing particles to repel and consequently form close-packed\nassemblies with a triangular habit. Here we report on complex, open structures\norganized via interactions with defects in the bulk. Specifically, by confining\nthe nematic liquid crystal in an array of microposts with homeotropic anchoring\nconditions, we cause defect rings to form at well-defined locations in the bulk\nof the sample. These defects source elastic deformations that direct the\nassembly of the interfacially-trapped colloids into ring-like assemblies, which\nrecapitulate the defect geometry even when the microposts are completely\nimmersed in the nematic. When the surface density of the colloids is high, they\nform a ring near the defect and a hexagonal lattice far from it. Since\ntopographically complex substrates are easily fabricated and liquid crystal\ndefects are readily reconfigured, this work lays the foundation for a new,\nrobust mechanism to dynamically direct assembly over large areas by controlling\nsurface anchoring and associated bulk defect structure."
    },
    {
        "anchor": "Pressure screening and fluctuations at the bottom of a granular column: We report sets of precise and reproducible measurements on the static\npressure at the bottom of a granular column. We make a quantitative analysis of\nthe pressure saturation when the column height is increased. We evidence a\ngreat sensitivity of the measurements with the global packing fraction and the\neventual presence of shear bands at the boundaries. We also show the limit of\nthe classical Janssen model and discuss these experimental results under the\nscope of recently proposed theoretical frameworks.",
        "positive": "A generalized mechanical model using stress-strain duality at large\n  strain for amorphous polymers: Numerous models have been developed in the literature to simulate the\nthermomechanical behavior of amorphous polymer at large strain. These models\ngenerally show a good agreement with experimental results when the material is\nsubmitted to uniaxial loadings (tension or compression) or in case of shear\nloadings. However, this agreement is highly degraded when they are used in the\ncase of combined load cases. A generalization of these models to more complex\nloads is scarce. In particular, models that are identified in tension or\ncompression often overestimate the response in shear. One difficulty lies in\nthe fact that 3D models must aggregate different physical modeling, described\nwith different kinematics. This requires the use of transport operators complex\nto manipulate. In this paper, we propose a mechanical model for large strains,\ngeneralized in 3D, and precisely introducing the adequate transport operators\nin order to obtain an exact kinematic. The stress strain duality is validated\nin the writing of the power of internal forces. This generalized model is\napplied in the case of a polycarbonate amorphous polymers. The simulation\nresults in tension/compression and shear are compared with the classical\nmodeling and experimental results from the literature. The results highly\nimprove the numerical predictions of the mechanical response of amorphous\npolymers submitted to any load case."
    },
    {
        "anchor": "Geometrically-protected reversibility in hydrodynamic Loschmidt-echo\n  experiments: We demonstrate an archetypal Loschmidt-echo experiment involving thousands of\ndroplets which interact in a reversible fashion via a viscous fluid. Firstly,\nwe show that, unlike equilibrium systems, periodically driven microfluidic\nemulsions self-organize and geometrically protect their macroscopic\nreversibility. Self-organization is not merely dynamical; we show that it has a\nclear structural signature akin to that found in a mixture of molecular\nliquids. Secondly, we show that, above a maximal shaking amplitude, structural\norder and reversibility are lost simultaneously in the form of a first order\nnon-equilibrium phase transition. We account for this discontinuous transition\nin terms of a memory-loss process. Finally, we suggest potential applications\nof microfluidic echo as a robust tool to tailor colloidal self-assembly at\nlarge scales.",
        "positive": "No many-scallop theorem: Collective locomotion of reciprocal swimmers: To achieve propulsion at low Reynolds number, a swimmer must deform in a way\nthat is not invariant under time-reversal symmetry; this result is known as the\nscallop theorem. We show here that there is no many-scallop theorem. We\ndemonstrate that two active particles undergoing reciprocal deformations can\nswim collectively; moreover, polar particles also experience effective\nlong-range interactions. These results are derived for a minimal dimers model,\nand generalized to more complex geometries on the basis of symmetry and scaling\narguments. We explain how such cooperative locomotion can be realized\nexperimentally by shaking a collection of soft particles with a homogeneous\nexternal field."
    },
    {
        "anchor": "A global investigation of phase equilibria using the Perturbed-Chain\n  Statistical-Associating-Fluid-Theory (PC-SAFT) approach: The recently developed Perturbed-Chain Statistical Associating Fluid Theory\n(PC-SAFT) is investigated for a wide range of model parameters including the\nparameter m representing the chain length and the thermodynamic temperature T\nand pressure p. This approach is based upon the first-order thermodynamic\nperturbation theory for chain molecules developed by Wertheim and Chapman et\nal. and includes dispersion interactions via the second-order perturbation\ntheory of Barker and Henderson. We systematically study a hierarchy of models\nwhich are based on the PC-SAFT approach using analytical model calculations and\nMonte Carlo simulations. For one-component systems we find that the analytical\nmodel in contrast to the simulation results exhibits two phase-separation\nregions in addition to the common gas-liquid coexistence region: One phase\nseparation occurs at high density and low temperature. The second demixing\ntakes place at low density and high temperature where usually the ideal gas\nphase is expected in the phase diagram. These phenomena, which are referred to\nas \"liquid-liquid\" and \"gas-gas\" equilibria, give rise to multiple critical\npoints in one-component systems, as well as to critical end points (CEP) and\nequilibria of three fluid phases, which can usually be found in multicomponent\nmixtures only. Furthermore, it is shown that the \"liquid-liquid\" demixing in\nthis model is not a consequence of a \"softened\" repulsive interaction as\nassumed in the theoretical derivation of the model. Experimental data for the\nmelt density of polybutadiene with molecular mass Mw=45000g/mol are correlated\nhere using the PC-SAFT equation. It is shown that the discrepancies in modeling\nthe polymer density at ambient temperature and high pressure can be traced back\nto ...",
        "positive": "Extreme Spontaneous Deformations of Active Crystals: We demonstrate that two-dimensional crystals made of active particles can\nexperience extremely large spontaneous deformations without melting. Using\nparticles mostly interacting via pairwise repulsive forces, we show that such\nactive crystals maintain long-range bond order and algebraically-decaying\npositional order, but with an exponent $\\eta$ not limited by the $\\tfrac{1}{3}$\nbound given by the (equilibrium) KTHNY theory. We rationalize our findings\nusing linear elastic theory and show the existence of two well-defined\neffective temperatures quantifying respectively large-scale deformations and\nbond-order fluctuations. The root of these phenomena lies in the sole\ntime-persistence of the intrinsic axes of particles, and they should thus be\nobserved in many different situations."
    },
    {
        "anchor": "Evaporation of ethanol-water droplet at different substrate temperatures\n  and compositions: We experimentally investigate the evaporation dynamics of sessile droplets of\na fixed volume consisting of different compositions of ethanol-water binary\nmixture at different substrate temperatures (T_s). At T_s=25oC, we observe\npinned-stage linear evaporation for pure droplets, but a binary droplet\nundergoes two distinct evaporation stages: an early pinned stage and a later\nreceding stage. In the binary droplet, the more volatile ethanol, evaporates\nfaster leading to a nonlinear trend in the evaporation process at the early\nstage. The phenomenon observed in the present study at T_s=25oC is similar to\nthat presented by previous researchers at room temperature. More interesting\ndynamics is observed in the evaporation process of a binary droplet at an\nelevated substrate temperature. We found that the lifetime of the droplet\nexhibits a non-monotonic trend with the increase in ethanol concentration in\nthe binary mixture, which {can be attributed to} the non-ideal behaviour of\nwater-ethanol binary mixtures. Increasing T_s decreases the lifetime of the\n(50\\% ethanol + 50 \\% water) binary droplet in a logarithmic scale. For this\ncomposition, at T_s=60oC, we observed an early spreading stage, an intermediate\npinned stage and a late receding stage of evaporation. Unlike T_s=25oC, at the\nearly times of the evaporation process, the contact angle of the droplet of\npure water at T_s=60oC is greater than 90. Late stage interfacial instability\nand even droplet break-up are observed for some (though not all) binary mixture\ncompositions. The evaporation dynamics for different compositions at T_s=60oC\nexhibit a self-similar trend. Finally, the evaporation rates of pure and binary\ndroplets at different substrate temperatures are compared against a theoretical\nmodel developed for pure and binary mixture droplets.",
        "positive": "Mesoscale simulation of semiflexible chains. I. Endpoint distribution\n  and chain dynamics: The endpoint distribution and dynamics of semiflexible fibers is studied by\nnumerical simulation. A brief overview is given over the analytical theory of\nflexible and semiflexible polymers. In particular, a closed expression is given\nfor the relaxation spectrum of wormlike chains, which determines polymer\ndiffusion and rheology. Next a simulation model for wormlike chains with full\nhydrodynamic interaction is described, and relations for the bending and\ntorsion modulus are given. Two methods are introduced to include torsion\nstiffness into the model. The model is validated by simulating single chains in\na heat bath, and comparing the endpoint distribution of the chains with\nestablished Monte Carlo results. It is concluded that torsion stiffness leads\nto a slightly shorter effective persistence length for a given bending\nstiffness. To further validate the simulation model, polymer diffusion is\nstudied for fixed persistence length and varying polymer length N. The\ndiffusion constant shows crossover from Rouse to reptation behaviour. The\nterminal relaxation time obtained from the monomer displacement is consistent\nwith the theory of wormlike chains. The probability for chain crossing has also\nbeen studied. This probability is so low that it does not influence the present\nresults."
    },
    {
        "anchor": "Density and Glass Forming Ability in Amorphous Atomic Alloys: the Role\n  of the Particle Softness: A key property of glass forming alloys, the anomalously small volume\ndifference with respect to the crystal, is shown to arise as a direct\nconsequence of the soft repulsive potentials between metals. This feature of\nthe inter-atomic potential is demonstrated to be responsible for a significant\ncomponent of the glass forming ability of alloys due to the decrease in the\nenthalpy of fusion and the associated depression of the freezing point.",
        "positive": "Effects of crosslinks on motor-mediated filament organization: Crosslinks and molecular motors play an important role in the organization of\ncytoskeletal filament networks. Here we incorporate the effect of crosslinks\ninto our model of polar motor-filament organization [Phys. Rev. E {\\bf 71},\n050901 (2005)], through suppressing the relative sliding of filaments in the\ncourse of motor-mediated alignment. We show that this modification leads to a\nnontrivial macroscopic behavior, namely the oriented state exhibits a\ntransverse instability in contrast to the isotropic instability that occurs\nwithout crosslinks. This transverse instability leads to the formation of dense\nextended bundles of oriented filaments, similar to recently observed structures\nin actomyosin. This model also can be applied to situations with two oppositely\ndirected motor species or motors with different processing speeds."
    },
    {
        "anchor": "Dynamical heterogeneity in a model for permanent gels: Different\n  behavior of dynamical susceptibilities: We present a systematic study of dynamical heterogeneity in a model for\npermanent gels, upon approaching the gelation threshold. We find that the\nfluctuations of the self intermediate scattering function are increasing\nfunctions of time, reaching a plateau whose value, at large length scales,\ncoincides with the mean cluster size and diverges at the percolation threshold.\nAnother measure of dynamical heterogeneities, i.e. the fluctuations of the\nself-overlap, displays instead a peak and decays to zero at long times. The\npeak, however, also scales as the mean cluster size. Arguments are given for\nthis difference in the long time behavior. We also find that non-Gaussian\nparameter reaches a plateau in the long time limit. The value of the plateau of\nthe non-Gaussian parameter, which is connected to the fluctuations of\ndiffusivity of clusters, increases with the volume fraction and remains finite\nat percolation threshold.",
        "positive": "Evidence of Water-related Discrete Trap State Formation in Pentacene\n  Single Crystal Field-Effect Transistors: We report on the generation of a discrete trap state during negative gate\nbias stress in pentacene single crystal \"flip-crystal\" field-effect transistors\nwith a SiO2 gate dielectric. Trap densities of up to 2*10^12 cm^-2 were created\nin the experiments. Trap formation and trap relaxation are distinctly different\nabove and below ~280 K. In devices in which a self-assembled monolayer on top\nof the SiO2 provides a hydrophobic insulator surface we do not observe trap\nformation. These results indicate the microscopic cause of the trap state to be\nwater adsorbed on the SiO2 surface."
    },
    {
        "anchor": "Effect of genome sequence on the force-induced unzipping of a DNA\n  molecule: We considered a dsDNA polymer in which distribution of bases are random at\nthe base pair level but ordered at a length of 18 base pairs and calculated its\nforce elongation behaviour in the constant extension ensemble. The unzipping\nforce $F(y)$ vs. extension $y$ is found to have a series of maxima and minima.\nBy changing base pairs at selected places in the molecule we calculated the\nchange in $F(y)$ curve and found that the change in the value of force is of\nthe order of few pN and the range of the effect depending on the temperature,\ncan spread over several base pairs. We have also discussed briefly how to\ncalculate in the constant force ensemble a pause or a jump in the\nextension-time curve from the knowledge of $F(y)$.",
        "positive": "Spontaneous Self-Constraint in Active Nematic Flows: Active processes drive and guide biological dynamics across scales -- from\nsubcellular cytoskeletal remodelling, through tissue development in\nembryogenesis, to population-level bacterial colonies expansion. In each of\nthese, biological functionality requires collective flows to occur while\nself-organized structures are protected; however, the mechanisms by which\nactive flows can spontaneously constrain their dynamics to preserve structure\nhave not previously been explained. By studying collective flows and defect\ndynamics in active nematic films, we demonstrate the existence of a\nself-constraint -- a two-way, spontaneously arising relationship between\nactivity-driven isosurfaces of flow boundaries and mesoscale nematic\nstructures. Our results show that self-motile defects are tightly constrained\nto viscometric surfaces -- contours along which vorticity and strain-rate\nbalance. This in turn reveals that self-motile defects break mirror symmetry\nwhen they move along a single viscometric surface, in contrast with\nexpectations. This is explained by an interdependence between viscometric\nsurfaces and bend walls -- elongated narrow kinks in the orientation field.\nAlthough we focus on extensile nematic films, numerical results show the\nconstraint holds whenever activity leads to motile half-charge defects. This\nmesoscale cross-field self-constraint offers a new framework for tackling\ncomplex 3D active turbulence, designing dynamic control into biomimetic\nmaterials, and understanding how biological systems can employ active stress\nfor dynamic self-organization."
    },
    {
        "anchor": "Heteropolymer Sequence Design and Preferential Solvation of Hydrophilic\n  Monomers: One More Application of Random Energy Model: In this paper, we study the role of surface of the globule and the role of\ninteractions with the solvent for designed sequence heteropolymers using random\nenergy model (REM). We investigate the ground state energy and surface monomer\ncomposition distribution. By comparing the freezing transition in random and\ndesigned sequence heteropolymers, we discuss the effects of design. Based on\nour results, we are able to show under which conditions solvation effect\nimproves the quality of sequence design. Finally, we study sequence space\nentropy and discuss the number of available sequences as a function of imposed\nrequirements for the design quality.",
        "positive": "Oxygenation-Controlled Collective Dynamics in Aquatic Worm Blobs: Many types of organisms utilize group aggregation as a method for survival.\nThe freshwater oligochaete, California blackworms Lumbriculus variegatus form\ntightly entangled structures, or worm \"blobs\", that have adapted to survive in\nextremely low levels of dissolved oxygen (DO). Individual blackworms adapt to\nhypoxic environments through respiration via their mucous body wall and\nposterior ciliated hindgut, which they wave above them. However, the change in\ncollective behavior at different levels of DO is not known. Using a closed-loop\nrespirometer with flow, we discover that the relative tail reaching activity\nflux in low DO is $\\sim$75x higher than in the high DO condition. Additionally,\nwhen flow rate is increased to suspend the worm blobs upward, we find that the\naverage exposed surface area of a blob in low DO is $\\sim$1.4x higher than in\nhigh DO. Furthermore, we observe emergent properties that arise when a worm\nblob is exposed to extreme DO levels. Here we show that internal stress is\ngenerated when worm blobs are exposed to high DO levels, allowing them to be\nphysically lifted off from the bottom of a conical container using a serrated\nendpiece. Our results demonstrate how both collective behavior and the emergent\ngeneration of internal stress in worm blobs change to accommodate differing\nlevels of oxygen, which could be used to model and simulate swarm robots,\nself-assembly structures, or soft material entanglements."
    },
    {
        "anchor": "Motility induced phase separation of deformable cells: Using a multi-phase field model, we examine how particle deformability, which\nis a proxy for cell stiffness, affects motility induced phase separation\n(MIPS). We show that purely repulsive deformable, i.e., squishy, cells phase\nseparate more effectively than their rigid counterparts. This can be understood\nas due to the fact that deformability increases the effective duration of\ncollisions. In addition, the dense regions become increasingly disordered as\ndeformability increases. Our results contextualize the applicability of MIPS to\nbiological systems and have implications for how cells in biological systems\nmay self-organize",
        "positive": "Deformation and failure maps for PMMA in uniaxial tension: Uniaxial tensile tests are performed on a polymethyl methacrylate (PMMA)\ngrade over a range of temperatures near the glass transition and over two\ndecades of strain rate. Deformation maps are constructed for Young's modulus,\nflow strength, and failure strain as a function of temperature for selected\nstrain rates. The glassy, glass transition and rubbery regimes are identified,\nand constitutive relations are calibrated for the modulus and flow strength\nwithin each regime."
    },
    {
        "anchor": "Hanbury Brown-Twiss Interferometry for Fractional and Integer Mott\n  Phases: Hanbury-Brown-Twiss interferometry (HBTI) is used to study integer and\nfractionally filled Mott Insulator (MI) phases in period-2 optical\nsuperlattices. In contrast to the quasimomentum distribution, this second order\ninterferometry pattern exhibits high contrast fringes in the it insulating\nphases. Our detailed study of HBTI suggests that this interference pattern\nsignals the various superfluid-insulator transitions and therefore can be used\nas a practical method to determine the phase diagram of the system. We find\nthat in the presence of a confining potential the insulating phases become\nrobust as they exist for a finite range of atom numbers. Furthermore, we show\nthat in the trapped case the HBTI interferogram signals the formation of the MI\ndomains and probes the shell structure of the system.",
        "positive": "Hierarchical Self-Assembly of Asymmetric Amphiphatic Spherical Colloidal\n  Particles: From dumbbells to FCC crystals, we study the self-assembly pathway of\namphiphatic, spherical colloidal particles as a function of the size of the\nhydrophobic region using molecular dynamics simulations. Specifically, we\nanalyze how local inter-particle interactions correlate to the final\nself-assembled aggregate and how they affect the dynamical pathway of structure\nformation. We present a detailed diagram separating the many phases that we\nfind for different sizes of the hydrophobic area, and uncover a narrow region\nwhere particles self-assemble into hollow, faceted cages that could potentially\nfind interesting engineering applications."
    },
    {
        "anchor": "Topology in non-linear mechanical systems: Many advancements have been made in the field of topological mechanics. The\nmajority of the works, however, concerns the topological invariant in a linear\ntheory. We, in this work, present a generic prescription of defining\ntopological indices which accommodates non-linear effects in mechanical systems\nwithout taking any approximation. Invoking the tools of differential geometry,\na Z-valued quantity in terms of the Poincare-Hopf index, that features the\ntopological invariant of non-linear zero modes (ZMs), is predicted. We further\nidentify one type of topologically protected solitons that are robust to\ndisorders. Our prescription constitutes a new direction of searching for novel\ntopologically protected non-linear ZMs in the future.",
        "positive": "Finite-size scaling in asymmetric systems of percolating sticks: We investigate finite size scaling in percolating widthless stick systems\nwith variable aspect ratios in an extensive Monte Carlo simulation study. A\ngeneralized scaling function is introduced to describe the scaling behavior of\nthe percolation distribution moments and probability at the percolation\nthreshold. We show that the prefactors in the generalized scaling function\ndepend on the system aspect ratio and exhibit features that are generic to\nwhole class of the percolating systems. In particular, we demonstrate existence\nof characteristic aspect ratio for which percolation probability at the\nthreshold is scale invariant and definite parity of the prefactors in\ngeneralized scaling function for the first two percolation probability moments."
    },
    {
        "anchor": "Transformation of dynamical fluctuation into coherent energy: Studies of noise-induced motions are showing that coherent energy can be\nextracted from some kinds of noise in a periodic ratchet.\n  Recently, energetics of Langevin dynamics is formulated by Sekimoto\n[J.Phys.Soc.Jpn, 66 1234 (1997)], which can be applied to ratchet systems\ndescribed by Fokker-Planck equation. In this paper, we derive an energetics of\nratchet systems that can be applied to dynamical-noise-induced motion in a\nstatic potential. Analytical efficiency of the energy transformation is derived\nfor the dynamical noise in an overdumping limit of the system.\n  Comparison between analytical and numerical studies is performed for chaotic\nnoise.",
        "positive": "Magnetic Resonance Imaging of Granular Materials: Magnetic Resonance Imaging (MRI) has become one of the most important tools\nto screen humans in medicine, virtually every modern hospital is equipped with\nan NMR tomograph. The potential of NMR in 3D imaging tasks is by far greater,\nbut there is only 'a handful' of MRI studies of particulate matter. The method\nis expensive, time-consuming, and requires a deep understanding of pulse\nsequences, signal acquisition and processing. We give a short introduction into\nthe physical principles of this imaging technique, describe its advantages and\nlimitations for the screening of granular matter and present a number of\nexamples of different application purposes, from the exploration of granular\npacking, via the detection of flow and particle diffusion, to real dynamic\nmeasurements. Probably, X-ray computed tomography is preferable in most\napplications, but fast imaging of single slices with modern MRI techniques is\nunmatched, and the additional opportunity to retrieve spatially resolved flow\nand diffusion profiles without particle tracking is a unique feature."
    },
    {
        "anchor": "The emergence of cooperativity accompanying vitrification: Insights from\n  density fluctuation dynamics: We discuss the emergence and growth of the cooperativity accompanying\nvitrification based on the density fluctuation dynamics for fragile\nglass-forming liquids. (i) The relaxation of density fluctuations proceeds by\nthe particle (density) exchange process, and is diffusive; that is, the\nallowable kinetic paths are strongly restricted by the local conservation law.\n(ii) In normal liquid states, this exchange process is less cooperative, and\nthe diffusion coefficient of density fluctuations $D_c$ is given as $D_c\\sim\n\\lambda^2/\\tau_\\alpha$, where $\\lambda$ is the particle size and $\\tau_\\alpha$\nis the structural relaxation time. On the other hand, in supercooled states the\nrestriction on the kinetic path is more severe with increasing the degree of\nsupercooling, which makes the exchange process more cooperative, resulting in\n$D_c \\sim \\xi_{\\rm d}^2/\\tau_\\alpha$ with $\\xi_{\\rm d}$ being the cooperative\nlength scale. (iii) The molecular dynamics simulation results show that the\nself-diffusion coefficient of the tagged particle, $D_s$, almost coincides with\n$D_c$, suggesting that the collective density diffusion and the particle\ndiffusion closely share the same mechanism: in normal states $D_s$ determines\n$D_c$, but vice versa in supercooled states. This immediately leads to the idea\nthat the breakdown of the Stokes-Einstein relation is not the anomaly in the\nsingle-particle dynamics but reflects the increase in the cooperativity in the\ndensity diffusion at the length scale of $\\xi_{\\rm d}$.",
        "positive": "Localized orientational order chaperons the nucleation of Rotator phases\n  in hard polyhedral particles: The nucleation kinetics of the rotator phase in hard cuboctahedra, truncated\noctahedra, and rhombic dodecahedra is simulated via a combination of Forward\nFlux Sampling and Umbrella Sampling. For comparable degree of supersaturation,\nthe polyhedra are found to have significantly lower free-energy barriers and\nfaster nucleation rates than hard spheres. This difference primarily stems from\nlocalized orientational ordering, which steers polyhedral particles to pack\nmore efficiently. Orientational order hence fosters here the growth of\norientationally disordered nuclei."
    },
    {
        "anchor": "Motile dissenters disrupt the flocking of active granular matter: We report flocking in the dry active granular matter of millimeter-sized\ntwo-step-tapered rods without an intervening medium. The system undergoes the\nflocking phase transition at a threshold area fraction ~ 0.12 having high\norientational correlations between the particles. However, the one-step-tapered\nrods do not flock and are used as the motile dissenters in the flock-forming\ngranular matter. At the critical fraction of dissenters ~ 0.3, the flocking\norder of the system gets completely destroyed. The variance of the system's\norder parameter shows a maximum near the dissenter fraction f ~ 0.05,\nsuggesting a finite-size crossover between the ordered and disordered phases.",
        "positive": "Auxetic behavior on demand: a three steps recipe for new designs: Despite their outstanding mechanical properties, with many industrial\napplications, a rational and systematic design of new and controlled auxetic\nmaterials remains poorly developed. Here a unified framework is established to\ndescribe bidimensional perfect auxetics with potential use in the design of new\nmaterials. Perfect auxetics are characterized by a Poisson's ratio $\\nu=-1$\nover a finite strain range and can be modeled as materials composed of rotating\nrigid units. Inspired by a natural connection between these rotating rigid\nunits with an antiferromagnetic spin system, here are unveiled the conditions\nfor the emergence of a non-trivial floppy mode responsible for the auxetic\nbehavior. Furthermore, this model paves a simple pathway for the design of new\nauxetic materials, based on three simple steps, which set the sufficient\nconnectivity and geometrical constraints for perfect auxetics. In particular, a\nnew exotic crystal, a Penrose quasi-crystal and the long desired isotropic\nauxetic material are designed and constructed for the first time. Using 3D\nprinted materials, finite element methods and this rigid unit model, the\nauxetic behavior of these designs is shown to be robust under small\ndisturbances in the structure, though the Poisson's ratio value relies on\nsystem's details, approaching $-1$ close to the ideal case."
    },
    {
        "anchor": "Numerical modeling of static equilibria and bifurcations in bigons and\n  bigon rings: In this study, we explore the mechanics of a bigon and a bigon ring from a\ncombination of experiments and numerical simulations. A bigon is a simple\nelastic network consisting of two initially straight strips that are deformed\nto intersect with each other through a fixed intersection angle at each end. A\nbigon ring is a novel multistable structure composed of a series of bigons\narranged to form a loop. We find that a bigon ring usually contains several\nfamilies of stable states and one of them is a multiply-covered loop, which is\nsimilar to the folding behavior of a bandsaw blade. To model bigons and bigon\nrings, we propose a numerical framework combining several existing techniques\nto study mechanics of elastic networks consisting of thin strips. Each strip is\nmodeled as a Kirchhoff rod, and the entire strip network is formulated as a\ntwo-point boundary value problem (BVP) that can be solved by a general-purpose\nBVP solver. Together with numerical continuation, we apply the numerical\nframework to study static equilibria and bifurcations of the bigons and bigon\nrings. Both numerical and experimental results show that the intersection angle\nand the aspect ratio of the strip's cross section contribute to the bistability\nof a bigon and the multistability of a bigon ring; the latter also depends on\nthe number of bigon cells in the ring. The numerical results further reveal\ninteresting connections among various stable states in a bigon ring. Our\nnumerical framework can be applied to general elastic rod networks that may\ncontain flexible joints, naturally curved strips of different lengths, etc. The\nfolding and multistable behaviors of a bigon ring may inspire the design of\nnovel deployable and morphable structures",
        "positive": "Dynamics of a deformable active particle under shear flow: The motion of a deformable active particle in linear shear flow is explored\ntheoretically. Based on symmetry considerations, in two spatial dimensions, we\npropose coupled nonlinear dynamical equations for the particle position,\nvelocity, deformation, and rotation. In our model, both, passive rotations\ninduced by the shear flow as well as active spinning motions, are taken into\naccount. Our equations reduce to known models in the two limits of vanishing\nshear flow and vanishing particle deformability. For varied shear rate and\nparticle propulsion speed, we solve the equations numerically and obtain a\nmanifold of different dynamical modes including active straight motion,\nperiodic motions, motions on undulated cycloids, winding motions, as well as\nquasi-periodic and chaotic motions induced at high shear rates. The types of\nmotion are distinguished by different characteristics in the real-space\ntrajectories and in the dynamical behavior of the particle orientation and its\ndeformation. Our predictions can be verified in experiments on self-propelled\ndroplets exposed to a linear shear flow."
    },
    {
        "anchor": "Structure Function of Polymer Nematic Liquid Crystals: A Monte Carlo\n  Simulation: We present a Monte Carlo simulation of a polymer nematic for varying volume\nfractions, concentrating on the structure function of the sample. We achieve\nnematic ordering with stiff polymers made of spherical monomers that would\notherwise not form a nematic state. Our results are in good qualitative\nagreement with theoretical and experimental predictions, most notably the\nbowtie pattern in the static structure function.",
        "positive": "Stability of Bose-Einstein Condensates Confined in Traps: Bose-Einstein condensation has been realized in dilute atomic vapors. This\nachievement has generated immerse interest in this field. Presented is a review\nof recent theoretical research into the properties of trapped dilute-gas\nBose-Einstein condensates. Among them, stability of Bose-Einstein condensates\nconfined in traps is mainly discussed. Static properties of the ground state\nare investigated by use of the variational method. The anlysis is extended to\nthe stability of two-component condensates. Time-development of the condensate\nis well-described by the Gross-Pitaevskii equation which is known in nonlinear\nphysics as the nonlinear Schr\\\"odinger equation. For the case that the\ninter-atomic potential is effectively attractive, a singularity of the solution\nemerges in a finite time. This phenomenon which we call collapse explains the\nupper bound for the number of atoms in such condensates under traps."
    },
    {
        "anchor": "Radius of Gyration of Randomly Branched Molecules: The mathematical derivation of the mean square radius of gyration, <s2x>, of\nbranched polymers is reinvestigated from a kinetic-equation-point of view. In\nparticular we derive the corresponding quantity of the A-R-Bf-1 model; the\nresult showing that the mean square radius of gyration is precisely identical\nwith that of the R-Af model.",
        "positive": "Order of wetting transitions in electrolyte solutions: For wetting films in dilute electrolyte solutions close to charged walls we\npresent analytic expressions for their effective interface potentials. The\nanalysis of these expressions renders the conditions under which corresponding\nwetting transitions can be first- or second-order. Within mean field theory we\nconsider two models, one with short- and one with long-ranged solvent-solvent\nand solvent-wall interactions. The analytic results reveal in a transparent way\nthat wetting transitions in electrolyte solutions, which occur far away from\ntheir critical point (i.e., the bulk correlation length is less than half of\nthe Debye length) are always first-order if the solvent-solvent and\nsolvent-wall interactions are short-ranged. In contrast, wetting transitions\nclose to the bulk critical point of the solvent (i.e., the bulk correlation\nlength is larger than the Debye length) exhibit the same wetting behavior as\nthe pure, i.e., salt-free, solvent. If the salt-free solvent is governed by\nlong-ranged solvent-solvent as well as long-ranged solvent-wall interactions\nand exhibits critical wetting, adding salt can cause the occurrence of an\nion-induced first-order thin-thick transition which precedes the subsequent\ncontinuous wetting as for the salt-free solvent."
    },
    {
        "anchor": "Glassy dynamics of landscape evolution: Soil creeps imperceptibly downhill, but also fails catastrophically to create\nlandslides. Despite the importance of these processes as hazards and in\nsculpting landscapes, there is no agreed upon model that captures the full\nrange of behavior. Here we examine the granular origins of hillslope soil\ntransport by Discrete Element Method simulations, and re-analysis of\nmeasurements in natural landscapes. We find creep for slopes below a critical\ngradient, where average particle velocity (sediment flux) increases\nexponentially with friction coefficient (gradient). At critical there is a\ncontinuous transition to a dense-granular flow rheology. Slow earthflows and\nlandslides thus exhibit glassy dynamics characteristic of a wide range of\ndisordered materials; they are described by a two-phase flux equation that\nemerges from grain-scale friction alone. This glassy model reproduces\ntopographic profiles of natural hillslopes, showing its promise for predicting\nhillslope evolution over geologic timescales.",
        "positive": "Non-Amontons-Coulomb local friction law of randomly rough contact\n  interfaces with rubber: We report on measurements of the local friction law at a multi-contact\ninterface formed between a smooth rubber and statistically rough glass lenses,\nunder steady state friction. Using contact imaging, surface displacements are\nmeasured, and inverted to extract both distributions of frictional shear stress\nand contact pressure with a spatial resolution of about 10~$\\mu$m. For a glass\nsurface whose topography is self-affine with a Gaussian height asperity\ndistribution, the local frictional shear stress is found to vary strongly\nsub-linearly with the local contact pressure over the whole investigated\npressure range. Such sub-linear behavior is also evidenced for a surface with a\nnon Gaussian height asperity distribution, demonstrating that, for such\nmulti-contact interfaces, Amontons-Coulomb's friction law does not prevail at\nthe local scale."
    },
    {
        "anchor": "Self-assembly of \"Mickey Mouse\" shaped colloids into tube-like\n  structures: experiments and simulations: The self-assembly of anisotropic patchy particles with triangular shape was\nstudied by experiments and computer simulations. The colloidal particles were\nsynthesized in a two-step seeded emulsion polymerization process, and consist\nof a central smooth lobe connected to two rough lobes at an angle of\n$\\sim$90$^{\\circ}$, resembling the shape of a \"Mickey Mouse\" head. Due to the\ndifference in overlap volume, adding an appropriate depletant induces an\nattractive interaction between the smooth lobes of the colloids only, while the\ntwo rough lobes act as steric constraints. The essentially planar geometry of\nthe \"Mickey Mouse\" particles is a first geometric deviation of dumbbell shaped\npatchy particles. This new geometry is expected to form one-dimensional\ntube-like structures rather than spherical, essentially zero-dimensional\nmicelles. At sufficiently strong attractions, we indeed find tube-like\nstructures with the sticky lobes at the core and the non-sticky lobes pointing\nout as steric constraints that limit the growth to one direction, providing the\ntubes with a well-defined diameter but variable length both in experiments and\nsimulations. In the simulations, we found that the internal structure of the\ntubular fragments could either be straight or twisted into so-called Bernal\nspirals.",
        "positive": "Flow and structure in nonequilibrium Brownian many-body systems: We present a fundamental classification of forces relevant in nonequilibrium\nstructure formation under collective flow in Brownian many-body systems. The\ninternal one-body force field is systematically split into contributions\nrelevant for the spatial structure and for the coupled motion. We demonstrate\nthat both contributions can be obtained straightforwardly in computer\nsimulations, and present a power functional theory that describes all types of\nforces quantitatively. Our conclusions and methods are relevant for flow in\ninertial systems, such as molecular liquids and granular media."
    },
    {
        "anchor": "First order phase transitions and the thermodynamic limit: We consider simple mean field continuum models for first order liquid-liquid\ndemixing and solid-liquid phase transitions and show how the Maxwell\nconstruction at phase coexistence emerges on going from finite-size closed\nsystems to the thermodynamic limit. The theories considered are the\nCahn-Hilliard model of phase separation, which is also a model for the\nliquid-gas transition, and the phase field crystal model of the solid-liquid\ntransition. Our results show that states comprising the Maxwell line depend\nstrongly on the mean density with spatially localized structures playing a key\nrole in the approach to the thermodynamic limit.",
        "positive": "Viscous-Viscoelastic Correspondence Principle for Brownian Motion: Motivated from the classical expressions of the mean squared displacement and\nthe velocity autocorrelation function of Brownian particles suspended either in\na Newtonian viscous fluid or trapped in a harmonic potential, we show that for\nall time-scales the mean squared displacement of Brownian microspheres with\nmass $m$ and radius $R$ suspended in any linear, isotropic viscoelastic\nmaterial is identical to the creep compliance of a linear mechanical network\nthat is a parallel connection of the linear viscoelastic material with an\ninerter with distributed inertance, $m_R=\\frac{m}{\\text{6}\\pi R}$. The\nsynthesis of this mechanical network leads to the statement of a\nviscous-viscoelastic correspondence principle for Brownian motion which\nsimplifies appreciably the calculations of the mean squared displacement and\nthe velocity autocorrelation function of Brownian particles suspended in\nviscoelastic materials where inertia effects are non-negligible at longer\ntime-scales. The viscous-viscoelastic correspondence principle established in\nthis paper by introducing the concept of the inerter is equivalent to the\nviscous-viscoelastic analogy adopted by Mason and Weitz (1995)."
    },
    {
        "anchor": "Frank Elastic Constants of Semiflexible Polymer Solutions: We derive the Frank elastic constants for nematic solutions of semiflexible\npolymers. We plot these results as a function of the coarse-grained Maier-Saupe\nquadrupole aligning strength and polymer stiffness ranging from rigid to highly\nflexible. The derivation uses the random phase approximation and combines the\nexact results for the statistics of a worm-like-chain with polymer field theory\nusing a spherical harmonic basis. The results are evaluated using a numerical\ninverse Laplace transform. We present the results in terms of microscopic\nfeatures such as hairpins and polymer ends so the trends can be understood\nindependently from the derivation. Key findings are that for rigid polymers\n$K_{bend}>K_{splay}>K_{twist}$ while for flexible polymers\n$K_{splay}>K_{bend}>K_{twist}$. For rigid polymers, the Frank elastic constants\ngrow with the polymer length. For flexible polymers the elastic constants grow\nwith the persistence length, which becomes the characteristic length scale,\nwith the exception of $K_{splay}$ at high alignment strengths which grows with\npolymer lengths due to the elimination of hairpins.",
        "positive": "Percolation of functionalized colloids on patterned substrates: We study the percolation properties for a system of functionalized colloids\non patterned substrates via Monte Carlo simulations. The colloidal particles\nare modeled as hard disks with three equally-distributed attractive patches on\ntheir perimeter. We describe the patterns on the substrate as circular\npotential wells of radius $R_p$ arranged in a regular square or hexagonal\nlattice. We find a nonmonotonic behavior of the percolation threshold (packing\nfraction) as a function of $R_p$. For attractive wells, the percolation\nthreshold is higher than the one for clean (non-patterned) substrates if the\ncircular wells are non-overlapping and can only be lower if the wells overlap.\nFor repulsive wells we find the opposite behavior. In addition, at high packing\nfractions the formation of both structural and bond defects suppress\npercolation. As a result, the percolation diagram is reentrant with the\nnon-percolated state occurring at very low and intermediate densities."
    },
    {
        "anchor": "Unifying model of driven polymer translocation: We present a Brownian dynamics model of driven polymer translocation, in\nwhich non-equilibrium memory effects arising from tension propagation (TP)\nalong the cis side subchain are incorporated as a time-dependent friction. To\nsolve the effective friction, we develop a finite chain length TP formalism,\nexpanding on the work of Sakaue [Sakaue, PRE 76, 021803 (2007)]. The model,\nsolved numerically, yields results in excellent agreement with molecular\ndynamics simulations in a wide range of parameters. Our results show that\nnon-equilibrium TP along the cis side subchain dominates the dynamics of driven\ntranslocation. In addition, the model explains the different scaling of\ntranslocation time w.r.t chain length observed both in experiments and\nsimulations as a combined effect of finite chain length and pore-polymer\ninteractions.",
        "positive": "Wave polarisation and dynamic degeneracy in a chiral elastic lattice: This paper addresses fundamental questions arising in the theory of\nBloch-Floquet waves in chiral elastic lattice systems. This area has received a\nsignificant attention in the context of \"topologically protected\" waveforms.\nAlthough practical applications of chiral elastic lattices are widely\nappreciated, especially in problems of controlling low-frequency vibrations,\nwave polarisation and filtering, the fundamental questions of the relationship\nof these lattices to classical waveforms associated with longitudinal and shear\nwaves retain a substantial scope for further development. The notion of\nchirality is introduced into the systematic analysis of dispersive elastic\nwaves in a doubly-periodic lattice. Important quantitative characteristics of\nthe dynamic response of the lattice, such as lattice flux and lattice\ncirculation, are used in the analysis along with the novel concept of \"vortex\nwaveforms\" that characterise the dynamic response of the chiral system. We note\nthat the continuum concepts of pressure and shear waves do not apply for waves\nin a lattice, especially in the case when the wavelength is comparable with the\nsize of the elementary cell of the periodic structure. Special critical regimes\nare highlighted when vortex waveforms become dominant. Analytical findings are\naccompanied by illustrative numerical simulations."
    },
    {
        "anchor": "Statistical distributions in the folding of elastic structures: The behaviour of elastic structures undergoing large deformations is the\nresult of the competition between confining conditions, self-avoidance and\nelasticity. This combination of multiple phenomena creates a geometrical\nfrustration that leads to complex fold patterns. By studying the case of a rod\nconfined isotropically into a disk, we show that the emergence of the\ncomplexity is associated with a well defined underlying statistical measure\nthat determines the energy distribution of sub-elements,``branches'', of the\nrod. This result suggests that branches act as the ``microscopic'' degrees of\nfreedom laying the foundations for a statistical mechanical theory of this\nathermal and amorphous system.",
        "positive": "Demixing and tetratic ordering in some binary mixtures of hard\n  superellipses: We examine the fluid phase behaviour of the binary mixture of hard\nsuperellipses using the scaled particle theory The superellipse is a general\ntwo dimensional convex object which can be tuned between circular and\nrectangular shapes continuously at a given aspect ratio. We find that the shape\nof the particle affects strongly the stability of isotropic nematic and\ntetratic phases even if the aspect ratios of both species are fixed. While the\nisotropic isotropic demixing transition can be ruled out using the scaled\nparticle theory the first order isotropic nematic and the nematic nematic\ndemixing transition can be stabilized with strong fractionation between the\ncomponents. It is observed that the demixing tendency is strongest in small\nrectangle large ellipse mixtures. Interestingly, it is possible to stabilize\nthe tetratic order at lower densities in the mixture of hard squares and\nrectangles where the long rectangles form nematic phase, while the squares stay\nin tetratic order."
    },
    {
        "anchor": "Encasement as a morphogenetic mechanism: The case of bending: We study how the encasement of a growing elastic bulk within a possibly\ndifferently growing elastic coat may induce mechanical instabilities in the\nequilibrium shape of the combined body. The inhomogeneities induced in an\nincompressible bulk during growth are also discussed. These effects are\nillustrated through a simple example in which a growing elastic cylinder may\nundergo a shape transition towards a bent configuration.",
        "positive": "Low-Frequency Vibrational States in Ideal Glasses with Random Pinning: Glasses exhibit spatially localized vibrations in the low-frequency regime.\nThese localized modes emerge below the boson peak frequency $\\omega_\\text{BP}$,\nand their vibrational densities of state follow $g(\\omega) \\propto \\omega^4$\n($\\omega$ is frequency). Here, we attempt to address how the localized\nvibrations behave through the ideal glass transition. To do this, we employ a\nrandom pinning method, which enables us to study the thermodynamic glass\ntransition. We find that the localized vibrations survive even in equilibrium\nglass states. Remarkably, the localized vibrations still maintain the\nproperties of appearance below $\\omega_\\text{BP}$ and $g(\\omega) \\propto\n\\omega^4$. Our results provide important insight into the material properties\nof ideal glasses."
    },
    {
        "anchor": "Reciprocal microswimming in fluctuating and confined environments: From bacteria and sperm cells to artificial microrobots, self-propelled\nmicroscopic objects at low Reynolds numbers often perceive fluctuating\nmechanical and chemical stimuli and contact exterior wall boundaries both in\nnature and the laboratory. In this study, we theoretically investigate the\nfundamental features of microswimmers by focusing on their reciprocal\ndeformation. Although the scallop theorem prohibits the net locomotion of\nreciprocal microswimmers, by analyzing a two-sphere swimmer model, we show that\nin a fluctuating and geometrically confined environment, reciprocal\ndeformations can afford a statistically average displacement. After designing\nthe shape gait, a reciprocal swimmer can migrate in any direction, even in the\nstatistical sense, while the statistical average of passive rigid particles\nstatistically diffuses in a particular direction in the presence of external\nboundaries. To elucidate this symmetry breakdown, by introducing an impulse\nresponse function, we derive a general formula for predicting the nonzero net\ndisplacement of a reciprocal swimmer. Using this theory, we determine the\nrelation between the shape gait and net locomotion as well as the net diffusion\nconstant increase and decrease owing to a reciprocal deformation. Based on\nthese findings and a theoretical formulation, we provide a fundamental basis\nfor environment-coupled statistical locomotion. Thus, this study is valuable\nfor understanding biophysical phenomena in fluctuating environments, designing\nartificial microrobots, and conducting laboratory experiments.",
        "positive": "Studying synthesis confinement effects on the internal structure of\n  nanogels in computer simulations: We study the effects of droplet finite size on the structure of nanogel\nparticles synthesized by random crosslinking of molecular polymers diluted in\nnanoemulsions. For this, we use a bead-spring computer model of polymer-like\nstructures that mimics the confined random crosslinking process corresponding\nto irradiation- or electrochemically-induced crosslinking methods. Our results\nindicate that random crosslinking under strong confinement can lead to unusual\nnanogel internal structures, with a central region less dense than the external\none, whereas under moderate confinement the resulting structure has a denser\ncentral region. We analyze the topology of the polymer networks forming nanogel\nparticles with both types of architectures, their overall structural\nparameters, their response to the quality of the solvent and compare the cases\nof non-ionic and ionic systems."
    },
    {
        "anchor": "Shape minimization problems in liquid crystals: We consider a class of liquid crystal free-boundary problems for which both\nthe equilibrium shape and internal configuration of a system must\nsimultaneously be determined, for example in films with air- or fluid-liquid\ncrystal interfaces and elastomers. We develop a finite element algorithm to\nsolve such problems with dynamic mesh control, achieved by supplementing the\nfree energy with an auxiliary functional that promotes mesh quality and is\nminimized in the null space of the energy. We apply this algorithm to a\nflexible capacitor, as well as to determine the shape of liquid crystal\ntactoids as a function of the surface tension and elastic constants. These are\ncompared with theoretical predictions and experimental observations of tactoids\nfrom the literature.",
        "positive": "A Model Ground State of Polyampholytes: The ground state of randomly charged polyampholytes is conjectured to have a\nstructure similar to a necklace, made of weakly charged parts of the chain,\ncompacting into globules, connected by highly charged stretched `strings'. We\nsuggest a specific structure, within the necklace model, where all the neutral\nparts of the chain compact into globules: The longest neutral segment compacts\ninto a globule; in the remaining part of the chain, the longest neutral segment\n(the 2nd longest neutral segment) compacts into a globule, then the 3rd, and so\non. We investigate the size distributions of the longest neutral segments in\nrandom charge sequences, using analytical and Monte Carlo methods. We show that\nthe length of the n-th longest neutral segment in a sequence of N monomers is\nproportional to N/(n^2), while the mean number of neutral segments increases as\nsqrt(N). The polyampholyte in the ground state within our model is found to\nhave an average linear size proportional to sqrt(N), and an average surface\narea proportional to N^(2/3)."
    },
    {
        "anchor": "Phase diagram of a solution undergoing inverse melting: The phase diagram of $\\alpha$-cyclodextrin/water/4-methylpyridine solutions,\na system undergoing inverse melting, has been studied by differential scanning\ncalorimetry, rheological methods, and X-rays diffraction. Two different fluid\nphases separated by a solid region have been observed in the high\n$\\alpha$-cyclodextrin concentration range ($c$$\\geq$150 mg/ml). Decreasing $c$,\nthe temperature interval where the solid phase exists decreases and eventually\ndisappears, and a first order phase transition is observed between the two\ndifferent fluid phases.",
        "positive": "Performance of soft dielectric laminated composites: This paper contains a thorough investigation of the performance of\nelectrically activated layered soft dielectric composite actuators under plane\ndeformation. Noting that the activation can be induced controlling either the\nvoltage or the surface charge, the overall behaviour of the system is obtained\nvia homogenization at large strains taking either the macroscopic electric\nfield or the macroscopic electric displacement field as independent electrical\nvariable. The performance of a two-phase composite actuator compared to that of\nthe homogeneous case is highlighted for few boundary-value problems and for\ndifferent values of stiffness and permittivity ratios between constituents\nbeing significant for applications, where the soft matrix is reinforced by a\nrelatively small volume fraction of a stiff and high-permittivity phase. For\ncharge-controlled devices, it is shown that some composite layouts admit, on\none hand, the occurrence of pull-in/snap-through instabilities that can be\nexploited to design release-actuated systems, on the other, the possibility of\nthickening at increasing surface charge density."
    },
    {
        "anchor": "Liquid crystals in random porous media: Disorder is stronger in\n  low--density aerosils: The nature of glass phases of liquid crystals in random porous media depends\non the effective disorder strength. We study how the disorder strength depends\non the density of the porous media and demonstrate that it can increase as the\ndensity decreases. We also show that the interaction of the liquid crystal with\nrandom porous media can destroy long--range order inside the pores.",
        "positive": "Simulation of Electric Double Layers around Charged Colloids in Aqueous\n  Solution of Variable Permittivity: The ion distribution around charged colloids in solution has been\ninvestigated intensely during the last decade. However, few theoretical\napproaches have included the influence of variation in the dielectric\npermittivity within the system, let alone in the surrounding solvent. In this\narticle, we introduce two relatively new methods that can solve the Poisson\nequation for systems with varying permittivity. The harmonic interpolation\nmethod (HIM) approximately solves the Green's function in terms of a spherical\nharmonics series, and thus provides analytical ion-ion potentials for the\nHamiltonian of charged systems. The Maxwell Equations Molecular Dynamics (MEMD)\nalgorithm features a local approach to electrostatics, allowing for arbitrary\nlocal changes of the dielectric constant. We show that the results of both\nmethods are in very good agreement. We also found that the renormalized charge\nof the colloid, and with it the effective far field interaction, significantly\nchanges if the dielectric properties within the vicinity of the colloid are\nchanged."
    },
    {
        "anchor": "Diffusion and Chemical Potential in Polymer Solutions: We give a mathematical proof for the preceding derivation of the excluded\nvolume theory on the basis of the thermodynamic theory, the concept of\ndiffusion, and the theory of total differential.",
        "positive": "Charge inversion of colloids in an exactly solvable model: We study a two-dimensional model for a long cylindrical stiff charged\nmacroion immersed in a charge-asymmetric electrolyte with charge ratio +2/-1.\nThe model is integrable and it allows an exact analytical determination of the\neffective charge of the macroion, which characterizes the electrostatic\npotential at large distances (compared to the screening length) from the\nmacroion. At at high coulombic coupling, this model predicts charge inversion:\nfor a highly negatively charged macroion, the effective charge could become\npositive, indicating an overscreening of the macroion by the divalent\ncounterions. By studying the behavior of the coions and counterions density\nprofiles close to the macroion, we show that the counterion condensation\nthreshold is shifted to a lower value in absolute value. This plays an\nimportant role in the charge inversion phenomenon."
    },
    {
        "anchor": "Particle dynamics in colloidal suspensions above and below the\n  glass-liquid re-entrance transition: We study colloidal particle dynamics of a model glass system using confocal\nand fluorescence microscopy as the sample evolves from a hard-sphere glass to a\nliquid with attractive interparticle interactions. The transition from\nhard-sphere glass to attractive liquid is induced by short-range depletion\nforces. The development of liquid-like structure is indicated by particle\ndynamics. We identify particles which exhibit substantial motional events and\ncharacterize the transition using the properties of these motional events. As\nsamples enter the attractive liquid region, particle speed during these\nmotional events increases by about one order of magnitude, and the particles\nmove more cooperatively. Interestingly, colloidal particles in the attractive\nliquid phase do not exhibit significantly larger displacements than particles\nin the hard-sphere glass.",
        "positive": "Nonlinear, electrocatalytic swimming in the presence of salt: A small, bimetallic particle in a hydrogen peroxide solution can propel\nitself by means of an electrocatalytic reaction. The swimming is driven by a\nflux of ions around the particle. We model this process for the presence of a\nmonovalent salt, where reaction-driven proton currents induce salt ion\ncurrents. A theory for thin diffuse layers is employed, which yields nonlinear,\ncoupled transport equations. The boundary conditions include a compact Stern\nlayer of adsorbed ions. Electrochemical processes on the particle surface are\nmodeled with a first order reaction of the Butler-Volmer type. The equations\nare solved numerically for the swimming speed. An analytical approximation is\nderived under the assumption that the decomposition of hydrogen peroxide occurs\nmainly without inducing an electric current. We find that the swimming speed\nincreases linearly with hydrogen peroxide concentration for small\nconcentrations. The influence of ion diffusion on the reaction rate can lead to\na concave shape of the function of speed vs. hydrogen peroxide concentration.\nThe compact layer of ions on the particle diminishes the reaction rate and\nconsequently reduces the speed. Our results are consistent with published\nexperimental data."
    },
    {
        "anchor": "Self-Propulsion of Droplets by Spatially-Varying Roughness: Under partial wetting conditions, making a substrate uniformly rougher\nenhances the wetting characteristics of the corresponding smooth substrate {--}\nhydrophilic systems become even more hydrophilic and hydrophobic systems even\nmore hydrophobic. Here we show that spatial texturing of the roughness may lead\nto spontaneous propulsion of droplets. Individual droplets are driven toward\nregions of maximal roughness for intrinsically hydrophilic systems and toward\nregions of minimal roughness for intrinsically hydrophobic systems. Spatial\ntexturing can be achieved by wrinkling the substrate with sinusoidal grooves\nwhose wavelength varies in one direction (inhomogeneous wrinkling) or\nlithographically etching a radial pattern of fractal (Koch curve) grooves on\nthe substrate. Richer energy landscapes for droplet trajectories can be\ndesigned by combining roughness texturing with chemical or material patterning\nof the substrate.",
        "positive": "Comment on \"The effect of the charge density of microemulsion droplets\n  on the bending elasticity of their amphiphilic film\", J. Chem. Phys. 114,\n  10105 (2001): It is shown that the work by Farago and Gradzielski [J. Chem. Phys. 114,\n10105 (2001)] is based on incorrect expressions for the scattering functions,\ncontains a number of other serious defects, and should be revised."
    },
    {
        "anchor": "Normal stresses, contraction, and stiffening in sheared elastic networks: When elastic solids are sheared, a nonlinear effect named after Poynting\ngives rise to normal stresses or changes in volume. We provide a novel relation\nbetween the Poynting effect and the microscopic Gr\\\"uneisen parameter, which\nquantifies how stretching shifts vibrational modes. By applying this relation\nto random spring networks, a minimal model for, e.g., biopolymer gels and solid\nfoams, we find that networks contract or develop tension because they vibrate\nfaster when stretched. The amplitude of the Poynting effect is sensitive to the\nnetwork's linear elastic moduli, which can be tuned via its preparation\nprotocol and connectivity. Finally, we show that the Poynting effect can be\nused to predict the finite strain scale where the material stiffens under\nshear.",
        "positive": "Cluster glasses of ultrasoft particles: We present molecular dynamics (MD) simulations results for dense fluids of\nultrasoft, fully-penetrable particles. These are a binary mixture and a\npolydisperse system of particles interacting via the generalized exponential\nmodel, which is known to yield cluster crystal phases for the corresponding\nmonodisperse systems. Because of the dispersity in the particle size, the\nsystems investigated in this work do not crystallize and form disordered\ncluster phases. The clustering transition appears as a smooth crossover to a\nregime in which particles are mostly located in clusters, isolated particles\nbeing infrequent. The analysis of the internal cluster structure reveals\nmicrosegregation of the big and small particles, with a strong\nhomo-coordination in the binary mixture. Upon further lowering the temperature\nbelow the clustering transition, the motion of the clusters' centers-of-mass\nslows down dramatically, giving way to a cluster glass transition. In the\ncluster glass, the diffusivities remain finite and display an activated\ntemperature dependence, indicating that relaxation in the cluster glass occurs\nvia particle hopping in a nearly arrested matrix of clusters. Finally we\ndiscuss the influence of the microscopic dynamics on the transport properties\nby comparing the MD results with Monte Carlo simulations."
    },
    {
        "anchor": "Multiscale Simulations for Polymeric Flow: Multiscale simulation methods have been developed based on the local stress\nsampling strategy and applied to three flow problems with different difficulty\nlevels: (a) general flow problems of simple fluids, (b) parallel\n(one-dimensional) flow problems of polymeric liquids, and (c) general (two- or\nthree-dimensional) flow problems of polymeric liquids. In our multiscale\nmethods, the local stress of each fluid element is calculated directly by\nperforming microscopic or mesoscopic simulations according to the local flow\nquantities instead of using any constitutive relations. For simple fluids (a),\nsuch as the Lenard-Jones liquid, a multiscale method combining MD and CFD\nsimulations is developed based on the local equilibrium assumption without\nmemories of the flow history. (b), the multiscale method is extended to take\ninto account the memory effects that arise in hydrodynamic stress due to the\nslow relaxation of polymer-chain conformations. The memory of polymer dynamics\non each fluid element is thus resolved by performing MD simulations in which\ncells are fixed at the mesh nodes of the CFD simulations.For general (two- or\nthree-dimensional) flow problems of polymeric liquids (c), it is necessary to\ntrace the history of microscopic information such as polymer-chain\nconformation, which carries the memories of past flow history, along the\nstreamline of each fluid element. A Lagrangian-based CFD is thus implemented to\ncorrectly advect the polymer-chain conformation consistently with the flow. On\neach fluid element, coarse-grained polymer simulations are carried out to\nconsider the dynamics of entangled polymer chains that show extremely slow\nrelaxation compared to microscopic time scales.",
        "positive": "The actin cortex as an active wetting layer: Using active gel theory we study theoretically the properties of the cortical\nactin layer of animal cells. The cortical layer is described as a\nnon-equilibrium wetting film on the cell membrane. The actin density is\napproximately constant in the layer and jumps to zero at its edge. The layer\nthickness is determined by the ratio of the polymerization velocity and the\ndepolymerization rate of actin."
    },
    {
        "anchor": "Active Brownian Particles in Random and Porous Environments: The transport of active particles may occur in complex environments, in which\nit emerges from the interplay between the mobility of the active components and\nthe quenched disorder of the environment. Here we explore structural and\ndynamical properties of Active Brownian Particles (ABPs) in random environments\ncomposed of fixed obstacles in three dimensions. We consider different\narrangements of the obstacles. In particular, we consider two particular\nsituations corresponding to experimentally realizable settings. Firstly, we\nmodel pinning particles in (non--overlapping) random positions and secondly in\na percolating gel structure, and provide an extensive characterization of the\nstructure and dynamics of ABPs in these complex environments. We find that the\nconfinement increases the heterogeneity of the dynamics, with new populations\nof absorbed and localized particles appearing close to the obstacles. This\nheterogeneity has a profound impact on the motility induced phase separation\n(MIPS) exhibited by the particles at high activity, ranging from nucleation and\ngrowth in random disorder to a complex phase separation in porous environments.",
        "positive": "Current reversal in polar flock at order-disorder interface: We studied a system of polar self-propelled particles (SPPs) on a thin\nrectangular channel designed into three regions of order-disorder-order. The\ndivision of the three regions is made on the basis of the noise SPPs experience\nin the respective regions. The noise in the two wide region is chosen lower\nthan the critical noise of order-disorder transition and noise in the middle\nregion or interface is higher than the critical noise. This make the geometry\nof the system analogous to the Josephson Junction (JJ) in solid state physics.\nKeeping all other parameters fixed, we study the properties of the moving SPPs\nin the bulk as well as along the interface for different widths of the\njunction. On increasing interface width, system shows a order-to-disorder\ntransition from coherent moving SPPs in the whole system to the interrupted\ncurrent for large interface width. Surprisingly, inside the interface we\nobserved the current reversal for intermediate widths of the interface. Such\ncurrent reversal is due to the strong randomness present inside the interface,\nthat makes the wall of the interface reflecting. Hence Our study give a new\ninteresting collective properties of SPPs at the interface which can be useful\nto design devices like switch using active agents."
    },
    {
        "anchor": "The first passage problem for diffusion through a cylindrical pore with\n  sticky walls: We calculate the first passage time distribution for diffusion through a\ncylindrical pore with sticky walls. A particle diffusively explores the\ninterior of the pore through a series of binding and unbinding events with the\ncylinder wall. Through a diagrammatic expansion we obtain first passage time\nstatistics for the particle's exit from the pore. Connections between the model\nand nucleocytoplasmic transport in cells are discussed.",
        "positive": "Ptychographic X-ray computed tomography of extended colloidal networks\n  in food emulsions: As a main structural level in colloidal food materials, extended colloidal\nnetworks are important for texture and rheology. By obtaining the 3D\nmicrostructure of the network, macroscopic mechanical properties of the\nmaterial can be inferred. However, this approach is hampered by the lack of\nsuitable non-destructive 3D imaging techniques with submicron resolution.\n  We present results of quantitative ptychographic X-ray computed tomography\napplied to a palm kernel oil based oil-in-water emulsion. The measurements were\ncarried out at ambient pressure and temperature. The 3D structure of the\nextended colloidal network of fat globules was obtained with a resolution of\naround 300 nm. Through image analysis of the network structure, the fat globule\nsize distribution was computed and compared to previous findings. In further\nsupport, the reconstructed electron density values were within 4% of reference\nvalues."
    },
    {
        "anchor": "Cellular Automata for One-Lane Traffic Flow Modelling: Safety and\n  Automation: In recent years the modelling of traffic flow using methods from statistical\nphysics, especially cellular automata models have allowed simulations of large\ntraffic networks faster than real time. In this paper, we study a probabilistic\ncellular automaton model for microsimulations of traffic flow of automated\nvehicles in highways. This model describes single-lane traffic flow on a ring.\nWe study the equilibrium properties by including a parameter of safe distance\nin the model and calculate the so-called fundamental diagrams (flow vs. density\ngraph) considering parallel dynamics. This is done numerically by computer\nsimulations of the model and by means of an analysis of speed variance.",
        "positive": "Reentrance effect in the lane formation of driven colloids: Recently it has been shown that a strongly interacting colloidal mixture\nconsisting of oppositely driven particles, undergoes a nonequilibrium\ntransition towards lane formation provided the driving strength exceeds a\nthreshold value. We predict here a reentrance effect in lane formation: for\nfixed high driving force and increasing particle densities, there is first a\ntransition towards lane formation which is followed by another transition back\nto a state with no lanes. Our result is obtained both by Brownian dynamics\ncomputer simulations and by a phenomenological dynamical density functional\ntheory."
    },
    {
        "anchor": "Geometric order parameters derived from the Voronoi tessellation show\n  signatures of the jamming transition: A jammed packing of frictionless spheres at zero temperature is perfectly\nspecified by the network of contact forces from which mechanical properties can\nbe derived. However, we can alternatively consider a packing as a geometric\nstructure, characterized by a Voronoi tessellation which encodes the local\nenvironment around each particle. We find that this local environment\ncharacterizes systems both above and below jamming and changes markedly at the\ntransition. A variety of order parameters derived from this tessellation carry\nsignatures of the jamming transition, complete with scaling exponents.\nFurthermore, we define a real space geometric correlation function which also\ndisplays a signature of jamming. Taken together, these results demonstrate the\nvalidity and usefulness of a purely geometric approach to jamming.",
        "positive": "How Segmental Dynamics and Mesh Confinement Determine the Selective\n  Diffusivity of Molecules in Crosslinked Dense Polymer Networks: The diffusion of molecules (penetrants) of variable size, shape, and\nchemistry through dense crosslinked polymer networks is a fundamental\nscientific problem that is broadly relevant in materials, polymer, physical and\nbiological chemistry. Relevant applications include molecular separations in\nmembranes, barrier materials for coatings, drug delivery, and nanofiltration. A\nmajor open question is the relationship between molecular transport,\nthermodynamic state, and chemical structure of the penetrant and polymeric\nmedia. Here we address this question by combining experiment, simulation, and\ntheory to unravel the competing effects of penetrant chemistry on its transport\nin rubbery and supercooled polymer permanent networks over a wide range of\ncrosslink densities, size ratios, and temperatures. The crucial importance of\nthe coupling of local penetrant hopping to the polymer structural relaxation\nprocess, and the secondary importance of geometric mesh confinement effects,\nare established. Network crosslinks induce a large slowing down of nm-scale\npolymer relaxation which greatly retards the rate of penetrant activated\nrelaxation. The demonstrated good agreement between experiment, simulation, and\ntheory provides strong support for the size ratio variable (effective penetrant\ndiameter to the polymer Kuhn length) as a key variable, and the usefulness of\ncoarse-grained simulation and theoretical models that average over Angstrom\nscale chemical details. The developed microscopic theory provides a fundamental\nunderstanding of the physical processes underlying the behaviors observed in\nexperiment and simulation. Penetrant transport is theoretically predicted to\nbecome even more size sensitive in a more deeply supercooled regime not probed\nin our present experiments or simulations, which suggests new strategies for\nenhancing selective polymer membrane design."
    },
    {
        "anchor": "Protein folding, anisotropic collapse and blue phases: We study a homopolymer model of a protein chain, where each monomer carries a\ndipole moment. To mimic the geometry of the peptidic bond, these dipoles are\nconstrained to be locally perpendicular to the chain. The tensorial character\nof the dipolar interaction leads naturally to a (tensorial) liquid crystal-like\norder parameter. For non chiral chains, a mean field study of this model shows\nthat a classical $\\theta$ collapse transition occurs first; at lower\ntemperature, nematic order sets in. For chiral chains, an anisotropic\n(tensorial) collapse transition may occur before the $\\theta$ temperature is\nreached: the ordered phase can be described as a ``compact phase of secondary\nstructures'', and possesses great similarities with the liquid crystal blue\nphases.",
        "positive": "Multiple liquid-liquid critical points and anomalies in core-softened\n  potentials: The relation between liquid-liquid phase transitions and waterlike density\nanomalies in core-softened potentials of fluids was investigated in an exactly\nsolvable one dimensional lattice model and a in a three dimensional fluid with\nfermi-like potential, the latter by molecular dynamics. Both systems were shown\nto present three liquid phases, two liquid-liquid phase transitions closely\nconnected to two distinct regions of anomalous density increase. We propose\nthat an oscillatory behavior observed on the thermal expansion coefficient as a\nfunction of pressure can be used as a signature of the connection between\nliquid-liquid phase and density."
    },
    {
        "anchor": "Soft topological modes protected by symmetry in rigid mechanical\n  metamaterials: Topological mechanics can realize soft modes in mechanical metamaterials in\nwhich the number of degrees of freedom for particle motion is finely balanced\nby the constraints provided by interparticle interactions. However, solid\nobjects are generally hyperstatic (or overconstrained). Here, we show how\nsymmetries may be applied to generate topological soft modes even in\noverconstrained, rigid systems. To do so, we consider non-Hermitian topology\nbased on non-square matrices, and design a hyperstatic material in which\nlow-energy modes protected by topology and symmetry appear at interfaces. Our\napproach presents a novel way of generating softness in robust scale-free\narchitectures suitable for miniaturization to the nanoscale.",
        "positive": "Composite search of active particles in three-dimensional space based on\n  non-directional cues: We theoretically address minimal search strategies of active, self-propelled\nparticles towards hidden targets in three-dimensional space. The particles can\nsense if a target is close, e.g., by detecting signaling molecules released by\na target, but they cannot deduce any directional cues. We focus on composite\nsearch strategies, where particles switch between extensive outer search and\nintensive inner search; inner search is started when the proximity of a target\nis detected and ends again when a certain inner search time has elapsed. In the\nsimplest strategy, active particles move ballistically during outer search, and\ntransiently reduce their directional persistence during inner search. In a\nsecond, adaptive strategy, particles exploit a dynamic scattering effect by\nreducing directional persistence only outside a well-defined target zone. These\ntwo search strategies require only minimal information processing capabilities\nand a single binary or tertiary internal state, respectively, yet increases the\nrate of target encounter substantially. The optimal inner search time scales as\na power-law with exponent -2/3 with target density, reflecting a trade-off\nbetween exploration and exploitation."
    },
    {
        "anchor": "Molecular dynamics investigation of a model ionic liquid lubricant for\n  automotive applications: In the current work we present a new modelling approach for simulating\nmeso-scopic phenomena related to lubrication of the piston ring-cylinder liner\ncontact. Our geometry allows a variable confinement gap and a varying amount of\nlubricant in the gap, while avoiding the squeeze-out of the lubricant into\nvacuum. We have implemented a coarse grain molecular dynamics description of an\nionic liquid as a lubricant which can expand into lateral reservoirs. The\nresults have revealed two regimes of lubrication, an elasto-hydrodynamic one\nunder low loads and one with low, velocity-independent specific friction, under\nhigh loads. The observed steep rise of normal forces at small plate-to-plate\ndistances is an interesting behaviour that could potentially be exploited for\npreventing solid-solid contact and wear.",
        "positive": "Statistics of Conserved Quantities in Mechanically Stable Packings of\n  Frictionless Disks Above Jamming: We numerically simulate mechanically stable packings of soft-core,\nfrictionless, bidisperse disks in two dimensions, above the jamming packing\nfraction $\\phi_J$. For configurations with a fixed isotropic global stress\ntensor, we compute the averages, variances, and correlations of conserved\nquantities (stress $\\Gamma_{\\cal C}$, force-tile area $A_{\\cal C}$, Voronoi\nvolume $V_{\\cal C}$, number of particles $N_{\\cal C}$, and number of small\nparticles $N_{s{\\cal C}}$) on compact subclusters of particles ${\\cal C}$, as a\nfunction of the cluster size and the global system stress. We find several\nsignificant differences depending on whether the cluster ${\\cal C}$ is defined\nby a fixed radius $R$ or a fixed number of particles $M$. We comment on the\nimplications of our findings for maximum entropy models of jammed packings."
    },
    {
        "anchor": "Mechanical Yield in Amorphous Solids: a First-Order Phase Transition: Amorphous solids yield at a critical value of the strain (in strain\ncontrolled experiments); for larger strains the average stress can no longer\nincrease - the system displays an elasto-plastic steady state. A long standing\nriddle in the materials community is what is the difference between the\nmicroscopic states of the material before and after yield. Explanations in the\nliterature are material specific, but the universality of the phenomenon begs a\nuniversal answer. We argue here that there is no fundamental difference in the\nstates of matter before and after yield, but the yield is a bona-fide first\norder phase transition between a highly restricted set of possible\nconfigurations residing in a small region of phase space to a vastly rich set\nof configurations which include many marginally stable ones. To show this we\nemploy an order parameter of universal applicability, independent of the\nmicroscopic interactions, that is successful in quantifying the transition in\nan unambiguous manner.",
        "positive": "Differences in cell death and division rules can alter tissue rigidity\n  and fluidization: Tissue mechanical properties such as rigidity and fluidity, and changes in\nthese properties driven by jamming-unjamming transitions (UJT), have come under\nrecent highlight as mechanical markers of health and disease in various\nbiological processes including cancer. However, most analysis of these\nmechanical properties and UJT have sidestepped the effect of cellular death and\ndivision in these systems. Cellular apoptosis (programmed cell death) and\nmitosis (cell division) can drive significant changes in tissue properties. The\nbalance between the two is crucial in maintaining tissue function, and an\nimbalance between the two is seen in situations such as cancer progression,\nwound healing and necrosis. In this work we investigate the impact of cell\ndeath and division on tissue mechanical properties, by incorporating specific\nmechanosensitive triggers of cell death and division based on the size and\ngeometry of the cell within in silico models of tissue dynamics. Specifically,\nwe look at cell migration, tissue response to external stress, tissue extrusion\npropensity and self-organization of different cell types within the tissue, as\na function of cell death and division and the rules that trigger these events.\nWe find that not only do cell death and division events significantly alter\ntissue mechanics when compared to systems without these events, but that the\nchoice of triggers driving these cell death and division events also alter the\npredicted tissue mechanics and overall system behavior."
    },
    {
        "anchor": "Asymmetry in cilia configuration induces hydrodynamic phase locking: To gain insight into the nature of biological synchronization at the\nmicroscopic scale, we here investigate the hydrodynamic synchronization between\nconically rotating objects termed nodal cilia. A mechanical model of three\nrotating cilia is proposed with consideration of variation in their shapes and\ngeometrical arrangement. We conduct numerical estimations of both near-field\nand far-field hydrodynamic interactions, and apply a conventional averaging\nmethod for weakly coupled oscillators. In the non-identical case, the three\ncilia showed stable locked-phase differences around $\\pm \\pi/2$. However, such\nphase locking also occurred with three identical cilia when allocated in a\ntriangle except for the equilateral triangle. The effects of inhomogeneity in\ncilia shapes and geometrical arrangement on such asymmetric interaction is\ndiscussed to understand the role of biological variation in synchronization via\nhydrodynamic interactions.",
        "positive": "Packing of softly repulsive particles in a spherical box - a generalised\n  Thomson problem: We study the (near or close to) ground state distribution of N softly\nrepelling particles trapped in the interior of a spherical box. The charges\nmutually interact via an inverse power law potential of the form $1/r^\\gamma$.\nWe study three regimes in which the charges form an single spherical shell at\nthe edge of the box ($\\gamma=1$), a series of concentric shells of increasing\ndensity ($\\gamma=2$) and $\\gamma=12$ for which the charges form shells with a\nmore uniform charge distribution. We conduct numerical simulations for clusters\ncontaining up to 5000 charges and compare charge density across the system with\ncontinuum limit results. The agreement between numerical (discrete) results and\nthe continuum limit is found to improve with increasing N."
    },
    {
        "anchor": "Interfacial solvation explains attraction between like-charged objects\n  in aqueous solution: Over the past few decades the experimental literature has consistently\nreported observations of attraction between like-charged colloidal particles\nand macromolecules in solution. Examples include nucleic acids and colloidal\nparticles in bulk solution and under confinement, and biological liquid-liquid\nphase separation. This observation is at odds with the intuitive expectation of\nan interparticle repulsion that decays monotonically with distance. Although\nattraction between like-charged particles can be theoretically rationalised in\nthe strong-coupling regime, for example, in the presence of multivalent\ncounterions, recurring accounts of long-range attraction in aqueous solution\ncontaining monovalent ions at low ionic strength have posed an open conundrum.\nHere we show that the behaviour of molecular water at an interface -\ntraditionally disregarded in the continuum electrostatics picture, provides a\nmechanism to explain attraction between like-charged objects in a broad\nspectrum of experiments. This basic principle will have important ramifications\nin the ongoing quest to better understand intermolecular interactions in\nsolution.",
        "positive": "Segregation models for density-bidisperse granular flows: Individual constituent balance equations are often used to derive expressions\nfor species-specific segregation velocities in flows of dense granular\nmixtures. We propose a semiempirical expression for the interspecies momentum\nexchange in density-bidisperse granular flows as an extension of ideas from\nkinetic theory and compare it to a previous viscous drag approach that is\nanalogous to particles settling in a fluid. The proposed model expands the\nrange of the granular kinetic theory from short-duration binary collisions to\nthe multiple enduring contacts characteristic of dense shear flows and\nincorporates the effects of particle friction, concentration ratio, and local\nflow conditions. The segregation velocities derived from the momentum balance\nequation using both interspecies drag models match the downward and upward\nsegregation velocities of heavy and light particles obtained from DEM\nsimulations through the flowing layer depth for different density ratios and\nconstituent concentrations in confined shear flows. Predictions of the kinetic\ntheory inspired approach are additionally compared to results from free surface\nheap flow simulations, and, again, a close match is observed."
    },
    {
        "anchor": "Local orientational order in the Stockmayer liquid: Phase behaviour of the Stockmayer fluid is studied with a method similar to\nthe Monte-Carlo annealing scheme. We introduce a novel order parameter which is\nsensitive to the local co-orientation of the dipoles of particles in the fluid.\nWe exhibit a phase diagram based on the behaviour of the order parameter in the\ndensity region 0.1 \\leq {\\rho}\\ast \\leq 0.32. Specifically, we observe and\nanalyse a second order locally disordered fluid \\rightarrow locally oriented\nfluid phase transition.",
        "positive": "New insights into the capillary retention force and the work of adhesion: We calculate the normal capillary retention force that anchors a drop to a\nsolid surface in the direction perpendicular to the surface, and study the\nrelationship between such force and the Young-Dupre work of adhesion. We also\ncalculate the work necessary to create or destroy a patch of solid-liquid\ninterface by moving the triple line on a solid substrate. We argue that when\nthe capillary number is small and a drop is sliding on a surface at constant\nspeed, the lateral retention force is the major source of energy dissipation,\nwhereas viscous dissipation plays a minor role."
    },
    {
        "anchor": "Spontaneous ordering of a bacterial drop into a spiral vortex: In this fluid dynamics video we explore the nature and causes of the\nspontaneous ordering that emerges in a dense bacterial suspension under\nconfinement. Recent experiments with B. Subtilis confined within small\nflattened drops show that the bacteria form a steady single-vortex state with a\ncounterrotating cell boundary layer. Using simulations that capture oriented\ncell-cell and cell-fluid interactions, we show that hydrodynamics is crucial in\nreproducing and explaining the phenomenon. We give new insights into the\nmicroscopic arrangement of the bacteria, which are confirmed by new\nexperiments.",
        "positive": "Molecular Insights into the Electrowetting Behavior of Aqueous Ionic\n  Liquid: Molecular dynamics simulations were employed to study the wetting behavior of\nnanoscale aqueous hydrophilic and hydrophobic Imidazolium based ionic liquid\n(IL) droplets on a solid graphite substrate subjected to the perpendicular\nelectric field. Imminent transformation in the droplet configuration was\nobserved at E = 0.08 V/{\\AA} both for hydrophobic ILs [EMIM][NTF2] and SPC/E\nwater droplets. However, for hydrophilic, [EMIM][BF4], the droplet wets\nasymmetrically within electric field E = 0.09 V/{\\AA} for lower weight\npercentages of ILs and E = 0.1 V/{\\AA} at a higher weight percentage of ILs\n(i.e., 50wt%), because of the strong interaction of ILs with the sheet. We\nexplore the impact of electric-field through various parameters such as mass\ndensity distribution, contact angle, orientation, and hydrogen bonds. Keywords:\nelectro-wetting; contact angle; aqueous hydrophilic and hydrophobic Imidazolium\nILs, molecular dynamic simulation"
    },
    {
        "anchor": "Dirac cones and chiral selection of elastic waves in a soft strip: We study the propagation of in-plane elastic waves in a soft thin strip; a\nspecific geometrical and mechanical hybrid framework which we expect to exhibit\nDirac-like cone. We separate the low frequencies guided modes (typically 100 Hz\nfor a centimetre wide strip) and obtain experimentally the full dispersion\ndiagram. Dirac cones are evidenced together with other remarkable wave\nphenomena such as negative wave velocity or pseudo-zero group velocity (ZGV).\nOur measurements are convincingly supported by a model (and numerical\nsimulation) for both Neumann and Dirichlet boundary conditions. Finally, we\nperform one-way chiral selection by carefully setting the source position and\npolarization. Therefore, we show that soft materials support atypical\nwave-based phenomena, which is all the more interesting as they make most of\nthe biological tissues.",
        "positive": "Phoretic colloids close to and trapped at fluid interfaces: The active motion of phoretic colloids leads them to accumulate at boundaries\nand interfaces. Such an excess accumulation, with respect to their passive\ncounterparts, makes the dynamics of phoretic colloids particularly sensitive to\nthe presence of boundaries and pave new routes to externally control their\nsingle particle as well as collective behavior. Here we review some recent\ntheoretical results about the dynamics of phoretic colloids close to and\nadsorbed at fluid interfaces in particular highlighting similarities and\ndifferences with respect to solid-fluid interfaces."
    },
    {
        "anchor": "Non-monotonic flow curves of shear thickening suspensions: The discontinuous shear thickening (DST) of dense suspensions is a remarkable\nphenomenon in which the viscosity can increase by several orders of magnitude\nat a critical shear rate. It has the appearance of a first order phase\ntransition between two hypothetical \"states\" that we have recently identified\nas Stokes flows with lubricated or frictional contacts, respectively. Here we\nextend the analogy further by means of novel stress-controlled simulations and\nshow the existence of a non-monotonic steady-state flow curve analogous to a\nnon-monotonic equation of state. While we associate DST with an S-shaped flow\ncurve, at volume fractions above the shear jamming transition the frictional\nstate loses flowability and the flow curve reduces to an arch, permitting the\nsystem to flow only at small stresses. Whereas a thermodynamic transition leads\nto phase separation in the coexistence region, we observe a uniform shear flow\nall along the thickening transition. A stability analysis suggests that uniform\nshear may be mechanically stable for the small Reynolds numbers and system\nsizes in a rheometer.",
        "positive": "Geometric frustration and compatibility conditions for two dimensional\n  director fields: The uniform director field obtained for the nematic ground state of the\nhard-rod model of liquid crystals in two dimensions reflects the high symmetry\nof the constituents of the liquid; It is a manifestation of the constituents'\nlocal tendency to avoid splaying and bending with respect to one another. In\ncontrast, bent-core (or banana shaped) liquid-crystal-forming-molecules locally\nfavor a state of zero splay and constant bend. However, such a structure cannot\nbe realized in the plane and the resulting liquid-crystalline phase is\nfrustrated and must exhibit some compromise of these two mutually contradicting\nlocal intrinsic tendencies. The generation of geometric frustration from the\nintrinsic geometry of the constituents of a material is not only natural and\nubiquitous but also leads to a striking variety of morphologies of ground\nstates and exotic response properties.\n  In this work we establish the necessary and sufficient conditions for two\nscalar functions, $s$ and $b$ to describe the splay and bend of a director\nfield in the plane. We generalize these compatibility conditions for geometries\nwith non-vanishing constant Gaussian curvature, and provide a reconstruction\nformula for the director field depending only on the splay and bend fields and\ntheir derivatives. Last, we discuss optimal compromises for simple incompatible\ncases where the locally preferred values of the splay and bend cannot be\nglobally achieved."
    },
    {
        "anchor": "Random copolymer adsorption: Morita approximation compared to exact\n  numerical simulations: We study the adsorption of ideal random lattice copolymers with correlations\nin the sequences on homogeneous substrates with two different methods: An\nanalytical solution of the problem based on the constrained annealed\napproximation introduced by Morita in 1964 and the generating functional (GF)\ntechnique, and direct numerical simulations of lattice chains averaged over\nmany realizations of random sequences. Both methods allow to calculate the free\nenergy and different conformational characteristics of the adsorbed chain. The\ncomparison of the results for random copolymers with different degree of\ncorrelations and different types of nonadsorbing monomers (neutral or repelling\nfrom the surface) shows not only qualitative but a very good quantitative\nagreement, especially in the cases of Bernoullian and quasi-alternating random\nsequences.",
        "positive": "Directional self-locomotion of active droplets enabled by nematic\n  environment: Active matter comprised of self-propelled interacting units holds a major\npromise for extraction of useful work from its seemingly chaotic\nout-of-equilibrium dynamics. Streamlining active matter to produce work is\nespecially important at microscale, where the viscous forces prevail over\ninertia and the useful modes of transport require very specific non-reciprocal\ntype of motion. Here we report that microscopic active droplets representing\naqueous dispersions of swimming bacteria Bacillus subtilis show unidirectional\npropulsion when placed in an inactive nematic medium. Random motion of bacteria\ninside the droplet is rectified into a directional self-locomotion of the\ndroplet by the polar director structure that the droplet itself creates in the\nsurrounding nematic through anisotropic molecular interactions at its surface.\nDroplets without swimming bacteria show no net displacement. The trajectory of\nthe active droplet can be predesigned as rectilinear or curvilinear by\npatterning the molecular orientation of the nematic medium. The effect\ndemonstrates that swimming at microscale can be achieved at the expense of\nbroken spatial symmetry of the medium; it can be used in development of\nmicromachines."
    },
    {
        "anchor": "High order nonlinear electrophoresis in a nematic liquid crystal: Electrophoresis is the motion of particles relative to a surrounding fluid\ndriven by a uniform electric field. In conventional electrophoresis, the\nelectrophoretic velocity grows linearly with the applied field. Nonlinear\neffects with a quadratic speed vs field dependence are gaining research\ninterest since an alternating current field could drive them. Here we report on\nthe giant nonlinearity of electrophoresis in a nematic liquid crystal in which\nthe speed grows with the fourth and sixth powers of the electric field. The\nmechanism is attributed to the shear thinning of the nematic environment\ninduced by the moving colloid. The observed giant nonlinear effect dramatically\nenhances the efficiency of electrophoretic transport.",
        "positive": "Competition between entropy and energy in network glass: the hidden\n  connection between intermediate phase and liquid-liquid transition: In network glass including chalcogenides, the network topology of microscopic\nstructures can be tuned by changing the chemical compositions. As the\ncomposition is varied, an intermediate phase (IP) singularly different from the\nadjacent floppy or rigid phases on sides has been revealed in the vicinity of\nthe rigidity onset of the network. Glass formers in the IP appear to be\nreversible at glass transition and strong in dynamical fragility. Meanwhile,\nthe calorimetry experiments indicate the existence of a first-order\nliquid-liquid transition (LLT) at a temperature above the glass transition in\nsome strong glass-forming liquids. How are the intermediate phase and the\nliquid-liquid transition related? Recent molecular dynamics simulations hint\nthat the intermediate phase is thermodynamically distinct that the transitions\nto IP as varying the chemical composition in fact reflect the LLT: out of IP,\nthe glass is frozen in vibrational entropy-dominated heterogeneous structures\nwith voids; while inside IP, energy dominates and the microscopic structures of\nliquids become homogeneous. Here we demonstrate such first-order thermodynamic\nliquid-liquid transition numerically and analytically in an elastic network\nmodel of network glass and discuss possible experimental approaches to testify\nthe connection."
    },
    {
        "anchor": "Drying Induced Hydrophobic Polymer Collapse: We have used computer simulation to study the collapse of a hydrophobic chain\nin water. We find that the mechanism of collapse is much like that of a first\norder phase transition. The evaporation of water in the vicinity of the polymer\nprovides the driving force for collapse, and the rate limiting step is the\nnucleation of a sufficiently large vapor bubble. The study is made possible\nthrough the application of transition path sampling and a coarse grained\ntreatment of liquid water. Relevance of our findings to understanding the\nfolding and assembly of proteins is discussed.",
        "positive": "Structural correlations and phase separation in binary mixtures of\n  charged and uncharged colloids: Structural correlations between colloids in a binary mixture of charged and\nuncharged spheres are calculated using computer simulations of the primitive\nmodel with explicit microions. For aqueous suspensions in a solvent of large\ndielectric constant, the traditional Derjaguin-Landau-Vervey-Overbeek (DLVO)\ntheory of linear screening, supplemented with hard core interactions,\nreproduces the structural correlations obtained in the full primitive model\nquantitatively. However for lower dielectric contrast, the increasing Coulomb\ncoupling between the micro- and macroions results in strong deviations. We find\na fluid-fluid phase separation into two regions either rich in charged or rich\nin uncharged particles which is not reproduced by DLVO theory. Our results are\nverifiable in scattering or real-space experiments on charged-uncharged\nmixtures of colloids or nanoparticles."
    },
    {
        "anchor": "Speckle-visibility spectroscopy: A tool to study time-varying dynamics: We describe a multispeckle dynamic light scattering technique capable of\nresolving the motion of scattering sites in cases that this motion changes\nsystematically with time. The method is based on the visibility of the speckle\npattern formed by the scattered light as detected by a single exposure of a\ndigital camera. Whereas previous multispeckle methods rely on correlations\nbetween images, here the connection with scattering site dynamics is made more\nsimply in terms of the variance of intensity among the pixels of the camera for\nthe specified exposure duration. The essence is that the speckle pattern is\nmore visible, i.e. the variance of detected intensity levels is greater, when\nthe dynamics of the scattering site motion is slow compared to the exposure\ntime of the camera. The theory for analyzing the moments of the spatial\nintensity distribution in terms of the electric field autocorrelation is\npresented. It is demonstrated for two well-understood samples, a colloidal\nsuspension of Brownian particles and a coarsening foam, where the dynamics can\nbe treated as stationary. However, the method is particularly appropriate for\nsamples in which the dynamics vary with time, either slowly or rapidly, limited\nonly by the exposure time fidelity of the camera. Potential applications range\nfrom soft-glassy materials, to granular avalanches, to flowmetry of living\ntissue.",
        "positive": "Sink-rise dynamics of horizontally oscillating active matter in granular\n  media: Theory: An intermediate step to modelling behaviour of active matter is understanding\ninteractions of active objects (AOs) with inanimate matter, which often lead to\na range of rich behaviour. We present a range of simulations of the interaction\nof a self-energised AO with three-dimensional granular matter and develop a\nfirst-principles theoretical model to describe the observed phenomena. The AO\noscillates horizontally, which causes it to either rise against gravity or\nsink, depending on the oscillation amplitude and frequency. We identify two\ncompeting mechanisms that drive the vertical motion. When the AO moves below a\ncritical speed, $v_c$, it generates a jammed stagnant zone ahead of it, which\neffects an upward force and leads to the rise. Above $v_c$ and certain kinetic\nenergy, the medium around the AO fluidises and the AO sinks into the layer\nsupporting it. The duration of the rising and sinking phases depend\nnon-trivially on the AO's amplitude and frequency leading to an intricate\nnonlinear dynamics. We derive the equation of motion for the time-dependent\ndepth from first-principles and show that its solutions agree well with a wide\nrange of computer simulations, which we perform within the range of parameters\nallowed by the finiteness of the simulated system."
    },
    {
        "anchor": "Influence of the Environment Fluctuations on Incoherent Neutron\n  Scattering Functions: In extending the conventional dynamic models, we consider a simple model to\naccount for the environment fluctuations of particle atoms in a protein system\nand derive the elastic incoherent structure factor (EISF) and the incoherent\nscattering correlation function C(Q,t) for both the jump dynamics between sites\nwith fluctuating site interspacing and for the diffusion inside a fluctuating\nsphere. We find that the EISF of the system (or the normalized elastic\nintensity) is equal to that in the absence of fluctuations averaged over the\ndistribution of site interspacing or sphere radius a. The scattering\ncorrelation function is $C(Q,t)=\\sum_{n}<{\\rm e}^{-\\lambda_n(a) t}> \\psi(t)$,\nwhere the average is taken over the Q-dependent effective distribution of\nrelaxation rates \\lambda_n(a) and \\psi(t) is the correlation function of the\nlength a. When \\psi(t)=1, the relaxation of C(Q,t) is exponential for the jump\ndynamics between sites (since \\lambda_n(a) is independent of a) while it is\nnonexponential for diffusion inside a sphere.",
        "positive": "Magnetic wire as stress controlled micro-rheometer for cytoplasm\n  viscosity measurements: We review here different methods to measure the bulk viscosity of complex\nfluids using micron-sized magnetic wires. The wires are characterized by length\nof a few microns and diameter of a few hundreds of nanometers. We first draw\nanalogies between cone-and-plate rheometry and wire-based microrheology. In\nparticular we highlight that magnetic wires can be operated as\nstress-controlled rheometers for two types of testing, the creep-recovery and\nsteady shear experiments. In the context of biophysical applications, the\ncytoplasm of different cell lines including fibroblasts, epithelial and tumor\ncells is studied. It reveals that the interior of living cells can be described\nas a viscoelastic liquid with a static viscosity comprised between 10 and 100\nPas. We extend the previous approaches and show that the proposed technique can\nalso provide time resolved viscosity data, which for cells display strong\ntemporal fluctuations. The present work demonstrates the high potential of the\nmagnetic wires for quantitative rheometry in confined espaces."
    },
    {
        "anchor": "Phase behavior of hard circular arcs: By using Monte Carlo numerical simulation, this work investigates the phase\nbehavior of systems of hard infinitesimally-thin circular arcs, from an\naperture angle $\\theta \\rightarrow 0$ to an aperture angle $\\theta \\rightarrow\n2 \\pi$, in the two-dimensional Euclidean space. Except in the isotropic phase\nat lower density and in the (quasi)nematic phase that solely forms for\nsufficiently small values of $\\theta$ and at intermediate values of density, in\nthe other phases that form, including the isotropic phase at higher density,\nhard infinitesimally-thin circular arcs auto-assemble to form clusters. These\nclusters are either filamentous, for smaller values of $\\theta$, or roundish,\nfor larger values of $\\theta$. Provided density is sufficiently high, the\nfilaments lengthen, merge and straighten to finally produce a filamentary phase\nwhile the roundels compact and dispose themselves with their centers of mass at\nthe sites of a triangular lattice to finally produce a cluster hexagonal phase.",
        "positive": "Stress Overshoots in Simple Yield Stress Fluids: Soft glassy materials such as mayonnaise, wet clays, or dense microgels\ndisplay under external shear a solid-to-liquid transition. Such a shear-induced\ntransition is often associated with a non-monotonic stress response, in the\nform of a stress maximum referred to as \"stress overshoot\". This ubiquitous\nphenomenon is characterized by the coordinates of the maximum in terms of\nstress $\\sigma_\\text{M}$ and strain $\\gamma_\\text{M}$ that both increase as\nweak power laws of the applied shear rate. Here we rationalize such power-law\nscalings using a continuum model that predicts two different regimes in the\nlimit of low and high applied shear rates. The corresponding exponents are\ndirectly linked to the steady-state rheology and are both associated with the\nnucleation and growth dynamics of a fluidized region. Our work offers a\nconsistent framework for predicting the transient response of soft glassy\nmaterials upon start-up of shear from the local flow behavior to the global\nrheological observables."
    },
    {
        "anchor": "Polar jets of swimming bacteria condensed by a patterned liquid crystal: Active matter exhibits remarkable collective behavior in which flows,\ncontinuously generated by active particles, are intertwined with the\norientational order of these particles. The relationship remains poorly\nunderstood as the activity and order are difficult to control independently.\nHere we demonstrate important facets of this interplay by exploring dynamics of\nswimming bacteria in a liquid crystalline environment with pre-designed\nperiodic splay and bend in molecular orientation. The bacteria are expelled\nfrom the bend regions and condense into polar jets that propagate and transport\ncargo unidirectionally along the splay regions. The bacterial jets remain\nstable even when the local concentration exceeds the threshold of bending\ninstability in a non-patterned system. Collective polar propulsion and\ndifferent role of bend and splay are explained by an advection-diffusion model\nand by numerical simulations that treat the system as a two-phase active\nnematic. The ability of prepatterned liquid crystalline medium to streamline\nthe chaotic movements of swimming bacteria into polar jets that can carry cargo\nalong a predesigned trajectory opens the door for potential applications in\ncell sorting, microscale delivery and soft microrobotics.",
        "positive": "Weakly nonlinear investigation of the Saffman-Taylor problem in a\n  rectangular Hele-Shaw cell: We analyze the Saffman-Taylor viscous fingering problem in rectangular\ngeometry. We investigate the onset of nonlinear effects and the basic\nsymmetries of the mode coupling equations, highlighting the link between\ninterface asymmetry and viscosity contrast. Symmetry breaking occurs through\nenhanced growth of sub-harmonic perturbations. Our results explain the absence\nof finger tip-splitting in the early flow stages, and saturation of growth\nrates compared with the predictions of linear stability."
    },
    {
        "anchor": "Statistics of Shear-induced Rearrangements in a Model Foam: Under steady shear, a foam relaxes stress through intermittent rearrangements\nof bubbles accompanied by sudden drops in the stored elastic energy. We use a\nsimple model of foam that incorporates both elasticity and dissipation to study\nthe statistics of bubble rearrangements in terms of energy drops, the number of\nnearest neighbor changes, and the rate of neighbor-switching (T1) events. We do\nthis for a two-dimensional system as a function of system size, shear rate,\ndissipation mechanism, and gas area fraction. We find that for dry foams, there\nis a well-defined quasistatic limit at low shear rates where localized\nrearrangements occur at a constant rate per unit strain, independent of both\nsystem size and dissipation mechanism. These results are in good qualitative\nagreement with experiments on two-dimensional and three-dimensional foams. In\ncontrast, we find for progessively wetter foams that the event size\ndistribution broadens into a power law that is cut off only by system size.\nThis is consistent with criticality at the melting transition.",
        "positive": "The Physics of Stratum Corneum Lipid Membranes: The Stratum Corneum (SC), the outermost layer of skin, comprises rigid\ncorneocytes (keratin filled dead cells) in a specialized lipid matrix. The\ncontinuous lipid matrix provides the main barrier against uncontrolled water\nloss and invasion of external pathogens. Unlike all other biological lipid\nmembranes (like intracellular organelles and plasma membranes), molecules in SC\nlipid matrix show small hydrophilic group and large variability in the length\nof the alkyl tails and in the numbers and positions of groups that are capable\nof forming hydrogen bonds. Molecular simulations provide a route for\nsystematically probing the effects of each of these differences separately. In\nthis article we present results from atomistic molecular dynamics of selected\nlipid bilayers and multilayers to probe the effect of these polydispersities.\nWe address the nature of the tail packing in the gel-like phase, the hydrogen\nbond network among head groups, the bending moduli expected for leaflets\ncomprising SC lipids, and the conformation of very long ceramide lipids (EOS)\nin multibilayer lipid assemblies."
    },
    {
        "anchor": "Theory of the dielectric susceptibility of liquid crystals with polar\n  nonuniaxial molecules: Statistical theory of the dielectric susceptibility of polar liquid crystals\nis proposed. The molecules are not uniaxial but similar to cones. It is assumed\nthat the permanent dipole moment of a molecule is parallel to the axis of the\nrotational symmetry. The ordering of the phase is described by means of the\nmean field theory based on the Maier-Saupe approach. The theory was used to\ncalculate the temperature dependence of the order parameters and the\nsusceptibilities. Predictions of the model for different sets of parameters are\ninvestigated.",
        "positive": "Adhesive contact mechanics of viscoelastic materials: In this study, we propose a theory of rough adhesive contact of viscoelastic\nmaterials in steady-state sliding. By exploiting a boundary formulation based\non Green function approach, the unknown contact domain is calculated by\nenforcing the local energy balance at the contact edge, thus considering also\nthe non-conservative work of internal stresses which is directly related to the\nodd part of the Green function. Theoretical predictions indicate that\nviscoelasticity may enhance the adhesive performance depending on the sliding\nvelocity, thus leading to larger contact area and pull-off force compared to\nthe equivalent adhesive elastic case The interplay between viscoelasticity and\nadhesion also affects the overall friction. Indeed, at low velocity, friction\nis strongly enhanced compared to the adhesiveless viscoelastic case, mainly due\nto the small-scale viscoelastic hysteresis induced by the adhesive neck close\nto the contact edge At higher velocity, the effect of viscoelastic hysteresis\noccurring at larger scales (bulk material) leads to even higher friction. Under\nthese conditions, in the presence of adhesion, the small-scale and large-scale\nviscoelastic contributions to friction cannot be separated. Finally, in\ncontrast with usual predictions for crack propagation/healing in infinite\nsystems, we found a non-monotonic trend of the energy release rates at the\ntrailing and leading contact edges, which is consistent with the finiteness of\nthe contact length. All the presented results are strongly supported by\nexisting experimental evidences."
    },
    {
        "anchor": "Selective and Collective Actuation in Active Solids: Active solids consist of elastically coupled out-of-equilibrium units\nperforming work. They are central to autonomous processes, such as locomotion,\nself-oscillations and rectification, in biological systems,designer materials\nand robotics. Yet, the feedback mechanism between elastic and active forces,\nand the possible emergence of collective behaviours in a mechanically stable\nelastic solid remains elusive. Here we introduce a minimal realization of an\nactive elastic solid, in which we characterize the emergence of selective and\ncollective actuation and fully map out the interplay between activity,\nelasticity and geometry. Polar active agents exert forces on the nodes of a two\ndimensional elastic lattice. The resulting displacement field nonlinearly\nreorients the active agents. For large enough coupling, a collective\noscillation of the lattice nodes around their equilibrium position emerges.\nOnly a few elastic modes are actuated and, crucially, they are not necessarily\nthe lowest energy ones. Combining experiments with the numerical and\ntheoretical analysis of an agents model, we unveil the bifurcation scenario and\nthe selection mechanism by which the collective actuation takes place. Our\nfindings may provide a new mechanism for oscillatory dynamics in biological\ntissues and specifically confluent cell monolayers. The present selection\nmechanism may also be advantageous in providing meta-materials, with bona fide\nautonomy.",
        "positive": "The viscosity-radius relationship for concentrated polymer solutions: A key assumption of polymer physics is that the random chains polymers extend\nin flow. Recent experimental evidence has shown that polymer chains compress in\nCouette flow in a manner counter to expectation. Here, scaling arguments\ndeveloped previously are used to determine the relationship between the\nviscosity and chain radius of gyration. Scaling arguments determine the\nviscosity-radius of gyration relationship to be such that the viscosity is\nproportional to the radius to the power of 9. The viscosity is shown to be a\npower law function of the radius, and to decrease with decreasing radius under\nconditions where the chains are ideal random walks in concentrated solution.\nFurthermore, this relationship is consistent with both the widely observed\nviscosity-temperature and viscosity-shear rate behavior observed in polymer\nrheology. The assumption of extension is not consistent with these observations\nas it would require that the chains increase in size with increasing\ntemperature. Shear thinning is thus a result of a decreasing radius with\nincreasing shear rate as the radius is proportional to the the shear rate\nraised to the power law exponent divided by 9. The thermal expansion\ncoefficient determines the variation in the power law exponents that are\nmeasured for different polymer systems. Typical values on n enable the measured\nreduction in coils size behavior to be fitted. Furthermore, the absurd notion\nthat polymer chains extend to reduce the viscosity implies that an increasing\nchain size results in a reduced viscosity is addressed. This assumption would\nrequire that the viscosity increases with reducing coil radius which is simply\nunphysical."
    },
    {
        "anchor": "On the properties of a single OPLS-UA model curcumin molecule in water,\n  methanol and dimethyl sulfoxide. Molecular dynamics computer simulation\n  results: The properties of model solutions consisting of a solute --- single curcumin\nmolecule in water, methanol and dimethyl sulfoxide solvents have been studied\nusing molecular dynamics (MD) computer simulations in the isobaric-isothermal\nensemble. The united atom OPLS force field (OPLS-UA) model for curcumin\nmolecule proposed by us recently [J. Mol. Liq., 2016, 223, 707] in combination\nwith the SPC/E water, and the OPLS-UA type models for methanol and dimethyl\nsulfoxide have been applied. We have described changes of the internal\nstructure of the solute molecule induced by different solvent media in very\ndetail. The pair distribution functions between particular fragments of a\nsolute molecule with solvent particles have been analyzed. Statistical features\nof the hydrogen bonding between different species were explored. Finally, we\nhave obtained a self-diffusion coefficient of curcumin molecules in three model\nsolvents.",
        "positive": "Coefficient of restitution of a linear dashpot on a rigid surface: The linear dashpot model is applied to a single ball bouncing on a rigid\nsurface. It is shown that when gravity is included the coefficient of\nrestitution depends on impact velocity, in contrast to previous work that\nignored the effects of gravity. This velocity dependence is most pronounced at\nlow impact velocities and high damping. Previous work has considered the ball\nto be in contact with the floor when the compression is nonzero, while other\nanalysis terminates the collision earlier, to prevent an attractive force. We\ncompare these models and propose a hybrid between the two. The hybrid model is\nsuccessful in reproducing experimental results for a cart bouncing repeatedly\non a spring."
    },
    {
        "anchor": "Breakdown of diffusivity-entropy scaling in colloidal glass forming\n  liquids: Glass is a liquid that has lost its ability to flow. Why this particular\nsubstance undergoes its dramatic slowing down in kinetics while remaining\nbarely distinguishable in structure from the fluid state upon cooling\nconstitutes the central question of glass transition physics. Here, we\nexperimentally tested the pathway of kinetic slowing down in\nglass$\\textrm{-}$forming liquids that consisted of ellipsoidal or binary\nspherical colloids. In contrast to rotational motion, the exponential scaling\nbetween diffusion coefficient and excess entropy in translational motion was\nrevealed to break down at startlingly low area fractions ($\\phi_\\textrm{T}$)\ndue to glassy effects. At $\\phi_\\textrm{T}$, anormalous translation-rotation\ncoupling was enhanced and the topography of the free energy landscape became\nrugged. Basing on the positive correlation between $\\phi_\\textrm{T}$ and\nfragility, the measurement of $\\phi_\\textrm{T}$ offers a novel method for\npredicting liquids' relaxation while circumventing the prohibitive increase in\nequilibrium times required in high density regions. Our results highlight the\nrole that thermodynamical entropy plays in glass transitions.",
        "positive": "Biaxial extensional viscous dissipation in sheets expansion formed by\n  impact of drops of Newtonian and non-Newtonian fluids: We investigate freely expanding liquid sheets made of either simple Newtonian\nfluids or solutions of high molecular water-soluble polymer chains. A sheet is\nproduced by the impact of a drop on a quartz plate covered with a thin layer of\nliquid nitrogen that suppresses shear viscous dissipation thanks to an inverse\nLeidenfrost effect. The sheet expands radially until reaching a maximum\ndiameter and subsequently recedes. Experiments indicate the presence of two\nexpansion regimes: the capillary regime, where the maximum expansion is\ncontrolled by surface tension forces and does not depend on the viscosity, and\nthe viscous regime, where the expansion is reduced with increasing viscosity.\nIn the viscous regime, the sheet expansion for polymeric samples is strongly\nenhanced as compared to that of Newtonian samples with comparable zero-shear\nviscosity. We show that data for Newtonian and non-Newtonian fluids collapse on\na unique master curve where the maximum expansion factor is plotted against the\nrelevant effective biaxial extensional Ohnesorge number that depends on fluid\ndensity, surface tension and the biaxial extensional viscosity. For Newtonian\nfluids, this biaxial extensional viscosity is six times the shear viscosity. By\ncontrast, for the non- Newtonian fluids, a characteristic Weissenberg\nnumber-dependent biaxial extensional viscosity is identified, which is in\nquantitative agreement with experimental and theoretical results reported in\nthe literature for biaxial extensional flows of polymeric liquids."
    },
    {
        "anchor": "The role of local bond-order at crystallization in a simple supercooled\n  liquid: Large scale Molecular Dynamics simulations of sixty-five systems with N=80000\nLennard-Jones particles at two different supercooled liquid state points\nreveals, that the supercooled states contain spatially heterogeneous\ndistributed subdomains of particles with significant higher bond-order than the\nmean bond-order in the supercooled liquid. The onset of crystallization starts\nin such an area with relative high six-ford bond-order for a supercooled state,\nbut low bond-order for a fcc crystal. The critical nucleus of N \\approx 70\nparticles is surrounded by many hundred of particles with relative high\nsupercooled liquid bond-order and many of these particles are aligned with the\ncrystal ordered particles in the critical nucleus. The crystallizations are\nvery fast and supported by a fast growth of the supercooled areas with relative\nhigh liquid bond-order. The crystallization are to fcc crystals, but with\nsignificant part of the crystallizations exhibit five fold arrangements of\npolycrystalline subdomains mainly with fcc crystal order and sign of hcp\ncrystallites.",
        "positive": "Simulations of Helix Unwinding in Ferroelectric Liquid Crystals: In bulk ferroelectric liquid crystals, the molecular director twists in a\nhelix. In narrow cells, this helix can be unwound by an applied electric field\nor by boundary effects. To describe helix unwinding as a function of both\nelectric field and boundary effects, we develop a mesoscale simulation model\nbased on a continuum free energy discretized on a two-dimensional lattice. In\nthese simulations, we determine both the director profile across the cell and\nthe net electrostatic polarization. By varying the cell size, we show how\nboundary effects shift the critical field for helix unwinding and lower the\nsaturation polarization. Our results are consistent with experimental data."
    },
    {
        "anchor": "The viscosities of partially molten materials undergoing diffusion creep: Partially molten materials resist shearing and compaction. This resistance is\ndescribed by a fourth-rank effective viscosity tensor. When the tensor is\nisotropic, two scalars determine the resistance: an effective shear and an\neffective bulk viscosity. Here, calculations are presented of the effective\nviscosity tensor during diffusion creep for a 2D tiling of hexagonal unit cells\nand a 3D tessellation of tetrakaidecahedrons (truncated octahedrons). The\ngeometry of the melt is determined by assuming textural equilibrium. The\nviscosity tensor for the 2D tiling is isotropic, but that for the 3D\ntessellation is anisotropic. Two parameters control the effect of melt on the\nviscosity tensor: the porosity and the dihedral angle. Calculations for both\nNabarro-Herring (volume diffusion) and Coble (surface diffusion) creep are\npresented. For Nabarro-Herring creep the bulk viscosity becomes singular as the\nporosity vanishes. This singularity is logarithmic, a weaker singularity than\ntypically assumed in geodynamic models. The presence of a small amount of melt\n(0.1% porosity) causes the effective shear viscosity to approximately halve.\nFor Coble creep, previous modelling work has argued that a very small amount of\nmelt may lead to a substantial, factor of 5, drop in the shear viscosity. Here,\na much smaller, factor of 1.4, drop is obtained for tetrakaidecahedrons. Owing\nto a Cauchy relation symmetry, the Coble creep bulk viscosity is a constant\nmultiple of the shear viscosity when melt is present.",
        "positive": "Roles of liquid structural ordering in glass transition,\n  crystallization, and water's anomalies: The liquid state is one of the fundamental and essential states of matter,\nbut its physical understanding is far behind the other states, such as the gas\nand solid states, due to the difficulties associated with the high density\ncausing many-body correlations and the lack of long-range order. Significant\nopen problems in liquid science include glass transition, crystallization, and\nwater's anomalies. Austen Angell has contributed tremendously to these problems\nand proposed many new concepts of fundamental importance. In this article, we\nreview how these concepts have influenced our work on liquid physics, focusing\non the roles of liquid structural ordering in glass transition,\ncrystallization, and water's anomalies."
    },
    {
        "anchor": "Selective molecular transport in thermo-responsive polymer membranes:\n  role of nanoscale hydration and fluctuations: For a wide range of modern soft functional materials the selective transport\nof sub-nanometer-sized molecules (`penetrants') through a stimuli-responsive\npolymeric membrane is key to the desired function. In this study, we\ninvestigate the diffusion properties of penetrants ranging from non-polar to\npolar molecules and ions in a matrix of collapsed Poly(N-isopropylacrylamide)\n(PNIPAM) polymers in water by means of extensive molecular dynamics\nsimulations. We find that the water distributes heterogeneously in fractal-like\ncluster structures embedded in the nanometer-sized voids of the polymer matrix.\nThe nano-clustered water acts as an important player in the penetrant\ndiffusion, which proceeds via a hopping mechanism through `wet' transition\nstates: the penetrants hop from one void to another via transient water\nchannels opened by rare but decisive polymer fluctuations. The diffusivities of\nthe studied penetrants extend over almost five orders of magnitude and thus\nenable a formulation of an analytical scaling relation with a clear\nnon-Stokesian, exponential dependence of the diffusion coefficient on the\npenetrant's radius for the uncharged penetrants. Charged penetrants (ions)\nbehave differently as they get captured in large isolated water clusters.\nFinally, we find large energetic activation barriers for hopping, which\nsignificantly depend on the hydration state and thereby challenge available\ntransport theories.",
        "positive": "Inertial dynamics of an active Brownian particle: Active Brownian motion commonly assumes spherical overdamped particles.\nHowever, self-propelled particles are often neither symmetric nor overdamped\nyet underlie random fluctuations from their surroundings. Active Brownian\nmotion has already been generalized to include asymmetric particles.\nSeparately, recent findings have shown the importance of inertial effects for\nparticles of macroscopic size or in low-friction environments. We aim to\nconsolidate the previous findings into the general description of a\nself-propelled asymmetric particle with inertia. We derive the Langevin\nequation of such a particle as well as the corresponding Fokker-Planck\nequation. Furthermore, a formula is presented that allows reconstructing the\nhydrodynamic resistance matrix of the particle by measuring its trajectory.\nNumerical solutions of the Langevin equation show that, independently of the\nparticle's shape, the noise-free trajectory at zero temperature starts with an\ninertial transition phase and converges to a circular helix. We discuss this\nuniversal convergence with respect to the helical motion that many\nmicroorganisms exhibit."
    },
    {
        "anchor": "From Molecular Dynamics to Dissipative Particle Dynamics: A procedure is introduced for deriving a coarse-grained dissipative particle\ndynamics from molecular dynamics. The rules of the dissipative particle\ndynamics are derived from the underlying molecular interactions, and a Langevin\nequation is obtained that describes the forces experienced by the dissipative\nparticles and specifies the associated canonical Gibbs distribution for the\nsystem.",
        "positive": "Recent advances in liquid mixtures in electric fields: When immiscible liquids are subject to electric fields interfacial forces\narise due to a difference in the permittivity or the conductance of the\nliquids, and these forces lead to shape change in droplets or to interfacial\ninstabilities. In this Topical Review we discuss recent advances in the theory\nand experiments of liquids in electric fields with an emphasis on liquids which\nare initially miscible and demix under the influence of an external field. In\npurely dielectric liquids demixing occurs if the electrode geometry leads to\nsufficiently large field gradients. In polar liquids field gradients are\nprevalent due to screening by dissociated ions irrespective of the electrode\ngeometry. We examine the conditions for these \"electro prewetting\" transitions\nand highlight few possible systems where they might be important, such as in\nstabilization of colloids and in gating of pores in membranes."
    },
    {
        "anchor": "Microscopic theory of solvent mediated long range forces: influence of\n  wetting: We show that a general density functional approach for calculating the force\nbetween two big particles immersed in a solvent of smaller ones can describe\nsystems that exhibit fluid-fluid phase separation: the theory captures effects\nof strong adsorption (wetting) and of critical fluctuations in the solvent. We\nillustrate the approach for the Gaussian core model, a simple model of a\npolymer mixture in solution and find extremely attractive, long ranged solvent\nmediated potentials between the big particles for state points lying close to\nthe binodal, on the side where the solvent is poor in the species which is\nfavoured by the big particles.",
        "positive": "How does your gyroid grow?: A mesoatomic perspective on supramolecular,\n  soft matter network crystals: We propose a framework to understand supramolecular network crystals formed\nin soft matter in terms of mesoatomic building blocks, collective groupings of\namphiphilic molecules that play a role analogous to atomic or molecular\nsubunits of hard matter crystals. While the concept of mesoatoms is intuitive\nand widely invoked in crystalline arrangements of sphere- or cylinder-like\n(micelle-like) domains, analogous notions of physically meaningful building\nblocks of triply periodic network crystals, like the double-gyroid or\ndouble-diamond structures are obscured by the complex, bicontinuous domain\nshapes and intercatenated topologies of the double networks. Focusing on the\nexample of diblock copolymer melts, we propose generic rules for decomposing\ntriply-periodic network crystals into a unique set of mesoatomic building\nblocks, leading to mesoatomic volumes that are non-convex and bound by smoothly\ncurved faces, unlike the more familiar polyhedral shapes associated with\nsphere- and cylinder-like mesoatoms. We analyze the shapes of these mesoatoms,\ntheir internal structure and importantly their local packing with neighbor\nmesoatomic units. Hypothesizing that mesoatoms are kinetically favored\nintermediate structures whose local shapes and packing template network crystal\nassembly on long time scales, we propose and study a minimal energetic model of\nmesoatom assembly for three different cubic double-network crystals, which\npredicts a detailed picture for kinetics of intercatenation and surface growth.\nWe discuss potential extensions and elaborations of the mesoatomic description\nof supramolecular soft matter network crystals, experimental observations of\nmalleable mesoatomic units in the precursor sponge phase as well as in ordered\ncubic networks, as well as possibilities for observing mesoatoms in primordial,\npre-crystalline states."
    },
    {
        "anchor": "Kohn anomalies and non-adiabaticity in doped carbon nanotubes: The high-frequency Raman-active phonon modes of metallic single-walled carbon\nnanotubes (SWNTs) are thought to be characterized by Kohn anomalies (KAs),\nwhich are expected to be modified by the doping-induced tuning of the Fermi\nenergy level $\\epsilon_F$, obtained through the intercalation of SWNTs with\nalkali atoms or by the application of a gate potential. We present a\nDensity-Functional Theory (DFT) study of the phonon properties of a (9,9)\nmetallic SWNT as a function of electronic doping. For such study, we use, as in\nstandard DFT calculations of vibrational properties, the Born-Oppenheimer (BO)\napproximation. We also develop an analytical model capable of reproducing and\ninterpreting our DFT results. Both DFT calculations and this model predict, for\nincreasing doping levels, a series of EPC-induced KAs in the vibrational mode\nparallel to the tube axis at the $\\mathbf\\Gamma$ point of the Brillouin zone,\nusually indicated in Raman spectroscopy as the $G^-$ peak. Such KAs would arise\neach time a new conduction band is populated. However, we show that they are an\nartifact of the BO approximation. The inclusion of non-adiabatic (NA) effects\ndramatically affects the results, predicting KAs at $\\mathbf\\Gamma$ only when\n$\\epsilon_F$ is close to a band crossing $E_{X}$. For each band crossing a\ndouble KA occurs for $\\epsilon_F=E_{X}\\pm \\hbar\\omega/2$, where $\\hbar\\omega$\nis the phonon energy. In particular, for a 1.2 $nm$ metallic nanotube, we\npredict a KA to occur in the so-called $G^-$ peak at a doping level of about\n$N_{el}/C=\\pm 0.0015$ atom ($\\epsilon_F\\approx \\pm 0.1 ~eV$). Furthermore, we\npredict that the Raman linewidth of the $G^-$ peak significantly decreases for\n$|\\epsilon_F| \\geq \\hbar\\omega/2$.",
        "positive": "Heirarchical Self Assembly: Self Organized nano-structures in a\n  nematically ordered matrix of self assembled polymeric chains: We report many different nano-structures which are formed when model\nnano-particles of different sizes (diameter {\\sigma} n ) are allowed to\naggregate in a background matrix of semi-flexible self assembled polymeric worm\nlike micellar chains. The different nano-structures are formed by the dynamical\narrest of phase-separating mixtures of micellar monomers and nano-particles.\nThe different mor- phologies obtained are the result of an interplay of the\navailable free volume, the elastic energy of deformation of polymers, the\ndensity (chemical potential) of the nano-particles in the polymer ma- trix and,\nof course, the ratio of the size of self assembling nano-particles and self\navoidance diameter of polymeric chains. We have used a hybrid semi-grand\ncanonical Monte Carlo simulation scheme to obtain the (non-equilibrium) phase\ndiagram of the self-assembled nano-structures. We observe rod-like structures\nof nano-particles which get self assembled in the gaps between the nematically\nordered chains as well as percolating gel-like network of conjoined nanotubes.\nWe also find a totally unexpected interlocked crystalline phase of\nnano-particles and monomers, in which each crytal plane of nanoparticles is\nseparated by planes of perfectly organized polymer chains. We identified the\ncon- dition which leads to such interlocked crystal structure. We suggest\nexperimental possibilities of how the results presented in this paper could be\nused to obtain different nano-structures in the lab."
    },
    {
        "anchor": "Resistances for heat and mass transfer through a liquid-vapor interface\n  in a binary mixture: In this paper we calculate the interfacial resistances to heat and mass\ntransfer through a liquid-vapor interface in a binary mixture. We use two\nmethods, the direct calculation from the actual non-equilibrium solution and\nintegral relations, derived earlier. We verify, that integral relations, being\na relatively faster and cheaper method, indeed gives the same results as the\ndirect processing of a non-equilibrium solution. Furthermore we compare the\nabsolute values of the interfacial resistances with the ones obtained from\nkinetic theory. Matching the diagonal resistances for the binary mixture we\nfind that kinetic theory underestimates the cross coefficients. The heat of\ntransfer is as a consequence correspondingly larger.",
        "positive": "Robust Scaling of Strength and Elastic Constants and Universal\n  Cooperativity in Disordered Colloidal Micropillars: We study the uniaxial compressive behavior of disordered colloidal\nfree-standing micropillars composed of a bidisperse mixture of 3 and 6 um\npolystyrene particles. Mechanical annealing of confined pillars enables\nvariation of the packing fraction across the phase space of colloidal glasses.\nThe measured normalized strengths and elastic moduli of the annealed\nfreestanding micropillars span almost three orders-of-magnitude despite similar\nplastic morphology governed by shear banding. We measure a robust correlation\nbetween ultimate strengths and elastic constants that is invariant to relative\nhumidity, implying a critical strain of $\\sim$0.01 that is strikingly similar\nto that observed in metallic glasses (MGs) [W.L. Johnson, K. Samwer, Phys. Rev.\nLett. 95, 195501, 2005] and suggestive of a universal mode of cooperative\nplastic deformation. We estimate the characteristic strain of the underlying\ncooperative plastic event by considering the energy necessary to create an\nEshelby-like ellipsoidal inclusion in an elastic matrix. We find that the\ncharacteristic strain is similar to that found in experiments and simulations\nof other disordered solids with distinct bonding and particle sizes, suggesting\na universal criterion for the elastic to plastic transition in glassy materials\nwith the capacity for finite plastic flow."
    },
    {
        "anchor": "Pair correlation functions in nematics, free-energy functional and\n  isotropic-nematic transition: We develop a free energy functional for an inhomogeneous system that contains\nboth symmetry conserved and symmetry broken parts of the direct pair\ncorrelation function. These correlation functions are found by solving the\nOrnstein- Zernike equation with the Percus-Yevick closure relation. The method\ndeveloped here gives the pair correlation functions in the ordered phase with\nfeatures that agree well with the results found by computer simulations. The\ntheory predicts accurately the isotropic-nematic transition in a system of\nanisotropic molecules and can easily be extended to study other ordered phases\nsuch as smectics and crystalline solids.",
        "positive": "Phonons and elasticity in critically coordinated lattices: Much of our understanding of vibrational excitations and elasticity is based\nupon analysis of frames consisting of sites connected by bonds occupied by\ncentral-force springs, the stability of which depends on the average number of\nneighbors per site $z$. When $z<z_c \\approx 2d$, where $d$ is the spatial\ndimension, frames are unstable with respect to internal deformations. This\npedagogical review focuses on properties of frames with $z$ at or near $z_c$,\nwhich model systems like randomly packed spheres near jamming and network\nglasses. Using an index theorem, $N_0 - N_S = dN - N_B$ relating the number of\nsites, $N$, and number of bonds, $N_B$, to the number, $N_0$, of modes of zero\nenergy and the number, $N_S$, of states of self stress, in which springs can be\nunder positive or negative tension while forces on sites remain zero, it\nexplores the properties of periodic square, kagome, and related lattices for\nwhich $z=z_c$ and the relation between states of self stress and zero modes in\nperiodic lattices to the surface zero modes of finite free lattices (with free\nboundary conditions). It shows how modifications to the periodic kagome lattice\ncan eliminate all but trivial translational zero modes and create topologically\ndistinct classes, analogous to those of topological insulators, with protected\nzero modes at free boundaries and at interfaces between different topological\nclasses."
    },
    {
        "anchor": "Asymmetric Coulomb fluids at randomly charged dielectric interfaces:\n  Anti-fragility, overcharging and charge inversion: We study the distribution of multivalent counterions next to a dielectric\nslab, bearing a quenched, random distribution of charges on one of its solution\ninterfaces, with a given mean and variance, both in the absence and in the\npresence of a bathing monovalent salt solution. We use the previously derived\napproach based on the dressed multivalent-ion theory that combines aspects of\nthe strong and weak coupling of multivalent and monovalent ions in a single\nframework. The presence of quenched charge disorder on the charged surface of\nthe dielectric slab is shown to substantially increase the density of\nmultivalent counterions in its vicinity. In the counterion-only model (with no\nmonovalent salt ions), the surface disorder generates an additional logarithmic\nattraction potential and thus an algebraically singular counterion density\nprofile at the surface. This behavior persists also in the presence of a\nmonovalent salt bath and results in significant violation of the contact-value\ntheorem, reflecting the anti-fragility effects of the disorder that drive the\nsystem towards a more ordered state. In the presence of an interfacial\ndielectric discontinuity, depleting the counterion layer at the surface, the\ncharge disorder still generates a much enhanced counterion density further away\nfrom the surface. Likewise, the charge inversion and/or overcharging of the\nsurface occur more strongly and at smaller bulk concentrations of multivalent\ncounterions when the surface carries quenched charge disorder. Overall, the\npresence of quenched surface charge disorder leads to sizable effects in the\ndistribution of multivalent counterions in a wide range of realistic parameters\nand typically within a distance of a few nanometers from the charged surface.",
        "positive": "Anomalous dynamics of interstitial dopants in soft crystals: The dynamics of interstitial dopants governs the properties of a wide variety\nof doped crystalline materials. To describe the hopping dynamics of such\ninterstitial impurities, classical approaches often assume that dopant\nparticles do not interact and travel through a static potential energy\nlandscape. Here we show, using computer simulations, how these assumptions and\nthe resulting predictions from classical Eyring-type theories break down in\nentropically-stabilised BCC crystals due to the thermal excitations of the\ncrystalline matrix. Deviations are particularly severe close to melting where\nthe lattice becomes weak and dopant dynamics exhibit strongly localised and\nheterogeneous dynamics. We attribute these anomalies to the failure of both\nassumptions underlying the classical description: i) the instantaneous\npotential field experienced by dopants becomes largely disordered due to\nthermal fluctuations and ii) elastic interactions cause strong dopant-dopant\ninteractions even at low doping fractions. These results illustrate how\ndescribing non-classical dopant dynamics requires taking the effective\ndisordered potential energy landscape of strongly excited crystals and\ndopant-dopant interactions into account."
    },
    {
        "anchor": "Structure and stability of helices in square-well homopolymers: Recently, it has been demonstrated [Magee et al., Phys. Rev. Lett. 96, 207802\n(2006)] that isolated, square-well homopolymers can spontaneously break chiral\nsymmetry and freeze into helical structures at sufficiently low temperatures.\nThis behavior is interesting because the square-well homopolymer is itself\nachiral. In this work, we use event-driven molecular dynamics, combined with an\noptimized parallel tempering scheme, to study this polymer model over a wide\nrange of parameters. We examine the conditions where the helix structure is\nstable and determine how the interaction parameters of the polymer govern the\ndetails of the helix structure. The width of the square well (proportional to\nlambda) is found to control the radius of the helix, which decreases with\nincreasing well width until the polymer forms a coiled sphere for sufficiently\nlarge wells. The helices are found to be stable for only a window of molecular\nweights. If the polymer is too short, the helix will not form. If the polymer\nis too long, the helix is no longer the minimum energy structure, and other\nfolded structures will form. The size of this window is governed by the chain\nstiffness, which in this model is a function of the ratio of the monomer size\nto the bond length. Outside this window, the polymer still freezes into a\nlocked structure at low temperature, however, unless the chain is sufficiently\nstiff, this structure will not be unique and is similar to a glassy state.",
        "positive": "Packing in Protein Cores: Proteins are biological polymers that underlie all cellular functions. The\nfirst high-resolution protein structures were determined by x-ray\ncrystallography in the 1960s. Since then, there has been continued interest in\nunderstanding and predicting protein structure and stability. It is\nwell-established that a large contribution to protein stability originates from\nthe sequestration from solvent of hydrophobic residues in the protein core. How\nare such hydrophobic residues arranged in the core? And how can one best model\nthe packing of these residues? Here we show that to properly model the packing\nof residues in protein cores it is essential that amino acids are represented\nby appropriately calibrated atom sizes, and that hydrogen atoms are explicitly\nincluded. We show that protein cores possess a packing fraction of $\\phi\n\\approx 0.56$, which is significantly less than the typically quoted value of\n0.74 obtained using the extended atom representation. We also compare the\nresults for the packing of amino acids in protein cores to results obtained for\njammed packings from disrete element simulations composed of spheres, elongated\nparticles, and particles with bumpy surfaces. We show that amino acids in\nprotein cores pack as densely as disordered jammed packings of particles with\nsimilar values for the aspect ratio and bumpiness as found for amino acids.\nKnowing the structural properties of protein cores is of both fundamental and\npractical importance. Practically, it enables the assessment of changes in the\nstructure and stability of proteins arising from amino acid mutations (such as\nthose identified as a result of the massive human genome sequencing efforts)\nand the design of new folded, stable proteins and protein-protein interactions\nwith tunable specificity and affinity."
    },
    {
        "anchor": "Specific Salt Effects on Thermophoresis of Charged Colloids: We study the Soret effect of charged polystyrene particles as a function of\ntemperature and electrolyte composition. As a main result we find that the\nSoret coefficient is determined by charge effects, and that non-ionic\ncontributions are small. In view of the well-kown electric-double layer\ninteractions, our thermal field-flow fractionation data lead us to the\nconclusion that the Soret effect originates to a large extent from\ndiffusiophoresis in the salt gradient and from the electrolyte Seebeck effect,\nboth of which show strong specific-ion effects. Moreover, we find that\nthermophoresis of polystyrene beads is fundamentally different from proteins\nand aqueous polymer solutions, which show a strong non-ionic contribution.",
        "positive": "Soft Metamaterials: Adaptation and Intelligence: We provide a perspective on soft metamaterials and biomatter with a special\nemphasis on future research directions at the interface between material\nintelligence and adaptation."
    },
    {
        "anchor": "Transport of the moving barrier driven by chiral active particles: Transport of a moving V-shaped barrier exposed to a bath of chiral active\nparticles is investigated in a two-dimensional channel. Due to the chirality of\nactive particles and the transversal asymmetry of the barrier position, active\nparticles can power and steer the directed transport of the barrier in the\nlongitudinal direction. The transport of the barrier is determined by the\nchirality of active particles. The moving barrier and active particles move in\nthe opposite directions. The average velocity of the barrier is much larger\nthan that of active particles. There exist optimal parameters (the chirality,\nthe self-propulsion speed, the packing fraction, and the channel width) at\nwhich the average velocity of the barrier takes its maximal value. In\nparticular, tailoring the geometry of the barrier and the active concentration\nprovides novel strategies to control the transport properties of micro-objects\nor cargoes in an active medium.",
        "positive": "Thermodynamic and topological properties of copolymer rings with a\n  segregation/mixing transition: Two ring polymers close to each other in space may be either in a segregated\nphase if there is a strong repulsion between monomers in the polymers, or\nintermingle in a mixed phase if there is a strong attractive force between the\nmonomers. These phases are separated by a critical point which has a\n$\\theta$-point character. The metric and topological properties of the ring\npolymers depend on the phase, and may change abruptly at the critical point. In\nthis paper we examine the thermodynamics and linking of two ring polymers close\nin space in both the segregated and mixed phases using a cubic lattice model of\ntwo polygons interacting with each other. Our results show that the probability\nof linking is low in the segregated phase, but that it increases through the\ncritical point as the model is taken into the mixed phase. We also examine the\nmetric and thermodynamic properties of the model, with focus on how the\naveraged measures of topological complexity are related to these properties."
    },
    {
        "anchor": "Inertial migration of a deformable capsule in an oscillatory flow in a\n  microchannel: Dynamics of a deformable capsule in an oscillatory flow of a Newtonian fluid\nin a microchannel has been studied numerically. The effects of oscillation\nfrequency, capsule deformability, and channel flow rate have been explored by\nsimulating the capsule within a microchannel. In addition, the simulation\ncaptures the effect of the type of imposed pressure oscillations on the\nmigration pattern of the capsule. An oscillatory channel flow enables the\nfocusing of extremely small biological particles by eliminating the need to\ndesign impractically long channels. The presented results show that the\nequilibrium position of the capsule changes not only by the addition of an\noscillatory component to the pressure gradient, but it also is influenced by\nthe capsule deformability and channel flow rate. Furthermore, it has been shown\nthat the amplitude of oscillation of capsules decreases as the channel flow\nrate and the rigidity of the capsule increases.",
        "positive": "Impact of grain properties on the penetration of intruders near a wall\n  into granular matter: a DEM study: DEM simulations were used to study the sensitivity of a granular system to\nthe change of the mechanical properties of the grains, applied to the\npenetration of a cylindrical intruder near a vertical wall. The simulations\nreproduce a real experimental setup, changing the friction, the Young modulus\nand the restitution coefficient of the particles."
    },
    {
        "anchor": "Asymmetric bistability of chiral particle orientation in viscous shear\n  flows: The migration of helical particles in viscous shear flows plays a crucial\nrole in chiral particle sorting. Attaching a non-chiral head to a helical\nparticle leads to a rheotactic torque inducing particle reorientation. This\nphenomenon is responsible for bacterial rheotaxis observed for flagellated\nbacteria as Escherichia coli in shear flows. Here we use a high-resolution\nmicroprinting technique to fabricate micro-particles with controlled and\ntunable chiral shape consisting of a spherical head and helical tails of\nvarious pitch and handedness. By observing the fully time-resolved dynamics of\nthese micro-particles in microfluidic channel flow, we gain valuable insights\ninto chirality-induced orientation dynamics. Our experimental model system\nallows us to examine the effects of particle elongation, chirality, and\nhead-heaviness for different flow rates on the orientation dynamics, while\nminimizing the influence of Brownian noise. Through our model experiments we\ndemonstrate the existence of asymmetric bistability of the particle orientation\nperpendicular to the flow direction. We quantitatively explain the particle\nequilibrium orientations as a function of particle properties, initial\nconditions and flow rates, as well as the time-dependence of the reorientation\ndynamics through a theoretical model. The model parameters are determined using\nboundary element simulations and excellent agreement with experiments is\nobtained without any adjustable parameters. Our findings lead to a better\nunderstanding of chiral particle transport, bacterial rheotaxis and might allow\nthe development of targeted delivery applications.",
        "positive": "Active volatile drops on liquid baths: In most experimental studies, active drops propel in a liquid bulk due to\nself-generated interfacial stresses of solutal origin. Here, we demonstrate the\nself-propulsion of a volatile drop on the surface of a liquid bath due to\nstresses of thermal origin. Evaporative heat pumping is converted into directed\nmotion driven by thermocapillary stresses, which emerge on the drop surface as\na result of a symmetry breaking of the drop temperature field. The dependence\nof the drop speed on the activity source, i.e. the evaporation flux, is derived\nwith scaling arguments and captures the experimental data."
    },
    {
        "anchor": "Self-assembly mechanism in colloids: perspectives from Statistical\n  Physics: Motivated by recent experimental findings in chemical synthesis of colloidal\nparticles, we draw an analogy between self-assembly processes occurring in\nbiological systems (e.g. protein folding) and a new exciting possibility in the\nfield of material science. We consider a self-assembly process whose elementary\nbuilding blocks are decorated patchy colloids of various types, that\nspontaneously drive the system toward a unique and predetermined targeted\nmacroscopic structure.\n  To this aim, we discuss a simple theoretical model -- the Kern-Frenkel model\n-- describing a fluid of colloidal spherical particles with a pre-defined\nnumber and distribution of solvophobic and solvophilic regions on their\nsurface. The solvophobic and solvophilic regions are described via a\nshort-range square-well and a hard-sphere potentials, respectively.\n  Integral equation and perturbation theories are presented to discuss\nstructural and thermodynamical properties, with particular emphasis on the\ncomputation of the fluid-fluid (or gas-liquid) transition in the\ntemperature-density plane.\n  The model allows the description of both one and two attractive caps, as a\nfunction of the fraction of covered attractive surface, thus interpolating\nbetween a square-well and a hard-sphere fluid, upon changing the coverage.\n  By comparison with Monte Carlo simulations, we assess the pros and the cons\nof both integral equation and perturbation theories in the present context of\npatchy colloids, where the computational effort for numerical simulations is\nrather demanding.",
        "positive": "A model for hierarchical patterns under mechanical stresses: We present a model for mechanically-induced pattern formation in growing\nbiological tissues and discuss its application to the development of leaf\nvenation networks. Drawing an analogy with phase transitions in solids, we use\na phase field method to describe the transition between two states of the\ntissue, e.g. the differentiation of leaf veins, and consider a layered system\nwhere mechanical stresses are generated by differential growth. We present\nanalytical and numerical results for one-dimensional systems, showing that a\ncombination of growth and irreversibility gives rise to hierarchical patterns.\nTwo-dimensional simulations suggest that such a mechanism could account for the\nhierarchical, reticulate structure of leaf venation networks, yet point to the\nneed for a more detailed treatment of the coupling between growth and\nmechanical stresses."
    },
    {
        "anchor": "Contrasting bending energies from bulk elastic theories: The choice of elastic energies for thin plates and shells is an unsettled\nissue with consequences for much recent modeling of soft matter. Through\nconsideration of simple deformations of a thin body in the plane, we\ndemonstrate that four bulk isotropic quadratic elastic theories have\nfundamentally different predictions with regard to bending behavior. At finite\nthickness, these qualitative effects persist near the limit of mid-surface\nisometry, and not all theories predict an isometric ground state. We discuss\nhow certain kinematic measures that arose in early studies of rod mechanics\nlead to coherent definitions of stretching and bending, and promote the\nadoption of these quantities in the development of a covariant theory based on\nstretches rather than metrics.",
        "positive": "Viral nematics in confined geometries: Motivated by recent experiments on the rod-like virus bacteriophage fd,\nconfined to circular and annular domains, we present a theoretical study of\nstructural transitions in these geometries. Using the continuum theory of\nnematic liquid crystals, we examine the competition between bulk elasticity and\nsurface anchoring, mediated by the formation of topological defects. We show\nanalytically that bulk defects are unstable with respect to defects sitting at\nthe boundary. Moreover, in case of an annulus, whose topology does not require\nthe presence of topological defects, under weak anchoring conditions we find\nthat nematic textures with boundary defects are stable compared to the defect\nfree configurations. Thus our simple approach, with no fitting parameters,\nsuggests a possible symmetry breaking mechanism responsible for the formation\nof one-, two- and three-fold textures under annular confinement."
    },
    {
        "anchor": "Thermodynamic Properties of the van der Waals Fluid: The van der Waals (vdW) theory of fluids is the first and simplest theory\nthat takes into account interactions between the particles of a system that\nresult in a phase transition versus temperature. Combined with Maxwell's\nconstruction, this mean-field theory predicts the conditions for equilibrium\ncoexistence between the gas and liquid phases and the first-order transition\nbetween them. However, important properties of the vdW fluid have not been\nsystematically investigated. Here we report a comprehensive study of these\nproperties. Ambiguities about the physical interpretation of the Boyle\ntemperature and the influence of the vdW molecular interactions on the pressure\nof the vdW gas are resolved. Thermodynamic variables and properties are\nformulated in reduced units that allow all properties to be expressed as laws\nof corresponding states that apply to all vdW fluids. Lekner's parametric\nsolution for the vdW gas-liquid coexistence curve in the pressure-temperature\nplane and related thermodynamic properties [Am. J. Phys. 50, 161 (1982)] is\nexplained and significantly extended. Hysteresis in the first-order transition\ntemperature on heating and cooling is examined and the maximum degrees of\nsuperheating and supercooling determined. The latent heat of vaporization and\nthe entropy change on crossing the coexistence curve are investigated. The\ntemperature dependences of the isothermal compressibility, thermal expansion\ncoefficient and heat capacity at constant pressure for a range of pressures\nabove, at and below the critical pressure are systematically studied from\nnumerical calculations including their critical behaviors and their\ndiscontinuities on crossing the coexistence curve. Joule-Thomson expansion of\nthe vdW gas is investigated in detail and the pressure and temperature\nconditions for liquifying a vdW gas on passing through the throttle are\ndetermined.",
        "positive": "Microelectromagnets for Trapping and Manipulating Ultracold Atomic\n  Quantum Gases: We describe the production and characterization of microelectromagnets made\nfor trapping and manipulating atomic ensembles. The devices consist of 7\nfabricated parallel copper conductors 3 micrometer thick, 25mm long, with\nwidths ranging from 3 to 30 micrometer, and are produced by electroplating a\nsapphire substrate. Maximum current densities in the wires up to 6.5 * 10^6 A /\ncm^2 are achieved in continuous mode operation. The device operates\nsuccessfully at a base pressure of 10^-11 mbar. The microstructures permit the\nrealization of a variety of magnetic field configurations, and hence provide\nenormous flexibility for controlling the motion and the shape of Bose-Einstein\ncondensates."
    },
    {
        "anchor": "Three-site quantum lattice with thermal bath: An algorithm to simulate the dynamics of a quantum state over a three-site\nlattice interacting with classical harmonic oscillators has been devised.\n  The oscillators are linearly coupled to the quantum state and are acted upon\nby a fluctuation-dissipation process to take the equilibrium thermal\nenvironment into account, thus allowing to investigate how stochastic forces\nmay affect the quantum dynamics.\n  The implementation of the algorithm has been written in Ada95.",
        "positive": "Liquid crystal director fields in three-dimensional non-Euclidean\n  geometries: This paper investigates nematic liquid crystals in three-dimensional curved\nspace, and determines which director deformation modes are compatible with each\npossible type of non-Euclidean geometry. Previous work by Sethna et al. showed\nthat double twist is frustrated in flat space $R^3$, but can fit perfectly in\nthe hypersphere $S^3$. Here, we extend that work to all four deformation modes\n(splay, twist, bend, and biaxial splay) and all eight Thurston geometries. Each\npure mode of director deformation can fill space perfectly, for at least one\ntype of geometry. This analysis shows the ideal structure of each deformation\nmode in curved space, which is frustrated by the requirements of flat space."
    },
    {
        "anchor": "Phase Diagram for Self-assembly of Amphiphilic Molecule C12E6 by\n  Dissipative Particle Dynamics Simulation: In a previous study, dissipative particle dynamics simulation was used to\nqualitatively clarify the phase diagram of the amphiphilic molecule\nhexaethylene glycol dodecyl ether (C12E6). In the present study, the\nhydrophilicity dependence of the phase structure was clarified qualitatively by\nvarying the interaction potential between hydrophilic molecules and water\nmolecules in a dissipative particle dynamics (DPD) simulation using the Jury\nmodel. By varying the coefficient of the interaction potential $x$ between\nhydrophilic beads and water molecules as x=-20, 0, 10, and 20, at a\ndimensionless temperature of T=0.5 and a concentration of amphiphilic molecules\nin water of phi=50% the phase structures grew to lamellar (x=-20), hexagonal\n(x=0), and micellar (x=10) phases. For x=20, phase separation occurs between\nhydrophilic beads and water molecules.",
        "positive": "Clustering, conductor-insulator transition and phase separation of an\n  ultrasoft model of electrolytes: We investigate the clustering and phase separation of a model of ultrasoft,\noppositely charged macroions by a combination of Monte Carlo and Molecular\nDynamics simulations. Static and dynamic diagnostics, including the dielectric\npermittivity and the electric conductivity of the model, show that ion pairing\ninduces a sharp conductor-insulator transition at low temperatures and\ndensities, which impacts the separation into dilute and concentrated phases\nbelow a critical temperature. Preliminary evidence is presented for a possible\ntricritical nature of the phase diagram of the model."
    },
    {
        "anchor": "Discrete models of force chain networks: A fundamental property of any material is its response to a localized stress\napplied at a boundary. For granular materials consisting of hard, cohesionless\nparticles, not even the general form of the stress response is known. Directed\nforce chain networks (DFCNs) provide a theoretical framework for addressing\nthis issue, and analysis of simplified DFCN models reveal both rich\nmathematical structure and surprising properties. We review some basic elements\nof DFCN models and present a class of homogeneous solutions for cases in which\nforce chains are restricted to lie on a discrete set of directions.",
        "positive": "Universal behaviors in the wrinkling transition of disordered membranes: The wrinkling transition experimentally identified by Mutz et al. [Phys. Rev.\nLett. 67, 923 (1991)] and then thoroughly studied by Chaieb et al. [Phys. Rev.\nLett. 96, 078101 (2006)] in partially polymerized lipid membranes is\nreconsidered. One shows that the features associated with this transition,\nnotably the various scaling behaviors of the height-height correlation\nfunctions that have been observed, are qualitatively and quantitatively well\ndescribed by a recent nonperturbative renormalization group (NPRG) approach to\nquenched disordered membranes by Coquand et al. [Phys. Rev E 97, 030102\n(2018)]. As these behaviors are associated with fixed points of RG\ntransformations they are universal and should also be observed in, e.g.,\ndefective graphene and graphene-like materials."
    },
    {
        "anchor": "Order-Disorder structural transition in a confined fluid: In this paper the amorphous/solid to disorder liquid structural phase\ntransitions of an anomalous confined fluid is analyzed using their local\nfractal dimension. The model is a system of particles interacting through a two\nlength scales potentials confined by two infinite plates. In the bulk, this\nfluid exhibit water-like anomalies and under confinement forms layers of\nparticles. The particle distributions of them, present different arrangements\nrelated to amorphous/solid phases. Here only the contact layer is analyzed\nthrough fractal singularity spectrum. At high densities the structural\ntransition its quantify by the order degree to determine the phases affected by\nthe confinement. This mapping shows that the system as the temperature\nincreased, the fractal dimension decreases, which is consistent with the\nbehavior studying in such systems. This result suggests that under\nthermodynamic perturbations, an anomalous confined liquid, presents different\nphase transitions achieving be characterized by its fractality.",
        "positive": "Chirality-Biased Point Defects Dynamics on a Disclination Line in a\n  Nematic Liquid Crystal: Chiral additives in the nematic liquid crystal can alter the dynamics of\npoint defects moving on a disclination line. They exert a constant force on\ndefects, leading to the bimodal distribution of distances between them at long\ntimes. The evolution of the system of defects in the presence of chiral\nadditives provides a very direct proof of the existence of repulsive forces\nbetween the defects at large distances. We find that addition of a sufficient\namount of chiral compound removes all point defects from the system. The\nprocess is studied in the system of 8CB (4-n-octyl-4 '-cyanobiphenyl) doped\nwith the chiral compound S811 (from Merck Co.) and in the computer simulations."
    },
    {
        "anchor": "Simulation and theory of fluid demixing and interfacial tension of\n  mixtures of colloids and non-ideal polymers: An extension of the Asakura-Oosawa-Vrij model of hard sphere colloids and\nnon-adsorbing polymers, that takes polymer non-ideality into account through a\nrepulsive stepfunction pair potential between polymers, is studied with grand\ncanonical Monte Carlo simulations and density functional theory. Simulation\nresults validate previous theoretical findings for the shift of the bulk fluid\ndemixing binodal upon increasing strength of polymer-polymer repulsion,\npromoting the tendency to mix. For increasing strength of the polymer-polymer\nrepulsion, simulation and theory consistently predict the interfacial tension\nof the free colloidal liquid-gas interface to decrease significantly for fixed\ncolloid density difference in the coexisting phases, and to increase for fixed\npolymer reservoir packing fraction.",
        "positive": "Dynamics of pulled desorption with effects of excluded volume\n  interaction: The p-Laplacian diffusion equation and its exact solution: We analyze the dynamics of desorption of a polymer molecule which is pulled\nat one of its ends with force $f$, trying to desorb it. We assume a monomer to\ndesorb when the pulling force on it exceeds a critical value $f_{c}$. We\nformulate an equation for the average position of the $n^{th}$ monomer, which\ntakes into account excluded volume interaction through the blob-picture of a\npolymer under external constraints. The approach leads to a diffusion equation\nwith a $p$-Laplacian for the propagation of the stretching along the chain.\nThis has to be solved subject to a moving boundary condition. Interestingly,\nwithin this approach, the problem can be solved exactly in the trumpet,\nstem-flower and stem regimes. In the trumpet regime, we get\n$\\tau=\\tau_{0}n_d^{2}$ where $n_d$ is the number of monomers that have desorbed\nat the time $\\tau$. $\\tau_{0}$ is known only numerically, but for $f$ close to\n$f_{c}$, it is found to be $\\tau_{0}\\sim f_c/(f^{2/3}-f_{c}^{2/3})$. If one\nused simple Rouse dynamics, this result changes to {\\normalsize $\\tau\\sim f_c\nn_d^2/(f-f_{c})$.} In the other regimes too, one can find exact solution, and\ninterestingly, in all regimes $\\tau \\sim n_d^2$."
    },
    {
        "anchor": "Light-controlled Assembly of Active Colloidal Molecules: Thanks to a constant energy input, active matter can self-assemble into\nphases with complex architectures and functionalities such as living clusters\nthat dynamically form, reshape and break-up, which are forbidden in equilibrium\nmaterials by the entropy maximization (or free energy minimization) principle.\nThe challenge to control this active self-assembly has evoked widespread\nefforts typically hinging on engineering of the properties of individual motile\nconstituents. Here, we provide a different route, where activity occurs as an\nemergent phenomenon only when individual building blocks bind together in a way\nthat we control by laser light. Using experiments and simulations of two\nspecies of immotile microspheres, we exemplify this route by creating active\nmolecules featuring a complex array of behaviors, becoming migrators, spinners\nand rotators. The possibility to control the dynamics of active self-assembly\nvia light-controllable nonreciprocal interactions will inspire new approaches\nto understand living matter and to design active materials.",
        "positive": "Thermalization of an impurity cloud in a Bose-Einstein condensate: We study the thermalization dynamics of an impurity cloud inside a\nBose-Einstein condensate at finite temperature, introducing a suitable\nBoltzmann equation. Some values of the temperature and of the initial impurity\nenergy are considered. We find that, below the Landau critical velocity, the\nmacroscopic population of the initial impurity state reduces its depletion\nrate. For sufficiently high velocities the opposite effect occurs. For\nappropriate parameters the collisions cool the condensate. The maximum cooling\nper impurity atom is obtained with multiple collisions."
    },
    {
        "anchor": "Motion by Stopping: Rectifying Brownian Motion of Non-spherical\n  Particles: We show that Brownian motion is spatially not symmetric for mesoscopic\nparticles embedded in a fluid if the particle is not in thermal equilibrium and\nits shape is not spherical. In view of applications on molecular motors in\nbiological cells, we sustain non-equilibrium by stopping a non-spherical\nparticle at periodic sites along a filament. Molecular dynamics simulations in\na Lennard-Jones fluid demonstrate that directed motion is possible without a\nratchet potential or temperature gradients if the asymmetric non-equilibrium\nrelaxation process is hindered by external stopping. Analytic calculations in\nthe ideal gas limit show that motion even against a fluid drift is possible and\nthat the direction of motion can be controlled by the shape of the particle,\nwhich is completely characterized by tensorial Minkowski functionals.",
        "positive": "Experiments on the twisted vortex state in superfluid 3He-B: We have performed measurements and numerical simulations on a bundle of\nvortex lines which is expanding along a rotating column of initially\nvortex-free 3He-B. Expanding vortices form a propagating front: Within the\nfront the superfluid is involved in rotation and behind the front the twisted\nvortex state forms, which eventually relaxes to the equilibrium vortex state.\nWe have measured the magnitude of the twist and its relaxation rate as function\nof temperature above 0.3Tc. We also demonstrate that the integrity of the\npropagating vortex front results from axial superfluid flow, induced by the\ntwist."
    },
    {
        "anchor": "Boundary flow of viscoelastic polyelectrolyte solutions: We report an investigation of the equilibrium and dynamic properties of\npolyelectrolyte solutions confined between platinum surfaces with a dynamic\nSurface Force Apparatus. The polyelectrolyte adsorbs on the surfaces in a dense\ncompact layer bearing a surface charge in good agreement with the theoretical\npredictions. The flow of the solution on this charged adsorbed layer is probed\nover four decades of spatial scales and one decade of frequency by dynamic\nmeasurements. At distances larger than the hundredth of nanometers, the flow of\nthe viscoelastic solution is well described by a partial slip boundary\ncondition. We show that the wall slip is quantitatively described by an\ninterfacial friction coefficient, according to the original Navier's\nformulation, and not by a slip length. At smaller distance the partial slip\nmodel overestimates the solution mobility, and we observe the presence of a low\nviscosity layer coating the surfaces. The viscosity and thickness of this\nboundary layer are directly resolved, and found to be independent on\nshear-rate, frequency, and confinement. We discuss the thickness of the low\nviscosity layer in terms of the structural length of the semi-dilute solution\nand the Debye length screening the adsorbed layer charge.",
        "positive": "Electroosmotic Flow in Different Phosphorus Nanochannels: The electrokinetic transport in a neutral system consists of an aqueous NaCl\nsolution confined in a nanochannel with two similar parallel phosphorene walls,\nand is investigated for different black, blue, red, and green phosphorene\nallotropes in the presence of an external electric field in the directions $x$\n(parallel to the walls roughness axis) and $y$ (perpendicular to the walls\nroughness axis). The results show that irrespective of the electric field\ndirection, the thickness of the Stern layer increases with the increase in the\nmagnitude of the negative electric surface charge density (ESCD) on the\nnanochannel walls, and it also increases with the increase in the roughness\nratio for different allotropes. Moreover, three different regimes of\nDebye--H\\\"{u}ckel (DH), intermediate, and flow reversal appear as the absolute\nvalue of the negative ESCD on the walls grows. With the increase in the\nabsolute value of the negative ESCD, in the DH regime, the flow velocity grows,\nthen in the intermediate regime, it decreases, and finally, at sufficiently\nhigh ESCD, the flow reversal occurs. When the external electric field is\napplied in the $y$ direction, the dynamics of the system are slower than that\nof the $x$ direction; therefore, the flow reversal occurs at the smaller\nabsolute values of the negative ESCD."
    },
    {
        "anchor": "Inertial migration of neutrally-buoyant particles in superhydrophobic\n  channels: At finite Reynolds numbers particles migrate across flow streamlines to their\nequilibrium positions in microchannels. Such a migration is attributed to an\ninertial lift force, and it is well-known that the equilibrium location of\nneutrally-buoyant particles is determined only by their size and the Reynolds\nnumber. Here we demonstrate that the decoration of a bottom wall of the channel\nby superhydrophobic grooves provides additional possibilities for manipulation\nof neutrally-buoyant particles. It is shown that the effective anisotropic\nhydrodynamic slip of such a bottom wall can be readily used to alter the\nequilibrium positions of particles and to generate their motion transverse to\nthe pressure gradient. These results may guide the design of novel inertial\nmicrofluidic devices for efficient sorting of neutrally-buoyant microparticles\nby their size.",
        "positive": "On the structure-viscoelasticity relationship of a dually crosslinked\n  reversible polymer network: We perform equilibrium Langevin dynamics simulations to understand the\nstructure-viscoelasticity relationship of a dually crosslinked reversible\npolymer network. The cross-linking is achieved by introducing orthogonal\ncrosslinkers (A and B) in to the polymer backbone, where only intra-species\nbonds (A-A or B-B) are allowed to be formed. We study the systems at infinite\ndilution and above the overlap concentration of the chains. We find the dually\ncross-linked chains to be more compact compared to the singly cross-linked\nchains at infinite dilution. At the finite concentration, we also explored the\nrole of weak (A-A) vs. strong (B-B) bonds in tuning the stress relaxation\nbehavior of the networks, by systematically varying the relative composition of\nA monomers (x) while keeping the total fraction of crosslinks as constant.\nInterestingly, we find a non-monotonic trend in the diffusivity and hence in\nthe stress auto-correlation function of the system w.r.t. x. Furthermore, we\nfind that in the dynamics in the plateau regime of the stress relaxation\nfunction is dictated by the strength of the weak bonds, whereas the terminal\nrelaxation behavior of the stress auto-correlation function depends on the\nstrength of the strong bonds. We also study the influence of the distribution\nof the A and B on the stress relaxation by carrying out additional simulations\nfor a symmetric distribution of the chains. Interestingly, we find the\ninter-molecular bonds to be significantly lower in the symmetric case which\nmakes it to have a faster stress relaxation compared to its random counterpart.\nOur study highlight the influence of the composition, distribution, and the\nbond energy disparity of the crosslinking monomers in tuning the\nviscoelasticity of the dual networks."
    },
    {
        "anchor": "Glass transitions and shear thickening suspension rheology: We introduce a class of simple models for shear thickening and/ or `jamming'\nin colloidal suspensions. These are based on schematic mode coupling theory\n(MCT) of the glass transition, having a memory term that depends on a density\nvariable, and on both the shear stress and the shear rate. (Tensorial aspects\nof the rheology, such as normal stresses, are ignored for simplicity.) We\ncalculate steady-state flow curves and correlation functions. Depending on\nmodel parameters, we find a range of rheological behaviours, including\n`S-shaped' flow curves, indicating discontinuous shear thickening, and\nstress-induced transitions from a fluid to a nonergodic (jammed) state, showing\nzero flow rate in an interval of applied stress. The shear thickening and\njamming scenarios that we explore appear broadly consistent with experiments on\ndense colloids close to the glass transition, despite the fact that we ignore\nhydrodynamic interactions. In particular, the jamming transition we propose is\nconceptually quite different from various hydrodynamic mechanisms of shear\nthickening in the literature, although the latter might remain pertinent at\nlower colloid densities. Our jammed state is a stress-induced glass, but its\nnonergodicity transitions have an analytical structure distinct from that of\nthe conventional MCT glass transition.",
        "positive": "Isotropic-nematic phase equilibria of polydisperse hard rods: The effect\n  of fat tails in the length distribution: We study the phase behaviour of hard rods with length polydispersity, treated\nwithin a simplified version of the Onsager model. We give a detailed\ndescription of the unusual phase behaviour of the system when the rod length\ndistribution has a \"fat\" (e.g. log-normal) tail up to some finite cutoff. The\nrelatively large number of long rods in the system strongly influences the\nphase behaviour: the isotropic cloud curve, which defines the where a nematic\nphase first occurs as density is increased, exhibits a kink; at this point the\nproperties of the coexisting nematic shadow phase change discontinuously. A\nnarrow three-phase isotropic-nematic-nematic coexistence region exists near the\nkink in the cloud curve, even though the length distribution is unimodal. A\ntheoretical derivation of the isotropic cloud curve and nematic shadow curve,\nin the limit of large cutoff, is also given. The two curves are shown to\ncollapse onto each other in the limit. The coexisting isotropic and nematic\nphases are essentially identical, the only difference being that the nematic\ncontains a larger number of the longest rods; the longer rods are also the only\nones that show any significant nematic ordering. Numerical results for finite\nbut large cutoff support the theoretical predictions for the asymptotic scaling\nof all quantities with the cutoff length."
    },
    {
        "anchor": "Making sessile drops easier: Using an identity, directly derived from the Young-Laplace equation, the\nproblem of the equilibrium shape of an axisymmetric sessile drop is reduced to\na one-parameter shooting method problem. Based on the method the numerical\nsolutions for drops with Bond number up to 15 are plotted. The agreement\nbetween the method and the ADSA-D method as well as the experimental data is\ntested. A Mathematica code based on the method is presented.",
        "positive": "Molecular dynamics simulation of the coalescence of surfactant-laden\n  droplets: We investigate the coalescence of surfactant-laden water droplets by using\nseveral different surfactant types and a wide range of concentrations by means\nof a coarse-grained model obtained by the statistical associating fluid theory.\nOur results demonstrate in detail a universal mass transport mechanism of\nsurfactant across many concentrations and several surfactant types during the\nprocess. Coalescence initiation is seen to occur via a single pinch due to\naggregation of surface surfactant, and its remnants tend to become engulfed in\npart inside the forming bridge. Across the board we confirm the existence of an\ninitial thermal regime with constant bridge width followed by a later inertial\nregime with bridge width scaling roughly as the square root of time, but see no\nevidence of an intermediate viscous regime. Coalescence becomes slower as\nsurfactant concentration grows, and we see evidence of the appearance of a\nfurther slowdown of a different nature for several times the critical\nconcentration. We anticipate that our results provide further insights in the\nmechanisms of coalescence of surfactant-laden droplets."
    },
    {
        "anchor": "Enhanced rotational motion of spherical squirmer in polymer solutions: The rotational diffusive motion of a self-propelled, attractive spherical\ncolloid immersed in a solution of self-avoiding polymers is studied by\nmesoscale hydrodynamic simulations. A drastic enhancement of the rotational\ndiffusion by more than an order of magnitude in the presence of activity is\nobtained. The amplification is a consequence of two effects, a decrease of the\namount of adsorbed polymers by active motion and an asymmetric encounter with\npolymers on the squirmer surface, which yields an additional torque and random\nnoise for the rotational motion. Our simulations suggest a way to control the\nrotational dynamics of squirmer-type microswimmers by the degree of polymer\nadsorption and system heterogeneity.",
        "positive": "Understanding self-assembled nanosphere patterns: Patterns generated by a colloidal suspension of nanospheres drying on a\nfrictional substrate are studied by experiments and computer simulations. The\nobtained two-dimensional self-assembled structures are commonly used for\nnanosphere lithography. A spring-block stick-slip model is introduced for\nsimulating the phenomenon and the influence of several controllable parameters\non the final structure is investigated. The model successfully reproduces the\nexperimentally observed patterns and the dynamics leading to pattern formation\nis revealed."
    },
    {
        "anchor": "Nanomechanical Measurements of Magnetostriction and Magnetic Anisotropy\n  in (Ga,Mn)As: A (Ga,Mn)As nanoelectromechanical resonator is used to obtain the first\ndirect measurement of magnetostriction in a dilute magnetic semiconductor.\nField-dependent magnetoelastic stress induces shifts in resonance frequency\nthat can be discerned with a high resolution electromechanical transduction\nscheme. By monitoring the field dependence, the magnetostriction and anisotropy\nfield constants can be simultaneously mapped over a wide range of temperatures.\nThese results, when compared with theoretical predictions, appear to provide\ninsight into a unique form of magnetoelastic behavior mediated by holes.",
        "positive": "Easier sieving through narrower pores: fluctuations and barrier crossing\n  in flow-driven polymer translocation: We show that the injection of polymer chains into nanochannels becomes easier\nas the channel becomes narrower. This counter intuitive result arises because\nof a decrease in the diffusive time scale of the chains with increasing\nconfinement. The results are obtained by extending the de Gennes blob model of\nconfined polymers, and confirmed by hybrid molecular dynamics -\nlattice-Boltzmann simulations."
    },
    {
        "anchor": "Absorbing Phase Transitions and Dynamic Freezing in Running Active\n  Matter Systems: We examine a two-dimensional system of sterically repulsive interacting disks\nwhere each particle runs in a random direction. This system is equivalent to a\nrun-and-tumble dynamics system in the limit where the run time is infinite. At\nlow densities, we find a strongly fluctuating state composed of transient\nclusters. Above a critical density that is well below the density at which\nnon-active particles would crystallize, the system can organize into a drifting\nquiescent or frozen state where the fluctuations are lost and large\ncrystallites form surrounded by a small density of individual particles.\nAlthough all the particles are still moving, their paths form closed orbits.\nThe average transient time to organize into the quiescent state diverges as a\npower law upon approaching the critical density from above. We compare our\nresults to the random organization observed for periodically sheared systems\nthat can undergo an absorbing transition from a fluctuating state to a\ndynamical non-fluctuating state. In the random organization studies, the system\norganizes to a state in which the particles no longer interact; in contrast, we\nfind that the randomly running active matter organizes to a strongly\ninteracting dynamically jammed state. We show that the transition to the frozen\nstate is robust against a certain range of stochastic fluctuations. We also\nexamine the effects of adding a small number of pinned particles to the system\nand find that the transition to the frozen state shifts to significantly lower\ndensities and arises via the nucleation of faceted crystals centered at the\nobstacles.",
        "positive": "Understanding the problem of glass transition on the basis of elastic\n  interactions in a liquid: We review the recently proposed elastic approach to glass transition. This\napproach is based on a simple and a physically transparent idea of elastic\ninteractions between local relaxation events in a liquid. Central to this\npicture is the range of this interaction. Its increase on lowering the\ntemperature explains several important open questions in the area of glass\ntransition, including universal relaxation laws and dynamic crossovers. In\nparticular, we show how the proposed theory explains (1) the physical origin of\ncooperativity of relaxation; (2) the origin of the crossover from exponential\nto non-exponential relaxation at $\\tau=$1 ps, where $\\tau$ is liquid relaxation\ntime; (3) the origin of the Vogel-Fulcher-Tammann law; (4) the origin of\nstretched-exponential relaxation; (5) the absence of divergence of $\\tau$ at\nthe VFT temperature $T_0$ and the crossover to a more Arrhenius relaxation at\n$\\tau\\approx 10^{-6}$ sec; (6) the origin of liquid ``fragility''; and (7) the\nrelationship between non-exponentiality of relaxation and relaxation time."
    },
    {
        "anchor": "Diffusive dynamics of contact formation in disordered polypeptides: Experiments measuring contact formation between a probe and quencher in\ndisordered chains provide information on the fundamental dynamical timescales\nrelevant to protein folding, but their interpretation usually relies on\nsimplified one-dimensional (1D) diffusion models. Here, we use all-atom\nmolecular simulations to capture both the time-scales of contact formation, as\nwell as the scaling with the length of the peptide for tryptophan triplet\nquenching experiments. Capturing the experimental quenching times depends on\nthe water viscosity, but more importantly on the configurational space explored\nby the chain. We also show that very similar results are obtained from\nSzabo-Schulten-Schulten theory applied to a 1D diffusion model derived from the\nsimulations, supporting the validity of such models. However, we also find a\nsignificant reduction in diffusivity at small separations, those which are most\nimportant in determining the quenching rate.",
        "positive": "Self-propelled particle in a nonconvex external potential: Persistent\n  limit in one dimension: Equilibrium mapping techniques for nonaligning self-propelled particles have\nmade it possible to predict the density profile of an active ideal gas in a\nwide variety of external potentials, however they fail when the self-propulsion\nis very persistent and the potential is nonconvex, which is precisely when the\nmost uniquely active phenomena occur. Here we show how to predict the density\nprofile of a 1D active Ornstein-Uhlenbeck particle in an arbitrary external\npotential in the persistent limit and discuss the consequences of the\npotential's nonconvexity on the structure of the solution, including the\ncentral role of the potential's inflection points and the nonlocal dependence\nof the density profile on the potential."
    },
    {
        "anchor": "Electrostatic energy barriers from dielectric membranes upon approach of\n  translocating DNA molecules: We probe the electrostatic cost associated with the approach phase of DNA\ntranslocation events. Within an analytical theory at the Debye-Huckel level, we\ncalculate the electrostatic free energy of a rigid DNA molecule interacting\nwith a dielectric membrane. For carbon or silicon based low permittivity\nneutral membranes, the DNA molecule experiences a repulsive energy barrier\nbetween 10 kBT and 100 kBT. In the case of engineered membranes with high\ndielectric permittivity, the membrane surface attracts the DNA with an energy\nof the same magnitude. Both the repulsive and attractive interactions result\nfrom image-charge effects and their magnitude survive even for the thinnest\ngraphene-based membranes of size d~6 A. For weakly charged membranes, the\nelectrostatic free energy is always attractive at large separation distances\nbut switches to repulsive close to the membrane surface. We also characterise\nthe polymer length dependence of the interaction energy. For specific values of\nthe membrane charge density, low permittivity membranes repel short polymers\nbut attract long polymers. Our results can be used to control the strong\nelectrostatic free energy of DNA-membrane interactions prior to translocation\nevents by chemical engineering of the relevant system parameters.",
        "positive": "Tensorial conservation law for nematic polymers: We derive the \"conservation law\" for nematic polymers in tensorial form valid\nfor quadrupolar orientational order in contradistinction to the conservation\nlaw in the case of polar orientational order. Due to microscopic differences in\nthe coupling between the orientational field deformations and the density\nvariations for polar and quadrupolar order, we find that respective order\nparameters satisfy fundamentally distinct constraints. Being necessarily scalar\nin its form, the tensorial conservation law is obtained straightforwardly from\nthe gradients of the polymer nematic tensor field and connects the spatial\nvariation of this tensor field with density variations. We analyze the\ndifferences between the polar and the tensorial forms of the conservation law,\npresent some explicit orientational fields that satisfy this new constraint and\ndiscuss the role of singular \"hairpins\", which do not affect local quadrupolar\norder of polymer nematics, but nevertheless influence its gradients."
    },
    {
        "anchor": "Effect of an electric field on a floating lipid bilayer: a neutron\n  reflectivity study: We present here a neutron reflectivity study of the influence of an\nalternative electric field on a supported phospholipid double bilayer. We\nreport for the first time a reproducible increase of the fluctuation amplitude\nleading to the complete unbinding of the floating bilayer. Results are in good\nagreement with a semi-quantitative interpretation in terms of negative\nelectrostatic surface tension.",
        "positive": "Stability of Texture and Shape of Circular Domains of Langmuir\n  Monolayers: Finite domains of a Langmuir monolayer in a phase with tilted molecules can\nbe modeled by a simple elastic free energy of an XY order parameter with\nisotropic and anisotropic line tension terms. The domains can and often do\ncontain nontrivial textures, which in turn influence the shape of the domains.\nHerein we investigate the properties of a simplified isotropic model with a\nsingle elastic constant. For circular domains a first-order phase transition is\nfound between two distinct textures: an exterior defect (or ``virtual boojum'')\ntexture, and an interior defect texture. Starting with a circular domain and\neither of these two textures as a ground state, we find shape instabilities\ndevelop that depend on the elastic constants and line tensions in the\nsimplified model. In both cases a necessary but not sufficient condition for\nthe onset of shape instabilities is the possibility for a local negative\neffective line tension to develop from the anisotropic line tension term."
    },
    {
        "anchor": "Simulation of Heme using DFT+U: a step toward accurate spin-state\n  energetics: We investigate the DFT+U approach as a viable solution to describe the\nlow-lying states of ligated and unligated iron heme complexes. Besides their\ncentral role in organometallic chemistry, these compounds represent a\nparadigmatic case where LDA, GGA, and common hybrid functionals fail to\nreproduce the experimental magnetic splittings. In particular, the imidazole\npentacoordinated heme is incorrectly described as a triplet by all usual DFT\nflavors. In this study we show that a U parameter close to 4 eV leads to spin\ntransitions and molecular geometries in quantitative agreement with\nexperiments, and that DFT+U represents an appealing tool in the description of\niron porphyrin complexes, at a much reduced cost compared to correlated\nquantum-chemistry methods. The possibility of obtaining the U parameter from\nfirst-principles is explored through a self-consistent linear-response\nformulation. We find that this approach, which proved to be successful in other\niron systems, produces in this case some overestimation with respect to the\noptimal values of U.",
        "positive": "Power law viscoelasticity of a fractal colloidal gel: Power law rheology is of widespread occurrence in complex materials that are\ncharacterized by the presence of a very broad range of microstructural length\nand time scales. Although phenomenological models able to reproduce the\nobserved rheological features exist, in general a well-established connection\nwith the microscopic origin of this mechanical behavior is still missing. As a\nmodel system, this work focuses on a fractal colloidal gel. We thoroughly\ncharacterize the linear power law rheology of the sample and its age\ndependence. We show that at all sample ages and for a variety of rheological\ntests the gel linear viscoelasticity is very accurately described by a\nFractional Maxwell (FM) model, characterized by a power law behavior. Thanks to\na unique set-up that couples small-angle static and dynamic light scattering to\nrheological measurements, we demonstrate that the power law rheology observed\nin the linear regime originates from reversible non-affine rearrangements and\ndiscuss the possible relationship between the FM model and the microscopic\nstructure of the gel."
    },
    {
        "anchor": "Radial hopper flow prediction using a constitutive model with\n  microstructure evolution: We present theoretical predictions of granular flow in a conical hopper based\non a continuum theory employing a recently-developed constitutive model with\nmicrostructure evolution by Sun and Sundaresan [1]. The model is developed for\nstrain rate-independent granular flows. The closures for the pressure and the\nmacroscopic friction coefficient are linked to microstructure through evolution\nequations for the coordination number and fabric. The material constants in the\nmodel are functions of particle-level properties. A salient prediction is the\nvariable stress ratio along the flow direction, in contrast to the constant\nratio employed in some widely-used plasticity theories, but supported by\nresults obtained from discrete element simulations. The model permits direct\ninterrogation of the influence of particle-particle friction as well as\nnormal-stress differences on the stress distribution and discharge rate.\nIncreasing particle friction leads to higher stress ratios, but lower normal\nstress and flow rates, while considering normal-stress differences results in\nthe opposite effects.",
        "positive": "Physical limits to biomechanical sensing: Cells actively probe and respond to the stiffness of their surroundings.\nSince mechanosensory cells in connective tissue are surrounded by a disordered\nnetwork of biopolymers, their in vivo mechanical environment can be extremely\nheterogeneous. Here, we investigate how this heterogeneity impacts\nmechanosensing by modeling the cell as an idealized local stiffness sensor\ninside a disordered fiber network. For all types of networks we study,\nincluding experimentally-imaged collagen and fibrin architectures, we find that\nmeasurements applied at different points throughout a given network yield a\nstrikingly broad range of local stiffnesses, spanning roughly two decades. We\nverify via simulations and scaling arguments that this broad range of local\nstiffnesses is a generic property of disordered fiber networks, and show that\nthe range can be further increased by tuning specific network features,\nincluding the presence of long fibers and the proximity to elastic transitions.\nThese features additionally allow for a highly tunable dependence of stiffness\non probe length. Finally, we show that to obtain optimal, reliable estimates of\nglobal tissue stiffness, a cell must adjust its size, shape, and position to\nintegrate multiple stiffness measurements over extended regions of space."
    },
    {
        "anchor": "Microstructures and Mechanical Properties of Dense Particle Gels:\n  Microstructural Characterization: The macroscopic mechanical properties of densely packed coagulated colloidal\nparticle gels strongly depend on the local arrangement of the powder particles\non length scales of a few particle diameters. Heterogeneous microstructures\nexhibit up to one order of magnitude higher elastic properties and yield\nstrengths than their homogeneous counterparts. The microstructures of these\ngels are analyzed by the straight path method quantifying quasi-linear particle\narrangements of particles. They show similar characteristics than force chains\nbearing the mechanical load in granular material. Applying this concept to gels\nrevealed that heterogeneous colloidal microstructures show a significantly\nhigher straight paths density and exhibit longer straight paths than their\nhomogeneous counterparts.",
        "positive": "Logarithmic Relaxation in a Kinetically Constrained Model: We present Monte Carlo simulations in a modification of the\nnorth-or-east-or-front model recently investigated by Berthier and Garrahan [J.\nPhys. Chem. B 109, 3578 (2005)]. In this coarse-grained model for relaxation in\nsupercooled liquids, the liquid structure is substituted by a three-dimensional\narray of cells. A spin variable is assigned to each cell, with values 0 or 1\ndenoting respectively unexcited and excited local states in a mobility field.\nChange in local mobility (spin flip) for a given cell is permitted according to\nkinetic constraints determined by the mobilities of neighboring cells. In this\nwork we keep the same kinetic constraints of the original model, but we\nintroduce two types of cells (denoted as \"fast'' and \"slow'') with very\ndifferent rates for spin flip. As a consequence, fast and slow cells exhibit\nvery different relaxation times for spin correlators. While slow cells exhibit\nstandard relaxation, fast cells display anomalous relaxation, characterized by\na concave-to-convex crossover in spin correlators by changing temperature or\ncomposition. At intermediate state points logarithmic relaxation is observed\nover three time decades. These results display striking analogies with dynamic\ncorrelators reported in recent simulations on a bead-spring model for polymer\nblends."
    },
    {
        "anchor": "Hard ellipses: Equation of state, structure and self-diffusion: We present an event-driven molecular dynamics study for hard ellipses and\nassess the effects of aspect ratio and area fraction on their physical\nproperties. For state points in the plane of aspect ratio (k=1-9) and area\nfraction (phi=0.01-0.8), we identify three different phases, including\nisotropic, plastic and nematic states. The equation of state (EOS) is shown for\na wide range of aspect ratios and is compared with the scaled particle theory\n(SPT) for the isotropic states. We find that SPT provides a good description of\nthe EOS for the isotropic phase of hard ellipses. At large fixed phi, the\nreduced pressure p increases with k in both the isotropic and the plastic\nphases, and interestingly, its dependence on k is rather weak in the nematic\nphase. We rationalize the thermodynamics of hard ellipses in terms of particle\nmotions. The plastic crystal is shown to form for aspect ratios up to k=1.4,\nwhile appearance of the stable nematic phase starts approximately at k=3. We\nquantitatively determine the locations of the isotropic-plastic (I-P)\ntransition and the isotropic-nematic (I-N) transition by analyzing the\nbond-orientation correlations and the angular correlations, respectively. As\nexpected, the I-P transition point is found to increase with k, while a larger\nk leads to a smaller area fraction where the I-N transition takes place.\nMoreover, our simulations strongly support that the two-dimensional nematic\nphase in hard ellipses has only quasi-long-range orientational order. The\nself-diffusion of hard ellipses is further explored and connections are\nrevealed between the structure and the self-diffusion. We discuss the relevance\nof our results to the glass transition in hard ellipses. Finally, the results\nof the isodiffusivity lines are evaluated for hard ellipses and we discuss the\neffect of spatial dimension on the diffusive dynamics of hard ellipsoidal\nparticles.",
        "positive": "Reply to Comment on`Entropy production and fluctuation theorems for\n  active matter': This is a reply to the comment to a letter by D. Mandal, K. Klymko and M. R.\nDeWeese published as Phys. Rev. Lett. 119, 258001 (2017)."
    },
    {
        "anchor": "A simple thermodynamic framework for heat-conducting flows of mixtures\n  of two interacting fluids: Within the theory of interacting continua, we develop a model for a heat\nconducting mixture of two interacting fluids described in terms of the\ndensities and the velocities for each fluid and the temperature field for the\nmixture as a whole. We use a general thermodynamic framework that determines\nthe response of the material from the knowledge of two pieces of information,\nnamely how the material stores the energy and how the entropy is produced. This\ninformation is expressed in the form of the constitutive equations for two\nscalars: the Helmholtz free energy and the entropy production. Additionally, we\nfollow the goal to determine the response of a mixture from a small (minimal)\nset of material parameters, including shear viscosity, bulk viscosity and heat\nconductivity associated with the mixture as a whole and the drag coefficient\nconnected with the interaction force between the constituents. The same\nthermodynamic approach is used to obtain the model when the mixture as a whole\nresponses as an incompressible material. For both the compressible and\nincompressible mixtures, we investigate three variants stemming from different\ndefinitions of the (averaged) velocity associated with the mixture as a whole.\nWe also address the issue of identification of boundary conditions for the\nindividual constituents from the standard boundary conditions formulated in\nterms of the quantities associated with the mixture as a whole.",
        "positive": "Splay-induced order in systems of hard wedges: We studied equilibrium systems composed of wedge-shaped monodisperse\nmolecules using hard-particle Monte Carlo simulations. Each model molecule was\nmade up of six colinear tangent spheres with linearly decreasing diameters.\nThus, the shape was unequivocally described by a single parameter $d$: the\nratio of the smallest and largest diameters of the spheres. The phases of the\nsystems were analyzed as a function of $d$ and packing density $\\eta$. As\ninteractions were purely of the excluded volume type, the emergent phases were\ngoverned solely by the configurational entropy. For $\\eta < 0.5$, in addition\nto the isotropic liquid, we observed standard nematic and smectic A liquid\ncrystalline phases. However, for $\\eta > 0.5$, apart from the ordinary\nnon-polar hexagonal crystal, three new frustrated polar crystalline phases with\nsplay modulation appeared: antiferroelectric splay crystal\n($\\text{Cr}_\\text{S}\\text{P}_\\text{A}$), antiferroelectric double splay crystal\n($\\text{Cr}_\\text{DS}\\text{P}_\\text{A}$) and ferroelectric double splay crystal\n($\\text{Cr}_\\text{DS}\\text{P}_\\text{F}$). All configurations were studied in\nterms of nematic, smectic, and hexatic order parameters, as well as the radial\ndistribution function and the polarization correlation function."
    },
    {
        "anchor": "Spin waves in a Bose Ferromagnet: It is shown that the ferromagnetic transition takes place always above\nBose-Einstein condensation in ferromagnetically coupled spinor Bose gases. We\ndescribe the Bose ferromagnet within Ginzburg-Landau theory by a \"two-fluid\"\nmodel below Bose-Einstein condensation. Both the Bose condensate and the normal\nphase are spontaneously magnetized. As a main result we show that spin waves in\nthe two fluids are coupled together so as to produce only one mixed spin-wave\nmode in the coexisting state. The long wavelength spectrum is quadratic in the\nwave vector ${\\bf k}$, consistent with usual ferromagnetism theory, and the\nspin-wave stiffness coefficient $c_s$ includes contributions from both the two\nphases, implying the \"two-fluid\" feature of the system. $c_s$ can show a sharp\nbend at the Bose-Einstein condensation temperature.",
        "positive": "Bulk and Surface Properties of Dipolar Fluids: Based on density-functional theory we analyze the full phase diagram, the\noccurrence of long-ranged orientational order, and the structural properties of\ndipolar fluids. As a model system we consider the Stockmayer fluid that\nconsists of spherical particles interacting via a Lennard-Jones potential plus\ndipolar forces. For sufficiently strong dipole moments one finds a region where\na fluid phase with long-ranged orientational order is stable. For all sample\nshapes with the exception of a long thin needle this phase exhibits a spatially\ninhomogeneous magnetization which depends on the actual shape. We determine the\ndetails of the magnetization structure in a cubic sample in the absence and in\nthe presence of an external magnetic field. One obtains a vortexlike structure\nwith an escape of the magnetization into the axis direction near the vortex\naxis and two point defects where the absolute value of the magnetization is\nstrongly reduced. If the spherical cores of the particles are replaced by\nelongated or oblate shapes a nematic phase without spontaneous magnetization is\nalso possible due to the anisotropic steric interactions. We study the\ninterplay of this nematic ordering with ferromagnetism in fluids of dipolar\nhard ellipsoids. Orientational order arises locally in the isotropic fluid\nphases near the liquid-gas interface of the Stockmayer fluid.\nDensity-functional theory allows us to determine density and orientational\norder profiles as well as the surface tension of this interface."
    },
    {
        "anchor": "Evolution of particle-scale dynamics in an aging clay suspension: Multispeckle x-ray photon correlation spectroscopy was employed to\ncharacterize the slow dynamics of a colloidal suspension formed by\nhighly-charged, nanometer-sized disks. At scattering wave vectors $q$\ncorresponding to interparticle length scales, the dynamic structure factor\nfollows a form $f(q,t) \\sim \\exp[-(t/\\tau)^{\\beta}$], where $\\beta \\approx$\n1.5. The characteristic relaxation time $\\tau$ increases with the sample age\n$t_a$ approximately as $\\tau \\sim t_a^{1.8}$ and decreases with $q$\napproximately as $\\tau \\sim q^{-1}$. Such a compressed exponential decay with\nrelaxation time that varies inversely with $q$ is consistent with recent models\nthat describe the dynamics in disordered elastic media in terms of strain from\nrandom, local structural rearrangements. The amplitude of the measured decay in\n$f(q,t)$ varies with $q$ in a manner that implies caged particle motion at\nshort times. The decrease in the range of this motion and an increase in\nsuspension conductivity with increasing $t_a$ indicate a growth in the\ninterparticle repulsion as the mechanism for internal stress development\nimplied by the models.",
        "positive": "Dielectric spectroscopy of a ferroelectric nematic liquid crystal and\n  the effect of the sample thickness: The recently discovered ferroelectric nematic liquid crystals have been\nreported to exhibit very large dielectric permittivity values. Here, we report\na systematic investigation of the dielectric behavior of a prototypical\nferroelectric nematogen by varying the thickness of the parallel capacitor\nmeasuring cell. While in the non-polar high temperature nematic phase results\nshow only slight differences due to slight variations of the alignment, the\nmeasured permittivity values in the ferroelectric nematic phase show a linear\ndependence on the cell thickness. It is also shown that the characteristic\nrelaxation frequency decreases inversely proportionally to the thickness. The\nresults are discussed in terms of three different available models based on\ndifferent underlying mechanisms, accounting for cancellation of the probe\nelectric fields by polarization reorientation or by ionic charges, or based on\na recently proposed continuous phenomenological model."
    },
    {
        "anchor": "Characteristic Angles in the Wetting of an Angular Region: Deposit\n  Growth: As was shown in an earlier paper [1], solids dispersed in a drying drop\nmigrate to the (pinned) contact line. This migration is caused by outward flows\ndriven by the loss of the solvent due to evaporation and by geometrical\nconstraint that the drop maintains an equilibrium surface shape with a fixed\nboundary. Here, in continuation of our earlier paper [2], we theoretically\ninvestigate the evaporation rate, the flow field and the rate of growth of the\ndeposit patterns in a drop over an angular sector on a plane substrate.\nAsymptotic power laws near the vertex (as distance to the vertex goes to zero)\nare obtained. A hydrodynamic model of fluid flow near the singularity of the\nvertex is developed and the velocity field is obtained. The rate of the deposit\ngrowth near the contact line is found in two time regimes. The deposited mass\nfalls off as a weak power Gamma of distance close to the vertex and as a\nstronger power Beta of distance further from the vertex. The power Gamma\ndepends only slightly on the opening angle Alpha and stays between roughly -1/3\nand 0. The power Beta varies from -1 to 0 as the opening angle increases from 0\nto 180 degrees. At a given distance from the vertex, the deposited mass grows\nfaster and faster with time, with the greatest increase in the growth rate\noccurring at the early stages of the drying process.",
        "positive": "Colloidal Gels: Equilibrium and Non-Equilibrium Routes: We attempt a classification of different colloidal gels based on\ncolloid-colloid interactions. We discriminate primarily between non-equilibrium\nand equilibrium routes to gelation, the former case being slaved to\nthermodynamic phase separation while the latter is individuated in the\nframework of competing interactions and of patchy colloids. Emphasis is put on\nrecent numerical simulations of colloidal gelation and their connection to\nexperiments. Finally we underline typical signatures of different gel types, to\nbe looked in more details in experiments."
    },
    {
        "anchor": "Inducing Stratification of Colloidal Mixtures with a Mixed Binary\n  Solvent: Molecular dynamics simulations are used to demonstrate that a binary solvent\ncan be used to stratify colloidal mixtures when the suspension is rapidly\ndried. The solvent consists of two components, one more volatile than the\nother. When evaporated at high rates, the more volatile component becomes\ndepleted near the evaporation front and develops a negative concentration\ngradient from the bulk of the mixture to the liquid-vapor interface while the\nless volatile solvent is enriched in the same region and exhibit a positive\nconcentration gradient. Such gradients can be used to drive a binary mixture of\ncolloidal particles to stratify if one is preferentially attracted to the more\nvolatile solvent and the other to the less volatile solvent. During solvent\nevaporation, the fraction of colloidal particles preferentially attracted to\nthe less volatile solvent is enhanced at the evaporation front, whereas the\ncolloidal particles having stronger attractions with the more volatile solvent\nare driven away from the interfacial region. As a result, the colloidal\nparticles show a stratified distribution after drying, even if the two colloids\nhave the same size.",
        "positive": "How does the preparation strategy influence the gold cap of\n  thermophoretic Janus swimmers and their propulsion?: The motion of partly gold (Au)-coated Janus particles under laser irradiation\nis caused by self-thermophoresis. Despite numerous studies addressing this\ntopic, the impact of the preparation method and the degree of coverage of the\nparticle with Au on the resulting thermophoretic velocity has not yet been\nfully understood. A detailed understanding of the most important tuning\nparameters during the preparation process is crucial to design Janus particles\nthat are optimized in Au coverage to receive a high thermophoretic velocity. In\nthis study, we explore the influence of the fabrication process, which changes\nthe Au cap size, on the resulting self-propulsion behavior of partly Au-coated\npolystyrene particles (Au-PS). Additionally, also the impact of an underlying\nadhesion chromium layer is investigated. In addition to the most commonly used\nqualitative SEM and EDX measurements, we propose a novel technique utilizing\nAFM studies to quantify the cap size. This non-invasive technique can be used\nto determine both the size and the maximum thickness of the Au cap. The Au cap\nsize was systematically varied in a range between about 36 % and 74 % by\ndifferent preparation strategies. Nevertheless, we showed that the differing Au\ncap size of the Janus particles in this range has no effect on the\nthermophoretic velocity. This surprising result is discussed in the paper."
    },
    {
        "anchor": "Structure of high-pressure supercooled and glassy water: We numerically investigate the metastable equilibrium structure of deep\nsupercooled and glassy water under pressure, covering the range of densities\ncorresponding to the experimentally produced high-density and very-high-density\namorphous phases. At $T = 188$ K, a continuous increase in density is observed\non varying pressure from $2.5$ to $13$ kbar, with no signs of first-order\ntransitions. Exploiting a recently proposed approach to the analysis of the\nradial distribution function -- based on topological properties of the\nhydrogen-bond network -- we are able to identify well-defined local geometries\nthat involve pair of molecules separated by multiple hydrogen bonds, specific\nof the high and very high density structures.",
        "positive": "Topological and Geometrical Random Walks on Bidisperse Random Sphere\n  Packings: Motivated by a problem arising from pharmaceutical science [B. Baeumer et\nal., Discr. Contin. Dyn. Sys. B 12], we study random walks on the contact graph\nof a bidisperse random sphere packing. For a random walk on the unweighted\ngraph that terminates in a specified target set, we compare the number of steps\nand the total euclidean length of the walk. We find a linear relationship\nbetween the two metrics with a proportionality constant that can be calculated\nfrom the edge length probabilities of the contact graph."
    },
    {
        "anchor": "Reversibility of granular rotations and translations: We analyze reversibility of both displacements and rotations of spherical\ngrains in three-dimensional compression experiments. Using transparent acrylic\nbeads with cylindrical holes and index matching techniques, we are not only\ncapable of tracking displacements but also, for the first time, analyze\nreversibility of rotations. We observe that for moderate compression\namplitudes, up to one bead diameter, the translational displacements of the\nbeads after each cycle become mostly reversible after an initial transient. By\ncontrast, granular rotations are largely irreversible. We find a weak\ncorrelation between translational and rotational displacements, indicating that\nrotational reversibility depends on more subtle changes in contact\ndistributions and contact forces between grains compared with displacement\nreversibility.",
        "positive": "Biaxiality at the Isotropic-Nematic Interface with Planar Anchoring: We revisit the classic problem of the structure of the isotropic-nematic\ninterface within Ginzburg-Landau-de Gennes theory, refining previous analytic\ntreatments of biaxiality at the interface. We compare our analysis with\nnumerical results obtained through a highly accurate spectral collocation\nscheme for the solution of the Landau-Ginzburg-de Gennes equations. In\ncomparison to earlier work, we obtain improved agreement with numerics for both\nthe uniaxial and biaxial profiles, accurate asymptotic results for the decay of\nbiaxial order on both nematic and isotropic sides of the interface and accurate\nfits to data from density functional approaches to this problem."
    },
    {
        "anchor": "Wetting gradient induced separation of emulsions: A combined\n  experimental and lattice Boltzmann computer simulation study: Guided motion of emulsions is studied via combined experimental and\ntheoretical investigations. The focus of the work is on basic issues related to\ndriving forces generated via a step-wise (abrupt) change in wetting properties\nof the substrate along a given spatial direction. Experiments on binary\nemulsions unambiguously show that selective wettability of the one of the fluid\ncomponents (water in our experiments) with respect to the two different parts\nof the substrate is sufficient in order to drive the separation process. These\nstudies are accompanied by approximate analytic arguments as well as lattice\nBoltzmann computer simulations, focusing on effects of a wetting gradient on\ninternal droplet dynamics as well as its relative strength compared to\nvolumetric forces driving the fluid flow. These theoretical investigations show\nqualitatively different dependence of wetting gradient induced forces on\ncontact angle and liquid volume in the case of an open substrate as opposed to\na planar channel. In particular, for the parameter range of our experiments,\nslit geometry is found to give rise to considerably higher separation forces as\ncompared to open substrate.",
        "positive": "Maier-Saupe nematogenic fluid: field theoretical approach: We adopt a field theoretical approach to study the structure and\nthermodynamics of a homogeneous Maier-Saupe nematogenic fluid interacting with\nanisotropic Yukawa potential. In the mean field approximation we retrieve the\nstandard Maier-Saupe theory for liquid crystals. In this theory the density is\nexpressed via the second order Legendre polynomial of molecule orientations. In\nthe Gaussian approximation we obtain analytical expressions for the correlation\nfunctions, the elasticity constant, the free energy, the pressure, and the\nchemical potential. We also use Ward symmetry identities to set a simple\ncondition for the correlation functions. Subsequently we find corrections due\nto fluctuations and show that density now contains Legendre polynomials of\nhigher orders."
    },
    {
        "anchor": "Tension-Induced Morphological Transition in Mixed Lipid Bilayers: Recently, Rozovsky et al. reported on the morphology and dynamics of\nsuperstructures in three-component lipid bilayers containing saturated and\nunsaturated lipids as well as cholesterol [J. Am. Chem. Soc. 127, 36 (2005)].\nWe comment that the observed sequence of the stripe to hexagonal morphological\ntransition in mixed bilayers can be attributed to an enhanced membrane surface\ntension that is induced by the vesicle adhesion on the solid surface.",
        "positive": "Quasi-gaussian velocity distribution of a vibrated granular bilayer\n  system: We show by using a Discrete Element Method that a bilayer of vibrated\ngranular bidisperse spheres exhibits the striking feature that the horizontal\nvelocity distribution of the top layer particles has a quasi-Gaussian shape,\nwhereas that of the bottom layer is far from Gaussian. We examine in detail the\nrelevance of all physical parameters (acceleration of the bottom plate, mass\nratio, layer coverage). Moreover, a microscopic analysis of the trajectories\nand the collision statistics reveal how the mechanism of randomization."
    },
    {
        "anchor": "Soft particles at liquid interfaces: From molecular particle\n  architecture to collective phase behavior: Soft particles such as microgels and core-shell particles can undergo\nsignificant and anisotropic deformations when adsorbed to a liquid interface.\nThis, in turn, leads to a complex phase behavior upon compression. Here we\ndevelop a multiscale framework to rationally link the molecular particle\narchitecture to the resulting interfacial morphology and, ultimately, to the\ncollective interfacial phase behavior, enabling us to identify the key\nsingle-particle properties underlying two-dimensional continuous,\nheterostructural, and isostructural solid-solid transitions. Our approach\nresolves existing discrepancies between experiments and simulations and thus\nprovides a unifying framework to describe phase transitions in interfacial\nsoft-particle systems. We establish proof-of-principle for our rational\napproach by synthesizing three different poly(N-isopropylacrylamide)\nsoft-particle architectures, each of which corresponds to a different targeted\nphase behavior. In parallel, we introduce a versatile and highly efficient\ncoarse-grained simulation method that adequately captures the qualitative key\nfeatures of each soft-particle system; the novel ingredient in our simulation\nmodel is the use of auxiliary degrees of freedom to explicitly account for the\nswelling and collapse of the particles as a function of surface pressure.\nNotably, these combined efforts allow us to establish the first experimental\ndemonstration of a heterostructural transition to a chain phase in a\nsingle-component system, as well as the first accurate in silico account of the\ntwo-dimensional isostructural transition. Overall, our multiscale framework\nprovides a bridge between physicochemical soft-particle characteristics at the\nmolecular- and nanoscale and the collective self-assembly phenomenology at the\nmacroscale, paving the way towards novel materials with on-demand interfacial\nbehavior.",
        "positive": "Microscopic theory for the phase separation of self-propelled repulsive\n  disks: Motivated by recent experiments on colloidal suspensions, we study\nanalytically and numerically a microscopic model for self-propelled particles\nlacking alignment interactions. In this model, even for purely repulsive\ninteractions, a dynamical instability leading to phase separation has been\nreported. Starting from the many-body Smoluchowski equation, we develop a\nmean-field description based on a novel closure scheme and derive the effective\nhydrodynamic equations. We demonstrate that the microscopic origin of the\ninstability is a force imbalance due to an anisotropic pair distribution\nleading to self-trapping. The phase diagram can be understood in terms of two\nquantities: a minimal drive and the force imbalance. At sufficiently high\npropulsion speeds there is a reentrance into the disordered fluid."
    },
    {
        "anchor": "Defect-Defect Interactions in the Buckling of Imperfect Spherical Shells: We perform finite element simulations to study the impact of defect-defect\ninteractions on the pressure-induced buckling of thin, elastic, spherical\nshells containing two dimpled imperfections. Throughout, we quantify the\ncritical buckling pressure of these shells using their knockdown factor. We\nexamine cases featuring either identical or different geometric defects and\nsystematically explore the parameter space, including the angular separation\nbetween the defects, their widths and amplitudes, and the radius-to-thickness\nratio of the shell. As the angular separation between the defects is increased,\nthe buckling strength initially decreases, then increases before reaching a\nplateau. Our primary finding is that the onset of defect-defect interactions,\nas quantified by a characteristic length scale associated with the onset of the\nplateau, is set by the critical buckling wavelength reported in the classic\nshell-buckling literature. Beyond this threshold, within the plateau regime,\nthe buckling behavior of the shell is dictated by the largest defect.",
        "positive": "A multiphase constitutive modeling framework for unsaturated soil\n  behavior: We develop a framework for constitutive modeling of unsaturated soils that\nhas the embedded elements of lower scale grain to grain contacts. Continuum\nmodels developed from this framework will possess two different phases\nidealizing the solid grains and their interactions. As a consequence, two\ndifferent constitutive relationships, corresponding to the grain to grain\ncontact and bulk behavior, co-exist in a constitutive model and govern the\nresponse of the model. To be specific, grain to grain sliding under dry or wet\ncondition is idealized and appears as a simple contact law embedded in a\ncontinuum framework. There is no need to define plastic strain, as this\nquantity naturally emerges at the continuum scale as the consequence of\nfrictional sliding at the lower scale. In addition, the effective stress can be\nnaturally worked out from the grain to grain contact law embedded in the model\nwithout being subjected to any interpretation. This, in our opinion, is a\ncloser representation of unsaturated soil behavior, compared to existing\ncontinuum approaches that map everything onto a single stress-strain\nrelationship. In this paper, the framework is presented in its simplest form\nthat takes into account sliding on a single orientation. Grain to grain contact\nlaw with capillary effects is used for the demonstration of the concept, and\nthe technical details behind it. Generalization of the framework for better\nrepresentation of unsaturated soil behavior will also be sketched out."
    },
    {
        "anchor": "Theory of small-polaron band conduction in ultrapure organic crystals: We present a novel theory of charge-carrier mobilities in organic molecular\ncrystals of high purity. Our approach is based on Holstein's original concept\nof small-polaron bands but generalized with respect to the inclusion of\nnonlocal electron-phonon coupling. We derive an explicit expression for the\nmobilities as a function of temperature and, using ab-initio methods to obtain\nthe material parameters, we demonstrate its predictive power by applying it to\nnaphthalene. The results show a remarkably good agreement with experiments and\nprovide new insight into the difference between electron and hole mobilities as\nwell as their peculiar algebraic and anisotropic temperature dependences.",
        "positive": "Simultaneous measurement of the microscopic dynamics and the mesoscopic\n  displacement field in soft systems by speckle imaging: The constituents of soft matter systems such as colloidal suspensions,\nemulsions, polymers, and biological tissues undergo microscopic random motion,\ndue to thermal energy. They may also experience drift motion correlated over\nmesoscopic or macroscopic length scales, \\textit{e.g.} in response to an\ninternal or applied stress or during flow. We present a new method for\nmeasuring simultaneously both the microscopic motion and the mesoscopic or\nmacroscopic drift. The method is based on the analysis of spatio-temporal\ncross-correlation functions of speckle patterns taken in an imaging\nconfiguration. The method is tested on a translating Brownian suspension and a\nsheared colloidal glass."
    },
    {
        "anchor": "Structure of skimmed milk during ultrafiltration process probed by\n  in-situ small angle X-ray scattering: The stability and mechanism underlying the formation of deposits of casein\nmicelles during ultrafiltration process were investigated by small-angle (SAXS)\nand ultra small-angle X-ray scattering(USAXS) which allowed us to probe the\nstructure of skimmed milk on an exceptionally wide range of length scales from\n1 to 2000 nm. Frontal filtration cells were specially developed to probe the\nmicrostructure of deposits by SAXS during the separation process. The results\nrevealed two characteristic length scales for the equilibrium structure with\nradius of gyrations Rg, about 100 nm and 5.6 nm, pertaining to the globular\nmicelles and their non-globular internal structure respectively (Pignon et al.\n2004). In-situ scattering measurements showed that the decrease of permeation\nflows is directly related to the deformation and compression of the micelles in\nthe immediate vicinity of the membrane (figure 1). From absolute SAXS\nintensities, the concentration of the micelles in the deposit can be deduced\nreliably.",
        "positive": "Enhancement of microorganism swimming speed in active matter: We study a swimming undulating sheet in the isotropic phase of an active\nnematic liquid crystal. Activity changes the effective shear viscosity,\nreducing it to zero at a critical value of activity. Expanding in the sheet\namplitude, we find that the correction to the swimming speed due to activity is\ninversely proportional to the effective shear viscosity. Our perturbative\ncalculation becomes invalid near the critical value of activity; using\nnumerical methods to probe this regime, we find that activity enhances the\nswimming speed by an order of magnitude compared to the passive case."
    },
    {
        "anchor": "Structural features and nonlinear rheology of self-assembled networks of\n  cross-linked semiflexible polymers: Disordered networks of semiflexible filaments are common support structures\nin biology. Familiar examples include fibrous matrices in blood clots,\nbacterial biofilms, and essential components of cells and tissues of plants,\nanimals, and fungi. Despite the ubiquity of these networks in biomaterials, we\nhave only a limited understanding of the relationship between their structural\nfeatures and highly strain-sensitive mechanical properties. In this work, we\nperform simulations of three-dimensional networks produced by the irreversible\nformation of crosslinks between linker-decorated semiflexible filaments. We\ncharacterize the structure of networks formed by a simple diffusion-dependent\nassembly process and measure their associated steady-state rheological features\nat finite temperature over a range of applied prestrains that encompass the\nstrain-stiffening transition. We quantify the dependence of network\nconnectivity on crosslinker availability and detail the associated connectivity\ndependence of both linear elasticity and nonlinear strain stiffening behavior,\ndrawing comparisons with prior experimental measurements of the crosslinker\nconcentration-dependent elasticity of actin gels.",
        "positive": "A spring-block model for Barkhausen noise: A simple mechanical spring-block model is introduced for studying\nmagnetization phenomena and in particularly the Barkhausen noise. The model\ncaptures and reproduces the accepted microscopic picture of domain wall\nmovement and pinning. Computer simulations suggest that this model is able to\nreproduce the main characteristics of hysteresis loops and Barkhausen jumps. In\nthe thermodynamic limit the statistics of the obtained Barkhausen jumps follows\nseveral scaling laws, in qualitative agreement with the experimental results.\nThe simplicity of the model and the invoked mechanical analogies makes it\nattractive for computer simulations and pedagogical purposes."
    },
    {
        "anchor": "Towards understanding the behavior of polyelectrolyte surfactant\n  mixtures at the water vapor interface closer to technologically relevant\n  conditions: Polyelectrolyte surfactant mixtures and their interactions with fluid\ninterfaces are an important research field due to their use in technological\napplications. Most of the existing knowledge on these systems is based on\nmodels in which the polyelectrolyte concentration is around 50 times lower than\nthat used in commercial formulations. The present work marks a step to close\nthe gap on the understanding of their behavior under more practically relevant\nconditions. The adsorption of concentrated mixtures of\npoly(diallyldimethylammonium) chloride and sodium N lauroyl N methyltaurate at\nthe water-vapor interface with a crude mixing protocol has been studied by\ndifferent surface tension techniques, Brewster angle microscopy, neutron\nreflectometry, and several bulk characterization techniques. Kinetically\ntrapped aggregates formed during mixing influence the interfacial morphology of\nmixtures produced in the equilibrium one phase region, yet fluctuations in the\nsurface tension isotherm result depending on the tensiometric technique\napplied. At low bulk surfactant concentrations, the free surfactant\nconcentration is very low, and the interfacial composition matches the trend of\nthe bulk complexes, which is a behavior that has not been observed in studies\non more dilute mixtures. Nevertheless, a transition to synergistic\nco-adsorption of complexes and free surfactant is observed at the higher bulk\nsurfactant concentrations studied. This transition appears to be a special\nfeature of these more concentrated mixtures, which deserves attention in future\nstudies of systems with additional components.",
        "positive": "Collective behavior in a granular jet: Emergence of a liquid with zero\n  surface-tension: We perform the analog to the \"water bell\" experiment using non-cohesive\ngranular material. When a jet of granular material, many particles wide,\nrebounds from a fixed cylindrical target, it deforms into a sharply-defined\nsheet or cone with a shape that mimics a liquid with zero surface tension. The\nparticulate nature of granular material becomes apparent when the number of\nparticles in the cross-section of the jet is decreased and the emerging sheets\nand cones broaden and gradually disintegrate into a broad spray. This\nexperiment has its counterpart in the behavior of the quark-gluon plasma\ngenerated by collisions of gold ions at the Relativistic Heavy Ion Collider.\nThere a high density of inter-particle collisions gives rise to collective\nbehavior that has also been described as a liquid."
    },
    {
        "anchor": "Density-functional theory for attraction between like-charged plates: We study the interactions between two negatively charged macroscopic surfaces\nconfining positive counterions. A density-functional approach is introduced\nwhich, besides the usual mean-field interactions, takes into account the\ncorrelations in the positions of counterions. The excess free energy is derived\nin the framework of the Debye-H{\\\"u}ckel theory of the one-component plasma,\nwith the homogeneous density replaced by a weighted density. The minimization\nof the total free energy yields the density profile of the microions. The\npressure is calculated and compared with the simulations and the results\nderived from integral equations theories. We find that the interaction between\nthe two plates becomes attractive when their separation distance is\nsufficiently small and the surface charge density is larger than a threshold\nvalue.",
        "positive": "Measurement of the acoustic radiation force on a sphere embedded in a\n  soft solid: The acoustic radiation force exerted on a small sphere located at the focus\nof an ultrasonic beam is measured in a soft gel. It is proved to evolve\nquadratically with the local amplitude of the acoustic field. Strong\noscillations of the local pressure are observed and attributed to an acoustic\nFabry-P{\\'e}rot effect between the ultrasonic emitter and the sphere. Taking\nthis effect into account with a simple model, a quantitative link between the\nradiation force and the acoustic pressure is proposed and compared to\ntheoretical predictions in the absence of dissipation. The discrepancy between\nexperiment and theory suggests that dissipative effects should be taken into\naccount for fully modeling the observations."
    },
    {
        "anchor": "Enhanced roughness of lipid membranes caused by external electric fields: The behavior of lipid membranes in the presence of an external electric field\nis studied and used to examine the influence of such fields on membrane\nparameters such as roughness and show that for a micro sized membrane,\nroughness grows as the field increases. The dependence of bending rigidity on\nthe electric field is also studied and an estimation of thickness of the\naccumulated charges around lipid membranes in a free-salt solution is\npresented.",
        "positive": "Multiple stalk formation as a pathway of defect-induced membrane fusion: We propose that the first stage of membrane fusion need not be the formation\nof a single stalk. Instead, we consider a scenario for defect-induced membrane\nfusion that proceeds cooperatively via multiple stalk formation. The defects\n(stalks or pores) attract each other via membrane-mediated capillary\ninteractions that result in a condensation transition of the defects. The\nresulting dense phase of stalks corresponds to the so-called fusion\nintermediate."
    },
    {
        "anchor": "Topological Defects in Size-Dispersed Solids: We study the behavior of the topological defects in the inherent structures\nof a two-dimensional binary Lennard-Jones system as the size dispersity varies.\nWe find that topological defects arising from the particle size dispersity are\nresponsible for destabilizing the solid as follows: (i) for particle density\n$\\rho \\leq 0.9$, the solid melts through intermediate states of decreasing\nhexatic order arising from the proliferation of unbounded dislocations, (ii)\nfor $\\rho > 0.9$, the dislocations form grain boundaries, dividing the system\ninto micro-crystallites and destroying the translational and orientational\norder.",
        "positive": "Exotic Topology in Ordinary Soft Matter: Hydrodynamics is shown to induce non-Hermitian topological phenomena in\nordinary, passive soft matter. This is demonstrated for the first time by\nsubjecting a 2D elastic lattice to a low-Reynolds viscous flow. The interplay\nof hydrodynamics and elasticity splits Dirac cones into bulk Fermi arcs,\npairing exceptional points with opposite half-integer topological charges. The\nbulk Fermi arc is a generic hallmark of the system exhibited in all lattice and\nflow symmetries. Analytic model and simulations explain how the emergent\nsingularities shape the spectral bands and give rise to a web of van Hove\nsingularity lines in the density of states. The present findings suggest that\nnon-Hermitian physics can be explored in a broad class of ordinary soft matter,\nliving and artificial alike, opening avenues for topology-based technology in\nthis regime."
    },
    {
        "anchor": "Thermodynamics of sustaining gases in the roughness of submerged\n  superhydrophobic surfaces: Rough surfaces submerged in a liquid can remain almost dry if the liquid does\nnot fully wet the roughness and gases are sustained in roughness grooves. Such\npartially dry surfaces can help reduce drag or enhance boiling. Gases sustained\nin roughness grooves would be composed of air and the vapor phase of the liquid\nitself. The thermodynamics of sustaining vapor was considered in a prior work\n[Patankar, Soft Matter, 2010, 6:1613]. Here, the thermodynamics of sustaining\ngases (e.g. air) is considered. Governing equations are presented along with a\nsolution methodology to determine a critical condition to sustain gases. The\ncritical roughness scale to sustain gases is estimated for different degrees of\nsaturation of gases dissolved in the liquid. It is shown that roughness\nspacings of less than a micron are essential to sustain gases on surfaces\nsubmerged in water at atmospheric pressure. This is consistent with prior\nempirical data.",
        "positive": "Maxwell stress in fluid mixtures: We examine the structure of Maxwell stress in binary fluid mixtures under an\nexternal electric field and discuss its consequence. In particular, we show\nthat, in immiscible blends, it is intimately related to the statistics of\ndomain structure. This leads to a compact formula, which may be useful in the\ninvestigation of electro-rheological effects in such systems. The stress tensor\ncalculated in a phase separated fluid under a steady electric field is in a\ngood agreement with recent experiments."
    },
    {
        "anchor": "Programming bistability in geometrically perturbed mechanical\n  metamaterials: Mechanical metamaterials capable of large deformations are an emerging\nplatform for functional devices and structures across scales. Bistable designs\nare particularly attractive since they endow a single object with two\nconfigurations that display distinct shapes, properties and functionalities. We\npropose a strategy that takes a common (non-bistable) metamaterial design and\ntransforms it into a bistable one, specifically, by allowing for irregular\npatterns through geometric perturbations of the unit cell and by leveraging the\nintercell constraints inherent to the large deformation response of\nmetamaterials. We exemplify this strategy by producing a design framework for\nbistable planar kirigami metamaterials starting from the canonical\nrotating-squares pattern. The framework comprises explicit design formulas for\ncell-based kirigami with unprecedented control over the shape of the two stable\nstates, and an optimization methodology that allows for efficient tailoring of\nthe geometric features of the designs to achieve target elastic properties as\nwell as shape change. The versatility of this framework is illustrated through\na wide variety of examples, including non-periodic designs that achieve two\narbitrarily-shaped stable states. Quantitative and qualitative experiments,\nfeaturing prototypes with distinct engineering design details, complement the\ntheory and shine light on the strengths and limitations of our design approach.\nThese results show how to design bistable metamaterials from non-bistable\ntemplates, paving the way for further discovery of bistable systems and\nstructures that are not simply arrangements of known bistable units.",
        "positive": "Anomalous wave reflection from the interface of two strongly nonlinear\n  granular media: Granular materials exhibit a strongly nonlinear behaviour affecting the\npropagation of information in the medium. Dynamically self-organized strongly\nnonlinear solitary waves are the main information carriers in granular chains.\nHere we report the first experimental observation of the dramatic change of\nreflectivity from the interface of two granular media triggered by a noncontact\nmagnetically induced initial precompression. It may be appropriate to name this\nphenomenon the \"acoustic diode\" effect. Based on numerical simulations, we\nexplain this effect by the high gradient of particle velocity near the\ninterface."
    },
    {
        "anchor": "Geometric localization in supported elastic struts: Localized deformation patterns are a common motif in morphogenesis and are\nincreasingly finding widespread applications in materials science, for instance\nas memory devices. Here we describe the emergence of spatially localized\ndeformations in a minimal mechanical system by exploring the impact of growth\nand shear on the conformation of a semi-flexible filament connected to a\npliable shearable substrate. We combine numerical simulations of a discrete rod\nmodel with theoretical analysis of the differential equations recovered in the\ncontinuum limit to quantify (in the form of scaling laws) how geometry,\nmechanics, and growth act together to give rise to such localized structures in\nthis system. We find that spatially localized deformations along the filament\nemerge for intermediate shear modulus and increasing growth. Finally, we use\nexperiments on a 3D printed multi-material model system to demonstrate that\nexternal control of the amount of shear and growth regulates the spatial extent\nof the localized strain texture.",
        "positive": "Jamming phase diagram for frictional particles: The non-equilibrium transition from a fluid-like state to a disordered\nsolid-like state, known as the jamming transition, occurs in a wide variety of\nphysical systems, such as colloidal suspensions and molecular fluids, when the\ntemperature is lowered or the density increased. Shear stress, as temperature,\nfavors the fluid-like state, and must be also considered to define the system\n'jamming phase diagram' [1-4]. Frictionless athermal systems [1], for instance,\ncan be described by the zero temperature plane of the jamming diagram in the\ntemperature, density, stress space. Here we consider the jamming of athermal\nfrictional systems [8-13] such as granular materials, which are important to a\nnumber of applications from geophysics to industry. At constant volume and\napplied shear stress[1, 2], we show that while in absence of friction a system\nis either fluid-like or jammed, in the presence of friction a new region in the\ndensity shear-stress plane appears, where new dynamical regimes are found. In\nthis region a system may slip, or even flow with a steady velocity for a long\ntime in response to an applied stress, but then eventually jams. Jamming in\nnon-thermal frictional systems is described here by a phase diagram in the\ndensity, shear-stress and friction space."
    },
    {
        "anchor": "Binary fluid demixing: The crossover region: By performing lattice Boltzmann simulations of a binary mixture, we\nscrutinize the dynamical scaling hypothesis for the spinodal decomposition of\nbinary mixtures for the crossover region, i.e. the region of parameters in the\ngrowth curve where neither inertia nor viscous forces dominate the coarsening\nprocess. Our results give no evidence for a breakdown of scaling in this\nregion, as might arise if the process were limited by molecular scale physics\nat the point of fluid pinch-off between domains. A careful data analysis allows\nus to refine previous estimates on the width of the crossover region which is\nsomewhat narrower than previously reported.",
        "positive": "Hierarchical structure of the energy landscape in the Voronoi model of\n  dense tissue: The Voronoi model is a popular tool for studying confluent living tissues. It\nexhibits an anomalous glassy behavior even at very low temperatures or weak\nactive self-propulsion, and at zero temperature the model exhibits a disordered\nsolid structure with no evidence of a rigidity transition. Here we investigate\nthe properties of the energy landscape in this limit. We find two disordered\nsolid phases that have similar structural features but that differ in the\nultrametricity of their energy landscapes; the crossover between these two\nstates shares phenomenological properties with a Gardner transition. We further\nhighlight how the metric used to calculate distances between configurations\ninfluences the ability to detect hierarchical arrangements of basins in the\nenergy landscape."
    },
    {
        "anchor": "First evidence of anisotropic quenched disorder effects on a smectic\n  liquid crystal confined in porous silicon: We present a neutron scattering analysis of the structure of the smectic\nliquid crystal octylcyanobiphenyl (8CB) confined in one-dimensional nanopores\nof porous silicon films (PS). The smectic transition is completely suppressed,\nleading to the extension of a short-range ordered smectic phase aligned along\nthe pore axis. It evolves reversibly over an extended temperature range, down\nto 50 K below the \\textit{N-SmA} transition in pure 8CB. This behavior strongly\ndiffers from previous observations of smectics in different one-dimensional\nporous materials. A coherent picture of this striking behavior requires that\nquenched disorder effects are invoked. The strongly disordered nature of the\ninner surface of PS acts as random fields coupling to the smectic order. The\none-dimensionality of PS nano-channels offers new perspectives on quenched\ndisorder effects, which observation has been restricted to homogeneous random\nporous materials so far.",
        "positive": "Dynamics of localized particles from density functional theory: A fundamental assumption of the dynamical density functional theory (DDFT) of\ncolloidal systems is that a grand-canonical free energy functional may be\nemployed to generate the thermodynamic driving forces. Using one-dimensional\nhard-rods as a model system we analyze the validity of this key assumption and\nshow that unphysical self-interactions of the tagged particle density fields,\narising from coupling to a particle reservoir, are responsible for the\nexcessively fast relaxation predicted by the theory. Moreover, our findings\nsuggest that even employing a canonical functional would not lead to an\nimprovement for many-particle systems, if only the total density is considered.\nWe present several possible schemes to suppress these effects by incorporating\ntagged densities. When applied to confined systems we demonstrate, using a\nsimple example, that DDFT neccessarily leads to delocalized tagged particle\ndensity distributions, which do not respect the fundamental geometrical\ncontraints apparent in Brownian dynamics simulation data. The implication of\nthese results for possible applications of DDFT to treat the glass transition\nare discussed."
    },
    {
        "anchor": "Charge regulation of weak interacting polyelectrolytes: We introduce a generalized non-uniform mean-field formalism to describe the\ndissociation of weak rod-like polyelectrolytes (PEs). Our approach allows for\ntwo-sublattice symmetry breaking which in titration curves is associated with a\nplateau for intermediate dissociation degrees. We first test our method in the\ncase of a single weak PE by comparison with exact enumeration studies and show\nthat it gives quantitatively accurate results for the dissociation degree in\nthe full range of pH values, and in specific performs much better than the\nnearest-neighbor approximation (where exact solutions are possible). We then\nstudy charge regulation of the coupled system of a weak polyacid and a weak\npolybase as a function of their mutual distance, which has some relevance for\nPE-multilayer formation and for PE complexation. An intricate interplay of the\ndegree of dissociation and the effective interaction between the PEs as a\nfunction of their mutual distance is found.",
        "positive": "Elasticity of soft particles and colloids near Random Close Packing: Assemblies of purely repulsive and frictionless particles, such as emulsions\nor hard spheres, display very curious properties near their jamming transition,\nwhich occurs at the random close packing for mono-disperse spheres. Although\nsuch systems do not contain the long and cross-linked polymeric chains\ncharacterizing a rubber, they behave macroscopically in a similar way: the\nshear modulus $G$ can become infinitely smaller than the bulk modulus $B$.\nAfter reviewing recent theoretical results on the structure of such packing (in\nparticular their coordination) I will propose an explanation for the observed\nscaling of the elastic moduli, and explain why the arguments both apply to soft\nand hard particles."
    },
    {
        "anchor": "Edible meta-atoms: Metamaterials are artificial structures with unusual and superior properties\nthat come from their carefully designed building blocks -- also called\nmeta-atoms. Metamaterials have permeated large swatches of science, including\nelectromagnetics and mechanics. Although metamaterials hold the promise for\nrealizing technological advances, their potential to enhance interactions\nbetween humans and materials has remained unexplored. Here, we devise\nmeta-atoms with tailored fracture properties to control mouthfeel sensory\nexperience. Using chocolate as a model material, we first use meta-atoms to\ncontrol the fracture anisotropy and the number of cracks and demonstrate that\nthese properties are captured in mouthfeel experience. We further use topology\noptimization to rationally design edible meta-atoms with maximally anisotropic\nfracture strength. Our work opens avenues for the use of meta-atoms and\nmetamaterials to control fracture and to enhance human-matter interactions.",
        "positive": "Self-solidifying active droplets showing memory-induced chirality: Most synthetic microswimmers do not reach the autonomy of their biological\ncounterparts in terms of energy supply and diversity of motion. Here we report\nthe first all-aqueous droplet swimmer powered by self-generated polyelectrolyte\ngradients, which shows memory-induced chirality while self-solidifying. An\naqueous solution of surface tension-lowering polyelectrolytes self-solidifies\non the surface of acidic water, during which polyelectrolytes are gradually\nemitted into the surrounding water and induce linear self-propulsion via\nspontaneous symmetry breaking. The low diffusion coefficient of the\npolyelectrolytes leads to long-lived chemical trails which cause memory effects\nthat drive a transition from linear to chiral motion without requiring any\nimposed symmetry breaking. The droplet swimmer is capable of highly efficient\nremoval (up to 85%) of uranium from aqueous solutions within 90 min, benefiting\nfrom self-propulsion and flow-induced mixing. Our results provide a route to\nfueling self-propelled agents which can autonomously perform chiral motion and\ncollect toxins."
    },
    {
        "anchor": "Theoretical Reconstruction of Realistic Dynamics of Highly\n  Coarse-Grained cis-1,4-Polybutadiene Melts: The theory to reconstruct the atomistic-level chain diffusion from the\naccelerated dynamics that is measured in mesoscale simulations of the\ncoarse-grained system, is applied here to the dynamics of cis-1,4-Polybutadiene\nmelts where each chain is described as a soft interacting colloidal particle.\nThe rescaling formalism accounts for the corrections in the dynamics due to the\nchange in entropy and the change in friction that are a consequence of the\ncoarse-graining procedure. By including these two corrections the dynamics is\nrescaled to reproduce the realistic dynamics of the system described at the\natomistic level. The rescaled diffusion coefficient obtained from mesoscale\nsimulations of coarse-grained cis-1,4-Polybutadiene melts shows good agreement\nwith data from united atom simulations performed by Tsolou et al. The derived\nmonomer friction coefficient is used as an input to the theory for cooperative\ndynamics that describes the internal dynamics of a polymer moving in a\ntransient regions of slow cooperative motion in a liquid of macromolecules.\nTheoretically predicted time correlation functions show good agreement with\nsimulations in the whole range of length and time scales in which data are\navailable. The theory provides, from data of mesoscale simulations of soft\nspheres, the correct atomistic-level dynamics, having as solo input static\nquantities.",
        "positive": "Theoretical study of phase behaviour of DLVO model for lysozyme and\n  $\u03b3$-crystalline aqueous electrolyte solutions: Mean spherical approximation (MSA), second-order Barker-Henderson (BH)\nperturbation theory and thermodynamic perturbation theory (TPT) for associating\nfluids in combination with BH perturbation theory are applied to the study of\nthe structural properties and phase behaviour of the\nDerjaguin-Landau-Verwey-Overbeek (DLVO) model of lysozyme and\n$\\gamma$-cristalline aqueous electrolyte solutions. Predictions of the MSA for\nthe structure factors are in good agreement with the corresponding computer\nsimulation predictions. The agreement between theoretical results for the\nliquid-gas phase diagram and the corresponding results of the experiment and\ncomputer simulation is less satisfactory, with predictions of the combined\nBH-TPT approach being the most accurate."
    },
    {
        "anchor": "Some observations on the renormalization of membrane rigidity by\n  long-range interactions: We consider the renormalization of the bending and Gaussian rigidity of model\nmembranes induced by long-range interactions between the components making up\nthe membrane. In particular we analyze the effect of a finite membrane\nthickness on the renormalization of the bending and Gaussian rigidity by\nlong-range interactions. Particular attention is paid to the case where the\ninteractions are of a van der Waals type.",
        "positive": "How water meets a very hydrophobic surface: Is there a low-density region ('gap') between water and a hydrophobic\nsurface? Previous X-ray/neutron reflectivity results have been inconsistent\nbecause the effect (if any) is sub-resolution for the surfaces studied. We have\nused X-ray reflectivity to probe the interface between water and more\nhydrophobic smooth surfaces. The depleted region width increases with contact\nangle and becomes larger than the resolution, allowing definitive measurements.\nLarge fluctuations are predicted at this interface; however, we find that their\ncontribution to the interface roughness is too small to measure."
    },
    {
        "anchor": "Scaling between Structural Relaxation and Particle Caging in a Model\n  Colloidal Gel: In polymers melts and supercooled liquids, the glassy dynamics is\ncharacterized by the rattling of monomers or particles in the cage formed by\ntheir neighbors. Recently, a direct correlation in such systems, described by a\nuniversal scaling form, has been established between the rattling amplitude and\nthe structural relaxation time. In this paper we analyze the glassy dynamics\nemerging from the formation of a persistent network in a model colloidal gel at\nvery low density. The structural relaxation time of the gel network is compared\nwith the mean squared displacement at short times, corresponding to the\nlocalization length associated to the presence of energetic bonds.\nInterestingly, we find that the same type of scaling as for the dense glassy\nsystems holds. Our findings well elucidate the strong coupling between the\ncooperative rearrangements of the gel network and the single particle\nlocalization in the structure. Our results further indicate that the scaling\ncaptures indeed fundamental physical elements of glassy dynamics.",
        "positive": "Static and Dynamic Properties of Trapped Fermionic Tonks-Girardeau Gases: We investigate some exact static and dynamic properties of one-dimensional\nfermionic Tonks-Girardeau gases in tight de Broglie waveguides with attractive\np-wave interactions induced by a Feshbach resonance. A closed form solution for\nthe one-body density matrix for harmonic trapping is analyzed in terms of its\nnatural orbitals, with the surprising result that for odd, but not for even,\nnumbers of fermions the maximally occupied natural orbital coincides with the\nground harmonic oscillator orbital and has the maximally allowed fermionic\noccupancy of unity. The exact dynamics of the trapped gas following turnoff of\nthe p-wave interactions are explored."
    },
    {
        "anchor": "Evidence of growing spatial correlations during the aging of glassy\n  glycerol: We have measured, as a function of the age $t_a$, the aging of the nonlinear\ndielectric susceptibility $\\chi_3$ of glycerol below the glass transition.\nWhereas the linear susceptibility can be accurately accounted for in terms of\nan age dependent relaxation time $\\tau_{\\alpha}(t_a)$, this scaling breaks down\nfor $\\chi_3$, suggesting an increase of the amplitude of $\\chi_3$. This is a\nstrong indication that the number $N_{corr}$ of molecules involved in\nrelaxation events increases with $t_a$. For $T=0.96 \\times T_g$, we find that\n$N_{corr}$ increases by $\\sim 10%$ when $t_a$ varies from $1\\mathrm{ks}$ to\n$100\\mathrm{ks}$. This sheds new light on the relation between length scales\nand time scales in glasses.",
        "positive": "A geometrically controlled rigidity transition in a model for confluent\n  3D tissues: The origin of rigidity in disordered materials is an outstanding open problem\nin statistical physics. Previously, a class of 2D cellular models has been\nshown to undergo a rigidity transition controlled by a mechanical parameter\nthat specifies cell shapes. Here, we generalize this model to 3D and find a\nrigidity transition that is similarly controlled by the preferred surface area:\nthe model is solid-like below a dimensionless surface area of\n$s_0^\\ast\\approx5.413$, and fluid-like above this value. We demonstrate that,\nunlike jamming in soft spheres, residual stresses are necessary to create\nrigidity. These stresses occur precisely when cells are unable to obtain their\ndesired geometry, and we conjecture that there is a well-defined minimal\nsurface area possible for disordered cellular structures. We show that the\nbehavior of this minimal surface induces a linear scaling of the shear modulus\nwith the control parameter at the transition point, which is different from the\nscaling observed in particulate matter. The existence of such a minimal surface\nmay be relevant for biological tissues and foams, and helps explain why cell\nshapes are a good structural order parameter for rigidity transitions in\nbiological tissues."
    },
    {
        "anchor": "Nanostars planarity modulates the elasticity of DNA hydrogels: In analogy with classic rigidity problems of networks and frames, the elastic\nproperties of hydrogels made of DNA nanostars (DNAns) are expected to strongly\ndepend on the precise geometry of their building blocks. However, it is\ncurrently not possible to determine DNAns shape experimentally. Computational\ncoarse-grained models that can retain the correct geometry of DNA nanostars and\naccount for the bulk properties observed in recent experiments could provide\nmissing insights. In this study, we perform metadynamics simulations to obtain\nthe preferred configuration of three-armed DNA nanostars simulated with the\noxDNA model. Based on these results we introduce a coarse-grained computational\nmodel of nanostars that can self assemble into complex three dimensional\npercolating networks. We compare two systems with different designs, in which\neither planar or non-planar nanostars are used. Structural and network analysis\nreveal completely different features for the two cases, leading to two\ncontrasting elastic properties. The mobility of molecules is larger in the\nnon-planar case, which is consistent with a lower viscosity measured from\nGreen-Kubo simulations in equilibrium. To the best of our knowledge, this is\nthe first work connecting the geometry of DNAns with the bulk rheological\nproperties of DNA hydrogels and may inform the design of future DNA based\nmaterials.",
        "positive": "Structural studies of the bond-orientational order and hexatic-smectic\n  transition in liquid crystals of various compositions: We report on X-ray studies of freely suspended hexatic films of three\ndifferent liquid crystal compounds. By applying angular X-ray cross-correlation\nanalysis (XCCA) to the measured diffraction patterns the parameters of the\nbond-orientational (BO) order in the hexatic phase were directly determined.\nThe temperature evolution of the BO order parameters was analyzed on the basis\nof the multicritical scaling theory (MCST). Our results confirmed the validity\nof the MCST in the whole temperature range of existence of the hexatic phase\nfor all three compounds. The temperature dependence of the BO order parameters\nin the vicinity of the hexatic-smectic transition was fitted by a conventional\npower law with a critical exponent $\\beta\\approx0.1$ of extremely small value.\nWe found that the temperature dependence of higher order harmonics of the BO\norder scales as the powers of the first harmonic, with exponent equal to\nharmonic number. This indicates a nonlinear coupling of the BO order parameters\nof different order. It is shown that compounds of various composition,\npossessing different phase sequences, display the same thermodynamic behavior\nin the hexatic phase and in the vicinity of the smectic-hexatic phase\ntransition."
    },
    {
        "anchor": "Some fundamentals of adhesion in synthetic adhesives: Various adhesion mechanisms that have been understood in the field of\nsynthetic adhesives are described and these are linked with situations relevant\nto fouling issues. The review mainly deals with mechanical aspects of adhesion\nphenomena, with an emphasis on the role of the elasticity of the bodies, called\nsubstrata, attached by adhesive. The consequences of thin film geometry of the\nadhesive material are described, such as various heterogeneous deformations\nupon traction. The importance of the bonding process is discussed, as well as\nsome examples of non-wetting surfaces. As seen from a distance, the adhesive\nlayer is merely one interface; Some basic ideas of fracture mechanics are\nprovided and in particular, the behavior of layered systems is discussed.\nRolling sticky objects and peeled (flexible) adhesive tapes display similar\nmechanisms and it is shown how they differ from the normal separation of rigid\nbodies. Some issues directly related to fouling issues are also discussed, such\nas forces and torques acting on shells, the advantages of gregarious settlement\nbehavior and concepts for fouling release and antifouling.",
        "positive": "Nonequilibrium capillary self-assembly: Macroscopic objects supported by surface tension at the fluid interface can\nself-assemble through the action of capillary forces arising from interfacial\ndeformations. The resulting self-assembled structures are ordered but remain\ntrapped in one of potentially many metastable states in the capillary energy\nlandscape. This contrasts with microscopic colloidal self-assembly where\nthermal fluctuations excite transitions between geometrically distinct\nground-state configurations. We herein utilize supercritical Faraday waves to\ndrive structural rearrangements between metastable states of few-particle\nclusters of millimetric spheres bound by capillary attractions at the fluid\ninterface. Using a combination of experiments and theoretical modelling, we\ndemonstrate how the occupation probabilities of different cluster topologies\nand transition statistics are controlled by the level of the vibrational\nforcing and the spatial extent of long-range capillary forces. Our results\ndemonstrate how self-assembly dynamics and statistics may be manipulated across\nscales by controlling the strength of fluctuations and by tuning the properties\nof the particle interaction-potential."
    },
    {
        "anchor": "Clustering, intermittency and scaling for passive particles on\n  fluctuating surfaces: We show that a scaling approach successfully characterizes clustering and\nintermittency in space and time, in systems of noninteracting particles driven\nby fluctuating surfaces. We study both the steady state and the approach to it,\nfor passive particles sliding on one-dimensional Edwards-Wilkinson or\nKardar-Parisi-Zhang surfaces, with particles moving either along or against the\ngrowth direction in the latter case. Extensive numerical simulations are\nsupplemented by analytical results for a sticky slider model in which particles\ncoalesce when they meet. Results for single particle displacement versus time\nshow to what extent particle dynamics is slaved to the surface, while scaling\nproperties of the probability distribution of the separation of two particles\nhave important implications for replica symmetry breaking for a pair of\ntrajectories. For the many-particle system, clustering in steady state is\nstudied via moments of particle number fluctuations in a single stretch,\nrevealing different degrees of spatial multiscaling with different driving.\nTemporal intermittency in steady state is established by showing that the\nscaled flatness diverges. Finally we consider the approach to the steady state,\nand study both the flatness and the evolution of equal-time correlation\nfunctions, as in coarsening of phase ordering systems. Our studies give clear\nevidence for a simple scaling description of the approach to steady state, with\na diverging length scale. An investigation of aging properties reveals that\nflatness is nonmonotonic in time with two distinct branches, and that a scaling\ndescription holds for each one.",
        "positive": "Molecular relaxations in supercooled liquid and glassy states of\n  amorphous gambogic acid: dielectric spectroscopy, calorimetry and theoretical\n  approach: The relaxation dynamics and thermodynamic properties of supercooled and\nglassy gambogic acid are investigated using both theory and experiment. We\nmeasure the temperature dependence of the relaxation times in three polymorphs\n(alpha-, beta-, and gamma-form). To gain insight into the relaxation processes,\nwe propose a theoretical approach to quantitatively understand nature of these\nthree relaxations. The alpha-relaxation captures cooperative motions of\nmolecules while the beta-process is mainly governed by local dynamics of a\nsingle molecule within the cage formed by its nearest neighbors. Based on\nquantitative agreement between theory and experimental data, our calculations\nclearly indicate that the beta-process is a precursor of the structural\nrelaxation and intramolecular motions are responsible for the gamma-relaxation.\nMoreover, the approach is exploited to study effects of the heating process on\nalpha relaxation. We find that the heating rate varies logarithmically with Tg\nand 1000/Tg. These variations are qualitatively consistent with many prior\nstudies."
    },
    {
        "anchor": "Transition from viscoelastic to fracture-like peeling of\n  pressure-sensitive adhesives: We investigate the process of the slow unrolling of a roll of typical\npressure-sensitive adhesive, Scotch tape, under its own weight. Probing the\npeeling velocities down to nm/s resolution, which is three orders of magnitudes\nlower than earlier measurements, we find that the speed is still non-zero.\nMoreover, the velocity is correlated to the relative humidity. A humidity\nincrease leads to water uptake, making the adhesive weaker and easier to peel.\nAt very low humidity, the adhesive becomes so stiff that it mainly responds\nelastically, leading to a peeling process akin to interfacial fracture. We\nprovide a quantitative understanding of the peeling velocity in the two\nregimes.",
        "positive": "Size and shape fluctuations of ultrasoft colloids: Ultrasoft colloidal particle fluctuates due to its flexibility. Such\nfluctuation is essential for colloidal structure and dynamics, but is\nchallenging to quantify experimentally. We use dendrimers as a model system to\nstudy the fluctuation of ultrasoft colloids. By considering the dynamic\npolydispersity in the small-angle neutron scattering (SANS) model, and\nintroducing the fluctuation of invasive water into the contrast in SANS, we\nreveal the fluctuating amplitudes of the size and shape of the dendrimer of\ngeneration 6 at finite concentrations. The size fluctuation is suppressed while\nthe shape fluctuation increases as the weight fraction of dendrimers passes\n11%. With neutron spin echo data, we suggest that such crossover originates\nfrom the competition between the inter- and intra-particle dynamics. Further\ninvestigation on lower-generation samples shows a contrary result, which\nsuggests a structural basis for these dynamic phenomena."
    },
    {
        "anchor": "Large-strain poroelastic plate theory for polymer gels with applications\n  to swelling-induced morphing of composite plates: We derive a large-strain plate model that allows to describe transient,\ncoupled processes involving elasticity and solvent migration, by performing a\ndimensional reduction of a three-dimensional poroelastic theory. We apply the\nmodel to polymer gel plates, for which a specific kinematic constraint and\nconstitutive relations hold. Finally, we assess the accuracy of the plate model\nwith respect to the parent three-dimensional model through two numerical\nbenchmarks, solved by means of the finite element method. Our results show that\nthe theory offers an efficient computational framework for the study of\nswelling-induced morphing of composite gel plates.",
        "positive": "Observation of Spider Silk by Femtosecond Pulse Laser Second Harmonic\n  Generation Microscopy: An asymmetric \\b{eta}-sheet structure of spider silk is said to induce\noptical second harmonic generation. In this paper, using an in-house\nnon-scanning type femtosecond pulse laser second harmonic generation\nmicroscope, we characterized the behavior of the \\b{eta}-sheet of spider silk\nunder an applied external force. The orientation of the \\b{eta}-sheets was more\nunidirectional when the silk was extended. One of the origins of the high\nmechanical strength of the dragline is suggested to be the physical arrangement\nof its \\b{eta}-sheets."
    },
    {
        "anchor": "Interaction of Active Janus Particles with Passive Tracers: In this study, we investigated the motion of active SiO2-Pt Janus particles\nin the 2D bath of smaller silica tracers dispersed in varying areal densities.\nThe effect on the organization of the tracer particles around the active JPs\nwas also explored. Our experiments indicate that the interaction between the\ntracers and the active JPs mainly depend on the nature of collision marked by\nthe duration of contact. For all the concentration regimes, we have shown that\nthe short time collisions do not have significant impact on the motion of\nactive JPs, however, during moderate/long-time collisions tracer(s) can lead to\na significant change in active JPs motion and even cause them to rotate. In the\nconcentrated regime, our experiments reveal the emergence of a novel\norganizational behavior of the passive tracers on the trailing Pt and the\nleading SiO2 with a strong dependence on the nature of collision.",
        "positive": "Accuracy and speed of elongation in a minimal model of DNA replication: Being a dual purpose enzyme, the DNA polymerase is responsible for elongation\nof the newly formed DNA strand as well as cleaving the erroneous growth in case\nof a misincorporation. The efficiency of replication depends on the\ncoordination of the polymerization and exonuclease activity of DNA polymerase.\nHere we propose and analyze a minimal kinetic model of DNA replication and\ndetermine exact expressions for the velocity of elongation and the accuracy of\nreplication. We first analyze the case without exonuclease activity. In that\ncase, accuracy is determined by a kinetic competition between stepping and\nunbinding, with discrimination between correct and incorrect nucleotides in\nboth transitions. We then include exonuclease activity and ask how different\nmodes of additional discrimination in the exonuclease pathway can improve the\naccuracy while limiting the detrimental effect of exonuclase on the speed of\nreplication. In this way, we ask how the kinetic parameters of the model have\nto be set to coordinate the two activities of the enzyme for high accuracy and\nhigh speed. The analysis also shows that the design of a replication system\ndoes not universally have to follow the speed-accuracy trade-off rule, although\nit does in the biologically realized parameter range. The accuracy of the\nprocess is mainly controlled by the crucial role of stepping after erroneous\nincorporation, which has impact on both polymerase and exonuclease activities\nof DNA polymerase."
    },
    {
        "anchor": "Unzipping DNA from the condensed globule state--Effects of unraveling: We study theoretically the unzipping of a double stranded DNA from a\ncondensed globule state by an external force. At constant force, we find that\nthe double stranded DNA unzips an at critical force Fc and the number of\nunzipped monomers M goes as M~(Fc-F)^{-3}, for both the homogeneous and\nheterogeneous double stranded DNA sequence. This is different from the case of\nunzipping from an extended coil state in which the number of unzipped monomers\nM goes as M~(Fc-F)^{-chi}, where the exponent chi is either 1 or 2 depending on\nwhether the double stranded DNA sequence is homogeneous or heterogeneous\nrespectively. In the case of unzipping at constant extension, we find that for\na double stranded DNA with a very large number N of base pairs, the force\nremains almost constant as a function of the extension, before the unraveling\ntransition, at which the force drops abruptly to zero. Right at the unraveling\ntransition, the number of base pairs remaining in the condensed globule state\nis still very large and goes as N^{3/4}, in agreement with theoretical\npredictions of the unraveling transition of polymers stretched by an external\nforce.",
        "positive": "Non-equilibrium dynamics of a binary solvent around heated colloidal\n  particles: Using numerical simulations, we study the non-equilibrium coarsening dynamics\nof a binary solvent around spherical colloids in the presence of a temperature\ngradient. The coarsening dynamics following a temperature quench is studied by\nsolving the coupled modified Cahn-Hilliard-Cook equation and the heat diffusion\nequation, which describe the concentration profile and the temperature field,\nrespectively. For the temperature field we apply a suitable boundary condition.\nWe observe the formation of circular layers of different phases around the\ncolloid whereas away from the colloid patterns of spinodal decomposition\npersist. Additionally, we investigate the dependence of the pattern formation\non the quench temperature. Our simulation mimics an experimental system where\nthe colloid is heated by laser illumination. Note that we look at the cooling\nof a solvent with an upper critical temperature, whereas the experimental\nanalogue is the laser-heating of a solvent with a lower critical temperature.\nWe also study a two colloid system. Here, we observe that a bridge of one phase\nforms connecting the two colloids. Also, we study the force acting on the\ncolloids that is generated by the chemical potential gradient."
    },
    {
        "anchor": "Invariance of Structure in an Aging Colloidal Glass: We study concentrated colloidal suspensions, a model system which has a glass\ntransition. The non-equilibrium nature of the glassy state is most clearly\nhighlighted by aging -- the dependence of the system's properties on the time\nelapsed since vitrification. Fast laser scanning confocal microscopy allows us\nto image a colloidal glass and track the particles in three dimensions. We\nanalyze the static structure in terms of tetrahedral packing. We find that\nwhile the aging of the suspension clearly affects its dynamics, none of the\ngeometrical quantities associated with tetrahedra change with age.",
        "positive": "Field-induced structure transformation in electrorheological solids: We have computed the local electric field in a body-centered tetragonal (BCT)\nlattice of point dipoles via the Ewald-Kornfeld formulation, in an attempt to\nexamine the effects of a structure transformation on the local field strength.\nFor the ground state of an electrorheological solid of hard spheres, we\nidentified a novel structure transformation from the BCT to the face-centered\ncubic (FCC) lattices by changing the uniaxial lattice constant c under the hard\nsphere constraint. In contrast to the previous results, the local field\nexhibits a non-monotonic transition from BCT to FCC. As c increases from the\nBCT ground state, the local field initially decreases rapidly towards the\nisotropic value at the body-centered cubic lattice, decreases further, reaching\na minimum value and increases, passing through the isotropic value again at an\nintermediate lattice, reaches a maximum value and finally decreases to the FCC\nvalue. An experimental realization of the structure transformation is\nsuggested. Moreover, the change in the local field can lead to a generalized\nClausius-Mossotti equation for the BCT lattices."
    },
    {
        "anchor": "Effects of trap anisotropy on impurity scattering regime in a Fermi gas: We evaluate the low-lying oscillation modes and the ballistic expansion\nproperties of a harmonically trapped gas of fermionic K40 atoms containing\nthermal Rb87 impurities as functions of the anisotropy of the trap. Numerical\nresults are obtained by solving the Vlasov-Landau equations for the one-body\nphase-space distribution functions and are used to test simple scaling\nAnsatzes. Starting from the gas in a weak impurity-scattering regime inside a\nspherical trap, the time scales associated to motions in the axial and\nazimuthal directions enter into competition as the trap is deformed to an\nelongated cigar-like shape. This competition gives rise to coexistence of\ncollisionless and hydrodynamic behaviors in the low-lying surface modes of the\ngas as well as to a dependence of the aspect ratio of the expanding cloud on\nthe collision time.",
        "positive": "Interface instability in shear banding flow: We report on the spatio-temporal dynamics of the interface in shear-banding\nflow of a wormlike micellar system (cetyltrimethylammonium bromide and sodium\nnitrate in water) during a start-up experiment. Using the scattering properties\nof the induced structures, we demonstrate the existence of an instability of\nthe interface between bands along the vorticity direction. Different regimes of\nspatio-temporal dynamics of the interface are indentified along the stress\nplateau. We build a model based on the flow symetry which qualitatively\ndescribes the observed patterns."
    },
    {
        "anchor": "Observation of two-wave structure in strongly nonlinear dissipative\n  granular chains: In a strongly nonlinear viscous granular chain under conditions of loading\nthat exclude stationary waves (e.g., impact by a single grain) we observe a\npulse that consists of two interconnected but distinct parts. One is a leading\nnarrow \"primary pulse\" with properties similar to a solitary wave in a \"sonic\nvacuum.\" It arises from strong nonlinearity and discreteness in the absence of\ndissipation, but now decays due to viscosity. The other is a broad, much more\npersistent shock-like \"secondary pulse\" trailing the primary pulse and caused\nby viscous dissipation. The medium behind the primary pulse is transformed from\na \"sonic vacuum\" to a medium with finite sound speed. When the rapidly decaying\nprimary pulse dies, the secondary pulse continues to propagate in the \"sonic\nvacuum,\" with an oscillatory front if the viscosity is relatively small, until\nits eventual (but very slow) disintegration. Beyond a critical viscosity there\nis no separation of the two pulses, and the dissipation and nonlinearity\ndominate the shock-like attenuating pulse which now exhibits a nonoscillatory\nfront.",
        "positive": "Experimental evidence of the failure of Jarzynski equality in active\n  baths: Most natural and engineered processes, such as biomolecular reactions,\nprotein folding, and population dynamics, occur far from equilibrium and,\ntherefore, cannot be treated within the framework of classical equilibrium\nthermodynamics. The Jarzynski equality holds the promise to calculate the\nfree-energy difference between two states from the Boltzmann-weighted\nstatistics of the irreversible work done along trajectories arbitrarily out of\nequilibrium. This equality is the subject of intense activity. However, the\napplicability of the Jarzynski equality to systems far from equilibrium such as\nliving matter has not been investigated yet. We present an experimental test of\nthe Jarzynski equality predictions on a paradigmatic physical model, i.e. a\nBrownian particle held in an optical potential, coupled either to a thermal\nbath or to an active bath. While in the thermal bath we find that the Jarzynski\nequality correctly retrieves the free-energy difference from nonequilibrium\nmeasurements, in the active bath the Jarzynski equality fails because of the\npresence of non-Boltzmann statistics. We corroborate our experimental findings\nwith theoretical arguments and numerical simulations."
    },
    {
        "anchor": "The role of body rotation in bacterial flagellar bundling: In bacterial chemotaxis, E. coli cells drift up chemical gradients by a\nseries of runs and tumbles. Runs are periods of directed swimming, and tumbles\nare abrupt changes in swimming direction. Near the beginning of each run, the\nrotating helical flagellar filaments which propel the cell form a bundle. Using\nresistive-force theory, we show that the counter-rotation of the cell body\nnecessary for torque balance is sufficient to wrap the filaments into a bundle,\neven in the absence of the swirling flows produced by each individual filament.",
        "positive": "On the microscopic foundation of dissipative particle dynamics: Mesoscopic particle based fluid models, such as dissipative particle\ndynamics, are usually assumed to be coarse-grained representations of an\nunderlying microscopic fluid. A fundamental question is whether there exists a\nmap from microscopic particles in these systems to the corresponding\ncoarse-grained particles, such that the coarse-grained system has the same bulk\nand transport properties as the underlying system. In this letter, we\ninvestigate the coarse-graining of microscopic fluids using a Voronoi type\nprojection that has been suggested in several studies. The simulations show\nthat the projection fails in defining coarse-grained particles that have a\nphysically meaningful connection to the microscopic fluid. In particular, the\nVoronoi projection produces identical coarse-grained equilibrium properties\nwhen applied to systems with different microscopic interactions and different\nbulk properties."
    },
    {
        "anchor": "Unraveling the glass-like dynamic heterogeneity in ring polymer melts:\n  From semi-flexible to stiff chain: Ring polymers are an intriguing class of polymers with unique physical\nproperties, and understanding their behavior is important for developing\naccurate theoretical models. In this study, we investigate the effect of chain\nstiffness and monomer density on static and dynamic behaviors of ring polymer\nmelts using molecular dynamics simulations. Our first focus is on the\nnon-Gaussian parameter of center of mass displacement as a measure of dynamic\nheterogeneity, which is commonly observed in glass-forming liquids. We find\nthat the non-Gaussianity in the displacement distribution increases with the\nmonomer density and stiffness of the polymer chains, suggesting that excluded\nvolume interactions between centers of mass have a stronger effect on the\ndynamics of ring polymers. We then analyze the relationship between the radius\nof gyration and monomer density for semi-flexible and stiff ring polymers. Our\nresults indicate that the relationship between the two varies with chain\nstiffness, which can be attributed to the competition between repulsive forces\ninside the ring and from adjacent rings. Finally, we study the dynamics of\nbond-breakage virtually connected between the centers of mass of rings to\nanalyze the exchanges of inter-molecular networks of bonds. Our results\ndemonstrate that the dynamic heterogeneity of bond-breakage is coupled with the\nnon-Gaussianity in ring polymer melts, highlighting the importance of\nbond-breaking method in determining the inter-molecular dynamics of ring\npolymer melts. Overall, our study provides insights into the fundamental\nmechanism of ring polymers and sheds light on the factors that govern their\ndynamic behavior.",
        "positive": "Geometrically-tuned channel permeability: We characterize the motion of charged as well as neutral tracers, in an\nelectrolyte embedded in a varying section channel. We exploit a set of\nsystematic approximations that allows us to simplify the problem, yet capturing\nthe essential of the interplay between the geometrical confinement provided by\nthe corrugated channel walls and the electrolyte properties. Our simplified\napproach allows us to characterize the transport properties of corrugated\nchannels when a net flux of tracers is obtained by keeping the extrema of the\nchannel at different chemical potentials. For highly diluted tracer\nsuspensions, we have characterized tracers currents and we have estimated the\nnet electric current which occurs when both positively and negatively charged\ntracers are considered."
    },
    {
        "anchor": "Hamiltonian traffic dynamics in microfluidic-loop networks: Recent microfluidic experiments revealed that large particles advected in a\nfluidic loop display long-range hydrodynamic interactions. However, the\nconsequences of such couplings on the traffic dynamics in more complex networks\nremain poorly understood. In this letter, we focus on the transport of a finite\nnumber of particles in one-dimensional loop networks. By combining numerical,\ntheoretical, and experimental efforts, we evidence that this collective process\noffers a unique example of Hamiltonian dynamics for hydrodynamically\ninteracting particles. In addition, we show that the asymptotic trajectories\nare necessarily reciprocal despite the microscopic traffic rules explicitly\nbreak the time reversal symmetry. We exploit these two remarkable properties to\naccount for the salient features of the effective three-particle interaction\ninduced by the exploration of fluidic loops.",
        "positive": "Phyllotaxis: a framework for foam topological evolution: Phyllotaxis describes the arrangement of florets, scales or leaves in\ncomposite flowers or plants (daisy, aster, sunflower, pinecone, pineapple). As\na structure, it is a geometrical foam, the most homogeneous and densest\ncovering of a large disk by Voronoi cells (the florets), constructed by a\nsimple algorithm: Points placed regularly on a generative spiral constitute a\nspiral lattice, and phyllotaxis is the tiling by the Voronoi cells of the\nspiral lattice. Locally, neighboring cells are organized as three whorls or\nparastichies, labeled with successive Fibonacci numbers. The structure is\nencoded as the sequence of the shapes (number of sides) of the successive\nVoronoi cells on the generative spiral. We show that sequence and organization\nare independent of the position of the initial point on the generative spiral,\nthat is invariant under disappearance ($T2$) of the first Voronoi cell or,\nconversely, under creation of a first cell, that is under growth. This\nindependence shows how a foam is able to respond to a shear stress, notably\nthrough grain boundaries that are layers of square cells slightly truncated\ninto heptagons, pentagons and hexagons, meeting at four-corner vertices,\ncritical points of $T1$ elementary topological transformations."
    },
    {
        "anchor": "Micro-flock patterns and macro-clusters in chiral active Brownian disks: Chiral active particles (or self-propelled circle swimmers) feature a rich\ncollective behavior, comprising rotating macro-clusters and micro-flock\npatterns which consist of phase-synchronized rotating clusters with a\ncharacteristic self-limited size. These patterns emerge from the competition of\nalignment interactions and rotations suggesting that they might occur\ngenerically in many chiral active matter systems. However, although excluded\nvolume interactions occur naturally among typical circle swimmers, it is not\nyet clear if macro-clusters and micro-flock patterns survive their presence.\nThe present work shows that both types of pattern do survive but feature\nstrongly enhance fluctuations regarding the size and shape of the individual\nclusters. Despite these fluctuations, we find that the average micro-flock size\nstill follows the same characteristic scaling law as in the absence of excluded\nvolume interactions, i.e. micro-flock sizes scale linearly with the\nsingle-swimmer radius.",
        "positive": "Active Matter Class with Second-Order Transition to Quasi-Long-Range\n  Polar Order: We introduce and study in two dimensions a new class of dry, aligning, active\nmatter that exhibits a direct transition to orientational order, without the\nphase-separation phenomenology usually observed in this context. Characterized\nby self-propelled particles with velocity reversals and ferromagnetic alignment\nof polarities, systems in this class display quasi-long-range polar order with\ncontinuously-varying scaling exponents and yet a numerical study of the\ntransition leads to conclude that it does not belong to the\nBerezinskii-Kosterlitz-Thouless universality class, but is best described as a\nstandard critical point with algebraic divergence of correlations. We\nrationalize these findings by showing that the interplay between order and\ndensity changes the role of defects."
    },
    {
        "anchor": "kGamma distributions in granular packs: It has been recently pointed out that local volume fluctuations in granular\npackings follow remarkably well a shifted and rescaled Gamma distribution named\nthe kGamma distribution [T. Aste, T. Di Matteo, Phys. Rev. E 77 (2008) 021309].\nIn this paper we confirm, extend and discuss this finding by supporting it with\nadditional experimental and simulation data.",
        "positive": "Ionic blockade in a charged single-file water channel: The classical continuum theories fail to describe the ionic transport in\nAngstrom channels, where conduction deviates from Ohm's law, as attributed to\ndehydration/self-energy barrier and dissociation of Bjerrum ion-pairs in\nprevious work. Here we found that the cations are strongly bound to the surface\ncharge that blockade the ionic transport in a single-file water channel,\ncausing nonlinear current-voltage responses. The presence of free ions\nsignificantly increased the probability of bound ions being released, resulting\nin an ionic current. We found that ionic conduction gradually becomes Ohmic as\nsurface charge density increases, but the conduction amplitude decreased due to\nincreased friction from bound ions. We rationalized the ionic transport by 1D\nKramers' escape theory framework, which well described nonlinear ionic current,\nand the impact of surface charge density on turning to Ohmic system. Our\nresults possibly provide an alternative view of ionic blockade in Angstrom\nchannels."
    },
    {
        "anchor": "Global isomorphism approach: attractive Yukawa fluid, 2D case: In this paper we apply fluid-lattice gas global isomorphism approach to\nliquid-vapor equilibrium of Yukawa attractive fluid in the two dimensions. The\nconstruction of tangent to the binodal of the fluid in the low-temperature\nregion is performed based on the Zeno-element. The dependence of Zeno-element\nand Boyle parameters on interaction parameters is also studied. It is shown\nthat the asymptotic behavior of the Zeno-element parameters can serve as a\nmarker for liquid phase instability in this case. We also provide the relation\nbetween critical temperatures of bulk (3D) and monolayer (2D) fluid.",
        "positive": "Smoothed particle hydrodynamics study of friction of the coarse-grained\n  $\u03b1$-Al2O3/$\u03b1$-Al2O3 and $\u03b1$-Fe2O3/$\u03b1$-Fe2O3 contacts in\n  behavior of the spring interfacial potential: The paper uses the spring potential to present interaction between the\ncoarse-grained interfacial particles of the $\\alpha$-Al2O3/$\\alpha$-Al2O3 and\n$\\alpha$-Fe2O3/$\\alpha$-Fe2O3 contacts in the sliding friction study of these\nmicron-scale oxides by smoothed particle hydrodynamics simulations. The spring\nconstants of the potential for the particle systems are converted from those of\nthe atomic oxide systems that are yielded by the second order polynomial fits\nof the probed surface potentials in molecular dynamics simulations, and are\ndependent on the particle coarse-graining. It is founded that at micron-scale\nthe friction properties of the oxides are almost independent of the\ncoarse-graining and are the same in the different sliding directions. Even the\nhardness contacts friction coefficient shows a decrease with increasing\nintensity of normal component of the interfacial interaction, originating from\nstability of friction force and growth of normal force. This result is as an\nimplementation for the previous observations of sliding friction of various\nmaterials that showed that a drop of friction coefficient with increasing\nexternally applied normal load has originated from deformation of interfaces or\noccurrence of debris at contact, indicating an unsteady contact."
    },
    {
        "anchor": "Quantum phases of dipolar spinor condensates: We study the zero-temperature ground state structure of a spin-1 condensate\nwith magnetic dipole-dipole interactions. We show that the dipolar interactions\nbreak the rotational symmetry of the Hamiltonian and induce new quantum phases.\nDifferent phases can be reached by tuning the effective strength of the dipolar\ninteractions via modifying the trapping geometry. The experimental feasibility\nof detecting these phases is investigated. The spin-mixing dynamics is also\nstudied.",
        "positive": "Depth dependent dynamics in the hydration shell of a protein: We study the dynamics of hydration water/protein association in folded\nproteins, using lysozyme and myoglobin as examples. Extensive molecular\ndynamics simulations are performed to identify underlying mechanisms of the\ndynamical transition that corresponds to the onset of amplified atomic\nfluctuations in proteins. The number of water molecules within a cutoff\ndistance of each residue scales linearly with protein depth index and is not\naffected by the local dynamics of the backbone. Keeping track of the water\nmolecules within the cutoff sphere, we observe an effective residence time,\nscaling inversely with depth index at physiological temperatures while the\ndiffusive escape is highly reduced below the transition. A depth independent\norientational memory loss is obtained for the average dipole vector of the\nwater molecules within the sphere when the protein is functional. While below\nthe transition temperature, the solvent is in a glassy state, acting as a solid\ncrust around the protein, inhibiting any large scale conformational\nfluctuations. At the transition, most of the hydration shell unfreezes and\nwater molecules collectively make the protein more flexible."
    },
    {
        "anchor": "Dynamic correlations in Brownian many-body systems: For classical Brownian systems driven out of equilibrium we derive\ninhomogeneous two-time correlation functions from functional differentiation of\nthe one-body density and current with respect to external fields. In order to\nallow for appropriate freedom upon building the derivatives, we formally\nsupplement the Smoluchowski dynamics by a source term, which vanishes at the\nphysical solution. These techniques are applied to obtain a complete set of\ndynamic Ornstein-Zernike equations, which serve for the development of\napproximation schemes. The rules of functional calculus lead naturally to\nnon-Markovian equations of motion for the two-time correlators. Memory\nfunctions are identified as functional derivatives of a unique space- and\ntime-nonlocal dissipation power functional.",
        "positive": "Speed inhomogeneity accelerates the information transfer in polar flock: A collection of self-propelled particles (SPPs) shows coherent motion and\nexhibits a true long range ordered (LRO) state in two dimensions. Various\nstudies show that the presence of spatial inhomogeneities can destroy the usual\nlong-range ordering in the system. However, the effects of inhomogeneity due to\nthe intrinsic properties of the particles are barely addressed. In this paper\nwe consider a collection of polar SPPs moving with inhomogeneous speed (IS) on\na two dimensional substrate, which can arise due to varying physical strength\nof the individual particle. To our surprise, the IS not only preserves the\nusual long-range ordering present in the homogeneous speed models but also\ninduces faster ordering in the system. Furthermore, The response of the flock\nto an external perturbation is also faster, compared to Vicsek like model\nsystems, due to the frequent update of neighbors of each SPP in the presence of\nthe IS. Therefore, our study shows that the IS can help in faster information\ntransfer in the moving flock."
    },
    {
        "anchor": "Internal Rotations and Stress Tensor Symmetry in Theories of Nematic\n  Liquids and Solids: The paper analyses kinematics and dynamics of internal rotations with spin\nand their effects on the constitutive relations for uniaxial (nematic) liquids\nand for weakly elastic nematic solids. It is shown that neglecting the internal\nrotational inertia terms and effects of director gradient made the stress\nsymmetric. This not only highly simplifies the theories but also allows\ncalculating all the kinematic variables of internal rotations without any\nadditional constants, other than those presented in the simplified theory with\nsymmetric stress.",
        "positive": "Wave mechanics in an ionic liquid mixture: Experimental measurements of interactions in ionic liquids and concentrated\nelectrolytes over the past decade or so have revealed simultaneous monotonic\nand oscillatory decay modes. These observations have been hard to interpret\nusing classical theories, which typically allow for just one electrostatic\ndecay mode in electrolytes. Meanwhile, substantial progress in the theoretical\ndescription of dielectric response and ion correlations in electrolytes has\nilluminated the deep connection between density and charge correlations and the\nmultiplicity of decay modes characterising a liquid electrolyte. The challenge\nin front of us is to build connections between the theoretical expressions for\npair correlation functions and the directly measured free energy of interaction\nbetween macroscopic surfaces in experiments. Towards this aim, we here present\nmeasurements and analysis of the interactions between macroscopic bodies across\na fluid mixture of two ionic liquids of widely diverging ionic size. The\nmeasured oscillatory interaction forces in the liquid mixtures are\nsignificantly more complex than for either of the pure ionic liquids, but can\nbe fitted to a superposition of two oscillatory and one monotonic mode with\nparameters matching those of the pure liquids. We discuss this empirical\nfinding, which hints at a kind of wave mechanics for interactions in liquid\nmatter."
    },
    {
        "anchor": "Nanoparticle-Protein Interaction: Demystifying the Correlation Between\n  Protein Corona and Aggregation Phenomena: Protein corona formation and nanoparticle aggregation have been heavily\ndiscussed over the last years since the lack of fine-mapping of these two\ncombined effects has hindered the targeted delivery evolution and the\npersonalized nanomedicine development. We present a multi-technique approach\nthat combines Dynamic Light and Small-Angle X-ray Scattering techniques with\ncryo-Transmission Electron Microscopy in a given fashion that efficiently\ndistinguishes protein corona from aggregates formation. This methodology was\ntested using 25-nm model silica nanoparticles incubated with either model\nproteins or biologically relevant proteomes (such as fetal bovine serum and\nhuman plasma) in buffers of low and high ionic strengths to precisely tune\nparticle-to-protein interactions. In this work, we were able to differentiate\nprotein corona, small aggregates formation, and massive aggregation, as well as\nobtain fractal information of the aggregates reliably and straightforwardly.\nThe strategy presented here can be expanded to other particle-to-protein\nmixtures and might be employed as a quality control platform for samples that\nundergo biological tests.",
        "positive": "Magnetic deformation theory of a vesicle: We have extended the Helfrich's spontaneous curvature model [M. Iwamoto and\nZ. C. Ou-Yang. Chem. Phys. Lett. \\textbf{590}(2013)183; Y. X. Deng, et.al.,\nEPL. \\textbf{123}(2018)68002] of the equilibrium vesicle shapes by adding the\ninteraction between magnetic field and the constituent molecules to explain the\nphenomena of the reversibly deformation of artificial stomatocyte[P. G. van\nRhee, et.al., Nat. Commun. \\textbf{Sep 24;5:5010}(2014)doi:\n10.1038/ncomms6010.] and the anharmonic deformation of a self-assembled\nnanocapsules of bola-amphiphilic molecules and the linear birefringence[O.V.\nManyuhina, et.al., Phys. Rev. Lett. \\textbf{98}(2007)146101.]. However, the\nsophistic mathematics in differential geometry is still covered. Here, we\npresent the derivations of formulas in detailed to reveal the perturbation of\ndeformation $\\psi$ under two cases."
    },
    {
        "anchor": "Electrokinetically enhanced cross-stream particle migration in\n  viscoelastic flows: Advancements in understanding the lateral migration of particles have helped\nin enhanced separation in microfluidic devices. In this work, we investigate\nthe effects of electrokinetics on the particle migration in a viscoelastic\nflow, where the electric field is applied parallel to the flow. Through\nexperiments and theoretical analysis, we show that the interaction of\nelectrokinetic and rheological effects can result in an enhancement in the\nmigration by an order of magnitude. The theoretical analysis, in agreement with\nexperiments, demonstrates that the particles can be focused at different\nequilibrium positions based on their intrinsic electrical properties.",
        "positive": "Towards full control of molecular exciton energy transfer via FRET in\n  DNA origami assemblies: Controlling the flow of excitons between organic molecules holds immense\npromise for various applications, including energy conversion, spectroscopy,\nphotocatalysis, sensing, and microscopy. DNA nanotechnology has shown promise\nin achieving this control by using synthetic DNA as a platform for positioning\nand, very recently, for also orienting organic dyes. In this study, the\norientation of doubly-linked dyes in DNA origami structures was manipulated to\ncontrol energy transfer. By controlling independently the orientation of single\ndonor and acceptor molecules, the average energy transfer efficiency was\ndoubled. This work demonstrates the potential of DNA nanotechnology for precise\ncontrol of the excitonic energy transfer with implications for artificial\nlight-harvesting antennas."
    },
    {
        "anchor": "Polymer packaging and ejection in viral capsids: shape matters: We use a mesoscale simulation approach to explore the impact of different\ncapsid geometries on the packaging and ejection dynamics of polymers of\ndifferent flexibility. We find that both packing and ejection times are faster\nfor flexible polymers. For such polymers a sphere packs more quickly and ejects\nmore slowly than an ellipsoid. For semiflexible polymers, however, the case\nrelevant to DNA, a sphere both packs and ejects more easily. We interpret our\nresults by considering both the thermodynamics and the relaxational dynamics of\nthe polymers. The predictions could be tested with bio-mimetic experiments with\nsynthetic polymers inside artificial vesicles. Our results suggest that phages\nmay have evolved to be roughly spherical in shape to optimise the speed of\ngenome ejection, which is the first stage in infection.",
        "positive": "OrthoBoXY: A Simple Way to Compute True Self-Diffusion Coefficients from\n  MD Simulations with Periodic Boundary Conditions Without Prior Knowledge of\n  the Viscosity: Recently, an analytical expression for the system size dependence and\ndirection-dependence of self-diffusion coefficients for neat liquids due to\nhydrodynamic interactions has been derived for molecular dynamics (MD)\nsimulations using orthorhombic unit cells. Based on this description, we show\nthat for systems with a \"magic\" box length ratio of\n$L_z/L_x\\!=\\!L_z/L_y\\!=\\!2.7933596497$ the computed self-diffusion coefficients\n$D_x$ and $D_y$ in $x$- and $y$-direction become system-size independent and\nrepresent the true self-diffusion coefficient $D_0\\!=\\!(D_x+D_y)/2$. Moreover,\nby using this particular box geometry, the viscosity can be determined with a\nreasonable degree of accuracy from the difference of components of the\ndiffusion coefficients in $x$-,$y$- and $z$-direction using the simple\nexpression $\\eta\\!=\\!k_\\mathrm{B}T\\cdot 8.1711245653/[3\\pi\nL_z(D_{x}+D_{y}-2D_z)]$, where $k_\\mathrm{B}$ denotes Boltzmann's constant, and\n$T$ represents the temperature. MD simulations of TIP4P/2005 water for various\nsystem-sizes using both orthorhombic and cubic box geometries are used to test\nthe approach."
    },
    {
        "anchor": "The Dynamics of a Highly Curved Membrane Revealed by All-atom Molecular\n  Dynamics Simulation of a Full-scale Vesicle: In spite of the great success that all-atom molecular dynamics simulations\nhave seen in revealing the nature of the lipid bilayer, the interplay between a\nmembrane's curvature and dynamics remains elusive. This is largely due to the\ncomputational challenges involved in simulating a highly curved membrane, as\nthe one found in a small vesicle. In the present work, thanks to the computing\npower of Anton2, we present the first all-atom molecular dynamics simulation of\na full-scale, realistically composed (both heterogeneous and asymmetric)\nvesicle of a meaningful time scale (over 10 microseconds), which reveals unique\nbiophysical properties of various lipid molecules (diffusion coefficients,\nsurface areas per lipid, order parameters) and packing defects in a highly\ncurved environment. Most interestingly, a bilayer of the same lipid composition\ndemonstrating no phase coexistence when flat shows very strong indictors of\nphase coexistence when highly curved. Lipid molecules found in the\ncurvature-induced different phases are carefully verified by their distinct\ncomposition, area per lipid, parking defects, as well as diffusion coefficient.\nThe result of the all-atom molecular dynamics simulations is consistent with\nprevious experimental and theoretical models and enhance the understanding of\nnanoscale dynamics and membrane organization of small, highly curved\norganelles.",
        "positive": "Topology-dependent anomalous dynamics of ring and linear DNA are\n  sensitive to cytoskeleton crosslinking: Cytoskeletal crowding plays a key role in the diffusion of DNA molecules\nthrough the cell, acting as a barrier to effective intracellular transport and\nconformational stability required for such processes as transfection, viral\ninfection, and gene therapy. Here we elucidate the transport properties and\nconformational dynamics of linear and ring DNA molecules diffusing through\nentangled and crosslinked composite networks of actin and microtubules. We\ncouple single-molecule conformational tracking with differential dynamic\nmicroscopy to reveal that ring and linear DNA exhibit surprisingly distinct\ntransport properties that are influenced differently by cytoskeleton\ncrosslinking. Ring DNA coils are swollen and undergo heterogeneous and biphasic\nsubdiffusion that is hindered by crosslinking. Conversely, crosslinking\nactually facilitates the single-mode subdiffusion that compacted linear chains\nexhibit. Our collective results demonstrate that transient threading by\ncytoskeleton filaments plays a key role in the dynamics of ring DNA, whereas\nthe mobility of the cytoskeleton dictates transport of linear DNA."
    },
    {
        "anchor": "Stable integration of isolated cell membrane patches in a nanomachined\n  aperture: a step towards a novel device for membrane physiology: We investigate the microscopic contact of a cell/semiconductor hybrid. The\nsemiconductor is nanostructured with the aim of single channel recording of ion\nchannels in cell membranes. This approach will overcome many limitations of the\nclassical patch-clamp technique. The integration of silicon-based devices\n'on-chip' promises novel types of experiments on single ion channels.",
        "positive": "Fine structure of Surface Relief Gratings: experiment and a generic\n  stochastic Monte Carlo model of the photoinduced mass transport in\n  azo-polymer: We study experimentally and theoretically a double-peak fine structure of\nSurface Relief Gratings in azo-functionalized poly(etherimide). For the\ntheoretical analysis we develop a stochastic Monte Carlo model for photoinduced\nmass transport in azobenzene functionalized polymer matrix. The long\nsought-after transport of polymer chains from bright to dark places of the\nillumination pattern is demonstrated and characterized, various scenarios for\nthe intertwined processes of build-up of density and SRG gratings are examined.\nModel predicts that for some azo-functionalized materials double-peak SRG\nmaxima can develop in the permanent, quasi-permanent or transient regimes."
    },
    {
        "anchor": "Dynamics of channel incision in a granular bed driven by subsurface\n  water flow: We propose a dynamical model for the erosive growth of a channel in a\ngranular medium driven by subsurface water flow. The model is inferred from\nexperimental data acquired with a laser-aided imaging technique. The evolution\nequation for transverse sections of a channel has the form of a non-locally\ndriven Burgers equation. With fixed coefficients this equation admits an\nasymptotic similarity solution. Ratios of the granular transport coefficients\ncan therefore be extracted from the shape of channels that have evolved in\nsteady driving conditions.",
        "positive": "Electrostatic charging of non-polar colloids by reverse micelles: Colloids dispersed in a non-polar solvent become charged when reverse\nmicelles are added. We study the charge of individual sterically-stabilized\npoly(methyl methacrylate) spheres dispersed in micellar solutions of the\nsurfactants sodium bis(2-ethyl 1-hexyl) sulfosuccinate [AOT], zirconyl 2-ethyl\nhexanoate [Zr(Oct)$_{2}$], and a copolymer of poly(12-hydroxystearic\nacid)--poly(methyl methacrylate) [PHSA-PMMA]. Although the sign of the particle\ncharge is positive for Zr(Oct)$_{2}$, negative for AOT, and essentially neutral\nfor PHSA-PMMA the different micellar systems display a number of common\nfeatures. In particular, we demonstrate that, over a wide range of\nconcentrations, the colloid charge is independent of the number of micelles\nadded and scales linearly with the colloid size. A simple thermodynamic model,\nin which the particle charge is generated by the competitive adsorption of both\npositive and negative micelles, is in good agreement with the experimental\ndata."
    },
    {
        "anchor": "Shaping Nanoscale Ribbons into Micro-Helices of Controllable Radius and\n  Pitch: We report fabrication of highly flexible micron-sized helices from\nnanometer-thick ribbons. Building upon the helical coiling of such ultra-thin\nribbons mediated by surface tension, we demonstrate that the enhanced creep\nproperties of highly confined materials can be leveraged to shape helices into\nthe desired geometry with full control of the final shape. The helical radius,\ntotal length and pitch angle are all freely and independently tunable within a\nwide range: radius within $\\sim$ 1-100 micrometer, length within $\\sim$\n100-3000 micrometer, and pitch angle within $\\sim$ 0-70{\\deg}. This fabrication\nmethod is validated for three different materials: poly(methyl methacrylate),\npoly(dimethylaminoethyl methacrylate), and transition metal chalcogenide\nquantum dots, each corresponding to a different solid-phase structure:\nrespectively a polymer glass, a crosslinked hydrogel, and a nanoparticle array.\nThis demonstrates excellent versatility with respect to material selection,\nenabling further control of the helix mechanical properties.",
        "positive": "Thermal Fluctuations of Singular Bar-Joint Mechanisms: A bar-joint mechanism is a deformable assembly of freely rotating joints\nconnected by stiff bars. Here we develop a formalism to study the equilibration\nof common bar-joint mechanisms with a thermal bath. When the constraints in a\nmechanism cease to be linearly independent, singularities can appear in its\nshape space, which is the part of its configuration space after discarding\nrigid motions. We show that the free-energy landscape of a mechanism at low\ntemperatures is dominated by the neighborhoods of points that correspond to\nthese singularities. We consider two example mechanisms with shape-space\nsingularities and find that they are more likely to be found in configurations\nnear the singularities than others. These findings are expected to help improve\nthe design of nanomechanisms for various applications."
    },
    {
        "anchor": "Role of doped layers in dephasing of 2D electrons in quantum well\n  structures: The temperature and gate voltage dependences of the phase breaking time are\nstudied experimentally in GaAs/InGaAs heterostructures with single quantum\nwell. It is shown that appearance of states at the Fermi energy in the doped\nlayers leads to a significant decrease of the phase breaking time of the\ncarriers in quantum well and to saturation of the phase breaking time at low\ntemperature.",
        "positive": "Elastic Response of Wire Frame Glasses. I. Two Dimensional Model: We study the elastic response of concentrated suspensions of rigid wire frame\nparticles to a step strain. These particles are constructed from infinitely\nthin, rigid rods of length $L$. We specifically compare straight rod-like\nparticles to bent and branched wire frames. In dense suspensions the wire\nframes are frozen in a disordered state by the topological entanglements\nbetween their arms. We present a simple, geometric method to find the scaling\nof the elastic stress with concentration in these glassy systems. We apply this\nmethod to a simple 2D model system where a test particle is placed on a plane\nand constrained by a random distribution of points with number density $\\nu$.\nTwo striking differences between wire frame and rod suspensions are found: 1)\nThe linear elasticity per particle for wire frames is very large, scaling like\n$\\nu^2 L^4$, whereas for rods it much smaller and independent of concentration.\n2) Rods always shear thin but wire frames shear harden for densities less than\n$\\sim \\sqrt{K/k_B T L^4}$, where $K$ is the bending modulus of the particles.\nThe deformation of wire frames is found to be important even for small strains,\nwith the proportion of deformed particles at a particular strain, $\\gamma$,\nbeing given by $(\\nu L^2)^2 \\gamma^2$. Our results agree well with a simple\nsimulation of the 2D system."
    },
    {
        "anchor": "Evidence of growing spatial correlations at the glass transition from\n  nonlinear response experiments: The ac nonlinear dielectric response $\\chi_3(\\omega,T)$ of glycerol was\nmeasured close to its glass transition temperature $T_g$ to investigate the\nprediction that supercooled liquids respond in an increasingly non-linear way\nas the dynamics slows down (as spin-glasses do). We find that\n$\\chi_3(\\omega,T)$ indeed displays several non trivial features. It is peaked\nas a function of the frequency $\\omega$ and obeys scaling as a function of\n$\\omega \\tau(T)$, with $\\tau(T)$ the relaxation time of the liquid. The height\nof the peak, proportional to the number of dynamically correlated molecules\n$N_{corr}(T)$, increases as the system becomes glassy, and $\\chi_3$ decays as a\npower-law of $\\omega$ over several decades beyond the peak. These findings\nconfirm the collective nature of the glassy dynamics and provide the first\ndirect estimate of the $T$ dependence of $N_{corr}$.",
        "positive": "Stress relaxation for granular materials near Jamming under cyclic\n  compression: We have explored isotropically jammed states of semi-2D granular materials\nthrough cyclic compression. In each compression cycle, systems of either\nidentical ellipses or bi-disperse disks, transition between jammed and unjammed\nstates. We determine the evolution of the average pressure, P, and structure\nthrough consecutive jammed states. We observe a transition point, {\\phi}m,\nabove which P persists over many cycles; below {\\phi}m, P relaxes slowly. The\nrelaxation time scale associated with P increases with packing fraction, while\nthe relaxation time scale for collective particle motion remains constant. The\ncollective motion of the ellipses is hindered compared to disks, due to the\nrotational constraints on elliptical particles."
    },
    {
        "anchor": "Optimal Filling of Shapes: We present filling as a type of spatial subdivision problem similar to\ncovering and packing. Filling addresses the optimal placement of overlapping\nobjects lying entirely inside an arbitrary shape so as to cover the most\ninterior volume. In n-dimensional space, if the objects are polydisperse\nn-balls, we show that solutions correspond to sets of maximal n-balls. For\npolygons, we provide a heuristic for finding solutions of maximal discs. We\nconsider the properties of ideal distributions of N discs as N approaches\ninfinity. We note an analogy with energy landscapes.",
        "positive": "Real event detection and the treatment of congestive heart failure: an e\n  fficient technique to help cardiologists to make crucial decisions: Using a method of entropic analysis of time series we establish the\ncorrelation between heartbeat long-range memory and mortality risk in patients\nwith congestive heart failure."
    },
    {
        "anchor": "Nanomechanical Characterization of the Interfacial Properties of\n  Bilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine: We investigate the mechanical properties of bilayers of\n1,2-dipalmitoyl-sn-glycero-3-phosphocholine in the gel phase by using peak\nforce tapping with quantitative nanomechanical mapping. We study both dry and\naqueous bilayers and liposomes supported on the oxidized silicon surface. We\nreport the observation of a marked substrate effect on the measured Young\nmodulus of supported bilayer stacks which decreases as the height of the stack\nincreases. In contrast a clear substrate effect is not observed for the top\nbilayer of supported aqueous liposomes, which is however affected by the\nsurface curvature of the sample. Adhesion forces present quantitative\ndifferences between dry and aqueous samples, with the former being dominated by\ncapillary effects and the latter by non-contact interactions between tip and\nsubstrate. The mechanical properties of stacked bilayers reveal a threshold\nbetween two different regimes, for the lower portion and the upper portion of\nthe stack, that shows a change in the plasticity of the system. The threshold\nis affected by applied setpoint and aging of the sample. We propose that it\narises from the presence of thin layers of hydration water between the\nheadgroups of contacting phospholipid bilayers, which appears to have a major\neffect on the response of the bilayer to an external mechanical stress.",
        "positive": "Superionic liquids in conducting nanoslits: A variety of phase\n  transitions and ensuing charging behavior: We develop a theory of charge storage in ultra-narrow slit-like pores of\nnano\\-structured electrodes. Our analysis is based on the Blume-Capel model in\nexternal field, which we solve analytically on a Bethe lattice. The obtained\nsolutions allow us to explore the complete phase diagram of confined ionic\nliquids in terms of the key parameters characterising the system, such as pore\nionophilicity, interionic interaction energy and voltage. The phase diagram\nincludes the lines of first and second-order, direct and re-entrant, phase\ntransitions, which are manifested by singularities in the corresponding\ncapacitance-voltage plots. To test our predictions experimentally requires\nmono-disperse, conducting, ultra-narrow slit pores, permitting only one layer\nof ions, and thick pore walls, preventing interionic interactions across the\npore walls. However, some qualitative features, which distinguish the behavior\nof ionophilic and ionophobic pores, and its underlying physics, may emerge in\nfuture experimental studies of more complex electrode structures."
    },
    {
        "anchor": "On the coarse-grained density and compressibility of non-ideal crystals:\n  general theory and an application to cluster crystals: The isothermal compressibility of a general crystal is analyzed within\nclassical density functional theory. Our approach can be used for homogeneous\nand unstrained crystals containing an arbitrarily high density of local\ndefects. We start by coarse-graining the microscopic particle density and then\nobtain the long wavelength limits of the correlation functions of elasticity\ntheory and the thermodynamic derivatives. We explicitly show that the long\nwavelength limit of the microscopic density correlation function differs from\nthe isothermal compressibility. It also cannot be obtained from the static\nstructure factor measured in a scattering experiment. We apply our theory to\ncrystals consisting of soft particles which can multiply occupy lattice sites\n('cluster crystals'). The multiple occupancy results in a strong local disorder\nover an extended range of temperatures. We determine the cluster crystals'\nisothermal compressibility, the fluctuations of the lattice occupation numbers\nand their correlation functions, and the dispersion relations. We also discuss\ntheir low-temperature phase diagram.",
        "positive": "On Variational Arguments for Vibrational Modes near Jamming: Amorphous solids tend to present an abundance of soft elastic modes, which\ndiminish their transport properties, generate heterogeneities in their elastic\nresponse, and affect non-linear processes like thermal activation of\nplasticity. This is especially true in packings of particles near their jamming\ntransition, for which effective medium theory and variational arguments can\nboth predict the density of vibrational modes. However, recent numerics support\nthat one hypothesis of the variational argument does not hold. We provide a\nnovel variational argument which overcomes this problem, and correctly predicts\nthe scaling properties of soft modes near the jamming transition. Soft modes\nare shown to be related to the response to a local strain in more connected\nnetworks, and to be characterized by a volume $1/\\delta z$, where $\\delta z$ is\nthe excess coordination above the Maxwell threshold. These predictions are\nverified numerically."
    },
    {
        "anchor": "Dense Regular Packings of Irregular Non-Convex Particles: We present a new numerical scheme to study systems of non-convex, irregular,\nand punctured particles in an efficient manner. We employ this method to\nanalyze regular packings of odd-shaped bodies, not only from a nanoparticle but\nalso both from a computational geometry perspective. Besides determining\nclose-packed structures for many shapes, we also discover a new denser\nconfiguration for Truncated Tetrahedra. Moreover, we consider recently\nsynthesized nanoparticles and colloids, where we focus on the excluded volume\ninteractions, to show the applicability of our method in the investigation of\ntheir crystal structures and phase behavior. Extensions to the presented scheme\ninclude the incorporation of soft particle-particle interactions, the study of\nquasicrystalline systems, and random packings.",
        "positive": "Dynamics of Perfectly Wetting Drops under Gravity: We study the dynamics of small droplets of polydimethylsiloxane (PDMS)\nsilicone oil on a vertical, perfectly-wetting, silicon wafer. Interference\nvideomicroscopy allows us to capture the dynamics of these droplets. We use\ndroplets with a volumes typically ranging from 100 to 500 nanolitres\n(viscosities from 10 to 1000 centistokes) to understand long time derivations\nfrom classical solutions. Past researchers used one dimensional theory to\nunderstand the typical $t^{1/3}$ scaling for the position of the tip of the\ndroplet in time $t$. We observe this regime in experiment for intermediate\ntimes and discover a two-dimensional, similarity solution of the shape of the\ndroplet. However, at long times our droplets start to move more slowly down the\nplane than the $t^{1/3}$ scaling suggests and we observe deviations in droplet\nshape from the similarity solution. We match experimental data with simulations\nto show these deviations are consistent with retarded van der Waals forcing\nwhich should become significant at the small heights observed."
    },
    {
        "anchor": "Minimal cooling speed for glass transition in a simple solvable energy\n  landscape model: The minimal cooling speed required to form a glass is obtained for a simple\nsolvable energy landscape model. The model, made from a two-level system\nmodified to include the topology of the energy landscape, is able to capture\neither a glass transition or a crystallization depending on cooling rate. In\nthis setup, the minimal cooling speed to achieve glass formation is then found\nto be related with the relaxation time and with the thermal history. In\nparticular, we obtain that the thermal history encodes small fluctuations\naround the equilibrium population which are exponentially amplified near the\nglass transition, which mathematically corresponds to the boundary layer of the\nmaster equation. Finally, to verify our analytical results, a kinetic\nMonte-Carlo simulation was implemented.",
        "positive": "Optically enriched and guided dynamics of active skyrmions: Light provides a powerful means of controlling physical behavior of materials\nbut is rarely used to power and guide active matter systems. We demonstrate\noptical control of liquid crystalline topological solitons dubbed \"skyrmions\",\nwhich recently emerged as highly reconfigurable inanimate active particles\ncapable of exhibiting emergent collective behaviors like schooling. Because of\na chiral nematic liquid crystal's natural tendency to twist and its facile\nresponse to electric fields and light, it serves as a testbed for dynamic\ncontrol of skyrmions and other active particles. Using ambient-intensity\nunstructured light, we demonstrate large-scale multifaceted reconfigurations\nand unjamming of collective skyrmion motions powered by oscillating electric\nfields and guided by optically-induced obstacles and patterned illumination."
    },
    {
        "anchor": "Long range ionic and short range hydration effects govern strongly\n  anisotropic clay nanoparticle interactions: The aggregation of clay particles in aqueous solution is a ubiquitous\neveryday process of broad environmental and technological importance. However,\nit is poorly understood at the all-important atomistic level since it depends\non a complex and dynamic interplay of solvent-mediated electrostatic,\nhydrogen-bonding, and dispersion interactions. With this in mind we have\nperformed an extensive set of classical molecular dynamics simulations\n(included enhanced sampling simulations) on the interactions between model\nkaolinite nanoparticles in pure and salty water. Our simulations reveal highly\nanisotropic behaviour in which the interaction between the nanoparticles varies\nfrom attractive to repulsive depending on the relative orientation of the\nnanoparticles. Detailed analysis reveals that at large separation (>1.5 nm)\nthis interaction is dominated by electrostatic effects whereas at smaller\nseparations the nature of the water hydration structure becomes critical. This\nstudy highlights an incredible richness in how clay nanoparticles interact,\nwhich should be accounted for in e.g. coarse grained models of clay\nnanoparticle aggregation.",
        "positive": "Molecular Theory for Self Assembling Mixtures of Patchy Colloids and\n  Colloids with Spherically Symmetric Attractions: The Single Patch Case: In this work we develop the first theory to model self assembling mixtures of\nsingle patch colloids and colloids with spherically symmetric attractions. In\nthe development of the theory we restrict the interactions such that there are\nshort ranged attractions between patchy and spherically symmetric colloids, but\npatchy colloids do not attract patchy colloids and spherically symmetric\ncolloids do not attract spherically symmetric colloids. This results in the\ntemperature, density and composition dependent reversible self assembly of the\nmixture into colloidal star molecules. This type of mixture has been recently\nsynthesized by grafting of complimentary single stranded DNA [Feng et al.,\nAdvanced Materials 25 (20), 2779-2783 (2013)] As a quantitative test of the\ntheory, we perform new monte carlo simulations to study the self assembly of\nthese mixtures; theory and simulation are found to be in excellent agreement."
    },
    {
        "anchor": "Interplay between optical, viscous and elastic forces on an optically\n  trapped Brownian particle immersed in a viscoelastic fluid: We provide a detailed study of the interplay between the different\ninteractions which appear in the Brownian motion of a micronsized sphere\nimmersed in a viscoelastic fluid measured with optical trapping interferometry.\nTo explore a wide range of viscous, elastic and optical forces, we analyze two\ndifferent viscoelastic solutions at various concentrations, which provide a\ndynamic polymeric structure surrounding the Brownian sphere. Our experiments\nshow that, depending of the fluid, optical forces, even if small, slightly\nmodify the complex modulus at low frequencies. Based on our findings, we\npropose an alternative methodology to calibrate this kind of experimental\nset-up when non-Newtonian fluids are used. Understanding the influence of the\noptical potential is essential for a correct interpretation of the mechanical\nproperties obtained by optically-trapped probe-based studies of biomaterials\nand living matter.",
        "positive": "Water permeability in nanopores: when size, shape, and charge matter: Nanoscale materials are a promising desalination technology. While fast water\nflow in nanotubes is well understood, this is not the case for water\npermeability in single-layer membranes. The physical-chemical balance between\nnanopore size, shape, and charge might be the answer."
    },
    {
        "anchor": "Ensemble Inequivalence in Single Molecule Experiments: In bulk systems the calculation of the main thermodynamic quantities leads to\nthe same expectation values in the thermodynamic limit, regardless of the\nchoice of the statistical ensemble. Single linear molecules can be still\nregarded as statistical systems, where the thermodynamic limit is represented\nby infinitely long chains. The question of equivalence between different\nensembles is not at all obvious and has been addressed in the literature, with\nsometimes contradicting conclusions. We address this problem by studying the\nscaling properties of the ensemble difference for two different chain models,\nas a function of the degree of polymerization. By characterizing the scaling\nbehavior of the difference between the isotensional (Gibbs) and isometric\n(Helmholtz) ensembles in the transition from the low-stretching to the\nhigh-stretching regime, we show that ensemble equivalence cannot be reached for\nmacroscopic chains in the low force regime, and we characterize the transition\nfrom the inequivalence to the equivalence regime.",
        "positive": "Charge-regulation effects in nanoparticle self-assembly: Nanoparticles in solution acquire charge through dissociation or association\nof surface groups. Thus, a proper description of their electrostatic\ninteractions requires the use of charge-regulating boundary conditions rather\nthan the commonly employed constant-charge approximation. We implement a hybrid\nMonte Carlo/Molecular Dynamics scheme that dynamically adjusts the charges of\nindividual surface groups of objects while evolving their trajectories.\nCharge-regulation effects are shown to qualitatively change self-assembled\nstructures due to global charge redistribution, stabilizing asymmetric\nconstructs. We delineate under which conditions the conventional\nconstant-charge approximation may be employed and clarify the interplay between\ncharge regulation and dielectric polarization."
    },
    {
        "anchor": "Mean survival times of absorbing triply periodic minimal surfaces: Understanding the transport properties of a porous medium from a knowledge of\nits microstructure is a problem of great interest in the physical, chemical and\nbiological sciences. Using a first-passage time method, we compute the mean\nsurvival time $\\tau$ of a Brownian particle among perfectly absorbing traps for\na wide class of triply-periodic porous media, including minimal surfaces. We\nfind that the porous medium with an interface that is the Schwartz P minimal\nsurface maximizes the mean survival time among this class. This adds to the\ngrowing evidence of the multifunctional optimality of this bicontinuous porous\nmedium. We conjecture that the mean survival time (like the fluid permeability)\nis maximized for triply periodic porous media with a simply connected pore\nspace at porosity $\\phi=1/2$ by the structure that globally optimizes the\nspecific surface. We also compute pore-size statistics of the model\nmicrostructures in order to ascertain the validity of a \"universal curve\" for\nthe mean survival time for these porous media. This represents the first\nnontrivial statistical characterization of triply periodic minimal surfaces.",
        "positive": "Controlled creation of point defects in 3D colloidal crystals: Crystal defects crucially influence the properties of crystalline materials\nand have been extensively studied. Even for the simplest type of defect - the\npoint defect - however, basic properties such as their diffusive behavior, and\ntheir interactions, remain elusive on the atomic scale. Here we demonstrate\nin-situ control over the creation of isolated point defects in a 3D colloidal\ncrystal allowing insight on a single particle level. Our system consists of\nthermoresponsive microgel particles embedded in a crystal of non-responsive\ncolloids. Heating this mixed particle system triggers the shrinking of the\nembedded microgels, which then vacate their lattice positions creating\nvacancy-interstitial pairs. We use temperature-controlled confocal laser\nscanning microscopy to verify and visualize the formation of the point defects.\nIn addition, by re-swelling the microgels we quantify the local lattice\ndistortion around an interstitial defect. Our experimental model system\nprovides a unique opportunity to shed new light on the interplay between point\ndefects, on the mechanisms of their diffusion, on their interactions, and on\ncollective dynamics."
    },
    {
        "anchor": "Shear Induced Demixing in Bidisperse and Polydisperse Polymer Blends:\n  Predictions From a Multi-Fluid Model: In light of recent advancements in the constitutive modelling of bidisperse\nand polydisperse entangled linear polymers, we present a new multi fluid\ngeneralization of the classic two fluid approximation for flows of\ninhomogeneous polymer blends. As an application of the model, we consider\npredictions for the linear and nonlinear dynamics of shear induced demixing\n(SID) instabilities in blends with bidisperse and lognormal molecular weight\ndistributions. We find that even in the absence of any chemical contrast\nbetween component chains, an imposed flow can induce a demixing instability\nprovided there is sufficient contrast in the size of the two chains. The lower\nbound polydispersity for SID coincides with the point where elastic forces (kT\nper entanglement) scaled by the contrast between chains (e.g. polydispersity\nindex minus one) exceed the entropic forces for mixing (kT per chain). For\nbi-disperse blends, we show that the non-linear dynamics of SID strongly\nresemble what has previously been shown for SID in entangled polymer solutions.",
        "positive": "A tutorial on the stability and bifurcation analysis of the\n  electromechanical behaviour of soft materials: Soft materials, such as liquids, polymers, foams, gels, colloids, granular\nmaterials, and most soft biological materials, play an important role in our\ndaily lives. From a mechanical viewpoint, soft materials can easily achieve\nlarge deformations due to their low elastic moduli; meanwhile, surface\ninstabilities, including wrinkles, creases, folds, and ridges, among others,\nare often observed. In particular, soft dielectrics subject to electrical\nstimuli can achieve significantly large deformations that are often accompanied\nby instabilities. While instabilities are often thought to cause failures in\nthe engineering context and carry a negative connotation, they can also be\nharnessed for various applications such as surface patterning, giant actuation\nstrain, and energy harvesting. In the biological world, instability and\nbifurcation phenomena often precede important events such as endocytosis, cell\nfusion, among others. Stability and bifurcation analysis (especially for soft\nmaterials) is challenging and often presents a formidable barrier to entry in\nthis important field. A multidisciplinary audience may lack the background in\none or more areas that are needed to carry out the requisite modeling or even\nunderstand papers in the literature. Furthermore, combining electrostatics\ntogether with large deformations brings its own challenges. In this article, we\nprovide a tutorial on the basics of stability and bifurcation analysis in the\ncontext of soft electromechanical materials. The aim of the article is to use\nsimple examples and ``gently\" lead a reader, unfamiliar with either stability\nanalysis or electrostatics of deformable media, to develop the ability to\nunderstand the pertinent literature that already exists and position them to\nembark on state-of-the-art research on this topic."
    },
    {
        "anchor": "Gravity induced formation of spinners and polar order of spherical\n  microswimmers on a surface: We study numerically the hydrodynamics of a self-propelled particle system,\nconsisting of spherical squirmers sedimented on a flat surface. We observe the\nemergence of dynamic structures, due to the interplay of particle-particle and\nparticle-wall hydrodynamic interactions. At low coverages, our results\ndemonstrate the formation of small chiral spinners: two or three particles are\nbound together via near-field hydrodynamic interactions and form a rotating\ndimer or trimer respectively. The stability of the self-organised spinners can\nbe tuned by the strength of the sedimentation. Increasing the particle\nconcentration leads more interactions between particles and the spinners become\nunstable. At higher area fractions we find that pusher particles can align\ntheir swimming directions leading to a stable polar order and enhanced\nmotility. Further, we test the stability of the polar order in the presence of\na solid boundary. We observe the emergence of a particle vortex in a\ncylindrical confinement.",
        "positive": "Temperature Dependence of Thermodynamic, Dynamical and Dielectric\n  Properties of Water Models: We investigate the temperature dependence of thermodynamic (density, isobaric\nheat capacity), dynamical (self-diffusion coefficient, shear viscosity), and\ndielectric properties of several water models, the commonly employed TIP3P\nwater model, well-established 4-point water model TIP4P-2005, and recently\ndeveloped 4-point water model TIP4P-D. We focus on the temperature range of\ninterest for the field of computational biophysics and soft matter (280-350 K).\nThe 4-point water models lead to a spectacularly improved agreement with\nexperimental data, strongly suggesting that the use of more modern\nparametrizations should be favored compared to the more traditional TIP3P for\nmodeling temperature-dependent phenomena in biomolecular systems."
    },
    {
        "anchor": "Mechanical and microscopic properties of the reversible plastic regime\n  in a 2D jammed material: At the microscopic level, plastic flow of a jammed, disordered material\nconsists of a series of particle rearrangements that cannot be reversed by\nsubsequent deformation. An infinitesimal deformation of the same material has\nno rearrangements. Yet between these limits, there may be a self-organized\nplastic regime with rearrangements, but with no net change upon reversing a\ndeformation. We measure the oscillatory response of a jammed interfacial\nmaterial, and directly observe rearrangements that couple to bulk stress and\ndissipate energy, but do not always give rise to global irreversibility.",
        "positive": "Generation of silicone poly-HIPES with controlled pore sizes via\n  reactive emulsion stabilization: Macrocellular silicone polymers are obtained after solidification of the\ncontinuous phase of a PDMS (polydimethylsiloxane) emulsion, which contains PEG\n(polyethylene glycol) drops of sub-millimetric dimensions. Coalescence of the\nliquid template emulsion is prohibited by a reactive blending approach. We\ninvestigate in detail the relationship between the interfacial properties and\nthe emulsion stability, and we use micro- and millifluidic techniques to\ngeneration macro-cellular polymers with controlled structural properties over a\nwider range of cell-sizes (0.2-2mm) and volume fractions of the continuous\nphase (0.1-40%). This approach could easily be transferred to a wide range of\npolymeric systems."
    },
    {
        "anchor": "Ultrafast viscosity measurement with ballistic optical tweezers: Viscosity is an important property of out-of-equilibrium systems such as\nactive biological materials and driven non-Newtonian fluids, and for fields\nranging from biomaterials to geology, energy technologies and medicine.\nHowever, noninvasive viscosity measurements typically require integration times\nof seconds. Here we demonstrate a four orders-of-magnitude improvement in\nspeed, down to twenty microseconds, with uncertainty dominated by fundamental\nthermal noise for the first time. We achieve this using the instantaneous\nvelocity of a trapped particle in an optical tweezer. To resolve the\ninstantaneous velocity we develop a structured-light detection system that\nallows particle tracking with megahertz bandwidths. Our results translate\nviscosity from a static averaged property, to one that may be dynamically\ntracked on the timescales of active dynamics. This opens a pathway to new\ndiscoveries in out-of-equilibrium systems, from the fast dynamics of phase\ntransitions, to energy dissipation in motor molecule stepping, to violations of\nfluctuation laws of equilibrium thermodynamics.",
        "positive": "Effective mass overshoot in single degree of freedom mechanical systems\n  with a particle damper: We study the response of a single degree of freedom mechanical system\ncomposed of a primary mass, M, a linear spring, a viscous damper and a particle\ndamper. The particle damper consists in a prismatic enclosure of variable\nheight that contains spherical grains (total mass m_p). Contrary to what it has\nbeen discussed in previous experimental and simulation studies, we show that,\nfor small containers, the system does not approach the fully detuned mass limit\nin a monotonous way. Rather, the system increases its effective mass up and\nabove M+m_p before reaching this expected limiting value (which is associated\nwith the immobilization of the particles due to a very restrictive container).\nMoreover, we show that a similar effect appears in the tall container limit\nwhere the system reaches effective masses below the expected asymptotic value\nM. We present a discussion on the origin of these overshoot responses and the\nconsequences for industrial applications."
    },
    {
        "anchor": "Emergent power-law interactions in disordered crystals: We derive exact results for the fluctuations in energy produced by\nmicroscopic disorder in near-crystalline athermal systems. Our formalism\ncaptures the heterogeneity in the elastic energy of polydispersed soft disks in\nenergy-minimized configurations. We use this to predict the distribution of\ninteraction energy between two defects in a disordered background. We show this\ninteraction energy displays an average power-law behaviour $\\langle \\delta E\n\\rangle \\sim \\Delta^{-4}$ at large distances $\\Delta$ between the defects.\nThese interactions upon disorder average also display the sixfold symmetry of\nthe underlying reference crystal. Additionally, we show that the fluctuations\nin the interaction energy encode the athermal correlations introduced by the\ndisordered background. We verify our predictions with energy minimized\nconfigurations of polydispersed soft disks in two dimensions.",
        "positive": "Comparison of structure and transport properties of concentrated hard\n  and soft sphere fluids: Using Newtonian and Brownian dynamics simulations, the structural and\ntransport properties of hard and soft spheres have been studied. The soft\nspheres were modeled using inverse power potentials ($V\\sim r^{-n}$, with $1/n$\nthe potential softness). Although the pressure, diffusion coefficient and\nviscosity depend at constant density on the particle softness up to extremely\nhigh values of $n$, we show that scaling the density with the freezing point\nfor every system effectively collapses these parameters for $n\\geq 18$\n(including hard spheres), for large densities. At the freezing points, the long\nrange structure of all systems is identical, when the distance is measured in\nunits of the interparticle distance, but differences appear at short distances\n(due to the different shape of the interaction potential). This translates into\ndifferences at short times in the velocity and stress autocorrelation\nfunctions, although they concur to give the same value of the corresponding\ntransport coefficient (for the same density to freezing ratio); the microscopic\ndynamics also affects the short time behaviour of the correlation functions and\nabsolute values of the transport coefficients, but the same scaling with the\nfreezing density works for Newtonian or Brownian dynamics. For hard spheres,\nthe short time behaviour of the stress autocorrelation function has been\nstudied in detail, confirming quantitatively the theoretical forms derived for\nit."
    },
    {
        "anchor": "Characterizing Potentials by a Generalized Boltzmann Factor: Based on the concept of a nonequilibrium steady state, we present a novel\nmethod to experimentally determine energy landscapes acting on colloidal\nsystems. By measuring the stationary probability distribution and the current\nin the system, we explore potential landscapes with barriers up to several\nhundred $\\kT$. As an illustration, we use this approach to measure the\neffective diffusion coefficient of a colloidal particle moving in a tilted\npotential.",
        "positive": "Equations of structural relaxation: In the mode coupling theory of the liquid to glass transition the long time\nstructural relaxation follows from equations solely determined by equilibrium\nstructural parameters. The present extension of these structural relaxation\nequations to arbitrarily short times on the one hand allows calculations\nunaffected by model assumptions about the microscopic dynamics and on the other\nhand supplies new starting points for analytical studies. As a first\napplication, power-law like structural relaxation at a glass-transition\nsingularity is explicitly proven for a special schematic MCT model."
    },
    {
        "anchor": "Adsorption Trajectories and Free-Energy Separatrices for Colloidal\n  Particles in Contact with a Liquid-Liquid Interface: We apply the recently developed triangular tessellation technique as\npresented in [J. de Graaf et al., Phys. Rev. E 80, 051405 (2009)] to calculate\nthe free energy associated with the adsorption of anisotropic colloidal\nparticles at a flat interface. From the free-energy landscape, we analyze the\nadsorption process, using a simplified version of Langevin dynamics. The\npresent result is a first step to understand the time-dependent behavior of\ncolloids near interfaces. This study shows a wide range of adsorption\ntrajectories, where the emphasis lies on a strong dependence of the dynamics on\nthe orientation of the colloid at initial contact with the interface. We\nbelieve that the observed orientational dependence in our simple model can be\nrecovered in suitable experimental systems.",
        "positive": "Explicit and asymptotic solutions for frictional incomplete half-plane\n  contacts subject to general oscillatory loading in the steady-state: This contribution presents an asymptotic formulation for the stick-slip\nbehaviour of incomplete contacts under oscillatory variation of normal load,\nmoment, shear load and differential bulk tension. The asymptotic description\nallows us not only to approximate the size of the slip zones during the\nsteady-state of a cyclic problem without knowledge of the geometry or contact\nlaw, but provides a solution when all known analytical solutions for incomplete\ncontacts reach their limitations, that is, in the presence of a varying moment\nand a differential bulk tension large enough to reverse the direction of slip\nat one end of the contact. An insightful comparison between the mathematically\nexplicit analytical solution and the asymptotic approach is drawn using the\nexample geometry of a shallow wedge."
    },
    {
        "anchor": "Beyond Poisson-Boltzmann: fluctuations and fluid structure in a\n  self-consistent theory: Poisson-Boltzmann (PB) theory is the classic approach to soft matter\nelectrostatics which has been applied to numerous problems of physical\nchemistry and biophysics. Its essential limitations are the neglect of\ncorrelation effects and of fluid structure. Recently, several theoretical\ninsights have allowed the formulation of approaches that go beyond PB theory in\na systematic way. In this topical review we provide an update on the\ndevelopments achieved in self-consistent formulations of correlation-corrected\nPoisson-Boltzmann theory. We introduce the corresponding system of coupled\nnonlinear equations for both continuum electrostatics with a uniform dielectric\nconstant and a structured solvent, a dipolar Coulomb fluid, including nonlocal\neffects. While the approach is only approximate and also limited to corrections\nin the so-called weak fluctuation regime, it allows to include physically\nrelevant effects, as we show for a range of applications of these equations.",
        "positive": "Inferring elastic properties of an fcc crystal from displacement\n  correlations: sub-space projection and statistical artifacts: We compute the effective dispersion and vibrational density of states (DOS)\nof two-dimensional sub-regions of three dimensional face centered cubic (FCC)\ncrystals using both a direct projection-inversion technique and a Monte Carlo\nsimulation based on a common underlying Hamiltonian. We study both a (111) and\n(100) plane. We show that for any given direction of wavevector, both (111) and\n(100) show an anomalous $\\omega^2\\sim q$ regime at low $q$ where $\\omega^2$ is\nthe energy associated with the given mode and $q$ is its wavenumber. The\n$\\omega^2\\sim q$ scaling should be expected to give rise to an anomalous DOS,\n$D_\\omega$, at low $\\omega$: $D_\\omega \\sim \\omega^3$ rather than the\nconventional Debye result: $D_\\omega\\sim \\omega^2$. The DOS for (100) looks to\nbe consistent with $D_\\omega \\sim \\omega^3$, while (111) shows something closer\nto the conventional Debye result at the smallest frequencies. In addition to\nthe direct projection-inversion calculation, we perform Monte Carlo simulations\nto study the effects of finite sampling statistics. We show that \\emph{finite\nsampling} artifacts act as an effective disorder and bias $D_\\omega$, giving a\nbehavior closer to $D_\\omega \\sim \\omega^2$ than $D_\\omega \\sim \\omega^3$.\nThese results should have an important impact on the interpretation of recent\nstudies of colloidal solids where the two-point displacement correlations can\nbe obtained directly in real-space via microscopy."
    },
    {
        "anchor": "Long-Range Attraction between Graphene and Water/Oil Interfaces: We directly measured the interactions between a hydrophobic solid and a\nhydrophobic liquid separated by water using force spectroscopy, where colloidal\nprobes were coated with graphene oxide (GO) to interact with immobilized\nheptane droplets in water. We detected attractions with a long range of ~0.5\nmicrons, which cannot be readily explained by standard\nDerjaguin-Landau-Verwey-Overbeek (DLVO) theory. When the GO was reduced to\nbecome more hydrophobic, these forces increased in strength and ranged up to\n1.2 microns, suggesting that the hydrophobic nature of the involved surfaces\ncritically influences the observed long-range forces. Previous studies have\naddressed such hydrophobic attractions, but were limited to solid/water/solid\nand solid/water/air scenarios. Here we expand this knowledge to include the\nsolid/water/liquid situation. Based on our results, we propose air bubbles\nattached to the colloidal probe and molecular rearrangement at the water/oil\ninterface as possible origins of the observed interactions. The proposed\nmechanism expands insights gained from previous to the solid/water/liquid\nsituation and is universally applicable to describe attractive interactions\nbetween hydrophobic bodies of any kind separated by water. Our work will be\nuseful to understand and motivate the formation of many colloid and interface\nphenomena, including emulsions using 2D materials and other\namphiphilic/hydrophobic particles.",
        "positive": "The glass transition of soft colloids: We explore the glassy dynamics of soft colloids using microgels and charged\nparticles interacting by steric and screened Coulomb interactions,\nrespectively. In the supercooled regime, the structural relaxation time\n$\\tau_\\alpha$ of both systems grows steeply with volume fraction, reminiscent\nof the behavior of colloidal hard spheres. Computer simulations confirm that\nthe growth of $\\tau_\\alpha$ on approaching the glass transition is independent\nof particle softness. By contrast, softness becomes relevant at very large\npacking fractions when the system falls out of equilibrium. In this\nnon-equilibrium regime, $\\tau_\\alpha$ depends surprisingly weakly on packing\nfraction and time correlation functions exhibit a compressed exponential decay\nconsistent with stress-driven relaxation. The transition to this novel regime\ncoincides with the onset of an anomalous decrease of local order with\nincreasing density typical of ultrasoft systems. We propose that these peculiar\ndynamics results from the combination of the non-equilibrium aging dynamics\nexpected in the glassy state and the tendency of colloids interacting through\nsoft potentials to refluidize at high packing fractions."
    },
    {
        "anchor": "The Coil-Globule transition in self-avoiding active polymers: We perform numerical simulations of an active fully flexible self-avoiding\npolymer as a function of the quality of the embedding solvent described in\nterms of an effective monomer-monomer interaction. Specifically, by extracting\nthe Flory exponent of the active polymer under different conditions, we are\nable to pin down the location of the coil-globule transition for different\nstrength of the active forces. Remarkably, we find that a simple rescaling of\nthe temperature is capable of qualitatively capture the dependence of the\n$\\Theta$-point of the polymer with the amplitude of the active fluctuations. We\ndiscuss the limits of this mapping, and suggest that a negative active pressure\nbetween the monomers, not unlike the one that has already been found in\nsuspensions of active hard spheres, may also be present in active polymers.",
        "positive": "Controlling auxeticity in curved-beam metamaterials via a deep\n  generative model: Lattice-based mechanical metamaterials are known to exhibit quite a unique\nmechanical behavior owing to their rational internal architecture. This\nincludes unusual properties such as a negative Poisson's ratio, which can be\neasily tuned in reentrant-hexagonal metamaterials by adjusting the angles\nbetween beams. However, changing the angles also affects the overall dimensions\nof the unit cell. We show that by replacing traditional straight beams with\ncurved ones, it is possible to control Poisson's ratio of reentrant-hexagonal\nmetamaterials without affecting their overall dimensions. While the mechanical\nproperties of these structures can be predicted through finite element\nsimulations or, in some cases, analytically, many applications require to\nidentify architectures with specific target properties. To solve this inverse\nproblem, we introduce a deep learning framework for generating metamaterials\nwith desired properties. By supplying the generative model with a guide\nstructure in addition to the target properties, we are not only able to\ngenerate a large number of alternative architectures with the same properties,\nbut also to express preference for a specific shape. Deep learning predictions\ntogether with experimental measurements prove that this approach allows us to\naccurately generate unit cells fitting specific properties for curved-beam\nmetamaterials."
    },
    {
        "anchor": "Computational Rheometry of Yielding and Viscoplastic Flow in\n  Vane-and-Cup Rheometer Fixtures: A planar two-dimensional computational analysis is presented to qualify\ntraditional and fractal vane-in-cup geometries for accurate rheometry of simple\nviscoplastic fluids with and without slip. Numerical simulations based on an\nadaptive augmented Lagrangian scheme are used to study the two-dimensional flow\nfield of yield-stress fluids within and around vane tools with N=3 to 24 arms\nfor a wide range of Bingham numbers, B (i.e. the ratio of the yield stress over\nthe characteristic viscous stress). This allows for accurate calculations of\nthe velocity and stress fields around vanes with various geometries, as well as\ndirect comparison to experimental observations of the output torque measured by\na rheometer, revealing sources of variation and error. We describe the impact\nof the vane structure on the fluid velocity field, from few-arm cruciform vanes\n(N < 6) that significantly perturb the flow away from ideal azimuthal\nkinematics, to many-arm fractal vanes (N > 12) in which the internal structural\nfeatures are successfully ``cloaked\" by a yield surface. This results in the\nshearing of an almost-circular ring of viscoplastic fluid that is\nindistinguishable from the annular ring of fluid deformed around a slip-free\nrotating cylindrical bob and leads to more accurate rheometric measurements of\nthe material flow curve. Moreover, in direct comparison with data from previous\nliterature, we show that slip conditions on the vane surface do not impact the\nvelocity field or measured overall torque T, whereas slip conditions on the\nsmooth outer wall have significant impact on data, even when using a vane\ngeometry. Finally, we describe the impact of vane topography and Bingham\nnumber, B, on the measured torque and rheometric accuracy of vane-in-cup\ngeometries for ``simple\" (inelastic) yield-stress fluids described by either\nthe Bingham plastic or Herschel-Bulkley constitutive model.",
        "positive": "Dynamic magneto-optic coupling in a ferromagnetic nematic liquid crystal: Hydrodynamics of complex fuids with multiple order parameters is governed by\na set of dynamic equations with many material constants, of which only some are\neasily measurable. We present a unique example of a dynamic magneto-optic\ncoupling in a ferromagnetic nematic liquid, in which long-range orientational\norder of liquid crystalline molecules is accompanied by long-range magnetic\norder of magnetic nanoplatelets. We investigate the dynamics of the\nmagneto-optic response experimentally and theoretically and find out that it is\nsignificantly affected by the dissipative dynamic cross-coupling between the\nnematic and magnetic order parameters. The cross-coupling coefficient\ndetermined by fitting the experimental results with a macroscopic theory is of\nthe same order of magnitude as the dissipative coefficient (rotational\nviscosity) that governs the reorientation of pure liquid crystals."
    },
    {
        "anchor": "Free energy of alternating two-component polymer brushes on cylindrical\n  templates: We use computer simulations to investigate the stability of a two-component\npolymer brush de-mixing on a curved template into phases of different\nmorphological properties. It has been previously shown via molecular dynamics\nsimulations that immiscible chains having different length and anchored to a\ncylindrical template will phase separate into striped phases of different\nwidths oriented perpendicularly to the cylindrical axis. We calculate free\nenergy differences for a variety of stripe widths, and extract simple\nrelationships between the sizes of the two polymers, N_1 and N_2, and the free\nenergy dependence on the stripe width. We explain these relationships using\nsimple physical arguments based upon previous theoretical work on the free\nenergy of polymer brushes.",
        "positive": "An improved Monte Carlo method for direct calculation of the density of\n  states: We present an efficient Monte Carlo algorithm for determining the density of\nstates which is based on the statistics of transition probabilities between\nstates. By measuring the infinite temperature transition probabilities--that\nis, the probabilities associated with move proposal only--we are able to\nextract excellent estimates of the density of states. When this estimator is\nused in conjunction with a Wang-Landau sampling scheme [F. Wang and D. P.\nLandau, Phys. Rev. Lett. 86, 2050 (2001)], we quickly achieve uniform sampling\nof macrostates (e.g., energies) and systematically refine the calculated\ndensity of states. This approach requires only potential energy evaluations,\ncontinues to improve the statistical quality of its results as the simulation\ntime is extended, and is applicable to both lattice and continuum systems. We\ntest the algorithm on the Lennard-Jones liquid and demonstrate good statistical\nconvergence properties."
    },
    {
        "anchor": "Influence of random pinning on melting scenario of two-dimensional\n  core-softened potential system: The random disorder can drastically change the melting scenario of\ntwo-dimensional systems and has to be taken into account in the interpretation\nof the experimental results. We present the results of the molecular dynamics\nsimulations of the two dimensional system with the core-softened potentials\nwith two repulsive steps in which a small fraction of the particles is pinned,\ninducing quenched disorder. It is shown that without the quenched disorder the\nsystem with small repulsive shoulder, which is close in the shape to the soft\ndisks, melts in accordance with the melting scenario proposed in Refs.\n[30,31,33] (first-order liquid-hexatic and continuous hexatic-solid\ntransitions). Random pinning widens the hexatic phase, but leaves the melting\nscenario unchanged. For the system with larger repulsive step at high densities\nthe conventional first-order transition takes place without random pinning.\nHowever, in the presence of disorder the single first-order transition\ntransforms into two transitions, one of them (solid-hexatic) is the continuous\nKTHNY-like transition, while the hexatic to isotropic liquid transition occurs\nas the first order transition.",
        "positive": "On the origin of the unusual behavior in the stretching of\n  single-stranded DNA: Force extension curves (FECs), which quantify the response of a variety of\nbiomolecules subject to mechanical force ($f$), are often quantitatively fit\nusing worm-like chain (WLC) or freely-jointed chain (FJC) models. These models\npredict that the chain extension, $x$, normalized by the contour length\nincreases linearly at small $f$ and at high forces scale as $x \\sim (1 -\nf^{-\\alpha})$ where $\\alpha$= 0.5 for WLC and unity for FJC. In contrast,\nexperiments on ssDNA show that over a range of $f$ and ionic concentration, $x$\nscales as $x\\sim\\ln f$, which cannot be explained using WLC or FJC models.\nUsing theory and simulations we show that this unusual behavior in FEC in ssDNA\nis due to sequence-independent polyelectrolyte effects. We show that the $x\\sim\n\\ln f$ arises because in the absence of force the tangent correlation function,\nquantifying chain persistence, decays algebraically on length scales on the\norder of the Debye length. Our theory, which is most appropriate for monovalent\nsalts, quantitatively fits the experimental data and further predicts that such\na regime is not discernible in double stranded DNA."
    },
    {
        "anchor": "Thermodynamic equilibrium of biological macromolecules under mechanical\n  constraints: Equilibrating proteins and other biomacromolecules is cardinal for molecular\ndynamics simulation of such biological systems in which they perform free\ndynamics without any externally-applied mechanical constraint, until\nthermodynamic equilibrium with the surrounding is attained. However, in some\nimportant cases, we have to equilibrate the system of interest in the constant\npresence of certain constraints, being referred to as constrained equilibration\nin the present work. A clear illustration of this type is a single amyloid\n\\b{eta}-strand or RNA, when the reaction coordinate is defined as the distance\nbetween the two ends of the strand and we are interested in carrying out\nreplica-exchange umbrella sampling to map the associated free energy profile as\nthe dependent quantity of interest. In such cases, each sample has to be\nequilibrated with the two ends fixed. Here, we introduced a simulation trick to\nperform this so-called constrained equilibration using steered molecular\ndynamics. We then applied this method to equilibrate a single, stretched\n\\b{eta}-strand of an amyloid beta dodecamer fibril with fixed ends. Examining\nthe associated curves of the total energy and the force exerted on the\npractically-fixed SMD atom over the total timespan broadly supported the\nvalidity of this kind of equilibration.",
        "positive": "Hysteresis and Avalanches in Two Dimensional Foam Rheology Simulations: Foams have unique rheological properties that range from solid-like to\nfluid-like. We study two-dimensional non-coarsening foams of different disorder\nunder shear in a Monte Carlo simulation, using a driven large-Q Potts model. We\nfind that the dynamics of topological rearrangements depend sensitively on the\nstructural disorder."
    },
    {
        "anchor": "Driving dynamic colloidal assembly using eccentric self-propelled\n  colloids: Designing protocols to dynamically direct the self-assembly of colloidal\nparticles has become an important direction in soft matter physics because of\nthe promising applications in fabrication of dynamic responsive functional\nmaterials. Here using computer simulations, we found that in the mixture of\npassive colloids and eccentric self-propelled active particles, when the\neccentricity and self-propulsion of active particles are high enough, the\neccentric active particles can push passive colloids to form a large dense\ndynamic cluster, and the system undergoes a novel dynamic demixing transition.\nOur simulations show that the dynamic demixing occurs when the eccentric active\nparticles move much faster than the passive particles such that the dynamic\ntrajectories of different active particles can overlap with each other while\npassive particles are depleted from the dynamic trajectories of active\nparticles. Our results suggest that this is in analogy to the entropy driven\ndemixing in colloid-polymer mixtures, in which polymer random coils can overlap\nwith each other while deplete the colloids. More interestingly, we find that by\nfixing the passive colloid composition at certain value, with increasing the\ndensity, the system undergoes an intriguing re-entrant mixing, and the demixing\nonly occurs within certain intermediate density range. This suggests a new way\nof designing active matter to drive the self-assembly of passive colloids and\nfabricate dynamic responsive materials.",
        "positive": "On The Existence of Roton Excitations in Bose Einstein Condensates:\n  Signature of Proximity to a Mott Insulating Phase: Within the last decade, artificially engineered Bose Einstein Condensation\nhas been achieved in atomic systems. Bose Einstein Condensates are superfluids\njust like bosonic Helium is and all interacting bosonic fluids are expected to\nbe at low enough temperatures. One difference between the two systems is that\nsuperfluid Helium exhibits roton excitations while Bose Einstein Condensates\nhave never been observed to have such excitations. The reason for the roton\nminimum in Helium is its proximity to a solid phase. The roton minimum is a\nconsequence of enhanced density fluctuations at the reciprocal lattice vector\nof the stillborn solid. Bose Einstein Condensates in atomic traps are not near\na solid phase and therefore do not exhibit roton minimum. We conclude that if\nBose Einstein Condensates in an optical lattice are tuned near a transition to\na Mott insulating phase, a roton minimum will develop at a reciprocal lattice\nvector of the lattice. Equivalently, a peak in the structure factor will appear\nat such a wavevector. The smallness of the roton gap or the largeness of the\nstructure factor peak are experimental signatures of the proximity to the Mott\ntransition."
    },
    {
        "anchor": "Swelling of particle-encapsulating random manifolds: We study the statistical mechanics of a closed random manifold of fixed area\nand fluctuating volume, encapsulating a fixed number of noninteracting\nparticles. Scaling analysis yields a unified description of such swollen\nmanifolds, according to which the mean volume gradually increases with particle\nnumber, following a single scaling law. This is markedly different from the\nswelling under fixed pressure difference, where certain models exhibit\ncriticality. We thereby indicate when the swelling due to encapsulated\nparticles is thermodynamically inequivalent to that caused by fixed pressure.\nThe general predictions are supported by Monte Carlo simulations of two\nparticle-encapsulating model systems -- a two-dimensional self-avoiding ring\nand a three-dimensional self-avoiding fluid vesicle. In the former the\nparticle-induced swelling is thermodynamically equivalent to the\npressure-induced one whereas in the latter it is not.",
        "positive": "Sequential Snapping and Pathways in a Mechanical Metamaterial: Materials which feature bistable elements, hysterons, exhibit memory effects.\nOften these hysterons are difficult to observe or control directly. Here we\nintroduce a mechanical metamaterial in which slender elements, interacting with\npushers, act as mechanical hysterons. We show how we can tune the hysteron\nproperties and pathways under cyclic compression by the geometric design of\nthese elements and how we can tune the pathways of a given sample by tilting\none of the boundaries. Furthermore, we investigate the effect of the coupling\nof a global shear mode to the hysterons, as an example of the interactions\nbetween hysteron and non-hysteron degrees of freedom. We hope our work will\ninspire further studies on designer matter with targeted pathways."
    },
    {
        "anchor": "Undulated cylinders of charged diblock copolymers: We study the cylinder to sphere morphological transition of diblock\ncopolymers in aqueous solution with a hydrophobic block and a charged block. We\nfind a metastable undulated cylinder configuration for a range of charge and\nsalt concentrations which, nevertheless, occurs above the threshold where\nspheres are thermodynamically favorable. By modeling the shape of the cylinder\nends, we find that the free energy barrier for the transition from cylinders to\nspheres is quite large and that this barrier falls significantly in the limit\nof high polymer charge and low solution salinity. This suggests that observed\nundulated cylinder phases are kinetically trapped structures.",
        "positive": "Stoichiometry controls the dynamics of liquid condensates of associative\n  proteins: Multivalent associative proteins with strong complementary interactions play\na crucial role in phase separation of intracellular liquid condensates. We\nstudy the internal dynamics of such \"bond-network\" condensates comprised of two\ncomplementary proteins via scaling analysis and molecular dynamics. We find\nthat when stoichiometry is balanced, relaxation slows down dramatically due to\na scarcity of alternative partners following a bond break. This microscopic\nslow-down strongly affects the bulk diffusivity, viscosity and mixing, which\nprovides a means to experimentally test our predictions."
    },
    {
        "anchor": "Mesophase behaviour of binary mixtures of bent-core and calamitic\n  compounds: The mesophase behaviour of binary mixtures of bent-core and calamitic liquid\ncrystals is presented. The nematogenic 4,6-dichloro-1,3-phenylene\nbis[4'-(10-undecen-1-yloxy)-1,1'-biphenyl-4-carboxylate] (I) was the\nbanana-shaped component. As the calamitic compound ethyl\n4'-(9-decen-1-yloxy)-1,1'-biphenyl-4-carboxylate (II), similar to one arm of\nthe bent-core molecule, was used which exhibits smectic phases in a wide\ntemperature range. A total of 6 mixtures with different compositions were\nprepared and studied by polarising optical microscopy, differential scanning\ncalorimetry and X-ray diffraction on non-oriented samples. In the mixtures a\nnematic phase is not concomitant with smectic A phase, and the temperature\nrange of both phases highly depends on the concentration of the comprising\ncompounds. Lowered melting temperatures have been observed for all mixtures\nwith respect to that of the pure compounds. Unforeseen finding is the induction\nof a monotropic SmC phase in mixtures with lowest concentration of the\nbent-core compound. Semi-empirical quantum-chemical calculations have also been\nperformed. Based on the calculated molecular conformation, as well as on\ncollected X-ray diffraction data, a model for a possible self-assembly of the\nbanana-shaped and calamitic compounds is proposed.",
        "positive": "Dynamics of a rod in a homogeneous/inhomogeneous frozen disordered\n  medium: Correlation functions and non-Gaussian effects: We present molecular dynamics simulations of the motion of a single rigid rod\nin a disordered static 2d-array of disk-like obstacles. Two different\nconfigurations have been used for the latter: A completely random one, and\nwhich thus has an inhomogeneous structure, and an homogeneous ``glassy'' one,\nobtained from freezing a liquid of soft disks in equilibrium. Small differences\nare observed between both structures for the translational dynamics of the rod\ncenter-of-mass. In contrast to this, the rotational dynamics in the glassy host\nmedium is strongly slowed down in comparison with the random one. We calculate\nangular correlation functions for a wide range of rod length $L$ and density of\nobstacles $\\rho$ as control parameters. A two-step decay is observed for large\nvalues of $L$ and $\\rho$, in analogy with supercooled liquids at temperature\nclose to the glass transition. In agreement with the prediction of the Mode\nCoupling Theory, a time-length and time-density scaling is obtained. In order\nto get insight on the relation between the heterogeneity of the dynamics and\nthe structure of the host medium, we determine the deviations from Gaussianity\nat different length scales. Strong deviations are obtained even at spatial\nscales much larger than the rod length. The magnitude of these deviations is\nindependent of the nature of the host medium. This result suggests that the\nlarge scale translational dynamics of the rod is affected only weakly by the\npresence of inhomogeneities in the host medium."
    },
    {
        "anchor": "A Self-Assembled Microlensing Rotational Probe: A technique to measure microscopic rotational motion is presented.\n  When a small fluorescent polystyrene microsphere is attached to a larger\npolystyrene microsphere, the larger sphere acts as a lens for the smaller\nmicrosphere and provides an optical signal that is a strong function of the\nazimuthal angle. We demonstrate the technique by measuring the rotational\ndiffusion constant of the microsphere in solutions of varying viscosity and\ndiscuss the feasibility of using this probe to measure rotational motion of\nbiological systems.",
        "positive": "Soft grain compression: beyond the jamming point: We present the experimental studies of highly strained soft bidisperse\ngranular systems made of hyperelastic and plastic particles. We explore the\nbehavior of granular matter deep in the jammed state from local field\nmeasurement from the grain scale to the global scale. By mean of digital image\ncorrelation and accurate image recording we measure for each compression step\nthe evolution of the particle geometries and their right Cauchy-Green strain\ntensor fields. We analyze the evolution of the usual macroscopic observables\n(stress, packing fraction, coordination, fraction of non-rattlers,\n\\textit{etc}.) along the compression process through the jamming point and far\nbeyond. We also analyze the evolution of the local strain statistics and\nevidence a crossover in the material behavior deep in the jammed state. We show\nthat this crossover depends on the particle material. We argue that the strain\nfield is a reliable observable to describe the evolution of a granular system\nthrough the jamming transition and deep in the dense packing state whatever is\nthe material behavior."
    },
    {
        "anchor": "Trapped-particle microrheology of active suspensions: In microrheology, the local rheological properties such as viscoelasticity of\na complex fluid are inferred from the free or forced motion of embedded\ncolloidal probe particles. Theoretical machinery developed for forced-probe\nmicrorheology of colloidal suspensions focused on either constant-force (CF) or\nconstant-velocity (CV) probes while in experiments neither the force nor the\nkinematics of the probe is fixed. More importantly, the constraint of CF or CV\nintroduces a difficulty in the meaningful quantification of the fluctuations of\nthe probe due to a thermodynamic uncertainty relation. It is known that for a\nBrownian particle trapped in a harmonic potential well, the product of the\nstandard deviations of the trap force and the particle position is $d k_BT$ in\n$d$ dimensions with $k_BT$ being the thermal energy. As a result, if the force\n(position) is not allowed to fluctuate, the position (force) fluctuation\nbecomes infinite. To allow the measurement of fluctuations, in this work we\nconsider a microrheology model in which the embedded probe is dragged along by\na moving harmonic potential so that both its position and the trap force are\nallowed to fluctuate. Starting from the full Smoluchowski equation governing\nthe dynamics of $N$ hard active Brownian particles, we derive a pair\nSmoluchowski equation describing the dynamics of the probe as it interacts with\none bath particle by neglecting hydrodynamic interactions among particles in\nthe dilute limit. From this, we determine the mean and the variance (i.e.,\nfluctuation) of the probe position in terms of the pair probability\ndistribution. We then characterize the behavior of the system in the limits of\nboth weak and strong trap. By taking appropriate limits, we show that our\ngeneralized model can be reduced to the well-studied CF or CV microrheology\nmodels.",
        "positive": "Microscopic dynamics and failure precursors of a gel under mechanical\n  load: Material failure is ubiquitous, with implications from geology to everyday\nlife and material science. It often involves sudden, unpredictable events, with\nlittle or no macroscopically detectable precursors. A deeper understanding of\nthe microscopic mechanisms eventually leading to failure is clearly required,\nbut experiments remain scarce. Here, we show that the microscopic dynamics of a\ncolloidal gel, a model network-forming system, exhibit dramatic changes that\nprecede its macroscopic failure by thousands of seconds. Using an original\nsetup coupling light scattering and rheology, we simultaneously measure the\nmacroscopic deformation and the microscopic dynamics of the gel, while applying\na constant shear stress. We show that the network failure is preceded by\nqualitative and quantitative changes of the dynamics, from reversible particle\ndisplacements to a burst of irreversible plastic rearrangements."
    },
    {
        "anchor": "Self-consistent variational theory for globules: A self-consistent variational theory for globules based on the uniform\nexpansion method is presented. This method, first introduced by Edwards and\nSingh to estimate the size of a self-avoiding chain, is restricted to a good\nsolvent regime, where two-body repulsion leads to chain swelling. We extend the\nvariational method to a poor solvent regime where the balance between the\ntwo-body attractive and the three-body repulsive interactions leads to\ncontraction of the chain to form a globule. By employing the Ginzburg\ncriterion, we recover the correct scaling for the $\\theta$-temperature. The\nintroduction of the three-body interaction term in the variational scheme\nrecovers the correct scaling for the two important length scales in the globule\n- its overall size $R$, and the thermal blob size $\\xi_{T}$. Since these two\nlength scales follow very different statistics - Gaussian on length scales\n$\\xi_{T}$, and space filling on length scale $R$ - our approach extends the\nvalidity of the uniform expansion method to non-uniform contraction rendering\nit applicable to polymeric systems with attractive interactions. We present one\nsuch application by studying the Rayleigh instability of polyelectrolyte\nglobules in poor solvents. At a critical fraction of charged monomers, $f_c$,\nalong the chain backbone, we observe a clear indication of a first-order\ntransition from a globular state at small $f$, to a stretched state at large\n$f$; in the intermediate regime the bistable equilibrium between these two\nstates shows the existence of a pearl-necklace structure.",
        "positive": "Accurate determination of elastic parameters for multi-component\n  membranes: Heterogeneities in the cell membrane due to coexisting lipid phases have been\nconjectured to play a major functional role in cell signaling and membrane\ntrafficking. Thereby the material properties of multiphase systems, such as the\nline tension and the bending moduli, are crucially involved in the kinetics and\nthe asymptotic behavior of phase separation. In this Letter we present a\ncombined analytical and experimental approach to determine the properties of\nphase-separated vesicle systems. First we develop an analytical model for the\nvesicle shape of weakly budded biphasic vesicles. Subsequently experimental\ndata on vesicle shape and membrane fluctuations are taken and compared to the\nmodel. The combined approach allows for a reproducible and reliable\ndetermination of the physical parameters of complex vesicle systems. The\nparameters obtained set limits for the size and stability of nanodomains in the\nplasma membrane of living cells."
    },
    {
        "anchor": "Hydrodynamic Flows on Curved Surfaces: Spectral Numerical Methods for\n  Radial Manifold Shapes: We formulate hydrodynamic equations and spectrally accurate numerical methods\nfor investigating the role of geometry in flows within two-dimensional fluid\ninterfaces. To achieve numerical approximations having high precision and level\nof symmetry for radial manifold shapes, we develop spectral Galerkin methods\nbased on hyperinterpolation with Lebedev quadratures for $L^2$-projection to\nspherical harmonics. We demonstrate our methods by investigating hydrodynamic\nresponses as the surface geometry is varied. Relative to the case of a sphere,\nwe find significant changes can occur in the observed hydrodynamic flow\nresponses as exhibited by quantitative and topological transitions in the\nstructure of the flow. We present numerical results based on the\nRayleigh-Dissipation principle to gain further insights into these flow\nresponses. We investigate the roles played by the geometry especially\nconcerning the positive and negative Gaussian curvature of the interface. We\nprovide general approaches for taking geometric effects into account for\ninvestigations of hydrodynamic phenomena within curved fluid interfaces.",
        "positive": "Spinning elastic beads: a route for simultaneous measurements of shear\n  modulus and interfacial energy of soft materials: Large deformations of soft elastic beads spinning at high angular velocity in\na denser background fluid are investigated theoretically, numerically, and\nexperimentally using millimeter-size polyacrylamide hydrogel particles\nintroduced in a spinning drop tensiometer. We determine the equilibrium shapes\nof the beads from the competition between the centrifugal force and the\nrestoring elastic and surface forces. Considering the beads as neo-Hookean up\nto large deformations, we show that their elastic modulus and surface energy\nconstant can be simultaneously deduced from their equilibrium shape. Also, our\nresults provide further support to the scenario in which surface energy and\nsurface tension coincide for amorphous polymer gels."
    },
    {
        "anchor": "Multiple timescale contact charging: Contact charging between insulators is one of the most basic, yet least well\nunderstood, of physical processes. For example we have no clear theory for how\ninsulators recruit enough charge carriers to deposit charge but not enough to\ndischarge. In this letter we note that charging and discharging kinetics may be\ndistinct, and from this observation we develop a mathematical model. The model\nsurprisingly predicts that charging can decrease as contact frequency\nincreases: we confirm this prediction experimentally and propose future steps.",
        "positive": "Phase Transition Dynamics and Stochastic Resonance in Topologically\n  Confined Nematic Liquid Crystals: Topological defects resulted from boundary constraints in confined liquid\ncrystals have attracted extensive research interests. In this paper, we use\nnumerical simulation to study the phase transition dynamics in the context of\nstochastic resonance in a bistable liquid crystal device containing defects.\nThis device is made of nematic liquid crystals confined in a shallow square\nwell, and is described by the planar Lebwohl-Lasher model. The stochastic phase\ntransition processes of the system in the presence of a weak oscillating\npotential is simulated using an over-damped Langevin dynamics. Our simulation\nresults reveal that, depending on system size, the phase transition may follow\ntwo distinct pathways: in small systems the pre-existing defect structures at\nthe corners hold until the last stage and there is no newly formed defect point\nin the bulk during the phase transition, In large systems new defect points\nappear spontaneously in the bulk and eventually merge with the pre-existing\ndefects at the corners. For both transition pathways stochastic resonance can\nbe observed, but show dramatic difference in their responses to the boundary\nanchoring strength. In small systems we observe a \"sticky-boundary\" effect for\na certain range of anchoring strength in which the phase transition gets stuck\nand stochastic resonance becomes de-activated. Our work demonstrates the\ndynamical interplay among defects, noises, and boundary conditions in confined\nliquid crystals."
    },
    {
        "anchor": "Vibrations of Sessile Drops of Soft Hydrogels: Sessile drops of soft hydrogels were vibrated vertically by subjecting them\nto a mechanically induced Gaussian white noise. Power spectra of the surface\nfluctuation of the gel allowed identification of its resonant frequency that\ndecreases with their mass, but increases with its shear modulus. The principal\nresonant frequencies of the spheroidal modes of the gel of shear moduli ranging\nfrom 55 Pa to 290 Pa were closest to the lowest Rayleigh mode of vibration of a\ndrop of pure water. These observations coupled with the fact that the resonance\nfrequency varies inversely as the square root of the mass in all cases suggest\nthat they primarily correspond to the capillary (or a pseudo-capillary) mode of\ndrop vibration. The contact angles of the gel drops also increase with the\nmodulus of the gel. When the resonance frequencies are corrected for the\nwetting angles, and plotted against the fundamental frequency scale\n(gamma/mu)^0.5, all the data collapse nicely on a single plot provided that the\nlatter is shifted by a shear modulus dependent factor (1+mu.L/gamma). A length\nscale L, independent of both the modulus and the mass of the drop emerges from\nsuch a fit.",
        "positive": "Possible Universal Relation Between Short time $\u03b2$-relaxation and\n  Long time $\u03b1$-relaxation in Glass-forming Liquids: Relaxation processes in supercooled liquids are known to exhibit interesting\nas well as complex behavior. One of the hallmarks of this relaxation process\nobserved in the measured auto correlation function is occurrence of multiple\nsteps of relaxation. The shorter time relaxation is known as the\n$\\beta$-relaxation which is believed to be due to the motion of particles in\nthe cage formed by their neighbors. One the other hand longer time relaxation,\nthe $\\alpha$-relaxation is believed to be the main relaxation process in the\nliquids. The timescales of these two relaxations processes dramatically\nseparate out with supercooling. In spite of decades of researches, it is still\nnot clearly known how these relaxation processes are related to each other. In\nthis work we show that, there is a possible universal relation between short\ntime $\\beta$-relaxation and the long time $\\alpha$-relaxation. This relation is\nfound to be quite robust across many different model systems. Finally we show\nthat length scale obtained from the finite size scaling analysis of $\\beta$\ntimescale is same as that of length scale associated with the dynamic\nheterogeneity in both two and three dimensions."
    },
    {
        "anchor": "Interface stabilization in adhesion caused by elastohydrodynamic\n  deformation: Interfacial instabilities are common phenomena observed during adhesion\nmeasurements involving viscoelastic polymers or fluids. Typical probe-tack\nadhesion measurements with soft adhesives are conducted with rigid probes.\nHowever, in many settings, such as for medical applications, adhesives make and\nbreak contact from soft surfaces such as skin. Here we study how detachment\nfrom soft probes alters the debonding mechanism of a model viscoelastic polymer\nfilm. We demonstrate that detachment from a soft probe suppresses\nSaffman-Taylor instabilities commonly encountered in adhesion. We suggest the\nmechanism for interface stabilization is elastohydrodynamic deformation of the\nprobe and propose a scaling for the onset of stabilization.",
        "positive": "Viscoelasticity of reversibly crosslinked networks of semiflexible\n  polymers: We present a theoretical framework for the linear and nonlinear visco-elastic\nproperties of reversibly crosslinked networks of semiflexible polymers. In\ncontrast to affine models where network strain couples to the polymer\nend-to-end distance, in our model strain rather serves to locally distort the\nnetwork structure. This induces bending modes in the polymer filaments, the\nproperties of wich are slaved to the surrounding network structure.\nSpecifically, we investigate the frequency-dependent linear rheology, in\nparticular in combination with crosslink binding/unbinding processes. We also\ndevelop schematic extensions to describe the nonlinear response during creep\nmeasurements as well as during constant-strainrate ramps."
    },
    {
        "anchor": "Contact area of rough spheres: Large scale simulations and simple\n  scaling laws: We use molecular simulations to study the nonadhesive and adhesive\natomic-scale contact of rough spheres with radii ranging from nanometers to\nmicrometers over more than ten orders of magnitude in applied normal load. At\nthe lowest loads, the interfacial mechanics is governed by the contact\nmechanics of the first asperity that touches. The dependence of contact area on\nnormal force becomes linear at intermediate loads and crosses over to Hertzian\nat the largest loads. By combining theories for the limiting cases of nominally\nflat rough surfaces and smooth spheres, we provide parameter-free analytical\nexpressions for contact area over the whole range of loads. Our results\nestablish a range of validity for common approximations that neglect curvature\nor roughness in modeling objects on scales from atomic force microscope tips to\nball bearings.",
        "positive": "Discrepancies in dynamic yield stress measurements of cement pastes: The dynamic yield stress associated with the flow cessation of cement pastes\nis measured using a rheometer equipped with various shear geometries such as\nvane, helical, sandblasted co-axial cylinders, and serrated parallel plates, as\nwell as with the mini-cone spread test. Discrepancies in yield stress values\nare observed for cement pastes at various volume fractions, with one to two\norders of magnitude difference between vane, helical and mini-cone spread\nmeasurements on the one hand, and co-axial cylinder and parallel plate\nmeasurements on the other hand. To understand this discrepancy, the flow\nprofile of a cement paste in the parallel-plate geometry is investigated with a\nhigh-speed camera, revealing the rapid formation of an un-sheared band near the\nstatic bottom plate. The width of this band depends upon the rotational\nvelocity of the top plate, and upon the shear time. Recalculation of shear\nstress shows that the reduced sheared gap alone cannot explain the low measured\nyield stress. Further exploration suggests the formation of zones with lower\nparticle content, possibly linked to cement particle sedimentation. Here, we\nargue that the complex nature of cement pastes, composed of negatively buoyant\nnon-Brownian particles with attractive interactions due to highly charged\nnano-size hydration products, accounts for their complex rheological behavior."
    },
    {
        "anchor": "Quantitative Morphological Optimization of Bicontinuous Pickering\n  Emulsions via Interfacial Curvatures: Bicontinuous Pickering emulsions (bijels) are a physically interesting class\nof soft materials with many potential applications including catalysis,\nmicrofluidics and tissue engineering. They are created by arresting the\nspinodal decomposition of a partially-miscible liquid with a (jammed) layer of\ninterfacial colloids. Porosity $L$ (average interfacial separation) of the\nbijel is controlled by varying the radius ($r$) and volume fraction ($\\phi$) of\nthe colloids ($L \\propto r/\\phi$). However, to optimize the bijel structure\nwith respect to other parameters, e.g. quench rate, characterizing by $L$ alone\nis insufficient. Hence, we have used confocal microscopy and X-ray CT to\ncharacterize a range of bijels in terms of local and area-averaged interfacial\ncurvatures. In addition, the curvatures of bijels have been monitored as a\nfunction of time, which has revealed an intriguing evolution up to 60 minutes\nafter bijel formation, contrary to previous understanding.",
        "positive": "Dynamics of certain Euler-Bernoulli rods and rings from a minimal\n  coupling quantum isomorphism: In some parameter and solution regimes, a minimally coupled nonrelativistic\nquantum particle in 1d is isomorphic to a much heavier, vibrating, very thin\nEuler-Bernoulli rod in 3d, with ratio of bending modulus to linear density\n$(\\hbar/2m)^2$. For $m=m_e$, this quantity is comparable to that of a\nmicrotubule. Axial forces and torques applied to the rod play the role of\nscalar and vector potentials, respectively, and rod inextensibility plays the\nrole of normalization. We show how an uncertainty principle $\\Delta x\\Delta\np_x\\gtrsim\\hbar$ governs transverse deformations propagating down the\ninextensible, force and torque-free rod, and how orbital angular momentum\nquantized in units of $\\hbar$ or $\\hbar/2$ (depending on calculation method)\nemerges when the force and torque-free inextensible rod is formed into a ring.\nFor torqued rings with large wavenumbers, a ``twist quantum'' appears that is\nsomewhat analogous to the magnetic flux quantum. These and other results are\nobtained from a purely classical treatment of the rod, i.e., without quantizing\nany classical fields."
    },
    {
        "anchor": "Fluorescence correlation spectroscopy in thin films at reflecting\n  substrates as a means to study nanoscale structure and dynamics at\n  soft-matter interfaces: Structure and dynamics at soft-matter interfaces play an important role in\nnature and technical applications. Optical single-molecule investigations are\nnon-invasive and capable to reveal heterogeneities at the nanoscale. In this\nwork we develop an autocorrelation function (ACF) approach to retrieve tracer\ndiffusion parameters obtained from fluorescence correlation spectroscopy (FCS)\nexperiments in thin liquid films at reflecting substrates. This approach then\nis used to investigate structure and dynamics in 100 nm thick 8CB liquid\ncrystal films on silicon wafers with five different oxide thicknesses. We find\na different extension of the structural reorientation of 8CB at the\nsolid-liquid interface for thin and for thick oxide. For the thin oxides, the\nperylenediimide tracer diffusion dynamics in general agrees with the\nhydrodynamic modeling using no-slip boundary conditions with only a small\ndeviation close to the substrate, while a considerably stronger decrease of the\ninterfacial tracer diffusion is found for the thick oxides.",
        "positive": "Capillary Thinning of Elastic and Viscoelastic Threads: from\n  Elastocapillarity to Phase Separation: The formation and destabilisation of viscoelastic filaments are of importance\nin many industrial and biological processes. Filament instabilities have been\nobserved for viscoelastic fluids but recently also for soft elastic solids. In\nthis work, we address the central question how to connect the dynamical\nbehavior of viscoelastic liquids to that of soft elastic solids. We take\nadvantage of a biopolymer material whose viscoelastic properties can be tuned\nover a very large range by its pH, and study the destabilization and ensuing\ninstabilities in uniaxial extensional deformation. In agreement with very\nrecent theory, we find that the interface shapes dictated by the instabilities\nconverge to an identical similarity solution for low-viscosity viscoelastic\nfluids and highly elastic gels. We thereby bridge the gap between very fluid\nand strongly elastic materials. In addition, we provide direct evidence that at\nlate times an additional filament instability occurs due to a dynamical phase\nseparation."
    },
    {
        "anchor": "Diffusion of chiral active particles in a Poiseuille flow: We study the diffusive behavior of chiral active (self-propelled) Brownian\nparticles in a two-dimensional microchannel with a Poiseuille flow. Using\nnumerical simulations, we show that the behavior of the transport coefficients\nof particles, for example, the average velocity $v$ and the effective diffusion\ncoefficient $D_{eff}$, strongly depends on flow strength $u_0$, translational\ndiffusion constant $D_0$, rotational diffusion rate $D_\\theta$, and chirality\nof the active particles $\\Omega$. It is demonstrated that the particles can\nexhibit upstream drift, resulting in a negative $v$, for the optimal parameter\nvalues of $u_0$, $D_\\theta$, and $\\Omega$. Interestingly, the direction of $v$\ncan be controlled by tuning these parameters. We observe that for some optimal\nvalues of $u_0$ and $\\Omega$, the chiral particles aggregate near a channel\nwall, and the corresponding $D_{eff}$ is enhanced. However, for the nonchiral\nparticles ($\\Omega = 0$), the $D_{eff}$ is suppressed by the presence of\nPoiseuille flow. It is expected that these findings have a great potential for\ndeveloping microfluidic and lab-on-a-chip devices for separating the active\nparticles.",
        "positive": "A Modified Smoothed Particle Hydrodynamics Approach for Modelling\n  Dynamic Contact Angle Hysteresis: Dynamic wetting plays an important role in the physics of multiphase flow,\nand has significant influence on many industrial and geotechnical applications.\nIn this work, a modified smoothed particle hydrodynamics (SPH) model is\nemployed to simulate surface tension, contact angle, and dynamic wetting\neffects. The wetting and dewetting phenomena are simulated in a capillary tube,\nwhere the liquid particles are raised or withdrawn by a shifting substrate. The\nSPH model is modified by introducing a newly-developed viscous force\nformulation at liquid-solid interface to reproduce the rate-dependent behaviour\nof moving contact line. Dynamic contact angle simulations with interfacial\nviscous force are conducted to verify the effectiveness and accuracy of this\nnew formulation. In addition, the influence of interfacial viscous force with\ndifferent magnitude on contact angle dynamics is examined by empirical power\nlaw correlations, and the derived constants suggest the dynamic contact angle\nchanges monotonically with interfacial viscous force. The simulation results\nare consistent with the experimental observations and theoretical predictions,\nimplying that the interfacial viscous force can be associated with slip length\nof flow and microscopic surface roughness. This work has demonstrated that the\nmodified SPH model can successfully account for the rate-dependent effects of\nmoving contact line, and can be used for realistic multiphase flow simulation\nunder dynamic conditions."
    },
    {
        "anchor": "From short-range repulsion to Hele-Shaw problem in a model of tumor\n  growth: We investigate the large time behavior of an agent based model describing\ntumor growth. The microscopic model combines short-range repulsion and cell\ndivision. As the number of cells increases exponentially in time, the\nmicroscopic model is challenging in terms of computational time. To overcome\nthis problem, we aim at deriving the associated macroscopic dynamics leading\nhere to a porous media type equation. As we are interested in the long time\nbehavior of the dynamics, the macroscopic equation obtained through usual\nderivation method fails at providing the correct qualitative behavior (e.g.\nstationary states differ from the microscopic dynamics). We propose a modified\nversion of the macroscopic equation introducing a density threshold for the\nrepulsion. We numerically validate the new formulation by comparing the\nsolutions of the micro- and macro- dynamics. Moreover, we study the asymptotic\nbehavior of the dynamics as the repulsion between cells becomes singular\n(leading to non-overlapping constraints in the microscopic model). We manage to\nshow formally that such an asymptotic limit leads to a Hele-Shaw type problem\nfor the macroscopic dynamics.\n  The macroscopic model derived in this paper therefore enables to overcome the\nproblem of large computational time raised by the microscopic model and stays\nclosely linked to the microscopic dynamics.",
        "positive": "Vesicle deformations by clusters of transmembrane proteins: We carry out a coarse-grained molecular dynamics simulation of phospholipid\nvesicles with transmembrane proteins. We measure the mean and Gaussian\ncurvatures of our protein-embedded vesicles and quantitatively show how protein\nclusters change the shapes of their host vesicles. The effects of depletion\nforce and vesiculation on protein clustering are also investigated. By\nincreasing the protein concentration, clusters are fragmented to smaller\nbundles, which are then redistributed to form more symmetric structures\ncorresponding to lower bending energies. Big clusters and highly aspherical\nvesicles cannot be formed when the fraction of protein to lipid molecules is\nlarge."
    },
    {
        "anchor": "Thermally driven order-disorder transition in two-dimensional soft\n  cellular systems: Many systems, including biological tissues and foams, are made of highly\npacked units having high deformability but low compressibility. At two\ndimensions, these systems offer natural tesselations of plane with fixed\ndensity, in which transitions from ordered to disordered patterns are often\nobserved, in both directions. Using a modified Cellular Potts Model algorithm\nthat allows rapid thermalization of extensive systems, we numerically explore\nthe order-disorder transition of monodisperse, two-dimensional cellular systems\ndriven by thermal agitation. We show that the transition follows most of the\npredictions of Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory\ndeveloped for melting of 2D solids, extending the validity of this theory to\nsystems with many-body interactions. In particular, we show the existence of an\nintermediate hexatic phase, which preserves the orientational order of the\nregular hexagonal tiling, but looses its positional order. In addition to\nshedding light on the structural changes observed in experimental systems, our\nstudy shows that soft cellular systems offer macroscopic systems in which KTHNY\nmelting scenario can be explored, in the continuation of Bragg's experiments on\nbubble rafts.",
        "positive": "Influence of Roughness on Granular Avalanches: Combining X-ray tomography with simultaneous shear force measurement, we\ninvestigate shear-induced granular avalanches using spherical particles with\ndifferent surface roughness. We find that systems consisting of particles with\nlarge surface roughness display quasi-periodic avalanches interrupted by\ncrackling-like small ones. In contrast, systems consisting of particles with\nsmall roughness display no detectable avalanches. The stress drop of\nquasi-periodic avalanche shows a linear relation with the correlation length of\nparticle non-affine displacement, suggesting that roughness enhances\ninter-particle locking and hence particle-level dynamic correlation length.\nHowever, the nonaffine displacement is two orders of magnitude smaller than\nparticle size, indicating that stress is mainly released on the length scale of\nroughness. The correlation length of non-affine displacements abruptly\nincreases when a quasi-periodic avalanche occurs, suggesting that\nquasi-periodic avalanches can be interpreted as a spinodal nucleation event in\na first-order phase transition."
    },
    {
        "anchor": "Rationalizing Euclidean Assemblies of Hard Polyhedra from Tessellations\n  in Curved Space: Entropic self-assembly is governed by the shape of the constituent particles,\nyet a priori prediction of crystal structures from particle shape alone is\nnon-trivial for anything but the simplest of space-filling shapes. At the same\ntime, most polyhedra are not space-filling due to geometric constraints, but\nthese constraints can be relaxed or even eliminated by sufficiently curving\nspace. We show using Monte Carlo simulations that the majority of hard Platonic\nshapes self-assemble entropically into space-filling crystals when constrained\nto the surface volume of a 3-sphere. As we gradually decrease curvature to\n\"flatten\" space and compare the local morphologies of crystals assembling in\ncurved and flat space, we show that the Euclidean assemblies can be categorized\neither as remnants of tessellations in curved space (tetrahedra and\ndodecahedra) or non-tessellation-based assemblies caused by large-scale\ngeometric frustration (octahedra and icosahedra).",
        "positive": "Inferring the diameter of a biopolymer from its stretching response: We investigate the stretching response of a thick polymer model by means of\nextensive stochastic simulations. The computational results are synthesized in\nan analytic expression that characterizes how the force versus elongation curve\ndepends on the polymer structural parameters: its thickness and granularity\n(spacing of the monomers). The expression is used to analyze experimental data\nfor the stretching of various different types of biopolymers: polypeptides,\npolysaccharides and nucleic acids. Besides recovering elastic parameters (such\nas the persistence length) that are consistent with those obtained from\nstandard entropic models, the approach allows to extract viable estimates for\nthe polymers diameter and granularity. This shows that the basic structural\npolymer features have such a profound impact on the elastic behaviour that they\ncan be recovered with the sole input of stretching measurements."
    },
    {
        "anchor": "Hydrodynamic capture of microswimmers into sphere-bound orbits: Self-propelled particles can exhibit surprising non-equilibrium behaviors,\nand how they interact with obstacles or boundaries remains an important open\nproblem. Here we show that chemically propelled micro-rods can be captured,\nwith little change in their speed, into close orbits around solid spheres\nresting on or near a horizontal plane. We show that this interaction between\nsphere and particle is short-range, occurring even for spheres smaller than the\nparticle length, and for a variety of sphere materials. We consider a simple\nmodel, based on lubrication theory, of a force- and torque-free swimmer driven\nby a surface slip (the phoretic propulsion mechanism) and moving near a solid\nsurface. The model demonstrates capture, or movement towards the surface, and\nyields speeds independent of distance. This study reveals the crucial aspects\nof activity-driven interactions of self-propelled particles with passive\nobjects, and brings into question the use of colloidal tracers as probes of\nactive matter.",
        "positive": "Resolving structural modifications of colloidal glasses by combining\n  x-ray scattering and rheology: Glasses have liquid-like structure, but exhibit solid-like properties. A\ncentral question concerns the relation between the structure and mechanical\nproperties of glasses, but structural changes remain difficult to resolve. We\nuse a novel combination of rheology and x-ray scattering to resolve structural\nchanges in colloidal glasses and link them directly to their mechanical\nbehavior. By combining stress and structure factor measurements, we resolve\nshear induced changes in the nearest neighbor configuration as a function of\napplied stress, allowing us to elucidate the structural origin of the genuine\nshear banding transition of glasses."
    },
    {
        "anchor": "Charged rosettes at high and low ionic strengths: The complexation between a semiflexible polyelectrolyte and an oppositely\ncharged macroion leads to a multitude of structures ranging from tight\ncomplexes with the chain wrapped around the macroion to open multileafed\nrosette-like complexes. Rosette structures, expected to occur for short-ranged\nattractions between the macroion and the chain, have now also been seen in\nrecent Monte Carlo simulations with long-range (unscreened) interactions\n[Akinchina and Linse Macromolecules 2002, 35, 5183]. The current study provides\nscaling theories for both cases and shows that rosette structures are indeed\nquite robust against changes in the ionic strength. However, the transition\nfrom the wrapped to the rosette configuration has a dramatically different\ncharacteristics: The short-range case leads to a strongly discontinuous\ntransition into a rosette with large leaves whereas the long-range case occurs\nin a continuous fashion. We provide the complete diagram of states for both\ncases.",
        "positive": "Chirality-induced bacterial rheotaxis in bulk shear flows: Interaction of swimming bacteria with flows controls their ability to explore\ncomplex environments, crucial to many societal and environmental challenges and\nrelevant for microfluidic applications as cell sorting. Combining experimental,\nnumerical and theoretical analysis, we present a comprehensive study of the\ntransport of motile bacteria in shear flows. Experimentally, we obtain with\nhigh accuracy and for a large range of flow rates, the spatially resolved\nvelocity and orientation distributions. They are in excellent agreement with\nthe simulations of a kinematic model accounting for stochastic and\nmicrohydrodynamic properties and in particular the flagella chirality.\nTheoretical analysis reveals the scaling laws behind the average rheotactic\nvelocity at moderate shear rates using a chirality parameter and explains the\nreorientation dynamics leading to a saturation at large shear rates from the\nmarginal stability of a fixed point. Our findings constitute a full\nunderstanding of the physical mechanisms and relevant parameters of bacteria\nbulk rheotaxis."
    },
    {
        "anchor": "Structural Transitions in Fibers of Bent-Core Liquid Crystals from\n  Field-Theory Monte Carlo Simulations: Fibers of bent-core liquid crystals present an internal structure of a rolled\nsmectic layer and can be used as optical waveguides. We used a\nfield-theoretical Monte Carlo simulation to analyze the internal configuration\nof such fibers as a function of the radial coordinate and to study their\nequilibrium sates. In contrast to previous studies, we analyzed the fully\nnonlinear model proposed in [Bailey et al., Phys. Rev. E, 2007, 75, 031701] and\nrevised in [P\\'erez-Ortiz et al., Phys. Rev. E, 2011, 84, 011701]. We found\nthat, due to the non-differentiable character of such model, the Euler-Lagrange\nequations are not able to find all equilibrium states. Our Monte Carlo\nprocedure identified both differentiable and non-differentiable equilibria and\nfirst order transitions between them. In all cases, the equilibrium states show\ninhomogenous configurations that display a boundary layer. This methodology can\nby applied to other models of liquid crystals that have more degrees of\nfreedom, including those with non-differentiable minima. The equilibrium\nstructures found can be used as inputs to model the transmission of light along\nthe liquid crystal fibers.",
        "positive": "Rise time of spherical intruder in granular fluid: A model is developed to explain rise time of a spherical intruder placed in a\ngranular bed, which is considered as fluid. Phenomenon of rising intruder in a\ngranular bed is well known as Brazil nut effect. Radius of the intruder is\nvaried with $R_n = R_0 n, n = 1 .. 10$. An approximation for $t << \\tau$ is\nchosen in order to simplify the solution of second order differential equation\nof intruder vertical position to obtain the rise time T. A non-physical\nparameter $\\alpha$ and also transformation from $T$ to $T'$ are needed to be\nintroduced in order to control the results to mimic reported experiment\nqualitatively. Several forms of rise time $T_n$ and also transformed rise time\n$T_n'$ against $n$ are presented and discussed."
    },
    {
        "anchor": "End-Tethered Chains Increase the Local Glass Transition Temperature of\n  Matrix Chains by 45 K Next to Solid Substrates Independent of Chain Length: The local glass transition temperature Tg of pyrene-labeled polystyrene (PS)\nchains intermixed with end-tethered PS chains grafted to a neutral silica\nsubstrate was measured by fluorescence spectroscopy. To isolate the impact of\nthe grafted chains, the films were capped with bulk neat PS layers eliminating\ncompeting effects of the free surface. Results demonstrate that end-grafted\nchains strongly increase the local Tg of matrix chains by $\\approx$45 K\nrelative to bulk Tg, independent of grafted chain molecular weight from Mn =\n8.6 to 212 kg/mol and chemical end-group, over a wide range of grafting\ndensities $\\sigma$ = 0.003 to 0.33 chains/nm$^2$ spanning the mushroom-to-brush\ntransition regime. The tens-of-degree increase in local Tg resulting from\nimmobilization of the chain ends by covalent bonding in this athermal system\nsuggests a mechanism that substantially increases the local activation energy\nrequired for cooperative rearrangements.",
        "positive": "ProtAgents: Protein discovery via large language model multi-agent\n  collaborations combining physics and machine learning: Designing de novo proteins beyond those found in nature holds significant\npromise for advancements in both scientific and engineering applications.\nCurrent methodologies for protein design often rely on AI-based models, such as\nsurrogate models that address end-to-end problems by linking protein structure\nto material properties or vice versa. However, these models frequently focus on\nspecific material objectives or structural properties, limiting their\nflexibility when incorporating out-of-domain knowledge into the design process\nor comprehensive data analysis is required. In this study, we introduce\nProtAgents, a platform for de novo protein design based on Large Language\nModels (LLMs), where multiple AI agents with distinct capabilities\ncollaboratively address complex tasks within a dynamic environment. The\nversatility in agent development allows for expertise in diverse domains,\nincluding knowledge retrieval, protein structure analysis, physics-based\nsimulations, and results analysis. The dynamic collaboration between agents,\nempowered by LLMs, provides a versatile approach to tackling protein design and\nanalysis problems, as demonstrated through diverse examples in this study. The\nproblems of interest encompass designing new proteins, analyzing protein\nstructures and obtaining new first-principles data -- natural vibrational\nfrequencies -- via physics simulations. The concerted effort of the system\nallows for powerful automated and synergistic design of de novo proteins with\ntargeted mechanical properties. The flexibility in designing the agents, on one\nhand, and their capacity in autonomous collaboration through the dynamic\nLLM-based multi-agent environment on the other hand, unleashes great potentials\nof LLMs in addressing multi-objective materials problems and opens up new\navenues for autonomous materials discovery and design."
    },
    {
        "anchor": "Particle dynamics simulation of wet granulation in a rotating drum: We simulate the granulation process of solid spherical particles in the\npresence of a viscous liquid in a horizontal rotating drum by using molecular\ndynamics simulations in three dimensions. The numerical approach accounts for\nthe cohesive and viscous effects of the binding liquid, which is assumed to be\ntransported by wet particles and re-distributed homogeneously between wet\nparticles in contact. We investigate the growth of a single granule introduced\ninto the granular bed and the cumulative numbers of accreted and eroded\nparticles as a function of time for a range of values of material parameters\nsuch as mean particle size, size polydispersity, friction coefficient, and\nliquid viscosity. We find that the granule growth is an exponential function of\ntime, reflecting the decrease of the number of free wet particles. The\ninfluence of material parameters on the accretion and erosion rates reveals the\nnontrivial dynamics of the granulation process. It opens the way to a\ngranulation model based on the realistic determination of particle-scale\nmechanisms of granulation.",
        "positive": "Hydrodynamic Swarming of Thermally Active Dimeric Colloids: Self-propelled phoretic colloids have recently emerged as a promising avenue\nfor the design of artificial swimmers. These swimmers combine purely phoretic\ninteractions with intricate hydrodynamics which critically depend on the\nswimmer shape. Thermophobic dimer shaped colloids are here investigated by\nmeans of hydrodynamic simulations, from the single particle motion to their\ncollective behavior. The combination of phoretic repulsion with hydrodynamic\nlateral attraction favors the formation of planar moving clusters. The\nresulting hydrodynamic assembly in flattened swarms is therefore very specific\nto these dimeric active colloids."
    },
    {
        "anchor": "On the molecular theory of dimer liquid crystals: We present a statistical mechanics approximation scheme for the explicit\ntreatment of spacer-mediated configurational correlations among the mesogenic\nunits that form a dimer molecule. The approximation is applied to the\ndescription of the nematic phase of linear uniaxial dimers interacting via a\nstandard molecular pair-potential. Transition temperatures, order parameters\nand pair correlation averages are calculated for different spacer lengths. The\nresults readily reproduce the experimentally observed trends of phase\ntransition thermodynamics and of dipolar correlations deduced from dielectric\nstudies.",
        "positive": "Power-law friction in closely-packed granular materials: In order to understand the nature of friction in closely-packed granular\nmaterials, a discrete element simulation on granular layers subjected to\nisobaric plain shear is performed. It is found that the friction coefficient\nincreases as the power of the shear rate, the exponent of which does not depend\non the material constants. Using a nondimensional parameter that is known as\nthe inertial number, the power-law can be cast in a generalized form so that\nthe friction coefficients at different confining pressures collapse on the same\ncurve. We show that the volume fraction also obeys a power-law."
    },
    {
        "anchor": "Pinning-induced folding-unfolding asymmetry in adhesive creases: The compression of soft elastic matter and biological tissue can lead to\ncreasing, an instability where a surface folds sharply into periodic\nself-contacts. Intriguingly, the unfolding of the surface upon releasing the\nstrain is usually not perfect: small scars remain that serve as nuclei for\ncreases during repeated compressions. Here we present creasing experiments with\nsticky polymer surfaces, using confocal microscopy, which resolve the contact\nline region where folding and unfolding occurs. It is found that surface\ntension induces a second fold, at the edge of the self-contact, which leads to\na singular elastic stress and self-similar crease morphologies. However, these\nprofiles exhibit an intrinsic folding-unfolding asymmetry that is caused by\ncontact line pinning, in a way that resembles wetting of liquids on imperfect\nsolids. Contact line pinning is therefore a key element of creasing: it\ninhibits complete unfolding and gives soft surfaces a folding memory.",
        "positive": "Non-Hermitian Topological Metamaterials with Odd Elasticity: We establish non-Hermitian topological mechanics in one dimensional (1D) and\ntwo dimensional (2D) lattices consisting of mass points connected by meta-beams\nthat lead to odd elasticity. Extended from the \"non-Hermitian skin effect\" in\n1D systems, we demonstrate this effect in 2D lattices in which bulk elastic\nwaves exponentially localize in both lattice directions. We clarify a proper\ndefinition of Berry phase in non-Hermitian systems, with which we characterize\nthe lattice topology and show the emergence of topological modes on lattice\nboundaries. The eigenfrequencies of topological modes are complex due to the\nbreaking of $\\mathcal{PT}$-symmetry and the excitations could exponentially\ngrow in time in the damped regime. Besides the bulk modes, additional localized\nmodes arise in the bulk band and they are easily affected by perturbations.\nThese distinguishing features may manifest themselves in various active\nmaterials and biological systems."
    },
    {
        "anchor": "Many-body correlations are non-negligible in both fragile and strong\n  glassformers: It is widely believed that the emergence of slow glassy dynamics is encoded\nin a material's microstructure. First-principles theory [mode-coupling theory\n(MCT)] is able to predict the dramatic slowdown of the dynamics from only\nstatic two-point correlations as input, yet it cannot capture all of the\nobserved dynamical behavior. Here we go beyond two-point spatial correlation\nfunctions by extending MCT systematically to include higher-order static and\ndynamic correlations. We demonstrate that only adding the static triplet direct\ncorrelations already qualitatively changes the predicted glass-transition\ndiagram of binary hard spheres and silica. Moreover, we find a non-trivial\ncompetition between static triplet correlations that work to stabilize the\nglass state, and dynamic higher-order correlations which destabilize it for\nboth materials. We conclude that the conventionally neglected static triplet\ndirect correlations as well as higher-order dynamic correlations are in fact\nnon-negligible in both fragile and strong glassformers.",
        "positive": "Dense granular flow around a penetrating object: Experiments and\n  hydrodynamic model: We present in this Letter experimental results on the bidimensional flow\nfield around a cylinder penetrating into dense granular matter together with\ndrag force measurements. A hydrodynamic model based on extended kinetic theory\nfor dense granular flow reproduces well the flow localization close to the\ncylinder and the corresponding scalings of the drag force, which is found to\nnot depend on velocity, but linearly on the pressure and on the cylinder\ndiameter and weakly on the grain size. Such a regime is found to be valid at a\nlow enough \"granular\" Reynolds number."
    },
    {
        "anchor": "Theory of Freezing Point Depression in Charged Porous Media: Freezing in charged porous media can induce significant pressure and cause\ndamage to tissues and functional materials. We formulate a thermodynamically\nconsistent theory to model freezing phenomena inside charged heterogeneous\nporous space. Two regimes are distinguished: free ions in open pore space lead\nto negligible effects of freezing point depression and pressure. On the other\nhand, if nano-fluidic salt trapping happens, subsequent ice formation is\nsuppressed due to the high concentration of ions in the electrolyte. In this\ncase, our theory predicts that freezing starts at a significantly lower\ntemperature compared to pure water. In 1D, as the temperature goes even lower,\nice continuously grows, until the salt concentration reaches saturation, all\nions precipitate to form salt crystals, and freezing completes. Enormous\npressure can be generated if initial salt concentration is high before salt\nentrapment. We show modifications to the classical nucleation theory, due to\nthe trapped salt ions. Interestingly, although the freezing process is\nenormously changed by trapped salts, our analysis shows that the Gibbs-Thompson\nequation on confined melting point shift is not affected by the presence of the\nelectrolyte.",
        "positive": "Theory of the asymmetric ripple phase in achiral lipid membranes: We present a phenomenological theory of phase transitions in achiral lipid\nmembranes in terms of two coupled order parameters -- a scalar order parameter\ndescribing lipid chain melting, and a vector order parameter describing the\ntilt of the hydrocarbon chains below the chain-melting transition. Existing\ntheoretical models fail to account for all the observed features of the phase\ndiagram, in particular the detailed microstructure of the asymmetric ripple\nphase lying between the fluid and the tilted gel phase. In contrast, our\ntwo-component theory reproduces all the salient structural features of the\nripple phase, providing a unified description of the phase diagram and\nmicrostructure."
    },
    {
        "anchor": "Hydrodynamic interactions in dense active suspensions: from polar order\n  to dynamical clusters: We study the role of hydrodynamic interactions in the collective behaviour of\ncollections of microscopic active particles suspended in a fluid. We introduce\na novel calculational framework that allows us to separate the different\ncontributions to their collective dynamics from hydrodynamic interactions on\ndifferent length scales. Hence we are able to systematically show that\nlubrication forces when the particles are very close to each other play as\nimportant a role as long-range hydrodynamic interactions in determining their\nmany-body behaviour. We find that motility-induced phase separation is\nsuppressed by near-field interactions, leading to open gel-like clusters rather\nthan dense clusters. Interestingly, we find a globally polar ordered phase\nappears for neutral swimmers with no force dipole that is enhanced by near\nfield lubrication forces in which the collision process rather than long-range\ninteraction dominates the alignment mechanism.",
        "positive": "$N$-point free energy distribution function in one dimensional random\n  directed polymers: Explicit expression for the $N$-point free energy distribution function in\none dimensional directed polymers in a random potential is derived in terms of\nthe Bethe ansatz replica technique. The obtained result is equivalent to the\none derived earlier by Prolhac and Spohn [J. Stat. Mech., 2011, P03020]."
    },
    {
        "anchor": "Hydrodynamics of chiral liquids and suspensions: We obtain hydrodynamic equations describing a fluid consisting of chiral\nmolecules or a suspension of chiral particles in a Newtonian fluid. The\nstresses arising in a flowing chiral liquid have a component forbidden by\nsymmetry in a Newtonian liquid. For example, a chiral liquid in a Poiseuille\nflow between parallel plates exerts forces on the plates, which are\nperpendicular to the flow. A generic flow results in spatial separation of\nparticles of different chirality. Thus even a racemic suspension will exhibit\nchiral properties in a generic flow. A suspension of particles of random shape\nin a Newtonian liquid is described by equations which are similar to those\ndescribing a racemic mixture of chiral particles in a liquid.",
        "positive": "Statistical Analysis of Thermal Conductivity Experimentally Measured in\n  Water-Based Nanofluids: Nanofluids are suspensions of nanoparticles in a base heat-transfer liquid.\nThey have been widely investigated to boost heat transfer since they were\nproposed in the 1990's. We present a statistical correlation analysis of\nexperimentally measured thermal conductivity of water-based nanofluids\navailable in the literature. The influences of particle concentration, particle\nsize, temperature and surfactants are investigated. For specific materials\n(alumina, titania, copper oxide, copper, silica and silicon carbide), separate\nanalyses are performed. The conductivity increases with the concentration in\nqualitative agreement with Maxwell's theory of homogeneous media. The\nconductivity also increases with the temperature (in addition to the\nimprovement due to the increased conductivity with water). Surprisingly, only\nsilica nanofluids exhibit a statistically significant effect of particle size,\nwhereby smaller particles lead to faster heat transfer. Overall, the large\nscatter in the experimental data prevents a compelling, unambiguous assessment\nof these effects. Taken together, the results of our analysis suggest that more\ncomprehensive experimental characterizations of nanofluids are necessary to\nestimate their practical potential."
    },
    {
        "anchor": "Dynamic response of a thermoelectric cell induced by ion thermodiffusion: Aqueous electrolyte solutions under the influence of a temperature gradient\ncan generate thermoelectric fields, which arise from different responses of the\npositive and negative charges. This is related to the thermo diffusion effect\nwhich is quantified by the ionic heat of transport and the thermal diffusion\ncoefficient. When a solution is confined between two metallic electrodes with\ndifferent temperatures, it is expected to measure the electrostatic potential\ndifference due to the thermoelectric field. We performed experiments in aqueous\nelectrolyte solutions, and our results show that a thermoelectric field appears\ninstantly in the solution as the temperature difference between the electrodes\nstabilizes. This field arises from the trend to separate both ionic charges in\nthe temperature gradient. The experimental results also show that a slow change\nin the potential difference is observed, which is related to thermodiffusion in\nthe entire cell. These results are important to understand how the\nthermoelectric response can be optimized, given the broad interest in the\nliterature to generate thermoelectric energy from thermoelectric cells.",
        "positive": "Molecular dynamics simulation of the capillary leveling of a\n  glass-forming liquid: Motivated by recent experimental studies probing i) the existence of a mobile\nlayer at the free surface of glasses, and ii) the capillary leveling of polymer\nnanofilms, we study the evolution of square-wave patterns at the free surface\nof a generic glass-forming binary Lennard-Jones mixture over a wide temperature\nrange, by means of molecular dynamics simulations. The pattern's amplitude is\nmonitored and the associated decay rate is extracted. The evolution of the\nlatter as a function of temperature exhibits a crossover between two distinct\nbehaviours, over a temperature range typically bounded by the glass-transition\ntemperature and the mode-coupling critical temperature. Layer-resolved analysis\nof the film particles' mean-squared displacements further shows that diffusion\nat the surface is considerably faster than in the bulk, below the\nglass-transition temperature. The diffusion coefficient of the surface\nparticles is larger than its bulk counterpart by a factor that reaches 105 at\nthe lowest temperature studied. This factor decreases upon heating, in\nagreement with recent experimental studies."
    },
    {
        "anchor": "Hydrodynamics for a granular binary mixture at low density: Hydrodynamic equations for a binary mixture of inelastic hard spheres are\nderived from the Boltzmann kinetic theory. A normal solution is obtained via\nthe Chapman-Enskog method for states near the local homogeneous cooling state.\nThe mass, heat, and momentum fluxes are determined to first order in the\nspatial gradients of the hydrodynamic fields, and the associated transport\ncoefficients are identified. In the same way as for binary mixtures with\nelastic collisions, these coefficients are determined from a set of coupled\nlinear integral equations. Practical evaluation is possible using a Sonine\npolynomial approximation, and is illustrated here by explicit calculation of\nthe relevant transport coefficients: the mutual diffusion, the pressure\ndiffusion, the thermal diffusion, the shear viscosity, the Dufour coefficient,\nthe thermal conductivity, and the pressure energy coefficient. All these\ncoefficients are given in terms of the restitution coefficients and the ratios\nof mass, concentration, and particle sizes. Interesting and new effects arise\nfrom the fact that the reference states for the two components have different\npartial temperatures, leading to additional dependencies of the transport\ncoefficients on the concentration. The results hold for arbitrary degree of\ninelasticity and are not limited to specific values of the parameters of the\nmixture. Applications of this theory will be discussed in subsequent papers.",
        "positive": "Liquid-Liquid Phase Separation in an Elastic Network: Living and engineered systems rely on the stable coexistence of two\ninterspersed liquid phases. Yet surface tension drives their complete\nseparation. Here we show that stable droplets of uniform and tuneable size can\nbe produced through arrested phase separation in an elastic matrix. Starting\nwith an elastic polymer network swollen by a solvent mixture, we change the\ntemperature or composition to drive demixing. Droplets nucleate and grow to a\nstable size that is tuneable by the network cross-linking density, the cooling\nrate, and the composition of the solvent mixture. We discuss thermodynamic and\nmechanical constraints on the process. In particular, we show that the\nthreshold for macroscopic phase separation is altered by the elasticity of the\npolymer network, and we highlight the role of internuclear correlations in\ndetermining the droplet size and polydispersity. This phenomenon has potential\napplications ranging from colloid synthesis and structural colour to phase\nseparation in biological cells."
    },
    {
        "anchor": "Theory of polygonal phases self-assembled from T-shaped liquid\n  crystalline molecules: Extensive experimental studies have shown that numerous ordered phases can be\nformed via the self-assembly of T-shaped liquid crystalline molecules (TLCMs)\ncomposed of a rigid backbone, two flexible end chains and a flexible side\nchain. However, a comprehensive understanding of the stability and formation\nmechanisms of these intricately nanostructured phases remains incomplete. Here\nwe fill this gap by carrying out a theoretical study of the phase behaviour of\nTLCMs. Specifically, we construct phase diagrams of TLCMs by computing the free\nenergy of different ordered phases of the system. Our results reveal that the\nnumber of polygonal edges increases as the length of side chain or interaction\nstrength increases, consistent with experimental observations. The theoretical\nstudy not only reproduces the experimentally observed phases and phase\ntransition sequences, but also systematically analyzes the stability mechanism\nof the polygonal phases.",
        "positive": "Dynamics of elastically strained islands in presence of an anisotropic\n  surface energy: The equilibrium solutions and coarsening dynamics of strained semi-conductor\nislands are investigated analytically and numerically. We develop an analytical\nmodel to study the effect of surface energy anisotropy on the dynamics\ncoarsening of islands. We propose a simple model to explain the effect of this\nanisotropy on the coarsening time. We find that the anisotropy slows down the\ncoarsening. This effect is rationalised using a quasi-analytical description of\nthe island profile."
    },
    {
        "anchor": "Active transport: A kinetic description based on thermodynamic grounds: We show that active transport processes in biological systems can be\nunderstood through a local equilibrium description formulated at the mesoscale,\nthe scale to describe stochastic processes. This new approach uses the method\nestablished by nonequilibrium thermodynamics to account for the irreversible\nprocesses occurring at this scale and provides nonlinear kinetic equations for\nthe rates in terms of the driving forces. The results show that the application\ndomain of nonequilibrium thermodynamics method to biological systems goes\nbeyond the linear domain. A model for transport of Ca$^{2+}$ by the\nCa$^{2+}$-ATPase, coupled to the hydrolysis of adenosine-triphosphate is\nanalyzed in detail showing that it depends on the reaction Gibbs energy in a\nnon-linear way. Our results unify thermodynamic and kinetic descriptions,\nthereby opening new perspectives in the study of different transport phenomena\nin biological systems.",
        "positive": "Non-linear screening of spherical and cylindrical colloids: the case of\n  1:2 and 2:1 electrolytes: From a multiple scale analysis, we find an analytic solution of spherical and\ncylindrical Poisson-Boltzmann theory for both a 1:2 (monovalent co-ions,\ndivalent counter-ions) and a 2:1 (reversed situation) electrolyte. Our approach\nconsists in an expansion in powers of rescaled curvature $1/(\\kappa a)$, where\n$a$ is the colloidal radius and $1/\\kappa$ the Debye length of the electrolytic\nsolution. A systematic comparison with the full numerical solution of the\nproblem shows that for cylinders and spheres, our results are accurate as soon\nas $\\kappa a>1$. We also report an unusual overshooting effect where the\ncolloidal effective charge is larger than the bare one."
    },
    {
        "anchor": "Two-phase flow of ferrofluids: Ferrofluids currently are the only type of magnetic liquid materials with\nwide practical use. The theory on ferrofluids is an example of success to apply\nstatistics to science. Ferrofluids are two-phase liquids consisting of\ndispersed nanoscale ferromagnetic particles suspended in a carrier fluid. Due\nto their tiny size, individual ferromagnetic particles clearly exhibit Brownian\nmotions. Only when a large number of randomly-moving particles are subject to\nan external magnetic field, can they collectively exhibit magnetization at a\nmacroscale. Using statistical theory, the magnetization of a ferrofluid can be\ncharacterized by the celebrated Langevin equation. The monograph combines\nstatistical theory and the method of Dirac function to establish equations for\nferrofluids under several conditions, including magnetization relaxation,\nmagnetization equilibrium, and magnetization freezing. It thus provides a quite\ncomplete account of the theory of ferrofluid dynamics.",
        "positive": "Monodisperse self-assembly in a model with protein-like interactions: We study the self-assembly behaviour of patchy particles with `protein-like'\ninteractions that can be considered as a minimal model for the assembly of\nviral capsids and other shell-like protein complexes. We thoroughly explore the\nthermodynamics and dynamics of self assembly as a function of the parameters of\nthe model and find robust assembly of all target structures considered. Optimal\nassembly occurs in the region of parameter space where a free energy barrier\nregulates the rate of nucleation, thus preventing the premature exhaustion of\nthe supply of monomers that can lead to the formation of incomplete shells. The\ninteractions also need to be specific enough to prevent the assembly of\nmalformed shells, but whilst maintaining kinetic accessibility. Free-energy\nlandscapes computed for our model have a funnel-like topography guiding the\nsystem to form the target structure, and show that the torsional component of\nthe interparticle interactions prevents the formation of disordered aggregates\nthat would otherwise act as kinetic traps."
    },
    {
        "anchor": "Dynamics of a deformable self-propelled domain: We investigate the dynamical coupling between the motion and the deformation\nof a single self-propelled domain based on two different model systems in two\ndimensions. One is represented by the set of ordinary differential equations\nfor the center of gravity and two tensor variables characterizing deformations.\nThe other is an active cell model which has an internal mechanism of motility\nand is represented by the partial differential equation for deformations.\nNumerical simulations show a rich variety of dynamics, some of which are common\nto the two model systems. The origin of the similarity and the difference is\ndiscussed.",
        "positive": "A Dynamic Renormalization Group Study of Active Nematics: We carry out a systematic construction of the coarse-grained dynamical\nequation of motion for the orientational order parameter for a two-dimensional\nactive nematic, that is a nonequilibrium steady state with uniaxial, apolar\norientational order. Using the dynamical renormalization group, we show that\nthe leading nonlinearities in this equation are marginally \\textit{irrelevant}.\nWe discover a special limit of parameters in which the equation of motion for\nthe angle field of bears a close relation to the 2d stochastic Burgers\nequation. We find nevertheless that, unlike for the Burgers problem, the\nnonlinearity is marginally irrelevant even in this special limit, as a result\nof of a hidden fluctuation-dissipation relation. 2d active nematics therefore\nhave quasi-long-range order, just like their equilibrium counterparts"
    },
    {
        "anchor": "Characterization of a Freezing/Melting Transition in a Vibrated and\n  Sheared Granular Medium: We describe experiments on monodisperse spherical particles in an annular\ncell geometry, vibrated from below and sheared from above. This system shows a\nfreezing/melting transition such that under sufficient vibration a crystallized\nstate is observed, which can be melted by sufficient shear. We characterize the\nhysteretic transition between these two states, and observe features\nreminiscent of both a jamming transition and critical phenomena.",
        "positive": "DNA-coated Functional Oil Droplets: Many industrial soft materials often include oil-in-water (O/W) emulsions at\nthe core of their formulations. By using tuneable interface stabilizing agents,\nsuch emulsions can self-assemble into complex structures. DNA has been used for\ndecades as a thermoresponsive highly specific binding agent between hard and,\nrecently, soft colloids. Up until now, emulsion droplets functionalized with\nDNA had relatively low coating densities and were expensive to scale up. Here a\ngeneral O/W DNA-coating method using functional non-ionic amphiphilic block\ncopolymers, both diblock and triblock, is presented. The hydrophilic\npolyethylene glycol ends of the surfactants are functionalized with azides,\nallowing for efficient, dense and controlled coupling of dibenzocyclooctane\nfunctionalized DNA to the polymers through a strain-promoted alkyne-azide click\nreaction. The protocol is readily scalable due to the triblock's commercial\navailability. Different production methods (ultrasonication, microfluidics and\nmembrane emulsification) are used with different oils (hexadecane and silicone\noil) to produce functional droplets in various size ranges (sub-micron, $\\sim\n20\\,\\mathrm{\\mu m}$ and $> 50\\,\\mathrm{\\mu m}$), showcasing the generality of\nthe protocol. Thermoreversible sub-micron emulsion gels, hierarchical\n\"raspberry\" droplets and controlled droplet release from a flat DNA-coated\nsurface are demonstrated. The emulsion stability and polydispersity is\nevaluated using dynamic light scattering and optical microscopy. The generality\nand simplicity of the method opens up new applications in soft matter and\nbiotechnological research and industrial advances."
    },
    {
        "anchor": "Controlling the self-assembly of binary copolymer mixtures in solution\n  through molecular architecture: We present a combined experimental and theoretical study on the role of\ncopolymer architecture in the self-assembly of binary PEO-PCL mixtures in\nwater-THF, and show that altering the chain geometry and composition of the\ncopolymers can control the form of the self-assembled structures and lead to\nthe formation of novel aggregates. First, using transmission electron\nmicroscopy and turbidity measurements, we study a mixture of sphere-forming and\nlamella-forming PEO-PCL copolymers, and show that increasing the molecular\nweight of the lamella-former at a constant ratio of its hydrophilic and\nhydrophobic components leads to the formation of highly-curved structures even\nat low sphere-former concentrations. This result is explained using a simple\nargument based on the effective volumes of the two sections of the diblock and\nis reproduced in a coarse-grained mean-field model: self-consistent field\ntheory (SCFT). Using further SCFT calculations, we study the distribution of\nthe two copolymer species within the individual aggregates and discuss how this\naffects the self-assembled structures. We also investigate a binary mixture of\nlamella-formers of different molecular weights, and find that this system forms\nvesicles with a wall thickness intermediate to those of the vesicles formed by\nthe two copolymers individually. This result is also reproduced using SCFT.\nFinally, a mixture of sphere-former and a copolymer with a large hydrophobic\nblock is shown to form a range of structures, including novel elongated\nvesicles.",
        "positive": "Particle Diffusion in Slow Granular Bulk Flows: We probe the diffusive motion of particles in slowly sheared three\ndimensional granular suspensions. For sufficiently large strains, the particle\ndynamics exhibits diffusive Gaussian statistics, with the diffusivity\nproportional to the local strain rate - consistent with a local, quasi static\npicture. Surprisingly, the diffusivity is also inversely proportional to the\ndepth of the particles within the flow - at the free surface, diffusivity is\nthus ill defined. We find that the crossover to Gaussian displacement\nstatistics is governed by the same depth dependence, evidencing a non-trivial\nstrain scale in three dimensional granular flows."
    },
    {
        "anchor": "Nonadditivity of Fluctuation-Induced Forces in Fluidized Granular Media: We investigate the effective long-range interactions between intruder\nparticles immersed in a randomly driven granular fluid. The effective\nCasimir-like force between two intruders, induced by the fluctuations of the\nhydrodynamic fields, can change its sign when varying the control parameters:\nthe volume fraction, the distance between the intruders, and the restitution\ncoefficient. More interestingly, by inserting more intruders, we verify that\nthe fluctuation-induced interaction is not pairwise additive. The simulation\nresults are qualitatively consistent with the theoretical predictions based on\nmode coupling calculations. These results shed new light on the underlying\nmechanisms of collective behaviors in fluidized granular media.",
        "positive": "Yield stress and elastic modulus of suspensions of noncolloidal\n  particles in yield stress fluids: We study experimentally the behavior of isotropic suspensions of noncolloidal\nparticles in yield stress fluids. This problem has been poorly studied in the\nliterature, and only on specific materials. In this paper, we manage to develop\nprocedures and materials that allow us to focus on the purely mechanical\ncontribution of the particles to the yield stress fluid behavior, independently\nof the physicochemical properties of the materials. This allows us to relate\nthe macroscopic properties of these suspensions to the mechanical properties of\nthe yield stress fluid and the particle volume fraction, and to provide results\napplicable to any noncolloidal particle in any yield stress fluid. We find that\nthe elastic modulus-concentration relationship follows a Krieger-Dougherty law,\nand we show that the yield stress-concentration relationship is related to the\nelastic modulus-concentration relationship through a very simple law, in\nagreement with results from a micromechanical analysis."
    },
    {
        "anchor": "Entropy production in the nonreciprocal Cahn-Hilliard model: We study the nonreciprocal Cahn-Hilliard model with thermal noise as a\nprototypical example of a generic class of non-Hermitian stochastic field\ntheories, analyzed in two companion papers [Suchanek, Kroy, Loos,\nArXiv:2303.16701 (2023); Suchanek, Kroy, Loos, ArXiv:2305.05633 (2023)]. Due to\nthe nonreciprocal coupling between two field components, the model is\ninherently out of equilibrium and can be regarded as an active field theory.\nBeyond the conventional homogeneous and static-demixed phases, it exhibits a\ntraveling-wave phase, which can be entered via either an oscillatory\ninstability or a critical exceptional point. By means of a Fourier\ndecomposition of the entropy production rate, we quantify the associated\nscale-resolved time-reversal symmetry breaking, in all phases and across the\ntransitions, in the low-noise regime. Our perturbative calculation reveals its\ndependence on the strength of the nonreciprocal coupling. Surging entropy\nproduction near the static-dynamic transitions can be attributed to\nentropy-generating fluctuations in the longest wavelength mode and heralds the\nemerging traveling wave. Its translational dynamics can be mapped on the\ndissipative ballistic motion of an active (quasi)particle.",
        "positive": "Contact angles on heterogeneous surfaces; a new look at Cassie's and\n  Wenzel's laws: We consider a three dimensional liquid drop sitting on a rough and chemically\nheterogeneous substrate. Using a novel minimization technique on the free\nenergy of this system, a generalized Young's equation for the contact angle is\nfound. In certain limits, the Cassie and Wenzel laws, and a new equivalent\nrule, applicable in general, are derived. We also propose an equation in the\nsame spirit as these results but valid on a more `microscopic' level.\nThroughout we work under the presence of gravity and keep account of line\ntension terms."
    },
    {
        "anchor": "Plateau-Rayleigh instability of a viscous film on a soft fiber: We theoretically study the Plateau-Rayleigh instability of a thin viscous\nfilm covering a fiber consisting of a rigid cylindrical core coated with a thin\ncompressible elastic layer. We develop a soft-lubrication model, combining the\ncapillary-driven flow in the viscous film to the elastic deformation of the\nsoft coating, within the Winkler-foundation framework. We perform a\nlinear-stability analysis and derive the dispersion relation. We find that the\ngrowth rate is larger when the soft coating is more compliant. As such,\nsoftness acts as a destabilising factor. In contrast, increasing the thickness\nof the soft coating reduces the growth rate, due to the dominating geometrical\neffect.",
        "positive": "Identifying structural flow defects in disordered solids using machine\n  learning methods: We use machine learning methods on local structure to identify flow defects -\nor regions susceptible to rearrangement - in jammed and glassy systems. We\napply this method successfully to two disparate systems: a two dimensional\nexperimental realization of a granular pillar under compression, and a\nLennard-Jones glass in both two and three dimensions above and below its glass\ntransition temperature. We also identify characteristics of flow defects that\ndifferentiate them from the rest of the sample. Our results show it is possible\nto discern subtle structural features responsible for heterogeneous dynamics\nobserved across a broad range of disordered materials."
    },
    {
        "anchor": "Overcharging of a macroion by an oppositely charged polyelectrolyte: The complexation of a polyelectrolyte with an oppositely charged spherical\nmacroion is studied for both salt free and salty solutions. When a\npolyelectrolyte winds around the macroion, its turns repel each other and form\nan almost equidistant coil. It is shown that this repulsive correlations of\nturns lead to the charge inversion: more polyelectrolyte winds around the\nmacroion than it is necessary to neutralize it. The charge inversion becomes\nstronger with increasing concentration of salt and can exceed 100%. This paper\nconfirms that correlations are the universal mechanism of charge inversion.",
        "positive": "Twist dynamics of semiflexible polymer: A number of strange results have been reported for the twist elasticity of a\nsemiflexible filament, actin. In particular dynamic and static methods for\ndetermining the torsional twist modulus give very different results. I show\nhere that internal losses (friction) in a semiflexible filament could be an\nimportant cause of dissipation and that the interpretation of dynamic\nexperiments should be made in terms of a storage and loss modulus for actin\nproteins."
    },
    {
        "anchor": "Self-Assembly of Patchy Particles into Polymer Chains: A Parameter-Free\n  Comparison between Wertheim Theory and Monte Carlo Simulation: We numerically study a simple fluid composed of particles having a hard-core\nrepulsion, complemented by two short-ranged attractive (sticky) spots at the\nparticle poles, which provides a simple model for equilibrium polymerization of\nlinear chains. The simplicity of the model allows for a close comparison, with\nno fitting parameters, between simulations and theoretical predictions based on\nthe Wertheim perturbation theory, a unique framework for the analytic\nprediction of the properties of self-assembling particle systems in terms of\nmolecular parameter and liquid state correlation functions. This theory has not\nbeen subjected to stringent tests against simulation data for ordering across\nthe polymerization transition. We numerically determine many of the\nthermodynamic properties governing this basic form of self-assembly (energy per\nparticle, order parameter or average fraction of particles in the associated\nstate, average chain length, chain length distribution, average end-to-end\ndistance of the chains, and the static structure factor) and find that\npredictions of the Wertheim theory accord remarkably well with the simulation\nresults.",
        "positive": "Geometrical control of active turbulence in curved topographies: We investigate the turbulent dynamics of a two-dimensional active nematic\nliquid crystal con- strained on a curved surface. Using a combination of\nhydrodynamic and particle-based simulations, we demonstrate that the\nfundamental structural features of the fluid, such as the topological charge\ndensity, the defect number density, the nematic order parameter and defect\ncreation and annihilation rates, are simple linear functions of the substrate\nGaussian curvature, which then acts as a control parameter for the chaotic\nflow. Our theoretical predictions are then compared with experiments on\nmicrotubule-kinesin suspensions confined on toroidal active droplets, finding\nexcellent qualitative agreement."
    },
    {
        "anchor": "Long-lived states in synchronized traffic flow. Empirical prompt and\n  dynamical trap model: The present paper proposes a novel interpretation of the widely scattered\nstates (called synchronized traffic) stimulated by Kerner's hypotheses about\nthe existence of a multitude of metastable states in the fundamental diagram.\nUsing single vehicle data collected at the German highway A1, temporal velocity\npatterns have been analyzed to show a collection of certain fragments with\napproximately constant velocities and sharp jumps between them. The particular\nvelocity values in these fragments vary in a wide range. In contrast, the flow\nrate is more or less constant because its fluctuations are mainly due to the\ndiscreteness of traffic flow.\n  Subsequently, we develop a model for synchronized traffic that can explain\nthese characteristics. Following previous work (I.A.Lubashevsky, R.Mahnke,\nPhys. Rev. E v. 62, p. 6082, 2000) the vehicle flow is specified by car\ndensity, mean velocity, and additional order parameters $h$ and $a$ that are\ndue to the many-particle effects of the vehicle interaction. The parameter $h$\ndescribes the multilane correlations in the vehicle motion. Together with the\ncar density it determines directly the mean velocity. The parameter $a$, in\ncontrast, controls the evolution of $h$ only. The model assumes that $a$\nfluctuates randomly around the value corresponding to the car configuration\noptimal for lane changing. When it deviates from this value the lane change is\ndepressed for all cars forming a local cluster. Since exactly the overtaking\nmanoeuvres of these cars cause the order parameter $a$ to vary, the evolution\nof the car arrangement becomes frozen for a certain time. In other words, the\nevolution equations form certain dynamical traps responsible for the long-time\ncorrelations in the synchronized mode.",
        "positive": "From Octopus to Dendrite - Semiflexible Polyelectrolyte Brush\n  Condensates in Trivalent Counterion Solution: Interplay between counterion-mediated interaction and stiffness inherent to\npolymer chain can bring substantial complexity to the morphology and dynamics\nof polyelectrolyte brush condensates. Trivalent counterions induce collapse of\nflexible polyelectrolyte brushes, over a certain range of grafting density,\ninto octopus-like surface micelles; however, if individual chains are rigid\nenough, the ion-mediated local nematic ordering assembles the brush chains into\nfractal-like dendritic condensates whose relaxation dynamics is significantly\nslower than that in the surface micelles. Notably, the trivalent ions condensed\nin the dendritic condensates are highly mobile displaying quasi-one-dimensional\ndiffusion in parallel along the dendritic branches. Our findings in this study\nare potentially of great significance to understanding the response of cellular\norganization such as chromosomes and charged polysaccharides on membranes to\nthe change in ionic environment."
    },
    {
        "anchor": "Highly nonlinear dynamics in a slowly sedimenting colloidal gel: We use a combination of original light scattering techniques and particles\nwith unique optical properties to investigate the behavior of suspensions of\nattractive colloids under gravitational stress, following over time the\nconcentration profile, the velocity profile, and the microscopic dynamics.\nDuring the compression regime, the sedimentation velocity grows nearly linearly\nwith height, implying that the gel settling may be fully described by a\n(time-dependent) strain rate. We find that the microscopic dynamics exhibit\nremarkable scaling properties when time is normalized by strain rate, showing\nthat the gel microscopic restructuring is dominated by its macroscopic\ndeformation.",
        "positive": "Critical Casimir effect in a disordered $O(2)$-symmetric model: Critical Casimir effect appears when critical fluctuations of an order\nparameter interact with classical boundaries. We investigate this effect in the\nsetting of a Landau-Ginzburg model with continuous symmetry in the presence of\nquenched disorder. The quenched free energy is written as an asymptotic series\nof moments of the models partition function. Our main result is that, in the\npresence of a strong disorder, Goldstone modes of the system contribute either\nwith an attractive or with a repulsive force. This result was obtained using\nthe distributional zeta-function method without relying on any particular\nansatz in the functional space of the moments of the partition function."
    },
    {
        "anchor": "Emergence of cooperativity in plasticity of soft glassy materials: The elastic coupling between plastic events is generally invoked to interpret\nplastic properties and failure of amorphous soft glassy materials. We report an\nexperiment where the emergence of a self-organized plastic flow is observed\nwell before the failure. For this we impose an homogeneous stress on a granular\nmaterial, and measure local deformations for very small strain increments using\na light scattering setup. We observe a non-homogeneous strain that appears as\ntransient bands of mesoscopic size and well defined orientation, different from\nthe angle of the macroscopic frictional shear band that appears at failure. The\npresence and the orientation of those micro-bands may be understood by\nconsidering how localized plastic reorganizations redistribute stresses in a\nsurrounding continuous elastic medium. We characterize the lengthscale and\npersistence of the structure. The presence of plastic events and the\nmesostructure of the plastic flow are compared to numerical simulations.",
        "positive": "DNA-Protein Cooperative Binding through Long-Range Elastic Coupling: Cooperativity plays an important role in the action of proteins bound to DNA.\nA simple, mechanical mechanism for cooperativity, in the form of a\ntension-mediated interaction between proteins bound to DNA at two different\nlocations is proposed. These proteins are not in direct physical contact. DNA\nsegments intercalating bound proteins are modeled as a Worm-Like Chain, which\nis free to deform in two dimensions. The tension-controlled protein-protein\ninteraction is the consequence of two effects produced by the protein binding.\nThe first is the introduction of a bend in the host DNA and the second is the\nmodification of the bending modulus of the DNA in the immediate vicinity of the\nbound protein. The interaction between two bound proteins may be either\nattractive or repulsive, depending on their relative orientation on the DNA.\nApplied tension controls both the strength and the range of protein-protein\ninteractions in this model. Properties of the cooperative interaction are\ndiscussed, along with experimental implications."
    },
    {
        "anchor": "Why clothes don't fall apart: tension transmission in staple yarns: The problem of how staple yarns transmit tension is addressed within abstract\nmodels in which the Amontons-Coulomb friction laws yield a linear programming\n(LP) problem for the tensions in the fiber elements. We find there is a\npercolation transition such that above the percolation threshold the\ntransmitted tension is in principle unbounded, We determine that the mean slack\nin the LP constraints is a suitable order parameter to characterize this\nsupercritical state. We argue the mechanism is generic, and in practical terms\ncorresponds to a switch from a ductile to a brittle failure mode accompanied by\na significant increase in mechanical strength.",
        "positive": "Ordered qausi-two-dimensional structure of nanoparticles in\n  semiflexiblering polymer brushes under compression: Molecular Dynamics (MD) simulations are presented for a coarse-grained\nbead-spring model of ring polymer brushes under compression. Flexible polymer\nbrushes are always disordered during compression, whereas semiflexible brushes\ntend to be ordered under sufficiently strong compression. Besides, the polymer\nmonomer density of semiflexible polymer brush is very high near the polymer\nbrush surface, inducing a peak value of free energy near the polymer brush\nsurface. Therefore, by compressing nanoparticles (NPs) in semiflexible ring\nbrush system, NPs tend to exhibit a closely packed single layer structure\nbetween the brush surface and the impenetrable wall, which provide a new access\nof designing responsive applications."
    },
    {
        "anchor": "Deep optical penetration dynamics in photo-bending: We model both the photo-stationary state and dynamics of an illuminated,\nphoto-sensitive, glassy liquid crystalline sheet. To illustrate the interplay\nbetween local tilt $\\theta$ of the sheet, effective incident intensity,\ncurvature and dynamics, we adopt the simplest variation of local incident light\nintensity with angle, that is $\\cos\\theta$. The tilt in the stationary state\nnever overshoots the vertical, but maximum curvature could be seen in the\nmiddle of the sheet for intense light. In dynamics, overshoot and\nself-eclipsing arise, revealing how important moving fronts of light\npenetration are. Eclipsing is qualitatively as in the experiments of Ikeda and\nYu (2003).",
        "positive": "Rotational motion of a droplet induced by interfacial tension: Spontaneous rotation of a droplet induced by the Marangoni flow is analyzed\nin a two-dimensional system. The droplet with the small particle which supplies\na surfactant at the interface is considered. We calculated flow field around\nthe droplet using Stokes equation and found that advective nonlinearity breaks\nsymmetry for rotation. Theoretical calculation indicates that the droplet\nspontaneously rotates when the radius of the droplet is an appropriate size.\nThe theoretical results were validated through comparison with the experiments."
    },
    {
        "anchor": "A tensor density measure of topological charge in three dimensional\n  nematic phases: A path independent measure in order parameter space is introduced such that,\nwhen integrated along any closed contour in a three dimensional nematic phase,\nit yields the topological charge of any line defects encircled by the contour.\nA related measure, when integrated over either closed or open surfaces, reduces\nto known results for the charge associated with point defects (hedgehogs) or\nSkyrmions. We further define a tensor density, the disclination density tensor\n$\\mathbf{D}$, from which the location of a disclination line can be determined.\nThis tensor density has a dyadic decomposition near the line into its tangent\nand its rotation vector, allowing a convenient determination of both. The\ntensor $\\mathbf{D}$ may be nonzero in special configurations in which there are\nno defects (double-splay or double-twist configurations), and its behavior\nthere is provided. The special cases of Skyrmions and hedgehog defects are also\nexamined, including the computation of their topological charge from $\n\\mathbf{D}$.",
        "positive": "A Transient Bond Model for Dynamic Constraints in Meso-Scale\n  Coarse-Grained Systems: The dynamical properties of entangled polymers originate from the dynamic\nconstraints due to the uncrossability between polymer chains. We propose a\nhighly coarse-grained simulation model with transient bonds for such\ndynamically constrained systems. Based on the ideas of the responsive particle\ndynamics (RaPiD) model [P. Kindt and W. J. Briels, J. Chem. Phys. 127, 134901\n(2007)] and the multi-chain slip-spring model [T. Uneyama and Y. Masubuchi, J.\nChem. Phys. 137, 154902 (2012)], we construct the RaPiD type transient bond\nmodel as a coarse-grained slip-spring model. In our model, a polymer chain is\nexpressed as a single particle, and particles are connected by transient bonds.\nThe transient bonds modulate the dynamics of particles but they do not affect\nstatic properties in equilibrium. We show the relation between parameters for\nthe entangled polymer systems and those for the transient bond model. By\nperforming simulations based on the transient bond model, we show how model\nparameters affect the linear viscoelastic behavior and the diffusion behavior.\nWe also show that the viscoelastic behavior of entangled polymer systems can be\nwell reproduced by the transient bond model."
    },
    {
        "anchor": "Electric-field-induced nematic-cholesteric transition and 3-D director\n  structures in homeotropic cells: We study the phase diagram of director structures in cholesteric liquid\ncrystals of negative dielectric anisotropy in homeotropic cells of thickness d\nwhich is smaller than the cholesteric pitch p. The basic control parameters are\nthe frustration ratio d/p and the applied voltage U. Fluorescence Confocal\nPolarising Microscopy allows us to directly and unambiguously determine the 3-D\ndirector structures. The results are of importance for potential applications\nof the cholesteric structures, such as switchable gratings and eyewear with\ntunable transparency based.",
        "positive": "The Onsager-Machlup Integral for Non-reciprocal Systems with Odd\n  Elasticity: The variational principle of the Onsager-Machlup integral is used to describe\nthe stochastic dynamics of a micromachine, such as an enzyme, characterized by\nodd elasticity. The obtained most probable path is found to become\nnon-reciprocal in the presence of odd elasticity and is further related to the\nentropy production."
    },
    {
        "anchor": "Designing allostery-inspired response in mechanical networks: Recent advances in designing meta-materials have demonstrated that global\nmechanical properties of disordered spring networks can be tuned by selectively\nmodifying only a small subset of bonds. Here, using a computationally-efficient\napproach, we extend this idea in order to tune more general properties of\nnetworks. With nearly complete success, we are able to produce a strain between\nany pair of target nodes in a network in response to an applied source strain\non any other pair of nodes by removing only ~1% of the bonds. We are also able\nto control multiple pairs of target nodes, each with a different individual\nresponse, from a single source, and to tune multiple independent source/target\nresponses simultaneously into a network. We have fabricated physical networks\nin macroscopic two- and three-dimensional systems that exhibit these responses.\nThis targeted behavior is reminiscent of the long-range coupled conformational\nchanges that often occur during allostery in proteins. The ease with which we\ncreate these responses may give insight into why allostery is a common means\nfor the regulation of activity in biological molecules.",
        "positive": "Critical-like Features of Stress Response in Frictional Packings: The mechanical response of static, unconfined, overcompressed face centred\ncubic, granular arrays is studied using large-scale, discrete element method\nsimulations. Specifically, the stress response due to the application of a\nlocalised force perturbation - the Green function technique - is obtained in\ngranular packings generated over several orders of magnitude in both the\nparticle friction coefficient and the applied forcing. We observe crossover\nbehaviour in the mechanical state of the system characterised by the changing\nnature of the resulting stress response. The transition between anisotropic and\nisotropic stress response exhibits critical-like features through the\nidentification of a diverging length scale that distinguishes the spatial\nextent of anisotropic regions from those that display isotropic behaviour. A\nmultidimensional phase diagram is constructed that parameterises the response\nof the system due to changing friction and force perturbations."
    },
    {
        "anchor": "Non-Markovian modeling of non-equilibrium fluctuations and dissipation\n  in active viscoelastic biomatter: Based on a Hamiltonian that incorporates the elastic coupling between a\ntracer and active particles, we derive a generalized Langevin model for the\nnon-equilibrium mechanical response of active viscoelastic biomatter. Our model\naccounts for the power-law viscoelastic response of the embedding polymeric\nnetwork as well as for the non-equilibrium energy transfer between active and\ntracer particles. Our analytical expressions for the frequency-dependent\nresponse function and the positional autocorrelation function agree nicely with\nexperimental data for red blood cells and actomyosin networks with and without\nATP. The fitted effective active-particle temperature, elastic constants and\neffective friction coefficients of our model allow straightforward physical\ninterpretation.",
        "positive": "Exploring the complex free energy landscape of the simplest glass by\n  rheology: For amorphous solids, it has been intensely debated whether the traditional\nview on solids, in terms of the ground state and harmonic low energy\nexcitations on top of it, such as phonons, is still valid. Recent theoretical\ndevelopments of amorphous solids revealed the possibility of unexpectedly\ncomplex free energy landscapes where the simple harmonic picture breaks down.\nHere we demonstrate that standard rheological techniques can be used as\npowerful tools to examine non-trivial consequences of such complex free energy\nlandscapes. By extensive numerical simulations on a hard sphere glass under\nquasi-static shear at finite temperatures, we show that, above the so-called\nGardner transition density, the elasticity breaks down, the stress relaxation\nexhibits slow and aging dynamics, and the apparent shear modulus becomes\nprotocol-dependent. Being designed to be reproducible in laboratories, our\napproach may trigger explorations of the complex free energy landscapes of a\nlarge variety of amorphous materials."
    },
    {
        "anchor": "A Viscoelastic model of phase separation: We show here a general model of phase separation in isotropic condensed\nmatter, namely, a viscoelastic model. We propose that the bulk mechanical\nrelaxation modulus that has so far been ignored in previous theories plays an\nimportant role in viscoelastic phase separation in addition to the shear\nrelaxation modulus. In polymer solutions, for example, attractive interactions\nbetween polymers under a poor-solvent condition likely cause the transient\ngellike behavior, which makes both bulk and shear modes active. Although such\nattractive interactions between molecules of the same component exist\nuniversally in the two-phase region of a mixture, the stress arising from\nattractive interactions is asymmetrically divided between the components only\nin dynamically asymmetric mixtures such as polymer solutions and colloidal\nsuspensions. Thus, the interaction network between the slower components, which\ncan store the elastic energy against its deformation through bulk and shear\nmoduli, is formed. It is the bulk relaxation modulus associated with this\ninteraction network that is primarily responsible for the appearance of the\nsponge structure peculiar to viscoelastic phase separation and the phase\ninversion. We demonstrate that a viscoelastic model of phase separation\nincluding this new effect is a general model that can describe all types of\nisotropic phase separation including solid and fluid models as its special\ncases without any exception, if there is no coupling with additional order\nparameter. The physical origin of volume shrinking behavior during viscoelastic\nphase separation and the universality of the resulting spongelike structure are\nalso discussed.",
        "positive": "Self-assembly of polyhedral shells: A molecular dynamics study: The use of reduced models for investigating the self-assembly dynamics\nunderlying protein shell formation in spherical viruses is described. The\nspontaneous self-assembly of these polyhedral, supramolecular structures, in\nwhich icosahedral symmetry is a conspicuous feature, is a phenomenon whose\ndynamics remain unexplored; studying the growth process by means of computer\nsimulation provides access to the mechanisms underlying assembly. In order to\ncapture the more universal aspects of self-assembly, namely the manner in which\ncomponent shapes influence structure and assembly pathway, in this exploratory\nstudy low-resolution approximations are used to represent the basic protein\nbuilding blocks. Alternative approaches involving both irreversible and\nreversible assembly are discussed, models based on both schemes are introduced,\nand examples of the resulting behavior described."
    },
    {
        "anchor": "Metastable liquid-liquid phase transition in a single-component system\n  with only one crystal phase and no density anomaly: We investigate the phase behavior of a single-component system in 3\ndimensions with spherically-symmetric, pairwise-additive, soft-core\ninteractions with an attractive well at a long distance, a repulsive soft-core\nshoulder at an intermediate distance, and a hard-core repulsion at a short\ndistance, similar to potentials used to describe liquid systems such as\ncolloids, protein solutions, or liquid metals. We showed [Nature {\\bf 409}, 692\n(2001)] that, even with no evidences of the density anomaly, the phase diagram\nhas two first-order fluid-fluid phase transitions, one ending in a\ngas--low-density liquid (LDL) critical point, and the other in a\ngas--high-density liquid (HDL) critical point, with a LDL-HDL phase transition\nat low temperatures. Here we use integral equation calculations to explore the\n3-parameter space of the soft-core potential and we perform molecular dynamics\nsimulations in the interesting region of parameters. For the equilibrium phase\ndiagram we analyze the structure of the crystal phase and find that, within the\nconsidered range of densities, the structure is independent of the density.\nThen, we analyze in detail the fluid metastable phases and, by explicit\nthermodynamic calculation in the supercooled phase, we show the absence of the\ndensity anomaly. We suggest that this absence is related to the presence of\nonly one stable crystal structure.",
        "positive": "Hot nano-particles in polar or paramagnetic liquids interact as\n  monopoles: When neutral nano-particles are heated or cooled in a polar liquid, they will\ninteract with each other as if they carry an electrostatic charge that is\nproportional to the temperature difference between the particle and the\nsurrounding fluid. The same should hold for paramagnetic liquids, in which case\nthe nano-particles should behave as magnetic monopoles. However, the analogy\nwith electrostatics/magnetostatics is not complete: heated/cooled\nnano-particles do not move under the influence of an applied field. They\nshould, however, interact as monopoles."
    },
    {
        "anchor": "A lattice Boltzmann study of phase separation in liquid-vapor systems\n  with gravity: Phase separation of a two-dimensional van der Waals fluid subject to a\ngravitational force is studied by numerical simulations based on lattice\nBoltzmann methods (LBM) implemented with a finite difference scheme. A growth\nexponent $\\alpha=1$ is measured in the direction of the external force.",
        "positive": "Driven Transport on open filaments with inter-filament switching\n  processes: We study a two filament driven lattice gas model with oppositely directed\nspecies of particles moving on two parallel filaments with filament switching\nprocesses and particle inflow and outflow at filament ends. The filament\nswitching process is {\\it correlated} such that particles switch filaments with\nfinite probability only when oppositely directed particles meet on the same\nfilament. This model mimics some of the coarse grained features observed in\ncontext of microtubule (MT) based intracellular transport, wherein cellular\ncargo loaded and off-loaded at filament ends are transported on multiple\nparallel microtubule (MT) filaments and can switch between the parallel\nmicrotubule filaments. We focus on a regime where the filaments are weakly\ncoupled, such that filament switching rates scale inversely as the length of\nthe filament. We find that the interplay (off)loading processes at the\nboundaries and the filament switching process leads to some distinctive\nfeatures of the system. These features includes occurrence of variety of phases\nin the system with inhomogeneous density profiles including localized density\nshocks, density difference across the filaments and bidirectional current flows\nin the system. We analyze the system by developing a mean field (MF) theory and\ncomparing the results obtained from the MF theory with the Monte Carlo (MC)\nsimulations of the dynamics of the system. We find that the steady state\ndensity and current profiles of particles and the phase diagram obtained within\nthe MF picture matches quite well with MC simulation results. These findings\nmaybe useful for studying multi-filament intracellular transport."
    },
    {
        "anchor": "Flow and clogging in a silo with an obstacle above the orifice: In a recent paper [Zuriguel et al., Phys. Rev. Lett. 107, 278001 (2011)] it\nhas been shown that the presence of an obstacle above the outlet can\nsignificatively reduce the clogging probability of granular matter pouring from\na silo. The amount of this reduction strongly depends on the obstacle position.\nIn this work, we present new measurements to analyze different outlet sizes,\nextending foregoing results and revealing that the effect of the obstacle is\nenhanced as the outlet size is increased. In addition, the effect of the\nobstacle position on the flow rate properties and in the geometrical features\nof arches is studied. These results reinforce previous evidence of the pressure\nreduction induced by the obstacle. In addition, it is shown how the mean\navalanche size and the average flow rate are not necessarily linked. On the\nother hand, a close relationship is suggested between the mean avalanche size\nand the flow rate fluctuations.",
        "positive": "Structural properties of additive binary hard-sphere mixtures: An approach to obtain the structural properties of additive binary\nhard-sphere mixtures is presented. Such an approach, which is a nontrivial\ngeneralization of the one recently used for monocomponent hard-sphere fluids\n[S. Pieprzyk, A. C. Bra\\'nka, and D. M. Heyes, Phys. Rev. E 95, 062104 (2017)],\ncombines accurate molecular-dynamics simulation data, the pole structure\nrepresentation of the total correlation functions, and the Ornstein-Zernike\nequation. A comparison of the direct correlation functions obtained with the\npresent scheme with those derived from theoretical results stemming from the\nPercus-Yevick (PY) closure and the so-called rational-function approximation\n(RFA) is performed. The density dependence of the leading poles of the Fourier\ntransforms of the total correlation functions and the decay of the pair\ncorrelation functions of the mixtures are also addressed and compared to the\npredictions of the two theoretical approximations. A very good overall\nagreement between the results of the present scheme and those of the RFA is\nfound, thus suggesting that the latter (which is an improvement over the PY\napproximation) can safely be used to predict reasonably well the long-range\nbehavior, including the structural crossover, of the correlation functions of\nadditive binary hard-sphere mixtures."
    },
    {
        "anchor": "Tunable wrinkling of thin nematic liquid crystal elastomer sheets: Instabilities in thin elastic sheets, such as wrinkles, are of broad interest\nboth from a fundamental viewpoint and also because of their potential for\nengineering applications. Nematic liquid crystal elastomers offer a new form of\ncontrol of these instabilities through direct coupling between microscopic\ndegrees of freedom, resulting from orientational ordering of rod-like\nmolecules, and macroscopic strain. By a standard method of dimensional\nreduction, we construct a plate theory for thin sheets of nematic elastomer. We\nthen apply this theory to the study of the formation of wrinkles due to\ncompression of a thin sheet of nematic liquid crystal elastomer atop an elastic\nor fluid substrate. We find the scaling of the wrinkle wavelength in terms of\nmaterial parameters and the applied compression. The wavelength of the wrinkles\nis found to be non-monotonic in the compressive strain owing to the presence of\nthe nematic. Finally, due to soft modes, the critical stress for the appearance\nof wrinkles can be much higher than in an isotropic elastomer and depends\nnontrivially on the manner in which the elastomer was prepared.",
        "positive": "Phase diagram of mixtures of colloids and polymers in the thermal\n  crossover from good to $\u03b8$ solvent: We determine the phase diagram of mixtures of spherical colloids and neutral\nnonadsorbing polymers in the thermal crossover region between the $\\theta$\npoint and the good-solvent regime. We use the generalized free-volume theory\n(GFVT), which turns out to be quite accurate as long as $q = R_g/R_c\\lesssim 1$\n($R_g$ is the radius of gyration of the polymer and $R_c$ is the colloid\nradius). Close to the $\\theta$ point the phase diagram is not very sensitive to\nsolvent quality, while, close to the good-solvent region, changes of the\nsolvent quality modify significantly the position of the critical point and of\nthe binodals. We also analyze the phase behavior of aqueous solutions of\ncharged colloids and polymers, using the extension of GFVT proposed by Fortini\net al., J. Chem. Phys. 128, 024904 (2008)."
    },
    {
        "anchor": "On the hydrodynamics of swimming enzymes: Several recent experiments suggest that rather generally the diffusion of\nenzymes may be augmented through their activity. We demonstrate that such\nswimming motility can emerge from the interplay between the enzyme energy\nlandscape and the hydrodynamic coupling of the enzyme to its environment.\nSwimming thus occurs during the transit time of a transient allosteric change.\nWe estimate the velocity during the transition. The analysis of such a swimming\nmotion suggests the final stroke size is limited by the hydrodynamic size of\nthe enzyme. This limit is quite a bit smaller than the values that can be\ninferred from the recent experiments. We also show that one proposed\nexplanation of the experiments based on reaction heat effects can be ruled out\nusing an extended hydrodynamic analysis. These results lead us to propose an\nalternate explanation of the fluorescence correlation measurements.",
        "positive": "Chain trajectories, domain shapes and terminal boundaries in block\n  copolymers: The packing geometry of macromolecules in complex mesophases is of key\nimportance to self-organization in synthetic and biological soft materials.\nWhile approximate or heuristic models rely on often-untested assumptions about\nhow flexible molecules \"fit in\" to distinct locations of complex assemblies,\nphysical assemblies derive from ensembles of fluctuating conformations,\nobscuring the connection between mesophase geometry and the underlying\narrangements. Here, we present an approach to extract and analyze features of\nmolecular packing in diblock block copolymer (BCP) melts, a prototypical soft\nmatter system, based on the statistical description of chain conformations in\nself-consistent field (SCF) theory. We show how average BCP chain trajectories\nin ordered morphologies can be analyzed from the SCF-derived orientational\norder parameter of chain segments. We use these extracted trajectories to\nanalyze the features of local packing geometry, including chain bending and\ntilt, as well as the terminal boundaries that delineate distinct domains in\nordered BCP morphologies. We illustrate this analysis by focusing on measurable\nfeatures of packing frustration in 2D (columnar) and 3D (spherical and\nbicontinuous) morphologies, notably establishing an explicit link between chain\nconformations in complex morphologies and their medial geometry."
    },
    {
        "anchor": "Grain Dynamics in a Two-dimensional Granular Flow: We have used particle tracking methods to study the dynamics of individual\nballs comprising a granular flow in a small-angle two-dimensional funnel. We\nstatistically analyze many ball trajectories to examine the mechanisms of shock\npropagation. In particular, we study the creation of, and interactions between,\nshock waves. We also investigate the role of granular temperature and draw\nparallels to traffic flow dynamics.",
        "positive": "Molecular-Dynamics Simulation of a Glassy Polymer Melt: Incoherent\n  Scattering Function: We present simulation results for a model polymer melt, consisting of short,\nnonentangled chains, in the supercooled state. The analysis focuses on the\nmonomer dynamics, which is monitored by the incoherent intermediate scattering\nfunction. The scattering function is recorded over six decades in time and for\nmany different wave-vectors. The lowest temperatures studied are slightly above\nthe critical temperature of mode-coupling theory (MCT), which was determined\nfrom a quantitative analysis of the beta- and alpha-relaxations. We find\nevidence for the space-time factorization theorem in the beta-relaxation\nregime, and for the time-temperature superposition principle in the\nalpha-regime, if the temperature is not too close to the critical temperature.\nThe wave-vector dependence of the nonergodicity parameter, of the critical\namplitude, and the alpha-relaxation time are in qualitative agreement with\ncalculations for hard spheres. For wave-vectors larger than the maximum of the\nstructure factor the alpha-relaxation time already agrees fairly well with the\nasymptotic MCT-prediction. The behavior of the relaxation time at small\nwave-vectors can be rationalized by the validity of the Gaussian approximation\nand the value of the Kohlrausch stretching exponent."
    },
    {
        "anchor": "Solid-liquid coexistence of polydisperse fluids via simulation: We describe a simulation method for the accurate study of the equilibrium\nfreezing properties of polydisperse fluids under the experimentally relevant\ncondition of fixed polydispersity. The approach is based on the phase switch\nMonte Carlo method of Wilding and Bruce [Phys. Rev. Lett. {\\bf 85}, 5138\n(2000)]. This we have generalized to deal with particle size polydispersity by\nincorporating updates which alter the diameter $\\sigma$ of a particle, under\nthe control of a distribution of chemical potential differences\n$\\tilde\\mu(\\sigma)$. Within the resulting isobaric semi-grand canonical\nensemble, we detail how to adapt $\\tilde\\mu(\\sigma)$ and the applied pressure\nsuch as to study coexistence, whilst ensuring that the ensemble averaged\ndensity distribution $\\rho(\\sigma)$ matches a fixed functional form. Results\nare presented for the effects of small degrees of polydispersity on the\nsolid-liquid transition of soft spheres.",
        "positive": "Instabilities in liquid crystal elastomers: Stability is an important and fruitful avenue of research for liquid crystal\nelastomers. At constant temperature, upon stretching, the homogeneous state of\na nematic body becomes unstable, and alternating shear stripes develop at very\nlow stress. Moreover, these materials can experience classical mechanical\neffects, such as necking, void nucleation and cavitation, and inflation\ninstability, which are inherited from their polymeric network. We investigate\nthe following two problems: First, how do instabilities in nematic bodies\nchange from those found in purely elastic solids? Second, how are these\nphenomena modified if the material constants fluctuate? To answer these\nquestions, we present a systematic study of instabilities occurring in nematic\nliquid crystal elastomers, and examine the contribution of the nematic\ncomponent and of fluctuating model parameters that follow probability laws.\nThis combined analysis may lead to more realistic estimations of subsequent\nmechanical damage in nematic solid materials."
    },
    {
        "anchor": "Dislocation loops in overheated free-standing smectic films: Static and dynamic phenomena in overheated free-standing smectic-A films are\nstudied using a generalization of de Gennes' theory for a confined presmectic\nliquid. A static application is to determine the profile of the film meniscus\nand the meniscus contact angle, the results being compared with those of a\nrecent study employing de Gennes' original theory. The dynamical generalization\nof the theory is based on on a time-dependent Ginzburg-Landau approach. This is\nused to compare two modes for layer-thinning transitions in overheated films,\nnamely \"uniform thinning\" vs. nucleation of dislocation loops. Properties such\nas the line tension and velocity of a moving dislocation line are evaluated\nself-consistently by the theory.",
        "positive": "Sandpile formation by revolving rivers: Experimental observation of a new mechanism of sandpile formation is\nreported. As a steady stream of dry sand is poured onto a horizontal surface, a\npile forms which has a thin river of sand on one side flowing from the apex of\nthe pile to the edge of its base. The river rotates about the pile, depositing\na new layer of sand with each revolution, thereby growing the pile. For small\npiles the river is steady and the pile formed is smooth. For larger piles, the\nriver becomes intermittent and the surface of the pile becomes undulating. The\nfrequency of revolution of the river is measured as the pile grows and the\nresults are explained with a simple scaling argument. The essential features of\nthe system that produce the phenomena are discussed."
    },
    {
        "anchor": "Hydrodynamics of chiral squirmers: Many microorganisms take a chiral path while swimming in an ambient uid. In\nthis paper, we study the combined behavior of two chiral swimmers using the\nwell-known squirmer model taking into account chiral asymmetries. In contrast\nto the simple squirmer model, which has an axisymmetric distribution of slip\nvelocity, the chiral squirmer has additional asymmetries in the surface slip,\nwhich contribute to both translations and rotations of the motion. As a result,\nswimming trajectories can become helical and chiral asymmetries arise in the ow\npatterns. We study the swimming trajectories of a pair of chiral squirmers that\ninteract hydrodynamically. This interaction can lead to attraction and\nrepulsion, and in some cases even to bounded states where the swimmers continue\nto periodically orbit around a common average trajectory. Such bound states are\na signature of the chiral nature of the swimmers. Our study could be relevant\nto the collective movements of ciliated microorganisms.",
        "positive": "Linear instability of planar shear banded flow of both diffusive and\n  non-diffusive Johnson-Segalman fluids: We consider the linear stability of shear banded planar Couette flow of the\nJohnson-Segalman fluid, with and without the addition of stress diffusion to\nregularise the equations. In particular, we investigate the effect of\ntwo-dimensional perturbations representing undulations along the interface\nbetween shear bands. We demonstrate analytically that, for the linear stability\nproblem, the limit in which diffusion tends to zero is mathematically\nequivalent to a pure (non-diffusive) Johnson-Segalman model with a material\ninterface between the shear bands, provided the wavelength of perturbations\nbeing considered is long relative to the (short) diffusion lengthscale.\n  For no diffusion, we find that the flow is unstable to long waves for almost\nall arrangements of the two shear bands. Weak diffusion provides a small\nstabilising effect, rendering extremely long waves marginally stable. However,\nthe basic long-wave instability mechanism is not affected by this, and where\nthere would be instability as wavenumber k tends to 0 in the absence of\ndiffusion, we observe instability for moderate to long waves even with\ndiffusion.\n  This paper is the first full analytical investigation into an instability\nfirst documented in the numerical study of Physical Review Letters 95 (2005)\n134501 cond-mat/0501518. We discuss the relevance of this work to recent\nexperimental observations of complex dynamics seen in shear-banded flows."
    },
    {
        "anchor": "Jamming Transition and Inherent Structures of Hard Spheres and Discs: Recent studies show that volume fractions $\\phiJ$ at the jamming transition\nof frictionless hard spheres and discs are not uniquely determined but exist\nover a continuous range. Motivated by this observation, we numerically\ninvestigate dependence of $\\phiJ$ on the initial configurations of the parent\nfluids equilibrated at a fraction $\\phiini$, before compressing to generate a\njammed packing. We find that $\\phiJ$ remains constant when $\\phiini$ is small\nbut sharply increases when $\\phiini$ exceeds the dynamic transition point which\nthe mode-coupling theory predicts. We carefully analyze configurational\nproperties of both jammed packings and parent fluids and find that, while all\njammed packings remain isostatic, the increase of $\\phiJ$ is accompanied with\nsubtle but distinct changes of (i) local orders, (ii) a static length scale,\nand (iii) an exponent of the finite size scaling. These results quantitatively\nsupport the scenario of the random first order transition theoryof the glass\ntransition.",
        "positive": "Diffusivity and Hydrodynamic Drag of Nanoparticles at a Vapor-liquid\n  Interface: Measurements of the surface diffusivity of colloidal spheres translating\nalong a vapor/liquid inter- face show an unexpected decrease in diffusivity, or\nincrease in surface drag (from the Stokes-Einstein relation) when the particles\nsituate further into the vapor phase. However, direct measurements of the\nsurface drag from the colloid velocity due to an external force find the\nexpected decrease with deeper immersion into the vapor. The paradoxical drag\nincrease observed in diffusion experiments has been attributed to the\nattachment of the fluid interface to heterogeneities on the colloid surface,\nwhich causes the interface, in response to thermal fluctuations, to either jump\nor remain pinned, creating added drag. We have performed molecular dynamics\nsimulations of the diffusivity and force experiments for a nanoparticle with a\nrough surface at a vapor/liquid interface to examine the effect of contact line\nfluctuations. The drag calculated from both experiments agree and decrease as\nthe particle positions further into the vapor. The surface drag is smaller than\nthe bulk liquid drag due to the partial submersion into the liquid, and the\nfinite thickness of the interfacial zone relative to the nanoparticle size.\nContact line fluctuations do not give rise to an anomalous increase in drag."
    },
    {
        "anchor": "Two classes of events in sheared particulate matter: Under shear, a system of particles changes its contact network and becomes\nunstable as it transitions between mechanically stable states. For hard spheres\nat zero pressure, contact breaking events necessarily generate an instability,\nbut this is not the case at finite pressure, where we identify two types of\ncontact changes: network events that do not correspond to instabilities and\nrearrangement events that do. The relative fraction of such events is constant\nas a function of system size, pressure and interaction potential, consistent\nwith our observation that both nonlinearities obey the same finite-size\nscaling. Thus, the zero-pressure limit of the nonlinear response is highly\nsingular.",
        "positive": "Cyclic Bonds in Branched Polymers: In the gelation theory it has been implicitly assumed that (I) a cyclic bond\nis a finite bond that returns to itself; (II) cyclic bonds distribute at random\nin network structures. In this paper these two assumptions are reexamined from\na new point of view. The physical soundness of the assumptions is assessed\nthrough comparison with experimental observations."
    },
    {
        "anchor": "Substrate disorder promotes cell motility in confluent tissues: In vivo and in vitro cells rely on the support of an underlying biocompatible\nsubstrate, such as the extracellular matrix or a culture substrate, to spread\nand proliferate. The mechanical and chemical properties of such structures play\na central role in the dynamical and statistical properties of the tissue. At\nthe cell scale, these substrates are highly disordered. Here, we investigate\nhow spatial heterogeneities of the cell-substrate interaction influence the\nmotility of the cells in a model confluent tissue. We use the Self-Propelled\nVoronoi model and describe the disorder as a spatially dependent preferred\ngeometry of the individual cells. We found that when the characteristic length\nscale of the preferred geometry is smaller than the cell size, the tissue is\nless rigid than its homogeneous counterpart, with a consequent increase in cell\nmotility. This result is in sharp contrast to what has been reported for\ntissues with heterogeneity in the mechanical properties of the individual\ncells, where the disorder favors rigidity. Using the fraction of rigid cells,\nwe observe a collapse of the motility data for different model parameters and\nprovide evidence that the rigidity transition in the model tissue is\naccompanied by the emergence of a spanning cluster of rigid cells.",
        "positive": "Critical points, phase transitions and water-like anomalies for an\n  isotropic two length scale potential with increasing attractive well: Molecular Dynamic and Monte Carlo studies are performed in a family of\ncore-softened (CS) potential, composed by two length scales: a repulsive\nshoulder at short distances and the another a variable scale, that can be\nrepulsive or strongly attractive depending on the parameters used. The density,\ndiffusion and structural anomalous regions in the pressure versus temperature\nphase diagram shrink in pressure as the system becomes more attractive. The\nliquid-liquid transition appears as a consequence of the non monotonic behavior\nof the density versus pressure isotherms with the increase of the attraction\nwell. We found that the liquid-gas phase transition is Ising-like for all the\nCS potentials and its critical temperature increases with the increase of the\nattraction. No Ising-like behavior for the liquid-liquid phase transition was\ndetected in the Monte Carlo simulations what might be due to the presence of\nstable solid phases."
    },
    {
        "anchor": "Interfaces in Diblocks: A Study of Miktoarm Star Copolymers: We study AB$_n$ miktoarm star block copolymers in the strong segregation\nlimit, focussing on the role that the AB interface plays in determining the\nphase behavior. We develop an extension of the kinked-path approach which\nallows us to explore the energetic dependence on interfacial shape. We consider\na one-parameter family of interfaces to study the columnar to lamellar\ntransition in asymmetric stars. We compare with recent experimental results. We\ndiscuss the stability of the A15 lattice of sphere-like micelles in the context\nof interfacial energy minimization. We corroborate our theory by implementing a\nnumerically exact self-consistent field theory to probe the phase diagram and\nthe shape of the AB interface.",
        "positive": "Activity Induced Enhanced Diffusion of a Polymer in Poor Solvent: By means of Brownian dynamics simulations we study the steady-state dynamic\nproperties of a flexible active polymer in a poor solvent condition. Our\nresults show that the effective diffusion constant of the polymer $D_{\\rm eff}$\ngets significantly enhanced as activity increases, much like in active\nparticles. The simulation data are in agreement with a theoretically\nconstructed Rouse model of active polymer, demonstrating that irrespective of\nthe strength of activity, the long-time dynamics of the polymer chain is\ncharacterized by a universal Rouse-like scaling $D_{\\rm eff} \\sim N^{-1}$,\nwhere $N$ is the chain length."
    },
    {
        "anchor": "Screening of hydrodynamic interactions for polyelectrolytes in salt\n  solution: We provide numerical evidence that hydrodynamic interactions are screened for\ncharged polymers in salt solution on time scales below the Zimm time. At very\nshort times, a crossover to hydrodynamic behavior is observed. Our conclusions\nare drawn from extensive coarse-grained computer simulations of\npolyelectrolytes in explicit solvent and explicit salt, and discussed in terms\nof analytical arguments based on the Debye-Hueckel approximation.",
        "positive": "Force Percolation Transition of Jammed Granular Systems: The mechanical and transport properties of jammed materials originate from an\nunderlying per- colating network of contact forces between the grains. Using\nextensive simulations we investigate the force-percolation transition of this\nnetwork, where two particles are considered as linked if their interparticle\nforce overcomes a threshold. We show that this transition belongs to the random\npercolation universality class, thus ruling out the existence of long-range\ncorrelations between the forces. Through a combined size and pressure scaling\nfor the percolative quantities, we show that the continuous force percolation\ntransition evolves into the discontinuous jamming transition in the zero\npressure limit, as the size of the critical region scales with the pressure."
    },
    {
        "anchor": "Dielectric decrement as a source of ion specific effects: Many theoretical studies were devoted in the past to ion-specific effects,\ntrying to interpret a large body of experimental evidence, such as surface\ntension at air/water interfaces and force measurements between charged objects.\nAlthough several mechanisms were suggested to explain the results, such as\ndispersion forces and specific surface-ion interactions, we would like to\nsuggest another source of ion-specificity, originating from the local\nvariations of the dielectric constant due to the presence of ions in the\nsolution. We present a mean-field model to account for the heterogeneity of the\ndielectric constant caused by the ions. In particular, for ions that decrease\nthe dielectric constant we find a depletion of ions from the vicinity of\ncharged surfaces. For a two-plate system, the same effect leads to an increase\nof the pressure in between two surfaces. Our results suggest that the effect of\nions on the local dielectric constant should be taken into account when\ninterpreting experiments that address ion-specific effects.",
        "positive": "Ring conformations in bidisperse blends of ring polymers: The size of rings (also called cyclic polymers) in bidisperse blends of\nchemically identical rings is analyzed by computer simulations. Data of\nentangled ring blends and blends of interpenetrating rings are compared and it\nis shown that the compression of entangled rings can be explained by the\nchanges in the penetrable fraction of the minimal surface bounded by the ring.\nCorrections for small rings can be approximated by a concatenation probability\n$1-P_{OO}$ that a ring entraps at least one other ring. Both results are in\nline with a previous work [1] to explain the compression of entangled rings in\nmonodisperse melts. Bond-bond correlations in melts of interpenetrating rings\nlead to similar corrections for ring sizes as reported previously [2] for\nmonodisperse linear melts. For entangled rings, bond-bond correlations show an\nanti-correlation peak at a curvilinear distance of about ten segments that\ncoincides with a horizontal tangent in the normalized mean square internal\ndistances along the ring. Both observations become independent of melt\nmolecular weight for sufficiently large degrees of polymerization and such\nbehavior is not found in samples with entanglements switched off. In\nconsequence, the length scale of topological interactions (entanglement length)\nin a melt of entangled rings must be considered as constant in contrast to a\nrecent proposal by Sakaue [3]."
    },
    {
        "anchor": "Molecular Dynamics Simulation Study of Nonconcatenated Ring Polymers in\n  a Melt: I. Statics: Molecular dynamics simulations were conducted to investigate the structural\nproperties of melts of nonconcatenated ring polymers and compared to melts of\nlinear polymers. The longest rings were composed of N=1600 monomers per chain\nwhich corresponds to roughly 57 entanglement lengths for comparable linear\npolymers. For the rings, the radius of gyration squared was found to scale as N\nto the 4/5 power for an intermediate regime and N to the 2/3 power for the\nlarger rings indicating an overall conformation of a crumpled globule. However,\nalmost all beads of the rings are \"surface beads\" interacting with beads of\nother rings, a result also in agreement with a primitive path analysis\nperformed in the following paper (DOI: 10.1063/1.3587138). Details of the\ninternal conformational properties of the ring and linear polymers as well as\ntheir packing are analyzed and compared to current theoretical models.",
        "positive": "Role of material properties and mesostructure on dynamic deformation and\n  shear instability in Al-W granular composites: Dynamic experiments with Al-W granular/porous composites revealed\nqualitatively different behavior with respect to shear localization depending\non bonding between Al particles. Two-dimensional numerical modeling was used to\nexplore the mesomechanics of the large strain dynamic deformation in Al-W\ngranular/porous composites and explain the experimentally observed differences\nin shear localization between composites with various mesostructures.\nSpecifically, the bonding between the Al particles, the porosity, the roles of\nthe relative particle sizes of Al and W, the arrangements of the W particles,\nand the material properties of Al were investigated using numerical\ncalculations. It was demonstrated in simulations that the bonding between the\n\"soft\" Al particles facilitated shear localization as seen in the experiments.\nNumerical calculations and experiments revealed that the mechanism of the shear\nlocalization in granular composites is mainly due to the local high strain flow\nof \"soft\" Al around the \"rigid\" W particles causing localized damage\naccumulation and subsequent growth of the meso/macro shear bands/cracks. The\n\"rigid\" W particles were the major geometrical factor determining the\ninitiation and propagation of \"kinked\" shear bands in the matrix of \"soft\" Al\nparticles, leaving some areas free of extensive plastic deformation as observed\nin experiments and numerical calculations."
    },
    {
        "anchor": "Gravitational tempering in colloidal epitaxy to reduce defects further: Less-defective colloidal crystals can be used as photonic crystals. To this\nend, colloidal epitaxy was proposed in 1997 as a method to reduce the stacking\ndefects in the colloidal crystals. In this method, face-centered cubic (fcc)\n(001) stacking is forced by a template. In fcc (001) stacking, in contract to\nfcc {111} stacking, the stacking sequence is unique and thus the stacking fault\ncan be avoided. Additionally, in 1997, an effect of gravity that reduces the\nstacking disorder in hard-sphere (HS) colloidal crystals was found. Recently,\nwe have proposed a gravitational tempering method based on a result of Monte\nCarlo (MC) simulations using the HS model; after a colloidal crystal is grown\nin a relatively strong gravitational field, the defects can be reduced by\ndecreasing the gravity strength and maintain for a period of time. Here, we\ndemonstrate this method using MC simulations with a programed gravitation. The\ndramatic disappearance of defect structures is observed. Gravitational\ntempering can complement gravitational annealing; some defect structures that\naccidentally remain after gravitational annealing (keeping the colloidal\ncrystal under gravity of a considerable constant strength) can be erased.",
        "positive": "Note: \"Lock-in accelerometry\" to follow sink dynamics in shaken granular\n  matter: Understanding the penetration dynamics of intruders in granular beds is\nrelevant not only for fundamental Physics, but also for geophysical processes\nand construction on sediments or granular soils in areas potentially affected\nby earthquakes. While the penetration of intruders in two dimensional (2D)\nlaboratory granular beds can be followed using video recording, it is useless\nin three dimensional (3D) beds of non-transparent materials such as common\nsand. Here we propose a method to quantify the sink dynamics of an intruder\ninto laterally shaken granular beds based on the temporal correlations between\nthe signals from a reference accelerometer fixed to the shaken granular bed,\nand a probe accelerometer deployed inside the intruder. Due to its analogy with\nthe working principle of a lock in amplifier, we call this technique Lock in\naccelerometry (LIA). During Earthquakes, some soils can lose their ability to\nsustain shear and deform, causing subsidence and sometimes substantial building\ndamage due to deformation or tumbling"
    },
    {
        "anchor": "Multiple higher-order singularities and iso-dynamics in a simple\n  glass-former model: We investigate the slow dynamics of a colloidal model with two repulsive\nlength scales, whose interaction potential is the sum of a hard-core and a\nsquare shoulder. Despite the simplicity of the interactions, Mode-Coupling\ntheory predicts a complex dynamic scenario: a fluid-glass line with two\nreentrances and a glass-glass line ending with multiple higher-order ($A_3$ or\n$A_4$) singularities. In this work we verify the existence of the two $A_4$\npoints by numerical simulations, observing subdiffusive behaviour of the\nmean-square displacement and logarithmic decay of the density correlators.\nSurprisingly, we also discover a novel dynamic behaviour generated by the\ncompetition between the two higher-order singularities. This results in the\npresence of special loci along which the dynamics is identical \\textit{at all}\nlength and time scales.",
        "positive": "Importance of hydrodynamic shielding for the dynamic behavior of short\n  polyelectrolyte chains: The dynamic behavior of polyelectrolyte chains in the oligomer range is\ninvestigated with coarse-grained molecular dynamics simulation and compared to\ndata obtained by two different experimental methods, namely capillary\nelectrophoresis and electrophoresis NMR. We find excellent agreement of\nexperiments and simulations when hydrodynamic interactions are accounted for in\nthe simulations. We show that the electrophoretic mobility exhibits a maximum\nin the oligomer range and for the first time illustrate that this maximum is\ndue to the hydrodynamical shielding between the chain monomers. Our findings\ndemonstrate convincingly that it is possible to model dynamic behavior of\npolyelectrolytes using coarse grained models for both, the polyelectrolyte\nchains and the solvent induced hydrodynamic interactions."
    },
    {
        "anchor": "Stress-structure relation in dense colloidal melt under forward and\n  instantaneous reversal of shear: Dense supercooled colloidal melt in forward shear from a quiescent state\nshows overshoot in shear stress at 10% strain with an unchanged fluid structure\nat equal stress before and after overshoot. In addition, we find overshoot in\nnormal stress with a monotonic increase in osmotic pressure at an identical\nstrain. The first and second normal stress become comparable in magnitude and\nopposite in sign. Functional dependence of the steady state stress and osmotic\npressure with Peclet number demonstrate signature of crossover between\nNewtonian and nearly- Newtonian regime. Moreover, instantaneous shear reversal\nfrom steady state exhibit Bauschinger effect, where strong history dependence\nis observed depending on the time of flow reversal. The distribution of\nparticulate stress and osmotic pressure at the point of flow reversal is shown\nto be a signature of the subsequent response. We link the history dependence of\nthe stress-strain curves to changes in the fluid structure measured through the\nangular components of the radial distribution function. A uniform compression\nin transition from forward to reversed flowing state is found.",
        "positive": "The role of spontaneous curvature in the formation of cell membrane\n  necks: The mechanical effects of membrane compositional inhomogeneities are analyzed\nin a process analogous of neck formation in cellular membranes. We cast on the\nCanham-Helfrich model of fluid membranes with both the spontaneous curvature\nand the surface tension being non-homogeneous functions along the cell\nmembrane. The inhomogeneous distribution is determined by the equilibrium\nmechanical equations, and, in order to establish the role played by the\ninhomogeneity, we focus on the catenoid, a surface of zero mean curvature,\nwhich can be described in terms of the catenary curve parameterized by arc\nlength. We show that analytic solutions exist for the spontaneous curvature, as\nwell as for both, the surface tension and the radial elastic force. An analytic\nexpression for the constrictive force at the neck, is obtained. From the\nenergetic analysis, it is found that, if we fix the value of the constrictive\nforce at the neck, the set of solutions lies on two branches separated by an\nenergetic barrier. This barrier corresponds to the energy of the maximum\ncatenoid. If instead we fix the axial force, the solution has access to\ncatenoid of any size"
    },
    {
        "anchor": "Discontinuous shear modulus determines the glass transition temperature: A solid - amorphous or crystalline - is defined by a finite shear modulus\nwhile a fluid lacks such. We thus experimentally investigate the elastic\nproperties of a colloidal glass former near the glass transition: spectroscopy\nof vibrational excitations yields the dispersion relations of longitudinal and\ntransverse phonons in the glassy state. From the long wavelength limit of the\ndispersion relation we extract the bulk and the shear modulus. As expected, the\nlatter disappear in a fluid and we measure a clearly resolved discontinuous\nbehaviour of the elastic moduli at the glass transition. This not only\ndetermines the transition temperature T_G of the system but also directly\naddresses recent discussions about elasticity during vitrification. We show\nthat low frequency excitations in our system are plane waves such that\ncontinuum elasticity theory can be used to describe the macroscopic behaviour.",
        "positive": "Spatial mapping of the electron eigenfunctions in InAs self-assembled\n  quantum dots by magnetotunneling: We use magnetotunnelling spectroscopy as a non-invasive probe to produce\ntwo-dimensional spatial images of the probability density of an electron\nconfined in a self-assembled semiconductor quantum dot. The images reveal\nclearly the elliptical symmetry of the ground state and the characteristic\nlobes of the higher energy states."
    },
    {
        "anchor": "Domain Coarsening in Electroconvection: We report on experimental measurements of the growth of regular domains\nevolving from an irregular pattern in electroconvection. The late-time growth\nof the domains is consistent with the size of the domains scaling as $t^n$. We\nuse two isotropic measurements of the domain size: the structure factor and the\ndomain wall length. Measurements using the structure factor are consistent with\n$t^{1/5}$ growth. Measurements using the domain wall length are consistent with\n$t^{1/4}$ growth. One source of this discrepancy is the fact that the\ndistribution of local wavenumbers is approximately independent of the domain\nsize. In addition, we measure the anisotropy of the growing domains.",
        "positive": "Comment on \"Minimal size of a barchan dune\": It is now an accepted fact that the size at which dunes form from a flat sand\nbed as well as their `minimal size' scales on the flux saturation length. This\nlength is by definition the relaxation length of the slowest mode toward\nequilibrium transport. The model presented by Parteli, Duran and Herrmann\n[Phys. Rev. E 75, 011301 (2007)] predicts that the saturation length decreases\nto zero as the inverse of the wind shear stress far from the threshold. We\nfirst show that their model is not self-consistent: even under large wind, the\nrelaxation rate is limited by grain inertia and thus can not decrease to zero.\nA key argument presented by these authors comes from the discussion of the\ntypical dune wavelength on Mars (650 m) on the basis of which they refute the\nscaling of the dune size with the drag length evidenced by Claudin and\nAndreotti [Earth Pla. Sci. Lett. 252, 30 (2006)]. They instead propose that\nMartian dunes, composed of large grains (500 micrometers), were formed in the\npast under very strong winds. We show that this saltating grain size, estimated\nfrom thermal diffusion measurements, is not reliable. Moreover, the microscopic\nphotographs taken by the rovers on Martian aeolian bedforms show a grain size\nof 87 plus or minus 25 micrometers together with hematite spherules at\nmillimetre scale. As those so-called ``blueberries'' can not be entrained by\nreasonable winds, we conclude that the saltating grains on Mars are the small\nones, which gives a second strong argument against the model of Parteli et al."
    },
    {
        "anchor": "Lamellar to micellar phases and beyond: when tactic active systems admit\n  free-energy functionals: We consider microscopic models of active particles whose velocities,\nrotational diffusivities, and tumbling rates depend on the gradient of a local\nfield, which is either externally imposed or depends on all particle positions.\nDespite the fundamental differences between active and passive dynamics at the\nmicroscopic scale, we show that a large class of such tactic active systems\nadmit fluctuating hydrodynamics equivalent to those of interacting Brownian\ncolloids in equilibrium. We exploit this mapping to show how taxis may lead to\nthe lamellar and micellar phases observed for soft repulsive colloids. In the\ncontext of chemotaxis, we show how the competition between chemoattractant and\nchemorepellent may lead to a bona-fide equilibrium liquid-gas phase separation\nin which a loss of thermodynamic stability of the fluid signals the onset of a\nchemotactic collapse.",
        "positive": "Granular packing as model glass formers: Static granular packings are model hard-sphere glass formers. The nature of\nglass transition has remained a hotly debated issue. We review recent\nexperimental progresses in using granular materials to study glass transitions.\nWe focus on the growth of glass order with five-fold symmetry in granular\npackings and relate the findings to both geometric frustration and random\nfirst-order phase transition theories."
    },
    {
        "anchor": "Magnetotactic bacteria in a droplet self-assemble into a rotary motor: From intracellular protein trafficking to large scale motion of animal\ngroups, the physical concepts driving the self-organization of living systems\nare still largely unraveled. Selforganization of active entities, leading to\nnovel phases and emergent macroscopic properties, recently shed new lights on\nthese complex dynamical processes. Here we show that, under the application of\na constant magnetic field, motile magnetotactic bacteria confined in\nwater-in-oil droplets self-assemble into a rotary motor exerting a torque on\nthe external oil phase. A collective motion in the form of a large-scale\nvortex, reversable by inverting the field direction, builds-up in the droplet\nwith a vorticity perpendicular to the magnetic field. We study this collective\norganization at different concentrations, magnetic fields and droplets radii\nand reveal the formation of two torque-generating areas close to the droplet\ninterface. We characterize quantitatively the mechanical energy extractable\nfrom this new biological and self-assembled motor.",
        "positive": "Microgroove convexity is critical for robust gaseous layers on\n  hierarchically-structured superhydrophobic surfaces: Gaseous layers (plastrons) trapped on the surfaces of immersed hydrophobic\nsurfaces are critical for their function. Fibrillar morphologies offer a\nnatural pathway, yet they are limited to a narrow range of liquid-surface\nsystems and are vulnerable to pressure fluctuations that irreversibly destroy\nthe plastron. Inspired by the convexly grooved surfaces of water fern\n(Salvinia) leaves that support their fibrous outgrowths, we study the plastron\nformation on 3D-printed dual-scale surfaces with elliptical interconnected\nmicrogrooves. The groove curvature stabilizes a seed gas layer (SGL) that\nfacilitates plastron formation and restoration for all immersed hydrophobic\nsurfaces. Computations and theoretical calculations reveal that the SGL storage\ncapacity that sets the plastron robustness follows from the liquid menisci\nadaption to the groove geometry and pressure, and it can be further tuned using\nseparated grooves. Our study highlights groove convexity as a key morphological\nfeature for the design of multi-scale immersed surfaces for robust\nsuperhydrophobicity."
    },
    {
        "anchor": "The dependence of hydrophobic interactions on the solute size: Based on our recent study on physical origin of hydrophobic effects, this is\napplied to investigate the dependence of hydrophobic interactions on the solute\nsize. As two same hydrophobic solutes are dissolved into water, the hydration\nfree energy is determined, and the critical radius (Rc) is calculated to be 3.2\nAngstrom. With reference to the Rc, the dissolved behaviors can be divided into\ninitial and hydrophobic solvation processes. These can be demonstrated by the\nmolecular dynamics simulations on C60-C60 fullerenes in water, and CH4-CH4\nmolecules in water. In the association of C60 fullerenes in water, with\ndecreasing the separation between C60 fullerenes, hydrophobic interactions can\nbe divided into H1w and H2s hydrophobic processes, respectively. In addition,\nit can be derived that maximizing hydrogen bonding provides the driving force\nin the association of hydrophobic solutes in water.",
        "positive": "Polymorphism of syndiotactic polystyrene crystals from multiscale\n  simulations: Syndiotactic polystyrene (sPS) exhibits complex polymorphic behavior upon\ncrystallization. Computational modeling of polymer crystallization has remained\na challenging task because the relevant processes are slow on the molecular\ntime scale. We report herein a detailed characterization of sPS-crystal\npolymorphism by means of coarse-grained (CG) and atomistic (AA) modeling. The\nCG model, parametrized in the melt, shows remarkable transferability properties\nin the crystalline phase. Not only is the transition temperature in good\nagreement with atomistic simulations, it stabilizes the main $\\alpha$ and\n$\\beta$ polymorphs, observed experimentally. We compare in detail the\npropensity of polymorphs at the CG and AA level and discuss finite-size as well\nas box-geometry effects. All in all, we demontrate the appeal of CG modeling to\nefficiently characterize polymer-crystal polymorphism at large scale."
    },
    {
        "anchor": "Active glasses: Active glassy matter has recently emerged as a novel class of non-equilibrium\nsoft matter, combining energy-driven, active particle movement with dense and\ndisordered glass-like behavior. Here we review the state-of-the-art in this\nfield from an experimental, numerical, and theoretical perspective. We consider\nboth non-living and living active glassy systems, and discuss how several\nhallmarks of glassy dynamics (dynamical slowdown, fragility, dynamical\nheterogeneity, violation of the Stokes-Einstein relation, and aging) are\nmanifested in such materials. We start by reviewing the recent experimental\nevidence in this area of research, followed by an overview of the main\nnumerical simulation studies and physical theories of active glassy matter. We\nconclude by outlining several open questions and possible directions for future\nwork.",
        "positive": "Adhesive contact between a rigid body of arbitrary shape and a thin\n  elastic coating: Application of the principle of energy balance to a rigid indenter in contact\nwith elastic layer on a flat rigid substrate provides a very simple derivation\nof the detachment criterion which earlier has been obtained by much more\ncomplicated asymptotic analysis. This criterion allows calculating the adhesive\nstrength of arbitrary contact of a flat-ended indenter, which occurs to be\nproportional to the area of the face of the indenter and does not depend on its\nshape. Similarly, the adhesive contact problem can be easily solved in the case\nof arbitrary three-dimensional shape."
    },
    {
        "anchor": "Bicontinuous interfacially jammed emulsion gels with nearly uniform\n  sub-micrometer domains via regulated co-solvent removal: Porous materials possess numerous useful functions because of their high\nsurface area and ability to modulate the transport of heat, mass, fluids, and\nelectromagnetic waves. Unlike highly ordered structures, disordered porous\nstructures offer the advantages of ease of fabrication and high fault\ntolerance. Bicontinuous interfacially jammed emulsion gels (bijels) are\nkinetically trapped disordered biphasic materials that can be converted to\nporous materials with tunable features. Current methods of bijel fabrication\nresult in domains that are micrometers or larger, and non-uniform in size,\nlimiting their surface area, mechanical strength, and interaction with\nelectromagnetic waves. In this work, scalable synthesis of bijels with uniform\nand sub-micrometer domains is achieved via a two-step solvent removal process.\nThe resulting bijels are characterized quantitatively to verify the uniformity\nand sub-micrometer scale of the domains. Moreover, these bijels have structures\nthat resemble the microstructure of the scale of the white beetle Cyphochilus.\nWe find that such bijel films with relatively small thicknesses (< 150 um)\nexhibit strong solar reflectance as well as high brightness and whiteness in\nthe visible range. Considering their scalability in manufacturing, we believe\nthat VIPS-STRIPS bijels have great potential in large-scale applications\nincluding passive cooling, solar cells, and light emitting diodes (LEDs).",
        "positive": "Kinetic theory of discontinuous shear thickening of a moderately dense\n  inertial suspension of frictionless soft particles: We demonstrate that a discontinuous shear thickening (DST) can take place\neven in a moderately dense inertial suspension consisting of frictionless soft\nparticles. This DST can be regarded as an ignited-quenched transition in the\ninertial suspension. An approximate kinetic theory well recovers the results of\nthe Langevin simulation in the wide range of the volume fraction without any\nfitting parameters."
    },
    {
        "anchor": "Linear Dimensions of Adsorbed Semiflexible Polymers: What can be learned\n  about their persistence length?: Conformations of partially or fully adsorbed semiflexible polymer chains are\nstudied varying both contour length $L$, chain stiffness, $\\kappa$, and the\nstrength of the adsorption potential over a wide range. Molecular Dynamics\nsimulations show that partially adsorbed chains (with \"tails\", surface attached\n\"trains\" and \"loops\") are not described by the Kratky-Porod wormlike chain\nmodel. The crossover of the persistence length from its three-dimensional value\n$(\\ell_p)$ to the enhanced value in two dimensions $(2\\ell_p)$ is analyzed, and\nexcluded volume effects are identified for $L \\gg \\ell_p$. Consequences for the\ninterpretation of experiments are suggested. We verify the prediction that the\nadsorption threshold scales as $\\ell_p^{-1/3}$.",
        "positive": "Coarse grained dynamics of the freely cooling granular gas in one\n  dimension: We study the dynamics and structure of clusters in the inhomogeneous\nclustered regime of a freely cooling granular gas of point particles in one\ndimension. The coefficient of restitution is modeled as $r_0<1$ or 1 depending\non whether the relative speed is greater or smaller than a velocity scale\n$\\delta$. The effective fragmentation rate of a cluster is shown to rise\nsharply beyond a $\\delta$ dependent time scale. This crossover is coincident\nwith the velocity fluctuations within a cluster becoming order $\\delta$. Beyond\nthis crossover time, the cluster size distribution develops a nontrivial power\nlaw distribution, whose scaling properties are related to those of the velocity\nfluctuations. We argue that these underlying features are responsible behind\nthe recently observed nontrivial coarsening behaviour in the one dimensional\nfreely cooling granular gas."
    },
    {
        "anchor": "Water modeled as an intermediate element between carbon and silicon: Water and silicon are chemically dissimilar substances with common physical\nproperties. Their liquids display a temperature of maximum density, increased\ndiffusivity on compression, they form tetrahedral crystals and tetrahedral\namorphous phases. The common feature to water, silicon and carbon is the\nformation of tetrahedrally coordinated units. We exploit these similarities to\ndevelop a coarse-grained model of water (mW) that is essentially an atom with\ntetrahedrality intermediate between carbon and silicon. mW mimics the\nhydrogen-bonded structure of water through the introduction of a nonbond\nangular dependent term that encourages tetrahedral configurations. The model\ndeparts from the prevailing paradigm in water modeling: the use of long-ranged\nforces (electrostatics) to produce short-ranged (hydrogen-bonded) structure. mW\nhas only short-range interactions yet it reproduces the energetics, density and\nstructure of liquid water, its anomalies and phase transitions with comparable\nor better accuracy than the most popular atomistic models of water, at less\nthan 1% of the computational cost. We conclude that it is not the nature of the\ninteractions but the connectivity of the molecules that determines the\nstructural and thermodynamic behavior of water. The speedup in computing time\nprovided by mW makes it particularly useful for the study of slow processes in\ndeeply supercooled water, the mechanism of ice nucleation, wetting-drying\ntransitions, and as a realistic water model for coarse-grained simulations of\nbiomolecules and complex materials.",
        "positive": "Geometric mechanics of random kirigami: The presence of cuts in a thin planar sheet can dramatically alter its\nmechanical and geometrical response to loading, as the cuts allow the sheet to\ndeform strongly in the third dimension. We use numerical experiments to\ncharacterize the geometric mechanics of kirigamized sheets as a function of the\nnumber, size and orientation of cuts. We show that the geometry of mechanically\nloaded sheets can be approximated as a composition of simple developable units:\nflats, cylinders, cones and compressed Elasticae. This geometric construction\nyields simple scaling laws for the mechanical response of the sheet in both the\nweak and strongly deformed limit. In the ultimately stretched limit, this\nfurther leads to a theorem on the nature and form of geodesics in an arbitrary\nkirigami pattern, consistent with observations and simulations. By varying the\nshape and size of the geodesic in a kirigamized sheet, we show that we can\ncontrol the deployment trajectory of the sheet, and thence its functional\nproperties as a robotic gripper or a soft light window. Overall our study of\nrandom kirigami sets the stage for controlling the shape and shielding the\nstresses in thin sheets using cuts."
    },
    {
        "anchor": "Controlling Fragment Competition on Pathways to Addressable\n  Self-Assembly: Addressable self-assembly is the formation of a target structure from a set\nof unique molecular or colloidal building-blocks, each of which occupies a\ndefined location in the target. The requirement that each type of\nbuilding-block appears exactly once in each copy of the target introduces\nsevere restrictions on the combinations of particles and on the pathways that\nlead to successful self-assembly. These restrictions can limit the efficiency\nof self-assembly and the final yield of the product. In particular, partially\nformed fragments may compete with each other if their compositions overlap,\nsince they cannot be combined. Here, we introduce a \"completability\" algorithm\nto quantify competition between self-assembling fragments and use it to deduce\ngeneral principles for suppressing the effects of fragment incompatibility in\nthe self-assembly of small addressable clusters. Competition originates from\nloops in the bonding network of the target structure, but loops may be needed\nto provide structural rigidity and thermodynamic stability. An optimal\ncompromise can be achieved by careful choice of bonding networks and by\npromoting semi-hierarchical pathways that rule out competition between early\nfragments. These concepts are illustrated in simulations of self-assembly in\ntwo contrasting addressable targets of 20 unique components each.",
        "positive": "Cavitation of Water by Volume-Controlled Stretching: A liquid subjected to negative pressure is thermodynamically metastable.\nConfined within a small volume, negative pressure can build up until cavities\nform spontaneously. The critical negative pressure for cavitation in water has\nbeen theoretically predicted to be in the range of -100 to -200 MPa at room\ntemperature, whereas values around -30 MPa have been obtained by many\nexperiments. The discrepancy has yet to be resolved. In this study we perform\nmolecular dynamics simulations to study cavitation of water under volume\ncontrolled stretching. It is found that liquid water exhibits a nonlinear\nelastic compressibility (or stretchability) under hydrostatic tension and\nremains stable within the confined volume until spontaneous cavitation occurs\nat a critical strain. Subsequently, as the volume-controlled stretching\ncontinues, the cavity grows stably and the hydrostatic tension decreases\ncontinuously until the box volume is large enough for another transition to\nform a water droplet. A modified nucleation theory is proposed to predict the\ncritical condition for cavitation. In particular, a strong dependence of the\ncritical strain and stress for cavitation on the initial liquid volume is\npredicted by the modified nucleation theory, which may offer a possible\nexplanation for the discrepancies in the values of the critical negative\npressure obtained from experiments."
    },
    {
        "anchor": "Multistep kinetic self-assembly of DNA-coated colloids: Self-assembly is traditionally described as the process through which an\ninitially disordered system relaxes towards an equilibrium ordered phase only\ndriven by local interactions between its building blocks. However, This\ndefinition is too restrictive. Nature itself provides examples of amorphous,\nyet functional, materials assembled upon kinetically arresting the pathway\ntowards the ground state. Kinetic self-assembly is intrinsically more flexible\nand reliable than its equilibrium counterpart, allowing control over the\nmorphology of the final phase by tuning both the interactions and the\nthermodynamic pathway leading to kinetic arrest. Here we propose strategies to\ndirect the gelation of two-component colloidal mixtures by sequentially\nactivating selective interspecies and intra-species interactions. We\ninvestigate morphological changes in the structure of the arrested phases by\nmeans of event driven molecular dynamics (MD) simulations and experimentally\nusing DNA-coated colloids (DNACCs). Our approach can be exploited to finely\ntune the morphology of multicomponent nano- or micro-porous materials with\npossible applications in hybrid photovoltaics, photonics and drug delivery.",
        "positive": "Stripe dynamics in presence of disorder and lattice potentials: We study the influence of disorder and lattice pinning on the dynamics of a\ncharged stripe. Starting from a phenomenological model of a discrete quantum\nstring, we determine the phase diagram for this system. Three regimes are\nidentified, the free phase, the flat phase pinned by the lattice, and the\ndisorder pinned phase. In the absence of impurities, the system can be mapped\nonto a 1D array of Josephson junctions. The results are compared with\nmeasurements on nickelates and cuprates and a good qualitative agreement is\nfound between our results and the experimental data."
    },
    {
        "anchor": "Permeability of a bubble assembly: From the very dry to the wet limit: We measure the permeability of a fluidized bed of monodispersed bubbles with\nsoap solution characteristic of mobile and non-mobile interfaces. These\nexperimental data extend the permeability curves previously published for foam\nin the dry limit. In the wet limit, these data join the permeability curves of\na hard sphere suspension at porosity equal to 0.4 and 0.6 in the cases of\nmobile and non-mobile interfaces respectively. We show that the model of\npermeability proposed by Kozeny and Carman and originally validated for packed\nbeds of spheres (with porosity around 0.4) can be successfully applied with no\nadjustable parameters to liquid fractions from 0.001 up to 0.85 for systems\nmade of monodisperse and deformable entities with non-mobile interfaces.",
        "positive": "Diffusion mechanisms of localised knots along a polymer: We consider the diffusive motion of a localized knot along a linear polymer\nchain. In particular, we derive the mean diffusion time of the knot before it\nescapes from the chain once it gets close to one of the chain ends.\nSelf-reptation of the entire chain between either end and the knot position,\nduring which the knot is provided with free volume, leads to an L^3 scaling of\ndiffusion time; for sufficiently long chains, subdiffusion will enhance this\ntime even more. Conversely, we propose local ``breathing'', i.e., local\nconformational rearrangement inside the knot region (KR) and its immediate\nneighbourhood, as additional mechanism. The contribution of KR-breathing to the\ndiffusion time scales only quadratically, L^2, speeding up the knot escape\nconsiderably and guaranteeing finite knot mobility even for very long chains."
    },
    {
        "anchor": "Writhe formulas and antipodal points in plectonemic DNA configurations: The linking and writhing numbers are key quantities when characterizing the\nstructure of a piece of supercoiled DNA. Defined as double integrals over the\nshape of the double-helix, these numbers are not always straightforward to\ncompute, though a simplified formula exists. We examine the range of\napplicability of this widely-used simplified formula, and show that it cannot\nbe employed for plectonemic DNA. We show that inapplicability is due to a\nhypothesis of Fuller theorem that is not met. The hypothesis seems to have been\noverlooked in many works.",
        "positive": "Evidence for superfluid B-phase of 3He in aerogel: We have made simultaneous torsional oscillator and transverse cw NMR (at 165\nkHz) studies of the superfluid phase of 3He in aerogel glasses of 1% and 2% of\nsolid density. NMR occurs over a range of frequency extending from the Larmor\nfrequency to higher values, but strongly peaked at the Larmor value. This\nbehaviour together with the magnetic field independence of the effective\nsuperfluid density provides convincing evidence for a B-phase state with an n\ntexture, in our spherical geometry, governed by the same energetic\nconsiderations as for bulk superfluid 3He-B."
    },
    {
        "anchor": "Rheology of cohesive granular particles under constant pressure: The rheology of cohesive granular materials, under a constant pressure\ncondition, is studied using molecular dynamics simulations. Depending on the\nshear rate, pressure, and interparticle cohesiveness, the system exhibits four\ndistinctive phases: uniform shear, oscillation, shear-banding, and clustering.\nThe friction coefficient is found to increase with the inertial number,\nirrespective of the cohesiveness. The friction coefficient becomes larger for\nstrong cohesion. This trend is explained by the anisotropies of the\ncoordination number and angular distribution of the interparticle forces. In\nparticular, we demonstrate that the second-nearest neighbors play a role in the\nrheology of cohesive systems.",
        "positive": "Unexpected entanglement dynamics in semidilute blends of supercoiled and\n  ring DNA: Blends of polymers of different topologies, such as ring and supercoiled,\nnaturally occur in biology and often exhibit emergent viscoelastic properties\ncoveted in industry. However, due to their complexity, along with the\ndifficulty of producing polymers of different topologies, the dynamics of\ntopological polymer blends remains poorly understood. We address this void by\nusing both passive and active microrheology to characterize the linear and\nnonlinear rheological properties of blends of relaxed circular and supercoiled\nDNA. We characterize the dynamics as we vary the concentration from below the\noverlap concentration c* to above (0.5c* to 2c*). Surprisingly, despite working\nat the dilute-semidilute crossover, entanglement dynamics, such as\nshear-thinning, elastic plateaus, and multiple relaxation modes, emerge.\nFinally, blends exhibit an unexpected sustained elastic response to nonlinear\nstrains not previously observed even in well-entangled linear polymer\nsolutions."
    },
    {
        "anchor": "Phase transition to bundles of flexible supramolecular polymers: We report Monte Carlo simulations of the self-assembly of supramolecular\npolymers based on a model of patchy particles. We find a first-order phase\ntransition, characterized by hysteresis and nucleation, toward a solid bundle\nof polymers, of length much greater than the average gas phase length. We argue\nthat the bundling transition is the supramolecular equivalent of the\nsublimation transition, that results from a weak chain-chain interaction. We\nprovide a qualitative equation of state that gives physical insight beyond the\nspecific values of the parameters used in our simulations.",
        "positive": "Influence of wettability on liquid water transport in gas diffusion\n  layer of proton exchange membrane fuel cells (PEMFC): Water management is a key factor that limits PEFC's performance. We show how\ninsights into this problem can be gained from pore-scale simulations of water\ninvasion in a model fibrous medium. We explore the influence of contact angle\non the water invasion pattern and water saturation at breakthrough and show\nthat a dramatic change in the invasion pattern, from fractal to compact, occurs\nas the system changes from hydrophobic to hydrophilic. Then, we explore the\ncase of a system of mixed wettability, i.e. containing both hydrophilic and\nhydrophobic pores. The saturation at breakthrough is studied as a function of\nthe fraction of hydrophilic pores. The results are discussed in relation with\nthe water management problem, the optimal design of a GDL and the fuel cell\nperformance degradation mechanisms. We outline how the study could be extended\nto 3D systems, notably from binarised images of GDLs obtained by X ray\nmicrotomography."
    },
    {
        "anchor": "Strain stiffening universality in composite hydrogels and soft tissues: Soft biological tissues exhibit a remarkable resilience to large mechanical\nloads, a property which is associated with the strain stiffening capability of\nthe biopolymer networks that structurally support the tissues. Yet, recent\nstudies have shown that composite systems such as tissues and blood clots\nexhibit mechanical properties that contradict those of the polymer matrix -\ndemonstrating stiffening in compression, but softening in shear and tension.\nThe microscopic basis of this apparent paradox remains poorly understood. We\nshow that composite hydrogels and tissues do indeed exhibit non-linear elastic\nstiffening in shear - which is governed by the stretching of the polymer chains\nin the matrix - and that it is driven by the same mechanism that drives\ncompression stiffening. However, we show that the non-linear elastic stiffening\nin composite hydrogels and tissues is masked by mechanical dissipation arising\nfrom filler-polymer interactions known as the Mullins effect, and we introduce\na method to characterize the non-linear elasticity of the composites in\nisolation from this overall strain softening response through large-amplitude\noscillatory shear experiments. We present a comprehensive characterization of\nthe non-linear elastic strain stiffening of composite hydrogels and soft\ntissues, and show that the strain stiffening in shear and compression are both\ngoverned by universal strain amplification factors that depend on essential\nproperties of the composite system, such as the filler concentration and the\nfiller-polymer interaction strength. These results elucidate the microscopic\nmechanisms governing the non-linear mechanics of tissues, which provides design\nprinciples for engineering tissue-mimetic soft materials, and have broad\nimplications for cell-matrix mechanotransduction in living tissues under\nstrain.",
        "positive": "Molecular Structural Dynamics in Water-Ethanol Mixtures: Spectroscopy\n  with Polarized Neutrons Simultaneously Accessing Collective and\n  Self-Diffusion: Binary mixtures of water with lower alcohols display non-linear phase\nbehaviour upon mixing which are attributed to potential cluster formation at\nmolecular level. Unravelling such elusive structures requires the investigation\nof hydrogen-bonding sub-nanosecond dynamics. We employ high-resolution neutron\ntime-of-flight spectroscopy with polarization analysis in combination with\nselective deuteration to study the concentration-dependent structural dynamics,\nin the water rich part of the phase diagram of water-ethanol mixtures. This\nmethod enables the simultaneous access to atomic correlations in space and\ntime, and allows us to separate spatially incoherent scattering probing\nself-diffusion of the ethanol fraction from the coherent scattering probing\ncollective diffusion of the water network as a whole. Our observations indicate\nan enhanced rigidity of the hydrogen bond network at mesoscopic lengthscale\ncompared to the intra-molecular scale as the ethanol fraction increases, which\nis consistent with the hypothesis of clusters."
    },
    {
        "anchor": "Equation of state of sticky-hard-sphere fluids in the chemical-potential\n  route: The coupling-parameter method, whereby an extra particle is progressively\ncoupled to the rest of the particles, is applied to the sticky-hard-sphere\nfluid to obtain its equation of state in the so-called chemical-potential route\n($\\mu$ route). As a consistency test, the results for one-dimensional sticky\nparticles are shown to be exact. Results corresponding to the three-dimensional\ncase (Baxter's model) are derived within the Percus-Yevick approximation by\nusing different prescriptions for the dependence of the interaction potential\nof the extra particle on the coupling parameter. The critical point and the\ncoexistence curve of the gas-liquid phase transition are obtained in the $\\mu$\nroute and compared with predictions from other thermodynamics routes and from\ncomputer simulations. The results show that the $\\mu$ route yields a general\nbetter description than the virial, energy, compressibility, and\nzero-separation routes.",
        "positive": "Wetting dynamics on lyophilic solid surfaces patterned by lyophobic\n  islands: A theory for wetting of structured solid surfaces is developed, based on the\ndelta-comb periodic potential. It possesses two matching parameters: the\neffective line tension and the friction coefficient on the three-phase contact\nline at the surface. The theory is validated on the dynamics of spreading of\nliquid zinc droplets on morphologically patterned zinkophilic iron surface by\nmeans of square patterns of zinkophobic aluminum oxide. It is found that the\neffective line tension is negative and it has essential contribution to the\ndynamics of spreading. Thus, the theoretical analysis shows that the presence\nof lyophobic patterns situated on lyophilic surface makes the latter completely\nwettable, i.e. no equilibrium contact angle on such surface exists making the\ndroplet spread completely in form of thin liquid layer on the patterned\nsurface."
    },
    {
        "anchor": "Hysteretic transition from laminar to vortex shedding flow in soap films: There are different ways for fluid flow to become turbulent, but usually many\ninstabilities take place before that. Among these instabilities the transition\nfrom laminar flow to vortex shedding carries significant practical importance.\nHere we study a flow, where at high enough flow rates, vortices are generated\nby a fixed obstacle (cylinder), which penetrates a flowing, quasi-two\ndimensional soap film.\n  We present experimental results that demonstrate that the transition from\nlaminar flow to a periodic K\\'arm\\'an vortex street can be hysteretic, i.e.\nchanging the mean flow rate $\\bar V$ vortices can survive at velocities lower\nthan the velocity needed to generate them. This is an unexpected result since\n3D experiments are well described by the Hopf equation, which is incompatible\nwith hysteresis. Beyond that, our data cannot be satisfactorily fitted by the\ngeneric model of hysteresis, i.e. the 5th order Landau equation. It is found\nthat a phenomenological model describes our experimental findings very well.\n  Evidences are presented that wetting properties of the rod, mechanical\ninstabilities (i.e. vibrations) of the setup, and the effect of the surrounding\nair are not the cause of the hysteresis. To reduce three dimensional effects,\nthe rod was replaced by a disk having a thickness roughly eight times that of\nthe film. The replacement of the rod by a disk increases the gap width and the\nshedding frequency. Behaviour of the system (for instance the unstable\ntrajectory) in the hysteretic gap is investigated by means of transient\nmeasurements.",
        "positive": "An improved coarse-grained model of solvation and the hydrophobic effect: We present a coarse-grained lattice model of solvation thermodynamics and the\nhydrophobic effect that implements the ideas of Lum-Chandler-Weeks (LCW) theory\n[J. Phys. Chem. B 103, 4570 (1999)] and improves upon previous lattice models\nbased on it. Through comparison with molecular simulation, we show that our\nmodel captures the length-scale and curvature dependence of solvation free\nenergies with near-quantitative accuracy and two to three orders of magnitude\nless computational effort, and further, correctly describes the large but rare\nsolvent fluctuations that are involved in dewetting, vapor tube formation and\nhydrophobic assembly. Our model is intermediate in detail and complexity\nbetween implicit-solvent models and explicit-water simulations."
    },
    {
        "anchor": "Glass transition in monatomic systems: smearing of the same structure vs\n  two structure competition: In the present paper we discuss the properties of Voronoi polygons in several\nmonatomic glass-forming systems and compare them with those of the Kob-Andersen\nmixture. We show that two mechanisms of glass formation are possible: smearing\nof Voronoi polygons or formation of polygons of two different shapes. Both\nmechanisms lead to disturbance of the crystalline order in the system and glass\ntransition.",
        "positive": "Complex Dynamics of a Model of Sheared Nematogenic Fluids: Nonlinearities in constitutive equations of extended objects in shear flow\nlead to novel phenomena, {\\it e.g.} \"rheochaos\" in solutions of wormlike\nmicelles and \"elastic turbulence\" in polymer solutions. Since both phenomena\ninvolve anisotropic objects, their contributions to the deviatoric stress are\nlikely to be similar. However, these two fields have evolved rather\nindependently and an attempt at connecting these fields is still lacking. We\nshow that a minimal model in which the anisotropic nature of the constituting\nobjects is taken into account by a nematic alignment tensor field reproduces\nseveral statistical features found in rheochaos and elastic turbulence. We\nnumerically analyse the full non-linear hydrodynamic equations of a sheared\nnematic fluid under shear stress and strain rate controlled situations,\nincorporating spatial heterogeneity only in the gradient direction. For a\ncertain range of imposed stress and strain rates, this extended dynamical\nsystem shows signatures of \\textit{spatiotemporal chaos} and \\textit{transient\nshear banding}. In the chaotic regime the power spectra of the order parameter\nstress, velocity fluctuations and the total injected power show power law\nbehavior and the total injected power shows a non-gaussian, skewed probability\ndistribution. These dynamical features bear resemblance to \\textit{elastic\nturbulence} phenomena observed in polymer solutions. The scaling behavior is\nindependent of the choice of shear rate/stress controlled method."
    },
    {
        "anchor": "Toward a microscopic description of flow near the jamming threshold: We study the relationship between microscopic structure and viscosity in\nnon-Brownian suspensions. We argue that the formation and opening of contacts\nbetween particles in flow effectively leads to a negative selection of the\ncontacts carrying weak forces. We show that an analytically tractable model\ncapturing this negative selection correctly reproduces scaling properties of\nflows near the jamming transition. In particular, we predict that (i) the\nviscosity {\\eta} diverges with the coordination z as {\\eta} ~\n(z_c-z)^{-(3+{\\theta})/(1+{\\theta})}, (ii) the operator that governs flow\ndisplays a low-frequency mode that controls the divergence of viscosity, at a\nfrequency {\\omega}_min\\sim(z_c-z)^{(3+{\\theta})/(2+2{\\theta})}, and (iii) the\ndistribution of forces displays a scale f* that vanishes near jamming as\nf*/<f>\\sim(z_c-z)^{1/(1+{\\theta})} where {\\theta} characterizes the\ndistribution of contact forces P(f)\\simf^{\\theta} at jamming, and where z_c is\nthe Maxwell threshold for rigidity.",
        "positive": "Interaction Between Two Rows of Localized Adsorption Sites in a 2D\n  One-Component Plasma: We compute the free energy for two rows of localized adsorption sites\nembedded in a two dimensional one-component plasma with neutralizing background\ndensity $\\rho$. The interaction energy between the adsorption sites is\nrepulsive. We also compute the average occupation number of the adsorption\nsites and compare it to the result for a single row of sites. The exact result\nindicates that the discretization does not induce charge asymmetry and no\nattractive forces occur."
    },
    {
        "anchor": "Nonlinear elasticity of disordered fiber networks: Disordered biopolymer gels have striking mechanical properties including\nstrong nonlinearities. In the case of athermal gels (such as collagen-I) the\nnonlinearity has long been associated with a crossover from a bending dominated\nto a stretching dominated regime of elasticity. The physics of this crossover\nis related to the existence of a central-force isostatic point and to the fact\nthat for most gels the bending modulus is small. This crossover induces scaling\nbehavior for the elastic moduli. In particular, for linear elasticity such a\nscaling law has been demonstrated [Broedersz et al. Nature Physics, 2011 7,\n983]. In this work we generalize the scaling to the nonlinear regime with a\ntwo-parameter scaling law involving three critical exponents. We test the\nscaling law numerically for two disordered lattice models, and find a good\nscaling collapse for the shear modulus in both the linear and nonlinear\nregimes. We compute all the critical exponents for the two lattice models and\ndiscuss the applicability of our results to real systems.",
        "positive": "Anisotropic thermophoresis: Colloidal migration in temperature gradient is referred to as thermophoresis.\nIn contrast to particles with spherical shape, we show that elongated colloids\nmay have a thermophoretic response that varies with the colloid orientation.\nRemarkably, this can translate into a non-vanishing thermophoretic force in the\ndirection perpendicular to the temperature gradient. Oppositely to the friction\nforce, the thermophoretic force of a rod oriented with the temperature gradient\ncan be larger or smaller than when oriented perpendicular to it. The precise\nanisotropic thermophoretic behavior clearly depends on the colloidal rod aspect\nratio, and also on its surface details, which provides an interesting\ntunability to the devices constructed based on this principle. By means of\nmesoscale hydrodynamic simulations, we characterize this effect for different\ntypes of rod-like colloids."
    },
    {
        "anchor": "Buckling of 2D Plasma Crystals with Non-reciprocal Interactions: Laboratory realizations of 2D plasma crystals typically involve monodisperse\nmicroparticles confined into horizontal monolayers in radio-frequency (rf)\nplasma sheaths. This gives rise to the so-called plasma wakes beneath the\nmicroparticles. The presence of wakes renders the interactions in such systems\nnon-reciprocal, a fact that can lead to a quite different behaviour from the\none expected for their reciprocal counterparts. Here we examine the buckling of\na hexagonal 2D plasma crystal, occurring as the confinement strength is\ndecreased, taking explicitly into account the non-reciprocity of the system via\na well-established point-particle wake model. We observe that for a finite wake\ncharge, the monolayer hexagonal crystal undergoes a transition first to a\nbilayer hexagonal structure, unrealisable in harmonically confined reciprocal\nYukawa systems, and subsequently to a bilayer square structure. Our theoretical\nresults are confirmed by molecular dynamics simulations for experimentally\nrelevant parameters, indicating the potential of their observation in\nstate-of-the-art experiments with 2D complex plasmas.",
        "positive": "Physicochemical influences on electrohydrodynamic transport in\n  compressible packed beds of colloidal boehmite particles: Production and processing of colloidal particles require a deeper\nunderstanding of surface charge of particles and interaction of mass and charge\ntransport in packed beds. The assessment of fundamental parameters is rather\ncomplex due to the additional influence of the particle charge on the structure\nof a packed bed. The combination of different measurement techniques (streaming\npotential and electroosmosis) allows for separating the effects, based on the\npostulation of a new method to quantify the ratio of surface conductance to\nliquid conductance. The purpose of this paper is to investigate the influence\nof the pH value and compression on the electrohydrodynamic transport\nparameters."
    },
    {
        "anchor": "3D Printed Actuators: Reversibility, Relaxation and Ratcheting: Additive manufacturing strives to combine any combination of materials into\nthree dimensional functional structures and devices, ultimately opening up the\npossibility of 3D printed machines. It remains difficult to actuate such\ndevices, thus limiting the scope of 3D printed machines to passive devices or\nnecessitating the incorporation of external actuators that are manufactured\ndifferently. Here we explore 3D printed hybrid thermoplast/conducter bilayers,\nthat can be actuated by differential heating caused by externally controllable\ncurrents flowing through their conducting faces. We uncover the functionality\nof such actuators and show that they allow to 3D print, in one pass, simple\nflexible robotic structures that propel forward under step-wise applied\nvoltages. Moreover, exploiting the thermoplasticity of the non-conducting\nplastic parts at elevated temperatures, we show how strong driving leads to\nirreversible deformations - a form of 4D printing - which also enlarges the\nrange of linear response of the actuators. Finally, we show how to leverage\nsuch thermoplastic relaxations to accumulate plastic deformations and obtain\nvery large deformations by alternatively driving both layers of a bilayer; we\ncall this ratcheting. Our strategy is scalable and widely applicable, and opens\nup a new approach to reversible actuation and irreversible 4D printing of\narbitrary structures and machines.",
        "positive": "Kinetic theory of polydisperse granular mixtures: influence of the\n  partial temperatures on transport properties. A review: It is well-recognized that granular media under rapid flow conditions can be\nmodeled as a gas of hard spheres with inelastic collisions. At moderate\ndensities, a fundamental basis for the determination of the granular\nhydrodynamics is provided by the Enskog kinetic equation conveniently adapted\nto account for inelastic collisions. A surprising result (compared to its\nmolecular gas counterpart) for granular mixtures is the failure of the energy\nequipartition, even in homogeneous states. This means that the partial\ntemperatures $T_i$ (measuring the mean kinetic energy of each species) are\ndifferent to the (total) granular temperature $T$. The goal of this paper is to\nprovide an overview on the effect of different partial temperatures on the\ntransport properties of the mixture. Our analysis addresses first the impact of\nenergy nonequipartition on transport which is only due to the inelastic\ncharacter of collisions. This effect (which is absent for elastic collisions)\nis shown to be significant in important problems in granular mixtures such as\nthermal diffusion segregation. Then, an independent source of energy\nnonequipartition due to the existence of a divergence of the flow velocity is\nstudied. This effect (which was already analyzed in several pioneering works on\ndense hard-sphere molecular mixtures) affects to the bulk viscosity\ncoefficient. Analytical (approximate) results are compared against Monte Carlo\nand molecular dynamics simulations, showing the reliability of kinetic theory\nfor describing granular flows."
    },
    {
        "anchor": "Observation of Flux Reversal in a Symmetric Optical Thermal Ratchet: We demonstrate that a cycle of three holographic optical trapping patterns\ncan implement a thermal ratchet for diffusing colloidal spheres, and that the\nratchet-driven transport displays flux reversal as a function of the cycle\nfrequency and the inter-trap separation. Unlike previously described ratchet\nmodels, the approach we describe involves three equivalent states, each of\nwhich is locally and globally spatially symmetric, with spatiotemporal symmetry\nbeing broken by the sequence of states.",
        "positive": "Dynamical Landau-de Gennes Theory for Electrically-Responsive Liquid\n  Crystal Networks: Liquid crystal networks combine the orientational order of liquid crystals\nwith the elastic properties of polymer networks, leading to a vast application\npotential in the field of responsive coatings, e.g., for haptic feedback,\nself-cleaning surfaces and static and dynamic pattern formation. Recent\nexperimental work has further paved the way toward such applications by\nrealizing the fast and reversible surface modulation of a liquid crystal\nnetwork coating upon in-plane actuation with an AC electric field. Here, we\nconstruct a Landau-type theory for electrically-responsive liquid crystal\nnetworks and perform Molecular Dynamics simulations to explain the findings of\nthese experiments and inform on rational design strategies. Qualitatively, the\ntheory agrees with our simulations and reproduces the salient experimental\nfeatures. We also provide a set of testable predictions: the aspect ratio of\nthe nematogens, their initial orientational order when cross-linked into the\npolymer network and the cross-linking fraction of the network all increase the\nplasticization time required for the film to macroscopically deform. We\ndemonstrate that the dynamic response to oscillating electric fields is\ncharacterized by two resonances, which can likewise be influenced by varying\nthese parameters, providing an experimental handle to fine-tune device design."
    },
    {
        "anchor": "Evolution of avalanche conducting states in electrorheological liquids: Charge transport in electrorheological fluids is studied experimentally under\nstrongly nonequlibrium conditions. By injecting an electrical current into a\nsuspension of conducting nanoparticles we are able to initiate a process of\nself-organization which leads, in certain cases, to formation of a stable\npattern which consists of continuous conducting chains of particles. The\nevolution of the dissipative state in such system is a complex process. It\nstarts as an avalanche process characterized by nucleation, growth, and thermal\ndestruction of such dissipative elements as continuous conducting chains of\nparticles as well as electroconvective vortices. A power-law distribution of\navalanche sizes and durations, observed at this stage of the evolution,\nindicates that the system is in a self-organized critical state. A sharp\ntransition into an avalanche-free state with a stable pattern of conducting\nchains is observed when the power dissipated in the fluid reaches its maximum.\nWe propose a simple evolution model which obeys the maximum power condition and\nalso shows a power-law distribution of the avalanche sizes.",
        "positive": "Bose-Einstein Condensates in Magnetic Waveguides: In this article, we describe an experimental system for generating\nBose-Einstein condensates and controlling the shape and motion of the\ncondensate by using miniaturised magnetic potentials. In particular, we\ndescribe the magnetic trap setup, the vacuum system, the use of dispenser\nsources for loading a high number of atoms into the magneto-optical trap, the\nmagnetic transfer of atoms into the microtrap, and the experimental cycle for\ngenerating Bose-Einstein condensates. We present first results on outcoupling\nof condensates into a magnetic waveguide and discuss influences of the trap\nsurface on the ultracold ensembles."
    },
    {
        "anchor": "Dynamics of hydrodynamically coupled Brownian harmonic oscillators in a\n  Maxwell fluid: Recently, many interesting features of the hydrodynamically coupled motions\nof the Brownian particles in a viscous fluid have been reported which are\nimpossible for the uncoupled motions of the similar particles. However, it is\nexpected that those physics in a viscoelastic fluid is much more interesting\ndue to the presence of the additional frequency dependent elasticity of the\nmedium. Thus, a theory describing the equilibrium dynamics of two\nhydrodynamically coupled Brownian harmonic oscillators in a viscoelastic\nMaxwell fluid has been derived which appears with new and impressive aspects.\nInitially, the response functions have been calculated and then the\nfluctuation-dissipation theorem has been used to calculate the correlation\nfunctions between the coloured noises present on the concerned particles placed\nin a Maxwell fluid due to the thermal motions of the fluid molecules. These\ncorrelation functions appear to be in a linear relationship with the\ndelta-correlated noises in a viscous fluid. Consequently, this reduces the\nstatistical description of a simple viscoelastic fluid to the statistical\nrepresentation for an extended dynamical system subjected to delta-correlated\nrandom forces. Thereupon, the auto and cross-correlation functions in the time\ndomain and frequency domain and the mean-square displacement functions of the\nparticles have been calculated which are perfectly consistent with their\ncorresponding established forms in a viscous fluid and emerge with exceptional\ncharacteristics.",
        "positive": "Ordering of hard rectangles in strong confinement: Using transfer operator and fundamental measure theories, we examine the\nstructural and thermodynamic properties of hard rectangles confined between two\nparallel hard walls. The side lengths of the rectangle ($L$ and $D$, $L>D$) and\nthe pore width ($H$) are chosen such that maximum two layers are allowed to\nform in planar order ($L$ is parallel to the wall), while only one in\nhomeotropic order ($D$ is parallel to the wall). We observe three different\nstructures: (i) a low density fluid phase with parallel alignment to the wall,\n(ii) an intermediate and high density fluid phase with two layers and planar\nordering and (iii) a dense single fluid layer with homeotropic ordering. The\nappearance of these phases and the change in the ordering direction with\ndensity is a consequence of the varying close packing structures with $L$ and\n$H$. Interestingly, even three different structures can be observed with\nincreasing density if $L$ is close to $H$."
    },
    {
        "anchor": "A microscopic field theoretical approach for binary mixtures of active\n  and passive particles: We consider a phase field crystal modeling approach for binary mixtures of\ninteracting active and passive particles. The approach allows to describe\ngeneric properties for such systems within a continuum model. We validate the\napproach by reproducing experimental results, as well as results obtained with\nagent-based simulations, for the whole spectrum from highly dilute suspensions\nof passive particles to interacting active particles in a dense background of\npassive particles.",
        "positive": "Colloids in active fluids: Anomalous micro-rheology and negative drag: We simulate an experiment in which a colloidal probe is pulled through an\nactive nematic fluid. We find that the drag on the particle is non-Stokesian\n(not proportional to its radius). Strikingly, a large enough particle in\ncontractile fluid (such as an actomyosin gel) can show negative viscous drag in\nsteady state: the particle moves in the opposite direction to the externally\napplied force. We explain this, and the qualitative trends seen in our\nsimulations, in terms of the disruption of orientational order around the probe\nparticle and the resulting modifications to the active stress."
    },
    {
        "anchor": "A shape-driven reentrant jamming transition in confluent monolayers of\n  synthetic cell-mimics: Many critical biological processes, like wound healing, require confluent\ncell monolayers/bulk tissues to transition from a jammed solid-like to a\nfluid-like state. Although numerical studies anticipate changes in the cell\nshape alone can lead to unjamming, experimental support for this prediction is\nnot definitive because, in living systems, fluidization due to density changes\ncannot be ruled out. Additionally, a cell's ability to modulate its motility\nonly compounds difficulties since even in assemblies of rigid active particles,\nchanging the nature of self-propulsion has non-trivial effects on the dynamics.\nHere, we design and assemble a monolayer of synthetic cell-mimics and examine\ntheir collective behaviour. By systematically increasing the persistence time\nof self-propulsion, we discovered a cell shape-driven, density-independent,\nre-entrant jamming transition. Notably, we observed cell shape and shape\nvariability were mutually constrained in the confluent limit and followed the\nsame universal scaling as that observed in confluent epithelia. Dynamical\nheterogeneities, however, did not conform to this scaling, with the fast cells\nshowing suppressed shape variability, which our simulations revealed is due to\na transient confinement effect of these cells by their slower neighbors. Our\nexperiments unequivocally establish a morphodynamic link, demonstrating that\ngeometric constraints alone can dictate epithelial jamming/unjamming.",
        "positive": "From compact to fractal crystalline clusters in concentrated systems of\n  monodisperse hard spheres: We address the crystallization of monodisperse hard spheres in terms of the\nproperties of finite- size crystalline clusters. By means of large scale\nevent-driven Molecular Dynamics simulations, we study systems at different\npacking fractions {\\phi} ranging from weakly supersaturated state points to\nglassy ones, covering different nucleation regimes. We find that such regimes\nalso result in different properties of the crystalline clusters: compact\nclusters are formed in the classical-nucleation-theory regime ({\\phi} \\leq\n0.54), while a crossover to fractal, ramified clusters is encountered upon\nincreasing packing fraction ({\\phi} \\geq 0.56), where nucleation is more\nspinodal-like. We draw an analogy between macroscopic crystallization of our\nclusters and percolation of attractive systems to provide ideas on how the\npacking fraction influences the final structure of the macroscopic crystals. In\nour previous work (Phys. Rev. Lett., 106, 215701, 2011), we have demonstrated\nhow crystallization from a glass (at {\\phi} > 0.58) happens via a gradual\n(many-step) mechanism: in this paper we show how the mechanism of gradual\ngrowth seems to hold also in super-saturated systems just above freezing\nshowing that static properties of clusters are not much affected by dynamics."
    },
    {
        "anchor": "Entropy-induced smectic phases in rod-coil copolymers: We present a self-consistent field theory (SCFT) of semiflexible (wormlike)\ndiblock copolymers, each consisting of a rigid and a flexible part. The\nsegments of the polymers are otherwise identical, in particular with regard to\ntheir interactions, which are taken to be of an Onsager excluded-volume type.\nThe theory is developed in a general three-dimensional form, as well as in a\nsimpler one-dimensional version. Using the latter, we demonstrate that the\ntheory predicts the formation of a partial-bilayer smectic-A phase in this\nsystem, as shown by profiles of the local density and orientational\ndistribution functions. The phase diagram of the system, which includes the\nisotropic and nematic phases, is obtained in terms of the mean density and\nrigid-rod fraction of each molecule. The nematic-smectic transition is found to\nbe second order. Since the smectic phase is induced solely by the difference in\nthe rigidities, the onset of smectic ordering is shown to be an entropic effect\nand therefore does not have to rely on additional Flory-Huggins-type repulsive\ninteractions between unlike chain segments. These findings are compared with\nother recent SCFT studies of similar copolymer models and with computer\nsimulations of several molecular models.",
        "positive": "Three-dimensional patchy lattice model for empty fluids: The phase diagram of a simple model with two patches of type A and ten\npatches of type B (2A10B) on the face centred cubic lattice has been calculated\nby simulations and theory. Assuming that there is no interaction between the B\npatches the behavior of the system can be described in terms of the ratio of\nthe AB and AA interactions, r. Our results show that, similarly to what happens\nfor related off-lattice and two-dimensional lattice models, the liquid-vapor\nphase equilibria exhibits reentrant behavior for some values of the interaction\nparameters. However, for the model studied here the liquid-vapor phase\nequilibria occurs for values of r lower than 1/3, a threshold value which was\npreviously thought to be universal for 2AnB models. In addition, the theory\npredicts that below r = 1/3 (and above a new condensation threshold which is <\n1/3) the reentrant liquid-vapor equilibria is so extreme that it exhibits a\nclosed loop with a lower critical point, a very unusual behavior in\nsingle-component systems. An order-disorder transition is also observed at\nhigher densities than the liquid-vapor equilibria, which shows that the\nliquid-vapor reentrancy occurs in an equilibrium region of the phase diagram.\nThese findings may have implications in the understanding of the condensation\nof dipolar hard spheres given the analogy between that system and the 2AnB\nmodels considered here."
    },
    {
        "anchor": "Configurational entropy of polar glass formers and the effect of\n  electric field on glass transition: A model of low-temperature polar liquids is constructed that accounts for\nconfigurational heat capacity, entropy, and the effect of a strong electric\nfield on the glass transition. The model is based on Pad{\\'e}-truncated\nperturbation expansions of the liquid state theory. Depending on parameters, it\naccommodates an ideal glass transition of vanishing configurational entropy and\nits avoidance, with a square-root divergent enumeration function at the point\nof its termination. A composite density-temperature parameter $\\rho^\\gamma/T$,\noften used to represent combined pressure and temperature data, follows from\nthe model. The theory is in good agreement with experimental data for excess\n(over the crystal state) thermodynamics of molecular glass formers. We suggest\nthat the Kauzmann entropy crisis might be a signature of vanishing\nconfigurational entropy of a subset of degrees of freedom, multipolar rotations\nin our model. This scenario has observable consequences: (i) a dynamical\ncross-over of the relaxation time and (ii) the fragility index defined by the\nratio of the excess heat capacity and excess entropy at the glass transition.\nThe Kauzmann temperature of vanishing configurational entropy, and the\ncorresponding glass transition temperature, shift upward when the electric\nfield is applied. The temperature shift scales quadratically with the field\nstrength.",
        "positive": "Controlling capillary fingering using pore size gradients in disordered\n  media: Capillary fingering is a displacement process that can occur when a\nnon-wetting fluid displaces a wetting fluid from a homogeneous disordered\nporous medium. Here, we investigate how this process is influenced by a pore\nsize gradient. Using microfluidic experiments and computational pore-network\nmodels, we show that the non-wetting fluid displacement behavior depends\nsensitively on the direction and the magnitude of the gradient. The fluid\ndisplacement depends on the competition between a pore size gradient and\npore-scale disorder; indeed, a sufficiently large gradient can completely\nsuppress capillary fingering. By analyzing capillary forces at the pore scale,\nwe identify a non-dimensional parameter that describes the physics underlying\nthese diverse flow behaviors. Our results thus expand the understanding of flow\nin complex porous media, and suggest a new way to control flow behavior via the\nintroduction of pore size gradients."
    },
    {
        "anchor": "Intramolecular long-range correlations in polymer melts: The segmental\n  size distribution and its moments: Presenting theoretical arguments and numerical results we demonstrate\nlong-range intrachain correlations in concentrated solutions and melts of long\nflexible polymers which cause a systematic swelling of short chain segments.\nThey can be traced back to the incompressibility of the melt leading to an\neffective repulsion $u(s) \\approx s/\\rho R^3(s) \\approx ce/\\sqrt{s}$ when\nconnecting two segments together where $s$ denotes the curvilinear length of a\nsegment, $R(s)$ its typical size, $ce \\approx 1/\\rho be^3$ the ``swelling\ncoefficient\", $be$ the effective bond length and $\\rho$ the monomer density.\nThe relative deviation of the segmental size distribution from the ideal\nGaussian chain behavior is found to be proportional to $u(s)$. The analysis of\ndifferent moments of this distribution allows for a precise determination of\nthe effective bond length $be$ and the swelling coefficient $ce$ of\nasymptotically long chains. At striking variance to the short-range decay\nsuggested by Flory's ideality hypothesis the bond-bond correlation function of\ntwo bonds separated by $s$ monomers along the chain is found to decay\nalgebraically as $1/s^{3/2}$. Effects of finite chain length are considered\nbriefly.",
        "positive": "New method of determination of the Fr\u00e9edericksz threshold based upon\n  precise fluctuation measurement: In this paper we report a new method for determining the critical threshold\nof the Fr\\'eedericksz transition driven by an electric field. It is based on\nthe measurement of the amplitude of the molecule fluctuations as a function of\nthe voltage difference applied to a planar nematic cell. The precise\nmeasurement of the director fluctuations of the liquid crystal is made possible\nby the use of a very precise and sensitive polarization interferometer. The\ngreat advantage of the method is that it does not depend on complex fits as it\nis usually done in literature."
    },
    {
        "anchor": "Cell division and death inhibit glassy behaviour of confluent tissues: We investigate the effects of cell division and apopotosis on collective\ndynamics in two-dimensional epithelial tissues. Our model includes three key\ningredients observed across many epithelia, namely cell-cell adhesion, cell\ndeath and a cell division process that depends on the surrounding environment.\nWe show a rich non-equilibrium phase diagram depending on the ratio of cell\ndeath to cell division and on the adhesion strength. For large apopotosis\nrates, cells die out and the tissue disintegrates. As the death rate decreases,\nhowever, we show, consecutively, the existence of a gas-like phase, a gel-like\nphase, and a dense confluent (tissue) phase. Most striking is the observation\nthat the tissue is self-melting through its own internal activity, ruling out\nthe existence of any glassy phase.",
        "positive": "Coupling of surface chemistry and electric double layer at TiO$_2$\n  electrochemical interfaces: Surfaces of metal oxides at working conditions are usually electrified due to\nthe acid-base chemistry. The charged interface compensated with counterions\nforms the so-called electric double layer. The coupling of surface chemistry\nand electric double layer is considered to be crucial but poorly understood\nbecause of lacking the information at the atomistic scale. Here, we used the\nlatest development in density functional theory based finite-field molecular\ndynamics simulation to investigate pH-dependence of the Helmholtz capacitance\nat electrified rutile TiO$_2$ (110)-NaCl electrolyte interfaces. It is found\nthat, due to competing forces from surface adsorption and from electric double\nlayer, water molecules have a stronger structural fluctuation at high pH and\nthis leads to a much larger capacitance. It is also seen that, interfacial\nproton transfers at low pH increase significantly the capacitance value. These\nfindings elucidate the microscopic origin for the same trend observed in\ntitration experiments."
    },
    {
        "anchor": "Knots as Topological Order Parameter For Semi-Flexible Polymers: Using a combination of the replica-exchange Monte Carlo algorithm and the\nmulticanonical method, we investigate the influence of bending stiffness on the\nconformational phases of a bead-stick homopolymer model and present the\npseudo-phase diagram for the complete range of semi-flexible polymers, from\nflexible to stiff. Although a simple model, we observe a rich variety of\nconformational phases, reminiscent of conformations observed for synthetic\npolymers or biopolymers. Changing the internal bending stiffness, the model\nexhibits different pseudo phases like bent, hairpin or toroidal. In particular,\nwe find thermodynamically stable knots and transitions into these knotted\nphases with a clear phase coexistence, but almost no change in the mean total\nenergy.",
        "positive": "Experiments in the penetration of cuboid intruders near walls into\n  granular matter: When an object penetrates into granular matter near a boundary, it\nexperiences a horizontal repulsion due to the intruder-grain-wall interaction.\nHere we show experimentally that a square cuboid intruder, released from rest\nwith no initial velocity, neara vertical wall to its left, goes through three\ndistinct kinds of motion: it first tilts clockwise, then 'slides' away from the\nwall,and finally tilts counterclockwise. This dynamic highly favors both\nrepulsion and penetration of the cuboid intruder as compared to that observed\nfrom its release farther away from the wall"
    },
    {
        "anchor": "Shear induced rigidity in athermal materials: a unified statistical\n  framework: Recent studies of athermal systems such as dry grains and dense, non-Brownian\nsuspensions have shown that shear can lead to solidification through the\nprocess of shear jamming in grains and discontinuous shear thickening in\nsuspensions. The similarities observed between these two distinct phenomena\nsuggest that the physical processes leading to shear-induced rigidity in\nathermal materials are universal. We present a non-equilibrium statistical\nmechanics model, which exhibits the phenomenology of these shear-driven\ntransitions: shear jamming and discontinuous shear thickening in different\nregions of the predicted phase diagram. Our analysis identifies the crucial\nphysical processes underlying shear-driven rigidity transitions, and clarifies\nthe distinct roles played by shearing forces and the density of grains.",
        "positive": "On the influence of device handle in single-molecule experiments: We deduce a fully analytical model to predict the artifacts of the measuring\ndevice handles in Single Molecule Force Spectroscopy experiments. As we show,\nneglecting the effects of the handle stiffness can lead to crucial\noverestimation or underestimation of the stability properties and transition\nthresholds of macromolecules."
    },
    {
        "anchor": "Line-tension effects on heterogeneous nucleation on a spherical\n  substrate and in a spherical cavity: The line-tension effects on heterogeneous nucleation are considered when a\nspherical lens-shaped nucleus is nucleated on top of a spherical substrate and\non the bottom of the wall of a spherical cavity. The effect of line tension on\nthe nucleation barrier can be separated from the usual volume term. As the\nradius of the substrate increases, the nucleation barrier decreases and\napproaches that of a flat substrate. However, as the radius of the cavity\nincreases, the nucleation barrier increases and approaches that of a flat\nsubstrate. A small spherical substrate is a less active nucleation site than a\nflat substrate, and a small spherical cavity is a more active nucleation site\nthan a flat substrate. In contrast, the line-tension effect on the nucleation\nbarrier is maximum when the radii of the nucleus and the substrate or cavity\nbecome comparable. Therefore, by tuning the size of the spherical substrate or\nspherical cavity, the effect of the line tension can be optimized. These\nresults will be useful in broad range of applications from material processing\nto understanding of global climate, where the heterogeneous nucleation plays a\nvital role.",
        "positive": "Formation of a Columnar Liquid Crystal in a Simple One-Component System\n  of Particles: We report a molecular dynamics simulation demonstrating that a columnar\nliquid crystal, commonly formed by disc-shaped molecules, can be formed by\nidentical particles interacting via a spherically symmetric potential. Upon\nisochoric cooling from a low-density isotropic liquid state the simulated\nsystem performed a weak first order phase transition which produced a liquid\ncrystal phase composed of parallel particle columns arranged in a hexagonal\npattern in the plane perpendicular to the column axis. The particles within\ncolumns formed a liquid structure and demonstrated a significant intracolumn\ndiffusion. Further cooling resulted in another first-order transition whereby\nthe column structure became periodically ordered in three dimensions\ntransforming the liquid-crystal phase into a crystal. This result is the first\nobservation of a liquid crystal formation in a simple one-component system of\nparticles. Its conceptual significance is in that it demonstrated that liquid\ncrystals that have so far only been produced in systems of anisometric\nmolecules, can also be formed by mesoscopic soft-matter and colloidal systems\nof spherical particles with appropriately tuned interatomic potential."
    },
    {
        "anchor": "Deformation and orientational order of chiral membranes with free edges: Motivated by experiments on colloidal membranes composed of chiral rod-like\nviruses, we use Monte Carlo methods to determine the phase diagram for the\nliquid crystalline order of the rods and the membrane shape. We generalize the\nLebwohl-Lasher model for a nematic with a chiral coupling to a curved surface\nwith edge tension and a resistance to bending, and include an energy cost for\ntilting of the rods relative to the local membrane normal. The membrane is\nrepresented by a triangular mesh of hard beads joined by bonds, where each bead\nis decorated by a director. The beads can move, the bonds can reconnect and the\ndirectors can rotate at each Monte Carlo step. When the cost of tilt is small,\nthe membrane tends to be flat, with the rods only twisting near the edge for\nlow chiral coupling, and remaining parallel to the normal in the interior of\nthe membrane. At high chiral coupling, the rods twist everywhere, forming a\ncholesteric state. When the cost of tilt is large, the emergence of the\ncholesteric state at high values of the chiral coupling is accompanied by the\nbending of the membrane into a saddle shape. Increasing the edge tension tends\nto flatten the membrane. These results illustrate the geometric frustration\narising from the inability of a surface normal to have twist.",
        "positive": "Cylindrical confinement of semiflexible polymers: Equilibrium states of a closed semiflexible polymer binding to a cylinder are\ndescribed. This may be either by confinement or by constriction. Closed\ncompletely bound states are labeled by two integers: the number of\noscillations, $n$, and the number of times it winds the cylinder, $p$, the\nlatter a topological invariant. We examine the behavior of these states as the\nlength of the loop is increased by evaluating the energy, the conserved axial\ntorque and the contact force. The ground state for a given $p$ is the state\nwith $n=1$; a short loop with $p=1$ is an elliptic deformation of a parallel;\nas its length increases it elongates along the cylinder axis, with two hairpin\nends. Excited states with $n\\geq2$ and $p=1$ possess $n$-fold axial symmetry.\nShort (long) loops possess energies $\\approx p E_0$ ($nE_0$), with $E_0$ the\nenergy of a circular loop with same radius as the cylinder; in long loops the\naxial torque vanishes. Confined bound excited states are initially unstable;\nhowever, above a critical length each $n$-fold state becomes stable: the folded\nhairpin cannot be unfolded. The ground state for each $p$ is also initially\nunstable with respect to deformations rotating the loop off the surface into\nthe interior. A closed planar elastic curve aligned along the cylinder axis\nmaking contact with the cylinder on its two sides is identified as the ground\nstate of a confined loop. Exterior bound states behave very differently, if\nfree to unbind, as signaled by the reversal in the sign of the contact force.\nIf $p=1$, all such states are unstable. If $p \\geq 2$, however, a topological\nobstruction to complete unbinding exists. If the loop is short, the bound state\nwith $p=2$ and $n=1$ provides a stable constriction of the cylinder, partially\nunbinding as the length is increased. This motif could be relevant to an\nunderstanding of the process of membrane fission mediated by dynamin rings."
    },
    {
        "anchor": "Anomalously Small Excitation Gaps as a Precursor of Dislocation Core\n  Superfluidity in Solid Helium-4: In the vicinity of the insulator-to-superfluid quantum phase transition in\nits core, a dislocation in a He-4 crystal supports particle-hole excitations\nwith arbitrary small gaps. These exotic analogs of Frenkel interstitial-vacancy\npairs should manifest themselves in various threshold and thermoactivation\neffects. In Worm Algorithm simulations, we reveal the presence of corresponding\nsmall gaps via anomalous thermoactivation behavior of particle number\nfluctuations, which we unambiguously associate with dislocations by\n\"visualization\" techniques. Experimentally, the related threshold and\nthermoactivation dependencies could be observed in the ultrasound absorption.",
        "positive": "Quantifying and mapping covalent bond scission during elastomer fracture: Many new soft but tough rubbery materials have been recently discovered and\nnew applications such as flexible prosthetics, stretchable electrodes or soft\nrobotics continuously emerge. Yet, a credible multi-scale quantitative picture\nof damage and fracture of these materials has still not emerged, due to our\nfundamental inability to disentangle the irreversible scission of chemical\nbonds along the fracture path from dissipation by internal molecular friction.\nHere, by coupling new fluorogenic mechanochemistry with quantitative confocal\nmicroscopy mapping, we uncover how many and where covalent bonds are broken as\nan elastomer fractures. Our measurements reveal that bond scission near the\ncrack plane can be delocalized over up to hundreds of micrometers and increase\nby a factor of 100 depending on temperature and stretch rate, pointing to an\nintricated coupling between strain rate dependent viscous dissipation and\nstrain dependent irreversible network scission. These findings paint an\nentirely novel picture of fracture in soft materials, where energy dissipated\nby covalent bond scission accounts for a much larger fraction of the total\nfracture energy than previously believed. Our results pioneer the sensitive,\nquantitative and spatially-resolved detection of bond scission to assess\nmaterial damage in a variety of soft materials and their applications."
    },
    {
        "anchor": "Orientational and induced contributions to the depolarized Rayleigh\n  spectra of liquid and supercooled ortho-terphenyl: The depolarized light scattering spectra of the glass forming liquid\northo-terphenyl have been calculated in the low frequency region using\nmolecular dynamics simulation. Realistic system's configurations are produced\nby using a recent flexible molecular model and combined with two limiting\npolarizability schemes, both of them using the dipole-induced-dipole\ncontributions at first and second order. The calculated Raman spectral shape\nare in good agreement with the experimental results in a large temperature\nrange. The analysis of the different contributions to the Raman spectra\nemphasizes that the orientational and the collision-induced (translational)\nterms lie on the same time-scale and are of comparable intensity. Moreover, the\ncross terms are always found to be an important contribution to the scattering\nintensity.",
        "positive": "Diversity of self-propulsion speeds reduces motility-induced clustering\n  in confined active matter: Self-propelled swimmers such as bacteria agglomerate into clusters as a\nresult of their persistent motion. In 1D, those clusters do not coalesce\nmacroscopically and the stationary cluster size distribution (CSD) takes an\nexponential form. We develop a minimal lattice model for active particles in\nnarrow channels to study how clustering is affected by the interplay between\nself-propulsion speed diversity and confinement. A mixture of run-and-tumble\nparticles with a distribution of self-propulsion speeds is simulated in 1D.\nParticles can swap positions at rates proportional to their relative\nself-propulsion speed. Without swapping, we find that the average cluster size\n$L_\\text{c}$ decreases with diversity and follows a non-arithmetic power mean\nof the single-component $L_\\text{c}$'s, unlike the case of tumbling-rate\ndiversity previously studied. Effectively, the mixture is thus equivalent to a\nsystem of identical particles whose self-propulsion speed is the harmonic mean\nself-propulsion speed of the mixture. With swapping, particles escape more\nquickly from clusters. As a consequence, $L_\\text{c}$ decreases with swapping\nrates and depends less strongly on diversity. We derive a dynamical equilibrium\ntheory for the CSDs of binary and fully polydisperse systems. Similarly to the\nclustering behaviour of one-component models, our qualitative results for\nmixtures are expected to be universal across active matter. Using literature\nexperimental values for the self-propulsion speed diversity of unicellular\nswimmers known as choanoflagellates, which naturally differentiate into slower\nand faster cells, we predict that the error in estimating their $L_\\text{c}$\nvia one-component models which use the conventional arithmetic mean\nself-propulsion speed is around $30\\%$."
    },
    {
        "anchor": "From shear bands to earthquakes in a model granular material with\n  contact aging: We perform molecular dynamics simulations of homogeneous athermal systems of\npoly-disperse soft discs under shear. For purely repulsive interactions between\nparticles, and under a confining external pressure, a monotonous flow curve\n(strain rate vs. stress) starting at a critical yield stress is obtained, with\ndeformation distributing uniformly in the system, on average. Then we add a\nshort range attractive contribution to the interaction potential that increases\nits intensity as particles remain in contact for a progressively longer time,\nmimicking an aging effect into the system. In this case the flow curve acquires\na reentrant behavior, namely, a region of negative slope. Within this region\nthe deformation is seen to localize in a shear band with a well defined width\nthat decreases as the global strain rate does. At very low strain rates the\nshear band becomes very thin and deformation acquires a prominent stick-slip\nbehavior. This regime can be described as the system possessing a fault in\nwhich deformation occurs with the phenomenology that characterizes earthquakes.\nIn this way the system we are analyzing connects a regime of uniform\ndeformation at large strain rates, a localized deformation regime in the form\nof shear bands at intermediate stain rates, and seismic phenomena at very low\nstrain rate. The unifying ingredient of this phenomenology is the existence of\na reentrant flow curve, originated in the aging mechanisms present in the\nmodel.",
        "positive": "Theory of melting lines: Our understanding of the three basic states of matter (solids, liquids and\ngases) is based on temperature and pressure phase diagrams with three phase\ntransition lines: solid-gas, liquid-gas and solid-liquid lines. There are\nanalytical expressions $P(T)$ for the first two lines derived on a purely\ngeneral-theoretical thermodynamic basis. In contrast, there exists no similar\nfunction for the third, melting, line (ML). Here, we develop a general\ntwo-phase theory of MLs and their analytical form. This theory predicts the\nparabolic form of the MLs for normal melting, relates the MLs to thermal and\nelastic properties of liquid and solid phases and quantitatively agrees with\nexperimental MLs in different system types. We show that the parameters of the\nML parabola are governed by fundamental physical constants. In this sense,\nparabolic MLs possess universality across different systems."
    },
    {
        "anchor": "A possible role of salt-induced intermediates in the liquid-liquid phase\n  transitions of globular protein dispersions: A probable model of the liquid-liquid (L-L) type phase transitions in\nwater-salt dispersions of native (N*, N) globular proteins in the temperature\nrange between thermal (D*) and cold (D) denaturation has been proposed. Protein\nintermediates (I, I*) arising as a result of the ion non-equilibrium\n(de)sorption in the process of D <-> N and D* <-> N* transitions are assumed to\nbe involved in the L-L micro-phase transition forming clusters and fibrils in\nthe main phase of N and N* proteins. Thus, they compensate for their excess\nchemical potential (ChPot) caused by unbalanced distribution of adsorbed salt\nions in protein structure as compared to N-protein. A temperature model is\nproposed for the behavior of ChPots (delta mui) of various states of the\nprotein: low-temperature i = D, N, I and high-temperature i = D*, N*, I*, as\nwell as the transition between them. On this basis, the temperature dependence\nof the solvent ChPot delta mu1 is proposed. The relationship between the\nextreme values of delta mu1 and the temperatures of the critical points (upper\nand lower critical solution temperatures) of L-L transitions is established.\nThe reasons for the nonideal behavior of osmotic pressure at different\ntemperatures in water-salt protein dispersions are discussed on the basis of\nthe phase diagrams.",
        "positive": "Optical manipulation of shape-morphing elastomeric liquid crystal\n  microparticles doped with gold nanocrystals: We demonstrate facile optical manipulation of shape of birefringent colloidal\nmicroparticles made from liquid crystal elastomers. Using soft lithography and\npolymerization, we fabricate elastomeric microcylinders with weakly undulating\ndirector oriented on average along their long axes. These particles are\ninfiltrated with gold nanospheres acting as heat transducers that allow for an\nefficient localized transfer of heat from a focused infrared laser beam to a\nsubmicrometer region within a microparticle. Photothermal control of ordering\nin the liquid crystal elastomer using scanned beams allows for a robust control\nof colloidal particles, enabling both reversible and irreversible changes of\nshape. Possible applications include optomechanics, microfluidics, and\nreconfigurable colloidal composites with shape-dependent self-assembly."
    },
    {
        "anchor": "Inverse Freezing in Mean-Field Models of Fragile Glasses: A disordered spin model suitable for studying inverse freezing in fragile\nglass-forming systems is introduced. The model is a microscopic realization of\nthe ``random-first order'' scenario in which the glass transition can be either\ncontinuous or discontinuous in thermodynamic sense. The phase diagram exhibits\na first-order transition line between two fluid phases terminating at a\ncritical point. When the interacting degrees of freedom are entropically\nfavoured an inverse static glass transition and a double inverse dynamic\nfreezing appear.",
        "positive": "An Analytical Approach to the Protein Designability Problem: We present an analytical method for determining the designability of protein\nstructures. We apply our method to the case of two-dimensional lattice\nstructures, and give a systematic solution for the spectrum of any structure.\nUsing this spectrum, the designability of a structure can be estimated. We\noutline a heirarchy of structures, from most to least designable, and show that\nthis heirarchy depends on the potential that is used."
    },
    {
        "anchor": "Multi-stable free states of an active particle from a coherent memory\n  dynamics: We investigate the dynamics of a deterministic self-propelled particle\nendowed with coherent memory. We evidence experimentally and numerically that\nit exhibits several stable free states. The system is composed of a\nself-propelled drop bouncing on a vibrated liquid driven by the waves it emits\nat each bounce. This object possesses a propulsion memory resulting from the\ncoherent interference of the waves accumulated along its path. We investigate\nhere the transitory regime of the build-up of the dynamics which leads to\nvelocity modulations. Experiments and numerical simulations enable us to\nexplore unchartered areas of the phase space and reveal the existence of a\nself-sustained oscillatory regime. Finally, we show the co-existence of several\nfree states. This feature emerges both from the spatio-temporal non-locality of\nthis path memory dynamics as well as the wave nature of the driving mechanism.",
        "positive": "Dynamical heterogeneity in active glasses is inherently different from\n  its equilibrium behavior: Activity-driven glassy dynamics, while ubiquitous in collective cell\nmigration, intracellular transport, dynamics in bacterial and ant colonies,\netc., also extend the scope and extent of the as-yet mysterious physics of\nglass transition. Active glasses are hitherto assumed to be qualitatively\nsimilar to their equilibrium counterparts at an effective temperature,\n$T_{eff}$. Here we combine large-scale simulations and an analytical\nmode-coupling theory (MCT) for such systems and show that, in fact, an active\nglass is inherently different from an equilibrium glass. Although the\nrelaxation dynamics can be equilibrium-like at a $T_{eff}$, the effects of\nactivity on the dynamical heterogeneity (DH), which has emerged as a\ncornerstone of glassy dynamics, are quite nontrivial and complex. With no\npreexisting data, we employ four distinct methods for reliable estimates of the\nDH length scales. Our work shows active glasses exhibit dramatic growth of DH\nand systems with similar relaxation times, and $T_{eff}$ can have widely\nvarying DH. To theoretically study DH, we extend active MCT and find excellent\nagreement between the theory and simulation results. Our results question the\nsupposedly central role of DH in glassy dynamics and can have fundamental\nsignificance even in equilibrium."
    },
    {
        "anchor": "The Phase Behaviors of A Polymer Solution Confined between Two\n  Concentric Cylinders: A theoretical study on the phase behaviors of a polymer solution confined\nbetween two coaxial cylindrical walls is presented. For the case of a neutral\ninner cylinder, the spinodal point derived through the Gaussian fluctuation\ntheory is confinement-independent because of the existence of a free dimension\nin the system. The kinetic analysis indicates that the fluctuation modes always\nhave a component of a plane wave along the axial direction, which can lead to\nthe formation of a periodic-like concentration pattern. On the other hand, the\nequilibrium structure of the system is obtained by using the self-consistent\nmean-field theory (SCMFT) and the interplay between the \"wetting\" phenomenon\nand the phase separation is observed by modifying the property of the inner\ncylinderical wall.",
        "positive": "Lateral migration of a 2D vesicle in unbounded Poiseuille flow: The migration of a suspended vesicle in an unbounded Poiseuille flow is\ninvestigated numerically in the low Reynolds number limit. We consider the\nsituation without viscosity contrast between the interior of the vesicle and\nthe exterior. Using the boundary integral method we solve the corresponding\nhydrodynamic flow equations and track explicitly the vesicle dynamics in two\ndimensions. We find that the interplay between the nonlinear character of the\nPoiseuille flow and the vesicle deformation causes a cross-streamline migration\nof vesicles towards the center of the Poiseuille flow. This is in a marked\ncontrast with a result [L.G. Leal, Ann. Rev. Fluid Mech. 12,\n435(1980)]according to which the droplet moves away from the center (provided\nthere is no viscosity contrast between the internal and the external fluids).\nThe migration velocity is found to increase with the local capillary number\n(defined by the time scale of the vesicle relaxation towards its equilibrium\nshape times the local shear rate), but reaches a plateau above a certain value\nof the capillary number. This plateau value increases with the curvature of the\nparabolic flow profile. We present scaling laws for the migration velocity."
    },
    {
        "anchor": "Fine-Tuning of Colloidal Polymer Crystals by Molecular Simulation: Through extensive molecular simulations we determine a phase diagram of\nattractive, flexible polymer chains in two and three dimensions. A surprisingly\nrich collection of distinct crystal morphologies appear, which can be finely\ntuned through the range of attraction. In three dimensions these include the\nface centered cubic, hexagonal close packed, simple hexagonal and body centered\ncubic crystals and the Frank-Kasper phase. A simple geometric model is\nproposed, based on the concept of cumulative neighbours of ideal crystals,\nwhich can accurately predict most of the observed structures and the\ncorresponding transitions. The attraction range can thus be considered as an\nadjustable parameter for the design of colloidal polymer crystals with tailored\nmorphologies.",
        "positive": "Morphology of Evaporating Sessile Microdroplets on Lyophilic Elliptical\n  Patches: The evaporation of droplets occurs in a large variety of natural and\ntechnological processes such as medical diagnostics, agriculture, food\nindustry, printing, and catalytic reactions. We study the different droplet\nmorphologies adopted by an evaporating droplet on a surface with an elliptical\npatch with a different contact angle. We perform experiments to observe these\nmorphologies and use numerical calculations to predict the effects of the\npatched surfaces. We observe that tuning the geometry of the patches offers\ncontrol over the shape of the droplet. In the experiments, the drops of various\nvolumes are placed on elliptical chemical patches of different aspect ratios\nand imaged in 3D using laser scanning confocal microscopy, extracting the\ndroplets shape. In the corresponding numerical simulations, we minimize the\ninterfacial free energy of the droplet, by employing Surface Evolver. The\nnumerical results are in good qualitative agreement with our experimental data\nand can be used for the design of micropatterned structures, potentially\nsuggesting or excluding certain morphologies for particular applications.\nHowever, the experimental results show the effects of pinning and contact angle\nhysteresis, which are obviously absent in the numerical energy minimization.\nThe work culminates with a morphology diagram in the aspect ratio vs relative\nvolume parameter space, comparing the predictions with the measurements."
    },
    {
        "anchor": "Soft nanobubbles can deform rigid glasses: Confined glasses and their anomalous interfacial rheology raise important\nquestions in fundamental research and numerous practical applications. In this\nLetter, we study the influence of interfacial air nanobubbles on the free\nsurface of ultrathin high-molecular-weight glassy polystyrene films immersed in\nwater, in ambient conditions. In particular, we reveal the counterintuitive\nfact that a soft nanobubble is able to deform the surface of a rigid glass,\nforming a nanocrater with a depth that increases with time. By combining\nin-situ atomic-force-microscopy measurements and a modified lubrication model\nfor the liquid-like layer at the free surface of the glass, we demonstrate that\nthe capillary pressure in the nanobubble together with the liquid-like layer at\nthe free surface of the glass determine the spatiotemporal growth of the\nnanocraters. Finally, from the excellent agreement between the experimental\nprofiles and the numerical solutions of the governing glassy thin-film\nequation, we are able to precisely extract the surface mobility of the glass.\nIn addition to revealing and quantifying how surface nanobubbles deform\nimmersed glasses, until the latter eventually dewet from their substrates, our\nwork provides a novel, precise, and simple measurement of the surface\nnanorheology of glasses.",
        "positive": "Efficient numerical simulation of granular matter using the\n  Bottom-To-Top Reconstruction method: The numerical simulation of granular systems of even moderate size is a\nchallenging computational problem. In most investigations, either Molecular\nDynamics or Event-driven Molecular Dynamics is applied. Here we show that in\ncertain cases, mainly (but not exclusively) for static granular packings, the\nBottom-to-top Reconstruction method allows for the efficient simulation of very\nlarge systems. We apply the method to heap formation, granular flow in a\nrotating cylinder and to structure formation in nano-powders. We also present\nan efficient implementation of the algorithm in C++, including a benchmark."
    },
    {
        "anchor": "Retention and Deformation of the Blue Phases in Liquid Crystalline\n  Elastomers: The blue phases are observed in highly chiral liquid crystalline compositions\nthat nascently organize into a three-dimensional, crystalline nanostructure.\nThe periodicity of the unit cell lattice parameters is on the order of the\nwavelength of visible light and accordingly, the blue phases exhibit a\nselective reflection as a photonic crystal. Here, we detail the synthesis of\nliquid crystalline elastomers (LCEs) that retain blue phase I, blue phase II,\nand blue phase III. The mechanical properties and deformation of LCEs retaining\nthe blue phases are contrasted to the cholesteric phase in fully solid\nelastomers with glass transition temperatures below room temperature.\nMechanical deformation and chemical swelling of the lightly crosslinked polymer\nnetworks induces lattice asymmetry in the blue phase LCE evident in the tuning\nof the selective reflection. The lattice periodicity of the blue phase LCE is\nminimally affected by temperature. The oblique lattice planes of the blue phase\nLCEs tilt and red-shift in response to mechanical deformation. The retention of\nthe blue phases in fully solid, elastomeric films could enable new functional\nimplementations in photonics, sensing, and energy applications.",
        "positive": "Packing defects and the width of biopolymer bundles: The formation of bundles composed of actin filaments and cross-linking\nproteins is an essential process in the maintenance of the cells' cytoskeleton.\nIt has also been recreated by in-vitro experiments, where actin networks are\nroutinely produced to mimic and study the cellular structures. It has long been\nobserved that these bundles seem to have a well defined width distribution,\nwhich has not been adequately described theoretically. We propose here that\npacking defects of the filaments, quenched and random, contribute an effective\nrepulsion that counters the cross-linking adhesion energy and leads to a well\ndefined bundle width. This is a two-dimensional strain-field version of the\nclassic Rayleigh instability of charged droplets."
    },
    {
        "anchor": "Energy invariance in capillary systems: We demonstrate the continuous translational invariance of the energy of a\ncapillary surface in contact with reconfigurable solid boundaries. We present a\ntheoretical approach to find the energy-invariant equilibria of spherical\ncapillary surfaces in contact with solid boundaries of arbitrary shape and\nexamine the implications of dynamic frictional forces upon a reconfiguration of\nthe boundaries. Experimentally, we realise our ideas by manipulating the\nposition of a droplet in a wedge geometry using lubricant-impregnated solid\nsurfaces, which eliminate the contact-angle hysteresis and provide a test bed\nfor quantifying dissipative losses out of equilibrium. Our experiments show\nthat dissipative energy losses for an otherwise energy-invariant\nreconfiguration are relatively small, provided that the actuation timescale is\nlonger than the typical relaxation timescale of the capillary surface. We\ndiscuss the wider applicability of our ideas as a pathway for liquid\nmanipulation at no potential energy cost in low-pinning, low-friction\nsituations.",
        "positive": "Nonlinear theory of solitary waves associated with longitudinal particle\n  motion in lattices - Application to longitudinal grain oscillations in a dust\n  crystal: The nonlinear aspects of longitudinal motion of interacting point masses in a\nlattice are revisited, with emphasis on the paradigm of charged dust grains in\na dusty plasma (DP) crystal. Different types of localized excitations,\npredicted by nonlinear wave theories, are reviewed and conditions for their\noccurrence (and characteristics) in DP crystals are discussed. Making use of a\ngeneral formulation, allowing for an arbitrary (e.g. the Debye electrostatic or\nelse) analytic potential form $\\phi(r)$ and arbitrarily long site-to-site range\nof interactions, it is shown that dust-crystals support nonlinear kink-shaped\nlocalized excitations propagating at velocities above the characteristic DP\nlattice sound speed $v_0$. Both compressive and rarefactive kink-type\nexcitations are predicted, depending on the physical parameter values, which\nrepresent pulse- (shock-)like coherent structures for the dust grain relative\ndisplacement. Furthermore, the existence of breather-type localized\noscillations, envelope-modulated wavepackets and shocks is established. The\nrelation to previous results on atomic chains as well as to experimental\nresults on strongly-coupled dust layers in gas discharge plasmas is discussed."
    },
    {
        "anchor": "On the spontaneous collective motion of active matter: Spontaneous directed motion, a hallmark of cell biology, is unusual in\nclassical statistical physics. Here we study, using both numerical and\nanalytical methods, organized motion in models of the cytoskeleton in which\nconstituents are driven by energy-consuming motors. While systems driven by\nsmall-step motors are described by an effective temperature and are thus\nquiescent, at higher order in step size, both homogeneous and inhomogeneous,\nflowing and oscillating behavior emerges. Motors that respond with a negative\nsusceptibility to imposed forces lead to an apparent negative-temperature\nsystem in which beautiful structures form resembling the asters seen in cell\ndivision.",
        "positive": "A surface-renewal model for constant flux cross-flow microfiltration: A mathematical model using classical cake-filtration theory and the\nsurface-renewal concept is formulated for describing constant flux, cross-flow\nmicrofiltration (CFMF). The model provides explicit analytical expressions for\nthe transmembrane pressure drop (TMP) and cake-mass buildup on the membrane\nsurface as a function of filtration time. The basic parameters of the model are\nthe membrane resistance, specific cake resistance, and rate of surface renewal.\nThe surface-renewal model has two forms: the complete model, which holds for\ncompressible cakes, and a subsidiary model for incompressible cakes, which can\nbe derived from the complete model. The subsidiary model is correlated against\nsome of the experimental TMP data reported by Miller et al. (2014) for constant\nflux CFMF of a soybean-oil emulsion in a cross-flow filtration cell having\nunmodified and surface-modified, fouling-resistant membranes, and has an\naverage root-mean-square (RMS) error of 6.2%. The complete model is fitted to\nthe experimental TMP data reported by Ho and Zydney (2002) for constant flux\nmicrofiltration of a bovine serum albumin solution in a stirred cell using\npolycarbonate track-etched membranes and has an average RMS error of 11.2%.\nThis model is also correlated against the TMP data of Kovalsky et al. (2009)\nfor constant flux yeast filtration in a stirred cell (average RMS error =\n9.2%)."
    },
    {
        "anchor": "Density profiles and surface tensions of polymers near colloidal\n  surfaces: The surface tension of interacting polymers in a good solvent is calculated\ntheoretically and by computer simulations for a planar wall geometry and for\nthe insertion of a single colloidal hard-sphere. This is achieved for the\nplanar wall and for the larger spheres by an adsorption method, and for smaller\nspheres by a direct insertion technique. Results for the dilute and semi-dilute\nregimes are compared to results for ideal polymers, the Asakura-Oosawa\npenetrable-sphere model, and to integral equations, scaling and renormalization\ngroup theories. The largest relative changes with density are found in the\ndilute regime, so that theories based on non-interacting polymers rapidly break\ndown. A recently developed ``soft colloid'' approach to polymer-colloid\nmixtures is shown to correctly describe the one-body insertion free-energy and\nthe related surface tension.",
        "positive": "Copolymer adsorption kinetics at a selective liquid-liquid interface:\n  Scaling theory and computer experiment: We consider the adsorption kinetics of a regular block-copolymer of total\nlength $N$ and block size $M$ at a selective liquid-liquid interface in the\nlimit of strong localization. We propose a simple analytic theory based on\nscaling considerations which describes the relaxation of the initial coil into\na flat-shaped layer. The characteristic times for attaining equilibrium values\nof the gyration radius components perpendicular and parallel to the interface\nare predicted to scale with chain length $N$ and block length $M$ as\n$\\tau_{\\perp} \\propto M^{1+2\\nu}$ (here $\\nu\\approx 0.6$ is the Flory exponent)\nand as $\\tau_{\\parallel} \\propto N^2$, although initially the rate of coil\nflattening is expected to decrease with block size as $\\propto M^{-1}$. Since\ntypically $N\\gg M$ for multiblock copolymers, our results suggest that the\nflattening dynamics proceeds faster perpendicular rather than parallel to the\ninterface. We also demonstrate that these scaling predictions agree well with\nthe results of extensive Monte Carlo simulations of the localization dynamics."
    },
    {
        "anchor": "Membrane viscosity signature in thermal undulations of curved fluid\n  bilayers: Membrane viscosity is usually assumed to only affect short-wavelength\nundulations of lipid bilayers. Here, we show that fluctuation dynamics about a\ncurved shape such as a quasi-spherical vesicle is sensitive to the membrane\nviscosity even at long wavelengths, if the Saffman-Debr\\\"uck length is larger\nthan the radius of curvature. The theory predicts a relaxation rate of $\\sim\n\\ell^4$ for a spherical harmonic mode $\\ell$, a drastic change from the classic\nresult $\\sim \\ell^3$. Accordingly, the anomalous diffusion exponent governing\nthe Dynamic Structure Factor (DSF) becomes 1/2 instead of the commonly used 2/3\n[Zilman and Granek, Phys. Rev. Lett. (1996)]. Flickering spectroscopy of the\nshape fluctuations of giant vesicles made of phospholipid/cholesterol mixtures\nconfirm the theoretical results and, for the first time, demonstrate the effect\nof membrane viscosity in the bilayer thermal undulations. The new DSF scaling\nimplies that the data analysis in methods that utilize DSF of liposomes, e.g.,\nneutron spin echo, need to be reassessed.",
        "positive": "Learned multi-stability in mechanical networks: We contrast the distinct frameworks of materials design and physical learning\nin creating elastic networks with desired stable states. In design, the desired\nstates are specified in advance and material parameters can be optimized on a\ncomputer with this knowledge. In learning, the material physically experiences\nthe desired stable states in sequence, changing the material so as to stabilize\neach additional state. We show that while designed states are stable in\nnetworks of linear Hookean springs, sequential learning requires specific\nnon-linear elasticity. We find that such non-linearity stabilizes states in\nwhich strain is zero in some springs and large in others, thus playing the role\nof Bayesian priors used in sparse statistical regression. Our model shows how\nspecific material properties allow continuous learning of new functions through\ndeployment of the material itself."
    },
    {
        "anchor": "Curvature-mediated Programming of Liquid Crystal Microflows: Using experiments and numerical simulations, we demonstrate that the\ncurvature of microscale conduits allow programming of liquid crystal (LC)\nflows. Focusing on a nematic LC flowing through U- and L-shaped channels of\nrectangular cross-section, our results reveal that curved flow paths can\ntrigger gradients of flow-induced director field in the transverse direction.\nThe emergent director field feeds back into the flow field, ultimately leading\nto LC flows controlled by the channel curvature. This curvature-mediated flow\ncontrol, identified by polarizing optical microscopy and supported by the\nnematofluidic solutions, offers novel concepts in LC-based microfluidic valves\nand throttles, wherein the throughput distribution is determined by the\nEricksen number and the variations in the local curvature. Finally, this work\nhighlights the role of deformation history on flow-induced director alignments,\nwhen the viscous and elastic effects comparable in strength.",
        "positive": "Temperature Dependent Heterogeneous Rotational Correlation in Lipids: Lipid structures exhibit complex and highly dynamic lateral structure; and\nchanges in lipid density and fluidity are believed to play an essential role in\nmembrane targeting and function. The dynamic structure of liquids on the\nmolecular scale can exhibit complex transient density fluctuations. Here the\nlateral heterogeneity of lipid dynamics is explored in free standing lipid\nmonolayers. As the temperature is lowered the probes exhibit increasingly broad\nand heterogeneous rotational correlation. This increase in heterogeneity\nappears to exhibit a critical onset, similar to those observed for glass\nforming fluids. We explore heterogeneous relaxation in in a single constituent\nlipid monolayer of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) by\nmeasuring the rotational diffusion of a fluorescent probe,\n1-palmitoyl-2-[1]-sn-glycero-3-phosphocholine (NBD-PC), using wide-field\ntime-resolved fluorescence anisotropy (TRFA). The observed relaxation exhibits\na narrow, liquid-like distribution at high temperatures ({\\tau} ~ 2.4 ns),\nconsistent with previous experimental measures [1, 2]. However, as the\ntemperature is quenched, the distribution broadens, and we observe the\nappearance of a long relaxation population ({\\tau} ~ 16.5 ns). This supports\nthe heterogeneity observed for lipids at high packing densities, and\ndemonstrates that the nanoscale diffusion and reorganization in lipid\nstructures can be significantly complex, even in the simplest amorphous\narchitectures. Dynamical heterogeneity of this form can have a significant\nimpact on the organization, permeability and energetics of lipid membrane\nstructures."
    },
    {
        "anchor": "The nonlinear elasticity of an $\u03b1$-helical polypeptide: Monte Carlo\n  studies: We perform Monte Carlo simulations to study the elastic properties of the\nhelix-coil worm-like chain model of alpha-helical polypeptides. In this model\nthe secondary structure enters as a scalar (Ising like) variable that controls\nthe local chain bending modulus. We compute numerically the bending and\nstretching compliances of this molecule as well as the nonlinear interaction\nbetween stretching and torque over a wide range of model parameters. The\nnumerical results agree well with previous mean-field and perturbative\ncalculations where they are expected to do so. The Monte Carlo simulations\nallow us to examine the response of the chain to large forces and torques where\nthe perturbative approaches fail. In addition we extend our mean-field analysis\nby studying the fluctuation dominated regime at the force-induced denaturation\ntransition.",
        "positive": "Orientational relaxation in a dispersive dynamic medium : Generalization\n  of the Kubo-Ivanov-Anderson jump diffusion model to include fractional\n  environmental dynamics: Ivanov-Anderson (IA) model (and an earlier treatment by Kubo) envisages a\ndecay of the orientational correlation by random but large amplitude molecular\njumps, as opposed to infinitesimal small jumps assumed in Brownian diffusion.\nRecent computer simulation studies on water and supercooled liquids have shown\nthat large amplitude motions may indeed be more of a rule than exception.\nExisting theoretical studies on jump diffusion mostly assume an exponential\n(Poissonian) waiting time distribution for jumps, thereby again leading to an\nexponential decay. Here we extend the existing formalism of Ivanov and Anderson\nto include an algebraic waiting time distribution between two jumps. As a\nresult, the first and second rank orientational time correlation functions show\nthe same long time power law, but their short time decay behavior is quite\ndifferent. The predicted Cole-Cole plot of dielectric relaxation reproduces\nvarious features of non-Debye behaviour observed experimentally. We also\ndeveloped a theory where both unrestricted small jumps and large angular jumps\ncoexist simultaneously. The small jumps are shown to have a large effect on the\nlong time decay, particularly in mitigating the effects of algebraic waiting\ntime distribution, and in giving rise to an exponential-like decay, with a time\nconstant, surprisingly, less than the time constant that arises from small\namplitude decay alone."
    },
    {
        "anchor": "Mean-field model for the interference of matter waves from a\n  three-dimensional optical trap: Using the mean-field time-dependent Gross-Pitaevskii equation we study the\nformation of a repulsive Bose-Einstein condensate on a combined optical and\nharmonic traps in two and three dimensions and subsequent generation of the\ninterference pattern upon the removal of the combined traps as in the\nexperiment by Greiner {\\it et al.} [Nature (London) {\\bf 415}, 39 (2002)]. For\noptical traps of moderate strength, interference pattern of 27 (9) prominent\nbright spots is found to be formed in three (two) dimensions on a cubic\n(square) lattice in agreement with experiment. Similar interference pattern can\nalso be formed upon removal of the optical lattice trap only. The pattern so\nformed can oscillate for a long time in the harmonic trap which can be observed\nexperimentally.",
        "positive": "Adsorption-like Collapse of Diblock Copolymers: A linear copolymer made of two reciprocally attracting N-monomer blocks\ncollapses to a compact phase through a novel transition, whose exponents are\ndetermined with extensive MC simulations in two and three dimensions. In the\nformer case, an identification with the statistical geometry of suitable\npercolation paths allows to predict that the number of contacts between the\nblocks grows like $N^{9/16}$. In the compact phase the blocks are mixed and, in\ntwo dimensions, also zipped, in such a way to form a spiral, double chain\nstructure."
    },
    {
        "anchor": "On gyration radius distributions of star-like macromolecules: Using the path integral approach, we obtain the characteristic functions of\nthe gyration radius distributions for Gaussian star and Gaussian rosette\nmacromolecules. We derive the analytical expressions for cumulants of the both\ndistributions. Applying the steepest descent method, we estimate the\nprobability distribution functions of the gyration radius in the limit of a\nlarge number of star and rosette arms in two limiting regimes: for strongly\nexpanded and strongly collapsed macromolecules. We show that in both cases, in\nthe regime of a large gyration radius relative to its mean-square value, the\nprobability distribution functions can be described by the Gaussian functions.\nIn the shrunk macromolecule regime, both distribution functions tend to zero\nfaster than any power of the gyration radius. Based on the asymptotic behavior\nof the distribution functions and the behavior of statistical dispersions, we\ndemonstrate that the probability distribution function for the rosette is more\ndensely localized near its maximum than that for the star polymer. We construct\nthe interpolation formula for the gyration radius distribution for the Gaussian\nstar macromolecule which can help to take into account the conformational\nentropy of the flexible star macromolecules within the Flory-type mean-field\ntheories",
        "positive": "Tunable wave propagation by varying prestrain in tensegrity-based\n  periodic media: This paper investigates the dynamic properties of one, two and\nthree-dimensional tensegrity-based periodic structures introduced in Rimoli and\nPal, Comp. B, 2017, which are here termed as tensegrity beams, plates and\nsolids, respectively. We study their linear wave propagation properties and\nshow that in each case, these properties can be significantly altered by the\nprestrain in the cables. As the prestrain is varied, we observe jumps in the\nwave velocities at two critical prestrain values, which define transitions\nbetween the three distinct phases of these structural assemblies. At low cable\nprestrains, the wave speeds are zero as the lattices have zero effective\nstiffness. At moderate prestrains, the wave speed is nonzero and finally, at\nprestrain levels where the bars buckle, the wave speed decreases to a lower\nvalue. Dispersion analysis on these beams, plates and solids reveal unique\nproperties such as very low wave velocities compared to their constituent\nmaterial and the existence of flat bands at low frequencies. Furthermore, we\nfind that shear waves travel faster than longitudinal waves in tensegrity\nsolids in a range of cable prestrains. Finally, we verify the key observations\nthrough detailed numerical simulations on finite tensegrity solids."
    },
    {
        "anchor": "Molecular rotors to probe the local viscosity of a polymer glass: We investigate the local viscosity of a polymer glass around its glass\ntransition temperature using environment-sensitive fluorescent molecular rotors\nembedded in the polymer matrix. The rotors' fluorescence depends on the local\nviscosity, and measuring the fluorescence intensity and lifetime of the probe\ntherefore allows to measure the local free volume in the polymer glass when\ngoing through the glass transition. This also allows us to study the local\nviscosity and free volume when the polymer film is put under an external\nstress. We find that the film does not flow homogeneously, but undergoes shear\nbanding that is visible as a spatially varying free volume and viscosity.",
        "positive": "Continuous melting through a hexatic phase in confined bilayer water: Liquid water is not only of obvious importance but also extremely intriguing,\ndisplaying many anomalies that still challenge our understanding of such an a\npriori simple system. The same is true when looking at nanoconfined water: The\nliquid between constituents in a cell is confined to such dimensions, and there\nis already evidence that such water can behave very differently from its bulk\ncounterpart. A striking finding has been reported from computer simulations for\ntwo-dimensionally confined water: The liquid displays continuous or\ndiscontinuous melting depending on its density. In order to understand this\nbehavior, we have analyzed the melting exhibited by a bilayer of nanoconfined\nwater by means of molecular dynamics simulations. At high density we observe\nthe continuous melting to be related to the phase change of the oxygens only,\nwith the hydrogens remaining liquid-like throughout. Moreover, we find an\nintermediate hexatic phase for the oxygens between the liquid and a triangular\nsolid ice phase, following the Kosterlitz-Thouless-Halperin-Nelson-Young theory\nfor two-dimensional melting. The liquid itself tends to maintain the local\nstructure of the triangular ice, with its two layers being strongly correlated,\nyet with very slow exchange of matter. The decoupling in the behavior of the\noxygens and hydrogens gives rise to a regime in which the complexity of water\nseems to disappear, resulting in what resembles a simple monoatomic liquid.\nThis intrinsic tendency of our simulated water may be useful for understanding\nnovel behaviors in other confined and interfacial water systems."
    },
    {
        "anchor": "Omnidirectional Transport in Fully Reconfigurable Two Dimensional\n  Optical Ratchets: A fully reconfigurable two-dimensional (2D) rocking ratchet system created\nwith holographic optical micromanipulation is presented. We can generate\noptical potentials with the geometry of any Bravais lattice in 2D and introduce\na spatial asymmetry with arbitrary orientation. Nontrivial directed transport\nof Brownian particles along different directions is demonstrated numerically\nand experimentally, including on-axis, perpendicular and oblique with respect\nto an unbiased ac driving. The most important aspect to define the current\ndirection is shown to be the asymmetry and not the driving orientation, and yet\nwe show a system in which the asymmetry orientation of each potential well does\nnot coincide with the transport direction, suggesting an additional symmetry\nbreaking as a result of a coupling with the lattice configuration. Our\nexperimental device, due to its versatility, opens up a new range of\npossibilities in the study of nonequilibrium dynamics at the microscopic level.",
        "positive": "Aging, Fragility and Reversibility Window in Bulk Alloy Glasses: Non-reversing relaxation enthalpies (DHnr) at glass transitions Tg(x) in the\nPxGexSe1-2x ternary display wide, sharp and deep global minima (~ 0) in the\n0.09 < x < 0.145 range, within which Tgs become thermally reversing. In this\nreversibility window, glasses are found not to age, in contrast to aging\nobserved for fragile glass compositions outside the window. Thermal\nreversibility and lack of aging seem to be paradigms of self-organization which\nmolecular glasses share with protein structures which repetitively and\nreversibly change conformation near Tg and the folding temperature\nrespectively."
    },
    {
        "anchor": "The interplay between thermodynamics and kinetics in the self-assembly\n  of DNA functionalized nanoparticles: We use a coarse-grained model of DNA-functionalized particles to understand\nthe role of DNA chain length on their self-assembly. We find that the\nincreasing chain length for a given particle size decreases the propensity to\nform ordered crystalline assemblies, and instead, disordered structures start\nto form when the chain length exceeds a certain threshold, which is consistent\nwith the previous experiments. Further analysis of the simulation data suggests\nweakening interparticle interactions with increasing chain length, thereby\nshifting the suitable assembly conditions to lower temperatures at which\nassembly dynamics are unfavorable. This highlights a complex interplay between\nthermodynamics and dynamics, which we suggest can be modulated by changing the\nsystem parameters such as DNA grafting density, resulting in successful\ncrystallization of particles with longer DNA chain lengths. Our results\nhighlight the power of computational modeling in elucidating the fundamental\ndesign principles and guiding the assembly of nanoparticles to form complex\nnanostructures.",
        "positive": "Weak Interactions in Dimethyl Sulfoxide (DMSO) -- Tertiary Amide\n  Solutions: the Versatility of DMSO as a Solvent: The structures of equimolar mixtures of the commonly used polar aprotic\nsolvents dimethylformamide (DMF) and dimethylacetamide (DMAc) in\ndimethylsulfoxide (DMSO) have been investigated via neutron diffraction\naugmented by extensive hydrogen/deuterium isotopic substitution. Detailed\n3-dimensional structural models of these solutions have been derived from the\nneutron data via Empirical Potential Structure Refinement (EPSR).The\nintermolecular Centre-of-Mass (CoM) distributions show that the first\ncoordination shell of the amides comprises 13-14 neighbours, of which\napproximately half are DMSO. In spite of this near ideal coordination shell\nmixing, the changes to the amide-amide structure are found to be relatively\nsubtle when compared to the pure liquids. Analysis of specific intermolecular\natom-atom correlations allows quantitative interpretation of the competition\nbetween weak interactions in solution. We find a hierarchy of formic and methyl\nC-H to O hydrogen bonds form the dominant local motifs, with peak positions in\nthe range 2.5-3.0 {\\AA}. We also observe a rich variety of steric and\ndispersion interactions, including those involving the amide pi-backbones. This\ndetailed insight into the structural landscape of these important liquids\ndemonstrates the versatility of DMSO as a solvent and the unparalleled\nresolution of neutron diffraction, which is critical for understanding weak\nintermolecular interactions at the nanoscale and thereby tailoring solvent\nproperties to specific applications."
    },
    {
        "anchor": "Reversible and Irreversible Aggregation of Magnetic Liposomes: Understanding stabilization and aggregation in magnetic nanoparticle systems\nis crucial to optimizing the functionality of these systems in real\nphysiological applications. Here we address this problem for a specific, yet\nrepresentative, system. We present an experimental and analytical study on the\naggregation of superparamagnetic liposomes in suspension in the presence of a\ncontrollable external magnetic field. We study the aggregation kinetics and\nreport an intermediate time power law evolution and a long time stationary\nvalue for the average aggregate diffusion coefficient, both depending on the\nmagnetic field intensity. We then show that the long time aggregate structure\nis fractal with a fractal dimension that decreases upon increasing the magnetic\nfield intensity. By scaling arguments we also establish an analytical relation\nbetween the aggregate fractal dimension and the power law exponent controlling\nthe aggregation kinetics. This relation is indeed independent on the magnetic\nfield intensity. Despite the superparamagnetic character of our particles, we\nfurther prove the existence of a population of surviving aggregates able to\nmaintain their integrity after switching off the external magnetic field.\nFinally, we suggest a schematic interaction scenario to rationalize the\nobserved coexistence between reversible and irreversible aggregation.",
        "positive": "Effects of Thermal Modification on the Flexure Properties, Fracture\n  Energy, and Hardness of Western Hemlock: This study investigates the effect of thermal modification on the flexural\nproperties, transverse fracture energy, and hardness of western hemlock, a\nmaterial which is finding increasing applications in construction. Flexure\ntests on specimens featuring longitudinal and transverse grains showed that\nthermal modification at 167C slightly improves the flexural modulus and\nstrength and leads to less statistical variability compared to unmodified\nsamples. On the other hand, the fracture and Janka hardness tests revealed a\nmore pronounced brittleness of the thermally modified samples. In fact, the\ntotal mode I fracture energy of modified Single Edge Notch Bending (SENB)\nsamples was about 47% lower for radial-longitudinal systems and 60% lower for\ntangential-longitudinal systems. Similarly, the average Janka hardness in the\ntangential, radial, and transverse planes was 8.5%, 3.9%, and 9.4% lower in the\nmodified specimens, respectively. The results presented in this work show that\nthermal modification can have a significant effect on the fracturing behavior\nof western hemlock and its energy dissipation capabilities. For design, this\nmust be taken into serious consideration as these properties significantly\ninfluence the damage tolerance of this wood in the presence of stress\nconcentrations such as e.g., those induced in bolted joints and cut outs.\nFracture energy and hardness are also strongly correlated to ballistic\nperformance."
    },
    {
        "anchor": "Photoelastic Stress Response of Complex 3D-Printed Particle Shapes: While stress visualization within 3-dimensional particles would greatly\nadvance our understanding of the behaviors of complex particles, traditional\nphotoelastic methods suffer from a lack of available technology for producing\nsuitable complex particles. Recently, 3D-printing has created new possibilities\nfor enhancing the scope of stress analysis within physically representative\ngranules. Here, we investigate and evaluate opportunities offered by\n3D-printing a single particle with a complex external shape with photoelastic\nproperties. We report the results of X-ray computed tomography and 3D-printing,\ncombined with traditional photoelastic analysis, to visualize strain for\nparticles ranging from simple 2D discs to complex 3D printed coffee beans,\nincluding with internal voids. We find that the relative orientation of the\nprint layers and the loading force affects the optical response of the discs,\nbut without a significant difference in their mechanical properties.\nFurthermore, we present semi-quantitative measurements of stresses within\n3D-printed complex particles. The paper outlines the potential limitations and\nareas of future interest for stress visualization of 3-dimensional particles.",
        "positive": "Computer simulation of bottle brush polymers with flexible backbone:\n  Good solvent versus Theta solvent conditions: By Molecular Dynamics simulation of a coarse-grained bead-spring type model\nfor a cylindrical molecular brush with a backbone chain of $N_b$ effective\nmonomers to which with grafting density $\\sigma$ side chains with $N$ effective\nmonomers are tethered, several characteristic length scales are studied for\nvariable solvent quality. Side chain lengths are in the range $5 \\le N \\le 40$,\nbackbone chain lengths are in the range $50 \\le N_b \\le 200$, and we perform a\ncomparison to results for the bond fluctuation model on the simple cubic\nlattice (for which much longer chains are accessible, $N_b \\le 1027$, and which\ncorresponds to an athermal, very good, solvent). We obtain linear dimensions of\nside chains and the backbone chain and discuss their $N$-dependence in terms of\npower laws and the associated effective exponents. We show that even at the\nTheta point the side chains are considerably stretched, their linear dimension\ndepending on the solvent quality only weakly. Effective persistence lengths are\nextracted both from the orientational correlations and from the backbone\nend-to-end distance; it is shown that different measures of the persistence\nlength (which would all agree for Gaussian chains) are not mutually consistent\nwith each other, and depend distinctly both on $N_b$ and the solvent quality. A\nbrief discussion of pertinent experiments is given."
    },
    {
        "anchor": "What do the fast dynamics tell us about aggregation?: Two typical morphology of two-dimensional aggregates are considered: compact\ncrystalline clusters and string-like non-compact conformations. Simulated\ntrajectories of both types of aggregates are analysed with fine spatial\nresolution. While the long-time geometry of such trajectories appears to be\nstatistically identical for two conformations, the self-overlap statistics\nreveal two distinct short-time {\\em pre-caging} mechanisms. While the\ntime-scale is directly proportional with length-scale for particles in a\ncompact aggregates, an inverse relationship holds for non-compact clusters.\nThese short length-fast time relationship of particle localization might hold\nthe key to the structure-function relationship of aggregate forming systems and\nother non-equilibrium soft materials.",
        "positive": "Deterministic and stochastic control of kirigami topology: Kirigami, the creative art of paper cutting, is a promising paradigm for\nmechanical metamaterials. However, to make kirigami-inspired structures a\nreality requires controlling the topology of kirigami to achieve connectivity\nand rigidity. We address this question by deriving the maximum number of cuts\n(minimum number of links) that still allow us to preserve global rigidity and\nconnectivity of the kirigami. A deterministic hierarchical construction method\nyields an efficient topological way to control both the number of connected\npieces and the total degrees of freedom. A statistical approach to the control\nof rigidity and connectivity in kirigami with random cuts complements the\ndeterministic pathway, and shows that both the number of connected pieces and\nthe degrees of freedom show percolation transitions as a function of the\ndensity of cuts (links). Together this provides a general framework for the\ncontrol of rigidity and connectivity in planar kirigami."
    },
    {
        "anchor": "Generation of arbitrary Dicke states in spinor Bose-Einstein condensates: We demonstrate that the combination of two-body collisions and applied Rabi\npulses makes it possible to prepare arbitrary Dicke (spin) states as well as\nmaximally entangled states by appropriate sequencing of external fields.",
        "positive": "A self-consistent renormalized Jellium approach for calculating\n  structural and thermodynamic properties of charge stabilized colloidal\n  suspensions: An approach is proposed which allows to self-consistently calculate the\nstructural and thermodynamic properties of highly charged aqueous colloidal\nsuspensions. The method is based on the renormalized Jellium model with the\nbackground charge distribution related to the colloid-colloid correlation\nfunction. The theory is used to calculate the correlation functions and the\neffective colloidal charges for suspension containing additional monovalent\nelectrolyte. The predictions of the theory are in excellent agreement with the\nMonte Carlo simulations."
    },
    {
        "anchor": "Universal and non-universal features of glassy relaxation in propylene\n  carbonate: It is demonstrated that the susceptibility spectra of supercooled propylene\ncarbonate as measured by depolarized-light-scattering, dielectric-loss, and\nincoherent quasi-elastic neutron-scattering spectroscopy within the GHz window\nare simultaneously described by the solutions of a two-component schematic\nmodel of the mode-coupling theory (MCT) for the evolution of glassy dynamics.\nIt is shown that the universal beta-relaxation-scaling laws, dealing with the\nasymptotic behavior of the MCT solutions, describe the qualitative features of\nthe calculated spectra. But the non-universal corrections to the scaling laws\nrender it impossible to achieve a complete quantitative description using only\nthe leading-order-asymptotic results.",
        "positive": "Hybrid continuum-molecular modeling of fluid slip flow: Experiments on fluid systems in micro-/nano-scale solid conveyors have shown\na violation of the no-slip assumption that have been adopted by the classical\nfluid mechanics. To correct this mechanics for the fluid slip, various\napproaches have been proposed to determine the slip boundary conditions.\nHowever, these approaches have revealed contradictory results for a variety of\nsystems, and a debate on the mechanisms and the conditions of the fluid\nslip/no-slip past solid surfaces is sustained for a long time. In this paper,\nwe establish the hybrid continuum-molecular modeling (HCMM) as a general\napproach of modeling the fluid slip flow under the influence of excess\nfluid-solid molecular interactions. This modeling approach postulates that\nfluids flow over solid surfaces with/without slip depending on the difference\nbetween the applied impulse on the fluid and a drag due to the excess\nfluid-solid molecular interactions. In the HCMM, the Navier-Stokes equations\nare corrected for the excess fluid-solid interactions. Measures of the\nfluid-solid interactions are incorporated into the fluid viscosity. We\ndemonstrate that the correction of the fluid mechanics by the slip boundary\nconditions is not an accurate approach, as the fluid-solid interactions would\nimpact the fluid internally. To show the effectiveness of the proposed HCMM, it\nis implemented for water flow in nanotubes. The HCMM is validated by an\nextensive comparison with over 90 cases of experiments and molecular dynamics\nsimulations of different fluid systems. We foresee that the hybrid\ncontinuum-molecular modeling of the fluid slip flow will find many important\nimplementations in fluid mechanics."
    },
    {
        "anchor": "Star copolymers in porous environments: scaling and its manifestations: We consider star polymers, consisting of two different polymer species, in a\nsolvent subject to quenched correlated structural obstacles. We assume that the\ndisorder is correlated with a power-law decay of the pair correlation function\ng(x)\\sim x^{-a}. Applying the field-theoretical renormalization group approach\nin d dimensions, we analyze different scenarios of scaling behavior working to\nfirst order of a double \\epsilon=4-d, \\delta=4-a expansion. We discuss the\ninfluence of the correlated disorder on the resulting scaling laws and possible\nmanifestations such as diffusion controlled reactions in the vicinity of\nabsorbing traps placed on polymers as well as the effective short-distance\ninteraction between star copolymers.",
        "positive": "Universal reduction of pressure between charged surfaces by\n  long-wavelength surface charge modulation: We predict theoretically that long-wavelength surface charge modulations\nuniversally reduce the pressure between the charged surfaces with counterions\ncompared with the case of uniformly charged surfaces with the same average\nsurface charge density. The physical origin of this effect is the fact that\nsurface charge modulations always lead to enhanced counterion localization near\nthe surfaces, and hence, fewer charges at the midplane. We confirm the last\nprediction with Monte Carlo simulations."
    },
    {
        "anchor": "Yield in Amorphous Solids: The Ant in the Energy Landscape Labyrinth: It has recently been shown that yield in amorphous solids under oscillatory\nshear is a dynamical transition from asymptotically periodic to asymptotically\nchaotic, diffusive dynamics. However, the type and universality class of this\ntransition are still undecided. Here we show that the diffusive behavior of the\nvector of coordinates of the particles comprising an amorphous solid when\nsubject to oscillatory shear, is analogous to that of a particle diffusing in a\npercolating lattice, the so-called \"ant in the labyrinth\" problem, and that\nyield corresponds to a percolation transition in the lattice. We explain this\nas a transition in the connectivity of the energy landscape, which affects the\nphase-space regions accessible to the coordinate vector for a given maximal\nstrain amplitude. This transition provides a natural explanation to the\nobserved limit-cycles, periods larger than one and diverging time-scales at\nyield.",
        "positive": "Collective dynamics and rheology of confined phoretic suspensions: Similarly to their biological counterparts, suspensions of chemically-active\nautophoretic swimmers exhibit nontrivial dynamics involving self-organization\nprocesses as a result of inter-particle interactions. Using a kinetic model for\na dilute suspension of autochemotactic Janus particles, we analyse the effect\nof a confined pressure-driven flow on these collective behaviours and the\nimpact of chemotactic aggregation on the effective viscosity of the active\nfluid. Four dynamic regimes are identified when increasing the strength of the\nimposed pressure-driven flow, each associated with a different collective\nbehaviour resulting from the competition of flow- and chemically-induced\nreorientation of the swimmers together with the constraints of confinement.\nInterestingly, we observe that the effect of the pusher (resp. puller)\nhydrodynamic signature, which is known to reduce (resp. increase) the effective\nviscosity of a sheared suspension, is inverted upon the emergence of\nautochemotactic aggregation. Our results provide new insights on the role of\ncollective dynamics in complex environments, which are relevant to synthetic as\nwell as biological systems."
    },
    {
        "anchor": "Wetting and layering transitions of a spin-1/2 Ising model in a random\n  transverse field: The effect of a random transverse field (RTF) on the wetting and layering\ntransitions of a spin-1/2 Ising model, in the presence of bulk and surface\nfields, is studied within an effective field theory by using the differential\noperator technique. Indeed, the dependencies of the wetting temperature and\nwetting transverse field on the probability of the presence of a transverse\nfield are established. For specific values of the surface field we show the\nexistence of a critical probability $p_{c}$ above which wetting and layering\ntransitions disappear.",
        "positive": "Dependence of self-assembled amphiphile structure on interaction between\n  hydrophilic groups: In a previous study (Comp. Phys. Com.(2005) Vol.169, 139-143), we clarified\nthe dependence of the phase structure on the hydrophilicity of an amphiphilic\nmolecule by varying the interaction potential between the hydrophilic molecule\nand water(aAA) in a dissipative particle dynamics (DPD) simulation using the\nJury model. In the present paper, we perform another DPD simulation using the\nprevious model to investigate the dependence of the interaction potential\nbetween adjacent hydrophilic groups on the phase structure. By varying the\ncoefficient of the interaction potential between adjacent hydrophilic groups\naAA (aAA=15,25,40, and 250) at a dimensionless temperature of T=0.5 and a\nconcentration of amphiphilic molecules in water of phi=50%, hexagonal\n(aAA=14,25,40) and micellar (aAA=250) phases were observed. In comparison with\nthe previous results, the dependence of the A-B dimer's shape on aAA was\ndetermined to be weaker than that on aAA. Therefore, it is concluded that the\nsolvent water W plays an important role in aggregation of the A-B dimers."
    },
    {
        "anchor": "Anomalous transport in fractal media with randomly inhomogeneous\n  diffusion barrier: We investigate a contaminant transport in fractal media with randomly\ninhomogeneous diffusion barrier. The diffusion barrier is a low permeable\nmatrix with extremely rare high permeability pathways (punctures). At times,\nless than a characteristic matrix diffusion time, the problem is effectively\nbarrier-free with an effective source acting during the time t<<teff. The\npunctures result in a precursor contaminant concentration at short times and\nadditional stage of the asymptotic concentration distribution at long times. If\nthe size of the source surface area is large enough, the barrier can be\nconsidered as statistical homogeneous medium; otherwise, strong fluctuations\noccur.",
        "positive": "Crossovers in supercooled solvation water: Effects of hydrophilic &\n  hydrophobic interactions: We use systematic 8 ns ab initio molecular dynamics (AIMD) to study the\nstructure and dynamics of water in bulk, and close to both hydrophobic and\nhydrophilic (carbonyl) groups of tetramethylurea (TMU). We observe crossovers\nin the dynamical behavior around the hydrophobic group at $T_X = 256 \\pm 4$K\nand another one at $265 \\pm 5$K related to the relative strength of water-water\nand water-carbonyl hydrogen bonds (HBs). For bulk water, the temperature of the\napparent divergence in relaxation times is located at $T_c = 210 \\pm 10$K. To\nbetter identify the effects arising from the hydrophilic carbonyl group,\nsystems of water with a methane molecule were used as references. These\nfindings are related to the structural and thermodynamic transitions reported\nfor proteins in solution and may also play a role in the mechanism of cold\ndenaturation of proteins."
    },
    {
        "anchor": "Force Propagation in Active Cytoskeletal Networks: In biological systems, molecular-scale forces and motions are pivotal for\nenabling processes like motility, shape change, and replication. These forces\nand motions are organized, amplified, and transmitted across macroscopic scales\nby active materials such as the cytoskeleton, which drives micron-scale\ncellular movement and re-organization. Despite the integral role of active\nmaterials, understanding how molecular-scale interactions alter macroscopic\nstructure and force propagation remains elusive. This knowledge gap presents\nchallenges to the harnessing and regulation of such dynamics across diverse\nlength scales. Here, we demonstrate how mediating the bundling of microtubules\ncan shift active matter between a global force-transmitting phase and a local\nforce-dissipating phase. A fivefold increase in microtubule effective length\nresults in the transition from local to global phase with a hundredfold\nincrease in velocity autocorrelation. Through theory and simulation, we\nidentify signatures of a percolation-driven transition between the two phases.\nThis provides evidence for how force propagation can be generated when local\nmolecular interactions reach a sufficient length scale. We show that force\npropagation in the active matter system enables material transport.\nConsequently, we demonstrate that the global phase is capable of facilitating\nmillimeter-scale human cell transport and manipulation, as well as powering the\nmovement of aqueous droplets. These findings underscore the potential for\ndesigning active materials capable of force organization and transmission. Our\nresults lay the foundation for further exploration into the organization and\npropagation of forces/stresses in biological systems, thereby paving the way\nfor the engineering of active materials in synthetic biology and soft robotics.",
        "positive": "Helical Disruptions in Small Loops of DNA: The thermodynamical stability of DNA minicircles is investigated by means of\npath integral techniques. Hydrogen bonds between base pairs on complementary\nstrands can be broken by thermal fluctuations and temporary fluctuational\nopenings along the double helix are essential to biological functions such as\ntranscription and replication of the genetic information. Helix unwinding and\nbubble formation patterns are computed in circular sequences with variable\nradius in order to analyze the interplay between molecule size and appearance\nof helical disruptions. The latter are found in minicircles with $< 100$ base\npairs and appear as a strategy to soften the stress due to the bending and\ntorsion of the helix."
    },
    {
        "anchor": "Compaction of cereal grain: We report on simple shaking experiments to measure the compaction of a column\nof Firth oat grain. Such grains are elongated anisotropic particles with a\nbimodal polydispersity. In these experiments, the particle configurations start\nfrom an initially disordered, low-packing-fraction state and under vertical\nshaking evolve to a dense state with evidence of nematic-like structure at the\nsurface of the confining tube. This is accompanied by an increase in the\npacking fraction of the grain.",
        "positive": "Colloidal interactions and unusual crystallization versus de-mixing of\n  elastic multipoles formed by gold mesoflowers: Colloidal interactions in nematic liquid crystals can be described as\ninteractions between elastic multipoles that depend on particle shape,\ntopology, chirality, boundary conditions and induced topological defects. Here,\nwe describe a nematic colloidal system consisting of mesostructures of gold\ncapable of inducing elastic multipoles of different order. Elastic monopoles\nare formed by relatively large asymmetric mesoflower particles, for which\ngravity and elastic torque balancing yields monopole-type interactions.\nHigh-order multipoles are instead formed by smaller mesoflowers with a myriad\nof shapes corresponding to multipoles of different orders, consistent with our\ncomputer simulations based on free energy minimization. We reveal unexpected\nmany-body interactions in this colloidal system, ranging from de-mixing of\nelastic monopoles to a zoo of unusual colloidal crystals formed by high-order\nmultipoles like hexadecapoles. Our findings show that gold mesoflowers may\nserve as a designer toolkit for engineering colloidal interaction and\nself-assembly, potentially exceeding that in atomic and molecular systems."
    },
    {
        "anchor": "Improved Numerical Scheme for the Generalized Kuramoto Model: We present an improved and more accurate numerical scheme for a\ngeneralization of the Kuramoto model of coupled phase oscillators to the\nthree-dimensional space. The present numerical scheme relies crucially on our\nobservation that the generalized Kuramoto model corresponds to particles on the\nunit sphere undergoing rigid body rotations with position-dependent angular\nvelocities. We demonstrate that our improved scheme is able to reproduce known\nanalytic results and capture the expected behavior of the three-dimensional\noscillators in various cases. On the other hand, we find that the conventional\nnumerical method, which amounts to a direct numerical integration with the\nconstraint that forces the particles to be on the unit sphere at each time\nstep, may result in inaccurate and misleading behavior especially in the long\ntime limit. We analyze in detail the origin of the discrepancy between the two\nmethods and present the effectiveness of our method in studying the limit cycle\nof the Kuramoto oscillators.",
        "positive": "Interaction and self-assembly of membrane-binding and membrane-excluding\n  colloids embedded in lamellar phases: Within the framework of a discrete Gaussian model, we present analytical\nresults for the interaction induced by a lamellar phase between small embedded\ncolloids. We consider the two limits of particles strongly adherent to the\nadjacent membranes and of particles impenetrable to the membranes. Our approach\ntakes into account the finite size of the colloids, the discrete nature of the\nlayers, and includes the Casimir-like effect of fluctuations, which is very\nimportant for dilute phases. Monte Carlo simulations of the statistical\nbehavior of the membrane-interacting colloids account semi-quantitatively,\nwithout any adjustable parameters, for the experimental data measured on silica\nnanospheres inserted within lyotropic smectics. We predict the existence of\nfinite-size and densely packed particle aggregates originating from the\ncompetition between attractive interactions between colloids in the same layer\nand repulsion between colloids one layer apart."
    },
    {
        "anchor": "Nonequilibrium dynamics of polymer translocation and straightening: When a flexible polymer is sucked into a localized small hole, the chain can\ninitially respond only locally and the sequential nonequilibrium processes\nfollow in line with the propagation of the tensile force along the chain\nbackbone. We analyze this dynamical process by taking the nonuniform stretching\nof the polymer into account both with and without hydrodynamics interactions.\nEarlier conjectures on the absorption time are criticized and new formulae are\nproposed together with time evolutions of relevant dynamical variables.",
        "positive": "Active spheres induce Marangoni flows that drive collective dynamics: For monolayers of chemically active particles at a fluid interface,\ncollective dynamics are predicted to arise owing to activity-induced Marangoni\nflow even if the particles are not self-propelled. Here we test this prediction\nby employing a monolayer of spherically symmetric active TiO_2 particles\nlocated at an oil-water interface with or without addition of a non-ionic\nsurfactant. Due to the spherical symmetry, an individual particle does not\nself-propel. However, the gradients produced by the photochemical fuel\ndegradation give rise to long-ranged Marangoni flows. For the case in which\nsurfactant is added to the system, we indeed observe the emergence of\ncollective motion, with dynamics dependent on the particle coverage of the\nmonolayer. The experimental observations are discussed within the framework of\na simple theoretical mean field model."
    },
    {
        "anchor": "Shape and Fluctuations of Positively Curved Ribbons: We study the shape and shape fluctuations of positively curved ribbons, with\na flat reference metric and a sphere-like reference curvature. Such\nincompatible geometry is likely to occur in many self assembled materials and\nother experimental systems. Such ribbons exhibit a sharp transition between\nrigid ring and an anomalously soft spring as a function of their width. As a\nresult, the temperature dependence of these ribbons' shape is unique,\nexhibiting a non-monotonic dependence of the persistence and Kuhn lengths on\nthe temperature and width. We map the possible configuration phase space and\nshow the existence of three phases- at high temperatures it is the Ideal Chain\nphase, where the ribbon is well described by classical models (e.g- worm like\nchain model); The second phase, for cold and narrow ribbons, is the Plain\nErgodic phase - a ribbon in this phase might be thought of as made out of\nsegments that gyrate within an oblate spheroid with extreme aspect ratio; The\nthird phase, for cold, wide ribbons, is a direct result of the residual stress\ncaused by the incompatibility, called Random Structured phase. A ribbon in this\nphase behaves on large scales as an Ideal Chain, however the segments of this\nchain are not straight, rather they may have different shapes, mainly helices\n(both left and right handed) of various pitches.",
        "positive": "Experimental Study of Thermodiffusion and Thermoelectricity in Charged\n  Colloids: The Seebeck and Soret coefficients of ionically stabilized suspension of\nmaghemite nanoparticles in dimethyl sulfoxide are experimentally studied as a\nfunction of nanoparticle volume fraction. In the presence of a temperature\ngradient, the charged colloidal nanoparticles experience both thermal drift due\nto their interactions with the solvent molecules and electric forces\nproportional to the internal thermoelectric field. The resulting\nthermodiffusion of nanoparticles is observed through Forced Rayleigh\nscattering, while the thermoelectric field is accessed through voltage\nmeasurements in a thermocell. Both techniques provide independent estimates of\nnanoparticle's entropy of transfer as high as 75 meV/K. Such a property may be\nused to improve the thermoelectric coefficients in liquid thermocells."
    },
    {
        "anchor": "Particle-Size Effects in the Formation of Bicontinuous Pickering\n  Emulsions: We demonstrate that the formation of bicontinuous emulsions stabilized by\ninterfacial particles (bijels) is more robust when nanoparticles rather than\nmicroparticles are used. Emulsification via spinodal demixing in the presence\nof nearly neutrally wetting particles is induced by rapid heating. Using\nconfocal microscopy, we show that nanospheres allow successful bijel formation\nat heating rates two orders of magnitude slower than is possible with\nmicrospheres. In order to explain our results, we introduce the concept of\nmechanical leeway i.e. nanoparticles benefit from a smaller driving force\ntowards disruptive curvature. Finally, we suggest that leeway mechanisms may\nbenefit any formulation in which challenges arise due to tight restrictions on\na pivotal parameter, but where the restrictions can be relaxed by rationally\nchanging the value of a more accessible parameter.",
        "positive": "Geometry and topology of turbulence in active nematics: The problem of low Reynolds number turbulence in active nematic fluids is\ntheoretically addressed. Using numerical simulations I demonstrate that an\nincompressible turbulent flow, in two-dimensional active nematics, consists of\nan ensemble of vortices whose areas are exponentially distributed within a\nrange of scales. Building on this evidence, I construct a mean-field theory of\nactive turbulence by which several measurable quantities, including the\nspectral densities and the correlation functions, can be analytically\ncalculated. Because of the profound connection between the flow geometry and\nthe topological properties of the nematic director, the theory sheds light on\nthe mechanisms leading to the proliferation of topological defects in active\nnematics and provides a number of testable predictions. A hypothesis, inspired\nby Onsager's statistical hydrodynamics, is finally introduced to account for\nthe equilibrium probability distribution of the vortex sizes."
    },
    {
        "anchor": "Phase ordering, topological defects, and turbulence in the 3D\n  incompressible Toner-Tu equation: We investigate phase ordering dynamics of the incompressible Toner-Tu\nequation in three dimensions. We show that the phase ordering proceeds via\ndefect merger events and the dynamics is controlled by the Reynolds number Re.\nAt low Re, the dynamics is similar to that of the Ginzburg-Landau equation. At\nhigh Re, turbulence controls phase ordering. In particular, we observe a\nforward energy cascade from the coarsening length scale to the dissipation\nscale.",
        "positive": "Trapping of Quantized Electrical Charge in Superfluid 3He-B via the\n  Electrodynamics of Spin-orbit Coupled Systems: Exploiting analogies between spin-orbit coupled spin superfluids and\nnon-Abelian Yang-Mills theory, we argue that machines can be built capable of\ntrapping a quantized amount of electric linear charge density, while the line\ncharge quantum itself is surprisingly large. The required conditions might well\nhold in superfluid 3He-B, for which we propose an experimental realization of\nthis phenomenon."
    },
    {
        "anchor": "Mass separation in an asymmetric channel: We present a mechanism to sort out particles of different masses in an\nasymmetric channel, where the entropic barriers arise naturally and control the\ndiffusion of these particles. When particles are subjected to an oscillatory\nforce, with the scaled amplitude $a$ and frequency $\\omega$, the mean particle\nvelocity exhibits a bell-shaped behavior as a function of the particle mass,\nindicating that particles with an optimal mass $m_{op}$ drift faster than other\nparticles. By tuning $a$ and $\\omega$, we get an empirical relation to estimate\n$m_{op} \\sim (a\\,\\omega^2)^{-0.4}$. An additional static bias, applied in the\nopposite direction of the rectified velocity, would push the particles of\nlighter mass to move in its direction while the others drift opposite to it.\nThis study is useful to design lab-on-a-chip devices for separating particles\nof different masses.",
        "positive": "Degenerate ground states and stability of spatial solitons in\n  quasi-one-dimensional Bose-Einstein Condensates: By examining the bound-state spectra of transverse fluctuations about\none-dimensional, spatially localized dark and bright soliton wavetrains of the\nGross-Pitaevskii equation, it is established that the low-temperature ground\nstates of repulsive and attractive quasi-one-dimensional Bose-Einstein\ncondensates are degenerate. In the one-soliton limit, both ground states are\nshown to possess two distinct transverse fluctuation modes which can couple to\nthe spatial soliton: the first involves zero-energy exchange, costing only the\nsoliton shape dressing via uniform translation of its centre of mass. The\nsecond mode contributes in a negative energy for the repulsive case, but\npositive energy in the attractive case. This unstability of the repulsive\nspatial soliton against localized transverse fluctuation modes invalidates the\nGross-Pitaevskii equation for stationary solitonic processes in repulsive 1D\nBose-Einstein-Condensate systems."
    },
    {
        "anchor": "Sizing multimodal suspensions with differential dynamic microscopy: Differential dynamic microscopy (DDM) can be used to extract mean particle\nsize from videos of suspensions. However, many suspensions have multimodal\nparticle size distributions (PSDs), for which this is not a sufficient\ndescription. After clarifying how different particle sizes contribute to the\nsignal in DDM, we show that standard DDM analysis can extract the mean sizes of\ntwo populations in a bimodal suspension given prior knowledge of the sample's\nbimodality. Further, the use of the CONTIN algorithm obviates the need for such\nprior knowledge. Finally, we show that by selectively analysing portions of the\nDDM images, we can size a trimodal suspension where the large particles would\notherwise dominate the signal, again without prior knowledge of the\ntrimodality.",
        "positive": "Repulsive and attractive depletion forces mediated by nonadsorbing\n  polyelectrolytes in the Donnan limit: In mixtures of colloids and nonadsorbing polyelectrolytes, a Donnan potential\narises across the region between surfaces that are depleted of polyelectrolyte\nand the rest of the system. This Donnan potential tends to shift the\npolyelectrolyte density profile towards the colloidal surface and leads to\nlocal accumulation of polyelectrolytes. We derive a zero-field theory for the\ndisjoining pressure between two parallel flat plates. Polyelectrolyte is\nallowed to enter the confined interplate region at the cost of a conformational\nfree energy penalty. The resulting disjoining pressure shows a crossover to a\nrepulsive regime when the interplate separation gets smaller than the size of\nthe polyelectrolyte chain, followed by an attractive part. We find a\nquantitative match between the model and self-consistent field computations\nthat take into account the full Poisson-Boltzmann electrostatics."
    },
    {
        "anchor": "A simply solvable model capturing the approach to statistical\n  self-similarity for the diffusive coarsening of bubbles, droplets, and grains: Aqueous foams and a wide range of related systems are believed to coarsen by\ngas diffusion between neighboring domains into a statistically self-similar\nscaling state, after the decay of initial transients, such that dimensionless\nsize and shape distributions become time independent and the average grows as a\npower law. Partial integrodifferential equations for the time evolution of the\nsize distribution for such phase separating systems can be formulated for\narbitrary initial conditions, but these are cumbersome for analyzing data on\nnon-scaling state preparations. Here we show that essential features of the\napproach to the scaling state can be captured by an exactly-solvable ordinary\ndifferential equation for the evolution of the average bubble size. The key\ningredient is to characterize the the bubble size distribution approximately,\nusing the average size of all bubbles and the average size of the critical\nbubbles, which instantaneously neither grow nor shrink. The difference between\nthese two averages serves as a proxy for the width of the size distribution. To\ntest our model, we compare with data for quasi-two dimensional dry foams\ncreated with three different initial amounts of polydispersity. This allows us\nto readily identify the critical radius from the average area of six-sided\nbubbles, whose growth rate is zero by the von~Neumann law. The growth of the\naverage and critical radii agree quite well with exact solution, though the\nmost monodisperse sample crosses over to the scaling state faster than\nexpected. A simpler approximate solution of our model performs equally well.\nOur approach is applicable to 3d foams, which we demonstrate by re-analyzing\nprior data, as well as to froths of dilute droplets and to phase separation\nkinetics for more general systems such as emulsions, binary mixtures, and\nalloys.",
        "positive": "Dewetting of a solid monolayer: We report on the dewetting of a monolayer on a solid substrate, where mass\ntransport occurs via surface diffusion. For a wide range of parameters, a\nlabyrinthine pattern of bilayer islands is formed. An irreversible regime and a\nthermodynamic regime are identified. In both regimes, the velocity of a\ndewetting front, the wavelength of the bilayer island pattern, and the rate of\nnucleation of dewetted zones are obtained. We also point out the existence of a\nscaling behavior, which is analyzed by means of a geometrical model."
    },
    {
        "anchor": "A simple spin model for three steps relaxation and secondary proccesses\n  in glass formers: A number of general trends are known to occur in systems displaying secondary\nprocesses in glasses and glass formers. Universal features can be identified as\ncomponents of large and small cooperativeness whose competition leads to excess\nwings or apart peaks in the susceptibility spectrum. To the aim of\nunderstanding such rich and complex phenomenology we analyze the behavior of a\nmodel combining two apart glassy components with a tunable different\ncooperativeness. The model salient feature is, indeed, based on the competition\nof the energetic contribution of groups of dynamically relevant variables,\ne.g., density fluctuations, interacting in small and large sets. We investigate\nhow the model is able to reproduce the secondary processes physics without\nfurther ad hoc ingredients, displaying known trends and properties under\ncooling or pressing.",
        "positive": "Quantifying surface wetting properties using droplet probe AFM: Surface wettability has a huge influence on its functional properties. For\nexample, to minimize smudging, surfaces should be able to repel oil droplets.\nTo quantify surface wettability, the most common approach is to measure the\ncontact angles of a liquid droplet on the surface. While well-established and\nrelatively easy to perform, contact angle measurements are crude and imprecise;\nmoreover, they cannot spatially resolve surface heterogeneities that can\ncontribute to surface fouling. To address these shortcomings, we report on\nusing an Atomic Force Microscopy (AFM) technique to quantitatively measure the\ninteraction forces between a micro-droplet and a surface with piconewton force\nresolution. We show how our technique can be used to spatially map\ntopographical and chemical heterogeneities with micron resolution."
    },
    {
        "anchor": "Ultra-long range correlations of the dynamics of jammed soft matter: We use Photon Correlation Imaging, a recently introduced space-resolved\ndynamic light scattering method, to investigate the spatial correlation of the\ndynamics of a variety of jammed and glassy soft materials. Strikingly, we find\nthat in deeply jammed soft materials spatial correlations of the dynamics are\nquite generally ultra-long ranged, extending up to the system size, orders of\nmagnitude larger than any relevant structural length scale, such as the\nparticle size, or the mesh size for colloidal gel systems. This has to be\ncontrasted with the case of molecular, colloidal and granular ``supercooled''\nfluids, where spatial correlations of the dynamics extend over a few particles\nat most. Our findings suggest that ultra long range spatial correlations in the\ndynamics of a system are directly related to the origin of elasticity. While\nsolid-like systems with entropic elasticity exhibit very moderate correlations,\nsystems with enthalpic elasticity exhibit ultra-long range correlations due to\nthe effective transmission of strains throughout the contact network.",
        "positive": "Wavelength selection in a buckling garden hose: We consider sinusoidal undulations which appear on certain garden hoses under\nnormal use. We propose an explanation and provide a model for this phenomenon,\nand make a connection with biological structures as well as self-buckling. We\ncompare observations with model predictions, and suggest potential applications\nin the area of shape-changing materials."
    },
    {
        "anchor": "Hard sphere fluids in annular wedges: density distributions and\n  depletion potentials: We analyze the density distribution and the adsorption of solvent hard\nspheres in an annular slit formed by two large solute spheres or a large solute\nand a wall at close distances by means of fundamental measure density\nfunctional theory, anisotropic integral equations and simulations. We find that\nthe main features of the density distribution in the slit are described by an\neffective, two--dimensional system of disks in the vicinity of a central\nobstacle. For large solute--solvent size ratios, the resulting depletion force\nhas a straightforward geometrical interpretation which gives a precise\n\"colloidal\" limit for the depletion interaction. For intermediate size ratios\n5...10 and high solvent packing fractions larger than 0.4, the explicit density\nfunctional results show a deep attractive well for the depletion potential at\nsolute contact, possibly indicating demixing in a binary mixture at low solute\nand high solvent packing fraction.",
        "positive": "A rheological state diagram for rough colloids in shear flow: The flow of dense suspensions, glasses, and granular materials is heavily\ninfluenced by frictional interactions between constituent particles. However,\nneither hydrodynamics nor friction has successfully explained the full range of\nflow phenomena in concentrated suspensions. Particles with asperities represent\na case in point. Lubrication hydrodynamics fail to completely capture two key\nrheological properties - namely, that the viscosity increases drastically and\nthe first normal stress difference can switch signs as volume fraction\nincreases. Yet, simulations that account for interparticle friction are also\nunable to fully predict these properties. Furthermore, experiments show that\nrheological behavior can vary depending on particle roughness and\ndeformability. We seek to resolve these apparent contradictions by\nsystematically tuning the roughness of model colloids, investigating their\nviscosity and first normal stress differences under steady shear, and finally\ngenerating a rheological state diagram that demonstrates how surface roughness\ninfluences the transition between shear thickening and dilatancy. Our\nsimulations, which are in good agreement with the experiments, suggest that\nfriction between rough particles is significant. In addition, we find that\nroughness progressively lowers the critical conditions required for the onset\nof shear thickening and dilatancy. Our results thus provides a major\ncontribution in the field of suspension rheology with broad relevance to\ngranular and particulate materials. For instance, particle geometry can be\ntuned to increase the efficacy of materials that turn solid-like on the\napplication of stimuli. On the other hand, engineers who work with concentrated\nslurries can now use images of the constituent particles to estimate optimal\nflow processing conditions."
    },
    {
        "anchor": "Creep motion of a granular pile induced by thermal cycling: We report a time-resolved study of the dynamics associated with the slow\ncompaction of a granular column submitted to thermal cycles. The column height\ndisplays a complex behavior: for a large amplitude of the temperature cycles,\nthe granular column settles continuously, experiencing a small settling at each\ncycle; By contrast, for small-enough amplitude, the column exhibits a\ndiscontinuous and intermittent activity: successive collapses are separated by\nquiescent periods whose duration is exponentially distributed. We then discuss\npotential mechanisms which would account for both the compaction and the\ntransition at finite amplitude.",
        "positive": "Density Profiles of Liquid/Vapor Interfaces Away from Their Critical\n  Point: We examine the applicability of various model profiles for the liquid/vapor\ninterface by X-ray reflectivities on water and ethanol and their mixtures at\nroom temperature. Analysis of the X-ray reflecivities using various density\nprofiles shows an error-function like profile is the most adequate within\nexperimental error. Our finding, together with recent observations from\nsimulation studies on liquid surfaces, strongly suggest that the capillary-wave\ndynamics shapes the interfacial density profile in terms of the error function."
    },
    {
        "anchor": "Density anomaly of charged hard spheres of different diameters in a\n  mixture with core-softened model solvent. Monte Carlo simulation results: Very recently the effect of equisized charged hard sphere solutes in a\nmixture with core-softened fluid model on the structural and thermodynamic\nanomalies of the system has been explored in detail by using Monte Carlo\nsimulations and integral equations theory [J. Chem. Phys., 2012, 137, 244502].\nOur objective of the present short work is to complement this study by\nconsidering univalent ions of unequal diameters in a mixture with the same\nsoft-core fluid model. Specifically, we are interested in the analysis of\nchanges of the temperature of maximum density (TMD) lines with ion\nconcentration for three model salt solutes, namely sodium chloride, potassium\nchloride and rubidium chloride models. We resort to Monte Carlo simulations for\nthis purpose. Our discussion also involves the dependences of the pair\ncontribution to excess entropy and of constant volume heat capacity on the\ntemperature of maximum density line. Some examples of the microscopic structure\nof mixtures in question in terms of pair distribution functions are given in\naddition.",
        "positive": "The shape and erosion of pebbles: The shapes of flat pebbles may be characterized in terms of the statistical\ndistribution of curvatures measured along their contours. We illustrate this\nnew method for clay pebbles eroded in a controlled laboratory apparatus, and\nalso for naturally-occurring rip-up clasts formed and eroded in the Mont\nSt.-Michel bay. We find that the curvature distribution allows finer\ndiscrimination than traditional measures of aspect ratios. Furthermore, it\nconnects to the microscopic action of erosion processes that are typically\nfaster at protruding regions of high curvature. We discuss in detail how the\ncurvature may be reliable deduced from digital photographs."
    },
    {
        "anchor": "Mechanics and Modeling of Cold Rolling of Polymeric Films at Large\n  Strains -- A Rate-Independent Approach: We analyze plane strain cold rolling processes, at large strains but slow\nstrain rates, by finite element modeling. At low temperatures, slow strain\nrates, and moderate thickness reductions during rolling (at which Bauschinger\neffect can be neglected for the particular class of polymeric films studied\nhere), the task of material modeling is greatly simplified, and enables us to\ndeploy a computationally efficient, yet accurate, finite deformation\nrate-independent elastic-plastic material behavior (with inclusion of\nisotropic-hardening). The finite deformation elastic-plastic material behavior\nbased on (i) hypoelasticity, and ii) multiplicative plasticity, are programmed\nand carried out for cold rolling within Abaqus Explicit. Predictions from both\nthe formulations, i.e., hypoelastic and multiplicative decomposition, exhibit a\nclose match with the experimentally observed rolling loads. We find that no\nspecialized hyperlastic/visco-plastic material model is required to describe\nthe behavior of the particular blend of polymeric films, under the conditions\ndescribed here, thereby significantly speeding up the computation for\nsteady-state rolling simulations. Moreover, the use of classical rigid-plastic\nmodeling (which is often applicable to metals) is found to greatly\nunderestimate the rolling loads for polymers, due to large elastic stretches in\nthe polymer films at large strains.",
        "positive": "New analytical progress in the theory of vesicles under linear flow: Vesicles are becoming a quite popular model for the study of red blood cells\n(RBCs). This is a free boundary problem which is rather difficult to handle\ntheoretically. Quantitative computational approaches constitute also a\nchallenge. In addition, with numerical studies, it is not easy to scan within a\nreasonable time the whole parameter space. Therefore, having quantitative\nanalytical results is an essential advance that provides deeper understanding\nof observed features and can be used to accompany and possibly guide further\nnumerical development. In this paper shape evolution equations for a vesicle in\na shear flow are derived analytically with precision being cubic (which is\nquadratic in previous theories) with regard to the deformation of the vesicle\nrelative to a spherical shape. The phase diagram distinguishing regions of\nparameters where different types of motion (tank-treading, tumbling and\nvacillating-breathing) are manifested is presented. This theory reveals\nunsuspected features: including higher order terms and harmonics (even if they\nare not directly excited by the shear flow) is necessary, whatever the shape is\nclose to a sphere. Not only does this theory cure a quite large quantitative\ndiscrepancy between previous theories and recent experiments and numerical\nstudies, but also it reveals a new phenomenon: the VB mode band in parameter\nspace, which is believed to saturate after a moderate shear rate, exhibits a\nstriking widening beyond a critical shear rate. The widening results from\nexcitation of fourth order harmonic. The obtained phase diagram is in a\nremarkably good agreement with recent three dimensional numerical simulations\nbased on the boundary integral formulation. Comparison of our results with\nexperiments is systematically made."
    },
    {
        "anchor": "Vesicle shape transformations driven by confined active filaments: In active matter systems, deformable boundaries provide a mechanism to\norganize internal active stresses and perform work on the external environment.\nTo study a minimal model of such a system, we perform particle-based\nsimulations of an elastic vesicle containing a collection of polar active\nfilaments. The interplay between the active stress organization due to\ninterparticle interactions and that due to the deformability of the confinement\nleads to a variety of filament spatiotemporal organizations that have not been\nobserved in bulk systems or under rigid confinement, including highly-aligned\nrings and caps. In turn, these filament assemblies drive dramatic and tunable\ntransformations of the vesicle shape and its dynamics. We present simple\nscaling models that reveal the mechanisms underlying these emergent behaviors\nand yield design principles for engineering active materials with targeted\nshape dynamics.",
        "positive": "Effect of Annealed Disorder on Phase Separation Kinetics and Aging\n  Phenomena in Fluid Mixtures: We use state-of-the-art molecular dynamics simulations to study the effects\nof annealed disorder on the phase separating kinetics and aging phenomena of a\nsegregating binary fluid mixture. In the presence of disorder, we observe a\ndramatic slowing down in the phase separation dynamics. The domain growth\nfollows the power-law with a disorder-dependent exponent. Due to the\nenergetically favorable positions, the domain boundary roughens which modifies\nthe correlation function and structure factor to a non-Porod behavior. The\ncorrelation function and structure factor provide clear evidence that the\nsuperuniversality does not hold in our system. The role of annealed disorder on\nthe non-equilibrium aging dynamics is studied qualitatively by computing the\ntwo-time order parameter autocorrelation function. The decay of the correlation\nfunction slows down significantly with the disorder. This quantity exhibits\nscaling laws with respect to the ratio of the domain length at the observation\ntime and the age of the system. We find the scaling laws hold good for the\ndisordered system and therefore, robust and generic to such segregating fluid\nmixtures."
    },
    {
        "anchor": "Sufficient conditions for the additivity of stall forces generated by\n  multiple filaments or motors: Molecular motors and cytoskeletal filaments work collectively most of the\ntime under opposing forces. This opposing force may be due to cargo carried by\nmotors or resistance coming from the cell membrane pressing against the\ncytoskeletal filaments. Some recent studies have shown that the collective\nmaximum force (stall force) generated by multiple cytoskeletal filaments or\nmolecular motors may not always be just a simple sum of the stall forces of the\nindividual filaments or motors. To understand this excess or deficit in the\ncollective force, we study a broad class of models of both cytoskeletal\nfilaments and molecular motors. We argue that the stall force generated by a\ngroup of filaments or motors is additive, that is, the stall force of $N$\nnumber of filaments (motors) is $N$ times the stall force of one filament\n(motor), when the system is in equilibrium at stall. Conversely, we show that\nthis additive property typically does not hold true when the system is not at\nequilibrium at stall. We thus present a novel and unified understanding of the\nexisting models exhibiting such non-addivity, and generalise our arguments by\ndeveloping new models that demonstrate this phenomena. We also propose a\nquantity similar to thermodynamic efficiency to easily predict this deviation\nfrom stall-force additivity for filament and motor collectives.",
        "positive": "Connection between partial pressure, volatility, and the Soret effect\n  elucidated using simulations of non-ideal liquid mixtures: Building on recent simulation work, it is demonstrated using\nmolecular-dynamics (MD) simulations of two-component liquid mixtures that the\nchemical contribution to the Soret effect in two-component non-ideal fluid\nmixtures arises due to differences in how the partial pressures of the\ncomponents respond to temperature and density gradients. Further insight is\nobtained by reviewing the connection between activity and deviations from\nRaoult's law in the measurement of the vapor pressure of a liquid mixture. A\nnew parameter gamma, defined in a manner similar to the activity coefficient,\nis used to characterize differences deviations from ``ideal'' behavior. It is\nthen shown that the difference gamma2-gamma1 is predictive of the sign of the\nSoret coefficient and is correlated to its magnitude. We hence connect the\nSoret effect to the relative volatility of the components of a liquid mixture,\nwith the more volatile component enriched in the low-density, high-temperature\nregion, and the less volatile component enriched in the high-density,\nlow-temperature region. Because gamma is closely connected to the activity\ncoefficient, this suggests the possibility that measurement of partial vapor\npressures might be used to indirectly determine the Soret coefficient. It is\nproposed that the insight obtained here is quite general and should be\napplicable to a wide range of materials systems. An attempt is made to\nunderstand how these results might apply to other materials systems including\ninterstitials in solids and multicomponent solids with interdiffusion occurring\nvia a vacancy mechanism."
    },
    {
        "anchor": "How do ionic superdiscs self-assemble in nanopores?: Discotic ionic liquid crystals (DILCs) consist of self-assembled superdiscs\nof cations and anions that spontaneously stack in linear columns with high\none-dimensional ionic and electronic charge mobility, making them prominent\nmodel systems for functional soft matter. Unfortunately, a homogeneous\nalignment of DILCs on the macroscale is often not achievable, which\nsignificantly limits their applicability. Infiltration into nanoporous solid\nscaffolds can in principle overcome this drawback. However, due to the extreme\nexperimental challenges to scrutinise liquid crystalline order in extreme\nspatial confinement, little is known about the structures of DILCs in\nnanopores. Here, we present temperature-dependent high-resolution optical\nbirefringence measurement and 3D reciprocal space mapping based on\nsynchrotron-based X-ray scattering to investigate the thermotropic phase\nbehaviour of dopamine-based ionic liquid crystals confined in cylindrical\nchannels of 180~nm diameter in macroscopic anodic aluminum oxide (AAO)\nmembranes. As a function of the membranes' hydrophilicity and thus the\nmolecular anchoring to the pore walls (edge-on or face-on) and the variation of\nthe hydrophilic-hydrophobic balance between the aromatic cores and the alkyl\nside chain motifs of the superdiscs by tailored chemical synthesis, we find a\nparticularly rich phase behaviour, which is not present in the bulk state. It\nis governed by a complex interplay of liquid crystalline elastic energies\n(bending and splay deformations), polar interactions and pure geometric\nconfinement, and includes textural transitions between radial and axial\nalignment of the columns with respect to the long nanochannel axis.",
        "positive": "Elongation and percolation of defect motifs in anisotropic packing\n  problems: We examine the regime between crystalline and amorphous packings of\nanisotropic objects on surfaces of different genus by continuously varying\ntheir size distribution or shape from monodispersed spheres to bidispersed\nmixtures or monodispersed ellipsoidal particles; we also consider an\nanisotropic variant of the Thomson problem with a mixture of charges. With\nincreasing anisotropy, we first observe the disruption of translational order\nwith an intermediate orientationally ordered hexatic phase as proposed by\nNelson, Rubinstein and Spaepen, and then a transition to amorphous state. By\nanalyzing the structure of the disclination motifs induced, we show that the\nhexatic-amorphous transition is caused by the growth and connection of\ndisclination grain boundaries, suggesting this transition lies in the\npercolation universality class in the scenarios considered."
    },
    {
        "anchor": "Non-equilibrium Theory of Arrested Spinodal Decomposition: The Non-equilibrium Self-consistent Generalized Langevin Equation theory of\nirreversible relax- ation [Phys. Rev. E (2010) 82, 061503; ibid. 061504] is\napplied to the description of the non- equilibrium processes involved in the\nspinodal decomposition of suddenly and deeply quenched simple liquids. For\nmodel liquids with hard-sphere plus attractive (Yukawa or square well) pair\npotential, the theory predicts that the spinodal curve, besides being the\nthreshold of the thermo- dynamic stability of homogeneous states, is also the\nborderline between the regions of ergodic and non-ergodic homogeneous states.\nIt also predicts that the high-density liquid-glass transition line, whose\nhigh-temperature limit corresponds to the well-known hard-sphere glass\ntransition, at lower temperature intersects the spinodal curve and continues\ninside the spinodal region as a glass-glass transition line. Within the region\nbounded from below by this low-temperature glass-glass tran- sition and from\nabove by the spinodal dynamic arrest line we can recognize two distinct domains\nwith qualitatively different temperature dependence of various physical\nproperties. We interpret these two domains as corresponding to full gas-liquid\nphase separation conditions and to the for- mation of physical gels by arrested\nspinodal decomposition. The resulting theoretical scenario is consistent with\nthe corresponding experimental observations in a specific colloidal model\nsystem.",
        "positive": "Multi-time density correlation functions in glass-forming liquids:\n  Probing dynamical heterogeneity and its lifetime: A multi-time extension of a density correlation function is introduced to\nreveal temporal information about dynamical heterogeneity in glass-forming\nliquids. We utilize a multi-time correlation function that is analogous to the\nhigher-order response function analyzed in multidimensional nonlinear\nspectroscopy. Here, we provide comprehensive numerical results of the\nfour-point, three-time density correlation function from longtime trajectories\ngenerated by molecular dynamics simulations of glass-forming binary soft-sphere\nmixtures. We confirm that the two-dimensional representations in both time and\nfrequency domains are sensitive to the dynamical heterogeneity and that it\nreveals the couplings of correlated motions, which exist over a wide range of\ntime scales. The correlated motions detected by the three-time correlation\nfunction is divided into mobile and immobile contributions that are determined\nfrom the particle displacement during the first time interval. We show that the\npeak positions of the correlations are in accord with the information on the\nnon-Gaussian parameters of the van-Hove self correlation function. Furthermore,\nit is demonstrated that the progressive changes in the second time interval in\nthe three-time correlation function enable us to analyze how correlations in\ndynamics evolve in time. From this analysis, we evaluated the lifetime of the\ndynamical heterogeneity and its temperature dependence systematically. Our\nresults show that the lifetime of the dynamical heterogeneity becomes much\nslower than the $\\alpha$-relaxation time that is determined from the two-point\ndensity correlation function when the system is highly supercooled."
    },
    {
        "anchor": "Phase separation of self-propelled ballistic particles: Self-propelled particles phase separate into coexisting dense and dilute\nregions above a critical density. The statistical nature of their stochastic\nmotion lends itself to various theories that predict the onset of phase\nseparation. However, these theories are ill equipped to describe such behavior\nwhen noise become negligible. To overcome this limitation, we present a\npredictive model that relies on two density-dependent timescales: $\\tau_F$, the\nmean time particles spend between collisions; and $\\tau_C$, the mean lifetime\nof a collision. We show that only when $\\tau_F < \\tau_C$ do collisions last\nlong enough to develop a growing cluster and initiate phase separation. Using\nboth analytical calculations and active particle simulations, we measure these\ntimescales and determine the critical density for phase separation in both 2D\nand 3D.",
        "positive": "All-Optical Production of a Degenerate Fermi Gas: We achieve degeneracy in a mixture of the two lowest hyperfine states of\n$^6$Li by direct evaporation in a CO$_2$ laser trap, yielding the first\nall-optically produced degenerate Fermi gas. More than $10^5$ atoms are\nconfined at temperatures below $4 \\mu$K at full trap depth, where the Fermi\ntemperature for each state is $8 \\mu$K. This degenerate two-component mixture\nis ideal for exploring mechanisms of superconductivity ranging from Cooper\npairing to Bose condensation of strongly bound pairs."
    },
    {
        "anchor": "Steady state cyclic behaviour of a half-plane contact in partial slip\n  subject to varying normal load, moment, shear load, and moderate differential\n  bulk tension: A new solution for a general half-plane contact in the steady state is\npresented. The contacting bodies are subject to a set of constant loads -\nnormal force, shear force and bulk tension parallel with the interface -\ntogether with an oscillatory set of the same quantities. Partial slip\nconditions are expected to ensue for a range of these quantities. In addition,\nthe line of action of the normal load component does not necessarily need to\npass the centre-line of the contact, thereby introducing a moment and asymmetry\nin the contact extent. This advancement enables a mapping to be formalised\nbetween the normal and tangential problem. An exact and easy to apply recipe is\ndefined.",
        "positive": "Scaling Description of Dynamical Heterogeneity and Avalanches of\n  Relaxation in Glass-Forming Liquids: We provide a theoretical description of dynamical heterogeneities in\nglass-forming liquids, based on the premise that relaxation occurs via local\nrearrangements coupled by elasticity. In our framework, the growth of the\ndynamical correlation length $\\xi$ and of the correlation volume $\\chi_4$ are\ncontrolled by a zero-temperature fixed point. We connect this critical behavior\nto the properties of the distribution of local energy barriers at zero\ntemperature. Our description makes a direct connection between dynamical\nheterogeneities and avalanche-type relaxation associated to dynamic\nfacilitation, allowing us to relate the size distribution of heterogeneities to\ntheir time evolution. Within an avalanche, a local region relaxes multiple\ntimes, the more the larger is the avalanche. This property, related to the\nnature of the zero-temperature fixed point, directly leads to decoupling of\nparticle diffusion and relaxation time (the so-called Stokes-Einstein\nviolation). Our most salient predictions are tested and confirmed by numerical\nsimulations of scalar and tensorial thermal elasto-plastic models."
    },
    {
        "anchor": "Predicting the phase behavior of mixtures of active spherical particles: An important question in the field of active matter is whether or not it is\npossible to predict the phase behavior of these systems. Here, we study the\nphase coexistence of binary mixtures of torque-free active Brownian particles,\nfor both systems with purely repulsive interactions and systems with\nattractions. Using Brownian dynamics simulations, we show that phase\ncoexistences can be predicted quantitatively for these systems by measuring the\npressure and \"reservoir densities\". Specifically, in agreement with previous\nliterature, we find that the coexisting phases are in mechanical equilibrium,\ni.e. the two phases have the same pressure. Importantly, we also demonstrate\nthat the coexisting phases are in chemical equilibrium by bringing each phase\ninto contact with particle reservoirs, and showing that for each species these\nreservoirs are characterized by the same density for both phases. Using this\nrequirement of mechanical and chemical equilibrium we accurately construct the\nphase boundaries from properties which can be measured purely from the\nindividual coexisting phases. This result highlights that torque-free active\nBrownian systems follow simple coexistence rules, thus shedding new light on\ntheir thermodynamics.",
        "positive": "Phase Separation in Wetting Ridges of Sliding Drops on Soft and Swollen\n  Surfaces: Drops in contact with swollen, elastomeric substrates can induce a\ncapillary-mediated phase separation in wetting ridges. Using laser scanning\nconfocal microscopy, we visualize phase separation of oligomeric silicone oil\nfrom a crosslinked silicone network during steady-state sliding of water drops.\nWe find an inverse relationship between the oil tip height and the drop sliding\nspeed, which is rationalized by competing transport timescales of oil\nmolecules: separation rate and drop-advection speed. Separation rates in highly\nswollen networks are as fast as diffusion in pure melts."
    },
    {
        "anchor": "Solid-on-solid single block dynamics under mechanical vibration: The suppression of friction between sliding objects, modulated or enhanced by\nmechanical vibrations, is well established. However, the precise conditions of\noccurrence of these phenomena is not well understood. Here we address these\nquestions focusing on a simple spring--block model, which is relevant to\ninvestigate friction both at the atomistic as well as the macroscopic scale.\nThis allows to investigate the influence on friction of the properties of the\nexternal drive, of the geometry of the surfaces over which the block moves, and\nof the confining force. Via numerical simulations and a theoretical study of\nthe equations of motion we identify the conditions under which friction is\nsuppressed and/or recovered, and evidence the critical role played by surface\nmodulations and by the properties of the confining force.",
        "positive": "Time resolved viscoelastic properties during structural arrest and aging\n  of a colloidal glass: Evolution of the energy landscape during physical aging of glassy materials\ncan be understood from the frequency and strain dependence of the shear modulus\nbut the non-stationary nature of these systems frustrates investigation of\ntheir instantaneous underlying properties. Using a series of time dependent\nmeasurements we systematically reconstruct the frequency and strain dependence\nas a function of age for a repulsive colloidal glass undergoing structural\narrest. In this manner, we are able to unambiguously observe the structural\nrelaxation time, which increases exponentially with sample age at short times.\nThe yield stress varies logarithmically with time in the arrested state,\nconsistent with recent simulation results, whereas the yield strain is nearly\nconstant in this regime. Strikingly, the frequency dependence at fixed times\ncan be rescaled onto a master curve, implying a simple connection between the\naging of the system and the change in the frequency dependent modulus."
    },
    {
        "anchor": "Flagellar Dynamics of Chains of Active Janus Particles Fueled by an AC\n  electric field: We study the active dynamics of self-propelled asymmetrical colloidal\nparticles (Janus particles) fueled by an AC electric field. Both the speed and\nthe direction of the self-propulsion and the strength of attractive interaction\nbetween the particles can be controlled by tuning the frequency of the applied\nelectric field and the ion concentration of the solution. The strong attractive\nforce at high ion concentration give rise to chain formation of the Janus\nparticles, which can be explained by the quadrupolar charge distribution on the\nparticles. The chain formation is observed irrespective of the direction of the\nself-propulsion of the particles. When both the positions and the orientations\nof the heads of chains are fixed, they exhibit beating behavior reminiscent of\neukaryotic flagella. The beating frequency of the chains of the Janus particles\ndepends on the applied voltage and thus on the self-propulsive force. The\nscaling relation between the beating frequency and the self-propulsive force\ndeviates from theoretical predictions made previously on active filaments.\nHowever, this discrepancy is resolved by assuming that the attractive\ninteraction between the particles is mediated by the quadrupolar distribution\nof the induced charges, which gives indirect but convincing evidence on the\nmechanisms of the Janus particles. This signifies that the dependence between\nthe propulsion mechanism and the interaction mechanism, which had been\ndismissed previously, can modify dispersion relations of beating behaviors. In\naddition, hydrodynamic interaction within the chain and its effect on\npropulsion speed are discussed. These provide new insights on active filaments\nsuch as optimal flagellar design for biological functions.",
        "positive": "Density--nematic coupling in isotropic linear polymers: Linear polymers and other connected \"line liquids\" exhibit a coupling between\ndensity and equilibrium nematic order on the macroscopic level that gives rise\nto a Meyer-de Gennes vectorial conservation law. Nevertheless, isotropic linear\npolymer melts/solutions exhibit fluctuations of the density and of the nematic\norder that are not coupled by this vectorial constraint, just like for\nisotropic liquids composed of disconnected non-spherical particles. It takes\nthe proper tensorial description of the nematic order in linear polymer\nliquids, leading to a tensorial conservation law connecting density and\norientational order, that finally implicates coupled density and nematic order\nfluctuations, already in the isotropic system and not subject to the existence\nof an orientational phase transition. This coupling implies that a spatial\nvariation of density or a local concentration gradient will induce nematic\norder and thereby an acoustic or osmotic optical birefringence even in an\notherwise isotropic polymer melt/solution. We validate the theoretical\nconceptions by performing detailed Monte Carlo simulations of isotropic melts\nof \"soft\" worm-like chains with variable length and flexibility, and comparing\nthe numerically determined orientation correlation functions with predictions\nof the macroscopic theory. The methodology drawn sets forth a means of\ndetermining the macroscopic parameters by microscopic simulations to yield\nrealistic continuum models of specific polymeric materials."
    },
    {
        "anchor": "Orientational phase transitions in the hexagonal phase of a diblock\n  copolymer melt under shear flow: We generalize the earlier theory by Fredrickson [J. Rheol. v.38, 1045 (1994)]\nto study the orientational behaviour of the hexagonal phase of diblock\ncopolymer melt subjected to steady shear flow. We use symmetry arguments to\nshow that the orientational ordering in the hexagonal phase is a much weaker\neffect than in the lamellae. We predict the parallel orientation to be stable\nat low and the perpendicular orientation at high shear rates. Our analysis\nreproduces the experimental results by Tepe et al. [Macromolecules v.28, 3008\n(1995)] and explains the difficulties in experimental observation of the\ndifferent orientations in the hexagonal phase.",
        "positive": "Defect turbulence in a dense suspension of polar, active swimmers: We study the effects of inertia in dense suspensions of polar swimmers. The\nhydrodynamic velocity field and the polar order parameter field describe the\ndynamics of the suspension. We show that a dimensionless parameter $R$ (ratio\nof the swimmer self-advection speed to the active stress invasion speed)\ncontrols the stability of an ordered swimmer suspension. For $R$ smaller than a\nthreshold $R_1$, perturbations grow at a rate proportional to their wave number\n$q$. Beyond $R_1$, we show that the growth rate is $\\mathcal{O}(q^2)$ until a\nsecond threshold $R=R_2$ is reached. The suspension is stable for $R>R_2$. We\nperform direct numerical simulations to investigate the steady state properties\nand observe defect turbulence for $R<R_2$. An investigation of the spatial\norganisation of defects unravels a hidden transition: for small $R\\approx 0$\ndefects are uniformly distributed and cluster as $R\\to R_1$. Beyond $R_1$,\nclustering saturates and defects are arranged in nearly string-like structures."
    },
    {
        "anchor": "Surface response of spherical core-shell structured nanoparticle by\n  optically induced elastic oscillations of soft shell against hard core: The optically induced oscillatory response of a spherical two-component,\nshell-core structured, nanoparticle by nodeless elastic vibrations of soft\nperipheral shell against hard and dynamically immobile inner core is\nconsidered. The eigenfrequencies of the even-parity, spheroidal and odd-parity\ntorsional vibrational modes trapped in the finite-depth shell are obtained\nwhich are of practical interest for modal specification of individual\nresonances in spectra of resonant scattering of long wavelength electromagnetic\nwaves by ultrafine particles.",
        "positive": "Supersonic kinks and solitons in active solids: To show that steadily propagating nonlinear waves in active matter can be\ndriven internally, we develop a prototypical model of a topological kink moving\nwith a constant supersonic speed. We use a model of a bi-stable mass-spring\n(FPU) chain capable of generating active stress. In contrast to subsonic kinks\nin passive bi-stable chains, that are necessarily dissipative, the obtained\nsupersonic solutions are purely anti-dissipative. Our numerical experiments\npoint towards stability of the obtained kink-type solutions and the possibility\nof propagating kink-anti-kink bundles reminiscent of solitons. We show that\neven the simplest quasi-continuum approximation of the discrete model captures\nthe most important features of the predicted active phenomena."
    },
    {
        "anchor": "Analytical calculation of the Stokes drag of the spherical particle in a\n  nematic liquid crystal: As an approach to the motion of particles in an anisotropic liquid, we\nanalytically study the Stokes drag of spherical particles in a nematic liquid\ncrystal. The Stokes drag of spherical particles for a general anisotropic case\nis derived in terms of multipoles. In the case of weak anchoring, we use the\nwell-known distribution of the elastic director field around the spherical\nparticle. In the case of strong anchoring, the multipole expansion may be also\nused by modifying the size of a particle to the size of the deformation\ncoating. For the case of zero anchoring (uniform director field) we found that\nthe viscosities along the director $\\eta_{\\parallel}$ and perpendicular\ndirection $\\eta_{\\perp}$ are almost the same, which is quite reasonable because\nin this case the liquid behaves as isotropic. In the case of non-zero\nanchoring, the general ratio $\\eta_{\\parallel}/\\eta_{\\perp}$ is about 2 which\nis satisfied by experimental observations.",
        "positive": "A comparison of jamming behavior in systems composed of dimer- and\n  ellipse-shaped particles: We compare the structural and mechanical properties of static packings\ncomposed of frictionless convex (ellipses) and concave (rigid dimers) particles\nin two dimensions. We employ numerical simulations to generate static packings\nand measure the shear stress in response to applied simple shear strain as a\nfunction of the aspect ratio and amount of compression. We find that the\nbehavior near jamming is significantly different for ellipses and dimers even\nthough both shapes are roughly characterized by the aspect ratio and possess\nthe same number of translational and rotational degrees of freedom per\nparticle. For example, we find that ellipse packings are hypostatic (not\nisostatic as found for dimers), display novel power-law scaling of the static\nlinear shear modulus and contact number with the amount of compression, and\npossess stress-strain relations that are qualitatively different from that for\ndimers. Thus, we observe that important macroscopic properties of static\npackings of anisotropic particles can depend on the microscale geometrical\nfeatures of individual particles."
    },
    {
        "anchor": "Instabilities and turbulence-like dynamics in an oppositely driven\n  binary particle mixture: Using extensive particle-based simulations, we investigate out-of-equilibrium\npattern dynamics in an oppositely driven binary particle system in two\ndimensions. A surprisingly rich dynamical behavior including lane formation,\njamming, oscillation and turbulence-like dynamics is found. The ratio of two\nfriction coefficients is a key parameter governing the stability of lane\nformation. When the friction coefficient transverse to the external force\ndirection is sufficiently small compared to the longitudinal one, the lane\nstructure becomes unstable to shear-induced disturbances, and the system\neventually exhibits a dynamical transition into a novel turbulence-like phase\ncharacterized by random convective flows. We numerically construct an\nout-of-equilibrium phase diagram. Statistical analysis of complex\nspatio-temporal dynamics of the fully nonlinear turbulence-like phase suggests\nits apparent reminiscence to the swarming dynamics in certain active matter\nsystems.",
        "positive": "Hydrodynamic interactions hinder transport of flow-driven colloidal\n  particles: The flow-driven transport of interacting micron-sized particles occurs in\nmany soft matter systems spanning from the translocation of proteins to moving\nemulsions in microfluidic devices. Here we combine experiments and theory to\ninvestigate the collective transport properties of colloidal particles along a\nrotating ring of optical traps. In the co-rotating reference frame, the\nparticles are driven by a vortex flow of the surrounding fluid. When increasing\nthe depth of the optical potential, we observe a jamming behavior that\nmanifests itself in a strong reduction of the current with increasing particle\ndensity. We show that this jamming is caused by hydrodynamic interactions that\nenhance the energetic barriers between the optical traps. This leads to a\ntransition from an over- to an under-critical tilting of the potential in the\ncorotating frame. Based on analytical considerations, the enhancement effect is\nestimated to increase with increasing particle size or decreasing radius of the\nring of traps. Measurements for different ring radii and Stokesian dynamics\nsimulations for corresponding particle sizes confirm this. The enhancement of\npotential barriers in the flow-driven system is contrasted to the reduction of\nbarriers in a force-driven one. This diverse behavior demonstrates that\nhydrodynamic interactions can have a very different impact on the collective\ndynamics of many-body systems. Applications to soft matter and biological\nsystems require careful consideration of the driving mechanism and of the role\nof hydrodynamic interactions."
    },
    {
        "anchor": "Variational Inequalities in Critical-State Problems: Similar evolutionary variational inequalities appear as convenient\nformulations for continuous quasistationary models for sandpile growth,\nformation of a network of lakes and rivers, magnetization of type-II\nsuperconductors, and elastoplastic deformations. We outline the main steps of\nsuch models derivation and try to clarify the origin of this similarity. New\ndual variational formulations, analogous to mixed variational inequalities in\nplasticity, are derived for sandpiles and superconductors.",
        "positive": "Enhancing nanoparticle diffusion on a unidirectional domain wall\n  magnetic ratchet: The performance of nanoscale magnetic devices is often limited by the\npresence of thermal fluctuations, while in micro-nanofluidic applications the\nsame fluctuations may be used to spread reactants or drugs. Here we demonstrate\nthe controlled motion and the enhancement of diffusion of magnetic\nnanoparticles that are manipulated and driven across a series of Bloch walls\nwithin an epitaxially grown ferrite garnet film. We use a rotating magnetic\nfield to generate a traveling wave potential that unidirectionally transports\nthe nanoparticles at a frequency tunable speed. Strikingly, we find an\nenhancement of diffusion along the propulsion direction and a frequency\ndependent diffusion coefficient that can be precisely controlled by varying the\nsystem parameters. To explain the reported phenomena, we develop a theoretical\napproach that shows a fair agreement with the experimental data enabling an\nexact analytical expression for the enhanced diffusivity above the magnetically\nmodulated periodic landscape. Our technique to control thermal fluctuations of\ndriven magnetic nanoparticles represents a versatile and powerful way to\nprogrammably transport magnetic colloidal matter in a fluid, opening the doors\nto different fluidic applications based on exploiting magnetic domain wall\nratchets."
    },
    {
        "anchor": "Computer simulations of colloidal gels: how hindered particle rotation\n  affects structure and rheology: The effects of particle roughness and short-ranged non-central forces on\ncolloidal gels are studied using computer simulations in which particles\nexperience a sinusoidal variation in energy as they rotate. The number of\nminima $n$ and energy scale $K$ are the key parameters; for large $K$ and $n$,\nparticle rotation is strongly hindered, but for small $K$ and $n$ particle\nrotation is nearly free. A series of systems are simulated and characterized\nusing fractal dimensions, structure factors, coordination number distributions,\nbond-angle distributions and linear rheology. When particles rotate easily,\nclusters restructure to favor dense packings. This leads to longer gelation\ntimes and gels with strand-like morphology. The elastic moduli of such gels\nscale as $G' \\propto \\omega^{0.5}$ at high shear frequencies $\\omega$. In\ncontrast, hindered particle rotation inhibits restructuring and leads to rapid\ngelation and diffuse morphology. Such gels are stiffer, with\n$G'\\propto\\omega^{0.35}$. The viscous moduli $G''$ in the low-barrier and\nhigh-barrier regimes scale according to exponents $0.53$ and $0.5$,\nrespectively. The crossover frequency between elastic and viscous behaviors\ngenerally increases with the barrier to rotation. These findings agree\nqualitatively with some recent experiments on heterogeneously-surface particles\nand with studies of DLCA-type gels and gels of smooth spheres.",
        "positive": "Double Phase Transitions in Magnetized Spinor Bose-Einstein Condensation: It is investigated theoretically that magnetized Bose-Einstein condensation\n(BEC) with the internal (spin) degrees of freedom exhibits a rich variety of\nphase transitions, depending on the sign of the interaction in the spin\nchannel. In the antiferromagnetic interaction case there exist always double\nBEC transitions from single component BEC to multiple component BEC. In the\nferromagnetic case BEC becomes always unstable at a lower temperature, leading\nto a phase separation. The detailed phase diagram for the temperature vs the\npolarization, the spatial spin structure, the distribution of non-condensates\nand the excitation spectrum are examined for the harmonically trapped systems."
    },
    {
        "anchor": "Correlated particle dynamics in concentrated quasi-two-dimensional\n  suspensions: We investigate theoretically and experimentally how the hydrodynamically\ncorrelated lateral motion of particles in a suspension confined between two\nsurfaces is affected by the suspension concentration. Despite the long range of\nthe correlations (decaying as 1/r^2 with the inter-particle distance r), the\nconcentration effect is present only at short inter-particle distances for\nwhich the static pair correlation is nonuniform. This is in sharp contrast with\nthe effect of hydrodynamic screening present in unconfined suspensions, where\nincreasing the concentration changes the prefactor of the large-distance\ncorrelation.",
        "positive": "Thermal fluctuations of an interface near a contact line: The effect of thermal fluctuations near a contact line of a liquid interface\npartially wetting an impenetrable substrate is studied analytically and\nnumerically. Promoting both the interface profile and the contact line position\nto random variables, we explore the equilibrium properties of the corresponding\nfluctuating contact line problem based on an interfacial Hamiltonian involving\na \"contact\" binding potential. To facilitate an analytical treatment we\nconsider the case of a one-dimensional interface. The effective boundary\ncondition at the contact line is determined by a dimensionless parameter that\nencodes the relative importance of thermal energy and substrate energy at the\nmicroscopic scale. We find that this parameter controls the transition from a\npartially wetting to a pseudo-partial wetting state, the latter being\ncharacterized by a thin prewetting film of fixed thickness. In the partial\nwetting regime, instead, the profile typically approaches the substrate via an\nexponentially thinning prewetting film. We show that, independently of the\nphysics at the microscopic scale, Young's angle is recovered sufficiently far\nfrom the substrate. The fluctuations of the interface and of the contact line\ngive rise to an effective disjoining pressure, exponentially decreasing with\nheight. Fluctuations therefore provide a regularization of the singular contact\nforces occurring in the corresponding deterministic problem."
    },
    {
        "anchor": "Effective temperature of active complex matter: We use molecular dynamics simulations to study the dynamics of an ensemble of\ninteracting self-propelled semi-flexible polymers in contact with a thermal\nbath. Our intention is to model complex systems of biological interest. We find\nthat an effective temperature allows one to rationalize the out of equilibrium\ndynamics of the system. This parameter is measured in several independent ways\n-- from fluctuation-dissipation relations and by using tracer particles -- and\nthey all yield equivalent results. The effective temperature takes a higher\nvalue than the temperature of the bath when the effect of the motors is not\ncorrelated with the structural rearrangements they induce. We show how to use\nthis concept to interpret experimental results and suggest possible innovative\nresearch directions.",
        "positive": "Sliding periodic boundary conditions for lattice Boltzmann and lattice\n  kinetic equations: We present a method to impose linear shear flow in discrete-velocity kinetic\nmodels of hydrodynamics through the use of sliding periodic boundary\nconditions. Our method is derived by an explicit coarse-graining of the\nLees-Edwards boundary conditions for Couette flow in molecular dynamics,\nfollowed by a projection of the resulting equations onto the subspace spanned\nby the discrete velocities of the lattice Boltzmann method. The boundary\nconditions are obtained without resort to perturbative expansions or\nmodifications of the discrete velocity equilibria, allowing our method to be\napplied to a wide class of lattice Boltzmann models. Our numerical results for\nthe sheared hydrodynamics of a one-component isothermal fluid show excellent\nagreement with analytical results, while for a two-component fluid the results\nshow a clear improvement over previous methods for introducing Lees-Edwards\nboundary conditions into lattice Boltzmann. Using our method, we obtain a\ndynamical steady state in a sheared spinodally decomposing two-dimensional\nfluid, under conditions where previous methods give spurious finite-size\nartifacts."
    },
    {
        "anchor": "Inelastic collapse in one-dimensional driven systems under gravity: We study the inelastic collapse in the one-dimensional $N$-particle systems\nin the situation where the system is driven from below under the gravity. We\ninvestigate the hard-sphere limit of the inelastic soft-sphere systems by\nnumerical simulations to find how the collision rate per particle $n_{coll}$\nincreases as a function of the elastic constant of the sphere $k$ when the\nrestitution coefficient $e$ is kept constant. For the systems with large enough\n$N \\agt 20$, we find three regimes in $e$ depending on the behavior of\n$n_{coll}$ in the hard-sphere limit: (i) uncollapsing regime for $1 \\ge e >\ne_{c1}$, where $n_{coll}$ converges to a finite value, (ii) logarithmically\ncollapsing regime for $e_{c1} > e > e_{c2}$, where $n_{coll}$ diverges as\n$n_{coll} \\sim \\log k$, and (iii) power-law collapsing regime for $e_{c2} > e >\n0$, where $n_{coll}$ diverges as $n_{coll} \\sim k^\\alpha$ with an exponent\n$\\alpha$ that depends on $N$. The power-law collapsing regime shrinks as $N$\ndecreases and seems not to exist for the system with N=3 while, for large $N$,\nthe size of the uncollapsing and the logarithmically collapsing regime\ndecreases as $e_{c1} \\simeq 1-2.6/N$ and $e_{c2} \\simeq 1-3.0/N$. We\ndemonstrate that this difference between large and small systems exists already\nin the inelastic collapse without the external drive and the gravity.",
        "positive": "Viscosity of Suspensions of Hard and Soft Spheres: From a reanalysis of the published literature, the low-shear viscosity of\nsuspensions of hard spheres is shown to have a dynamic crossover in its\nconcentration dependence, from a stretched exponential at lower concentrations\nto a power law at elevated concentrations. The crossover is sharp, with no\ntransition region in which neither form applies, and occurs at a volume\nfraction (ca. 0.41) and relative viscosity (ca. 11) well below the sphere\nvolume fraction and relative viscosity (0.494, 49, respectively) of the lower\nphase boundary of the hard sphere melting transition. For soft spheres --\ntaking many-arm star polymers as a model -- with increasing sphere hardness\n$\\eta(\\phi)$ shows a crossover from random-coil polymer behavior toward the\nbehavior shown by true hard spheres."
    },
    {
        "anchor": "Kinetic theory of discontinuous shear thickening: A simple kinetic theory to exhibit a discontinuous shear thickening (DST) is\nproposed. The model includes the collision integral and the friction from\nenvironment as well as a thermostat term characterized by $T_{\\rm ex}$. The\nviscosity of this model is proportional to $\\dot\\gamma^2$ for large shear rate\n$\\dot\\gamma$, while it is Newtonian for low $\\dot\\gamma$. The emergence of the\nDST is enhanced for lower density and lower nonzero $T_{\\rm ex}$.",
        "positive": "Spontaneous flow created by active topological defects: Topological defects are at the root of the large-scale organization of liquid\ncrystals. In two-dimensional active nematics, two classes of topological\ndefects of charges $\\pm 1/2$ are known to play a major role due to active\nstresses. Despite this importance, few analytical results have been obtained on\nthe flow-field and active-stress patterns around active topological defects.\nUsing the generic hydrodynamic theory of active systems, we investigate the\nflow and stress patterns around these topological defects in unbounded,\ntwo-dimensional active nematics. Under generic assumptions, we derive\nanalytically the spontaneous velocity and stall force of self-advected defects\nin the presence of both shear and rotational viscosities. Applying our\nformalism to the dynamics of monolayers of elongated cells at confluence, we\nshow that the non-conservation of cell number generically increases the\nself-advection velocity and could provide an explanation for their observed\nrole in cellular extrusion and multilayering. We finally investigate\nnumerically the influence of the Ericksen stress. Our work paves the way to a\ngeneric study of the role of topological defects in active nematics, and in\nparticular in monolayers of elongated cells."
    },
    {
        "anchor": "Analytical Form of Forces in Hydrophobic Collapse: We calculate analytically the forces between two solvophobic solutes,\nconsidering a model system. We show that the effective interaction forces\nbetween two solvophobic solutes, mediated by the solvent, is attractive for\nshort ranges, which decreases linearly with surface-to-surface separation s\nbetween the solutes and repulsive in the long range falling off as 1 / s 4 .\nThe attraction originates from the unbalanced Laplace force at the liquid-gas\ninterface, generated by the repulsive interaction with the solvent particles,\naround the solutes at small s. The long range part arises due to unbalanced\nosmotic pressure. We illustrate the calculations for the Lennard-Jones solvent.\nWe discuss the general implication of our results in the context of hydrophobic\ncollapse.",
        "positive": "Electrostatics in the Stability and Misfolding of the Prion Protein:\n  Salt Bridges, Self-Energy, and Solvation: Using a recently developed mesoscopic theory of protein dielectrics, we have\ncalculated the salt bridge energies, total residue electrostatic potential\nenergies, and transfer energies into a low dielectric amyloid-like phase for 12\nspecies and mutants of the prion protein. Salt bridges and self energies play\nkey roles in stabilizing secondary and tertiary structural elements of the\nprion protein. The total electrostatic potential energy of each residue was\nfound to be invariably stabilizing. Residues frequently found to be mutated in\nfamilial prion disease were among those with the largest electrostatic\nenergies. The large barrier to charged group desolvation imposes regional\nconstraints on involvement of the prion protein in an amyloid aggregate,\nresulting in an electrostatic amyloid recruitment profile that favours regions\nof sequence between alpha helix 1 and beta strand 2, the middles of helices 2\nand 3, and the region N-terminal to alpha helix 1. We found that the\nstabilization due to salt bridges is minimal among the proteins studied for\ndisease-susceptible human mutants of prion protein."
    },
    {
        "anchor": "Effects of topological constraints on globular polymers: Topological constraints can affect both equilibrium and dynamic properties of\npolymer systems, and can play a role in the organization of chromosomes.\nDespite many theoretical studies, the effects of topological constraints on the\nequilibrium state of a single compact polymer have not been systematically\nstudied. Here we use simulations to address this longstanding problem. We find\nthat sufficiently long unknotted polymers differ from knotted ones in the\nspatial and topological states of their subchains. The unknotted globule has\nsubchains that are mostly unknotted and form asymptotically compact $R_G(s)\n\\sim s^{1/3}$ crumples. However, crumples display high fractal dimension of the\nsurface $d_b = 2.8$, forming excessive contacts and interpenetrating each\nother. We conclude that this topologically constrained equilibrium state\nresembles a conjectured crumpled globule [Grosberg et al., Journal de Physique,\n1988, 49, 2095], but differs from its idealized hierarchy of self-similar,\nisolated and compact crumples.",
        "positive": "Revisiting ignited-quenched transition and the non-Newtonian rheology of\n  a sheared dilute gas-solid suspension: The hydrodynamics and rheology of a sheared dilute gas-solid suspension,\nconsisting of inelastic hard-spheres suspended in a gas, are analysed using\nanisotropic Maxwellian as the single particle distribution function. The\nclosed-form solutions for granular temperature and three invariants of the\nsecond-moment tensor are obtained as functions of the Stokes number ($St$), the\nmean density ($\\nu$) and the restitution coefficient ($e$). Multiple states of\nhigh and low temperatures are found when the Stokes number is small, thus\nrecovering the \"ignited\" and \"quenched\" states, respectively, of Tsao \\& Koch\n(J. Fluid Mech.,1995). The phase diagram is constructed in the\nthree-dimensional ($\\nu, St, e$)-space that delineates the regions of ignited\nand quenched states and their coexistence. Analytical expressions for the\nparticle-phase shear viscosity and the normal stress differences are obtained,\nalong with related scaling relations on the quenched and ignited states. At any\n$e$, the shear-viscosity undergoes a discontinuous jump with increasing shear\nrate (i.e.~ discontinuous shear-thickening) at the \"quenched-ignited\"\ntransition. The first (${\\mathcal N}_1$) and second (${\\mathcal N}_2$)\nnormal-stress differences also undergo similar first-order transitions: (i)\n${\\mathcal N}_1$ jumps from large to small positive values and (ii) ${\\mathcal\nN}_2$ from positive to negative values with increasing $St$, with the\nsign-change of ${\\mathcal N}_2$ identified with the system making a transition\nfrom the quenched to ignited states. The superior prediction of the present\ntheory over the standard Grad's method and the Chapman-Enskog solution is\ndemonstrated via comparisons of transport coefficients with simulation data for\na range of Stokes number and restitution coefficient."
    },
    {
        "anchor": "Hidden hierarchy in the rheology of dense suspensions: Dense suspensions of fine particles are significant in numerous biological,\nindustrial, and natural phenomena. They also provide an ideal tool to develop\nstatistical mechanics description for out-of-equilibrium systems. Predicting\nthe bulk response of such materials has been challenging since these systems\noften undergo liquid-solid transitions upon a small change in solid\nconcentration or applied loading. Developing an understanding of the mechanisms\nthat drive these phenomena has over the last several years led to a surge in\nresearch activity at the intersection of fluid mechanics, granular materials,\ndriven disordered systems, tribology, and soft condensed matter physics. One\ncentral aspect that emerged is that these phenomena are due to a\nshear-activated or deactivated network of contacts between particles. The\nperspective briefly presents the current state of understanding and challenges\nassociated with relating the flow of material at the bulk scale with the\nmicroscopic physics at the particle scale.",
        "positive": "Interaction between substrate and probe in liquid metal Ga: Experimental\n  and theoretical analysis: Understanding the interaction between two bodies in a liquid metal is\nimportant for developing metals with high stiffness, strength, plasticity, and\nthermal stability. We conducted atomic force microscopy measurements in liquid\nGa and performed a theoretical calculation in which the statistical mechanics\nof a simple liquid containing a quantum effect was used. The experiment and\ntheory showed unusual behaviours in the interactions between the probe and\nsubstrate in the liquid metal. In the interactions, there were relatively\nnumerous oscillations and large amplitudes. Furthermore, the interaction ranges\nwere relatively long. From the theoretical calculations, we found an asymmetric\nproperty that when the probe is solvophilic and the substrate is solvophobic,\nthe interaction tends to be repulsive; when the solvation affinities are\nexchanged, the interaction tends to be attractive in the close position. Our\nfindings will be useful for understanding and controlling dispersion\nstabilities of nanoparticles and chemical reactions in liquid metals."
    },
    {
        "anchor": "On the use of magnetic particles to enhance the flow of vibrated grains\n  through narrow apertures: The flow of grains through narrow apertures posses an extraordinary\nchallenge: clogging. Strategies to alleviate the effect of clogging, such as\nthe use of external vibration, are always part of the design of machinery for\nthe handling of bulk materials. It has recently been shown that one way to\nreduce clogging is to use a small fraction of small particles as an additive.\nBesides, several works reported that self-repelling magnetic grains can flow\nthrough narrow apertures with little clogging, which suggest these are\nexcellent candidates as \"lubricating\" additives for other granular materials.\nIn this work, we study the effect of adding self-repelling magnetic particles\nto a sample of grains in two-dimensions. We find that, in contrast with\nintuition, the added magnetic grains not necessarily aid the flow of the\noriginal species.",
        "positive": "Wave-induced motion of magnetic spheres: We report an experimental study of the motion of magnetized beads driven by a\ntravelling wave magnetic field. For sufficiently large wave speed, we report\nthe existence of a backward motion, in which the sphere can move in the\ndirection opposite to the driving wave. We show that the transition to this new\nstate is strongly subcritical and can lead to chaotic motion of the bead. For\nsome parameters, this counter-propagation of the sphere can be one order of\nmagnitude faster than the driving wave speed. These results are understood in\nthe framework of a model based on the interplay among solid friction, air\nresistance and magnetic torque."
    },
    {
        "anchor": "Integral equation for inhomogeneous condensed bosons generalizing the\n  Gross-Pitaevskii differential equation: We give here the derivation of a Gross-Pitaevskii--type equation for\ninhomogeneous condensed bosons. Instead of the original Gross-Pitaevskii\ndifferential equation, we obtain an integral equation that implies less\nrestrictive assumptions than are made in the very recent study of Pieri and\nStrinati [Phys. Rev. Lett. 91 (2003) 030401]. In particular, the Thomas-Fermi\napproximation and the restriction to small spatial variations of the order\nparameter invoked in their study are avoided.",
        "positive": "Gas-Solid Coexistence in Highly Charged Colloidal Suspensions: Aqueous suspensions of highly charged polystyrene particles with different\nvolume fractions have been investigated for structural ordering and phase\nbehavior using static light scattering (SLS) and confocal laser scanning\nmicroscope (CLSM). Under deionized conditions, suspensions of high charge\ndensity colloidal particles remained disordered whereas suspensions of\nrelatively low charge density showed crystallization by exhibiting iridescence\nfor the visible light. Though for unaided eye crystallized suspensions appeared\nhomogeneous, static light scattering measurements and CLSM observations have\nrevealed their inhomogeneous nature in the form of coexistence of voids with\ndense ordered regions. CLSM investigations on disordered suspensions showed\ntheir inhomogeneous nature in the form coexistence of voids with dense\ndisordered (amorphous) regions. Our studies on highly charged colloids confirm\nthe occurrence of gas-solid transition and are in accordance with predictions\nof Monte Carlo simulations using a pair-potential having a long-range\nattractive term [Mohanty and Tata, Journal of Colloid and Interface Science\n2003, 264, 101]. Based on our experimental and simulation results we argue that\nthe reported reentrant disordered state [Yamanaka et al Phys. Rev. Lett. 1998,\n80, 5806 and Toyotama et al Langmuir, 2003, 19, 3236] in charged colloids\nobserved at high charge densities is a gas-solid coexistence state."
    },
    {
        "anchor": "Magnetization Plateaus of a Double Fullerene Core/Shell\n  Like-Nanostructure in an External Magnetic Field: Monte Carlo Study: This paper concerns the investigation of the critical (HC) and the saturation\n(HS) magnetic fields behavior of the studied system as a function of different\nphysical parameters. The Monte Carlo method has been used to study the magnetic\nproperties of a ferrimagnetic behavior of a double fullerene X60 core/shell\nlike-nanostructure, where the symbol X can be assigned to any magnetic atom.\nBased on the Ising model, we focus our study on a system formed by a double\nsphere core/shell. The two spheres are containing the spins: $\\sigma=\\pm 1/2$\nin the core are surrounded by the spin $S=\\pm 1, 0$ in the shell. Many types of\nmagnetization curves have been found, depending on the competitions among the\nexchange couplings, the crystal fields and the temperature.",
        "positive": "Collective dynamics of soft active particles: We present a model of soft active particles that leads to a rich array of\ncollective behavior found also in dense biological swarms of bacteria and other\nunicellular organisms. Our model uses only local interactions, such as\nVicsek-type nearest neighbor alignment, short-range repulsion, and a local\nboundary term. Changing the relative strength of these interactions leads to\nmigrating swarms, rotating swarms and jammed swarms, as well as swarms that\nexhibit run-and-tumble motion, alternating between migration and either\nrotating or jammed states. Interestingly, although a migrating swarm moves\nslower than an individual particle, the diffusion constant can be up to three\norders of magnitude larger, suggesting that collective motion can be highly\nadvantageous, for example, when searching for food."
    },
    {
        "anchor": "Limiting the valence: advancements and new perspectives on patchy\n  colloids, soft functionalized nanoparticles and biomolecules: Limited bonding valence, usually accompanied by well-defined directional\ninteractions and selective bonding mechanisms, is nowadays considered among the\nkey ingredients to create complex structures with tailored properties: even\nthough isotropically interacting units already guarantee access to a vast range\nof functional materials, anisotropic interactions can provide extra\ninstructions to steer the assembly of specific architectures. The anisotropy of\neffective interactions gives rise to a wealth of self-assembled structures both\nin the realm of suitably synthesized nano- and micro-sized building blocks and\nin nature, where the isotropy of interactions is often a zero-th order\ndescription of the complicated reality. In this review, we span a vast range of\nsystems characterized by limited bonding valence, from patchy colloids of new\ngeneration to polymer-based functionalized nanoparticles, DNA-based systems and\nproteins, and describe how the interaction patterns of the single building\nblocks can be designed to tailor the properties of the target final structures.",
        "positive": "Inter-molecular structure factors of macromolecules in solution:\n  integral equation results: The inter-molecular structure of semidilute polymer solutions is studied\ntheoretically. The low density limit of a generalized Ornstein-Zernicke\nintegral equation approach to polymeric liquids is considered. Scaling laws for\nthe dilute-to-semidilute crossover of random phase (RPA) like structure are\nderived for the inter-molecular structure factor on large distances when\ninter-molecular excluded volume is incorporated at the microscopic level. This\nleads to a non-linear equation for the excluded volume interaction parameter.\nFor macromolecular size-mass scaling exponents, $\\nu$, above a\nspatial-dimension dependent value, $\\nu_c=2/d$, mean field like density scaling\nis recovered, but for $\\nu<\\nu_c$ the density scaling becomes non-trivial in\nagreement with field theoretic results and justifying phenomenological\nextensions of RPA. The structure of the polymer mesh in semidilute solutions is\ndiscussed in detail and comparisons with large scale Monte Carlo simulations\nare added. Finally a new possibility to determine the correction to scaling\nexponent $\\omega_{12}$ is suggested."
    },
    {
        "anchor": "Electron-positron interaction in light elements represented by atoms\n  embedded in an electron gas: Mijnarends et al. [J. Phys. Condens. Matter {\\bf 10}, 10383 (1998)] contested\nthe best existing calculations of positron annihilation rates in jellium and\ncrystal lattices, pointing in this way at deficiencies of existing theories of\nelectron-positron interaction in these materials. In the present work the local\nenhancement factors due to positron-electron interaction in Li, Be, B, C, N and\nO are computed in a consequent many-body approach for core and as concerns\nlithium also for conduction electrons and compared to the results of existing\napproximations to this problem which avoid direct many-body calculations in\nmetals, i.e. the local density, generalized gradient and weighted density\napproximations, as well as to experimental data. Conclusions about positron\nlifetime and positron-electron correlation energy are also presented.\nSuggestions concerning annihilation rates in an electron gas agree with those\nof Mijnarends et al.",
        "positive": "Functional colloidal micro-sieves assembled and guided above a\n  channel-free magnetic striped film: Colloidal inclusions in lab-on-a-chip devices can be used to perform analytic\noperations in a non-invasive fashion. We demonstrate here a novel approach to\nrealize fast and reversible micro-sieving operations by manipulating and\ntransporting colloidal chains via mobile domain walls in a magnetic structured\nsubstrate. We show that this technique allows to precisely move and sieve\nnon-magnetic particles, to tweeze microscopic cargos or to mechanically\ncompress highly dense colloidal monolayers."
    },
    {
        "anchor": "Isotropic-nematic phase equilibria in the Onsager theory of hard rods\n  with length polydispersity: We analyse the effect of a continuous spread of particle lengths on the phase\nbehavior of rodlike particles, using the Onsager theory of hard rods. Our aim\nis to establish whether ``unusual'' effects such as isotropic-nematic-nematic\n(I-N-N) phase separation can occur even for length distributions with a single\npeak. We focus on the onset of I-N coexistence. For a log-normal distribution\nwe find that a finite upper cutoff on rod lengths is required to make this\nproblem well-posed. The cloud curve, which tracks the density at the onset of\nI-N coexistence as a function of the width of the length distribution, exhibits\na kink; this demonstrates that the phase diagram must contain a three-phase\nI-N-N region.\n  Theoretical analysis shows that in the limit of large cutoff the cloud point\ndensity actually converges to zero, so that phase separation results at any\nnonzero density; this conclusion applies to all length distributions with\nfatter-than-exponentail tails. Finally we consider the case of a Schulz\ndistribution, with its exponential tail. Surprisingly, even here the long rods\n(and hence the cutoff) can dominate the phase behaviour, and a kink in the\ncloud curve and I-N-N coexistence again result. Theory establishes that there\nis a nonzero threshold for the width of the length distribution above which\nthese long rod effects occur, and shows that the cloud and shadow curves\napproach nonzero limits for large cutoff, both in good agreement with the\nnumerical results.",
        "positive": "Modeling growing confluent tissues using a lattice Boltzmann method:\n  interface stability and fluctuations: Tissue growth underpins a wide array of biological and developmental\nprocesses, and numerical modeling of growing systems has been shown to be a\nuseful tool for understanding these processes. However, the phenomena that can\nbe captured are often limited by the size of systems that can be modeled. Here,\nwe address this limitation by introducing a Lattice-Boltzmann method (LBM) for\na growing system that is able to efficiently model hydrodynamic length-scales.\nThe model incorporates a novel approach to describing the growing front of a\ntissue, which we use to investigate the dynamics of the interface of growing\nmodel tissues. We find that the interface grows with scaling in agreement with\nthe Kardar-Parisi-Zhang (KPZ) universality class when growth in the system is\nbulk driven. Interestingly, we also find the emergence of a previously\nunreported hydrodynamic instability when proliferation is restricted to the\ntissue edge. We then develop an analytical theory to show that the instability\narises due to a coupling between the number of cells actively proliferating and\nthe position of the interface."
    },
    {
        "anchor": "Photo-Switchable Surfactants for Responsive Air-Water Interfaces: Azo\n  vs. Arylazopyrazole Amphiphiles: Arylazopyrazoles (AAPs) as substitutes for azo derivatives have gained\nconsiderable attention due to their superior properties offering E/Z\nphoto-isomerization with high yield. In order to compare and quantify their\nperformance, azobenzene tetraethylammonium (Azo-TB) and arylazopyrazole\ntetraethylammonium (AAP-TB) bromides were synthesized and characterized in the\nbulk (water) using NMR spectroscopy. At the air-water interface complementary\ninformation from vibrational sum-frequency generation (SFG) spectroscopy and\nneutron reflectometry (NR) has revealed the effects of E/Z isomerization in\ngreat detail. In bulk water the photostationary states of >89% for E/Z\nswitching in both directions were very similar for the surfactants, while their\ninterfacial behavior was substantially different. In particular, the surface\nexcess $\\Gamma$ of the surfactants changed drastically between E/Z isomers for\nAAP-TB (maximum change of $\\Gamma$: 2.15 $\\mu$mol/m$^2$); for Azo-TB the change\nwas only moderate (maximum change of $\\Gamma$: 1.02 $\\mu$mol/m$^2$). Analysis\nof SFG spectra revealed that strong non-resonant contributions that heterodyned\nthe resonant vibrational bands were proportional to $\\Gamma$, enabling the\naromatic C-H band to be interpreted as an indicator for changes in interfacial\nmolecular order. Close comparison of $\\Gamma$ from NR with the SFG amplitude\nfrom the aromatic C-H stretch as a function of concentrations and E/Z\nconformation revealed substantial molecular order changes for AAP-TB. In\ncontrast, only $\\Gamma$ and not the molecular order varied for Azo-TB. These\ndifferences in interfacial properties are attributed to the molecular structure\nof the AAP center that enables favorable lateral interactions at the air-water\ninterface, causing closed-packed interfacial layers and substantial changes\nduring E/Z photo-isomerization.",
        "positive": "Mechanism of Structural Colors in Binary Mixtures of Nanoparticle-based\n  Supraballs: Inspired by structural colors in avian species, various synthetic strategies\nhave been developed to produce non-iridescent, saturated colors using\nnanoparticle assemblies. Mixtures of nanoparticles varying in particle\nchemistry (or complex refractive indices) and particle size have additional\nemergent properties that impact the color produced. For such complex\nmulti-component systems, an understanding of assembled structure along with a\nrobust optical modeling tool can empower scientists to perform intensive\nstructure-color relationship studies and fabricate designer materials with\ntailored color. Here, we demonstrate how we can reconstruct the assembled\nstructure from small-angle scattering measurements using the computational\nreverse-engineering analysis for scattering experiments (CREASE) method and\nthen use the reconstructed structure in finite-difference time-domain (FDTD)\ncalculations to predict color. We successfully, quantitatively predict\nexperimentally observed color in mixtures containing strongly absorbing melanin\nnanoparticles and demonstrate the influence of a single layer of segregated\nnanoparticles on color produced. The versatile computational approach presented\nin this work is useful for engineering synthetic materials with desired colors\nwithout laborious trial and error experiments."
    },
    {
        "anchor": "Empirical Potential Structure Refinement of semi-crystalline polymer\n  systems: polytetrafluoroethylene and polychlorotrifluoroethylene: Empirical potential structure refinement (EPSR) simulations are performed on\ntotal neutron scattering data from powder samples of polytetrafluoroethylene\n(PTFE) and polychlorotrifluoroethylene (PCTFE), both at 300K. For PTFE a number\nof Bragg peaks are visible in the scattering data and these are found to be\nconsistent with a lattice spacing $a(=b)=5.69(1)$\\AA\\ with a dihedral angle\nalong the (helical) chain of 166$^\\circ$ which gives a repeat distance along\nthe chain (c-axis) of $\\sim$19.6\\AA. The positions of the Bragg peaks are well\nreproduced by this model, although there is a mismatch in the amplitudes of\nsome of the higher order reflections between simulation and data. For PCTFE\nthere is only one visible Bragg peak (100) which is well reproduced by a\nhexagonal lattice of atactic parallel polymers with a spacing of\n$a(=b)=6.37(1)$\\AA. In this case the absence of distinct reflections along the\npolymer c-axis makes characterisation of the internal dihedral angle difficult,\nbut a model with nearly straight \\textit{trans} (zig-zag) structure gives best\nagreement with the data. For PCTFE little change in structure could be\ndiscerned when the material was heated to 550K, apart from a slight increase in\nlattice spacing. In both cases there is substantial diffuse scattering between\nthe Bragg peaks, and this is correctly replicated by the EPSR simulations.",
        "positive": "Kinetics and steady state of polar flock with birth and death: We study a collection of polar self-propelled particles or polar flock on a\ntwo dimensional substrate with birth and death. Most of the previous studies of\npolar flock with birth and death have assumed the compressible flock, such that\nthe local density of flock is completely ignored. Effect of birth and death of\nparticles on the flock with moderate density is focus of our study. System is\nmodeled using coarse-grained hydrodynamic equations of motion for local density\nand velocity of the flock and solved using numerical integration of the\nnonlinear coupled partial differential equations of motion and linearised\nhydrodynamics about the broken symmetry state. We studied the ordering kinetics\nas well as the steady state properties of the immortal flock and flock with\nfinite birth and death rate. The ordering kinetics of the velocity field\nremains unaffected whereas the density field shows a crossover from asymptotic\ngrowth exponent $5/6$ for the immortal flock to diffusive limit $1/3$ for large\nbirth and death rates. In the steady state, the presence of birth and death\nrate leads to the suppression of speed of sound wave and density fluctuations\nin the system."
    },
    {
        "anchor": "Chemically Active Nanodroplets in a Multi-Component Fluid: We introduce a model of chemically active particles of a multi-component\nfluid that can change their interactions with other particles depending on\ntheir state. Since such switching of interactions can only be maintained by the\ninput of chemical energy, the system is inherently non-equilibrium. Focusing on\na scenario where the equilibrium interactions would lead to condensation into a\nliquid droplet, and despite the relative simplicity of the interaction rules,\nthese systems display a wealth of interesting and novel behaviors such as\noscillations of droplet size and molecular sorting, and raise the possibility\nof spatio-temporal control of chemical reactions on the nanoscale",
        "positive": "Self-assembly of polymers or copolymers and ferrofluids leading to\n  either 1-d, 2-d or 3-d aggregates decorated with magnetic nanoparticles: A novel type of hybrid colloids is presented, based on the association of\nseveral polymeric systems and ferrofluids. On the one hand, we use inorganic\nnanoparticles made of magnetic iron oxide prepared at the LI2C, which response\nto a magnetic field of low intensity. On the other hand the organic part is\nmade either of long linear polyacrylamide chains or of mesoscopic structures\n(vesicles and micelles) self-assembled from amphiphile\npolybutadiene-b-poly(glutamic acid) di-block copolymers, which conformation is\npH-sensitive."
    },
    {
        "anchor": "Grain-scale Modeling and Splash Parametrization for Aeolian Sand\n  Transport: The collision of a spherical grain with a granular bed is commonly\nparametrized by the splash function, which provides the velocity of the\nrebounding grain and the velocity distribution and number of ejected grains.\nStarting from elementary geometric considerations and physical principles, like\nmomentum conservation and energy dissipation in inelastic pair collisions, we\nderive a rebound parametrization for the collision of a spherical grain with a\ngranular bed. Combined with a recently proposed energy-splitting model [Ho\n${\\it et\\ al.}$, Phys. Rev. E 85, 052301 (2012)] that predicts how the impact\nenergy is distributed among the bed grains, this yields a coarse-grained but\ncomplete characterization of the splash as a function of the impact velocity\nand the impactor-bed grain-size ratio. The predicted mean values of the rebound\nangle, total and vertical restitution, ejection speed, and number of ejected\ngrains are in excellent agreement with experimental literature data and with\nour own discrete-element computer simulations. We extract a set of analytical\nasymptotic relations for shallow impact geometries, which can readily be used\nin coarse-grained analytical modeling or computer simulations of geophysical\nparticle-laden flows.",
        "positive": "Boojums and the Shapes of Domains in Monolayer Films: Domains in Langmuir monolayers support a texture that is the two-dimensional\nversion of the feature known as a boojum. Such a texture has a quantifiable\neffect on the shape of the domain with which it is associated. The most\nnoticeable consequence is a cusp-like feature on the domain boundary. We report\nthe results of an experimental and theoretical investigation of the shape of a\ndomain in a Langmuir monolayer. A further aspect of the investigation is the\nstudy of the shape of a ``bubble'' of gas-like phase in such a monolayer. This\nstructure supports a texture having the form of an inverse boojum. The\ndistortion of a bubble resulting from this texture is also studied. The\ncorrespondence between theory and experiment, while not perfect, indicates that\na qualitative understanding of the relationship between textures and domain\nshapes has been achieved."
    },
    {
        "anchor": "Two-dimensional Cahn-Hilliard simulations for coarsening kinetics of\n  spinodal decomposition in binary mixtures: The evolution of the microstructure due to spinodal decomposition in phase\nseparated mixtures has a strong impact on the final material properties. In the\nlate stage of coarsening, the system is characterized by the growth of a single\ncharacteristic length scale $L\\sim C t^{\\alpha}$. To understand the\nstructure-property relationship, the knowledge of the coarsening exponent\n$\\alpha$ and the coarsening rate constant $C$ is mandatory. Since the existing\nliterature is not entirely consistent, we perform phase field simulations based\non the Cahn-Hilliard equation. We restrict ourselves to binary mixtures using a\nsymmetric Flory-Huggins free energy and a constant mobility term and show that\nthe coarsening for off-critical mixtures is slower than the expected\n$t^{1/3}$-growth. Instead, we find $\\alpha$ to be dependent on the mixture\ncomposition and thus from the morphology. Finally, we propose a model to\ndescribe the complete coarsening kinetics including the rate constant $C$.",
        "positive": "Finite-disorder critical point in the yielding transition of\n  elasto-plastic models: Upon loading, amorphous solids can exhibit brittle yielding, with the abrupt\nformation of macroscopic shear bands leading to fracture, or ductile yielding,\nwith a multitude of plastic events leading to homogeneous flow. It has been\nrecently proposed, and subsequently questioned, that the two regimes are\nseparated by a sharp critical point, as a function of some control parameter\ncharacterizing the intrinsic disorder strength and the degree of stability of\nthe solid. In order to resolve this issue, we have performed extensive\nnumerical simulations of athermally driven elasto-plastic models with\nlong-range and anisotropic realistic interaction kernels in two and three\ndimensions. Our results provide clear evidence for a finite-disorder critical\npoint separating brittle and ductile yielding, and we provide an estimate of\nthe critical exponents in 2D and 3D."
    },
    {
        "anchor": "Hydrodynamics within the Electric Double Layer on slipping surfaces: We show, using extensive Molecular Dynamics simulations, that the dynamics of\nthe electric double layer (EDL) is very much dependent on the wettability of\nthe charged surface on which the EDL develops. For a wetting surface, the\ndynamics, characterized by the so-called Zeta potential, is mainly controlled\nby the electric properties of the surface, and our work provides a clear\ninterpretation for the traditionally introduced immobile Stern layer. In\ncontrast, the immobile layer disappears for non-wetting surfaces and the Zeta\npotential deduced from electrokinetic effects is considerably amplified by the\nexistence of a slippage at the solid substrate.",
        "positive": "Weakly adhesive suspension shows rate-dependence in oscillatory but not\n  steady shear flows: We report rheological measurements of a noncolloidal particle suspension in a\nNewtonian solvent at 40% solid volume fraction. An anomalous,\nfrequency-dependent complex viscosity is found under oscillatory shear (OS)\nflow, whereas a constant dynamic viscosity is found under the same shear rates\nin steady shear (SS) flow. We show that this contradiction arises from the\nunderlying microstructural difference between OS and SS, mediated by weak\ninterparticle forces. Discrete element simulations of proxy particle\nsuspensions confirm this hypothesis and reveal an adhesion-induced, shear\nthinning mechanism with a -1/5 slope, only in OS, in agreement with\nexperiments."
    },
    {
        "anchor": "Elastic wave velocities in finitely pre-stretched soft fibers: Elastic wave velocity in a soft fiber that varies depending on material\nconstitution and axial stress level is an essential measure of mechanical\nsignals in many technical applications. In this work, based on the\nsmall-on-large theory, we establish a model of linear elastic wave propagation\nin a finitely pre-stretched soft fiber. The formulas of longitudinal (Primary,\nP-) and transverse (Secondary, S-) wave velocities are provided and validated\nby numerical simulations as well as by experimental data on spider silk. The\ninfluences of material constitution, compressibility, and pre-stress on the\nwave propagation are investigated. We found that with increasing pre-stress,\nthe variation of P-wave velocity highly relies on the concavity of the\nstress-strain curve. In contrast, an increase of S-wave velocity exhibits\nregardless of any constitutive model. For both P- and S-waves, the variation of\nthe velocities is more significant in a compressible fiber than that in a\nnearly-incompressible one. Moreover, for minuscule pre-stress, we propose a\nmodified formula for S-wave velocity based on the Rayleigh beam theory, which\nreveals the competition mechanism between \"string vibration\" and \"beam\nvibration.\" This may provide a reliable theoretical basis for precise\nmechanical characterization of soft fibers and open a route for lightweight,\ntunable wave manipulation devices.",
        "positive": "Probability Distributions and Particle Number Fluctuations of Trapped\n  Bose-Einstein Condensates in Different Dimensions: The analytical probability distribution of finite systems obeying\nBose-Einstein statistics in one, two, and three dimensions are investigated by\nusing a canonical ensemble approach. Starting from the canonical partition\nfunction of the system, a unified approach is provided to study the probability\ndistribution of a condensate for various confinements and in different\ndimensions. Based on the probability distribution function, it is\nstraightforward to obtain the mean ground state occupation number and particle\nnumber fluctuations of the condensate. It is found that the particle number\nfluctuations in a trapped Bose gas are strongly dependent on the type of\nconfining potential and on the dimensionality of the system."
    },
    {
        "anchor": "On the size and shape of excluded volume polymers confined between\n  parallel plates: A number of recent experiments have provided detailed observations of the\nconfigurations of long DNA strands under nano-to-micrometer sized confinement.\nWe therefore revisit the problem of an excluded volume polymer chain confined\nbetween two parallel plates with varying plate separation. We show that the\nnon-monotonic behavior of the overall size of the chain as a function of\nplate-separation, seen in computer simulations and reproduced by earlier\ntheories, can already be predicted on the basis of scaling arguments. However,\nthe behavior of the size in a plane parallel to the plates, a quantity observed\nin recent experiments, is predicted to be monotonic, in contrast to the\nexperimental findings. We analyze this problem in depth with a mean-field\napproach that maps the confined polymer onto an anisotropic Gaussian chain,\nwhich allows the size of the polymer to be determined separately in the\nconfined and unconfined directions. The theory allows the analytical\nconstruction of a smooth cross-over between the small plate-separation de\nGennes regime and the large plate-separation Flory regime. The results show\ngood agreement with Langevin dynamics simulations, and confirm the scaling\npredictions.",
        "positive": "Glassy anomalies in the low-temperature thermal properties of a\n  minimally disordered crystalline solid: The low-temperature thermal and transport properties of an unusual kind of\ncrystal exhibiting minimal molecular positional and tilting disorder have been\nmeasured. The material, namely, low-dimensional, highly anisotropic\npentachloronitrobenzene (PCNB) has a layered structure of rhombohedral parallel\nplanes in which the molecules execute large-amplitude in-plane as well as\nconcurrent out-of-plane librational motions. Our study reveals that\nlow-temperature glassy anomalies can be found in a system with minimal disorder\ndue to the freezing of (mostly in-plane) reorientational jumps of molecules\nbetween equivalent crystallographic positions with partial site occupation. Our\nfindings will pave the way to a deeper understanding of the origin of\nabove-mentioned universal glassy properties at low temperature."
    },
    {
        "anchor": "Fermi excitations in a trapped atomic Fermi gas with a molecular Bose\n  condensate: We discuss the effect of a molecular Bose condensate on the energy of Fermi\nexcitations in a trapped two-component atomic Fermi gas. The single-particle\nGreen's functions can be approximated by the well-known BCS form, in both the\nBCS (Cooper pairs) and BEC (Feshbach resonance molecules) domains. The\ncomposite Bose order parameter ${\\tilde\n  \\Delta}$ describing bound states of two atoms and the Fermi chemical\npotential $\\mu$ are calculated self-consistently. In the BEC regime\ncharacterized by $\\mu<0$, the Fermi quasiparticle energy gap is given by\n$\\sqrt{\\mu^2+{\\tilde \\Delta}^2}$, instead of $|{\\tilde \\Delta}|$ in the BCS\nregion, where $\\mu>0$. This shows up in the characteristic energy of atoms from\ndissociated molecules.",
        "positive": "Entropy and relaxation time: This paper discusses the possible relation between entropy and the relaxation\ntime of liquids, in particular glass-forming systems, providing supplementing\ncomments to the paper entitled \"A brief critique of the Adam-Gibbs entropy\nmodel\" by Hecksher et al. [J. Non-Cryst. Solids 325, 624-627 (2009)]. Besides\nthe Adam-Gibbs model, we also briefly discuss Rosenfeld's excess entropy\nscaling and the 1964 experimental observation by Chang and Bestul of a\nuniversal excess entropy at the glass transition."
    },
    {
        "anchor": "Atom interferometry with Bose-Einstein condensates in a double-well\n  potential: A trapped-atom interferometer was demonstrated using gaseous Bose-Einstein\ncondensates coherently split by deforming an optical single-well potential into\na double-well potential. The relative phase between the two condensates was\ndetermined from the spatial phase of the matter wave interference pattern\nformed upon releasing the condensates from the separated potential wells.\nCoherent phase evolution was observed for condensates held separated by 13\n$\\mu$m for up to 5 ms and was controlled by applying ac Stark shift potentials\nto either of the two separated condensates.",
        "positive": "Infrared dichroism of gold nanorods controlled using a magnetically\n  addressable mesophase: Gold nanorods have unique optical properties, which make them promising\ncandidates for building nano-structured materials using a \"bottom-up\" strategy.\nWe formulate stable bulk materials with anisotropic optical properties by\ninserting gold and iron oxide nanorods within a lamellar mesophase.\nQuantitative measurements of the order parameter by modelling the absorbance\nspectra show that the medium is macroscopically aligned in a direction defined\nby an external magnetic field. Under field, the system exhibits significant\nabsorption dichroism in the infrared range, at the position of the longitudinal\nplasmon peak of the gold nanorods (about 1200 nm), indicating strong\nconfinement of these particles within the water layers of the lamellar phase.\nThis approach can yield soft and addressable optical elements."
    },
    {
        "anchor": "Local Simulation Algorithms for Coulomb Gases with Dynamical Dielectric\n  Effects: We discuss the application of the local lattice technique of Maggs and\nRossetto to problems that involve the motion of objects with different\ndielectric constants than the background. In these systems the simulation\nmethod produces a spurious interaction force which causes the particles to move\nin an unphysical manner. We show that this term can be removed using a variant\nof a method known from high-energy physics simulations, the multiboson method,\nand demonstrate the effectiveness of this corrective method on a system of\nneutral particles. We then apply our method to a one-component plasma to show\nthe effect of the spurious interaction term on a charged system.",
        "positive": "Heated granular fluids: the random restitution coefficient approach: We introduce the model of inelastic hard spheres with random restitution\ncoefficient $\\alpha$, in order to account for the fact that, in a vertically\nshaken granular system interacting elastically with the vibrating boundary, the\nenergy injected vertically is transferred to the horizontal degrees of freedom\nthrough collisions only, which leads to heating through collisions, i.e. to\ninelastic horizontal collisions with an effective restitution coefficient that\ncan be larger than 1. This allows the system to reach a non-equilibrium steady\nstate, where we focus in particular on the single particle velocity\ndistribution $f(v)$ in the horizontal plane, and on its deviation from a\nMaxwellian. Molecular Dynamics simulations and Direct Simulation Monte Carlo\n(DSMC) show that, depending on the distribution of $\\alpha$, different shapes\nof $f(v)$ can be obtained, with very different high energy tails. Moreover, the\nfourth cumulant of the velocity distribution quantifying the deviations from\nGaussian statistics is obtained analytically from the Boltzmann equation and\nsuccessfully tested against the simulations."
    },
    {
        "anchor": "The yielding of concentrated cohesive suspensions can be deformation\n  rate dependent: The yielding of concentrated cohesive suspensions can be deformation-rate\ndependent. One consquence of this is that a single suspension can present in\none several different ways, depending upon how it is tested, or more generally,\nhow it is caused to flow. We have seen variously Herschel-Bulkley flow, highly\nnon-monotonic flow curves and highly erratic or chaotic yield, all in one\nsuspension. In controlled-rate testing one sees a systematic effect of\ndeformation rate. In controlled stress testing, matters are more subtle.\nWhereas step-stress creep testing will elicit reproducible behaviour, any\nattempt to determine a flow curve by, e.g. stepping up or sweeping stress at an\ninappropriate rate can lead to highly irreproducible behaviour.",
        "positive": "A surface force apparatus for nanorheology under large shear strain: We describe a surface force apparatus designed to probe the rheology of a\nnanoconfined medium under large shear amplitudes (up to 500 $\\mu$m). The\ninstrument can be operated in closed-loop, controlling either the applied\nnormal load or the thickness of the medium during shear experiments. Feedback\ncontrol allows to greatly extend the range of confinement/shear strain\nattainable with the surface force apparatus. The performances of the instrument\nare illustrated using hexadecane as the confined medium."
    },
    {
        "anchor": "Polar liquid crystals in two spatial dimensions: the bridge from\n  microscopic to macroscopic modeling: Two-dimensional polar liquid crystals have been discovered recently in\nmonolayers of anisotropic molecules. Here, we provide a systematic theoretical\ndescription of liquid-crystalline phases for polar particles in two spatial\ndimensions. Starting from microscopic density functional theory, we derive a\nphase-field-crystal expression for the free-energy density which involves three\nlocal order-parameter fields, namely the translational density, the\npolarization, and the nematic order parameter. Various coupling terms between\nthe order-parameter fields are obtained which are in line with macroscopic\nconsiderations. Since the coupling constants are brought into connection with\nthe molecular correlations, we establish a bridge from microscopic to\nmacroscopic modeling. Our theory provides a starting point for further\nnumerical calculations of the stability of polar liquid-crystalline phases and\nis also relevant for modeling of microswimmers which are intrinsically polar.",
        "positive": "Cooperation in a fluid swarm of fuel-free micro-swimmers: Cooperation is vital for the survival of a swarm$^1$. Large scale cooperation\nallows murmuring starlings to outmaneuver preying falcons$^2$, shoaling\nsardines to outsmart sea lions$^3$, and homo sapiens to outlive their\nPleistocene peers$^4$. On the micron-scale, bacterial colonies show excellent\nresilience thanks to the individuals' ability to cooperate even when densely\npacked, mitigating their internal flow pattern to mix nutrients, fence the\nimmune system, and resist antibiotics$^{5-14}$. Production of an artificial\nswarm on the micro-scale faces a serious challenge $\\frac{\\;\\;}{\\;\\;}$ while an\nindividual bacterium has an evolutionary-forged internal machinery to produce\npropulsion, until now, artificial micro-swimmers relied on the precise chemical\ncomposition of their environment to directly fuel their drive$^{14-23}$. When\ncrowded, artificial micro-swimmers compete locally for a finite fuel supply,\nquenching each other's activity at their greatest propensity for cooperation.\nHere we introduce an artificial micro-swimmer that consumes no chemical fuel\nand is driven solely by light. We couple a light absorbing particle to a fluid\ndroplet, forming a colloidal chimera that transforms light energy into\npropulsive thermo-capillary action. The swimmers' internal drive allows them to\noperate and remain active for a long duration (days) and their effective\nrepulsive interaction allows for a high density fluid phase. We find that above\na critical concentration, swimmers form a long lived crowded state that\ndisplays internal dynamics. When passive particles are introduced, the dense\nswimmer phase can re-arrange and spontaneously corral the passive particles. We\nderive a geometrical, depletion-like condition for corralling by identifying\nthe role the passive particles play in controlling the effective concentration\nof the micro-swimmers."
    },
    {
        "anchor": "Percolation in a Model Transient Network: Rheology and Dynamic Light\n  Scattering: Step strain experiments and dynamic light scattering measurements are\nperfomed to characterize the dynamic behavior of an o/w droplet microemulsion\ninto which is incorporated a telechelic polymer. At sufficient droplet and\npolymer concentrations, above the percolation threshold, the system is\nviscoelastic and its dynamic structure factor shows up two steps for the\nrelaxation of concentration fluctuations: the fast one is dominated by the\ndiffusion but the slower one is almost independent of the wave vector. The\nterminal time of the stress relaxation tR and the slow time of the dynamic\nstructure factor tS are both presumably controlled by the residence time of a\nsticker in a droplet: consistently, tR and tS are of the same order, they both\nvanishes at the percolation threshold according to power laws but with\ndifferent exponents. We discuss these features in terms of deviations at the\ntransition, from the usual mean field description of the dynamics of transient\nnetworks.",
        "positive": "Electroferrofluids with non-equilibrium voltage-controlled magnetism,\n  interfaces, and patterns: Materials with continuous dissipation can exhibit responses and\nfunctionalities that are not possible in thermodynamic equilibrium. While this\nconcept is well-known, a major challenge has been the implementation: how to\nrationally design materials with functional non-equilibrium states and quantify\nthe dissipation? Here we address these questions for the widely used colloidal\nnanoparticles that convey several functionalities. We propose that useful\nnon-equilibrium states can be realised by creating and maintaining steady-state\nnanoparticle concentration gradients by continuous injection and dissipation of\nenergy. We experimentally demonstrate this with superparamagnetic iron oxide\nnanoparticles that in thermodynamic equilibrium form a homogeneous functional\nfluid with a strong magnetic response (a ferrofluid). To create non-equilibrium\nfunctionalities, we charge the nanoparticles with anionic charge control agents\nto create electroferrofluids where nanoparticles act as charge carriers that\ncan be driven with electric fields and current to non-homogeneous dissipative\nsteady-states. The dissipative steady-states exhibit voltage-controlled\nmagnetic properties and emergent diffuse interfaces. The diffuse interfaces\nrespond strongly to external magnetic fields, leading to dissipative patterns\nthat are not possible in the equilibrium state. We identify the closest\nnon-dissipative analogues of these dissipative patterns, discuss the\ndifferences, and highlight how pattern formation in electroferrofluids is\nlinked to dissipation that can be directly quantified. Beyond electrically\ncontrolled ferrofluids and patterns, we foresee that the concept can be\ngeneralized to other functional nanoparticles to create various scientifically\nand technologically relevant non-equilibrium states with optical, electrical,\ncatalytic, and mechanical responses that are not possible in thermodynamic\nequilibrium."
    },
    {
        "anchor": "Physical ageing of spreading droplets in a viscous ambient phase: Nanoscale topographic features of solid surfaces can induce complex\nmetastable behavior in colloidal and multiphase systems. Recent studies on\nsingle microparticle adsorption at liquid interfaces have reported a crossover\nfrom fast capillary driven dynamics to extremely slow kinetic regimes that can\nrequire up to several hours or days to attain thermodynamic equilibrium. The\nobserved kinetic regime resembling physical ageing in glassy materials has been\nattributed to unobserved surface features with dimensions on the order of a few\nnanometers. In this work, we study the spontaneous spreading of water droplets\nimmersed in oil and report an unexpectedly slow kinetic regime not described by\nprevious spreading models. We can quantitatively describe the observed regime\ncrossover and spreading rate in the late kinetic regime with an analytical\nmodel considering the presence of periodic metastable states induced by\nnanoscale topographic features (characteristic area ~4 nm^2, height ~1 nm)\nobserved via atomic force microscopy. The analytical model proposed in this\nwork reveals that certain combinations of droplet volume and nanoscale\ntopographic parameters can significantly hinder or promote wetting processes\nsuch as spreading, wicking, and imbibition.",
        "positive": "Active responsive colloids driven by intrinsic dichotomous noise: We study the influence of intrinsic noise on the structure and dynamics of\nresponsive colloids (RCs) which actively change their size and mutual\ninteractions. The colloidal size is explicitly resolved in our RC model as an\ninternal degree of freedom (DOF) in addition to the particle translation. A\nHertzian pair potential between the RCs leads to repulsion and shrinking of the\nparticles, resulting in an explicit responsiveness of the system to\nself-crowding. To render the colloids active, their size is internally driven\nby a dichotomous noise, randomly switching ('breathing') between growing and\nshrinking states with a predefined rate, as motivated by recent experiments on\nsynthetic active colloids. The polydispersity of this dichotomous active\nresponsive colloid (D-ARC) model can be tuned by the parameters of the noise.\nUtilizing stochastic computer simulations, we study crowding effects on the\nspatial distributions, relaxation times, and self-diffusion of dense\nsuspensions of the D-ARCs. We find a substantial influence of the 'built-in'\nintrinsic noise on the system's behavior, in particular, transitions from\nunimodal to bimodal size distributions for an increasing colloid density as\nwell as intrinsic noise-modified diffusive translational dynamics. We conclude\nthat controlling the noise of internal DOFs of a macromolecule or cell is a\npowerful tool for active colloidal materials to enable autonomous changes in\nthe system's collective structure and dynamics towards the adaption of\nmacroscopic properties to external perturbations."
    },
    {
        "anchor": "Memory from coupled instabilities in unfolded crumpled sheets: Crumpling an ordinary thin sheet transforms it into a structure with unusual\nmechanical behaviors, such as enhanced rigidity, emission of crackling noise,\nslow relaxations, and memory retention. A central challenge in explaining these\nbehaviours lies in understanding the contribution of the complex geometry of\nthe sheet. Here, we combine cyclic driving protocols and 3D imaging to\ncorrelate the global mechanical response and the underlying geometric\ntransformations in unfolded crumpled sheets. We find that their response to\ncyclic strain is intermittent, hysteretic, and encodes a memory of the largest\napplied compression. Using 3D imaging, we show that these behaviours emerge due\nto an interplay between localized and interacting geometric instabilities in\nthe sheet. A simple model confirms that these minimal ingredients are\nsufficient to explain the observed behaviors. Finally, we show that after\ntraining multiple memories can be encoded, a phenomenon known as return point\nmemory. Our study lays the foundation for understanding the complex mechanics\nof crumpled sheets and presents an experimental and theoretical framework for\nthe study of memory formation in systems of interacting instabilities.",
        "positive": "Phase behavior and rheology of sticky rod-like particles: We construct colloidal ``sticky'' rods from the semi-flexible filamentous fd\nvirus and temperature-sensitive polymers poly(N-isopropylacrylamide) (PNIPAM).\nThe phase diagram of fd-PNIPAM system becomes independent of ionic strength at\nhigh salt concentration and low temperature, i.e. the rods are sterically\nstabilized by the polymer. However, the network of sticky rods undergoes a\nsol-gel transition as the temperature is raised. The viscoelastic moduli of fd\nand fd-PNIPAM suspensions are compared as a function of temperature, and the\neffect of ionic strength on the gelling behavior of fd-PNIPAM solution is\nmeasured. For all fluidlike and solidlike samples, the frequency-dependant\nlinear viscoelastic moduli can be scaled onto universal master curves."
    },
    {
        "anchor": "Far-from-equilibrium Ostwald ripening in electrostatically driven\n  granular powders: We report the first experimental study of cluster size distributions in\nelectrostatically driven granular submonolayers. The cluster size distribution\nin this far-from-equilibrium process exhibits dynamic scaling behavior\ncharacteristic of the (nearly equilibrium) Ostwald ripening, controlled by the\nattachment and detachment of the \"gas\" particles. The scaled size distribution,\nhowever, is different from the classical Wagner distribution obtained in the\nlimit of a vanishingly small area fraction of the clusters. A much better\nagreement is found with the theory of Conti et al. [Phys. Rev. E 65, 046117\n(2002)] which accounts for the cluster merger.",
        "positive": "Layered tungsten oxide-based organic/inorganic hybrid materials I:\n  Infrared and Raman study: Tungsten oxide-organic layered hybrid materials have been studied by infrared\nand Raman spectroscopy, and demonstrate a difference in bonding nature as the\nlength of the interlayer organic `spacer' molecule is increased.\nEthylenediamine-tungsten oxide clearly displays a lack of terminal -NH3+\nammonium groups which appear in hybrids with longer alkane molecules, thus\nindicating that the longer chains are bound by electrostatic interactions as\nwell as or in place of the hydrogen bonding that must be present in the shorter\nchain ethylenediamine hybrids. The presence of organic molecules between the\ntungsten oxide layers, compared with the layered tungstic acid H2WO4, shows a\ndecrease in the apical W=O bond strength, as might be expected from the\naforementioned electrostatic interaction."
    },
    {
        "anchor": "Influence of Bubbles on the Energy Conversion Efficiency of\n  Electrochemical Reactors: Bubbles are known to influence energy and mass transfer in gas evolving\nelectrodes. However, we lack a detailed understanding on the intricate\ndependencies between bubble evolution processes and electrochemical phenomena.\nThis review discusses our current knowledge on the effects of bubbles on\nelectrochemical systems with the aim to identify opportunities and motivate\nfuture research in this area. We first provide a base background on the physics\nof bubble evolution as it relates to electrochemical processes. Then we outline\nhow bubbles affect energy efficiency of electrode processes, detailing the\nbubble-induced impacts on activation, ohmic and concentration overpotentials.\nLastly, we describe different strategies to mitigate losses and how to exploit\nbubbles to enhance electrochemical reactions.",
        "positive": "Curvature screening in draped mechanical metamaterial sheet: We develop a framework to understand the mechanics of metamaterial sheets on\ncurved surfaces. Here we have constructed a continuum elastic theory of\nmechanical metamaterials by introducing an auxiliary, scalar gauge-like field\nthat absorbs the strain along the soft mode and projects out the stiff ones. We\npropose a general form of the elastic energy of a mechanism based metamaterial\nsheet and specialize to the cases of dilational metamaterials and shear\nmetamaterials conforming to positively and negatively curved substrates in the\nF\\\"{o}ppl-Von K\\'{a}rm\\'{a}n limit of small strains. We perform numerical\nsimulations of these systems and obtain good agreement with our analytical\npredictions. This work provides a framework that can be easily extended to\nexplore non-linear soft modes in metamaterial elasticity in future."
    },
    {
        "anchor": "Study of dynamical heterogeneities in aging colloidal nanoclay\n  suspensions: An aqueous suspension of the synthetic clay Laponite undergoes a transition\nfrom a liquid-like ergodic state to a glass-like nonergodic arrested state. In\nan observation that closely resembles the dynamical slowdown observed in\nsupercooled liquids, the phenomenon of kinetic arrest in Laponite suspensions\nis accompanied by a growth in the $\\alpha$-relaxation time with increasing\nsample aging time, $t_{w}$. The ubiquitous dynamic slowdown and fragile\nbehavior observed in glass forming liquids approaching the glass transition is\ntypically ascribed to the growth in the size of distinct dynamical\nheterogeneities. In this article, we present the characterization of the\ndynamical heterogeneities in aging colloidal Laponite clay systems by invoking\nthe three-point dynamic susceptibility formalism. The average time-dependent\ntwo-point intensity autocorrelation and its sensitivity to the control\nparameter $t_{w}$ are probed in dynamic light scattering experiments.\nDistributions of relaxation time scales deduced from Kohlrausch-Williams-Watts\nequation widen with increasing $t_{w}$ signifying the heterogeneous dynamic\nslowdown. A suitable formalism to calculate three-point correlation function is\nemployed for aging colloidal suspension where the main control parameter is\n$t_{w}$. The calculated three-point dynamic susceptibility exhibits a peak,\nwith the peak height increasing with evolving $t_{w}$. The number of\ndynamically correlated particles is seen to initially increase with increasing\n$t_{w}$ at a fast rate, before eventually slowing down close to the non-ergodic\ntransition point.This observation is in agreement with reports on supercooled\nliquids. Our study confirms the growth of dynamical heterogeneities in\nsuspensions of Laponite, thereby shedding new light on the fragile supercooled\nliquid-like dynamics of aging suspensions of these anisotropic, charged,\ncolloidal clay nanoparticles.",
        "positive": "Free energy calculations along entropic pathways: II. Droplet nucleation\n  in binary mixtures: Using molecular simulation, we study the nucleation of liquid droplets from\nbinary mixtures and determine the free energy of nucleation along entropic\npathways. To this aim, we develop the $\\mu_1 \\mu_2 VT-S$ method, based on the\ngrand-canonical ensemble modeling the binary mixture, and use the entropy of\nthe system $S$ as the reaction coordinate to drive the formation of the liquid\ndroplet. This approach builds on the advantages of the grand-canonical\nensemble, which allows for the direct calculation of the entropy of the system\nand lets the composition of the system free to vary throughout the nucleation\nprocess. Starting from a metastable supersaturated vapor, we are able to form a\nliquid droplet by gradually decreasing the value of $S$, through a series of\numbrella sampling simulations, until a liquid droplet of a critical size has\nformed. The $\\mu_1 \\mu_2 VT-S$ method also allows us to calculate the free\nenergy barrier associated with the nucleation process, to shed light on the\nrelation between supersaturation and free energy of nucleation, and to analyze\nthe interplay between the size of the droplet and its composition during the\nnucleation process."
    },
    {
        "anchor": "Quasi-static microdroplet production in a capillary trap: We have developed a method to produce aqueous microdroplets in an oil phase,\nbased on the periodic extraction of a pending droplet across the oil/air\ninterface. This interface forms a capillary trap inside which a droplet can be\ncaptured and detached. This process is found to be capillary- based and\nquasi-static. The droplet size and emission rate are independently governed by\nthe injected volume per cycle and the extraction frequency. We find that the\nminimum droplet diameter is close to the injection glass capillary diameter and\nthat variations in surface tension moderately perturb the droplet size. A\ntheoretical model based on surface energy minimization in the oil/water/air\nphases was derived and captures the experimental results. This method enables\nrobust, versatile and tunable production of microdroplets at low production\nrates.",
        "positive": "Nano-Pump base on Exothermic Surface Reactions: We present simulations indicating that it should be possible to construct a\nswitchable nano-scale fluid pump, driven by exothermic surface reactions. Such\na pump could, for instance, be controlled electro-chemically. In our\nsimulations we explore a simple illustration of such a pump. We argue that the\nsimplicity of the pump design could make it attractive for micro/nano-fluidics\napplications."
    },
    {
        "anchor": "Broad Band Photon Harvesting Biomolecules for Photovoltaics: We discuss the key principles of artificial photosynthesis for photovoltaic\nenergy conversion. We demonstrate these principles by examining the operation\nof the so-called \"dye sensitized solar cell\" (DSSC) - a photoelectrochemical\ndevice which simulates the charge separation process across a nano-structured\nmembrane that is characteristic of natural systems. These type of devices have\ngreat potential to challenge silicon semiconductor technology in the low cost,\nmedium efficiency segment of the PV market. Ruthenium charge transfer complexes\nare currently used as the photon harvesting components in DSSCs. They produce a\nrelatively broad band UV and visible response, but have long term stability\nproblems and are expensive to manufacture. We suggest that a class of\nbiological macromolecules called the melanins may be suitable replacements for\nthe ruthenium complexes. They have strong, broad band absorption, are\nchemically and photochemically very stable, can be cheaply and easily\nsynthesized, and are also bio-available and bio-compatible. We demonstrate a\nmelanin-based regenerative solar cell, and discuss the key properties that are\nnecessary for an effective broad band photon harvesting system.",
        "positive": "Laning and Clustering Transitions in Driven Binary Active Matter Systems: It is well known that a binary system of non-active disks that experience\ndriving in opposite directions exhibits jammed, phase separated, disordered,\nand laning states. In active matter systems, such as a crowd of pedestrians,\ndriving in opposite directions is common and relevant, especially in conditions\nwhich are characterized by high pedestrian density and emergency. In such\ncases, the transition from laning to disordered states may be associated with\nthe onset of a panic state. We simulate a laning system containing active disks\nthat obey run-and-tumble dynamics, and we measure the drift mobility and\nstructure as a function of run length, disk density, and drift force. The\nactivity of each disk can be quantified based on the correlation timescale of\nthe velocity vector. We find that in some cases, increasing the activity can\nincrease the system mobility by breaking up jammed configurations; however, an\nactivity level that is too high can reduce the mobility by increasing the\nprobability of disk-disk collisions. In the laning state, the increase of\nactivity induces a sharp transition to a disordered strongly fluctuating state\nwith reduced mobility. We identify a novel drive-induced clustered laning state\nthat remains stable even at densities below the activity-induced clustering\ntransition of the undriven system."
    },
    {
        "anchor": "Precise algorithms to compute surface correlation functions of two-phase\n  heterogeneous media and their applications: The quantitative characterization of the microstructure of random\nheterogeneous media in $d$-dimensional Euclidean space $\\mathbb{R}^d$ via a\nvariety of $n$-point correlation functions is of great importance, since the\nrespective infinite set determines the effective physical properties of the\nmedia. In particular, surface-surface $F_{ss}$ and surface-void $F_{sv}$\ncorrelation functions (obtainable from radiation scattering experiments)\ncontain crucial interfacial information that enables one to estimate transport\nproperties of the media (e.g., the mean survival time and fluid permeability)\nand complements the information content of the conventional two-point\ncorrelation function. However, the current technical difficulty involved in\nsampling surface correlation functions has been a stumbling block in their\nwidespread use. We first present a concise derivation of the small-$r$\nbehaviors of these functions, which are linked to the \\textit{mean curvature}\nof the system. Then we demonstrate that one can reduce the computational\ncomplexity of the problem by extracting the necessary interfacial information\nfrom a cut of the system with an infinitely long line. Accordingly, we devise\nalgorithms based on this idea and test them for two-phase media in continuous\nand discrete spaces. Specifically for the exact benchmark model of overlapping\nspheres, we find excellent agreement between numerical and exact results. We\ncompute surface correlation functions and corresponding local surface-area\nvariances for a variety of other model microstructures, including hard spheres\nin equilibrium, decorated \"stealthy\" patterns, as well as snapshots of evolving\npattern formation processes (e.g., spinodal decomposition). It is demonstrated\nthat the precise determination of surface correlation functions provides a\npowerful means to characterize a wide class of complex multiphase\nmicrostructures.",
        "positive": "Fluctuation spectra of free and supported membrane pairs: Fluctuation spectra of fluid compound membrane systems are calculated. The\nsystems addressed contain two (or more) almost parallel membranes that are\nconnected by harmonic tethers or by a continuous, harmonic confining potential.\nAdditionally, such a compound system can be attached to a supporting substrate.\nWe compare quasi-analytical results for tethers with analytical results for\ncorresponding continuous models and investigate under what circumstances the\ndiscrete nature of the tethers actually influences the fluctuations. A\ntethered, supported membrane pair with similar bending rigidities and stiff\ntethers can possess a nonmonotonic fluctuation spectrum with a maximum. A\nnonmonotonic spectrum with a maximum and a minimum can occur for an either free\nor supported membrane pair of rather different bending rigidities and for stiff\ntethers. Typical membrane displacements are calculated for supported membrane\npairs with discrete or continuous interacting potentials. Thereby an estimate\nof how close the constituent two membranes and the substrate typically approach\neach other is given. For a supported membrane pair with discrete or continuous\ninteractions, the typical displacements of each membrane are altered with\nrespect to a single supported membrane, where those of the membrane near the\nsubstrate are diminished and those of the membrane further away are enhanced."
    },
    {
        "anchor": "Fast-freezing kinetics inside a droplet impacting on a cold surface: Freezing or solidification of impacting droplets is omnipresent in nature and\ntechnology, be it a rain droplet falling on a supercooled surface, be it in\ninkjet printing where often molten wax is used, be it in added manufacturing or\nin metal production processes or in extreme ultraviolet lithography (EUV) for\nthe chip production where molten tin is used to generate the EUV radiation. For\nmany of these industrial applications, a detailed understanding of the\nsolidification process is essential. Here, by adopting a totally new optical\ntechnique in the context of freezing, namely TIR (Total-Internal-Reflection),\nwe elucidate the freezing kinetics during the solidification of a droplet while\nit impacts on an undercooled surface. We show for the first time that at\nsufficiently high undercooling a peculiar freezing morphology exists that\ninvolves sequential advection of frozen fronts from the centre of the droplet\nto its boundaries. This phenomenon is examined by combining elements of\nclassical nucleation theory to the large scale hydrodynamics on the droplet\nscale, bringing together two subfields which traditionally have been quite\nseparated. Furthermore, we report a peculiar self-peeling phenomenon of a\nfrozen splat that is driven by the existence of a transient crystalline state\nduring solidification.",
        "positive": "Bending and Gaussian rigidities of confined soft spheres from\n  second-order virial series: We use virial series to study the equilibrium properties of confined\nsoft-spheres fluids interacting through the inverse-power potentials. The\nconfinement is induced by hard walls with planar, spherical and cylindrical\nshapes. We evaluate analytically the coefficients of order two in density of\nthe wall-fluid surface tension $\\gamma$ and analyze the curvature contributions\nto the free energy. Emphasis is in bending and Gaussian rigidities, which are\nfound analytically at order two in density. Their contribution to $\\gamma(R)$\nand the accuracy of different truncation procedures to the low curvature\nexpansion are discussed. Finally, several universal relations that apply to\nlow-density fluids are analyzed."
    },
    {
        "anchor": "Deformation of an Amorphous Polymer during the\n  Fused-Filament-Fabrication Method for Additive Manufacturing: 3D printing is rapidly becoming an effective means of prototyping and\ncreating custom consumer goods. The most common method for printing a polymer\nmelt is fused filament fabrication (FFF), and involves extrusion of a\nthermoplastic material through a heated nozzle; the material is then built up\nlayer-by-layer to fabricate a three-dimensional object. Under typical printing\nconditions the melt experiences high strain rates within the FFF nozzle, which\nare able to significantly stretch and orient the polymer molecules. In this\npaper, we model the deformation of an amorphous polymer melt during the\nextrusion process, where the fluid must make a 90$^\\text{o}$ turn. The melt is\ndescribed by a modified version of the Rolie-Poly model, which allows for\nflow-induced changes in the entanglement density. The complex polymer\nconfigurations in the cross-section of a printed layer are quantified and\nvisualised. The deposition process involving the corner flow geometry dominates\nthe deformation and significantly disentangles the melt.",
        "positive": "The Relationship of Dynamical Heterogeneity to the Adam-Gibbs and Random\n  First-Order Transition Theories of Glass Formation: We carefully examine common measures of dynamical heterogeneity for a model\npolymer melt and test how these scales compare with those hypothesized by the\nAdam and Gibbs (AG) and random first-order transition (RFOT) theories of\nrelaxation in glass-forming liquids. To this end, we first analyze clusters of\nhighly mobile particles, the string-like collective motion of these mobile\nparticles, and clusters of relative low mobility. We show that the time scale\nof the high-mobility clusters and strings is associated with a diffusive time\nscale, while the low-mobility particles' time scale relates to a structural\nrelaxation time. We find a high degree of similarity in the geometrical\nstructure of these particle clusters. In particular, we show that the fractal\ndimensions of these clusters are consistent with those of swollen branched\npolymers or branched polymers with screened excluded-volume interactions. In\ncontrast, the fractal dimension of the strings crosses over from that of\nself-avoiding walks for small strings, to simple random walks for longer, {more\nstrongly interacting, strings, corresponding to flexible polymers with screened\nexcluded-volume interactions. We examine the appropriateness of identifying the\nsize scales of either mobile particle clusters or strings with the size of\ncooperatively rearranging regions (CRR) in the AG and RFOT theories. We find\nthat the string size appears to be the most consistent measure of CRR for both\nthe AG and RFOT models. Identifying strings or clusters with the \"mosaic\"\nlength of the RFOT model relaxes the conventional assumption that the \"entropic\ndroplets\" are compact. We also confirm the validity of the entropy formulation\nof the AG theory, constraining the exponent values of the RFOT theory. This\nconstraint, together with the analysis of size scales, enables us to estimate\nthe characteristic exponents of RFOT."
    },
    {
        "anchor": "Intermediate scattering function of an anisotropic Brownian circle\n  swimmer: Microswimmers exhibit noisy circular motion due to asymmetric propulsion\nmechanisms, their chiral body shape, or by hydrodynamic couplings in the\nvicinity of surfaces. Here, we employ the Brownian circle swimmer model and\ncharacterize theoretically the dynamics in terms of the directly measurable\nintermediate scattering function. We derive the associated Fokker-Planck\nequation for the conditional probabilities and provide an exact solution in\nterms of generalizations of the Mathieu functions. Different spatiotemporal\nregimes are identified reflecting the bare translational diffusion at large\nwavenumbers, the persistent circular motion at intermediate wavenumbers and an\nenhanced effective diffusion at small wavenumbers. In particular, the circular\nmotion of the particle manifests itself in characteristic oscillations at a\nplateau of the intermediate scattering function for wavenumbers probing the\nradius.",
        "positive": "Interaction anisotropy and the KPZ to KPZQ transition in particle\n  deposition at the edges of drying drops: The deposition process at the edge of evaporating colloidal drops varies with\nthe shape of suspended particles. Experiments with prolate ellipsoidal\nparticles suggest that the spatiotemporal properties of the deposit depend\nstrongly on particle aspect ratio. As the aspect ratio increases, the particles\nform less densely-packed deposits and the statistical behavior of the deposit\ninterface crosses over from the Kardar-Parisi-Zhang (KPZ) universality class to\nanother universality class which was suggested to be consistent with the KPZ\nplus quenched disorder. Here, we numerically study the effect of particle\ninteraction anisotropy on deposit growth. In essence, we model the ellipsoids,\nat the interface, as disk-like particles with two types of interaction patches\nthat correspond to specific features at the poles and equator of the ellipsoid.\nThe numerical results corroborate experimental observations and further suggest\nthat the deposition transition can stem from interparticle interaction\nanisotropy. Possible extensions of our model to other systems are also\ndiscussed."
    },
    {
        "anchor": "Ratcheting of driven attracting colloidal particles: Temporal density\n  oscillations and current multiplicity: We consider the unidirectional particle transport in a suspension of\ncolloidal particles which interact with each other via a pair potential having\na hard-core repulsion plus an attractive tail. The colloids are confined within\na long narrow channel and are driven along by a DC or an AC external potential.\nIn addition, the walls of the channel interact with the particles via a\nratchet-like periodic potential. We use dynamical density functional theory to\ncompute the average particle current. In the case of DC drive, we show that as\nthe attraction strength between the colloids is increased beyond a critical\nvalue, the stationary density distribution of the particles loses its stability\nleading to depinning and a time dependent density profile. Attraction induced\nsymmetry breaking gives rise to the coexistence of stable stationary density\nprofiles with different spatial periods and time-periodic density profiles,\neach characterized by different values for the particle current.",
        "positive": "Density anomalies and high-order jamming crossovers: Jamming crossovers occur at zero temperature in assemblies of particles\ninteracting via finite range repulsive potentials, when on increasing the\ndensity particles make contacts with those of subsequent coordination shells.\nDensity anomalies, including an increased diffusivity upon isothermal\ncompression and a negative thermal expansion coefficient, are the finite\ntemperature signatures of the jamming crossovers. In this manuscript we show\nthat the jamming crossovers are correlated to an increase of the non affine\nresponse of the system to density changes, and clarify that jammed systems\nevolve upon compression through subsequent Eshlby-like plastic instabilities."
    },
    {
        "anchor": "Quincke rotor dynamics in confinement: rolling and hovering: The Quincke effect is an electrohydrodynamic instability which gives rise to\na torque on a dielectric particle in a uniform DC electric field. Previous\nstudies reported that a sphere initially resting on the electrode rolls with\nsteady velocity. We experimentally find that in strong fields the rolling\nbecomes unsteady, with time-periodic velocity. Furthermore, we find another\nregime, where the rotating sphere levitates in the space between the\nelectrodes. Our experimental results show that the onset of Quincke rotation\nstrongly depends on particle confinement and the threshold for rolling is\nhigher compared to rotation in the hovering state.",
        "positive": "Maxwell viscoelastic dynamics of the DNA in the THz range: The attenuation of phonon modes of the DNA is due to the exchange of water\nmolecules adsorbed by a molecule of DNA and the bulk solvent. Using Maxwell's\nmechanism of relaxation and a simple lattice model of the DNA, we show that the\nattenuation tends to a constant value for phonon frequencies larger than the\ninverse residence time of water molecules. We come to the conclusion that in\nthe THz range the attenuation could be small enough to allow the propagation of\nthe phonon modes."
    },
    {
        "anchor": "Mean and Gaussian Curvature of Lipid Mesophases measured using molecular\n  dynamics: The ability to measure the mean and Gaussian curvature in lipid mesophases is\nimportant in our understanding of their formation and properties, and can be\nachieved both experimentally and computationally. Here we show that curvature\ncan be measured using Molecular Dynamics simulations, however the reliability\nof the results is highly dependent on the choice of fitting algorithm, the\natoms within the lipid membrane that are selected for fitting and the number of\natoms that are included in the fit. We compare the results of our method to the\nL${\\alpha}$ mesophase as previously studied, and subsequently extend the method\nto the Q$_{II}^{D}$ and H$_{II}$ mesophase, not previously studied in this way\ncomputationally, but whose curvatures are known both analytically and\nexperimentally. By systematically comparing our results, we demonstrate a\nrobust method which can be used in general to measure curvature.",
        "positive": "Electrorotation of colloidal suspensions: When a strong electric field is applied to a colloidal suspension, it may\ncause an aggregation of the suspended particles in response to the field. In\nthe case of a rotating field, the electrorotation (ER) spectrum can be modified\nfurther due to the local field effects arising from the many-particle system.\nTo capture the local field effect, we invoke the Maxwell-Garnett approximation\nfor the dielectric response. The hydrodynamic interactions between the\nsuspended particles can also modify the spin friction, which is a key to\ndetermine the angular velocity of ER. By invoking the spectral representation\napproach, we derive the analytic expressions for the characteristic frequency\nat which the maximum angular velocity of ER occurs. From the numerical\ncaculation, we find that there exist two sub-dispersions in the ER spectrum.\nHowever, the two characteristic frequencies are so close that the two peaks\nactually overlap and become a single broad peak. We report a detailed\ninvestigation of the dependence of the characteristic frequency and the\ndispersion strength of ER on various material parameters."
    },
    {
        "anchor": "A Reduced Landau-de Gennes Study for Nematic Equilibria in\n  Three-Dimensional Prisms: We model nematic liquid crystal configurations inside three-dimensional\nprisms, with a polygonal cross-section and Dirichlet boundary conditions on all\nprism surfaces. We work in a reduced Landau-de Gennes framework, and the\nDirichlet conditions on the top and bottom surfaces are special in the sense,\nthat they are critical points of the reduced Landau-de Gennes energy on the\npolygonal cross-section. The choice of the boundary conditions allows us to\nmake a direct correspondence between the three-dimensional Landau-de Gennes\ncritical points and pathways on the two-dimensional Landau-de Gennes solution\nlandscape on the polygonal cross-section. We explore this concept by means of\nasymptotic analysis and numerical examples, with emphasis on a cuboid and a\nhexagonal prism, focusing on three-dimensional multistability tailored by\ntwo-dimensional solution landscapes.",
        "positive": "Buckling mediated by mobile localized elastic excitations: Experiments reveal that structural transitions in thin sheets are mediated by\nthe passage of transient and stable mobile localized elastic excitations. These\n``crumples'' or ``d-cones'' nucleate, propagate, interact, annihilate, and\nescape. Much of the dynamics occurs on millisecond time scales. Nucleation\nsites correspond to regions where generators of the ideal unstretched surface\nconverge. Additional stable intermediate states illustrate two forms of\nquasistatic inter-crumple interaction through ridges or valleys. These\ninteractions create pairs from which extended patterns may be constructed in\nlarger specimens. The onset of localized transient deformation with increasing\nsheet size is correlated with a characteristic stable crumple size, whose\nmeasured scaling with thickness is consistent with prior theory and experiment\nfor localized elastic features in thin sheets. We offer a new theoretical\njustification of this scaling."
    },
    {
        "anchor": "Morphology of Nanoclusters and Nanopillars Formed in Nonequilibrium\n  Surface Growth for Catalysis Applications: We consider growth of nanoclusters and nanopillars in a model of surface\ndeposition and restructuring yielding morphologies of interest in designing\ncatalysis applications. Kinetic Monte Carlo numerical modeling yields examples\nof the emergence of FCC-symmetry surface features, allowing evaluation of the\nfraction of the resulting active sites with desirable properties, such as\n(111)-like coordination, as well as suggesting the optimal growth regimes.",
        "positive": "Shear-induced ordering of nano-pores and instabilities in concentrated\n  surfactant mesh phases: Mixed surfactant systems with strongly bound counterions show many\ninteresting phases such as the random mesh phase consisting of a disordered\narray of defects (water-filled nano-pores in the bilayers). The present study\naddresses the non-equilibrium phase transition of the random mesh phase under\nshear to an ordered mesh phase with a high degree of coherence between\nnano-pores in three-dimension. In-situ small-angle synchrotron X-ray study\nunder different shear stress conditions shows sharp Bragg peaks in the X-ray\ndiffraction, successfully indexed to the rhombohedral lattice with R$\\bar{3}$m\nspace group symmetry. The ordered mesh phase shows isomorphic twinning and\nbuckling at higher shear stress. Our experimental studies bring out rich\nnon-equilibrium phase transitions in concentrated cationic surfactant systems\nwith strongly bound counterions hitherto not well-explored and provide\nmotivation for a quantitative understanding."
    },
    {
        "anchor": "Force Induced DNA Melting: When pulled along the axis, double-strand DNA undergoes a large\nconformational change and elongates roughly twice its initial contour length at\na pulling force about 70 pN. The transition to this highly overstretched form\nof DNA is very cooperative. Applying force perpendicular to the DNA axis\n(unzipping), double-strand DNA can also be separated into two single-stranded\nDNA which is a fundamental process in DNA replication. We study the DNA\noverstretching and unzipping transition using fully atomistic molecular\ndynamics (MD) simulations and argue that the conformational changes of double\nstrand DNA associated with either of the above mentioned processes can be\nviewed as force induced DNA melting. As the force at one end of the DNA is\nincreased the DNA start melting abruptly/smoothly after a critical force\ndepending on the pulling direction. The critical force fm, at which DNA melts\ncompletely decreases as the temperature of the system is increased. The melting\nforce in case of unzipping is smaller compared to the melting force when the\nDNA is pulled along the helical axis. In the cases of melting through\nunzipping, the double-strand separation has jumps which correspond to the\ndifferent energy minima arising due to different base pair sequence. The\nfraction of Watson-Crick base pair hydrogen bond breaking as a function of\nforce does not show smooth and continuous behavior and consists of plateaus\nfollowed by sharp jumps.",
        "positive": "A Case Study of Sedimentation of Charged Colloids: The Primitive Model\n  and the Effective One-Component Approach: Sedimentation-diffusion equilibrium density profiles of suspensions of\ncharge-stabilized colloids are calculated theoretically and by Monte Carlo\nsimulation, both for a one-component model of colloidal particles interacting\nthrough pairwise screened-Coulomb repulsions and for a three-component model of\ncolloids, cations, and anions with unscreened-Coulomb interactions. We focus on\na state point for which experimental measurements are available [C.P. Royall et\nal., J. Phys.: Cond. Matt. {\\bf 17}, 2315 (2005)]. Despite the apparently\ndifferent picture that emerges from the one- and three-component model\n(repelling colloids pushing each other to high altitude in the former, versus a\nself-generated electric field that pushes the colloids up in the latter), we\nfind similar colloidal density profiles for both models from theory as well as\nsimulation, thereby suggesting that these pictures represent different view\npoints of the same phenomenon. The sedimentation profiles obtained from an\neffective one-component model by MC simulations and theory, together with MC\nsimulations of the multi-component primitive model are consistent among\nthemselves, but differ quantitatively from the results of a theoretical\nmulti-component description at the Poisson-Boltzmann level. We find that for\nsmall and moderate colloid charge the Poisson-Boltzmann theory gives profiles\nin excellent agreement with the effective one-component theory if a smaller\neffective charge is used. We attribute this discrepancy to the poor treatment\nof correlations in the Poisson-Boltzmann theory."
    },
    {
        "anchor": "Overdamped thermal ratchets in one and more dimensions. Kinesin\n  transport and protein folding: The overdamped thermal ratchet driven by an external (Orstein-Uhlenbeck)\nnoise is revisited. The ratchet we consider is unbounded in space and not\nnecessarily periodic . We briefly discuss the conditions under which current is\nobtained by analyzing the corresponding Fokker-Planck equation and its lack of\nstationary states. Next, two examples in more than one dimension and related to\nbiological systems are presented. First, a two-dimensional model of a ``kinesin\nprotein'' on a ``microtubule'' is analyzed and, second, we suggest that a\nratchet mechanism may be behind the folding of proteins; the latter is\nelaborated with a multidimensional ratchet model.",
        "positive": "Structure and Osmotic Pressure of Ionic Microgel Dispersions: We investigate structural and thermodynamic properties of aqueous dispersions\nof ionic microgels -- soft colloidal gel particles that exhibit unusual phase\nbehavior. Starting from a coarse-grained model of microgel macroions as charged\nspheres that are permeable to microions, we perform simulations and theoretical\ncalculations using two complementary implementations of Poisson-Boltzmann (PB)\ntheory. Within a one-component model, based on a linear-screening approximation\nfor effective electrostatic pair interactions, we perform molecular dynamics\nsimulations to compute macroion-macroion radial distribution functions, static\nstructure factors, and macroion contributions to the osmotic pressure. For the\nsame model, using a variational approximation for the free energy, we compute\nboth macroion and microion contributions to the osmotic pressure. Within a\nspherical cell model, which neglects macroion correlations, we solve the\nnonlinear PB equation to compute microion distributions and osmotic pressures.\nBy comparing the one-component and cell model implementations of PB theory, we\ndemonstrate that the linear-screening approximation is valid for moderately\ncharged microgels. By further comparing cell model predictions with simulation\ndata for osmotic pressure, we chart the cell model's limits in predicting\nosmotic pressures of salty dispersions."
    },
    {
        "anchor": "Stable oil-laden foams: Formation and evolution: The interaction between oil and foam has been the subject of various studies.\nIndeed, oil can be an efficient defoaming agent, which can be highly valuable\nin various industrial applications where undesired foaming may occur, as seen\nin jet-dyeing processes or waste water treatment plant. However, oil and foam\ncan also constructively interact as observed in detergency, fire-fighting, food\nand petroleum industries, where oil can be in the foam structure or put into\ncontact with the foam without observing a catastrophic break-up of the foam.\nUnder specific physico-chemistry conditions, the oil phase can even be trapped\ninside the aqueous network of the foam, thus providing interesting complex\nmaterials made of three different fluid phases that we name oil-laden foam\n(OLF). In this review, we focus on such systems, with a special emphasis on dry\nOLF, i.e. with a total liquid volume fraction, $\\varepsilon$ smaller than 5%.\nWe first try to clarify the physical and chemical conditions for these systems\nto appear, we review the different techniques of the literature to obtain them.\nThen we discuss their structure and identify two different OLF morphologies,\nnamed foamed emulsion, in which small oil globules are comprised within the\nnetwork of the aqueous foam and biliquid foams, where the oil also comprised in\nthe aqueous foam network is continuous at the scale of several bubbles. Last,\nwe review the state of the art of their evolution in particular concerning\ntopological changes, coalescence, coarsening and drainage.",
        "positive": "Activity induced collapse and re-expansion of rigid polymers: We study the elastic properties of a rigid filament in a bath of\nself-propelled particles. We find that while fully flexible filaments swell\nmonotonically upon increasing the strength of the propelling force, rigid\nfilaments soften for moderate activities, collapse into metastable hairpins for\nintermediate strengths, and eventually re-expand when the strength of the\nactivity of the surrounding fluid is large. This collapse and re-expansion of\nthe filament with the bath activity is reminiscent of the behavior observed in\npolyelectrolytes in the presence of different concentrations of multivalent\nsalt."
    },
    {
        "anchor": "Progressive Collapse Mechanisms of Brittle and Ductile Framed Structures: In this paper, we study the progressive collapse of 3D framed structures made\nof reinforced concrete after the sudden loss of a column. The structures are\nrepresented by elasto-plastic Euler Bernoulli beams with elongation-rotation\nfailure threshold. We performed simulations using the Discrete Element Method\nconsidering inelastic collisions between the structural elements. The results\nshow what collapse initiation and impact-driven propagation mechanisms are\nactivated in structures with different geometric and mechanical features.\nNamely, we investigate the influence of the cross sectional size and\nreinforcement $\\alpha$ and of the plastic capacity $\\beta$ of the structural\nelements. We also study the final collapse extent and the fragment size\ndistribution and their relation to $\\alpha$, $\\beta$ and to the observed\ncollapse mechanisms. Finally, we compare the damage response of structures with\nsymmetric and asymmetric reinforcement in the beams.",
        "positive": "Mechanics from Calorimetry: A New Probe of Elasticity for Responsive\n  Hydrogels: Temperature-sensitive hydrogels based on polymers such as\npoly(N-isopropylacrylamide) (PNIPAM) undergo a volume phase transition in\nresponse to changes in temperature. During this transition, distinct changes in\nboth thermal and mechanical properties are observed. Here, we illustrate and\nexploit the inherent thermodynamic link between thermal and mechanical\nproperties by showing that the compressive elastic modulus of PNIPAM hydrogels\ncan be probed using differential scanning calorimetry. We validate our approach\nby using conventional osmotic compression tests. Our method could be\nparticularly valuable for determining the mechanical response of\nthermosensitive submicron-sized and/or oddly shaped particles, to which\nstandard methods are not readily applicable."
    },
    {
        "anchor": "Electrically driven dynamic three-dimensional solitons in nematic liquid\n  crystals: Electric field induced collective reorientation of nematic molecules placed\nbetween two flat parallel electrodes is of importance for both fundamental\nscience and practical applications. This reorientation is either homogeneous\nover the area of electrodes, as in liquid crystal displays, or periodically\nmodulated, as in the phenomenon called electroconvection1, similar to\nRayleigh-B\\'enard thermal convection. The question is whether the electric\nfield can produce spatially localized propagating solitons of molecular\norientation. Here we demonstrate electrically driven three-dimensional\nparticle-like solitons representing self-trapped waves of oscillating molecular\norientation. The solitons propagate with a very high speed perpendicularly to\nboth the electric field and the initial alignment direction. The propulsion is\nenabled by rapid collective reorientations of the molecules with the frequency\nof the applied electric field and by lack of fore-aft symmetry. The solitons\npreserve spatially-confined shapes while moving over distances hundreds of\ntimes larger than their size and survive collisions. During collisions, the\nsolitons show repulsions and attractions, depending on the impact parameter.\nThe solitons are topologically equivalent to the uniform state and have no\nstatic analogs, thus exhibiting a particle-wave duality. We anticipate the\nobservations to be a starting point for a broad range of studies since the\nsystem allows for a precise control over a broad range of parameters that\ndetermine the shape, propagation speed, and interactions of the solitons.",
        "positive": "Quasi-saddles as relevant points of the potential energy surface in the\n  dynamics of supercooled liquids: The supercooled dynamics of a Lennard-Jones model liquid is numerically\ninvestigated studying relevant points of the potential energy surface, i.e. the\nminima of the square gradient of total potential energy $V$. The main findings\nare: ({\\it i}) the number of negative curvatures $n$ of these sampled points\nappears to extrapolate to zero at the mode coupling critical temperature $T_c$;\n({\\it ii}) the temperature behavior of $n(T)$ has a close relationship with the\ntemperature behavior of the diffusivity; ({\\it iii}) the potential energy\nlandscape shows an high regularity in the distances among the relevant points\nand in their energy location. Finally we discuss a model of the landscape,\npreviously introduced by Madan and Keyes [J. Chem. Phys. {\\bf 98}, 3342\n(1993)], able to reproduce the previous findings."
    },
    {
        "anchor": "Dynamic crossover scaling in polymer solutions: The crossover region in the phase diagram of polymer solutions, in the regime\nabove the overlap concentration, is explored by Brownian Dynamics simulations,\nto map out the universal crossover scaling functions for the gyration radius\nand the single-chain diffusion constant. Scaling considerations, our simulation\nresults, and recently reported data on the polymer contribution to the\nviscosity obtained from rheological measurements on DNA systems, support the\nassumption that there are simple relations between these functions, such that\nthey can be inferred from one another.",
        "positive": "Elastic models of the glass transition applied to a liquid with density\n  anomalies: Elastic models of the glass transition relate the relaxation dynamics and the\nelastic properties of structural glasses. They are based on the assumption that\nthe relaxation dynamics occurs through activated events in the energy landscape\nwhose energy scale is set by the elasticity of the material. Here we\ninvestigate whether such elastic models describe the relaxation dynamics of\nsystems of particles interacting via a purely repulsive harmonic potential,\nfocusing on a volume fraction and temperature range that is characterized by\nentropy--driven water--like density anomalies. We do find clear correlations\nbetween relaxation time and diffusivity on the one hand, and plateau shear\nmodulus and Debye--Waller factor on the other, thus supporting the validity of\nelastic models of the glass transition. However, we also show that the plateau\nshear modulus is not related to the features of the underlying energy landscape\nof the system, at variance with recent results for power--law potentials. This\nchallenges the common potential energy landscape interpretation of elastic\nmodels."
    },
    {
        "anchor": "The directional contact distance of two ellipsoids: Coarse-grained\n  potentials for anisotropic interactions: We obtain the distance of closest approach of the surfaces of two arbitrary\nellipsoids valid at any orientation and separation, measured along their\ninter-center vector. This directional distance is derived from the Elliptic\nContact Function. The geometric meaning behind this approach is clarified. An\nelliptic pair potential for modelling arbitrary mixtures of elliptic particles,\nwhether hard or soft, is proposed based on this distance. Comparisons to\nGay-Berne potentials are discussed. Analytic expressions for the forces and\ntorques acting on the elliptic particles are given.",
        "positive": "Oriented Active Solids: We present a complete analysis of the linearised dynamics of active solids\nwith orientational order, taking into account a hitherto overlooked consequence\nof rotation invariance. Our predictions include the possibility of stable\nactive solids with quasi-long-range order in two dimensions and long-range\norder in three dimensions, generic instability of the solid for one sign of\nactive forcing, and the instability of the orientationally ordered phase in\nmomentum-conserved systems for large active forcing irrespective of its sign."
    },
    {
        "anchor": "Nonlinear elasticity of semiflexible filament networks: We develop a continuum theory for equilibrium elasticity of a network of\ncrosslinked semiflexible filaments, spanning the full range between flexible\nentropy-driven chains to stiff athermal rods. We choose the 3-chain\nconstitutive model over several plausible candidates, and derive analytical\nexpressions for the elastic energy at arbitrary strain, with the corresponding\nstress-strain relationship. The theory fits well to a wide range of\nexperimental data on simple shear in different filament networks,\nquantitatively matching the differential shear modulus variation with stress,\nwith only two adjustable parameters (which represent the filament stiffness and\npre-tension in the network, respectively). The general theory accurately\ndescribes the crossover between the positive and negative Poynting effect\n(normal stress on imposed shear) on increasing the stiffness of filaments\nforming the network.",
        "positive": "Nonlinear atom-optical delta-kicked harmonic oscillator using a\n  Bose-Einstein condensate: We experimentally investigate the atom-optical delta-kicked harmonic\noscillator for the case of nonlinearity due to collisional interactions present\nin a Bose-Einstein condensate. A Bose condensate of rubidium atoms tightly\nconfined in a static harmonic magnetic trap is exposed to a one-dimensional\noptical standing-wave potential that is pulsed on periodically. We focus on the\nquantum anti-resonance case for which the classical periodic behavior is simple\nand well understood. We show that after a small number of kicks the dynamics is\ndominated by dephasing of matter wave interference due to the finite width of\nthe condensate's initial momentum distribution. In addition, we demonstrate\nthat the nonlinear mean-field interaction in a typical harmonically confined\nBose condensate is not sufficient to give rise to chaotic behavior."
    },
    {
        "anchor": "Marginally jammed states of hard disks in a one-dimensional channel: We have studied a class of marginally jammed states in a system of hard disks\nconfined in a narrow channel---a quasi-one-dimensional system---whose exponents\nare not those predicted by theories valid in the infinite dimensional limit.\nThe exponent $\\gamma$ which describes the distribution of small gaps takes the\nvalue $1$ rather than the infinite dimensional value $0.41269\\dots$. Our work\nshows that there exist jammed states not found within the tiling approach of\nAshwin and Bowles. The most dense of these marginal states is an unusual state\nof matter that is asymptotically crystalline.",
        "positive": "Ferroelectric-ferroelastic phase transition in a nematic liquid crystal: Ferroelectric ordering in liquids is a fundamental question of physics. Here,\nwe show that ferroelectric ordering of the molecules causes formation of\nrecently reported splay nematic liquid-crystalline phase. As shown by\ndielectric spectroscopy, the transition between the uniaxial and the splay\nnematic phase has the characteristics of a ferroelectric phase transition,\nwhich drives an orientational ferroelastic transition via flexoelectric\ncoupling. The polarity of the splay phase was proven by second harmonic\ngeneration (SHG) imaging, which additionally allowed for determination of the\nsplay modulation period to be of the order of 5 - 10 microns, also confirmed by\npolarized optical microscopy. The observations can be quantitatively described\nby a Landau-de Gennes type of macroscopic theory."
    },
    {
        "anchor": "Binary superlattice design by controlling DNA-mediated interactions: Most binary superlattices created using DNA functionalization or other\napproaches rely on particle size differences to achieve compositional order and\nstructural diversity. Here we study two-dimensional (2D) assembly of\nDNA-functionalized micron-sized particles (DFPs), and employ a strategy that\nleverages the tunable disparity in interparticle interactions, and thus\nenthalpic driving forces, to open new avenues for design of binary\nsuperlattices that do not rely on the ability to tune particle size (i.e.,\nentropic driving forces). Our strategy employs tailored blends of complementary\nstrands of ssDNA to control interparticle interactions between micron-sized\nsilica particles in a binary mixture to create compositionally diverse 2D\nlattices. We show that the particle arrangement can be further controlled by\nchanging the stoichiometry of the binary mixture in certain cases. With this\napproach, we demonstrate the abil- ity to program the particle assembly into\nsquare, pentagonal, and hexagonal lattices. In addition, different particle\ntypes can be compositionally ordered in square checkerboard and hexagonal -\nalternating string, honeycomb, and Kagome arrangements.",
        "positive": "Role of electrostatics in the texture of islands in free standing\n  ferroelectric liquid crystal films: Curved textures of ferroelectric smectic C* liquid crystals produce space\ncharge when they involve divergence of the spontaneous polarization field.\nImpurity ions can partially screen this space charge, reducing long range\ninteractions to local ones. Through studies of the textures of islands on very\nthin free-standing smectic films, we see evidence of this effect, in which\nmaterials with a large spontaneous polarization have static structures\ndescribed by a large effective bend elastic constant. To address this issue, we\ncalculated the electrostatic free energy of a free standing film of\nferroelectric liquid crystal, showing how the screened coulomb interaction\ncontributes a term to the effective bend elastic constant, in the static long\nwavelength limit. We report experiments which support the main features of this\nmodel."
    },
    {
        "anchor": "Estimate of the number of fragments formed during the rapid radial\n  expansion of a ring: In recent paper (Goloveshkin and Myagkov 2014) we proposed a two-dimensional\nenergy-based model of fragmentation of rapidly expanding cylinder under plane\nstrain conditions. The model allowed one to estimate the average fragment\nlength and the number of fragments produced by ductile fracture of the\ncylinder. In present note we show that the proposed approach can be used to\nestimate the number of fragments in a problem of fragmentation of an expanding\nring.",
        "positive": "Free volume distributions inside a bidimensional granular medium: We investigate experimentally within a two-dimensional cell the distribution\nof the free volume associated either to single grains or to clusters of grains.\nOur main result is that the logarithm of the probability to find a free volume\nper grain v_N^f in a cluster of N grains scales as N^alpha g(v_N^f), with alpha\n= 0.75. We interpret this non extensive scaling factor N^alpha as an evidence\nfor the onset of long range correlations between the free volumes of individual\ngrains. We also discuss the possible relation between g(v_N^f) and Edwards\nentropy."
    },
    {
        "anchor": "Recent experimental probes of shear banding: Recent experimental techniques used to investigate shear banding are\nreviewed. After recalling the rheological signature of shear-banded flows, we\nsummarize the various tools for measuring locally the microstructure and the\nvelocity field under shear. Local velocity measurements using dynamic light\nscattering and ultrasound are emphasized. A few results are extracted from\ncurrent works to illustrate open questions and directions for future research.",
        "positive": "Do cavities matter? Hollow microgels resist crystallization: Solutions of microgels have been widely used as model systems to gain insight\ninto atomic condensed matter and complex fluids. We explore the thermodynamic\nphase behavior of hollow microgels, which are distinguished from conventional\ncolloids by possessing a central cavity. Small-angle neutron and X-ray\nscattering are used to probe hollow microgels in crowded environments. These\nmeasurements reveal an interplay between interpenetration and deswelling, and\nan unusual absence of crystals. Monte Carlo simulations of hollow microgel\nsolutions confirm that, due to the cavity, they form a supercooled liquid more\nstable than in the case of microgels with a crosslinked core."
    },
    {
        "anchor": "Tracer particles sense local stresses in an evolving multicellular\n  spheroid without affecting the anomalous dynamics of the cancer cells: Measurements of local stresses on the cancer cells (CCs), inferred by\nembedding inert compressible tracer particles (TPs) in a growing multicellular\nspheroid (MCS), show that pressure decreases monotonically as the distance from\nthe core of the MCS increases. How faithfully do the TPs report the local\nstresses in the CCs is an important question because pressure buildup in the\nMCS is dynamically generated due to CC division, which implies that the CC\ndynamics should be minimally altered by the TPs. Here using theory and\nsimulations, we show that although the TP dynamics is unusual, exhibiting\nsub-diffusive behavior on times less than the CC division times and\nhyper-diffusive dynamics on in the long-time limit, they do not affect the\nlong-time CC dynamics or the local CC stress distributions. The CC pressure\nprofile within the MCS, which decays from a high value at the core to the\nperiphery, is almost identical with and without the TPs. That the TPs have\ninsignificant effect on the local stresses in the MCS implies that they are\nreliable reporters of the CC microenvironment.",
        "positive": "Modelling the helical-flexo-electro-optic effect: The helical-flexo-electro-optic effect shows interesting in-plane\nelectro-optic switching behaviour due to flexoelectric coupling with applied\nelectric fields. Previous understanding of the behaviour has been generally\nbased on an analytic approach which makes certain assumptions about the\nuniformity of the helical structure and the induced tilt angle under field\napplication. Here we remove these assumptions and develop a perturbative\napproximation to describe the structure in more detail. We also use a numerical\nmethod to investigate the behaviour in regimes where the perturbative approach\nis inappropriate. The impact of variation in elastic constants and dielectric\nanisotropy is investigated. We find that dielectric behaviour in particular can\nlead to substantial differences between the tilt angle obtained here and those\nobtained using previous analytic models."
    },
    {
        "anchor": "Comment on \"Flexibility of short DNA helices with finite-length effect:\n  From base pairs to tens of base pairs\": While analyzing the persistence length of DNA atomistic simulations Wu et al.\n[J. Chem. Phys. 142, 125103 (2015)] introduced an empirical formula to account\nfor the observed length-dependence. In particular they found that the\npersistence length increases with the distance. Here, we derive the formula by\nWu et al. using a non-local twistable wormlike chain which introduces couplings\nbetween distal sites. Finally, we show that the same formula can account for\nthe length-scale dependence of the torsional persistence length and is, in\nfact, applicable to any kind of polymer model with non-local couplings.",
        "positive": "Shape dependent phoretic propulsion of slender active particles: We theoretically study the self-propulsion of a thin (slender) colloid driven\nby asymmetric chemical reactions on its surface at vanishing Reynolds number.\nUsing the method of matched asymptotic expansions, we obtain the colloid\nself-propulsion velocity as a function of its shape and surface\nphysico-chemical properties. The mechanics of self-phoresis for rod-like\nswimmers has a richer spectrum of behaviours than spherical swimmers due to the\npresence of two small length scales, the slenderness of the rod and the width\nof the slip layer. This leads to subtleties in taking the limit of vanishing\nslenderness. As a result, even for very thin rods, the distribution of\ncurvature along the surface of the swimmer, namely its shape, plays a\nsurprising role in determining the efficiency of propulsion. We find that thin\ncylindrical self-phoretic swimmers with blunt ends move faster than thin\nprolate spheroid shaped swimmers with the same aspect ratio."
    },
    {
        "anchor": "Fano resonances with discrete breathers: A theoretical study of linear wave scattering by time-periodic spatially\nlocalized excitations (discrete breathers (DB)) is presented. We obtain that\nthe wave propagation is strongly influenced by a local coupling between an open\nand closed channels generated by the DB. A peculiar effect of total reflection\noccurs due to a Fano resonance when a localized state originating from closed\nchannels resonates with the open channel. For the discrete nonlinear\nSchroedinger chain we provide with an analytical result for the frequency\ndependence of the transmission coefficient, including the possibility of\nresonant reflection. We extend the analysis to chains of weakly coupled\nanharmonic oscillators and discuss the relevance of the effect for electronic\ntransport spectroscopy of mesoscopic systems.",
        "positive": "Relaxation dynamics and long-time tails explain shear-induced diffusion\n  of soft athermal particles near jamming: We numerically study shear-induced diffusion of soft athermal particles in\ntwo dimensions. The Green-Kubo (GK) relation is applicable to diffusion\ncoefficient of the particles near jamming, where both mean squared particle\nvelocities and relaxation time included in the GK formula are well explained by\ncritical scaling. We show that auto-correlation functions of the transverse\nvelocities are stretched exponential if the system is below jamming or shear\nrate is large enough. However, if the system is above jamming and the shear\nrate is sufficiently small, the auto-correlations exhibit long-time tails such\nthat time integral in the GK formula diverges in two dimensions. We propose\nempirical scaling relations for the critical exponents and demonstrate that the\nlong-time tails cause finite size effects on the shear-induced diffusion\ncoefficient."
    },
    {
        "anchor": "General Mechanism for a Positive Temperature Entropy Crisis in\n  Stationary Metastable States: Thermodynamic Necessity and Confirmation by\n  Exact calculations: We study stationary metastable states(SMS's)using a restricted partition\nfunction formalism. The formalism ensures that SMS free energy exists all the\nway to T=0, and remains stable. We introduce the concept of the reality\ncondition, according to which the entropy $S(T)$ of a set of coupled degrees of\nfreedom must be non-negative. The entropy crisis, which does not affect\nstability, is identified as the violation of the reality condition. We identify\nand validate rigorously, using general thermodynamic arguments, the following\ngeneral thermodynamic mechanism behind the entropy crisis in SMS. The free\nenergy $F_{\\text{dis}}(T)$ of any SMS must be equal to the T=0 crystal free\nenergy $E_{0}$ at two different temperatures $T=0,$ and $T=T_{\\text{eq}}>0$.\nThus, the stability requires $F_{\\text{dis}}(T)$ to possess a maximum at an\nintermediate but a strictly positive temperature $T_{\\text{K}},$ where the\nenergy is $E=E_{\\text{K}}.$ The SMS branch below $T_{\\text{K}}$ gives the\nentropy crisis and must be replaced by hand by an ideal glass free energy of\nconstant energy $E_{\\text{K}},$ and vanishing entropy. Hence, $T_{\\text{K}}>0$\nrepresents the Kauzmann temperature. The ideal glass energy $E_{\\text{K}}$ is\nhigher than the crystal energy $E_{0}$ at absolute zero, which is in agreement\nwith the experimenatal fact that the extrapolated energy of a real glass at T=0\nis higher than its T=0 crystal energy. We confirm the general predictions by\ntwo exact calculations, one of which is not mean-field. The calculations\nclearly show that the notion of SMS is not only not vaccuous, but also not a\nconsequence of a mean-field analysis. They also show that certain folklore\ncannot be substantiated.",
        "positive": "Birth and decay of tensional wrinkles in hyperelastic sheets: We demonstrate with experiments that wrinkling in stretched latex sheets\noccur over finite strains, and that their amplitudes grow and then decay to\nzero over a greater range of applied strains compared with linear elastic\nmaterials. The wrinkles occur provided the sheet is sufficiently thin compared\nto its width, and only over a finite range of length-to-width ratios. We show\nwith simulations that the Mooney-Rivlin hyperelastic model describes the\nobserved growth and decay of the wrinkles in our experiments. The decrease of\nwavelength with applied tension is found to be consistent with a\nfar-from-threshold scenario proposed by Cerda and Mahadevan in 2003. However,\nthe amplitude is observed to decrease with increasing tensile load, in contrast\nwith the prediction of their original model. We address the crucial assumption\nof {\\it collapse of compressive stress}, as opposed to collapse of compressive\nstrain, underlying the far-from-threshold analysis, and test it by measuring\nthe actual arc-length of the stretched sheet in the transverse direction and\nits difference from the width of a planar projection of the wrinkled shape. Our\nexperiments and numerical simulations indicate a complete {\\it collapse of the\ncompressive stress}, and reveal that a proper implementation of the\nfar-from-threshold analysis is consistent with the non-monotonic dependence of\nthe amplitude on applied tensile load observed in experiments and simulations.\nThus, our work support and extend far-from-threshold analysis to the stretching\nproblem of rectangular hyperelastic sheets."
    },
    {
        "anchor": "Fundamental differences between glassy dynamics in two and three\n  dimensions: The two-dimensional freezing transition is very different from its\nthree-dimensional counterpart. In contrast, the glass transition is usually\nassumed to have similar characteristics in two and three dimensions. Using\ncomputer simulations we show that glassy dynamics in supercooled two- and\nthree-dimensional fluids are fundamentally different. Specifically, transient\nlocalization of particles upon approaching the glass transition is absent in\ntwo dimensions, whereas it is very pronounced in three dimensions. Moreover,\nthe temperature dependence of the relaxation time of orientational correlations\nis decoupled from that of the translational relaxation time in two dimensions\nbut not in three dimensions. Lastly, the relationships between the\ncharacteristic size of dynamically heterogeneous regions and the relaxation\ntime are very different in two and three dimensions. These results strongly\nsuggest that the glass transition in two dimensions is different than in three\ndimensions.",
        "positive": "Defects and Metric Anomalies in F\u00f6ppl-von K\u00e1rm\u00e1n Surfaces: A general framework is developed to study the deformation and stress response\nin F{\\\"o}ppl-von K{\\'a}rm{\\'a}n shallow shells for a given distribution of\ndefects, such as dislocations, disclinations, and interstitials, and metric\nanomalies, such as thermal and growth strains. The theory includes dislocations\nand disclinations whose defect lines can both pierce the two-dimensional\nsurface and lie within the surface. An essential aspect of the theory is the\nderivation of strain incompatibility relations for stretching and bending\nstrains with incompatibility sources in terms of various defect and metric\nanomaly densities. The incompatibility relations are combined with balance laws\nand constitutive assumptions to obtain the inhomogeneous F{\\\"o}ppl-von\nK{\\'a}rm{\\'a}n equations for shallow shells. Several boundary value problems\nare posed, and solved numerically, by first considering only dislocations and\nthen disclinations coupled with growth strains."
    },
    {
        "anchor": "Influence of frozen capillary waves on contact mechanics: Free surfaces of liquids exhibit thermally excited (capillary) surface waves.\nWe show that the surface roughness which results from capillary waves when a\nglassy material is cooled below the glass transition temperature can have a\nlarge influence on the contact mechanics between the solids. The theory suggest\na new explanation for puzzling experimental results [L. Bureau, T. Baumberger\nand C. Caroli, arXiv:cond-mat/0510232] about the dependence of the frictional\nshear stress on the load for contact between a glassy polymer lens and flat\nsubstrates. It also lend support for a recently developed contact mechanics\ntheory.",
        "positive": "Attraction of like-charged macroions in the strong-coupling limit: Like-charged macroions attract each other as a result of strong electrostatic\ncorrelations in the presence of multivalent counterions or at low temperatures.\nWe investigate the effective electrostatic interaction between i) two\nlike-charged rods and ii) two like-charged spheres using the recently\nintroduced strong-coupling theory, which becomes asymptotically exact in the\nlimit of large coupling parameter (i.e. for large counterion valency, low\ntemperature, or high surface charge density on macroions). Since we deal with\ncurved surfaces, an additional parameter, referred to as Manning parameter, is\nintroduced, which measures the ratio between the radius of curvature of\nmacroions to the Gouy-Chapman length and controls the counterion-condensation\nprocess that directly affects the effective interactions. For sufficiently\nlarge Manning parameters (weakly-curved surfaces), we find a strong long-ranged\nattraction between two macroions that form a closely-packed bound state with\nsmall surface-to-surface separation of the order of the counterion diameter in\nagreement with recent simulations. For small Manning parameters (highly-curved\nsurfaces), on the other hand, the equilibrium separation increases and the\nmacroions unbind from each other as the confinement volume increases to\ninfinity. This occurs via a continuous universal unbinding transition for two\ncharged rods at a threshold Manning parameter of 2/3, while the transition is\ndiscontinuous for spheres because of a pronounced potential barrier at\nintermediate distances."
    },
    {
        "anchor": "Collective dynamics of chemically active particles trapped at a fluid\n  interface: Chemically active colloids generate changes in the chemical composition of\ntheir surrounding solution and thereby induce flows in the ambient fluid which\naffect their dynamical evolution. Here we study the many-body dynamics of a\nmonolayer of active particles trapped at a fluid-fluid interface. To this end\nwe consider a mean-field model which incorporates the direct pair interaction\n(including also the capillary interaction which is caused specifically by the\ninterfacial trapping) as well as the effect of hydrodynamic interactions\n(including the Marangoni flow induced by the response of the interface to the\nchemical activity). The values of the relevant physical parameters for typical\nexperimental realizations of such systems are estimated and various scenarios,\nwhich are predicted by our approach for the dynamics of the monolayer, are\ndiscussed. In particular, we show that the chemically-induced Marangoni flow\ncan prevent the clustering instability driven by the capillary attraction.",
        "positive": "Fluctuation-induced interactions in nematics with disordered anchoring\n  energy: We examine fluctuation-induced (pseudo-Casimir) interactions in nematic\nliquid-crystalline films confined between two surfaces, where one of the\nsurfaces imposes a strong homeotropic anchoring (ensuring a uniform mean\ndirector profile), while the other one is assumed to be a chemically disordered\nsubstrate exhibiting an annealed, random distribution of anchoring energies. We\nemploy a saddle-point approximation to evaluate the free energy of interaction\nmediated between the two surfaces and investigate how the interaction force is\ninfluenced by the presence of disordered surface anchoring energy. It is shown\nthat the disorder results in a renormalization of the effective surface\nanchoring parameter in a way that it leads to quantitative and qualitative\nchanges (including a change of sign at intermediate inter-surface separations)\nin the pseudo-Casimir interaction force when compared with the interaction\nforce in the absence of disorder."
    },
    {
        "anchor": "Stochastic resonance in a suspension of magnetic dipoles under shear\n  flow: We show that a magnetic dipole in a shear flow under the action of an\noscillating magnetic field displays stochastic resonance in the linear response\nregime. To this end, we compute the classical quantifiers of stochastic\nresonance, i.e. the signal to noise ratio, the escape time distribution, and\nthe mean first passage time. We also discuss limitations and role of the linear\nresponse theory in its applications to the theory of stochastic resonance.",
        "positive": "Coupling atomistic and continuum hydrodynamics through a mesoscopic\n  model: application to liquid water: We have conducted a triple-scale simulation of liquid water by concurrently\ncoupling atomistic, mesoscopic, and continuum models of the liquid. The\npresented triple-scale hydrodynamic solver for molecular liquids enables the\ninsertion of large molecules into the atomistic domain through a mesoscopic\nregion. We show that the triple-scale scheme is robust against the details of\nthe mesoscopic model owing to the conservation of linear momentum by the\nadaptive resolution forces. Our multiscale approach is designed for molecular\nsimulations of open domains with relatively large molecules, either in the\ngrand canonical ensemble or under non-equilibrium conditions."
    },
    {
        "anchor": "A texture tensor to quantify deformations: Under mechanical deformation, most materials exhibit both elastic and fluid\n(or plastic) responses. No existing formalism derived from microscopic\nprinciples encompasses both their fluid-like and solid-like aspects. We define\nthe {\\it statistical texture tensor} to quantify the intuitive notion of stored\ndeformation. This tensor links microscopic and macroscopic descriptions of the\nmaterial, and extends the definition of elastic strain.",
        "positive": "Memory effects in tumbling nematics of 8CB liquid crystals: Particle tracking with a 0.98$\\mu$m silica sphere is used in determining\nprecessional motion of nematic director in nematic phase of 8CB liquid\ncrystals, as it probes those oriented structures which are of the same\nwavelength as of the sphere size. Velocity auto correlation(VACF) is used in\ndetermining those structures in both parallel and perpendicular orientations to\nthe neamatic director. Further, a generic approach by considering the time\ndependent harmonic oscillator motions is used to analyze the VACF distribution\nfunction. This approach leads to observe a transition in the structures of\nnematic phase that are comparable to transformations from underdamped harmonic\noscillator motion to critically damped motion. Also, we measured the\nmicrostructural properties and calculated micromechanical properties. The\nexperimental analysis approach used here for 8CB liquid crystals helps to\nunderstand and characterize the general dynamic behavior of complex fluids.\nWith this analysis, `dynamics of complex fluids' becomes no more `complex'."
    },
    {
        "anchor": "Monolayer Structure of Supramolecular Antagonistic Salt Aggregates: The speculated presence of monomolecular lamellae of antagonistic salts in\noil-water mixtures has left several open questions besides their hypothetical\nexistence, including their microscopic structure and stabilization mechanism.\nHere, we simulate the spontaneous formation of supramolecular aggregates of the\nantagonistic salt sodium tetraphenylborate (NaBPh$_4$) in water and\n3-methylpyridine (3-MP) at the atomistic level. We show that, indeed, the\nlamellae are formed by a monomolecular layer of the anion, enveloped by 3-MP\nand hydrated sodium counterions. To understand which thermodynamic forces drive\nthe aggregation, we compare the full-atomistic model with a simplified one for\nthe salt and show that the strong hydrophobic effect granted by the large\nexcluded volume of the anion, together with electrostatic repulsion, suffice to\nexplain the stability of the monomolecular lamellae.",
        "positive": "How irreversible are steady-state trajectories of a trapped active\n  particle?: The defining feature of active particles is that they constantly propel\nthemselves by locally converting chemical energy into directed motion. This\nactive self-propulsion prevents them from equilibrating with their thermal\nenvironment (e.g., an aqueous solution), thus keeping them permanently out of\nequilibrium. Nevertheless, the spatial dynamics of active particles might share\ncertain equilibrium features, in particular in the steady state. We here focus\non the time-reversal symmetry of individual spatial trajectories as a distinct\nequilibrium characteristic. We investigate to what extent the steady-state\ntrajectories of a trapped active particle obey or break this time-reversal\nsymmetry. Within the framework of active Ornstein-Uhlenbeck particles we find\nthat the steady-state trajectories in a harmonic potential fulfill path-wise\ntime-reversal symmetry exactly, while this symmetry is typically broken in\nanharmonic potentials."
    },
    {
        "anchor": "Novel Experimentally Observed Phenomena in Soft Matter: Soft materials such as colloidal suspensions, polymer solutions and liquid\ncrystals are constituted by mesoscopic entities held together by weak forces.\nTheir mechanical moduli are several orders of magnitude lower than those of\natomic solids. The application of small to moderate stresses to these materials\nresults in the disruption of their microstructures. The resulting flow is\nnon-Newtonian and is characterised by features such as shear rate-dependent\nviscosities and non-zero normal stresses. This article begins with an\nintroduction to some unusual flow properties displayed by soft matter.\nExperiments that report a spectrum of novel phenomena exhibited by these\nmaterials, such as turbulent drag reduction, elastic turbulence, the formation\nof shear bands and the existence of rheological chaos, flow-induced\nbirefringence and the unusual rheology of soft glassy materials, are reviewed.\nThe focus then shifts to observations of the liquid-like response of granular\nmedia that have been subjected to external forces. The article concludes with\nexamples of the patterns that emerge when certain soft materials are vibrated,\nor when they are displaced with Newtonian fluids of lower viscosities.",
        "positive": "The shrinking instability of toroidal liquid droplets in the Stokes flow\n  regime: We analyze the stability and dynamics of toroidal liquid droplets. In\naddition to the Rayleigh instabilities akin to those of a cylindrical droplet\nthere is a shrinking instability that is unique to the topology of the torus\nand dominates in the limit that the aspect ratio is near one (fat tori). We\nfirst find an analytic expression for the pressure distribution inside the\ndroplet. We then determine the velocity field in the bulk fluid, in the Stokes\nflow regime, by solving the biharmonic equation for the stream function. The\nflow pattern in the external fluid is analyzed qualitatively by exploiting\nsymmetries. This elucidates the detailed nature of the shrinking mode and the\nswelling of the cross-section following from incompressibility. Finally the\nshrinking rate of fat toroidal droplets is derived by energy conservation."
    },
    {
        "anchor": "Independent Ion Migration in Suspensions of Strongly Interacting Charged\n  Colloidal Spheres: We report on sytematic measurements of the low frequency conductivity in\naequous supensions of highly charged colloidal spheres. System preparation in a\nclosed tubing system results in precisely controlled number densities between\n1E16/m3 and 1E19/m^3 (packing fractions between 1E-7 and 1E-2) and electrolyte\nconcentrations between 1E-7 and 1E-3 mol/l. Due to long ranged Coulomb\nrepulsion some of the systems show a pronounced fluid or crystalline order.\nUnder deionized conditions we find s to depend linearily on the packing\nfraction with no detectable influence of the phase transitions. Further at\nconstant packing fraction s increases sublinearily with increasing number of\ndissociable surface groups N. As a function of c the conductivity shows\npronounced differences depending on the kind of electrolyte used. We propose a\nsimple yet powerful model based on independent migration of all species present\nand additivity of the respective conductivity contributions. It takes account\nof small ion macro-ion interactions in terms of an effectivly transported\ncharge. The model successfully describes our qualitatively complex experimental\nobservations. It further facilitates quantitative estimates of conductivity\nover a wide range of particle and experimental parameters.",
        "positive": "Enhanced diffusion and anomalous transport of magnetic colloids driven\n  above a two-state flashing potential: We combine experiment and theory to investigate the diffusive and\nsubdiffusive dynamics of paramagnetic colloids driven above a two-state\nflashing potential. The magnetic potential was realized by periodically\nmodulating the stray field of a magnetic bubble lattice in a uniaxial ferrite\ngarnet film. At large amplitudes of the driving field, the dynamics of\nparticles resembles an ordinary random walk with a frequency-dependent\ndiffusion coefficient. However, subdiffusive and oscillatory dynamics at short\ntime scales is observed when decreasing the amplitude. We present a persistent\nrandom walk model to elucidate the underlying mechanism of motion, and perform\nnumerical simulations to demonstrate that the anomalous motion originates from\nthe dynamic disorder in the structure of the magnetic lattice, induced by\nslightly irregular shape of bubbles."
    },
    {
        "anchor": "Self-Organized Criticality in Proteins: Hydropathic Roughening Profiles\n  of G-Protein Coupled Receptors: Proteins appear to be the most dramatic natural example of self-organized\ncriticality (SOC), a concept that explains many otherwise apparently unlikely\nphenomena. Protein conformational functionality is often dominated by\nlong-range hydro(phobic/philic) interactions which both drive protein\ncompaction and mediate protein-protein interactions. Superfamily transmembrane\nGPCR are the largest family of proteins in the human genome; their amino acid\nsequences form the largest data base for protein-membrane interactions. While\nthere are now structural data on the heptad transmembrane structures of\nrepresentatives of several heptad families, here we show that fresh insights\ninto global and some local chemical trends in GPCR properties can be obtained\naccurately from sequences alone, especially by separating the extracellular and\ncytoplasmic loops from transmembrane segments. The global mediation of\nlong-range water-protein interactions occurs in conjunction with modulation of\nthese interactions by roughened interfaces. Hydropathic roughening profiles are\ndefined here solely in terms of amino acid sequences, and knowledge of protein\ncoordinates is not required. Roughening profiles both for GPCR and some simpler\nprotein families display accurate and transparent connections to protein\nfunctionality.",
        "positive": "Capturing Strain Stiffening Using Volume Controlled Cavity Expansion: Strain-stiffening is a well-documented behavior in soft biological materials\nsuch as liver and brain tissue. Measuring and characterizing this nonlinear\nresponse, which is commonly considered as a mechanism for damage prevention, is\nof great interest to engineers for design of better biomimetic materials, and\nto physicians for diagnostic purposes. However, probing the elastic response of\nsoft or biological materials at large deformation in their natural habitat, is\nan arduous task. Here, we present the Volume Controlled Cavity Expansion (VCCE)\ntechnique as an in-vivo measurement method that offers the ability of\ncharacterizing the stiffening response of materials in addition to identifying\ntheir shear modulus. By employing minimal constitutive representations\ninvolving only two constants (Mooney-Rivlin, Gent, and Ogden) we show that for\nthe conventional PDMS samples, this technique and an accompanying data analysis\nmethod capture the shear modulus, as well as providing reliable measures of the\nstiffening behavior of the samples."
    },
    {
        "anchor": "Two measures of isochronal superposition: A liquid obeys isochronal superposition if its dynamics is invariant along\nthe isochrones in the thermodynamic phase diagram (the curves of constant\nrelaxation time). This paper introduces two quantitative measures of isochronal\nsuperposition. The measures are used to test the following six liquids for\nisochronal superposition: 1,2,6 hexanetriol, glycerol, polyphenyl ether,\ndiethyl phthalate, tetramethyl tetraphenyl trisiloxane, and dibutyl phthalate.\nThe latter four van der Waals liquids obey isochronal superposition to a higher\ndegree than the two hydrogen-bonded liquids. This is a predic- tion of the\nisomorph theory, and it confirms findings by other groups.",
        "positive": "Simple models of proteins with repulsive non-native contacts: The Go model is extended to the case when the non-native contact energies may\nbe either attractive or repulsive. The folding temperature is found to increase\nwith the energy of non-native contacts. The repulsive non-native contact\nenergies may lead to folding at T=0 for some two-dimensional sequences and to\nreduction in complexity of disconnectivity graphs for local energy minima."
    },
    {
        "anchor": "Phase Separation Kinetics and Cluster Dynamics in Two-Dimensional Active\n  Dumbbell Systems: Molecular dynamics simulations were employed to investigate the phase\nseparation process of a two-dimensional active Brownian dumbbell model. We\nevaluated the time dependence of the typical size of the dense component using\nthe scaling properties of the structure factor, along with the averaged number\nof clusters and their radii of gyration. The growth observed is faster than in\nactive particle (disk) models, and this effect is further enhanced under\nstronger activity. Next, we focused on studying the hexatic order of the\nclusters. The length associated to the orientational order grows algebraically\nand faster than for active Brownian particles. Under weak active forces, most\nclusters exhibit a uniform internal orientational order. However, under strong\nforcing, large clusters consist of domains with different orientational orders.\nWe demonstrated that the latter configurations are not stable, and given\nsufficient time to evolve, they eventually reach homogeneous configurations as\nwell. No gas bubbles are formed within the clusters, even when there are\npatches of different hexatic order. Finally, attention was directed towards the\ngeometry and motion of the clusters themselves. By employing a tracking\nalgorithm, we showed that clusters smaller than the typical size at the\nobservation time exhibit regular shapes, while larger ones display fractal\ncharacteristics. In between collisions or break-ups, the clusters behave as\nsolid bodies. Their centers of mass undergo circular motion, with radii\nincreasing with the cluster size. The center of mass angular velocity equals\nthat of the constituents with respect to their center of mass. These\nobservations were rationalised with a simple mechanical model.",
        "positive": "Theory and simulation of short-range models of globular protein\n  solutions: We report theoretical and simulation studies of phase coexistence in model\nglobular protein solutions, based on short-range, central, pair potential\nrepresentations of the interaction among macro-particles. After reviewing our\nprevious investigations of hard-core Yukawa and generalised Lennard-Jones\npotentials, we report more recent results obtained within a DLVO-like\ndescription of lysozyme solutions in water and added salt. We show that a\none-parameter fit of this model based on Static Light Scattering and\nSelf-Interaction Chromatography data in the dilute protein regime, yields\ndemixing and crystallization curves in good agreement with experimental\nprotein-rich/protein-poor and solubility envelopes. The dependence of cloud and\nsolubility points temperature of the model on the ionic strength is also\ninvestigated. Our findings highlight the minimal assumptions on the properties\nof the microscopic interaction sufficient for a satisfactory reproduction of\nthe phase diagram topology of globular protein solutions."
    },
    {
        "anchor": "Emergence of active nematic behaviour in monolayers of isotropic cells: There is now growing evidence of the emergence and biological functionality\nof liquid crystal features, including nematic order and topological defects, in\ncellular tissues. However, how such features that intrinsically rely on\nparticle elongation, emerge in monolayers of cells with isotropic shapes is an\noutstanding question. In this article we present a minimal model of cellular\nmonolayers based on cell deformation and force transmission at the cell-cell\ninterface that explains the formation of topological defects and captures the\nflow-field and stress patterns around them. By including mechanical properties\nat the individual cell level, we further show that the instability that drives\nthe formation of topological defects and leads to active turbulence, emerges\nfrom a feedback between shape deformation and active driving. The model allows\nus to suggest new explanations for experimental observations in tissue\nmechanics, and to propose designs for future experiments.",
        "positive": "Instabilities and Topological Defects in Active Nematics: We study a continuum model of an extensile active nematic to show that\nmesoscale turbulence develops in two stages: (i) ordered regions undergo an\nintrinsic hydrodynamic instability generating walls, lines of stong bend\ndeformations, (ii) the walls relax by forming oppositely charged pairs of\ndefects. Both creation and annihilation of defect pairs reinstate nematic\nregions which undergo further instabilities, leading to a dynamic steady state.\nWe compare this with the development of active turbulence in a contractile\nactive nematic."
    },
    {
        "anchor": "A first-principle calculation of the XANES spectrum of Cu$^{2+}$ in\n  water: The progress in high performance computing we are witnessing today offers the\npossibility of accurate electron density calculations of systems in realistic\nphysico-chemical conditions. In this paper, we present a strategy aimed at\nperforming a first-principle computation of the low energy part of the X-ray\nAbsorption Spectroscopy (XAS) spectrum based on the density functional theory\ncalculation of the electronic potential. To test its effectiveness we apply the\nmethod to the computation of the X-ray Absorption Near Edge Structure part of\nthe XAS spectrum in the paradigmatic, but simple case of Cu2+ in water. In\norder to keep into account the effect of the metal site structure fluctuations\nin determining the experimental signal, the theoretical spectrum is evaluated\nas the average over the computed spectra of a statistically significant number\nof simulated metal site configurations. The comparison of experimental data\nwith theoretical calculations suggests that Cu2+ lives preferentially in a\nsquare-pyramidal geometry. The remarkable success of this approach in the\ninterpretation of XAS data makes us optimistic about the possibility of\nextending the computational strategy we have outlined to the more interesting\ncase of molecules of biological relevance bound to transition metal ions.",
        "positive": "Theoretical Puncture Mechanics of Soft Compressible Solids: Accurate prediction of the force required to puncture a soft material is\ncritical in many fields like medical technology, food processing, and\nmanufacturing. However, such a prediction strongly depends on our understanding\nof the complex nonlinear behavior of the material subject to deep indentation\nand complex failure mechanisms. Only recently we developed theories capable of\ncorrelating puncture force with material properties and needle geometry.\nHowever, such models are based on simplifications that seldom limit their\napplicability to real cases. One common assumption is the incompressibility of\nthe cut material, albeit no material is truly incompressible. In this paper we\npropose a simple model that accounts for linearly elastic compressibility, and\nits interplay with toughness, stiffness, and elastic strain-stiffening.\nConfirming previous theories and experiments, materials having high-toughness\nand low-modulus exhibit the highest puncture resistance at a given needle\nradius. Surprisingly, in these conditions, we observe that incompressible\nmaterials exhibit the lowest puncture resistance, where volumetric\ncompressibility can create an additional (strain) energy barrier to puncture.\nOur model provides a valuable tool to assess the puncture resistance of soft\ncompressible materials and suggests new design strategies for sharp needles and\npuncture-resistant materials."
    },
    {
        "anchor": "Third- and fourth-order constants of incompressible soft solids and the\n  acousto-elastic effect: Acousto-elasticity is concerned with the propagation of small-amplitude waves\nin deformed solids. Results previously established for the incremental\nelastodynamics of exact non-linear elasticity are useful for the determination\nof third- and fourth-order elastic constants, especially in the case of\nincompressible isotropic soft solids, where the expressions are particularly\nsimple. Specifically, it is simply a matter of expanding the expression for\n$\\rho v^2$, where $\\rho$ is the mass density and v the wave speed, in terms of\nthe elongation $e$ of a block subject to a uniaxial tension. The analysis shows\nthat in the resulting expression: $\\rho v^2 = a + be + ce^2$, say, $a$ depends\nlinearly on $\\mu$; $b$ on $\\mu$ and $A$; and $c$ on $\\mu$, $A$, and $D$, the\nrespective second-, third, and fourth-order constants of incompressible\nelasticity, for bulk shear waves and for surface waves.",
        "positive": "The Thermodynamics of Endosomal Escape and DNA Release from Lipoplexes: Complexes of cationic and neutral lipids and DNA (lipoplexes) are emerging as\npromising vectors for gene therapy applications. Their appeal stems from their\nnon pathogenic nature and the fact that they self-assemble under conditions of\nthermal equilibrium. Lipoplex adhesion to the cell plasma membrane initiates a\nthree-stage process termed transfection, consisting of (i) endocytosis, (ii)\nlipoplex breakdown, and (iii) DNA release followed by gene expression. As\nsuccessful transfection requires lipoplex degradation, it tends to be hindered\nby the lipoplex thermodynamic stability; nevertheless, it is known that the\ntransfection process may proceed spontaneously. Here, we use a simple model to\nstudy the thermodynamic driving forces governing transfection. We demonstrate\nthat after endocytosis [stage (i)], the lipoplex becomes inherently unstable.\nThis instability, which is triggered by interactions between the cationic\nlipids of the lipoplex and the anionic lipids of the enveloping plasma\nmembrane, is entropically controlled involving both remixing of the lipids and\ncounterions release. Our detailed calculation shows that the free energy gain\nduring stage (ii) is approximately linear in $\\Phi_+$, the mole fraction of\ncationic lipids in the lipoplex. This free energy gain, $\\Delta F$, reduces the\nbarrier for fusion between the enveloping and the lipoplex bilayers, which\nproduces a hole allowing for DNA release [stage (iii)]. The linear relationship\nbetween $\\Delta F$ and the fraction of cationic lipids explains the\nexperimentally observed exponential increase of transfection efficiency with\n$\\Phi_+$ in lamellar lipoplexes."
    },
    {
        "anchor": "Vortex Creation in Bose-Einstein Condensates by Laser Beam Vortex\n  Guiding: A technique for vortex creation in trapped Bose-Einstein condensates is\nsuggested: Vortices can be excited at the edge of a condensate and guided to\nthe center by a laser beam moving along a spiral trajectory. Numerical\nsimulations demonstrate the suggested technique. Parameter ranges for the\nmethod are given. Computer animations illustrate the dynamics of the guided\nvortices.",
        "positive": "Equation of State of Supercooled Water from the Sedimentation Profile: To study the coexistence of two liquid states of water within one simulation\nbox, we implement an equilibrium sedimentation method--which involves applying\na gravitational field to the system and measuring/calculating the resulting\ndensity profile in equilibrium. We simulate a system of particles interacting\nvia the ST2 potential, a model for water. We detect the coexistence of two\nliquid phases at low temperature."
    },
    {
        "anchor": "Relaxation in a Phase-separating Two-dimensional Active Matter System\n  with Alignment Interaction: Via computer simulations we study kinetics of pattern formation in a\ntwo-dimensional active matter system. Self-propulsion in our model is\nincorporated via the Vicsek-like activity, i.e., particles have the tendency of\naligning their velocities with the average directions of motion of their\nneighbors. In addition to this dynamic or active interaction, there exists\npassive inter-particle interaction in the model for which we have chosen the\nstandard Lennard-Jones form. Following quenches of homogeneous configurations\nto a point deep inside the region of coexistence between high and low density\nphases, as the systems exhibit formation and evolution of particle-rich\nclusters, we investigate properties related to the morphology, growth and\naging. A focus of our study is on the understanding of the effects of structure\non growth and aging. To quantify the latter we use the two-time order-parameter\nautocorrelation function. This correlation, as well as the growth, is observed\nto follow power-law time dependence, qualitatively similar to the scaling\nbehavior reported for passive systems. The values of the exponents have been\nestimated and discussed by comparing with the previously obtained numbers for\nother dimensions as well as with the new results for the passive limit of the\nconsidered model. We have also presented results on the effects of temperature\non the activity mediated phase separation.",
        "positive": "Run-to-Tumble Variability Controls the Surface Residence Times of ${\\it\n  E.~coli}$ Bacteria: Motile bacteria are known to accumulate at surfaces, eventually leading to\nchanges in bacterial motility and bio-film formation. We use a novel\ntwo-colour, three-dimensional Lagrangian tracking technique, to follow\nsimultaneously the body and the flagella of a wild-type ${\\it\nEscherichia~coli}$. We observe long surface residence times and surface escape\ncorresponding mostly to immediately antecedent tumbling. A motility model\naccounting for a large behavioural variability in run-time duration, reproduces\nall experimental findings and gives new insights into surface trapping\nefficiency."
    },
    {
        "anchor": "Wang-Landau algorithm for entropic sampling of arch-based microstates in\n  the volume ensemble of static granular packings: We implement the Wang-Landau algorithm to sample with equal probabilities the\nstatic configurations of a model granular system. The \"non-interacting rigid\narch model\" used is based on the description of static configurations by means\nof splitting the assembly of grains into sets of stable arches. This technique\nallows us to build the entropy as a function of the volume of the packing for\nlarge systems. We make a special note of the details that have to be considered\nwhen defining the microstates and proposing the moves for the correct sampling\nin these unusual models. We compare our results with previous exact\ncalculations of the model made at moderate system sizes. The technique opens a\nnew opportunity to calculate the entropy of more complex granular models.",
        "positive": "Self-Similarity and Energy Dissipation in Stepped Polymer Films: The surface of a thin liquid film with nonconstant curvature is unstable, as\nthe Laplace pressure drives a flow mediated by viscosity. We present the\nresults of experiments on one of the simplest variable curvature surfaces: a\nstepped polymer film. Height profiles are measured as a function of time for a\nvariety of molecular weights. The evolution of the profiles is shown to be\nself-similar. This self-similarity offers a precise measurement of the\ncapillary velocity by comparison with numerical solutions of the thin film\nequation. We also derive a master expression for the time dependence of the\nexcess free energy as a function of the material properties and film geometry.\nThe experiment and theory are in excellent agreement and indicate the\neffectiveness of stepped polymer films to elucidate nanoscale rheological\nproperties."
    },
    {
        "anchor": "Condensate localization in a quasi-periodic structure: We propose a set-up of optical laser beams by which one may realize a\nquasi-one-dimensional Fibonacci array of potential wells for a Bose-Einstein\ncondensate. We use a Bose-Hubbard tight-binding model to evaluate the transport\nof superfluid Rb87 atoms driven by a constant force through such an array. We\nshow that the minigaps that are generated in the spectral density-of-states by\nthe quasi-periodic disorder give rise to prominent localization effects, which\ncan be observed by measuring the tunnel output of matter into vacuum as a\nfunction of the intensity of the applied force.",
        "positive": "Smectic ordering in liquid crystal - aerosil dispersions II. Scaling\n  analysis: Liquid crystals offer many unique opportunities to study various phase\ntransitions with continuous symmetry in the presence of quenched random\ndisorder (QRD). The QRD arises from the presence of porous solids in the form\nof a random gel network. Experimental and theoretical work support the view\nthat for fixed (static) inclusions, quasi-long-range smectic order is destroyed\nfor arbitrarily small volume fractions of the solid. However, the presence of\nporous solids indicates that finite-size effects could play some role in\nlimiting long-range order. In an earlier work, the nematic - smectic-A\ntransition region of octylcyanobiphenyl (8CB) and silica aerosils was\ninvestigated calorimetrically. A detailed x-ray study of this system is\npresented in the preceding Paper I, which indicates that pseudo-critical\nscaling behavior is observed. In the present paper, the role of finite-size\nscaling and two-scale universality aspects of the 8CB+aerosil system are\npresented and the dependence of the QRD strength on the aerosil density is\ndiscussed."
    },
    {
        "anchor": "Nature of self-diffusion in two-dimensional fluids: Self-diffusion in a two-dimensional simple fluid is investigated by both\nanalytical and numerical means. We investigate the anomalous aspects of\nself-diffusion in two-dimensional fluids with regards to the mean square\ndisplacement, the time-dependent diffusion coefficient, and the velocity\nautocorrelation function using a consistency equation relating these\nquantities. We numerically confirm the consistency equation by extensive\nmolecular dynamics simulations for finite systems, corroborate earlier results\nindicating that the kinematic viscosity approaches a finite, non-vanishing\nvalue in the thermodynamic limit, and establish the finite size behavior of the\ndiffusion coefficient. We obtain the exact solution of the consistency equation\nin the thermodynamic limit and use this solution to determine the large time\nasymptotics of the mean square displacement, the diffusion coefficient, and the\nvelocity autocorrelation function. An asymptotic decay law of the velocity\nautocorrelation function resembles the previously known self-consistent form,\n$1/(t\\sqrt{\\ln t})$, however with a rescaled time.",
        "positive": "Bundle formation in parallel aligned polymers with competing\n  interactions: Aggregation of like-charged polymers is widely observed in biological and\nsoft matter systems. In many systems, bundles are formed when a short-range\nattraction of diverse physical origin like charge-bridging, hydrogen-bonding or\nhydrophobic interaction, overcomes the longer- range charge repulsion. In this\nLetter, we present a general mechanism of bundle formation in these systems as\nthe breaking of the translational invariance in parallel aligned polymers with\ncompeting interactions of this type. We derive a criterion for finite-sized\nbundle formation as well as for macroscopic phase separation (formation of\ninfinite bundles)."
    },
    {
        "anchor": "Nanochannels and nanodroplets in polymer membranes controlling ionic\n  transport: Polymer materials with low water uptake exhibit a highly heterogeneous\ninterior, characterized by water clusters in the form of nanodroplets and\nnanochannels. Here, based on our recent insights from computer simulations, we\nargue that water cluster structure has large implications for ionic transport\nand selective permeability in polymer membranes. Importantly, we demonstrate\nthat the two key quantities for transport, the ion diffusion and the solvation\nfree energy inside the polymer, are extremely sensitive to molecular details of\nthe water clusters. In particular, we highlight the significance of water\ndroplet interface potentials and the nature of hopping diffusion through\ntransient water channels. These mechanisms can be harvested and fine-tuned to\noptimize selectivity in ionic transport in a wide range of applications.",
        "positive": "Compaction dynamics in ductile granular media: Ductile compaction is common in many natural systems, but the temporal\nevolution of such systems is rarely studied. We observe surprising oscillations\nin the weight measured at the bottom of a self-compacting ensemble of ductile\ngrains. The oscillations develop during the first ten hours of the experiment,\nand usually persist through the length of an experiment (one week). The weight\noscillations are connected to the grain--wall contacts, and are directly\ncorrelated with the observed strain evolution and the dynamics of grain--wall\ncontacts during the compaction. Here, we present the experimental results and\ncharacteristic time constants of the system, and discuss possible reasons for\nthe measured weight oscillations."
    },
    {
        "anchor": "Understanding Enhanced Mechanical Stability of DNA in the Presence of\n  Intercalated Anticancer Drug: Implications for DNA Associated Processes: Most of the anticancer drugs bind to double-stranded DNA (dsDNA) by\nintercalative-binding mode. Although experimental studies have become available\nrecently, a molecular-level understanding of the interactions between the drug\nand dsDNA that lead to the stability of the intercalated drug is lacking. Of\nparticular interest are the modifications of the mechanical properties of dsDNA\nobserved in experiments. The latter could affect many biological functions,\nsuch as DNA transcription and replication. Here we probe, via all-atom\nmolecular dynamics (MD) simulations, change in the mechanical properties of\nintercalated drug-DNA complexes for two intercalators, daunomycin and ethidium.\nWe find that, upon drug intercalation, stretch modulus of DNA increases\nsignificantly, whereas its persistence length and bending modulus decrease.\nSteered MD simulations reveal that it requires higher forces to stretch the\nintercalated dsDNA complexes than the normal dsDNA. Adopting various pulling\nprotocols to study force-induced DNA melting, we find that the dissociation of\ndsDNA becomes difficult in the presence of intercalators. The results obtained\nhere provide a plausible mechanism of function of the anticancer drugs, i.e.,\nvia altering the mechanical properties of DNA. We also discuss long-time\nconsequences of using these drugs, which require further in vivo\ninvestigations.",
        "positive": "Identification of New Assembly Mode in the Heliconical Nematic Phase via\n  Tender Resonant X-ray Scattering: Helical structures are exciting and are utilized in numerous applications\nranging from biotechnology to displays to medicine. Accurate description and\nunderstanding of resonance effects in helical structures provides crucial\nknowledge on molecular packing beyond positional ordering. We exam-ined the\nmanifestation of resonance effects in a nematic phase with heliconical\nstructure, the so called twist bend nematic (NTB) via tender resonant X-ray\nscattering (TReXS) at the sulfur K-edge. We demonstrate for the first time\nquantitatively that the energy dependence of the scattering peak in the NTB\nphase follows the energy dependence of the complex refractive indices measured\nby X-ray absorption. This allows us to identify a new self-assembly mode for\nspecific sets of liquid crystal dimers in the NTB phase. We anticipate that new\navenues in the exploration of complex orientational structures both in static\nas well as in dynamic modes induced by external stimuli will be pursued."
    },
    {
        "anchor": "On the Concept of Static Structure Factor: We clarify the confusion in the expression of the static structure factor\nS(k) in the study of condensed matters and discuss its explicit form that can\nbe directly used in calculations and computer simulations.",
        "positive": "Localization dynamics of fluids in random confinement: The dynamics of two-dimensional fluids confined within a random matrix of\nobstacles is investigated using both colloidal model experiments and molecular\ndynamics simulations. By varying fluid and matrix area fractions in the\nexperiment, we find delocalized tracer particle dynamics at small matrix area\nfractions and localized motion of the tracers at high matrix area fractions. In\nthe delocalized region, the dynamics is subdiffusive at intermediate times, and\ndiffusive at long times, while in the localized regime, trapping in finite\npockets of the matrix is observed. These observations are found to agree with\nthe simulation of an ideal gas confined in a weakly correlated matrix. Our\nresults show that Lorentz gas systems with soft interactions are exhibiting a\nsmoothening of the critical dynamics and consequently a rounded\ndelocalization-to-localization transition."
    },
    {
        "anchor": "Glass transition of binary mixtures of dipolar particles in two\n  dimensions: We study the glass transition of binary mixtures of dipolar particles in two\ndimensions within the framework of mode-coupling theory, focusing in particular\non the influence of composition changes. In a first step, we demonstrate that\nthe experimental system of K\\\"onig et al. [Eur. Phys. J. E 18, 287 (2005)] is\nwell described by point dipoles through a comparison between the experimental\npartial structure factors and those from our Monte Carlo simulation. For such a\nmixture of point particles we show that there is always a plasticization\neffect, i.e. a stabilization of the liquid state due to mixing, in contrast to\nbinary hard disks. We demonstrate that the predicted plasticization effect is\nin qualitative agreement with experimental results. Furthermore, also some\ngeneral properties of the glass transition lines are discussed.",
        "positive": "Quadrupole terms in the Maxwell equations: Born energy, partial molar\n  volume and entropy of ions. Debye-H\u00fcckel theory in a quadrupolarizable\n  medium: A new equation of state relating the macroscopic quadrupole moment density\n$Q$ to the gradient of the field $\\nabla E$ in an isotropic fluid is derived:\n$Q = \\alpha_Q(\\nabla E - U \\nabla.E/3)$, where the quadrupolarizability\n$\\alpha_Q$ is proportional to the squared molecular quadrupole moment. Using\nthis equation of state, a generalized expression for the Born energy of an ion\ndissolved in quadrupolar solvent is obtained. It turns out that the potential\nand the energy of a point charge in a quadrupolar medium are finite. From the\nobtained Born energy, the partial molar volume and the partial molar entropy of\na dissolved ion follow. Both are compared to experimental data for a large\nnumber of simple ions in aqueous solutions. From the comparison the value of\nthe quadrupolar length $L_Q$ is determined, $L_Q = \\sqrt{\\alpha_Q/3\\epsilon}=\n1-2 {\\AA}$. Further, the extended Debye-H\\\"uckel model is generalized to ions\nin a quadrupolar solvent. If quadrupole terms are allowed in the macroscopic\nCoulomb law, they result in suppression of the gradient of the electric field.\nIn result, the electric double layer is slightly expanded. The activity\ncoefficients obtained within this model involve three characteristic lengths:\nDebye length, ion radius and quadrupolar length $L_Q$. Comparison to\nexperimental data shows that minimal distance between ions is equal to the sum\nof their bare ion radii; the concept for ion hydration as an obstacle for ions\nto come into contact is not needed for the understanding of the experimental\ndata."
    },
    {
        "anchor": "Dynamic Colloidal Stabilization by Nanoparticle Halos: We explore the conditions under which colloids can be stabilized by the\naddition of smaller particles. The largest repulsive barriers between colloids\noccur when the added particles repel each other with soft interactions, leading\nto an accumulation near the colloid surfaces. At lower densities these layers\nof mobile particles (nanoparticle halos) result in stabilization, but when too\nmany are added, the interactions become attractive again. We systematically\nstudy these effects --accumulation repulsion, re-entrant attraction, and\nbridging -- by accurate integral equation techniques.",
        "positive": "Interaction of Human Serum Albumin with short Polyelectrolytes: A study\n  by Calorimetry and Computer Simulation: We present a comprehensive study of the interaction of human serum albumin\n(HSA) with poly(acrylic acid) (PAA; number average degree of polymerization:\n25) in aqueous solution. The interaction of HSA with PAA is studied in dilute\nsolution as the function of the concentration of added salt (20 - 100 mM) and\ntemperature (25 - 37$^{\\circ}$C). Isothermal titration calorimetry (ITC) is\nused to analyze the interaction and to determine the binding constant and\nrelated thermodynamic data. It is found that only one PAA chain is bound per\nHSA molecule. The free energy of binding $\\Delta G_b$ increases with\ntemperature significantly. $\\Delta G_b$ decreases with increasing salt\nconcentration and is dominated by entropic contributions due to the release of\nbound counterions. Coarse-grained Langevin computer simulations treating the\ncounterions in an explicit manner are used study the process of binding in\ndetail. These simulations demonstrate that the PAA chains are bound in the\nSudlow II site of the HSA. Moreover, $\\Delta G_b$ is calculated from the\nsimulations and found to be in very good agreement with the measured data. The\nsimulations demonstrate clearly that the driving force of binding is the\nrelease of counterions in full agreement with the ITC-data."
    },
    {
        "anchor": "Persistent fluid flows defined by active matter boundaries: Biological systems achieve precise control over ambient fluids through the\nself-organization of active protein structures including flagella, cilia, and\ncytoskeletal networks. In active structures individual proteins consume\nchemical energy to generate force and motion at molecular length scales.\nSelf-organization of protein components enables the control and modulation of\nfluid flow fields on micron scales. The physical principles underlying the\norganization and control of active-matter driven fluid flows are poorly\nunderstood. Here, we apply an optically-controlled active-matter system\ncomposed of microtubule filaments and light-switchable kinesin motor proteins\nto analyze the emergence of persistent flow fields in a model active matter\nsystem. Using light, we form contractile microtubule networks of varying shape.\nWe analyze the fluid flow fields generated by a wide range of microtubule\nnetwork geometries and explain the resulting flow fields within a unified\ntheoretical framework. We specifically demonstrate that the geometry of\nmicrotubule flux at the boundary of contracting microtubule networks predicts\nthe steady-state fluid flow fields across polygonal network geometries through\nfinite-element simulations. Our work provides a foundation for programming\nmicroscopic fluid-flows with controllable active matter and could enable the\nengineering of versatile and dynamic microfluidic devices.",
        "positive": "Microstructures and Dynamics of Tetraalkylphosphonium Chloride Ionic\n  Liquids: Atomistic simulations have been performed to investigate the effect of\naliphatic chain length in tetraalkylphosphonium cations on liquid morphologies,\nmicroscopic ionic structures and dynamical properties of tetraalkylphosphonium\nchloride ionic liquids. The liquid morphologies are characterized by\nsponge-like interpenetrating polar and apolar networks in ionic liquids\nconsisting of tetraalkylphosphonium cations with short aliphatic chains. The\nlengthening aliphatic chains in tetraalkylphosphonium cations leads to polar\ndomains consisting of chloride anions and central polar groups in cations being\npartially or totally segregated in ionic liquid matrices due to a progressive\nexpansion of apolar domains in between. Prominent polarity alternation peaks\nand adjacency correlation peaks are observed at low and high $q$ range in total\nX-ray scattering structural functions, respectively, and their peak positions\ngradually shift to lower q values with lengthening aliphatic chains in\ntetraalkylphosphonium cations. The charge alternation peaks registered in\nintermediate q range exhibit complicated tendencies due to the complete\ncancellations of peaks and anti-peaks in partial structural functions for ionic\nsubcomponents. The particular microstructures and liquid morphologies in\ntetraalkylphosphonium chloride ionic liquids intrinsically contribute to\ndistinct dynamics characterized by translational diffusion coefficients, van\nHove correlation functions, and non-Gaussian parameters for ionic species in\nheterogeneous ionic environment. The increase of aliphatic chain length in\ntetraalkylphosphonium cations leads to concomitant shift of van Hove\ncorrelation functions and non-Gaussian parameters to larger radial distances\nand longer timescales, respectively, indicating the enhanced translational\ndynamical heterogeneities of tetraalkylphosphonium cations and the\ncorresponding chloride anions."
    },
    {
        "anchor": "Homogeneous Nucleation of Sheared Liquids: Advances and Insights from\n  Simulations and Theory: One of the most ubiquitous and technologically important phenomena in nature\nis the nucleation of homogeneous flowing systems. The microscopic effects of\nshear on a nucleating system are still imperfectly understood, although in\nrecent years a consistent picture has emerged. The opposing effects of shear\ncan be split into two major contributions for simple liquids: increase of the\nenergetic cost of nucleation, and enhancement of the kinetics. In this\nperspective, we describe the latest computational and theoretical techniques\nwhich have been developed over the past two decades. We collate and unify the\noverarching influences of shear, temperature, and supersaturation on the\nprocess of homogeneous nucleation. Experimental techniques and capabilities are\ndiscussed, against the backdrop of results from simulations and theory.\nAlthough we primarily focus on simple liquids, we also touch upon the sheared\nnucleation of more complex systems, including glasses and polymer melts. We\nspeculate on the promising directions and possible advances that could come to\nfruition in the future.",
        "positive": "Strain energy function for isotropic non-linear elastic incompressible\n  solids with linear finite strain response in shear and torsion: We find the strain energy function for isotropic incompressible solids\nexhibiting a linear relationship between shear stress and amount of shear, and\nbetween torque and amount of twist, when subject to large simple shear or\ntorsion deformations. It is inclusive of the well-known neo-Hookean and the\nMooney-Rivlin models, but also can accommodate other terms, as certain\narbitrary functions of the principal strain invariants. Effectively, the extra\nterms can be used to account for several non-linear effects observed\nexperimentally but not captured by the neo-Hookean and Mooney-Rivlin models,\nsuch as strain stiffening effects due to limiting chain extensibility."
    },
    {
        "anchor": "Nonreciprocal interactions give rise to fast cilium synchronisation in\n  finite systems: Motile cilia beat in an asymmetric fashion in order to propel the surrounding\nfluid. When many cilia are located on a surface, their beating can synchronise\nsuch that their phases form metachronal waves. Here, we computationally study a\nmodel where each cilium is represented as a spherical particle, moving along a\ntilted trajectory with a position-dependent active driving force and a\nposition-dependent internal drag coefficient. The model thus takes into account\nall the essential broken symmetries of the ciliary beat. We show that taking\ninto account the near-field hydrodynamic interactions, the effective coupling\nbetween cilia can become nonreciprocal: the phase of a cilium is more strongly\naffected by an adjacent cilium on one side than by a cilium at the same\ndistance in the opposite direction. As a result, synchronisation starts from a\nseed at the edge of a group of cilia and propagates rapidly across the system,\nleading to a synchronisation time that scales proportionally to the linear\ndimension of the system. We show that a ciliary carpet is characterised by\nthree different velocities: the velocity of fluid transport, the phase velocity\nof metachronal waves and the group velocity of order propagation. Unlike in\nsystems with reciprocal coupling, boundary effects are not detrimental for\nsynchronisation, but rather enable the formation of the initial seed.",
        "positive": "Phase separation in thermal systems: LB study and morphological\n  characterization: We investigate thermal and isothermal symmetric liquid-vapor separations via\na FFT-Thermal Lattice Boltzmann (FFT-TLB) model. Structure factor, domain size\nand Minkowski functionals are employed to characterize the density and velocity\nfields as well as to understand the configurations and the kinetic processes.\nCompared with the isothermal phase separation, the freedom in temperature\nprolongs the Spinodal Decomposition (SD) stage and induces different\nrheological and morphological behaviors in the thermal system. After the\ntransient procedure, both the thermal and isothermal separations show power-law\nscalings in domain growth; while the exponent for thermal system is lower than\nthat for isothermal system. With respect to the density of field, the\nisothermal system presents more likely bicontinuous configurations with\nnarrower interfaces, while the thermal system presents more likely\nconfigurations with scattered bubbles. Heat creation, conduction and lower\ninterfacial stresses are main reasons for the differences in thermal system.\nDifferent from the case with isothermal phase separation, the release of latent\nheat causes the changing of local temperature which results in new local\nmechanical balance. When the Prandtl number becomes smaller, the system\napproaches thermodynamical equilibrium more quickly. The increasing of mean\ntemperature makes lower the interfacial stress in the following way:\n$\\sigma=\\sigma_{0}[(T_{c}-T)/(T_{c}-T_{0})]^{3/2}$, where $T_{c}$ is the\ncritical temperature and $\\sigma_{0}$ is the interfacial stress at a reference\ntemperature $T_{0}$, which is the main reason for lower growth exponent in\nthermal case."
    },
    {
        "anchor": "Wall-Fluid and Liquid-Gas Interfaces of Model Colloid-Polymer Mixtures\n  by Simulation and Theory: We perform a study of the interfacial properties of a model suspension of\nhard sphere colloids with diameter $\\sigma_c$ and non-adsorbing ideal polymer\ncoils with diameter $\\sigma_p$. For the mixture in contact with a planar hard\nwall, we obtain from simulations the wall-fluid interfacial free energy,\n$\\gamma_{wf}$, for size ratios $q=\\sigma_p/\\sigma_c=0.6$ and 1, using\nthermodynamic integration, and study the (excess) adsorption of colloids,\n$\\Gamma_c$, and of polymers, $\\Gamma_p$, at the hard wall. The interfacial\ntension of the free liquid-gas interface, $\\gamma_{lg}$, is obtained following\nthree different routes in simulations: i) from studying the system size\ndependence of the interfacial width according to the predictions of capillary\nwave theory, ii) from the probability distribution of the colloid density at\ncoexistence in the grand canonical ensemble, and iii) for statepoints where the\ncolloidal liquid wets the wall completely, from Young's equation relating\n$\\gamma_{lg}$ to the difference of wall-liquid and wall-gas interfacial\ntensions, $\\gamma_{wl}-\\gamma_{wg}$. In addition, we calculate $\\gamma_{wf},\n\\Gamma_c$, and $\\Gamma_p$ using density functional theory and a scaled particle\ntheory based on free volume theory. Good agreement is found between the\nsimulation results and those from density functional theory, while the results\nfrom scaled particle theory quantitatively deviate but reproduce some essential\nfeatures. Simulation results for $\\gamma_{lg}$ obtained from the three\ndifferent routes are all in good agreement. Density functional theory predicts\n$\\gamma_{lg}$ with good accuracy for high polymer reservoir packing fractions,\nbut yields deviations from the simulation results close to the critical point.",
        "positive": "Influence of evaporation on soap film rupture: Although soap films are prone to evaporate due to their large surface to\nvolume ratio, the effect of evaporation on macroscopic film features has often\nbeen disregarded in the literature. In this work, we investigate experimentally\nthe influence of environmental humidity on soap film stability. An original\nexperiment allows to measure both the maximum length of a film pulled at\nconstant velocity and its thinning dynamics in a controlled atmosphere for\nvarious values of the relative humidity $\\RH$. At first order, the\nenvironmental humidity seems to have almost no impact on most of the film\nthinning dynamics. However, we find that the film length at rupture increases\ncontinuously with $\\RH$. To rationalize our observations, we propose that the\nfilm bursting occurs when the thinning due to evaporation becomes comparable to\nthe thinning due to liquid drainage. This rupture criterion turns out to be in\nreasonable agreement with an estimation of the evaporation rate in our\nexperiment."
    },
    {
        "anchor": "Reply to comment on ``Competing Interactions, the Renormalization Group\n  and the Isotropic-Nematic Phase Transition'': The focus of our work is to identify conditions for the presence of an\nisotropic-nematic phase transition in the context of a generic system with\nisotropic competing interactions. The comment 0709.4205 criticizes our results\nby showing that the low temperature fluctuations of a stripe phase in 2d\ndiverge linearly in the thermodynamic limit. The analysis is restricted to the\nstripe phase and does not apply to the central result of our letter. We show,\ncontrary to what is suggested in the comment, that the model introduced by D.\nG. Barci and D. A. Stariolo in PRL98, 200604 (2007) undergoes an\nisotropic-nematic phase transition in the Kosterlitz-Thouless universality\nclass.",
        "positive": "Fluctuating Nematodynamics using the Stochastic Method of Lines: We construct Langevin equations describing the fluctuations of the tensor\norder parameter $Q_{\\alpha\\beta}$ in nematic liquid crystals by adding noise\nterms to time-dependent variational equations that follow from the\nGinzburg-Landau-de Gennes free energy. The noise is required to preserve the\nsymmetry and tracelessness of the tensor order parameter and must satisfy a\nfluctuation-dissipation relation at thermal equilibrium. We construct a noise\nwith these properties in a basis of symmetric traceless matrices and show that\nthe Langevin equations can be solved numerically in this basis using a\nstochastic version of the method of lines. The numerical method is validated by\ncomparing equilibrium probability distributions, structure factors and dynamic\ncorrelations obtained from these numerical solutions with analytic predictions.\nWe demonstrate excellent agreement between numerics and theory. This\nmethodology can be applied to the study of phenomena where fluctuations in both\nthe magnitude and direction of nematic order are important, as for instance in\nthe nematic swarms which produce enhanced opalescence near the\nisotropic-nematic transition or the problem of nucleation of the nematic from\nthe isotropic phase."
    },
    {
        "anchor": "Active dynamics and spatially coherent motion in chromosomes subject to\n  enzymatic force dipoles: Inspired by recent experiments on chromosomal dynamics, we introduce an\nexactly solvable model for the interaction between a flexible polymer and a set\nof motor-like enzymes. The enzymes can bind and unbind to specific sites of the\npolymer and when bound produce a dipolar force on two neighboring monomers. We\nstudy the resulting non-equilibrium dynamics of the polymer and find that the\nmotion of the monomers has several properties that were observed experimentally\nfor chromosomal loci: a subdiffusive mean squared displacement and the\nappearance of regions of correlated motion. We also determine the velocity\nautocorrelation of the monomers and find that the underlying stochastic process\nis not fractional Brownian motion. Finally, we show that the active forces\nswell the polymer by an amount that becomes constant for large polymers.",
        "positive": "Size and interaction dependent solute diffusion in a dilute body\n  centered cubic solid solution: We report results of molecular dynamics simulations to understand the role of\nsolute and solute-solvent interaction on solute diffusivity in a solid solution\nwithin a body centered cubic solid when the solute size is significantly\nsmaller than the size of the solvent atom. Results show that diffusivity is\nmaximum for two specific sizes of the solute atom. This is the first time that\ntwin maxima have been found. The solute with diffusivity maxima are larger in\ncase of rigid host as compared to flexible host. This suggests that the effect\nof lattice vibrations is to decrease the size at which the maximum is seen. For\none of the $\\epsilon_{uv}$ where two diffusivity maxima have been observed, we\nhave analyzed various properties to understand the anomalous diffusion\nbehavior. It is characterized by a lower activation energy, lower\nbackscattering in the velocity autocorrelation function, lower mean square\nforce, single exponential decay of the intermediate scattering function and\nmonotonic dependence on $k$ of the $\\Delta \\omega/2Dk^2$ where $\\Delta \\omega$\nis the fwhm of the self part of the dynamic structure factor. Among the two\nsolute atoms at the anomalous maxima, the solute with higher diffusivity has\nlower activation energy."
    },
    {
        "anchor": "Electrostatic interactions across a charged lipid bilayer: We present theoretical work in which the degree of electrostatic coupling\nacross a charged lipid bilayer in aqueous solution is analyzed on the basis of\nnonlinear Poisson-Boltzmann theory. In particular, we consider the\nelectrostatic interaction of a single, large macroion with the two apposed\nleaflets of an oppositely charged lipid bilayer where the macroion is allowed\nto optimize its distance to the membrane. Three regimes are identified: a weak\nand a high macroion charge regime, separated by a regime of close\nmacroion-membrane contact for intermediate charge densities. The corresponding\nfree energies are used to estimate the degree of electrostatic coupling in a\nlamellar cationic lipid-DNA complex. That is, we calculate to what extent the\none-dimensional DNA arrays in a sandwich-like lipoplex interact across the\ncationic membranes. We find that, in spite of the low dielectric constant\ninside a lipid membranes, there can be a significant electrostatic contribution\nto the experimentally observed cross-bilayer orientational ordering of the DNA\narrays. Our approximate analytical model is complemented and supported by\nnumerical calculations of the electrostatic potentials and free energies of the\nlamellar lipoplex geometry. To this end, we solve the nonlinear\nPoisson-Boltzmann equation within a unit cell of the lamellar lipoplex using a\nnew lattice Boltzmann method.",
        "positive": "Understanding Brownian yet non-Gaussian diffusion via long-range\n  molecular interactions: In the last years, a few experiments in the fields of biological and soft\nmatter physics in colloidal suspensions have reported normal diffusion with a\nLaplacian probability distribution in the particles displacements (i.e.,\nBrownian yet non Gaussian diffusion). To model this behavior different\nstochastic models had been proposed, with all of them introducing new random\nelements that incorporate our lack of information about the media. Although\nthese models work in practice, due to their own nature a thorough understanding\nof how the media interacts with itself and with the Brownian particle in\nBrownian yet non Gaussian diffusion is outside of their aim and scope. For this\nreason, a comprehensive mathematical model to explain Brownian yet non Gaussian\ndiffusion that includes molecular interactions is proposed in this paper. Based\non the theory of interfaces by Gennes and Langevin dynamics, it is shown that\nlong-range interactions in a weakly interacting fluid and in a microscopic\nregime of zero viscosity leads to a Laplacian probability distribution in the\nparticles displacements. Further, it is shown that a phase transition can\nexplain a high diffusivity and causes this Laplacian distribution to evolve\ntowards a Gaussian via a transition probability in the interval of time as it\nwas observed in experiments. To validate these model predictions, the\nexperimental data of the Brownian motion of colloidal beads on phospholipid\nbilayer by Wang et al. is used and compared with the results of the theory.\nThis comparison suggests that the proposed model not only is able to explain\nqualitatively the Brownian yet non-Gaussian diffusion, but also quantitatively."
    },
    {
        "anchor": "Concerning the formation of chains of particles in the Kob-Andersen\n  (4:1) and Wahnstr{\u00f6}m (1:1) model liquids on coolind and supercooling: Investigations of structural changes happening with liquids on cooling and\nsupercooling continue to attract significant attention as there is still no\nsufficient understanding of the connection between the structural changes and\nthe dynamic slowdown. Previously, liquids' structures were usually discussed\nfrom the local perspective of individual particles. Here, we report on the\nstructural evolutions of the binary Kob-Andersen (KA) (4:1) and Wahnstr\\\"{o}m\n(1:1) model liquids using a different approach. The approach is based on the\npreviously not discussed observation that in the liquid and supercooled liquid\nstates some particles form nearly linear chains in the temperature region where\nthe crystallization process has not been observed. Depending on the chain\ndefinition, it is possible to speak about the chains containing more than 8\nparticles. The average number of chains monotonically increases as the\ntemperature of the liquid decreases. Considerations of the inherent structures\nshow that the number of chains remains nearly constant in the inherent\nstructures (IS) obtained from the parent structures (PS) above the potential\nenergy landscape (PEL) crossover temperature (PELCT). Below the PELCT, the\naverage number of chains in the IS increases, as the temperature of the PS\ndecreases. Counter-intuitively, for the KA system, below the PELCT the number\nof chains in the PS can be larger than the number of chains in the\ncorresponding IS. The distributions of the potential energies (PE) of the\nparticles in chains show that the particles forming the chains tend to have\nhigher PE than the particles which are not in the chains. We also found that\nthe particles forming the chains diffuse at a slightly lower rate than the\nglobal average. We also discuss the lifetimes of the chains. We compare some of\nour results with the results obtained within the topological cluster\nclassification approach.",
        "positive": "Flexoelectric blue phases: We describe the occurence and properties of liquid crystal phases showing two\ndimensional splay and bend distortions which are stabilised by flexoelectric\ninteractions. These phases are characterised by regions of locally double\nsplayed order separated by topological defects and are thus highly analogous to\nthe blue phases of cholesteric liquid crystals. We present a mean field\nanalysis based upon the Landau--de Gennes Q-tensor theory and construct a phase\ndiagram for flexoelectric structures using analytic and numerical results. We\nstress the similarities and discrepancies between the cholesteric and\nflexoelectric cases."
    },
    {
        "anchor": "A model for gelation with explicit solvent effects: Structure and\n  dynamics: We study a two-component model for gelation consisting of $f$-functional\nmonomers (the gel) and inert particles (the solvent). After equilibration as a\nsimple liquid, the gel particles are gradually crosslinked to each other until\nthe desired number of crosslinks has been attained. At a critical crosslink\ndensity the largest gel cluster percolates and an amorphous solid forms. This\npercolation process is different from ordinary lattice or continuum percolation\nof a single species in the sense that the critical exponents are new. As the\ncrosslink density $p$ approaches its critical value $p_c$, the shear viscosity\ndiverges: $\\eta(p)\\sim (p_c-p)^{-s}$ with $s$ a nonuniversal\nconcentration-dependent exponent.",
        "positive": "Temperature dependence of the static permittivity andintegral formula\n  for the Kirkwood correlation factor ofsimple polar fluids: An exact integral formula for the Kirkwood correlation factor of isotropic\npolar fluids $g_K$ is derived from the equilibrium averaged rotational Dean\nequation, which as compared to previous approaches easily lends itself to\nfurther approximations. The static linear permittivity of polar fluids\n$\\epsilon$ is calculated as a function of temperature, density and molecular\ndipole moment in vacuo for arbitrary pair interaction potentials. Then, using\nthe Kirkwood superposition approximation for the three-body orientational\ndistribution function, we suggest a simple way to construct model potentials of\nmean torques considering permanent and induced dipole moments. We successfully\ncompare the theory with the experimental temperature dependence of the static\nlinear permittivity of various polar fluids such as a series of linear\nmonohydroxy alcohols, water, tributyl phosphate, acetonitrile, acetone,\nnitrobenzene and dimethyl sulfoxide, by fitting only one single parameter,\nwhich describes the induction to dipole-dipole energy strength ratio. We\ndemonstrate that comparing the value of $g_K$ with unity in order to deduce the\nalignment state of permanent dipole pairs, as is currently done is in many\nsituations, is a misleading oversimplification, while the correct alignment\nstate is revealed when considering the proper interaction potential. Moreover\nwe show, that picturing H-bonding polar fluids as polar molecules with\npermanent and induced dipole moments without invoking any specific H-bonding\nmechanism is in many cases sufficient to explain experimental data of the\nstatic dielectric constant. In this light, the failure of the theory to\ndescribe the experimental temperature dependence of the static dielectric\nconstant of glycerol, a non-rigid polyalcohol, is not due to the lack of\nspecific H-bonding mechanisms, but rather to an oversimplified model potential\nfor that particular molecule."
    },
    {
        "anchor": "Coalescence driven self-organization of growing nanodroplets around a\n  microcap: The coalescence between growing droplets is important for the surface\ncoverage and spatial arrangements of droplets on surfaces. In this work, total\ninternal reflection fluorescence (TIRF) microscopy is utilized to in-situ\ninvestigate the formation of nanodroplets around the rim of a polymer microcap,\nwith sub-micron spatial and millisecond temporal resolution. We observe that\nthe coalescence among droplets occurs frequently during their growth by solvent\nexchange. Our experimental results show that the position of the droplet from\ntwo merged droplets is related to the size of the parent droplets. The position\nof the coalesced droplet and the ratio of parent droplet sizes obey a scaling\nlaw, reflecting a coalescence preference based on the size inequality. As a\nresult of droplet coalescence, the angles between the centroids of two\nneighbouring droplets increase with time, obeying a nearly symmetrical\narrangement of droplets at various time intervals. The evolution of the\nposition and number from coalescence of growing droplets is modelled. The\nmechanism for coalescence driven self-organization of growing droplets is\ngeneral, applicable to microcaps of different sizes and droplets of different\nliquids. The understanding from this work may be valuable for positioning\nnanodroplets by nucleation and growth without using templates.",
        "positive": "Remark on the Entropy Production of Adaptive Run-and-Tumble Chemotaxis: Chemotactic active particles, such as bacteria and cells, exhibit an adaptive\nrun-and-tumble motion, giving rise to complex emergent behaviors in response to\nexternal chemical fields. This motion is generated by the conversion of\ninternal chemical energy into self-propulsion, allowing each agent to sustain a\nsteady-state far from thermal equilibrium and perform works. The rate of\nentropy production serves as an indicates of how extensive these agents operate\naway from thermal equilibrium, providing a measure for estimating maximum\nobtainable power. Here we present the general framework for calculating the\nentropy production rate created by such population of agents from the first\nprinciple, using the minimal model of bacterial adaptive chemotaxis, as they\nexecute the most basic collective action -- the mass transport."
    },
    {
        "anchor": "Stochastic dynamics of dissolving active particles: The design of artificial microswimmers has generated significant research\ninterest in recent years, for promise in applications such as nanomotors and\ntargeted drug-delivery. However, many current designs suffer from a common\nproblem, namely the swimmers remain in the fluid indefinitely, posing risks of\nclogging and damage. Inspired by recently proposed experimental designs, we\ninvestigate mathematically the dynamics of degradable active particles. We\ndevelop and compare two distinct chemical models for the decay of a swimmer,\ntaking into account the material composition and nature of the chemical or\nenzymatic reaction at its surface. These include a model for dissolution\nwithout a reaction, as well as models for a reacting swimmer studied in the\nlimit of large and small Damk\\\"ohler number. A new dimensionless parameter\nemerges that allows the classification of colloids into ballistic and diffusive\ntype. Using this parameter, we perform an asymptotic analysis to derive\nexpressions for colloid lifetimes and their total mean-squared displacement\nfrom release and validate these by numerical Monte Carlo simulations of the\nassociated Langevin dynamics. Supported by general scaling relationships, our\ntheoretical results provide new insight into the experimental applicability of\na wide range of designs for degradable active colloids.",
        "positive": "Vortex phase diagram in trapped Bose-Einstein condensation: The vortex phase diagram in the external rotation frequency versus\ntemperature is calculated for dilute Bose-Einstein condensed gases. It is\ndetermined within the Bogoliubov-Popov theory for a finite temperature where\nthe condensate and non-condensate fractions are treated in an equal footing.\nThe temperature dependences of various thermodynamic instability lines for the\nvortex nucleation are computed to construct the phase diagram. Experiments are\nproposed to resolve a recent controversy on the vortex creation problem\nassociated with the quantized vortex observation in $^{87}$Rb atom gases."
    },
    {
        "anchor": "The Power of Poincar\u00e9: Elucidating the Hidden Symmetries in Focal\n  Conic Domains: Focal conic domains are typically the \"smoking gun\" by which smectic liquid\ncrystalline phases are identified. The geometry of the equally-spaced smectic\nlayers is highly generic but, at the same time, difficult to work with. In this\nLetter we develop an approach to the study of focal sets in smectics which\nexploits a hidden Poincar\\'e symmetry revealed only by viewing the smectic\nlayers as projections from one-higher dimension. We use this perspective to\nshed light upon several classic focal conic textures, including the concentric\ncyclides of Dupin, polygonal textures and tilt-grain boundaries.",
        "positive": "Shear-Induced Stress Relaxation in a Two-Dimensional Wet Foam: We report on experimental measurements of the flow behavior of a wet,\ntwo-dimensional foam under conditions of slow, steady shear. The initial\nresponse of the foam is elastic. Above the yield strain, the foam begins to\nflow. The flow consists of irregular intervals of elastic stretch followed by\nsudden reductions of the stress, i.e. stress drops. We report on the\ndistribution of the stress drops as a function of the applied shear rate. We\nalso comment on our results in the context of various two-dimensional models of\nfoams."
    },
    {
        "anchor": "Polyelectrolytes in electric fields: Measuring the dynamical effective\n  charge and effective friction: We use a coarse-grained molecular dynamics model to study the electrophoretic\nbehaviour of flexible polyelectrolyte chains. We first characterize the static\nproperties of the model with respect to the chain length, the polyelectrolyte\nconcentration, additional salt and the influence of an applied external field.\nNext we investigate the dynamic behaviour in the oligomer range and compare to\ndata obtained by two different experimental methods, namely capillary\nelectrophoresis and PFG-NMR. We find excellent agreement of experiments and\nsimulations when hydrodynamic interactions are accounted for in the\nsimulations. We then present novel estimators for the dynamical effective\ncharge during free solution electrophoresis and compare them to static\nestimators. We find complete agreement between the static and the dynamic\nestimators. We further evaluate the scaling behaviour of the effective friction\nof the polyelectrolyte-counterion complex with the surrounding fluid. We\nidentify a hydrodynamic screening length beyond which the friction during\nelectrophoresis is linear depending on the chain length resulting in a constant\nmobility for long polyelectrolyte chains. Our results show a convincing\nagreement with experimental data and demonstrate that it is possible to model\ndynamic behaviour of polyelectrolytes using coarse grained models, provided\nthey include the effects of hydrodynamical interactions.",
        "positive": "Fractal generation in a two-dimensional active-nematic fluid: Active fluids, composed of individual self-propelled agents, can generate\ncomplex large-scale coherent flows. A particularly important laboratory\nrealization of such an active fluid is a system composed of microtubules,\naligned in a quasi-two-dimensional (2D) nematic phase, and driven by ATP-fueled\nkinesin motor proteins. This system exhibits robust chaotic advection and gives\nrise to a pronounced fractal structure in the nematic contours. We characterize\nsuch experimentally derived fractals using the power spectrum and discover that\nthe power spectrum decays as $k^{-\\beta}$ for large wavenumbers $k$. The\nparameter $\\beta$ is measured for several experimental realizations. Though\n$\\beta$ is effectively constant in time, it does vary with experimental\nparameters, indicating differences in the scale-free behavior of the\nmicrotubule-based active nematic. Though the fractal patterns generated in this\nactive system are reminiscent of passively advected dye in 2D chaotic flows,\nthe underlying mechanism for fractal generation is more subtle. We provide a\nsimple, physically inspired mathematical model of fractal generation in this\nsystem that relies on the material being locally compressible, though the total\narea of the material is conserved globally. The model also requires that\nlarge-scale density variations be injected into the material periodically. The\nmodel reproduces the power spectrum decay $k^{-\\beta}$ seen in experiments.\nLinearizing the model of fractal generation about the equilibrium density, we\nderive an analytic relationship between $\\beta$ and a single dimensionless\nquantity $r$, which characterizes the compressibility."
    },
    {
        "anchor": "Dressed Counterions: Poly- and monovalent ions at charged dielectric\n  interfaces: We investigate the ion distribution and overcharging at charged interfaces\nwith dielectric inhomogeneities in the presence of asymmetric electrolytes\ncontaining polyvalent and monovalent ions. We formulate an effective \"dressed\ncounterion\" approach by integrating out the monovalent salt degrees of freedom\nand show that it agrees with results of explicit Monte-Carlo simulations. We\nthen apply the dressed counterion approach within the framework of the\nstrong-coupling theory, valid for polyvalent ions at low concentrations, which\nenables an analytical description for salt effects as well as dielectric\ninhomogeneities in the limit of strong Coulomb interactions on a systematic\nlevel. Limitations and applicability of this theory are examined by comparing\nthe results with simulations.",
        "positive": "Rheology of an inverted cholesteric droplet under shear flow: The dynamics of a quasi two-dimensional isotropic droplet in a cholesteric\nliquid crystal medium under symmetric shear flow is studied by lattice\nBoltzmann simulations. We consider a geometry in which the flow direction is\nalong the axis of the cholesteric, as this setup exhibits a significant\nviscoelastic response to external stress. We find that the dynamics depends\nupon the magnitude of the shear rate, the anchoring strength of the liquid\ncrystal at the droplet interface and the chirality. While for low shear rate\nand weak interface anchoring the system shows a non-Newtonian behavior, a\nNewtonian-like response is observed at high shear rate and strong interface\nanchoring. This is investigated both by estimating the secondary flow profile,\nnamely a flow emerging along the out-of-plane direction (absent in fully\nNewtonian fluids, such as water), and by monitoring defect formation and\ndynamics which alter significantly the rheological response of the system."
    },
    {
        "anchor": "Strong screening in the plum pudding model: We study a generalized Thomson problem that appears in several condensed\nmatter settings: identical point-charge particles can penetrate inside a\nhomogeneously charged sphere, with global electro-neutrality. The emphasis is\non scaling laws at large Coulombic couplings, and deviations from mean-field\nbehaviour, by a combination of Monte Carlo simulations and an analytical\ntreatment within a quasi-localized charge approximation, which provides\nreliable predictions. We also uncover a local overcharging phenomenon driven by\nionic correlations alone.",
        "positive": "Hierarchies of networked phases induced by multiple liquid-liquid\n  critical points: Functionalization of nanoparticles or colloids is increasingly being used to\ndevelop customizable \"atoms\". Functionalization by attaching single strands of\nDNA allows for direct control of the binding between nanoparticles, since\nhybridization of double strands will only occur if the base sequences of single\nstrands are complementary. Nanoparticles and colloids functionalized by four\nsingle strands of DNA can be thought of as designed analogs to tetrahedral\nnetwork forming atoms and molecules, with a difference that the attached DNA\nstrands allow for control of the length scale of bonding relative to the core\nsize. We explore the behavior of an experimentally realized model for a\nnanoparticles functionalized by four single strands of DNA (a tetramer), and\nshow that this single-component model exhibits a rich phase diagram with at\nleast three critical points and four thermodynamically distinct amorphous\nphases. We demonstrate that the additional critical points are part of the\nIsing universality class, like the ordinary liquid-gas critical point. The\ndense phases consist of a hierarchy of interpenetrating networks, reminiscent\nof a woven cloth. Thus bonding specificity of DNA provides an effective route\nto generate new nano-networked materials with polyamorphic behavior. The\nconcept of network interpenetration helps to explain the generation of multiple\nliquid phases in single-component systems, suggested to occur in some atomic\nand molecular network forming fluids, including water and silica."
    },
    {
        "anchor": "How liquid-liquid phase separation induces active spreading: The interplay between phase separation and wetting of multicomponent mixtures\nis ubiquitous in nature and technology and recently gained significant\nattention across scientific disciplines, due to the discovery of biomolecular\ncondensates. It is well understood that sessile droplets, undergoing phase\nseparation in a static wetting configuration, exhibit microdroplet nucleation\nat their contact lines, forming an oil ring during later stages. However, very\nlittle is known about the dynamic counterpart, when phase separation occurs in\na non-equilibrium wetting configuration, i.e., spreading droplets. Here we\nreport that liquid-liquid phase separation strongly couples to the spreading\nmotion of three-phase contact lines. Thus, the classical Cox-Voinov law is not\napplicable anymore, because phase separation adds an active spreading force\nbeyond the capillary driving. Intriguingly, we observe that spreading starts\nwell before any visible nucleation of microdroplets in the main droplet. Using\nhigh-speed ellipsometry, we further demonstrate that surface forces cause an\neven earlier nucleation in the wetting precursor film around the droplet,\ninitiating the observed wetting transition. We expect our findings to enrich\nthe fundamental understanding of phase separation processes that involve\ndynamical contact lines and/or surface forces, with implications in a wide\nrange of applications, from oil recovery or inkjet printing to material\nsynthesis and biomolecular condensates.",
        "positive": "Distance dependence of angular correlations in dense polymer solutions: Angular correlations in dense solutions and melts of flexible polymer chains\nare investigated with respect to the distance $r$ between the bonds by\ncomparing quantitative predictions of perturbation calculations with numerical\ndata obtained by Monte Carlo simulation of the bond-fluctuation model. We\nconsider both monodisperse systems and grand-canonical (Flory-distributed)\nequilibrium polymers. Density effects are discussed as well as finite chain\nlength corrections. The intrachain bond-bond correlation function $P(r)$ is\nshown to decay as $P(r) \\sim 1/r^3$ for $\\xi \\ll r \\ll \\r^*$ with $\\xi$ being\nthe screening length of the density fluctuations and $r^* \\sim N^{1/3}$ a novel\nlength scale increasing slowly with (mean) chain length $N$."
    },
    {
        "anchor": "Dynamics of Polymer Decompression: Expansion, Unfolding and Ejection: The dynamics of polymer decompression, i.e., a process from compressed,\ncompact state to the relaxed swoll en conformation, can be formally described\nas a {\\it nonlinear diffusion}. We discuss here two basic examples: (i) the\nexpansion, or unfolding from a compact state, and (ii) the ejection of pressed\npolymer through a pore. The problem can be solved exactly for the case (i), but\nnot for the latter. Even in such situations, a scheme called {\\it uniform\napproximation} is shown to be useful to get a physical insight involved. Its\napplication to the case (ii) is able to account for conflicting numerical data\nin a consistent way.",
        "positive": "Onset of Non-Linearity in the Elastic Bending of Blocks: The classical flexure problem of non-linear incompressible elasticity is\nrevisited assuming that the bending angle suffered by the block is specified\ninstead of the usual applied moment. The general moment-bending angle\nrelationship is then obtained and is shown to be dependent on only one\nnon-dimensional parameter: the product of the aspect ratio of the block and the\nbending angle. A Maclaurin series expansion in this parameter is then found.\nThe first-order term is proportional to $\\mu$, the shear modulus of linear\nelasticity; the second-order term is identically zero, because the moment is an\nodd function of the angle; and the third-order term is proportional to\n$\\mu(4\\beta -1)$, where $\\beta$ is the non-linear shear coefficient, involving\nthird-order and fourth-order elasticity constants. It follows that bending\nexperiments provide an alternative way of estimating this coefficient, and the\nresults of one such experiment are presented. In passing, the coefficients of\nRivlin's expansion in exact non-linear elasticity are connected to those of\nLandau in weakly (fourth-order) non-linear elasticity."
    },
    {
        "anchor": "Controlling electrostatic co-assembly using ion-containing copolymers :\n  from surfactants to nanoparticles: In this review, we address the issue of the electrostatic complexation\nbetween charged-neutral diblock copolymers and oppositely charged nanocolloids.\nWe show that nanocolloids such as surfactant micelles and iron oxide magnetic\nnanoparticles share similar properties when mixed with charged-neutral\ndiblocks. Above a critical charge ratio, core-shell hierarchical structures\nform spontaneously under direct mixing conditions. The core-shell structures\nare identified by a combination of small-angle scattering techniques and\ntransmission electron microscopy. The formation of multi-level objects is\ndriven by the electrostatic attraction between opposite charges and by the\nrelease of the condensed counterions. Alternative mixing processes inspired\nfrom molecular biology are also described. The protocols applied here consist\nin screening the electrostatic interactions of the mixed dispersions, and then\nremoving the salt progressively as example by dialysis. With these techniques,\nthe oppositely charged species are intimately mixed before they can interact,\nand their association is monitored by the desalting kinetics. As a result,\nsphere- and rod-like aggregates with remarkable superparamagnetic and stability\nproperties are obtained. These findings are discussed in the light of a new\nparadigm which deals with the possibility to use inorganic nanoparticles as\nbuilding blocks for the design and fabrication of supracolloidal assemblies\nwith enhanced functionalities.",
        "positive": "vdW-DF Study of energetic, structural, and vibrational properties of\n  small water clusters and ice Ih: We present results for a density functional theory study of small water\nclusters and hexagonal ice Ih, using the van der Waals density functional\n(vdW-DF). In particular, we examine energetic, structural, and vibrational\nproperties of these systems. Our results exhibit excellent agreement with both\nexperiment and quantum-chemistry calculations and show a systematic and\nconsistent improvement over standard exchange-correlation functionals---making\nvdW-DF a promising candidate for resolving longstanding difficulties with\ndensity functional theory in describing water. In addition, by comparing our\nvdW-DF results with quantum-chemistry calculations and other standard\nexchange-correlation functionals, we shed light on the question of why standard\nfunctionals often fail to describe these systems accurately."
    },
    {
        "anchor": "On the computational modeling of the viscosity of colloidal dispersions\n  and its relation with basic molecular interactions: The connection between fundamental interactions acting in molecules in a\nfluid and macroscopically measured properties, such as the viscosity between\ncolloidal particles coated with polymers, is studied here. The role that\nhydrodynamic and Brownian forces play in colloidal dispersions is also\ndiscussed. It is argued that many body systems in which all these interactions\ntake place can be accurately solved using computational simulation tools. One\nof those modern tools is the technique known as dissipative particle dynamics,\nwhich incorporates Brownian and hydrodynamic forces, as well as basic\nconservative interactions. A case study is reported, as an example of the\napplications of this technique, which consists of the prediction of the\nviscosity and friction between two opposing parallel surfaces covered with\npolymer chains, under the influence of a steady flow. This work is intended to\nserve as an introduction to the subject of colloidal dispersions and computer\nsimulations, for last year undergraduate students and beginning graduate\nstudents who are interested in beginning research in soft matter systems. To\nthat end, a computational code is included that students can use right away to\nstudy complex fluids in equilibrium.",
        "positive": "Semiflexible Polymer Confined in Closed Spaces: We analyze static properties of a strongly confined semiflexible polymer,\ni.e. either trapped in a closed space or compressed by external forces, in an\nathermal solvent. Like a flexible polymer case, we can resort to an analogy\nwith the semidilute solution, but a complication due to the additional length\nscale arising from the chain rigidity results in more diverse behaviours\ndepending on system parameters. For each regime, scaling forms of the excess\nfree energy of the confinement are derived. Effects of the confinement geometry\nand the solvent quality are briefly discussed."
    },
    {
        "anchor": "A pedagogical introduction to the replica method for fragile glasses: In this note I present a simplified version of the recent computation (Mezard\nand Parisi 1998, 1999) of the properties of glasses in the low temperature\nphase in the framework of the replica theory, using an extension of the tools\nused in liquid theory. I will only consider here the case of the internal\nenergy at T=0, which can be studied in a simple way without introducing\nreplicas.",
        "positive": "Nonergodic Subdiffusion from Brownian Motion in an Inhomogeneous Medium: Nonergodicity observed in single-particle tracking experiments is usually\nmodeled by transient trapping rather than spatial disorder. We introduce models\nof a particle diffusing in a medium consisting of regions with random sizes and\nrandom diffusivities. The particle is never trapped, but rather performs\ncontinuous Brownian motion with the local diffusion constant. Under simple\nassumptions on the distribution of the sizes and diffusivities, we find that\nthe mean squared displacement displays subdiffusion due to non-ergodicity for\nboth annealed and quenched disorder. The model is formulated as a walk\ncontinuous in both time and space, similar to the L\\'{e}vy walk."
    },
    {
        "anchor": "A mode-coupling theory for the pasty rheology of soft glassy materials: In this paper, we introduce a simple mode-coupling model for concentrated\nsuspensions under flow . This model exhibits a jamming transition, and stress\nvs shear rate relations which are very similar to experimental results. Namely\nnewtonian regime or yield stress are followed by a slow variation of the stress\nfor higher shear rates, and by an apparent newtonian regime for very large\nshear rates. Another striking result is that under oscillating strain, even in\nthe jammed state, the system exhibits a relaxation time which depends on the\nstrain amplitude.",
        "positive": "A stability-reversibility map unifies elasticity, plasticity, yielding\n  and jamming in hard sphere glasses: Amorphous solids, such as glasses, have complex responses to deformations,\nwith significant consequences in material design and applications. In this\nrespect two intertwined aspects are important: stability and reversibility. It\nis crucial to understand on the one hand how a glass may become unstable due to\nincreased plasticity under shear deformations; on the other hand, to what\nextent the response is reversible, meaning how much a system is able to recover\nthe original configuration once the perturbation is released. Here we focus on\nassemblies of hard spheres as the simplest model of amorphous solids such as\ncolloidal glasses and granular matter. We prepare glass states quenched from\nequilibrium supercooled liquid states, which are obtained by using the swap\nMonte Carlo algorithm and correspond to a wide range of structural relaxation\ntime scales. We exhaustively map out their stability and reversibility under\nvolume and shear strains, using extensive numerical simulations. The region on\nthe volume-shear strain phase diagram where the original glass state remains\nsolid is bounded by the shear-yielding and the shear-jamming lines which meet\nat a yielding-jamming crossover point. This solid phase can be further divided\ninto two sub-phases: the stable glass phase where the system deforms purely\nelastically and is totally reversible, and the marginal glass phase where it\nexperiences stochastic plastic deformations at mesoscopic scales and is\npartially irreversible. The details of the stability-reversibility map depend\nstrongly on the quality of annealing of the glass. This study provides a\nunified framework for understanding elasticity, plasticity, yielding and\njamming in amorphous solids."
    },
    {
        "anchor": "Hydrodynamic induced deformation and orientation of a microscopic\n  elastic filament: We describe simulations of a microscopic elastic filament immersed in a fluid\nand subject to a uniform external force. Our method accounts for the\nhydrodynamic coupling between the flow generated by the filament and the\nfriction force it experiences. While models that neglect this coupling predict\na drift in a straight configuration, our findings are very different. Notably,\na force with a component perpendicular to the filament axis induces bending and\nperpendicular alignment. Moreover, with increasing force we observe four shape\nregimes, ranging from slight distortion to a state of tumbling motion that\nlacks a steady state. We also identify the appearance of marginally stable\nstructures. Both the instability of these shapes and the observed alignment can\nbe explained by the combined action of induced bending and non-local\nhydrodynamic interactions. Most of these effects should be experimentally\nrelevant for stiff micro-filaments, such as microtubules.",
        "positive": "Ferroelectric nematic liquid crystalline phases: Recent experimental realization of ferroelectric nematic liquid crystalline\nphases stimulated material development and numerous experimental studies of\nthese new phases, guided by their fundamental and applicative interest. In this\nPerspective, we give an overview of this emerging field by linking history and\ntheoretical predictions to a general outlook of the development and properties\nof the materials exhibiting ferroelectric nematic phases. We will highlight the\nmost relevant observations up-to-date, e.g., giant dielectric permittivity\nvalues, polarization values an order of magnitude larger than in classical\nferroelectric liquid crystals, and nonlinear optical coefficients comparable to\nseveral ferroelectric solid materials. Key observations of anchoring and\nelectro-optic behavior will also be examined. The collected contributions lead\nto a final discussion on open challenges in materials development, theoretical\ndescription, experimental explorations, and possible applications of the\nferroelectric phases."
    },
    {
        "anchor": "Comparison of Dynamical Heterogeneity in Hard-Sphere and Attractive\n  Glass Formers: Using molecular dynamics simulations, we have determined that the nature of\ndynamical heterogeneity in jammed liquids is very sensitive to short-ranged\nattractions. Weakly attractive systems differ little from dense hard-sphere and\nLennard-Jones fluids: Particle motion is punctuated and tends to proceed in\nsteps of roughly a single particle diameter. Both of these basic features\nchange in the presence of appreciable attractions. Transient periods of\nparticle mobility and immobility cannot be discerned at intermediate attraction\nstrength, for which structural relaxation is greatly enhanced. Strong\nattractions, known to dramatically inhibit relaxation, restore bimodality of\nparticle motion. But in this regime, transiently mobile particles move in steps\nthat are significantly more biased toward large displacements than in the case\nof weak attractions. This modified feature of dynamic heterogeneity, which\ncannot be captured by conventional mode coupling theory, verifies recent\npredictions from a model of spatially correlated facilitating defects.",
        "positive": "Effects of linker flexibility on phase behavior and structure of linked\n  colloidal gels: Colloidal nanocrystal gels can be assembled using a difunctional \"linker\"\nmolecule to mediate bonding between nanocrystals. The conditions for gelation\nand the structure of the gel are controlled macroscopically by the linker\nconcentration and microscopically by the linker's molecular characteristics.\nHere, we demonstrate using a toy model for a colloid-linker mixture that linker\nflexibility plays a key role in determining both phase behavior and structure\nof the mixture. We fix the linker length and systematically vary its bending\nstiffness to span the flexible, semiflexible, and rigid regimes. At fixed\nlinker concentration, flexible-linker and rigid-linker mixtures phase separate\nat low colloid volume fractions in agreement with predictions of first-order\nthermodynamic perturbation theory, but the semiflexible-linker mixtures do not.\nWe correlate and attribute this qualitatively different behavior to undesirable\n\"loop\" linking motifs that are predicted to be more prevalent for linkers with\nend-to-end distances commensurate with the locations of chemical bonding sites\non the colloids. Linker flexibility also influences the spacing between linked\ncolloids, suggesting strategies to design gels with desired phase behavior,\nstructure, and by extension, structure-dependent properties."
    },
    {
        "anchor": "Influence of humidity on the tribo-electric charging and segregation in\n  shaken granular media: We study the effect of humidity on the charge accumulation of polymer\ngranulates shaken vertically in a stainless steel container. The setup allows\nto control the humidity level from 5 % to 100 %RH while performing automated\ncharge measurements in a Faraday cup directly connected to the shaking\ncontainer. We find that samples of approximately 2000 polymer spheres become\nhighly charged at low humidity levels (<30 %RH), but acquire almost no charge\nfor humidity levels above 80 %RH. The transition between these two regimes does\ndepend on the material, as does the sign of the charge. For the latter we find\na correlation with the contact angle of the polymer with only very hydrophilic\nparticles attaining positive charges. We show that this humidity dependence of\ntribo-charging can be used to control segregation in shaken binary mixtures.",
        "positive": "Theoretical Perspectives on Protein Folding: Understanding how monomeric proteins fold under in vitro conditions is\ncrucial to describing their functions in the cellular context. Significant\nadvances both in theory and experiments have resulted in a conceptual framework\nfor describing the folding mechanisms of globular proteins. The experimental\ndata and theoretical methods have revealed the multifaceted character of\nproteins. Proteins exhibit universal features that can be determined using only\nthe number of amino acid residues (N) and polymer concepts. The sizes of\nproteins in the denatured and folded states, cooperativity of the folding\ntransition, dispersions in the melting temperatures at the residue level, and\ntime scales of folding are to a large extent determined by N. The consequences\nof finite N especially on how individual residues order upon folding depends on\nthe topology of the folded states. Such intricate details can be predicted\nusing the Molecular Transfer Model that combines simulations with measured\ntransfer free energies of protein building blocks from water to the desired\nconcentration of the denaturant. By watching one molecule fold at a time, using\nsingle molecule methods, the validity of the theoretically anticipated\nheterogeneity in the folding routes, and the N-dependent time scales for the\nthree stages in the approach to the native state have been established. Despite\nthe successes of theory, of which only a few examples are documented here, we\nconclude that much remains to be done to solve the \"protein folding problem\" in\nthe broadest sense."
    },
    {
        "anchor": "Altered Dielectric Behaviour, Structure and Dynamics of Nanoconfined\n  Dipolar Liquids: Signatures of Enhanced Cooperativity: Spherical confinement can alter the properties of a dipolar fluid in several\ndifferent ways. In an atomistic molecular dynamics simulation study of two\ndifferent dipolar liquids (SPC/E water and a model Stockmayer fluid) confined\nto nanocavities of different radii ranging from Rc=1nm to 4nm, we find that the\nKirkwood correlation factor remains surprisingly small in water, but not so in\nmodel Stockmayer liquid. This gives rise to an anomalous ultrafast relaxation\nof the total dipole moment time correlation function (DMTCF). The static\ndielectric constant of water under nanoconfinement (computed by employing\nClausius-Mossotti equation, the only exact relation) exhibits a strong\ndependence on the size of the nanocavity with a remarkably slow convergence to\nthe bulk value. Interestingly, the value of the volume becomes ambiguous in\nthis nanoworld. It is determined by the liquid-surface interaction potential\nand is to be treated with care because of the sensitivity of the\nClausius-Mossotti equation to the volume of the nanosphere. We discover that\nthe DMTCF for confined water exhibit a bimodal 1/f noise power spectrum. We\nalso comment on the applicability of certain theoretical formalisms that become\ndubious in the nanoworld.",
        "positive": "Stall, spiculate or runaway - the fate of fibers growing towards\n  fluctuating membranes: We solve the dynamic equations of motion for a growing semi-flexible polymer,\nor fiber, approaching a fluctuating membrane at an angle. At late times we find\nthree different regimes: fiber {\\em stalling}, when fiber growth stops due to\nmembrane resistence, {\\em run-away}, in which the polymer bends away from the\nmembrane, and another regime in which the membrane response is nonlinear and\ntubular membrane {\\em spicules} are formed. We discuss which regions of the\nresulting `phase diagram' are explored by (i) single and bundled actin fibers\nin living cells, (ii) sickle hemoglobin fibers in red blood cells, and (iii)\nmicrotubules growing within artificial vesicles. We complement our analysis\nwith full 3-dimensional stochastic simulations."
    },
    {
        "anchor": "Effective medium model for a suspension of active swimmers: Several active organisms in nature tend to reside as a community in a viscous\nfluid medium. We analyze the variation of swimming characteristics of an active\nswimmer present in a dilute and disperse suspension, modeled as an effective\nBrinkman medium. This idealized representation of a collection of active\nswimmers allows one to distinguish the impact of the interior domain available\nto an individual swimmer as well as the contribution of its neighbors. Darcy's\nlaw along with the analytical solution enables the effective resistivity to be\npredicted as a function of the volume fraction which is in close agreement with\nthe well-known Carman-Kozeny equation. This facilitates the successive analysis\nof the propulsion speed, power dissipation, and swimming efficiency of the\ntargeted swimmer as a function of the volume fraction which is decisive in\nnutrient transport and uptake or reproduction in a collective environment. A\nstress-jump condition is also imposed across a cell to indicate a mean\neffective force due to the nearby swimmers. At suitable values of this\nstress-jump coefficient, the relative increase of the migration velocity and\nswimming efficiency is noticeably higher at an optimum occupancy.",
        "positive": "Medial packing and elastic asymmetry stabilize the double-gyroid in\n  block copolymers: Triply-periodic networks are among the most complex and functionally valuable\nself-assembled morphologies, yet they form in nearly every class of biological\nand synthetic soft matter building blocks. In contrast to simpler assembly\nmotifs -- spheres, cylinders, layers -- TPN assemblies require molecules to\noccupy variable local domain shapes, confounding attempts to understand their\nformation. Here, we examine the double-gyroid (DG) network phase of block\ncopolymer (BCP) melts, a prototypical soft self-assembly system, by using a\ngeometric formulation of the strong stretching theory (SST) of BCP melts. The\ntheory establishes the direct link between molecular BCP packing,\nthermodynamics of melt assembly and the {\\it medial map}, a generic geometric\nmeasure of the center of complex shapes. We show that \"medial packing\" is\nessential for thermodynamic stability of DG in strongly-segregated melts,\nreconciling a long-standing contradiction between infinite- and\nfinite-segregation theories, corroborating our SST predictions at\nfinite-segregation via self-consistent field calculations. Additionally, we\nfind a previously unrecognized non-monotonic dependence of DG stability on the\nelastic asymmetry, the comparative entropic stiffness of matrix-forming to\ntubular-network forming blocks. The composition window of stable DG --\nintermediate to competitor lamellar and columnar phases -- widens both for\nlarge and small elastic asymmetry, seemingly overturning the heuristic view\nthat packing frustration is localized to the tubular domains. This study\ndemonstrates utility of geometric optimization of {\\it medial tesselations} for\nunderstanding in soft-molecular assembly. As such, the particular medial-based\napproach deployed here is readily generalizable to study packing frustration\nfar beyond the case of DG morphologies in neat BCP assemblies."
    },
    {
        "anchor": "A study for the static properties of symmetric linear multiblock\n  copolymers under poor solvent conditions: We use a standard bead-spring model and molecular dynamics simulations to\nstudy the static properties of symmetric linear multiblock copolymer chains and\ntheir blocks under poor solvent conditions in a dilute solution from the regime\nclose to theta conditions, where the chains adopt a coil-like formation, to the\npoorer solvent regime where the chains collapse obtaining a globular formation\nand phase separation between the blocks occurs. We choose interaction\nparameters as is done for a standard model, i.e., the Lennard-Jones fluid and\nwe consider symmetric chains, i.e., the multiblock copolymer consists of an\neven number $n$ of alternating chemically different A and B blocks of the same\nlength $N_{A}=N_{B}=N$. We show how usual static properties of the individual\nblocks and the whole multiblock chain can reflect the phase behavior of such\nmacromolecules. Also, how parameters, such as the number of blocks $n$ can\naffect properties of the individual blocks, when chains are in a poor solvent\nfor a certain range of $n$. A detailed discussion of the static properties of\nthese symmetric multiblock copolymers is also given. Our results in combination\nwith recent simulation results on the behavior of multiblock copolymer chains\nprovide a complete picture for the behavior of these macromolecules under poor\nsolvent conditions, at least for this most symmetrical case. Due to the\nstandard choice of our parameters, our system can be used as a benchmark for\nrelated models, which aim at capturing the basic aspects of the behavior of\nvarious biological systems.",
        "positive": "Scale-free chaos in the 2D harmonically confined Vicsek model: Animal motion and flocking are ubiquitous nonequilibrium phenomena that are\noften studied within active matter. In examples such as insect swarms,\nmacroscopic quantities exhibit power laws with measurable critical exponents\nand ideas from phase transitions and statistical mechanics have been explored\nto explain them. The widely used Vicsek model with periodic boundary conditions\nhas an ordering phase transition but the corresponding homogeneous ordered or\ndisordered phases are different from observations of natural swarms. If a\nharmonic potential (instead of a periodic box) is used to confine particles,\nthe numerical simulations of the Vicsek model display periodic, quasiperiodic\nand chaotic attractors. The latter are scale free on critical curves that\nproduce power laws and critical exponents. Here we investigate the\nscale-free-chaos phase transition in two space dimensions. We show that the\nshape of the chaotic swarm on the critical curve reflects the split between\ncore and vapor of insects observed in midge swarms and that the dynamic\ncorrelation function collapses only for a finite interval of small scaled\ntimes, as also observed. We explain the algorithms used to calculate the\nlargest Lyapunov exponents, the static and dynamic critical exponents and\ncompare them to those of the three-dimensional model."
    },
    {
        "anchor": "Ordering of adsorbed rigid rods mediated by the Boussinesq interaction\n  on a soft substrate: Orientational ordering driven by mechanical distortion of soft substrates\nplays a major role in material transformation processes such as\nelastocapillarity and surface anchoring. We present a theoretical model of the\norientational response of anisotropic rods deposited onto a surface of a soft,\nelastic substrate of finite thickness. We show that anisotropic rods exhibit a\ncontinuous isotropic-nematic phase transition, driven by orientational\ninteractions between surface deposited rods. This interaction is mediated by\nthe deformation of the underlying elastic substrate, and is quantified by the\nBoussinesq solution adapted to the case of slender, surface deposited rods.\nFrom the microscopic rod-rod interactions we derive the appropriate Maier-Saupe\nmean-field description, which includes the Boussinesq elastic free-energy\ncontribution due to the substrate elasticity, derive the conditions for the\nexistence of a continuous orientational ordering transition and discuss the\nimplication of results in the soft (bio) systems context.",
        "positive": "A quaternion-based continuation method to follow the equilibria and\n  stability of slender elastic rods: We present a theoretical and numerical framework to compute bifurcations of\nequilibria and stability of slender elastic rods. The 3D kinematics of the rod\nis treated in a geometrically exact way by parameterizing the position of the\ncenterline and making use of quaternions to represent the orientation of the\nmaterial frame. The equilibrium equations and the stability of their solutions\nare derived from the mechanical energy which takes into account the\ncontributions due to internal moments (bending and twist), external forces and\ntorques. Our use of quaternions allows for the equilibrium equations to be\nwritten in a simple quadratic form and solved efficiently with an asymptotic\nnumerical continuation method. This finite element perturbation method gives\ninteractive access to semi-analytical equilibrium branches, in contrast with\nthe individual solution points obtained from classical minimization or\npredictor-corrector techniques. By way of example, we apply our numerics to\naddress the specific problem of a naturally curved rod under extreme twisting\nand perform a detailed comparison against our own precision model experiments\nof this system. Excellent quantitative agreement is found between experiments\nand simulations for the underlying 3D buckling instabilities and the\ncharacterization of the resulting complex configurations."
    },
    {
        "anchor": "Banding, Excitability and Chaos in Active Nematic Suspensions: Motivated by the observation of highly unstable flowing states in suspensions\nof microtubules and kinesin, we analyze a model of mutually-propelled filaments\nsuspended in a solvent. The system undergoes a mean-field isotropic-nematic\ntransition for large enough filament concentrations when the nematic order\nparameter is allowed to vary in space and time. We analyze the model in two\ncontexts: a quasi-one-dimensional channel with no-slip walls and a\ntwo-dimensional box with periodic boundaries. Using stability analysis and\nnumerical calculations we show that the interplay between non-uniform nematic\norder, activity, and flow results in a variety of complex scenarios that\ninclude spontaneous banded laminar flow, relaxation oscillations, and chaos.",
        "positive": "Stochastic model for nucleosome sliding in the presence of DNA ligands: Heat-induced mobility of nucleosomes along DNA is an experimentally\nwell-studied phenomenon. A recent experiment shows that the repositioning is\nmodified in the presence of minor-groove binding DNA ligands. We present here a\nstochastic three-state model for the diffusion of a nucleosome along DNA in the\npresence of such ligands. It allows us to describe the dynamics and the steady\nstate of such a motion analytically. The analytical results are in excellent\nagreement with numerical simulations of this stochastic process.With this\nmodel, we study the response of a nucleosome to an external force and how it is\naffected by the presence of ligands."
    },
    {
        "anchor": "Nonlinear dynamics and rheology of active fluids: simulations in two\n  dimensions: We report simulations of a continuum model for (apolar, flow aligning) active\nfluids in two dimensions. Both free and anchored boundary conditions are\nconsidered, at parallel confining walls that are either static or moving at\nfixed relative velocity. We focus on extensile materials and find that steady\nshear bands, previously shown to arise ubiquitously in 1D for the active\nnematic phase at small (or indeed zero) shear rate, are generally replaced in\n2D by more complex flow patterns that can be stationary, oscillatory, or\napparently chaotic. The consequences of these flow patterns for time-averaged\nsteady-state rheology are examined.",
        "positive": "Loss of material trainability through an unusual transition: Material training is a method to endow materials with specific responses\nthrough external driving. We study the complexity of attainable responses, as\nexpressed in the number of sites that are simultaneously controlled. With\nincreased complexity, convergence to the desired response becomes very slow.\nThe training error decays as a power-law with an exponent that varies\ncontinuously and vanishes at a critical threshold, marking the limit of\ntrainable responses. We study how the transition affects the vibrational\nproperties. Approaching the critical threshold, low frequency modes\nproliferate, approaching zero frequency. This implies that training causes\nmaterial degradation and that training fails due to competing spurious low\nfrequency modes. We propose that the excess low frequency spectrum is due to\natypical local structures with bonds that nearly align. Our work explains how\nthe presence of an exotic critical point affects the convergence of training,\nand could be relevant for understanding learning in physical systems."
    },
    {
        "anchor": "Field induced stationary state for an accelerated tracer in a bath: Our interest goes to the behavior of a tracer particle, accelerated by a\nconstant and uniform external field, when the energy injected by the field is\nredistributed through collision to a bath of unaccelerated particles. A non\nequilibrium steady state is thereby reached. Solutions of a generalized\nBoltzmann-Lorentz equation are analyzed analytically, in a versatile framework\nthat embeds the majority of tracer-bath interactions discussed in the\nliterature. These results --mostly derived for a one dimensional system-- are\nsuccessfully confronted to those of three independent numerical simulation\nmethods: a direct iterative solution, Gillespie algorithm, and the Direct\nSimulation Monte Carlo technique. We work out the diffusion properties as well\nas the velocity tails: large v, and either large -v, or v in the vicinity of\nits lower cutoff whenever the velocity distribution is bounded from below.\nParticular emphasis is put on the cold bath limit, with scatterers at rest,\nwhich plays a special role in our model.",
        "positive": "Exact results for non-Newtonian transport properties in sheared granular\n  suspensions: inelastic Maxwell models and BGK-type kinetic model: The Boltzmann kinetic equation for dilute granular suspensions under simple\n(or uniform) shear flow (USF) is considered to determine the non-Newtonian\ntransport properties of the system. In contrast to previous attempts based on a\ncoarse-grained description, our suspension model accounts for the real\ncollisions between grains and particles of the surrounding molecular gas. The\nlatter is modeled as a bath (or thermostat) of elastic hard spheres at a given\ntemperature. Two independent but complementary approaches are followed to reach\nexact expressions for the rheological properties. First, the Boltzmann equation\nfor the so-called inelastic Maxwell models (IMM) is considered. The fact that\nthe collision rate of IMM is independent of the relative velocity of the\ncolliding spheres allows us to exactly compute the collisional moments of the\nBoltzmann operator without the knowledge of the distribution function. Thanks\nto this property the transport properties of the sheared granular suspension\ncan be \\emph{exactly} determined. As a second approach, a\nBhatnagar--Gross--Krook (BGK)-type kinetic model adapted to granular\nsuspensions is solved to compute the velocity moments and the velocity\ndistribution function of the system. The theoretical results show in general a\ngood agreement with the approximate analytical results derived for inelastic\nhard spheres (IHS) by means of Grad's moment method and with computer\nsimulations performed in the Brownian limiting case ($m/m_g\\to \\infty$, where\n$m_g$ and $m$ are the masses of the particles of the molecular and granular\ngases, respectively). In addition, as expected the IMM and BGK results show\nthat the temperature and non-Newtonian viscosity exhibit and $S$ shape in a\nplane of stress-strain rate (discontinuous shear thickening, DST). The DST\neffect becomes more pronounced as the mass ratio $m/m_g$ increases."
    },
    {
        "anchor": "Multi-defect Dynamics in Active Nematics: Recent experiments and numerical studies have drawn attention to the dynamics\nof active nematics. Two-dimensional active nematics flow spontaneously and\nexhibit spatiotemporal chaotic flows with proliferation of topological defects\nin the nematic texture. It has been proposed that the dynamics of active\nnematics can be understood in terms of the dynamics of interacting defects,\npropelled by active stress. Previous work has derived effective equations of\nmotion for individual defects as quasi-particles moving in the mean field\ngenerated by other defects, but an effective theory governing multi-defect\ndynamics has remained out of reach. In this paper, we examine the dynamics of\n2D active nematics in the limit of strong order and overdamped compressible\nflow. The activity-induced defect dynamics is formulated as a perturbation of\nthe manifold of quasi-static nematic textures explicitly parameterized by\ndefect positions. This makes it possible to derive a set of coupled ordinary\ndifferential equations governing defect (and therefore texture) dynamics.\nInterestingly, because of the non-orthogonality of textures associated with\nindividual defects, their motion is coupled through a position dependent\n``collective mobility\" matrix. In addition to the familiar active\nself-propulsion of the $+1/2$ defect, we obtain new collective effects of\nactivity that can be interpreted in terms of non-central and non-reciprocal\ninteractions between defects.",
        "positive": "Shape and symmetry determine two-dimensional melting transitions of hard\n  regular polygons: The melting transition of two-dimensional (2D) systems is a fundamental\nproblem in condensed matter and statistical physics that has advanced\nsignificantly through the application of computational resources and\nalgorithms. 2D systems present the opportunity for novel phases and phase\ntransition scenarios not observed in 3D systems, but these phases depend\nsensitively on the system and thus predicting how any given 2D system will\nbehave remains a challenge. Here we report a comprehensive simulation study of\nthe phase behavior near the melting transition of all hard regular polygons\nwith $3\\leq n\\leq 14$ vertices using massively parallel Monte Carlo simulations\nof up to one million particles. By investigating this family of shapes, we show\nthat the melting transition depends upon both particle shape and symmetry\nconsiderations, which together can predict which of three different melting\nscenarios will occur for a given $n$. We show that systems of polygons with as\nfew as seven edges behave like hard disks; they melt continuously from a solid\nto a hexatic fluid and then undergo a first-order transition from the hexatic\nphase to the fluid phase. We show that this behavior, which holds for all\n$7\\leq n\\leq 14$, arises from weak entropic forces among the particles. Strong\ndirectional entropic forces align polygons with fewer than seven edges and\nimpose local order in the fluid. These forces can enhance or suppress the\ndiscontinuous character of the transition depending on whether the local order\nin the fluid is compatible with the local order in the solid. As a result,\nsystems of triangles, squares, and hexagons exhibit a KTHNY-type continuous\ntransition between fluid and hexatic, tetratic, and hexatic phases,\nrespectively, and a continuous transition from the appropriate \"x\"-atic to the\nsolid. [abstract truncated due to arxiv length limitations]."
    },
    {
        "anchor": "A soft-lithographed chaotic electrokinetic micromixer for efficient\n  chemical reactions in lab-on-chips: Mixing is one of the basic functions which automated lab-on-chips require for\nthe effective management of liquid samples. In this paper we report on the\nworking principle, design, fabrication and experimental characterization of a\nsoft-lithographed micromixer for microfluidic applications. The device\neffectively mixes two liquids by means of chaotic advection obtained as an\nimplementation of a Linked Twisted Map (LTM). In this sense it is chaotic. The\nliquids are electrokinetically displaced by generating rolls through AC\nelectroosmosis on co-planar electrodes. The device performance has been tested\non dyed DI-water for several voltages, frequencies and flow-rates, displaying\ngood mixing properties in the range of $10 \\div 100$kHz, at low peak-to-peak\nvoltages ($\\sim15 \\div 20$ volts). Low voltage supply, small dimensions and\npossibility of fabrication via standard lithographic techniques make the device\nhighly integrable in lab-on-a-chip platforms.",
        "positive": "Rearrangements during slow compression of a jammed two-dimensional\n  emulsion: As amorphous materials get jammed, both geometric and dynamic heterogeneity\nare observed. We investigate the correlation between the local geometric\nheterogeneity and local rearrangements in a slowly compressed bidisperse\nquasi-two-dimensional emulsion system. The compression is driven by evaporation\nof the continuous phase, and causes the area packing fraction to increase from\n0.88 to 0.99. We quantify the structural heterogeneity of the system using the\nradical Voronoi tessellation following the method of [Rieser et al., Phys. Rev.\nLett. 116, 088001 (2016)]. We define two structural quantities characterizing\nlocal structure, the first which considers nearest neighbors and the second of\nwhich includes information from second nearest neighbors. We find that droplets\nin heterogeneous local regions are more likely to have local rearrangements.\nThese rearrangements are generally T1 events where two droplets converge toward\na void, and two droplets move away from the void to make room for the\nconverging droplets. Thus the presence of the voids tends to orient the T1\nevents. The presence of a correlation between the structural quantities and the\nrearrangement dynamics remains qualitatively unchanged over the entire range of\npacking fractions observed."
    },
    {
        "anchor": "Permeative flows in cholesteric liquid crystals: We use lattice Boltzmann simulations to solve the Beris-Edwards equations of\nmotion for a cholesteric liquid crystal subjected to Poiseuille flow along the\ndirection of the helical axis (permeative flow). The results allow us to\nclarify and extend the approximate analytic treatments currently available. We\nfind that if the cholesteric helix is pinned at the boundaries there is an\nenormous viscosity increase. If, instead, the helix is free the velocity\nprofile is flattened but the viscosity is essentially unchanged. We highlight\nthe importance of secondary flows and, for higher flow velocities, we identify\na flow-induced double twist structure in the director field -- reminiscent of\nthe texture characteristic of blue phases.",
        "positive": "Budding of domains in mixed bilayer membranes: We propose a model that accounts for budding behavior of domains in lipid\nbilayers, where each of the bilayer leaflets has a coupling between its local\ncurvature and local lipid composition. The compositional asymmetry between the\ntwo monolayers leads to an overall spontaneous curvature. The membrane\nfree-energy contains three contributions: bending energy, line tension, and a\nLandau free-energy for a lateral phase separation. Within a mean-field\ntreatment, we obtain various phase diagrams which contain fully-budded, dimpled\nand flat states. In particular, for some range of membrane parameters, the\nphase diagrams exhibit a tricritical behavior as well as three-phase\ncoexistence region. The global phase diagrams can be divided into three types\nand are analyzed in terms of the curvature-composition coupling parameter and\ndomain size."
    },
    {
        "anchor": "Fluctuating-friction molecular motors: We show that the correlated stochastic fluctuation of the friction\ncoefficient can give rise to long-range directional motion of a particle\nundergoing Brownian random walk in a constant periodic energy potential\nlandscape. The occurrence of this motion requires the presence of two\nadditional independent bodies interacting with the particle via friction and\nvia the energy potential, respectively, which can move relative to each other.\nSuch three-body system generalizes the classical Brownian ratchet mechanism,\nwhich requires only two interacting bodies. In particular, we describe a simple\ntwo-level model of fluctuating-friction molecular motor that can be solved\nanalytically. In our previous work [M.K., L.M and D.P. 2000 J. Nonlinear Opt.\nPhys. Mater. vol. 9, 157] this model has been first applied to understanding\nthe fundamental mechanism of the photoinduced reorientation of dye-doped liquid\ncrystals. Applications of the same idea to other fields such as molecular\nbiology and nanotechnology can however be envisioned. As an example, in this\npaper we work out a model of the actomyosin system based on the\nfluctuating-friction mechanism.",
        "positive": "Role of solvation in pressure-induced helix stabilization: In contrast to the well-known destabilization of globular proteins by high\npressure, re- cent work has shown that pressure stabilizes the formation of\nisolated {\\alpha}-helices. However all simulations to date have obtained a\nqualitatively opposite result within the experimen- tal pressure range. We show\nthat using a protein force field (Amber03w) parametrized in conjunction with an\naccurate water model (TIP4P/2005) recovers the correct pressure- dependence and\nan overall stability diagram for helix formation similar to that from experi-\nment; on the other hand, we confirm that using TIP3P water results in a very\nweak pressure destabilization of helices. By carefully analyzing the\ncontributing factors, we show that this is not merely a consequence of\ndifferent peptide conformations sampled using TIP3P. Rather, there is a\ncritical role for the solvent itself in determining the dependence of total\nsystem volume (peptide and solvent) on helix content. Helical peptide\nstructures exclude a smaller volume to water, relative to non-helical\nstructures with both the water models, but the total system volume for helical\nconformations is higher than non-helical conformations with TIP3P water at low\nto intermediate pressures, in contrast to TIP4P/2005 water. Our results further\nemphasize the importance of using an accurate water model to study protein\nfolding under conditions away from standard temperature and pressure."
    },
    {
        "anchor": "Finger behavior of a shear thinning fluid in a Hele-Shaw cell: We make a theoretical study of the behavior of a simple fluid displacing a\nshear thinning fluid confined in a Hele-Shaw cell. To study the Saffman-Taylor\ninstability when the displaced fluid is non Newtonian we face the problem of\nhaving a field which is non laplacian. By means of an hodographic\ntransformation we are able to solve the problem in the case of weak shear\nthinning while taking into account the non laplacian character of the equation.\nOur results predict that the finger width decreases towards zero for small\nvalues of the surface tension parameter which is inversely proportional to the\nfinger velocity.",
        "positive": "Amphiphiles at Interfaces: Simulation of Structure and Phase Behavior: Computer simulations of coarse-grained molecular models for amphiphilic\nsystems can provide insight into the the structure of amphiphiles at\ninterfaces. They can help to identify the factors that determine the phase\nbehavior, and they can bridge between atomic descriptions and phenomenological\nfield theories.\n  Here we focus on model systems for amphiphilic membranes. After a brief\ngeneral introduction, we present selected simulation results on monolayers,\nbilayers, and bilayer stacks. First, we discuss internal phase transitions in\nmembranes and show that idealized models reproduce the generic phase behavior.\nThen we consider membrane fluctuations and membrane defects. The simulation\ndata is compared with mesoscopic theories, and effective phenomenological\nparameters can be extracted."
    },
    {
        "anchor": "Self-Diffusion Scalings in Dense Granular Flows: We report on measurements of self-diffusion coefficients in discrete\nnumerical simulations of steady, homogeneous, collisional shearing flows of\nnearly identical, frictional, inelastic spheres. We focus on a range of\nrelatively high solid volume fractions that are important in those terrestrial\ngravitational shearing flows that are dominated by collisional interactions.\nDiffusion over this range of solid fraction has not been well characterized in\nprevious studies. We first compare the measured values with an empirical\nscaling based on shear rate previously proposed in the literature, and\nhighlight the presence of anisotropy and the solid fraction dependence. We then\ncompare the numerical measurements with those predicted by the kinetic theory\nfor shearing flows of inelastic spheres and offer an explanation for why the\nmeasured and predicted values differ.",
        "positive": "Multiscale modeling of a rectifying bipolar nanopore: Comparing\n  Poisson-Nernst-Planck to Monte Carlo: In the framework of a multiscale modeling approach, we present a systematic\nstudy of a bipolar rectifying nanopore using a continuum and a particle\nsimulation method. The common ground in the two methods is the application of\nthe Nernst-Planck (NP) equation to compute ion transport in the framework of\nthe implicit-water electrolyte model. The difference is that the\nPoisson-Boltzmann theory is used in the Poisson-Nernst-Planck (PNP) approach,\nwhile the Local Equilibrium Monte Carlo (LEMC) method is used in the particle\nsimulation approach (NP+LEMC) to relate the concentration profile to the\nelectrochemical potential profile. Since we consider a bipolar pore which is\nshort and narrow, we perform simulations using two-dimensional PNP. In\naddition, results of a non-linear version of PNP that takes crowding of ions\ninto account are shown. We observe that the mean field approximation applied in\nPNP is appropriate to reproduce the basic behavior of the bipolar nanopore\n(e.g., rectification) for varying parameters of the system (voltage, surface\ncharge, electrolyte concentration, and pore radius). We present current data\nthat characterize the nanopore's behavior as a device, as well as\nconcentration, electrical potential, and electrochemical potential profiles."
    },
    {
        "anchor": "The mechanical response of fire ant rafts: Fire ants (Solenopsis invicta) cohesively aggregate via the formation of\nvoluntary ant-to-ant attachments when under confinement or exposed to water.\nOnce formed, these aggregations act as viscoelastic solids due to dynamic bond\nexchange between neighboring ants as demonstrated by rate-dependent mechanical\nresponse of 3D aggregations, confined in rheometers. We here investigate the\nmechanical response of 2D, planar ant rafts roughly as they form in nature.\nSpecifically, we load rafts under uniaxial tension to failure, as well as to\n50% strain for two cycles with various recovery times between. We do so while\nmeasuring raft reaction force (to estimate network-scale stress), as well as\nthe networks' instantaneous velocity fields and topological damage responses to\nelucidate the ant-scale origins of global mechanics. The rafts display\nbrittle-like behavior even at slow strain rates (relative to the unloaded bond\ndetachment rate) for which Transient Network Theory predicts steady-state\ncreep. This provides evidence that loaded ant-to-ant bonds undergo\nmechanosensitive bond stabilization or act as \\say{catch bonds}. This is\nfurther supported by the coalescence of voids that nucleate due to biaxial\nstress conditions and merge due to bond dissociation. The characteristic\ntimescales of void coalescence due to chain dissociation provide evidence that\nthe local detachment of stretched bonds is predominantly strain- (as opposed to\nbond lifetime-) dependent, even at slow strain rates, implying that bond\ndetachment rates diminish significantly under stretch. Significantly, when the\nvoids are closed by restoring the rafts to unstressed conditions, mechanical\nrecovery occurs, confirming the presence of concentration-dependent bond\nassociation that - combined with force-diminished dissociation - could further\nbolster network cohesion under certain stress states.",
        "positive": "Jamming in confined geometry: Criticality of the jamming transition and\n  implications of structural relaxation in confined supercooled liquids: In marginally jammed solids confined by walls, we calculate the particle and\nensemble averaged value of an order parameter, $\\left<\\Psi(r)\\right>$, as a\nfunction of the distance to the wall, $r$. Being a microscopic indicator of\nstructural disorder and particle mobility in solids, $\\Psi$ is by definition\nthe response of the mean square particle displacement to the increase of\ntemperature in the harmonic approximation and can be directly calculated from\nthe normal modes of vibration of the zero-temperature solids. We find that, in\nconfined jammed solids, $\\left<\\Psi(r)\\right>$ curves at different pressures\ncan collapse onto the same master curve following a scaling function,\nindicating the criticality of the jamming transition. The scaling collapse\nsuggests a diverging length scale and marginal instability at the jamming\ntransition, which should be accessible to sophisticatedly designed experiments.\nMoreover, $\\left<\\Psi(r)\\right>$ is found to be significantly suppressed when\napproaching the wall and anisotropic in directions perpendicular and parallel\nto the wall. This finding can be applied to understand the $r$-dependence and\nanisotropy of the structural relaxation in confined supercooled liquids,\nproviding another example of understanding or predicting behaviors of\nsupercooled liquids from the perspective of the zero-temperature amorphous\nsolids."
    },
    {
        "anchor": "Two-dimensional Packing in Prolate Granular Materials: We investigate the two-dimensional packing of extremely prolate (aspect ratio\n$\\alpha=L/D>10$) granular materials, comparing experiments with Monte-Carlo\nsimulations. The average packing fraction of particles with aspect ratio\n$\\alpha=12$ is $0.68\\pm0.03$. We quantify the orientational correlation of\nparticles and find a correlation length of two particle lengths. The functional\nform of the decay of orientational correlation is the same in both experiments\nand simulations spanning three orders of magnitude in aspect ratio. This\nfunction decays over a distance of two particle lengths. It is possible to\nidentify voids in the pile with sizes ranging over two orders of magnitude. The\nexperimental void distribution function is a power law with exponent\n$-\\beta=-2.43\\pm0.08$. Void distributions in simulated piles do not decay as a\npower law, but do show a broad tail. We extend the simulation to investigate\nthe scaling at very large aspect ratios. A geometric argument predicts the pile\nnumber density to scale as $\\alpha^{-2}$. Simulations do indeed scale this way,\nbut particle alignment complicates the picture, and the actual number densities\nare quite a bit larger than predicted.",
        "positive": "Diffusion Anomaly in a three dimensional lattice gas: We investigate the relation between thermodynamic and dynamic properties of\nan associating lattice gas (ALG) model. The ALG combines a three dimensional\nlattice gas with particles interacting through a soft core potential and\norientational degrees of freedom. From the competition between the directional\nattractive forces and the soft core potential results two liquid phases, double\ncriticality and density anomaly. We study the mobility of the molecules in this\nmodel by calculating the diffusion constant at a constant temperature, $D$. We\nshow that $D$ has a maximum at a density $\\rho_{max}$ and a minimum at a\ndensity $\\rho_{min}<\\rho_{max}$. Between these densities the diffusivity\ndiffers from the one expected for normal liquids. We also show that in the\npressure-temperature phase-diagram the line of extrema in diffusivity is close\nto the liquid-liquid critical point and it is partially inside the temperature\nof maximum density (TMD) line."
    },
    {
        "anchor": "Barrier-Controlled Non-Equilibrium Criticality in Reactive Particle\n  Systems: Non-equilibrium critical phenomena generally exist in many dynamic systems,\nlike chemical reactions and some driven-dissipative {reactive} particle\nsystems. Here, by using computer simulation and theoretical analysis, we\ndemonstrate the crucial role of the activation barrier on the criticality of\ndynamic phase transitions in a minimal reactive hard-sphere model. We find that\nat zero thermal noise, with increasing the activation barrier, the type of\ntransition changes from a continuous conserved directed percolation into a\ndiscontinuous dynamic transition by crossing a \\emph{tricritical} point. A\nmean-field theory combined with field-simulation is proposed to explain this\nphenomenon. The possibility of Ising-type criticality in the non-equilibrium\nsystem at finite thermal noise is also discussed.",
        "positive": "Tack energy and switchable adhesion of liquid crystal elastomers: The mechanical properties of liquid crystal elastomers (LCEs) make them\nsuitable candidates for pressure-sensitive adhesives (PSAs). Using the nematic\ndumbbell constitutive model, and the block model of PSAs, we study their tack\nenergy and the debonding process as could be measured experimentally in the\nprobe-tack test. To investigate their performance as switchable PSAs we compare\nthe tack energy for the director aligned parallel, and perpendicular to the\nsubstrate normal, and for the isotropic state. We find that the tack energy is\nlarger in the parallel alignment than the isotropic case by over a factor of\ntwo. The tack energy for the perpendicular alignment can be 50% less than the\nisotropic case. We propose a mechanism for reversibly switchable adhesion based\non the reversibility of the isotropic to nematic transition. Finally we\nconsider the influence of several material parameters that could be used to\ntune the stress-strain response."
    },
    {
        "anchor": "Compression stiffening of fibrous networks with stiff inclusions: Tissues commonly consist of cells embedded within a fibrous biopolymer\nnetwork. Whereas cell-free reconstituted biopolymer networks typically soften\nunder applied uniaxial compression, various tissues, including liver, brain,\nand fat, have been observed to instead stiffen when compressed. The mechanism\nfor this compression stiffening effect is not yet clear. Here, we demonstrate\nthat when a material composed of stiff inclusions embedded in a fibrous network\nis compressed, heterogeneous rearrangement of the inclusions can induce tension\nwithin the interstitial network, leading to a macroscopic crossover from an\ninitial bending-dominated softening regime to a stretching-dominated stiffening\nregime, which occurs before and independently of jamming of the inclusions.\nUsing a coarse-grained particle-network model, we first establish a phase\ndiagram for compression-driven, stretching-dominated stress propagation and\njamming in uniaxially compressed 2- and 3-dimensional systems. Then, we\ndemonstrate that a more detailed computational model of stiff inclusions in a\nsubisostatic semiflexible fiber network exhibits quantitative agreement with\nthe predictions of our coarse-grained model as well as qualitative agreement\nwith experiments.",
        "positive": "Aging and Energy Landscapes: Application to Liquids and Glasses: The equation of state for a liquid in equilibrium, written in the potential\nenergy landscape formalism, is generalized to describe out-of-equilibrium\nconditions. The hypothesis that during aging the system explores basins\nassociated to equilibrium configurations is the key ingredient in the\nderivation. Theoretical predictions are successfully compared with data from\nmolecular dynamics simulations of different aging processes, such as\ntemperature and pressure jumps."
    },
    {
        "anchor": "Self-assembly of Freely-rotating Polydisperse Cuboids: Unveiling the\n  Boundaries of the Biaxial Nematic Phase: Colloidal cuboids have the potential to self-assemble into biaxial liquid\ncrystal phases, which exhibit two independent optical axes. Over the last few\ndecades, several theoretical works predicted the existence of a wide region of\nthe phase diagram where the biaxial nematic phase would be stable, but imposed\nrather strong constraints on the particle rotational degrees of freedom. In\nthis work, we employ molecular simulation to investigate the impact of size\ndispersity on the phase behaviour of freely-rotating hard cuboids, here\nmodelled as self-dual-shaped nanoboards. This peculiar anisotropy, exactly in\nbetween oblate and prolate geometry, has been proposed as the most appropriate\nto promote phase biaxiality. We observe that size dispersity radically changes\nthe phase behaviour of monodisperse systems and leads to the formation of the\nelusive biaxial nematic phase, being found in an large region of the packing\nfraction vs polydispersity phase diagram. Although our results confirm the\ntendencies reported in past experimental observations on colloidal dispersions\nof slightly prolate goethite particles, they cannot reproduce the direct\nisotropic-to-biaxial nematic phase transition observed in these experiments.",
        "positive": "Nanorheology : an Investigation of the Boundary Condition at Hydrophobic\n  and Hydrophilic Interfaces: t has been shown that the flow of a simple liquid over a solid surface can\nviolate the so-called no-slip boundary condition. We investigate the flow of\npolar liquids, water and glycerol, on a hydrophilic Pyrex surface and a\nhydrophobic surface made of a Self-Assembled Monolayer of OTS\n(octadecyltrichlorosilane) on Pyrex. We use a Dynamic Surface Force Apparatus\n(DSFA) which allows one to study the flow of a liquid film confined between two\nsurfaces with a nanometer resolution. No-slip boundary conditions are found for\nboth fluids on hydrophilic surfaces only. Significant slip is found on the\nhydrophobic surfaces, with a typical length of one hundred nanometers."
    },
    {
        "anchor": "Age-independent process in aging hard-sphere suspensions; The\n  beta-process and its ramifications: We consider the dynamics of a suspension of hard sphere-like particles in the\nproximity of its glass transition, the region where the intermediate scattering\nfunctions show significant aging. The time correlation function of the\nlongitudinal particle current shows no dependence on age and reveals behaviour\nof ideal super-packed fluid and glass. The power laws of the beta process of\nthe idealised mode coupling theory are exposed directly without reliance on\nfitting parameters. We proffer a mechanism linking the reversible/ageless\ndynamics, which constitutes the beta-process, and the irreversible aging\ndynamics. The latter verifies predictions of spin-glass theories.",
        "positive": "Co-assembly of Janus nanoparticles in block copolymer systems: Block copolymer are ideal matrices to control the localisation of colloids.\nFurthermore, anisotropic nanoparticles such as Janus nanoparticles possess an\nadditional orientational degree of freedom that can play a crucial role in the\nformation of highly ordered materials made of block copolymers. This work\npresents a mesoscopic simulation method to assert the co-assembly of Janus\nnanoparticles in a block copolymer mixture, finding numerous instances of\naggregation and formation of ordered configurations which can be related to\ndispersions of pure Janus colloids. Comparison with chemically homogeneous\nneutral nanoparticles determines that Janus nanoparticles are less prone to\ninduce bridging along lamellar domains, thus being a less destructive way to\nsegregate nanoparticles at interfaces. The combination of asymmetric block\ncopolymer and asymmetric Janus nanoparticles can result in assembly of colloids\nin an even number of layers within one of the block domains."
    },
    {
        "anchor": "Irreducible Representations Of Oscillatory And Swirling Flows In Active\n  Soft Matter: Recent experiments imaging fluid flow around swimming microorganisms have\nrevealed complex time-dependent velocity fields that differ qualitatively from\nthe stresslet flow commonly employed in theoretical descriptions of active\nmatter. Here we obtain the most general flow around a finite sized active\nparticle by expanding the surface stress in irreducible Cartesian tensors. This\nexpansion, whose first term is the stresslet, must include, respectively,\nthird-rank polar and axial tensors to minimally capture crucial features of the\nactive oscillatory flow around translating Chlamydomonas and the active\nswirling flow around rotating Volvox. The representation provides explicit\nexpressions for the irreducible symmetric, antisymmetric and isotropic parts of\nthe continuum active stress. Antisymmetric active stresses do not conserve\norbital angular momentum and our work thus shows that spin angular momentum is\nnecessary to restore angular momentum conservation in continuum hydrodynamic\ndescriptions of active soft matter.",
        "positive": "Hysteretic wavelength selection in isometric, unsupported radial\n  wrinkling: In [Pal et al., arXiv:2206.03552], the authors discuss how an unsupported\nflat annulus contracted at its inner boundary by a factor $\\Delta$, buckles\ninto a radial wrinkling pattern that is fully isometric and tension-free. What\nselects the wavelength in such a pure-bending configuration, in the absence of\nany competing sources of work? In this paper, with the support of numerical\nsimulations, we argue that competition between stretching and bending energies\nat local, mesoscopic scales leads to the selection of a wavelength scale\n$\\lambda^*$ sensitive to both the width $w$ and thickness $t$ of the sheet:\n$\\lambda^* \\sim w^{2/3} t^{1/3} \\Delta^{-1/6}$. This scale $\\lambda^*$\ncorresponds to an arrest criterion for wrinkle coarsening starting from any\nwavelength $\\lambda \\lesssim \\lambda^*$, which can be interpreted in terms of\nboth size and energetic barriers to further coarsening. However, the sheet can\nsupport coarser wavelengths: $\\lambda \\gtrsim \\lambda^*$, since there is no\npenalty to their existence. Since this wavelength selection mechanism depends\non the value of $\\lambda$ itself, it is hysteretic."
    },
    {
        "anchor": "Brownian dynamics simulations to explore experimental microsphere\n  diffusion with optical tweezers: We develop two-dimensional Brownian dynamics simulations to examine the\nmotion of disks under thermal fluctuations and Hookean forces. Our simulations\nare designed to be experimental-like, since the experimental conditions define\nthe available time-scales which characterize the solution of Langevin\nequations. To define the fluid model and methodology, we explain the basics of\nthe theory of Brownian motion applicable to quasi-twodimensional diffusion of\noptically-trapped microspheres. Using the data produced by the simulations, we\npropose an alternative methodology to calculate diffusion coefficients. We\nobtain that, using typical input parameters in video-microscopy experiments,\nthe averaged values of the diffusion coefficient differ from the theoretical\none less than a 1\\%.",
        "positive": "Thermo-hydrodynamic non-equilibrium effects on compressible\n  Rayleigh-Taylor instability: The effects of compressibility on Rayleigh-Taylor instability (RTI) are\ninvestigated by inspecting the interplay between thermodynamic and hydrodynamic\nnon-equilibrium phenomena (TNE, HNE, respectively) via a discrete Boltzmann\nmodel (DBM). Two effective approaches are presented, one tracking the evolution\nof the \\emph{local} TNE effects and the other focussing on the evolution of the\nmean temperature of the fluid, to track the complex interfaces separating the\nbubble and the spike regions of the flow. It is found that, both the\ncompressibility effects and the \\emph{global} TNE intensity show opposite\ntrends in the initial and the later stages of the RTI. Compressibility delays\nthe initial stage of RTI and accelerates the later stage. Meanwhile, the TNE\ncharacteristics are generally enhanced by the compressibility, especially in\nthe later stage. The global or mean thermodynamic non-equilibrium indicators\nprovide physical criteria to discriminate between the two stages of the RTI."
    },
    {
        "anchor": "Shock waves in two-dimensional granular flow: effects of rough walls and\n  polydispersity: We have studied the two-dimensional flow of balls in a small angle funnel,\nwhen either the side walls are rough or the balls are polydisperse. As in\nearlier work on monodisperse flows in smooth funnels, we observe the formation\nof kinematic shock waves/density waves. We find that for rough walls the flows\nare more disordered than for smooth walls and that shock waves generally\npropagate more slowly. For rough wall funnel flow, we show that the shock\nvelocity and frequency obey simple scaling laws. These scaling laws are\nconsistent with those found for smooth wall flow, but here they are cleaner\nsince there are fewer packing-site effects and we study a wider range of\nparameters. For pipe flow (parallel side walls), rough walls support many shock\nwaves, while smooth walls exhibit fewer or no shock waves. For funnel flows of\nballs with varying sizes, we find that flows with weak polydispersity behave\nqualitatively similar to monodisperse flows. For strong polydispersity, scaling\nbreaks down and the shock waves consist of extended areas where the funnel is\nblocked completely.",
        "positive": "Flow states and transitions of an active nematic in a three dimensional\n  channel: We use active nematohydrodynamics to study the flow of an active fluid in a\n3D microchannel, finding a transition between active turbulence and regimes\nwhere there is a net flow along the channel. We show that the net flow is only\npossible if the active nematic is flow aligning and that - in agreement with\nexperiments - the appearance of the net flow depends on the aspect ratio of the\nchannel cross-section. We explain our results in terms of the when hydrodynamic\nscreening due to the channel walls allows the emergence of vortex rolls across\nthe channel."
    },
    {
        "anchor": "Nonequilibrium dynamics of polymer translocation: a mean-field model: We analyse the dynamics of polymer translocation in the strong force regime\nby recasting the problem into solving a differential equation with a moving\nabsorbing boundary. For the total translocation time, $\\tau_{\\rm tr}$, our\nsimple mean-field model predicts that $\\tau_{\\rm tr}\\sim$ (number of\nmonomers)$^{1.5}$, which is in agreement with the exponent found in previous\nsimulation results. Our model also predicts intricate dependencies of\n$\\tau_{\\rm tr}$ on the variations of the pulling force and of the temperature.",
        "positive": "Dynamics of a network fluid within the liquid-gas coexistence region: Low-density networks of molecules or colloids are formed at low temperatures\nwhen the interparticle interactions are valence limited. Prototypical examples\nare networks of patchy particles, where the limited valence results from highly\ndirectional pairwise interactions. We combine extensive Langevin simulations\nand Wertheim's theory of association to study these networks. We find a\nscale-free (relaxation) dynamics within the liquid-gas coexistence region,\nwhich differs from that usually observed for isotropic particles. While for\nisotropic particles the relaxation dynamics is driven by surface tension\n(coarsening), when the valence is limited, the slow relaxation proceeds through\nthe formation of an intermediate non-equilibrium gel via a geometrical\npercolation transition in the Random Percolation universality class."
    },
    {
        "anchor": "Universal conductivity dependence of pure water polyelectrolyte\n  solutions: In order to understand how live matter functions one needs to understand the\ninteraction between polyelectrolytes. We discover a general dependence of\npolyelectrolyte conductivity valid in at least nine decades of polyelectrolyte\nconcentration spanning dilute and semidilute pure water solutions. Furthermore,\nwe showed that current state of the art theories can not explain\npolyelectrolyte conductivity and suggest the path in transport theories which\nneeds to be taken in order to explain polyelectrolyte conductivity.",
        "positive": "Gelation as arrested phase separation in short-ranged attractive\n  colloid-polymer mixtures: We present further evidence that gelation is an arrested phase separation in\nattractive colloid-polymer mixtures, based on a method combining confocal\nmicroscopy experiments with numerical simulations recently established in {\\bf\nNature 453, 499 (2008)}. Our results are independent of the form of the\ninterparticle attractive potential, and therefore should apply broadly to any\nattractive particle system with short-ranged, isotropic attractions. We also\ngive additional characterization of the gel states in terms of their structure,\ninhomogeneous character and local density."
    },
    {
        "anchor": "Asymmetric pattern formation in microswimmer suspensions induced by\n  orienting fields: This paper studies the influence of orienting external fields on pattern\nformation, particularly mesoscale turbulence, in microswimmer suspensions. To\nthis end, we apply a hydrodynamic theory that can be derived from a microscopic\nmicroswimmer model [Phys. Rev. E 97, 022613 (2018)]. The theory combines a\ndynamic equation for the polar order parameter with a modified Stokes equation\nfor the solvent flow. Here, we extend the model by including an external field\nthat exerts an aligning torque on the swimmers (mimicking the situation in\nchemo-, photo-, magneto- or gravitaxis). Compared to the field-free case, the\nexternal field breaks the rotational symmetry of the vortex dynamics and leads\ninstead to strongly asymmetric, traveling stripe patterns, as demonstrated by\nnumerical solution and linear stability analysis. We further analyze the\nemerging structures using a reduced model which involves only an (effective)\nmicroswimmer velocity field. This model is significantly easier to handle\nanalytically, but still preserves the main features of the asymmetric pattern\nformation. We observe an underlying transition between a square vortex lattice\nand a traveling stripe pattern. These structures can be well described in the\nframework of weakly nonlinear analysis, provided the strength of nonlinear\nadvection is sufficiently weak.",
        "positive": "Velocity distribution of a homogeneously driven two-dimensional granular\n  gas: The theory of homogeneously driven granular gases of hard particles predicts\nthat the stationary state is characterized by a velocity distribution function\nwith overpopulated high-energy tails as compared to the exponential decay valid\nfor molecular gases. While this fundamental theoretical result was confirmed by\nnumerous numerical simulations, an experimental confirmation is still missing.\nUsing self-rotating active granular particles, we find a power-law decay of the\nvelocity distribution whose exponent agrees well with the theoretic prediction."
    },
    {
        "anchor": "Bubble statistics and coarsening dynamics for quasi-two dimensional\n  foams with increasing liquid content: We report on the statistics of bubble size, topology, and shape and on their\nrole in the coarsening dynamics for foams consisting of bubbles compressed\nbetween two parallel plates. The design of the sample cell permits control of\nthe liquid content, through a constant pressure condition set by the height of\nthe foam above a liquid reservoir. We find that in the scaling state, all\nbubble distributions are independent not only of time but also of liquid\ncontent. For coarsening, the average rate decreases with liquid content due to\nthe blocking of gas diffusion by Plateau borders inflated with liquid. By\nobserving the growth rate of individual bubbles, we find that von Neumann's law\nbecomes progressively violated with increasing wetness and with decreasing\nbubble size. We successfully model this behavior by explicitly incorporating\nthe border blocking effect into the von Neumann argument. Two dimensionless\nbubble shape parameters naturally arise, one of which is primarily responsible\nfor the violation of von Neumann's law for foams that are not perfectly dry.",
        "positive": "Can pulling cause right- to left-handed structural transitions in\n  negatively supercoiled DNA double-helix?: The folding angle distribution of stretched and negatively supercoiled DNA\ndouble-helix is investigated based on a theoretical model we proposed earlier\n[H. Zhou et al., Phys. Rev. Lett. 82, 4560 (1999)]. It is shown that pulling\ncan transit a negatively supercoiled DNA double-helix from the right-handed\nB-form to a left-handed configuration which resembles DNA Z-form in some\nimportant respects. The energetics of this possible transition is calculated\nand the comparison with recent experimental observations are qualitatively\ndiscussed."
    },
    {
        "anchor": "Critical force in active microrheology: Soft solids like colloidal glasses exhibit a yield stress, above which the\nsystem starts to flow. The microscopic analogon in microrheology is the\ndelocalization of a tracer particle subject to an external force exceeding a\nthreshold value, in a glassy host. We characterize this delocalization\ntransition based on a bifurcation analysis of the corresponding mode-coupling\ntheory equations. A schematic model is presented first, that allows analytical\nprogress, and the full physical model is studied numerically next. This\nanalysis yields a continuous type A transition with a critical power law decay\nof the probe correlation functions with exponent $-1/2$. In order to compare\nwith simulations with a limited duration, a finite time analysis is performed,\nwhich yields reasonable results for not-too-small wave vectors. The\ntheoretically predicted findings are verified by Langevin dynamics simulations.\nFor small wave vectors we find anomalous behavior for the probe position\ncorrelation function, which can be traced back to a wave vector divergence of\nthe critical amplitude. In addition we propose and test three methods to\nextract the critical force from experimental data, which provide the same value\nof the critical force when applied to the finite-time theory or simulations.",
        "positive": "A closer look at arrested spinodal decomposition in protein solutions: Concentrated aqueous solutions of the protein lysozyme undergo a liquid solid\ntransition upon a temperature quench into the unstable spinodal region below a\ncharacteristic arrest temperature of Tf=15C. We use video microscopy and\nultra-small angle light scattering in order to investigate the arrested\nstructures as a function of initial concentration, quench temperature and rate\nof the temperature quench. We find that the solid-like samples show all the\nfeatures of a bicontinuous network that is formed through an arrested spinodal\ndecomposition process. We determine the correlation length Xi and demonstrate\nthat Xi exhibits a temperature dependence that closely follows the critical\nscaling expected for density fluctuations during the early stages of spinodal\ndecomposition. These findings are in agreement with an arrest scenario based on\na state diagram where the arrest or gel line extends far into the unstable\nregion below the spinodal line. Arrest then occurs when during the early stage\nof spinodal decomposition the volume fraction phi2 of the dense phase\nintersects the dynamical arrest threshold phi2Glass, upon which phase\nseparation gets pinned into a space-spanning gel network with a characteristic\nlength Xi."
    },
    {
        "anchor": "Heating anomaly of cold interfacial water under irradiation of\n  mid-infrared pulses: The mid-infrared heating of interfacial water with different initial\ntemperatures is studied using non-equilibrium molecular dynamics simulation. It\nis found that under the irradiation of a pulse at 3360-3380 $cm^{-1}$ the\ntwo-dimensional water monolayer on a hydrophilic surface at a lower initial\ntemperature acquires a much larger temperature jump. The mechanism beneath this\ncounterintuitive phenomenon is the enhanced transition efficiency of the\nasymmetric OH stretching vibration due to the specific oriented configuration\nof water molecules at lower initial temperatures. The understanding of the\nanomalous phenomenon clarifies the sensitivity of the interfacial properties of\nwater molecules to the temperature.",
        "positive": "Dispersion and Orientation patterns in nanorod-infused polymer melts: Introducing nanorods into a polymeric matrix can enhance the physical and\nmechanical properties of the resulting material. In this paper, we focus on\nunderstanding the dispersion and orientation patterns of nanorods in an\nunentangled polymer melt, particularly as a function of nanorod concentration,\nusing Molecular Dynamics (MD) simulations. The system is comprised of flexible\npolymer chains and multi-thread nanorods that are equilibrated in the NPT\nensemble. All interactions are purely repulsive except for those between\npolymers and rods. Results with attractive versus repulsive polymer-rod\ninteractions are compared and contrasted. The concentration of rods has a\ndirect impact on the phase behaviour of the system. At lower concentrations\nrods phase separate into nematic clusters, while at higher concentrations more\nisotropic and less structured rod configurations are observed. A detailed\nexamination of the conformation of the polymer chains near the rod surface\nshows extension of the chains along the director of the rods (especially within\nclusters). The dispersion and orientation of the nanorods is a result of the\ncompetition between depletion entropic forces responsible for the formation of\nrod clusters, the enthalpic effects that improve mixing of rods and polymer,\nand entropic losses of polymers interpenetrating rod clusters."
    },
    {
        "anchor": "Biofilm self-patterning: mechanical forces drive a reorientation cascade: In growing active matter systems, a large collection of engineered or living\nautonomous units metabolize free energy and create order at different length\nscales as they proliferate and migrate collectively. One such example is\nbacterial biofilms, which are surface-attached aggregates of bacterial cells\nembedded in an extracellular matrix. However, how bacterial growth coordinates\nwith cell-surface interactions to create distinctive, long-range order in\nbiofilms remains elusive. Here we report a collective cell reorientation\ncascade in growing Vibrio cholerae biofilms, leading to a differentially\nordered, spatiotemporally coupled core-rim structure reminiscent of a blooming\naster. Cell verticalization in the core generates differential growth that\ndrives radial alignment of the cells in the rim, while the radially aligned rim\nin turn generates compressive stresses that expand the verticalized core. Such\nself-patterning disappears in adhesion-less mutants but can be restored through\nopto-manipulation of growth. Agent-based simulations and two-phase active\nnematic modeling reveal the strong interdependence of the driving forces for\nthe differential ordering. Our findings provide insight into the collective\ncell patterning in bacterial communities and engineering of phenotypes and\nfunctions of living active matter.",
        "positive": "Frequency dependent visco-elastic properties of a water nanomeniscus :\n  an AFM study in Force Feedback Mode: Recently, using an Atomic Force Microscope and a single cantilever excited at\ndifferent frequencies it was shown that water nanomeniscus can exhibit a\ntransition in mechanical responses when submitted to stimuli above few tens of\nkHz. The use of a single cantilever to explore phenomena at frequencies far\nfrom the cantilever resonance frequency is not a common and well-established\nstrategy, and because water meniscus are ubiquitous in nature, we have also\nstudied the water meniscus mechanical response, the stiffness G' (N/m) and the\ndissipation G\"(kg/s), as a function of frequency by using cantilevers with\ndifferent resonance frequencies. These results, based on classic dynamical AFM\ntechnics, confirm the anomalous mechanical response of water nanomeniscus when\nstimulated at frequencies high enough."
    },
    {
        "anchor": "Fingering instability in spreading epithelial monolayers: roles of cell\n  polarisation, substrate friction and contractile stresses: Collective cell migration plays a crucial role in many developmental\nprocesses that underlie morphogenesis, wound healing, or cancer progression. In\nsuch coordinated behaviours, cells are organised in coherent structures and\nactively migrate to serve different biological purposes. In some contexts,\nnamely during epithelial wound healing, it is well known that a migrating\nfree-edge monolayer develops finger-like instabilities, yet the onset is still\nunder debate. Here, by means of theory and numerical simulations, we shed light\non the main mechanisms driving the instability process, analysing the linear\nand nonlinear dynamics of a continuum compressible polar fluid. In particular,\nwe assess the role of cell polarisation, substrate friction, and contractile\nstresses. Linear theory shows that it is crucial to analyse the perturbation\ntransient dynamics, since we unravel a plethora of crossovers between different\nexponential growth rates during the linear regime. Numerical simulations\nsuggest that cell-substrate friction could be the mechanism responsible for the\nformation of complex finger-like structures at the edge, since it triggers\nsecondary fingering instabilities and tip-splitting phenomena. Finally, we\nobtain a critical contractile stress that depends on cell-substrate friction\nand the initial-to-nematic length ratio, characterising an active\nwetting-dewetting transition. In the dewetting scenario, the monolayer retracts\nand becomes stable without developing finger-like structures.",
        "positive": "Localized elasticity governs the nonlinear rheology of colloidal\n  supercooled liquids: We propose a microscopic picture for understanding the nonlinear rheology of\nsupercooled liquids with soft-repulsive potentials. Based on Brownian dynamics\nsimulations of supercooled charge-stabilized colloidal suspensions, our\nanalysis shows that the shear thinning of viscosity (eta) at large enough shear\nrates (sr), expressed as eta~sr^(-lambda), originates from the evolution of the\nlocalized elastic region (LER). An LER is a transient region composed of the\nfirst several coordination shells of a reference particle. In response to the\nexternal shear, particles within LER undergo nearly affine displacement before\nthe yielding of LER. The characteristic strain (gamma) and size (xi) of LER\nrespectively depend on the shear rate by gamma~sr^epsilon and xi~sr^(-nu).\nThree exponents, lambda, epsilon, and nu, are related by lambda=1-epsilon=4*nu.\nThis simple relation connects the nonlinear rheology to the elastic properties\nand the microscopic configurational distortion of the system. The relaxation of\nthe LER is promoted by the large-step nonaffine particle displacement along the\nextensional direction of the shear geometry with the step length of 0.4\nparticle diameter. The elastic deformation and the relaxation of the LER are\nubiquitous and succesive in the flow, which compose the fundamental process\ngoverning the bulk nonlinear viscoelasticity. We apply this model to analyze\nthe Rheo-Small Angle Neutron Scattering data of sheared charge-stabilized\ncolloidal suspensions. It is seen that our model well explains the neutron\nspectra and the rheological data."
    },
    {
        "anchor": "Studying the Kinetics of a Self-propelled Cruiser in 2D Granular Media\n  under Gravity: We propose a cruiser able to move in a granular medium made of nearly 50-50\nbidisperse dissipative particles under gravity. The cruiser has a circular\nshape with a square indentation on its edge. By shifting and then ejecting\ngranular particles entering its indent-region facing a given direction, the\ncruiser gains thrust to push itself forward in the same direction, which can be\neither perpendicular or parallel to gravity. Using molecular dynamics (MD)\nsimulations, we identify three universal phases during one particle-ejection\nprocess: 1) acceleration by the ejection thrust, 2) deceleration by the\ncompressed particles ahead and 3) relaxation with the decompressed particles.\nWe also confirm that the cruising capability improves with increasing the\nparticle-ejection strength and with decreasing the interference from gravity.",
        "positive": "Ab initio correlation effects on the electronic and transport properties\n  of metal(II)-phthalocyanine based devices: Using first principles calculations in the framework of Density Functional\nTheory, we investigated the electronic and transport properties of\nmetal(II)-phthalocyanine (M(II)Pc) systems, both in a single molecule\nconfiguration and in a model-device geometry. In particular, using the\nCopper(II)- and Manganese(II)-Pc as prototypical examples, we studied how\nelectronic correlations on the central metal-ion influence the analysis of the\nelectronic structure of the system and we demonstrated that the choice of the\nexchange-correlation functional, also beyond the standard local or gradient\ncorrected level, is of crucial importance for a correct interpretation of the\ndata. Finally, our electronic transport simulations have shown that\nM(II)Pc-based devices can act selectively as molecular conductors, as in the\ncase of Copper, or as spin valves, as in the case of Manganese, demonstrating\nonce more the great potential of these systems for molecular nanoelectronics\napplications."
    },
    {
        "anchor": "Local structure and dynamics in colloidal fluids and gels: Gels in soft-matter systems are an important nonergodic state of matter. We\nstudy a colloid-polymer mixture which is quenched by increasing the polymer\nconcentration, from a fluid to a gel. Using confocal microscopy, we study both\nthe static structure and dynamics in three dimensions (3D). Between the\ndynamically arrested gel and ergodic fluid comprised of isolated particles we\nfind an intermediate 'cluster fluid' state, where the 'bonds' between the\ncolloidal particles have a finite lifetime. The local dynamics are reminiscent\nof a fluid, while the local structure is almost identical to that of the gel.\nSimultaneous real-time local structural analysis and particle tracking in 3D at\nthe single-particle level yields the following interesting information.\nParticles in the clusters move in a highly correlated manner, but, at the same\ntime, exhibit significant dynamical heterogeneity, reflecting the enhanced\nmobility near the free surface. Deeper quenching eventually leads to a gel\nstate where the 'bond' lifetime exceeds that of the experiment, although the\nlocal structure is almost identical to that of the 'cluster fluid'.",
        "positive": "Inertial Coupling Method for particles in an incompressible fluctuating\n  fluid: We develop an inertial coupling method for modeling the dynamics of\npoint-like 'blob' particles immersed in an incompressible fluid, generalizing\nprevious work for compressible fluids. The coupling consistently includes\nexcess (positive or negative) inertia of the particles relative to the\ndisplaced fluid, and accounts for thermal fluctuations in the fluid momentum\nequation. The coupling between the fluid and the blob is based on a no-slip\nconstraint equating the particle velocity with the local average of the fluid\nvelocity, and conserves momentum and energy. We demonstrate that the\nformulation obeys a fluctuation-dissipation balance, owing to the\nnon-dissipative nature of the no-slip coupling. We develop a spatio-temporal\ndiscretization that preserves, as best as possible, these properties of the\ncontinuum formulation. In the spatial discretization, the local averaging and\nspreading operations are accomplished using compact kernels commonly used in\nimmersed boundary methods. We find that the special properties of these kernels\nmake the discrete blob a particle with surprisingly physically-consistent\nvolume, mass, and hydrodynamic properties. We develop a second-order\nsemi-implicit temporal integrator that maintains discrete\nfluctuation-dissipation balance, and is not limited in stability by viscosity.\nFurthermore, the temporal scheme requires only constant-coefficient Poisson and\nHelmholtz linear solvers, enabling a very efficient and simple FFT-based\nimplementation on GPUs. We numerically investigate the performance of the\nmethod on several standard test problems..."
    },
    {
        "anchor": "Symmetry-breaking in clogging for oppositely driven particles: The clogging behavior of a symmetric binary mixture of particles that are\ndriven in opposite directions through constrictions is explored by Brownian\ndynamics simulations and theory. A dynamical state with a spontaneously broken\nsymmetry occurs where one species is flowing and the other is blocked for a\nlong time which can be tailored by the size of the constrictions. Moreover, we\nfind self-organized oscillations in clogging and unclogging of the two species.\nApart from statistical physics, our results are of relevance for fields like\nbiology, chemistry, and crowd management, where ions, microparticles,\npedestrians, or other particles are driven in opposite directions through\nconstrictions.",
        "positive": "Dynamics of a polymer chain confined in a membrane: We present a Brownian dynamics theory with full hydrodynamics (Stokesian\ndynamics) for a Gaussian polymer chain embedded in a liquid membrane which is\nsurrounded by bulk solvent and walls. The mobility tensors are derived in\nFourier space for the two geometries, namely, a free membrane embedded in a\nbulk fluid, and a membrane sandwiched by the two walls. Within the preaveraging\napproximation, a new expression for the diffusion coefficient of the polymer is\nobtained for the free membrane geometry. We also carry out a Rouse normal mode\nanalysis to obtain the relaxation time and the dynamical structure factor. For\nlarge polymer size, both quantities show Zimm-like behavior in the free\nmembrane case, whereas they are Rouse-like for the sandwiched membrane\ngeometry. We use the scaling argument to discuss the effect of excluded volume\ninteractions on the polymer relaxation time."
    },
    {
        "anchor": "Dynamic Self-Consistent Field Theory for Unentangled Homopolymer Fluids: We present a lattice formulation of a dynamic self-consistent field (DSCF)\ntheory that is capable of resolving interfacial structure, dynamics and\nrheology in inhomogeneous, compressible melts and blends of unentangled\nhomopolymer chains. The joint probability distribution of all the Kuhn segments\nin the fluid, interacting with adjacent segments and walls, is approximated by\na product of one-body probabilities for free segments interacting solely with\nan external potential field that is determined self-consistently. The effect of\nflow on ideal chain conformations is modeled with FENE-P dumbbells, and related\nto stepping probabilities in a random walk. Free segment and stepping\nprobabilities generate statistical weights for chain conformations in a\nself-consistent field, and determine local volume fractions of chain segments.\nFlux balance across unit lattice cells yields mean-field transport equations\nfor the evolution of free segment probabilities and of momentum densities on\nthe Kuhn length scale. Diffusive and viscous contributions to the fluxes arise\nfrom segmental hops modeled as a Markov process, with transition rates\nreflecting changes in segmental interaction, kinetic energy, and entropic\ncontributions to the free energy under flow.",
        "positive": "Anisotropic pseudo-potential for polarized dilute quantum gases: Anisotropic pseudopotential relevant to collisions of two particles polarized\nby external field is rigorously derived and its properties are investigated.\nSuch low-energy pseudopotential may be useful in describing collective\nproperties of dilute quantum gases, such as molecules polarized by electric\nfield or metastable $^3P_2$ atoms polarized by magnetic field. The\npseudopotential is expressed in terms of reactance (K--) matrix and derivatives\nof Dirac delta-function. In most applications it may be represented as a sum of\ntraditional spherically-symmetric contact term and anisotropic part. The former\ncontribution may be parameterized by a generalized scattering length. The\nanisotropic part of pseudopotential may be characterized by off-diagonal\nscattering length for dipolar interactions and off-diagonal scattering volume\nfor quadrupolar interactions. Two-body matrix element of the pseudopotential in\na basis of plane waves is also derived."
    },
    {
        "anchor": "Microscopic insights into the failure of elastic double networks: The toughness of a polymer material can increase significantly if two\nnetworks are combined into one material. This toughening effect is a\nconsequence of a transition from a brittle to a ductile failure response.\nAlthough this transition and the accompanying toughening effect have been\ndemonstrated in hydrogels first, the concept has been proven effective in\nelastomers and in macroscopic composites as well. This suggests that the\ntransition is not caused by a specific molecular architecture, but rather by a\ngeneral physical principle related to the mechanical interplay between two\ninterpenetrating networks. Here we employ theory and computer simulations,\ninspired by this general principle, to investigate how disorder controls the\nbrittle-to-ductile transition both at the macroscopic and the microscopic\nlevel. A random spring network model featuring two different spring types,\nenables us to study the joined effect of initial disorder and network-induced\nstress heterogeneity on this transition. We reveal that a mechanical force\nbalance gives a good description of the brittle-to-ductile transition. In\naddition, the inclusion of disorder in the spring model predicts four different\nfailure regimes along the brittle-to-ductile response in agreement with\nexperimental findings. Finally, we show that the network structure can result\nin stress concentration, diffuse damage and loss of percolation depending on\nthe failure regime. This work thus provides a framework for the design and\noptimization of double network materials and underlines the importance of\nnetwork structure in the toughness of polymer materials.",
        "positive": "Field driven cluster formation in two-dimensional colloidal binary\n  mixtures: We study size- and charge-asymmetric oppositely charged colloids driven by an\nexternal electric field. The large particles are connected by harmonic springs,\nforming a hexagonal-lattice network while the small particles are free of bonds\nand exhibit fluid-like motion. We show that this model exhibits a cluster\nformation pattern when the external driving force exceeds a critical value. The\nclustering is accompanied with stable wavepackets in vibrational motions of the\nlarge particles."
    },
    {
        "anchor": "Instabilities and diffusion in a hydrodynamic model of a fluid membrane\n  coupled to a thin active fluid layer: We construct a coarse-grained effective two-dimensional (2d) hydrodynamic\ntheory as a theoretical model for a coupled system of a fluid membrane and a\nthin layer of a polar active fluid in its ordered state that is anchored to the\nmembrane. We show that such a system is prone to generic instabilities through\nthe interplay of nonequilibrium drive, polar order and membrane fluctuation. We\nuse our model equations to calculate diffusion coefficients of an inclusion in\nthe membrane and show that their values depend strongly on the system size, in\ncontrast to their equilibrium values. Our work extends the work of S.\nSankararaman and S. Ramaswamy [Phys. Rev. Lett., 102, 118107 (2009)] to a\ncoupled system of a fluid membrane and an ordered active fluid layer. Our model\nis broadly inspired by and should be useful as a starting point for theoretical\ndescriptions of the coupled dynamics of a cell membrane and a cortical actin\nlayer anchored to it.",
        "positive": "Nonmonotonic Aging and Memory Retention in Disordered Mechanical Systems: We observe non-monotonic aging and memory effects, two hallmarks of glassy\ndynamics, in two disordered mechanical systems: crumpled thin sheets and\nelastic foams. Under fixed compression, both systems exhibit monotonic\nnon-exponential relaxation. However, when after a certain waiting time the\ncompression is partially reduced, both systems exhibit a non-monotonic\nresponse: the normal force first increases over many minutes or even hours\nuntil reaching a peak value, and only then relaxation is resumed. The peak-time\nscales linearly with the waiting time, indicating that these systems retain\nlong-lasting memory of previous conditions. Our results and the measured\nscaling relations are in good agreement with a theoretical model recently used\nto describe observations of monotonic aging in several glassy systems,\nsuggesting that the non-monotonic behavior may be generic and that a-thermal\nsystems can show genuine glassy behavior."
    },
    {
        "anchor": "Biopolymer filtration in corrugated nanochannels: We examine pressure-driven non-equilibrium transport of linear, circular and\nstar polymers through a nanochannel containing a rectangular pit with full\nhydrodynamic interactions and thermal fluctuations. We demonstrate that with\nsufficiently small pressure differences, there is contour length-dependent\nentropic trapping of the polymer in the pit when the pit and the polymer sizes\nare compatible. This is due to competition between flow and chain relaxation in\nthe pit, which leads to a non-monotonic dependence of the polymer mobility on\nits size and should aid in the design of nanofiltration devices based on the\npolymer size and shape.",
        "positive": "Effective medium theory of conduction in stretched polymer electrolytes: Recent experimental observations of anisotropic conductivity in stretched\npolymer electrolytes films of the polyethylene oxide family are discussed. The\nmain experimental observations, enhancement of the ionic diffusion and\nconductivity in the stretch direction and decrease in these transport\ncoefficients in the normal direction are interpreted in terms of an effective\ntwo-phase model. This two-phase model is based on the idea that a highly\nconducting phase is associated with oriented molecular structures which are\nsurrounded by poorly conducting boundary regions. This model is evaluated\nwithin the framework of differential effective medium theory (DEMT). Under\nstretching these regions change from spherical to prolate-spheroidal shapes.\nThe computed dependence of the DC conductivity tensor and its AC counterpart on\nthe stretch parameters is in good agreement with experimental results."
    },
    {
        "anchor": "Local Cooperativity Mechanism in the DNA Melting Transition: We propose a new statistical mechanics model for the melting transition of\nDNA. Base pairing and stacking are treated as separate degrees of freedom, and\nthe interplay between pairing and stacking is described by a set of local rules\nwhich mimic the geometrical constraints in the real molecule. This microscopic\nmechanism intrinsically accounts for the cooperativity related to the free\nenergy penalty of bubble nucleation. The model describes both the unpairing and\nunstacking parts of the spectroscopically determined experimental melting\ncurves. Furthermore, the model explains the observed temperature dependence of\nthe effective thermodynamic parameters used in models of the nearest neighbor\n(NN) type. We compute the partition function for the model through the transfer\nmatrix formalism, which we also generalize to include non local chain entropy\nterms. This part introduces a new parametrization of the Yeramian-like transfer\nmatrix approach to the Poland-Scheraga description of DNA melting. The model is\nexactly solvable in the homogeneous thermodynamic limit, and we calculate all\nobservables without use of the grand partition function. As is well known,\nmodels of this class have a first order or continuous phase transition at the\ntemperature of complete strand separation depending on the value of the\nexponent of the bubble entropy.",
        "positive": "The structural, vibrational, and mechanical properties of jammed\n  packings of deformable particles in three dimensions: We investigate the structural, vibrational, and mechanical properties of\njammed packings of deformable particles with shape degrees of freedom in three\ndimensions (3D). Each 3D deformable particle is modeled as a\nsurface-triangulated polyhedron, with spherical vertices whose positions are\ndetermined by a shape-energy function with terms that constrain the particle\nsurface area, volume, and curvature, and prevent interparticle overlap. We show\nthat jammed packings of deformable particles without bending energy possess\nlow-frequency, quartic vibrational modes, whose number decreases with\nincreasing asphericity and matches the number of missing contacts relative to\nthe isostatic value. In contrast, jammed packings of deformable particles with\nnon-zero bending energy are isostatic in 3D, with no quartic modes. We find\nthat the contributions to the eigenmodes of the dynamical matrix from the shape\ndegrees of freedom are significant over the full range of frequency and shape\nparameters for particles with zero bending energy. We further show that the\nensemble-averaged shear modulus $\\langle G \\rangle$ scales with pressure $P$ as\n$\\langle G \\rangle \\sim P^{\\beta}$, with $\\beta \\approx 0.75$ for jammed\npackings of deformable particles with zero bending energy. In contrast, $\\beta\n\\approx 0.5$ for packings of deformable particles with non-zero bending energy,\nwhich matches the value for jammed packings of soft, spherical particles with\nfixed shape. These studies underscore the importance of incorporating particle\ndeformability and shape change when modeling the properties of jammed soft\nmaterials."
    },
    {
        "anchor": "Nonaffine rearrangements of atoms in deformed and quiescent binary\n  glasses: The influence of periodic shear deformation on nonaffine atomic displacements\nin an amorphous solid is examined via molecular dynamics simulations. We study\nthe three-dimensional Kob-Andersen binary mixture model at a finite\ntemperature. It is found that when the material is periodically strained, most\nof the atoms undergo repetitive nonaffine displacements with amplitudes that\nare broadly distributed. We show that particles with large amplitudes of\nnonaffine displacements are organized into compact clusters. With increasing\nstrain amplitude, spatial correlations of nonaffine displacements become\nincreasingly long-ranged, although they remain present even in a quiescent\nsystem due to thermal fluctuations.",
        "positive": "Interaction of surfactant and protein at the o/w interface and its\n  effect on colloidal and biological properties of polymeric nanocarriers: The use of polymer-based surfactants in the double-emulsion (water/oil/water,\nW/O/W) solvent-evaporation technique is becoming a widespread strategy for\npreparing biocompatible and biodegradable polymeric nanoparticles (NPs) loaded\nwith biomolecules of interest in biomedicine, or biotechnology. This approach\nenhances the stability of the NPs, reduces their size and recognition by the\nmononuclear phagocytic system, and protects the encapsulated biomolecule\nagainst losing biological activity. Different protocols to add the surfactant\nduring the synthesis lead to different NP colloidal properties and biological\nactivity."
    },
    {
        "anchor": "Role of particle conservation in self-propelled particle systems: Actively propelled particles undergoing dissipative collisions are known to\ndevelop a state of spatially distributed coherently moving clusters. For\ndensities larger than a characteristic value clusters grow in time and form a\nstationary well-ordered state of coherent macroscopic motion. In this work we\naddress two questions: (i) What is the role of the particles' aspect ratio in\nthe context of cluster formation, and does the particle shape affect the\nsystem's behavior on hydrodynamic scales? (ii) To what extent does particle\nconservation influence pattern formation? To answer these questions we suggest\na simple kinetic model permitting to depict some of the interaction properties\nbetween freely moving particles and particles integrated in clusters. To this\nend, we introduce two particle species: single and cluster particles.\nSpecifically, we account for coalescence of clusters from single particles,\nassembly of single particles on existing clusters, collisions between clusters,\nand cluster disassembly. Coarse-graining our kinetic model, (i) we demonstrate\nthat particle shape (i.e. aspect ratio) shifts the scale of the transition\ndensity, but does not impact the instabilities at the ordering threshold. (ii)\nWe show that the validity of particle conservation determines the existence of\na longitudinal instability, which tends to amplify density heterogeneities\nlocally, and in turn triggers a wave pattern with wave vectors parallel to the\naxis of macroscopic order. If the system is in contact with a particle\nreservoir this instability vanishes due to a compensation of density\nheterogeneities.",
        "positive": "Filtration method characterizing the reversibility of colloidal fouling\n  layers at a membrane surface: analysis through critical flux and osmotic\n  pressure: A filtration procedure was developed to measure the reversibility of fouling\nduring cross-flow filtration based on the square wave of applied pressure. The\nprinciple of this method, the apparatus required, and the associated\nmathematical relationships are detailed. This method allows for differentiating\nthe reversible accumulation of matter on, and the irreversible fouling of, a\nmembrane surface. Distinguishing these two forms of attachment to a membrane\nsurface provides a means by which the critical flux may be determined. To\nvalidate this method, experiments were performed with a latex suspension at\ndifferent degrees of destabilization (obtained by the addition of salt to the\nsuspension) and at different cross-flow velocities. The dependence of the\ncritical flux on these conditions is discussed and analysed through the osmotic\npressure of the colloidal dispersion."
    },
    {
        "anchor": "On stickiness of multiscale randomly rough surfaces: We derive a very simple and effective stickiness criterion for solids having\nrandom roughness using a new asymptotic theory, which we validate with that of\nPersson and Scaraggi and independent numerical experiments. Previous claims\nthat stickiness may depend on small scale quantities such as rms slopes and/or\ncurvatures, obtained by making oversimplified assumptions on the contact area\ngeometry, are largely incorrect, as the truncation of the PSD spectrum of\nroughness at short wavelengths is irrelevant. We find stickiness is destroyed\ntypically at roughness amplitudes up to three orders of magnitude larger than\nthe range of attractive forces. With typical nanometer values of the latter,\nthe criterion gives justification to the qualitative well known empirical\nDalhquist criterion for stickiness which demands adhesives to have elastic\nmodulus lower than about 1MPa. The results clarifies a much debated question in\nboth the scientific and technological world of adhesion, and may serve as\nbenchmark for better comprehension of the role of roughness.",
        "positive": "Self-assembled aggregates in the gravitational field: growth and nematic\n  order: The influence of the gravitational field on the reversible process of\nassembly and disassembly of linear aggregates is focus of this paper. Even the\nearth gravitational field can affect the equilibrium properties of heavy\nbiological aggregates such as microtubules or actin filaments. The gravity\ngives rise to the concentration gradient which results in the distribution of\naggregates of different lengths with height. Strong enough gravitational field\ninduces the overall growth of the aggregates. The gravitational field\nfacilitates the isotropic to nematic phase transition reflecting in a broader\ntransition region. Coexisting phases have notedly different length\ndistributions and the phase transition represent the interplay between the\ngrowth in the isotropic phase and the precipitation into nematic phase. The\nfields in an ultracentrifuge can only reinforce the effect of gravity, so the\npresent description can be applied to a wider range of systems."
    },
    {
        "anchor": "Free volume theory explains the unusual behavior of viscosity in a\n  non-confluent tissue during morphogenesis: A recent experiment on zebrafish blastoderm morphogenesis showed that the\nviscosity ({\\eta}) of a non-confluent embryonic tissue grows sharply until a\ncritical cell packing fraction ({\\phi}S). The increase in {\\eta} up to {\\phi}S\nis similar to the behavior observed in several glass-forming materials, which\nsuggests that the cell dynamics is sluggish or glass-like. Surprisingly, {\\eta}\nis a constant above {\\phi}S. To determine the mechanism of this unusual\ndependence of {\\eta} on {\\phi}, we performed extensive simulations using an\nagent-based model of a dense non-confluent two-dimensional tissue. We show that\npolydispersity in the cell size, and the propensity of the cells to deform,\nresults in the saturation of the available free area per cell beyond a critical\npacking fraction. Saturation in the free space not only explains the viscosity\nplateau above {\\phi}S but also provides a relationship between equilibrium\ngeometrical packing to the dramatic increase in the relaxation dynamics.",
        "positive": "How reciprocity impacts ordering and phase separation in active\n  nematics?: Active nematics undergo spontaneous symmetry breaking and show phase\nseparation instability. Within the prevailing notion that macroscopic\nproperties depend only on symmetries and conservation laws, different\nmicroscopic models are used out of convenience. Here, we test this notion\ncarefully by analyzing three different microscopic models of apolar active\nnematics. They share the same symmetry but differ in implementing reciprocal or\nnon-reciprocal interactions, including a Vicsek-like implementation. We show\nhow such subtle differences in microscopic realization determine if the\nordering transition is continuous or first order. Despite the difference in the\ntype of phase transition, all three models exhibit fluctuation-dominated phase\nseparation and quasi-long-range order in the nematic phase."
    },
    {
        "anchor": "Continuum modelling and simulation of granular flows through their many\n  phases: We propose and numerically implement a constitutive framework for granular\nmedia that allows the material to traverse through its many common phases\nduring the flow process. When dense, the material is treated as a pressure\nsensitive elasto-viscoplastic solid obeying a yield criterion and a plastic\nflow rule given by the $\\mu(I)$ inertial rheology of granular materials. When\nthe free volume exceeds a critical level, the material is deemed to separate\nand is treated as disconnected, stress-free media. A Material Point Method\n(MPM) procedure is written for the simulation of this model and many\ndemonstrations are provided in different geometries. By using the MPM\nframework, extremely large strains and nonlinear deformations, which are common\nin granular flows, are representable. The method is verified numerically and\nits physical predictions are validated against known results.",
        "positive": "Coupling of sedimentation and liquid structure: influence on hard sphere\n  nucleation: The discrepancy in nucleation rate densities between simulated and\nexperimental hard spheres remains staggering and unexplained. Suggestively,\nmore strongly sedimenting colloidal suspensions of hard spheres nucleate much\nfaster than weakly sedimenting systems. In this work we consider firstly the\neffect of sedimentation on the structure of colloidal hard spheres, by tuning\nthe density mismatch between solvent and colloidal particles. In particular we\ninvestigate the effect on the degree of five fold symmetry present. Secondly we\nstudy the size of density fluctuations in these experimental systems in\ncomparison to simulations. The density fluctuations are measured by assigning\neach particle a local density, which is related to the number of particles\nwithin a distance of 3.25 particle diameters. The standard deviation of these\nlocal densities gives an indication of the fluctuations present in the system.\nFive fold symmetry is suppressed by a factor of two when sedimentation is\ninduced in our system. Density fluctuations are also increased by a factor of\ntwo in experiments compared to simulations. The change in five fold symmetry\nmakes a difference to the expected nucleation rates, but we demonstrate that it\nis ultimately too small to resolve the discrepancy between experiment and\nsimulation, while the fluctuations are shown to be an artefact of 3d particle\ntracking."
    },
    {
        "anchor": "Modulated Collective Behaviors and Condensation of Bacteria: Bacteria can spontaneously develop collective motions by aligning their\nmotions in dense systems. Here, we show that bacteria can also respond\ncollectively to an alternating electrical field and form dynamic clusters\noscillating at the same frequency of the field. As the dynamic clusters go\nbeyond a critical size, they split into smaller ones spontaneously. The\ncritical size for splitting depends on the frequency of electric field and the\nconcentration of bacteria. We show that instead of their biological activity,\nthe physical properties of bacteria as charged particles are responsible for\nthe formation of dynamic clusters. Electroconvective flows across the system\nplay the key role in stabilizing the clusters. However, to form clusters,\ncollective hydrodynamic cooperation between bacteria is important such that no\naggregation occurs in dilute suspensions. The findings in this study illustrate\nthat bio-systems can respond collectively to an external field, promising an\neffective way to control and modulate the behavior of organisms. Moreover, the\ncontrolled aggregation and condensation of bacteria offer a robust approach to\nimprove the local concentration of bacteria for early and rapid detection,\nwhich has wide applications in clinics.",
        "positive": "Arrested States in Persistent Active Matter: Gelation without Attraction: We explore phase separation and kinetic arrest in a model active colloidal\nsystem consisting of self-propelled, hard-core particles with nonconvex shapes.\nThe passive limit of the model, namely cross-shaped particles on a square\nlattice, exhibits a first-order transition from a fluid phase to a solid phase\nwith increasing density. Quenches into the two-phase coexistence region exhibit\nan aging regime. The nonconvex shape of the particles eases jamming in the\npassive system and leads to strong inhibition of rotations of the active\nparticles. Using numerical simulations and analytical modeling, we quantify the\nnonequilibrium phase behavior as a function of density and activity. If we view\nactivity as the analog of attraction strength, the phase diagram exhibits\nstrong similarities to that of attractive colloids, exhibiting both aging,\nglassy states and gel-like arrested states. The two types of dynamically\narrested states, glasses and gels, are distinguished by the appearance of\ndensity heterogenities in the latter. In the infinitely persistent limit, we\nshow that a coarse-grained model based on the asymmetric exclusion process\nquantitatively predicts the density profiles of the gel states. The predictions\nremain qualitatively valid for finite rotation rates. Using these results, we\nclassify the activity-driven phases and identify the boundaries separating\nthem."
    },
    {
        "anchor": "Suppression of water vapor condensation by glycerol droplets on\n  hydrophobic surfaces: Vapor sink is an effective strategy to suppress the formation of water vapor\ncondensation around hygroscopic materials, and consequently reduce frosting and\nicing. However, traditionally used materials, such as salt solutions, fibers,\nexhibit insufficient condensation inhibition or pose safety concerns, such as\ncorrosiveness. In this study, we highlight the remarkable anti-condensation\nproperties of glycerol droplets, attributed to their strong hygroscopicity. We\ncompared the anti-condensation capabilities of glycerol droplets with commonly\nused salt solutions and hygroscopic alcohols. The results indicated that\nglycerol droplets establish a relatively expansive dry zone where the\ncondensation is effectively inhibited, while also offering safety compared to\nother materials. Furthermore, we conducted a systematic study of the\nanti-condensation properties of glycerol droplets with experiments and\ntheoretical analysis. We explored the varying trends of the dry zone ratio\nconcerning temperature, cooling time, humidity, and droplet volume on\nhydrophobic surfaces. To provide a comprehensive understanding, we propose a\nstraightforward yet robust theoretical model that elucidates the relationship\nbetween this ratio and temperature, aligning well with the experimental data.\nOur study not only sheds light on the superior anti-condensation qualities of\nglycerol but also offers insights and guidelines for the development of\neffective anti-icing and anti-frost materials.",
        "positive": "High Resolution Viscosity Measurement by Thermal Noise Detection: An interferometric method is implemented in order to accurately assess the\nthermal fluctuations of a micro-cantilever sensor in liquid environments. The\npower spectrum density (PSD) of thermal fluctuations together with Sader's\nmodel of the cantilever allow for the indirect measurement of the liquid\nviscosity with good accuracy. The good quality of the deflection signal and the\ncharacteristic low noise of the instrument allow for the detection and\ncorrections of drawbacks due to both the cantilever shape irregularities and\nthe uncertainties on the position of the laser spot at the fluctuating end of\nthe cantilever. Variation of viscosity below 0.03 mPa$\\cdot$s was detected with\nthe alternative to achieve measurements with a volume as low as 50 $\\mu$L."
    },
    {
        "anchor": "Realization of Bose-Einstein condensates in lower dimensions: Bose-Einstein condensates of sodium atoms have been prepared in optical and\nmagnetic traps in which the energy-level spacing in one or two dimensions\nexceeds the interaction energy between atoms, realizing condensates of lower\ndimensionality. The cross-over into two-dimensional and one-dimensional\ncondensates was observed by a change in aspect ratio and saturation of the\nrelease energy when the number of trapped atoms was reduced.",
        "positive": "Three-Dimensional Generalized Dynamics of Soft-Matter Quasicrystals: The three-dimensional generalized dynamics of soft-matter quasicrystals was\ninvestigated, in which the governing equations of the dynamics are derived for\nobserved 12-fold symmetry quasicrystals and possible observed 8- and\n10-symmetry ones in near future in soft matter. The solving methods, possible\nsolutions for some initial and boundary value problems of the equations and\npossible applications are discussed as well."
    },
    {
        "anchor": "Reduced-variance orientational distribution functions from torque\n  sampling: We introduce a method to sample the orientational distribution function in\ncomputer simulations. The method is based on the exact torque balance equation\nfor classical many-body systems of interacting anisotropic particles in\nequilibrium. Instead of the traditional counting of events, we reconstruct the\norientational distribution function via an orientational integral of the torque\nacting on the particles. We test the torque sampling method in two- and\nthree-dimensions, using both Langevin dynamics and overdamped Brownian\ndynamics, and with two interparticle interaction potentials. In all cases the\ntorque sampling method produces profiles of the orientational distribution\nfunction with better accuracy than those obtained with the traditional counting\nmethod. The accuracy of the torque sampling method is independent of the bin\nsize, and hence it is possible to resolve the orientational distribution\nfunction with arbitrarily small angular resolutions.",
        "positive": "Pathways to faceting of vesicles: The interplay between geometry, topology and order can lead to geometric\nfrustration that profoundly affects the shape and structure of a curved\nsurface. In this commentary we show how frustration in this context can result\nin the faceting of elastic vesicles. We show that, under the right conditions,\nan assortment of regular and irregular polyhedral structures may be the low\nenergy states of elastic membranes with spherical topology. In particular, we\nshow how topological defects, necessarily present in any crystalline lattice\nconfined to spherical topology, naturally lead to the formation of icosahedra\nin a homogeneous elastic vesicle. Furthermore, we show that introducing\nheterogeneities in the elastic properties, or allowing for non-linear bending\nresponse of a homogeneous system, opens non-trivial pathways to the formation\nof faceted, yet non-icosahedral, structures."
    },
    {
        "anchor": "The replica method in liquid theory: from the basics to explicit\n  computations: In these notes we introduce briefly the fundamentals of the replica method in\nthe context of liquid theory and the structural glass problem. In particular,\nwe explain and show its usefulness as a computation framework in the context of\nthe Random First Order Transition (RFOT) theory of the glass transition, whose\ndefining points the reader is assumed to know. We shall give the intuitive idea\nof how and why the replica method is suitable for the description of the glass\ntransition (the dynamical glass transition in particular) in real liquids, and\nthen show how it can be used to make explicit computations and predictions that\ncan be compared to experiments and numerical simulations.",
        "positive": "Response of Single Polymers to Localized Step Strains: In this paper, the response of single three-dimensional phantom and\nself-avoiding polymers to localized step strains are studied for two cases in\nthe absence of hydrodynamic interactions: (i) polymers tethered at one end with\nthe strain created at the point of tether, and (ii) free polymers with the\nstrain created in the middle of the polymer. The polymers are assumed to be in\ntheir equilibrium state before the step strain is created. It is shown that the\nstrain relaxes as a power-law in time $t$ as $t^{-\\eta}$. While the strain\nrelaxes as $1/t$ for the phantom polymer in both cases; the self-avoiding\npolymer relaxes its strain differently in case (i) than in case (ii): as\n$t^{-(1+\\nu)/(1+2\\nu)}$ and as $t^{-2/(1+2\\nu)}$ respectively. Here $\\nu$ is\nthe Flory exponent for the polymer, with value $\\approx0.588$ in three\ndimensions. Using the mode expansion method, exact derivations are provided for\nthe $1/t$ strain relaxation behavior for the phantom polymer. However, since\nthe mode expansion method for self-avoiding polymers is nonlinear, similar\ntheoretical derivations for the self-avoiding polymer proves difficult to\nprovide. Only simulation data are therefore presented in support of the\n$t^{-(1+\\nu)/(1+2\\nu)}$ and the $t^{-2/(1+2\\nu)}$ behavior. The relevance of\nthese exponents for the anomalous dynamics of polymers are also discussed."
    },
    {
        "anchor": "Equilibrium organization, conformation, and dynamics of two polymers\n  under box-like confinement: Motivated by recent nanofluidics experiments, we use Brownian dynamics and\nMonte Carlo simulations to study the conformation, organization and dynamics of\ntwo polymer chains confined to a single box-like cavity. The polymers are\nmodeled as flexible hard-sphere chains, and the box has a square cross-section\nof side length $L$ and a height that is small enough to compress the polymers\nin that dimension. For sufficiently large $L$, the system behaviour approaches\nthat of an isolated polymer in a slit. However, the combined effects of\ncrowding and confinement on the polymer organization, conformation and\nequilibrium dynamics become significant when $L/R_{{\\rm g},xy}^*\\lesssim 5$,\nwhere $R_{{\\rm g},xy}^*$ is the transverse radius of gyration for a slit\ngeometry. In this regime, the centre-of-mass probability distribution in the\ntransverse plane exhibits a depletion zone near the centre of the cavity\n(except at very small $L$) and a 4-fold symmetry with quasi-discrete positions.\nReduction in polymer size with decreasing $L$ arises principally from\nconfinement rather than inter-polymer crowding. By contrast, polymer diffusion\nand internal motion are strongly affected by inter-polymer crowding. The two\npolymers tend to occupy opposite positions relative to the box centre, about\nwhich they diffuse relatively freely. Qualitatively, this static and dynamical\nbehaviour differs significantly from that previously observed for confinement\nof two polymers to a narrow channel. The simulation results for a suitably\nchosen box width are qualitatively consistent with results from a recent\nexperimental study of two $\\lambda$-DNA chains confined to a nanofluidic\ncavity.",
        "positive": "Incorporating Cellular Stochasticity in Solid--Fluid Mixture Biofilm\n  Models: The dynamics of cellular aggregates is driven by the interplay of\nmechanochemical processes and cellular activity. Although deterministic models\nmay capture mechanical features, local chemical fluctuations trigger random\ncell responses, which determine the overall evolution. Incorporating stochastic\ncellular behavior in macroscopic models of biological media is a challenging\ntask. Herein, we propose hybrid models for bacterial biofilm growth, which\ncouple a two phase solid/fluid mixture description of mechanical and chemical\nfields with a dynamic energy budget-based cellular automata treatment of\nbacterial activity. Thin film and plate approximations for the relevant\ninterfaces allow us to obtain numerical solutions exhibiting behaviors observed\nin experiments, such as accelerated spread due to water intake from the\nenvironment, wrinkle formation, undulated contour development, and the\nappearance of inhomogeneous distributions of differentiated bacteria performing\nvaried tasks."
    },
    {
        "anchor": "Integration through transients for Brownian particles under steady shear: Starting from the microscopic Smoluchowski equation for interacting Brownian\nparticles under stationary shearing, exact expressions for shear-dependent\nsteady-state averages, correlation and structure functions, and\nsusceptibilities are obtained, which take the form of generalized Green-Kubo\nrelations. They require integration of transient dynamics. Equations of motion\nwith memory effects for transient density fluctuation functions are derived\nfrom the same microscopic starting point. We argue that the derived formal\nexpressions provide useful starting points for approximations in order to\ndescribe the stationary non-equilibrium state of steadily sheared dense\ncolloidal dispersions.",
        "positive": "Paraelectric and ferroelectric order in two-state dipolar fluids: Monte Carlo simulations are used to examine cooperative creation of polar\nstate in fluids of two-state particles with nonzero dipole in the excited\nstate. With lowering temperature such systems undergo a second order transition\nfrom nonpolar to polar, paraelectric phase. The transition is accompanied by a\ndielectric anomaly of polarization susceptibility increasing by three orders of\nmagnitude. The paraelectric phase is then followed by formation of a nematic\nferroelectric which further freezes into an fcc ferroelectric crystal by a\nfirst order transition. A mean-field model of phase transitions is discussed."
    },
    {
        "anchor": "Structure and diffusion of active-passive binary mixtures in a\n  single-file: We numerically study structure and dynamics of single files composed of\nactive particles, as well as, active-passive binary mixtures. Our simulation\nresults show that when the persistent length of self-propelled particles is\nmuch larger than the average inter-particle separation and the self-propulsion\nvelocity is larger than the thermal velocity, particles in the file exist as\nclusters of various sizes. Average cluster size and structures of the file are\nvery sensitive to self-propulsion properties, thermal fluctuations and\ncomposition of the mixture. In addition to the variation of file composition,\nour study considers two sorts of mixture configurations. One corresponds to the\nuniform distribution of active passive throughout the mixture in the single\nfile. In the other configuration, active particles are on one side of the file.\nFor the both configurations, even a little fraction of active particles\nproduces a large impact on the structure and dynamics of the file.",
        "positive": "Oscillating membranes: modeling and controlling autonomous\n  shape-transforming sheets: Living organisms have mastered the dynamic control of internal stresses to\nperform an array of functions, such as change shape and locomote.\nState-of-the-art attempts to replicate this ability in synthetic materials are\nrudimentary in comparison. Here we present the first experimental realization\nof a self-oscillating gel in a thin sheet configuration. We show that internal\nsignaling produces stresses that drive lifelike shape changes, that the\nmaterial's response is accurately modelled with the theory of non-Euclidean\nelasticity and that the internal signaling can be programmed with light.\nTogether, our results demonstrate a complete route for developing fully\nautonomous soft machines."
    },
    {
        "anchor": "How a Vicinal Layer of Solvent Modulates the Dynamics of Proteins: The dynamics of a folded protein is studied in water and glycerol at a series\nof temperatures below and above their respective dynamical transition. The\nsystem is modeled in two distinct states whereby the protein is decoupled from\nthe bulk solvent at low temperatures, and communicates with it through a\nvicinal layer at physiological temperatures. A linear viscoelastic model\nelucidates the less-than-expected increase in the relaxation times observed in\nthe backbone dynamics of the protein. The model further explains the increase\nin the flexibility of the protein once the transition takes place and the\ndifferences in the flexibility under the different solvent environments.\nCoupling between the vicinal layer and the protein fluctuations is necessary to\ninterpret these observations. The vicinal layer is postulated to form once a\nthreshold for the volumetric fluctuations in the protein to accommodate\nsolvents of different sizes is reached. Compensation of entropic-energetic\ncontributions from the protein-coupled vicinal layer quantifies the scaling of\nthe dynamical transition temperatures in various solvents. The protein adapts\ndifferent conformational routes for organizing the required coupling to a\nspecific solvent, which is achieved by adjusting the amount of conformational\njumps in the surface-group dihedrals.",
        "positive": "Quasi-One Dimensional Models for Glassy Dynamics: We describe numerical simulations and analyses of a quasi-one-dimensional\n(Q1D) model of glassy dynamics. In this model, hard rods undergo Brownian\ndynamics through a series of narrow channels connected by $J$ intersections. We\ndo not allow the rods to turn at the intersections, and thus there is a single,\ncontinuous route through the system. This Q1D model displays caging behavior,\ncollective particle rearrangements, and rapid growth of the structural\nrelaxation time, which are also found in supercooled liquids and glasses. The\nmean-square displacement $\\Sigma(t)$ for this Q1D model displays several\ndynamical regimes: 1) short-time diffusion $\\Sigma(t) \\sim t$, 2) a plateau in\nthe mean-square displacement caused by caging behavior, 3) single-file\ndiffusion characterized by anomalous scaling $\\Sigma(t) \\sim t^{0.5}$ at\nintermediate times, and 4) a crossover to long-time diffusion $\\Sigma(t) \\sim\nt$ for times $t$ that grow with the complexity of the circuit. We develop a\ngeneral procedure for determining the structural relaxation time $t_D$, beyond\nwhich the system undergoes long-time diffusion, as a function of the packing\nfraction $\\phi$ and system topology. This procedure involves several steps: 1)\ndefine a set of distinct microstates in configuration space of the system, 2)\nconstruct a directed network of microstates and transitions between them, 3)\nidentify minimal, closed loops in the network that give rise to structural\nrelaxation, 4) determine the frequencies of `bottleneck' microstates that\ncontrol the slow dynamics and time required to transition out of them, and 5)\nuse the microstate frequencies and lifetimes to deduce $t_D(\\phi)$. We find\nthat $t_D$ obeys power-law scaling, $t_D\\sim (\\phi^* - \\phi)^{-\\alpha}$, where\nboth $\\phi^*$ (signaling complete kinetic arrest) and $\\alpha>0$ depend on the\nsystem topology."
    },
    {
        "anchor": "High speed imaging of traveling waves in a granular material during silo\n  discharge: We report experimental observations of sound waves in a granular material\nduring resonant silo discharge called silo music. The grain motion was tracked\nby high speed imaging while the resonance of the silo was detected by\naccelerometers and acoustic methods. The grains do not oscillate in phase at\nneighboring vertical locations, but information propagates upward in this\nsystem in the form of sound waves. We show that the wave velocity is not\nconstant throughout the silo, but considerably increases towards the lower end\nof the system, suggesting increased pressure in this region, where the flow\nchanges from cylindrical to converging flow. In the upper part of the silo the\nwave velocity matches the sound velocity measured in the same material when\nstanding (in the absence of flow). Grain oscillations show a stick-slip\ncharacter only in the upper part of the silo.",
        "positive": "Microstructure and Soft Glassy Dynamics of Aqueous Laponite Dispersion: Synthetic hectorite clay Laponite RD/XLG is composed of disk-shaped\nnanoparticles that acquire dissimilar charges when suspended in an aqueous\nmedia. Owing to their property to spontaneously self-assemble, Laponite is used\nas a rheology modifier in a variety of commercial water-based products.\nParticularly, aqueous dispersion of Laponite undergoes liquid - to - solid\ntransition at about 1 volume % concentration. The evolution of the physical\nproperties as dispersion transforms to solid state is reminiscent of physical\naging in molecular as well as colloidal glasses. The corresponding soft glassy\ndynamics of an aqueous Laponite dispersion, including the rheological behavior,\nhas been extensively studied in the literature. In this feature article we take\nan overview of recent advances in understanding soft glassy dynamics and\nvarious efforts taken to understand the peculiar rheological behaviors.\nFurthermore, the continuously developing microstructure that is responsible for\neventual formation of soft solid state that supports its own weight against\ngravity has also been a topic of intense debate and discussion. Particularly\nextensive experimental and theoretical studies lead to two types of\nmicrostructures for this system: an attractive gel-like or repulsive glass\nlike. We carefully examine and critically analyze the literature and propose a\nstate diagram that suggests aqueous Laponite dispersion to be present in an\nattractive gel state."
    },
    {
        "anchor": "Crossover from Equilibration to Aging: (Non-equilibrium) Theory vs.\n  Simulations: Understanding glasses and the glass transition requires comprehending the\nnature of the crossover from the ergodic (or equilibrium) regime, in which the\nstationary properties of the system have no history dependence, to the\nmysterious glass transition region, where the measured properties are\nnon-stationary and depend on the protocol of preparation. In this work we use\nnon-equilibrium molecular dynamics simulations to test the main features of the\ncrossover predicted by the \\emph{molecular} version of the recently-developed\nmulticomponent non-equilibrium self-consistent generalized Langevin equation\n(NE-SCGLE) theory. According to this theory, the glass transition involves the\nabrupt passage from the ordinary pattern of full equilibration to the aging\nscenario characteristic of glass-forming liquids. The same theory explains that\nthis abrupt transition will always be observed as a blurred crossover by the\nunavoidable finiteness of the time window of any experimental observation. We\nfind that within their finite waiting-time window, the simulations confirm the\ngeneral trends predicted by the theory.",
        "positive": "Properties of hydrogen bonded network in ethanol-water liquid mixtures\n  as a function of temperature: diffraction experiments and computer\n  simulations: New X-ray and neutron diffraction experiments have been performed on\nethanol-water mixtures as a function of decreasing temperature, so that such\ndiffraction data are now available over the entire composition range. Extensive\nmolecular dynamics simulations show that the all-atom interatomic potentials\napplied are adequate for gaining insight of the hydrogen bonded network\nstructure, as well as of its changes on cooling. Various tools have been\nexploited for revealing details concerning hydrogen bonding, like determining\nH-bond acceptor and donor sites, calculating cluster size distributions and\ncluster topologies, as well as computing the Laplace spectra and fractal\ndimensions of the networks. It is found that 5-membered hydrogen bonded cycles\nare dominant up to an ethanol content of 70% at room temperature, above which\nconcentration ring structures nearly disappear. Percolation has been given\nspecial attention, so that it could be shown that at low temperature, close to\nthe freezing point even the mixture with 90% ethanol possesses a 3D percolating\nnetwork. Moreover, the water sub-network also percolates even at room\ntemperature, with a percolation transition occurring around 50% ethanol."
    },
    {
        "anchor": "Universality of the collapse transition of sticky polymers: The universality of the swelling of the radius of gyration of a homopolymer\nrelative to its value in the $\\theta$ state, independent of polymer-solvent\nchemistry, in the crossover regime between $\\theta$ and athermal solvent\nconditions, is well known. Here we study, by Brownian dynamics, a polymer model\nwhere a subset of monomers is labelled as \"stickers\". The mutual interaction of\nthe stickers is more attractive than those of the other (\"backbone\") monomers,\nand has the additional important characteristic of \"functionality\" $\\varphi$,\ni.e., the maximum number of stickers that can locally bind to a given sticker.\nA saturated bond formed in this manner remains bound until it breaks due to\nthermal fluctuations, a requirement which can be viewed as an additional\nBoolean degree of freedom that describes the bonding. This, in turn, makes the\nquestion of the order of the collapse transition a non-trivial one.\nNevertheless, for the parameters that we have studied (in particular,\n$\\varphi=1$), we find a standard second-order $\\theta$ collapse, using a\nrenormalised solvent quality parameter that takes into account the increased\naverage attraction due to the presence of stickers. We examine the swelling of\nthe radius of gyration of such a sticky polymer relative to its value in the\naltered $\\theta$ state, using a novel potential to model the various excluded\nvolume interactions that occur between the monomers on the chain. We find that\nthe swelling of such sticky polymers is identical to the universal swelling of\nhomopolymers in the thermal crossover regime. Additionally, for our model, the\nKuhn segment length under $\\theta$ conditions is found to be the same for\nchains with and without stickers.",
        "positive": "Phase separation dynamics in aqueous solutions of thermoresponsive\n  polymers: Phase transition kinetics of aqueous hydroxypropyl cellulose solution was\nstudied by using turbidimetric monitoring and mathematical modelling\ntechniques. Based on the nonlinear Cahn-Hilliard equation with a mobility\ndepending on the component concentration, the phase separation has been modeled\non a simple one-dimensional Flory lattice. For value set of the interfacial\nenergy parameter, data were obtained on the changing of the average values of\nthe cluster sizes, their mass and concentration. The simulation results allow\nus to distinguish three stages of the spinodal decomposition: early,\nintermediate and final. It was found that for the intermediate stage, the\nkinetics of the cluster mass growth is described by a dependence that is\ncharacteristic of the usual diffusion mass transfer; the change in the average\ncluster size can be represented by a scaling function with an exponent close to\n1/3, typical of the systems with a conserved scalar order parameter. It is\nshown that the concentration of clusters at the final stage is determined by\nthe temperature dependence of the interfacial energy."
    },
    {
        "anchor": "Repulsive torques alone trigger crystallization of constant speed active\n  particles: We investigate the possibility for self-propelled particles to crystallize\nwithout reducing their intrinsic speed. We illuminate how, in the absence of\nany force, the competition between self-propulsion and repulsive torques\ndetermine the macroscopic phases of constant-speed active particles. This\nminimal model expands upon existing approaches for an improved understanding of\ncrystallization of active matter.",
        "positive": "Reply to the Comments on \"Curvature capillary migration of microspheres\"\n  by P. Galatola and A. W\u007furger: We have studied microparticle migration on curved fluid interfaces in\nexperiment and derived an expression for the associated capillary energy $E$\nfor two cases, i.e., pinned contact lines and equilibrium contact lines, which\ndiffer from expressions derived by others in the literature. In this problem, a\nparticle of radius $a$ makes a disturbance in a large domain characterized by\nprincipal radii of curvature $R_1$ and $R_2$. Since $a$ is smaller than all\nassociated geometric and physico-chemical length scales, analysis calls for a\nsingular perturbation approach. We recapitulate these concepts, identify\nconceptual errors in the Comments about our work, and provide evidence from\nexperiment and simulation that supports our view."
    },
    {
        "anchor": "Towards understanding the geometry effects on fracture in thin elastic\n  shells: We examine how shell geometry affects fracture. As suggested by previous\nresults and our own phase-field simulations, shell shape dramatically affects\ncrack evolution and the effective toughness of the shell structure. To gain\ninsight and eventually develop new concepts for optimizing the design of thin\nshell structures, we derive the configurational force conjugate to crack\nextension for Koiter's linear thin shell theory. We identify the conservative\ncontribution to this force through an Eshelby tensor, as well as\nnon-conservative contributions arising from curvature.",
        "positive": "Energy Transfer within the Hydrogen Bonding Network of Water Following\n  Resonant Terahertz Excitation: Energy dissipation in water is very fast and more efficient than in many\nother liquids. This behavior is commonly attributed to the intermolecular\ninteractions associated with hydrogen bonding. Here, we investigate the dynamic\nenergy flow in the hydrogen-bond network of liquid water by a pump-probe\nexperiment. We resonantly excite intermolecular degrees of freedom with\nultrashort single-cycle terahertz pulses and monitor its Raman response. By\nusing ultrathin sample-cell windows, a background-free bipolar signal whose\ntail relaxes mono-exponentially is obtained. The relaxation is attributed to\nthe molecular translational motions, using complementary experiments,\nforce-field and ab initio molecular dynamics simulations. They reveal an\ninitial coupling of the terahertz electric field to the molecular rotational\ndegrees of freedom whose energy is rapidly transferred, within the excitation\npulse duration, to the restricted-translational motion of neighboring\nmolecules. This rapid energy transfer may be rationalized by the strong\nanharmonicity of the intermolecular interactions."
    },
    {
        "anchor": "Pushing the glass transition towards random close packing using\n  self-propelled hard spheres: Although the concept of random close packing with an almost universal packing\nfraction of ~ 0.64 for hard spheres was introduced more than half a century\nago, there are still ongoing debates. The main difficulty in searching the\ndensest packing is that states with packing fractions beyond the glass\ntransition at ~ 0.58 are inherently non-equilibrium systems, where the dynamics\nslows down with a structural relaxation time diverging with density; hence, the\nrandom close packing is inaccessible. Here we perform simulations of\nself-propelled hard spheres, and we find that with increasing activity the\nrelaxation dynamics can be sped up by orders of magnitude. The glass transition\nshifts to higher packing fractions upon increasing the activity, allowing the\nstudy of sphere packings with fluid-like dynamics at packing fractions close to\nrandom close packing. Our study opens new possibilities of investigating dense\npackings and the glass transition in systems of hard particles.",
        "positive": "Enhanced phase segregation induced by dipolar interactions in polymer\n  blends: We present a generalized theory for studying phase separation in blends of\npolymers containing dipoles on their backbone. The theory is used to construct\nco-existence curves and to study the effects of dipolar interactions on\ninterfacial tension for a planar interface between the coexisting phases. We\nshow that a mismatch in monomeric dipole moments, or equivalently a mismatch in\nthe dielectric constant of the pure components, leads to destabilization of the\nhomogeneous phase. Corrections to the Flory-Huggins phase diagram are predicted\nusing the theory. Furthermore, we show that the interfacial tension increases\nwith an increase in the mismatch of the dipole moments of the components.\nDensity profiles and interfacial tensions are constructed for diffuse and sharp\npolymer-polymer interfaces by extending the formalisms of Cahn-Hilliard and\nHelfand-Tagami-Sapse, respectively."
    },
    {
        "anchor": "Self-assembled guanine ribbons as wide-bandgap semiconductors: We present a first principle study about the stability and the electronic\nproperties of a new biomolecular solid-state material, obtained by the\nself-assembling of guanine (G) molecules. We consider hydrogen-bonded planar\nribbons in isolated and stacked configurations. These aggregates present\nelectronic properties similar to inorganic wide-bandgap semiconductors. The\nformation of Bloch-type orbitals is observed along the stacking direction,\nwhile it is negligible in the ribbon plane. Global band-like conduction may be\naffected by a dipole-field which spontaneously arises along the ribbon axis.\nOur results indicate that G-ribbon assemblies are promising materials for\nbiomolecular nanodevices, consistently with recent experimental results.",
        "positive": "Adhesion between a viscoelastic material and a solid surface: In this paper, we present a qualitative analysis of the dissipative processes\nduring the failure of the interface between a viscoelastic polymer and a solid\nsurface. We reassess the \"viscoelastic trumpet\" model [P.-G. de Gennes, C. R.\nAcad. Sci. Paris, 307, 1949 (1988)], and show that, for a crosslinked polymer,\nthe interface toughness G(V) starts from a relatively low value, G_0, due to\nlocal processes near the fracture tip, and rises up to a maximum of order $G_0\n(\\mu_{\\infty}/\\mu_0)$ (where $\\mu_0$ and $\\mu_{\\infty}$ stand for the elastic\nmodulus of the material, respectively at low and high strain frequencies). This\nenhancement of fracture energy is due to far-field viscous dissipation in the\nbulk material, and begins for peel-rates V much lower than previously thought.\nFor a polymer melt, the adhesion energy is predicted to scale as 1/V. In the\nsecond part of this paper, we compare some of our theoretical predictions with\nexperimental results about the viscoelastic adhesion between a\npolydimethylsiloxane polymer melt and a glass surface. In particular, the\nexpected dependence of the fracture energy versus separation rate is confirmed\nby the experimental data, and the observed changes in the concavity of the\ncrack profile are in good agreement with our simple model."
    },
    {
        "anchor": "Quantum vortices in systems obeying a generalized exclusion principle: The paper deals with a planar particle system obeying a generalized exclusion\nprinciple (EP) and governed, in the mean field approximation, by a nonlinear\nSchroedinger equation. We show that the EP involves a mathematically simple and\nphysically transparent mechanism, which allows the genesis of quantum vortices\nin the system. We obtain in a closed form the shape of the vortices and\ninvestigate its main physical properties.\n  PACS numbers: 03.65.-w, 03.65.Ge, 05.45.Yv",
        "positive": "A theory for the compression of two dimensional strongly aggregated\n  colloidal networks: The consolidation of suspended particulate matter under external forces such\nas pressure or gravity is of widespread interest. In this work, we derive a\nconstitutive relation to describe the deformation of a {\\it two-dimensional}\nstrongly aggregated colloidal system by incorporating the inter-particle\ncolloidal forces and contact dynamics. The theory accounts for the plastic\nevents that occur in the form of rolling/sliding during the deformation along\nwith elastic deformation. The theory predicts a yield stress that is a function\nof area fraction of the colloidal packing, the coordination number, the\ninter-particle potential, coefficient of friction and the normal and tangential\nstiffness coefficients. The predicted yield stress scales linearly with area\nfraction for low area fractions, and diverges at random close packing.\nIncreasing the normal stiffness coefficient or the friction coefficient\nincreases the yield stress. For stresses greater than the yield stress, both\nelastic and plastic deformations contribute to the overall stress."
    },
    {
        "anchor": "Hydrodynamic interaction of a self-propelling particle with a wall:\n  Comparison between an active Janus particle and a squirmer model: Using lattice Boltzmann simulations we study the hydrodynamics of an active\nspherical particle near a no-slip wall. We develop a computational model for an\nactive Janus particle, by considering different and independent mobilities on\nthe two hemispheres and compare the behaviour to a standard squirmer model.We\nshow that the topology of the far-field hydrodynamic nature of the active Janus\nparticle is similar to the standard squirmer model, but in the near-field the\nhydrodynamics differ. In order to study how the near-field effects affect the\ninteraction between the particle and a flat wall, we compare the behaviour of a\nJanus swimmer and a squirmer near a no-slip surface via extensive numerical\nsimulations. Our results show generally a good agreement between these two\nmodels, but they reveal some key differences especially with low magnitudes of\nthe squirming parameter $\\beta$. Notably the affinity of the particles to be\ntrapped at a surface is increased for the active Janus particles when compared\nto standard squirmers. Finally we find that when the particle is trapped on the\nsurface, the velocity parallel to the surface exceeds the bulk swimming speed\nand scales linearly with $|\\beta|$.",
        "positive": "Debye-H\u00fcckel Theory of Weakly Curved Macroions: Implementing Ion\n  Specificity through a Composite Coloumb-Yukawa Interaction Potential: The free energy of a weakly curved, isolated macroion embedded in a symmetric\n1:1 electrolyte solution is calculated on the basis of linear Debye-H\\\"uckel\ntheory, thereby accounting for non-electrostatic Yukawa pair interactions\nbetween the mobile ions and of the mobile ions with the macroion surface,\npresent in addition to the electrostatic Coulomb potential. The Yukawa\ninteractions between anion-anion, cation-cation, and anion-cation pairs are\nindependent from each other and serve as a model for solvent-mediated\nion-specific effects. We derive expressions for the free energy of a planar\nsurface, the spontaneous curvature, the bending stiffness, and the Gaussian\nmodulus. It is shown that a perturbation expansion, valid if the Yukawa\ninteractions make a small contribution to the overall free energy, yields\nsimple analytic results that exhibit good agreement with the general free\nenergy over the range of experimentally relevant interaction parameters."
    },
    {
        "anchor": "Highly strained mixtures of bidimensional soft and rigid grains: an\n  experimental approach from the local scale: Granular systems are not always homogeneous and can be composed of grains\nwith very different mechanical properties. To improve our understanding of the\nbehavior of real granular systems, in this experimental study, we compress 2D\nbidisperse systems made of both soft and rigid grains. By means of a recently\ndeveloped experimental set-up, \\md{from the measurement of the displacement\nfield we can} follow all the mechanical observables of this granular medium\nfrom the inside of each particle up-to-the whole system scale. We \\md{are able\nto} detect the jamming transition from these observables and study their\nevolution deep in the jammed state for packing fractions as high as $0.915$. We\nshow the uniqueness of the behavior of such a system, \\md{in which way} it is\nsimilar to purely soft or rigid systems and how it is different from them. This\nstudy constitutes the first step toward a better understanding of the\nmechanical behavior of granular materials that are polydisperse in terms of\ngrain rheology.",
        "positive": "Tuning gastropod locomotion: Modeling the influence of mucus rheology on\n  the cost of crawling: Common gastropods such as snails crawl on a solid substrate by propagating\nmuscular waves of shear stress on a viscoelastic mucus. Producing the mucus\naccounts for the largest component in the gastropod's energy budget, more than\ntwenty times the amount of mechanical work used in crawling. Using a simple\nmechanical model, we show that the shear-thinning properties of the mucus favor\na decrease in the amount of mucus necessary for crawling, thereby decreasing\nthe overall energetic cost of locomotion."
    },
    {
        "anchor": "Rayleigh waves and cyclotron surface modes of gyroscopic metamaterials: We investigate the elastic normal modes of two-dimensional media with broken\ntime-reversal and parity symmetries due to a Lorentz term. Our starting point\nis an elasticity theory that captures the low-energy physics of a diverse range\nof systems such as gyroscopic metamaterials, skyrmion lattices in thin-film\nchiral magnets and certain Wigner crystals. By focusing on a circular disk\ngeometry we analyze finite-size effects and study the low-frequency shape\noscillations of the disk. We demonstrate the emergence of the Rayleigh surface\nwaves from the bottom of the excitation spectrum and investigate how the\ncurvature of the disk-boundary modifies their propagation at long wavelengths.\nMoreover, we discover a near-cyclotron-frequency wave that is almost completely\nlocalized at the boundary of the disk, but is distinct from the Rayleigh wave.\nIt can be distinguished from the latter by a characteristic excitation pattern\nin a small region near the center of the disk.",
        "positive": "Microphase Separation in Random Multiblock Copolymers: Microphase separation in random multiblock copolymers is studied with\nmean-field theory assuming that long blocks of a copolymer are strongly\nsegregated, whereas short blocks are able to penetrate into \"alien\" domains and\nexchange between the domains and interfacial layer. A bidisperse copolymer with\nblocks of only two sizes (long and short) is considered as a model of\nmultiblock copolymers with high polydispersity in the block size. Short blocks\nof the copolymer play an important role in microphase separation. First, their\npenetration into the \"alien\" domains leads to the formation of joint long\nblocks in their own domains. Second, short blocks localized at the interface\nconsiderably change the interfacial tension. The possibility of penetration of\nshort blocks into the \"alien\" domains is controlled by the product chi*Nsh (chi\nis the Flory-Huggins interaction parameter, Nsh is the short block length). At\nnot very large chi*Nsh, the domain size is larger than that for a regular\ncopolymer consisting of the same long blocks as in the considered random\ncopolymer. At a fixed mean block size, the domain size grows with an increase\nin the block size dispersity, the rate of the growth being dependent of the\nmore detailed parameters of the block size distribution."
    },
    {
        "anchor": "Third-Order Gas-Liquid Phase Transition and the Nature of Andrews\n  Critical Point: The main objective of this article is to study the nature of the Andrews\ncritical point in the gas-liquid transition in a physical-vapor transport (PVT)\nsystem. A dynamical model, consistent with the van der Waals equation near the\nAndrews critical point, is derived. With this model, we deduce two physical\nparameters, which interact exactly at the Andrews critical point, and which\ndictate the dynamic transition behavior near the Andrews critical point. In\nparticular, it is shown that 1) the Andrews critical point is a switching point\nwhere the phase transition changes from the first order to the third order, 2)\nthe gas-liquid co-existence curve can be extended beyond the Andrews critical\npoint, and 3) the liquid-gas phase transition going beyond Andrews point is of\nthe third order. This clearly explains why it is hard to observe the gas-liquid\nphase transition beyond the Andrews critical point. Furthermore, the analysis\nleads naturally the introduction of a general asymmetry principle of\nfluctuations and the preferred transition mechanism for a thermodynamic system.",
        "positive": "The random walk of a low-Reynolds-number swimmer: Swimming at a micrometer scale demands particular strategies. Indeed when\ninertia is negligible as compared to viscous forces (i.e. Reynolds number $Re$\nis lower than unity), hydrodynamics equations are reversible in time. To\nachieve propulsion at low Reynolds number, swimmers must then deform in a way\nthat is not invariant under time reversal. Here, we investigate dispersal\nproperties of self propelled organisms by means of microscopy and cell\ntracking. Our system of interest is the micro-alga \\textit{Chlamydomonas\nReinhardtii}, a motile single celled green alga about 10 micrometers in\ndiameter that swims with to two front flagella. In the case of dilute\nsuspensions, we show that tracked trajectories are well modeled by a correlated\nrandom walk. This process is based on short time correlations in the direction\nof movement called persistence. At longer times, correlations are lost and a\nstandard random walk characterizes the trajectories. Moreover, high speed\nimaging enables us to show how the back-and-forth motion of flagella at very\nshort times affects the statistical description of the dynamics. Finally we\nshow how drag forces modify the characteristics of this particular random walk."
    },
    {
        "anchor": "Cellular solid behaviour of liquid crystal colloids. 1. Phase separation\n  and morphology: We study the phase ordering colloids suspended in a thermotropic nematic\nliquid crystal below the clearing point Tni and the resulting aggregated\nstructure. Small (150nm) PMMA particles are dispersed in a classical liquid\ncrystal matrix, 5CB or MBBA. With the help of confocal microscopy we show that\nsmall colloid particles densely aggregate on thin interfaces surrounding large\nvolumes of clean nematic liquid, thus forming an open cellular structure, with\nthe characteristic size of 10-100 micron inversely proportional to the colloid\nconcentration. A simple theoretical model, based on the Landau mean-field\ntreatment, is developed to describe the continuous phase separation and the\nmechanism of cellular structure formation.",
        "positive": "Viral self-assembly as a thermodynamic process: The protein shells, or capsids, of all sphere-like viruses adopt icosahedral\nsymmetry. In the present paper we propose a statistical thermodynamic model for\nviral self-assembly. We find that icosahedral symmetry is not expected for\nviral capsids constructed from structurally identical protein subunits and that\nthis symmetry requires (at least) two internal \"switching\" configurations of\nthe protein. Our results indicate that icosahedral symmetry is not a generic\nconsequence of free energy minimization but requires optimization of internal\nstructural parameters of the capsid proteins."
    },
    {
        "anchor": "Phase behavior in petroleum fluids (A Detailed Descriptive and\n  Illustrative Account): This chapter presents a descriptive and illustrative account of phase\nbehavior in the seven naturally occurring petroleum fluids and ties all the\nknown eleven phase-transition concepts in a unified narrative. The figures and\ntables contained in this report are designed so that they could effectively\nsupport the discussion about molecular make-up of petroleum fluids, P- and\nT-effects on phase behavior and phase transition points.\n  Seven naturally occurring hydrocarbon fluids are known as petroleum fluids.\nThey include, in the order of their fluidity, natural gas, gas-condensate\n(NGL), light crude, intermediate crude, heavy oil, tar sand and oil shale. In\nthis report we present a generalized description of the various phase\ntransitions, which may occur in petroleum fluids with emphasis on heavy\norganics deposition.\n  At first the nature of every petroleum fluid is presented. Their constituents\nincluding their socalled impurities are identified and categorized. Heavy\nfractions in petroleum fluids are discussed and their main families of\nconstituents are presented including petroleum wax, diamondoids, asphaltenes\nand petroleum resins. Then the generalized petroleum fluids phase behavior is\ndiscussed in light of the known theory of phase transitions. The effects of\nvariations of composition, temperature and pressure on the phase behavior of\npetroleum fluids are introduced. Finally eleven distinct phase-transition\npoints of petroleum fluids are presented and their relation with state\nvariables and constituents of petroleum fluids are identified. This report is\nto generalize and relate phase behaviors of all the seven naturally occurring\npetroleum fluids into a unified perspective. This work is the basis to develop\na comprehensive computational model for phase behavior prediction of all the\npetroleum fluids, which is of major interest in the petroleum industry.",
        "positive": "Turbulent-like fluctuations in quasistatic flow of granular media: We analyze particle velocity fluctuations in a simulated granular system\nsubjected to homogeneous quasistatic shearing. We show that these fluctuations\nshare the following scaling characteristics of fluid turbulence in spite of\ntheir different physical origins: 1) Scale-dependent probability distribution\nwith non-Guassian broadening at small time scales; 2) Power-law spectrum,\nreflecting long-range correlations and the self-affine nature of the\nfluctuations; 3) Superdiffusion with respect to the mean background flow."
    },
    {
        "anchor": "Multiscale Filler Structure in Simplified Industrial Nanocomposite\n  Silica/SBR Systems Studied by SAXS and TEM: Simplified silica (Zeosil 1165 MP) and SBR (140k carrying silanol end-groups)\nnanocomposites have been formulated by mixing of a reduced number of\ningredients with respect to industrial applications. The thermo-mechanical\nhistory of the samples during the mixing process was monitored and adjusted to\nidentical final temperatures. The filler structure on large scales up to\nmicrometers was studied by transmission electron microscopy (TEM) and very\nsmall-angle X-ray scattering (SAXS). A complete quantitative model extending\nfrom the primary silica nanoparticle (of radius \\approx 10 nm), to\nnanoparticles aggregates, up to micrometer-sized branches with typical lateral\ndimension of 150 nm is proposed. Image analysis of the TEM-pictures yields the\nfraction of zones of pure polymer, which extend between the branches of a\nlarge-scale filler network. This network is compatible with a fractal of\naverage dimension 2.4 as measured by scattering. On smaller length scales,\ninside the branches, small silica aggregates are present. Their average radius\nhas been deduced from a Kratky analysis, and it ranges between 35 and 40 nm for\nall silica fractions investigated here (\\phi_si = 8-21% vol.). A central piece\nof our analysis is the description of the interaggregate interaction by a\nsimulated structure factor for polydisperse spheres representing aggregates. A\npolydispersity of 30% in aggregate size is assumed, and interactions between\nthese aggregates are described with a hard core repulsive potential. The same\ndistribution in size is used to evaluate the polydisperse form factor.\nComparison with the experimental intensity leads to the determination of the\naverage aggregate compacity (assumed identical for all aggregates in the\ndistribution, between 31% and 38% depending on \\phi_si), and thus aggregation\nnumber (ca. 45, with a large spread). Because of the effect of aggregate\ncompacity and of pure polymer zones, the volume fraction of aggregates is\nhigher in the branches than \\phi_si. The repulsion between aggregates has a\nstrong effect on the apparent isothermal compressibility: it leads to a\ncharacteristic low-q depression, which cannot be interpreted as aggregate mass\ndecrease in our data. In addition, the reinforcement effect of these silica\nstructures in the SBR-matrix is characterized with oscillatory shear and\ndescribed with a model based on the same aggregate compacity. Finally, our\nresults show that it is possible to analyze the complex structure of\ninteracting aggregates in nanocomposites of industrial origin in a\nself-consistent and quantitative manner.",
        "positive": "Dynamics of growth and form in prebiotic vesicles: The growth, form, and division of prebiotic vesicles, membraneous bags of\nfluid of varying components and shapes is hypothesized to have served as the\nsubstrate for the origin of life. The dynamics of these out-of-equilibrium\nstructures is controlled by physicochemical processes that include the\nintercalation of amphiphiles into the membrane, fluid flow across the membrane,\nand elastic deformations of the membrane. To understand prebiotic vesicular\nforms and their dynamics, we construct a minimal model that couples membrane\ngrowth, deformation, and fluid permeation, ultimately couched in terms of two\ndimensionless parameters that characterize the relative rate of membrane growth\nand the membrane permeability. Numerical simulations show that our model\ncaptures the morphological diversity seen in extant precursor mimics of\ncellular life, and might provide simple guidelines for the synthesis of these\ncomplex shapes from simple ingredients."
    },
    {
        "anchor": "Dynamics of a linear magnetic \"microswimmer molecule\": In analogy to nanoscopic molecules that are composed of individual atoms, we\nconsider an active \"microswimmer molecule\". It is built up from three\nindividual magnetic colloidal microswimmers that are connected by harmonic\nsprings and hydrodynamically interact with each other. In the ground state,\nthey form a linear straight molecule. We analyze the relaxation dynamics for\nperturbations of this straight configuration. As a central result, with\nincreasing self-propulsion, we observe an oscillatory instability in accord\nwith a subcritical Hopf bifurcation scenario. It is accompanied by a\ncorkscrew-like swimming trajectory of increasing radius. Our results can be\ntested experimentally, using for instance magnetic self-propelled Janus\nparticles, supposably linked by DNA molecules.",
        "positive": "Fluctuating Filaments I: Statistical Mechanics of Helices: We examine the effects of thermal fluctuations on thin elastic filaments with\nnon-circular cross-section and arbitrary spontaneous curvature and torsion.\nAnalytical expressions for orientational correlation functions and for the\npersistence length of helices are derived, and it is found that this length\nvaries non-monotonically with the strength of thermal fluctuations. In the weak\nfluctuation regime, the local helical structure is preserved and the\nstatistical properties are dominated by long wavelength bending and torsion\nmodes. As the amplitude of fluctuations is increased, the helix ``melts'' and\nall memory of intrinsic helical structure is lost. Spontaneous twist of the\ncross--section leads to resonant dependence of the persistence length on the\ntwist rate."
    },
    {
        "anchor": "The double-faced electrostatic behavior of PNIPAm microgels: PNIPAm microgels synthesized via free radical polymerization (FRP) are often\nconsidered as neutral colloids in aqueous media, although it is well known,\nsince the pioneering work of Pelton and coworkers [Langmuir 1989, 5, 816-818],\nthat the vanishing electrophoretic mobility characterizing swollen microgels\nlargely increases above the lower critical solution temperature (LCST) of\nPNIPAm, at which microgels partially collapse. The presence of an electric\ncharge has been attributed to the ionic initiators that are employed when FRP\nis performed in water and that stay anchored to microgel particles. Combining\ndynamic light scattering (DLS), electrophoresis, transmission electron\nmicroscopy (TEM) and atomic force microscopy (AFM) experiments, we show that\ncollapsed ionic PNIPAm microgels undergo large mobility reversal and reentrant\ncondensation when they are co-suspended with oppositely charged\npolyelectrolytes (PE) or nanoparticles (NP), while their stability remains\nunaffected by PE or NP addition at lower temperatures, where microgels are\nswollen and their charge density is low. Our results highlight a somehow\ndouble-faced electrostatic behavior of PNIPAm microgels due to their tunable\ncharge density: they behave as quasi-neutral colloids at temperature below\nLCST, while they strongly interact with oppositely charged species when they\nare in their collapsed state. The very similar phenomenology encountered when\nmicrogels are surrounded by polylysine chains and silica nanoparticles points\nto the general character of this twofold behavior of PNIPAm-based colloids in\nwater.",
        "positive": "Influence of Creaming and Ripening on the Aggregation Rate of Non-Ionic\n  Dodecane-in-Water Nanoemulsions: The possible influence of creaming during the measurement of the aggregation\nrate of dodecane-in-water nanoemul- sions stabilized with Brij 30 is explored.\nFor this purpose additional emulsions made with a neutral-buoyancy oil (bro-\nmo-dodecane) and mixtures of dodecane and Br-dodecane with squalene were\nsynthesized. It is concluded that when the effect of ripening is suppressed,\nthe influence of buoyancy on the evaluation of the flocculation rate is\nnegligible. In the absence of squalene, ripening is present, and a sizeable\ndifference in the flocculation rate of dodecane and bro- mo-dodecane is\nobserved. However, this difference is not caused by the effect of gravity."
    },
    {
        "anchor": "Universal scattering behavior of co-assembled nanoparticle-polymer\n  clusters: Water-soluble clusters made from 7 nm inorganic nanoparticles have been\ninvestigated by small-angle neutron scattering. The internal structure factor\nof the clusters was derived and exhibited a universal behavior as evidenced by\na correlation hole at intermediate wave-vectors. Reverse Monte-Carlo\ncalculations were performed to adjust the data and provided an accurate\ndescription of the clusters in terms of interparticle distance and volume\nfraction. Additional parameters influencing the microstructure were also\ninvestigated, including the nature and thickness of the nanoparticle adlayer.",
        "positive": "Soft elastic surfaces as a platform for particle self-assembly: We perform numerical simulations to study self-assembly of nanoparticles\nmediated by an elastic planar surface. We show how the nontrivial elastic\nresponse to deformations of these surfaces leads to anisotropic interactions\nbetween the particles resulting in aggregates having different geometrical\nfeatures. The morphology of the patterns can be controlled by the mechanical\nproperties of the surface and the strength of the particle adhesion. We use\nsimple scaling arguments to understand the formation of the different\nstructures, and we show how the adhering particles can cause the underlying\nelastic substrate to wrinkle if two of its opposite edges are clamped. Finally,\nwe discuss the implications of our results and suggest how elastic surfaces\ncould be used in nanofabrication."
    },
    {
        "anchor": "Are large two-dimensional clusters of perimeter-minimizing bubbles of\n  equal-area hexagonal or circular?: A computer study of clusters of up to 200,000 equal-area bubbles shows for\nthe first time that rounding conjectured optimal hexagonal planar soap bubble\nclusters reduces perimeter.",
        "positive": "Soft Capacitors for Wave Energy Harvesting: Wave energy harvesting could be a substantial renewable energy source without\nimpact on the global climate and ecology, yet practical attempts have struggle\nd with problems of wear and catastrophic failure. An innovative technology for\nocean wave energy harvesting was recently proposed, based on the use of soft\ncapacitors. This study presents a realistic theoretical and numerical model for\nthe quantitative characterization of this harvesting method. Parameter regio ns\nwith optimal behavior are found, and novel material descriptors are determined\nwhich simplify analysis dramatically. The characteristics of currently ava\nilable material are evaluated, and found to merit a very conservative estimate\nof 10 years for raw material cost recovery."
    },
    {
        "anchor": "Computational Modeling of Electro-Elasto-Capillary Phenomena in\n  Dielectric Elastomers: We present a new finite deformation, dynamic finite element model that\nincorporates surface tension to capture elastocapillary effects on the\nelectromechanical deformation of dielectric elastomers. We demonstrate the\nsignificant effect that surface tension can have on the deformation of\ndielectric elastomers through three numerical examples: (1) surface tension\neffects on the deformation of single finite elements with homogeneous and\ninhomogeneous boundary conditions; (2) surface tension effects on instabilities\nin constrained dielectric elastomer films, and (3) surface tension effects on\nbursting drops in solid dielectrics. Generally, we find that surface tension\ncreates a barrier to instability nucleation. Specifically, we find in agreement\nwith recent experimental studies of constrained dielectric elastomer films a\ntransition in the surface instability mechanism depending on the\nelastocapillary length. The present results indicate that the proposed\nmethodology may be beneficial in studying the electromechanical deformation and\ninstabilities for dielectric elastomers in the presence of surface tension.",
        "positive": "The BCS-BEC Crossover in a Gas of Fermi Atoms with a Feshbach Resonance: We discuss the BCS-BEC crossover in a degenerate Fermi gas of two hyperfine\nstates interacting close to a Feshbach resonance. This system has\nquasi-molecular Bosons associated with a Feshbach resonance, and this kinds of\ncoupled Boson-Fermion model has been recently applied to Fermi atomic gases\nwithin a mean-field approximation. We show that by including fluctuation\ncontribution to the free energy similar to that condiered by Nozi'eres and\nSchmitt-Rink, the character of the superfluid phase transition continuously\nchanges from the BCS-type to the BEC-type, as the threshold of the\nquasi-molecular band is lowered. In the BEC regime, the quasi-molecules become\nstable long-lived composite Bosons, and an effective pairing interaction\nmediated by the molecules causes pre-formed Cooper-pairs to also be stable even\nabove the transition temperature Tc. The superfluid phase transition is shown\nto be usefully interpreted as the Bose condensation of these two kinds of\nBosons. The maximum Tc is given by (in terms of the Fermi temperature T_F)\nTc=0.218T_F (uniform gas) and Tc=0.518T_F (trapped gas in a harmonic\npotential)."
    },
    {
        "anchor": "To cross or not to cross: collective swimming of Escherichia coli under\n  two-dimensional confinement: Bacteria in bulk fluids swim collectively and display fascinating emergent\ndynamics. Although bacterial collective swimming in three-dimensional (3D)\ngeometries has been well studied, its counterpart in confined two-dimensional\n(2D) geometries relevant to natural habitats of bacteria is still poorly\nunderstood. Here, through carefully designed experiments on Escherichia coli in\nHele-Shaw chambers, we show that a small change in the degree of confinement\nleads to a drastic change in bacterial collective swimming. While long-range\nnematic order emerges for bacteria that can cross during encounters, a slight\ndecrease of the chamber height prevents the crossing, leading to the formation\nof bacterial clusters with short-range polar order. By tracking the swimming\nkinetics of individual bacteria, we reveal the microscopic origins of the two\ncollective phases. Our study provides important insights into bacterial\ncollective swimming under confinement and demonstrates a convenient way to\ncontrol the emergent symmetry of collective phases.",
        "positive": "Stretching of a Freely Jointed Chain in Two-Dimensions: Although the stretching of polymers and biomolecules is important in numerous\nsettings, their response when confined to two-dimensions is relatively\npoorly-studied. In this paper, we derive closed-form analytical expressions for\nthe two-dimensional force-extension response of a freely-jointed chain under\nforce control. Our principal results relate end-to-end distance to total force\nunder two modes of stretching: i) when force is applied only to the free of the\nchain, and ii) when the applied force is distributed uniformly throughout the\nchain. We have verified both analytical models by Brownian dynamics simulation\nof molecules adsorbed strongly to a substrate. The total force required is\nalways larger if distributed throughout the chain than when it is only applied\nto one end of the chain, and the nature of its divergence to infinity as\nextension approaches contour length is different."
    },
    {
        "anchor": "Unraveling hagfish slime: Hagfish slime is a unique predator defense material containing a network of\nlong fibrous threads each ~ 10 cm in length. Hagfish release the threads in a\ncondensed coiled state known as thread cells, or skeins (~ 100 microns), which\nmust unravel within a fraction of a second to thwart a predator attack. Here we\nconsider the hypothesis that viscous hydrodynamics can be responsible for this\nrapid unraveling, as opposed to chemical reaction kinetics alone. Our main\nconclusion is that, under reasonable physiological conditions, unraveling due\nto viscous drag can occur within a few hundred milliseconds, and is accelerated\nif the skein is pinned at a surface such as the mouth of a predator. We model a\nsingle thread cell unspooling as the fiber peels away due to viscous drag. We\ncapture essential features by considering one-dimensional scenarios where the\nfiber is aligned with streamlines in either uniform flow or uniaxial\nextensional flow. The peeling resistance is modeled with a power-law dependence\non peeling velocity. A dimensionless ratio of viscous drag to peeling\nresistance appears in the dynamical equations and determines the unraveling\ntimescale. Our modeling approach is general and can be refined with future\nexperimental measurements of peel strength for skein unraveling. It provides\nkey insights into the unraveling process, offers potential answers to lingering\nquestions about slime formation from threads and mucous vesicles, and will aid\nthe growing interest in engineering similar bioinspired material systems.",
        "positive": "Electrolyte solutions at curved electrodes. II. Microscopic approach: Density functional theory is used to describe electrolyte solutions in\ncontact with electrodes of planar or spherical shape. For the electrolyte\nsolutions we consider the so-called civilized model, in which all species\npresent are treated on equal footing. This allows us to discuss the features of\nthe electric double layer in terms of the differential capacitance. The model\nprovides insight into the microscopic structure of the electric double layer,\nwhich goes beyond the mesoscopic approach studied in the accompanying paper.\nThis enables us to judge the relevance of microscopic details, such as the\nradii of the particles forming the electrolyte solutions or the dipolar\ncharacter of the solvent particles, and to compare the predictions of various\nmodels. Similar to the preceding paper, a general behavior is observed for\nsmall radii of the electrode in that in this limit the results become\nindependent of the surface charge density and of the particle radii. However,\nfor large electrode radii non-trivial behaviors are observed. Especially the\nparticle radii and the surface charge density strongly influence the\ncapacitance. From the comparison with the Poisson-Boltzmann approach it becomes\napparent that the shape of the electrode determines whether the microscopic\ndetails of the full civilized model have to be taken into account or whether\nalready simpler models yield acceptable predictions."
    },
    {
        "anchor": "Dynamics of Sheared Ellipses and Circular Disks: Effects of Particle\n  Shape: Much recent effort has focused on glassy and jamming properties of spherical\nparticles. Very little is known about such phenomena for non-spherical\nparticles, and we take a first step by studying ellipses. We find important\ndifferences between the dynamical and structural properties of disks and\ntwo-dimensional ellipses subject to continuous Couette shear. In particular,\nellipses show slow dynamical evolution, without a counterpart in disks, in the\nmean velocity, local density, orientational order, and local stress. starting\nfrom an unjammed state, ellipses can first jam under shear, and then slowly\nunjam. The slow unjamming process is understood as a result of gradual changes\nin their orientations, leading to a denser packing. For disks, the rotation of\nparticles only contributes to relaxation of frictional forces, and hence, does\nnot significantly cause structural changes. For the shear-jammed states, the\nglobal building up and relaxation of stress, which occurs in the form of stress\navalanches, is qualitatively different for disks and ellipses, and is\nmanifested by different forms of rate-dependence for ellipses vs. disks. Unlike\nthe weak rate dependence typical for many granular systems, ellipses show\npower-law dependence on the shearing rate, {\\Omega}.",
        "positive": "Characterization of casein and Poly-L-arginine Multilayer Films: Thin films containing casein appear to be a promising material for coatings\nused in the medical area to promote biomineralization. alfa- and beta-casein\nand poly-L-arginine multilayer films were formed by the layer-by layer\ntechnique and their thickness and mass were analyzed by ellipsometry and quartz\ncrystal microbalance with dissipation monitoring (QCM-D). We investigated the\neffect of the type of casein used for the film formation and of the\npolyethyleneimine anchoring layer on the thickness and mass of adsorbed films.\nThe analysis of the mass of films during their post-treatment with the\nsolutions of various ionic strength and pH provided the information concerning\nfilms stability, while the XPS elemental analysis confirmed binding of calcium\nions by the casein embedded in the multilayers."
    },
    {
        "anchor": "Dependence of the viscosity on the chain end dynamics in polymer melts: We compare the Rubinstein-Duke model for reptation to a model where the\nboundary dynamics is modified by calculating the viscosity of polymer melts.\nThe question is investigated whether the viscosity is determined by details of\nthe dynamics of the polymer ends or by the stretching of the polymer. To this\nend the dependence of the viscosity on the particle density of the lattice gas\nmodels which can be identified by the stretching is determined. We show that\nthe influence of the stretching of the polymer on the absolute value of the\nviscosity in the scaling limit of of very long chains is much bigger than the\ninfluence of the boundary dynamics, whereas the corrections of the scaling of\nthe viscosity depends significantly on the details of the boundary dynamics.",
        "positive": "Identification of triangular-shaped defects often appeared in\n  hard-sphere crystals grown on a square pattern under gravity by Monte Carlo\n  simulations: In this paper, we have successfully identified the triangular-shaped defect\nstructures with stacking fault tetrahedra. These structure often appeared in\nhard-sphere (HS) crystals grown on a square pattern under gravity. We have, so\nfar, performed Monte Carlo simulations of the HS crystals under gravity. Single\nstacking faults as observed previously in the HS crystals grown on a flat wall\nwere not seen in the case of square template. Instead, defect structures with\ntriangular appearance in $xz$- and $yz$- projections were appreciable. We have\nidentified them by looking layer by layer. Those structures are surrounded by\nstacking faults along face-centered cubic (fcc) {111}. Also, we see isolated\nvacancies and vacancy-interstitial pairs, and we have found octahedral\nstructures surrounded by stacking faults along fcc {111}."
    },
    {
        "anchor": "Hydrodynamic Interactions Between Charged and Uncharged Brownian\n  Colloids at a Fluid-Fluid Interface: Hypothesis: The collective dynamics and self-assembly of colloids floating at\na fluid/fluid interface is a balance between deterministic lateral interaction\nforces, viscous resistance to colloid motion along the surface and thermal\n(Brownian) fluctuations. As the colloid size decreases, thermal forces become\nimportant and can affect the self assembly into ordered patterns and crystal\nstructures that are the starting point for various materials applications.\nNumerics: Langevin dynamic simulations involving two particles straddling a\nliquid/liquid interface with a high viscosity contrast are presented to\ndescribe the lateral interfacial assembly of particles in Brownian and\nnon-Brownian dominated regimes. These simulations incorporate capillary\nattraction, electrostatic repulsion, thermal fluctuations and HI between\nparticles (including the effect of the particle immersion depth). Simulation\nresults are presented for neutrally wetted particles which form a contact angle\nof 90 degrees at the interface. Findings: Clustering, fractal growth and\nparticle ordering are observed at critically large values of the Pe numbers,\nwhile smaller Pe numbers exhibit higher probabilities of yielding states in\nwhich particles remain uncorrelated in space and more widely separated.",
        "positive": "The crossover from single file to Fickian diffusion: The crossover from single-file diffusion, where the mean-square displacement\nscales as <x^2> ~t^(1/2), to normal Fickian diffusion, where <x^2>~t$, is\nstudied as a function of channel width for colloidal particles.\n  By comparing Brownian dynamics to a hybrid molecular dynamics and mesoscopic\nsimulation technique, we can study the effect of hydrodynamic interactions on\nthe single file mobility and on the crossover to Fickian diffusion for wider\nchannel widths. For disc-like particles with a steep interparticle repulsion,\nthe single file mobilities for different particle densities are well described\nby the exactly solvable hard-rod model. This holds both for simulations that\ninclude hydrodynamics, as well as for those that don't. When the single file\nconstraint is lifted, then for particles of diameter \\sigma and pipe of width\n$L$ such that (L- 2 \\sigma)/\\sigma = \\delta_c << 1 the particles can be\ndescribed as hopping past one-another in an average time t_{hop}. For shorter\ntimes t << t_{hop} the particles still exhibit sub-diffusive behaviour, but at\nlonger times t > t_{hop}, normal Fickian diffusion sets in with an effective\ndiffusion constant D_{hop} ~ t_{hop}^(1/2). For the Brownian particles, t_{hop}\n~ 1/\\delta_c^(2) when \\delta << 1, but when hydrodynamic interactions are\nincluded, we find a stronger dependence than \\delta_c^{-2}. We attribute this\ndifference to short-range lubrication forces that make it more difficult for\nparticles to hop past each other in very narrow channels."
    },
    {
        "anchor": "Motility fractionation of bacteria by centrifugation: Centrifugation is a widespread laboratory technique used to separate mixtures\ninto fractions characterized by a specific size, weight or density. We\ndemonstrate that centrifugation can be also used to separate swimming cells\nhaving different motility. To do this we study self-propelled bacteria under\nthe influence of an external centrifugal field. Using dynamic image correlation\nspectroscopy we measure the spatially resolved motility of bacteria after\ncentrifugation. A significant gradient in swimming-speeds is observed for\nincreasing centrifugal speeds. Our results can be reproduced by a model that\ntreats bacteria as \"hot\" colloidal particles having a diffusion coefficient\nthat depends on the swimming speed.",
        "positive": "Slow rheological mode in glycerol and glycerol-water mixtures: Glycerol-water mixtures were studied at molar concentrations ranging from\n$x_\\text{gly} = 1$ (pure glycerol) to $x_\\text{gly}=0.3$ using shear mechanical\nspectroscopy. We observed a low frequency mode in neat glycerol, similar to\nwhat is usually reported for monohydroxy alcohols. This mode has no dielectric\ncounterpart and disappears with increased water concentration. We propose that\nthe hydrogen-bonded network formed between glycerol molecules is responsible\nfor the observed slow mode and that water acts as a plasticizer for the overall\ndynamics and as a lubricant softening the hydrogen-bonding contribution to the\nmacroscopic viscosity of this binary system."
    },
    {
        "anchor": "Theoretical investigation of a polarizable colloid in the salt medium: In the present work, we have extended a weak coupling theory [A. Bakhshandeh,\nA. P. dos Santos and Y. Levin Phys. Rev. Lett 107, 107801 (2011)] for systems\nwith added 1:1 electrolyte. To study the accuracy of the developed theory, we\ncompare its numerical predictions with Monte Carlo simulation data and a recent\ntheory which accounts for the surface polarization. A very good agreement is\nfound for the case of monovalent electrolytes, up to very high salt\nconcentrations and different colloidal charges",
        "positive": "Colloid-polymer mixtures in random porous media: Finite size scaling and\n  connected versus disconnected susceptibilities: As a generic model for liquid-vapour type transitions in random porous media,\nthe Asakura-Oosawa model for colloid-polymer mixtures is studied in a matrix of\nquenched spheres using extensive Monte Carlo (MC) simulations. Since such\nsystems at criticality, as well as in the two-phase region, exhibit lack of\nself-averaging, the analysis of MC data via finite size scaling requires\nspecial care. After presenting the necessary theoretical background and the\nresulting subtleties of finite size scaling in random-field Ising-type systems,\nwe present data on the order parameter distribution (and its moments) as a\nfunction of colloid and polymer fugacities for a broad range of system sizes,\nand for many (thousands) realizations of the porous medium. Special attention\nis paid to the connected and disconnected susceptibilities, and their\nrespective critical behavior. We show that both susceptibilities diverge at the\ncritical point, and we demonstrate that this is compatible with the predicted\nscenario of random-field Ising universality."
    },
    {
        "anchor": "Design of Patchy Particles using Ternary Self-Assembled Monolayers: Recent simulations have studied the formation of patterns in a binary mixture\nof immiscible surfactants absorbed onto the surface of a spherical\nnanoparticle. The resulting patterns (Janus, spots and stripes) were in good\nagreement with experimental results. We perform dissipative particle dynamics\n(DPD) simulations to study the patterns obtained by adding a third surfactant\nto the monolayer as a guide towards increasing the richness and diversity of\npatchy particles synthesized this way. We predict a variety of new patterns\nthat can be produced through different combinations of simple design elements,\nlike nanocolloid size, degree of surfactant immiscibility, stoichiometry of the\nmonolayer, and length difference between surfactants. In all cases, free energy\nminimization through conformational entropy maximization determines equilibrium\npattern formation.",
        "positive": "Atomic motions in the $\u03b1\u03b2$-region of glass-forming polymers:\n  Molecular versus Mode Coupling Theory approach: We present fully atomistic Molecular Dynamics simulation results on a\nmain-chain polymer, 1,4-Polybutadiene, in the merging region of the $\\alpha$-\nand $beta$-relaxations. A real space analysis reveals the occurrence of\nlocalized motions (``$\\beta$-like'') in addition to the diffusive structural\nrelaxation. A molecular approach provides a direct connection between the local\nconformational changes reflected in the atomic motions and the secondary\nrelaxations in this polymer. Such local processes occur just in the time window\nwhere the $\\beta$-process of the Mode Coupling Theory is expected. We show that\nthe application of this theory is still possible, and yields an unusually large\nvalue of the exponent parameter. This result might originate from the\ncompetition between two mechanisms for dynamic arrest: intermolecular packing\nand intramolecular barriers for local conformational changes\n(``$\\beta$-like'')."
    },
    {
        "anchor": "Mechanical Response of a Small Swimmer Driven by Conformational\n  Transitions: A conformation space kinetic model is constructed to drive the deformation\ncycle of a three-sphere swimmer to achieve propulsion at low Reynolds number.\nWe analyze the effect of an external load on the performance of this kinetic\nswimmer, and show that it depends sensitively on where the force is exerted, so\nthat there is no general force--velocity relation. We discuss how the\nconformational cycle of such swimmers should be designed to increase their\nperformance in resisting forces applied at specific points.",
        "positive": "Using Mw dependence of surface dynamics of glassy polymers to probe the\n  length scale of free surface mobility: We describe a series of surface levelling experiments in glassy polystyrene\n(PS) of varying molecular weight. The evolution through a mobile surface layer\nis described by the glassy thin film equation that was introduced and used in a\nprevious work. Excellent agreement with the data is achieved, with surface\nmobility as the single free parameter. Different molecular-weight dependencies\nin mobility are then observed above and below the glass transition. The results\nare discussed in terms of surface-chain anchoring in the bulk matrix, and the\nlength scale for surface mobility."
    },
    {
        "anchor": "Critical adsorption of polyelectrolytes onto charged Janus nanospheres: Based on extensive Monte Carlo simulations and analytical considerations we\nstudy the electrostatically driven adsorption of flexible polyelectrolyte\nchains onto charged Janus nanospheres. These net-neutral colloids are composed\nof two equally but oppositely charged hemispheres. The critical binding\nconditions for polyelectrolyte chains are analysed as function of the radius of\nthe Janus particle and its surface charge density, as well as the salt\nconcentration in the ambient solution. Specifically for the adsorption of\nfinite-length polyelectrolyte chains onto Janus nanoparticles, we demonstrate\nthat the critical adsorption conditions drastically differ when the size of the\nJanus particle or the screening length of the electrolyte are varied. We\ncompare the scaling laws obtained for the adsorption-desorption threshold to\nthe known results for uniformly charged spherical particles, observing\nsignificant disparities. We also contrast the changes to the polyelectrolyte\nchain conformations and the binding energy distributions close to the\nadsorption-desorption transition for Janus nanoparticles to those for simple\nspherical particles. Finally, we discuss experimentally relevant\nphysico-chemical systems for which our simulations results may become\nimportant. In particular, we observe similar trends with polyelectrolyte\ncomplexation with oppositely but heterogeneously charged proteins.",
        "positive": "Structural relaxation in a system of dumbbell molecules: The interaction-site-density-fluctuation correlators, the dipole-relaxation\nfunctions, and the mean-squared displacements of a system of symmetric\ndumbbells of fused hard spheres are calculated for two representative\nelongations of the molecules within the mode-coupling theory for the evolution\nof glassy dynamics. For large elongations, universal relaxation laws for states\nnear the glass transition are valid for parameters and time intervals similar\nto the ones found for the hard-sphere system. Rotation-translation coupling\nleads to an enlarged crossover interval for the mean-squared displacement of\nthe constituent atoms between the end of the von Schweidler regime and the\nbeginning of the diffusion process. For small elongations, the superposition\nprinciple for the reorientational $\\alpha$-process is violated for parameters\nand time intervals of interest for data analysis, and there is a strong\nbreaking of the coupling of the $\\alpha$-relaxation scale for the diffusion\nprocess with that for representative density fluctuations and for dipole\nreorientations."
    },
    {
        "anchor": "Perturbation-induced granular fluidization as a model for remote\n  earthquake triggering: Studying the effect of mechanical perturbations on granular systems is\ncrucial for understanding soil stability, avalanches, and earthquakes. We\ninvestigate a granular system as a laboratory proxy for fault gouge. When\nsubjected to a slow shear, granular materials typically exhibit a stress\novershoot before reaching a steady state. We find that short seismic pulses can\nreset a granular system flowing in steady state so that the stress overshoot is\nregenerated. This new feature is shown to determine the stability of the\ngranular system under different applied stresses in the wake of a perturbation\npulse and the resulting dynamics when it fails. Using an analytical\naging-rejuvenation model for describing the overshoot response, we show that\nour laboratory-derived theoretical framework, can quantitatively explain data\nfrom two fault slip events triggered by seismic waves.",
        "positive": "Stringiness of Hyaluronic Acid Emulsions: In this work, we underline the importance of the molecular weight of\nhyaluronic acid on the elongational properties of concentrated emulsions. The\nfilament formation properties, e.g. the stringiness, of an emulsion is a key\ndeterminant of a product liking and repeat purchase. Here, we find that high\nmolecular weight hyaluronic acid and a high stretching speed are the control\nparameters affecting the filament formation of an emulsion."
    },
    {
        "anchor": "Flow of foam past an elliptical obstacle: To investigate the link between discrete, small-scale and continuous, large\nscale mechanical properties of a foam, we observe its two-dimensional flow in a\nchannel, around an elliptical obstacle. We measure the drag, lift and torque\nacting on the ellipse {\\it versus} the angle between its major axis and the\nflow direction. The drag increases with the spanwise dimension, in marked\ncontrast with a square obstacle. The lift passes through a smooth extremum at\nan angle close to, but smaller than 45$^\\circ$. The torque peaks at a\nsignificantly smaller angle, 26$^\\circ$. No existing model can reproduce the\nobserved viscous, elastic, plastic behavior. We propose a microscopic\nvisco-elasto-plastic model which agrees qualitatively with the data.",
        "positive": "Wide-gap Couette flows of dense emulsions: Local concentration\n  measurements, and comparison between macroscopic and local constitutive law\n  measurements through magnetic resonance imaging: Flows of dense emulsions show many complex features among which long range\nnonlocal effects pose a problem for macroscopic characterization. In order to\nget around this problem, we study the flows of several dense emulsions in a\nwide-gap Couette geometry. We couple macroscopic rheometric experiments and\nlocal velocity measurements through MRI techniques. As concentration\nheterogeneities can be expected, we designed a method to measure the local\ndroplet concentration in emulsions with a MRI device. In contrast to dense\nsuspensions of rigid particles where very fast migration occurs under shear, we\nshow that no migration takes place in dense emulsions even for strains as large\nas 100 000 in our systems. As a result of the absence of migration and of\nfinite size effect, we are able to determine very precisely the local\nrheological behavior of several dense emulsions. As the materials are\nhomogeneous, this behavior can also be inferred from purely macroscopic\nmeasurements. We thus suggest that properly analyzed purely macroscopic\nmeasurements in a wide-gap Couette geometry can be used as a tool to study the\nlocal constitutive laws of dense emulsions. All behaviors are basically\nconsistent with Herschel-Bulkley laws of index 0.5, but discrepancies exist at\nthe approach of the yield stress due to slow shear flows below the apparent\nyield stress in the case of a strongly adhesive emulsion. The existence of a\nconstitutive law accounting for all flows contrasts with previous results\nobtained within a microchannel by Goyon et al. (2008): the use of a wide-gap\nCouette geometry is likely to prevent here from nonlocal finite size effects;\nit also contrasts with the observations of B\\'ecu et al. (2006)."
    },
    {
        "anchor": "Impact of receptor-ligand distance on adhesion cluster stability: Cells in multicellular organisms adhere to the extracellular matrix through\ntwo-dimensional clusters spanning a size range from very few to thousands of\nadhesion bonds. For many common receptor-ligand systems, the ligands are\ntethered to a surface via polymeric spacers with finite binding range, thus\nadhesion cluster stability crucially depends on receptor-ligand distance. We\nintroduce a one-step master equation which incorporates the effect of\ncooperative binding through a finite number of polymeric ligand tethers. We\nalso derive Fokker-Planck and mean field equations as continuum limits of the\nmaster equation. Polymers are modeled either as harmonic springs or as\nworm-like chains. In both cases, we find bistability between bound and unbound\nstates for intermediate values of receptor-ligand distance and calculate the\ncorresponding switching times. For small cluster sizes, stochastic effects\ndestabilize the clusters at large separation, as shown by a detailed analysis\nof the stochastic potential resulting from the Fokker-Planck equation.",
        "positive": "Water evaporation from solute-containing aerosol droplets: effects of\n  internal concentration and diffusivity profiles and onset of crust formation: Saliva is primarily composed of water, but additionally includes a variety of\norganic and inorganic substances such as salt, proteins, peptides, mucins,\nvirions, etc. The presence of such solutes affects the evaporation time of\nrespiratory droplets that are sedimenting in air, and thereby the airborne\ntransmission of infections. From solutions of the coupled heat-conduction and\nwater-diffusion equations within the droplet and in the ambient vapor phase, we\nfind that the solute-induced water vapor-pressure reduction considerably slows\ndown the evaporation process and dominates the solute-concentration dependence\nof the droplet evaporation time. The evaporation-induced solute-concentration\ngradient near the droplet surface, which is accounted for using a two-stage\nevaporation model, is found to further intensify the slowing down of the drying\nprocess. On the other hand, the presence of solutes is found to reduce\nevaporation cooling of the droplet, which causes a slight decrease in the\nevaporation time. Overall, the first two effects are dominant, meaning that the\ndroplet evaporation time increases in the presence of solutes. The\nsolute-concentration dependence of the water diffusivity inside the droplet\ndoes not significantly change the evaporation time. Finally, crust formation on\nthe droplet surface is found to increase the final equilibrium size of the\ndroplet."
    },
    {
        "anchor": "Qualitative difference in rheology between fragile and network-forming\n  strong liquids: We elucidate a qualitative difference in rheology between fragile and\nnetwork-forming strong liquids. In a flow field, the structural configuration\nis distorted in accordance with the flow symmetry, whereas the form of the\ninteraction potential remains unchanged. The role of this mismatch in the\nrelaxation mechanism under the flow field is crucial for understanding the\nshear-thinning mechanism and differs between strong and fragile glass formers.\nIn fragile glass formers, shear thinning can be attributed to the shear-induced\nreduction of the {\\it effective density}. In contrast, in strong glass formers,\nthe shear-induced reduction of the {\\it effective activation energy} is a\npossible origin of a significant acceleration in relaxation. Our simple\npredictions of the crossover shear rate, $\\dot\\gamma_{\\rm c}$, from Newtonian\nto non-Newtonian behaviors can be expressed in terms of experimental\nobservables: in fragile liquids, $\\dot\\gamma_{\\rm c}=(\\rho \\partial\n\\tau_\\alpha/\\partial \\rho)^{-1}$, where $\\rho$ and $\\tau_\\alpha$ are the\ndensity and structural relaxation time, respectively, and in strong liquids,\n$\\dot\\gamma_{\\rm c}= (\\tau_\\alpha\\Delta E_0 /T)^{-1} $, where $T$ and $\\Delta\nE_0$ are the temperature and equilibrium activation energy, respectively. These\npredictions are consistent with the results of molecular dynamics simulations\nfor four different glass formers: two fragile and two strong ones. This\ndifferent route to the non-Newtonian flow response is related to differences in\nthe role of density in the relaxation dynamics.",
        "positive": "The rheology of hard sphere suspensions at arbitrary volume fractions:\n  An improved differential viscosity model: We propose a simple and general model accounting for the dependence of the\nviscosity of a hard sphere suspension at arbitrary volume fractions. The model\nconstitutes a continuum-medium description based on a recursive-differential\nmethod that assumes a hierarchy of relaxation times. Geometrical information of\nthe system is introduced through an effective volume fraction that approaches\nthe usual filling fraction at low concentrations and becomes one at maximum\npacking. The agreement of our expression for the viscosity with experiments at\nlow- and high-shear rates and in the high-frequency limit is remarkable for all\nvolume fractions."
    },
    {
        "anchor": "Jammed particulate systems are inherently nonharmonic: Jammed particulate systems, such as granular media, colloids, and foams,\ninteract via one-sided forces that are nonzero only when particles overlap. We\nfind that systems with one-sided repulsive interactions possess no linear\nresponse regime in the large system limit ($N\\rightarrow \\infty$) for all\npressures $p$ (or compressions $\\Delta \\phi$), and for all $N$ near jamming\nonset $p\\rightarrow 0$. We perform simulations on 2D frictionless bidisperse\nmechanically stable disk packings over a range of packing fractions $\\Delta\n\\phi = \\phi-\\phi_J$ above jamming onset $\\phi_J$. We apply perturbations with\namplitude $\\delta$ to the packings along each eigen-direction from the\ndynamical matrix and determine whether the response of the system evolving at\nconstant energy remains in the original eigenmode of the perturbation. For\n$\\delta > \\delta_c$, which we calculate analytically, a single contact breaks\nand fluctuations abruptly spread to all harmonic modes. As $\\delta$ increases\nfurther all discrete harmonic modes disappear into a continuous frequency band.\nWe find that $<\\delta_c >\\sim \\Delta \\phi/N^{\\lambda}$, where $1 > \\lambda >\n0.5$, and thus jammed particulate systems are inherently nonharmonic with no\nlinear vibrational response regime as $N\\rightarrow \\infty$ over the full range\nof $\\Delta \\phi$, and as $\\Delta \\phi \\rightarrow 0$ at any $N$.",
        "positive": "Identifying structural signature of dynamical heterogeneity via the\n  local softness parameter: In a recent study by some of us, we have proposed a new measure of the\nstructure of a liquid, the softness of the mean-field caging potential, and\nshown that it can describe the temperature dependence of the dynamics. In this\nwork, we put this parameter through a stringent test and study the causal\nrelationship between this softness parameter at the local level and the local\ndynamics. We first extend the earlier study to describe the local softness. We\nfind a distribution of the softness value where the distribution has reasonably\nstrong temperature dependence. This shows that the parameter can identify the\nlocal structural heterogeneity. We then study the lifetime of the softness\nparameter and show that its lifetime is connected to the well-known cage\nstructure in the supercooled liquids. Finally, our theory predicts that the\nlocal softness and the local dynamics is causal below the onset temperature\nwhere there is a decoupling between the short and long time dynamics, thus\nallowing a static description of the cage. We find that at lower temperatures,\nthe structural heterogeneity increases, and also, the structure becomes a\nbetter predictor of the dynamics, thus giving rise to dynamic heterogeneity. We\nalso find that the softness of a hard, immobile region evolves with time and\nbecomes soft and eventually mobile due to the rearrangements in the\nneighbourhood, confirming the well-known facilitation effect."
    },
    {
        "anchor": "Protein Enrichment by Flotation: Experiment and Modeling: Protein flotation is a process in which protein molecules are enriched by\nadsorption at rising bubbles. The bubbles then form a foam above the solution,\nwhere the liquid drains down and the dried foam, which is concentrated in\nprotein, is extracted. Here, the recovery rate and purity of the extract depend\non foam stability, surface coverage, bubble size, gas flow rate, etc. In this\nwork, we performed flotation experiments using bovine serum albumin (BSA). In\naddition, an unsteady state simulation of the protein flotation process was\ncarried out by numerically solving the liquid drainage equation in the foam.\nThereby, the extracted liquid volume and protein concentration at the outlet\nwere calculated with time. Required quantities such as foam stability,\ninterface coverage or bubble size distribution were measured in corresponding\nexperiments and were fed into the model. The experiments showed that the foam\ncoalescence accelerates the liquid drainage leading to dryer extract and higher\nprotein enrichment. The modeling also reproduced the liquid recovery and\nextract concentration of the flotation tests within a reasonable error range.\nThe modeling solely relies on experimental inputs and does not require any\ntuning parameters. It can be further used for optimization or up-scaling of\nprotein flotation.",
        "positive": "Differential dynamic microscopy for the characterization of polymer\n  systems: This review summarizes recent progress in investigating polymer systems by\nusing Differential dynamic microscopy (DDM), a rapidly emerging approach that\ntransforms a commercial microscope by combining real-space information with the\npowerful capabilities of conventional light scattering analysis. DDM analysis\nof a single microscope movie gives access to the sample dynamics in a wide\nrange of scattering wave-vectors, enabling contemporary polymer science\nexperiments that would be difficult or impossible with standard light\nscattering techniques. Examples of application include the characterization of\npolymer solutions and networks, of polymer based colloidal systems, of\nbiopolymers, and of cellular motility in polymeric fluids. Further applications\nof DDM to a variety of polymer systems are suggested to be just behind the\ncorner and it is thus likely that DDM will become a tool of choice of the\nmodern experimental polymer scientists."
    },
    {
        "anchor": "Network formation and gelation in Telechelic star polymers: We investigate the efficiency of gelation and network formation in telechelic\nstar polymer melt, where the tips of polymer arms are dipoles while rest of the\nmonomers are uncharged. Our work is motivated by the experimental observations\n[A.Kulkarni et.al, Macromolecules, {\\bf 48}, 6580 (2015)], in which rheological\nstudies of telechelic star polymers of poly-(L-actide), a bio-degradable\npolymer, showed a drastic increase in elastic properties (up to $2000$ times)\ncompared to corresponding star polymers without the telechelic arm ends. In\ncontrast to previous studies, we avoid using effective attractive Lennard Jones\npotentials or dipolar potentials to model telechelic interactions. Instead we\nuse explicit Coulomb positive and negative charges at the tip of polymer-arms\nof our bead-spring model of star polymers. By our simulations we show that the\ndipoles at the tip of star arms aggregate together to form clusters of dipoles.\nEach cluster has contribution from several stars, and in turn each star\ncontributes to several clusters. Thus the entire polymer melt forms a connected\nnetwork. Network forming tendencies decrease with decrease of the value of the\neffective charge constituting the dipole: this can be experimentally realized\nby choosing a different ionomer for the star tip. We systematically varied the\nvalue of dipole charges, the fraction of star-arms with dipoles at the tip and\nthe length of the arms. The choice of explicit charges in our calculations\nenables us to make better quantitative predictions about the onset of gelation,\nmoreover we get qualitatively distinct results about structural organization of\ndipoles within a dipole-cluster.",
        "positive": "Microgels and fractal structures at interfaces and surfaces: The behavior of microgels near surfaces and their adsorption is studied by\nsimple scaling theory. Two different types of microgels can be studied, i.e.,\nfractal type microgels and randomly crosslinked polymer chains. In the first\ncase the gel can be described mainly by introducing a spectral dimension. The\nsecond type requires more attention and uses the number of crosslinks as\nparameter. The main result is that soft gels with weakly coupled crosslinks and\na low number of crosslinks adsorb much better than hard gels, with many\ncrosslinks. Similar results for fractal gels and branched polymer are\npresented. Fractal gels with low connectivity adsorb easier than gels with a\nlarge connectivity dimension. We discuss also consequences on surface\nprotection by microgels."
    },
    {
        "anchor": "Equilibrium Onions?: We demonstrate the possibility of a stable equilibrium multi-lamellar\n(``onion'') phase in pure lamellar systems (no excess solvent) due to a\nsufficiently negative Gaussian curvature modulus. The onion phase is stabilized\nby non-linear elastic moduli coupled to a polydisperse size distribution\n(Apollonian packing) to allow space-filling without appreciable elastic\ndistortion. This model is compared to experiments on copolymer-decorated\nlamellar surfactant systems, with reasonable qualitative agreement.",
        "positive": "Multiple passages of light through an absorption inhomogeneity in\n  optical imaging of turbid media: The multiple passages of light through an absorption inhomogeneity of finite\nsize deep within a turbid medium is analyzed for optical imaging using the\n``self-energy'' diagram. The nonlinear correction becomes more important for an\ninhomogeneity of a larger size and with greater contrast in absorption with\nrespect to the host background. The nonlinear correction factor agrees well\nwith that from Monte Carlo simulations for CW light. The correction is about\n$50%-75%$ in near infrared for an absorption inhomogeneity with the typical\noptical properties found in tissues and of size of five times the transport\nmean free path."
    },
    {
        "anchor": "The thermal jamming transition of soft harmonic disks in two dimensions: By exploring the properties of the energy landscape of a bidisperse system of\nsoft harmonic disks in two dimensions we determine the thermal jamming\ntransition. To be specific, we study whether the ground state of the system\nwhere the particle do not overlap can be reached within a reasonable time.\nStarting with random initial configurations, the energy landscape is probed by\nenergy minimization steps as in case of athermal jamming and in addition steps\nwhere an energy barrier can be crossed with a small but non-zero probability.\nFor random initial conditions we find that as a function of packing fraction\nthe thermal jamming transition, i.e. the transition from a state where all\noverlaps can be removed to an effectively non-ergodic state where one cannot\nget rid of the overlaps, occurs at a packing fraction of $\\phi_G=0.74$, which\nis smaller than the transition packing fraction of athermal jamming at\n$\\phi_J=0.842$. Furthermore, we show that the thermal jamming transition is in\nthe universality class of directed percolation and therefore is fundamentally\ndifferent from the athermal jamming transition.",
        "positive": "Making a splash with water repellency: A 'splash' is usually heard when a solid body enters water at large velocity.\nThis phenomena originates from the formation of an air cavity resulting from\nthe complex transient dynamics of the free interface during the impact. The\nclassical picture of impacts on free surfaces relies solely on fluid inertia,\narguing that surface properties and viscous effects are negligible at\nsufficiently large velocities. In strong contrast to this large-scale\nhydrodynamic viewpoint, we demonstrate in this study that the wettability of\nthe impacting body is a key factor in determining the degree of splashing. This\nunexpected result is illustrated in Fig.1: a large cavity is evident for an\nimpacting hydrophobic sphere (1.b), contrasting with the hydrophilic sphere's\nimpact under the very same conditions (1.a). This unforeseen fact is\nfurthermore embodied in the dependence of the threshold velocity for air\nentrainment on the contact angle of the impacting body, as well as on the ratio\nbetween the surface tension and fluid viscosity, thereby defining a critical\ncapillary velocity. As a paradigm, we show that superhydrophobic impacters make\na big 'splash' for any impact velocity. This novel understanding provides a new\nperspective for impacts on free surfaces, and reveals that modifications of the\ndetailed nature of the surface -- involving physico-chemical aspects at the\nnanometric scales -- provide an efficient and versatile strategy for\ncontrolling the water entry of solid bodies at high velocity."
    },
    {
        "anchor": "An in-vivo study of electrical charge distribution on the bacterial cell\n  wall by Atomic Force Microscopy in vibrating force mode: We report an in-vivo electromechanical Atomic Force Microscopy (AFM) study of\ncharge distribution on the cell wall of Gram plus Rhodococcus wratislaviensis\nbacteria, naturally adherent to a glass substrate, in physiological conditions.\nThe method presented in this paper relies on a detailed study of AFM\napproach-retract curves giving the variation of the interaction force versus\ndistance between tip and sample. In addition to classical height and mechanical\n(as stiffness) data, mapping of local electrical properties, as bacterial\nsurface charge, was proved to be feasible at a spatial resolution better than\nfew tens of nanometers. This innovative method relies on the measurement of the\ncantilever's surface stress through its deflection far from (higher than 10nm)\nthe repulsive contact zone. The variations of surface stress come from\nmodification of electrical surface charge of the cantilever (as in classical\nelectrocapillary measurements) likely stemming from its charging during contact\nof both tip and sample electrical double layers. This method offers an\nimportant improvement in local electrical and electrochemical measurements at\nthe solid-liquid interface particularly in high-molarity electrolytes when\ncompared to technics focused on the direct use of electrostatic force. It thus\nopens a new way to directly investigate in-situ biological electrical surface\nprocesses involved in numerous practical and fundamental problems as bacterial\nadhesion, biofilm formation, microbial fuel cell, etc.",
        "positive": "Secondary relaxation in the terahertz range in 2-adamantanone from\n  theory and experiments: We applied the recently developed Generalized Langevin Equation (GLE)\napproach for dielectric response of liquids and glasses to link the vibrational\ndensity of states (VDOS) to the dielectric response of a model orientational\nglass (OG). The dielectric functions calculated based on the GLE, with VDOS\nobtained in experiments and simulations as inputs, are compared with\nexperimental data for the paradigmatic case of 2-adamantanone at various\ntemperatures. The memory function is related to the integral of the VDOS times\na spectral coupling function $\\gamma(\\omega_p)$, which tells the degree of\ndynamical coupling between molecular degrees of freedom at different\neigenfrequencies. With respect to previous empirical fittings, the GLE-based\nfitting reveals a broader temperature range over which the secondary relaxation\nis active. Furthermore, the theoretical analysis provides a clear evidence of\nsecondary relaxation being localized within the THz ($0.5-1$ THz) range of\neigenfrequencies, and thus not too far from the low-energy modes involved in\n$\\alpha$-relaxation. In the same THz region, the same material displays a\ncrowding of low-energy optical modes that may be related to the secondary\nrelaxation."
    },
    {
        "anchor": "Effect of speed fluctuations on the collective dynamics of active disks: Numerical simulations are performed on the collective dynamics of active\ndisks, whose self-propulsion speed ($U$) varies in time, and whose orientation\nevolves according to rotational Brownian motion. Two protocols for the\nevolution of speed are considered: (i) a deterministic one involving a periodic\nchange in $U$ at a frequency $\\omega$; and (ii) a stochastic one in which the\nspeeds are drawn from a power-law distribution at time-intervals governed by a\nPoissonian process of rate $\\beta$. In the first case, an increase in $\\omega$\ncauses the disks to go from a clustered state to a homogeneous one through an\napparent phase-transition, provided that the direction of self-propulsion is\nallowed to reverse. Similarly, in the second case, for a fixed value of\n$\\beta$, the extent of cluster-breakup is larger when reversals in the\nself-propulsion direction are permitted. Motility-induced phase separation of\nthe disks may therefore be avoided in active matter suspensions in which the\nconstituents are allowed to reverse their self-propulsion direction, immaterial\nof the precise temporal nature of the reversal (deterministic or stochastic).\nEqually, our results demonstrate that phase separation could occur even in the\nabsence of a time-averaged motility of an individual active agent, provided\nthat the rate of direction reversals is smaller than the orientational\ndiffusion rate.",
        "positive": "Directed transport of active particles over asymmetric energy barriers: We theoretically and numerically investigate the transport of active colloids\nto target regions, delimited by asymmetric energy barriers. We show that it is\npossible to introduce a generalized effective temperature that is related to\nthe local variance of particle velocities. The stationary probability\ndistributions can be derived from a simple diffusion equation in the presence\nof an inhomogeneous effective temperature resulting from the action of external\nforce fields. In particular, transitions rates over asymmetric energy barriers\ncan be unbalanced by having different effective temperatures over the two\nslopes of the barrier. By varying the type of active noise, we find that equal\nvalues of diffusivity and persistence time may produce strongly varied\neffective temperatures and thus stationary distributions."
    },
    {
        "anchor": "Evaluating linear response in active systems with no perturbing field: We present a method for the evaluation of time-dependent linear response\nfunctions for systems of active Ornstein-Uhlenbeck particles from unperturbed\nsimulations. The method is inspired by the Malliavin weights sampling method\nproposed by Warren and Allen [Phys. Rev. Lett. 109, 250601 (2012)] for systems\nof Brownian particles. We illustrate our method by evaluating a linear response\nfunction for a single active particle in an external harmonic potential. As an\napplication, we calculate the time-dependent mobility function and an effective\ntemperature, defined through the Einstein relation between the self-diffusion\nand mobility coefficients, for a system of active particles interacting via a\nscreened-Coulomb potential. We find that this effective temperature decreases\nwith increasing persistence time of the self-propulsion. Initially, for not too\nlarge persistence times, it changes rather slowly, but then it decreases\nmarkedly when the persistence length of the self-propelled motion becomes\ncomparable with the particle size.",
        "positive": "Effects of local incompressibility on the rheology of composite\n  biopolymer networks: Fibrous networks such as collagen are common in biological systems. Recent\ntheoretical and experimental efforts have shed light on the mechanics of single\ncomponent networks. Most real biopolymer networks, however, are composites made\nof elements with different rigidity. For instance, the extracellular matrix in\nmammalian tissues consists of stiff collagen fibers in a background matrix of\nflexible polymers such as hyaluronic acid (HA). The interplay between different\nbiopolymer components in such composite networks remains unclear. In this work,\nwe use 2D coarse-grained models to study the nonlinear strain-stiffening\nbehavior of composites. We introduce a local volume constraint to model the\nincompressibility of HA. We also perform rheology experiments on composites of\ncollagen with HA. We demonstrate both theoretically and experimentally that the\nlinear shear modulus of composite networks can be increased by approximately an\norder of magnitude above the corresponding moduli of the pure components. Our\nmodel shows that this synergistic effect can be understood in terms of the\nlocal incompressibility of HA, which acts to suppress density fluctuations of\nthe collagen matrix with which it is entangled."
    },
    {
        "anchor": "Imbibition through an array of triangular posts: We present and interpret simulation results showing how a fluid moves on a\nhydrophilic substrate patterned by a square array of triangular posts. We\ndemonstrate that the shape of the posts leads to anisotropic spreading, and\ndiscuss how this is influenced by the different ways in which the posts can pin\nthe advancing front.",
        "positive": "Ultracold atom-molecule mixture gases in a harmonic trap: This paper has been withdrawn."
    },
    {
        "anchor": "Diverging time scale in the dimensional crossover for liquids in strong\n  confinement: We study a strongly interacting dense hard-sphere system confined between two\nparallel plates by event-driven molecular dynamics simulations to address the\nfundamental question of the nature of the 3D to 2D crossover. As the fluid\nbecomes more and more confined the dynamics of the transverse and lateral\ndegrees of freedom decouple, which is accompanied by a diverging time scale\nseparating 2D from 3D behavior. Relying on the time-correlation function of the\ntransversal kinetic energy the scaling behavior and its density-dependence is\nexplored. Surprisingly, our simulations reveal that its time-dependence becomes\npurely exponential such that memory effects can be ignored. We rationalize our\nfindings quantitatively in terms of an analytic theory which becomes exact in\nthe limit of strong confinement.",
        "positive": "Electronic properties of DNA: structural and chemical influence on the\n  quest for high conductance and charge transfer: Motivated by the wide ranging experimental results on the conductivity of\nDNA, we have investigated extraordinary configurations and chemical\nenvironments in which DNA might become a true molecular wire, perticularly from\nenhanced electronic overlaps or from small activation energies. In particular,\nwe examine A- vs B-DNA, the ribbon-like structures proposed to arise from\nmolecular stretching, the potential role of counterions in hole doping the DNA\norbitals, the possibility of backbone conduction, and the effects of water. We\nfind that small activation gaps observed in conductivity experiments may arise\nin the presence of water and counter ions. We further discuss the role of\nharmonic vibration and twisting motion on electron tight binding matrix\nelements using ab initio density functional theory and model Koster-Slater\ntheory calculations. We find that partial cancellation between pp-sigma and\npp-pi interaction of Pz orbitals on adjacent base pairs, along with destructive\ninterference of phase factors are needed to explain the weak conductance of\nA-DNA. Our results lead also to a physical interpretation of the angular\ndependence of inter-base pair tight binding matrix elements. Furthermore, we\nestimate Franck-Condon factors, reorganization energies and nuclear frequencies\nessential for charge transfer rates, and find our estimated hole transfer rates\nbetween base pairs to be in excellent agreement with recent picosecond dynamics\ndata."
    },
    {
        "anchor": "Phase behaviour of a simple model of globular proteins: A simple model of globular proteins which incorporates anisotropic\nattractions is proposed. It is closely related to models used to model simple\nhydrogen-bonding molecules such as water. Theories for both the fluid and solid\nphases are presented, and phase diagrams calculated. The model protein exhibits\na fluid-fluid transition which is metastable with respect to the fluid-solid\ntransition for most values of the model parameters. This is behaviour often\nobserved for globular proteins. The model offers an explanation of the\ndifficulty observed in crystallising some globular proteins and suggests that\nsome proteins may not have a solid phase at all under all but extreme\nconditions.",
        "positive": "Synchronous phase clustering in a network of neurons with spatially\n  decaying excitatory coupling: Synchronization is studied in a spatially-distributed network of\nweekly-coupled, excitatory neurons of Hodgkin-Huxley type. All neurons are\ncoupled to each other synaptically with a fixed time delay and a coupling\nstrength inversely proportional to the distance between two neurons. We found\nthat a robust, noise-resistant phase clustering state occurred regardless of\nthe initial phase distribution. This has not been shown in previous studies\nwhere similar clustering states were found only when the coupling was\ninhibitory. The spatial distribution of neurons in each synchronous cluster is\ndetermined by the spatial distribution of the coupling strength.\nPhase-interaction properties of the model neurons in the network are used to\nexplain why can such a clustering state be robust."
    },
    {
        "anchor": "Competing ferromagnetic and nematic alignment in self-propelled polar\n  particles: We study a Vicsek-style model of self-propelled particles where ferromagnetic\nand nematic alignment compete in both the usual \"metric\" version and in the\n\"metric-free\" case where a particle interacts with its Voronoi neighbors. We\nshow that the phase diagram of this out-of-equilibrium XY model is similar to\nthat of its equilibrium counterpart: the properties of the fully-nematic model,\nstudied before in [F. Ginelli, F. Peruani, M. Baer, and H. Chat\\'e, Phys. Rev.\nLett. 104, 184502 (2010)], are thus robust to the introduction of a modest bias\nof interactions towards ferromagnetic alignment. The direct transitions between\npolar and nematic ordered phases are shown to be discontinuous in the metric\ncase, and continuous, belonging to the Ising universality class, in the\nmetric-free version.",
        "positive": "Navier--Stokes transport coefficients for a model of a confined\n  quasi-two-dimensional granular binary mixture: The Navier--Stokes transport coefficients for a model of a confined\nquasi-two-dimensional granular binary mixture of inelastic hard spheres are\ndetermined from the Boltzmann kinetic equation. A normal or hydrodynamic\nsolution to the Boltzmann equation is obtained via the Chapman--Enskog method\nfor states near the local version of the homogeneous time-dependent state. The\nmass, momentum, and heat fluxes are determined to first order in the spatial\ngradients of the hydrodynamic fields, and the associated transport coefficients\nare identified. As expected, they are given in terms of the solutions of a set\nof coupled linear integral equations. In addition, in contrast to previous\nresults obtained for low-density granular mixtures, there are also nonzero\ncontributions to the first-order approximations to the partial temperatures\n$T_i^{(1)}$ and the cooling rate $\\zeta^{(1)}$. Explicit forms for the\ndiffusion transport coefficients, the shear viscosity coefficient, and the\nquantities $T_i^{(1)}$ and $\\zeta^{(1)}$ are obtained by assuming the\nsteady-state conditions and by considering the leading terms in a Sonine\npolynomial expansion. The above transport coefficients are given in terms of\nthe coefficients of restitution, concentration, and the masses and diameters of\nthe components of the mixture. The results apply in principle for arbitrary\ndegree of inelasticity and are not limited to specific values of concentration,\nmass and/or size ratios. As a simple application of these results, the\nviolation of the Onsager reciprocal relations for a confined granular mixture\nis quantified in terms of the parameter space of the problem."
    },
    {
        "anchor": "Self-organized vortex phases and hydrodynamic interactions in Bos taurus\n  sperm cells: Flocking behavior is observed in biological systems from the cellular to\nsuper-organismal length scales, and the mechanisms and purposes of this\nbehavior are objects of intense interest. In this paper, we study the\ncollective dynamics of bovine sperm cells in a viscoelastic fluid. Remarkably,\nthese cells appear not to spontaneously flock, but transition into a long-lived\nflocking phase after being exposed to a transient ordering pulse of fluid flow.\nSurprisingly, this induced flocking phase exhibits anisotropic giant number\nfluctuations and possesses transverse density fluctuation correlations\nconsistent with the Toner-Tu theory of the polar fluid phase, despite the\nclearly important role of momentum conservation between the swimmers and the\nsurrounding fluid in these experiments. In addition to these flow-induced\nflocking states, we also find a self-organized global vortex state of the sperm\ncells. We simulate this system, modeling the sperm as persistently turning\nactive particles. Although the model does not reproduce the vortex state, it\nexhibits a polar-disorder phase boundary as a function of cell density and\npersistence time that is predictive of the experimental phase boundary. Our\nresults may have implications for the evaluation of sample fertility by\nstudying the collective phase behavior of dense groups of swimming sperm.",
        "positive": "Micro-Bullet Assembly: Interactions of Oriented Dipoles in Confined\n  Nematic Liquid Crystal: Microbullet particles, cylinders with one blunt and one spherical end, offer\na novel platform to study the effects of anisotropy and curvature on colloidal\nassembly in complex fluids. Here, we disperse microbullets in\n4-cyano-4'-pentylbiphenyl (5CB) nematic liquid crystal (NLC) cells and form\noriented elastic dipoles with a nematic point defect located near the curved\nend. This feature allows us to study particle interactions as a function of\ndipole alignment. By careful control of the surface anchoring at the particle\nsurface and the confining boundaries, we study the interactions and assembly of\nmicrobullets under various conditions. When microbullets with homeotropic\nsurface anchoring are dispersed in a planar cell, parallel dipoles form linear\nchains parallel to the director, similar to the observations of spherical\nparticles in a planar cell, while antiparallel dipoles orient side-to-side. In\na homeotropic cell, however, particles rotate to orient their long axis\nparallel to the director. When so aligned, parallel dipoles repel and form 2D\nordered assemblies with hexagonal symmetry that ripen over time owing to\nattraction between antiparallel neighbors. Further, we show that the anchoring\nconditions inside the cell can be altered by application of an electrical\nfield, allowing us to flip microbullets to orient parallel to the director, an\neffect driven by an elastic torque. Finally, we detail the mechanisms that\ncontrol the formation of 1D chains and hexagonal lattices with respect to the\nelasticity of the NLC."
    },
    {
        "anchor": "Elasticity and Plasticity in Stiff and Flexible Oligomeric Glasses: In this paper we focus on the mechanical properties of oligomeric glasses\n(waxes), employing a microscopic model that provides, via numerical\nsimulations, information about the shear modulus of such materials, the failure\nmechanism via plastic instabilities and about the geometric responses of the\noligomers themselves to a mechanical load. We present a microscopic theory that\nexplains the numerically observed phenomena, including an exact theory of the\nshear modulus and of the plastic instabilities, both local and system spanning.\nIn addition we present a model to explain the geometric changes in the\noligomeric chains under increasing strains.",
        "positive": "Continuum theories of structured dielectrics: Aequous dielectrics are ubiquitous in soft- and bio-nano matter systems. The\ntheoretical description of such systems in terms of continuum (`macroscopic')\ntheory remains a serious challenge. In this perspective we first review the\nexisting continuum phenomenological approaches that have been developed in the\npast decades. In order to describe a path to advance continuum theory beyond\nthese approaches we then take recourse to the Onsager-Dupuis theory of the\ndielectric behaviour of ice, which, for the case of a solid dielectric,\nexemplified important conceptual issues we deem relevant for the development of\na more fundamental continuum theory of liquid dielectrics. Subsequently, we\ndiscuss our recently proposed continuum field theory of structured dielectrics,\nwhich provides a generalized approach to the dielectric behavior of such\nsystems."
    },
    {
        "anchor": "Dynamics and instantaneous normal modes in a liquid with density\n  anomalies: We investigate the relation between the dynamical features of a supercooled\nliquid and those of its potential energy landscape, focusing on a model liquid\nwith density anomalies. We consider, at fixed temperature, pairs of state\npoints with different density but the same diffusion constant, and find that\nsurprisingly they have identical dynamical features at all length and time\nscales. This is shown by the collapse of their mean square displacements and of\ntheir self--intermediate scattering functions at different wavevectors. We then\ninvestigate how the features of the energy landscape change with density, and\nestablish that state points with equal diffusion constant have different\nlandscapes. In particular, we find a correlation between the fraction of\ninstantaneous normal modes connecting different energy minima and the diffusion\nconstant, but unlike in other systems these two quantities are not in\none--to--one correspondence with each other, showing that additional landscape\nfeatures must be relevant in determining the diffusion constant.",
        "positive": "Anomalous elasticity of nematic elastomers: We study the anomalous elasticity of nematic elastomers by employing the\npowers of renormalized field theory. Using general arguments of symmetry and\nrelevance, we introduce a minimal Landau-Ginzburg-Wilson elastic energy for\nnematic elastomers. Performing a diagrammatic low temperature expansion, we\nanalyze the fluctuations of the displacement fields at and below the upper\ncritical dimension 3. Our analysis reveals an anomaly of certain elastic moduli\nin the sense that they depend on the length scale. In $d = 3$ this dependence\nis logarithmic and below $d=3$ it is of power law type with anomalous scaling\nexponents. One of the 4 relevant shear moduli vanishes at long length scales\nwhereas the only relevant bending modulus diverges."
    },
    {
        "anchor": "Grand canonical simulation of phase behaviour in highly\n  size-asymmetrical binary fluids: We describe a Monte Carlo scheme for the grand canonical simulation study of\nfluid phase equilibria in highly size-asymmetrical binary mixtures. The method\nutilizes an expanded ensemble in which the insertion and deletion of large\nparticles is accomplished {\\em gradually} by traversing a series of states in\nwhich a large particle interacts only partially with the environment of small\nparticles. Free energy barriers arising from interfacial coexistence states are\nsurmounted with the aid of multicanonical preweighting, the associated weights\nbeing determined from the transition matrix. As an illustration, we present\nresults for the liquid-vapour coexistence properties of a Lennard-Jones binary\nmixture having a 10:1 size ratio.",
        "positive": "Intruder in a two-dimensional granular system: Effects of dynamic and\n  static basal friction on stick-slip and clogging dynamics: We discuss the results of simulations of an intruder pulled through a\ntwo-dimensional granular system by a spring, using a model designed to lend\ninsight into the experimental findings described by Kozlowski et al. [Phys.\nRev. E, 100, 032905 (2019)]. In that previous study the presence of basal\nfriction between the grains and the base was observed to change the intruder\ndynamics from clogging to stick-slip. Here we first show that our simulation\nresults are in excellent agreement with the experimental data for a variety of\nexperimentally accessible friction coefficients governing interactions of\nparticles with each other and with boundaries. Then, we use simulations to\nexplore a broader range of parameter space, focusing on the friction between\nthe particles and the base. We consider a range of both static and dynamic\nbasal friction coefficients, which are difficult to vary smoothly in\nexperiments. The simulations show that dynamic friction strongly affects the\nstick-slip behaviour when the coefficient is decreased below 0.1, while static\nfriction plays only a marginal role in the intruder dynamics."
    },
    {
        "anchor": "Monte Carlo Simulations of Lattice Models for Single Polymer Systems: Single linear polymer chains in dilute solutions under good solvent\nconditions are studied by Monte Carlo simulations with the pruned-enriched\nRosenbluth method up to the chain length $N \\sim {\\cal O}(10^4)$. Based on the\nstandard simple cubic lattice model (SCLM) with fixed bond length and the bond\nfluctuation model (BFM) with bond lengths in a range between $2$ and\n$\\sqrt{10}$, we investigate the conformations of polymer chains described by\nself-avoiding walks (SAWs) on the simple cubic lattice, and by random walks\n(RWs) and non-reversible random walks (NRRWs) in the absence of excluded volume\n(EV) interactions. In addition to flexible chains, we also extend our study to\nsemiflexible chains for different stiffness controlled by a bending potential.\nThe persistence lengths of chains extracted from the orientational correlations\nare estimated for all cases. We show that chains based on the BFM are more\nflexible than those based on the SCLM for a fixed bending energy. The\nmicroscopic differences between these two lattice models are discussed and the\ntheoretical predictions of scaling laws given in the literature are checked and\nverified. Our simulations clarify that a different mapping ratio between the\ncoarse-grained models and the atomistically realistic description of polymers\nis required in a coarse-graining approach due to the different crossovers to\nthe asymptotic behavior.",
        "positive": "Efficient dynamical correction of the transition state theory rate\n  estimate for a flat energy barrier: The recrossing correction to the transition state theory estimate of a\nthermal rate can be difficult to calculate when the energy barrier is flat.\nThis problem arises, for example, in polymer escape if the polymer is long\nenough to stretch between the initial and final state energy wells while the\npolymer beads undergo diffusive motion back and forth over the barrier. We\npresent an efficient method for evaluating the correction factor by\nconstructing a sequence of hyperplanes starting at the transition state and\ncalculating the probability that the system advances from one hyperplane to\nanother towards the product. This is analogous to what is done in forward flux\nsampling except that there the hyperplane sequence starts at the initial state.\nThe method is applied to the escape of polymers with up to 64 beads from a\npotential well. For high temperature, the results are compared with direct\nLangevin dynamics simulations as well as forward flux sampling and excellent\nagreement between the three rate estimates is found. The use of a sequence of\nhyperplanes in the evaluation of the recrossing correction speeds up the\ncalculation by an order of magnitude as compared with the traditional approach.\nAs the temperature is lowered, the direct Langevin dynamics simulations as well\nas the forward flux simulations become computationally too demanding, while the\nharmonic transition state theory estimate corrected for recrossings can be\ncalculated without significant increase in the computational effort."
    },
    {
        "anchor": "Probing the existence of phase transitions in one-dimensional fluids of\n  penetrable particles: Phase transitions in one-dimensional classical fluids are usually ruled out\nby making appeal to van Hove's theorem. A way to circumvent the conclusions of\nthe theorem is to consider an interparticle potential that is everywhere\nbounded. Such is the case of, {\\it e.g.}, the generalized exponential model of\nindex 4 (GEM-4 potential), which in three dimensions gives a reasonable\ndescription of the effective repulsion between flexible dendrimers in a\nsolution. An extensive Monte Carlo simulation of the one-dimensional GEM-4\nmodel [S. Prestipino, {\\em Phys. Rev. E} {\\bf 90}, 042306 (2014)] has recently\nprovided evidence of an infinite sequence of low-temperature cluster phases,\nhowever also suggesting that upon pushing the simulation forward what seemed a\ntrue transition may eventually prove to be only a sharp crossover. We hereby\ninvestigate this problem theoretically, by three different and increasingly\nsophisticated approaches ({\\it i.e.}, a mean-field theory, the transfer matrix\nof a lattice model of clusters, and the exact treatment of a system of point\nclusters in the continuum), to conclude that the alleged transitions of the\none-dimensional GEM4 system are likely just crossovers.",
        "positive": "Multiperiodic orbits from interacting soft spots in cyclically-sheared\n  amorphous solids: When an amorphous solid is deformed cyclically, it may reach a steady state\nin which the paths of constituent particles trace out closed loops that repeat\nin each driving cycle. A remarkable variant has been noticed in simulations\nwhere the period of particle motions is a multiple of the period of driving,\nbut the reasons for this behavior have remained unclear. Motivated by\nmesoscopic features of displacement fields in experiments on jammed solids, we\npropose and analyze a simple model of interacting soft spots -- locations where\nparticles rearrange under stress and that resemble two-level systems with\nhysteresis. We show that multiperiodic behavior can arise among just three or\nmore soft spots that interact with each other, but in all cases it requires\nfrustrated interactions, illuminating this otherwise elusive type of\ninteraction. We suggest directions for seeking this signature of frustration in\nexperiments and for achieving it in designed systems."
    },
    {
        "anchor": "On the growing length scale in a replica-coupled glassforming liquid: Computer simulations are used to study a three-dimensional polydisperse model\nglassformer in a replica-coupling setup where an attractive field $\\propto -\n\\varepsilon Q$ of strength $\\varepsilon$ can adjust the similarity of the\nsystem to a fixed reference configuration with the overlap parameter $Q$. The\npolydispersity in the model enables the efficient use of swap Monte Carlo in\ncombination with molecular-dynamics simulation from which we obtain fully\nequilibrated liquid configurations at very low temperature, i.e., far below the\ncritical temperature of mode-coupling theory, $T_{\\rm MCT}$. When the\n$\\varepsilon$-field is switched on, the fast dynamics with swaps allow\nrelaxation to the stationary state at temperatures below $T_{\\rm MCT}$. In the\nstationary state, the overlap $Q$ has a finite value that increases with\nincreasing $\\varepsilon$. For a given temperature $T$, fluctuations of the\noverlap around the average value become maximal at a critical field strength\n$\\varepsilon^\\star(T)$. With decreasing $T$ along this\n$\\varepsilon^\\star(T)$-line, overlap fluctuations increase and a transition\nfrom a unimodal overlap distribution to a bimodal shape occurs. We give\nevidence that these bimodal distributions are not due to first-order phase\ntransitions. However, they reflect finite-size effects due to a rapidly growing\nlength scale with decreasing temperature. We discuss the significance of this\nlength scale for the understanding of the glass transition.",
        "positive": "On quantum effects near the liquid-vapor transition in helium: The liquid-vapor transition in He-3 and He-4 is investigated by means of\npath-integral molecular dynamics and the quantum virial expansion. Both methods\nare applied to the critical isobar and the critical isochore. While previous\npath-integral simulations have mainly considered the lambda transition and\nsuperfluid regime in He-4, we focus on the vicinity of the critical point and\nobtain good agreement with experimental results for the molar volume and the\ninternal energy down to subcritical temperatures. We find that an effective\nclassical potential that properly describes the two-particle radial\ndistribution function exhibits a strong temperature dependence near the\ncritical temperature. This contrasts with the behavior of essentially classical\nsystems like xenon, where the effective potential is independent of\ntemperature. It is conjectured that, owing to this difference in behavior\nbetween classical and quantum-mechanical systems, the crossover behavior\nobserved for helium in the vicinity of the critical point differs qualitatively\nfrom that of other simple liquids."
    },
    {
        "anchor": "The Behavior of Granular Materials under Cyclic Shear: The design and development of a parallel plate shear cell for the study of\nlarge scale shear flows in granular materials is presented. The parallel plate\ngeometry allows for shear studies without the effects of curvature found in the\nmore common Couette experiments. A system of independently movable slats\ncreates a well with side walls that deform in response to the motions of grains\nwithin the pack. This allows for true parallel plate shear with minimal\ninterference from the containing geometry. The motions of the side walls also\nallow for a direct measurement of the velocity profile across the granular\npack. Results are presented for applying this system to the study of transients\nin granular shear and for shear-induced crystallization. Initial shear profiles\nare found to vary from packing to packing, ranging from a linear profile across\nthe entire system to an exponential decay with a width of approximately 6 bead\ndiameters. As the system is sheared, the velocity profile becomes much sharper,\nresembling an exponential decay with a width of roughly 3 bead diameters.\nFurther shearing produces velocity profiles which can no longer be fit to an\nexponential decay, but are better represented as a Gaussian decay or error\nfunction profile. Cyclic shear is found to produce large scale ordering of the\ngranular pack, which has a profound impact on the shear profile. There exist\nperiods of time in which there is slipping between layers as well as periods of\ntime in which the layered particles lock together resulting in very little\nrelative motion.",
        "positive": "Field Theory of Active Brownian Particles in Potentials: The Active Brownian Particle (ABP) model exemplifies a wide class of active\nmatter particles. In this work, we demonstrate how this model can be cast into\na field theory in both two and three dimensions. Our aim is manifold: we wish\nboth to extract useful features of the system, as well as to build a framework\nwhich can be used to study more complex systems involving ABPs, such as those\ninvolving interaction. Using the two-dimensional model as a template, we\ncalculate the mean squared displacement exactly, and the one-point density in\nan external potential perturbatively. We show how the effective diffusion\nconstant appears in the barometric density formula to leading order, and\ndetermine the corrections to it. We repeat the calculation in three dimensions,\nclearly a more challenging setup. Comparing different ways to capture the\nself-propulsion, we find that its perturbative treatment results in more\ntractable derivations without loss of exactness, where this is accessible."
    },
    {
        "anchor": "Fingering instabilities in binary granular systems: Fingering instabilities akin to the Rayleigh-Taylor (RT) instability in\nfluids have been observed in a binary granular system consisting of dense and\nsmall particles layered on top of lighter and larger particles, when the system\nis subjected to vertical vibration and fluidizing gas flow. Using observations\nfrom experiments and numerical modelling we explore whether the theory\ndeveloped to describe the Rayleigh-Taylor (RT) instability in fluids is also\napplicable to binary granular systems. Our results confirm the applicability of\nthe classic RT instability theory for binary granular systems demonstrating\nthat several key features are observed in both types of systems, viz: (i) The\ncharacteristic wavenumber of the instability is constant with time, (ii) the\namplitude of the characteristic wavenumber initially grows exponentially and\n(iii) the dispersion relation between the wavenumbers k of the interface\ninstability and the growth rates n(k) of their amplitudes holds in both\nfluid-fluid and binary granular systems. Our results also demonstrate that\ninter-particle friction is essential for the RT instability to occur in\ngranular media. For zero particle friction the interface instability bears a\ngreater resembles to the Richtmyer-Meshkov instability. We further define a\nyield criterion Y for the interface by treating the granular medium as a\nviscoplastic material; only for Y > 15 fingering occurs. Interestingly,\nprevious work has shown that instabilities in the Earth's lower mantle, another\nviscoplastic material, also occur for similar values of Y.",
        "positive": "Electron spin resonance investigation of Mn^{2+} ions and their dynamics\n  in manganese doped SrTiO_3: Using electron spin resonance, lattice position and dynamic properties of\nMn2+ ions were studied in 0.5 and 2 % manganese doped SrTiO3 ceramics prepared\nby conventional mixed oxide method. The measurements showed that Mn2+ ions\nsubstitute preferably up to 97 % for Sr if the ceramics is prepared with a\ndeficit of Sr ions. Motional narrowing of the Mn2+ ESR spectrum was observed\nwhen temperature increases from 120 K to 240-250 K that was explained as a\nmanifestation of off-center position of this ion at the Sr site. From the\nanalysis of the ESR spectra the activation energy Ea = 86 mV and frequency\nfactor 1/?0 ? (2-10)x10^(-14) 1/s for jumping of the impurity between\nsymmetrical off-center positions were determined. Both values are in agreement\nwith those derived previously from dielectric relaxation. This proves the\norigin of dielectric anomalies in SrTiO3:Mn as those produced by the\nreorientation dynamics of Mn2+ dipoles."
    },
    {
        "anchor": "Quasi-periodic and fractal polymers: Energy structure and carrier\n  transfer: We study the energy structure and the coherent transfer of an extra electron\nor hole along aperiodic polymers made of $N$ monomers, with fixed boundaries,\nusing B-DNA as our prototype system. We use a Tight-Binding wire model, where a\nsite is a monomer (e.g., in DNA, a base pair). We consider quasi-periodic\n(Fibonacci, Thue-Morse, Double-Period, Rudin-Shapiro) and fractal (Cantor Set,\nAsymmetric Cantor Set) polymers made of the same monomer (I polymers) or made\nof different monomers (D polymers). For all types of such polymers, we\ncalculate the HOMO and LUMO eigenspectrum, the HOMO-LUMO gap and the density of\nstates. We examine the mean over time probability to find the carrier at each\nmonomer, the frequency content of carrier transfer (Fourier spectra, weighted\nmean frequency of each monomer, total weighted mean frequency of the polymer),\nand the pure mean transfer rate $k$. Our results reveal that there is a\ncorrespondence between the degree of structural complexity and the transfer\nproperties. I polymers are more favorable for charge transfer than D polymers.\nWe compare $k(N)$ of quasi-periodic and fractal sequences with that of periodic\nsequences (including homopolymers) as well as with randomly shuffled sequences.\nFinally, we discuss aspects of experimental results on charge transfer rates in\nDNA with respect to our coherent pure mean transfer rates.",
        "positive": "Surface melting and crystallisation driven by sedimentation: a particle\n  resolved study: We investigate the effects of the reversal of the gravitational field onto a\nsedimented and partially crystallised suspension of nearly-hard sphere\ncolloids. We analyse the structural changes that take place during the melting\nof the crystalline regions and the reorganisation and assembly of the\nsedimenting particles. Through a comparison with numerical simulation, we\naccess the single-particle kinetics and identify the key structural mechanism\nin the competition between five-fold symmetric and cubic crystalline\nstructures. With the use of a coarse-grained, discrete model, we reproduce the\nkinetic network of reactions underpinning crystallisation and highlight the\nmain microscopic transitions."
    },
    {
        "anchor": "Colloidal electrophoresis: Scaling analysis, Green-Kubo relation, and\n  numerical results: We consider electrophoresis of a single charged colloidal particle in a\nfinite box with periodic boundary conditions, where added counterions and salt\nions ensure charge neutrality. A systematic rescaling of the electrokinetic\nequations allows us to identify a minimum set of suitable dimensionless\nparameters, which, within this theoretical framework, determine the reduced\nelectrophoretic mobility. It turns out that the salt-free case can, on the Mean\nField level, be described in terms of just three parameters. A fourth\nparameter, which had previously been identified on the basis of straightforward\ndimensional analysis, can only be important beyond Mean Field. More complicated\nbehavior is expected to arise when further ionic species are added. However,\nfor a certain parameter regime, we can demonstrate that the salt-free case can\nbe mapped onto a corresponding system containing additional salt. The\nGreen-Kubo formula for the electrophoretic mobility is derived, and its\nusefulness demonstrated by simulation data. Finally, we report on\nfinite-element solutions of the electrokinetic equations, using the commercial\nsoftware package COMSOL.",
        "positive": "Gas Bubbles and Gas Pancakes at Liquid/Solid Interface: A Continuum\n  Theory Incorporated with Molecular Interactions: The states of gas accumulated at the liquid-solid interface are analyzed\nbased on the continuum theory where the Hamaker constant is used to describe\nthe long-range interaction at the microscopic scale. The Hamaker constant is\nalways negative, whereas the gas spreading coefficient can be either sign.\nDespite the complexity of gas, including that the density profile may not be\nuniform due to absorption on both solid and liquid surfaces, we predict three\npossible gas states at the liquid-solid interface, i.e. complete wetting,\npartial wetting and pseudopartial wetting. These possible gas states correspond\nrespectively to a gas pancake (or film) surrounded by a wet solid, a gas bubble\nwith a finite contact angle, and a gas bubble(s) coexisting with a gas pancake.\nTypical thickness of the gas pancakes is at the nanoscale within the force\nrange of the long-range interaction, whereas the radius of the gas bubbles can\nbe large. The state of gas bubble(s) coexisting with a gas film is predicted\ntheoretically for the first time. Our theoretical results can contribute to the\ndevelopment of a unified picture of gas nucleation at the liquid-solid\ninterface."
    },
    {
        "anchor": "Peaked bulk crystal nucleation in charged sphere melts from salt\n  concentration dependent crystallization experiments at very low metastability: We determined bulk crystal nucleation rates in aqueous suspensions of charged\nspheres at low metastability. Experiments were performed in dependence on\nelectrolyte concen-tration and for two different particle number densities. The\ntime-dependent nucleation rate shows a pronounced initial peak, while\npost-solidification crystal size distributions are skewed towards larger\ncrystallite sizes. At each concentration, the nucleation rate density initially\ndrops exponentially with increasing salt concentration. The complete data set,\nhowever, shows an unexpected scaling of the nucleation rate densities with\nmet-astability times the number density of particles. Parameterization of our\nresults in terms of Classical Nucleation Theory reveals unusually low\ninterfacial free energies of the nu-cleus surfaces and nucleation barriers well\nbelow the thermal energy. We tentatively attribute our observations to the\npresence of doublets introduced by the employed con-ditioning technique and\nacting as nucleation seeds.",
        "positive": "Computational and Analytical Modeling of Cationic Lipid-DNA Complexes: We present a theoretical study of the physical properties of cationic\nlipid-DNA (CL-DNA) complexes - a promising synthetically based nonviral carrier\nof DNA for gene therapy. The study is based on a coarse-grained molecular\nmodel, which is used in Monte Carlo (MC) simulations of mesoscopically large\nsystems over time scales long enough to address experimental reality. In the\npresent work we focus on the statistical-mechanical behavior of lamellar\ncomplexes, which in MC simulations self-assemble spontaneously from a\ndisordered random initial state."
    },
    {
        "anchor": "Infinite Geometric Frustration in a Cubic Dipole Cluster: The geometric arrangement of interacting (magnetic) dipoles is a question of\nfundamental importance in physics, chemistry and engineering. Motivated by\nrecent progress concerning the self-assembly of magnetic structures, the\nequilibrium orientation of 8 interacting dipoles in a cubic cluster is\ninvestigated in detail. Instead of discrete equilibria we find a new type of\nground state consisting of infinitely many orientations. This continuum of\nenergetically degenerate states represents a yet unknown form of magnetic\nfrustration. The corresponding dipole rotations in the flat potential valley of\nthis Goldstone mode enable the construction of frictionless magnetic couplings.\nUsing novel computer-assisted algebraic geometry methods, we moreover\ncompletely enumerate all equilibrium configurations. The seemingly simple cubic\nsystem allows for exactly 9536 unstable discrete equilibria falling into 183\ndistinct energy families.",
        "positive": "How to Track Protists in Three Dimensions: We present an apparatus optimized for tracking swimming microorganisms in the\nsize range 10-1000 microns, in three dimensions (3D), far from surfaces, and\nwith negligible background convective fluid motion. CCD cameras attached to two\nlong working distance microscopes synchronously image the sample from two\nperpendicular directions, with narrowband dark-field or bright-field\nillumination chosen to avoid triggering a phototactic response. The images from\nthe two cameras can be combined to yield 3D tracks of the organism. Using\nadditional, highly directional broad-spectrum illumination with millisecond\ntiming control the phototactic trajectories in 3D of organisms ranging from\nChlamydomonas to Volvox can be studied in detail. Surface-mediated hydrodynamic\ninteractions can also be investigated without convective interference. Minimal\nmodifications to the apparatus allow for studies of chemotaxis and other taxes."
    },
    {
        "anchor": "Effect of self-propulsion on equilibrium clustering: In equilibrium, colloidal suspensions governed by short-range attractive and\nlong-range repulsive interactions form thermodynamically stable clusters. Using\nBrownian dynamics computer simulations, we investigate how this equilibrium\nclustering is affected when such particles are self-propelled. We find that the\nclustering process is stable under self-propulsion. For the range of\ninteraction parameters studied and at low particle density, the cluster size\nincreases with the speed of self-propulsion (activity) and for higher activity\nthe cluster size decreases, showing a non-monotonic variation of cluster size\nwith activity. This clustering behaviour is distinct from the pure kinetic (or\nmotility-induced) clustering of self-propelling particles which is observed at\nsignificantly higher activities and densities. We present an equilibrium model\nincorporating the effect of activity as activity-induced attraction and\nrepulsion by imposing that the strength of these interactions depend on\nactivity superlinearly. The model explains the cluster size dependence of\nactivity obtained from simulations semi-quantitatively. Our predictions are\nverifiable in experiments on interacting synthetic colloidal microswimmers",
        "positive": "Statistical properties of linear-hyperbranched graft copolymers prepared\n  via \"hypergrafting\" of AB_m monomers from linear B-functional core chains: A\n  Molecular Dynamics simulation: The reaction of $AB_m$ monomers (m=2,3) with a multifunctional B_f-type\npolymer chain (\"hypergrafting\") is studied by coarse-grained molecular dynamics\nsimulations. The $AB_m$ monomers are hypergrafted using the slow monomer\naddition strategy. Fully dendronized, i.e., perfectly branched polymers are\nalso simulated for comparison. The degree of branching DB of the molecules\nobtained with the \"hypergrafting\" process critically depends on the rate with\nwhich monomers attach to inner monomers compared to terminal monomers. This\nratio is more favorable if the $AB_m$ monomers have lower reactivity, since the\nfree monomers then have time to diffuse inside the chain. Configurational chain\nproperties are also determined, showing that the stretching of the polymer\nbackbone as a consequence of the \"hypergrafting\" procedure is much less\npronounced than for perfectly dendronized chains. Furthermore, we analyze the\nscaling of various quantities with molecular weight M for large M (M>100). The\nWiener index scales as $M^2.3$, which is intermediate between linear chains\n($M^3$) and perfectly branched polymers ($M^2 \\ln(M)$). The polymer size,\ncharacterized by the radius of gyration $R_g$ or the hydrodynamic radius $R_h$,\nis found to scale as $R_{g,h}~M^{\\nu}$ with $\\nu~0.38$, which lies between the\nexponent of diffusion limited aggregation ($\\nu=0.4$) and the mean-field\nexponent predicted by Konkolewicz and coworkers ($\\nu=0.33$)."
    },
    {
        "anchor": "Rigidity percolation in a random tensegrity via analytic graph theory: Functional structures from across the engineered and biological world combine\nrigid elements such as bones and columns with flexible ones such as cables,\nfibers and membranes. These structures are known loosely as tensegrities, since\nthese cable-like elements have the highly nonlinear property of supporting only\nextensile tension. Marginally rigid systems are of particular interest because\nthe number of structural constraints permits both flexible deformation and the\nsupport of external loads. We present a model system in which tensegrity\nelements are added at random to a regular backbone. This system can be solved\nanalytically via a directed graph theory, revealing a novel mechanical critical\npoint generalizing that of Maxwell. We show that even the addition of a few\ncable-like elements fundamentally modifies the nature of this transition point,\nas well as the later transition to a fully rigid structure. Moreover, the\ntensegrity network displays a fundamentally new collective avalanche behavior,\nin which the addition of a single cable leads to the elimination of multiple\nfloppy modes, a phenomenon that becomes dominant at the transition point. These\nphenomena have implications for systems with nonlinear mechanical constraints,\nfrom biopolymer networks to soft robots to jammed packings to origami sheets.",
        "positive": "Cross-link induced shrinkage of grafted Gaussian chains: The statistical mechanics of polymers grafted on surfaces has been the\nsubject of intense research activity because of many potential applications. In\nthis paper, we analytically investigate the conformational changes caused by a\nsingle cross-link on two ideal (Gaussian) chains grafted on a rigid planar\nsurface. Both the cross-link and the surface reduce the number of allowed\nconfigurations. In the absence of the hard substrate, the sole effect of the\ncross-link is a reduction in the effective Kuhn length of a tethered chain. The\ncross-link induced shrinkage (collapse) of the grafted chains (mushrooms) turns\nout to be a reduction in the variance of the distribution of the height of the\nchain rather than a reduction of the height itself."
    },
    {
        "anchor": "Pore-size dependence and slow relaxation of hydrogel friction on smooth\n  surfaces: Hydrogel consists of a crosslinked polymer matrix imbibed with a solvent such\nas water at volume fractions that can exceed 90\\%. They are important in many\nscientific and engineering applications due to their tunable physiochemical\nproperties, bio-compatibility, and ultra-low friction. Their multiphase\nstructure leads to a complex interfacial rheology, yet a detailed, microscopic\nunderstanding of hydrogel friction is still emerging. Using a custom-built\ntribometer, here we identify three distinct regimes of frictional behavior for\npolyacrylic acid (PAA), polyacrylamide (PAAm), and agarose hydrogel spheres on\nsmooth surfaces. We find that at low velocities, friction is controlled by\nhydrodynamic flow through the porous hydrogel network, and is inversely\nproportional to the characteristic pore size. At high velocities, a mesoscopic,\nlubricating liquid film forms between the gel and surface that obeys\nelastohydrodynamic theory. Between these regimes, the frictional force\ndecreases by an order of magnitude and displays slow relaxation over several\nminutes. Our results can be interpreted as an interfacial shear thinning of the\npolymers with an increasing relaxation time due to the confinement of\nentanglements. This transition can be tuned by varying the solvent salt\nconcentration, solvent viscosity, and sliding geometry at the interface.",
        "positive": "Chiral Separation by Flows: The Role of Flow Symmetry and Dimensionality: Separation of enantiomers by flows is a promising chiral resolution method\nusing cost-effective microfluidics. Notwithstanding a number of experimental\nand numerical studies, a fundamental understanding still remains elusive, and\nan important question as to whether it is possible to specify common physical\nproperties of flows that induce separation has not been addressed. Here, we\nstudy the separation of rigid chiral objects of an arbitrary shape induced by a\nlinear flow field at low Reynolds numbers. Based on a symmetry property under\nparity inversion, we show that the rate-of-strain field is essential to drift\nthe objects in opposite directions according to chirality. From eigenmode\nanalysis, we also derive an analytic expression for the separation conditions\nwhich shows that the flow field should be quasi-two-dimensional for the precise\nand efficient resolutions of microscopic enantiomers. We demonstrate this\nprediction by Langevin dynamics simulations with hydrodynamic interactions\nfully implemented. Finally, we discuss the practical feasibility of the linear\nflow analysis, considering separations by a vortex flow or an extensional flow\nunder a confining potential."
    },
    {
        "anchor": "Assessing the role of static lengthscales behind glassy dynamics in\n  polydisperse hard disks: The possible role of growing static order in the dynamical slowing down\ntowards the glass transition has recently attracted considerable attention. On\nthe basis of random first-order transition (RFOT) theory, a new method to\nmeasure the static correlation length of amorphous order, called \"point-to-set\n(PTS)\" length, has been proposed, and used to show that the dynamic length\ngrows much faster than the static length. Here we study the nature of the PTS\nlength, using a polydisperse hard disk system, which is a model that is known\nto exhibit a growing hexatic order upon densification. We show that the PTS\ncorrelation length is decoupled from the steeper increase of the correlation\nlength of hexatic order, while closely mirroring the decay length of two-body\ndensity correlations. Our results thus provide a clear example that other forms\nof order can play an important role in the slowing down of the dynamics,\ncasting a serious doubt on the order agnostic nature of the PTS length and its\nrelevance to slow dynamics, provided that a polydisperse hard disk system is a\ntypical glass former.",
        "positive": "Lees-Edwards boundary conditions for translation invariant shear flow:\n  implementation and transport properties: Molecular dynamics (MD) simulations represent a powerful investigation tool\nin the field of soft matter. By using shear flows, one can probe the bulk\nrheology of complex fluids, also beyond the linear response regime, in a way\nthat imitates laboratory experiments. One solution to impose a shear flow in\nparticle-based simulations is the Lees-Edwards technique which ensures that\nparticles experience shear by imposing rules for motion and interactions across\nthe boundary in the direction of the shear plane. Despite their presentation in\n1972, a readily available public implementation of Lees-Edwards boundary\nconditions has been missing from MD simulation codes. In this article, we\npresent our implementation of the Lees-Edwards technique and discuss the\nrelevant technical choices. We used ESPResSo, the extensible simulation package\nfor research on soft matter, for molecular dynamics simulations which can be\nused as a reference for other implementers. We illustrate our implementation\nusing bulk dissipative particle dynamics fluids, compare different viscosity\nmeasurement techniques, and observe the anomalous diffusion in our samples\nduring continuous and oscillatory shear, in good comparison to theoretical\nestimates."
    },
    {
        "anchor": "Mode-coupling theory for the slow collective dynamics of fluids adsorbed\n  in disordered porous media: We derive a mode-coupling theory for the slow dynamics of fluids confined in\ndisordered porous media represented by spherical particles randomly placed in\nspace. Its equations display the usual nonlinear structure met in this\ntheoretical framework, except for a linear contribution to the memory kernel\nwhich adds to the usual quadratic term. The coupling coefficients involve\nstructural quantities which are specific of fluids evolving in random\nenvironments and have expressions which are consistent with those found in\nrelated problems. Numerical solutions for two simple models with pure hard core\ninteractions lead to the prediction of a variety of glass transition scenarios,\nwhich are either continuous or discontinuous and include the possibility of\nhigher-order singularities and glass-glass transitions. The main features of\nthe dynamics in the two most generic cases are reviewed and illustrated with\ndetailed computations. Moreover, a reentry phenomenon is predicted in the low\nfluid-high matrix density regime and is interpreted as the signature of a\ndecorrelation mechanism by fluid-fluid collisions competing with the\nlocalization effect of the solid matrix.",
        "positive": "Tractionless Self-Propulsion of Active Drops: We report on a new mode of self-propulsion exhibited by compact drops of\nactive liquids on a substrate which, remarkably, is tractionless, i.e., which\nimparts no mechanical stress locally on the surface. We show, both analytically\nand by numerical simulation, that the equations of motion for an active nematic\ndrop possess a simple self-propelling solution, with no traction on the solid\nsurface and in which the direction of motion is controlled by the winding of\nthe nematic director field across the drop height. The physics underlying this\nmode of motion has the same origins as that giving rise to the zero viscosity\nobserved in bacterial suspensions. This topologically protected tractionless\nself-propusion provides a robust physical mechanism for efficient cell\nmigration in crowded environments like tissues."
    },
    {
        "anchor": "Surface tension of electrolytes: Hydrophilic and hydrophobic ions near\n  an interface: We calculate the ion distributions around an interface in fluid mixtures of\nhighly polar and less polar fluids (water and oil) for two and three ion\nspecies. We take into account the solvation and image interactions between ions\nand solvent. We show that hydrophilic and hydrophobic ions tend to undergo a\nmicrophase separation at an interface, giving rise to an enlarged electric\ndouble layer. We also derive a general expression for the surface tension of\nelectrolyte systems, which contains a negative electrostatic contribution\nproportional to the square root of the bulk salt density. The amplitude of this\nsquare-root term is small for hydrophilic ion pairs, but is much increased for\nhydrophilic and hydrophobic ion pairs. For three ion species including\nhydrophilic and hydrophobic ions, we calculate the ion distributions to explain\nthose obtained by x-ray reflectivity measurements.",
        "positive": "Immersed Cantilever Apparatus for Mechanics and Microscopy: We present here a novel cantilever based apparatus to perform translational\nstress or strain controlled rheology in very soft solids, and obtain\nsimultaneous confocal imaging of the 3 dimensional microstructure. The stress\nis measured using eddy based sensors. Both the stress and strain are controlled\nby applying PID control loops on measured quantities and changing position\nusing a micromanipulator. To get rid of surface tension forces, the sample and\ncantilever are immersed. This enables stress measurement and control down to\n3mPa. With this apparatus, we can independently apply shear and normal stress,\nor strain, with same precision. We demonstrate the technical capability of the\nsetup with steady shear strain or stress experiments on a soft protein gel\nsystem. The simultaneous confocal imaging offers insight into the macroscopic\nbreaking observed in an increasing shear strain experiment."
    },
    {
        "anchor": "Design of Toy Proteins Capable to Rearrange Conformations in a\n  Mechanical Fashion: We design toy protein mimicking a machine-like function of an enzyme. Using\nan insight gained by the study of conformation space of compact lattice\npolymers, we demonstrate the possibility of a large scale conformational\nrearrangement which occurs (i) without opening a compact state, and (ii) along\na linear (one-dimensional) path. We also demonstrate the possibility to extend\nsequence design method such that it yields a \"collective funnel\" landscape in\nwhich the toy protein (computationally) folds into the valley with\nrearrangement path at its bottom. Energies of the states along the path can be\ndesigned to be about equal, allowing for diffusion along the path. They can\nalso be designed to provide for a significant bias in one certain direction.\nTogether with a toy ligand molecule, our \"enzimatic\" machine can perform the\nentire cycle, including conformational relaxation in one direction upon ligand\nbinding and conformational relaxation in the opposite direction upon ligand\nrelease. This model, however schematic, should be useful as a test ground for\nphenomenological theories of machine-like properties of enzymes.",
        "positive": "Single vortex in a 2D optical lattices: The paper has been withdrawn due to technical reason."
    },
    {
        "anchor": "Microscopic and coarse-grained correlation functions in concentrated\n  dendrimer solutions: We employ monomer-resolved computer simulations of model dendrimer molecules,\nto examine the significance of many-body effects in concentrated solutions of\nthe same. In particular, we measure the radial distribution functions and the\nscattering functions between the centres of mass of the dissolved dendrimers at\nvarious concentrations, reaching values that slightly exceed the overlap\ndensity of the macromolecules. We analyse the role played by many-body\neffective interactions by comparing the structural data to those obtained by\napplying exclusively the previously obtained two-body effective interactions\nbetween the dendrimers [G{\\\"o}tze I O, Harreis H M and Likos C N 2004 {\\it J.\nChem. Phys.} {\\bf 120} 7761]. We find that the effects of the many-body forces\nare small in general and they become weaker as the dendrimer flexibility\nincreases. Moreover, we test the validity of the oft-used factorisation\napproximation to the total scattering intensity into a product of the form- and\nthe scattering factors, finding a breakdown of this factorisation at high\nconcentrations.",
        "positive": "Surface tension controls the onset of gyrification in brain organoids: Understanding the mechanics of brain embryogenesis can provide insights on\npathologies related to brain development, such as lissencephaly, a genetic\ndisease which cause a reduction of the number of cerebral sulci. Recent\nexperiments on brain organoids have confirmed that gyrification, i.e. the\nformation of the folded structures of the brain, is triggered by the\ninhomo-geneous growth of the peripheral region. However, the rheology of these\ncellular aggregates and the mechanics of lissencephaly are still matter of\ndebate. In this work, we develop a mathematical model of brain organoids based\non the theory of morpho-elasticity. We describe them as non-linear elastic\nbodies, composed of a disk surrounded by a growing layer called cortex. The\nexternal boundary is subjected to a tissue surface tension due the\nintercellular adhesion forces. We show that the resulting surface energy is\nrelevant at the small length scales of brain organoids and significantly\naffects the mechanics of cellular aggregates. We perform a linear stability\nanalysis of the radially symmetric configuration and we study the post-buckling\nbehaviour through finite element simulations. We find that the process of\ngyrification is triggered by the cortex growth and modulated by the competition\nbetween two length scales: the radius of the organoid and the capillary length\ndue to surface tension. We show that a solid model can reproduce the results of\nthe in-vitro experiments. Furthermore, we prove that the lack of brain sulci in\nlissencephaly is caused by a reduction of the cell stiffness: the softening of\nthe organoid strengthens the role of surface tension, delaying or even\ninhibiting the onset of a mechanical instability at the free boundary."
    },
    {
        "anchor": "Ultrasonic tracking of a sinking ball in a vibrated dense granular\n  suspension: Observing and understanding the movement of an intruder through opaque dense\nsuspensions such as quicksand remains a practical and conceptual challenge.\nHere we use an ultrasonic probe to investigate the dynamics of a steel ball\nsinking in a 3D dense glass bead packing saturated by water. We show that the\nfrictional model developed for dry granular media can be used to describe the\nball motion induced by horizontal vibration. From this rheology we infer the\nstatic friction coefficient and effective viscosity that decrease when\nincreasing the vibration intensity. Our main finding is that the\nvibration-induced reduction of the yield stress and increase of the sinking\ndepth are presumably due to induced slipping at the grain contacts but without\nvisible plastic rearrangements of grains, in contrast to dry granular packings.\nTo explain these results, we propose a mechanism of acoustic lubrication that\nreduces the inter-particle friction and leads to a decrease of the yield\nstress. This scenario is different from the mechanism of liquefaction usually\ninvoked in loosely packed quicksands where the vibration-induced compaction\nincreases the pore pressure and decreases the confining pressure on the solid\nskeleton, thus reducing the granular resistance to external load.",
        "positive": "Deformable and robust core-shell protein microcapsules templated by\n  liquid-liquid phase separated microdroplets: Microcapsules are a key class of microscale materials with applications in\nareas ranging from personal care to biomedicine, and with increasing potential\nto act as extracellular matrix (ECM) models of hollow organs or tissues. Such\ncapsules are conventionally generated from non-ECM materials including\nsynthetic polymers. Here, we fabricated robust microcapsules with controllable\nshell thickness from physically- and enzymatically-crosslinked gelatin and\nachieved a core-shell architecture by exploiting a liquid-liquid phase\nseparated aqueous dispersed phase system in a one-step microfluidic process.\nMicrofluidic mechanical testing revealed that the mechanical robustness of\nthicker-shell capsules could be controlled through modulation of the shell\nthickness. Furthermore, the microcapsules demonstrated\nenvironmentally-responsive deformation, including buckling by osmosis and\nexternal mechanical forces. A sequential release of cargo species was obtained\nthrough the degradation of the capsules. Stability measurements showed the\ncapsules were stable at 37 {\\deg}C for more than two weeks. Finally,\nall-aqueous liquid-liquid phase separated and multiphase liquid-liquid phase\nseparated systems were generated with the gel-sol transition of microgel\nprecursors. These smart capsules are promising models of hollow biostructures,\nmicroscale drug carriers, and building blocks or compartments for active soft\nmaterials and robots."
    },
    {
        "anchor": "Random Polyelectrolytes and Polyampholytes in Solution: The behavior of polyelectrolytes and polyampholytes in semi-dilute solutions\nis investigated theoretically. Various statistical charge distributions along\nthe polyelectrolyte chains are considered: smeared, annealed, permuted and\nquenched. Annealed polyampholytes are also considered. Path integral\nformulation was used to derive mean field free energies for the different\nmodels. Self-consistent field equation is obtained for the polymer order\nparameter and a Poisson-Boltzmann like equation for the electrostatic\npotential. The random phase approximation is used to calculate the\nmonomer-monomer structure factor S(q) for the different statistical charge\ndistribution models. We show that in the annealed model, fluctuations of the\nthe monomer charges contribute to the electrostatic screening in addition to\nthe free ions in the solution. The strength of this screening depends on the\nvariance of the monomer charge distribution and is especially important for\npolyampholytes in bad solvent conditions where the mesophase separation is\nenhanced. The ratio between the variance and the net average charge determines\nwhether polyampholytes behave as polyelectrolytes or as neutral chains.",
        "positive": "Cross-linked polymers in strain: Structure and anisotropic stress: Molecular dynamic simulation enables one to correlate the evolution of the\nmicro-structure with anisotropic stress when a material is subject to strain.\nThe anisotropic stress due to a constant strain-rate load in a cross-linked\npolymer is primarily dependent on the mean-square bond length and mean-square\nbond angle. Excluded volume interactions due to chain stacking and spatial\ndistribution also has a bearing on the stress response. The bond length\ndistribution along the chain is not uniform. Rather, the bond lengths at the\nend of the chains are larger and uniformly decrease towards the middle of the\nchain from both ends. The effect is due to the presence of cross-linkers. As\nwith linear polymers, at high density values, changes in mean-square bond\nlength dominates over changes in radius of gyration and end-to-end length. That\nis, bond deformations dominate over changes in size and shape. A large change\nin the mean-square bond length reflects in a jump in the stress response.\nShort-chain polymers more or less behave like rigid molecules. Temperature has\na peculiar effect on the response in the sense that even though bond lengths\nincrease with temperature, stress response decreases with increasing\ntemperature. This is due to the dominance of excluded volume effects which\nresult in lower stresses at higher temperatures. At low strain rates, some\nrelaxation in the bond stretch is observed from $\\epsilon=0.2$ to\n$\\epsilon=0.5$. At high strain rates, internal deformation of the chains\ndominate over their uncoiling leading to a rise in the stress levels."
    },
    {
        "anchor": "Confinement effects on the spatially inhomogeneous dynamics in metallic\n  glass films: We develop the Elastically Collective Nonlinear Langevin Equation theory to\ninvestigate, for the first time, glassy dynamics in capped metallic glass thin\nfilms. Finite-size effects on the spatial gradient of structural relaxation\ntime and glass transition temperature (Tg) are calculated at different\ntemperatures and vitrification criteria. Molecular dynamics is significantly\nslowed down near rough solid surfaces and the dynamics at location far from the\ninterfaces is sped up. In thick films, the mobility gradient normalized by the\nbulk value well obeys the double-exponential form since interference effects\nbetween two surfaces are weak. Reducing the film thickness induces a strong\ndynamic coupling between two surfaces and flattens the relaxation gradient. The\nnormalized gradient of the glass transition temperature is independent of\nvitrification timescale criterion and can be fitted by a superposition function\nas the films are not ultra-thin. The local fragility is found to remain\nunchanged with location. This finding suggests that one can use Angell plots of\nbulk relaxation time and the Tg spatial gradient to characterize glassy\ndynamics in metallic glass films. Our computational results agree well with\nexperimental data and simulation.",
        "positive": "Folding mechanisms at finite temperature: Folding mechanisms are zero elastic energy motions essential to the\ndeployment of origami, linkages, reconfigurable metamaterials and robotic\nstructures. In this paper, we determine the fate of folding mechanisms when\nsuch structures are miniaturized so that thermal fluctuations cannot be\nneglected. First, we identify geometric and topological design strategies aimed\nat minimizing undesired thermal energy barriers that generically obstruct\nkinematic mechanisms at the microscale. Our findings are illustrated in the\ncontext of a quasi one-dimensional linkage structure that harbors a\ntopologically protected mechanism. However, thermal fluctuations can also be\nexploited to deliberately lock a reconfigurable metamaterial into a fully\nexpanded configuration, a process reminiscent of order by disorder transitions\nin magnetic systems. We demonstrate that this effect leads certain topological\nmechanical structures to exhibit an abrupt change in the pressure -- a bulk\nsignature of the underlying topological invariant at finite temperature. We\nconclude with a discussion of anharmonic corrections and potential applications\nof our work to the the engineering of DNA origami devices and molecular robots."
    },
    {
        "anchor": "Self-assembled nematic colloidal motors powered by light: Biological motors are marvels of nature that inspire creation of their\nsynthetic counterparts with comparable nanoscale dimensions, high efficiency\nand diverse functions. Molecular motors have been synthesized, but obtaining\nnanomotors through self-assembly remains challenging. Here we describe a\nself-assembled colloidal motor with a repetitive light-driven rotation of\ntransparent micro-particles immersed in a liquid crystal and powered by a\ncontinuous exposure to unstructured ~1 nW light. A monolayer of azobenzene\nmolecules defines how the liquid crystal's optical axis mechanically couples to\nthe particle's surface, as well as how they jointly rotate as the light's\npolarization changes. The rotating particle twists the liquid crystal, which\nchanges polarization of traversing light. The resulting feedback mechanism\nyields a continuous opto-mechanical cycle and drives the unidirectional\nparticle spinning, with handedness and frequency robustly controlled by\npolarization and intensity of light. Our findings may lead to opto-mechanical\ndevices and colloidal machines compatible with liquid crystal display\ntechnology.",
        "positive": "Controlling stability and transport of magnetic microswimmers by an\n  external field: We investigate the hydrodynamic stability and transport of magnetic\nmicroswimmers in an external field using a kinetic theory framework. Combining\nlinear stability analysis and nonlinear 3D continuum simulations, we show that\nfor sufficiently large activity and magnetic field strengths, a homogeneous\npolar steady state is unstable for both puller and pusher swimmers. This\ninstability is caused by the amplification of anisotropic hydrodynamic\ninteractions due to the external alignment and leads to a partial\ndepolarization and a reduction of the average transport speed of the swimmers\nin the field direction. Notably, at higher field strengths a reentrant\nhydrodynamic stability emerges where the homogeneous polar state becomes stable\nand a transport efficiency identical to that of active particles without\nhydrodynamic interactions is restored."
    },
    {
        "anchor": "The spherical coordinate form of three-dimensional generalized dynamics\n  of soft-matter quasicrystals with 12-fold symmetry: This article reports the spherical coordinate form of three-dimensional\ngeneralized dynamics of soft-matter quasicrystals with 12-fold symmetry which\nprovides a basis for solving initial-boundary value problems of the equations\nunder some important cases. Some relevant solving methods are discussed as\nwell.",
        "positive": "Medium Amplitude Parallel Superposition (MAPS) Rheology of a Wormlike\n  Micellar Solution: The weakly nonlinear rheology of a surfactant solution of wormlike micelles\nis investigated from both a modeling and experimental perspective using the\nframework of medium amplitude parallel superposition (MAPS) rheology. MAPS\nrheology defines material functions, such as the third order complex\ncompliance, which span the entire weakly nonlinear response space of\nviscoelastic materials to simple shear deformations. Three-tone oscillatory\nshear deformations are applied to obtain feature-rich data characterizing the\nthird order complex compliance with high data throughput. Here, data for a\nCPyCl solution are compared to the analytical solution for the MAPS response of\na reptation-reaction constitutive model, which treats micelles as linear\npolymers that can break apart and recombine in solution. Regression of the data\nto the model predictions provides new insight into how these breakage and\nrecombination processes are affected by shear, and demonstrates the importance\nof using information-rich data to infer precise estimates of model parameters."
    },
    {
        "anchor": "The unified picture for the classical laws of Batschinski and the\n  rectilinear diameter for molecular fluids: The explicit relations between the thermodynamic functions of the Lattice Gas\nmodel and the fluid within the framework of approach proposed earlier in [V. L.\nKulinskii, J. Phys. Chem. B \\textbf{114} 2852 (2010)] are derived. It is shown\nthat the Widom line serves as the natural border between the gas-like and the\nliquid-like states of the fluid. The explanation of the global cubic form of\nthe binodal for the molecular liquids is proposed and the estimate for the\namplitude of the binodal opening is obtained.",
        "positive": "Transverse forces and glassy liquids in infinite dimensions: We explore the dynamics of a simple liquid whose particles, in addition to\nstandard potential-based interactions, are also subjected to transverse forces\npreserving the Boltzmann distribution. We derive the effective dynamics of one\nand two tracer particles in the infinite-dimensional limit. We determine the\namount of acceleration of the dynamics caused by the transverse forces, in\nparticular in the vicinity of the glass transition. We analyze the emergence\nand evolution of odd transport phenomena induced by the transverse forces."
    },
    {
        "anchor": "Ordering Kinetics of Canted and Uniform States in Nematic Liquid\n  Crystals: We undertake a comprehensive Monte Carlo (MC) study of the ordering kinetics\nin nematic liquid crystals (NLCs) in 3-dimensions $(d=3)$ by performing deep\nquenches from the isotropic $(T>T_c)$ to the nematic $(T<T_c)$ phase. The\ninter-molecular potential between the nematogens, represented by continuous\n$O(3)$ spins with inversion symmetry, is accurately mimicked by the {\\it\ngeneralised Lebwohl Lasher} (GLL) model. It incorporates second and fourth\norder Legendre interactions, and their relative interaction strength is\n$\\lambda$. For $\\lambda <-0.3$, we observe {\\it canted} morphologies with a\n$\\lambda$-dependent angle-of-tilt between the neighbouring rod-like molecules.\nFor $\\lambda \\geq-0.3$, the molecules align to yield {\\it uniform} states. The\ncoarsening morphologies obey {\\it generalized dynamical scaling} in the two\nregimes, but the scaling function is not robust with respect to $\\lambda$. The\nstructure factor tail in the canted regime follows the {\\it Porod law}:\n$S(k,t)\\sim k^{-4}$, implying that the coarsening dynamics is due to the\nannihilation of interfacial defects. This is unexpected, as the GLL model is\ncharacterised by a continuous order parameter. The uniform regime on the other\nhand, exhibits the expected {\\it generalized Porod decay}: $S(k,t)\\sim k^{-5}$,\ncharacteristic of scattering from {\\it string defects}. Finally, the domain\ngrowth obeys the {\\it Lifshitz-Allen-Cahn law}: $L(t)\\sim t^{1/2}$ for all\nvalues of $\\lambda$. Our results for the novel {\\it canted} regime are relevant\nfor a large class of systems with orientational ordering, e.g. active matter,\nmembranes, LC elastomers, etc. We hope that our work triggers-off stimulating\ninvestigations in them.",
        "positive": "Evolution of the force distributions in jammed packings of soft\n  particles: The evolution of the force distributions during the isotropic compression of\ntwo dimensional packings of soft frictional particles is investigated\nnumerically. Regardless of the applied deformation, the normal contact force\ndistribution can be fitted by the product of a power-law, and a stretched\nexponential, while the tangential force distribution is fitted well by a\nGaussian. With increasing strain, the asymptotic behavior at large forces does\nnot change, but both normal and tangential distributions exhibit a broadening,\neven though, when scaled with the average forces, their widths decrease.\nFurthermore, the distribution of friction mobilization is a decreasing function\nof the mobilization, except for an increased probability of fully mobilized\ncontacts. The excess coordination number of the packings increases with the\napplied strain, indicating that the more a packing is compressed the more\nstable it becomes."
    },
    {
        "anchor": "Modelling Mullins Effect Induced by Chain Delamination and Reattachment: We propose a continuum theory to model the Mullins effect, which is\nubiquitously observed in polymer composites. In the theory, the softening of\nthe materials during the stretching process is accounted for by considering the\ndelamination of polymer chains from nano-/micro-sized fillers, and the recovery\neffect during the de-stretching process is due to the reattachment of the\npolymer chains to nano-/micro-sized fillers. By incorporating the chain\nentanglements, Log-Normal distribution of the mesh size in the network, etc.,\nwe can obtain a good agreement between our numerical calculation results and\nexisting experimental data. This physical theory can be easily adapted to meet\nmore practical needs and utilised in analysing mechanic properties of polymer\ncomposites.",
        "positive": "Precessing vortex motion and instability in a rotating column of\n  superfluid 3He-B: The flow of quantized vortex lines in superfluid 3He-B is laminar at high\ntemperatures, but below 0.6 Tc turbulence becomes possible, owing to the\nrapidly decreasing mutual friction damping. In the turbulent regime a vortex\nevolving in applied flow may become unstable, create new vortices, and start\nturbulence. We monitor this single-vortex instability with NMR techniques in a\nrotating cylinder. Close to the onset temperature of turbulence, an oscillating\ncomponent in NMR absorption has been observed, while the instability generates\nnew vortices at a low rate ~ 1 vortex/s, before turbulence sets in. By\ncomparison to numerical calculations, we associate the oscillations with spiral\nvortex motion, when evolving vortices expand to rectilinear lines."
    },
    {
        "anchor": "Rheology of active fluids: This chapter on the rheology of active fluids is an attempt to correlate\ntheoretical and experimental work. A considerable amount of theoretical work\nand most of the experimental data focus on the rheology of active fluids in a\nNewtonian matrix, which displays uncommon macroscopic rheological behaviors,\nsuch as the apparent superfluid-like state of the pusher suspensions. The\nfailure of the \"scallop theorem\" for reciprocal swimmers in a non-Newtonian\nmatrix is highlighted. Finally, recent findings concerning the turbulent-like\nbehaviour in concentrated systems are described in detail.",
        "positive": "Self-similar and Universal Dynamics in Drainage of Mobile Soap Films: Vertical soap films drain under the influence of gravity, as indicated by the\ndownward motion of colorful horizontal interference fringes observed on their\nsurfaces. In this study conducted with rectangular soap films, we\nexperimentally characterize the descent dynamics of these isothickness fringes\nand report its self-similar nature. We also show that this result is equivalent\nto thickness profiles exhibiting a separation of space and time. By integrating\nnew measurements with data from the literature across various conditions, we\nvalidate these properties and establish the universality of the dynamics,\ngoverned by a single physical scalar. Our findings provide new insights for\nproposing a drainage model and understanding the mechanism of marginal\nregeneration at the origin of the process."
    },
    {
        "anchor": "Universal behaviour of the glass and the jamming transitions in finite\n  dimensions: We investigate the glass and the jamming transitions of hard spheres in\nfinite dimensions $d$, through a revised cell theory, that combines the free\nvolume and the Random First Order Theory (RFOT). Recent results show that in\ninfinite dimension the ideal glass transition and jamming transitions are\ndistinct, while based on our theory we argue that they indeed coincide for\nfinite $d$. As a consequence, jamming results into a percolation transition\ndescribed by RFOT, with a static length diverging with exponent $\\nu=2/d$,\nwhich we verify through finite size scaling, and standard critical exponents\n$\\alpha = 0$, $\\beta = 0$ and $\\gamma = 2$ independent on $d$.",
        "positive": "Phase transition oscillations induced by a strongly focused laser beam: We report here the observation of a surprising phenomenon consisting in a\noscillating phase transition which appears in a binary mixture,\nPMMA/3-octanone, when this is enlightened by a strongly focused infrared laser\nbeam. PMMA/3-octanone has a UCST (Upper Critical Solution Temperature) which\npresents a critical point at temperature Tc = 306.6 K and volume fraction\n$\\phi$c = 12.8 % [Crauste et al., ArXiv 1310.6720, 2012]. This oscillatory\nphenomenon appears because of thermophoretic and electrostriction effects and\nnon-linear diffusion. We analyze these oscillations and we propose a simple\nmodel which includes the minimal ingredients to produce the oscillatory\nbehavior. Phase transitions in binary mixtures are still a widely studied\nsubject, specifically near the critical point where several interesting and not\ncompletely understood phenomena may appear, among them we recall the critical\nCasimir forces [2],[3], confinement effects [4], [5] and out-of-equilibrium\ndynamics after a quench. The perturbation of the binary mixtures by mean of\nexternal fields is also an important and recent field of investigation [6]. For\nexample, a laser can induce interesting phenomena in demixing binary mixtures\nbecause the radiation pressure can deform the interface between the two phases\nand it can be used to measure the interface tension [7]. Depending on the\nnature of the binary mixtures, laser illumination can also lead to a mixing or\ndemixing transition. In ref.[8], focused infrared laser light heats the medium\ninitially in the homogeneous phase and causes a separation in the LCST (Low\nCritical Solution Temperature) system. The radiation pressure gradients in a\nlaser beam also contribute in the aggregation of polymers , thus producing a\nphase transition. The local heating may induce thermophoretic forces which\nattract towards the laser beam one of the binary-mixture components [9]. Other\nforces like electrostriction can also be involved [10]. In this letter, we\nreport a new phenomenon, which consists in an oscillating phase transition\ninduced by a constant illumination from an infrared laser beam in the\nheterogeneous region of an UCST (Upper Critical Solution Temperature) binary\nmixture. Oscillation phenomena in phase transition have already been reported\nin slow cooling UCST [11],[12] but as far as we know, never induced by a\nstationary laser illumination. After describing our experimental setup , we\nwill present the results. Then we will use a very simplified model which\ncontains the main necessary physical ingredients to induce this oscillation\nphenomenon."
    },
    {
        "anchor": "Deformation of a rotated granular pile governed by body-force-dependent\n  friction: Although the gravity dependence of granular friction is crucial to understand\nvarious natural phenomena, its precise characterization is difficult. We\npropose a method to characterize granular friction under various gravity (body\nforce) conditions controlled by centrifugal force; specifically, the\ndeformation of a rotated granular pile was measured. To understand the\nmechanics governing the observed nontrivial deformation of this pile, we\nintroduced an analytic model considering local force balance. The excellent\nagreement between the experimental data and theoretical model suggests that the\ndeformation is simply governed by the net body force (sum of gravity and\ncentrifugal force) and friction angle. The body-force dependence of granular\nfriction was precisely measured from the experimental results. The results\nreveal that the grain shape affects the degree of body-force dependence of the\ngranular friction.",
        "positive": "Experimental realization of the \"lock-and-key\" mechanism in liquid\n  crystals: The ability to control the movement and assembly of particles in liquid\ncrystals is not only an important route to design functional materials, but\nalso sheds light on the mechanisms of colloidal interactions. In this study we\nplace micron-sized particles with \"Saturn ring\" defects near a wall with hills\nand dales that impose perpendicular (homeotropic) molecular anchoring. The\nstrong splay distortion at the wall interacts with the distortion around the\nparticles in the near field and favors their migration towards the dales via\nthe so-called \"lock-and-key\" mechanism. We demonstrate experimentally that the\nlock-and-key mechanism can robustly localize a particle at specific\ntopographical features. We observe the complex trajectories traced by the\nparticles as they dock on the dales, estimate the binding energy, and explore a\nrange of parameters that favor or disfavor the docking event, thus exploiting\nthe capabilities of our experimental system. We extend the study to colloids\nwith homeotropic anchoring but with an associated point defect instead of a\nSaturn ring and show that they find a different preferred location, i.e. we can\nplace otherwise identical particles at well defined sites according to their\ntopological defect structure. Finally, for deep enough wells, confinement\ndrives topological transitions of Saturn rings to dipoles. This ability to\ntailor wall geometry to guide colloids to well defined sites within nematic\nliquid crystals represents an important new tool in directed assembly."
    },
    {
        "anchor": "Direct-space investigation of the ultraslow ballistic dynamics of a soft\n  glass: We use light microscopy to investigate the aging dynamics of a glass made of\nclosely packed soft spheres, following a rapid transition from a fluid to a\nsolid-like state. By measuring time-resolved, coarse-grained displacements\nfields, we identify two classes of dynamical events, corresponding to\nreversible and irreversible rearrangements, respectively. The reversible events\nare due to the small, experimentally unavoidable fluctuations of the\ntemperature imposed to the sample, leading to transient thermal expansions and\ncontractions that cause shear deformations. The irreversible events are plastic\nrearrangements, induced by the repeated shear cycles. We show that the\ndisplacement due to the irreversible rearrangements grows linearly with time,\nboth on average and at a local level. The velocity associated with this\nballistic motion decreases exponentially with sample age, accounting for the\nobserved slowing down of the dynamics. The displacement field due to the\nirreversible rearrangements has a vortex-like structure and is spatially\ncorrelated over surprisingly long distances.",
        "positive": "Periodic ordering of clusters in a one-dimensional lattice model: A generic lattice model for systems containing particles interacting with\nshort-range attraction long-range repulsion (SALR) potential that can be solved\nexactly in one dimension is introduced. We assume attraction J_1 between the\nfirst neighbors and repulsion J_2 between the third neighbors. The ground state\nof the model shows existence of two homogeneous phases (gas and liquid) for\nJ_2/J_1<1/3. In addition to the homogeneous phases, the third phase with\nperiodically distributed clusters appears for J_2/J_1>1/3. Phase diagrams\nobtained in the self-consistent mean-field approximation for a range of values\nof J_2/J_1 show very rich behavior, including reentrant melting, and\ncoexistence of two periodic phases (one with strong and the other one with weak\norder) terminated at a critical point. We present exact solutions for the\nequation of state as well as for the correlation function for characteristic\nvalues of J_2/J_1. Based on the exact results, for J_2/J_1>1/3 we predict\npseudo-phase transitions to the ordered cluster phase indicated by a rapid\nchange of density for a very narrow range of pressure, and by a very large\ncorrelation length for thermodynamic states where the periodic phase is stable\nin mean field. For 1/9<J_2/J_1<1/3 the correlation function decays\nmonotonically below certain temperature, whereas above this temperature\nexponentially damped oscillatory behavior is obtained. Thus, even though\nmacroscopic phase separation is energetically favored and appears for weak\nrepulsion at T=0, local spatial inhomogeneities appear for finite T. Monte\nCarlo simulations in canonical ensemble show that specific heat has a maximum\nfor low density \\rho that we associate with formation of living clusters, and\nif the repulsion is strong, another maximum for \\rho = 1/2."
    },
    {
        "anchor": "A Bouquet for Apollonius: Focal Conics in Sessile Cholesteric Droplets: Focal conic domains, are defects characteristic of layered liquid crystal\nphases. Their association can built flowers where petals are the ellipses of\nthe Dupin cyclides involved in these defect. We report here the observation of\nfocal conic flowers in cholesteric droplets sessile on a glass surface and\nsurrounded by glycerol. The observation of the droplets in different directions\nhelps to solve the 3D architecture of the flower. The effects of the droplet\nsize and of the pitch value are also reported.",
        "positive": "Granular bed consolidation, creep and armoring under subcritical fluid\n  flow: We show that a freshly sedimented granular bed settles and creeps forward\nover extended periods of time under an applied hydrodynamic shear stress, which\nis below the critical value for bedload transport. The rearrangements are found\nto last over a time scale which is millions of times the sedimentation time\nscale of a grain in the fluid. Compaction occurs uniformly throughout the bed,\nbut creep is observed to decay exponentially with depth, and decreases over\ntime. The granular volume fraction in the bed is found to increase\nlogarithmically, saturating at the random close packing value $\\phi_{rcp}\n\\approx 0.64$, while the surface roughness is observed to remain essentially\nunchanged. We demonstrate that an increasingly higher shear stress is required\nto erode the bed after a sub-critical shear is applied which results in an\nincrease in its volume fraction. Thus, we find that bed armoring occurs due to\na deep shear-induced relaxation of the bed towards the volume fraction\nassociated with the glass transition."
    },
    {
        "anchor": "The static structure factor of amorphous silicon and vitreous silica: Liquids are in thermal equilibrium and have a non-zero static structure\nfactor S(Q->0) = [<N^2>-<N>^2]/<N> = rho*k_B*T*Chi_T where rho is the number\ndensity, T is the temperature, Q is the scattering vector and Chi_T is the\nisothermal compressibility. The first part of this result involving the number\nN (or density) fluctuations is a purely geometrical result and does not involve\nany assumptions about thermal equilibrium or ergodicity and so is obeyed by all\nmaterials. From a large computer model of amorphous silicon, local number\nfluctuations extrapolate to give S(0) = 0.035+/-0.001. The same computation on\na large model of vitreous silica using only the silicon atoms and rescaling the\ndistances gives S(0) = 0.039+/-0.001, which suggests that this numerical result\nis robust and similar for all amorphous tetrahedral networks. For vitreous\nsilica, we find that S(0) = 0.116+/-0.003, close to the experimental value of\nS(0) = 0.0900+/-0.0048 obtained recently by small angle neutron scattering.\nMore detailed experimental and modelling studies are needed to determine the\nrelationship between the fictive temperature and structure.",
        "positive": "[N]pT ensemble and finite-size scaling study of the GEM-4 critical\n  isostructural transition: First-order transitions of system where both lattice site occupancy and\nlattice spacing fluctuate, such as cluster crystals, cannot be efficiently\nstudied by traditional simulation methods. These methods necessarily fix one of\nthese two degrees of freedom, but this difficulty is surmounted by the\ngeneralized [N]pT ensemble [J. Chem. Phys. 136, 214106 (2012)]. Here it is\nshown that histogram reweighting and the [N]pT ensemble can be used to study an\nisostructural transition between cluster crystals of different occupancy in the\ngeneralized exponential model of index 4 (GEM-4). Extending this scheme to\nfinite-size scaling studies also allows to accurately determine the critical\npoint parameters and to verify that it belongs to the Ising universality class."
    },
    {
        "anchor": "Clogging in bidirectional suspension flow: The sudden arrest of motion due to confinement is commonly observed via the\nclogging transition in the flow of particles through a constriction. We present\nresults of a simple experiment to elucidate a similar transition in the\nbidirectional flow of two species in which two species of macroscopic particles\nwith different densities are confined in a tube and suspended in a fluid of\nintermediate density. Counterflowing grains serve as mobile obstacles and\nclogging occurs without arch formation due to confinement. We measure the\nclogging or jamming probability $J$ as a function of number of particles of\neach species $N$ in a fixed channel length for channel widths $D = $ 3$-$7$d$,\nwhere $d$ is the particle diameter. $J(N)$ exhibits a sigmoidal dependence and\ncollapses on a single curve $J(N/D^3)$ indicating the transition occurs at a\ncritical density. Data is well-fit by a probabilistic model motivated by prior\nconstriction flows which assumes grains enter the clogging region with a fixed\nprobability to produce a clogging state. A quasi-two-dimensional experiment\nprovides insight into the interface shape and and we identify a Rayleigh-Taylor\ninstability at large channel widths.",
        "positive": "Cerenkov-like radiation in a binary Schr{\u00f6}dinger flow past an\n  obstacle: We consider the dynamics of two coupled miscible Bose-Einstein condensates,\nwhen an obstacle is dragged through them. The existence of two different speeds\nof sound provides the possibility for three dynamical regimes: when both\ncomponents are subcritical, we do not observe nucleation of coherent\nstructures; when both components are supercritical they both form dark solitons\nin one dimension (1D) and vortices or rotating vortex dipoles in two dimensions\n(2D); in the intermediate regime, we observe the nucleation of a structure in\nthe form of a dark-antidark soliton in 1D; subcritical component; the 2D analog\nof such a structure, a vortex-lump, is also observed."
    },
    {
        "anchor": "A System with Multiple Liquid-Liquid Critical Points: We study a three-dimensional system of particles interacting via\nspherically-symmetric pair potentials consisting of several discontinuous\nsteps. We show that at certain values of the parameters desribing the\npotential, the system has three first-order phase transitions between fluids of\ndifferent densities ending in three critical points.",
        "positive": "Dynamical behavior of microgels of Interpenetrated Polymer Networks: Microgel suspensions of Interpenetrated Polymer Network (IPN) of PNIPAM and\nPAAc in D$_2$O, have been investigated through dynamic light scattering as a\nfunction of temperature, pH and concentration across the Volume Phase\nTransition (VPT). The dynamics of the system is slowed down under H/D isotopic\nsubstitution due to the different balance between polymer/polymer and\npolymer/solvent interactions suggesting the crucial role played by H-bondings.\nThe swelling behavior, reduced with respect to PNIPAM and water, has been\ndescribed by the Flory-Rehner theory, tested for PNIPAM microgel and\nsuccessfully expanded to higher order for IPN microgels. Moreover the\nconcentration dependence of the relaxation time at neutral pH has highlighted\ntwo different routes to approach the glass transition: Arrhenius and\nsuper-Arrhenius (Vogel Fulcher Tammann) respectively below and above the VPT\nand a fragility plot has been derived. Fragility can be tuned by changing\ntemperature: across the VPT particles undergo a transition from soft-strong to\nstiff-fragile."
    },
    {
        "anchor": "Excitation of Faraday-like body waves in vibrated living earthworms: Biological cells and many living organisms are mostly made of liquids and\ntherefore, by analogy with liquid drops, they should exhibit a range of\nfundamental nonlinear phenomena such as the onset of standing surface waves.\nHere, we test four common species of earthworm to demonstrate that vertical\nvibration of living worms lying horizontally of a flat solid surface results in\nthe onset of subharmonic Faraday-like body waves, which is possible because\nearthworms have a hydrostatic skeleton with a flexible skin and a liquid-filled\nbody cavity. Our findings are supported by theoretical analysis based on a\nmodel of parametrically excited vibrations in liquid-filled elastic cylinders\nusing material parameters of the worm's body reported in the literature. The\nability to excite nonlinear subharmonic body waves in a living organism could\nbe used to probe, and potentially to control, important biophysical processes\nsuch as the propagation of nerve impulses, thereby opening up avenues for\naddressing biological questions of fundamental impact.",
        "positive": "Relaxation of interstitials in spherical colloidal crystals: Spherical colloidal crystals (CCs) self-assemble on the interface between two\nliquids. These 2D structures unconventionally combine local hexagonal order and\nspherical geometry. Nowadays CCs are actively studied by altering their\nstructures. However, the statistical analysis of such experiments results is\nlimited by uniqueness of self-assembled structures and their short lifetime.\nHere we perform numerical experiments to investigate pathways of CC structure\nrelaxation after the intrusion of interstitial. The process is simulated in the\nframes of overdamped molecular dynamics method. The relaxation occurs due to\ninteraction with extended topological defects (ETDs) mandatory induced in\nspherical CCs by their intrinsic Gaussian curvature. Types of relaxation\npathways are classified and their probabilities are estimated in the\nlow-temperature region. To analyze the structural changes during the relaxation\nwe use a parent phase approach allowing us to describe the global organization\nof spherical order. This organization is preserved by only the most typical\nrelaxation pathway resulting in filling one of vacancies integrated inside the\nETD areas. In contrast with this pathway the other ones shift the ETDs centers\nand can strongly reconstruct the internal structure of ETDs. Temperature\ndependence of the relaxation processes and the mechanism of dislocation\nunbinding are discussed. Common peculiarities in relaxation of spherical\nstructures and particular fragments of planar hexagonal lattice are found."
    },
    {
        "anchor": "Clusters, asters and collective oscillations in chemotactic colloids: The creation of synthetic systems that emulate the defining properties of\nliving matter, such as motility, gradient-sensing, signalling and replication,\nis a grand challenge of biomimetics. Such imitations of life crucially contain\nactive components that transform chemical energy into directed motion. These\nartificial realizations of motility point in the direction of a new paradigm in\nen- gineering, through the design of emergent behavior by manipulating\nproperties at the scale of the individual components. Catalytic colloidal\nswimmers are a particularly promising example of such systems. Here we present\na comprehensive theoretical description of gradient-sensing of an individual\nswimmer, leading controllably to chemotactic or anti-chemotactic behavior, and\nuse it to construct a framework for studying their collective behavior. We find\nthat both the positional and the orientational degrees of freedom of the active\ncolloids can exhibit condensation, signalling formation of clusters and asters.\nThe kinetics of catalysis introduces a natural control parameter for the range\nof the interaction mediated by the diffusing chemical species. For various\nregimes in parameter space in the long-ranged limit our system displays precise\nanalogs to gravitational collapse, plasma oscillations and electrostatic\nscreening. We present prescriptions for how to tune the surface properties of\nthe colloids during fabrication to achieve each type of behavior.",
        "positive": "Effects of cell elasticity on the migration behavior of a monolayer of\n  motile cells: Sharp Interface Model: In order to study the effect of cell elastic properties on the behavior of\nassemblies of motile cells, this paper describes an alternative to the cell\nphase field (CPF) \\cite{Palmieri2015} we have previously proposed. The CPF is a\nmulti-scale approach to simulating many cells which tracked individual cells\nand allowed for large deformations. Though results were largely in agreement\nwith experiment that focus on the migration of a soft cancer cell in a\nconfluent layer of normal cells \\cite{Lee2012}, simulations required large\ncomputing resources, making more detailed study unfeasible. In this work we\nderive a sharp interface limit of CPF, including all interactions and\nparameters. This new model offers over $200$ fold speedup when compared to our\noriginal CPF implementation. We demonstrate that this model captures similar\nbehavior and allows us to obtain new results that were previously intractable.\nWe obtain the full velocity distribution for a large range of degrees of\nconfluence, $\\rho$, and show regimes where its tail is heavier and lighter than\na normal distribution. Furthermore, we fully characterize the velocity\ndistribution with a single parameter, and its dependence on $\\rho$ is fully\ndetermined. Finally, cell motility is shown to linearly decrease with\nincreasing $\\rho$, consistent with previous theoretical results."
    },
    {
        "anchor": "A string reaction coordinate for the folding of a polymer chain: We investigate the crystallization mechanism of a single, flexible\nhomopolymer chain with short range attractions. For a sufficiently narrow\nattractive well, the system undergoes a first-order like freezing transition\nfrom an expanded disordered coil to a compact crystalline state. Based on a\nmaximum likelihood analysis of committor values computed for configurations\nobtained by Wang-Landau sampling, we construct a non-linear string reaction\ncoordinate for the coil-to-crystal transition. In contrast to a linear reaction\ncoordinate, the string reaction coordinate captures the effect of different\ndegrees of freedom controlling different stages of the transition. Our analysis\nindicates that a combination of the energy and the global crystallinity\nparameter Q6 provide the most accurate measure for the progress of the\ntransition. While the crystallinity parameter Q6 is most relevant in the\ninitial stages of the crystallization, the later stages are dominated by a\ndecrease in the potential energy.",
        "positive": "Two-Particle Microrheology of quasi-2D Viscous Systems: We study the correlated motions of colloidal particles in a quasi-2D system\n(Human Serum Albumin (HSA) protein molecules at an air-water interface) for\ndifferent surface viscosities $\\eta_{s}$. We observe a transition in the\nbehavior of the correlated motion, from 2-D interface dominated at high\n$\\eta_{s}$ to bulk fluid-dependent at low $\\eta_{s}$. The correlated motions\ncan be scaled onto a master curve which captures the features of this\ntransition. This master curve also characterizes the spatial dependence of the\nflow field of a viscous interface in response to a force. From the flow field\nand the correlated particle motions, we calculate a two-particle MSD (mean\nsquare displacement) for direct comparison with rheological measurements."
    },
    {
        "anchor": "A model of weak viscoelastic nematodynamics: The paper develops a continuum theory of weak viscoelastic nematodynamics of\nMaxwell type. It may describe the molecular elasticity effects in mono-domain\nflows of liquid crystalline polymers as well as the viscoelastic effects in\nsuspensions of uniaxially symmetric particles in polymer fluids. Along with\nviscoelastic and nematic kinematics, the theory employs a general form of\nweakly elastic thermodynamic potential and the Leslie-Ericksen-Parodi type\nconstitutive equations for viscous nematic liquids, while ignoring inertia\neffects and the Frank (orientation) elasticity in liquid crystal polymers. In\ngeneral case, even the simplest Maxwell model has many basic parameters.\nNevertheless, recently discovered algebraic properties of nematic operations\nreveal a general structure of the theory and present it in a simple form. It is\nshown that the evolution equation for director is also viscoelastic. An example\nof magnetization exemplifies the action of non-symmetric stresses. When the\nmagnetic field is absent, the theory is simplified to the symmetric, fluid\nmechanical case with relaxation properties for both the stress and director.\nOur recent analyses of elastic and viscous soft deformation modes are also\nextended to the viscoelastic case. The occurrence of possible soft modes\nminimizes both the free energy and dissipation, and also significantly\ndecreases the number of material parameters. In symmetric linear case, the\ntheory is explicitly presented in terms of anisotropic linear memory\nfunctionals. Several analytical results demonstrate a rich behavior predicted\nby the developed model for steady and unsteady flows in simple shearing and\nsimple elongation.",
        "positive": "When is a surface foam-phobic or foam-philic?: By integrating the Young-Laplace equation, including the effects of gravity,\nwe have calculated the equilibrium shape of the two-dimensional Plateau borders\nalong which a vertical soap film contacts two flat, horizontal solid substrates\nof given wettability. We show that the Plateau borders, where most of a foam's\nliquid resides, can only exist if the values of the Bond number ${\\rm Bo}$ and\nof the liquid contact angle $\\theta_c$ lie within certain domains in\n$(\\theta_c,{\\rm Bo})$ space: under these conditions the substrate is\nfoam-philic. For values outside these domains, the substrate cannot support a\nsoap film and is foam-phobic. In other words, on a substrate of a given\nwettability, only Plateau borders of a certain range of sizes can form. For\ngiven $(\\theta_c,{\\rm Bo})$, the top Plateau border can never have greater\nwidth or cross-sectional area than the bottom one. Moreover, the top Plateau\nborder cannot exist in a steady state for contact angles above 90$^\\circ$. Our\nconclusions are validated by comparison with both experimental and numerical\n(Surface Evolver) data. We conjecture that these results will hold, with slight\nmodifications, for non-planar soap films and bubbles. Our results are also\nrelevant to the motion of bubbles and foams in channels, where the friction\nforce of the substrate on the Plateau borders plays an important role."
    },
    {
        "anchor": "Effective stiffness and formation of secondary structures in a\n  protein-like model: We use Wang-Landau and replica exchange techniques to study the effect of an\nincreasing stiffness on the formation of secondary structures in protein-like\nsystems. Two possible models are considered. In both models, a polymer chain is\nformed by tethered beads where non-consecutive backbone beads attract each\nother via a square-well potential representing the tendency of the chain to\nfold. In addition, smaller hard spheres are attached to each non-terminal\nbackbone bead along the direction normal to the chain to mimic the steric\nhindrance of side chains in real proteins. The two models, however, differ in\nthe way bending rigidity is enforced. In the first model, partial overlap\nbetween consecutive beads is allowed. This reduces the possible bending angle\nbetween consecutive bonds thus producing an effective entropic stiffness that\ncompetes with a short-range attraction, and leads to a formation of secondary\nstructures characteristic of proteins. We discuss the low-temperature phase\ndiagram as a function of increasing interpenetration, and find a transition\nfrom a planar, beta-like structure, to helical shape. In the second model, an\nenergetic stiffness is explicitly introduced by imposing an infinitely large\nenergy penalty for bending above a critical angle between consecutive bonds,\nand no penalty below it. The low-temperature phase of this model does not show\nany sign of protein-like secondary structures. At intermediate temperatures,\nhowever, where the chain is still in the coil conformation but stiffness is\nsignificant, we find the two models to predict a quite similar dependence of\nthe persistence length as a function of the stiffness. This behaviour is\nrationalized in terms of a simple geometrical mapping between the two models.\nFinally, we discuss the effect of shrinking side chains to zero, and find the\nabove mapping to still hold true.",
        "positive": "Buckling of elastic filaments by discrete magnetic moments: We study the buckling of an idealized, semiflexible filament along whose\ncontour magnetic moments are placed. {We give analytic expressions for the\ncritical stiffness of the filament below which it buckles due to the magnetic\ncompression. For this, we consider various scenarios of the attachment of the\nmagnetic particles to the filament. One possible application for this model are\nthe magnetosome chains of magnetotactic bacteria. An estimate of the critical\nbending stiffness indicates that buckling may occur within the range of\nbiologically relevant parameters and suggests a role for the bending stiffness\nof the filament to stabilize the filament against buckling, which would\ncompromise the functional relevance of the bending stiffness of the used\nfilament."
    },
    {
        "anchor": "Ion-specificity in \u03b1-helical folding kinetics: The influence of the salts KCl, NaCl, and NaI at molar concentrations on the\n{\\alpha}-helical folding kinetics of the alanine-based oligopeptide\nAce-AEAAAKEAAAKA-Nme is investigated by means of (explicit-water) molecular\ndynamics simulations and a diffusional analysis. The mean first passage times\nfor folding and unfolding are found to be highly salt-specific. In particular,\nthe folding times increase about one order of magnitude for the sodium salts.\nThe drastic slowing down can be traced back to long-lived, compact\nconfigurations of the partially folded peptide, in which sodium ions are\ntightly bound by several carbonyl and carboxylate groups. This multiple\ntrapping is found to lead to a non-exponential residence time distribution of\nthe cations in the first solvation shell of the peptide. The analysis of\n{\\alpha}-helical folding in the framework of diffusion in a reduced\n(one-dimensional) free energy landscape further shows that the salt not only\nspecifically modifies equilibrium properties, but also induces kinetic barriers\ndue to individual ion binding. In the sodium salts, for instance, the peptide's\nconfigurational mobility (or \"diffusivity\") can decrease about one order of\nmagnitude. This study demonstrates the highly specific action of ions and\nhighlights the intimate coupling of intramolecular friction and solvent effects\nin protein folding.",
        "positive": "Set Voronoi Tessellation for Particulate Systems in Two Dimensions: Given a countable set of points in a continuous space, Voronoi tessellation\nis an intuitive way of partitioning the space according to the distance to the\nindividual points. As a powerful approach to obtain structural information, it\nhas a long history and widespread applications in diverse disciplines, from\nastronomy to urban planning. For particulate systems in real life, such as a\npile of sand or a crowd of pedestrians, the realization of Voronoi tessellation\nneeds to be modified to accommodate the fact that the particles cannot be\nsimply treated as points. Here, we elucidate the use of Set Voronoi\ntessellation (i.e., considering for a non-spherical particle a set of points on\nits surface) to extract meaningful local information in a quasi-two-dimensional\nsystem of granular rods. In addition, we illustrate how it can be applied to\narbitrarily shaped particles such as an assembly of honey bees or pedestrians\nfor obtaining structural information. Details on the implementation of this\nalgorithm with the strategy of balancing computational cost and accuracy are\ndiscussed. Furthermore, we provide our python code as open source in order to\nfacilitate Set Voronoi calculations in two dimensions for arbitrarily shaped\nobjects."
    },
    {
        "anchor": "Electrically assisted light-induced gliding of nematic liquid-crystal\n  easy axis at varying polarization azimuth of reorienting light: model and\n  experiment: The phenomenological torque balance model previously introduced to describe\nthe electrically assisted light-induced gliding is generalized to study the\nreorientation dynamics of the nematic liquid crystal easy axis at photoaligned\nazo-dye films under the combined action of in-plane electric field and\nreorienting UV light linearly polarized at varying polarization azimuth,\n$\\varphi_p$. We systematically examine the general properties of the torque\nbalance model by performing analysis of the bifurcations of equilibria at\ndifferent values of the polarization azimuth and apply the model to interpret\nthe experimental results. In our experiments, it is found that, in contrast to\nthe case where $\\varphi_p=0$ and the light polarization vector is parallel to\nthe initial easy axis, at $\\varphi_p\\ne 0$, the pronounced purely photoinduced\nreorientation occurs outside the interelectrode gaps. It is also observed that,\nin the regions between electrodes with non-zero electric field, the dynamics of\nreorientation slows down with $\\varphi_p$ and the sense of easy axis rotation\nis independent of the sign of $\\varphi_p$.",
        "positive": "Facilitated diffusion on confined DNA: In living cells, proteins combine 3D bulk diffusion and 1D sliding along the\nDNA to reach a target faster. This process is known as facilitated diffusion,\nand we investigate its dynamics in the physiologically relevant case of\nconfined DNA. The confining geometry and DNA elasticity are key parameters: we\nfind that facilitated diffusion is most efficient inside an isotropic volume,\nand on a flexible polymer. By considering the typical copy numbers of proteins\nin vivo, we show that the speedup due to sliding becomes insensitive to fine\ntuning of parameters, rendering facilitated diffusion a robust mechanism to\nspeed up intracellular diffusion-limited reactions. The parameter range we\nfocus on is relevant for in vitro systems and for facilitated diffusion on\nyeast chromatin."
    },
    {
        "anchor": "Monte Carlo Study of the Phase Structure of Compact Polymer Chains: We study the phase behavior of single homopolymers in a simple\nhydrophobic/hydrophilic off-lattice model with sequence independent local\ninteractions. The specific heat is, not unexpectedly, found to exhibit a\npronounced peak well below the collapse temperature, signalling a possible\nlow-temperature phase transition. The system size dependence at this maximum is\ninvestigated both with and without the local interactions, using chains with up\nto 50 monomers. The size dependence is found to be weak. The specific heat\nitself seems not to diverge. The homopolymer results are compared with those\nfor two non-uniform sequences. Our calculations are performed using the methods\nof simulated and parallel tempering. The performances of these algorithms are\ndiscussed, based on careful tests for a small system.",
        "positive": "Incorporating fluctuations and dynamics in self-consistent field\n  theories for polymer blends: We review various methods to investigate the statics and the dynamics of\ncollective composition fluctuations in dense polymer mixtures within\nfluctuating-field approaches. The central idea of fluctuating-field theories is\nto rewrite the partition function of the interacting multi-chain systems in\nterms of integrals over auxiliary, often complex, fields, which are introduced\nby means of appropriate Hubbard-Stratonovich transformations. Thermodynamic\naverages like the average composition and the structure factor can be expressed\nexactly as averages of these fields. We discuss different analytical and\nnumerical approaches to studying such a theory: The self-consistent field\napproach solves the integrals over the fluctuating fields in saddle-point\napproximation. Generalized random phase approximations allow to incorporate\nGaussian fluctuations around the saddle point. Field theoretical polymer\nsimulations are used to study the statistical mechanics of the full system with\nComplex Langevin or Monte Carlo methods. Unfortunately, they are hampered by\nthe presence of a sign problem. In dense system, the latter can be avoided\nwithout losing essential physics by invoking a saddle point approximation for\nthe complex field that couples to the total density. This leads to the external\npotential theory. We investigate the conditions under which this approximation\nis accurate. Finally, we discuss recent approaches to formulate realistic\ndynamical time evolution equations for such models. The methods are illustrated\nby two examples: A study of the fluctuation-induced formation of a polymeric\nmicroemulsion in a polymer-copolymer mixture, and a study of early-stage\nspinodal decomposition in a binary blend."
    },
    {
        "anchor": "Crossover from Jamming to Clogging Behaviors in Heterogeneous\n  Environments: Jamming describes a transition from a flowing or liquid state to a solid or\nrigid state in a loose assembly of particles such as grains or bubbles. In\ncontrast, clogging describes the ceasing of the flow of particulate matter\nthrough a bottleneck. It is not clear how to distinguish jamming from clogging,\nnor is it known whether they are distinct phenomena or fundamentally the same.\nWe examine an assembly of disks moving through a random obstacle array and\nidentify a transition from clogging to jamming behavior as the disk density\nincreases. The clogging transition has characteristics of an absorbing phase\ntransition, with the disks evolving into a heterogeneous phase-separated\nclogged state after a critical diverging transient time. In contrast, jamming\nis a rapid process in which the disks form a homogeneous motionless packing,\nwith a rigidity length scale that diverges as the jamming density is\napproached.",
        "positive": "Dendrimer Assisted Dispersion of Carbon Nanotubes: A Molecular Dynamics\n  Study: Various unique physical, chemical, mechanical and electronic properties of\ncarbon nanotube (CNT) make it very useful materials for diverse potential\napplication in many fields. Experimentally synthesized CNTs are generally found\nin bundle geometry with a mixture of different chirality and present a unique\nchallenge to separate them. In this paper we have proposed the PAMAM dendrimer\nto be an ideal candidate for this separation. To estimate efficiency of the\ndendrimer in dispersion of CNTs from the bundle geometry, we have calculated\npotential of mean forces (PMF). Our PMF study of two dendrimer wrapped CNTs\nshows lesser binding affinity compared to the two bare CNTs. PMF study shows\nthat the binding affinity decreases for non-protonated dendrimer and for the\nprotonated case, the interaction is fully repulsive in nature. For both the\nnon-protonated as well as protonated cases, the PMF increases with increasing\ndendrimer generations from 2 to 4 gradually compare to the bare PMF. We have\nperformed PMF calculations with (6,5) and (6,6) chirality to study the\nchirality dependence of PMF. Calculated PMF for protonated dendrimer wrapped\nchiral CNTs is more compared to the protonated dendrimer wrapped armchair CNTs\nfor all the generations studied. However, for non-protonated dendrimer wrapped\nCNTs such chirality dependence is not very prominent. Our study suggests that\nthe dispersion efficiency of protonated dendrimer is more compared to the\nnon-protonated dendrimer and can be used as an effective dispersing agent in\ndispersion of CNT from the bundle geometry."
    },
    {
        "anchor": "The Geometric Mean Squared Displacement and the Stokes-Einstein Scaling\n  in a Supercooled Liquid: It is proposed that the rate of relaxation in a liquid is better described by\nthe geometric mean of the van Hove distribution function, rather than the\nstandard arithmetic mean used to obtain the mean squared displacement. The\ndifference between the two means is shown to increase significantly with an\nincrease in the non-Gaussian character of the displacement distribution.\nPreliminary results indicate that the geometric diffusion constant results in a\nsubstantial reduction of the deviation from Stokes-Einstein scaling.",
        "positive": "Dynamics of the swelling or collapse of a homopolymer: We study the dynamics of a polymer when it is quenched from a $\\theta$\nsolvent into a good or bad solvent by means of a Langevin equation. The\nvariation of the radius of gyration is studied as a function of time. For the\nfirst stage of collapse or swelling, the characteristic time-scale is found to\nbe independent of the number of monomers. Other scaling laws are derived for\nthe diffusion regime at larger times. Although the present model is solved only\nfor homopolymers and doesn't include hydrodynamic interactions, these results\nmay be a first step towards the understanding of the early stages of protein\nfolding."
    },
    {
        "anchor": "The ABC of scale invariance at the level of action integrals, and the\n  software tool Kanon: A central and common aspect of renormalizable field theories is scale\ninvariance of the action integral. This note introduces the software tool\n\\emph{Kanon}, which allows to assemble arbitrary action integrals\ninteractively, and to determine their critical dimension and scale invariance.\nThe tool contains more than 60 well-known models with comments and references\nto the literature.",
        "positive": "Dielectric manipulation of polymer translocation dynamics in engineered\n  membrane nanopores: The alteration of the dielectric membrane properties by membrane engineering\ntechniques such as carbon nanotube (CNT) coating opens the way to novel\nmolecular transport strategies for biosensing purposes. In this article, we\npredict a macromolecular transport mechanism enabling the dielectric\nmanipulation of the polymer translocation dynamics in dielectric membrane pores\nconfining mixed electrolytes. In the giant permittivity regime of these\nengineered membranes governed by attractive polarization forces, multivalent\nions adsorbed by the membrane nanopore trigger a monovalent ion separation and\nset an electroosmotic counterion flow. The drag force exerted by this flow is\nsufficiently strong to suppress and invert the electrophoretic velocity of\nanionic polymers, and also to generate the mobility of neutral polymers whose\nspeed and direction can be solely adjusted by the charge and concentration of\nthe added multivalent ions. These features identify the dielectrically\ngenerated transport mechanism as an efficient mean to drive overall neutral or\nweakly charged analytes that cannot be controlled by an external voltage. We\nalso reveal that in anionic polymer translocation, multivalent cation addition\ninto the monovalent salt solution amplifies the electric current signal by\nseveral factors. The signal amplification is caused by the electrostatic\nmany-body interactions replacing the monovalent polymer counterions by the\nmultivalent cations of higher electric mobility. The strength of this\nelektrokinetic charge discrimination points out the potential of multivalent\nions as current amplifiers capable of providing boosted resolution in\nnanopore-based biosensing techniques."
    },
    {
        "anchor": "The Glassy Wormlike Chain: We introduce a new model for the dynamics of a wormlike chain in an\nenvironment that gives rise to a rough free energy landscape, which we baptise\nthe glassy wormlike chain. It is obtained from the common wormlike chain by an\nexponential stretching of the relaxation spectrum of its long-wavelength\neigenmodes, controlled by a single stretching parameter. Predictions for\npertinent observables such as the dynamic structure factor and the\nmicrorheological susceptibility exhibit the characteristics of soft glassy\nrheology and compare favourably with experimental data for reconstituted\ncytoskeletal networks and live cells. We speculate about the possible\nmicroscopic origin of the stretching, implications for the nonlinear rheology,\nand the potential physiological significance of our results.",
        "positive": "Maximum-entropy calculation of end-to-end distance distribution of force\n  stretching chains: Using the maximum-entropy method, we calculate the end-to-end distance\ndistribution of the force stretched chain from the moments of the distribution,\nwhich can be obtained from the extension-force curves recorded in\nsingle-molecule experiments. If one knows force expansion of the extension\nthrough the $(n-1)$th power of force, it is enough information to calculate the\n$n$ moments of the distribution. We examine the method with three force\nstretching chain models, Gaussian chain, free-joined chain and excluded-volume\nchain on two-dimension lattice. The method reconstructs all distributions\nprecisely. We also apply the method to force stretching complex chain\nmolecules: the hairpin and secondary structure conformations. We find that the\ndistributions of homogeneous chains of two conformations are very different:\nthere are two independent peaks in hairpin distribution; while only one peak is\nobserved in the distribution of secondary structure conformations. Our\ndiscussion also shows that the end-to-end distance distribution may discover\nmore critical physical information than the simpler extension-force curves can\ngive."
    },
    {
        "anchor": "A non-monotonic constitutive model is not necessary to obtain shear\n  banding phenomena in entangled polymer solutions: In 1975 Doi and Edwards predicted that entangled polymer melts and solutions\ncan have a constitutive instability, signified by a decreasing stress for shear\nrates greater than the inverse of the reptation time. Experiments did not\nsupport this, and more sophisticated theories incorporated Marrucci's idea\n(1996) of removing constraints by advection; this produced a monotonically\nincreasing stress and thus stable constitutive behavior. Recent experiments\nhave suggested that entangled polymer solutions may possess a constitutive\ninstability after all, and have led some workers to question the validity of\nexisting constitutive models. In this Letter we use a simple modern\nconstitutive model for entangled polymers, the non-stretching Rolie-Poly model\nwith an added solvent viscosity, and show that (1) instability and shear\nbanding is captured within this simple class of models; (2) shear banding\nphenomena is observable for weakly stable fluids in flow geometries that impose\na sufficiently inhomogeneous total shear stress; (3) transient phenomena can\npossess inhomogeneities that resemble shear banding, even for weakly stable\nfluids. Many of these results are model-independent.",
        "positive": "Multicomponent adhesive hard sphere models and short-ranged attractive\n  interactions in colloidal or micellar solutions: We investigate the dependence of the stickiness parameters $t_{ij}=1/(12\\tau\n_{ij})$ -- where the $\\tau_{ij}$ are the conventional Baxter parameters -- on\nthe solute diameters $\\sigma_{i}$ and $\\sigma_{j}$ in multicomponent sticky\nhard sphere (SHS) models for fluid mixtures of mesoscopic neutral particles. A\nvariety of simple but realistic interaction potentials, utilized in the\nliterature to model \\textit{short-ranged attractions} present in real solutions\nof colloids or reverse micelles, is reviewed. We consider: i) van der Waals\nattractions, ii) hard-sphere-depletion forces, iii) polymer-coated colloids,\niv) solvation effects (in particular hydrophobic bonding and attractions\nbetween reverse micelles of water-in-oil microemulsions). We map each of these\npotentials onto an equivalent SHS model, by requiring the equality of the\nsecond virial coefficients. The main finding is that, for most of the\npotentials considered, the size-dependence of $t_{ij}(T,\\sigma_{i},\\sigma\n_{j})$ can be approximated by essentially the same expression, i.e. a simple\npolynomial in the variable $\\sigma_{i}\\sigma_{j}/\\sigma_{ij}^{2}$, with\ncoefficients depending on the temperature $T$, or -- for depletion interactions\n-- on the packing fraction $\\eta_{0}$ of the depletant particles."
    },
    {
        "anchor": "Critical motility-induced phase separation belongs to the Ising\n  universality class: A collection of self-propelled particles with volume exclusion interactions\ncan exhibit the phenomenology of gas-liquid phase separation, known as\nmotility-induced phase separation (MIPS). The non-equilibrium nature of the\nsystem is fundamental to the phase transition, however, it is unclear whether\nMIPS at criticality contributes a novel universality class to non-equilibrium\nphysics. We demonstrate here that this is not the case by showing that a\ngeneric critical MIPS belongs to the Ising universality class with conservative\ndynamics.",
        "positive": "Intermediate-range order governs dynamics in dense colloidal liquids: The conventional wisdom is that liquids are completely disordered and lack\nnon-trivial structure beyond nearest-neighbor distances. Recent observations\nhave upended this view and demonstrated that the microstructure in liquids is\nsurprisingly rich and plays a critical role in numerous physical, biological,\nand industrial processes. However, approaches to uncover this structure are\neither system-specific or yield results that are not physically intuitive.\nHere, through single-particle resolved three-dimensional confocal microscope\nimaging and the use of a recently introduced four-point correlation function,\nwe show that bidisperse colloidal liquids have a highly non-trivial structure\ncomprising alternating layers with icosahedral and dodecahedral order, which\nextends well-beyond nearest-neighbor distances and grows with supercooling. By\nquantifying the dynamics of the system on the particle level, we establish that\nit is this intermediate-range order, and not the short-range order, which has a\none-to-one correlation with dynamical heterogeneities, a property directly\nrelated to the relaxation dynamics of glassy liquids. Our experimental findings\nprovide a direct and much sought-after link between the structure and dynamics\nof liquids and pave the way for probing the consequences of this\nintermediate-range order in other liquid state processes."
    },
    {
        "anchor": "The topological effect on the Mechanical properties of polymer knots: The mechanical properties of polymer knots under stretching in a bad or good\nsolvent are investigated by applying a given force $F$ to a point of the knot\nwhile keeping another point fixed. The Monte Carlo sampling of the polymer\nconformations on a simple cubic lattice is performed using a variant of the\nWang-Landau algorithm. The results of the calculations of the specific energy,\nspecific heat capacity and gyration radius for several knot topologies show a\ngeneral trend in the behavior of short polymer knots with lengths up to seventy\nlattice units. At low tensile force $F$, knots can be found either in a compact\nor an extended phase, depending if the temperature is low or high. At any\ntemperature, with increasing values of the force $F$, a polymer knot undergoes\na phase transition to a stretched state. This transition is characterized by a\nstrong peak in the heat capacity. There is also a minor peak, which corresponds\nto a transition occurring at low temperatures when the conformations of\npolymers in the stretched phase become swollen with increasing temperatures. It\nis also shown that the behavior of short polymer rings is strongly influenced\nby topological effects. The limitations in the number of accessible energy\nstates due to topological constraints is particularly evident in knots of small\nsize and such that their minimum number of crossing according to the Rolfsen\nknot table is high. An example is provided by a cinquefoil knot $5_1$ with a\nlength of only fifty lattice units. The thermal and mechanical properties of\nknots that can be represented with diagrams having the same minimum number of\ncrossings, are very similar. The size effects on the behavior of polymer knots\nhave been analyzed too. Surprisingly, it is found that topological effects fade\nout very fast with increasing polymer length.",
        "positive": "Crosslinking and depletion determine spatial instabilities in\n  cytoskeletal active matter: Active gels made of cytoskeletal proteins are valuable materials with\nattractive non-equilibrium properties such as spatial self-organization and\nself-propulsion. At least four typical routes to spatial patterning have been\nreported to date in different types of cytoskeletal active gels: bending and\nbuckling instabilities in extensile systems, and global and local contraction\ninstabilities in contractile gels. Here we report the observation of these four\ninstabilities in a single type of active gel and we show that they are\ncontrolled by two parameters: the concentrations of ATP and depletion agent. We\ndemonstrate that as the ATP concentration decreases, the concentration of\npassive motors increases until the gel undergoes a gelation transition. At this\npoint, buckling is selected against bending, while global contraction is\nfavored over local ones. Our observations are coherent with a hydrodynamic\nmodel of a viscoelastic active gel where the filaments are crosslinked with a\ncharacteristic time that diverges as the ATP concentration decreases. Our work\nthus provides a unified view of spatial instabilities in cytoskeletal active\nmatter."
    },
    {
        "anchor": "Geometric theory on the elasticity of bio-membranes: The purpose of this paper is to study the shapes and stabilities of\nbio-membranes within the framework of exterior differential forms. After a\nbrief review of the current status in theoretical and experimental studies on\nthe shapes of bio-membranes, a geometric scheme is proposed to discuss the\nshape equation of closed lipid bilayers, the shape equation and boundary\nconditions of open lipid bilayers and two-component membranes, the shape\nequation and in-plane strain equations of cell membranes with cross-linking\nstructures, and the stabilities of closed lipid bilayers and cell membranes.\nThe key point of this scheme is to deal with the variational problems on the\nsurfaces embedded in three-dimensional Euclidean space by using exterior\ndifferential forms.",
        "positive": "Suppression of the rate of growth of dynamic heterogeneities and its\n  relation to the local structure in a supercooled polydisperse liquid: The relationship between the microscopic arrangement of molecules in a\nsupercooled liquid and its slow dynamics at low temperature near glass\ntransition is studied by Molecular Dynamics (MD) simulations. A Lennard-Jones\nliquid with polydispersity in size and mass of constituent particles is chosen\nas the model system. Our studies reveal that the local structure (that varies\nwith polydispersity) plays a crucial role both in the slowing down of dynamics\nand in the growth of the dynamic heterogeneities, besides determining the glass\nforming ability (GFA) of the system. Increasing polydispersity at fixed volume\nfraction is found to suppress the rate of growth of dynamic correlations, as\ndetected by the growth in the peak of the non-linear density response function.\nThe growth in dynamical correlation is manifested in a stronger than usual\nbreakdown of Stokes-Einstein relation at lower polydispersity at low\ntemperatures and also leads to a decrease in the fragility of the system with\npolydispersity. We show that the suppression of the rate of growth of the\ndynamic heterogeneity can be attributed to the loss of structural correlations\n(as measured by the structure factor and the local bond orientational order)\nwith polydispersity. While a critical polydispersity is required to avoid\ncrystallization, we find that further increase in polydispersity lowers the\nglass forming ability (GFA)."
    },
    {
        "anchor": "Equation of state for hard square lattice gases: A simple equation of state for a lattice gas of hard squares of side length\n$\\lambda$ is presented. Comparing to the Monte Carlo simulations, the new\nequation of state is found to be quite accurate for the disordered fluid phase.",
        "positive": "Diffusion-based height analysis reveals robust microswimmer-wall\n  separation: Microswimmers typically move near walls, which can strongly influence their\nmotion. However, direct experimental measurements of swimmer-wall separation\nremain elusive to date. Here, we determine this separation for model catalytic\nmicroswimmers from the height dependence of the passive component of their\nmean-squared displacement. We find that swimmers exhibit \"ypsotaxis\", a\ntendency to assume a fixed height above the wall for a range of salt\nconcentrations, swimmer surface charges, and swimmer sizes. Our findings\nindicate that ypsotaxis is activity-induced, posing restrictions on future\nmodeling of their still debated propulsion mechanism."
    },
    {
        "anchor": "Origins of complexity in the rheology of Soft Earth suspensions: When wet soil becomes fully saturated by intense rainfall, or is shaken by an\nearthquake, it may fluidize catastrophically. Sand-rich slurries are treated as\ngranular suspensions, where failure is related to an unjamming transition and\nfriction is controlled by particle concentration and pore pressure. Mud flows\nare modeled as complex fluids akin to gels, where yielding and shear-thinning\nbehaviors arise from inter-particle attraction and clustering. Here we show\nthat the full range of complex flow behaviors previously reported for natural\ndebris flows - dense slurries of soil and water - can be reproduced with\nsuspensions made only of water, sand and clay. Going from sand-rich to\nclay-rich suspensions, we observe a continuous transition from brittle\n(Coulomb-like) to ductile (perfect plastic) yielding that is characterized by\n(i) a decrease in the stress drop associated with yielding, (ii) an increase in\nthe shear-thinning exponent from zero to 1/2, and (iii) a decrease in the\nnormal force. We propose a general constitutive relation for soil suspensions,\nwith a particle rearrangement time that is controlled by yield stress. Our\nexperimental results are supported by models for yielding of idealized\namorphous solids, suggesting that the paradigm of non-equilibrium phase\ntransitions can help to understand and even predict complex behaviors of Soft\nEarth suspensions.",
        "positive": "Ground-state correlation energy of counterions at a charged planar wall:\n  Gibbs-Bogoliubov lower-bound approach: Recent simulation results imply the lowering of the ground-state correlation\nenergy per counterion at a charged planar wall, compared with that of the 2D\nand 3D one-component plasma systems. Our aim is to correctly evaluate the\nground-state energy of strongly-coupled counterion systems by considering a\nquasi-2D bound state where bound counterions are confined to a layer of\nmolecular thickness. We use a variational approach based on the\nGibbs-Bogoliubov inequality for the lower-bound free energy so that the\nliquid-state theory can be incorporated into the formulations. The soft mean\nspherical approximation demonstrates that the lowered ground-state energy can\nbe reproduced by the obtained analytical form of a quasi-2D bound state."
    },
    {
        "anchor": "Using neural networks to predict icephobic performance: Icephobic surfaces inspired by superhydrophobic surfaces offer a passive\nsolution to the problem of icing. However, modeling icephobicity is challenging\nbecause some material features that aid superhydrophobicity can adversely\naffect the icephobic performance. This study presents a new approach based on\nartificial neural networks to model icephobicity. Artificial neural network\nmodels were developed to predict the icephobic performance of concrete. The\nmodels were trained on experimental data to predict the surface ice adhesion\nstrength and the coefficient of restitution (COR) of water droplet bouncing off\nthe surface under freezing conditions. The material and coating compositions,\nand environmental condition were used as the models' input variables. A\nmultilayer perceptron was trained to predict COR with a root mean squared error\nof 0.08, and a 90% confidence interval of [0.042, 0.151]. The model had a\ncoefficient of determination of 0.92 after deployment. Since ice adhesion\nstrength varied over a wide range of values for the samples, a mixture density\nnetwork was model was developed to learn the underlying relationship in the\nmultimodal data. Coefficient of determination for the model was 0.96. The\nrelative importance of the input variables in icephobic performance were\ncalculated using permutation importance. The developed models will be\nbeneficial to optimize icephobicity of concrete.",
        "positive": "Rational design of self-assembly pathways for complex multicomponent\n  structures: The field of complex self-assembly is moving toward the design of\nmulti-particle structures consisting of thousands of distinct building blocks.\nTo exploit the potential benefits of structures with such `addressable\ncomplexity,' we need to understand the factors that optimize the yield and the\nkinetics of self-assembly. Here we use a simple theoretical method to explain\nthe key features responsible for the unexpected success of DNA-brick\nexperiments, which are currently the only demonstration of reliable\nself-assembly with such a large number of components. Simulations confirm that\nour theory accurately predicts the narrow temperature window in which\nerror-free assembly can occur. Even more strikingly, our theory predicts that\ncorrect assembly of the complete structure may require a time-dependent\nexperimental protocol. Furthermore, we predict that low coordination numbers\nresult in non-classical nucleation behavior, which we find to be essential for\nachieving optimal nucleation kinetics under mild growth conditions. We also\nshow that, rather surprisingly, the use of heterogeneous bond energies improves\nthe nucleation kinetics and in fact appears to be necessary for assembling\ncertain intricate three-dimensional structures. This observation makes it\npossible to sculpt nucleation pathways by tuning the distribution of\ninteraction strengths. These insights not only suggest how to improve the\ndesign of structures based on DNA bricks, but also point the way toward the\ncreation of a much wider class of chemical or colloidal structures with\naddressable complexity."
    },
    {
        "anchor": "Controlling motile disclinations in a thick nematogenic material with an\n  electric field: Manipulating topological disclination networks that arise in a\nsymmetry-breaking phase transfor- mation in widely varied systems including\nanisotropic materials can potentially lead to the design of novel materials\nlike conductive microwires, self-assembled resonators, and active anisotropic\nmatter. However, progress in this direction is hindered by a lack of control of\nthe kinetics and microstructure due to inherent complexity arising from\ncompeting energy and topology. We have studied thermal and electrokinetic\neffects on disclinations in a three-dimensional nonabsorbing nematic material\nwith a positive and negative sign of the dielectric anisotropy. The electric\nflux lines are highly non-uniform in uniaxial media after an electric field\nbelow the Fr\\'eedericksz threshold is switched on, and the kinetics of the\ndisclination lines is slowed down. In biaxial media, depending on the sign of\nthe dielectric anisotropy, apart from the slowing down of the disclination\nkinetics, a non-uniform electric field filters out disclinations of different\ntopology by inducing a kinetic asymmetry. These results enhance the current\nunderstanding of forced disclination networks and establish the pre- sented\nmethod, which we call fluctuating electronematics, as a potentially useful tool\nfor designing materials with novel properties in silico.",
        "positive": "Revisiting the Concept of Activation in Supercooled Liquids: In this work we revisit the description of dynamics based on the concepts of\nmetabasins and activation in mildly supercooled liquids via the analysis of the\ndynamics of a paradigmatic glass former between its onset temperature $T_{o}$\nand mode-coupling temperature $T_{c}$. First, we provide measures that\ndemonstrate that the onset of glassiness is indeed connected to the landscape,\nand that metabasin waiting time distributions are so broad that the system can\nremain stuck in a metabasin for times that exceed $\\tau_\\alpha$ by orders of\nmagnitude. We then reanalyze the transitions between metabasins, providing\nseveral indications that the standard picture of activated dynamics in terms of\ntraps does not hold in this regime. Instead, we propose that here activation is\nprincipally driven by entropic instead of energetic barriers. In particular, we\nillustrate that activation is not controlled by the hopping of high energetic\nbarriers, and should more properly be interpreted as the entropic selection of\nnearly barrierless but rare pathways connecting metabasins on the landscape."
    },
    {
        "anchor": "Assembling patchy plasmonic nanoparticles with aggregation-dependent\n  antibacterial activity: We realise an antibacterial nanomaterial based on the self-limited assembly\nof patchy plasmonic colloids, obtained by adsorption of lysozyme to gold\nnanoparticles. The possibility of selecting the size of the assemblies within\nseveral hundred nanometres allows for tuning their optical response in a wide\nrange of frequencies from visible to near infrared. We also demonstrate an\naggregation-dependent modulation of the catalytic activity, which results in an\nenhancement of the antibacterial performances for assemblies of the proper\nsize. The gained overall control on structure, optical properties and\nbiological activity of such nanomaterial paves the way for the development of\nnovel antibacterial nanozymes with promising applications in treating multi\ndrug resistant bacteria.",
        "positive": "Josephson Current Flowing in Cyclically Coupled Bose-Einstein\n  Condensates: The Josephson effect in cyclically coupled Bose-Einstein condensates is\nstudied theoretically. We analyze the simultaneous Gross-Pitaevskii equations\nwith coupling terms between adjacent condensates. Depending on the initial\nrelative phases between condensates, Josephson current flows cyclically to make\na quantized vortex. Reducing the coupling between condensates changes the\nmotion from periodic to chaotic, thus suppressing the cyclic current. The\nrelation to the Kibble-Zurek mechanism is discussed."
    },
    {
        "anchor": "Molecular mechanisms of self-mated hydrogel friction: Self-mated hydrogel contacts show extremely small friction coefficients at\nlow loads but a distinct velocity dependence. Here we combine mesoscopic\nsimulations and experiments to test the polymer-relaxation hypothesis for this\nvelocity dependence, where a velocity-dependent regime emerges when the\nperturbation of interfacial polymer chains occurs faster than their relaxation\nat high velocity. Our simulations reproduce the experimental findings, with\nspeed-independent friction at low velocity, followed by a friction coefficient\nthat rises with velocity to some power of order unity. We show that the\nvelocity-dependent regime is characterized by reorientation and stretching of\npolymer chains in the direction of shear, leading to an entropic stress that\ncan be quantitatively related to the shear response. The detailed exponent of\nthe power law in the velocity dependent regime depends on how chains interact:\nWe observe a power close to $1/2$ for chains that can stretch, while pure\nreorientation leads to a power of unity. Our simulations quantitatively match\nexperiments and show that the velocity dependence of hydrogel friction at low\nloads can be firmly traced back to the morphology of near-surface chains.",
        "positive": "Polyelectrolyte Polypeptide Scaling Laws Via Mechanical and Dielectric\n  Relaxation Measurements: Experimental results from mechanical viscoelastic as well as dielectric\nrelaxation times were compared to theoretical expectations utilizing polymer\nscaling theory. Viscoelastic relaxation of a hydrogel at 33% relative humidity\nfabricated from co-poly-L-(glutamic acid$_{4}$, tyrosine$_{1}$) [PLEY(4:1)]\ncrosslinked with poly-L-lysine scaled with concentration according to reptation\ndynamics. High frequency dielectric relaxation of aqueous copolymer PLEY(4:1)\nscaled with concentration as an ideal chain and aqueous Poly-L-glutamic acid\nscaled as an extended chain. The study shows that two seemingly different\nmeasurement methods can yield information about the state of polymer chain\nconformation in situ."
    },
    {
        "anchor": "De Vries Behavior in Smectics near a Biaxiality Induced Smectic A -\n  Smectic C Tricritical Point: We show that a generalized Landau theory for the smectic A and C phases\nexhibits a biaxiality induced AC tricritical point. Proximity to this\ntricritical point depends on the degree of orientational order in the system;\nfor sufficiently large orientational order the AC transition is 3D XY-like,\nwhile for sufficiently small orientational order, it is either tricritical or\n1st order. We investigate each of the three types of AC transitions near\ntricriticality and show that for each type of transition, small orientational\norder implies de Vries behavior in the layer spacing, an unusually small layer\ncontraction. This result is consistent with, and can be understood in terms of,\nthe \"diffuse cone\" model of de Vries. Additionally, we show that birefringence\ngrows upon entry to the C phase. For a continuous transition, this growth is\nmore rapid the closer the transition is to tricriticality. Our model also\npredicts the possibility of a nonmontonic temperature dependence of\nbirefringence.",
        "positive": "Shear zones in granular mixtures of hard and soft particles with high\n  and low friction: Granular materials show inhomogeneous flows characterized by strain\nlocalization. When strain is localized in a sheared granular material, rigid\nregions of a nearly undeformed state are separated by shear bands, where the\nmaterial yields and flows. The characteristics of the shear bands are\ndetermined by the geometry of the system, the micromechanical material\nproperties, and the kinematics at the particle level. For a split-bottom shear\ncell, recent experimental work has shown that mixtures of hard, frictional and\nsoft, nearly frictionless particles exhibit wider shear zones than samples with\nonly one of the two components. To explain this finding, we investigate the\nshear zone properties and the stress response of granular mixtures using\ndiscrete element simulations. We show that both interparticle friction and\nelastic modulus determine the shear-band properties of granular mixtures of\nvarious mixing ratios, but their stress response depends strongly on the\ninterparticle friction. Our study provides a fundamental understanding of the\nmicromechanics of shear band formation in granular mixtures."
    },
    {
        "anchor": "Microparticle Brownian Motion near an Air-Water Interface Governed by\n  Direction-Dependent Boundary Conditions: Although the dynamics of colloids in the vicinity of a solid interface has\nbeen widely characterized in the past, experimental studies of Brownian\ndiffusion close to an air-water interface are rare and limited to\nparticle-interface gap distances larger than the particle size. At the still\nunexplored lower distances, the dynamics is expected to be extremely sensitive\nto boundary conditions at the air-water interface. There, ad hoc experiments\nwould provide a quantitative validation of predictions. Using a specially\ndesigned dual wave interferometric setup, the 3D dynamics of 9 micrometers\ndiameter particles at a few hundreds of nanometers from an air-water interface\nis here measured in thermal equilibrium. Intriguingly, while the measured\ndynamics parallel to the interface approaches expected predictions for slip\nboundary conditions, the Brownian motion normal to the interface is very close\nto the predictions for no-slip boundary conditions. These puzzling results are\nrationalized considering current models of incompressible interfacial flow and\ndeepened developing an ad hoc model which considers the contribution of tiny\nconcentrations of surface active particles at the interface. We argue that such\ncondition governs the particle dynamics in a large spectrum of systems ranging\nfrom biofilm formation to flotation process.",
        "positive": "Ice Rule and Emergent Frustration in Particle Ice and Beyond: Geometric frustration and the ice rule are two concepts that are intimately\nconnected and widespread across condensed matter. The first refers to the\ninability of a system to satisfy competing interactions in the presence of\nspatial constraints. The second, in its more general sense, represents a\nprescription for the minimization of the topological charges in a constrained\nsystem. Both can lead to manifolds of high susceptibility and non-trivial,\nconstrained disorder where exotic behaviors can appear and even be designed\ndeliberately. In this Colloquium, we describe the emergence of geometric\nfrustration and the ice rule in soft condensed matter. This Review excludes the\nextensive developments of mathematical physics within the field of geometric\nfrustration, but rather focuses on systems of confined micro- or mesoscopic\nparticles that emerge as a novel paradigm exhibiting spin degrees of freedom.\nIn such systems, geometric frustration can be engineered artificially by\ncontrolling the spatial topology and geometry of the lattice, the position of\nthe individual particle units, or their relative filling fraction. These\ncapabilities enable the creation of novel and exotic phases of matter, and also\npotentially lead towards technological applications related to memory and logic\ndevices that are based on the motion of topological defects. We review the\nrapid progress in theory and experiments and discuss the intimate physical\nconnections with other frustrated systems at different length scales."
    },
    {
        "anchor": "A New Phenomenon: Sub-Tg, Solid-State, Plasticity-Induced Bonding in\n  Polymers: Polymer self-adhesion due to the interdiffusion of macromolecules has been an\nactive area of research for several decades [70, 43, 62, 42, 72, 73, 41]. Here,\nwe report a new phenomenon of sub-Tg, solid-state, plasticity-induced bonding;\nwhere amorphous polymeric films were bonded together in a period of time on the\norder of a second in the solid-state at ambient temperatures nearly 60 K below\ntheir glass transition temperature (Tg) by subjecting them to active plastic\ndeformation. Despite the glassy regime, the bulk plastic deformation triggered\nthe requisite molecular mobility of the polymer chains, causing\ninterpenetration across the interfaces held in contact. Quantitative levels of\nadhesion and the morphologies of the fractured interfaces validated the sub-Tg,\nplasticity-induced, molecular mobilization causing bonding. No-bonding outcomes\n(i) during the compression of films in a near hydrostatic setting (which\ninhibited plastic flow) and (ii) between an 'elastic' and a 'plastic' film\nfurther established the explicit role of plastic deformation in this newly\nreported sub-Tg solid-state bonding .",
        "positive": "Stratification of mixtures in evaporating liquid films occurs only for a\n  range of volume fractions of the smaller component: I model the drying of a liquid film containing small and big colloid\nparticles. Fortini et al. [A. Fortini et al, Phys. Rev. Lett. 116, 118301\n(2016)] studied these films with both computer simulation and experiment. They\nfound that at the end of drying the mixture had stratified with a layer of the\nsmaller particles on top of the big particles. I develop a simple model for\nthis process. The model has two ingredients: arrest of the diffusion of the\nparticles at high density, and diffusiophoretic motion of the big particles due\nto gradients in the concentration of the small particles. The model predicts\nthat stratification only occurs over a range of initial concentrations of the\nsmaller colloidal species. At concentrations that are either too low or too\nhigh, the concentration gradients due to drying are not enough to push the big\nparticles away and so produce a layer at the top of only small particles. In\nagreement with earlier work, the model also predicts that large Peclet numbers\nfor drying are needed to see stratification."
    },
    {
        "anchor": "Diffusion and Relaxation Dynamics in Cluster Crystals: For a large class of fluids exhibiting ultrasoft bounded pair potentials,\nparticles form crystals consisting of clusters located in the lattice sites,\nwith a density-independent lattice constant. Here we present an investigation\non the dynamic features of a representative example of this class. It is found\nthat particles can diffuse between lattice sites, maintaining the lattice\nstructure, through an activated hopping mechanism. This feature yields finite\nvalues for the diffusivity and full relaxation of density correlation\nfunctions. Simulations suggest the existence of a localization transition which\nis avoided by hopping, and a dynamic decoupling between self- and collective\ncorrelations.",
        "positive": "Transmission and Conversion of Energy by Coupled Soft Gears: Dynamical aspects of coupled deformable gears are investigated to clarify the\ndifferences of mechanical properties between the machines consist of hard\nmaterials and those of soft materials. In particular, the performances of two\nfunctions, the transmission and the conversion of the energy, are compared\nbetween the hard and soft gears systems. First, the responses of the coupled\ngears against a constant torque working on one of gears are focused for two\ntypes of couplings; P) a pair gears are coupled, and T) three gears are coupled\nwith forming a regular triangle. In systems with the coupling P), we obtain\ntrivial results that the rotational energy can be transmitted to other gear\nonly if these gears are hard enough. On the other hand, in systems with the\ncoupling T), the transmission of the rotational energy to one of the other\ngears appears only if these gears are soft enough. Second, we show the\nresponses of this system in which one of gears have contact with a high\ntemperature heat bath and the other gears have contact with a 0 temperature\nheat bath. With the coupling T), the directional rotations appear in two gears\nhaving contact with 0 temperature heat bath. Here, the direction of these\nrotations change depending on the noise strength."
    },
    {
        "anchor": "Three-dimensional lattice-Boltzmann simulations of critical spinodal\n  decomposition in binary immiscible fluids: We use a modified Shan-Chen, noiseless lattice-BGK model for binary\nimmiscible, incompressible, athermal fluids in three dimensions to simulate the\ncoarsening of domains following a deep quench below the spinodal point from a\nsymmetric and homogeneous mixture into a two-phase configuration. We find the\naverage domain size growing with time as $t^\\gamma$, where $\\gamma$ increases\nin the range $0.545 < \\gamma < 0.717$, consistent with a crossover between\ndiffusive $t^{1/3}$ and hydrodynamic viscous, $t^{1.0}$, behaviour. We find\ngood collapse onto a single scaling function, yet the domain growth exponents\ndiffer from others' works' for similar values of the unique characteristic\nlength and time that can be constructed out of the fluid's parameters. This\nrebuts claims of universality for the dynamical scaling hypothesis. At early\ntimes, we also find a crossover from $q^2$ to $q^4$ in the scaled structure\nfunction, which disappears when the dynamical scaling reasonably improves at\nlater times. This excludes noise as the cause for a $q^2$ behaviour, as\nproposed by others. We also observe exponential temporal growth of the\nstructure function during the initial stages of the dynamics and for\nwavenumbers less than a threshold value.",
        "positive": "Sudden collapse of a colloidal gel: Metastable gels formed by weakly attractive colloidal particles display a\ndistinctive two-stage time-dependent settling behavior under their own weight.\nInitially a space-spanning network is formed that for a characteristic time,\nwhich we define as the lag time $\\taud$, resists compaction. This solid-like\nbehavior persists only for a limited time. Gels whose age $\\tw$ is greater than\n$\\taud$ yield and suddenly collapse. We use a combination of confocal\nmicroscopy, rheology and time-lapse video imaging to investigate both the\nprocess of sudden collapse and its microscopic origin in an refractive-index\nmatched emulsion-polymer system. We show that the height $h$ of the gel in the\nearly stages of collapse is well described by the surprisingly simple\nexpression, $h(\\ts) = \\h0 - A \\ts^{3/2}$, with $\\h0$ the initial height and\n$\\ts = \\tw-\\taud$ the time counted from the instant where the gel first yields.\nWe propose that this unexpected result arises because the colloidal network\nprogressively builds up internal stress as a consequence of localized\nrearrangement events which leads ultimately to collapse as thermal equilibrium\nis re-established."
    },
    {
        "anchor": "Chain connectivity and conformational variability of polymers: Clues to\n  an adequate thermodynamic description of their solutions I: Dilute solutions: This is the first of two parts investigating the Flory-Huggins interaction\nparameter chi as a function of composition and chain length. Part I encompasses\nexperimental and theoretical work. The former comprises the synthesis of\npoly(dimethylsiloxane)s with different molar mass and the measurements of their\nsecond osmotic virial coefficients in solvents of diverse quality as a function\nof M via light scattering and osmotic pressures. The theoretical analysis is\nperformed by subdividing the dilution process into two clearly separable\nstates. It yields a simple expression for the range of pair interaction\ncontaining three parameters. The parameter alpha measures the effect of contact\nformation between solvent molecules and polymer segments at fixed chain\nconformation, whereas the parameter zeta quantifies the contributions of the\nconformational changes taking place in response to dilution; zeta becomes zero\nfor theta conditions. &#61472;The influences of M are exclusively contained in\nthe parameter lambda&#61486;&#61472; The new relation is capable of describing\nhitherto incomprehensible experimental findings, like a diminution of chi with\nrising M. The evaluation of experimental information for different systems\naccording to the established equation displays the existence of a linear\ninterrelation between zeta and alpha. Part II of this investigation generalizes\nthe present approach to solutions of arbitrary composition and discusses the\nphysical meaning of the parameters in more detail.",
        "positive": "Scaling behavior in the convection-driven Brazil-nut effect: The Brazil-nut effect is the phenomenon in which a large intruder particle\nimmersed in a vertically shaken bed of smaller particles rises to the top, even\nwhen it is much denser. The usual practice, while describing these experiments,\nhas been to use the dimensionless acceleration \\Gamma=a \\omega^2/g, where a and\n\\omega are respectively the amplitude and the angular frequency of vibration\nand g is the acceleration due to gravity. Considering a vibrated\nquasi-two-dimensional bed of mustard seeds, we show here that the peak-to-peak\nvelocity of shaking v= a\\omega, rather than \\Gamma, is the relevant parameter\nin the regime where boundary-driven granular convection is the main driving\nmechanism. We find that the rise-time \\tau of an intruder is described by the\nscaling law \\tau ~ (v-v_c)^{-\\alpha}, where v_c is identified as the critical\nvibration velocity for the onset of convective motion of the mustard seeds.\nThis scaling form holds over a wide range of (a,\\omega), diameter and density\nof the intruder."
    },
    {
        "anchor": "A Triangular Tessellation Scheme for the Adsorption Free Energy at the\n  Liquid-Liquid Interface: Towards Non-Convex Patterned Colloids: We introduce a new numerical technique, namely triangular tessellation, to\ncalculate the free energy associated with the adsorption of a colloidal\nparticle at a flat interface. The theory and numerical scheme presented here\nare sufficiently general to handle non-convex patchy colloids with arbitrary\nsurface patterns characterized by a wetting angle, e.g., amphiphilicity. We\nignore interfacial deformation due to capillary, electrostatic, or\ngravitational forces, but the method can be extended to take such effects into\naccount. It is verified that the numerical method presented is accurate and\nsufficiently stable to be applied to more general situations than presented in\nthis paper. The merits of the tessellation method prove to outweigh those of\ntraditionally used semi-analytic approaches, especially when it comes to\ngenerality and applicability.",
        "positive": "Phase Behavior of a Simple Model for Membrane Proteins: We report a numerical simulation of the phase diagram of a simple model for\nmembrane proteins constrained to move in a plane. In analogy with the\ncorresponding three dimensional models, the liquid-gas transition becomes\nmetastable as the range of attraction decreases. Spontaneous crystallization\nhappens much more readily in the two dimensional models rather than in their\nthree dimensional counterparts."
    },
    {
        "anchor": "In silico study of liquid crystalline phases formed by bent-shaped\n  molecules with excluded-volume type interactions: We have numerically studied a liquid composed of achiral, bent-shaped\nmolecules built of tangent spheres. The system is known to spontaneously break\nmirror symmetry, as it forms a macroscopically chiral, twist-bend nematic phase\n[Phys. Rev. Lett. 115, 147801 (2015)]. Here, we have examined the full phase\ndiagram of such liquid and observed several phases characterized by\norientational and/or translational ordering of molecules. Apart from\nconventional nematic, smectic A, and the above-mentioned twist-bend nematic\nphase, we have identified antiferroelectric smectic A phase. For large\ndensities and a high degree of molecule's structural bend, another smectic\nphase emerged, where the polarization vector rotates within a single smectic\nlayer. These results were confirmed using both Monte Carlo and molecular\ndynamics simulations.",
        "positive": "The motion, stability and breakup of a stretching liquid bridge with a\n  receding contact line: The complex behavior of drop deposition on a hydrophobic surface is\nconsidered by looking at a model problem in which the evolution of a\nconstant-volume liquid bridge is studied as the bridge is stretched. The bridge\nis pinned with a fixed diameter at the upper contact point, but the contact\nline at the lower attachment point is free to move on a smooth substrate.\nExperiments indicate that initially, as the bridge is stretched, the lower\ncontact line slowly retreats inwards. However at a critical radius, the bridge\nbecomes unstable, and the contact line accelerates dramatically, moving inwards\nvery quickly. The bridge subsequently pinches off, and a small droplet is left\non the substrate. A quasi-static analysis, using the Young-Laplace equation, is\nused to accurately predict the shape of the bridge during the initial bridge\nevolution, including the initial onset of the slow contact line retraction. A\nstability analysis is used to predict the onset of pinch-off, and a\none-dimensional dynamical equation, coupled with a Tanner-law for the dynamic\ncontact angle, is used to model the rapid pinch-off behavior. Excellent\nagreement between numerical predictions and experiments is found throughout the\nbridge evolution, and the importance of the dynamic contact line model is\ndemonstrated."
    },
    {
        "anchor": "From Liquid Structure to Configurational Entropy: Introducing Structural\n  Covariance: We connect the configurational entropy of a liquid to the geometrical\nproperties of its local energy landscape, using a high-temperature expansion.\nIt is proposed that correlations between local structures arises from their\noverlap and, being geometrical in nature, can be usefully determined using the\ninherent structures of high temperature liquids. We show quantitatively how the\nhigh-temperature covariance of these local structural fluctuations arising from\ntheir geometrical overlap, combined with their energetic stability, control the\ndecrease of entropy with decreasing energy. We apply this formalism to a family\nof Favoured Local Structure (FLS) lattice models with two low symmetry FLS's\nwhich are found to either crystallize or form a glass on cooling. The\ncovariance, crystal energy and estimated freezing temperature are tested as\npossible predictors of glass-forming ability in the model system.",
        "positive": "Non-equilibrium raft-like membrane domains under continuous recycling: We present a model for the kinetics of spontaneous membrane domain (raft)\nassembly that includes the effect of membrane recycling ubiquitous in living\ncells. We show that the domains have a broad power-law distribution with an\naverage radius that scales with the 1/4 power of the domain lifetime when the\nline tension at the domain edges is large. For biologically reasonable\nrecycling and diffusion rates the average domain radius is in the tens of nm\nrange, consistent with observations. This represents one possible link between\nsignaling (involving rafts) and traffic (recycling) in cells. Finally, we\npresent evidence that suggests that the average raft size may be the same for\nall scale-free recycling schemes."
    },
    {
        "anchor": "Spanning the Scales of Granular Materials: Microscopic Force Imaging: If you walk on sand, it supports your weight. How do the disordered forces\nbetween particles in sand organize, to keep you from sinking? This simple\nquestion is surprisingly difficult to answer experimentally: measuring forces\nin three dimensions, between deeply buried grains, is challenging. We describe\nhere experiments in which we have succeeded in measuring forces inside a\ngranular packing subject to controlled deformations. We connect the measured\nmicro-scale forces to the macro-scale packing force response with an averaging,\nmean field calculation. This calculation explains how the combination of\npacking structure and contact deformations produce the unexpected mechanical\nresponse of the packing, and reveals a surprising microscopic particle\ndeformation enhancement mechanism.",
        "positive": "Isotropic-nematic transition in a mixture of hard spheres and hard\n  spherocylinders: scaled particle theory description: The scaled particle theory is developed for the description of\nthermodynamical properties of a mixture of hard spheres and hard\nspherocylinders. Analytical expressions for free energy, pressure and chemical\npotentials are derived. From the minimization of free energy, a nonlinear\nintegral equation for the orientational singlet distribution function is\nformulated. An isotropic-nematic phase transition in this mixture is\ninvestigated from the bifurcation analysis of this equation. It is shown that\nwith an increase of concentration of hard spheres, the total packing fraction\nof a mixture on phase boundaries slightly increases. The obtained results are\ncompared with computer simulations data."
    },
    {
        "anchor": "Generation and interaction of solitons in Bose-Einstein condensates: Generation, interaction and detection of dark solitons in Bose-Einstein\ncondensates is considered. In particular, we focus on the dynamics resulting\nfrom phase imprinting and density engineering. The generation of soliton pairs\nas well as their interaction is also considered. Finally, motivated by the\nrecent experimental results of Cornish et al. (Phys. Rev Lett. 85, 1795, 2000),\nwe analyze the stability of dark solitons under changes of the scattering\nlength and thereby demonstrate a new way to detect them. Our theoretical and\nnumerical results compare well with the existing experimental ones and provide\nguidance for future experiments.",
        "positive": "Deposition of quantum dots in a capillary tube: The ability to assemble nanomaterials, such as quantum dots, enables the\ncreation of functional devices that present unique optical and electronic\nproperties. For instance, light-emitting diodes with exceptional color purity\ncan be printed via the evaporative-driven assembly of quantum dots.\nNevertheless, current studies of the colloidal deposition of quantum dots have\nbeen limited to the surfaces of a planar substrate. Here, we investigate the\nevaporation-driven assembly of quantum dots inside a confined cylindrical\ngeometry. Specifically, we observe distinct deposition patterns, such as\nbanding structures along the length of a capillary tube. Such coating behavior\ncan be influenced by the evaporation speed as well as the concentration of\nquantum dots. Understanding the factors governing the coating process can\nprovide a means to control the assembly of quantum dots inside a capillary\ntube, ultimately enabling the creation of novel photonic devices."
    },
    {
        "anchor": "Thermodynamic anomalies in a lattice model of water: We investigate a lattice-fluid model of water, defined on a three-dimensional\nbody centered cubic lattice. Model molecules possess a tetrahedral symmetry,\nwith four equivalent bonding arms, aiming to mimic the formation of hydrogen\nbonds. The model is similar to the one proposed by Roberts and Debenedetti [J.\nChem. Phys. 105, 658 (1996)], simplified in that no distinction between bond\n\"donors\" and \"acceptors\" is imposed. Bond formation depends both on orientation\nand local density. In the ground state, we show that two different ordered\n(ice) phases are allowed. At finite temperature, we analyze homogeneous phases\nonly, working out phase diagram, response functions, the temperature of maximum\ndensity locus, and the Kauzmann line. We make use of a generalized first order\napproximation on a tetrahedral cluster. In the liquid phase, the model exhibits\nseveral anomalous properties observed in real water. In the low temperature\nregion (supercooled liquid), there are evidences of a second critical point\nand, for some range of parameter values, this scenario is compatible with the\nexistence of a reentrant spinodal.",
        "positive": "Factors Controlling the Pinning Force of Liquid Droplets on Liquid\n  Infused Surfaces: Liquid infused surfaces with partially wetting lubricants have recently been\nexploited for numerous intriguing applications, such as for droplet\nmanipulation, droplet collection and spontaneous motion. When partially wetting\nlubricants are used, the pinning force is a key factor that can strongly affect\ndroplet mobility. Here, we derive an analytical prediction for contact angle\nhysteresis {in the limit where the meniscus size is much smaller than the\ndroplet}, and numerically study how it is controlled by the solid fraction, the\nlubricant wetting angles, and the various fluid surface tensions. We further\nrelate the contact angle hysteresis and the pinning force experienced by a\ndroplet on a liquid infused surface, and our predictions for the critical\nsliding angles are consistent with existing experimental observations. Finally,\nwe discuss why a droplet on a liquid infused surface with partially wetting\nlubricants typically experiences stronger pinning compared to a droplet on a\nclassical superhydrophobic surface."
    },
    {
        "anchor": "Mechanical response to tension and torque of molecular chains via\n  statistically interacting particles associated with extension, contraction,\n  twist, and supercoiling: A methodology for the statistical mechanical analysis of polymeric chains\nunder tension introduced previously is extended to include torque. The response\nof individual bonds between monomers or of entire groups of monomers to a\ncombination of tension and torque involves, in the framework of this method of\nanalysis, the (thermal or mechanical) activation of a specific mix of\nstatistically interacting particles carrying quanta of extension or contraction\nand quanta of twist or supercoiling. The methodology, which is elucidated in\napplications of increasing complexity, is capable of describing the conversion\nbetween twist chirality and plectonemic chirality in quasistatic processes. The\ncontrol variables are force or extension and torque or linkage (a combination\nof twist and writhe). The versatility of this approach is demonstrated in two\napplications relevant and promising for double-stranded DNA under controlled\ntension and torque. One application describes conformational transformations\nbetween (native) B-DNA, (underwound) S-DNA, and (overwound) P-DNA in accord\nwith experimental data. The other application describes how the conversion\nbetween a twisted chain and a supercoiled chain accommodates variations of\nlinkage and excess length in a buckling transition.",
        "positive": "Controlling the micellar morphology of binary PEO-PCL block copolymers\n  in water-THF through controlled blending: We study both experimentally and theoretically the self-assembly of binary\nblock copolymers in dilute solution, where self-assembly is triggered by\nchanging the solvent from the common good solvent THF to the selective solvent\nwater, and where the two species on their own in water form vesicles and\nspherical micelles respectively. We find that in water the inter-micellar\nexchange of these block copolymers is very slow so that the self-assembled\nstructures are in local but not global equilibrium (i.e., they are\nnon-ergodic). This opens up the possibility of controlling micelle morphology\nboth thermodynamically and kinetically. Specifically, when the two species are\nfirst dissolved in THF before mixing and self-assembly (`premixing') by\ndilution with water, the morphology is found to depend on the mixing ratio of\nthe two species, going gradually from vesicles via `bulbed' rods, rings,\nY-junctions and finally to spherical micelles as we increase the proportion of\nthe sphere-formers. On the other hand, if the two species are first partially\nself-assembled (by partial exchange of the solvent with water) before mixing\nand further self-assembly (`intermediate mixing'), novel metastable structures,\nincluding nanoscopic pouches, emerge. These experimental results are\ncorroborated by self-consistent field theory calculations (SCFT) which\nreproduce the sequence of morphologies seen in the pre-mixing experiments. SCFT\nalso reveals a clear coupling between polymer composition and aggregate\ncurvature, with regions of positive and negative curvature being stabilized by\nan enrichment and depletion of sphere formers respectively. Our study\ndemonstrates that both thermodynamic and kinetic blending of block copolymers\nare effective design parameters to control the resulting structures and allow\nus to access a much richer range of nano-morphologies than is possible with\nmonomodal block copolymer solutions."
    },
    {
        "anchor": "Swarming of Self-Propelled Camphor Boats: When an ensemble of self-propelled camphor boats move in a one-dimensional\nchannel, they exhibit a variety of collective behaviors. Under certain\nconditions, the boats tend to cluster together and move in a relatively tight\nformation. This type of behavior, referred to as clustering or swarming here,\nis one of three types recently observed in experiment. Similar clustering\nbehavior is also reproduced in simulations based on a simple theoretical model.\nHere we examine this model to determine the clustering mechanism and the\nconditions under which clustering occurs. We also propose a method of\nquantifying the behavior that may be used in future experimental work.",
        "positive": "Phase ordering of two-dimensional symmetric binary fluids: a droplet\n  scaling state: The late-stage phase ordering, in $d=2$ dimensions, of symmetric fluid\nmixtures violates dynamical scaling. We show however that, even at 50/50 volume\nfractions, if an asymmetric droplet morphology is initially present then this\nsustains itself, throughout the viscous hydrodynamic regime, by a\n`coalescence-induced coalescence' mechanism. Scaling is recovered (with length\nscale $l \\sim t$, as in $d=3$). The crossover to the inertial hydrodynamic\nregime is delayed even longer than in $d=3$; on entering it, full symmetry is\nfinally restored and we find $l\\sim t^{2/3}$, regardless of the initial state."
    },
    {
        "anchor": "Structural anomalies for a three dimensional isotropic core-softened\n  potential: Using molecular dynamics simulations we investigate the structure of a system\nof particles interacting through a continuous core-softened interparticle\npotential. We found for the translational order parameter, t, a local maximum\nat a density $\\rho_{t-max}$ and a local minimum at $\\rho_{t-min} >\n\\rho_{t-max}$. Between $\\rho_{t-max}$ and $\\rho_{t-min}$, the $t$ parameter\nanomalously decreases upon pressure. For the orientational order parameter,\n$Q_6$, was observed a maximum at a density $\\rho_{t-max}< \\rho_{Qmax} <\n\\rho_{t-min}$. For densities between $\\rho_{Qmax}$ and $\\rho_{t-min}$, both the\ntranslational (t) and orientational ($Q_6$) order parameters have anomalous\nbehavior. We know that this system also exhibits density and diffusion anomaly.\nWe found that the region in the pressure-temperature phase-diagram of the\nstructural anomaly englobes the region of the diffusion anomaly that is larger\nthan the region limited by the temperature of maximum density. This cascade of\nanomalies (structural, dynamic and thermodynamic) for our model has the same\nhierarchy of that one observed for the SPC/E water.",
        "positive": "Microscopic Characterization of Individual Submicron Bubbles during the\n  Layer-by-Layer Deposition: Towards Creating Smart Agents: We investigated the individual properties of various polyion-coated bubbles\nwith a mean diameter ranging from 300 to 500 nm. Dark field microscopy allows\none to track the individual particles of the submicron bubbles (SBs)\nencapsulated by the layer-by-layer (LbL) deposition of cationic and anionic\npolyelectrolytes (PEs). Our focus is on the two-step charge reversals of PE-SB\ncomplexes: the first is a reversal from negatively charged bare SBs with no PEs\nadded to positive SBs encapsulated by polycations (monolayer deposition), and\nthe second is overcharging into negatively charged PE-SB complexes due to the\nsubsequent addition of polyanions (double-layer deposition). The details of\nthese phenomena have been clarified through the analysis of a number of\ntrajectories of various PE-SB complexes that experience either Brownian motion\nor electrophoresis. The contrasted results obtained from the analysis were as\nfollows: an amount in excess of the stoichiometric ratio of the cationic\npolymers was required for the first charge-reversal, whereas the stoichiometric\naddition of the polyanions lead to the electrical neutralization of the PE-SB\ncomplex particles. The recovery of the stoichiometry in the double-layer\ndeposition paves the way for fabricating multi-layered SBs encapsulated solely\nwith anionic and cationic PEs, which provides a simple protocol to create smart\nagents for either drug delivery or ultrasound contrast imaging."
    },
    {
        "anchor": "Poiseuille flow of soft polycrystals in 2D rough channels: Polycrystals are partially ordered solids where crystalline order extends\nover mesoscopic length scales, namely, the grain size. We study the Poisuielle\nflow of such materials in a rough channel. In general, similar to yield stress\nfluids, three distinct dynamical states, namely, flowing, stick-slip and jammed\ncan be observed, with a yield threshold dependent on channel width.\nImportantly, the interplay between the finite channel width, and the intrinsic\nordering scale (the grain size) leads to new type of spatiotemporal\nheterogeneity. In wide channels, although the average flow profile remains plug\nlike, at the underlying granular level, there is vigorous grain remodelling\nactivity resulting from the velocity heterogeneity among the grains. As the\nchannel width approaches typical grain size, the flowing polycrystalline state\nbreaks up into a spatially heterogeneous mixture of flowing liquid like patches\nand chunks of nearly static grains. Despite these static grains, the average\nvelocity still shows a parabolic profile, dominated by the moving liquid like\npatches. However, the solid-liquid front moves at nearly constant speed in the\nopposite direction of the external drive.",
        "positive": "A circle swimmer at low Reynolds number: Swimming in circles occurs in a variety of situations at low Reynolds number.\nHere we propose a simple model for a swimmer that undergoes circular motion,\ngeneralising the model of a linear swimmer proposed by Najafi and Golestanian\n(Phys. Rev. E 69, 062901 (2004)). Our model consists of three solid spheres\narranged in a triangular configuration, joined by two links of time-dependent\nlength. For small strokes, we discuss the motion of the swimmer as a function\nof the separation angle between its links. We find that swimmers describe\neither clockwise or anticlockwise circular motion depending on the tilting\nangle in a non-trivial manner. The symmetry of the swimmer leads to a\nquadrupolar decay of the far flow field. We discuss the potential extensions\nand experimental realisation of our model."
    },
    {
        "anchor": "Density Scaling and Dynamic Correlations in Viscous Liquids: We use a recently proposed method [Berthier L.; Biroli G.; Bouchaud J.P.;\nCipelletti L.; El Masri D.; L'Hote D.; Ladieu F.; Pierno M. Science 2005, 310,\n1797.] to obtain an approximation to the 4-point dynamic correlation function\nfrom derivatives of the linear dielectric response function. For four liquids\nover a range of pressures, we find that the number of dynamically correlated\nmolecules, Nc, depends only on the magnitude of the relaxation time,\nindependently of temperature and pressure. This result is consistent with the\ninvariance of the shape of the relaxation dispersion at constant relaxation\ntime and the density scaling property of the relaxation times, and implies that\nNc also conforms to the same scaling behavior. For propylene carbonate and\nsalol Nc becomes constant with approach to the Arrhenius regime, consistent\nwith the value of unity expected for intermolecularly non-cooperative\nrelaxation.",
        "positive": "Bridges in three-dimensional granular packings: experiments and\n  simulations: In this letter, we present the first experimental study of bridge structures\nin three-dimensional dry granular packings. When bridges are small, they are\npredominantly 'linear', and have an exponential size distribution. Larger,\npredominantly 'complex' bridges, are confirmed to follow a power-law size\ndistribution. Our experiments, which use X-ray tomography, are in good\nagreement with the simulations presented here, for the distribution of sizes,\nend-to-end lengths, base extensions and orientations of predominantly linear\nbridges. Quantitative differences between the present experiment and earlier\nsimulations suggest that packing fraction is an important determinant of bridge\nstructure."
    },
    {
        "anchor": "Temperature-Controlled Slip of Polymer Melts on Ideal Substrates: The temperature dependence of the hydrodynamic boundary condition between a\nPDMS melt and two different non-attractive surfaces made of either an OTS\n(octadecyltrichlorosilane) self-assembled monolayer (SAM) or a grafted layer of\nshort PDMS chains has been characterized. A slip length proportional to the\nfluid viscosity is observed on both surfaces. The slip temperature dependence\nis deeply influenced by the surfaces. The viscous stress exerted by the polymer\nliquid on the surface is observed to follow exactly the same temperature\ndependences as the friction stress of a cross-linked elastomer sliding on the\nsame surfaces. Far above the glass transition temperature, these observations\nare rationalized in the framework of a molecular model based on activation\nenergies: increase or decrease of the slip length with increasing temperatures\ncan be observed depending on how the activation energy of the bulk viscosity\ncompares to that of the interfacial Navier's friction coefficient.",
        "positive": "Rate dependent shear bands in a shear transformation zone model of\n  amorphous solids: We use Shear Transformation Zone (STZ) theory to develop a deformation map\nfor amorphous solids as a function of the imposed shear rate and initial\nmaterial preparation. The STZ formulation incorporates recent simulation\nresults [Haxton and Liu, PRL 99 195701 (2007)] showing that the steady state\neffective temperature is rate dependent. The resulting model predicts a wide\nrange of deformation behavior as a function of the initial conditions,\nincluding homogeneous deformation, broad shear bands, extremely thin shear\nbands, and the onset of material failure. In particular, the STZ model predicts\nhomogeneous deformation for shorter quench times and lower strain rates, and\ninhomogeneous deformation for longer quench times and higher strain rates. The\nlocation of the transition between homogeneous and inhomogeneous flow on the\ndeformation map is determined in part by the steady state effective\ntemperature, which is likely material dependent. This model also suggests that\nmaterial failure occurs due to a runaway feedback between shear heating and the\nlocal disorder, and provides an explanation for the thickness of shear bands\nnear the onset of material failure. We find that this model, which resolves\ndynamics within a sheared material interface, predicts that the stress weakens\nwith strain much more rapidly than a similar model which uses a single state\nvariable to specify internal dynamics on the interface."
    },
    {
        "anchor": "Nonlinear response theory for Markov processes II: Fifth-order response\n  functions: The nonlinear response of stochastic models obeying a master equation is\ncalculated up to fifth-order in the external field thus extending the\nthird-order results obtained earlier (G. Diezemann, Phys. Rev. E{\\bf 85},\n051502 (2012)). For sinusoidal fields the $5\\om$-component of the\nsusceptibility is computed for the model of dipole reorientations in an\nasymmetric double well potential and for a trap model with a Gaussian density\nof states. For most realizations of the models a hump is found in the\nhigher-order susceptibilities. In particular, for the asymmetric double well\npotential model there are two characteristic temperature regimes showing the\noccurence of such a hump as compared to a single characteristic regime in case\nof the third-order response. In case of the trap model the results strongly\ndepend on the variable coupled to the field. As for the third-order response,\nthe low-frequency limit of the susceptibility plays a crucial role with respect\nto the occurence of a hump. The findings are discussed in light of recent\nexperimental results obtained for supercooled liquids. The differences found\nfor the third-order and the fifth-order response indicate that nonlinear\nresponse functions might serve as a powerful tool to discriminate among the\nlarge number of existing models for glassy relaxation.",
        "positive": "Geometric partition functions of cellular systems: Explicit calculation\n  of the entropy in two and three dimensions: A method is proposed for the characterisation of the entropy of cellular\nstructures, based on the compactivity concept for granular packings.\nHamiltonian-like volume functions are constructed both in two and in three\ndimensions, enabling the identification of a phase space and making it possible\nto take account of geometrical correlations systematically. Case studies are\npresented for which explicit calculations of the mean vertex density and\nporosity fluctuations are given as functions of compactivity. The formalism\napplies equally well to two- and three-dimensional granular assemblies."
    },
    {
        "anchor": "Workflow for investigating thermodynamic, structural and energy\n  properties of condensed polymer systems from Molecular Dynamics: Soft matter materials and polymers are widely used in the controlled delivery\nof drugs. Simulation and modeling provide insight at the atomic scale enabling\na level of control unavailable to experiments. We present a workflow protocol\nfor modeling, simulating, and analyzing structural and thermodynamic response\nproperties of poly-lactic-co-glycolic acid (PLGA), a well-studied and FDA\napproved material. We concatenate a battery of molecular dynamics,\ncomputational chemistry, highly parallel scripting, and analysis tools for\ngenerating properties of bulk polymers in the condensed phase. We provide the\nworkflow leading to the glass transition temperature, enthalpy, density,\nisobaric heat capacity, thermal expansion coefficient, isothermal\ncompressibility, bulk modulus, sonic velocity, cohesive energy, and solubility\nparameters. Calculated properties agree very well with experiments, when\navailable. This methodology has been extended to a variety of polymer types and\nenvironments.",
        "positive": "Machine Learning Without a Processor: Emergent Learning in a Nonlinear\n  Electronic Metamaterial: Standard deep learning algorithms require differentiating large nonlinear\nnetworks, a process that is slow and power-hungry. Electronic learning\nmetamaterials offer potentially fast, efficient, and fault-tolerant hardware\nfor analog machine learning, but existing implementations are linear, severely\nlimiting their capabilities. These systems differ significantly from artificial\nneural networks as well as the brain, so the feasibility and utility of\nincorporating nonlinear elements have not been explored. Here we introduce a\nnonlinear learning metamaterial -- an analog electronic network made of\nself-adjusting nonlinear resistive elements based on transistors. We\ndemonstrate that the system learns tasks unachievable in linear systems,\nincluding XOR and nonlinear regression, without a computer. We find our\nnonlinear learning metamaterial reduces modes of training error in order (mean,\nslope, curvature), similar to spectral bias in artificial neural networks. The\ncircuitry is robust to damage, retrainable in seconds, and performs learned\ntasks in microseconds while dissipating only picojoules of energy across each\ntransistor. This suggests enormous potential for fast, low-power computing in\nedge systems like sensors, robotic controllers, and medical devices, as well as\nmanufacturability at scale for performing and studying emergent learning."
    },
    {
        "anchor": "Lattice statistical models for the nematic transitions in\n  liquid-crystalline systems: We investigate the connections between some simple Maier-Saupe lattice\nmodels, with a discrete choice of orientations of the microscopic directors,\nand a recent proposal of a two-tensor formalism to describe the phase diagrams\nof nematic liquid-crystalline systems. This two-tensor proposal is used to\nformulate the statistical problem in terms of fully-connected lattice\nHamiltonians, with the local nematic directors restricted to the Cartesian\naxes. Depending on the choice of interaction parameters, we regain all of the\nmain features of the original mean-field two-tensor calculations. With a\nstandard choice of parameters, we obtain the well-known sequence of isotropic,\nuniaxial, and biaxial nematic structures, with a Landau multicritical point.\nWith another suitably chosen set of parameters, we obtain two tricritical\npoints, according to some recent predictions of the two-tensor calculations.\nThe simple statistical lattice models are quite easy to work with, for all\nvalues of parameters, and the present calculations can be carried out beyond\nthe mean-field level.",
        "positive": "Integer topological defects of cell monolayers -- mechanics and flows: Monolayers of anisotropic cells exhibit long-ranged orientational order and\ntopological defects. During the development of organisms, orientational order\noften influences morphogenetic events. However, the linkage between the\nmechanics of cell monolayers and topological defects remains largely\nunexplored. This holds specifically at the time scales relevant for tissue\nmorphogenesis. Here, we build on the physics of liquid crystals to determine\nmaterial parameters of cell monolayers. In particular, we use a hydrodynamical\ndescription of an active polar fluid to study the steady-state mechanical\npatterns at integer topological defects. Our description includes three\ndistinct sources of activity: traction forces accounting for cell-substrate\ninteractions as well as anisotropic and isotropic active nematic stresses\naccounting for cell-cell interactions. We apply our approach to C2C12 cell\nmonolayers in small circular confinements, which form isolated aster or spiral\ntopological defects. By analyzing the velocity and orientational order fields\nin spirals as well as the forces and cell number density fields in asters, we\ndetermine mechanical parameters of C2C12 cell monolayers. Our work shows how\ntopological defects can be used to fully characterize the mechanical properties\nof biological active matter."
    },
    {
        "anchor": "Dark Field Differential Dynamic Microscopy enables the accurate\n  characterization of the roto-translational dynamics of bacteria and colloidal\n  clusters: Micro- and nanoscale objects with anisotropic shape are key components of a\nvariety of biological systems and inert complex materials, and represent\nfundamental building blocks of novel self-assembly strategies. The time scale\nof their thermal motion is set by their translational and rotational diffusion\ncoefficients, whose measurement may become difficult for relatively large\nparticles with small optical contrast. Here we show that Dark Field\nDifferential Dynamic Microscopy is the ideal tool for probing the\nroto-translational Brownian motion of shape anisotropic particles. We\ndemonstrate our approach by successful application to aqueous dispersions of\nnon-motile bacteria and of colloidal aggregates of spherical particles.",
        "positive": "Marangoni effects on a thin liquid film coating a sphere with axial or\n  radial thermal gradients: We study the time evolution of a thin liquid film coating the outer surface\nof a sphere in the presence of gravity, surface tension and thermal gradients.\nWe derive the fourth-order nonlinear partial differential equation that models\nthe thin film dynamics, including Marangoni terms arising from the dependence\nof surface tension on temperature. We consider two different imposed\ntemperature distributions with axial or radial thermal gradients. We analyze\nthe stability of a uniform coating under small perturbations and carry out\nnumerical simulations in COMSOL for a range of parameter values. In the case of\nan axial temperature gradient, we find steady states with either uniform film\nthickness, or with the fluid accumulating at the bottom or near the top of the\nsphere, depending on the total volume of liquid in the film, dictating whether\ngravity or Marangoni effects dominate. In the case of a radial temperature\ngradient, a stability analysis reveals the most unstable non-axisymmetric modes\non an initially uniform coating film."
    },
    {
        "anchor": "Bending Instability of Rod-shaped Bacteria: A thin-walled tube, e.g., a drinking straw, manifests an instability when\nbent by localizing the curvature change in a small region. This instability has\nbeen extensively studied since the seminal work of Brazier nearly a century\nago. However, the scenario of pressurized tubes has received much less\nattention. Motivated by rod-shaped bacteria such as E. coli, whose cell walls\nare much thinner than their radius and are subject to a substantial internal\npressure, we study, theoretically, how this instability is affected by this\ninternal pressure. In the parameter range relevant to the bacteria, we find\nthat the internal pressure significantly postpones the onset of the\ninstability, while the bending stiffness of the cell wall has almost no\ninfluence. This study suggests a new method to infer turgor pressure in\nrod-shaped bacteria from bending experiments.",
        "positive": "Effects of spatially-varying substrate anchoring on instabilities and\n  dewetting of thin Nematic Liquid Crystal films: Partially wetting nematic liquid crystal (NLC) films on substrates are\nunstable to dewetting-type instabilities due to destablizing solid/NLC\ninteraction forces. These instabilities are modified by the nematic nature of\nthe films, which influences the effective solid/NLC interaction. In this work,\nwe focus on the influence of imposed substrate anchoring on the instability\ndevelopment. The analysis is carried out within a long-wave formulation based\non the Leslie-Ericksen description of NLC films. Linear stability analysis of\nthe resulting equations shows that some features of the instability, such as\nemerging wavelengths, may not be influenced by the imposed substrate anchoring.\nGoing further into the nonlinear regime, considered via large-scale GPU-based\nsimulations, shows however that nonlinear effects may play an important role,\nin particular in the case of strong substrate anchoring anisotropy. Our\nsimulations show that instability of the film develops in two stages: the first\nstage involves formation of ridges that are perpendicular to the local\nanchoring direction; and the second involves breakup of these ridges and\nformation of drops, whose final distribution is influenced by the anisotropy\nimposed by the substrate. Finally, we show that imposing more complex substrate\nanisotropy patterns allows us to reach basic understanding of the influence of\nsubstrate-imposed defects in director orientation on the instability evolution."
    },
    {
        "anchor": "Inwardly curved polymer brushes : Concave is not like Convex: Inwardly curved polymer brushes are present in cylindrical and spherical\nmicelles or in membranes tubes and vesicles decorated with anchored polymers,\nand influence their stability. We consider such polymer brushes in good solvent\nand show that previous works, based on a self-similar concentric structure of\nthe brush, are physically inconsistent. We use scaling laws to derive very\nsimply the leading term of the free energy in the high curvature limit, where\nthe osmotic pressure is the relevant physical ingredient. We also derive the\ncomplete conformation at all curvatures using a self-consistent field approach.\nThe free energy is computed therefrom using a local scaling description.",
        "positive": "Probing helium interfaces with light scattering : from fluid mechanics\n  to statistical physics: We have investigated the formation of helium droplets in two physical\nsituations. In the first one, droplets are atomised from superfluid or normal\nliquid by a fast helium vapour flow. In the second, droplets of normal liquid\nare formed inside porous glasses during the process of helium condensation. The\ncontext, aims, and results of these experiments are reviewed, with focus on the\nspecificity of light scattering by helium. In particular, we discuss how, for\ndifferent reasons, the closeness to unity of the index of refraction of helium\nallows in both cases to minimise the problem of multiple scattering and obtain\nresults which it would not be possible to get using other fluids."
    },
    {
        "anchor": "Defect driven shapes in nematic droplets: analogies with cell division: Building on the striking similarity between the structure of the spindle\nduring mitosis in living cells and nematic textures in confined liquid\ncrystals, we use a continuum model of two-dimensional nematic liquid crystal\ndroplets, to examine the physical aspects of cell division. The model\ninvestigates the interplay between bulk elasticity of the microtubule assembly,\ndescribed as a nematic liquid crystal, and surface elasticity of the cell\ncortex, modelled as a bounding flexible membrane, in controlling cell shape and\ndivision. The centrosomes at the spindle poles correspond to the cores of the\ntopological defects required to accommodate nematic order in a closed geometry.\nWe map out the progression of both healthy bipolar and faulty multi-polar\ndivision as a function of an effective parameter that incorporates active\nprocesses and controls centrosome separation. A robust prediction, independent\nof energetic considerations, is that the transition from a single cell to\ndaughters cells occurs at critical value of this parameter. Our model\nadditionally suggests that microtubule anchoring at the cell cortex may play an\nimportant role for successful bipolar division. This can be tested\nexperimentally by regulating microtubule anchoring.",
        "positive": "Faceting and flattening of emulsion droplets: a mechanical model: When cooled down, emulsion droplets stabilized by a frozen interface of\nalkane molecules and surfactants have been observed to undergo a spectacular\nsequence of morphological transformations: from spheres to faceted icosahedra,\ndown to flattened liquid platelets. While generally ascribed to the interplay\nbetween the elasticity of the frozen interface and surface tension, the\nphysical mechanisms underpinning these transitions have remained elusive,\ndespite different theoretical pictures having been proposed in recent years. In\nthis article, we introduce a comprehensive mechanical model of morphing\nemulsion droplets, which quantitatively accounts for various experimental\nobservations, including the scaling behavior of the faceting transition. Our\nanalysis highlights the role of gravity and the spontaneous curvature of the\nfrozen interface in determining the specific transition pathway."
    },
    {
        "anchor": "Wedge filling, cone filling and the strong fluctuation regime: Interfacial fluctuation effects occuring at wedge and cone filling\ntransitions are investigated and shown to exhibit very different\ncharacteristics. For both geometries we show how the conditions for observing\ncritical (continuous) filling are much less restrictive than for critical\nwetting, which is known to require fine tuning of the Hamaker constants. Wedge\nfilling is critical if the wetting binding potential does not exhibit a local\nmaximum, whilst conic filling is critical if the integrated strength of the\npotential is attractive. This latter scenario is particularly encouraging for\nfuture experimental studies. Using mean-field and effective Hamiltonian\napproaches, which allow for breather-mode fluctuations which translate the\ninterface up and down the sides of the confining geometry, we are able to\ncompletely classify the possible critical behaviour (for purely thermal\ndisorder). For the three dimensional wedge, the interfacial fluctuations are\nvery strong and characterised by a universal roughness critical exponent\n$\\nu_{\\perp} =1/4$ independent of the range of the forces. For the physical\ndimensions d=2 and d=3, we show that the influence of the cone geometry on the\nfluctuations at critical filling is to mimic the analogous interfacial\nbehaviour occuring at critical wetting in the strong-fluctuation regime. In\nparticular, for d=3 and for quite arbitary choices of intermolecular potential,\nthe filling height and roughness show the same critical properties as those\npredicted for three dimensional critical wetting with short-ranged forces in\nthe large wetting parameter ($\\omega>2$) regime.",
        "positive": "Statics and dynamics of a cylindrical droplet under an external body\n  force: We study the rolling and sliding motion of droplets on a corrugated substrate\nby Molecular Dynamics simulations. Droplets are driven by an external body\nforce (gravity) and we investigate the velocity profile and dissipation\nmechanisms in the steady state. The cylindrical geometry allows us to consider\na large range of droplet sizes. The velocity of small droplets with a large\ncontact angle is dominated by the friction at the substrate and the velocity of\nthe center of mass scales like the square root of the droplet size. For large\ndroplets or small contact angles, however, viscous dissipation of the flow\ninside the volume of the droplet dictates the center of mass velocity that\nscales linearly with the size. We derive a simple analytical description\npredicting the dependence of the center of mass velocity on droplet size and\nthe slip length at the substrate. In the limit of vanishing droplet velocity we\nquantitatively compare our simulation results to the predictions and good\nagreement without adjustable parameters is found."
    },
    {
        "anchor": "Magnetoelastic instability in soft thin films: Ferromagnetic particles are incorporated in a thin soft elastic matrix. A\nlamella, made of this smart material, is studied experimentally and modeled. We\nshow herein that thin films can be actuated using an external magnetic field\napplied through the system. The system is found to be switchable since\nsubcritical pitchfork bifurcation is discovered in the beam shape when the\nmagnetic field orientation is modified. Strong magnetoelastic effects can be\nobtained depending on both field strength and orientation. Our results provide\nversatile ways to contribute to many applications from the microfabrication of\nactuators to soft robotics. As an example, we created a small synthetic octopus\npiloted by an external magnetic field.",
        "positive": "Salt Modulated Structure of Polyelectrolyte-Macroion Complex Fibers: The structure and stability of strongly charged complex fibers formed by\ncomplexation of a single long semi-flexible polyelectrolyte (PE) chain and many\noppositely charged spherical macroions are investigated numerically at the\nground-state level using a chain-sphere cell model. The model takes into\naccount chain elasticity as well as electrostatic interactions between charged\nspheres and chain segments. Using a numerical optimization method based on a\nperiodically repeated unit cell, we obtain fiber configurations that minimize\nthe total energy. The optimal configurations exhibit a variety of helical\nstructures for the arrangement of macroions including zig-zag, solenoidal and\nbeads-on-a-string patterns. These structures are determined by a competition\nbetween attraction between spheres and the PE chain (which favors chain\nwrapping around the spheres), chain bending and electrostatic repulsion between\nchain segments (which favor unwrapping of the chain), and the interactions\nbetween neighboring sphere-chain complexes which can be attractive or repulsive\ndepending on the system parameters such as medium salt concentration, macroion\ncharge and chain length per macroion (linker size). At about physiological salt\nconcentration, dense zig-zag patterns are found to be energetically most stable\nwhen parameters appropriate for the DNA-histone system in a chromatin fiber are\nadopted. In fact, the predicted fiber diameter in this regime is found to be\naround 30nm, which appears to agree with the thickness observed in in vitro\nexperiments on chromatin. We also find a macroion density of 5-6 per 11nm which\nagrees with the zig-zag or cross-linker models of chromatin. Since our study\ndeals primarily with a generic model, these findings suggest that\nchromatin-like structures should also be observable for PE-macroion complexes\nformed in solutions of DNA and synthetic nano-colloids of opposite charge."
    },
    {
        "anchor": "Adaptive Resolution Molecular Dynamics Simulation: Changing the Degrees\n  of Freedom on the Fly: We present a new adaptive resolution technique for efficient particle-based\nmultiscale molecular dynamics (MD) simulations. The presented approach is\ntailor-made for molecular systems where atomistic resolution is required only\nin spatially localized domains whereas a lower mesoscopic level of detail is\nsufficient for the rest of the system. Our method allows an on-the-fly\ninterchange between a given molecule's atomic and coarse-grained level of\ndescription, enabling us to reach large length and time scales while spatially\nretaining atomistic details of the system. The new approach is tested on a\nmodel system of a liquid of tetrahedral molecules. The simulation box is\ndivided into two regions: one containing only atomistically resolved\ntetrahedral molecules, the other containing only one particle coarse-grained\nspherical molecules. The molecules can freely move between the two regions\nwhile changing their level of resolution accordingly. The coarse-grained and\nthe atomistically resolved systems have the same statistical properties at the\nsame physical conditions.",
        "positive": "Two-dimensional fluid with competing interactions exhibiting microphase\n  separation: theory for bulk and interfacial properties: Colloidal particles that are confined to an interface such as the air-water\ninterface are an example of a two-dimensional fluid. Such dispersions have been\nobserved to spontaneously form cluster and stripe morphologies in certain\nsystems with isotropic pair potentials between the particles, due to the fact\nthat the pair interaction between the colloids has competing attraction and\nrepulsion over different length scales. Here we present a simple density\nfunctional theory for a model of such a two-dimensional fluid. The theory\npredicts a bulk phase diagram exhibiting cluster, stripe and bubble modulated\nphases, in addition to homogeneous fluid phases. Comparing with simulation\nresults for this model from the literature, we find that the theory is\nqualitatively reliable. The model allows for a detailed investigation of the\nstructure of the fluid and we are able to obtain simple approximate expressions\nfor the static structure factor and for the length scale characterising the\nmodulations in the microphase separated phases. We also investigate the\nbehaviour of the system under confinement between two parallel hard walls. We\nfind that the confined fluid phase behaviour can be rather complex."
    },
    {
        "anchor": "Polyelectrolyte Networks: Elasticity, Swelling, and the Violation of the\n  Flory - Rehner Hypothesis: This paper discusses the elastic behavior of polyelectrolyte networks. The\ndeformation behavior of single polyelectrolyte chains is discussed. It is shown\nthat a strong coupling between interactions and chain elasticity exists. The\ntheory of the complete crosslinked networks shows that the Flory - Rehner -\nHypothesis (FRH) does not hold. The modulus contains contributions from the\nclassical rubber elasticity and from the electrostatic interactions. The\nequilibrium degree of swelling is estimated by the assumption of a\n$c^{*}$-network.",
        "positive": "Hindered nematic alignment of hematite spindles in viscoelastic matrices: The viscoelastic behavior of composites consisting of spindle-shaped hematite\nparticles in poly-N-isopropylacrylamide hydrogels is investigated both, by\nmeans of rheological oscillatory shear experiments, and the field-induced\nalignment of these mesoscale, anisotropic particles in external magnetic\nfields. Due to their magnetic moment and magnetic anisotropy hematite spindles\nalign with their long axis perpendicular to the direction of an external\nmagnetic field. The field induced torque acting on the magnetic particles leads\nto an elastic deformation of the hydrogel matrix. Thus, the field-dependent\norientational distribution functions of anisotropic particles acting as\nmicrorheological probes depend on the elastic modulus of the hydrogel matrix.\nThe orientational distribution functions are determined by means of Small Angle\nX-ray Scattering experiments in presence of external magnetic fields. With\nincreasing elasticity of the hydrogels, tuned via the polymer volume fraction\nand the crosslinking density, the field-induced alignment of these anisotropic,\nmagnetic particles is progressively hindered. The microrheological results are\nin accordance to macrorheological experiments indicating increasing elasticity\nwith increasing flux density of an external field."
    },
    {
        "anchor": "Role of rotational inertia for collective phenomena in active matter: We investigate the effect of rotational inertia on the collective phenomena\nof underdamped active systems and show that the increase of the moment of\ninertia of each particle favors non-equilibrium phase coexistence, known as\nmotility induced phase separation, and counteracts its suppression due to\ntranslational inertia. Our conclusion is supported by a non-equilibrium phase\ndiagram (in the plane spanned by rotational inertial time and translational\ninertial time) whose transition line is understood theoretically through\nscaling arguments. In addition, rotational inertia increases the correlation\nlength of the spatial velocity correlations in the dense cluster. The fact that\nrotational inertia enhances collective phenomena, such as motility induced\nphase separation and spatial velocity correlations, is strongly linked to the\nincrease of rotational persistence. Moreover, large moments of inertia induce\nnon-monotonic temporal (cross) correlations between translational and\nrotational degrees of freedom truly absent in non-equilibrium systems.",
        "positive": "Directed Motion of Elongated Active Polymers: Previous work shows that a net directed motion arises from a system of\nindividual particles undergoing run-and-tumble dynamics in the presence of an\narray of asymmetric barriers. Here, we show that when the individual particle\nis replaced by a chain of particles linked to each other by spring forces\n(polymer), the rectification is enhanced. It is found that the rectification\nincreases when the number of particles in each polymer, as well as its length,\nincreases. In addition, the rectification increases when the size of the\nopening between neighboring funnel tips, lo, decreases. Interestingly, if the\nconformal entropic difference exceeds the thermal diffusion, net directed\nmotion is observed even when the run-and-tumble dynamics approaches Brownian\nmotion. Also, when the inelastic collisions between the particles and the\nbarriers are replaced by elastic collisions, a reversed rectification is\nobserved."
    },
    {
        "anchor": "Breakdown of Elasticity in Amorphous Solids: What characterises a solid is its way to respond to external stresses.\nOrdered solids, such crystals, display an elastic regime followed by a plastic\none, both well understood microscopically in terms of lattice distortion and\ndislocations. For amorphous solids the situation is instead less clear, and the\nmicroscopic understanding of the response to deformation and stress is a very\nactive research topic. Several studies have revealed that even in the elastic\nregime the response is very jerky at low temperature, resembling very much the\none of disordered magnetic materials. Here we show that in a very large class\nof amorphous solids this behaviour emerges by decreasing the temperature as a\nphase transition where standard elastic behaviour breaks down. At the\ntransition all non-linear elastic modulii diverge and standard elasticity\ntheory does not hold anymore. Below the transition the response to deformation\nbecomes history and time-dependent.",
        "positive": "Dynamical symmetry breaking in transport through molecules: We analyze the interplay between vibrational and electronic degrees of\nfreedom in charge transport across a molecular single-electron transistor. We\nfocus on the wide class of molecules which possess quasi-degenerate vibrational\neigenstates, while no degeneracy occurs for their anionic configuration. We\nshow that the combined effect of a thermal environment and coupling to leads,\ninvolving tunneling events charging and discharging the molecule, leads to a\ndynamical symmetry breaking where quasi-degenerate eigenstates acquire\ndifferent occupations. This imbalance gives rise to a characteristic asymmetry\nof the current versus an applied gate voltage."
    },
    {
        "anchor": "Elastic turbulence in two-dimensional cross-slot viscoelastic flows: We report evidence of irregular unsteady flow of two-dimensional polymer\nsolutions in the absence of inertia in cross-slot geometry using numerical\nsimulations of Oldroyd-B model. By exploring the transition to time-dependent\nflow versus both the fluid elasticity and the polymer concentration, we find\nperiodic behaviour close to the instability threshold and more complex flows at\nlarger elasticity, in agreement with experimental findings. For high enough\nelasticity we obtain dynamics pointing to elastic turbulence, with temporal\nspectra of velocity fluctuations showing a power-law decay, of exponent in\nbetween -3 and -2, and probability density functions of velocity fluctuations\nthat weakly deviate from Gaussianity while high non-Gaussian tails characterise\nthose of local accelerations.",
        "positive": "Force distributions and force chains in random stiff fiber networks: We study the elasticity of random stiff fiber networks. The elastic response\nof the fibers is characterized by a central force stretching stiffness as well\nas a bending stiffness that acts transverse to the fiber contour. Previous\nstudies have shown that this model displays an anomalous elastic regime where\nthe stretching mode is fully frozen out and the elastic energy is completely\ndominated by the bending mode. We demonstrate by simulations and scaling\narguments that, in contrast to the bending dominated \\emph{elastic energy}, the\nequally important \\emph{elastic forces} are to a large extent stretching\ndominated. By characterizing these forces on microscopic, mesoscopic and\nmacroscopic scales we find two mechanisms of how forces are transmitted in the\nnetwork. While forces smaller than a threshold $F_c$ are effectively balanced\nby a homogeneous background medium, forces larger than $F_c$ are found to be\nheterogeneously distributed throughout the sample, giving rise to highly\nlocalized force-chains known from granular media."
    },
    {
        "anchor": "Crystallization and topology-induced dynamical heterogeneities in soft\n  granular clusters: Soft-granular media such as dense emulsions, foams or tissues tend to exhibit\neither fluid- or solid-like properties depending on the applied stresses.\nHowever, the internal dynamics of soft granular systems bound by closed\ninterfaces is poorly understood, while it remains of significant interest in\ndiverse fields ranging from material science (porous materials) and tissue\nengineering (granular bioinks) to developmental biology (embryos, organoids)\nand medicine (circulating tumor cell clusters). Here, we report the spontaneous\noccurrence of crystalline-like hexagonal structures within soft granular\nclusters which self-organize under external flow. We use a densely packed\ndouble emulsion as a model soft granular material to produce clusters of sizes\nof 20-40 grains (droplets). We find that, optimally, the crystallites emerge\nunder weak flows, when the internal shear stresses slightly agitate the system\nallowing internal rearrangements. Excessive flows destroy the delicate\ncrystalline structure and lead to constant internal recirculations, i.e.,\neffective fluidization of the granular medium. Upon subjecting the clusters to\ncycles of constriction and relaxation/expansion, we also find differences\nbetween the behaviours of two groups of droplets: those within the inner part\nof the cluster and those at its rim, with the latter subjected to larger\ndeformations and less frequent rearrangements, effectively acting as an elastic\nsolid-like membrane around the inner fluid-like core. This structural-dynamical\nheterogeneity appears to be of purely topological origin and as such we expect\nit to remain universal in various types of soft granular clusters or jets\nincluding also cell aggregates, organoids or bioprinted tissues.",
        "positive": "Are stress-free membranes really 'tensionless'?: In recent years it has been argued that the tension parameter driving the\nfluctuations of fluid membranes, differs from the imposed lateral stress, the\n'frame tension'. In particular, stress-free membranes were predicted to have a\nresidual fluctuation tension. In the present paper, this argument is\nreconsidered and shown to be inherently inconsistent -- in the sense that a\nlinearized theory, the Monge model, is used to predict a nonlinear effect.\nFurthermore, numerical simulations of one-dimensional stiff membranes are\npresented which clearly demonstrate, first, that the internal 'intrinsic'\nstress in membranes indeed differs from the frame tension as conjectured, but\nsecond, that the fluctuations are nevertheless driven by the frame tension.\nWith this assumption, the predictions of the Monge model agree excellently with\nthe simulation data for stiffness and tension values spanning several orders of\nmagnitude."
    },
    {
        "anchor": "Collective dynamics and phase transition of active matter in presence of\n  orientation adapters: In this work, the orientation adapter, a species of active particles that\nadapt their direction of motion from the other active particles, is introduced.\nThe orientation adapters exist besides the usual Vicsek-like particles; both\nare self-driven, however, follow different interaction rules. We have studied\nthe dynamics in high speed of the particles keeping dissimilar speeds for these\ndifferent species. The effect of orientation adapters on the collective\nbehaviour of the system is explored in this model. The orientational\norder-disorder phase transition is mainly studied in such systems. First, for\nequal density of both species, when the adapter speed $v_a=1.2v_0$ and usual\nparticles speed $v_0=1.0$, both adapters and the usual particles form dense\ntravelling bands and move in the same direction. Near the transition point,\nsuch bands appear and disappear over time, giving rise to the co-existence of\ntwo phases. The adapters and the usual particles both undergo a discontinuous\ntransition. The nature of the transition is further confirmed by the existence\nof hysteresis in the order parameter under a continuously varying noise field.\nHowever, when the adapter velocity becomes much higher than the usual SPPs $v_a\n\\approx 7v_0$, the formation of travelling bands disappears from the system,\nand the transition becomes continuous. The density ratio is also varied,\nkeeping the velocities constant, and the phase transition is studied. For a\nhigh adapter velocity with $v_a=10v_0$, the continuous transition is found with\nlow-density values of the adapters. The critical exponents related to the\ncontinuous transition are also determined.",
        "positive": "The Influence of Substrate Structure on Membrane Adhesion: We consider a membrane both weakly and strongly adhering to a geometrically\nstructured substrate. The interaction potential is assumed to be local, via the\nDeryagin approximation, and harmonic. Consequently, we can analytically\ndescribe a variety of different geometries: as well as randomly rough\nself-affine surfaces, smooth substrates interrupted by an isolated cylindrical\npit, a single elongated trench or a periodic array of trenches are\ninvestigated. We present more general expressions for the adhesion energy and\nmembrane configuration in Fourier space and find that, compared to planar\nsurfaces, the adhesion energy decreases. We also highlight the possibility of\novershoots occurring in the membrane profile and look at its degree of\npenetration into surface indentations."
    },
    {
        "anchor": "A novel setup coupling space-resolved dynamic light scattering and\n  rheometetry unveils the heterogeneous flow field and non-affine dynamics in\n  startup shear of a gel: We present a new light scattering setup coupled to a commercial rheometer\noperated in the plate-plate geometry. The apparatus allows the microscopic\ndynamics to be measured, discriminating between the contribution due to the\naffine deformation and additional mechanisms, such as plasticity. Light\nbackscattered by the sample is collected using an imaging optical layout,\nthereby allowing the average flow velocity and the microscopic dynamics to be\nprobed with both spatial and temporal resolution. We successfully test the\nsetup by measuring the Brownian diffusion and flow velocity of diluted\ncolloidal suspensions, both at rest and under shear. The potentiality of the\napparatus are explored in the startup shear of a biogel. For small shear\ndeformations, $\\gamma \\le 2\\%$, the rheological response of the gel is linear.\nHowever, striking deviations from affine flow are seen from the very onset of\ndeformation, due to temporally and spatially heterogeneous rearrangements\nbearing intriguing similarities with a stick-slip process.",
        "positive": "Nanometer scale resolution, multi-channel separation of spherical\n  particles in a rocking ratchet with increasing barrier heights: We present a nanoparticle size-separation device based on a nanofluidic\nrocking Brownian motor. It features a ratchet-shaped electrostatic particle\npotential with increasing barrier heights along the particle transport\ndirection. The sharp drop of the particle current with barrier height is\nexploited to separate a particle suspension into multiple sub-populations. By\nsolving the Fokker--Planck equation, we show that the physics of the separation\nmechanism is governed by the energy landscape under forward tilt of the\nratchet. For a given device geometry and sorting duration, the applied force is\nthus the only tunable parameter to increase the separation resolution. For the\nexperimental conditions of 3.5 V applied voltage and 20 s sorting, we predict a\nseparation resolution of $\\sim 2$ nm, supported by experimental data for\nseparating spherical gold particles of nominal 80 and 100 nm diameters."
    },
    {
        "anchor": "Take-off of small Leidenfrost droplets: We put in evidence the unexpected behaviour of Leidenfrost droplets at the\nlater stage of their evaporation. We predict and observe that, below a critical\nsize $R_l$, the droplets spontaneously take-off due to the breakdown of the\nlubrication regime. We establish the theoretical relation between the droplet\nradius and its elevation. We predict that the vapour layer thickness increases\nwhen the droplets become smaller. A satisfactory agreement is found between the\nmodel and the experimental results performed on droplets of water and of\nethanol.",
        "positive": "Contact Topology and the Classification of Disclination Lines in\n  Cholesteric Liquid Crystals: We give a topological classification of defect lines in cholesteric liquid\ncrystals using methods from contact topology. By focusing on the role played by\nthe chirality of the material, we demonstrate a fundamental distinction between\n`tight' and `overtwisted' disclination lines not detected by standard homotopy\ntheory arguments. The classification of overtwisted lines is the same as\nnematics, however, we show that tight disclinations possess a topological layer\nnumber that is conserved as long as the twist is nonvanishing. Finally, we\nobserve that chirality frustrates the escape of removable defect lines, and\nexplain how this frustration underlies the formation of several structures\nobserved in experiments."
    },
    {
        "anchor": "Alignment induced re-configurable walls for patterning and assembly of\n  liquid crystal skyrmions: Skyrmions have attracted rapidly growing interest due to their topological\nproperties and unique aspects for potential novel applications such as data\nstorage and soft robotics. They can also serve as key elements for materials by\ndesign, self-assembly, and functional soft materials. While not real particles,\nthese skyrmions behave like particles-they interact with each other and can be\nactuated by means of electric field, surface anchoring, and light. On the other\nhand, they are field configurations which have properties not possessed by real\nparticles. Here, we show that, by means of alignment induced attractive and\nrepulsive walls, skyrmions in chiral nematic liquid crystals can be precisely\ncontrolled and programmed to serve as suitable building blocks for the\nrealization of the above goals. Our work may stimulate new experimental efforts\nand concomitant applications in this direction.",
        "positive": "Bridging cumulative and non-cumulative geometric frustration response\n  via a frustrated $N$-state spin system: The resolution of geometric frustration in systems with continuous degrees of\nfreedom often involves a cooperative inhomogeneous response and super-extensive\nenergy scaling. In contrast, the frustration in frustrated Ising-like spin\nsystems is resolved uniformly. In this work we bridge between these two\nextremes by studying a frustrated model composed of N-state spins, and varying\nN. The expected cooperative response, observed for large N, is strongly\nattenuated as N is reduced, in a non-trivial way. Moderate N values show unique\ntopological-like phases not observed before in frustrated models."
    },
    {
        "anchor": "Polymorphic phase transitions in bulk triglyceride mixtures: Triacylglycerols (TAGs) are among the most important ingredients in food,\ncosmetic and pharmaceutical products. Many physical properties of such\nproducts, incl. morphology, texture and rheology, are determined by the phase\nbehaviour of the included TAGs. Triglycerides are also of special interest for\nthe production of solid lipid nanoparticles, applied for controlled drug\ndelivery and for encapsulation of bioactive ingredients. In this paper, we\nstudy the polymorphic behaviour of complex TAG mixtures, composed of 2 to 6\nmixed TAGs, by differential scanning calorimetry and X-ray scattering\ntechniques, aiming to reveal the general rules for their phase behaviour upon\ncooling and heating. The results show that two or more coexisting phases form\nupon solidification $(\\alpha$, $\\beta'$ and/or $\\beta)$, the number of which\ndepends strongly on the cooling rate and on the number of components in the\nmixture. No completely miscible $\\alpha$- or $\\beta'$-phases were observed. The\nstructure of the most stable $\\beta$ polymorphs, formed upon subsequent heating\nof the solidified samples, does not depend on the thermal history of the\nsamples. For all mixtures studied, we observed one-component $\\beta$ domains,\ncoexisting with binary mixed $\\beta$ domains with composition and structure\nwhich do not depend on the specific TAG ratio in the mixture. In other words,\nfor a mixture with $k$ saturated TAGs we observed $(2k-1)$ different $\\beta$\nphases. These conclusions provide some predictive power when analysing the\nphase transition properties of TAG mixtures.",
        "positive": "Magnetic Polymer Models for Epigenomic Organisation and Phase Separation: The genetic instructions stored in the genome require an additional layer of\ninformation to robustly determine cell fate. This additional regulation is\nprovided by the interplay between chromosome-patterning biochemical\n(\"epigenetic\") marks and three-dimensional genome folding. Yet, the physical\nprinciples underlying the dynamical coupling between three-dimensional genomic\norganisation and one-dimensional epigenetic patterns remain elusive. To shed\nlight on this issue, here we study by mean field theory and Brownian dynamics\nsimulations a magnetic polymer model for chromosomes, where each monomer\ncarries a dynamic epigenetic mark. At the single chromosome level, we show that\na first order transition describes the unlimited spreading of epigenetic marks,\na phenomenon that is often observed in vivo. At the level of the whole nucleus,\nexperiments suggest chromosomes form micro-phase separated compartments with\ndistinct epigenetic marks. We here discover that for a melt of magnetic\npolymers such a morphology is thermodynamically unstable, but can be stabilised\nby a non- equilibrium and ATP-mediated epigenetic switch between different\nmonomer states."
    },
    {
        "anchor": "Description of hard sphere crystals and crystal-fluid interfaces: a\n  critical comparison between density functional approaches and a phase field\n  crystal model: In materials science the phase field crystal approach has become popular to\nmodel crystallization processes. Phase field crystal models are in essence\nLandau-Ginzburg-type models, which should be derivable from the underlying\nmicroscopic description of the system in question. We present a study on\nclassical density functional theory in three stages of approximation leading to\na specific phase field crystal model, and we discuss the limits of\napplicability of the models that result from these approximations. As a test\nsystem we have chosen the three--dimensional suspension of monodisperse hard\nspheres. The levels of density functional theory that we discuss are\nfundamental measure theory, a second-order Taylor expansion thereof, and a\nminimal phase-field crystal model. We have computed coexistence densities,\nvacancy concentrations in the crystalline phase, interfacial tensions and\ninterfacial order parameter profiles, and we compare these quantities to\nsimulation results. We also suggest a procedure to fit the free parameters of\nthe phase field crystal model.",
        "positive": "Two-scale evolution during shear reversal in dense suspensions: We use shear reversal simulations to explore the rheology of dense,\nnon-Brownian suspensions, resolving lubrication forces between neighbouring\nparticles and modelling particle surface contacts. The transient stress\nresponse to an abrupt reversal of the direction of shear shows\nrate-independent, nonmonotonic behaviour, capturing the salient features of the\ncorresponding classical experiments. Based on analyses of the hydrodynamic and\nparticle contact stresses and related contact networks, we demonstrate distinct\nresponses at small and large strains, associated with contact breakage and\nstructural re-orientation, respectively, emphasising the importance of particle\ncontacts. Consequently, the hydrodynamic and contact stresses evolve over\ndisparate strain scales and with opposite trends, resulting in nonmonotonic\nbehaviour when combined. We further elucidate the roles of particle roughness\nand repulsion in determining the microstructure and hence the stress response\nat each scale."
    },
    {
        "anchor": "Effective potentials induced by mixtures of patchy and hard co-solutes: The addition of co-solutes to colloidal suspensions is often employed to\ninduce tunable depletion interactions. In this work we investigate effective\ncolloidal interactions arising from binary co-solute mixtures of hard spheres\nand patchy particles. By changing the relative concentration of the two\nspecies, we show that the resulting effective potential $V_\\text{eff}$\ncontinuously changes from the one obtained for a single-component hard sphere\nco-solute to that mediated by the single-component patchy particle co-solute.\nInterestingly, we find that, independently of the relative concentration of the\ntwo components, the resulting $V_\\text{eff}$ is additive, i.e., it is\nwell-described by the linear combination of the effective interactions mediated\nby respective pure co-solutes. However, a breakdown of the additivity occurs\nwhen the co-solute mixture is close to the onset of a demixing transition.\nThese results represent a step forward in understanding and predicting\ncolloidal behaviour in complex and crowded environments and for exploiting this\nknowledge to design targeted colloidal superstructures.",
        "positive": "Comparison of empirical and particle force-based density segregation\n  models: The empirical and particle force-based models of granular segregation due to\ndensity differences among the species are compared in this work. Dependency of\nthe empirical segregation parameters on the initial configuration, the\nobservation time duration, inclination angle, and mixture composition are\ndiscussed in detail. The parameters obtained from empirical models are used to\npredict the steady-state concentration profiles for different density ratios\nand compositions. In addition, we utilize the predictions from the particle\nforce-based segregation model and compare them with the predictions of the\nempirical segregation models. Our results show that the linear empirical\nsegregation model predictions agree well with the simulation results for\nmixtures rich in light species where as quadratic empirical segregation model\nworks better for mixtures rich in heavy species. Particle force-based\nsegregation model, on the other hand, seems to be in very good agreement with\nthe DEM simulation data across all mixture compositions."
    },
    {
        "anchor": "Robust nonequilibrium pathways to microcompartment assembly: Cyanobacteria sequester photosynthetic enzymes into microcompartments which\nfacilitate the conversion of carbon dioxide into sugars. Geometric similarities\nbetween these structures and self-assembling viral capsids have inspired models\nthat posit microcompartments as stable equilibrium arrangements of the\nconstituent proteins. Here we describe a different mechanism for\nmicrocompartment assembly, one that is fundamentally nonequilibrium and yet\nhighly reliable. This pathway is revealed by simulations of a molecular model\nresolving the size and shape of a cargo droplet, and the extent and topography\nof an elastic shell. The resulting metastable microcompartment structures\nclosely resemble those of carboxysomes, with a narrow size distribution and\nfaceted shells. The essence of their assembly dynamics can be understood from a\nsimpler mathematical model that combines elements of classical nucleation\ntheory with continuum elasticity. These results highlight important control\nvariables for achieving nanoscale encapsulation in general, and for modulating\nthe size and shape of carboxysomes in particular.",
        "positive": "Model-free thermodynamics of fluid vesicles: Motivated by a long-standing debate concerning the nature and interrelations\nof surface-tension variables in fluid membranes, we reformulate the\nthermodynamics of a membrane vesicle as a generic two-dimensional finite system\nenclosing a three-dimensional volume. The formulation is shown to require two\ntension variables, conjugate to the intensive constraints of area per molecule\nand volume-to-area ratio. We obtain the relation between these two variables in\nvarious scenarios, as well as their correspondence to other definitions of\ntension variables for membranes. Several controversies related to membrane\ntension are thereby resolved on a model-free thermodynamic level. The\nthermodynamic formulation may be useful also for treating large-scale\nproperties of vesicles that are insensitive to the membrane's detailed\nstatistical mechanics and interactions."
    },
    {
        "anchor": "Crowding competes with trapping to enhance interfacial diffusion: Diffusion in the crowded environments of the biological membranes or\nmaterials interfaces often involves intermittent binding to surface proteins or\ndefects. To account for this situation we study a 2-dimensional lattice gas in\na field of immobilized traps. Using kinetic Monte Carlo simulations, we\ncalculate the effective diffusion coefficient in the long-time limit as a\nfunction of the traps and particle densities. We find a remarkable result - an\nincrease of the diffusion coefficient with particle density, an effect that we\ncoin as crowding-enhanced diffusion. We rationalize this result using scaling\narguments and the master equation approach.",
        "positive": "Stability of Quasicrystals Composed of Soft Isotropic Particles: Quasicrystals whose building blocks are of mesoscopic rather than atomic\nscale have recently been discovered in several soft-matter systems. Contrary to\nmetallurgic quasicrystals whose source of stability remains a question of great\ndebate to this day, we argue that the stability of certain soft-matter\nquasicrystals can be directly explained by examining a coarse-grained free\nenergy for a system of soft isotropic particles. We show, both theoretically\nand numerically, that the stability can be attributed to the existence of two\nnatural length scales in the pair potential, combined with effective three-body\ninteractions arising from entropy. Our newly gained understanding of the\nstability of soft quasicrystals allows us to point at their region of stability\nin the phase diagram, and thereby may help control the self-assembly of\nquasicrystals and a variety of other desired structures in future experimental\nrealizations."
    },
    {
        "anchor": "Effective interactions between like-charged macromolecules: We investigate, within a local density functional theory formalism, the\ninteractions between like-charged polyions immersed in a confined electrolyte.\nWe obtain a simple condition for a repulsive effective pair potential, that can\nbe related to the thermodynamic stability criterion of the uncharged\ncounterpart of microscopic species constituting the electrolyte. Under the same\ncondition, the phenomenon of charge inversion (over-charging), where the\npolyion bare charge is over-screened by its electric double layer, is shown to\nbe impossible. These results hold beyond standard mean-field theories (such as\nPoisson-Boltzmann or Modified Poisson-Boltzmann approaches).",
        "positive": "Direct observation of pore collapse and tensile stress generation on\n  pore wall due to salt crystallization: The generation of stress in a pore due to salt crystallization is generally\nanalysed as a compressive stress generation mechanism using the concept of\ncrystallization pressure. We report on a completely different stress generation\nmechanism. In contrast with the classical picture where the crystal pushes the\npore wall, the crystal growth leads to the generation of a local tensile\nstress. This tensile stress occurs next to a region where a compressive stress\nis generated, thus inducing also shear stresses. The tensile stress generation\nis attributed to capillary effects in the thin film confined between the\ncrystal and the pore wall. These findings are obtained from direct optical\nobservations in model pores where the tensile stress generation results in the\ncollapse of the pore region located between the crystal and the pore dead-end.\nThe experiments also reveal other interesting phenomena, such as the hyperslow\ndrying in PDMS channels or the asymmetrical growth of the crystal during the\ncollapse."
    },
    {
        "anchor": "Tuning the porosity of bimetallic nanostructures by a soft templating\n  approach: We use hexagonal mesophases made of oil-swollen surfactant-stabilized tubes\narranged on a triangular lattice in water and doped with metallic salts as\ntemplates for the radiolytic synthesis of nanostructures. The nanostructures\nformed in this type of soft matrix are bimetallic palladium-platinum porous\nnanoballs composed of 3D-connected nanowires, of typical thickness 2.5 nm,\nforming hexagonal cells. We demonstrate using electron microscopy and\nsmall-angle X-ray scattering that the pore size of the nanoballs is directly\ndetermined by the diameter of the oil tube of the doped mesophases, which we\nhave varied in a controlled fashion from 10 to 55 nm. Bimetallic nanostructures\ncomprising various proportions of palladium and platinum can be synthesized.\nTheir alloy structure was evidenced by X-ray photoelectron spectroscopy,\nenergy-dispersive X-ray spectroscopy, and high-angular dark field scanning\ntransmission electron microscopy experiments. Our templating approach allows\ntherefore the synthesis of bimetallic nanoballs of tunable porosity and\ncomposition.",
        "positive": "Liquid-liquid phase transition of water in hydrophobic and hydrophilic\n  pores: Effect of confinement on the liquid-liquid transition of water are studied by\nsimulations in the Gibbs ensemble. Upon cooling along the liquid-vapor\ncoexistence curve, confined water undergoes transition from normal to strongly\ntetrahedral water via a first order phase transition (as in the bulk) or in a\ncontinuous way in dependence on pore hydrophilicity. In all cases, transition\ntemperature is only slightly shifted by the confinement. This agrees with the\nexperimentally observed weak effect of confinement on the temperature of the\nfragile-to-strong transition of water."
    },
    {
        "anchor": "Anomalous glassy dynamics in simple models of dense biological tissue: In order to understand the mechanisms for glassy dynamics in biological\ntissues and shed light on those in non-biological materials, we study the\nlow-temperature disordered phase of 2D vertex-like models. Recently it has been\nnoted that vertex models have quite unusual behavior in the zero-temperature\nlimit, with rigidity transitions that are controlled by residual stresses and\ntherefore exhibit very different scaling and phenomenology compared to\nparticulate systems. Here we investigate the finite-temperature phase of\ntwo-dimensional Voronoi and Vertex models, and show that they have highly\nunusual, sub-Arrhenius scaling of dynamics with temperature. We connect the\nanomalous glassy dynamics to features of the potential energy landscape\nassociated with zero-temperature inherent states.",
        "positive": "Scanning camera for continuous-wave acoustic holography: We present a system for measuring the amplitude and phase profiles of the\npressure field of a harmonic acoustic wave with the goal of reconstructing the\nvolumetric sound field. Unlike optical holograms that cannot be reconstructed\nexactly because of the inverse problem, acoustic holograms are completely\nspecified in the recording plane. We demonstrate volumetric reconstructions of\nsimple arrangements of objects using the Rayleigh-Sommerfeld diffraction\nintegral, and introduce a technique to analyze the dynamic properties of\ninsonated objects."
    },
    {
        "anchor": "The F\u00f6ppl-von K\u00e1rm\u00e1n equations of elastic plates with initial\n  stress: Initially stressed plates are widely used in modern fabrication techniques,\nsuch as additive manufacturing and UV lithography, for their tunable morphology\nby application of external stimuli. In this work, we propose a formal\nasymptotic derivation of the F\\\"{o}ppl-von K\\'{a}rm\\'{a}n equations for an\nelastic plate with initial stresses, using the constitutive theory of nonlinear\nelastic solids with initial stresses under the assumptions of incompressibility\nand material isotropy. Compared to existing works, our approach allows to\ndetermine the morphological transitions of the elastic plate without\nprescribing the underlying target metric of the unstressed state of the elastic\nbody. We explicitly solve the derived FvK equations in some physical problems\nof engineering interest, discussing how the initial stress distribution drives\nthe emergence of spontaneous curvatures within the deformed plate. The proposed\nmathematical framework can be used to tailor shape on demand, with applications\nin several engineering fields ranging from soft robotics to 4D printing.",
        "positive": "Tuning Colloidal Reactions: The precise control of complex reactions is critical for biological processes\nranging from cell division to metabolism. Synthetic analogues of living\nmaterials suffer from our inability to tune chemical reactions with precise\noutcomes. Here, we leverage differentiable simulators to design nontrivial\nreaction pathways in colloidal assemblies. By optimizing interactions between\nreactants and substrates, we achieve controlled disassembly of octahedral and\nicosahedral shells. As a potential engineering target, we design a reaction\nthat provokes the release of a small particle trapped in a shell."
    },
    {
        "anchor": "Atomic Level Green-Kubo Stress Correlation Function for a Model Crystal:\n  An Insight into Molecular Dynamics Results on a Model Liquid: In order to get insight into the connection between the vibrational dynamics\nand the atomic level Green-Kubo stress correlation function in liquids we\nconsider this connection in a model crystal instead. Of course, vibrational\ndynamics in liquids and crystals are quite different and it is not expected\nthat the results obtained on a model crystal should be valid for liquids.\nHowever, these considerations provide a benchmark to which the results of the\nprevious molecular dynamics simulations can be compared. Thus, assuming that\nvibrations are plane waves, we derive analytical expressions for the atomic\nlevel stress correlation functions in the classical limit and analyze them.\nThese results provide, in particular, a recipe for analysis of the atomic level\nstress correlation functions in Fourier space and extraction of the wavevector\nand frequency dependent information. We also evaluate the energies of the\natomic level stresses. Obtained energies are significantly smaller than the\nenergies that were obtained in MD simulations of liquids previously. This\nresult suggests that the average energies of the atomic level stresses in\nliquids and glasses are largely determined by the structural disorder. We\ndiscuss this result in the context of equipartition of the atomic level stress\nenergies. Analysis of the previously published data suggests that it is\npossible to speak about configurational and vibrational contributions to the\naverage energies of the atomic level stresses in a glass state. However, this\nseparation in a liquid state is problematic. We also consider peak broadening\nin the pair distribution function with increase of distance. We find that peak\nbroadening (by ~40%) occurs due to the transverse vibrational modes, while\ncontribution from the longitudinal modes does not change with distance.\nFinally, we introduce and consider atomic level transverse current correlation\nfunction.",
        "positive": "Model for the resistance force acting on circular bodies in the\n  imminence of rolling: The laws of friction are reasonably well understood for the case of blocks in\ncontact with rough plane surfaces. However, as far as bodies with circular\nsections are concerned, the physics of friction becomes more involving and it\nis not possible to adopt a simple conceptual framework to explain all\nphenomena. In particular, there is no approach so far to the problem of the\nresistance force that opposes to circular bodies that remain at rest while\nacted upon by small forces. Here we fill this gap by introducing a mechanical\nmodel based on both the elasticity theory and Hertz contact mechanics. Our\napproach furnishes a quantitative expression for the critical force beyond\nwhich rest can no longer be maintained. Besides confirming the expected\nproportionality of the resistance force with the load, our result contains no\nfree parameters and is expressed solely in terms of physical properties of the\nproblem, such as the pressure of the body per unit of superficial area, a\nrelation between the Young modulus of the surface and its Poisson ratio, and\nthe symmetry of the contact."
    },
    {
        "anchor": "Measuring the energy landscape roughness and the transition state\n  location of biomolecules using single molecule mechanical unfolding\n  experiments: Single molecule mechanical unfolding experiments are beginning to provide\nprofiles of the complex energy landscape of biomolecules. In order to obtain\nreliable estimates of the energy landscape characteristics it is necessary to\ncombine the experimental measurements with sound theoretical models and\nsimulations. Here, we show how by using temperature as a variable in mechanical\nunfolding of biomolecules in laser optical tweezer or AFM experiments the\nroughness of the energy landscape can be measured without making any\nassumptions about the underlying reaction oordinate. The efficacy of the\nformalism is illustrated by reviewing experimental results that have directly\nmeasured roughness in a protein-protein complex. The roughness model can also\nbe used to interpret experiments on forced-unfolding of proteins in which\ntemperature is varied. Estimates of other aspects of the energy landscape such\nas free energy barriers or the transition state (TS) locations could depend on\nthe precise model used to analyze the experimental data. We illustrate the\ninherent difficulties in obtaining the transition state location from loading\nrate or force-dependent unfolding rates. Because the transition state moves as\nthe force or the loading rate is varied it is in general difficult to invert\nthe experimental data unless the curvature at the top of the one dimensional\nfree energy profile is large, i.e the barrier is sharp. The independence of the\nTS location on force holds good only for brittle or hard biomolecules whereas\nthe TS location changes considerably if the molecule is soft or plastic. We\nalso comment on the usefulness of extension of the molecule as a surrogate\nreaction coordinate especially in the context of force-quench refolding of\nproteins and RNA.",
        "positive": "Spin dynamics of low-dimensional excitons due to acoustic phonons: We investigate the spin dynamics of excitons interacting with acoustic\nphonons in quantum wells, quantum wires and quantum disks by employing a\nmultiband model based on the $4\\times4$ Luttinger Hamiltonian. We also use the\nBir-Pikus Hamiltonian to model the coupling of excitons to both longitudinal\nacoustic phonons and transverse acoustic phonons, thereby providing us with a\nrealistic framework in which to determine details of the spin dynamics of\nexcitons. We use a fractional dimensional formulation to model the excitonic\nwavefunctions and we demonstrate explicitly the decrease of spin relaxation\ntime with dimensionality. Our numerical results are consistent with\nexperimental results of spin relaxation times for various configurations of the\nGaAs/Al$_{0.3}$Ga$_{0.7}$As material system. We find that longitudinal and\ntransverse acoustic phonons are equally significant in processes of exciton\nspin relaxations involving acoustic phonons."
    },
    {
        "anchor": "Nonequilibrium Glass Transition in Mixtures of Active-Passive Particles: We develop a mode coupling theory(MCT) to study the nonequilibrium glass\ntransition behavior of a mono-disperse mixture of active-passive hard-sphere\nparticles. The MCT equations clearly demonstrate that the glass transition is\nshifted to higher values of total volume fraction when doping a passive system\nwith active particles. Interestingly, we find that the glass transition point\nmay show a non-monotonic dependence on the effective diffusivity of the active\ncomponent, indicating a nontrivial type of activity induced reentrance\nbehavior. Analysis based on the nonergodic parameters suggest that the glassy\nstate at small activity is due to the caging effect, while that at high\nactivity could result from activity induced dynamic clustering.",
        "positive": "Director Deformations, Geometric Frustration, and Modulated Phases in\n  Liquid Crystals: This article analyzes modulated phases in liquid crystals, from the\nlong-established cholesteric and blue phases to the recently discovered\ntwist-bend, splay-bend, and splay nematic phases, as well as the\ntwist-grain-boundary (TGB) and helical nanofilament variations on smectic\nphases. The analysis uses the concept of four fundamental modes of director\ndeformation: twist, bend, splay, and a fourth mode related to saddle-splay.\nEach mode is coupled to a specific type of molecular order: chirality,\npolarization perpendicular and parallel to the director, and octupolar order.\nWhen the liquid crystal develops one type of spontaneous order, the ideal local\nstructure becomes nonuniform, with the corresponding director deformation. In\ngeneral, the ideal local structure is frustrated; it cannot fill space. As a\nresult, the liquid crystal must form a complex global phase, which may have a\ncombination of deformation modes, and may have a periodic array of defects.\nThus, the concept of an ideal local structure under geometric frustration\nprovides a unified framework to understand the wide variety of modulated\nphases."
    },
    {
        "anchor": "Fractal Dimension and Localization of DNA Knots: The scaling properties of DNA knots of different complexities were studied by\natomic force microscope. Following two different protocols DNA knots are\nadsorbed onto a mica surface in regimes of (i) strong binding, that induces a\nkinetic trapping of the three-dimensional (3D) configuration, and of (ii) weak\nbinding, that permits (partial) relaxation on the surface. In (i) the gyration\nradius of the adsorbed DNA knot scales with the 3D Flory exponent $\\nu\\approx\n0.58$ within error. In (ii), we find $\\nu\\approx 0.66$, a value between the 3D\nand 2D ($\\nu=3/4$) exponents, indicating an incomplete 2D relaxation or a\ndifferent polymer universality class. Compelling evidence is also presented for\nthe localization of the knot crossings in 2D.",
        "positive": "Entropic Cohesion in Vitrimers: Vitrimers are polymer networks that can undergo bond exchange reactions. They\ndynamically rearrange their structures while maintaining their overall\nintegrity, thus resulting in unique properties such as self-healing,\nreprocessability, shape memory and adaptability. Here, we show that the\nintroduction of dynamic bonds directly impacts the polymer density. For a\nlimiting case, where the dynamic bonds are the same size as the polymer chain\nbonds, simulations and theory show an enhancement in the density, because these\nbonds induce an increased cohesive force in the liquid, which is entropic in\norigin. The crosslinks are well mixed in the bulk but are depleted from the air\nand polymer interface. These findings implicate density as a key variable in\npolymers with dynamic crosslinkers, one that can be used to facilely tune their\nproperties."
    },
    {
        "anchor": "Control of drop positioning using chemical patterning: We explore how chemical patterning on surfaces can be used to control drop\nwetting. Both numerical and experimental results are presented to show how the\ndynamic pathway and equilibrium shape of the drops are altered by a hydrophobic\ngrid. The grid proves a successful way of confining drops and we show that it\ncan be used to alleviate {\\it mottle}, a degradation in image quality which\nresults from uneven drop coalescence due to randomness in the positions of the\ndrops within the jetted array.",
        "positive": "Analytical coupled vibroacoustic modeling of membrane-type acoustic\n  metamaterials: membrane model: Membrane-type Acoustic Metamaterials (MAMs) have demonstrated unusual\ncapacity in controlling low-frequency sound transmission/reflection. In this\npaper, an analytical vibroacoustic membrane model is developed to study sound\ntransmission behavior of the MAM under a normal incidence. The MAM is composed\nof a prestretched elastic membrane with attached rigid masses. To accurately\ncapture finite-dimension rigid mass effects on the membrane deformation, the\npoint matching approach is adopted by applying a set of distributed point\nforces along the interfacial boundary between masses and the membrane. The\naccuracy and capability of the theoretical model is verified through the\ncomparison with the finite element method. In particular, microstructure\neffects such as weight, size and eccentricity of the attached mass, pretension\nand thickness of the membrane on the resulting transmission peak and dip\nfrequencies of the MAM are quantitatively investigated. New peak and dip\nfrequencies are found for the MAM with one and multiple eccentric attached\nmasses. The developed model can be served as an efficient tool for design of\nsuch membrane-type metamaterials."
    },
    {
        "anchor": "Fingerprinting Soft Materials: A Framework for Characterizing Nonlinear\n  Viscoelasticity: We introduce a comprehensive scheme to physically quantify both viscous and\nelastic rheological nonlinearities simultaneously, using an imposed large\namplitude oscillatory shear (LAOS) strain. The new framework naturally lends a\nphysical interpretation to commonly reported Fourier coefficients of the\nnonlinear stress response. Additionally, we address the ambiguities inherent in\nthe standard definitions of viscoelastic moduli when extended into the\nnonlinear regime, and define new measures which reveal behavior that is\nobscured by conventional techniques.",
        "positive": "Effects of Asymmetric Cooling and Surface Wettability on the Orientation\n  of the Freezing Tip: Freezing of water droplets placed on the bare and superhydrophobic surfaces\nof polymer wedges are studied both experimentally and computationally.\nTwo-dimensional numerical calculations of the transient temperature field in a\nchilled polymer wedge show that the direction of heat flux from the droplet\nthrough the thermal contact region with the wedge differs significantly from\nthe normal to the wedge surface. This is the physical cause of the recently\nobserved asymmetric cooling of the droplet. A novel approximate computational\nmodel is proposed that takes into account the variable area of the water\nfreezing front in the droplet. This model gives a quantitative estimate of the\nfaster freezing of the droplet on the bare surface. The obtained numerical\nresults agree with the data of laboratory experiments. The velocity of the\ncrystallization front and the droplet deformation including the so-called\nfreezing tip formation are monitored in the experiment. The direction of the\nfreezing cone axis appears to be noticeably different for the cases of bare and\nsuperhydrophobic wedge surfaces. This deviation is explained by the fact that\nthe direction of the freezing cone axis is controlled by the local direction of\nthe heat flux. For a hydrophobic wedge surface, the deviation of the freezing\ntip from the vertical is smaller, because the reduced thermal contact area\nreduces the influence of the heat flux direction at the wedge surface."
    },
    {
        "anchor": "Anisotropic elastic theory of preloaded granular media: A macroscopic elastic description of stresses in static, preloaded granular\nmedia is derived systematically from the microscopic elasticity of individual\ninter-grain contacts. The assumed preloaded state and friction at contacts\nensure that the network of inter-grain contacts is not altered by small\nperturbations. The texture of this network, set by the preparation of the\nsystem, is encoded in second and fourth order fabric tensors. A small\nperturbation generates both normal and tangential inter-grain forces, the\nlatter causing grains to reorient. This reorientation response and the\nincremental stress are expressed in terms of the macroscopic strain.",
        "positive": "Polydispersity analysis of Taylor dispersion data: the cumulant method: Taylor dispersion analysis is an increasingly popular characterization method\nthat measures the diffusion coefficient, and hence the hydrodynamic radius, of\n(bio)polymers, nanoparticles or even small molecules. In this work, we describe\nan extension to current data analysis schemes that allows size polydispersity\nto be quantified for an arbitrary sample, thereby significantly enhancing the\npotentiality of Taylor dispersion analysis. The method is based on a cumulant\ndevelopment similar to that used for the analysis of dynamic light scattering\ndata. Specific challenges posed by the cumulant analysis of Taylor dispersion\ndata are discussed, and practical ways to address them are proposed. We\nsuccessfully test this new method by analyzing both simulated and experimental\ndata for solutions of moderately polydisperse polymers and polymer mixtures."
    },
    {
        "anchor": "Prediction of long and short time rheological behavior in soft glassy\n  materials: We present an effective time approach to predict long and short time\nrheological behavior of soft glassy materials from experiments carried out over\npractical time scales. Effective time approach takes advantage of relaxation\ntime dependence on aging time that allows time-aging time superposition even\nwhen aging occurs over the experimental timescales. Interestingly experiments\non variety of soft materials demonstrate that the effective time approach\nsuccessfully predicts superposition for diverse aging regimes ranging from\nsub-aging to hyper-aging behaviors. This approach can also be used to predict\nbehavior of any response function in molecular as well as spin glasses.",
        "positive": "Marangoni flow at droplet interfaces: Three-dimensional solution and\n  applications: The Marangoni effect refers to fluid flow induced by a gradient in surface\ntension at a fluid-fluid interface. We determine the full three-dimensional\nMarangoni flow generated by a non-uniform surface tension profile at the\ninterface of a self-propelled spherical emulsion droplet. For all flow fields\ninside, outside, and at the interface of the droplet, we give analytical\nformulas. We also calculate the droplet velocity vector $\\mathbf{v}^D$, which\ndescribes the swimming kinematics of the droplet, and generalize the squirmer\nparameter $\\beta$, which distinguishes between different swimmer types called\nneutral, pusher, or puller. In the second part of this paper, we present two\nillustrative examples, where the Marangoni effect is used in active emulsion\ndroplets. First, we demonstrate how micelle adsorption can spontaneously break\nthe isotropic symmetry of an initially surfactant-free emulsion droplet, which\nthen performs directed motion. Second, we think about light-switchable\nsurfactants and laser light to create a patch with a different surfactant type\nat the droplet interface. Depending on the setup such as the wavelength of the\nlaser light and the surfactant type in the outer bulk fluid, one can either\npush droplets along unstable trajectories or pull them along straight or\noscillatory trajectories regulated by specific parameters. We explore these\ncases for strongly absorbing and for transparent droplets."
    },
    {
        "anchor": "Non-linear elasticity, yielding and entropy in amorphous solids: The holographic duality has proven successful in linking seemingly unrelated\nproblems in physics.Recently, intriguing correspondences between the physics of\nsoft matter and gravity are emerging,including strong similarities between the\nrheology of amorphous solids, effective field theories for elasticity and the\nphysics of black holes. However, direct comparisons between theoretical\npredictions and experimental/simulation observations remain limited. Here, we\nstudy the effects of non-linear elasticity on the mechanical and thermodynamic\nproperties of amorphous materials responding to shear, using effective field\nand gravitational theories. The predicted correlations among the non-linear\nelastic exponent, the yielding strain/stress and the entropy change due to\nshear are supported qualitatively by simulations of granular matter models. Our\napproach opens a path towards understanding complex mechanical responses of\namorphous solids, such as mixed effects of shear softening and shear hardening,\nand offers the possibility to study the rheology of solid states and black\nholes in a unified framework.",
        "positive": "Self-consistent analisys of the contact phenomena in low-mobility\n  semiconductors: Self-consistent solution of charge injection and transport in low mobility\nLEDs is reported . We show that explicit description of the contact region\nunder the same premise as transport equation is needed to accurately evaluate\nthe current-voltage characteristics of polymer or small-molecule based LEDs .\nThe result is compared to widely used models, which treat the contact region in\nimplicit manner ."
    },
    {
        "anchor": "Fluctuation induced chiral symmetry breaking in autocatalytic\n  reaction-diffusion systems: We show how spatiotemporal fluctuations can induce spontaneous symmetry\nbreaking in systems which are perfectly symmetric in the absence of\nfluctuations. We illustrate this in the context of the autocatalytic production\nof chiral enantiomers from achiral reactants in reaction-diffusion systems. The\nmean field steady state is chiral symmetric; spatiotemporal fluctuations induce\na novel (molecular) chiral ordering and sharp phase transitions including\nreentrance. We discuss its implications in the context of the emergence of\nmolecular homochirality.",
        "positive": "User-friendly, theory-based web applet for rapidly predicting structure\n  and thermodynamics of complex fluids: Based on a recently introduced analytical strategy [Hollingshead et al., J.\nChem. Phys. 139, 161102 (2013)], we present a web applet that can quickly and\nsemi-quantitatively estimate the equilibrium radial distribution function and\nrelated thermodynamic properties of a fluid from knowledge of its pair\ninteraction. We present a detailed description of the applet's features and\nintended workflow, followed by a description of how the applet can be used to\nillustrate two (of many possible) concepts of interest for introductory\nstatistical mechanics courses: the transition from ideal gas-like behavior to\ncorrelated-liquid behavior with increasing density and the tradeoff between\ndominant length scales with changing temperature in a system with ramp-shaped\nrepulsions. The latter type of interaction qualitatively captures distinctive\nthermodynamic properties of liquid water because its energetic bias toward\nlocally open structures mimics that of water's hydrogen-bond network."
    },
    {
        "anchor": "Dynamical density functional theory for dense suspensions of colloidal\n  hard spheres: We study structural relaxation of colloidal hard spheres undergoing Brownian\nmotion using dynamical density functional theory. Contrary to the partial\nlinearization route [Stopper {\\em et al.}, Phys. Rev. E {\\bf 92}, 022151\n(2015)] which amounts to using different free energy functionals for the self\nand distinct part of the van Hove function $G(r,t)$, we put forward a unified\ndescription employing a single functional for both components. To this end,\ninteractions within the self part are removed via the zero-dimensional limit of\nthe functional with a quenched self component. In addition, we make use of a\ntheoretical result for the long-time mobility in hard-sphere suspensions, which\nwe adapt to the inhomogeneous fluid. Our results for $G(r,t)$ are in excellent\nagreement with numerical simulations even in the dense liquid phase. In\nparticular, our theory accurately yields the crossover from free diffusion at\nshort times to the slower long-time diffusion in a crowded environment.",
        "positive": "Bilayer elasticity at the nanoscale: the need for new terms: Continuum elastic models that account for membrane thickness variations are\nespecially useful in the description of nanoscale deformations due to the\npresence of membrane proteins with hydrophobic mismatch. We show that terms\ninvolving the gradient and the Laplacian of the area per lipid are significant\nand must be retained in the effective Hamiltonian of the membrane. We reanalyze\nrecent numerical data, as well as experimental data on gramicidin channels, in\nlight of our model. This analysis yields consistent results for the term\nstemming from the gradient of the area per molecule. The order of magnitude we\nfind for the associated amplitude, namely 13-60 mN/m, is in good agreement with\nthe 25 mN/m contribution of the interfacial tension between water and the\nhydrophobic part of the membrane. The presence of this term explains a\nsystematic variation in previously published numerical data."
    },
    {
        "anchor": "Bulk Metallic Glasses Deform via Slip Avalanches: Inelastic deformation of metallic glasses occurs via slip events with\navalanche dynamics similar to those of earthquakes. For the first time in these\nmaterials, measurements have been obtained with sufficiently high temporal\nresolution to extract both the exponents and the scaling functions that\ndescribe the nature, statistics and dynamics of the slips according to a simple\nmean-field model. These slips originate from localized deformation in shear\nbands. The mean-field model describes the slip process as an avalanche of\nrearrangements of atoms in shear transformation zones (STZs). Small slips show\nthe predicted power-law scaling and correspond to limited propagation of a\nshear front, while large slips are associated with uniform shear on\nunconstrained shear bands. The agreement between the model and data across\nmultiple independent measures of slip statistics and dynamics provides\ncompelling evidence for slip avalanches of STZs as the elementary mechanism of\ninhomogeneous deformation in metallic glasses.",
        "positive": "Forcing Adsorption of a Tethered Polymer by Pulling: We present an analysis of a partially directed walk model of a polymer which\nat one end is tethered to a sticky surface and at the other end is subjected to\na pulling force at fixed angle away from the point of tethering. Using the\nkernel method, we derive the full generating function for this model in two and\nthree dimensions and obtain the respective phase diagrams.\n  We observe adsorbed and desorbed phases with a thermodynamic phase transition\nin between. In the absence of a pulling force this model has a second-order\nthermal desorption transition which merely gets shifted by the presence of a\nlateral pulling force. On the other hand, if the pulling force contains a\nnon-zero vertical component this transition becomes first-order.\n  Strikingly, we find that if the angle between the pulling force and the\nsurface is beneath a critical value, a sufficiently strong force will induce\npolymer adsorption, no matter how large the temperature of the system.\n  Our findings are similar in two and three dimensions, an additional feature\nin three dimensions being the occurrence of a reentrance transition at constant\npulling force for small temperature, which has been observed previously for\nthis model in the presence of pure vertical pulling. Interestingly, the\nreentrance phenomenon vanishes under certain pulling angles, with details\ndepending on how the three-dimensional polymer is modeled."
    },
    {
        "anchor": "Predicting the orientation of adsorbed proteins steered with electric\n  fields using a simple electrostatic model: Under the most common experimental conditions, the adsorption of proteins to\nsolid surfaces is an spontaneous process that leads to a rather compact layer\nof randomly oriented molecules. Due to the importance of this process for the\ndevelopment of catalytic surfaces, a number of existing computational and\nexperimental approaches try to predict and control the orientation of such\nmolecules. However, and despite their own advantages, these tend to be either\ntoo expensive computationally, or oversimplified, undermining their ability to\npredict the most appropriate experimental conditions to maximize the catalytic\nactivity of adsorbed proteins. To address this current need, we present an\nefficient computational approach to model the behavior of proteins near\nsurfaces in the presence of an external electric field, based on continuum\nelectrostatics. Our model can not only estimate the overall affinity of the\nprotein with the surface, but also their most likely orientation as a function\nof the potential applied. In this way, a rational selection of the potential\ncan be performed to maximize the accessibility of the protein's active site to\nthe solvent. The model relies on the Poisson-Boltzmann equation and was\nimplemented in an extension of the code PyGBe that includes an external\nelectric field, and renders the electrostatic component of the solvation free\nenergy. To demonstrate the feasibility of this technique, we investigate the\nadsorption of trypsin onto a carbon electrode under potentiostatic conditions\nboth numerically and experimentally. We found that even though the adsorption\nprocess is largely dominated by hydrophobic effects, the orientation of trypsin\ncan be controlled through an external potential, influencing the position of\nthe active sites, and resulting in an important change in the catalytic\nactivity of the surface.",
        "positive": "Role of transverse excitations in the instability of Bose-Einstein\n  condensates moving in optical lattices: The occurrence of energetic and dynamical instabilities in a Bose-Einstein\ncondensate moving in a one-dimensional (1D) optical lattice is analyzed by\nmeans of the Gross-Pitaevskii theory. Results of full 3D calculations are\ncompared with those of an effective 1D model, the nonpolynomial Schrodinger\nequation, pointing out the role played by transverse degrees of freedom. The\ninstability thresholds are shown to be scarcely affected by transverse\nexcitations, so that they can be accurately predicted by effective 1D models.\nConversely, transverse excitations turn out to be important in characterizing\nthe stability diagram and the occurrence of a complex radial dynamics above the\nthreshold for dynamical instability. This analysis provides a realistic\nframework to discuss the dissipative dynamics observed in recent experiments."
    },
    {
        "anchor": "The role of interfacial adhesion on minimum wear particle size and\n  roughness evolution: Adhesion between two bodies is a key parameter in wear processes. At the\nmacroscale, strong adhesive bonds are known to lead to high wear rates, as\nobserved in clean metal-on-metal contact. Reducing the strength of the\ninterfacial adhesion is then desirable, and techniques such as lubrication and\nsurface passivation are employed to this end. Still, little is known about the\ninfluence of adhesion on the microscopic processes of wear. In particular, the\neffects of interfacial adhesion on the wear particle size and on the surface\nroughness evolution are not clear, and are therefore addressed here by means of\nmolecular dynamics simulations. We show that, at short timescales, the surface\nmorphology and not the interfacial adhesion strength dictates the minimum size\nof wear particles. However, at longer timescales, adhesion alters the particle\nmotion and thus the wear rate and the surface morphology.",
        "positive": "Hole interactions with molecular vibrations on DNA: We report on a study of the interactions between holes and molecular\nvibrations on dry DNA using photoinduced infrared absorption spectroscopy.\nLaser photoexcited (PE) holes are found to have a room-temperature lifetime in\nexcess of 1 ms, clearly indicating the presence of localization. However, from\na quantitative model analysis of the frequency shifts of vibrational modes\ncaused by the PE holes, we find the holevibrational coupling constant to be\nrelatively small, 0.2. This interaction leads to a change in the conformational\nenergy of 0.015 eV, which is too small to cause selftrapping at room\ntemperature. We conclude that, at least in the dry (A) form, DNA is best\nunderstood in terms of a double chain of coupled quantum dots arising from the\npseudo-random chain sequence of base pairs, in which Anderson localization\nprevents the formation of a metallic state."
    },
    {
        "anchor": "Inhibition of DNA ejection from bacteriophage by Mg+2 counterions: The problem of inhibiting viral DNA ejection from bacteriophages by\nmultivalent counterions, specifically Mg$^{+2}$ counterions, is studied.\nExperimentally, it is known that MgSO$_4$ salt has a strong and non-monotonic\neffect on the amount of DNA ejected. There exists an optimal concentration at\nwhich the minimum amount of DNA is ejected from the virus. At lower or higher\nconcentrations, more DNA is ejected from the capsid. We propose that this\nphenomenon is the result of DNA overcharging by Mg$^{+2}$ multivalent\ncounterions. As Mg$^{+2}$ concentration increases from zero, the net charge of\nDNA changes from negative to positive. The optimal inhibition corresponds to\nthe Mg$^{+2}$ concentration where DNA is neutral. At lower/higher\nconcentrations, DNA genome is charged. It prefers to be in solution to lower\nits electrostatic self-energy, which consequently leads to an increase in DNA\nejection. By fitting our theory to available experimental data, the strength of\nDNA$-$DNA short range attraction energies, mediated by Mg$^{+2}$, is found to\nbe $-$0.004 $k_BT$ per nucleotide base. This and other fitted parameters agree\nwell with known values from other experiments and computer simulations. The\nparameters are also in aggreement qualitatively with values for tri- and\ntetra-valent counterions.",
        "positive": "Hourglass pore effect and membrane osmotic diode behavior: model and\n  simulations: A membrane can be represented by an energy landscape that solutes or colloids\nmust cross. A model accounting for the momentum and the mass balances on the\nmembrane energy landscape establishes a new way of writing for the Darcy law.\nThe counter pressure in the Darcy law is no longer written as the result of an\nosmotic pressure difference but rather as a function of colloid-membrane\ninteractions. Physically, the colloid-membrane interactions are slowing down\nthe colloid velocity thus inducing a relative fluid-colloid motion that in turn\nleads to the counter pressure. The ability of the model to describe the physics\nof the filtration is discussed in detail. This model is solved on a simplified\nenergy landscape to derive analytical relationships that describe the\nselectivity and the counter pressure from ab-initio operating conditions. The\nmodel shows that the stiffness of the energy landscape has an impact on the\nprocess efficiency: a gradual increase in interactions (like with hourglass\npore shape) can reduce the separation energetic cost. It allows the\nintroduction of a new paradigm to increase membrane efficiency: the\naccumulation that is inherent to the separation must be distributed across the\nmembrane."
    },
    {
        "anchor": "Comparative study of anomalous size dependence of charged and neutral\n  solute diffusion in water: In this work, we perform a comparative study of the size dependence of\ndiffusion of charged and neutral solutes in water. The neutral solute in water\nshows a nonmonotonicity in the size dependence of diffusion. This is usually\nconnected to the well known Levitation effect where it is found that when\nsolute diffuses through the transient solvent cages then for attractive\nsolute-solvent interaction and for a particular size of the solute there is a\nforce balance which leads to the maximum in diffusion. Similar maximum in\ndiffusion of charged solutes has also been observed and connected to Levitation\neffect. However, earlier studies of ionic diffusion connects this\nnonmonotonicity to the interplay between hard sphere repulsion and Coulombic\nattraction. In this work, we show that although the size dependence of both\ncharged and neutral solutes have a nonmonotonicity, there is a stark difference\nin their behaviour. For charged solute with increase in attraction the maximum\nshifts to higher solute sizes and has a lower value whereas for neutral solute\nit remains at the same place and has a higher value. We show by studying the\nionic and non-ionic part of the potential that for larger solutes it is the\nnonionic part which dominates and for smaller solutes the ionic part and the is\na transition between them. As the charge on the solute increases, this\ntransition takes place at larger solute sizes which leads to the shift in the\ndiffusivity maxima and reduction of the peak value. We show that although the\ncharged solutes also explore the solvent cage even before we reach the size\nwhich Levitates due to Coulombic attraction the diffusion value drops. Thus the\norigin of diffusivity maxima in charged and neutral solute diffusion is\ndifferent.",
        "positive": "Propulsion and energetics of a minimal magnetic microswimmer: In this manuscript we describe the realization of a minimal hybrid\nmicroswimmer, composed of a ferromagnetic nanorod and a paramagnetic\nmicrosphere. The unbounded pair is propelled in water upon application of a\nswinging magnetic field that induces a periodic relative movement of the two\ncomposing elements, where the nanorod rotates and slides on the surface of the\nparamagnetic sphere. When taken together, the processes of rotation and sliding\ndescribe a finite area in the parameter space, which increases with the\nfrequency of the applied field. We develop a theoretical approach and combine\nit with numerical simulations, which allow us to understand the dynamics of the\npropeller and explain the experimental observations. Furthermore, we\ndemonstrate a reversal of the microswimmer velocity by varying the length of\nthe nanorod, as predicted by the model. Finally, we determine theoretically and\nin experiments the Lighthill's energetic efficiency of this minimal magnetic\nmicroswimmer."
    },
    {
        "anchor": "Rubber adhesion and friction: role of surface energy and contamination\n  films: We study the influence of the surface energy and contamination films on\nrubber adhesion and sliding friction. We find that there is a transfer of\nmolecules from the rubber to the substrate which reduces the work of adhesion\nand makes the rubber friction insensitive to the substrate surface energy. We\nshow that there is no simple relation between adhesion and friction: adhesion\nis due to (vertical) detachment processes at the edge of the contact regions\n(opening crack propagation), while friction in many cases is determined mainly\nby (tangential) stick-slip instabilities of nanosized regions, within the whole\nsliding contact. Thus while the pull-off force in fluids may be strongly\nreduced (due to a reduction of the work of adhesion), the sliding friction may\nbe only slightly affected as the area of real contact may be dry, and the\nfrictional shear stress in the contact area nearly unaffected by the fluid.",
        "positive": "Equivalent variational approaches to biaxial liquid crystal dynamics: Within the framework of liquid crystal flows, the Qian & Sheng (QS) model for\nQ-tensor dynamics is compared to the Volovik & Kats (VK) theory of biaxial\nnematics by using Hamilton's variational principle. Under the assumption of\nrotational dynamics for the Q-tensor, the variational principles underling the\ntwo theories are equivalent and the conservative VK theory emerges as a\nspecialization of the QS model. Also, after presenting a micropolar variant of\nthe VK model, Rayleigh dissipation is included in the treatment. Finally, the\ntreatment is extended to account for nontrivial eigenvalue dynamics in the VK\nmodel and this is done by considering the effect of scaling factors in the\nevolution of the Q-tensor."
    },
    {
        "anchor": "Shear-induced contact area anisotropy explained by a fracture mechanics\n  model: This paper gives a theoretical analysis for the fundamental problem of\nanisotropy induced by shear forces onan adhesive contact, discussing the\nexperimental data of the companion Letter. We present a fracture mechanicsmodel\nwhere two phenomenological mode-mixity functions are introduced to describe the\nweak couplingbetween modes I and II or I and III, which changes the effective\ntoughness of the interface. The mode-mixityfunctions have been interpolated\nusing the data of a single experiment and then used to predict the behavior of\nthewhole set of experimental observations. The model extends an idea by Johnson\nand Greenwood, to solve purelymode I problems of adhesion in the presence of a\nnonaxisymmetric Hertzian geometry, to the case of ellipticalcontacts sheared\nalong their major or minor axis. Equality between the stress intensity factors\nand their criticalvalues is imposed solely at the major and minor axes. We\nsuccessfully validate our model against experimentaldata. The model predicts\nthat the punch geometry will affect both the shape and the overall decay of the\nshearedcontact area.",
        "positive": "Absolute vs Convective Instabilities and Front Propagation in Lipid\n  Membrane Tubes: We analyze the stability of biological membrane tubes, with and without a\nbase flow of lipids. Membrane dynamics are completely specified by two\ndimensionless numbers: the well-known F\\\"oppl--von K\\'arm\\'an number $\\Gamma$\nand the recently introduced Scriven--Love number $SL$, respectively quantifying\nthe base tension and base flow speed. For unstable tubes, the growth rate of a\nlocal perturbation depends only on $\\Gamma$, whereas $SL$ governs the absolute\nor convective nature of the instability. Furthermore, nonlinear simulations of\nunstable tubes reveal an initially localized disturbance results in propagating\nfronts, which leave a thin atrophied tube in their wake. Depending on the value\nof $\\Gamma$, the thin tube is connected to the unperturbed regions via\noscillatory or monotonic shape transitions -- reminiscent of recent\nexperimental observations on the retraction and atrophy of axons. We elucidate\nour findings through a weakly nonlinear analysis, which shows membrane dynamics\nmay be approximated by a model of the class of extended Fisher--Kolmogorov\nequations. Our study sheds light on the pattern selection mechanism in axonal\nshapes by recognizing the existence of two Lifshitz points, at which the front\ndynamics undergo steady-to-oscillatory bifurcations."
    },
    {
        "anchor": "Close to the edge of Fundamental Measure Theory: density functional for\n  hard sphere mixtures: We analyze the structure of the Fundamental Measure Theory for the free\nenergy density functional of hard sphere mixtures. A comparative study of the\ndifferent versions of the theory, and other density functional approaches, is\ndone in terms of their generic form for the three-points direct correlation\nfunction, which shows clearly the main advantages and problems of the different\napproximations. A recently developed version for the monocomponent case is\nextended to mixtures of hard spheres with different radii, and a new\nprescription is presented to obtain the exact dimensional crossover of those\nmixtures in the one-dimensional (1D) limit. Numerical results for planar\nwall-fluid interfaces and for the 1D fluid are presented.",
        "positive": "Surface profiles with zero and finite adhesion force and adhesion\n  instabilities: A simple but general analysis of stability of axis-symmetric adhesive\ncontacts is provided. Adhesion is considered in the JKR-approximation.\nDepending on the shape of the contacting bodies, various scenarios are\npossible, including vanishing adhesive force, complete contact as well as\ntransitions between these states."
    },
    {
        "anchor": "Implications of SU(2) symmetry on the dynamics of population difference\n  in the two-component atomic vapor: We present an exact many body solution for the dynamics of the population\ndifference $N_2-N_1$ induced by an rf-field in the two-component atomic cloud\ncharacterized by equal scattering lengths. This situation is very close to the\nactual JILA experiments with the two-component $^{87}$Rb vapor. We show that no\nintrinsic decoherence exists for $N_2-N_1$, provided the exact SU(2) symmetry\nholds. This contrasts with finite dissipation of the normal modes even in the\npresence of the SU(2) symmetry. The intrinsic decoherence for \\$N_2-N_1$ may\noccur as long as deviations from the exact SU(2) symmetry are taken into\naccount. Such decoherence, however, should be characterized by very long times\ngoverned by the smallness of the deviations from the symmetry. We suggest\ntesting the evolution of $N_2-N_1$ by conducting echo-type experiments.",
        "positive": "A fundamental-measure density functional for mixtures of parallel hard\n  cylinders: We obtain a fundamental measure density functional for mixtures of parallel\nhard cylinders. To this purpose we first generalize to multicomponent mixtures\nthe fundamental measure functional proposed by Tarazona and Rosenfeld for a\none-component hard disk fluid, through a method alternative to the cavity\nformalism of these authors. We show the equivalence of both methods when\napplied to two-dimensional fluids. The density functional so obtained reduces\nto the exact density functional for one-dimensional mixtures of hard rods when\napplied to one-dimensional profiles. In a second step we apply an idea put\nforward some time ago by two of us, based again on a dimensional reduction of\nthe system, and derive a density functional for mixtures of parallel hard\ncylinders. We explore some features of this functional by determining the\nfluid-fluid demixing spinodals for a binary mixture of cylinders with the same\nvolume, and by calculating the direct correlation functions."
    },
    {
        "anchor": "Cluster Glass Transition of Ultrasoft-Potential Fluids at High Density: Using molecular dynamics simulation, we investigate the slow dynamics of a\nsupercooled binary mixture of soft particles interacting with a generalized\nHertzian potential. At low density, it displays typical slow dynamics near its\nglass transition temperature. At higher densities, particles bond together,\nforming clusters, and the clusters undergo the glass transition. The number of\nparticles in a cluster increases one by one as the density increases. We\ndemonstrate that there exist the multiple cluster-glass phases characterized by\na different number of particles per cluster, each of which is separated by\ndistinct minima. Surprisingly, a so-called higher order singularity of the\nmode-coupling theory signaled by a logarithmic relaxation is observed in the\nvicinity of the boundaries between monomer and cluster glass phases. The system\nalso exhibits rich and anomalous dynamics in the cluster glass phases, such as\nthe decoupling of the self- and collective dynamics.",
        "positive": "Scaling transition of active turbulence from two to three dimensions: Turbulent flows are observed in low-Reynolds active fluids. They are\nintrinsically different from the classical inertial turbulence and behave\ndistinctively in two- and three-dimensions. Understanding the behaviors of this\nnew type of turbulence and their dependence on the system dimensionality is a\nfundamental challenge in non-equilibrium physics. We experimentally measure\nflow structures and energy spectra of bacterial turbulence between two large\nparallel plates spaced by different heights $H$. The turbulence exhibits three\nregimes as H increases, resulting from the competition of bacterial length,\nvortex size and H. This is marked by two critical heights ($H_0$ and $H_1$) and\na $H^{0.5}$ scaling law of vortex size in the large-$H$ limit. Meanwhile, the\nspectra display distinct universal scaling laws in quasi-two-dimensional (2D)\nand three-dimensional (3D) regimes, independent of bacterial activity, length\nand $H$, whereas scaling exponents exhibit transitions in the crossover. To\nunderstand the scaling laws, we develop a hydrodynamic model using image\nsystems to represent the effect of no-slip confining boundaries. This model\npredicts universal 1 and -4 scaling on large and small length scales,\nrespectively, and -2 and -1 on intermediate length scales in 2D and 3D,\nrespectively, which are consistent with the experimental results. Our study\nsuggests a framework for investigating the effect of dimensionality on\nnon-equilibrium self-organized systems."
    },
    {
        "anchor": "Hidden force floating ice: Because of the segmental specific-heat disparity of the hydrogen bond (O:H-O)\nand the Coulomb repulsion between oxygen ions, cooling elongates the O:H-O bond\nat freezing by stretching its containing angle and shortening the H-O bond with\nan association of larger O:H elongation, which makes ice less dense than water,\nallowing it to float.",
        "positive": "Interpretation of Diffusing Wave Spectra in Nontrivial Systems: Mathematical methods previously used (Phillies, J. Chem. Phys., 122 224905\n(2005)) to interpret quasielastic light scattering spectroscopy (QELSS) spectra\nare here applied to relate diffusing wave spectroscopy (DWS) spectra to the\nmoments \\bar{X^{2n}} of particle displacements in the solution under study. DWS\nspectra of optical probes are like QELSS spectra in that in general they are\nnot determined solely by the second moment \\bar{X^{2}}. In each case, the\nrelationship between the spectrum and the particle motions arises from the\nfield correlation function g^{(1)}_{s}(t) for a single quasi-elastic scattering\nevent. In most physically interesting cases, g^{(1)}_{s}(t) receives except at\nthe shortest times large contributions from higher moments \\bar{X(t)^{2n}}, n\n>1. As has long been known, the idealized form g^{(1)}_{s}(t) =\\exp(-2 q^{2}\n\\bar{X(t)^{2}}), sometimes invoked to interpret DWS and QELSS spectra, only\nrefers to (adequately) monodisperse, noninteracting, probes in purely Newtonian\nliquids and is erroneous for polydisperse particles, interacting particles, or\nparticles in viscoelastic complex fluids. Furthermore, in DWS experiments\nfluctuations (for multiple scattering paths of fixed length) in the number of\nscattering events and the total-square scattering vector significantly modify\nthe spectrum."
    },
    {
        "anchor": "Influence of Controlled Viscous Dissipation on the Propagation of\n  Strongly Nonlinear Waves in Stainless Steel Based Phononic Crystals: Strongly nonlinear phononic crystals were assembled from stainless steel\nspheres. Single solitary waves and splitting of an initial pulse into a train\nof solitary waves were investigated in different viscous media using motor oil\nand non-aqueous glycerol to introduce a controlled viscous dissipation.\nExperimental results indicate that the presence of a viscous fluid dramatically\naltered the splitting of the initial pulse into a train of solitary waves.\nNumerical simulations qualitatively describe the observed phenomena only when a\ndissipative term based on the relative velocity between particles is\nintroduced.",
        "positive": "Electronic properties of guanine-based nanowires: We present a first-principle study of the electronic and conduction\nproperties of a few classes of nanowires constituted of guanine (G) molecules,\nself-assembled in different geometries. We first analyze the effect of the\nvertical $\\pi$-$\\pi$ interaction in model G-stack columns. Then, we exploit the\nresults obtained from those models to interpret the features of realistic\nstacked and hydrogen-bonded structures, namely the guanine quadruple helices\nand the planar ribbons. With respect to natural DNA, the different structures\nas well as the inclusion of metal cations, drastically affect the bonding\npattern among the bases, introducing novel features in the electronic\nproperties of the systems. These supramolecular G-aggregates, alternative to\nDNA, are expected to show intersting properties for molecular elec tronics\napplications."
    },
    {
        "anchor": "Quantum capacitance governs electrolyte conductivity in carbon nanotubes: In recent experiments, unprecedentedly large values for the conductivity of\nelectrolytes through carbon nanotubes (CNTs) have been measured, possibly owing\nto flow slip and a high pore surface charge density whose origin is still\nunknown. By accounting for the coupling between the {quantum} CNT and the\n{classical} electrolyte-filled pore capacitances, we study the case where a\ngate voltage is applied to the CNT. The computed surface charge and\nconductivity dependence on reservoir salt concentration and gate voltage are\nintimately connected to the CNT electronic density of states. This approach\nprovides key insight into why metallic CNTs have larger conductivities than\nsemi-conducting ones.",
        "positive": "Interplay between a hydrodynamic instability and a phase transition: the\n  Faraday instability in dispersions of rodlike colloids: Strong effects of the Faraday instability on suspensions of rodlike colloidal\nparticles are reported through measurements of the critical acceleration and of\nthe surface wave amplitude. We show that the transition to parametrically\nexcited surface waves displays discontinuous and hysteretic features. This\nsubcritical behaviour is attributed to the shear-thinning properties of our\ncolloidal suspensions thanks to a phenomenological model based on rheological\ndata under large amplitude oscillatory shear. Birefringence measurements\nprovide direct evidence that Faraday waves induce local nematic ordering of the\nrodlike colloids. While local alignment simply follows the surface oscillations\nfor dilute, isotropic suspensions, permanent nematic patches are generated by\nsurface waves in samples close to the isotropic-to-nematic transition and above\nthe transition large domains align in the flow direction. This strong coupling\nbetween the fluid microstructure and a hydrodynamic instability is confirmed by\nnumerical computations based on the microstructural response of rodlike viruses\nin shear flow."
    },
    {
        "anchor": "Sorting and separation of microparticles by surface properties using\n  liquid crystal-enabled electro-osmosis: Sorting and separation of microparticles is a challenging problem of\ninterdisciplinary nature. Existing technologies can differentiate\nmicroparticles by their bulk properties, such as size, density, electric\npolarizability, etc. The next level of challenge is to separate particles that\nshow identical bulk properties and differ only in subtle surface features, such\nas functionalization with ligands. In this work, we propose a technique to sort\nand separate particles and fluid droplets that differ in surface properties. As\na dispersive medium, we use a nematic liquid crystal (LC) rather than an\nisotropic fluid, which allows us to amplify the difference in surface\nproperties through distinct perturbations of LC order around the dispersed\nparticles. The particles are placed in a LC cell with spatially distorted\nmolecular orientation subject to an alternating current electric field. The\ngradients of the molecular orientation perform two functions. First, elastic\ninteractions between these pre-imposed gradients and distortions around the\nparticles separate the particles with different surface properties in space.\nSecond, these pre-imposed patterns create electro-osmotic flows powered by the\nelectric field that transport the sorted particles to different locations thus\nseparating them. The demonstrated unique sorting and separation capability\nopens opportunities in lab-on-a-chip, cell sorting and bio-sensing\napplications.",
        "positive": "Interplay of packing and flip-flop in local bilayer deformation. How\n  phosphatidylglycerol could rescue mitochondrial function in a\n  cardiolipin-deficient yeast mutant: In a previous work, we have shown that a spatially localized transmembrane pH\ngradient, produced by acid micro-injection near the external side of\ncardiolipin-containing giant unilamellar vesicles, leads to the formation of\ntubules that retract after the dissipation of this gradient. These tubules have\nmorphologies similar to mitochondrial cristae. The tubulation effect is due to\ndirect phospholipid packing modification in the outer leaflet that is promoted\nby protonation of cardiolipin headgroups. Here we compare the case of\ncardiolipin-containing giant unilamellar vesicles with that of\nphosphatidylglycerol-containing giant unilamellar vesicles. Local acidification\nalso promotes formation of tubules in the latter. However, compared to\ncardiolipin-containing giant unilamellar vesicles the tubules are longer,\nexhibit a visible pearling and have a much longer lifetime after acid\nmicro-injection is stopped. We attribute these differences to an additional\nmechanism that increases monolayer surface imbalance, namely inward PG\nflip-flop promoted by the local transmembrane pH-gradient. Simulations using a\nfully non-linear membrane model as well as geometrical calculations are in\nagreement with this hypothesis. Interestingly, among yeast mutants deficient in\ncardiolipin biosynthesis, only the crd1-null mutant, which accumulates\nphosphatidylglycerol, displays significant mitochondrial activity. Our work\nprovides a possible explanation of such a property and further emphasizes the\nsalient role of specific lipids in mitochondrial function."
    },
    {
        "anchor": "Hydrodynamic Stability Criterion for Colloidal Gelation under Gravity: Attractive colloids diffuse and aggregate to form gels, solid-like particle\nnetworks suspended in a fluid. Gravity is known to strongly impact the\nstability of gels once they are formed. However, its effect on the process of\ngel formation has seldom been studied. Here, we simulate the effect of gravity\non gelation using both Brownian dynamics and a lattice-Boltzmann algorithm that\naccounts for hydrodynamic interactions. We work in a confined geometry to\ncapture macroscopic, buoyancy-induced flows driven by the density mismatch\nbetween fluid and colloids. These flows give rise to a stability criterion for\nnetwork formation, based on an effective accelerated sedimentation of nascent\nclusters at low volume fractions that disrupts gelation. Above a critical\nvolume fraction, mechanical strength in the forming gel network dominates the\ndynamics: the interface between the colloid-rich and colloid-poor region moves\ndownward at an ever decreasing rate. Finally, we analyze the asymptotic state,\nthe colloidal gel-like sediment, which we find not to be appreciably impacted\nby the vigorous flows that can occur during the settling of the colloids. Our\nfindings represent the first steps toward understanding how flow during\nformation affects the life span of colloidal gels.",
        "positive": "Microswimming in viscoelastic fluids: The locomotion of microorganisms and spermatozoa in complex viscoelastic\nfluids is of critical importance in many biological processes such as\nfertilization, infection, and biofilm formation. Depending on their propulsion\nmechanisms, microswimmers display various responses to a complex fluid\nenvironment: increasing or decreasing their swimming speed and efficiency,\nmodifying their propulsion kinematics and swimming gaits, and experiencing\ndifferent hydrodynamic interactions with their surroundings. In this article,\nwe review the fundamental physics of locomotion of biological and synthetic\nmicroswimmers in complex viscoelastic fluids. Starting from a continuum\nframework, we describe the main theoretical approaches developed to model\nmicroswimming in viscoelastic fluids, which typically rely on asymptotically\nsmall dimensionless parameters. We then summarise recent progress on the\nmobility of single cells propelled by cilia, waving flagella and rotating\nhelical flagella in unbounded viscoelastic fluids. We next briefly discuss the\nimpact of other physical factors, including the micro-scale heterogeneity of\ncomplex biological fluids, the role of Brownian fluctuations of the\nmicroswimmers, the effect of polymer entanglement and the influence of\nshear-thinning viscosity. In particular, for solutions of long polymer chains\nwhose sizes are comparable to the radius of flagella, continuum models cannot\nbe used and instead Brownian Dynamics for the polymers can predict the swimming\ndynamics. Finally, we discuss the effect of viscoelasticity on the dynamics of\nmicroswimmers in the presence of surfaces or external flows and its impact on\ncollective cellular behavior."
    },
    {
        "anchor": "The one-loop elastic coefficients for the Helfrich membrane in higher\n  dimensions: Using a covariant geometric approach we obtain the effective bending\ncouplings for a 2-dimensional rigid membrane embedded into a\n$(2+D)$-dimensional Euclidean space. The Hamiltonian for the membrane has three\nterms: The first one is quadratic in its mean extrinsic curvature. The second\none is proportional to its Gaussian curvature, and the last one is proportional\nto its area. The results we obtain are in agreement with those finding that\nthermal fluctuations soften the 2-dimensional membrane embedded into a\n3-dimensional Euclidean space.",
        "positive": "Interplay of vitrification and ice formation in a cryoprotectant aqueous\n  solution at low temperature: The proneness of water to crystallize is a major obstacle to understanding\nits putative exotic behavior in the supercooled state. It also represents a\nstrong practical limitation to cryopreservation of biological systems. Adding\nsome concentration of glycerol, which has a cryoprotective effect preventing to\nsome degree water crystallization, has been proposed as a possible way out,\nprovided the concentration is small enough for water to retain some of its bulk\ncharacter and/or for limiting the damage caused by glycerol on living\norganisms. Contrary to previous expectations, we show that in the ``marginal''\nglycerol molar concentration $\\approx18\\%$, at which vitrification is possible\nwith no crystallization on rapid cooling, water crystallizes upon isothermal\nannealing even below the calorimetric glass transition of the solution. Through\na time-resolved polarized neutron scattering investigation, we extract key\nparameters, size and shape of the ice crystallites, fraction of water that\ncrystallizes, crystallization time, which are important for cryoprotection, as\na function of the annealing temperature. We also characterize the nature of the\nout-of-equilibrium liquid phases that are present at low temperature, providing\nmore arguments against the presence of an iso-compositional liquid-liquid\ntransition. Finally, we propose a rule-of-thumb to estimate the lower\ntemperature limit below which water crystallization does not occur in aqueous\nsolutions."
    },
    {
        "anchor": "Ion size effects at ionic exclusion from dielectric interfaces and slit\n  nanopores: A previously developed field-theoretic model [R.D. Coalson et al., J. Chem.\nPhys. 102, 4584 (1995)] that treats core collisions and Coulomb interactions on\nthe same footing is investigated in order to understand ion size effects on the\npartition of neutral and charged particles at planar interfaces and the ionic\nselectivity of slit nanopores. We introduce a variational scheme that can go\nbeyond the mean-field (MF) regime and couple in a consistent way pore modified\ncore interactions, steric effects, electrostatic solvation and image-charge\nforces, and surface charge induced electrostatic potential. We show that in the\ndilute limit, the MF and the variational theories agree well with MC simulation\nresults, in contrast to a recent RPA method. The partition of charged Yukawa\nparticles at a neutral dielectric interface (e.g air-water or protein-water\ninterface) is investigated. It is shown that as a result of the competition\nbetween core collisions that push the ions towards the surface, and repulsive\nsolvation and image forces that exclude them from the interface, a\nconcentration peak of finite size ions sets in close to the dielectric\ninterface. We also characterize the role played by the ion size on the ionic\nselectivity of neutral slit nanopores. We show that the complex interplay\nbetween electrostatic forces, excluded volume effects induced by core\ncollisions and steric effects leads to an unexpected reversal in the ionic\nselectivity of the pore with varying pore size: while large pores exhibits a\nhigher conductivity for large ions, narrow pores exclude large ions more\nefficiently than small ones.",
        "positive": "Statistical Mechanics of Splay Flexoelectricity in Nematic Liquid\n  Crystals: We develop a lattice model for the splay flexoelectric effect in nematic\nliquid crystals. In this model, each lattice site has a spin representing the\nlocal molecular orientation, and the interaction between neighboring spins\nrepresents pear-shaped molecules with shape polarity. We perform Monte Carlo\nsimulations and mean-field calculations to find the behavior as a function of\ninteraction parameters, temperature, and applied electric field. The resulting\nphase diagram has three phases: isotropic, nematic, and polar. In the nematic\nphase, there is a large splay flexoelectric effect, which diverges as the\nsystem approaches the transition to the polar phase. These results show that\nflexoelectricity is a statistical phenomenon associated with the onset of polar\norder."
    },
    {
        "anchor": "Competition of mixing and segregation in rotating cylinders: Using discrete element methods, we study numerically the dynamics of the size\nsegregation process of binary particle mixtures in three-dimensional rotating\ndrums, operated in the continuous flow regime. Particle rotations are included\nand we focus on different volume filling fractions of the drum to study the\ninterplay between the competing phenomena of mixing and segregation. It is\nfound that segregation is best for a more than half-filled drum due to the\nnon-zero width of the fluidized layer. For different particle size ratios, it\nis found that radial segregation occurs for any arbitrary small particle size\ndifference and the final amount of segregation shows a linear dependence on the\nsize ratio of the two particle species. To quantify the interplay between\nsegregation and mixing, we investigate the dynamics of the center of mass\npositions for each particle component. Starting with initially separated\nparticle groups we find that no mixing of the component is necessary in order\nto obtain a radially segregated core.",
        "positive": "Economical routes to size-specific assembly of self-closing structures: Self-assembly is one of the prevalent strategies used by living systems to\nfabricate ensembles of precision nanometer-scale structures and devices. The\npush for analogous approaches to create synthetic nanomaterials has led to the\ndevelopment of a large class of programmable crystalline structures. However,\nmany applications require `self-limiting' assemblies, which autonomously\nterminate growth at a well-defined size and geometry. For example, curved\narchitectures such as tubules, vesicles, or capsids can be designed to\nself-close at a particular size, symmetry, and topology. But developing\nsynthetic strategies for self-closing assembly has been challenging, in part\nbecause such structures are prone to polymorphism that arises from thermal\nfluctuations of their local curvature, a problem that worsens with increased\ntarget size. Here we demonstrate a strategy to eliminate this source of\npolymorphism in self-closing assembly of tubules by increasing the assembly\ncomplexity. In the limit of single-component assembly, we find that thermal\nfluctuations allow the system to assemble nearby, off-target structures with\nvarying widths, helicities, and chirality. By increasing the number of distinct\ncomponents, we reduce the density of off-target states, thereby increasing the\nselectivity of a user-specified target structure to nearly 100%. We further\nshow that by reducing the design constraints by targeting either the pitch or\nthe width of tubules, fewer components are needed to reach complete\nselectivity. Combining experiments with theory, our results reveal an\neconomical limit, which determines the minimum number of components that are\nrequired to create arbitrary assembly sizes with full selectivity. In the\nfuture, this approach could be extended to more complex self-limited\nstructures, such as shells or triply periodic surfaces."
    },
    {
        "anchor": "Deriving Finite Sphere Packings: Sphere packing problems have a rich history in both mathematics and physics;\nyet, relatively few analytical analyses of sphere packings exist, and answers\nto seemingly simple questions are unknown. Here, we present an analytical\nmethod for deriving all packings of n spheres in R^3 satisfying minimal\nrigidity constraints (>= 3 contacts per sphere and >= 3n-6 total contacts). We\nderive such packings for n <= 10, and provide a preliminary set of maximal\ncontact packings for 10 < n <= 20. The resultant set of packings has some\nstriking features, among them: (i) all minimally rigid packings for n <= 9 have\n3n-6 contacts, (ii) non-rigid packings satisfying minimal rigidity constraints\narise for n >= 9, (iii) the number of ground states (i.e. packings with the\nmaximal number of contacts) oscillates with respect to n, (iv) for 10 <= n <=\n20 there are only a small number of packings with the maximal number of\ncontacts, and for 10 <= n < 13 these are all commensurate with the HCP lattice.\nThe general method presented here may have applications to other related\nproblems in mathematics, such as the Erdos repeated distance problem and\nEuclidean distance matrix completion problems.",
        "positive": "Disorder-to-order transition of long fibers contained in evaporating\n  sessile drops: A liquid drop containing a long fiber is a complex system whose configuration\nis determined by an interplay of elastic stresses in the fiber and capillary\nforces due to the liquid. We study the morphological evolution of fibers that\nare much longer than the drop diameter in evaporating sessile drops. After\ninsertion, the fibers are either found in an ordered or disordered state, with\nincreasing disorder for increasing fiber length. Upon evaporation, the order\nincreases, in such a way that the final configuration deposited on the solid\nsurface is either a circle, an ellipse, or 8-shaped. The morphology of the\ndeposit depends on the fiber length and the elastocapillary length, both\nnon-dimensionalized with the characteristic drop size, which we classify in a\nmorphology regime map. The disorder-to-order transition allows depositing\nordered fiber structures on solid surfaces even in cases of a strongly\ndisordered state after fiber insertion. Combined with technologies such as\ninkjet printing, this process could open new avenues to decorate surfaces with\nfilamental structures whose morphology can be controlled by varying the fiber\nlength."
    },
    {
        "anchor": "Elastohydrodynamics of a soft coating under fluid-mediated loading by a\n  spherical probe: Motion of an object near a soft wall with intervening fluid is a canonical\nproblem in elastohydrodynamics, finding presence in subjects spanning biology\nto tribology. Particularly, motion of a sphere towards a soft substrate with\nintervening fluid is often encountered in the context of scanning probe\nmicroscopy. While there have been fundamental theoretical studies on this\nsetup, they have focussed on specific applications and thus enforced suitable\nsimplifications. Here we present a versatile semi-analytical framework for\nstudying the elastohydrodynamics of axisymmetric loading of a rigid sphere near\na soft elastic substrate coated on a rigid platform mediated by an aqueous\nelectrolytic solution. Three loading modes are considered - approach, recession\nand oscillatory. The framework incorporates - large oscillation frequency and\namplitude, two-way coupling between pressure and substrate deformation, and\npresence of DLVO forces. From computations using the framework, we gain\ninsights on the effects of DLVO forces, substrate thickness, substrate material\ncompressibility (quantified by Poisson's ratio) and high oscillation frequency\nfor different physical setups encountered in SPM and the likes. We list some\nkey observations. A substrate that is thicker and more compressible allows for\nlarger deformation, i.e. is effectively softer. Presence of DLVO forces lead to\nmagnification in force of upto two orders of magnitude and in substrate\ndeformation of upto an order of magnitude for oscillatory loading at low\nfrequencies and approach/recession loading at low speed. For oscillatory\nloading at high frequencies, DLVO forces do not appreciably affect the force\nand deflection behaviour of the system. Having demonstrated the versatility and\nutility of our framework, we expect it to evolve into a diverse and useful tool\nfor solving problems of soft-lubrication.",
        "positive": "Non-reciprocal forces and exceptional phase transitions in metric and\n  topological flocks: Many models of flocking involve alignment rules based on the mean orientation\nof neighboring particles, which we show introduces microscopic non-reciprocal\ninteractions. In the absence of this microscopic non-reciprocity an exceptional\nphase transition is predicted at low noise strength within the Toner-Tu\nframework of polar aligning matter; we demonstrate this transition via\nlarge-scale numerical simulations. By coarse-graining the microscopic\nnon-reciprocal forces found in more common models of flocking, we identify\nadditional terms in a hydrodynamic description which lead to a highly ordered\nclustered phase in metric models and restore the homogeneous flocking phase in\ntopological models."
    },
    {
        "anchor": "Phases and excitations of active rod-bead mixtures: simulations and\n  experiments: We present a large-scale numerical study, supplemented by experimental\nobservations, of a quasi-two-dimensional active system of polar rods and\nspherical beads confined between two horizontal plates and energised by\nvertical vibration. For low rod concentrations $\\Phi_r$ we observe a direct\nphase transition, as bead concentration $\\Phi_b$ is increased, from the\nisotropic phase to a homogeneous flock. For $\\Phi_r$ above a threshold value,\nan ordered band dense in both rods and beads occurs between the disordered\nphase and the homogeneous flock, in both experiments and simulations. Within\nthe size ranges accessible we observe only a single band, whose width increases\nwith $\\Phi_r$. Deep in the ordered state, we observe broken-symmetry \"sound\"\nmodes and giant number fluctuations. The direction-dependent sound speeds and\nthe scaling of fluctuations are consistent with the predictions of field\ntheories of flocking, but sound damping rates show departures from such\ntheories. At very high densities we see phase separation into rod-rich and\nbead-rich regions, both of which move coherently.",
        "positive": "End-pulled polymer translocation through a many-body flexible pore: This paper studies the features of a homopolymer translocating through a\nflexible pore. The channel is modeled as a monolayer tube composed by monomers\nwith two elastic parameters: spring-like two body interaction and bending three\nbody recall interaction. In order to guarantee the stability of the system, the\nmembrane is compounded by a lipid bilayer structure having hydrophobic body\n(internal), while the pore is hydrophilic in both edges. The polymer is\nend-pulled from the cis-side to the trans-side by a cantilever, to which is\nconnected through a spring able to measure the force acting on the polymer\nduring the translocation. All the structure reacts to the impacts of the\nmonomers of the polymer with vibrations generated by the movement of its\nconstituent bodies. In these conditions, the work done by the cantilever shows\na nonmonotonic behavior with the elastic constant, revealing a resonant-like\nbehavior in a parameter region. Moreover, the force spectroscopy registered as\na function of time, is able to record the main kinetics of the polymer\nprogression inside the pore."
    },
    {
        "anchor": "New exact solutions for the evaporation flux density of a small droplet\n  on a flat horizontal substrate with a contact angle in the range of 135-180\n  degrees: Previously [arXiv:2103.15582v3], an expression was proposed for the\nevaporation flux density of a small liquid droplet having the shape of an\naxisymmetric spherical segment deposited on a horizontal substrate. The\ndependence of the flux density on the polar angle was established for arbitrary\ncontact angles. This formula has the form of an integral and is rather\ncomplicated for use in modeling algorithms. An approximate expression was\nobtained for the evaporation flux density at small contact angles. However, the\nquestion of which simplified formulas should be appropriate to apply in other\nranges of contact angles, for example, in the case of obtuse angles remains\nopen. In this paper, we propose new exact solutions for the set of discrete\n\"hydrophobic\" contact angles. As an example, very simple exact expressions are\nobtained explicitly for the evaporation flux density for droplets with contact\nangles 135 and 150 degrees that do not contain integral dependencies. They can\nalso be used as approximate solutions for a narrow range of contact angles\naround the specified values.",
        "positive": "Phase behavior of a fluid with competing attractive and repulsive\n  interactions: Fluids in which the interparticle potential has a hard core, is attractive at\nmoderate separations, and repulsive at greater separations are known to exhibit\nnovel phase behavior, including stable inhomogeneous phases. Here we report a\njoint simulation and theoretical study of such a fluid, focusing on the\nrelationship between the liquid-vapor transition line and any new phases. The\nphase diagram is studied as a function of the amplitude of the attraction for a\ncertain fixed amplitude of the long ranged repulsion. We find that the effect\nof the repulsion is to substitute the liquid-vapor critical point and a portion\nof the associated liquid-vapor transition line, by two first order transitions.\nOne of these transitions separates the vapor from a fluid of spherical\nliquidlike clusters; the other separates the liquid from a fluid of spherical\nvoids. At low temperature, the two transition lines intersect one another and a\nvapor-liquid transition line at a triple point. While most integral equation\ntheories are unable to describe the new phase transitions, the Percus Yevick\napproximation does succeed in capturing the vapor-cluster transition, as well\nas aspects of the structure of the cluster fluid, in reasonable agreement with\nthe simulation results."
    },
    {
        "anchor": "Reentrant Melting of Lanes of Rough Circular Discs: We consider binary suspension of rough, circular particles in two dimensions\nunder athermal conditions. The mean density of the system is kept constant. The\nsuspension is subject to a time-independent external drive in response to which\none half of the particles are pulled along the field direction whereas the\nother half is pushed in the opposite direction. Simulating the system with\ndifferent magnitude of external drive in steady state, we obtain oppositely\nmoving macroscopic lanes only for a moderate range of external drive. Below as\nwell as above the range we obtain states with no lane. Hence we find that\nno-lane state re-enters along the axis of the external drive in the\nnon-equilibrium phase diagram corresponding to the laning transition, with\nvarying roughness of individual particles and external drive. Inter-particle\nfriction (contact dissipation) due to the roughness of the individual particle\nis the main player behind the re-entrance of no-lane state at high external\ndrives.",
        "positive": "Volume fraction determination of microgel composed of interpenetrating\n  polymer networks of PNIPAM and polyacrylic acid: Interpenetrated polymer network microgels, composed of crosslinked networks\nof poly(N-isopropylacrylamide) and polyacrylic acid (PAAc), have been\ninvestigated through rheological measurements at four different amounts of\npolyacrylic acid. Both PAAc content and crosslinking degree modify particle\ndimensions, mass and softness, thereby strongly affecting the volume fraction\nand the system viscosity. Here the volume fraction is derived from the flow\ncurves at low concentrations by fitting the zero-shear viscosity with the\nEinstein-Batchelor equation which provides a parameter k to shift weight\nconcentration to volume fraction. We find that particles with higher PAAc\ncontent and crosslinker are characterized by a greater value of k and therefore\nby larger volume fractions when compared to softer particles. The packing\nfractions obtained from rheological measurements are compared with those from\nstatic light scattering for two PAAc contents revealing a good agreement.\nMoreover, the behaviour of the viscosity as a function of packing fraction, at\nroom temperature, has highlighted an Arrhenius dependence for microgels\nsynthesized with low PAAc content and a Vogel-Fulcher-Tammann dependence for\nthe highest investigated PAAc concentration. A comparison with the hard spheres\nbehaviour indicates a steepest increase of the viscosity with decreasing\nparticles softness. Finally, the volume fraction dependence of the viscosity at\na fixed PAAc and at two different temperatures, below and above the volume\nphase transition, shows a quantitative agreement with the structural relaxation\ntime measured through dynamic light scattering indicating that IPN microgels\nsoftness can be tuned with PAAc and temperature and that, depending on particle\nsoftness, two different routes are followed."
    },
    {
        "anchor": "Inhomogeneous \"longitudinal\" plane waves in a deformed elastic material: A homogeneous isotropic compressible Hadamard material has the property that\nan infinitesimal longitudinal homogeneous plane wave may propagate in every\ndirection when the material is maintained in a state of arbitrary finite static\nhomogeneous deformation. Here, as regards the wave, 'homogeneous' means that\nthe direction of propagation of the wave is parallel to the direction of\neventual attenuation and 'longitudinal' means that the wave is linearly\npolarized in a direction parallel to the direction of propagation. In other\nwords, the displacement is of the form u = n cos k(n.x - ct), where n is a real\nvector.\n  It is seen that the Hadamard material is the most general one for which a\n'longitudinal' inhomogeneous plane wave may also propagate in any direction of\na predeformed body. Here, 'inhomogeneous' means that the wave is attenuated in\na direction distinct from the direction of propagation and 'longitudinal' means\nthat the wave is elliptically polarized in the plane containing these two\ndirections. In other words, the displacement is of the form u = Re {S exp[i\n(omega S.x - ct)]}, where S is a complex vector (or bivector).\n  Then a Generalized Hadamard material is introduced. It is the most general\nhomogeneous isotropic compressible material which allows the propagation of\ninfinitesimal 'longitudinal' inhomogeneous plane circularly polarized waves for\nall choices of the isotropic directional bivector.\n  Finally, the most general forms of response functions are found for\nhomogeneously deformed isotropic elastic materials in which 'longitudinal'\ninhomogeneous plane waves may propagate with a circular polarization in each of\nthe two planes of central circular section of the B^n-ellipsoid, where B is the\nleft Cauchy-Green strain tensor corresponding to the primary pure homogeneous\ndeformation.",
        "positive": "Calculating Pair Correlations from Random Particle Configurations: Particle pair-correlations are broadly used to describe particle\ndistributions in chemistry, physics, and material science. Many theoretical\nmethods require the pair-correlation to predict material properties such as\nfluid flow, thermal properties, or wave propagation. In all these applications\nit is either important to calculate a pair-correlation from specific particle\nconfigurations, or vice-versa: determine the likely particle configurations\nfrom a pair-correlation which is needed to fabricate a particulate material.\nMost available methods to calculate the pair-correlation from a particle\nconfiguration require that the configuration be very large to avoid effects\nfrom the boundary. Here we show how to avoid boundary effects even for small\nparticle configurations. Having small particle configurations leads to far more\nefficient numerical methods. We also demonstrate how to use techniques from\nsmooth nonlinear optimisation to quickly recover a particle configuration from\na pair-correlation."
    },
    {
        "anchor": "Stable Frank-Kasper phases of self-assembled, soft matter spheres: Single molecular species can self-assemble into Frank Kasper (FK) phases,\nfinite approximants of dodecagonal quasicrystals, defying intuitive notions\nthat thermodynamic ground states are maximally symmetric. FK phases are\nspeculated to emerge as the minimal-distortional packings of space-filling\nspherical domains, but a precise quantitation of this distortion and how it\naffects assembly thermodynamics remains ambiguous. We use two complementary\napproaches to demonstrate that the principles driving FK lattice formation in\ndiblock copolymers emerge directly from the strong-stretching theory of\nspherical domains, in which minimal inter-block area competes with minimal\nstretching of space-filling chains. The relative stability of FK lattices is\nstudied first using a diblock foam model with unconstrained particle volumes\nand shapes, which correctly predicts not only the equilibrium {\\sigma} lattice,\nbut also the unequal volumes of the equilibrium domains. We then provide a\nmolecular interpretation for these results via self-consistent field theory,\nilluminating how molecular stiffness regulates the coupling between\nintra-domain chain configurations and the asymmetry of local packing. These\nfindings shed new light on the role of volume exchange on the formation of\ndistinct FK phases in copolymers, and suggest a paradigm for formation of FK\nphases in soft matter systems in which unequal domain volumes are selected by\nthe thermodynamic competition between distinct measures of shape asymmetry.",
        "positive": "Bose-Einstein condensation of correlated atoms in a trap: The Bose-Einstein condensation of correlated atoms in a trap is studied by\nexamining the effect of inter-particle correlations to one-body properties of\natomic systems at zero temperature using a simplified formula for the\ncorrelated two body density distribution. Analytical expressions for the\ndensity distribution and rms radius of the atomic systems are derived using\nfour different expressions of Jastrow type correlation function. In one case,\nin addition, the one-body density matrix, momentum distribution and kinetic\nenergy are calculated analytically, while the natural orbitals and natural\noccupation numbers are also predicted in this case. Simple approximate\nexpressions for the mean square radius and kinetic energy are also given."
    },
    {
        "anchor": "Free volume distribution of nearly jammed hard sphere packings: We calculate the free volume distributions of nearly jammed packings of\nmonodisperse and bidisperse hard sphere configurations. These distributions\ndiffer qualitatively from those of the fluid, displaying a power law tail at\nlarge free volumes, which constitutes a distinct signature of nearly jammed\nconfigurations, persisting for moderate degrees of decompression. We reproduce\nand explain the observed distribution by considering the pair correlation\nfunction within the first coordination shell for jammed hard sphere\nconfigurations. We analyze features of the equation of state near jamming, and\ndiscuss the significance of observed asphericities of the free volumes to the\nequation of state.",
        "positive": "Influence of the Graft Length on Nanocomposite Structure and Interfacial\n  Dynamics: Both the dispersion state of nanoparticles (NPs) within polymer\nnanocomposites (PNCs) and the dynamical state of the polymer altered by the\npresence of the NP/polymer interfaces have a strong impact on the macroscopic\nproperties of PNCs. In particular, mechanical properties are strongly affected\nby percolation of hard phases, which may be NP networks, dynamically modified\npolymer regions, or combinations of both. In this article, the impact on\ndispersion and dynamics of surface modification of the NPs by short\nmonomethoxysilanes with eight carbons in the alkyl part (C8) is studied. As a\nfunction of grafting density and particle content, polymer dynamics is followed\nby broadband dielectric spectroscopy and analyzed by an interfacial layer\nmodel, whereas the particle dispersion is investigated by small-angle X-ray\nscattering and analyzed by reverse Monte Carlo simulations. NP dispersions are\nfound to be destabilized only at the highest grafting. The interfacial layer\nformalism allows the clear identification of the volume fraction of interfacial\npolymer, with its characteristic time. The strongest dynamical slow-down in the\npolymer is found for unmodified NPs, while grafting weakens this effect\nprogressively. The combination of all three techniques enables a unique\nmeasurement of the true thickness of the interfacial layer, which is ca. 5 nm.\nFinally, the comparison between longer (C18) and shorter (C8) grafts provides\nunprecedented insight into the efficacy and tunability of surface modification.\nIt is shown that C8-grafting allows for a more progressive tuning, which goes\nbeyond a pure mass effect."
    },
    {
        "anchor": "Phase transitions of a tethered membrane model on a torus with intrinsic\n  curvature: A tethered surface model is investigated by using the canonical Monte Carlo\nsimulation technique on a torus with an intrinsic curvature. We find that the\nmodel undergoes a first-order phase transition between the smooth phase and the\ncrumpled one.",
        "positive": "Exactly-solvable models for atom-molecule hamiltonians: We present a family of exactly-solvable generalizations of the\nJaynes-Cummings model involving the interaction of an ensemble of SU(2) or\nSU(1,1) quasi-spins with a single boson field. They are obtained from the\ntrigonometric Richardson-Gaudin models by replacing one of the SU(2) or SU(1,1)\ndegrees of freedom by an ideal boson. Application to a system of bosonic atoms\nand molecules is reported."
    },
    {
        "anchor": "Field theoretical representation of the Hohenberg-Kohn free energy for\n  fluids: To go beyond Gaussian approximation to the Hohenberg-Kohn free energy playing\nthe key role in the density functional theory (DFT), the density functional\n\\textit{integral} representation would be relevant, because field theoretical\napproach to perturbative calculations becomes available. Then the present\nletter first derives the associated Hamiltonian of density functional,\nexplicitly including logarithmic entropy term, from the grand partition\nfunction expressed by configurational integrals. Moreover, two things are done\nso that the efficiency of the obtained form may be revealed: to demonstrate\nthat this representation facilitates the field theoretical treatment of the\nperturbative calculation, and further to compare our perturbative formulation\nwith that of the DFT.",
        "positive": "Packing polydisperse colloids into crystals: when charge-dispersity\n  matters: Monte-Carlo simulations and small-angle x-ray scattering experiments were\nused to determine the phase diagram of aqueous dispersions of titratable\nnano-colloids with a moderate size polydispersity over a broad range of\nmonovalent salt concentrations, 0.5 mM $\\leq c_s \\leq$ 50 mM and volume\nfractions, $\\phi$. Under slow and progressive increase in $\\phi$, the\ndispersions freeze into a face-centered-cubic (fcc) solid followed unexpectedly\nby the formation of a body centered cubic (bcc) phase before to melt in a glass\nforming liquid. The simulations are found to predict very well these\nobservations. They suggest that the stabilization of the bcc solid at the\nexpense of the fcc phase at high $\\phi$ and $c_s$ results from the interaction\n(charge) polydispersity and vibrational entropy."
    },
    {
        "anchor": "Retrieving the saddle-splay elastic constant $K_{24}$ of nematic liquid\n  crystals from an algebraic approach: The physics of light interference experiments is well established for nematic\nliquid crystals. Using well-known techniques, it is possible to obtain\nimportant quantities, such as the differential scattering cross section and the\nsaddl-splay elastic constant $K_{24}$. However, the usual methods to retrieve\nthe latter involves an adjusting of computational parameters through the visual\ncomparisons between the experimental light interference pattern or a\n$^{2}H-NMR$ spectral pattern produced by an escaped-radial disclination, and\ntheir computational simulation counterparts. To avoid such comparisons, we\ndevelop an algebraic method for obtaining of saddle-splay elastic constant\n$K_{24}$. Considering an escaped-radial disclination inside a capillary tube\nwith radius $R_{0}$ of tens of micrometers, we use a metric approach to study\nthe propagation of the light (in the scalar wave approximation), near to the\nsurface of the tube and to determine the light interference pattern due to the\ndefect. The latter is responsible for the existence of a well-defined\ninterference peak associated to a unique angle $\\phi_{0}$. Since this angle\ndepends on factors such as refractive indexes, curvature elastic constants,\nanchoring regime, surface anchoring strength and radius $R_{0}$, the\nmeasurement of $\\phi_{0}$ from the interference experiments involving two\ndifferent radii allows us to algebraically retrieve $K_{24}$. Our method\nallowed us to give the first reported estimation of $K_{24}$ for the lyotropic\nchromonic liquid crystal Sunset Yellow FCF: $K_{24}=2.1\\ pN$.",
        "positive": "Building blocks of non-Euclidean ribbons: Size-controlled self-assembly\n  via discrete, frustrated particles: Geometric frustration offers a pathway to soft matter self-assembly with\ncontrollable finite sizes. While the understanding of frustration in soft\nmatter assembly derives almost exclusively from continuum elastic descriptions,\na current challenge is to understand the connection between microscopic\nphysical properties of misfitting ``building blocks\" and emergent assembly\nbehavior at mesoscale. We present and analyze a particle-based description of\nwhat is arguably the best studied example for frustrated soft matter assembly,\nnegative-curvature ribbon assembly, observed in both assemblies of chiral\nsurfactants and shape-frustrated nanoparticles. Based on our particle model,\nknown as {\\it saddle wedge monomers}, we numerically test the connection\nbetween microscopic shape and interactions of the misfitting subunits and the\nemergent behavior at the supra-particle scale, specifically focusing on the\npropagation and relaxation of inter-particle strains, the emergent role of\nextrinsic shape on frustrated ribbons and the equilibrium regime of finite\nwidth selection. Beyond the intuitive role of shape misfit, we show that\nself-limitation is critically dependent on the finite range of cohesive\ninteractions, with larger size finite assemblies requiring increasing\nshort-range interparticle forces. Additionally, we demonstrate that\nnon-linearities arising from discrete particle interactions alter self-limiting\nbehavior due to both strain-softening in shape-flattened assembly and partial\nyielding of highly strained bonds, which in turn may give rise to states of\nhierarchical, multidomain assembly. Tracing the regimes of frustration-limited\nassembly to the specific microscopic features of misfitting particle shapes and\ninteractions provides necessary guidance for translating the theory of\nsize-programmable assembly into design of intentionally-frustrated colloidal\nparticles."
    },
    {
        "anchor": "Elastic critical behaviour in a 3d model for polymer gels: The elastic response in polymeric gels is studied by means of a percolation\ndynamic model. By numerical simulations the fluctuations in the gyration radius\nand in the center of mass motion of the percolating cluster are determined.\nTheir scaling behaviour at the gelation threshold gives a critical exponent for\nthe elastic modulus $f \\sim 2.5 \\pm 0.1$ in agreement with the prediction $f =\nd \\nu$.",
        "positive": "Memory switching due to thermal noise in amorphous solids subject to\n  cyclic shear: The discovery that memory of particle configurations and plastic events can\nbe stored in amorphous solids subject to oscillatory shear has spurred research\ninto methods for storing and retrieving information from these materials.\nHowever, it is unclear to what extent the ability to store memory is affected\nby thermal fluctuations and other environmental noises, which are expected to\nbe relevant in realistic situations. Here, we show that while memory has a long\nlifetime at low temperatures, thermal fluctuations eventually lead to a\ncatastrophic loss of memory, resulting in the erasure of most or all of the\nstored information within a few forcing cycles. We observe that an escape from\nthe memory-retaining state (limit cycle) is triggered by a change in the\nswitching of plastic events, leading to a cascade of new plastic events that\nwere not present in the original limit cycle. The displacements from the new\nplastic events change the particle configuration which leads to the loss of\nmemory. We further show that the rate of escaping from a limit cycle increases\nin a non-Arrhenius manner as a function of temperature, and the probability of\nstaying in a limit cycle decays exponentially with an increase in the shearing\nfrequency. These results have important implications for memory storage since\nincreasing the temperature offers a means of effectively erasing existing\nmemories and allowing for the imprinting of new ones that can then be stored\nfor a long time at low temperatures."
    },
    {
        "anchor": "Stress partition and micro-structure in size-segregating granular flows: When a granular mixture involving grains of different sizes is shaken,\nsheared, mixed, or left to flow, grains tend to separate by sizes in a process\nknown as size segregation.\n  In this study, we explore the size segregation mechanism in granular chute\nflows in terms of pressure distribution and granular micro-structure.\nTherefore, 2D discrete numerical simulations of bi-disperse granular chute\nflows are systematically analysed. Based on the theoretical models by Gray and\nThornton 2005 and Hill and Tan 2014, we explore the stress partition in the\nphases of small and large grains, discriminating between contact stresses and\nkinetic stresses. Our results support both gravity-induced and\nshear-gradient-induced segregation mechanisms. However, we show that the\ncontact stress partition is extremely sensitive to the definition of the\npartial stress tensors, and more specifically, to the way mixed contacts (i.e.\ninvolving a small grain and a large grain) are handled, making conclusions on\ngravity-induced segregation uncertain.\n  By contrast, the computation of the partial kinetic stress tensors is robust.\nKinetic pressure partition exhibits a deviation from continuum mixture theory\nof a significantly larger amplitude than contact pressure, and display a clear\ndependence on the flow dynamics. Finally, using a simple approximation for the\ncontact partial stress tensors, we investigate how contact stress partition\nrelates with the flow micro-structure, and suggest that the latter may provide\nan interesting proxy for studying gravity-induced segregation.",
        "positive": "Magnetostatic response and field-controlled haloing in binary\n  superparamagnetic mixtures: Nowadays, magnetoresponsive soft materials, based not simply on magnetic\nnanoparticles, but rather on multiple components with distinct sizes and\nmagnetic properties, both in liquid and polymeric carriers, are becoming more\nand more wide-spread due to their unique and versatile macroscopic response to\nan applied magnetic field. The variability of the latter is related to a\ncomplex interplay of the magnetic interactions in a highly non-uniform internal\nfields caused by spatial inhomogeneity in multicomponent systems. In this work,\nwe present a combine analytical and simulation study of binary\nsuperparamagnetic systems, containing nanoclusters and dispersed single-domain\nnanoparticles, both in liquid and solid carrier matrices. We investigate the\nequilibrium magnetic response of these systems in wide ranges of concentrations\nand interaction energies. It turns out that, while the magnetisation of a\nbinary solid can be both above and below that of an ideal superparamagnetic\ngas, depending on the concentration of the dispersed phase and the\ninterparticle interactions, the system in a liquid carrier is highly\nmagnetically responsive. In liquid, a spatial redistribution of the initially\nhomogeneously dispersed phase in the vicinity of the nanocluster is observed --\nthe effect that is reminiscent of the so-called ``haloing'' effect previously\nobserved experimentally on micro- and milli-scales."
    },
    {
        "anchor": "Disordering to Order: de Vries behavior from a Landau theory for\n  smectics: We show that Landau theory for the isotropic, nematic, smectic A, and smectic\nC phases generically, but not ubiquitously, implies de Vries behavior. I.e., a\ncontinuous AC transition can occur with little layer contraction; the\nbirefringence decreases as temperature T is lowered above this transition, and\nincreases again below the transition. This de Vries behavior occurs in models\nwith unusually small orientational order, and is preceded by a first order I\n&#8722; A transition. A first order AC transition with elements of de Vries\nbehavior can also occur. These results correspond well with experimental work\nto date.",
        "positive": "Enhanced diffusion of tracer particles in nonreciprocal mixtures: We study the diffusivity of a tagged particle in a binary mixture of Brownian\nparticles with non-reciprocal interactions. Numerical simulations reveal that,\nfor a broad class of interaction potentials, non-reciprocity can significantly\nincrease the effective diffusion coefficient of tracer particles, and that this\ndiffusion enhancement is associated with a breakdown of the Einstein relation.\nThese observations are quantified and confirmed via two different and\ncomplementary analytical approaches: (i) a linearized stochastic density field\ntheory, which is particularly accurate in the limit of soft interactions; (ii)\na reduced two-body description, which is exact at leading order in the density\nof particles. The latter reveals that diffusion enhancement can be attributed\nto the formation of transiently propelled dimers of particles, whose cohesion\nand speed are controlled by the non-reciprocal interactions."
    },
    {
        "anchor": "Electrostatics of Colloidal Particles Confined in Nanochannels: Role of\n  Double-Layer Interactions and Ion-Ion Correlations: We perform computational investigations of electrolyte-mediated interactions\nof charged colloidal particles confined within nanochannels. We investigate the\nrole of discrete ion effects, valence, and electrolyte strength on colloid-wall\ninteractions. We find for some of the multivalent charge regimes that the\nlike-charged colloids and walls can have attractive interactions. We study in\ndetail these interactions and the free energy profile for the colloid-wall\nseparation. We find there are energy barriers and energy minima giving\npreferred colloid locations in the channel near the center and at a distance\nnear to but separated from the channel walls. We characterize contributions\nfrom surface overcharging, condensed layers, and overlap of ion double-layers.\nWe perform our investigations using Coarse-Grained Brownian Dynamics\nsimulations (BD), classical Density Functional Theory (cDFT), and mean-field\nPoisson-Boltzmann Theory (PB). We discuss the implications of our results for\nphenomena in nanoscale devices.",
        "positive": "Effects of Structural Inhomogeneity on Equilibration Processes in\n  Langevin Dynamics: In recent decades, computer experiments have led to an accurate and\nfundamental understanding of atomic and molecular mechanisms in fluids, such as\ndifferent kinds of relaxation processes toward steady physical states. In this\npaper, we investigate how exactly the configuration of initial states in a\nmolecular-dynamics simulation can affect the rates of decay toward equilibrium\nfor the widely-known Langevin canonical ensemble. For this purpose, we derive\nan original expression relating the system relaxation time {\\tau}_{sys} and the\nradial distribution function g(r) in the near-zero and high-density limit. We\nfound that for an initial state which is slightly marginally inhomogeneous in\nthe number density of atoms, the system relaxation time {\\tau}_{sys} is much\nlonger than that for the homogeneous case and an increasing function of the\nLangevin coupling constant, {\\gamma}. We also found during structural\nequilibration, g(r) at large distances approaches 1 from above for the\ninhomogeneous case and from below for the macroscopically homogeneous one."
    },
    {
        "anchor": "Simplicity of condensed matter at its core: Generic definition of a\n  Roskilde-simple system: The theory of isomorphs is reformulated by defining Roskilde-simple systems\n(those with isomorphs) by the property that the order of the potential energies\nof configurations at one density is maintained when these are scaled uniformly\nto a different density. Isomorphs remain curves in the thermodynamic phase\ndiagram along which structure, dynamics, and excess entropy are invariant,\nimplying that the phase diagram is effectively one-dimensional with respect to\nmany reduced-unit properties. In contrast to the original formulation of the\nisomorph theory, however, the density-scaling exponent is not exclusively a\nfunction of density and the isochoric heat capacity is not an exact isomorph\ninvariant. A prediction is given for the latter quantity's variation along the\nisomorphs. Molecular dynamics simulations of the Lennard-Jones and\nLennard-Jones Gaussian systems validate the new approach.",
        "positive": "Comment on \"Characterization of the tunneling conductance across DNA\n  bases\": In a recent article, Zikic {\\it et al.} [Phys. Rev. E {\\bf 74}, 011919\n(2006)] present first-principles calculations of the DNA nucleotides electrical\nconductance. They report qualitative and quantitative differences with previous\nwork, in particular with that of Zwolak and Di Ventra [Nano Lett. {\\bf 5}, 421\n(2005)] and Lagerqvist {\\it et al.} [Nano Lett. {\\bf 6}, 779 (2006)]. In this\ncomment we address the alleged discrepancies and show that Zikic {\\it et al.}\nhave seriously misread and misunderstood the existing literature. In addition,\nwe point out the deficiencies of their approach in calculating the conductance\nof nucleotides and the consequent erroneous conclusions they report."
    },
    {
        "anchor": "Rapid Equilibration by algorithmic quenching the ringing mode in\n  molecular dynamics: Long wavelength acoustic phonons are normally weakly coupled to other\nvibrational modes in a crystalline system. This is particularly problematic in\nmolecular dynamics calculations where vibrations at the system size scale are\ntypically excited at initiation. The equilibration time for these vibrations\ndepends on the strength of coupling to other modes, so is typically very long.\nA very simple deterministic method which avoids the use of is presented which\nremoves this problem.",
        "positive": "Swimmer suspensions on substrates: anomalous stability and long-range\n  order: We present a comprehensive theory of the dynamics and fluctuations of a\ntwo-dimensional suspension of polar active particles in an incompressible fluid\nconfined to a substrate. We show that, depending on the sign of a single\nparameter, a state with polar orientational order is anomalously stable (or\nanomalously unstable), with a nonzero relaxation (or growth) rate for angular\nfluctuations at zero wavenumber. This screening of the broken-symmetry mode in\nthe stable state does lead to conventional rather than giant number\nfluctuations as argued by Bricard et al., Nature ${\\bf 503}$, 95 (2013), but\ntheir bend instability in a splay-stable flock does not exist and the polar\nphase has long-range order in two dimensions. Our theory also describes\nconfined three-dimensional thin-film suspensions of active polar particles as\nwell as dense compressible active polar rods, and predicts a flocking\ntransition without a banding instability"
    },
    {
        "anchor": "Damage due to salt crystallization in porous media: We investigate salt crystallization in porous media that can lead to their\ndisintegration. For sodium sulfate we show for the first time experimentally\nthat when anhydrous crystals are wetted with water, there is very rapid growth\nof the hydrated form of sulfate in clusters that nucleate on anhydrous salt\nmicro crystals. The molar volume of the hydrated crystals being four times\nbigger, the growth of these clusters can generate stresses in excess of the\ntensile strength of the stone and lead therefore to damage.",
        "positive": "Pinning of crack fronts by hard and soft inclusions: a phase field study: Through tridimensonal numerical simulations of crack propagating in material\nwith an elastic moduli heterogeneity it is shown that the presence of a simple\ninclusion can affect dramatically the propagation of the crack. Both the\npresence of soft and hard inclusions can lead to the arrest of a crack front.\nHere the mechanism leading to the arrest of the crack are described and shown\nto depend on the nature of the inclusion. This is also the case in regimes\nwhere the presence of the inclusion leads to a slow down of the crack."
    },
    {
        "anchor": "Ferrimagnetic States of Na-K Alloy Clusters in Zeolite Low-Silica X: In zeolite low-silica X (LSX), beta-cages with the inside diameter of approx\n7 AA{} are arrayed in a diamond structure. Among them, supercages with the\ninside diameter of approx 13 AA{} are formed and arrayed in a diamond structure\nby the sharing of windows with the inside diameter of approx 8 AA{}. The\nchemical formula of zeolite LSX used in the present study is given by\nNa$_{x}$K$_{12-x}$Al$_{12}$Si$_{12}$O$_{48}$ per supercage (or beta-cage),\nwhere Na$_{x}$K$_{12-x}$ and Al$_{12}$Si$_{12}$O$_{48}$ are the exchangeable\ncations of zeolite LSX and the aluminosilicate framework, respectively. Na-K\nalloy clusters are incorporated in these cages by the loading of guest K metal\nat $n$K atoms per supercage (or beta-cage). A N'eel's N-type ferrimagnetism has\nbeen observed at $n = 7.8$ for $x = 4$. In the present paper, optical, magnetic\nand electrical properties are studied in detail mainly for $x = 4$.\nFerrimagnetic properties are observed at $6.5 < n < 8.5$. At the same time, the\nCurie constant suddenly increases. An optical reflection band of beta-cage\nclusters at 2.8 eV is observed at $n > 6.5$ in accordance with the sudden\nincrease in the Curie constant. An electrical resistivity indicates metallic\nvalues at $n$ gtrapprox 6, because a metallic state is realized in the energy\nband of supercage clusters. The ferrimagnetism is explained by the\nantiferromagnetic interaction between the magnetic sublattice of itinerant\nelectron ferromagnetism at supercage clusters and that of localized moments at\nbeta-cage clusters. The electrical resistivity in ferrimagnetic samples at $n =\n8.2$ for $x = 4$ increases extraordinarily at very low temperatures, such as\napprox $10^6$ times larger than the value at higher temperatures. Observed\nanomalies in the electrical resistivity resembles the Kondo insulator, but\nitinerant electrons of narrow energy band of supercage clusters are\nferromagnetic.",
        "positive": "Dynamics of Collapse of flexible Polyelectrolytes and Polyampholytes: We provide a theory for the dynamics of collapse of strongly charged\npolyelectrolytes (PEs) and flexible polyampholytes (PAs) using Langevin\nequation. After the initial stage, in which counterions condense onto PE, the\nmechanism of approach to the globular state is similar for PE and PA. In both\ninstances, metastable pearl-necklace structures form in characteristic time\nscale that is proportional to N^{4/5} where N is the number of monomers. The\nlate stage of collapse occurs by merger of clusters with the largest one\ngrowing at the expense of smaller ones (Lifshitz- Slyozov mechanism). The time\nscale for this process T_{COLL} N. Simulations are used to support the proposed\ncollapse mechanism for PA and PE."
    },
    {
        "anchor": "Hierarchical macro-nanoporous metals for leakage-free high-thermal\n  conductivity shape-stabilized phase change materials: Impregnation of Phase Change Materials (PCMs) into a porous medium is a\npromising way to stabilize their shape and improve thermal conductivity which\nare essential for thermal energy storage and thermal management of small-size\napplications, such as electronic devices or batteries. However, in these\ncomposites a general understanding of how leakage is related to the\ncharacteristics of the porous material is still lacking. As a result, the\nenergy density and the antileakage capability are often antagonistically\ncoupled. In this work we overcome the current limitations, showing that a high\nenergy density can be reached together with superior anti-leakage performance\nby using hierarchical macro-nanoporous metals for PCMs impregnation. By\nanalyzing capillary phenomena and synthesizing a new type of material, it was\ndemonstrated that a hierarchical trimodal macro-nanoporous metal (copper)\nprovides superior antileakage capability (due to strong capillary forces of\nnanopores), high energy density (90vol% of PCM load due to macropores) and\nimproves the charging/discharging kinetics, due to a three-fold enhancement of\nthermal conductivity. It was further demonstrated by CFD simulations that such\na composite can be used for thermal management of a battery pack and unlike\npure PCM it is capable of maintaining the maximum temperature below the safety\nlimit. The present results pave the way for the application of hierarchical\nmacro-nanoporous metals for high-energy density, leakage-free, and\nshape-stabilized PCMs with enhanced thermal conductivity. These innovative\ncomposites can significantly facilitate the thermal management of compact\nsystems such as electronic devices or high-power batteries by improving their\nefficiency, durability and sustainability",
        "positive": "Topological vortex formation in a Bose-Einstein condensate: Vortices were imprinted in a Bose-Einstein condensate using topological\nphases. Sodium condensates held in a Ioffe-Pritchard magnetic trap were\ntransformed from a non-rotating state to one with quantized circulation by\nadiabatically inverting the magnetic bias field along the trap axis. Using\nsurface wave spectroscopy, the axial angular momentum per particle of the\nvortex states was found to be consistent with $2\\hbar$ or $4\\hbar$, depending\non the hyperfine state of the condensate."
    },
    {
        "anchor": "Tautomeric equilibrium in condensed phases: We present an ab initio molecular dynamics (MD) investigation of the\ntautomeric equilibrium for aqueous solutions of glycine and acetone at\nrealistic experimental conditions. Metadynamics is used to accelerate proton\nmigration among tautomeric centers. Due to the formation of complex water-ion\nstructures involved the proton dynamics in the aqueous environment, standard\nenhanced sampling approaches may face severe limitations in providing a general\ndescription of the phenomenon. Recently, we developed a set of Collective\nVariables (CVs) designed to study protons transfer reactions in complex\ncondensed systems [Grifoni et al. PNAS, 2019, 116(10), 4054-4057]. In this work\nwe applied this approach to study proton dissociation dynamics leading to\ntautomeric interconversion of biologically and chemically relevant prototypical\nsystems, namely glycine and acetone in water. Although relatively simple from a\nchemical point of view, the results show that even for these small systems\ncomplex reaction pathways and non-trivial conversion dynamics are observed. The\ngenerality of our method allows obtaining these results without providing any\nprior information on the dissociation dynamics but only the atomic species that\ncan exchange protons in the process. Our results agree with literature\nestimates and demonstrate the general applicability of this method in the study\nof tautomeric reactions.",
        "positive": "Analysis of the anomalous mean field like properties of Gaussian core\n  model in terms of entropy: Studies of the Gaussian core model (GCM) have shown that it behaves like a\nmean field model and the properties are quite different from standard glass\nformer. In this work we investigate the entropies, namely the excess entropy\n($S_{ex}$) and the configurational entropy ($S_c$) and their different\ncomponents to address these anomalies. Our study corroborates most of the\nearlier observations and also sheds new light on the high and low temperature\ndynamics. We find that unlike in standard glass former where high temperature\ndynamics is dominated by two body correlation and low temperature by many body\ncorrelations, in GCM both high and low temperature dynamics are dominated by\nmany body correlations. We also find that the many body entropy which is\nusually positive at low temperatures and is associated with activated dynamics\nis negative in GCM suggesting suppression of activation. Interestingly despite\nsuppression of activation the Adam-Gibbs (AG) relation which describes\nactivated dynamics holds in GCM, thus suggesting a non-activated contribution\nin AG relation. We also find an overlap between the AG and mode coupling power\nlaw regime leading to a power law behaviour of $S_c$. From our analysis of this\npower law behaviour we predict that in GCM the high temperature dynamics will\ndisappear at dynamical transition temperature and below that there will be a\ntransition to the activated regime. Our study further reveals that the\nactivated regime in GCM is quite narrow."
    },
    {
        "anchor": "External field influence on semiflexible macromolecules: geometric\n  coupling: We suggested a geometric approach to address the external field influence on\nthe DNA molecules, described by the WLC model via geometric coupling. It\nconsists in the introduction of the effective metrics depending on the\npotential of the external field, with further re-definition of the arc-length\nparameter and of the extrinsic curvatures of the DNA molecules. It yields the\nnontrivial impact of the external field in the internal energy of\nmacromolecules. We give the Hamiltonian formulation of this model and perform\nits preliminary analysis in the redefinition of the initial energy density.",
        "positive": "Dynamical and orientational structural crossovers in low-temperature\n  glycerol: Mean square displacements of hydrogen atoms in glass-forming materials and\nproteins, as reported by incoherent elastic neutron scattering, show kinks in\ntheir temperature dependence. This crossover, known as the dynamical\ntransition, connects two approximately linear regimes. It is often assigned to\nthe dynamical freezing of subsets of molecular modes at the point of equality\nbetween their corresponding relaxation times and the instrumental observation\nwindow. The origin of the dynamical transition in glass-forming glycerol is\nstudied here by extensive molecular dynamics simulations. We find the dynamical\ntransition to occur for both the center of mass translations and the molecular\nrotations at the same temperature, insensitive to changes of the observation\nwindow. Both the translational and rotational dynamics of glycerol show a\ndynamic crossover from the structural to a secondary relaxation at the\ntemperature of the dynamical transition. A significant and discontinuous\nincrease in the orientational Kirkwood factor and in the dielectric constant is\nobserved in the same range of temperatures. We, however, do not find any\nindications of a true thermodynamic transition to an ordered low-temperature\nphase. We therefore suggest that all observed crossovers are dynamic in\ncharacter. The increase in the dielectric constant is related to the dynamic\nfreezing of dipolar domains on the time-scale of simulations."
    },
    {
        "anchor": "Applying a potential across a biomembrane: electrostatic contribution to\n  the bending rigidity and membrane instability: We investigate the effect on biomembrane mechanical properties due to the\npresence an external potential for a non-conductive non-compressible membrane\nsurrounded by different electrolytes. By solving the Debye-Huckel and Laplace\nequations for the electrostatic potential and using the relevant stress-tensor\nwe find: in (1.) the small screening length limit, where the Debye screening\nlength is smaller than the distance between the electrodes, the screening\ncertifies that all electrostatic interactions are short-range and the major\neffect of the applied potential is to decrease the membrane tension and\nincrease the bending rigidity; explicit expressions for electrostatic\ncontribution to the tension and bending rigidity are derived as a function of\nthe applied potential, the Debye screening lengths and the dielectric constants\nof the membrane and the solvents. For sufficiently large voltages the negative\ncontribution to the tension is expected to cause a membrane stretching\ninstability. For (2.) the dielectric limit, i.e. no salt (and small wavevectors\ncompared to the distance between the electrodes), when the dielectric constant\non the two sides are different the applied potential induces an effective\n(unscreened) membrane charge density, whose long-range interaction is expected\nto lead to a membrane undulation instability.",
        "positive": "Emergent Strain-Stiffening in Interlocked Granular Chains: Granular chain packings exhibit a striking emergent strain-stiffening\nbehavior despite the individual looseness of the constitutive chains. Using\nindentation experiments on such assemblies, we measure an exponential increase\nin the collective resistance force $F$ with the indentation depth $z$, and with\nthe square root of the number $\\mathcal{N}$ of beads per chain. These two\nobservations are respectively reminiscent of the self-amplification of friction\nin a capstan or in interleaved books, as well as the physics of polymers. The\nexperimental data are well captured by a novel model based on these two\ningredients. Specifically, the resistance force is found to vary according to\nthe universal relation: $\\log F \\sim \\mu \\sqrt{\\mathcal{N}} \\Phi^{11/8}z/ b $,\nwhere $\\mu$ is the friction coefficient between two elementary beads, $b$ is\ntheir size, and $\\Phi$ is the volume fraction of chain beads when semi-diluted\nin a surrounding medium of unconnected beads. Our study suggests that theories\nnormally confined to the realm of polymer physics at a molecular level can be\nused to explain phenomena at a macroscopic level. This class of systems enables\nthe study of friction in complex assemblies, with practical implications for\nthe design of new materials, the textile industry, and biology."
    },
    {
        "anchor": "Ultrahigh Charge Carrier Mobility in Nanotube Encapsulated Coronene\n  Stack: Achieving high charge carrier mobility is the holy grail of organic\nelectronics. In this letter we report a record charge carrier mobility of 14.93\ncm$^2$ V$^{-1}$s$^{-1}$ through a coronene stack encapsulated in a single\nwalled carbon nanotube (CNT) by using a multiscale modeling technique which\ncombines MD simulations, first principle calculations and Kinetic Monte Carlo\nsimulations. For the CNT having a diameter of 1.56 nm we find a highly ordered\ndefect free organization of coronene molecules inside the CNT which is\nresponsible for the high charge carrier mobility. The encapsulated coronene\nmolecules are correlated with a large correlation length of $\\sim $18 {\\AA}\nwhich is independent of the length of the coronene column. Our simulation\nfurther suggests that coronene molecules can spontaneously enter the CNT,\nsuggesting that the encapsulation is experimentally realizable.",
        "positive": "Coherent Structures in Dense Granular Flows: We present a theoretical derivation of a rheology for dense granular flow,\nbased on the process of inelastic collapse of neighboring particles. This\ncollapse creates regions of correlated motion, which control the viscous\nbehavior of the flow on a large scale. The result is a rheology that obeys the\nscaling form observed experimentally by Pouliquen and by the \"G.D.R. Midi\"\ngroup author. We identify the nature of the constraints imposed by inelastic\ncollapse on the grain-scale motions in the flow; finally, we show using an\nenergy cascade argument that the inelastic collapse need not proceed to the\nfinal endpoint in order for the correlations we have identified to build up."
    },
    {
        "anchor": "Fluid-fluid phase separation in a soft porous medium: Various biological and chemical processes lead to the nucleation and growth\nof non-wetting fluid bubbles within the pore space of a granular medium, such\nas the formation of gas bubbles in liquid-saturated lake-bed sediments. In\nsufficiently soft porous materials, the non-wetting nature of these bubbles can\nresult in the formation of open cavities within the granular solid skeleton.\nHere, we consider this process through the lens of phase separation, where\nthermomechanics govern the separation of the non-wetting phase from a\nfluid-fluid-solid mixture. We construct a phase-field model informed by\nlarge-deformation poromechanics, in which two immiscible fluids interact with a\nporoelastic solid skeleton. Our model captures the competing effects of\nelasticity and fluid-fluid-solid interactions. We use a phase-field damage\nmodel to capture the mechanics of the granular solid. As a model problem, we\nconsider an initial distribution of non-wetting fluid in the pore space that\nseparates into multiple cavities. We use simulations and linear-stability\nanalysis to identify the key parameters that control phase separation, the\nconditions that favour the formation of cavities, and the characteristic size\nof the resulting cavities.",
        "positive": "Minimal mechanism for cyclic templating of length-controlled copolymers\n  under isothermal conditions: The production of sequence-specific copolymers using copolymer templates is\nfundamental to the synthesis of complex biological molecules and is a promising\nframework for the synthesis of synthetic chemical complexes. Unlike the\nsuperficially similar process of self-assembly, however, the development of\nsynthetic systems that implement templated copying of copolymers under constant\nenvironmental conditions has been challenging. The main difficulty has been\novercoming product inhibition, or the tendency of products to adhere strongly\nto their templates - an effect that gets exponentially stronger with template\nlength. We develop coarse-grained models of copolymerisation on a finite-length\ntemplate and analyse them through stochastic simulation. We use these models\nfirst to demonstrate that product inhibition prevents reliable template\ncopying, and then ask how this problem can be overcome to achieve cyclic\nproduction of polymer copies of the right length and sequence in an autonomous\nand chemically-driven context. We find that a simple addition to the model is\nsufficient to generate far longer polymer products that initially form on, and\nthen separate from, the template. In this approach, some of the free energy of\npolymerisation is diverted into disrupting copy-template bonds behind the\nleading edge of the growing copy copolymer. By additionally weakening the final\ncopy-template bond at the end of the template, the model predicts that reliable\ncopying with a high yield of full-length, sequence-matched products is possible\nover large ranges of parameter space, opening the way to the engineering of\nsynthetic copying systems that operate autonomously."
    },
    {
        "anchor": "The nature of quasistatic deformation in granular materials: Strain in granular materials in quasistatic conditions under varying stress\noriginate in (I) contact deformation and (II) rearrangements of the contact\nnetwork. Depending on sample history and applied load, either mechanism might\ndominate. One may thus define rheological regimes I and II accordingly. Their\nproperties are presented and illustrated here with discrete numerical\nsimulation results on sphere packings. Understanding the microscopic physical\norigin of strain enables one to clarify such issues as the existence of\nmacroscopic elasticity, the approach to stress-strain relations in the large\nsystem limit and the sensitivity to noise.",
        "positive": "Generation of optical vorticity from topological defects: The propagation of an electromagnetic wave in a medium with a screw\ndislocation is studied. Adopting the formalism of differential forms, it is\nshown that torsion is responsible for quantized modes. Moreover, it is\ndemonstrated that the modes thus obtained have well defined orbital angular\nmomentum, opening the possibility to design liquid-crystal-based optical\ntweezers."
    },
    {
        "anchor": "Shape of a liquid front upon dewetting: We examine the profile of a liquid front of a film that is dewetting a solid\nsubstrate. Since volume is conserved, the material that once covered the\nsubstrate is accumulated in a rim close to the three phase contact line.\nTheoretically, such a profile of a Newtonian liquid resembles an exponentially\ndecaying harmonic oscillation that relaxes into the prepared film thickness.\nFor the first time, we were able to observe this behavior experimentally. A\nnon-Newtonian liquid - a polymer melt - however, behaves differently. Here,\nviscoelastic properties come into play. We will demonstrate that by analyzing\nthe shape of the rim profile. On a nm scale, we gain access to the rheology of\na non-Newtonian liquid.",
        "positive": "Nanoscale spatially resolved infrared spectra from single microdroplets: Droplet microfluidics has emerged as a powerful platform allowing a large\nnumber of individual reactions to be carried out in spatially distinct\nmicrocompartments. Due to their small size, however, the spectroscopic\ncharacterisation of species encapsulated in such systems remains challenging.\nIn this paper, we demonstrate the acquisition of infrared spectra from single\nmicrodroplets containing aggregation-prone proteins. To this effect, droplets\nare generated in a microfluidic flow-focussing device and subsequently\ndeposited in a square array onto a ZnSe prism using a micro stamp. After\ndrying, the solutes present in the droplets are illuminated locally by an\ninfrared laser through the prism, and their thermal expansion upon absorption\nof infrared radiation is measured with an atomic force microscopy tip, granting\nnanoscale resolution. Using this approach, we resolve structural differences in\nthe amide bands of the spectra of monomeric and aggregated lysozyme from single\nmicrodroplets with picolitre volume."
    },
    {
        "anchor": "Structural Landscapes in Geometrically Frustrated Smectics: A phenomenological free energy model is proposed to describe the behavior of\nsmectic liquid crystals, an intermediate phase that exhibits orientational\norder and layering at the molecular scale. Advantageous properties render the\nfunctional amenable to numerical simulation. The model is applied to a number\nof scenarios involving geometric frustration, leading to emergent structures\nsuch as focal conic domains and oily streaks and enabling detailed elucidation\nof the very rich energy landscapes that arise in these problems.",
        "positive": "Capillary and Viscous Fracturing During Drainage in Porous Media: Detailed understanding of the couplings between fluid flow and solid\ndeformation in porous media is crucial for the development of novel\ntechnologies relating to a wide range of geological and biological processes. A\nparticularly challenging phenomenon that emerges from these couplings is the\ntransition from fluid invasion to fracturing during multiphase flow. Previous\nstudies have shown that this transition is highly sensitive to fluid flow rate,\ncapillarity, and the structural properties of the porous medium. However, a\ncomprehensive characterization of the relevant fluid flow and material failure\nregimes does not exist. Here, we used our newly developed Multiphase\nDarcy-Brinkman-Biot framework to examine the transition from drainage to\nmaterial failure during viscously-stable multiphase flow in soft porous media\nin a broad range of flow, wettability, and solid rheology conditions. We\ndemonstrate the existence of three distinct material failure regimes controlled\nby non-dimensional numbers that quantify the balance of viscous, capillary, and\nstructural forces in the porous medium."
    },
    {
        "anchor": "Alignment Destabilizes Crystal Orders in Active Systems: We combine numerical and analytical methods to study two dimensional active\ncrystals formed by permanently linked swimmers and with two distinct alignment\ninteractions. The system admits a stationary phase with quasi long range\ntranslational order, as well as a moving phase with quasi-long range velocity\norder. The translational order in the moving phase is significantly influenced\nby alignment interaction. For Vicsek-like alignment, the translational order is\nshort-ranged, whereas the bond-orientational order is quasi-long ranged,\nimplying a moving hexatic phase. For elasticity-based alignment, the\ntranslational order is quasi-long ranged parallel to the motion and\nshort-ranged in perpendicular direction, whereas the bond orientational order\nis long-ranged. We also generalize these results to higher dimensions.",
        "positive": "Spatially selective Bragg scattering: a signature for vortices in\n  Bose-Einstein condensates: We demonstrate that Bragg scattering from a condensate can be sensitive to\nthe spatial phase distribution of the initial state. This allows preferential\nscattering from a selected spatial region, and provides a robust signature for\na vortex state. We develop an analytic model which accurately describes this\nphenomenon and we give quantitative predictions for current experimental\nconditions."
    },
    {
        "anchor": "Direct numerical analysis of dynamic facilitation in glass-forming\n  liquids: We propose a computational strategy to quantify the temperature evolution of\nthe timescales and lengthscales over which dynamic facilitation affects the\nrelaxation dynamics of glass-forming liquids at low temperatures, that requires\nno assumption about the nature of the dynamics. In two glass models, we find\nthat dynamic facilitation depends strongly on temperature, leading to a\nsubdiffusive spreading of relaxation events which we characterize using a\ntemperature-dependent dynamic exponent. We also establish that this temperature\nevolution represents a major contribution to the increase of the structural\nrelaxation time.",
        "positive": "Slow slip and the transition from fast to slow fronts in the rupture of\n  frictional interfaces: The failure of the population of micro-junctions forming the frictional\ninterface between two solids is central to fields ranging from biomechanics to\nseismology. This failure is mediated by the propagation along the interface of\nvarious types of rupture fronts, covering a wide range of velocities. Among\nthem are so-called slow fronts, which are recently discovered fronts much\nslower than the materials' sound speeds. Despite intense modelling activity,\nthe mechanisms underlying slow fronts remain elusive. Here, we introduce a\nmulti-scale model capable of reproducing both the transition from fast to slow\nfronts in a single rupture event and the short-time slip dynamics observed in\nrecent experiments. We identify slow slip immediately following the arrest of a\nfast front as a phenomenon sufficient for the front to propagate further at a\nmuch slower pace. Whether slow fronts are actually observed is controlled both\nby the interfacial stresses and by the width of the local distribution of\nforces among micro-junctions. Our results show that slow fronts are\nqualitatively different from faster fronts. Since the transition from fast to\nslow fronts is potentially as generic as slow slip, we anticipate that it might\noccur in the wide range of systems in which slow slip has been reported,\nincluding seismic faults."
    },
    {
        "anchor": "Hydrodynamic alignment of microswimmers in pipes: We investigate the dynamics of model microswimmers under confinement, in\ncylindrical geometries, by means of three dimensional direct numerical\ncalculations with fully resolved hydrodynamics. Such swimmers are known to show\ncollective alignment in bulk, and we confirmed that similar alignment can be\nobserved even in pipes, although the volume fraction dependency shows\nqualitative differences. By comparing the structural information, we\ninvestigated the cause of such differences. We found an order/disorder phase\ntransition for a specific type of swimmers, as the size of the pipe becomes\ncomparable to the size of the swimmers. Such dynamics are found not to depend\non the geometry of confinement.",
        "positive": "Active Matter: The term active matter describes diverse systems, spanning macroscopic (e.g.\nshoals of fish and flocks of birds) to microscopic scales (e.g. migrating\ncells, motile bacteria and gels formed through the interaction of nanoscale\nmolecular motors with cytoskeletal filaments within cells). Such systems are\noften idealizable in terms of collections of individual units, referred to as\nactive particles or self-propelled particles, which take energy from an\ninternal replenishable energy depot or ambient medium and transduce it into\nuseful work performed on the environment, in addition to dissipating a fraction\nof this energy into heat. These individual units may interact both directly as\nwell as through disturbances propagated via the medium in which they are\nimmersed. Active particles can exhibit remarkable collective behaviour as a\nconsequence of these interactions, including non-equilibrium phase transitions\nbetween novel dynamical phases, large fluctuations violating expectations from\nthe central limit theorem and substantial robustness against the disordering\neffects of thermal fluctuations. In this chapter, following a brief summary of\nexperimental systems which may be classified as examples of active matter, I\ndescribe some of the principles which underlie the modeling of such systems."
    },
    {
        "anchor": "Crystallizing hard-sphere glasses by doping with active particles: Crystallization and vitrification are two different routes to form a solid.\nNormally these two processes suppress each other, with the glass transition\npreventing crystallization at high density (or low temperature). This is even\ntrue for systems of colloidal hard spheres, which are commonly used as building\nblocks for novel functional materials with potential applications, e.g.\nphotonic crystals. By performing Brownian dynamics simulations of glassy\nsystems consisting of mixtures of active and passive hard spheres, we show that\nthe crystallization of such hard-sphere glasses can be dramatically promoted by\ndoping the system with small amounts of active particles. Surprisingly, even\nhard-sphere glasses of packing fraction up to $\\phi = 0.635$ crystallize, which\nis around $0.5\\%$ below the random close packing at $\\phi \\simeq 0.64$. Our\nresults suggest a novel way of fabricating crystalline materials from\n(colloidal) glasses. This is particularly important for materials that get\neasily kinetically trapped in glassy states, and crystal nucleation hardly\noccurs.",
        "positive": "Memory effects in the relaxation of the Gaussian trap model: We investigate the memory effect in a simple model for glassy relaxation, a\ntrap model with a Gaussian density of states. In this model thermal equilibrium\nis reached at all finite temperatures and therefore we can consider jumps from\nlow to high temperatures in addition to the quenches usually considered in\naging studies. We show that the evolution of the energy following the\nKovacs-protocol can approximately be expressed as a difference of two\nmonotonously decaying functions and thus show the existence of a so-called\nKovacs hump whenever these functions are not single exponentials. It is well\nestablished that the Kovacs effect also occurs in the linear response regime\nand we show that most of the gross features do not change dramatically when\nlarge temperature jumps are considered. However, there is one distinguishing\nfeature that only exists beyond the linear regime which we discuss in detail.\nFor the memory experiment with 'inverted' temperatures, i.e. jumping up and\nthen down again, we find a very similar behavior apart from an opposite sign of\nthe hump."
    },
    {
        "anchor": "Preferential affinity of calcium ions to charged phosphatidic-acid\n  surface from a mixed calcium/barium solution: X-ray reflectivity and\n  fluorescence studies: X-ray reflectivity and fluorescence near total reflection experiments were\nperformed to examine the affinities of divalent ions ($\\mathrm{Ca^{2+}}$ and\n$\\mathrm{Ba^{2+}}$) from aqueous solution to a charged phosphatidic-acid (PA)\nsurface. A phospholipid (1,2-Dimyristoyl-sn-Glycero-3-Phosphate, DMPA), spread\nas a monolayer at the air/water interface, was used to form and control the\ncharge density at the interface. We find that for solutions of the pure salts\n(i.e., $\\mathrm{CaCl_{2}}$ and $\\mathrm{BaCl_{2}}$), the number of bound ions\nper DMPA at the interface is saturated at concentrations that exceed\n$\\mathrm{10^{-3}M}$. For a 1:1 $\\mathrm{Ca^{2+}/Ba^{2+}}$ mixed solutions, we\nfind that the bound $\\mathrm{Ca^{2+}/Ba^{2+}}$ ratio at the interface is 4:1.\nIf the only property determining charge accumulation near PA were the ionic\ncharges, the concentration of mixed $\\mathrm{Ca^{2+}/Ba^{2+}}$ at the interface\nwould equal that of the bulk. Our results show a clear specific affinity of PA\nfor Ca compared to Ba. We provide some discussion on this issues as well as\nsome implications for biological systems. Although our results indicate an\nexcess of counterion charge with respect to the surface charge, that is, charge\ninversion, the analysis of both reflectivity and fluorescence do not reveal\nexcess of co-ions (namely, $\\mathrm{Cl^{-}}$ or $\\mathrm{I}^{-}$).",
        "positive": "Inverted critical adsorption of polyelectrolytes in confinement: What are the fundamental laws for the adsorption of charged polymers onto\noppositely charged surfaces, for convex, planar, and concave geometries? This\nquestion is at the heart of surface coating applications, various complex\nformation phenomena, as well as in the context of cellular and viral\nbiophysics. It has been a long-standing challenge in theoretical polymer\nphysics; for realistic systems the quantitative understanding is however often\nachievable only by computer simulations. In this study, we present the findings\nof such extensive Monte-Carlo in silico experiments for polymer-surface\nadsorption in confined domains. We study the inverted critical adsorption of\nfinite-length polyelectrolytes in three fundamental geometries: planar slit,\ncylindrical pore, and spherical cavity. The scaling relations extracted from\nsimulations for the critical surface charge density $\\sigma_c$-defining the\nadsorption-desorption transition-are in excellent agreement with our analytical\ncalculations based on the ground-state analysis of the Edwards equation. In\nparticular, we confirm the magnitude and scaling of $\\sigma_c$ for the concave\ninterfaces versus the Debye screening length $1/\\kappa$ and the extent of\nconfinement $a$ for these three interfaces for small $\\kappa a$ values. For\nlarge $\\kappa a$ the critical adsorption condition approaches the planar limit.\nThe transition between the two regimes takes place when the radius of surface\ncurvature or half of the slit thickness $a$ is of the order of $1/\\kappa$. We\nalso rationalize how $\\sigma_c(\\kappa)$ gets modified for semi-flexible versus\nflexible chains under external confinement. We examine the implications of the\nchain length onto critical adsorption-the effect often hard to tackle\ntheoretically-putting an emphasis on polymers inside attractive spherical\ncavities."
    },
    {
        "anchor": "Protein motors induced enhanced diffusion in intracellular transport: Diffusion of transported particles in the intracellular medium is described\nby means of a generalized diffusion equation containing forces due to the\ncytoskeleton network and to the protein motors. We find that the enhanced\ndiffusion observed in experiments depends on the nature of the force exerted by\nthe protein motors and on parameters characterizing the intracellular medium\nwhich is described in terms of a generalized Debye spectrum for the noise\ndensity of states.",
        "positive": "Phase Transition between the Cholesteric and Twist Grain Boundary C\n  Phases: The upper critical temperature Tc2 for the phase transition between the\nCholesteric phase (N*) and the Twist Grain Boundary C phase with the layer\ninclination tilted to the pitch axis (TGBct) in thermotropic liquid crystals is\ndetermined by the mean field Chen-Lubensky approach. We show that the N*-TGBct\nphase transition is split in two with the appearance of either the TGBA or the\nTGB2q phase in a narrow temperature interval below Tc2. The latter phase is\nnovel in being superposed from two degenerate\n  TGBct phases with different (left and right) layers inclinations to the pitch\naxis."
    },
    {
        "anchor": "On the effect of surfactant adsorption and viscosity change on apparent\n  slip in hydrophobic microchannels: Substantial experimental, theoretical, as well as numerical effort has been\ninvested to understand the effect of boundary slippage in microfluidic devices.\nHowever, even though such devices are becoming increasingly important in\nscientific, medical, and industrial applications, a satisfactory understanding\nof the phenomenon is still lacking. This is due to the extremely precise\nexperiments needed to study the problem and the large number of tunable\nparameters in such systems.\n  In this paper we apply a recently introduced algorithm to implement\nhydrophobic fluid-wall interactions in the lattice Boltzmann method. We find a\npossible explanation for some experiments observing a slip length depending on\nthe flow velocity which is contradictory to many theoretical results and\nsimulations. Our explanation is that a velocity dependent slip can be detected\nif the flow profile is not fully developed within the channel, but in a\ntransient state.\n  Further, we show a decrease of the measured slip length with increasing\nviscosity and demonstrate the effect of adding surfactant to a fluid flow in a\nhydrophobic microchannel. The addition of surfactant can shield the repulsive\npotential of hydrophobic walls, thus lowering the amount of slip with\nincreasing surfactant concentration.",
        "positive": "Effects of coordination and stiffness scale-separation in disordered\n  elastic networks: Many fibrous materials are modeled as elastic networks featuring a\nsubstantial separation between the stiffness scales that characterize different\nmicroscopic deformation modes of the network's constituents. This scale\nseparation has been shown to give rise to emergent complexity in these systems'\nlinear and nonlinear mechanical response. Here we study numerically a simple\nmodel featuring said stiffness scale-separation in two-dimensions and show that\nits mechanical response is governed by the competition between the\ncharacteristic stiffness of collective nonphononic soft modes of the stiff\nsubsystem, and the characteristic stiffness of the soft interactions. We\npresent and rationalize the behavior of the shear modulus of our complex\nnetworks across the unjamming transition at which the stiff subsystem alone\nloses its macroscopic mechanical rigidity. We further establish a relation in\nthe soft-interaction-dominated regime between the shear modulus, the\ncharacteristic frequency of nonphononic vibrational modes, and the mesoscopic\ncorrelation length that marks the crossover between a disorder-dominated\nresponse to local mechanical perturbations in the near-field, and a linear,\ncontinuum-like response in the far field. The effects of spatial dimension on\nthe observed scaling behavior are discussed, in addition to the interplay\nbetween stiffness scales in strain-stiffened networks, which are relevant to\nthe nonlinear mechanics of non-Brownian biopolymer networks."
    },
    {
        "anchor": "Flow fields in soap films: relating surface viscosity and film thickness: We follow the diffusive motion of colloidal particles in soap films with\nvarying $h/d$, where $h$ is the thickness of the film and $d$ the diameter of\nthe particles. The hydrodynamics of these films are determined by looking at\nthe correlated motion of pairs of particles as a function of separation $R$.\nThe Trapeznikov approximation [A. A. Trapeznikov, \\emph{PICSA} (1957)] is used\nto model soap films as an effective interface in contact with bulk air phases,\nthat behaves as a 2D fluid. The flow fields determined from correlated particle\nmotions show excellent agreement with what is expected for the theory of 2D\nfluids for all our films where $0.6 \\leq h/d \\leq 14.3$, with the surface\nviscosity matching that predicted by Trapeznikov. However, for thicker films\nwith $h/d > 7 \\pm 3$, single particle motion is faster than expected.\nAdditionally, while the flow fields still match those expected for 2D fluids,\nthe parameters of these flow fields change markedly for thick films. Our\nresults indicate a transition from 2D to 3D fluid-like behavior occurs at this\nvalue of $h/d$.",
        "positive": "Magnetic enhancement of Co$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$ spinel oxide by\n  mechanical milling: We report the magnetic properties of mechanically milled\nCo$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$ spinel oxide. After 24 hours milling of the\nbulk sample, the XRD spectra show nanostructure with average particle size\n$\\approx$ 20 nm. The as milled sample shows an enhancement in magnetization and\nordering temperature compared to the bulk sample. If the as milled sample is\nannealed at different temperatures for the same duration, recrystallization\nprocess occurs and approaches to the bulk structure on increasing the annealing\ntemperatures. The magnetization of the annealed samples first increases and\nthen decreases. At higher annealing temperature ($\\sim$ 1000$^{0}$C) the system\nshows two coexisting magnetic phases {\\it i.e.}, spin glass state and\nferrimagnetic state, similar to the as prepared bulk sample. The room\ntemperature M\\\"{o}ssbauer spectra of the as milled sample, annealed at\n300$^{0}$C for different durations (upto 575 hours), suggest that the observed\nchange in magnetic behaviour is strongly related with cations redistribution\nbetween tetrahedral (A) and octahedral (O) sites in the spinel structure. Apart\nfrom the cation redistribution, we suggest that the enhancement of\nmagnetization and ordering temperature is related with the reduction of B site\nspin canting and increase of strain induced anisotropic energy during\nmechanical milling."
    },
    {
        "anchor": "Using magnetic levitation to produce cryogenic targets for inertial\n  fusion energy: experiment and theory: We present experimental and theoretical studies of magnetic levitation of\nhydrogen gas bubble surrounded by liquid hydrogen confined in a\nsemi-transparent spherical shell of 3 mm internal diameter. Such shells are\nused as targets for the inertial confinement fusion (ICF), for which a\nhomogeneous (within a few percent) layer of a hydrogen isotope should be\ndeposited on the internal walls of the shells. The gravity does not allow the\nhydrogen layer thickness to be homogeneous. To compensate this gravity effect,\nwe have used a non-homogeneous magnetic field created by a 10 T superconductive\nsolenoid. Our experiments show that the magnetic levitation homogenizes the\nthickness of liquid hydrogen layer. However, the variation of the layer\nthickness is very difficult to measure experimentally. Our theoretical model\nallows the exact shape of the layer to be predicted. The model takes into\naccount the surface tension, gravity, van der Waals, and magnetic forces. The\nnumerical calculation shows that the homogeneity of the layer thickness is\nsatisfactory for the ICF purposes.",
        "positive": "Banana and pizza-slice-shaped mesogens give a new constrained\n  ferromagnet universality class: It has been known that at high density, the local orientation of\nbanana-shaped molecules shows a spontaneously bent state, giving rise to\ninteresting liquid-crystalline phases such as splay-bend and twist-bend. This\nspontaneous bend can be modelled theoretically by allowing the bend elastic\nconstant in the Frank elastic energy to become negative. Here we extend this\nidea to polar banana and pizza-slice-shaped molecules which can also splay\nspontaneously. By allowing both splay and bend elastic constants to be negative\nwe discovered two additional new liquid crystalline phases. In particular,\nusing renormalization group technique, we showed that the phase transition\nbelongs to a new constrained ferromagnet universality class."
    },
    {
        "anchor": "Rapid design of fully soft deployable structures via kirigami cuts and\n  active learning: Soft deployable structures - unlike conventional piecewise rigid deployables\nbased on hinges and springs - can assume intricate 3-D shapes, thereby enabling\ntransformative technologies in soft robotics, shape-morphing architecture, and\npop-up manufacturing. Their virtually infinite degrees of freedom allow precise\ncontrol over the final shape. The same enabling high dimensionality, however,\nposes a challenge for solving the inverse design problem involving this class\nof structures: to achieve desired 3D structures it typically requires\nmanufacturing technologies with extensive local actuation and control during\nfabrication, and a trial and error search over a large design space. We address\nboth of these shortcomings by first developing a simplified planar fabrication\napproach that combines two ingredients: strain mismatch between two layers of a\ncomposite shell and kirigami cuts that relieves localized stress. In principle,\nit is possible to generate targeted 3-D shapes by designing the appropriate\nkirigami cuts and selecting the right amount of prestretch, thereby eliminating\nthe need for local control. Second, we formulate a data-driven physics-guided\nframework that reduces the dimensionality of the inverse design problem using\nautoencoders and efficiently searches through the ``latent\" parameter space in\nan active learning approach. We demonstrate the effectiveness of the rapid\ndesign procedure via a range of target shapes, such as peanuts, pringles,\nflowers, and pyramids. Tabletop experiments are conducted to fabricate the\ntarget shapes. Experimental results and numerical predictions from our\nframework are found to be in good agreement.",
        "positive": "Magnetically actuated artificial microswimmers as mobile microparticle\n  manipulators: Micro-scale swimming robots have been envisaged for many medical applications\nsuch as targeted drug delivery, where the microrobot will be expected to\nnavigate in a fluid through channels carrying a payload. Alternatively, in many\ncases, such a payload does not have to be physically bound to the swimmer, but\nmay be instead manipulated and steered through the channel by the microrobot.\nWe investigate this problem of contactless manipulation of a microparticle by\nmobile microswimmer in a fluid at low Reynolds number. We consider a model of a\nmagnetically actuated artificial microswimmer, whose locomotion through a fluid\ninduces a disturbance velocity field in the fluid, that then acts to propel a\ncargo particle in its vicinity. The problem investigated in this paper is\ntherefore one of coupled locomotion-manipulation of two bodies in a fluid. The\nmagnetic swimmer's motion is actuated by an externally applied magnetic field\nof constant strength but whose direction rotates at a constant rate in a plane.\nThe swimmer propels itself in the direction perpendicular to this plane if the\nfrequency associated with the periodic magnetic field is above a critical\nfrequency. Below this critical frequency, the swimmer tumbles in place without\nnet locomotion. The coupled fluid-swimmer-cargo particle dynamics are solved\nnumerically using the method of Stokesian dynamics. The induced motion of the\ncargo particle is shown to be controllable. This is achieved by switching the\nplanes of rotation of the magnetic field and switching frequency of the\nmagnetic field above and below the critical frequency. While a swimmer with a\nspecific geometry has been used in the model, the results of this paper are\napplicable to swimmers with other geometries and means of propulsion. The\nresults of this paper show that microswimmers can be utilized as mobile\nmanipulators of microparticles in a fluid."
    },
    {
        "anchor": "Search for a liquid-liquid critical point in models of silica: Previous research has indicated the possible existence of a liquid-liquid\ncritical point (LLCP) in models of silica at high pressure. To clarify this\ninteresting question we run extended molecular dynamics simulations of two\ndifferent silica models (WAC and BKS) and perform a detailed analysis of the\nliquid at temperatures much lower than those previously simulated. We find no\nLLCP in either model within the accessible temperature range, although it is\nclosely approached in the case of the WAC potential near 4000 K and 5 GPa.\nComparing our results with those obtained for other tetrahedral liquids, and\nrelating the average Si-O-Si bond angle and liquid density at the model glass\ntemperature to those of the ice-like beta-cristobalite structure, we conclude\nthat the absence of a critical point can be attributed to insufficient\n\"stiffness\" in the bond angle. We hypothesize that a modification of the\npotential function to mildly favor larger average bond angles will generate a\nLLCP in a temperature range that is accessible to simulation. The tendency to\ncrystallize in these models is extremely weak in the pressure range studied,\nalthough this tendency will undoubtedly increase with increasing stiffness.",
        "positive": "Continuum mechanics at nanoscale. A tool to study trees' watering and\n  recovery: The cohesion-tension theory expounds the crude sap ascent thanks to the\nnegative pressure generated by evaporation of water from leaves. Nevertheless,\ntrees pose multiple challenges and seem to live in unphysical conditions: the\nnegative pressure increases cavitation; it is possible to obtain a water\nequilibrium between connected parts where one is at a positive pressure and the\nother one is at negative pressure; no theory is able to satisfactorily account\nfor the refilling of vessels after embolism events. A theoretical form of our\npaper in the Journal of Theoretical Biology is proposed together with new\nresults: a continuum mechanics model of the disjoining pressure concept refers\nto the Derjaguin School of physical chemistry. A comparison between liquid\nbehaviour both in tight-filled microtubes and in liquid thin-films is offered\nwhen the pressure is negative in liquid bulks and is positive in liquid\nthin-films and vapour bulks. In embolized xylem microtubes, when the air-vapour\npocket pressure is greater than the air-vapour bulk pressure, a refilling flow\noccurs between the air-vapour domains to empty the air-vapour pockets although\nthe liquid-bulk pressure remains negative. The model has a limit of validity\ntaking the maximal size of trees into account. These results drop inkling that\nthe disjoining pressure is an efficient tool to study biological liquids in\ncontact with substrates at a nanoscale range."
    },
    {
        "anchor": "Liquid dispensing and writing by a nano-grooved pin: Liquid dispensing and writing in the extremely small size regime are\nimportant for applications in many current technologies, such as micro/nano\nfabrication, biological/chemical patterning and analysis, and drug discovery.\nMost of current dispensing/writing methods can be sorted into a category of\nliquid flowing through tiny tubes or nozzles that requires inputting an impulse\nenergy, which leads to complex procedures, expensive equipment and narrow\nmaterial applicability, especially for biomaterials. Here, we report a method\nthat may lead to a new category: liquid flows over the tapered surface of a pin\nwith longitudinal nano grooves on the surface to uninterruptedly perform\ndroplet dispensing and direct writing. The dispensed droplet diameters were\ncontrollable from several microns down to 150 nm, and the written line heights\nwere as low as 5 nm. The mechanism underlying automatic liquid storage on\nconical surface and spontaneous liquid transport through nano grooves is\nrevealed and well modeled by a simple relationship. Furthermore, the\nnano-grooved pins are much simpler and cheaper in fabrication than nanoscale\ntubes and nozzles, and pins have much depressed clogging problems that are\ntypically troublesome for tubes and nozzles. Our new strategy may constitute a\nbasis for creating liquid dispensing/writing technologies that are\nsimultaneously smaller, simpler, faster and applicable for more types of\nmaterials.",
        "positive": "Avalanches in Strained Amorphous Solids: Does Inertia Destroy Critical\n  Behavior?: Simulations are used to determine the effect of inertia on athermal shear of\na two-dimensional binary Lennard-Jones glass. In the quasistatic limit, shear\noccurs through a series of rapid avalanches. The distribution of avalanches is\nanalyzed using finite-size scaling with thousands to millions of particles.\nInertia takes the system to a new underdamped universality class rather than\ndriving the system away from criticality. Scaling exponents are determined for\nthe underdamped and overdamped limits and a critical damping that separates the\ntwo regimes. Systems are in the overdamped universality class even when most\nvibrational modes are underdamped."
    },
    {
        "anchor": "Poisson-Fermi Formulation of Nonlocal Electrostatics in Electrolyte\n  Solutions: We present a nonlocal electrostatic formulation of nonuniform ions and water\nmolecules with interstitial voids that uses a Fermi-like distribution to\naccount for steric and correlation effects in electrolyte solutions. The\nformulation is based on the volume exclusion of hard spheres leading to a\nsteric potential and Maxwell's displacement field with Yukawa-type interactions\nresulting in a nonlocal electric potential. The classical Poisson-Boltzmann\nmodel fails to describe steric and correlation effects important in a variety\nof chemical and biological systems, especially in high field or large\nconcentration conditions found in and near binding sites, ion channels, and\nelectrodes. Steric effects and correlations are apparent when we compare\nnonlocal Poisson-Fermi results to Poisson-Boltzmann calculations in electric\ndouble layer and to experimental measurements on the selectivity of potassium\nchannels for K+ over Na+. The present theory links atomic scale descriptions of\nthe crystallized KcsA channel with macroscopic bulk conditions. Atomic\nstructures and macroscopic conditions determine complex functions of great\nimportance in biology, nanotechnology, and electrochemistry.",
        "positive": "High pressure induced phase transition and superdiffusion in anomalous\n  fluid confined in flexible nanopores: The behavior of a confined spherical symmetric anomalous fluid under high\nexternal pressure was studied with Molecular Dynamics simulations. The fluid is\nmodeled by a ore-softened potential with two characteristic length scales,\nwhich in bulk reproduces the dynamical, thermodynamical and structural\nanomalous behavior observed for water and other anomalous fluids. Our findings\nshow that this system has a superdiffusion regime for sufficient high pressure\nand low temperature. As well, our results indicate hat this superdiffusive\nregime is strongly related with the fluid structural properties and the\nsuperdiffusion to diffusion transition is a first order phase transition. We\nshow how the simulation time and statistics are important to obtain the correct\ndynamical behavior of the confined fluid. Our results are discussed in the\nbasis of the two length scales."
    },
    {
        "anchor": "Screening and collective effects in randomly pinned fluids: A new\n  theoretical framework: We propose a theoretical framework for the dynamics of bulk isotropic\nhard-sphere systems in the presence of randomly pinned particles and apply this\ntheory to supercooled water to validate it. Structural relaxation is mainly\ngoverned by local and non-local activated process. As the pinned fraction\ngrows, a local caging constraint becomes stronger and the long range collective\naspect of relaxation is screened by immobile obstacles. Different responses of\nthe local and cooperative motions results in subtle predictions for how the\nalpha relaxation time varies with pinning and density. Our theoretical analysis\nfor the relaxation time of water with pinned molecules quantitatively well\ndescribe previous simulations. In addition, the thermal dependence of\nrelaxation for unpinned bulk water is also consistent with prior computational\nand experimental data.",
        "positive": "Uniaxial and biaxial soft deformations of nematic elastomers: We give a geometric interpretation of the soft elastic deformation modes of\nnematic elastomers, with explicit examples, for both uniaxial and biaxial\nnematic order. We show the importance of body rotations in this non-classical\nelasticity and how the invariance under rotations of the reference and target\nstates gives soft elasticity (the Golubovic and Lubensky theorem). The role of\nrotations makes the Polar Decomposition Theorem vital for decomposing general\ndeformations into body rotations and symmetric strains. The role of the square\nroots of tensors is discussed in this context and that of finding explicit\nforms for soft deformations (the approach of Olmsted)."
    },
    {
        "anchor": "Localised soft modes and the supercooled liquid's irreversible passage\n  through its configuration space: Using computer simulations, we show that the localized low frequency normal\nmodes of a configuration in a supercooled liquid are strongly correlated with\nthe irreversible structural reorganization of the particles within that\nconfiguration. Establishing this correlation constitutes the identification of\nthe aspect of a configuration that determines the heterogeneity of the\nsubsequent motion. We demonstrate that the spatial distribution of the\nsummation over the soft local modes can persist in spite of particle\nreorganization that produces significant changes in individual modes. Along\nwith spatial localization, the persistent influence of soft modes in particle\nrelaxation results in anisotropy in the displacements of mobile particles over\nthe timescale referred to as beta relaxation.",
        "positive": "A geometric method to determine chromonics' planar anchoring strength: Chromonic nematics are lyotropic liquid crystals that have already been known\nfor half a century, but have only recently raised interest for their potential\napplications in life sciences. Determining elastic constants and anchoring\nstrengths for rigid substrates has thus become a priority in the\ncharacterization of these materials. Here, we present a method to determine\nchromonics' planar anchoring strength. We call it geometric as it is based on\nrecognition and fitting of the stable equilibrium shapes of droplets surrounded\nby the isotropic phase in a thin cell with plates enforcing parallel alignments\nof the nematic director. We apply our method to shapes observed in experiments;\nthey resemble elongated rods with round ends, which are called batonnets. Our\ntheory also predicts other droplets' equilibrium shapes, which are either\nslender and round, called discoids, or slender and pointed, called tactoids. In\nparticular, sufficiently small droplets are expected to display shape\nbistability, with two equilibrium shapes, one tactoid and one discoid,\nexchanging roles as stable and metastable shapes upon varying their common\narea."
    },
    {
        "anchor": "Designing phoretic micro- and nano-swimmers: Small objects can swim by generating around them fields or gradients which in\nturn induce fluid motion past their surface by phoretic surface effects. We\nquantify for arbitrary swimmer shapes and surface patterns, how efficient\nswimming requires both surface ``activity'' to generate the fields, and surface\n``phoretic mobility.'' We show in particular that (i) swimming requires\nsymmetry breaking in either or both of the patterns of \"activity\" and\n``mobility,'' and (ii) for a given geometrical shape and surface pattern, the\nswimming velocity is size-independent. In addition, for given available surface\nproperties, our calculation framework provides a guide for optimizing the\ndesign of swimmers.",
        "positive": "Gel-state nucleation in multilamellar vesicles of\n  dimyristoylphosphatidylcholine and its relation to the critical temperature:\n  A lattice model and microcalorimetry: Differential microcalorimetric measurements have been performed in aqueous\ndispersions of dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles in\na wide range of temperatures covering the whole transition between the lamellar\ngel and lamellar fluid states (the chain-melting/ordering transition). The\nshape of calorimetric curves was analyzed in a temperature range some distance\naway but close to the chain-ordering transition point where small nuclei of gel\n(solid state) are formed. In this range, where the fraction of the \"new-state\"\nlipid is small, the nucleation process can be considered independent of the\ninterlayer interactions and determined mainly by the lateral interactions. The\nsmall-scale nucleation was analyzed in terms of a two-dimensional Ising-like\nlattice model. The gel-fluid contact energy related to the critical temperature\n(in terms of Ising model) was estimated for DMPC studied here and\ndipalmitoylphosphatidylcholine studied earlier. The contact energy was found to\nbe not high enough to provide the discontinuous, first-order character of\ntransition. Therefore, the signs of first-order character observed in the\nvesicles made of these lipids are not due to lateral but rather interlayer\n3D-interactions. The extrapolation to longer lipids shows that the transition\ndiscontinuity inherent to a lipid layer (i.e., determined by the lateral\ninteractions themselves) is expected for the saturated phosphatidylcholines\nhaving more than 16-18 C-atoms per chain. Interestingly, it is the saturated\nchains of this length that are the most abundant in biological membranes.\nProbably, the biological membrane \"prefers\" to be near the critical state where\nthe system is the most responsive to physical actions."
    },
    {
        "anchor": "Disentangling kinetics from thermodynamics in heterogeneous colloidal\n  systems: Nucleation and growth (N&G) - the emergence of a new phase within an\ninitially homogeneous one - is one of the most important physical phenomena by\nwhich gas-liquid, liquid-liquid and solid-liquid phase separation takes place.\nAccordingly, thermodynamics sets the asymptotic boundaries towards which the\nsystem must evolve, while kinetics tries to cope with it by imposing the\ntransport rates at which phase separation is realized. In all heterogeneous\ncolloidal systems observed in nature, the composition, shape, structure and\nultimately physical properties result from the trade-off between thermodynamics\nand kinetics. In this work we demonstrate, by carefully selecting colloidal\nsystems and controlling phase separation in microfluidic devices, that it\nbecomes possible to go beyond N&G, disentangling kinetics effects from\nthermodynamics in composition, structure and physical properties of the final\nsystem. Using amyloid fibril and cellulose nanocrystal filamentous colloids for\nwhich the binodal curve defining the two-phase region in the phase diagram is\ngiven by two separate vertical lines, we extrude a solution set at one\nthermodynamic branch inside the other branch, realizing nematic or cholesteric\ndroplets where the composition is set by thermodynamics, while the structure\nand morphology are defined by dynamic flow parameters. We demonstrate that\ndeparting from the N&G paradigm unveils new physical phenomena, such as orders\nof magnitude shorter timescales, a wider phase diagram and internal cholesteric\nstructures that are not observable via conventional LLPS. We also show that by\nco-dispersing plasmonic gold nanoparticles within colloidal liquid crystalline\ndroplets, our approach enables on-demand fabrication of multicomponent\nheterogeneous liquid crystals, enhancing their potential, and introducing\noriginal fundamental and technological directions in multicomponent structured\nfluids.",
        "positive": "Structuro-elasto-plasticity (StEP) model for plasticity in disordered\n  solids: Elastoplastic lattice models for the response of solids to deformation\ntypically incorporate structure only implicitly via a local yield strain that\nis assigned to each site. However, the local yield strain can change in\nresponse to a nearby or even distant plastic event in the system. This\ninterplay is key to understanding phenomena such as avalanches in which one\nplastic event can trigger another, leading to a cascade of events, but\ntypically is neglected in elastoplastic models. To include the interplay one\ncould calculate the local yield strain for a given particulate system and\nfollow its evolution, but this is expensive and requires knowledge of particle\ninteractions, which is often hard to extract from experiments. Instead, we\nintroduce a structural quantity, \"softness,\" obtained using machine learning to\ncorrelate with imminent plastic rearrangements. We show that softness also\ncorrelates with local yield strain. We incorporate softness to construct a\n\"structuro-elasto-plasticity\" model that reproduces particle simulation results\nquantitatively for several observable quantities, confirming that we capture\nthe influence of the interplay of local structure, plasticity, and elasticity\non material response."
    },
    {
        "anchor": "Multi-shape memory by dynamic elastocapillary self-assembly: Inspired by the synchronized beating of cilia, we show that the collective\ndynamics of hair-like fibers in a meniscus during fast drainage enables their\nself-organization into multiple topologies including complex shape inversions.\nBy draining liquid from triangular-base hair bundles, we demonstrate their\ntransformations into concave hexagons, rounded triangles, circles and inverted\ntriangles. These topologically distinct shapes are quenched collective mode\nshapes of the beating hair each corresponding to specific drainage rates of the\nliquid, and cyclic shape re-transformations can be simply stimulated by\nrepeated immersion and drainage. The various topologies correspond to multiple\nelastocapillary equilibria. Complex cellular materials with varying pore size\nand density can be obtained by changing the drain rates from hair assemblies.\nDue to its simple implementation and energy efficiency, these shape\ntransformations can have applications ranging from three-dimensional\nlithography to smart multi-functional surfaces.",
        "positive": "Chiral Self-Assembly of Helical Particles: The shape of the building blocks plays a crucial role in directing\nself-assembly towards desired architectures. Out of the many different shapes,\nhelix has a unique position. Helical structures are ubiquitous in nature and a\nhelical shape is exhibited by the most important biopolymers like\npolynucleotides, polypeptides and polysaccharides as well as by cellular\norganelles like flagella. Helical particles can self-assemble into chiral\nsuperstructures, which may have a variety of applications, e.g. as photonic\n(meta)materials. However,a clear and definite understanding of these structures\nhas not been entirely achieved yet. We have recently undertaken an extensive\ninvestigation on the phase behaviour of hard helical particles, using numerical\nsimulations and classical density functional theory. Here we present a detailed\nstudy of the phase diagram of hard helices as a function of their morphology.\nThis includes a variety of liquid-crystal phases, with different degrees of\norientational and positional ordering. We show how, by tuning the helix\nparameters, it is possible to control the organization of the system. Starting\nfrom slender helices, whose phase behaviour is similar to that of rodlike\nparticles, the increase in curliness leads to the onset of azimuthal\ncorrelations between the particles and the formation of phases specific to\nhelices. These phases feature a new kind of screw order, of which there is\nexperimental evidence in colloidal suspensions of helical flagella."
    },
    {
        "anchor": "Doped Colloidal Artificial Ice: We examine square and kagome artificial spin ice for colloids confined in\narrays of double-well traps. Unlike magnetic artificial spin ices, colloidal\nand vortex artificial spin ice realizations allow creation of doping sites\nthrough double occupation of individual traps. We find that doping square and\nkagome ice geometries produces opposite effects. For square ice, doping creates\nlocal excitations in the ground state configuration that produce a local\nmelting effect as the temperature is raised. In contrast, the kagome ice ground\nstate can absorb the doping charge without generating non-ground-state\nexcitations, while at elevated temperatures the hopping of individual colloids\nis suppressed near the doping sites. These results indicate that in the square\nice, doping adds degeneracy to the ordered ground state and creates local weak\nspots, while in the kagome ice, which has a highly degenerate ground state,\ndoping locally decreases the degeneracy and creates local hard regions.",
        "positive": "Stiffening solids with liquid inclusions: From bone and wood to concrete and carbon fibre, composites are ubiquitous\nnatural and engineering materials. Eshelby's inclusion theory describes how\nmacroscopic stress fields couple to isolated microscopic inclusions, allowing\nprediction of a composite's bulk mechanical properties from a knowledge of its\nmicrostructure. It has been extended to describe a wide variety of phenomena\nfrom solid fracture to cell adhesion. Here, we show experimentally and\ntheoretically that Eshelby's theory breaks down for small liquid inclusions in\na soft solid. In this limit, an isolated droplet's deformation is strongly\nsize-dependent with the smallest droplets mimicking the behaviour of solid\ninclusions. Furthermore, in opposition to the predictions of conventional\ncomposite theory, we find that finite concentrations of small liquid inclusions\nenhance the stiffness of soft solids. A straight-forward extension of Eshelby's\ntheory, accounting for the surface tension of the solid-liquid interface,\nexplains our experimental observations. The counterintuitive effect of\nliquid-stiffening of solids is expected whenever droplet radii are smaller than\nan elastocapillary length, given by the ratio of the surface tension to Young's\nmodulus of the solid matrix."
    },
    {
        "anchor": "Scaling behavior of knotted random polygons and self-avoiding polygons:\n  Topological swelling with enhanced exponent: We show that the average size of self-avoiding polygons (SAP) with a fixed\nknot is much larger than that of no topological constraint if the excluded\nvolume is small and the number of segments is large. We call it topological\nswelling. We argue an \"enhancement\" of the scaling exponent for random polygons\nwith a fixed knot. We study them systematically through SAP consisting of hard\ncylindrical segments with various different values of the radius of segments.\nHere we mean by the average size the mean-square radius of gyration.\nFurthermore, we show numerically that the equilibrium length of a composite\nknot is given by the sum of those of all constituent prime knots. Here we\ndefine the equilibrium length of a knot by such a number of segments that\ntopological entropic repulsions are balanced with the knot complexity in the\naverage size. The additivity suggests the local knot picture.",
        "positive": "Geometric tuning of self-propulsion for Janus catalytic particles: Catalytic swimmers have attracted much attention as alternatives to\nbiological systems for examining collective microscopic dynamics and the\nresponse to physico-chemical signals. Yet, understanding and predicting even\nthe most fundamental characteristics of their individual propulsion still\nraises important challenges. While chemical asymmetry is widely recognized as\nthe cornerstone of catalytic propulsion, different experimental studies have\nreported that particles with identical chemical properties may propel in\nopposite directions. Here, we show that, beyond its chemical properties, the\ndetailed shape of a catalytic swimmer plays an essential role in determining\nits direction of motion, demonstrating the compatibility of the classical\ntheoretical framework with experimental observations."
    },
    {
        "anchor": "Dynamics of Fluctuating Thin Sheets Under Random Forcing: We study the dynamic structure factor of fluctuating elastic thin sheets\nsubject to conservative (athermal) random forcing. In Steinbock, Katzav &\nBoudaoud, Phys. Rev. Research 4, 033096 (2022), the static structure factor of\nsuch a sheet was studied. In this paper, we recap the model developed there and\ninvestigate its dynamic properties. Using the self-consistent expansion (SCE),\nthe time dependent two-point function of the height profile is determined and\nfound to decay exponentially in time. Despite strong nonlinear coupling, the\ndecay rate of the dynamic structure factor is found to coincide with the\neffective coupling constant for the static properties which suggests that the\nmodel under investigation exhibits certain quasi-linear behaviour. Confirmation\nof these results by numerical simulations is also presented.",
        "positive": "Formation of adhesion domains in stressed and confined membranes: The adhesion bonds connecting a lipid bilayer to an underlying surface may\nundergo a condensation transition resulting from an interplay between a short\nrange attractive potential between them, and a long range fluctuation-induced\npotential of mean force. Here, we use computer simulations of a coarse-grained\nmolecular model of supported lipid bilayers to study this transition in\nconfined membranes, and in membranes subjected to a non-vanishing surface\ntension. Our results show that confinement may alter significantly the\ncondensation transition of the adhesion bonds, whereas the application of\nsurface tension has a very minor effect on it. We also investigate domain\nformation in membranes under negative tension which, in free membranes, causes\nenhancement of the amplitude of the membrane thermal undulations. Our results\nindicate that in supported membranes, this effect of a negative surface tension\non the fluctuation spectrum is largely eliminated by the pressure resulting\nfrom the mixing entropy of the adhesion bonds."
    },
    {
        "anchor": "One-dimensional fluids with second nearest-neighbor interactions: As is well known, one-dimensional systems with interactions restricted to\nfirst nearest neighbors admit a full analytically exact statistical-mechanical\nsolution. This is essentially due to the fact that the knowledge of the first\nnearest-neighbor probability distribution function, $p_1(r)$, is enough to\ndetermine the structural and thermodynamic properties of the system. On the\nother hand, if the interaction between second nearest-neighbor particles is\nturned on, the analytically exact solution is lost. Not only the knowledge of\n$p_1(r)$ is not sufficient anymore, but even its determination becomes a\ncomplex many-body problem. In this work we systematically explore different\napproximate solutions for one-dimensional second nearest-neighbor fluid models.\nWe apply those approximations to the square-well and the attractive two-step\npair potentials and compare them with Monte Carlo simulations, finding an\nexcellent agreement.",
        "positive": "Elasticity of Interfacial Rafts of Hard Particles with Soft Shells: We study an elasticity model for compressed protein monolayers or particle\nrafts at a liquid interface. Based on the microscopic view of hard-core\nparticles with soft shells, a bead-spring model is formulated and analyzed in\nterms of continuum elasticity theory. The theory can be applied, for example,\nto hydrophobin-coated air-water interfaces or, more generally, to liquid\ninterfaces coated with an adsorbed monolayer of interacting hard-core\nparticles. We derive constitutive relations for such particle rafts and\ndescribe the buckling of compressed planar liquid interfaces as well as their\napparent Poisson ratio. We also use the constitutive relations to obtain shape\nequations for pendant or buoyant capsules attached to a capillary, and to\ncompute deflated shapes of such capsules. A comparison with capsules obeying\nthe usual Hookean elasticity (without hard cores) reveals that the hard cores\ntrigger capsule wrinkling. Furthermore, it is shown that a shape analysis of\ndeflated capsules with hard-core/soft-shell elasticity gives apparent elastic\nmoduli which can be much higher than the original values if Hookean elasticity\nis assumed."
    },
    {
        "anchor": "Fast and Adjustable Resolution Grazing Incidence x-ray Liquid Surfaces\n  Diffraction achieved through 2D Detector: We developed a setup using a two dimensional camera for Grazing Incidence\nx-ray Diffraction (GIXD) on Langmuir monolayers and more generally for surface\ndiffraction on two dimensional powders. Compared to the classical setup using a\nlinear detector combined with Soller's slits, the acquisition time is reduced\nof a factor of at least 10 (from more than one hour to a few minutes) using the\nsame x-ray source (synchrotron bending magnet) with a comparable signal to\nnoise ratio. Moreover, using an horizontal gap slit, the experimental\nresolution can be adjusted and for small values of the gap, better resolution\ncan be achieved compared to the one obtained with the linear detector.",
        "positive": "Can the frequency-dependent specific heat be measured by thermal\n  effusion methods?: It has recently been shown that plane-plate heat effusion methods devised for\nwide-frequency specific-heat spectroscopy do not give the isobaric specific\nheat, but rather the so-called longitudinal specific heat. Here it is shown\nthat heat effusion in a spherical symmetric geometry also involves the\nlongitudinal specific heat."
    },
    {
        "anchor": "Theoretical Prediction and experimental measurement of the mixed\n  flocculation/coalescence rate of ionic Hexadecane-in-water nano-emulsions: Theoretical calculations of the mixed aggregation/coalescence (kFC) rate\ncorresponding to a set of hexadecane-in-water nano-emulsions stabilized with\nsodium dodecyl sulphate (SDS) at different NaCl concentrations are presented.\nThe rates were obtained through the change of the total number of aggregates of\nthe dispersions as a function of time, predicted by Emulsion Stability\nSimulation (ESS). Two different models were implemented in order to mimic the\ndependence of the surface excess of the surfactant on the salt concentration.\nExperimental measurements of kFC were also made, based on the change of the\nturbidity of the emulsions as a function of time. A satisfactory agreement\nbetween theory and experiment is only attained if the model of surfactant\nadsorption accounts for the balance between the salting out of the surfactant\nsolution and the partial screening of the surface charge of the drops induced\nby the increase of the ionic strength of the continuous phase. The observed\nbehavior cannot be justified on the grounds of the\nDerjaguin-Landau-Verwey-Overbeek (DLVO) theory. Instead, the reversible\nflocculation of the aggregates of any size is proposed as an alternative\nmechanism to explain the dependence of kFC as a function of the salt\nconcentration.",
        "positive": "Physics of Econophysics: Econophysics is a new area developed recently by the cooperation between\neconomists, mathematicians and physicists. It's not a tool to predict future\nprices of stocks and exchange rates. It applies idea, method and models in\nStatistical Physics and Complexity to analyze data from economical phenomena.\nIn this paper, three examples from three active main topics in Econophysics are\npresented first. Then using these examples, we analyze the role of Physics in\nEconophysics. Some comments and emphasis on Physics of Econophysics are\nincluded. New idea of network analysis for economy systems is proposed, while\nthe actual analysis is still in progress."
    },
    {
        "anchor": "Spontaneous trail formation in populations of auto-chemotactic walkers: We study the formation of trails in populations of self-propelled agents that\nmake oriented deposits of pheromones and also sense such deposits to which they\nthen respond with gradual changes of their direction of motion. Based on\nextensive off-lattice computer simulations aiming at the scale of insects,\ne.g., ants, we identify a number of emerging stationary patterns and obtain\nqualitatively the non-equilibrium state diagram of the model, spanned by the\nstrength of the agent--pheromone interaction and the number density of the\npopulation. In particular, we demonstrate the spontaneous formation of\npersistent, macroscopic trails, and highlight some behaviour that is consistent\nwith a dynamic phase transition. This includes a characterisation of the mass\nof system-spanning trails as a potential order parameter. We also propose a\ndynamic model for a few macroscopic observables, including the sub-population\nsize of trail-following agents, which captures the early phase of trail\nformation.",
        "positive": "Concise theory of chiral lipid membranes: A theory of chiral lipid membranes is proposed on the basis of a concise free\nenergy density which includes the contributions of the bending and the surface\ntension of membranes, as well as the chirality and orientational variation of\ntilting molecules. This theory is consistent with the previous experiments\n[J.M. Schnur \\textit{et al.}, Science \\textbf{264}, 945 (1994); M.S. Spector\n\\textit{et al.}, Langmuir \\textbf{14}, 3493 (1998); Y. Zhao, \\textit{et al.},\nProc. Natl. Acad. Sci. USA \\textbf{102}, 7438 (2005)] on self-assembled chiral\nlipid membranes of DC$_{8,9}$PC. A torus with the ratio between its two\ngenerated radii larger than $\\sqrt{2}$ is predicted from the Euler-Lagrange\nequations. It is found that tubules with helically modulated tilting state are\nnot admitted by the Euler-Lagrange equations, and that they are less\nenergetically favorable than helical ripples in tubules. The pitch angles of\nhelical ripples are theoretically estimated to be about 0$^\\circ$ and\n35$^\\circ$, which are close to the most frequent values 5$^\\circ$ and\n28$^\\circ$ observed in the experiment [N. Mahajan \\textit{et al.}, Langmuir\n\\textbf{22}, 1973 (2006)]. Additionally, the present theory can explain twisted\nribbons of achiral cationic amphiphiles interacting with chiral tartrate\ncounterions. The ratio between the width and pitch of twisted ribbons is\npredicted to be proportional to the relative concentration difference of left-\nand right-handed enantiomers in the low relative concentration difference\nregion, which is in good agreement with the experiment [R. Oda \\textit{et al.},\nNature (London) \\textbf{399}, 566 (1999)]."
    },
    {
        "anchor": "Instabilities in elastomers and soft tissues: Biological soft tissues exhibit elastic properties which can be dramatically\ndifferent from rubber-type materials (elastomers). To gain a better\nunderstanding of the role of constitutive relationships in determining material\nresponses under loads we compare three different types of instabilities (two in\ncompression, one in extension) in hyperelasticity for various forms of strain\nenergy functions typically used for elastomers and for soft tissues.\nSurprisingly, we find that the strain-hardening property of soft tissues does\nnot always stabilize the material. In particular we show that the stability\nanalyses for a compressed half-space and for a compressed spherical thick shell\ncan lead to opposite conclusions: a soft tissue material is more stable than an\nelastomer in the former case and less stable in the latter case.",
        "positive": "Emerging contact force heterogeneity in ordered soft granular media: Under external perturbations, inter-particle forces in disordered granular\nmedia are well known to form a heterogeneous distribution with filamentary\npatterns. Better understanding these forces and the distribution is important\nfor predicting the collective behavior of granular media, the media second only\nto water as the most manipulated material in global industry. However, studies\nin this regard so far have been largely confined to granular media exhibiting\nonly geometric heterogeneity, leaving the dimension of mechanical heterogeneity\na rather uncharted area. Here, through a FEM contact mechanics model, we show\nthat a heterogeneous inter-particle force distribution can also emerge from the\ndimension of mechanical heterogeneity alone. Specifically, we numerically study\ninter-particle forces in packing of mechanically heterogeneous disks arranged\nover either a square or a hexagonal lattice and under quasi-static isotropic\ncompression. Our results show that, a hexagonal packing exhibit a more\nheterogeneous inter-particle force distribution than a square packing does. For\nboth packing lattices, preliminary analysis shows the consistent coexistence of\noutliers (i.e., softer disks sustaining larger forces while stiffer disks\nsustaining smaller forces) in comparison to their homogeneous counterparts,\nwhich implies the existence of nonlocal effect. Further analysis on the portion\nof outliers and on spatial contact force correlations suggest that the\nhexagonal packing shows more pronounced nonlocal effect over the square packing\nunder small mechanical heterogeneity. However, such trend is reversed when\nassemblies becomes more mechanically heterogeneous. Lastly, we confirm that, in\nthe absence of particle reorganization events, contact friction merely plays\nthe role of packing stabilization while its variation has little effect on\ninter-particle forces and their distribution."
    },
    {
        "anchor": "The melting of the classical two dimensional Wigner crystal: We report an extensive Monte-Carlo study of the melting of the classical two\ndimensional Wigner crystal for a system of point particles interacting via the\n$1/r$-Coulomb potential. A hexatic phase is found in systems large enough. With\nthe multiple histograms method and the finite size scaling theory, we show that\nthe fluid/hexatic phase transition is weakly first order. No set of critical\nexponents, consistent with a Kosterlitz-Thouless transition and the finite size\nscaling analysis for this transition, have been found.",
        "positive": "Thermotaxis of Janus Particles: The interactions of autonomous microswimmers play an important role for the\nformation of collective states of motile active matter. We study them in detail\nfor the common microswimmer-design of two-faced Janus spheres with hemispheres\nmade from different materials. Their chemical and physical surface properties\nmay be tailored to fine-tune their mutual attractive, repulsive or aligning\nbehavior. To investigate these effects systematically, we monitor the dynamics\nof a single gold-capped Janus particle in the external temperature field\ncreated by an optically heated metal nanoparticle. We quantify the\norientation-dependent repulsion and alignment of the Janus particle and explain\nit in terms of a simple theoretical model for the induced thermoosmotic surface\nfluxes. The model reveals that the particle's angular velocity is solely\ndetermined by the temperature profile on the equator between the Janus\nparticle's hemispehres and their phoretic mobility contrast. The distortion of\nthe external temperature field by their heterogeneous heat conductivity is\nmoreover shown to break the apparent symmetry of the problem."
    },
    {
        "anchor": "Experiment and Modeling of Rice Winnowing: Granular Segregation Method\n  in Ancient Traditions: Rice winnowing is a process of separation of small and large rice grains by\nair flow practiced since the ancient human history especially in societies\nwhere rice is the main source of carbohydrate (in Asia, Africa, and Latin\nAmerica). Indeed, this process contains rich of scientific rule but has never\nbeen documented by the old society. We report here experimental investigation\nof the rice winnowing and develop a physical model to explain the process of\nsegregation of rice grains having different size or density. Flapping the tray\nin the winnowing process, generates a vortex centered at position around the\ntray free end. We demonstrated numerically that the effectiveness of\nsegregation is strongly depended on the different in grain sizes (for grain\nfrom the same material), the initial position of the grain, and the angular\nvelocity of the vortex generated by flapping the tray. We obtained a phase\ndiagram describing different final conditions of winnowing process (either the\nsmall grains move towards the tray fee end or move toward the inner end of the\ntray, able or unable to leave the tray at the free end). The result can be\nuseful to design a new method in separating grains based on size or density.",
        "positive": "Explosive rigidity percolation in kirigami: Controlling the connectivity and rigidity of kirigami, i.e. the process of\ncutting paper to deploy it into an articulated system, is critical in the\nmanifestations of kirigami in art, science and technology, as it provides the\nresulting metamaterial with a range of mechanical and geometric properties.\nHere we combine deterministic and stochastic approaches for the control of\nrigidity in kirigami using the power of $k$ choices, an approach borrowed from\nthe statistical mechanics of explosive percolation transitions. We show that\nseveral methods for rigidifying a kirigami system by incrementally changing\neither the connectivity or the rigidity of individual components allow us to\ncontrol the nature of the explosive transition by a choice of selection rules.\nOur results suggest simple lessons for the design and control of mechanical\nmetamaterials."
    },
    {
        "anchor": "Statistical Properties of a Polymer Globule Formed during Collapse with\n  the Irreversible Coalescence of Units: Collapse of the polymer chain upon the sharp decrease of solvent quality is\nstudied. During collapse, any pair of polymer units appearing in a sufficiently\nclose vicinity in space has the possibility with a certain probability to form\nan irreversible crosslink, thereby preventing the interpenetration of chain\nmaterial between the forming clusters. Globular structures having different\nspatial chain packing at various scales are obtained by computer simulations.\nIt is shown that the dependence of probability of contact between two monomers\nin space , where s is a distance between monomers along chain, reproduces a\nnumber of characteristic features observed previously in experiments on the\nanalysis of three-dimensional chromatin packing. The cluster analysis of\nintramolecular contact maps makes it possible to express the hypothesis that\nthere are characteristic discrete hierarchical levels in polymer packing\nassociated with the number-theoretic origin of rare-event statistics and\ninherent to individual maps of intra- and interchromosomal contacts.",
        "positive": "Gibbs adsorption impact on a nanodroplet shape: modification of\n  Young-Laplace equation: An efficient technique for the evaluation of the Gibbs adsorption of a liquid\non a solid substrate is presented. The behavior of a water nanodroplet on a\nsilicon surface is simulated with molecular dynamics. An external field with\nvarying strength is applied on the system to tune the solid-liquid interfacial\ncontact area. A linear dependence of droplet's volume on the contact area is\nobserved. Our modified Young--Laplace equation is used to explain the influence\nof the Gibbs adsorption on the nanodroplet volume contraction. Fitting of the\nmolecular dynamics results with these of an analytical approach allows us to\nevaluate the number of atoms per unit area adsorbed on the substrate, which\nquantifies the Gibbs adsorption. Thus, a threshold of a droplet size is\nobtained, for which the impact of the adsorption is crucial. Moreover, the\npresented results can be applied for the evaluation of the adsorption impact on\nthe physical--chemical properties of systems with important surface-to-volume\nfraction."
    },
    {
        "anchor": "Topological Forces in a Model System for Reptation Dynamics: We construct a micromechanical version of an early model for topologically\nconstrained polymers -- a 2D chain amongst point-like uncrossable obstacles --\nwhich allows us to explicitly elucidate the role of topological forces beyond\nconfining the chain to a curvilinear tube-like path. Our simulations reveal\nthat linear relaxation of the contour length \\textit{along the tube} is slowed\ndown by the presence of topological forces that can be considered as additional\neffective topological ``friction'' in quiescence. However, this perspective\nfails in predicting the strong forces that resist the imposed curvilinear\nmotion of the chain during nonlinear startup microrheology. These entropic\nforces are nonlocal in nature and result from an unexpected coupling between\norientational and longitudinal dynamics.",
        "positive": "Jamming III: Characterizing Randomness via the Entropy of Jammed Matter: The nature of randomness in disordered packings of frictional and\nfrictionless spheres is investigated using theory and simulations of identical\nspherical grains. The entropy of the packings is defined through the force and\nvolume ensemble of jammed matter and shown difficult to calculate analytically.\nA mesoscopic ensemble of isostatic states is then utilized in an effort to\npredict the entropy through the defnition of a volume function dependent on the\ncoordination number. Equations of state are obtained relating entropy, volume\nfraction and compactivity characterizing the different states of jammed matter,\nand elucidating the phase diagram for jammed granular matter. Analytical\ncalculations are compared to numerical simulations using volume fluctuation\nanalysis and graph theoretical methods, with reasonable agreement. The entropy\nof the jammed system reveals that the random loose packings are more disordered\nthan random close packings, allowing for an unambiguous interpretation of both\nlimits. Ensemble calculations show that the entropy vanishes at random close\npacking (RCP), while numerical simulations show that a finite entropy remains\nin the microscopic states at RCP. The notion of a negative compactivity, that\nexplores states with volume fractions below those achievable by existing\nsimulation protocols, is also explored, expanding the equations of state. We\ndiscuss possible extensions to the present mesoscopic approach describing\npackings from RLP to RCP to the ordered branch of the equation of state in an\neffort to understand the entropy of jammed matter in the full range of\ndensities from RLP to FCC."
    },
    {
        "anchor": "Dynamics and stress in gravity driven granular flow: We study, using simulations, the steady-state flow of dry sand driven by\ngravity in two-dimensions. An investigation of the microscopic grain dynamics\nreveals that grains remain separated but with a power-law distribution of\ndistances and times between collisions.\n  While there are large random grain velocities, many of these fluctuations are\ncorrelated across the system and local rearrangements are very slow. Stresses\nin the system are almost entirely transfered by collisions and the structure of\nthe stress tensor comes almost entirely from a bias in the directions in which\ncollisions occur.",
        "positive": "A Thermal Discrete Element Analysis of EU Solid Breeder Blanket\n  subjected to Neutron Irradiation: Due to neutron irradiation, solid breeder blankets are subjected to complex\nthermo-mechanical conditions. Within one breeder unit, the ceramic breeder bed\nis composed of spherical-shaped lithium orthosilicate pebbles, and as a type of\ngranular material, it exhibits strong coupling between temperature and stress\nfields. In this paper, we study these thermo-mechanical problems by developing\na thermal discrete element method (Thermal-DEM). This proposed simulation tool\nmodels each individual ceramic pebble as one element and considers grain-scale\nthermo-mechanical interactions between elements. A small section of solid\nbreeder pebble bed in HCPB is modelled using thousands of individual pebbles\nand subjected to volumetric heating profiles calculated from neutronics under\nITER-relevant conditions. We consider heat transfer at the grain-scale between\npebbles through both solid-to-solid contacts and the interstitial gas phase,\nand we calculate stresses arising from thermal expansion of pebbles. The\noverall effective conductivity of the bed depends on the resulting compressive\nstress state during the neutronic heating. The thermal-DEM method proposed in\nthis study provides the access to the grain-scale information, which is\nbeneficial for HCPB design and breeder material optimization, and a better\nunderstanding of overall thermo-mechanical responses of the breeder units under\nfusion-relevant conditions."
    },
    {
        "anchor": "Drying Pathways of an Evaporating Soft Matter Droplet: Micro-droplets of soft matter solutions have different morphologies upon\ndrying, and can finally become wrinkled, buckled or cavitated particles. We\ninvestigate the morphology evolution of a drying soft matter droplet in this\nwork: at the early stage of drying, wrinkling or cavitation instability can\noccur in the droplet, depending on the comparison between the critical\nwrinkling and cavitation pressure; at a later stage of drying, no wrinkle will\nappear if cavitation happens first, while there can still be cavitation if\nwrinkling happens first. A three-dimensional phase diagram in the space of\nelastic length, gel layer thickness and weight loss is provided for\nillustrating these drying pathways of a soft matter droplet, which can guide\nfuture fabrications of micro-particles with desired morphologies.",
        "positive": "Phase Behavior of Columnar DNA Assemblies: The pair interaction between two stiff parallel linear DNA molecules depends\nnot only on the distance between their axes but on their azimuthal orientation.\nThe positional and orientational order in columnar B-DNA assemblies in solution\nis investigated, based on the DNA-DNA electrostatic pair potential that takes\ninto account DNA helical symmetry and the amount and distribution of adsorbed\ncounterions. A phase diagram obtained by lattice sum calculations predicts a\nvariety of positionally and azimuthally ordered phases and bundling transitions\nstrongly depending on the counterion adsorption patterns."
    },
    {
        "anchor": "Translocation time of a polymer chain through an energy gradient\n  nanopore: The translocation time of a polymer chain through an interaction energy\ngradient nanopore was studied by Monte Carlo simulations and the Fokker-Planck\nequation with double-absorbing boundary conditions. Both the simulation and\ncalculation revealed three different behaviors for polymer translocation. These\nbehaviors can be explained qualitatively from free-energy landscapes obtained\nfor polymer translocation at different parameters. Results show that the\ntranslocation time of a polymer chain through a nanopore can be tuned by\nsuitably designing the interaction energy gradient.",
        "positive": "Stress in frictionless granular material: Adaptive Network Simulations: We present a minimalistic approach to simulations of force transmission\nthrough granular systems. We start from a configuration containing cohesive\n(tensile) contact forces and use an adaptive procedure to find the stable\nconfiguration with no tensile contact forces. The procedure works by\nsequentially removing and adding individual contacts between adjacent beads,\nwhile the bead positions are not modified. In a series of two-dimensional\nrealizations, the resulting force networks are shown to satisfy a linear\n  constraint among the three components of average stress, as anticipated by\nrecent theories. The coefficients in the linear constraint remain nearly\n  constant for a range of shear loadings up to about .6 of the normal loading.\nThe spatial distribution of contact forces shows strong concentration along\n``force chains\". The probability of contact forces of magnitude f shows an\nexponential falloff with f. The response to a local perturbing force is\nconcentrated along two characteristic rays directed downward and laterally."
    },
    {
        "anchor": "Role of metallic core for the stability of virus-like particles in\n  strongly coupled electrostatics: We investigate the osmotic (electrostatic) pressure acting on the\nproteinaceous shell of a generic model of virus-like particles (VLPs),\ncomprising a charged outer shell and a metallic nanoparticle core, coated by a\ncharged layer and bathed in an aqueous electrolyte (salt) solution. Motivated\nby the recent studies accentuating the role of multivalent ions for the\nstability of VLPs, we focus on the effects of multivalent cations and anions in\nan otherwise monovalent ionic bathing solution. We perform extensive\nMonte-Carlo simulations based on appropriate Coulombic interactions that\nconsistently take into account the effects of salt screening, the dielectric\npolarization of the metallic core, and the strong-coupling electrostatics due\nto the presence of multivalent ions. We specifically study the intricate roles\nthese factors play in the electrostatic stability of the model VLPs. It is\nshown that while the insertion of a metallic nanoparticle by itself can produce\nnegative, inward-directed, pressure on the outer shell, addition of only a\nsmall amount of multivalent counterions can robustly engender negative\npressures, enhancing the VLP stability across a wide range of values for the\nsystem parameters.",
        "positive": "Discontinuous Shear Thickening in Brownian Suspensions By Dynamic\n  Simulation: Dynamic particle-scale numerical simulations are used to show that the shear\nthickening observed in dense colloidal, or Brownian, suspensions is of a\nsimilar nature to that observed in non-colloidal suspensions, i.e., a\nstress-induced transition from a flow of lubricated near-contacting particles\nto a flow of a frictionally contacting network of particles. Abrupt (or\ndiscontinuous) shear thickening is found to be a geometric rather than\nhydrodynamic phenomenon; it stems from the strong sensitivity of the jamming\nvolume fraction to the nature of contact forces between suspended particles.\nThe thickening obtained in a colloidal suspension of purely hard frictional\nspheres is qualitatively similar to experimental observations. However, the\nagreement cannot be made quantitative with only hydrodynamics, frictional\ncontacts and Brownian forces. Therefore the role of a short-range repulsive\npotential mimicking the stabilization of actual suspensions on the thickening\nis studied. The effects of Brownian and repulsive forces on the onset stress\ncan be combined in an additive manner. The simulations including Brownian and\nstabilizing forces show excellent agreement with experimental data for the\nviscosity $\\eta$ and the second normal stress difference $N_2$."
    },
    {
        "anchor": "Modification of the aging dynamics of glassy polymers due to a\n  temperature step: Molecular dynamics simulations are used to investigate the connection between\nthermal history and physical aging in polymer glasses, in particular the\neffects of a temperature square step. Measurements of two-time correlation\nfunctions show that a negative temperature step causes \"rejuvenation\" of the\nsample: the entire spectrum of relaxation times appears identical to a younger\nspecimen that did not experience a temperature step. A positive temperature\nstep, however, leads to significant changes in the relaxation times. At short\ntimes, the dynamics are accelerated (rejuvenation), whereas at long times the\ndynamics are slowed (over-aging). All findings are in excellent qualitative\nagreement with recent experiments. The two regimes can be explained by the\ncompeting contributions of dynamical heterogeneities and faster aging dynamics\nat higher temperatures. As a result of this competition, the transition between\nrejuvenation and over-aging depends on the length of the square step, with\nshorter steps causing more rejuvenation and longer steps causing more\nover-aging. Although the spectrum of relaxation times is greatly modified by a\ntemperature step, the van Hove functions, which measure the distribution of\nparticle displacements, exhibit complete superposition at times when the\nmean-squared displacements are equal.",
        "positive": "Rheological basis of skeletal muscle work loops: Skeletal muscle is subjected to simultaneous time-varying neural stimuli and\nlength changes in vivo. Work loops are experimental representations of these in\nvivo conditions and exhibit force versus length responses that are not\nexplainable using either soft matter rheology or the classical isometric and\nisotonic characterizations of muscle. These gaps in our understanding have\noften prompted the search for new muscle phenomena. However, we presently lack\na framework to explain the mechanical origins of work loops that integrates\nmultiple facets of current understanding of muscle, as a rheological material\nand also a stimulus-responsive actuator. Here we present a new hypothesis that\nwork loops emerge by splicing together force versus length loops corresponding\nto different constant stimuli. Using published muscle datasets and a detailed\nsarcomere model, we find that the hypothesis accurately predicts work loops and\nhelps understand them in terms of rheological behaviors measured at\nfixed-stimuli. Importantly, this framework identifies conditions under which a\nrheological understanding of muscle fails to explain the emergent work loops,\nand new muscle phenomena may be necessary to explain its in vivo function."
    },
    {
        "anchor": "Cooling rate, heating rate and aging effects in glassy water: We report a molecular dynamics simulation study of the properties of the\npotential energy landscape sampled by a system of water molecules during the\nprocess of generating a glass by cooling, and during the process of\nregenerating the equilibrium liquid by heating the glass. We study the\ndependence of these processes on the cooling/heating rates as well as on the\nrole of aging (the time elapsed in the glass state). We compare the properties\nof the potential energy landscape sampled during these processes with the\ncorresponding properties sampled in the liquid equilibrium state to elucidate\nunder which conditions glass configurations can be associated with equilibrium\nliquid configurations.",
        "positive": "Self-assembly of Microcapsules via Colloidal Bond Hybridization and\n  Anisotropy: Particles with directional interactions are promising building blocks for new\nfunctional materials and may serve as models for biological structures.\nMutually attractive nanoparticles that are deformable due to flexible surface\ngroups, for example, may spontaneously order themselves into strings, sheets\nand large vesicles. Furthermore, anisotropic colloids with attractive patches\ncan self-assemble into open lattices and colloidal equivalents of molecules and\nmicelles. However, model systems that combine mutual attraction, anisotropy,\nand deformability have---to the best of our knowledge---not been realized.\nHere, we synthesize colloidal particles that combine these three\ncharacteristics and obtain self-assembled microcapsules. We propose that mutual\nattraction and deformability induce directional interactions via colloidal bond\nhybridization. Our particles contain both mutually attractive and repulsive\nsurface groups that are flexible. Analogous to the simplest chemical bond,\nwhere two isotropic orbitals hybridize into the molecular orbital of H2, these\nflexible groups redistribute upon binding. Via colloidal bond hybridization,\nisotropic spheres self-assemble into planar monolayers, while anisotropic\nsnowman-like particles self-assemble into hollow monolayer microcapsules. A\nmodest change of the building blocks thus results in a significant leap in the\ncomplexity of the self-assembled structures. In other words, these relatively\nsimple building blocks self-assemble into dramatically more complex structures\nthan similar particles that are isotropic or non-deformable."
    },
    {
        "anchor": "A novel anomalous region of water: Water is the most important liquid in the Universe. At the same time it is\nthe most anomalous liquid. It demonstrates several dozens of anomalies, among\nwhich are density anomaly, diffusion anomaly etc. Anomalous behavior of water\nis a topic numerous publications. However, most of the publications investigate\nthe anomalous behavior of water in the vicinity of critical points: the\nliquid-gas critical point and the second hypothetical critical point in\nsupercooled region. Here we analyze experimental data on such properties of\nwater as heat capacity, speed of sound, dynamic viscosity and thermal\nconductivity. We show that these properties demonstrate anomalous maxima and\nminima in a region which is far from both critical points. Therefore, we find a\nnovel region of anomalous properties of water (anomalous triangle) which cannot\nbe related to critical fluctuations. We also perform a molecular dynamics\nsimulations of this region with two common water models - SPC/E and TIP4P - and\nshow that these models fail to describe the novel anomalous region.",
        "positive": "Microstructure, Surface Plasmon, Magneto-optic Surface Plasmon, and\n  Sensitivity Properties of Magneto-plasmonic Co/Au Multilayers: Microstructure properties of Co/Au multilayers prepared using dc-magnetron\nsputtering is reported using X-ray reflectivity (XRR) and X-ray diffraction\n(XRD) analysis. XRR profiles of these multilayers showed excellent bilayer\nperiodicity. The XRD spectra displayed Co layer thickness-dependent properties.\nHowever, annealing increased lateral tensile strain decreased compressive\nstrain along the normal substrate direction. While surface roughness,\ncrystallite grain size, and strain are affected by Co layer thickness,\nmicrostructure and periodicity are dominated by fcc-Au (111). Surface plasmon\nresonance (SPR) and magneto-optic SPR study of an optimized Co/Au multilayer in\nKretschmann configuration for air-He and water-Methanol media showed an\nenhanced sensitivity by over 4 times when excited at the wavelength of 785 nm\nas compared to the conventional SPR configuration when excited at the\nwavelength of 632.8 nm. This enhancement in MOSPR sensitivity means the\ndetection limit of this class of transducers can be substantially improved by\ntuning Co/Au layer thickness, wavelength, and incident angle of optical\nradiation."
    },
    {
        "anchor": "Like-charge attraction through hydrodynamic interaction: We demonstrate that the attractive interaction measured between like-charged\ncolloidal spheres near a wall can be accounted for by a nonequilibrium\nhydrodynamic effect. We present both analytical results and Brownian dynamics\nsimulations which quantitatively capture the one-wall experiments of Larsen and\nGrier (Nature 385, p. 230, 1997).",
        "positive": "The effect of an exterior electric field on the instability of\n  dielectric plates: We investigate the theoretical nonlinear response, Hessian stability, and\npossible wrinkling behaviour of a voltage-activated dielectric plate immersed\nin a tank filled with silicone oil. Fixed rigid electrodes are placed on the\ntop and bottom of the tank, and an electric field is generated by a potential\ndifference between the electrodes. We solve the associated incremental boundary\nvalue problem of superimposed, inhomogeneous small-amplitude wrinkles,\nsignalling the onset of instability. We decouple the resulting bifurcation\nequation into symmetric and antisymmetric modes. For a neo-Hookean dielectric\nplate, we show that a potential difference between the electrodes can induce a\nthinning of the plate and thus an increase of its planar area, similar to the\nscenarios encountered when there is no silicone oil. However, we also find\nthat, depending on the material and geometric parameters, an increasing applied\nvoltage can also lead to a thickening of the plate, and thus a shrinking of its\narea. In that scenario, Hessian instability and wrinkling bifurcation may then\noccur spontaneously once some critical voltages are reached."
    },
    {
        "anchor": "On Micropolar Elastic Foundations: The modelling of heterogeneous and architected materials poses a significant\nchallenge, demanding advanced homogenisation techniques. However, the\ncomplexity of this task can be considerably simplified through the application\nof micropolar elasticity. Conversely, elastic foundation theory is widely\nemployed in fracture mechanics and the analysis of delamination propagation in\ncomposite materials. This study aims to amalgamate these two frameworks,\nenhancing the elastic foundation theory to accommodate materials exhibiting\nmicropolar behaviour. Specifically, we present a novel theory of elastic\nfoundation for micropolar materials, employing stress potentials formulation\nand a unique normalisation approach. Closed-form solutions are derived for\nstress and couple stress reactions inherent in such materials, along with the\nassociated restoring stiffness. The validity of the proposed theory is\nestablished through verification using the double cantilever beam\nconfiguration. Concluding our study, we elucidate the benefits and limitations\nof the developed theory by quantifying the derived parameters for materials\nknown to exhibit micropolar behaviour. This integration of micropolar\nelasticity into the elastic foundation theory not only enhances our\nunderstanding of material responses but also provides a versatile framework for\nthe analysis of heterogeneous materials in various engineering applications.",
        "positive": "Shock Wave Structure in a Strongly Nonlinear Granular Lattice with\n  Viscous Dissipation: The shock wave structure in a one-dimensional lattice (e.g. granular chain)\nwith a power law dependence of force on displacement between particles with\nviscous dissipation is considered and compared to the corresponding long wave\napproximation. A dissipative term depending on the relative velocity between\nneighboring particles is included in the discrete model to investigate its\ninfluence on the shape of steady shock profiles. The critical viscosity\ncoefficient is obtained from the long-wave approximation for arbitrary values\nof the exponent n and denotes the transition from an oscillatory to a monotonic\nshock profile in stronly nonlinear systems. The expression for the critical\nviscosity coefficient converges to the known equation for the critical\nviscosity in the weakly nonlinear case. Values of viscosity based on this\nexpression are comparable to the values obtained in the numerical analysis of a\ndiscrete particle lattice with a Herzian contact interaction corresponding to n\n= 3/2. An initial disturbance in a discrete system approaches a stationary\nshock profile after traveling a short distance that is comparable to the width\nof the leading pulse of a stationary shock front. The shock front width is\nminimized when the viscosity is equal to its critical value."
    },
    {
        "anchor": "Undulation instability of lipid membranes under an electric field: The influence of an electric field on a poorly conductive membrane such as a\nlipid bilayer is studied theoretically. The unbalanced electric stress created\nby an ionic current across a non-perfectly flat membrane gives rise to a\ndestabilizing surface energy enhancing undulations. The deformation of a\nmembrane attached to a frame and the subsequent force on the frame are derived\nand the electrohydrodynamic instability of a free floating membrane is also\nstudied. We find a most unstable mode of undulation, of wavelength in the $\\mu\nm$ range, connected to the crossover between membrane and solvent dominated\ndissipations.",
        "positive": "Force Dynamics in Weakly Vibrated Granular Packings: The oscillatory force F_b^ac on the bottom of a rigid, vertically vibrated,\ngrain filled column, reveals rich granular dynamics, even when the peak\nacceleration of the vibrations is signicantly less than the gravitational\nacceleration at the earth's surface. For loose packings or high frequencies,\nF_b^ac 's dynamics are dominated by grain motion. For moderate driving\nconditions in more compact samples, grain motion is virtually absent, but\nF_b^ac nevertheless exhibits strongly nonlinear and hysteretic behavior,\nevidencing a granular regime dominated by nontrivial force-network dynamics."
    },
    {
        "anchor": "Terminal polydispersity in the crystallization of polydisperse\n  Lennard-Jones liquid: We find through computer simulations that the fractional volume change on\nfreezing of polydisperse Lennard-Jones liquid decreases with increasing\npolydispersity and approaches zero near a terminal polydispersity of 0.11,\nindependent of temperature. The transition however remains first order at\nterminal polydispersity. Average inherent structure (IS) energy of the\ncrystalline phase increases nearly quadratically with polydispersity indices\n({\\delta}) and marked by a crossover to nearly constant IS energy in the\namorphous phase.",
        "positive": "The equilibrium fluctuations of a semiflexible filament cross linked\n  into a network: We examine the equilibrium fluctuation spectrum of a constituent semiflexible\nfilament segment in a network. The effect of this cross linking is to modify\nthe mechanical boundary conditions at the end of the filament. We consider the\neffect of both tensile stress in the network, and its elastic compliance. Most\nsignificantly, the network's compliance introduces a nonlinear term into the\nfilament Hamiltonian even in the small-bending approximation. We analyze the\neffect of this nonlinearity upon the filament's fluctuation profile. We also\nfind that there are three principal fluctuation regimes dominated by one of the\nfollowing: (i) network tension, (ii) filament bending stiffness, or (iii)\nnetwork compliance. We propose that one can use observed filament fluctuations\nas a noninvasive probe of network tension, and we provide the necessary\nresponse function to quantitatively analyze this sort of \"tension\nmicrorheology\" in cross linked semiflexible filament networks."
    },
    {
        "anchor": "Packing-Limited Growth: We consider growing spheres seeded by random injection in time and space.\nGrowth stops when two spheres meet leading eventually to a jammed state. We\nstudy the statistics of growth limited by packing theoretically in d dimensions\nand via simulation in d=2, 3, and 4. We show how a broad class of such models\nexhibit distributions of sphere radii with a universal exponent. We construct a\nscaling theory that relates the fractal structure of these models to the decay\nof their pore space, a theory that we confirm via numerical simulations. The\nscaling theory also predicts an upper bound for the universal exponent and is\nin exact agreement with numerical results for d=4.",
        "positive": "Mermin-Ho vortex in ferromagnetic spinor Bose-Einstein condensates: The Mermin-Ho and Anderson-Toulouse coreless non-singular vortices are\ndemonstrated to be thermodynamically stable in ferromagnetic spinor\nBose-Einstein condensates with the hyperfine state F=1. The phase diagram is\nestablished in a plane of the rotation drive vs the total magnetization by\ncomparing the energies for other competing non-axis-symmetric or singular\nvortices. Their stability is also checked by evaluating collective modes."
    },
    {
        "anchor": "The connection between shear thinning and biaxial orientation for\n  quasi-ideal rods: The complete orientational ordering tensor of quasi-ideal colloidal rods is\nobtained as a function of shear rate by performing rheo-SANS (rheology with\nsmall angle neutron scattering) measurements on isotropic fd-virus suspensions\nin the two relevant scattering planes, the flow-gradient (1-2) and the\nflow-vorticity (1-3) plane. Microscopic ordering can be identified as the\norigin of the observed shear thinning. A qualitative description of the\nrheological response by Smoluchowski, as well as Doi--Edwards--Kuzuu theory is\npossible, as we obtain a master curve for different concentrations, scaling the\nshear rate with the apparent collective rotational diffusion coefficient.\nHowever, the observation suggests that the interdependence of ordering and\nshear thinning at small shear rates is stronger than predicted. The extracted\nzero-shear viscosity matches the concentration dependence of the self-diffusion\nof rods in semi-dilute solutions, while the director tilts close towards the\nflow direction already at very low shear rates. In contrast, we observe a\nsmaller dependence on the shear rate in the overall ordering at high shear\nrates, as well as an ever-increasing biaxiality.",
        "positive": "Using surface-wave spectroscopy to characterize tilt modes of a vortex\n  in a Bose-Einstein Condensate: A vortex in a condensate in a nonspherical trapping potential will in general\nexperience a torque. The torque will induce tilting of the direction of the\nvortex axis. We observe this behavior experimentally and show that by applying\nsmall distortions to the trapping potential, we can control the tilting\nbehaviour. By suppressing vortex tilt, we have been able to hold the vortex\naxis along the line of sight for up to 15 seconds. Alternatively, we can induce\na 180 degree tilt, effectively reversing the charge on the vortex as observed\nin the lab frame. We characterize the vortex non-destructively with a\nsurface-wave spectroscopic technique."
    },
    {
        "anchor": "On the network orientational affinity assumption in polymers and the\n  micro-macro connection through the chain stretch: We question the network affinity assumption in modeling chain orientations\nunder polymer deformations, and the use of the stretch measure projected from\nthe right Cauchy-Green deformation tensor (or non-affine micro-stretches\nderived from that measure) as a basic state variable for the micro-macro\ntransition. These ingredients are standard, taken from the statistical theory\nof polymers, and used in most micromechanical polymer network and soft tissue\nmodels.\n  The affinity assumption imposes a constraint in the network which results in\nan anisotropic distribution of the orientation of the chains and, hence, in an\nadditional configurational entropy that should be included. This additional\nentropy would result in an additional stress tensor. But an arguably more\nnatural alternative, in line with the typical assumption for the chain behavior\nitself and with the disregard of these forces, is to consider that the network\nmay fluctuate unconstrained to adapt to macroscopic deformations. This way, the\nisotropic statistical distribution of the orientation of the chains is\nmaintained unconstrained during deformation and no additional stress is\nimposed. Then, we show that this free-fluctuating network assumption is\nequivalent to consider the stretch projected from the stretch tensor (instead\nof the right Cauchy-Green deformation tensor) as the state variable for the\ndeformation of the network chains.\n  We show very important differences in predictions using both assumed\nbehaviors, and demonstrate that with the free-fluctuating network assumption,\nwe can obtain accurate predictions for all tests in polymers using just one\ntest curve to calibrate the model. With the same macro-micro-macro approach\nemploying the network affinity assumption, we are capable of capturing\naccurately only the test used for calibration of the model, but not the overall\npolymer behavior.",
        "positive": "Dynamic assembly of active colloids: theory and simulation: Because of consuming energy to drive their motion, systems of active colloids\nare intrinsically out of equilibrium. In the past decade, a variety of\nintriguing dynamic patterns have been observed in systems of active colloids,\nand they offer a new platform for studying non-equilibrium physics, in which\ncomputer simulation and analytical theory have played an important role. Here\nwe review the recent progress in understanding the dynamic assembly of active\ncolloids by using numerical and analytical tools. We review the progress in\nunderstanding the motility induced phase separation in the past decade,\nfollowed by the discussion on the effect of shape anisotropy and hydrodynamics\non the dynamic assembly of active colloids."
    },
    {
        "anchor": "A rheological signature of frictional interactions in shear thickening\n  suspensions: Colloidal shear thickening presents a significant challenge because the\nmacroscopic rheology becomes increasingly controlled by the microscopic details\nof short ranged particle interactions in the shear thickening regime. Our\nmeasurements here of the first normal stress difference over a wide range of\nparticle volume fraction elucidate the relative contributions from hydrodynamic\nlubrication and frictional contact forces, which have been debated. At moderate\nvolume fractions we find $N_1<0$, consistent with hydrodynamic models, however\nat higher volume fractions and shear stresses these models break down and we\ninstead observe dilation ($N_1>0$), indicating frictional contact networks.\nRemarkably, there is no signature of this transition in the viscosity, instead\nthis change in the sign of $N_1$ occurs while the shear thickening remains\ncontinuous. These results suggest a scenario where shear thickening is driven\nprimarily by the formation of frictional contacts, with hydrodynamic forces\nplaying a supporting role at lower concentrations. Motivated by this picture,\nwe introduce a simple model which combines these frictional and hydrodynamic\ncontributions and accurately fits the measured viscosity over a wide range of\nparticle volume fraction and shear stress.",
        "positive": "Surfing and crawling macroscopic active particles under strong\n  confinement -- inertial dynamics: We study two types of active (self-propelled) macroscopic particles under\nconfinement: camphor surfers and hexbug crawlers, using a combined\nexperimental, theoretical, and numerical approach. Unlike widely studied\nmicroscopic active particles and swimmers, where thermal forces are often\nimportant and inertia is negligible, our macroscopic particles exhibit complex\ndynamics due expressly to active non-thermal noise combined with inertial\neffects. Strong confinement induces accumulation at a finite distance within\nthe boundary and gives rise to three distinguishable dynamical states; both\ndepending on activity and inertia. These surprisingly complex dynamics arise\nalready at the single particle level -- highlighting the importance of inertia\nin macroscopic active matter."
    },
    {
        "anchor": "Phase heterogeneities of lipidic aggregates: We propose a model for explanation the \"domain-wall\" type configuration\nstates in binary lipid mixtures of cationic and neutral lipids, associated with\nobserved relaxation effects in their aggregates. We apply the analogy with\nformation of Kibble-\\.Zurek topological defects, which we suppose connected\nwith structural dynamics of the lipid phases. In frames of the proposed model,\nthe density of kink-type defects and the energy of the configurations are\ncalculated.",
        "positive": "Elastocapillary self-folding: buckling, wrinkling and collapse of\n  floating filaments: When a flexible filament is confined to a fluid interface, the balance\nbetween capillary attraction, bending resistance, and tension from an external\nsource can lead to a self-buckling instability. We perform an analysis of this\ninstability and provide analytical formulae that compare favorably with the\nresults of detailed numerical computations. The stability and long-time\ndynamics of the filament are governed by a single dimensionless elastocapillary\nnumber quantifying the ratio between capillary to bending stresses. Complex,\nfolded filament configurations such as loops, needles, and racquet shapes may\nbe reached at longer times, and long filaments can undergo a cascade of\nself-folding events."
    },
    {
        "anchor": "Micro-Macro Modeling of Polymeric Fluids and Shear-Induced Microscopic\n  Behaviors: This article delves into the micro-macro modeling of polymeric fluids,\nconsidering various microscopic potential energies, including the classical\nHookean potential, as well as newly proposed modified Morse and Elastic-plastic\npotentials. These proposed potentials encompass microscopic-scale bond-breaking\nprocesses. The development of a thermodynamically consistent micro-macro model\nis revisited, employing the energy variational method. To validate the model's\npredictions, we conduct numerical simulations utilizing a deterministic\nparticle-FEM method. Our numerical findings shed light on the distinct\nbehaviors exhibited by polymer chains at the micro-scale in comparison to the\nmacro-scale velocity and induced shear stresses of fluids under shear flow.\nNotably, we observe that polymer elongation, rotation, and bond breaking\ncontribute to the zero polymer-induced stress in the micro-macro model when\nemploying Morse and Elastic-plastic potentials. Furthermore, at high shear\nrates, polymer rotation is found to induce shear-thinning behavior in the model\nemploying the classical Hookean potential.",
        "positive": "Destruction of Bose-Einstein condensate by strong interactions: We study exactly soluble system of trapped bosonic particles interacting by a\nmodel harmonic forces. The model allows for detailed examination of the order\nparameter (condensate wave function) as well as concept of the off-diagonal and\ndiagonal order. We analyze the effect of interactions on the condensate and\nshow that sufficiently strong interactions, attractive or repulsive, lead to\ndestruction of the condensate. In the thermodynamic limit this destruction has\na critical character. It is shown that the existence of the coherent state of\nbosons is related to existence of two length scales determined by one- and\ntwo-particle reduced density matrices. The condensate can exist only if the two\nlength scales are of the same order. Interactions, both repulsive and\nattractive, change their relative size which may lead to destruction of\ncoherence in the system and depletion of the condensate. We suggest that this\nscenario is model independent."
    },
    {
        "anchor": "Intermittency and Velocity Fluctuations in Hopper Flows Prone to\n  Clogging: We experimentally study the dynamics of granular media in a discharging\nhopper. In such flows, there often appears to be a critical outlet size $D_c$\nsuch that the flow never clogs for $D > D_c$. We report on the time-averaged\nvelocity distributions, as well as temporal intermittency in the\nensemble-averaged velocity of grains in a viewing window, for both $D < D_c$\nand $D > D_c$, near and far from the outlet. We characterize the velocity\ndistributions by the standard deviation and the skewness of the distribution of\nvertical velocities. We propose a measure for intermittency based on the\ntwo-sample Kolmogorov-Smirnov $D_{KS}$-statistic for the velocity distributions\nas a function of time. We find that there is no discontinuity or kink in these\nvarious measures as a function of hole size. This result supports the\nproposition that there is no well-defined $D_c$ and that clogging is always\npossible. Furthermore, the intermittency time scale of the flow is set by the\nspeed of the grains at the hopper exit. This latter finding is consistent with\na model of clogging as the independent sampling for stable configurations at\nthe exit with a rate set by the exiting grain speed [Thomas and Durian, Phys.\nRev. Lett. (2015)].",
        "positive": "Droplet microfluidics to prepare magnetic polymer vesicles and to\n  confine the heat in magnetic hyperthermia: In this work, we present two types of microfluidic chips involving magnetic\nnanoparticles dispersed in cyclohexane with oleic acid. In the first case, the\nhydrophobically coated nanoparticles are self-assembled with an amphiphilic\ndiblock copolymer by a double-emulsion process in order to prepare giant\nmagnetic vesicles (polymersomes) in one step and at a high throughput. It was\nshown in literature that such diblock copolymer W/O/W emulsion droplets can\nevolve into polymersomes made of a thin (nanometric) magnetic membrane through\na dewetting transition of the oil phase from the aqueous internal cores usually\nleading to \"acorn-like\" structures (polymer excess) sticking to the membranes.\nTo address this issue and greatly speed up the process, the solvent removal by\nevaporation was replaced by a \"shearing-off\" of the vesicles in a simple PDMS\nchip designed to exert a balance between a magnetic gradient and viscous shear.\nIn the second example, a simple oil-in-oil emulsion chip is used to obtain\nregular trains of magnetic droplets that circulate inside an inductor coil\nproducing a radio-frequency magnetic field. We evidence that the heat produced\nby magnetic hyperthermia can be converted into a temperature rise even at the\nscale of nL droplets. The results are compared to heat transfer models in two\nlimiting cases: adiabatic vs. dissipative. The aim is to decipher the delicate\npuzzle about the minimum size required for a tumor \"phantom\" to be heated by\nradio-frequency hyperthermia in a general scope of anticancer therapy."
    },
    {
        "anchor": "Scale-free center-of-mass displacement correlations in dense polymer\n  solutions and melts without topological constraints and momentum\n  conservation: A bond-fluctuation model study: By Monte Carlo simulations of a variant of the bond-fluctuation model without\ntopological constraints we examine the center-of-mass (COM) dynamics of polymer\nmelts in $d=3$ dimensions. Our analysis focuses on the COM displacement\ncorrelation function $\\CN(t) \\approx \\partial_t^2 \\MSDcmN(t)/2$, measuring the\ncurvature of the COM mean-square displacement $\\MSDcmN(t)$. We demonstrate that\n$\\CN(t) \\approx -(\\RN/\\TN)^2 (\\rhostar/\\rho) \\ f(x=t/\\TN)$ with $N$ being the\nchain length ($16 \\le N \\le 8192$), $\\RN\\sim N^{1/2}$ the typical chain size,\n$\\TN\\sim N^2$ the longest chain relaxation time, $\\rho$ the monomer density,\n$\\rhostar \\approx N/\\RN^d$ the self-density and $f(x)$ a universal function\ndecaying asymptotically as $f(x) \\sim x^{-\\omega}$ with $\\omega = (d+2) \\times\n\\alpha$ where $\\alpha = 1/4$ for $x \\ll 1$ and $\\alpha = 1/2$ for $x \\gg 1$. We\nargue that the algebraic decay $N \\CN(t) \\sim - t^{-5/4}$ for $t \\ll \\TN$\nresults from an interplay of chain connectivity and melt incompressibility\ngiving rise to the correlated motion of chains and subchains.",
        "positive": "Ground state of two unlike charged colloids: An analogy with ionic\n  bonding: In this letter, we study the ground state of two spherical macroions of\nidentical radius, but asymmetric bare charge ((Q_{A}>Q_{B})). Electroneutrality\nof the system is insured by the presence of the surrounding divalent\ncounterions. Using Molecular Dynamics simulations within the framework of the\nprimitive model, we show that the ground state of such a system consists of an\novercharged and an undercharged colloid. For a given macroion separation the\nstability of these ionized-like states is a function of the difference\n((\\sqrt{N_{A}}-\\sqrt{N_{B}})) of neutralizing counterions (N_{A}) and (N_{B}).\nFurthermore the degree of ionization, or equivalently, the degree of\novercharging, is also governed by the distance separation of the macroions. The\nnatural analogy with ionic bonding is briefly discussed."
    },
    {
        "anchor": "Nonequilibrium adsorption of 2AnB patchy colloids on substrates: We study the irreversible adsorption of spherical $2AnB$ patchy colloids\n(with two $A$-patches on the poles and $n$ $B$-patches along the equator) on a\nsubstrate. In particular, we consider dissimilar $AA$, $AB$, and $BB$ binding\nprobabilities. We characterize the patch-colloid network and its dependence on\n$n$ and on the binding probabilities. Two growth regimes are identified with\ndifferent density profiles and we calculate a growth mode diagram as a function\nof the colloid parameters. We also find that, close to the substrate, the\ndensity of the network, which depends on the colloid parameters, is\ncharacterized by a depletion zone.",
        "positive": "Elastic Models for the Non-Arrhenius Relaxation Time of Glass-Forming\n  Liquids: We first review the phenomenology of viscous liquids and the standard models\nused for explaining the non-Arrhenius average relaxation time. Then the focus\nis turned to the so-called elastic models, arguing that these models are all\nequivalent in the Einstein approximation (where the short-time elastic\nproperties are all determined by just one effective, temperature-dependent\nforce constant). We finally discuss the connection between the elastic models\nand two well-established research fields of condensed-matter physics: point\ndefects in crystals and solid-state diffusion."
    },
    {
        "anchor": "Crackling to periodic dynamics in sheared granular media: The local and global dynamics of a sheared granular medium are studied in a\nmodel experiment as a function of several macroscopic parameters. We observe\nthat by changing the shear rate or the loading stiffness, the system crackles,\nwith intermittent slip avalanches, or exhibits periodic motion. By analyzing\nthe global force, induced while shearing, we capture the transition from the\ncrackling to the periodic regime and associated scaling laws. We deduce a novel\ndynamic phase diagram as a function of the shear rate and the system's\nstiffness. Using photo-elasticimetry, we also capture the grain-scale stress\nevolution, and investigate the microscopic behavior in the different regimes.",
        "positive": "'Fuelled' motion: phoretic motility and collective behaviour of active\n  colloids: Designing microscopic and nanoscopic self-propelled particles and\ncharacterising their motion has become a major scientific challenge over the\npast decades. To this purpose, phoretic effects, namely propulsion mechanisms\nrelying on local field gradients, have been the focus of many theoretical and\nexperimental studies. In this review, we adopt a tutorial approach to present\nthe basic physical mechanisms at stake in phoretic motion, and describe the\ndifferent experimental works that lead to the fabrication of active particles\nbased on this principle. We also present the collective effects observed in\nassemblies of interacting active colloids, and the theoretical tools that have\nbeen used to describe phoretic and hydrodynamic interactions."
    },
    {
        "anchor": "First-principles molecular dynamics study of deuterium diffusion in\n  liquid tin: Understanding the retention of hydrogen isotopes in liquid metals, such as\nlithium and tin, is of great importance in designing a liquid plasma-facing\ncomponent in fusion reactors. However, experimental diffusivity data of\nhydrogen isotopes in liquid metals are still limited or controversial. We\nemploy first-principles molecular dynamics simulations to predict diffusion\ncoefficients of deuterium in liquid tin at temperatures ranging from 573 to\n1673 K. Our simulations indicate faster diffusion of deuterium in liquid tin\nthan the self-diffusivity of tin. In addition, we find that the structural and\ndynamic properties of tin are insensitive to the inserted deuterium at\ntemperatures and concentrations considered. We also observe that tin and\ndeuterium do not form stable solid compounds. These predicted results from\nsimulations enable us to have a better understanding of the retention of\nhydrogen isotopes in liquid tin.",
        "positive": "Paradoxes for Chromonic Liquid Crystal Droplets: Chromonic liquid crystals constitute a novel lyotropic phase, whose elastic\nproperties have so far been modeled within the classical Oseen-Frank theory,\nprovided that the twist constant is assumed to be considerably smaller than the\nsaddle-splay constant, in violation of one Ericksen inequality. This paper\nshows that paradoxical consequences follow from such a violation for droplets\nof these materials surrounded by an isotropic fluid. For example, tactoids with\na degenerate planar anchoring simply disintegrate indefinitely in myriads of\nsmaller ones."
    },
    {
        "anchor": "Crosslinked biopolymer bundles: crosslink reversibility leads to\n  cooperative binding/unbinding phenomena: We consider a biopolymer bundle consisting of filaments that are crosslinked\ntogether. The crosslinks are reversible: they can dynamically bind and unbind\nadjacent filament pairs as controlled by a binding enthalpy. The bundle is\nsubjected to a bending deformation and the corresponding distribution of\ncrosslinks is measured. For a bundle consisting of two filaments, upon\nincreasing the bending amplitude, a first-order transition is observed. The\ntransition is from a state where the filaments are tightly coupled by many\nbound crosslinks, to a state of nearly independent filaments with only a few\nbound crosslinks. For a bundle consisting of more than two filaments, a series\nof first-order transitions is observed. The transitions are connected with the\nformation of an interface between regions of low and high crosslink densities.\nCombining umbrella sampling Monte Carlo simulations with analytical\ncalculations, we present a detailed picture of how the competition between\ncrosslink shearing and filament stretching drives the transitions. We also find\nthat, when the crosslinks become soft, collective behavior is not observed: the\ncrosslinks then unbind one after the other leading to a smooth decrease of the\naverage crosslink density.",
        "positive": "Buckling patterns of complete spherical shells filled with an elastic\n  medium under external pressure: The critical buckling characteristics of hydrostatically pressurized complete\nspherical shells filled with an elastic medium are demonstrated. A model based\non small deflection thin shell theory, the equations of which are solved in\nconjunction with variational principles, is presented. In the exact\nformulation, axisymmetric and inextensional assumptions are not used initially\nand the elastic medium is modelled as a Winkler foundation, i.e., using\nuncoupled radial springs with a constant foundation modulus that is independent\nof wave numbers of shell buckling modes. Simplified approximations based on a\nRayleigh-Ritz approach are also introduced for critical buckling pressure and\nmode number with a considerable degree of accuracy. Characteristic modal shapes\nare demonstrated for a wide range of material and geometric parameters. A phase\ndiagram is established to obtain the requisite thickness to radius, and\nstiffness ratios for a desired mode profile. The present exact formulation can\nbe readily extended to apply to more general cases of non-axisymmetric buckling\nproblems."
    },
    {
        "anchor": "Configurational stability of a crack propagating in a material with\n  mode-dependent fracture energy - Part I: Mixed-mode I+III: In a previous paper (Leblond et al., 2011), we proposed a theoretical\ninterpretation of the experimentally well known instability of coplanar crack\npropagation in mode I+III. The interpretation relied on a stability analysis\nbased on analytical expressions of the stress intensity factors for a crack\nslightly perturbed both within and out of its original plane, due to Gao and\nRice (1986) and Movchan et al. (1998), coupled with a double propagation\ncriterion combining Griffith's energetic condition and principle of local\nsymmetry. Under such assumptions instability modes were indeed evidenced for\nvalues of the mode mixity ratio of the mode III to mode I stress intensity\nfactors applied remotely larger than some threshold depending only on Poisson's\nratio. Unfortunately, the predicted thresholds were much larger than those\ngenerally observed for typical values of this material parameter. While the\nsubcritical character of the nonlinear bifurcation from coplanar to fragmented\nfronts has been proposed as a possible explanation for this discrepancy (Chen\net al., 2015), we propose here an alternative explanation based on the\nintroduction of a constitutive relationship between the fracture energy and the\nmode mixity ratio, which is motivated by experimental observations. By\nreexamining the linear stability analysis of a planar propagating front, we\nshow that such a relationship suffices, provided that it is strong enough, to\nlower significantly the threshold value of the mode mixity ratio for\ninstability so as to bring it in a range more consistent with experiments.\nInteresting formulae are also derived for the distributions of the perturbed\nstress intensity factors and energy release rate, in the special case of\nperturbations of the crack surface and front obeying the principle of local\nsymmetry and having reached a stationary state.",
        "positive": "Piercing an interface with a brush: collaborative stiffening: The hairs of a painting brush withdrawn from a wetting liquid self-assemble\ninto clumps whose sizes rely on a balance between liquid surface tension and\nhairs bending rigidity. Here we study the situation of an immersed carpet in an\nevaporating liquid bath : the free extremities of the hairs are forced to\npierce the liquid interface. The compressive capillary force on the tip of\nflexible hairs leads to buckling and collapse. However we find that the\nspontaneous association of hairs into stronger bundles may allow them to resist\ncapillary buckling. We explore in detail the different structures obtained and\ncompare them with similar patterns observed in micro-structured surfaces such\nas carbon nanotubes \"forests\"."
    },
    {
        "anchor": "Particle Size Effects in Flow-Stabilized Solids: Flow-stabilized solids are a class of fragile matter that forms when a dense\nsuspension of colloids accumulates against a semi-permeable barrier, for flow\nrates above a critical value. In order to probe the effect of particle size on\nthe formation of these solids, we perform experiments on micron-sized\nmonodisperse spherical polystyrene spheres in a Hele-Shaw geometry. We examine\nthe spatial extent, internal fluctuations, and fluid permeability of the solids\ndeposited against the barrier, and find that these do not scale with the\nP\\'eclet number. Instead, we find distinct behaviors at higher Peclet numbers,\nsuggesting a transition from thermal- to athermal-solids which we connect to\nparticle-scale fluctuations in the liquid-like layer at the upstream surface of\nthe solid. We further observe that while the Carman-Kozeny model does not\naccurately predict the permeability of flow-stabilized solids, we do find a new\nscaling which predicts the permeability.",
        "positive": "Exact transport coefficients from the inelastic rough Maxwell model of a\n  granular gas: Granular gases demand models capable of capturing their distinct\ncharacteristics. The widely employed inelastic hard-sphere model (IHSM)\nintroduces complexities that are compounded when incorporating realistic\nfeatures like surface roughness and rotational degrees of freedom, resulting in\nthe more intricate inelastic rough hard-sphere model (IRHSM). This paper\nfocuses on the inelastic rough Maxwell model (IRMM), presenting a more\ntractable alternative to the IRHSM and enabling exact solutions. Building on\nthe foundation of the inelastic Maxwell model (IMM) applied to granular gases,\nthe IRMM extends the mathematical representation to encompass surface roughness\nand rotational degrees of freedom. The primary objective is to provide exact\nexpressions for the Navier--Stokes--Fourier transport coefficients within the\nIRMM, including shear viscosity, bulk viscosity, cooling-rate transport\ncoefficient, thermal conductivity, and Dufour-like coefficient. In contrast to\nearlier approximations in the IRHSM, our study unveils inherent couplings, such\nas shear viscosity to spin viscosity and thermal conductivity to counterparts\nassociated with a cross flux vector. These exact findings provide valuable\ninsights into refining the Sonine approximation applied to the IRHSM,\ncontributing to a deeper understanding of the transport properties in granular\ngases with realistic features."
    },
    {
        "anchor": "Fourth virial coefficients of asymmetric nonadditive hard-disc mixtures: The fourth virial coefficient of asymmetric nonadditive binary mixtures of\nhard disks is computed with a standard Monte Carlo method. Wide ranges of size\nratio ($0.05\\leq q\\leq 0.95$) and nonadditivity ($-0.5\\leq \\Delta\\leq 0.5$) are\ncovered. A comparison is made between the numerical results and those that\nfollow from some theoretical developments. The possible use of these data in\nthe derivation of new equations of state for these mixtures is illustrated by\nconsidering a rescaled virial expansion truncated to fourth order. The\nnumerical results obtained using this equation of state are compared with Monte\nCarlo simulation data in the case of a size ratio $q=0.7$ and two\nnonadditivities $\\Delta=\\pm 0.2$.",
        "positive": "Shape-dynamic growth, structure, and elasticity of homogeneously\n  oriented spherulites in an isotropic/smectic-A mesophase transition: A Landau-de Gennes model that integrates the nematic quadrupolar tensor order\nparameter and complex smectic-A order parameters is used to simulate the\ntwo-dimensional growth of an initially homogeneous smectic-A spherulite in an\nisotropic matrix. These simulations are performed in the shape-dynamic\n(nano-scale) regime of growth under two material conditions: isotropic nematic\nelasticity and equal splay-bend nematic elasticity. A comparison of the growth\nkinetics, spherulite morphology, interfacial/bulk energy landscapes between\nboth cases is made showing that equal nematic splay-bend elasticity is required\nto reproduce past experimental and theoretical observations. Additionally, a\npreviously unknown undulation instability during spherulite growth is found\nwhich, in conjunction with preferred planar anchoring and defect shedding\nmechanisms at micron length scales, could explain the formation mechanism of\nfocal conic curvature defects and ultimately smectic-A \"batonnet\" structures\nobserved experimentally."
    },
    {
        "anchor": "Apparatus for simultaneous DLS-SANS investigations of dynamics and\n  structure in soft matter: Dynamic Light Scattering (DLS) and Small-Angle Neutron Scattering (SANS) are\ntwo key tools with which to probe the dynamic and static structure factor,\nrespectively, in soft matter. Usually DLS and SANS measurements are performed\nseparately, in different laboratories, on different samples and at different\ntimes. However, this methodology has particular disadvantages for a large\nvariety of soft materials which exhibit high sensitivity to small changes in\nfundamental parameters such as waiting times, concentration, pH, ionic\nstrength, etc. Here we report on a new portable DLS-SANS apparatus that allows\none to simultaneously measure both the microscopic dynamics (through DLS) and\nthe static structure (through SANS) on the same sample. The apparatus has been\nconstructed as a collaboration between two laboratories, each an expert in one\nof the scattering methods, and was commissioned on the \\textit{LOQ} and\n\\textit{ZOOM} SANS instruments at the ISIS Pulsed Neutron \\& Muon Source, U.K.",
        "positive": "A dynamical theory of homogeneous nucleation for colloids and\n  macromolecules: Homogeneous nucleation is formulated within the context of fluctuating\nhydrodynamics. It is shown that for a colloidal or macromolecular system in the\nstrong damping limit the most likely path for nucleation can be determined by\ngradient descent in density space governed by a nontrivial metric fixed by the\ndynamics. The theory provides a justification and extension of more heuristic\nequilibrium approaches based solely on the free energy. It is illustrated by\napplication to liquid-vapor nucleation where it is shown that, in contrast to\nmost free energy-based studies, the smallest clusters correspond to long\nwavelength, small amplitude perturbations."
    },
    {
        "anchor": "Using Active Matter to Introduce Spatial Heterogeneity to the\n  Susceptible-Infected-Recovered Model of Epidemic Spreading: The widely used susceptible-infected-recovered (S-I-R) epidemic model assumes\na uniform, well-mixed population, and incorporation of spatial heterogeneities\nremains a major challenge. Understanding failures of the mixing assumption is\nimportant for designing effective disease mitigation approaches. We combine a\nrun-and-tumble self-propelled active matter system with an S-I-R model to\ncapture the effects of spatial disorder. Working in the motility-induced phase\nseparation regime both with and without quenched disorder, we find two epidemic\nregimes. For low transmissibility, quenched disorder lowers the frequency of\nepidemics and increases their average duration. For high transmissibility, the\nepidemic spreads as a front and the epidemic curves are less sensitive to\nquenched disorder; however, within this regime it is possible for quenched\ndisorder to enhance the contagion by creating regions of higher particle\ndensities. We discuss how this system could be realized using artificial\nswimmers with mobile optical traps operated on a feedback loop.",
        "positive": "Hierarchical excluded volume screening in solutions of bottlebrush\n  polymers: Polymer bottlebrushes provide intriguing features being relevant both in\nnature and in synthetic systems. While their presence in the articular\ncartilage optimizes synovial joint lubrication, bottlebrushes offer pathways\nfor fascinating applications, such as within super- soft elastomers or for drug\ndelivery. However, the current theoretical understanding lacks completeness,\nprimarily due to the complicated interplay of many length scales. Herein, we\ndevelop an analytical model that demonstrates how structural properties of\nbottlebrushes depend on the concentration, ranging from dilute solutions to\nhighly concentrated melts. The validity of our model is supported by data from\nextensive molecular dynamics simulation. We demonstrate that the hierarchical\nstructure of bottlebrushes dictates a sequence of conformational changes as the\nsolution concentration increases. The effect is mediated by screening\nofexcluded volume interactions atsubsequent structural parts ofthe\nbottlebrushes. Our findings provide important insights that should enable\nimproved customization of novel materials based on the architectural design of\npolymer bottlebrushes."
    },
    {
        "anchor": "Crystallization of a polymer on a surface: We have studied the structure and free energy landscape of a semi-flexible\nlattice-polymer in the presence of a surface. At low temperatures coexistence\nof two-dimensional integer-folded crystals is observed. As the temperature is\nincreased there is a transition from these crystalline configurations to a\ndisordered coil adsorbed onto the surface. The polymer then gradually develops\nthree-dimensional character at higher temperatures. We compute the free energy\nas a function of increasing crystallinity and compare with the free energy\nprofiles assumed by the Lauritizen-Hoffman surface nucleation theory of polymer\ncrystallization. Our free energy profiles exhibit a `sawtooth' structure\nassociated with the successive formation of chain folds. However, in the early\nstages of crystallization our profiles significantly deviate from those assumed\nby surface nucleation theory because the initial nucleus is not a single stem\nbut two incomplete stems connected by a fold. This finding has significant\nimplications for the theoretical description of polymer crystallization.",
        "positive": "Diffusive regimes in a two-dimensional chiral fluid: Diffusion is a fundamental aspect of transport processes in biological\nsystems, and thus, in the development of life itself. And yet, the diffusive\ndynamics of active fluids with directed rotation, known as chiral fluids, has\nnot been analyzed in detail so far. Here, we describe the diffusive regimes of\na two-dimensional chiral fluid, composed in this case of a set of identical\ndisk-shaped rotors. We found strong experimental evidence of odd diffusion.\nThis odd diffusion emerges in the form of a two-dimensional tensor with an\nantisymmetric part. In particular, we show that chiral diffusion is complex,\nfeaturing transitions between super, quasi-normal, and sub diffusion, and very\nslowly aging. Moreover, we show that the diffusion tensor elements, including\noff-diagonal elements; i.e., odd diffusion coefficient, change sign according\nto flow vorticity. Therefore, the chiral fluid has a self regulated diffusion,\ncontrolled by its vorticity."
    },
    {
        "anchor": "Hydrodynamic fluctuations of liquids with internal rotation inside a\n  pore: The correlation theory of the thermal hydrodynamic fluctuations of liquids\nwith internal spin within a spherical cavity is developed. For the hydrodynamic\nfields of such a liquid, linearized equations with random thermal sources are\nused. For the time dependent amplitudes of the expansion of the fields in the\nbasis functions of the vector Helmholtz equations a set of Langevin equations\nis obtained that allowed us, with the help of the fluctuation-dissipation\ntheorem, to find the spectral densities of the correlation functions of the\namplitudes. The spectra of the fluctuations of hydrodynamic fields are found in\nthe form of a superposition of spectral amplitudes of the expansion with\nweights expressed as bilinear combinations of the proper coordinate functions\nand their derivatives. The correlation functions of the field of the\ntranslational velocity and internal spin of the liquid in one spatial point are\nanalyzed. They have a sense of local coefficients of the translational and\nrotational diffusion coefficients of the Lagrange particle. We represent them\nas a series in spherical Bessel functions and roots of transcendental equations\nfollowing from the boundary conditions on the sphere. The results demonstrate\nthat the size of the pore essentially affects the character of the hydrodynamic\nfluctuations of the liquid.",
        "positive": "A self-propelled particle in an external potential: is there an\n  effective temperature?: We study a stationary state of a single self-propelled, athermal particle in\nlinear and quadratic external potentials. The self-propulsion is modeled as a\nfluctuating force evolving according to the Ornstein-Uhlenbeck process,\nindependently of the state of the particle. Without an external potential, in\nthe long time limit, the self-propelled particle moving in a viscous medium\nperforms diffusive motion, which allows one to identify an effective\ntemperature. We show that in the presence of a linear external potential the\nstationary state distribution has an exponential form with the sedimentation\nlength determined by the effective temperature of the free self-propelled\nparticle. In the presence of a quadratic external potential the stationary\nstate distribution has a Gaussian form. However, in general, this distribution\nis not determined by the effective temperature of the free self-propelled\nparticle."
    },
    {
        "anchor": "Phase Separation of Charge-Stabilized Colloids: A Gibbs Ensemble Monte\n  Carlo Simulation Study: Fluid phase behavior of charge-stabilized colloidal suspensions is explored\nby applying a new variant of the Gibbs ensemble Monte Carlo simulation method\nto a coarse-grained one-component model with implicit microions and solvent.\nThe simulations take as input linear-response approximations for effective\nelectrostatic interactions -- hard-sphere-Yukawa pair potential and one-body\nvolume energy. The conventional Gibbs ensemble trial moves are supplemented by\nexchange of (implicit) salt between coexisting phases, with acceptance\nprobabilities influenced by the state dependence of the effective interactions.\nCompared with large-scale simulations of the primitive model, with explicit\nmicroions, our computationally practical simulations of the one-component model\nclosely match the pressures and pair distribution functions at moderate\nelectrostatic couplings. For macroion valences and couplings within the\nlinear-response regime, deionized aqueous suspensions with monovalent microions\nexhibit separation into macroion-rich and macroion-poor fluid phases below a\ncritical salt concentration. The resulting pressures and phase diagrams are in\nexcellent agreement with predictions of a variational free energy theory based\non the same model.",
        "positive": "Explicit secular equation for Scholte waves over a monoclinic crystal: The aim of this Letter is to derive explicitly the secular equation for\nScholte waves at the interface between a fluid and an anisotropic crystal cut\nalong a plane containing the normal to a single symmetry plane, that is\ncontaining only one crystallographic axis."
    },
    {
        "anchor": "Reentrant Transitions in a Mixture of Small and Big Particles\n  Interacting via Soft Repulsive Potential: We report the first observation of temperature-controlled reentrant\ntransition in simulations of mixtures of small and big particles interacting\nvia soft repulsive potential in 2D. As temperature increases, the system passes\nfrom a fluid mixture, to a crystal of big particles in a fluid of small\nparticles and back to a fluid mixture. Solidification is driven by entropy gain\nof small particles which overcomes the free energy cost of confining big ones.\nMelting results from enhanced interpenetration of particles at high temperature\nwhich reduces the entropic forces that stabilize the crystal.",
        "positive": "Enriched Computational Homogenization Schemes Applied to\n  Pattern-Transforming Elastomeric Mechanical Metamaterials: Elastomeric mechanical metamaterials exhibit unconventional mechanical\nbehaviour owing to their complex microstructures. A clear transition in the\neffective properties emerges under compressive loading, which is triggered by\nlocal instabilities and pattern transformations of the underlying cellular\nmicrostructure. Such transformations trigger a non-local mechanical response\nresulting in strong size effects. For predictive modelling of engineering\napplications, the effective homogenized material properties are generally of\ninterest. For mechanical metamaterials, these can be obtained in an expensive\nmanner by ensemble averaging of the direct numerical simulations for a series\nof translated microstructures, applicable especially in the regime of small\nseparation of scales. To circumvent this expensive step, computational\nhomogenization methods are of benefit, employing volume averaging instead.\nClassical first-order computational homogenization, which relies on the\nstandard separation of scales principle, is unable to capture any size and\nboundary effects. Second-order computational homogenization has the ability to\ncapture strain gradient effects at the macro-scale, thus accounting for the\npresence of non-localities. Another alternative is micromorphic computational\nhomogenization scheme, which is tailored to pattern-transforming metamaterials\nby incorporating prior kinematic knowledge. In this contribution, a systematic\nstudy is performed, assessing the predictive ability of computational\nhomogenization schemes in the realm of elastomeric metamaterials. Three\nrepresentative examples with distinct mechanical loading are employed for this\npurpose: uniform compression and bending of an infinite specimen, and\ncompression of a finite specimen. Qualitative and quantitative analyses are\nperformed for each of the load cases where the ensemble average solution is set\nas a reference."
    },
    {
        "anchor": "Critical fluctuations and anomalous transport in soft Yukawa-Langevin\n  systems: Simulation of a Langevin-dynamics model demonstrates emergence of critical\nfluctuations and anomalous grain transport which have been observed in\nexperiments on \"soft\" quasi-two-dimensional dusty plasma clusters. It has been\nsuggested that these anomalies derive from particular non-equilibrium physics,\nbut our model does not contain such physics: the grains are confined by an\nexternal potential, interact via static Yukawa forces, and are subject to\nstochastic heating and dissipation from neutrals. One remarkable feature is\nemergence of leptokurtic probability distributions of grain displacements\n$\\xi(\\tau)$ on time-scales $\\tau<\\tau_{\\Delta}$, where $\\tau_{\\Delta}$ is the\ntime at which the standard deviation $\\sigma(\\tau)\\equiv < \\xi^2(\\tau) >^{1/2}$\napproaches the mean inter-grain distance $\\Delta$. Others are development of\nhumps in the distributions on multiples of $\\Delta$, anomalous Hurst exponents,\nand transitions from leptokurtic towards Gaussian displacement distributions on\ntime scales $\\tau>\\tau_{\\Delta}$. The latter is a signature of intermittency,\nhere interpreted as a transition from bursty transport associated with hopping\non intermediate time scales to vortical flows on longer time scales.",
        "positive": "Fundamentals and advances in magnetic hyperthermia: Nowadays, magnetic hyperthermia constitutes a complementary approach to\ncancer treatment. The use of magnetic particles as heating mediators, proposed\nin the 1950s, provides a novel strategy for improving tumor treatment and,\nconsequently, patient quality of life. This review reports a broad overview\nabout several aspects of magnetic hyperthermia addressing new perspectives and\nthe progress on relevant features such as the ad hoc preparation of magnetic\nnanoparticles, physical modeling of magnetic heating, methods to determine the\nheat dissipation power of magnetic colloids including the development of\nexperimental apparatus and the influence of biological matrices on the heating\nefficiency."
    },
    {
        "anchor": "Encapsulated bacteria deform lipid vesicles into flagellated swimmers: We study a synthetic system of motile Escherichia coli bacteria encapsulated\ninside giant lipid vesicles. Forces exerted by the bacteria on the inner side\nof the membrane are sufficient to extrude membrane tubes filled with one or\nseveral bacteria. We show that a physical coupling between the membrane tube\nand the flagella of the enclosed cells transforms the tube into an effective\nhelical flagellum propelling the vesicle. We develop a simple theoretical model\nto estimate the propulsive force from the speed of the vesicles, and\ndemonstrate the good efficiency of this coupling mechanism. Together, these\nresults point to design principles for conferring motility to synthetic cells.",
        "positive": "Hydrodynamic radius approximation for spherical particles suspended in a\n  viscous fluid: influence of particle internal structure and boundary: Systems of spherical particles moving in Stokes flow are studied for a\ndifferent particle internal structure and boundaries, including the Navier-slip\nmodel. It is shown that their hydrodynamic interactions are well described by\ntreating them as solid spheres of smaller hydrodynamic radii, which can be\ndetermined from measured single-particle diffusion or intrinsic viscosity\ncoefficients. Effective dynamics of suspensions made of such particles is quite\naccurately described by mobility coefficients of the solid particles with the\nhydrodynamic radii, averaged with the unchanged direct interactions between the\nparticles."
    },
    {
        "anchor": "Light-responsive nematic colloids and colloidal crystals: Rational control over the periodic arrangement of particles by means of\nexternal stimuli is a technologically important aspect of colloidal science\nwith important physical underpinnings. Here, a robust structural control of\nparticle assemblies in a nematic liquid crystal (NLC) is demonstrated by\ndissolving trace amounts of light-responsive azo-dendrimer molecules which\nspontaneously get adsorbed on the particle surface. The azo-dendrimer molecules\nin the presence of external UV irradiation undergo conformational change\n(trans-cis); as a result, they transmit the mechanical torque to surrounding LC\nmolecules and alter the near-field director orientation. The director\nre-orientation at the surface of the particles causes topological defect\ntransformation which involves elastic dipoles, quadrupoles and hexadecapoles.\nThe defect transformation can be emulated in colloidal assemblies towards\ndifferent purposes such as rotation of chains and restructuring of 2D colloidal\ncrystals. In this study, various topological aspects of light-activated defect\ntransformation and its application in the collective manipulation of colloidal\nassemblies are presented.",
        "positive": "Configurational Forces in Penetration Processes: With a loose reference to problems of penetration in biomechanics (for\ninstance, a nanoparticle penetrating through a cell's membrane or a cell sucked\nwith a pipette), the role of configurational forces is investigated during the\nprocess in which a compliant intruder is inserted into an elastic structure.\nFor insertion into a rigid constraint, a configurational force proportional to\nthe square of the strain needed to deform the body, which is penetrating, is\nfound. This force has a more complex structure when the compliance of the\nconstraint is kept into account, but in all cases, it tends to expel the\npenetrating body."
    },
    {
        "anchor": "Meso-scale computer modeling of lipid-DNA complexes for gene therapy: We report on a molecular simulation method which captures the self-assembly\nof cationic lipid-DNA (CL-DNA) gene delivery complexes. Computational\nefficiency required for large length- and time-scale simulations is achieved\nthrough a coarse-grained representation of the intra-molecular details, and via\ninter-molecular potentials, which effectively mimic the hydrophobic effect {\\em\nwithout} explicit solvent. In addition to showing spontaneous self-assembly of\ncomplexes, the broad utility of the model is illustrated by demonstrating\nexcellent agreement with X-ray diffraction experimental data for the dependence\nof the spacing between DNA chains on the concentration of CLs. At high\nconcentrations, the large electrostatic pressure induce the formation of pores\nin the membranes through which the DNA molecules may escape the complex. We\nrelate this observation to the origin of recently observed enhanced\ntransfection efficiency of lamellar CL-DNA complexes at high charge densities.",
        "positive": "Local vortex nucleation and the surface mode spectrum of large\n  condensates: A combination of analytical and numerical approaches obtains the complete\ndispersion curve for surface excitations in a condensate held in a plane linear\npotential. This improvement on previous approximate results yields an accurate\nformula for the local Landau critical velocity for vortex nucleation at the\nsurface of a sufficiently large condensate, which agrees very well with recent\nexperiments. The dispersion curve for surface modes at a hard wall potential is\nalso presented, for contrast."
    },
    {
        "anchor": "Dynamics and Scaling of 2D Polymers in a Dilute Solution: The breakdown of dynamical scaling for a dilute polymer solution in 2D has\nbeen suggested by Shannon and Choy [Phys. Rev. Lett. {\\bf 79}, 1455 (1997)].\nHowever, we show here both numerically and analytically that dynamical scaling\nholds when the finite-size dependence of the relevant dynamical quantities is\nproperly taken into account. We carry out large-scale simulations in 2D for a\npolymer chain in a good solvent with full hydrodynamic interactions to verify\ndynamical scaling. This is achieved by novel mesoscopic simulation techniques.",
        "positive": "Active nematic gels as active relaxing solids: I put forward a continuum theory for active nematic gels, defined as fluids\nor suspensions of orientable rodlike objects endowed with active dynamics, that\nis based on symmetry arguments and compatibility with thermodynamics. The\nstarting point is our recent theory that models (passive) nematic liquid\ncrystals as relaxing nematic elastomers. The interplay between viscoelastic\nresponse and active dynamics of the microscopic constituents is naturally taken\ninto account. By contrast with standard theories, activity is not introduced as\nan additional term of the stress tensor, but it is added as an external\nremodeling force that competes with the passive relaxation dynamics and drags\nthe system out of equilibrium. In a simple one-dimensional channel geometry, we\nshow that the interaction between non-uniform nematic order and activity\nresults in either a spontaneous flow of particles or a self-organization into\nsub-channels flowing in opposite directions."
    },
    {
        "anchor": "Beyond Pairwise: Higher-order physical interactions affect phase\n  separation in multi-component liquids: Phase separation, crucial for spatially segregating biomolecules in cells, is\nwell-understood in the simple case of a few components with pairwise\ninteractions. Yet, biological cells challenge the simple picture in at least\ntwo ways: First, biomolecules, like proteins and nucleic acids, exhibit\ncomplex, higher-order interactions, where a single molecule may interact with\nmultiple others simultaneously. Second, cells comprise a myriad of different\ncomponents that form various droplets. Such multicomponent phase separation has\nbeen studied in the simple case of pairwise interactions, but an analysis of\nhigher-order interactions is lacking. We propose such a theory and study the\ncorresponding phase diagrams numerically. We find that interactions between\nthree components are similar to pairwise interactions, whereas\ncomposition-dependent higher-order interactions between two components can\noppose phase separation. This surprising result can only be revealed from the\nequilibrium phase diagrams, implying that the often-used stability analysis of\nhomogeneous states is inadequate to study these systems. We thus show that\nhigher-order interactions could play a crucial role in forming droplets in\ncells, and their manipulation could offer novel approaches to controlling\nmulticomponent phase separation.",
        "positive": "Driven translocation of a polymer: fluctuations at work: The impact of thermal fluctuations on the translocation dynamics of a polymer\nchain driven through a narrow pore has been investigated theoretically and by\nmeans of extensive Molecular-Dynamics (MD) simulation. The theoretical\nconsideration is based on the so-called velocity Langevin (V-Langevin) equation\nwhich determines the progress of the translocation in terms of the number of\npolymer segments, $s(t)$, that have passed through the pore at time $t$ due to\na driving force $f$. The formalism is based only on the assumption that, due to\nthermal fluctuations, the translocation velocity $v=\\dot{s}(t)$ is a Gaussian\nrandom process as suggested by our MD data. With this in mind we have derived\nthe corresponding Fokker-Planck equation (FPE) which has a nonlinear drift term\nand diffusion term with a {\\em time-dependent} diffusion coefficient $D(t)$.\nOur MD simulation reveals that the driven translocation process follows a {\\em\nsuper}diffusive law with a running diffusion coefficient $D(t) \\propto\nt^{\\gamma}$ where $\\gamma < 1$. This finding is then used in the numerical\nsolution of the FPE which yields an important result: for comparatively small\ndriving forces fluctuations facilitate the translocation dynamics. As a\nconsequence, the exponent $\\alpha$ which describes the scaling of the mean\ntranslocation time $<\\tau>$ with the length $N$ of the polymer, $<\\tau> \\propto\nN^{\\alpha}$ is found to diminish. Thus, taking thermal fluctuations into\naccount, one can explain the systematic discrepancy between theoretically\npredicted duration of a driven translocation process, considered usually as a\ndeterministic event, and measurements in computer simulations. In the\nnon-driven case, $f=0$, the translocation is slightly subdiffusive and can be\ntreated within the framework of fractional Brownian motion (fBm)."
    },
    {
        "anchor": "Guiding catalytically active particles with chemically patterned\n  surfaces: Catalytically active Janus particles suspended in solution create gradients\nin the chemical composition of the solution along their surfaces, as well as\nalong any nearby container walls. The former leads to self-phoresis, while the\nlatter gives rise to chemi-osmosis, providing an additional contribution to\nself-motility. Chemi-osmosis strongly depends on the molecular interactions\nbetween the diffusing chemical species and the wall. We show analytically,\nusing an approximate \"point-particle\" approach, that by chemically patterning a\nplanar substrate one can direct the motion of Janus particles: the induced\nchemi-osmotic flows can cause particles to either \"dock\" at the chemical step\nbetween the two materials, or to follow a chemical stripe. These theoretical\npredictions are confirmed by full numerical calculations. Generically, docking\noccurs for particles which tend to move away from their catalytic caps, while\nstripe-following occurs in the opposite case. Our analysis reveals the physical\nmechanisms governing this behavior.",
        "positive": "Absolute Measurement Of Laminar Shear Rate Using Photon Correlation\n  Spectroscopy: An absolute measurement of the components of the shear rate tensor\n$\\mathcal{S}$ in a fluid can be found by measuring the photon correlation\nfunction of light scattered from particles in the fluid. Previous methods of\nmeasuring $\\mathcal{S}$ involve reading the velocity at various points and\nextrapolating the shear, which can be time consuming and is limited in its\nability to examine small spatial scale or short time events. Previous work in\nPhoton Correlation Spectroscopy has involved only approximate solutions,\nrequiring free parameters to be scaled by a known case, or different cases,\nsuch as 2-D flows, but here we present a treatment that provides quantitative\nresults directly and without calibration for full 3-D flow. We demonstrate this\ntreatment experimentally with a cone and plate rheometer."
    },
    {
        "anchor": "Impact of Softness of Particles on Rheology of Dilute Granular Gases: We numerically and theoretically investigate how the softness of particles\naffects the rheology of sheared dilute granular gases. We find that the kinetic\ntheory predicts the deviation of the flow curve from the Bagnold scaling, and\nit works well below a certain shear rate when we compare with the simulation\nresults. It is also found that there is no theoretical solution above this\nshear rate, which is because the energy loss due to inelastic collisions cannot\nbe balanced with the energy injection by the shear.",
        "positive": "Statistical theory of elastic constants of cholesteric liquid crystals: A statistical theory of cholesteric liquid crystals composed of short rigid\nbiaxial molecules is presented. It is derived in the thermodynamic limit at a\nsmall density and a small twist. The uniaxial (biaxial) cholesteric phase is\nregarded as a distorted form of the uniaxial (biaxial) nematic phase. The\nchirality of the interactions and the implementation of the inversion to the\nrotation matrix elements are discussed in detail. General microscopic\nexpressions for the elastic constants are derived. The expressions involve the\none-particle distribution function and the potential energy of two-body\nshort-range interactions. It is shown that the elastic constants determine the\ntwist of the phase. The stability condition for the cholesteric and nematic\nphases is presented. The theory is used to study unary and binary systems. The\ntemperature and concentration dependence of the order parameters, the elastic\nconstants and the twist of the phase are obtained. The possibility of phase\nseparation is not investigated."
    },
    {
        "anchor": "Polymer compaction and bridging-induced clustering of protein-inspired\n  patchy particles: There are many proteins or protein complexes which have multiple DNA binding\ndomains. This allows them to bind to multiple points on a DNA molecule (or\nchromatin fibre) at the same time. There are also many proteins which have been\nfound to be able to compact DNA in vitro, and many others have been observed in\nfoci or puncta when fluorescently labelled and imaged in vivo. In this work we\nstudy, using coarse-grained Langevin dynamics simulations, the compaction of\npolymers by simple model proteins and a phenomenon known as the\n\"bridging-induced attraction\". The latter is a mechanism observed in previous\nsimulations [Brackley et al., Proc. Natl. Acad. Sci. USA 110 (2013)], where\nproteins modelled as spheres form clusters via their multivalent interactions\nwith a polymer, even in the absence of any explicit protein-protein attractive\ninteractions. Here we extend this concept to consider more detailed model\nproteins, represented as simple \"patchy particles\" interacting with a\nsemi-flexible bead-and-spring polymer. We find that both the compacting ability\nand the effect of the bridging-induced attraction depend on the valence of the\nmodel proteins. These effects also depend on the shape of the protein, which\ndetermines its ability to form bridges.",
        "positive": "Understanding the Unusual Properties of Water: Water is commonly associated to the existence of life. However, there is no\nclear reason why water should be the only liquid in which life could form and\nsurvive. Since the seminal work of L. J. Henderson in 1913, scientists are\ntrying to answer the question about the relation between the unusual properties\nof water and the existence of life. Here we follow the first steps along the\nchallenging path to this answer, trying to understand (i) what is unusual about\nwater; (ii) why water has anomalies; (iii) which are the full implications of\nthese unusual properties; and (iv) if these anomalies are exclusive properties\nof water. By identifying some interesting clues, then by formulating a working\nhypothesis and, next, by testing it, we find the surprising results that some\nproperties of water, such as the anomalous behavior of density, are very\nsensitive to small changes of the microscopic interactions, while others, such\nas the presence of more than one crystal or a possible phase transition between\ntwo liquids with different local structures, are predicted not only in water,\nbut also in other liquids. Since the change of local liquid structure could be\nrelevant in biological processes, the possibility of a wide class of liquids\nwith this property could help in understanding if water is essential for life."
    },
    {
        "anchor": "Theory of anomalous collective diffusion in colloidal monolayers on a\n  spherical interface: A planar colloidal monolayer exhibits anomalous collective diffusion due to\nthe hydrodynamic interactions. We investigate how this behavior is affected by\nthe curvature of the monolayer when it resides on the interface of a spherical\ndroplet. It is found that the characteristic times of the dynamics still\nexhibit the same anomalous scaling as in the planar case. The spatial\ndistribution, however, shows a difference due to the relevance of the radius of\nthe droplet. Since for the droplet this is both a global magnitude, i.e.,\npertaining the spatial extent of the spherical surface, and a local one, i.e.,\nthe radius of curvature, the question remains open as to which of these two\nfeatures actually dominates in the case of a generically curved interface.",
        "positive": "Force balance in canonical ensembles of static granular packings: We investigate the role of local force balance in the transition from a\nmicrocanonical ensemble of static granular packings, characterized by an\ninvariant stress, to a canonical ensemble. Packings in two dimensions admit a\nreciprocal tiling, and a collective effect of force balance is that the area of\nthis tiling is also invariant in a microcanonical ensemble. We present\nanalytical relations between stress, tiling area and tiling area fluctuations,\nand show that a canonical ensemble can be characterized by an intensive\nthermodynamic parameter conjugate to one or the other. We test the equivalence\nof different ensembles through the first canonical simulations of the force\nnetwork ensemble, a model system."
    },
    {
        "anchor": "Formation of Polymorphic Cluster Phases for Purely Repulsive Soft\n  Spheres: We present results from density functional theory and computer simulations\nthat unambiguously predict the occurrence of first-order freezing transitions\nfor a large class of ultrasoft model systems into cluster crystals. The\nclusters consist of fully overlapping particles and arise without the existence\nof attractive forces. The number of particles participating in a cluster scales\nlinearly with density, therefore the crystals feature density-independent\nlattice constants. Clustering is accompanied by polymorphic bcc-fcc\ntransitions, with fcc being the stable phase at high densities.",
        "positive": "Universality of shear-banding instability and crystallization in sheared\n  granular fluid: The linear stability analysis of an uniform shear flow of granular materials\nis revisited using several cases of a Navier-Stokes'-level constitutive model\nin which we incorporate the global equation of states for pressure and thermal\nconductivity (which are accurate up-to the maximum packing density $\\nu_{m}$)\nand the shear viscosity is allowed to diverge at a density $\\nu_\\mu$ ($<\n\\nu_{m}$), with all other transport coefficients diverging at $\\nu_{m}$. It is\nshown that the emergence of shear-banding instabilities (for perturbations\nhaving no variation along the streamwise direction), that lead to shear-band\nformation along the gradient direction, depends crucially on the choice of the\nconstitutive model. In the framework of a dense constitutive model that\nincorporates only collisional transport mechanism, it is shown that an accurate\nglobal equation of state for pressure or a viscosity divergence at a lower\ndensity or a stronger viscosity divergence (with other transport coefficients\nbeing given by respective Enskog values that diverge at $\\nu_m$) can induce\nshear-banding instabilities, even though the original dense Enskog model is\nstable to such shear-banding instabilities. For any constitutive model, the\nonset of this shear-banding instability is tied to a {\\it universal} criterion\nin terms of constitutive relations for viscosity and pressure, and the sheared\ngranular flow evolves toward a state of lower \"dynamic\" friction, leading to\nthe shear-induced band formation, as it cannot sustain increasing dynamic\nfriction with increasing density to stay in the homogeneous state. A similar\ncriterion of a lower viscosity or a lower viscous-dissipation is responsible\nfor the shear-banding state in many complex fluids."
    },
    {
        "anchor": "Two-Yukawa fluid at a hard wall: Field theory treatment: We apply a field-theoretical approach to study the structure and\nthermodynamics of a two-Yukawa fluid confined by a hard wall. We derive mean\nfield equations allowing for numerical evaluation of the density profile which\nis compared to analytical estimations. Beyond the mean field approximation,\nanalytical expressions for the free energy, the pressure, and the correlation\nfunction are derived. Subsequently, contributions to the density profile and\nthe adsorption coefficient due to Gaussian fluctuations are found. Both the\nmean field and the fluctuation terms of the density profile are shown to\nsatisfy the contact theorem. We further use the contact theorem to improve the\nGaussian approximation for the density profile based on a better approximation\nfor the bulk pressure. The results obtained are compared to computer simulation\ndata.",
        "positive": "Testing the Wyart-Cates model for non-Brownian shear thickening using\n  bidisperse suspensions: There is a growing consensus that shear thickening of concentrated\ndispersions is driven by the formation of stress-induced frictional contacts.\nThe Wyart-Cates (WC) model of this phenomenon, in which the microphysics of the\ncontacts enters solely via the fraction $f$ of contacts that are frictional,\ncan successfully fit flow curves for suspensions of weakly polydisperse\nspheres. However, its validity for \"real-life\", polydisperse suspensions has\nyet to be seriously tested. By performing systematic simulations on bidisperse\nmixtures of spheres, we show that the WC model applies only in the monodisperse\nlimit and fails when substantial bidispersity is introduced. We trace the\nfailure of the model to its inability to distinguish large-large, large-small\nand small-small frictional contacts. By fitting our data using a polydisperse\nanalogue of $f$ that depends separately on the fraction of each of these\ncontact types, we show that the WC picture of shear thickening is incomplete.\nSystematic experiments on model shear-thickening suspensions corroborate our\nfindings, but highlight important challenges in rigorously testing the WC model\nwith real systems. Our results prompt new questions about the microphysics of\nthickening for both monodisperse and polydisperse systems."
    },
    {
        "anchor": "Water structuring and collagen adsorption at hydrophilic and hydrophobic\n  silicon surfaces: The adsorption of a collagen fragment on both a hydrophobic,\nhydrogen-terminated and a hydrophilic, natively oxidised Si surface is\ninvestigated using all-atom molecular dynamics. While favourable direct\nprotein-surface interactions via localised contact points characterise adhesion\nto the hydrophilic surface, evenly spread surface/molecule contacts and\nstabilisation of the helical structure occurs upon adsorption on the\nhydrophobic surface. In the latter case, we find that adhesion is accompanied\nby a mutual fit between the hydrophilic/hydrophobic pattern within the protein\nand the layered water structure at the solid/liquid interface, which may\nprovide an additional driving force to the classic hydrophobic effect.",
        "positive": "Modified Sonine approximation for granular binary mixtures: We evaluate in this work the hydrodynamic transport coefficients of a\ngranular binary mixture in $d$ dimensions. In order to eliminate the observed\ndisagreement (for strong dissipation) between computer simulations and\npreviously calculated theoretical transport coefficients for a monocomponent\ngas, we obtain explicit expressions of the seven Navier-Stokes transport\ncoefficients with the use of a new Sonine approach in the Chapman-Enskog\ntheory. Our new approach consists in replacing, where appropriate in the\nChapman-Enskog procedure, the Maxwell-Boltzmann distribution weight function\n(used in the standard first Sonine approximation) by the homogeneous cooling\nstate distribution for each species. The rationale for doing this lies in the\nfact that, as it is well known, the non-Maxwellian contributions to the\ndistribution function of the granular mixture become more important in the\nrange of strong dissipation we are interested in. The form of the transport\ncoefficients is quite common in both standard and modified Sonine\napproximations, the distinction appearing in the explicit form of the different\ncollision frequencies associated with the transport coefficients. Additionally,\nwe numerically solve by means of the direct simulation Monte Carlo method the\ninelastic Boltzmann equation to get the diffusion and the shear viscosity\ncoefficients for two and three dimensions. As in the case of a monocomponent\ngas, the modified Sonine approximation improves the estimates of the standard\none, showing again the reliability of this method at strong values of\ndissipation."
    },
    {
        "anchor": "Cloaking Transition of Droplets on Lubricated Brushes: We study the equilibrium properties and the wetting behavior of a simple\nliquid on a polymer brush, with and without presence of lubricant by multibody\nDissipative Particle Dynamics simulations. The lubricant is modelled as a\npolymeric liquid consisting of short chains that are chemically identical to\nthe brush polymers. We investigate the behavior of the brush in terms of the\ngrafting density and the amount of lubricant present. Regarding the wetting\nbehavior, we study a sessile droplet on top of the brush. The droplet consists\nof non-bonded particles that form a dense phase. Our model and choice of\nparameters result in the formation of a wetting ridge and in the cloaking of\nthe droplet by the lubricant, i.e. the lubricant chains creep up onto the\ndroplet and eventually cover its surface completely. Cloaking is a phenomenon\nthat is observed experimentally and is of integral importance to the dynamics\nof sliding droplets. We quantify the cloaking in terms of its thickness, which\nincreases with the amount of lubricant present. The analysis reveals a\nwell-defined transition point where the cloaking sets in. We propose a\nthermodynamic theory to explain this behavior. In addition we investigate the\ndependence of the contact angles on the size of the droplet and the possible\neffect of line tension. We quantify the variation of the contact angle with the\ncurvature of the contact line on a lubricant free brush and find a negative\nvalue for the line tension. Finally we investigate the effect of\ncloaking/lubrication on the contact angles and the wetting ridge. We find that\nlubrication and cloaking reduce the contact angles by a couple of degrees. The\neffect on the wetting ridge is a reduction in the extension of the brush chains\nnear the three phase contact line, an effect that was also observed in\nexperiments of droplets on crosslinked gels.",
        "positive": "Inhomogeneous magnetization in dipolar ferromagnetic liquids: At high densities fluids of strongly dipolar spherical particles exhibit\nspontaneous long-ranged orientational order. Typically, due to demagnetization\neffects induced by the long range of the dipolar interactions, the\nmagnetization structure is spatially inhomogeneous and depends on the shape of\nthe sample. We determine this structure for a cubic sample by the free\nminimization of an appropriate microscopic density functional using simulated\nannealing. We find a vortex structure resembling four domains separated by four\ndomain walls whose thickness increases proportional to the system size L. There\nare indications that for large L the whole configuration scales with the system\nsize. Near the axis of the mainly planar vortex structure the direction of the\nmagnetization escapes into the third dimension or, at higher temperatures, the\nabsolute value of the magnetization is strongly reduced. Thus the orientational\norder is characterized by two point defects at the top and the bottom of the\nsample, respectively. The equilibrium structure in an external field and the\ntransition to a homogeneous magnetization for strong fields are analyzed, too."
    },
    {
        "anchor": "Instability and rupture of sheared viscous liquid nanofilms: Liquid nanofilms are ubiquitous in nature and technology, and their\nequilibrium and out-of-equilibrium dynamics are key to a multitude of phenomena\nand processes. We numerically study the evolution and rupture of viscous\nnanometric films, incorporating the effects of surface tension, van der waals\nforces, thermal fluctuations and viscous shear. We show that thermal\nfluctuations create perturbations that can trigger film rupture, but they do\nnot significantly affect the growth rate of the perturbations. The film rupture\ntime can be predicted from a linear stability analysis of the governing thin\nfilm equation, by considering the most unstable wavelength and the thermal\nroughness. Furthermore, applying a sufficiently large unidirectional shear can\nstabilise large perturbations, creating a finite-amplitude travelling wave\ninstead of film rupture. In contrast, in three dimensions, unidirectional shear\ndoes not inhibit rupture, as perturbations are not suppressed in the direction\nperpendicular to the applied shear. However, if the direction of shear varies\nin time, the growth of large perturbations is prevented in all directions, and\nrupture can hence be impeded.",
        "positive": "Shear instabilities of freely standing thermotropic smectic-A films: In this Letter we discuss theoretically the instabilities of thermotropic\nfreely standing smectic-A films under shear flow\\cite{re:wu}. We show that, in\nCouette geometry, the centrifugal force pushes the liquid crystal toward the\nouter boundary and induces smectic layer dilation close to the outer boundary.\nUnder strong shear, this effect induces a layer buckling instability. The\ncritical shear rate is proportional to $1/\\sqrt{d}$, where $d$ is the thickness\nof the film."
    },
    {
        "anchor": "Extension of the one-dimensional Stoney algorithm to a two-dimensional\n  case: This article presents the extension of the one-dimensional Stoney algorithm\nto a two-dimensional case. The proposed extension consists in modifying the\nmethod of curvature estimation. The surface profile of the wafer before\ndeposition of the thin film and after its deposition was locally approximated\nby the quadric. From this quadric, a quadratic form and the first degree\nsurface were separated. An eigenproblem was solved for the matrix of this\nquadratic form. From eigenvectors a new coordinate system was created in which\na new formula of the quadric was found. In this new coordinate system, the\ntwo-dimensional problem of estimating the curvature tensor has been solved by\nsolving two independent one-dimensional problems of curvature estimation.\nReturning to the primary coordinate system, in this primary coordinate system,\na solution to the two-dimensional problem was obtained. The article proposed\nfive versions of the two-dimensional Stoney algorithm, with diverse complexity\nand accuracy. The recommendation for the version of the algorithm that could be\npractically used was also presented.",
        "positive": "Polymers grafted to porous membranes: We study a single flexible chain molecule grafted to a membrane which has\npores of size slightly larger than the monomer size. On both sides of the\nmembrane there is the same solvent. When this solvent is good, i.e. when the\npolymer is described by a self avoiding walk, it can fairly easily penetrate\nthe membrane, so that the average number of membrane crossings tends, for chain\nlength $N\\to\\infty$, to a positive constant. The average numbers of monomers on\neither side of the membrane diverges in this limit, although their ratio\nbecomes infinite. For a poor solvent, in contrast, the entire polymer is\nlocated, for large $N$, on one side of the membrane. For good and for theta\nsolvents (ideal polymers) we find scaling laws, whose exponents can in the\nlatter case be easily understood from the behaviour of random walks."
    },
    {
        "anchor": "Symmetry, Levitation Effect and Size Dependent Diffusivity Maximum: Diffusion invariably involves motion within a medium. An universal behavior\nobserved is that self diffusivity exhibits a maximum as a function of the size\nof the diffusant when the diffusant is confined to a medium, as a result of\nwhat is known as the Levitation Effect. Such a maximum in self diffusivity has\nbeen seen in widely differing medium : microporous solids, dense liquids and\nclose-packed solids, ions in polar solvents, etc. The effect arises because the\nforces exerted on the diffusant by the medium in which it is confined is a\nminimum for the size of the diffusant for which self diffusivity is a maximum.\nWe report here simulations on a diatomic species confined to the cages of\nzeolite Y. Several different simulations in which the two atoms of the model\ndiatomic species interact with equal strength(example, $O_2$, the symmetric\ncase) and with unequal interaction strengths (example, $CO$, asymmetric case)\nare modeled here. Further, the bond length of the diatomic species is varied.\nOur results for the symmetric case shows that self diffusivity is maximum for a\nlarge enough bond length which fits snugly into the 12-ring window of zeolite\nY. For weakly asymmetric case, a weak maximum is seen as a function of the bond\nlength of the diatomic species. However, for strongly asymmetric case, no\nmaximum in self diffusivity is seen for all the bond lengths studied. This\ndemonstrates close relation between symmetry and the diffusivity maximum and\nprovides a direct evidence for the need of force cancellation to observe the\nLevitation Effect.",
        "positive": "Sociohydrodynamics: data-driven modelling of social behavior: Living systems display complex behaviors driven not only by physical forces,\nbut also decision-making guided by information processing and molded by\ncultural and/or biological evolution. Hydrodynamic theories hold promise for\nsimplified, universal descriptions of these collective behaviors. However,\nincorporating the individual preferences of decision-making organisms into a\nhydrodynamic theory is an open problem. Here, we develop a data-driven pipeline\nthat links micromotives to macrobehavior by augmenting hydrodynamics with\nutility functions that describe individual preferences in microeconomics. We\nshow how to systematically validate the hypotheses underlying this construction\nfrom data using statistical tools based on neural networks. We illustrate this\npipeline on the case study of human residential dynamics in the United States,\nfor which census and sociological data is available, and show how trends in\nsociological surveys can be related to trends seen in racial segregation. In\nparticular, we highlight that a history-dependence in the\nsegregation-integration transition can arise even when agents have no memory.\nBeyond residential segregation, our work paves the way for systematic\ninvestigations of social-driven motility in real space from micro-organisms to\nhumans, as well as fitness-mediated motion in more abstract genomic spaces."
    },
    {
        "anchor": "Study on stability of the first kind of soft-matter quasicrystals: Based on extended free energy of soft-matter quasicrystals and the variation\nprinciple on thermodynamic stability, this study reports the results on\nstability of the first kind of soft-matter quasicrystals. They are dependent\nonly upon the material constants, and quite simple and intuitive, the material\nconstants can be measured by experiments. The results are significant in\nstudying thermodynamics of the matter.",
        "positive": "Quantifying Dynamical Heterogeneity Length Scales of Interface Water\n  across Model Membrane Phase Transition: All-atom molecular dynamics simulations of\n1,2-dimyristoyl-sn-glycerol-3-phosphocholine lipid membranes reveal a membrane\nphase transition dictated drastic growth in the interface water (IW)\nheterogeneity length scales. It acts as an alternate probe to capture the\nripple size of the membrane and follows an activated dynamical scaling with the\nrelaxation time scale solely within the gel phase. The results quantify the\nmostly unknown correlations between the spatio-temporal scales of the IW and\nmembranes at various phases under physiological and supercooled condition"
    },
    {
        "anchor": "Probing the nanohydrodynamics at liquid-solid interfaces using thermal\n  motion: We report on a new method to characterize nano-hydrodynamic properties at the\nliquid/solid interface relying solely on the measurement of the thermal motion\nof confined colloids. Using Fluorescence Correlation Spectroscopy (FCS) to\nprobe the diffusion of the colloidal tracers, this optical technique\n--equivalent in spirit to the microrheology technique used for bulk\nproperties-- is able to achieve nanometric resolution on the slip length\nmeasurement. It confirms the no-slip boundary condition on wetting surfaces and\nshows a partial slip b=18 +/- 5 nm on non-wetting ones. Moreover, in the\nabsence of external forcing, we do not find any evidence for large nano-bubble\npromoted slippage on moderately rough non-wetting surfaces.",
        "positive": "Granular dynamics in auger sampling: From geotechnical applications to space exploration, auger drilling is often\nused as a standard tool for soil sample collection, instrument installation,\nand others. Focusing on granular flow associated with the rotary drilling\nprocess, we investigate the performance of auger drilling in terms of sampling\nefficiency, defined as the mass ratio of the soil sample collected in the\ncoring tube to its total volume at a given penetration depth, by means of\nexperiments, numerical simulations, as well as theoretical analysis. The ratio\nof rotation to penetration speed is found to play a crucial role in the\nsampling process. A continuum model for the coupled granular flow in both\ncoring and discharging channels is proposed to elucidate the physical mechanism\nbehind the sampling process. Supported by a comparison to experimental results,\nthe continuum model provides a practical way to predict the performance of\nauger drilling. Further analysis reveals that the drilling process approaches a\nsteady state with constant granular flow speeds in both channels. In the steady\nstate, sampling efficiency decreases linearly with the growth of the rotation\nto penetration speed ratio, which can be well captured by the analytical\nsolution of the model. The analytical solution also suggests that the sampling\nefficiency is independent of gravity in the steady state, which has profound\nimplications for extraterrestrial sample collection in future space missions."
    },
    {
        "anchor": "Playing with Active Matter: In the last 20 years, active matter has been a very successful research\nfield, bridging the fundamental physics of nonequilibrium thermodynamics with\napplications in robotics, biology, and medicine. This field deals with active\nparticles, which, differently from passive Brownian particles, can harness\nenergy to generate complex motions and emerging behaviors. Most active-matter\nexperiments are performed with microscopic particles and require advanced\nmicrofabrication and microscopy techniques. Here, we propose some macroscopic\nexperiments with active matter employing commercially available toy robots,\ni.e., the Hexbugs. We demonstrate how they can be easily modified to perform\nregular and chiral active Brownian motion. We also show that Hexbugs can\ninteract with passive objects present in their environment and, depending on\ntheir shape, set them in motion and rotation. Furthermore, we show that, by\nintroducing obstacles in the environment, we can sort the robots based on their\nmotility and chirality. Finally, we demonstrate the emergence of Casimir-like\nactivity-induced attraction between planar objects in the presence of active\nparticles in the environment.",
        "positive": "Correct scaling of the correlation length from a theory for concentrated\n  electrolytes: Self-consistent theory for concentrated electrolytes is developed.\nOscillatory decay of the charge-charge correlation function with the decay\nlength that shows perfect agreement with the experimentally discovered and so\nfar unexplained scaling is obtained. For the density-density correlations,\nmonotonic asymptotic decay with the decay length comparable with the decay\nlength of the charge correlations is found. We show that the correlation\nlengths in concentrated electrolytes depend crucially on the local variance of\nthe charge density."
    },
    {
        "anchor": "Defect dynamics in active smectics induced by confining geometry and\n  topology: The persistent dynamics in systems out of equilibrium, particularly those\ncharacterized by annihilation and creation of topological defects, is known to\ninvolve complicated spatiotemporal processes and is deemed difficult to\ncontrol. Here the complex dynamics of defects in active smectic layers exposed\nto strong confinements is explored, through self-propulsion of active particles\nand a variety of confining geometries with different topology, ranging from\ncircular, flower-shaped epicycloid, to hypocycloid cavities, channels, and\nrings. We identify a wealth of dynamical behaviors during the evolution of\ncomplex spatiotemporal defect patterns as induced by the confining shape and\ntopology, particularly a perpetual creation-annihilation dynamical state at\nintermediate activity with large fluctuations of topological defects and a\ncontrollable transition from oscillatory to damped time correlation of defect\nnumber density via mechanisms governed by boundary cusps. Our results are\nobtained by using an active phase field crystal approach. Possible experimental\nrealizations are also discussed.",
        "positive": "Spherically symmetric solvent is sufficient to explain lower critical\n  solution temperature in polymer solutions: We study the lower critical solution temperature (LCST) in thermoresponsive\npolymer solutions by means of a coarse grained single polymer chain simulation\nand a theoretical approach. The simulation model includes solvent explicitly\nand thus accounts for solvent interactions and entropy directly. The\ntheoretical model consists of a single chain polymer in an implicit solvent\nwhere the effect of solvent is included through the intra-polymer solvophobic\npotential proposed by Kolomeisky and Widom. Our results indicate that the LCST\nbehavior is determined by the competition between the mean energy difference\nbetween the bulk and bound solvent, and the entropy loss due to the bound\nsolvent. At low temperatures, solvent molecules are bound to the polymer and\nthe solvophobicity of the polymer is screened, resulting in a coiled state. At\nhigh temperatures the entropy loss due to bound solvent offsets the energy gain\ndue to binding which causes the solvent molecules to unbind, leading to the\ncollapse of the polymer chain to a globular state. Furthermore, the coarse\ngrained nature of these models indicates that mean interaction energies are\nsufficient to explain LCST in comparison to specific solvent structural\narrangements."
    },
    {
        "anchor": "Deformation and chaining of flexible shells in a nematic solvent: A micrometer-scale elastic shell immersed in a nematic liquid crystal may be\ndeformed by the host if the cost of deformation is comparable to the cost of\nelastic deformation of the nematic. Moreover, such inclusions interact and form\nchains due to quadrupolar distortions induced in the host. A continuum theory\nmodel using finite elements is developed for this system, using mesh\nregularization and dynamic refinement to ensure quality of the numerical\nrepresentation even for large deformations. From this model, we determine the\ninfluence of the shell elasticity, nematic elasticity and anchoring condition\non the shape of the shell and hence extract parameter values from an\nexperimental realization. Extending the model to multi-body interactions, we\npredict the alignment angle of the chain with respect to the host nematic as a\nfunction of aspect ratio, which is found to be in excellent agreement with\nexperiments and greatly improves upon previous theoretical predictions.",
        "positive": "Wetting in mixtures of colloids and excluded-volume polymers from\n  density functional theory: We use a microscopic density functional theory based on Wertheim's first\norder thermodynamic perturbation theory to study wetting behavior of athermal\nmixtures of colloids and excluded-volume polymers. In opposition to the wetting\nbehavior of the Asakura-Oosawa-Vrij model we find the polymer-rich phase to wet\na hard wall. The wetting transition is of the first order and is accompanied by\nthe prewetting transition. We do not find any hints for the layering\ntransitions in the partial wetting regime. Our results resemble the wetting\nbehavior in athermal polymer solutions. We point out that an accurate,\nmonomer-resolved theory for colloid-polymer mixtures should incorporate the\ncorrect scaling behavior in the dilute polymer regime and an accurate\ndescription of the reference system."
    },
    {
        "anchor": "Quantum transport through a DNA wire in a dissipative environment: Electronic transport through DNA wires in the presence of a strong\ndissipative environment is investigated. We show that new bath-induced\nelectronic states are formed within the bandgap. These states show up in the\nlinear conductance spectrum as a temperature dependent background and lead to a\ncrossover from tunneling to thermal activated behavior with increasing\ntemperature. Depending on the strength of the electron-bath coupling, the\nconductance at the Fermi level can show a weak exponential or even an algebraic\nlength dependence. Our results suggest a new environmental-induced transport\nmechanism. This might be relevant for the understanding of molecular conduction\nexperiments in liquid solution, like those recently performed on poly(GC)\noligomers in a water buffer (B. Xu et al., Nano Lett 4, 1105 (2004)).",
        "positive": "Non-affinity of liquid networks and bicontinuous mesophases: Amphiphiles self-assemble into a variety of bicontinuous mesophases whose\nequilibrium structures take the form of high-symmetry cubic networks. Here, we\nshow that the symmetry-breaking distortions in these systems give rise to\nanomalously large, non-affine collective deformations, which we argue to be a\ngeneric consequence of mass equilibration within deformed networks. We propose\nand study a minimal liquid network model of bicontinuous networks, in which\nacubic distortions are modeled by the relaxation of residually-stressed\nmechanical networks with constant-tension bonds. We show that non-affinity is\nstrongly dependent on the valency of the network as well as the degree of\nstrain-softening/stiffening force in the bonds. Taking diblock copolymer melts\nas a model system, liquid network theory captures quantitative features of two\nbicontinuous phases based on comparison with self-consistent field theory\npredictions and direct experimental characterization of acubic distortions,\nwhich are likely to be pronounced in soft amphiphilic systems more generally."
    },
    {
        "anchor": "Membrane tension feedback on shape and motility of eukaryotic cells: In the framework of a phase field model of a single cell crawling on a\nsubstrate, we investigate how the properties of the cell membrane affect the\nshape and motility of the cell. Since the membrane influences the cell dynamics\non multiple levels and provides a nontrivial feedback, we consider the\nfollowing fundamental interactions: (i) the reduction of the actin\npolymerization rate by membrane tension; (ii) area conservation of the cell's\ntwo-dimensional cross-section vs. conservation of its circumference (i.e.\nmembrane inextensibility); and (iii) the contribution from the membrane's\nbending energy to the shape and integrity of the cell. As in experiments, we\ninvestigate two pertinent observables -- the cell's velocity and its aspect\nratio. We find that the most important effect is the feedback of membrane\ntension on the actin polymerization. Bending rigidity has only minor effects,\nvisible mostly in dynamic reshaping events, as exemplified by collisions of the\ncell with an obstacle.",
        "positive": "Simple Model of Splitting Instability in Swollen Membranes: A simple one-dimensional mechanical model is proposed for splitting\ninstability in swollen membranes. The splitting instability occurs by ring\nconstriction. The bifurcation can be both subcritical and supercritical,\ndepending on the slenderness of spheroidal membranes. The lower critical point\nis estimated theoretically for the simplest circular system. Necking\ninstability occurs in a spheroidal membrane when the twist angle in the\nboundary conditions is increased."
    },
    {
        "anchor": "Theory of the center-of-mass diffusion and viscosity of microstructured\n  and variable sequence copolymer liquids: Biomolecular condensates formed through the phase separation of proteins and\nnucleic acids are widely observed, offering a fundamental means of organizing\nintracellular materials in a membrane-less fashion. Traditionally, these\ncondensates have been regarded as homogeneous isotropic liquids. However, in\nanalogy with some synthetic copolymer systems, our recent theoretical research\nhas demonstrated that model biomolecular condensates can exhibit a\nmicroemulsion-like internal structure, contingent upon the specific sequence,\ninter-chain site-site interactions, and concentrated phase polymer density. In\nthis study, we present a microscopic dynamical theory for the self-diffusion\nconstant and viscosity of concentrated unentangled A/B regular multiblock\ncopolymer solutions. Our approach integrates static equilibrium local and\nmicrodomain scale structural information obtained from PRISM integral equation\ntheory and the time evolution of the autocorrelation function of monomer scale\nforces at the center-of-mass level that determine the polymer diffusion\nconstant and viscosity in a weak caging regime far from a glass or gel\ntransition. We focus on regular multi-block systems both for simplicity and for\nits relevance to synthetic macromolecular science. The impact of sequence and\ninter-chain attraction strength on the slowing down of copolymer mass transport\nand flow due to local clustering enhanced collisional friction and retardation\nof motion due to emergent microdomain scale ordering are established. Analytic\nanalysis and metrics employed in the study of biomolecular condensates are\nemployed to identify key order parameters that quantity how attractive forces,\npacking structure, multiblock sequence, and copolymer density determine\ndynamical slowing down above and below the crossover to a fluctuating polymeric\nmicroemulsion state.",
        "positive": "Connecting microscopic and mesoscopic mechanics in model structural\n  glasses: We present a novel formalism to characterize elastic heterogeneities in\namorphous solids. In particular, we derive high-order strain-energy expansions\nfor pairwise energies under athermal quasistatic dynamics. We then use the\npresented formalism to study the statistical properties of pairwise expansion\ncoefficients and their link with the statistics of soft, quasilocalized modes,\nfor a wide range of formation histories in both two- and three-dimensional\nsystems. We further exploit the presented framework to access local yield\nstress maps by performing a non-linear stress-strain expansion within a cavity\nembedded in a frozen matrix. We show that our \"bond micromechanics\" compare\nwell with the original \"frozen matrix\" method, with the caveat of\noverestimating large stress activations. We additionally show how local yield\nrules can be used as input for a scalar elasto-plastic model (EPM) to predict\nthe stress response of materials ranging from ductile to brittle. Finally, we\nhighlight some of the limits of simple mesoscale models in capturing the aging\ndynamics of post-yielding systems. Intriguingly, we observe subdiffusive and\ndiffusive shearband growths for particle-based simulations and EPMs,\nrespectively."
    },
    {
        "anchor": "Microscopic origins of the viscosity of a Lennard-Jones liquid: Unlike crystalline solids or ideal gases, transport properties remain\ndifficult to describe from a microscopic point of view in liquids, whose\ndynamics result from complex energetic and entropic contributions at the atomic\nscale. Two scenarios are generally proposed: one represents the dynamics in a\nfluid as a series of energy barrier crossings, leading to Arrhenius-like laws,\nwhile the other assumes that atoms rearrange themselves by collisions, as\nexemplified by the free volume model. To assess the validity of these two\nviews, we computed, using molecular dynamics simulations, the transport\nproperties of the Lennard-Jones fluid and tested to what extent the Arrhenius\nequation and the free volume model describe the temperature dependence of the\nviscosity and of the diffusion coefficient at fixed pressure. Although both\nmodels reproduce the simulation results over a wide range of pressure and\ntemperature covering the liquid and supercritical states of the Lennard-Jones\nfluid, we found that the parameters of the free volume model can be estimated\ndirectly from local structural parameters, also obtained in the simulations.\nThis consistency of the results gives more credibility to the free volume\ndescription of transport properties in liquids.",
        "positive": "Axisymmetric necking of a circular electrodes-coated dielectric membrane: We investigate the stability of a circular electrodes-coated dielectric\nmembrane under the combined action of an electric field and all-round in-plane\ntension. It is known that such a membrane is susceptible to the limiting point\ninstability (also known as pull-in instability) which is widely believed to be\na precursor to electric breakdown. However, there is experimental evidence\nshowing that the limiting point instability may not necessarily be responsible\nfor rapid thinning and electric breakdown. We explore the possibility that the\nlatter is due to a new instability mechanism, namely localised axisymmetric\nnecking. The bifurcation condition for axisymmetric necking is first derived\nand used to show that this instability may occur before the Treloar-Kearsley\ninstability or the limiting point instability for a class of free energy\nfunctions. A weakly nonlinear analysis is then conducted and it is shown that\nthe near-critical behavior is described by a fourth order nonlinear ODE with\nvariable coefficients. This amplitude equation is solved using the finite\ndifference method and it is demonstrated that a localised solution does indeed\nbifurcate from the homogeneous solution. Based on this analysis and what is\nalready known for the purely mechanical case, we may deduce that the necking\nevolution follows the same three stages of initiation, growth and propagation\nas other similar localisation problems. The insight provided by the current\nstudy is expected to be relevant in assessing the integrity of dielectric\nelastomer actuators."
    },
    {
        "anchor": "Physical properties of liquid oxygen under ultrahigh magnetic fields: We studied the acoustic properties of liquid oxygen up to 90 T by means of\nultrasound measurements. We observed a monotonic decrease of the sound velocity\nand an asymptotic increase of the sound attenuation when applying magnetic\nfields. The unusual attenuation, twenty times as large as the zero-field value,\nsuggests strong fluctuations of the local molecular arrangement. We point out\nthat the observed fluctuations are related to a liquid-liquid transition or\ncrossover, from a small-magnetization to a large-magnetization liquid, which is\ncharacterized by a local-structure rearrangement. To investigate higher-field\nproperties of liquid oxygen, we performed single-turn-coil experiments up to\n180 T by means of the acoustic, dilatometric, magnetic, and optical techniques.\nWe observed only monotonic changes of these properties, reflecting the absence\nof the proposed liquid-liquid transition in our experimental conditions.",
        "positive": "Crack-front model for adhesion of soft elastic spheres with chemical\n  heterogeneity: Adhesion hysteresis can be caused by elastic instabilities that are triggered\nby surface roughness or chemical heterogeneity. However, the role of these\ninstabilities in adhesion hysteresis remains poorly understood because we lack\ntheoretical and numerical models accounting for realistic roughness. Our work\nfocuses on the adhesion of soft elastic spheres with low roughness or weak\nheterogeneity, where the indentation process can be described as a\nGriffith-like propagation of a nearly circular external crack. We discuss how\nto describe the contact of spheres with chemical heterogeneity that leads to\nfluctuations in the local work of adhesion. We introduce a variational\nfirst-order crack-perturbation model and validate our approach using\nboundary-element simulations. The crack-perturbation model faithfully predicts\ncontact shapes and hysteretic force-penetration curves, provided that the\ncontact perimeter remains close to a circle and the contact area is simply\nconnected. Computationally, the crack-perturbation model is orders of magnitude\nmore efficient than the corresponding boundary element formulation, allowing\nfor realistic heterogeneity fields. Furthermore, our crack-front formulation\nclarifies the connection of adhesion hysteresis to classic theories on pinning\nof elastic lines."
    },
    {
        "anchor": "Intrinsic Geometry and Director Reconstruction for Three-Dimensional\n  Liquid Crystals: We give a description of the intrinsic geometry of elastic distortions in\nthree-dimensional nematic liquid crystals and establish necessary and\nsufficient conditions for a set of functions to represent these distortions by\ndescribing how they couple to the curvature tensor. We demonstrate that, in\ncontrast to the situation in two dimensions, the first-order gradients of the\ndirector alone are not sufficient for full reconstruction of the director field\nfrom its intrinsic geometry: it is necessary to provide additional information\nabout the second-order director gradients. We describe several different\nmethods by which the director field may be reconstructed from its intrinsic\ngeometry. Finally, we discuss the coupling between individual distortions and\ncurvature from the perspective of Lie algebras and groups and describe\nhomogeneous spaces on which pure modes of distortion can be realised.",
        "positive": "Rigidity transitions in zero-temperature polygons: We study geometrical clues of a rigidity transition due to the emergence of a\nsystem-spanning state of self stress in under-constrained systems of individual\npolygons and spring networks constructed from such polygons. When a polygon\nwith harmonic bond edges and an area spring constraint is subject to an\nexpansive strain, we observe that convexity of the polygon is a necessary\ncondition for such a self stress. We prove that the cyclic configuration of the\npolygon is a sufficient condition for the self stress. This correspondence of\ngeometry and rigidity is akin to the straightening of a one dimensional chain\nof springs to rigidify it. We predict the onset of the rigidity transition\nusing a purely geometrical method. We also estimate the transition strain for a\ngiven initial configuration by approximating irregular polygons as regular\npolygons. These findings help determine the rigidity of an area-preserving\npolygon just by looking at it. Since two-dimensional spring networks can be\nconsidered as a network of polygons, we look for similar geometric features in\nunder-constrained spring networks under isotropic expansive strain. In\nparticular, we observe that all polygons attain convexity at the rigidity\ntransition such that the fraction of convex, but not cyclic, polygons predicts\nthe onset of the rigidity transition. Interestingly, acyclic polygons in the\nnetwork correlate with larger tensions, thus, forming effective force chains."
    },
    {
        "anchor": "Aggregation and Segregation of Confined Active Particles: We simulate a model of self-propelled disks with soft repulsive interactions\nconfined to a box in two dimensions. For small rotational diffusion rates,\nmonodisperse disks spontaneously accumulate at the walls. At low densities,\ninteraction forces between particles are strongly inhomogeneous, and a simple\nmodel predicts how these inhomogeneities alter the equation of state. At higher\ndensities, collective effects become important. We observe signatures of a\njamming transition at a packing fraction $\\phi \\sim 0.88$, which is also the\njamming point for non-active athermal monodisperse disks. At this $\\phi$, the\nsystem develops a critical finite active speed necessary for wall aggregation.\nAt packing fractions above $\\phi \\sim 0.6$, the pressure decreases with\nincreasing density, suggesting that strong interactions between particles are\naffecting the equation of state well below the jamming transition. A mixture of\nbidisperse disks segregates in the absence of any adhesion, identifying a new\nmechanism that could contribute to cell sorting in embryonic development.",
        "positive": "Intermittency and non-Gaussian fluctuations in the dynamics of aging\n  colloidal gels: This paper has been temporarily withdrawn by the authors. We have recently\nfound that noise in the experiments is at the origin of the supposed\n\"back-and-forth\" motion which is discussed in the first version of the paper.\nAs a consequence, figs 4 and 5 as well as their discussion are incorrect.\nFigure 1 and the general trend of fig. 2 are still valid. At this time, we are\nuncertain whether or not the short time behavior of cI, shown in fig. 3, is\naffected by measurement noise. We are working on a new version of the paper,\nusing new techniques that allow us to correct for the experimental noise."
    },
    {
        "anchor": "A mathematical approach to mechanical properties of networks in\n  thermoplastic elastomers: We employ a mathematical model to analyze stress chains in thermoplastic\nelastomers (TPEs) with a microphase-separated spherical structure composed of\ntriblock copolymers. The model represents stress chains during uniaxial and\nbiaxial extensions using networks of spherical domains connected by bridges. We\nadvance previous research and discuss permanent strain and other aspects of the\nnetwork. It explores the dependency of permanent strain on the extension\ndirection, using the average of tension tensors to represent isotropic material\nbehavior. The concept of deviation angle is introduced to measure network\nanisotropy and is shown to play an essential role in predicting permanent\nstrain when a network is extended in a specific direction. The paper also\ndiscusses methods to create a new network structure using various polymers.",
        "positive": "Time-Dependent Trapping of Solitons in Bose-Einstein Condensates: We study the influence of a time-dependent potential on the motion of\nsolitons in a quasi one-dimensional Bose-Einstein condensate by solving the\ncorresponding Gross-Pitaevskii equation. For a suitable choice of the external\npotentials as well as the initial soliton characteristics time-dependent\ntrapping of the soliton in a prescribed subarea of the condensate can be\nachieved. Adiabatic perturbation theory is shown to work remarkably well for\nlarge switching on times of the trapping potential and allows to perform a\ndetailed study of the degree of trapping in the complete phase space of the\nsoliton center. A remarkable spiral pattern of the degree of trapping as a\nfunction of the soliton characteristics is observed and explained."
    },
    {
        "anchor": "Morphological computation and decentralized learning in a swarm of\n  sterically interacting robots: Whereas naturally occurring swarms thrive when crowded, physical interactions\nin robotic swarms are either avoided or carefully controlled, thus limiting\ntheir operational density. Here we present a mechanical design rule that allows\nrobots to act in a collision-dominated environment. We introduce the Morphobots\n-- a robotic swarm platform developed to implement embodied computation through\na morpho-functional design. By engineering a 3D-printed exoskeleton we encode a\nre-orientation response to an external body force (such as gravity) or a\nsurface force (such as a collision). We show that the force-orientation\nresponse is generic, and can augment existing swarm-robotic platforms (e.g\nKilobots) as well as custom robots even 10 times larger. At the individual\nlevel, the exoskeleton improves the motility and stability, and also allows to\nencode two contrasting dynamical behaviors in response to an external force or\na collision (including collision with a wall or a movable obstacle, and on a\ndynamically tilting plane). This force-orientation response adds a mechanical\nlayer to the robot's sense-act cycle at the swarm level, leveraging steric\ninteractions for collective phototaxis when crowded. Enabling collisions also\npromotes information flow, facilitating online distributed learning. Each robot\nruns an embedded algorithm that ultimately optimizes collective performance. We\nidentify an effective parameter that controls the force-orientation response\nand explore its implications in swarms that transition from dilute to crowded.\n\\green{Experimenting with both physical swarms (of up to 64 robots), and\nsimulated swarms (of up to 8192 agents) show that the effect of\nmorphological-computation increases with growing swarm size.",
        "positive": "Morphological Thermodynamics of Fluids: Shape Dependence of Free\n  Energies: We examine the dependence of a thermodynamic potential of a fluid on the\ngeometry of its container. If motion invariance, continuity, and additivity of\nthe potential are fulfilled, only four morphometric measures are needed to\ndescribe fully the influence of an arbitrarily shaped container on the fluid.\nThese three constraints can be understood as a more precise definition for the\nconventional term \"extensive\" and have as a consequence that the surface\ntension and other thermodynamic quantities contain, beside a constant term,\nonly contributions linear in the mean and Gaussian curvature of the container\nand not an infinite number of curvatures as generally assumed before. We verify\nthis numerically in the entropic system of hard spheres bounded by a curved\nwall."
    },
    {
        "anchor": "Towards an assessment of the accuracy of density functional theory for\n  first principles simulations of water II: A series of 20 ps ab initio molecular dynamic simulations of water at ambient\ndensity and temperatures ranging from 300 to 450K are presented. Both\nCar-Parrinello (CP) and Born-Oppenheimer (BO) molecular dynamics techniques are\ncompared for systems containing 54 and 64 water molecules. At 300K, excellent\nagreement is found between radial distribution functions (RDFs) obtained with\nBO and CP dynamics, provided an appropriately small value of the fictitious\nmass parameter is used in the CP simulation. However, we find that the\ndiffusion coefficients computed from CP dynamics are approximately two times\nlarger than the corresponding BO simulations for T>400K, where statistically\nmeaningful comparisons can be made. Overall, both BO and CP dynamics at 300 K\nyield overstructured RDFs and slow diffusion as compared to experiment. In\norder to understand these discrepancies, the effect of proton quantum motion is\nconsidered with the use of empirical interaction potentials. We find strong\nevidence that proton quantum effects may have a larger impact than previously\nthought on structure and diffusion of the liquid.",
        "positive": "Evaluation of bistable systems versus matched filters in detecting\n  bipolar pulse signals: This paper presents a thorough evaluation of a bistable system versus a\nmatched filter in detecting bipolar pulse signals. The detectability of the\nbistable system can be optimized by adding noise, i.e. the stochastic resonance\n(SR) phenomenon. This SR effect is also demonstrated by approximate statistical\ndetection theory of the bistable system and corresponding numerical\nsimulations. Furthermore, the performance comparison results between the\nbistable system and the matched filter show that (a) the bistable system is\nmore robust than the matched filter in detecting signals with disturbed pulse\nrates, and (b) the bistable system approaches the performance of the matched\nfilter in detecting unknown arrival times of received signals, with an\nespecially better computational efficiency. These significant results verify\nthe potential applicability of the bistable system in signal detection field."
    },
    {
        "anchor": "Entangled Dynamics of a Stiff Polymer: Entangled networks of stiff biopolymers exhibit complex dynamic response,\nemerging from the topological constraints that neighboring filaments impose\nupon each other. We propose a class of reference models for entanglement\ndynamics of stiff polymers and provide a quantitative foundation of the tube\nconcept for stiff polymers. For an infinitely thin needle exploring a planar\ncourse of point obstacles, we have performed large-scale computer simulations\nproving the conjectured scaling relations from the fast transverse\nequilibration to the slowest process of orientational relaxation. We determine\nthe rotational diffusion coefficient of the tracer, its angular confinement,\nthe tube diameter and the orientational correlation functions.",
        "positive": "Rheology of dense granular flows for elongated particles: We study the rheology of dense granular flows for frictionless\nspherocylinders by means of 3D numerical simulations. As in the case of\nspherical particles, the effective friction $\\mu$ is an increasing function of\nthe inertial number $I$, and we systematically investigate the dependence of\n$\\mu$ on the particle aspect ratio $Q$, as well as that of the normal stress\ndifferences, the volume fraction and the coordination number. We show in\nparticular that the quasi-static friction coefficient is non-monotonic with\n$Q$: from the spherical case $Q=1$, it first sharply increases, reaches a\nmaximum around $Q \\simeq 1.05$, and then gently decreases, reaching back its\ninitial value for $Q \\simeq 2$. We provide a microscopic interpretation for\nthis unexpected behavior through the analysis of the distribution of\ndissipative contacts around the particles: as compared to spheres, slightly\nelongated grains enhance contacts in their central cylindrical band, whereas at\nlarger aspect ratios particles tend to align and dissipate by preferential\ncontacts at their hemispherical caps."
    },
    {
        "anchor": "On the Modulational Instability of the Nonlinear Schr\u00f6dinger Equation\n  with Dissipation: The modulational instability of spatially uniform states in the nonlinear\nSchr\\\"odinger equation is examined in the presence of higher-order dissipation.\nThe study is motivated by results on the effects of three-body recombination in\nBose-Einstein condensates, as well as by the important recent work of Segur et\nal. on the effects of linear damping in NLS settings. We show how the presence\nof even the weakest possible dissipation suppresses the instability on a longer\ntime scale. However, on a shorter scale, the instability growth may take place,\nand a corresponding generalization of the MI criterion is developed. The\nanalytical results are corroborated by numerical simulations. The method is\nvalid for any power-law dissipation form, including the constant dissipation as\na special case.",
        "positive": "Stiff Quantum Polymers: At ultralow temperatures, polymers exhibit quantum behavior, which is\ncalculated here for the moments <R^2> and <R^4> of the end-to-end distribution\nin the large-stiffness regime. The result should be measurable for polymers in\nwide optical traps."
    },
    {
        "anchor": "Patterns that persist: Heritable information in stochastic dynamics: Life on earth is distinguished by long-lived correlations in time. The\npatterns of material organization that characterize living organisms today are\ncontingent on events that occurred billions of years ago. This contingency is a\nnecessary component of Darwinian evolution: patterns in the present inherit\nsome of their features from those in the past. Despite its central role in\nbiology, heritable information is difficult to recognize in prebiotic systems\ndescribed in the language of chemistry or physics. Here, we consider one such\ndescription based on continuous-time Markov processes and investigate the\npersistence of heritable information within large sets of dynamical systems.\nWhile the microscopic state of each system fluctuates incessantly, there exist\nfew systems that relax slowly to their stationary distribution over much longer\ntimes. These systems, selected for their persistence, are further distinguished\nby their mesoscopic organization, which allows for accurate course grained\ndescriptions of their dynamics at long times. The slow relaxation of these\nstable patterns is made possible by dissipative currents fueled by\nthermodynamic gradients present in the surrounding reservoirs. We show how the\nrate of entropy production within a system sets an upper bound on the lifetime\nof its persistent patterns. We also consider the probability of finding\npersistence within large sets of dynamical systems. We show that physical\nconstraints based on continuity and locality can strongly influence the\nprobability of persistence and its dependence on system size. Finally, we\ndescribe how heritable information can be quantified in practice using\nuniversal compression algorithms. We demonstrate this approach on an\nexperimental system of magnetically-driven, colloidal rollers and discuss the\napplication of these methods to origins of life research.",
        "positive": "Anomalous Multipole Expansion: Charge Regulation of Patchy,\n  Inhomogeneously Charged Spherical Particles: Charge regulation is an important aspect of electrostatics in biological and\ncolloidal systems, where the charges are generally not fixed, but depend on the\nenvironmental variables. Here, we analyze the charge regulation mechanism in\npatchy, inhomogeneously charged spherical particles, such as globular proteins,\ncolloids, or viruses. Together with the multipole expansion of inhomogeneously\ncharged spherical surfaces, the charge regulation mechanism on the level of\nlinear approximation is shown to lead to a mixing between different multipole\nmoments depending on their capacitance -- the response function of the charge\ndistribution with respect to the electrostatic potential. This presents an\nadditional anomalous feature of molecular electrostatics in the presence of\nionic screening. We demonstrate the influence of charge regulation on several\nexamples of inhomogeneously charged spherical particles, showing that it leads\nto significant changes in their multipole moments."
    },
    {
        "anchor": "Three-dimensional shear in granular flow: The evolution of granular shear flow is investigated as a function of height\nin a split-bottom Couette cell. Using particle tracking, magnetic-resonance\nimaging, and large-scale simulations we find a transition in the nature of the\nshear as a characteristic height $H^*$ is exceeded. Below $H^*$ there is a\ncentral stationary core; above $H^*$ we observe the onset of additional axial\nshear associated with torsional failure. Radial and axial shear profiles are\nqualitatively different: the radial extent is wide and increases with height\nwhile the axial width remains narrow and fixed.",
        "positive": "Micellization Thermodynamic Behavior of Gemini Cationic Surfactants.\n  Modeling its Adsorption at Air/Water Interface: Self-assembly structures of gemini surfactants are characterized, among\nothers, for their low CMC. This characteristic could be due to great\nhydrophobic parts in their molecular structures. That availability could imply\ngreat stability of self-assembly structures or monolayers absorbed in an\ninterface. The micellization behavior of two cationic gemini surfactants,\n{\\alpha},{\\omega}-bis(S-alkyl dimethylammonium) alkane bromides, were studied\nby a modelization of dynamic surface tension (DST) experimental data and\nisothermal titration calorimetry (ITC) measurements. The adsorption data at the\nair/water interface was taken through the analysis of the profile changes of a\npendant drop. The thermodynamic characterization of the micellization process\nof the gemini surfactants was carried out using ITC. A model based on the\nFrumkin adsorption isotherm and the Ward-Tordai diffusion equation was\ndeveloped to obtain the characteristic parameters of the adsorption without the\nneed of using the Gibbs adsorption equation. Positive values of lateral\ninteraction show good stability of the adsorbed monolayer. The ITC data were\nanalyzed following a novel protocol based on the identification of the\ndifferent energetic contributions and regimens observed in the titration\nenthalpograms from demicellization processes. The presence of exothermic peaks\nwould explain the low values of CMC."
    },
    {
        "anchor": "Dynamics of particle moving in one dimensional Lorentz lattice gas: We study the dynamics of a particle moving in one-dimensional Lorentz\nlattice-gas where particle performs mainly three different kinds of motion {\\it\nviz} ballistic motion, diffusion and confinement. There are two different types\nof scatterers, {\\it viz} reflector and transmitters, randomly placed in the\nlattice. Reflectors are such that they reverse the particle's velocity\ndirection and transmitters let it pass through. Scatterers also change their\ncharacter with flipping probability $1-\\alpha$, once the particle interacts\nwith a scatterer. Hence the system is defined by two sets of parameters, $r$,\nwhich is the initial density of reflector/transmitter and $\\alpha$. For\n$\\alpha=0$ and $\\alpha=1$ dynamics of the particle is purely deterministic else\nit is probabilistic. In the pure deterministic case dynamics of the particle is\neither propagation in one direction or confined between two near-by reflectors\npresent. For the probabilistic case $\\alpha \\ne 1$ and $\\ne 0$, although the\ndynamics of particle shows anomalous diffusion where dynamics is faster, slower\nand comparable to normal diffusion on the variation of system parameters\n$(\\alpha, r)$, but the asymptotic behaviour of the particle is normal\ndiffusion. We plot the phase diagram for the asymptotic behaviour, in the plane\nof $\\alpha$ and $r$.",
        "positive": "Orientational correlations and the effect of spatial gradients in the\n  equilibrium steady state of hard rods in 2D : A study using\n  deposition-evaporation kinetics: Deposition and evaporation of infinitely thin hard rods (needles) is studied\nin two dimensions using Monte Carlo simulations. The ratio of deposition to\nevaporation rates controls the equilibrium density of rods, and increasing it\nleads to an entropy-driven transition to a nematic phase in which both static\nand dynamical orientational correlation functions decay as power laws, with\nexponents varying continuously with deposition-evaporation rate ratio. Our\nresults for the onset of the power-law phase agree with those for a conserved\nnumber of rods. At a coarse-grained level, the dynamics of the non-conserved\nangle field is described by the Edwards-Wilkinson equation. Predicted relations\nbetween the exponents of the quadrupolar and octupolar correlation functions\nare borne out by our numerical results. We explore the effects of spatial\ninhomogeneity in the deposition-evaporation ratio by simulations, entropy-based\narguments and a study of the new terms introduced in the free energy. The\nprimary effect is that needles tend to align along the local spatial gradient\nof the ratio. A uniform gradient thus induces a uniformly aligned state, as\ndoes a gradient which varies randomly in magnitude and sign, but acts only in\none direction. Random variations of deposition-evaporation rates in both\ndirections induce frustration, resulting in a state with glassy\ncharacteristics."
    },
    {
        "anchor": "Maxwell plates and phonon fractionalization: In the past a few years, topologically protected mechanical phenomena have\nbeen extensively studied in discrete lattices and networks, leading to a rich\nset of discoveries such as topological boundary/interface floppy modes and\nstates of self stress, as well as one-way edge acoustic waves. In contrast,\ntopological states in continuum elasticity without repeating unit cells remain\nlargely unexplored, but offer wonderful opportunities for both new theories and\nbroad applications in technologies, due to their great convenience of\nfabrication. In this paper we examine continuous elastic media on the verge of\nmechanical instability, extend Maxwell-Calladine index theorem to continua in\nthe nonlinear regime, classify elastic media based on whether stress can be\nfully released, and identify two types of elastic media with topological\nstates. The first type, which we name ``Maxwell plates'', are in strong analogy\nwith Maxwell lattices, and exhibit a sub-extensive number of holographic floppy\nmodes. The second type, which arise in thin plates with a small bending\nstiffness and a negative Gaussian curvature, exhibit fractional excitations and\ntopological degeneracy, in strong analogy to $Z_2$ spin liquids and dimerized\nspin chains.",
        "positive": "What drives amyloid molecules to assemble into oligomers and fibrils?: We develop a general theory for three states of equilibrium of amyloid\npeptides: the monomer, oligomer, and fibril. We assume that the oligomeric\nstate is a disordered micelle-like collection of a few peptide chains held\ntogether loosely by hydrophobic interactions into a spherical hydrophobic core.\nWe assume that fibrillar amyloid chains are aligned and further stabilized by\n`steric zipper' interactions -- hydrogen bonding and steric packing, in\naddition to specific hydrophobic sidechain contacts. The model makes a broad\nset of predictions, consistent with experiments: (i) Similar to surfactant\nmicellization, amyloid oligomerization should increase with bulk peptide\nconcentration. (ii) The onset of fibrillization limits the concentration of\noligomers in the solution. (iii) The average fibril length \\emph{vs.} monomer\nconcentration agrees with data on $\\alpha$-synuclein, (iv) Full fibril length\ndistributions follow those of $\\alpha$-synuclein, (v) Denaturants should `melt\nout' fibrils, and (vi) Added salt should stabilize fibrils by reducing\nrepulsions between amyloid peptide chains. Interestingly, small changes in\nsolvent conditions can: (a) tip the equilibrium balance between oligomer and\nfibril, and (b) cause large changes in rates, through effects on the\ntransition-state barrier. This model may provide useful insights into the\nphysical processes underlying amyloid diseases."
    },
    {
        "anchor": "A hybrid method coupling fluctuating hydrodynamics and molecular\n  dynamics for the simulation of macromolecules: We present a hybrid computational method for simulating the dynamics of\nmacromolecules in solution which couples a mesoscale solver for the fluctuating\nhydrodynamics (FH) equations with molecular dynamics to describe the\nmacromolecule. The two models interact through a dissipative Stokesian term\nfirst introduced by Ahlrichs and D\\\"unweg [J. Chem. Phys. {\\bf 111}, 8225\n(1999)]. We show that our method correctly captures the static and dynamical\nproperties of polymer chains as predicted by the Zimm model. In particular, we\nshow that the static conformations are best described when the ratio\n$\\frac{\\sigma}{b}=0.6$, where $\\sigma$ is the Lennard-Jones length parameter\nand $b$ is the monomer bond length. We also find that the decay of the Rouse\nmodes' autocorrelation function is better described with an analytical\ncorrection suggested by Ahlrichs and D\\\"unweg. Our FH solver permits us to\ntreat the fluid equation of state and transport parameters as direct simulation\nparameters. The expected independence of the chain dynamics on various choices\nof fluid equation of state and bulk viscosity is recovered, while excellent\nagreement is found for the temperature and shear viscosity dependence of centre\nof mass diffusion between simulation results and predictions of the Zimm model.\nWe find that Zimm model approximations start to fail when the Schmidt number\n$Sc \\lessapprox 30$. Finally, we investigate the importance of fluid\nfluctuations and show that using the preaveraged approximation for the\nhydrodynamic tensor leads to around 3% error in the diffusion coefficient for a\npolymer chain when the fluid discretization size is greater than $50\\AA$.",
        "positive": "Architectures of Soft Robotic Locomotion Enabled by Simple Mechanical\n  Principles: In nature, a variety of limbless locomotion patterns flourish from the small\nor basic life form (Escherichia coli, the amoeba, etc.) to the large or\nintelligent creatures (e.g., slugs, starfishes, earthworms, octopuses,\njellyfishes, and snakes). Many bioinspired soft robots based on locomotion have\nbeen developed in the past decades. In this work, based on the kinematics and\ndynamics of two representative locomotion modes (i.e., worm-like crawling and\nsnake-like slithering), we propose a broad set of innovative designs for soft\nmobile robots through simple mechanical principles. Inspired by and go beyond\nexisting biological systems, these designs include 1-D (dimensional), 2-D, and\n3-D robotic locomotion patterns enabled by simple actuation of continuous\nbeams. We report herein over 20 locomotion modes achieving various locomotion\nfunctions, including crawling, rising, running, creeping, squirming,\nslithering, swimming, jumping, turning, turning over, helix rolling, wheeling,\netc. Some of them are able to reach high speed, high efficiency, and overcome\nobstacles. All these locomotion strategies and functions can be integrated into\na simple beam model. The proposed simple and robust models are adaptive for\nsevere and complex environments. These elegant designs for diverse robotic\nlocomotion patterns are expected to underpin future deployments of soft robots\nand to inspire series of advanced designs."
    },
    {
        "anchor": "Laser-induced instabilities in liquid crystal cells with a\n  photosensitive substrate: Liquid crystal layers sandwiched between a reference plate and a\nphotosensitive substrate were investigated. We focused on the reverse geometry,\nwhere the cell was illuminated by a laser beam from the reference side. In\nplanar cells instabilities occurred, static and dynamic ones, depending on the\nangle between the laser polarization and the director orientation on the\nreference plate. In cells where the molecules were aligned along the normal of\nthe reference plate, dynamic pattern was observed at all angles of\npolarization. A simple model based on a photo-induced surface torque gives\naccount of the findings. Light scattering studies revealed some basic\nproperties of the instabilities.",
        "positive": "Conformational Studies of bottle-brush polymers absorbed on a flat solid\n  surface: The adsorption of a bottle-brush polymer end-grafted with one chain end of\nits backbone to a flat substrate surface is studied by Monte Carlo simulation\nof a coarse-grained model, that previously has been characterized in the bulk,\nassuming a dilute solution under good solvent conditions. Applying the bond\nfluctuation model on the simple cubic lattice, we vary the backbone chain\nlength $N_b$ from $N_b=67$ to $N_b = 259$ effective monomeric units, the side\nchain length $N$ from N=6 to N=48, and the grafting density $\\sigma=1$, i.e.,\nparameters that correspond well to the experimentally accessible range. When\nthe adsorption energy strength $\\epsilon$ is varied, we find that the\nadsorption transition (which becomes well-defined in the limit $N_b \\rightarrow\n\\infty$, for arbitrary finite $N$) roughly occurs at the same value\n$\\epsilon_c$ as for ordinary linear chains (N=0), at least within our\nstatistical errors. Mean square end-to-end distances and gyration radii of the\nside chains are obtained, as well as the monomer density profile in the\ndirection perpendicular to the adsorbing surface. We show that for longer side\nchains the adsorption of bottle-brushes is a two step process, the decrease of\nthe perpendicular linear dimension of side chains with adsorption energy\nstrength can even be non-monotonic. Also the behavior of the static structure\nfactor $S(q)$ is analyzed, evidence for a quasi-two-dimensional scaling is\npresented, and consequences for the interpretation of experiments are\ndiscussed."
    },
    {
        "anchor": "Collective rearrangement at the onset of flow of a polycrystalline\n  hexagonal columnar phase: Creep experiments on polycrystalline surfactant hexagonal columnar phases\nshow a power law regime, followed by a drastic fluidization before reaching a\nfinal stationary flow. The scaling of the fluidization time with the shear\nmodulus of the sample and stress applied suggests that the onset of flow\ninvolves a bulk reorganization of the material. This is confirmed by X-ray\nscattering under stress coupled to \\textit{in situ} rheology experiments, which\nshow a collective reorientation of all crystallites at the onset of flow. The\nanalogy with the fracture of heterogeneous materials is discussed.",
        "positive": "Mode excitation Monte Carlo simulations of mesoscopically large\n  membranes: Solvent-free coarse grained models represent one of the most promising\napproaches for molecular simulations of mesoscopically large membranes. In\nthese models, the size of the simulated membrane is limited by the slow\nrelaxation time of longest bending mode. Here, we present a Monte Carlo\nalgorithm with update moves in which all the lipids are displaced\nsimultaneously. These collective moves result in fast excitation and relaxation\nof the long wavelength thermal fluctuations. We apply the method to simulations\nof a bilayer membrane of linear size $\\sim 50 {\\rm nm}$ and show reduction of\nthe relaxation time by two orders of magnitudes when compared to conventional\nMonte Carlo."
    },
    {
        "anchor": "Grain size effect on the compression and relaxation of a granular\n  column: solid particles vs dust agglomerates: We studied experimentally the effect of grain size and maximum load on the\ncompaction and subsequent relaxation of a granular column when it is subjected\nto vertical uniaxial compression. The experiments were performed using two\ndifferent types of grains: 1) solid glass beads, and 2) porous beads that\nconsist of agglomerates of glass powder. We found that the compression force\nincreases non-linearly with time, with sudden drops for the case of glass beads\nand periodic undulations for dust particles. Whereas the grain size effect is\nsmall in the average force load, the fluctuations become larger as the grain\nsize increases. On the other hand, the relaxation process is well described by\nthe Maxwell model with three different relaxation time scales.",
        "positive": "Anomalous fluctuations of two-dimensional Bose-Einstein condensates: We investigate the particle-number fluctuations due to the collective\nexcitations created in a two-dimensional (2D) and a quasi-2D Bose-Einstein\ncondensates (BECs) at low temperature. We find that the fluctuations display an\nanomalous behavior, i. e. for the 2D BEC they are proportional to $N^2$, where\n$N$ is the total number of particles. For the quasi-2D BEC, the particle-number\nfluctuations are proportional not only to $N^2$ but also to the square root of\nthe trapping frequency in the strongly-confined direction."
    },
    {
        "anchor": "Supramolecular structures in monohydroxy alcohols: Insights from\n  shear-mechanical studies of a systematic series of octanol structural isomers: A recent study [Gainaru et al. PRL., 112, 098301 (2014)] of two supercooled\nmonohydroxy alcohols close to the glass-transition temperature showed that the\nDebye peak, thus far mainly observed in the electrical response, also has a\nmechanical signature. In this work, we apply broadband shear-mechanical\nspectroscopy to a systematic series of octanol structural isomers,\nx-methyl-3-heptanol (with x ranging from 2 to 6). We find that the\ncharacteristics of the mechanical signature overall follow the systematic\nbehavior observed in dielectric spectroscopy. However, the influence from the\nmolecular structure is strikingly small in mechanics (compared to roughly a\nfactor 100 increase in dielectric strength) and one isomer clearly does not\nconform to the general ordering. Finally, the mechanical data surprisingly\nindicate that the size of the supramolecular structures responsible for the\nDebye process is nearly unchanged in the series.",
        "positive": "Eigenvalue analysis of stress-strain curve of two-dimensional amorphous\n  solids of dispersed frictional grains with finite shear strain: The stress-strain curve of two-dimensional frictional dispersed grains\ninteracting with a harmonic potential without considering the dynamical slip\nunder a finite strain is determined by using eigenvalue analysis of the Hessian\nmatrix. After the configuration of grains is obtained, the stress-strain curve\nbased on the eigenvalue analysis is in almost perfect agreement with that\nobtained by the simulation, even if there are plastic deformations caused by\nstress avalanches. Unlike the naive expectation, the eigenvalues in our model\ndo not indicate any precursors to the stress-drop events."
    },
    {
        "anchor": "Phase diagram of two-species Bose-Einstein condensates in an optical\n  lattice: The exact macroscopic wave functions of two-species Bose-Einstein condensates\nin an optical lattice beyond the tight-binding approximation are studied by\nsolving the coupled nonlinear Schrodinger equations. The phase diagram for\nsuperfluid and insulator phases of the condensates is determined analytically\naccording to the macroscopic wave functions of the condensates, which are seen\nto be traveling matter waves.",
        "positive": "Chain Length Dispersity Effects on Mobility of Entangled Polymers: While nearly all theoretical and computational studies of entangled polymer\nmelts have focused on uniform samples, polymer synthesis routes always result\nin some dispersity, albeit narrow, of distribution of molecular weights\n(D_M=M_w/M_n ~ 1.02-1.04). Here the effects of dispersity on chain mobility are\nstudied for entangled, disperse melts using a coarse-grained model for\npolyethylene. Polymer melts with chain lengths set to follow a Schulz-Zimm\ndistribution for the same average M_w = 36 kg/mol with D_M = 1.0 to 1.16, were\nstudied for times of $600-800$ $\\mu$s using molecular dynamics simulations.\nThis time frame is longer than the time required to reach the diffusive regime.\nWe find that dispersity in this range does not affect the entanglement time or\ntube diameter. However, while there is negligible difference in the average\nmobility of chains for the uniform distribution D_M=1.0 and D_M = 1.02, the\nshortest chains move significantly faster than the longest ones offering a\nconstraint release pathway for the melts for larger D_M."
    },
    {
        "anchor": "Super-lattice, rhombus, square, and hexagonal standing waves in\n  magnetically driven ferrofluid surface: Standing wave patterns that arise on the surface of ferrofluids by (single\nfrequency) parametric forcing with an ac magnetic field are investigated\nexperimentally. Depending on the frequency and amplitude of the forcing, the\nsystem exhibits various patterns including a superlattice and subharmonic\nrhombuses as well as conventional harmonic hexagons and subharmonic squares.\nThe superlattice arises in a bicritical situation where harmonic and\nsubharmonic modes collide. The rhombic pattern arises due to the non-monotonic\ndispersion relation of a ferrofluid.",
        "positive": "Local stress and pressure in an inhomogeneous system of spherical active\n  Brownian particles: The stress of a fluid on a confining wall is given by the mechanical wall\nforces, independent of the nature of the fluid being passive or active. At\nthermal equilibrium, an equation of state exists and stress is likewise\nobtained from intrinsic bulk properties; even more, stress can be calculated\nlocally. Comparable local descriptions for active systems require a particular\nconsideration of active forces. Here, we derive expressions for the stress\nexerted on a local volume of a systems of spherical active Brownian particles\n(ABPs). Using the virial theorem, we obtain two identical stress expressions, a\nstress due to momentum flux across a hypothetical plane, and a bulk stress\ninside of the local volume. In the first case, we obtain an active contribution\nto momentum transport in analogy to momentum transport in an underdamped\npassive system, and we introduce an active momentum. In the second case, a\ngenerally valid expression for the swim stress is derived. By simulations, we\ndemonstrate that the local bulk stress is identical to the wall stress of a\nconfined system for both, non-interacting ABPs as well as ABPs with\nexcluded-volume interactions. This underlines the existence of an equation of\nstate for a system of spherical ABPs. Most importantly, our calculations\ndemonstrated that active stress is not a wall (boundary) effect, but is caused\nby momentum transport. We demonstrate that the derived stress expression\npermits the calculation of the local stress in inhomogeneous systems of ABPs."
    },
    {
        "anchor": "The delamination of a growing elastic sheet with adhesion: We study the onset of delamination blisters in a growing elastic sheet\nadhered to a flat stiff substrate. When the ends of the sheet are kept fixed,\nits growth arouses residual stresses that lead to delamination. This\ninstability can be viewed as a discontinuous buckling between the complete\nadhered solution and the buckled solution. We provide an analytic expression\nfor the critical deformation at which the instability occurs. We show that the\ncritical threshold scales with a single dimensionless parameter that comprises\ninformation from the geometry of the sheet, the mechanical parameters of\nmaterial and the adhesive features of the substrate.",
        "positive": "Three-dimensional ultrasonic colloidal crystals: Colloidal assembly represents a powerful method for the fabrication of\nfunctional materials. In this article, we describe how acoustic radiation\nforces can guide the assembly of colloidal particles into structures that serve\nas microscopic elements in novel acoustic metadevices or act as phononic\ncrystals. Using a simple three-dimensional orthogonal system, we show that a\ndiversity of colloidal structures with orthorhombic symmetry can be assembled\nwith megahertz-frequency (MHz) standing pressure waves. These structures allow\nrapid tuning of acoustic properties and provide a new platform for dynamic\nmetamaterial applications."
    },
    {
        "anchor": "Tuning Nonequilibrium Phase Transitions with Inertia: In striking contrast to equilibrium systems, inertia can profoundly alter the\nstructure of active systems. Here, we demonstrate that driven systems can\nexhibit effective equilibrium-like states with increasing particle inertia,\ndespite rigorously violating the fluctuation-dissipation theorem. Increasing\ninertia progressively eliminates motility-induced phase separation and restores\nequilibrium crystallization for active Brownian spheres. This effect appears to\nbe general for a wide class of active systems, including those driven by\ndeterministic time-dependent external fields, whose nonequilibrium patterns\nultimately disappear with increasing inertia. The path to this effective\nequilibrium limit can be complex, with finite inertia sometimes acting to\naccentuate nonequilibrium transitions. The restoration of near equilibrium\nstatistics can be understood through the conversion of active momentum sources\nto passive-like stresses. Unlike truly equilibrium systems, the effective\ntemperature is now density dependent, the only remnant of the nonequilibrium\ndynamics. This density-dependent temperature can in principle introduce\ndepartures from equilibrium expectations, particularly in response to strong\ngradients. Our results provide additional insight into the effective\ntemperature ansatz while revealing a mechanism to tune nonequilibrium phase\ntransitions.",
        "positive": "Phase diagrams and ordering in charged membranes: Binary mixtures of\n  charged and neutral lipids: We propose a model describing the phase behavior of two-component membranes\nconsisting of binary mixtures of electrically charged and neutral lipids. We\ntake into account the structural phase transition (main-transition) of the\nhydrocarbon chains, and investigate the interplay between this phase transition\nand the lateral phase separation. The presence of charged lipids significantly\naffects the phase behavior of the multi-component membrane. Due to the\nconservation of lipid molecular volume, the main-transition temperature of\ncharged lipids is lower than that of neutral ones. Furthermore, as compared\nwith binary mixtures of neutral lipids, the membrane phase separation in binary\nmixtures of charged lipids is suppressed, in accord with recent experiments. We\ndistinguish between two types of charged membranes: mixtures of charged\nsaturated lipid/neutral unsaturated lipid and a second case of mixtures of\nneutral saturated lipid/charged unsaturated lipid. The corresponding phase\nbehavior is calculated and shown to be very different. Finally, we discuss the\neffect of added salt on the phase separation and the temperature dependence of\nthe lipid molecular area."
    },
    {
        "anchor": "Microphase transitions of block copolymer/homopolymer under shear flow: Cell dynamics simulation is used to investigate the phase behavior of block\ncopolymer/homopolymer mixture subjected to a steady shear flow. Phase\ntransitions occur from transverse to parallel and then to perpendicular\nlamellar structure with an increase of shear rate and this is the result of\ninteraction between the shear flow and the concentration fluctuation.\nRheological properties, such as normal stress differences and shear viscosity,\nare all closely related with the direction of the lamellae. Furthermore, we\nspecifically explore the phase behavior and the order parameter under weak and\nstrong shear of two different initial states, and realize the importance of the\nthermal history. It is necessary to apply the shear field at the appropriate\ntime if we want to get what we want. These results provide an easy method to\ncreate ordered, defect-free materials in experiment and engineering technology\nthrough imposing shear flow.",
        "positive": "Analytical modeling of micelle growth. 3. Electrostatic free energy of\n  ionic wormlike micelles -- effects of activity coefficients and spatially\n  confined electric double layers: Hypotheses: To correctly predict the aggregation number and size of wormlike\nmicelles from ionic surfactants, the molecular-thermodynamic theory has to\ncalculate the free energy per molecule in the micelle with accuracy better than\n0.01 kT, which is a serious challenge. The problem could be solved if the\neffects of mutual confinement of micelle counterion atmospheres, as well as the\neffects of counterion binding, surface curvature and ionic interactions in the\nelectric double layer (EDL), are accurately described. Theory: The electric\nfield is calculated using an appropriate cell model, which takes into account\nthe aforementioned effects. Expressions for the activity coefficients have been\nused, which vary across the EDL and describe the electrostatic, hard sphere,\nand specific interactions between the ions. New approach for fast numerical\ncalculation of the electrostatic free energy is developed. Findings: The\nnumerical results demonstrate the variation of quantities characterizing the\nEDL of cylindrical and spherical micelles with the rise of electrolyte\nconcentration. The effect of activity coefficients leads to higher values of\nthe free energy per surfactant molecule in the micelle as compared with the\ncase of neglected ionic interactions. The results are essential for the correct\nprediction of the size of wormlike micelles from ionic surfactants. This study\ncan be extended to mixed micelles of ionic and nonionic surfactants for\ninterpretation of the observed synergistic effects."
    },
    {
        "anchor": "Emergence of Quasi-equilibrium State and Energy Distribution for the\n  Beads-spring Molecule Interacting with a Solvent: We study the energy distribution during the emergence of a quasi-equilibrium\n(QE) state in the course of relaxation to equipartition in slow-fast\nHamiltonian systems. A bead-spring model where beads (masses) are connected by\nsprings is considered, and it is used as a model of polymers. The QE lasts for\na long time because the energy exchange between the high-frequency vibrational\nand other motions is prevented when springs in the molecule become stiff. We\nnumerically calculated the time-averaged kinetic energy and found that the\nkinetic energy of the solvent particles was always higher than that of the bead\nin a molecule. This is explained by adapting the equipartition theorem in QE,\nand it agrees well with the numerical results. The energy difference can help\ndetermine how far the system is from achieving equilibrium, and it can be used\nas an indicator of the number of frozen or inactive degrees exist in the\nmolecule.",
        "positive": "Dancing disclinations in confined active nematics: The spontaneous emergence of collective flows is a generic property of active\nfluids and often leads to chaotic flow patterns characterised by swirls, jets,\nand topological disclinations in their orientation field. However, the ability\nto achieve structured flows and ordered disclinations is of particular\nimportance in the design and control of active systems. By confining an active\nnematic fluid within a channel, we find a regular motion of disclinations, in\nconjunction with a well defined and dynamic vortex lattice. As pairs of moving\ndisclinations travel through the channel, they continually exchange partners\nproducing a dynamic ordered state, reminiscent of Ceilidh dancing. We\nanticipate that this biomimetic ability to self-assemble organised topological\ndisclinations and dynamically structured flow fields in engineered geometries\nwill pave the road towards establishing new active topological microfluidic\ndevices."
    },
    {
        "anchor": "Equilibration between Translational and Rotational Modes in Molecular\n  Dynamics Simulations of Rigid Water Requires a Smaller Integration Time-Step\n  Than Often Used: In simulations of aqueous systems it is common to freeze the bond vibration\nand angle bending modes in water to allow for a longer time-step $\\delta t$ for\nintegrating the equations of motion. Thus $\\delta t = 2$ fs is often used in\nsimulating rigid models of water. We simulate the SPC/E model of water using\n$\\delta t$ from 0.5 fs to 3.0 fs. We find that for all but $\\delta = 0.5$ fs,\nequipartition between translational and rotational modes is violated: the\nrotational modes are at a lower temperature than the translation modes. The\nautocorrelation of the velocities corresponding to the respective modes shows\nthat the rotational relaxation occurs at a time-scale comparable to vibrational\nperiods, invalidating the original assumption for freezing vibrations. $\\delta\nt$ also influences thermodynamic properties: the mean system potential energies\nare not converged until $\\delta t = 0.5$ fs, and the excess entropy of\nhydration of a soft, repulsive cavity is also sensitive to $\\delta t$.",
        "positive": "Impulsive stimulated scatttering signal in supercooled liquids with\n  Debye or Havriliak-Negami relaxation of the specific heat capacity and\n  thermal expansion coefficient: A generalized physical model is introduced to describe the impulsive\nstimulated scattering (ISS) response of relaxing systems to photothermal\nexcitation in a periodical grating geometry. The proposed approach starts from\nDebye and Havriliak-Negami expressions for both the frequency-dependent heat\ncapacity, C({\\omega}), and thermal expansion coefficient, {\\gamma}({\\omega}).\nSimulations are carried out on glycerol to test and compare the developed\nmodels with the existing semi-empirical model [1]. Debye behavior of the\nspecific heat capacity is shown to be compatible with a two-temperature\nscenario, in which, in addition to the classical, experimentally observable\ntemperature that characterizes the distribution of the system over vibrational\nenergy states, a second temperature characterizes the state of the\nconfigurational energy landscape. The models here developed have been applied\nfor the interpretation of the experimental ISS signals of supercooled glycerol,\nillustrating simultaneous and separate assessment of C({\\omega}) and\n{\\gamma}({\\omega}) up to sub-100 MHz from thermoelastic transients."
    },
    {
        "anchor": "Enhanced scattering induced by electrostatic correlations in\n  concentrated solutions of salt-free dipolar and ionic polymers: We present a generalized theory for studying static monomer density-density\ncorrelation function (structure factor) in concentrated solutions and melts of\ndipolar as well as ionic polymers. The theory captures effects of electrostatic\nfluctuations on the structure factor and provides insights into the origin of\nexperimentally observed enhanced scattering at ultralow wavevectors in\nsalt-free ionic polymers. It is shown that the enhanced scattering can\noriginate from a coupling between fluctuations of electric polarization and\nmonomer density. Local and non-local effects of the polarization resulting from\nfinite sized permanent dipoles and ion-pairs in dipolar and charge regulating\nionic polymers, respectively, are considered. Theoretical calculations reveal\nthat, similar to the salt-free ionic polymers, the structure factor for dipolar\npolymers can also exhibit a peak at a finite wavevector and enhanced scattering\nat ultralow wavevectors. Although consideration of dipolar interactions leads\nto attractive interactions between monomers, the enhanced scattering at\nultralow wavevectors is predicted solely on the basis of the electrostatics of\nweakly inhomoge- neous dipolar and ionic polymers without considering the\neffects of any aggregates or phase separation. Thus, we conclude that neither\naggregation nor phase separation is necessary for observing the enhanced\nscattering at ultralow wave-vectors in salt-free dipolar and ionic polymers.\nFor charge regulating ionic polymers, it is shown that electrostatic\ninteractions between charged monomers get screened with a screening length,\nwhich depends not only on the concentration of free counterions and coions but\nalso on the concentration of adsorbed ions on the polymer chains. Qualitative\ncomparisons with the experimental scattering curves for ionic and dipolar\npolymer melts are presented using the theory developed in this work.",
        "positive": "Mean field analysis of Williams-Bjerknes type growth: We investigate a class of stochastic growth models involving competition\nbetween two phases in which one of the phases has a competitive advantage. The\nequilibrium populations of the competing phases are calculated using a mean\nfield analysis. Regression probabilities for the extinction of the advantaged\nphase are calculated in a leading order approximation. The results of the\ncalculations are in good agreement with simulations carried out on a square\nlattice with periodic boundaries. The class of models are variants of the\nWilliams- Bjerknes model for the growth of tumours in the basal layer of an\nepithelium. In the limit in which only one of the phases is unstable the class\nof models reduces to the well known variants of the Eden model."
    },
    {
        "anchor": "The effect of scatter of polymer chain length on strength: A polymer network fractures by breaking covalent bonds, but the\nexperimentally measured strength of the polymer network is orders of magnitude\nlower than the strength of covalent bonds. We investigate the effect of\nstatistical variation of the number of links in polymer chains on strength\nusing a parallel chain model. Each polymer chain is represented by a\nfreely-jointed chain, with a characteristic J-shaped force-extension curve. The\nchain carries entropic forces for most of the extension and carries covalent\nforces only for a narrow range of extension. The entropic forces are orders of\nmagnitude lower than the covalent forces. Chains with a statistical\ndistribution of the number of links per chain are pulled between two rigid\nparallel plates. Chains with fewer links attain covalent forces and rupture at\nsmaller extensions, while chains with more links still carry entropic forces.\nWe compute the applied force on the rigid plates as a function of extension and\ndefine the strength of the parallel chain model by the maximum force divided by\nthe total number of chains. With the J-shaped force-extension curve of each\nchain, even a small scatter in the number of links per chain greatly reduces\nthe strength of the parallel chain model. We further show that the strength of\nthe parallel chain model relates to the scatter in the number of links per\nchain according to a power law.",
        "positive": "Gelation in Multiple Link Systems: Within the framework of the random distribution assumption of cyclic bonds,\nthe theory of gelation is extended to mixing systems of the R-Ag + R-Bf-g\nmodel, which is expected to have wider application such as micell formations in\nbiological systems. We derive the gel point expression of this biologically\ninteresting new system."
    },
    {
        "anchor": "Long-term stable poly(ionic liquid)/MWCNTs inks enable enhanced surface\n  modification for electrooxidative detection and quantification of dsDNA: This work demonstrates the use of imidazolium-based poly(ionic liquid)s\n(PILs) as efficient dispersants of multi-walled carbon nanotubes (MWCNTs). With\nthese polymeric dispersants, highly stable fine dispersions of MWCNTs (inks)\ncan be easily prepared in aqueous media and applied for rather simple but\nefficient surface modification of screen-printed electrodes (SPEs). Such a\nmodification of SPEs remarkably increases the electroactive surface area and\naccelerates the electron transfer rate due to synergistic combination of\nspecific features of MWCNTs such as strong adsorptive property and high\nspecific surface with the advantages of PILs like ion conductivity and\ndispersability. We further show that the PIL/MWCNT-modified SPEs can be\nbeneficially utilized for direct electrochemical analysis of double stranded\nDNA (dsDNA). Specifically, it is exemplified by the direct electrooxidation of\nguanine and adenine bases in salmon testes dsDNA chosen as a model system. The\nlinear ranges for the determination of dsDNA correspond to 5-500 microg per mL\nfor the oxidative peak of guanine and 0.5-50 microg per mL for the oxidative\npeak of adenine. This makes direct electrochemical dsDNA detection with the use\nof the easy-preparable PIL/MWCNT-modified SPEs strongly competing to currently\napplied spectral and fluorescent techniques. Furthermore, we show that the\ndeveloped constructs are capable of sensing a single point mutation in the\n12-bases single-stranded DNA fragments. Such detection is of high clinical\nsignificance in choosing an adequate anticancer treatment, where the\nelectrochemical identification of the point mutation could offer time and cost\nbenefits.",
        "positive": "Collective dynamics in a binary mixture of hydrodynamically coupled\n  micro-rotors: We study, numerically, the collective dynamics of self-rotating nonaligning\nparticles by considering a monolayer of spheres driven by constant clockwise or\ncounterclockwise torques. We show that hydrodynamic interactions alter the\nemergence of large-scale dynamical patterns compared to those observed in dry\nsystems. In dilute suspensions, the flow stirred by the rotors induces\nclustering of opposite-spin rotors, while at higher densities same-spin rotors\nphase separate. Above a critical rotor density, dynamic hexagonal crystals\nform. Our findings underscore the importance of inclusion of the many-body,\nlong-range hydrodynamic interactions in predicting the phase behavior of active\nparticles."
    },
    {
        "anchor": "Emergent colloidal edge currents generated via exchange dynamics in a\n  broken dimer state: Controlling the flow of matter down to micrometer-scale confinement is of\ncentral importance in materials and environmental sciences, with direct\napplications in nano-microfluidics, drug delivery and biothechnology. Currents\nof microparticles are usually generated with external field gradients of\ndifferent nature [e.g., electric, magnetic, optical, thermal or chemical ones]\nwhich are difficult to control over spatially extended regions and samples.\nHere we demonstrate a general strategy to assemble and transport polarizable\nmicroparticles in fluid media through combination of confinement and magnetic\ndipolar interactions. We use a homogeneous magnetic modulation to assemble\ndispersed particles into rotating dimeric state and frustrated binary lattices,\nand generate collective edge currents which arise from a novel,\nfield-synchronized particle exchange process. These dynamic states are similar\nto cyclotron and skipping orbits in electronic and molecular systems, thus\npaving the way toward understanding and engineering similar processes at\ndifferent length scales across condensed matter.",
        "positive": "Translationally invariant colloidal crystal templates: We show that dynamic, feed-back controlled optical traps, whose positions\ndepend on the instantaneous local configuration of particles in a\npre-determined way, can stabilise colloidal particles in finite lattices of\n${\\it any}$ given symmetry. Unlike in a static template, the crystal so formed\nis translationally invariant and retains all possible zero energy modes. We\ndemonstrate this ${\\it in-silico}$ by stabilising the unstable two-dimensional\n${\\it square}$ lattice in a model soft solid with isotropic interactions."
    },
    {
        "anchor": "Many-body interactions and melting of colloidal crystals: We study the melting behavior of charged colloidal crystals, using a\nsimulation technique that combines a continuous mean-field Poisson-Boltzmann\ndescription for the microscopic electrolyte ions with a Brownian-dynamics\nsimulation for the mesoscopic colloids. This technique ensures that many-body\ninteractions between the colloids are fully taken into account, and thus allows\nus to investigate how many-body interactions affect the solid-liquid phase\nbehavior of charged colloids. Using the Lindemann criterion, we determine the\nmelting line in a phase-diagram spanned by the colloidal charge and the salt\nconcentration. We compare our results to predictions based on the established\ndescription of colloidal suspensions in terms of pairwise additive Yukawa\npotentials, and find good agreement at high-salt, but not at low-salt\nconcentration. Analyzing the effective pair-interaction between two colloids in\na crystalline environment, we demonstrate that the difference in the melting\nbehavior observed at low salt is due to many-body interactions.",
        "positive": "Complex motion of steerable vesicular robots filled with active\n  colloidal rods: While the collective motion of active particles has been studied extensively,\neffective strategies to navigate particle swarms without external guidance\nremain elusive. We introduce a method to control the trajectories of\ntwo-dimensional swarms of active rod-like particles by confining the particles\nto rigid bounding membranes (vesicles) with non-uniform curvature. We show that\nthe propelling agents spontaneously form clusters at the membrane wall and\ncollectively propel the vesicle, turning it into an active superstructure. To\nfurther guide the motion of the superstructure, we add discontinuous features\nto the rigid membrane boundary in the form of a kinked tip, which acts as a\nsteering component to direct the motion of the vesicle. We report that the\nsystem's geometrical and material properties, such as the aspect ratio and\nPeclet number of the active rods as well as the kink angle and flexibility of\nthe membrane, determine the stacking of active particles close to the kinked\nconfinement and induce a diverse set of dynamical behaviors of the\nsuperstructure, including linear and circular motion both in the direction of,\nand opposite to, the kink. From a systematic study of these various behaviors,\nwe design vesicles with switchable and reversible locomotions by tuning the\nconfinement parameters. The observed phenomena suggest a promising mechanism\nfor particle transportation and could be used as a basic element to navigate\nactive matter through complex and tortuous environments."
    },
    {
        "anchor": "On the shift in membrane miscibility transition temperature upon\n  addition of short-chain alcohols: I consider the effect of a small concentration of a molecule, such as a\nshort-chain alcohol, on the miscibility transition temperature of a giant\nplasma membrane vesicle. For concentrations sufficiently small such that the\nsystem can be treated as a weak solution, the change in transition temperature\nis known to depend upon the extent of the molecule's partition into the\ncoexisting liquid-disordered and liquid-ordered phases. Preferential\npartitioning into the former decreases the miscibility temperature, while\npreferential partitioning into the latter causes an increase. The analysis,\ncombined with calculated values of the partition coefficient of saturated\nchains, illuminates the results of recent experiments on the change in\nmiscibility transition temperatures with changing alcohol chain length, and\nmakes several testable predictions.",
        "positive": "Single-file and normal diffusion of magnetic colloids in modulated\n  channels: Diffusive properties of interacting magnetic dipoles confined in a parabolic\nnarrow channel and in the presence of a periodic modulated (corrugated)\npotential along the unconfined direction are studied using Brownian dynamics\nsimulations. We compare our simulation results with the analytical result for\nthe effective diffusion coefficient of a single-particle by Festa and d'Agliano\n[Physica A \\textbf{90}, 229 (1978)] and show the importance of inter-particle\ninteraction on the diffusion process. We present results for the diffusion of\nmagnetic dipoles as a function of linear density, strength of the periodic\nmodulation and commensurability factor."
    },
    {
        "anchor": "Insights on drying and precipitation dynamics of respiratory droplets in\n  the perspective of Covid-19: We isolate a nano-colloidal droplet of surrogate mucosalivary fluid to gain\nfundamental insights into the infectivity of air borne nuclei during the\nCovid-19 pandemic. Evaporation experiments are performed with salt-water\nsolutions seeded with a viral load of inactive nanoparticles in an acoustic\nlevitator. We seek to emulate the drying, flow and precipitation dynamics of\nsuch air borne mucosalivary droplets. Observations with the surrogate fluid are\nvalidated by similar experiments with actual samples from a healthy subject. A\nunique feature emerges with regards to the final crystallite dimension; it is\nalways 20-30% of the initial droplet diameter for different sizes and ambient\nconditions. The preserved precipitates from levitated droplets show that 15% of\nthe total virion population remain dispersed on the outer surface of\nair-desiccated air borne nuclei. This fraction increases to ~90% if the\nrespiratory droplets (of larger initial size) settle on a surface and then\nevaporate in the sessile mode.",
        "positive": "Multi-particle-collision dynamics: Flow around a circular and a square\n  cylinder: A particle-based model for mesoscopic fluid dynamics is used to simulate\nsteady and unsteady flows around a circular and a square cylinder in a\ntwo-dimensional channel for a range of Reynolds number between 10 and 130.\nNumerical results for the recirculation length, the drag coefficient, and the\nStrouhal number are reported and compared with previous experimental\nmeasurements and computational fluid dynamics data. The good agreement\ndemonstrates the potential of this method for the investigation of complex\nflows."
    },
    {
        "anchor": "Landscape equivalent of the shoving model: It is shown that the shoving model expression for the average relaxation time\nof viscous liquids follows largely from a classical \"landscape\" estimation of\nbarrier heights from curvature at energy minima. The activation energy involves\nboth instantaneous bulk and shear moduli, but the bulk modulus contributes less\nthan 8% to the temperature dependence of the activation energy. This reflects\nthe fact that the physics of the two models are closely related.",
        "positive": "Energy Production Rates of Multicomponent Granular Gases of Rough\n  Particles. A Unified View of Hard-Disk and Hard-Sphere Systems: Granular gas mixtures modeled as systems of inelastic and rough particles,\neither hard disks on a plane or hard spheres, are considered. Both classes of\nsystems are embedded in a three-dimensional space ($d=3$) but, while in the\nhard-sphere case the translational and angular velocities are vectors with the\nsame dimensionality (and thus there are $d_{\\text{tr}}=3$ translational and\n$d_{\\text{rot}}=3$ rotational degrees of freedom), in the hard-disk case the\ntranslational velocity vectors are planar (i.e., $d_{\\text{tr}}=2$\ntranslational degrees of freedom) and the angular velocity vectors are\northogonal to the motion plane (i.e., $d_{\\text{rot}}=1$ rotational degree of\nfreedom). This complicates a unified presentation of both classes of systems,\nin contrast to what happens for smooth, spinless particles, where a treatment\nof $d$-dimensional spheres is possible. In this paper, a kinetic-theory\nderivation of the (collisional) energy production rates $\\xi_{ij}^{\\text{tr}}$\nand $\\xi_{ij}^{\\text{rot}}$ (where the indices $i$ and $j$ label different\ncomponents) in terms of the numbers of degrees of freedom $d_{\\text{tr}}$ and\n$d_{\\text{rot}}$ is presented. Known hard-sphere and hard-disk expressions are\nrecovered by particularizing to $(d_{\\text{tr}},d_{\\text{rot}})=(3,3)$ and\n$(d_{\\text{tr}},d_{\\text{rot}})=(2,1)$, respectively. Moreover, in the case of\nspinless particles with $d=d_{\\text{tr}}$, known energy production rates\n$\\xi_{ij}^{\\text{tr}}=\\xi_{ij}$ of smooth $d$-dimensional spheres are also\nrecovered."
    },
    {
        "anchor": "Structuring Stress for Active Materials Control: Active materials are capable of converting free energy into mechanical work\nto produce autonomous motion, and exhibit striking collective dynamics that\nbiology relies on for essential functions. Controlling those dynamics and\ntransport in synthetic systems has been particularly challenging. Here, we\nintroduce the concept of spatially structured activity as a means to control\nand manipulate transport in active nematic liquid crystals consisting of actin\nfilaments and light-sensitive myosin motors. Simulations and experiments are\nused to demonstrate that topological defects can be generated at will, and then\nconstrained to move along specified trajectories, by inducing local stresses in\nan otherwise passive material. These results provide a foundation for design of\nautonomous and reconfigurable microfluidic systems where transport is\ncontrolled by modulating activity with light.",
        "positive": "Physics of Solutions and Networks of Semiflexible Macromolecules and the\n  Control of Cell Function: Living cells are soft bodies of a characteristic form, but endowed with a\ncapacity for a steady turnover of their structures. Both of these material\nproperties, i.e. recovery of the shape after an external stress has been\nimposed and dynamic structural reorganization, are essential for many cellular\nphenomena. Examples are mechanical properties of tissue, cell motility, cell\ngrowth and division, and active intracellular transport. Numerous experiments\nin vivo and in vitro have shown that the structural element responsible for the\nextraordinary mechanical and dynamical properties of eukaryotic cells is the\ncytoskeleton, a three-dimensional assembly of protein fibers such as actin\nfilaments and microtubules. In addition to those biopolymers various proteins\nwith structural and regulatory functions have a major influence on the\nmechanical properties. At the relevant length-scales (a few microns at most)\nthe building blocks of these biomaterials are very different from conventional\npolymeric material. In contrast to flexible polymers the persistence length is\nof the same order of magnitude as their total contour length or even larger.\nThis implies that the physics of such a system is determined by a subtle\ninterplay between energetic and entropic contributions. We review our present\nunderstanding of the physics of biopolymers using concepts from macromolecular\nand statistical physics complemented by computer simulation. These systems open\nup a new field of soft condensed matter research, which to date is only poorly\nunderstood but has a great potential for interesting new physical phenomena."
    },
    {
        "anchor": "The interaction of hybrid nanoparticles inserted within surfactant\n  bilayers: We determine by small-angle x-ray scattering the structure factor of\nhydrophobic particles inserted within lamellar surfactant phases for various\nparticle concentrations. The data are then analyzed by numerically solving the\nOrnstein-Zernicke equation, taking into account both the intra- and interlayer\ninteractions. We find that particles within the same layer repel each other and\nthat the interaction potential (taken as independent of the concentration) has\na contact value of 2.2 k$_{\\text{B}}$T and a range of about 10 {\\AA}. If the\namplitude is allowed to decrease with increasing concentration, the contact\nvalue in the dilute limit is about 5 k$_{\\text{B}}$T for a similar range.",
        "positive": "The influence of complex thermal treatment on mechanical properties of\n  amorphous materials: We study the effect of periodic, spatially uniform temperature variation on\nmechanical properties and structural relaxation of amorphous alloys using\nmolecular dynamics simulations. The disordered material is modeled via a\nnon-additive binary mixture, which is annealed from the liquid to the glassy\nstate with various cooling rates and then either aged at constant temperature\nor subjected to thermal treatment. We found that in comparison to aged samples,\nthermal cycling with respect to a reference temperature of approximately half\nthe glass transition temperature leads to more relaxed states with lower levels\nof potential energy. The largest energy decrease was observed for rapidly\nquenched glasses cycled with the thermal amplitude slightly smaller than the\nreference temperature. Following the thermal treatment, the mechanical\nproperties were probed via uniaxial tensile strain at the reference temperature\nand constant pressure. The numerical results indicate an inverse correlation\nbetween the levels of potential energy and values of the elastic modulus and\nyield stress as a function of the thermal amplitude."
    },
    {
        "anchor": "Collective behavior of bulk nanobubbles produced by the alternating\n  polarity electrolysis: Nanobubbles in liquids are mysterious gaseous objects having exceptional\nstability. They promise a wide range of applications but their production is\nnot well controlled and localized. Alternating polarity electrolysis of water\nis a tool that can control production of bulk nanobubbles in space and time\nwithout generating larger bubbles. Using the schlieren technique a detailed\nthree-dimensional structure of a dense cloud of nanobubbles above the\nelectrodes is visualized. It is demonstrated that the thermal effects produce\ndifferent schlieren pattern and have different dynamics. A localized volume\nenriched with nanobubbles can be separated from the parent cloud and exists on\nits own. This volume demonstrates buoyancy from which the concentration of\nnanobubbles is estimated as 2x10^18 m^-3. This concentration is smaller than\nthat in the parent cloud. Dynamic light scattering shows that the average size\nof nanobubbles during the process is 60-80 nm. The bubbles are observed 15\nminutes after switching off the electrical pulses but their size is shifted to\nlarger values of about 250 nm. Thus, an efficient way to generate and control\nnanobubbles is proposed.",
        "positive": "Microrheology to probe non-local effects in dense granular flows: A granular material is observed to flow under the Coulomb yield criterion as\nsoon as this criterion is satisfied in a remote but contiguous region of space.\nWe investigate this non-local effect using discrete element simulations, in a\ngeometry similar, in spirit, to the experiment of Reddy et al. (Phys. Rev.\nLett., 106 (2011) 108301): a micro-rheometer is introduced to determine the\ninfluence of a distant shear band on the local rheological behaviour. The\nnumerical simulations recover the dominant features of this experiment: the\nlocal shear rate is proportional to that in the shear band and decreases\n(roughly) exponentially with the distance to the yield conditions. The\nnumerical results are in quantitative agreement with the predictions of the\nnon-local rheology proposed by (Phys. Rev. Lett., 111 (2013) 238301) and\nderived from a gradient expansion of the rheology $\\mu[I]$. The consequences of\nthese findings for the dynamical mechanisms controlling non-locality are\nfinally discussed."
    },
    {
        "anchor": "How a Blister Heals: We use experiments to study the dynamics of the healing of a blister, a\nlocalized bump in a thin elastic layer that is adhered to a soft substrate\neverywhere except at the bump. We create a blister by gently placing a glass\ncover slip on a PDMS substrate. The pressure jump across the elastic layer\ndrives fluid flow through micro-channels that form at the interface between the\nlayer and the substrate; these channels coalesce at discrete locations as the\nblister heals and eventually disappear at a lower critical radius. The spacing\nof the channel follows a simple scaling law that can be theoretically\njustified, and the kinetics of healing is rate limited by fluid flow, but with\na non-trivial dependence on the substrate thickness that likely arises due to\nchannelization. Our study is relevant to a variety of soft adhesion scenarios.",
        "positive": "Phase behavior of a double-Gaussian fluid displaying water-like features: Pair potentials that are bounded at the origin provide an accurate\ndescription of the effective interaction for many systems of dissolved soft\nmacromolecules (e.g., flexible dendrimers). Using numerical free-energy\ncalculations, we reconstruct the equilibrium phase diagram of a system of\nparticles interacting through a potential that brings together a Gaussian\nrepulsion with a much weaker Gaussian attraction, close to the thermodynamic\nstability threshold. Compared to the purely-repulsive model, only the reentrant\nbranch of the melting line survives, since for lower densities solidification\nis overridden by liquid-vapor separation. As a result, the phase diagram of the\nsystem recalls that of water up to moderate (i.e., a few tens MPa) pressures.\nUpon superimposing a suitable hard core on the double-Gaussian potential, a\nfurther transition to a more compact solid phase is induced at high pressure,\nwhich might be regarded as the analog of the ice I to ice III transition in\nwater."
    },
    {
        "anchor": "Enhancement of the Rate of Surface Reactions by Elasto-capillary Effect: Rate of a reaction is enhanced by increase in temperature, partial pressure\nor the concentration of reactants, and/or via use of a catalyst or an enzyme.\nWhereas the former increases the probability of collision rate between\ndifferent molecules, the latter provides an alternate reaction path that\ndiminishes the activation energy barrier for reaction, both effects increase\nthe reaction rate. The deformability of the substrate on which a reaction\noccurs is not known to affect this rate. In contrast, by carrying out reduction\nof Gold and Silver salt on soft, crosslinked layers of poly(dimethylsiloxane)\n(PDMS), we show here that surface tension driven deformation of the solid too\ncan increase the reaction rate. The PDMS contains SiH groups as organosilanes\nwhich reduces the salt thereby producing the corresponding metallic\nnano-particles. When an aqueous solution of the salt is dispensed as a sessile\ndrop on a sufficiently soft PDMS layer, nano-particles get generated at ~3\ntimes the rate over which when the salt solution is dispensed as a pool on the\nsame surface. Unlike the pool, the drop has a three-phase contact line, where\nit pulls up the solid forming a ridge. By balancing the resultant surface\nstresses at the vicinity of this ridge, we have estimated the excess surface\nfree energy associated with it. We show that this excess energy can diminish\nthe activation energy barrier and increase the reaction rate to the extent that\nwould have been achieved by increasing the reaction temperature by over 30o C.",
        "positive": "Molecular dynamics study of the linear viscoelastic shear and bulk\n  relaxation moduli of poly(tetramethylene oxide) (PTMO): Here we report the linear viscoelastic properties of amorphous\npoly(tetramethylene oxide) (PTMO), which is one of the key components in\nsynthesizing segmented polyurethane (PU) elastomers. The temperature and\nmolecular weight dependent viscoelastic behavior is investigated in detail by\ncomputing the shear relaxation modulus G(t) and the bulk relaxation modulus\nK(t), using the Green-Kubo relationship with correlation function. Our results\nprovide new data for PTMO melt from the united atom model and also extend the\nexisting knowledge of viscoelastic properties of polymers in general. The\npredicted viscoelastic behavior range is shifted on a master curve using the\ntime-temperature superposition principle (TTSP) with horizontal and vertical\nshift factors. The emerging shift factors agree with the Williams-Landel-Ferry\n(WLF) equation. For the validation of the united-atom model of PTMO using the\nTraPPE-UA force field we explored the transport properties and observed a\nposition-dependent diffusion dynamics throughout the polymer chain, which\nsubsequently influences the scaling laws for chain dynamics. These findings are\ndiscussed in terms of emerging experimental evidence on position dependent\ndisplacement for different chain portions along the chain length."
    },
    {
        "anchor": "Adsorption of a semiflexible polymer onto interfaces and surfaces: We consider the adsorption of a semiflexible polymer chain onto interfaces\nand surfaces by using the differential equation of the distribution function\n$G(R,L)$ of the end-to-end distance $R$, which is associated with the moment\nexpansion of the latter. We present the results of the approximative treatment\nconsisting of taking into account the 2nd and 4th moments in the differential\nequation for $G(R,L)$. The essential features of adsorption of the semiflexible\npolymer are: {\\it i}) the existence of a new local length scale, which results\nin two-exponential decay of the monomer density of adsorbed polymer; {\\it ii})\nthe binding of the semiflexible polymer is weaker than that for flexible one\nfor both interface and wall. The approximative theory presented is restricted\nto the regime of weak adsorption, where the effect of the rodlike behavior of\nthe polymer on small scales is weak.",
        "positive": "Density of States for HP Lattice Proteins: The density of states contains all informations on energetic quantities of a\nstatistical system, such as the mean energy, free energy, entropy, and specific\nheat. As a specific application, we consider in this work a simple lattice\nmodel for heteropolymers that is widely used for studying statistical\nproperties of proteins. For short chains, we have derived exact results from\nconformational enumeration, while for longer ones we developed a multicanonical\nMonte Carlo variant of the nPERM-based chain growth method in order to directly\nsimulate the density of states. For simplification, only two types of monomers\nwith respective hydrophobic (H) and polar (P) residues are regarded and only\nthe next-neighbour interaction between hydrophobic monomers, being nonadjacent\nalong the chain, is taken into account. This is known as the HP model for the\nfolding of lattice proteins."
    },
    {
        "anchor": "Molecular theory of hydrophobic mismatch between lipids and peptides: Effects of the mismatch between the hydrophobic length, d, of transmembrane\nalpha helices of integral proteins and the hydrophobic thickness, D_h, of the\nmembranes they span are studied theoretically utilizing a microscopic model of\nlipids. In particular, we examine the dependence of the period of a lamellar\nphase on the hydrophobic length and volume fraction of a rigid, integral,\npeptide. We find that the period decreases when a short peptide, such that\nd<D_h, is inserted. More surprising, we find that the period increases when a\nlong peptide, such that d>D_h, is inserted. The effect is due to the\nreplacement of extensible lipid tails by rigid peptide. As the peptide length\nis increased, the lamellar period continues to increase, but at a slower rate,\nand can eventually decrease. The amount of peptide which fails to incorporate\nand span the membrane increases with the magnitude of the hydrophobic mismatch\n|d-D_h|. We explicate these behaviors which are all in accord with experiment.\nPredictions are made for the dependence of the tilt of a single trans-membrane\nalpha helix on hydrophobic mismatch and helix density.",
        "positive": "Study of Nematic Isotropic Transition: High accuracy Monte Carlo study has been performed in the modified planar\nLebwohl Lasher model containing and interaction, where and are second and\nfourth order Legendre polynomial having three-dimensional spin. Weakly First\norder Nematic to Isotropic phase transition is observed using this model.\nExtensive Monte Carlo simulations using Wolff algorithm are performed to\ninvestigate the average energy, order parameter, ordering susceptibility,\nentropy and specific heat near phase transition. Transition temperature is also\nestimated."
    },
    {
        "anchor": "Attraction tames two-dimensional melting: from continuous to\n  discontinuous transitions: Two-dimensional systems may admit a hexatic phase and hexatic-liquid\ntransitions of different natures. The determination of their phase diagrams\nproved challenging, and indeed those of hard-disks, hard regular polygons, and\ninverse power-law potentials, have been only recently clarified. In this\ncontext, the role of attractive forces is currently speculative, despite their\nprevalence at both the molecular and colloidal scale. Here we demonstrate, via\nnumerical simulations, that attraction promotes a discontinuous melting\nscenario with no hexatic phase. At high-temperature, Lennard-Jones particles\nand attractive polygons follow the shape-dominated melting scenario observed in\nhard-disks and hard polygons, respectively. Conversely, all systems melt via a\nfirst-order transition with no hexatic phase at low temperature, where\nattractive forces dominate. The intermediate temperature melting scenario is\nshape-dependent. Our results suggest that, in colloidal experiments, the\ntunability of the strength of the attractive forces allows for the observation\nof different melting scenario in the same system.",
        "positive": "Active Brownian Equation of State: Metastability and Phase Coexistence: As a result of the competition between self-propulsion and excluded volume\ninteractions, purely repulsive self-propelled spherical particles undergo a\nmotility-induced phase separation (MIPS). We carry out a systematic\ncomputational study, considering several interaction potentials, systems\nconfined by hard walls or with periodic boundary conditions, and different\ninitial protocols. This approach allows us to identify that, despite its\nnon-equilibrium nature, the equations of state of Active Brownian Particles\n(ABP) across MIPS verify the characteristic properties of first-order\nliquid-gas phase transitions, meaning, equality of pressure of the coexisting\nphases once a nucleation barrier has been overcome and, in the opposite case,\nhysteresis around the transition as long as the system remains in the\nmetastable region. Our results show that the equations of state of ABPs\nquantitatively account for their phase behaviour, providing a firm basis to\ndescribe MIPS as an equilibrium-like phase transition."
    },
    {
        "anchor": "Structural diversity in electrohydrodynamically driven active and\n  organized liquid states: Spontaneous emergence of organized states in materials driven by\nnon-equilibrium conditions is of significant fundamental and technological\ninterest. In many cases, the organized states are complex, hence, with some\nwell-studied exceptions, their emergence is challenging to predict. In this\narticle, we show that an unexpectedly diverse collection of dissipative\norganized states can emerge in a simple biphasic system consisting of two\nliquids under planar confinement. We drive the liquid-liquid interface, which\nis held together by capillary forces, out of thermodynamic equilibrium using DC\nelectrohydrodynamic shearing. As a result, the interface goes through multiple\nspontaneous symmetry breakings, leading to various organized non-equilibrium\nstates. First, at low shearing, the shear-deformed interface becomes unstable\nand a 1D quasi-static corrugation pattern emerges. At slightly higher shearing,\nwe observe topological changes that lead to emergence of active self-propulsive\nfluidic filaments and filament networks, as well as ordered bicontinuous\nfluidic lattices. Finally, the system transitions into active self-propulsive\ndroplets, quasi-stationary dissipating polygonal and toroidal droplets, and\nultimately to a chaotic active emulsion of non-coalescing droplets with complex\ninteractions. Interestingly, this single system captures many features from\ncontinuum non-equilibrium pattern formation and discrete active particles,\nwhich are often considered separate fields of study. The diversity of observed\ndissipative organized states is exceptional and points towards many new avenues\nin the study of electrohydrodynamics, capillary phenomena, non-equilibrium\npattern formation, and active materials.",
        "positive": "Erosion patterns in a sediment layer: We report here on a laboratory-scale experiment which reproduces a rich\nvariety of natural patterns with few control parameters. In particular, we\nfocus on intriguing rhomboid structures often found on sandy shores and flats.\nWe show that the standard views based on water surface waves come short to\nexplain the phenomenon and we evidence a new mechanism based on a mud avalanche\ninstability."
    },
    {
        "anchor": "Evolution of nematic and ferromagnetic ordering in suspensions of\n  magnetic nanoplatelets: Suspensions of magnetic nanoplatelets in isotropic solvents are very\ninteresting examples of ferrofluids. It has been shown that above a certain\nconcentration {\\Phi}NI such suspensions form a ferromagnetic nematic phase,\nwhich makes this system a unique example of a dipolar fluid. The formation of a\nnematic phase is driven by anisotropic electrostatic and long-range dipolar\nmagnetic interactions. Here, we present studies of the evolution of short range\npositional and orientational magnetic order in the suspensions with volume\nfractions below and above {\\Phi}NI, using small angle neutron scattering\n(SANS). The results show that in the absence of an external magnetic field,\nshort range positional and orientational order already exist at relatively low\nvolume fractions. Polarized SANS revealed that the contribution of\nferromagnetic ordering to the formation of the nematic phase is significant.\nThe ferromagnetic correlations can be qualitatively explained by a simple\nmodel, which takes into account anisotropic screened electrostatic and dipolar\nmagnetic interactions.",
        "positive": "Quincke oscillations of colloids at planar electrodes: Dielectric particles in weakly conducting fluids rotate spontaneously when\nsubject to strong electric fields. Such Quincke rotation near a plane electrode\nleads to particle translation that enables physical models of active matter.\nHere, we show that Quincke rollers can also exhibit oscillatory dynamics,\nwhereby particles move back and forth about a fixed location. We explain how\noscillations arise for micron-scale particles commensurate with the thickness\nof a field-induced boundary layer in the nonpolar electrolyte. This work\nenables the design of colloidal oscillators."
    },
    {
        "anchor": "Setting the pace of microswimmers: when increasing viscosity speeds up\n  self-propulsion: It has long been known that some microswimmers seem to swim\ncounter-intuitively faster when the viscosity of the surrounding fluid is\nincreased, whereas others slow down. This conflicting dependence of the\nswimming velocity on the viscosity is poorly understood theoretically. Here we\nexplain that any mechanical microswimmer with an elastic degree of freedom in a\nsimple Newtonian fluid can exhibit both kinds of response to an increase in the\nfluid viscosity for different viscosity ranges, if the driving is weak. The\nvelocity response is controlled by a single parameter $\\varGamma$, the ratio of\nthe relaxation time of the elastic component of the swimmer in the viscous\nfluid and the swimming stroke period. This defines two velocity-viscosity\nregimes, which we characterize using the bead-spring microswimmer model and\nanalyzing the different forces acting on the parts of this swimmer. The\nanalytical calculations are supported by lattice-Boltzmann simulations, which\naccurately reproduce the two velocity regimes for the predicted values of\n$\\varGamma$.",
        "positive": "Soft wetting with (a)symmetric Shuttleworth effect: The wetting of soft polymer substrates brings in multiple complexities as\ncompared to the wetting on rigid substrates. The contact angle of the liquid is\nno longer governed by Young's law, but is affected by the substrate's bulk and\nsurface deformations. On top of that, elastic interfaces exhibit a surface\nenergy that depends on how much they are stretched -- a feature known as the\nShuttleworth effect (or as surface-elasticity). Here we present two models by\nwhich we explore the wetting of drops in the presence of a strong Shuttleworth\neffect. The first model is macroscopic in character and consistently accounts\nfor large deformations via a neo-Hookean elasticity. The second model is based\non a mesoscopic description of wetting, using a reduced description of the\nsubstrate's elasticity. While the second model is more empirical in terms of\nthe elasticity, it enables a gradient dynamics formulation for soft wetting\ndynamics. We provide a detailed comparison between the equilibrium states\npredicted by the two models, from which we deduce robust features of soft\nwetting in the presence of a strong Shuttleworth effect. Specifically, we show\nthat the (a)symmetry of the Shuttleworth effect between the \"dry\" and \"wet\"\nstates governs horizontal deformations in the substrate. Our results are\ndiscussed in the light of recent experiments on the wettability of stretched\nsubstrates."
    },
    {
        "anchor": "Compact reconfigurable kirigami: Kirigami involves cutting a flat, thin sheet that allows it to morph from a\nclosed, compact configuration into an open deployed structure via coordinated\nrotations of the internal tiles. By recognizing and generalizing the geometric\nconstraints that enable this art form, we propose a design framework for\ncompact reconfigurable kirigami patterns, which can morph from a closed and\ncompact configuration into a deployed state conforming to any prescribed target\nshape, and subsequently be contracted into a different closed and compact\nconfiguration. We further establish a condition for producing kirigami patterns\nwhich are reconfigurable and rigid deployable allowing us to connect the\ncompact states via a zero-energy family of deployed states. All together, our\ninverse design framework lays out a new path for the creation of shape-morphing\nmaterial structures.",
        "positive": "Multiscale polar theory of microtubule and motor-protein assemblies: Microtubules and motor proteins are building blocks of self-organized\nsubcellular biological structures such as the mitotic spindle and the\ncentrosomal microtubule array. These same ingredients can form new \"bioactive\"\nliquid-crystalline fluids that are intrinsically out of equilibrium and which\ndisplay complex flows and defect dynamics. It is not yet well understood how\nmicroscopic activity, which involves polarity-dependent interactions between\nmotor proteins and microtubules, yields such larger scale dynamical structures.\nIn our multiscale theory, Brownian dynamics simulations of polar microtubule\nensembles driven by crosslinking motors allow us to study microscopic\norganization and stresses. Polarity sorting and crosslink relaxation emerge as\ntwo polar-specific sources of active destabilizing stress. On larger length\nscales, our continuum Doi-Onsager theory captures the hydrodynamic flows\ngenerated by polarity-dependent active stresses. The results connect local\npolar structure to flow structures and defect dynamics."
    },
    {
        "anchor": "Power fluctuations in sheared amorphous materials: A minimal model: The importance of mesoscale fluctuations in flowing amorphous materials is\nwidely accepted, without a clear understanding of their role. We propose a\nmean-field elastoplastic model that admits both stress and strain-rate\nfluctuations, and investigate the character of its power distribution under\nsteady shear flow. The model predicts the suppression of negative power\nfluctuations near the liquid-solid transition; the existence of a fluctuation\nrelation in limiting regimes but its replacement in general by\nstretched-exponential power-distribution tails; and a crossover between two\ndistinct mechanisms for negative power fluctuations in the liquid and the\nyielding solid phases. We connect these predictions with recent results from\nparticle-based, numerical micro-rheological experiments.",
        "positive": "Phase equilibria and glass transition in colloidal systems with\n  short-ranged attractive interactions. Application to protein crystallization: We have studied a model of a complex fluid consisting of particles\ninteracting through a hard core and a short range attractive potential of both\nYukawa and square-well form. Using a hybrid method, including a self-consistent\nand quite accurate approximation for the liquid integral equation in the case\nof the Yukawa fluid, perturbation theory to evaluate the crystal free energies,\nand mode-coupling theory of the glass transition, we determine both the\nequilibrium phase diagram of the system and the lines of equilibrium between\nthe supercooled fluid and the glass phases. For these potentials, we study the\nphase diagrams for different values of the potential range, the ratio of the\nrange of the interaction to the diameter of the repulsive core being the main\ncontrol parameter. Our arguments are relevant to a variety of systems, from\ndense colloidal systems with depletion forces, through particle gels,\nnano-particle aggregation, and globular protein crystallization."
    },
    {
        "anchor": "The Link Between Packing Morphology and the Distribution of Contact\n  Forces and Stresses in Packings of Highly Non-Convex Particles: An external load on a particle packing is distributed internally through a\nheterogeneous network of particle contacts. This contact force distribution\ndetermines the stability of the particle packing and the resulting structure.\nHere, we investigate the homogeneity of the contact force distribution in\npackings of highly non-convex particles both in two-dimensional (2D) and\nthree-dimensional (3D) packings. A newly developed discrete element method is\nused to model packings of non-convex particles of varying sphericity. Our\nresults establish that in 3D packings the distribution of the contact forces in\nthe normal direction becomes increasingly heterogeneous with decreasing\nparticle sphericity. However, in 2D packings the contact force distribution is\nindependent of particle sphericity, indicating that results obtained in 2D\npackings cannot be extrapolated readily to 3D packings. Radial distribution\nfunctions (RDFs) show that the crystallinity in 3D packings decreases with\ndecreasing particle sphericity. We link the decreasing homogeneity of the\ncontact force distributions to the decreasing crystallinity of 3D packings.\nThese findings are complementary to the previously observed link between the\nheterogeneity of the contact force distribution and a decreasing packing\ncrystallinity due to an increasing polydispersity of spherical particles.",
        "positive": "Metachronal waves in the flagellar beating of $Volvox$ and their\n  hydrodynamic origin: Groups of eukaryotic cilia and flagella are capable of coordinating their\nbeating over large scales, routinely exhibiting collective dynamics in the form\nof metachronal waves. The origin of this behaviour -- possibly influenced by\nboth mechanical interactions and direct biological regulation -- is poorly\nunderstood, in large part due to lack of quantitative experimental studies.\nHere we characterise in detail flagellar coordination on the surface of the\nmulticellular alga $Volvox~carteri$, an emerging model organism for flagellar\ndynamics. Our studies reveal for the first time that the average metachronal\ncoordination observed is punctuated by periodic phase defects during which\nsynchrony is partial and limited to specific groups of cells. A minimal model\nof hydrodynamically coupled oscillators can reproduce semi-quantitatively the\ncharacteristics of the average metachronal dynamics, and the emergence of\ndefects. We systematically study the model's behaviour by assessing the effect\nof changing intrinsic rotor characteristics, including oscillator stiffness and\nthe nature of their internal driving force, as well as their geometric\nproperties and spatial arrangement. Our results suggest that metachronal\ncoordination follows from deformations in the oscillators' limit cycles induced\nby hydrodynamic stresses, and that defects result from sufficiently steep local\nbiases in the oscillators' intrinsic frequencies. Additionally, we find that\nrandom variations in the intrinsic rotor frequencies increase the robustness of\nthe average properties of the emergent metachronal waves."
    },
    {
        "anchor": "Effect of Cationic and Anionic Surfactants on the Application of Calcium\n  Carbonate Nanoparticles in Paper Coating: Modification of calcium carbonate particles with surfactant significantly\nimproves the properties of the calcium carbonate coating on paper. Unmodified\nand CTAB and oleate-modified calcium carbonate nanoparticles were prepared\nusing the wet carbonation technique for paper coating. CTAB (cationic\nsurfactant) and sodium oleate (anionic surfactant) were used to modify the\nsize, morphology, and surface properties of the precipitated nanoparticles. The\nobtained particles were characterized by XRD, FT-IR spectroscopy, zeta\npotential measurements, TGA and TEM. Coating colors were formulated from the\nprepared unmodified and modified calcium carbonates and examined by creating a\nthin coating layer on reference paper. The effect of calcium carbonate particle\nsize and surface modification on paper properties, such as coating thickness,\ncoating weight, surface roughness, air permeability, brightness, whiteness,\nopacity, and hydrophobicity, were investigated and compared with GCC calcium\ncarbonate-coated papers. The obtained calcium carbonate nanoparticles are in\nthe calcite phase. The morphology of the prepared calcium carbonate\nnanoparticles is rhombohedral, and the average particle diameter is <100 nm.\nCompared to commercial GCC, the use of unmodified and CTAB- and oleate-modified\ncalcium carbonate nanoparticles in paper coating improves the properties of\npaper. The highest measured paper properties were observed for paper coated\nwith oleate-modifed nanoparticles, where an increase in smoothness (decrease in\npaper roughness) (+23%), brightness (+1.3%), whiteness (+2.8%), and opacity\n(+2.3%) and a decrease in air permeability (-26%) was obtained with 25% less\ncoat weight. The WCA at 10 min was about 112{\\deg} for the paper coated with\noleate-modified nanoparticles and 42{\\deg} for paper coated with CTAB-modified\nnanoparticles compared to 104{\\deg} for GCC-coated paper.",
        "positive": "Low-frequency oscillations in narrow vibrated granular systems: We present simulations and a theoretical treatment of vertically vibrated\ngranular media. The systems considered are confined in narrow\nquasi-two-dimensional and quasi-one-dimensional (column) geometries, where the\nvertical extension of the container is much larger than both horizontal\nlengths. The additional geometric constraint present in the column setup\nfrustrates the convection state that is normally observed in wider geometries.\nThis makes it possible to study collective oscillations of the grains with a\ncharacteristic frequency that is much lower than the frequency of energy\ninjection. The frequency and amplitude of these oscillations are studied as a\nfunction of the energy input parameters and the size of the container. We\nobserve that, in the quasi-two-dimensional setup, low-frequency oscillations\nare present even in the convective regime. This suggests that they may play a\nsignificant role in the transition from a density inverted state to convection.\nTwo models are also presented; the first one, based on Cauchy's equations, is\nable to predict with high accuracy the frequency of the particles' collective\nmotion. This first principles model requires a single input parameter, i.e, the\ncentre of mass of the system. The model shows that a sufficient condition for\nthe existence of the low-frequency mode is an inverted density profile with\ndistinct low and high density regions, a condition that may apply to other\nsystems too. The second, simpler model just assumes an harmonic oscillator like\nbehaviour and, using thermodynamic arguments, is also able to reproduce the\nobserved frequencies with high accuracy."
    },
    {
        "anchor": "Emergent Nonlocal Combinatorial Design Rules for Multimodal\n  Metamaterials: Combinatorial mechanical metamaterials feature spatially textured soft modes\nthat yield exotic and useful mechanical properties. While a single soft mode\noften can be rationally designed by following a set of tiling rules for the\nbuilding blocks of the metamaterial, it is an open question what design rules\nare required to realize multiple soft modes. Multimodal metamaterials would\nallow for advanced mechanical functionalities that can be selected on the fly.\nHere we introduce a transfer matrix-like framework to design multiple soft\nmodes in combinatorial metamaterials composed of aperiodic tilings of building\nblocks. We use this framework to derive rules for multimodal designs for a\nspecific family of building blocks. We show that such designs require a large\nnumber of degeneracies between constraints, and find precise rules on the real\nspace configuration that allow such degeneracies. These rules are significantly\nmore complex than the simple tiling rules that emerge for single-mode\nmetamaterials. For the specific example studied here, they can be expressed as\nlocal rules for tiles composed of pairs of building blocks in combination with\na nonlocal rule in the form of a global constraint on the type of tiles that\nare allowed to appear together anywhere in the configuration. This nonlocal\nrule is exclusive to multimodal metamaterials and exemplifies the complexity of\nrational design of multimode metamaterials. Our framework is a first step\ntowards a systematic design strategy of multimodal metamaterials with spatially\ntextured soft modes.",
        "positive": "Cooling under applied stress rejuvenates amorphous alloys and enhances\n  their ductility: The effect of tensile stress applied during cooling of binary glasses on the\npotential energy states and mechanical properties is investigated using\nmolecular dynamics simulations. We study the three-dimensional binary mixture\nthat was first annealed near the glass transition temperature and then rapidly\ncooled under tension into the glass phase. It is found that at larger values of\nthe applied stress, the liquid glass former freezes under higher strain and its\npotential energy is enhanced. For a fixed cooling rate, the maximum tensile\nstress that can be applied during cooling is reduced upon increasing initial\ntemperature above the glass transition point. We also show that the amorphous\nstructure of rejuvenated glasses is characterized by an increase in the number\nof contacts between smaller type atoms. Furthermore, the results of tensile\ntests demonstrate that the elastic modulus and the peak value of the stress\novershoot are reduced in glasses prepared at larger applied stresses and higher\ninitial temperatures, thus indicating enhanced ductility. These findings might\nbe useful for the development of processing and fabrication methods to improve\nplasticity of bulk metallic glasses."
    },
    {
        "anchor": "Effective dynamics of twisted and curved scroll waves using virtual\n  filaments: Scroll waves are three-dimensional excitation patterns that rotate around a\ncentral filament curve; they occur in many physical, biological and chemical\nsystems. We explicitly derive the equations of motion for scroll wave filaments\nin reaction-diffusion systems with isotropic diffusion up to third order in the\nfilament's twist and curvature. The net drift components define at every\ninstance of time a virtual filament which lies close to the instantaneous\nfilament. Importantly, virtual filaments obey simpler, time-independent laws of\nmotion which we analytically derive here and illustrate with numerical\nexamples. Stability analysis of scroll waves is performed using virtual\nfilaments, showing that filament curvature and twist add as quadratic terms to\nthe nominal filament tension. Applications to oscillating chemical reactions\nand cardiac tissue are discussed.",
        "positive": "Uniting Superhydrophobic, Superoleophobic and Lubricating Fluid Infused\n  Slippery Behavior on Copper Oxide Nano-structured Substrates: Copper oxide nanostructures with spherical (0D), needle (1D) and hierarchical\ncauliflower (3D) morphologies are used to demonstrate superhydrophobic,\nsuperoleophobic and slippery behavior. These nanostructures are synthesized on\ngalvanized steel substrates using a simple chemical bath deposition method by\ntuning precursor concentration. Subsequent coating of low surface energy\npolymer, polydimethylsiloxane, results in superhydrophobicity with water\ncontact angle ~160(2){\\deg} and critical sliding angle ~2{\\deg}. When\nfunctionalized with low-surface energy perfluoroalkyl silane, these surfaces\ndisplay high repellency for low surface tension oils and hydrocarbons. Among\nthem, the hierarchical cauliflower morphology exhibits better re-entrant\nstructure thus show the best superoleophobicity with 149{\\deg} contact angle\nfor dodecane having surface tension 25.3 mNm-1. If these nanostructured\nsubstrates are infused with lubricant Silicone oil, they show excellent\nslippery behavior for water drops. Due to the lubricating nature of Silicone\noil, the Silicone oil infused slippery surfaces (SOIS) show low contact angle\nhysteresis (~2{\\deg}) and critical tilt angle (~2{\\deg}). The hierarchical\ncauliflower nanostrcuture exhibit better slippery characteristics and stability\ncompared to the other nanostructured surfaces."
    },
    {
        "anchor": "Negative Poisson's ratio and semi-soft elasticity of smectic-C liquid\n  crystal elastomers: Models of smectic-C liquid crystal elastomers predict that it can display\nsoft elasticity, in which the shape of the elastomer changes at no energy cost.\nThe amplitude of the soft mode and the accompanying shears are dependent on the\norientation of the layer normal and the director with respect to the stretch\naxis. We demonstrate that in some geometries the director is forced to rotate\nperpendicular to the stretch axis, causing lateral expansion of the sample; a\nnegative Poisson's ratio. Current models do not include the effect of\nimperfections that must be present in the physical sample. We investigate the\neffect of a simple model of these imperfections on the soft modes in monodomain\nsmectic-C elastomers in a variety of geometries. When stretching parallel to\nthe layer normal (with imposed strain) the elastomer has a negative stiffness\nonce the director starts to rotate. We show that this is a result of the\nnegative Poisson's ratio in this geometry through a simple scalar model.",
        "positive": "On the stability of 2 \\sqrt{2} x 2 \\sqrt{2} oxygen ordered\n  superstructures in YBa2Cu3O6+x: We have compared the ground-state energy of several observed or proposed \" 2\n\\sqrt{2} x 2 \\sqrt{2} oxygen (O) ordered superstructures \" (from now on HS),\nwith those of \"chain superstructures\" (CS) (in which the O atoms of the basal\nplane are ordered in chains), for different compositions x in YBa2Cu3O6+x. The\nmodel Hamiltonian contains i) the Madelung energy, ii) a term linear in the\ndifference between Cu and O hole occupancies which controls charge transfer,\nand iii) covalency effects based on known results for $t-J$ models in one and\ntwo dimensions. The optimum distribution of charge is determined minimizing the\ntotal energy, and depends on two parameters which are determined from known\nresults for x=1 and x=0.5. We obtain that on the O lean side, only CS are\nstable, while for x=7/8, a HS with regularly spaced O vacancies added to the\nx=1 structure is more stable than the corresponding CS for the same x. We find\nthat the detailed positions of the atoms in the structure, and long-range\nCoulomb interactions, are crucial for the electronic structure, the mechanism\nof charge transfer, the stability of the different phases, and the possibility\nof phase separation."
    },
    {
        "anchor": "Bioinspired rational design of multi-material 3D printed soft-hard\n  interfaces: Durable interfacing of hard and soft materials is a major design challenge\ncaused by the ensuing stress concentrations. In nature, soft-hard interfaces\nexhibit remarkable mechanical performance, with failures rarely happening at\nthe interface but in the hard or soft material. This superior performance is\nmechanistically linked to such design features as hierarchical structures,\nmultiple types of interlocking, and functional gradients. Here, we mimic these\nstrategies to design efficient soft-hard interfaces using voxel-based\nmulti-material 3D printing. We designed several types of soft-hard interfaces\nwith interfacial functional gradients and various types of bio-inspired\ninterlocking mechanisms. The geometrical designs were based on triply periodic\nminimal surfaces (i.e., octo, diamond, and gyroid), collagen-like triple\nhelices, and randomly distributed particles. We utilized a combination of the\nfinite element method and experimental techniques, including uniaxial tensile\ntests, quad-lap shear tests, and full-field strain measurement using digital\nimage correlation, to characterize the mechanical performance of different\ngroups. The analysis of the best performing designs (i.e., the gyroid,\ncollagen, and particle designs) suggests that smooth interdigitated\nconnections, compliant gradient transitions, and either decreasing or\nconstraining the strain concentrations regions between the hard and soft phases\nled to simultaneously strong and tough interfaces. Increasing the gradient\nlength was only beneficial when the resulting interface geometry reduced strain\nconcentrations (e.g., in collagen and particles). Combining the gyroid-based\narchitecture with a random distribution of particles yielded the\nbest-performing soft-hard interface, with strengths approaching the upper limit\nof the possible strengths and up to 50% toughness enhancement as compared to\nthe control group.",
        "positive": "Scaling of Traction Forces with Size of Cohesive Cell Colonies: To understand how the mechanical properties of tissues emerge from\ninteractions of multiple cells, we measure traction stresses of cohesive\ncolonies of 1-27 cells adherent to soft substrates. We find that traction\nstresses are generally localized at the periphery of the colony and the total\ntraction force scales with the colony radius. For large colony sizes, the\nscaling appears to approach linear, suggesting the emergence of an apparent\nsurface tension of order 1E-3 N/m. A simple model of the cell colony as a\ncontractile elastic medium coupled to the substrate captures the spatial\ndistribution of traction forces and the scaling of traction forces with the\ncolony size."
    },
    {
        "anchor": "Isobaric-isothermal molecular dynamics computer simulations of the\n  properties of water-1,2-dimethoxyethane model mixtures: Isothermal-isobaric molecular dynamics simulations have been performed to\nexamine a broad set of properties of the model water-1,2-dimethoxyethane (DME)\nmixture as a function of composition. The SPC-E and TIP4P-Ew water models and\nthe modified TraPPE model for DME were applied. Our principal focus was to\nexplore the trends of behaviour of the structural properties in terms of the\nradial distribution functions, coordination numbers and number of hydrogen\nbonds between molecules of different species, and of conformations of DME\nmolecules. Thermodynamic properties, such as density, molar volume, enthalpy of\nmixing and heat capacity at constant pressure have been examined. Finally, the\nself-diffusion coefficients of species and the dielectric constant of the\nsystem were calculated and analyzed.",
        "positive": "Thermophoretic motion of a charged single colloidal particle: We calculate the thermophoretic drift of a charged single colloidal particle\nwith hydrodynamically slipping surface immersed in an electrolyte solution in\nresponse to a small temperature gradient. Here, we rely on a linearized\nhydrodynamic approach for the fluid flow and the motion of the electrolyte ions\nwhile keeping the full nonlinearity of the Poisson-Boltzmann equation of the\nunperturbed system to account for possible large surface charging. The partial\ndifferential equations are transformed into a coupled set of ordinary\ndifferential equations in linear response. Numerical solutions are elaborated\nfor parameter regimes of small and large Debye shielding and different\nhydrodynamic boundary conditions encoded in a varying slip length. Our results\nare in good agreement with predictions from recent theoretical work and\nsuccessfully describe experimental observations on thermophoresis of DNA. We\nalso compare our numerical results with experimental data on polystyrene beads."
    },
    {
        "anchor": "UV-Manipulation of Order and Macroscopic Shape in Nematic Elastomers: A range of monodomain nematic liquid crystal elastomers containing differing\nproportions of photo-isomerisable mesogenic moieties, which turn from a\nrod-like to a kinked shape upon ultraviolet (UV) irradiation, was studied.\nDepending on the proportion and positional role of the photo-sensitive groups\nin the crosslinked polymer network, different types and magnitudes of response\nwere found. The principle consequence of such photo-isomerisation is the\ndestabilisation of the nematic phase, whose order parameter depends on\ntemperature in a near-critical fashion. Accordingly, the effect of\nUV-irradiation is dramatically enhanced near the critical temperature, with the\nassociated reduction in the nematic order parameter manifesting as a change in\nthe macroscopic shape of the elastomer samples, producing a large uniaxial\ncontraction. Theoretical analysis of this phenomenon gives a good quantitative\nagreement with experiment.",
        "positive": "An agent-based framework of active matter with applications in\n  biological and social systems: Active matter, as other types of self-organizing systems, relies on the\ntake-up of energy that can be used for different actions, such as active motion\nor structure formation. Here we provide an agent-based framework to model these\nprocesses at different levels of organization, physical, biological and social,\nusing the same dynamic approach. Driving variables describe the take-up,\nstorage and conversion of energy, whereas driven variables describe the energy\nconsuming activities. The stochastic dynamics of both types of variables follow\na modified Langevin equation. Additional non-linear functions allow to encode\nsystem-specific hypotheses about the relation between driving and driven\nvariables. To demonstrate the applicability of this framework, we recast a\nnumber of existing models of Brownian agents and Active Brownian Particles.\nSpecifically, active motion, clustering and self-wiring of networks based on\nchemotactic interactions, online communication and polarization of opinions\nbased on emotional influence are discussed. The framework allows to obtain\ncritical parameters for active motion and the emergence of collective\nphenomena. This highlights the role of energy take-up and dissipation in\nobtaining different dynamic regimes."
    },
    {
        "anchor": "Folding of the apolipoprotein A1 driven by the salt concentration as a\n  possible mechanism to improve cholesterol trapping: The folding of the cholesterol trapping apolipoprotein A1 in aqueous solution\nat increasing ionic strength is studied using atomically detailed molecular\ndynamics simulations. We calculate various structural properties to\ncharacterize the conformation of the protein, such as the radius of gyration,\nthe radial distribution function and the end to end distance. Additionally we\nreport information using tools specifically tailored for the characterization\nof proteins, such as the mean smallest distance matrix and the Ramachandran\nplot. We find that two qualitatively different configurations of this protein\nare preferred, one where the protein is extended, and one where it forms loops\nor closed structures. It is argued that the latter promote the association of\nthe protein with cholesterol and other fatty acids.",
        "positive": "Thin Pyramidal Cones in Nematic Liquid Crystal: The present study investigates the arrangement of hollow pyramidal cone\nshells and their interactions with degenerate planar anchoring on the inner and\nouter surfaces of particles within the nematic host. The shell thickness is in\norder of the nematic coherence length. The numerical behavior of colloids is\ndetermined by minimizing the Landau-de Gennes free energy in the presence of\nthe Fournier surface energy and using the finite element method. Colloidal\npyramidal cones can orient parallel and perpendicular with the far director\norientation. In the parallel alignment, we found the splay director distortion\ninto the pyramid with two boojum defects at the inner and outer tips. The\ndirector shows bending distortion without defect patterns when the pyramid is\naligned perpendicularly. They induce long-range dipolar interaction and can\nform nested structures in close contact."
    },
    {
        "anchor": "K-Rb Fermi-Bose mixtures: vortical states and sag: We study a confined mixture of bosons and fermions in the quantal degeneracy\nregime with attractive boson-fermion interaction. We discuss the effect that\nthe presence of vortical states and the displacement of the trapping potentials\nmay have on mixtures near collapse, and investigate the phase stability diagram\nof the K-Rb mixture in the mean field approximation supposing in one case that\nthe trapping potentials felt by bosons and fermions are shifted from each\nother, as it happens in the presence of a gravitational sag, and in another\ncase, assuming that the Bose condensate sustains a vortex state. In both cases,\nwe have obtained an analytical expression for the fermion effective potential\nwhen the Bose condensate is in the Thomas-Fermi regime, that can be used to\ndetermine the maxima of the fermionic density. We have numerically checked that\nthe values one obtains for the location of these maxima using the analytical\nformulas remain valid up to the critical boson and fermion numbers, above which\nthe mixture collapses.",
        "positive": "Flow-Induced Draping: Crumpled paper or drapery patterns are everyday examples of how elastic\nsheets can respond to external forcing. In this Letter, we study experimentally\na novel sort of forcing. We consider a circular flexible plate clamped at its\ncenter and subject to a uniform flow normal to its initial surface. As the flow\nvelocity is gradually increased, the plate exhibits a rich variety of bending\ndeformations: from a cylindrical taco-like shape, to isometric developable\ncones with azimuthal periodicity two or three, to eventually a rolled-up\nperiod-three cone. We show that this sequence of flow-induced deformations can\nbe qualitatively predicted by a linear analysis based on the balance between\nelastic energy and pressure force work."
    },
    {
        "anchor": "3BrY nucleation: from dimers to needle-like clusters: The nucleation of 1,3,5-Tris(4-bromophenyl)- benzene (3BrY) occurs through\nthe formation of amorphous intermediates. However, a detailed experimental\ncharacterization of the structural and dynamic features of such early- stage\nprecursors is prevented by their transient nature. In this work, we apply\nmolecular mod- eling to investigate both nucleation and growth of 3BrY clusters\nfrom solution. Consistently with experimental findings, we observe that dis-\nordered clusters consisting of 10-15 monomers can spontaneously emerge from\nsolution. Such clusters are poorly ordered and can easily fluctuate in size and\nshape. When clusters grow to a larger size (up to 200 monomer units) they\ndevelop a markedly elongated morphology, reminiscent of the needle-like 3BrY\ncrystals observed experimentally. The growth process is characterized by a\ncontinuous rearrangement of ordered and disordered domains accompa- nied by a\ndynamical exchange of molecules and oligomers with the solution, in a mechanism\nresembling the self-assembly of non-covalent supra-molecular fibers.",
        "positive": "Confirmation of Anomalous Dynamical Arrest in attractive colloids: a\n  molecular dynamics study: Previous theoretical, along with early simulation and experimental, studies\nhave indicated that particles with a short-ranged attraction exhibit a range of\nnew dynamical arrest phenomena. These include very pronounced reentrance in the\ndynamical arrest curve, a logarithmic singularity in the density correlation\nfunctions, and the existence of `attractive' and `repulsive' glasses. Here we\ncarry out extensive molecular dynamics calculations on dense systems\ninteracting via a square-well potential. This is one of the simplest systems\nwith the required properties, and may be regarded as canonical for interpreting\nthe phase diagram, and now also the dynamical arrest. We confirm the\ntheoretical predictions for re-entrance, logarithmic singularity, and give the\nfirst direct evidence of the coexistence, independent of theory, of the two\ncoexisting glasses. We now regard the previous predictions of these phenomena\nas having been established."
    },
    {
        "anchor": "Stability of Designed Proteins Against Mutations: The stability of model proteins with designed sequences is assessed in terms\nof the number of sequences (obtained from the designed sequence through\nmutations), which fold into 5the ``native'' conformation. By a complete\nenumeration of the total number of sequences obtained by introducing up to 4\npoint mutations and up to 7 composition--conserving mutations (swapping of\namino acids) in a 36mers chain, it is found that there are $10^8-10^9$\nsequences which in the folding process target onto the ``native'' conformation.\nConsequently, proteins with designed sequences display a remarkable degree of\nstability and, to a large extent, of designability.",
        "positive": "The force on a body in active matter: We present a general theory for determining the force (and torque) exerted on\na boundary (or body) in active matter. The theory extends the description of\npassive Brownian colloids to self-propelled active particles and applies for\nall ratios of the thermal energy $k_BT$ to the swimmer's activity $k_sT_s =\n\\zeta U_0^2\\tau_R/6$, where $\\zeta$ is the Stokes drag coefficient, $U_0$ is\nthe swim speed and $\\tau_R$ is the reorientation time of the active particles.\nThe theory has a natural microscopic length scale over which concentration and\norientation distributions are confined near boundaries, but the microscopic\nlength does not appear in the force. The swim pressure emerges naturally and\ndominates the behavior when the boundary size is large compared to the\nswimmer's run length $\\ell = U_0\\tau_R$. The theory is used to predict the\nmotion of bodies of all sizes immersed in active matter."
    },
    {
        "anchor": "Polymorphism of stable collagen fibrils: Collagen fibrils are versatile self-assembled structures that provide\nmechanical integrity within mammalian tissues. The radius of collagen fibrils\nvary widely depending on experimental conditions \\textit{in vitro} or\nanatomical location \\textit{in vivo}. Here we explore the variety of\nthermodynamically stable fibril configurations that are available. We use a\nliquid crystal model of radial collagen fibril structure with a double-twist\ndirector field. Using a numerical relaxation method we show that two\ndimensionless parameters, the ratio of saddle-splay to twist elastic constants\n$ k_{24}/K_{22}$ and the ratio of surface tension to chiral strength\n$\\hat{\\gamma} \\equiv \\gamma/(K_{22}q)$, largely specify both the scaled fibril\nradius and the associated surface twist of equilibrium fibrils. We find that\ncollagen fibrils are the stable phase with respect to the cholesteric phase\nonly when the reduced surface tension is small, $\\hat{\\gamma} \\lesssim 0.2$.\nWithin this stable regime, collagen fibrils can access a wide range of radii\nand associated surface twists. Remarkably, we find a maximal equilibrium\nsurface twist of $0.33$ rad ($19^{\\text{o}}$). Our results are compatible with\ncorneal collagen fibrils, and we show how the large surface twist is needed to\nexplain the narrow distribution of corneal fibril radii. Conversely, we show\nhow small surface twist is required for the thermodynamic stability of tendon\nfibrils in the face of considerable polydispersity of radius.",
        "positive": "Convection of mono-disperse particles in a highly filled rotating\n  cylinder: We investigate the occurrence of spontaneous convection in a coaxial cylinder\nhighly filled with mono-disperse spheres.\n  To analyze the flow field non-invasively, initial pulses consisting of\ncolored particles are placed at equal intervals.\n  By analyzing the spatio-temporal distribution of these pulses, we obtained\naxial velocity profiles for both the surface and subsurface regions.\n  Our advection-diffusion equations with steady advection terms incorporate\nexperimentally obtained axial velocity profiles in the surface layer, while the\nrest of the components are estimated using azimuthal symmetry and volume\nconservation.\n  The validity of our model is confirmed by comparing experimental data with\nnumerical solutions for both the spatio-temporal distribution and\ncross-sectional profile of the colored particles."
    },
    {
        "anchor": "Theory and Phenomenology of Mixed Amphiphilic Aggregates: We give a short overview of existing approaches describing shapes and\nenergetics of amphiphilic aggregates. In particular, we consider recent\nexperimental data and theory in relation to mixed aggregates. We point out the\noutstanding questions deserving further investigations such as stability of\nsingle-component vesicles and size growth of mixed vesicles induced by\nmicelle-forming surfactants.",
        "positive": "Pressure and temperature dependence of solubility and surface adsorption\n  of nitrogen in the liquid hydrocarbon bodies on Titan: We have studied the pressure and temperature dependence of solubility of\nnitrogen in methane and ethane using vapor-liquid equilibrium simulations of\nbinary mixtures of nitrogen in methane and ethane for a range of pressures\nbetween 1.5 atm and 3.5 atm and temperatures between 90 K and 110 K,\nthermodynamic conditions that may exist on the Saturn's moon, Titan. We find\nthat the solubility of nitrogen in methane increases linearly with pressure\nwhile the solubility of nitrogen in ethane increases exponentially with\npressure at temperature 90 K. Solubility of nitrogen in both methane and ethane\nexhibits an exponential decrease with temperature at a pressure of 3 atm. The\nsolubility of nitrogen in methane is much larger compared to that in ethane in\nthe range of pressure and temperature studied here. Our results are in\nquantitative agreement with the available experimental measurements of the\nsolubility of nitrogen in methane and ethane. Furthermore, we find that the\nsurface adsorption of nitrogen increases with increasing pressure at\ntemperature 90 K, while the adsorption free energy increases with increasing\npressure. Moreover, we find that the surface tension decreases linearly with\npressure for both nitrogen-methane and nitrogen-ethane systems. The rate of\ndecrease of surface tension with pressure for nitrogen-ethane system is much\nlarger as compared to the nitrogen-methane system. Finally, we find that the\nabsorption of a nitrogen molecule into the liquid-phase from the interface is\ndiffusive and does not involve any appreciable energy barrier. Our results\nsuggest that homogeneous nucleation of bubbles is unlikely on Titan and the\nbubble formation in the lakes on Titan must arise from heterogeneous nucleation\nof bubbles."
    },
    {
        "anchor": "Dynamics of flexible fibers in confined shear flows at finite Reynolds\n  numbers: We carry out a numerical study on the dynamics of a single non-Brownian\nflexible fiber in two-dimensional Couette flows at finite Reynolds numbers. We\nemploy the bead-spring model of flexible fibers to extend the fluid particle\ndynamics (FPD) method that is originally developed for rigid particles in\nviscous liquids. We implement the extended FPD method using a\nmultiple-relaxation-time (MRT) scheme of the lattice Boltzmann method (LBM).\nThe numerical scheme is validated firstly by a series of benchmark simulations\nthat involve liquid-solid coupling. The method is then used to study the\ndynamics of flexible fibers in Couette flows. We only consider the highly\nsymmetric case where the fibers are placed on the symmetry center of Couette\nflows and we focus on the effects of the fiber stiffness, the confinement\nstrength, and the finite Reynolds number (from 1 to 10). A diagram of the fiber\nshape is obtained. For fibers under weak confinement and a small Reynolds\nnumber, three distinct tumbling orbits have been identified. (1) Jeffery orbits\nof rigid fibers. The fibers behave like rigid rods and tumble periodically\nwithout any visible deformation. (2) S-turn orbits of slightly flexible fibers.\nThe fiber is bent to an S-shape and is straightened again when it orients to an\nangle of around 45 degrees relative to the positive x direction. (3) S-coiled\norbits of fairly flexible fibers. The fiber is folded to an S-shape and tumbles\nperiodically and steadily without being straightened anymore during its\nrotation. Moreover, the fiber tumbling is found to be hindered by increasing\neither the Reynolds number or the confinement strength, or both.",
        "positive": "Flow and Jamming of Granular Suspensions in Foams: The drainage of particulate foams is studied under conditions where the\nparticles are not trapped individually by constrictions of the interstitial\npore space. The drainage velocity decreases continuously as the particle volume\nfraction $\\phi_{p}$ increases. The suspensions jam - and therefore drainage\nstops - for values $\\phi_{p}^{*}$ which reveal a strong effect of the particle\nsize. In accounting for the particular geometry of the foam, we show that\n$\\phi_{p}^{*}$ accounts for unusual confinement effects when the particles pack\ninto the foam network. We model quantitatively the overall behavior of the\nsuspension - from flow to jamming - by taking into account explicitly the\ndivergence of its effective viscosity at $\\phi_{p}^{*}$. Beyond the scope of\ndrainage, the reported jamming transition is expected to have a deep\nsignificance for all aspects related to particulate foams, from aging to\nmechanical properties."
    },
    {
        "anchor": "Shear Induced Pressure Determines a Reduction in Polymer Radius: Shear induced particle pressure has been measured and modelled for\nconcentrated suspensions of particles. Importantly, the significance of the\nshear induced particle pressure has not been recognized in polymer rheology.\nThe shear induced particle pressure results in an inward pressure on the\npolymer chains resulting in a shear dependent compressive force. The analytical\nform of the force balance equations that incorporate the effect of shear\ninduced particle pressure predict a reduced polymer blob size and reducing\nviscosity with increasing shear rate as has been observed experimentally. Power\nlaw behavior is found for the viscosity in accord with the general behavior\nobserved for the rheology of concentrated polymer solutions and melts.\nDiffering powers are found for the behavior depending on the concentration\nregime.",
        "positive": "Dynamical Monte Carlo Study of Equilibrium Polymers : Static Properties: We report results of extensive Dynamical Monte Carlo investigations on\nself-assembled Equilibrium Polymers (EP) without loops in good solvent. (This\nis thought to provide a good model of giant surfactant micelles.) Using a novel\nalgorithm we are able to describe efficiently both static and dynamic\nproperties of systems in which the mean chain length $\\Lav$ is effectively\ncomparable to that of laboratory experiments (up to 5000 monomers, even at high\npolymer densities). We sample up to scission energies of $E/k_BT=15$ over\nnearly three orders of magnitude in monomer density $\\phi$, and present a\ndetailed crossover study ranging from swollen EP chains in the dilute regime up\nto dense molten systems. Confirming recent theoretical predictions, the\nmean-chain length is found to scale as $\\Lav \\propto \\phi^\\alpha \\exp(\\delta\nE)$ where the exponents approach $\\alpha_d=\\delta_d=1/(1+\\gamma) \\approx 0.46$\nand $\\alpha_s = 1/2 [1+(\\gamma-1)/(\\nu d -1)] \\approx 0.6, \\delta_s=1/2$ in the\ndilute and semidilute limits respectively. The chain length distribution is\nqualitatively well described in the dilute limit by the Schulz-Zimm\ndistribution $\\cN(s)\\approx s^{\\gamma-1} \\exp(-s)$ where the scaling variable\nis $s=\\gamma L/\\Lav$. The very large size of these simulations allows also an\naccurate determination of the self-avoiding walk susceptibility exponent\n$\\gamma \\approx 1.165 \\pm 0.01$. ....... Finite-size effects are discussed in\ndetail."
    },
    {
        "anchor": "Predicting Adhesive Free Energies of Polymer--Surface Interactions with\n  Machine Learning: Polymer-surface interactions are crucial to many biological processes and\nindustrial applications. Here we propose a machine-learning method to connect a\nmodel polymer's sequence with its adhesion to decorated surfaces. We simulate\nthe adhesive free energies of $20,000$ unique coarse-grained 1D sequential\npolymers interacting with functionalized surfaces and build support vector\nregression (SVR) models that demonstrate inexpensive and reliable prediction of\nthe adhesive free energy as a function of the sequence. Our work highlights the\npromising integration of coarse-grained simulation with data-driven machine\nlearning methods for the design of new functional polymers and represents an\nimportant step toward linking polymer compositions with polymer-surface\ninteractions.",
        "positive": "Ion partitioning effect on the electrostatic interaction between two\n  charged soft surfaces: We theoretically investigate electrostatic properties between two charged\nsurfaces with a grafted polyelectrolyte layer in an aqueous electrolyte\nsolution by using the Poisson-Boltzmann approach accounting for ion\npartitioning. In order to consider the ion partitioning effect, we focus on\nchanges of electrostatic properties due to the difference in dielectric\npermittivity of the polyelectrolyte layer and the aqueous electrolyte solution.\nWe find that ion partitioning enhances electrostatic potential in the region\nbetween two charged soft surfaces and hence increases the electrostatic\ninteraction between two charged soft surfaces. Ion partitioning effect on\nosmotic pressure is enhanced not only by an increase in the thickness of\npolyelectrolyte layer and Debye length but also by a decrease in ion radius."
    },
    {
        "anchor": "Regular dendritic patterns induced by non-local time-periodic forcing: The dynamic response of dendritic solidification to spatially homogeneous\ntime-periodic forcing has been studied. Phase-field calculations performed in\ntwo dimensions (2D) and experiments on thin (quasi 2D) liquid crystal layers\nshow that the frequency of dendritic side-branching can be tuned by oscillatory\npressure or heating. The sensitivity of this phenomenon to the relevant\nparameters, the frequency and amplitude of the modulation, the initial\nundercooling and the anisotropies of the interfacial free energy and molecule\nattachment kinetics, has been explored. It has been demonstrated that besides\nthe side-branching mode synchronous with external forcing as emerging from the\nlinear Wentzel-Kramers-Brillouin analysis, modes that oscillate with higher\nharmonic frequencies are also present with perceptible amplitudes.",
        "positive": "Counterion correlations near charged surfaces: from the weak to the\n  strong coupling regime: A simple field theory approach is developed to model the properties of\ncharged, dielectric bodies and their associated counterions. This predictive\ntheory is able to accurately describe the properties of systems (as compared to\ncomputer simulation data) from the weak coupling limit, where the\nPoisson-Boltzmann theory works well, through to the strong coupling limit. In\nparticular, it is able to quantitatively describe the attraction between\nlike-charged plates and the influence of image charge interactions."
    },
    {
        "anchor": "Quantifying Spatially Heterogeneous Dynamics in Computer Simulations of\n  Glassforming Liquids: We examine the phenomenon of dynamical heterogeneity in computer simulations\nof an equilibrium, glass-forming liquid. We describe several approaches to\nquantify the spatial correlation of single-particle motion, and show that\nspatial correlations of particle displacements become increasingly long-range\nas the temperature decreases toward the mode coupling critical temperature.",
        "positive": "Reverse Monte Carlo modeling of liquid water with the explicit use of\n  the SPC/E interatomic potential: Reverse Monte Carlo modeling of liquid water, based on one neutron and one\nX-ray diffraction data set, applying also the most popular interatomic\npotential for water, SPC/E, has been performed. The strictly rigid geometry of\nSPC/E water molecules had to be loosened somewhat, in order to be able to\nproduce a good fit to both sets of experimental data. In the final particle\nconfigurations, regularly shaped water molecules and straight hydrogen bonding\nangles were found to be consistent with diffraction results. It has been\ndemonstrated that explicit use of interatomic potentials in RMC has a role to\nplay in future structural modeling of water and aqueous solutions."
    },
    {
        "anchor": "Molecular motions in lipid bilayers studied by the neutron\n  backscattering technique: We report a high energy-resolution neutron backscattering study to\ninvestigate slow motions on nanosecond time scales in highly oriented solid\nsupported phospholipid bilayers of the model system DMPC -d54 (deuterated\n1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine), hydrated with heavy water.\nThis technique allows to discriminate the onset of mobility at different length\nscales for the different molecular components, as e.g.\\@ the lipid acyl-chains\nand the hydration water in between the membrane stacks, respectively, and\nprovides a benchmark test regarding the feasibility of neutron backscattering\ninvestigations on these sample systems. We discuss freezing of the lipid\nacyl-chains, as observed by this technique, and observe a second freezing\ntransition which we attribute to the hydration water.",
        "positive": "Commensurate-incommensurate transition of cold atoms in an optical\n  lattice: An atomic gas subject to a commensurate periodic potential generated by an\noptical lattice undergoes a superfluid--Mott insulator transition. Confining a\nstrongly interacting gas to one dimension generates an instability where an\narbitrary weak potential is sufficient to pin the atoms into the Mott state;\nhere, we derive the corresponding phase diagram. The commensurate pinned state\nmay be detected via its finite excitation gap and the Bragg peaks in the static\nstructure factor."
    },
    {
        "anchor": "Drag force scaling for penetration into granular media: Impact dynamics is measured for spherical and cylindrical projectiles of many\ndifferent densities dropped onto a variety non-cohesive granular media. The\nresults are analyzed in terms of the material-dependent scaling of the inertial\nand frictional drag contributions to the total stopping force. The inertial\ndrag force scales similar to that in fluids, except that it depends on the\ninternal friction coefficient. The frictional drag force scales as the\nsquare-root of the density of granular medium and projectile, and hence cannot\nbe explained by the combination of granular hydrostatic pressure and Coulomb\nfriction law. The combined results provide an explanation for the\npreviously-observed penetration depth scaling.",
        "positive": "Stabilization/destabilization of cell membranes by multivalent ions:\n  Implications for membrane fusion and division: We propose a mechanism for the stabilization/destabilization of cell\nmembranes by multivalent ions with an emphasis on its implications for the\ndivision and fusion of cells. We find that multivalent cations preferentially\nadsorbed onto a membrane dramatically changes the membrane stability. They not\nonly reduce the surface charge density of the membrane but also induce a\nrepulsive barrier to pore growth. While both of these effects lead to enhanced\nmembrane stability against vesiculation and pore growth, the repulsive barrier\narises from correlated fluctuations of the adsorbed cations and favors closure\nof a pore. Finally, the addition of a small amount of multivalent anions can\nreverse the membrane stabilization, providing an effective way to regulate\nmembrane stability."
    },
    {
        "anchor": "Membrane emulsification for the production of suspensions of uniform\n  microcapsules with tunable mechanical properties: A way forward for high throughput fabrication of microcapsules with uniform\nsize and mechanical properties was reported irrespective of the kinetic process\nof shell assembly. Microcapsules were produced using lab-scale emulsification\nequipment with a micro-engineered membrane in the size range 10-100 $\\mu$m. The\nshell of the microcapsules was assembled at the water-oil interface by\ncomplexation of polyelectrolytes or cross-linking of proteins providing two\ndifferent kinetic processes. Elasticity of microcapsules was characterized with\nan automated extensional flow chamber. Process parameters were optimized to\nobtain suspensions with size variations of 15%. Some strategies were developed\nto obtain uniform elastic properties according to the kinetics of shell\nassembly. If kinetics is limited by diffusion, membrane emulsification and\nshell assembly have to be split into two steps. If kinetics is limited by the\nquantity of reactants encapsulated in the droplet, variations of elastic\nproperties result only from size variations.",
        "positive": "Crystal nuclei and structural correlations in two-dimensional colloidal\n  mixtures: experiment versus simulation: We examine binary mixtures of superparamagnetic colloidal particles confined\nto a two-dimensional water-air interface both by real-space experiments and\nMonte-Carlo computer simulations at high coupling strength. In the simulations,\nthe interaction is modelled as a pairwise dipole-dipole repulsion. While the\nratio of magnetic dipole moments is fixed, the interaction strength governed by\nthe external magnetic field and the relative composition is varied. Excellent\nagreement between simulation and experiment is found for the partial pair\ndistribution functions including the fine structure of the neighbour shells at\nhigh coupling. Furthermore local crystal nuclei in the melt are identified by\nbond-orientational order parameters and their contribution to the pair\nstructure is discussed."
    },
    {
        "anchor": "Tap Density Equations of Granular Powders Based on the Rate Process\n  Theory and the Free Volume Concept: Tap density of a granular powder is often linked to the flowability via Carr\nIndex that measures how tight a powder can be packed, under an assumption that\nmore easily packed powders usually flow poorly. Understanding how particles are\npacked is important for revealing why a powder flows better than others. There\nare two types of empirical equations that were proposed to fit the experimental\ndata of packing fractions vs. numbers of taps in literature: The inverse\nlogarithmic and the stretched exponential. Using the rate process theory and\nthe free volume concept, we obtain the tap density equations and they can be\nreducible to the two empirical equations currently widely used in literature.\nOur equations could potentially fit experimental data better with an additional\nadjustable parameter. The tapping amplitude and frequency, the weight of the\ngranular materials, and the environment temperature are grouped into one\nparameter that weighs the pace of packing process. The current results, in\nconjunction with our previous findings, may imply that both dry(granular)and\nwet(colloidal and polymeric) particle systems are governed by the same physical\nmechanisms in term of the role of the free volume and how particles behave (a\nrate controlled process).",
        "positive": "Nonequilibrium Structure of Colloidal Dumbbells under Oscillatory Shear: We investigate the nonequilibrium behavior of dense, plastic-crystalline\nsuspensions of mildly anisotropic colloidal hard dumbbells under the action of\nan oscillatory shear field by employing Brownian dynamics computer simulations.\nIn particular, we extend previous investigations, where we uncovered novel\nnonequilibrium phase transitions, to other aspect ratios and to a larger\nnonequilibrium parameter space, that is, a wider range of strains and shear\nfrequencies. We compare and discuss selected results in the context of novel\nscattering and rheological experiments. Both simulations and experiments\ndemonstrate that the previously found transitions from the plastic crystal\nphase with increasing shear strain also occur at other aspect ratios. We\nexplore the transition behavior in the strain-frequency phase and summarize it\nin a nonequilibrium phase diagram. Additionally, the experimental rheology\nresults hint at a slowing down of the colloidal dynamics with higher aspect\nratio."
    },
    {
        "anchor": "Effects of target anisotropy on harmonic measure and mean first-passage\n  time: In this paper, we investigate the influence of target anisotropy on two\ncharacteristics of diffusion-controlled reactions: harmonic measure density and\nmean first-passage time. First, we compute the volume-averaged harmonic measure\ndensity on prolate and oblate spheroidal targets inside a confining domain in\nthree dimensions. This allows us to quantify the uniformity of this density in\nthe small target limit. Second, we derive an explicit expression of the mean\nfirst-passage time to such targets and analyze the effect of anisotropy. In\nparticular, we illustrate the accuracy of the capacitance approximation for\nsmall targets.",
        "positive": "Complex flow profiles in microscopic active crystals: Active solids emerge from self-actuating components interacting with each\nother to form crystalline patterns. In equilibrium, commensurability underpins\nour understanding of nanoscale friction and particle-level dynamics of\ncrystals. However, these concepts have yet to be imported into the realm of\nactive matter. Here, we develop an experimental platform and a theoretical\ndescription for microscopic clusters composed of active particles confined and\nself-assembled into small crystals. In our experiments, these crystallites form\nupon circular confinement of active rollers, with a magic number of 61 rollers\nper well. Competition between solidity and self propulsion leads to self\nshearing and complex flow inversion behaviour, along with self sliding states\nand activity induced melting. We discover active stick slip dynamics, which\nperiodically switch between a commensurate static state and an incommensurate\nself-sliding state characterised by a train of localised defects. We describe\nthe steady state behaviour using a discretised model of active hydrodynamics.\nWe then quantify the intermittent stick slip dynamics using a self-propelled\nextension of the Frenkel Kontorova (FK) model, a fundamental workhorse of\nslipping and flow in crystals. Our findings in a colloidal model system point\nto a wealth of phenomena in incommensurate active solids as design principles\nfor both assembly and robotics down to the nanoscale."
    },
    {
        "anchor": "Record Dynamics in the Parking Lot Model: We present an analytical and numerical study of the parking lot model (PLM)\nof granular relaxation and make a connection to the aging dynamics of dense\ncolloids. As we argue, the PLM is a Kinetically Constrained Model which\nfeatures astronomically large equilibration times and displays a characteristic\naging behavior on all observable time scales. The density of parked cars\ndisplays quasi-equilibrium Gaussian fluctuations interspersed by increasingly\nrare intermittent events, quakes, which can lead to an increase of the density\nto new record values. Defining active clusters as the shortest domains of\nparked cars which must be re-arranged to allow further insertions, we find that\ntheir typical length grows logarithmically with time for low enough\ntemperatures and show how the number of active clusters on average gradually\ndecreases as the system approaches equilibrium. We further characterize the\naging process in terms of the statistics of the record sized fluctuations in\nthe interstitial free volume which lead to quakes and show that quakes are\nuncorrelated and that they can be approximately described as a Poisson process\nin logarithmic time.",
        "positive": "Molecular and all solid DFT studies of the magnetic and chemical bonding\n  properties within KM[Cr(CN)$_6$] (M = V, Ni) complexes: A study at both the molecular and extended solid level in the framework DFT\nis carried out for KM[Cr(CN)$_6$] (M = V, Ni). From molecular calculations, the\nexchange parameters J are obtained, pointing to the expected magnetic ground\nstates, i.e., antiferromagnetic for M = V with J = -296.5 cm$^{-1}$ and\nferromagnetic for M = Ni with J = +40.5 cm$^{-1}$. From solid state\ncomputations the same ground states and J magnitudes are confirmed from energy\ndifferences. Furthermore an analysis of the site projected density of states\nand of the chemical bonding is developed in which the cyanide ion linkage is\nanalyzed addressing some isomerism aspects."
    },
    {
        "anchor": "Large-N $\u03b2$-function for superconducting films in a magnetic field: By considering the large-N Ginzburg-Landau model, compactified in one of the\nspatial dimensions, we determine the beta-function and find an infrared stable\nfixed point for a superconducting film for dimensions $4<D<6$. We find that\nthis fixed point is independent of the film thickness ($L$). For the physical\ndimension D=3 we conclude that if a transition exists it is not a second order\none.",
        "positive": "Dependence of the glass transition and jamming densities on spatial\n  dimension: We investigate the dynamics of soft sphere liquids through computer\nsimulations for spatial dimensions from $d =3$ to $8$, over a wide range of\ntemperatures and densities. Employing a scaling of density-temperature\ndependent relaxation times, we precisely identify the density $\\phi_0$ which\nmarks the ideal glass transition in the hard sphere limit, and a crossover from\nsub- to super-Arrhenius temperature dependence. The difference between $\\phi_0$\nand the athermal jamming density $\\phi_J$, small in 3 and 4 dimensions,\nincreases with dimension, with $\\phi_0 > \\phi_J$ for $d > 4$. We compare our\nresults with recent theoretical calculations."
    },
    {
        "anchor": "Assessing the Utility of Structure in Amorphous Materials: This paper presents a set of general strategies for the analysis of structure\nin amorphous materials and a general approach to assessing the utility of a\nselected structural description. Measures of structural diversity and utility\nare defined and applied to two model glass forming binary atomic alloys. In\naddition, a new measure of incipient crystal-like organization is introduced,\nsuitable for cases where the stable crystal is a compound structure.",
        "positive": "Self-Propelled Rods: Linking Alignment-Dominated and Repulsion-Dominated\n  Active Matter: We study a robust model of self-propelled rods interacting via volume\nexclusion and show that its collective dynamics encompasses both that of the\ncorresponding Vicsek-style model (where local alignment is the sole\ninteraction), and motility-induced phase separation (which occurs when\nrepulsion is dominant). These results unify these heretofore largely\ndisconnected bodies of knowledge on dry active matter and clarify the nature of\nthe various phases involved."
    },
    {
        "anchor": "Capillary control of collapse in soft composite columns: Euler buckling is the elastic instability of a column subjected to\nlongitudinal compression forces at its ends. The buckling instability occurs\nwhen the compressing load reaches a critical value and an infinitesimal\nfluctuation leads to a large amplitude deflection. Since Euler's original\nstudy, this process has been extensively studied in homogeneous, isotropic,\nlinear-elastic solids. Here, we examine the nature of the buckling in\ninhomogeneous soft composite materials. In particular, we consider a soft host\nwith liquid inclusions both large and small relative to the elastocapillarity\nlength, which lead to softening and stiffening of a homogeneous composite\nrespectively. However, by imposing a gradient of the inclusion volume fraction\nor by varying the inclusion size we can deliberately manipulate the spatial\nstructure of the composite properties of a column and thereby control the\nnature of Euler buckling.",
        "positive": "Knotted Defects in Nematic Liquid Crystals: We show that the number of distinct topological states associated to a given\nknotted defect, $L$, in a nematic liquid crystal is equal to the determinant of\nthe link $L$. We give an interpretation of these states, demonstrate how they\nmay be identified in experiments and describe the consequences for material\nbehaviour and interactions between multiple knots. We show that stable knots\ncan be created in a bulk cholesteric and illustrate the topology by classifying\na simulated Hopf link. In addition we give a topological heuristic for the\nresolution of strand crossings in defect coarsening processes which allows us\nto distinguish topological classes of a given link and to make predictions\nabout defect crossings in nematic liquid crystals."
    },
    {
        "anchor": "Heterogeneous Solvent Dissipation Coupled with Particle Rearrangement in\n  Shear Thinning Non-Brownian Suspensions: Dense non-Brownian suspensions exhibit significant shear thinning, although a\ncomprehensive understanding of the full scope of this phenomenon remains\nelusive. This study numerically reveals intimate heterogenous coupled dynamics\nbetween many-body particle motions and solvent hydrodynamics in shear-thinning\nnon-Brownian suspensions. We demonstrate the spatially correlated viscous\ndissipation and particle motions; they share the same characteristic length,\nwhich decreases with increasing shear rate. We further show that, at lower\nshear rates, significant particle density changes are induced against the\nincompressibility of the solvent, suggesting the cooperative creation and\nannihilation of gaps and flow channels. We discuss that hydrodynamic\ninteractions may substantially restrict particle rearrangements even in highly\ndense suspensions, influencing the quantitative aspects of macroscopic\nrheology.",
        "positive": "Isotropic-nematic interfacial tension of hard and soft rods: application\n  of advanced grand canonical biased sampling techniques: Coexistence between the isotropic and the nematic phase in suspensions of\nrods is studied using grand canonical Monte Carlo simulations with a bias on\nthe nematic order parameter. The biasing scheme makes it possible to estimate\nthe interfacial tension gamma in systems of hard and soft rods. For hard rods\nwith L/D=15, we obtain gamma ~ 1.4 kB T/L^2, with L the rod length, D the rod\ndiameter, T the temperature, and kB the Boltzmann constant. This estimate is in\ngood agreement with theoretical predictions, and the order of magnitude is\nconsistent with experiments."
    },
    {
        "anchor": "Aqueous self-assembly of a wide range of sophorolipid and glucolipid\n  microbial bioamphiphiles (biosurfactants): considerations on the\n  structure-properties relationship: Sophorolipids are well-known scaled-up microbial glycolipid biosurfactants\nwith a strong potential for commercialization due to their biological origin\nand mildness in contact with the skin and the environment compared to classical\nsurfactants. However, their association properties in water are still poorly\nunderstood, they cannot be predicted and their behavior in solution challenges\nhalf a century of knowledge generated in the field of surfactant science. By\nstudying forty different types of sophorolipids and sophorosides in water using\nsmall angle X-ray scattering, and optical and cryogenic transmission electron\nmicroscopy, this work provides better understanding of their structure-property\nrelationship and identifies which chemical groups in their molecular structure\nhave a critical influence on their self-assembly properties. Structural\nfeatures like the number of sugar headgroups, acetylation, end-chain functional\ngroup, (un)saturation, lactonization and length of chain are adjusted to both\nrationalize their impact and understand their effect on self-assembly. The\nnumber of sugar groups, pH, (un)saturation and lactonization were found to have\na critical impact on sophorolipid self-assembly. The chemical nature of the\nend-chain functional group and chain length were also found to have a possibly\ncritical impact, depending on the specific type of chemical function (COOH and\nlong chains are critical). Mono- and diacetylation, as well as the position of\nsophorose in the fatty acid ($\\omega$, $\\omega$-1), are not critical, i.e.,\nthey did not significantly influence sophorolipid self-assembly.",
        "positive": "A scaling law for aeolian dunes on Mars, Venus, Earth, and for\n  subaqueous ripples: The linear stability analysis of the equations governing the evolution of a\nflat sand bed submitted to a turbulent shear flow predicts that the wavelength\n$\\lambda$ at which the bed destabilises to form dunes should scale with the\ndrag length $L_{\\rm drag} = \\frac{\\rho_s}{\\rho_f} d$. This scaling law is\ntested using existing and new measurements performed in water (subaqueous\nripples), in air (aeolian dunes and fresh snow dunes), in a high pressure\nCO$_2$ wind tunnel reproducing conditions close to the Venus atmosphere and in\nthe low pressure CO$_2$ martian atmosphere (martian dunes). A difficulty is to\ndetermine the diameter of saltating grains on Mars. A first estimate comes from\nphotographs of aeolian ripples taken by the rovers Opportunity and Spirit,\nshowing grains whose diameters are smaller than on Earth dunes. In addition we\ncalculate the effect of cohesion and viscosity on the dynamic and static\ntransport thresholds. It confirms that the small grains visualised by the\nrovers should be grains experiencing saltation. Finally, we show that, within\nerror bars, the scaling of $\\lambda$ with $L_{\\rm drag}$ holds over almost five\ndecades. We conclude with a discussion on the time scales and velocities at\nwhich these bed instabilities develop and propagate on Mars."
    },
    {
        "anchor": "4D printing of mechanical metamaterials: Mechanical metamaterials owe their extraordinary properties and\nfunctionalities to their micro-/nanoscale design of which shape, including both\ngeometry and topology, is perhaps the most important aspect. 4D printing\nenables programmed, predictable, and precise change in the shape of mechanical\nmetamaterials to achieve multi-functionality, adaptive properties, and the\nother types of desired behaviors that cannot be achieved using simple 3D\nprinting. This paper presents an overview of 4D printing as applied to\nmechanical metamaterials. It starts by presenting a systematic definition of\nwhat 4D printing is and what shape aspects (e.g., geometry, topology) are\nrelevant for the 4D printing of mechanical metamaterials. Instead of focusing\non different printing processes and materials, the paper addresses the most\nfundamental aspects of the shapeshifting behaviors required for transforming a\nflat construct to a target 3D shape (i.e., 2D to 3D shapeshifting) or\ntransforming a 3D shape to another 3D shape (i.e., 3D to 3D shapeshifting). In\neither case, we will discuss the rigid-body shape morphing (e.g., rigid\norigami) as well as deformable-body shapeshifting. The paper concludes with a\ndiscussion of the major challenges ahead of us for applying 4D printing to\nmechanical metamaterials and suggests several areas for future research.",
        "positive": "The fracture of highly deformable soft materials: A tale of two length\n  scales: The fracture of highly deformable soft materials is of great practical\nimportance in a wide range of technological applications, emerging in fields\nsuch as soft robotics, stretchable electronics and tissue engineering. From a\nbasic physics perspective, the failure of these materials poses fundamental\nchallenges due to the strongly nonlinear and dissipative deformation involved.\nIn this review, we discuss the physics of cracks in soft materials and\nhighlight two length scales that characterize the strongly nonlinear elastic\nand dissipation zones near crack tips in such materials. We discuss physical\nprocesses, theoretical concepts and mathematical results that elucidate the\nnature of the two length scales, and show that the two length scales can\nclassify a wide range of materials. The emerging multi-scale physical picture\noutlines the theoretical ingredients required for the development of predictive\ntheories of the fracture soft materials. We conclude by listing open challenges\nand future investigation directions."
    },
    {
        "anchor": "A blend of stretching and bending in nematic polymer networks: Nematic polymeric networks are (heat and light) activable materials, which\ncombine the features of rubber and nematic liquid crystals. When only the\nstretching energy of a thin sheet of nematic polymeric network is minimized,\nthe intrinsic (Guassian) curvature of the shape it takes upon (thermal or\noptical) actuation is determined. This, unfortunately, produces a multitude of\npossible shapes, for which we need a selection criterion, which may only be\nprovided by a correcting bending energy depending on the extrinsic curvatures\nof the deformed shape. The literature has so far offered approximate\ncorrections depending on the mean curvature. In this paper, we derive the\nappropriate bending energy of a sheet of polymeric nematic network from the\ncelebrated neo-classical energy of nematic elastomers in three space\ndimensions. This task is performed via a dimension reduction based on a\nmodified Kirchhoff-Love hypothesis, which withstands to the criticism of more\nsophisticated analytical tools. The result is a surface elastic free-energy\ndensity where stretching and bending are blended together; they may or may not\nbe length-separated, and should be minimized together. The extrinsic curvatures\nof the deformed shape not only feature in the bending energy through the mean\ncurvature, but also through the relative orientation of the nematic director in\nthe frame of the directions of principal curvature.",
        "positive": "Elastogranularity in Binary Granular Mixtures: Frustration arises for a broad class of physical systems where confinement\n(geometric) or the presence of a perturbation (kinematic) prevents\nequilibration to a minimum energy state. By varying the diameter ratio and\npacking fraction in granular arrays surrounding a slowly elongating elastica,\nwe characterize the resulting elastogranular interactions taking place in a\ntransitional, amorphous medium. For low number density packings prepared with\nmoderate to large bidispersity, we find the critical injected arclength to\nelicit jamming follows the same scaling law observed in monodisperse arrays.\nBeyond the jamming point, the elastica is seen to relax its bending energy\nwithin packings with progressively larger diameter ratios towards the shape\nexpected when deforming within more fluid-like media."
    },
    {
        "anchor": "Do liquid drops roll or slide on inclined surfaces?: We study the motion of a two-dimensional droplet on an inclined surface,\nunder the action of gravity, using a diffuse interface model which allows for\narbitrary equilibrium contact angles. The kinematics of motion is analysed by\ndecomposing the gradient of the velocity inside the droplet into a shear and a\nresidual flow. This decomposition helps in distinguishing sliding versus\nrolling motion of the drop. Our detailed study confirms intuition, in that\nrolling motion dominates as the droplet shape approaches a circle, and the\nviscosity contrast between the droplet and the ambient fluid becomes large. As\na consequence of kinematics, the amount of rotation in a general droplet shape\nfollows a universal curve characterised by geometry, and independent of Bond\nnumber, surface inclination and equilibrium contact angle, but determined by\nthe slip length and viscosity contrast. Our results open the way towards a\nrational design of droplet-surface properties, both when rolling motion is\ndesirable (as in self-cleaning hydrophobic droplets) or when it must be\nprevented (as in insecticide sprays on leaves).",
        "positive": "Active chiral molecules in activity gradients: While the behavior of active colloidal molecules is well studied by now for a\nconstant activity, the effect of activity gradients is much less understood.\nHere we explore one of the simplest molecules in activity gradients, namely\nactive chiral dimers composed of two particles with opposite active torques of\nthe same magnitude. We show analytically that with increasing torque, the dimer\nswitches its behavior from antichemotactic to chemotactic. The origin of the\nemergent chemotaxis is the cooperative exploration of activity gradient by the\ntwo particles. While one of the particles moves into higher activity regions,\nthe other moves towards lower activity region resulting in a net bias in the\ndirection of higher activity. We do a comparative study of chiral active\nparticles with charged Brownian particles under magnetic field and show that\ndespite the fundamental similarity in terms of their odd-diffusive behavior,\ntheir dynamics and chemotactic behavior are generally not equivalent. We\ndemonstrate this explicitly in a dimer composed of oppositely charged active\nparticles, which remains antichemotactic for any magnetic field."
    },
    {
        "anchor": "Modulated wavepackets associated with longitudinal dust grain\n  oscillations in a dusty plasma crystal: The nonlinear amplitude modulation of longitudinal dust lattice waves (LDLWs)\npropagating in a dusty plasma crystal is investigated in a continuum\napproximation. It is shown that long wavelength LDLWs are modulationally\nstable, while shorter wavelengths may be unstable. The possibility for the\nformation and propagation of different envelope localized excitations is\ndiscussed. It is shown that the total grain displacement bears a (weak)\nconstant displacement (zeroth harmonic mode), due to the asymmetric form of the\nnonlinear interaction potential. The existence of asymmetric envelope localized\nmodes is predicted. The types and characteristics of these coherent nonlinear\nstructures are discussed.",
        "positive": "On fusogenicity of positively charged phased-separated lipid vesicles:\n  experiments and computational simulations: This paper studies the fusogenicity of cationic liposomes in relation to\ntheir surface distribution of cationic lipids and utilizes membrane phase\nseparation to control this surface distribution. It is found that concentrating\nthe cationic lipids into small surface patches on liposomes, through\nphase-separation, can enhance liposome's fusogenicity. Further concentrating\nthese lipids into smaller patches on the surface of liposomes led to an\nincreased level of fusogenicity. These experimental findings are supported by\nnumerical simulations using a mathematical model for phase-separated charged\nliposomes. Findings of this study may be used for design and development of\nhighly fusogenic liposomes with minimal level of toxicity."
    },
    {
        "anchor": "The structure of fluid trifluoromethane and methylfluoride: We present hard X-ray and neutron diffraction measurements on the polar\nfluorocarbons HCF3 and H3CF under supercritical conditions and for a range of\nmolecular densities spanning about a factor of ten. The Levesque-Weiss-Reatto\ninversion scheme has been used to deduce the site-site potentials underlying\nthe measured partial pair distribution functions. The orientational\ncorrelations between adjacent fluorocarbon molecules -- which are characterized\nby quite large dipole moments but no tendency to form hydrogen bonds -- are\nsmall compared to a highly polar system like fluid hydrogen chloride. In fact,\nthe orientational correlations in HCF3 and H3CF are found to be nearly as small\nas those of fluid CF4, a fluorocarbon with no dipole moment.",
        "positive": "Polydispersity Effects in Colloid-Polymer Mixtures: We study phase separation and transient gelation in a mixture consisting of\npolydisperse colloids and non-adsorbing polymers, where the ratio of the\naverage size of the polymer to that of the colloid is approximately 0.063.\nUnlike what has been reported previously for mixtures with somewhat lower\ncolloid polydispersity, the addition of polymers does not expand the\nfluid-solid coexistence region. Instead, we find a region of fluid-solid\ncoexistence which has an approximately constant width but an unexpected\nre-entrant shape. We detect the presence of a metastable gas-liquid binodal,\nwhich gives rise to two-stepped crystallization kinetics that can be\nrationalized as the effect of fractionation. Finally, we find that the\nseparation into multiple coexisting solid phases at high colloid volume\nfractions predicted by equilibrium statistical mechanics is kinetically\nsuppressed before the system reaches dynamical arrest."
    },
    {
        "anchor": "Lumped parameter modelling of ferroelectric ceramics for control\n  applications using simulink: Simplifying the constitutive behaviour of a material in terms of the lumped\nparameter elements is useful to design plant models in control engineering. In\nthis contribution, a lumped parameter modelling approach is used to represent\nthe constitutive behaviour of ferroelectric ceramics. Using the elements\navailable in simulink, an electrical circuit is designed to simulate the\nferroelectric behaviour. The simulation results of dielectric and butterfly\nhysteresis shows the possibility of applying the lumped parameter modelling\napproach in the design of displacement control systems.",
        "positive": "Solid-liquid composite structures: elastic beams with embedded\n  liquid-filled parallel-channel networks: Deformation due to embedded fluidic networks is currently studied in the\ncontext of soft-actuators and soft-robotics. Expanding on this concept, beams\ncan be designed so that the pressure in the channel-network is created directly\nfrom external forces acting on the beam, and thus can be viewed as passive\nsolid-liquid composite structure. We obtain a continuous function relating the\nnetwork geometry to the deformation. This enables design of networks creating\narbitrary steady and time varying deformation-fields as well as to eliminate\ndeformation created by external forces."
    },
    {
        "anchor": "Glass Transition Temperature and Dynamics of $\u03b1$-Process in Thin\n  Polymer Films: The glass transition temperature $T_g$ and the temperature $T_{\\alpha}$\ncorresponding to the peak in the dielectric loss due to the $\\alpha$-process\nhave been simultaneously determined as functions of film thickness $d$ through\ndielectric measurements for thin films of polystyrene. A decrease of $T_g$ was\nobserved with decreasing film thickness, while $T_{\\alpha}$ was found to remain\nalmost constant for $d > d_c$ and decrease drastically for $d < d_c$. Here,\n$d_c$ is a critical thickness dependent on molecular weight. The thickness\ndependence of $T_g$ is related to the distribution of relaxation times of the\n$\\alpha$-process, not to the relaxation time itself.",
        "positive": "Pattern formation in a model of photochemical reaction: Stripe and columnar patterns were experimentally found in photopolymer films\nduring irradiation of collimated UV light. We propose a mathematical model of\nphotopolymerization, perform numerical simulation, and find a spatially\nperiodic columnar structure."
    },
    {
        "anchor": "The effects of packing structure on the effective thermal conductivity\n  of granular media: A grain scale investigation: Structural characteristics are considered to be the dominant factors in\ndetermining the effective properties of granular media, particularly in the\nscope of transport phenomena. Towards improved heat management, thermal\ntransport in granular media requires an improved fundamental understanding. In\nthis study, the effects of packing structure on heat transfer in granular media\nare evaluated at macro- and grain-scales. At the grain-scale, a gas-solid\ncoupling heat transfer model is adapted into a discrete-element-method to\nsimulate this transport phenomenon. The numerical framework is validated by\nexperimental data obtained using a plane source technique, and the\nSmoluschowski effect of the gas phase is found to be captured by this\nextension. By considering packings of spherical SiO2 grains with an\ninterstitial helium phase, vibration induced ordering in granular media is\nstudied, using the simulation methods developed here, to investigate how\ndisorder-to-order transitions of packing structure enhance effective thermal\nconductivity. Grain-scale thermal transport is shown to be influenced by the\nlocal neighbourhood configuration of individual grains. The formation of an\nordered packing structure enhances both global and local thermal transport.\nThis study provides a structure approach to explain transport phenomena, which\ncan be applied in properties modification for granular media.",
        "positive": "Attraction and ionic correlations between charged stiff polyelectrolytes: We use Molecular Dynamics simulations to study attractive interactions and\nthe underlying ionic correlations between parallel like-charged rods in the\nabsence of additional salt. For a generic bulk system of rods we identify a\nreduction of short range repulsions as the origin of a negative osmotic\ncoefficient. The counterions show signs of a weak three-dimensional order in\nthe attractive regime only once the rod-imposed charge-inhomogeneities are\ndivided out. We also treat the case of attraction between a single pair of rods\nfor a few selected line charge densities and rod radii. Measurements of the\nindividual contributions to the force between close rods are studied as a\nfunction of Bjerrum length. We find that even though the total force is always\nattractive at sufficiently high Bjerrum length, the electrostatic contribution\ncan ultimately become repulsive. We also measure azimuthal and longitudinal\ncorrelation functions to answer the question how condensed ions are distributed\nwith respect to each other and to the neighboring rod. For instance, we show\nthat the prevalent image of mutually interlocked ions is qualitatively correct,\neven though modifications due to thermal fluctuations are usually strong."
    },
    {
        "anchor": "Flexibility defines structure in crystals of amphiphilic DNA nanostars: DNA nanostructures with programmable shape and interactions can be used as\nbuilding blocks for the self-assembly of crystalline materials with prescribed\nnanoscale features, holding a vast technological potential. Structural rigidity\nand bond directionality have been recognised as key design features for DNA\nmotifs to sustain long-range order in 3D, but the practical challenges\nassociated with prescribing building-block geometry with sufficient accuracy\nhave limited the variety of available designs. We have recently introduced a\nnovel platform for the one-pot preparation of crystalline DNA frameworks\nsupported by a combination of Watson-Crick base pairing and hydrophobic forces\n[Nano Lett., 17(5):3276-3281, 2017]. Here we use small angle X-ray scattering\nand coarse-grained molecular simulations to demonstrate that, as opposed to\navailable all- DNA approaches, amphiphilic motifs do not rely on structural\nrigidity to support long-range order. Instead, the flexibility of amphiphilic\nDNA building-blocks is a crucial feature for successful crystallisation.",
        "positive": "Higher derivative free energy terms and interfacial curvatures: High derivative terms do not play a major role in field theories because of\nthe associated complexity and inherent difficulty in connecting these terms to\nphysically measurable quantities. A role for higher derivative terms is\nanalyzed for the case of field theories used to describe phase separated\nsystems. In these theories, higher derivative terms are directly connected to\nan interfacial free energy which contains the mean and the Gaussian curvature\nand are shown to determine explicitly the shape of the interface."
    },
    {
        "anchor": "Coarse-Grained Methods for Heterogeneous Vesicles with Phase-Separated\n  Domains: Elastic Mechanics of Shape Fluctuations, Plate Compression, and\n  Channel Insertion: We develop coarse-grained particle approaches for studying the elastic\nmechanics of vesicles with heterogeneous membranes having phase-separated\ndomains. We perform simulations both of passive shape fluctuations and of\nactive systems where vesicles are subjected to compression between two plates\nor subjected to insertion into narrow channels. Analysis methods are developed\nfor mapping particle configurations to continuum fields with spherical\nharmonics representations. Heterogeneous vesicles are found to exhibit rich\nbehaviors where the heterogeneity can amplify surface two-point correlations,\nreduce resistance during compression, and augment vesicle transport times in\nchannels. The developed methods provide general approaches for characterizing\nthe mechanics of coarse-grained heterogeneous systems taking into account the\nroles of thermal fluctuations, geometry, and phase separation.",
        "positive": "Isomorphs in model molecular liquids: Isomorphs are curves in the phase diagram along which a number of static and\ndynamic quantities are invariant in reduced units. A liquid has good isomorphs\nif and only if it is strongly correlating, i.e., the equilibrium\nvirial/potential energy fluctuations are more than 90% correlated in the NVT\nensemble. This paper generalizes isomorphs to liquids composed of rigid\nmolecules and study the isomorphs of two systems of small rigid molecules, the\nasymmetric dumbbell model and the Lewis-Wahnstrom OTP model. In particular, for\nboth systems we find that the isochoric heat capacity, the excess entropy, the\nreduced molecular center-of-mass self part of the intermediate scattering\nfunction, the reduced molecular center-of-mass radial distribution function to\na good approximation are invariant along an isomorph. In agreement with theory,\nwe also find that an instantaneous change of temperature and density from an\nequilibrated state point to another isomorphic state point leads to no\nrelaxation. The isomorphs of the Lewis-Wahnstrom OTP model were found to be\nmore approximative than those of the asymmetric dumbbell model, which is\nconsistent with the OTP model being less strongly correlating. For both models\nwe find \"master isomorphs\", i.e., isomorphs have identical shape in the\nvirial/potential energy phase diagram."
    },
    {
        "anchor": "Activity-induced instabilities of brain organoids: We present an analytical and numerical investigation of the activity-induced\nhydrodynamic instabilities in model brain organoids. While several mechanisms\nhave been introduced to explain the experimental observation of surface\ninstabilities in brain organoids, the role of activity has been largely\noverlooked. Our results show that the active stress generated by the cells can\nbe a, previously overlooked, contributor to the emergence of surface\ndeformations in brain organoids.",
        "positive": "Symmetry-restoring crossover from defect-free to defect-laden turbulence\n  in polar active matter: Coherent flows of self-propelled particles are characterized by vortices and\njets that sustain chaotic flows, referred to as active turbulence. Here, we\nreveal a crossover between defect-free active turbulence and active turbulence\nladen with topological defects. Interestingly, we show that concurrent to the\ncrossover from defect-free to defect-laden active turbulence is the restoration\nof the previously broken $\\SO(2)$-symmetry signaled by the fast decay of the\ntwo-point correlations. By stability analyses of the topological charge density\nfield, we provide theoretical insights on the criterion for the crossover to\nthe defect-laden active turbulent state. Despite the distinct symmetry features\nbetween these two active turbulence regimes, the flow fluctuations exhibit\nuniversal statistical scaling behaviors at large scales, while the spectrum of\npolarity fluctuations decays exponentially at small length scales compared to\nthe active energy injection length. These findings reveal a new dynamical\ncrossover between distinct spatiotemporal organization patterns in polar active\nmater."
    },
    {
        "anchor": "Mechanics of bioinspired fiber reinforced elastomers: Fiber reinforcement is a crucial attribute of soft bodied muscular hydrostats\nthat have the ability to undergo large deformations and maintain their posture.\nHelically wound fibers around the cylindrical worm body help control the tube\ndiameter and length. Geometric considerations show that a fiber winding angle\nof 54.7 degrees, called the magic angle, results in a maximum enclosed volume.\nFew studies have explored the effects of differential fiber winding on the\nlarge deformation mechanics of fiber reinforced elastomers (FRE). We fabricated\nFRE materials in transversely isotropic layouts varying from 0-90 degrees using\na custom filament winding technique and characterized the nonlinear\nstress-strain relationships using uniaxial and equibiaxial experiments. We used\nthese data within a continuum mechanical framework to propose a novel\nconstitutive model for incompressible FRE materials with embedded extensible\nfibers. The model includes individual contributions from the matrix and fibers\nin addition to coupled terms in strain invariants, I1 and I4. The deviatoric\nstress components show inversion at fiber orientation angles near the magic\nangle in the FRE composites. These results are useful in soft robotic\napplications and in the biomechanics of fiber reinforced tissues such as the\nmyocardium, arteries and skin.",
        "positive": "Designing superselectivity in linker-mediated multivalent nanoparticle\n  adsorption: Using a statistical mechanical model and numerical simulations, we provide\nthe design principle for the bridging strength ($\\xi$) and linker density\n($\\rho$) dependent superselectivity in linker-mediated multivalent nanoparticle\nadsorption. When the bridges are insufficient, the formation of multiple\nbridges leads to both $\\xi$- and $\\rho$-dependent superselectivity. Whereas,\nwhen the bridges are excessive, the system becomes insensitive to bridging\nstrength due to entropy-induced self-saturation and shows a superselective\ndesorption with respect to the linker density. Counterintuitively, lower linker\ndensity or stronger bridging strength enhances the superselectivity. These\nfindings enhance understanding of relevant biological processes and open up\nopportunities for applications in biosensing, drug delivery, and programmable\nself-assembly."
    },
    {
        "anchor": "Ionically charged topological defects in nematic fluids: Charge profiles in liquid electrolytes are of crucial importance for\napplications, such as supercapacitors, fuel cells, batteries, or the\nself-assembly of particles in colloidal or biological settings. However,\ncreating localised (screened) charge profiles in the bulk of such electrolytes,\ngenerally requires the presence of surfaces -- for example, provided by\ncolloidal particles or outer surfaces of the material -- which poses a\nfundamental constraint on the material design. Here, we show that topological\ndefects in nematic electrolytes can perform as regions for local charge\nseparation, forming charged defect cores and in some geometries even electric\nmultilayers, as opposed to the electric double layers found in isotropic\nelectrolytes. Using a Landau-de Gennes-Poisson-Boltzmann theoretical framework,\nwe show that ions highly effectively couple with the topological defect cores\nvia ion solvability, and with the local director-field distortions of the\ndefects via flexoelectricity. The defect charging is shown for different defect\ntypes -- lines, points, and walls -- using geometries of ionically screened\nflat isotropic-nematic interfaces, radial hedgehog point defects and\nhalf-integer wedge disclinations in the bulk and as stabilised by (charged)\ncolloidal particles. More generally, our findings are relevant for possible\napplications where topological defects act as diffuse ionic capacitors or as\nionic charge carriers.",
        "positive": "Soft self-assembly of Weyl materials for light and sound: Soft materials can self-assemble into highly structured phases which\nreplicate at the mesoscopic scale the symmetry of atomic crystals. As such,\nthey offer an unparalleled platform to design mesostructured materials for\nlight and sound. Here, we present a bottom-up approach based on self-assembly\nto engineer three-dimensional photonic and phononic crystals with topologically\nprotected Weyl points. In addition to angular and frequency selectivity of\ntheir bulk optical response, Weyl materials are endowed with topological\nsurface states, which allows for the existence of one-way channels even in the\npresence of time-reversal invariance. Using a combination of group-theoretical\nmethods and numerical simulations, we identify the general symmetry constraints\nthat a self-assembled structure has to satisfy in order to host Weyl points,\nand describe how to achieve such constraints using a symmetry-driven pipeline\nfor self-assembled material design and discovery. We illustrate our general\napproach using block copolymer self-assembly as a model system."
    },
    {
        "anchor": "Dynamic Entropy as a Measure of Caging and Persistent Particle Motion in\n  Supercooled Liquids: The length-scale dependence of the dynamic entropy is studied in a molecular\ndynamics simulation of a binary Lennard-Jones liquid above the mode-coupling\ncritical temperature $T_c$. A number of methods exist for estimating the\nentropy of dynamical systems and we utilize an approximation based on\ncalculating the mean first-passage time (MFPT) for particle displacement\nbecause of its tractability and its accessibility in real and simulation\nmeasurements. The MFPT dynamic entropy $S(\\epsilon)$ is defined to equal the\ninverse of the average first-passage time for a particle to exit a sphere of\nradius $\\epsilon$. This measure of the degree of chaotic motion allows us to\nidentify characteristic time and space scales and to quantify the increasingly\ncorrelated particle motion and intermittency occurring in supercooled liquids.\nIn particular, we identify a ``cage'' size defining the scale at which the\nparticles are transiently localized, and we observe persistent particle motion\nat intermediate length scales beyond the scale where caging occurs.\nFurthermore, we find that the dynamic entropy at the scale of one interparticle\nspacing extrapolates to zero as the mode-coupling temperature $T_c$ is\napproached.",
        "positive": "Time-reversibility during the aging of materials: Physical aging is the generic term for irreversible processes in glassy\nmaterials resulting from molecular rearrangements. We present multi-speckle\ndynamic light-scattering data on an aging sample of the molecular glass former\n1-phenyl-1-propanol following temperature jumps close to the glass transition,\nstarting from and ending in thermal equilibrium. It is demonstrated that the\nmaterial time of the Tool-Narayanaswamy aging formalism can be determined from\nthe time-autocorrelation function of the scattered-light intensity\nfluctuations. These fluctuations are shown to be stationary and reversible when\nregarded as a function of the material time. The glass-forming colloidal\nsynthetic clay Laponite, as well as a chemically aging curing epoxy, are shown\nalso to have material-time-reversible scattered-light intensity fluctuations.\nOur findings, besides showing direct measurements of the material time,\nidentify a fundamental property of aging in quite different contexts, which\npresents a challenge to the current theories of aging."
    },
    {
        "anchor": "Stationary broken parity states in active matter models: We demonstrate that several nonvariational continuum models commonly used to\ndescribe active matter as well as other active systems exhibit nongeneric\nbehavior: each model supports asymmetric but stationary localized states even\nin the absence of pinning at heterogeneities. Moreover, such states only begin\nto drift following a drift-transcritical bifurcation as the activity increases.\nAsymmetric stationary states should only exist in variational systems, i.e., in\nmodels with gradient structure. In other words, such states are expected in\npassive systems, but not in active systems where the gradient structure of the\nmodel is broken by activity. We identify a \"spurious\" gradient dynamics\nstructure of these models that is responsible for this nongeneric behavior, and\ndetermine the types of additional terms that render the models generic, i.e.,\nwith asymmetric states that appear via drift-pitchfork bifurcations and are\ngenerically moving. We provide detailed illustrations of our results using\nnumerical continuation of resting and steadily drifting states in both generic\nand nongeneric cases.",
        "positive": "Intermittent Granular Flow and Clogging with Internal Avalanches: The dynamics of intermittent granular flow through an orifice in a granular\nbin and the associated clogging due to formation of arches blocking the outlet,\nis studied numerically in two-dimensions. Our numerical results indicate that\nfor small hole sizes, the system self-organizes to a steady state and the\ndistribution of the grain displacements decays as power laws. On the other\nhand, for large holes, the outflow distributions are also observed to follow\npower law distributions."
    },
    {
        "anchor": "Stress-activated Constraints in Dense Suspension Rheology: Dispersing small particles in a liquid can produce surprising behaviors when\nthe solids fraction becomes large: rapid shearing drives these systems out of\nequilibrium and can lead to dramatic increases in viscosity (shear-thickening)\nor even solidification (shear jamming). These phenomena occur above a\ncharacteristic onset stress when particles are forced into frictional contact.\nHere we show via simulations how this can be understood within a framework that\nabstracts details of the forces acting at particle-particle contacts into\ngeneral stress-activated constraints on relative particle movement. We find\nthat focusing on just two constraints, affecting sliding and rolling at\ncontact, can reproduce the experimentally observed shear thickening behavior\nquantitatively, despite widely different particle properties, surface\nchemistries, and suspending fluids. Within this framework parameters such as\ncoefficients of sliding and rolling friction can each be viewed as a proxy for\none or more forces of different physical or chemical origin, while the\nparameter magnitudes indicate the relative importance of the associated\nconstraint. In this way, a new link is established that connects features\nobservable in macroscale rheological measurements to classes of constraints\narising from micro- or nano-scale properties.",
        "positive": "The Mullins effect in the wrinkling behavior of highly stretched thin\n  films: Recent work demonstrates that finite-deformation nonlinear elasticity is\nessential in the accurate modeling of wrinkling in highly stretched thin films.\nGeometrically exact models predict an isola-center bifurcation, indicating that\nfor a bounded interval of aspect ratios only, stable wrinkles appear and then\ndisappear as the macroscopic strain is increased. This phenomenon has been\nverified in experiments. In addition, recent experiments revealed the following\nstriking phenomenon: For certain aspect ratios for which no wrinkling occurred\nupon the first loading, wrinkles appeared during the first unloading and again\nduring all subsequent cyclic loading. Our goal here is to present a simple\npseudo-elastic model, capturing the stress softening and residual strain\nobserved in the experiments, that accurately predicts wrinkling behavior on the\nfirst loading that differs from that under subsequent cyclic loading. In\nparticular for specific aspect ratios, the model correctly predicts the\nscenario of no wrinkling during first loading with wrinkling occurring during\nunloading and for all subsequent cyclic loading."
    },
    {
        "anchor": "Dynamic Theory of Polydomain Liquid-Crystal Elastomers: When liquid-crystal elastomers are prepared without any alignment, disordered\npolydomain structures emerge as the materials are cooled into the nematic\nphase. These polydomain structures have been attributed to quenched disorder in\nthe cross-linked polymer network. As an alternative explanation, we develop a\ntheory for the dynamics of the isotropic-nematic transition in liquid-crystal\nelastomers, and show that the dynamics can induce a polydomain structure with a\ncharacteristic length scale, through a mechanism analogous to the Cahn-Hilliard\nequation for phase separation.",
        "positive": "Crystalline Assemblies and Densest Packings of a Family of Truncated\n  Tetrahedra and the Role of Directional Entropic Forces: Polyhedra and their arrangements have intrigued humankind since the ancient\nGreeks and are today important motifs in condensed matter, with application to\nmany classes of liquids and solids. Yet, little is known about the\nthermodynamically stable phases of polyhedrally-shaped building blocks, such as\nfaceted nanoparticles and colloids. Although hard particles are known to\norganize due to entropy alone, and some unusual phases are reported in the\nliterature, the role of entropic forces in connection with polyhedral shape is\nnot well understood. Here, we study thermodynamic self-assembly of a family of\ntruncated tetrahedra and report several atomic crystal isostructures, including\ndiamond, {\\beta}-tin, and high- pressure lithium, as the polyhedron shape\nvaries from tetrahedral to octahedral. We compare our findings with the densest\npackings of the truncated tetrahedron family obtained by numerical compression\nand report a new space filling polyhedron, which has been overlooked in\nprevious searches. Interestingly, the self-assembled structures differ from the\ndensest packings. We show that the self-assembled crystal structures can be\nunderstood as a tendency for polyhedra to maximize face-to-face alignment,\nwhich can be generalized as directional entropic forces."
    },
    {
        "anchor": "Universal Hyperuniform Organization of Cellular Structures in Leaf Vein\n  Networks: Leaf vein network is a hierarchical vascular system that transports water and\nnutrients to the leaf cells. The thick primary veins form a branched network,\nwhile the secondary veins develop closed circuits forming a well-defined\ncellular structure. Through extensive analysis of a variety of distinct leaf\nspecies, we discover that the apparently disordered cellular structures of the\nsecondary vein networks exhibit a universal hyperuniform organization and\npossess a hidden order on large scales. Disorder hyperuniform (DHU) systems\nlack conventional long-range order, yet they completely suppress normalized\nlarge-scale density fluctuations like crystals. Specifically, we find that the\ndistributions of the geometric centers associated with the vein network loops\npossess a vanishing static structure factor in the zero-wavenumber limit, i.e.,\n$S(k) \\sim k^{\\alpha}$, where $\\alpha \\approx 0.64$, providing an example of\nclass III hyperuniformity in biology. This hyperuniform organization leads to\nsuperior efficiency of diffusive transport, as evidenced by the much faster\nconvergence of the time-dependent spreadability $\\mathcal{S}(t)$ to its\nlong-time asymptotic limit, compared to that of other uncorrelated or\ncorrelated disordered but non-hyperuniform organizations. Our results also have\nimplications for the discovery and design of novel disordered network materials\nwith optimal transport properties.",
        "positive": "Strategies for the evolution of sex: We find that the hypothesis made by Jan, Stauffer and Moseley [Theory in\nBiosc., 119, 166 (2000)] for the evolution of sex, namely a strategy devised to\nescape extinction due to too many deleterious mutations, is sufficient but not\nnecessary for the successful evolution of a steady state population of sexual\nindividuals within a finite population. Simply allowing for a finite\nprobability for conversion to sex in each generation also gives rise to a\nstable sexual population, in the presence of an upper limit on the number of\ndeleterious mutations per individual. For large values of this probability, we\nfind a phase transition to an intermittent, multi-stable regime. On the other\nhand, in the limit of extremely slow drive, another transition takes place to a\ndifferent steady state distribution, with fewer deleterious mutations within\nthe asexual population."
    },
    {
        "anchor": "Depletion potential in hard-sphere mixtures: theory and applications: We present a versatile density functional approach (DFT) for calculating the\ndepletion potential in general fluid mixtures. In contrast to brute force DFT,\nour approach requires only the equilibrium density profile of the small\nparticles {\\em before} the big (test) particle is inserted. For a big particle\nnear a planar wall or a cylinder or another fixed big particle the relevant\ndensity profiles are functions of a single variable, which avoids the numerical\ncomplications inherent in brute force DFT. We implement our approach for\nadditive hard-sphere mixtures. By investigating the depletion potential for\nhigh size asymmetries we assess the regime of validity of the well-known\nDerjaguin approximation for hard-sphere mixtures and argue that this fails. We\nprovide an accurate parametrization of the depletion potential in hard-sphere\nfluids which should be useful for effective Hamiltonian studies of phase\nbehavior and colloid structure.",
        "positive": "Force balance of particles trapped at fluid interfaces: We study the effective forces acting between colloidal particles trapped at a\nfluid interface which itself is exposed to a pressure field. To this end we\napply what we call the ``force approach'', which relies solely on the condition\nof mechanical equilibrium and turns to be in a certain sense less restrictive\nthan the more frequently used ``energy approach'', which is based on the\nminimization of a free energy functional. The main goal is to elucidate the\nadvantages and disadvantages of the force approach as compared to the energy\napproach. First, we derive a general stress-tensor formulation of the forces at\nthe interface and work out a useful analogy with 2D electrostatics in the\nparticular case of small deformations of the interface relative to its flat\nconfiguration. We apply this analogy to compute the asymptotic decay of the\neffective force between particles trapped at a fluid interface, extending the\nvalidity of previous results. Second, we address the case of deformations of a\nnon-flat interface. We compute the deformation of a spherical droplet due to\nthe electric field of a charged particle trapped at its surface and conclude\nthat the interparticle capillary force is unlikely to explain certain recent\nexperimental observations. Finally we discuss the application to a generally\ncurved interface and show as an illustrative example that a nonspherical\nparticle deposited on an interface forming a minimal surface is pulled to\nregions of larger curvature."
    },
    {
        "anchor": "Pattern formation of dipolar colloids in rotating fields: Layering and\n  synchronization: We report Brownian dynamics (BD) simulation and theoretical results for a\nsystem of spherical colloidal particles with permanent dipole moments in a\nrotating magnetic field. Performing simulations at a fixed packing fraction and\ndipole coupling parameter, we construct a full non-equilibrium phase diagram as\nfunction of the driving frequency ($\\omega_0$) and field strength ($B_0$). This\ndiagram contains both synchronized states, where the individual particles\nfollow the field with (on average) constant phase difference, and asynchronous\nstates. The synchronization is accompanied by layer formation, i.e. by spatial\nsymmetry-breaking, similar to systems of induced dipoles in rotating fields. In\nthe permanent-dipole case, however, too large $\\omega_0$ yield a breakdown of\nlayering, supplemented by complex changes of the single-particle rotational\ndynamics from synchronous to asynchronous behavior. We show that the limit\nfrequencies $\\omega_c$ can be well described as a bifurcation in the nonlinear\nequation of motion of a single particle rotating in a viscous medium. Finally,\nwe present a simple density functional theory, which describes the emergence of\nlayers in perfectly synchronized states as an equilibrium phase transition.",
        "positive": "Swarming of micron-sized hematite cubes in a rotating magnetic field --\n  Experiments: Energy input by under-field rotation of particles drives the systems to\nemergent non-equilibrium states. Here we investigate the suspension of rotating\nmagnetic cubes. Micron-sized hematite cubes are synthesized and observed\nmicroscopically. When exposed to a rotating magnetic field, they form rotating\nswarms that interact with each other like liquid droplets. We describe the\nswarming behaviour and its limits and characterize swarm size and angular\nvelocity dependence on magnetic field strength and frequency. A quantitative\nagreement with a theoretical model is found for the angular velocity of swarms\nas a function of field frequency. It is interesting to note that hematite\nparticles with peanut or ellipsoidal shapes do not form swarms."
    },
    {
        "anchor": "Combining tomographic imaging and DEM simulations to investigate the\n  structure of experimental sphere packings: We combine advanced image reconstruction techniques from computed X-ray micro\ntomography (XCT) with state-of-the-art discrete element method simulations\n(DEM) to study granular materials. This \"virtual-laboratory\" platform allows us\nto access quantities, such as frictional forces, which would be otherwise\nexperimentally immeasurable.",
        "positive": "Noise activated dissociation of soft elastic contacts: Adhesive forces are capable of deforming a soft elastic object when it comes\nin contact with a flat rigid substrate. The contact is in stable equilibrium if\nthe total energy of the system arising from the elastic and surface forces\nexhibits a minimum at a zero or at a slightly negative load. However, as the\nsystem is continually unloaded, the energy barrier decreases and it eventually\ndisappears, thus leading to a ballistic separation of the contact. While this\ntype of contact splitting has received wide recognition, what has not been much\nappreciated with these types of soft adhesion problems is that rupture of a\ncontact can also occur at any finite sub critical load in the presence of a\nnoise. The soft contact problems are unique in that the noise can be a-thermal,\nwhereas the metastable and stable states of the thermodynamic potential can\narise from the competition of the elastic and the inter-facial energies of the\nsystem. Analysis based on activated rate theory and simulations based on\nstochastic dynamics show that the contact rupture dynamics is amenable to a\nforce and noise induced escape of a particle from a potential well that is\ngeneric to various types of colloidal and macromolecular processes. These ideas\nare useful in understanding the results of a recent experiment involving the\nnoise activated rolling dynamics of a rigid sphere on a surface, where it is\npinned by soft micro-fibrils."
    },
    {
        "anchor": "Microscopic implications of S-DNA: Recent experiments [J. van Mameren et al. PNAS 106, 18231 (2009)] provide a\ndetailed spatial picture of overstretched DNA, showing that under certain\nconditions the two strands of the double helix separate at about 65 pN. It was\nproposed that this observation rules out the existence of an elongated,\nhybridized form of DNA ('S-DNA'). Here we argue that the S-DNA picture is\nconsistent with the observation of unpeeling during overstretching. We\ndemonstrate that assuming the existence of S-DNA does not imply DNA\noverstretching to consist of the complete or near-complete conversion of the\nmolecule from B- to S-form. Instead, this assumption implies in general a more\ncomplex dynamic coexistence of hybridized and unhybridized forms of DNA. We\nargue that such coexistence can rationalize several recent experimental\nobservations.",
        "positive": "Contact mechanics of and Reynolds flow through saddle points: On the\n  coalescence of contact patches and the leakage rate through near-critical\n  constrictions: We study numerically local models for the mechanical contact between two\nsolids with rough surfaces. When the solids softly touch either through\nadhesion or by a small normal load $L$, contact only forms at isolated patches\nand fluids can pass through the interface. When the load surpasses a threshold\nvalue, $L_c$, adjacent patches coalesce at a critical constriction, i.e., near\npoints where the interfacial separation between the undeformed surfaces forms a\nsaddle point. This process is continuous without adhesion and the interfacial\nseparation near percolation is fully defined by scaling factors and the sign of\n$L_c-L$. The scaling factors lead to a Reynolds flow resistance which diverges\nas $(L_c-L)^\\beta$ with $\\beta = 3.45$. Contact merging and destruction near\nsaddle points becomes discontinuous when either short-range adhesion or\nspecific short-range repulsion are added to the hard-wall repulsion. These\nresults imply that coalescence and break-up of contact patches can contribute\nto Coulomb friction and contact aging."
    },
    {
        "anchor": "Heirarchical and synergistic self-assembly in composites of model\n  Wormlike micellar-polymers and nanoparticles results in nanostructures with\n  diverse morphologies: Using Monte Carlo simulations, we investigate the self-assembly of model\nnanoparticles inside a matrix of model equilibrium polymers (or matrix of\nWormlike micelles) as a function of the polymeric matrix density and the\nexcluded volume parameter between polymers and nanoparticles. In this paper, we\nshow morphological transitions in the system architecture via synergistic\nself-assembly of nanoparticles and the equilibrium polymers. In a synergistic\nself-assembly, the resulting morphology of the system is a result of the\ninteraction between both nanoparticles and the polymers, unlike the polymer\ntemplating method. We report the morphological transition of nanoparticle\naggregates from percolating network-like structures to non-percolating clusters\nas a result of the change in the excluded volume parameter between\nnanoparticles and polymeric chains. In parallel with the change in the\nself-assembled structures of nanoparticles, the matrix of equilibrium polymers\nalso shows a transition from a dispersed state to a percolating network-like\nstructure formed by the clusters of polymeric chains. We show that the shape\nanisotropy of the nanoparticle clusters formed is governed by the polymeric\ndensity resulting in rod-like, sheet-like or other anisotropic nanoclusters. It\nis also shown that the pore shape and the pore size of the porous network of\nnanoparticles can be changed by changing the minimum approaching distance\nbetween nanoparticles and polymers. We provide a theoretical understanding of\nwhy various nanostructures with very different morphologies are obtained.",
        "positive": "Anharmonic properties of vibrational excitations in amorphous solids: Understanding the vibrational and thermal properties of amorphous solids is\none of the most discussed and long-standing issues in condensed matter physics.\nRecent works have made significant steps towards understanding harmonic\nvibrational states. In particular, it has been established that quasi-localized\nvibrational modes emerge in addition to phonon-like vibrational modes. In this\nwork, we study the anharmonic properties of these vibrational modes. We find\nthat vibrational modes exhibit anharmonicities that induce particle\nrearrangements and cause transitions to different states. These anharmonicities\nare distinct from those in crystals, where particle rearrangements never occur.\nRemarkably, for both the phonon modes and quasi-localized modes, the\nvibrational modes exhibit strong anharmonicities, and the induced particle\nrearrangements are always localized in space and are composed of 1 to 1000\nparticles. Our findings contribute to the understanding of low-temperature\nthermal properties, for which anharmonic vibrations are crucial."
    },
    {
        "anchor": "Loading a Bose-Einstein Condensate onto an Optical Lattice: an\n  Application of Optimal Control Theory to The Non Linear Schr\u00f6dinger\n  Equation: Using a set of general methods developed by Krotov [A. I. Konnov and V. A.\nKrotov, Automation and Remote Control, {\\bf 60}, 1427 (1999)], we extend the\ncapabilities of Optimal Control Theory to the Nonlinear Schr\\\"odinger Equation\n(NLSE). The paper begins with a general review of the Krotov approach to\noptimization. Although the linearized version of the method is sufficient for\nthe linear Schr\\\"odinger equation, the full flexibility of the general method\nis required for treatment of the nonlinear Schr\\\"odinger equation. Formal\nequations for the optimization of the NLSE, as well as a concrete algorithm are\npresented. As an illustration, we consider a Bose-Einstein condensate initially\nat rest in a harmonic trap. A phase develops across the BEC when an optical\nlattice potential is turned on. The goal is to counter this effect and keep the\nphase flat by adjusting the trap strength. The problem is formulated in the\nlanguage of Optimal Control Theory (OCT) and solved using the above\nmethodology. To our knowledge, this is the first rigorous application of OCT to\nthe Nonlinear Schr\\\"odinger equation, a capability that is bound to have\nnumerous other applications.",
        "positive": "Coupling/decoupling between translational and rotational dynamics in a\n  supercooled molecular liquid: We use molecular dynamics computer simulations to investigate the\ncoupling/decoupling between translational and rotational dynamics in a\nglass-forming liquid of dumbbells. This is done via a careful analysis of the\n$\\alpha$-relaxation time $\\tau_{q^{*}}^{\\rm C}$ of the incoherent\ncenter-of-mass density correlator at the structure factor peak, the\n$\\alpha$-relaxation time $\\tau_{2}$ of the reorientational correlator, and the\ntranslational ($D_{t}$) and rotational ($D_{r}$) diffusion constants. We find\nthat the coupling between the relaxation times $\\tau_{q^{*}}^{\\rm C}$ and\n$\\tau_{2}$ increases with decreasing temperature $T$, whereas the coupling\ndecreases between the diffusivities $D_{t}$ and $D_{r}$. In addition, the\n$T$-dependence of $D_{t}$ decouples from that of $1/\\tau_{2}$, which is\nconsistent with previous experiments and has been interpreted as a signature of\nthe \"translation-rotation decoupling.\" We trace back these apparently\ncontradicting observations to the dynamical heterogeneities in the system. We\nshow that the decreasing coupling in the diffusivities $D_{t}$ and $D_{r}$ is\nonly apparent due to the inadequacy of the concept of the rotational diffusion\nconstant for describing the reorientational dynamics in the supercooled state.\nWe also argue that the coupling between $\\tau_{q^{*}}^{\\rm C}$ and $\\tau_{2}$\nand the decoupling between $D_{t}$ and $1/\\tau_{2}$, both of which strengthen\nupon cooling, can be consistently understood in terms of the growing dynamic\nlength scale."
    },
    {
        "anchor": "Correlated diffusion of colloidal particles near a liquid-liquid\n  interface: Optical microscopy and multi-particle tracking are used to investigate the\ncross-correlated diffusion of quasi two-dimensional (2D) colloidal particles\nnear an oil-water interface. It is shown that the effect of the interface on\ncorrelated diffusion is asymmetric. Along the line joining the centers of\nparticles, the amplitude of correlated diffusion coefficient ${D}_{\\|}(r)$ is\nenhanced by the interface, while the decay rate of ${D}_{\\|}(r)$ is hardly\naffected. At the direction perpendicular to the line, the decay rate of\n${D}_{\\bot}(r)$ is enhanced at short inter-particle separation $r$. This\nenhancing effect fades at the long $r$. In addition, both $D_{\\|}(r)$ and\n$D_{\\bot}(r)$ are independent of the colloidal area fraction $n$ at long $r$,\nwhich indicates that the hydrodynamic interactions (HIs) among the particles\nare dominated by that through the surrounding fluid at this region. However, at\nshort $r$, $D_{\\bot}(r)$ is dependent on $n$, which suggests the HIs are more\ncontributed from the 2D particle monolayer self.",
        "positive": "Thermal Schwinger Effect: Defect Production in Compressed Filament\n  Bundles: We discuss the response of biopolymer filament bundles bound by transient\ncross linkers to compressive loading. These systems admit a mechanical\ninstability at stresses typically below that of traditional Euler buckling. In\nthis instability, there is thermally-activated pair production of topological\ndefects that generate localized regions of bending -- kinks. These kinks\nshorten the bundle's effective length thereby reducing the elastic energy of\nthe mechanically loaded structure. This effect is the thermal analog of the\nSchwinger effect, in which a sufficiently large electric field causes\nelectron-positron pair production. We discuss this analogy and describe the\nimplications of this analysis for the mechanics of biopolymer filament bundles\nof various types under compression."
    },
    {
        "anchor": "Dynamics of linear polymers in random media: We study phenomenological scaling theories of the polymer dynamics in random\nmedia, employing the existing scaling theories of polymer chains and the\npercolation statistics. We investigate both the Rouse and the Zimm model for\nBrownian dynamics and estimate the diffusion constant of the center-of-mass of\nthe chain in such disordered media. For internal dynamics of the chain, we\nestimate the dynamic exponents. We propose similar scaling theory for the\nreptation dynamics of the chain in the framework of Flory theory for the\ndisordered medium. The modifications in the case of correlated disordered are\nalso discussed.",
        "positive": "Polymer Shape Anisotropy and the Depletion Interaction: We calculate the second and third virial coefficients of the effective\nsphere-sphere interaction due to polymer depletion. By utilizing the anisotropy\nof a typical polymer conformation, we can consider polymers that are roughly\nthe same size as the spherical inclusions. We argue that recent experiments can\nconfirm this anisotropy."
    },
    {
        "anchor": "Investigating the influence of different thermodynamic paths on the\n  structural relaxation in a glass forming polymer melt: We present results from Molecular Dynamics simulations of the thermal glass\ntransition in a dense polymer melt. In previous work we compared the simulation\ndata with the idealized version of mode coupling theory (MCT) and found that\nthe theory provides a good description of the dynamics above the critical\ntemperature. In order to investigate the influence of different thermodynamic\npaths on the structural relaxation (alpha-process), we performed simulations\nfor three different pressures and are thus able to give a sketch of the\ncritical line of MCT in the pressure-temperature-plane [(p,T)-plane], where,\naccording to the idealised version of MCT, an ergodic-nonergodic transition\nshould occur. Furthermore, by cooling our system along two different paths (an\nisobar and an isochor), with the same impact point on the critical line, we\ndemonstrate that neither the critical temperature nor the exponent gamma depend\non the chosen path.",
        "positive": "Geometrically controlled snapping transitions in shells with curved\n  creases: Curvature and mechanics are intimately connected for thin materials, and this\ncoupling between geometry and physical properties is readily seen in folded\nstructures from intestinal villi and pollen grains, to wrinkled membranes and\nprogrammable metamaterials. While the well-known rules and mechanisms behind\nfolding a flat surface have been used to create deployable structures and shape\ntransformable materials, folding of curved shells is still not fundamentally\nunderstood. Curved shells naturally deform by simultaneously bending and\nstretching, and while this coupling gives them great stability for engineering\napplications, it makes folding a surface of arbitrary curvature a non-trivial\ntask. Here we discuss the geometry of folding a creased shell, and demonstrate\ntheoretically the conditions under which it may fold continuously. When these\nconditions are violated we show, using experiments and simulations, that shells\nundergo rapid snapping motion to fold from one stable configuration to another.\nAlthough material asymmetry is a proven mechanism for creating this bifurcation\nof stability, for the case of a creased shell, the inherent geometry itself\nserves as a barrier to folding. We discuss here how two fundamental geometric\nconcepts, creases and curvature, combine to allow rapid transitions from one\nstable state to another. Independent of material system and length scale, the\ndesign rule that we introduce here explains how to generate snapping\ntransitions in arbitrary surfaces, thus facilitating the creation of\nprogrammable multi-stable materials with fast actuation capabilities."
    },
    {
        "anchor": "Nematic bits and universal logic gates: Liquid crystals (LCs) can host robust topological defect structures that\nessentially determine their optical and elastic properties. Although recent\nexperimental progress enables precise control over localization and dynamics of\nnematic LC defects, their practical potential for information storage and\nprocessing has yet to be explored. Here, we introduce the concept of nematic\nbits (nbits) by exploiting a quaternionic mapping from LC defects to the\nPoincar\\'e-Bloch sphere. Through theory and simulations, we demonstrate how\nsingle-nbit operations can be implemented using electric fields, in close\nanalogy with Pauli, Hadamard and other common quantum gates. Ensembles of\ntwo-nbit states can exhibit strong statistical correlations arising from\nnematoelastic interactions, which can be used as a computational resource.\nUtilizing nematoelastic interactions, we show how suitably arranged 4-nbit\nconfigurations can realize universal classical NOR and NAND gates. Finally, we\ndemonstrate the implementation of generalized logical functions that take\nvalues on the Poincar\\'e-Bloch sphere. These results open a new route towards\nthe implementation of classical and non-classical computation strategies in\ntopological soft matter systems.",
        "positive": "Dynamical Transitions in a Dragged Growing Polymer Chain: We extend the Rouse model of polymer dynamics to situations of non-stationary\nchain growth. For a dragged polymer chain of length $N(t) = t^\\alpha$, we find\ntwo transitions in conformational dynamics. At $\\alpha= 1/2$, the propagation\nof tension and the average shape of the chain change qualitatively, while at\n$\\alpha = 1 $ the average center-of-mass motion stops. These transitions are\ndue to a simple physical mechanism: a race duel between tension propagation and\npolymer growth. Therefore they should also appear for growing semi-flexible or\nstiff polymers. The generalized Rouse model inherits much of the versatility of\nthe original Rouse model: it can be efficiently simulated and it is amenable to\nanalytical treatment."
    },
    {
        "anchor": "Flexoelectric surface switching of bistable nematic devices: We report on a novel method of dynamically controlling the boundary\nconditions at the surface of a nematic liquid crystal using a surface\nflexoelectric effect. By moving the surface directors we show that one is able\nto manipulate defects which lie near the surface. This can be used to produce\nswitching of a nematic liquid crystal device between two states with very\nsimilar free energies. This results in a bistable device that can retain either\nstate with no applied voltage. Switching between the states occurs when the\nmovement of the surface directors rotates those in the bulk which are then able\nto create or annihilate defects which lie near the surface of the device.",
        "positive": "Structural Organization of Space Polymers: Extra-terrestrial polymers of glycine with iron have been characterized by\nmass spectrometry to have a core mass of 1494Da with dominant rod-like variants\nat m/z 1567 and m/z 1639 [1]. Several principal macro-structural morphologies\nare observed in solvent extracts from CV3 class meteoritic material. The first\nis an extended sheet of linked triskelia containing the 1494Da core entity that\nencloses gas bubbles in the solvent [1]. A second is of fiber-like crystals\nfound here, via X-ray diffraction, to be multiple-walled nanotubes made from a\nsquare lattice of the 1494Da polymer. A third is a dispersion of floating\nphantom-like short tubes of up to 100micron length [1] with characteristic\nangled bends that suggest the influence of a specific underlying protein\nstructure. Here it is proposed that the angled tubes are the observable result\nof a space-filling super-polymerization of 1638Da polymer subunits guided by\nthe tetragonal symmetry of linking silicon bonds. Distorted hexagonal sheets\nare linked by perpendicular subunits in a three-dimensional hexagonal diamond\nstructure to fill the largest possible volume. This extended very low-density\nstructure is conjectured to have dominated in a process of chemical selection\nbecause it captured a maximum amount of molecular raw material in the ultra-low\ndensity of molecular clouds or of the proto-solar nebula. This could have led\nultimately to the accretion of the earliest planetary bodies."
    },
    {
        "anchor": "Modelling planar kirigami metamaterials as generalized elastic continua: Kirigami metamaterials dramatically change their shape through a coordinated\nmotion of nearly rigid panels and flexible slits. Here, we study a model system\nfor mechanism-based planar kirigami featuring periodic patterns of\nquadrilateral panels and rhombi slits, with the goal of predicting their\nengineering scale response to a broad range of loads. We develop a generalized\ncontinuum model based on the kirigami's effective (cell-averaged) nonlinear\ndeformation, along with its slit actuation and gradients thereof. The model\naccounts for three sources of elasticity: a strong preference for the effective\nfields to match those of a local mechanism, inter-panel stresses arising from\ngradients in slit actuation, and distributed hinge bending. We provide a\nfinite-element formulation of this model and implement it using the commercial\nsoftware Abaqus. Simulations of the model agree quantitatively with experiments\nacross designs and loading conditions.",
        "positive": "On the applicability of density dependent effective interactions in\n  cluster-forming systems: We systematically studied the validity and transferability of effective,\ncoarse-grained, pair potentials in ultrasoft colloidal systems. We focused on\namphiphilic dendrimers, macromolecules which can aggregate into clusters of\noverlapping particles to minimize the contact area with the surrounding\n(implicit) solvent. Simulations were performed for both the monomeric and\ncoarse-grained model in the liquid phase at densities ranging from infinite\ndilution up to values close to the freezing point. For every state point, each\nmacromolecule was mapped onto a single interaction site and the effective pair\npotential was computed using a coarse-graining technique based on\nforce-matching. We found excellent agreement between the spatial dendrimer\ndistributions obtained from the coarse-grained and microscopically detailed\nsimulations at low densities, where the macromolecules were distributed\nhomogeneously in the system. However, the agreement deteriorated significantly\nwhen the density was increased further and the cluster occupation became more\npolydisperse. Under these conditions, the effective pair potential of the\ncoarse-grained model can no longer be computed by averaging over the whole\nsystem, but the local density needs to be taken into account instead."
    },
    {
        "anchor": "A field-oriented chain of dipolar particles in elongational flow: We study the behavior of an isolated field-oriented chain of dipolar\nparticles in elongational fluid flow. Our main goal is to emphasize the effect\nof dipolar interactions on the chain's contribution to the pressure tensor and\nto the viscosities of a dilute suspension of these linear aggregates. In our\nmodel, despite the overall rigid appearance of the chain at rest, the\nconstituent beads may move slightly relative to one another, conferring a\ncertain degree of flexibility to the chain. This flexibility is quantified in\nterms of a dimensionless parameter, $\\lambda^{-1}$, comparing thermal and\ndipolar energies. We perform an expansion in $\\lambda^{-1}$, and obtain the\nfirst correction to the rigid chain contribution to the Kramers' pressure\ntensor for different flow geometries. The interplay of the elongational flow\nfield and the field-induced chain orientation gives rise to a rich variety of\nscenarios. We compute the elongational, shear, and rotational viscosities in\nsome representative situations.",
        "positive": "Geometric background charge: dislocations on capillary bridges: Recent experiments have shown that colloidal crystals confined to weakly\ncurved capillary bridges introduce groups of dislocations organized into\n`pleats' as means to relieve the stress caused by the Gaussian curvature of the\nsurface. We consider the onset of this curvature-screening mechanism, by\nexamining the energetics of isolated dislocations and interstitials on\ncapillary bridges with free boundaries. The boundary provides an essential\ncontribution to the problem, akin to a background charge that \"neutralizes\" the\nunbalanced integrated curvature of the surface. This makes it favorable for\ntopologically neutral dislocations and groups of dislocations - rather than\ntopologically charged disclinations and scars - to relieve the stress caused by\nthe unbalanced gaussian curvature of the surface. This effect applies to any\ncrystal on a surface with non-vanishing integrated Gaussian curvature and\nstress-free boundary conditions.\n  We corroborate the analytic results by numerically computing the energetics\nof a defected lattice of springs confined to surfaces with weak positive and\nnegative curvature"
    },
    {
        "anchor": "Small-Angle X-ray Scattering Unveils the Internal Structure of Lipid\n  Nanoparticles: Lipid nanoparticles own a remarkable potential in nanomedicine, only\npartially disclosed. While the clinical use of liposomes and cationic\nlipid-nucleic acid complexes is well-established, liquid lipid nanoparticles\n(nanoemulsions), solid lipid nanoparticles, and nanostructured lipid carriers\nhave even greater potential. However, they face obstacles in being used in\nclinics due to a lack of understanding about the molecular mechanisms\ncontrolling their drug loading and release, interactions with the biological\nenvironment (such as the protein corona), and shelf-life stability. To create\neffective drug delivery carriers and successfully translate bench research to\nclinical settings, it is crucial to have a thorough understanding of the\ninternal structure of lipid nanoparticles. Through synchrotron small-angle\nX-ray scattering experiments, we determined the spatial distribution and\ninternal structure of the nanoparticles' lipid, surfactant, and the water in\nthem. The nanoparticles themselves have a barrel-like shape that consists of\ncoplanar lipid platelets (specifically cetyl palmitate) that are partially\ncovered by polysorbate 80 surfactant and retain a small amount of hydration\nwater. Although the platelet structure was expected, the presence of surfactant\nmolecules forming sticky patches between adjacent platelets challenges the\nclassical core-shell model used to describe solid lipid nanoparticles.\nAdditionally, the surfactant partially covers the water-nanoparticle interface,\nallowing certain lipid regions to come into direct contact with surrounding\nwater. These structural features play a significant role in drug loading and\nrelease, biological fluid interaction, and nanoparticle stability, making these\nfindings valuable for the rational design of lipid-based nanoparticles.",
        "positive": "Effect of Succinonitrile on Ion Transport in PEO-based Lithium Ion\n  Battery Electrolytes: We report the ion transport mechanisms in succinonitrile (SN) loaded solid\npolymer electrolytes containing polyethylene oxide (PEO) and dissolved lithium\nbis(trifluoromethane)sulphonamide (LiTFSI) salt using molecular dynamics\nsimulations. We investigated the effect of temperature and loading of SN on ion\ntransport and relaxation phenomenon in PEO-LiTFSI electrolytes. It is observed\nthat SN increases the ionic diffusivities in PEO-based solid polymer\nelectrolytes and makes them suitable for battery applications. Interestingly,\nthe diffusion coefficient of TFSI ions is an order of magnitude higher than the\ndiffusion coefficient of lithium ions across the range of temperatures and\nloadings integrated. By analyzing different relaxation timescales and examining\nthe underlying transport mechanisms in SN-loaded systems, we find that the\ndiffusivity of TFSI ions correlates excellently with the Li-TFSI ion-pair\nrelaxation timescales. In contrast, our simulations predict distinct transport\nmechanisms for Li-ions in SN-loaded PEO-LiTFSI electrolytes. Explicitly, the\ndiffusivity of lithium ions cannot be uniquely determined by the ion-pair\nrelaxation timescales but additionally depends on the polymer segmental\ndynamics. On the other hand, the SN loading induced diffusion coefficient at a\ngiven temperature does not correlate with either the ion-pair relaxation\ntimescales or the polymer segmental relaxation timescales."
    },
    {
        "anchor": "Non-reciprocal interactions spatially propagate fluctuations in a 2D\n  Ising model: Motivated by the anisotropic interactions between fish, we implement\nspatially anisotropic and therefore non-reciprocal interactions in the 2D Ising\nmodel. First, we show that the model with non-reciprocal interactions alters\nthe system critical temperature away from that of the traditional 2D Ising\nmodel. Further, local perturbations to the magnetization in this\nout-of-equilibrium system manifest themselves as traveling waves of spin states\nalong the lattice, also seen in a mean-field model of our system. The speed and\ndirectionality of these traveling waves are controllable by the orientation and\nmagnitude of the non-reciprocal interaction kernel as well as the proximity of\nthe system to the critical temperature.",
        "positive": "Far From Threshold Buckling Analysis of Thin Films: Thin films buckle easily and form wrinkled states in regions of well defined\nsize. The extent of a wrinkled region is typically assumed to reflect the zone\nof in-plane compressive stresses prior to buckling, but recent experiments on\nultrathin sheets have shown that wrinkling patterns are significantly longer\nand follow different scaling laws than those predicted by standard buckling\ntheory. Here we focus on a simple setup to show the striking differences\nbetween near-threshold buckling and the analysis of wrinkle patterns in very\nthin films, which are typically far from threshold."
    },
    {
        "anchor": "Entropy-Driven Attraction of Heavy Spheres in a Harmonically Driven Bath\n  of Poppy Seeds: We develop the simplest possible theory that gives reason of the recent\nexperimental observations that two heavy spheres, immersed into a mono-layer\nbath of poppy seeds, attract one another when shaken harmonically in a single\nhorizontal direction. Their attraction is so strong that the two spheres remain\nbound during hundreds of driving periods. The paper consists of three\nindependently readable Chapters, with only a few inter-chapter references. The\nfirst Chapter concerns itself with the the motion of a roller amidst a\nhorizontally shaken sea of poppy seeds, under the Assumption of equal phase for\nrotational and translation velocities. The second Chapter details how this\npredicts the observed longitudinal diffusion of a single sphere in a bath of\npoppy seeds. The third Chapter shows how to retrieve all relevant physical\nparameters from experiment: viscosity of the seed bath, friction of the heavy\nspheres with the harmonically moving substrate, equilibrium rates for\ndissociation of bound pairs or binding of lone pairs, and the full Gibbs\npotential surface as a function of experimentally accessible parameters.",
        "positive": "Red blood cells and other non-spherical capsules in shear flow:\n  oscillatory dynamics and the tank-treading-to-tumbling transition: We consider the motion of red blood cells and other non-spherical\nmicrocapsules dilutely suspended in a simple shear flow. Our analysis indicates\nthat depending on the viscosity, membrane elasticity, geometry and shear rate,\nthe particle exhibits either tumbling, tank-treading of the membrane about the\nviscous interior with periodic oscillations of the orientation angle, or\nintermittent behavior in which the two modes occur alternately. For red blood\ncells, we compute the complete phase diagram and identify a novel\ntank-treading-to-tumbling transition at low shear rates. Observations of such\nmotions coupled with our theoretical framework may provide a sensitive means of\nassessing capsule properties."
    },
    {
        "anchor": "Membrane domain formation induced by binding/unbinding of\n  curvature-inducing molecules onto both membrane surfaces: The domain formation of curvature-inducing molecules, such as peripheral or\ntransmembrane proteins and conical surfactants, is studied in thermal\nequilibrium and nonequilibrium steady states using meshless membrane\nsimulations. These molecules can bind onto both surfaces of a bilayer membrane\nand also move to the opposite leaflet by a flip-flop. In symmetric conditions\nfor the two leaflets, the membrane domains form checkerboard patterns in\naddition to stripe and spot patterns. The unbound membrane stabilizes the\nvertices of the checkerboard. In asymmetric conditions, the domains form\nkagome-lattice and thread-like domains. In the nonequilibrium steady states, a\nflow of the binding molecules between the upper and lower solutions can occur\nvia the flip-flop.",
        "positive": "Mechanical basis and topological routes to cell elimination: Cell layers eliminate unwanted cells through the extrusion process, which\nunderlines healthy versus flawed tissue behaviors. Although several biochemical\npathways have been identified, the underlying mechanical basis including the\nforces involved in cellular extrusion remain largely unexplored. Utilizing a\nphase-field model of a three-dimensional cell layer, we study the interplay of\ncell extrusion with cell-cell and cell-substrate interactions, in a flat\nmonolayer. Independent tuning of cell-cell versus cell-substrate adhesion\nforces reveals that extrusion events can be distinctly linked to defects in\nnematic and hexatic orders associated with cellular arrangements. Specifically,\nwe show that by increasing relative cell-cell adhesion forces the cell\nmonolayer can switch between the collective tendency towards five-fold,\nhexatic, disclinations relative to half-integer, nematic, defects for extruding\na cell. We unify our findings by accessing three-dimensional mechanical stress\nfields to show that an extrusion event acts as a mechanism to relieve localized\nstress concentration."
    },
    {
        "anchor": "Influence of fine particles on the stability of a humid granular pile: We have investigated by rotating drum experiments the influence of a small\namount of fine particles on the stability of a granular heap. The fine\nparticles are shown to have a strong and ambivalent influence. For low fine\nparticle content, the heap destabilizes by avalanches, and the fine particles\ntend to fluidize the heap. In contrast, for high fine particle content, they\nincrease the cohesion of the heap, which destabilizes through stick-slip at the\ndrum wall. We interpret and model the fluidification in the avalanching regime,\nwhich we show is independent of humidity, by granular lubrication\nconsiderations, whereas the stick-slip behavior, highly dependent on humidity,\nis understood by a solid friction model.",
        "positive": "Fluidization of epithelial sheets by active cell rearrangements: We theoretically explore fluidization of epithelial tissues by active T1\nneighbor exchanges. We show that the geometry of cell-cell junctions encodes\nimportant information about the local features of the energy landscape, which\nwe support by an elastic theory of T1 transformations. Using a 3D vertex model,\nwe show that the degree of active noise driving forced cell rearrangements\ngoverns the stress-relaxation time-scale of the tissue. We study tissue\nresponse to in-plane shear at different time scales. At short time, the tissue\nbehaves as a solid, whereas its long-time fluid behavior can be associated with\nan effective viscosity which scales with the rate of active T1 transformations.\nFurthermore, we develop a coarse-grained theory, where we treat the tissue as\nan active fluid and confirm the results of the vertex model. The impact of cell\nrearrangements on tissue shape is illustrated by studying axial compression of\nan epithelial tube."
    },
    {
        "anchor": "The quantum character of buckling instabilities in thin rods: Here the buckling of inextensible rods due to axial body forces is mapped to\n1d, nonrelativistic, time-independent quantum mechanics. Focusing on the\npedagogical case of rods confined to 2d, three simple and physically realizable\napplications of the mapping are given in detail; the quantum counterparts of\nthese are particle in a box, particle in a delta-function well, and particle in\na triangular well. A fourth application examines the buckling counterpart of a\nquantum many-body problem (in the Hartree approximation). Through a fifth\napplication, given in the form of an exercise, the reader can explore the\nsurprising consequences of adding a second transverse dimension to the rod\nbuckling problem and imposing periodic boundary conditions.",
        "positive": "Swimming of an assembly of rigid spheres at low Reynolds number: A matrix formulation is derived for the calculation of the swimming speed and\nthe power required for swimming of an assembly of rigid spheres immersed in a\nviscous fluid of infinite extent. The spheres may have arbitrary radii and may\ninteract with elastic forces. The analysis is based on the Stokes mobility\nmatrix of the set of spheres, defined in low Reynolds number hydrodynamics. For\nsmall amplitude swimming optimization of the swimming speed at given power\nleads to an eigenvalue problem. The method allows straightforward calculation\nof the swimming performance of structures modeled as assemblies of interacting\nrigid spheres."
    },
    {
        "anchor": "Electric field of DNA in solution: who is in charge?: In solution, DNA is a highly charged macromolecule which bears a unit of\nnegative charge on each phosphate of its sugar-phosphate backbone. Although\npartially compensated by counterions adsorbed at or condensed near it, DNA\nstill produces a substantial electric field in its vicinity, which is screened\nby buffer electrolyte at longer distances from the DNA. Such field has been\nexplored so far predominantly within the scope of a primitive model of the\nelectrolytic solution, not considering more complicated structural effects of\nthe water solvent. In this paper we investigate the distribution of electric\nfield around DNA using linear response nonlocal electrostatic theory, applied\nhere for helix-specific charge distributions, and compare the predictions of\nsuch theory with specially performed fully atomistic large scale molecular\ndynamics simulations. The main finding of this study is that oscillations in\nthe electrostatic potential distribution are present around DNA, caused by the\noverscreening effect of structured water. Surprisingly, electrolyte ions at\nphysiological concentrations do not strongly disrupt these oscillations, and\nrather distribute according to these oscillating patterns, indicating that\nwater structural effects dominate the short-range electrostatics. We also show\nthat (i) structured water adsorbed in the grooves of DNA lead to a positive\nelectrostatic potential core, (ii) the Debye length some 10 {\\AA} away from the\nDNA is reduced, effectively renormalised by the helical pitch of the DNA, and\n(iii) Lorentzian contributions to the nonlocal dielectric function of water,\neffectively reducing the dielectric constant close to the DNA, enhances the\noverall electric field. The impressive agreement between the atomistic\nsimulations and the developed theory substantiates the use of nonlocal\nelectrostatics when considering solvent effects in molecular processes in\nbiology.",
        "positive": "Long-range interaction between dust grains in plasma: The nature of long-range interactions between dust grains in plasma is\ndiscussed. The dust grain interaction potential within a cell model of dusty\nplasma is introduced. The attractive part of intergrain potential is described\nby multipole interaction between two electro-neutral cells. This allowed us to\ndraw an analogy with molecular liquids where the attraction between molecules\nis determined by dispersion forces. The main ideas of the fluctuation theory\nfor electrostatic field in a cell model are formulated, and the dominating\ncontribution to the attractive part of intergrain potential is obtained."
    },
    {
        "anchor": "Stress-strain behavior and geometrical properties of packings of\n  elongated particles: We present a numerical analysis of the effect of particle elongation on the\nquasistatic behavior of sheared granular media by means of the Contact Dynamics\nmethod. The particle shapes are rounded-cap rectangles characterized by their\nelongation. The macroscopic and microstructural properties of several packings\nsubjected to biaxial compression are analyzed as a function of particle\nelongation. We find that the shear strength is an increasing linear function of\nelongation. Performing an additive decomposition of the stress tensor based on\na harmonic approximation of the angular dependence of branch vectors, contact\nnormals and forces, we show that the increasing mobilization of friction force\nand the associated anisotropy are key effects of particle elongation. These\neffects are correlated with partial nematic ordering of the particles which\ntend to be oriented perpendicular to the major principal stress direction and\nform side-to-side contacts. However, the force transmission is found to be\nmainly guided by cap-to-side contacts, which represent the largest fraction of\ncontacts for the most elongated particles. Another interesting finding is that,\nin contrast to shear strength, the solid fraction first increases with particle\nelongation, but declines as the particles become more elongated. It is also\nremarkable that the coordination number does not follow this trend so that the\npackings of more elongated particles are looser but more strongly connected.",
        "positive": "On the Formation of Unstirred Layer in Osmotically Driven Flow: Osmotically driven flow across a semi-permeable membrane under a constant\nstatic pressure difference is revisited with referring to the previous reports\nfor reverse osmosis. A few mathematical techniques for obtaining the\napproximate solution, such as that for inverse problems used in the field of\nheat transfer, are presented with an emphasis on the nonlinear boundary\ncondition and the time-dependent solvent flow-rate. It is concluded that the\nlayer is spontaneously formed by osmosis rapidly in the time scaled by $\\sim\n{\\rm O}\\bigl(\\sqrt{t}\\bigr)$, and that the layer thickness grows with no upper\nlimit in an infinite time interval. Based on the obtained solution, we will\nalso discuss the thermodynamical output work in an irreversible process which\nis extracted from the system as an osmotic engine."
    },
    {
        "anchor": "Density Reduction and Diffusion in Driven 2d-Colloidal Systems Through\n  Microchannels: The behavior of particles driven through a narrow constriction is\ninvestigated in experiment and simulation. The system of particles adapts to\nthe confining potentials and the interaction energies by a self-consistent\narrangement of the particles. It results in the formation of layers throughout\nthe channel and of a density gradient along the channel. The particles\naccommodate to the density gradient by reducing the number of layers one by one\nwhen it is energetically favorable. The position of the layer reduction zone\nfluctuates with time while the particles continuously pass this zone. The flow\nbehavior of the particles is studied in detail. The velocities of the particles\nand their diffusion behavior reflect the influence of the self-organized order\nof the system.",
        "positive": "Theory and simulation of the confined Lebwohl-Lasher model: We discuss the Lebwohl-Lasher model of nematic liquid crystals in a confined\ngeometry, using Monte Carlo simulation and mean-field theory. A film of\nmaterial is sandwiched between two planar, parallel plates that couple to the\nadjacent spins via a surface strength $\\epsilon_s$. We consider the cases where\nthe favoured alignments at the two walls are the same (symmetric cell) or\ndifferent (asymmetric or hybrid cell). In the latter case, we demonstrate the\nexistence of a {\\it single} phase transition in the slab for all values of the\ncell thickness. This transition has been observed before in the regime of\nnarrow cells, where the two structures involved correspond to different\narrangements of the nematic director. By studying wider cells, we show that the\ntransition is in fact the usual isotropic-to-nematic (capillary) transition\nunder confinement in the case of antagonistic surface forces. We show results\nfor a wide range of values of film thickness, and discuss the phenomenology\nusing a mean-field model."
    },
    {
        "anchor": "Long-range dynamic correlations in confined suspensions: Hydrodynamic interactions between particles confined in a liquid-filled\nlinear channel are known to be screened beyond a distance comparable to the\nchannel width. Using a simple analytical theory and lattice-Boltzmann\nsimulations, we show that the hydrodynamic screening is qualitatively modified\nwhen the time-dependent response and finite compressibility of the host liquid\nare taken into account. Diffusive compression modes in the confined liquid\ncause the particles to have velocity correlations of unbounded range, whose\namplitude decays with time only as $t^{-3/2}$.",
        "positive": "Phases of granular segregation in a binary mixture: We present results from an extensive experimental investigation into granular\nsegregation of a shallow binary mixture in which particles are driven by\nfrictional interactions with the surface of a vibrating horizontal tray. Three\ndistinct phases of the mixture are established viz; binary gas (unsegregated),\nsegregation liquid and segregation crystal. Their ranges of existence are\nmapped out as a function of the system's primary control parameters using a\nnumber of measures based on Voronoi tessellation. We study the associated\ntransitions and show that segregation can be suppressed is the total filling\nfraction of the granular layer, $C$, is decreased below a critical value,\n$C_{c}$, or if the dimensionless acceleration of the driving, $\\gamma$, is\nincreased above a value $\\gamma_{c}$."
    },
    {
        "anchor": "Instabilities of vortices in a binary mixture of trapped Bose-Einstein\n  condensates: Role of excitations with positive and negative energies: Correspondence between frequency and energy spectra and biorthogonality\nconditions for the excitations of Bose-Einstein condensates described by\nGross-Pitaevskii model have been derived selfconsistently revealing several\nnovel aspects originating in nonselfadjoitness of the Bogoliubov operator. It\nhas been demonstrated that frequency resonances of the excitations with\npositive and negative energies can lead to their mutual annihilation and\nappearance of the collective modes with complex frequencies and zero energies.\nConditions for the avoided crossing of energy levels have also been discussed.\nGeneral theory has been verified both numerically and analytically in the weak\ninteraction limit considering an example of vortices in a binary mixture of\ncondensates. Growth of excitations with complex frequencies leads to spiraling\nof the unit and double vortices out of the condensate center to its periphery\nand to splitting of the double and higher order vortices to the unit ones.",
        "positive": "Orientational transition and complexation of DNA with anionic membranes:\n  weak and intermediate electrostatic coupling: We characterize the role of charge correlations in the adsorption of a short,\nrod-like anionic polyelectrolyte onto a similarly charged membrane. Our theory\nreveals two different mechanisms driving the like-charge\npolyelectrolyte-membrane complexation: in weakly charged membranes, repulsive\npolyelectrolyte-membrane interactions lead to the interfacial depletion and a\nparallel orientation of the polyelectrolyte with respect to the membrane; while\nin the intermediate membrane charge regime, the interfacial counterion excess\ngives rise to an attractive \"salt-induced\" image force. This furthermore\nresults in an orientational transition from a parallel to a perpendicular\nconfiguration and a subsequent short-ranged like-charge adsorption of the\npolyelectrolyte to the substrate. A further increase of the membrane charge\nengenders a charge inversion, originating from surface-induced ionic\ncorrelations, that act as a separate mechanism capable of triggering the\nlike-charge polyelectrolyte-membrane complexation over an extended distance\ninterval from the membrane surface. The emerging picture of this complexation\nphenomenon identifies the interfacial \"salt-induced\" image forces as a powerful\ncontrol mechanism in polyelectrolyte-membrane complexation."
    },
    {
        "anchor": "Torsional Oscillations of a Rotating Column of $^3$He-B: We have analysed the axisymmetric and non-axisymmetric modes of a continuum\nof vortices in a rotating superfluid. We have investigated how changing the\ntemperature affects the growth rate of the disturbances. We find that, in the\nlong axial wavelength limit the condition q=alpha/(1-alpha')=1, where alpha and\nalpha' are temperature-dependent mutual friction parameters, is the crossover\nbetween damped and propagating Kelvin waves. Thus at temperatures for which\nq>1, perturbations on the vortices are unlikely to cause vortex reconnections\nand turbulence. These results are in agreement with the recent discovery of\nFinne et al (2003} of an intrinsic condition for the onset of quantum\nturbulence in $^3$He-B.",
        "positive": "Living clusters and crystals from low density suspensions of active\n  colloids: Recent studies aimed at investigating artificial analogs of bacterial\ncolonies have shown that low-density suspensions of self-propelled particles\nconfined in two dimensions can assemble into finite aggregates that merge and\nsplit, but have a typical size that remains constant (living clusters). In this\nLetter we address the problem of the formation of living clusters and crystals\nof active particles in three dimensions. We study two systems: self-propelled\nparticles interacting via a generic attractive potential and colloids that can\nmove towards each other as a result of active agents (e.g. by molecular\nmotors). In both cases fluid-like `living' clusters form. We explain this\ngeneral feature in terms of the balance between active forces and regression to\nthermodynamic equilibrium. This balance can be quantified in terms of a\ndimensionless number that allows us to collapse the observed clustering\nbehaviour onto a universal curve. We also discuss how active motion affects the\nkinetics of crystal formation."
    },
    {
        "anchor": "Role of disorder in finite-amplitude shear of a 2D jammed material: A material's response to small but finite deformations can reveal the roots\nof its response to much larger deformations. Here, we identify commonalities in\nthe responses of 2D soft jammed solids with different amounts of disorder. We\ncyclically shear the materials while tracking their constituent particles, in\nexperiments that feature a stable population of repeated structural\nrelaxations. Using bidisperse particle sizes creates a more amorphous material,\nwhile monodisperse sizes yield a more polycrystalline one. We find that the\nmaterials' responses are very similar, both at the macroscopic, mechanical\nlevel and in the microscopic motions of individual particles. However, both\nlocally and in bulk, crystalline arrangements of particles are stiffer (greater\nelastic modulus) and less likely to rearrange. Our work supports the idea of a\ncommon description for the responses of a wide array of materials.",
        "positive": "Ionic Structure and Decay Length in Highly-Concentrated Confined\n  Electrolytes: We use molecular dynamics simulations of the primitive model of electrolytes\nto study the ionic structure in aqueous monovalent electrolyte solutions\nconfined by charged planar interfaces over a wide range of electrolyte\nconcentration, interfacial separation, surface charge density, and ion size.\nThe investigations are inspired by recent experiments that have directly\nmeasured the increase in the decay length for highly-concentrated electrolytes\nwith increase in concentration. The behavior of ions in the nanoconfinement\ncreated by the interfaces is probed by evaluating the ionic density profiles,\nnet charge densities, screening factors, and decay length associated with the\nscreening of the charged interface. Results show the presence of two distinct\nregimes of screening behavior as the concentration is changed from 0.1 M to 2.5\nM for a wide range of electrolyte systems generated by tuning the interfacial\nseparation, surface charge density, and ionic size. For low concentrations, the\nscreening factor exhibits a monotonic decay to 0 with a decay length that\ndecreases sharply with increasing concentration. For high concentrations\n($\\gtrsim 1$ M), the screening factor has a non-monotonic behavior signaling\ncharge inversion and formation of structured layers of ions near the\ninterfaces. The decay length under these conditions rises with increasing\nconcentration, exhibiting a power-law behavior. To complement the simulation\nresults, a variational approach is developed that produces charge densities\nwith characteristics consistent with those observed in simulations. The results\ndemonstrate the relation between the rise in the strength of steric\ncorrelations and the changes in the screening behavior."
    },
    {
        "anchor": "Experimental and molecular dynamics study of the ionic conductivity in\n  aqueous LiCl electrolytes: Lithium chloride LiCl is widely used as a prototype system to study the\nstrongly dissociated 1-1 electrolyte solution. Here, we combined experimental\nmeasurements and classical molecular dynamics simulations to study the ion\nconduction in this system. Ionic conductivities were reported at both\n20$^\\circ$C and 50$^\\circ$C from experiments and compared to results from\nmolecular dynamics simulations. The main finding of this work is that\ntransference numbers of Li$^+$ and Cl$^-$ become comparable at high\nconcentration. This phenomenon is independent of the force fields employed in\nthe simulation and may be resulted from the ion-specific concentration\ndependence of mobility.",
        "positive": "Extensional Instability in Electro-Osmotic Microflows of Polymer\n  Solutions: Fluid transport in microfluidic systems typically is laminar due to the low\nReynolds number characteristic of the flow. The inclusion of suspended polymers\nimparts elasticity to fluids, allowing instabilities to be excited when\nsubstantial polymer stretching occurs. For high molecular weight polymer chains\nwe find that flow velocities achievable by standard electro-osmotic pumping are\nsufficient to excite extensional instabilities in dilute polymer solutions. We\nobserve a dependence in measured fluctuations on polymer concentration which\nplateaus at a threshold corresponding to the onset of significant molecular\ncrowding in macromolecular solutions; plateauing occurs well below the overlap\nconcentration. Our results show that electro-osmotic flows of complex fluids\nare disturbed from the steady regime, suggesting potential for enhanced mixing\nand requiring care in modeling the flow of complex liquids such as biopolymer\nsuspensions."
    },
    {
        "anchor": "Understanding depletion induced like-charge attraction from\n  self-consistent field model: The interaction force between likely charged particles/surfaces is usually\nrepulsive due to the Coulomb interaction. However, the counterintuitive\nlike-charge attraction in electrolytes has been frequently observed in\nexperiments, which has been theoretically debated for a long time. It is widely\nknown that the mean field Poisson-Boltzmann theory cannot explain or predict\nthis anomalous feature since it ignores many-body properties. In this paper, we\ndevelop efficient algorithm and perform the force calculation between two\ninterfaces using a set of self-consistent equations which properly takes into\naccount the electrostatic correlation and the dielectric-boundary effects. By\nsolving the equations and calculating the pressure with the Debye-charging\nprocess, we show that the self-consistent equations could be used to study the\nattraction between like-charge surfaces from weak-coupling to mediate-coupling\nregime, and that the attraction is due to the electrostatics-driven entropic\nforce which is significantly enhanced by the dielectric depletion of mobile\nions. A systematic investigation shows that the interaction forces can be tuned\nby material permittivity, ionic size and valence, and salt concentration, and\nthat the like-charge attraction exists only for specific regime of these\nparameters.",
        "positive": "Tailored Nematic and Magnetization Profiles on 2D Polygons: We study dilute suspensions of magnetic nanoparticles in a nematic host, on\ntwo-dimensional (2D) polygons. These systems are described by a nematic order\nparameter and a spontaneous magnetization, in the absence of any external\nfields. We study the stable states in terms of stable critical points of an\nappropriately defined free energy, with a nemato-magnetic coupling energy. We\nnumerically study the interplay between the shape of the regular polygon, the\nsize of the polygon and the strength of the nemato-magnetic coupling for the\nmultistability of this prototype system. Our notable results include (i) the\nco-existence of stable states with domain walls and stable interior and\nboundary defects, (ii) the suppression of multistability for positive\nnemato-magnetic coupling, and (iii) the enhancement of multistability for\nnegative nemato-magnetic coupling."
    },
    {
        "anchor": "Lectures on Molecular- and Nano-scale Fluctuations in Water: This manuscript is the written form of three lectures delivered by David\nChandler at the International School of Physics \"Enrico Fermi\", Course CLXXVI -\n\"Complex materials in physics and biology\", in Varenna, Italy in July 2010. It\ndescribes the physical properties of water from a molecular perspective and how\nthese properties are reflected in the behaviors of water as a solvent. Theory\nof hydrophobicity and solvation of ions are topics included in the discussion.",
        "positive": "Magneto-electrical orientation of lipid-coated graphitic micro-particles\n  in solution: We demonstrate, for the first time, confinement of the orientation of\nmicron-sized graphitic flakes to a well-defined plane. We orient and\nrotationally trap lipid-coated highly ordered pyrolytic graphite (HOPG)\nmicro-flakes in aqueous solution using a combination of uniform magnetic and AC\nelectric fields and exploiting the anisotropic diamagnetic and electrical\nproperties of HOPG. Measuring the rotational Brownian fluctuations of\nindividual oriented particles in rotational traps, we quantitatively determine\nthe rotational trap stiffness, maximum applied torque and polarization\nanisotropy of the micro-flakes, as well as their dependency on the electric\nfield frequency. Additionally, we quantify interactions of the micro-particles\nwith adjacent glass surfaces with various surface treatments. We outline the\nvarious applications of this work, including torque sensing in biological\nsystems."
    },
    {
        "anchor": "Helical paths, gravitaxis, and separation phenomena for mass-anisotropic\n  self-propelling colloids: experiment versus theory: The self-propulsion mechanism of active colloidal particles often generates\nnot only translational but also rotational motion. For particles with an\nanisotropic mass density under gravity, the motion is usually influenced by a\ndownwards oriented force and an aligning torque. Here we study the trajectories\nof self-propelled bottom-heavy Janus particles in three spatial dimensions both\nin experiments and by theory. For a sufficiently large mass anisotropy, the\nparticles typically move along helical trajectories whose axis is oriented\neither parallel or antiparallel to the direction of gravity (i.e., they show\ngravitaxis). In contrast, if the mass anisotropy is small and rotational\ndiffusion is dominant, gravitational alignment of the trajectories is not\npossible. Furthermore, the trajectories depend on the angular self-propulsion\nvelocity of the particles. If this component of the active motion is strong and\nrotates the direction of translational self-propulsion of the particles, their\ntrajectories have many loops, whereas elongated swimming paths occur if the\nangular self-propulsion is weak. We show that the observed gravitational\nalignment mechanism and the dependence of the trajectory shape on the angular\nself-propulsion can be used to separate active colloidal particles with respect\nto their mass anisotropy and angular self-propulsion, respectively.",
        "positive": "Thermodynamics of imbibition in capillaries of double conical\n  structures-Hourglass, diamond, and sawtooth shaped capillaries-: Thermodynamics of imbibition (intrusion and extrusion) in capillaries of\ndouble conical structures is theoretically studied using the classical\ncapillary model. By extending the knowledge of the thermodynamics of a single\nconical capillary, not only the nature of spontaneous imbibition but that of\nforced imbibition under applied external pressure are clarified. Spontaneous\nimbibition in capillaries of double conical structure can be predicted from the\nLaplace pressure in a single conical capillary. To understand the forced\nimbibition process, the free energy landscape along the imbibition pathway is\ncalculated. This landscape shows either a maximum or a minimum. The former acts\nas the energy barrier and the latter acts as the trap for the liquid-vapor\nmeniscus so that the imbibition process can be either abrupt with a pressure\nhysteresis or gradual and continuous. The landscape also predicts a completely\nfilled, a half-filled and a completely empty state as the thermodynamically\nstable state. Furthermore, it also predicts a completely filled and a\nhalf-filled state of metastable liquid which can be prepared by the combination\nof the intrusion and the extrusion process. Our study could be useful for\nunderstanding various natural fluidic systems and for designing functional\nfluidic devices such as a diode, a switch etc."
    },
    {
        "anchor": "Evaporation-driven electrokinetic energy conversion: critical review,\n  parametric analysis and perspectives: Energy harvesting from evaporation has become a hot topic in the last couple\nof years. Researchers have speculated on several possible mechanisms.\nElectrokinetic energy conversion is the least hypothetical one. The basics of\npressure-driven electrokinetic phenomena of streaming current and streaming\npotential have long been established. The regularities of evaporation from\nporous media are also well known. However, coupling of these two classes of\nphenomena has not, yet, been seriously explored. In this critical review, we\nwill recapitalize and combine the available knowledge from these two fields to\nproduce a coherent picture of electrokinetic electricity generation during\nevaporation from (nano)porous materials. For illustration, we will consider\nseveral configurations, namely, single nanopores, arrays of nanopores, systems\nwith reduced area of electrokinetic-conversion elements and devices with side\nevaporation from thin nanoporous films. For the latter (practically the only\none studied experimentally), we will formulate a simple model describing\ncorrelations of system performance with such principal parameters as the\nnanoporous-layer length, width and thickness as well as the pore size,\npore-surface hydrophilicity, effective zeta-potential and electric conductivity\nin nanopores. These correlations will be qualitatively compared with\nexperimental data available in the literature. We will see that experimental\ndata not always are in agreement with the model predictions, which may be due\nto simplifying model assumptions but also because the mechanisms are different\nfrom the classical electrokinetic energy conversion. In particular, this\nconcerns the mechanisms of conversion of evaporation-driven ion streaming\ncurrents into electron currents in external circuits. We will also formulate\ndirections of future experimental and theoretical studies that could help\nclarify these issues.",
        "positive": "Elastic scattering loss of atoms from colliding Bose-Einstein condensate\n  wavepackets: Bragg diffraction of atoms by light waves has been used to create high\nmomentum components in a Bose-Einstein condensate. Collisions between atoms\nfrom two distinct momentum wavepackets cause elastic scattering that can remove\na significant fraction of atoms from the wavepackets and cause the formation of\na spherical shell of scattered atoms. We develop a slowly varying envelope\ntechnique that includes the effects of this loss on the condensate dynamics\ndescribed by the Gross-Pitaevski equation. Three-dimensional numerical\ncalculations are presented for two experimental situations: passage of a moving\ndaughter condensate through a non-moving parent condensate, and four-wave\nmixing of matter waves."
    },
    {
        "anchor": "Neural Network Model for Structure Factor of Polymer Systems: As an important physical quantity to understand the internal structure of\npolymer chains, the structure factor is being studied both in theory and\nexperiment. Theoretically, the structure factor of Gaussian chains have been\nsolved analytically, but for wormlike chains, numerical approaches are often\nused, such as Monte Carlo (MC) simulations, solving modified diffusion equation\n(MDE), etc. In those works, the structure factor needs to be calculated\ndifferently for different regions of the wave vector and chain rigidity, and\nsome calculation processes are resource consuming. In this work, by training a\ndeep neural network (NN), we obtained an efficient model to calculate the\nstructure factor of polymer chains, without considering different regions of\nwavenumber and chain rigidity. Furthermore, based on the trained neural network\nmodel, we predicted the contour and Kuhn length of some polymer chains by using\nscattering experimental data, and we found our model can get pretty reasonable\npredictions. This work provides a method to obtain structure factor for polymer\nchains, which is as good as previous, and with a more computationally\nefficient. Also, it provides a potential way for the experimental researchers\nto measure the contour and Kuhn length of polymer chains.",
        "positive": "Screening in two-dimensional foams: Using the Surface Evolver software, we perform numerical simulations of\npoint-like deformations in a two-dimensional foam. We study perturbations which\nare infinitesimal or finite, isotropic or anisotropic, and we either conserve\nor do not conserve the number of bubbles. We measure the displacement fields\naround the perturbation. Changes in pressure decrease exponentially with the\ndistance to perturbation, indicating a screening over a few bubble diameters."
    },
    {
        "anchor": "Finite size analysis of zero-temperature jamming transition under\n  applied shear stress: By finding local minima of an enthalpy-like energy, we can generate jammed\npackings of frictionless spheres under constant shear stress $\\sigma$ and\nobtain the yield stress $\\sigma_y$ by sampling the potential energy landscape.\nFor three-dimensional systems with harmonic repulsion, $\\sigma_y$ satisfies the\nfinite size scaling with the limiting scaling relation $\\sigma_y\\sim\\phi -\n\\phi_{_{c,\\infty}}$, where $\\phi_{_{c,\\infty}}$ is the critical volume fraction\nof the jamming transition at $\\sigma=0$ in the thermodynamic limit. The width\nor uncertainty of the yield stress decreases with decreasing $\\phi$ and decays\nto zero in the thermodynamic limit. The finite size scaling implies a length\n$\\xi\\sim (\\phi-\\phi_{_{c,\\infty}})^{-\\nu}$ with $\\nu=0.81\\pm 0.05$, which turns\nout to be a robust and universal length scale exhibited as well in the finite\nsize scaling of multiple quantities measured without shear and independent of\nparticle interaction. Moreover, comparison between our new approach and\nquasi-static shear reveals that quasi-static shear tends to explore low-energy\nstates.",
        "positive": "Logarithmic rate dependence in deforming granular materials: Rate-independence for stresses within a granular material is a basic tenet of\nmany models for slow dense granular flows. By contrast, logarithmic rate\ndependence of stresses is found in solid-on-solid friction, in geological\nsettings, and elsewhere. In this work, we show that logarithmic rate-dependence\noccurs in granular materials for plastic (irreversible) deformations that occur\nduring shearing but not for elastic (reversible) deformations, such as those\nthat occur under moderate repetitive compression. Increasing the shearing rate,\n\\Omega, leads to an increase in the stress and the stress fluctuations that at\nleast qualitatively resemble what occurs due to an increase in the density.\nIncreases in \\Omega also lead to qualitative changes in the distributions of\nstress build-up and relaxation events. If shearing is stopped at t=0, stress\nrelaxations occur with \\sigma(t)/ \\sigma(t=0) \\simeq A \\log(t/t_0). This\ncollective relaxation of the stress network over logarithmically long times\nprovides a mechanism for rate-dependent strengthening."
    },
    {
        "anchor": "Rolling friction for hard cylinder and sphere on viscoelastic solid: We calculate the friction force acting on a hard cylinder or spherical ball\nrolling on a flat surface of a viscoelastic solid. The rolling friction\ncoefficient depends non-linearly on the normal load and the rolling velocity.\nFor a cylinder rolling on a viscoelastic solid characterized by a single\nrelaxation time Hunter has obtained an exact result for the rolling friction,\nand our result is in very good agreement with his result for this limiting\ncase. The theoretical results are also in good agreement with experiments of\nGreenwood and Tabor. We suggest that measurements of rolling friction over a\nwide range of rolling velocities and temperatures may constitute an useful way\nto determine the viscoelastic modulus of rubber-like materials.",
        "positive": "Sensitive detection of ultra-weak adhesion states of vesicles by\n  interferometric microscopy: We have used an original analysis of reflection interference contrast\nmicroscopy (RICM) to detect an ultra-weak specific interaction between a\nglycolipid vesicle and a lectin-coated substrate. The membrane height\nfluctuations in the contact zone are observed with a high illumination\naperture; the membrane profile and the membrane-substrate distance are\nquantitatively determined using the new analysis, which accounts for multiple\ninterfaces and multiple incidence rays. We showed that this refined version of\nRICM theory is necessary, specifically in the case of intermediate\nmembranesubstrate distance (30 nm) and helped to discriminate between the\nultra-weak interaction and pure gravitational sedimentation"
    },
    {
        "anchor": "Understanding plastic deformation in thermal glasses from\n  single-soft-spot dynamics: By considering the low-frequency vibrational modes of amorphous solids,\nManning and Liu [Phys. Rev. Lett. 107, 108302 (2011)] showed that a population\nof \"soft spots\" can be identified that are intimately related to plasticity at\nzero temperature under quasistatic shear. In this work we track individual soft\nspots with time in a two-dimensional sheared thermal Lennard Jones glass at\ntemperatures ranging from deep in the glassy regime to above the glass\ntransition temperature. We show that the lifetimes of individual soft spots are\ncorrelated with the timescale for structural relaxation. We additionally\ncalculate the number of rearrangements required to destroy soft spots, and show\nthat most soft spots can survive many rearrangements. Finally, we show that\nsoft spots are robust predictors of rearrangements at temperatures well into\nthe super-cooled regime. Altogether, these results pave the way for mesoscopic\ntheories of plasticity of amorphous solids based on dynamical behavior of\nindividual soft spots.",
        "positive": "Shape deformation of lipid membranes by banana-shaped protein rods:\n  Comparison with isotropic inclusions and membrane rupture: The assembly of curved protein rods on fluid membranes is studied using\nimplicit-solvent meshless membrane simulations. As the rod curvature increases,\nthe rods on a membrane tube assemble along the azimuthal direction first and\nsubsequently along the longitudinal direction. Here, we show that both\ntransition curvatures decrease with increasing rod stiffness. For comparison,\ncurvature-inducing isotropic inclusions are also simulated. When the isotropic\ninclusions have the same bending rigidity as the other membrane regions, the\ninclusions are uniformly distributed on the membrane tubes and vesicles even\nfor large spontaneous curvature of the inclusions. However, the isotropic\ninclusions with much larger bending rigidity induce shape deformation and are\nconcentrated on the region of a preferred curvature. For high rod density, high\nrod stiffness, and/or low line tension of the membrane edge, the rod assembly\ninduces vesicle rupture, resulting in the formation of a high-genus vesicle. A\ngradual change in the curvature suppresses this rupture. Hence, large stress,\ncompared to the edge tension, induced by the rod assembly is the key factor\ndetermining rupture. For rod curvature with the opposite sign to the vesicle\ncurvature, membrane rupture induces inversion of the membrane, leading to\ndivision into multiple vesicles as well as formation of a high-genus vesicle."
    },
    {
        "anchor": "Influence of wetting properties on the hydrodynamic boundary condition\n  at a fluid-solid interface: It is well known that, at a macroscopic level, the boundary condition for a\nviscous fluid at a solid wall is one of \"no-slip\". The liquid velocity field\nvanishes at a fixed solid boundary. In this paper, we consider the special case\nof a liquid that partially wets the solid, i.e. a drop of liquid in equilibrium\nwith its vapor on the solid substrate has a finite contact angle. Using\nextensive Non-Equilibrium Molecular Dynamics (NEMD) simulations, we show that\nwhen the contact angle is large enough, the boundary condition can drastically\ndiffer (at a microscopic level) from a \"no-slip\" condition. Slipping lengths\nexceeding 30 molecular diameters are obtained for a contact angle of 140\ndegrees, characteristic of Mercury on glass. On the basis of a Kubo expression\nfor $\\delta$, we derive an expression for the slipping length in terms of\nequilibrium quantities of the system. The predicted behaviour is in very good\nagreement with the numerical results for the slipping length obtained in the\nNEMD simulations. The existence of large slipping lentgh may have important\nimplications for the transport properties in nanoporous media under such\n\"nonwetting\" conditions.",
        "positive": "Long Range Bond-Bond Correlations in Dense Polymer Solutions: The scaling of the bond-bond correlation function $C(s)$ along linear polymer\nchains is investigated with respect to the curvilinear distance, $s$, along the\nflexible chain and the monomer density, $\\rho$, via Monte Carlo and molecular\ndynamics simulations. % Surprisingly, the correlations in dense three\ndimensional solutions are found to decay with a power law $C(s) \\sim\ns^{-\\omega}$ with $\\omega=3/2$ and the exponential behavior commonly assumed is\nclearly ruled out for long chains. % In semidilute solutions, the density\ndependent scaling of $C(s) \\approx g^{-\\omega_0} (s/g)^{-\\omega}$ with\n$\\omega_0=2-2\\nu=0.824$ ($\\nu=0.588$ being Flory's exponent) is set by the\nnumber of monomers $g(\\rho)$ contained in an excluded volume blob of size\n$\\xi$. % Our computational findings compare well with simple scaling arguments\nand perturbation calculation. The power-law behavior is due to\nself-interactions of chains on distances $s \\gg g$ caused by the connectivity\nof chains and the incompressibility of the melt. %"
    },
    {
        "anchor": "Diffusion wave modes and oscillating motions in superfluid $He^3-A$: Diffusion vibrational modes are studied in superfluid $He^3-A$ in zero\nmagnetic fields for different angles between the orbital axis and the wave\nvector. The dispersion relation for these modes is found to depend on the wave\npolarization. It is shown that in addition to the normal component velocity,\nthe superfluid component velocity also oscillates in the diffusion modes of\n$He^3-A$. The frictional forces due to viscous waves in $He^3-A$, exerted in\nthe plane surface which is in contact with a superfluid liquid layer of finite\nthickness and performs a simple harmonic oscillatory motion, are calculated. We\nalso consider, volume of $He^3-A$ restricted by two parallel infinite surfaces,\nwhen the lower surface accomplishes simple harmonic oscillation and we\ncalculate the frictional forces exerted on surfaces. It is found that the\nfrictional force has not only parallel, but also a perpendicular component\nrelative to the direction of oscillations.",
        "positive": "Topological character of hydrodynamic screening in suspensions of hard\n  spheres: an example of universal phenomenon: Although in the case of polymer solutions the existence of hydrodynamic\nscreening is considered as established, use of the same methods for suspensions\nof hard spheres so far have failed to produce similar results. In this work we\nreconsider this problem. Using superposition of topological, combinatorial and\nLondon-style qualitative arguments, we prove the existence of screening in\nsuspensions. We show that the nature of hydrodynamic screening in suspensions\nis analogous to that known for the Meissner effect in superconductors. The\nextent of screening depends on volume fraction of hard spheres. The zero volume\nfraction limit corresponds to the normal state. The case of finite volume\nfractions-to the mixed state typical for superconductors of the second kind.\nSuch a state is becoming fully \"superconducting\" at some critical volume\nfraction for which the (zero frequency) relative viscosity diverges. Our\nanalytical results describing this divergence are in accord with known scaling\nresults obtained by Brady and Bicerano et al which are well supported by\nexperimental data. We provide theoretical explanation of the divergence of\nrelative viscosity in terms of a topological-type transition which\nmathematically can be made isomorphic to the more familiar Bose-Einstein\ncondensation transition. Because of this, the methods developed in this work\nare not limited to suspensions only. In concluding section we mention other\napplications of the developed formalism ranging from turbulence and\nmagnetohydrodynamics to high temperature superconductors, QCD, string models,\netc."
    },
    {
        "anchor": "Vibrational properties of inclusion complexes: the case of\n  indomethacin-cyclodextrin: Vibrational properties of inclusion complexes with cyclodextrins are studied\nby means of Raman spectroscopy and numerical simulation. In particular, Raman\nspectra of the non-steroidal, anti-inflammatory drug indomethacin undergo\nnotable changes in the energy range between 1600 and 1700 cm$^{-1}$ when\ninclusion complexes with cyclodextrins are formed. By using both \\emph{ab\ninitio} quantum chemical calculations and molecular dynamics, we studied how to\nrelate such changes to the geometry of the inclusion process, disentangling\nsingle-molecule effects, from changes in the solid state structure or\ndimerization processes.",
        "positive": "Granular Solid Hydrodynamics (GSH): from Quasi-Static Motion to Rapid\n  Dense Flow: {\\sc gsh} is a continuum mechanical theory constructed to qualitatively\naccount for a broad range of granular phenomena. To probe and demonstrate its\nwidth, simple solutions of {\\sc gsh} are related to granular phenomena and\nconstitutive models, including (i) for vanishing shear rates: static stress\ndistribution and propagation of elastic waves; (ii) at slow rates: critical\nstate, shear band, the models of hypoplasticity and barodesy; (iii) at higher\nrates: the MIDI-model, rapid dense flow in the Bagnold regime. A unified,\ndensely correlated understanding of granular physics emerges as a result of\nthese phenomena ordered and explained employing a single framework."
    },
    {
        "anchor": "Critical Nature of the Size Exponent of Polymers: On the basis of the thermodynamic theory of the excluded volume effects, we\nshow that the size exponent varies abruptly, depending on the change of the\nsegment concentration. For linear polymers, the exponent changes\ndiscontinuously from $\\nu=3/5$ for the isolated system ($\\bar{\\phi}=0$) in good\nsolvents to $\\nu=1/2$ in the finite concentration ($0<\\bar{\\phi}\\le1$), while\nfor branched polymers having $\\nu_{0}=1/4$, the corresponding exponent varies\nfrom $\\nu=1/2$ ($\\bar{\\phi}=0$) to $\\nu\\cong 1/3$ ($0<\\bar{\\phi}\\le1$).",
        "positive": "Plastic response and correlations in athermally sheared amorphous solids: The onset of irreversible deformation in low-temperature amorphous solids is\ndue to the accumulation of elementary events, consisting of spacially and\ntemporally localized atomic rearrangements involving only a few tens of atoms.\nRecently, numerical and experimental work addressed the issue of\nspatio-temporal correlations between these plastic events. Here, we provide\nfurther insight into these correlations by investigating, via molecular\ndynamics (MD) simulations, the plastic response of a two-dimensional amorphous\nsolid to artificially triggered local shear transformations. We show that while\nthe plastic response is virtually absent in as-quenched configurations, it\nbecomes apparent if a shear strain was previously imposed on the system.\nPlastic response has a four-fold symmetry which is characteristic of the shear\nstress redistribution following the local transformation. At high shear rate we\nreport evidence for a fluctuation-dissipation relation, connecting plastic\nresponse and correlation, which seems to break down if lower shear rates are\nconsidered."
    },
    {
        "anchor": "A fundamental measure theory for the sticky hard sphere fluid: We construct a density functional theory (DFT) for the sticky hard sphere\n(SHS) fluid which, like Rosenfeld's fundamental measure theory (FMT) for the\nhard sphere fluid [Phys. Rev. Lett. {\\bf 63}, 980 (1989)], is based on a set of\nweighted densities and an exact result from scaled particle theory (SPT). It is\ndemonstrated that the excess free energy density of the inhomogeneous SHS fluid\n$\\Phi_{\\text{SHS}}$ is uniquely defined when (a) it is solely a function of the\nweighted densities from Kierlik and Rosinberg's version of FMT [Phys. Rev. A\n{\\bf 42}, 3382 (1990)], (b) it satisfies the SPT differential equation, and (c)\nit yields any given direct correlation function (DCF) from the class of\ngeneralized Percus-Yevick closures introduced by Gazzillo and Giacometti [J.\nChem. Phys. {\\bf 120}, 4742 (2004)]. The resulting DFT is shown to be in very\ngood agreement with simulation data. In particular, this FMT yields the correct\ncontact value of the density profiles with no adjustable parameters. Rather\nthan requiring higher order DCFs, such as perturbative DFTs, our SHS FMT\nproduces them. Interestingly, although equivalent to Kierlik and Rosinberg's\nFMT in the case of hard spheres, the set of weighted densities used for\nRosenfeld's original FMT is insufficient for constructing a DFT which yields\nthe SHS DCF.",
        "positive": "Bistable molecular conductors with a field-switchable dipole group: A class of bistable \"stator-rotor\" molecules is proposed, where a stationary\nbridge (stator) connects the two electrodes and facilitates electron transport\nbetween them. The rotor part, which has a large dipole moment, is attached to\nan atom of the stator via a single sigma bond. Hydrogen bonds formed between\nthe rotor and stator make the symmetric orientation of the dipole unstable. The\nrotor has two potential minima with equal energy for rotation about the sigma\nbond. The dipole orientation, which determines the conduction state of the\nmolecule, can be switched by an external electric field that changes the\nrelative energy of the two potential minima. Both orientation of the rotor\ncorrespond to asymmetric current-voltage characteristics that are the reverse\nof each other, so they are distinguishable electrically. Such bistable\nstator-rotor molecules could potentially be used as parts of molecular\nelectronic devices."
    },
    {
        "anchor": "Disorder-induced neutral solitons in degenerate ground state polymers: In this letter, we study the effects of weak off-diagonal disorder on\nconjugated polymers with a doubly degenerate ground-state. We find that\ndisorder induces a finite density of neutral solitons in the lattice\ndimerization of a polymer chain. Interchain interactions result in a linear\npotential between the solitons and, if sufficiently strong, bind them into\npairs resulting in an exponential suppression of the soliton density. As\nneutral solitons carry spin 1/2, they contribute to the polymer's magnetic\nproperties. We calculate the magnetic susceptibility and suggest measurements\nof the magnetic susceptibility in {\\it trans}-polyacetylene at low\ntemperatures.",
        "positive": "Probing Polyelectrolyte Elasticity Using Radial Distribution Function: We study the effect of electrostatic interactions on the distribution\nfunction of the end-to-end distance of a single polyelectrolyte chain in the\nrodlike limit. The extent to which the radial distribution function of a\npolyelectrolyte is reproduced by that of a wormlike chain with an adjusted\npersistence length is investigated. Strong evidence is found for a universal\nscaling formula connecting the effective persistence length of a\npolyelectrolyte with its linear charge density and the Debye screening of its\nself-interaction. An alternative definition of the electrostatic persistence\nlength is proposed based on matching of the maximum of the distribution with\nthat of an effective wormlike chain, as opposed to the traditional matching of\nthe first or the second moments of the distributions. It is shown that this\ndefinition provides a more accurate probe of the affinity of the distribution\nto that of the wormlike chains, as compared to the traditional definition. It\nis also found that the length of a polyelectrolyte segment can act as a crucial\nparameter in determining its elastic properties."
    },
    {
        "anchor": "Elastic constants of nematic liquid crystals of uniaxial symmetry: We study in detail the influence of molecular interactions on the Frank\nelastic constants of uniaxial nematic liquid crystals composed of molecules of\ncylindrical symmetry. A brief summary of the status of theoretical development\nfor the elastic constants of nematics is presented. Considering a pair\npotential having both repulsive and attractive parts numerical calculations are\nreported for three systems MBBA, PAA and 8OCB. For these systems the\nlength-to-width ratio ${x_0}$ is estimated from the experimentally proposed\nstructure of the molecules. The repulsive interaction is represented by a\nrepulsion between hard ellipsoids of revolution (HER) and the attractive\npotential is represented by the quadrupole and dispersion interactions. From\nthe numerical results we observe that in the density range of nematics the\ncontribution of the quadrupole and dispersion interactions are small as\ncompared to the repulsive HER interaction. The inclusion of attractive\ninteraction reduces the values of elastic constants ratios. The temperature\nvariation of elastic constants ratios are reported and compared with the\nexperimental values. A reasonably good agreement between theory and experiment\nis observed.",
        "positive": "Random packing of rods in small containers: We conduct experiments and simulations to study the disordered packing of\nrods in small containers. Experiments study cylindrical rods with aspect ratio\nranging from 4 to 32; simulations use of spherocylinders with similar aspect\nratios. In all cases, rods pack randomly in cylindrical containers whose\nsmallest dimension is larger than the rod length. Packings in smaller\ncontainers have lower volume fractions than those in larger containers,\ndemonstrating the influence of the boundaries. The volume fraction extrapolated\nto infinite container size decreases with increasing aspect ratio, in agreement\nwith previous work. X-ray tomography experiments show that the boundary effects\ndepend on the orientation of the boundary, indicating a strong influence of\ngravity, whereas the simulation finds boundary effects that are purely\ngeometric. In all cases, the boundary influence extends approximately half a\nparticle length into the interior of the container."
    },
    {
        "anchor": "Statistical theory of correlations in random packings of hard particles: A random packing of hard particles represents a fundamental model for\ngranular matter. Despite its importance, analytical modeling of random packings\nremains difficult due to the existence of strong correlations which preclude\nthe development of a simple theory. Here, we take inspiration from liquid\ntheories for the $n$-particle angular correlation function to develop a\nformalism of random packings of hard particles from the bottom-up. A\nprogressive expansion into a shell of particles converges in the large layer\nlimit under a Kirkwood-like approximation of higher-order correlations. We\napply the formalism to hard disks and predict the density of two-dimensional\nrandom close packing (RCP), $\\phi_{\\rm rcp} = 0.85\\pm0.01$, and random loose\npacking (RLP), $\\phi_{\\rm rlp} = 0.67\\pm0.01$. Our theory also predicts a phase\ndiagram and angular correlation functions that are in good agreement with\nexperimental and numerical data.",
        "positive": "Crosslinked polymer chains with excluded volume: A new class of branched\n  polymers?: In this note microgels with and without excluded volume interactions are\nconsidered. Based on earlier exact computations on Gaussian mircogels, which\nare formed by self-crosslinking (with $M$ crosslinks) of polymer chains with\nchain length $N$ Flory type approximations are used to get first insight to\ntheir behavior in solution. It is shown that two different types of microgels\nexist: A special type of branched polymer whose size scales as $R \\propto\nN^{2/5} M^{-1/5}$, instead of $R \\propto N^{1/2}$. The second type are $c^*$ -\nmicrogels whose average mesh sizes $r$ are swollen and form self avoiding walks\nwith a scaling law of the form $r = a (N/M)^{3/5}$."
    },
    {
        "anchor": "Granular Matter and the Marginal Rigidity State: Model experiments are reported on the build-up of granular piles in two\ndimensions. These show that as the initial density of falling grains is\nincreased, the resulting pile has decreasing final density and its coordination\nnumber approaches the low value predicted for the theoretical marginal rigidity\nstate. This provides the first direct experimental evidence for this state of\ngranular matter. We trace the decrease in the coordination number to the\ndynamics within an advancing yield front between the consolidated pile and the\nfalling grains. We show that the front's size increases with initial density,\ndiverging as the marginal rigidity state is approached.",
        "positive": "Nonlinear effects in charge stabilized colloidal suspensions: Molecular Dynamics simulations are used to study the effective interactions\nin charged stabilized colloidal suspensions. For not too high macroion charges\nand sufficiently large screening, the concept of the potential of mean force is\nknown to work well. In the present work, we focus on highly charged macroions\nin the limit of low salt concentrations. Within this regime, nonlinear\ncorrections to the celebrated DLVO theory [B. Derjaguin and L. Landau, Acta\nPhysicochem. USSR {\\bf 14}, 633 (1941); E.J.W. Verwey and J.T.G. Overbeck, {\\em\nTheory of the Stability of Lyotropic Colloids} (Elsevier, Amsterdam, 1948)]\nhave to be considered. For non--bulklike systems, such as isolated pairs or\ntriples of macroions, we show, that nonlinear effects can become relevant,\nwhich cannot be described by the charge renormalization concept [S. Alexander\net al., J. Chem. Phys. {\\bf 80}, 5776 (1984)]. For an isolated pair of\nmacroions, we find an almost perfect qualitative agreement between our\nsimulation data and the primitive model. However, on a quantitative level,\nneither Debye-H\\\"uckel theory nor the charge renormalization concept can be\nconfirmed in detail. This seems mainly to be related to the fact, that for\nsmall ion concentrations, microionic layers can strongly overlap, whereas,\nsimultaneously, excluded volume effects are less important. In the case of\nisolated triples, where we compare between coaxial and triangular geometries,\nwe find attractive corrections to pairwise additivity in the limit of small\nmacroion separations and salt concentrations. These triplet interactions arise\nif all three microionic layers around the macroions exhibit a significant\noverlap. In contrast to the case of two isolated colloids, the charge\ndistribution around a macroion in a triple is found to be anisotropic."
    },
    {
        "anchor": "Thermal Fluctuations and Rubber Elasticity: The effects of thermal elastic fluctuations in rubber materials are examined.\nIt is shown that, due to an interplay with the incompressibility constraint,\nthese fluctuations qualitatively modify the large-deformation stress-strain\nrelation, compared to that of classical rubber elasticity. To leading order,\nthis mechanism provides a simple and generic explanation for the peak structure\nof Mooney-Rivlin stress-strain relation, and shows a good agreement with\nexperiments. It also leads to the prediction of a phonon correlation function\nthat depends on the external deformation.",
        "positive": "How water wets and self-hydrophilizes nanopatterns of physisorbed\n  hydrocarbons: Weakly bound, physisorbed hydrocarbons could in principle provide a similar\nwater-repellency as obtained by chemisorption of strongly bound hydrophobic\nmolecules at surfaces. Here we present experiments and computer simulations on\nthe wetting behavior of water on molecularly thin, self-assembled alkane\ncarpets of dotriacontane (n-C32H66 or C32) physisorbed on the hydrophilic\nnative oxide layer of silicon surfaces during dip-coating from a binary alkane\nsolution. By changing the dip-coating velocity we control the initial C32\nsurface coverage and achieve distinct film morphologies, encompassing\nhomogeneous coatings with self-organised nanopatterns that range from dendritic\nnano-islands to stripes. These patterns exhibit a good water wettability even\nthough the carpets are initially prepared with a high coverage of hydrophobic\nalkane molecules. Using in-liquid atomic force microscopy, along with molecular\ndynamics simulations, we trace this to a rearrangement of the alkane layers\nupon contact with water. This restructuring is correlated to the morphology of\nthe C32 coatings, i.e. their fractal dimension. Water molecules displace to a\nlarge extent the first adsorbed alkane monolayer and thereby reduce the\nhydrophobic C32 surface coverage. Thus, our experiments evidence that water\nmolecules can very effectively hydrophilize initially hydrophobic surfaces that\nconsist of weakly bound hydrocarbon carpets."
    },
    {
        "anchor": "The Rayleigh-Lamb wave propagation in dielectric elastomer layers\n  subjected to large deformations: The propagation of waves in soft dielectric elastomer layers is investigated.\nTo this end incremental motions superimposed on homogeneous finite deformations\ninduced by bias electric fields and pre-stretch are determined. First we\nexamine the case of mechanically traction-free layer, which is an extension of\nthe Rayleigh-Lamb problem in the purely elastic case. Two other loading\nconfigurations are accounted for too. Subsequently, numerical examples for the\ndispersion relations are evaluated for a dielectric solid governed by an\naugmented neo-Hookean strain energy. It is found that the the phase speeds and\nfrequencies strongly depend on the electric excitation and pre-stretch. These\nfindings lend themselves at the possibility of controlling the propagation\nvelocity as well as filtering particular frequencies with suitable choices of\nthe electric bias field.",
        "positive": "Evolution of interfaces and expansion in width: Interfaces in a model with a single, real nonconserved order parameter and\npurely dissipative evolution equation are considered. We show that a systematic\nperturbative approach, called the expansion in width and developed for curved\ndomain walls, can be generalized to the interfaces. Procedure for calculating\ncurvature corrections is described. We also derive formulas for local velocity\nand local surface tension of the interface. As an example, evolution of\nspherical interfaces is discussed, including an estimate of critical size of\nsmall droplets."
    },
    {
        "anchor": "Elastic Moduli in Nano-Size Samples of Amorphous Solids: System Size\n  Dependence: This Letter is motivated by some recent experiments on pan-cake shaped\nnano-samples of metallic glass that indicate a decline in the measured shear\nmodulus upon decreasing the sample radius. Similar measurements on crystalline\nsamples of the same dimensions showed a much more modest change. In this Letter\nwe offer a theory of this phenomenon; we argue that such results are\ngenerically expected for any amorphous solid, with the main effect being\nrelated to the increased contribution of surfaces with respect to bulk when the\nsamples get smaller. We employ exact relations between the shear modulus and\nthe eigenvalues of the system's Hessian matrix to explore the role of surface\nmodes in affecting the elastic moduli.",
        "positive": "Physico-chemical study of polymer mixtures formed by a polycation and a\n  zwitterionic copolymer in aqueous solution and upon adsorption onto\n  negatively charged surfaces: The adsorption of mixtures of charged polymers onto solid surfaces presents a\nbig interest in different technological and industrial fields, and in\nparticular, in cosmetics. This requires to deepen on the most fundamental\nphysico-chemical bases governing the deposition, which is generally correlated\nto the interactions occurring in solution. This work explores the interaction\nin solution of model polymer mixtures formed by a cationic homopolymer\n(poly(diallyl-dimethyl-ammonium chloride), PDADMAC) and a zwitterionic\ncopolymer (copolymer of acrylic acid, 3-Trimethylammonium propyl methacrylamide\nchloride and acrylamide, Merquat 2003), and the adsorption of such mixtures\nonto negatively charged surfaces. The analysis of the interactions occurring in\nsolution between both polymers performed using dynamic light scattering (DLS),\nelectrophoretic mobility and viscosity measurements, combined with the study of\nthe deposition of the layers of mixtures containing different weight fractions\nof each polymer using ellipsometry and quartz crystal microbalance with\ndissipation monitoring (QCM-D) has shown that the interpolymer complexes formed\nin solution, and their composition, governs the deposition onto the solid\nsurface and the tribological properties of the adsorbed layers as shown the\nSurface Force Apparatus (SFA) experiments, allowing for a control of the\nphysico-chemical properties and structure of the layers. Furthermore, the use\nof Self Consistent Mean Fields Calculations (SCF) confirms the picture obtained\nfrom the experimental studies of the adsorbed layers, providing a prediction of\nthe distribution of the polymer chains within the adsorbed layers. It is\nexpected that this study can help on the understanding of the correlations\nexisting between the behavior of future associations of innovative and\neco-sustainable polymers and their adsorption processes onto solid surface."
    },
    {
        "anchor": "Multiple Time-Scale Behaviour and Network Dynamics in Liquid Methanol: Canonical ensemble molecular dynamics simulations of liquid methanol, modeled\nusing a rigid-body, pair-additive potential, are used to compute static\ndistributions and temporal correlations of tagged molecule potential energies\nas a means of characterising the liquid state dynamics. The static distribution\nof tagged molecule potential energies shows a clear multimodal structure with\nthree distinct peaks, similar to those observed previously in water and liquid\nsilica. The multimodality is shown to originate from electrostatic effects, but\nnot from local, hydrogen-bond interactions. An interesting outcome of this\nstudy is the remarkable similarity in the tagged potential energy power spectra\nof methanol, water and silica, despite the differences in the underlying\ninteractions and the dimensionality of the network. All three liquids show a\ndistinct multiple time scale (MTS) regime with a 1/f dependence with a clear\npositive correlation between the scaling exponent alpha and the diffusivity.\nThe low-frequency limit of the MTS regime is determined by the frequency of\ncrossover to white noise behaviour which occurs at approximately 0.1 cm{-1} in\nthe case of methanol under standard temperature and pressure conditions. The\npower spectral regime above 200 cm{-1} in all three systems is dominated by\nresonances due to localised vibrations, such as librations. The correlation\nbetween $\\alpha$ and the diffusivity in all three liquids appears to be related\nto the strength of the coupling between the localised motions and the larger\nlength/time-scale network reorganizations. Thus the time scales associated with\nnetwork reorganization dynamics appear to be qualitatively similar in these\nsystems, despite the fact that water and silica both display diffusional\nanomalies but methanol does not.",
        "positive": "Depth resolved grazing incidence scattering from the solid-liquid\n  interface: We have applied small angle scattering in grazing incidence beam geometry on\na time-of-flight neutron instrument. Due to the broad wavelength distribution\nprovided for a specific incident beam angle the penetration depth of the\nneutron beam is varied over a broad range in a single measurement. The near\nsurface structure of polymer micelles close to silicon substrates with distinct\nsurface energy is resolved. It is observed that the very near-surface structure\nstrongly depends on the surface coating whereas further away from the surface\nbulk like ordering is found. A more pronounced ordering is found close to\nsurfaces with high surface energy."
    },
    {
        "anchor": "Periodic Instanton and Phase Transition in Quantum Tunneling of Spin\n  Systems: The quantum-classical transitions of the escape rates in a uniaxial spin\nmodel relevant to the molecular magnet Mn$_{12}$Ac and a biaxial anisotropic\nferromagnetic particle are investigated by applying the periodic instanton\nmethod. The effective free energies are expanded around the top of the\npotential barrier in analogy to Landau theory of phase transitions. We show\nthat the first-order transitions occur below the critical external magnetic\nfield $h_x = 1/4$ for the uniaxial spin model and beyond the critical\nanisotropy constant ratio $\\lambda = 1/2$ for the biaxial ferromagnetic grains,\nwhich are in good agreement with earlier works.",
        "positive": "Photonic gaps in cholesteric elastomers under deformation: Cholesteric liquid crystal elastomers have interesting and potentially very\nuseful photonic properties. In an ideal monodomain configuration of these\nmaterials, one finds a Bragg-reflection of light in a narrow wavelength range\nand a particular circular polarization. This is due to the periodic structure\nof the material along one dimension. In many practical cases, the cholesteric\nrubber possesses a sufficient degree of quenched disorder, which makes the\nselective reflection broadband. We investigate experimentally the problem of\nhow the transmittance of light is affected by mechanical deformation of the\nelastomer, and the relation to changes in liquid crystalline structure. We\nexplore a series of samples which have been synthesized with photonic stop-gaps\nacross the visible range. This allows us to compare results with detailed\ntheoretical predictions regarding the evolution of stop-gaps in cholesteric\nelastomers."
    },
    {
        "anchor": "Gas bubble evolution on microstructured silicon substrates: The formation, growth and detachment of gas bubbles on electrodes are\nomnipresent in electrolysis and other gas-producing chemical processes. To\nbetter understand their role in the mass transfer efficiency, we perform\nexperiments involving successive bubble nucleations from a predefined\nnucleation site which consists of a superhydrophobic pit on top of a\nmicromachined pillar. The experiments on bubble nucleation at these spots\npermit the comparison of mass transfer phenomena connected to electrolytically\ngenerated H$_2$ bubbles with the better-understood evolution of CO$_2$ bubbles\nin pressure-controlled supersaturated solutions. In both cases, bubbles grow in\na diffusion-dominated regime. For CO$_2$ bubbles, it is found that the growth\nrate coefficient of subsequent bubbles always decreases due to the effect of\ngas depletion. In contrast, during constant current electrolysis, the bubble\ngrowth rates are affected by the evolution of a boundary layer of dissolved\nH$_2$ gas near the flat electrode which competes with gas depletion. This\ncompetition results in three distinct regimes. Initially, the bubble growth\nslows down with each new bubble in the succession due to the dominant depletion\nof the newly-formed concentration boundary layer. In later stages, the growth\nrate increases due to a local increase of gas supersaturation caused by the\ncontinuous gas production and finally levels off to an approximate steady\ngrowth rate. The gas transport efficiency associated with the electrolytic\nbubble succession follows a similar trend in time. Finally, for both H$_2$ and\nCO$_2$ bubbles, detachment mostly occurs at smaller radii than theory predicts\nand at a surprisingly wide spread of sizes. A number of explanations are\nproposed, but the ultimate origin of the spreading of the results remains\nelusive.",
        "positive": "Loss of superfluidity in a Bose-Einstein condensate on an optical\n  lattice via a novel classical phase transition: We predict the loss of superfluidity in a Bose-Einstein condensate (BEC)\ntrapped in a combined optical and axially-symmetric harmonic potentials during\na resonant collective excitation initiated by a periodic modulation of the\natomic scattering length $a$, when the modulation frequency equals twice the\nradial trapping frequency or multiples thereof. This classical dynamical\ntransition is marked by a loss of superfluidity in the BEC and a subsequent\ndestruction of the interference pattern upon free expansion. Suggestion for\nfuture experiment is made."
    },
    {
        "anchor": "Lattice-Boltzmmann simulations of the sedimentation of charged disks: We report a series of Lattice-Boltzmann simulations of the sedimentation\nvelocity of charged disks. In these simulations, we explicitly account for the\nhydrodynamic and electrostatic forces on disks and on their electrical double\nlayer.\n  By comparing our results with those for spheres with equal surface and\ncharge, we can clarify the effect of the particle shape on the sedimentation\nprocess. We find that disks and spheres exhibit a different dependence of the\nsedimentation velocity on the Debye screening length. An analysis of the\nbehavior of highly charged disks (beyond the scope of the linearized\nPoisson-Boltzmann equation) shows that, in that regime, the charge dependence\nof the sedimentation velocity of disks and spheres is similar. This suggests\nthat, at high charge, the effective hydrodynamic shape of the disks becomes\nmore spherical.",
        "positive": "Anharmonic stacking in supercoiled DNA: Multistep denaturation in a short circular DNA molecule is analyzed by a\nmesoscopic Hamiltonian model which accounts for the helicoidal geometry.\nComputation of melting profiles by the path integral method suggests that\nstacking anharmonicity stabilizes the double helix against thermal disruption\nof the hydrogen bonds. Twisting is essential in the model to capture the\nimportance of nonlinear effects on the thermodynamical properties. In a ladder\nmodel with zero twist, anharmonic stacking scarcely affects the thermodynamics.\nModerately untwisted helices, with respect to the equilibrium conformation,\nshow an energetic advantage against the overtwisted ones. Accordingly\nmoderately untwisted helices better sustain local fluctuational openings and\nmake more unlikely the thermally driven complete strand separation."
    },
    {
        "anchor": "Determination of optimal effective interactions between amino acids in\n  globular proteins: An optimization technique is used to determine the pairwise interactions\nbetween amino acids in globular proteins. A numerical strategy is applied to a\nset of proteins for maximizing the native fold stability with respect to\nalternative structures obtained by gapless threading. The extracted parameters\nare shown to be very reliable for identifying the native states of proteins\n(unrelated to those in the training set) among thousands of conformations. The\nonly poor performers are proteins with heme groups and/or poor compactness\nwhose complexity cannot be captured by standard pairwise energy functionals.",
        "positive": "Drying by Cavitation and Poroelastic Relaxations in Porous Media with\n  Macroscopic Pores Connected by Nanoscale Throats: We investigate the drying dynamics of porous media with two pore diameters\nseparated by several orders of magnitude. Nanometer-sized pores at the edge of\nour samples prevent air entry, while drying proceeds by heterogeneous\nnucleation of vapor bubbles (cavitation) in the liquid in micrometer-sized\nvoids within the sample. We show that the dynamics of cavitation and drying are\nset by the interplay of the deterministic poroelastic mass transport in the\nporous medium and the stochastic nucleation process. Spatio-temporal patterns\nemerge in this unusual reaction-diffusion system, with temporal oscillations in\nthe drying rate and variable roughness of the drying front."
    },
    {
        "anchor": "Lattice Boltzmann simulations of contact line motion in a liquid-gas\n  system: We use a lattice Boltzmann algorithm for liquid-gas coexistence to\ninvestigate the steady state interface profile of a droplet held between two\nshearing walls. The algorithm solves the hydrodynamic equations of motion for\nthe system. Partial wetting at the walls is implemented to agree with Cahn\ntheory. This allows us to investigate the processes which lead to the motion of\nthe three-phase contact line. We confirm that the profiles are a function of\nthe capillary number and a finite size analysis shows the emergence of a\ndynamic contact angle, which can be defined in a region where the interfacial\ncurvature tends to zero.",
        "positive": "Some comments on the fracture of viscoelastic solids: Crack propagation in viscoelastic solids like rubber is of great practical\nimportance. Shrimali and Lopez-Pamies have proposed a new interesting approach\nfor the crack propagation in viscoelastic solids. We give comments on the\nvalidity of the theory and point out some effects not included in the theory."
    },
    {
        "anchor": "Towards a soft magnetoelastic twist actuator: Soft actuators allow to transform external stimuli to mechanical\ndeformations. Because of their deformational response to external magnetic\nfields, magnetic gels and elastomers represent ideal candidates for such tasks.\nMostly, linear magnetostrictive deformations, that is, elongations or\ncontractions along straight axes are discussed in this context. In contrast to\nthat, we here suggest to realize a twist actuator that responds by torsional\ndeformations around the axis of the applied magnetic field. For this purpose,\nwe theoretically investigate the overall mechanical response of a basic model\nsystem containing discrete magnetizable particles in a soft elastic matrix. Two\ndifferent types of discrete particle arrangements are used as starting\nconditions in the nonmagnetized state. These contain globally twisted\nanisotropic particle arrangements on the one hand, and groups of discrete\nhelical-like particle structures positioned side by side on the other hand.\nBesides the resulting twist upon magnetization, we also evaluate different\nother modes of deformation. Our analysis supports the construction of\nmagnetically orientable and actuatable torsional mixing devices in fluidic\napplications or other types of soft actuators that initiate relative rotations\nbetween different components.",
        "positive": "Stability of Two-Dimensional Soft Quasicrystals: The relative stability of two-dimensional soft quasicrystals is examined\nusing a recently developed projection method which provides a unified numerical\nframework to compute the free energy of periodic crystal and quasicrystals.\nAccurate free energies of numerous ordered phases, including dodecagonal,\ndecagonal and octagonal quasicrystals, are obtained for a simple model, i.e.\nthe Lifshitz-Petrich free energy functional, of soft quasicrystals with two\nlength-scales. The availability of the free energy allows us to construct phase\ndiagrams of the system, demonstrating that, for the Lifshitz-Petrich model, the\ndodecagonal and decagonal quasicrystals can become stable phases, whereas the\noctagonal quasicrystal stays as a metastable phase."
    },
    {
        "anchor": "The Osmotic Coefficient of Rod-like Polyelectrolytes: Computer\n  Simulation, Analytical Theory, and Experiment: The osmotic coefficient of solutions of rod-like polyelectrolytes is\nconsidered by comparing current theoretical treatments and simulations to\nrecent experimental data. The discussion is restricted to the case of\nmonovalent counterions and dilute, salt-free solutions. The classical\nPoisson-Boltzmann solution of the cell model correctly predicts a strong\ndecrease in the osmotic coefficient, but upon closer look systematically\noverestimates its value. The contribution of ion-ion-correlations are\nquantitatively studied by MD simulations and the recently proposed DHHC theory.\nHowever, our comparison with experimental data obtained on synthetic,\nstiff-chain polyelectrolytes shows that correlation effects can only partly\nexplain the discrepancy. A quantitative understanding thus requires theoretical\nefforts beyond the restricted primitive model of electrolytes.",
        "positive": "Microswimming with inertia: Microswimmers, especially in theoretical treatments, are generally taken to\nbe completely inertia-free, since inertial effects on their motion are\ntypically small and assuming their absence simplifies the problem considerably.\nYet in nature there is no discrete break between swimmers for which inertia is\nnegligibly small and for which it is detectable. Here we study a microswimming\nmodel for which the effect of inertia is calculated explicitly in the regime of\ntransition between the Stokesian and the non-Stokesian flow limits, which we\nterm the intermediate regime. The model in the inertialess limit is the\nbead-spring swimmer. We first show that in the intermediate regime a mechanical\nmicroswimmer exhibits damped inertial coasting like an underdamped harmonic\noscillator. We then calculate analytically the swimmer's velocity by including\na mass-acceleration term in the equations of motion which are otherwise based\non the Stokes flow. We show that this hybrid treatment combining aspects of\nunderdamped and overdamped dynamics provides an accurate description of the\nmotion in the intermediate regime, as verified here by comparison to\nsimulations using the lattice Boltzmann method, and is a significant\nimprovement over the results from the inertialess theory when either the mass\nof the swimmer or the forces driving its motion is/are large enough."
    },
    {
        "anchor": "Diffusion- and reaction-limited cluster aggregation revisited: We simulated irreversible aggregation of non-interacting particles and of\nparticles interacting via repulsive and attractive potentials explicitly\nimplementing the rotational diffusion of aggregating clusters. Our study\nconfirms that the attraction between particles influences neither the\naggregation mechanism nor the structure of the aggregates, which are identical\nto those of non-interacting particles. In contrast, repulsive particles form\nmore compact aggregates and their fractal dimension and aggregation times\nincrease with the decrease of the temperature. A comparison of the fractal\ndimensions obtained for non-rotating clusters of non-interacting particles and\nfor rotating clusters of repulsive particles provides an explanation for the\nconformity of the respective values obtained earlier in the well established\nmodel of diffusion-limited cluster aggregation neglecting rotational diffusion\nand in experiments on colloidal particles.",
        "positive": "Perspective: How to overcome dynamical density functional theory: We argue in favour of developing a comprehensive dynamical theory for\nrationalizing, predicting, designing, and machine learning nonequilibrium\nphenomena that occur in soft matter. To give guidance for navigating the\ntheoretical and practical challenges that lie ahead, we discuss and exemplify\nthe limitations of dynamical density functional theory. Instead of the implied\nadiabatic sequence of equilibrium states that this approach provides as a\nmakeshift for the true time evolution, we posit that the pending theoretical\ntasks lie in developing a systematic understanding of the dynamical functional\nrelationships that govern the genuine nonequilibrium physics. While static\ndensity functional theory gives a comprehensive account of the equilibrium\nproperties of many-body systems, we argue that power functional theory is the\nonly present contender to shed similar insights into nonequilibrium dynamics,\nincluding the recognition and implementation of exact sum rules that result\nfrom the Noether theorem. As~a~demonstration of the power functional point of\nview, we consider an idealized steady sedimentation flow of the\nthree-dimensional Lennard-Jones fluid and machine-learn the kinematic map from\nthe mean motion to the internal force field. The trained model is capable of\nboth predicting and designing the steady state dynamics universally for various\ntarget density modulations. This demonstrates the significant potential of\nusing such techniques in nonequilibrium many-body physics and overcomes both\nthe conceptual constraints of dynamical density functional theory as well as\nthe limited availability of its analytical functional approximations."
    },
    {
        "anchor": "Swimming eukaryotic microorganisms exhibit a universal speed\n  distribution: One approach to quantifying biological diversity consists of characterizing\nthe statistical distribution of specific properties of a taxonomic group or\nhabitat. Microorganisms living in fluid environments, and for whom motility is\nkey, exploit propulsion resulting from a rich variety of shapes, forms, and\nswimming strategies. Here, we explore the variability of swimming speed for\nunicellular eukaryotes based on published data. The data naturally partitions\ninto that from flagellates (with a small number of flagella) and from ciliates\n(with tens or more). Despite the morphological and size differences between\nthese groups, each of the two probability distributions of swimming speed are\naccurately represented by log-normal distributions, with good agreement holding\neven to fourth moments. Scaling of the distributions by a characteristic speed\nfor each data set leads to a collapse onto an apparently universal\ndistribution. These results suggest a universal way for ecological niches to be\npopulated by abundant microorganisms.",
        "positive": "Deformation of a free interface pierced by a tilted cylinder: We investigate the interaction between an infinite cylinder and a free\nfluid-fluid interface governed only by its surface tension. We study the\ndeformation of an initially flat interface when it is deformed by the presence\nof a cylindrical object, tilted at an arbitrary angle, that the interface\n\"totally wets\". Our simulations predict all significant quantities such as the\ninterface shape, the position of the contact line, and the force exerted by the\ninterface on the cylinder. These results are compared with an experimental\nstudy of the penetration of a soap film by a cylindrical liquid jet. This\ndynamic situation exhibits all the characteristics of a totally wetting\ninterface. We show that whatever the inclination, the force is always\nperpendicular to the plane of the interface, and its amplitude diverges as the\ninclination angle increases. Such results should bring new insights in both\nfluid and solid mechanics, from animal locomotion to surface\nmicro-processing.-processing."
    },
    {
        "anchor": "Solvation effects and contact angle saturation in electrowetting: Electrowetting of nanodrops is studied for aqueous electrolyte mixtures. We\nreport a new method for controlling the degree of deformation and minimum\nattainable contact angle by varying the difference of solvation strengths\nbetween the two solvents, which determines the ratio of ion concentrations.\nThis implies that the commonly observed saturation of the contact angle with\nthe applied electric field can be suppressed by increasing the solvation energy\ndifference, a finding of practical significance for micro and nanofluidics.\nSaturation is traced to be caused by the transfer of ions from the drop to the\nsurrounding medium. Furthermore, we derive an expression, based on the\nelectrokinetic equations, for the dependency of the drop's contact angle on the\nion concentration and the strength of the solvation potential in the absence of\nexternal electric fields.",
        "positive": "Microstructure of water sediments on hydrophilic surfaces: In the modern world, the focus of natural science research thought has\nshifted mainly to the molecular level, including the study of water. Water is\nconsidered as a mixture of interacting H2O molecules and their clusters based\non the data of molecular dynamics, neutron and X-ray scattering. In this case,\na huge layer of information is lost related to the composition of real water,\nits microstructure and behavior. In this work, we studied the structure and\ndynamics of water during its interaction with glass surfaces during drying\nusing optical microscopy. We observed a panoramic picture of a cascade of\ninterrelated phase transitions of distilled water and its microdispersed phase\n- sodium chloride microcrystals surrounded by a thick layer of hydrate liquid\ncrystal water. Incubation of a glass slide in water for 2 days was accompanied\nby adhesion of the microdisperse phase to the glass surface. During the free\nevaporation of distilled water from a Petri dish, erosion of hydration shells,\ndissolution of NaCl microcrystals, and further recrystallization with the\nformation of large monolithic crystals and traces of non-drying water were\nobserved. However, there are still questions that do not yet have clear\nanswers. The authors hope to continue research in collaboration with interested\ncolleagues."
    },
    {
        "anchor": "Free Energy Barrier for Electric Field Driven Polymer Entry into\n  Nanoscale Channels: Free energy barrier for entry of a charged polymer into a nanoscale channel\nby a driving electric field is studied theoretically and using molecular\ndynamics simulations. Dependence of the barrier height on the polymer length,\nthe driving field strength, and the channel entrance geometry is investigated.\nSqueezing effect of the electric field on the polymer before its entry to the\nchannel is taken into account. It is shown that lateral confinement of the\npolymer prior to its entry changes the polymer length dependence of the barrier\nheight noticeably. Our theory and simulation results are in good agreement and\nreasonably describe related experimental data.",
        "positive": "Criterion for noise-induced synchronization: application to colloidal\n  alignment: Colloidal bodies of irregular shape rotate as they descend under gravity in\nsolution. This rotational response provides a means of bringing a dispersion of\nidentical bodies into a synchronized rotation with the same orientation using\nprogrammed forcing. We use the notion of statistical entropy to derive bounds\non the rate of synchronization. These bounds apply generally to dynamical\nsystems with stable periodic motion with a phase $\\phi(t)$, when subjected to\nan impulsive perturbation. The impulse causes a change of phase expressible as\na phase map $\\psi(\\phi)$. We derive an upper limit on the average change of\nentropy $\\left<\\Delta H\\right>$ in terms of this phase map; when this limit is\nnegative, alignment must occur. For systems that have achieved a low entropy,\nthe $\\left<\\Delta H\\right>$ approaches this upper limit."
    },
    {
        "anchor": "Enhanced dielectrophoresis of nanocolloids by dimer formation: We investigate the dielectrophoretic motion of charge-neutral, polarizable\nnanocolloids through molecular dynamics simulations. Comparison to analytical\nresults derived for continuum systems shows that the discrete charge\ndistributions on the nanocolloids have a significant impact on their coupling\nto the external field. Aggregation of nanocolloids leads to enhanced\ndielectrophoretic transport, provided that increase in the dipole moment upon\naggregation can overcome the related increase in friction. The dimer\norientation and the exact structure of the nanocolloid charge distribution are\nshown to be important in the enhanced transport.",
        "positive": "Lattice models for granular-like velocity fields: Hydrodynamic limit: A recently introduced model describing -on a 1d lattice- the velocity field\nof a granular fluid is discussed in detail. The dynamics of the velocity field\noccurs through next-neighbours inelastic collisions which conserve momentum but\ndissipate energy. The dynamics can be described by a stochastic equation in\nfull phase space, or through the corresponding Master Equation for the time\nevolution of the probability distribution. In the hydrodynamic limit, equations\nfor the average velocity and temperature fields with fluctuating currents are\nderived, which are analogous to those of granular fluids when restricted to the\nshear modes. Therefore, the homogeneous cooling state, with its linear\ninstability, and other relevant regimes such as the uniform shear flow and the\nCouette flow states are described. The evolution in time and space of the\nsingle particle probability distribution, in all those regimes, is also\ndiscussed, showing that the local equilibrium is not valid in general. The\nnoise for the momentum and energy currents, which are correlated, are white and\nGaussian. The same is true for the noise of the energy sink, which is usually\nnegligible."
    },
    {
        "anchor": "Experimental observations of non-equilibrium distributions and\n  transitions in a 2D granular gas: A large number (~10,000) of uniform stainless steel balls comprising less\nthan one layer coverage on a vertically shaken plate provides a rich system for\nthe study of excited granular media. Viewed from above, the horizontal motion\nin the layer shows interesting collective behavior as a result of inelastic\nparticle-particle collisions. Clusters appear as localized fluctuations from\npurely random density distributions, as demonstrated by increased particle\ncorrelations. The clusters grow as the medium is \"cooled\" by reducing the rate\nof energy input. Further reduction of the energy input leads to the nucleation\nof a collapse: a close-packed crystal of particles at rest. High speed\nphotography allows for measurement of particle velocities between collisions.\nThe velocity distributions deviate strongly from a Maxwell distribution at low\naccelerations, and show approximately exponential tails, possibly due to an\nobserved cross-correlation between density and velocity fluctuations. When the\nlayer is confined with a lid, the velocity distributions at higher\naccelerations are non-Maxwellian and independent of the granular temperature.",
        "positive": "Effective one-component model of binary mixture: molecular arrest\n  induced by the spatially correlated stochastic dynamics: Spatially correlated noise (SCN), i.e. the thermal noise that affects\nneighbouring particles in a similar manner, is ubiquitous in soft matter\nsystems. In this work, we apply the over-damped SCN-driven Langevin equations\nas an effective, one-component model of the dynamics in dense binary mixtures.\nWe derive the thermodynamically consistent fluctuation-dissipation relation for\nSCN to show that it predicts the molecular arrest resembling the glass\ntransition, i.e. the critical slow-down of dynamics in the disordered phases.\nWe show that the mechanism of singular dissipation is embedded in the\ndissipation matrix, accompanying SCN. We are also able to identify the\ncharacteristic length of collective dissipation, which diverges at critical\npacking. This novel physical quantity conveniently describes the difference\nbetween the ergodic and non-ergodic dynamics. The model is fully analytically\nsolvable, one-dimensional and admits arbitrary interactions between the\nparticles. It qualitatively reproduces several different modes of arrested\ndisorder encountered in binary mixtures, including e.g. the re-entrant arrest.\nThe model can be effectively compared to the mode coupling theory."
    },
    {
        "anchor": "Clogging and Transport of Driven Particles in Asymmetric Funnel Arrays: We numerically examine the flow and clogging of particles driven through\nasymmetric funnel arrays when the commensurability ratio of the number of\nparticles per plaquette is varied. The particle-particle interactions are\nmodeled with a soft repulsive potential that could represent vortex flow in\ntype-II superconductors or driven charged colloids. The velocity-force curves\nfor driving in the easy flow direction of the funnels exhibit a single\ndepinning threshold; however, for driving in the hard flow direction, we find\nthat there can be both negative mobility where the velocity decreases with\nincreasing driving force as well as a reentrant pinning effect in which the\nparticles flow at low drives but become pinned at intermediate drives. This\nreentrant pinning is associated with a transition from smooth one-dimensional\nflow at low drives to a clogged state at higher drives that occurs when the\nparticles cluster in a small number of plaquettes and block the flow. When the\ndrive is further increased, particle rearrangements occur that cause the clog\nto break apart. We map out the regimes in which the pinned, flowing, and\nclogged states appear as a function of plaquette filling and drive. The clogged\nstates remain robust at finite temperatures but develop intermittent bursts of\nflow in which a clog temporarily breaks apart but quickly reforms.",
        "positive": "Stretching Homopolymers: Force induced stretching of polymers is important in a variety of contexts.\nWe have used theory and simulations to describe the response of homopolymers,\nwith $N$ monomers, to force ($f$) in good and poor solvents. In good solvents\nand for {{sufficiently large}} $N$ we show, in accord with scaling predictions,\nthat the mean extension along the $f$ axis $<Z>\\sim f$ for small $f$, and\n$<Z>\\sim f^{{2/3}}$ (the Pincus regime) for intermediate values of $f$. The\ntheoretical predictions for $\\la Z\\ra$ as a function of $f$ are in excellent\nagreement with simulations for N=100 and 1600. However, even with N=1600, the\nexpected Pincus regime is not observed due to the the breakdown of the\nassumptions in the blob picture for finite $N$. {{We predict the Pincus scaling\nin a good solvent will be observed for $N\\gtrsim 10^5$}}. The force-dependent\nstructure factors for a polymer in a poor solvent show that there are a\nhierarchy of structures, depending on the nature of the solvent. For a weakly\nhydrophobic polymer, various structures (ideal conformations, self-avoiding\nchains, globules, and rods) emerge on distinct length scales as $f$ is varied.\nA strongly hydrophobic polymer remains globular as long as $f$ is less than a\ncritical value $f_c$. Above $f_c$, an abrupt first order transition to a\nrod-like structure occurs. Our predictions can be tested using single molecule\nexperiments."
    },
    {
        "anchor": "Saddle-splay modulus of a particle-laden fluid interface: The scaled-particle theory equation of state for the two-dimensional\nhard-disk fluid on a curved surface is proposed and used to determine the\nsaddle-splay modulus of a particle-laden fluid interface. The resulting\ncontribution to saddle-splay modulus, which is caused by thermal motion of the\nadsorbed particles, is comparable in magnitude with the saddle-splay modulus of\na simple fluid interface.",
        "positive": "A Unified Model for Non-Fickian Diffusion and Anomalous Swelling of\n  Glassy Polymers: A sheet of glassy polymers placed in solvent shows swelling behaviors quite\ndifferent from that of soft polymers (rubbers and gels). (1) Non-Fickian\ndiffusion (called case II diffusion): As solvent permeates into the sample, a\nsharp front is created between the swollen part and the glassy part, and it\nmoves towards the center at constant speed. (2) Non-monotonous swelling: The\nthickness of the sample first increases and then decreases towards the\nequilibrium value. Here, we propose a unified theory for the swelling of glassy\npolymers. The theory regards the glassy polymers as a continuous mixture of\nviscoelastic network and solvent, where the relaxation time of polymer varies\nenormously depending on solvent concentration. We will show that this theory\nexplains the above two characteristics of such process in a simple and unified\nframework. The theory predicts how the permeation speed of solvent and the\ncharacteristic times of the swelling process depend on material parameters and\nexperimental conditions, which can be checked experimentally."
    },
    {
        "anchor": "Hydrodynamic and entropic effects on colloidal diffusion in corrugated\n  channels: In the absence of advection, confined diffusion characterizes transport in\nmany natural and artificial devices, such as ionic channels, zeolites, and\nnanopores. While extensive theoretical and numerical studies on this subject\nhave produced many important predictions, experimental verifications of the\npredictions are rare. Here, we experimentally measure colloidal diffusion times\nin microchannels with periodically varying width and contrast results with\npredictions from the Fick-Jacobs theory and Brownian dynamics simulation. While\nthe theory and simulation correctly predict the entropic effect of the varying\nchannel width, they fail to account for hydrodynamic effects, which include\nboth an overall decrease and a spatial variation of diffusivity in channels.\nNeglecting such hydrodynamic effects, the theory and simulation underestimate\nthe mean and standard deviation of first passage times by 40\\% in channels with\na neck width twice the particle diameter. We further show that the validity of\nthe Fick-Jakobs theory can be restored by reformulating it in terms of the\nexperimentally measured diffusivity. Our work thus demonstrates that\nhydrodynamic effects play a key role in diffusive transport through narrow\nchannels and should be included in theoretical and numerical models.",
        "positive": "Dielectric constant of water in the interface: We define the dielectric constant (susceptibility) that should enter the\nMaxwell boundary value problem when applied to microscopic dielectric\ninterfaces. The dielectric constant (susceptibility) of the interface is\ndefined by exact linear-response equations involving correlations of\nstatistically fluctuating interface polarization and the Coulomb interaction\nenergy of external charges with the dielectric. The theory is applied to the\ninterface between water and spherical solutes of altering size studied by\nmolecular dynamics (MD) simulations. The effective dielectric constant of\ninterfacial water is found to be significantly lower than its bulk value, and\nit also depends on the solute size. For TIP3P water used in MD simulations the\ninterface dielectric constant changes from 9 to 4 when the effective solute\nradius is increased from ~5 to 18 A."
    },
    {
        "anchor": "Elastic, thermal expansion, plastic and rheological processes - theory\n  and experiment: Rocks are important examples for solid materials where, in various\nengineering situations, elastic, thermal expansion, rheological/viscoelastic\nand plastic phenomena each may play a remarkable role. Nonequilibrium continuum\nthermodynamics provides a consistent way to describe all these aspects in a\nunified framework. This we present here in a formulation where the kinematic\nquantities allow arbitrary nonzero initial (e.g., in situ) stresses and such\ninitial configurations which - as a consequence of thermal or remanent stresses\n- do not satisfy the kinematic compatibility condition. The various\ncharacteristic effects accounted by the obtained theory are illustrated via\nexperimental results where loaded solid samples undergo elastic, thermal\nexpansion and plastic deformation and exhibit rheological behaviour. From the\nexperimental data, the rheological coefficients are determined, and the\nmeasured temperature changes are also explained by the theory.",
        "positive": "Symmetry Based Properties of the Transition Metal Dichalcogenide\n  Nanotubes: The full geometrical symmetry groups (the line groups) of the monolayered,\n2Hb and 3R polytypes of the inorganic MoS2 and WS2 micro- and nanotubes of\narbitrary chirality are found. This is used to find the coordinates of the\nrepresentative atoms sufficient to determine completely geometrical structure\nof tubes. Then some physical properties which can be deduced from the symmetry\nare discussed: electron band degeneracies, selection rules, general forms of\nthe second rank tensors and potentials, phonon spectra."
    },
    {
        "anchor": "Tension and stiffness of the hard sphere crystal-fluid interface: A combination of fundamental measure density functional theory and Monte\nCarlo computer simulation is used to determine the orientation-resolved\ninterfacial tension and stiffness for the equilibrium hard-sphere crystal-fluid\ninterface. Microscopic density functional theory is in quantitative agreement\nwith simulations and predicts a tension of 0.66 kT/\\sigma^2 with a small\nanisotropy of about 0.025 kT and stiffnesses with e.g. 0.53 kT/\\sigma^2 for the\n(001) orientation and 1.03 kT/\\sigma^2 for the (111) orientation. Here kT is\ndenoting the thermal energy and \\sigma the hard sphere diameter. We compare our\nresults with existing experimental findings.",
        "positive": "Nonlinear Correction to the Euler Buckling Formula for Compressed\n  Cylinders with Guided-Guided End Conditions: Euler's celebrated buckling formula gives the critical load $N$ for the\nbuckling of a slender cylindrical column with radius $B$ and length $L$ as \\[ N\n/ (\\pi^3 B^2) = (E/4)(B/L)^2, \\] where $E$ is Young's modulus. Its derivation\nrelies on the assumptions that linear elasticity applies to this problem, and\nthat the slenderness $(B/L)$ is an infinitesimal quantity. Here we ask the\nfollowing question: What is the first nonlinear correction in the right\nhand-side of this equation when terms up to $(B/L)^4$ are kept? To answer this\nquestion, we specialize the exact solution of incremental non-linear elasticity\nfor the homogeneous compression of a thick compressible cylinder with\nlubricated ends to the theory of third-order elasticity. In particular, we\nhighlight the way second- and third-order constants ---including Poisson's\nratio--- all appear in the coefficient of $(B/L)^4$."
    },
    {
        "anchor": "Large scale Micro-Photometry for high resolution pH-characterization\n  during electro-osmotic pumping and modular micro-swimming: Micro-fluidic pumps as well as artificial micro-swimmers are conveniently\nrealized exploiting phoretic solvent flows based on local gradients of\ntemperature, electrolyte concentration or pH. We here present a facile\nmicro-photometric method for monitoring pH gradients and demonstrate its\nperformance and scope on different experimental situations including an\nelectro-osmotic pump and modular micro-swimmers assembled from ion exchange\nresin beads and polystyrene colloids. In combination with the present\nmicroscope and DSLR camera our method offers a 2 \\mu m spatial resolution at\nvideo frame rate over a field of view of 3920x2602 \\mu m^2. Under optimal\nconditions we achieve a pH-resolution of 0.05 with about equal contributions\nfrom statistical and systematical uncertainties. Our quantitative\nmicro-photometric characterization of pH gradients which develop in time and\nreach out several mm is anticipated to provide valuable input for reliable\nmodeling and simulations of a large variety of complex flow situations\ninvolving pH-gradients including artificial micro-swimmers, microfluidic\npumping or even electro-convection.",
        "positive": "From Effective Interactions Extracted Using Hi-C Data to Chromosome\n  Structures in Conventional and Inverted Nuclei: Contact probabilities between loci, separated by arbitrary genomic distance,\nfor a number of cell types have been reported using genome-wide chromosome\nconformation capture (Hi-C) experiments. How to extract the effective\ninteraction energies between active euchromatin (A) and inactive\nheterochromatin (B) directly from the experimental data, without an underlying\npolymer model, is unsolved. Here, we first calculate the pairwise effective\ninteraction energies (A-A, B-B, or A-B) for interphase chromosomes based on\nHi-C data by using the concept of Statistical Potential (SP), which assumes\nthat the interaction energy between two loci is proportional to the logarithm\nof the frequency with which they interact. Polymer simulations, using the\nextracted interaction energy values $\\textit{without any parameter}$, reproduce\nthe segregation between A and B type loci (compartments), and the emergence of\ntopologically associating domains (TADs), features that are prominent in the\nHi-C data for interphase chromosomes. Remarkably, the values of the SP\nautomatically satisfy the Flory-Huggins phase separation criterion for all the\nchromosomes, which explains the mechanism of compartment formation in\ninterphase chromosomes. Strikingly, simulations using the SP that accounts for\npericentromeric constitutive heterochromatin (C-type), show hierarchical\nstructuring with the high density of C-type loci in the nuclear center,\nfollowed by localization of the B type loci, with euchromatin being confined to\nthe nuclear periphery, which differs from the expected nuclear organization of\ninterphase chromosomes, but is in accord with the imaging data of the inverted\nnuclei found in photoreceptor rods in nocturnal mammals. The proposed parameter\nfree method and applications show that compartment formation in conventional\nand inverted nuclei is best explained by the inequality between the effective\ninteraction energies."
    },
    {
        "anchor": "Shear-thickening in presence of adhesive contact forces: the singularity\n  of cornstarch: A number of dense particle suspensions experience a dramatic increase in\nviscosity with the shear stress, up to a solid-like response. This\nshear-thickening process is understood as a transition under flow of the nature\nof the contacts, from lubricated to frictional, between initially repellent\nparticles. Most systems are now assumed to fit in with this scenario, which is\nquestionable. Using an in-house pressure sensor array, we provide a\nspatio-temporal map of the normal stresses in the flows of two shear-thickening\nfluids: a stabilised calcium carbonate suspension, known to fit in with the\nstandard scenario, and a cornstarch suspension, which spectacular thickening\nbehavior remains poorly understood. We evidence in cornstarch a unique, stable\nheterogeneous structure, which moves in the velocity direction and does not\nappear in calcium carbonate. Its nature changes from a stress wave to a rolling\nsolid jammed aggregate at high solid fraction and small gap width. The modeling\nof these heterogenities points to an adhesive force between cornstarch\nparticles at high stress, also evidenced in microscopic measurements.\nCornstarch being also attractive at low stress, it stands out of the classical\nshear-thickening frame, and might be part of a larger family of adhesive and\nattractive shear-thickening fluids.",
        "positive": "Low-energy non-linear excitations in sphere packings: We study theoretically and numerically how hard frictionless particles in\nrandom packings can rearrange. We demonstrate the existence of two distinct\nunstable non-linear modes of rearrangement, both associated with the opening\nand the closing of contacts. Mode one, whose density is characterized by some\nexponent {\\theta}', corresponds to motions of particles extending throughout\nthe entire system. Mode two, whose density is characterized by an exponent\n{\\theta} != {\\theta}', corresponds to the local buckling of a few particles.\nMode one is shown to yield at a much higher rate than mode two when a stress is\napplied. We show that the distribution of contact forces follows P(f)\nf^{min({\\theta}',{\\theta})}, and that imposing that the packing cannot be\ndensified further leads to the bounds {\\gamma} >= 1/(2+{\\theta}') and {\\gamma}\n>= (1-{\\theta})/2, where {\\gamma} characterizes the singularity of the pair\ndistribution function g(r) at contact. These results extend the theoretical\nanalysis of [M. Wyart, Phys. Rev. Lett 109, 125502 (2012)] where the existence\nof mode two was not considered. We perform numerics that support that these\nbounds are saturated with {\\gamma} \\approx 0.38, {\\theta} \\approx 0.17 and\n{\\theta}' \\approx 0.44. We measure systematically the stability of all such\nmodes in packings, and confirm their marginal stability. The principle of\nmarginal stability thus allows to make clearcut predictions on the ensemble of\nconfigurations visited in these out-of-equilibrium systems, and on the contact\nforces and pair distribution functions. It also reveals the excitations that\nneed to be included in a description of plasticity or flow near jamming, and\nsuggests a new path to study two-level systems and soft spots in simple\namorphous solids of repulsive particles."
    },
    {
        "anchor": "Mesoscopic lattice Boltzmann modeling of flowing soft systems: A mesoscopic multi-component lattice Boltzmann model with short-range\nrepulsion between different species and short/mid-ranged attractive/repulsive\ninteractions between like-molecules is introduced. The interplay between these\ncomposite interactions gives rise to a rich configurational dynamics of the\ndensity field, exhibiting many features of disordered liquid dispersions\n(micro-emulsions) and soft-glassy materials, such as long-time relaxation due\nto caging effects, anomalous enhanced viscosity, ageing effects under moderate\nshear and flow above a critical shear rate.",
        "positive": "Asymptotic self-restabilization of a continuous elastic structure: A challenge in soft robotics and soft actuation is the determination of an\nelastic system which spontaneously recovers its trivial path during\npostcritical deformation after a bifurcation. The interest in this behaviour is\nthat a displacement component spontaneously cycles around a null value, thus\nproducing a cyclic soft mechanism. An example of such a system is theoretically\nproven through the solution of the Elastica and a stability analysis based on\ndynamic perturbations. It is shown that the asymptotic self-restabilization is\ndriven by the development of a configurational force, of similar nature to the\nPeach-Koehler interaction between dislocations in crystals, which is derived\nfrom the principle of least action. A proof-of-concept prototype of the\ndiscovered elastic system is designed, realized, and tested, showing that this\ninnovative behaviour can be obtained in a real mechanical apparatus."
    },
    {
        "anchor": "Supramolecular assemblies in active motor-filament systems: micelles,\n  bilayers, and foams: Active matter systems evade the constraints of thermal equilibrium, leading\nto the emergence of intriguing collective behavior. A paradigmatic example is\ngiven by motor-filament mixtures, where the motion of motor proteins drives\nalignment and sliding interactions between filaments and their\nself-organization into macroscopic structures. After defining a microscopic\nmodel for these systems, we derive continuum equations, exhibiting the\nformation of active supramolecular assemblies such as micelles, bilayers and\nfoams. The transition between these structures is driven by a branching\ninstability, which destabilizes the orientational order within the micelles,\nleading to the growth of bilayers at high microtubule densities. Additionally,\nwe identify a fingering instability, modulating the shape of the micelle\ninterface at high motor densities. We study the role of various mechanisms in\nthese two instabilities, such as contractility, active splay, and anchoring,\nallowing for generalization beyond the system considered here.",
        "positive": "Energy Transport in Glasses: The temperature dependence of the thermal conductivity is linked to the\nnature of the energy transport at a frequency omega, which is quantified by\nthermal diffusivity d(omega). Here we study d(omega) for a poorly annealed\nglass and a highly stable glass prepared using the swap Monte Carlo algorithm.\nTo calculate d(omega), we excite wave packets and find that the energy moves\ndiffusively for high frequencies up to a maximum frequency, beyond which the\nenergy stays localized. At intermediate frequencies, we find a linear increase\nof the square of the width of the wave packet with time, which allows for a\nrobust calculation of d(omega), but the wave packet is no longer well described\nby a Gaussian as for high frequencies. In this intermediate regime, there is a\ntransition from a nearly frequency independent thermal diffusivity at high\nfrequencies to d(omega) ~ omega^(-4) at low frequencies. For low frequencies\nthe sound waves are responsible for energy transport and the energy moves\nballistically. The low frequency behavior can be predicted using sound\nattenuation coefficients."
    },
    {
        "anchor": "Polarization dependence of photo-mechanical behavior of monodomain\n  liquid crystal polymeric materials: Polarization dependence of opto-mechanical behavior of monodomain\nphotochromic glassy liquid crystal (LC) polymers under polarized ultraviolet\nlight (PUV) is studied. Trans-cis photo-isomerization is generally known to be\nmost intense at 'parallel illumination' (polarization parallel to LC director),\nas light-medium interactions are active when polarization aligns with\ntrainsition dipole moment. We show that at parallel illumination though cis\nisomers are converted from trans the most near surface, they can be the least\nbelow certain light propagation depth. Membrane force, an average effect of\ntrans-cis conversion over propagation depths, shows a monotonic polarization\ndependence, i.e. maximum at parallel illumination, which agrees well with\nexperiment [1]. However, under strong illumination, cis\nfraction/photo-contraction distribution through depths shows deep penetration,\nswitching over the polarization dependence in photo-moment, which is related to\nphoto-contraction gradient ---- photo-moment can be maximum at 'perpendicular\nillumination' (polarization perpendicular to director) under strong light. We\ngive both intuitive explanation and analytical demonstration in thin strip\nlimit for the switchover.",
        "positive": "The conformational phase diagram of charged polymers in the presence of\n  attractive bridging crowders: Using extensive molecular dynamics simulations, we obtain the conformational\nphase diagram of a charged polymer in the presence of oppositely charged\ncounterions and neutral attractive crowders for monovalent, divalent and\ntrivalent counterion valencies. We demonstrate that the charged polymer can\nexist in three phases: (1) an extended phase for low charge densities and weak\npolymer-crowder attractive interactions ($CE$), (2) a collapsed phase for high\ncharge densities and weak polymer-crowder attractive interactions, primarily\ndriven by counterion condensation ($CCI$), and (3) a collapsed phase for strong\npolymer-crowder attractive interactions, irrespective of the charge density,\ndriven by crowders acting as bridges or crosslinks ($CCB$). Importantly, the\nsimulations reveal that the interaction with crowders can induce collapse,\ndespite the presence of strong repulsive electrostatic interactions, and can\nreplace condensed counterions to facilitate a direct transition from the $CCI$\nand $CE$ phases to the $CCB$ phase."
    },
    {
        "anchor": "Non-equilibrium systems have steady-state distributions and non-steady\n  dynamics: We search for steady states in a class of fluctuating and driven physical\nsystems that exhibit sustained currents. We find that the physical concept of a\nsteady state, well known for systems at equilibrium, must be generalised to\ndescribe such systems. In these, the generalisation of a steady state is\nassociated with a stationary probability density of micro-states and a\ndeterministic dynamical system whose trajectories the system follows on\naverage. These trajectories are a manifestation of non-stationary macroscopic\ncurrents observed in these systems. We determine precise conditions for the\nsteady state to exist as well as the requirements for it to be stable. We\nillustrate this with some examples.",
        "positive": "Buckling of chiral rods due to coupled axial and rotational growth: We present a growth model for special Cosserat rods that allows for induced\nrotation of cross-sections. The growth law considers two controls, one for\nlengthwise growth and other for rotations. This is explored in greater detail\nfor straight rods with helical and hemitropic material symmetries by\nintroduction of a symmetry preserving growth to account for the microstructure.\nThe example of a guided-guided rod possessing a chiral microstructure is\nconsidered to study its deformation due to growth. We show the occurrence of\ngrowth induced out-of-plane buckling in such rods."
    },
    {
        "anchor": "Active Particles in Explicit Solvent: Dynamics of clustering for\n  alignment interaction: We study dynamics of clustering in systems containing active particles that\nare immersed in an explicit solvent. For this purpose we have adopted a hybrid\nsimulation method, consisting of molecular dynamics and multi-particle\ncollision dynamics. In our model, overlap-avoiding passive interaction of an\nactive particle with another active particle or a solvent particle has been\ntaken care of via variants of Lennard-Jones potential. Dynamic interaction\namong the active particles has been incorporated via the Vicsek-like\nself-propulsion that facilitates clustering. We quantify the effects of\nactivity and importance of hydrodynamics on the dynamics of clustering via\nvariations of relevant system parameters. We work with low overall density of\nactive particles. For this the morphology consists of disconnected clusters,\nthe mechanism of growth switching among particle diffusion, diffusive\ncoalescence and ballistic aggregation, depending upon the presence or absence\nof active and hydrodynamic interactions. Corresponding growth laws have been\nquantified and discussed in the background of appropriate theoretical pictures.\nOur results suggest that multi-particle collision dynamics is an effective\nmethod for investigation of hydrodynamic phenomena even in active matter\nsystems.",
        "positive": "Ligand-Mediated Interactions between Nanoscale Surfaces Depend\n  Sensitively and Nonlinearly on Temperature, Facet Dimensions, and Ligand\n  Coverage: Nanoparticles are often covered in ligand monolayers, which can undergo a\ntemperature-dependent order-disorder transition that switches the\nparticle-particle interaction from repulsive to attractive in solution. In this\nwork, we examine how changes in the ligand surface coverage and facet\ndimensions affect the ordering of ligands, the arrangement of nearby solvent\nmolecules, and the interaction between ligand monolayers on different\nparticles. In particular, we consider the case of strongly bound octadecyl\nligands on the (100) facet of CdS in the presence of an explicit n-hexane\nsolvent. Depending on the facet dimensions and surface coverage, we observe\nthree distinct ordered states that differ in how the ligands are packed\ntogether, and which affect the thickness of the ligand shell and the structure\nof the ligand-solvent interface. The temperature dependence of the\norder-disorder transition also broadens and shifts to lower temperature in a\nnonlinear manner as the nanoscale is approached from above. We find that\nligands on nanoscale facets can behave very similarly to those on macroscopic\nsurfaces in solution, and that some facet dimensions affect the ligand\nalignment more strongly than others. As the ligands order, the interaction\nbetween opposing monolayers becomes attractive, even well below full surface\ncoverage. The strength of attraction per unit surface area is strongly affected\nby ligand coverage, but only weakly by facet width. Conversely, we find that\nbringing two monolayers together just above the order-disorder transition\ntemperature can induce ordering and attraction."
    },
    {
        "anchor": "Switchable Wetting of Stimulus Responsive Polymer Brushes by Lipid\n  Vesicles: Experiments and Simulations: We grafted polyacrylic acid brushes containing cysteine side chains at a\ndefined surface density on planar lipid membranes. Specular X-ray reflectivity\ndata indicated that the addition of Cd2+ ions induces the compaction of the\npolymer brush layer and modulates the adhesion of lipid vesicles. The critical\nthreshold level inducing the switch from non-wetting to partial wetting state,\n[Cd2+] = 0.25 mM, was determined by microinterferometry. The interactions\nbetween vesicles and brushes were evaluated by height fluctuations of the\nmembrane in contact with brushes and the shape of vesicles near the surface. To\nanalyze these experiments, we have studied adhesion of axially symmetric\nvesicles for finite-range membrane-substrate interaction and buoyancy through\nsimulations. We found that the local transversality condition that relates the\nmaximal curvature at the edge of the adhesion zone to the adhesion strength\nremains rather accurate. Thus, although it is not experimentally possible to\nprepare vesicles at zero buoyancy, we can use the transversality condition to\nestimate the adhesion strength. However, the adhesion diagram is significantly\nmodified by a finite range of membrane-substrate interaction and buoyancy. For\ndownward buoyancy, vesicles merely sediment onto the substrate and there is no\nmean-field adhesion transition. For upward buoyancy, adhered vesicles are\nmetastable at best. Thus, a mean-field adhesion transition can only occur at\nvanishing buoyancy. Only for zero-range membrane-substrate interaction does a\nsecond-order adhesion transition occur at finite interaction strength. For any\nfinite-range interaction, the transition occurs when the membrane-substrate\ninteraction changes from repulsive to attractive. We present a adhesion diagram\nas a function of adhesion strength and buoyancy and compare the adhesion\nbehavior of vesicles to the wetting behavior of droplets of liquids.",
        "positive": "Repulsive interactions of eco-corona covered microplastic particles\n  quantitatively follow modelling of polymer brushes: Environmental fate and toxicity of microplastic particles is dominated by\ntheir surface properties. In the environment an adsorbed layer of biomolecules\nand natural organic matter forms the so-called eco-corona. A quantitative\ndescription of how this eco-corona changes the particles' colloidal\ninteractions is still missing. Here, we demonstrate with colloidal probe-atomic\nforce microscopy that the formation of the eco-corona on microplastic particles\nintroduces a soft film on the surface which changes the mechanical behaviour.\nWe measure single particle-particle interactions and find a pronounced increase\nof long-range repulsive interactions upon eco-corona formation. These\nforce-distance characteristics follow well the polymer brush model by Alexander\nand de Gennes. We further compare the obtained fitting parameters to known\nsystems like polyelectrolyte multilayers and propose these as a model system\nfor the eco-corona. The foundation of the eco-corona interacting like a polymer\nbrush with its surrounding may help understand microplastic transport and\naggregation in the environment."
    },
    {
        "anchor": "Dramatic changes in DNA Conductance with stretching: Structural\n  Polymorphism at a critical extension: In order to interpret recent experimental studies of the dependence of\nconductance of ds-DNA as the DNA is pulled from the 3'end1-3'end2 ends, which\nfind a sharp conductance jump for a very short (4.5 %) stretching length, we\ncarried out multiscale modeling, to predict the conductance of dsDNA as it is\nmechanically stretched to promote various structural polymorphisms. We\ncalculate the current along the stretched DNA using a combination of molecular\ndynamics simulations, non-equilibrium pulling simulations, quantum mechanics\ncalculations, and kinetic Monte Carlo simulations. For 5'end1-5'end2\nattachments we find an abrupt jump in the current within a very short\nstretching length (6 $ \\AA $ or 17 %) leading to a melted DNA state. In\ncontrast, for 3'end1-3'end2 pulling it takes almost 32$ \\AA $ (84 %) of\nstretching to cause a similar jump in the current. Thus, we demonstrate that\ncharge transport in DNA can occur over stretching lengths of several\nnanometers. We find that this unexpected behaviour in the B to S conformational\nDNA transition arises from highly inclined base pair geometries that result\nfrom this pulling protocol. We find that the dramatically different conductance\nbehaviors for two different pulling protocols arise from the nature of how\nhydrogen bonds of DNA base pairs break.",
        "positive": "Use of Superparamagnetic Nanoparticle/Block Copolymer Electrostatic\n  Complexes as Contrast Agents in Magnetic Resonance Imaging: During the past years we have investigated the complexation between\nnanocolloids and oppositely charged polymers. The nanocolloids examined were\nionic surfactant micelles and inorganic oxide nanoparticles. For the polymers,\nwe used homopolyelectrolytes and block copolymers with linear and comb\narchitectures. In general, the attractive interactions between oppositely\ncharged species are strong and as such, the simple mixing of solutions\ncontaining dispersed constituents yield to a precipitation, or to a phase\nseparation. We have developed means to control the electrostatically-driven\nattractions and to preserve the stability of the mixed solution. With these\napproaches, we designed novel core-shell nanostructures, e.g. as those obtained\nwith polymers and iron oxide superparamagnetic nanoparticles. In this\npresentation, we show that electrostatic complexation can be used to tailor new\nfunctionalized nanoparticles and we provide examples related to biomedical\napplications in the domain of contrast agents for Magnetic Resonance Imaging."
    },
    {
        "anchor": "Angular structure factor of the hexatic-B liquid crystals: bridging\n  theory and experiment: We report results from X-ray scattering studies of the angular structure\nfactor of liquid crystal hexatic-B films. According to the sixfold rotational\nsymmetry of the hexatic-B phase, its characteristic scattering splits into six\nreflections. The shape of the radial and angular cross-sections of these\nreflections and their temperature evolution are analyzed. We find that over a\nwide temperature range of the hexatic-B phase existence the angular profiles of\nthe in-plane X-ray scattering are well fitted by the Voigt function, which is a\nconvolution of the Gaussian and Lorentzian functions. This result is supported\nby the known theoretical considerations of the hexatic structure factor below\nthe smectic-hexatic phase transition temperture. Similar predictions for the\nangular shape of the hexatic peak in the vicinity of the smectic-hexatic phase\ntransition temperature follow from the multicritical scaling theory of the\nhexatic-B phase in three dimensions. We find that the specific shape of the\nhexatic structure factor can be explained by the interplay of two distinct\ncontributions to the free energy of the system, a liquid-like density term and\na coupling term between the bond-orientational order and short-range density\nfluctuations.",
        "positive": "Metastability as a mechanism for yielding in amorphous solids under\n  cyclic shear: We consider the yielding behavior of amorphous solids under cyclic shear\ndeformation and show that it can be mapped into a random walk in a confining\npotential with an absorbing boundary. The resulting dynamics is governed by the\nfirst passage time into the absorbing state and suffices to capture the\nessential qualitative features recently observed in atomistic simulations of\namorphous solids. Our results provide insight into the mechanism underlying\nyielding and its robustness. When the possibility of activated escape from\nabsorbing states is added, it leads to a unique determination of a threshold\nenergy and yield strain, suggesting thereby an appealing approach to\nunderstanding fatigue failure."
    },
    {
        "anchor": "Radio frequency spectroscopy and the pairing gap in trapped Fermi gases: We present a theoretical interpretation of radio-frequency (RF) pairing gap\nexperiments in trapped atomic Fermi gases, over the entire range of the BCS-BEC\ncrossover, for temperatures above and below $T_c$. Our calculated RF excitation\nspectra, as well as the density profiles on which they are based, are in\nsemi-quantitative agreement with experiment. We provide a detailed analysis of\nthe physical origin of the two different peak features seen in RF spectra, one\nassociated with nearly free atoms at the edge of the trap, and the other with\n(quasi-)bound fermion pairs.",
        "positive": "Ferromagnetic Liquid Thin Films Under Applied Field: Theoretical calculations, computer simulations and experiments indicate the\npossible existence of a ferromagnetic liquid state, although definitive\nexperimental evidence is lacking. Should such a state exist, demagnetization\neffects would force a nontrivial magnetization texture. Since liquid droplets\nare deformable, the droplet shape is coupled with the magnetization texture. In\na thin-film geometry in zero applied field, the droplet has a circular shape\nand a rotating magnetization texture with a point vortex at the center. We\ncalculate the elongation and magnetization texture of such ferromagnetic thin\nfilm liquid droplet confined between two parallel plates under a weak applied\nmagnetic field. The vortex stretches into a domain wall and exchange forces\nbreak the reflection symmetry. This behavior contrasts qualitatively and\nquantitatively with the elongation of paramagnetic thin films."
    },
    {
        "anchor": "Generalized Langevin equation with shear flow and its\n  fluctuation-dissipation theorems derived from a Caldeira-Leggett Hamiltonian: We provide a first-principles derivation of the Langevin equation with shear\nflow and its corresponding fluctuation-dissipation theorems. Shear flow of\nsimple fluids has been widely investigated by numerical simulations. Most\nstudies postulate a Markovian Langevin equation with a simple shear drag term\n\\`a la Stokes. However, this choice has never been justified from first\nprinciples. We start from a particle-bath system described by a classical\nCaldeira-Leggett Hamiltonian modified by adding a term proportional to the\nstrain-rate tensor according to Hoover's DOLLS method, and we derive a\ngeneralized Langevin equation for the sheared system. We then compute,\nanalytically, the noise time-correlation functions in different regimes. Based\non the intensity of the shear-rate, we can distinguish between\nclose-to-equilibrium and far-from-equilibrium states. According to the results\npresented here, the standard, simple and Markovian form of the Langevin\nequation with shear flow postulated in the literature is valid only in the\nlimit of extremely weak shear rates compared to the effective vibrational\ntemperature of the bath. For even marginally higher shear rates, the\n(generalized) Langevin equation is strongly non-Markovian and non-trivial\nfluctuation-dissipation theorems are derived.",
        "positive": "The nematic-isotropic phase transition in linear fused hard-sphere chain\n  fluids: We present a modification of the generalized Flory dimer theory to\ninvestigate the nematic (N) to isotropic (I) phase transition in chain fluids.\nWe focus on rigid linear fused hard-sphere (LFHS) chain molecules in this\nstudy. A generalized density functional theory is developed, which involves an\nangular weighting of the dimer reference fluid as suggested by decoupling\ntheory, to accommodate nematic ordering in the system. A key ingredient of this\ntheory is the calculation of the exact excluded volume for a pair of molecules\nin an arbitrary relative orientation, which extends the recent work by\nWilliamson and Jackson for linear tangent hard-sphere chain molecules to the\ncase of linear fused hard-sphere chains with arbitrary intramolecular\nbondlength. The present results for the N-I transition are compared with\nprevious theories and with computer simulations. In comparison with previous\nstudies, the results show much better agreement with simulations for both the\ncoexistence densities and the nematic order parameter at the transition."
    },
    {
        "anchor": "Structure and aggregation of colloids immersed in critical solvents: We consider an ensemble of spherical colloidal particles immersed in a\nnear-critical solvent such as a binary liquid mixture close to its critical\ndemixing point. The emerging long-ranged fluctuations of the corresponding\norder parameter of the solvent drive the divergence of the correlation length.\nSpatial confinements of these critical fluctuations by colloidal solute\nparticles, acting as cavities in the fluctuating medium, restrict and modify\nthe fluctuation spectrum in a way which depends on their relative\nconfiguration. This results in effective, so-called critical Casimir forces\n(CCFs) acting on the confining surfaces. Using the available knowledge about\nCCFs we study the structure and stability of such colloidal suspensions by\nemploying an approach in terms of effective, one-component colloidal systems.\nApplying the approximation of pairwise additive CCFs we calculate the radial\ndistribution function of the colloids, which is experimentally accessible. We\nanalyze colloidal aggregation due to CCFs and thus allude to previous\nexperimental studies which are still under debate",
        "positive": "Particle shapes leading to Newtonian dilute suspensions: It is well known that suspensions of particles in a viscous fluid can affect\nthe rheology significantly, producing a pronounced non-Newtonian response even\nin dilute suspension. However, it is unclear a priori which particle shapes\nlead to this behaviour. We present two simple symmetry conditions on the shape\nwhich are sufficient for a dilute suspension to be Newtonian for all strain\nsizes and one sufficient for Newtonian behavior for small strains. We also\nconstruct a class of shapes out of thin, rigid rods not found by the symmetry\nargument which share this property for small strains."
    },
    {
        "anchor": "Introduction to topological defects: from liquid crystals to particle\n  physics: Liquid crystals are assemblies of rod-like molecules which self-organize to\nform mesophases, in-between ordinary liquids and anisotropic crystals. At each\npoint, the molecules collectively orient themselves along a privileged\ndirection, which locally defines an orientational order. Sometimes, this order\nis broken and singularities appear in the form of topological defects. This\ntutorial article is dedicated to the geometry, topology and physics of these\ndefects. We introduce the main models used to describe the nematic phase and\ndiscuss the isotropic-nematic phase transition. Then, we present the different\nfamilies of defects in nematics and examine some of their physical outcomes.\nFinally, we show that topological defects are universal patterns of nature,\nappearing not only in soft matter, but also in biology, cosmology, geology and\neven particle physics.",
        "positive": "Evolution of the social network of scientific collaborations: The co-authorship network of scientists represents a prototype of complex\nevolving networks.\n  By mapping the electronic database containing all relevant journals in\nmathematics and neuro-science for an eight-year period (1991-98), we infer the\ndynamic and the structural mechanisms that govern the evolution and topology of\nthis complex system.\n  First, empirical measurements allow us to uncover the topological measures\nthat characterize the network at a given moment, as well as the time evolution\nof these quantities.\n  The results indicate that the network is scale-free, and that the network\nevolution is governed by preferential attachment, affecting both internal and\nexternal links.\n  However, in contrast with most model predictions the average degree increases\nin time, and the node separation decreases.\n  Second, we propose a simple model that captures the network's time evolution.\n  Third, numerical simulations are used to uncover the behavior of quantities\nthat could not be predicted analytically."
    },
    {
        "anchor": "Weakly polydisperse systems: Perturbative phase diagrams that include\n  the critical region: The phase behaviour of a weakly polydisperse system, such as a colloid with a\nsmall spread of particle sizes, can be related perturbatively to that of its\nmonodisperse counterpart. I show how this approach can be generalized to remain\nwell-behaved near critical points, avoiding the divergences of existing methods\nand giving access to some of the key qualitative features of polydisperse phase\nequilibria. The analysis explains also why in purely size polydisperse systems\nthe critical point is, unusually, located very near the maximum of the cloud\nand shadow curves.",
        "positive": "A Thermodynamic Model of Electric-Field-Induced Pattern Formation in\n  Binary Dielectric Fluids: An electric-field-induced phase transition and pattern formation in a binary\ndielectric fluid layer are studied using a coarse-grained free energy\nfunctional. The electrostatic part of the free energy is a nonlinear functional\nof the dielectric function, which depends in turn on the local colloidal\nconcentration. We determine the phase co-existence curve and find that beyond a\ncritical electric field the system phase separates. Accompanying the phase\nseparation are patterns similar to those observed in a spinodal decomposition\nof an ordinary binary fluid. The temporal evolution of the phase separating\npatterns are discussed both analytically and numerically by integrating a\nCahn-Hilliard type of equation."
    },
    {
        "anchor": "Simulation aspects of patterning polymer films via evaporative\n  lithography and composite substrates: The continuing development of evaporative lithography is important for many\nareas such as the creation of photonic crystals for optronics and\nmicroelectronics, the development of biosensors for medical applications and\nbiotechnology, and for the formation of functional coatings for nanotechnology,\nincluding the application of thin, protective polymer coatings. The article\nproposes a mathematical model that allows us to explain the basic mechanisms of\nthe formation of thin polymer films (less than 50 $\\mu$m thick) during their\ndeposition onto a composite substrate by methanol evaporation from a solution.\nIf the thermal conductivity of the substrate is spatially non-uniform, this\nresults in inhomogeneous evaporation along the free film surface. Therefore, as\nthe film dries, a patterned polymer coating is left behind on the substrate.\nThe mathematical model described here is based on the lubrication approximation\nand takes into account the dependence of the solution density on the\nconcentration. The numerical computation results are in qualitative agreement\nwith the experimental data of other authors. The article shows that solutal\nMarangoni flow plays a primary role in the process under consideration. This\nstudy allows us to better understand the mechanisms that can be used in\nevaporative lithography.",
        "positive": "Nanoscale Observation of Alkane Delayering: Noncontact Atomic Force Microscopy and synchrotron x-ray scattering\nmeasurements on dotriacontane (n-C32H66 or C32) films adsorbed on SiO2-coated\nSi(100) wafers reveal a narrow temperature range near the bulk C32 melting\npoint Tb in which a monolayer phase of C32 molecules oriented perpendicular to\nsurface is stable. This monolayer phase undergoes a delayering transition to a\nthree-dimensional (3D) fluid phase on heating to just above Tb and to a solid\n3D phase on cooling below Tb. An equilibrium phase diagram provides a useful\nframework for interpreting the unusual spreading and receding of the monolayer\nobserved in transitions to and from the respective 3D phases."
    },
    {
        "anchor": "Fluctuating Interfaces in Liquid Crystals: We review and compare recent work on the properties of fluctuating interfaces\nbetween nematic and isotropic liquid-crystalline phases. Molecular dynamics and\nMonte Carlo simulations have been carried out for systems of ellipsoids and\nhard rods with aspect ratio 15:1, and the fluctuation spectrum of interface\npositions (the capillary wave spectrum) has been analyzed. In addition, the\ncapillary wave spectrum has been calculated analytically within the Landau-de\nGennes theory. The theory predicts that the interfacial fluctuations can be\ndescribed in terms of a wave vector dependent interfacial tension, which is\nanisotropic at small wavelengths (stiff director regime) and becomes isotropic\nat large wavelengths (flexible director regime). After determining the elastic\nconstants in the nematic phase, theory and simulation can be compared\nquantitatively. We obtain good agreement for the stiff director regime. The\ncrossover to the flexible director regime is expected at wavelengths of the\norder of several thousand particle diameters, which was not accessible to our\nsimulations.",
        "positive": "Alignment interaction and band formation in assemblies of\n  auto-chemorepulsive walkers: Chemotaxis, i.e. motion generated by chemical gradients, is a motility mode\nshared by many living species that has been developed by evolution to optimize\ncertain biological processes such as foraging or immune response. In\nparticular, auto-chemotaxis refers to chemotaxis mediated by a cue produced by\nthe chemotactic particle itself. Here, we investigate the collective behavior\nof auto-chemotactic particles that are repelled by the cue and therefore\nmigrate preferentially towards low-concentration regions. To this end, we\nintroduce a lattice model inspired by the true self-avoiding walk which reduces\nto the Keller-Segels model in the continuous limit, for which we describe the\nrich phase behavior. We first rationalize a the chemically-mediated alignment\ninteraction between walkers in the limit of stationary concentration fields,\nand then describe the various large-scale structures that can spontaneously\nform and the conditions for them to emerge, among which we find stable bands\ntraveling at constant speed in the direction transverse to the band."
    },
    {
        "anchor": "Lane formation dynamics of oppositely self-driven binary particles:\n  Effects of density and finite system size: We examined the lane formation dynamics of oppositely self-driven binary\nparticles by molecular dynamics simulations of a two-dimensional system. Our\nstudy comprehensively revealed the effects of the density and system size on\nthe lane formation. The phase diagram distinguishing the no-lane and lane\nstates was systematically determined for various combinations of the\nanisotropic friction coefficient and the desired velocity. A peculiar clustered\nstructure was observed when the lane was destroyed by greatly increasing the\ndesired velocity. A strong system size effect was demonstrated by the\nrelationship between the temporal and spatial scales of the lane structure.\nThis system size effect can be attributed to an analogy with the driven lattice\ngas. The transport efficiency was characterized from the scaling relation in\nterms of the degree of lane formation and the interface thickness between\ndifferent lanes.",
        "positive": "Discrete breathers in Fermi-Pasta-Ulam lattices: The Fermi-Pasta-Ulam (FPU) paradox was observed fifty years ago. The\nsurprising finding was a localization of energy in the reciprocal q-space of a\nmodel with discrete translational invariance, despite the presence of\ninteraction between extended normal modes. Thirty three years later Takeno,\nKisoda and Sievers reported on the observation of energy localization in real\nspace for the same class of FPU models, which is as surprising since these\nexcitations, called discrete breathers or intrinsic localized modes, violate\nthe underlying discrete translational symmetry of the model. The past decade\nhas whitnessed a tremendous progress in the theory and applications of discrete\nbreathers, which goes much beyond the scope of the original FPU frame. We use\nthe modern theory of discrete breathers to investigate the properties of these\nsolutions in FPU models, paying special attention to the issues of stability,\nresonances, wave scattering and energy thresholds."
    },
    {
        "anchor": "Capillary imbibition of monodisperse emulsions in confined microfluidic\n  channels: We investigate imbibition of a monodisperse emulsion into a low-aspect ratio\nmicrofluidic channel with the height h comparable to the droplet diameter d.\nFor confinement ratio d/h = 1.2, the tightly confined disk-like droplets in the\nchannel move more slowly compared to the average suspension velocity. Behind\nthe meniscus that drives the imbibition, there is a droplet-free region,\nseparated from the suspension region by a sharp concentration front. The\nsuspension exhibits strong droplet density and velocity fluctuations, but on\naverage, the suspension domain remains uniform. For weaker confinement, d/h =\n0.65, the spherical droplets move faster than the average suspension flow,\nresulting in the formation of a dynamically unstable high-concentration region\nnear the meniscus. We describe the macroscopic suspension dynamics using linear\ntransport equations for the particle-phase flux and suspension flux that are\ndriven by the local pressure gradient. A dipolar particle interaction model\nexplains the observed large density and velocity fluctuations in terms of the\ndynamics of elongated particle clusters with different orientations.",
        "positive": "Elasticity of Twist-Bend Nematic Phases: The ground state of twist-bend nematic liquid crystals is a heliconical\nmolecular arrangement in which the nematic director precesses uniformly about\nan axis, making a fixed angle with it. Both precession senses are allowed in\nthe ground state of these phases. When one of the two \\emph{helicities} is\nprescribed, a single helical nematic phase emerges. A quadratic elastic theory\nis proposed here for each of these phases which features the same elastic\nconstants as the classical theory of the nematic phase, requiring all of them\nto be positive. To describe the helix axis, it introduces an extra director\nfield which becomes redundant for ordinary nematics. Putting together helical\nnematics with opposite helicities, we reconstruct a twist-bend nematic, for\nwhich the quadratic elastic energies of the two helical variants are combined\nin a non-convex energy."
    },
    {
        "anchor": "Time-Dependent Flow in Arrested States -- Transient Behaviour: The transient behaviour of highly concentrated colloidal liquids and\ndynamically arrested states (glasses) under time-dependent shear is reviewed.\nThis includes both theoretical and experimental studies and comprises the\nmacroscopic rheological behaviour as well as changes in the structure and\ndynamics on a microscopic individual-particle level. The microscopic and\nmacroscopic levels of the systems are linked by a comprehensive theoretical\nframework which is exploited to quantitatively describe these systems while\nthey are subjected to an arbitrary flow history. Within this framework,\ntheoretical predictions are compared to experimental data, which were gathered\nby rheology and confocal microscopy experiments, and display consistent\nresults. Particular emphasis is given to (i) switch-on of shear flow during\nwhich the system can liquify, (ii) switch-off of shear flow which might still\nleave residual stresses in the system, and (iii) large amplitude oscillatory\nshearing. The competition between timescales and the dependence on flow history\nleads to novel features in both the rheological response and the microscopic\nstructure and dynamics.",
        "positive": "Interplay between the mechanics of bacteriophage fibers and the strength\n  of virus-host links: Viral fibers play a central role in many virus infection mechanisms since\nthey recognize the corresponding host and establish a mechanical link to its\nsurface. Specifically, bacteriophages have to anchor to bacteria through the\nfibers surrounding the tail before starting the viral DNA translocation into\nthe host. The protein gene product (gp) 37 from bacteriophage T4 long tail\nfibers forms a fibrous parallel homotrimer located at the distal end of the\nlong tail fibers. Biochemical data indicate that, at least three of these\nfibers are required for initial host cell interaction, but do not reveal why\nthree and no other number. By using Atomic Force Microscopy we obtained\nhigh-resolution images of gp37 fibers adsorbed on mica substrate in buffer\nconditions and probed their local mechanical properties. Our experiments of\nradial indentation at the nanometer scale provided a radial stiffness of ~0.08\nN/m and a breaking force of ~120 pN. In addition, we performed Finite Element\nAnalysis and determined a Young's modulus of ~20 MPa. From these mechanical\nparameters, we hypothesize that three viral fibers provide enough mechanical\nstrength to prevent a T4 virus from being detached from the bacteria by the\nviral particle Brownian motion, delivering a biophysical justification of the\nprevious biochemical data."
    },
    {
        "anchor": "Fluid transport by active elastic membranes: A flexible membrane deforming its shape in time can self-propel in a viscous\nfluid. Alternatively, if the membrane is anchored, its deformation will lead to\nfluid transport. Past work in this area focused on situations where the\ndeformation kinematics of the membrane were prescribed. Here we consider models\nwhere the deformation of the membrane is not prescribed, but instead the\nmembrane is internally forced. Both the time-varying membrane shape, and the\nresulting fluid motion, result then from a balance between prescribed internal\nactive stresses, internal passive resistance, and external viscous stresses. We\nintroduce two specific models for such active internal forcing: one where a\ndistribution of active bending moments is prescribed, and one where active\ninclusions exert normal stresses on the membrane by pumping fluid through it.\nIn each case, we asymptotically calculate the membrane shape and the fluid\ntransport velocities for small forcing amplitudes, and recover our results\nusing scaling analysis.",
        "positive": "The impact range for smooth wall-liquid interactions in nanoconfined\n  liquids: Bulk and nanoconfined liquids have initially very different physics; for\ninstance, nanoconfined liquids show stratification and position-dependent\nrelaxation processes. A number of similarities between bulk and nanoconfined\nliquids have nevertheless been reported in computer simulations during the last\ndecade. Inspired by these observations, we present results from molecular\ndynamics computer simulations of three nanoconfined liquids (i.e.,\nsingle-component Lennard-Jones (LJ) liquid, Kob-Andersen binary LJ mixture, and\nan asymmetric dumbbell model) demonstrating also a microscopic similarity\nbetween bulk and nanoconfined liquids. The results show that the interaction\nrange for the wall-liquid and liquid-liquid interactions of the nanoconfined\nliquid are identical to the bulk liquid as long as the liquid remains \"Roskilde\nsimple\" in nanoconfinement, i.e., the liquid has strong correlations between\nvirial and potential energy equilibrium fluctuations in the NVT ensemble."
    },
    {
        "anchor": "Reaction rate of a composite core-shell nanoreactor with multiple,\n  spatially distributed embedded nano-catalysts: We present a detailed theory for the total reaction rate constant of a\ncomposite core-shell nanoreactor, consisting of a central solid core surrounded\nby a hydrogel layer of variable thickness, where a given number of small\ncatalytic nanoparticles are embedded at prescribed positions and are endowed\nwith a prescribed surface reaction rate constant. Besides the precise geometry\nof the assembly, our theory accounts explicitly for the diffusion coefficients\nof the reactants in the hydrogel and in the bulk as well as for their transfer\nfree energy jump upon entering the hydrogel shell. Moreover, we work out an\napproximate analytical formula for the overall rate constant, which is valid in\nthe physically relevant range of geometrical and chemical parameters. We\ndiscuss in depth how the diffusion-controlled part of the rate depends on the\nessential variables, including the size of the central core. In particular, we\nderive some simple rules for estimating the number of nanocatalysts per\nnanoreactor for an efficient catalytic performance in the case of small to\nintermediate core sizes. Our theoretical treatment promises to provide a very\nuseful and flexible tool for the design of superior performing nanoreactor\ngeometries and with optimized nanoparticle load.",
        "positive": "Explosive, oscillatory, and Leidenfrost boiling at the nanoscale: We investigate the different boiling r\\'egimes around a single continuously\nlaser-heated 80 nm gold nanoparticle and draw parallels to the classical\npicture of boiling. Initially, nanoscale boiling takes the form of transient,\ninertia-driven, unsustainable boiling events characteristic of a nanoscale\nboiling crisis. At higher heating power, nanoscale boiling is continuous, with\na vapor film being sustained during heating for at least up to 20 $\\mu$s. Only\nat high heating powers does a substantial stable vapour nanobubble form. At\nintermediate heating powers, unstable boiling sometimes takes the form of\nremarkably stable nanobubble oscillations with frequencies between 40 MHz and\n60 MHz; frequencies that are consistent with the relevant size scales according\nto the Rayleigh-Plesset model of bubble oscillation, though how applicable that\nmodel is to plasmonic vapor nanobubbles is not clear."
    },
    {
        "anchor": "Theoretical correction methods for optical tweezers: Acquisition of\n  potentials of mean forces between colloidal particles in a bulk and on a\n  surface: It is known that line optical tweezers (LOT) can measure potential of mean\nforce (PMF) between colloidal particles in the bulk. However, PMF obtained with\nLOT is empirically modified before showing the result of the final form in\norder to correct the potential rise at long distances. In the present letter,\nwe derive theoretical correction methods for acquisition of PMF by using\nstatistical mechanics. Using the new methods, PMF can be obtained without the\nempirical fitting equation. Through the new methods, external potential acting\non the trapped two colloidal particles induced by LOT can also be obtained. As\nan additional study, we explain two methods for obtaining PMF between colloidal\nparticles on a substrate surface, in which a normal single optical tweezers\nwith a fixed focal point is used, and for obtaining PMF between colloidal\nparticles trapped by dual-beam optical tweezers in the bulk. These methods can\nalso obtain the external potential acting on the trapped two colloidal\nparticles.",
        "positive": "Finite-size effects in the nonphononic density of states in computer\n  glasses: The universal form of the density of nonphononic, quasilocalized vibrational\nmodes of frequency $\\omega$ in structural glasses, ${\\cal D}(\\omega)$, was\npredicted theoretically decades ago, but only recently revealed in numerical\nsimulations. In particular, it has been recently established that, in generic\ncomputer glasses, ${\\cal D}(\\omega)$ increases from zero frequency as\n$\\omega^4$, independent of spatial dimension and of microscopic details.\nHowever, in [E. Lerner, and E. Bouchbinder, Phys. Rev. E 96, 020104(R) (2017)]\nit was shown that the preparation protocol employed to create glassy samples\nmay affect the form of their resulting ${\\cal D}(\\omega)$: glassy samples\nrapidly quenched from high temperature liquid states were shown to feature\n${\\cal D}(\\omega)\\!\\sim\\!\\omega^\\beta$ with $\\beta\\!<\\!4$, presumably limiting\nthe degree of universality of the $\\omega^4$ law. Here we show that exponents\n$\\beta\\!<\\!4$ are only seen in small glassy samples quenched from\nhigh-temperatue liquid states --- whose sizes are comparable to or smaller than\nthe size of the disordered core of soft quasilocalized vibrations --- while\nlarger glassy samples made with the same protocol feature the universal\n$\\omega^4$ law. Our results demonstrate that observations of $\\beta\\!<\\!4$ in\nthe nonphononic density of states stem from finite-size effects, and we thus\nconclude that the $\\omega^4$ law should be featured by any sufficiently large\nglass quenched from a melt."
    },
    {
        "anchor": "Controlling Organization and Forces in Active Matter Through\n  Optically-Defined Boundaries: Living systems are capable of locomotion, reconfiguration, and replication.\nTo perform these tasks, cells spatiotemporally coordinate the interactions of\nforce-generating, \"active\" molecules that create and manipulate non-equilibrium\nstructures and force fields that span up to millimeter length scales [1-3].\nExperimental active matter systems of biological or synthetic molecules are\ncapable of spontaneously organizing into structures [4,5] and generating global\nflows [6-9]. However, these experimental systems lack the spatiotemporal\ncontrol found in cells, limiting their utility for studying non-equilibrium\nphenomena and bioinspired engineering. Here, we uncover non-equilibrium\nphenomena and principles by optically controlling structures and fluid flow in\nan engineered system of active biomolecules. Our engineered system consists of\npurified microtubules and light-activatable motor proteins that crosslink and\norganize microtubules into distinct structures upon illumination. We develop\nbasic operations, defined as sets of light patterns, to create, move, and merge\nmicrotubule structures. By composing these basic operations, we are able to\ncreate microtubule networks that span several hundred microns in length and\ncontract at speeds up to an order of magnitude faster than the speed of an\nindividual motor. We manipulate these contractile networks to generate and\nsculpt persistent fluid flows. The principles of boundary-mediated control we\nuncover may be used to study emergent cellular structures and forces and to\ndevelop programmable active matter devices.",
        "positive": "Accessing a broader range of energy states in metallic glasses by\n  variable-amplitude oscillatory shear: The influence of variable-amplitude loading on the potential energy and\nmechanical properties of amorphous materials is investigated using molecular\ndynamics simulations. We study a binary mixture that is either rapidly or\nslowly cooled across the glass transition temperature and then subjected to a\nsequence of shear cycles with strain amplitudes above and below the yielding\nstrain. It was found that well annealed glasses can be rejuvenated by\nsmall-amplitude loading if the strain amplitude is occasionally increased above\nthe critical value. By contrast, poorly annealed glasses are relocated to\nprogressively lower energy states when subyield cycles are alternated with\nlarge-amplitude cycles that facilitate exploration of the potential energy\nlandscape. The analysis of nonaffine displacements revealed that in both cases,\nthe typical size of plastic rearrangements varies depending on the strain\namplitude and number of cycles, but remains smaller than the system size, thus\npreserving structural integrity of amorphous samples."
    },
    {
        "anchor": "Buckling of paramagnetic chains in soft gels: We study the magneto-elastic coupling behavior of paramagnetic chains in soft\npolymer gels exposed to external magnetic fields. To this end, a laser scanning\nconfocal microscope is used to observe the morphology of the paramagnetic\nchains together with the deformation field of the surrounding gel network. The\nparamagnetic chains in soft polymer gels show rich morphological shape changes\nunder oblique magnetic fields, in particular a pronounced buckling deformation.\nThe details of the resulting morphological shapes depend on the length of the\nchain, the strength of the external magnetic field, and the modulus of the gel.\nBased on the observation that the magnetic chains are strongly coupled to the\nsurrounding polymer network, a simplified model is developed to describe their\nbuckling behavior. A coarse-grained molecular dynamics simulation model\nfeaturing an increased matrix stiffness on the surfaces of the particles leads\nto morphologies in agreement with the experimentally observed buckling effects.",
        "positive": "Anomalous phase behavior of a soft-repulsive potential with a strictly\n  monotonic force: We study the phase behavior of a classical system of particles interacting\nthrough a strictly convex soft-repulsive potential which, at variance with the\npairwise softened repulsions considered so far in the literature, lacks a\nregion of downward or zero curvature. Nonetheless, such interaction is\ncharacterized by two length scales, owing to the presence of a range of\ninterparticle distances where the repulsive force increases, for decreasing\ndistance, much more slowly than in the adjacent regions. We investigate, using\nextensive Monte Carlo simulations combined with accurate free-energy\ncalculations, the phase diagram of the system under consideration. We find that\nthe model exhibits a fluid-solid coexistence line with multiple re-entrant\nregions, an extremely rich solid polymorphism with solid-solid transitions, and\nwater-like anomalies. In spite of the isotropic nature of the interparticle\npotential, we find that, among the crystal structures in which the system can\nexist, there are also a number of non-Bravais lattices, such as cI16 and\ndiamond."
    },
    {
        "anchor": "Finite-Size-Scaling at the Jamming Transition: Corrections to Scaling\n  and the Correlation Length Critical Exponent: We carry out a finite size scaling analysis of the jamming transition in\nfrictionless bi-disperse soft core disks in two dimensions. We consider two\ndifferent jamming protocols: (i) quench from random initial positions, and (ii)\nquasistatic shearing. By considering the fraction of jammed states as a\nfunction of packing fraction for systems with different numbers of particles,\nwe determine the spatial correlation length critical exponent $\\nu\\approx 1$,\nand show that corrections to scaling are crucial for analyzing the data. We\nshow that earlier numerical results yielding $\\nu<1$ are due to the improper\nneglect of these corrections.",
        "positive": "An Underlying Asymmetry within Particle-size Segregation: We experimentally study particle scale dynamics during segregation of a\nbidisperse mixture under oscillatory shear. Large and small particles show an\nunderlying asymmetry that is dependent on the local particle concentration,\nwith small particles segregating faster in regions of many large particles and\nlarge particles segregating slower in regions of many small particles. We\nquantify the asymmetry on bulk and particle scales, and capture it\ntheoretically. This gives new physical insight into segregation and reveals a\nsimilarity with sedimentation, traffic flow and particle diffusion."
    },
    {
        "anchor": "Desalination Performance of Nano porous Mos$_2$ Membrane on Different\n  Salts of Saline Water: A Molecular Dynamics Study: The freshwater crisis is a growing concern and a pressing problem for the\nworld because of the increasing population, civilization, and rapid industrial\ngrowth. The water treatment facilities are able to supply less than 1% of the\ntotal water demand. Water desalination can be a potential solution to deal with\nthis alarming issue. Researchers have been exploring for quite some time to\nfind novel nano-enhanced membranes and manufacturing techniques to increase the\nefficiency of the desalination process. Graphene and graphene modified\nmembranes showed huge potential as desalination membranes for comparatively\neasier synthesis process and higher ion rejection rate than conventional filter\nmaterials. Currently, single-layer Mos$_2$ has been discovered to have the same\npotential of water permeability and ion rejection rate as graphene membrane in\na more energy-efficient way. For almost analogous nano porous structure of the\ngraphene membrane, almost 70% of the higher water flux is obtained from the\nMos$_2$ membrane. In this work, it has been shown that nano porous Mos$_2$\nmembranes provide a promising result for desalinating other salts of seawater\nalongside NaCl. We have also observed the effect of variations in ions, pore\nsize, and pressure on water permeation and ion rejection rates in the water\ndesalination process. In this study, water permeation increased significantly\nby increasing the pore area from 20{\\AA} to 80{\\AA}. The rate of water\nfiltration increases in proportion to both applied pressure and pore size,\nsacrificing the ion rejection rate for the type of ions studied. A combination\nof salt ions in the saline water for desalination has also been studied, where\nthe rejection rates for the different ions are separately represented for\nvarious applied pressures. For seawater, the Mos$_2$ membrane has showed quite\npromising performance in the study of ion variation.",
        "positive": "Tuning contact angles of aqueous droplets on hydrophilic and hydrophobic\n  surfaces by surfactants: Adsorption of small amphiphilic molecules occurs in various biological and\ntechnological processes, sometimes desired, the other times unwanted (e.g.,\ncontamination). Surface-active molecules preferentially bind to interfaces and\naffect their wetting properties. We study the adsorption of short-chained\nalcohols (simple surfactants) to the water-vapor interface and solid surfaces\nof various polarities using molecular dynamics simulations. The analysis\nenables us to establish a theoretical expression for the adsorption\ncoefficient, which exponentially scales with the molecular surface area and the\nsurface wetting coefficient, and which is in good agreement with the simulation\nresults. The competition of the adsorptions to both interfaces of a sessile\ndroplet alters its contact angle in a nontrivial way. The influence of\nsurfactants is strongest on very hydrophilic and very hydrophobic surfaces,\nwhereas droplets on surfaces of moderate hydrophilicity are much less affected."
    },
    {
        "anchor": "Critical wetting in power-law wedge geometries: We investigate critical wetting transitions for fluids adsorbed in wedge-like\ngeometries where the substrate height varies as a power-law, $z(x,y) \\sim |x|\n^\\gamma$, in one direction. As $\\gamma$ is increased from 0 to 1, the substrate\nshape is smoothly changed from a planar-wall to a linear wedge. The continuous\nwetting and filling transitions pertinent to these limiting geometries are\nknown to have distinct phase boundaries and critical singularities. We predict\nthat the intermediate critical wetting behaviour occurring for $0<\\gamma< 1$\nfalls into one of {\\it{three}} possible regimes depending on the values of\n$\\gamma$, p and q. The unbinding behaviour is characterised by a high degree of\nnon-universality, strongly anisotropic correlations and enhanced interfacial\nroughness. The shift in phase boundary and emergence of universal critical\nbehaviour in the linear wedge limit is discussed in detail.",
        "positive": "In-situ measurements of twist and bend elastic constants in oblique\n  helicoidal cholesteric: Unique electro-optical properties of the oblique helicoidal cholesteric\n(ChOH) stem from its heliconical director structure. An applied electric field\npreserves the single harmonic modulation of the director while tuning the ChOH\nperiod and the corresponding Bragg peak wavelength within a broad spectral\nrange. We use the response of ChOH to the electric field to measure the elastic\nconstants of twist K22 and bend K33 directly in the cholesteric phase. The\ntemperature dependencies of K22 and K33 allow us to determine the range of the\nelectric tunability of the ChOH pitch and the heliconical angle. The data are\nimportant for understanding how molecular composition and chirality influence\nmacroscopic elastic properties of the chiral liquid crystals and for the\ndevelopment of ChOH-based optical devices."
    },
    {
        "anchor": "Supervised and Unsupervised Machine Learning of Structural Phases of\n  Polymers Adsorbed to Nanowires: We identify configurational phases and structural transitions in a polymer\nnanotube composite by means of machine learning. We employ various unsupervised\ndimensionality reduction methods, conventional neural networks, as well as the\nconfusion method, an unsupervised neural-network-based approach. We find neural\nnetworks are able to reliably recognize all configurational phases that have\nbeen found previously in experiment and simulation. Furthermore, we locate the\nboundaries between configurational phases in a way that removes human intuition\nor bias. This could be done before only by relying on preconceived, ad-hoc\norder parameters.",
        "positive": "Fluid and solid phases of the Gaussian core model: We study the structural and thermodynamic properties of a model of point\nparticles interacting by means of a Gaussian pair potential first introduced by\nStillinger [Stillinger F H 1976 J. Chem. Phys. 65, 3968]. By employing integral\nequation theories for the fluid state and comparing with Monte Carlo simulation\nresults, we establish the limits of applicability of various common closures\nand examine the dependence of the correlation functions of the liquid on the\ndensity and temperature. We employ a simple, mean-field theory for the high\ndensity domain of the liquid and demonstrate that at infinite density the\nmean-field theory is exact and that the system reduces to an `infinite density\nideal gas', where all correlations vanish and where the hypernetted chain (HNC)\nclosure becomes exact. By employing an Einstein model for the solid phases, we\nsubsequently calculate quantitatively the phase diagram of the model and find\nthat the system possesses two solid phases, face centered cubic and body\ncentered cubic, and also displays reentrant melting into a liquid at high\ndensities. Moreover, the system remains fluid at all densities when the\ntemperature exceeds 1% of the strength of the interactions."
    },
    {
        "anchor": "Defect-Mediated Phase Transitions in Active Soft Matter: How do topological defects affect the degree of order in active matter? To\nanswer this question we investigate an agent-based model of self-propelled\nparticles, which accounts for polar alignment and short-ranged repulsive\ninteractions. For strong alignment forces we find collectively moving\npolycrystalline states with fluctuating networks of grain boundaries. In the\nregime where repulsive forces dominate, the fluctuations generated by the\nactive system give rise to quasi-long-range transitional order, but---unlike\nthermal system---without creating topological defects.",
        "positive": "Generalized van der Waals theory for the twist elastic modulus and\n  helical pitch of cholesterics: We present a generalized van der Waals theory for a lyotropic cholesteric\nsystem of chiral spherocylinders based on the classical Onsager theory for hard\nanisometric bodies. The rods consist of a hard spherocylindrical backbone\nsurrounded with a square-well potential to account for attractive (or soft\nrepulsive) interactions. Long-ranged chiral interactions are described by means\nof a simple pseudo-scalar potential which is appropriate for weak chiral forces\nof a predominant electrostatic origin. Based on the formalism proposed by\nStraley [Phys. Rev. A {\\bf 14}, 1835 (1976)] we derive explicit algebraic\nexpressions for the twist elastic modulus and the cholesteric pitch for rods as\na function of density and temperature. The pitch varies non-monotonically with\ndensity, with a sharp decrease at low packing fractions and a marked increase\nat higher packing fractions. A similar trend is found for the temperature\ndependence. The unwinding of the helical pitch at high densities (or low\ntemperatures) originates from a marked increase in the local nematic order and\na steep increase of the twist elastic resistance associated with near-parallel\nlocal rod configurations. This contrasts with the commonly held view that the\nincrease in pitch with decreasing temperature as often observed in cholesterics\nis due to layer formation resulting from pre-smectic fluctuations. The increase\nin pitch with increasing temperature is consistent with an entropic unwinding\nas the chiral interaction becomes less and less significant than the thermal\nenergy. The variation of the pitch with density, temperature and contour length\nis in qualitative agreement with recent experimental results on colloidal {\\em\nfd} rods."
    },
    {
        "anchor": "Sample-to-sample fluctuations of electrostatic forces generated by\n  quenched charge disorder: It has been recently shown that randomly charged surfaces can exhibit long\nrange electrostatic interactions even when they are net neutral. These forces\ndepend on the specific realization of charge disorder and thus exhibit sample\nto sample fluctuations about their mean value. We analyze the fluctuations of\nthese forces in the parallel slab configuration and also in the sphere-plane\ngeometry via the proximity force approximation. The fluctuations of the normal\nforces, that have a finite mean value, are computed exactly. Surprisingly, we\nalso show that lateral forces are present, despite the fact that they have a\nzero mean, and that their fluctuations have the same scaling behavior as the\nnormal force fluctuations. The measurement of these lateral force fluctuations\ncould help to characterize the effects of charge disorder in experimental\nsystems, leading to estimates of their magnitudes that are complementary to\nthose given by normal force measurements.",
        "positive": "Non-Equilibrium Markov State Modeling of the Globule-Stretch Transition: We describe a systematic approach to construct coarse-grained Markov state\nmodels from molecular dynamics data of systems driven into a non-equilibrium\nsteady state. We apply this method to study the globule-stretch transition of a\nsingle tethered model polymer in shear flow. The folding/unfolding rates of the\ncoarse-grained model agree with the original detailed model. We demonstrate\nthat the folding/unfolding proceeds through the same narrow region of\nconfiguration space but along different cycles."
    },
    {
        "anchor": "Thermal conductivity of bottle-brush polymers: Using molecular dynamics (MD) simulations of a generic model, we investigate\nheat propagation in bottle--brush polymers (BBP). An architecture is referred\nto as a BBP when a linear (backbone) polymer is grafted with the side chains of\ndifferent length $N_{\\rm s}$ and grafting density $\\rho_{\\rm g}$, which control\nthe bending stiffness of a backbone. A BBP is of particular interest due to two\ncompeting mechanics: increased backbone stiffness, via $N_{\\rm s}$ and\n$\\rho_{\\rm g}$, increases the thermal transport coefficient $\\kappa$, while the\npresence of side chains provides additional pathways for heat leakage. We show\nhow a delicate competition between these two effects controls $\\kappa$. These\nresults reveal that going from a weakly grafting ($\\rho_{\\rm g} < 1$) to a\nhighly grafting ($\\rho_{\\rm g} \\ge 1$) regime, $\\kappa$ changes\nnon--monotonically that is independent of $N_{\\rm s}$. The effect of side chain\nmass on $\\kappa$ and heat flow in the BBP melts are also discussed.",
        "positive": "In-situ synchrotron microtomography reveals multiple reaction pathways\n  during soda-lime glass synthesis: Ultrafast synchrotron microtomography has been used to study in-situ and in\nreal time the initial stages of silicate glass melt formation from crystalline\ngranular raw materials. Significant and unexpected rearrangements of grains\noccur below the nominal eutectic temperature, and several drastically different\nsolid-state reactions are observed to take place at different types of\nintergranular contacts. These reactions have a profound influence on the\nformation and the composition of the liquids produced, and control the\nformation of defects."
    },
    {
        "anchor": "Microparticles self-assembly induced by travelling surface acoustic\n  waves: We present an acoustofluidic method based on travelling surface acoustic\nwaves (TSAWs) for the induction of the self-assembly of microparticles inside a\nmicrofluidic channel. The particles are trapped above an interdigitated\ntransducer, placed directly beneath the microchannel, by the TSAW-based direct\nacoustic radiation force (ARF). This approach was applied to 10 {\\mu}m\npolystyrene particles, which were pushed towards the ceiling of the\nmicrochannel by 72 MHz TSAWs to form single- and multiple-layer colloidal\nstructures. The repair of cracks and defects within the crystal lattice occurs\nas part of the self-assembly process. The sample flow through the first inlet\ncan be switched with a buffer flow through a second inlet to control the number\nof particles in the crystalline structure. The constant flow-induced Stokes\ndrag force on the parti-cles is balanced by the opposing TSAW-based ARF. This\nforce balance is essential for the acoustics-based self-assembly of\nmicroparticles inside the microchannel. Moreover, we studied the effects of\nvarying the input voltage and fluid flow rate on the position and shape of the\ncolloidal structure. The active self-assembly of microparticles into crystals\nwith multiple layers can be used in the bottom-up fabrication of colloidal\nstructures with dimensions greater than 500 {\\mu}m x 500 {\\mu}m, which is\nexpected to have important applications in various fields.",
        "positive": "Occurrence of gradual resonance in a finite-length granular chain driven\n  by harmonic vibration: This study presents numerical simulations of the resonance of a finite-length\ngranular chain of dissipative grains driven by a harmonically vibrated tube.\nMultiple gradual resonant modes, namely, non-resonance mode, partial-resonance\nmode, and complete-resonance mode, are identified. With a fixed vibration\nfrequency, increased vibration acceleration leads to a one-by-one increase in\nthe number of grains participating in resonance, which is equal to the number\nof grain-wall collisions in a vibration period. Compared with the\ncharacteristic time of the grain-grain and the grain-wall collisions, the time\nof free flight plays a dominant role in grain motion. This condition results in\nthe occurrence of large opening gaps between the grains and independent\ngrain-grain and gain-wall collisions. A general master equation that describes\nthe dependence of the system energy on the length of the granular chain and the\nnumber of grain-wall collisions is established, and it is in good agreement\nwith the simulation results. We observe a gradual step-jump increase in system\nenergy when the vibration acceleration is continuously increased, which is\ndedicated to an individual energy injection. Moreover, two typical phase\ndiagrams are discussed in the spaces of $\\phi-\\it{\\Gamma}$ and $N-\\it\\Gamma$."
    },
    {
        "anchor": "Dissipative magneto-optic solitons: Magneto-optic behaviour is a specific, non-reciprocal example of gyrotropic\nbehaviour. When coupled to photo-induced Faraday rotation it is possible to\ndiscriminate this effect from the background of other nonlinear effects\nNon-reciprocal behaviour is characteristic of artificial gyrotropy and can be\nused in optical isolators and a range of coherence and quantum problems. This\nis all in sharp contrast to natural gyrotropy, like optical activity. it is\nalso important to go beyond third-order, Kerr, optical nonlinearity and move\ntowards a saturable model of terms in the polarisation. In this spirit, this\nchapter seeks to determinate the influence of a magneto-optic presence upon an\noptically nonlinear material that is modelled by a cubic-quintic form of\npolarisation. In addition, the coefficients of the envelope equation will be\nmade complex, to take into account both linear and nonlinear damping and cubic\ngain processes. The emphasis is upon the simulation outcomes, however, rather\nthe applications.",
        "positive": "Amino acid-driven hydrophobization of alumina and production of particle\n  stabilised foams in a broader pH range: The interaction of amino acids (glycine, L-valine, L-isoleucine and\nL-leucine) with alumina surface was studied to induce partial hydrophobization\nand production of ultrastable particle-stabilised foams. The evaluation of\nthese amino acids was carried out by mechano-quantum simulations followed by\nexperimental tests (foamability, zeta potential, contact angle and foam\nlifetime measurements). The experimental results agreed with the trends pointed\nout by the simulations. The selected amino acids interact with alumina\nparticles in aqueous media and in a broader pH range, leading to\nhydrophobization of surfaces, which was more intense for amino acids with\nhigher molecular mass (isoleucine and leucine). As a consequence, ultrastable\nfoams with a longer lifetime (> 100 hours) were produced and the foam\nmicrostructure was preserved from ageing phenomena. Moreover, the attained\nfoams were stable at different pH, opening up new possibilities to develop\nmacroporous multiphasic ceramics, which can result in novel materials for\nthermal insulation at high temperatures."
    },
    {
        "anchor": "On the Dynamics and Disentanglement in Thin and Two-Dimensional Polymer\n  Films: We present results from molecular dynamics simulations of strictly\ntwo-dimensional (2D) polymer melts and thin polymer films in a slit geometry of\nthickness of the order of the radius of gyration. We find that the dynamics of\nthe 2D melt is qualitatively different from that of the films. The 2D monomer\nmean-square displacement shows a $t^{8/15}$ power law at intermediate times\ninstead of the $t^{1/2}$ law expected from Rouse theory for nonentangled\nchains. In films of finite thickness, chain entanglements may occur. The impact\nof confinement on the entanglement length $N_\\mathrm{e}$ has been analyzed by a\nprimitive path analysis. The analysis reveals that $N_\\mathrm{e}$ increases\nstrongly with decreasing film thickness.",
        "positive": "Attraction and unbinding of like-charged rods: We investigate the effective interaction between two like-charged rods in the\nregime of large electrostatic coupling parameters using both Molecular Dynamics\nsimulation techniques and the recently introduced strong-coupling theory. We\nobtain attraction between the rods for elevated Manning parameters accompanied\nby an equilibrium surface-to-surface separation of the order of the\nGouy-Chapman length. A continuous unbinding between the rods is predicted at a\nthreshold Manning parameter of 2/3."
    },
    {
        "anchor": "Fluid-fluid demixing curves for colloid-polymer mixtures in a random\n  colloidal matrix: We study fluid-fluid phase separation in a colloid-polymer mixture adsorbed\nin a colloidal porous matrix close to the \\theta -point. For this purpose we\nconsider the Asakura-Oosawa model in the presence of a quenched matrix of\ncolloidal hard spheres. We study the dependence of the demixing curve on the\nparameters that characterize the quenched matrix, fixing the polymer-to-colloid\nsize ratio to 0.8. We find that, to a large extent, demixing curves depend only\non a single parameter f, which represents the volume fraction which is\nunavailable to the colloids. We perform Monte Carlo simulations for volume\nfractions f equal to 40% and 70%, finding that the binodal curves in the\npolymer and colloid packing-fraction plane have a small dependence on disorder.\nThe critical point instead changes significantly: for instance, the colloid\npacking fraction at criticality increases with increasing f. Finally, we\nobserve for some values of the parameters capillary condensation of the\ncolloids: a bulk colloid-poor phase is in chemical equilibrium with a\ncolloid-rich phase in the matrix.",
        "positive": "Growth of Smaller Grain Attached on Larger One: Algorithm to Overcome\n  Unphysical Overlap between Grain: As a smaller grain, which is attached on larger one, is growing, it pushes\nalso the larger one and other grains in its surrounding. In a simulation of\nsimilar system, repulsive force such as contact force based on linear\nspring-dashpot model can not accommodate this situation when cell growing rate\nis faster than simulation time step, since it produces sudden large overlap\nbetween grains that makes unphysical result. An algorithm that preserves system\nlinear momentum by introducing additional velocity induced by cell growth is\npresented in this work. It should be performed in an implicit step. The\nalgorithm has successfully eliminated unphysical overlap."
    },
    {
        "anchor": "Delayed elastic contributions to the viscoelastic response of foams: We show that the slow viscoelastic response of a foam is that of a power-law\nfluid with a terminal relaxation. Investigations of the foam mechanics in creep\nand recovery tests reveal that the power-law contribution is fully reversible,\nindicative of a delayed elastic response. We demonstrate how this contribution\nfully accounts for the non-Maxwellian features observed in all tests, probing\nthe linear mechanical response function. The associated power-law spectrum is\nconsistent with soft glassy rheology of systems with mechanical noise\ntemperatures just above the glass transition [Fielding et al., J.Rheol. 44,\n323(2000)] and originates from a combination of superdiffusive bubble dynamics\nand stress diffusion, as recently evidenced in simulations of coarsening foam\n[Hwang et al., Nat.Mater. 15, 1031 (2016)].",
        "positive": "Ferromagnetic and antiferromagnetic order in bacterial vortex lattices: Despite their inherent non-equilibrium nature, living systems can\nself-organize in highly ordered collective states that share striking\nsimilarities with the thermodynamic equilibrium phases of conventional\ncondensed matter and fluid systems. Examples range from the liquid-crystal-like\narrangements of bacterial colonies, microbial suspensions and tissues to the\ncoherent macro-scale dynamics in schools of fish and flocks of birds. Yet, the\ngeneric mathematical principles that govern the emergence of structure in such\nartificial and biological systems are elusive. It is not clear when, or even\nwhether, well-established theoretical concepts describing universal\nthermostatistics of equilibrium systems can capture and classify ordered states\nof living matter. Here, we connect these two previously disparate regimes:\nThrough microfluidic experiments and mathematical modelling, we demonstrate\nthat lattices of hydrodynamically coupled bacterial vortices can spontaneously\norganize into distinct phases of ferro- and antiferromagnetic order. The\npreferred phase can be controlled by tuning the vortex coupling through changes\nof the inter-cavity gap widths. The emergence of opposing order regimes is\ntightly linked to the existence of geometry-induced edge currents, reminiscent\nof those in quantum systems. Our experimental observations can be rationalized\nin terms of a generic lattice field theory, suggesting that bacterial spin\nnetworks belong to the same universality class as a wide range of equilibrium\nsystems."
    },
    {
        "anchor": "Predicting plasticity in disordered solids from structural indicators: Amorphous solids lack long-range order. Therefore identifying structural\ndefects -- akin to dislocations in crystalline solids -- that carry plastic\nflow in these systems remains a daunting challenge. By comparing many different\nstructural indicators in computational models of glasses, under a variety of\nconditions we carefully assess which of these indicators are able to robustly\nidentify the structural defects responsible for plastic flow in amorphous\nsolids. We further demonstrate that the density of defects changes as a\nfunction of material preparation and strain in a manner that is highly\ncorrelated with the macroscopic material response. Our work represents an\nimportant step towards predicting how and when an amorphous solid will fail\nfrom its microscopic structure.",
        "positive": "Activity gradients in two- and three-dimensional active nematics: We numerically investigate how spatial variations of extensile or contractile\nactive stress affect bulk active nematic systems in two and three dimensions.\nIn the absence of defects, activity gradients drive flows which re-orient the\nnematic director field and thus act as an effective anchoring force. At high\nactivity, defects are created and the system transitions into active\nturbulence, a chaotic flow state characterized by strong vorticity. We find\nthat in two-dimensional (2D) systems active torques robustly align $+1/2$\ndefects parallel to activity gradients, with defect heads pointing towards\ncontractile regions. In three-dimensional (3D) active nematics disclination\nlines preferentially lie in the plane perpendicular to activity gradients due\nto active torques acting on line segments. The average orientation of the\ndefect structures in the plane perpendicular to the line tangent depends on the\ndefect type, where wedge-like $+1/2$ defects align parallel to activity\ngradients, while twist defects are aligned anti-parallel. Understanding the\nresponse of active nematic fluids to activity gradients is an important step\ntowards applying physical theories to biology, where spatial variations of\nactive stress impact morphogenetic processes in developing embryos and affect\nflows and deformations in growing cell aggregates, such as tumours."
    },
    {
        "anchor": "How does the presence of stevia glycosides impact surface bubbles\n  stability?: The addition of sweeteners in fizzy beverages not only affects the sugar\ncontent but also the bubbles stability. In this article, we propose a model\nexperiment, in which the lifetime of hundreds of single bubbles is measured, to\nassess the stability of bubbles in solutions containing either sucrose or\nsweeteners. We show that the bubbles are indeed more stable in presence of\nsweeteners, which are surface active molecules and adsorb at the interface.\nAdditionally, we test an antifoam at different concentrations and show that our\nexperiment allows to identify the best concentration to reproduce the stability\nobtained in sucrose when we replace this latter by a sweetener.",
        "positive": "Marangoni stress induced by rotation frustration in a liquid foam: The role of surface tension gradients in the apparent viscosity of liquid\nfoams remains largely unexplained. In this article, we develop a toy-model\nbased on a periodic array of 2D hexagonal bubbles, each bubble being separated\nfrom its neighbors by a liquid film of uniform thickness. The two interfaces of\nthis thin liquid film are allowed to slide relatively to each other, thus\nshearing the liquid phase in between. We solve the dynamics under external\nshear of this minimal system and we show that the continuity of the surface\ntension around the whole bubble is the relevant condition to determine the\nbubble rotation rate and the energy dissipation. This result is expected to be\nrobust in more complex situations and illustrates that thin film dynamics\nshould be solve at the scale of the whole bubble interface when interface\nrheology matters."
    },
    {
        "anchor": "Polymer Segmental Cross-Correlations from Dielectric Relaxation Spectra\n  of Block Copolymers: Dielectric relaxation spectra of block polymers containing sequential type-A\ndipoles are considered. Spectra of a specific set of block copolymers can be\ncombined to isolate the dynamic cross-correlation between the motions of two\ndistinct parts of the same polymer chain. Unlike past treatments of this\nproblem, no model is assumed for the underlying polymer dynamics.",
        "positive": "Dynamics of a suspension of interacting yolk-shell particles: In this work we study the self-diffusion properties of a liquid of hollow\nspherical particles (shells)bearing a smaller solid sphere in their interior\n(yolks). We model this system using purely repulsive hard-body interactions\nbetween all (shell and yolk) particles, but assume the presence of a background\nideal solvent such that all the particles execute free Brownian motion between\ncollisions,characterized by short-time self-diffusion coefficients D0s for the\nshells and D0y for the yolks. Using a softened version of these interparticle\npotentials we perform Brownian dynamics simulations to determine the mean\nsquared displacement and intermediate scattering function of the yolk-shell\ncomplex. These results can be understood in terms of a set of effective\nLangevin equations for the N interacting shell particles, pre-averaged over the\nyolks' degrees of freedom, from which an approximate self-consistent\ndescription of the simulated self-diffusion properties can be derived. Here we\ncompare the theoretical and simulated results between them, and with the\nresults for the same system in the absence of yolks. We find that the yolks,\nwhich have no effect on the shell-shell static structure, influence the dynamic\nproperties in a predictable manner, fully captured by the theory."
    },
    {
        "anchor": "Mixing Grains with Different Elongation in a Rotating Drums: Mixing grains with different properties is a remarkably challenging process,\nrelevant to many industrial applications. Rotating drums have been used\nextensively as model systems to study granular media flow and mixing and\nsegregation. Numerous studies considered the mixing of grains with different\nsizes, but only few studies considered shape and elongation, which have been\nalready identified as important characteristics affecting packing and inducing\nsegregation. In this contribution, the mixing of binary mixtures of grains\nhaving the same volume, but different elongations was studied experimentally.\nThe mixing dynamics of a layered granular medium was characterized in a\nrotating drum, highlighting the impact of the grain shape, of the drum angular\nspeed and of the drum filling ratio. A mixed or segregated state is reached\nvery rapidly, but experiments are continued to verify that the state reached is\na steady state. The experiments demonstrated that below a critical difference\nof elongation, the grains can be mixed effectively. Conversely, when grain\nelongations are very different, a central core is formed, rich in the more\nelongated grains. In this case only limited mixing can be achieved. These\nresults can guide the formulation of mixtures of grains with different\nelongations.",
        "positive": "Predicting permeability via statistical learning on higher-order\n  microstructural information: Quantitative structure-property relationships are crucial for the\nunderstanding and prediction of the physical properties of complex materials.\nFor fluid flow in porous materials, characterizing the geometry of the pore\nmicrostructure facilitates prediction of permeability, a key property that has\nbeen extensively studied in material science, geophysics and chemical\nengineering. In this work, we study the predictability of different structural\ndescriptors via both linear regressions and neural networks. A large data set\nof 30,000 virtual, porous microstructures of different types is created for\nthis end. We compute permeabilities of these structures using the lattice\nBoltzmann method, and characterize the pore space geometry using one-point\ncorrelation functions (porosity, specific surface), two-point surface-surface,\nsurface-void, and void-void correlation functions, as well as the geodesic\ntortuosity as an implicit descriptor. Then, we study the prediction of the\npermeability using different combinations of these descriptors. We obtain\nsignificant improvements of performance when compared to a Kozeny-Carman\nregression with only lowest-order descriptors (porosity and specific surface).\nWe find that combining all three two-point correlation functions and tortuosity\nprovides the best prediction of permeability, with the void-void correlation\nfunction being the most informative individual descriptor. Moreover, the\ncombination of porosity, specific surface, and geodesic tortuosity provides\nvery good predictive performance. This shows that higher-order correlation\nfunctions are extremely useful for forming a general model for predicting\nphysical properties of complex materials. Additionally, our results suggest\nthat neural networks are superior to the more conventional regression methods\nfor establishing quantitative structure-property relationships."
    },
    {
        "anchor": "Electrostatic interaction of particles trapped at fluid interfaces:\n  Effects of geometry and wetting properties: The electrostatic interaction between pairs of spherical or macroscopically\nlong, parallel cylindrical colloids trapped at fluid interfaces is studied\ntheoretically for the case of small inter-particle separations. Starting from\nthe effective interaction between two planar walls and by using the Derjaguin\napproximation, we address the issue of how the electrostatic interaction\nbetween such particles is influenced by their curvatures and by the wetting\ncontact angle at their surfaces. Regarding the influence of curvature, our\nfindings suggest that the discrepancies between linear and nonlinear\nPoisson-Boltzmann theory, which have been noticed before for planar walls, also\noccur for spheres and macroscopically long, parallel cylinders, though their\nmagnitude depends on the wetting contact angle. Concerning the influence of the\nwetting contact angle $\\theta$ simple relations are obtained for equally sized\nparticles which indicate that the inter-particle force varies significantly\nwith $\\theta$ only within an interval around $90^\\circ$. This interval depends\non the Debye length of the fluids and on the size of the particles but not on\ntheir shape. For unequally sized particles, a more complicated relation is\nobtained for the variation of the inter-particle force with the wetting contact\nangle.",
        "positive": "Introducing Protein Folding Using Simple Models: We discuss recent theoretical developments in the study of simple lattice\nmodels of proteins. Such models are designed to understand general features of\nprotein structures and mechanism of folding. Among the topics covered are (i)\nthe use of lattice models to understand the selection of the limited set of\nviable protein folds; (ii) the relationship between structure and sequence\nspaces; (iii) the application of lattice models for studying folding mechanisms\n(topological frustration, kinetic partitioning mechanism). Classification of\nfolding scenarios based on the intrinsic thermodynamic properties of a sequence\n(namely, the collapse and folding transition temperatures) is outlined. A brief\ndiscussion of random heteropolymer model is also presented."
    },
    {
        "anchor": "Phase diagram of the Gaussian-core model: We trace with unprecedented numerical accuracy the phase diagram of the\nGaussian-core model, a classical system of point particles interacting via a\nGaussian-shaped, purely repulsive potential. This model, which provides a\nreliable qualitative description of the thermal behavior of interpenetrable\nglobular polymers, is known to exhibit a polymorphic FCC-BCC transition at low\ndensities and reentrant melting at high densities. Extensive Monte Carlo\nsimulations, carried out in conjunction with accurate calculations of the solid\nfree energies, lead to a thermodynamic scenario that is partially modified with\nrespect to previous knowledge. In particular, we find that: i) the\nfluid-BCC-FCC triple-point temperature is about one third of the maximum\nfreezing temperature; ii) upon isothermal compression, the model exhibits a\nfluid-BCC-FCC-BCC-fluid sequence of phases in a narrow range of temperatures\njust above the triple point. We discuss these results in relation to the\nbehavior of star-polymer solutions and of other softly repulsive systems.",
        "positive": "Wigner crystals for a planar, equimolar binary mixture of classical,\n  charged particles: We have investigated the ground state configurations of an equimolar, binary\nmixture of classical charged particles (with nominal charges $Q_1$ and $Q_2$)\nthat condensate on a neutralizing plane. Using efficient Ewald summation\ntechniques for the calculation of the ground state energies, we have identified\nthe energetically most favourable ordered particle arrangements with the help\nof a highly reliable optimization tool based on ideas of evolutionary\nalgorithms. Over a large range of charge ratios, $q = Q_2 / Q_1$, we identify\nsix non-trivial ground states, some of which show a remarkable and unexpected\nstructural complexity. For $0.59 \\lesssim q < 1$ the system undergoes a phase\nseparation where the two charge species populate in a hexagonal arrangement\nspatially separated areas."
    },
    {
        "anchor": "Coarse-graining strategy for modeling effective, highly diffusive fluids\n  with reduced polydispersity: A dynamical study: We present a coarse-graining strategy for reducing the number of particle\nspecies in mixtures to achieve a simpler system with higher diffusion while\npreserving the total particle number and characteristic dynamic features. As a\nsystem of application, we chose the bidisperse Lennard-Jones-like mixture\ndiscovered by Kob and Andersen [Phys. Rev. Lett. 73, 1376 (1994)] possessing a\nslow dynamics due to the fluid's multi-component character with its apparently\nunconventional choice for the pair potential of the type-A-type-B arrangement.\nWe further established in a so-formed coarse-grained and\ntemperature-independent monodisperse system an equilibrium structure with a\nradial distribution function resembling its mixture counterpart. This\none-component system further possesses similar dynamic features like glass\ntransition temperature and critical exponents while subjected to Newtonian\nmechanics. This strategy may finally lead to the manufacturing of new\nnanoparticle/colloidal fluids by experimentally modeling only the outcoming\neffective pair potential(s) and no other macroscopic quantity.",
        "positive": "Monitoring Three-Dimensional Packings in Microgravity: We present results from experiments with granular packings in three\ndimensions in microgravity as realized on parabolic flights. Two different\ntechniques are employed to monitor the inside of the packings during\ncompaction: (1) X-ray radiography is used to measure in transmission the\nintegrated fluctuations of particle positions. (2) Stress-birefringence in\nthree dimensions is applied to visualize the stresses inside the packing. The\nparticle motions below the transition into an arrested packing are found to\nproduce a well agitated state. At the transition, the particles lose their\nenergy quite rapidly and form a stress network. With both methods, non-arrested\nparticles (rattlers) can be identified. In particular, it is found that\nrattlers inside the arrested packing can be excited to appreciable dynamics by\nthe rest-accelerations (g-jitter) during a parabolic flight without destroying\nthe packings. At low rates of compaction, a regime of slow granular cooling is\nidentified. The slow cooling extends over several seconds, is described well by\na linear law, and terminates in a rapid final collapse of dynamics before\ncomplete arrest of the packing."
    },
    {
        "anchor": "How motility drives the glassy dynamics in confluent epithelial\n  monolayers?: As wounds heal, embryos develop, cancer spreads, or asthma progresses, the\ncellular monolayer undergoes a glass transition from a solid-like jammed to a\nfluid-like flowing state. Two primary characteristics of these systems,\nconfluency, and self-propulsion, make them distinct from particulate systems.\nAre the glassy dynamics in these biological systems and equilibrium particulate\nsystems different? Despite the biological significance of glassiness in these\nsystems, no analytical framework, which is indispensable for deeper insights,\nexists. Here, we extend one of the most popular theories of equilibrium\nglasses, the random first-order transition (RFOT) theory, for confluent systems\nwith self-propulsion. One crucial result of this work is that, unlike in\nparticulate systems, the confluency affects the effective persistence\ntime-scale of the active force, described by its rotational diffusion\n$D_r^{\\text{eff}}$. Unlike in particulate systems, this value differs from the\nbare rotational diffusion of the active propulsion force due to cell shape\ndynamics which acts to rectify the force dynamics: $D_r^{\\text{eff}}$ is equal\nto $D_r$ when $D_r$ is small, and saturates when $D_r$ is large. We present\nsimulation results for the glassy dynamics in active confluent models and find\nthat the results are consistent with existing experimental data, and conform\nremarkably well with our theory. In addition, we show that the theoretical\npredictions agree nicely with and explain previously published simulation\nresults. Our analytical theory provides a foundation for rationalizing and a\nquantitative understanding of various glassy characteristics of these\nbiological systems.",
        "positive": "Force-induced rupture of a DNA duplex: The rupture of double-stranded DNA under stress is a key process in\nbiophysics and nanotechnology. In this article we consider the shear-induced\nrupture of short DNA duplexes, a system that has been given new importance by\nrecently designed force sensors and nanotechnological devices. We argue that\nrupture must be understood as an activated process, where the duplex state is\nmetastable and the strands will separate in a finite time that depends on the\nduplex length and the force applied. Thus, the critical shearing force required\nto rupture a duplex within a given experiment depends strongly on the time\nscale of observation. We use simple models of DNA to demonstrate that this\napproach naturally captures the experimentally observed dependence of the\ncritical force on duplex length for a given observation time. In particular,\nthe critical force is zero for the shortest duplexes, before rising sharply and\nthen plateauing in the long length limit. The prevailing approach, based on\nidentifying when the presence of each additional base pair within the duplex is\nthermodynamically unfavorable rather than allowing for metastability, does not\npredict a time-scale-dependent critical force and does not naturally\nincorporate a critical force of zero for the shortest duplexes. Additionally,\nmotivated by a recently proposed force sensor, we investigate application of\nstress to a duplex in a mixed mode that interpolates between shearing and\nunzipping. As with pure shearing, the critical force depends on the time scale\nof observation; at a fixed time scale and duplex length, the critical force\nexhibits a sigmoidal dependence on the fraction of the duplex that is subject\nto shearing."
    },
    {
        "anchor": "Interactions between Charged Particles with bathing Multivalent\n  Counterions: Experiments {\\it vs} Dressed Ion Theory: We compare the recent experimentally measured forces between charged\ncolloidal particles, as well as their effective surface potentials (surface\ncharge) in the presence of multivalent counterions in a bathing monovalent salt\nsolution, with the predictions of the dressed ion theory of strongly charged\ncolloidal systems. The benchmark for comparison is provided by the DLVO theory\nand the deviations from its predictions at small separations are taken as an\nindication of the additional non-DLVO attractions that can be fitted by an\nadditional phenomenological exponential term. The parameters characterizing\nthis non-DLVO exponential term as well as the dependencies of the effective\npotential on the counterion concentration and valency predicted by the dressed\nion theory are well within the experimental values. This suggests that the\ndeviations from the DLVO theory are probably caused by ion correlations as\nformalized within the dressed ion theory.",
        "positive": "Normal stress differences in dense suspensions: The presence and the microscopic origin of normal stress differences in dense\nsuspensions under simple shear flows are investigated by means of inertialess\nparticle dynamics simulations, taking into account hydrodynamic lubrication and\nfrictional contact forces. The synergic action of hydrodynamic and contact\nforces between the suspended particles is found to be the origin of negative\ncontributions to the first normal stress difference $N_1$, whereas positive\nvalues of $N_1$ observed at higher volume fractions near jamming are due to\neffects that cannot be accounted for in the hard-sphere limit. Furthermore, we\nfound that the stress anisotropy induced by the planarity of the simple shear\nflow vanishes as the volume fraction approaches the jamming point for\nfrictionless particles, while it remains finite for the case of frictional\nparticles."
    },
    {
        "anchor": "Obituary for Stefan U. Egelhaaf: This is a tribute to honor Stefan U. Egelhaaf (1963-2023), a pioneer in\nexperimental soft condensed matter physics.",
        "positive": "Superhydrophobicity of Auxetic Metamaterials: Superhydrophobic materials are often inspired by nature, whereas\nmetamaterials are engineered to have properties not usually found in naturally\noccurring materials. In both cases, the key that unlocks their unique\nproperties is structure. Here, we show that a negative Poisson's ratio\n(auxetic) mechanical metamaterial is capable of transforming into a unique type\nof superhydrophobic material. When stretched its surface has the\ncounterintuitive property that it also expands in the orthogonal lateral\ndirection. We model the change in the solid surface fraction as strain is\napplied and show it decreases as the space between solid elements of the\nauxetic lattice expands. This results in a unique dependence of the\nsuperhydrophobicity on strain. We construct experimental models illustrating\nthe relationship between different states of strain and superhydrophobicity as\nthe lattice structure transitions from an auxetic to a conventional (positive\nPoisson's ratio) one. The principles we have discovered offer a new approach to\ndesigning superhydrophobic materials for self-cleaning surfaces, droplet\ntransportation, droplet encapsulation and oil-water separation."
    },
    {
        "anchor": "Nucleation kinetics of vapor bubbles in a liquid with arbitrary\n  viscosity: The theory of vapor bubbles nucleation in single-component liquids developed\nin [J. Phys. Chem. B 116, 9445 (2012)] for the case of high viscosity (the\n(V,/rho,T)- theory) is extended to the case of arbitrary viscosity. For this\npurpose, Langevin's approach in the theory of Brownian motion, or Kramers'\nmodel of chemical reactions, is employed. The obtained expression for the\nbubbles nucleation rate is valid for arbitrary relations between the kinetic\nparameters controlling the nucleation process: viscosity, inertia of a liquid,\nthe rate of evaporation into a bubble and the rate of heat exchange between the\nbubble and ambient liquid. So, the presented theory together with the\n(V,/rho,T)- theory gives a complete description of the vapor-bubbles nucleation\nkinetics in one-component liquids. Limiting cases with respect to the mentioned\nparameters are considered, in particular, the low viscosity limit. It is shown\nthat the low- and high-viscosity nucleation rates differ from each other\nqualitatively and quantitatively. The possibility of application of the theory\nto cavitation in superfluid helium-4 is discussed.",
        "positive": "Scaling description of creep flow in amorphous solids: Amorphous solids such as coffee foam, toothpaste or mayonnaise display a\ntransient creep flow when a stress $\\Sigma$ is suddenly imposed. The associated\nstrain rate is commonly found to decay in time as $\\dot{\\gamma} \\sim t^{-\\nu}$,\nfollowed either by arrest or by a sudden fluidisation. Various empirical laws\nhave been suggested for the creep exponent $\\nu$ and fluidisation time $\\tau_f$\nin experimental and numerical studies. Here, we postulate that plastic flow is\ngoverned by the difference between $\\Sigma$ and the transient yield stress\n$\\Sigma_t(\\gamma)$ that characterises the stability of configurations visited\nby the system at strain $\\gamma$. Assuming the analyticity of\n$\\Sigma_t(\\gamma)$ allows us to predict $\\nu$ and asymptotic behaviours of\n$\\tau_f$ in terms of properties of stationary flows. We test successfully our\npredictions using elastoplastic models and published experimental results."
    },
    {
        "anchor": "Influence of the Anisometry of Magnetic Particles on the\n  Isotropic-Nematic Phase Transition: The influence of the shape anisotropy of magnetic particles on the\nisotropic-nematic phase transition was studied in ferronematics based on the\nnematic liquid crystal 4-(trans-4-n-hexylcyclohexyl)-isothiocyanato-benzene\n(6CHBT). The liquid crystal was doped with spherical or rod-like magnetic\nparticles of different size and volume concentrations. The phase transition\nfrom isotropic to nematic phase was observed by polarizing microscope as well\nas by capacitance measurements. The influence of the concentration and the\nshape anisotropy of the magnetic particles on the isotropic-nematic phase\ntransition in liquid crystal is demonstrated. The results are in a good\nagreement with recent theoretical predictions.",
        "positive": "Rheology of Wormlike Micellar Gels Formed By Long-Chained Zwitterionic\n  Surfactants: Long-chained surfactant solutions have found widespread use in the oil and\ngas industry due to a host of attractive properties. In this paper, we\ncharacterize one such commercially used viscoelastic surfactant that forms a\nwormlike micellar gel at room temperature and a viscoelastic solution at higher\ntemperatures. We probe both states by conducting linear and nonlinear\nrheological tests and analyze their behaviour under the framework of micellar\nrheology. Our study outlines departure from behaviour exhibited by more\nconventional micellar systems and uncovers interesting dynamics like\nshear-induced fracture and possible shear-banding in these materials. In doing\nso we provide a detailed understanding of a novel class of wormlike micellar\nsolutions"
    },
    {
        "anchor": "Gels under stress: the origins of delayed collapse: Attractive colloidal particles can form a disordered elastic solid or gel\nwhen quenched into a two-phase region, if the volume fraction is sufficiently\nlarge. When the interactions are comparable to thermal energies the\nstress-bearing network within the gel restructures over time as individual\nparticle bonds break and reform. Typically, under gravity such weak gels show a\nprolonged period of either no or very slow settling, followed by a sudden and\nrapid collapse - a phenomenon known as delayed collapse. The link between local\nbond breaking events and the macroscopic process of delayed collapse is not\nwell understood. Here we summarize the main features of delayed collapse and\ndiscuss the microscopic processes which cause it. We present a plausible model\nwhich connects the kinetics of bond breaking to gel collapse and test the model\nby exploring the effect of an applied external force on the stability of a gel.",
        "positive": "Velocity profile of granular flows inside silos and hoppers: We measure the flow of granular materials inside a quasi-two dimensional silo\nas it drains and compare the data with some existing models. The particles\ninside the silo are imaged and tracked with unprecedented resolution in both\nspace and time to obtain their velocity and diffusion properties. The data\nobtained by varying the orifice width and the hopper angle allows us to\nthoroughly test models of gravity driven flows inside these geometries. All of\nour measured velocity profiles are smooth and free of the shock-like\ndiscontinuities (\"rupture zones\") predicted by critical state soil mechanics.\nOn the other hand, we find that the simple Kinematic Model accurately captures\nthe mean velocity profile near the orifice, although it fails to describe the\nrapid transition to plug flow far away from the orifice. The measured diffusion\nlength $b$, the only free parameter in the model, is not constant as usually\nassumed, but increases with both the height above the orifice and the angle of\nthe hopper. We discuss improvements to the model to account for the\ndifferences. From our data, we also directly measure the diffusion of the\nparticles and find it to be significantly less than predicted by the Void\nModel, which provides the classical microscopic derivation of the Kinematic\nModel in terms of diffusing voids in the packing. However, the experimental\ndata is consistent with the recently proposed Spot Model, based on a simple\nmechanism for cooperative diffusion. Finally, we discuss the flow rate as a\nfunction of the orifice width and hopper angles. We find that the flow rate\nscales with the orifice size to the power of 1.5, consistent with dimensional\nanalysis. Interestingly, the flow rate increases when the funnel angle is\nincreased."
    },
    {
        "anchor": "Twist angle effects on the dynamic response of in-plane-switching liquid\n  crystal displays: Twist angle effect on the response time of in-plane-switching liquid crystal\ndisplays are analyzed. We propose a device configuration whose top and bottom\nboundary liquid crystal layers are symmetric to each other with respect to the\nelectric field direction. The analytical results of this device configuration\nindicate that the response time is improved at least 4X faster than that of a\nconventional in-plane-switching twisted-nematic mode and normal\nin-plane-switching mode.",
        "positive": "Measurement of higher-order stress-strain effects in granular materials\n  undergoing non-uniform deformation: Discrete element (DEM) simulations demonstrate that granular materials are\nnon-simple, meaning that the incremental stiffness of a granular assembly\ndepends on the gradients of the strain increment as well as on the strain\nincrement itself. In quasi-static simulations, two-dimensional granular\nassemblies were stiffer when the imposed deformation was non-uniform than for\nuniform deformation. The contacts between particles were modeled as\nlinear-frictional contacts with no contact moments. The results are interpreted\nin the context of a higher-order micro-polar continuum, which admits the\npossibility of higher-order stress and couple-stress. Although the behavior was\nnon-simple, no evidence was found for a couple-stress or an associated\nstiffness. The experimental results apply consistently to three particle shapes\n(circles, ovals, and a non-convex cluster shape), to assemblies of three sizes\n(ranging from 250 to 4000 particles), and at pre-peak and post-peak strains."
    },
    {
        "anchor": "Centrifugal deterministic lateral displacement separation system: This work investigates the migration of spherical particles of different\nsizes in a centrifuge-driven deterministic lateral displacement (c-DLD) device.\nSpecifically, we use a scaled-up model to study the motion of suspended\nparticles through a square array of cylindrical posts under the action of\ncentrifugation. Experiments show that separation of particles by size is\npossible depending on the orientation of the driving acceleration with respect\nto the array of posts (forcing angle). We focus on the fractionation of binary\nsuspensions and measure the separation resolution at the outlet of the device\nfor different forcing angles. We found excellent resolution at intermediate\nforcing angles, when large particles are locked to move at small migration\nangles but smaller particles follow the forcing angle more closely. Finally, we\nshow that reducing the initial concentration (number) of particles, approaching\nthe dilute limit of single particles, leads to increased resolution in the\nseparation.",
        "positive": "Oscillatory Instabilities in Frictional Granular Matter: Frictional granular matter is shown to be fundamentally different in its\nplastic responses to external strains from generic glasses and amorphous solids\nwithout friction. While regular glasses exhibit plastic instabilities due to a\nvanishing of a real eigenvalue of the Hessian matrix, frictional granular\nmaterials can exhibit a previously unnoticed additional mechanism for\ninstabilities, i.e. the appearance of a pair of complex eigenvalues leading to\noscillatory exponential growth of perturbations which are tamed by dynamical\nnonlinearities. This fundamental difference appears crucial for the\nunderstanding of plasticity and failure in frictional granular materials. The\npossible relevance to earthquake physics is discussed."
    },
    {
        "anchor": "Screened and Unscreened Phases in Sedimenting Suspensions: A coarse-grained stochastic hydrodynamical description of velocity and\nconcentration fluctuations in steadily sedimenting suspensions is constructed,\nand analyzed using self-consistent and renormalization group methods. We find\nthat there exists a dynamical, non-equilibrium phase transition from an\n\"unscreened\" phase in which we recover the Caflisch-Luke (R.E. Caflisch and\nJ.H.C. Luke, Phys. Fluids 28, 759 (1985)) divergence of the velocity variance\nto a \"screened\" phase where the velocity fluctuations have a finite correlation\nlength growing as $\\phi^{-1/3}$ where $\\phi$ is the particle volume fraction,\nin agreement with Segr\\`e et. al. (Phys. Rev. Lett. 79, 2574 (1997)) and the\nvelocity variance is independent of system size. Detailed predictions are made\nfor the correlation function in both phases and at the transition.",
        "positive": "Spontaneous curvature cancellation in forced thin sheets: In this paper we report numerically observed spontaneous vanishing of mean\ncurvature on a developable cone made by pushing a thin elastic sheet into a\ncircular container. We show that this feature is independent of thickness of\nthe sheet, the supporting radius and the amount of deflection. Several variants\nof developable cone are studied to examine the necessary conditions that lead\nto the vanishing of mean curvature. It is found that the presence of\nappropriate amount of radial stress is necessary. The developable cone geometry\nsomehow produces the right amount of radial stress to induce just enough radial\ncurvature to cancel the conical azimuthal curvature. In addition, the circular\nsymmetry of supporting container edge plays an important role. With an\nelliptical supporting edge, the radial curvature overcompensates the azimuthal\ncurvature near the minor axis and undercompensates near the major axis. Our\nnumerical finding is verified by a crude experiment using a reflective plastic\nsheet. We expect this finding to have broad importance in describing the\ngeneral geometrical properties of forced crumpling of thin sheets."
    },
    {
        "anchor": "On the mechanism of the flow of polymers: A non-Newtonian flow of a polymer melt is discussed. The description of the\nexponential decrease of the apparent viscosity by the well-known Eyring formula\nwith an activation energy reduction proportional to the shear stress does not\ntake into account specific features of the polymeric structure. We propose to\nmodify the description of the macromolecular flow mechanism by including\nconformational changes of the polymeric chains. The elasticity of a strained\npolymeric chain, having an entropy origin, can be the reason of the reduction\nof the activation energy for the transition of a molecular-kinetic unit of the\nchain into a new equilibrium state in the flow direction during the thermal\nfluctuation. In that case, the activation energy of the transition should\ndecrease by a value proportional to the reversible high-elastic component of\nthe shear deformation caused by the flow of the polymer.",
        "positive": "How boundary interactions dominate emergent driving of passive probes in\n  active matter: Colloidal probes immersed in an active bath have been found to behave like\nactive particles themselves. Here, we use coarse-grained simulations to\ninvestigate the mechanisms behind this behavior. We find that the active motion\nof the colloid cannot be simply attributed to the convective motion in the\nbath. Instead, the boundary of the probe contributes significantly to these\nadopted dynamics by causing active bath particles to spontaneously accumulate\nat the probe. This gathering of active bath particles then pushes the probe,\nthus promoting its emergent active-particle-like behavior. Furthermore, we find\nthat the dynamic properties of the probe depend on its size in a non-monotonic\nway, which further highlights the non-trivial interplay between probe and bath."
    },
    {
        "anchor": "Effective zero-thickness model for a conductive membrane driven by an\n  electric field: The behavior of a conductive membrane in a static (DC) electric field is\ninvestigated theoretically. An effective zero-thickness model is constructed\nbased on a Robin-type boundary condition for the electric potential at the\nmembrane, originally developed for electrochemical systems. Within such a\nframework, corrections to the elastic moduli of the membrane are obtained,\nwhich arise from charge accumulation in the Debye layers due to capacitive\neffects and electric currents through the membrane and can lead to an\nundulation instability of the membrane. The fluid flow surrounding the membrane\nis also calculated, which clarifies issues regarding these flows sharing many\nsimilarities with flows produced by induced charge electro-osmosis (ICEO).\nNon-equilibrium steady states of the membrane and of the fluid can be\neffectively described by this method. It is both simpler, due to the zero\nthickness approximation which is widely used in the literature on fluid\nmembranes, and more general than previous approaches. The predictions of this\nmodel are compared to recent experiments on supported membranes in an electric\nfield.",
        "positive": "Length scale dependent relaxation in colloidal gels: We use molecular dynamics computer simulations to investigate the relaxation\ndynamics of a simple model for a colloidal gel at a low volume fraction. We\nfind that due to the presence of the open spanning network this dynamics shows\nat low temperature a non-trivial dependence on the wave-vector which is very\ndifferent from the one observed in dense glass-forming liquids. At high wave\nvectors the relaxation is due to the fast cooperative motion of the branches of\nthe gel network, whereas at low wave vectors the overall rearrangements of the\nheterogeneous structure produce the relaxation process."
    },
    {
        "anchor": "Exploring pNIPAM Lyogels for SMART Reactors: Experimental Study on\n  Swelling Equilibria in Various Organic Solvents and Mixtures, Supported by\n  COSMO-RS Analysis: Stimuli-responsive lyogels are considered to be smart materials due to their\ncapability of undergoing significant macroscopic changes in response to\nexternal triggers. Due to their versatile and unique properties, smart lyogels\nexhibit great potential in various applications such as drug delivery or\nactuation processes. While Poly-N-isopropylacrylamide (pNIPAM) is widely known\nas a thermo-responsive material, it also shows significant solvent-responsive\nswelling behavior. As polar solvents induce strong swelling due to hydrogen\nbonding with the amide group, nonpolar solvents lead to significant shrinkage\nof the lyogels. The aim of this study is to investigate and to model this\nbehavior for future application in chemical or biochemical reactors. As a\ncurrent area of research, incorporating smart hydrogel technology into\n(bio-)chemical reactors facilitates the development of smart reactor systems.\nApplying thermodynamic modelling with the gE model COSMO-RS on the monomer or\noligomers of pNIPAM, the correlation between solvent-polymer interactions and\nthe degree of swelling can be observed. pNIPAM derivatives exhibit low\ninfinitive dilution activity coefficients (IDACs) in polar solvents with large\ndegrees of swelling, while displaying an increase of IDACs in nonpolar\nsolvents. Hydrogen bonds dominate the swelling behavior of lyogels not only in\npure solvents but also in mixtures of solvents with varying polarity. Even in\nmixtures containing high amounts of nonpolar solvents, large degrees of\nswelling were observed due to the uptake of the polar solvent in the lyogel\nmatrix. This effect can be observed in binary solvent mixtures but also in\nrepresentative mixtures along an esterification reaction with varying\ncarboxylic chain length of alcohol and carboxylic acids.",
        "positive": "Doubly-periodic instability pattern in a smectic A liquid crystal: We report the observation of a doubly-periodic surface defect-pattern in the\nliquid crystal 8CB, formed during the nematic--smectic A phase transition. The\npattern results from the antagonistic alignment of the 8CB molecules, which is\nhomeotropic at the surface and planar in the bulk of the sample cell. Within\nthe continuum Landau-deGennes theory of smectic liquid crystals, we find that\nthe long period (~10 \\mu m) of the pattern is given by the balance between the\nsurface anchoring and the elastic energy of curvature wall defects. The short\nperiod (~1 \\mu m) we attribute to a saddle-splay distortion, leading to a\nnon-zero Gaussian curvature and causing the curvature walls to break up."
    },
    {
        "anchor": "Two Parameters for Three Dimensional Wetting Transitions: Critical effects at complete and critical wetting in three dimensions are\nstudied using a coupled effective Hamiltonian H[s(y),\\ell]. The model is\nconstructed via a novel variational principle which ensures that the choice of\ncollective coordinate s(y) near the wall is optimal. We highlight the\nimportance of a new wetting parameter \\Omega(T) which has a strong influence on\ncritical properties and allows the status of long-standing Monte-Carlo\nsimulation controversies to be re-examined.",
        "positive": "Direct test of defect mediated laser induced melting theory for two\n  dimensional solids: We investigate by direct numerical solution of appropriate renormalization\nflow equations, the validity of a recent dislocation unbinding theory for laser\ninduced freezing/melting in two dimensions. The bare elastic moduli and\ndislocation fugacities which are inputs to the flow equations are obtained for\nthree different 2-d systems (hard disk, inverse $12^{th}$ power and the\nDerjaguin-Landau-Verwey-Overbeek potentials) from a restricted Monte Carlo\nsimulation sampling only configurations {\\em without} dislocations. We conclude\nthat (a) the flow equations need to be correct at least up to third order in\ndefect fugacity to reproduce meaningful results, (b) there is excellent\nquantitative agreement between our results and earlier conventional Monte Carlo\nsimulations for the hard disk system and (c) while the qualitative form of the\nphase diagram is reproduced for systems with soft potentials there is some\nquantitative discrepancy which we explain."
    },
    {
        "anchor": "Conformations of closed DNA: We examine the conformations of a model for a short segment of closed DNA.\nThe molecule is represented as a cylindrically symmetric elastic rod with a\nconstraint corresponding to a specification of the linking number. We obtain\nanalytic expressions leading to the spatial configuration of a family of\nsolutions representing distortions that interpolate between the circular form\nof DNA and a figure-eight form that represents the onset of interwinding. We\nare also able to generate knotted loops. We suggest ways to use our approach to\nproduce other configurations relevant to studies of DNA structure. The\nstability of the distorted configurations is assessed, along with the effects\nof fluctuations on the free energy of the various configurations.",
        "positive": "Hydrodynamic Crossovers in Surface-Directed Spinodal Decomposition and\n  Surface Enrichment: We present comprehensive molecular dynamics (MD) results for the kinetics of\nsurface-directed spinodal decomposition (SDSD) and surface enrichment (SE) in\nbinary mixtures at wetting surfaces. We study the surface morphology and the\ngrowth dynamics of the wetting and enrichment layers. The growth law for the\nthickness of these layers shows a crossover from a diffusive regime to a\nhydrodynamic regime. We provide phenomenological arguments to understand this\ncrossover."
    },
    {
        "anchor": "Origin of the anomalous heat current in collisional granular fluids: We present a heuristic explanation for the anomalous\n(density-gradient-dependent) heat current in collisional granular fluids.\nInelastic grain collisions lead to highly non-equilibrium states which are\ncharacterized by large spatial gradients and/or temporal variations in the\ngranular temperature. It is argued that the heat current in such\nnon-equilibrium states is driven by the temperature gradient averaged over the\ntypical collision time and/or mean free path. Due to the density dependence of\nthe inelastic energy loss, the nonlocal averaging of the temperature gradient\nleads to an effective dependence of the heat current upon the density gradient.",
        "positive": "Average Structures of a Single Knotted Ring Polymer: Two types of average structures of a single knotted ring polymer are studied\nby Brownian dynamics simulations. For a ring polymer with N segments, its\nstructure is represented by a 3N -dimensional conformation vector consisting of\nthe Cartesian coordinates of the segment positions relative to the center of\nmass of the ring polymer. The average structure is given by the average\nconformation vector, which is self-consistently defined as the average of the\nconformation vectors obtained from a simulation each of which is rotated to\nminimize its distance from the average conformation vector. From each\nconformation vector sampled in a simulation, 2N conformation vectors are\ngenerated by changing the numbering of the segments. Among the 2N conformation\nvectors, the one closest to the average conformation vector is used for one\ntype of the average structure. The other type of the averages structure uses\nall the conformation vectors generated from those sampled in a simulation. In\nthecase of the former average structure, the knotted part of the average\nstructure is delocalized for small N and becomes localized as N is increased.\nIn the case of the latter average structure, the average structure changes from\na double loop structure for small N to a single loop structure for large N,\nwhich indicates the localization-delocalization transition of the knotted part."
    },
    {
        "anchor": "Simulational studies of axial granular segregation in a rotating\n  cylinder: Discrete particle simulation methods have been used to study axial\nsegregation in a horizontal rotating cylinder that is partially filled with a\nmixture of two different kinds of granular particles. Under suitable conditions\nsegregation was found to occur, with the particles separating into a series of\nbands perpendicular to the axis. In certain cases the band structure exhibited\ntime-dependent behavior, including band formation, merging and motion along the\naxis, all corresponding to phenomena that arise experimentally. In order to\nexamine how the many parameters specifying the problem affect the segregation\nprocess, simulation runs were carried out using a variety of parameter\nsettings, including combinations of friction coefficients not realizable\nexperimentally. Both segregation and desegregation (mixing) were investigated,\nand cylinders with both explicit end caps and periodic ends were used to help\nisolate the causes of segregation.",
        "positive": "Modeling the combined effect of surface roughness and shear rate on slip\n  flow of simple fluids: Molecular dynamics (MD) and continuum simulations are carried out to\ninvestigate the influence of shear rate and surface roughness on slip flow of a\nNewtonian fluid. For weak wall-fluid interaction energy, the nonlinear\nshear-rate dependence of the intrinsic slip length in the flow over an\natomically flat surface is computed by MD simulations. We describe laminar flow\naway from a curved boundary by means of the effective slip length defined with\nrespect to the mean height of the surface roughness. Both the magnitude of the\neffective slip length and the slope of its rate-dependence are significantly\nreduced in the presence of periodic surface roughness. We then numerically\nsolve the Navier-Stokes equation for the flow over the rough surface using the\nrate-dependent intrinsic slip length as a local boundary condition. Continuum\nsimulations reproduce the behavior of the effective slip length obtained from\nMD simulations at low shear rates. The slight discrepancy between MD and\ncontinuum results at high shear rates is explained by examination of the local\nvelocity profiles and the pressure distribution along the wavy surface. We\nfound that in the region where the curved boundary faces the mainstream flow,\nthe local slip is suppressed due to the increase in pressure. The results of\nthe comparative analysis can potentially lead to the development of an\nefficient algorithm for modeling rate-dependent slip flows over rough surfaces."
    },
    {
        "anchor": "The generalised Mooney space for modelling the response of rubber-like\n  materials: Soft materials such as rubbers, silicones, gels and biological tissues have a\nnonlinear response to large deformations, a phenomenon which in principle can\nbe captured by hyperelastic models. The suitability of a candidate hyperelastic\nstrain energy function is then determined by comparing its predicted response\nto the data gleaned from tests and adjusting the material parameters to get a\ngood fit, an exercise which can be deceptive because of nonlinearity. Here we\npropose to generalise the approach of Rivlin and Saunders [Phil Trans A 243\n(1951) 251-288] who, instead of reporting the data as stress against stretch,\nmanipulated these measures to create the 'Mooney plot', where the Mooney-Rivlin\nmodel is expected to produce a linear fit. We show that extending this idea to\nother models and modes of deformation (tension, shear, torsion, etc.) is\nadvantageous, not only (a) for the fitting procedure, but also to (b) delineate\ntrends in the deformation which are not obvious from the raw data (and may be\ninterpreted in terms of micro-, meso-, and macro-structures) and (c) obtain a\nbounded condition number \\k{appa} over the whole range of deformation; a\nrobustness which is lacking in other plots and spaces.",
        "positive": "Kink instability of a highly deformable elastic cylinder: When a soft elastic cylinder is bent beyond a critical radius of curvature, a\nsharp fold in the form of a kink appears at its inner side while the outer side\nremains smooth. The critical radius increases linearly with the diameter of the\ncylinder while remaining independent of its elastic modulus, although, its\nmaximum deflection at the location of the kink depends on both the diameter and\nthe modulus of the cylinders. Experiments are done also with annular cylinders\nof varying wall thickness which exhibits both the kinking and the ovalization\nof the cross-section. The kinking phenomenon appears to occur by extreme\nlocalization of curvature at the inner side of a post-buckled cylinder."
    },
    {
        "anchor": "Atomistic mechanism of physical ageing in glassy materials: Using molecular simulations, we identify microscopic relaxation events of\nindividual particles in ageing structural glasses, and determine the full\ndistribution of relaxation times. We find that the memory of the waiting time\n$t_w$ elapsed since the quench extends only up to the first relaxation event,\nwhile the distribution of all subsequent relaxation times (persistence times)\nfollows a power law completely independent of history. Our results are in\nremarkable agreement with the well known phenomenological trap model of ageing.\nA continuous time random walk (CTRW) parametrized with the atomistic\ndistributions captures the entire bulk diffusion behavior and explains the\napparent scaling of the relaxation dynamics with $t_w$ during ageing, as well\nas observed deviations from perfect scaling.",
        "positive": "Bose-Fermi variational theory of the BEC-Tonks crossover: A number-conserving hybrid Bose-Fermi variational theory is developed and\napplied to investigation of the BEC-Tonks gas crossover in toroidal and long\ncylindrical traps of high aspect ratio, where strong many-body correlations and\ncondensate depletion occur."
    },
    {
        "anchor": "Role of Non-Equilibrium Conformations on Driven Polymer Translocation: One of the major theoretical methods in understanding polymer translocation\nthrough a nanopore is the Fokker-Planck formalism based on the assumption of\nquasi-equilibrium of polymer conformations. The criterion for applicability of\nthe quasi-equilibrium approximation for polymer translocation is that the\naverage translocation time per Kuhn segment, $\\langle \\tau \\rangle/N_K$ is\nlonger than the relaxation time $\\tau_0$ of the polymer. Towards an\nunderstanding of conditions that would satisfy this criterion, we have\nperformed coarse-grained three dimensional Langevin dynamics and multi-particle\ncollision dynamics simulations. We have studied the role of initial\nconformations of a polyelectrolyte chain (which were artificially generated\nwith a flow field) on the kinetics of its translocation across a nanopore under\nthe action of an externally applied transmembrane voltage $V$ (in the absence\nof the initial flow field). Stretched (out-of-equilibrium) polyelectrolyte\nchain conformations are deliberately and systematically generated and used as\ninitial conformations in translocation simulations. Independent simulations are\nperformed to study the relaxation behavior of these stretched chains and a\ncomparison is made between the relaxation timescale and the mean translocation\ntime ($\\langle \\tau \\rangle$). For such artificially stretched initial states,\n$\\langle \\tau \\rangle/N_K < \\tau_0$, demonstrating the inapplicability of the\nquasi-equilibrium approximation. Nevertheless, we observe a scaling of $\\langle\n\\tau \\rangle \\sim 1/V$ over the entire range of chain stretching studied, in\nagreement with the predictions of the Fokker-Planck model. On the other hand,\nfor realistic situations where initial artificially imposed flow field is\nabsent, a comparison of experimental data reported in the literature with the\ntheory",
        "positive": "Discrete symmetries control mechanical response in parallelogram-based\n  origami: Geometric compatibility constraints dictate the mechanical response of soft\nsystems that can be utilized for the design of mechanical metamaterials such as\nthe negative Poisson ratio Miura-ori origami crease pattern. Here, we develop a\nformalism for linear compatibility that enables explicit investigation of the\ninterplay between geometric symmetries and functionality in origami crease\npatterns. We apply this formalism to a particular class of periodic crease\npatterns with unit cells composed of four arbitrary parallelogram faces and\nestablish that their mechanical response is characterized by an anticommuting\nsymmetry. In particular, we show that the modes are eigenstates of this\nsymmetry operator and that these modes are simultaneously diagonalizable with\nthe symmetric strain operator and the antisymmetric curvature operator. This\nfeature reveals that the anticommuting symmetry defines an equivalence class of\ncrease pattern geometries which possess equal and opposite in-plane and\nout-of-plane Poisson's ratios."
    },
    {
        "anchor": "Effect of particle stiffness and surface properties on the nonlinear\n  viscoelasticity of dense microgel suspensions: Particle surface chemistry and internal softness are two fundamental\nparameters in governing the mechanical properties of dense colloidal\nsuspensions, dictating structure and flow, therefore of interest from materials\nfabrication to processing. Here, we modulate softness by tuning the crosslinker\ncontent of poly(N-isopropylacrylamide) microgels, and we adjust their surface\nproperties by co-polymerization with polyethylene glycol (PEG) chains,\ncontrolling adhesion, friction and fuzziness. We investigate the distinct\neffects of these parameters on the entire mechanical response from\nrestructuring to complete fluidization of jammed samples at varying packing\nfractions under large-amplitude oscillatory shear experiments, and we\ncomplement rheological data with colloidal-probe atomic force microscopy to\nunravel variations in the particles' surface properties. We find that surface\nproperties play a fundamental role at smaller packings; decreasing adhesion and\nfriction at contact causes the samples to yield and fluidify in a lower\ndeformation range. Instead, increasing softness or fuzziness has a similar\neffect at ultra-high densities, making suspensions able to better adapt to the\napplied shear and reach complete fluidization over a larger deformation range.\nThese findings shed new light on the single-particle parameters governing the\nmechanical response of dense suspensions subjected to deformation, offering\nsynthetic approaches to design materials with tailored mechanical properties.",
        "positive": "Demonstration of the effect of stirring on nucleation from experiments\n  on the International Space Station using the ISS-EML facility: The effect of fluid flow on crystal nucleation in supercooled liquids is not\nwell understood. The variable density and temperature gradients in the liquid\nmake it difficult to study this under terrestrial gravity conditions.\nNucleation experiments were therefore made in a microgravity environment using\nthe Electromagnetic Levitation facility on the International Space Station on a\nbulk glass-forming Zr57Cu15.4Ni12.6Al10Nb5 (Vit106), as well as Cu50Zr50 and\nthe quasicrystal-forming Ti39.5Zr39.5Ni21 liquids. The maximum supercooling\ntemperatures for each alloy were measured as a function of controlled stirring\nby applying various combinations of radio frequency positioner and heater\nvoltages to the water-cooled copper coils. The flow patterns were simulated\nfrom the known parameters for the coil and the levitated samples. The maximum\nnucleation temperatures increased systematically with increased fluid flow in\nthe liquids for Vit106, but stayed nearly unchanged for the other two. These\nresults are consistent with the predictions from the coupled-flux model for\nnucleation."
    },
    {
        "anchor": "Molecular view of the Rayleigh-Taylor instability in compressible\n  Brownian fluids: The onset of the Rayleigh-Taylor instability is studied a compressible\nBrownian Yukawa fluid mixture on the ``molecular'' length and time scales of\nthe individual particles. As a model, a two-dimensional phase-separated\nsymmetric binary mixture of colloidal particles of type $A$ and $B$ with a\nfluid-fluid interface separating an $A$-rich phase from a $B$-rich phase is\ninvestigated by Brownian computer simulations when brought into non-equilibrium\nvia a constant external driving field which acts differently on the different\nparticles and perpendicular to the interface. Two different scenarios are\nobserved which occur either for high or for low interfacial free energies as\ncompared to the driving force. In the first scenario for high interfacial\ntension, the critical wavelength $\\lambda_c$ of the unstable interface modes is\nin good agreement with the classical Rayleigh-Taylor formula provided\ndynamically rescaled values for the interfacial tension are used. The\nwavelength $\\lambda_{c}$ increases with time representing a self-healing effect\nof the interface due to a local density increase near the interface. The\nRayleigh-Taylor formula is confirmed even if $\\lambda_c$ is of the order of a\nmolecular correlation length. In the second scenario for very large driving\nforces as compared to the interfacial line tensions, on the other hand, the\nparticle penetrate easily the interface by the driving field and form\nmicroscopic lanes with a width different from the predictions of the classical\nRayleigh-Taylor formula.",
        "positive": "Microrheology of active suspensions: We study the microrheology of active suspensions through direct hydrodynamic\nsimulations using model pusher-like microswimmers. We demonstrate that the\nfriction coefficient of a probe particle is notably reduced by hydrodynamic\ninteractions (HIs) among a moving probe and the swimmers. When a swimmer\napproaches a probe from the rear (front) side, the repulsive HIs between them\nare weakened (intensified), which results in a slight front rear asymmetry in\nswimmer orientation distribution around the probe, creating a significant\nadditional net driving force acting on the probe from the rear side. The\npresent drag-reduction mechanism qualitatively differs from that of the\nviscosity-reduction observed in sheared bulk systems and depends on probing\ndetails. This study provides insights into our fundamental knowledge of\nhydrodynamic effects in active suspensions and serves as a practical example\nilluminating distinctions between micro- and macrorheology measurements."
    },
    {
        "anchor": "Revisiting the fragile-to-strong crossover in metallic glass-forming\n  liquids: application to Cu$_x$Zr$_x$Al$_{100-2x}$: The fragile-to-strong crossover seems to be a general feature of metallic\nglass-forming liquids. Here, we study the behavior of shear viscosity,\ndiffusion coefficient and vibrational density of states for\nCu$_\\text{x}$Zr$_\\text{x}$Al$_{\\text{100-2x}}$ alloy through molecular dynamics\nsimulations. The results reveal that the fragile-to-strong temperature\n(T$_\\text{fs}$) and the glass transition temperature (T$_\\text{g}$) increase as\nthe aluminum content becomes larger. The inverse of the diffusion coefficient\nas a function of temperature exhibits a dynamical crossover in the vicinity of\nT$_\\text{g}$, at a much lower temperature than that predicted by nearly all\nprevious studies. At the temperature in which the dynamical crossover occurs\ndetermined by the inverse of the diffusion coefficient, we found an excess of\nvibrational states at low frequencies, resembling a pronounced peak in the\nreduced vibrational density of states characteristic of a strong liquid.\nFinally, the behavior of the shear viscosity as a function of reduced\ntemperature (T$_\\text{g}$/T) also shows that, besides the fragile-to-strong\ncrossover nearby T$_\\text{g}$, another dynamical crossover is present near the\nonset of the supercooled regime.",
        "positive": "Shear flow of non-Brownian suspensions close to jamming: The dynamical mechanisms controlling the rheology of dense suspensions close\nto jamming are investigated numerically, using simplified models for the\nrelevant dissipative forces. We show that the velocity fluctuations control the\ndissipation rate and therefore the effective viscosity of the suspension. These\nfluctuations are similar in quasi-static simulations and for finite strain rate\ncalculations with various damping schemes. We conclude that the statistical\nproperties of grain trajectories -- in particular the critical exponent of\nvelocity fluctuations with respect to volume fraction \\phi -- only weakly\ndepend on the dissipation mechanism. Rather they are determined by steric\neffects, which are the main driving forces in the quasistatic simulations. The\ncritical exponent of the suspension viscosity with respect to \\phi can then be\ndeduced, and is consistent with experimental data."
    },
    {
        "anchor": "Geometry dependence of the clogging transition in tilted hoppers: We report the effect of system geometry on the clogging of granular material\nflowing out of flat-bottomed hoppers with variable aperture size D. For such\nsystems, there exists a critical aperture size Dc at which there is a\ndivergence in the time for a flow to clog. To better understand the origins of\nDc, we perturb the system by tilting the hopper an angle Q and mapping out a\nclogging phase diagram as a function of Q and D. The clogging transition\ndemarcates the boundary between the freely-flowing (large D, small Q) and\nclogging (small D, large Q) regimes. We investigate how the system geometry\naffects Dc by mapping out this phase diagram for hoppers with either a circular\nhole or a rectangular narrow slit. Additionally, we vary the grain shape,\ninvestigating smooth spheres (glass beads), compact angular grains (beach\nsand), disk-like grains (lentils), and rod-like grains (rice). We find that the\nvalue of Dc grows with increasing Q, diverging at pi-Qr where Qr is the angle\nof repose. For circular apertures, the shape of the clogging transition is the\nsame for all grain types. However, this is not the case for the narrow slit\napertures, where the rate of growth of the critical hole size with tilt angle\ndepends on the material.",
        "positive": "Scaling out the density dependence of the $\u03b1$ relaxation in\n  glassforming polymers: We show that the density and temperature dependences of the\n$\\alpha$-relaxation time of several glassforming polymers can be described\nthrough a single scaling variable $X=e(\\rho)/T$, where $e(\\rho)$ is well fitted\nby a power law $\\rho^x$, $x$ being a species-specific parameter. This implies\nthat ``fragility'' is an intrinsic, density-independent property of a\nglassformer characterizing its super-Arrhenius slowing down of relaxations, and\nit leads us to propose a modification of the celebrated Angell plot."
    },
    {
        "anchor": "Mesoscopic non-equilibrium thermodynamics approach to the dynamics of\n  polymers: We present a general formalism able to derive the kinetic equations of\npolymer dynamics. It is based on the application of nonequilibrium\nthermodynamics to analyze the irreversible processes taking place in the\nconformational space of the macromolecules. The Smoluchowski equation results\nfrom the analysis of the underlying diffusion process in that space within the\nscheme of nonequilibrium thermodynamics. We apply the method to different\nsituations, concerning flexible, semiflexible and rod-like polymers and to the\ncase of more concentrated solutions in which interactions become important.",
        "positive": "A simple model for dynamic heterogeneity in glass-forming liquids: Liquids near the glass transition exhibit dynamical heterogeneity, i.e. local\nrelaxation rates fluctuate strongly over space and time. Here we introduce a\nsimple continuum model that allows for quantitative predictions for the\ncorrelators describing these fluctuations. We find remarkable agreement of the\nmodel predictions for the dynamic susceptibility $\\chi_4(t)$ with numerical\nresults for a binary hard-sphere liquid and for a Kob-Andersen Lennard-Jones\nmixture. Under this model, the lifetime $\\tau_{\\rm ex}$ of the heterogeneities\nhas little effect on the position $t = t_4 \\sim \\tau_{\\alpha}$ of the peak of\n$\\chi_4(t)$, but it controls the decay of $\\chi_4(t)$ after the peak, and we\nshow how to estimate it from this decay."
    },
    {
        "anchor": "Molecular Simulation of Thermo-osmotic slip: Thermo-osmotic slip -- the flow induced by a thermal gradient along a surface\n-- is a well-known phenomenon, but curiously there is a lack of robust\nmolecular-simulation techniques to predict its magnitude. Here, we compare\nthree different molecular simulation techniques to compute the thermo-osmotic\nslip at a simple solid-fluid interface. Although we do not expect the different\napproaches to be in perfect agreement, we find that the differences are barely\nsignificant for a range of different physical conditions, suggesting that\npractical molecular simulations of thermo-osmotic slip are feasible.",
        "positive": "A Novel Chiral Phase of Achiral Hard Triangles and an Entropy-Driven\n  Demixing of Enantiomers: We investigate the phase behavior of a system of hard equilateral and\nright-angled triangles in two dimensions using Monte Carlo simulations. Hard\nequilateral triangles undergo a continuous isotropic-triatic liquid crystal\nphase transition at packing fraction $\\phi=0.7$. Similarly, hard right-angled\nisosceles triangles exhibit a first-order phase transition from an isotropic\nfluid phase to a rhombic liquid crystal phase with a coexistence region $\\phi\n\\in \\left[0.733,0.782\\right]$. Both these liquid crystal phases undergo a\ncontinuous phase transition to their respective close-packed crystal structures\nat high pressures. Although the particles and their close-packed crystals are\nboth achiral, the solid phases of equilateral and right-angled triangles\nexhibit spontaneous chiral symmetry breaking at sufficiently high packing\nfractions. The colloidal triangles rotate either in clockwise or anti-clockwise\ndirection with respect to one of the lattice vectors for packing fractions\nhigher than $\\phi_\\chi$. As a consequence, these triangles spontaneously form a\nregular lattice of left- or right-handed chiral holes which are surrounded by\nsix triangles in the case of equilateral triangles and four or eight triangles\nfor right-angled triangles. Moreover, our simulations show a spontaneous\nentropy-driven demixing transition of the right- and left-handed \"enantiomers\"."
    },
    {
        "anchor": "Generalized Dynamics for Second Kind of Soft-Matter Quasicrystals: The equations of generalized dynamics of the first kind of soft-matter\nquasicrystals are derived and given in the previous report, we now introduce\nthe equations of the dynamics for the second kind of quasicrystals in soft\nmatter.",
        "positive": "Relationship between Structure, Entropy and Diffusivity in Water and\n  Water-like Liquids: Anomalous behaviour of the excess entropy ($S_e$) and the associated scaling\nrelationship with diffusivity are compared in liquids with very different\nunderlying interactions but similar water-like anomalies: water (SPC/E and\nTIP3P models), tetrahedral ionic melts (SiO$_2$ and BeF$_2$) and a fluid with\ncore-softened, two-scale ramp (2SRP) interactions. We demonstrate the presence\nof an excess entropy anomaly in the two water models. Using length and energy\nscales appropriate for onset of anomalous behaviour, the density range of the\nexcess entropy anomaly is shown to be much narrower in water than in ionic\nmelts or the 2SRP fluid. While the reduced diffusivities ($D^*$) conform to the\nexcess entropy scaling relation, $D^* =A\\exp (\\alpha S_e)$ for all the systems\n(Y. Rosenfeld, Phys. Rev. A {\\bf 1977}, {\\it 15}, 2545), the exponential\nscaling parameter, $\\alpha$, shows a small isochore-dependence in the case of\nwater. Replacing $S_e$ by pair correlation-based approximants accentuates the\nisochore-dependence of the diffusivity scaling. Isochores with similar\ndiffusivity scaling parameters are shown to have the temperature dependence of\nthe corresponding entropic contribution. The relationship between diffusivity,\nexcess entropy and pair correlation approximants to the excess entropy are very\nsimilar in all the tetrahedral liquids."
    },
    {
        "anchor": "Granular Collapse as a Percolation Transition: Inelastic collapse is found in a two-dimensional system of inelastic hard\ndisks confined between two walls which act as an energy source. As the\ncoefficient of restitution is lowered, there is a transition between a state\ncontaining small collapsed clusters and a state dominated by a large collapsed\ncluster. The transition is analogous to that of a percolation transition. At\nthe transition the number of clusters n_s of size s scales as $n_s \\sim\ns^{-\\tau}$ with $\\tau \\approx 2.7$.",
        "positive": "Theory and simulation of macromolecular crowding effects on protein\n  folding stability and kinetics: We investigate the effect of macromolecular crowding on protein folding,\nusing purely repulsive crowding particles and a self-organizing polymer model\nof protein folding. We find that the thermodynamics of folding for typical\nalpha-, beta- and alpha/beta-proteins are well described by an adaptation of\nthe scaled particle theory (SPT). In this approach, the native state,\ntransition state, and the unfolded protein are treated as effective hard\nspheres with radii approximately independent of the size and concentration of\nthe crowders. The same model predicts the effect of crowding on the folding\nbarrier and therefore refolding rates with no adjustable parameters. A simple\nextension of the SPT model, assuming additivity, can also describe the behavior\nof mixtures of crowding particles."
    },
    {
        "anchor": "Fore-aft clearance controls how three-dimensional confinement affects\n  micropropulsion: Systems of active particles are often affected by confinement due to nearby\nboundaries. Recently, there has been interest in the effect of confinement by\ncomplex three dimensional geometries, as might occur in structured environments\nsuch as porous media, foams, gels, or biological tissues and ducts. The effects\nof confinement for particles moving along boundaries has been extensively\nstudied, but in three dimensions active particles move not only parallel to\nboundaries, but also towards or away from boundaries. The consequences of this\nfore-aft clearance is less well understood. Swimmers that actively remodel\ntheir environment create an ideal situation to study the effect of clearance,\nsince they maintain a steady clearance while translating. By numerically\nstudying the locomotion of the bacterium Helicobacter pylori, which de-gels\nsurrounding gastric mucus to make a co-moving pocket of fluid around itself, we\nshow that the effect of three-dimensional confinement is controlled by\nclearance, rather than distance from a parallel boundary. Analytical\ncalculations show that the effect of clearance can be understood in terms of\nflow structures, such as the generic pusher and puller flows of active\nparticles, indicating that our results should apply to a wide range of confined\nactive particles.",
        "positive": "Slow Dynamics Near Jamming: Static and dynamic properties of two-dimensional bidisperse dissipative\nparticles are numerically studied near the jamming transition. We investigate\nthe dependency of the critical scaling on the ratio of the different diameters\nand find a new scaling of the maximum overlap (not consistent with the scaling\nof the mean overlap). The ratio of kinetic and potential energies drastically\nslows down near the jamming transition, i.e. the relaxation time diverges at\nthe jamming point."
    },
    {
        "anchor": "Effect of Chain Stiffness on the Structure of Single-Chain Polymer\n  Nanoparticles: Polymeric single-chain nanoparticles (SCNPs) are soft nano-objects\nsynthesized by purely intramolecular cross-linking of single polymer chains. By\nmeans of computer simulations, we investigate the conformational properties of\nSCNPs as a function of the bending stiffness of their linear polymer\nprecursors. We investigate a broad range of characteristic ratios from the\nfully flexible case to those typical of bulky synthetic polymers. Increasing\nstiffness hinders bonding of groups separated by short contour distances and\nincreases looping over longer distances, leading to more compact nanoparticles\nwith a structure of highly interconnected loops. This feature is reflected in a\ncrossover in the scaling behaviour of several structural observables. The\nscaling exponents change from those characteristic for Gaussian chains or rings\nin $\\theta$-solvents in the fully flexible limit, to values resembling fractal\nor `crumpled' globular behaviour for very stiff SCNPs. We characterize domains\nin the SCNPs. These are weakly deformable regions that can be seen as\ndisordered analogues of domains in disordered proteins. Increasing stiffness\nleads to bigger and less deformable domains. Surprisingly, the scaling\nbehaviour of the domains is in all cases similar to that of Gaussian chains or\nrings, irrespective of the stiffness and degree of cross-linking. It is the\nspatial arrangement of the domains which determines the global structure of the\nSCNP (sparse Gaussian-like object or crumpled globule). Since intramolecular\nstiffness can be varied through the specific chemistry of the precursor or by\nintroducing bulky side groups in its backbone, our results propose a new\nstrategy to tune the global structure of SCNPs.",
        "positive": "Consistent coarse-graining strategy for polymer solutions in the thermal\n  crossover from Good to Theta solvent: We extend our previously developed coarse-graining strategy for linear\npolymers with a tunable number n of effective atoms (blobs) per chain [D'Adamo\net al., J. Chem. Phys. 137, 4901 (2012)] to polymer systems in thermal\ncrossover between the good-solvent and the Theta regimes. We consider the\nthermal crossover in the region in which tricritical effects can be neglected,\ni.e. not too close to the Theta point, for a wide range of chain volume\nfractions Phi=c/c* (c* is the overlap concentration), up to Phi=30. Scaling\ncrossover functions for global properties of the solution are obtained by\nMonte-Carlo simulations of the Domb-Joyce model. They provide the input data to\ndevelop a minimal coarse-grained model with four blobs per chain. As in the\ngood-solvent case, the coarse-grained model potentials are derived at zero\ndensity, thus avoiding the inconsistencies related to the use of\nstate-dependent potentials. We find that the coarse-grained model reproduces\nthe properties of the underlying system up to some reduced density which\nincreases when lowering the temperature towards the Theta state. Close to the\nlower-temperature crossover boundary, the tetramer model is accurate at least\nup to Phi<10, while near the good-solvent regime reasonably accurate results\nare obtained up to Phi<2. The density region in which the coarse-grained model\nis predictive can be enlarged by developing coarse-grained models with more\nblobs per chain. We extend the strategy used in the good-solvent case to the\ncrossover regime. This requires a proper treatment of the length rescalings as\nbefore, but also a proper temperature redefinition as the number of blobs is\nincreased. The case n=10 is investigated. Comparison with full-monomer results\nshows that the density region in which accurate predictions can be obtained is\nsignificantly wider than that corresponding to the n=4 case."
    },
    {
        "anchor": "Phase behaviour and structure of a superionic liquid in nonpolarized\n  nanoconfinement: The ion-ion interactions become exponentially screened for ions confined in\nultranarrow metallic pores. To study the phase behaviour of an assembly of such\nions, called a superionic liquid, we develop a statistical theory formulated on\nbipartite lattices, which allows an analytical solution within the\nBethe-lattice approach. Our solution predicts the existence of ordered and\ndisordered phases in which ions form a crystal-like structure and a homogeneous\nmixture, respectively. The transition between these two phases can potentially\nbe first or second order, depending on the ion diameter, degree of confinement\nand pore ionophobicity. We supplement our analytical results by\nthree-dimensional off-lattice Monte Carlo simulations of an ionic liquid in\nslit nanopores. The simulations predict formation of ionic clusters and ordered\nsnake-like patterns, leading to characteristic close-standing peaks in the\ncation-cation and anion-anion radial distribution functions.",
        "positive": "Organization of fast and slow chromatin revealed by single-nucleosome\n  dynamics: Understanding chromatin organization and dynamics is important since they\ncrucially affect DNA functions. In this study, we investigate chromatin\ndynamics by statistically analyzing single-nucleosome movement in living human\ncells. Bi-modal nature of the mean squared displacement distribution of\nnucleosomes allows for a natural categorization of the nucleosomes as fast and\nslow. Analyses of the nucleosome-nucleosome correlation functions within these\ncategories along with the density of vibrational modes show that the\nnucleosomes form dynamically correlated fluid regions, i.e., dynamic domains of\nfast and slow nucleosomes. Perturbed nucleosome dynamics by global histone\nacetylation or cohesin inactivation indicate that nucleosome-nucleosome\ninteractions along with tethering of chromatin chains organize nucleosomes into\nfast and slow dynamic domains. A simple polymer model is introduced, which\nshows the consistency of this dynamic domain picture. Statistical analyses of\nsingle-nucleosome movement provide rich information on how chromatin is\ndynamically organized in a fluid manner in living cells."
    },
    {
        "anchor": "Exclusion zone phenomena in water -- a critical review of experimental\n  findings and theories: The existence of the exclusion zone (EZ), a layer of water in which plastic\nmicrospheres are repelled from hydrophilic surfaces, has now been independently\ndemonstrated by several groups. A better understanding of the mechanisms which\ngenerate EZs would help with understanding the possible importance of EZs in\nbiology and in engineering applications such as filtration and microfluidics.\nHere we review the experimental evidence for EZ phenomena in water and the\nmajor theories that have been proposed. We review experimental results from\nbirefringence, neutron radiography, nuclear magnetic resonance, and other\nstudies. Pollack and others have theorized that water in the EZ exists has a\ndifferent structure than bulk water, and that this accounts for the EZ. We\npresent several alternative explanations for EZs and argue that Schurr's theory\nbased on diffusiophoresis presents a compelling alternative explanation for the\ncore EZ phenomenon. Among other things, Schurr's theory makes predictions about\nthe growth of the EZ with time which have been confirmed by Florea et al. and\nothers. We also touch on several possible confounding factors that make\nexperimentation on EZs difficult, such as charged surface groups, dissolved\nsolutes, and adsorbed nanobubbles.",
        "positive": "Influence of particle composition and thermal cycling on bijel formation: Colloidal particles with appropriate wetting properties can become very\nstrongly trapped at an interface between two immiscible fluids. We have\nharnessed this phenomenon to create a new class of soft materials with\nintriguing and potentially useful characteristics. The material is known as a\nbijel: bicontinuous interfacially-jammed emulsion gel. It is a\ncolloid-stabilized emulsion with fluid-bicontinuous domains. The potential to\ncreate these gels was first predicted using computer simulations.\nExperimentally we use mixtures of water and 2,6-lutidine at the composition for\nwhich the system undergoes a critical demixing transition on warming. Colloidal\nsilica, with appropriate surface chemistry, is dispersed while the system is in\nthe single-fluid phase; the composite sample is then slowly warmed well beyond\nthe critical temperature. The liquids phase separate via spinodal decomposition\nand the particles become swept up on the newly created interfaces. As the\ndomains coarsen the interfacial area decreases and the particles eventually\nbecome jammed together. The resulting structures have a significant yield\nstress and are stable for many months. Here we begin to explore the complex\nwetting properties of fluorescently-tagged silica surfaces in water-lutidine\nmixtures, showing how they can be tuned to allow bijel creation. Additionally\nwe demonstrate how the particle properties change with time while they are\nimmersed in the solvents."
    },
    {
        "anchor": "The wormhole move: A new algorithm for polymer simulations: A new Monte Carlo move for polymer simulations is presented. The ``wormhole''\nmove is build out of reptation steps and allows a polymer to reptate through a\nhole in space; it is able to completely displace a polymer in time N^2 (with N\nthe polymer length) even at high density. This move can be used in a similar\nway to configurational bias, in particular it allows grand canonical moves, it\nis applicable to copolymers and can be extended to branched polymers. The main\nadvantage is speed since it is exponentially faster in N than configurational\nbias, but is also easier to program.",
        "positive": "Intermolecular distance and density scaling of dynamics in molecular\n  liquids: A broad variety of liquids conform to density scaling: relaxation times\nexpressed as a function of the ratio of temperature to density, the latter\nraised to a material constant {\\gamma}. For atomic liquids interacting only\nthrough simple pair potentials, the exponent {\\gamma} is very nearly equal to\nn/3, where n is the steepness of the intermolecular potential, while for\nmolecular liquids having rigid bonds and built using the same interatomic\npotential, {\\gamma}>n/3. We find that for this class of molecular liquids\n{\\gamma}=n/{\\delta}, where the parameter {\\delta} relates the intermolecular\ndistance to the density along an isomorph (line of approximately constant\ndynamics and structure). {\\delta} depends only on the molecular structure and\nnot the interatomic potential."
    },
    {
        "anchor": "A numerical model for the trans-membrane voltage of vesicles: The Immersed Interface Method is employed to solve the time-varying electric\nfield equations around a three-dimensional vesicle. To achieve second-order\naccuracy the implicit jump conditions for the electric potential, up to the\nsecond normal derivative, are derived. The trans-membrane potential is\ndetermined implicitly as part of the algorithm. The method is compared to an\nanalytic solution based on spherical harmonics and verifies the second-order\naccuracy of the underlying discretization even in the presence of solution\ndiscontinuities. A sample result for an elliptic interface is also presented.",
        "positive": "Cubatic phase for tetrapods: We investigate the phase behavior of tetrapods, hard non-convex bodies formed\nby 4 rods connected under tetrahedral angles. We predict that, depending on the\nrelative lengths of the rods these particles can form a uniaxial nematic phase,\nand more surprisingly they can exhibit a cubatic phase, a special case of the\nbiaxial nematic phase. These predictions may be experimentally testable, as\nexperimental realizations of tetrapods have recently become available."
    },
    {
        "anchor": "Dynamical thickening transition in plate coating with concentrated\n  surfactant solutions: We present a large range of experimental data concerning the influence of\nsurfactants on the well-known Landau-Levich-Derjaguin experiment where a liquid\nfilm is generated by pulling a solid plate out of a bath. The thickness h of\nthe film was measured as a function of the pulling velocity V for different\nkind of surfactant and at various concentrations. Measuring the thickening\nfactor $\\alpha=h/h_{LLD}$, where hLLD is obtained for a pure liquid, in a wide\nrange of capillary ($Ca=\\eta V/\\gamma$), two regimes of constant thickening can\nbe identified: at small capillary number, $\\alpha$ is large due to a\nconfinement and surface elasticity (or Marangoni) effects and at large Ca,\n$\\alpha$ is slightly higher than unity, due to surface viscous effects. At\nintermediate Ca, $\\alpha$ decreases as Ca increases along a \"dynamic\ntransition\". In the case of non-ionic surfactants, the dynamic transition\noccurs at a fixed Ca, independently of the surfactant concentration, while for\nionic surfactants, the dynamic transition depends on the concentration due to\nthe existence of an electrostatic barrier. The control of physico-chemical\nparameters allowed us to elucidate the nature of the dynamic transition and to\nrelate it to surface rheology.",
        "positive": "Simulating (electro)hydrodynamic effects in colloidal dispersions:\n  smoothed profile method: Previously, we have proposed a direct simulation scheme for colloidal\ndispersions in a Newtonian solvent [Phys.Rev.E 71,036707 (2005)]. An improved\nformulation called the ``Smoothed Profile (SP) method'' is presented here in\nwhich simultaneous time-marching is used for the host fluid and colloids. The\nSP method is a direct numerical simulation of particulate flows and provides a\ncoupling scheme between the continuum fluid dynamics and rigid-body dynamics\nthrough utilization of a smoothed profile for the colloidal particles.\nMoreover, the improved formulation includes an extension to incorporate\nmulti-component fluids, allowing systems such as charged colloids in\nelectrolyte solutions to be studied. The dynamics of the colloidal dispersions\nare solved with the same computational cost as required for solving\nnon-particulate flows. Numerical results which assess the hydrodynamic\ninteractions of colloidal dispersions are presented to validate the SP method.\nThe SP method is not restricted to particular constitutive models of the host\nfluids and can hence be applied to colloidal dispersions in complex fluids."
    },
    {
        "anchor": "Time scale of entropic segregation of flexible polymers in confinement:\n  Implications for chromosome segregation in filamentous bacteria: We report molecular dynamics simulations of the segregation of two\noverlapping chains in cylindrical confinement. We find that the entropic\nrepulsion between the chains can be sufficiently strong to cause segregation on\na time scale that is short compared to the one for diffusion. This result\nimplies that entropic driving forces are sufficiently strong to cause rapid\nbacterial chromosome segregation.",
        "positive": "The role of advective inertia in active nematic turbulence: Suspensions of active agents with nematic interactions exhibit complex\nspatio-temporal dynamics such as mesoscale turbulence. Since the Reynolds\nnumber of microscopic flows is very small on the scale of individual agents,\ninertial effects are typically excluded in continuum theories of active nematic\nturbulence. Whether active stresses can collectively excite inertial flows is\ncurrently unclear. To address this question, we investigate a two-dimensional\ncontinuum theory for active nematic turbulence. In particular, we compare\nmesoscale turbulence with and without the effects of advective inertia. We find\nthat inertial effects can influence the flow already close to the onset of the\nturbulent state and, moreover, give rise to large-scale fluid motion for strong\nactive driving. A detailed analysis of the kinetic energy budget reveals an\nenergy transfer to large scales mediated by inertial advection. While this\ntransfer is small in comparison to energy injection and dissipation, its\neffects accumulate over time. The inclusion of friction, which is typically\npresent in experiments, can compensate for this effect. The findings suggest\nthat the inclusion of inertia and friction may be necessary for dynamically\nconsistent theories of active nematic turbulence."
    },
    {
        "anchor": "Manipulation and assembly of nanowires with holographic optical traps: We demonstrate that semiconductor nanowires measuring just a few nanometers\nin diameter can be translated, rotated, cut, fused and organized into\nnontrivial structures using holographic optical traps. The holographic approach\nto nano-assembly allows for simultaneous independent manipulation of multiple\nnanowires, including relative translation and relative rotation.",
        "positive": "Hiding in plain view: Colloidal self-assembly from polydisperse\n  populations: We report small-angle x-ray scattering (SAXS) experiments on aqueous\ndispersions of colloidal silica with a broad monomodal size distribution\n(polydispersity 18%, size 8 nm). Over a range of volume fractions the silica\nparticles segregate to build first one, then two distinct sets of colloidal\ncrystals. These dispersions thus demonstrate fractional crystallization and\nmultiple-phase (bcc, Laves AB$_2$, liquid) coexistence. Their remarkable\nability to build complex crystal structures from a polydisperse population\noriginates from the intermediate-range nature of interparticle forces, and\nsuggests routes for designing self-assembling colloidal crystals from the\nbottom-up."
    },
    {
        "anchor": "Dynamics and Rheology of Vesicle Suspensions in Wall-Bounded Shear Flow: The dynamics and rheology of suspensions of fluid vesicles or red blood cells\nis investigated by a combination of molecular dynamics and mesoscale\nhydrodynamics simulations in two dimensions. The vesicle suspension is confined\nbetween two no-slip walls, which are driven externally to generate a shear flow\nwith shear rate $\\dot\\gamma$. The flow behavior is studied as a function of\n$\\dot\\gamma$, the volume fraction of vesicles, and the viscosity contrast\nbetween inside and outside fluids. Results are obtained for the encounter and\ninteractions of two vesicles, the intrinsic viscosity of the suspension, and\nthe cell-free layer near the walls.",
        "positive": "Dynamical heterogeneity in periodically deformed polymer glasses: The dynamics of structural relaxation in a model polymer glass subject to\nspatially-homogeneous, time-periodic shear deformation is investigated using\nmolecular dynamics simulations. We study a coarse-grained bead-spring model of\nshort polymer chains below the glass transition temperature. It is found that\nat small strain amplitudes, the segmental dynamics is nearly reversible over\nabout $10^4$ cycles, while at strain amplitudes above a few percent, polymer\nchains become fully relaxed after a hundred cycles. At the critical strain\namplitude, the transition from slow to fast relaxation dynamics is associated\nwith the largest number of dynamically correlated monomers as indicated by the\npeak value of the dynamical susceptibility. The analysis of individual monomer\ntrajectories showed that mobile monomers tend to assist their neighbors to\nbecome mobile and aggregate into relatively compact transient clusters."
    },
    {
        "anchor": "Electrostatic interaction between colloidal particles trapped at an\n  electrolyte interface: The electrostatic interaction between colloidal particles trapped at the\ninterface between two immiscible electrolyte solutions is studied in the limit\nof small inter-particle distances. Within an appropriate model exact analytic\nexpressions for the electrostatic potential as well as for the surface and line\ninteraction energies are obtained. They demonstrate that the widely used\nsuperposition approximation, which is commonly applied to large distances\nbetween the colloidal particles, fails qualitatively at small distances and is\nquantitatively unreliable even at large distances. Our results contribute to an\nimproved description of the interaction between colloidal particles trapped at\nfluid interfaces.",
        "positive": "Effects of Cooling Rate on Structural Relaxation in Amorphous Drugs:\n  Elastically Collective Nonlinear Langevin Equation Theory and Machine\n  Learning Study: Theoretical approaches are formulated to investigate the molecular mobility\nunder various cooling rates of amorphous drugs. We describe the structural\nrelaxation of a tagged molecule as a coupled process of cage-scale dynamics and\ncollective molecular rearrangement beyond the first coordination shell. The\ncoupling between local and non-local dynamics behaves distinctly in different\nsubstances. Theoretical calculations for the structural relaxation time, glass\ntransition temperature, and dynamic fragility are carried out over twenty-two\namorphous drugs and polymers. Numerical results have a quantitatively good\naccordance with experimental data and the extracted physical quantities using\nthe Vogel-Fulcher-Tammann fit function and machine learning. The machine\nlearning method reveals the linear relation between the glass transition\ntemperature and the melting point, which is a key factor for pharmaceutical\nsolubility. Our predictive approaches are reliable tools for developing drug\nformulation."
    },
    {
        "anchor": "Vibrational spectrum derived from the local mechanical response in\n  disordered solids: The low-frequency vibrations of glasses are markedly different from those of\ncrystals. These vibrations have recently been categorized into two types:\nspatially extended vibrations, whose vibrational density of states (vDOS)\nfollows a non-Debye quadratic law, and quasilocalized vibrations (QLVs), whose\nvDOS follows a quartic law. The former are explained by elasticity theory with\nquenched disorder and microscopic replica theory as being a consequence of\nelastic instability, but the origin of the latter is still debated. Here, we\nshow that the latter can also be directly derived from elasticity theory with\nquenched disorder. We find another elastic instability that the theory\nencompasses but that has been overlooked so far, namely, the instability of the\nsystem against a local dipolar force. This instability gives rise to an\nadditional contribution to the vDOS, and the spatial structure and energetics\nof the mode originating from this instability are consistent with those of the\nQLVs. Finally, we construct a model in which the additional contribution to the\nvDOS follows a quartic law.",
        "positive": "Elasticity-mediated self-organization and colloidal interactions of\n  solid spheres with tangential anchoring in a nematic liquid crystal: Using laser tweezers and fluorescence confocal polarizing microscopy, we\nstudy colloidal interactions of solid microspheres in the nematic bulk caused\nby elastic distortions around the particles with strong tangential surface\nanchoring. The particles aggregate into chains directed at about 30 degrees to\nthe far field director and, at higher concentrations, form complex kinetically\ntrapped structures. We characterize the distance and angular dependencies of\nthe colloidal interaction forces."
    },
    {
        "anchor": "Protein threading by learning: Using techniques borrowed from statistical physics and neural networks, we\ndetermine the parameters, associated with a scoring function, that are chosen\noptimally to ensure complete success in threading tests in a training set of\nproteins. These parameters provide a quantitative measure of the propensities\nof amino acids to be buried or exposed and to be in a given secondary structure\nand are a good starting point for solving both the threading and design\nproblems.",
        "positive": "Phase diagrams of charged colloidal rods: can a uniaxial charge\n  distribution break chiral symmetry?: We construct phase diagrams for charged rodlike colloids within the\nsecond-virial approximation as a function of rod concentration, salt\nconcentration, and colloidal charge. Besides the expected isotropic-nematic\ntransition, we also find parameter regimes with a coexistence between a nematic\nand a second, more highly aligned nematic phase including an\nisotropic-nematic-nematic triple point and a nematic-nematic critical point,\nwhich can all be explained in terms of the twisting effect. We compute the\nFrank elastic constants to see if the twist elastic constant can become\nnegative, which would indicate the possibility of a cholesteric phase\nspontaneously forming. Although the twisting effect reduces the twist elastic\nconstant, we find that it always remains positive. In addition, we find that\nfor finite aspect-ratio rods the twist elastic constant is also always\npositive, such that there is no evidence of chiral symmetry breaking due to a\nuniaxial charge distribution."
    },
    {
        "anchor": "Active Brownian particles in external force fields: field-theoretical\n  models, generalized barometric law, and programmable density patterns: We investigate the influence of external forces on the collective dynamics of\ninteracting active Brownian particles in two as well as three spatial\ndimensions. Via explicit coarse graining, we derive predictive models that are\napplicable for space- and time-dependent external force fields. We study these\nmodels for the cases of gravity and harmonic traps. In particular, we derive a\ngeneralized barometric formula for interacting active Brownian particles under\ngravity that is valid for low to high concentrations and activities of the\nparticles. Furthermore, we show that one can use an external harmonic trap to\ninduce motility-induced phase separation in systems that, without external\nfields, remain in a homogeneous state. This finding makes it possible to\nrealize programmable density patterns in systems of active Brownian particles.\nOur analytic predictions are found to be in very good agreement with Brownian\ndynamics simulations.",
        "positive": "Kinetics of phase transition from lamellar to hexagonally packed\n  cylinders for a triblock copolymer in a selective solvent: We examined the kinetics of the transformation from the lamellar (LAM) to the\nhexagonally packed cylinder (HEX) phase for the triblock copolymer,\npolystyrene-b-poly (ethylene-co-butylene)-b-polystyrene (SEBS) in dibutyl\nphthalate (DBP), a selective solvent for polystyrene (PS), using time-resolved\nsmall angle x-ray scattering (SAXS). We observe the HEX phase with the EB block\nin the cores at a lower temperature than the LAM phase due to the solvent\nselectivity of DBP for the PS block. Analysis of the SAXS data for a deep\ntemperature quench well below the LAM-HEX transition shows that the\ntransformation occurs in a one-step process. We calculate the scattering using\na geometric model of rippled layers with adjacent layers totally out of phase\nduring the transformation. The agreement of the calculations with the data\nfurther supports the continuous transformation mechanism from the LAM to HEX\nfor a deep quench. In contrast, for a shallow quench close to the OOT we find\nagreement with a two-step nucleation and growth mechanism."
    },
    {
        "anchor": "The nonlinear motion of cells subject to external forces: To develop a minimal model for a cell moving in a crowded environment such as\nin tissue, we investigate the response of a liquid drop of active matter moving\non a flat rigid substrate to forces applied at its boundaries. We consider two\ndifferent self-propulsion mechanisms, active stresses and treadmilling\npolymerisation, and we investigate how the active drop motion is altered by\nthese surface forces. We find a highly non-linear response to forces that we\ncharacterise using drop velocity, drop shape, and the traction between the drop\nand the substrate. Each self-propulsion mechanism gives rise to two main modes\nof motion: a long thin drop with zero traction in the bulk, mostly occurring\nunder strong stretching forces, and a parabolic drop with finite traction in\nthe bulk, mostly occurring under strong squeezing forces. In each case there is\na sharp transition between parabolic, and long thin drops as a function of the\napplied forces and indications of drop break-up where large forces stretch the\ndrop.",
        "positive": "On spectroscopic structure of two interacting electrons in a quantum dot: The shifted 1/N expansion technique, used by El-Said (Phys. Rev. B 61, 13026\n(2000)), to study the relative Hamiltonian of two interacting electrons\nconfined in a quantum dot, is investigated. El-Said's results from SLNT are\nrevised and results from an alternative method are also reported. The\ndistinctive role of the central spike term, $(m^2-1/4)/q^2$, in determinig the\nspectral properties of the above problem is shown, moreover."
    },
    {
        "anchor": "Deposition of general ellipsoidal particles: We present a systematic overview of granular deposits composed of ellipsoidal\nparticles with different particle shapes and size polydispersities. We study\nthe density and anisotropy of such deposits as functions of size polydispersity\nand two shape parameters that fully describe the shape of a general ellipsoid.\nOur results show that, while shape influences significantly the macroscopic\nproperties of the deposits, polydispersity plays apparently a secondary role.\nThe density attains a maximum for a particular family of non-symmetrical\nellipsoids, larger than the density observed for prolate or oblate ellipsoids.\nAs for anisotropy measures, the contact forces show are increasingly preferred\nalong the vertical direction as the shape of the particles deviates for a\nsphere. The deposits are constructed by means of an efficient molecular\ndynamics method, where the contact forces are efficiently and accurately\ncomputed. The main results are discussed in the light of applications for\nporous media models and sedimentation processes.",
        "positive": "The JETSPIN User Manual (Version 1.20): JETSPIN is an open-source computer program specifically designed to simulate\nthe electrospinning process of nanofibers. This manual provides an overview of\nJETSPIN, focusing primarily on its structure, parallel implementations,\nfunctionality, performance, and availability. The code is designed to exploit\ndifferent computational architectures, from single to parallel processor\nworkstations."
    },
    {
        "anchor": "The effect of soft repulsive interactions on the diffusion of particles\n  in quasi-one-dimensional channels: A hopping time approach: Fluids confined to quasi-one-dimensional channels exhibit a dynamic crossover\nfrom single file diffusion to normal diffusion as the channel becomes wide\nenough for particles to hop past each other. In the crossover regime, where\nhopping events are rare, the diffusion coefficient in the long time limit can\nbe related to a hopping time that measures the average time it takes a particle\nto escape the local cage formed by its neighbours. In this work, we show that a\ntransition state theory that calculates the free energy barrier for two\nparticles attempting to pass each other in the small system isobaric ensemble\nis able to quantitatively predict the hopping time in a system of\ntwo-dimensional soft repulsive discs [$U(r_{ij})=(\\sigma/r_{ij})^{\\alpha}$]\nconfined to a hard walled channel over a range of channel radii and degrees of\nparticle softness measured in terms of $1/\\alpha$. The free energy barrier\nexhibits a maximum at intermediate values of $\\alpha$ that moves to smaller\nvalues of $1/\\alpha$ (harder particles) as the channel becomes narrower.\nHowever, the presence of the maximum is only observed in the hopping times for\nwide channels because the interaction potential dependence of the kinetic\nprefactor plays an increasingly important role for narrower channels. We also\nbegin to explore how our transition state theory approach can be used to\noptimize and control dynamics in confined quasi-one-dimensional fluids.",
        "positive": "Beware of CaBER: filament thinning rheometry doesn't give `the'\n  relaxation time of polymer solutions: The viscoelastic relaxation time {\\tau} of a polymer solution is often\nmeasured using Capillary Breakup Extensional Rheometry (CaBER) where a droplet\nis placed between two plates which are pulled apart to form a thinning\nfilament. For a slow plate retraction protocol, required to avoid\ninertio-capillary oscillations for low-viscosity liquids, we show\nexperimentally that the CaBER relaxation time inferred from the exponential\nthinning regime is in fact an apparent relaxation time that increases\nsignificantly when increasing the plate diameter and the droplet volume.\nSimilar results are obtained with a Dripping-onto-Substrate (DoS) method. This\ndependence on the flow history before the formation of the viscoelastic\nfilament is in contradiction with polymer models such as Oldroyd-B that predict\na filament thinning rate 1/3{\\tau} which is a material property independent of\ngeometrical factors. We show that this is not due to artefacts such as solvent\nevaporation or polymer degradation and that it cannot be universally explained\nby the finite extensibility of polymer chains."
    },
    {
        "anchor": "Renormalization of the one-loop theory of fluctuations in polymer blends\n  and diblock copolymer melts: Attempts to use coarse-grained molecular theories to calculate corrections to\nthe random-phase approximation (RPA) for correlations in polymer mixtures have\nbeen plagued by an unwanted sensitivity to the value of an arbitrary cutoff\nlength, {\\it i.e.}, by an ultraviolet (UV) divergence. We analyze the UV\ndivergence of the inverse structure factor $S^{-1}(k)$ predicted by a\n`one-loop' approximation similar to that used in several previous studies. We\nconsider both miscible homopolymer blends and disordered diblock copolymer\nmelts. We show, in both cases, that all UV divergent contributions can be\nabsorbed into a renormalization of the values of the phenomenological\nparameters of a generalized self-consistent field theory (SCFT). This\nobservation allows the construction of a UV convergent theory of corrections to\nSCFT phenomenology. The UV-divergent one-loop contribution to $S^{-1}(k)$ are\nshown to be the sum of: (i) a $k$-independent contribution that arises from a\nrenormalization of the effective $\\chi$ parameter, (ii) a $k$-dependent\ncontribution that arises from a renormalization of monomer statistical segment\nlengths, (iii) a contribution proportional to $k^{2}$ that arises from a\nsquare-gradient contribution to the one-loop fluctuation free energy, and (iv)\na $k$-dependent contribution that is inversely proportional to the degree of\npolymerization, which arises from local perturbations in fluid structure near\nchain ends and near junctions between blocks in block copolymers.",
        "positive": "Phenomenological Theory of Isotropic-Genesis Nematic Elastomers: We consider the impact of the elastomer network on the structure and\nfluctuations in the isotropic-genesis nematic elastomer, via a phenomenological\nmodel that underscores the role of network compliance. The model contains a\nnetwork-mediated nonlocal interaction as well as a new kind of random field,\nwhich reflects the memory of the nematic order present at cross-linking, and\nalso encodes local anisotropy due to localized polymers. Thus, we predict a\nregime of short-ranged oscillatory spatial correlations (both thermal and\nglassy) in the nematic alignment trapped into the network."
    },
    {
        "anchor": "Effect of concentration on the thermodynamics of sodium chloride aqueous\n  solutions in the supercooled regime: Molecular Dynamics simulations are performed on two sodium chloride solutions\nin TIP4P water with concentrations c=1.36 mol/kg and c=2.10 mol/kg upon\nsupercooling. The isotherms and isochoresplanes are calculated. The temperature\nof maximum density line and the limit of mechanical stability line are obtained\nfrom the analysis of the thermodynamic planes. The comparison of the results\nshows that for densities well above the limit of mechanical stability, the\nisotherms and isochores of the sodium chloride aqueous solution shift to lower\npressures upon increasing concentration while the limit of mechanical stability\nis very similar to that of bulk waterfor both concentrations. We also find that\nthe temperature of maximum density line shifts to lower pressures and\ntemperatures upon increasing concentration. Indications of the presence ofa\nliquid-liquid coexistence are found for both concentrations.",
        "positive": "Quantum-well states in ultrathin Ag(111) films deposited onto\n  H-passivated Si(111)-(1x1) surfaces: Ag(111) films were deposited at room temperature onto H-passivated\nSi(111)-(1x1) substrates, and subsequently annealed at 300 C. An abrupt\nnon-reactive Ag/Si interface is formed, and very uniform non-strained Ag(111)\nfilms of 6-12 monolayers have been grown. Angle resolved photoemission\nspectroscopy has been used to study the valence band electronic properties of\nthese films. Well-defined Ag sp quantum-well states (QWS) have been observed at\ndiscrete energies between 0.5-2eV below the Fermi level, and their dispersions\nhave been measured along the GammaK, GammaMM'and GammaL symmetry directions.\nQWS show a parabolic bidimensional dispersion, with in-plane effective mass of\n0.38-0.50mo, along the GammaK and GammaMM' directions, whereas no dispersion\nhas been found along the GammaL direction, indicating the low-dimensional\nelectronic character of these states. The binding energy dependence of the QWS\nas a function of Ag film thickness has been analyzed in the framework of the\nphase accumulation model. According to this model, a reflectivity of 70% has\nbeen estimated for the Ag-sp states at the Ag/H/Si(111)-(1x1) interface."
    },
    {
        "anchor": "Magneto-mechanical Coupling in Thermal Amorphous Solids: Standard approaches to magneto-mechanical interactions in thermal magnetic\ncrystalline solids involve Landau functionals in which the lattice anisotropy\nand the resulting magnetization easy axes are taken explicitly into account. In\nglassy systems one needs to develop a theory in which the amorphous structure\nprecludes the existence of an easy axis, and in which the constituent particles\nare free to respond to their local amorphous surroundings and the resulting\nforces. We present a theory of all the mixed responses of an amorphous solids\nto mechanical strains and magnetic fields. Atomistic models are proposed in\nwhich we test the predictions of magnetostriction for both bulk and nano-film\namorphous samples. The application to nano-films with emergent self-affine free\ninterfaces requires a careful definition of the film 'width' and its change due\nto the magnetostriction effect.",
        "positive": "Dipolar oscillations in a quantum degenerate Fermi-Bose atomic mixture: We study the dynamics of coupled dipolar oscillations in a Fermi-Bose mixture\nof $^{40}$K and $^{87}$Rb atoms. This low-energy collective mode is strongly\naffected by the interspecies interactions. Measurements are performed in the\ndynamical and quantum degenerate regimes and evidence the crucial role of the\nstatistical properties of the mixture. At the onset of quantum degeneracy, we\ninvestigate the role of Pauli blocking and superfluidity for K and Rb atoms,\nrespectively, resulting in a change in the collisional interactions."
    },
    {
        "anchor": "Local Elastic Constants in Thin Films of an FCC Crystal: In this work we present a formalism for the calculation of the local elastic\nconstants in inhomogeneous systems based on a method of planes. Unlike previous\nwork, this formalism does not require the partitioning of the system into a set\nof finite volumes over which average elastic constants are calculated. Results\nfor the calculation of the local elastic constants of a nearest neighbor\nLennard-Jones fcc crystal in the bulk and in a thin film are presented. The\nlocal constants are calculated at exact planes of the (001) face of the\ncrystal. The average elastic constants of the bulk system are also computed and\nare consistent with the local constants. Additionally we present the local\nstress profiles in the thin film when a small uniaxial strain is applied. The\nresulting stress profile compares favorably with the stress profile predicted\nvia the local elastic constants. The surface melting of a model for argon for\nwhich experimental and simulation data are available is also studied within the\nframework of this formalism.",
        "positive": "Orientational orders of small anisotropic molecules confined in slit\n  pores: We have studied phase behavior of hard gaussian overlap molecules with small\nanisotropic parameter confined in two plane parallel structureless hard walls.\nOur investigation based on standard constant-NPT Monte Carlo molecular\nsimulation led us to some interesting findings. For small anisotropic molecules\nthe nematic phase is instable in bulk, while, if the distance between the walls\nis small enough, an orientation-ordered phase can form. This result indicates\nthat the required molecular elongation forming liquid-crystal phases is smaller\nin confinement than that in bulk. Considering the value of the elongation of\nmolecules, the computed result inplies that small molecule liquid crystals may\nexist in confinement."
    },
    {
        "anchor": "Nonuniform heating of a substrate in evaporative lithography: This work is devoted to a method to generate particle cluster assemblies, and\nconnected to evaporative lithography. Experiments are carried out using\nnonuniform evaporation of an isopropanol film containing polystyrene\nmicrospheres in a cylindrical cell. The local inhomogeneity of the vapor flux\ndensity is achieved by exploiting the temperature gradient. A copper rod is\nmounted in the central part of the bottom of the cell for further heating. The\nthermocapillary flow resulting from the surface tension gradient, due in turn\nto the temperature drop, transfers the particles that were originally at rest\nat the bottom of the cell. The effect of the initial thickness of the liquid\nlayer on the height and base area of the cluster formed in the central region\nof the cell is studied. The velocity is measured using particle image\nvelocimetry. A model describing the initial stage of the process is developed.\nThe equations of heat transfer and thermal conductivity are used to define the\ntemperature distribution in the liquid and in the cell. The fluid flow is\nsimulated using the lubrication approximation. The particle distribution is\nmodeled using the convection-diffusion equation. The evaporation flux density\nis calculated using the Hertz-Knudsen equation. The dependence of the liquid\nviscosity on the particle concentration is described by Mooney's formula.\nNumerical results show that the liquid film gradually becomes thinner in the\ncentral region, as the surface tension decreases with the increasing\ntemperature. The liquid flow is directed to the heater near the substrate, and\nit transfers the particles to the center of the cell. The volume fraction of\nthe particles increases over time in this region. The heat flow from the heater\naffects the geometry of the cluster for two reasons: first, the Marangoni flow\nvelocity depends on the temperature gradient, and second, the decrease ...",
        "positive": "Influence of non-conservative optical forces on the dynamics of\n  optically trapped colloidal spheres: The fountain of probability: We demonstrate both experimentally and theoretically that a colloidal sphere\ntrapped in a static optical tweezer does not come to equilibrium, but rather\nreaches a steady state in which its probability flux traces out a toroidal\nvortex. This non-equilibrium behavior can be ascribed to a subtle bias of\nthermal fluctuations by non-conservative optical forces. The circulating sphere\ntherefore acts as a Brownian motor. We briefly discuss ramifications of this\neffect for studies in which optical tweezers have been treated as potential\nenergy wells."
    },
    {
        "anchor": "A link between anomalous viscous loss and boson peak in soft jammed\n  solids: Soft jammed solids exhibit intriguing mechanical properties, while their\nlinear response is elusive. In particular, foams and emulsions generally reveal\nanomalous viscous loss with the loss and storage modulus following $G^{\\prime\n\\prime} \\propto \\sqrt{\\omega}$ and $G^{\\prime} \\propto \\omega^0$. In this\nstudy, we offer a comprehensive microscopic understanding of this behavior.\nUsing microrheology experiment, we measured $G^* = G^{\\prime} + i G^{\\prime\n\\prime}$ of concentrated emulsions in a wide range of frequencies. In theory,\nwe applied a linear response formalism for microrheology to a soft sphere model\nthat undergoes the jamming transition. We find that the theory quantitatively\nexplains the experiments without the need for parameter adjustments. Our\nanalysis reveals that the anomalous viscous loss results from the boson peak,\nwhich is a universal vibrational property of amorphous solids and reflects the\nmarginal stability in soft jammed solids. We discuss that the anomalous viscous\nloss is universal in systems with various interparticle interactions as it\nstems from the universal boson peak, and it even survives below the jamming\ndensity where thermal fluctuation is pronounced and the dynamics becomes\ninherently nonlinear.",
        "positive": "Supercritical Gr\u00fcneisen parameter and its universality at the Frenkel\n  line: We study thermo-mechanical properties of matter at extreme conditions deep in\nthe supercritical state, at temperatures exceeding the critical one up to four\norders of magnitude. We calculate the Gr\\\"{u}neisen parameter {\\gamma} and find\nthat it decreases with temperature from 3 to 1 on isochores depending on the\ndensity. Our results indicate that from the perspective of thermo-mechanical\nproperties, the supercritical state is characterized by the wide range of\n{\\gamma} which includes the solid-like values - an interesting finding in view\nof the common perception of the supercritical state as being an intermediate\nstate between gases and liquids. We rationalize this result by considering the\nrelative weights of oscillatory and diffusive components of the supercritical\nsystem below the Frenkel line. We also find that {\\gamma} is nearly constant at\nthe Frenkel line above the critical point and explain this universality in\nterms of pressure and temperature scaling of system properties along the lines\nwhere particle dynamics changes qualitatively."
    },
    {
        "anchor": "DNA Elasticity : Topology of Self-Avoidance: We present a theoretical treatment of DNA stretching and twisting\nexperiments, in which we discuss global topological subtleties of self avoiding\nribbons and provide an underlying justification for the worm like rod chain\n(WLRC) model proposed by Bouchiat and Mezard. Some theoretical points regarding\nthe WLRC model are clarified: the writhe of open curves and the use of an\nadjustable cutoff parameter to ``regularise'' the model. Our treatment brings\nout the precise relation between the worm like chain (WLC), the paraxial worm\nlike chain (PWLC) and the WLRC models. We describe the phenomenon of\n``topological untwisting'' and the resulting collapse of link sectors in the\nWLC model and note that this leads to a free energy profile {\\it{periodic}} in\nthe applied link. This periodicity disappears when one takes into account the\ntopology of self avoidance or at large stretch forces (paraxial limit). We note\nthat the difficult nonlocal notion of self avoidance can be replaced (in an\napproximation) by the simpler local notion of ``south avoidance'' in the WLRC\nmodel. This gives an explanation for the efficacy of the approach of Bouchiat\nand Mezard in explaining the `hat curves' using the WLRC model.\n  We propose a new class of experiments to probe the continuous transition\nbetween the periodic and aperiodic behavior of the free energy.",
        "positive": "Divergence of the Long Wavelength Collective Diffusion Coefficient in\n  Quasi-one and Quasi-two Dimensional Colloid Suspensions: We report the results of experimental studies of the short time-long\nwavelength behavior of collective particle displacements in\nquasi-one-dimensional and quasi-two-dimensional colloid suspensions. Our\nresults are represented by the behavior of the hydrodynamic function H(q) that\nrelates the effective collective diffusion coefficient, D_e(q) with the static\nstructure factor S(q) and the self-diffusion coefficient of isolated particles\nD_0: H(q)=D_e(q)S(q)/D_0. We find an apparent divergence of H(q) as q->0 with\nthe form H(q) proportional to q^-gamma, 1.7<gamma<1.9, for both q1D and q2D\ncolloid suspensions. Given that S(q) does not diverge as q=>0 we infer that\nD_e(q) does. We provide evidence that this divergence arises from the interplay\nof boundary conditions on the flow of the carrier liquid and many-body\nhydrodynamic interactions between colloid particles that affect the long\nwavelength behavior of the particle collective diffusion coefficient in the\nsuspension. We speculate that in the q1D and q2D systems studied the divergence\nof H(q) might be associated with a q-dependent partial slip boundary condition,\nspecifically an effective slip length that increases with decreasing q. We also\nverify, using data from the work of Lin, Rice and Weitz (J. Chem. Phys. 99,\n9585 (1993)), the prediction by Bleibel et al (arXiv:1305.3715), that D_e(q)\nfor a monolayer of colloid particles constrained to lie in the interface\nbetween two fluids diverges as 1/q as q->0. The verification of that\nprediction, which is based on an analysis that allows two-dimensional colloid\nmotion embedded in three-dimensional suspending fluid motion, supports the\ncontention that the boundary conditions that define a q2D system play a very\nimportant role in determining the long wavelength behavior of the collective\ndiffusion coefficient."
    },
    {
        "anchor": "Surface phase transitions in foams and emulsions: Surface phase transitions in surfactant adsorption layers are known to affect\nthe dynamic properties of foams and to induce surface nucleation in freezing\nemulsion drops. Recently, these transitions were found to play a role in\nseveral other phenomena, opening new opportunities for controlling foam and\nemulsion properties. This review presents a brief outlook of the emerging\nopportunities in this area. Three topics are emphasized: (1) The use of\nsurfactant mixtures for inducing phase transitions on bubble surfaces in foams;\n(2) The peculiar properties of natural surfactants saponins which form\nextremely viscoelastic surface layers; and (3) The main phenomena in emulsions,\nfor which the surface phase transitions are important. The overall conclusion\nfrom the reviewed literature is that surface phase transitions could be used as\na powerful tool to control many foam and emulsion properties, but we need\ndeeper understanding of the underlying phenomena to explore fully these\nopportunities.",
        "positive": "Randomly forced DNA: We study the effect of random forces on a double stranded DNA in unzipping\nthe two strands, analogous to the problem of an adsorbed polymer under a random\nforce. The ground state develops bubbles of various lengths as the random force\nfluctuation is increased. The unzipping phase diagram is shown to be\ndrastically different from the pure case."
    },
    {
        "anchor": "Observation and Characterization of the Vestige of the Jamming\n  Transition in a Thermal 3D System: We study the dependence of the pair-correlation function, $g(r)$, and\nparticle mobility on packing fraction in a dense three-dimensional packing of\nsoft colloids made of poly N-isopropyl acrylamide (pNIPAM), a thermo-sensitive\ngel. We find that $g(r)$ for our samples is qualitatively like that of a liquid\nat all packing fractions. There is a peak in $g_{1}$, the height of the first\npeak of $g(r)$, as a function of packing fraction. This peak is identified as\nthe thermal remnant of the T=0 divergence found at the jamming transition in\nsimulations of soft frictionless spheres at zero-temperature. Near where there\nis a peak in $g_{1}$ the particles become arrested on the time scale of the\nexperiment.",
        "positive": "Superfluid Fermi-Fermi mixture: phase diagram, stability, and soliton\n  formation: We study the phase diagram for a dilute Bardeen-Cooper-Schrieffer superfluid\nFermi-Fermi mixture (of distinct mass) at zero temperature using energy\ndensities for the superfluid fermions in one (1D), two (2D), and three (3D)\ndimensions. We also derive the dynamical time-dependent nonlinear\nEuler-Lagrange equation satisfied by the mixture in one dimension using this\nenergy density. We obtain the linear stability conditions for the mixture in\nterms of fermion densities of the components and the interspecies Fermi-Fermi\ninteraction. In equilibrium there are two possibilities. The first is that of a\nuniform mixture of the two components, the second is that of two pure phases of\ntwo components without any overlap between them. In addition, a mixed and a\npure phase, impossible in 1D and 2D, can be created in 3D. We also obtain the\nconditions under which the uniform mixture is stable from an energetic\nconsideration. The same conditions are obtained from a modulational instability\nanalysis of the dynamical equations in 1D. Finally, the 1D dynamical equations\nfor the system are solved numerically and by variational approximation (VA) to\nstudy the bright solitons of the system for attractive interspecies Fermi-Fermi\ninteraction in 1D. The VA is found to yield good agreement to the numerical\nresult for the density profile and chemical potential of the bright solitons.\nThe bright solitons are demonstrated to be dynamically stable. The experimental\nrealization of these Fermi-Fermi bright solitons seems possible with present\nsetups."
    },
    {
        "anchor": "On the incremental equations in surface elasticity: We derive the incremental equations for a hyperelastic solid that incorporate\nsurface tension effect by assuming that the surface energy is a general\nfunction of the surface deformation gradient. The incremental equations take\nthe same simple form as their purely mechanical counterparts and are valid for\nany geometry. In particular, for isotropic materials, the extra surface elastic\nmoduli are expressed in terms of the surface energy function and the two\nsurface principal stretches. The effectiveness of the resulting incremental\ntheory is illustrated by applying it to study the Plateau--Rayleigh and Wilkes\ninstabilities in a solid cylinder.",
        "positive": "Dynamics of short polymer chains in solution: We present numerical and analytical results describing the effect of\nhydrodynamic interactions on the dynamics of a short polymer chain in solution.\nA molecular dynamics algorithm for the polymer is coupled to a direct\nsimulation Monte Carlo algorithm for the solvent. We give an explicit\nexpression for the velocity autocorrelation function of the centre of mass of\nthe polymer which agrees well with numerical results if Brownian dynamics,\nhydrodynamic correlations and sound wave scattering are included."
    },
    {
        "anchor": "Laboratory experiment and discrete-element-method simulation of\n  granular-heap flows under vertical vibration: Granular flow dynamics on a vertically vibrated pile is studied by means of\nboth laboratory experiments and numerical simulations. As already revealed, the\ndepth-averaged velocity of a fully-fluidized granular pile under strong\nvibration, which is measured by a high-speed laser profiler in the experiment,\ncan be explained by the nonlinear diffusion transport model proposed by our\nprevious paper (Tsuji et al, Phys. Rev. Lett. 120, 128001 (2018)). In this\npaper, we report that a similar transport model can be applied to the relation\nbetween the surface velocity and slope in the experiment. These facts are also\nreproduced by particle-scale numerical simulations based on the discrete\nelement method. In addition, using these numerical results, the velocity\nprofile inside the fluidized pile is measured. As a result, we show that the\nflow velocity decreases exponentially with depth from the surface of the pile,\nwhich means that a clearly fluidized region, also known as shear band\nstructure, is localized around the surface. However, its thickness grows\nproportionally with the local height of the pile, i.e., the shear band does not\nconsist of a fluidized layer with a constant thickness. From these features, we\nfinally demonstrate that the integration of this exponentially-decreasing\nvelocity profile is consistent with the depth-averaged velocity predicted by\nthe nonlinear diffusion transport model.",
        "positive": "Viewing Earth's surface as a soft matter landscape: The Earth's surface is composed of a staggering diversity of\nparticulate-fluid mixtures: dry to wet, dilute to dense, colloidal to granular,\nand attractive to repulsive particles. This material variety is matched by the\nrange of relevant stresses and strain rates, from laminar to turbulent flows,\nand steady to intermittent forcing, leading to anything from rapid and\ncatastrophic landslides to the slow relaxation of soil and rocks over geologic\ntimescales. Geophysical flows sculpt landscapes, but also threaten human lives\nand infrastructure. From a physics point of view, virtually all Earth and\nplanetary landscapes are composed of soft matter, in the sense they are both\ndeformable and sensitive to collective effects. Geophysical materials, however,\noften involve compositions and flow geometries that have not yet been examined\nin physics. In this review we explore how a soft-matter perspective has helped\nto illuminate, and even predict, the rich dynamics of Earth materials and their\nassociated landscapes. We also highlight some novel phenomena of geophysical\nflows that challenge, and will hopefully inspire, more fundamental work in soft\nmatter."
    },
    {
        "anchor": "Lift and drag forces on an inclined plow moving over a granular surface: We studied the drag and lift forces acting on an inclined plate while it is\ndragged on the surface of a granular media, both in experiment and numerical\nsimulation. In particular, we investigated the influence of the horizontal\nvelocity of the plate and its angle of attack. We show that a steady wedge of\ngrains is moved in front of the plow and that the lift and drag forces are\nproportional to the weight of this wedge. These constants of proportionality\nvary with the angle of attack but not (or only weakly) on the velocity. We\nfound a universal effective friction law which accounts for the dependence on\nall the above-mentioned parameters. The stress and velocity fields are\ncalculated from the numerical simulations and show the existence of a shear\nband under the wedge and that the pressure is non-hydrostatic. The strongest\ngradients in stress and shear occur at the base of the plow where the\ndissipation rate is therefore highest.",
        "positive": "Seismicity in sheared granular matter: We report on experiments investigating the dynamics of a slider that is\npulled by a spring across a granular medium consisting of a vertical layer of\nphoto-elastic disks. The motion proceeds through a sequence of discrete events,\nanalogous to seismic shocks, in which elastic energy stored in the spring is\nrapidly released. We measure the statistics of several properties of the\nindividual events: the energy loss in the spring, the duration of the movement,\nand the temporal profile of the slider motion. We also study certain\nconditional probabilities and the statistics of mainshock-aftershock sequences.\nAt low driving rates, we observe crackling with Omori-Utsu, Bath, and waiting\ntime laws similar to those observed in seismic dynamics. At higher driving\nrates, where the sequence of events shows strong periodicity, we observe\nscaling laws and asymmetrical event shapes that are clearly distinguishable\nfrom those in the crackling regime."
    },
    {
        "anchor": "Structure of the cholesteric-isotropic interface: The interface of a cholesteric liquid crystal with an isotropic fluid can\ndisplay a range of unusual properties, such as a layer of topological defects\nclose to an undulated interface. These properties have been know for a long\ntime and have been explored for technological applications as a tunable\nsubstrate for colloidal self-assembly. However, from a fundamental point of\nview, this interface remains poorly understood and even basic properties, such\nas the dependence of the surface tension on the attributes of the liquid\ncrystal, remain unknown. Here, we present a systematic calculation of the\nstructure and surface tension of the cholesteric-isotropic interface and how\nthese vary with the properties of the liquid crystal. We also suggest the\nintriguing possibility of wetting of this interface by a blue phase.",
        "positive": "Coexistence of solid and liquid phases in shear jammed colloidal drops: Complex fluids exhibit a variety of exotic flow behaviours under high\nstresses, such as shear thickening and shear jamming. Rheology is a powerful\ntool to characterise these flow behaviours over the bulk of the fluid. However,\nthis technique is limited in its ability to probe fluid behaviour in a\nspatially resolved way. Here, we utilise high-speed imaging and the\nfree-surface geometry in drop impact to study the flow of colloidal\nsuspensions. We report, for the first time, observations of coexisting solid\nand liquid phases due to shear jamming caused by impact. In addition to\nobserving Newtonian-like spreading and bulk shear jamming, we observe the\ntransition between these regimes in the form of localised patches of jammed\nsuspension in the spreading drop. We capture shear jamming as it occurs via a\nsolidification front traveling from the impact point, and show that the speed\nof this front is set by how far the impact conditions are beyond the shear\nthickening transition."
    },
    {
        "anchor": "Polymer chain scission at constant tension - an example of force-induced\n  collective behaviour: The breakage of a polymer chain of segments, coupled by anharmonic bonds with\napplied constant external tensile force is studied by means of Molecular\nDynamics simulation. We show that the mean life time of the chain becomes\nprogressively independent of the number of bonds as the pulling force grows.\nThe latter affects also the rupture rates of individual bonds along the polymer\nbackbone manifesting the essential role of inertial effects in the\nfragmentation process. The role of local defects, temperature and friction in\nthe scission kinetics is also examined.",
        "positive": "Effects of Sequence Disorder on DNA Looping and Cyclization: Effects of sequence disorder on looping and cyclization of the\ndouble-stranded DNA are studied theoretically. Both random intrinsic curvature\nand inhomogeneous bending rigidity are found to result in a remarkably wide\ndistribution of cyclization probabilities. For short DNA segments, the range of\nthe distribution reaches several orders of magnitude for even completely random\nsequences. The ensemble averaged values of the cyclization probability are also\ncalculated, and the connection to the recent experiments is discussed."
    },
    {
        "anchor": "Light-Induced Manipulation of Passive and Active Microparticles: We consider sedimented at a solid wall particles that are immersed in water\ncontaining small additives of photosensitive ionic surfactants. It is shown\nthat illumination with an appropriate wavelength, a beam intensity profile,\nshape and size could lead to a variety of dynamic, both unsteady and\nsteady-state, configurations of particles. These dynamic, well-controlled and\nswitchable particle patterns at the wall are due to an emerging\ndiffusio-osmotic flow that takes its origin in the adjacent to the wall\nelectrostatic diffuse layer, where the concentration gradients of surfactant\nare induced by light. The conventional nonporous particles are passive and can\nmove only with already generated flow. However, porous colloids actively\nparticipate themselves in the flow generation mechanism at the wall, which also\nsets their interactions that can be very long ranged. This light-induced\ndiffusio-osmosis opens novel avenues to manipulate colloidal particles and\nassemble them to various patterns. We show in particular how to create and\nsplit optically the confined regions of particles of tunable size and shape,\nwhere well controlled flow-induced forces on the colloids could result in their\ncristalline packing, formation of dilute lattices of well-separated particles,\nand other states.",
        "positive": "Brownian motion of charged particles driven by correlated noise: Stochastic motion of charged particles in the magnetic field was first\nstudied almost half a century ago in the classical works by Taylor and\nKursunoglu in connection with the diffusion of electrons and ions in plasma. In\ntheir works the long-time limits of the mean square displacement (MSD) of the\nparticles have been found. Later Furuse on the basis of standard Langevin\ntheory generalized their results for arbitrary times. The currently observed\nrevival of these problems is mainly related to memory effects in the diffusion\nof particles, which appear when colored random forces act on the particles from\ntheir surroundings. In the present work an exact analytical solution of the\ngeneralized Langevin equation has been found for the motion of the particle in\nan external magnetic field when the random force is exponentially correlated in\nthe time. The obtained MSD of the particle motion across the field contains a\nterm proportional to the time, a constant term, and contributions exponentially\ndecaying in the time. The results are more general than the previous results\nfrom the literature and are obtained in a considerably simpler way applicable\nto many other problems of the Brownian motion with memory."
    },
    {
        "anchor": "The contact percolation transition: Typical quasistatic compression algorithms for generating jammed packings of\nathermal, purely repulsive particles begin with dilute configurations and then\napply successive compressions with relaxation of the elastic energy allowed\nbetween each compression step. It is well-known that during isotropic\ncompression athermal systems with purely repulsive interactions undergo a\njamming transition at packing fraction $\\phi_J$ from an unjammed state with\nzero pressure to a jammed, rigid state with nonzero pressure. Using extensive\ncomputer simulations, we show that a novel second-order-like transition, the\ncontact percolation transition, which signals the formation of a\nsystem-spanning cluster of mutually contacting particles, occurs at $\\phi_P <\n\\phi_J$, preceding the jamming transition. By measuring the number of\nnon-floppy modes of the dynamical matrix, and the displacement field and\ntime-dependent pressure following compression, we find that the contact\npercolation transition also heralds the onset of complex spatiotemporal\nresponse to applied stress. Thus, highly heterogeneous, cooperative, and\nnon-affine particle motion occurs in unjammed systems significantly below the\njamming transition for $\\phi_P < \\phi < \\phi_J$, not only for jammed systems\nwith $\\phi > \\phi_J$.",
        "positive": "The influence of crosslinkers and magnetic particle distribution along\n  the filament backbone on the magnetic properties of supracolloidal linear\n  polymer-like chains: Diverse polymer crosslinking techniques allow the synthesis of linear\npolymer-like structures whose monomers are colloidal particles. In the case\nwhere all or part of these colloidal particles are magnetic, one can control\nthe behaviour of these supracolloidal polymers, known as magnetic filaments\n(MFs), by applied magnetic fields. However, the response of MFs strongly\ndepends on the crosslinking procedure. In the present study, we employ Langevin\ndynamics simulations to investigate the influence of the type of crosslinking\nand the distribution of magnetic particles within MFs on their response to an\nexternal magnetic field. We found that if the rotation of the dipole moment of\nparticles is not coupled to the backbone of the filament, the impact of the\nmagnetic content is strongly decreased."
    },
    {
        "anchor": "The influence of surface roughness on the rheology of immersed and dry\n  frictional spheres: Pressure-imposed rheometry is used to examine the influence of surface\nroughness on the rheology of immersed and dry frictional spheres in the dense\nregime. The quasi-static value of the effective friction coefficient is not\nsignificantly affected by particle roughness while the critical volume fraction\nat jamming decreases with increasing roughness. These values are found to be\nsimilar in immersed and dry conditions. Rescaling the volume fraction by the\nmaximum volume fraction leads to collapses of rheological data on master\ncurves. The asymptotic behaviors are examined close to the jamming transition.",
        "positive": "A Molecular Dynamics Study of The Translation and Rotation of\n  Amphiphilic Janus Nanoparticles at a Vapor-Liquid Surface: We study the effects of heterogeneity on interfacial pinning and hydrodynamic\ndrag using molecular dynamics (MD) simulations of Janus nanospheres at a\nliquid/vapor interface. We construct the free energy landscape for this system,\nboth in the continuum approximation using surfaces tensions and the\nflat-interface approximation and atomistically using MD and thermodynamic\nintegration. The results of the two methods differ in detail due to interfacial\ndistortion and finite width, as well as thermal fluctuations, and only the MD\nlandscape is consistent with simulations of a nanosphere approaching the\ninterface from the liquid or vapor side. When dragged along an interface, these\nJanus particles exhibit a velocity-dependent tilt accompanied by a weak\nvariation in drag force, but never an enhancement of the drag force beyond the\nvalue when fully immersed. This velocity dependence arises when the interface\nis pinned at heterogeneities and prevents the particle from rotating, and\nsimilar behavior is observed for homogeneous but non-spherical particles. The\noccurrence of different particle orientations having different drag\ncoefficients may lead to an apparent violation of the Stokes-Einstein relation."
    },
    {
        "anchor": "Dynamical transition in translational and rotational dynamics of water\n  in the grooves of DNA duplex at low temperature: We have simulated structure and dynamics of water in the grooves of a DNA\nduplex using moleculear dynamics simulations. We find signatures of a dynamical\ntransition in both translational and orientational dynamics of water molecules\nin both the major and the minor grooves of a DNA duplex. The transition occurs\nat a slightly higher temperature ($T_{GL} \\approx $ 255 K) than the temperature\n($T_L\\approx$ 247 K) where the bulk water is conjectured to undergo a dynamical\ntransition. Groove water, however, exhibits markedly different temperature\ndependence of its properties from the bulk. Entropy calculations reveal that\nthe minor groove water is ordered even at room temperature and the transition\nat $T \\approx$ 255 K can be characterized as a {\\em strong-to-strong} dynamical\ntransition. The low temperature water is characterized by pronounced\ntetrahedral order, as manifested in the sharp rise near $109^{\\circ}$ in the\nO-O-O angle distribution. We find that Adams-Gibbs relation between\nconfigurational entropy and translational diffusion holds quite well when the\ntwo quantities are plotted together in a master plot for different region of\naqueous DNA duplex (bulk, major and minor grooves) at different temperatures.\nThe activation energy for the transfer of water molecules between different\nregions of DNA is found to be independent of temperature.",
        "positive": "Bypassing slip velocity: rotational and translational velocities of\n  autophoretic colloids in terms of surface flux: A standard approach to propulsion velocities of autophoretic colloids with\nthin interaction layers uses a reciprocity relation applied to the slip\nvelocity. But the surface flux (chemical, electrical, thermal, etc.), which is\nthe source of the field driving the slip is often more accessible. We show how,\nunder conditions of low Reynolds number and a field obeying the Laplace\nequation in the outer region, the slip velocity can be bypassed in velocity\ncalculations. In a sense, the actual slip velocity and a normal field\nproportional to the flux density are equivalent for this type of calculation.\nUsing known results for surface traction induced by rotating or translating an\ninert particle in a quiescent fluid, we derive simple and explicit integral\nformulas for translational and rotational velocities of arbitrary spheroidal\nand slender-body autophoretic colloids."
    },
    {
        "anchor": "Dissipative Quantum Transport in Macromolecules: An Effective Field\n  Theory Approach: We introduce an atomistic approach to the dissipative quantum dynamics of\ncharged or neutral excitations propagating through macromolecular systems.\nUsing the Feynman-Vernon path integral formalism, we analytically trace out\nfrom the density matrix the atomic coordinates and the heat bath degrees of\nfreedom. This way we obtain an effective field theory which describes the\nreal-time evolution of the quantum excitation and is fully consistent with the\nfluctuation-dissipation relation. The main advantage of the field-theoretic\napproach is that it allows to avoid using the Keldysh contour formulation. This\nsimplification makes it straightforward to derive Feynman diagrams to\nanalytically compute the effects of the interaction of the propagating quantum\nexcitation with the heat bath and with the molecular atomic vibrations. For\nillustration purposes, we apply this formalism to investigate the loss of\nquantum coherence of holes propagating through a poly(3-alkylthiophene) polymer",
        "positive": "Favoured Local Structures in Liquids and Solids: a 3D Lattice Model: We investigate the connection between the geometry of Favoured Local\nStructures (FLS) in liquids and the associated liquid and solid properties. We\nintroduce a lattice spin model - the FLS model on a face-centered cubic lattice\n- where this geometry can be arbitrarily chosen among a discrete set of 115\npossible FLS. We find crystalline groundstates for all choices of a single FLS.\nSampling all possible FLS's, we identify the following trends: i) low symmetry\nFLS's produce larger crystal unit cells but not necessarily higher energy\ngroundstates, ii) chiral FLS's exhibit to peculiarly poor packing properties,\niii) accumulation of FLS's in supercooled liquids is linked to large crystal\nunit cells, and iv) low symmetry FLS's tend to find metastable structures on\ncooling."
    },
    {
        "anchor": "Coupled eigenmodes in a two-component Bose-Einstein condensate: We have studied the elementary excitations in a two-component Bose-Einstein\ncondensate. We concentrate on the breathing modes and find the elementary\nexcitations to possess avoided crossings and regions of coalescing oscillations\nwhere both components of the condensates oscillate with same frequency. For\nlarge repulsive interactions between the condensates, their oscillational modes\ntend to decouple due to decreased overlap. A thorough investigation of the\neigenmodes near the avoided crossings is presented.",
        "positive": "A new peridynamic formulation with shear deformation for elastic solid: We propose a new peridynamic formulation with shear deformation for linear\nelastic solid. The key idea lies in subtracting the rigid body rotation part\nfrom the total deformation. Based on the strain energy equivalence between\nclassic local model and non-local model, the bond force vector is derived. A\nnew damage rule of maximal deviatoric bond strain for elastic brittle fracture\nis proposed in order to account for both the tensile damage and shear damage.\n2D and 3D numerical examples are tested to verify the accuracy of the current\nperidynamics. The new damage rule is applied to simulate the propagation of\nMode I, II and III cracks."
    },
    {
        "anchor": "Effective potentials and electrostatic interactions in self-assembled\n  molecular bilayers II: the case of biological membranes: We propose a very simple but realistic enough model which allows to include a\nlarge number of molecules in molecular dynamics MD simulations of these\nbilayers, but nevertheless taking into account molecular charge distributions,\nflexible amphiphilic molecules and a reliable model of water. All these\nparameters are essential in a nanoscopic scale study of intermolecular and long\nrange electrostatic interactions. This model was previously used by us to\nsimulate a Newton black film and in this paper we extend our investigation to\nbilayers of the biological membrane type. The electrostatic interactions are\ncalculated using Ewald sums and, for the macroscopic long range electrostatic\ninteractions, we use our previously proposed coarsed fit of the (perpendicular\nto the bilayer plane) molecular charge distributions with gaussian\ndistributions. To study an unique biological membrane (not an stack of\nbilayers), we propose a simple effective external potential that takes into\naccount the microscopic pair distribution functions of water and is used to\nsimulate the interaction with the surrounding water. The method of effective\nmacroscopic and external potentials is extremely simple to implement in\nnumerical simulations, and the spatial and temporal charge inhomogeneities are\nthen roughly taken into account. Molecular dynamics simulations of several\nmodels of a single biological membrane, of neutral or charged polar\namphiphilics, with or without water (using the TIP5P intermolecular potential\nfor water) are included.",
        "positive": "Freezing of a two dimensional fluid in to a crystalline phase : Density\n  functional approach: A free-energy functional for a crystal proposed by Singh and Singh (Europhys.\nLett. {\\bf {88}}, 16005 (2009)) and which contains both the symmetry conserved\nand symmetry broken parts of the direct pair correlation function has been used\nto investigate the crystallization of a two-dimensional fluid. The results\nfound for fluids interacting via the inverse power potential $ u(r)= \\epsilon\n({\\sigma}/{r})^{n} $ for n= 3, 6 and 12 are in good agreement with experimental\nand simulation results. The contribution made by the symmetry broken part to\nthe grand thermodynamic potential at the freezing point is found to increase\nwith the softness of the potential. Our results explain why the\nRamakrishnan-Yussouff (Phys. Rev. B {\\bf 19}, 2775 (1979)) free-energy\nfunctional gave good account of freezing transitions of hard-core potentials\nbut failed for potentials that have soft core and/or attractive tail."
    },
    {
        "anchor": "Crowding of Polymer Coils and Demixing in Nanoparticle-Polymer Mixtures: The Asakura-Oosawa-Vrij (AOV) model of colloid-polymer mixtures idealizes\nnonadsorbing polymers as effective spheres that are fixed in size and\nimpenetrable to hard particles. Real polymer coils, however, are intrinsically\npolydisperse in size (radius of gyration) and may be penetrated by smaller\nparticles. Crowding by nanoparticles can affect the size distribution of\npolymer coils, thereby modifying effective depletion interactions and\nthermodynamic stability. To analyse the influence of crowding on polymer\nconformations and demixing phase behaviour, we adapt the AOV model to mixtures\nof nanoparticles and ideal, penetrable polymer coils that can vary in size. We\nperform Gibbs ensemble Monte Carlo simulations, including trial\nnanoparticle-polymer overlaps and variations in radius of gyration. Results are\ncompared with predictions of free-volume theory. Simulation and theory\nconsistently predict that ideal polymers are compressed by nanoparticles and\nthat compressibility and penetrability stabilise nanoparticle-polymer mixtures.",
        "positive": "Comparing dynamic correlation lengths from an approximation to the\n  four-point dynamic susceptibility and from the picosecond vibrational\n  dynamics: Recently a new approach to the determination of dynamic correlation lengths,\n{\\xi}, for supercooled liquids, based on the properties of the slow\n(picosecond) vibrational dynamics, was carried out [L. Hong, V.N. Novikov, and\nA.P. Sokolov, Phys. Rev. E 83, 061508 (2011)]. Although these vibrational\nmeasurements are typically conducted well below the glass transition\ntemperature, Tg, the assumption is that the structure of the liquid is frozen\nat Tg, so that the {\\xi} characterize dynamic heterogeneity in the supercooled\nliquid state. We compare {\\xi} from this method to values calculated using an\napproximation to the four-point dynamic susceptibility. For 26 different\nmaterials we find good correlation between the two measures; moreover, the\npressure dependences are consistent within the large experimental error.\nHowever, {\\xi} from Boson peak measurements above Tg have a different, and\nunrealistic, temperature dependence."
    },
    {
        "anchor": "Pinned-to-sliding transition and structural crossovers for helically\n  confined charges: We explore the non-equilibrium dissipative dynamics of a system of identical\ncharged particles trapped on a closed helix. The particles are subject to an\nexternal force accelerating them along the underlying structure. The effective\ninteractions between the charges induce a coupling of the center-of-mass to the\nrelative motion which in turn gives rise to a pinned-to-sliding transition with\nincreasing magnitude of the external force. In the sliding regime we observe an\nOhmic behaviour signified by a constant mobility. Within the same regime a\nstructural transition of the helical particle chain takes place with increasing\nthe helix radius leading to a global change of the crystalline arrangement. The\nresulting crystal is characterized by the existence of multiple defects whose\nnumber increases with the helix radius.",
        "positive": "Competing ordered structures formed by particles with a regular\n  tetrahedral patch decoration: We study the ordered equilibrium structures of patchy particles where the\npatches are located on the surface of the colloid such that they form a regular\ntetrahedron. Using optimization techniques based on ideas of evolutionary\nalgorithms we identify possible candidate structures. We retain not only the\nenergetically most favourable lattices but also include a few energetically\nless favourable particle arrangements (i.e., local minima on the enthalpy\nlandscape). Using suitably developed Monte Carlo based simulations techniques\nin an NPT ensemble we evaluate the thermodynamic properties of these candidate\nstructures along selected isobars and isotherms and identify thereby the\nrespective ranges of stability. We demonstrate on a quantitative level that the\nequilibrium structures at a given state point result from a delicate compromise\nbetween entropy, energy (i.e., the lattice sum) and packing."
    },
    {
        "anchor": "Recent progress towards chemically-specific coarse-grained simulation\n  models with consistent dynamical properties: Coarse-grained (CG) models can provide computationally efficient and\nconceptually simple characterizations of soft matter systems. While generic\nmodels probe the underlying physics governing an entire family of free-energy\nlandscapes, bottom-up CG models are systematically constructed from a\nhigher-resolution model to retain a high level of chemical specificity. The\nremoval of degrees of freedom from the system modifies the relationship between\nthe relative time scales of distinct dynamical processes through both a loss of\nfriction and a \"smoothing\" of the free-energy landscape. While these effects\ntypically result in faster dynamics, decreasing the computational expense of\nthe model, they also obscure the connection to the true dynamics of the system.\nThe lack of consistent dynamics is a serious limitation for CG models, which\nnot only prevents quantitatively accurate predictions of dynamical observables\nbut can also lead to qualitatively incorrect descriptions of the characteristic\ndynamical processes. With many methods available for optimizing the structural\nand thermodynamic properties of chemically-specific CG models, recent years\nhave seen a stark increase in investigations addressing the accurate\ndescription of dynamical properties generated from CG simulations. In this\nreview, we present an overview of these efforts, ranging from bottom-up\nparametrizations of generalized Langevin equations to refinements of the CG\nforce field based on a Markov state modeling framework. We aim to make\nconnections between seemingly disparate approaches, while laying out some of\nthe major challenges as well as potential directions for future efforts.",
        "positive": "Ultra-sensitive surface absorption spectroscopy using sub-wavelength\n  diameter optical fibers: The guided modes of sub-wavelength diameter air-clad optical fibers exhibit a\npronounced evanescent field. The absorption of particles on the fiber surface\nis therefore readily detected via the fiber transmission. We show that the\nresulting absorption for a given surface coverage can be orders of magnitude\nhigher than for conventional surface spectroscopy. As a demonstration, we\npresent measurements on sub-monolayers of 3,4,9,10-perylene-tetracarboxylic\ndianhydride (PTCDA) molecules at ambient conditions, revealing the\nagglomeration dynamics on a second to minutes timescale."
    },
    {
        "anchor": "Torsion and Bistability of Double-Twist Elastomers: We investigate the elastic properties of anisotropic elastomers with a\ndouble-twist director field, which is a model for collagen fibrils or blue\nphases. We observe a significant Poynting-like effect, coupling torsion (fibril\ntwist) and extension. For freely-rotating boundary conditions, we identify a\nstructural bistability at very small extensional strains which undergoes a\nsaddle-node bifurcation at a critical strain -- at approximately 1% strain for\na parameterization appropriate for collagen fibrils. With clamped boundary\nconditions appropriate for many experimental setups, the bifurcation is not\npresent. We expect significant helical shape effects when fixed torsion does\nnot equal the equilibrium torsion of freely-rotating boundary conditions, due\nto residual torques.",
        "positive": "Ground-state Properties of Small-Size Nonlinear Dynamical Lattices: We investigate the ground state of a system of interacting particles in small\nnonlinear lattices with M > 2 sites, using as a prototypical example the\ndiscrete nonlinear Schroedinger equation that has been recently used\nextensively in the contexts of nonlinear optics of waveguide arrays, and\nBose-Einstein condensates in optical lattices. We find that, in the presence of\nattractive interactions, the dynamical scenario relevant to the ground state\nand the lowest-energy modes of such few-site nonlinear lattices reveals a\nvariety of nontrivial features that are absent in the large/infinite lattice\nlimits: the single-pulse solution and the uniform solution are found to coexist\nin a finite range of the lattice intersite coupling where, depending on the\nlatter, one of them represents the ground state; in addition, the single-pulse\nmode does not even exist beyond a critical parametric threshold. Finally, the\nonset of the ground state (modulational) instability appears to be intimately\nconnected with a non-standard (``double transcritical'') type of bifurcation\nthat, to the best of our knowledge, has not been reported previously in other\nphysical systems."
    },
    {
        "anchor": "Scaling laws to predict humidity-induced swelling and stiffness in\n  hydrogels: From pasta to biological tissues to contact lenses, gel and gel-like\nmaterials inherently soften as they swell with water. In dry,\nlow-relative-humidity environments, these materials stiffen as they de-swell\nwith water. Here, we use semi-dilute polymer theory to develop a simple\npower-law relationship between hydrogel elastic modulus and swelling. From this\nrelationship, we predict hydrogel stiffness or swelling at arbitrary relative\nhumidities. Our close predictions of properties of hydrogels across three\ndifferent polymer mesh families at varying crosslinking densities and relative\nhumidities demonstrate the validity and generality of our understanding. This\npredictive capability enables more rapid material discovery and selection for\nhydrogel applications in varying humidity environments.",
        "positive": "Surface charge relaxation and the pearling instability of charged\n  surfactant tubes: The pearling instability of bilayer surfactant tubes was recently observed\nduring the collapse of fluid monolayers of binary mixtures of DMPC$-$POPG and\nDPPC$-$POPG surfactants. We suggested it has the same physics as the well-known\nRaleigh instability under the action of the bilayer surface tension whose\nmagnitude is dictated by the electrostatic interaction between charged\nsurfactants. In this paper, we calculate the relaxation of charge molecules\nduring the deformation of the tubes into pearling structure. We find the\nfunctional dependence of the relaxation energy on the screening length\n$\\kappa^{-1}$ explicitly. Relaxation effect lowers the cost of bending a tube\ninto pearls making the cylindrical tube even more unstable. It is known that\nfor weak screening case where the tube radius is smaller than the screening\nlength of the solution, this relaxation effect is important. However, for the\ncase of strong screening it is negligible. For the experiments mentioned, the\nsituation is marginal. In this case, we show this relaxation effect remains\nsmall. It gives less than 20% contribution to the total electrostatic energy."
    },
    {
        "anchor": "Phase diagram and melting scenarios of two-dimensional Hertzian spheres: We present computer simulations of a system of purely repulsive soft\ncolloidal particles interacting via the Hertz potential and constrained to a\ntwo-dimensional plane. This potential describes the elastic interaction of\nweakly deformable bodies and can be a reliable model for qualitative\ndescription of behavior of soft macromolecules, like globular micelles and star\npolymers. We find a large number of ordered phases, including the dodecagonal\nquasicrystal, and analyze the melting scenarios of low density triangle and\nsquare phases. It is interesting that depending on the position on the phase\ndiagram the system can melt both through the first order transition and in\naccordance with the Berezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young\n(BKTHNY) scenario (two continuous transitions with the intermediate hexatic\nphase) and also in accordance with recently proposed two-stage melting with the\nfirst order hexatic-isotropic liquid transition and continuous solid-hexatic\ntransition. We also demonstrate the possibility of the tricritical point on the\nmelting line.",
        "positive": "Ion channels in critical membranes: clustering, cooperativity, and\n  memory effects: Much progress has been made in elucidating the inner workings of\nvoltage-gated ion channels, but less understood is the influence of lipid rafts\non gating kinetics. Here we propose that state-dependent channel affinity for\ndifferent lipid species provides a unified explanation for the experimentally\nobserved behaviors of clustering, cooperativity, and hysteresis. We develop\nmodels of diffusing lipids and channels engaged in Ising-like interactions to\ninvestigate the collective behaviors driven by raft formation in critical\nmembranes close to the demixing transition. The model channels demonstrate\nlipid-mediated long-range interactions, activation curve steepening, and\nlong-term memory in ionic currents. These behaviors likely play a role in\nchannel-mediated cellular signaling and suggest a universal mechanism for\nself-organization of biomolecular assemblies."
    },
    {
        "anchor": "Aggregates of rod-coil diblock copolymers adsorbed at a surface: The behaviour of rod-coil diblock copolymers close to a surface is discussed\nby using extended scaling methods. The copolymers are immersed in selective\nsolvent such that the rods are likely to aggregate to gain energy. The rods are\nassumed to align only parallel to each other, such that they gain a maximum\nenergy by forming liquid crystalline structures. If an aggregate of these\ncopolymers adsorbs with the rods parallel to the surface the rods shift with\nrespect to each other to allow for the chains to gain entropy. It is shown that\nthis shift decays with increasing distance from the surface. The profile of\nthis decay away from the surface is calculated by minimisation of the total\nfree energy of the system. The stability of such an adsorbed aggregate and\nother possible configurations are discussed as well.",
        "positive": "Fractal aggregation of active particles: We study active run-and-tumble particles with an additional two-state\ninternal variable characterizing their motile or non-motile state. Motile\nparticles change irreversibly into non-motile ones upon collision with a\nnon-motile particle. The system evolves towards an absorbing state where all\nparticles are non-motile. We initialize the system with one non-motile\nparticles in a bath of motile ones and study numerically the kinetics of\nrelaxation to absorbing state and its structure as function of the density of\nthe initial bath of motile particles and of their tumbling rate. We find a\ncrossover from fractal aggregates at low density to homogeneous ones at high\ndensity. The persistence of single-particle dynamics as quantified by the\ntumbling rate pushes this crossover to higher density and can be used to tune\nthe porosity of the aggregate. At the lowest density the fractal dimension of\nthe aggregate approaches that obtained in single-particle diffusion limited\naggregation. Our results could be exploited for the design of structures of\ndesired porosity. The model is a first step towards the study of the collective\ndynamics of active particles that can exchange biological information."
    },
    {
        "anchor": "Dynamic Implicit-Solvent Coarse-Grained Models of Lipid Bilayer\n  Membranes : Fluctuating Hydrodynamics Thermostat: Many coarse-grained models have been developed for equilibrium studies of\nlipid bilayer membranes. To achieve in simulations access to length-scales and\ntime-scales difficult to attain in fully atomistic molecular dynamics, these\ncoarse-grained models provide a reduced description of the molecular degrees of\nfreedom and often remove entirely representation of the solvent degrees of\nfreedom. In such implicit-solvent models the solvent contributions are treated\nthrough effective interaction terms within an effective potential for the free\nenergy. For investigations of kinetics, Langevin dynamics is often used.\nHowever, for many dynamical processes within bilayers this approach is\ninsufficient since it neglects important correlations and dynamical\ncontributions that are missing as a result of the momentum transfer that would\nhave occurred through the solvent. To address this issue, we introduce a new\nthermostat based on fluctuating hydrodynamics for dynamic simulations of\nimplicit-solvent coarse-grained models. Our approach couples the coarse-grained\ndegrees of freedom to a stochastic continuum field that accounts for both the\nsolvent hydrodynamics and thermal fluctuations. We show our approach captures\nimportant correlations in the dynamics of lipid bilayers that are missing in\nsimulations performed using conventional Langevin dynamics. For both planar\nbilayer sheets and bilayer vesicles, we investigate the diffusivity of lipids,\nspatial correlations, and lipid flow within the bilayer. The presented\nfluctuating hydrodynamics approaches provide a promising way to extend\nimplicit-solvent coarse-grained lipid models for use in studies of dynamical\nprocesses within bilayers.",
        "positive": "Separation of suspended particles by arrays of obstacles in microfluidic\n  devices: The stochastic transport of suspended particles through a periodic pattern of\nobstacles in microfluidic devices is investigated by means of the Fokker-Planck\nequation. Asymmetric arrays of obstacles have been shown to induce the\ncontinuous separation of DNA molecules of different length. The analysis\npresented here of the asymptotic distribution of particles in a unit cell of\nthese systems shows that separation is only possible in the presence of a\ndriving force with a non-vanishing normal component at the surface of the solid\nobstacles. In addition, vector separation, in which different species move, in\naverage, in different directions within the device, is driven by differences on\nthe force acting on the various particles and not by differences in the\ndiffusion coefficient. Monte-Carlo simulations performed for different\nparticles and force fields agree with the numerical solutions of the\nFokker-Planck equation in the periodic system."
    },
    {
        "anchor": "Concentration Dependence of the Flory Chi Parameter within Two-State\n  Models: The Flory chi parameter is typically assumed to depend only on the\ntemperature, T. Experimental results often require the replacement of this\nchi(T) by chieff, that depends also on the monomer volume fraction, phi,\nchieff(phi,T). Such chieff(phi,T) can arise from two state-models, proposed for\npolyetheleneoxide (PEO) and other neutral water-soluble polymers. The predicted\nphi dependence of chibar=chieff-(1-phi)\\partial \\chieff/\\partial phi,\nobtainable from colligative properties, differs qualitatively between the\nvarious models: (i) The model of Karlstrom (J. Phys. Chem. 1985, 89, 4962)\nyields \\partial chibar/\\partial phi > 0 while the model of Matsuyama and Tanaka\n(Phys. Rev. Lett. 1990, 65, 341) and of Bekiranov et al (Phys. Rev. E 1997, 55,\n577) allows for \\partial chibar/\\partial phi <0 (ii) chibar(phi) as calculated\nfrom the Karlstrom model, utilizing the parameters used to fit the phase\ndiagram of PEO, agrees semiquantitatively with the experimental values. On the\nother hand, chibar(phi) similarly calculated from the model of Bekiranov et al.\ndiffers qualitatively from the measured results. Altogether, chibar(phi)\nprovides useful measure for the performance of a model.",
        "positive": "Signatures of Incipient Jamming in Collisional Hopper Flows: Many disordered systems experience a transition from a fluid-like state to a\nsolid-like state following a sudden arrest in dynamics called jamming. In\ncontrast to jamming in spatially homogeneous systems, jamming in hoppers occurs\nunder extremely inhomogeneous conditions as the gravity-driven flow of grains\nenclosed by rigid walls converges towards a small opening. In this work, we\nstudy velocity fluctuations in a collisional flow near jamming using\nevent-driven simulations. The average flow in a hopper geometry is known to\nhave strong gradients, especially near the walls and the orifice. We find, in\naddition, a spatially heterogeneous distribution of fluctuations, most striking\nin the velocity autocorrelation relaxation times. At high flow rates, the flow\nat the center has lower kinetic temperatures and longer autocorrelation times\nthan at the boundary. Remarkably, however, this trend reverses itself as the\nflow rate slows, with fluctuations relaxing more slowly at the boundaries\nthough the kinetic temperatures remain high in that region. The slowing down of\nthe dynamics is accompanied by increasing non-Gaussianity in the velocity\ndistributions, which also have large spatial variations."
    },
    {
        "anchor": "Competing Alignments of Nematic Liquid Crystals on Square Patterned\n  Substrates: A theoretical analysis is presented of a nematic liquid crystal confined\nbetween substrates pat- terned with squares that promote vertical and planar\nalignment. Two approaches are used to eluci- date the behavior across a wide\nrange of length scales: Monte Carlo simulation of hard particles and\nFrank-Oseen continuum theory. Both approaches predict bistable degenerate\nazimuthal alignment in the bulk along the edges of the squares; the continuum\ncalculation additionally reveals the possi- bility of an anchoring transition\nto diagonal alignment if the polar anchoring energy associated with the pattern\nis sufficiently weak. Unlike the striped systems previously analyzed, the Monte\nCarlo simulations suggest that there is no \"bridging\" transition for\nsufficiently thin cells. The extent to which these geometrically patterned\nsystems resemble topographically patterned substrates, such as square wells, is\nalso discussed.",
        "positive": "Compositeness Effects in the Bose-Einstein Condensation: Small deviations from purely bosonic behavior of trapped atomic Bose-Einstein\ncondensates are investigated with the help of the quon algebra, which\ninterpolates between bosonic and fermionic statistics. A previously developed\nformalism is employed to obtain a generalized version of the Gross-Pitaeviskii\nequation. Two extreme situations are considered, the collapse of the condensate\nfor attractive forces and the depletion of the amount of condensed atoms with\nrepulsive forces. Experimental discrepancies observed in the parameters\ngoverning the collapse and the depletion of the condensates can be accounted\nfor by universal fittings of the deformation parameter for each case."
    },
    {
        "anchor": "Predicting scaling properties from a single fluid configuration: Time-dependent dynamical properties of a fluid can not be estimated from a\nsingle configuration without performing a simulation. Here we show, however,\nthat the scaling properties of both structure and dynamics can be predicted\nfrom a single configuration. The new method is demonstrated to work very well\nfor equilibrium dynamics of the Kob-Andersen Binary Lennard-Jones mixture.\nFurthermore, the method is applied to isobaric cooling where the liquid falls\nout of equilibrium and forms a glass, demonstrating that the method requires\nneither equilibrium nor constant volume conditions to work, in contrast to\nexisting methods.",
        "positive": "Swollen Micelles Plus Hydrophobically Modified Hydrosoluble Polymers in\n  Aqueous Solutions: Decoration Versus Bridging. a Small Angle Neutron\n  Scattering Study: In this paper we examine the effective interactions introduced between the\ndroplets of an oil in water microemulsion upon progressive addition of\nhydrophobically modified water soluble poly(ethylene oxide)-PEO using\nessentially small angle neutron scattering. To discuss the relative importance\nof decoration and bridging of the droplets we compare analogous samples with\naddition of a PEO grafted at both extremities with hydrophobic C12H 25 chains\n(PEO-2m) or addition of a PEO grafted at one extremity only with a C12H 25\nchain (PEO-m). PEO-m or PEO-2m adsorb onto the droplets via their hydrophobic\nextremities and the droplets are found to retain their form and size upon\naddition of up to 40 hydrophobic C12H 25 chains per droplet. When the volume\nfraction of droplets is less than about 10%, the effective interactions\nintroduced by PEO-m or PEO-2m are found to be very different: PEO-m introduces\na repulsive interaction while PEO-2m introduces an effective attractive\ninteraction. This attractive interaction leads to an associative phase\nseparation in the range of low volume fraction when a sufficient amount of\nPEO-2m is added."
    },
    {
        "anchor": "The Interfacial-Organized Monolayer Water Hindering the Aggregation of\n  Nanographene: Both in Stacking and Sliding Assembly Pathways: A computational investigation was carried out to understand the aggregation\nof nanoscale graphene with two typical assembly pathways of stacking assembly\nand sliding assembly in water. The interfacial-organized monolayer water film\n(MWF) hindering the aggregation of nanographene in both stacking and sliding\nassembly pathways was reported for the first time. By means of potential mean\nforces (PMFs) calculation, no energy barrier was observed during the sliding\nassembly of two graphene nanosheets, while the PMF profiles could be impacted\nby the contact forms of nanographene and the MWF within the interplate of two\ngraphene nanosheets. To explore the potential physical basis of the\nhindering-role of self-organized interfacial water, the dynamical and\nstructural properties as well as the status of hydrogen bonds (H-bonds) for\ninterfacial water were investigated. We found that the compact, ordered\nstructure and abundant H-bonds of the MWF could be taken as the fundamental\naspects of the hindering-role of interfacial water for the hydrophobic assembly\nof nanographene. These findings are displaying a potential to further\nunderstand the hydrophobic assembly which mostly dominate the behaviors of\nnanomaterials, proteins etc. in aqueous solutions.",
        "positive": "Critical Casimir forces between planar and crenellated surfaces: We study critical Casimir forces between planar walls and geometrically\nstructured substrates within mean-field theory. As substrate structures,\ncrenellated surfaces consisting of periodic arrays of rectangular crenels and\nmerlons are considered. Within the widely used proximity force approximation,\nboth the top surfaces of the merlons and the bottom surfaces of the crenels\ncontribute to the critical Casimir force. However, for such systems the full,\nnumerically determined critical Casimir forces deviate significantly fromthe\npairwise addition formalismunderlying the proximity force approximation. A\nfirst-order correction to the proximity force approximation is presented in\nterms of a step contribution arising from the critical Casimir interaction\nbetween a planar substrate and the right-angled steps of the merlons consisting\nof their upper and lower edges as well as their sidewalls."
    },
    {
        "anchor": "Excitable reaction-diffusion waves of curvature-inducing proteins on\n  deformable membrane tubes: Living cells employ excitable reaction-diffusion waves for internal cellular\nfunctions, in which curvature-inducing proteins are often involved. However,\nthe role of their mechanochemical coupling is not well understood. Here, we\nreport the membrane deformation induced by the excitable reaction-diffusion\nwaves of curvature-inducing proteins and the alternation in the waves due to\nthe deformation, using a coarse-grained simulation of tubular membranes with a\nmodified FitzHugh--Nagumo model. Protein-propagating waves deform tubular\nmembranes, and large deformations induce budding and erase waves. The wave\nspeed and shape are determined by a combination of membrane deformation and\nspatial distribution of the curvature-inducing protein. Waves are also\nundulated in the azimuthal direction depending on the condition. Rotationally\nsymmetric waves locally deform the tubes into a symmetric shape but maintain a\nstraight shape on average. Our simulation method can be applied to other\nchemical reaction models and used to investigate various biomembrane phenomena.",
        "positive": "Systematic characterization of thermodynamic and dynamical phase\n  behavior in systems with short-ranged attraction: In this paper we demonstrate the feasibility and utility of an augmented\nversion of the Gibbs ensemble Monte Carlo method for computing the phase\nbehavior of systems with strong, extremely short-ranged attractions. For\ngeneric potential shapes, this approach allows for the investigation of\nnarrower attractive widths than those previously reported. Direct comparison to\nprevious self-consistent Ornstein-Zernike approximation calculations are made.\nA preliminary investigation of out-of-equilibrium behavior is also performed.\nOur results suggest that the recent observations of stable cluster phases in\nsystems without long-ranged repulsions are intimately related to gas-crystal\nand metastable gas-liquid phase separation."
    },
    {
        "anchor": "Mixtures of functionalized colloids on substrates: Patchy particles are a class of colloids with functionalized surfaces.\nThrough surface functionalization, the strength and directionality of the\ncolloidal interactions are tunable allowing control over coordination of the\nparticle. Exquisite equilibrium phase diagrams of mixtures of coordination two\nand three have been reported. However, the kinetics of self-organization and\nthe feasibility of the predicted structures are still largely unexplored. Here,\nwe study the irreversible aggregation of these mixtures on a substrate, for\ndifferent fractions of two-patch particles. Two mechanisms of mass transport\nare compared: diffusion and advection. In the diffusive case, an optimal\nfraction is found that maximizes the density of the aggregate. By contrast, for\nadvective transport, the density decreases monotonically with the fraction of\ntwo-patch colloids, in line with the behavior of the liquid density on the\nspinodal of the equilibrium phase diagram.",
        "positive": "Transition from single-file to two-dimensional diffusion of interacting\n  particles in a quasi-one-dimensional channel: Diffusive properties of a monodisperse system of interacting particles\nconfined to a \\textit{quasi}-one-dimensional (Q1D) channel are studied using\nmolecular dynamics (MD) simulations. We calculate numerically the mean-squared\ndisplacement (MSD) and investigate the influence of the width of the channel\n(or the strength of the confinement potential) on diffusion in finite-size\nchannels of different shapes (i.e., straight and circular). The transition from\nsingle-file diffusion (SFD) to the two-dimensional diffusion regime is\ninvestigated. This transition (regarding the calculation of the scaling\nexponent ($\\alpha$) of the MSD $<\\Delta x^{2}(t)>$ $\\propto t^{\\alpha}$) as a\nfunction of the width of the channel, is shown to change depending on the\nchannel's confinement profile. In particular the transition can be either\nsmooth (i.e., for a parabolic confinement potential) or rather sharp/stepwise\n(i.e., for a hard-wall potential), as distinct from infinite channels where\nthis transition is abrupt. This result can be explained by qualitatively\ndifferent distributions of the particle density for the different confinement\npotentials."
    },
    {
        "anchor": "Relaxation of surface tension in the liquid-solid interfaces of\n  Lennard-Jones liquids: We have established the surface tension relaxation time in the liquid-solid\ninterfaces of Lennard-Jones (LJ) liquids by means of direct measurements in\nmolecular dynamics (MD) simulations. The main result is that the relaxation\ntime is found to be weakly dependent on the molecular structures used in our\nstudy and lies in such a range that in slow hydrodynamic motion the interfaces\nare expected to be at equilibrium. The implications of our results for the\nmodelling of dynamic wetting processes and interpretation of dynamic contact\nangle data are discussed.",
        "positive": "Non-monotonic Mpemba effect in binary molecular suspensions: The Mpemba effect is a phenomenon in which an initially hotter sample cools\nsooner. In this paper, we show the emergence of a non-monotonic Mpemba-like\neffect in a molecular binary mixture immersed in a viscous gas. Namely, a\ncrossover in the temperature evolution when at least one of the samples\npresents non-monotonic relaxation. The influence of the bath on the dynamics of\nthe particles is modeled via a viscous drag force plus a stochastic\nLangevin-like term. Each component of the mixture interchanges energy with the\nbath depending on the mechanical properties of its particles. This\ndiscrimination causes the coupling between the time evolution of temperature\nwith that of the partial temperatures of each component. The non-monotonic\nMpemba effect -- and its inverse and mixed counterparts -- stems from this\ncoupling. In order to obtain analytical results, the velocity distribution\nfunctions of each component are approximated by considering multitemperature\nMaxwellian distributions. The theoretical results derived from the Enskog\nkinetic theory show an excellent agreement with direct simulation Monte Carlo\n(DMSC) data."
    },
    {
        "anchor": "Designing a braille reader using the snap buckling of bistable magnetic\n  shells: A design concept is introduced for the building block, a dot, of programmable\nbraille readers utilizing bistable shell buckling, magnetic actuation, and\npneumatic loading. The design process is guided by Finite Element simulations,\nwhich are initially validated through precision experiments conducted on a\nscaled-up, single-shell model system. Then, the simulations are leveraged to\nsystematically explore the design space, adhering to the standardized geometric\nand physical specifications of braille systems. The findings demonstrate the\nfeasibility of selecting design parameters that satisfy both geometric\nrequirements and blocking forces under moderate magnetic fields, facilitated by\npneumatic loading to switch between the two stable states. The advantages of\nthe proposed design include the reversible bistability of the actuators and\nfast state-switching via a transient magnetic field. While the study is focused\non experimentally validated numerical simulations, several manufacturing\nchallenges that need to be resolved for future physical implementations are\nidentified.",
        "positive": "Soft modes in jammed hard spheres (I): Mean field theory of the\n  isostatic transition: In this paper we consider different models for soft modes in jammed hard\nspheres. We show how one can construct mean field models that can be solved\nanalytically. The analytic solution of these models displays an excess of low\nenergy soft modes that become more and more localized by decreasing the energy.\nA simple solution of these models is found in the infinite dimensional limit."
    },
    {
        "anchor": "Hydrodynamics of Binary Fluid Mixtures - An Augmented Multiparticle\n  Collison Dynamics Approach: The Multiparticle Collision Dynamics technique (MPC) for hydrodynamics\nsimulations is generalized to binary fluid mixtures and multiphase flows, by\ncoupling the particle-based fluid dynamics to a Ginzburg-Landau free-energy\nfunctional for phase-separating binary fluids. To describe fluids with a\nnon-ideal equation of state, an additional density-dependent term is\nintroduced. The new approach is verified by applying it to thermodynamics near\nthe critical demixing point, and interface fluctuations of droplets. The\ninterfacial tension obtained from the analysis of the capillary wave spectrum\nagrees well with the results based on the Laplace-Young equation.\nPhase-separation dynamics follows the Lifshitz-Slyozov law.",
        "positive": "Electric double layer of colloidal particles in salt-free concentrated\n  suspensions including non-uniform size effects and orientational ordering of\n  water dipoles: The response of a suspension under a variety of static or alternating\nexternal fields strongly depends on the equilibrium electric double layer that\nsurrounds the colloidal particles in the suspension. The theoretical models for\nsalt-free suspensions can be improved by incorporating non-uniform size effects\nand orientational ordering of water dipoles neglected in previous mean-field\napproaches, which are based on the Poisson-Boltzmann approach. Our model\nincluding non-uniform size effects and orientational ordering of water dipoles\nseems to have quite a promising effect because the model can predict the\nphenomena like a heavy decrease in relative permittivity of the suspension and\ncounterion stratification near highly charged colloidal particle. In this work\nwe numerically obtain the electric potential, the counterions concentration and\nthe relative permittivity around a charged particle in a concentrated salt-free\nsuspension corrected by non-uniform size effects and orientational ordering of\nwater dipoles. The results show the worth of such corrections for medium to\nhigh particle charges at every particle volume fraction. We conclude that\nnon-uniform size effects and orientational ordering of water dipoles are\nnecessary for the development of new theoretical models to study\nnon-equilibrium properties in concentrated colloidal suspensions."
    },
    {
        "anchor": "Laser induced freezing of charge stabilized colloidal system: We present results from an extensive simulational study of the modulated\nliquid $\\longleftrightarrow$ crystal transition in a 2-d charge-stabilized\ncolloid subject to a 1-d laser field modulation commensurate with the\ncrystalline phase. {\\em {Contrary to some earlier simulational and experimental\nfindings we do not find any reentrant liquid phase in our simulation.\nFurthermore the transition remains first-order (albeit weak, with a fairly\nlarge correlation length) even in the limit of infinite field, contrary to\nmean-field predictions}}. In the modulated liquid phase, while the\ntranslational order decays exponentially, the bond orientational order is\nactually long ranged.",
        "positive": "A lattice Boltzmann study of particle settling in a fluctuating\n  multicomponent fluid under confinement: We present mesoscale numerical simulations based on the coupling of the\nfluctuating lattice Boltzmann method (FLBM) for multicomponent systems with a\nwetted finite-size particle model. This newly coupled methodologies are used to\nstudy the motion of a spherical particle driven by a constant body force in a\nconfined channel with a fixed square cross-section. The channel is filled with\na mixture of two liquids under the effect of thermal fluctuations. After some\nvalidations steps in absence of fluctuations, we study the fluctuations in the\nparticle's velocity at changing thermal energy, applied force, particle size,\nand particle wettability. The importance of fluctuations with respect to the\nmean settling velocity is quantitatively assessed, especially in comparison to\nunconfined situations. Results show that the expected effects of confinement\nare very well captured by the numerical simulations, wherein the confinement\nstrongly enhances the importance of velocity fluctuations, which can be one\norder of magnitude larger than what expected in unconfined domains. The\nobserved findings underscore the versatility of the proposed methodology in\nhighlighting the effects of confinement on the motion of particles in presence\nof thermal fluctuations."
    },
    {
        "anchor": "A kinetic approach to active rod dynamics in confined domains: The study of active matter consisting of many self-propelled (active)\nswimmers in an imposed flow is important for many applications. Self-propelled\nswimmers may represent both living and artificial ones such as bacteria and\nchemically driven bi-metallic nano-particles. In this work we focus on a\nkinetic description of active matter represented by self-propelled rods\nswimming in a viscous fluid confined by a wall. It is well-known that walls may\nsignificantly affect the trajectories of active rods in contrast to unbounded\nor periodic containers. Among such effects are accumulation at walls and\nupstream motion (also known as negative rheotaxis). Our first main result is\nthe rigorous derivation of boundary conditions for the active rods' probability\ndistribution function in the limit of vanishing inertia. Finding such a limit\nis important due to (i) the fact that in many examples of active matter inertia\nis negligible, since swimming occurs in a low Reynolds number regime, and (ii)\nthis limit allows us to reduce the dimension - and so computational complexity\n- of the kinetic description. For the resulting model, we derive the system in\nthe limit of vanishing translational diffusion which is also typically\nnegligible for active particles. This system allows for tracking separately\nactive particles accumulated at walls and active particles swimming in the bulk\nof the fluid.",
        "positive": "Microphase separation in neutral homopolymer blends induced by\n  salt-doping: Microphase separation in polymeric systems provides a bottom-up strategy to\nfabricate nanostructures. Polymers that are reported to undergo microphase\nseparation usually include block copolymers or polyelectrolytes. Neutral\nhomopolymers, which are comparatively easy to synthesize, are thought to be\nincapable of microphase separation. Here, using a minimal model that accounts\nfor ion solvation, we show that microphase separation is possible in neutral\nhomopolymer blends with sufficient dielectric contrast, upon a tiny amount of\nsalt-doping. The driving force for the microphase separation is the competition\nbetween selective ion solvation, which places smaller ions in domains with\nhigher dielectric constant, and the propensity for local charge neutrality to\ndecrease the electrostatic energy. The compromise is an emergent length over\nwhich microphase separation occurs and ions are selectively solvated. The\nfactors affecting such competitions are explored, including ion solvation\nradii, dielectric contrast, and polymer fraction, which point to directions for\nobserving this behavior experimentally. These findings suggest a low-cost and\nfacile alternative to produce microphase separation which may be exploited in\nadvanced material design and preparation."
    },
    {
        "anchor": "Limited Perturbation of a DPPC Bilayer by Fluorescent Lipid Probes: A\n  Molecular Dynamics Study: The presence and the properties of lipid bilayer nanometer-scale domains\nmight be important for understanding the membranes of living cells. We used\nmolecular dynamics (MD) simulations to investigate perturbations of a small\npatch of fluid-phase DPPC bilayer upon incorporation of fluorescent\nindocarbocyanine lipid probes commonly used to study membranes (DiI-C12:0,\nDiI-C18:0, or DiI-C18:2). In simulations containing 1 probe per 64 total lipids\nin each leaflet, an 8 - 12% decrease in chain order is observed for DPPC\nmolecules in the solvation shell closest to the probe, relative to a pure DPPC\nbilayer. A ~5% increase in chain order is seen in the next three shells,\nresulting in a small overall increase in average DPPC chain order. In\nsimulations with 1 probe per 256 total lipids in each leaflet, average DPPC\nchain order is unaffected by the probe. Thus, these DiI probes cause an\noscillatory perturbation of their local environment but do not strongly\ninfluence the average properties of even \"nanoscopic\" lipid phase domains.",
        "positive": "Two-dimensional Vesicle dynamics under shear flow: effect of confinement: Dynamics of a single vesicle under shear flow between two parallel plates is\nstudied using two-dimensional lattice-Boltzmann simulations. We first present\nhow we adapted the lattice-Boltzmann method to simulate vesicle dynamics, using\nan approach known from the immersed boundary method. The fluid flow is computed\non an Eulerian regular fixed mesh while the location of the vesicle membrane is\ntracked by a Lagrangian moving mesh. As benchmarking tests, the known vesicle\nequilibrium shapes in a fluid at rest are found and the dynamical behavior of a\nvesicle under simple shear flow is being reproduced. Further, we focus on\ninvestigating the effect of the confinement on the dynamics, a question that\nhas received little attention so far. In particular, we study how the vesicle\nsteady inclination angle in the tank-treading regime depends on the degree of\nconfinement. The influence of the confinement on the effective viscosity of the\ncomposite fluid is also analyzed. At a given reduced volume (the swelling\ndegree) of a vesicle we find that both the inclination angle, and the membrane\ntank-treading velocity decrease with increasing confinement. At sufficiently\nlarge degree of confinement the tank-treading velocity exhibits a\nnon-monotonous dependence on the reduced volume and the effective viscosity\nshows a nonlinear behavior."
    },
    {
        "anchor": "Simulating the pitch sensitivity of twisted nematics of patchy rods: Stiff, elongated biomolecules such as filamentous viruses, DNA or cellulose\nnanocrystals are known to form liquid crystals often exhibiting a helical\nsupramolecular organization. Little is known about the microscopic origin, size\nand handedness of the helical pitch in these, so-called cholesteric phases.\nExperimental observations in chiral lyotropics suggest that long-ranged chiral\nforces of electrostatic origin acting between the mesogens are responsible for\nsuch organization. Using large-scale computer simulation we study the\nsensitivity of the pitch imparted by soft microscopic helices and confirm that\nthe helical sense is sensitive to a change of packing fraction, magnitude of\nthe molecular pitch and amplitude of the chiral interactions. In particular, we\nfind evidence that the cholesteric helix sense may change spontaneously upon\nvariation of particle density, at fixed molecular chirality. These pitch\ninversions have been reported in recent theoretical studies but simulation\nevidence remains elusive. We rationalize these sudden changes in the\nsupramolecular helical symmetry on the basis of detailed measurements of the\nmean-torque generated by the twisting of the helices. The simulation\nmethodology employed does not require confining the twisted nematic in a slab\ngeometry and allows for a simultaneous measurement of the pitch and the twist\nelastic constant. We find that the twist elastic constant increases almost\nlinearly with density suggesting that twisted nematic shows no signs of\nanomalous stiffening due to pre-smectic fluctuations at higher packing\nfraction.",
        "positive": "Long-wavelength deformations and vibrational modes in empty and\n  liquid-filled microtubules and nanotubes: A theoretical study: We propose a continuum model to predict long-wavelength vibrational modes of\nempty and liquid-filled tubules that are very hard to reproduce using the\nconventional force-constant matrix approach based on atomistic ab initio\ncalculation. We derive simple quantitative expressions for long-wavelength\nlongitudinal and torsional acoustic modes, flexural acoustic modes, as well as\nthe radial breathing mode of empty or liquid-filled tubular structures that are\nbased on continuum elasticity theory expressions for a thin elastic plate. We\nfurthermore show that longitudinal and flexural acoustic modes of tubules are\nwell described by those of an elastic beam resembling a nanowire. Our numerical\nresults for biological microtubules and carbon nanotubes agree with available\nexperimental data."
    },
    {
        "anchor": "Modeling of nematic electrolyte and nonlinear electroosmosis: We derive a mathematical model of a nematic electrolyte based on the\nLeslie-Ericksen theory of liquid crystal flow. Our goal is to investigate the\nnonlinear electrokinetic effects that occur because the nematic matrix is\nanisotropic, in particular, transport of ions in a direction perpendicular to\nthe electric field as well as quadratic dependence of the induced flow velocity\non the electric field. The latter effect makes it possible to generate\nsustained flows in the nematic electrolyte that do not reverse their direction\nwhen the polarity of the applied electric field is reversed. From a practical\nperspective, this enables the design of AC-driven electrophoretic and\nelectroosmotic devices. Our study of a special flow in a thin nematic film\nshows a very good agreement with laboratory experiments.",
        "positive": "Discontinuous shear-thickening in Brownian suspensions: Discontinuous shear-thickening in dense suspensions naturally emerges from\nthe activation of frictional forces by shear flow in non-Brownian systems close\nto jamming. Yet, this physical picture is incomplete as most experiments study\nsoft colloidal particles subject to thermal fluctuations. To characterise\ndiscontinuous shear-thickening in colloidal suspensions we use computer\nsimulations to provide a complete description of the competition between\nathermal jamming, frictional forces, thermal motion, particle softness, and\nshear flow. We intentionally neglect hydrodynamics, electrostatics,\nlubrication, and inertia, but can nevertheless achieve quantitative agreement\nwith experimental findings. In particular, shear-thickening corresponds to a\ncrossover between frictionless and frictional jamming regimes which is\ncontrolled by thermal fluctuations and particle softness and occurs at a\nsoftness dependent P\\'eclet number. We also explore the consequences of our\nfindings for constant pressure experiments, and critically discuss the reported\nemergence of `S-shaped' flow curves. Our work provides the minimal ingredients\nto quantitatively interpret a large body of experimental work on discontinuous\nshear-thickening in colloidal suspensions."
    },
    {
        "anchor": "Diffusiophoretic design of self-spinning microgears from colloidal\n  microswimmers: Design strategies to assemble dissipative building blocks are essential to\ncreate novel and smart materials and machines. We recently demonstrated the\nhierarchical self-assembly of phoretic microswimmers into self-spinning\nmicrogears and their synchronization by diffusiophoretic interactions [Aubret\n\\textit{et al., Nature Physics}, 2018]. In this paper, we adopt a pedagogical\napproach and expose our strategy to control self-assembly and build machines\nusing phoretic phenomena. We notably introduce Highly Inclined Laminated\nOptical sheets microscopy (HILO) to image and quantify anisotropic and dynamic\ndiffusiophoretic interactions, which could not be observed by standard\nfluorescence microscopy. The dynamics of a (haematite) photocalytic material\nimmersed in (hydrogen peroxide) fuel under various illumination patterns is\nfirst described and quantitatively rationalized by a model of diffusiophoresis,\nthe migration of a colloidal particle in a concentration gradient. It is\nfurther exploited to design phototactic microswimmers, that direct towards the\nhigh intensity of light, as a result of the the torque exerted by the haematite\nin a light gradient on a microswimmer. We finally demonstrate the assembly of\nself-spinning microgears from colloidal microswimmers by controlling\ndissipative diffusiophoretic interactions, that we characterize using HILO and\nquantitatively compare to analytical and numerical predictions. Because the\napproach described hereby is generic, this works paves the way for the rational\ndesign of machines by controlling phoretic phenomena.",
        "positive": "Effective forces in colloidal mixtures: from depletion attraction to\n  accumulation repulsion: Computer simulations and theory are used to systematically investigate how\nthe effective force between two big colloidal spheres in a sea of small spheres\ndepends on the basic (big-small and small-small) interactions. The latter are\nmodeled as hard-core pair potentials with a Yukawa tail which can be both\nrepulsive or attractive. For a repulsive small-small interaction, the effective\nforce follows the trends as predicted by a mapping onto an effective\nnon-additive hard-core mixture: both a depletion attraction and an accumulation\nrepulsion caused by small spheres adsorbing onto the big ones can be obtained\ndepending on the sign of the big-small interaction. For repulsive big-small\ninteractions, the effect of adding a small-small attraction also follows the\ntrends predicted by the mapping. But a more subtle ``repulsion through\nattraction'' effect arises when both big-small and small-small attractions\noccur: upon increasing the strength of the small-small interaction, the\neffective potential becomes more repulsive. We have further tested several\ntheoretical methods against our computer simulations: The superposition\napproximation works best for an added big-small repulsion, and breaks down for\na strong big-small attraction, while density functional theory is very accurate\nfor any big-small interaction when the small particles are pure hard-spheres.\nThe theoretical methods perform most poorly for small-small attractions."
    },
    {
        "anchor": "Influence of contact angle on slow evaporation in two-dimensional porous\n  media: We study numerically the influence of contact angle on slow evaporation in\ntwo-dimensional model porous media. For sufficiently low contact angles, the\ndrying pattern is fractal and can be predicted by a simple model combining the\ninvasion percolation model with the computation of the diffusive transport in\nthe gas phase. The overall drying time is minimum in this regime and is\nindependent of contact angle over a large range of contact angles up to the\nbeginning of a transition zone. As the contact angle increases in the\ntransition region, the cooperative smoothing mechanisms of the interface become\nimportant and the width of the liquid gas interface fingers that form during\nthe evaporation process increases. The mean overall drying time increases in\nthe transition region up to an upper bound which is reached at a critical\ncontact angle \\Theta_c. The increase in the drying time in the transition\nregion is explained in relation with the diffusional screening phenomenon\nassociated with the Laplace equation governing the vapor transport in the gas\nphase. Above \\Theta_c the drying pattern is character- ized by a flat traveling\nfront and the mean overall drying time becomes independent of the contact\nangle. Drying time fluctuations are studied and are found to be important below\n\\Theta_c, i.e., when the pattern is fractal. The fluctuations are of the same\norder of magnitude regardless of the value of contact angle in this range. The\nfluctuations are found to die out abruptly at \\Theta_c as the liquid gas\ninterface becomes a flat front.",
        "positive": "Dielectric behaviour of graded spherical cells with an intrinsic\n  dispersion: The dielectric properties of single-shell spherical cells with an intrinsic\ndielectric dispersion has been investigated. By means of the dielectric\ndispersion spectral representation (DDSR) for the Clausius-Mossotti (CM)\nfactor, we express the dispersion strengths as well as the characteristic\nfrequencies of the CM factor analytically in terms of the parameters of the\ncell model. These analytic expressions enable us to assess the influence of\nvarious model parameters on the electrokinetics of cells. Various interesting\nbehaviours have been reported. We extend our considerations to a more realistic\ncell model with a graded core, which can have spatial gradients in the\nconductivity and/or permittivity. To this end, we address the effects of a\ngraded profile in a small-gradient expansion in the framework of DDSR."
    },
    {
        "anchor": "Hydrodynamic interactions induce anomalous diffusion under partial\n  confinement: Under partial confinement, the motion of colloidal particles is restricted to\na plane but their dynamics is influenced by hydrodynamic interactions mediated\nby the unconfined, three--dimensional flow of the embedding fluid. We\ndemonstrate that this dimensionality mismatch induces a characteristic\ndivergence in the two--dimensional collective diffusion coefficient of the\ncolloidal monolayer. This result, independent from the specific interparticle\nforces in the monolayer, is solely due to the kinematical constraint on the\ncolloidal particles, and it is different from the known divergence of transport\ncoefficients in purely two--dimensional fluids.",
        "positive": "A characteristic energy scale in glasses: Glasses feature a broad distribution of relaxation times and activation\nenergies without an obvious characteristic scale. At the same time, macroscopic\nquantities such as Newtonian viscosity and nonlinear plastic deformation, are\ninterpreted in terms of a characteristic energy scale, e.g. an effective\ntemperature-dependent activation energy in Arrhenius relations. Nevertheless,\ndespite its fundamental importance, such a characteristic energy scale has not\nbeen robustly identified. Inspired by the accumulated evidence regarding the\ncrucial role played by soft quasilocalized excitations in glassy dynamics, we\npropose that the bulk average of the glass response to a localized force dipole\ndefines such a characteristic energy scale. We show that this characteristic\nglassy energy scale features remarkable properties: $(i)$ It increases\ndramatically with decreasing temperature of equilibrium supercooled states,\nsignificantly surpassing the corresponding increase in the shear modulus,\ndismissing the common view that structural variations in supercooled liquids\nupon vitrification are minute $(ii)$ Its variation with annealing and system\nsize is very similar in magnitude and form to that of the energy of the softest\nnon-phononic vibrational mode, thus establishing a very unusual relation\nbetween a rare glassy fluctuation and a bulk average $(iii)$ It exhibits\nstriking dependence on spatial dimensionality and system size, due to the\nlong-ranged fields associated with quasilocalization, which are speculated to\nbe related to peculiarities of the glass transition in two dimensions. In\naddition, we identify a truly-static growing lengthscale associated with the\ncharacteristic glassy energy scale, and discuss possible connections between\nthe increase of this energy scale and the slowing down of dynamics near the\nglass transition temperature. Open questions and future directions are\ndiscussed."
    },
    {
        "anchor": "Electrostatics and aggregation: how charge can turn a crystal into a gel: The crystallization of proteins or colloids is often hindered by the\nappearance of aggregates of low fractal dimension called gels. Here we study\nthe effect of electrostatics upon crystal and gel formation using an analytic\nmodel of hard spheres bearing point charges and short range attractive\ninteractions. We find that the chief electrostatic free energy cost of forming\nassemblies comes from the entropic loss of counterions that render assemblies\ncharge-neutral. Because there exists more accessible volume for these\ncounterions around an open gel than a dense crystal, there exists an\nelectrostatic entropic driving force favoring the gel over the crystal. This\ndriving force increases with increasing sphere charge, but can be counteracted\nby increasing counterion concentration. We show that these effects cannot be\nfully captured by pairwise-additive macroion interactions of the kind often\nused in simulations, and we show where on the phase diagram to go in order to\nsuppress gel formation.",
        "positive": "Thermomechanical surface instability at the origin of surface fissure\n  patterns on heated circular MDF samples: When a flat sample of medium density fibreboard (MDF) is exposed to radiant\nheat in an inert atmosphere, primary crack patterns suddenly start to appear\nover the entire surface before pyrolysis and any charring occurs. Contrary to\ncommon belief that crack formation is due to drying and shrinkage, it was\ndemonstrated for square samples that this results from thermomechanical\ninstability.\n  In the present paper, new experimental data are presented for circular\nsamples of the same MDF material. The sample was exposed to radiant heating at\n20 or 50 kW/m2, and completely different crack patterns with independent\nEigenmodes were observed at the two heat fluxes. We show that the two patterns\ncan be reproduced with a full 3-D thermomechanical surface instability model of\na hot layer adhered to an elastic colder foundation in an axisymmetric domain.\nAnalytical and numerical solutions of a simplified 2-D formulation of the same\nproblem provide excellent qualitative agreement between observed and calculated\npatterns.\n  Previous data for square samples together with the results reported in the\npresent paper for circular samples confirm the validity of the model for\nqualitative predictions, and indicate that further refinements can be made to\nimprove its quantitative predictive capability."
    },
    {
        "anchor": "Twisting and Bending Stress in DNA Minicircles: The interplay between bending of the molecule axis and appearance of\ndisruptions in circular DNA molecules, with $\\sim 100$ base pairs, is\naddressed. Three minicircles with different radii and almost equal content of\nAT and GC pairs are investigated. The DNA sequences are modeled by a mesoscopic\nHamiltonian which describes the essential interactions in the helix at the\nlevel of the base pair and incorporates twisting and bending degrees of\nfreedom. Helix unwinding and bubble formation patterns are consistently\ncomputed by a path integral method that sums over a large number of molecule\nconfigurations compatible with the model potential. The path ensembles are\ndetermined, as a function of temperature, by minimizing the free energy of the\nsystem. Fluctuational openings appear along the helix to release the stress due\nto the bending of the molecule backbone. In agreement with the experimental\nfindings, base pair disruptions are found with larger probability in the\nsmallest minicircle of \\textit{66-bps} whose bending angle is $\\sim 6^{o} $.\nFor this minicircle, a sizeable untwisting is obtained with the helical repeat\nshowing a step-like increase at $\\tau =\\,315K$. The method can be generalized\nto determine the bubble probability profiles of open ends linear sequences.",
        "positive": "Possibility of Gravitational Tempering in Colloidal Epitaxy to Obtain a\n  Perfect Crystal: We have performed Monte Carlo simulations of hard spheres on a pattern under\ngravity. We have found that a crystal formed at a moderate gravity strength\ncontains essentially no defects while one formed at a higher strength gravity\ncontains a significant amount of defects. This result suggests the possibility\nof using gravitational-tempering in a colloidal epitaxy to reduce the number of\ndefects in colloidal crystals. Moreover, we wish to emphasize the possibility\nto obtain a perfect crystal."
    },
    {
        "anchor": "Stress Correlations in Frictional Granular Media: This paper investigates whether in frictional granular packings, like in\nHamiltonian amorphous elastic solids, the stress autocorrelation matrix\npresents long range anisotropic contributions just as elastic Green's\nfunctions. We find that in a standard model of frictional granular packing this\nis not the case. We prove quite generally that mechanical balance and material\nisotropy constrain the stress auto-correlation matrix to be fully determined by\ntwo spatially isotropic functions: the pressure and torque auto-correlations.\nThe pressure and torque fluctuations being respectively normal and hyperuniform\nforce the stress autocorrelation to decay as the elastic Green's function.\nSince we find the torque fluctuations to be hyper-uniform, the culprit is the\npressure whose fluctuations decay slower than normally as a function of the\nsystem's size. Investigating the reason for these abnormal pressure\nfluctuations we discover that anomalous correlations build up already during\nthe compression of the dilute system before jamming. Once jammed these\ncorrelations remain frozen. Whether this is true for frictional matter in\ngeneral or is it the consequence of the model properties is a question that\nmust await experimental scrutiny and possible alternative models.",
        "positive": "Anomalous system-size dependence of electrolytic cells with an\n  electrified oil-water interface: Manipulation of the charge of the dielectric interface between two bulk\nliquids not only enables the adjustment of the interfacial tension but also\ncontrols the storage capacity of ions in the ionic double layers adjacent to\neach side of the interface. However, adjusting this interfacial charge by\nstatic external electric fields is difficult since the external electric fields\nare readily screened by ionic double layers that form in the vicinity of the\nexternal electrodes. This leaves the liquid-liquid interface, which is at a\nmacroscopic distance from the electrodes, unaffected. In this study we show\ntheoretically, in agreement with recent experiments, that control over this\nsurface charge at the liquid-liquid interface is nonetheless possible for\nmacroscopically large but finite closed systems in equilibrium, even when the\ndistance between the electrode and interface is orders of magnitude larger than\nthe Debye screening lengths of the two liquids. We identify a crossover\nsystem-size below which the interface and the electrodes are effectively\ncoupled. Our calculations of the interfacial tension for various electrode\npotentials are in good agreement with recent experimental data."
    },
    {
        "anchor": "Simple Model of Shape Evolution of Desiccated Colloidal Sessile Drop: We propose simple model of colloidal sessile drop desiccation. The model\ndescribes correctly both evolution of the phase boundary between sol and gel\ninside such a drop and the final shape of the dried film (deposit). The model\nis based on mass conservation and natural assumption that deposit (gel phase)\nprevents flows and evaporation.",
        "positive": "Temperature-pressure scaling for air-fluidized grains on approaches to\n  Point J: We present experiments on a monolayer of air-fluidized beads in which a\njamming transition is approached by increasing pressure, increasing packing\nfraction, and decreasing kinetic energy. This is accomplished, along with a\nnoninvasive measurement of pressure, by tilting the system and examining\nbehavior vs depth. We construct an equation of state and analyze relaxation\ntime vs effective temperature. By making time and effective temperature\ndimensionless using factors of pressure, bead size, and bead mass, we obtain a\ngood collapse of the data but to a functional form that differs from that of\nthermal hard-sphere systems. The relaxation time appears to diverge only as the\neffective temperature to pressure ratio goes to zero."
    },
    {
        "anchor": "Flexoelectric fluid membranes in electric field. Shape equations and\n  exact solutions: The shape equation for an axisymmetric fluid membrane is derived, assuming\naction of an uniform external electric field. The flexoelectric contribution to\nthe free energy of the membrane, stemming from the latter is accounted within\nthe theory by Steigmann and Agrawal. Additionally, we have introduced, in the\naforementioned functional, another term associated with a curvature induced\nmembrane polarization, as the latter was first hypothesized by A. Petrov. Some\nexact Naito-type solutions of the studied equation are given, with the free\nparameters linked to the model ones.",
        "positive": "Crack Formation in the Presence of an Electric Field in Droplets of\n  Laponite Gel: When a colloidal gel dries through evaporation, cracks are usually formed,\nwhich often reveal underlying processes at work during desiccation. Desiccating\ncolloid droplets of few hundred $\\mu l$ size show interesting effects of\npattern formation and cracking which makes this an active subject of current\nresearch. Since aqueous gels of clay are known to be strongly affected by an\nelectric field, one may expect crack patterns to exhibit a field effect. In the\npresent study we allow droplets of laponite gel to dry under a radial electric\nfield. This gives rise to highly reproducible patterns of cracks, which depend\non the strength, direction and time of exposure to the electric field. For a\ncontinuously applied DC voltage, cracks always appear on dissipation of a\ncertain constant amount of energy. If the field is switched off before cracks\nappear, the observed results are shown to obey a number of empirical scaling\nrelations, which enable us to predict the time of appearance and the number of\ncracks under specified conditions."
    },
    {
        "anchor": "Modeling Solution Drying by Moving a Liquid-Vapor Interface: Method and\n  Applications: A method of simulating the drying process of a soft matter solution with an\nimplicit solvent model by moving the liquid-vapor interface is applied to\nvarious solution films and droplets. For a solution of a polymer and\nnanoparticles, we observe \"polymer-on-top\" stratification, similar to that\nfound previously with an explicit solvent model. Furthermore, \"polymer-on-top\"\nis found even when the nanoparticle size is smaller than the radius of gyration\nof the polymer chains. For a suspension droplet of a bidisperse mixture of\nnanoparticles, we show that core-shell clusters of nanoparticles can be\nobtained via the \"small-on-outside\" stratification mechanism at fast\nevaporation rates. \"Large-on-outside\" stratification and uniform particle\ndistribution are also observed when the evaporation rate is reduced. Polymeric\nparticles with various morphologies, including Janus spheres, core-shell\nparticles, and patchy particles, are produced from drying droplets of polymer\nsolutions by combining fast evaporation with a controlled interaction between\nthe polymers and the liquid-vapor interface. Our results validate the\napplicability of the moving interface method to a wide range of drying systems.\nThe limitations of the method are pointed out and cautions are provided to\npotential practitioners on cases where the method might fail.",
        "positive": "Phase Behavior in Thin Films of Confined Colloid-Polymer Mixtures: Using self-consistent field and density-functional theories, we first\ninvestigate colloidal self-assembling of colloid/polymer films confined between\ntwo soft surfaces grafted by polymers. With the increase of colloidal\nconcentrations, the film undergoes a series of transitions from disordered\nliquid $\\to$ sparse square $\\to$ hexagonal (or mixed square-hexagonal) $\\to$\ndense square $\\to$ cylindric structures in plane, which results from the\ncompetition between the entropic elasticity of polymer brushes and the steric\npacking effect of colloidal particles. A phase diagram displays the stable\nregions of different in-layer ordering structures as the colloidal\nconcentration is varied and layering transitions as the polymer-grafted density\nis decreased. Our results show a new control mechanism to stabilize the\nordering of structures within the films."
    },
    {
        "anchor": "Local yield stress statistics in model amorphous solids: We develop and extend a method presented in [S. Patinet, D. Vandembroucq, and\nM. L. Falk, Phys. Rev. Lett., 117, 045501 (2016)] to compute the local yield\nstresses at the atomic scale in model two-dimensional Lennard-Jones glasses\nproduced via differing quench protocols. This technique allows us to sample the\nplastic rearrangements in a non-perturbative manner for different loading\ndirections on a well-controlled length scale. Plastic activity upon shearing\ncorrelates strongly with the locations of low yield stresses in the quenched\nstates. This correlation is higher in more structurally relaxed systems. The\ndistribution of local yield stresses is also shown to strongly depend on the\nquench protocol: the more relaxed the glass, the higher the local plastic\nthresholds. Analysis of the magnitude of local plastic relaxations reveals that\nstress drops follow exponential distributions, justifying the hypothesis of an\naverage characteristic amplitude often conjectured in mesoscopic or continuum\nmodels. The amplitude of the local plastic rearrangements increases on average\nwith the yield stress, regardless of the system preparation. The local yield\nstress varies with the shear orientation tested and strongly correlates with\nthe plastic rearrangement locations when the system is sheared correspondingly.\nIt is thus argued that plastic rearrangements are the consequence of shear\ntransformation zones encoded in the glass structure that possess weak slip\nplanes along different orientations. Finally, we justify the length scale\nemployed in this work and extract the yield threshold statistics as a function\nof the size of the probing zones. This method makes it possible to derive\nphysically grounded models of plasticity for amorphous materials by directly\nrevealing the relevant details of the shear transformation zones that mediate\nthis process.",
        "positive": "Tunable frequency band-gap and pulse propagation in a strongly nonlinear\n  diatomic chain: One-dimensional nonlinear phononic crystals have been assembled from periodic\ndiatomic chains of stainless steel cylinders alternated with\nPolytetrafluoroethylene (PTFE) spheres. We report the presence of acoustic band\ngaps in the dispersion relation of the linearized systems and study the\ntransformation of single and multiple pulses in linear, nonlinear and strongly\nnonlinear regimes with numerical calculations and experiments. The limiting\nfrequencies of the band gap are within the audible frequency range (20-20,000\nHz) and can be tuned by varying the particle's material properties, mass and\ninitial compression. Pulses rapidly transform within very short distances from\nthe impacted end due to the influence of the band gap in the linear and in\nnonlinear elastic chains. The effects of an in situ band gap created by a mean\ndynamic compression are observed in the strongly nonlinear wave regime."
    },
    {
        "anchor": "Confinement and collective escape of active particles: Active matter broadly covers the dynamics of self-propelled particles. While\nthe onset of collective behavior in homogenous active systems is relatively\nwell understood, the effect of inhomogeneities such as obstacles and traps\nlacks overall clarity. Here, we study how interacting self-propelled particles\nbecome trapped and released from a trap. We have found that captured particles\naggregate into an orbiting condensate with a crystalline structure. As more\nparticles are added, the trapped condensate escape as a whole. Our results shed\nlight on the effects of confinement and quenched disorder in active matter.",
        "positive": "Efficiency of isothermal active matter engines: Strong driving beats\n  weak driving: We study microscopic engines that use a single active particle as their\n\"working medium\". Part of the energy required to drive the directed motion of\nthe particle can be recovered as work, even at constant temperature. A wide\nclass of synthetic active particles can be captured by schematically accounting\nfor the chemical degrees of freedom that power the directed motion without\nhaving to resolve the exact microscopic mechanism. We derive analytical results\nfor the quasi-static thermodynamic efficiency, i.e., the fraction of available\nchemical energy that can be recovered as mechanical work. While this efficiency\nis vanishingly small for colloidal particles, it increases as the dissipation\nis increased beyond the linear response regime and goes through a maximum at\nlarge propulsion speeds. Our results demonstrate that driving beyond the linear\nresponse regime has non-trivial consequences for the efficiency of active\nengines."
    },
    {
        "anchor": "Energy Spectrum of Superfluid Turbulence without Normal Fluid: The energy spectrum of the superfluid turbulence without the normal fluid is\nstudied numerically under the vortex filament model. Time evolution of the\nTaylor-Green vortex is calculated under the full nonlocal Biot-Savart law. It\nis shown that for k<2pi/l, the energy spectrum is very similar to the\nKolmogorov's -5/3 law which is the most important statistical property of the\nconventional turbulence, where k is the wave number of the Fourier component of\nthe velocity field and 1 the average intervortex spacing. The vortex length\ndistribution becomes to obey a scaling property reflecting the self-similarity\nof the tangle.",
        "positive": "Breakdown of Nonlinear Elasticity in Amorphous Solids at Finite\n  Temperatures: It is known by now that amorphous solids at zero temperature do not possess a\nnonlinear elasticity theory: besides the shear modulus which exists, all the\nhigher order coefficients do not exist in the thermodynamic limit. Here we show\nthat the same phenomenon persists up to temperatures comparable to the glass\ntransition. The zero temperature mechanism due to the prevalence of dangerous\nplastic modes of the Hessian matrix is replaced by anomalous stress\nfluctuations that lead to the divergence of the variances of the higher order\nelastic coefficients. The conclusion is that in amorphous solids elasticity can\nnever be decoupled from plasticity: the nonlinear response is very\nsubstantially plastic."
    },
    {
        "anchor": "Steady-state distributions of ideal active Brownian particles under\n  confinement and forcing: We develop a formally exact technique for obtaining steady-state\ndistributions of non-interacting active Brownian particles in a variety of\nsystems. Our technique draws on results from the theory of two-way diffusion\nequations to solve the steady-state Smoluchowski equation for the 1-particle\ndistribution function. The methods are employed to study in detail three\nscenarios: 1) confinement in a channel, 2) a constant flux steady state, and 3)\nsedimentation in a uniform external field. In each scenario, known behaviors\nare reproduced and precisely quantified, and new results are presented. In\nparticular, in the constant flux state we derive an effective diffusivity which\ninterpolates between the ballistic behavior of particle trajectories at short\ndistances and their diffusive behavior at large distances. We also calculate\nthe sedimentation profile of active Brownian particles near a wall, which\ncomplements earlier studies on the part far from the wall. Our techniques\neasily generalize to other active models, including systems whose activity is\nmodeled in terms of Gaussian colored noise.",
        "positive": "Membrane pinning on a disordered substrate: We investigate interactions between an elastic membrane and a substrate\ncharacterized by quenched positional disorder in the height function. We show\nthat the positional disorder transforms the standard secondary DLVO minimum\ninto two separate states: the hovering state characterized by a planar membrane\nat a finite separation from the interface and a pinned state where the membrane\nfollows closely the asperities of the substrate and is as a consequence quite\ncorrugated. The transition between the two states is continuous and depends on\nthe parameters of the underlying DLVO potential as well as the parameters\ndescribing the quenched height-height correlation function of the substrate."
    },
    {
        "anchor": "Distribution of the distance between opposite nodes of random polygons\n  with a fixed knot: We examine numerically the distribution function $f_K(r)$ of distance $r$\nbetween opposite polygonal nodes for random polygons of $N$ nodes with a fixed\nknot type $K$. Here we consider three knots such as $\\emptyset$, $3_1$ and $3_1\n\\sharp 3_1$. In a wide range of $r$, the shape of $f_K(r)$ is well fitted by\nthe scaling form of self-avoiding walks. The fit yields the Gaussian exponents\n$\\nu_K = {1 \\over 2}$ and $\\gamma_K = 1$.\n  Furthermore, if we re-scale the intersegment distance $r$ by the average size\n$R_K$ of random polygons of knot $K$, the distribution function of the variable\n$r/R_K$ should become the same Gaussian distribution for any large value of $N$\nand any knot $K$. We also introduce a fitting formula to the distribution\n$g_K(R)$ of gyration radius $R$ for random polygons under some topological\nconstraint $K$.",
        "positive": "Rheo-acoustic gels: Tuning mechanical and flow properties of colloidal\n  gels with ultrasonic vibrations: Colloidal gels, where nanoscale particles aggregate into an elastic yet\nfragile network, are at the heart of materials that combine specific optical,\nelectrical and mechanical properties. Tailoring the viscoelastic features of\ncolloidal gels in real-time thanks to an external stimulus currently appears as\na major challenge in the design of \"smart\" soft materials. Here we introduce\n\"rheo-acoustic\" gels, a class of materials that are sensitive to ultrasonic\nvibrations. By using a combination of rheological and structural\ncharacterization, we evidence and quantify a strong softening in three widely\ndifferent colloidal gels submitted to ultrasonic vibrations (with submicron\namplitude and frequency 20-500 kHz). This softening is attributed to\nmicron-sized cracks within the gel network that may or may not fully heal once\nvibrations are turned off depending on the acoustic intensity. Ultrasonic\nvibrations are further shown to dramatically decrease the gel yield stress and\naccelerate shear-induced fluidization. Ultrasound-assisted fluidization\ndynamics appear to be governed by an effective temperature that depends on the\nacoustic intensity. Our work opens the way to a full control of elastic and\nflow properties by ultrasonic vibrations as well as to future theoretical and\nnumerical modeling of such rheo-acoustic gels."
    },
    {
        "anchor": "Emergence of complex behavior in gelling systems starting from simple\n  behavior of single clusters: A theoretical and numerically study of dynamical properties in the sol-gel\ntransition is presented. In particular, the complex phenomenology observed\nexperimentally and numerically in gelling systems is reproduced in the\nframework of percolation theory, under simple assumptions on the relaxation of\nsingle clusters. By neglecting the correlation between particles belonging to\ndifferent clusters, the quantities of interest (such as the self intermediate\nscattering function, the dynamical susceptibility, the Van-Hove function, and\nthe non-Gaussian parameter) are written as superposition of those due to single\nclusters. Connection between these behaviors and the critical exponents of\npercolation are given. The theoretical predictions are checked in a model for\npermanent gels, where bonds between monomers are described by a finitely\nextendable nonlinear elastic potential. The data obtained in the numerical\nsimulations are in good agreement with the analytical predictions.",
        "positive": "Defect-driven shape instabilities of bundles: Topological defects are crucial to the thermodynamics and structure of\ncondensed matter systems. For instance, when incorporated into crystalline\nmembranes like graphene, disclinations with positive and negative topological\ncharge elastically buckle the material into conical and saddle-like shapes\nrespectively. A recently uncovered mapping between the inter-element spacing in\n2D columnar structures and the metric properties of curved surfaces motivates\nbasic questions about the interplay between defects in the cross section of a\ncolumnar bundle and its 3D shape. Such questions are critical to the structure\nof a broad class of filamentous materials, from biological assemblies like\nprotein fibers to nano- or micro-structured synthetic materials like carbon\nnanotube bundles. Here, we explore the buckling behavior for elementary\ndisclinations in hexagonal bundles using a combination of continuum elasticity\ntheory and numerical simulations of discrete-filaments. We show that shape\ninstabilities are controlled by a single material-dependent parameter that\ncharacterizes the ratio of inter-filament to intra-filament elastic energies.\nAlong with a host of previously unknown shape equilibria---the filamentous\nanalogs to the conical and saddle-like shapes of defective membranes---we find\na profoundly asymmetric response to positive and negative topologically charged\ndefects in the infinite length limit that is without parallel to the membrane\nanalog. The highly non-linear dependence on the sign of the disclination charge\nis shown to have a purely geometric origin, stemming the from the distinct\ncompatibility (or incompatibility) of effectively positive- (or negative-)\ncurvature geometries with lengthwise-constant filament spacing."
    },
    {
        "anchor": "Anomalous selective reflection in cholesteryl oleyl carbonate - nematic\n  5CB mixtures and effects of their doping by single-walled carbon nanotubes: Liquid crystalline (LC) mixtures of cholesteryl oleyl carbonate (COC) and\n4-pentyl-4'-cyanobiphenyl (5CB), as well as dispersions of single-walled carbon\nnanotubes (NTs) in these mixtures, were studied by means of selective\nreflection measurements, differential scanning calorimetry (DSC) and optical\nmicroscopy. The relative mass of COC in a mixture X was varied between 0.4 and\n1.0, the temperature range of measurements was between 284 K and 314 K, and\nconcentration of NTs was fixed at 0.1 %. Two important anomalies were noted:\n(1) the cholesteric to smectic-A transition temperature increased on dilution\nof COC by non-smectogenic 5CB in the concentration range 0.8<X<1, and (2) the\nreciprocal pitch vs. 5CB concentration dependence was essentially linear, in\ncontrast to behaviour commonly observed in nematic-cholesteric mixtures. A\nmodel of molecular arrangement in the mixtures, accounting for the possibility\nof integration of 5CB dimers and monomers between COC molecules and presumably\nexplaining the experimental data, was proposed. The helical pitch of the\ncholesteric mixtures remained practically unchanged upon doping by NTs, and\nonly slight widening of the selective reflection peaks was noted. The obtained\nresults allow considering the COC+5CB mixtures as promising matrices for\ncomposite materials on the basis of liquid crystals and carbon nanotubes.",
        "positive": "Dragging a polymer chain into a nanotube and subsequent release: We present a scaling theory and Monte Carlo (MC) simulation results for a\nflexible polymer chain slowly dragged by one end into a nanotube. We also\ndescribe the situation when the completely confined chain is released and\ngradually leaves the tube. MC simulations were performed for a self-avoiding\nlattice model with a biased chain growth algorithm, the pruned-enriched\nRosenbluth method. The nanotube is a long channel opened at one end and its\ndiameter $D$ is much smaller than the size of the polymer coil in solution. We\nanalyze the following characteristics as functions of the chain end position\n$x$ inside the tube: the free energy of confinement, the average end-to-end\ndistance, the average number of imprisoned monomers, and the average stretching\nof the confined part of the chain for various values of $D$ and for the number\nof monomers in the chain, $N$. We show that when the chain end is dragged by a\ncertain critical distance $x^*$ into the tube, the polymer undergoes a\nfirst-order phase transition whereby the remaining free tail is abruptly sucked\ninto the tube. This is accompanied by jumps in the average size, the number of\nimprisoned segments, and in the average stretching parameter. The critical\ndistance scales as $x^*\\sim ND^{1-1/\\nu}$. The transition takes place when\napproximately 3/4 of the chain units are dragged into the tube. The theory\npresented is based on constructing the Landau free energy as a function of an\norder parameter that provides a complete description of equilibrium and\nmetastable states. We argue that if the trapped chain is released with all\nmonomers allowed to fluctuate, the reverse process in which the chain leaves\nthe confinement occurs smoothly without any jumps. Finally, we apply the theory\nto estimate the lifetime of confined DNA in metastable states in nanotubes."
    },
    {
        "anchor": "The development of food protein-inorganic hybrid nanoflowers with\n  outstanding role in stabilizing natural pigments: Protein-inorganic hybrid nanoflowers (HNFs) possess unique properties in\npromoting surface reaction and have attracted wide-spread attention as a newly\ndeveloped nanomaterial. However, the availability of protein sources has up to\nnow been mostly limited to enzymes, which narrows the application of HNFs\nespecially in food industry. Here we show that for many types of food protein,\nenzymatic hydrolysis can improve its ability to form versatile HNFs, or even\ninduce HNF formation where the protein source did not show its formation a\npriori. The treatment of enzymatic hydrolysis increases the flexibility of such\nproteins and induces nucleation sites of HNFs in the early formation stage by\ndecomposing those proteins into polypeptides. In particular, the HNF prepared\nwith soy protein hydrolysate further shows a high loading capacity of\nwater-soluble Monascus red, reaching up to 554.1 mg per gram of HNF. Its\nstabilization towards lipophilic curcumin is similarly impressive with the\nloading capacity reaching 21.9 mg per gram of HNF. This HNF could also\neffectively protect these two sensitive natural pigments in harsh environments.\nThis research significantly broadens the available protein source for HNF\nfabrication and demonstrates the potential of HNFs as novel protein-based\ndelivery systems - especially for sensitive natural pigments - which could\nserve the fields of food, cosmetic and medicine.",
        "positive": "Experimental evidence of non-Amontons behaviour at a multicontact\n  interface: We report on normal stress field measurements at the multicontact interface\nbetween a rough elastomeric film and a smooth glass sphere under normal load,\nusing an original MEMS-based stress sensing device. These measurements are\ncompared to Finite Elements Method calculations with boundary conditions\nobeying locally Amontons' rigid-plastic-like friction law with a uniform\nfriction coefficient. In dry contact conditions, significant deviations are\nobserved which decrease with increasing load. In lubricated conditions, the\nmeasured profile recovers almost perfectly the predicted profile. These results\nare interpreted as a consequence of the finite compliance of the multicontact\ninterface, a mechanism which is not taken into account in Amontons' law."
    },
    {
        "anchor": "Effect of the Berendsen thermostat on dynamical properties of water: The effect of the Berendsen thermostat on the dynamical properties of bulk\nSPC/E water is tested by generating power spectra associated with fluctuations\nin various observables. The Berendsen thermostat is found to be very effective\nin preserving temporal correlations in fluctuations of tagged particle\nquantities over a very wide range of frequencies. Even correlations in\nfluctuations of global properties, such as the total potential energy, are\nwell-preserved for time periods shorter than the thermostat time constant.\nDeviations in dynamical behaviour from the microcanonical limit do not,\nhowever, always decrease smoothly with increasing values of the thermostat time\nconstant but may be somewhat larger for some intermediate values of $\\tau_B$,\nspecially in the supercooled regime, which are similar to time scales for slow\nrelaxation processes in bulk water.",
        "positive": "Buckling initiation in layered hydrogels during transient swelling: Subjected to compressive stresses, soft polymers with stiffness gradients can\ndisplay various buckling patterns. These compressive stresses can have\ndifferent origins, like mechanical forces, temperature changes, or, for\nhydrogel materials, osmotic swelling. Here, we focus on the influence of the\ntransient nature of osmotic swelling on the initiation of buckling in confined\nlayered hydrogel structures. A constitutive model for transient hydrogel\nswelling is outlined and implemented as a user-subroutine for the commercial\nfinite element software Abaqus. The finite element procedure is benchmarked\nagainst linear perturbation analysis results for equilibrium swelling showing\nexcellent correspondence. Based on the finite element results we conclude that\nthe initiation of buckling in a two-layered hydrogel structure is highly\naffected by transient swelling effects, with instability emerging at lower\nswelling ratios and later in time with a lower diffusion coefficient. In\naddition, for hard-on-soft systems the wavelength of the buckling pattern is\nfound to decrease as the diffusivity of the material is reduced for gels with a\nrelatively low stiffness gradient between the substrate and the upper film.\nThis study highlights the difference between equilibrium and transient swelling\nwhen it comes to the onset of instability in hydrogels, which is believed to be\nof importance as a fundamental aspect of swelling as well as providing input to\nguiding principles in the design of specific hydrogel systems."
    },
    {
        "anchor": "Confined packings of frictionless spheres and polyhedra: By means of numerical simulations, we study the influence of confinement on\nthree-dimensional random close packed (RCP) granular materials subject to\ngravity. The effects of grain shape (spherical or polyhedral) and\npolydispersity on this dependence are investigated. In agreement with a simple\ngeometrical model, the solid fraction is found to decrease linearly for\nincreasing confinement no matter the grain shape. This decrease remains valid\nfor bidisperse sphere packings although the gradient seems to reduce\nsignificantly when the proportion of small particles reaches 40% by volume. The\naforementioned model is extended to capture the effect of the confinement on\nthe coordination number.",
        "positive": "Tube Model for the Elasticity of Entangled Nematic Rubbers: Dense rubbery networks are highly entangled polymer systems, with significant\ntopological restrictions for the mobility of neighbouring chains and crosslinks\npreventing the reptation constraint release. In a mean field approach,\nentanglements are treated within the famous reptation approach, since they\neffectively confine each individual chain in a tube-like geometry. We apply the\nclassical ideas of reptation dynamics to calculate the effective rubber-elastic\nfree energy of anisotropic networks, nematic liquid crystal elastomers, and\npresent the first theory of entanglements for such a material."
    },
    {
        "anchor": "Self-Driven Configurational Dynamics in Frustrated Spring-Mass Systems: Various physical systems relax mechanical frustration through configurational\nrearrangements. We examine such rearrangements via Hamiltonian dynamics of\nsimple internally-stressed harmonic 4-mass systems. We demonstrate\ntheoretically and numerically how mechanical frustration controls the\nunderlying potential energy landscape. Then, we examine the harmonic 4-mass\nsystems' Hamiltonian dynamics and relate the onset of chaotic motion to\nself-driven rearrangements. We show such configurational dynamics may occur\nwithout strong precursors, rendering such dynamics seemingly spontaneous.",
        "positive": "Macroscopic quantum tunneling and resonances in coupled Bose-Einstein\n  condensates with oscillating atomic scattering length: We study the macroscopic quantum tunneling, self-trapping phenomena in two\nweakly coupled Bose-Einstein condensates with periodically time-varying atomic\nscattering length.\n  The resonances in the oscillations of the atomic populations are\ninvestigated. We consider oscillations in the cases of macroscopic quantum\ntunneling and the self-trapping regimes. The existence of chaotic oscillations\nin the relative atomic population due to overlaps between nonlinear resonances\nis showed. We derive the whisker-type map for the problem and obtain the\nestimate for the critical amplitude of modulations leading to chaos. The\ndiffusion coefficient for motion in the stochastic layer near separatrix is\ncalculated. The analysis of the oscillations in the rapidly varying case shows\nthe possibilty of stabilization of the unstable Pi-mode regime."
    },
    {
        "anchor": "Kinetics of symmetry and asymmetry in a phase-separating bilayer\n  membrane: We simulate a phase-separating a bilayer in which the leaflets experience a\ndirect coupling favouring local compositional symmetry (\"registered\" bilayer\nphases), and an indirect coupling due to hydrophobic mismatch that favours\nstrong local asymmetry (\"antiregistered\" bilayer phases). For wide ranges of\noverall leaflet compositions, multiple competing states are possible. For\nestimated physical parameters, a quenched bilayer may first evolve toward a\nmetastable state more asymmetric than if the leaflets were uncorrelated;\\\nsubsequently, it must nucleate to reach its equilibrium, more symmetric, state.\nThese phase-transition kinetics exhibit characteristic signatures through which\nfundamental and opposing inter-leaflet interactions may be probed. We emphasise\nhow bilayer phase diagrams with a separate axis for each leaflet can account\nfor overall and local symmetry/asymmetry, and capture a range of observations\nin the experiment and simulation literature.",
        "positive": "Liquid-Liquid Critical Point in Phosphorus: The study of liquid-liquid phase transition has attracted considerable\nattention. One interesting example of such phenomenon is phosphorus for which\nthe existence a first-order phase transition between a low density insulating\nmolecular phase and a conducting polymeric phase has been experimentally\nestablished. In this paper, we model this transition by an ab-initio quality\nmolecular dynamics simulation and explore a large portion of the liquid section\nof the phase diagram. We draw the liquid-liquid coexistence curve and determine\nthat it terminates into a second-order critical point. Close to the critical\npoint, large coupled structure and electronic structure fluctuations are\nobserved."
    },
    {
        "anchor": "Electron channels in biomolecular nanowires: We report a first-principle study of the electronic and conduction properties\nof a quadruple-helix guanine wire (G4-wire), a DNA-derivative, with inner\npotassium ions. The analysis of the electronic structure highlights the\npresence of energy manifolds that are equivalent to the bands of\n(semi)conducting materials, and reveals the formation of extended electron\nchannels available for charge transport along the wire. The specific\nmetal-nucleobase interactions affect the electronic properties at the Fermi\nlevel, leading the wire to behave as an intrinsically p-doped system.",
        "positive": "Topology of Roscoe's- and Hvorslev's- Surfaces in the Phase Space of\n  Soil Mechanics: In general, the evolution of soil submitted to simple stress-strain paths is\ncharacterized using the 3d phase space (v,p',q) i.e. (specific volume, mean\nintergranular pressure, deviatoric stress); one finds that all trajectories end\nup at a line of attracting point called the critical-state line. The surface of\nRoscoe (Hvorslev) is defined as the surface made of the last part of the set of\ntrajectories ending to a given critical point and coming from all states of\nnormally consolidated soils (from all states of over consolidated soils). It is\ndemonstrated that these two sets are part of the same surface, which is\nconfirmed by experimental data."
    },
    {
        "anchor": "Polarization effects on the dielectric properties of molten AgI: The results are reported of molecular dynamics simulations of the static\nlongitudinal dielectric and response functions for molten AgI at 923 K using\ntwo ionic models. The first one is a rigid ion model, while in the second the\ninduced dipole moments of the anions are added to the effective pair potentials\nof the first. It is derived theoretically that the dielectric functions for the\npolarizable ion model are determined by spatial correlations of charge and\ndipole moment densities. The charge structure factor at long wavelengths is\nalso studied.",
        "positive": "A polymer-tethered particle confined in a slit: Shape transformations of hairy nanoparticles under confinement are studied\nusing molecular dynamic simulations. We discuss the behavior of these particles\nin slits with inert or attractive walls. We assume that only chain-wall\ninteractions are attractive. The impact of the strength of interactions with\nthe walls and the width of the slits on the particle configuration is shown. In\nthe case of attractive surfaces, we found new structures in which the chains\nare connected with both walls and form bridges between them: pillars,\nsymmetrical and asymmetrical spools, and hourglasses. In wide pores with\nstrongly attractive walls, hairy particles adsorb on one of the surfaces and\nform \"mounds\" or starfish-like strucures."
    },
    {
        "anchor": "Ripples and Grains Segregation on Unpaved Road: Ripples or corrugations are common phenomena observed in unpaved roads in\nless developed countries or regions. They cause several damages in vehicles\nleading to increased maintenance and product costs. In this paper, we present a\ncomputational study about the so-called washboard roads. Also, we study grain\nsegregation on unpaved roads. Our simulations have been performed by the\nDiscrete Element Method (DEM). In our model, the grains are regarded as soft\ndisks. The grains are subjected to a gravitational field and both translational\nand rotational movements are allowed. The results show that wheels' of\ndifferent sizes, weights and moving with different velocities can change\ncorrugations amplitude and wavelength. Our results also show that some\nwavelength values are related to specific wheels' speed intervals. Segregation\nhas been studied in roads formed by three distinct grain diameters\ndistribution. We observed that the phenomenon is more evident for higher grain\nsize dispersion.",
        "positive": "Clustering instability of focused swimmers: One of the hallmarks of active matter is its rich nonlinear dynamics and\ninstabilities. Recent numerical simulations of phototactic algae showed that a\nthin jet of swimmers, obtained from hydrodynamic focusing inside a Poiseuille\nflow, was unstable to longitudinal perturbations with swimmers dynamically\nclustering (Jibuti et al., Phys. Rev. E, 90, 2014). As a simple starting point\nto understand these instabilities, we consider in this paper an initially\nhomogeneous one-dimensional line of aligned swimmers moving along the same\ndirection, and characterise its instability using both a continuum framework\nand a discrete approach. In both cases, we show that hydrodynamic interactions\nbetween the swimmers lead to instabilities in density for which we compute the\ngrowth rate analytically. Lines of pusher-type swimmers are predicted to remain\nstable while lines of pullers (such as flagellated algae) are predicted to\nalways be unstable."
    },
    {
        "anchor": "Aging phenomena in PMMA thin films -- memory and rejuvenation effects: Aging dynamics in thin films of poly(methyl methacrylate) (PMMA) have been\ninvestigated through dielectric measurements for different types of aging\nprocesses. The dielectric constant was found to decrease with increasing aging\ntime at an aging temperature in many cases. An increase in the dielectric\nconstant was also observed in the long time region ($\\ge$11h) near the glass\ntransition temperature for thin films with thickness less than 26nm. In the\nconstant rate mode including a temporary stop at a temperature $T_a$, the\nmemory of the aging at $T_a$ was found to be kept and then to be recalled\nduring the subsequent heating process. In the negative temperature cycling\nprocess, a strong rejuvenation effect has been observed after the temperature\nshift from the initial temperature $T_1$ to the second temperature\n$T_2$($=T_1+\\Delta T$) when $\\Delta T\\approx -20$K. Furthermore, a full memory\neffect has also been observed for the temperature shift from $T_2$ to $T_1$.\nThis suggests that the aging at $T_1$ is totally independent of that at $T_2$\nfor $\\Delta T\\approx -20$K. As $|\\Delta T|$ decreases, the independence of the\naging between the two temperatures was found to be weaken, $i.e.,$ the\neffective time, which is a measure of the contribution of the aging at $T_1$ to\nthat at $T_2$, is a decreasing function of $|\\Delta T|$ in the negative region\nof $\\Delta T$. As the film thickness decreases from 514nm to 26nm, the $|\\Delta\nT|$ dependence of the effective time was found to become much stronger. The\ncontribution of the aging at $T_2$ to that at $T_1$ disappears more rapidly\nwith increasing $|\\Delta T|$ in thin film geometry than in the bulk state.",
        "positive": "Volume conservation during finite plastic deformation: An elastoplastic theory is not volume conserved if it improperly sets an\narbitrary plastic strain rate tensor to be deviatoric. This paper discusses how\nto rigorously realize volume conservation in finite strain regime, especially\nwhen the unloading stress free configuration is not adopted or unique in the\nelastoplastic theories. An accurate condition of volume conservation is\nclarified and used in this paper that the density of a volume element after the\napplied loads are completely removed should be identical to that of the initial\nstress free states. For the elastoplastic theories that adopt the unloading\nstress free configuration (i.e. the intermediate configuration), the accurate\ncondition of volume conservation is satisfied only if specific definitions of\nthe plastic strain rate are used among many other different definitions. For\nthe elastoplastic theories that do not adopt the unloading stress free\nconfiguration, it is even more difficult to realize volume conservation as the\ninformation of the stress free state lacks. To find a universal approach of\nrealizing volume conservation for elastoplastic theories whether or not adopt\nthe unloading stress free configuration, we propose a single assumption that\nthe density of material only depends on the trace of the Cauchy stress, and\ninterestingly find that the zero trace of the plastic stress rate is equivalent\nto the accurate condition of volume conservation. Two strategies are further\nproposed to satisfy the accurate condition of volume conservation: directly and\nslightly revising the tangential stiffness tensor or using a properly chosen\nstress/strain measure and elastic compliance tensor. They are implemented into\nexisting elastoplastic theories, and the volume conservation is demonstrated by\nboth theoretical proof and numerical examples."
    },
    {
        "anchor": "What is wrong with the image charge force of keV ions in insulating\n  nano-capillaries: In nano-capillaries of large aspect ratio, the attractive image charge force\nis strong enough to affect the trajectory of ions passing through capillaries\nand consequently to diminish the fraction of transmitted beam ions. We\ncalculated the theoretically transmitted fraction, using an approached but\nCPU-friendly expression of the image charge force valid in the case of a static\nion and an infinite cylindrical dielectric interface. When comparing the\ntheoretically transmitted fraction to available experimental data for\nnano-capillaries with an inner diameter of less than 200 nm, we found a\nsurprisingly large disagreement, i.e., the theoretically transmitted fractions\nwere easily an order of magnitude lower than the experimental ones. Noting that\nthe image charge force depends on the velocity of the ion via the frequency\ndependent relative permittivity of the insulator, we investigated whether the\ndisagreement could be lifted using a velocity depend image charge force. We\ngive the exact expressions of the dynamical image charge force for a plane and\ncylindrical dielectric interface as a function of the ion velocity. We then\nre-evaluated the theoretically transmitted fractions in the case of SiO$_2$ and\nPET dielectric interfaces. Our findings are discussed in the light of the\navailable experimental data.",
        "positive": "Secondary Structures in Long Compact Polymers: Compact polymers are self-avoiding random walks which visit every site on a\nlattice. This polymer model is used widely for studying statistical problems\ninspired by protein folding. One difficulty with using compact polymers to\nperform numerical calculations is generating a sufficiently large number of\nrandomly sampled configurations. We present a Monte-Carlo algorithm which\nuniformly samples compact polymer configurations in an efficient manner\nallowing investigations of chains much longer than previously studied. Chain\nconfigurations generated by the algorithm are used to compute statistics of\nsecondary structures in compact polymers. We determine the fraction of monomers\nparticipating in secondary structures, and show that it is self averaging in\nthe long chain limit and strictly less than one. Comparison with results for\nlattice models of open polymer chains shows that compact chains are\nsignificantly more likely to form secondary structure."
    },
    {
        "anchor": "Dynamic structure factors of a dense mixture: We compute the dynamic structure factors of a dense binary liquid mixture.\nThese describe dynamics on molecular length scales, where structural relaxation\nis important. We find that the presence of a few large particles in a dense\nfluid of small particles slows down the dynamics considerably. We also observe\na deep narrowing of the spectrum for a disordered mixture composed of a nearly\nequal packing of the two species. In contrast, a few small particles diffuse\neasily in the background of a dense fluid of large particles. We expect our\nresults to describe neutron scattering from a dense mixture.",
        "positive": "Assembly of nanocube super-structures directed by surface and magnetic\n  interactions: We model the stabilization of clusters and lattices of cuboidal particles\nwith long-ranged magnetic dipolar and short-ranged surface interactions. Two\nrealistic systems were considered: one with magnetization orientated in the\n[001] crystallographic direction, and the other with magnetization along the\n[111] direction. We have studied magnetic nanocubes clusters first in the limit\nof $T=0$~K intending to elucidate the structural genesis of low energy\nconfigurations and then analyzed finite-temperature behavior of the same\nsystems in simulations. Our results demonstrate that dipolar coupling can\nstabilize nanoparticle assemblies with cubic, planar, and linear arrangements\nseen previously in experiments. While attractive surface energy supports the\nformation of super-cubes, the repulsion results in the elongated structures in\nthe form of rods and chains. We observe the stabilization of the ferromagnetic\nplanar arrangements of the cubes standing on their corners and in contact over\nedges. We illustrate that minimal energy structures depend only on the size of\nthe assembly and balance of surface repulsion and magnetic dipolar coupling.\nThe presented results are scalable to different particle sizes and material\nparameters."
    },
    {
        "anchor": "Drop dynamics on hydrophobic and superhydrophobic surfaces: We investigate the dynamics of micron-scale drops pushed across a hydrophobic\nor superhydrophobic surface. The velocity profile across the drop varies from\nquadratic to linear with increasing height, indicating a crossover from a\nsliding to a rolling motion. We identify a mesoscopic slip capillary number\nwhich depends only on the motion of the contact line and the shape of the drop,\nand show that the angular velocity of the rolling increases with increasing\nviscosity. For drops on superhydrophobic surfaces we argue that a tank treading\nadvance from post to post replaces the diffusive relaxation that allows the\ncontact line to move on smooth surfaces. Hence drops move on superhydrophobic\nsurfaces more quickly than on smooth geometries.",
        "positive": "Programming hydrogel adhesion with engineered polymer network topology: Hydrogel adhesion that can be easily modulated in magnitude, space, and time\nis desirable in many emerging applications ranging from tissue engineering, and\nsoft robotics, to wearable devices. In synthetic materials, these complex\nadhesion behaviors are often achieved individually with mechanisms and\napparatus that are difficult to integrate. Here, we report a universal strategy\nto embody multifaceted adhesion programmability in synthetic hydrogels. By\ndesigning the surface network topology of a hydrogel, supramolecular linkages\nthat result in contrasting adhesion behaviors are formed on the hydrogel\ninterface. The incorporation of different topological linkages leads to\ndynamically tunable adhesion with high-resolution spatial programmability\nwithout alteration of bulk mechanics and chemistry. Further, the association of\nlinkages enables stable and tunable adhesion kinetics that can be tailored to\nsuit different applications. We rationalize the physics of chain slippage,\nrupture, and diffusion that underpins emergent programmable behaviors. We then\nincorporate the strategy into the designs of various devices such as smart\nwound patches, fluidic channels, drug-eluting devices, and reconfigurable soft\nrobotics. Our study presents a simple and robust platform in which adhesion\ncontrollability in multiple aspects can be easily integrated into a single\ndesign of a hydrogel network."
    },
    {
        "anchor": "Quasicrystal kirigami: Kirigami, the art of introducing cuts in thin sheets to enable articulation\nand deployment, has become an inspiration for a novel class of mechanical\nmetamaterials with unusual properties. Here we complement the use of periodic\ntiling patterns for kirigami designs by showing that quasicrystals can also\nserve as the basis for designing deployable kirigami structures, and analyze\nthe geometrical, topological and mechanical properties of these aperiodic\nkirigami structures.",
        "positive": "Quenched Dynamics of Artificial Spin Ice: Coarsening versus Kibble-Zurek: Artificial spin ices are ideal frustrated model systems in which to explore\nor design emergent phenomena with unprecedented characterization of the\nconstituent degrees of freedom. In square spin ice, violations of the ice rule\nare topological excitations essential to the kinetics of the system, providing\nan ideal testbed for studying the dynamics of such defects under varied quench\nrates. In this work we describe the first test of the Kibble-Zurek mechanism\nand critical coarsening in colloidal square and colloidal hexagonal ice under\nquenches from a weakly interacting liquid state into a strongly interacting\nregime. As expected, for infinitely slow quenches, the system is defect free,\nwhile for increasing quench rate, an increasing number of defects remain in the\nsample. For square ice, we find regimes in which the defect population\ndecreases as a power law with decreasing quench rate. A detailed scaling\nanalysis shows that for a wide range of parameters, including quench rates that\nare accessible by experiments, the behavior is described by critical coarsening\nrather than by the Kibble-Zurek mechanism, since the defect-defect interactions\nare long ranged. For quenches closer to the critical point, however, there can\nbe a competition between the two mechanisms."
    },
    {
        "anchor": "Comprehensive view of microscopic interactions between DNA-coated\n  colloids: The self-assembly of DNA-coated colloids into highly-ordered structures\noffers great promise for advanced optical materials. However, control of\ndisorder, defects, melting, and crystal growth is hindered by the lack of a\nmicroscopic understanding of DNA-mediated colloidal interactions. Here we use\ntotal internal reflection microscopy to measure in situ the interaction\npotential between DNA-coated colloids with nanometer resolution and the\nmacroscopic melting behavior. The range and strength of the interaction are\nmeasured and linked to key material design parameters, including DNA sequence,\npolymer length, grafting density, and complementary fraction. We present a\nfirst-principles model that quantitatively reproduces our experimental data\nwithout fitting parameters over a wide range of DNA ligand designs. Our theory\nidentifies a subtle competition between DNA binding and steric repulsion and\naccurately predicts adhesion and melting at a molecular level. Combining\nexperimental and theoretical results, our work provides a quantitative and\npredictive approach for guiding material design with DNA-nanotechnology and can\nbe further extended to a diversity of colloidal and biological systems.",
        "positive": "Controlling Secondary Structures of Bio-Polymers with Hydrogen-Like\n  Bonding: We present results for a lattice model of bio-polymers where the type of\n$\\beta$-sheet formation can be controlled by different types of hydrogen bonds\ndepending on the relative orientation of close segments of the polymer. Tuning\nthese different interaction strengths leads to low-temperature structures with\ndifferent types of orientational order. We perform simulations of this model\nand so present the phase diagram, ascertaining the nature of the phases and the\norder of the transitions between these phases."
    },
    {
        "anchor": "Nonequilibrium Probability Currents in Optically-Driven Colloidal\n  Suspensions: In the absence of directional motion it is often hard to recognize athermal\nfluctuations. Probability currents provide such a measure in terms of the rate\nat which they enclose area in phase space. We measure this area enclosing rate\nfor trapped colloidal particles, where only one particle is driven. By\ncombining experiment, theory, and simulation, we single out the effect of the\ndifferent time scales in the system on the measured probability currents. In\nthis controlled experimental setup, particles interact hydrodynamically. These\ninteractions lead to a strong spatial dependence of the probability currents\nand to a local influence of athermal agitation. In a multiple-particle system,\nwe show that even when the driving acts only on one particle, probability\ncurrents occur between other, non-driven particles. This may have significant\nimplications for the interpretation of fluctuations in biological systems\ncontaining elastic networks in addition to a suspending fluid.",
        "positive": "Plastic flow in a sheared polycrystalline solid using phase field model: Plastic deformation in solids induced by external shear stress is of huge\npractical interest. Presence of local crystalline order in polycrystals,\nconsisting of many grains, distinguishes its deformation pattern from that of\namorphous materials. Despite strong anisotropy, induced by external stress, the\nplastic flow and the consequent deformation field show strong dynamical\nheterogeneity. The distribution $P(u)$ of particle displacements ($u$) shows\nthree distinct regimes including a power law scaling regime at moderate\ndisplacements. Using a phase field simulation we show how polycrystals generate\nsaddle and vortex like flow patterns, which hitherto have been termed as\nelementary plastic events in the context of amorphous materials. Interestingly,\nsuch events here find natural explanation in terms of the underlying\ndislocation dynamics. We also characterize the spatial distribution of the flow\nfield using Okubo-Weiss measure."
    },
    {
        "anchor": "Monte Carlo computer simulations and electron microscopy of colloidal\n  cluster formation via emulsion droplet evaporation: We consider a theoretical model for a binary mixture of colloidal particles\nand spherical emulsion droplets. The hard sphere colloids interact via\nadditional short-ranged attraction and long-ranged repulsion. The\ndroplet-colloid interaction is an attractive well at the droplet surface, which\ninduces the Pickering effect. The droplet-droplet interaction is a hard-core\ninteraction. The droplets shrink in time, which models the evaporation of the\ndispersed (oil) phase, and we use Monte Carlo simulations for the dynamics. In\nthe experiments, polystyrene particles were assembled using toluene droplets as\ntemplates. The arrangement of the particles on the surface of the droplets was\nanalyzed with cryogenic field emission scanning electron microscopy. Before\nevaporation of the oil, the particle distribution on the droplet surface was\nfound to be disordered in experiments, and the simulations reproduce this\neffect. After complete evaporation, ordered colloidal clusters are formed that\nare stable against thermal fluctuations. Both in the simulations and with field\nemission scanning electron microscopy, we find stable packings that range from\ndoublets, triplets, and tetrahedra to complex polyhedra of colloids. The\nsimulated cluster structures and size distribution agree well with the\nexperimental results. We also simulate hierarchical assembly in a mixture of\ntetrahedral clusters and droplets, and find supercluster structures with\nmorphologies that are more complex than those of clusters of single particles.",
        "positive": "Fundamental measure theory of inhomogeneous two-body correlation\n  functions: For the three-dimensional hard-sphere model we investigate the inhomogeneous\ntwo-body correlations predicted by Rosenfeld's fundamental measure theory. For\nthe special cases in which the density has either planar or spherical symmetry\nwe provide analytic formulae for the Hankel and Legendre transforms,\nrespectively, of the inhomogeneous two-body direct correlation function as\nexplicit functionals of the density. When combined with the Ornstein-Zernike\nrelation our analytical results allow for rapid calculation of inhomogeneous\nhard-sphere density correlations in real-space. These provide not only\ninformation about the packing structures of the hard-sphere system, but also\nform an essential building-block for constructing perturbation theories of more\nrealistic models."
    },
    {
        "anchor": "Reexamination of Tolman's law and the Gibbs adsorption equation for\n  curved interfaces: In manuscript arXiv:1703.08719 [cond-mat.soft], it was claimed that the\nwell-known deduction of Tolman's law is not rigorous, since Tolman's argument\nimplies that two different definitions of the surface tension, called $\\gamma$\nand $\\bar\\gamma$ in the manuscript, coincide. This claim is retracted as it can\nbe shown by free-energy minimization that $\\gamma = \\bar\\gamma$ indeed holds\nfor the Laplace radius. Joachim Gro\\ss, Philipp Rehner, Carlos Vega, \\O{}ivind\nWilhelmsen, and the anonymous reviewers of The Journal of Chemical Physics\ncontributed to finding the mistake in the manuscript.",
        "positive": "Adhesive contact of elastomers: effective adhesion energy and creep\n  function: For the adhesive contact of elastomers, we propose expressions to quantify\nthe impact of viscoelastic response on effective adhesion energy as a function\nof contact edge velocity. The expressions we propose are simple analytical\nfunctionals of the creep response and should be suitable for experimental data\nanalysis in terms of measured rheologies. We also emphasize the role of the\ncoupling between local stress field at the contact edge and the macroscopic\nremote loading (far field). We show that the contrast between growing and\nreceding contact originates from the impact of viscoelastic response on\ncoupling, while the separation process at the contact edge is similarly\naffected by viscoelasticity in both cases."
    },
    {
        "anchor": "Poroelastic toughening in polymer gels: A theoretical and numerical\n  study: We explore the Mode I fracture toughness of a polymer gel containing a\nsemi-infinite, growing crack. First, an expression is derived for the energy\nrelease rate within the linearized, small-strain setting. This expression\nreveals a crack tip velocity-independent toughening that stems from the\nporoelastic nature of polymer gels. Then, we establish a poroelastic cohesive\nzone model that allows us to describe the micromechanics of fracture in gels by\nidentifying the role of solvent pressure in promoting poroelastic toughening.\nWe evaluate the enhancement in the effective fracture toughness through\nasymptotic analysis. We confirm our theoretical findings by means of numerical\nsimulations concerning the case of a steadily propagating crack. In broad\nterms, our results explain the role of poroelasticity and of the processes\noccurring in the fracturing region in promoting toughening of polymer gels.",
        "positive": "Plateau Moduli of Several Single-Chain Slip-Link and Slip-Spring Models: We calculate the plateau moduli of several single-chain slip-link and\nslip-spring models for entangled polymers. In these models, the entanglement\neffects are phenomenologically modeled by introducing topological constraints\nsuch as slip-links and slip-springs. The average number of segments between two\nneighboring slip-links or slip-springs, $N_{0}$, is an input parameter in these\nmodels. To analyze experimental data, the characteristic number of segments in\nentangled polymers $N_{e}$ estimated from the plateau modulus is used instead.\nBoth $N_{0}$ and $N_{e}$ characterize the topological constraints in entangled\npolymers, and naively $N_{0}$ is considered to be the same as $N_{e}$. However,\nearlier studies showed that $N_{0}$ and $N_{e}$ (or the plateau modulus) should\nbe considered as independent parameters. In this work, we show that due to the\nfluctuations at the short time scale, $N_{e}$ deviates from $N_{0}$. This means\nthat the relation between $N_{0}$ and the plateau modulus is not simple as\nnaively expected. The plateau modulus (or $N_{e}$) depends on the\nsubchain-scale details of the employed model, as well as the average number of\nsegments $N_{0}$. This is due to the fact that the subchain-scale fluctuation\nmechanisms depend on the model rather strongly. We theoretically calculate the\nplateau moduli for several single-chain slip-link and slip-spring models. Our\nresults explicitly show that the relation between $N_{0}$ and $N_{e}$ is\nmodel-dependent. We compare theoretical results with various simulation data in\nthe literature, and show that our theoretical expressions reasonably explain\nthe simulation results."
    },
    {
        "anchor": "Configurational temperature in active matter. II. Quantifying the\n  deviation from thermal equilibrium: This paper suggests using the configurational temperature $\\Tc$ for\nquantifying how far an active-matter system is from thermal equilibrium. We\nmeasure this ``distance'' by the ratio of the systemic temperature $\\Ts$ to\n$\\Tc$, where $\\Ts$ is the canonical-ensemble temperature for which the average\npotential energy is equal to that of the active-matter system. $\\Tc$ is\n``local'' in the sense that it is the average of a function, which only depends\non how the potential energy varies in the vicinity of a given configuration; in\ncontrast $\\Ts$ is a global quantity. The quantity $\\Ts/\\Tc$ is straightforward\nto evaluate in a computer simulation; equilibrium simulations in conjunction\nwith a single steady-state active-matter configuration are enough to determine\n$\\Ts/\\Tc$. We validate the suggestion that $\\Ts/\\Tc$ quantifies the deviation\nfrom thermal equilibrium by data for the radial distribution function of 3d\nKob-Andersen and 2d Yukawa active-matter models with active Ornstein-Uhlenbeck\nand active Brownian Particle dynamics. Moreover, we show that $\\Ts/\\Tc$,\nstructure, and dynamics of the homogeneous phase are all approximately\ninvariant along the motility-induced phase separation (MIPS) boundary in the\nphase diagram of the 2d Yukawa model. The measure $\\Ts/\\Tc$ is not limited to\nactive matter; it can be used for quantifying how far any system involving a\npotential-energy function, e.g., a driven Hamiltonian system, is from thermal\nequilibrium.",
        "positive": "Percolation of nonequilibrium assemblies of colloidal particles in\n  active chiral liquids: The growing interest in the non-equilibrium assembly of colloidal particles\nin active liquids is driven by the motivation to create novel structures\nendowed with tunable properties unattainable within the confines of equilibrium\nsystems. Here, we present an experimental investigation of the structural\nfeatures of colloidal assemblies in active liquids of chiral E. coli. The\ncolloidal particles form dynamic clusters due to the effective interaction\nmediated by active media. The activity and chirality of the swimmers strongly\ninfluence the dynamics and local ordering of colloidal particles, resulting in\nclusters with persistent rotation, whose structure differs significantly from\nthose in equilibrium systems with attractive interactions, such as\ncolloid-polymer mixtures. The colloid-bacteria mixture displays several\nhallmark features of a percolation transition at a critical density, where the\nclusters span the system size. However, a closer examination of the critical\nexponents associated with cluster size distribution, average cluster size, and\ncorrelation length in the vicinity of the critical density suggest strong\ndeviations from the prediction of the standard continuum percolation model.\nTherefore, our experiments reveal a richer phase behavior of colloidal\nassemblies in active liquids."
    },
    {
        "anchor": "Emergence of Self-dual Patterns in Active Colloids with Periodical\n  Feedback to Local Density: The central task in the study of self-organization is to explore the general\nmechanism of emergences. However, this is inhibited by the missing of a full\nknowledge of the microscopic dynamics of emergence. Here, in this study, the\nmicroscopic dynamics of self-organization for patterns is investigated and\nquantified in a periodically propelled Quincke system. The periodical coupling\nbetween propulsion and repulsion at the particle level leads to local directed\noscillating particle flows and promises a loop of positive feedback to density\nfluctuations. Nevertheless, the global evolution of the resulting cluster phase\nis dominated by a global dual transformation. As stable attractors of the dual\ntransformation, self-dual patterns including stripe patterns and square\nlattices can be achieved by tuning the strength and the frequency of\npropelling. However, stripes are possible only at strong propelling where\nboundary particle flows can form. The findings in this study show that the\ndynamics of emergence on different length scales are controlled by different\nmechanisms. The competition and the interplay between different microscopic\ndynamic processes play the central role in determining the product of\nemergence. Moreover, the periodically oscillating self-dual patterns\ndemonstrate a classical approach to time crystals.",
        "positive": "Transport Control of Eyring-Fluids along a Transversely-Corrugated\n  Nanoannulus: The volume flow rates of Eyring-fluids inside the wavy-rough nanoannulus were\nobtained analytically (up to the second order) by using the verified model and\nboundary perturbation method. Our results show that the wavy-roughness could\nenhance the flow rate especially for smaller forcing due to the larger\nsurface-to-volume ratio and slip-velocity effect. Meanwhile, the phase shift\nbetween the outer and inner walls of nanoannuli could tune the transport of\nEyring-fluids either forward or backward when the wavy-roughness of a\nnanoannulus is larger enough. Our results could be applied to the flow control\nin nanofluidics as well as biofluidics."
    },
    {
        "anchor": "Spheres and Prolate and Oblate Ellipsoids from an Analytical Solution of\n  Spontaneous Curvature Fluid Membrane Model: An analytic solution for Helfrich spontaneous curvature membrane model (H.\nNaito, M.Okuda and Ou-Yang Zhong-Can, Phys. Rev. E {\\bf 48}, 2304 (1993); {\\bf\n54}, 2816 (1996)), which has a conspicuous feature of representing the circular\nbiconcave shape, is studied. Results show that the solution in fact describes a\nfamily of shapes, which can be classified as: i) the flat plane (trivial case),\nii) the sphere, iii) the prolate ellipsoid, iv) the capped cylinder, v) the\noblate ellipsoid, vi) the circular biconcave shape, vii) the self-intersecting\ninverted circular biconcave shape, and viii) the self-intersecting nodoidlike\ncylinder. Among the closed shapes (ii)-(vii), a circular biconcave shape is the\none with the minimum of local curvature energy.",
        "positive": "Predicting Non-Equilibrium Folding Behavior of Polymer Chains using the\n  Steepest-Entropy-Ascent Quantum Thermodynamic Framework: The Replica Exchange Wang-Landau Method is used to estimate the energy\nlandscape of a polymer composed of a simple hydrophobic and polar sequence\nusing the HP protein model. Calculations of state transitions between the\nenergy levels of the derived energy landscape are made using an equation of\nmotion from the steepest-entropy-ascent quantum thermodynamic (SEAQT)\nframework. The SEAQT framework makes it possible to determine the unique\nkinetic paths from an arbitrary quasi-equilibrium or non-equilibrium initial\nstate to stable equilibrium. Calculations performed with SEAQT require\nsignificantly reduced computational time versus comparable Monte Carlo\nsimulations while providing otherwise unavailable thermodynamic and structural\nproperties. Expected values for state averaged structural parameters are used\nto produce representative reconstructions of the calculated state-based\nevolution. Results show continuous transitions between states with no distinct\nfolding phases. Changes in chain conformations during heating and cooling are\nmore drastic along non-equilibrium paths than along quasi-equilibrium paths. In\naddition, SEAQT-derived kinetics are compared to experimentally derived\nintensity profiles describing the kinetics of the cytochrome c protein using\nRouse dynamic relations."
    },
    {
        "anchor": "Scattering Approach for Fluctuation--Induced Interactions at Fluid\n  Interfaces: We develop the scattering formalism to calculate the interaction between\ncolloidal particles trapped at a fluid interface. Since, in addition to the\ninterface, the colloids may also fluctuate in this system, we implement the\nfluctuation of the boundaries into the scattering formalism and investigate how\nthe interaction between colloids is modified by their fluctuations. This\ngeneral method can be applied to any number of colloids with various geometries\nat an interface. We apply the formalism derived in this work to a system of\nspherical colloids at the interface between two fluid phases. For two spherical\ncolloids, this method very effectively reproduces the previous known results.\nFor three particles we find analytical expressions for the large separation\nasymptotic energies and numerically calculate the Casimir interaction at all\nseparations. Our results show an interesting three body effect for fixed and\nfluctuating colloids. While the three body effect strengthens the attractive\ninteraction between fluctuating colloids, it diminishes the attractive force\nbetween colloids fixed at an interface.",
        "positive": "Exploring the energy landscape of model proteins: a metric criterion for\n  the determination of dynamical connectivity: A method to reconstruct the energy landscape of small peptides is presented\nwith reference to a 2d off--lattice model. The starting point is a statistical\nanalysis of the configurational distances between generic minima and directly\nconnected pairs (DCP). As the mutual distance of DCP is typically much smaller\nthan that of generic pairs, a metric criterion can be established to identify\nthe great majority of DCP. Advantages and limits of this approach are\nthoroughly analyzed for three different heteropolymeric chains. A funnel--like\nstructure of the energy landscape is found in all of the three cases, but the\nescape rates clearly reveal that the native configuration is more easily\naccessible (and is significantly more stable) for the sequence that is expected\nto behave as a real protein."
    },
    {
        "anchor": "Thermally Fluctuating, Semiflexible Sheets in Simple Shear Flow: We perform Brownian dynamics simulations of semiflexible colloidal sheets\nwith hydrodynamic interactions and thermal fluctuations in shear flow. As a\nfunction of the ratio of bending rigidity to shear energy (a dimensionless\nquantity we denote $S$) and the ratio of bending rigidity to thermal energy, we\nobserve a dynamical transition from stochastic flipping to crumpling and\ncontinuous tumbling. This dynamical transition is broadened by thermal\nfluctuations, and the value of $S$ at which it occurs is consistent with the\nonset of chaotic dynamics found for athermal sheets. The effects of different\ndynamical conformations on rheological properties such as viscosity and normal\nstress differences are also quantified. Namely, the viscosity in a dilute\ndispersion of sheets is found to decrease with increasing shear rate\n(shear-thinning) up until the dynamical crumpling transition, at which point it\nincreases again (shear-thickening), and non-zero first normal stress\ndifferences are found that exhibit a local maximum with respect to temperature\nat large $S$ (small shear rate). These results shed light on the dynamical\nbehavior of fluctuating 2D materials dispersed in fluids and should greatly\ninform the design of associated solution processing methods.",
        "positive": "Phase Diagram and Structure Map of Binary Nanoparticle Superlattices\n  from a Lennard-Jones Model: A first principle prediction of the binary nanoparticle phase diagram\nassembled by solvent evaporation has eluded theoretical approaches. In this\npaper, we show that a binary system interacting through Lennard-Jones (LJ)\npotential contains all experimental phases in which nanoparticles are\neffectively described as quasi hard spheres. We report a phase diagram\nconsisting of 53 equilibrium phases, whose stability is quite insensitive to\nthe microscopic details of the potentials, thus giving rise to some type of\nuniversality. Furthermore, we show that binary lattices may be understood as\nconsisting of certain particle clusters, i.e. motifs, which provide a\ngeneralization of the four conventional Frank-Kasper polyhedral units. Our\nresults show that meta-stable phases share the very same motifs as equilibrium\nphases. We discuss the connection with packing models, phase diagrams with\nrepulsive potentials and the prediction of likely experimental superlattices."
    },
    {
        "anchor": "Production of UCN by Downscattering in superfluid He4: Ultra-cold neutrons (UCN) are neutrons with energies so low they can be\nstored in material bottles and magnetic traps. They have been used to provide\nthe currently most accurate experiments on the neutron life time and electric\ndipole moment. UCN can be produced in superfluid Helium at significantly higher\ndensities than by other methods. The predominant production process is usually\nby one phonon emission which can only occur at a single incident neutron energy\nbecause of momentum and energy conservation. However UCN can also be produced\nby multiphonon processes. It is the purpose of this work to examine this\nmultiphonon production of UCN. We look at several different incident neutron\nspectra, including cases where the multiphonon production is significant, and\nsee how the relative importance of multiphonon production is influenced by the\nincident spectrum.",
        "positive": "Trains, tails and loops of partially adsorbed semi-flexible filaments: Polymer adsorption is a fundamental problem in statistical mechanics that has\ndirect relevance to diverse disciplines ranging from biological lubrication to\nstability of colloidal suspensions. We combine experiments with computer\nsimulations to investigate depletion induced adsorption of semi-flexible\npolymers onto a hard-wall. Three dimensional filament configurations of\npartially adsorbed F-actin polymers are visualized with total internal\nreflection fluorescence microscopy. This information is used to determine the\nlocation of the adsorption/desorption transition and extract the statistics of\ntrains, tails and loops of partially adsorbed filament configurations. In\ncontrast to long flexible filaments which primarily desorb by the formation of\nloops, the desorption of stiff, finite-sized filaments is largely driven by\nfluctuating filament tails. Simulations quantitatively reproduce our\nexperimental data and allow us to extract universal laws that explain scaling\nof the adsorption-desorption transition with relevant microscopic parameters.\nOur results demonstrate how the adhesion strength, filament stiffness, length,\nas well as the configurational space accessible to the desorbed filament can be\nused to design the characteristics of filament adsorption and thus engineer\nproperties of composite biopolymeric materials."
    },
    {
        "anchor": "Nematic fluid at a hard wall in the mean field approximation: In the framework of a field theoretical approach we study Maier-Saupe\nnematogenic fluid in contact with a hard wall. The pair interaction potential\nof the considered model consists of an isotropic and an anisotropic Yukawa\nterms. In the mean field approximation the contact theorem is proved. For the\ncase of the nematic director being oriented perpendicular to the wall,\nanalytical expressions for the density and order parameter profiles are\nobtained. It is shown that in a certain thermodynamic region the nematic fluid\nnear the interface can be more diluted and less orientationally ordered than in\nthe bulk region.",
        "positive": "Raft-like domain formation in model lipid-cholesterol aggregation: To understand mechanism of cell-membrane compartmentalization, we studied\ncoarse-grained model systems consisting of lipid and cholesterol molecules.\nCholesterol plays crucial role in lateral phase segregation in the bilayered\nlipid membrane to form cholesterol rich liquid ordered domains, termed as\n`rafts'. In this NVT Molecular Dynamics simulation study, we have investigated\nthe role of cholesterol in raft-like domain formation. The study reveals that\nthe strength of cholesterol interaction is an important factor behind the phase\nsegregation to form cholesterol rich domains, whereas, the relative dipolar\nstrength of lipid and cholesterol molecules controls the formation of\nmulti-bilayered stack."
    },
    {
        "anchor": "Strain Hardening of Polymer Glasses: Entanglements, Energetics, and\n  Plasticity: Simulations are used to examine the microscopic origins of strain hardening\nin polymer glasses. While stress-strain curves for a wide range of temperature\ncan be fit to the functional form predicted by entropic network models, many\nother results are fundamentally inconsistent with the physical picture\nunderlying these models. Stresses are too large to be entropic and have the\nwrong trend with temperature. The most dramatic hardening at large strains\nreflects increases in energy as chains are pulled taut between entanglements\nrather than a change in entropy. A weak entropic stress is only observed in\nshape recovery of deformed samples when heated above the glass transition.\nWhile short chains do not form an entangled network, they exhibit partial shape\nrecovery, orientation, and strain hardening. Stresses for all chain lengths\ncollapse when plotted against a microscopic measure of chain stretching rather\nthan the macroscopic stretch. The thermal contribution to the stress is\ndirectly proportional to the rate of plasticity as measured by breaking and\nreforming of interchain bonds. These observations suggest that the correct\nmicroscopic theory of strain hardening should be based on glassy state physics\nrather than rubber elasticity.",
        "positive": "Ideal wet two-dimensional foams and emulsions with finite contact angle: We present simulations that show that an ideal two-dimensional foam with a\nfinite contact angle develops an inhomogeneity for high liquid fraction $\\phi$.\nIn liquid-liquid emulsions this inhomogeneity is known as flocculation. In the\ncase of an ordered foam this requires a perturbation, but in a disordered foam\ninhomogeneity grows steadily and spontaneously with $\\phi$, as demonstrated in\nour simulations performed with the Surface Evolver."
    },
    {
        "anchor": "Numerical analysis of homogeneous and inhomogeneous intermittent search\n  strategies: A random search is a stochastic process representing the random motion of a\nparticle (denoted as the searcher) that is terminated when it reaches (detects)\na target particle or area the first time. In intermittent search the random\nmotion alternates between two or more motility modes, one of which is\nnon-detecting. An example is the slow diffusive motion as the detecting mode\nand fast, directed ballistic motion as the non-detecting mode, which can lead\nto much faster detection than a purely diffusive search. The transition rate\nbetween the diffusive and the ballistic mode (and back) together with the\nprobability distribution of directions for the ballistic motion defines a\nsearch strategy. If these transition rates and/or probability distributions\ndepend on the spatial coordinates within the search domain it is a spatially\ninhomogeneous search strategy, if both are constant, it is a homogeneous one.\nHere we study the efficiency, measured in terms of the mean first-passage time,\nof spatially homogeneous and inhomogeneous search strategies for three\nparadigmatic search problems: 1) the narrow escape problem, where the searcher\nhas to find a small area on the boundary of the search domain, 2) reaction\nkinetics, which involves the detection of an immobile target in the interior of\na search domain, and 3) the reaction-escape problem, where the searcher first\nneeds to find a diffusive target before it can escape through a narrow region\non the boundary. Using families of spatially inhomogeneous search strategies,\npartially motivated by the spatial organization of the cytoskeleton in living\ncells with a centrosome, we show that they can be made almost always more\nefficient than homogeneous strategies.",
        "positive": "Positron Annihilation Study of Biopolymer Inulin for Understanding its\n  Structural Organization: Inulins are nano-meter size semi-crystalline particles, composed of\noligomeric fructose units. It has been subjected to fine micro-structural\nanalysis under temperature variations using mainly positron annihilation\nspectroscopy. The results show a non-monotonous temperature sensitive behaviour\nof the positron parameters, with considerable variation of its free volume\nsize. The ortho-positronium pick-off component shows a major thermotropic\ntransition at ~320K and a structure loss due to glass transition. Differential\nscanning calorimetry confirms the onset of the major molecular transition\naround the same temperature with an enthalpy change of {\\Delta}H ~379J /gm and\nthermo-gravimetric analysis shows mass loss in the said transition. Keywords:\nInulin, fructose units, positron annihilation spectroscopy, microstructure,\nfree volume analysis. thermotropic transition, thermal analysis."
    },
    {
        "anchor": "Charge Regulating Macro-ions in Salt Solutions: Screening Properties and\n  Electrostatic Interactions: We revisit the charge-regulation mechanism of macro-ions and apply it to\nmobile macro-ions in a bathing salt solution. In particular, we examine the\neffects of correlation between various adsorption/desorption sites and analyze\nthe collective behavior in terms of the solution effective screening\nproperties. We show that such a behavior can be quantified in terms of the\ncharge {\\em asymmetry} of the macro-ions, defined by their preference for a\nnon-zero effective charge, and their {\\em donor/acceptor} propensity for\nexchanging salt ions with the bathing solution. Asymmetric macro-ions tend to\nincrease the screening, while symmetric macro-ions can in some cases decrease\nit. Macro-ions that are classified as donors display a rather regular behavior,\nwhile those that behave as acceptors exhibit an anomalous non-monotonic Debye\nlength. The screening properties, in their turn, engender important\nmodifications to the disjoining pressure between two charged surfaces. Our\nfindings are in particular relevant for solutions of proteins, whose exposed\namino acids can undergo charge dissociation/association processes to/from the\nbathing solution, and can be considered as a solution of charged regulated\nmacro-ions, as analyzed here.",
        "positive": "Simulations of Thin Polymer Films on Flat and Curved Substrates: We report molecular dynamics simulation results on the equilibrium properties\nof polymer thin films adsorbed onto flat and curved substrates. We first\nsystematically determine the contact angle of polymer droplets on flat\nsubstrates as a function of the substrate-monomer adsorption strength and\ndegree of polymerization. Focussing on the fully wetted regime, we then\ninvestigate the effect of the substrate's topography on the polymer film\nconfiguration by using substrates with varying mean curvature. We find that\npolymer chains close to the substrate are significantly stretched (compressed)\nin regions of high negative (positive) mean curvature. Further, we find partial\ndewetting near regions of high mean curvature for thin polymer films. For\nthicker films, the polymers fully cover the substrate and the shape of the\nliquid-vapor interface largely follows the shape of the substrate. As the film\nthickness is increased further, the liquid-vapor interface becomes completely\nflat. These simulation results are corroborated by analytic calculations using\na simplified continuum model that treats the adsorbed polymers as an\nincompressible medium. Our findings show how the substrate topography\ninfluences the conformation of individual chains as well as the shape of the\nentire film."
    },
    {
        "anchor": "Anomalous snapping behavior in asymmetrically constrained elastic strips: When a flat elastic strip is compressed along its axis, it is bent in one of\ntwo possible directions via spontaneous symmetry breaking and forms a\ncylindrical arc, a phenomenon well known as Euler buckling. When this\ncylindrical section is pushed in the other direction, the bending direction can\nsuddenly reverse. This instability is called snap-through buckling and is one\nof the elementary shape transitions in a prestressed thin structure. Combining\nexperiments and theory, we study snap-buckling of an elastic strip with one end\nhinged and the other end clamped. These asymmetric boundary constraints break\nthe intrinsic symmetry of the strip, generating rich exotic mechanical\nbehaviors including largely hysteretic but reproducible force responses and\nswitch-like discontinuous shape changes. We establish the set of exact\nanalytical solutions that fully explain all of our major experimental and\nnumerical findings. Asymmetric boundary conditions arise naturally in diverse\nsituations when a thin object is in contact with a solid surface at one end,\nbut their profound consequences for the buckling mechanics have been largely\noverlooked to date. The idea of introducing asymmetry through boundary\nconditions would yield new insight into complex and programmable\nfunctionalities in material and industrial design.",
        "positive": "Statistical mechanics of thin spherical shells: We explore how thermal fluctuations affect the mechanics of thin amorphous\nspherical shells. In flat membranes with a shear modulus, thermal fluctuations\nincrease the bending rigidity and reduce the in-plane elastic moduli in a\nscale-dependent fashion. This is still true for spherical shells. However, the\nadditional coupling between the shell curvature, the local in-plane stretching\nmodes and the local out-of-plane undulations, leads to novel phenomena. In\nspherical shells thermal fluctuations produce a radius-dependent negative\neffective surface tension, equivalent to applying an inward external pressure.\nBy adapting renormalization group calculations to allow for a spherical\nbackground curvature, we show that while small spherical shells are stable,\nsufficiently large shells are crushed by this thermally generated \"pressure\".\nSuch shells can be stabilized by an outward osmotic pressure, but the effective\nshell size grows non-linearly with increasing outward pressure, with the same\nuniversal power law exponent that characterizes the response of fluctuating\nflat membranes to a uniform tension."
    },
    {
        "anchor": "Stretching necklaces: Polyelectrolytes in poor solvents show a necklace structure where collapsed\npolymer pearls are linked to stretched strings. In the present paper the\nelasticity of such chains is studied in detail. Different deformation regimes\nare addressed. The first is the continuous regime, where many pearls are\npresent. A continuous force extension relation ship is calculated. The main\ncontribution comes from the tension balance and the electrostatic repulsion of\nconsecutive pearls. The main correction term stems from the finite size of the\npearls, which monitors their surface energy. For a finite amount of pearls\ndiscontinuous stretching is predicted. Finally counterion effects are discussed\nqualitatively.",
        "positive": "Spinodal decomposition and phase separation in polar active matter: We develop and study the hydrodynamic theory of flocking with autochemotaxis.\nThis describes large collections of self-propelled entities all spontaneously\nmoving in the same direction, each emitting a substance which attracts the\nothers (e.g., ants). The theory combines features of the Keller-Segel model for\nautochemotaxis with the Toner-Tu theory of flocking. We find that sufficiently\nstrong autochemotaxis leads to an instability of the uniformly moving state\n(the ``flock\"), in which bands of different density form moving parallel to the\nmean flock velocity with different speeds. These bands, which are reminiscent\nof ant trails, coarsen over time to reach a phase-separated state, in which one\nhigh density and one low density band fill the entire system. The same\ninstability, described by the same hydrodynamic theory, can occur in flocks\nphase separating due to any microscopic mechanism (e.g., sufficiently strong\nattractive interactions). Although in many ways analogous to equilibrium phase\nseparation via spinodal decomposition, the two steady state densities here are\ndetermined not by a common tangent construction, as in equilibrium, but by an\nuncommon tangent construction very similar to that found for motility induced\nphase separation (MIPS) of disordered active particles. Our analytic theory\nagrees well with our numerical simulations of our equations of motion."
    },
    {
        "anchor": "We the Droplets: A Constitutional Approach to Active and Self-Propelled\n  Emulsions: The field of active matter, and particularly active emulsions, is growing\nrapidly, with significant progress made recently on both theoretical and\nexperimental fronts. Here, we summarize experimental research progress related\nto active droplets. The constitution of active droplets, in particular the\nchemical compositions and structure of interfaces, is critical. We discuss how\nemulsion properties such as mechanism of motion, speed, trajectory, interaction\nstrength, and lifetime are related to the droplet composition. We consider not\nonly traditional single emulsions but also more complex variants, such as Janus\ndroplets, Pickering emulsions, and multiple emulsions. Active behavior of\nisolated droplets as well as pairwise and multibody interactions between\ndroplets is described. The influence of physical barriers that shape the local\nchemical gradients and fluid flow is also highlighted. This review provides\nperspective on the past, current, promising future experimental research\ndirections in active droplet research.",
        "positive": "Small-world networks and the conformation space of a lattice polymer\n  chain: We map the conformation space of a simple lattice polymer chain to a network,\nwhere (i) the vertices of the network have a one-to-one correspondence to the\nconformations of the chain, and (ii) a link between two vertices indicates the\npossibility of switching from one conformation to the other by a single Monte\nCarlo move of the chain. We find that the geometric properties of this network\nare similar to those of small-world networks, namely, the diameter of\nconformation space increases, for large networks, as the logarithm of the\nnumber of conformations, while locally the network appears to have low\ndimensionality."
    },
    {
        "anchor": "Dynamics of Fluid Vesicles in Flow through Structured Microchannels: The dynamics of fluid vesicles is studied under flow in microchannels, in\nwhich the width varies periodically along the channel. Three types of flow\ninstabilities of prolate vesicles are found. For small quasi-spherical vesicles\n-- compared to the average channel width -- perturbation theory predicts a\ntransition from a state with orientational oscillations of a fixed prolate\nshape to a state with shape oscillations of symmetrical ellipsoidal or\nbullet-like shapes with increasing flow velocity. Experimentally, such\norientational oscillations are observed during the slow migration of a vesicle\ntowards the centerline of the channel. For larger vesicles, mesoscale\nhydrodynamics simulations and experiments show similar symmetric shape\noscillation at reduced volumes $V^* \\gtrsim 0.9$. However, for non-spherical\nvesicles with $V^* \\lesssim 0.9$, shapes are found with two symmetric or a\nsingle asymmetric tail.",
        "positive": "Transport of Particles in Liquid Crystals: Colloidal particles in a liquid crystal (LC) behave very differently from\ntheir counterparts in isotropic fluids. Elastic nature of the orientational\norder and surface anchoring of the director cause long-range anisotropic\ninteractions and lead to the phenomenon of levitation. The LC environment\nenables new mechanisms of particle transport that are reviewed in this work.\nAmong them the motion of particles caused by gradients of the director, and\neffects in the electric field: backflow powered by director reorientations,\ndielectrophoresis in LC with varying dielectric permittivity and LC-enabled\nnonlinear electrophoresis with velocity that depends on the square of the\napplied electric field and can be directed differently from the field\ndirection."
    },
    {
        "anchor": "Liquid-liquid phase separation of a surfactant-solubilized membrane\n  protein: The phase behavior of membrane proteins stems from a complex synergy with the\namphiphilic molecules required for their solubilization. We show that\nionization of a pH-sensitive surfactant, LDAO, bound to a bacterial\nphotosynthetic protein, the Reaction Center (RC), leads in a narrow pH range to\nprotein liquid-liquid phase separation in surprisingly stable `droplets',\nforerunning reversible aggregation at lower pH. Phase segregation is promoted\nby increasing temperature and hindered by adding salt. RC light-absorption and\nphotoinduced electron cycle are moreover strongly affected by phase\nsegregation.",
        "positive": "Dynamics of proteins: Light scattering study of dilute and dense\n  colloidal suspensions of eye lens homogenates: We report a dynamic light scattering study on protein suspensions of bovine\nlens homogenates at conditions (pH and ionic strength) similar to the\nphysiological ones. Light scattering data were collected at two temperatures,\n20 oC and 37 oC, over a wide range of concentrations from the very dilute limit\nup to the dense regime approaching to the physiological lens concentration. A\ncomparison with experimental data from intact bovine lenses was advanced\nrevealing differences between dispersions and lenses at similar concentrations.\nIn the dilute regime two scattering entities were detected and identified with\nthe long-time, self-diffusion modes of alpha-crystallins and their aggregates,\nwhich naturally exist in lens nucleus. Self-diffusion coefficients are\ntemperature insensitive, whereas the collective diffusion coefficient depends\nstrongly on temperature revealing a reduction of the net repulsive\ninterparticle forces with lowering temperature. While there are no rigorous\ntheoretical approaches on particle diffusion properties for multi-component,\nnon-ideal hard-sphere, polydispersed systems, as the suspensions studied here,\na discussion of the volume fraction dependence of the long-time, self-diffusion\ncoefficient in the context of existing theoretical approaches was undertaken.\nThis study is purported to provide some insight into the complex light\nscattering pattern of intact lenses and the interactions between the\nconstituent proteins that are responsible for lens transparency. This would\nlead to understand basic mechanisms of specific protein interactions that lead\nto lens opacification (cataract) under pathological conditions."
    },
    {
        "anchor": "Trapping of Single Nano-Objects in Dynamic Temperature Fields: In this article we explore the dynamics of a Brownian particle in a\nfeedback-free dynamic thermophoretic trap. The trap contains a focused laser\nbeam heating a circular gold structure locally and creating a repulsive thermal\npotential for a Brownian particle. In order to confine a particle the heating\nbeam is steered along the circumference of the gold structure leading to a\nnon-trivial motion of the particle. We theoretically find a stability condition\nby switching to a rotating frame, where the laser beam is at rest. Particle\ntrajectories and stable points are calculated as a function of the laser\nrotations frequency and are experimentally confirmed. Additionally, the effect\nof Brownian motion is considered. The present study complements the dynamic\nthermophoretic trapping with a theoretical basis and will enhance the\napplicability in micro- and nanofluidic devices.",
        "positive": "Bending control and instability of functionally graded dielectric\n  elastomers: A rectangular plate of dielectric elastomer exhibiting gradients of material\nproperties through its thickness will deform inhomogeneously when a potential\ndifference is applied to compliant electrodes on its major surfaces, because\neach plane parallel to the major surfaces will expand or contract to a\ndifferent extent. Here we study the voltage-induced bending response of a\nfunctionally graded dielectric plate on the basis of the nonlinear theory of\nelectro-elasticity, when both the elastic shear modulus and the electric\npermittivity change with the thickness coordinate. The theory is illustrated\nfor a neo-Hookean electro-elastic energy function with the shear modulus and\npermittivity varying linearly across the thickness. We find that in general the\nbending angle increases with the potential difference provided the Hessian\nremains positive, but instability can arise as the potential difference\nincreases and the Hessian vanishes. We derive the Hessian criterion for\npredicting the instability, and show how the material gradients can be tuned to\ncontrol the bending shape, and to delay or promote the onset of the instability\nof the elastomer."
    },
    {
        "anchor": "Reorientation dynamics in thin glassy films: We present a study of orientational relaxation dynamics in thin films of a\nlow-molecular-weight glass-former as a function of temperature and film\nthickness. The relaxation is probed by second-harmonic generation after release\nof a poling electric field. From the measured decays of the second-harmonic\nsignal and their fitting with a stretched exponential, we can determine the\ndistribution of relaxation times in the system. As temperature decreases from\nabove the glass transition, we observe that the width of the distribution first\nincreases under confinement, but that deeper in the glassy state, confinement\nhas no effect anymore on the dynamics.",
        "positive": "Screening of ion-ion correlations in electrolyte solutions adsorbed in\n  charged disordered matrices: Application of replica Ornstein-Zernike\n  equations: The replica Ornstein-Zernike equations for an electrolyte adsorbed in a\ncharged, disordered matrix were applied to a model, where both subsystems\nconsisted of points carrying a single (positive or negative) charge. While the\nsystem as a whole was electroneutral, each of the subsytems had a net charge.\nThe results of this study are compared with the ones previously obtained, where\nthe interactions in such a system were considered to be the same as in the case\nof electroneutral subsystems."
    },
    {
        "anchor": "Non-linear rheology of a nanoconfined simple fluid: We probe the rheology of the model liquid octamethylcyclotetrasiloxane\n(OMCTS) confined into molecularly thin films, using a unique Surface Forces\nApparatus allowing to explore a large range of shear rates and confinement. We\nthus show that OMCTS under increasing confinement exhibits the viscosity\nenhancement and the non-linear flow properties characteristic of a sheared\nsupercooled liquid approaching its glass transition. Besides, we study the\ndrainage of confined OMCTS via the propagation of \"squeeze-out\" fronts. The\nhydrodynamic model proposed by Becker and Mugele [Phys. Rev. Lett. {\\bf 91},\n166104 (2003)] to describe such front dynamics leads to a conclusion in\napparent contradiction with the dynamical slowdown evidenced by rheology\nmeasurements, which suggests that front propagation is not controlled by large\nscale flow in the confined films.",
        "positive": "Rheology of Granular Materials: Dynamics in a Stress Landscape: We present a framework for analyzing the rheology of dense driven granular\nmaterials, based on a recent proposal of a stress-based ensemble. In this\nensemble fluctuations in a granular system near jamming are controlled by a\ntemperature-like parameter, the angoricity, which is conjugate to the stress of\nthe system. In this paper, we develop a model for slowly driven granular\nmaterials based on the stress ensemble and the idea of a landscape in stress\nspace. The idea of an activated process driven by the angoricity has been shown\nby Behringer et al (2008) to describe the logarithmic strengthening of granular\nmaterials. Just as in the Soft Glassy Rheology (SGR) picture, our model\nrepresents the evolution of a small patch of granular material (a mesoscopic\nregion) in a stress-based trap landscape. The angoricity plays the role of the\nfluctuation temperature in SGR. We determine (a) the constitutive equation, (b)\nthe yield stress, and (c) the distribution of stress dissipated during granular\nshearing experiments, and compare these predictions to experiments of Hartley &\nBehringer (2003)."
    },
    {
        "anchor": "Mechanical prions: Self-assembling microstructures: Prions are misfolded proteins that transmit their structural arrangement to\nneighboring proteins. In biological systems, prion dynamics can produce a\nvariety of complex functional outcomes. Yet, an understanding of prionic causes\nhas been hampered by the fact that few computational models exist that allow\nfor experimental design, hypothesis testing, and control. Here, we identify\nessential prionic properties and present a biologically inspired model of\nprions using simple mechanical structures capable of undergoing complex\nconformational change. We demonstrate the utility of our approach by designing\na prototypical mechanical prion and validating its properties experimentally.\nOur work provides a design framework for harnessing and manipulating prionic\nproperties in natural and artificial systems.",
        "positive": "Smoothening Transition of a Two-Dimensional Pressurized Polymer Ring: We revisit the problem of a two-dimensional polymer ring subject to an\ninflating pressure differential. The ring is modeled as a freely jointed closed\nchain of N monomers. Using a Flory argument, mean-field calculation and Monte\nCarlo simulations, we show that at a critical pressure, $p_c \\sim N^{-1}$, the\nring undergoes a second-order phase transition from a crumpled, random-walk\nstate, where its mean area scales as $<A> \\sim N$, to a smooth state with\n$<A>\\sim N^2$. The transition belongs to the mean-field universality class. At\nthe critical point a new state of polymer statistics is found, in which\n$<A>\\sim N^{3/2}$. For $p>>p_c$ we use a transfer-matrix calculation to derive\nexact expressions for the properties of the smooth state."
    },
    {
        "anchor": "Shear-melting of a hexagonal columnar crystal by proliferation of\n  dislocations: A hexagonal columnar crystal undergoes a shear-melting transition above a\ncritical shear rate or stress. We combine the analysis of the shear-thinning\nregime below the melting with that of synchrotron X-ray scattering data under\nshear and propose the melting to be due to a proliferation of dislocations,\nwhose density is determined by both techniques to vary as a power law of the\nshear rate with a 2/3 exponent, as expected for a creep model of crystalline\nsolids. Moreover, our data suggest the existence under shear of a line hexatic\nphase, between the columnar crystal and the liquid phase.",
        "positive": "Ripple-like instability in the simulated gel phase of finite size\n  phosphocholine bilayers: Atomistic molecular dynamics simulations have reached a degree of maturity\nthat makes it possible to investigate the lipid polymorphism of model bilayers\nover a wide range of temperatures. However if both the fluid $L_{\\alpha}$ and\ntilted gel $L_{\\beta'}$ states are routinely obtained, the $P_{\\beta'}$ ripple\nphase of phosphatidylcholine lipid bilayers is still unsatifactorily described.\nPerforming simulations of lipid bilayers made of different numbers of DPPC\n(1,2-dipalmitoylphosphatidylcholine) molecules ranging from 32 to 512, we\ndemonstrate that the tilted gel phase $L_{\\beta'}$ expected below the\npre-transition cannot be obtained for large systems ($>$ 94 DPPC molecules)\nthrough common simulations settings or temperature treatments. Large systems\nare instead found in a disordered gel phase which display configurations,\ntopography and energies reminiscent from the ripple phase $P_{\\beta'}$ observed\nbetween the pretransition and the main melting transition. We show how the\nstate of the bilayers below the pretransition can be controlled and depends on\nthermal history and conditions of preparations. A mechanism for the observed\ntopographic instability is suggested."
    },
    {
        "anchor": "Disordering Transitions and Peak Effect in Polydisperse Particle Systems: We show numerically that in a binary system of Yukawa particles, a dispersity\ndriven disordering transition occurs. In the presence of quenched disorder this\ndisordering transition coincides with a marked increase in the depinning\nthreshold, known as a peak effect. We find that the addition of poorly pinned\nparticles can increase the overall pinning in the sample by increasing the\namount of topological disorder present. If the quenched disorder is strong\nenough to create a significant amount of topological disorder in the\nmonodisperse system, addition of a poorly pinned species generates further\ndisorder but does not produce a peak in the depinning force. Our results\nindicate that for binary mixtures, optimal pinning occurs for topological\ndefect fraction densities of 0.2 to 0.25. For defect densities below this\nrange, the system retains orientational order. We determine the effect of the\npinning density, strength, and radius on the depinning peak and find that the\npeak effect is more pronounced in weakly pinning systems.",
        "positive": "A non-local rheology for granular flows across yield conditions: The rheology of dense granular flows is studied numerically in a shear cell\ncontrolled at constant pressure and shear stress, confined between two granular\nshear flows. We show that a liquid state can be achieved even far below the\nyield stress, whose flow can be described with the same rheology as above the\nyield stress. A non-local constitutive relation is derived from dimensional\nanalysis through a gradient expansion and calibrated using the spatial\nrelaxation of velocity profiles observed under homogeneous stresses. Both for\nfrictional and frictionless grains, the relaxation length is found to diverge\nas the inverse square-root of the distance to the yield point, on both sides of\nthat point."
    },
    {
        "anchor": "Analysis of Two-State Folding Using Parabolic Approximation I:\n  Hypothesis: A model which treats the denatured and native conformers of\nspontaneously-folding fixed two-state systems as being confined to harmonic\nGibbs energy-wells has been developed.Within the assumptions of this model the\nGibbs energy functions of the denatured (DSE) and the native state (NSE)\nensembles are described by parabolas, with the mean length of the reaction\ncoordinate (RC) being given by the temperature-invariant denaturant m\nvalue.Consequently, the ensemble-averaged position of the transition state\nensemble (TSE) along the RC, and the ensemble-averaged Gibbs energy of the TSE\nare determined by the intersection of the DSE and the NSE-parabolas. The\nequations derived enable equilibrium stability and the rate constants to be\nrationalized in terms of the mean and the variance of the Gaussian distribution\nof the solvent accessible surface area of the conformers in the DSE and the\nNSE. The implications of this model for protein folding are discussed.",
        "positive": "Two-component dynamics and the liquid-like to gas-like crossover in\n  supercritical water: Molecular-scale dynamics in sub- to super-critical water is studied with\ninelastic X-ray scattering and molecular dynamics simulations. The obtained\nlongitudinal current correlation spectra can be decomposed into two main\ncomponents: a low-frequency (LF), gas-like component and a high-frequency (HF)\ncomponent arising from the O--O stretching mode between hydrogen-bonded\nmolecules, reminiscent of the longitudinal acoustic mode in ambient water. With\nincreasing temperature, the hydrogen-bond network diminishes and the spectral\nweight shifts from HF to LF, leading to a transition from liquid-like to\ngas-like dynamics with rapid changes around the Widom line."
    },
    {
        "anchor": "Time-dependent inertia of self-propelled particles: the Langevin rocket: Many self-propelled objects are large enough to exhibit inertial effects but\nstill suffer from environmental fluctuations. The corresponding basic equations\nof motion are governed by active Langevin dynamics which involve inertia,\nfriction and stochastic noise for both the translational and orientational\ndegrees of freedom coupled via the self-propulsion along the particle\norientation. In this paper, we generalize the active Langevin model to\ntime-dependent parameters and explicitly discuss the effect of time-dependent\ninertia for achiral and chiral particles. Realizations of this situation are\nmanifold ranging from minirockets which are self-propelled by burning their own\nmass, dust particles in plasma which lose mass by evaporating material to\nwalkers with expiring activity. Here we present analytical solutions for\nseveral dynamical correlation functions such as the mean-square displacement\nand the orientational and velocity autocorrelation functions. If the parameters\nexhibit a slow power-law in time, we obtain anomalous superdiffusion with a\nnon-trivial dynamical exponent. Finally we constitute the \"Langevin rocket\"\nmodel by including orientational fluctuations in the traditional Tsiolkovsky\nrocket equation. We calculate the mean reach of the Langevin rocket and discuss\ndifferent mass ejection strategies to maximize it. Our results can be tested in\nexperiments on macroscopic robotic or living particles or in self-propelled\nmesoscopic objects moving in media of low viscosity such as complex plasma.",
        "positive": "Emergence of an Ising critical regime in the clustering of 1D soft\n  matter revealed through string variables: Soft matter systems are renowned for being able to display complex emerging\nphenomena such as clustering phases. Recently, a surprising quantum phase\ntransition has been revealed in a one-dimensional (1D) system composed of\nbosons interacting via a pairwise soft potential in the continuum. It was shown\nthat the spatial coordinates undergoing two-particle clustering could be mapped\ninto quantum spin variables of a 1D transverse Ising model. In this work we\ninvestigate the manifestation of an analogous critical phenomenon in 1D\nclassical fluids of soft particles in the continuum. In particular, we study\nthe low-temperature behavior of three different classical models of 1D soft\nmatter, whose inter-particle interactions allow for clustering. The same string\nvariables highlight that, at the commensurate density for the two-particle\ncluster phase, the peculiar pairing of neighboring soft particles can be\nnontrivially mapped onto a 1D discrete classical Ising model. We also observe a\nrelated phenomenon, namely the presence of an anomalous peak in the\nlow-temperature specific heat, thus indicating the emergence of Schottky\nphenomenology in a non-magnetic fluid."
    },
    {
        "anchor": "Velocity fields and particle trajectories for bed load over subaqueous\n  barchan dunes: This paper presents an experimental investigation of moving grains over\nsubaqueous barchan dunes that consisted of spherical glass beads of known\ngranulometry. Prior to each test run, a pre-determined quantity of grains was\npoured inside a closed conduit, and the grains settled on its bottom wall\nforming one conical heap. As different turbulent water flows were imposed, each\nheap evolved to a barchan dune, which was filmed with a high-speed camera. An\nimage processing code was written to identify some of the moving grains and\ncompute their velocity fields and trajectories. Our results show that the\nvelocity of grains varies along the barchan dune, with higher velocities\noccurring close to the dune centroid, and that grains trajectories are\nintermittent. Depending on the region over the dune, we found that the velocity\nfields present values within 1 and 10 % of the cross-sectional mean velocity of\nthe fluid. Considering the average trajectories of grains moving over a given\ndune, their mean displacement varies within 30 and 60 grain diameters and their\ncharacteristic velocities within 10 and 20 % of the cross-sectional mean\nvelocity of the fluid. The displacement time varies between 30 and 90 % of the\nsettling time, and it seems to have two asymptotic behaviors: one close to bed\nload inception and other far from it. When compared with bed load over a plane\nbed, we observe that grains have the same mean velocity, but they travel\ndistances up to 5 times larger, with higher densities of moving grains.",
        "positive": "How cells wrap around virus-like particles using extracellular\n  filamentous protein structures: Nanoparticles, such as viruses, can enter cells via endocytosis. During\nendocytosis, the cell surface wraps around the nanoparticle to effectively eat\nit. Prior focus has been on how nanoparticle size and shape impacts\nendocytosis. However, inspired by the noted presence of extracellular vimentin\naffecting viral and bacteria uptake, as well as the structure of coronaviruses,\nwe construct a computational model in which both the cell-like construct and\nthe virus-like construct contain filamentous protein structures protruding from\ntheir surfaces. We then study the impact of these additional degrees of freedom\non viral wrapping. We find that cells with an optimal density of filamentous\nextracellular components (ECCs) are more likely to be infected as they uptake\nthe virus faster and use relatively less cell surface area per individual\nvirus. At the optimal density, the cell surface folds around the virus, and\nfolds are faster and more efficient at wrapping the virus than crumple-like\nwrapping. We also find that cell surface bending rigidity helps generate folds,\nas bending rigidity enhances force transmission across the surface. However,\nchanging other mechanical parameters, such as the stretching stiffness of\nfilamentous ECCs or virus spikes, can drive crumple-like formation of the cell\nsurface. We conclude with the implications of our study on the evolutionary\npressures of virus-like particles, with a particular focus on the cellular\nmicroenvironment that may include filamentous ECCs."
    },
    {
        "anchor": "Chiral edge fluctuations of colloidal membranes: We study edge fluctuations of a flat colloidal membrane comprised of a\nmonolayer of aligned filamentous viruses. Experiments reveal that a peak in the\nspectrum of the in-plane edge fluctuations arises for sufficiently strong virus\nchirality. Accounting for internal liquid crystalline degrees of freedom by the\nlength, curvature, and geodesic torsion of the edge, we calculate the spectrum\nof the edge fluctuations. The theory quantitatively describes the experimental\ndata, demonstrating that chirality couples in-plane and out-of-plane edge\nfluctuations to produce the peak.",
        "positive": "Run stop shock, run shock run: Spontaneous and stimulated gait-switching\n  in a unicellular octoflagellate: In unicellular flagellates, growing evidence suggests control over a complex\nrepertoire of swimming gaits is conferred intracellularly by ultrastructural\ncomponents, resulting in motion that depends on flagella number and\nconfiguration. We report the discovery of a novel, tripartite motility in an\noctoflagellate alga, comprising a forward gait ($run$), a fast knee-jerk\nresponse with dramatic reversals in beat waveform ($shock$), and, remarkably,\nlong quiescent periods ($stop$) within which the flagella quiver. In a reaction\ngraph representation, transition probabilities show that gait switching is only\nweakly reversible. Shocks occur spontaneously but are also triggered by direct\nmechanical contact. In this primitive alga, the capability for a millisecond\nstop-start switch from rest to full speed implicates an early evolution of\nexcitable signal transduction to and from peripheral appendages."
    },
    {
        "anchor": "Investigation of DNA denaturation in Peyrard-Bishop-Dauxois model by\n  molecular dynamics method: The phase transition of $(PolyA/PolyT)_{100}$ duplex into the denaturated\nstate is studied in the Peyrard-Bishop-Dauxois model by the method of direct\nmolecular-dynamical modeling. The temperature dependencies of the total energy\nand heat capacity of the duplex are calculated. The approach applied can be\nused to calculate the statistical properties of the duplexes of any length and\nnucleotide composition.",
        "positive": "Casimir effect in swimmer suspensions: We show that the Casimir effect can emerge in microswimmer suspensions. In\nprinciple, two effects conspire against the development of Casimir effects in\nswimmer suspensions. First, at low Reynolds number, the force on any closed\nvolume vanishes, but here the relevant effect is the drag by the flow produced\nby the swimmers, which can be finite. Second, the fluid velocity and the\npressure are linear on the swimmer force dipoles, and averaging over the\nswimmer orientations would lead to a vanishing effect. However, being the\nsuspension a discrete system, the noise terms of the coarse grained equations\ndepend on the density, which itself fluctuates, resulting in effective\nnon-linear dynamics. Applying the tools developed for other non-equilibrium\nsystems to general coarse grained equations for swimmer suspensions, the\nCasimir drag is computed on immersed objects, and it is found to depend on the\ncorrelation function between the rescaled density and dipolar density fields.\nBy introducing a model correlation function with medium range order, explicit\nexpressions are obtained for the Casimir drag on a body. When the correlation\nlength is much larger than the microscopic cutoff, the average drag is\nindependent of the correlation length, with a range that depends only on the\nsize of the immersed bodies."
    },
    {
        "anchor": "Solute particle near a nanopore: influence of size and surface\n  properties on the solvent-mediated forces: Nanoscopic pores are used in various systems to attract nanoparticles. In\ngeneral the behaviour is a result of two types of interactions: the material\nspecific affinity and the solvent-mediated influence also called the depletion\nforce. The latter is more universal but also much more complex to understand\nsince it requires modeling both the nanoparticle and the solvent. Here, we\nemployed classical density functional theory to determine the forces acting on\na nanoparticle near a nanoscopic pore as a function of its hydrophobicity and\nits size. A simple capillary model is constructed to predict those depletion\nforces for various surface properties. For a nanoscopic pore, complexity arises\nfrom both the specific geometry and the fact that hydrophobic pores are not\nnecessarily filled with liquid. Taking all of these effects into account and\nincluding electrostatic effects, we establish a phase diagram describing the\nentrance and the rejection of the nanoparticle from the pore.",
        "positive": "Wall slip in primitive chain network simulations of shear startup of\n  entangled polymers and its effect on the shear stress undershoot: In some recent experiments on entangled polymers of stress growth in startup\nof fast shear flows an undershoot in the shear stress is observed following the\novershoot, i.e., before approaching the steady state. Whereas tumbling of the\nentangled chain was proposed to be at its origin, here we investigate another\npossible cause for the stress undershoot, i.e., slippage at the interface\nbetween polymer and solid wall. To this end, we extend the primitive chain\nnetwork model to include slip at the interface between entangled polymeric\nliquids and solid walls with grafted polymers. We determine the slip velocity\nat the wall, and the shear rate in the bulk, by imposing that the shear stress\nin the bulk polymers is equal to that resulting from the polymers grafted at\nthe wall. After confirming that the predicted results for the steady state are\nreasonable, we examine the transient behavior. The simulations confirm that\nslippage weakens the magnitude of the stress overshoot, as reported earlier.\nThe undershoot is also weakened, or even disappears, because of a reduced\ncoherence in molecular tumbling. In other words, the disentanglement between\ngrafted and bulk chains, occurring throughout the stress overshoot region, does\nnot contribute to the stress undershoot."
    },
    {
        "anchor": "Shear-induced structures versus flow instabilities: The Taylor-Couette flow of a dilute micellar system known to generate\nshear-induced structures is investigated through simultaneous rheometry and\nultrasonic imaging. We show that flow instabilities must be taken into account\nsince both the Reynolds number and the Weissenberg number may be large. Before\nnucleation of shear-induced structures, the flow can be inertially unstable,\nbut once shear-induced structures are nucleated the kinematics of the flow\nbecome chaotic, in a pattern reminiscent of the inertio-elastic turbulence\nknown in dilute polymer solutions. We outline a general framework for the\ninterplay between flow instabilities and flow-induced structures.",
        "positive": "Liquid Crystal Distortions Revealed by an Octupolar Tensor: The classical theory of liquid crystal elasticity as formulated by Oseen and\nFrank describes the (orientable) optic axis of these soft materials by a\ndirector $\\mathbf{n}$. The ground state is attained when $\\mathbf{n}$ is\nuniform in space; all other states, which have a non-vanishing gradient\n$\\nabla\\mathbf{n}$, are distorted. This paper proposes an algebraic (and\ngeometric) way to describe the local distortion of a liquid crystal by\nconstructing from $\\mathbf{n}$ and $\\nabla\\mathbf{n}$ a third-rank, symmetric\nand traceless tensor $\\mathbf{A}$ (the octupolar tensor). The (nonlinear)\neigenvectors of $\\mathbf{A}$ associated with the local maxima of its cubic form\n$\\Phi$ on the unit sphere (its octupolar potential) designate the directions of\ndistortion concentration. The octupolar potential is illustrated geometrically\nand its symmetries are charted in the space of distortion characteristics, so\nas to educate the eye to capture the dominating elastic modes. Special\ndistortions are studied, which have everywhere either the same octupolar\npotential or one with the same shape, but differently inflated."
    },
    {
        "anchor": "Far-field theory for trajectories of magnetic ellipsoids in rectangular\n  and circular channels: We report a method to control the positions of ellipsoidal magnets in flowing\nchannels of rectangular or circular cross section at low Reynolds number.A\nstatic uniform magnetic field is used to pin the particle orientation, and the\nparticles move with translational drift velocities resulting from hydrodynamic\ninteractions with the channel walls which can be described using Blake's image\ntensor.Building on his insights, we are able to present a far-field theory\npredicting the particle motion in rectangular channels, and validate the\naccuracy of the theory by comparing to numerical solutions using the boundary\nelement method.We find that, by changing the direction of the applied magnetic\nfield, the motion can be controlled so that particles move either to a curved\nfocusing region or to the channel walls.We also use simulations to show that\nthe particles are focused to a single line in a circular channel.Our results\nsuggest ways to focus and segregate magnetic particles in lab-on-a-chip\ndevices.",
        "positive": "The Writhe Distribution Of Stretched Polymers: Motivated by experiments in which single DNA molecules are stretched and\ntwisted we consider a perturbative approach around very high forces, where we\ndetermine the writhe distribution in a simple, analytically tractable model.\nOur results are in agreement with recent simulations and experiments."
    },
    {
        "anchor": "A density functional theory approach to interpret elastowetting of\n  hydrogels: Sessile hydrogel drops on rigid surfaces exhibit wetting/contact morphology\nintermediate between liquid drops and glass spheres. Using density functional\ntheory, we reveal the contact forces acting between a hydrogel and a rigid\nglass surface. We show that while transitioning from liquid-like to solid-like\nhydrogels, there exists a critical hydrogel elasticity which enables a switch\nfrom attractive to repulsive interaction with the underlying rigid glass\nsurface. Our theoretical model is validated by experimental observations of\nsessile Polyacrylamide (PAAm) hydrogels of varying elasticity on glass\nsurfaces. Further, the proposed model successfully approaches Young's law in\nthe pure liquid limit and work of adhesion in the glassy limit. Lastly, we show\na modified contact angle relation taking into account the hydrogel elasticity\nto explain the features of a distinct hydrogel foot.",
        "positive": "Interpretation of the vibrational spectra of glassy polymers using\n  coarse-grained simulations: The structure and vibrational density of states (VDOS) of polymer glasses are\ninvestigated using numerical simulations based on the classical Kremer-Grest\nbead-spring model. We focus on the roles of chain length and bending stiffness,\nthe latter being set by imposing three-body angular potentials along chain\nbackbones. Upon increasing the chain length and bending stiffness, structural\nreorganisation leads to volumetric expansion of the material and build-up of\ninternal stresses. The VDOS has two dominant bands: a low frequency one\ncorresponding to inter- and intra-chain non-bonding interactions and a high\nfrequency one corresponding principally to vibrations of bonded beads that\nconstitute skeletal chain backbones. Upon increasing the steepness of the\nangular potential, vibrational modes associated with chain bending gradually\nmove from the low-frequency to the high-frequency band. This redistribution of\nmodes is reflected in a reduction of the so-called Boson peak upon increasing\nchain stiffness. Remarkably, the finer structure and the peaks of the\nhigh-frequency band, and their variations with stiffness, can, for short\nchains, be explained using an analytical solution derived for a model triatomic\nmolecule. For longer chains, the qualitative evolution of the VDOS with chain\nstiffness is similar, although the distinct peaks observed for short chains\nbecome increasingly smoothed-out. Our findings can be used to guide a\nsystematic approach to interpretation of Brillouin and Raman scattering spectra\nof glassy polymers in future work, with applications in polymer processing\ndiagnostics."
    },
    {
        "anchor": "Two Modes of Cluster Dynamics Govern the Viscoelasticity of Colloidal\n  Gels: Colloidal gels formed by strongly attractive particles at low particle volume\nfractions are composed of space-spanning networks of uniformly sized clusters.\nWe study the thermal fluctuations of the clusters using differential dynamic\nmicroscopy by decomposing them into two modes of dynamics, and link them to the\nmacroscopic viscoelasticity via rheometry. The first mode, dominant at early\ntimes, represents the localized, elastic fluctuations of individual clusters.\nThe second mode, pronounced at late times, reflects the collective,\nviscoelastic dynamics facilitated by the connectivity of the clusters. By\nmixing two types of particles of distinct attraction strengths in different\nproportions, we control the transition time at which the collective mode starts\nto dominate, and hence tune the frequency dependence of the linear viscoelastic\nmoduli of the binary gels.",
        "positive": "Anomalous fluctuations of nematic order in solutions of semiflexible\n  polymers: The nematic ordering in semiflexible polymers with contour length $L$\nexceeding their persistence length $\\ell_p$ is described by a confinement of\nthe polymers in a cylinder of radius $r_{eff}$ much larger than the radius\n$r_\\rho$, expected from the respective concentration of the solution. Large\nscale Molecular Dynamics simulations combined with Density Functional Theory\nare used to locate the Isotropic-Nematic ($I-N$)-transition and to validate\nthis cylindrical confinement. Anomalous fluctuations, due to chain deflections\nfrom neighboring chains in the nematic phase are proposed. Considering\ndeflections as collective excitations in the nematically ordered phase of\nsemiflexible polymers elucidates the origins of shortcomings in the description\nof the $I-N$ transition by existing theories."
    },
    {
        "anchor": "Correlation and shear bands in a plastically deformed granular medium: Recent experiments (Le Bouil et al., Phys. Rev. Lett., 2014, 112, 246001)\nhave analyzed the statistics of local deformation in a granular solid\nundergoing plastic deformation. Experiments report strongly anisotropic\ncorrelation between events, with a characteristic angle that was interpreted\nusing elasticity theory and the concept of Eshelby transformations with\ndilation; interestingly, the shear bands that characterize macroscopic failure\noccur at an angle that is different from the one observed in microscopic\ncorrelations. Here, we interpret this behavior using a mesoscale elastoplastic\nmodel of solid flow that incorporates a local Mohr-Coulomb failure criterion.\nWe show that the angle observed in the microscopic correlations can be\nunderstood by combining the elastic interactions associated with Eshelby\ntransformation with the local failure criterion. At large strains, we also\ninduce permanent shear bands at an angle that is different from the one\nobserved in the correlation pattern. We interpret this angle as the one that\nleads to the maximal instability of slip lines.",
        "positive": "Motility Induced Phase Separation and Frustration in Active Matter\n  Swarmalators: We introduce a system of active matter swarmalators composed of elastically\ninteracting run-and-tumble active disks with an internal phase $\\phi_i$. The\ndisks experience an additional attractive or repulsive force with neighboring\ndisks depending upon their relative difference in $\\phi_i$. In the absence of\nthe internal phase, the system forms a Motility-Induced Phase Separated (MIPS)\nstate, but when the swarmalator interactions are present, a wide variety of\nother active phases appear depending upon whether the interaction is attractive\nor repulsive and whether the particles act to synchronize or anti-synchronize\ntheir internal phase values. These include a gas-free gel regime, arrested\nclusters, a labyrinthine state, a regular MIPS state, a frustrated MIPS state\nfor attractive anti-synchronization, and a superlattice MIPS state for\nattractive synchronization."
    },
    {
        "anchor": "Mechanical approach to surface tension and capillary phenomena: Many textbooks dealing with surface tension favor the thermodynamic approach\n(minimization of some thermodynamic potential such as free energy) over the\nmechanical approach (balance of forces) to describe capillary phenomena,\nstating that the latter is flawed and misleading. Yet, mechanical approach is\nmore intuitive for students than free energy minimization, and does not require\nany knowledge of thermodynamics. In this paper we show that capillary phenomena\ncan be unmistakably described using the mechanical approach, as long as the\nsystem on which the forces act is properly defined. After reminding the\nmicroscopic origin of a tangential tensile force at the interface, we derive\nthe Young-Dupr{\\'e} equation, emphasizing that this relation should be\ninterpreted as an interface condition at the contact line, rather than a force\nbalance equation. This correct interpretation avoids misidentification of\ncapillary forces acting on a given system. Moreover, we show that a reliable\nmethod to correctly identify the acting forces is to define a control volume\nthat does not embed any contact line on its surface. Finally, as an\nillustration of this method, we apply the mechanical approach in a variety of\nways on a classic example: the derivation of the equilibrium height of\ncapillary rise (Jurin's law).",
        "positive": "Memory-induced alignment of colloidal dumbbells: When a colloidal probe is forced through a viscoelastic fluid which is\ncharacterized by a long stress-relaxation time, the fluid is excited out of\nequilibrium. This is leading to a number of interesting effects including a\nnon-trivial recoil of the probe when the driving force is removed. Here, we\nexperimentally and theoretically investigate the transient recoil dynamics of\nnon-spherical particles, i.e., colloidal dumbbells. In addition to a\ntranslational recoil of the dumbbells, we also find a pronounced angular\nreorientation which results from the relaxation of the surrounding fluid. Our\nfindings are in good agreement with a Langevin description based on the\nsymmetries of a director (dumbbell) as well as a microscopic bath-rod model.\nRemarkably, we find a frustrated state with amplified fluctuations when the\ndumbbell is oriented perpendicular to the direction of driving. Our results\ndemonstrate the complex behavior of non-spherical objects within a relaxing\nenvironment which are of immediate interest for the motion of externally but\nalso self-driven asymmetric objects in viscoelastic fluids."
    },
    {
        "anchor": "Reactive glass and vegetation patterns: The formation of vegetation patterns in the arid and the semi-arid climatic\nzones is studied. Threshold for the biomass of the perennial flora is shown to\nbe a relevant factor, leading to a frozen disordered patterns in the arid zone.\nIn this ``glassy'' state, vegetation appears as a singular plant spots\nseparated by irregular distances, and an indirect repulsive interaction among\nshrubs is induced by the competition for water. At higher precipitation rates,\nthe diminish of hydrological losses in the presence of flora becomes important\nand yields spatial attraction and clustering of biomass. Turing-like patterns\nwith characteristic length scale may emerge from the disordered structure due\nto this positive feedback instability.",
        "positive": "Adaptive Resolution Simulation of Liquid Water: We present a multiscale simulation of liquid water where a spatially adaptive\nmolecular resolution procedure allows for changing on-the-fly from a\ncoarse-grained to an all-atom representation. We show that this approach leads\nto the correct description of all essential thermodynamic and structural\nproperties of liquid water."
    },
    {
        "anchor": "Self-consistent calculation of the autolocalization barrier for\n  quasiparticles in anisotropic crystal: The energy of the electron wave packet interacting with lattice distortion,\nis considered in anisotropic crystal. Anisotropy of the electron and phonon\nspectra as well as of the electron-phonon interaction are taken into account.\nThe height of the barrier between free and self-trapped states is calculated in\ndependence on the anisotropy parameters. The calculation is done numerically,\nusing continual aproximation. The analytical solution is obtained for some\ncases of quasi-two and quasi-one-dimensional spectra. Key words: anisotropy;\npolarons; barrier.",
        "positive": "Self-Consistent Field Theory of Inhomogeneous Polymeric Systems: A\n  Variational Derivation: The self-consistent field theory (SCFT) is a powerful framework for the study\nof the phase behavior and structural properties of many-body systems. In\nparticular, polymeric SCFT has been successfully applied to inhomogeneous\npolymeric systems such as polymer blends and block copolymer melts. The\npolymeric SCFT is commonly derived using field-theoretical techniques. Here we\nprovide an alternative derivation of the SCFT equations and SCFT free energy\nfunctional using a variational principle. Numerical methods of solving the SCFT\nequations and applications of the SCFT are also briefly introduced."
    },
    {
        "anchor": "Quadratic-stretch elasticity: A nonlinear small-strain elastic theory is constructed from a systematic\nexpansion in Biot strains, truncated at quadratic order. The primary motivation\nis the desire for a clean separation between stretching and bending energies\nfor shells, which appears to arise only from reduction of a bulk energy of this\ntype. An approximation of isotropic invariants, bypassing the solution of a\nquartic equation or computation of tensor square roots, allows stretches,\nrotations, stresses, and balance laws to be written in terms of derivatives of\nposition. Two-field formulations are also presented. Extensions to anisotropic\ntheories are briefly discussed.",
        "positive": "Weak localization and antilocalization in semiconducting polymer\n  sandwich devices: We have performed magnetoresistance measurements on polyfluorene sandwich\ndevices in weak magnetic fields as a function of applied voltage, device\ntemperature (10K to 300K), film thickness and electrode materials. We observed\neither negative or positive magnetoresistance, dependent mostly on the applied\nvoltage, with a typical magnitude of several percent. The shape of the\nmagnetoresistance curve is characteristic of weak localization and\nantilocalization. Using weak localization theory, we find that the\nphase-breaking length is relatively large even at room temperature, and\nspin-orbit interaction is a function of the applied electric field."
    },
    {
        "anchor": "Glassy Dynamics in Polyalcohols: Intermolecular Simplicity vs.\n  Intramolecular Complexity: Using depolarized light scattering, we have recently shown that structural\nrelaxation in a broad range of supercooled liquids follows, to good\napproximation, a generic line shape with high-frequency power law\n$\\omega^{-1/2}$. We now continue this study by investigating a systematic\nseries of polyalcohols (PAs), frequently used as model systems in\nglass-science, i.a., because the width of their respective dielectric loss\nspectra varies strongly along the series. Our results reveal that the\nmicroscopic origin of the observed relaxation behavior varies significantly\nbetween different PAs: While short-chained PAs like glycerol rotate as more or\nless rigid entities and their light scattering spectra follow the generic\nshape, long-chained PAs like sorbitol display pronounced intramolecular dynamic\ncontributions on the time scale of structural relaxation, leading to systematic\ndeviations from the generic shape. Based on these findings we discuss an\nimportant limitation for observing the generic shape in a supercooled liquid:\nThe dynamics that is probed needs to reflect the intermolecular dynamic\nheterogeneity, and must not be superimposed by effects of intramolecular\ndynamic heterogeneity.",
        "positive": "Shape-shifting droplet networks: We consider a three-dimensional network of aqueous droplets joined by single\nlipid bilayers to form a cohesive, tissue-like material. The droplets in these\nnetworks can be programmed to have distinct osmolarities so that osmotic\ngradients generate internal stresses via local fluid flows to cause the network\nto change shape. We discover, using molecular dynamics simulations, a\nreversible folding-unfolding process by adding an osmotic interaction with the\nsurrounding environment which necessarily evolves dynamically as the shape of\nthe network changes. This discovery is the next important step towards osmotic\nrobotics in this system. We also explore analytically and numerically how the\nnetworks become faceted via buckling and how quasi-one-dimensional networks\nbecome three-dimensional."
    },
    {
        "anchor": "Tuning contact line dynamics and deposition patterns in volatile liquid\n  mixtures: The spreading of a pure, volatile liquid on a wettable substrate has been\nstudied in extensive detail. Here we show that the addition of a miscible,\nnon-volatile liquid can strongly alter the contact line dynamics and the final\nliquid deposition pattern. We observe two distinct regimes of behavior\ndepending on the relative strength of solutal Marangoni forces and surface\nwetting. Finger-like instabilities precede the deposition of a sub-micron thick\nfilm for large Marangoni forces and small solute contact angles, whereas\nisolated, pearl-like drops emerge and are deposited in quasi-crystalline\npatterns for small Marangoni forces and large solute contact angles. This\nbehavior can be tuned by directly varying the contact angle of the solute\nliquid on the solid substrate.",
        "positive": "Protein mechanical unfolding: a model with binary variables: A simple lattice model, recently introduced as a generalization of the\nWako--Sait\\^o model of protein folding, is used to investigate the properties\nof widely studied molecules under external forces. The equilibrium properties\nof the model proteins, together with their energy landscape, are studied on the\nbasis of the exact solution of the model. Afterwards, the kinetic response of\nthe molecules to a force is considered, discussing both force clamp and dynamic\nloading protocols and showing that theoretical expectations are verified. The\nkinetic parameters characterizing the protein unfolding are evaluated by using\ncomputer simulations and agree nicely with experimental results, when these are\navailable. Finally, the extended Jarzynski equality is exploited to investigate\nthe possibility of reconstructing the free energy landscape of proteins with\npulling experiments."
    },
    {
        "anchor": "Modeling Complex Liquid Crystals Mixtures: From Polymer Dispersed\n  Mesophase to Nematic Nanocolloids: Liquid crystals are synthetic and biological viscoelastic anisotropic soft\nmatter materials that combine liquid fluidity with crystal anisotropy and find\nuse in optical devices, sensor/actuators, lubrication, super-fibers. Frequently\nmesogens are mixed with colloidal and nanoparticles, other mesogens, isotropic\nsolvents, thermoplastic polymers, cross-linkable monomers, among others. This\ncomprehensive review present recent progress on meso and macro scale\nthermodynamic modelling, highlighting the (i) novelties in spinodal and binodal\nlines in the various phase diagrams, (ii) the growth laws under phase\ntransitions and phase separation, (iii) the ubiquitous role of metastability\nand its manifestation in complex droplet interfaces, (iv) the various spinodal\ndecompositions due to composition and order fluctuations, (v) the formation of\nnovel material architectures such as colloidal crystals, (vi) the particle rich\nphase behaviour in liquid crystal nanocomposites, (vii) the use of topological\ndefects to absorb and organize nanoparticles, and (viii) the ability of faceted\nnanoparticles to link into strings and organize into lattices. Emphasis is\ngiven to highlight dominant mechanisms and driving forces, and to link them to\nspecific terms in the free energies of these complex mixtures. The novelties of\nincorporating mesophases into blends, solutions, dispersions and mixtures is\nrevealed by using theory, modelling, computation, and visualization.",
        "positive": "Fundamental measure theory for the electric double layer: implications\n  for blue-energy harvesting and water desalination: Capacitive mixing (CAPMIX) and capacitive deionization (CDI) are promising\ncandidates for harvesting clean, renewable energy and for the energy efficient\nproduction of potable water, respectively. Both CAPMIX and CDI involve\nwater-immersed porous carbon (supercapacitors) electrodes at voltages of the\norder of hundreds of millivolts, such that counter-ionic packing is important\nfor the electric double layer (EDL) which forms near the surface of these\nporous materials. Thus, we propose a density functional theory (DFT) to model\nthe EDL, where the White-Bear mark II fundamental measure theory functional is\ncombined with a mean-field Coulombic and a mean spherical approximation-type\ncorrection to describe the interplay between dense packing and electrostatics,\nin good agreement with molecular dynamics simulations. We discuss the\nconcentration-dependent potential rise due to changes in the chemical potential\nin capacitors in the context of an over-ideal theoretical description and its\nimpact on energy harvesting and water desalination. Compared to less elaborate\nmean-field models our DFT calculations reveal a higher work output for\nblue-energy cycles and a higher energy demand for desalination cycles."
    },
    {
        "anchor": "Brute-force nucleation rates of hard spheres compared with rare-event\n  methods and classical nucleation theory: We determine the nucleation rates of hard spheres using brute-force molecular\ndynamics simulations. We overcome nucleation barriers of up to $28 k_B T$,\nleading to a rigorous test of nucleation rates obtained from rare-event methods\nand classical nucleation theory. Our brute-force nucleation rates show\nexcellent agreement with umbrella sampling simulations by Filion et al. [J.\nChem. Phys. 133, 244115 (2010)] and seeding simulations by Espinosa et al. [J.\nChem. Phys. 144, 034501 (2016)].",
        "positive": "Exactly solvable model for a velocity jump observed in crack propagation\n  in viscoelastic solids: Needs to impart appropriate elasticity and high toughness to viscoelastic\npolymer materials are ubiquitous in industries such as concerning automobiles\nand medical devices. One of the major problems to overcome for toughening is\ncatastrophic failure linked to a velocity jump, i.e., a sharp transition in the\nvelocity of crack propagation occurred in a narrow range of the applied load.\nHowever, its physical origin has remained an enigma despite previous studies\nover 35 years. Here, we propose an exactly solvable model that exhibits the\nvelocity jump incorporating linear viscoelasticity with a cutoff length for a\ncontinuum description. With the exact solution, we elucidate the physical\norigin of the velocity jump: it emerges from a dynamic glass transition in the\nvicinity of the propagating crack tip. We further quantify the velocity jump\ntogether with slow- and fast-velocity regimes of crack propagation, which would\nstimulate the development of tough polymer materials."
    },
    {
        "anchor": "Similarity and contrasts between thermodynamic properties at the\n  critical point of liquid alkali metals and of electron-hole droplets: The recent experimental study by means of time-resolved luminescence\nmeasurements of an electron-hole liquid (EHL) in diamond by Shimano et al.\n[Phys. Rev. Lett. 88 (2002) 057404] prompts us to compare and contrast critical\ntemperature T_c and critical density n_c relations in liquid alkali metals with\nthose in electron-hole liquids. The conclusion drawn is that these systems have\nsimilarities with regard to critical properties. In both cases the critical\ntemperature is related to the cube root of the critical density. The existence\nof this relation is traced to Coulomb interactions and to systematic trends in\nthe dielectric constant of the electron-hole systems. Finally a brief\ncomparison between the alkalis and EHLs of the critical values for the\ncompressibility ratio Z_c is also given.",
        "positive": "Novel fluctuations at constrained interfaces: In this study we try to answer the qustion : What happens when explicit\nconstraints are introduced such that the low energy, long wavelength modes of a\nsystem are unavailable ? This question has assumed some importance in recent\nyears due to the advent of nano technology and the growing use of nanometer\nscale devices and structures. In a small system, the size limits the scale of\nthe fluctuations and makes it imperative for us to understand how the response\nof the system is altered in such a situation. In this thesis, this question is\nanswered for the special case of interfacial fluctuations in two dimensions\n(2d). The energy of an interface between two phases in equilibrium is invariant\nwith respect to translations perpendicular to the plane (or line in 2d) of the\ninterface. We study the consequence of breaking this symmetry explicity using\nan external field gradient. One expects that since low energy excitations are\nsuppressed, the interface would be flat and inert at all times. We show that\nsurprisingly there are novel fluctuations and phenomena associated with such\nconstrained interfaces which have static as well as dynamic consequences. The\nIsing interface on a square lattice is shown to undergo a multitude of\nstructural transitions as a function of velocity and the orientation. Liquid\nsolid interfaces show coherent addition and removal of atomic layers providing\nnovel mechanisms of stress relaxation in a nanosized single crystal without\ndefects. We study momentum and energy transfer across the liquid solid\ninterface in the presence of this ``layering'' transition."
    },
    {
        "anchor": "Model for Assembly and Gelation of Four-Armed DNA Dendrimers: We introduce and numerically study a model designed to mimic the bulk\nbehavior of a system composed of single-stranded DNA dendrimers.\nComplementarity of the base sequences of different strands results in the\nformation of strong cooperative intermolecular links. We find that in an\nextremely narrow temperature range the system forms a large-scale, low-density\ndisordered network via a thermo-reversible gel transition. By controlling the\nstrand length, the gel transition temperature can be made arbitrarily close to\nthe percolation transition, in contrast with recent model systems of physical\ngelation. This study helps the understanding of self-assembly in this class of\nnew biomaterials and provides an excellent bridge between physical and chemical\ngels.",
        "positive": "Probing the Viscoelastic Properties of Aqueous Protein Solutions using\n  Molecular Dynamics Simulations: We performed molecular dynamics simulations to investigate the viscoelastic\nproperties of aqueous protein solutions containing an antifreeze protein, a\ntoxin protein, and bovine serum albumin. These simulations covered a\ntemperature range from 280 K to 340 K. Our findings demonstrate that lower\ntemperatures are associated with higher viscosity as well as a lower bulk\nmodulus and speed of sound for all the systems studied. Furthermore, we observe\nan increase in the bulk modulus and speed of sound as the temperature increases\nup to a weak maximum while the viscosity decreases. Moreover, we analyzed the\ninfluence of protein concentration on the viscoelastic properties of the\nantifreeze protein solution. We observed a consistent increase in the bulk\nmodulus, speed of sound, and viscosity as the protein concentration increased.\nRemarkably, our molecular dynamics simulations results closely resemble the\ntrends observed in Brillouin scattering experiments on aqueous protein\nsolutions. The similarity thus validates the use of simulations in studying the\nviscoelastic properties of protein water solutions. Ultimately, this work\nprovides motivation for the integration of computer simulations with\nexperimental data and holds potential for advancing our understanding of both\nsimple and complex systems."
    },
    {
        "anchor": "Dewetting of thin-film polymers: In this paper we present a theoretical model for the dewetting of ultra-thin\npolymer films. Assumming that the shear-thinning properties of these films can\nbe described by a Cross-type constitutive equation, we analyze the front\nmorphology of the dewetting film, and characterize the time evolution of the\ndry region radius, and of the rim height. Different regimes of growth are\nexpected, depending on the initial film thickness, and on the power-law index\ninvolved in the constitutive equation. In the thin-films regime, the dry radius\nand the rim height obey power-law time dependences. We then compare our\npredictions with the experimental results obtained by Debr\\'egeas {\\it et al.}\n[Phys. Rev. Lett. {\\bf 75}, 3886 (1995)] and by Reiter [Phys. Rev. Lett. {\\bf\n87}, 186101 (2001)].",
        "positive": "Role of ionic liquids in protein refolding: native/fibrillar versus\n  treated lysozyme: Several ionic liquids (ILs) are known to revert aggregation processes and\nimprove the in vitro refolding of denatured proteins. In this paper the\ncapacity of a particular class of ammonium based ILs to act as refolding\nenhancers was tested using lysozyme as a model protein. Raman spectra of ILs\ntreated fibrillar lysozyme as well as lysozyme in its native and fibrillar\nconformations were collected and carefully analyzed to characterize the\nrefolding extent under the effect of the IL interaction. Results obtained\nconfirm and largely extend the earlier knowledge on this class of protic ILs\nand indicate Ethyl Ammonium Nitrate (EAN) as the most promising additive for\nprotein refolding. The experiment provides also the demonstration of the high\npotentiality of Raman spectroscopy as a comprehensive diagnostic tool in this\nfield."
    },
    {
        "anchor": "Budding and vesiculation induced by conical membrane inclusions: Conical inclusions in a lipid bilayer generate an overall spontaneous\ncurvature of the membrane that depends on concentration and geometry of the\ninclusions. Examples are integral and attached membrane proteins, viruses, and\nlipid domains. We propose an analytical model to study budding and vesiculation\nof the lipid bilayer membrane, which is based on the membrane bending energy\nand the translational entropy of the inclusions. If the inclusions are placed\non a membrane with similar curvature radius, their repulsive membrane-mediated\ninteraction is screened. Therefore, for high inclusion density the inclusions\naggregate, induce bud formation, and finally vesiculation. Already with the\nbending energy alone our model allows the prediction of bud radii. However, in\ncase the inclusions induce a single large vesicle to split into two smaller\nvesicles, bending energy alone predicts that the smaller vesicles have\ndifferent sizes whereas the translational entropy favors the formation of\nequal-sized vesicles. Our results agree well with those of recent computer\nsimulations.",
        "positive": "Molecular simulation study of polar order in orthogonal bent core\n  smectic liquid crystals: We explore the phase behavior and structure of orthogonal smectic liquid\ncrystals consisting of bent-core molecules (BCMs) by means of Monte Carlo\nmolecular simulations. A simple athermal molecular model is introduced that\ndescribes the basic features of the BCMs. Phase transitions between uniaxial\nand biaxial (antiferroelectric) orthogonal smectics are obtained. The results\nindicate the presence of local in-plane polar correlations in the uniaxial\nsmectic phase. The macroscopic uniaxial-biaxial transformation is rationalized\nin terms of local polar correlations giving rise to polar domains. The size of\nthese polar domains grows larger under the action of an external vector field\nand their internal ordering is enhanced, leading to field-induced biaxial\norder-disorder transitions."
    },
    {
        "anchor": "Surface Alignment, Anchoring Transitions, Optical Properties, and\n  Topological Defects in the Thermotropic Nematic Phase of an Organo-Siloxane\n  Tetrapodes: We perform optical, surface anchoring, and textural studies of an\norgano-siloxane tetrapode material in the broad temperature range of the\nnematic phase. The optical, structural, and topological features are compatible\nwith the uniaxial nematic order rather than with the biaxial nematic order, in\nthe entire nematic temperature range -25C < T < 46C studied. For homeotropic\nalignment, the material experiences surface anchoring transition, but the\ndirector can be realigned into an optically uniaxial texture by applying a\nsufficiently strong electric field. The topological features of textures in\ncylindrical capillaries, in spherical droplets and around colloidal inclusions\nare consistent with the uniaxial character of the long-range nematic order. In\nparticular, we observe isolated surface point defect-boojums and bulk point\ndefects-hedgehog that can exist only in the uniaxial nematic.",
        "positive": "Order from disorder with intrinsically disordered peptide amphiphiles: Amphiphilic molecules and their self-assembled structures have long been the\ntarget of extensive research due to their potential applications in fields\nranging from materials design to biomedical and cosmetic applications.\nIncreasing demands for functional complexity have been met with challenges in\nbiochemical engineering, driving researchers to innovate in the design of new\namphiphiles. An emerging class of molecules, namely, peptide amphiphiles,\ncombines key advantages and circumvents some of the disadvantages of\nconventional phospholipids and block-copolymers. Herein, we present new peptide\namphiphiles comprised of an intrinsically disordered peptide conjugated to two\nvariants of hydrophobic dendritic domains. These molecules termed intrinsically\ndisordered peptide amphiphiles (IDPA), exhibit a sharp pH-induced micellar\nphase-transition from low-dispersity spheres to extremely elongated worm-like\nmicelles. We present an experimental characterization of the transition and\npropose a theoretical model to describe the pH-response. We also present the\npotential of the shape transition to serve as a mechanism for the design of a\ncargo hold-and-release application. Such amphiphilic systems demonstrate the\npower of tailoring the interactions between disordered peptides for various\nstimuli-responsive biomedical applications."
    },
    {
        "anchor": "Rheological properties of dense granular flows: Recent progresses in understanding the behavior of dense granular flows are\npresented. After presenting a bulk rheology of granular materials, I focus on\nthe new developments to account for non-local effects, and on ongoing research\nconcerning the surface rheology and the evolution of mechanical properties for\nheterogeneous systems.",
        "positive": "A microscopic approach to the nonlinear elasticity of compressed\n  emulsions: Using confocal microscopy, we measure the packing geometry and interdroplet\nforces as a function of the osmotic pressure in a 3D emulsion system. We find\nthat the nonlinear elastic response of the pressure with density is not a\nresult of the anharmonicity in the interaction potential, but of the\ncorrections to the scaling laws of the microstructure away from the critical\npoint. The bulk modulus depends on the excess contacts created under\ncompression, which leads to the correction exponent \\alpha=1.5.\nMicroscopically, the nonlinearities manifest themselves as a narrowing of the\ndistribution of the pressure per particle as a function of the global pressure."
    },
    {
        "anchor": "Transport and selective chaining of bidisperse particles in a travelling\n  wave potential: We combine experiments, theory and numerical simulation to investigate the\ndynamics of a binary suspension of paramagnetic colloidal particles dispersed\nin water and transported above a stripe patterned magnetic garnet film. The\nsubstrate generates a one-dimensional periodic energy landscape above its\nsurface. The application of an elliptically polarized rotating magnetic field\ncauses the landscape to translate, inducing direct transport of paramagnetic\nparticles placed above the film. The ellipticity of the applied field can be\nused to control and tune the interparticle interactions, from net repulsive to\nnet attractive. When considering particles of two distinct sizes, we find that,\ndepending on their elevation above the surface of the magnetic substrate, the\nparticles feel effectively different potentials, resulting in different\nmobilities. We exploit this feature to induce selective chaining for certain\nvalues of the applied field parameters. In particular, when driving two types\nof particles, we force only one type to condense into travelling parallel\nchains. These chains confine the movement of the other non-chaining particles\nwithin narrow colloidal channels. This phenomenon is explained by considering\nthe balance of pairwise magnetic forces between the particles and their\nindividual coupling with the travelling landscape.",
        "positive": "Approach to jamming in an air-fluidized granular bed: Quasi-2D bidisperse amorphous systems of steel beads are fluidized by a\nuniform upflow of air, so that the beads roll on a horizontal plane. The\nshort-time ballistic motion of the beads is stochastic, with non-Gaussian speed\ndistributions and with different average kinetic energies for the two species.\nThe approach to jamming is studied as a function of increasing bead area\nfraction and also as a function of decreasing air speed. The structure of the\nsystem is measured in terms of both the Voronoi tessellation and the pair\ndistribution function. The dynamics of the system is measured in terms of both\ndisplacement statistics and the density of vibrational states. These quantities\nall exhibit tell-tale features as the dynamics become more constrained closer\nto jamming. Though the system is driven and athermal, the behavior is\nremarkably reminiscent of that in dense colloidal suspensions and supercooled\nliquids."
    }
]